Mélanie Tremblay, M.Sc.

Hepatic encephalopathy (HE) is a debilitating neurological complication of cirrhosis. By definition, HE is considered a reversible disorder, and therefore HE should resolve following liver transplantation (LT). However, persisting neurological complications are observed in as many as 47% of LT recipients. LT is an invasive surgical procedure accompanied with various perioperative factors such as blood loss and hypotension which could influence outcomes post-LT. We hypothesize that minimal HE (MHE) renders the brain frail and susceptible to hypotension-induced neuronal cell death. Six-week bile duct-ligated (BDL) rats with MHE and respective SHAM-controls were used. Several degrees of hypotension (mean arterial pressure of 30, 60 and 90mmHg) were induced via blood withdrawal from the femoral artery and maintained for 120 minutes. Brains were collected for neuronal cell count and apoptotic analysis. In a separate group, BDL rats were treated for MHE with the ammonia-lowering strategy ornithine phenylacetate (OP; MNK-6105), administered orally (1g/kg) for 3 weeks before induction of hypotension. Hypotension 30 and 60mmHg (not 90mmHg) significantly decreased neuronal marker expression (NeuN) and cresyl violet staining in the frontal cortex compared to respective hypotensive SHAM-operated controls as well as non-hypotensive BDL rats. Neuronal degeneration was associated with an increase in cleaved caspase-3, suggesting the mechanism of cell death was apoptotic. OP treatment attenuated hyperammonemia, improved anxiety and activity, and protected the brain against hypotension-induced neuronal cell death. Our findings demonstrate that rats with chronic liver disease and MHE are more susceptible to hypotension-induced neuronal cell degeneration. This highlights MHE at the time of LT is a risk factor for poor neurological outcome post-transplant and that treating for MHE pre-LT might reduce this risk.

Introduction: Hepatic Encephalopathy (HE) is a severe neuropsychiatric syndrome associated with liver failure, ranging from covert HE, with subclinical impairments, to overt HE, with evident symptoms that require hospitalization. HE can be prevented, but prophylaxis would be justified and cost-effective only for patients at risk. Efficient and practical screening models are needed to detect these patients. EncephalApp, smartphone-based Stroop test is a valid method to screen for covert HE, one of the main risk factors. • Objective: Identify patients who are at high risk of developing overt hepatic encephalopathy within one year. • Hypothesis: The risk of developing an overt HE episode within 1 year and mortality will be higher in patients with covert HE and with a high risk of decompensation due to cirrhosis measured by ALBI-FIB4 score. Presence of ascites, high risk of gastrointestinal bleeding and high levels of inflammation biomarkers associated with covert HE at the screening are also expected to predict the outcomes. • Methods: For a multicentric longitudinal prospective study, 25 to 30 cirrhotic patients will be selected from 7 centers in Canada: Montreal (2 centers), Toronto, Ottawa, Calgary, Vancouver and Edmonton. Covert HE will be diagnosed with the Stroop test and blood samples will be collected at the screening and at the hospitalizations. Patients will be followed up for 1 year with phone calls every 3 months and medical records will be checked to identify HE- related hospitalizations and mortality. Statistical analysis will be performed to study the correlation between screening test results and patient outcomes. • Conclusion: The expected results can provide important information for identifying patients at high risk of developing overt HE within 1 year, by diagnosing covert HE and measuring biomarkers linked to the HE risk pathway. This data can help to justify prophylaxis, early treatment and prevention of episodes, which would have a great impact on the patient's quality of life, cost of health treatments and decrease in mortality.

Background: Sarcopenia is associated with a worst prognosis in cirrhotic patients after liver transplantation (LT). As patients gain weight and sarcopenia remains after LT, sarcopenic obesity (SO) develops. Metabolic syndrome (MS), a cluster of factors that increase the risk of heart disease and diabetes, is caused by weight gain. There are limited data about the influence of SO and MS in LT recipients. Purpose: The goal of this study was to examine the impact of SO and MS on outcome after LT. Method: In total, 94 cirrhotic patients who underwent LT at the CHUM – Liver Unit were included. Sarcopenia was assessed at the third lumbar level vertebrae using a CT-scan. Obesity was determined using BMI whereas MS was diagnosed using the presence of ³3 modified NCEP ATP III criteria. The prognostic factors were collected 6 months before and during 1 year after LT through medical records and included number of complications, episodes of infections, length of stay, and frequency of readmissions. Result(s): Most of the patients ( 70%) were not obese before LT. Approximately 20% of the patients developed obesity after LT. Among patients who were obese before LT, 40% of the patients remained obese after LT. SO affected 10% and less of the patients before and after LT. Among patients with MS before LT (64%), 40% of them was still affected after LT. Among patients who were not affected by MS before LT, 38% developed MS after LT and one patient remained not affected after LT. Prognostic factors were worst in patients with SO and MS before and after LT. Conclusion(s): SO affected a small proportion of patients while MS was prevalent before and after LT. Nevertheless, these conditions were associated with worst prognosis. Strategies to manage SO and MS could help to improve recovery in patients who have undergone LT.

Background The impact of sex differences on chronic liver disease (CLD) and hepatic encephalopathy (HE) is unknown. The majority of animals used in research are male since the main difficulty with using female animals is the potential impact of the estrous cycle which increases intra-group variability. The bile duct ligated (BDL) rat is a well-characterized model of CLD and HE in males, which has not been investigated in females. Therefore, we aimed to characterize a female BDL model of CLD and HE and compare to male BDL rats. Material and methods Female rats underwent either BDL (n=8) or Sham (n=8) surgery. After 5 weeks, we assessed estrous cycle phase (by cellular cytology), anxiety (open field test), motor incoordination (rota-rod test) and night-time activity. We also assessed body weight, body composition (MRI), gastrocnemius muscle weight/circumference, grip strength, plasma ammonia and liver enzymes. Results from female BDL rats were compared to historical laboratory data from male BDL rats. Results Female BDL rats had increased markers of liver injury: ALP, AST and bilirubin (p<0.001) and impaired markers of liver function (increased ammonia and decreased albumin (p<0.001)) compared to female Shams. Furthermore, Female BDL rats did not differ in body weight, muscle circumference/weight and grip strength but had decreased fat mass (p<0.0001) and increased lean mass (p<0.005) compared to female shams. All results were comparable to male BDL rats except for plasma ammonia levels which were significantly lower in females (p<0.01). Moreover, male BDL rats had decreased fat mass, lean mass, muscle circumference/weight and grip strength. BDL surgery in female rats induced a dysregulated estrous cycle compared to sham (increased metestrus phase (p<0.01)). However, similar to male BDL rats, female BDL rats had increased anxiety (p<0.005), motor incoordination (p<0.05), and decreased night activity (p<0.05), independent of the estrous cycle phase. Discussion We demonstrated BDL surgery in females leads to hepatic and neurological impairment comparable to male BDL rats (similar intra-group variability). Interestingly, female BDL rats developed unique features. Contrary to male BDL vs. Shams, body weight and muscle mass did not differ between female BDL and Shams. Since muscle mass plays an important compensatory role in regulating ammonia levels, this could explain the reason why blood ammonia levels in female BDL rats are significantly lower compared to male BDL rats. We expect that this model will provide new insights on the effect of sex differences on the pathogenesis of CLD and HE and help to personalize HE treatment.

Background: Non-alcoholic fatty liver disease (NAFLD) is associated with type II diabetes (T2D) and has become the main cause of cirrhosis. Both NAFLD and T2D are associated with cognitive and neurological impairments. T2D has been established as a risk factor for first-time development of overt hepatic encephalopathy (HE) in cirrhotic patients. The onset of HE in diabetic patients with cirrhosis develops earlier compared to cirrhosis patients without T2D. However it remains unclear whether NAFLD-induced cirrhosis increases the risk for HE. The present study aims to address the association between NAFLD, T2D and HE. Methods: Our retrospective study includes 102 cirrhotic patients on the liver transplant list at the Liver Unit of the Montreal University Hospital Center. Patients were classified by etiology of cirrhosis; 1) NAFLD and 2) non-NAFLD. Demographic data, blood biochemistry, clinical information on T2D-related comorbidities and cirrhosis complications (including number and severity of HE episodes) were collected. These factors were statistically associated with HE episodes. Results: Our cohort comprised 20 (19%) NAFLD and 82 (79%) non-NAFLD patients presenting similar MELD and Child-Pugh scores. The prevalence of T2D was higher in NAFLD vs non-NAFLD cirrhotics (15 (75%) vs 24 (29%) respectively) and was associated to co-morbidities such as cardiac disease, dyslipidemia, hypertension and obesity. Among non-NAFLD cirrhotics, 47 (57%) patients had a history of HE whereas 8 (40%) were found in the NAFLD cirrhotics (p>0.05). Since T2D is already known as a risk factor for HE, we subdivided both NAFLD and non-NAFLD groups into non-T2D and T2D subgroups. HE was significantly more prevalent in patients with T2D: in the NAFLD group, 5 (25%) T2D patients had developed an episode of HE compared to 3 (15%) patients without T2D (p<0.05); in the non-NAFLD group, 16 (67%) patients had T2D and HE compared to 31 (53%) HE patients without T2D (p<0.001). Fasting glycemia levels analysis in the 4 sub-groups of patients revealed increased levels in patients with history of HE and T2D, regardless of NAFLD etiology; in the NAFLD group 8.60 ± 0.84 mmol/l in patients with HE and T2D vs 6.00 ± 1.35 mmol/l in patients with HE without T2D (p<0.01); in the non-NAFLD group: 9.23 ± 0.93 mmol/l in patients with HE and T2D vs 5.82 ± 0.27 mmol/l in patients with HE without T2D (p<0.001). Conclusion: Our results sustain the association between T2D and HE and suggest high glucose might play a pathological role in the development of cognitive decline. NAFLD is not a risk factor for the development of HE. These interesting results provide new insights in the role of T2D in the development of HE and further studies are required to understand the underlying mechanisms. Furthermore, identifying patients who are at higher risk of developing HE is imperative to initiate early treatment strategies to protect neurological decline in patients with cirrhosis.

Background: Non-alcoholic fatty liver disease (NAFLD) is associated with type II diabetes (T2D) and has become the main cause of cirrhosis. Both NAFLD and T2D are associated with cognitive and neurological impairments. T2D has been established as a risk factor for first-time development of overt hepatic encephalopathy (HE) in cirrhotic patients. The onset of HE in diabetic patients with cirrhosis develops earlier compared to cirrhosis patients without T2D. However it remains unclear whether NAFLD-induced cirrhosis increases the risk for HE. The present study aims to address the association between NAFLD, T2D and HE. Methods: Our retrospective study includes 102 cirrhotic patients on the liver transplant list at the Liver Unit of the Montreal University Hospital Center. Patients were classified by etiology of cirrhosis; 1) NAFLD and 2) non-NAFLD. Demographic data, blood biochemistry, clinical information on T2D-related comorbidities and cirrhosis complications (including number and severity of HE episodes) were collected. These factors were statistically associated with HE episodes. Results: Our cohort comprised 20 (19%) NAFLD and 82 (79%) non-NAFLD patients presenting similar MELD and Child-Pugh scores. The prevalence of T2D was higher in NAFLD vs non-NAFLD cirrhotics (15 (75%) vs 24 (29%) respectively) and was associated to co-morbidities such as cardiac disease, dyslipidemia, hypertension and obesity. Among non-NAFLD cirrhotics, 47 (57%) patients had a history of HE whereas 8 (40%) were found in the NAFLD cirrhotics (p>0.05). Since T2D is already known as a risk factor for HE, we subdivided both NAFLD and non-NAFLD groups into non-T2D and T2D subgroups. HE was significantly more prevalent in patients with T2D: in the NAFLD group, 5 (25%) T2D patients had developed an episode of HE compared to 3 (15%) patients without T2D (p<0.05); in the non-NAFLD group, 16 (67%) patients had T2D and HE compared to 31 (53%) HE patients without T2D (p<0.001). Fasting glycemia levels analysis in the 4 sub-groups of patients revealed increased levels in patients with history of HE and T2D, regardless of NAFLD etiology; in the NAFLD group 8.60 ± 0.84 mmol/l in patients with HE and T2D vs 6.00 ± 1.35 mmol/l in patients with HE without T2D (p<0.01); in the non-NAFLD group: 9.23 ± 0.93 mmol/l in patients with HE and T2D vs 5.82 ± 0.27 mmol/l in patients with HE without T2D (p<0.001). Conclusion: Our results sustain the association between T2D and HE and suggest high glucose might play a pathological role in the development of cognitive decline. NAFLD is not a risk factor for the development of HE. These interesting results provide new insights in the role of T2D in the development of HE and further studies are required to understand the underlying mechanisms. Furthermore, identifying patients who are at higher risk of developing HE is imperative to initiate early treatment strategies to protect neurological decline in patients with cirrhosis.

Introduction: Sarcopenia is associated with a worst prognosis in cirrhotic patients after liver transplantation (LT). As patients gain weight and sarcopenia remains after LT, sarcopenic obesity (SO) develops. Metabolic syndrome (MS), a cluster of factors that increase the risk of heart disease and diabetes, is caused by weight gain. There are limited data about the influence of SO and MS in LT recipients. The goal of this study was to examine the impact of SO and MS on outcomes after LT. Method: In total, 94 cirrhotic patients who underwent LT at the CHUM – Liver Unit were included. Sarcopenia was assessed at the third lumbar level vertebrae using a CT-scan. Obesity was determined using BMI whereas MS was diagnosed using the presence of 3 modified NCEP ATP III criteria. The prognostic factors were collected 6 months before and during 1 year after LT through medical records and included number of complications, episodes of infections, length of stay, and frequency of readmissions. Results: Most of the patients ( 70%) were not obese before LT. Approximately 20% of the patients developed obesity after LT. Among patients who were obese before LT, 40% of the patients remained obese after LT. SO affected 10% and less of the patients before and after LT. Among patients with MS before LT (64%), 40% of them was still affected after LT. Among patients who were not affected by MS before LT, 38% developed MS after LT and one patient remained not affected after LT. Prognostic factors were worst in patients with SO and MS before and after LT. Conclusion: SO affected a small proportion of patients while MS was prevalent before and after LT. Nevertheless, these conditions were associated with worst prognosis. Strategies to manage SO and MS could help to improve recovery in patients who have undergone LT.

Ammonia-scavenging transmembrane pH-gradient poly(styrene)-b-poly(ethylene oxide) polymersomes are investigated for the oral treatment and diagnosis of hyperammonemia, a condition associated with serious neurologic complications in patients with liver disease as well as in infants with urea cycle disorders. While these polymersomes are highly stable in simulated intestinal fluids at extreme bile salt and osmolality conditions, they unexpectedly do not reduce plasmatic ammonia levels in cirrhotic rats after oral dosing. Incubation in dietary fiber hydrogels mimicking the colonic environment suggests that the vesicles are probably destabilized during the dehydration of the intestinal chyme. The findings question the relevance of commonly used simulated intestinal fluids for studying vesicular stability. With the encapsulation of a pH-sensitive dye in the polymersome core, the local pH increase upon ammonia influx could be exploited to assess the ammonia concentration in the plasma of healthy and cirrhotic rats as well as in other fluids. Due to its high sensitivity and selectivity, this polymersome-based assay could prove useful in the monitoring of hyperammonemic patients and in other applications such as drug screening tests.

Hyperammonemia associated with chronic liver disease (CLD) is implicated in the pathogenesis of hepatic encephalopathy (HE). The gut is a major source of ammonia (NH3) production that contributes to systemic hyperammonemia in CLD and HE and remains the primary therapeutic target for lowering systemic NH3. As a therapeutic strategy, Escherichia coli Nissle 1917 bacterium (EcN), a well characterized probiotic, was genetically modified to consume and convert NH3 to arginine (SYNARG), and its administration to thiaoacetamide-treated mice reduced NH3 levels. SYNARG was further modified to synthesize butyrate (SYNARG+BUT), a short-chain fatty acid with anti-inflammatory properties, and both strains were tested in an animal model of CLD and HE, the bile duct ligation (BDL). Methods: One week (wk) post surgery, BDL rats were gavaged with SYNARG, SYNARG+BUT (3x1011 CFU/day, BID) or vehicle until they were sacrificed at 3- or 5-weeks along with respective sham controls. Plasma NH3 and liver markers were measured at 3 and 5 wk. Recognition memory, motor coordination, muscle strength, locomotion and anxiety were assessed in the 5-week groups. Results: BDL increased NH3 over time, with levels of 109.1±9.2µM (Shams 56.7±3.5µM, p<0.001) and 150.2±25.6µM (Shams 58.3±3.0µM, p<0.001) at 3- and 5-wk, respectively. In addition, plasma liver markers ALT, AST, bilirubin, and GGT as well as liver fibrosis (hydroxyproline) were increased in BDL rats at both timepoints while albumin was lowered. As compared to BDL-Veh rats, NH3 was attenuated by SYNARG (103.9±12.3µM) and SYNARG+BUT (110.8±8.5µM) at 5, but not 3-wk post-BDL, while liver fibrosis was attenuated at 3, but not 5-wk post-BDL. None of the systemic liver markers were changed by the treatments at any timepoint. Motor coordination, muscle strength, locomotion and anxiety were affected in all BDL groups without protective effect of treatments. Short-term memory (STM) was impaired in BDL-Veh (p<0.001) and BDL-SYNARG (p<0.05) vs Shams, while STM was improved in BDL-SYNARG+BUT (p<0.05 vs BDL-Veh). Long-term memory was impaired in BDL-Veh vs Shams (p<0.05), but BDL-SYNARG and BDL-SYNARG+BUT were partially protected. Conclusion: EcN, engineered to consume NH3 in the gut, is an effective approach to lower plasma NH3 in a model of CLD and HE. Moreover, the attenuation of NH3 in BDL rats is related to a protective effect on memory in this model. The therapeutic potential of these strains should be further evaluated in patients with CLD and HE.

Background The impact of sex differences on chronic liver disease (CLD) and hepatic encephalopathy (HE) is unknown. The majority of animals used in research are male since the main difficulty with using female animals is the potential impact of the estrous cycle, increasing intragroup variability. The bile duct ligated (BDL) rat is a well-characterized model of CLD and HE in males which has not been investigated in females. Therefore, we aimed to characterize a female BDL model of CLD and HE and compare to male BDL rats. Material and Methods We assessed BDL or Sham female rats for estrous cycle phase, behavior (anxiety, motor incoordination and activity), body parameters (weight and composition, muscle weight/circumference, grip strength), liver parameters (enzymes and ammonia). We than compared to historical laboratory data from male BDL rats. Results Female BDL rats had impaired liver markers (P<0.0001) and ammonia (p<0.001) compared to female Shams. These results were comparable to male BDL rats except ammonia which was lower in females (p< 0.01). Female BDL rats did not differ in body weight, muscle circumference/weight and grip strength and had increased lean mass (p<0.005) compared to female shams. Whereas, male BDL rats have decreased lean mass, muscle circumference/weight and grip strength. Similar to male BDL rats, female BDL rats had increased anxiety (p<0.005), motor incoordination (p<0.05), and decreased activity (p<0.05) independent of the estrous cycle phase. Discussion and Conclusion We demonstrated BDL surgery in females leads to hepatic and neurological impairment comparable to male BDL rats (similar intra-group variability). Interestingly, contrary to male BDL vs Shams, body weight and muscle mass does not differ between female BDL and Shams. Since Mmuscle plays an important compensatory role in clearing ammonia during CLD, maintenance of muscle mass in females which could explain the lower blood ammonia levels in female BDL rats compared to male BDL rats. We conclude that this model provides new insights on the impact of sex on the pathogenesis of CLD and HE.

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome observed in chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. AIM: Investigate the synergistic effect of obesity and CLD on the development of neurological impairment in a novel rat model of cirrhosis and obesity. M&M: Animal model of CLD and HE: 5-week bile-duct ligation (BDL) rats and Sham-operated controls, were used. Groups: Obese-BDL and Obese-Sham received high-fat diet (HFD) for 25-days pre-BDL and high-carbohydrate diet (HCD) for 5-weeks post-BDL; Lean-BDL and Lean-Sham received regular-diet (RD) pre-BDL and HCD post-BDL. Body-weight and fat-mass (EchoMRI) were monitored pre-BDL as well as 3- and 5-weeks post-BDL. Behavior: Motor-coordination, motor skill-learning, and muscular-strength were assessed at 3- and 5-weeks post-BDL. Locomotion and anxiety were measured at 5-weeks. Plasma ammonia, liver enzymes, and lipids were measured at 3- and 5-weeks. RESULTS: Before BDL surgery, body-weight and fat-mass of rats on HFD increased compared to rats on RD. 3-week post-BDL, body-weight and fat-mass decreased in Lean-BDL and Obese-BDL vs respective Shams, while at 5-weeks this was only found in Lean-BDL. These parameters were higher in Obese-BDL vs Lean-BDL at 3- and 5-weeks. Plasma ammonia, bilirubin, albumin, ALT, AST, and ALP were impaired in Obese- and Lean-BDL vs respective Shams at 3- and 5-weeks. AST and ALP increased in Obese-BDL vs Lean-BDL at 5-weeks. Elevated HDL-cholesterol and decreased LDL-cholesterol were detected in Obese-BDL and Lean-BDL vs respective Shams at 3- and 5-weeks, while LDL-cholesterol was higher in Obese-BDL vs Lean-BDL at 5-weeks. Total-cholesterol increased in Obese-BDL vs all groups at 5-weeks. At 3 weeks; motor-coordination was reduced in Obese-BDL, but not in Lean-BDL vs respective Shams, while at 5-weeks, motor-coordination decreased in both Lean-BDL and Obese-BDL vs respective Shams, with worse performance in Obese-BDL vs Lean-BDL. At 3-weeks, skill-learning improved in all Shams and Lean-BDL, but not in Obese-BDL; at 5-weeks contrary to Sham-groups, both BDL groups did not improve performance. Muscle-strength decreased in Lean-BDL and Obese-BDL vs respective Shams at 3- and 5-weeks. Hypolocomotion and anxiogenic effects were detected in Obese-BDL, but not in Lean-BDL vs Shams at 5-weeks. CONCLUSION: HFD induces obesity pre-BDL which is maintained post-BDL with a HCD-diet which was accompanied with increase fat-mass and hyperlipidemia. Neurological decline in obese-cirrhotic rats developed earlier and was more severe versus Lean-BDL rats. Besides, some neurological impairments developed in Obese-BDL but not in Lean-BDL. These results suggest a synergistic effect, which accelerates/worsens the disease-associated abnormalities in CLD and HE.

Background: Hyperammonemia associated with chronic liver disease (CLD) is implicated in the pathogenesis of hepatic encephalopathy (HE). The gut is a major source of ammonia (NH3) production that contributes to systemic hyperammonemia in CLD and HE and remains the primary therapeutic target for lowering circulating NH3. As a therapeutic strategy, Escherichia coli Nissle 1917 bacterium (EcN), a well characterized probiotic, was genetically modified to consume and convert NH3 to arginine (SYNARG), and its administration to thioacetamide-treated mice resulted in a significant reduction of NH3 levels1. SYNARG was further modified to synthesize butyrate (SYNARG+BUT), a short-chain fatty acid with anti-inflammatory/anti-oxidant properties, and both strains were tested in an experimental model of cirrhosis and HE, the bile duct ligation (BDL). Methods: One week post surgery, BDL rats were gavaged with SYNARG, SYNARG+BUT (3x1011 CFU/day, BID) or vehicle until they were sacrificed at 3- or 5-weeks along with respective sham controls. Plasma NH3 and liver markers were measured at 3 and 5 weeks. Recognition-memory, motor-coordination, muscle-strength, locomotion and anxiety were assessed in the 5-week BDL groups. Results: BDL significantly increased NH3 over time, with levels of 109.1±9.2µM (Shams 56.7±3.5µM, p<0.001) and 150.2±25.6µM (Shams 58.3±3.0µM, p<0.001) at 3- and 5-weeks, respectively. In addition, plasma liver markers alanine-transaminase, aspartate-transaminase, bilirubin, and gamma-glutamyl transferase were significantly increased in BDL rats at both timepoints while albumin was significantly lowered. As compared to BDL-Veh rats, hyperammonemia was attenuated by SYNARG (103.9±12.3µM) and SYNARG+BUT (110.8±8.5µM) at 5, but not 3 weeks post-surgery, while liver fibrosis (hydroxyproline content) was attenuated at 3, but not 5 weeks post-surgery. None of the circulating liver markers were changed by the treatments at any timepoint. Motor-coordination, muscle-strength, locomotion and anxiety were affected in all BDL groups without protective effect of treatments. Short-term memory (STM) was impaired in BDL-Veh (p<0.001) and BDL-SYNARG (p<0.05) versus Shams, while STM was resolved in BDL-SYNARG+BUT (p<0.05 vs BDL-Veh). Long-term memory (LTM) was impaired in BDL-Veh vs Shams (p<0.05), but BDL-SYNARG and BDL-SYNARG+BUT were protected. Conclusion: EcN, engineered to consume NH3 in the gut and synthesize butyrate, is an effective approach to lower plasma NH3 in a model of cirrhosis and HE. Moreover, the attenuation of hyperammonemia in cirrhotic rats is associated with a protective effect on memory in this model. The therapeutic potential of these engineered EcN strains should be further evaluated in patients with CLD and HE.

Background The impact of sex differences on chronic liver disease (CLD) and hepatic encephalopathy (HE) is unknown. The majority of animals used in research are male since the main difficulty with using female animals is the potential impact of the estrous cycle, increasing intragroup variability. The bile duct ligated (BDL) rat is a well-characterized model of CLD and HE in males which has not been investigated in females. Therefore, we aimed to characterize a female BDL model of CLD and HE and compare to male BDL rats. Material and methods Female rats underwent either BDL (n=8) or Sham (n=8) surgery. After 5 weeks, we assessed estrous cycle phase (by cellular cytology), anxiety (open field test), motor incoordination (rota-rod test) and night-time activity. We also assessed body weight, body composition (MRI), gastrocnemius muscle weight/circumference, grip strength, and ammonia and liver enzymes in plasma. Results from female BDL rats were compared to historical laboratory data from male BDL rats. Results Female BDL rats had increased liver enzymes (ALP (P=0.001) and AST (P<0.0001) (but not ALT)), bilirubin (P<0.0001) and ammonia (p<0.001), and decreased albumin (P<0.0001) compared to female Shams. These results were comparable to male BDL rats except ALT and ammonia which were lower in females (p< 0.01). Female BDL rats did not differ in body weight, muscle circumference/weight and grip strength but had decreased fat mass (p<0.0001), increased lean mass (p<0.005) compared to female shams. Whereas, male BDL rats have decreased fat mass, muscle circumference/weight and grip strength. BDL in female rats induced a dysregulated estrous cycle compared to Sham (increased metestrus phase (p<0.01)). Similar to male BDL rats, female BDL rats had increased anxiety (p<0.005), motor incoordination (p<0.05), and decreased night activity (p<0.05) independent of the estrous cycle phase. Discussion We demonstrated BDL surgery in females leads to hepatic and neurological impairment comparable to male BDL rats (similar intra-group variability). Interestingly, female BDL rats developed unique features. Contrary to male BDL vs Shams, body weight and muscle mass does not differ between female BDL and Shams. Since muscle mass plays an important compensatory role in regulating ammonia levels, this could explain why the increase in blood ammonia levels in female BDL rats (vs. female Shams) was lower compared to male BDL. We expect that this model will provide new insights on the effect of sex differences on the pathogenesis of CLD and HE and help to personalize HE treatment.

Introduction: Hepatic encephalo­pathy (HE) is a neuro­psychiatric syn­drome, a major complication of chronic liver dis­ease (CLD/cirrhosis). The primary cause of hospital admissions for cirrhotic patients is an overt episode of HE. Pre­cipitating factors of HE frequently lead to an in­crease in blood ammonia. Patients who have experienced multi­ple episodes of HE are as­so­ci­ated with persisting neuro­logical complications post-liver trans­plantation. Currently, the impact of HE episodes on neuro­logical in­tegrity is unknown. We hypo­thesize that multi­ple episodes of HE will accelerate and/or in­tensify neuro­logical deterioration. To date, an animal model of episodic HE is lacking. There­fore, our goal was to char­acter­ize an animal model of episodic HE (precipitated with ammonia) and to evalu­ate the impact of cumulative episodes on neuro­logical status in cirrhotic rats. Material and Methods: Animal model of CLD and HE: 6-week bile-duct ligation (BDL) rats, and Sham-operated controls were used. BDL and Sham rats were divided in two groups, episodic and non-episodic. Injection (i.p) of ammonium acetate was used to induce episodes of overt HE (pre-coma; loss of righting reflex) every 4 days starting 3-weeks post-BDL surgery (total 5 episodes). Saline was injected as vehicle for non-episodic groups. Two days following the last HE episode, we assessed motor-coordination (RotaRod), anxiety (elevated plus maze, EPMT), as well as short-term and long-term memory (novel object recognition) in all groups. Upon sacrifice, plasma ammonia was measured. Results: The concentration of ammonia required to induce an episode of overt HE in BDL rats lessened with each subsequent episode, ranging from 7 to 4.5 mmol/kg. Short-term memory (p<0.05) and motor-co­ordi­nation (p<0.05) were impaired in both non-episodic and episodic BDL groups compared to respective Sham-operated controls. Long-term memory impairment (p=0.06) and in­creased anxiety (+60.0%, p<0.05) were exclusively found in episodic BDL rats compared to non-episodic BDL rats. Moreover, there was an in­crease in blood ammonia (+30.4%, p=0.06) in episodic compared to non-episodic BDL rats, suggesting that although episodic-BDL rats recover from each HE episode, baseline (pre-episode) ammonia remain higher than non-episodic BDL rats. Conclusion: Cumulative HE episodes escalate neuro­logical impairments in cirrhotic-BDL rats. Thus, this new episodic HE model repre­sents a good appro­ach to explore the patho­logical mecha­nism arising from multi­ple episodes, as well as further in­ves­tigate whether higher hyperammonemia and/or increased brain sensitivity to ammonia is responsible for more complex neurological manifestations in episodic-BDL rats. More­over, this model is an excellent platform to in­ves­tigate novel therapies to pre­vent/treat episodic HE.

Introduction: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD/cirrhosis). The primary cause of hospital admissions for cirrhotic patients is an overt episode of HE. Precipitating factors of HE are frequently due to increased blood ammonia. Patients with history of multiple episodes of HE experienced persisting neurological complications post-liver transplantation. Nevertheless, the impact of HE episodes on neurological integrity is unknown. We hypothesize that multiple episodes of HE will accelerate and/or intensify neurological deterioration. To date, an animal model of episodic HE is lacking. Therefore, our goal was to characterize an animal model of episodic HE (precipitated with ammonia) and to evaluate the impact of cumulative episodes on neurological status in cirrhotic rats. M&M: Animal model of CLD and HE: 6-week bile-duct ligation (BDL) rats, and Sham-operated controls were used. Ammonium acetate was used to induce HE episodes, every 4 days starting at 3-weeks post-surgery (total 5 episodes). After the last episode, we assessed motor-coordination (RotaRod), anxiety (elevated plus maze), as well as, short-term and long-term memory (novel object recognition). Rats were then sacrificed, and plasma ammonia measured. Results: Short-term memory (p<0.05) and motor-coordination (p<0.05) were reduced in both non-episodic and episodic BDL groups when compared Sham-operated controls. Long-term memory impairment (p=0.06) and increased anxiety (+60.0%, p<0.05) were found only in episodic vs non-episodic BDL rats. Moreover, there was an increase in blood ammonia (+30.4%, p=0.06) in episodic BDL vs non-episodic BDL rats. Conclusion: The induction of HE episodes escalates neurological impairments in cirrhotic rats. Thus, this new episodic HE model represents a good approach to explore the pathological mechanism arising from multiple episodes, as well as further investigate brain sensitivity to ammonia. Moreover, this model is an excellent platform to investigate novel therapies to prevent or treat episodic HE.

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome in chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. Aim: Development of an animal model of cirrhosis and obesity to investigate the synergistic effect of obesity and CLD on the development of neurological impairment and HE. M&M: Model of CLD and HE: 6-week bile-duct ligation (BDL) rats and Sham-controls were used. Inducing obesity: High-fat diet (HFD) was given for 3 weeks before BDL or Sham surgery. Obese-BDL received HFD for 3 weeks pre-BDL and regular diet (RD) for 6 weeks post-BDL; Lean-BDL received RD pre-/post-BDL; Lean-Sham received RD pre-/post-Sham. Recognition memory, motor-coordination, muscular-strength and body-composition (fat vs lean mass) were assessed before, 3 and 6 weeks post-surgery. Results: Before surgery, body weight (BW) and fat mass of rats on HFD (Obese-BDL) were increased vs rats on RD (Lean-BDL, Lean-Sham). 3 weeks post-surgery, BW, fat and lean mass were increased in Obese-BDL vs. Lean-BDL. Long-term memory was reduced in Obese-BDL, but not in Lean-BDL, vs. Lean-Sham. 6 weeks post-surgery, similar to Lean-BDL, Obese-BDL lost BW, fat and Lean mass vs. Lean-Sham. Motor-coordination, forelimb strength and long-term memory were impaired in Obese-BDL vs Lean-BDL or Lean-Sham, whereas hind-limb strength and short-term memory were impaired in both Obese- and Lean-BDL. Conclusion: HFD induces obesity features in healthy non-cirrhotic rats. Such effects are maintained in cirrhotic-BDL rats. Interestingly, some neurological impairments are detected in Obese-BDL but not in Lean-BDL rats, while others are exacerbated. A synergistic effect of obesity and CLD accelerates/worsens the disease-associated abnormalities observed in HE, suggesting more susceptibility to poor neurological performance in obese-induced cirrhotic patients.

Introduction: Hepatic encephalopathy (HE) is a neuropsychiatric disorder, a major complication of chronic liver disease (CLD). Hyperammonemia is central in the pathogenesis of HE as ammonia crosses the blood-brain barrier (BBB) causing toxicity. Glutamine synthetase (GS), an enzyme which removes ammonia during the amidation of glutamate to glutamine, is expressed in liver, muscle and brain. Since liver is responsible for regulating blood ammonia levels, extra-hepatic GS plays an important compensatory role during CLD. However, GS expression in endothelial cells (EC) of the BBB has never been explored. Methods: GS protein and activity was assessed in 1) rat brain microvascular EC (+/- ammonia exposure and plasma from rats with CLD) and 2) isolated cerebral microvessels (CMV) from naïve rats. Results: GS was co-localized with EC in brain of naïve rats. GS protein and activity was detected in CMV and in vitro, but with lower levels compared to brain (p<0.05). EC exposed to ammonia resulted in increased GS activity (p<0.05). However, ECs exposed to plasma from CLD rats resulted in lower GS activity and protein expression compared to controls (p<0.05). Conclusion: We demonstrate for the first time the presence of GS in EC in both in vitro and in vivo. Stimulated by ammonia, GS is however reduced following exposure to plasma from hyperammonemic CLD rats. This suggests other systemic factors such as oxidative stress (present in CLD; Bosoi et al., Free Radic Biol Med, 2012) could hinder GS activity. We speculate a downregulation of GS in the BBB during CLD leads to rapid entry of ammonia into the brain and the development of HE. Hence, upregulating GS in the BBB could become a new therapeutic target for HE. 

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. AIM: Development of an animal model of cirrhosis and obesity to investigate the synergistic effect of obesity and CLD on the development of neurological impairment and HE. M&M: Animal model of CLD and HE: 6-week bile-duct ligation (BDL) rats, as well as Sham-operated controls, were used. Inducing obesity: High-fat diet (HFD) was given for 3 weeks before BDL or Sham surgery. Groups: 1. Obese-BDL rats received HFD for 3 weeks pre-BDL and regular diet (RD) for 6 weeks post-BDL; 2. Lean-BDL rats received RD pre- and post-BDL; 3. Lean-Sham rats received RD pre- and post-Sham surgery. Behaviour: Recognition memory, motor coordination and muscular strength were assessed before surgery, as well as 3 and 6 weeks post-surgery using the novel object recognition, rotarod and grip-strength tests, respectively. Body-composition (echoMRI): Fat vs. lean mass and free water (ascites) were also monitored. RESULTS: Before the surgery, body weight (BW) and fat mass of rats on HFD (Obese-BDL) were increased in comparison to rats on RD (Lean-BDL and Lean-Sham). 3 weeks after surgery, BW, fat mass, lean mass and free water were increased in Obese-BDL rats vs. Lean-BDL rats. Long-term memory was reduced in Obese-BDL, but not in Lean-BDL, vs. Lean-Sham rats. 6 weeks after surgery, similar to Lean-BDL rats, Obese-BDL rats lost BW, fat and Lean mass, while free water increased vs. Lean-Sham rats. Motor coordination, forelimb strength and long-term memory were impaired in Obese-BDL rats in comparison to Lean-BDL or Lean-Sham rats, whereas hind-limb strength and short-term memory were impaired in both Obese- and Lean-BDL rats, compared to Lean-Sham rats. CONCLUSION: HFD induces obesity features in healthy non-cirrhotic rats. Such effects are maintained in cirrhotic-BDL rats. Obesity also accelerates the accumulation of free water in cirrhotic-BDL rats. Interestingly, some neurological impairments are detected in Obese-BDL but not in Lean-BDL rats (long-term memory), while others are exacerbated (motor coordination, forelimb strength). This new animal model of CLD and obesity suggests a synergistic effect, which accelerates and worsens the disease-associated abnormalities observed in CLD and HE. Thus, obesity-induced cirrhosis in patients may result in more complex neurological manifestations, suggesting more susceptibility to poor neurological performance.

