Farzaneh Tamnanloo

Multiple ammonia-induced episodes of hepatic encephalopathy provoke neuronal cell loss in bile-duct ligated rats.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mariana M. Oliveira, Carina Lima, Maggy Lépine, Karine Dubois, Cristina Bosoi, Mélanie Tremblay, Lekha Sleno, Christopher F. Rose.

Constant alcohol consumption exacerbates hepatic encephalopathy and induces neuronal cell loss in rats with chronic liver disease.

Farzaneh Tamnanloo, Xiaoru Chen, Mariana Oliveira, Mélanie Tremblay, Christopher F. Rose.

Background: Hepatic encephalopathy (HE) is a debilitating neurological complication of chronic liver disease. Alcohol is a major etiological factor known to induce liver injury and disease. However, excessive alcohol consumption has been shown to also induce atrophy of the cerebellum and cerebellar degeneration. To date, the role of alcohol in the development of HE remains unclear. Here we examined the effects of constant alcohol consumption on the neurological decline in rats with chronic liver disease induced following bile duct ligation (BDL). Method: 5-week BDL rats and Sham-operated controls (Sham) were used. Starting day 7 after surgery, rats were gavaged twice a day (3 hours apart) with alcohol at a dose of 3g/kg, 5 days per week, for 4 weeks. Motor coordination was assessed using Rotarod every week until week 5. At the end of the model (day 40), anxiety-like behavior was assessed using the open field (OF) and elevated plus maze (EPM). Upon sacrifice, brains were collected, and western blot and immunohistochemical (IHC) analyses were used to investigate the neuronal integrity as well as assess apoptosis and necroptosis pathways in the cerebellum. Results: Alcohol worsened motor coordination performance in weeks 2, 3, 4, and 5 in BDL-alcohol rats (p<0.01 vs respective shams). Anxiety-like behavior significantly increased in BDL-alcohol rats, with an increase in time spent in the closed arms of EPM and a decrease in time spent in the center of the open field (p<0.05 vs respective shams). These impairments were associated with decreased neuronal markers of NeuN and SMI311 (p<0.01 and p<0.05, respectively), increased apoptotic markers of cleaved/pro-Caspase3 and Bax/Bcl2 ratio (p<0.001 and p<0.01 respectively), increased necroptosis markers of pRIP3 and pMLKL (p<0.01 and p<0.001, respectively), decreased total antioxidant capacity (p<0.001) and increased oxidative stress marker of 4-HNE (p<0.05) in the cerebellum of BDL-alcohol rats when compared to respective controls. IHC results confirmed the colocalization of apoptotic marker (cleaved Caspase3) and necroptosis marker (pMLKL) in the granular and Purkinje layer neurons of the cerebellum of BDL-alcohol rats. Conclusion: Constant alcohol consumption exacerbates HE by worsening motor coordination impairment and increasing anxiety in BDL rats. Furthermore, our results show neuronal loss through apoptosis and necroptosis in the cerebellum of BDL-alcohol rats. Additionally, higher levels of oxidative stress marker of 4-HNE and decreased total antioxidant capacity in the cerebellum of BDL-alcohol rats suggest that oxidative stress is the triggering factor of apoptosis and necroptosis pathway leading to neuronal loss/injury. These results demonstrate the adverse effect of constant alcohol consumption on the development of HE and neuronal integrity in chronic liver disease.

L’acide urique comme facteur de risque pour les complications cognitives de la cirrhose du foie : développement et validation d’un nouveau modèle murin.

Sydnée L’Écuyer, Alexandra Matesan, Farzaneh Tamnanloo, Mariana Oliveira, Mélanie Tremblay, Emmanuel Charbonney, Christopher F. Rose.

Exacerbation du déclin neurologique et perte cellulaire neuronale causée par la consommation continuelle d’alcool chez les rats ayant une maladie de foie chronique.

Farzaneh Tamnanloo, Xiaoru Chen, Mélanie Tremblay, Christopher F. Rose.

Oral

Le rôle de la consommation constante d'alcool sur le déclin neurologique et la perte de cellules neuronales chez les rats atteints d'une maladie hépatique chronique.

