T cell-derived exosomes induced macrophage inflammatory protein-1α/β drive the trafficking of CD8 T cells in oral lichen planus.

Oral lichen planus (OLP) is a T cell-mediated chronic inflammatory disease with uncertain aetiology. Exosomes are nanosized particles with biological capacities. Here, we aimed to study the effects of T cell-derived exosomes (T-exos) on the pathogenesis of OLP and its mechanism. T-exos were incubated with Jurkat cells for 48 hours, and 26 cytokines in the supernatant were measured by luminex assay. The expression of macrophage inflammatory protein (MIP)-1α/β was detected using immunohistochemistry and ELISA; that of CCR1/3/5 on peripheral T cells was determined by flow cytometry. Transwell assay was performed to investigate the chemotactic effect of MIP-1α/β, and cells in the lower chambers were examinated by flow cytometry. As a result, OLP T-exos elevated the production of MIP-1α/β, which were highly expressed in OLP tissues and plasma. CCR1/5 were markedly expressed on OLP peripheral T cells, and the majority of CCR1/5 T cells were CD8 T cells. Besides, MIP-1α/β promoted the migration of OLP mononuclear cells, while inhibiting CCR1/5 significantly decreased the trafficking of mononuclear cells, especially that of CD8 T cells. Conclusively, OLP T-exos-induced MIP-1α/β may drive the trafficking of CD8 T cells after binding with CCR1/5 in OLP, contributing to the development of OLP.