Downregulation of aquaporin 3 in bullous pemphigoid patients.

Bullous pemphigoid (BP) is a chronic autoimmune skin disease. Aquaporin 3 (AQP 3) has a possible role in the pathogenesis of many dermatological diseases. In this work, we aimed to evaluate the expression of AQP 3 in BP. Perilesional skin biopsies were taken from 24 BP patients and 13 controls. The biopsies were stained by direct immunofluorescence using rabbit anti-human AQP 3 FITC antibody. The expression of AQP 3 was weak in 5 patients (20.8%), moderate in 18 patients (75%), strong in 1 patient (4.2%) in the suprabasal layers. It was negative in 4 patients (16.7%), weak in 18 patients (75%), moderate in 2 patients (8.3%) and no strong fluorescence was seen in the basal layers. In the controls, the expression was strong in ten controls (76.9%), moderate in three controls (23.1%) and no controls showed weak fluorescence in the suprabasal layer. The basal layer showed strong fluorescence in 11 controls (84.6%), moderate in 2 controls (15.4%) and no controls showed mild or no fluorescence. There was a statistically significant difference in the expression of AQP 3 between basal and suprabasal layers of BP patients but not of the controls. There was statistically significant difference in the expression of AQP 3 between patients and controls in both the basal (P value < 0.001) and the suprabasal layers (P value < 0.001). In conclusion, AQP 3 was downregulated in BP patients especially in the basal cell layer. This suggests that AQP 3 plays a role in the pathogenesis of BP.