GPR43
Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are the major anions in the large intestinal lumen. They are produced from dietary fiber by bacterial fermentation and are known to have a variety of physiological and pathophysiological effects on the intestine. The short-chain free fatty acid receptor GPR43 is a G-protein-coupled receptor that is activated by physiological concentrations of short-chain fatty acids (SCFAs), primarily acetate and propionate. GPR43 is expressed in a variety of tissues including immune cells, adipocytes, pancreatic β-cells, and enteroendocrine L-cells. Colonic fermentation of dietary fiber produces large amounts of SCFAs, and results indicate that an interplay between GPR43 and dietary fiber via colonic fermentation to produce SCFAs is implicated in promoting a healthy composition of microorganisms in the gut. Fiber-rich diets and SCFAs can counteract colitis, and exacerbated inflammation in colitis models has been reported for GPR43-knockout mice. However, others have found that GPR43-knockout mice exhibited reduced inflammatory responses in colitis models. Thus, both agonists and antagonists of GPR43 are considered to be the potential treatment of intestinal inflammation[1,2].