Mechanisms of complement induced endothelial dysfunction

虽然缺血/再灌注损伤的确切机制尚不清楚，但我们的实验室和其他实验室已经 研究表明，抑制补体激活(例如，sCR1或C1酯酶抑制剂)、耗尽补体 成分(如眼镜蛇毒素)和补体成分(如C3和C4)缺乏的小鼠显示出 补体在缺血再灌注损伤中的重要作用。在上一个资金周期中，我们表现出了抑制 甘露糖结合凝集素(MBL)对缺血胃肠系统的保护作用 事件。相比之下，肺部系统受到原发的胃肠道缺血的第二次打击 大片地区，没有受到保护。在C1qA或MBL缺陷小鼠的肺中观察到补体激活，但 在C2/B因子缺陷(KO)小鼠中不存在。添加C2恢复了补体的激活和组织 C2/FB KO小鼠胃肠道缺血/再灌注后的炎症/损伤。这些数据 建议C2依赖，但C1q或MBL独立的过程负责补充 GI/R后的激活、炎症和损伤初步数据表明，另一种凝集素，无花果碱-A是 GI/R后负责肺部补体激活的启动分子最近发表的文章还 表明涉及MBL的C2/C4旁路机制可能通过 另一条路径。初步研究证实了体外这种旁路机制的生物学证据 以及涉及MBL复合体和凝血系统的几个潜在的分子机制。研究 其他人展示了与凝血系统和补体的几种不同的相互作用。使用FeCl3 动脉血栓形成模型，我们观察到在MBL缺失的小鼠中没有血栓形成，但仍存在 C2/Fb基因缺失小鼠。我们表明，创伤患者表现出补体激活和 早期观察到的凝血障碍与MBL水平显著降低。这些互动中至少有一个 LINKS包括由MBL复合体直接激活替代途径，而不需要C2 或者C4。我们的初步数据显示凝集素复合体与凝血蛋白和 可以解释为什么抑制补体在CABG和CAD的临床研究中被证明不成功， 需要更好地了解补体与凝血系统的复杂相互作用。在……里面 这次竞争性更新，我们将继续研究补体所涉及的分子机制 体内外内皮细胞氧化应激激活及其与凝血的相互作用 卡斯卡德。本应用的总体目标是描述控制凝集素的分子机制 内皮氧化应激后诱导的凝血激活。这次更新中的研究将调查 补体活化的分子机制及补体与凝血蛋白的相互作用。 我们还将描述最近发现的一种新型补体抑制剂的潜在用途， 自我们上次提交以来克隆和表达，是凝集素复合体的一部分。

While the exact mechanisms of ischemia/reperfusion injury remain unclear, our laboratory and others have shown that inhibition of complement activation (e.g., sCR1 or C1 esterase inhibitor), depletion of complement components (e.g., cobra venom factor) and complement component (e.g., C3 and C4) deficient mice reveal an important role of complement in ischemia/reperfusion injury. In the last funding cycle, we showed that inhibition of mannose binding lectin (MBL) protected the ischemic gastrointestinal system from the primary ischemic event. In contrast, the pulmonary system, which takes a second hit from the primary ischemic gastrointestinal tract, was not protected. Complement activation in the lung was observed in C1qa- or MBL-deficient mice, but not in C2/factor B deficient (KO) mice. Addition of C2 restored the complement activation and tissue inflammation/injury in the C2/fB KO mice following gastrointestinal ischemia/reperfusion (GI/R). These data suggest that a C2 dependent, but C1q or MBL independent, process is responsible for the complement activation, inflammation and injury following GI/R. Preliminary data suggest that another lectin, ficolin-A is the initiating molecule responsible for complement activation in the lungs following GI/R. Recent publications also showed a C2/C4 bypass mechanism involving MBL may be responsible for complement activation via the alternative pathway. Preliminary studies demonstrate biological evidence of this bypass mechanism in vitro and several potential molecular mechanisms involving the MBL complex and the coagulation system. Studies by others show several different interactions with the coagulation system and complement. Using the FeCl3 model of arterial thrombogenesis, we observed that thrombogenesis was absent in MBL null mice, yet present in C2/fB null mice. We show that trauma patients demonstrate a link between complement activation and coagulopathy with a significant decrease in MBL levels observed early on. At least one of these interacting links involves the direct activation of the alternative pathway by the MBL complex, bypassing the need for C2 or C4. Our preliminary data demonstrate multiple interactions of lectin complexes with coagulation proteins and may explain why inhibition of complement has proven unsuccessful in clinical studies for CABG and CAD, warranting a better understanding of the complex interactions of complement with the coagulation system. In this competitive renewal, we will continue to investigate the molecular mechanisms involved in complement activation during oxidative stress of endothelial cells in vitro and in vivo and its interactions with the coagulation cascade. The general aim of this application is to characterize the molecular mechanisms governing lectin induced activation of coagulation following endothelial oxidative stress. Studies in this renewal will investigate the molecular mechanism of complement activation and interactions of complement with coagulation proteins. We will also be characterizing the potential use of a novel complement inhibitor that was recently discovered, cloned and expressed since our last submission, and is part of the lectin complex.