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

基本信息

批准号：
10212469
负责人：
Joshua Daniel Crapser
金额：
$ 4.29万
依托单位：
UNIVERSITY OF CALIFORNIA-IRVINE
依托单位国家：
美国
项目类别：
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/10212469
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 aggregation reconstitution therapeutic target virtual

项目摘要

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.

项目概要/摘要亨廷顿病 (HD) 是一种常染色体显性遗传疾病，由扩展的 CAG 重复序列组成亨廷顿基因的外显子 1 异常延长的聚谷氨酰胺束，导致亨廷顿蛋白突变。蛋白 (mHTT) 促进错误折叠和多种病理性 mHTT 种类的积累。大脑中 mHTT 聚集导致进行性纹状体和皮质神经元损失、运动功能障碍、认知障碍和最终的小胶质细胞激活在临床发病前几年就很明显。与其他神经退行性疾病中的症状类似，它们被认为对疾病做出反应在神经退行性状态下，小胶质细胞会对检测到的神经元变性和损伤做出反应。长期分泌促炎细胞因子、活性氧和其他损伤造成的损伤介质，所有这些都加剧了疾病进展。 HD 不仅继发于神经元损伤，而且小胶质细胞中 mHTT 的存在本身也启动了这些细胞，导致基础促炎细胞因子产生和能力的自主上调然而，HD 领域的特点是缺乏对小胶质细胞体内功能作用的研究。我们实验室之前报道了集落刺激因子1的持续抑制。受体（CSF1R）消除了健康和疾病小鼠模型中全脑的小胶质细胞，而随后初步观察，撤回抑制剂会刺激中枢神经系统内源性小胶质细胞的重新增殖。研究中，我们发现 R6/2 转基因 HD 小鼠模型中 CSF1R 受到抑制，该模型表达突变的人类亨廷顿基因和非转基因小鼠消除了≥85%的小胶质细胞。通过改善或挽救一些与 HD 相关的行为缺陷以及减少多种症状的积累另外，我们的实验室最近发现 CSF1R 抑制剂治疗/停药。在骨髓嵌合小鼠中，其外周免疫系统受到辐射并用供体重建衍生细胞，刺激几乎所有天然小胶质细胞被浸润的供体来源的骨髓细胞替代重要的是，这使我们能够研究用骨髓细胞替代野生型大脑中的小胶质细胞的效果。来自任何转基因系的细胞，包括 HD 小鼠，因此，该提案旨在扩展我们对 HD 小鼠的研究结果。小胶质细胞在 HD 中的作用，方法是 1) 在 HD 长期 zQ175 小鼠模型中消除小胶质细胞 6 个月表达全长突变亨廷顿基因并评估与疾病相关的行为和行为的变化病理表型和 2) 利用骨髓嵌合体中的 CSF1R 抑制剂/戒断范例消除小胶质细胞，将 zQ175 小鼠来源的含有 mHTT 的骨髓细胞移植到野生型大脑中，并随后评估行为和神经活力的改变，这些数据将阐明。通过更相关的 HD 小鼠模型在临床中靶向 CSF1R 的治疗潜力并表征大脑中含有 mHTT 的骨髓细胞的自主效应（反作用效应）。