Genetic Control of Microglia and Neural Macrophages

项目描述（由申请人提供）：本项目将利用斑马鱼遗传学的力量，发现对小胶质细胞和神经巨噬细胞的发育、迁移和激活至关重要的新基因。小胶质细胞是中枢神经系统（CNS）内高度活跃的吞噬性胶质细胞，可破坏病原体并清除凋亡细胞和受损轴突等碎片。巨噬细胞在周围神经中具有类似的功能。在疾病或损伤后，小胶质细胞和巨噬细胞的不适当激活可引起神经系统损伤。例如，在多发性硬化症（MS）和其他中枢神经系统疾病中，激活的小胶质细胞释放细胞毒性因子，损害髓鞘轴突。同样，活化的巨噬细胞损伤糖尿病周围神经病变的髓鞘轴突。尽管小胶质细胞和巨噬细胞在健康和病变神经系统中的重要性，但在对这些细胞的发育、迁移和激活的理解方面存在根本性的差距。因此，研究调节小胶质细胞和神经巨噬细胞功能的机制将为神经系统疾病的病理生理学提供重要的见解，包括多发性硬化症、周围神经病变和许多其他疾病。此外，这些研究将为预防和修复神经系统损伤的治疗提供新的途径。为了发现对小胶质细胞和神经巨噬细胞的发育和功能至关重要的新基因，我们将对这些细胞被破坏的突变进行基因筛选。使用快速，强大的小胶质细胞和巨噬细胞标记试验，我们发现在我们之前的髓鞘突变体筛选中恢复的突变体中，小胶质细胞和巨噬细胞增加并强烈激活。有趣的是，一种阻断小胶质细胞和巨噬细胞活化的药物可以改善nsf突变体的表型，这表明活化的吞噬细胞有助于这些突变体的病理。这些结果证明了发现影响小胶质细胞和神经巨噬细胞的突变的可行性，也强调了髓鞘轴突与相关吞噬细胞之间关系的重要性。对具有异常小胶质细胞和巨噬细胞的其他突变体的分析将验证这些细胞的激活有助于神经系统的各种病理的假设，因此它们在不同情况下会加重或减轻症状。本项目将在小胶质细胞和巨噬细胞中分离出更多具有重要功能的基因突变，并在细胞和生化水平上表征这些基因的功能。这些实验将阐明脊椎动物神经生物学的基本方面，建立重要人类疾病的斑马鱼模型，增加对患病和受伤轴突中断过程的理解，并为追求神经系统损伤的治疗性修复提供基础。公共卫生相关性：巨噬细胞和小胶质细胞是免疫系统对抗感染的特化细胞，但这些细胞也会损害包括多发性硬化症、糖尿病和许多其他疾病在内的健康组织。该项目将发现控制小胶质细胞和巨噬细胞的新基因，这将阐明这些细胞在疾病中的作用，并推动寻找修复损伤或疾病引起的神经系统损伤的治疗方法。

DESCRIPTION (provided by applicant): This project will exploit the power of zebrafish genetics to discover new genes that are essential for the development, migration, and activation of microglia and neural macrophages. Microglia are highly motile, phagocytic glial cells within the central nervous system (CNS) that destroy pathogens and clear debris such as apoptotic cells and damaged axons. Macrophages perform similar functions in peripheral nerves. In disease or after injury, inappropriate activation of microglia and macrophages can cause damage to the nervous system. For example, in multiple sclerosis (MS) and other diseases in the CNS, activated microglia release cytotoxic factors that harm myelinated axons. Similarly, activated macrophages damage myelinated axons in diabetic peripheral neuropathy. Despite the importance of microglia and macrophages in the healthy and diseased nervous system, there are fundamental gaps in the understanding of the development, migration, and activation of these cells. Thus investigation of the mechanisms that regulate the function of microglia and neural macrophages will provide important insights into the pathophysiology of diseases of the nervous system, including MS, peripheral neuropathies, and many others. In addition, these studies will suggest new avenues toward therapies to prevent and repair damage to the nervous system. To discover new genes essential for the development and function of microglia and neural macrophages, we will conduct a genetic screen for mutations in which these cells are disrupted. Using a rapid, robust marker assay for microglia and macrophages, we have found that microglia and macrophages are increased and strongly activated in a mutant recovered in our previous screens for myelination mutants, nsf. Interestingly, a drug that blocks activation of microglia and macrophages ameliorates the phenotype of nsf mutants, suggesting that activated phagocytes contribute to pathology in these mutants. These results demonstrate the feasibility of finding mutations that affect microglia and neural macrophages, and also underscore the importance of the relationship between myelinated axons and the associated phagocytes. Analysis of additional mutants with abnormal microglia and macrophages will test the hypothesis that activation of these cells contributes to diverse pathologies of the nervous system, such that they act to exacerbate and ameliorate symptoms in different contexts. This project will isolate more mutations in genes with essential functions in microglia and macrophages and characterize the functions of these genes at the cellular and biochemical level. These experiments will elucidate fundamental aspects of vertebrate neurobiology, establish zebrafish models of important human diseases, add to the understanding of the processes that are disrupted in diseased and injured axons, and provide a basis to pursue the therapeutic repair of damage to the nervous system. PUBLIC HEALTH RELEVANCE: Macrophages and microglia are specialized cells of the immune system that fight infection, but these cells can also damage healthy tissue in diseases including multiple sclerosis, diabetes, and many others. This project will discover new genes that control microglia and macrophages, which will illuminate the roles these cells play in disease and advance the search for therapies to repair damage to the nervous system caused by injury or disease.