The relationship between LDL oxidation and macrophage myeloperoxidase activity

OBJECTIVE: To explore low density lipoprotein (LDL) oxidation by macrophage myeloperoxidase (MPO) at molecular level. METHODS: Using a mouse macrophage model, we examined the relationship between LDL oxidation and macrophage MPO by measuring macrophage MPO activity, LDL oxidation products, MPO gene expression and cellular orientation of LDL oxidation. RESULTS: MPO gene expression increased to its maximum gradually when the concentration of LDL was increased, and then maintained at that level. NaN(3) inhibied the elevation of MPO activity and LDL oxidation, which was LDL concentration-dependent. After the composition of macrophage membrane was roughly analyzed, it was determined that the contents of MPO and LDL in 5% sucrose were 7.667 and 21 times higher than those in 10% sucrose, respectively. CONCLUSION: LDL is attached to the "microdomain" of the macrophage membrane in which LDL is oxidized by MPO.