Cyclooxygenase-2 Regulation of Blood-Brain Barrier Opening in Ischemic Stroke

描述（由申请人提供）：神经炎症导致缺血性脑卒中的进行性损害。缺血性脑卒中后24-48小时发生的血脑屏障（BBB）破坏是导致神经元死亡的病理机制。迫切需要确定限制卒中后继发损伤的药理学策略。环氧合酶(COX)-2/前列腺素E2 （PGE2）途径积极参与炎症事件，加剧初始缺血性脑损伤。我们的长期目标是了解COX-2/PGE2通路如何被操纵来阻止缺血性卒中后的进行性损伤级联。该项目的总体目标是确定COX-2/PGE2增加如何介导缺血性卒中中血脑屏障损伤和神经元死亡。我们的中心假设是，抑制COX-2/PGE2通路通过减少MMP-3/-9的产生来保护血脑屏障损伤和神经元死亡。这项拟议研究的基本原理是，了解COX-2/PGE2在中风中的急性（有害）和晚期（可能有益）作用的机制，应该通过阻断COX-2/PGE2途径的药物来确定更具选择性和有效的治疗干预的新靶点。特异性目的1：确定cox -2介导的MMP-3/-9表达/活性增加和缺血后血脑屏障损伤的下游效应物。本实验旨在验证cox -2来源的PGE2通过激活特异性EP受体诱导局灶性缺血性脑损伤中MMP-3/-9的产生和血脑屏障的破坏。我们将在一个建立良好的缺血性中风大鼠模型中使用体内药理学方法。这将与EP受体和MMP-3/-9的免疫组织化学、免疫印迹和生化分析相结合。特定目标#2：确定调节COX-2/PGE2途径的药物的保护治疗时间窗和长期效果。本研究的实验验证了这样一种假设，即用阻断缺血诱导的PGE2形成/信号传导的药物进行缺血后治疗可以提供神经保护，而不会干扰后期恢复阶段。我们将利用体内药理学方法，结合创新的MRI技术和一系列测试来评估神经功能。MRI方法将结合免疫组织化学分析来测量神经发生和血管生成。我们期望这项研究将为COX-2衍生的PGE2及其EP受体在缺血性中风后的神经炎症过程中的作用提供重要的知识。我们还希望确定针对COX- 2/PGE2的药物管理的临床相关治疗时间窗口。这样的结果有望产生重要的积极影响，因为它们将确定新的和急需的方法来减少中风引起的血脑屏障损伤的破坏性后果。

DESCRIPTION (provided by applicant): Neuroinflammation leads to progressive damage in ischemic stroke. Disruption of the blood-brain barrier (BBB) occurring at 24-48 h following ischemic stroke is a pathological mechanism that contributes to neuronal death. There is an urgent need to identify pharmacological strategies that limit the secondary damage following stroke. The cyclooxygenase (COX)-2/prostaglandin E2 (PGE2) pathway is actively involved in inflammatory events that exacerbate initial ischemic brain injury. Our long-term goal is to understand how the COX-2/PGE2 pathway can be manipulated to block the progressive injury cascade following ischemic stroke. The overall objective of this project is to determine how increased COX-2/PGE2 mediates BBB damage and neuronal death in ischemic stroke. Our central hypothesis is that inhibition of the COX-2/PGE2 pathway protects against BBB damage and neuronal death by reducing MMP-3/-9 production. The rationale for the proposed research is that understanding the mechanisms involved in acute (deleterious) and late (possibly beneficial) effects of COX-2/PGE2 in stroke should identify novel targets for a more selective and effective therapeutic intervention with drugs blocking the COX-2/PGE2 pathway. Specific Aim #1: To identify the downstream effectors of COX-2-mediated increase in MMP-3/-9 expression/activity and damage to the BBB after ischemia. Experiments in this aim test the hypothesis that COX-2-derived PGE2 induces MMP-3/-9 production and BBB breakdown through activation of specific EP receptor(s) in focal ischemic brain injury. We will utilize an in vivo pharmacological approach in a well- established rat model of ischemic stroke. This will be coupled with immunohistochemical, immunoblotting and biochemical analyses of EP receptors and MMP-3/-9. Specific Aim #2: To determine the therapeutic time window of protection and long-term effects of drugs modulating the COX-2/PGE2 pathway. Experiments in this aim test the hypothesis is that post- ischemic treatment with agents blocking ischemia-induced PGE2 formation/signaling provides neuroprotection without interfering in the late recovery phase. We will utilize an in vivo pharmacological approach together with innovative MRI techniques and a battery of tests to evaluate neurological function. The MRI approach will be coupled with immunohistochemical analyses to measure neurogenesis and angiogenesis. It is our expectation that this research will provide significant knowledge of the contribution of COX-2- derived PGE2 and its EP receptors to the neuroinflammatory process that follows ischemic stroke. We also expect to identify a clinically relevant therapeutic time window for the administration of drugs targeting COX- 2/PGE2. Such results would be expected to have an important positive impact, since they would identify novel and much-needed approaches to reduce the devastating consequences of stroke-induced BBB damage. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because the discovery of inflammatory mechanisms that exacerbate the injury in ischemic stroke will lead to the development of novel therapeutic strategies to significantly reduce the devastating consequences of stroke. Thus, this proposal is relevant to the part of NINDS's mission that pertains to developing significant knowledge in basic research that will create the foundation for treating ischemic stroke. This will help to reduce the burdens of this neurological disease.