米诺环素通过Notch信号通路调控小胶质细胞极化在脊髓缺血后延迟性瘫痪中作用的研究

During surgical repair of thoracic and thoracoabdominal aortic aneurysms, the aorta has to be occluded, and this causes spinal cord ischemia which consequently results in spinal cord injury and even delayed paraplegia in some patients after surgery. Though many methods have been used to reduce the incidence of delayed paraplegia after aortic surgery, but the effectiveness of these methods remains uncertain. Our previous study showed that minocycline attenuated the neurologic deficit and reduced the incidence of delayed paraplegia. However, the exact mechanism of minocycline neuroprotection is not clear. Recent studies demonstrated minocycline could modulate microglia polarization. The aim of this study is to clarify the hypothesis of minocycline neuroprotection in a rat model of spinal cord ischemia through modulating microglia polarization via the Notch signaling pathway. We demonstrate a spinal cord ischemia rat model, and confirm the critical role of microglia polarization and delayed spinal cord injury. In vitro, to investigate the change of microglia polarization induced by LPS or IL-4. To observe the change of rat spinal cord injury after spinal intrathecal injection of primary microglia pre-induced by LPS or IL-4. In vitro, to study the influence of Notch signal system on polarization of microglia, and investigate the regulation of minocycline on microglia polarization state through Notch signaling pathway. In conclusion, the results of this study will provide the solid evidence to prove our hypothesis.

行主动脉瘤修复术时需要对主动脉进行阻断，造成脊髓缺血，延迟性瘫痪是术后最严重的并发症，目前尚无公认有效的防治方法。我们之前的研究发现米诺环素可以降低大鼠脊髓缺血后延迟性瘫痪的发生率，但机制未完全明确。有研究显示，米诺环素可使小胶质细胞由促炎M1型转化为抗炎M2型。据此我们推测，米诺环素可能通过调控小胶质细胞的极化，减少了炎症因子的释放，减轻了缺血后脊髓损伤。首先我们将通过建立大鼠脊髓缺血模型，观察脊髓缺血后小胶质细胞的极化情况及炎症因子的变化；其次，分别将M1型为主、M2型为主的小胶质细胞鞘内注射入大鼠体内；明确小胶质细胞极化与脊髓损伤之间的关系。再次，在离体实验中，明确Notch信号通路在小胶质细胞极化中的作用。最后，以米诺环素对LPS、IL-4诱导的小胶质细胞进行干预，探讨其是否通过Notch信号通路对小胶质细胞的极化进行了干预。本课题将进一步明确米诺环素减轻缺血后脊髓损伤的作用机制。

行主动脉瘤修复术时需要对主动脉进行阻断，造成脊髓缺血，延迟性瘫痪是术后最严重的并发症，介导延迟性瘫痪产生的神经生物学机制尚未阐明。课题组构建大鼠脊髓缺血模型，应用分子生物学手段解析脊髓缺血后脊髓小胶质细胞的极化及分子机制，取得了以下科研成果：1）脊髓缺血可诱导大鼠延迟性瘫痪，促进小胶质细胞向M1型极化，诱导炎症反应和神经元损伤；2）小胶质细胞的M1型极化可加剧大鼠脊髓缺血引起的延迟性瘫痪和炎症反应，小胶质细胞的M2型极化可防止脊髓缺血引起的损伤，对脊髓缺血大鼠具有保护作用；3）米诺环素可通过Notch信号通路调控小胶质细胞极化，从而降低炎症反应并保护脊髓运动神经元；4）亚低温及自噬均可通过影响小胶质细胞极化，从而降低炎症反应并保护脊髓运动神经元，进而减轻脊髓缺血后的神经损伤。本课题首次阐明脊髓缺血后小胶质细胞的极化失衡，及其在缺血后延迟性脊髓损伤中的作用；米诺环素通过Notch信号通路对小胶质细胞极化产生影响，进而减轻了缺血后的神经损伤，降低了延迟性瘫痪的发生率，为临床干预脊髓缺血提供了新的思路和科学依据。课题组严格按项目计划开展实验，在全部完成项目研究内容的基础上，额外拓展亚低温及自噬影响小胶质细胞极化的神经生物学机制研究，取得了良好的科研成果。截止2022年12月，在该项目的资助下共发表SCI科技论文4篇。课题执行4年来，培养硕士研究生3名。同时，该项目的顺利执行为课题组进一步拓展脊髓缺血后延迟性瘫痪的发生与治疗机制奠定了坚实的基础。