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 (25 kg/m(2)<BMI<30 kg/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. (C) 2013 Elsevier Inc. All rights reserved.