EASL2017, Nutrition UdM and DéfiCRCHUM

Tout un weekend!

Des prix de présentations, des posters au EASL 2017 et des coureurs lors du défiCRCHUM!

Toute une fin de semaine pour les membres du labo!; Rafael et Christopher étaient présents à Amsterdam pour le congrès de l'European Association of the Study of the Liver 2017. Deux posters y ont été présentés.

Parallèlement, Cassandra et Annie présentaient respectivement un oral et un poster lors de la journée de la recherche du département de nutrition de l'Université de Montréal. Toutes deux ont gagné le premier prix de leur catégorie! Félicitations!

Samedi avait lieu le défiCRCHUM au parc Jean-Drapeau. Gregory a couru 10km et Annie 5km pour amasser des fonds pour la recherche. Bravo à tous les deux!

Publications connexes

Glutamine synthetase in endothelial cells of the blood-brain barrier: less but not insignificant?

Christopher F. *Rose, Mariana Oliveira, Mélanie Tremblay, Christopher F. Rose.

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

New animal model of obesity and chronic liver disease to provide insights on non-alcoholic liver disease-induced hepatic encephalopathy.

Rafael Ochoa-Sanchez, Mélanie Tremblay, Marc-André Clément, Marcos Ocana-Sanchez, Christopher F. Rose.

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.

Oral

Impact de l'état nutritionnel sur l'encéphalopathie hépatique et la qualité de vie chez les patients atteints de maladie chronique du foie: résultats préliminaires d'une étude prospective.

Cassandra Picinbono-Larose, Annie Lamoussenerie, Mélanie Tremblay, Catherine Vincent, Geneviève Huard, Christopher Rose, Chantal Bémeur.

Comparaison d’outils d’évaluation nutritionnelle lors de cirrhose.

Annie Lamoussenerie, Cassandra Picinbono-Larose, Mélanie Tremblay, Thierry Cresson, Catherine Vincent, Geneviève Huard, Christopher F. Rose, Chantal Bémeur.