Farzaneh Tamnanloo, Xiaoru Chen, Mélanie Tremblay, Christopher F. Rose.

Oral

L’acide urique comme facteur de risque pour les complications cognitives de la cirrhose du foie : développement et validation d’un nouveau modèle murin.

Sydnée L’Écuyer, Alexandra Matesan, Farzaneh Tamnanloo, Mariana Oliveira, Mélanie Tremblay, Emmanuel Charbonney, Christopher F. Rose.

Constant alcohol consumption exacerbates neurological decline and causes neuronal cell loss in rats with chronic liver disease.

Farzaneh Tamnanloo, Xiaoru Chen, Mélanie Tremblay, Christopher F. Rose.

Background: Hepatic encephalopathy (HE) is a debilitating neurological complication of chronic liver disease with alcohol being a common etiological factor. However, excessive alcohol consumption has been shown to impact neurological integrity. To date, the influence of alcohol in the development of HE remains unclear. Therefore, we examined the effect of constant alcohol consumption on neurological decline in rats with chronic liver disease induced via bile-duct ligation (BDL). Method: 5-week BDL rats and Sham-operated controls were used. Day 7 after surgery, rats were administered alcohol twice a day (dose of 3g/kg, via gavage) for 4 weeks. Motor coordination (rotarod) and anxiety-like behavior (open field (OF) and elevated plus maze (EPM)) were assessed. Upon sacrifice, brains were collected, and western blot and immunohistochemical (IHC) analyses were used to investigate neuronal integrity in frontal cortex and cerebellum. Results: Alcohol (BDL-alcohol rats) further impaired motor coordination at weeks 2, 3, 4, and 5 compared to SHAM-alcohol (p<0.01). Furthermore, BDL-alcohol rats demonstrated an increase in anxiety-like behavior; increase in time spent in the closed arms of EPM and decrease in time spent in the center of the OF (p<0.05 vs SHAM-alcohol). BDL-alcohol rats demonstrated a decrease in neuronal markers of NeuN and SMI311 (p<0.01 and p<0.05, respectively), an increase in apoptotic markers of cleaved/pro-caspase3 (p<0.001), an increase in necroptosis markers of pRIP3 and pMLKL (p<0.01 and p<0.001, respectively), a decrease in total antioxidant capacity (p<0.001) and an increase in oxidative stress marker of 4-HNE (p<0.05) in the cerebellum (not found in frontal cortex) compared to all groups. IHC results confirmed the colocalization of apoptotic marker (cleaved Caspase3) and necroptosis marker (pMLKL) in the granular and Purkinje layer neurons of the cerebellum of BDL-alcohol rats. Conclusion: Constant alcohol consumption exacerbates HE and leads to neuronal loss via apoptosis and necroptosis in the cerebellum. Additionally, higher levels of oxidative stress marker of 4-HNE and decreased total antioxidant capacity in the cerebellum of BDL-alcohol rats suggest that oxidative stress is a triggering factor leading to neuronal loss/injury. These results demonstrate an adverse effect of constant alcohol consumption on the development of HE and neuronal integrity in chronic liver disease.

Oral

Hyperuricemia as an implicated factor in cognitive impairments in chronic liver disease: developing a new murine model.

Sydnée L’Écuyer, Alexandra Matesan, Farzaneh Tamnanloo, Mariana Oliveira, Mélanie Tremblay, Emmanuel Charbonney, Christopher F. Rose.

