Toll-like receptor 4 mediates ischemia/reperfusion injury of the heart
Toll-like receptor 4 mediates ischemia/reperfusion injury of the heart
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DOI：
10.1016/j.jtcvs.2003.11.036
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发表时间：
2004-08-01
影响因子：
6
通讯作者：
Verrier, ED
中科院分区：
文献类型：
--
作者：
Chong, AJ;Shimamoto, A;Verrier, ED
背景：缺血心脏血流的恢复可能矛盾地加剧组织损伤（缺血/再灌注损伤）。toll样受体4在包括心肌细胞在内的几种细胞类型上表达，是宿主对感染的炎症反应的介质。由于缺血/再灌注损伤以急性炎症反应为特征，我们在小鼠局部心肌缺血/再灌注损伤模型中研究了toll样受体4的激活。我们使用表达无功能toll样受体4的C3H/HeJ小鼠来评估该受体与缺血心肌再灌注后组织损伤的相关性。方法：野生型小鼠（C3H/HeN）或toll样受体4突变型小鼠（C3H/HeJ）局部心肌缺血60分钟，再灌注2小时。再灌注结束时，测量心肌梗死危险面积和心肌梗死面积，作为心肌缺血再灌注损伤终点。Western blotting检测心肌有丝分裂原活化蛋白激酶的活化，电泳迁移位移法检测核因子κ b和活化蛋白1的核易位。缺血/再灌注损伤心肌也通过核糖核酸酶保护试验评估炎症介质（肿瘤坏死因子- α、白细胞介素-1 β、单核细胞趋化因子-1和白细胞介素-6）的表达。结果：各组心肌缺血再灌注损伤后的危险面积相似。与C3H/HeN小鼠相比，C3H/HeJ小鼠的梗死面积（占危险面积的百分比）减少了40% （P = .001）。在心肌中，与假手术中丝裂原激活蛋白激酶的缺失相比，在缺血和再灌注期间，两株小鼠心肌中均观察到c-Jun n末端激酶、p38和细胞外信号调节激酶的显著激活；然而，C3H/HeJ小鼠的c-Jun n端激酶活性显著降低（P < 0.05），而p38或细胞外信号调节激酶活性未见显著降低（P < 0.05）。心肌缺血/再灌注损伤时，两组心肌均发生核因子- kappab和激活蛋白-1核易位，但密度分析显示，C3H/HeJ小鼠的核因子- kappab和激活蛋白-1核易位明显低于C3H/HeJ小鼠。再灌注缺血心肌检测到白细胞介素-1 β、单核细胞趋化因子-1和白细胞介素-6，假手术心肌未检测到；与对照组C3H/HeN小鼠品系相比，C3H/HeJ小鼠心肌组织中这些介质的表达均显著降低。结论：我们的数据表明toll样受体4可能介导，至少部分介导心肌缺血/再灌注损伤。在临床上，抑制toll样受体4的激活可能是减轻缺血/再灌注引起的组织损伤的潜在治疗靶点。
Background: Restoration of blood flow to the ischemic heart may paradoxically exacerbate tissue injury (ischemia/reperfusion injury). Toll-like receptor 4, expressed on several cell types, including cardiomyocytes, is a mediator of the host inflammatory response to infection. Because ischemia/reperfusion injury is characterized by an acute inflammatory reaction, we investigated toll-like receptor 4 activation in a murine model of regional myocardial ischemia/reperfusion injury. We used C3H/HeJ mice, which express a nonfunctional toll-like receptor 4, to assess the pertinence of this receptor to tissue injury after reperfusion of ischemic myocardium.Methods: Wild-type mice (C3H/HeN) or toll-like receptor 4 mutant mice (C3H/HeJ) were subjected to 60 minutes of regional myocardial ischemia followed by 2 hours of reperfusion. At the end of reperfusion, the area at risk and the myocardial infarct size were measured as the end point of myocardial ischemia/reperfusion injury. Myocardial mitogen-activated protein kinase activation was measured by Western blotting, and nuclear translocation of nuclear factor-kappaB and activator protein-1 was determined by electrophoretic mobility shift assay. Ischemia/reperfusion-injured myocardium was also assessed by ribonuclease protection assay for expression of inflammatory mediators (tumor necrosis factor-alpha, interleukin-1beta, monocyte chemotactic factor-1, and interleukin-6).Results: The area at risk was similar for all groups after myocardial ischemia/reperfusion injury. There was a 40% reduction in infarct size (as a percentage of the area at risk) in C3H/HeJ mice compared with C3H/HeN mice (P = .001). Within the myocardium, significant activation of c-Jun N-terminal kinase, p38, and extracellular signal-regulated kinase was observed in both strains after ischemia and during reperfusion as compared with an absence of mitogen-activated protein kinase activation during sham operations; however, c-Jun N-terminal kinase activity, but not p38 or extracellular signal-regulated kinase activity, was significantly reduced in C3H/HeJ mice (P < .05). In both groups, nuclear factor-kappaB and activator protein-1 nuclear translocation occurred in the myocardium during myocardial ischemia/reperfusion injury, but, by densitometric analysis, nuclear translocation of nuclear factor-kappaB and activator protein-1 was significantly decreased in C3H/HeJ mice compared with C3H/HeJ mice. Interleukin-1beta, monocyte chemotactic factor-1, and interleukin-6 were detectable in reperfused ischemic myocardium but were not detected in sham-operated myocardium; the expression of each of these mediators was significantly decreased in the myocardial tissue of C3H/HeJ mice when compared with expression in the control C3H/HeN mouse strain.Conclusions: Our data suggest that toll-like receptor 4 may mediate, at least in part, myocardial ischemia/reperfusion injury. Inhibition of toll-like receptor 4 activation may be a potential therapeutic target to attenuate ischemia/reperfusion-induced tissue damage in the clinical setting.