Inflammatory Mechanisms in Cerebral Ischemia

描述（由申请人提供）：中风是这个国家死亡和残疾的重要原因。治疗方法很少，而且只有一小部分中风患者能得到治疗。我们和其他人已经证明应激诱导的70 kDa热休克蛋白（HSP70）具有神经保护作用。脑缺血事件后的保护机制尚不清楚，但主要归因于其伴侣功能，其中HSP70通过阻止蛋白质聚集来改善细胞存活。最近的一些研究表明，HSP70也可能具有抗炎特性。目前已知炎症通过急性脑组织损伤参与脑缺血损伤，但HSP70是否在脑卒中中发挥抗炎作用尚不清楚。在本研究中，我们将探讨选择性HSP70过表达在脑缺血和缺血样损伤中调节炎症反应的作用。在完整的大脑中，这种反应似乎是由驻留的小胶质细胞和入侵的外周白细胞介导的。炎症细胞产生潜在的有害物质，如活性氧和活性氮、细胞因子、趋化因子、谷氨酸和各种蛋白酶。使用HSPT0组成性过表达的转基因小鼠模型，我们将首先在一个具有良好特征的中风模型中验证HSP70与炎症反应减少相关的假设。通过混合培养神经元、星形胶质细胞和小胶质细胞，我们观察到小胶质细胞增加了缺血样损伤的损伤。因此，我们将研究小胶质细胞中选择性过表达HSP70是否可以逆转恶化的损伤，并探索这一观察结果背后的潜在机制，如抑制炎症介质和抑制炎症转录因子核因子κ B （NFkB）。在最后的目标中，我们将使用骨髓嵌合体研究外周炎症细胞在小鼠中风模型中的参与，其中野生型动物移植来自HSP70转基因小鼠的骨髓细胞。这些研究应该为HSP70保护脑缺血和脑缺血样损伤的新机制提供独特的见解。

DESCRIPTION (provided by applicant): Stroke is a significant cause of death and disability in this country. Treatments are few and available to only a small percentage of stroke victims. We and others have shown that the stress inducible 70 kDa heat shock protein (HSP70) is neuroprotective. The mechanism of protection following cerebral ischemic events is not well known, but has largely been attributed to its chaperone functions whereby HSP70 improves cell survival by preventing protein aggregation. A few recent studies suggest that HSP70 may also have antiinflammatory properties. It is now known that inflammation participates in cerebral ischemic injury by contributing to brain tissue damage acutely, but it is unknown whether HSP70 plays an anti-inflammatory role in stroke. In this proposal, we will explore the effects of selective HSP70 overexpression in regulating the inflammatory response in brain ischemia and ischemia-like insults. In the intact brain, this response appears to be mediated by both the resident microglia and invading peripheral leukocytes. Inflammatory cells produce potentially damaging substances such as reactive oxygen and nitrogen species, cytokines, chemokines, glutamate and various proteases. Using a transgenic mouse model where HSPT0 is constitutively overexpressed, we will first test the hypothesis that HSP70 is associated with a reduction in this inflammatory response in a well characterized stroke model. Using mixed cultures of neurons, astrocytes and microglia, we have observed that microglia increase damage to ischemia-like insults. Therefore, we will examine whether selective overexpression of HSP70 in microglia may reverse the worsened injury, and explore potential mechanisms behind this observation such as suppression of inflammatory mediators and inhibition of the inflammatory transcription factor, nuclear factor kappa B (NFkB). In the final aim, we will then study the participation of peripheral inflammatory cells in a mouse stroke model using bone marrow chimeras, where wildtype animals are transplanted with marrow cells derived from the HSP70 transgenic mice. These studies should provide uniqae insights into a new mechanism by which HSP70 may protect against injury following cerebral ischemic and ischemia-like insults.