Oxidized low-density lipoprotein induces autophagy in macrophages via CD36-mediated oxidative stress / 中国病理生理杂志

ABSTRACT

[ ABSTRACT] AIM:To investigate the effect of oxidized low-density lipoprotein ( ox-LDL) on autophagy in mac-rophages and the underlying molecular mechanisms.METHODS:RAW264.7 macrophages were pretreated with 2 mg/L anti-CD36 monoclonal antibody (anti-CD36 mAb), 5 μmol/L diphenyleneiodonium (DPI), 3 mmol/L 3-methyladenine (3-MA) or 1μmol/L rapamycin for 1 h and then treated with ox-LDL (100 mg/L) for 12 h.The viability of the cells was measured by MTT assay.The activities of lactic dehydrogenase ( LDH) in the medium and nicotinamide adenine dinucleoti-de phosphate ( NADPH) oxidase, superoxide dismutase ( SOD) in the cells as well as the levels of intracellular reactive ox-ygen species ( ROS) and malondialdehyde ( MDA) were determined to characterize the membrane integrity and the oxida-tive stress, respectively.The protein levels of beclin-1 and microtubule-associated protein 1 light chain 3-II ( LC3-II) , 2 important molecular markers of autophagy, were examined by Western blotting.RESULTS:ox-LDL induced autophagy in RAW264.7 macrophages as assessed by upregulation of beclin-1 and LC3-II.Similar to 3-MA, an autophagy inhibitor, an-ti-CD36 mAb significantly inhibited the ox-LDL-induced upregulation of beclin-1 and LC3-II.Anti-CD36 mAb suppressed the ox-LDL-induced oxidative stress as revealed by decreased NADPH oxidase activation, ROS and MDA generation as well as increased SOD activity.Similar results were observed in the cells pretreated with DPI, a NADPH oxidase inhibitor.Mo-reover, DPI significantly inhibited the ox-LDL-induced upregulation of beclin-1 and LC3-II.Inaddition, the decrease in the cell viability and increase in LDH release induced by ox-LDL were promoted by 3-MA and blocked by rapamycin ( an auto-phagy inducer).CONCLUSION: ox-LDL induces autophagy in RAW264.7 macrophages, which may be involved in CD36-mediated ox-LDL uptake and subsequent activation of oxidative stress, and moderate activation of autophagy may pro-tect macrophages from ox-LDL-induced injury.