Regulation of IL-7R expression in thymocytes and memory T cells

IL-7是T淋巴细胞发育和动态平衡所必需的细胞因子。然而，对其α链(IL-7Rα)在T细胞发育后期的作用知之甚少。为了解决这个问题，我们建立了IL-7Rα转基因小鼠，并将它们与CD4Cre转基因小鼠杂交。由此产生的小鼠(IL-7RcKO)显示CD8单一阳性(SP)T细胞、调节性T细胞(Tregs)和自然杀伤T(NKT)细胞显著减少。此外，CD4SP和CD8SP成熟胸腺细胞的比例和增殖均降低，与各亚群功能相关的基因表达减少。IL-7RcKO小鼠也表现出Treg和NKT细胞增殖受损，NKT细胞成熟受抑。IL-7RcKO小鼠胸腺中B细胞、γδT细胞和树突状细胞数量增加。总之，本研究表明IL-7Rα在发育后期的胸腺细胞亚群中具有多种功能，并提示αβT细胞上IL-7R的表达抑制了胸腺其他细胞系的发育。

IL-7 is a cytokine essential for T lymphocyte development and homeostasis. However, little is known about the roles of itsα-chain(IL-7Rα) in late stages of T cell development. To address this question, we established IL-7Rα-floxed mice and crossed them with CD4-Cre transgenic mice. Resultant mice(IL-7RcKO) mice exhibited marked reduction in CD8 single positive(SP) T cells, regulatory T cells(Tregs) and natural killer T(NKT) cells. In addition, the proportion and proliferation of both mature CD4SP and CD8SP thymocytes were decreased, and expression of genes important for function of each subset was decreased. IL-7RcKO mice also showed impaired Treg and NKT cell proliferation and inhibition of NKT cell maturation. IL-7RcKO mice exhibited increased numbers of B,γδT, and dendritic cells in thymus. Overall, this study demonstrates that IL-7Rαhas multiple functions in thymocyte subpopulations in late developmental stages and suggests that IL-7R expression onαβT cells suppresses development of other cell lineages in thymus.