Targeting iNOS Alleviates Early Brain Injury After Experimental Subarachnoid Hemorrhage via Promoting Ferroptosis of M1 Microglia and Reducing Neuroinflammation
Targeting iNOS Alleviates Early Brain Injury After Experimental Subarachnoid Hemorrhage via Promoting Ferroptosis of M1 Microglia and Reducing Neuroinflammation
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DOI：
10.1007/s12035-022-02788-5
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发表时间：
2022-03-09
影响因子：
5.1
通讯作者：
Zhang, Jian
中科院分区：
文献类型：
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作者：
Qu, Wenhao;Cheng, Ying;Zhang, Jian
许多研究已经证实了神经炎症在介导蛛网膜下腔出血（SAH）后早期脑损伤的急性病理生理事件中的作用。然而，目前尚不清楚如何在SAH后靶向这种炎症级联反应。小胶质细胞的M1激活是驱动SAH中神经炎症的重要病理机制，其被认为是侵袭性的，导致与SAH后促炎细胞因子和趋化因子释放相关的细胞毒性和强烈炎症。因此，减少M1小胶质细胞的数量是改善SAH后结局的潜在治疗目标。以往的研究发现诱导型一氧化氮合酶（inducible nitric oxide synthase，iNOS/NO center dot）通过阻断铁凋亡而在促进M1小胶质细胞存活中发挥重要作用。铁凋亡是一种新型的铁依赖性细胞程序性死亡，与哺乳动物退行性疾病、脑出血和创伤性脑损伤相关的病理性细胞死亡有关。在这里，我们研究了L-NIL，一种iNOS抑制剂，对M1小胶质细胞，神经炎症，神经元细胞死亡，脑水肿和神经功能的实验性SAH模型在体内和体外的影响。我们发现L-NIL减少了M1小胶质细胞的数量，减轻了SAH后的神经炎症。值得注意的是，用L-NIL治疗减轻了大鼠SAH后的脑水肿和神经元损伤，并改善了神经功能的结果。从机制上讲，我们发现，L-NIL抑制iNOS的表达，并通过增加铁凋亡相关蛋白的表达和脂质过氧化作用，在SAH的体外模型，这是由铁凋亡抑制剂，livestatin-1逆转促进M1小胶质细胞的铁凋亡。此外，抑制iNOS对氧合血红蛋白刺激后神经元的铁凋亡无明显影响。因此，我们的研究表明，抑制iNOS可能是一种潜在的治疗策略，通过促进M1小胶质细胞的铁凋亡和减少神经炎症来改善SAH后的结局。
Numerous studies have demonstrated the role of neuroinflammation in mediating acute pathophysiological events of early brain injury after subarachnoid hemorrhage (SAH). However, it is not clear how to target this inflammatory cascade after SAH. M1 activation of microglia is an important pathological mechanism driving neuroinflammation in SAH, which is considered aggressive, leading to cytotoxicity and robust inflammation related to the release of proinflammatory cytokines and chemokines after SAH. Thus, reducing the number of M1 microglia represents a potential target for therapies to improve outcomes after SAH. Previous studies have found that inducible nitric oxide synthase (iNOS/NO center dot) plays an essential role in promoting the survival of M1 microglia by blocking ferroptosis. Ferroptosis is a new type of iron-dependent cellular procedural death associated with pathological cell death related to mammalian degenerative diseases, cerebral hemorrhage, and traumatic brain injury. Here, we investigated the effect of L-NIL, an inhibitor of iNOS, on M1 microglia, neuroinflammation, neuronal cell death, brain edema, and neurological function in an experimental SAH model in vivo and in vitro. We found that L-NIL reduced the number of M1 microglia and alleviated neuroinflammation following SAH. Notably, treatment with L-NIL relieves brain edema and neuronal injury and improves outcomes of neurological function after SAH in rats. Mechanistically, we found that L-NIL inhibited the expression of iNOS and promoted ferroptosis of M1 microglia by increasing the expression of ferroptosis-related proteins and lipid peroxidation in an in vitro model of SAH, which was reversed by a ferroptosis inhibitor, liproxstatin-1. In addition, inhibiting iNOS had no significant effect on ferroptosis of neurons after oxyhemoglobin stimulation in vitro. Thus, our research demonstrated that inhibition of iNOS might represent a potential therapeutic strategy to improve outcomes after SAH by promoting ferroptosis of M1 microglia and reducing neuroinflammation.