肝-肠组织驻留ILC的起源图谱及其界面交互作用

The present project matches closely with the first research field listed in the guidelines of "Regional immunity of tissues and organ" program. Our previous project has revealed that the adult liver contained ILC1 progenitors and liver ILC1s are a heterogeneous population. Considering the liver-gut axis and the enrichment of ILCs in the liver and gut，the present project will combine three independent groups based on their expertise in the study of liver and intestinal ILCs as well as in microscopic imaging and single cell sequencing. By utilizing the technologies of single cell sequencing, high-resolution and multi-parameter imaging, fate-mapping animal models and bioinformatics, the present project will describe the heterogeneous composition of liver-gut ILCs in a dimension of time and space, demonstrate the hematopoietic origin of different ILC subsets, confirm whether intestinal commensal bacteria are critical in determining the replacement of liver ILC1 subsets during ontogeny, and also explore whether bile acid metabolism is involved in gut ILC maintenance, We aim to comprehensively depict the origin picture of tissue-resident ILCs in the liver and gut and the role of liver-gut axis in maintaining the tissue-resident ILC subset，thereby providing new insight into the mechanisms underlying the tissue-specific immunologic features of liver and gut ILCs.

本项目与“组织器官区域免疫特性与疾病重大研究计划"申请指南重点资助方向中的第一项高度契合。在课题组前期所发现的肝脏存在ILC1的造血前体及肝脏ILC1异质性的基础上，结合肝-肠在解剖学和功能上的密切联系及其富含ILC的共同特征，拟集成三个项目团队在肝-肠ILC研究、成像和测序等技术上的优势，进一步利用单细胞测序、高分辨率多参数及3D成像技术、谱系示踪模型、生物信息学分析等手段，从时间和空间上动态描绘肝脏和肠道ILC的异质性组成，并以肝脏ILC1为核心，与肠道ILC亚群进行比对，阐明其不同亚群的造血起源，进一步确定肠道共生菌群是否为影响肝脏ILC1亚群更替的重要因素，明确肝脏来源的胆汁酸代谢对肠道ILC稳态的影响，力争全面描绘肝-肠组织驻留ILC亚群的起源图谱和肝-肠轴对组织驻留ILC亚群的作用，为肝-肠ILC亚群的区域免疫特性形成机理提供解释。

在围绕肝脏ILC1开展的前期研究基础上，结合肝-肠在解剖学和功能上的密切联系及其富含ILC的共同特征，本项目集成三个项目团队在ILC研究、成像和测序等技术上的优势,进一步探索肝-肠组织驻留ILC的起源图谱及其界面交互作用，取得以下进展：（1）结合单细胞测序等技术手段，解析了肝脏造血前体细胞的异质性，并为该前体向ILC1发育分化提供了新证据，明确了IFN-γ正向调控该发育路径；（2）深入探究了肝脏ILC1的异质性，揭示Ly49E可将肝脏ILC1划分为表型、功能、造血起源存在显著差异的两个亚群，其中Ly49E+ILC1主要由胚胎造血前体产生，出生后可长期自我维持而不依赖造血前体细胞，而Ly49E− 群体则在出生后依赖造血前体细胞的不断补充；借鉴肝脏ILC1研究体系，解析了肠道ILC随个体发生的异质性组成，并揭示肠道ILC亚群也存在骨髓非依赖的造血起源；（3）发现Kupffer细胞清除导致肝脏ILC1数量减少和分化成熟受阻，并证明该影响依赖于共生菌，提示Kupffer细胞以肠道共生菌依赖的方式促进肝脏ILC1分化成熟；（4）发现肠道细菌感染可导致肝脏炎症，ILC在其中发挥抑制作用，而肝脏损伤及并发胆汁酸代谢失调可加重肠道炎症。