Biliary and nonbiliary contributions to reverse cholesterol transport

Purpose of Review: The process of reverse cholesterol transport (RCT) is critical for disposal of excess cholesterol from the body. Although it is generally accepted that RCT requires biliary secretion, recent studies show that RCT persists in genetic or surgical models of biliary insufficiency. Discovery of this nonbiliary pathway has opened new possibilities of targeting the intestine as an inducible cholesterol excretory organ. In this review we highlight the relative contribution and therapeutic potential for both biliary and nonbiliary components of RCT. Recent Findings: Recently, the proximal small intestine has gained attention for its underappreciated ability to secrete cholesterol in a process called transintestinal cholesterol efflux (TICE). Although this intestinal pathway for RCT is quantitatively less important than the biliary route under normal physiological conditions, TICE is highly inducible, providing a novel therapeutic opportunity for treatment of atherosclerotic cardiovascular disease (ASCVD). In fact, recent studies show that intestine-specific activation of RCT protects against ASCVD in mice. Summary: It is well known that the small intestine plays a gatekeeper role in the maintenance of cholesterol balance. Through integrated regulation of cholesterol absorption and TICE, the small intestine is a key target for new therapies against ASCVD.