The Gut–Liver Axis in Liver Inflammation, Fibrosis, and Cancer

Abstract

The liver is connected directly to the intestinal tract by the portal vein. In recent years, it has been clarified that intestinal factors play a very important role in the onset and progression of liver diseases through enterohepatic circulation. In increased intestinal permeability caused by various stresses, gut-derived LPS or LTA induce inflammatory signals via liver TLRs and promote liver fibrosis, cirrhosis and liver cancer. Moreover, although bile acids regulate metabolism-related gene expression through FXR or TGR5 signals and maintain liver homeostasis, excessive accumulation of secondary bile acids such as DCA and LCA induce liver damage and promote liver cancer. Elucidating the pathogenesis of liver disease through the gut-liver axis might lead to the development of a method for preventing liver disease through control of gut microbiota.