Neurovascular Protection for Early Brain Injury after SAH

描述(申请人提供)：在我们之前的授权期(蛛网膜下腔出血的神经血管保护，NIH/NS053407 2007-2011)中，我们研究了针对脑血管痉挛和脑水肿的内皮保护机制。我们的研究是开创性的观察结果，早期脑损伤的特征是颅内压升高，脑血流量减少，脑灌注压降低，血脑屏障破坏，脑水肿增加，零星分布的神经细胞死亡/凋亡，从而导致SAH后72小时内神经功能评估不佳，而不是我们以前认为的脑血管痉挛，是决定临床结果的因素。我们的观察引领了SAH研究方向的变化，世界上大多数实验室现在都在研究早期脑损伤处理以改善结果。在我们之前的研究中，我们已经确定了几种有希望的蛛网膜下腔出血(SAH)后神经血管保护的候选药物，其中之一是骨桥蛋白(OPN)。OPN是一种细胞外基质蛋白，可通过其精氨酸-甘氨酸-天冬氨酸(RGD)序列与细胞表面整合素受体相互作用，参与促进细胞存活、增殖和减少细胞凋亡。我们实验室和其他实验室最近的研究表明，在各种临床前卒中模型中，脑室内注射重组骨桥蛋白(ROPN)对神经血管具有保护作用。然而，rOPN诱导神经血管保护的机制尚未得到评估。阐明OPN发挥作用的分子机制将有助于开发预防SAH的新疗法。此外，我们建议鼻内给予rOPN，这是一种公认的、安全的、非侵入性的绕过血脑屏障的方法。本研究的具体目的是确定rOPN作为一种新的治疗策略对SAH后早期脑损伤的神经血管保护作用，并探讨rOPN通过抗细胞凋亡信号和稳定血脑屏障发挥神经血管保护的机制。我们的中心假设是鼻腔给药rOPN通过整合素受体信号通路减少神经元的凋亡和稳定血脑屏障，从而对SAH后的早期脑损伤起到保护作用。为了解决我们的假设，我们提出了以下三个具体目标。目的1确定蛛网膜下腔出血后鼻腔给药rOPN的神经血管保护作用。我们的具体假设是：(1)鼻腔注射rOPN后，脑脊液/脑组织中OPN浓度升高。(2)rOPN通过整合素受体信号通路改善SAH后的神经功能，降低死亡率。目的2探讨rOPN抗蛛网膜下腔出血后细胞凋亡的作用机制。我们的具体假设是：(1)rOPN通过FAK信号途径和(2)通过PI3K/Akt通路进行抗细胞凋亡信号转导。目的3探讨rOPN对蛛网膜下腔出血后血脑屏障的保护机制。我们的具体假设是，rOPN通过ILK和RAC-1途径保护BBB。这项建议的长期目标是为rOPN的临床翻译提供基础，作为一种有效的治疗选择，以预防SAH患者的并发症，并改善长期患者的整体预后。

DESCRIPTION (provided by applicant): In our previous grant period (Neurovascular Protection for Subarachnoid Hemorrhage, NIH/NS053407 2007- 2011) we have studied endothelial protective mechanisms against cerebral vasospasm and brain edema. Our studies were the pioneering observations that early brain injury which is featured by an elevated intracranial pressure, reduced cerebral blood flow, decreased cerebral perfusion pressure, disrupted blood-brain barrier, increased brain edema, sporadically distributed neuronal cell death/apoptosis, and therefore resulted poor neurological functional evaluations within 72 hrs after SAH, is a determination factor, rather than cerebral vasospasm as we believed previously, for clinical outcome. Our observations lead the changes of the directions of SAH research, and most labs in the world are now studying early brain injury management to improve outcomes. During our previous studies, we have identified several promising candidates for neurovascular protection after subarachnoid hemorrhage (SAH) and one of them is osteopontin (OPN). OPN is an extracellular matrix protein that can interact with cell surface integrin receptors through its arginine-glycine- aspartate (RGD) sequence and has been implicated in promoting cell survival, proliferation and reducing cellular apoptosis. Recent studies from our laboratory and others have demonstrated the neurovascular protective effects of intracerebroventricular administration of recombinant osteopontin (rOPN) in various preclinical stroke models. However, the mechanism by which rOPN elicits neurovascular protection has not been evaluated. Elucidating the molecular mechanisms by which OPN exerts its effects would facilitate the development of a novel therapy to protect against SAH. Furthermore, we propose to administer rOPN intranasally, which is an established, safe, and non-invasive method to bypass the blood-brain barrier. The specific objective of this proposal is to determine the neurovascular protective potential of rOPN administered intranasally as a novel treatment strategy to reduce early brain injury after SAH, and to determine the mechanism of neurovascular protection conferred by rOPN through anti-apoptotic signaling and BBB stabilization. Our central hypothesis is that intranasal administration of rOPN provides protection against early brain injury after SAH by reducing neuronal apoptosis and stabilization of the BBB via integrin receptor signaling pathway. The following three specific aims are proposed to address our hypothesis. Aim 1 will determine the neurovascular protective effect of intranasal rOPN administration after SAH. Our specific hypothesis is (1) that OPN concentration in CSF/brain will be increased after intranasal rOPN administration. (2) intranasal rOPN will improve neurological outcomes and reduce mortality after SAH via integrin receptor signaling. Aim 2 will determine the mechanism of anti-apoptotic effect of rOPN after SAH. Our specific hypothesis is that (1) rOPN performs anti-apoptotic signaling mediated by FAK signaling and (2) via PI3K/ Akt pathways. Aim 3 will determine the mechanism of blood brain barrier protection by rOPN after SAH. Our specific hypothesis is that rOPN protects BBB via ILK and Rac-1 pathways. The long-term goal of this proposal is to provide a basis for clinical translation of rOPN as an effective therapeutic option o protect against complications in patients after SAH and to improve overall patient outcomes in the long-term.