Role of Hypoxia Inducible Factor-1 in Inflammation

描述(由申请人提供)：发生在缺血后血管中的生物过程通常会引发内源性炎症系统失效，引发血管和实质器官损伤。低氧诱导因子-1(HIF-1)是一种异二聚体蛋白，由低氧激活的血管内皮细胞中的α和β亚基组成，调节细胞在缺血环境中生存所必需的基因(即诱导型一氧化氮合酶和血红素加氧酶-1)的表达。到目前为止，很少有研究确定HIF-1在调节缺血后血管中发生的炎症事件中的作用。导致提交这一修订申请的新研究表明，HIF-1α亚单位的稳定显著减少了缺血后兔和小鼠心脏的梗塞面积和中性粒细胞的渗透，在我们的研究中，IL-8(一种与缺血后血管损伤和器官损伤持续相关的促炎趋化因子)显著地被HIF-1激活抑制。体外人微血管内皮细胞实验表明，HIF-1直接在转录水平上调节IL-8的分泌，或通过分别诱导一氧化氮合酶和血红素加氧酶-1基因后产生一氧化氮(NO)和一氧化碳(CO)间接调节IL-8的分泌。我们假设：缺氧诱导因子-1单独或与关键效应基因协同作用，调节复氧微血管内皮细胞趋化因子的表达。本研究的目的有四个：(1)确定HIF-1激活在抑制缺血/再灌流后心脏趋化因子生成中的作用；(2)研究NO和CO在调节再给氧微血管内皮细胞IL-8表达中的相互依赖性；(3)评价HIF-1在HO-1诱导的IL-8生成中的作用；(4)确定IL-8启动子与HIF-1结合在微血管内皮细胞中的功能意义。这里提出的研究将产生大量的新知识，建立HIF-1作为调节炎症事件的关键分子。此外，这项工作的结果将开启了解趋化因子诱导的炎症调节的新时代，并允许合理设计专门针对减轻缺血后血管损伤的工具。

DESCRIPTION (provided by applicant): Biological processes occurring in post-ischemic vasculature commonly initiate events that produce failure of endogenous inflammatory systems, precipitating vascular and parenchymal organ injury. Hypoxia Inducible Factor-1 (HIF-1), a heterodimeric protein consisting of alpha and beta subunits activated in vascular endothelium during hypoxia, modulates expression of genes essential for cell survival (i.e., inducible nitric oxide synthase and heme oxygenase-1) in ischemic environments. Little research to date has established a role for HIF-1 in modulating inflammatory events that occur in post ischemic vasculature. New research leading to submission of this revised application reveals that stabilization of the alpha subunit of HIF-1 dramatically reduces infarct size and polymorphonuclear neutrophil infiltration in post-ischemic rabbit and murine hearts, lnterleukin-8 (IL-8), a pro-inflammatory chemokine consistently associated with post-ischemic vascular injury and organ damage was strikingly repressed by HIF-1 activation in our studies. In vitro experiments using human microvascular endothelial cells suggest that HIF-1 modulates secretion of IL-8 acting directly at a transcriptional level or indirectly through generation of nitric oxide (NO) and carbon monoxide (CO) following induction of nitric oxide synthase and heme oxygenase-1 (HO-1) genes respectively. We hypothesize that: Hypoxia inducible factor-1 acting independently or in concert with key effector genes regulates chemokine expression in reoxygenating microvascular endothelium. Four aims are proposed in this application: (1) To determine the role of HIF-1 activation in attenuation of cardiac chemokine generation following ischemia/reperfusion; (2) To examine molecular interdependency between NO and CO in regulation of IL-8 expression in reoxygenating microvascular endothelium; (3) To evaluate the role of HIF-1 in modulating HO-1-induced IL-8 generation; (4) To determine the functional significance of IL-8 promoter binding by HIF-1 in microvascular endothelium. The research proposed here will produce substantial new knowledge, establishing HIF-1 as a pivotal molecule in modulation of inflammatory events. Further, the results of this work will open a new era of understanding of the regulation of chemokine induced inflammation and permit the rational design of tools targeted specifically to attenuate post-ischemic vascular injury.