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Cell-to-cell adhesion is mediated by cadherins (integral membrane proteins), which form a complex with catenins (cytoplasmatic proteins). While E-cadherin expression has been extensively studied in many human skin diseases, less is known about the expression levels of catenins in oral blistering diseases. The purpose of this study was to evaluate the role of these proteins in the pathogenesis of acantholysis in oral pemphigus vulgaris. We evaluated by immunohistochemistry beta- and gamma-catenin expression in 7 cases of oral pemphigus vulgaris (PV) at various stages of the disease and, as controls, in 18 healthy patients. Healthy cases showed, as reported in the literature, a strong reactivity with both beta- and gamma-catenins, with the intensity of staining progressively decreasing from the spinous to the keratinised layers of epithelium, which had a prevalent cellular membrane expression. In PV patients, we detected a loss of membrane expression of these molecules with a progressive displacement of the signal toward the cytosol and, for gamma-catenin, nuclear dislocation, particularly in areas with intense acantholysis.

Catenins belong to a family of proteins that mediate the binding between intracytoplasmic domain of cadherins and cytoskeleton. Few data on distribution of beta and gamma catenins in non-neoplastic tissues are available from current literature. This study aims to evaluate distribution of beta and gamma catenins in oral epithelium.Nine formalin-fixed and paraffin-embedded samples of oral epithelium were retrieved from files of Department of Oral Pathology of the University of Naples "Federico II". These samples were tested with anti-beta and anti-gamma monoclonal antibodies revealed by standard streptavidin-biotin-peroxidase technique. Sections have been evaluated by two observers by optical microscope using a 40X objective. The number of positive cells has been evaluated using a semi-quantitative method.The results of this study show that beta and gamma catenins were mostly distributed in the upper two-thirds of oral epithelial thickness, except for keratinized areas which appear negative. Basal layer is positive except for the basal side of basal cells. Keratinized layers are negative for beta and gamma catenins.In physiologic conditions staining pattern for beta and gamma catenins is almost exclusively membranous, sometimes cytoplasmic but never nuclear. This staining is well-represented even in conditions of chronic inflammation and leucoplakia.