Ifi27l2a as a therapeutic target for stroke

摘要 小胶质细胞(MG)是大脑的固有免疫细胞，在炎症反应中发挥关键作用。 卒中。中风主要影响老年人。不幸的是，随着年龄的增长，MG变得越来越多 功能失调，与大脑中的其他细胞类型一起，导致中风后更糟糕的结果。 然而，MG在中风脑中的作用并不完全是坏的，因为MG也有助于修复和恢复 中风后。因此，老年人特定时间段MG炎症反应的选择性调节 大脑对中风患者可能有很大的治疗价值。 利用单细胞转录分析(ScRNAseq)，我们发现了一个基因(干扰素α诱导蛋白 27样蛋白2a；Ifi27l2a)，在老年性MG中选择性地高度上调，并在 卒中后的镁。我们的初步分析显示，Ifi27l2a的表达与特异性 促炎症细胞因子和衰老相关基因的集合。这些研究和其他研究表明， Ifi27l2a可能在促进MG卒中后炎症反应中起关键调节作用 小白鼠的大脑。对人脑样本的分析也显示IFI27L2(人类亚型)的表达增加 在中风脑中，增强了我们发现的翻译相关性。接下来，为了定义Ifi27l2a的功能角色， 我们进行了体外和体内研究的结合，这建立了一个令人信服的致病作用 IFI27l2a在促进MG促炎功能和加重卒中损伤中的作用。我们还建立了 Ifi27l2a过表达可能诱导基质金属蛋白酶的表达/活性和反应性 氧物种(ROS)的产生，这是血脑屏障(BBB)破坏的两个驱动因素。最后， 使用小鼠中风模型，我们发现Ifi27l2a(Ifi27l2a+/-小鼠)的部分缺失导致显著 改善预后，表现为梗死体积缩小和小胶质细胞活化减少。加在一起，这些 数据为IFI27l2a在调节MG功能和卒中后脑损伤中提供了第一个直接证据 并将Ifi27l2a依赖的信号转导作为新的治疗靶点。 我们提出的目标将检验总体假设，即增加MG Ifi27l2a有助于夸大 老年脑缺血性卒中的炎症反应及降低MG IFI27l2a的表达 减轻神经炎症，减少血脑屏障破坏，改善中风后的预后。如果成功，这些 研究将为基于选择性减弱MG促炎作用的新策略奠定基础 治疗中风或其他与神经炎性疾病相关的信号。

Abstract Microglia (MG), the resident innate immune cells of the brain, play a critical role in the inflammatory response to stroke. Stroke predominantly affects older individuals. Unfortunately, with aging, MG become increasingly dysfunctional and, in conjunction with other cell types in the brain, contribute to worse outcome following stroke. However, the role of MG in the stroke brain is not exclusively bad, as MG also contribute to repair and recovery following stroke. Thus, the selective regulation of the MG inflammatory response at specific times in the aged brain could be of great therapeutic value for stroke patients. Using single-cell transcriptomic analysis (scRNAseq), we discovered a gene (interferon alpha-inducible protein 27-like protein 2A; Ifi27l2a) that was selectively and highly upregulated in aged MG and further upregulated in MG following stroke. Our initial analysis showed a positive correlation between Ifi27l2a expression and specific sets of pro-inflammatory cytokine and senescence-related genes. These and other studies suggested that Ifi27l2a might play a critical regulatory role in promoting the inflammatory response of MG in the post-stroke brain of mice. Analysis of human brain samples also showed increased expression of IFI27L2 (human isoform) in stroke brain, enhancing the translational relevance of our findings. Next, to define the functional role of Ifi27l2a, we performed a combination of in vitro and in vivo studies, which established a compelling causative role of Ifi27l2a in promoting MG proinflammatory function and in worsening stroke injury. We also established the potential for Ifi27l2a overexpression to induce matrix metalloproteinase (MMP) expression/activity and reactive oxygen species (ROS) production, which are two driving factors in blood brain barrier (BBB) disruption. Finally, using a mouse stroke model, we showed that partial deletion of Ifi27l2a (Ifi27l2a+/- mice) led to significantly improved outcome, as evidenced by reduced infarct volume and reduced microglial activation. Together, these data provide the first direct evidence for Ifi27l2a in modulating MG functionality and brain injury following stroke and establish Ifi27l2a-dependent signaling as a new therapeutic target. Our proposed aims will test the overall hypothesis that increased MG Ifi27l2a contributes to an exaggerated inflammatory response to ischemic stroke in the aged brain and that reducing MG Ifi27l2a expression can attenuate neuroinflammation, reduce BBB disruption, and improve outcome following stroke. If successful, these studies will lay the foundation for a novel strategy based on the selective attenuation of MG pro-inflammatory signaling in the treatment of stroke or other pathologies associated with neuroinflammation.