The molecular and metabolic basis of biliary cholesterol secretion and gallstone disease

This article presents an up to date of selected aspects of the molecular mechanisms of cholesterol metabolism most likely involved in cholesterol gallstones disease, a highly prevalent disease in the Western world. The etiology of cholesterol cholelithiasis is considered to be multifactorial, with interaction of genetic and environmental factors. The production of supersaturated bile by the liver of cholesterol is a key early metabolic event underlying cholesterol lithogenesis. Regulation of hepatic cholesterol trafficking within the hepatocyte appears essential for the production of cholesterol supersaturated bile. Impaired sorting of metabolically active hepatic free cholesterol to the bile acid biosynthetic or lipoprotein production pathways leads to an increased availability of cholesterol for preferential channeling of cholesterol to the canalicular membrane and further secretion into bile. Many of these intrahepatic cholesterol trafficking steps are under genetic control and might be influenced by a variety of environmental factors. This review summarizes recent discoveries related to transhepatic cholesterol flux and biliary lipid secretion, which have provided new insights to the regulation of hepatic cholesterol metabolism as related to gallstone disease.