Enhanced AMPK phosphorylation contributes to the beneficial effects of Lactobacillus rhamnosus GG supernatant on chronic-alcohol-induced fatty liver disease.

BACKGROUND: We have previously demonstrated that Lactobacillus rhamnosus GG culture supernatant (LGGs) prevents acute-alcohol-exposure-induced hepatic steatosis and injury. The protective effects of LGGs were attributed to the improved intestinal barrier function leading to decreased endotoxemia. The purpose of this study was to determine whether LGGs was effective in protecting against chronic-alcohol-induced hepatic steatosis and injury and to evaluate the underlying mechanisms of LGGs on hepatic lipid metabolism.

METHODS: C57BL/6N mice were fed liquid diet containing 5% alcohol or pair-fed isocaloric maltose dextrin for 4 weeks. LGGs at a dose equivalent to 10(9) CFU/day/mouse was given in the liquid diet. Hepatic steatosis, liver enzymes and hepatic apoptosis were analyzed.

RESULTS: LGGs prevented alcohol-mediated increase in hepatic expression of lipogenic genes, sterol regulatory element binding protein-1 and stearoyl-CoA desaturase-1 and increased the expression of peroxisome proliferator activated receptor-α, peroxisome proliferator-activated receptor gamma coactivator protein-1α and carnitine palmitoyltransferase-1, leading to increased fatty acid β-oxidation. Importantly, chronic alcohol exposure decreased adenosine-monophosphate-activated protein kinase (AMPK) phosphorylation and increased acetyl-CoA carboxylase activity, which were attenuated by LGGs administration. LGGs also decreased Bax expression and increased Bcl-2 expression, which attenuated alcohol-induced hepatic apoptosis. These LGGs-regulated molecular changes resulted in the attenuation of chronic-alcohol-exposure-mediated increase in hepatic fat accumulation and liver injury.

CONCLUSIONS: Probiotic LGG culture supernatant is effective in the prevention of chronic-alcohol-exposure-induced hepatic steatosis and injury. LGGs likely exerts its beneficial effects, at least in part, through modulation of hepatic AMPK activation and Bax/Bcl-2-mediated apoptosis.