Investigating the Role of Microglia in Huntington’s Disease

研究小胶质细胞在亨廷顿病中的作用

• 批准号: 9760991
• 负责人: Joshua Daniel Crapser
• 金额: $ 4.05万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9760991
• 关键词: Adverse effects; Affect; Animal Behavior; Appearance; Behavior; Behavioral; Bone Marrow; Brain; CAG repeat; Cause of Death; Cells; Cessation of life; Chimera organism; Chronic; Clinic; Clinical; Corpus striatum structure; Data; Disease; Disease Progression; Distress; Dominant Genetic Conditions; Etiology; Excision; Exons; Genes; Genetic Diseases; Health; Human; Huntington Disease; Huntington gene; Huntington protein; Immune; Immune system; Impaired cognition; Inflammatory; Length; Light; Macrophage Colony-Stimulating Factor Receptor; Mediating; Mediator of activation protein; Methods; Microglia; Modeling; Mus; Myeloid Cells; Nerve Degeneration; Neuraxis; Neurodegenerative Disorders; Neuronal Injury; Neurons; Pathogenesis; Pathologic; Patients; Peripheral; Phenotype; Physiological; Production; Proteins; Reactive Oxygen Species; Receptor Inhibition; Regimen; Reporting; Research; Role; Secondary to; Source; Symptoms; Therapeutic; Transgenic Organisms; Transplantation; Treatment Efficacy; Treatment Protocols; Up-Regulation; Withdrawal; brain cell; brain volume; cell type; clinically relevant; cytokine; human disease; in vivo; inhibitor/antagonist; insight; motor disorder; motor symptom; mouse model; mutant; nerve injury; neuroinflammation; neuron loss; polyglutamine; protein aggregate; reconstitution; therapeutic target; virtual

Project Summary/Abstract Huntington’s disease (HD) is an autosomal dominant genetic disorder consisting of an expanded CAG repeat in exon 1 of the huntingtin gene. The abnormally elongated polyglutamine tract that results in the mutant huntingtin protein (mHTT) promotes misfolding and the accumulation of multiple pathologic mHTT species. The presence of mHTT aggregates in the brain leads to progressive striatal and cortical neuronal loss, motor dysfunction, cognitive disturbances, and eventual death. Activated microglia are evident years before the onset of clinical symptoms and, similar to their function in other neurodegenerative diseases, are thought to react to disease- associated neuronal degeneration and damage. In neurodegenerative states, microglia respond to detected damage by chronically secreting pro-inflammatory cytokines, reactive oxygen species, and other damage mediators, all of which exacerbate disease progression. Interestingly, neuroinflammatory effects of microglia in HD are not only secondary to neuronal damage, but the presence of mHTT in microglia itself primes these cells, leading to an autonomous upregulation of basal pro-inflammatory cytokine production and capacity to cause neuronal injury. However, the HD field is marked by a paucity of research on the in vivo functional role of microglia in disease pathogenesis. Our lab previously reported that the sustained inhibition of colony-stimulating factor 1 receptor (CSF1R) eliminates microglia brain-wide in murine models of both health and disease, while subsequent withdrawal of the inhibitor stimulates repopulation of microglia from CNS-endogenous sources. In a preliminary study, we found that CSF1R inhibition in the R6/2 transgenic HD mouse model, which expresses exon 1 of the mutant human huntingtin gene, and nontransgenic mice eliminated ≥ 85% of microglia. This was accompanied by an amelioration or rescue of several HD-associated behavioral deficits and a reduced accumulation of multiple species of mHTT in the brain. Separately, our lab recently discovered that CSF1R inhibitor treatment/withdrawal in bone marrow chimeric mice, whose peripheral immune system was irradiated and reconstituted with donor- derived cells, stimulates the replacement of virtually all native microglia with infiltrating donor-derived myeloid cells. Importantly, this allows us to investigate the effects of replacing microglia in the wild-type brain with myeloid cells from any transgenic line, including HD mice. Therefore, this proposal aims to extend our findings on the role of microglia in HD by 1) eliminating microglia for 6 months in the long-term zQ175 mouse model of HD expressing a full-length mutant huntingtin gene and assessing changes in disease-associated behavioral and pathological phenotypes and 2) utilizing the CSF1R inhibitor/withdrawal paradigm in bone marrow chimeras to eliminate microglia, transplant zQ175 mouse-derived mHTT-containing myeloid cells into wild-type brains and subsequently assess alterations in behavior and neuronal viability. Together, this data will elucidate the therapeutic potential of targeting CSF1R in the clinic with a more relevant mouse model of HD and characterize the autonomous, as opposed to reactionary, effects of mHTT-containing myeloid cells in the brain.

项目摘要/摘要 亨廷顿氏病（HD）是一种常染色体显性遗传疾病，由扩展的CAG重复组成 亨廷顿基因的外显子1。绝对伸长的聚谷氨酰胺道，导致突变体亨廷顿 蛋白质（MHTT）促进了多种病理MHTT物种的错误折叠和积累。存在 大脑中的MHTT聚集体会导致进行性纹状体和皮质神经元丧失，运动功能障碍， 认知障碍和最终死亡。活化的小胶质细胞是临床发作前几年的证据 症状，与其他神经退行性疾病中的功能类似，被认为对疾病的反应 相关的神经元变性和损害。在神经退行性状态下，小胶质细胞对检测到的反应 长期分泌促炎细胞因子，活性氧和其他损害损害 介体，所有这些都加剧了疾病的进展。有趣的是，小胶质细胞在 HD不仅是神经元损伤继发的，而且小胶质细胞中MHTT的存在本身就是这些细胞的素质， 导致基本促炎细胞因子产生的自主上调和引起的能力 神经元损伤。但是，HD场的标志性是对小胶质细胞的体内功能作用的缺乏。 在疾病发病机理中。我们的实验室先前报道说，持续抑制菌落刺激因子1 受体（CSF1R）在健康和疾病的鼠模型中消除了脑室的小胶质细胞，而随后 抑制剂的戒断刺激了来自中枢神经系统源源源的小胶质细胞的重生。在初步 研究，我们发现R6/2转基因HD小鼠模型中的CSF1R抑制作用，该模型表达了外显子1 突变的人亨廷汀基因和非转基因小鼠消除了≥85％的小胶质细胞。这是完成的 通过改善或营救几种与HD相关的行为定义的，多个的积累降低 大脑中的MHTT物种。另外，我们的实验室最近发现CSF1R抑制剂治疗/戒断 在骨髓嵌合小鼠中，其外周免疫系统被照射并用供体重构 衍生的细胞，刺激用浸润供体衍生的髓样的几乎所有天然小胶质细胞替换 细胞。重要的是，这使我们能够研究用髓样的野生型大脑中的小胶质细胞的影响 来自任何转基因线的细胞，包括HD小鼠。因此，该建议旨在将我们的发现扩展到 小胶质细胞在HD中的作用1）在长期的ZQ175小鼠模型中消除小胶质细胞6个月 表达全长突变体狩猎基因并评估与疾病相关的行为和 病理表型和2）在骨髓嵌合体中使用CSF1R抑制剂/戒断范式 消除小胶质细胞，移植ZQ175小鼠衍生的含MHTT的髓样细胞到野生型大脑中 随后评估行为和神经元生存力的改变。在一起，此数据将阐明 使用更相关的HD小鼠模型靶向CSF1R的治疗潜力 与大脑中含有MHTT的髓样细胞的反动作用相比，自主的作用。