DNA damage-induced inflammation and its brain-specific consequences

摘要 神经退行性疾病，如阿尔茨海默氏病和帕金森氏病，代表了一组不同的疾病， 条件虽然脑细胞的损失是最突出的表型，但每种疾病也都表现为 慢性炎症过程的证据拟议的工作将探讨一个新认识到的触发这一点 毒性神经炎症过程，细胞质DNA（cytoDNA）。先天免疫系统的细胞， cGAS/STING和TLR 9将细胞DNA的存在解释为入侵的病毒或细菌病原体， 积极回应。在衰老和神经退行性疾病中，细胞应激导致DNA释放 从细胞自身的线粒体或核基因组的片段进入细胞质，引发“不育” 炎症反应。干扰素相关基因和NFκB系统被动员，两者都引起了严重的 如果他们的反应变得慢性化，无菌性炎症的研究传统上集中在 先天免疫系统（例如，小胶质细胞）或辅助细胞如星形胶质细胞。我们建议采取更大的 更广泛的方法，通过单独测试大脑中的每种细胞类型在促进慢性疾病中的作用， 阿尔茨海默氏症和帕金森氏症的炎症。我们将跟踪核能和核能的相对贡献， 线粒体片段与细胞DNA总量之比。作为应激源，我们将使用ATM抑制， 修复，TFAM抑制损伤线粒体，以及更多的疾病相关刺激，如Aβ， 阿尔茨海默病和帕金森病的α-突触核蛋白。我们预测线粒体的贡献 细胞核DNA片段在不同的情况下会有所不同，导致独特的TLR 9和cGAS/STING 这些反应导致临床症状多样性的签名分泌组。测试 每种细胞DNA刺激的免疫反应的病理潜能，我们将使用不同的刺激来挑战 星形胶质细胞、神经元、少突胶质细胞和小胶质细胞的培养物。然后我们将收集它们的条件培养基 并在相同细胞类型的原始培养物上进行测试，以分离出所有有毒和营养元素， 从不同的细胞中释放出来。受刺激细胞的转录组将由RNAseq定义;蛋白质转录组将由RNAseq定义。 分泌物组的组成将通过LC/MS确定。虽然我们的初步研究将在培养的细胞中进行，但我们 将使用三种不同神经退行性疾病的小鼠模型在体内验证体外研究结果： 老年痴呆症帕金森症和共济失调毛细血管扩张症最后，我们建议制定多管齐下的战略， 阻断细胞DNA诱导的炎症的影响。我们将寻找能阻止 从细胞核中释放细胞DNA或刺激其从细胞质中消除。研究结果的重要性 源于这样一个事实，即了解无菌炎症的过程以及如何阻止它将提供新鲜的 改善我们治疗许多神经退行性疾病的方法的策略。

Abstract Neurodegenerative diseases such as Alzheimer's and Parkinson's disease represent a diverse group of conditions. While the loss of brain cells is the most prominent phenotype, each disease also presents with evidence of a chronic inflammatory process. The proposed work will explore a newly recognized trigger of this toxic neuroinflammatory process, cytoplasmic DNA (cytoDNA). The cells of the innate immune system, using cGAS/STING and TLR9, interpret the presence of cytoDNA as an invading viral or bacterial pathogen and respond vigorously. In aging and neurodegenerative diseases, cellular stresses lead to the release of DNA fragments from the cell's own mitochondrial or nuclear genome into the cytoplasm, triggering a "sterile" inflammatory response. Interferon related genes and the NFκB system are mobilized and both cause great harm if their responses become chronic. Studies of sterile inflammation traditionally focus on the cells of the innate immune system (e.g., microglia), or accessory cells such as astrocytes. We propose to take a much broader approach, by separately testing each cell type in the brain for its role in contributing to the chronic inflammation found in Alzheimer's and Parkinson's. We will track the relative contributions of nuclear and mitochondrial fragments to the total amount of cytoDNA. As stressors, we will use ATM inhibition, to block DNA repair, TFAM inhibition to damage mitochondria, as well as more disease-relevant stimuli such as Aβ for Alzheimer's disease and α-synuclein for Parkinson's disease. We predict that the contributions of mitochondrial and nuclear cytoDNA fragments will differ in different situations, resulting in unique TLR9 and cGAS/STING responses that result in a signature secretome that contributes to the diversity of clinical symptoms. To test the pathological potential of each cytoDNA-stimulated immune response, we will use different stimuli to challenge cultures of astrocytes, neurons, oligodendrocytes and microglia. We will then collect their conditioned medium and test it on naïve cultures of the same cell types to isolate the full range of toxic and trophic elements released from different cells. The transcriptomes of the stimulated cells will be defined by RNAseq; the protein composition of the secretome will be determined by LC/MS. While our initial studies will be in cultured cells, we will validate the in vitro findings in vivo using mouse models of three distinct neurodegenerative diseases: Alzheimer's, Parkinson's and ataxia-telangiectasia. Finally, we propose to develop a multi-pronged strategy to block the impact of cytoDNA-induced inflammation. We will search for compounds that block the export of cytoDNA from the nucleus or stimulate its elimination from the cytoplasm. The significance of the findings derives from the fact that understanding the process of sterile inflammation and how to block it will offer fresh strategies to improve our approach to many neurodegenerative diseases.