Ischemic stroke is an acute cerebrovascular disease characterized by high mortality, morbidity and disability rates. Ischemia/reperfusion is a critical pathophysiological basis of motor and cognitive dysfunction caused by ischemic stroke. Microglia, innate immune cells of the central nervous system, mediate the neuroinflammatory response to ischemia/reperfusion. PlexinA2 (PLXNA2) plays an important role in the regulation of neuronal axon guidance, the immune response and angiogenesis. However, it is not clear whether PLXNA2 regulates microglia polarization in ischemic stroke or the underlying mechanism. In the present study, we investigated the role of PLXNA2 in rats with middle cerebral artery occlusion/reperfusion (MCAO/R) and BV2 microglia cells with oxygen and glucose deprivation/reoxygenation (OGD/R). A battery of behavioral tests, including the beam balance test, forelimb placement test, foot fault test, cylinder test, CatWalk gait analysis and Morris water maze test were performed to evaluate sensorimotor function, locomotor activity and cognitive ability. The expression of M1/M2-specific markers in the ischemic penumbra and BV2 microglia cells was detected using immunofluorescence staining, quantitative real-time PCR analysis and Western blot analysis. Our study showed that PLXNA2 knockdown accelerated the recovery of motor function and cognitive ability after MCAO/R. In addition, PLXNA2 knockdown restrained proinflammatory cytokine release and promoted anti-inflammatory cytokine release, and the mammalian target of rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3) pathway was involved in PLXNA2 regulated microglia polarization. Taken together, our results indicate that PLXNA2 knockdown reduces neuroinflammation by switching the microglia phenotype from M1 to M2 in the ischemic penumbra of MCAO/R-injured rats, which may be due to the inhibition of mTOR/STAT3 signaling. Treatments targeting PLXNA2 may be a promising therapeutic strategy for ischemic stroke.

缺血性中风是一种急性脑血管疾病，其特点是死亡率、发病率和致残率高。缺血/再灌注是缺血性卒中引起的运动和认知功能障碍的重要病理生理基础。小胶质细胞是中枢神经系统的先天免疫细胞，介导对缺血/再灌注的神经炎症反应。PlexinA2 (PLXNA2) 在神经元轴突导向、免疫反应和血管生成的调节中起重要作用。然而，目前尚不清楚 PLXNA2 是否调节缺血性卒中中的小胶质细胞极化或其潜在机制。在本研究中，我们研究了 PLXNA2 在大脑中动脉闭塞/再灌注 (MCAO/R) 和 BV2 小胶质细胞缺氧和葡萄糖剥夺/再充氧 (OGD/R) 中的作用。一系列行为测试，包括横梁平衡测试、前肢放置测试、足部故障测试、圆柱体测试、猫步步态分析和莫里斯水迷宫测试，以评估感觉运动功能、运动活动和认知能力。使用免疫荧光染色、实时定量 PCR 分析和蛋白质印迹分析检测 M1/M2 特异性标志物在缺血半暗带和 BV2 小胶质细胞中的表达。我们的研究表明，在 MCAO/R 后，PLXNA2 敲低加速了运动功能和认知能力的恢复。此外，PLXNA2敲低抑制促炎细胞因子释放并促进抗炎细胞因子释放，哺乳动物雷帕霉素靶标（mTOR）/信号转导和转录激活因子3（STAT3）通路参与PLXNA2调节小胶质细胞极化。综合起来，我们的结果表明，在 MCAO/R 损伤大鼠的缺血半暗带中，PLXNA2 敲低通过将小胶质细胞表型从 M1 转换为 M2 来减少神经炎症，这可能是由于 mTOR/STAT3 信号传导的抑制。针对 PLXNA2 的治疗可能是缺血性中风的一种有前途的治疗策略。