HDL3 exerts more powerful anti-oxidative, protective effects against copper-catalyzed LDL oxidation than HDL2

Objective: To evaluate which HDL subfraction, HDL2 or HDL3, exerts the greater preventive effect on the Cu2+-induced LDL oxidation. Methods: LDL was incubated for 6 h with 2.5 mu M Cu2+ in phosphate-buffered saline alone, or in the presence of HDL2 or HDL3 at various protein concentrations. Each sample was subjected to agarose gel electrophoresis, and the amount of lipid hydroperoxide in each sample of LDL was measured. Results: There was no significant difference in the levels of LPO between the LDL and LDL + HDL2 cases, whereas a significant reduction was apparent with LDL + HDL3. Both HDL2 and HDL3 significantly inhibited oxidative modification of LDL, as assessed by electrophoretic mobility, in a concentration dependent manner, but this effect was much more pronounced with HDL3. Conclusion: HDL3 may play an important role in the prevention of atherosclerosis in vivo, more effectively inhibiting oxidation of LDL than HDL2.