从肠道菌群-NLRP3炎性复合体功能轴探讨清肠汤防治肠道aGVHD的机制

Intestinal aGVHD is the most common complication of allo-HSCT, whose classical theory is “cytokine storm”, but the mechanism of its initial stage is not clear. Nowadays, more and more evidences show that the intestinal flora may induce intestinal aGVHD through the innate immune responses. NLRP3 as a new hot point may lead intestinal aGVHD through the intestinal flora-inflammasome functional axis, which is the first objective of this project. In addition, nowaday's medical treatments can't prevent intestinal aGVHD effectively, which forces us to find other methods. Qingchang soup is the variation of Bai Touwen soup, whose animal experiments have confirmed its obvious effect on ulcerative colitis in rats through intestinal flora and cytokines, so the other objective of this project is to study the prevention of intestinal aGVHD by Qingchang soup. On the basis of above considerations, this article aims to confirm the mechanism of the intestinal flora-NLRP3 inflammasome functional axis in intestinal aGVHD by mice through the whole, cell and molecular levels. Besides, the aGVHD mice were pretreated by Qingchang soup to verify its preventive effect. If the hypothesis is confirmed successfully, it will open up a new perspective of intestinal aGVHD’s mechanism and provide the theoretical basis for the clinical prevention of intestinal aGVHD with traditional Chinese medicine.

肠道aGVHD是异基因造血干细胞移植最常见并发症，经典理论为“细胞因子风暴学说”，但其起病机制尚未阐明，越来越多证据显示肠道菌群可能通过机体固有免疫应答反应导致该病发生，NLRP3作为一个新切入点，其可能通过肠道菌群-炎性复合体功能轴导致肠道aGVHD发生，这是本课题旨在探索目标之一。此外，现有治疗策略难以有效防治该病，清肠汤是古方“白头翁汤”化裁而来，动物实验已证实其对大鼠溃疡性结肠炎有显著疗效，可通过改变肠道菌群及抑制细胞因子治疗肠道炎症性疾病，故本课题另一研究目标为探索清肠汤对肠道aGVHD的防治作用。在此基础上，本课题拟通过小鼠aGVHD模型，从整体、细胞及分子层面探索受者肠道菌群-NLRP3炎性复合体功能轴在肠道aGVHD中的作用机制，并以清肠汤建立相应防治模型，验证其是否通过该功能轴发挥作用，从而为肠道aGVHD发生机理开辟新视角，并为中医药临床防治该类疾病提供理论依据。

aGVHD是异基因造血干细胞移植最常见并发症，经典理论为“细胞因子风暴学说”，但其起始阶段的机制尚不明确，越来越多证据显示肠道菌群可能通过机体固有免疫应答反应影响该病发生发展，NLRs作为一个新切入点，其可能通过肠道菌群-炎性复合体功能轴导致aGVHD，本课题通过建立aGVHD受鼠模型，发现与正常对照受鼠比较，aGVHD受鼠其外周血中炎症相关细胞因子如IL-1β、IL-18、IL-10、TNF-α和MCP-1等表达水平、NLRP3炎性复合体活性以及内脏器官病理改变均有显著增高，且随着aGVHD临床症状加重，以上改变亦随之相应增高，存在统计学差异；16S rRNA检测肠道菌群发现，与正常对照受鼠比较，aGVHD受鼠肠道菌群多样性明显减少，乳酸菌等益生菌数量显著减少，但肠道菌群改变与aGVHD临床症状严重程度无正相关性，提示aGVHD可出现肠道菌群改变，但与临床症状严重程度不存在正相关。此外，现有策略难以有效控制该病，清肠汤是古方“白头翁汤”化裁而来，动物实验已证实其对大鼠结肠炎有显著疗效，可通过改变肠道菌群及抑制炎性复合体治疗炎症性疾病，故本课题另一研究目标为探索清肠汤对aGVHD的防治作用，结果发现清肠汤可下调aGVHD受鼠血清炎症相关细胞因子的表达以及NLRP3炎性复合体活性，改善其肺、脾脏、小肠等内脏器官的病理变化，并能部分恢复aGVHD受鼠肠道菌群结构及其多样性，提示清肠汤对于aGVHD有显著改善作用，其机制可能是通过恢复肠道菌群多样性以及下调NLRP3炎性复合体活性来实现的。