Tang Jun, Yue Jianhe, Tao Yihao, Zhao Guanjian, Yi Xiaoyao, Zhang Maoxin, Huang Ning, Cheng Yuan
Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, 74 Linjiang Rd, Yuzhong, Chongqing, 400010, China.
Transl Stroke Res. 2024 Dec 28. doi: 10.1007/s12975-024-01318-w.
Perihematomal edema (PHE) significantly aggravates secondary brain injury in patients with intracerebral hemorrhage (ICH), yet its detailed mechanisms remain elusive. Neutrophil extracellular traps (NETs) are known to exacerbate neurological deficits and worsen outcomes after stroke. This study explores the potential role of NETs in the pathogenesis of brain edema following ICH. The rat ICH model was created, immunofluorescence and Western blot were used to examine neutrophil accumulation, NET markers citrullinated histone H3 (CitH3) and myeloperoxidase (MPO), tight junction proteins (ZO-1 and Occludin), Aquaporin-4 (AQP4), matrix metalloproteinase-9 (MMP-9), and ERK phosphorylation (p-ERK) in brain tissues surrounding the hematoma. TUNEL staining and behavioral tests were employed to evaluate neuronal apoptosis and neurological dysfunction, while blood-brain barrier (BBB) permeability and brain edema were also measured by Evans blue and brain water content. Furthermore, the molecular mechanisms related to NETs-induced PHE were investigated using NETs, ERK, MMP-9 and AQP4 regulators, respectively. Ly6G neutrophils surrounding the hematoma developed NETs within 3 days post-ICH. NETs decreased tight junction proteins, destroyed BBB integrity, promoted brain edema, increased neuronal apoptosis, and exacerbated neurological deficits. Conversely, inhibition of NETs mitigated PHE, reduced neuronal apoptosis, and improved neurological functions. Mechanistically, NET-induced PHE was originated from impairment of BBB tight junction via ERK/MMP9 pathway, coupled with ERK-mediated AQP4 downregulation in perihematomal regions. These findings elucidated the effects of NETs on PHE, which offered promising insights for targeting NETs to relieve brain edema and secondary brain injury post-ICH.
血肿周围水肿（PHE）显著加重脑出血（ICH）患者的继发性脑损伤，但其详细机制仍不清楚。已知中性粒细胞胞外陷阱（NETs）会加重中风后的神经功能缺损并恶化预后。本研究探讨NETs在ICH后脑水肿发病机制中的潜在作用。建立大鼠ICH模型，采用免疫荧光和蛋白质印迹法检测血肿周围脑组织中中性粒细胞的积聚、NET标志物瓜氨酸化组蛋白H3（CitH3）和髓过氧化物酶（MPO）、紧密连接蛋白（ZO-1和闭合蛋白）、水通道蛋白4（AQP4）、基质金属蛋白酶-9（MMP-9）以及细胞外信号调节激酶磷酸化（p-ERK）情况。采用TUNEL染色和行为测试评估神经元凋亡和神经功能障碍，同时通过伊文思蓝和脑含水量测定血脑屏障（BBB）通透性和脑水肿情况。此外，分别使用NETs、ERK、MMP-9和AQP4调节剂研究与NETs诱导的PHE相关的分子机制。ICH后3天内，血肿周围的Ly6G中性粒细胞形成NETs。NETs降低紧密连接蛋白水平，破坏BBB完整性，促进脑水肿，增加神经元凋亡，并加重神经功能缺损。相反，抑制NETs可减轻PHE，减少神经元凋亡，并改善神经功能。机制上，NET诱导的PHE源于ERK/MMP9途径导致的BBB紧密连接受损，以及ERK介导的血肿周围区域AQP4下调。这些发现阐明了NETs对PHE的影响，为靶向NETs缓解ICH后脑水肿和继发性脑损伤提供了有前景的见解。
