GPBAR1 and cholestasis: By acting on the farnesoid X receptor (FXR) and Takeda G protein-coupled receptor 5 (TGR5), bile acids are involved in multiple signaling pathways, including metabolism, fibrosis, and immune homeostasis.4,5 Gut microbiota metabolize bile acids with defined enzymes, and thereby impact the bile acid signalings.4 For example, supplementation of Lactobacillus rhamnosus prevented liver fibrosis in a mouse model of cholestasis through upregulating intestinal FXR signaling.6 In turn, dynamics of bile acids also exert a profound impact on the intestinal microbiome.