TNF-α介导的ERS途径在大鼠弥漫性轴索损伤中的作用

Diffuse axonal injury (DAI) is one kind of severe traumatic brain injury (TBI), for which, there is still no specific and efficient therapeutics in clinical practice. In our preliminary study, we found that the expresion of tumor necrosis factor alpha (TNF-α) elevated significangly and correlated with the severity of DAI, which indicate that it may be involved in the secondary injury in DAI. Taking both the secondary injury mechanism of DAI and the dowmstream effects of TNF-α into consideration, we propose the hypothesis that the expression and accumulation of TNF-α in the injury loci of DAI may play an important role in DAI through endocytoplasmic reticulum stress (ERS) pathway to activate calpain and caspase mediated proteolysis and breakdowm axonal skeletal protein, such as neurofilament and spctrin and lead to further axonal injury and disconnection. In this study, we are to detect the exspression of TNF-α in rat brains with DAI, and then investigate its concrete mechanisms in the secondary injury of DAI in cellular and molecular level through ERS pathway. Thereafter, we plan to interfere its synthesis and downstream effects, and then observe the change of the prognosis of DAI rats. Through this programe, we are hope to get a deep understanding of the scondary injury mechanism and find the fundament of new therapeutics for DAI.

弥漫性轴索损伤（DAI）迄今为止临床上无针对性的有效治疗，预后极差。我们在前期研究中发现，在DAI大鼠脑损伤位点，炎症因子TNF-α表达量显著增高，一直持续到慢性期，并与损伤的严重程度有一定的相关性,据此我们推测其很可能参与了DAI的继发性损伤。结合DAI的继发性损伤原理和TNF-α的下游作用机制，我们假设"在DAI中，TNF-α在轴索损伤位点的合成和聚集可能会通过ERS途径激活下游的calpain介导的蛋白水解及caspase级联反应等，降解轴索骨架蛋白，导致到轴索的继发性损伤、断裂"。为证实该假设，本项目拟观察TNF-α在DAI中表达与轴索损伤位点的时间空间关系，进而在细胞和分子层面研究其通过ERS途径参与轴索继发性断裂的具体机制；并通过阻断其表达和下游作用，进一步观察干预后的DAI发展进程。通过本项目的研究，将更深入的了解DAI的继发性损伤机制，并为发展DAI治疗新方提供依据。

弥漫性轴索损伤（DAI）迄今为止的发病机制尚不明确，临床上无针对性的有效治疗，预后也极差。阐明DAI的损伤机制并以此发展针对性的治疗方案对提高DAI患者的临床疗效和改善患者的预后具有重要意义。本项目观察TNF-α 在DAI 中表达与轴索损伤位点的时间空间关系，探讨内质网应激反应在大鼠DAI继发性损伤中的作用，进而在细胞和分子层面研究其通过ERS 途径参与轴索继发性断裂的具体机制；并通过阻断其表达和下游作用，进一步观察干预后大鼠DAI的发展进程及其中可能的作用机制。项目研究发现DAI后损伤位点脑组织的TNF-α表达显著上调，且与DAI的病理过程相一致，提出TNF-α 可能参与到了DAI 的继发性损伤中，并最终导致了轴索的断裂；首次证明内质网应激反应水平在大鼠DAI后显著上调，提出ERS途径介导的细胞凋亡可能参与了DAI的病理过程；进一步通过体外实验发现TNF-α可以诱导神经元轴索断裂 和骨架蛋白的降解，促进细胞凋亡，而ERS途径的激活可能发挥关键作用；最后通过体内试验证实TNF-α抑制治疗可以减轻DAI大鼠的神经损伤，改善其神经功能，其中ERS途径可能参与了TNF-α抑制治疗的神经保护机制。该项目提出了DAI继发性损伤新的病理机制，为DAI的治疗提供新的思路和理论依据。