IL-27 stimulation in Foxp3+ Tregs improves suppressive function and therapeutic efficacy

Foxp3 expressing regulatory T cells (Tregs) are the central regulator of immune homeostasis and tolerance. As it is believed that proper Treg function is compromised under inflammatory conditions, exploring a pathway that enhances Treg function is of great importance. In this study, we report that IL-27, an IL-12 family cytokine known to play both pro- and anti-inflammatory role in T cells, plays a pivotal role in Treg function to control T cell-induced colitis. Unlike WT Tregs capable of inhibiting colitogenic T cell expansion and inflammatory cytokine expression, IL-27R-deficient Tregs were unable to downregulate inflammatory T cell responses. Tregs stimulated with IL-27 expressed substantially enhanced suppressive function both in vitro and in vivo. IL-27 stimulation of Tregs induced expression of LAG3, a surface molecule implicated in negatively regulating immune responses. LAG3 expression in IL-27-stimulated Tregs was critical to mediate suppressive Treg function. Finally, human Tregs also displayed enhanced suppressive function and LAG3 expression in response to IL-27 stimulation. Taken together, our results highlight a novel function of the IL-27/LAG3 axis in Treg regulation of inflammatory responses in the intestine. FACS purified Foxp3+ Tregs were stimulated in the presence of media or IL-27 to compare IL-27 induced gene profiles. Four samples (media stimulated or IL-27-stimulated) were collected from four independent experiments. Genes altered by IL-27 treatment were compared to those of media stimulated Tregs.

表达叉头框蛋白P3（Foxp3）的调节性T细胞（Tregs）是免疫稳态与免疫耐受的核心调控因子。现有研究证实，炎症状态下Treg的正常功能会受到损伤，因此探寻能够增强Treg功能的通路具有重要科学意义。本研究证实，白介素27（IL-27）——一种在T细胞中兼具促炎与抗炎活性的IL-12家族细胞因子（IL-12 family cytokine）——在Treg调控T细胞诱导性结肠炎的过程中发挥关键作用。与能够抑制致结肠炎T细胞扩增及炎性细胞因子表达的野生型（WT）Treg不同，IL-27受体缺陷型Treg无法下调炎性T细胞的免疫应答。经IL-27刺激的Treg，其体外与体内的抑制功能均显著增强。IL-27刺激Treg可诱导淋巴细胞活化基因3（LAG3）的表达，该表面分子被证实可负向调控免疫应答。IL-27刺激的Treg中，LAG3的表达对于介导Treg的抑制功能至关重要。最后，人类Treg在接受IL-27刺激后，其抑制功能与LAG3的表达同样得到显著提升。综上，本研究结果揭示了IL-27/LAG3信号轴在Treg调控肠道炎性应答中的全新功能。本研究通过荧光激活细胞分选术（Fluorescence-Activated Cell Sorting, FACS）纯化Foxp3阳性Treg，分别在普通培养基或IL-27的刺激条件下体外培养，以对比IL-27诱导的基因表达谱。本研究从4项独立实验中获取4份样本，每份样本分别经培养基刺激或IL-27刺激。将经IL-27处理的Treg的基因表达情况与培养基刺激组的Treg进行对比分析。