幽门螺杆菌调控胃上皮源性NR1D1介导胃黏膜免疫抑制微环境形成及感染慢性化的作用及机制研究

Helicobacter pylori (H. pylori) infection is an important factor of chronic gastritis and gastric cancer. H. pylori infection-induced gastric mucosal immunosuppressive microenvironment is one of the key causes to the failure of bacterial eradication by host immune response; however, the underlying mechanism of this is unknown. Previously, we found that H. pylori infection could regulate nuclear receptor subfamily 1 group D member 1 (NR1D1), a nuclear transcription factor with properties of immunosuppression, expression and increase by gastric epithelial cells, suggesting that this gastric epithelial-derived NR1D1 might be involved in the formation of gastric mucosal immunosuppressive microenvironment and the following chronic H. pylori infection. Thus, we aim at this NR1D1, and intend to investigate (1) the clinical significance and role of gastric epithelial-derived NR1D1 in the formation of gastric mucosal immunosuppressive microenvironment and chronic H. pylori infection; (2) the regulating mechanism of H. pylori infection in the activation of MAPK/ERK-AP-1 pathway to induce the expression of NR1D1 in gastric epithelial cells; (3) the effector mechanism of gastric epithelial-derived NR1D1 in the formation of gastric mucosal immunosuppressive microenvironment and chronic H. pylori infection; by using NR1D1 knockout (NR1D1-/-) mice, , and also in terms of cytology, immunology and molecular biology technology. This study may provide new experimental evidence for the pathological mechanism and clinic treatment of chronic H. pylori infection.

幽门螺杆菌（Hp）感染是慢性胃炎乃至胃癌发生的重要因素，感染所诱导的胃黏膜免疫抑制性微环境是宿主免疫清除细菌“失能”继而导致感染慢性化的重要因素之一；但其机制尚不清楚。前期发现，Hp感染可显著诱导胃上皮细胞表达免疫抑制功能的核转录因子NR1D1，提示胃上皮源性NR1D1参与了Hp感染介导免疫抑制微环境形成并促进了Hp感染慢性化。因此，本项目拟以此NR1D1为研究对象，利用NR1D1基因敲除小鼠，运用细胞学、免疫学及分子生物学等技术，（1）明确胃上皮源性NR1D1在Hp感染中介导免疫抑制微环境形成及Hp感染慢性化的临床意义及作用；（2）揭示Hp感染激活MAPK/ERK-AP-1通路，诱导胃上皮细胞表达NR1D1的调控机制；（3）阐明Hp感染中，胃上皮源性NR1D1介导胃黏膜免疫抑制微环境形成及Hp感染慢性化的效应机制。相关研究将为Hp感染慢性化病理机制的阐明和临床治疗提供新的实验证据。

研究背景与：核受体NR1D1是一种参与代谢、免疫和昼夜节律的转录抑制因子。然而，NR1D1在幽门螺杆菌感染中的调控机制、功能效应及其临床相关性目前尚不清楚。. 研究内容：在幽门螺杆菌感染患者和小鼠的胃样本中检测NR1D1表达情况。分离胃上皮细胞并进行幽门螺杆菌感染胃上皮细胞调控NR1D1表达实验。幽门螺杆菌感染NR1D1敲除小鼠（NR1D1-/-）及同窝对照野生型小鼠、上述小鼠交互骨髓嵌合体小鼠、过继IFN-γ敲除小鼠（IFN-γ-/-）和野生型小鼠CD4+T细胞的野生型小鼠及NR1D1-/-小鼠、体内注射NR1D1激活剂或抑制剂的野生型小鼠，分离上述小鼠的胃组织进行细菌定殖检查。分离、刺激和/或培养胃上皮细胞、CD45+CD11c-Ly6G-CD11b+CD68-髓系细胞和CD4+T细胞进行NR1D1功能实验。. 重要结果：幽门螺杆菌感染患者和小鼠胃粘膜中NR1D1表达增高。幽门螺杆菌依赖毒力因子cagA通过激活ERK-NF-κB通路诱导胃上皮细胞表达NR1D1，后者导致胃粘膜内细菌定植增加。其效应机制为，NR1D1不仅直接抑制Reg3b和β-defensin-1的表达，导致这些抗菌蛋白在体外和体内对幽门螺杆菌的杀菌作用减弱；而且还直接抑制趋化因子CCL21的表达，这导致CD45+CD11c-Ly6G-CD11b+CD68-髓系细胞的胃组织内浸润减少，进而降低了机体特异性Th1细胞应答对幽门螺杆菌清除能力。. 科学意义：幽门螺杆菌感染能诱导一种新的调节因子NR1D1，该调节因子通过抑制宿主胃上皮细胞抗菌相关基因表达，而这些抗菌相关基因表达是抵抗幽门螺杆菌的局部先天性和适应性防御所必需的，相关效应促进了胃组织细菌定植，介导了幽门螺杆菌感染慢性化，