TNFα促进Tc9生成的作用和机制以及在肿瘤免疫治疗中的应用

Tc9 is a recently described IL-9-secreting Tc cell subset, showing to mediate potent antitumor effects in vivo. Therefore, understanding the mechanisms of Tc9 cell differentiation and identification of new factors to induce and expand Tc9 cells may have high clinical significance in tumor immunotherapy. Tc9 cells can be generated in vitro by culturing naïve CD8+ T Cells under the condition of TGF-β and IL-4 plus anti-CD3/CD28 antibodies, the same as Th9-polarizing condition, suggesting that the mechanisms underlying Tc9 and Th9 cell differentiation are similar. We recently found that TNFα potently promoted naïve CD4+ T cells to differentiate into Th9 cells and naïve CD8+ T cells to differentiate into Tc9 cells, suggesting that TNFα is a new Tc9/Th9-polarizing factor. CD4+ T cells express TNFR1 and TNFR2. We found that TNFα drove Th9 differentiation through TNFR2 but not TNFR1. CD8+ T cells also express TNFR1 and TNFR2. Thus we believe that TNFα also enhances Tc9 cell differentiation through TNFR2. We found that TNFα activated STAT5 in T cells. STAT5 is a known Th9-related transcription factor and increases IL-9 expression in T cells. Our preliminary data show that TNFα-induced Tc9 cells expressed increased granzyme B (GzmB) and IL-24. GzmB is a well-characterized cytolytic factor and IL-24 induces tumor cell apoptosis. Based on these observations, we hypothesize that TNFα promotes Tc9 cell differentiation through TNFR2/STAT5 signaling pathway; TNFα-induced Tc9 cells exert potent ant-tumor activity through the production of IL-9, GzmB and IL-24. In this project, we will investigate the role of TNFα in the induction of Tc9 cells. We will clarify the mechanisms underlying TNFα-induced Tc9 cell development. Finally, we will examine the roles and mechanisms of TNFα-induced Tc9 cells in tumor therapy. Successful completion of these studies will help us better understand the mechanisms of Tc9 cell differentiation and its antitumor effects, and may have important clinical implications.

Tc9是具有优异抗肿瘤潜能的新的Tc亚型，但其分化机制还不清楚。体外诱导Tc9的极化条件与Th9完全相同，说明Tc9与Th9的分化机制可能类似。我们最近发现TNFα体外促进Tc9和Th9生成，提示TNFα是一种新型Tc9极化因子。我们也发现TNFα活化STAT5，并通过TNFR2而非TNFR1促进Th9生成，同时CD8+T细胞也表达TNFR1/2。据此，我们推测TNFα同样通过TNFR2/STAT5促进Tc9分化。TNFα体外诱导的Tc9表达更高水平的IL-9、GzmB和IL-24等潜在的抗肿瘤效应分子。根据这些研究，本课题科研假设：TNFα通过TNFR2/STAT5信号途径促进Tc9分化，并通过促进Tc9表达IL-9、GzmB和IL-24等效应分子增强其抗肿瘤效应。本课题的目的是阐明TNFα促进Tc9生成和发挥抗肿瘤效应的作用和机制，具有重要的理论意义和临床应用价值。

恶性肿瘤是威胁人类生命与健康的主要疾病之一，迫切需要开发有别于传统治疗的新方法，T细胞过继免疫治疗因具有高特异性、无交叉耐受，并能提供长期的免疫保护等特性，成为肿瘤治疗的热点探索方向之一。效应T细胞包括CD8+细胞毒性T淋巴细胞（CTLs）和CD4+辅助性T细胞（Th）。Th9和Tc9是具有优异抗肿瘤潜能的新的Th/Tc亚型，但其分化机制还不清楚。本课题研究发现TNFα通过TNFR2而非TNFR1促进Tc9生成，并且能够通过TNFR2促进Tc9增殖并抑制其凋亡；TNFα不能促进Tc9细胞的体外杀伤活性，但是能够促进Tc9细胞体内的抗肿瘤效应。由于TGFβ能够抑制CD8+T细胞的活性及增殖能力，极大的限制了Tc9细胞抗肿瘤治疗的应用，但是TGFβ对CD4+T细胞没有明显的影响，我们后期主要研究了TNFα对Th9分化及功能的促进作用。结果表明TNFα同样通过TNFR2而非TNFR1促进Th9生成，并且能够通过TNFR2促进Th9增殖并抑制其凋亡；TNFα能够促进Th9细胞的体内抗肿瘤效应；TNFα通过STAT5和NF-κB信号通路促进Th9分化。本课题阐明了TNFα促进Tc9和Th9生成和发挥抗肿瘤效应的作用和机制，具有重要的理论意义和临床应用价值。