High density lipoproteins-based therapies for cardiovascular disease

improve the treatment of atherosclerosis. This includes an increasing interest in using HDL as a therapeutic target. HDL COMPOSITION, STRUCTURE, AND FUNCTION HDL are heterogeneous complexes of proteins and lipids differing in shape (nascent discoidal or mature spherical), diameter (8–13 nm), density (1.21–1.063 g/ml), protein and lipid composition, and function.[8] Nascent discoidal HDL are comprised of a cholesterol-containing phospholipid bilayer surrounded by apolipoprotein α-helices.[9] Mature spherical HDL are composed of a monolayer of phospholipids and helical proteins on the surface and cholesterol ester as well as a small amount of triglycerides in the hydrophobic core.[10] Apolipoprotein A-I (apoA-I) is the major protein on HDL that accounts for ~70 % of total HDL proteins. The second major protein, apoA-II, represents ~20%, and other HDL proteins, including apoE, apoA-IV, apoA-V, apoJ, apoC-I, apoC-II, and apoC-III, account for <10 % of the HDL protein content.[11] Based on their density, mature HDL can be further divided into HDL2 (1.063–1.125 g/ml) and HDL3 (1.125–1.21 g/ml). These subclasses vary in protein and lipid composition and have different functions. For example, smaller HDL3 are relatively enriched in apoA-II.[12] Importantly, HDL2 and HDL3 have distinc