氙气延迟后处理对兔脊髓缺血再灌注损伤的保护作用及SAFE细胞信号机制研究

Spinal ischemic injury is the serious sequela of aortic surgery with the occurence high up to 10%-36%, and the patients with it suffered poor living quality and even death. Our ongoing work granted by National Natural Science Foundation of China showed that xenon postconditioning decreased apopotosis index and provided spinal protection from ischemia/reperfusion injury in rats.The effects of xenon postconditioning beginning at 1h after reperfusion were better than that of beginning immediately or 2h after reperfusion, which indicate that there may be optimal therapeutic window in the xenon postconditioning. This study will, first, establish spinal ischemia/reperfusion injury model in rabbit and explore the therapeutic window of spinal protection of xenon delayed postconditioning, comparing the effects of spinal protection of different xenon inspiration time. Then, we will investigate the role of SAFE pathway and RISK pathway in spinal protection of xenon delayed postconditioning after spinal ischemia/reperfusion injury in rabbit, and explore the mechanism of SAFE pathway by using JAK/STAT3 antagonist or not. We'll also study the connection of SAFE pathway and RISK pathway in it by using ERK antagonist or PI3K antagonist respectively, so as to determine the spinal protection, therapeutic window and mechanism of xenon delayed postconditioning in spinal ischemia/reperfusion injury model in rabbit and provide experimental data support for patients suffering spinal ischemic injury after aortic surgery using xenon postconditioning clinically.

大血管手术后脊髓缺血性损伤发生率高达10%-36%，严重危害患者的生活质量与生命安全。我们在研国自然课题表明氙气后处理可以减轻大鼠脊髓缺血再灌注后的凋亡程度，再灌注后1h氙气后处理效果明显好于再灌注即刻组与2h组，提示可能存在氙气后处理脊髓保护最佳时间点。本研究拟通过建立兔脊髓缺血再灌注模型，系统研究氙气延迟后处理脊髓保护作用的治疗时间窗以及不同吸入时程的氙气后处理的脊髓保护效果；通过观察SAFE与RISK信号通路在氙气后处理脊髓保护中的动态变化，并使用JAK/STAT3阻滞剂阻断SAFE通路，研究SAFE通路在氙气后处理作用中的机制，结合使用ERK与PI3K阻滞剂阻断RISK通路，研究氙气后处理脊髓保护作用中SAFE通路与RISK通路的交互联系，旨在进一步揭示氙气后处理在脊髓缺血再灌注损伤脊髓保护的治疗时间窗及其机制，为临床大血管术后脊髓损伤患者使用氙气后处理提供实验依据。

本研究通过建立兔脊髓缺血再灌注模型，进行组织学、凋亡染色、蛋白印迹法检测及免疫组织化学染色等方法，发现了：1）胶质细胞和SAFE通路中p-STAT3在兔脊髓缺血再灌注损伤后呈现不同的活化规律，小胶质细胞于再灌注后8h达到高峰，星形胶质细胞再灌注后48h达到高峰，p-STAT3呈现双高峰，分别在再灌注1h和48h，观察上述指标变化情况将为临床干预的时机和手段提供理论依据。2）首次发现兔脊髓缺血再灌注损伤后7小时内吸入50%的氙气均有保护作用，其中以再灌注后2h吸入的保护效果最佳。3）本研究于国内外首次发现再灌注后即刻给予氙气后处理不仅没有脊髓保护作用甚至可能有损害作用，再灌注72h观察与炎症反应有关的小胶质细胞特异性标记物、IL-6表达情况示再灌注即刻通氙气组均明显高于缺血再灌注组。4）氙气对兔脊髓缺血再灌注损伤的保护作用与通气时长有关，再灌注1h内吸入2h 50%的氙气比吸入1h 50%的氙气保护作用强。5）于氙气保护作用最强的时间点给予JAK/STAT3选择性阻滞剂JSI-124，发现氙气后处理可以抑制JAK/STAT3通路的过度激活从而发挥保护作用。实验内容已全部完成，并加做了胶质细胞动态变化观察实验。相关数据正在收集和整理。上述结果证实了氙气延迟后处理对兔脊髓缺血再灌注损伤存在保护时间窗，再灌注7h内给予氙气治疗均有保护作用，作用最强时间点为再灌注2h和3h，而即刻给予氙气后处理没有保护效果甚至有损伤作用；氙气对脊髓损伤的保护作用与吸入时长相关，SAFE细胞信号通路可能是氙气脊髓保护的机制之一。