Neuroinflammatory Mechanisms in the Progression of Parkinson's Disease

描述（由申请人提供）：神经炎症正在成为许多慢性神经退行性疾病（包括肌萎缩性侧索硬化症、阿尔茨海默病、多发性硬化症和帕金森病）的神经退行性过程中的中心病理生理学介质。特别是，与帕金森病进展有关的神经炎症机制是目前的研究焦点，因为线粒体功能障碍和氧化应激不能完全解释黑质纹状体多巴胺能系统的慢性退行性进展，最终导致不可逆的衰弱性运动缺陷。有趣的是，帕金森病大脑的尸检分析揭示了炎症过程的迹象，包括小胶质细胞活化和促炎因子如TNF α和NF-κ B的诱导，沿着黑质中多巴胺能神经元的损失。同样，最近的证据从帕金森氏病的实验模型清楚地表明，在黑质纹状体区的小胶质细胞活化和细胞因子释放暴露于神经毒性损伤。然而，在神经毒性损伤过程中调节小胶质细胞中神经炎症级联反应的细胞事件以及小胶质细胞介导的炎症在黑质变性过程进展中的作用尚未完全了解。如在初步数据中所描述的，我们已经确定了新的PKC亚型家族的成员，蛋白激酶C-δ（PKCd），作为从小胶质细胞释放关键促炎细胞因子TNF α的关键调节剂。我们还证明，激酶也作为一个促凋亡激酶在多巴胺能神经元在炎症损伤。（i）使用帕金森病的细胞培养模型确定PKCd在神经元和小胶质细胞中活化的差异模式，并检查PKCd在调节促炎细胞因子（例如，TNF α）; ii）使用帕金森氏病的动物模型来检查PKCd在黑质纹状体多巴胺能系统中的细胞因子产生和小胶质细胞活化中的作用; iii）确定神经炎性细胞因子是否上调小胶质细胞中PKCd的表达以维持和放大NF-κ B依赖性方式的炎性级联反应;和iv）确定来自小胶质细胞的神经炎性反应是否可以在帕金森病的动物模型中通过PKCd的蛋白水解活化诱导黑质多巴胺能神经元的变性。这些具体的目标将探索使用各种细胞和分子生物学方法在帕金森氏病的神经炎症模型。这种系统的方法将有助于解开关键的分子机制，调节小胶质细胞中的神经炎症级联在帕金森氏病的黑质多巴胺能神经元的进行性变性。最终，这些机制研究将转化为这种渐进性衰弱性神经退行性疾病的创新治疗干预措施。公共卫生相关性：帕金森病是一种慢性和进行性神经退行性疾病，影响全球数百万人。黑质多巴胺能神经元进展过程中的细胞机制尚不清楚。这项建议的重点是蛋白激酶亚型特异性细胞信号通路，可能发挥作用，在黑质纹状体系统的小胶质细胞的神经炎症级联放大。了解负责黑质变性进展的促炎事件的细胞机制将最终导致治疗策略的发展，这将延迟或停止帕金森病的进程。

DESCRIPTION (provided by applicant): Neuroinflammation is emerging as a central pathophysiological mediator in the neurodegenerative processes of many chronic neurodegenerative disorders including amyotrophic lateral sclerosis, Alzheimer's disease, multiple sclerosis, and Parkinson's disease. In particular, neuroinflammatory mechanisms pertaining to the progression of Parkinson's disease are current focal points of investigation since mitochondrial dysfunction and oxidative stress can not completely explain the chronic degenerative progression in the nigrostriatal dopaminergic system that ultimately results in irreversible debilitating motor deficits. Interestingly, postmortem analysis of the Parkinson's disease brain reveals signs of inflammatory processes including microglial activation and induction of proinflammatory factors such as TNFa and NF-kB along with loss of dopaminergic neurons in the nigra. Similarly, recent evidence from experimental models of Parkinson's disease clearly demonstrates microglial activation and cytokine release in the nigrostriatal region during exposure to neurotoxic insults. However, the cellular events which regulate the neuroinflammatory cascade in microglia during neurotoxic insults and the role of microglia mediated inflammation in the progression of nigral degenerative processes are not completely understood. As depicted in the preliminary data, we have identified a member of the novel PKC isoform family, protein kinase C-delta (PKCd), as a critical regulator of release of a key proinflammatory cytokine TNFa from microglial cells. We also demonstrated that the kinase also serves as a proapoptotic kinase in dopaminergic neurons during inflammatory insults. In this proposal, we will extend our preliminary findings by pursuing the following specific aims: (i) To determine the differential mode of activation of PKCd in neuronal and microglial cells using cell culture models of Parkinson's disease and to examine the role of PKCd in regulating the production of proinflammatory cytokines (e.g., TNFa) in microglial cells; ii) To examine the role of PKCd in cytokine production and microglial activation in the nigrostriatal dopaminergic system using animal models of Parkinson's disease; iii) To determine whether neuroinflammatory cytokines upregulate the expression of PKCd in microglia to sustain and amplify the inflammatory cascade in a NF-kB dependent manner; and iv) To determine whether neuroinflammatory response from microglia can induce degeneration of nigral dopaminergic neurons through proteolytic activation of PKCd in animal models of Parkinson's disease. These specific objectives will be explored using various cellular and molecular biological approaches in neuroinflammatory models of Parkinson's disease. This systematic approach will help to unravel the key molecular mechanisms that regulate the neuroinflammatory cascade in microglia during the progressive degeneration of nigral dopaminergic neurons in Parkinson's disease. Ultimately, these mechanistic studies will translate into innovative therapeutic interventions for this progressively debilitating neurodegenerative disorder. PUBLIC HEALTH RELEVANCE: Parkinson's disease is a chronic and progressive neurodegenerative disorder affecting millions worldwide. The cellular mechanisms underlying the course of progression of nigral dopaminergic neurons is not yet understood. This proposal focuses on a protein kinase isoform specific cell signaling pathway that might play a role in amplification of the neuroinflammatory cascade in microglial cells in the nigrostriatal system. Understanding the cellular mechanisms of proinflammatory events responsible for progression of nigral degeneration will ultimately result in development of therapeutic strategies that will delay or halt the course of Parkinson's disease.