Curcumin inhibits LPS-induced inflammation in rat vascular smooth muscle cells in vitro via ROS-relative TLR4-MAPK/NF-KB pathways

Aim： To investigate whether curcumin （Cur） suppressed lipopolysaccharide （LPS）-induced inflammation in vascular smooth muscle cells （VSMCs） of rats, and to determine its molecular mechanisms. Methods Primary rat VSMCs were treated with LPS （1 pg/L） and Cur （5, 10, or 30 pmol/L） for 24 h. The levels of MCP-1, TNF-a, and iNOS were measured using ELISA and real-time RT-PCR. NO level was analyzed with the Griess reaction. Western-blotting was used to detect the activation of TLR4, MAPKs, IKB（x, NF-KB p65, and the p47ph~x subunit of NADPH oxidase in the cells. Results： Treatment of VSMCs with LPS dramatically increased expression of inflammatory cytokines MCP-1 and TNF-a, expression of TLR4 and iNOS, and NO production. LPS also significantly increased phosphorylation of IKBa, nuclear translocation of NF-KB （p65） and phosphorylation of MAPKs in VSMCs. Furthermore, LPS significantly increased production of intracellular ROS, and decreased expres- sion of p47phox subunit of NADPH oxidase. Pretreatment with Cur concentration-dependently attenuated all the aberrant changes in LPS-treated VSMCs. The LPS-induced overexpression of MCP-1 and TNF-（x, and NO production were attenuated by pretreatment with the ERK inhibitor PD98059, the p38 MAPK inhibitor SB203580, the NF-KB inhibitor PDTC or anti-TLR4 antibody, but not with the JNK inhibitor SP600125.Conclusion： Cur suppresses LPS-induced overexpression of inflammatory mediators in VSMCs in vitro via inhibiting the TLR4-MAPK/ NF-KB pathways, partly due to block of NADPH-mediated intracellular ROS production.