BACKGROUND: Malnutrition is the most common complication in patients with chronic liver disease (CLD) and may increase the risk of developing hepatic encephalopathy (HE) as well as affect pa-tients’ functional status and quality of life (QOL). Management strategies focussing on nutritional status in relation to complications of CLD are an unmet clinical need. PURPOSE: The objectives are to: 1) Assess nutri-tional status and its relationship to QOL; 2) Ascer-tain the presence, severity and history of HE; 3) Inquire the relationship of HE and history of HE on the QOL of CLD subjects. METHOD: Observational and cross-sectional study involving 50 patients (hospitalized and outpatients) from the CHUM’s Liver Unit, Montreal, Canada) and 18 controls (non-cirrhotic). All subjects were assessed for: 1) Nutritional Status: Standardized Questionnaire Subjective Global Assessment (SGA); 2) QOL: General questionnaire SF-36 evalu-ating the QOL as perceived by the patient (8 scales: physical functioning (PF), role limitations due to physical health (RP), due to emotional problems (RE), social functioning (SF), bodily pain (BP), vitality (VT), mental health (MH) and general health (GH)); 3) HE: History and presence of covert HE using EncephalApp Stroop test or overt HE using the Clinical Hepatic Encephalopathy Staging Scale.RESULT(S): 50 CLD patients (72% men) of various etiologies (18% NASH, 12% alcoholic, 8% autoim-mune, 6% viral, 12% others and 44% mixed eti-ologies), Child–Pugh (15A, 7B, 18C and 10 N/A), aged 56±12 years and 18 non-cirrhotic patients (33% male, aged 42±15). SGA revealed that 34% of CLD subjects were malnourished. Among mal-nourished CLD patients, 18% were diagnosed with covert or overt HE. CLD malnourished patients had a lower perception of QOL than well-nour-ished CLD patients for all SF-36 scales (p < 0.01). History of HE was associated with poor QOL as CLD patients with a history of HE (36%) showed decreased PF (p = 0.024) and RP (p < 0.01). Com-pared to controls, CLD patients displayed a lower score in PF (p < 0.05) and GH (p < 0.05).CONCLUSION(S): Our data suggest that a subop-timal nutritional status based on SGA negatively affects 6 scales out of 8 of QOL (RP, RE, SF, VT, MH and GH) but is not associated with presence of HE. However, history of HE does impact two scales of QOL (PF and RP). Identifying malnourished CLD patients is of great importance to improve QOL. Interventions to prevent and treat malnutrition in CLD remain a primary need.

BACKGROUND: Muscle wasting (sarcopenia) af-fects 30 to 70% of cirrhotic patients. The presence of sarcopenia may be associated with a worst prog-nosis in cirrhotic patients awaiting and after liver transplantation (LT). To this day, few studies have evaluated and followed muscle mass (in terms of quantity and quality) after LT.PURPOSE: The goal of this study was to assess the association between the evolution of sarcopenia and the prognosis of cirrhotic patients before and after LT.METHOD: In total, 94 cirrhotic patients who un-derwent LT at the Montreal University Hospital Center – Liver Unit were included. Sarcopenia was assessed at the third lumbar level vertebrae using a computed tomography scan (CT-scan). The diag-nostic of sarcopenia was based on previously estab-lished sex-specific cut-off values of skeletal muscle index. Patients were classified into two groups: 1) persistent or newly developed sarcopenia after LT (Sarc+); 2) resolved sarcopenia or absence of sarcope-nia before and after LT (Sarc–). Muscle quality (myo-steatosis) was assessed by calculating intramuscular adipose tissue content. The prognostic factors were collected 6 months before and during 1 year after LT through medical records and included the num-ber of complications, the episodes of infections, the length of stay, and the frequency of readmissions.RESULT(S): Sarcopenia persisted or was newly de-veloped (Sarc+) in 62% of the patients (n = 58). It remained absence or was resolved after LT in 38% of the patients (n = 35). Muscle quality was significantly decreased post-LT (p = 0.034). The group Sarc+ ex-perienced more complications pre-LT (p = 0.012) and post-LT (p < 0 .001), infections post-LT (p = 0.006) and readmissions (p = 0.048) compared to the group Sarc−. The length of stay was longer for the group Sarc+ as opposed to the group Sarc− (p < 0 .001).CONCLUSION(S): Persistent and newly developed sarcopenia after LT appear to have negative out-comes on the prognosis of patients. Interventional strategies to optimize, increase or preserve muscle mass could help to improve post-operative recov-ery as well as the quality of life in patients who have undergone LT.

Background: The liver plays a major role in regulating ammonia levels in the blood. Therefore, in liver disease, the loss of hepatic function leads to hyperammonemia and consequently hepatic encephalopathy (HE). Ammonia-lowering strategies remain the mainstay therapeutic strategy for HE. Ammonia, both as an ion (NH4+) and gas (NH3), readily crosses all plasma membranes, including the blood-brain barrier (BBB): the interface between the blood and the brain. Since ammonia is a natural toxin, we hypothesize endothelial cells of the BBB have the capacity to metabolize ammonia to protect the brain from ammonia toxicity. Glutamine synthetase (GS), is an enzyme which in the process of amidating glutamate to glutamine removes ammonia is expressed in liver, muscle and brain (primarily in astrocytes) but has never been thoroughly explored in the BBB. The aim of this study was to assess the presence of GS in endothelial cells of the BBB. Methods: Using brain primary microvascular endothelial cells (ECs) and isolated cerebral microvessels (CMV) from the frontal cortex of naïve rats, we assessed GS’s activity and mRNA and protein expression of GS by rtPCR and western blot (brain used as positive control). We also assessed GS expression in brain slices of naïve rats by immunofluorescence (co-localized with endothelial cell marker caveolin-1). In addition, to understand the effect of liver disease on GS, we exposed ECs to plasma from bile-duct ligated (BDL) rats (model of chronic liver disease) and sham-operated controls , as well as 1mM of ammonia chloride and 10μM of hydrogen peroxide as oxidative stress. Results: In vitro ECs and in vivo CMVs both expressed GS mRNA, protein and activity. Immunofluorescence showed GS colocalized with caveolin-1, further proving the presence of GS in endothelial cells of the BBB. The treatment with ammonia increased the activity of GS, while treatment with oxidative stress reduced its activity (p<0.05). ECs exposed to plasma from BDL rats reduced GS activity and protein expression compared with plasma from sham controls (p<0.01). Conclusion: These results demonstrate for the first time that GS is present in ECs in both in vivo and in vitro. Interestingly, ammonia stimulates GS in endothelial cells, whereas oxidative stress inhibits GS activity. Furthermore, GS activity is decreased in the presence of plasma from cirrhotic rats, possibly due to the presence of systemic oxidative stress in BDL rats. We speculate that downregulation of GS allows for faster and easier entry of ammonia into the brain and therefore may increase the risk of HE. We anticipate that upregulating GS in ECs of the BBB could become a new therapeutic target for HE.

Introduction : La sarcopénie affecte jusqu’à 70% des patients atteints d’une maladie hépatique chronique (cirrhose). Sa présence a été associée à une qualité de vie détériorée. Par ailleurs, elle pourrait influencer le pronostic des patients cirrhotiques avant et après la transplantation hépatique (TH), seul traitement curatif pour la cirrhose à ce jour. Peu d’études ont étudié l’évolution de la sarcopénie après la TH. Le but de cette étude était d’évaluer l’évolution de la sarcopénie et son association avec le pronostic des patients cirrhotiques pré- et post-TH. Méthodes : L’évaluation de la masse musculaire a été effectuée chez 94 patients du département d’hépatologie du CHUM ayant reçu la TH entre le 5 juin 2012 et le 30 avril 2017. Elle était évaluée en utilisant l’index musculaire squelettique lequel est basé sur l’analyse de l’examen radiologique de tomodensitométrie au niveau de la 3e vertèbre lombaire. Par la consultation des dossiers médicaux, les critères de pronostic étaient évalués durant l’année suivant la TH et comprenaient le nombre de complications, les épisodes d’infection, la durée de l’hospitalisation et la fréquence des réadmissions. Résultats : La sarcopénie a persisté ou est apparue (Sarc+) chez 62% des patients (n=58) alors qu’elle a régressé ou est demeurée absente (Sarc-) chez 38% des patients (n=35). Le groupe Sarc+ a eu davantage de complications avant la TH (p=0,012) et après la TH (p<0,001) et d’infections après la TH (p=0,006) par rapport au groupe Sarc-. La durée de l’hospitalisation était aussi prolongée chez le groupe Sarc+ comparativement au groupe Sarc- (p<0,001). Conclusion : La sarcopénie persistante ou nouvellement développée telle qu’évaluée jusqu’à 1 an après la TH est associée à un mauvais pronostic, particulièrement en période post-TH. La mise en place de stratégies d’intervention pour préserver ou même augmenter la masse musculaire pourrait aider à améliorer le pronostic des patients suite à la TH. Bourses octroyées par le Département de nutrition et la Faculté de médecine de l’Université de Montréal

Problématique : Au Canada, la prévalence de la maladie hépatique connaît une croissance exponentielle. L’une des complications les plus prévalentes y étant associée est la malnutrition, qui affecte la qualité de vie des patients par l’augmentation des risques de nombreuses complications. Objectif : L’objectif général est d’évaluer l’impact bénéfique potentiel du Guide de nutrition pour la cirrhose, un document éducatif basé sur des données probantes et sur l’expérience de patient-partenaire, qui traduit les lignes directrices en matière de nutrition et cirrhose. Les objectifs spécifiques sont d’évaluer l’état nutritionnel, la qualité de vie reliée à la santé et la fonction hépatique en plus de déterminer les connaissances en nutrition des patients cirrhotiques après l’implantation du Guide. Méthodologie : Nous visons l’inclusion de 132 patients visitant la clinique externe d’hépatologie du CHUM. Les patients seront rencontrés par une nutritionniste, qui évaluera l’état nutritionnel, la qualité de vie, la fonction hépatique et leurs connaissances en nutrition. Le Guide leur sera ensuite enseigné et fourni pour 12 semaines, pendant lesquelles un suivi téléphonique sera réalisé à chaque deux semaines. Au terme des 12 semaines, les mêmes évaluations seront réalisées par la nutritionniste. Ces patients seront comparés à un groupe contrôle d’environ 40 sujets cirrhotiques recevant des conseils nutritionnels « habituels », mais n’ayant pas accès au Guide. Résultats attendus : Les patients ayant eu accès au Guide devraient voir une amélioration au niveau des paramètres mesurés. Discussion : Les résultats de cette étude devraient permettre d’optimiser la qualité des soins chez les gens souffrant de maladies chroniques du foie.

Background and aims:Acute liver failure (ALF) is associated withsignificant mortality. Failure to identify non-survivors results inpreventable deaths, while misclassifying prospective survivors maylead to unnecessary transplants (LT). Liver-type fatty acid bindingprotein (FABP1) is a 15 kDa protein expressed in hepatocytes. It haspreviously been demonstrated to improve prognostic discriminationin acetaminophen (APAP)-induced ALF but has not been investigatedin other etiologies of ALF. Our primaryaim was too determine if serialFABP1 levels (early; admission or late; day 3–5) are associated with21-day transplant-free survival in non-APAP ALF. Method:FABP1 was measured in serum samples from 384 ALFpatients (n = 88 transplant-free survivors (TFS), n = 296 died/LT∼NTFS) using solid-phase enzyme-linked immunosorbent assay(ELISA) and analysed with US ALFSG registry data.Results:Of 384 patients, etiologies of ALF included autoimmunehepatitis (AIH, n = 125), drug-induced liver injury (DILI, n = 141) andHepatitis B (n = 118). Overall, 177 (46%) ALF patients received LT.Transplant-free survivors (n = 88) were less likely to requiremechanical ventilation (21 vs. 66%), vasopressors (10% vs. 35%) andor have Grade III/IV hepatic encephalopathy (30% vs. 73%, p < 0.0001for all) compared with patients who died/required LT. FABP1 levelswere significantly lower in TFS patients at day 3–5 (TFS 54 vs. NTFS 66 ng/ml; p = 0.049; see Figure) but not admission (TFS 96 vs. NTFS87 ng/ml; p = 0.67). After adjusting for significant covariates,increased FABP1 levels at late time points (day 3–5) were significantlyassociated with worse outcomes (death/LT) in AIH patients (LogFABP1 Odds Ratio (OR) 3.93 (1.50–10.32), P = 0.0055; AUROC 0.89).Increased late FABP1 was associated with worse outcomes in HBV(Log FABP1 OR 1.85 (0.96–3.59), P = 0.068; AUROC 0.82) and DILI (LogFABP1 OR 1.36 (0.97–1.91), P = 0.079; AUROC 0.72), but these werenot statistically significant after adjusting for covariates. Similarly,FABP1 on admission was not significant (adjusted p > 0.15 for allsubgroups). Conclusion:This is the first report of FABP-1 in non-APAP-ALF. Usedin combination with existing prognostic scores, FABP1 may poten-tiallyhelp identify ALF patients with higher recovery potential at latertime points after a period of organ support.

Background and aims:Musclewasting (sarcopenia) affects 30 to 70%of cirrhotic patients. The presence of sarcopenia may be associatedwith a worst prognosis in cirrhotic patients awaiting and after livertransplantation (LT). To this day, few studies have evaluated andfollowed muscle mass (in terms of quantity and quality) after LT.The goal of this study was to assess the association between theevolution of sarcopenia and the prognosis of cirrhotic patients beforeand after LT.Method:In total, 94 cirrhotic patients who underwent LT at theMontreal University Hospital Center-Liver Unit were included.Sarcopenia was assessed at the third lumbar level vertebrae using acomputed tomography scan (CT-scan). The diagnostic of sarcopeniawas based on previously established sex-specific cut-off values ofskeletal muscle index. Patients were classified into two groups: (1)persistent or newly developed sarcopenia after LT (Sarc+); (2)resolved sarcopenia or absence of sarcopenia before and after LT(Sarc-). Muscle quality (myosteatosis) was assessed by calculatingintramuscular adipose tissue content. The prognostic factors werecollected 6 months before and during 1 year after LT through medicalrecords and included the number of complications, the episodes ofinfections, the length of stay, and the frequency of readmissions.Results:Sarcopenia persisted or was newly developed (Sarc+) in 62%of the patients (n = 58). It remained absence or was resolved after LTin 38% of the patients (n = 35). Muscle quality was significantlydecreased post-LT (p = 0.034). The group Sarc+ experienced morecomplications pre-LT (p = 0.012) and post-LT (p < 0.001), infectionspost-LT (p = 0.006) and readmissions (p = 0.048) compared to thegroup Sarc-. The length of stay was longer for the group Sarc+ asopposed to the group Sarc- (p < 0.001).Conclusion:Persistent and newly developed sarcopenia after LTappear to have negative outcomes on the prognosis of patients.Interventional strategies to optimize, increase or preserve musclemass could help to improve post-operative recovery as well as thequality of life in patients who have undergone LT.

Loss of muscle mass and strength is common in cirrhosis and increases the risk of hyperammonemia and hepatic encephalopathy. Resistance training optimizes muscle mass and strength in several chronic diseases. However, the beneficial effects of resistance training in cirrhosis remains to be investigated. Bile duct ligated (BDL)-rats develop chronic liver disease, hyperammonemia, reduced muscle mass and strength. Our aim was to test the effects of resistance training on muscle mass, function and ammonia metabolism in BDL-rats. A group of BDL-rats underwent a progressive resistance training program and a group of non-exercise BDL-rats served as controls. Resistance training comprised of ladder climbing with a progressive increase in carrying weights attached to the tail. Training was performed five days a week during four weeks. Muscle strength and body composition were assessed using grip strength and EchoMRI. Weight and circumference of the gastrocnemius muscle (normalized to bodyweight), plasma ammonia and glutamine synthetase protein expression and activity were assessed. BDL+exercise rats had significantly larger gastrocnemius circumference compared to non-exercise BDL-rats: ratio 0.082 vs. 0.075 (p<0.05). Gastrocnemius muscle weight was higher in exercisers than controls: 0.006 vs. 0.005 (p<0.05). A tendency towards a lower plasma ammonia in the exercise group compared to controls was observed (p=0.10). There were no differences in lean body mass, GS protein expression and activity between the groups. Resistance training in rats with chronic liver disease beneficially effects muscle mass and strength. The effects were followed by non-significant reduction in blood ammonia, however a tendency was observed. This article is protected by copyright. All rights reserved.

Introduction: Sarcopenia affects up to 70% of patients suffering from chronic liver disease (cirrhosis). The presence of sarcopenia may influence the prognosis of cirrhotic patients before and after liver transplantation (LT). Few studies have assessed the evolution of sarcopenia in LT. The goal of this study was to follow the evolution and assess the impact of sarcopenia on the prognosis of cirrhotic patients before and after LT. Methods: Skeletal muscle index (SMI) was calculated from cross‐sectional muscle area at the third lumbar level (L3) on computed tomography (CT). The following CT‐scans were analysed: before LT + before discharge and/or nearest 1‐year post‐LT. Sarcopenia was defined using previously published cutoffs based on gender. The association of sarcopenia with prognostic factors (mortality, hospital stay, infections, readmissions) was assessed in cirrhotic patients who underwent LT. Results: Thus far, the average SMI before LT of sarcopenic and non‐sarcopenic patients were 40.3±5.3 cm2/m2 and 58.7±13.7 cm2/m2, respectively. The correlation of SMI with length of hospital stay, infections, and readmissions were high (rspearman = −0.714 p = 0.071), moderate (rspearman = −0.598 p = 0.156), and low (rspearman = −0.386 p = 0.393). Conclusions: Preliminary results indicate that low muscle mass before LT tends to be associated with prolonged hospitalization. As we analyse the remaining data, the strength of the relationship between sarcopenia and the prognosis in LT will help better guide patient care.

Introduction : La sarcopénie affecte jusqu’à 70% des patients atteints d’une maladie hépatique chronique (cirrhose). Sa présence a été associée à une qualité de vie détériorée. Par ailleurs, elle pourrait influencer le pronostic des patients cirrhotiques avant et après la transplantation hépatique (TH), seul traitement curatif pour la cirrhose à ce jour. Peu d’études ont étudié l’évolution de la sarcopénie après la TH. Le but de cette étude était d’évaluer l’évolution de la sarcopénie et son association avec le pronostic des patients cirrhotiques pré- et post-TH. Méthodes : L’évaluation de la masse musculaire a été effectuée chez 94 patients du département d’hépatologie du CHUM ayant reçu la TH entre le 5 juin 2012 et le 30 avril 2017. Elle était évaluée en utilisant l’index musculaire squelettique lequel est basé sur l’analyse de l’examen radiologique de tomodensitométrie au niveau de la 3e vertèbre lombaire. Par la consultation des dossiers médicaux, les critères de pronostic étaient évalués durant l’année suivant la TH et comprenaient le nombre de complications, les épisodes d’infection, la durée de l’hospitalisation et la fréquence des réadmissions. Résultats : La sarcopénie a persisté ou est apparue (Sarc+) chez 62% des patients (n=58) alors qu’elle a régressé ou est demeurée absente (Sarc-) chez 38% des patients (n=35). Le groupe Sarc+ a eu davantage de complications avant la TH (p=0,012) et après la TH (p<0,001) et d’infections après la TH (p=0,006) par rapport au groupe Sarc-. La durée de l’hospitalisation était aussi prolongée chez le groupe Sarc+ comparativement au groupe Sarc- (p<0,001). Conclusion : La sarcopénie persistante ou nouvellement développée telle qu’évaluée jusqu’à 1 an après la TH est associée à un mauvais pronostic, particulièrement en période post-TH. La mise en place de stratégies d’intervention pour préserver ou même augmenter la masse musculaire pourrait aider à améliorer le pronostic des patients suite à la TH. Bourses octroyées par le Département de nutrition et la Faculté de médecine de l’Université de Montréal

Introduction: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of liver disease. The prevalence of the development of cirrhosis is similar in both males and females. The use of animal models of chronic liver disease contributes greatly to the understanding of the mechanisms of HE. To date, fundamental and pre-clinical research in HE has not been investigated in female animals. Since behavioral tests used to assess HE in rats are influenced by the female’s reproductive cycle (the estrous cycle), the aims of this pilot project are 1) to evaluate the estrous cycle, 2) assess degree of liver failure and 3) investigate the neuro phenotype of female bile duct ligated (BDL) rats, (a model of HE) compared to female SHAMs. Methods and results: 6 weeks bile duct ligated (BDL) female rats (N=6) had an increase in body weight, food intake and lean mass (a trend for lower fat mass (p=0.066)), with impaired liver function (p=0.009), dysregulated estrous cycle (measured by daily vaginal cytology), and impaired short-term memory (p=0.057) vs SHAM operated controls (N=4). Historical data from male BDLs showed similar liver and memory impairment, but a decrease in the body weight and food intake vs male SHAMs. Compared to male BDL, female BDL rats showed a similar degree of liver disease as well as short-term memory impairment, which was evident in the diestrous phase. However, a higher increase in body weight and food intake was found in female vs male BDL. A dysregulated estrous cycle was found in female BDL, however, all 4 phases of the cycle were completed. Discussion: These preliminary results demonstrate that there are potential differences between both male and female BDL rats and thus merit to be addressed.

Hepatic encephalopathy (HE) is a common and potentially severe complication of liver failure. HE is related to impaired quality of life. The pathogenesis of HE is linked with gut-derived ammonia (NH3) therefore treatment aim to reduce the blood level of NH3. The standard care of HE is Lactulose, a non-absorbable disaccharide. Nonetheless, patient observance is poor due to some uncomfortable side-effect. Among new therapies that have arisen this past decade, Rifaximin is a potent candidate. The aim of this study is to assess the efficiency of Rifaximin in reducing plasma NH3 and ameliorate the HE in a murine bile duct model. Three weeks after BDL surgery, BDL and SHAM-operated rats were sorted into five groups according to their treatments : SHAM-vehicle, BDL-vehicle, BDL-Lactulose, BDL-Rifaximin, BDL-Lactulose+Rifaximin. Treatment was given by gavage for 3 weeks. Survival, body-weight, food consumption and body composition were assess every week during the six weeks of the study. Behavioral analysis was conduct to assess the HE status. At sacrifice, brain water was measured to assess potential brain edema and plasma sample was taken to measure NH3 and hepatic biochemistry parameters. No difference was seen in the survival, growth pattern, food consumption or body composition between BDL-groups. No difference was seen in the performance during EPM, OFT, Rotarod, NOR or night activity. No difference was seen in brain water between SHAM or BDL groups. Surprisingly, NH3 level was increase in all but BDL-vehicle compare to SHAM. The biochemistry parameters confirm the establishment of cirrhosis in BDL groups compare to SHAM. Overall, this study didn’t present strong, reliable and enough data to conclude on the efficacy of Rifaximin as sole treatment in the context of HE. Some results fail to reach significance probably because of the low number of animals. Future direction on this project will aim to : 1) increase the antibiotic dose; 2) reduce the duration of the model to five weeks; 3) trigger an episode of HE by injecting a dose of NH3 before treating the rats.

Introduction: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (CLD; cirrhosis) and may increase the risk of developing other complications including hepatic encephalopathy (HE). Malnutrition in cirrhosis may also affect patient’s functional status and health-related quality of life (HRQOL). Management strategies focussing on nutritional status in relation to complications of cirrhosis are an unmet clinical need. We hypothesize that sub-optimal nutritional status in cirrhotic patients increases the risk of developing HE and decreases HRQOL. Objectives: The primary goal is to evaluate the impact of nutritional status on health-related quality of life in cirrhotic patients. The secondary goal is to ascertain the presence of HE and examine its relationship with nutritional status and HRQOL. Methods: Hospitalized and outpatients with cirrhosis as well as non-cirrhotic (NC) patients were assessed for 1) Nutritional status (SGA); 2) HE; 3) HRQOL (SF-36). Results: 50 cirrhotic patients (72% men) of various etiologies as well as 18 NC patients (33% men) were included. SGA analysis revealed that 34% of cirrhotic patients were malnourished whereas 12% of cirrhotic patients were diagnosed with HE at time of recruitment and 37% had a history of HE. Among malnourished CLD patients, 18% were diagnosed with HE. CLD malnourished patients showed a decreased HRQOL compared to well-nourished CLD patients (p<0,01). Moreover, HE had an impact on HRQOL as cirrhotic patients with a history of HE episode(s) showed decreased physical functioning (p=0,024) and role limitations due to physical health (p=0,002). Interestingly, when compared to NC patients, CLD patients displayed a lower score in physical functioning (p<0,0001) and general health (p=0,027). Conclusion: Our data suggest that poor nutritional status and history of HE episode(s) do negatively influence HRQOL in cirrhotic patients. Significance: Our study provides important results in order to empower the field of dietitics to actively engage in malnutrition management in cirrhosis.

Hepatic encephalopathy (HE) is a common and debilitating neuropsychiatric complication of liver disease characterized by a constellation of symptoms, including cognitive, psychiatric and motor disturbances. One of the causes of liver disease is alcoholic cirrhosis, which can induce acquired cerebellar degeneration syndrome, atrophy of the cerebellum producing symptoms of ataxia and motor difficulties. In the literature, very few experimental studies concern the role of alcohol on the development of HE. Here we examine the effects of ethanol on bile duct ligation (BDL) rats, a HE model, using a variety of behavioral tasks on motor coordination, open field behavior and memory. BDL rats were subjected to double ligation on the common bile duct with dissection between the ligatures, sham-operated rats underwent the same surgery except for ligation. We first effectuated a dose-response study (N=4-5) in BDL rats to determine the optimal dosage regimen of ethanol. 7 days after surgery, BDL rats were given ethanol by intragastric gavage with 1, 2, 4, 6 and 8 g/kg or saline over a 4-weeks period. Crews Scale and blood ethanol concentration were checked weekly. The accelerating rotarod was used to assess motor coordination. Then the dose regimen of intermittent exposure of 2X3g/kg 3h apart 5 days per week during 4 weeks was chosen to further elucidate the evolution of neurological deficits in both BDL rats and their sham operated controls. The behavioral assessments were performed at 7, 14, 21, 28 and 35 days, one day after blood ethanol concentration dropped to zero of each treatment cycle. Rats were assigned to the following groups (N=9-10): Sham + saline, Sham + ethanol, BDL + saline, BDL + ethanol. The baseline of rotarod performance and gait analysis parameters (at 7 days) showed there were no difference among groups before ethanol gavage. However, BDL + ethanol group rats had gradually impaired coordination performance and motor activity, contrary to those of Sham+ ethanol group who improved their performance gradually by learning. No significant differencet was observed in gait analysis. In addition, blood ethanol concentration over time showed a different metabolism mode in BDL compared with that of Sham + ethanol rats. The changes in coordination performance of BDL+ethanol rats might be associated with some biomolecular changes in the brain. The fact that the front cortex water content in these rats slightly increased as well as the weight of cerebellum reduced suggests that neuroinflammation and cerebellar atrophy might be involved in. Results of the current study indicate heavy alcohol ingestion impairs gradually motor coordination during cirrhosis. BDL rats treated with alcohol allowed perform studies on motor alterations in less than 5 weeks, will be an efficient animal model for the study of HE induced by ethanol and for the search of new treatment strategies.

Problématique: La sarcopénie (perte de masse et de fonction musculaires) affecte 30 à 70% des patients atteints de maladie hépatique chronique (cirrhose). Un Canadien sur 4 souffrirait de maladie hépatique. Chez les patients cirrhotiques, la présence de la sarcopénie avant et après la transplantation hépatique (TH) serait associée à un mauvais pronostic. Objectif : Le but général de cette étude rétrospective en cours est de déterminer, chez les patients cirrhotiques, la prévalence de la sarcopénie avant la TH ainsi que son impact sur le pronostic après la TH. Méthodologie : Notre étude vise l’inclusion de 100 patients cirrhotiques de diverses étiologies. L’évaluation de la masse musculaire avant la TH s’effectue en utilisant l’index musculaire squelettique lequel est basé sur l’analyse de l’examen radiologique de tomodensitométrie (CT-scan) au niveau de la 3e vertèbre lombaire. La durée de l’hospitalisation, la fréquence d’infections et le nombre de réadmissions durant la première année post-TH sont également recueillis par la consultation des dossiers médicaux. Résultats attendus: Nous anticipons que la sarcopénie soit répandue chez les patients cirrhotiques à l’étude. Sa présence pourrait être associée à une durée d’hospitalisation prolongée, à de fréquentes infections et à des réadmissions récurrentes. Discussion : Une prise en charge de la sarcopénie pourrait s’avérer primordiale si sa présence influence le pronostic des patients suite à la TH.

Hepatic encephalopathy (HE) is a common and severe complication of liver failure. The pathogenesis of HE is linked with gut-derived ammonia (NH3). The standard care for patient experiencing episodes of HE is lactulose but observance is poor due to uncomfortable side-effects. Rifaximin is a potent candidate but there is no clinical study that assess its efficiency solely. This study aim to assess, in a bile-duct ligation (BDL) model of HE, the efficiency of rifaximin to reduce plasma NH3 and ameliorate HE status. 3 wks after BDL surgery, all animals were sorted in 5 grps: SHAM-Veh, BDL-Veh, BDL-Lac, BDL-Rif, BDL-Lac+Rif. Ttm was given by gavage for 3 wks with vehicle, lactulose, rifaximin and the combination of both ttm. Survival, body-weight, food consumption and body composition was assess every wk. During the ttm, behavioral analysis was done to assess the HE status, including OFT, EPM, Rotarod, NOR and night activity. At the end of the study, brain water was measured and plasma sample was taken. No difference was seen in the survival, growth, food consumption or body composition between BDL-grps. In the last wk the free water was increased in all BDL rats. No difference was seen in any grps regarding behavioral tests nor was any evidence of brain edema. NH3 level was increased in BDL treated with either lactulose or rifaximin compare to SHAM but surprisingly not with vehicle. The biochemistry parameters confirm the onset of cirrhosis in BDL grps. This study don’t present strong, reliable and sufficient data to conclude on the efficacy of rifaximin. Future direction will aim to increase the dose of drug; reduce the duration of the model; trigger an episode of HE before ttm.

Problématique: La sarcopénie (perte de masse et de fonction musculaires) affecte 30 à 70% des patients atteints de maladie hépatique chronique (cirrhose). Un Canadien sur 4 souffrirait de maladie hépatique. Chez les patients cirrhotiques, la présence de la sarcopénie avant et après la transplantation hépatique (TH) serait associée à un mauvais pronostic. Objectif : Le but général de cette étude rétrospective en cours est de déterminer, chez les patients cirrhotiques, la prévalence de la sarcopénie avant la TH ainsi que son impact sur le pronostic après la TH. Méthodologie : Notre étude vise l’inclusion de 100 patients cirrhotiques de diverses étiologies. L’évaluation de la masse musculaire avant la TH s’effectue en utilisant l’index musculaire squelettique lequel est basé sur l’analyse de l’examen radiologique de tomodensitométrie (CT-scan) au niveau de la 3e vertèbre lombaire. La durée de l’hospitalisation, la fréquence d’infections et le nombre de réadmissions durant la première année post-TH sont également recueillis par la consultation des dossiers médicaux. Résultats attendus: Nous anticipons que la sarcopénie soit répandue chez les patients cirrhotiques à l’étude. Sa présence pourrait être associée à une durée d’hospitalisation prolongée, à de fréquentes infections et à des réadmissions récurrentes. Discussion : Une prise en charge de la sarcopénie pourrait s’avérer primordiale si sa présence influence le pronostic des patients suite à la TH.

Background: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (CLD; cirrhosis) and may increase the risk of developing other complications including hepatic encephalopathy (HE). Malnutrition in cirrhosis may also affect patient’s functional status and health-related quality of life (HRQOL). Management strategies focussing on nutritional status in relation to complications of cirrhosis are an unmet clinical need. We hypothesize that sub-optimal nutritional status in cirrhotic patients increases the risk of developing HE and decreases HRQOL. Purpose: The primary purpose is to evaluate the impact of nutritional status on health-related quality of life in cirrhotic patients. The secondary purpose is to ascertain the presence of hepatic encephalopathy and examine its relationship with nutritional status and HRQOL. Method: Hospitalized and outpatients (CHUM’s Liver Unit, Montreal, Canada) with cirrhosis as well as non-cirrhotic (NC) patients were assessed for 1) Nutritional status (Subjective Global Assessment (SGA)); 2) HE (presence or history); 3) HRQOL (Short-Form-36 (SF-36) questionnaire). Results: 50 cirrhotic patients (72% men) of various etiologies, Child-Pugh (15A, 7B, 18C, 10 unknown), mean age 56±12 as well as 18 NC patients (33% men, mean age 42±15) were included. SGA analysis revealed that 34% of cirrhotic patients were malnourished whereas 12% of cirrhotic patients were diagnosed with HE at time of recruitment and 37% had a history of HE. Among malnourished CLD patients, 18% were diagnosed with HE. CLD malnourished patients showed a decreased HRQOL compared to well-nourished CLD patients (p<0,01). Moreover, HE had an impact on HRQOL as cirrhotic patients with a history of HE episode(s) showed decreased physical functioning (p=0,024) and role limitations due to physical health (p=0,002). Interestingly, when compared to NC patients, CLD patients displayed a lower score in physical functioning (p<0,0001) and general health (p=0,027). Conclusion: Our data suggest that poor nutritional status does negatively influence HRQOL in cirrhotic patients but is not associated with HE. However, history of HE episode(s) does impact on HRQOL among this population. Therefore, identifying malnourished patients is of great importance and interventions for treating malnutrition remains an unmet clinical need.

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. AIM: Development of an animal model of cirrhosis and obesity to investigate the synergistic effect of obesity and CLD on the development of neurological impairment and HE. M&M: Animal model of CLD and HE: 6-week bile-duct ligation (BDL) rats, as well as Sham-operated controls, were used. Inducing obesity: High-fat diet (HFD) was given for 3 weeks before BDL or Sham surgery. Groups: 1. Obese-BDL rats received HFD for 3 weeks pre-BDL and regular diet (RD) for 6 weeks post-BDL; 2. Lean-BDL rats received RD pre- and post-BDL; 3. Lean-Sham rats received RD pre- and post-Sham surgery. Behaviour: Recognition memory, motor coordination and muscular strength were assessed before surgery, as well as 3 and 6 weeks post-surgery using the novel object recognition, rotarod and grip-strength tests, respectively. Body-composition (echoMRI): Fat vs. lean mass and free water (ascites) were also monitored. RESULTS: Before the surgery, body weight (BW) and fat mass of rats on HFD (Obese-BDL) were increased in comparison to rats on RD (Lean-BDL and Lean-Sham). 3 weeks after surgery, BW, fat mass, lean mass and free water were increased in Obese-BDL rats vs. Lean-BDL rats. Long-term memory was reduced in Obese-BDL, but not in Lean-BDL, vs. Lean-Sham rats. 6 weeks after surgery, similar to Lean-BDL rats, Obese-BDL rats lost BW, fat and Lean mass, while free water increased vs. Lean-Sham rats. Motor coordination, forelimb strength and long-term memory were impaired in Obese-BDL rats in comparison to Lean-BDL or Lean-Sham rats, whereas hind-limb strength and short-term memory were impaired in both Obese- and Lean-BDL rats, compared to Lean-Sham rats. CONCLUSION: HFD induces obesity features in healthy non-cirrhotic rats. Such effects are maintained in cirrhotic-BDL rats. Obesity also accelerates the accumulation of free water in cirrhotic-BDL rats. Interestingly, some neurological impairments are detected in Obese-BDL but not in Lean-BDL rats (long-term memory), while others are exacerbated (motor coordination, forelimb strength). This new animal model of CLD and obesity suggests a synergistic effect, which accelerates and worsens the disease-associated abnormalities observed in CLD and HE. Thus, obesity-induced cirrhosis in patients may result in more complex neurological

The liver plays a major role in regulating ammonia levels in the blood. Therefore, in liver disease the loss of hepatic function leads to hyperammonemia and increased brain ammonia and consequently hepatic encephalopathy (HE). Ammonia-lowering strategies remain the mainstay therapeutic strategy. Ammonia, both as an ion (NH4+) and gas (NH3), easily crosses all plasma membranes, including the blood brain barrier (BBB); the interface between the blood and the brain. Glutamine synthetase (GS), an enzyme which in the process of amidating glutamate to glutamine removes ammonia, plays an important compensatory role during liver disease. GS is expressed in muscle and brain (primarily in astrocytes) but has never been thoroughly explored in the BBB. Therefore, the aim is to evaluate GS expression in endothelial cells of the BBB. Using primary rat brain microvascular endothelial cells (ECs), the presence of GS was assessed using rtPCR, western blot, immunohistochemistry and activity assay. Furthermore, we isolated cerebral microvessels (CMV) from the frontal cortex of naïve rats and measured GS expression by western blot using brain lysates as positive control and by immunohistochemistry (co-localized with caveolin-1 (marker for ECs). In addition, to understand the effect of ammonia on GS, ECs were exposed to 1mM of ammonia chloride for 48h. Finally, ECs were subjected to plasma from bile-duct ligated (BDL) rats (model of chronic liver disease) or sham-operated controls. We have characterized this BDL model and found both systemic oxidative stress and inflammation, in addition to hyperammonemia. ECs expressed GS mRNA, protein and activity. However, expression of GS was lower compared to brain lysate control samples (p<0.05). GS expression in CMV showed similar results to brain but GS activity was less (p<0.05). Using immunohistochemistry, GS was detected in ECs and in vessels of brain from naïve rats. When cells were submitted to ammonia, an increase in GS activity was demonstrated (p<0.05). However, when exposed to conditioned medium from BDL rats, GS was decreased when compared to sham-operated controls (p<0.01). These results demonstrate for the first time that GS is present in ECs in both in vivo and in vitro. The lower expression of the enzyme compared to that found in the brain, could explain why GS has never been reported in these cells. Interestingly, ammonia stimulates GS in endothelial cells, but its activity is decreased in the presence of other pathogenic factors in plasma from cirrhotic rats such as oxidative stress and inflammation. We speculate that a downregulation of GS allows for a faster and easier entry of ammonia into the brain and therefore may be implicated in the pathogenesis of HE. We anticipate increasing GS in ECs of the BBB could become a new therapeutic target for HE

La perte de masse musculaire et la malnutrition sont les complications les plus fréquentes de la maladie hépatique chronique (cirrhose). L’encéphalopathie hépatique (EH; désordre neuropsychiatrique) est une autre complication sérieuse observée chez 80% des patients cirrhotiques, qui pourrait être une conséquence de la perte de masse musculaire. Les myokines, dont « Brain-derived neurotrophic factor » (BDNF), sont des cytokines libérées par le muscle lors de la contraction musculaire exerçant plusieurs fonctions physiologiques bénéfiques. Leurs sécrétions impliquent la production d’un co-activateur transcriptionnel, le « Peroxisome proliferator-activated receptor coactivator-1alpha » (PGC-1a). Notre travail s’est donc concentré sur l’étude de l’impact de l’exercice sur la voie de signalisation PGC-1a/BDNF dans la prévention de la perte de masse musculaire et l’EH chez le rat cirrhotique. Matériel et méthode : La cirrhose et l’EH ont été induites chez le rat 6 semaines après la ligature des voies biliaires (BDL). Quatre groupes expérimentaux ont été constitués : 1) Contrôles; 2) BDL; 3) Contrôles + Exercice 4) BDL+ Exercice. Les rats faisant partie du 3e et du 4e groupe sont soumis à un exercice de type aérobique. L’expression génique et protéique musculaire de PGC-1a et BDNF a été évaluée par immunobuvardage Western. Résultats et discussion :L’exercice augmente l’expression de BDNF mature chez les rats sains, ce qui prévient la fonte musculaire typique de la maladie hépatique et le développement de l’EH. Le rôle du PGC-1a reste à clarifier. Conclusion :Une meilleure compréhension de la voie PGC-1a-BDNF pourrait permettre de cibler le muscle comme thérapie effectrice dans le but d’améliorer le pronostic ainsi que la qualité de vie des patients cirrhotiques. Sincères remerciements à PREMIER-FPC-Département de nutrition et à la Fondation Canadienne du foie

Introduction :L'encéphalopathie hépatique (EH) est une complication neuropsychiatrique majeure de la maladie du foie chronique, telle que la cirrhose du foie. L’une de ses formes est l’EH épisodique dont les symptômes surgissent épisodiquement. Notre hypothèse était que les épisodes d’EH aggraveraient les dommages neurologiques de l’EH et accentueraient ainsi les troubles neurologiques. Toutefois, il n’existe aucun modèle animal d’EH épisodique à ce jour. Nous avions pour but de caractériser un modèle d’EH épisodique due à la cirrhose et d’évaluer l’impact de multiples épisodes sur le dysfonctionnement neurologique. Matériel et méthodes :Une cirrhose hépatique a été provoquée par ligatures du conduit biliaire (BDL) et a été combinée à des injections d’acétate d’ammonium afin d’induire l’EH épisodique dans le rat. La coordination motrice et l’apprentissage moteur ont été évalués avec le test RotaRod et la locomotion avec l’analyse de l’activité nocturne. Résultats et discussion :les déficits de coordination et de locomotion détectés chez les rats BDL ne se sont pas aggravés après des épisodes d’EH. Cependant, les rats cirrhotiques ayant eu des épisodes d’EH présentaient des déficits de coordination motrice après un épisode, alors que les rats cirrhotiques sans épisode ne présentaient pas de déficit de coordination. Un effet synergique de la cirrhose et des épisodes d’EH pourrait causer ces déficits de coordination motrice déjà après un seul épisode. Conclusion :Ce nouveau modèle de l’EH épisodique permettra d’explorer son mécanisme pathologique et d’y tester des traitements.Organisme subventionnaire : PREMIER-Département de médecine

Introduction : Le Syndrome de Leigh version canadienne française (LSFC) est une maladie rare dont l’incidence est élevée dans la région du Saguenay-Lac-Saint-Jean. Il est causé par une mutation du gène « leucine-rich pentatricopeptide repeat motif containing protein » (LRPPRC), entrainant une déficience tissu-spécifique en cytochrome c oxydase de la chaîne respiratoire mitochondriale. L’activité de l’enzyme est réduite jusqu’à 80% dans le foie et le cerveau. Les atteintes hépatiques semblent avoir des répercussions au niveau cérébral; le phénotype consiste en un retard de développement, de l’hypotonie et un dimorphisme facial. Les enfants atteints sont susceptibles de souffrir d’épisodes aiguës d’acidose métabolique (crises) menant à la mort de 80% d’entre eux avant l’âge de 4 ans. Ces crises sont souvent déclenchées par plusieurs changements, incluant une infection ou un apport nutritionnel riche en matières grasses et sucres. Aucune avenue thérapeutique n’existe. Plusieurs recherches portent sur les atteintes hépatiques de la maladie, mais aucune investigation ne s’est penchée sur la caractérisation cérébrale de la microglie. Matériel et méthodes :L’hypothèse est qu’une activation de la microglie, cellules immunitaires du cerveau, est présente dans un modèle expérimental de souris ayant la mutation du gène LRPPRC au niveau hépatique et l’objectif est de caractériser cette activation. L’expression de marqueurs de cellules microgliales est mesurée par immunobuvardage Western, avec l’utilisation d’anticorps primaires (CD11b, OX-42 et Iba-1) spécifiques aux protéines d’intérêt. Résultats et discussion :Aucun anticorps n’a démontré des résultats valides et plusieurs sources d’erreur peuvent expliquer ces résultats. Conclusion :Ce projet de recherche a tenté de caractériser pour la première fois l’activation de la microglie dans un modèle expérimental de la maladie. Considérant les résultats obtenus, il est nécessaire de reproduire cette étude.

