Impaired fluidity and oxidizability of HDL hydrophobic core and amphipathic surface in dyslipidemic men

Objective: To examine and compare the composition, fluidity and oxidizability of HDL hydrophobic core and amphipathic surface of two groups of adult males (25kg/m(2)<BMI<30kg/m(2)), the former mixed dyslipidemic patients (MD) and the latter age- and BMI-matched healthy controls. Methods and results: Pyrenyl-cholesteryl ester and pyrenyl-phosphatidylcholine, respectively incorporated in HDL core or surface were used for measuring both 2,2'-azobis-2-methyl-propanimidamide-dihydrochloride-induced peroxidation kinetics and fluidities of these regions. In comparison with the controls, MD HDL showed: a) higher free cholesterol to phospholipid ratio in surface and triacylglycerols to cholesteryl ester ratio in the core, b) higher malondialdehyde levels and lower alpha-tocopherol and beta-carotene to neutral lipid ratios, c) a more rigid surface and more fluid core, d) dramatically decreased lag-time and increased propagation rate of peroxidation kinetic in the core, but only an increased propagation rate on the surface. Conclusion: These results suggest that better knowledge of the physical-chemical properties and oxidizability of HDL core and surface could contribute to better understanding of the mechanisms connecting HDL alteration to increased risk of CDV in MD.