Background: Over 40% of patients with liver cirrhosis also suffer from cognitive impairments, mainly from hepatic encephalopathy (HE). This reversible and episodic syndrome leads to gross disorientation, asterixis, memory impairments, and death and is associated with an increase in blood ammonia. However, some patients with cirrhosis present with cognitive alterations in absence of increased ammonia circulation. This justifies investigating other factors that may induce further cerebral lesions than what is seen in HE. With this project, we focus on the role of uric acid (UA) and hyperuricemia in inducing cognitive impairments in cirrhosis. Hyperuricemia is associated with metabolic syndrome and chronic alcohol consumption which are known precipitating factors of CLD. Furthermore, uric acid (UA) has been reported to be involved in the induction of neuroinflammation and cell loss by apoptosis and pyroptosis, leading to anxiety-like behavior and memory impairment. This project uses a joint murine model of chronic liver disease and hyperuricemia to investigate behavioral alterations and cerebral lesions. Method: To induce liver cirrhosis we used the well-characterized model of bile-duct ligation (BDL) knowing that these animals also develop symptoms of ammonia-related HE. Fifty-two male Sprague-Dawley rats (200-240 g) were randomly assigned to a control (SHAM) or a BDL surgery. To induce hyperuricemia, half of the animals were fed a high uric acid diet (HUAD) (3% uric acid), dividing our rats into 4 groups: (1) SHAM+regular diet (RD), (2) SHAM+HUAD, (3) BDL+RD and (4) BDL+HUAD. Plasma UA measurements were made on days 0, 7, 14, 21, and 28. Behavior tests were conducted to measure anxiety (open-field test and elevated plus-maze) and short and long-term memory (novel-object recognition) at days 14 and 28. At day 33, the rats were sacrificed, their brains collected, and the frontal cortex, hippocampus, and amygdala were isolated to assess cell death by measuring caspase-3 (apoptosis) and caspase-1 (pyroptosis) activity. Result(s): HUAD significantly increased circulating UA in BDL rats. This was associated with a significant decrease in short-term memory without changes in anxiety-like behavior for HUAD rats compared to their RD counterparts in both SHAMs and BDLs. For long-term memory, BDLs were shown to be significantly impaired compared to SHAMs. A significantly higher degree of impairment was seen in BDL+HUAD rats compared to BDL+RD. Cell death (apoptosis and pyroptosis) was then evaluated in the limbic system to explain some of the behavioral changes. In the frontal cortex, we can see a significant increase of caspase-3 activity in the SHAM+HUAD animals when compared to the SHAM+RD rats and no changes for caspase-1 activity. In the amygdala, we see a significant increase of caspase-3 activity in the BDL+HUAD rats when compared to all three other groups and a significant increase of caspase-1 in the SHAM+HUAD and BDL+HUAD groups when compared to their RD counterparts. In the hippocampus, we see a significant increase of caspase-3 activity for the SHAM+HUAD and BDL+HUAD groups when compared to their RD counterparts. We also detect a significant increase of caspase-1 activity in both HUAD groups. Conclusion(s): In SHAM rats, diet-induced hyperuricemia shows a significant increase in circulating uric acid concentration as well as short-term memory loss associated with apoptosis (caspase-3 activity) in the frontal cortex and the hippocampus. In BDL rats, hyperuricemia induces long-term memory impairments and apoptosis in the frontal cortex as well as pyroptosis in the hippocampus. The results from this study show the merit of further investigating the role of hyperuricemia in cognitive impairment in the context of liver cirrhosis.

Constant alcohol consumption exacerbates neurological decline and causesneuronal cell loss in rats with chronic liver disease

Farzaneh Tamnanloo, Xiaoru Chen, Mélanie Tremblay, Christopher F. Rose.

