IL-23 tunes inflammatory functions of human MAIT cells

IL-23 signaling plays a key role in the pathogenesis of chronic inflammatory and infectious diseases, yet the cellular targets and signaling pathways affected by this cytokine remain poorly understood. We show that IL-23 receptors are expressed on the large majority of human MAIT, but not of conventional T cells, suggesting that these innate-like T cells are critical mediators of IL-23 functions. In this study, we investigated the effects of IL-23 on human MAIT cell transcriptional and chromatin accessibility profiles, using RNA- and CITE-seq and ATAC-seq, respectively. Protein and transcriptional profiling at the population and single cell level demonstrates that stimulation with IL-23 or the structurally related cytokine IL-12 drives distinct functional profiles, revealing a high level of plasticity of MAIT cells. IL-23, in particular, affects key molecules and pathways related to autoimmunity and cytotoxic functions. Integrated analysis of transcriptomic and chromatin accessibility shows that AP-1 transcription factors constitute a key regulatory node of the IL-23 pathway in MAIT cells. PBMC were isolated from healthy donors. MAIT cells were activated for 6 days in PBMC cultures using MR1 tetramers loaded with 5-OP-RU (MR1/5-OP-RU), in the absence or presence of IL-23, or IL-12. After 6 days, MAIT cells were sorted and we performed RNA-seq, ATAC-seq, and CITE-seq. To identify the effects of IL-23 or IL-12 on MAIT cells, we compared cells activated in the presence of IL-23 or IL-12 with those stimulated with MR1/5-OP-RU only.

白细胞介素23（IL-23）信号通路在慢性炎症性与感染性疾病的发病机制中发挥关键作用，但该细胞因子所靶向的细胞群体及受其调控的信号通路仍未得到充分阐明。本研究证实，绝大多数人类黏膜相关恒定T细胞（mucosal-associated invariant T cells, MAIT）均表达IL-23受体，而常规T细胞则无该受体表达，这提示这类先天样T细胞是IL-23功能发挥的关键介导者。本研究分别借助RNA测序（RNA-seq）、细胞转录组与表位联合测序（CITE-seq）以及转座酶可及性测序（ATAC-seq），探究了IL-23对人类MAIT细胞转录组及染色质开放状态的影响。群体水平与单细胞水平的蛋白及转录组分析显示，IL-23或结构同源的细胞因子IL-12刺激可诱导MAIT细胞产生截然不同的功能表型，揭示了MAIT细胞具有高度的表型可塑性。尤为关键的是，IL-23可调控与自身免疫及细胞毒性功能密切相关的核心分子与信号通路。转录组与染色质开放状态的整合分析表明，AP-1转录因子家族构成了MAIT细胞中IL-23信号通路的关键调控节点。本研究从健康志愿者体内分离外周血单个核细胞（peripheral blood mononuclear cell, PBMC）；随后在PBMC培养体系中，采用负载5-OP-RU的MR1四聚体（MR1/5-OP-RU）激活MAIT细胞，并设置仅添加MR1/5-OP-RU的对照组，以及添加IL-23或IL-12的实验组，激活时长均为6天。培养6天后，我们分选得到纯化的MAIT细胞，分别开展RNA-seq、ATAC-seq及CITE-seq实验。为明确IL-23或IL-12对MAIT细胞的调控效应，我们将两组刺激条件下的细胞与仅经MR1/5-OP-RU激活的对照组细胞进行了对比分析。