OPN promotes survival of activated T cells by up-regulating CD44 in patients with oral lichen planus.

Oral lichen planus (OLP) is a chronic inflammatory disorder of oral mucosa, which represents cell-mediated autoimmune diseases. Pathological study demonstrated that abundant T lymphocytes infiltrated the oral mucosa, in which the activated T cells that trigger apoptosis of oral epithelial cells is an important mechanism for OLP. However, to date the molecular mechanisms underlying the T lymphocytes infiltration and accumulation in OLP remain unclear. In this paper, we found that the levels of plasma OPN were elevated and were associated with the up-regulated expressions of CD44 in OLP patients. In vitro, the addition of exogenous OPN can suppress the apoptosis of activated CD8(+) T cells via CD44, and this T cell resistance to apoptosis may be attributed to the reduction of endogenous mature granzyme B. Our results suggested that the abnormally elevated levels of OPN may contribute to the abnormal infiltration and accumulation of the activated T cells by up-regulating CD44 in OLP.