Expression of TGF-beta1, Smad7 and cell apoptosis in epithelium of oral lichen planus

OBJECTIVE: To examine the expression of TGF-beta1, Smad7 and cell apoptosis in oral lichen planus (OLP) and to evaluate the possible pathogenesis of oral lichen planus. METHODS: Immunohistochemical technique was used to study the expression of TGF-beta1 and Smad7 in the epithelia cells of 17 OLP cases and 7 normal oral mucosa (NOM). TUNEL was used for detecting the cell apoptosis in 17 OLP cases and 7 NOM. RESULTS: TGF-beta1 was moderately positive in the epithelia cells of OLP. All the epithelia cells in OLP showed strong cytoplasmic staining. The expression of TGF-beta1 and Smad7 were significantly increased in OLP compared with that in NOM (P < 0.05). Cell apoptotic index (AI) was remarkably increased in epithelia cells in OLP cases, and the cell apoptosis was localized in basal and suprabasal epithelial layers. There was a positive correlation between TGF-beta1 expression and cell apoptosis in the epithelia of OLP (r = 0.69, P <0.05). CONCLUSIONS: High expression of TGF-beta1 and Smad7 in the epithelia of OLP suggests that TGF-beta1-Smad7 signal pathway was disturbed in oral lichen planus. The imbalance of TGF-beta1-Smad7 pathway may contribute to the mechanisms of cell apoptosis of epithelial cells in OLP.