Vascular Mechanisms of Cerebral Ischemic Tolerance

脑缺血耐受的血管机制

• 批准号: 6967502
• 负责人: JEFFREY M GIDDAY
• 金额: $ 38.25万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6967502
• 关键词: apoptosis; cerebral ischemia /hypoxia; cerebrovascular system; cytoprotection; disease /disorder model; gene expression; human tissue; ischemic preconditioning; laboratory mouse; microcirculation; nitric oxide synthase; protein structure function; stroke; survivin; tissue /cell culture; transcription factor; vascular endothelium

DESCRIPTION (provided by applicant): Vascular dysfunction and vascular injury, as manifested by impairments in microvascular perfusion, autoregulation, and vascular reactivity, as well as by vasogenic edema, hemorrhage, inflammation, and coagulation, contribute importantly to outcome following focal stroke. Treatment strategies may derive from studies of "ischemic tolerance", wherein endogenous mechanisms of protection are activated by different "preconditioning" stimuli. Studies outlined in this proposal will focus on elucidating the innate mechanisms responsible for protection of cerebrovascular endothelium following hypoxic preconditioning, utilizing a mouse model of induced tolerance to focal stroke and a human cerebrovascular endothelial cell culture model of ischemic tolerance, both developed and characterized in our laboratory. Key induction and expression mechanisms whereby hypoxic preconditioning attenuates diverse endpoints of ischemia-induced vascular/endothelial dysfunction and injury will be elucidated in each model. Specific Aim 1: Elucidate the role of endothelial nitric oxide synthase (eNOS) in the induction and expression pathways responsible for hypoxic preconditioning-induced cerebrovascular ischemic tolerance in vivo and in vitro. We hypothesize that eNOS-derived NO is integral to the signaling pathways responsible for inducing the transcription/translation of vasculoprotective genes. We also hypothesize that eNOS is an effector protein contributing to the ischemia-tolerant phenotype of the preconditioned cerebral microcirculation. Specific Aim 2: Delineate the involvement of the transcription factor HIF-2alpha in mediating cytoprotective gene expression in endothelial cells in vivo and in vitro in response to hypoxic and chemical preconditioning. We will test the hypothesis that the activity of HIF-2alpha, highly expressed in endothelial cells, is upregulated by these preconditioning stimuli, is modulated by eNOS-derived NO and phosphorylated Akt, and is critical to mediating the expression of cytoprotective genes in endothelium that lead to ischemic tolerance. Specific Aim 3: Elucidate the participation of survivin, a specific inhibitor-of-apoptosis family member, in the resistance of in vivo- and in vitro-preconditioned endothelium to ischemic injury, and the mechanisms by which this protein affords protection. We hypothesize that hypoxic preconditioning upregulates survivin expression, which blocks caspase-mediated endothelial injury, thereby preserving post-ischemic microcirculatory homeostasis. Identification of endogenous mechanisms of endothelial cell resistance to ischemic injury may provide novel molecular targets for the therapeutic treatment of vascular dysfunction and vascular injury following focal stroke.

描述（由申请人提供）：血管功能障碍和血管损伤，表现为微血管灌注、自身调节和血管反应性受损，以及血管源性水肿、出血、炎症和凝血，对局灶性卒中后的预后有重要影响。治疗策略可能源于“缺血耐受”的研究，其中内源性保护机制被不同的“预处理”刺激激活。本研究将重点阐明缺氧预处理后脑血管内皮保护的先天机制，利用小鼠局灶性卒中诱导耐受模型和人脑血管内皮细胞培养缺血耐受模型，这两种模型都是在我们的实验室开发和表征的。缺氧预处理减轻缺血诱导的血管/内皮功能障碍和损伤的不同终点的关键诱导和表达机制将在每个模型中阐明。