Targeting Complement Component 3 in a Model of Synucleinopathy

突触核蛋白病模型中的靶向补体成分 3

• 批准号: 10191978
• 负责人: Matthew John Benskey
• 金额: $ 35.21万
• 依托单位: MICHIGAN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-01 至 2023-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10191978
• 关键词: Astrocytes; Autopsy; Brain Diseases; Cells; Complement; Complement 3; Complement Activation; Complex; Corpus striatum structure; Deposition; Disease; Disease model; Excision; Gene Expression; Genetic; Glial Fibrillary Acidic Protein; Goals; Injections; Innate Immune System; Label; Lewy Bodies; MicroRNAs; Microglia; Midbrain structure; Modeling; Morphology; Names; Nerve Degeneration; Neuraxis; Neurodegenerative Disorders; Neurons; Parkinson Disease; Pathogenesis; Pathologic; Pathology; Pathway interactions; Phagocytes; Play; Positron-Emission Tomography; Process; Rattus; Recombinant adeno-associated virus (rAAV); Recombinants; Reporting; Research; Role; Signal Transduction; Substantia nigra structure; Synapses; Testing; Time; Toxic effect; Validation; alpha synuclein; astrogliosis; cell type; complement pathway; complement system; dopaminergic neuron; experimental study; human disease; imaging study; immunogenic; insight; neuroinflammation; nigrostriatal system; novel; pars compacta; pathogen; pre-formed fibril; prevent; promoter; protein aggregation; protein expression; response; synucleinopathy; targeted treatment; virtual

PROJECT SUMMARY Parkinson's Disease (PD) is a complex and progressive neurodegenerative disorder that culminates in the deposition of alpha synuclein (a-syn) containing protein aggregates, named Lewy bodies, and the degeneration of nigrostriatal dopamine neurons. Evidence suggests that neuroinflammation plays a causative role in the pathogenesis of PD. Post-mortem- and longitudinal PET imaging studies of the PD brain reveal an increase in the number of activated microglia that occur early in the disease process and remain elevated throughout the course of the disease. Activated microglia can convert astrocytes to a subtype of toxic “A1- astrocyte” and these reactive astrocytes are observed in the PD brain. A1 astrocytes coordinate selective neurodegeneration by releasing components of the complement system. The complement system is a division of the innate immune system that coordinates the removal of pathogens and cell debris. However, the complement system, and specifically complement component 3 (C3), is also used by the central nervous system to tag vulnerable synapses and neurons for phagocytic clearance. Within the PD brain, toxic A1- astrocytes dramatically increase the expression of C3. Taken together, we hypothesize that following an initial immunogenic signal (pathological a-syn misfolding) C3 derived from A1 astrocytes is used to tag inclusion-containing neurons for destruction by microglia. Supporting this idea, both midbrain dopamine neurons and Lewy bodies label with activated C3 in the PD brain. Neuroinflammation has been reported with virtually every model of PD. However the majority of PD models fail to accurately recapitulate the defining features of PD pathology: The progressive aggregation of endogenous a-syn and subsequent degeneration of nigrostriatal neurons. In contrast, intrastriatal injection of recombinant a- syn pre-formed fibrils (PFFs) is able to accurately model these hallmarks of PD pathology, and a neuroinflammatory response that mimics the human disease. We have extensively characterized this model and found that injection of a-syn PFFs into the rat striatum results in peak a-syn aggregate formation within the substantia nigra pars compacta (SNc) at 2 months post-injection, followed by significant nigral degeneration by 6 months. During the peak of a-syn aggregation we observe peak microglial activation as well as robust astrogliosis. Genetic expression and morphological profiling of reactive astrocytes is consistent with the presence of toxic A1-astrocytes. As such we hypothesize that C3 derived from A1 reactive astrocytes is used to tag inclusion-containing nigral neurons for destruction. Supporting this idea, we observe a large increase in the expression of C3 during this time point, and have localized C3 to reactive astrocytes. Importantly, the presence of toxic A1-astrocytes and the increase in C3 expression occurs months prior to overt nigral degeneration, suggesting astrocytic C3 may play a role in the degenerative process. Thus, preventing release or activation of C3 may prevent the degeneration induced by a-syn aggregation. In the present exploratory R21 application we propose to both characterize and directly test the role of the complement system in the neurodegeneration induced following synucleinopathy. The overarching hypothesis of this application is that C3 derived from A1-astrocytes, following a-syn aggregation, acts to coordinate the selective degeneration of nigral neurons.

项目摘要 帕金森病（PD）是一种复杂的进行性神经退行性疾病，其最终表现为 含有α-突触核蛋白（α-syn）的蛋白质聚集体（称为路易体）的沉积，以及 黑质纹状体多巴胺神经元的变性。有证据表明，神经炎症是 在PD发病机制中的作用。PD脑的死后和纵向PET成像研究显示， 在疾病过程的早期出现并保持升高的活化小胶质细胞数量增加 在疾病的整个过程中。活化的小胶质细胞可以将星形胶质细胞转化为有毒的“A1- 这些反应性星形胶质细胞在PD脑中观察到。A1星形胶质细胞选择性协调 通过释放补体系统的成分而引起神经变性。补体系统是一个分裂 先天免疫系统的一部分，协调病原体和细胞碎片的清除。但 补体系统，特别是补体成分3（C3），也被中枢神经系统所使用。 系统来标记脆弱的突触和神经元，以进行吞噬清除。在PD大脑中，有毒的A1- 星形胶质细胞显著增加C3的表达。综上所述，我们假设， 来源于A1星形胶质细胞的初始免疫原性信号（病理性a-syn错误折叠）C3用于标记 内含物的神经元被小胶质细胞破坏。支持这一观点的是， 在PD脑中，神经元和路易体用活化的C3标记。 几乎每种PD模型都报告了神经炎症。然而，大多数PD模型失败 为了准确地概括PD病理学的定义特征： a-syn和随后的黑质纹状体神经元变性。相反，纹状体内注射重组a- 合成预成形纤维（PFF）能够准确地模拟PD病理学的这些标志， 模拟人类疾病的神经炎症反应。我们已经广泛地描述了这个模型 并发现将a-syn PFF注射到大鼠纹状体中导致在纹状体内形成峰值a-syn聚集体。 注射后2个月，黑质丘脑部（SNc）发生显著的黑质变性， 6个月在a-syn聚集的峰值期间，我们观察到峰值小胶质细胞活化以及鲁棒的 星形胶质细胞增生反应性星形胶质细胞的遗传表达和形态学特征与 存在毒性A1-星形胶质细胞。因此，我们假设使用来自A1反应性星形胶质细胞的C3 标记含有内含物的黑质神经元进行破坏。为了支持这一观点，我们观察到， C3的表达在这个时间点，并已定位C3的反应性星形胶质细胞。重要的是 毒性A1-星形胶质细胞的存在和C3表达的增加发生在明显的黑质细胞分化之前几个月。 变性，表明星形胶质细胞C3可能在变性过程中发挥作用。从而防止 C3的释放或激活可以防止由α-syn聚集诱导的变性。 在目前的探索性R21应用中，我们建议同时表征和直接测试 补体系统在突触核蛋白病引起的神经变性中的作用总体 本申请的假设是来源于A1-星形胶质细胞的C3在α-syn聚集后， 来协调黑质神经元的选择性退化。