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

Background:Absent or discontinuously distributedE-cadherin across melanocyte membranes has been linked to the pathogenesis of vitiligo. Narrowband UVB (NB-UVB) is a well-known treatment modality for vitiligo thatinduces re-pigmentation by different mechansims.Topical retinoic acid in combination with topical steroids has been tried before in the treatment of vitiligo andshowed better results than topical steroids alone.Retinoic acid was found to increase cell{u2013}cell adhesion through the recruitment of cytoplasmic adhesion molecules to the cell membraneand increases the stabilization of the Ý-catenin/E-cadherin complex in the cell membrane. Aim of the study:To evaluate and compare the clinical efficacy and safety of combining systemic retinoids (Acitretin) withNB-UVB (Re-NB-UVB) against NB-UVB alone in the treatment of vitiligo and to study their effect on the expression of E-cadherin in vitiligo skin. Patients and methods:This pilot study was conducted on 20 vitiligo patients and 20 controls.10 patients received NB-UVB and 10 patients receivedAcitretin at a dose (0.3 mg/kg/day) combined with NB-UVB. Both groups received 48 sessions (three times per week) of NB-UVB. Skin biopsies (lesional and perilesional) were taken at baseline and once pigmentationoccured. Skin biopsies were preserved in formalin (10%). For clinical evaluation, VASI and VIDA scores were performed before and after treatment. All biopsies from patients and controls were stained immunohistochemically by anti E-cadherin antibody. The expression of E-cadherin in skin biopsies was assessed in all layers of the epidermis in the form of intensity, pattern and distribution. Results: Before treatment, lesional and perilesional skin showed significantly lower intensity in E-cadherin expression in comparison to control skin (p < 0.0001 and 0.0019) respectively. The focal pattern was found more frequent in lesional and perilesional biopsiescompared to control (p<0.0001and 0.0471) respectively. Absent E-cadherin expression in the granular layer was found onlyin lesional and perilesional biopsies (p =0.0067 and 0.017) respectively. There was a significant negative correlation between E-cadherin intensity in the perilesional skin and disease duration (r= -0.581, p= 0.007)

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