Dietary fiber alleviates alcoholic liver injury via Bacteroides acidifaciens and subsequent ammonia detoxification.

The gut microbiota and diet-induced changes in microbiome composition have been linked to various liver diseases, although the specific microbes and mechanisms remain understudied. Alcohol-related liver disease (ALD) is one such disease with limited therapeutic options due to its complex pathogenesis. We demonstrate that a diet rich in soluble dietary fiber increases the abundance of Bacteroides acidifaciens (B. acidifaciens) and alleviates alcohol-induced liver injury in mice. B. acidifaciens treatment alone ameliorates liver injury through a bile salt hydrolase that generates unconjugated bile acids to activate intestinal farnesoid X receptor (FXR) and its downstream target, fibroblast growth factor-15 (FGF15). FGF15 promotes hepatocyte expression of ornithine aminotransferase (OAT), which facilitates the metabolism of accumulated ornithine in the liver into glutamate, thereby providing sufficient glutamate for ammonia detoxification via the glutamine synthesis pathway. Collectively, these findings uncover a potential therapeutic strategy for ALD involving dietary fiber supplementation and B. acidifaciens.