ILC2细胞新亚群对肠癌发生发展的调控作用及功能机制研究

This project is based on the newly discovered ILC2 cell subpopulations to explore their regional immune characteristics and their regulatory role in the occurrence and development of colorectal cancer, which is in line with the key funding direction of "original research based on the independent discovery of new immune cell subsets of important tissues and organs". ILC cells play an important role in intestinal mucosal immunity, but the relationship between ILC cells and carcinogenesis of colorectal cancer is not clear. According to the single cell transcriptome sequencing analysis in the early stage and late stage of colorectal cancer, three groups of ILC2 cells, including ILC2-A、ILC2-B、and ILC2-C were found. ILC2-A exists in early stage tumor and inhibits tumor growth. ILC2-C exists in advanced tumors and promotes tumor growth. It was found that ILC2-C in advanced tumors was transdifferentiated from ILC2-A of early tumors. On this basis, we will further explore the biological characteristics, regional immune characteristics, regulatory role and functional mechanism of ILC2-A and ILC2-C transdifferentiation, as well as the remodeling of tumor microenvironment, and reveal the relationship between ILC2-A and ILC2-C and the tumor microenvironment remodeling.

本项目以自主发现的ILC2细胞新亚群，探究其区域免疫特性及对肠癌发生发展的调控作用，契合重点资助方向“自主发现的重要组织器官新免疫细胞亚群为基础的原创性研究”。ILC细胞在肠道黏膜免疫中发挥着重要作用，但ILC细胞与肠癌发生的关系尚不清楚。申请人前期分离肠癌早期和晚期肿瘤浸润ILC细胞进行单细胞转录组测序分析，发现肠癌肿瘤内含有三群新的ILC2细胞，包括ILC2-A、ILC2-B、ILC2-C亚群。ILC2-A存在于早期肿瘤，抑制肿瘤生长。而ILC2-C存在于晚期肿瘤，促进肿瘤生长。发现晚期肿瘤的ILC2-C是由早期肿瘤的ILC2-A转分化而来。在此基础上，我们将深入探究ILC2新亚群的生物学特征、区域免疫特性以及对肠癌发生发展的调控作用及功能机制，以及探明ILC2-A与ILC2-C转分化的分子机制及对肿瘤微环境的重塑作用，揭示ILC2细胞亚群与肠癌发生发展的关系。

申请人发现ILC2-A和ILC2-C细胞在肠道炎-癌转化中发挥重要作用，ILC2-A细胞抑制PDC肿瘤生长，而ILC2-C细胞促进PDC肿瘤生长和转化。验证了ILC2-A细胞亚群在早期结直肠癌标本中大量聚集，而ILC2-C细胞亚群在晚期结直肠癌标本中大量聚集。通过表达谱芯片筛选了在ILC3细胞中炎症诱导高表达的circRNA，利用基因敲除确定了数个重要调控ILC3细胞的人鼠同源的circRNA。其中，circZbtb20敲除小鼠ILC3细胞数目减少，circZbtb20通过稳定Nr4a1 mRNA进而激活Notch2信号，促进ILC3细胞增殖，从而维持ILC3细胞的稳态。还发现，circTmem241敲除导致ILC3的发育受损，导致肠道抗细菌感染能力减弱。ILCP中circTmem241与Nono蛋白结合并招募组蛋白甲基转移酶Ash1l启动Elk3的转录表达，从而促进其前体ILCP特异性向ILC3细胞分化。我们还发现Tuft细胞的新亚群Tuft-2细胞，Tuft-2细胞通过犁鼻器受体Vmn2r26识别细菌的代谢产物N-C11-G，活化GPCR-PLCγ2-Ca2+信号轴，进而促进前列腺素PGD2的分泌。PGD2能刺激肠道杯状细胞分泌黏液，形成黏膜层增强肠道黏膜的抗菌作用。还揭示了肠道5-羟色胺神经元调控肠道稳态和肠癌发生的机制。.通过该项目的实施完成，在ILC细胞功能机制和肠道免疫领域已发表高水平的研究论文10篇，包括Immunity（1篇）、Neuron（1篇）、Cell Research （1篇）、Nature Communications（2篇）、Cell Rep. (1篇)等国际权威期刊，超额完成了研究目标和任务。