Effect of quercetin on ox-LDL-induced lipid accumulation and peroxidation in mouse macrophages

AIM：To investigate the effect of quercetin (QUE) preconditioning on oxidized low-density lipoprotein (ox-LDL)-induced lipid accumulation and peroxidation in mouse RAW264.7 macrophages and the underlying molecular mechanisms. METHODS：RAW264.7 cells were pretreated with different concentrations (20, 40 and 80 μmol/L) of QUE for 30 min and then treated with ox-LDL (100 mg/L) for 24 h. Intracellular lipid droplets were assayed by oil red O staining. Extracellular lactate dehydrogenase (LDH) and malondialdehyde (MDA) and intracellular reactive oxygen species (ROS) were determined to characterize the membrane integrity and the lipid peroxidation, respectively. The mRNA and protein levels of CD36, an important scavenger receptor which mediates ox-LDL uptake, were examined by real-time PCR and Western blotting, respectively. RESULTS：Pretreatment with QUE (20, 40 and 80 mmol/L) significantly attenuated ox-LDL-induced lipid accumulation in RAW264.7 cells and foam cell formation in a dose-dependent manner. Ox-LDL induced LDH release in RAW264.7 cells. This cytotoxic effect was significantly inhibited by QUE pretreatment. Compared with ox-LDL group, the intracellular ROS content and MDA level in culture medium decreased markedly in QUE group. In addition, pretreatment with QUE attenuated ox-LDL-induced up-regulation of CD36 at mRNA and protein levels. CONCLUSION: QUE inhibits ox-LDL-induced lipid accumulation and peroxidation in mouse macrophages and the mechanism may partially involve its ability to down-regulate CD36 expression.