Treatment of Acute Embolic Stroke with Statins and rt-PA

描述(申请人提供)：大约80%-90%的人类脑缺血事件是由血栓栓塞症引起的。迫切需要为中风的治疗开发急性治疗干预措施。我们提供的初步数据表明，羟甲基戊二酰辅酶A还原酶抑制剂阿托伐他汀通过激活PI3-K/Akt信号通路延长了栓塞性卒中大鼠的溶栓治疗窗口。然而，阿托伐他汀介导的治疗作用与eNOS和血脂水平无关。本应用的目的是确定他汀类药物联合溶栓治疗急性缺血性卒中的疗效，并探讨阿托伐他汀作为重组人组织型纤溶酶原激活剂(RHT-PA)佐剂的治疗作用机制。我们的假设是：1)阿托伐他汀联合RHT-PA治疗中风延长了急性中风的治疗窗口；2)阿托伐他汀激活了脑内皮细胞中的PI3-K/Akt信号转导通路，通过负调控促进血栓形成、血管通透性和炎症的内皮细胞基因，从而减少了脑微血管血栓形成和血脑屏障(BBB)的渗漏；3)阿托伐他汀激活神经元中的PI3-K/Akt细胞生存通路，减轻延迟治疗RHT-PA所加剧的缺血性神经元损伤。拟议中的实验就是为了检验这些假设。利用磁共振成像(MRI)和三维激光扫描共聚焦显微镜(LSCM)技术，我们将首先研究短期、大剂量阿托伐他汀对脑血管通畅性和完整性的影响，包括脑血流量(CBF)和血脑屏障漏出，以及tPA的神经毒性作用。利用激光捕获显微切割结合实时定量聚合酶链式反应、Western印迹分析和阻断PI3-K/Akt激活的特异性抑制剂，我们将深入探讨PI3K/Akt信号通路介导血栓形成和血脑屏障漏相关内皮细胞基因表达以及参与tPA神经毒性作用的神经元基因表达的机制。这些研究将有助于全面了解他汀类药物延长急性缺血性卒中溶栓窗口的作用机制，并可能为人类缺血性卒中提供一种新的有用的治疗策略。

DESCRIPTION (provided by applicant): Approximately 80-90% of human cerebral ischemic events are caused by thromboembolism. There is a compelling need to develop acute therapeutic interventions for the treatment of stroke. We present preliminary data indicating that atorvastatin, a hydroxymethylglutaryl coenzyme A reductase inhibitor, extends the therapeutic window of thrombolysis in a rat model of embolic stroke by activation of the PI3- K/Akt signaling pathway. However, the atorvastatin mediated therapeutic effect is independent of eNOS and lipid levels. The goals of this application are to determine the efficacy of statins in combination with thrombolysis for treatment of acute ischemic stroke and to investigate mechanisms underlying the therapeutic effects of atorvastatin as an adjuvant agent to recombinant human tissue plasminogen activator (rht-PA). Our hypotheses are: 1) Treatment of stroke with atorvastatin in combination with rht-PA extends the therapeutic window for acute stroke; 2) Atorvastatin activates the PI3-K/Akt signaling transduction pathway in cerebral endothelial cells, which decreases cerebral microvascular thrombosis and blood brain barrier (BBB) leakage by negatively regulating endothelial cell genes that promote thrombogenicity, vascular permeability, and inflammation; 3) Activation of the PI3-K/Akt cell survival pathway in neurons by atorvastatin attenuates ischemic neuronal damage exacerbated by delayed treatment of rht-PA. The proposed experiments have been designed to test these hypotheses. Using Magnetic Resonance Imaging (MRI) and 3D laser scanning confocal microscopy (LSCM) techniques, we will first investigate the effects of short-term, high-dose atorvastatin on cerebral vascular patency and integrity including cerebral blood flow (CBF) and BBB leakage, and the neurotoxic effects of tPA. Using laser capture microdissection in combination with real time PCR, Western blot analysis and specific inhibitors which block PI3-K/Akt activation, we will then delve into the mechanisms by which the PI3K/Akt signaling pathway mediates expression of endothelial cell genes involved in thrombosis and BBB leakage, and expression of neuronal genes engaged in the neurotoxic effects of tPA. These studies will lead to a comprehensive understanding of mechanisms underlying the therapeutic effects of statins on extending the window of thrombolysis for acute ischemic stroke and may provide a novel and useful treatment strategy for human ischemic stroke.