基于肠道菌群调控DC-T细胞研究肺胃同治法治疗胃肠积热合并肺炎的作用机制

Gastrointestinal heat retention syndrome is the syndrome of invisible heat or tangible heat knot in the gastrointestinal and heat retention which is closely related to children's pneumonia. Yinlai Tang was effective in the treatment of pneumonia by involving both lung and stomach, but the mechanism of its action is not clear. It has been found that gastrointestinal heat retention syndrome can cause intestinal flora disturbance, which is associated with the part immune function of intestinal mucosa and the changes of immunoglobulin and inflammatory factors. Yinlai Tang can regulate intestinal flora and immune function. Studies have shown that the imbalance of intestinal flora is related to the pathogenesis of pneumonia. TLRs/NF-κB mediating DC-T cell activation plays an important role in the immune inflammatory response caused by bacteria. Based on this, we put forward the hypothesis that gastrointestinal heat causes intestinal flora imbalance, thereby activating TLRs/NF-κB signaling pathway, activating DC cells and regulating T cell differentiation, causing systemic immune dysfunction, which aggravating pneumonia. Yinlai Tang would be used in this project treating pneumonia with gastrointestinal heat retention syndrome. Via fecal bacteria transplantation and DC-T cell co culture technique in vitro, this project aims to clarify the specific mechanism of the bacteria group affecting the immune function. This study puts forward a new treatment method for children pneumonia. By discussing its scientific connotation, this study would provide experimental evidence for the treatment of this disease and improve the clinical efficacy.

胃肠积热是无形热邪或有形热结壅于胃肠而致热盛的证态，与小儿肺炎发病相关。银莱汤以肺胃同治法组方，治疗小儿胃肠积热合并肺炎疗效确切，但其作用机制尚未明确。既往发现胃肠积热可引起肠道菌群紊乱，伴随肠黏膜局部免疫功能、机体免疫球蛋白与炎症因子水平改变，而银莱汤能够调节肠道菌群及机体免疫。研究表明，肠道菌群失调与肺炎发病相关,TLRs/NF-κB介导的DC-T细胞活化在菌群引起的免疫-炎症反应中发挥重要作用。基于此提出假说：胃肠积热引起肠道菌群失调，从而激活TLRs/NF-κB信号通路，活化DC细胞并调节T细胞分化，引起全身免疫功能失调，加重肺炎。本项目拟运用胃肠积热合并肺炎动物模型，以银莱汤进行干预，通过粪菌移植及体外的DC-T细胞共培养技术，明确菌群影响免疫功能的具体作用机制。本研究提出了小儿肺炎的新治法，并探讨其科学内涵，为该病的治疗提供了实验依据，对于提高该病的临床疗效具有现实意义。

胃肠积热是高热量饮食导致的，以阳明胃肠蕴热为主的郁热证。胃肠积热常见于儿童，是临床上儿童肺炎加重的主要原因，其机制可能与高热量饮食扰乱肠道菌群，调控肠道与肺组织中DC（Dendritic Cells）细胞诱导的T细胞分化有关。本项目以中医“肺胃（肠）同治”理论为指导，探讨了中药复方银莱汤治疗胃肠积热合并小儿肺炎的作用机制。. 项目利用高热量饮食饲喂大鼠，并采用LPS雾化吸入方式，成功建立了胃肠积热合并肺炎模型，该模型表现为饮食量显著下降，趾温升高，肺组织病理炎性评分升高；机体内的炎性相关指标发生显著改变：肺泡灌洗液NE%比例、MONO%比例上升；血清促炎因子IL-1β、IL-6和TNF-α、肺组织中IL-1β和TNF-α升高；肠系膜淋巴结中Th1/Th2比例向Th1方向偏移；以及结肠与肺组织中TLR4-NFκB信号通路中MD2、NF-κB表达量升高等。而银莱汤可以通过增高调节肠道菌群（增高肠道菌群多样性），修复肠黏膜屏障（结肠组织病理）、降低炎症水平（血清、肺组织、肠组织中促炎因子水平降低）等方式来达到减轻肺部炎症的作用。在伪无菌大鼠移植了胃肠积热大鼠的粪便后出现血清促炎因子TNF-α、IL-6升高、肠组织TLR4/NF-κB信号通路的上游关键因子MD2被激活等现象，证实肺组织、血清中炎症的减轻与肠道菌群相关。项目通过细胞实验，进一步明确了胃肠积热组幼鼠肠道菌群代谢物可以影响DC2.4细胞TLR4/NF-κB 信号通路中关键蛋白表达，进一步改变成熟DC2.4细胞与T细胞共培养体系中IL-2、IL-4、IL-6、TGF-β含量，从而调控DC2.4诱导的T细胞亚群的比例变化，扰动了机体的T细胞免疫平衡，而银莱汤可以有效降低细胞中相关炎症因子的表达。. 本项目结合了动物实验和细胞实验，结果标明中药复方银莱汤通过调控肠道菌群及肠道T细胞免疫，影响了远端肺部炎症的进展，从而发挥治疗胃肠积热合并肺炎的作用。本项目研究结果为中药复方的现代化研究提供了新思路，对中药新药创制和中药作用机制的研究具有一定的指导价值。