巨噬细胞M2极化促进ILC2活化在H.pylori感染致Th1/Th2免疫失衡中的作用及机制研究

The occurrence of Helicobacter pylori (Hp) infection-related gastric diseases is closely associated with the imbalance of Th1/Th2 immune, and group 2 innate lymphoid cell (ILC2) is known to play a critical role in Th2 immunity. We have found for the first time that ILC2 was increased and activatied after Hp infection, moreover, we have also demonstrated that macrophages were necessary for the Hp infection-induced ILC2 activation. Furthermore, a positive correlation between the proportion of ILC2 and M2 macrophage after Hp infection has been found. Therefore, we speculated that M2 macrophages were involved in the activation of ILC2 during Hp infection. Moreover, gene expression profiling revealed that IDO and TSLP were up-regulated in macrophages after Hp stimulation, while miR-27a-3p was down-regulated. Previous studies have shown that IDO could lead to M2 polarization, and our preliminary experiments suggested that miR-27a-3p might target TSLP, which was a classical factor that activated ILC2. Therefore, this project intends to confirm our scientific hypothesis “Hp infection ➔ IDO in macrophage↑➔ macrophage M2 polarization ➔ miR-27a-3p↓➔ TSLP↑➔ ILC2 activation” by applying microbiological, immunological and molecular biological technique, and provides a target and theoretical basis for the prevention and treatment of gastric diseases caused by Hp infection.

幽门螺杆菌（H.pylori，Hp）感染相关性胃疾病的发生与Th1/Th2免疫失衡密切相关，2型固有淋巴细胞（ILC2）在Th2免疫中发挥重要作用。我们前期首次发现Hp感染可促进ILC2增殖和活化，且这一过程需要巨噬细胞的参与；并发现ILC2比例与M2巨噬细胞比例呈显著正相关。因此，我们推测M2巨噬细胞参与Hp感染促进的ILC2活化。表达谱分析示Hp刺激后巨噬细胞中IDO、TSLP上调，miR-27a-3p下调。研究表明IDO可促进M2极化；预实验提示miR-27a-3p可靶向调控TSLP，而后者是活化ILC2的经典因子。因此，本项目拟采用微生物学、免疫学、分子生物学等技术进行研究，以证实“Hp感染➔巨噬细胞IDO↑➔M2极化➔miR-27a-3p↓➔TSLP↑➔ILC2活化”这一机制在Hp感染引起的Th1/Th2免疫失衡中的作用，为防治Hp感染相关性胃疾病提供靶点和理论基础。

背景：幽门螺杆菌（Helicobacter pylori，H.pylori）一旦感染无法自行清除，长期的慢性感染通过改变局部胃黏膜微环境及全身各系统的免疫应答，引起H.pylori感染相关性疾病，严重者导致胃癌的发生，是公认的胃癌I类致癌因子。2型固有淋巴细胞（ILC2）及巨噬细胞在黏膜屏障免疫中发挥重要作用。本项目的前期研究发现H.pylori感染可导致Th1/Th2失衡及ILC2细胞比例增加，而M2巨噬细胞作为抗原提呈细胞，可促进ILC2的激活与持续活化，但两者之间的关系不明。因此本项拟探明H.pylori感染对巨噬细胞M2极化、ILC2活化和Th1/Th2免疫失衡的影响，及相关的分子机制。.方法： 本项目主要通过以下方面进行探索求证，1）耗竭/去除巨噬细胞、构建不同巨噬细胞模型、过继转移巨噬细胞等，研究巨噬细胞及其M2极化在H.pylori感染中对ILC2活化及Th2免疫的影响；2）清除小鼠体内ILC2后，构建H.pylori感染模型，研究ILC2对M0细胞极化为M2的影响；3）研究巨噬细胞分泌的TSLP对ILC2细胞活化、促进Th2免疫的影响；4）构建si-IDO，转染M0细胞，研究IDO表达对M0极化为M2的影响。 .结果：（1）巨噬细胞M2极化参与H.pylori感染所致的ILC2活化；（2）ILC2的活化并不影响巨噬细胞M2极化；（3）M2巨噬细胞分泌的TSLP参与促进ILC2活化；（4）IDO参与调控H.pylori感染中巨噬细胞的M2极化。.结论：本项目初步探明了H.pylori感染通过改变巨噬细胞的极化状态从而引起ILC2的异常活化的过程及可能的机制，为提供干预靶点、指导临床治疗提供理论依据。