Xie Di, Liu Huan, Xu Fei, Su Wei, Ye Qing, Yu Fang, Austin Taylor J, Chen Jun, Hu Xiaoming
Department of Neurology, School of Medicine, University of Pittsburgh, PA (D.X., H.L., F.X., W.S., Q.Y., F.Y., T.J.A., J.C., X.H.).
Geriatric Research, Education and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA (F.X., Q.Y., J.C., X.H.).
Stroke. 2021 Jun;52(6):2150-2161. doi: 10.1161/STROKEAHA.120.032444. Epub 2021 Apr 27.
Emerging evidence highlights the importance of IL33 (interleukin 33) and its receptor (ST2 [interleukin 1 receptor-like 1]) in normal brains and neurological disorders. This study explores the function of the IL33/ST2 signaling axis and a transcription factor STAT6 (signal transducer and activator of transcription 6) in white matter integrity and long-term recovery after stroke.
Transient middle cerebral artery occlusion was induced in wild type, ST2 knockout, STAT6 knockout, and microglia/macrophage-depleted (by PLX5622 diet) mice. Sensorimotor and cognitive functions were evaluated. White matter integrity was measured by immunofluorescent staining, diffusion tensor imaging, electron microscopy, and electrophysiology. The death of oligodendrocytes and its precursor cells (OPC) and the microglia/macrophage responses were evaluated 3 days after stroke. Primary microglia-oligodendrocyte/OPC cocultures were used for mechanistic studies. Parametric tests (Student t test or ANOVA) or nonparametric Mann-Whitney U test were used for statistical analysis based on the numbers of groups, types of variables, and the structure of each data set.
ST2 deficiency exacerbates sensorimotor and cognitive deficits for 28 days after middle cerebral artery occlusion compared with wild-type mice, which was accompanied by deteriorated structural damages and impaired conduction of compound action potentials in white matter. ST2 knockout mice displayed increased death of oligodendrocytes and OPCs, and a concomitant exacerbation in neuroinflammation 3 days after stroke. Using microglia/macrophage-depleted mice and microglia-oligodendrocyte/OPC cocultures, we showed that IL33 protected oligodendrocytes and OPCs against ischemic injury in a microglia/macrophage dependent manner. Further mechanistic studies identified STAT6 as a molecule that mediates the protective effects of IL33/ST2 on oligodendrocytes in the ischemic brain. IL33 treatment failed to rescue oligodendrocytes and OPCs after stroke in STAT6 knockout mice.
These results shed light on the IL33/ST2/STAT6 signaling as a potential immune regulatory mechanism to modulate microglia/macrophage activity, improve white matter integrity, and restore long-term neurological functions after stroke.
新出现的证据凸显了白细胞介素33（IL33）及其受体（ST2 [白细胞介素1受体样1]）在正常大脑和神经疾病中的重要性。本研究探讨IL33/ST2信号轴及转录因子信号转导和转录激活因子6（STAT6）在脑缺血后白质完整性和长期恢复中的作用。
对野生型、ST2基因敲除型、STAT6基因敲除型以及小胶质细胞/巨噬细胞缺失（通过PLX5622饮食）的小鼠进行短暂性大脑中动脉闭塞手术。评估感觉运动和认知功能。通过免疫荧光染色、扩散张量成像、电子显微镜和电生理学测量白质完整性。在脑缺血后3天评估少突胶质细胞及其前体细胞（OPC）的死亡情况以及小胶质细胞/巨噬细胞反应。使用原代小胶质细胞-少突胶质细胞/OPC共培养进行机制研究。根据组数、变量类型和每个数据集的结构，使用参数检验（Student t检验或方差分析）或非参数曼-惠特尼U检验进行统计分析。
与野生型小鼠相比，ST2基因缺失使大脑中动脉闭塞后28天的感觉运动和认知缺陷加剧，同时伴有白质结构损伤恶化和复合动作电位传导受损。ST2基因敲除小鼠在脑缺血后3天显示少突胶质细胞和OPC死亡增加，同时神经炎症加剧。使用小胶质细胞/巨噬细胞缺失的小鼠和小胶质细胞-少突胶质细胞/OPC共培养，我们发现IL33以小胶质细胞/巨噬细胞依赖的方式保护少突胶质细胞和OPC免受缺血损伤。进一步的机制研究确定STAT6是介导IL33/ST2对缺血性脑内少突胶质细胞保护作用的分子。在STAT6基因敲除小鼠中，脑缺血后IL33治疗未能挽救少突胶质细胞和OPC。
这些结果揭示了IL33/ST2/STAT6信号作为一种潜在的免疫调节机制，可调节小胶质细胞/巨噬细胞活性，改善白质完整性，并恢复脑缺血后的长期神经功能。
