Increased B7-H1 Expression on Peripheral Blood T Cells in Oral Lichen Planus Correlated with Disease Severity

Oral lichen planus (OLP) is a chronic and T cell-mediated autoimmune disease whose immunopathogenesis may involve antigen-presentation, T cells activation and migration as well as keratinocytes apoptosis. PD-1/B7-H1 pathway may have a unique function in regulating self-reactive T cells associated with inflammatory response and maintaining tolerance in peripheral tissues. In this study, we aimed to explore the contribution of PD-1/B7-H1 pathway to OLP. We determined the expression of PD-1 and B7-H1 on peripheral blood T cells from OLP cases and analyzed their association with disease severity assessed by RAE (reticular, atrophic and erosive lesion) scoring system. In addition, interferon-gamma, interleukin (IL)-2, IL-4, IL-10 and soluble PD-1 concentrations in serum were measured using ELISA. Then, we explored the regulation of PD-1/B7-H1 pathway on T cells immune response in OLP by blockade of PD-1 or B7-H1. We found that PD-1 and B7-H1 were up-regulated on peripheral blood T cells from OLP patients and B7-H1 expression positively correlated with disease severity of OLP. It is suggested that Th1 dominant inflammatory situation might contribute to the high expression of PD-1 and B7-H1 in OLP. Blockade of PD-1/B7-H1 pathway significantly increased the proliferation, and IFN-gamma and IL-2 production of T cells. PD-1/B7-H1 pathway may play an important role in negatively modulating T cell-mediated immune response in OLP, and provide the rationale to employ B7-H1 expression on peripheral blood T cells as a marker of severity of OLP and to develop agonists targeting PD-1/B7-H1 pathway as a promising immunotherapeutic strategy for OLP.