GATA-3调控固有淋巴细胞ILC2在幽门螺杆菌感染致病中的作用及机制研究

Type 2 innate lymphoid cells (ILC2) are recently discovered as one of the crucial mediators in chronic inflammation and immune response, and the differentiation and cytokine secretion of ILC2 are both dependent on GATA-3 expression. Our previous study discovered the enrichment of transcriptional factor GATA-3 in lymphocyte of H.pylori infected gastric mucosa of gastric cancer patients, and ILC2 has been successfully isolated from these lymphoid cells in H.pylori positive gastric mucosa. This study is to introduce various types of H.pylori to infect ILC2 to investigate the effect on GATA-3 expression. The ILC2 morphology, biological properties and related inflammatory cytokine expression regulated by GATA-3 are detected in GATA-3 overexpressing and silencing condition. Potential targets for GATA-3 are further detected by chromatin imunoprecipitation sequencing (ChIP-seq), bioinformatics techniques and dual luciferase reporter assay in these cell models. Furthermore, the samples of H.pylori infected animal models and patients are used to validate the molecular mechanisms. These studies will elucidate the GATA-3 related molecular mechanisms in ILC2 and prognosis of H.pylori associated diseases, and be used for providing novel preventive targets against H.pylori chronic infection.

新近研究发现固有淋巴细胞ILC2的增殖分化和细胞因子分泌依赖于GATA-3的调节，其在慢性炎症和免疫反应中扮演重要角色。前期研究发现幽门螺杆菌（H.pylori）感染胃癌患者胃黏膜中有GATA-3表达阳性的淋巴细胞，并分离鉴定出ILC2。本项目拟构建ILC2细胞模型，考察不同H.pylori菌型（CagA基因东方型、西方型等）感染致其GATA-3表达改变，及转染致其GATA-3基因过表达与沉默后ILC2细胞形态、生物学特性和细胞因子的变化，以明确GATA-3与ILC2的增殖分化和细胞因子之间的关系；通过ChIP-seq和双荧光素酶实验确定GATA-3的靶基因；并采用H.pylori感染动物模型及H.pylori感染相关性疾病患者样本进行实验验证，由此阐明GATA-3对ILC2的调控机制及其在H.pylori感染致病和转归中的作用，为临床防治H.pylori感染提供新靶点。

幽门螺杆菌（Helicobacter pylori，H.pylori）感染可诱导局部胃黏膜微环境及全身各系统的免疫应答改变，从而引起H.pylori感染相关性疾病。在H.pylori感染相关性疾病中常表现为Th2免疫（抑制性免疫）反应占优势，致使Th1/Th2免疫失衡，继而导致免疫抑制和免疫逃逸，形成促进胃癌发生发展的微环境，最终促进胃癌的发生发展。2型固有淋巴细胞（ILC2）是新近发现的Th2型细胞因子的重要来源，在黏膜屏障的固有免疫中发挥重要作用。我们前期研究发现，H.pylori感染可引起ILC2的转录因子GATA-3升高，初步证实H.pylori感染可导致Th1/Th2失衡及ILC2细胞比例增加。本研究进一步证实H.pylori感染引起Th2型细胞因子增加，Th1型细胞因子减少，致使Th1/Th2免疫失衡，其与ILC2增加有关；并进一步研究表明：H.pylori感染可促进ILC2活化，但H.pylori感染不能直接活化ILC2，且对骨髓内ILC2细胞的数目无影响，而通过促进外周组织中巨噬细胞M2极化，继而活化ILC2，导致Th1/Th2免疫失衡。其机制是H.pylori感染通过诱导巨噬细胞IDO表达，促进巨噬细胞M2极化，继而分泌TSLP，促进ILC2活化，导致Th1/Th2免疫失衡。其中GATA-3、IDO和TSLP作为这一通路中的关键分子，有望成为阻断H.pylori感染致病的新靶点。