Neuroinflammatory Mechanisms in the Progression of Parkinson's Disease

描述(申请人提供)：神经炎是许多慢性神经退行性疾病，包括肌萎缩侧索硬化症、阿尔茨海默病、多发性硬化症和帕金森氏病的神经退化过程中的中心病理生理介质。特别是，与帕金森病进展相关的神经炎性机制是目前研究的重点，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，最终导致不可逆转的衰弱运动障碍。有趣的是，帕金森病脑的尸检分析揭示了炎症过程的迹象，包括小胶质细胞的激活和促炎因子如TNFa和NF-kB的诱导，以及黑质中多巴胺能神经元的丢失。同样，帕金森病实验模型的最新证据清楚地表明，在暴露于神经毒性侮辱时，黑质纹状体区域的小胶质细胞激活和细胞因子释放。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退变过程中的作用尚不完全清楚。如初步数据所示，我们已经确定了新的PKC亚型家族的一个成员，即蛋白激酶C-增量(PKCd)，它是从小胶质细胞释放关键的促炎细胞因子TNFa的关键调节因子。我们还证明，在炎性损伤期间，该激酶也可以作为多巴胺能神经元中的促凋亡激酶。在这个提案中，我们将通过追求以下具体目标来扩展我们的初步发现：(I)利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的不同激活模式，并研究PKCd在调节小胶质细胞中促炎症细胞因子(如TNFa)的产生中的作用；ii)利用帕金森病的动物模型，研究PKCd在黑质纹状体多巴胺系统中细胞因子产生和小胶质细胞激活中的作用；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，以维持和放大依赖于NF-kB的炎症级联反应；以及iv)在帕金森病动物模型中，确定小胶质细胞的神经炎性反应是否可以通过蛋白水解性激活PKCd来诱导黑质多巴胺能神经元的变性。这些特定的目标将在帕金森氏病的神经炎性模型中使用不同的细胞和分子生物学方法来探索。这一系统的方法将有助于揭示帕金森病黑质多巴胺能神经元进行性变性过程中调节小胶质细胞神经炎性级联反应的关键分子机制。最终，这些机械性研究将转化为这种渐进性神经退行性疾病的创新治疗干预措施。公共卫生相关性：帕金森氏症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的细胞机制尚不清楚。这项建议侧重于蛋白激酶异构体的特定细胞信号通路，该通路可能在黑质纹状体系统的小胶质细胞的神经炎性级联放大中发挥作用。了解导致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，从而延缓或阻止帕金森氏病的进程。

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.