Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Dermatology and Venerology

This study included forty patients with psoriasis, twenty patients received PUVA and the other twenty received retinoids. Twenty healthy , age and sex matched, controls were also included. Each patient was subjected to short medical history and cutaneous examination. Skin biopsies from the lesional and perilesional skin of each case were examined and immunohistochemical study was done using anti aquaporin 3 antibodies before and after treatment with PUVA and retinoids.The same was applied to biopsies from healthy controls.Results: AQP3 stained both the psoriatic and normal epidermis in both the basal and spinous layers. No staining reaction was detected within the stratum corneum in all cases and controls. Among psoriasis patients, there were a significantly higher number of biopsies showing cytoplasmic pattern of AQP3 in the spinous layers compared to control (P value = <0.001). Moreover, the cytoplasmic expression of AQP3 in the spinous layer was also significantly higher than control (P value = < 0.001). Exposure to PUVA didn{u2018}t cause significant change in the membranous as well as the cytoplasmic expression of AQP3 in the lesional skin. Retinoids reduced the cytoplasmic expressions of AQP3 to approach normal control values. Conclusion: In psoriatic epidermis, the abnormal cytoplasmic location of AQP3 may affect its function and together with its over expression may lead to increased TEWL and dryness of the lesion. The high expression of AQP3 can be related to hyperproliferation of the epidermis and increased T cell traficking . Treatment with PUVA didn{u2018}t affect the cytoplasmic location of AQP3. On the other hand, treatment with retinoids almost normalized the AQP3 cytoplasmic expression.This suggests that AQP3 can be a theraputic target for retinoids in psoriasis

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