Abstract
Nonalcoholic steatohepatitis (NASH) is a rapidly developing pathology around the world, with limited treatment options available. Some farnesoid X receptor (FXR) agonists have been applied in clinical trials for NASH, but side effects such as pruritus and low-density lipoprotein elevation have been reported. Intestinal FXR is recognized as a promising therapeutic target for metabolic diseases. Glycine-β-muricholic acid (Gly-MCA) is an intestine-specific FXR antagonist previously shown to have favorable metabolic effects on obesity and insulin resistance. Herein, we identify a role for Gly-MCA in the pathogenesis of NASH, and explore the underlying molecular mechanism. Gly-MCA improved lipid accumulation, inflammatory response, and collagen deposition in two different NASH models. Mechanistically, Gly-MCA decreased intestine-derived ceramides by suppressing ceramide synthesis-related genes via decreasing intestinal FXR signaling, leading to lower liver endoplasmic reticulum (ER) stress and proinflammatory cytokine production. The role of bile acid metabolism and adiposity was excluded in the suppression of NASH by Gly-MCA, and a correlation was found between intestine-derived ceramides and NASH severity. This study revealed that Gly-MCA, an intestine-specific FXR antagonist, has beneficial effects on NASH by reducing ceramide levels circulating to liver via lowering intestinal FXR signaling, and ceramide production, followed by decreased liver ER stress and NASH progression. Intestinal FXR is a promising drug target and Gly-MCA a novel agent for the prevention and treatment of NASH.