Inhibition of miR122a by Lactobacillus rhamnosus GG culture supernatant increases intestinal occludin expression and protects mice from alcoholic liver disease

Alcoholic liver disease (ALD) has a high morbidity and mortality. Chronic alcohol consumption causes disruption of intestinal microflora homeostasis, intestinal tight junction barrier dysfunction, increased endotoxemia, and eventually liver steatosis/steatohepatitis. Probiotic Lactobacillus rhamnosus GG (LGG) and the bacteria-free LGG culture supernatant (LGGs) have been shown to promote intestinal epithelial integrity and protect intestinal barrier function in ALD. However, little is known about how LGGs mechanistically works to increase intestinal tight junction proteins. Here we show that chronic ethanol exposure increased intestinal miR122a expression, which decreased occludin expression leading to increased intestinal permeability. Moreover, LGGs supplementation decreased ethanol-elevated miR122a level and attenuated ethanol-induced liver injury in mice. Similar to the effect of ethanol exposure, overexpression of miR122a in Caco-2 monolayers markedly decreased occludin protein levels. In contrast, inhibition of miR122a increased occludin expression. We conclude that LGGs supplementation functions in intestinal integrity by inhibition of miR122a, leading to occludin restoration in mice exposed to chronic ethanol.