Toll样受体调控的NLRP3炎症小体信号通路在脆弱拟杆菌防治NEC中的作用机制

坏死性小肠结肠炎（NEC）是早产儿常见的严重疾病，死亡率高，益生菌可有效预防并缓解NEC，但作用机制未明。前期，我们分离到一株无毒脆弱拟杆菌（ZY312），预实验显示有较好的防治NEC效果，并抑制NLRP3的表达。本项目重点探讨Toll受体调控的NLRP3炎症小体信号通路在ZY312及其荚膜多糖PSA防治NEC中的作用机制。利用TLR9-/-、NLRP3-/- 和TLR2-/-小鼠建立阪崎克罗诺杆菌致NEC动物模型，体内、体外实验分析ZY312/PSA通过与TLRs的结合，是否下调NF-κB转录活性，抑制NLRP3的活化和细胞焦亡，减少促炎因子IL-1β的释放，诱导肠道Treg细胞的分化和IL-10的产生，减轻NEC对肠黏膜的损伤。明确缺失TLR9/2或NLRP3是否影响ZY312防治NEC的疗效。本研究在探讨脆弱拟杆菌防治NEC作用机制方面有理论创新，为ZY312的推广应用提供理论依据。

Necrotizing enterocolitis (NEC) is a common serious disease in premature infants. Probiotics can prevent or lessen the severity of NEC, but the protective mechanisms are not largely unknown. We sepearate a non toxic Bacteroides fragilis (ZY312) in the previous study, and showed that there was a good effect on the prevention of NEC. The aim of this project is to investigate the molecular mechanism of ZY312 and its capsular polysaccharide (PSA) in inhibiting the activation and apoptosis of NLRP3 inflammasome by binding to Toll like receptors on intestinal epithelial cells. The establishment of Cronobacter sakazakii induced NEC animal model by using TLR9-/-, NLRP3-/- and TLR2-/- mice. In vitro and in vivo experiments, we analyzed whether ZY312 and PSA combined with TLR9 and TLR2 could down regulate the transcriptional activity of NF- κ B, inhibit the activation of NLRP3 i inflammasome, reduce the release of proinflammatory cytokines IL-1 β, induce Treg to produce IL-10, and lessen the damage of NEC on intestinal mucosa. Whether the absence of TLR9, TLR2 or NLRP3 attenuated the efficacy of ZY312 and PSA in the prevention and treatment of NEC. In this study, there are theoretical innovations in the study of the mechanism of the prevention of NEC, which will provide a theoretical basis for the clinical application of ZY312.