Background: Hepatic encephalopathy (HE) is a debilitating neurological complication of chronic liver disease with alcohol being a common etiological factor. However, excessive alcohol consumption has been shown to impact neurological integrity. To date, the influence of alcohol in the development of HE remains unclear. Therefore, we examined the effect of constant alcohol consumption on neurological decline in rats with chronic liver disease induced via bile-duct ligation (BDL). Method: 5-week BDL rats and Sham-operated controls were used. Day 7 after surgery, rats were administered alcohol twice a day (dose of 3g/kg, via gavage) for 4 weeks. Motor coordination (rotarod) and anxiety-like behavior (open field (OF) and elevated plus maze (EPM)) were assessed. Upon sacrifice, brains were collected, and western blot and immunohistochemical (IHC) analyses were used to investigate neuronal integrity in frontal cortex and cerebellum. Results: Alcohol (BDL-alcohol rats) further impaired motor coordination at weeks 2, 3, 4, and 5 compared to SHAM-alcohol (p<0.01). Furthermore, BDL-alcohol rats demonstrated an increase in anxiety-like behavior; increase in time spent in the closed arms of EPM and decrease in time spent in the center of the OF (p<0.05 vs SHAM-alcohol). BDL-alcohol rats demonstrated a decrease in neuronal markers of NeuN and SMI311 (p<0.01 and p<0.05, respectively), an increase in apoptotic markers of cleaved/pro-caspase3 (p<0.001), an increase in necroptosis markers of pRIP3 and pMLKL (p<0.01 and p<0.001, respectively), a decrease in total antioxidant capacity (p<0.001) and an increase in oxidative stress marker of 4-HNE (p<0.05) in the cerebellum (not found in frontal cortex) compared to all groups. IHC results confirmed the colocalization of apoptotic marker (cleaved Caspase3) and necroptosis marker (pMLKL) in the granular and Purkinje layer neurons of the cerebellum of BDL-alcohol rats. Conclusion: Constant alcohol consumption exacerbates HE and leads to neuronal loss via apoptosis and necroptosis in the cerebellum. Additionally, higher levels of oxidative stress marker of 4-HNE and decreased total antioxidant capacity in the cerebellum of BDL-alcohol rats suggest that oxidative stress is a triggering factor leading to neuronal loss/injury. These results demonstrate an adverse effect of constant alcohol consumption on the development of HE and neuronal integrity in chronic liver disease.

Oral

Constant alcohol consumption exacerbates hepatic encephalopathy inducing neuronal cell loss in rats with chronic liver disease.

Farzaneh Tamnanloo, Mélanie Tremblay, Christopher F. Rose.

Background: Hepatic encephalopathy (HE) is a complex neuropsychiatric syndrome arising from chronic liver disease (CLD). HE manifests with symptoms such as poor memory, impairment in motor coordination, lethargy and coma. The gut microbiota has been shown to influence neurological functions via various mediators such as cytokines or bacterial metabolites, many studies have demonstrated the gut-brain axis is altered in liver disease. Faecal matter transplantation (FMT) in patients with cirrhosis has revealed beneficial effects yet many limitations of these studies render the results inconclusive. Purpose: The aim of this study is to explore the impact of FMT on gut microbiota and the beneficial effects on neuro behaviour in bile-duct ligated (BDL) rats. Method: Male Sprague-Dawley rats were randomly assigned to one of three groups; SHAM, BDL-VEH (vehicle) and BDLFMT (who received FMT daily from pooled faeces from SHAM rats). After five weeks, behaviour tests were performed to evaluate short- and long-term memory (Novel Object Recognition), anxiety (Open Field and Elevated Plus Maze) and motor coordination (Rotarod). Plasmatic parameters such as cytokines, short chain fatty acids (SCFA) and liver impairment markers were measured by ELISA, LC-MS/MS and using Cobas respectively. Finally, faeces were collected for bacterial sequencing and SCFA analysis. Result(s): FMT did not alter degree of liver disease in BDL rats. BDL-VEH developed a loss of short/long term memory and motor coordination compared to SHAM rats. However, alterations in neurological dysfunction were prevented in the BDL-FMT group. FMT did not impact microbiota α-diversity in BDL rats and β-diversity of microbiota was significantly different between all groups. The genera Bifidobacterium, Lactobacillus and Akkermansia significantly increased in both BDL groups, while Provotellaceae UCO-001 significantly increased only in SHAM and BDL-FMT rats and Clostridium Senso Stricto 1 significantly increased only in BDL-VEH compared to SHAMs. Finally, Rombustia was only present in SHAM. Plasma pro-inflammatory cytokines (TNF-α & IL-1) increase in both BDL groups compared to the control group and no difference for the anti-inflammatory cytokine IL-10 was noted. Analysis of short-chain fatty acids in faeces and plasma showed a variation in propionate and butyrate between both BDL groups. Plasma propionate significantly positively correlated with behavioural results.Conclusion(s): Our results demonstrate that FMT leads to improvement in memory and motor coordination in BDL rats. The microbiota profile was different between BDL-VEH and SHAM, and FMT lead to further alterations on microbiota. The fact that FMT did not normalize microbiota profile compared to SHAM, suggests BDL-FMT leads to a novel specific microbiota profile which in turn protects the brain. The protective effect of plasma propionate needs to be further explored to define its impact on the brain and possible therapeutic application.

