Bile acid–microbiota crosstalk in gastrointestinal inflammation and carcinogenesis

Bile acids are critical components of the gastrointestinal tract that link the gut microbiota to hepatic and intestinal metabolism and therefore influence gastrointestinal motility, intestinal permeability and carcinogenesisThe gut microbiota regulates bile acid production and signalling via the biotransformation of intestinal bile acids to unconjugated and secondary forms that readily activate bile acid receptorsBile acids are ligands for the G protein-coupled bile acid receptor 1 (TGR5) and for the nuclear hormone receptor farnesoid X receptor (FXR)The profiles of bile acids and gut microbiota influence each other; bile acids can modulate microbiota composition, which in turn regulates the size and composition of the bile acid poolDisruption of bile acid–microbiota crosstalk promotes inflammation and a gastrointestinal disease phenotype, which can contribute to the development of gastrointestinal cancers, including colorectal cancer and hepatocellular carcinomaThe modulation of gut microbiota and bile acid profiles holds promise as a novel therapeutic approach for the treatment of gastrointestinal cancers and represents the next frontier for gastrointestinal cancer research