目的 在永久缺血性脑卒中小鼠模型上，探讨外周血中性粒细胞浸润对大脑原位小胶质细胞的极化调控。方法 取58只C57BL/6小鼠，分为假手术组和模型组，对模型组小鼠实施永久性大脑中动脉阻塞手术。术后48 h、7 d、14 d和30 d处死小鼠，灌注取材。Western blotting检测脑组织中M1型小胶质细胞标志物CD16、M2型标志物精氨酸酶1(Arg1)、炎症因子白细胞介素-1β(IL-1β)及中性粒细胞标志物髓过氧化物酶(MPO)的水平。免疫荧光法检测脑切片梗死区周围中性粒细胞浸润及M2型小胶质细胞分布。在体外实验中，将分离纯化的中性粒细胞与小胶质细胞BV2共培养，脂多糖刺激后，观察BV2吞噬中性粒细胞的情况，并检测共培养后BV2细胞CD16和Arg1蛋白的表达水平。 结果 Western blotting显示，小鼠术后脑组织中CD16（P＜0.05）、IL-1β（P＜0.001）和MPO（P＜0.05）的水平在48 h和7 d显著增高，随后下降，MPO于术后30 d恢复正常。免疫荧光显示，小鼠大脑皮层梗死区周围的MPO阳性细胞在术后48 h显著增加（P＜0.001），随后降低（P＜0.05）。小胶质细胞标志物离子钙结合适配分子1(Iba1)和MPO双阳性细胞在术后逐渐增多，14 d达到最高（P＜0.05），Iba1和Arg1双阳性细胞也在术后7 d（P＜0.05）和14 d（P＜0.01）显著上升。体外共培养显示，BV2吞噬中性粒细胞后，CD16显著下降（P＜0.05），Arg1显著上调（P＜0.05）。 结论 在永久缺血性脑卒中小鼠模型中，小胶质细胞吞噬中性粒细胞后从M1型向 M2型转变，损伤脑区由促炎转变为抗炎状态。

Objective To investigate the effects of peripheral blood neutrophil infiltration on the polarization regulation of cerebral resident microglia under a permanent ischemic stroke model.    Methods  Fifty-eight C57BL/6 mice were divided into two groups. One group was sham group, and the other group of mice was subjected to permanent middle cerebral artery occlusion surgery. Mice were euthanized 48 hours, 7 days, 14 days, and 30 days after surgery for tissue collection. Western blotting was used to detect expression levels of M1 microglia markers CD16, M2 microglia marker arginase 1(Arg1), inflammatory cytokine interleukin-1β (IL-1β), and neutrophil marker myeloperoxidase (MPO) in brain tissue. Immunofluorescence histochemical staining was used to assess neutrophil infiltration and M2 microglial distribution around the infarct area in brain sections. In vitro, purified neutrophils were co-cultured with BV2 microglial cells. After lipopolysaccharide stimulation, the phagocytosis of neutrophils by BV2 cells was observed, and the expression levels of CD16 and Arg1 proteins in BV2 cells were detected.    Results Western blotting showed that the levels of CD16 (P<0.05), IL-1β (P<0.001), and MPO (P<0.05) in brain tissue increased significantly 48 hours and 7 days after surgery, then decreased, with MPO expression returning to normal levels 30 days after surgery. Immunofluorescence showed a significant increase of MPO-positive cells around the infarct area of the mouse cerebral cortex 48 hours after surgery (P<0.001), followed by a decrease (P<0.05). The number of ionized calcium binding adapter molecule 1 (Iba1) and MPO double-positive cells gradually increased after surgery,  and reached their peak at 14 days (P<0.05). Iba1 and Arg1 double-positive cells also increased significantly 7 days (P<0.05) and 14 days (P<0.01) after surgery. In vitro, co-culture experiments showed that after BV2 phagocytosing neutrophils, CD16 (P<0.05) significantly decreased and Arg1 significantly upregulated (P<0.05).    Conclusion  In a permanent ischemic stroke model, microglia transition from M1 to M2 type after phagocytosing neutrophils, and the injured brain area changes from pro-inflammatory state to anti-inflammatory state.