Microbial changes resulting from VSG attenuate MASLD by modulating bile acid metabolism and the intestinal FXR-FGF19 axis

Fecal transplantation from bariatric surgery patients and mice to germ-free mice has shown that the gut microbiota may contribute to metabolic benefits after bariatric surgery. However, the mechanisms by which the gut microbiota contributes to metabolic benefits after bariatric surgery require further investigation. To address this gap, we investigated the effects of the vertical sleeve gastrectomy (VSG) gut microbiota on metabolic dysfunction-associated steatotic liver disease (MASLD) <i>in vivo</i> and elucidated its underlying mechanisms. Our study demonstrated that VSG significantly improved the gut microbiota, especially by increasing bile salt hydrolase (BSH) activity, in MASLD rats. Increased BSH activity significantly increased the proportion of FXR-agonistic bile acids and further activated the intestinal FXR-FGF19 axis, thereby improving MASLD. These findings explored the key roles and mechanisms of the gut microbiota in the metabolic benefits of VSG, offering new microbiome-based treatment strategies.