Endogenous and exogenous protection of the BBB in stroke

描述(申请人提供)：中风时血脑屏障的内源性和外源性保护。血脑屏障(BBB)功能障碍可见于多种神经系统疾病和损伤(如中风)。这种功能障碍可能通过促进白细胞流入大脑，允许潜在的神经毒性血液成分进入，并导致血管源性水肿来参与这些状态。此外，它还可能影响疾病的治疗(例如，出血性转化是使用组织型纤溶酶原激活剂诱导的再灌注疗法治疗缺血性中风的主要限制因素)。因此，迫切需要各种方法来保护血脑屏障。治疗靶点可能通过检查哪些内源性机制在疾病状态下发生变化来确定。我们已经证明，在体内和体外，预适应刺激对血脑屏障和脑内皮细胞具有保护作用。我们还发现，中风相关因素导致脑血管内皮细胞内谷胱甘肽的调节因子--半胱氨酸/谷氨酸交换系统(系统XC-)的表达显著增加。这种交换受Nrf2(一种抗氧化剂转录因子)的调节，而Xc-可以被萝卜硫素显著上调，萝卜硫素是Nrf2的激活剂，也是十字花科蔬菜的一种成分。这些结果使我们假设：Nrf2及其调控的蛋白质(例如XCT、血红素加氧酶1和铁蛋白)可能是保护血脑屏障的靶标。由于Nrf2对这些蛋白质的调节需要蛋白质合成，我们还假设该系统的功能是防止延迟的BBB破坏，特别是由于缺血时白细胞的迁移。这些假说将在五个具体目标中进行检验：1+2)确定中风相关因子、炎症介质或萝卜硫素上调系统XC-是否具有保护性。3+4)确定NRF2在中风或炎症后是否在脑内皮细胞中被激活，以及它的激活和下游蛋白的上调是否对脑内皮细胞具有保护作用。5)观察萝卜硫素对体内血脑屏障的保护作用。这些特定的目标将在体外进行检查，以便阐明分子机制，并在体内确定病理生理学相关性。结果应突出内源性血脑屏障保护机制和潜在的外源性化合物激活或抑制这些机制。与公共卫生相关：脑血管具有非常特殊的功能，形成血脑屏障。这一屏障的破坏发生在许多神经疾病和损伤中，导致大脑功能障碍。这项提案研究了可能保护血脑屏障的自然防御机制，以及如何激活这些机制或从疗法上防止它们失活。

DESCRIPTION (provided by applicant): Endogenous and exogenous protection of the BBB in stroke. Blood-brain barrier (BBB) dysfunction occurs in a wide variety of neurological diseases and injuries (e.g. stroke). Such dysfunction may participate in those states by enhancing the influx of leukocytes into the brain, allowing the entry of potentially neurotoxic blood components and causing vasogenic edema. In addition, it may affect disease treatment (e.g. hemorrhagic transformation is a major limiting factor for the use of tissue plasminogen activator-induced reperfusion therapy for ischemic stroke). There is, therefore, a great need for methods to protect the BBB. Therapeutic targets may potentially be identified by examining which endogenous mechanisms are altered in disease states. We have shown that preconditioning stimuli can protect the BBB and cerebral endothelial cells in vivo and in vitro. We have also shown that stroke-related factors cause a marked increase in the expression of the cystine/glutamate exchanger (system xc-), a regulator of intracellular glutathione, in cerebral endothelial cells. This exchanger is regulated by nrf2 (an anti-oxidant transcription factor) and xc- can be markedly upregulated by exposure to sulforaphane, an activator of Nrf2 and a component of cruciferous vegetables. These results have led us to hypothesize that: Nrf2 and the proteins it regulates (e.g. xCT, heme oxygenase 1 and ferritin) may be a target for protecting the BBB. As Nrf2 regulation of these proteins requires protein synthesis, we also hypothesize that the function of this system is to protect against delayed BBB disruption, particularly due to migrating leukocytes in ischemia. These hypotheses will be examined in five specific aims: 1+2) Determine whether upregulation of system xc- by stroke-related factors, inflammatory mediators or sulforaphane is protective. 3+4) Determine whether Nrf2 is activated in the cerebral endothelium after stroke or inflammation and whether its activation and the upregulation of downstream proteins will protect the cerebral endothelium. 5) Examines whether treatment with sulforaphane can protect the BBB in vivo. These specific aims will be examined in vitro, to allow elucidation of molecular mechanisms, and in vivo, to determine pathophysiological relevance. The results should highlight endogenous BBB protective mechanisms and the potential exogenous compounds to activate or inhibit those mechanisms. PUBLIC HEALTH RELEVANCE: Brain blood vessels have very specialized functions, forming a blood-brain barrier. Disuption of that barrier occurs in many neurological disorders and injuries, contributing to brain dysfunction. This proposal examines natural defense mechanisms that may protect the blood-brain barrier, how to activate those mechanisms or prevent their inactivation therapeutically.