Heterogeneity of high density lipoprotein particles

Human high density lipoprotein (HDL) contains at least two types of lipoprotein-containing A-I particles: one contains both apolipoproteins (apo) A-I and A-II (Lp A-I:A-II) as main protein components, whereas in the other, apo A-II is absent (Lp A-I). The two subpopulations have different metabolisms and physiological roles. Studies indicate that apo A-II is an antagonist of cholesterol efflux. Lp A-I but not Lp A-I:A-II is increased in women compared with men. The lower apo A-I levels in patients with coronary artery disease reflect a decrease in Lp A-I. Lp A-I also is decreased in children with a family history of coronary artery disease, and increased in elderly subjects. Despite cholesterol intake remaining constant, a high polyunsaturated:saturated fat diet leads to a decrease in Lp A-I but not Lp A-I:A-II. Chronic alcohol consumption induces an increase in Lp A-I:A-II and a decrease in Lp A-I, although short bouts of drinking produce increases in both Lp A-I and Lp A-I:A-II. Hypolipidemic drugs have specific effects on discrete apo A-I particles.