Up-regulation of Proinflammatory Genes and Cytokines Induced by S100A8 in CD8(+) T Cells in Lichen Planus

Abstract

Lichen planus (LP) is a chronic inflammatory mucocutaneous disease. The inflammatory status of LP may be related to S100A8 (myeloid-related protein 8; MRP8) activation of cytotoxic cells. The aims of this study were to evaluate S100A8 expression in skin lesions and the in vitro effects of S100A8 on CD8(+) T cells and natural killer (NK) cells in LP. Increased levels of S100A8/S100A9 were detected in the skin lesions as well as in the sera of subjects with LP. S100A8 expression induced an increased cytotoxic response by peripheral blood CD8(+)CD107a(+) T cells as well as by NK CD56(bright) cells in patients with LP. Increased expression of interleukin (1L)-1 beta, tumour necrosis factor (TNF) and IL-6 in the CD8(+) T cells of patients with LP was induced by S100A8, in contrast to the control group that produced IL- 10 and interferon type I genes. These data suggest that, in individuals with LP, S100A8 may exert distinct immunomodulatory and cytotoxicity functions.