Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Jiefang Road 88th, Hangzhou, 310000, China.
J Neuroinflammation. 2020 May 25;17(1):165. doi: 10.1186/s12974-020-01830-4.
Neuroinflammation is closely associated with the poor prognosis in subarachnoid hemorrhage (SAH) patients. This study was aimed to determine the role of stimulator of IFN genes (STING), an essential regulator to innate immunity, in the context of SAH.
A total of 344 male C57BL/6 J mice were subjected to endovascular perforation to develop a model of SAH. Selective STING antagonist C-176 and STING agonist CMA were administered at 30 min or 1 h post-modeling separately. To investigate the underlying mechanism, the AMPK inhibitor compound C was administered intracerebroventricularly at 30 min before surgery. Post-SAH assessments included SAH grade, neurological test, brain water content, western blotting, RT-PCR, and immunofluorescence. Oxygenated hemoglobin was introduced into BV2 cells to establish a SAH model in vitro.
STING was mainly distributed in microglia, and microglial STING expression was significantly increased after SAH. Administration of C-176 substantially attenuated SAH-induced brain edema and neuronal injury. More importantly, C-176 significantly alleviated both short-term and persistent neurological dysfunction after SAH. Meanwhile, STING agonist CMA remarkably exacerbated neuronal injury and deteriorated neurological impairments. Mechanically, STING activation aggravated neuroinflammation via promoting microglial activation and polarizing into M1 phenotype, evidenced by microglial morphological changes, as well as the increased level of microglial M1 markers including IL-1β, iNOS, IL-6, TNF-α, MCP-1, and NLRP3 inflammasome, while C-176 conferred a robust anti-inflammatory effect. However, all the mentioned beneficial effects of C-176 including alleviated neuroinflammation, attenuated neuronal injury and the improved neurological function were reversed by AMPK inhibitor compound C. Meanwhile, the critical role of AMPK signal in C-176 mediated anti-inflammatory effect was also confirmed in vitro.
Microglial STING yielded neuroinflammation after SAH, while pharmacologic inhibition of STING could attenuate SAH-induced inflammatory injury at least partly by activating AMPK signal. These data supported the notion that STING might be a potential therapeutic target for SAH.
神经炎症与蛛网膜下腔出血（SAH）患者的预后不良密切相关。本研究旨在确定干扰素基因刺激物（STING）作为先天免疫的重要调节剂，在 SAH 中的作用。
344 只雄性 C57BL/6J 小鼠接受血管内穿孔以建立 SAH 模型。分别在建模后 30 分钟或 1 小时给予选择性 STING 拮抗剂 C-176 和 STING 激动剂 CMA。为了研究潜在机制，在手术前 30 分钟通过侧脑室给予 AMPK 抑制剂化合物 C。SAH 后评估包括 SAH 分级、神经学测试、脑水含量、western blot、RT-PCR 和免疫荧光。将氧合血红蛋白引入 BV2 细胞，在体外建立 SAH 模型。
STING 主要分布在小胶质细胞中，SAH 后小胶质细胞 STING 表达明显增加。给予 C-176 可显著减轻 SAH 引起的脑水肿和神经元损伤。更重要的是，C-176 显著缓解了 SAH 后的短期和持续神经功能障碍。同时，STING 激动剂 CMA 显著加重了神经元损伤并恶化了神经损伤。在机制上，STING 激活通过促进小胶质细胞活化和向 M1 表型极化来加重神经炎症，这表现在小胶质细胞形态变化以及小胶质细胞 M1 标志物包括 IL-1β、iNOS、IL-6、TNF-α、MCP-1 和 NLRP3 炎性体的水平增加，而 C-176 则具有强大的抗炎作用。然而，C-176 的所有有益作用，包括减轻神经炎症、减轻神经元损伤和改善神经功能，都被 AMPK 抑制剂化合物 C 逆转。同时，在体外也证实了 AMPK 信号在 C-176 介导的抗炎作用中的关键作用。
SAH 后小胶质细胞 STING 产生神经炎症，而 STING 的药物抑制至少部分通过激活 AMPK 信号减轻 SAH 引起的炎症损伤。这些数据支持 STING 可能是 SAH 的潜在治疗靶点的观点。