Hyperuricemia as a risk factor for cognitive impairments in chronic liver disease: developing a new murine model.

Sydnée L'Écuyer, Alexandra Matesan, Farzaneh Tamnanloo, Mariana Oliveira, Mélanie Tremblay, Emmanuel Charbonney, Christopher F. Rose.

Background: Hepatic encephalopathy (HE) is a debilitating complication of cirrhosis that affects over 40% of chronic liver disease (CLD) patients, leading to gross disorientation, asterixis, memory impairments, and death. An increase in blood ammonia has been coined the major factor in the pathogenesis of HE. However, the severity of symptoms does not always correlate with blood ammonia concentrations. This implies other factors may be involved. Hyperuricemia is associated with metabolic syndrome and chronic alcohol consumption which are known precipitating factors of CLD. Furthermore, uric acid (UA) has been reported to be involved in the induction of neuroinflammation and cell loss by apoptosis and pyroptosis, leading to anxiety-like behavior and memory impairment. Purpose: This study investigates the impact of hyperuricemia on cognitive impairment in a rat model of chronic liver disease. Method: We used the bile-duct ligation (BDL) model; a well-characterized rat model of chronic liver disease and HE. Fifty-two male Sprague-Dawley rats (200-240 g) were randomly assigned to a control (SHAM) or a BDL surgery. To induce hyperuricemia, half of the animals were fed a high uric acid diet (HUAD) (3% uric acid), dividing our rats into 4 groups: (1) SHAM+regular diet (RD), (2) SHAM+HUAD, (3) BDL+RD and (4) BDL+HUAD. During 5 weeks, weekly plasma UA measurements were made and different behavior tests were conducted (anxiety (open-field) and short and long-term memory (novel-object recognition)) during the 5th week. At the end of week 5, rats were sacrificed, their brains collected, and the frontal cortex, hippocampus, and amygdala were isolated to assess cell death (caspase-3 (apoptosis) and caspase-1 (pyroptosis) activity). Result(s): HUAD significantly increased circulating UA in both SHAM and BDL rats. This was associated with a significant decrease in short-term memory without changes in anxiety-like behaviour for HUAD rats compared to their RD counterparts in both SHAMs and BDLs. For long-term memory, BDLs were shown to be significantly impaired compared to SHAMs. A significantly higher degree of impairment was seen in BDL+HUAD rats compared to BDL+RD. Cell death (apoptosis and pyroptosis) was then evaluated in the limbic system to explain some of the behavioral changes. In the frontal cortex, increased caspase-3 activity was measured in both SHAM+HUAD and BDL+HUAD rats in comparison to RD animals. In the hippocampus, caspase-1 activity was significantly increased in the BDL+HUAD rats compared to the BDL+RD rats and SHAM groups. In the amygdala, no significant changes in caspase activity were detected. Conclusion(s): In SHAM rats, diet-induced hyperuricemia shows a significant increase in circulating uric acid concentration as well as short-term memory loss associated with apoptosis (caspase-3 activity) in the frontal cortex. In BDL rats, hyperuricemia induces long-term memory impairments and apoptosis in the frontal cortex as well as pyroptosis in the hippocampus. The results from this study show the merit of further investigating the role of uric acid in HE.

Les effets de l’alcool éthylique sur le cervelet des rats cirrhotiques.

Samia Cherkaoui, Farzaneh Tamnanloo, Xiaoru Chen, Mélanie Tremblay, Christopher F. Rose.