Background: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (CLD; cirrhosis) and may increase the risk of developing other complications including hepatic encephalopathy (HE). Malnutrition in cirrhosis may also affect patient’s functional status and health-related quality of life (HRQOL). Management strategies focussing on nutritional status in relation to complications of cirrhosis are an unmet clinical need. We hypothesize that sub-optimal nutritional status in cirrhotic patients increases the risk of developing HE and decreases HRQOL. Purpose: The primary purpose is to compare the nutritional status of adult patients with cirrhosis to non-cirrhotic patients. The secondary purposes is to ascertain hepatic encephalopathy (current and previous history) and quality of life among this population. Method: Hospitalized and outpatients (CHUM’s Liver Unit, Montreal, Canada) with cirrhosis as well as non-cirrhotic (NC) patients were assessed for 1) Nutritional status (Subjective Global Assessment (SGA)); 2) HE (presence or history); 3) HRQOL (Short-Form-36 (SF-36) questionnaire). Results: 50 cirrhotic patients (72% men) of various etiologies, Child-Pugh (15A, 7B, 18C, 10 unknown), mean age 56±12 as well as 18 NC patients (33% men, mean age 42±15) were included. SGA analysis revealed that 34% of cirrhotic patients were malnourished whereas 12% of cirrhotic patients were diagnosed with HE at time of recruitment and 37% had a history of HE. Among malnourished CLD patients, 18% were diagnosed with HE. CLD malnourished patients showed a decreased HRQOL compared to well-nourished CLD patients (p<0,01). Moreover, HE had an impact on HRQOL as cirrhotic patients with a history of HE episode(s) showed decreased physical functioning (p=0,024) and role limitations due to physical health (p=0,002). Interestingly, when compared to NC patients, CLD patients displayed a lower score in physical functioning (p<0,0001) and general health (p=0,027). Conclusion: Our data suggest that poor nutritional status does negatively influence HRQOL in cirrhotic patients but is not associated with HE. However, history of HE episode(s) does impact on HRQOL among this population. Therefore, identifying malnourished patients is of great importance and interventions for treating malnutrition remains an unmet clinical need.

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. AIM: Development of an animal model of cirrhosis and obesity to investigate the synergistic effect of obesity and CLD on the development of neurological impairment and HE. M&M: Animal model of CLD and HE: 6-week bile-duct ligation (BDL) rats, as well as Sham-operated controls, were used. Inducing obesity: High-fat diet (HFD) was given for 3 weeks before BDL or Sham surgery. Groups: 1. Obese-BDL rats received HFD for 3 weeks pre-BDL and regular diet (RD) for 6 weeks post-BDL; 2. Lean-BDL rats received RD pre- and post-BDL; 3. Lean-Sham rats received RD pre- and post-Sham surgery. Behaviour: Recognition memory, motor coordination and muscular strength were assessed before surgery, as well as 3 and 6 weeks post-surgery using the novel object recognition, rotarod and grip strength tests, respectively. Body-composition (echoMRI): Fat vs. lean mass and free water (ascites) were also monitored. RESULTS: Before the surgery, body weight (BW) and fat mass of rats on HFD (Obese-BDL) were increased in comparison to rats on RD (Lean-BDL and Lean-Sham). 3 weeks after surgery, BW, fat mass, lean mass and free water were increased in Obese-BDL rats vs. Lean-BDL rats. Long-term memory was reduced in Obese-BDL, but not in Lean-BDL, vs. Lean-Sham rats. 6 weeks after surgery, similar to Lean-BDL rats, Obese-BDL rats lost BW, fat and Lean mass, while free water increased vs. Lean-Sham rats. Motor coordination, forelimb strength and long-term memory were impaired in Obese-BDL rats in comparison to Lean-BDL or Lean-Sham rats, whereas hind-limb strength and short-term memory were impaired in both Obese- and Lean-BDL rats, compared to Lean-Sham rats. CONCLUSION: HFD induces obesity features in healthy non-cirrhotic rats. Such effects are maintained in cirrhotic-BDL rats. Obesity also accelerates the accumulation of free water in cirrhotic-BDL rats. Interestingly, some neurological impairments are detected in Obese-BDL but not in Lean-BDL rats (long-term memory), while others are exacerbated (motor coordination, forelimb strength). This new animal model of CLD and obesity suggests a synergistic effect, which accelerates and worsens the disease-associated abnormalities observed in CLD and HE. Thus, obesity-induced cirrhosis in patients may result in more complex neurological manifestations, suggesting more susceptibility to poor neurological performance.

The liver plays a major role in regulating ammonia levels in the blood . Therefore, in liver disease, the loss of hepatic function leads to hyperammonemia and consequently hepatic encephalopathy (HE) . Ammonia-lowering strategies remain the mainstay therapeutic strategy for HE . Ammonia, both as an ion (NH4+) and gas (NH3), easily crosses all plasma membranes, including the blood brain barrier (BBB); the interface between the blood and the brain . Glutamine synthetase (GS), an enzyme which in the process of amidating glutamate to glutamine removes ammonia, plays an important compensatory role during liver disease . GS is expressed in liver, muscle and brain (primarily in astrocytes) but has never been thoroughly explored in the BBB . Methods: Using brain primary microvascular endothelial cells (ECs) and isolated cerebral microvessels (CMV) from the frontal cortex of naïve rats, the presence of GS was assessed using rtPCR, western blot (brain used as positive control), immunohistochemistry (co-localized with endothelial cell marker caveolin-1) . GS activity was also assessed . In addition, to understand the effect of liver disease on GS, ECs were exposed to plasma from bile-duct ligated (BDL) rats (model of chronic liver disease) and sham-operated controls, as well as ammonia chloride (1mM) and oxidative stress (10μM of hydrogen peroxide) . Results: Immunohistochemically, GS was detected in ECs and in vessels of brain from naïve rats . Furthermore, ECs expressed GS mRNA, protein and activity . However, expression of GS was lower compared to brain lysate control samples (p<0 .05) . GS expression in CMV showed similar results to brain but GS activity was less (p<0 .05) . When cells were submitted to ammonia, an increase in GS activity was demonstrated (p<0 .05) . However, when exposed to plasma from BDL rats or oxidative stress, GS activity was significantly reduced when compared to controls (p<0 .01) . Conclusion: These results demonstrate for the first time that GS is present in ECs in both in vivo and in vitro . Interestingly, ammonia stimulates GS in endothelial cells, whereas oxidative stress inhibits GS activity . Furthermore, GS activity is decreased in the presence of plasma from cirrhotic rats, possibly due to the presence of systemic oxidative stress in BDL rats. We speculate that a downregulation of GS allows for a faster and easier entry of ammonia into the brain and therefore may increase the risk of HE . We anticipate that upregulating GS in ECs of the BBB could become a new therapeutic target for HE.

Acetaminophen (APAP)-induced acute liver failure (ALF) is associated with significant mortality due to intracranial hypertension (ICH), a result of cerebral edema (CE) and astrocyte swelling. Brain-type fatty acid-binding protein (FABP7) is a small (15 kDa) cytoplasmic protein abundantly expressed in astrocytes. The aim of this study was to determine whether serum FABP7 levels early (day 1) or late (days 3-5) level were associated with 21-day mortality and/or the presence of ICH/CE in APAP-ALF patients. Serum samples from 198 APAP-ALF patients (nested case-control study with 99 survivors and 99 non-survivors) were analyzed by ELISA methods and assessed with clinical data from the US Acute Liver Failure Study Group (ALFSG) Registry (1998-2014). APAP-ALF survivors had significantly lower serum FABP7 levels on admission (147.9 vs. 316.5 ng/ml, p = 0.0002) and late (87.3 vs. 286.2 ng/ml, p < 0.0001) compared with non-survivors. However, a significant association between 21-day mortality and increased serum FABP7 early [log FABP7 odds ratio (OR) 1.16, p = 0.32] and late (log FABP7 OR 1.34, p = 0.21) was not detected after adjusting for significant covariates (MELD, vasopressor use). Areas under the receiver-operating curve for early and late multivariable models were 0.760 and 0.892, respectively. In a second analysis, patients were grouped based on the presence (n = 46) or absence (n = 104) of ICH/CE. A significant difference in FABP7 levels between patients with or without ICH/CE at early (259.7 vs. 228.2 ng/ml, p = 0.61) and late (223.8 vs. 192.0 ng/ml, p = 0.19) time points was not identified. Serum FABP7 levels were significantly elevated at early and late time points in APAP-ALF non-survivors compared to survivors. However, significant differences in FABP7 levels by 21-day mortality were not ascertained after adjusting for significant covariates (reflecting severity of illness). Our study suggests that FABP7 may not discriminate between patients with or without intracranial complications.

Introduction: Hepatic encephalopathy (HE) is a neuropsychiatric disorder, a major complication of chronic liver disease (CLD). Hyperammonemia is central in the pathogenesis of HE as ammonia easily crosses the blood brain barrier (BBB) causing toxicity. Glutamine synthetase (GS), an enzyme which removes ammonia, plays an important compensatory role during CLD and is known to be expressed in muscle and brain. However, its expression in endothelial cells (EC) of the BBB has never been explored. Methods: GS protein and activity was assessed in 1) rat brain microvascular EC (+/- ammonia exposure and conditioned media from rats with CLD) and 2) isolated cerebral microvessels (CMV) from naïve rats. Results: GS was co-localized with EC in brain of naïve rats. GS protein and activity was detected in CMV, with less activity compared to brain (p<0.05). In vitro, EC expressed GS protein with activity, but lower compared to brain (p<0.05). EC exposed to ammonia resulted in increased GS activity (p<0.05). However, ECs exposed to plasma from CLD rats had lower GS activity and protein expression compared to controls (p<0.05). Conclusion: We demonstrate for the first time the presence of GS in EC. Stimulated by ammonia, GS is however reduced with conditioned plasma from hyperammonemic CLD rats. This suggests other factors such as oxidative stress (present in CLD) could lead to GS inhibition. We speculate a downregulation of GS in the BBB during CLD leads to rapid entry of ammonia into the brain and HE. Therefore upregulating GS in the BBB could become a new therapeutic target for HE.

BACKGROUND: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. AIM: To develop and characterize an animal model of cirrhosis and obesity to investigate the synergistic effect of obesity and CLD on the development of neurological impairment and HE. M&M: Animal model of CLD and HE: The 6-week bile-duct ligation (BDL) rats and sham-operated controls, were used. Obesity: To induce obesity, high-fat diet (HFD) was given for 3 weeks before BDL. Experimental groups: 1. Obese-BDL rats received HFD for 3 weeks pre-BDL and normal diet (ND) for 6 weeks post-BDL; 2. Lean-BDL rats received ND pre- and post-BDL; 3. Lean-Sham rats received ND pre- and post-sham surgery. Behaviour: Motor coordination, muscular strength, and recognition memory were assessed before surgery, as well as 3 and 6 weeks post-BDL or sham surgery using the RotaRod, grip-strength and object recognition tests, respectively. Body-composition (echoMRI): Fat vs lean mass, as well as free water were also monitored. RESULTS: Before the surgery, body weight and fat mass of rats on HFD (Obese-BDL) were increased in comparison to rats on ND (Lean-BDL and Lean-Sham). Three weeks after surgery, body-weight, fat mass, lean mass and free water were increased in Obese-BDL rats vs Lean-BDL rats. Long-term memory was reduced in Obese-BDL, but not in Lean-BDL, vs Lean-Sham rats. Six weeks after surgery, similar to Lean-BDL rats, Obese-BDL rats lost body weight, fat and lean mass, and increased free water vs Lean-Sham rats. Motor coordination, forelimb strength and long-term memory were impaired in Obese-BDL rats in comparison to Lean-BDL or Lean-Sham rats, whereas hind-limb strength and short-term memory were impaired in both Obese- and Lean-BDL rats vs Lean-Sham rats. SUMMARY: HFD induces obesity features in healthy non-cirrhotic rats, and such effects are maintained in cirrhotic-BDL rats. Obesity also worsens and accelerates the accumulation of free water in cirrhotic-BDL rats. Interestingly, some neurological impairments are detected in Obese-BDL but not in Lean-BDL rats, such as long-term memory, motor coordination and forelimb strength deficits. This new animal model of CLD and obesity suggests a synergic effect, which accelerates and worsens the disease-associated abnormalities observed in CLD and HE. CONCLUSION: Obesity-induced cirrhosis in patients may result in more complex neurological manifestations, suggesting that these patients might be more susceptible to neuronal dysfunction and poor neurological performance. Therefore, this model of CLD and obesity will provide important clues to the underlying mechanisms of HE associated with obesity-induced cirrhosis and provide new insights into novel therapeutic strategies.

Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (cirrhosis; CLD). Malnutrition may increase the risk of developing other complications including hepatic encephalopathy (HE). Malnutrition in cirrhosis may also affect patient’s functional status and health-related quality of life (HRQOL). Management strategies focussing on nutritional status in relation to complications of cirrhosis are an unmet clinical need. We hypothesize sub-optimal nutritional status in cirrhotic patients increases the risk of developing HE and decreases HRQOL. Hospitalized and outpatients (CHUM’s Liver Unit in Montreal, Canada) with liver cirrhosis of different etiologies and healthy controls were assessed for 1) Nutritional status (Subjective Global Assessment (SGA)); 2) HE (Clinical HE Staging Scale (CHESS)); 3) HRQOL (Short-Form-36 (SF-36) questionnaire). This on-going prospective study included 33 cirrhotic patients (58% men) of various etiologies (% : 30 alcohol, 33 virus, 27 NASH and 33 others), Child-Pugh (13A, 9B, 5C and 6N/A), mean age 55,7±12,9 as well as 13 healthy controls (46% men, mean age 49,4±14,9). SGA analysis revealed that 27% of cirrhotic patients were malnourished. Furthermore, cirrhotic malnourished patients show decreased HRQOL compared to well-nourished cirrhotic patients (p<0.01). Cirrhotic patients, when compared to controls, displayed a lower score in physical functioning (p=0.03) and general health (p=0.03). CHESS analysis revealed none of the cirrhotic patients had HE while 21% of them had an HE diagnosis in medical chart, suggesting CHESS would not be sensible enough to screen HE. Our preliminary results suggest that nutritional status does influence particular domains of HRQOL in cirrhotic patients irrespective of their etiology. Further patients are required to statistically confirm the impact of nutritional status on HE and HRQOL in cirrhotic patients. Identifying factors associated with nutritional status, HRQOL and HE in cirrhotic patients may help improve patient care and guide future research.

Introduction: Hepatic encephalopathy (HE) is a neuropsyc hiatric disorder, a major complication of chronic liver disease (CLD). Hyperammonemia is central in the pathogenesis of HE as ammonia easily crosses the blood brain barrier (BBB) causing toxicity. Glutamine synthetase (GS), an enzyme which removes ammonia, plays an important compensatory role during CLD and is known to be expressed in muscle and brain. However, its expression in endothelial cells (EC) of the BBB has never been explored. Methods: GS protein and activity was assessed in 1) rat brain microvascular EC (+/- ammonia exposure and plasma from rats with CLD) and 2) isolated cerebral microvessels (C MV) from naïve rats. Results: GS was co-localized with EC in brain of naïve rats. GS protein and activity was detected in CMV, with less activity compared to brain (p<0.05). In vitro, GS protein and activity was detected in EC, but with lower levels compared to brain (p<0.05). EC exposed to ammonia resulted in increased GS activity (p<0.05). However, ECs exposed to plasma fr om CLD rats resulted in lower GS activity and protein expression compared to controls (p<0.05). Conclusion: We demonstrate for the first time the presence of GS in EC in both in vitro and in vivo. Stimulated by ammonia, GS is however reduced following exposur e to plasma from hyperammonemic CLD rats. This suggests other systemic factors such as oxidative stress (present in CLD; Bosoi et al., Free Radic Biol Med, 2012) could negative affect GS activity. We speculate a downregulation of GS in the BBB during CLD leads to rapid entry of ammonia into t he brain and the development of HE. H ence, upregulating GS in the BBB could become a new therapeutic target for HE.

Introduction : L'encéphalopathie hépatique (EH) est une complication neuropsychiatrique majeure de la maladie du foie chronique, telle que la cirrhose du foie. L’une de ses formes est l’EH épisodique dont les symptômes surgissent épisodiquement. Notre hypothèse était que les épisodes d’EH aggraveraient les dommages neurologiques de l’EH etaccentueraient ainsi les troubles neurologiques. Toutefois, il n’existe aucun modèle animal d’EH épisodique à ce jour. Nous avions pour but de caractériser un modèle d’EH épisodique due à la cirrhose et d’évaluer l’impact de multiples épisodes sur le disfonctionnement neurologique.Matériel et méthodes : Une cirrhose hépatique a été provoquée par la chirurgie du bile duct ligation (BDL) et a été combinée à des injections d’acétate d’ammonium afin d’induire l’EH épisodique dans le rat. Les niveaux d’ammoniaque ont été mesurés. Les mémoires à court et long terme ont été évaluées avec le Novel Object Recognition test ; l’anxiétéavec le Elevated Plus Maze test ; et la coordination motrice avec le RotaRod test. Résultats : Les déficits de mémoire à court terme et de coordination motrice chez les rats BDL avec épisodes d’EH n’étaient pas altérés comparés aux rats BDL sans épisodes. Toutefois, leur mémoire à long terme a été réduite, et leurs niveaux d’anxiété et d’ammoniaque plasmique ont été augmentés. Discussion et conclusion : Un effet synergique de la cirrhose, des épisodes d’EH et des niveaux élevés d’ammoniaquepourraient causer ces altérations. Ce nouveau modèle de l’EH épisodique permettra d’explorer son mécanisme pathologique et d’y tester des traitements. Projet subventionné par la COPSE et la CLF.

Introduction: La malnutrition est un facteur pronostic important influençant l’issue clinique des patients souffrant de maladie hépatique chronique (MHC). La malnutrition accroît le risque de développer d'autres complications, incluant l'encéphalopathie hépatique (EH) et peut également affecter la qualité de vie (QV). Objectif: Comparer l’état nutritionnel des patients MHC aux sujets non-cirrhotiques (NC) et son impact sur l’EH et la QV. Méthodes: 33 patients MHC, étiologies et sévérité de maladie (Child-Pugh Score) diverses et 13 sujets NC ont été évalués pour: A) État nutritionnel (ESG); B) EH (CHESS); C) QV (SF-36). Résultats: Cette étude prospective en cours inclut 33 patients MHC (58% hommes) d’étiologies variées (%: 30 Alcool, 33 Virus, 27 NASH et 33 autres), Child-Pugh (13A, 9B, 5C et 6N/D), âgés de 55,7±12,9 ans et 13 sujets NC (46% hommes, 49,4±14,9 ans). L’ESG révèle que 27% des patients MHC souffrent de malnutrition et présentent un score moindre de fonctionnement physique (p = 0,03) et de santé générale (p=0,03), comparativement aux sujets NC. Aussi, les patients MHC malnutris présentent une diminution de la QV par rapport aux sujets MHC bien nourris (p<0,01). L'analyse de CHESS a révélé qu'aucun des patients MHC n'avaient d'EH alors que 21% d'entre eux avaient un diagnostic médical positif, ce qui suggère que le CHESS ne serait pas assez sensible pour dépister l'EH. Discussion : Ces résultats suggèrent que l'état nutritionnel influe sur la QV des sujets MHC sans égard à l’étiologie. D'autres patients sont nécessaires pour confirmer l'impact de l'état nutritionnel chez les patients MHC et ce, afin d’améliorer les soins et guider les recherches futures.

Problématique : La malnutrition est un facteur pronostic important influençant l’issue clinique des patients souffrant de maladie hépatique chronique (MHC). La malnutrition accroît le risque de développer d'autres complications, incluant l'encéphalopathie hépatique (EH) et peut également affecter la qualité de vie (QV). Les stratégies thérapeutiques axées sur l'état nutritionnel en relation avec les complications de la cirrhose représentent un besoin clinique urgent. Objectif : Comparer l’état nutritionnel des patients MHC aux contrôles sains et son impact sur l’EH et la QV. Méthodologie : 33 patients MHC d’étiologies et de sévérité de maladie (Child-Pugh Score) diverses et 13 contrôles sains ont été évalués pour : A) État nutritionnel (ESG); B) EH (CHESS); C) QV (SF-36). Résultats : Cette étude prospective en cours inclut 33 patients MHC (58% hommes) d’étiologies variées (% : 30 Alcool, 33 Virus, 27 NASH et 33 autres), Child-Pugh (13A, 9B, 5C et 6N/D), âgés de 55,7±12,9 ans et 13 témoins sains (46% hommes, 49,4±14,9 ans). L’ESG révèle que 27% des sujets MHC souffrent de malnutrition et présentent un score moindre de fonctionnement physique (p = 0,03) et de santé générale (p=0,03), comparativement aux contrôles sains. Aussi, les patients MHC malnutris présentent une diminution de la QV par rapport aux patients MHC bien nourris (p<0,01). Discussion : Les résultats préliminaires suggèrent que l'état nutritionnel influe sur la QV des sujets MHC sans égard à l’étiologie. D'autres patients sont nécessaires pour confirmer l'impact de l'état nutritionnel chez les patients MHC, afin d’améliorer les soins et guider les recherches futures.

Problématique : La malnutrition est un facteur pronostic important influençant l’issue clinique des patients souffrant de maladie hépatique chronique (MHC). La malnutrition accroît le risque de développer d'autres complications, incluant l'encéphalopathie hépatique (EH) et peut également affecter la qualité de vie (QV). Les stratégies thérapeutiques axées sur l'état nutritionnel en relation avec les complications de la cirrhose représentent un besoin clinique urgent. Objectif : Comparer l’état nutritionnel des patients MHC aux contrôles sains et son impact sur l’EH et la QV. Méthodologie : 33 patients MHC d’étiologies et de sévérité de maladie (Child-Pugh Score) diverses et 13 contrôles sains ont été évalués pour : A) État nutritionnel (ESG); B) EH (CHESS); C) QV (SF-36). Résultats : Cette étude prospective en cours inclut 33 patients MHC (58% hommes) d’étiologies variées (% : 30 Alcool, 33 Virus, 27 NASH et 33 autres), Child-Pugh (13A, 9B, 5C et 6N/D), âgés de 55,7±12,9 ans et 13 témoins sains (46% hommes, 49,4±14,9 ans). L’ESG révèle que 27% des sujets MHC souffrent de malnutrition et présentent un score moindre de fonctionnement physique (p = 0,03) et de santé générale (p=0,03), comparativement aux contrôles sains. Aussi, les patients MHC malnutris présentent une diminution de la QV par rapport aux patients MHC bien nourris (p<0,01). Discussion : Les résultats préliminaires suggèrent que l'état nutritionnel influe sur la QV des sujets MHC sans égard à l’étiologie. D'autres patients sont nécessaires pour confirmer l'impact de l'état nutritionnel chez les patients MHC, afin d’améliorer les soins et guider les recherches futures.

BACKGROUND: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. AIM: To develop and characterize an animal model of cirrhosis and obesity to investigate the impact of obesity on the development of neurological impairment in cirrhotic rats. M&M: Obesity: To induce obesity, high-fat diet (HFD) was given for 3 weeks before surgical intervention (bile-duct ligation (BDL) or Sham). Experimental groups: 1. Obese-BDL: rats received HFD for 3 weeks pre-BDL and normal diet (ND) for 6 weeks post-BDL; 2. Lean-BDL: rats received ND pre- and post-BDL; 3. Lean-Sham: rats received ND pre- and post-sham surgery. HE parameters: Motor coordination, muscular strength, and recognition memory were assessed pre-pre-, 3 and 6 weeks post-surgical intervention using RotaRod, grip- strength and object recognition test respectively. Body-composition (echoMRI): Fat, lean mass and free water were monitored. RESULTS: Three weeks HFD lead to an increase in fat mass in comparison to rats on ND (p<0.01). Three weeks after surgery, fat, and lean mass and free water were increased in Obese-BDL vs Lean-BDL rats (p<0.05). Long-term memory was reduced in Obese-BDL, but not in Lean-BDL, vs Lean-Sham rats (p<0.05). Six weeks after surgery, similar to Lean-BDL rats, Obese-BDL rats lost fat and lean mass, and increased free water vs Lean-Sham rats (p<0.5). Motor coordination, forelimb strength and long-term memory were impaired in Obese-BDL rats in comparison to Lean-BDL and Lean-Sham rats (p<0.01), whereas hind-limb strength and short-term memory were impaired in both Obese- and Lean-BDL rats when compared to Lean-Sham rats (p<0.01). CONCLUSION: Obesity exacerbates and accelerates the accumulation of free water and motor coordination deficits in cirrhotic-BDL rats. Interestingly, long-term memory and forelimb strength deficits were impaired in Obese-BDL but not in Lean-BDL rats. This novel animal model of CLD and obesity suggests obesity accelerates CLD-induced neurological impairment. Therefore, this model of CLD and obesity will provide important clues to the underlying mechanisms of HE associated with obesity-induced cirrhosis and provide new insights into novel therapeutic strategies.

Background: The liver plays a major role in regulating ammonia levels in the blood. Therefore, impaired hepatic function leads to hyperammonemia and consequently hepatic encephalopathy (HE). Ammonia easily crosses the blood brain barrier (BBB); the interface between the blood and the brain. Glutamine synthetase (GS), an enzyme which during the process of amidating glutamate to glutamine removes ammonia, plays an important compensatory role during liver disease. GS is expressed in muscle and brain but has never been thoroughly explored in the endothelial cells of the BBB. Methods: Using primary rat brain microvascular endothelial cells (ECs), the presence of GS was assessed using rtPCR, western blot, immunohistochemistry and activity assay. Furthermore, we isolated cerebral microvessels (CMV) from the frontal cortex of naïve rats and measured GS activity and protein expression (brain lysate was used as positive control). GS was also evaluated by immunohistochemistry (co-localized with caveolin-1 (marker for ECs). In addition, GS activity was assessed in ECs exposed to 1mM of ammonium chloride for 48h. Finally, GS activity and protein expression were evaluated in ECs exposed to plasma from 6-week bile-duct ligated (BDL) rats or sham-operated controls for 72h. Results: ECs expressed mRNA, protein and activity of GS. However, EC`s expression (normalized to g/protein) of GS was lower compared to brain lysate control samples (p<0.05). The quantity of GS protein in CMV was similar to that found in brain but the activity of GS was significantly less in CMV (p<0.05). Using immunohistochemistry, GS was detected in ECs and in CMV from naïve rats. When ECs were exposed to ammonia (1mM), an increase in GS activity was demonstrated (p<0.05). However, when exposed to conditioned medium from BDL rats, GS activity and protein expression were decreased when compared to sham-operated controls (p<0.05). Discussion: These results demonstrate for the first time that GS is present in ECs. Interestingly, ammonia stimulates GS activity in ECs, but is reduced following treatment with plasma from BDL rats. This suggests other factors such as oxidative stress and inflammation (present in BDL rats), could inhibit GS activity. We speculate that a downregulation of GS in the BBB allows for a faster entry of ammonia into the brain and therefore may play a significant role in the onset of HE. We anticipate upregulating GS in ECs of the BBB could become a new therapeutic target for HE

Muscle mass loss and hepatic encephalopathy (complex neuropsychiatric disorder) are serious complications of chronic liver disease (cirrhosis) which impact negatively on clinical outcome and quality of life and increase mortality. Liver disease leads to hyperammonemia and ammonia toxicity is believed to play a major role in the pathogenesis of hepatic encephalopathy. However, the effects of ammonia are not brain-specific and therefore may also affect other organs and tissues including muscle. The precise pathophysiological mechanisms underlying muscle wasting in chronic liver disease remains to be elucidated. In the present study, we characterized body composition as well as muscle protein synthesis in cirrhotic rats with hepatic encephalopathy using the 6-week bile duct ligation (BDL) model which recapitulates the main features of cirrhosis. Compared to sham-operated control animals, BDL rats display significant decreased gain in body weight, altered body composition, decreased gastrocnemius muscle mass and circumference as well as altered muscle morphology. Muscle protein synthesis was also significantly reduced in BDL rats compared to control animals. These findings demonstrate that the 6-week BDL experimental rat is a relevant model to study liver disease-induced muscle mass loss.

Background: Acetaminophen (APAP) - induced acute liver failure (ALF) is associated with significant mortality. To date, traditional prognostic scores lack discrimination in identifying patients with APAP-ALF who will die without liver transplant (LT), and those who will survive with medical management alone. Failure to identify those in need of LT results in a potentially preventable death while wrongly classifying prospective survivors as in need of LT subjects the patient to unnecessary LT. Liver-type fatty acid binding protein (FABP1) is a small (15 kDa) cytoplasmic protein abundantly expressed in hepatocytes. The prognostic value of serum FABP1 levels in APAP-ALF patients has not been reported. Aim: To determine whether serial samples (early; day 1 or late; day 3-5) of serum FABP1 levels are associated with 21-day mortality in the absence of LT. Methods: Nested case control study 198 APAP-ALF patients (99 survivors, 99 non-survivors) from the US Acute Liver Failure Study Group (ALFSG) Registry. Patient samples were analyzed for FABP1 using solid-phase enzyme-linked immunosorbent assay (ELISA) and assessed with clinical data. In addition, 51 healthy controls (University of Alberta) were included. Results: APAP-ALF survivors had significantly lower serum FABP1 levels on admission (238.6 vs. 690.8 ng/ml, P<0.0001) and late (148.4 vs. 612.3 ng/ml, P<0.0001) compared with non-survivors (Figure 1). Using multivariable logistic regression, increased serum FABP1 early (Log FABP1 Odds Ratio (OR) 1.31, P=0.03) and late (Log L-FABP OR 1.50, P=0.005) were associated with significantly increased 21-day mortality after adjusting for significant covariates (MELD, vasopressor use). Area under the receiver operating curve (AUROC) for early and late multivariable models were 0.778 and 0.907 respectively. The addition of FABP1 (Table 1) significantly improved the AUROC of the King’s College Criteria (KCC) (Early: 0.552 alone, 0.711 with L-FABP; Late: 0.604 alone, 0.797 with FABP1, respectively) as well as the ALFSG prognostic index (Early: 0.686 alone, 0.766 with FABP1; Late: 0.711 alone, 0.815 with FABP1, respectively). Summary: Serum levels of FABP1 in APAP-ALF patients were significantly associated with 21-day mortality measured at early and late time points after adjusting for significant covariates. FABP1 improved performance (AUROC) when combined with existing prognostic scores at serial time points. Conclusions: In patients with APAP-ALF, FABP1 showed good potential to discriminate survivors from non- survivors at multiple time-points and significantly improved models currently used in clinical practice. Validation of FABP1 as a clinical prediction tool in APAP-ALF merits further investigation. The study was sponsored by NIH grant U-01 58369 (from NIDDK) and a grant from the University of Alberta Hospital Foundation (UHF).

Background and Aims: Chronic liver disease (CLD) induces numerous complications including muscle mass loss and hepatic encephalopathy (HE) which negatively impact clinical outcomes. Hyperammonemia is considered the central component in the pathogenesis of HE, however recent studies have suggested ammonia to be toxic to other organs/tissues aside the brain, such as the muscle. The aim of this study was to investigate the effect of lowering ammonia on muscle mass in cirrhotic rats treated with an oral formulation of ornithine phenylacetate (OP; OCR-002). Methods: Six-week bile-duct ligated (BDL) and sham rats were used. OP was administered orally by gavage (1g/kg) daily for 5 weeks starting 1 week after surgery. Locomotor activity (day/night) was assessed in infrared beam cages for 24 h. Body weight, fat and lean mass (EchoMRI) were measured. Stable isotope tracers were injected (ip) in order to assess fractional protein synthesis rate (FSR). Blood ammonia and cerebral edema was also evaluaeted. Results: BDL rats demonstrated a 4-fold increase in blood ammonia vs sham-operated controls. This increase was reduced by 40% in OP-treated BDL rats. BDL rats gained less body weight compared to sham-operated controls (body weight of 360.2g ± 13.6 vs 476.8g ± 10.38 p<0.001) which was accompanied with a lower gain of lean mass and a lower muscle FSR. OP-treated BDL rats showed a significant increase in body weight (p<0.001 vs BDL) with a significant higher lean mass (303.1g ± 10.7 in BDL+OP vs 264.4g ± 10.5 in BDL p<0.01). Fat mass remained unchanged between the treated and untreated BDL groups. OP treatment normalized brain water content in BDL rats. In contrast, OP-treatment reduced muscle FSR in SHAM animals, but not in BDL rats. Locomotor activity in BDL rats was reduced compared with sham-operated controls but no significant change was found between BDL+OP and SHAM+OP. Conclusions: This is the first study demonstrating the efficient ammonia-lowering effect of an oral formulation of OP. Long-term treatment with OP is a safe, effective, non-antibiotic alternative demonstrating a significant ammonia-lowering effect, as well as a protective effect on the development of brain edema and muscle mass loss in rats with CLD. Whether the beneficial effect of OP on muscle mass loss is a result of lowering blood ammonia or direct result of OP on muscle metabolism remains to be established.

Background: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (cirrhosis; CLD). Malnutrition may increase the risk of developing other complications including hepatic encephalopathy (HE). Malnutrition in cirrhosis may also affect patient’s functional status and wellbeing or health-related quality of life (HRQOL). Management strategies focussing on nutritional status in relation to complications of cirrhosis are an unmet clinical need. We hypothesize sub-optimal nutritional status in cirrhotic patients increases the risk of developing HE and decreases HRQOL. Methods: 33 patients (outpatients and hospitalized; CHUM’s Liver Unit in Montreal, Canada) with liver cirrhosis of different etiologies and 13 healthy controls were assessed for 1) Nutritional status (Subjective Global Assessment (SGA)); 2) HE (Clinical HE Staging Scale (CHESS)); 3) HRQOL (Short-Form-36 (SF-36) questionnaire). Results: This on-going prospective study included 33 cirrhotic patients (58% men) of various etiologies (30% alcohol, 33 % virus, 27% NASH and 33% others), Child-Pugh A/B/C (13A, 9B, 5C and 6 N/A), mean age 55,7±12,9 as well as 13 healthy controls (46% men, mean age 49,4±14,9). SGA analysis revealed that 27% of cirrhotic patients were malnourished in which 22% of them malnourished showed signs of HE as assessed by CHESS. Cirrhotic patients, when compared to controls, displayed a lower score in physical functioning (p=0.03) and general health (p=0.03), both part of the physical health domain of SF-36. Furthermore, cirrhotic malnourished patients show decreased physical aspects of HRQOL compared to well-nourished cirrhotic patients (p<0.01). Conclusion: Our preliminary results suggest that nutritional status does influence particular domains of HRQOL in cirrhotic patients irrelevant of their etiology. Further patients are required to statistically confirm the impact of nutritional status on HE and HRQOL in cirrhotic patients. Identifying factors associated with nutritional status, HRQOL and HE in cirrhotic patients may help improve patient care and guide future research.

