Protein supplementation differentially alters gut microbiota and associated liver injury recovery in mouse model of alcohol-related liver disease

Abstract

Background

Patients with Alcohol-related Liver Disease (ALD) are advised increased protein supplementation. These nutrients are also available to gut microbiota. We evaluated the effects of protein supplementation from two sources, soya (veg) or egg, on gut microbiota modulation and ALD remission.

Methods

ALD was induced in mice using the Lieber-DeCarli diet and incremental ethanol + thioacetamide (150 mg/kg body-weight,i.p.) twice-a-week. After 8wks, mice were fed standard (std.), egg (ovalbumin) or veg diet (20 % increase protein) for 7days. Biochemical parameters, hepatic proteome and gut microbiota composition were analyzed and correlated to capture liver and intestinal recovery.

Results

Veg-diet decreased hepatic steatosis and fibrosis compared with std diet (83.3 %, p = 0.001 and 75 %, p = 0.01, respectively) or egg-diet (66.6 %, p = 0.03 and 25 %, p = 0.04, respectively). ALT and AST levels reduced by 40 % (p = 0.04) and 27.3 % (p = 0.04), respectively in veg diet compared to egg diet. Veg-diet increased intestinal claudin-3 (61 %, p = 0.02) and occludin (80 %, p = 0.001) compared to egg-diet. Plasma endotoxin levels in veg were reduced by 64 % and 32 % compared to std. (p = 0.04) or egg (p = 0.06). Veg-diet increased beneficial taxa, Lachnospiraceae UCG-006 (8.06-folds, p = 1.64E-25), Prevotellaceae NK3B31 (9.96-folds, p = 1.58E-36), Kurthia (8.11-folds, p = 3.98E-16) and Akkermansia (5.9-folds, p = 5.01E-75), while decreasing pathogenic Roseburia (−3.28-folds, p = 1.60E-06), Klebsiella (−5.7-folds, p = 1.55E-06), Staphylococcus (−5.3-folds, p = 1.62E-12). Hepatic proteome showed an increase in pyruvate, cysteine, methionine metabolism, bile acid biosynthesis, and glycolysis.

Conclusion

Alteration in protein alone can affect variable outcomes in ALD, with protein from vegetable sources resulting in enhanced improvement in the gut–liver axis. Vegetable protein-supplemented diet enhances fatty acid beta oxidation and energy metabolism accompanied by improvement in gut-dysbiosis and ALD associated hepatic injury.