Mucosal-associated invariant T (MAIT) cells are an evolutionarily conserved T cell subset, which reacts to most bacteria through T cell receptor (TCR)-mediated recognition of metabolites derived from the vitamin B2 biosynthetic pathway. Microbiota-derived signals affect all stages of MAIT cell biology including intra-thymic development, peripheral expansion, and functions in specific organs. In tissues, MAIT cells can integrate multiple signals and display effector functions involved in the defense against infectious pathogens. In addition to anti-bacterial activity, MAIT cells improve wound healing in the skin, suggesting a role in epithelium homeostasis through bi-directional interactions with the local microbiota. In humans, blood MAIT cell frequency is modified during several auto-immune diseases, which are often associated with microbiota dysbiosis, further emphasizing the potential interplay of MAIT cells with the microbiota. Here, we will review how microbes interact with MAIT cells, from initial intra-thymic development to tissue colonization and functions.

粘膜相关不变T（MAIT）细胞是进化上保守的T细胞亚群，它通过T细胞受体（TCR）介导的对维生素B2生物合成途径代谢产物的识别，对大多数细菌起反应。微生物群来源的信号影响MAIT细胞生物学的所有阶段，包括胸腺内发育，外周扩张以及特定器官的功能。在组织中，MAIT细胞可以整合多种信号并显示与防御感染性病原体有关的效应子功能。除抗菌活性外，MAIT细胞还可以改善皮肤的伤口愈合，提示通过与局部微生物的双向相互作用在上皮稳态中发挥作用。在人类中，几种自体免疫疾病会改变血液MAIT细胞的频率，通常与微生物群失调有关，这进一步强调了MAIT细胞与微生物群的潜在相互作用。在这里，我们将回顾微生物如何与MAIT细胞相互作用，从最初的胸腺内发育到组织定植和功能。