天然免疫抑制受体介导的非可控性肝炎恶性转化机制与免疫干预靶点研究

Innate immune “self-recognition”-mediated nonresolving inflammation including injury, fibrosis and fatty liver have been verified by us by using HBV-Tg or HBV-carrier mice in last four years, supported by this project, indicating, at least partly, that “innate immune recognition involves malignant inflammation” hypothesized by us. In this renewing project, we will use the already established HBV/HCC patient cohort, along with patient-derived xenograft (PDX) humanized mice and a variety of hepatitis-HCC mouse models, to study the role of inhibitory receptors expressed by innate immune cells such as NK cells, NKT cells and gdT cells, after comparison with the adaptive immune cell such as CD4+ T and CD8+ T cells, in promoting the transformation from liver nonresolving inflammation to malignancy (e.g. hepatitis-HCC conversion). We will focus on studying these receptors, including NKG2A, CD158b, LAG3, TIGIT and CD200R, which have been discovered by us highly liver-predominantly expresssed by innate immune cells in liver chronic inflammation in last four years, by comparison with activating receptors (including co-stimulatory factors), to explore their ligands, signaling network and blocking approaches (Abs or chemical compounds) for further confirm the roles of these innate inhibitory receptors in immune suppressing environment of liver cancer. We hope find one or two novel immune target for tumor immunotherapy through this study.

在过去4年中我们逐步证实天然免疫“自我识别”异常可导致HBV转基因或持留小鼠易发持续免疫损伤、肝脏纤维化、脂肪肝等非可控性炎症及其恶性转化，部分验证了“天然免疫识别异常可导致炎症恶性化”的假设。本项目拟以HBV肝炎肝癌病人队列为研究主体，辅以肝癌人源化小鼠队列（PDX）和多种HBV小鼠肝炎肝癌模型，研究天然免疫抑制性受体促进肝炎-肝癌的转化机制。将通过与T细胞的主要抑制性受体进行比对，确认本组前期发现的几个天然免疫细胞抑制性受体（NKG2A、CD158b、LAG3、TIGIT、CD2006等）是肝炎恶性转化的关键免疫学因素；通过与活化性受配体谱比对，动态分析炎症慢性化-恶性化过程中天然免疫抑制性受配体的关键作用；通过分析抑制性受配体的信号转导及分子网络，寻找信号通路阻断剂、靶向抗体、靶向RNA干扰等干预途径，力争寻找出1-2个针对细胞界面抑制性受配体或胞内分子的关键免疫干预靶点。

本项目通过多种HBV小鼠肝炎肝癌模型、HBV肝炎肝癌病人队列以及肝癌人源化小鼠队列（PDX）等，开展天然免疫抑制性受体促进肝炎-肝癌的转化机制研究。通过对肝脏炎症非可控性和恶性转化中天然免疫抑制性受配体为核心的受体群、配体群、细胞因子群、趋化因子群、信号通路组学、转录调控组学和表观遗传组学的系统分析，证实HCC 病人肝癌组织免疫计分可有效预测肝炎肝癌病人的生存预后，筛选验证出单独分析癌巢中CD8阳性细胞密度即可有效的预测肝炎肝癌病人的生存预后，其预测效果显著性优于目前常用的TNM分期和BCLC分期方法；发现NK细胞抑制性受体NKG2A的表达与肿瘤进程密切相关；发现慢性酒精性肝损伤中枯否细胞NLRP3炎性小体活化后进一步招募活化iNKT细胞是介导非可控性炎症的重要机制；长期饮酒诱发的肝脏炎症加快肝癌发展。证实IFN-γ/CD4+ T-CXCL9/KC-CXCR3/ CD4+ T的Cell-Cell互作网络在肝脏免疫耐受-慢性炎症平衡中起重要作用。TLR9通过促进NKT细胞和Kupffer细胞相互作用介导HBsAg转基因鼠肝脏损伤。证实天然免疫受体家族SLAMs对NK细胞驯化和自我耐受的关键作用。筛选并证实免疫抑制性受体TIGIT、PD-L1在肝炎恶性化过程中发挥重要作用，利用抗TIGIT单抗，小鼠的肿瘤免疫耐受和炎-癌转化得到逆转。发现miRNA-200c可通过表观遗传内源性负向控制PD-L1表达，而HBV特异诱发的SALL4可以阻止miRNA-200c的合成，从而实现高表达PD-L1。高表达miRNA-200c可以通过逆转HBV-相关HCC的免疫逃逸而阻止肿瘤发生发展。上述研究成果为解释肝脏炎症性疾病向肝癌转换的细胞与分子机制提供了新的线索，为临床治疗提供了可能的新的干预靶点。