knockout mice are protected against lithogenic diet-induced gallstones.

The scavenger receptor and multiligand transporter CD36 functions to promote cellular free fatty acid uptake and regulates aspects of both hepatic and intestinal cholesterol metabolism. However, the role of CD36 in regulating canalicular and biliary cholesterol transport and secretion is unknown. Here, we show that germline knockout (KO) mice are protected against lithogenic diet (LD)-induced gallstones compared with congenic (C57BL6/J) controls. KO mice crossed into congenic KO mice (DKO mice) demonstrated protection against LD-induced gallstones, reversing the susceptibility phenotype observed in KO mice. DKO mice demonstrated reduced biliary cholesterol secretion and a shift into more hydrophophilic bile acid species, without changes in either BA pool size or fecal excretion. In addition, we found that the mean and maximum force of gallbladder contraction was increased in germline KO mice, and gallbladder lipid content was reduced compared with wild-type controls. Finally, whereas germline KO mice were protected against LD-induced gallstones, neither liver- nor intestine-specific KO mice were protected. Taken together, our findings show that CD36 plays an important role in modifying gallstone susceptibility in mice, at least in part by altering biliary lipid composition, but also by promoting gallbladder contractility.