炎症小体对肠道炎症调节功能的研究

Inflammatory bowel disease (IBD) is becoming common in China and emerging as a new issue of digestive disease research. Currently there are a few single-nucleotide polymorphisms of NLRP3 inflammasome-associated genes have been found in IBD patients, suggesting that NLRP3 may play an important role in IBD, but its exact role and mechanism remains to be clarified. To solve this problem, the applicant will utilize NLRP3 inflammasome inhibitors as well as conditional knockout mice to identify its exact function in different stages and intestinal cells during IBD; Since some reports have suggested NLRP3 of intestinal epithelium protect against IBD, we will also generate NLRP3 or ASC deficient mice expressing fluorescent protein in intestinal epithelium to analyze the downstream effectors of NLRP3 of intestinal epithelium by flow sorting and RNA sequencing techniques and investigate their function in IBD, thereby revealing the possible mechanisms of epithelial NLRP3 in regulating IBD; Additionally recent studies show that high-fiber diet(HFD) can inhibit IBD development. Our preliminary study found that high-fiber diet could promote intestinal epithelial inflammasome activation. Therefore, the applicant will feed NLRP3 or ASC deficient mice with HFD and its metabolites and colonize HFD-fermenting gut bacteria on these mice, combining studies about the downstream effectors of NLRP3, to explore the regulatory function of molecular link between NLRP3 inflammasome, diet and gut flora in IBD. Taken together, our studies will clarify important molecular events of IBD, providing theoretical basis for the prevention of IBD and establishment of effective clinical means in IBD intervention.

肠道炎症在我国越来越普遍，正成为消化疾病研究新热点。目前肠炎患者体内已发现NLRP3类炎症小体基因单核苷酸多样性突变，提示其在肠炎形成过程中有重要作用，但确切角色和作用机制仍有待澄清。因此，申请人将首先用NLRP3炎症小体抑制剂和条件敲除小鼠，阐明肠炎发生不同阶段以及不同肠道细胞中NLRP3炎症小体可能的不同角色；针对NLRP3炎症小体在肠道上皮细胞可能发挥肠道保护的作用，申请人将用流式分选和RNA测序技术去寻找其在肠道上皮效应分子并研究它们功能，进而揭示NLRP3炎症小体在肠道上皮调节肠道炎症的分子机制；此外，已知高纤维饮食可保护肠道抑制肠炎发生，我们初步研究发现高纤维饮食可促进肠上皮炎症小体激活，因此我们还将用高纤维饲料和其代谢分子喂养NLRP3类炎症小体基因敲除小鼠，并定植可代谢高纤维饮食肠道菌，同时结合肠上皮效应分子的研究，来探究NLRP3炎症小体与饮食、肠道菌群之间的分子关联对肠炎发生的调节功能。通过这些研究，申请人将有望阐明肠炎形成过程中重要分子事件，并为肠道炎症的预防，以及建立有效临床干预手段奠定理论基础。

炎症性肠病（IBD）是一种发病机制复杂的慢性消化道炎症疾病，其病理特征为肠道炎症失控，进而导致肠道组织炎症病理损伤。现有的治疗方法虽能一定程度上控制炎症，但不能有效根治该病，并且极易发生复发。鉴于IBD难于治疗这一临床紧迫问题，深入剖析IBD的发病机制变得尤为重要。炎症小体是多蛋白复合体炎症机器，在肠道黏膜免疫和炎症性肠病发生过程中炎症小体有着重要作用，但其功能复杂，具体调控机制仍有待阐明。. 在本项目中，申请人围绕相关科学问题，着重探究了炎症小体下游新近鉴别的焦亡关键效应分子Gasdermin D (GSDMD)在结肠炎发生以及肠道免疫中的调节作用。我们观察到GSDMD蛋白在化学诱导的结肠炎小鼠肠道被显著激活。敲除小鼠研究发现GSDMD缺乏可加重小鼠实验性结肠炎发生，并且该表型与肠道菌群无关，此外，GSDMD缺失也不影响抗菌肽（AMPs）产生和粘膜蛋白分泌。通过条件性敲除小鼠研究我们还发现是巨噬细胞而非肠上皮细胞中GSDMD缺乏导致严重的实验性结肠炎表型。并且我们进一步证明，GSDMD在巨噬细胞中是通过负调节cGAS依赖性炎症，进而控制结肠炎发生。当我们给药cGAS抑制剂后可以有效缓解GSDMD缺陷小鼠的结肠炎表型。. 综上，我们的研究发现首次证明了GSDMD在控制结肠炎中的作用，并详细描述了其潜在的调控机制。同时，我们的研究也为开发特异性靶向GSDMD-cGAS信号的炎症性肠病防治策略提供了线索。