Downregulation of aquaporin 3 in patients with pemphigus vulgaris.

Pemphigus vulgaris (PV) is an autoimmune bullous skin disease. Aquaporin 3 (AQP3) is a glycerol/water channel involved in several physiological functions. Evaluation of the tissue expression and localization of AQP3 in the skin of PV patients. Twenty-seven PV patients and 30 controls were included. The patients were subjected to history taking, clinical evaluation, Autoimmune Bullous Skin Disorder Intensity Score and 4-mm punch biopsy. The biopsies were stained using anti-human AQP3 antibody and the immunofluorescence pattern and intensity were evaluated using a scoring system and ImageJ software analysis. AQP3 was expressed in the basal epidermis in 27 (100%) and in the suprabasal epidermis in 19 PV patients (70.4%). It was expressed in all controls in basal and suprabasal layers. Intensity of AQP3 immunofluorescence was strong in 2 (7.4%), moderate in 19 (70.4%) and weak in 6 patients (22.2%) while it was strong in 18 (60%) and moderate in 12 controls (40%). AQP3 expression was significantly lower in patients than controls in the suprabasal epidermis (p = 0.001). Patients with extensive disease had significantly weaker AQP3 intensity than those with marked disease (p = 0.005) Downregulation of AQP3 in patients with PV, especially in the suprabasal layers and in extensive clinical disease, suggests a potential role of AQP3 in the pathogenesis of PV.