Mechanisms underlying MAIT cell ability to promote skin wound repair

Tissue repair processes maintain proper organ function following mechanical or infection related damage. In addition to anti-bacterial properties, MAIT cells express a tissue repair transcriptomic program and promote skin wound healing when expanded. Herein, we use a human-like full-thickness skin excision mouse model to assess the underlying mechanisms of MAIT cell tissue repair function. Single-cell RNAseq analysis suggests that skin MAIT cells already express a repair program at steady state. Following skin excision, MAIT cells promote keratinocyte proliferation thereby accelerating healing. Using skin grafts, parabiosis and adoptive transfer experiments, we show that MAIT cells migrate into the wound from other tissues in a TCR independent but CXCR6 dependent manner. Amphiregulin secreted by MAIT cells following excision promotes wound healing. The repair function is independent of sustained TCR stimulation. Overall, our study provides mechanistic insight into MAIT cell wound healing function in the skin. Overall design: scRNA-seq of skin MAIT cells at steady state or in skin wound repair.