Microglial and macrophage PGE2 signaling in post-stroke inflammation

描述（由申请人提供）：卒中是一个多阶段的过程，初始缺血阶段之后是继发性损伤和卒中后炎症的修复，这些损伤和修复会在较长时间内展开。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，因此卒中后炎症反应代表了卒中进展中的预防性可达阶段，其中干预可以改善功能恢复。髓系细胞，特别是常驻小胶质细胞和浸润性巨噬细胞，在中风后执行重要和有益的功能，包括清除毒性碎片和生长和抗炎因子的加工;然而，这些细胞也可以产生毒性活性氧，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具有有益的但也有毒性作用。在最近的研究中，检查PGE 2 EP 2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，髓系EP 2信号传导的细胞特异性消融在体内是显著有益的，并且减少毒性炎症，增强免疫细胞运输和有毒物质的清除，并导致先天性免疫炎症模型中营养因子的产生。由于中风后早期炎症阶段表现出先天免疫反应的许多特征，我们假设中风后，小胶质细胞和巨噬细胞EP 2信号传导将呈现相似的特征，并且在这种情况下，髓样细胞中的EP 2消融将通过增强对有毒碎片的吞噬作用和产生有益的营养因子而具有显著和有益的效果。在这个提议中，我们将使用一种经过验证的条件性基因敲除方法来选择性地消融巨噬细胞和小胶质细胞中的EP 2，以及药理学策略来测试这些假设。我们将测试中风后炎症性EP 2信号的失活是否可以增强和加速功能恢复。这些研究将有助于我们进一步了解脑卒中后小胶质细胞-巨噬细胞的生物学特性，并验证针对脑卒中后EP 2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.