Tim-3信号通路调控巨噬细胞极化在幽门螺杆菌感染免疫致病和免疫防治中的作用

Macrophages are important innate immune cells whose functions of antigen presentation and immunological effect play a major role in the pathogenic infection and immune protection of vaccine. They can differentiate to two distinct functional phenotypes (M1 and M2 macrophages).Our previous studies have indicated that both H.pylori infection and H.pylori vaccination can enhance Th1 immune response and active TLR signaling pathways. However, we found that the Th1 immune and TLR signaling pathways responded to different results in the immune pathogenesis of H.pylori infection and immune protection of vaccine against H.pylori, and its regulating mechanism is still obscure. Tim-3 signaling pathway correlate closely with Th responses and TLR signaling pathways, by which Tim-3 can regulate macrophage polarization. Thus, we hypothesize that Tim-3 signaling pathway could regulate macrophage polarization by different routes in the immune responses of H.pylori infection and H.pylori vaccination. As a result, the different macrophage phenotypes affect its function of antigen presentation and immunological effect, leading to different outcomes of H.pylori infection and H.pylori vaccination. Therefore, in this study, we focus on following problems:①the impact of H.pylori infection and H.pylori vaccination on macrophage polarization;②the role of Tim-3 in regulating macrophage polarization and its effect on the pathogenesis of H.pylori infection and immune protection of vaccine against H.pylori using Tim3 transgenic animal models;③the possible molecular mechanism by which Tim-3 regulate macrophage polarization in H.pylori infection. In summary, we aim to explore the possible mechanism of the pathogenesis of H.pylori infection and immune protection of vaccine against H.pylori from the perspective of macrophage polarization, thus providing a new target for prevention of H.pylori-related diseases.

巨噬细胞(Mφ)的抗原递呈和免疫效应功能在病原体致病和疫苗免疫保护中起重要作用，它有两种功能不同的极化状态（M1和M2）。我们前期研究发现幽门螺杆菌（Hp）感染和疫苗接种均可增强Th1反应和激活TLRs信号通路，但它们在Hp感染和疫苗接种时分别产生免疫致病和免疫保护不同的结果，其机制不明。Tim-3信号通路与Th反应和TLRs信号通路密切相关，且可通过TLRs信号通路等途径调控Mφ极化。我们设想在Hp感染和疫苗接种时Tim-3信号通路通过不同途径调控Mφ向不同方向极化，从而影响其功能，导致了Hp感染和疫苗接种的不同结局。为此本项目拟研究：①Hp感染和疫苗接种对Mφ极化的影响；②在转基因动物模型中研究Tim-3对Mφ极化的调控及其在Hp致病和疫苗免疫保护中的作用；③Tim-3调控Hp感染时Mφ极化的分子机制。以期从Mφ极化的角度探讨Hp致病和疫苗免疫保护机制，为Hp相关性疾病防治提供新靶点。

幽门螺杆菌（Hp）感染是慢性胃炎、消化性溃疡和胃癌的主要病因，WHO已将其列为胃癌的I类致癌因子。Hp感染引起的持续性不可控炎症，导致胃黏膜炎症损伤，最终发生“炎-癌”转化。然而，Hp感染的致病机制目前仍未完全阐明。为此，本项目进行了以下研究：①Hp感染和Tim3对巨噬细胞极化的影响和机制，及其在Hp致病中的作用；②Hp感染调控PGK1表达的机制及其在Hp致病中的作用；③Hp感染调控ACE2表达及对胃上皮细胞的生物学过程影响。结果表明：①Hp感染可调控巨噬细胞极化，且巨噬细胞极化在Hp感染中是一个动态变化过程；②Hp感染增强巨噬细胞的吞噬功能，而Tim3可进一步增强巨噬细胞的吞噬功能；③Hp感染可显著上调Tim-3的表达，后者参与了巨噬细胞极化的调控；④转录组学分析发现巨噬细胞靶向敲除Tim-3影响小鼠胃黏膜水解酶活性及对含氧化合物的反应，并与cAMP、cGMP-PGK信号通路密切相关，而Hp感染与DNA重组、细胞凋亡及PPAR信号通路等密切相关；⑤在肿瘤微环境中，tim3主要调控巨噬细胞向M2极化，Hp刺激后能进一步增强其调控作用。胃癌组织中tim-3表达高于癌旁组织，主要是由于免疫细胞中tim-3表达引起的；免疫相关的信号通路在tim-3高表达的表型中富集, tim-3的表达与巨噬细胞浸润水平呈正相关，且巨噬细胞浸润程度与胃癌患者预后密切相关；⑥Hp感染可上调PGK1的表达且与疾病的发生密切相关，Hp可通过上调PGK1的表达，促进胃上皮细胞的增殖、侵袭及迁移；⑦Hp感染诱导胃上皮细胞PGK1线粒体移位，促进糖酵解；Hp感染通过ROS、p53和MITF调控PGK1的表达，进而影响细胞糖酵解；⑧Hp感染可上调ACE2的表达，并且与其介导的胃黏膜病变过程密切相关，ACE2可促进胃上皮细胞的增殖、迁移和侵袭。以上结果为Hp相关性疾病的防治提供了新靶点。