Alpha-2-antiplasmin and Ischemic Stroke

 描述(由申请人提供)： 作为导致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，恢复血液流动，缓解大脑缺血。不幸的是，在长时间的缺血后，TPA可能会导致严重或致命的并发症；这限制了TPA的使用，仅限于少数中风患者。尽管TPA为治疗性纤溶提供了一个模型，但最近的数据表明，一种新的范式将调节分子如α-2-抗纤溶酶(A2AP)分配给决定缺血性卒中后预后的核心角色。临床观察表明，高a2AP水平可能会增加缺血性中风和TPA失败的风险。在挑战目前中风纤溶治疗模式的实验中，我们已经表明，a2AP以剂量依赖的方式显著增加了脑损伤。相反，a2AP缺乏或a2AP的单抗失活，可显著减少脑损伤、细胞凋亡、出血和肿胀。即使在长时间的脑缺血后，a2AP的失活也能减少微血管血栓形成和基质金属蛋白酶-9的表达(急性炎症的标志)。因此，A2AP失活可以防止缺血性中风后的死亡和残疾。因此，与TPA相比，a2AP失活似乎为改善卒中治疗提供了一种安全有效的方法，通过NINDS的合作，我们正在寻求a2AP失活疗法的发展。这项建议试图确定a2AP增强血栓栓塞性中风后缺血性脑损伤的病理生理机制。组织假说是，a2AP通过纤溶酶原依赖的机制促进微血管血栓形成的发展，并损害下游的微血管灌流。通过这些机制，a2AP促进炎症反应的发展，如基质金属蛋白酶-9的表达和中性粒细胞的募集，这些都具有急性有害的影响。目的1验证以下假设：a2AP在缺血性卒中中的有害作用是由于纤溶酶(原)依赖的内源性纤溶作用减弱，通过影响血栓形成和下游凝血酶依赖的微血管血栓的形成而损害微血管的血流。我们还建议检验假说(目标2)，即a2AP调节内源性纤溶系统，通过炎症相关途径影响血栓栓塞性卒中缺血性损伤、出血、肿胀和存活的发展，而炎症相关途径需要基质金属蛋白酶-9活性和中性粒细胞沉积。最后，我们将使用与特定的a2AP突变体的分子互补来检验这一假设，即a2AP分子中的特定结构元素选择性地增强不良后果(如神经元损伤、出血等)。在缺血性中风中。

 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.