Bile acid-gut microbiota metabolic axis

The bile acid-gut microbiota metabolic axis is a complex signaling network involving the transformation of host-derived primary bile acids into secondary bile acids by intestinal bacteria (Wahlström et al., 2016). Primary bile acids like cholic acid and chenodeoxycholic acid are synthesized in the liver and conjugated before secretion into the gut, where microbiota enzymes such as bile salt hydrolases (BSH) and 7α-dehydroxylases convert them into secondary bile acids like deoxycholic acid and lithocholic acid (Ridlon et al., 2006). These bile acids act as ligands for host receptors, including the farnesoid X receptor (FXR) and the G protein-coupled bile acid receptor 1 (TGR5), which regulate cholesterol, glucose, and energy metabolism (Fiorucci et al., 2019). Dysregulation of this axis is associated with metabolic and gastrointestinal disorders, including non-alcoholic fatty liver disease (NAFLD) and inflammatory bowel disease (IBD) (Long et al., 2017). Therapeutic strategies include the use of FXR agonists like obeticholic acid, bile acid sequestrants, and inhibitors of the apical sodium-dependent bile acid transporter (ASBT) to modulate bile acid pool composition and signaling (Trauner et al., 2017).

Other names

Bile acid-gut microbiota axisGut-liver-bile acid axisMicrobial bile acid metabolismSecondary bile acid synthesis pathway

Activation of farnesoid X receptor (FXR) and G protein-coupled bile acid receptor 1 (TGR5), inhibition of apical sodium-dependent bile acid transporter (ASBT), and sequestration of bile acids in the intestinal lumen.