Repeated ammonia-induced episodes of hepatic encephalopathy leads to neuronal cell loss in rats with chronic liver disease.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

Background: Hepatic encephalopathy (HE) is a major complication of chronic liver disease (CLD). Defined as a metabolic disorder, HE should resolve following liver transplantation (LT). However, persisting neurological complications have been reported in up to 47% of LT recipients. Retrospective studies have demonstrated an association between a history of HE episodes and neu-rological deficits post-LT. Our aim was to evaluate the impact of multiple episodes (induced by ammonia) on neurological status, integrity and injury in rats with CLD. Methods: 5-week bile-duct ligation (BDL) rats were in-jected (ip) with ammonium acetate (BDL-Ammonia), pre-cipitating an overt episode of HE (loss of righting reflex). Episodes of HE were induced every 4 days from week 3 post-BDL surgery (total; 4 episodes). Sham rats were also injected with a similar dose of ammonia (Sham-Ammonia) and respective controls were injected with sa-line. Three days after the last episode, long-term mem-ory (LTM) was assessed. Upon sacrifice, plasma and brains were collected for oxidative stress measurements and western blot analysis for NeuN and SMI311 (neuro-nal markers), caspase-3 and Bax/Bcl2 ratio (markers of apoptosis), GFAP (astrocyte marker) and 4-HNE (marker of oxidative stress) in frontal cortex, cerebellum and hip-pocampus. Results: LTM was found to be impaired in both BDL-Saline and BDL-Ammonia groups vs respec-tive controls. However, LTM impairment was further ag-gravated in BDL-Ammonia rats. In BDL-Ammonia, higher protein levels of GFAP and apoptotic markers were found in the hippocampus, whereas NeuN and SMI311 levels were reduced compared to all other experimental groups. BDL-Ammonia rats showed increased levels of plasma oxidative stress compared to respective Sham and BDL rats. Decreased levels of total antioxidant capacity as well as increased 4-HNE were found solely in the hip-pocampus (not frontal cortex or cerebellum) of the BDL-Ammonia group compared to controls. Conclusion:Multiple episodes of overt HE leads to a worsening of neurological impairment in BDL rats. LTM impairment in the BDL-Ammonia rats was associated with increased oxidative stress, apoptotic markers and decreased neu-ronal markers in the hippocampus, supporting neuronal injury/loss. Elevated levels of GFAP in the hippocampus insinuate gliosis, possibly a result of neuronal loss. These results suggest that repeated HE episodes may cause permanent cell damage which will less likely be revers-ible following LT.

Des épisodes d’encéphalopathie hépatique induits par l’ammoniaque mènent à des dommages cellulaires neuronaux chez les rats avec ligation de voie biliaire.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

Multiple hyperammonemia-induced episodes of HE leads to neuronal loss in rats with chronic liver disease.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

Multiple hyperammonemia-induced episodes of HE leads to neuronal loss in rats with chronic liver disease.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

Background: Hepatic encephalopathy (HE) is a major complication of chronic liver disease (CLD). HE is defined as a metabolic syndrome and therefore should resolve following liver transplantation (LT). However, persisting neurological complications and poor quality of life have been reported in up to 47% of LT recipients. Several retrospective studies have demonstrated an association between a history of HE episodes and neurological deficits following LT. However, the impact of HE episodes on the brain remains unknown. Purpose: Our aim was to evaluate the impact of multiple episodes (induced by ammonia) on neurological status, integrity and brain injury in cirrhotic rats. Method: 5-week bile-duct ligation (BDL) rats and Sham-operated controls (Sham) were used. BDL rats were injected (ip) with ammonium acetate (BDL-Ammonia), precipitating an overt episode of HE (pre-coma; loss of righting reflex) every 4 days from week 3 post-BDL surgery (total; 4 episodes). Sham rats were also injected with ammonia (Sham-Ammonia) and BDL and Sham rats were injected with saline as controls. Three days after the last episode, both short- and long-term memory (LTM) were assessed. Upon sacrifice, plasma and brains were collected for oxidative stress measurements and western blot analysis for Neuronal nuclei (NeuN and SMI311), caspase-3 (apoptotic marker), Bax/Bcl2 ratio (apoptotic marker), GFAP (astrocyte marker) and 4-HNE (oxidative stress marker) in frontal cortex, cerebellum and hippocampus. Result(s): LTM was found to be impaired in both BDL-Saline and BDL-Ammonia groups vs respective Sham controls. However, LTM impairment was further aggravated in BDL-Ammonia rats. In BDL-Ammonia, higher protein levels of GFAP and apoptotic markers were found in the hippocampus, whereas NeuN and SMI311 levels were reduced compared to all other experimental groups. BDL-Ammonia rats showed increased levels of plasma oxidative stress compared to respective Sham and BDL rats. Decreased levels of total antioxidant capacity and increased 4-HNE (oxidative stress marker) were found in the hippocampus (not in frontal cortex or cerebellum) of the BDL-Ammonia group compared to respective sham and BDL rats. Conclusion(s): Multiple episodes of overt HE lead to a worsening of the neurological impairments in BDL rats. LTM impairment in the BDL-Ammonia rats was associated with increased oxidative stress, apoptotic markers (caspase-3, Bax/Bcl2) and decreased neuronal markers (NeuN, SMI311) in the hippocampus, suggesting neuronal injury/loss. Elevated levels of GFAP in the hippocampus insinuate gliosis, possibly a result of neuronal loss. These results suggest that cumulative HE episodes may cause permanent cell damage and, therefore, will less likely reversible following LT. The impact of HE on neurological outcomes following LT merits further investigation.

