Abstract: Objective To investigate the effect of miR-21 on neuroinflammation after subarachnoid hemorrhage (SAH) and its potential mechanism through in vitro and in vivo experiments. Methods In vitro,Transfection of N9 microglial cells with miR-21 mimics mediated by a transfection reagent was performed to upregulate miR-21 expression; a dual-luciferase reporter assay was conducted to verify that miR-21 can target and regulate the TLR4 gene; the effects of miR-21 overexpression on the TLR4/NF-κB inflammatory pathway were detected using RT-qPCR,Western Blot,and ELISA.In vivo,a rat SAH model was established by endovascular perforation,and miR-21 mimics were administered via intracerebroventricular injection.At 24 h post-modeling,neurological function was assessed using the modified Garcia score,and SAH severity was evaluated by the Sugawara score.TLR4 expression in the cerebral cortex was detected by immunohistochemistry and Western Blot. Results In vitro,Transfection with miR-21 mimics successfully upregulated miR-21 expression in N9 microglial cells; miR-21 was confirmed to target and regulate the TLR4 gene; overexpression of miR-21 inhibited the expression of TLR4,NF-κB,and related inflammatory factors.In vivo,overexpression of miR-21 significantly improved neurological function scores,reduced SAH severity,and suppressed the number of TLR4-positive cells and TLR4 protein expression in the cerebral cortex of SAH rats. Conclusion miR-21 alleviates neuroinflammation after SAH by targeting and inhibiting the TLR4/NF-κB signaling pathway and reducing the release of inflammatory factors,thereby exerting a neuroprotective effect.

Key words: miR-21, Subarachnoid hemorrhage, Neuroinflammation

摘要： 目的 通过体内外实验探讨miR-21对蛛网膜下腔出血(SAH)后神经炎症的作用及其潜在机制。方法 体外实验中,转染试剂介导miR-21 mimics转染到N9小胶质细胞上调miR-21的表达;双荧光素酶报告基因实验验证miR-21可以靶向调控TLR4基因;通过RT-qPCR、Western Blot和ELISA实验检测miR-21过表达对TLR4/NF-κB炎症通路的影响。体内实验中,采用颈内动脉穿刺法建立大鼠SAH模型,侧脑室注射miR-21 mimics;术后24 h采用改良Garcia评分评估神经功能,Sugawara评分评估出血严重程度;免疫组化和Western Blot检测脑皮质中TLR4的表达。结果 体外实验结果显示,转染试剂介导miR-21 mimics转染到N9小胶质细胞可以上调miR-21的表达;miR-21可以靶向调控TLR4基因;过表达miR-21可以抑制TLR4、NF-κB及其相关炎症因子的表达。体内实验显示,过表达miR-21可以改善SAH大鼠的神经功能评分,减轻SAH出血严重程度,可以抑制SAH脑皮质中TLR4的阳性细胞数和蛋白表达水平。结论 miR-21可通过靶向抑制TLR4/NF-κB信号通路减少炎症因子释放,减轻SAH后神经炎症,发挥神经保护作用。

关键词: miR-21, 蛛网膜下腔出血, 神经炎症