A small intestinal bile acid modulates the gut microbiome to improve host metabolic phenotypes following bariatric surgery

Bariatric surgical procedures such as sleeve gastrectomy (SG) provide effective type 2 diabetes remission in human patients. Previous work demonstrated that gastrointestinal levels of the bacterial metabolite lithocholic acid (LCA) are decreased after SG in mice and humans. Here, we show that LCA worsens glucose tolerance and impairs whole body metabolism. We also show that taurodeoxycholic acid (TDCA), which was the only bile acid whose concentration was increased in the murine small intestine post-SG, suppresses the bacterial bile acid-inducible (bai) operon and production of LCA both in vitro and in vivo. Treatment of diet-induced obese (DIO) mice with TDCA reduces LCA levels and leads to microbiome-dependent improvements in host glucose handling. Moreover, TDCA abundance is decreased in small intestinal tissue from T2D patients. This work has revealed that TDCA is an endogenous inhibitor of LCA production and suggests that TDCA may contribute to the glucoregulatory effects of bariatric surgery.