Significance Of Immunoreaction And Cell Apoptosis In Oral Lichen Planus

Objective: To evaluate the expression of Smad7, Smad4, TGF-β1, CD4+and CD8+T lymphocytes and the changes of the ratio of CD4/CD8 in oral lichen planus(OLP), and to investigate the role and the relationship of immunological reaction and cell apoptosis in the pathogenesis of oral lichen planus.Methods: Immunohistochemical technique was employed to study the expression of CD4+,CD8+Tcells in specimen from 27 OLP cases and 10 normal oral mucosa (NOM) cases, and the expression of Smad7 ,Smad4, TGF-β1 in 17 OLP cases and 5 NOM cases. TUNEL was used for detecting the cell apoptotic index (AI) in 17 OLP cases. All OLP cases were divided into erosion-atrophy group (13 cases) and non-erosion group (14 cases) according to their clinical features.Results: The amount of CD8+ (35.57±4.25) and CD4+ (17.81±5.13) T cells are obviously elevated in lamina propria of OLP group compared with CD8+ (7.57±3.14) and CD4+ (10.68±4.81) in the NOM(P<0.05). There is a strong significance (P<0.05) when compared the ratio of CD4/CD8 in both group. AI was remarkably increased in epithelia cells (14.26±2.32) and significantly decreased in lymphocytes in lamina propria (8.52±2.34) in OLP cases compared with its expression in the NOM (6.69±0.64) and (20.14±7.27) respectively. The mean stain of TGF-β1 (0.4839±0.2545), Smad7 (0.5852±0.2504) and Smad4(0.3681±0.1827) were analyzed in OLP epithelia cells, in which TGF-β1 and Smad7 demonstrated a strong significance(P<0.05) compared the NOM, but their expression in erosion-type and non-erosion-type of OLP showed no significant difference (P>0.05). The amount of CD8+ T cells in OLP was positively correlated with pathological development of OLP(r=0.553,P<0.05),while it has a negative relationship with cell apoptosis of lymphocytes(r=-0.674,P<0.05).There is a positive correlation between TGF-β1 expression and cell apoptosis in epithelial cells (r=0.691,P<0.05).Conclusion: The increased amount of CD4+, CD8+T cells in lamina propria of OLP and the change of ration of CD4/CD8 suggest that immune response is involved in the pathogenesis of OLP. There is a significant difference of cell apoptotic index between epithelial cells and lymphocytes in lamina propria in OLP, which indicated the abnormal cell apoptosis plays an important role in the pathogenesis of OLP. The high expression of Smad7 and TGF-β1 in OLP showed that TGF-β1/Smad normal pathway was disturbed. Elevated production with low apoptosis in CD8 + T cells in lymphocytes and high expression of TGF-β1 in epithelial cells together with the imbalance of TGF-β1/Smad pathway may all contribute in the mechanisms of cell apoptosis of epithelial cells in OLP. Dysfunctional immune response and abnormal cell apoptosis may play important roles in the pathogenesis of OLP.