Effects of Quercetin on Inflammatory Reactions Induced by Oxidized Low Density Lipoprotein in Vascular Smooth Muscle Cells

Objective:To investigate the effects of quercetin(Que) on oxidized low density lipoprotein(ox-LDL)-induced cytokines secretion in vascular smooth muscle cells(VSMCs). Methods:The effect of quercetin with different concentrations on the activity of VSMCs was determined by MTT method. VSMCs were divided into 5 groups: A group(control group), B group(ox-LDL group), C group(ox-LDL+Que 50 μmol/L), D group(ox-LDL+Que 100 μmol/L) and E group(ox-LDL+Que 200 μmol/L), and the concentration of ox-LDL in all groups was 100 μg/m L.The levels of monocyte chemoattractant protein(MCP-1) and Tumor necrosis factor(TNF)-α in cell supernatant in each group was determined by ELISA. m RNA expression of Toll-like receptor 4(TLR4) and myeloid differentiation factor 88(Myd88) was determined by fluorescent quantitative PCR(real-time RT-PCR). The protein expression of TLR-4, Myd88 and nuclear transcription factor(NF)-κB(p65) was determined by Western-blot method. Results:Quercetin did not show significant cytotoxicity in the range of 0~250 mol/L. Quercetin can significantly inhibit MCP-1 and TNF-α secretion in VSMCs, reduce TLR4, My D88 m RNA and protein expression and inhibit ox-LDLinduced NF-κB(p65) nuclear transposition compared with ox-LDL group, showing dose-dependent manner(P<0.01). Pretreatment of TLR4 and TNF-α(p65) inhibitor has similar effect to quercetin. Conclusion:Quercetin can reduce oxLDL-induced cytokines secretion in VSMCs, which may depend on regulating TLR4-mediated signaling pathway.