TLR2拮抗剂T2.5通过MyD88信号通路下调MMP-9减轻缺血性脑损伤

摘要

Objective To investigate the mechanism of action of toll-like receptor 2 (TLR2),myeloid differentiation factor 88 (MyD88),and matrix metalloproteinase-9 (MMP-9) in cerebral ischemia-reperfusion injury in rats.Methods One hundred twenty-fiwe adult male SD rats were randomly divided into sham operation group,cerebral ischemia group and T2.5 (TLR2 antagonist) treatment group.A model of middle cerebral artery occlusion was induced by suture method.T2.5 (0.121 2 μg/g) was injected into jugular vein at the beginning of reperfusion in the T2.5 treatment group.Cerebral infarction volume,brain edema,bloodbrain barrier permeability and neurological deficit score were measured at 24 h after reperfusion.Western blotting was used to determine the expression levels of TLR2,MyD88 and MMP-9 at different time points in the ischemic cortex.Results Western blot analysis showed that compared with the sham operation group,the expression levels of TLR2 and MyD88 in the ischemic group increased significantly from 6 h after ischemia-reperfusion and lasted for 24 h (all P ＜ 0.05),while MMP-9 increased significantly at 24 h after ischemia-reperfusion (P ＜ 0.05).At 24 h after ischemia-reperfusion,the blood-brain barrier permeability,brain edema degree,cerebral infarction volume,and neurological deficit score in the ischemic group were significantly higher than those in the sham operation group (all P ＜0.05);at this time,the expression levels of TLR2,MyD88 and MMP-9 in the T2.5 treatment group were significantly lower than those in the ischemic group (all P＜ 0.05),and the blood-brain barrier permeability,brain edema degree,cerebral infarction volume,and neurological deficit score were significantly reduced (all P＜ 0.05).Conclusion TLR2,MyD88 and MMP-9 might be involved in cerebral ischemia-reperfusion injury.TLR2 antagonist T2.5 might inhibit the expression of MMP-9 through TLR2-MyD88 signaling pathway,thus alleviating cerebral ischemia-reperfusion injury.%目的 探讨Toll样受体2(Toll-like receptor 2,TLR2)、髓样分化因子88(myeloid differentiation factor 88,MyD88)和基质金属蛋白酶9(matrix metaUoproteinase-9,MMP-9)在大鼠脑缺血再灌注损伤中的作用机制.方法 125只成年雄性SD大鼠随机分为假手术组、脑缺血组和TLR2拮抗剂T2.5处理组.通过线栓法建立大脑中动脉闭塞2h再灌注模型,T2.5组于再灌注开始时经颈静脉注射T2.5(0.121 2μg/g).再灌注24 h时测定脑梗死体积、脑水肿程度、血脑屏障通透性以及神经功能缺损评分.应用蛋白质印迹法测定缺血侧皮质不同时间点TLR2、MyD88和MMP-9表达.结果 蛋白质印迹分析显示,缺血组从缺血再灌注后6h开始TLR2和MyD88蛋白表达水平较假手术组显著升高,并持续至24 h(P均＜0.05);而MMP-9在缺血再灌注后24 h才显著升高(P＜0.05).缺血再灌注后24 h时,缺血组血脑屏障通透性、脑水肿程度、脑梗死体积和神经功能缺损评分均较假手术组显著增高(P均＜0.05);此时,T2.5组TLR2、MyD88和MMP-9表达均较缺血组显著降低(P均＜0.05),且血脑屏障通透性、脑水肿程度、脑梗死体积和神经功能缺损评分均显著降低(P均＜0.05).结论 TLR2、MyD88和MMP-9可能参与了脑缺血再灌注损伤.TLR2拮抗剂T2.5可能通过TLR2-MyD88信号通路抑制MMP-9表达,从而减轻缺血再灌注脑损伤.