Molecular Studies of Hemolytic Thrombosis

多器官机械循环支持装置（MCSD）的主要并发症 支持的是血栓形成和出血的二分病理学。血管内 与MCSD相关的溶血产生游离血红蛋白（fHb）。吸附 纤维蛋白原和血管性血友病因子（VWF）在非生物表面捕获 可能聚集的血小板。我们报道高水平的fHb增加VWF- 纤维蛋白（原）包被表面介导的血小板粘附和血栓形成。 高剪切应力重要的是，fHb增加福尔马林的流动依赖性粘附 将血小板固定到VWF包被的表面，这表明fHb直接增强了VWF- 糖蛋白（GP）Ib κ相互作用。VWF缺乏或抗GPIb抗体阻断了 通过fHb增强血小板粘附，验证VWF的作用。最后，我们 在暴露于fHb和高剪切全血中鉴定超大VWF（ULVWF） 提示血小板源性ULVWF可能参与血栓形成的病理过程 在高水平fHb的情况下。总之，这些发现提供了第一个证据 高水平的fHb对VWF介导的血栓形成至关重要， 纤维蛋白（原）和来自剪切活化血小板ULVWF多聚体可以增强 在存在fHb的情况下，血栓形成比血浆VWF更强烈。我们的总体 假设fHb靶向VWF，包括血小板衍生的VWF，以促进 通过GPIb介导血小板粘附，并通过促进 VWF到纤维蛋白原。我们建议进行分子、生物化学和结构研究， 研究fHb失调VWF之间相互作用的机制， 纤维蛋白（原）和血小板。目的1探讨血小板VWF与血小板活化因子（VWF）在血小板活化中的作用。 血浆VWF与血栓形成的关系。我们将检验fHb与血小板相互作用的假设， VWF增强血小板与纤维蛋白（原）的粘附， 比血浆VWF强。目的2将检验fHb结合的VWF具有与FHb结合的VWF结合的功能的假设。 有利于血小板粘附的构象。目标3将确定 fHb失调VWF-纤维蛋白（原）相互作用。我们将检验fHb 促进VWF-纤维蛋白（原）结合并调节VWF介导的纤维蛋白 阵这些研究将描述与患者血栓形成相关的新机制 并确定新的，潜在的治疗干预fHb诱导的MCSD的目标。 血栓形成

A major complication of mechanical circulatory support devices (MCSD) for multi-organ support is the dichotomous pathology of thrombosis and bleeding. Intravascular hemolysis associated with MCSD produces free hemoglobin (fHb). Adsorption of fibrinogen and von Willebrand factor (VWF) onto non-biological surfaces captures platelets that may aggregate. We reported that high levels of fHb increased VWF- mediated platelet adhesion and thrombus formation on fibrin(ogen)-coated surfaces at high shear stress. Importantly, fHb increased the flow-dependent adhesion of formalin fixed platelets to a VWF coated surface, suggesting that fHb directly enhances the VWF- glycoprotein (GP)Ib interaction. VWF deficiency or antibodies against GPIb block the enhancement of platelet adhesion by fHb, validating the role of VWF. Lastly, our identification of ultra large VWF (ULVWF) in whole blood exposed to fHb and high shear rates suggests that platelet derived ULVWF may contribute to the pathology of thrombosis in the presence of high levels of fHb. Together, these findings provide the first evidence that high levels of fHb are critical for VWF-mediated thrombosis on surfaces coated with fibrin(ogen), and that ULVWF multimers from shear-activated platelets may enhance thrombosis more robustly than plasma VWF in the presence of fHb. Our overarching hypothesis is that fHb targets VWF, including the platelet-derived VWF, to promote platelet adhesion via GPIb, and potentiate fibrin formation by facilitating the binding of VWF to fibrinogen. We propose molecular, biochemical, and structural studies to investigate the mechanisms by which fHb dysregulates the interactions between VWF, fibrin(ogen), and platelets. Aim 1 will investigate the contributions of platelet VWF vs. plasma VWF to thrombosis. We will test the hypotheses that fHb interaction with platelet VWF enhances platelet adhesion to fibrin(ogen) and potentiates fibrin formation more robustly than plasma VWF. Aim 2 will test the hypothesis that fHb-bound VWF has a conformation that favors platelet adhesion. Aim 3 will determine the mechanism by which fHb dysregulate VWF-fibrin(ogen) interaction. We will test the hypotheses that fHb promotes VWF-fibrin(ogen) association and modulates the VWF-mediated fibrin formation. These studies will describe new mechanisms related to thrombosis in patients on MCSD and identify new, potential targets for therapeutic interventions in fHb-induced thrombosis.