High-density lipoprotein particles in octogenarians

Abstract

High-density lipoprotein (HDL) particles exhibit considerable heterogeneity, specifically in apolipoprotein (apo) composition. Thus, apo A-I, the major protein of HDL, is present in two types of particles: one species contains both apo A-I and apo A-II (Lp A-I A-II ) while in the other (Lp A-I), apo A-II is absent. We used the hypothesis that octogenarians, who survived periods in life when the incidence of coronary heart disease (CHD) is very high, have several protective factors. We compared HDL-cholesterol (HDL-C), HDL 2-cholesterol (HDL 2-C), HDL 3-cholesterol (HDL 3-C), apo A-I, and apo A-II in octogenarians and younger control subjects smoking less than 10 cigarettes/d and not taking drugs known to affect lipid metabolism. Using a new procedure, we also compared the levels of Lp A-I and Lp A-I A-II . The cholesterol content of total HDL was similar in octogenarian and control (38 ± 8 years) men while HDL 2-C was higher and HDL 3-C, apo A-I, and A-II were lower in octogenarian than in control men. In women, the level of HDL-C and apo A-I was similar in premenopausal and octogenarian subjects but higher in postmenopausal women than in octogenarians, while HDL 2-C and apo A-II were similar in the three groups. In contrast, HDL 3-C was higher in the two groups of control women (premenopausal and postmenopausal) than in octogenarians. However, Lp A-I was significantly elevated in octogenarian men and women (men: 61 ± 14 mg/dL; women: 70 ± 14 mg/dL) by comparison with younger control subjects (men: 48 ± 12 mg/dL; premenopausal women: 53 ± 11 mg/dL; postmenopausal women: 63 ± 19 mg/dL). On the other hand, Lp A-I A-II was clearly lower in octogenarians. The distribution of Lp A-I and Lp A-I A-II values also appeared to be modified by age, a shift of the distribution being observed toward higher values of Lp A-I and lower values of Lp A-I A-II in octogenarians as compared with younger subjects. This observation could signify that a part of the population with a low level of Lp A-I could have a high frequency of CHD during the sixth or seventh decades. Thus, these results are consistent with the protective function of Lp A-I, which has already been perceived through fundamental and angiographic studies.