白细胞介素37对脓毒症状态下调节性T细胞免疫功能障碍的影响及其调节机制

Interleukin-37 (IL-37) can down-regulate the innate immunity and adaptive immunity.The protective anti-inflammatory role has been approved in various inflammatory diseases. Also, regulatory T cells (Tregs) play critical roles in sepsis induced immune dysfunction. With both animal experiments and clinical observations, the present project was conducted to investigate the effect of IL-37 on immune function of Tregs in the pathogenesis of sepsis. Firstly, rhIL-37/IL-37 siRNA were employed to regulate IL-37 signal in Tregs. Immune response of Tregs was analyzed, including the expression of surface molecules, secretary cytokines, and suppressive activity to effector T cells. Secondly, signal of AMPK, an autophagy related molecule, was regulated by AMPK agonist/inhibitor and AMPK-siRNA. Thus, the potential role of autophagy would be clarified in IL-37 mediated regulation of Tregs. Thirdly, IL-37 expression on Tregs in peripheral blood of septic patients was determined, and the relationship between IL-37 expression and activity of Tregs was analyzed. From the current study, we will try to elucidate the possible role of IL-37 in the immune dysfunction of Tregs during sepsis. Moreover, IL-37 mediated signal transduction in Tregs might be clarified. These insightful findings on IL-37 and its downstream signal would explore a new way for immunomodulatory strategy in septic complications.

白细胞介素37(IL-37)下调固有免疫和获得性免疫，在多种炎症疾病中发挥抗炎效应。调节性T细胞(Treg)在脓毒症免疫功能障碍中发挥重要作用。本项目拟通过动物实验和临床观察，以Treg为观察对象，应用重组人IL-37 (rhIL-37)或IL-37小干扰RNA (siRNA)调控IL-37信号，探讨脓毒症状态下IL-37对Treg抑制性分子表达、细胞因子分泌及其对效应T细胞抑制活性的影响。同时应用腺苷单磷酸活化蛋白激酶(AMPK)激动剂、抑制剂和AMPK-siRNA从蛋白/基因水平调控自噬信号分子AMPK，借此澄清自噬在IL-37调控Treg免疫活性中的地位。此外，分析脓毒症患者外周血Treg中IL-37表达与Treg免疫活性之间的关系及临床意义。该课题旨在明确脓毒症状态下IL-37对Treg免疫功能紊乱的影响及其信号机制，通过对IL-37及其下游信号的调控，为脓毒症免疫治疗提供新思路。

脓毒症是失控的宿主炎症反应导致的威胁生命的器官功能障碍。ICU内脓毒症患者死亡率高，预后差。调节性T细胞控制脓毒症免疫反应，对脓毒症的预后是有利的。白细胞介素-37(IL-37)属于抗炎细胞因子，可以下调固有免疫和获得性免疫。先前研究表明，IL-37可以上调调节性T细胞的免疫功能。然而，在脓毒症状态下IL-37如何影响调节性T细胞的功能，其具体机制尚未阐明。本研究显示，IL-37上调LPS环境中调节性T细胞内 LC3II 和Atg5水平(P＜0.05),提示自噬被激活。另外，Treg细胞的CTLA-4 和Foxp3抑制性分子表达水平与Treg细胞自噬水平正相关。IL-37促进Treg细胞分泌TGF-β，自噬抑制剂3-MA可以逆转此现象 (P＜0.001)。相似的，敲减自噬相关基因Beclin1 和Atg5，可以产生与3-MA类似的效应 (P＜0.05)。IL-37上调Treg细胞自噬水平的同时，Treg细胞内p-AMPK-α蛋白水平表达升高。AMPK选择性抑制剂Compound C可以逆转IL-37对Treg免疫功能促进效应 (P＜0.001)。IL-37改善脓毒症小鼠的预后，PC61、Compound C和Beclin1敲减可以逆转IL-37的生存保护效应（P＜0.05）。 总之，IL-37经AMPK激活自噬信号，促进Treg的免疫功能。