Olp-Associated Fibroblasts Stimulate Mait Cells Via Mr1 Pathway

This study aimed to examine the level and function of mucosal associated invariant T (MAIT) cells in Oral lichen planus (OLP) tissues and further explore the activation of MAIT cells by OLP-associated myofibroblasts (OLP/MFs). The expression and distribution of MAIT cells in the tissues of 18 healthy controls and 23 OLP patients were determined by immunofluorescence. Frequency, phenotype and function of MAIT cells were examined by flow cytometry. Expression of MHC class I-related protein (MR1) and MR1+fibroblasts in healthy control and OLP tissues was detected by immunofluorescence. MR1 was induced to express on the surface of OLP/MFs and co-cultured with peripheral blood monocytes, and the effect of blocking MR1 on MAIT cell activation was explored by flow cytometry. Increased MAIT cells were predominantly distributed near the basement membrane of the OLP tissue and showed elevated activation indicators (CD69, CD38, HLA-DR) and depletion phenotype (TIM-3+). The increased expression of MR1 was detected in the subepithelial lamina propria of OLP tissues, and OLP/MFs showed enhanced migration capacity and inflammatory factor expression levels by inducing MR1 expression on the surface of cells. Co-culturing of OLP/MFs and MAIT cells induced a significant upregulation of CD69+ MAIT cells, and blocking MR1 inhibited MAIT activation and cytokine secretion. Frequency of MAIT cells was elevated in OLP tissues, with increased activation phenotype and depletion phenotype. The expression of MR1 was up-regulated in OLP tissues, and OLP/MFs could activate MAIT cells via the MR1 pathway.