Background/Aims: Skeletal muscle abnormalities, such as sarcopenia and myosteatosis are frequent complications of cirrhosis and are associated with increased morbidity and mortality. Hyperammonemia plays a significant role in the pathogenesis of hepatic encephalopathy (HE). Skeletal muscle have a significant compensatory part in detoxifying ammonia during liver disease since it houses the enzyme glutamine synthetase, an important ammonia-removing pathway during the amination of glutamate to glutamine. Therefore, we aimed to investigate whether reduced quantity and quality of muscle is associated with hyperammonemia, HE and mortality in patients with cirrhosis. Methods: A total of 677 cirrhotic patients were evaluated. Computed tomography (CT) scans were used to analyze the skeletal muscle (transverse CT image at the level of the 3rd. lumbar vertebra (L3) was selected from each scan) and sarcopenia and myosteatosis was evaluated. Overt HE was assessed clinically and ammonia blood levels were performed at the time of the muscularity assessment. Results: Sarcopenia was noted in 292 patients (43%), and 352 patients had myosteatosis (52%). A total of 225 patients (33%) had history of overt HE and 221 (of 267) patients (83%) had hyperammonemia. The prevalence of overt HE was higher in patients with sarcopenia (42% vs. 27%, P<0.001), and myosteatosis (41% vs. 25%, P<0.001). By multivariable regression analysis, sarcopenia and myosteatosis were independently associated with higher risk of overt HE (HR 1.89, P=0.007, HR 1.68, P=0.03) and hyperammonemia (HR 1.71, P=0.006, HR 1.88, P=0.001, respectively). Median survival was worse in patients with overt HE and sarcopenia (18±4 vs. 42±7 months, P=0.01), hyperammonemia and sarcopenia (11±7 vs. 38±16 months, P<0.001), and myosteatosis and hyperammonemia (19±3 vs. 38±20 months, P=0.005) compared to patients without these factors. Conclusions: Cirrhotic patients with sarcopenia and myosteatosis have a higher risk of hyperammonemia and overt HE. Further, skeletal muscle abnormalities present concomitantly with HE and hyperammonemia increase the risk of mortality in these patients.

Therefore, during liver disease, the loss of hepatic function leads to hyperammonemia and consequently increased brain ammonia and hepatic encephalopathy (HE). Reducing ammonia neurotoxicity through systemic ammonia-lowering strategies remains the mainstay therapeutic strategy for HE. Ammonia, both as an ion (NH4+) and gas (NH3), easily crosses all plasma membranes, including the blood brain barrier (BBB); the interface between the blood and the brain. Glutamine synthetase (GS), an enzyme which during the process of amidating glutamate to glutamine removes ammonia, plays an important compensatory role during liver disease. GS is expressed in muscle and brain (astrocytes) but has never been thoroughly explored in the endothelial cells of the BBB. Methods: Using primary rat brain microvascular endothelial cells (ECs), the presence of GS was assessed using rtPCR, western blot, immunohistochemistry and activity assay. Furthermore, we isolated cerebral microvessels (CMV) from the frontal cortex of naïve rats and measured GS activity and protein expression (brain lysate was used as positive control). GS was also evaluated by immunohistochemistry (co-localized with caveolin-1 (marker for ECs). In addition, GS activity was assessed in ECs exposed to 1mM of ammonium chloride for 48h. Finally, GS activity and protein expression were evaluated in ECs submitted to plasma from 6-week bile-duct ligated (BDL) rats or sham-operated controls for 72h. Results: ECs expressed mRNA, protein and activity of GS. However, EC`s expression (normalized to g/protein) of GS was lower compared to brain lysate control samples (p<0.05). GS protein expression in CMV showed similar results to that of brain but GS activity was significantly less in CMV (p<0.05). Using immunohistochemistry, GS was detected in ECs and in CMV from naïve rats. When ECs were exposed to ammonia (1mM), an increase in GS activity was demonstrated (p<0.05). However, when exposed to conditioned medium from BDL rats, GS activity and protein expression were decreased when compared to sham-operated controls (p<0.05). Discussion: These results demonstrate for the first time that GS is present in ECs in both in vivo and in vitro. The lower expression of the enzyme in CMVs compared to that found in the brain, could reason why GS has never been reported in these cells. Interestingly, ammonia stimulates GS activity in ECs, but GS activity is decreased following treatment with plasma from BDL rats. This suggests other factors such as oxidative stress and inflammation, could inhibit GS activity. We speculate that a downregulation of GS in the BBB allows for a faster entry of ammonia into the brain and therefore may play a significant role in the onset of HE. We anticipate upregulating GS in ECs of the BBB could become a new therapeutic target for HE.

Background: Malnutrition is one of the most common complications in the increasing number of patients suffering from chronic liver disease (CLD) and is a leading cause of morbidity and mortality. Traditional tools used to evaluate nutritional status are not reliable in CLD due to limitations related to weight, which may be artificially increased by the presence of ascites, underestimating malnutrition. New strategies to assess nutritional status focusing on early malnutrition detection are an unmet clinical need. The aim of this pilot study is to describe the performance of different measures of nutrition including body mass index (BMI), handgrip strength (HGS), mid-arm muscle circumference (MAMC) in relation to subjective global assessment (SGA). Methods: In this ongoing prospective study, patients with and without CLD are recruited at Centre Hospitalier de l’Université de Montréal (St-Luc Hospital) in Canada. We assess nutritional status via: BMI, HGS as measured with a calibrated dynamometer, MAMC calculated with the mid-arm circumference and the tricipital skinfold and a modified version of the SGA for CLD patients, Spearman correlation coefficient is used to assess correlation between different tools. Results : We recruited 36 and 18 patients with and without CLD and 18 patients, respectively. Conclusions: Our preliminary results indicate that BMI and HGS, but not MAMC tend to decrease according to the nutritional status (no malnutrition, mild or moderate malnutrition) determined by SGA. Further patients are required to statistically identify a reliable tool and be able to evaluate nutritional status in cirrhosis as well as detect malnutrition in its early stage.

BACKGROUND: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. AIM: To develop and characterize an animal model of cirrhosis and obesity to investigate the synergistic effect of obesity and CLD on the development of neurological impairment and HE. M&M: Animal model of CLD and HE: The 6-week bile-duct ligation (BDL) rats, as well as sham-operated controls, were used. Obesity: To induce obesity, high-fat diet (HFD) was given for 3 weeks before BDL. Experimental groups: 1. Obese-BDL rats received HFD for 3 weeks pre-BDL and normal diet (ND) for 6 weeks post-BDL; 2. Lean-BDL rats received ND pre- and post-BDL; 3. Lean-Sham rats received ND pre- and post-sham surgery. Behaviour: Motor coordination, muscular strength, and recognition memory were assessed before surgery, as well as 3 and 6 weeks post-BDL or sham surgery using the RotaRod, grip-strength and object recognition tests, respectively. Body-composition (echoMRI): Fat vs lean mass, as well as free water (ascites, fluid retention), were also monitored. RESULTS: Before the surgery, body weight and fat mass of rats on HFD (Obese-BDL) were increased in comparison to rats on ND (Lean-BDL and Lean-Sham). Three weeks after surgery, body-weight, fat mass, lean mass and free water were increased in Obese-BDL rats vs Lean-BDL rats. Long-term memory was reduced in Obese-BDL, but not in Lean-BDL, vs Lean-Sham rats. Six weeks after surgery, similar to Lean-BDL rats, Obese-BDL rats lost body weight, fat and lean mass, and increased free water vs Lean-Sham rats. Motor coordination, forelimb strength and long-term memory were impaired in Obese-BDL rats in comparison to Lean-BDL or Lean-Sham rats, whereas hind-limb strength and short-term memory were impaired in both Obese- and Lean-BDL rats when compared to Lean-Sham rats. SUMMARY: HFD induces obesity features in healthy non-cirrhotic rats, and such effects are maintained in cirrhotic-BDL rats. Obesity also exacerbates and accelerates the accumulation of free water in cirrhotic-BDL rats. Interestingly, some neurological impairments are detected in Obese-BDL but not in Lean-BDL rats, such as long-term memory, motor coordination and forelimb strength deficits. This new animal model of CLD and obesity suggests a synergic effect, which accelerates and worsens the disease-associated abnormalities observed in CLD and HE. CONCLUSION: Obesity-induced cirrhosis in patients may result in more complex neurological manifestations, suggesting that these patients might be more susceptible to neuronal dysfunction and poor neurological performance. Therefore, this model of CLD and obesity will provide important clues to the underlying mechanisms of HE associated with obesity-induced cirrhosis and provide new insights into novel therapeutic strategies.

Background: Acetaminophen (APAP) - induced Acute Liver Failure (ALF) is associated with significant morbidity and mortality related to cerebral edema (CE) and intracranial hypertension (ICH). Brain type fatty acid binding protein (FABP7) is a small (15 kDa) cytoplasmic protein abundantly expressed in astrocytes where there is active fatty acid metabolism. FABP7 levels have not been previously reported in ALF patients at high risk of CE/ICH. Aims: One: To determine whether serum FABP7 early (day 1) or late (day 3-5) levels are associated with 21-day mortality in APAP-ALF patients in the absence of liver transplant. Two: To determine whether serum FABP7 levels at serial time points are associated with the presence of ICH/CE Methods: Nested case control study 198 APAP-ALF patients (99 survivors, 99 non-survivors) from the US Acute Liver Failure Study Group (ALFSG) registry. Patient samples were analyzed for FABP1 using solidphase enzyme-linked immunosorbent assay (ELISA) and assessed with clinical data. In a second analysis where data were available, patients were stratified based on the presence of ICH/CE (n=46) or absence (n=104) based on death summaries or clinical data (ICP monitor, computed tomography). Multivariable logistic regression was used to determine independent associations with 21-day mortality (n=198) and development of ICH/CE (n=150) Results: APAP-ALF survivors had significantly lower serum FABP7 levels on admission (147.9 vs. 316.5 ng/ml, P=0.0002) and late (87.3 vs. 286.2 ng/ml, P<0.0001) compared with nonsurvivors (Figure 1). However using multivariable logistic regression, a significant association between 21- day mortality and increased serum FABP7 early (Log FABP7 Odds Ratio (OR) 1.16, P=0.32) and late (Log FABP7   OR 1.34, P=0.21) was not detected after adjusting for significant covariates (MELD, vasopressor use). Area under the receiver operating curve for early and late multivariable models were 0.760 and 0.892 respectively. A significant difference in FABP7 levels between patients with or without ICH/CE at early (259.7 vs. 228.2 ng/ml, P=0.61) and late (223.8 vs. 192.0 ng/ml, P=0.19) time points was not identified. FABP7 was not significantly associated with the development of ICH/CE after adjusting for significant covariates (Early OR 1.0, p=0.65; Late OR 1.0, p=0.57 see Table 1). Summary: Brain type FABP (FABP7) levels were elevated in APAP-ALF patients with serum significantly higher serum levels at early and late time points in APAP-ALF non-survivors. However, significant differences in FABP7 levels by 21-day mortality were not ascertained after adjusting for significant covariates reflecting severity of illness (MELD, vasopressor dependence). FABP7 did not discriminate between the APAP-ALF patients with and without ICH/CE. Conclusions: This suggests that while all APAP-ALF patients have some evidence of astrocyte inflammation and increased permeability in the blood brain barrier, FABP7 appears to not discriminate between patients who did and did not have significant intracranial complications of APAP-ALF. Disclosure: The study was sponsored by NIH grant U-01 58369 (from NIDDK), TL1 001451 (from NCATS), and a grant from the University of Alberta Hospital Foundation (UHF).

The liver plays a major role in regulating ammonia levels in the blood. Therefore, in liver disease the loss of hepatic function leads to hyperammonemia and increased brain ammonia and consequently hepatic encephalopathy (HE). Ammonia-lowering strategies remain the mainstay therapeutic strategy. Ammonia, both as an ion (NH4+) and gas (NH3), easily crosses all plasma membranes, including the blood brain barrier (BBB); the interface between the blood and the brain. Glutamine synthetase (GS), an enzyme which in the process of amidating glutamate to glutamine removes ammonia, plays an important compensatory role during liver disease. GS is expressed in muscle and brain (primarily in astrocytes) but has never been thoroughly explored in the BBB. Therefore, the aim is to evaluate GS expression in endothelial cells of the BBB. Using primary rat brain microvascular endothelial cells (ECs), the presence of GS was assessed using rtPCR, western blot, immunohistochemistry and activity assay. Furthermore, we isolated cerebral microvessels (CMV) from the frontal cortex of naïve rats and measured GS expression by western blot using brain lysates as positive control and by immunohistochemistry (co-localized with caveolin-1 (marker for ECs). In addition, to understand the effect of ammonia on GS, ECs were exposed to 1mM of ammonia chloride for 48h. Finally, ECs were subjected to plasma from bile-duct ligated (BDL) rats (model of chronic liver disease) or sham-operated controls. We have characterized this BDL model and found both systemic oxidative stress and inflammation, in addition to hyperammonemia. ECs expressed GS mRNA, protein and activity. However, expression of GS was lower compared to brain lysate control samples (p<0.05). GS expression in CMV showed similar results to brain but GS activity was less (p<0.05). Using immunohistochemistry, GS was detected in ECs and in vessels of brain from naïve rats. When cells were submitted to ammonia, an increase in GS activity was demonstrated (p<0.05). However, when exposed to conditioned medium from BDL rats, GS was decreased when compared to sham-operated controls (p<0.01). These results demonstrate for the first time that GS is present in ECs in both in vivo and in vitro. The lower expression of the enzyme compared to that found in the brain, could explain why GS has never been reported in these cells. Interestingly, ammonia stimulates GS in endothelial cells, but its activity is decreased in the presence of other pathogenic factors in plasma from cirrhotic rats such as oxidative stress and inflammation. We speculate that a downregulation of GS allows for a faster and easier entry of ammonia into the brain and therefore may be implicated in the pathogenesis of HE. We anticipate increasing GS in ECs of the BBB could become a new therapeutic target for HE.

The liver plays a major role in regulating ammonia levels in the blood. Therefore, in liver disease the loss of hepatic function leads to hyperammonemia and increased brain ammonia and consequently hepatic encephalopathy (HE). Ammonia-lowering strategies remain the mainstay therapeutic strategy. Ammonia, both as an ion (NH4+) and gas (NH3), easily crosses all plasma membranes, including the blood brain barrier (BBB); the interface between the blood and the brain. Glutamine synthetase (GS), an enzyme which in the process of amidating glutamate to glutamine removes ammonia, plays an important compensatory role during liver disease. GS is expressed in muscle and brain (primarily in astrocytes) but has never been thoroughly explored in the BBB. Therefore, the aim is to evaluate GS expression in endothelial cells of the BBB. Using primary rat brain microvascular endothelial cells (ECs), the presence of GS was assessed using rtPCR, western blot, immunohistochemistry and activity assay. Furthermore, we isolated cerebral microvessels (CMV) from the frontal cortex of naïve rats and measured GS expression by western blot using brain lysates as positive control and by immunohistochemistry (co-localized with caveolin-1 (marker for ECs). In addition, to understand the effect of ammonia on GS, ECs were exposed to 1mM of ammonia chloride for 48h. Finally, ECs were subjected to plasma from bile-duct ligated (BDL) rats (model of chronic liver disease) or sham-operated controls. We have characterized this BDL model and found both systemic oxidative stress and inflammation, in addition to hyperammonemia. ECs expressed GS mRNA, protein and activity. However, expression of GS was lower compared to brain lysate control samples (p<0.05). GS expression in CMV showed similar results to brain but GS activity was less (p<0.05). Using immunohistochemistry, GS was detected in ECs and in vessels of brain from naïve rats. When cells were submitted to ammonia, an increase in GS activity was demonstrated (p<0.05). However, when exposed to conditioned medium from BDL rats, GS was decreased when compared to sham-operated controls (p<0.01). These results demonstrate for the first time that GS is present in ECs in both in vivo and in vitro. The lower expression of the enzyme compared to that found in the brain, could explain why GS has never been reported in these cells. Interestingly, ammonia stimulates GS in endothelial cells, but its activity is decreased in the presence of other pathogenic factors in plasma from cirrhotic rats such as oxidative stress and inflammation. We speculate that a downregulation of GS allows for a faster and easier entry of ammonia into the brain and therefore may be implicated in the pathogenesis of HE. We anticipate increasing GS in ECs of the BBB could become a new therapeutic target for HE.

Learning Objectives: Acetaminophen (APAP) - induced Acute Liver Failure (ALF) is associated with significant mortality related to intracranial hypertension (ICH). Brain type fatty acid binding protein (B-FABP) is a small (15 kDa) cytoplasmic protein abundantly expressed in astrocytes where there is active fatty acid metabolism. B-FABP levels have not been previously reported in ALF patients at high risk of ICH. We aimed to determine whether serum B-FABP early (day 1) or late (day 3-5) levels were associated with 21-day mortality and/or the presence of ICH in APAP-ALF patients. Methods: Serum samples from 198 APAP-ALF patients (99 survivors, 99 non-survivors) were analyzed by ELIZA methods and assessed with clinical data from the US Acute Liver Failure Study Group (ALFSG) Registry (1998-2013). No patients received transplant in this analysis. Results: APAP-ALF survivors had significantly lower serum B-FABP levels on admission (147.9 vs. 316.5 ng/ml, P=0.0002) and late (87.3 vs. 286.2 ng/ml, P<0.0001) compared with non-survivors. However using multivariable logistic regression, a significant association between 21-day mortality and increased serum B-FABP early (Log B-FABP Odds Ratio (OR) 1.16, P=0.32) and late (Log L-FABP   OR 1.34, P=0.21) was not detected after adjusting for significant covariates (MELD, vasopressor use). Area under the receiver operating curve for early and late multivariable models were 0.760 and 0.892 respectively. In a second analysis where data were available, patients were stratified based on the presence of ICH (n=46) or absence (n=104) based on death summaries or clinical data (ICP monitor, computed tomography). A significant difference in B-FABP levels between patients with or without ICH at early (259.7 vs. 228.2 ng/ml, P=0.61) and late (223.8 vs. 192.0 ng/ml, P=0.19) time points was not identified. Conclusions: Serum B-FABP levels were significantly higher in APAP-ALF non-survivors but not after adjusting for covariates. While elevated B-FABP levels likely reflect astrocyte inflammation, B-FABP did not differentiate clinically between APAP-ALF patients with and without ICH.

Background: Acetaminophen (APAP)-induced acute liver failure (ALF) is associated with significant mortality. To date, prog- nostic scores lack discrimination in identifying patients who will die without liver transplant (LT), and those who will sur- vive with medical management. Liver-type fatty acid binding protein (L-FABP) is a 15 kDa cytoplasmic protein expressed in hepatocytes with potential prognostic value in APAP-ALF. Meth-ods: With serial serum samples (early; day 1 and late; day 3-5) from 198 APAP-ALF patients (99 survivors, 99 non-survi-vors), we examined whether L-FABP levels, measured using sol- id-phase enzyme-linked immunosorbent assay, were associated with 21-day mortality in the absence of LT. Results: APAP-ALF survivors had significantly lower L-FABP levels early (238.6 vs. 690.8 ng/ml, p<0.0001) and late (148.4 vs. 612.3 ng/ml, p<0.0001) compared with non-survivors (Fig 1). Using logistic regression, elevated L-FABP early (Log L-FABP Odds Ratio (OR) 1.31, p=0.027) and late (Log L-FABP OR 1.50, p=0.005) were associated with significantly increased 21-day mortality after adjusting for covariates (MELD, vasopressor use). Area under the receiver operating curve (AUROC) for early and late models were 0.778 and 0.907. The addition of L-FABP significantly improved (p<0.01) the AUROC of the King’s Col- lege Criteria (KCC) (Early: 0.552 alone, 0.711 with L-FABP; Late: 0.604 alone, 0.797 with L-FABP) as well as the ALFSG prognostic index (Early: 0.686 alone, 0.766 with L-FABP; Late: 0.711 alone, 0.815 with L-FABP). Conclusion: Serum L-FABP levels were significantly higher at serial time points in APAP-ALF non-survivors. After adjusting for covariates, serum L-FABP was significantly associated with 21-day mortality. L-FABP improved prognostic discrimination (AUROC) when combined with KCC and the ALFSG prognostic index which may potentially help identify APAP-ALF patients with higher potential of recovery.

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD, cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence on obesity affecting neurological function, we hypothesize that obesity increases the risk, severity and accelerates the progression of HE in non-alcoholic fatty liver disease (NAFLD)-related cirrhosis. AIM: To develop and characterize an animal model of cirrhosis and obesity to investigate the synergistic effect of obesity and CLD on the development of neurological impairment and HE. M&M: Animal model of CLD and obesity: The 6-week bile-duct ligation (BDL) rat is a surgical model in which obstruction of the bile duct leads to cirrhosis and HE. We induced obesity with a high-fat diet (HFD). Previously, HFD was given after BDL, but it was not well accepted, and the body weight did not increased. Now we are pre-feeding the rats with HFD to see if that is a better model. Thus, rats will be fed HFD for 3 weeks (pre-BDL) and 6 weeks post-BDL. Food consumption, weight gain, as well as lean vs fat mass will be monitored. Preliminary results: 3-week HFD increases body weight (12.1%) and fat (30.5 vs 44.1g) mass compared to rats fed normal diet. Food consumption was decreased (HFD 12g/day vs normal diet 27g/day), while the calorie intake was not affected. Discussion: obesity-induced cirrhosis in patients may result in more complex neurological manifestations, suggesting these patients might be more susceptible to neuronal loss and poor neurological performance. Thus, this animal model of CLD and obesity will give important clues about psychiatric diseases including, HE and how they might be treated. Funded: CIHR

Introduction: The liver plays a major role in regulating ammonia levels in the blood. During liver disease, loss of hepatic function leads to hyperammonemia and consequently neurotoxicity and hepatic encephalopathy. Ammonia (NH₄⁺ and NH₃) easily crosses cell membranes, including the blood brain barrier (BBB); the interface between the blood and the brain. Glutamine synthetase (GS), an enzyme which amidates glutamate to glutamine, removing ammonia, plays an important compensatory role during liver disease. GS is expressed in muscle and the brain (primarily in astrocytes) but ammonia metabolism in endothelial cells (EC) has never been thoroughly explored. Methods: Using primary rat brain microvascular endothelial cells, GS detection was performed by rtPCR, western blot, immunohistochemistry and activity assay . In addition we evaluated GS expression in cerebral microvessels (CMV) from frontal cortex of naive rats by immunohistochemistry and western blot. Results: ECs expressed GS mRNA, protein and activity, although less intense compared to muscle and liver (controls). In vivo results showed GS in vessels of brain slices (co-localized with caveolin ) and in CMV-enriched lysate. Discussion: We demonstrate the presence of GS in endothelial cells both in vivo and in vitro. We speculate GS in ECs could act as a first barrier against ammonia neurotoxicity and play a compensatory role in liver disease. However, the latter has yet to be investigated. We anticipate GS in EC’s has the potential to become a new therapeutic target for treating hyperammonemia in liver disease and other hyperammonemic syndromes. Project financed by CIHR MO financed by MITACS, Université de Montréal

Background: Malnutrition is one of the most common complication in the increasing number of patients suffering from chronic liver disease (cirrhosis; CLD) and is a leading cause of morbidity and mortality. Traditional tools used to evaluate nutritional status are not reliable in chronic liver disease due to limitations related to weight, which may be artificially increased by the presence of ascites, underestimating malnutrition. New strategies to assess nutritional status focussing on early malnutrition detection are an unmet clinical need. The aim of this ongoing pilot study is to describe the performance of different measures of nutrition including handgrip strength (HGS), mid-arm circumference (MAC) and subjective global assessment (SGA) in corre- lation to skeletal muscle index (SMI), an objective measure of skeletal muscle mass, among cirrhotic patients. Methods: In this ongoing pro- spective study, patients with and without CLD are recruited at the Centre hospitalier de l’Université de Montréal (St-Luc Hospital) in Can- ada. We assess nutritional status via: HGS as measured in the dominant hand with a calibrated dynamometer, MAC, SGA and SMI, as measured by computed tomography scan at the level of the third lumbar vertebrae. We also assess recommended and achieved calorie and protein intake. Spearman correlation coefficient is used to assess correlation between different tools. Results: To date, we recruited 21 patients with and 6 patients without CLD. Preliminary results indicate that SMI tends to correlate with HGS in both groups. Our prelim- inary results also suggest that SMI varies according to sex and etiology of cirrhosis. Discussion: The impact of age and sex of SMI needs fur- ther assessment. Objective measures of nutrition assessment in cirrhotics have the potential to reduce the dependence on subjective measures and allow accurate risk assessment. This may in turn lead to a change in clinical practice toward ensuring nutritional optimization in this high-risk population and attenuate CLD-related complications.

Background and Aims: Chronic liver disease (CLD) induces numerous complications including muscle mass loss and hepatic encephalopathy (HE) which negatively impact the clinical outcome. Furthermore, muscle mass wasting and HE have been shown to lead to poor prognosis following liver transplantation. Hyperammonemia is considered the central component in the pathogenesis of HE, however recent studies have suggested ammonia to be toxic to other organs besides the brain, such as the muscle. The aim of this study was to investigate the effect of ammonia on muscle mass in rats treated with an oral formulation of ornithine phenylacetate (OP; OCR-002). Methods: Six-week bile-duct ligated (BDL) and sham rats were used. OP was administered orally by gavage (1g/kg) daily for 5 weeks starting 1 week after surgery. Locomotor activity (day/night) was assessed in infrared beam cages for 24 h. Body weight, fat and lean mass (EchoMRI) were measured, followed by i.p. injection of a stable isotopes tracers cocktail in order to asses fractional synthesis of protein (FSR). Samples for blood ammonia, cerebral edema and muscle FSR were collected. Results: BDL rats demonstrated a 4-fold increase in blood ammonia vs sham-operated controls. This increase was reduced by 40% in OP-treated BDL rats. BDL rats gained less body weight compared to sham-operated controls (body weight of 360.2g ± 13.6 vs 476.8g ± 10.38 p<0.001) which was accompanied with a lower gain of lean mass and a lower muscle FSR. OP-treated BDL rats showed a significant increase in body weight (429.6g ± 117.9 p<0.001 vs BDL) with a significant higher lean mass (303.1g ± 10.7 in BDL+OP vs 264.4g ± 10.5 in BDL p<0.01). Fat mass remained unchanged between the treated and untreated BDL groups. OP treatment normalized brain water content in BDL rats. In contrast, OP-treatment reduced muscle FSR in SHAM animals, but not in BDL rats. Locomotor activity in BDL rats was reduced compared with sham-operated controls but no significant change was found between BDL+OP and SHAM+OP. Conclusions: This is the first study demonstrating the efficient ammonia-lowering effect of an oral formulation of OP. Long-term treatment with OP is a safe, non-antibiotic alternative demonstrating a significant ammonia-lowering effect, as well as a protective effect on the development of brain edema and muscle mass loss in rats with CLD. Whether the effect of OP on muscle mass loss attenuation is a result of lowering blood ammonia or directly improves muscle metabolism remains to be established.

Background: Chronic liver disease (CLD) induces numerous complications including muscle mass loss and hepatic encephalopathy (HE) which negatively impact the clinical outcome. Furthermore, muscle mass wasting and HE have been shown to lead to poor prognosis following liver transplantation. Hyperammonemia is considered the central component in the pathogenesis of HE, however recent studies have suggested ammonia to be toxic to other organs besides the brain, such as the muscle. Aims: The aim of this study was to investigate the effect of ammonia on muscle mass in rats treated with an oral formulation of ornithine phenylacetate (OP; OCR-002). Methods: Bile-duct ligated (BDL) rats were divided into 4 experimental groups; 1) Sham; 2) BDL; 3) Sham + OP; 4) BDL + OP. OP was administered orally by gavage (1g/kg) daily for 5 weeks starting 1 week after surgery. Two days before sacrifice, locomotor activity (day/night) was assessed in infrared beam cages for 24 h. The day of the sacrifice, body weight, fat and lean mass (EchoMRI) were measured, followed by i.p. injection of a stable isotopes tracers cocktail (Phe/Gly) in order to asses fractional synthesis of protein (FSR). At sacrifice, samples were collected to measure blood ammonia (commercial kit), cerebral edema (specific gravity method) and muscle FSR. Results : At 6-weeks, BDL rats demonstrated a 4-fold increase in blood ammonia vs Sham-operated controls. This increase was reduced by 40% in OP-treated BDL rats. Body weight decreased in BDL rats compared to sham-operated controls (360.2g±13.6 vs 476.8g±10.4; p<0.001) and significantly increased following OP-treatment (429.6g±117.9; p<0.001 vs BDL). This was due to a higher gain of lean mass in OP-treated BDL rats compared to BDL rats (303.1g±10.7 in BDL+OP vs 264.4g±10.5 in BDL, p<0.01). This was accompanied by increased muscle FSR in OP-treated BDL rats. Fat mass remained unchanged between treated and untreated BDL groups. OP treatment also normalized brain water content in BDL rats. Locomotor activity in BDL rats was reduced compared with sham-operated controls but no significant change was found between BDL+OP and SHAM+OP. Conclusions: This is the first study demonstrating the efficient ammonia-lowering effect of an oral formulation of OP. Moreover, OP long-term treatment is a safe, non-antibiotic alternative with protective effects on the development of cirrhosis complications such as HE and muscle mass loss in rats with CLD. Whether the effect of OP on muscle mass loss attenuation is a result of lowering blood ammonia or directly improves muscle metabolism remains to be established.

Background: Hepatic encephalopathy (HE) is a major neuropsychiatric complication caused by liver disease characterized by cognitive and motor dysfunction. Historically, HE has always been considered to be a reversible metabolic disorder and has therefore been expected to completely resolve following liver transplantation (LT). However, persisting neurological complications remain a common problem affecting as many as 47% of LT recipients. LT is a major surgical procedure accompanied by intraoperative stress, including blood loss and hypotension. Aim : We hypothesize, in the setting of minimal HE (MHE), the compromised brain becomes susceptible to hypotensive insults, resulting in cell injury and death. Methods: Six-week bile-duct ligated (BDL) rats with MHE and respective controls (SHAM) were used. Blood is withdrawn from the femoral artery (inducing hypovolemia) until a mean arterial pressure of 30, 60 and 90 mmHg (hypotension) and maintained for 120 minutes. Cerebral blood flow (BCF) was assessed by injecting fluorescent microspheres through the brachial artery. Upon sacrifice, brains were extracted for apoptotic analysis (western blot) and neuronal cell count (immunohistochemistry). In a separate group, BDL rats were treated for MHE with ornithine phenylacetate (OP; OCR-002), administered orally (1g/kg) for 3 weeks. Results: Both BDL rats and SHAM-operated controls without hypotension did not display any cell injury or neuronal loss. However, BDL rats following hypotension (30 and 60mmHg) demonstrated a significant decrease in neuronal cell count in the frontal cortex (using NeuN+DAPI and Cresyl Violet) compared to hypotensive SHAM-operated controls. In addition, neuronal loss was associated with an increased in cleaved caspase-3, suggesting apoptotic cell death. CBF decreased in BDL rats compared to SHAM and correlated with degree of hypotension insult. BDL rats treated with OP resulted in a decrease in blood ammonia and improvement in behaviour and did not lead to neuronal cell death following hypotension. Discussion: These findings strongly suggest that cirrhotic patients with MHE are more susceptible to hypotension-induced neuronal cell loss. Moreover, these results suggest a patient with HE (even MHE), with a “frail brain”, will fare worse during liver transplantation and consequently result in poor neurological outcome. Combination of MHE and hypotension may account for the persisting neurological complications observed in a number of cirrhotic patients following LT. Therefore, MHE, should not to be ignored and merits to be treated in order to reduce the risk of neurological complications occurring post-LT.

Introduction : L’encéphalopathie hépatique (EH) est une complication neuropsychiatrique sérieuse de la maladie hépatique chronique (cirrhose). La pathogénèse de l’EH serait attribuable, entre autres à l’ammoniac. L’accumulation de cette neurotoxine jouerait un rôle clé. De plus, la malnutrition est associée à un risque élevé de développer une perte sévère de masse musculaire et à l’EH; ces complications augmentent le risque de mortalité. La déficience en leucine, a été démontrée lors de cirrhose. La leucine sert de substrat énergétique et de précurseur pour d’autres acides aminés en plus de stimuler la synthèse protéique. De plus, l’expression de mammalian target of rapamycin (mTOR) et sa cible p70S6 kinase, deux protéines impliquées dans de nombreuses réactions en lien avec la survie cellulaire, serait altérée dans le muscle lors de maladie hépatique chronique. Une masse musculaire optimale lors d’EH contribuerait à réduire l’ammoniac via l’enzyme glutamine synthase (GS). L’hypothèse de recherche est que l’optimisation de la masse musculaire permet de prévenir/atténuer les épisodes d’EH. Matériel et méthode: Un modèle deligature des voies biliaires (BDL) chez le rat qui récapitule les caractéristiques de la cirrhose et de l’EH est utilisé. Cinq groupes sont évalués: 1) Contrôle avec simulation de la chirurgie (Sham); 2) BDL; 3) BDL+ Leucine; 4) BDL + Exercices; 5) BDL + Leucine + Exercices. Six semaines post-chirurgie, l’EH est vérifiée par des tests comportementaux et phénotypage neurologique. La masse musculaire est évaluée par imagerie par résonance magnétique. Les rats sont ensuite sacrifiés et les muscles sont prélevés. L’expression protéique de mTOR et de p70S6 kinase est mesurée par immunobuvardage. Résultats: Chez le groupe BDL, on remarque une baisse de la masse musculaire et de la synthèse protéique comparativement au groupe Sham. La supplémentation en leucine et l’exercice favorise une augmentation de la masse musculaire chez les rats BDL. La voie de signalisation via mTOR semble moins exprimée dans le muscle du groupe BDL versus Sham. Conclusion: Dans le but d’optimiser le statut nutritionnel et d’améliorer la qualité de vie des patients cirrhotiques atteints d’EH, des recherches plus approfondies devront être effectuées.

Introduction: L’encéphalopathie hépatique est une complication neuropsychiatrique causée par les maladies du foie. Ce syndrome devrait être réglé par la transplantation hépatique, mais d es complications neurologiques persistent chez près de 47% des p atients. La transplantation est accompagnée de stress intraopératoires dont l’hypovolémie et l’hypotension. Nous avons démontré qu’un cerveau fragilisé par l’encéphalopathie hépatique minimale (EHM) chez un rat cirrhotique devient plus susceptible à des dommages cérébraux causés par une hypotension, ce qui résulte en un stress cellulaire ainsi que la mort cellulaire neuronale. Ces signaux de stress cellulaire peuvent induire l’activation de la microglie, les cellules immunitaires du système nerveux central. Matériel et méthodes : Une hypotension par hypovolémie de l’artère fémorale a été effectuée pour atteindre une pression artérielle de 30 et 60 mmHg durant 2 heures chez des rats après 6 semaines suite à une cirrhose induite par ligation de la voie biliaire (BDL) et leu rs contrôles respectifs (SHAM). Nous avons évalué la présence de microglie activée dans le cortex frontal en immunobuvardage, avec CD11b, OX-42, CMH-II et COX-2 et en immunofluorescence, avec Iba-1. Résultats et discussion:Il n’y a pas d’activation microgliale chez les modèles SHAM et BDL dans le cortex préfrontal, mais l’insulte hypotensive induite chez le modèle cirrhotiqu e BDL, avec EHM , cause une activation de la microglie. Conclusion: L’activation microgliale chez les patients cirrhotiques soumis à une hypotension donne des outils supplémentaires dans la compréhension des processus pathophysiologiques délétères subséquents à une transplantation hépatique et permettra de suggérer des interventions cliniques afin de prévenir une aggravation des dommages cérébraux. Remerciements auCOPSE pour la bourse du Département de nutrition

Hyperammonemia can lead to cerebral dysfunction, encephalopathy, coma, and death if not treated adequately. The poor prognosis associated with this condition reflects the unmet medical need for effective ammonia-lowering treatments. Here, the translational potential of liposome-supported peritoneal dialysis (LSPD), a recently-developed detoxification strategy for the removal of small ionizable molecules like ammonia, is described. Dialysis fluids supplemented with micrometer-sized, transmembrane pH-gradient liposomes are prepared via an innovative, osmotic shock-based method overcoming sterilization and long-term stability issues. LSPD is able to sequester ammonia in healthy rats in relation to the injected dose, buffering capacity of the liposomal core, and membrane composition. In a rat model of cirrhosis, LSPD outperforms conventional peritoneal dialysis in lowering plasmatic ammonia levels and attenuating brain edema. LSPD does not trigger any hypersensitive reaction in pigs, a side effect commonly observed upon the injection of colloids in this animal model and in humans. These findings support the development of LSPD for the treatment of hyperammonemia-induced encephalopathy.

Background: Hepatic encephalopathy (HE) is a major neuropsychiatric complication caused by liver disease characterized by cognitive and motor dysfunction. The only curative treatment to date remains liver transplantation (LT). Historically, HE has always been considered to be a reversible metabolic disorder and has therefore been expected to completely resolve following LT. However, persisting neurological complications remain a common problem affecting as many as 47% of LT recipients. LT is a major surgical procedure accompanied by intraoperative stress and confounding factors, including blood loss and hypotension. We hypothesize, in the setting of minimal HE (MHE), the compromised brain becomes susceptible to hypotensive insults, resulting in cell injury and death. Methods: Six-week bile-duct ligated (BDL) rats with MHE and respective controls (SHAM) were used. Blood is withdrawn from the femoral artery (inducing hypovolemia) until an mean arterial pressure of 30 and 60 mmHg (hypotension) and maintained for 120 minutes. Cerebral blood flow (BCF) was assessed by injecting fluorescent microspheres (1x106 microspheres/ml) through the brachial artery. Upon sacrifice, brains were extracted for apoptotic analysis (western blot) and neuronal cell count (immunohistochemistry). In a separate group, BDL rats were treated for MHE with ornithine phenylacetate (OP; OCR-002) (1g/kg) for 3 weeks. Results: Both BDL rats and SHAM-operated controls without hypotension did not display any cell injury or neuronal loss. However, BDL rats following hypotension (30 and 60mmHg) demonstrated a significant decrease in neuronal cell count in the frontal cortex (using NeuN+DAPI and Cresyl Violet) compared to hypotensive SHAM-operated controls. In addition, neuronal loss was associated with an increased in cellular stress protein, hsp32, hsp70 and caspase-3, suggesting apoptotic cell death. CBF decreased in BDL rats compared to SHAM and correlated with degree of hypotension insult. BDL rats treated with OP did not lead to neuronal cell death following hypotension. Discussion: These findings strongly suggest that cirrhotic patients with MHE are more susceptible to hypotension-induced neuronal cell loss. Moreover, these results suggest a patient with HE (even MHE), with a “frail brain”, will fare worse during liver transplantation and consequently result in poor neurological outcome. Combination of MHE and hypotension may account for the persisting neurological complications observed in a number of cirrhotic patients following LT. Therefore, MHE, i) should not to be ignored and ii) deserves to be treated in order to reduce the risk of neurological complications occurring post-LT.

