ILC2s Polarize Microglia to a Reparative, M2-Like Phenotype

项目摘要：中风是美国第五大死亡原因，主要影响老年人 人FDA批准的治疗被证明是不够的，因为许多患者不适合再灌注 这些药物不能治疗继发性脑损伤或帮助脑修复。最有前途的疗法之一 针对中风的是具有调节作用的外周和中枢神经系统免疫反应 在中风病理学的各个阶段。衰老通过全面抑制免疫系统中的 免疫系统，包括细胞因子介质的失调，导致全身炎症增加 系统，称为炎症。然而，了解健康老龄化的机制可以绕过这种影响。 两种候选免疫细胞（1）小胶质细胞，脑内巨噬细胞，和（2）先天性淋巴细胞，一种新的免疫细胞。 发现的先天免疫细胞，可能控制中风前和中风后的反应在老年人的大脑。小胶质 免疫监视大脑的动态平衡，一旦检测到损伤就迅速启动。不幸的是他们 受炎症的影响，导致它们在抗炎反应方面很差，特别是在脑 损伤第2组先天淋巴样细胞（ILC 2）是调节小胶质细胞反应的主要候选细胞，因为它们 在损伤期间产生抗炎细胞因子（IL-4、IL-5和IL-13）。这些细胞因子调节 小胶质细胞修复表型，通过上调 愈合蛋白质，如血红素氧合酶1、血管内皮生长因子α。的 巨噬细胞和ILC 2之间的通讯已经在肾缺血的外周进行了研究， 再灌注损伤，但很少脑和老化。初步数据显示，随着年龄的增长，ILC 2在 与其他ILC类型相比，雄性和雌性小鼠的大脑。此外，男性在全球范围内增加了数倍， 总ILC和ILC 2计数的百分比，表明其总ILC和ILC 2计数大于女性。此外，雄性ILC 2 产生更多的细胞因子，在衰老过程中比女性具有更强的抗炎能力。最后，年轻的ILC 2 可溶性因子增加体外小胶质细胞中Nrf 2和Nrf 2调节基因。这意味着年老的ILC 2 可能有益于炎症反应期间的小胶质细胞极化。因此，我假设ILC 2 是大脑的守门人，在以下情况下将小胶质细胞极化为修复性M2样表型：（1）稳态 条件下，（2）缺血性损伤，和（3）与老化。在目的1中，我将研究ILC 2s和ILC 2的转录组 可溶性因子对小胶质细胞极化的影响。在目标2中，我将确定ILC 2对氧-葡萄糖的反应 剥夺，缺血性损伤的体外模型，以及它们的可溶性因子如何使启动的小胶质细胞极化。最后， 在目标3中，我将进行一个“概念验证”实验，以探讨离体刺激的ILC 2在老年人中的作用。 使用皮质内注射GFP+ ILC 2通过过继细胞转移小胶质细胞。加在一起，我将有 定义了ILC 2可溶性因子将小胶质细胞转化为修复性表型的能力。这将提供 进一步探索ILC 2作为中风和其他神经系统疾病的可能治疗平台的基本原理。

Project Summary: Stroke is the fifth leading cause of death in the United States, predominantly affecting aged people. FDA approved treatments are proving inadequate as many patients are ineligible for reperfusion therapies and they fail to treat secondary brain injury or help in brain repair. One of the most promising therapies for stroke is targeting the peripheral and central nervous system immune responses that have modulatory roles during all stages of stroke pathobiology. Aging affects immunologic responses by a global suppression of the immune system, including dysregulation of cytokine mediators, leading to increased inflammation throughout all systems, termed inflammaging. However, understanding mechanisms of healthy aging can bypass this effect. Two candidate immune cells (1) microglia, brain-resident macrophages, and (2) innate lymphoid cells, a newly discovered innate immune cell, may control pre- and post-stroke responses in the aged brain. Microglia immunosurveil the brain during homeostasis and are quickly primed once injury is detected. Unfortunately, they are affected by inflammaging causing them to be poor at anti-inflammatory responses, especially after brain injury. Group 2 innate lymphoid cells (ILC2s) are a prime candidate in regulating microglial responses as they produce anti-inflammatory cytokines (IL-4, IL-5, and IL-13) during times of injury. These cytokines modulate microglia to a reparative phenotype by increasing their trophic and phagocytic capacity through upregulation of healing proteins like heme oxygenase 1, arginase 1, and vascular endothelial growth factor alpha. The communication between macrophages and ILC2s have been investigated peripherally in kidney ischemic- reperfusion injury, but very little brain and in aging. Preliminary data show that with age, ILC2s increase in the brain of male and female mice compared to other ILC types. Moreover, males have a multi-fold global increase of total ILC and ILC2 counts putting their total ILC and ILC2 counts greater than females. Also, male ILC2s produce more cytokines and have a greater anti-inflammatory capacity in aging than females. Lastly, young ILC2 soluble factors increase Nrf2 and Nrf2-regulated genes in microglia in vitro. This would suggest that aged ILC2s could be beneficial in microglia polarization during inflammatory responses. Therefore, I hypothesize that ILC2s are the brain’s gatekeepers of microglia polarization to a reparative, M2-like phenotype under: (1) homeostatic conditions, (2) ischemic insult, and (3) with aging. In Aim 1, I will investigate the transcriptome of ILC2s and ILC2 soluble factors on microglia polarization. In Aim 2, I will identify the response of ILC2s to oxygen-glucose deprivation, an in vitro model of ischemic injury, and how their soluble factors polarize primed microglia. Lastly, in Aim 3, I will perform a “proof-of-concept” experiment to inquire the role of ex-vivo stimulated ILC2s on aged microglia via adoptive cell transfer using intracortical injections of GFP+ ILC2s. Taken together, I will have defined the capacity of ILC2 soluble factors to polarize microglia to a reparative phenotype. This will provide the rationale to further explore ILC2 as a possible therapeutic platform in stroke and other neurologic disorders.