Antigenic stimulation in conjunction with cytokine is required for mediating IL-17A production in human MAIT cells

Mucosal-associated invariant T (MAIT) cells are donor unrestricted T cells capable of both antigen-specific adaptive responses and cytokine driven innate-like functions. Although human MAIT cells uniformly express RORgammat and IL23R, they generally produce IFN-gamma, and only a small fraction produces IL-17. Recent studies show that combined TCR and cytokine stimulation can elicit functional heterogeneity in blood-derived MAIT cells. Here, we investigate the role of IL-23/IL-23R signaling in mediating the function and transcriptional profiles of lung MAIT cell clones. We demonstrate that BAL-derived lung MAIT cell clones exhibit distinct cytokine profiles and variable IL23R expression. Short-term IL-23 stimulation triggers clone-specific transcriptional programs and IL23R-dependent upregulation of type 17-associated genes. Prolonged conditioning of lung MAIT cell clones with TCR (5-OP-RU) and cytokine (IL-23) stimulation induces stable IL-17A production along with unique transcriptional changes. TCR + IL-23 conditioning alone upregulates clone-specific and shared cytoskeletal/structural gene programs, whereas subsequent PMA/Ionomycin stimulation further induces IL-12 family signaling and metabolic genes. Together, these findings demonstrate that IL23R expression and TCR signaling are required for IL-17A production, highlighting that these conditions may be met in tissue environments where MR1-specific antigens and proinflammatory cytokines coexist.

黏膜相关恒定T细胞（mucosal-associated invariant T cells, MAIT）是一类不受供体限制的T细胞，既可介导抗原特异性适应性免疫应答，又可执行细胞因子驱动的类天然免疫功能。尽管人类MAIT细胞均表达视黄酸相关孤儿受体γt（RORγt）与白细胞介素23受体（IL-23R），但其主要分泌干扰素γ（IFN-γ），仅少数亚群可产生白细胞介素17（IL-17）。近期研究表明，联合T细胞受体（T cell receptor, TCR）与细胞因子刺激可诱导血液来源MAIT细胞产生功能异质性。本研究探讨了IL-23/IL-23R信号通路在调控肺MAIT细胞克隆的功能与转录谱中的作用。研究发现，支气管肺泡灌洗液（bronchoalveolar lavage, BAL）来源的肺MAIT细胞克隆呈现独特的细胞因子分泌谱与可变的IL-23R表达水平。短期IL-23刺激可触发克隆特异性转录程序，并以IL-23R依赖的方式上调17型相关基因的表达。采用T细胞受体配体5-OP-RU与细胞因子IL-23对肺MAIT细胞克隆进行长期预处理，可诱导其稳定分泌IL-17A，并伴随独特的转录组改变。仅经TCR+IL-23预处理即可上调克隆特异性及共有的细胞骨架/结构基因程序，而后续经佛波醇12-肉豆蔻酸13-乙酸酯（phorbol 12-myristate 13-acetate, PMA）与离子霉素（ionomycin）刺激可进一步诱导IL-12家族信号通路与代谢相关基因的表达。综上，本研究证实IL-23R表达与TCR信号通路是IL-17A产生的必要条件，提示在MR1特异性抗原与促炎细胞因子共存的组织微环境中，可满足此类调控所需的条件。