Background: Chronic liver disease (cirrhosis; CLD) is characterized by numerous metabolic disturbances which lead to complications that impact the clinical outcome. Among these, loss of muscle, characterized by a deterioration of muscle quantity and quality, leads to a decrease in functional capacity, adversely affecting survival, quality of life and outcome following liver transplantation. Hyperammonemia is central in the development of hepatic encephalopathy, a major complication of cirrhosis. However, it is speculated the toxic effect of ammonia extends beyond the brain, possibly affecting muscle. Therefore, we hypothesized that lowering blood ammonia will attenuate muscle mass loss in cirrhotic rats. Ornithine phenylacetate (OP; OCR-002) was used to lower blood ammonia. Methods: We induced CLD in rats following 6-week bile-duct ligation (BDL). Four experimental groups were tested; 1) Sham; 2) BDL; 3) Sham + OP; 4) BDL + OP. One week following BDL, rats were orally administered (gavage) OP (1g/kg) daily for 5 weeks. Body weight, fat and lean mass (EchoMRI), blood ammonia, cerebral edema (specific gravity method), fractional synthesis of protein (FSR) in muscle (with D2O) and locomotor activity (day/night) were measured. Results: At the end of the 6-weeks experiment, BDL rats demonstrated a 4-fold increase in blood ammonia vs Sham-operated controls. This increase was reduced by 40% in OP-treated BDL rats. BDL rats gained less body weight compared to sham-operated controls (body weight of 360.2g  13.6 vs 476.8g  10.38; p<0.001) which was accompanied with a lower gain of lean mass and a lower muscle FSR. OP-treated BDL rats showed a significant increase in body weight (429.6g  117.9; p<0.001 vs BDL) with a significant higher lean mass (303.1g  10.7 in BDL+OP vs 264.4g  10.5 in BDL, p<0.01). Fat mass remained unchanged between the treated and untreated BDL groups. OP treatment normalized brain water content in BDL rats. In contrast, OP-treatment reduced muscle FSR in SHAM animals, but not in BDL rats. Locomotor activity in BDL rats was reduced compared with sham-operated controls but no significant change was found between BDL+OP and SHAM+OP. Conclusion: This is the first study demonstrating the efficient ammonia-lowering effect of an oral formulation of OP. Long-term treatment with OP is a safe, non-antibiotic alternative demonstrating a significant ammonia-lowering effect, as well as a protective effect on the development of brain edema and muscle mass loss in rats with CLD. Whether the effect of OP on muscle mass loss attenuation is a result of lowering blood ammonia or directly improves muscle metabolism remains to be established.

Purpose: Hyperammonemia (HA) is a clinical condition characterized by toxic increases in systemic ammonia levels predominantly resulting from inherited or acquired impairments in hepatic detoxification (e.g. cirrhosis). If not treated, HA can lead to irreversible brain damages and death in severe cases. The poor prognosis associated to this condition reflects the still unmet clinical need for a safe, fast, and efficient ammonia-removal therapy. Hemodialysis, the current standard of care for treating severe HA, suffers indeed some major drawbacks as it is technically difficult to implement, not readily available in hospitals and highly risky for some patients (e.g., newborns and patients suffering from hemodynamic instability). Peritoneal dialysis (PD) may represent a valuable therapeutic alternative as it is a less invasive procedure since it uses the peritoneum as a semipermeable filter and the peritoneal cavity as a dialysis chamber. However, its clinical application is limited by its lower clearance capacity compared with hemodialysis. To address this problem, we report herein a novel dialysis fluid based on transmembrane pH-gradient liposomes (acidic core) that efficiently scavenge the excess of ammonia from the body. The ammonia-removal efficacy of this system was assessed in a rat model of cirrhosis induced by bile duct ligation. The cirrhotic rats develop hyperammonemia, and consequently brain edema. Methods: Liposome-supplemented peritoneal dialysis (LSPD) fluids (350 mOsm/L, pH 6.5), were prepared by sequentially mixing sterile liposomes aqueous suspensions, obtained by film hydration method, with a hypertonic acidic citrate buffer (pH 2) and an isotonic xylitol-based basic solution (pH 12.4). The first step allowed the encapsulation of an acidic medium in the vesicles core by means of an osmotic shock; the second established the transmembrane pH-gradient. Dose-response studies were first performed in healthy Sprague-Dawley rats by injecting LSPD fluids (60 mL/kg) with increasing liposome concentrations (4, 8 and 16 mM) in the peritoneal space, and evaluating their ammonia extraction efficiency over 4 h of dialysis. Efficacy studies were then performed in a rat model of secondary biliary cirrhosis induced by bile duct ligation. Control normal rats (SHAM) underwent a sham operation. Five weeks after the surgery, two different groups of cirrhotic rats (LSPD and PD) received 4 consecutive PDs performed every other day with LSPD or a conventional glucose-based PD solution (injected dose = 50 mL/kg). One group (positive control) did not receive any treatment. At the end of the study, the brain edema was assessed by measuring the brain water content in the frontal cortex by densitometry method. The ammonia concentration in dialysate and plasma samples was determined by enzymatic method using a commercial kit. Results: LSPD was shown to efficiently scavenge ammonia in the peritoneal space of healthy rats in a dose-dependent manner. The extracted ammonia levels progressively increased over time reaching a concentration of 0.48 ± 0.05 mM, 1.25 ± 0.2 mM and 1.72 ± 0.24 mM in fluids supplemented with liposomes 4, 8 and 16 mM, respectively. In light of these results, the LSPD fluid 8 mM, which exhibited a good ammonia uptake, was tested in a cirrhotic rat model. Compared to the control PD solution, the liposomal formulation showed an enhanced ammonia extraction capability. At the end of each dialysis session, the ammonia concentrations in the liposome-supplemented dialysate exceeded those obtained with the control solution by 7-fold. Importantly, this improved ammonia clearance led to a significant attenuation of the brain edema. Indeed after four consecutive LSPDs, the brain water content of cirrhotic rats was significantly decreased and reverted to normal levels. On the contrary, no significant reduction was observed with the control solution. Plasma ammonia levels were also found to significantly decrease after treatment with LSPD fluid but not with the control PD solution. Conclusion: These findings demonstrate that LSPD is a promising strategy to improve the clearance capacity of PD towards ammonia, and pave the way for a less invasive, safe and efficient approach for treating severe HA. Financial support from the Swiss Commission for Technology and Innovation (17525.1 PFLS-LS) is acknowledged.

Problématique : L’acidose lactique est une maladie mitochondriale rare causée par la mutation du gène LRPPRC (leucine-rich pentatricopeptide repeat motif containing). Elle est caractérisée principalement par une déficience tissu-spécifique (cerveau et foie) en cytochrome c oxydase, 4e complexe de la chaîne respiratoire ainsi que par des crises fatales d'acidose lactique. Il a été rapporté que ces crises, qui entraînent la mort de 80% des enfants atteints avant l’âge de 4 ans, sont déclenchées, entre autres, par une infection/inflammation et une surcharge nutritionnelle. À ce jour, aucun traitement n’existe pour prévenir ces crises. Question de recherche/objectif/hypothèse : Vérifier si la mutation rend les fibroblastes plus susceptibles au stress inflammatoire et nutritionnel. Méthodologie : Évaluer la viabilité des fibroblastes de peau de sujets contrôles (EBS) et de patients (AL), par microscopie à fluorescence, sous stress inflammatoire (TNF-α;100 ng/ml) et nutritionnel (palmitate; 0,5 mM) pour 24h. Les marqueurs Hoechst, caspase-3 et iodure de propidium ont été utilisés pour détecter les cellules viables, apoptotiques et nécrotiques, respectivement. Résultats : Nos résultats préliminaires démontrent qu’en conditions de stress, les taux de mort cellulaire par apoptose et nécrose semblent plus élevés dans les fibroblastes AL que les EBS. Discussion/conclusion/impact potentiel pour la nutrition : La mutation semble rendre les fibroblastes de patients atteints d’acidose lactique plus susceptibles au stress inflammatoire et nutritionnel. À plus long terme, l’appréciation du bienfait potentiel des acides gras oméga 3 dans ce processus pourrait s’avérer intéressante. Financement du projet / étudiant: Le Grand défi Pierre Lavoie.

L’acidose lactique est une maladie mitochondriale rare causée par la mutation du gène LRPPRC (leucine-rich pentatricopeptide repeat motif containing). Elle est caractérisée principalement par une déficience tissu-spécifique (cerveau et foie) en cytochrome c oxydase, 4e complexe de la chaîne respiratoire ainsi que par des crises fatales d'acidose lactique. Il a été rapporté que ces crises, qui entraînent la mort de 80% des enfants atteints avant l’âge de 4 ans, sont déclenchées, entre autres, par une infection/inflammation et une surcharge nutritionnelle. À ce jour, aucun traitement n’existe pour prévenir ces crises. Dans ce contexte, nous étudions l'impact d'un stress inflammatoire et nutritionnel en utilisant des fibroblastes de peau de sujets contrôles (EBS) et de patients atteints d’acidose lactique (AL). L’objectif général du projet est de vérifier si la mutation du gène LRPPRC rend les fibroblastes plus susceptibles dans des conditions de stress inflammatoire et nutritionnel. À cet effet, la viabilité des fibroblastes est évaluée par microscopie à fluorescence dans les conditions de stress inflammatoire et nutritionnel telles que « tumor necrosis factor alpha » (TNF-α) à 100ng/ml et palmitate à 1mM, et ce, à différentes périodes d’incubation. Les marqueurs Hoechst, caspase-3 et iodure de propidium ont été utilisés pour détecter les cellules viables, apoptotiques et nécrotiques, respectivement. Nos résultats préliminaires démontrent qu’en conditions de stress, les taux de mort cellulaire par apoptose et nécrose semblent plus élevés dans les fibroblastes AL que les EBS. La mutation semble rendre les fibroblastes de patients atteints d’acidose lactique plus susceptibles au stress inflammatoire et nutritionnel. À plus long terme, l’appréciation du bienfait potentiel des acides gras oméga 3 dans ce processus pourrait s’avérer intéressante.

Introduction L’encéphalopathie hépatique (EH) est une complication neuropsychiatrique causée par les maladies du foie. Ce syndrome est considéré comme un désordre métabolique réversible, qui devrait être réglé par la transplantation hépatique (TH), cependant les complications neurologiques persistent chez près de 47% des patients. La TH est une procédure accompagnée de stress intra-opératoires dont l’hypovolémie et l’hypotension. Nous supposons que le cerveau fragilisé devient plus susceptible à une hypotension, résultant en un stress ainsi que la mort cellulaire. Méthodologies Une hypotension par hypovolémie de l’artère fémorale est effectuée pour atteindre une pression artérielle de 30mmHg durant 2 heures chez des rats de 6 semaines avec ligation de la voie biliaire (BDL) et leurs contrôles respectifs (SHAM). Les cerveaux sont prélevés pour immunobuvardage et immunohistochimie. Résultats Les rats BDL avec hypotension ont démontré une diminution du compte neuronal dans le cortex préfrontal en utilisant NeuN+DAPI et le Crésyl violet, comparativement aux contrôles SHAM hypotendus. De plus, la protéine de stress cellulaire HSP32 est augmentée chez les groupes BDL hypotendus, tout comme la caspase-3 clivée, suggérant une mort cellulaire par apoptose. Les groupes contrôles sans hypotension ne démontrent aucune perte neuronale avec les marqueurs précédents. Discussion Ces résultats démontrent que les patients atteints d’EH sont plus susceptibles à une insulte hypotensive induisant une mort neuronale, et peuvent expliquer pourquoi certains patients ayant reçu une TH expérimentent des complications neurologiques.

Background: Hepatic encephalopathy (HE) is a major neuropsychiatric complication caused by liver disease characterized by cognitive and motor dysfunction. The only curative treatment to date remains liver transplantation (LT). Historically, HE has always been considered to be a reversible metabolic disorder and has therefore been expected to completely resolve following LT. However, even following the implantation of a new liver, persisting neurological complications remain a common problem affecting as many as 47% (8 47%) of liver transplant recipients. LT is a major surgical procedure accompanied by intraoperative stress and confounding factors, including blood loss (hypovolumia) and hypotension. We hypothesize, in the setting of MHE, that the compromised brain becomes predisposed to what would normally be an innocuous hypotensive insult, resulting in cell injury and death. Methods: Six-week bile-duct ligated (BDL) rats with MHE and respective controls will be used. Blood is withdrawn from the femoral artery (inducing hypovolemia) until an arterial pressure of 30 mmHg (hypotension) and maintained for 150 minutes. Upon sacrifice, brains are perfused and extracted for apoptotic analysis (western blot) and neuronal cell count (immunohistochemistry). Results: Both BDL rats and SHAM-operated controls without hypotension do not display any neuronal loss. However, BDL rats following hypotension demonstrated a significant decrease in neuronal cell count in the frontal cortex using NeuN+DAPI and Cresyl Violet compared to hypotensive SHAM-operated controls. In addition, neuronal loss was associated with an increased in cellular stress protein, hsp32, hsp70 and caspase-3, suggesting apoptotic cell death. Discussion: These findings suggest that patients with MHE are more susceptible to hypotension-induced neuronal cell loss. Moreover, these results suggest a patient with HE (even MHE), with a “frail brain”, will fare worse during LT and consequently result in poor neurological outcome. The combination of MHE and hypotension may justify for the persisting neurological complications observed in a number of cirrhotic patients following LT. This implies the impact of MHE on outcome is undervalued. MHE should not to be ignored and patients with MHE merit to be treated pre-LT.

Problématique : L’acidose lactique est une maladie mitochondriale rare causée par la mutation du gène LRPPRC (leucine-rich pentatricopeptide repeat motif containing). Elle est caractérisée principalement par une déficience tissu-spécifique (cerveau et foie) en cytochrome c oxydase, 4e complexe de la chaîne respiratoire ainsi que par des crises fatales d'acidose lactique. Il a été rapporté que ces crises, qui entraînent la mort de 80% des enfants atteints avant l’âge de 4 ans, sont déclenchées, entre autres, par une infection/inflammation et une surcharge nutritionnelle. À ce jour, aucun traitement n’existe pour prévenir ces crises. Question de recherche/objectif/hypothèse : Vérifier si la mutation rend les fibroblastes plus susceptibles au stress inflammatoire et nutritionnel. Méthodologie : Évaluer la viabilité des fibroblastes de peau de sujets contrôles (EBS) et de patients (AL), par microscopie à fluorescence, sous stress inflammatoire (TNF-α;100 ng/ml) et nutritionnel (palmitate; 0,5 mM) pour 24h. Les marqueurs Hoechst, caspase-3 et iodure de propidium ont été utilisés pour détecter les cellules viables, apoptotiques et nécrotiques, respectivement. Résultats : Nos résultats préliminaires démontrent qu’en conditions de stress, les taux de mort cellulaire par apoptose et nécrose semblent plus élevés dans les fibroblastes AL que les EBS. Discussion/conclusion/impact potentiel pour la nutrition : La mutation semble rendre les fibroblastes de patients atteints d’acidose lactique plus susceptibles au stress inflammatoire et nutritionnel. À plus long terme, l’appréciation du bienfait potentiel des acides gras oméga 3 dans ce processus pourrait s’avérer intéressante. Financement du projet / étudiant: Le Grand défi Pierre Lavoie.

Background: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (cirrhosis; CLD). Malnutrition exacerbates severe muscle loss and hepatic encephalopathy (HE) in cirrhotic patients. New management strategies focussing on improving nutritional status and attenuating CLD-related complications are an unmet clinical need. Aims: We hypothesize supplementation with branched-chain amino acid leucine (LEU) and exercise training (EX) could possibly attenuate muscle mass loss and prevent HE (characterized by brain edema as well as cognitive and psychomotor impairments) in CLD. Methods: CLD was induced in rats following 6-week bile-duct ligation (BDL). Five experimental groups were tested; 1) BDL; 2) BDL + LEU; 3) BDL + EX; 4) BDL + LEU + EX; 5) Sham-operated rats. One week following BDL, rats were submitted to 15 min EX (10 cm/s) every other day and BDL rats receiving LEU, were gavaged daily (1.35 mg/kg) for five weeks. Body weight, muscle (gastrocnemius) mass, metabolic state (calculation of energy expenditure independent of food intake and fecal mass), cerebral edema (specific gravity method) and cognitive/psychomotor function (open-field test; anxiety-like behavior assessment and novel object recognition test; memory testing) were measured in all groups. Results: BDL rats gained less body weight compared to sham-operated rats (125.0±24.9 g vs 226.0±38.5 g; P<0.05). LEU-treated BDL rats display an improvement in brain edema (78.50±0.03% vs 80.27±0.14%; P<0.05), muscle mass (5.48±0.90 g/kg vs 4.83±0.11 g/kg; P<0.05) and circumference (15.6±0.8 cm/kg vs 13.1±0.7 cm/kg ; P<0.05) and metabolic activity (27.48±1.15 vs 32.99±2.35; P<0.05), which was further ameliorated with EX, compared to BDL animals. In addition, BDL rats receiving LEU and EX exhibited less anxiety-like behavior (4.9±1.2 s vs 2.2±0.9 s passed in the center; P<0.01) as well as better novel object recognition memory (69.6±15.2% vs 25.4±9.6%; P<0.01), in comparison with BDL rats. Conclusions: Our results demonstrate that supplemental LEU along with EX reduces body weight and muscle mass loss, improves metabolic activity, attenuates brain edema and improve cognitive and psychomotor function. These findings suggest that strategies aiming at improving nutritional status will attenuate muscle mass loss, reduce the risk of developing HE and therefore improve quality of life and decrease mortality in CLD. LEU supplementation and EX could rapidly be translated into clinical practice. Funding Agency: CIHR.

Background: Hepatic encephalopathy (HE) is a major neuropsychiatric complication caused by liver disease characterized by cognitive and motor dysfunction. The only curative treatment to date remains liver transplantation (LT). Historically, HE has always been considered to be a reversible metabolic disorder and has therefore been expected to completely resolve following LT. However, even following the implantation of a new liver, persisting neurological complications remain a common problem affecting as many as 47% (8 47%) of liver transplant recipients. LT is a major surgical procedure accompanied by intraoperative stress and confounding factors, including blood loss (hypovolumia) and hypotension. We hypothesize, in the setting of MHE, that the compromised brain becomes predisposed to what would normally be an innocuous hypotensive insult, resulting in cell injury and death. Methods: Using 6-week bile-duct ligated rats and respective controls, blood is withdrawn from the femoral artery (inducing hypovolemia) until an arterial pressure of 30 mmHg (hypotension) and maintained for 150 minutes. Upon sacrifice, brains are perfused and extracted for western blotting and immunohistochemistry. Results: Both BDL rats and SHAM-operated controls without hypotension do not display any neuronal loss. However, BDL rats following hypotension demonstrated a significant decrease in neuronal cell count in the frontal cortex using NeuN+DAPI and Cresyl Violet compared to hypotensive SHAM-operated controls. In addition, neuronal loss was associated with an increased in cellular stress protein, hsp32 and caspase-3, suggesting apoptotic cell death. Discussion: These findings suggest that patients with HE are more susceptible to hypotension-induced neuronal cell loss and this may explain why transplanted patients are experiencing persisting neurological complications. Aside from cirrhotic patients having a stroke, these results also suggest a patient with HE (even MHE) with a “frail brain”, fare worse during transplantation leading to poor neurological outcome. This implies MHE should not be ignored and therefore treated pre-LT.

Introduction L’encéphalopathie hépatique (EH) est une complication neuropsychiatrique causée par les maladies du foie. Ce syndrome est considéré comme un désordre métabolique réversible, qui devrait être réglé par la transplantation hépatique (TH), cependant les complications neurologiques persistent chez près de 47% des patients. La TH est une procédure accompagnée de stress intra-opératoires dont l’hypovolémie et l’hypotension. Nous supposons que le cerveau fragilisé devient plus susceptible à une hypotension, résultant en un stress ainsi que la mort cellulaire. Méthodologies Une hypotension par hypovolémie de l’artère fémorale est effectuée pour atteindre une pression artérielle de 30 mmHg durant 2 heures chez des rats de 6 semaines avec ligation de la voie biliaire (BDL) et leurs contrôles respectifs (SHAM). Les cerveaux sont prélevés pour immunobuvardage et immunohistochimie. Résultats Les rats BDL avec hypotension ont démontré une diminution du compte neuronal dans le cortex préfrontal en utilisant NeuN+DAPI et le Crésyl violet, comparativement aux contrôles SHAM hypotendus. De plus, la protéine de stress cellulaire HSP32 était augmentée chez les groupes BDL hypotendus, tout comme la caspase-3 clivée, suggérant une mort cellulaire par apoptose. Les groupes contrôles SHAM et BDL sans hypotension ne démontrent aucune perte neuronale avec les marqueurs précédents.

Introduction: Le Syndrome de Leigh version canadienne française (LSFC) ou «acidose lactique» est une maladie mitochondriale rare causée par la mutation du gène LRPPRC (leucine-rich pentatricopeptide repeat motif containing). Elle est caractérisée principalement par une déficience tissu-spécifique (cerveau et foie) en cytochrome c oxydase de la chaîne respiratoire ainsi que par des crises fatales d'acidose lactique. Celles-ci sont déclenchées, entre autres, par l'infection/inflammation et la surcharge nutritionnelle. À ce jour, aucun traitement n'existe pour les prévenir et l'identification d'un modèle expérimental de stress inflammatoire et nutritionnel est essentiel afin d'élucider les mécanismes par lesquels la mutation affecte les cellules LSFC. Méthodes: Nous avons évalué la viabilité des fibroblastes de peau de sujets contrôles et de patients atteints d'acidose lactique par Resazurin dans différentes conditions de stress inflammatoire et nutritionnel, telles que LPS (2 μg/ml), TNF-α (100 ng/ml) et palmitate (1 mM), et ce, à différentes périodes d'incubation (0, 24, 48 et 72h). Résultats: Une diminution significative (p<0,001) de la viabilité cellulaire a été observée 48h après l'exposition de palmitate ou en combinaison avec TNF-α. De plus, une tendance à une susceptibilité accrue au stress est notée dans les fibroblastes de patients LSFC. Discussion/Conclusion: Le stress inflammatoire et nutritionnel semble influencer la viabilité des fibroblastes de patients LSFC. À plus long terme, la modulation de la réponse cellulaire par des agents «thérapeutiques» incluant les acides gras oméga 3, pourrait s'avérer intéressante.

Background: Brain edema is a serious complication associated with hepatic encephalopathy (HE) due to chronic liver disease (CLD). An increase in blood brain barrier (BBB) ion permeability can occur across an intact BBB through alterations in transport mechanisms. NH4+ has very similar ionic properties to K+ and can be transported through K+ channels and cotransporters, implying that hyperammonemia could result in BBB hyperpermeability. An increase in BBB permeability via transport Na+-K+-2Cl- (NKCC1) has shown to promote brain edema and astrocyte swelling under pathophysiological conditions such as ischemia. Aim: To study the BBB integrity (vasogenic vs cytotoxic) and the role of NKCC1 in the pathogenesis of brain edema in cirrhotic rats. Methods: Two distinct animal models of HE are used in the present study; 1) biliary cirrhosis model (6 weeks bile duct ligation (BDL)). 2) portacaval shunt model (4 weeks portacaval anastomosis (PCA)). Both models develop hyperammonemia however brain edema is only observed in BDL. BBB breakdown was assessed by measuring brain extravasation of Evans blue and sodium fluorescein (injected i.v). Expression of BBB tight junction proteins (occludin, claudin-5, ZO-1 and ZO-2) were assessed by Western blot. Bumetanide was administered (i.p) for 10 days in BDL and SHAM animals. Brain water content was measured in the frontal cortex using the specific gravimetric method. Levels of brain NKCC1 mRNA were evaluated by RT-PCR in cerebral microvessels. Results: Extravasation of Evans blue and sodium fluorescein was not detected and no significant change in all tight junction protein was observed in both BDL and PCA models. Brain water content was reduced in bumetanide-treated BDL rats compared to control (77.66±0.15% vs 78.12±0.21%). In brain microvessels, NKCC mRNA increased in BDL rats compared to BDL SHAM (0.78±0.09 vs. 1.92±0.42) whereas no change was found in PCA compared to PCA SHAM (1.72±0.52 vs. 1.53±0.23). Conclusions: BDL rats did not demonstrate a change in BBB integrity or expression of tight junction proteins concluding brain edema in BDL is not of vasogenic origin. Furthermore, since brain edema was only observed in BDL rats (vs PCA), this implies additional factors aside ammonia, are involved in the pathogenesis of brain edema. Moreover, an increase of NKCC1 mRNA and an attenuation of brain edema following bumetanide treatment were demonstrated in BDL rats suggesting NKCC1 plays a role in the development of brain edema in CLD. These results demonstrate the potential therapeutic use of bumetanide for the treatment of HE.

Background: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (cirrhosis; CLD). Malnutrition, considered a consequence of metabolic disturbances (hypermetabolism), exacerbates severe muscle loss and hepatic encephalopathy (HE) (complex neuropsychiatric disorder) in cirrhotic patients. New management strategies focussing on improving nutritional status and attenuating CLD-related complications are an unmet clinical need. We hypothesize supplementation with branched-chain amino acid leucine (LEU) and exercise training (EX) could possibly attenuate muscle mass loss and prevent HE (characterized by brain edema as well as cognitive and psychomotor impairments) in CLD. Methods: CLD was induced in rats following 6-week bile-duct ligation (BDL). Five experimental groups were tested; 1) BDL; 2) BDL + LEU; 3) BDL + EX; 4) BDL + LEU + EX; 5) Sham-operated rats. One week following BDL, rats were gavaged with LEU (1.35 mg/kg) daily and submitted to 15 min EX (10 cm/s) every other day for 5 weeks. Body weight, muscle (gastrocnemius) mass, metabolic state (calculation of energy expenditure independent of food intake and fecal mass), cerebral edema (specific gravity method) and cognitive/psychomotor function (open-field test; anxiety-like behavior assessment and novel object recognition test; memory testing) were measured. Results: BDL rats gained less body weight compared to sham-operated rats (125.0g ± 24.9 vs 226.0g ± 38.5; p<0.05). LEU-treated BDL rats display an improvement in brain edema (78.50% ± 0.03 vs 80.27% ± 0.14; p<0.05), muscle mass (5.48g/kg ± 0.90 vs 4.83g/kg ± 0.11; p<0.05) and circumference (15.6cm/kg ± 0.8 vs 13.1cm/kg ± 0.7; p<0.05) and metabolic activity (27.48 ± 1.15 vs 32.99 ± 2.35; p<0.05), which was further ameliorated with EX, compared to BDL animals. In addition, BDL rats receiving LEU and EX exhibited less anxiety-like behavior (4.9s ± 1.2 vs 2.2s ± 0.9 passed in the center; p<0.01) as well as better novel object recognition memory (69.6 ± 15.2% vs 25.4 ± 9.6%; p<0.01), in comparison with BDL rats. Conclusion: Our results demonstrate that supplemental LEU along with EX recovers body weight loss, increases muscle mass, improves metabolic activity, attenuates brain edema and improves cognitive and psychomotor function. These findings suggest that strategies aiming at improving nutritional status will attenuate muscle mass loss and reduce the risk of developing HE. This in turn will improve quality of life, decrease mortality and enhance outcome post-liver transplantation. LEU supplementation and EX could rapidly be translated into clinical practice.

Background: Brain edema is a serious complication associated with hepatic encephalopathy (HE) due to chronic liver disease. An increase in BBB ion permeability (increase uptake of ions and accompanied by water fluxes towards the brain) can occur across an intact BBB through alterations in transport mechanisms. Endothelial cells that comprise the BBB secrete up to 40% of brain interstitial fluid as they transport Na+, K+ and 2 Cl- across the BBB. NH4+ has very similar ionic properties to K+ (similar ionic radius and diffusion coefficient) and can be transported through K+ channels and cotransporters, implying that hyperammonemia could result in BBB hyperpermeability. An increase in BBB permeability via transport Na+-K+-2Cl- (NKCC1) has shown to promote brain edema and astrocyte swelling under pathophysiological conditions such as ischemia. Aim: To study the BBB integrity (vasogenic vs cytotoxic) and the role of NKCC1 in the pathogenesis of brain edema in cirrhotic rats. Methods: Two distinct animal models of chronic liver failure and HE are used in the present study; 1) biliary cirrhosis model (6 weeks bile duct ligation (BDL)). 2) portacaval shunt model (4 weeks portacaval anastomosis (PCA)). Both models develop hyperammonemia however brain edema is only observed in BDL. BBB breakdown was assessed by measuring brain extravasation of Evans blue and sodium fluorescein (injected i.v). Expression of BBB tight junction proteins (occludin, claudin-5, ZO-1 and ZO-2) were assessed by Western blot. Bumetanide was administered (i.p) for 10 days in BDL and BDL SHAM. Brain water content was measured in the frontal cortex using the specific gravimetric method. Levels of brain NKCC1 mRNA were evaluated by RT-PCR in cerebral microvessels. Results: Extravasation of Evans blue and sodium fluorescein was not detected and there was no significant change in all tight junction protein levels measured in both BDL and PCA models. Brain water content was reduced in bumetanide-treated BDL rats compared to control (77.66±0.15% vs 78.12±0.21%). In brain microvessels, NKCC mRNA increased in BDL rats compared to BDL SHAM (0.78±0.09 vs. 1.92±0.42) whereas no change was found in PCA compared to PCA SHAM (1.72±0.52 vs. 1.53±0.23). Conclusions: BDL rats did not demonstrate a change in BBB integrity or in expression of BBB tight junction proteins. This suggests brain edema in BDL is not of vasogenic origin. Furthermore, since brain edema was only observed in BDL rats (vs PCA), this implies additional factors aside ammonia, are involved in the pathogenesis of brain edema. Moreover, an increase of NKCC1 mRNA and an attenuation of brain edema following bumetanide treatment were demonstrated in BDL rats suggesting NKCC1 plays a role in the development of brain edema in chronic liver disease. Furthermore, these results demonstrate the potential therapeutic use of bumetanide for the treatment of HE.

Background: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (cirrhosis; CLD). Malnutrition, considered a consequence of metabolic disturbances (hypermetabolism), exacerbates severe muscle loss and hepatic encephalopathy (complex neuropsychiatric disorder) in cirrhotic patients. New management strategies focussing on improving nutritional status and attenuating CLD-related complications are an unmet clinical need. We hypothesize supplementation with branched-chain amino acid leucine (LEU) and exercise training (EX) could possibly attenuate muscle mass loss and prevent hepatic encephalopathy (characterized by brain edema as well as cognitive and psychomotor impairments) in CLD. Methods: CLD was induced in rats following 6-week bile-duct ligation (BDL). Five experimental groups were tested; 1) BDL; 2) BDL + LEU; 3) BDL + EX; 4) BDL + LEU + EX; 5) Sham-operated rats. One week following BDL, rats were submitted to 15 min EX (10 cm/s) every other day and BDL rats receiving LEU, were gavaged daily (1.35 mg/kg) for 5 weeks. Body weight, muscle (gastrocnemius) mass, metabolic state (calculation of energy expenditure independent of food intake and fecal mass), cerebral edema (specific gravity method) and cognitive/psychomotor function (open-field test; anxiety-like behavior assessment and novel object recognition test; memory testing) were measured in all groups. Results: BDL rats gained less body weight and muscle mass compared to sham-operated rats. LEU-treated BDL rats display an improvement in brain edema, muscle mass and circumference and metabolic activity, which was further ameliorated with EX. In addition, BDL rats receiving LEU and EX exhibited less anxiety-like behavior as well as better novel object recognition memory. Conclusion: Our results demonstrate that supplemental LEU along with EX reduces body weight and muscle mass loss, improves metabolic activity, attenuates brain edema and improve cognitive and psychomotor function. These findings suggest that strategies aiming at improving nutritional status will attenuate muscle mass loss, reduce the risk of developing hepatic encephalopathy and therefore improve quality of life and decrease mortality in CLD. LEU supplementation and EX could rapidly be translated into clinical practice.

Background: Hepatic encephalopathy (HE) is a major neuropsychiatric complication caused by liver disease characterized by cognitive and motor dysfunction. The only curative treatment to date remains liver transplantation (LT). Historically, HE has always been considered to be a reversible metabolic disorder and has therefore been expected to completely resolve following LT. However, even following the implantation of a new liver, persisting neurological complications remain a common problem affecting as many as 47% (8 47%) of liver transplant recipients. LT is a major surgical procedure accompanied by intraoperative stress and confounding factors, including blood loss (hypovolumia) and hypotension. We hypothesize, in the setting of MHE, that the compromised brain becomes predisposed to what would normally be an innocuous hypotensive insult, resulting in cell injury and death. Methods: Using 6-week bile-duct ligated rats and respective controls, blood is withdrawn from the femoral artery (inducing hypovolemia) until an arterial pressure of 30 mmHg (hypotension) and maintained for 150 minutes. Upon sacrifice, brains are perfused and extracted for western blotting and immunohistochemistry. Results: Both BDL rats and SHAM-operated controls without hypotension do not display any neuronal loss. However, BDL rats following hypotension demonstrated a significant decrease in neuronal cell count in the frontal cortex using NeuN+DAPI and Cresyl Violet compared to hypotensive SHAM-operated controls. In addition, neuronal loss was associated with an increased in cellular stress protein, hsp32, hsp70 and caspase-3, suggesting apoptotic cell death. Discussion: These findings suggest that patients with HE are more susceptible to hypotension-induced neuronal cell loss and this may explain why transplanted patients are experiencing persisting neurological complications. Aside from cirrhotic patients having a stroke, these results also suggest a patient with HE (even MHE) with a “frail brain”, fare worse during transplantation leading to poor neurological outcome. This implies MHE should not be ignored and therefore treated pre-LT.

Background: Ammonia plays a major role in the pathogenesis of hepatic encephalopathy (HE) and therefore ammonia-lowering treatments remain a primary therapeutic strategy. Glutamine deamidation by the mitochondrial enzyme glutaminase (GLS) is believed to a major source of ammonia production in cirrhotic patients and increased intestinal GLS activity has been shown to be linked to minimal HE and to an increased risk of developing overt HE. CB-839 is a potent, selective and orally bioavailable GLS inhibitor (Gross et al., Mol Cancer Ther 13:890) that is currently in Phase 1 clinical trials for the treatment of cancer (clinicaltrials.gov). Aim: To evaluate the effect of CB-839, a GLS inhibitor, in preventing the onset of hyperammonemia following an oral glutamine challenge (OGC) in rats with portacaval anastomosis (PCA). Methods: Four week PCA rats received a single dose of CB-839 (gavage, 200 mg/kg diluted in 5ml/kg of vehicle). Control PCA rats received equivalent volumes of vehicle. Four hours after CB-839 or vehicle administration, PCA rats received an oral glutamine challenge (gavage, 100 mg/kg). Repeated aortic blood samples were obtained at baseline, 0.5h, 1h, 1.5h, 2.5h, 2.5h, 3h and 4h following OGC. Glutamine and ammonia were measured using commercial available kits. Results: Baseline ammonia levels were similar in both PCA groups. Following OGC, blood ammonia increased in vehicle-treated PCA rats with a peak at 2h (2.3-fold increase vs baseline, p<0.05). In CB-839 treated-PCA rats, ammonia levels did not change compared to the baseline value and were significantly decreased compared to non-treated PCA rats (p<0.05). At 4h, ammonia levels returned to baseline values in both groups. Baseline glutamine levels were not significantly different between treated and non-treated PCA rats. Following OGC, no significant difference between glutamine levels was observed in non-treated PCA rats compared to baseline values. However, in PCA rats treated with CB-839 glutamine levels significantly increased compared to non-treated PCA controls attaining a peak at 2.5 h (1.59 ± 0.40 mM vs 0.60 ± 0.15 mM, p<0.05). At 4h, glutamine levels remained significantly increased. Conclusions: CB-839 treatment inhibited glutamine induced hyperammonemia in PCA rats. These preliminary results strongly suggest CB-839 is an effective agent to attenuate GLS-induced ammonia production. Further studies are warranted to evaluate CB-839 as a novel agent for the treatment of HE.

Hepatic encephalopathy is a neuropsychiatric disorder; a major complication of liver disease. Impairment in liver function leads to a reduced capacity to clear ammonia (via urea cycle) and subsequently hyperammonemia arises. The consequent neurotoxic levels of ammonia are considered to play a major role in the pathogenesis of hepatic encephalopathy. However, a correlation between ammonia and severity of neurological impairment is poor. Oxidative stress is another factor believed to play a role in the pathogenesis of this syndrome as it has demonstrated to exacerbate the neuropsychological effects of hyperammonemia. In the setting of liver disease, oxidative stress represents a systemic phenomenon induced by several mechanisms: decreased antioxidant synthesis, increased systemic release of oxidant enzymes, generation of reactive oxygen species and impaired neutrophil function. Furthermore, it has been demonstrated that high ammonia concentrations can induce oxidative stress. However, significantly lower degrees of hyperammonemia (<500 µM) are observed in patients with end-stage liver disease (cirrhosis), concentrations which do not induce cerebral nor systemic oxidative stress. Therefore defining ammonia and oxidative stress as independent factors. Data from both animal and human studies strongly suggest there is a synergistic effect between systemic oxidative stress and ammonia in the pathogenesis of hepatic encephalopathy and that induction of cerebral oxidative stress may be associated with severe neurological symptoms.

L’encéphalopathie hépatique (EH) est une complication majeure des maladies du foie caractérisée par des troubles cognitifs, moteurs et psychiatrique qui peuvent mener jusqu’au coma et la mort. La transplantation du foie reste présentement la seule option curative de la maladie. Des études récentes ont démontré que la présence d’EH avant la transplantation est reliée aux complications neurologiques survenant après l’intervention. Le cerveau demandant plus de 20% de la demande énergétique du corps, l’hypotension et la perte sanguine associée à l’opération pourraient être responsables de ces dommages neurologiques, puisque l’apport sanguin au cerveau est réduit, particulièrement chez les cerveaux déjà fragilisés par l’EH. L’objectif principal de mon projet de maîtrise est de caractériser l’impact de l’EH sur la mort neuronale causée par une hypotension, induite par hypovolémie, chez des rats dont la cirrhose est causée par la ligation chirurgicale de la voie biliaire (BDL). Les animaux développent entre autres, une jaunisse, une hyperammonémie, des difficultés motrices, de mémoire et un œdème cérébral, étant des symptômes typiques de la cirrhose associés à l’EH. Les rats seront soumis à une hypotension de différentes sévérités et durées en induisant une hypovolémie. Le cerveau sera par la suite prélevé pour identifier les dommages neurologiques par immunohistochimie dus à la mort cellulaire. La mort cellulaire sera déterminée, par le Fluoro-Jade et le crésyl violet. Le TUNEL et l’activation des caspases nous permettra d’évaluer l’apoptose. J’ai mis aux points les tests d’immunobuvardage pour l’évaluation des protéines de choc thermique HSP70 et HSP32. Les rats BDL ont une diminution de leur mémoire à court terme comparativement aux contrôles, et sont aussi plus anxieux. En comprenant mieux les mécanismes associés à l’hypotension, il sera possible de trouver de nouvelles avenues thérapeutiques pour le traitement de l’EH et les complications neurologiques associées à la transplantation du foie.

