IL-36促进CD8+T细胞分泌IL-9在肿瘤免疫中的作用及机制

There were researches reporting that IL-9 is a very critical antitumor cytokine. IL-9 is mainly secreted by CD4+ Th9 cells which are induced by IL-4 and TGF-β. In addition, using the same method can induce “Tc9 cells” from CD8+ T cells. Although “Tc9 cells” can secret IL-9 in vitro, they lose the ability of secreting IL-9 in vivo. In the past, we found that IL-36 can play an important role in antitumor immunity by activating CD8+ T cells. However, the mechanism is not very clear. In recent work, we found that IL-36 can promote CD8+T cells secreting IL-9 in vitro. Experiments in vivo also suggested that IL-9 maybe the effector of IL-36 antitumor immunity. On the basis of this original discovery, we put forward the scientific hypothesis that IL-36 plays a very important role in antitumor immunity through promoting CD8+T cells secreting IL-9. In this study, we are going to do the following work: ①to research the effects of IL-36 promoting CD8+T cells secreting IL-9 and the molecular mechanism; ②to research promoting CD8+T secreting IL-9 is the critical pathway of IL-36 inhibiting tumor; ③to research the relationship between IL-36 expression, CD8+T cells secreting IL-9 and the clinical significance in human colonic cancer. In all, this study is in order to lay new foundation for CD8+ T cells antitumor immunity theory and provide new valuable clue for clinical application.

研究提示IL-9是重要的抗肿瘤因子，其主要来源是经IL-4、TGF-β诱导的CD4+的Th9细胞。而同样方法诱导的CD8+“Tc9细胞”虽在体外可分泌IL-9，但在体内却失去了分泌IL-9的能力。我们前期发现IL-36可以激活CD8+T而发挥显著的抗肿瘤作用；最近又发现IL-36在体内、外均可以显著促进CD8+T分泌IL-9。在此原创性发现的基础上，提出“IL-36通过IL-9在CD8+T介导的抗肿瘤免疫中发挥重要作用”这一科学假说。本课题拟开展如下研究：①IL-36促进CD8+T分泌IL-9的作用及分子机制；②IL-36促进CD8+T分泌IL-9是其发挥抗肿瘤效应的重要途径；③人结肠癌肿瘤组织中IL-36表达、CD8+T细胞分泌IL-9的相关性及临床意义。总之，本项目旨在丰富CD8+T抗肿瘤免疫的理论基础，为临床运用提供有价值的线索。

IL-9是重要的抗肿瘤因子，IL-4、TGF-β联合刺激的CD8+T细胞可分泌IL-9，该群细胞被命名为“Tc9细胞”，该诱导途径被称为Tc细胞的经典诱导途径。本课题组前期发现IL-36可以显著促进CD8+T分泌IL-9，并且其作用优于经典诱导途径。进而，本课题验证了IL-36通过诱导CD8+T细胞分泌IL-9，即向Tc9细胞分化而介导抗肿瘤免疫的作用和机制。本课题经研究发现：1. IL-36能显著促进CD8+T分泌IL-9，并上调IL-10、IL-17a、 IL-21、IL-22等细胞因子的表达，并促进了IFN-γ、FasL、穿孔素、GzmA、GzmB、GzmC等效应性分子的表达，同时下调Foxp3的表达。2. IL-36的该促进作用依赖于STAT6､STAT5和NF-κB信号通路，并与IL-36上调转录因子BATF、BATF3表达水平密切相关。3. 与经典诱导CD8+T细胞分泌IL-9途径相比，IL-36促进分化的Tc9细胞具有更好的肿瘤过继免疫治疗效果，能够更有效地抑制肿瘤生长，延长荷瘤小鼠生存期。4. 该群细胞过继治疗后可维持较高的数量，并低表达免疫卡控点分子CD244、PD-1和KLRG-1。IL-36促进分化的Tc9保持了与经典Tc9基本一致的记忆表型，并且高表达IFN-γ和Granzyme B等Tc1细胞特征性细胞因子。总之，本项目基本阐明了IL-36通过诱导CD8+T细胞分泌IL-9，即向Tc9细胞分化而介导抗肿瘤免疫的作用和分子机制，丰富了CD8+T抗肿瘤免疫的理论基础，为将细胞因子IL-36运用于临床肿瘤免疫治疗提供了有价值的线索。