Alpha-2-antiplasmin and Ischemic Stroke

 描述（由申请人提供）： 作为死亡和残疾的第二大原因，缺血性中风每年导致数百万人死亡和残疾。组织纤溶酶原激活剂（TPA）是唯一被批准的治疗方法，它可以溶解罪魁祸首纤维蛋白血栓，恢复血流，缓解大脑缺血。不幸的是，在长时间缺血后，TPA可能导致严重或致命的并发症;这限制了TPA用于少数中风患者。 虽然TPA提供了一个治疗性纤维蛋白溶解的模型，最近的数据表明，一个新的范例，分配一个中心作用的调节分子，如α-2-抗纤溶酶（α 2 AP）在确定缺血性中风后的结果。临床观察表明，高a2 AP水平可能增加缺血性中风和TPA失败的风险。在挑战目前用于中风的纤维蛋白溶解治疗的治疗范例的实验中，我们已经表明α 2 AP以剂量依赖性方式显著增加脑损伤。相反，a2 AP缺乏或a2 AP的单克隆抗体失活，大大减少脑损伤、细胞凋亡、出血和肿胀。即使在长时间脑缺血后，a2 AP失活也减少微血管血栓形成和MMP-9表达（急性炎症的标志物）。因此，a2 AP失活可预防缺血性卒中后的死亡和残疾。因此，当与TPA相比时，α 2 AP失活似乎提供了一种安全有效的方法来改善中风治疗，并且通过NINDS合作，我们正在寻求α 2 AP失活治疗的发展。本研究旨在确定a2 AP增强血栓栓塞性卒中后缺血性脑损伤的病理生理机制。组织假说是a2 AP通过纤溶酶原依赖性机制起作用以增强微血管血栓形成的发展并损害下游微血管灌注。通过这些机制，a2 AP促进具有急性有害作用的炎性反应如MMP-9表达和中性粒细胞募集的发展。目的1将检验以下假设：a2 AP在缺血性中风中的有害作用是由于减少的纤溶酶（原）依赖性内源性纤维蛋白溶解，其通过其对罪犯血栓的作用和下游凝血酶依赖性微血管血栓形成的发展损害微血管血流。我们还建议检验这样的假设（目的2）：a2 AP调节内源性纤维蛋白溶解系统，通过需要MMP-9活性和中性粒细胞沉积的炎症相关途径影响血栓栓塞性中风中缺血性损伤、出血、肿胀和生存的发展。最后，我们将使用与特定a2 AP突变体的分子互补来检验以下假设：a2 AP分子中的特定结构元件选择性地增强不良结果（如神经元损伤、出血等）。缺血性中风

 DESCRIPTION (provided by applicant): As the second leading cause of death and disability, ischemic stroke kills and disables millions of people each year. Tissue plasminogen activator (TPA), the only approved treatment, dissolves the culprit fibrin thrombus to restore blood flow and relieve the brain from ischemia. Unfortunately, after prolonged ischemia, TPA may cause serious or fatal complications; this restricts TPA use to a minority of stroke patients. Although TPA has provided a model for therapeutic fibrinolysis, recent data suggest a new paradigm that assigns a central role to regulatory molecules such as alpha-2-antiplasmin (a2AP) in determining outcomes after ischemic stroke. Clinical observations suggest that high a2AP levels may increase the risk of ischemic stroke and of TPA failure. In experiments that challenge the current therapeutic paradigm for fibrinolytic treatment of stroke, we have shown that a2AP markedly increases brain injury, in a dose-dependent fashion. Conversely, a2AP deficiency or monoclonal antibody inactivation of a2AP, profoundly reduces brain injury, apoptosis, hemorrhage, and swelling. Even after prolonged brain ischemia, a2AP inactivation reduces microvascular thrombosis and MMP-9 expression (a marker of acute inflammation). As a result, a2AP inactivation prevents death and disability after ischemic stroke. Thus, when compared to TPA, a2AP-inactivation appears to provide a safe and effective approach for improving stroke treatment and, through a NINDS collaboration, we are pursuing the development of a2AP inactivation therapy. This proposal seeks to determine the pathophysiologic mechanisms through which a2AP enhances ischemic brain injury after thromboembolic stroke. The organizing hypothesis is that a2AP acts through plasminogen-dependent mechanisms to enhance the development of microvascular thrombosis and impair downstream, microvascular perfusion. Through these mechanisms, a2AP promotes the development of inflammatory responses such as MMP-9 expression and neutrophil recruitment, which have acute deleterious effects. Aim 1 will test the hypothesis that a2AP's deleterious effects in ischemic stroke are due to diminished plasmin(ogen)-dependent, endogenous fibrinolysis that impairs microvascular blood flow through its effect on the culprit thrombus and the development of downstream, thrombin-dependent, microvascular thrombosis. We also propose to examine the hypothesis (Aim 2) that a2AP regulates the endogenous fibrinolytic system to affect the development of ischemic injury, hemorrhage, swelling and survival in thromboembolic stroke through inflammation-linked pathways that require MMP-9 activity and neutrophil deposition. Finally, we will use molecular complementation with specific a2AP mutants to examine the hypothesis that specific structural elements in the a2AP molecule selectively enhance adverse outcomes (such as neuronal injury, hemorrhage, etc.) in ischemic stroke.