Aims: The pathogenesis of hepatic encephalopathy (HE) is multifactorial. Even though ammonia is the central component in the pathogenesis of HE, oxidative stress is believed to play a role in exacerbating the neuropsychological effects of ammonia in patients with liver disease. With new, highly sensitive imaging techniques, brain edema is observed in HE patients. We previously demonstrated that portacaval shunted hyperammonemic rats do not develop oxidative stress or brain edema. In order to define a synergistic effect between hyperammonemia and systemic oxidative stress, the present study investigates the role of oxidative stress in the pathogenesis of brain edema in PCA rats following glutathione depletion by diethyl maleate (DEM). Methods: In the first set of experiments, we evaluated the effect of DEM in PCA and SHAM-operated control rats by injecting DEM at a dose of 0.4 and 1 mg/kg/day intraperitoneally for 10 days starting at day 18 after surgery. Rats were sacrificed at day 28 and oxidative stress was evaluated by arterial malon-dialdehyde (MDA, commercial kit). In the second set of experiments, 1 mg/kg/day DEM was used to induce oxidative stress. Ammonia (commercial kit) as well as other different oxidative stress markers: reactive oxygen species (DCFDA fluorescence technique), and 4-hydroxy-2-nonenal (HNE, Western blot) were assessed in arterial plasma and frontal cortex tissue. Brain water content was measured in the frontal cortex using a specific gravimetric technique. Results: DEM at 1 mg/kg/day (not 0.4 mg/kg/day) induced a significant increase in MDA levels in PCA rats. No increase in MDA was detected following either dose of DEM in SHAM-operated controls. Ammonia levels in both DEM-treated and non-treated PCA rats were significantly increased vs respective sham-operated controls (p<0.001) and remained unchanged between non-treated and DEM-treated PCA groups (p>0.05). An increase in brain water content was observed in DEM-treated PCA rats vs non-treated PCA rats (PCA+DEM: 78.45 ± 0.13% vs PCA: 77.38 ± 0.11, p< 0.001). Although no significant changes in reactive oxygen species were observed, there was an increase in plasma levels of HNE in DEM-treated PCA rats compared to non-treated PCA rats. No significant changes in any oxidative stress markers were observed in the frontal cortex. Conclusions: DEM treatment in PCA rats induced systemic oxidative stress but not central oxidative stress. This, imposed on hyperammonemia, was accompanied by the onset of brain edema in rats with PCA. Oxidative stress and brain edema were not detected in SHAM-operated rats, which were not hyperammonemic. Our findings suggest a synergistic effect between hyperammonemia and systemic oxidative stress is implicated in the pathogenesis of brain edema in hepatic encephalopathy.

Aims: The pathogenesis of hepatic encephalopathy (HE) is multifactorial. Even though ammonia is the central component in the pathogenesis of HE, oxidative stress is believed to play a role in exacerbating the neuropsychological effects of ammonia in patients with liver disease. With new, highly sensitive imaging techniques, brain edema is observed in HE patients. We previously demonstrated that portacaval shunted hyperammonemic rats do not develop oxidative stress or brain edema. In order to define a synergistic effect between hyperammonemia and systemic oxidative stress, the present study investigates the role of oxidative stress in the pathogenesis of brain edema in PCA rats following glutathione depletion by diethyl maleate (DEM). Methods: In the first set of experiments, we evaluated the effect of DEM in PCA and SHAM-operated control rats by injecting DEM at a dose of 0.4 and 1 mg/kg/day intraperitoneally for 10 days starting at day 18 after surgery. Rats were sacrificed at day 28 and oxidative stress was evaluated by arterial malon-dialdehyde (MDA, commercial kit). In the second set of experiments, 1 mg/kg/day DEM was used to induce oxidative stress. Ammonia (commercial kit) as well as other different oxidative stress markers: reactive oxygen species (DCFDA fluorescence technique), and 4-hydroxy-2-nonenal (HNE, Western blot) were assessed in arterial plasma and frontal cortex tissue. Brain water content was measured in the frontal cortex using a specific gravimetric technique. Results: DEM at 1 mg/kg/day (not 0.4 mg/kg/day) induced a significant increase in MDA levels in PCA rats. No increase in MDA was detected following either dose of DEM in SHAM-operated controls. Ammonia levels in both DEM-treated and non-treated PCA rats were significantly increased vs respective sham-operated controls (p<0.001) and remained unchanged between non-treated and DEM-treated PCA groups (p>0.05). An increase in brain water content was observed in DEM-treated PCA rats vs non-treated PCA rats (PCA+DEM: 78.45 ± 0.13% vs PCA: 77.38 ± 0.11, p< 0.001). Although no significant changes in reactive oxygen species were observed, there was an increase in plasma levels of HNE in DEM-treated PCA rats compared to non-treated PCA rats. No significant changes in any oxidative stress markers were observed in the frontal cortex. Conclusions: DEM treatment in PCA rats induced systemic oxidative stress but not central oxidative stress. This, imposed on hyperammonemia, was accompanied by the onset of brain edema in rats with PCA. Oxidative stress and brain edema were not detected in SHAM-operated rats, which were not hyperammonemic. Our findings suggest a synergistic effect between hyperammonemia and systemic oxidative stress is implicated in the pathogenesis of brain edema in hepatic encephalopathy.

Background: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (CLD). Malnutrition, considered a consequence of metabolic disturbances (hypermetabolism), exacerbates sarcopenia (severe muscle loss) and hepatic encephalopathy (complex neuropsychiatric disorder) in cirrhotic patients. New management strategies focussing on improving nutritional status and attenuating CLD-related complications are an unmet clinical need. We hypothesize supplementation with branched-chain amino acid isoleucine (ILE) and exercise could possibly attenuate muscle mass loss and prevent brain edema, a common entity of hepatic encephalopathy, in CLD. Methods: CLD was induced in rats following 6-week bile-duct ligation (BDL). Five experimental groups were tested; 1) BDL; 2) BDL + ILE; 3) BDL + EX; 4) BDL + ILE + EX; 5) Sham-operated rats. Two weeks following BDL, rats were submitted to 15 min exercise (10 cm/s) every other day and BDL rats receiving ILE, were gavaged daily (1.5 mg/kg) for 4 weeks. Body weight, muscle (gastrocnemius) mass, metabolic state (calculation of energy expenditure independent of food intake and fecal mass) and cerebral edema (specific gravity method) were measured in all groups. Results: BDL rats gained less body weight (33.7  6.3 g vs 204.5  26.0 g; p < 0.01) and muscle mass (weight/body weight ratio) (0.0047  0.0002 vs 0.0051  0.0002; p < 0.05) compared to sham-operated rats, respectively. ILE-treated BDL rats submitted to exercise demonstrated an increase in weight gain and an increase in muscle mass (weight/body weight ratio) (0.0056  0.0003 vs 0.0047  0.0003; p < 0.05) and an attenuation in hypermetabolic status, compared to BDL rats respectively. ILE+exercsie also attenuated brain water content in BDL rats. Conclusion: Our results demonstrate that supplemental ILE along with exercise reduces body weight and muscle mass loss, improves metabolic activity and attenuates brain edema. These findings suggest that strategies aiming at improving nutritional status and preventing muscle mass loss will attenuate the onset of sarcopenia and hepatic encephalopathy, and therefore improve outcome in CLD. EX and ILE supplementation could rapidly be translated into clinical practice.

Background: Chronic liver disease leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy (HE). Neurotoxic effects of ammonia are known to induce numerous metabolic alterations such as increased brain glutamine and lactate. However, their roles in the development of brain edema are not defined. Aims: Having previously demonstrated an increase in both glutamine and lactate in six-week bile-duct ligated rats (BDL) in association with HE, our aim in the present study was to define the role of lactate in the pathogenesis of brain edema by inhibiting brain lactate production. Methods: BDL rats were treated with dichloroacetate (DCA, 25 mg/kg intraperitoneally, for 7 days starting at week 5 after bile-duct ligation). DCA, a pyruvate dehydrogenase kinase inhibitor leads to pyruvate dehydrogenase stimulation, therefore favoring the oxidation of pyruvate and consequently leading to a decrease in lactate production. Rats were sacrificed at week 6 after bile-duct ligation. In all experimental groups, brain edema was assessed using the specific gravimetric technique, lactate was measured following its oxidation by lactate oxidase to pyruvate and hydrogen peroxide which reacts with AmplexRed (10-acetyl-3,7-dihidroxyphenoxazine) generating measurable resorufin (fluorescent product) and glutamine was quantified using high performance liquid chromatography. Results: Six weeks following BDL, rats develop brain edema, as well as increased brain lactate and glutamine compared to SHAM-operated controls. DCA treatment normalized brain lactate in BDL rats (76.17±3.31 µM/100 µg protein vs BDL: 254.60±10.12 µM/100 µg protein, p<0.001; non-significant vs SHAM: 111.70±7.08 µM/100 µg protein). DCA-treated BDL rats demonstrated a significant reduction of brain water content reaching values similar to those seen in SHAM-operated rats (77.49±0.07% vs BDL: 78.46±0.28%; p<0.05; non-significant vs SHAM: 77.35±0.17%). Glutamine levels were increased in BDL vs sham operated rats and remained high in DCA-treated BDL rats (569.20±80.44 µM vs BDL: 796.60±71.50 µM; p<0.001; both increased vs SHAM: 442.80±33.79 µM; p<0.01). Conclusions: Inhibition of lactate synthesis led to an attenuation in brain edema and brain lactate levels while brain glutamine levels remained elevated. Our findings suggest increased brain lactate, not glutamine, is an important factor in the pathogenesis of brain edema. DCA has previously demonstrated a long-term safety profile in patients with congenital lactic acidosis and beneficial effects with no adverse reactions in other diseases such as cancer and chronic obstructive pulmonary disease. Therefore, inhibition of lactate synthesis can rapidly provide a promising therapeutic approach for the management of patients with end-stage liver disease.

The pathogenesis of brain edema in patients with chronic liver disease (CLD) and minimal hepatic encephalopathy (HE) remains undefined. This study evaluated the role of brain lactate, glutamine and organic osmolytes, including myo-inositol and taurine, in the development of brain edema in a rat model of cirrhosis.Six-week bile-duct ligated (BDL) rats were injected with (13)C-glucose and de novo synthesis of lactate, and glutamine in the brain was quantified using (13)C nuclear magnetic resonance spectroscopy (NMR). Total brain lactate, glutamine, and osmolytes were measured using (1)H NMR or high performance liquid chromatography. To further define the interplay between lactate, glutamine and brain edema, BDL rats were treated with AST-120 (engineered activated carbon microspheres) and dichloroacetate (DCA: lactate synthesis inhibitor).Significant increases in de novo synthesis of lactate (1.6-fold, p<0.001) and glutamine (2.2-fold, p<0.01) were demonstrated in the brains of BDL rats vs. SHAM-operated controls. Moreover, a decrease in cerebral myo-inositol (p<0.001), with no change in taurine, was found in the presence of brain edema in BDL rats vs. controls. BDL rats treated with either AST-120 or DCA showed attenuation in brain edema and brain lactate. These two treatments did not lead to similar reductions in brain glutamine.Increased brain lactate, and not glutamine, is a primary player in the pathogenesis of brain edema in CLD. In addition, alterations in the osmoregulatory response may also be contributing factors. Our results suggest that inhibiting lactate synthesis is a new potential target for the treatment of HE.

The pathogenesis of hepatic encephalopathy (HE) is multifactorial and often associated with the development of brain oedema. In addition to ammonia playing a central role, systemic oxidative stress is believed to aggravate the neuropsychological effects of ammonia in patients with chronic liver disease (CLD). The aim of this study was to (i) induce systemic oxidative stress in hyperammonaemic portacaval anastomosed (PCA) rats by inhibiting the antioxidant glutathione using Dimethyl maleate (DEM) and (ii) investigate whether a synergistic relationship between ammonia and oxidative stress contributes to the pathogenesis of brain oedema in CLD.Four-week PCA and sham-operated rats received DEM (0.4-4 mg/kg/day) for the last 10 days before sacrifice when oxidative stress markers [reactive oxygen species (ROS) and malondialdehyde (MDA)] were assessed in blood and frontal cortex. Brain water content was measured using a specific gravimetric technique.Dimethyl maleate induced an increase in ROS and MDA in the blood, but not in the brain, of the PCA rats, compared with non-treated PCA rats. This was accompanied with an increase in brain water content (PCA+DEM: 78.45 ± 0.13% vs. PCA: 77.38 ± 0.11 P < 0.001). Higher doses of DEM induced systemic oxidative stress in sham-operated controls, but brain oedema did not develop.Dimethyl maleate provoked systemic, not central, oxidative stress in PCA rats, resulting in the development of brain oedema. Independently, hyperammonaemia and systemic oxidative stress do not precipitate brain oedema; therefore, our findings sustain that a synergistic effect between hyperammonaemia and systemic oxidative stress is responsible for the development of brain oedema in HE.

Introduction: La malnutrition est un important facteur de pronostique qui peut affecter le résultat clinique des patients souffrant d’une maladie hépatique chronique (MHC). Étant une cause du hypermétabolisme, la malnutrition aggrave l’encéphalopathie hépatique et la sarcopénie chez les patients cirrhotiques. Des nouvelles stratégies de traitement visant l’amélioration de l’état nutritionnel et l’atténuation des complications de la MHC sont un besoin clinique à satisfaire. Notre hypothèse était que la supplémentation avec l’acide aminé ramifié isoleucine (ILE) et l’exercice physique (EX) peuvent atténuer la perte de masse musculaire et prévenir l’œdème cérébral dans la MHC. Méthodes : MHC a été induite chez des rats suite à une ligature de la voie biliaire (LVB). 5 groupes expérimentaux ont été étudiés : 1) LVB; 2) LVB + ILE; 3) LVB + EX; 4) LVB + ILE + EX; 5) SHAM opérés. Deux semaines après la LVB, les rats LVB + EX ont subi des sessions d’exercice de 15 min (10 cm/s) à chaque 2 jours et les rats ILE ont été gavés à chaque jour (1.5 mg/kg ILE) pendant 4 semaines. Le poids, la masse musculaire (muscle gastrocnémien), l’état métabolique (la dépense énergétique indépendante de la quantité de nourriture et masse fécale) et l’œdème cérébral (gravimétrie spécifique) ont été mesurés. Résultats : LVB + EX + ILE ont démontré un gain du poids corporel significatif (LVB + ILE + EX: 112.3 g vs LVB: 33.7 g; p < 0.05), une augmentation de la masse musculaire (poids muscle/poids corporel) (LVB + ILE + EX: 0.0056 vs LVB: 0.0047; p < 0.05) et une atténuation de l’état hypermétabolique. Le contenu en eau cérébrale a diminué chez les rats LVB+ ILE + EX comparé aux rats LVB. Conclusion: Nos résultats démontrent que l’EX et l’ILE améliorent le poids corporel, la masse musculaire, le métabolisme et atténuent l’œdème cérébral. Cela suggère que des stratégies visant l’optimisation de la masse musculaire et l’amélioration de l’état nutritionnel pourraient diminuer les complications chez des patients cirrhotiques.

Background: Acute-on-chronic liver failure (ACLF) is defined as an acute decompensation of chronic liver disease. Brain edema is frequently observed in hepatic encephalopathy associated with both acute and chronic liver disease. While in acute liver failure, toxic levels of ammonia induce cerebral oxidative stress and brain edema, in chronic liver disease, systemic (not central) oxidative stress and hyperammonemia synergistically cause brain edema. This study investigated the role of both systemic and central oxidative stress and ammonia in relation to brain edema in a rat model of ACLF. Methods: ACLF was induced in male Sprague-Dawley rats by portacaval shunt (PCA), followed 4 weeks later by hepatic artery ligation (HAL). Acute liver failure (ALF) induced by concomitant PCA and HAL, PCA (4 weeks) and SHAM-operated rats were used as controls. ACLF rats were divided into 2 groups that were sacrificed at: 1) coma stage of hepatic encephalopathy (defined as loss of corneal reflex) (ACLF-C) and 2) in parallel with ALF-induced coma (ACLF-P) rats. Brain edema (specific gravimetric technique), ammonia levels (commercial kit) and oxidative stress markers (plasmatic and cerebral reactive oxygen species, fluorescence spectroscopy) were evaluated along with hepatic function (routine biochemistry, haematoxylin-phloxine-saffron histopathology). Results: Coma was delayed by 8h in ACLF compared to ALF rats (p< 0.01). Liver biochemistry markers did not differ between ACLF-C, ACLF-P and ALF rats; liver histopathology showed mild necrosis in ACLF-P, moderate in ALF and severe in ACLF-C. Brain water content was significantly attenuated in both ACLF-C and ACLF-P vs. ALF rats (p< 0.01). Arterial ammonia concentration followed a similar pattern: they were attenuated in ACLF-C: 0.35±0.07 mM and ACLF-P: 0.49±0.14 mM vs. ALF: 1.34±0.09 mM (p< 0.001), but remained high compared to SHAM: 0.06±0.01 mM (p< 0.001). Systemic oxidative stress was present in both ACLF and ALF rats, while cerebral oxidative stress was present only in ALF rats. Conclusion: Brain edema, ammonia levels and oxidative stress are reduced in ACLF rats compared to ALF rats. These findings suggest that during chronic liver failure, compensatory mechanisms that prevent the apparition of brain edema and attenuate oxidative stress during an acute deterioration are developed.

Background: Malnutrition is an important prognostic factor which can influence clinical outcome of patients suffering from chronic liver disease (CLD). Believed to cause hypermetabolism, malnutrition exacerbates hepatic encephalopathy and sarcopenia in cirrhotic patients. New management strategies focussing on improving nutritional status and attenuating CLD complications are an unmet clinical need. We hypothesize supplementation with branched-chain amino acid isoleucine (ILE) and exercise (EX) could possibly attenuate muscle mass loss and prevent brain edema in CLD. Methods: CLD was induced in rats following 6-week bile-duct ligation (BDL). Five experimental groups were tested; 1) BDL; 2) BDL + ILE; 3) BDL + EX; 4) BDL + ILE + EX; 5) Sham-operated rats. Two weeks post BDL, BDL + EX rats were submitted to 15 min exercise (10 cm/s) every other day and BDL rats receiving ILE, were gavaged daily (1.5 mg/kg) for 4 weeks. Body weight, muscle (gastrocnemius) mass, metabolic state (calculation of energy expenditure independent of food intake and fecal mass) and cerebral edema (specific gravity method) were measured in all groups. Results: BDL + EX + ILE demonstrated a significant gain in body weight (BDL + ILE + EX: 112.3 g vs BDL: 33.7 g; p < 0.05), an increase in muscle mass (weight/body weight ratio) (BDL + ILE + EX: 0.0056 vs BDL: 0.0047; p < 0.05) and attenuated hypermetabolic status. Brain water content was decreased in BDL + ILE + EX rats compared to BDL animals. Conclusion: Our results demonstrate that EX and supplemental ILE improve body weight, muscle mass, metabolic activity and attenuate cerebral edema. These findings suggest that strategies aiming at muscle mass optimization and improving nutritional status attenuate complications and therefore improve outcome in patients with CLD. EX and ILE supplementation could rapidly be translated into clinical practice.

Background: Liver failure/disease leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy. There is increasing evidence that oxidative stress exacerbates the neuropsychological effects of hyperammonemia in patients with liver disease, possibly by inducing brain edema. The latter represents a common entity in cirrhotic patients with hepatic encephalopathy. Since rats following 4-week portacaval anastomosis (PCA) become hyperammonemic but do not develop oxidative stress or brain edema, we aimed to investigate the impact of oxidative stress on the development of brain edema in this rat model. Methods: Oxidative stress was induced following glutathione (GSH) depletion by diethyl maleate (DEM). PCA and SHAM-operated rats received DEM (1 mg/kg/day intraperitoneally) for 10 days starting at day 18 after surgery. Rats were sacrificed at day 28 and oxidative stress markers, such as glutathione (GSH), malon-dialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE) were assessed in arterial plasma and brain (frontal cortex) tissue. Plasma ammonia and liver function markers (AST, ALT, bilirubin) were also evaluated. Brain water content was measured using a specific gravimetric technique. Results: DEM induced a significant decrease in plasmatic GSH, which lead to an increase in arterial MDA (2.5 fold) and HNE (1.4 fold) levels in PCA rats compared to non-treated PCA rats. An increase in brain water content was observed in DEM-treated PCA rats vs non-treated PCA rats (PCA+DEM: 78.45 ± 0.13% vs PCA: 77.38 ± 0.11%, p< 0.001). In the brain, oxidative stress markers measured in the frontal cortex did not differ between the two groups. DEM treatment did not affect the degree of hyperammonemia or lead to an alteration in liver function in comparison to non-treated PCA rats. Conclusions: DEM induced systemic, not central, oxidative stress in PCA rats. This, imposed on hyperammonemia, resulted in an increase in brain water content. Since oxidative stress and brain edema were not detected in non-treated hyperammonemic PCA rats, together our findings suggest that a synergistic effect between hyperammonemia and systemic oxidative stress is implicated in the pathogenesis of brain edema in hepatic encephalopathy.

Background: Acute-on-chronic liver failure (ACLF) is defined as an acute decompensation of chronic liver disease. Brain edema is frequently observed in hepatic encephalopathy associated with both acute and chronic liver disease. While in acute liver failure, toxic levels of ammonia induce cerebral oxidative stress and brain edema, in chronic liver disease, systemic (not central) oxidative stress and hyperammonemia synergistically cause brain edema. This study investigated the role of both systemic and central oxidative stress and ammonia in relation to brain edema in a rat model of ACLF. Methods: ACLF was induced in male Sprague-Dawley rats by portacaval shunt (PCA), followed 4 weeks later by hepatic artery ligation (HAL). Acute liver failure (ALF) induced by concomitant PCA and HAL, PCA (4 weeks) and SHAM-operated rats were used as controls. ACLF rats were divided into 2 groups that were sacrificed at: 1) coma stage of hepatic encephalopathy (defined as loss of corneal reflex) (ACLF-C) and 2) in parallel with ALF-induced coma (ACLF-P) rats. Brain edema (specific gravimetric technique), ammonia levels (commercial kit) and oxidative stress markers (plasmatic and cerebral reactive oxygen species, fluorescence spectroscopy) were evaluated along with hepatic function (routine biochemistry, haematoxylin-phloxine-saffron histopathology). Results: Coma was delayed by 8h in ACLF compared to ALF rats (p< 0.01). Liver biochemistry markers did not differ between ACLF-C, ACLF-P and ALF rats; liver histopathology showed mild necrosis in ACLF-P, moderate in ALF and severe in ACLF-C. Brain water content was significantly attenuated in both ACLF-C and ACLF-P vs. ALF rats (p< 0.01). Arterial ammonia concentration followed a similar pattern: they were attenuated in ACLF-C: 0.35±0.07 mM and ACLF-P: 0.49±0.14 mM vs. ALF: 1.34±0.09 mM (p< 0.001), but remained high compared to SHAM: 0.06±0.01 mM (p< 0.001). Systemic oxidative stress was present in both ACLF and ALF rats, while cerebral oxidative stress was present only in ALF rats. Conclusion: Brain edema, ammonia levels and oxidative stress are reduced in ACLF rats compared to ALF rats. These findings suggest that during chronic liver failure, compensatory mechanisms that prevent the apparition of brain edema and attenuate oxidative stress during an acute deterioration are developed.

Aims: Acute-on-chronic liver failure (ACLF), an acute deterioration of liver function during compensated chronic liver disease, is associated with the development of hepatic encephalopathy (HE). Brain edema is frequently observed in patients with HE induced by either acute liver failure (ALF) or chronic liver disease. We recently demonstrated in a rat model of cirrhosis that hyperammonemia and systemic oxidative stress synergistically lead to brain edema. Therefore, the aim of this study was to develop a rat model of ACLF by inducing an acute liver insult, superimposed onto a chronic hyperammonemia background, and to investigate the role of oxidative stress and ammonia in relation to brain edema. Methods: ACLF was induced in male Sprague-Dawley rats by portacaval shunt (PCA), followed 4 weeks later by hepatic artery ligation (HAL). Liver devascularisation by concomitant PCA and HAL was used to induce ALF. SHAM and PCA (chronic hyperammonemic) rats, sacrificed 4 weeks after surgery, were included as controls. Liver status (routine biochemistry and histopathology), blood ammonia and brain edema (specific gravimetric technique) were assessed. Oxidative stress was evaluated by plasmatic and cerebral levels of reactive oxygen species (DCFDA fluorescence), glutathione (DTNB method), and activities of xanthine oxidase and catalase (Amplex Red method). Results : Coma developed in ALF rats 8h after HAL; it was significantly delayed in ACLF rats, where it occurred after 16h. Liver necrosis markers AST and ALT did not differ between pair-killed ACLF and ALF rats; however, liver histopathology showed more severe necrosis in ACLF than in ALF rats. Brain water content increased in ALF rats and was significantly attenuated in ACLF rats: 80.04±0.13% p<0.01vs ALF (81.39±0.15%), n.s. vs SHAM. The increase in arterial ammonia, as seen in ALF rats, was prevented in ACLF rats: 0.35±0.07 mM, p<0.001vs ALF (1.34±0.09 mM), p<0.01 vs SHAM. Oxidative stress was present in the blood of both ACLF and ALF rats, while signs of oxidative stress in the brain were present only in the ALF rats. Conclusions: The alterations observed in ALF are attenuated in ACLF. In spite of a more severe hepatic necrosis in the ACLF rats, the onset of coma was delayed, and brain edema, ammonia levels and oxidative stress were reduced in comparison to the ALF rats. In conclusion, severe HE is alleviated by compensatory mechanisms comprising oxidative stress, which are developed during chronic hyperammonemia prior to an acute liver deterioration. A better understanding of these mechanisms may help define the pathogenesis of ACLF.

Introduction : L’encéphalopathie hépatique (EH) est un syndrome neuropsychiatrique métabolique qui survient comme complication majeure de la cirrhose hépatique. Les causes de l’EH sont multifactorielles, mais les mécanismes précis ont encore besoin d’être élucidés. Le méthylglyoxal (MG) est un sous-produit toxique de la glycolyse et un agent puissant de glycation des molécules cellulaires, et est associé à des maladies affectant le cerveau comme l’encéphalopathie diabétique et la maladie d’Alzheimer. Dans cette étude, nous explorons l’implication du MG dans la physiopathologie de l’EH. Méthodes : La cirrhose a été induite suite à une ligature de voie biliaire (BDL) pendant 6 semaines et une dérivation portosystémique (PCA) a été effectuée pour 4 semaines. Chez ces modèles animaux de l’EH, nous avons dosé des marqueurs du MG, le D-lactate et les produits de glycation avancée (AGEs), par fluorescence et Western Blot, respectivement. L’expression protéique des enzymes glyoxalase 1 (Glo1) et glyoxalase 2 (Glo2) a été effectuée par Western Blot alors que l’activité de Glo1 a été évaluée par cinétique enzymatique en spectrophotométrie UV. Résultats : Aucune différence significative du D-lactate et des AGEs, deux marqueurs du métabolisme du MG, a été détectée dans les modèles animaux de l’EH. De plus, aucune altération de l’expression protéique de Glo1 et Glo2 ainsi que l’activité de Glo1 a été observée dans le système glyoxalase, détoxifiant le MG, dans l’EH. Conclusion : Cette étude, pour la première fois, caractérise la relation entre MG et l’EH et suggère aucune implication de celui-ci dans l’EH. Financement: Bourse d’étude V Tran : COPSE de l’Université de Montréal. L. Bilodeau : American Gastroenterological Association. C. Bosoi : FRQS

Introduction: Les patients avec une insuffisance hépatique chronique souffrent fréquemment de décompensations aigues de la fonction hépatique (DAH). L’œdème cérébral est une complication de l’insuffisance hépatique aigue ainsi que de celle chronique. Le stress oxydatif et l’ammoniaque contribuent à l’induction de l’œdème cérébral lors d’une insuffisance hépatique chronique. Le but de cette étude est d’investiguer le rôle du stress oxydatif et de l’hyperammoniémie en relation avec l’œdème cérébral dans un modèle de DHA chez le rat. Méthodes: DHA a été induite chez des rats suite à une anastomose portocave (APC) suivie par la ligature de l’artère hépatique (LAH), 4 semaines plus tard. L’insuffisance hépatique aigue (IHA) a été induite par une APC et une HAL effectuées simultanément. Des rats contrôles SHAM et APC ont été sacrifiés 4 semaines après la chirurgie. L’œdème cérébral (gravimétrie spécifique), les espèces réactives d’oxygène et le glutathion (spectrophotométrie) ont été mesurés dans le plasma et dans le cerveau. Résultats: Le début du coma a été significativement retardé chez les rats DHA comparé aux rats IHA. L’examen histopathologique du foie a démontré une nécrose plus sévère chez les rats DHA que chez les rats IHA. Pourtant l’œdème cérébral et l’augmentation de l’ammoniaque ont été prévenus chez ces rats : eau cérébrale 80.04±0.13 % (p<0.01 vs IHA) et ammoniaque plasmatique 0.35±0.07 mM (p<0.001 vs IHA). Chez les rats DHA, le stress oxydatif a été seulement détecté systémiquement tandis que chez les rats IHA, il était présent tant au niveau systémique que cérébral. Conclusions: Les altérations observées dans l’insuffisance hépatique aigue sont améliorées lors d’une DHA survenant sur une hyperammoniémie chronique: l’œdème cérébral, l’ammoniaque et le stress oxydatif sont réduits et le coma est retardé. Cela suggère que des mécanismes compensatoires développés durant une hyperammoniémie chronique préviennent les manifestations sévères d’une insulte hépatique aigue

Introduction : L’encéphalopathie hépatique (EH) est un syndrome neuropsychiatrique métabolique qui survient comme complication majeure de la cirrhose hépatique. Les causes de l’EH sont multifactorielles, mais les mécanismes précis ont encore besoin d’être élucidés. Le méthylglyoxal (MG) est un sous-produit toxique de la glycolyse et un agent puissant de glycation des molécules cellulaires, et est associé à des maladies affectant le cerveau comme l’encéphalopathie diabétique et la maladie d’Alzheimer. Dans cette étude, nous explorons l’implication du MG dans la physiopathologie de l’EH. Méthodes : La cirrhose a été induite suite à une ligature de voie biliaire (BDL) pendant 6 semaines et une dérivation portosystémique (PCA) a été effectuée pour 4 semaines. Chez ces modèles animaux de l’EH, nous avons dosé des marqueurs du MG, le D-lactate et les produits de glycation avancée (AGEs), par fluorescence et Western Blot, respectivement. L’expression protéique des enzymes glyoxalase 1 (Glo1) et glyoxalase 2 (Glo2) a été effectuée par Western Blot alors que l’activité de Glo1 a été évaluée par cinétique enzymatique en spectrophotométrie UV. Résultats : Aucune différence significative du D-lactate et des AGEs, deux marqueurs du métabolisme du MG, a été détectée dans les modèles animaux de l’EH. De plus, aucune altération de l’expression protéique de Glo1 et Glo2 ainsi que l’activité de Glo1 a été observée dans le système glyoxalase, détoxifiant le MG, dans l’EH. Conclusion : Cette étude, pour la première fois, caractérise la relation entre MG et l’EH et suggère aucune implication de celui-ci dans l’EH. Financement: Bourse d’étude V Tran : COPSE de l’Université de Montréal. L. Bilodeau : American Gastroenterological Association. C. Bosoi : FRQS

Background: Acute-on-chronic liver failure (ACLF) represents an acute decompensation of chronic liver disease. Brain edema is frequently observed in hepatic encephalopathy associated with both acute and chronic liver disease. Since systemic oxidative stress and ammonia are believed to act synergistically in inducing brain edema in chronic liver failure, the objective of this study was to develop a rat model of hepatic encephalopathy following ACLF, and to investigate the role of oxidative stress and ammonia in relation to brain edema. Methods: ACLF was induced in male Sprague-Dawley rats by portacaval shunt (PCA), followed 4 weeks later by hepatic artery ligation (HAL). Liver devascularisation by concomitant PCA and HAL was used to induce acute liver failure (ALF). Body temperature and blood glucose were monitored and maintained throughout the progression to coma. Control SHAM and PCA rats, sacrificed 4 weeks after surgery, were also included. Routine biochemistry and liver histopathology were used to assess liver status. Brain edema (specific gravimetric technique), reactive oxygen species and glutathione levels (spectrophotometry) were measured in plasma and brain tissue of all groups. Results: The onset of coma was significantly delayed in ACLF compared to ALF rats by approximately 8h. Liver necrosis markers AST and ALT did not differ between ACLF and ALF rats; however, liver histopathology showed more severe necrosis in ACLF than in ALF rats. Brain water content was significantly attenuated in acute-on-chronic rats: ACLF: 80.04±0.13 % (ns vs SHAM; p<0.01 vs ALF); SHAM: 80.12±0.09 %; ALF: 81.39±0.15 % (p<0.01 vs SHAM). Increase in arterial ammonia concentration was prevented in ACLF rats: ACLF: 0.35±0.07 mM (p<0.001 vs SHAM; p<0.001 vs ALF); SHAM: 0.06±0.01 mM; ALF: 1.34±0.09 mM (p<0.001 vs SHAM). Evidence of oxidative stress (increased reactive oxygen species and decreased glutathione levels) was systemically present in both ACLF and ALF rats, while signs of oxidative stress in the brain were present only in ALF rats. Conclusions: Our animal model of acute liver insult, superimposed on chronic hyperammonemia, reproduces the alterations observed in acute liver failure; however, the latter were attenuated. In spite of a more severe liver necrosis in ACLF rats, the onset of coma was delayed, and brain edema, ammonia levels and oxidative stress were reduced when compared to ALF rats. These findings therefore suggest that during chronic liver failure, compensatory mechanisms are developed, which in turn prevent the apparition of brain edema and attenuate oxidative stress during acute deterioration.

Background: Chronic liver failure leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy (HE). Neurotoxic effects of ammonia induce numerous metabolic alterations, such as increased cerebral lactate and glutamine. In brain edema associated with acute liver failure, glutamine plays a controversial and lactate a well-defined role. Brain edema is also present in chronic liver failure; however, roles of lactate and glutamine are less understood. We previously demonstrated an increase in de novo synthesis of lactate in bile-duct ligated rats (BDL). To define the role of lactate in the pathogenesis of brain edema, this study investigates its relationship with ammonia and the effects of inhibiting lactate production. Methods: BDL rats were treated either with AST-120 (spherical carbon adsorbent, 1 g/kg/day for 6 weeks, by gavage) or with dichloroacetate (DCA, 25 mg/kg for 7 days starting at week 5 after intervention, intraperitoneally). AST-120 acts as an ammonia sink in the gut. DCA is a pyruvate dehydrogenase kinase inhibitor that leads to pyruvate dehydrogenase stimulation and to a shift of pyruvate metabolism from glycolysis to oxidation and, consequently, to a decrease in lactate production. Brain lactate (Amplex red fluorescence) and glutamine (HPLC), as well as edema (specific gravimetric technique) were measured in brain tissue of non-treated and treated BDL rats. Results: Brain lactate and glutamine increased and brain edema developed in BDL rats vs SHAM-operated controls. AST-120 treatment partially decreased lactate levels: AST-120-treated BDL: 155.1±12.8 µM (p<0.05 vs SHAM, p<0.001 vs BDL) compared to BDL: 254.6±10.1 µM (p<0.001 vs SHAM) and SHAM: 111.7±7.1 µM; while glutamine levels did not change: AST-120-treated BDL: 1024.2.±65.2 µM (p<0.001 vs SHAM, ns vs BDL) compared to BDL: 796.6±71.5 µM (p<0.001 vs SHAM) and SHAM: 442.8±33.8 µM. Following DCA treatment, in treated BDL rats brain lactate normalized (76.2±3.3 µM, ns vs SHAM, p<0.001 vs BDL) and glutamine levels remained unchanged (569.2±80.4 µM, p<0.05 vs SHAM, ns vs BDL). Both AST-120 and DCA treatments led to a significant reduction of brain water content, reaching similar values to those seen in SHAM-operated rats. Conclusions: Ammonia-lowering therapy prevented the apparition of brain edema by partially decreasing brain lactate, thus suggesting that ammonia is not the only factor that contributes to an increase in brain lactate. Inhibition of lactate production attenuated brain edema, while cerebral glutamine remained high. Our findings reveal that increased brain lactate, and not glutamine, contributes to the pathogenesis of brain edema in minimal HE.

L’encéphalopathie hépatique (EH), un syndrome métabolique neuropsychiatrique, est une complication majeure de la maladie hépatique. L'EH est caractérisée par des troubles cognitifs, psychiatriques et moteurs allant jusqu'au coma hépatique et la mort. Les causes de l'EH sont multifactorielles et encore assez peu connues. L’ammoniaque, neurotoxique, est considérée comme le facteur principal. Celle-ci est produite par la dégradation des protéines au niveau intestinal. Elle est détoxiquée par le cycle d'urée dans le foie, une voie métabolique qui permet d’éliminer de l’organisme les excès d’azote d’origine endogène ou exogène. Au cours de l’insuffisance hépatique chronique, le cycle d’urée est déficient et en conséquence une concentration anormalement élevée d’ammoniaque circule dans le sang (hyperammoniémie) et atteint le cerveau. L’ammoniaque peut aussi être produite par désamination de la glutamine en glutamate et en ammoniaque par la glutaminase, une enzyme exprimée dans les hépatocytes périportaux. La glutaminase est également exprimée dans les cellules épithéliales des tubules rénaux, où l'ammoniaque produit est excrétée sous forme d'ions ammonium, un mécanisme important de la fonction rénale de la régulation acide-base. On la retrouve aussi dans le cerveau où elle joue un rôle essentiel dans la production du neurotransmetteur glutamate. L’hypothèse du projet est que la glutaminase joue un rôle fondamental dans le développement de l’hyperammoniémie dans l’insuffisance hépatique chronique. Ce projet a comme objectif principal de mesurer l’activité enzymatique (par dosage enzymatique) et l’expression (par immunobuvardage) de la glutaminase dans le rein, le foie et le cerveau lors d’insuffisance hépatique chronique induite chez le rat. Les résultats de ce travail nous permettront de comprendre le rôle de la glutaminase dans l’hyperammoniémie observée chez les patients atteints d’insuffisance hépatique chronique.

