What do microglia do? Dissecting their function in CNS health and disease

描述(申请人提供)：小胶质细胞做什么？小胶质细胞是大脑中髓系衍生的居留细胞，可以对大脑和周围的病理事件产生免疫反应。最近，我们和其他人已经确定了小胶质细胞在中枢神经系统的生理过程中的作用，例如在发育过程中突触的消除。然而，无法可靠地区分小胶质细胞和密切相关的髓系细胞，混淆了许多关于小胶质细胞在健康和疾病中的功能的报道。因此，我们寻找了一种蛋白质标记物，可以可靠地识别、靶向和鉴定小胶质细胞。我根据我们广泛的细胞特异性基因表达阵列进行筛选，并通过原位杂交证实了TM119就是这样一个标记。在这个应用中，我将测试这样一个假设，即小胶质细胞的一部分被“交替激活”，这意味着在激活时，它们限制炎症并促进组织修复，而这些小胶质细胞限制中枢神经系统的损伤。然后我将测试选择性丢失的小胶质细胞是否会阻碍中枢神经系统的修复。在第一个目标中，我将表征TM119在整个发育过程中的表达，并测试一种基于TM119的工具，TM119/CreERT2 BAC转基因小鼠，以遗传靶向小胶质细胞。在第二个目的中，我将使用这只小鼠来专门防止小胶质细胞的替代激活，并检查这对视神经挤压伤后损伤严重程度的影响。在最终目标中，我将使用 白喉毒素与TM119/CreERT2小鼠一起靶向小胶质细胞，以确定它们是否对中枢神经系统修复和神经保护是必需的。这些研究有可能首次剖析和理解小胶质细胞在中枢神经系统损伤和修复中的具体作用。 公共卫生相关性：这项建议旨在研究CNS神秘的免疫细胞-小胶质细胞-及其在损伤反应和修复中的作用，这将为神经疾病的机制和潜在的治疗靶点提供洞察。

DESCRIPTION (provided by applicant): What do microglia do? Microglia are myeloid-derived residents of the brain that can mount immune responses to pathologic events in the brain and periphery. Recently, we and others have identified roles for microglia in physiologic processes of the CNS, such as in synapse elimination during development. However, the inability to reliably distinguish microglia from closely related myeloid cells confounds many reports of microglial function in health and disease. Therefore, we sought out a protein marker that would allow the reliable identification, targeting, and characterization of microglia. I identified TM119 as such a marker by a screen based on our extensive cell specific gene expression arrays and confirmed with in situ hybridization. In this application, I will test the hypothesis that a subset of microglia are "alternatively activated", meaning that upon activation they limit inflammation and promote tissue repair, and that these microglia limit CNS injury. I wil then test if selective loss of microglia hinders CNS repair. In the first aim, I will characterize TM119 expression throughout development and test a TM119-based tool, a TM119/CreERT2 BAC transgenic mouse, to genetically target microglia. In the second aim, I will use this mouse to specifically prevent alternative activation of microglia and examine the effect of this on injur severity following crush injury to the optic nerve. In the final aim, I will ablate microglia using Diphtheria toxin targeted to microglia with the TM119/CreERT2 mouse to determine if they are required for CNS repair and neuroprotection. These studies have the potential to dissect and understand, for the first time, the specific contribution of microglia to CNS injury and repair. PUBLIC HEALTH RELEVANCE: This proposal aims to study the mysterious immune cells of the CNS-microglia-and their role in injury response and repair, which will provide insight into mechanisms of neurological disease and potential therapeutic targets.