★ CCL5 and CCR5 contribute to the immune response of OLP. ★ Th1-type cytokines in OLP perform as a magnifier for CCR5 expression. ★ MicroRNA-125a is down-regulated, and negatively correlates with the severity of OLP.
Oral lichen planus (OLP) is a T cell-mediated autoimmune disease of oral mucosa, in which T helper 1 (Th1) cells are greatly involved. Chemokine CCL5 is required for T cells infiltration and activation. CCR5, one of its receptors, specifically expressed on Th1 cells among CD4+ T cells, can be up-regulated by Th1 cytokines like interleukin2 (IL-2) and interferon-gamma (IFN-γ), and down-regulated by Th2 cytokines like IL-4. The present study aimed to determine whether CCL5 and CCR5 had effects on the immune response of OLP. We analyzed the proportion of CCR5+CD4+ T cells in CD4+ T cells using flow cytometry and the serum levels of CCL5, IL-2, IFN-γ, and IL-4 with ELISA. MicroRNA-125a (miR-125a), a blocker of CCL5, was examined with RT-PCR. The results showed both the serum CCL5 and the percentage of CCR5+CD4+ T cells elevated in OLP patients. Serum IL-2 and IFN-γ increased in OLP patients, but IL-4 decreased. MiR-125a was down-regulated in OLP patients, and there was a negative correlation between miR-125a content and the OLP severity which was measured with a RAE (reticular, atrophic and erosive lesion) scoring system. In conclusion, increasing CCl5/CCR5 might participate in the immune response of OLP. Th1-type cytokines environment presented in OLP probably performed as a magnifier for the CCR5. Moreover, miR-125a might be a candidate biomarker to estimate the severity of OLP.