TLR4/MAPKs信号通路在ox-LDL诱导的血管平滑肌细胞分泌MCP-1中的作用

目的:探讨Toll样受体4/丝裂原活化蛋白激酶(TLR4/MAPKs)信号通路在氧化性低密度脂蛋白(ox-LDL)诱导的血管平滑肌细胞分泌单核细胞趋化因子-1(MCP-1)中的作用。方法:在ox-LDL刺激下采用逆转录聚合酶链技术(RT-PCR)和酶联免疫吸附试验(ELISA)检测血管平滑肌细胞MCP-1的表达,用Western blotting检测细胞外信号调节激酶(ERK1/2)、p38促分裂原活化蛋白激酶(p38MAPK)磷酸化水平的变化。同时,分别应用TLR4中和抗体(TLR4单克隆抗体、TLR4阻断剂)、PD98059(ERK1/2特异性抑制剂)、SB23015(p38MAPK特异性抑制剂)、SP600125(JNK特异性抑制剂),观察其对ox-LDL诱导的MCP-1的表达和ERK1/2、p38MAPK磷酸化水平的影响。结果:ox-LDL刺激血管平滑肌细胞上调MCP-1mRNA和其蛋白的表达(P0.05);用TLR4中和抗体、PD98059、SB23015预孵育后MCP-1mRNA和其蛋白的表达较单独ox-LDL刺激情况下降低(P0.05),而用SP600125预孵育后降低不明显(P0.05);TLR4调节了ERK1/2和p38MAPKs的磷酸化水平。结论:ox-LDL是TLR4的内源性配体;ox-LDL通过或部分通过TLR4/ERK1/2和TLR4/p38MAPK信号通路介导血管平滑肌细胞MCP-1的表达。

Role of Toll-like receptor 4/MAPKs pathway on monocyte chemoattractant protein-1 secretion induced by oxidized low density lipoprotein in vascular smooth muscle cells

AIM: To investigate the role of Toll-like receptor 4/MAPKs pathway on the secretion of monocyte chemoattractant protein-1 (MCP-1) induced by oxidized low density lipoprotein (ox-LDL) in the vascular smooth muscle cells (VSMCs). METHODS: mRNA and protein expressions of MCP-1 in VSMCs stimulated with oxidized low density lipoprotein were determined by RT-PCR and ELISA, respectively. The phosphorylated forms of ERK1/2 and p38MAPK were determined by Western blotting. TLR4 neutralizing antibodies (a specific TLR4 inhibitor), PD98059 (ERK1/2 specific inhibitor), SB23015 (p38MAPK specific inhibitor) and SP600125 (JNK specific inhibitor) were used to investigate the underlying mechanisms. RESULTS: The mRNA and protein expressions of MCP-1 in VSMCs were up-regulated by ox-LDL (P<0.05), while those were inhibited by TLR4 neutralizing antibodies, PD98059 or SB23015 (P<0.05), but not by SP600125 (P>0.05). TLR4 had regulatory effect on the phosphorylation of ERK1/2 and p38MAPK. CONCLUSION: ox-LDL is an endogenous ligand of TLR4. The secretion of MCP-1 induced by ox-LDL in VSMCs is at least in part via TLR4/ERK1/2 and TLR4/p38MAPKs pathways.