HDL2 can inhibit further oxidative modification of partially oxidized LDL.

Aim: To investigate whether HDL(2) can inhibit further oxidative modification of partially oxidized LDL (ox-LDL) by interrupting the chain oxidation reaction after lipid hydroperoxides (LOOH) formation.

Methods: Following incubation of LDL 400 microg protein/mL phosphate-buffered saline with Cu(2+) for 1.75 h (defined as 0 min), incubation was continued after adding HDL(2) 200 microg protein/mL or HDL(2) 800 microg protein/mL to give both ox-LDL+HDL(2) 200 microg protein/mL or ox-LDL+HDL(2) 800 microg protein/mL. As a control, ox-LDL 200 microg protein/mL and native LDL were prepared. Each sample was subjected to agarose gel electrophoresis and the LOOH in each sample was measured.

Results: When the electrophoretic mobility of native LDL was designated 1, the relative electrophoretic mobility (REM) of ox-LDL increased significantly over time. The REMs of ox-LDL+HDL(2) 800 microg protein/mL from 10 min to 9 h were significantly lower than the REM of ox-LDL at the respective times (p<0.01). LOOH of ox-LDL+HDL(2) 800 microg protein/mL at 1, 3, 6 and 9 h was significantly higher than LOOH in ox-LDL at the respective times (p<0.01). The results of ox-LDL+HDL(2) 200 microg protein/mL were almost the same but to a lesser extent than the results of ox-LDL+HDL(2) 800 microg protein/mL.

Conclusion: The present findings suggest that HDL(2) can inhibit further oxidative modification of partially oxidized LDL by interrupting the chain oxidation reaction after LOOH formation in a concentration-dependent manner.