Ammonia-induced episodic HE leads to neuronal cell injury in bile-duct ligated rats

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

Episodic hepatic encephalopathy induces neuronal cell injury in rats with chronic liver disease

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

Background: Hepatic encephalo¬pathy (HE) is a neuro¬psychiatric syn¬drome and it is understood to be reversible following liver transplantation (LT). However, up to 47% of LT patients have been documented to have persisting neurological complications which is believed to be associated with a history of HE pre-LT. We hypo¬thesize that episodes of HE will accelerate neuro¬logical deterioration. Our goal was to evalu¬ate the impact of cumulative HE episodes (ammonia induced) on neuro¬logical status and brain injury in rats with chronic liver disease (CLD). Methods: Five-week bile-duct ligation (BDL) rats and Sham-operated controls were grouped into episodic and non-episodic groups. Episodes of HE were induced every 4 days starting the week 3 post-BDL following a reversible injection of ammonium acetate in which BDL rats fell into pre-coma (loss of righting reflex) for 20-30min. Three days following the last injection, neurobehavior was assessed. Upon sacrifice, plasma ammonia was measured, and brains were collected for western blot and immunofluorescence analysis; neuronal markers including NeuN and SMI311, astrocytic marker; GFAP and apoptotic markers such as cleaved caspase-3 and Bax and Bcl2 were measured to evaluate neurological integrity. Results: BDL rats, and not Sham rats, injected with ammonia developed overt HE. Long-term memory (LTM) was impaired in both non- and episodic BDL groups vs respective controls. However, LTM impairment was further aggravated in episodic BDL rats. Protein expression levels of GFAP, cleaved caspase-3 and Bax/Bcl2 ratio were significantly increased, whereas NeuN and SMI311 were significantly decreased in hippocampus of episodic BDL rats vs non-episodic BDL rats. Presence of cleaved caspase-3 in neuronal layer of CA1 area of hippocampus was confirmed with immunofluorescence imaging. Blood ammonia levels were found to be higher in episodic vs non-episodic BDL rats. Conclusion: Episodes of overt HE exasperate neurological impairment in BDL rats. LTM impairment was associated with an increase in apoptotic markers, decrease in neuronal markers and presence of cleaved caspase-3 in neuronal layer of CA1 area of hippocampus, suggesting neuronal injury/loss. Elevated levels of GFAP (astrocytic marker) in the hippocampus insinuates gliosis, possibly as a consequence of neuronal loss. These results suggest that multiple episodes of HE may cause permanent cell damage, leading to therefore irreversible and persisting neurological complications post-LT.

OpenAccess

Hepatic Encephalopathy: From Metabolic to Neurodegenerative.

Rafael Ochoa-Sanchez, Farzaneh Tamnanloo, Christopher F. Rose.

Ammonia-induced episodic HE leads to neuronal cell injury in bile-duct ligated rats.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

Ammonia-induced episodic HE leads to neuronal cell injury in bile-duct ligated rats.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

La barrière hémato-encéphalique lors d'encéphalopathie hépatique épisodique.

