Background: Subtypes of microglia/macrophage regulate the inflammation in the opposite direction during ischemic stroke. JAK2/STAT3 signaling pathway participates in the development of stroke-related inflammation via ischemic stimulation. However, the relationship between JAK2/STAT3 pathway and microglia/macrophage phenotype transformation is unclear. Methods: This study established a transient middle cerebral artery occlusion (tMCAO) model in male STAT3^f/f and STAT3^f/f LysM^cre+ mice and evaluated the neurological deficit on the 3rd day using Longa score. The brains were stained by TTC to determine the infarction volume. Western blotting and QPCR were used to determine the expression of JAK2/STAT3 pathway and microglia/macrophage-related markers. Immunofluorescence staining was used to detect the levels of polarization-related indexes. QPCR also assessed the effect of STAT3 knockout on inflammatory factors in the infarction. Moreover, established the OGD/R model using BV2 cells to further verify the role of STAT3 on microglia/macrophage polarization. Results: For the conditioned STAT3-KO mice, the infarction was significantly increased after MCAO, accompanied by the aggravation of neurological deficit. Higher expression of iNOS and CD16/32 than Arg-1, Ym-1, and CD206 in vivo and in vitro, and decreased p-STAT3/STAT3 ratio in STAT3^f/f LysM^cre+ mice, while the p-JAK2/JAK2 ratio increased. In addition, increased M1/M2 ratio and elevated expression of IL-1β, IL-6, TNF-α with STAT3 deletion, as well as increased CD68⁺/iNOS⁺ cell numbers. Conclusion: Collectively, these results reveal that JAK2/STAT3 signaling pathway regulates the microglia/macrophage polarization (skewing toward the M2 polarization) during the CIRI, thus alleviating brain damage. Therefore, approaches targeting JAK2/STAT3 activation are promising therapies for ischemic stroke.

背景：小胶质细胞/巨噬细胞亚型在缺血性卒中期间以相反方向调节炎症。JAK2/STAT3 信号通路通过缺血刺激参与中风相关炎症的发展。然而，JAK2/STAT3通路与小胶质细胞/巨噬细胞表型转化之间的关系尚不清楚。方法：本研究在男性 STAT3 ^f/f和 STAT3 ^f/f LysM ^cre+中建立了短暂的大脑中动脉闭塞 (tMCAO) 模型。小鼠并在第 3 天使用 Longa 评分评估神经功能缺损。用TTC对大脑进行染色以确定梗塞体积。Western印迹和QPCR用于确定JAK2/STAT3通路和小胶质细胞/巨噬细胞相关标志物的表达。免疫荧光染色用于检测偏振相关指标的水平。QPCR 还评估了 STAT3 敲除对梗塞炎症因子的影响。此外，利用BV2细胞建立OGD/R模型，进一步验证STAT3对小胶质细胞/巨噬细胞极化的作用。结果：条件性STAT3-KO小鼠MCAO后梗死面积明显增加，并伴有神经功能缺损加重。iNOS 和 CD16/32 的表达高于 Arg-1、Ym-1 和 CD206在体内和体外，STAT3 ^f/f LysM ^cre+小鼠中 p-STAT3/STAT3 比值降低，而 p-JAK2/JAK2 比值增加。此外，M1/M2 比率增加，IL-1β、IL-6、TNF-α 表达升高，同时 STAT3 缺失，以及 CD68 ⁺ /iNOS ⁺细胞数量增加。结论：总的来说，这些结果表明 JAK2/STAT3 信号通路在 CIRI 期间调节小胶质细胞/巨噬细胞极化（偏向 M2 极化），从而减轻脑损伤。因此，靶向 JAK2/STAT3 激活的方法是缺血性中风的有希望的疗法。