Introduction: L’insuffisance hépatique mène à l’hyperammonémie, le facteur principal de l’encéphalopathie hépatique (EH). Toutefois, le stress oxydatif peut avoir un rôle important dans l’exacerbation des effets neuropsychologiques de l’hyperammonémie chez les patients atteints de maladies hépatiques, dont l’œdème cérébral. Les rats cirrhotiques développent l’hyperammonémie et l’œdème cérébral, mais aussi une augmentation des espèces réactives d’oxygène (ROS) plasmatiques suite à une augmentation de l’activité de la xanthine oxydase. Afin de mieux comprendre la relation entre l’ammoniaque et le stress oxydatif dans la pathogenèse de l’œdème cérébral, dans cette étude nous avons investigué l’effet de l’allopurinol, un inhibiteur de la xanthine oxydase, chez des rats cirrhotiques. Méthodes: La cirrhose a été induite suite à une ligature de voie biliaire (BDL) pendant 6 semaines. Des rats BDL et contrôles SHAM-opérés ont reçu l’allopurinol (100 mg/kg/jour pour les derniers 10 jours). Des groupes contrôles BDL et SHAM-opérés ont reçu de la saline. L’ammoniaque et les ROS ont été mesurés dans le plasma (artériel) par, respectivement, un kit commercial et une technique de fluorescence. Le contenu en eau du cerveau a été mesuré dans le cortex frontal par une technique spécifique gravimétrique. Résultats: Chez les rats BDL traités avec allopurinol, nous avons observé une diminution significative des ROS et de l’ammoniaque systémique vs les rats BDL non-traités, aux valeurs similaires de celles des rats SHAM. Le contenu en eau du cerveau a été normalisé suite au traitement avec allopurinol. Conclusion: Le traitement avec allopurinol diminue les ROS et l’ammoniaque plasmatique et atténue l’œdème cérébral. Cela a démontré que le stress oxydatif joue un rôle dans le métabolisme de l’ammoniaque et dans la pathogenèse de l’œdème cérébral. Nos résultats suggèrent qu’un traitement antioxydant dirigé vers l’inhibition de la production des ROS pourrait être bénéfique dans le traitement de l’EH.

Introduction: L'encéphalopathie hépatique (EH), une complication grave de la maladie du foie, se manifeste par un syndrome métabolique neuropsychiatrique complexe mais ayant toujours été considérée comme réversible. La transplantation hépatique (TH) est le seul traitement efficace pour traiter les patients de maladie hépatique, par contre les complications neurologiques survenant suite à une TH restent un problème persistant. Avec l’EH pré-TH, l'hypotension et une hypoxie cérébrale pendant la période péri-opératoire peuvent affecter les fonctions neurologiques. Ces observations nous ont conduits à l'hypothèse suivante: un patient cirrhotique atteint d’EH est plus à risque de subir des dommages cérébraux suite à une insulte d’hypotension/hypoxie. Méthodes: Pour vérifier cette hypothèse, nous évaluons l’effet d’une hypotension/hypoxie cérébrale chez un rat avec ligature de la voie biliaire (BDL) de 6 semaines (modèle établi de la maladie chronique du foie et de l’EH). Les animaux ont été sacrifiés et leurs cerveaux ont été évalués pour une perte/altération cellulaire par marquage neuronal (au violet de crésyl et par immunohistochimie avec NeuN) ainsi que pour détecter des protéines pro- et anti-apoptotiques (par western blot). Résultats: Jusqu’à maintenant, nous avons démontré qu’une hypotension/hypoxie cérébrale de 90 minutes ne cause pas de perte neuronale ni une augmentation de marqueurs apoptotiques dans le cerveau de rats encéphalopatiques comparativement aux cerveaux de rats normaux. Conclusions: Nous sommes présentement en train d’évaluer les cerveaux de rats ayant subi une hypotension/hypoxie de 30 minutes. À cause de la fragilité d’un cerveau encéphalopatique, nous croyons qu’une hypotension/hypoxie moindre pourrait donner lieu à une plus grande perte/altération cellulaire que dans un cerveau normal. Nous allons par la suite utiliser d’autres techniques telles que le marquage avec fluorojade, un marqueur d’apoptose et TUNEL une méthode pour détecter fragmentation de l'ADN

Aims: Neurotoxic effects of ammonia have been shown to induce numerous metabolic alterations such as increased brain glutamine and lactate. In brain edema associated with acute liver failure, glutamine plays a controversial role and a few studies demonstrated lactate is also involved. Brain edema is also present in patients with chronic liver failure; in this situation roles of lactate and glutamine are less understood. We previously demonstrated an increase in lactate de novo synthesis in bile-duct ligated rats (BDL), a known model of chronic liver failure/minimal hepatic encephalopathy. To define the role of lactate in the pathogenesis of brain edema, the present study investigates the effects of inhibiting lactate production. Methods: BDL rats were treated with dichloroacetate (DCA, 25 mg/kg for 7 days starting at week 5 after intervention, intraperitoneally), a pyruvate dehydrogenase kinase inhibitor that leads to pyruvate dehydrogenase stimulation, therefore to a shift of pyruvate from glycolysis to oxidation and consequently to a decrease in lactate production. Brain edema (specific gravimetric technique) and glutamine (HPLC) were measured in brain tissue of BDL rats vs sham operated controls. Results: 6 weeks following BDL, rats develop brain edema and increased brain lactate compared to SHAM-operated controls. DCA treatment normalized brain lactate in BDL rats. DCA-treated BDL rats demonstrated a significant reduction of brain water content reaching values similar to those seen in SHAM-operated rats. Glutamine levels were increased in BDL vs sham operated rats and remained high in DCA-treated BDL rats (569.20±80.44 µM vs BDL: 796.60±71.50 µM, and vs SHAM: 442.80±33.79 µM). Conclusions: Inhibition of lactate production attenuated brain edema while cerebral glutamine levels remained high. Our findings suggest increased brain lactate, not glutamine, is associated with brain edema. Impaired lactate metabolism contributes to the pathogenesis of brain edema in minimal hepatic encephalopathy.

Aims: Although ammonia is the central component in the pathogenesis of hepatic encephalopathy, it is believed oxidative stress (OS) plays a role in the pathogenesis of brain edema during liver disease. We previously demonstrated that portacaval shunted hyperammonemic rats do not develop OS or brain edema (Bosoi et al., FRBM, 2012). To define whether a synergistic effect exists between hyperammonemia and OS in the development of brain edema, the present study investigates the role of OS in the pathogenesis of brain edema in PCA rats following glutathione depletion by diethyl maleate (DEM). Methods: We evaluated the effect of DEM (1 mg/kg/day intraperitoneally for 10 days starting day 18 after surgery) in PCA and SHAM-operated rats. Rats were sacrificed at day 28 and OS was evaluated by measuring arterial and cerebral malon-dialdehyde (MDA, commercial kit), reactive oxygen species (ROS, DCFDA fluorescence), and 4-hydroxy-2-nonenal (HNE, Western blot). Ammonia levels (commercial kit) were also assessed. Frontal cortex brain water was measured using a specific gravimetric technique. Results: DEM induced a significant increase in plasma MDA, ROS and HNE levels in PCA rats. No increase was detected in DEM-treated SHAM-operated controls. No changes in cerebral OS markers were observed in any group. Ammonia levels increased in non-treated and DEM-treated PCA vs SHAM-operated rats (p<0.001) and remained unchanged between non-treated and DEM-treated PCA groups. Brain water content increased in DEM-treated PCA rats vs non-treated PCA rats (PCA+DEM: 78.45±0.13% vs PCA: 77.38±0.11%, p< 0.001). Conclusions: DEM treatment in PCA rats induced systemic, not central OS. This, superimposed on hyperammonemia, led to the development of brain edema. Similar DEM doses did not result in increased OS and brain edema in SHAM-operated rats, suggesting PCA rats are more susceptible to OS. Our findings support a synergistic effect between hyperammonemia and systemic OS in the pathogenesis of brain edema in hepatic encephalopathy.

Aims: Acute-on-chronic liver failure (ACLF) represents an acute decompensation of liver cirrhosis. End-to-side portacaval anastomosis (PCA) followed by hepatic artery ligation (HAL) performed after 4 weeks represents a model of liver decompensation. In this model, the onset of coma is delayed compared to acute liver failure induced by hepatic devascularisation. As oxidative stress plays a role in brain edema in chronic liver failure, the objective of this study was to investigate the role of oxidative stress in the pathogenesis of brain edema in ACLF. Methods: Male Sprague-Dawley rats were subjected to PCA followed by hepatic artery ligation (HAL) either concomitantly (HAL-0) or 4 weeks (HAL-4W) following shunt surgery or to a SHAM intervention. Body temperature and blood glucose were monitored and maintained throughout the experiments. Brain edema (specific gravimetric technique) and glutathione levels (spectrophotometry) were measured in brain tissue of all groups. Results: Brain water content was significantly attenuated in “acute-on-chronic” rats (SHAM: 80.12±0.09 %; HAL-0: 81.39±0.15 % (p<0.01 vs SHAM); HAL-4W: 80.04±0.13 % (ns vs SHAM; p<0.01 vs HAL-0)). Arterial ammonia concentration followed a similar pattern (control: 0.060±0.007 mM; HAL-0: 1.340±0.090 mM (p<0.001 vs SHAM); HAL-4W: 0.350±0.070 mM (p<0.001 vs SHAM; p<0.001 vs HAL-0)). Glutathione levels did not change in HAL-4W compared to SHAM and were significantly decreased in the brains of HAL-0 rats (by 36% vs SHAM, p<0.05 and by 25% vs HAL-4W). These effects were not due to an improvement in liver function, as liver necrosis markers AST and ALT did not differ between HAL-4W and HAL-0 rats. Conclusions: Brain edema, ammonia levels and oxidative stress are reduced in ACLF rats compared to acute liver failure rats. These findings suggest that during chronic liver failure compensatory mechanisms are developed that prevent the apparition of brain edema and attenuate oxidative stress during an acute deterioration.

L'encéphalopathie hépatique (EH), un syndrome métabolique neuropsychiatrique, est une complication majeure de la maladie hépatique. L’hyperammonémie est le facteur central dans l’EH. L’œdème cérébral est une importante caractéristique pathophysiologique de l’EH. Nous avons investigué le rôle du stress oxydatif dans deux modèles de maladie du foie/EH chez le rat; 1) dérivation portosystémique (PCA), et 2) ligature de la voie biliaire (BDL). L’ammoniaque et les espèces réactives d’oxygène (ROS) ont été mesurés dans le plasma (artériel) et au niveau cérébral. Le contenu cérébral en eau a été mesuré dans le cortex frontal. L’hyperammonémie s’est développée dans les deux groupes, PCA et BDL (p<0.001 vs contrôles). En conséquence, l’ammoniaque cérébrale était aussi élevée, sans différence significative entre les PCA et BDL. Seuls les rats BDL montraient une augmentation des ROS plasmatiques. Nous n’avons pas observé d’augmentation des ROS cérébraux chez les PCA et BDL. Le contenu en eau du cerveau était augmenté seulement chez les rats BDL (p<0.05 vs contrôles) ; il a été normalisé suite à un traitement avec un antioxydant (allopurinol). L’induction du stress oxydatif chez les rats PCA à l’aide du diméthyle maléate (inhibiteur de glutathion) a provoqué l’augmentation de l’eau cérébrale (p<0.05 vs contrôles). En conclusion, le stress oxydatif systémique est impliqué dans l’œdème cérébral et son effet synergique avec l’ammoniaque contribue à la progression de l’EH.

Aims: Liver disease leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy (HE). There is increasing evidence that systemic oxidative stress may exacerbate the neuropsychological effects of hyperammonemia in patients with liver disease. With new, highly sensitive imaging techniques, brain edema is commonly being observed in patients with cirrhosis and HE. Bile duct ligated rats, six-week after intervention, present with brain edema, hyperammonemia and also an increase in plasma reactive oxygen species (ROS) along with an increase in xanthine oxidase activity. In order to better understand the relationship between oxidative stress and ammonia and their role in the pathogenesis of brain edema, we evaluated the effect of xanthine oxidase inhibition in rats with cirrhosis. Methods: Cirrhosis was induced in rats by bile duct ligation (BDL) for 6 weeks. BDL and SHAM-operated rats received 100 mg/kg/day of allopurinol (xanthine oxidase inhibitor) during the last 10 days before sacrifice. As control groups, separate BDL and SHAM-operated rats received equivalent volume of saline. AST and ALT were measured at the end of the treatment period to assess liver function. Ammonia and ROS were assessed in arterial plasma using a commercially available kit and a DCFDA-fluorescent technique respectively. Brain water content was measured in the frontal cortex using the specific gravimetric technique. Results: Arterial ROS and ammonia levels were significantly increased in BDL vs SHAM-operated rats (p<0.001). BDL rats treated with allopurinol demonstrated a significant decrease in systemic ROS as well as ammonia levels vs non-treated BDL rats (1.70 ± 0.53RFU vs 4.97 ± 1.38RFU, p<0.05, 37.9 ± 13.8µM vs 101.1 ± 10.1µM, p<0.001, respectively), reaching values similar to those seen in SHAM-operated rats. Brain water content increased in BDL vs SHAM-operated rats and normalised in allopurinol treated BDL rats (77.20 ± 0.08% vs BDL: 78.46 ± 0.28%, p<0.05). Liver function markers, AST and ALT, increased in BDL rats compared to their respective SHAM-operated controls (p<0.001) and were not attenuated following allopurinol treatment. Conclusions: Allopurinol treatment decreased systemic ROS and attenuated brain edema as well as arterial ammonia levels. The effect of allopurinol demonstrates oxidative stress plays a role in ammonia metabolism and in the pathogenesis of brain edema. Our results suggest antioxidant treatment directed towards inhibiting ROS production could be beneficial in lowering ammonia and treating HE. Additional studies are warranted to evaluate the implication of oxidative stress in ammonia metabolism.

Aims: The pathogenesis of hepatic encephalopathy (HE) is multifactorial. Even though ammonia is the central component in the pathogenesis of HE, oxidative stress is believed to play a role in exacerbating the neuropsychological effects of ammonia in patients with liver disease. With new, highly sensitive imaging techniques, brain edema is observed in HE patients. We previously demonstrated that portacaval shunted hyperammonemic rats do not develop oxidative stress or brain edema. In order to define a synergistic effect between hyperammonemia and systemic oxidative stress, the present study investigates the role of oxidative stress in the pathogenesis of brain edema in PCA rats following glutathione depletion by diethyl maleate (DEM). Methods: In the first set of experiments, we evaluated the effect of DEM in PCA and SHAM-operated control rats by injecting DEM at a dose of 0.4 and 1 mg/kg/day intraperitoneally for 10 days starting at day 18 after surgery. Rats were sacrificed at day 28 and oxidative stress was evaluated by arterial malon-dialdehyde (MDA, commercial kit). In the second set of experiments, 1 mg/kg/day DEM was used to induce oxidative stress. Ammonia (commercial kit) as well as other different oxidative stress markers: reactive oxygen species (DCFDA fluorescence technique), and 4-hydroxy-2-nonenal (HNE, Western blot) were assessed in arterial plasma and frontal cortex tissue. Brain water content was measured in the frontal cortex using a specific gravimetric technique. Results: DEM at 1 mg/kg/day (not 0.4 mg/kg/day) induced a significant increase in MDA levels in PCA rats. No increase in MDA was detected following either dose of DEM in SHAM-operated controls. Ammonia levels in both DEM-treated and non-treated PCA rats were significantly increased vs respective sham-operated controls (p<0.001) and remained unchanged between non-treated and DEM-treated PCA groups (p>0.05). An increase in brain water content was observed in DEM-treated PCA rats vs non-treated PCA rats (PCA+DEM: 78.45 ± 0.13% vs PCA: 77.38 ± 0.11, p< 0.001). Although no significant changes in reactive oxygen species were observed, there was an increase in plasma levels of HNE in DEM-treated PCA rats compared to non-treated PCA rats. No significant changes in any oxidative stress markers were observed in the frontal cortex. Conclusions: DEM treatment in PCA rats induced systemic oxidative stress but not central oxidative stress. This, imposed on hyperammonemia, was accompanied by the onset of brain edema in rats with PCA. Oxidative stress and brain edema were not detected in SHAM-operated rats, which were not hyperammonemic. Our findings suggest a synergistic effect between hyperammonemia and systemic oxidative stress is implicated in the pathogenesis of brain edema in hepatic encephalopathy.

Chronic liver failure leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy (HE); however, a correlation between blood ammonia levels and HE severity remains controversial. It is believed oxidative stress plays a role in modulating the effects of hyperammonemia. This study aimed to determine the relationship between chronic hyperammonemia, oxidative stress, and brain edema (BE) in two rat models of HE: portacaval anastomosis (PCA) and bile-duct ligation (BDL). Ammonia and reactive oxygen species (ROS) levels, BE, oxidant and antioxidant enzyme activities, as well as lipid peroxidation were assessed both systemically and centrally in these two different animal models. Then, the effects of allopurinol (xanthine oxidase inhibitor, 100mg/kg for 10days) on ROS and BE and the temporal resolution of ammonia, ROS, and BE were evaluated only in BDL rats. Similar arterial and cerebrospinal fluid ammonia levels were found in PCA and BDL rats, both significantly higher compared to their respective sham-operated controls (p<0.05). BE was detected in BDL rats (p<0.05) but not in PCA rats. Evidence of oxidative stress was found systemically but not centrally in BDL rats: increased levels of ROS, increased activity of xanthine oxidase (oxidant enzyme), enhanced oxidative modifications on lipids, as well as decreased antioxidant defense. In PCA rats, a preserved oxidant/antioxidant balance was demonstrated. Treatment with allopurinol in BDL rats attenuated both ROS and BE, suggesting systemic oxidative stress is implicated in the pathogenesis of BE. Analysis of ROS and ammonia temporal resolution in the plasma of BDL rats suggests systemic oxidative stress might be an important "first hit", which, followed by increases in ammonia, leads to BE in chronic liver failure. In conclusion, chronic hyperammonemia and oxidative stress in combination lead to the onset of BE in rats with chronic liver failure.

Aims: Brain edema is a common occurrence in patients with hepatic encephalopathy (HE) due to chronic liver disease however the underlying pathophysiological mechanisms are weakly described. Hyperammonemia is considered the central component, but levels of plasma ammonia and severity of HE poorly correlate. Oxidative stress and impaired lactate metabolism are pathogenetic factors believed to be involved. This study investigates the temporal resolution of increases in ammonia, oxidative stress and lactate in relation to the development of brain edema in bile-duct ligated rats (BDL), a widely used rat model of chronic liver disease and HE. Methods: Cirrhosis was induced in rats through ligation of the bile duct. Ammonia and reactive oxygen species (ROS) were assessed in arterial plasma using a commercially available kit and a DCFDA-fluorescent technique respectively. Brain water content was measured in the frontal cortex using the specific gravimetric technique and lactate by Amplex Red fluorescence. Measurements were performed in BDL rats vs sham operated controls at 2, 4 and 6 weeks after surgical intervention in plasma and cerebrospinal fluid or brain tissue. Results: See table. Conclusions: Following 2 weeks of BDL, an increase in plasma ROS is observed with no increase in the other factors. Following 4 weeks of BDL, in addition to an increase in systemic ROS, an increase in plasma and brain ammonia and brain (not plasma) lactate is demonstrated however no evidence of brain edema. Brain edema appears at 6 weeks, along with an increase in all 3 factors. The further significant increase in brain lactate and ammonia at 6 weeks compared to 4 weeks, superimposed on systemic oxidative stress, may be responsible the of development of brain edema in BDL rats. Our results support the multifactorial pathogenesis of brain edema in HE and suggests systemic oxidative stress might be an important “first hit”, followed by increases in ammonia and lactate, in the pathogenesis of brain edema in chronic liver failure. SHAMⱡBDL 2 weeksBDL 4 weeksBDL 6 weeks PLASMA AMMONIA(μM)37.24±12.5433.24±16.7371.32±12.03*118.50±10.78* ROS(RFU)0.08±0.032.94±0.39***2.05±0.59***3.68±0.86*** LACTATE(mM)1.40±0.191.22±0.181.21±0.131.75±0.35 CEREBROSPINAL FLUID AMMONIA(μM)36.12±13.2335.94±9.6389.38±13.07*128.4±36.66*** ROS(RFU)26.11±9.9423.95±12.2613.61±1.6325.97±8.21 BRAIN TISSUE LACTATE(μM/ 100 g proteins)88.51±5.2698.06±7.78190.26±26.14*254.60±10.12*** BRAIN EDEMA (%)78.05±0.1477.73 ±0.0777.69±0.0779.03±0.31* ⱡ mean value of SHAM-operated rats 2, 4 and 6 weeks *p<0.05 vs SHAM ***p<0.01 vs SHAM $p<0.05 vs BDL 4 weeks

Background: Liver disease leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy (HE). There is increasing evidence systemic oxidative stress may exacerbate the neuropsychological effects of hyperammonemia in patients with liver disease. With new highly sensitive imaging techniques, brain edema is frequently being observed in patients cirrhosis and HE. Six-week cirrhotic rats develop brain edema, hyperammonemia and also an increase in plasma reactive oxygen species (ROS) along with an increase in xanthine oxidase activity. In order to better understand the relationship between oxidative stress and ammonia and their role in the pathogenesis of brain edema, we evaluated the effect of allopurinol, a xanthine oxidase inhibitor, in rats with cirrhosis. Methods: Secondary biliary cirrhosis was induced in rats by bile duct ligation (BDL) for 6 weeks. BDL and SHAM-operated rats received 100 mg/kg/day of allopurinol for 10 days. A group of BDL and SHAM-operated rats received saline. AST and ALT were measured at the end of the treatment period to assess liver function. Ammonia and ROS were assessed in arterial plasma using a commercially available kit and a DCFDA-fluorescent technique respectively. Brain water content was measured in the frontal cortex using the specific gravimetric technique. Results: Arterial ROS and ammonia levels were significantly increased in BDL vs SHAM-operated rats (p<0.001). BDL rats treated with allopurinol demonstrated a significant decrease in systemic ROS as well as ammonia levels vs non-treated BDL rats (1.70 ± 0.53RFU vs 4.97 ± 1.38RFU, p<0.05, 37.9 ± 13.8µM vs 101.1 ± 10.1µM, p<0.001, respectively), reaching values similar to those seen in SHAM-operated rats. Brain water content increased in BDL vs SHAM-operated rats and normalised in allopurinol treated BDL rats (77.20 ± 0.08% vs BDL: 78.46 ± 0.28%, p<0.05). Liver function markers, AST and ALT, increased in BDL rats compared to their respective SHAM-operated controls (p<0.001) and were not attenuated following allopurinol treatment. Conclusions: Allopurinol treatment decreased systemic ROS and attenuated brain edema as well as arterial ammonia levels. The effect of allopurinol demonstrates oxidative stress plays a role in ammonia metabolism and in the pathogenesis of brain edema. Our results suggest antioxidant treatment directed towards inhibiting ROS production could be beneficial in lowering ammonia and treating HE. Additional studies are warranted to evaluate the implication of oxidative stress in ammonia metabolism.

Background: Brain edema is a serious complication associated with hepatic encephalopathy (HE) due to chronic liver failure (CLF) and its pathogenesis remains undefined. NKCC1, a Na-K-Cl cotransporter, located on the blood-brain barrier (BBB) has been demonstrated to be implicated in the pathogenesis of brain edema in experimental models of ischemia. Therefore, our aim was to 1) investigate the relationship of hyperammonemia, 2) study the integrity of the BBB and 3) determine the role of NKCC1, in association with brain edema in rats with CLF. Methods: Two distinct animal models of CLF and HE were used; i) biliary cirrhosis model (6 weeks bile duct ligation (BDL)) ii) portacaval shunt model (4 weeks portacaval anastomosis (PCA)). Brain water content was measured using the specific gravimetric method. BBB breakdown was assessed by measuring brain extravasation of injected BBB permeability tracers (Evans blue and sodium fluorescein). Expression of BBB tight junction proteins (occludin, claudin-5, ZO-1 and ZO-2) were assessed by immunoblot. Levels of brain NKCC1 mRNA were evaluated by RT-PCR in isolated cerebral microvessels. Rats were treated with bumetanide (an NKCC inhibitor; administered (i.p) for 10 days). Results: Similar degree of hyperammonemia was measured in both BDL and PCA rats however brain edema was only found in BDL rats. In brains of both BDL and PCA rats, extravasation of Evans blue and sodium fluorescein was not detected and no significant change in the levels of all tight junction proteins was found. Brain water content was reduced in bumetanide-treated BDL vs BDL-non treated (77.35±0.18% vs 78.89±0.25%). A 2.4 fold increase in NKCC1 mRNA was detected in BDL vs BDL-sham rats whereas no change was found in PCA vs PCA-sham rats. Conclusions: Chronic hyperammonemia independently does not lead to an increase in brain water. Brain edema, present in BDL rats, is not associated with a change in either BBB integrity or expression of BBB tight junction proteins and is therefore not of vasogenic origin. Furthermore, an increase in NKCC1 mRNA and attenuation of brain edema following bumetanide treatment, suggests NKCC1, independent of hyperammonemia, plays a role in the development of brain edema in CLF.

Aims: Brain edema represents a constant finding in patients with hepatic encephalopathy (HE) due to chronic liver failure; however its pathogenetic mechanisms are poorly described. Hyperammonemia is considered the central component in the pathogenesis of HE, but ammonia levels are not correlated with severity of HE. Other factors such as oxidative stress and impaired lactate metabolism are believed to be involved. Temporal resolution of these factors involved in the progression of the disease and brain edema might elucidate the relationship between these pathogenetic factors. The present study investigates temporal resolution of ammonia, oxidative stress and lactate in relation to the development of brain edema in bile-duct ligated rats (BDL), a widely used rat model of chronic liver failure and HE. Methods: Ammonia (commercial kit), reactive oxygen species (ROS) (DCFDA fluorescence), lactate (Amplex Red fluorescence) and brain edema (specific gravimetric technique) were measured in BDL rats vs sham operated controls at 2, 4 and 6 weeks after surgical intervention in plasma and cerebrospinal fluid or brain tissue. Results: See table.Conclusions: Following 2 weeks of BDL, an increase in plasma oxidative stress is observed with no appearance of hyperammonemia, hyperlactataemia, increased brain lactate and ammonia or brain edema. Following 4 weeks of BDL, in addition to an increase in systemic oxidative stress, an increase in plasma and brain ammonia and brain (not plasma) lactate is demonstrated but still no evidence of brain edema. Brain edema appears at 6 weeks, along with an increase in all 3 pathogenetic factors. The further increase in brain lactate and ammonia compared to 4 weeks, superimposed on systemic oxidative stress, may be responsible the development of brain edema in BDL rats. Our results support the multifactorial pathogenesis of brain edema in HE and suggests systemic oxidative stress might be an important “first hit”, followed by increases in ammonia and lactate, in the pathogenesis of brain edema in chronic liver failure.

Aims: Chronic liver failure leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy (HE). Neurotoxic effects of ammonia induce numerous metabolic alterations such as increased brain lactate (Lac) and glutamine (Gln) levels. Brain edema is present in patients with chronic liver failure however the pathophysiological mechanisms are not clearly understood. The present study investigates the role of brain ammonia, Lac and Gln in pathogenesis of brain edema in 2 different rat models of chronic liver failure/HE; 1) portacaval anastomosis (PCA), and 2) bile-duct ligation (BDL). Methods: Ammonia (commercial kit), brain edema (specific gravimetric technique) Lac (Amplex Red fluorescence) and Gln (1H nuclear magnetic spectroscopy) were measured in brain tissue of PCA and BDL rats vs sham operated controls. De novo synthesis of Lac and Gln was assessed in brain tissue by 13C nuclear magnetic resonance spectroscopy, after injecting PCA and BDL rats along with their respective sham operated controls with [U-13C] glucose (500 mg/kg, i.p) 30 minutes before sacrifice. Lac, Gln and brain edema were also investigated in BDL rats at 2, 4 and 6 weeks after surgery and after reducing ammonia levels with AST-120 (spherical carbon adsorbent), at 1g/kg/day for 6 weeks. Results: Hyperammonemia developed in both PCA (177.3±8.9μM vs sham: 52.1±11.3μM; p<0.0001) and BDL (155.0±8.9μM vs sham: 41.0±11.2μM; p<0.0001); with no significant difference between the groups. An increase in brain water content was observed in rats with BDL (81.88±0.12% vs sham: 81.13±0.15%, p<0.05), as well as total Lac levels; whereas no significant change in brain water and total Lac was found in PCA. Gln levels significantly increased in PCA rats and BDL rats vs respective sham-operated controls. A significant increase in de novo synthesis of 13C Lac and 13C Gln from 13C glucose was found in BDL rats, whereas in PCA rats only de novo synthesis of 13C Gln increased. In addition, total Lac levels were increased in BDL rats before the apparition of brain edema. Following AST-120 treatment, Lac levels and brain edema significantly decreased, while Gln levels remained unchanged. Conclusions: BDL and PCA rats both presented with similar levels of hyperammonemia and Gln, as well as increased de novo synthesis of Gln from glucose. However only BDL rats demonstrated an increase in brain water and Lac as well as increased de novo synthesis of Lac from glucose. Our findings suggest increased brain Lac, not increased brain Gln, is associated with brain edema. We conclude that impaired Lac metabolism may contribute to the pathogenesis of brain edema in HE.

Aims: Brain edema is a serious complication associated with hepatic encephalopathy (HE) due to chronic liver failure. It is unclear whether brain edema is of vasogenic (blood brain barrier (BBB) breakdown) or of cytotoxic (disturbance of neurocellular metabolism) origin. It has been demonstrated that the Na-K-Cl cotransporter (NKCC) located on the luminal side of the BBB is implicated in the pathogenesis of brain edema in different animal models of ischemia. Furthermore, following the administration of bumetanide, an inhibitor of NKCC, brain edema is attenuated. Therefore, our aim was to study the BBB integrity and the role of NKCC in the pathogenesis of brain edema in cirrhotic rats. Methods: Two distinct animal models of chronic liver failure and HE are used in the present study; 1) biliary cirrhosis model (6 weeks bile duct ligation (BDL)). 2) portacaval shunt model (4 weeks portacaval anastomosis (PCA)). Both models develop hyperammonemia however brain edema is only observed in BDL. BBB breakdown was assessed by measuring brain extravasation of BBB permeability tracers. Evans blue and sodium fluorescein were injected (i.v), brains were perfused and extravasation was determined by spectophotometry. Expression of BBB tight junction proteins (occludin, claudin-5, ZO-1 and ZO-2) were assessed by immunoblot. Bumetanide was administered (i.p) for 10 days in BDL and BDL SHAM. Brain water content was measured in the frontal cortex using the specific gravimetric method. Levels of brain NKCC mRNA were evaluated by RT-PCR in microvessels isolated using centrifugation methods. Results: Extravasation of Evans blue and sodium fluorescein was not detected and there was no significant change in all tight junction protein levels measured in both BDL and PCA (negative control) models. Brain water content was reduced in bumetanide-treated BDL rats compared to control (77.66±0.15% vs 78.12±0.21%). In brain microvessels, NKCC mRNA increased in BDL rats compared to BDL SHAM (0.78±0.09 vs. 1.92±0.42) whereas no change was found in PCA compared to PCA SHAM (1.72±0.52 vs. 1.53±0.23). Conclusions: BDL rats did not demonstrate a change in BBB integrity or a change in expression of BBB tight junction proteins. This suggests brain edema in BDL is not of vasogenic origin. Moreover, an increase of NKCC mRNA and an attenuation of brain edema following bumetanide treatment were demonstrated in BDL rats suggesting NKCC plays a role in the development of brain edema in chronic liver failure.

The pathogenesis of hepatic encephalopathy is multifactorial, involving gut-derived toxins such as ammonia, which has been demonstrated to induce oxidative stress. Therefore, a primary hepatic encephalopathy treatment target is reducing ammonia production in the gastrointestinal tract. AST-120, an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600 m(2) /g, acts as a sink for neurotoxins and hepatotoxins present in the gut. We evaluated the capacity of AST-120 to adsorb ammonia in vitro and to lower blood ammonia, oxidative stress and brain edema in cirrhotic rats. Cirrhosis was induced in rats by bile duct ligation for 6 weeks. AST-120 was administered by gavage preventively for 6 weeks (0.1, 1, and 4 g/kg/day). In addition, AST-120 was evaluated as a short-term treatment for 2 weeks and 3 days (1 g/kg/day) and as a sink to adsorb intravenously infused ammonium acetate. In vitro, AST-120 efficiently adsorbed ammonia. Ammonia levels significantly decreased in a dose-dependent manner for all AST-120-treated bile duct-ligated rats (nontreated: 177.3 ± 30.8 μM; AST-120, 0.1 g/kg/day: 121.9 ± 13.8 μM; AST-120, 1 g/kg/day: 80.9 ± 30.0 μM; AST-120, 4 g/kg/day: 48.8 ± 19.6 μM) and significantly correlated with doses of AST-120 (r = -0.6603). Brain water content and locomotor activity normalized after AST-120 treatments, whereas arterial reactive oxygen species levels remained unchanged. Furthermore, AST-120 significantly attenuated a rise in arterial ammonia after ammonium acetate administration (intravenously). Conclusion:AST-120 treatment decreased arterial ammonia levels, normalized brain water content and locomotor activity but did not demonstrate an effect on systemic oxidative stress. Also, AST-120 acts as an ammonia sink, efficiently removing blood-derived ammonia. Additional studies are warranted to evaluate the effects of AST-120 on hepatic encephalopathy in patients with advanced liver disease. (HEPATOLOGY 2011;).

Introduction: L’insuffisance hépatique mène à l’hyperammonémie, la composante centrale dans la pathogénèse de l’encéphalopathie hépatique (EH). Les niveaux neurotoxiques d’ammoniaque induisent des nombreuses altérations métaboliques telles que l’augmentation du lactate et glutamine au niveau cérébral. Des nouvelles techniques d’imagerie ont démontré que l’œdème cérébral est présent chez les patients avec insuffisance hépatique chronique, mais les mécanismes pathophysiologiques ne sont pas bien connus. Dans cette étude, nous avons investigué l’implication de la synthèse de novo du lactate et glutamine dans la pathogénèse de l’œdème cérébral en utilisant 2 modèles différents d’insuffisance hépatique chronique/EH chez le rat: 1) la dérivation portosystémique (PCA); et 2) la ligature de voie biliaire (BDL). Méthodes: Des rats PCA et BDL, ainsi que contrôles SHAM-opérés ont été injectés avec [U-13C] glucose (500 mg/kg, i.p) et sacrifiés après 30 minutes. Les niveaux totaux, ainsi que la synthèse de novo de glutamine et du lactate ont été mesurés dans le tissu cérébral par spectroscopie de résonance magnétique nucléaire 1H et 13C. L’ammoniaque a été mesurée dans le plasma artériel et le liquide céphalorachidien par un kit commercial. Le contenu en eau du cerveau a été mesuré dans le cortex frontal par une technique spécifique gravimétrique. Résultats: L’hyperammonémie s’est développée dans les deux groupes; PCA: 177.3 ± 8.9 μM vs SHAM: 52.1 ± 11.3 μM; p<0.001 et BDL: 155.0 ± 8.9 μM vs SHAM: 41.0 ± 11.2 μM; p<0.001, sans différence significative entre les 2 groupes. Des résultats similaires ont été observés dans le liquide céphalorachidien; PCA: 179.5 ± 10.3 μM vs SHAM: 34.9 ± 6.3 μM; p<0.001 et BDL: 142.6 ± 28.3 μM vs SHAM: 27.9 ± 4.9 μM; p<0.001. Le contenu en eau du cerveau a augmenté dans les rats BDL (BDL: 81.88 ± 0.12% vs SHAM: 81.13 ± 0.15%, p<0.05), par contre dans les rats PCA il n’y avait pas une différence significative comparativement au rats SHAM-opérés. Les niveaux de glutamine étaient augmentés 3 fois chez les rats PCA vs SHAM et 2 fois chez les rats BDL vs SHAM. Une augmentation significative de la synthèse de novo du 13C lactate et 13C glutamine provenant du 13C glucose administré a été observée chez les BDL (1.6 fois, respectivement 2 fois vs SHAM), tandis que chez les rats PCA seulement une augmentation de la synthèse de novo de 13C glutamine a été observée. Conclusions: Les rats PCA et BDL présentent des taux similaires d’ammoniaque plasmatique et cérébral et une augmentation de la synthèse de novo de glutamine cérébrale provenant du glucose, mais seulement les rats BDL présentent l’œdème cérébral ainsi qu’une augmentation de la synthèse de novo du lactate cérébral provenant du glucose. Nos résultats suggèrent que le lactate est un important facteur dans la pathogénèse de l’œdème cérébral dans l’insuffisance hépatique chronique. Projet subventionné par: Instituts de recherche en santé du Canada

Objectif : L’œdème cérébral est un symptôme sévère de l’encéphalopathie hépatique (EH) lors d’une insuffisance hépatique chronique. La cause de l’œdème cérébral est ambigüe parce qu’elle peut être de type vasogénique, la rupture des jonctions serrées de la barrière hémato-encéphalique (BHE), ou de type cytotoxique, la perturbation du métabolisme neurocellulaire. Plusieurs recherches démontrent que le cotransporteur Na-K-Cl 1 (NKCC1) serait impliqué dans la pathogénèse de l’œdème cérébral dans différents modèles animaux d’ischémie cérébrale et qu’un traitement avec de la bumetanide, un inhibiteur de NKCC1, atténue l’augmentation d’eau dans le cerveau. Ainsi, notre objectif était d’étudier l’intégrité de la BHE et le rôle de NKCC1 dans la pathogénèse de l’œdème cérébral chez des rats cirrhotiques. Méthodes : Deux modèles animaux d’insuffisance hépatique chronique sont utilisés dans cette étude. Le premier modèle (cirrhose biliaire de 6 semaines (BDL)), est une ligature de la voie biliaire. Alors, la bile synthétisée par les hépatocytes s’accumule dans le foie et provoque la cirrhose du foie. Ce modèle présente une hyperammonémie et du stress oxydatif plasmatique ainsi que l’œdème cérébral. Le deuxième modèle (dérivation portocave de 4 semaines (PCA)), est une anastomose de la veine porte à la veine cave inférieure. Ainsi, le sang provenant du système digestif n’est pas filtré par le foie, ce qui provoque une hyperammonémie mais elle n'est pas accompagnée par une induction de stress oxydatif et d’œdème cérébral alors ce sera un contrôle négatif. Pour déterminer la perméabilité générale de la barrière hémato-encéphalique, l’extravasation de l’Evans blue, un colorant qui se lie aux protéines (dont l’albumine sérique), et du fluorophore, fluorescéine de sodium, a été évaluée par spectrophotométrie et l’expression des protéines des jonctions serrées (occludin, claudin-5, ZO-1, ZO-2) a été mesurée par immunobuvardage dans les deux modèles. La bumetanide a été administrée i.p pendant 10 jours chez les BDL et BDL SHAM. La quantité d’eau dans le cortex cérébral a été mesurée par gravimétrie. L’expression d’ARNm de NKCC1 a été mesurée dans les microvaisseaux sanguins isolés à partir de cerveaux des deux modèles à l’aide d’un protocole de centrifugation. Résultats : L’extravasation des colorants n’a pas été détectée et l’expression des protéines de jonctions serrées est demeurée inchangée dans les deux modèles. L’œdème cérébral a été atténué lorsque la bumetanide a été administrée chez les BDL comparé aux contrôles (77.66±0.15% vs 78.12±0.21%). Dans les microvaisseaux sanguins cérébraux, le niveau d’ARNm de NKCC1 était augmenté chez les BDL comparé aux BDL SHAM (1.92±0.42 vs. 0.78±0.09) tandis qu’il restait inchangé chez les PCA comparé aux PCA SHAM (1.72±0.52 vs. 1.53±0.23). Conclusion : L’extravasation est absente et l’expression des protéines de jonctions serrées est inchangée donc l’œdème cérébral n’est pas de type vasogénique. L’augmentation d’ARNm de NKCC1 et l’atténuation de l’œdème cérébral par la bumetanide suggèrent que l’œdème cérébral est de type cytotoxique chez les rats avec une insuffisance hépatique chronique.

