IL-2通过抑制调节性T细胞凋亡减轻热射病的机制研究

Heatstroke morbidity is growing higher and mortality is more than 60%. Overwhelming systemic inflammatory response is one of the important pathogenesis. Regulatory T cells (Tregs) was proved to play an important role in inflammatory related diseases. Interleukin-2 could attenuate inflammatory related diseases via inhibiting Tregs apoptosis.However, whether Tregs is involved in heatstroke and IL-2 could protect against heatstorke and its potential mechanism were unknown. Our group has found decrease of serum IL-2 and splenic Tregs and increase of Treg apoptosis. In this research，we firstly established heatsroke mouse model and define illness severity as hepatic and renal function，pathology,mortality and inflammatory response; secondly, we verified whether Tregs were invovled in heatstroke via detection of illness severity in the situation of adoptive transfer or conventional depletion of Tregs; thirdly, we clarified the the attenuation of IL-2 in heatstroke and its potential mechanism by the way of multiple color flow cytometry, single photon fluorescence imaging,and etc.; at last, we optimized theraputic protocal of IL-2. With all the problems solved,our research could for the first time reveal that Tregs was involved in heatstroke and IL-2 could attenuate heatstroke via inhibiting Fas-mediated Treg apoptosis,which might provide new clue to research on mechanisms of heatstroke and IL-2 therapy in heatstroke and highlight its application in clinical practice.

热射病发病率逐年升高，死亡率60%以上。过度激活炎症反应是其重要的发病机制，调节性T细胞（Tregs）在炎症性疾病中发挥了重要作用，白介素2（IL-2）可通过抑制Tregs凋亡治疗炎症性疾病。但Tregs参与热射病及IL-2在治疗热射病中的作用及机制无人研究。前期工作发现IL-2下降、脾脏Tregs凋亡增加、数量减少。本项目建立热射病小鼠模型，将肝肾功、病理、死亡率及炎症反应作为评价疾病严重程度的参数。分别研究过继性转移Tregs或条件性敲除Tregs对疾病严重程度的影响，明确Tregs在热射病中的作用。采用多色荧光标记的流式细胞技术、免疫荧光技术等阐明IL-2通过何种机制减轻热射病，并优化IL-2的治疗方案。从而提出并验证IL-2通过抑制Fas介导的Tregs凋亡减轻热射病的科学假说。本项目的完成不仅使热射病发病机制研究获得新的突破，而且为临床应用IL-2治疗热射病奠定了坚实的理论基础。

热射病（HS）是以高热和中枢神经系统损伤为主要特征、并迅速进展为多器官功能障碍综合征的热致疾病。目前治疗上主要依靠降温和对症支持，缺乏针对发病机制的治疗方法，死亡率仍高达60%以上。全身炎症反应综合征（SIRS）是HS的核心机制，调节性T细胞(Tregs) 作为重要的免疫调节细胞，是多种炎症相关性疾病的治疗靶点。白介素2(IL-2)可通过抑制Tregs凋亡治疗自身免疫性疾病。但Tregs是否参与HS、IL-2是否可以通过减少Tregs凋亡治疗HS及其机制至今无人研究。本课题组首先建立经典型HS小鼠模型，将器官功能损伤（肝、肾和肠道）、血清细胞因子及器官炎症细胞浸润作为评价疾病严重程度的参数。分别研究过继性转移Tregs或抗体清除Tregs对疾病严重程度的影响，明确Tregs在热射病中的作用。最后，阐明IL-2/IL-2抗体复合体（IL-2C）是否可以通过抑制Tregs凋亡治疗HS。本项目重要结果如下：（1）成功建立了稳定的经典型HS模型，为后续研究提供了重要的平台；（2）HS可诱导小鼠脾脏Th细胞向Th1分化；Tregs数量、功能下降，凋亡增加；（3）Tregs是HS诱导MODS治疗的重要靶点；（4）经腹腔注射IL-2C可以改善小鼠生存率、减轻肝肾损伤；（5）IL-2C可以激活pSTAT5通路，抑制Fas介导的Tregs凋亡。. 本研究的创新性在于，首次提出并证实了Tregs在HS诱导的MODS中的重要作用，并将其作为靶点，探索IL-2C治疗HS的有效性及其机制。本研究为HS的治疗提供了新的策略，可能极大地降低HS患者的死亡率。