白介素-35介导烧伤后T淋巴细胞免疫功能障碍及其信号机制

T lymphocyte dysfunction induced by immunosuppressive cells and anti-inflammatory cytokines has been proved to be an important factor in the poor prognosis of patients with sepsis. Interleukin-35 (IL-35) is a newly discovered cytokine that is specifically secreted by regulatory T cells and has strong immunosuppressive activity for immune response. However, the potential effect and its regulatory mechanism underlying IL-35 on postburn immunosuppressive state and subsequent sepsis remains to be elucidated. In the present project, by in vitro stimulation, we firstly investigate the impact of IL-35 on immune activity of T lymphocytes (including proliferation, apoptosis, and differentiation) and the related signaling transduction pathway such as mTORC2, SGK1, and Akt. Secondly, the relationship between IL-35 expression and T lymphocyte immune activation as well as mTORC2 pathway will be further studied in severe thermal mice with delayed resuscitation. Thirdly, a prospective clinical trial will be conducted to demonstrate the pathophysiological significance of IL-35 in mediating immune dysfunction of T cells after major burns. Findings of the research will be helpful for us to deeply understand the effect of IL-35 on host immune response of T lymphocytes, and provide new clues for clarifying the pathogenesis of sepsis. Thus, the results of studies on the precise mechanisms involved in mTORC2 and downstream signaling proteins including SGK1 and Akt in IL-35 mediated immune disorder might provide an opportunity to accurately evaluate the patient’s pathophysiological status, and to develop interventional strategies for septic complications following extensive burns.

T淋巴细胞免疫障碍是引发急性损伤脓毒症及患者预后不良的重要因素。白介素(IL)-35系最新发现由调节性T细胞特异性分泌、具有强烈免疫抑制活性的细胞因子，但其异常表达与烧伤后机体免疫反应低下、并发脓毒症的关系和信号机制尚不清楚。本课题首先利用体外刺激，从多个层次和不同侧面探讨IL-35对T淋巴细胞免疫活性(包括增殖、凋亡、分化)的影响以及mTORC2、SGK1、Akt等信号通路的调节效应；其次，采用小鼠严重烫伤延迟复苏模型进一步论证mTORC2信号途径在IL-35介导T淋巴细胞免疫反应障碍中的重要作用及其调控机制；最后，通过前瞻性临床试验分析IL-35在烧伤后免疫功能紊乱、诱发脓毒症病理过程中价值。该研究有助于揭示mTORC2及其下游信号通路在IL-35介导烧伤后T淋巴细胞免疫反应中的病理生理意义，深化对烧伤脓毒症病理进程的认识，为进一步预防和调控烧伤后机体炎症反应与免疫应答过程提供新思路。

脓毒症是机体对感染的应答失控所致危及生命的器官功能障碍。免疫抑制细胞和抗炎细胞因子诱导的T淋巴细胞功能障碍已被证明是脓毒症患者预后不良的重要因素。白细胞介素(IL)-35系最新发现由调节性T细胞特异性分泌、具有强烈免疫抑制活性的细胞因子。本项目首先通过体外刺激实验发现，IL-35能够以时间/剂量依赖特性对T淋巴细胞免疫活性，包括增殖、凋亡，产生影响；mTORC2-SGK1-p27可能是IL-35调控T淋巴细胞增殖抑制效应的重要信号通路；对Rictor蛋白磷酸化位点的调节能够干扰IL-35介导的T淋巴细胞增殖抑制效应。进而通过小鼠烫伤延迟复苏模型，我们发现脓毒症下小鼠外周血及脾脏IL-35蛋白表达明显增加，其过度表达可能是造成脓毒症小鼠脾脏CD4+T淋巴细胞免疫功能障碍的关键因素，而mTORC2分子在脓毒症时IL-35介导T淋巴细胞功能障碍中扮演关键角色，通过干预IL-35和mTORC2能够有效改善脓毒症小鼠CD4+T淋巴细胞的免疫活性。该项目揭示IL-35可能系通过抑制T淋巴细胞免疫活性而造成脓毒症病程进展的关键因素，mTORC2及其下游信号通路是IL-35介导烧伤后T淋巴细胞免疫反应中的关键。项目对深化烧伤脓毒症病理进程的认识，为进一步预防和调控烧伤后机体炎症反应与免疫应答过程提供新思路。