Mihai Alexandru Popovici, Farzaneh Tamnanloo, Mélanie Tremblay, Christopher F. Rose.

Repeated hyperammonemic insults leads to irreversible brain injury in bile-duct ligated rats.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

Background: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD). Defined as a metabolic disorder, HE is understood to be reversible following liver transplantation (LT). However, up to 47% of LT patients have been documented to have persisting neurological complications. Retrospective studies have revealed that patients with a history of overt HE are associated with a poor neurological outcome post-LT. However, the impact of HE episodes on neuro¬logical in¬tegrity is unknown. We hypothesize that episodes of HE will accelerate and/or exasperate neurological deterioration. Purpose: Our goal was to characterize an animal model of episodic HE and to evaluate the impact of cumulative episodes induced by hyperammonemia on neurological status and brain injury in cirrhotic rats. Method: For animal model of CLD and HE, 5-week bile-duct ligation (BDL) rats, and Sham-operated controls were used. Rats, both Sham and BDL, were divided in two groups, episodic and non-episodic. Injection (ip) of ammonium acetate was used to induce episodes of overt HE (pre-coma; loss of righting reflex) every 4 days starting at 3-weeks post-BDL surgery (total 4 episodes). Saline was injected as vehicle for non-episodic group. Three days following the last episode of HE, neurological status was assessed. Upon sacrifice, plasma ammonia was measured, and brains were collected for western blot analysis; Neuronal nuclei (NeuN), caspase-3 (apoptotic marker) and GFAP (astrocyte marker) were measured to evaluate neurological integrity. Results: BDL rats (vs Sham) following ammonia insult developed overt HE (loss of righting reflex). Long-term memory (LTM) was impaired in both non-episodic and episodic BDL groups vs respective controls. However, LTM impairment was further aggravated in episodic BDL rats. Both GFAP and cleaved caspase-3 protein expression were significantly increased, whereas NeuN was significantly decreased in hippocampus of episodic BDL rats vs non-episodic BDL rats. Blood ammonia levels were found to be higher in episodic vs non-episodic BDL rats. Conclusion: HE episodes exasperate neurological impairments in BDL rats. LTM impairment was associated with an increase in the apoptotic marker (caspase-3) and a decrease in neuronal marker (NeuN) in the hippocampus, suggesting neuronal injury/loss. Elevated levels of GFAP in the hippocampus insinuates gliosis as a consequence of neuronal loss. These results suggest that multiple episodes of HE may cause permanent cell damage and therefore will less likely be reversible following LT justifying persisting neurological complications post-LT.

The attenuation of hyperammonemia by genetically engineered E. coli Nissle counters memory deficits in an experimental model of cirrhosis and hepatic encephalopathy.

Rafael Ochoa-Sanchez, Alexis Monnet, Farzaneh Tamnanloo, Mariana M. Oliveira, Mélanie Tremblay, Mylene Perreault, Bill Querbes, Caroline Kurtz, Christopher F. Rose.

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.

Developing a New Animal Model of Episodic Hepatic Encephalopathy.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

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.

Obesity accelerates and exacerbates neurological impairments associated to hepatic encephalopathy in chronic liver disease.

Alexis Monnet, Farzaneh Tamnanloo, Mariana M. Oliveira, Mylene Perreault, Bill Querbes, Caroline B. Kurtz, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

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.

Genetically Engineered E. coli Nissle attenuates hyperammonemia and improves memory in an experimental model of cirrhosis and hepatic encephalopathy.

Rafael Ochoa-Sanchez, Alexis Monnet, Farzaneh Tamnanloo, Mariana M. Oliveira, Mélanie Tremblay, Mylene Perreault, Bill Querbes, Caroline B. Kurtz, Christopher F. Rose.

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.

Characterization of a novel animal model of episodic hepatic encephalopathy.

Farzaneh Tamnanloo, Rafael Ochoa-Sanchez, Mélanie Tremblay, Christopher F. Rose.

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.

Farzaneh Tamnanloo

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