CholesterintransportWirkung

Cholesterintransport is the process by which cholesterol is moved through the circulatory system and between tissues. In humans, cholesterol is transported in the aqueous environment of blood by lipoproteins. Major lipoproteins include chylomicrons, very low-density lipoproteins (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL). Chylomicrons deliver dietary cholesterol from the intestine to tissues; VLDL and LDL convey endogenously synthesized cholesterol; HDL participates in reverse cholesterol transport, carrying cholesterol away from peripheral cells to the liver for disposal.

Cholesterol is not water-soluble; its transport relies on lipid-protein particles with a core of triglycerides and cholesteryl esters surrounded by a monolayer of phospholipids and apolipoproteins. Apolipoproteins serve as ligands for receptors and cofactors for enzymes; for example ApoB-100 is essential for LDL particle structure and hepatic uptake, while ApoA-I is central to HDL formation and function. Enzymes such as lipoprotein lipase and lecithin–cholesterol acyltransferase remodel lipoproteins during transit.

Cellular cholesterol transport involves transporters and cholesterol efflux pathways. In cells, cholesterol is moved by NPC1L1 in intestinal enterocytes and transported across membranes via ABCA1 and ABCG1 to apolipoproteins, enabling HDL formation. LDL receptors mediate endocytosis of LDL, delivering cholesterol to cells for membrane synthesis or hormone production.

Disorders of cholesterol transport, such as familial hypercholesterolemia, raise cardiovascular risk. Therapies include statins, ezetimibe, PCSK9 inhibitors, and lifestyle measures that influence lipoprotein levels and transport efficiency.