Background: Chronic liver failure leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy. Neurotoxic effects of ammonia have been shown to induce numerous metabolic alterations such as increased brain lactate and glutamine levels. Newly developed imaging techniques have demonstrated brain edema is present in patients with chronic liver failure however the pathophysiological mechanisms are not clearly understood. The present study investigates the role of de novo synthesis of brain lactate and glutamine in pathogenesis of brain edema in 2 different rat models of chronic liver failure/hepatic encephalopathy; 1) portacaval anastomosis (PCA), and 2) bile-duct ligation (BDL). Methods: PCA and BDL rats along with their respective sham-operated controls were injected with [1-13C] glucose (500 mg/kg, i.p) and sacrificed 30 minutes later. Glutamine and lactate were assessed in brain tissue by 1H and 13C nuclear magnetic resonance spectroscopy. Ammonia levels were measured in arterial plasma and cerebrospinal fluid using a commercially available kit. Brain water content was measured in frontal cortex using a specific gravimetric technique. Results: Hyperammonemia developed in both PCA (177.3 ± 8.9μM vs sham: 52.1 ± 11.3μM; p< 0.0001) and BDL (155.0 ± 8.9μM vs sham: 41.0 ± 11.2μM; p< 0.0001); with no significant difference between the groups (p> 0.05). Similar results were found in cerebrospinal fluid (PCA: 179.5 ± 10.3μM vs sham: 34.9 ± 6.3μM; p< 0.0001 and BDL: 142.6 ± 28.3μM vs sham: 27.9 ± 4.9μM; p< 0.0001); with no significant difference between the groups (p> 0.05). An increase in brain water content was observed in rats with BDL (81.88 ± 0.12% vs sham: 81.13 ± 0.15%, p< 0.05) whereas no significant change in brain water content was found in PCA vs their respective sham-operated controls. Glutamine levels significantly increased 3 fold in PCA rats and 2 fold in BDL rats vs respective sham-operated controls. A significant increase in de novo synthesis of 13C lactate and 13C glutamine from 13C glucose was found in BDL rats (1.6 fold and 2 fold respectively vs sham), whereas in PCA rats only de novo synthesis of 13C glutamine increased. Conclusion: BDL and PCA rats both presented with similar levels of hyperammonemia and increased brain ammonia, increased de novo synthesis of glutamine from glucose however only BDL rats demonstrated an increase in brain water as well as an increase in de novo synthesis of lactate from glucose. Our findings suggest lactate is an important pathogenic factor implicated in the pathogenesis of brain edema in chronic liver failure.

Background: Ammonia is central in the pathogenesis of hepatic encephalopathy (HE) and clinical sequelae are exacerbated by systemic inflammation. Sequestration of ammonia in the gut represents a primary treatment target for HE. AST-120 (spherical carbon adsorbent), an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600m2/g works as a sink for neuro- and hepato–toxins present in the gut. In this study, we evaluated the capacity of AST-120 to lower arterial ammonia, brain edema and systemic inflammatory markers in cirrhotic rats. Methods: Cirrhosis was induced in rats by bile duct ligation (BDL). BDL and SHAM-operated rats received AST-120 dispersed in methylcellulose by gavage at a dose of 0.1, 1 or 4g/kg/day for 6 weeks. Ammonia and the pro-inflammatory cytokine TNF-α were measured in arterial plasma using a commercially available kit and ELISA technique respectively. Brain water content was measured in the frontal cortex, cerebellum and brain stem using the specific gravimetric technique. Results: Arterial ammonia increased in non-treated BDL vs SHAM-operated controls (166.9±21.1uM vs 70.5±14.4uM, p<0.01). All doses of AST-120 decreased ammonia in BDL to similar levels found in respective SHAM-operated controls; 0.1g/kg/day (117.2±12.6uM vs 100.4±7.3uM, p>0.05); 1g/kg/day (78.9±22.3uM vs 78.1±8.9uM, p>0.05) and 4g/kg/day (48.8±19.6uM vs 49.9±14.7uM, p>0.05). Ammonia levels significantly correlated with doses of AST-120 (r=-0.66, p<0.0001). Brain water content increased in frontal cortex, cerebellum and brain stem in BDL vs SHAM-operated and was normalized in all AST-120 treatment groups compared to respective controls. Circulating levels of TNF-α were significantly increased in BDL vs SHAM-operated rats (p<0.05). AST-120 treatment did not attenuate TNF-α levels compared to respective SHAM-operated controls. Conclusion: AST-120 treatment dose-dependently decreased arterial ammonia levels, which resulted in normalization of multi-foci brain edema. This response was not correlated with differences in levels of circulating TNF-α. AST-120 treatment is a safe, non-antibiotic alternative demonstrating a significant ammonia-lowering effects, as well as a protective effect on the development of brain edema in rats with chronic liver disease. AST-120 represents a useful tool to elucidate further the relationship between circulating ammonia and gut-derived or systemic inflammatory components of liver disease.

AIMS: The pathogenesis of hepatic encephalopathy (HE) is multifactorial involving gut-derived toxins such as ammonia. Liver disease leads to hyperammonemia and neurotoxic levels of ammonia which have been demonstrated to induce oxidative stress. Therefore a primary treatment target for HE is to decrease ammonia production in the gastrointestinal tract. AST-120 (spherical carbon adsorbent), an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600m2/g acts as a sink for neuro- and hepato-toxins present in the gut. In this study, we evaluated the protective effect of AST-120 in lowering arterial ammonia and oxidative stress and in attenuating brain edema in rats with cirrhosis. METHODS: Secondary biliary cirrhosis was induced in rats by bile-duct ligation (BDL) for 6 weeks. BDL and SHAM-operated rats received AST120 (dispersed in methylcellulose (MC)) by gavage at a dose of 0.1, 1 or 4g/kg/day for 6 weeks. Control BDL and SHAM-operated groups received MC only. AST and ALT were measured to assess liver function. Ammonia and reactive oxygen species (ROS) were measured in arterial plasma using a commercially available kit and DCFDA-fluorescent technique respectively. Brain water content was measured in the frontal cortex using the specific gravimetric technique. RESULTS: AST-120 was well-tolerated with no deaths in either of the treatment groups. Brain water content increased in BDL vs SHAM-operated rats (79.2±0.2% vs 78.7±0.1%, p<0.05). All AST-120 treatments, 0.1, 1 and 4g/kg/day, normalised brain water content in BDL rats. Arterial ammonia levels increased in the BDL control group vs SHAM-operated controls (169.9±21.1uM vs 70.5±14.4uM, p<0.05) and decreased significantly to SHAM levels in 0.1g/kg/day (117.2±12.6uM, p<0.05), 1g/kg/day (78.9±22.3uM, p<0.05) and 4g/kg/day (48.7±19.5uM, p<0.05) AST-120 treated BDL rats. Circulating levels of ROS were significantly increased in BDL vs SHAM-operated rats (11 fold, p<0.001). AST-120 treatments did not attenuate arterial levels of ROS compared to respective SHAM-operated controls. Liver functions enzymes, AST and ALT, were increased in all BDL rats compared to their respective SHAM-operated controls (p<0.001) but were not attenuated following AST120 treatments. CONCLUSIONS: AST-120 treatment normalized brain water content and decreased arterial ammonia levels but did not demonstrate an effect on systemic ROS. Long-term treatment with AST-120 is a safe, non-antibiotic alternative with significant ammonia-lowering effect as well as a protective effect on the development of brain edema in rats with chronic liver failure. Additional studies are warranted to evaluate the effects of AST-120 on HE in patients with advanced liver disease.

Ammonia is neurotoxic and believed to play a major role in the pathogenesis of hepatic encephalopathy (HE). It has been demonstrated, in vitro and in vivo, that acute and high ammonia treatment induces oxidative stress. Reactive oxygen species (ROS) are highly reactive and can lead to oxidization of proteins resulting in protein damage. The present study was aimed to assess oxidative status of proteins in plasma and brain (frontal cortex) of rats with 4-week portacaval anastomosis (PCA). Markers of oxidative stress, 4-hydroxy-2-nonenal (HNE) and carbonylation were evaluated by immunoblotting in plasma and frontal cortex. Western blot analysis did not demonstrate a significant difference in either HNE-linked or carbonyl derivatives on proteins between PCA and sham-operated control rats in both plasma and frontal cortex. The present study suggests PCA-induced hyperammonemia does not lead to systemic or central oxidative stress.

Introduction: La pathogénèse de l'encéphalopathie hépatique (EH) est multifactorielle et implique des toxines provenant des intestins, telle que l'ammoniaque. L'insuffisance hépatique mène à l'hyperammonémie et aux niveaux neurotoxiques d’ammoniaque qui peuvent induire le stress oxydatif. Ainsi, la première cible du traitement de l'EH est la diminution de la production intestinale d'ammoniaque. AST-120 (adsorbant sphérique de charbon), un adsorbant oral de microsphères activées par ingénierie ayant une surface de plus de 1600m2/g, adsorbe les neuro- et hépato-toxines présentes dans les intestins. Dans cette étude, nous avons évalué l'effet protecteur d'AST-120 sur l'œdème cérébral et sa capacité à diminuer l'ammoniaque artérielle et le stress oxydatif chez les rats cirrhotiques. Méthodes: La cirrhose a été induite par la ligature de la voie biliaire (BDL) pour 6 semaines. Les rats BDL et SHAM ont reçu durant 6 semaines une dose d'AST-120 de 0.1 et 1mg/kg/jour dispersé dans la méthylcellulose (MC) par gavage. Des rats contrôles BDL et SHAM ont reçu seulement le véhicule. L'AST et ALT ont été mesurés à la fin du traitement pour évaluer la fonction du foie. L'ammoniaque et les espèces réactives d'oxygène (ROS) ont été mesurées dans le plasma artériel par un kit commercial et une technique de fluorescence. Le contenu en eau du cerveau a été mesuré dans le cortex frontal par une technique spécifique gravimétrique. Résultats: Le traitement avec AST-120 a été bien toléré. Les marqueurs de la fonction hépatique, AST et ALT, étaient augmentés dans tous les groupes de rats BDL vs SHAM (p<0.001). Le contenu en eau du cerveau a augmenté dans les rats BDL (BDL: 81.8±0.1% vs SHAM: 81.3±0.2%, p<0.05). Les deux dosages d'AST-120 de 0.1 et 1mg/kg/jour ont normalisé le contenu en eau du cerveau dans les rats BDL. L'ammoniaque artérielle était augmentée chez les rats BDL (175.5± 48.1uM vs SHAM: 105.3±27.3uM, p<0.05) et diminuée significativement dans les BDL 0.1mg/kg/jour (118.0±6.4uM, p<0.05) et BDL 1mg/kg/jour (75.4±31.4uM, p<0.05). Les niveaux de ROS étaient augmentés chez les rats BDL vs SHAM (augmentation de 11 fois vs SHAM). AST-120 n'a pas diminué les niveaux plasmatiques de ROS comparativement aux SHAM. Conclusions: Le traitement avec AST-120 normalise le contenu en eau du cerveau et diminue les niveaux artériels d'ammoniaque, mais n'a pas d'effet sur les ROS systémiques. AST-120 administré à long terme a été prouvé une alternative sûre de traitement non-antibiotique pour l'EH, en démontrant un effet significatif sur la diminution de l'ammoniaque, en même temps qu'un effet protecteur sur l'œdème cérébral chez les rats avec ligature de voie biliaire. Projet subventionné par: Instituts de recherche en santé du Canada et Ocera Therapeutics Inc. (CA, USA)

Introduction: L'ammoniaque joue un rôle majeur dans la pathogénèse de l'encéphalopathie hépatique. Le stress oxydatif est toutefois également proposé d'être impliqué. Des études récentes sont à l'origine de notre projet : 1) la concentration neurotoxique d'ammoniaque induisant le stress oxydatif a été démontrée in vitro et 2) le stress oxydant systémique exacerbe les effets neuropsychologiques de l'hyperammonémie observée chez les patients atteints d’une maladie hépatique. Notre étude vise à mesurer le stress oxydant systémique et central en association avec l'œdème cérébral chez les rats atteints de cirrhose. Méthodes: Les rats ont été sacrifiés six semaines après la ligature de la voie biliaire (bile-duct ligation, BDL), induisant une cirrhose. Le plasma artériel et le liquide céphalo-rachidien (LCR) ont été prélevés afin de mesurer l'ammoniaque (kit commercial), les espèces réactives de l'oxygène (ROS, technique de fluorescence DCFDA), l'oxyde nitrique (NO, méthode de Griess) et la peroxydation lipidique (malondialdéhyde, MDA, kit commercial). Le cortex frontal a été disséqué pour mesurer l'activité de la catalase (antioxydant, technique de fluorescence avec l'Amplex Red) et les dérivés de S-nitrosylation du résidu cystéine (immunobuva^rdage). Le volume en eau du cerveau a été déterminé en utilisant la technique gravimétrique spécifique. Résultats: Le volume en eau du cerveau a augmenté dans les rats avec BDL vs sham-contrôles (81.91 ± 0.19% vs 81.23 ± 0.20%, p <0.05). Les rats avec BDL ont développé, vs les sham-contrôles, une augmentation plasmatique de concentration d'ammoniaque (91.8 µM ± 18.4 vs 41.2 µM ± 13.2, p<0.05), de NO (2.9 fois plus élevé), de ROS (4.9 fois plus élevé), de MDA (41.9 µM ± 7.4 vs 9.9 µM ± 0.6, p<0.005) et de dérivés de S-nitrosylation du résidu cystéine, ainsi qu'une diminution de l'activité de la catalase (1.3 U/ml ± 0.5 vs 3.2 U/ml ± 1.4, p<0.05). Dans le système nerveux central, les rats avec BDL (vs sham-contrôles) ont développé une augmentation de l'ammoniaque dans le LCR (123.5 µM ± 21.7 vs 23.3 µM ± 6.1, p<0.05) mais n'ont pas développé une augmentation de ROS et de NO dans le LCR ou une augmentation de MDA et de dérivés de S-nitrosylation du résidu cystéine dans le cerveau. En outre, l'activité de la catalase dans le cerveau est restée inchangée dans les rats avec BDL. Conclusions: Six semaines après la ligature de la voie biliaire, les rats ont développé un œdème cérébral. L'augmentation de l'ammoniaque artérielle a été accompagnée d'une élévation du NO, des ROS, de la peroxydation lipidique et de la S-nitrosylation, ainsi qu'une diminution de l'activité de la catalase. Toutefois, une hausse du niveau d'ammoniaque dans le LCR conduit à des résultatss inverses dans le cerveau, où aucune augmentation des marqueurs du stress oxydatif n'a été trouvée. Nos résultatss suggèrent que 1) l'ammoniaque n'induit pas le stress oxydatif dans le cerveau, 2) le stress oxydatif systémique est liée à une diminution de l'activité de la catalase et 3) l'œdème cérébral chez les rats avec BDL est associé à un stress oxydatif systémique, et non central.

Background: The pathogenesis of hepatic encephalopathy (HE) is multifactorial involving gut-derived toxins such as ammonia. Liver disease leads to hyperammonemia and neurotoxic levels of ammonia which have been demonstrated to induce oxidative stress. Therefore a primary treatment target for HE is to decrease ammonia production in the gastrointestinal tract. AST-120 (spherical carbon adsorbent), an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600m2/g works as a sink for neuro- and hepato–toxins present in the gut. In this study, we evaluated the protective effect of AST-120 in attenuating brain edema and the capacity of AST-120 to lower arterial ammonia and oxidative stress in rats with cirrhosis. Methods: Secondary biliary cirrhosis was induced in rats by bile duct ligation (BDL) for 6 weeks. BDL and SHAM-operated rats received AST-120 by gavage in methylcellulose (MC) at a dose of 0.1 or 1g/kg/day for 6 weeks. Control BDL and SHAM-operated groups received MC only. AST and ALT were measured at the end of the treatment period to assess liver function. Ammonia and reactive oxygen species (ROS) were measured in arterial plasma using a commercially available kit and DCFDA-fluorescent technique respectively. Brain water content was measured in the frontal cortex using the specific gravimetric technique. Results: AST-120 was well-tolerated with no deaths in either of the treatment groups. Brain water content increased in BDL vs SHAM-operated rats (81.8 ± 0.1% vs 81.3 ± 0.2%, p<0.05). Both 0.1 and 1g/kg/day AST-120 treatments normalised brain water content in BDL rats. Arterial ammonia increased in the BDL control group vs SHAM-operated controls (175.5 ± 48.1uM vs 105.3 ± 27.3uM, p<0.05) and decreased significantly in BDL 0.1g/kg/day (118.0 ± 6.4uM, p<0.05) and BDL 1g/kg/day (75.4 ± 31.4uM, p<0.05). Circulating levels of ROS were significantly increased in BDL vs SHAM-operated rats (11 fold, p<0.001). AST-120 treatment did not attenuate arterial levels of ROS compared to respective SHAM-operated controls. Liver functions enzymes, AST and ALT, were increased in all BDL rats compared to their respective SHAM-operated controls (p<0.001). Conclusions: AST-120 treatment normalized brain water content and decreased arterial ammonia levels but did not demonstrate an effect on systemic ROS. Long-term treatment with AST-120 is a safe, non-antibiotic alternative demonstrating a significant ammonia-lowering effect, as well as a protective effect on the development of brain edema in rats with chronic liver failure. Additional studies are warranted to evaluate the effects of AST-120 on HE in patients with advanced liver disease.

Background: Ammonia plays a major role in the pathogenesis of hepatic encephalopathy however oxidative stress is also believed to be involved. Two lines of evidence lead us to the following aim of our study: 1) neurotoxic levels of ammonia have demonstrated to induce oxidative stress in vitro and 2) systemic oxidative stress is believed to exacerbate the neuropsychological effects of hyperammonemia observed in patients with liver disease. Our aim was to measure oxidative stress markers systemically and centrally, in association with brain edema in rats with cirrhosis. Methods: Rats were sacrificed 6 weeks following bile-ligated induced cirrhosis. Arterial plasma and cerebrospinal fluid (CSF) were collected to measure ammonia (commercially available kit), reactive oxygen species (ROS) (DCFDA-fluorescent technique), nitric oxide (NO) (Griess method) and lipid peroxidation (malondialdehyde, MDA) (commercially available kit). Frontal cortex was dissected to measure antioxidant catalase activity (Amplex Red fluorescent technique), S-nitrosylation of cystein thiols (immunoblotting) and brain water content was determined using the specific gravimetric technique. Results: Brain water content increased in BDL rats vs SHAM-operated controls (81.91 ± 0.19% vs 81.23 ± 0.20%, p<0.05). BDL rats vs SHAM-operated controls developed an increase in plasma arterial levels of ammonia (91.8 ± 18.4uM vs 41.2 ± 13.2uM, p<0.05), ROS (4.9 fold increase), NO (2.9 fold increase), MDA (41.9 ± 7.4uM vs 9.9 ± 0.6uM, p<0.005), S-nitrosylated proteins and a decrease in catalase activity (1.3 ± 0.5U/ml vs 3.2 ± 1.4U/ml, p<0.05). Centrally, BDL rats vs SHAM-operated controls developed an increase in CSF ammonia (123.5 ± 21.7uM vs 23.3 ± 6.1uM, p<0.05) but did not develop an increase in CSF ROS and NO or in brain MDA and S-nitrosylation detection. Furthermore, catalase activity in the brain was unchanged in BDL vs SHAM-operated controls. Conclusions: Six weeks following BDL, rats developed brain edema. An increase in arterial ammonia was accompanied with an increase in lipid peroxidation, NO, ROS and S-nitrosylation with a decrease in catalase activity. However, a similar increase in ammonia levels in CSF lead to contrary results where no increase in oxidative stress markers was found in brain. Our findings suggest 1) ammonia does not induce oxidative stress in the brain, 2) systemic oxidative stress is related to a decrease in catalase activity and 3) brain edema in BDL rats is associated with systemic, and not central, oxidative stress.

Background: Ammonia plays a major role in the pathogenesis of hepatic encephalopathy however oxidative stress is also believed to be involved. Two lines of evidence lead us to the following aim of our study: 1) neurotoxic levels of ammonia have demonstrated to induce oxidative stress in vitro and 2) systemic oxidative stress is believed to exacerbate the neuropsychological effects of hyperammonemia observed in patients with liver disease. Our aim was to measure oxidative stress markers systemically and centrally, in association with brain edema in rats with cirrhosis. Methods: Rats were sacrificed 6 weeks following bile-ligated induced cirrhosis. Arterial plasma and cerebrospinal fluid (CSF) were collected to measure ammonia (commercially available kit), reactive oxygen species (ROS) (DCFDA-fluorescent technique), nitric oxide (NO) (Griess method) and lipid peroxidation (malondialdehyde, MDA) (commercially available kit). Frontal cortex was dissected to measure antioxidant catalase activity (Amplex Red fluorescent technique), S-nitrosylation of cystein thiols (immunoblotting) and brain water content was determined using the specific gravimetric technique. Results: Brain water content increased in BDL rats vs SHAM-operated controls (81.91 ± 0.19% vs 81.23 ± 0.20%, p<0.05). BDL rats vs SHAM-operated controls developed an increase in plasma arterial levels of ammonia (91.8 ± 18.4uM vs 41.2 ± 13.2uM, p<0.05), ROS (4.9 fold increase), NO (2.9 fold increase), MDA (41.9 ± 7.4uM vs 9.9 ± 0.6uM, p<0.005), S-nitrosylated proteins and a decrease in catalase activity (1.3 ± 0.5U/ml vs 3.2 ± 1.4U/ml, p<0.05). Centrally, BDL rats vs SHAM-operated controls developed an increase in CSF ammonia (123.5 ± 21.7uM vs 23.3 ± 6.1uM, p<0.05) but did not develop an increase in CSF ROS and NO or in brain MDA and S-nitrosylation detection. Furthermore, catalase activity in the brain was unchanged in BDL vs SHAM-operated controls. Conclusions: Six weeks following BDL, rats developed brain edema. An increase in arterial ammonia was accompanied with an increase in lipid peroxidation, NO, ROS and S-nitrosylation with a decrease in catalase activity. However, a similar increase in ammonia levels in CSF lead to contrary results where no increase in oxidative stress markers was found in brain. Our findings suggest 1) ammonia does not induce oxidative stress in the brain, 2) systemic oxidative stress is related to a decrease in catalase activity and 3) brain edema in BDL rats is associated with systemic, and not central, oxidative stress.

Background: The pathogenesis of hepatic encephalopathy (HE) is multifactorial involving gut-derived toxins such as ammonia. Liver disease leads to hyperammonemia and neurotoxic levels of ammonia which have been demonstrated to induce oxidative stress. Therefore a primary treatment target for HE is to decrease ammonia production in the gastrointestinal tract. AST-120 (spherical carbon adsorbent), an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600m2/g works as a sink for neuro- and hepato-toxins present in the gut. In this study, we evaluated the protective effect of AST-120 in attenuating brain edema and the capacity of AST-120 to lower arterial ammonia and oxidative stress in rats with cirrhosis. Methods: Secondary biliary cirrhosis was induced in rats by bile duct ligation (BDL) for 6 weeks. BDL and SHAM-operated rats received AST-120 by gavage in methylcellulose (MC) at a dose of 0.1 or 1g/kg/day for 6 weeks. Control BDL and SHAM-operated groups received MC only. AST and ALT were measured at the end of the treatment period to assess liver function. Ammonia and reactive oxygen species (ROS) were measured in arterial plasma using a commercially available kit and DCFDA-fluorescent technique respectively. Brain water content was measured in the frontal cortex using the specific gravimetric technique. Results: AST-120 was well-tolerated with no deaths in either of the treatment groups. Brain water content increased in BDL vs SHAM-operated rats (81.8 ± 0.1% vs 81.3 ± 0.2%, p<0.05). Both 0.1 and 1g/kg/day AST-120 treatments normalised brain water content in BDL rats. Arterial ammonia increased in the BDL control group vs SHAM-operated controls (175.5 ± 48.1uM vs 105.3 ± 27.3uM, p<0.05) and decreased significantly in BDL 0.1g/kg/day (118.0 ± 6.4uM, p<0.05) and BDL 1g/kg/day (75.4 ± 31.4uM, p<0.05). Circulating levels of ROS were significantly increased in BDL vs SHAM-operated rats (11 fold, p<0.001). AST-120 treatment did not attenuate arterial levels of ROS compared to respective SHAM-operated controls. Liver functions enzymes, AST and ALT, were increased in all BDL rats compared to their respective SHAM-operated controls (p<0.001). Conclusions: AST-120 treatment normalized brain water content and decreased arterial ammonia levels but did not demonstrate an effect on systemic ROS. Long-term treatment with AST-120 is a safe, non-antibiotic alternative demonstrating a significant ammonia-lowering effect, as well as a protective effect on the development of brain edema in rats with chronic liver failure. Additional studies are warranted to evaluate the effects of AST-120 on HE in patients with advanced liver disease.

Background: Liver failure/disease leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy. However, it is believed systemic oxidative/nitrosative stress may exacerbate the neuropsychological effects of hyperammonemia observed in patients with liver disease. The present study aims to investigate the role of oxidative/nitrosative stress in 2 rat models of liver disease/hepatic encephalopathy; 1) portacaval anastomosis (PCA), and 2) bile-duct ligation (BDL). Methods: Rats were sacrificed 4 weeks following PCA and 6 weeks following BDL. Arterial plasma and cerebrospinal fluid (CSF) were collected to measure ammonia, reactive oxygen species (ROS), hydrogen peroxide (H2O2) and nitric oxide (NO). S-nitrosylation of cystein thiols was measured in the frontal cortex and plasma proteins by immunoblotting. Brain water content was measured in the frontal cortex using a specific gravimetric technique. Results: Hyperammonemia developed in both PCA (PCA: 181.0 ± 8.5uM vs sham: 60.5 ± 7.0uM; p< 0.0001) and BDL (BDL: 101.1 ± 11.0uM vs sham: 41.7 ± 9.2uM; p< 0.05) rats with PCA rats being significantly higher compared to BDL rats (p< 0.001). Consequently, ammonia increased in CSF in both PCA (PCA: 159.5 ± 15.8uM vs sham: 32.5 ± 3.7uM; p< 0.0001) and BDL (BDL: 123.5 ± 21.7uM vs sham: 23.3 ± 6.1uM; p< 0.05), but no significant change was observed between PCA and BDL. Only rats with BDL demonstrated an increase in plasma levels of ROS (5.8-fold increase vs sham; p< 0.001), H2O2 (3.2-fold increase vs sham; p< 0.05) and NO (2.9-fold increase vs sham; p< 0.05). This was accompanied by an increase in S-nitrosylation of plasma proteins. An increase in brain water content was observed in rats with BDL (BDL: 81.91 ± 0.19% vs sham: 81.23 ± 0.20, p< 0.05) whereas no significant change in brain water content was found in PCA vs sham-operated control rats. Conclusion: Hyperammonemia together with systemic oxidative stress are associated with brain edema in rats with BDL which is not demonstrated in PCA rats where only hyperammonemia is observed. Our findings suggest systemic oxidative stress is implicated in the pathogenesis of brain edema and its synergistic effect with ammonia may lead to progression of hepatic encephalopathy.

Introduction: L'insuffisance/maladie hépatique mène à l'hyperammonémie, le facteur central dans la pathogénèse de l'encéphalopathie hépatique. Toutefois, le stress oxydatif/nitrosatif peut avoir un rôle important dans l'exacerbation des effets neuropsychologiques de l'hyperammonémie chez les patients atteints de maladies hépatiques. Cette étude a comme objectif l'investigation du rôle du stress oxydatif/nitrosatif dans deux modèles de maladie du foie/encéphalopathie hépatique chez le rat; 1) dérivation portosystémique (PCA), et 2) ligature de la voie biliaire (BDL). Méthodes: Les rats ont été sacrifiés 4 semaines après la PCA ou 6 semaines après la BDL. L'ammoniaque, les espèces réactives d'oxygène (ROS), le H2O2 et l'oxyde nitrique (NO) ont été mesurés dans le plasma (artériel) et l'ammoniaque, les ROS et le NO dans le liquide céphalorachidien (CSF), respectivement par un kit commercial, une technique de fluorescence et la réaction Griess. Le contenu en eau du cerveau a été mesuré dans le cortex frontal par une technique spécifique gravimétrique. Résultats: L'hyperammonémie s'est développée dans les deux groupes, PCA (PCA: 173.7 ± 13.6 uM vs sham: 77.8 ± 11.2 uM; p<0.001) et BDL (BDL: 114.1 ± 19.2 uM vs sham: 33.2 ± 4.7 uM; p<0.05) et les valeurs pour les rats PCA sont significativement plus élevées que celles des BDL (p<0.05). En conséquence, l'ammoniaque est élevée dans le CSF chez les rats PCA (PCA: 146.6 ± 26.0 uM vs sham: 31.5 ± 6.9 uM; p<0.001) et BDL (BDL: 128.4 ± 36.7 uM vs sham: 23.3 ± 6.1 uM; p<0.05). On n'observe pas de différences significatives entre les PCA et BDL. Seulement les rats BDL montrent une augmentation des niveaux plasmatiques de ROS (augmentation de 5.8 fois vs sham; p<0.001) et H2O2 (augmentation de 3.2 fois vs sham; p<0.05). On n'observe pas de différences significatives entre les valeurs des ROS dans le CSF chez les PCA et BDL, comparativement aux groupes contrôles. De plus, on observe une augmentation du contenu en eau du cerveau seulement dans les rats BDL (BDL: 81.52 ± 0.15% vs sham: 80.43 ± 0.21%, p<0.05). Aucun changement significatif dans les niveaux plasmatiques des ROS, H2O2 ou du contenu en eau cérébrale dans les PCA vs les contrôles sham-opérés n'a été trouvé. Conclusion: Le stress oxydatif superposé à l'hyperammonémie entraîne une augmentation du contenu cérébral en eau dans les rats BDL qui n'est pas observée chez les rats PCA, où seulement l'hyperammonémie est présente. Nos résultatss suggèrent que le stress oxydatif systémique est impliqué dans la pathogénèse de l’œdème cérébrale et que son effet synergique avec l'ammoniaque peut mener à la progression de l'encéphalopathie hépatique.

Background: Liver failure/disease leads to hyperammonemia which is central in the pathogenesis of hepatic encephalopathy. However, it is believed systemic oxidative/nitrosative stress may play an important role in exacerbating the neuropsychological effects of hyperammonemia observed in patients with liver disease. The present study aims to investigate the role of oxidative/nitrosative stress in 2 rat models of liver disease/hepatic encephalopathy; 1) portacaval anastomosis (PCA), and 2) bile-duct ligation (BDL). Methods: Rats were sacrificed 4 weeks following PCA and 6 weeks following BDL. Arterial plasma and cerebrospinal fluid (CSF) were collected to measure ammonia, reactive oxygen species (ROS), hydrogen peroxide (H2O2) (only measured in plasma) and nitric oxide (NO) using a commercially available kit, the DCFDA and Amplex Red fluorescent techniques and the Griess reaction respectively. S-nitrosylation of cystein thiols was measured in the frontal cortex and plasma proteins by immunoblotting. Brain water content was measured in the frontal cortex using a specific gravimetric technique. Results: Hyperammonemia developed in both PCA (PCA: 181.0 ± 8.5uM vs sham: 60.5 ± 7.0uM; p<0.0001) and BDL (BDL: 101.1 ± 11.0uM vs sham: 41.7 ± 9.2uM; p<0.05) rats with PCA rats being significantly higher compared to BDL rats (p<0.001). Consequently, ammonia increased in CSF in both PCA (PCA: 159.5 ± 15.8uM vs sham: 32.5 ± 3.7uM; p<0.0001) and BDL (BDL: 123.5 ± 21.7uM vs sham: 23.3 ± 6.1uM; p<0.05), but no significant change was observed between PCA and BDL. Only rats with BDL demonstrated an increase in plasma levels of ROS (5.8-fold increase vs sham; p<0.001), H2O2 (3.2-fold increase vs sham; p<0.05) and NO (2.9-fold increase vs sham; p<0.05). This was accompanied by an increase in S-nitrosylation of plasma proteins. No significant changes in CSF ROS and NO, nor in S-nitrosylation of frontal cortex proteins were found in BDL or PCA compared to their respective control groups. In addition, an increase in brain water content was observed in rats with BDL (BDL: 81.91 ± 0.19% vs sham: 81.23 ± 0.20, p<0.05). No significant change in brain water content was found in PCA rats vs sham-operated controls. Conclusion: Systemic oxidative stress together with hyperammonemia results in an increase in brain water in rats with BDL which is not demonstrated in PCA rats where only hyperammonemia is observed. Our findings suggest systemic oxidative stress is implicated in the pathogenesis of brain edema and its synergistic effect with ammonia may lead to progression of hepatic encephalopathy.

Background: Liver failure/disease leads to hyperammonemia which is central in the pathogenesis of hepatic encephalopathy. However, it is believed systemic oxidative/nitrosative stress may play an important role in exacerbating the neuropsychological effects of hyperammonemia observed in patients with liver disease. The present study aims to investigate the role of oxidative/nitrosative stress in 2 rat models of liver disease/hepatic encephalopathy; 1) portacaval anastomosis (PCA), and 2) bile-duct ligation (BDL). Methods: Rats were sacrificed 4 weeks following PCA or 6 weeks following BDL. Ammonia, reactive oxygen species (ROS), H2O2 and nitric oxide (NO) were measured in plasma (arterial) and ammonia, ROS and NO were measured in cerebrospinal fluid (CSF) using respectively a commercially available kit, a fluorescent technique and the Griess reaction. Brain water was measured in the frontal cortex using a specific gravimetric technique. Results: Hyperammonemia developed in both PCA (PCA: 173.7 ± 13.6 uM vs sham: 77.8 ± 11.2 uM; p<0.001) and BDL (BDL: 114.1 ± 19.2 uM vs sham: 33.2 ± 4.7 uM; p<0.05) rats with PCA rats being significantly higher compared to BDL rats (p<0.05). Consequently, ammonia increased in CSF in both PCA (PCA: 146.6 ± 26.0 uM vs sham: 31.5 ± 6.9 uM; p<0.001) and BDL (BDL: 128.4 ± 36.7 uM vs sham: 23.3 ± 6.1 uM; p<0.05). No significant change was observed between PCA and BDL. Only rats with BDL demonstrated an increase in plasma levels of ROS (5.8-fold increase vs sham; p<0.001) and H2O2 (3.2-fold increase vs sham; p<0.05). No significant change in CSF ROS was found in BDL or PCA compared to their respective control groups. In addition, an increase in brain water content was only observed in rats with BDL (BDL: 81.52 ± 0.15% vs sham: 80.43 ± 0.21%, p<0.05). No significant change in plasma ROS, H2O2 or brain water was found in PCA rats vs sham-operated controls. Conclusion: Oxidative stress in addition to hyperammonemia results in an increase in brain water in rats with BDL which is not in PCA rats where only hyperammonemia is observed. Our findings suggest systemic oxidative stress is implicated in the pathogenesis of brain edema and its synergistic effect with ammonia may lead to progression of hepatic encephalopathy.

Background: Ammonia is central in the pathogenesis of hepatic encephalopathy however it is believed systemic oxidative/nitrosative stress may play an important role in exacerbating the neuropsychological effects of hyperammonemia observed in patients with cirrhosis. Furthermore, it has recently been demonstrated in vitro that pathophysiological concentrations of ammonia induce oxidative/nitrosative stress in brain (cultured astrocytes), however this remains to be evaluated in vivo. The present study aims to investigate the role of oxidative/nitrosative stress in a well characterized hyperammonemic rat model of portacaval anastomosis (PCA). Methods: Rats were sacrificed 4 weeks following PCA or SHAM-operation. Ammonia, nitrate/nitrite, reactive oxygen species and total glutathione were measured in both plasma (arterial) and cerebrospinal fluid. Activities of antioxidant enzymes (catalase, superoxide dismutase and glutathione reductase/peroxidase) were measured in both plasma (arterial) and frontal cortex of the brain. Results: Ammonia concentrations were increased in both plasma (PCA: 173.7 ± 13.58uM vs SHAM: 77.8 ± 11.2uM; p<0.001) and cerebrospinal fluid (PCA: 146.6 ± 26.0uM vs SHAM: 31.5 ± 6.9uM; p<0.001) in PCA rats compared to SHAM operated controls. Furthermore, PCA rats showed a significant increase in catalase (PCA: 3.27 ± 0.03U/ml vs SHAM: 3.10 ± 0.05U/ml; p<0.05) and superoxide dismutase (PCA: 97.30 ± 0.47 vs SHAM: 95.57 ± 0.45 % inhibition; p<0.05) activities, but no significant differences were found in frontal cortex between the two groups. In addition, no significant changes in reactive oxygen species, nitrate/nitrite and total glutathione levels, nor in glutathione reductase and peroxidase activities were found in both plasma and brain tissue of PCA and SHAM rats. Conclusion: Rats with PCA develop hyperammonemia which leads to toxic levels of ammonia in the brain. This in turn does not induce oxidative/nitrosative stress systemically or centrally. Maintenance of systemic antioxidant activity in rats with PCA preserves a balanced redox status and prevents progression of encephalopathy.