High Density Lipoprotein Trafficking of Cholesterol

High density lipoprotein (HDL) is the smallest of the lipoproteins that transport lipids in the plasma. HDL particles apart from their participation in peripheral cholesterol transport also have distinct immunologic and antiatherogenic properties which are now referred to as the functionality of the HDL particle. There seems to be little relationship between HDL particle functionality and the cholesterol content of HDLs, namely HDLcholesterol (HDL-C) or HDL sizes. There are many genetic, lifestyle, hormonal, metabolic and inflammatory influences on HDL’s makeup and function and many of these may be manipulated by pharmacologic and lifestyle interventions. Structurally HDLs are similar to all lipoproteins with a one molecule thick surface of phospholipids (PL) and free or unesterified cholesterol (UC) and a core of mostly cholesteryl ester (CE) but also some triglycerides (TG). On the surface are numerous proteins including the main structural protein which is 1 to 4 copies of apolipoprotein A-I.