Reciprocal altered expression of E-cadherin and P-cadherin in mucous membrane pemphigoid.

E- and P- cadherins are involved in the selective adhesion of epidermal cells. To gain insight into the role of cadherins on the acantholysis of keratinocytes and further investigate the pathogenesis of Mucous Membrane Pemphigoid, we examined the expression of P-cadherin and E-cadherin, in normal human oral mucosa, lesional and peri-lesional mucosa in MMP. Twenty-nine samples from paraffin-embedded specimens of MMP were used for the study. Five specimens of healthy oral mucosa were evaluated as control group. To evaluate the E- and P-Cadherin expression, a mean percentage of positive cells was determined from the percentage of positive cells derived from the analysis of 100 cells in ten random areas at x400 magnification. It was observed that E-cadherin was weakly and discontinuously expressed on the epithelial layers of pemphigoid mucosa, while it was intensively expressed on all keratinocytes in normal human skin. In contrast, P-cadherin was strongly expressed throughout the entire epidermal layer in MMP samples, although its expression is restricted to the basal cell layer in normal human skin. Statistical analyses showed that the percentage of E-cadherin positive cells in the epithelium of pemphigoid cases was significantly decreased compared with that in normal human mucosa. There was a significant increase in the percentage of P-cadherin positive cells in the epithelial layers of MMP compared with normal human mucosa. The present study showed that there is downregulation of E-cadherin expression and upregulation of P-cadherin expression in MMP mucosa, which may be involved in the pathogenesis of MMP.