Nrf2-ARE信号通路在脂多糖诱导创伤性脊髓损伤大鼠早期耐受中的作用及机制研究

Traumatic spinal cord injury (TSCI) is a disease of high disability rate. The early treatment has a important role in progonosis. The early drug treatment of TSCI is not so effective. It is highly necessitous to investigate the complexity of signalling network of nerve cells in early injury and to identify new therapeutic targets. Recently, the effects of LPS-induced cross-tolerance in central nervous system (CNS) provide a new direction for the treatment of brain and spinal cord injury. But the mechanisms are not fully understood. We preliminary studies found that nuclear factor Nrf2 and downstream pathway were one of key mechanisms involving in LPS-induced protective tolerance for early spinal cord injury, and LPS-induced protective tolerance were significantly strengthened or attenuated in Nrf2-overexpressed or Nrf2-silenced neurons, respectively. Furthermore, ERK1/2 kinase is likely to a key bridging molecule between LPS and nuclear factor Nrf2. In the study, we built a standard TSCI model. Through evaluating neurologic function, observing the changes of nerve cells apoptosis and detecting the changes of correlation factors expression, we will explain systematically the mechanism of LPS-mediated ERK1/2/Nrf2-ARE pathway in early tolerance of spinal cord. Our research will shed light on the new role of LPS-induced cross-tolerance in CNS and provide new ideas for early intervention of high risk patients with SCI, in the same time, our work will identify new pathway for early treatment in TSCI.

创伤性脊髓损伤（TSCI）是一类高致残率的疾病，其早期治疗效果对其预后至关重要，目前的早期治疗药物效果不够理想，急需对损伤早期细胞内信号传导网络复杂性进一步了解，发现新的治疗靶点。近来，脂多糖（LPS）诱导中枢神经系统交叉耐受的效应为脑脊髓损伤治疗提供了新方向，但机制未完全阐明。我们前期研究发现，核因子Nrf2及下游通路是LPS诱导脊髓损伤早期耐受的关键机制之一，高表达或沉默Nrf2基因对其诱导的耐受产生明显的正负效应；且ERK1/2激酶可能是LPS与核因子Nrf2之间的关键桥接分子。本研究拟围绕标准化脊髓创伤模型，通过评价神经功能改善，观察脊髓凋亡变化和检测通路分子表达变化，从细胞和动物水平全面阐述ERK1/2/Nrf2-ARE通路在LPS诱导脊髓系统早期耐受中的作用机制，为LPS诱导交叉耐受的理论机制提供新线索，为SCI高危患者早期干预提供新思路，同时为脊髓创伤的早期治疗提供新途径。

创伤性脊髓损伤（TSCI）是一类高致残率的疾病，其早期治疗效果对其预后至关重要，目前的早期治疗药物效果不够理想，急需对损伤早期细胞内信号传导网络复杂性进一步了解，发现新的治疗靶点。 我们前期研究发现，核因子Nrf2及下游通路是脂多糖（LPS）诱导脊髓损伤早期耐受的关键机制之一，而高表达或沉默Nrf2基因对其诱导的耐受产生明显的正负效应；Nrf2-ARE通路激活与炎症通路中间分子PI3K和ERK1/2密切相关。因此，本课题主要围绕脊髓创伤模型阐述Nrf2-ARE通路在LPS诱导脊髓系统早期耐受中的作用机制。首先建立PC12和BV2细胞的脊髓损伤体外模型，探讨过表达或沉默ERK1/2对LPS预处理PC12和BV2细胞增殖能力及下游Nrf2和HO-1蛋白的影响，结果表明ERK1/2是低剂量LPS诱导Nrf2和HO-1表达上调的关键中间分子。进一步分析低剂量LPS介导ERK1/2及PI3K对PC12细胞Nrf2-ARE抗氧化通路的调控机制，阐述了脂多糖调控脊髓损伤细胞模型更精准的保护机制，即脂多糖预处理PC12细胞后通过激活胞内PI3K-AKT/Nrf2信号轴发挥重要的抗氧化保护效应。最后采用标准化TSCI动物模型，研究低剂量LPS预处理对大鼠脊髓创伤抗氧化的作用机制，结果表明LPS通介导ERK1/2-Nrf2/ARE 通路有效诱导脊髓组织产生交叉耐受性保护，促进局部脊髓组织抗氧化因子表达，降低脊髓组织继发性凋亡和后肢运动功能缺损。这些发现为LPS诱导交叉耐受的理论机制提供新线索，为SCI高危患者早期干预提供新思路，同时为脊髓创伤的早期治疗提供新途径。