Microglial and macrophage PGE2 signaling in post-stroke inflammation

描述（由申请人提供）：中风是一个多阶段的过程，最初的缺血阶段之后是继发性损伤和中风后炎症的修复，这一过程持续了很长一段时间。由于针对神经保护和脑血流的策略具有狭窄的有效时间窗口，因此卒中后炎症反应代表了卒中演变过程中可翻译的阶段，干预可能会改善功能恢复。髓系细胞，特别是常驻小胶质细胞和浸润性巨噬细胞，在中风后发挥重要和有益的功能，包括清除有毒碎片和阐明生长和抗炎因子；然而，这些细胞也能产生有毒的活性氧、细胞因子和蛋白酶。因此，小胶质细胞和巨噬细胞在中风后可能有有益的作用，但也可能有毒性作用。在最近的研究中，我们检查了PGE2 EP2受体在小胶质细胞和巨噬细胞中的体内功能，我们已经确定细胞特异性消融髓系EP2信号在体内是显著有益的，可以减少毒性炎症，增强免疫细胞运输和清除有毒物质，并导致先天免疫炎症模型中营养因子的细化。由于中风后早期炎症期表现出许多先天免疫反应的特征，我们假设中风后，小胶质细胞和巨噬细胞的EP2信号传导将具有相似的特征，在这种情况下，骨髓细胞中EP2的消融将通过增强毒性碎片的吞噬和产生有益的营养因子而产生显著而有益的效果。在本提案中，我们将使用一种经过验证的条件敲除遗传方法来选择性地切除巨噬细胞和小胶质细胞中的EP2，以及药理学策略来验证这些假设。我们将测试脑卒中后炎性EP2信号失活是否可以增强和加速功能恢复。本研究将有助于提高我们对脑卒中后小胶质-巨噬细胞生物学的认识，并验证脑卒中后针对EP2信号通路的新方法。

DESCRIPTION (provided by applicant): Stroke is a multiphasic process, and the initial ischemic phase is followed by secondary injury and repair from post-stroke inflammation that unfolds over an extended time period. Because strategies targeting neuroprotection and cerebral blood flow have a narrow time window of efficacy, the post-stroke inflammatory response represents a translationally accessible phase in stroke evolution where intervention may improve functional recovery. Myeloid-lineage cells, notably resident microglia and infiltrating macrophages, perform important and beneficial functions after stroke, including clearance of toxic debris and elaboration of growth and anti-inflammatory factors; however, these cells also can produce toxic reactive oxygen species, cytokines, and proteases. Therefore, microglia and macrophages can have beneficial but also toxic effects after stroke. In recent studies examining the in vivo function of the PGE2 EP2 receptor in microglia and macrophages, we have determined that cell-specific ablation of myeloid-lineage EP2 signaling is significantly beneficial in vivo, and reduces toxic inflammation, enhances immune cell trafficking and clearance of toxic substances, and leads to elaboration of trophic factors in models of innate immune inflammation. Because the early post-stroke inflammatory phase exhibits many of the characteristics of an innate immune response, we hypothesize that post-stroke, microglia and macrophage EP2 signaling will assume similar characteristics, and ablation of EP2 in myeloid cells in this setting will have significant and beneficial effects by enhancing phagocytosis of toxic debris and generating beneficial trophic factors. In this proposal, we will use a validated conditional knockout genetic approach to selectively ablate EP2 in macrophages and microglia as well as pharmacological strategies to test these hypotheses. We will test whether functional recovery can be enhanced and accelerated with inactivation of inflammatory EP2 signaling post stroke. The proposed studies should help advance our understanding of microglial-macrophage biology post-stroke, and validate new approaches targeting EP2 signaling pathway after stroke.