The Effect of PUVA Phototherapy on Bcl-2 Expression in Psoriasis Vulgaris

Background. Psoriasis is fundamentally a disease of the immune system. One of the regulatory mechanisms of the immune system is apoptosis. Blockage of the apoptotic process is one of the factors that might be implicated in the pathogenesis of psoriasis. Bcl-2 an anti apoptotic protein, is suggested to be expressed ondermal lymphocytes of psoriatic skin. As bcl-2 is considered to prevent apoptosis, it could be responsible for the chronic relapsing nature of the disease. PUVA phototherapy has been proved to treat different skin diseases by altering cytokine profiles, changing immune cytotoxicity in the skin and directly killing diseased cells by apoptosis. The apoptotic effect of PUVA phototherapy on the expression of bcl-2 in patients with psoriasis vulgaris is still unclear. Objective. To study the possible apoptotic effect of PWA phototherapy onbcl-2 expression in patients with psoriasis vulgaris. Method. Skin biopsies were taken from 15 patients with psoriasis wlgaris before and after receiving 24 sessions of PUVA phototherapy and from 10 patients withchronic non-specific inflammatory skin disease as a control group. Bcl-2 expression was imrnunohistochemically investigated within dermal lymphocytes of psoriatic skin biopsy sarnpIes before andafter PUVA phototherapy. Results. Bcl-2 expression was found to be significantly higher (p=0.017) indermal lymphocytes of psoriatic skin biopsy samples before than after PWA therapy sessions. Moreover, astatistically significant difference was found between the bcl-2 levels before therapy and those of the control group (p=0.002). There was no significant correlation between the mean value of bcl-2 (before and afterPWA phototherapy) and the age, sex, duration, extent and, PAS1 score. Conclusion. PUVA phototherapy seems to induce an evident down regulation of bcl-2 level in psoriatic patients, causing more apoptosis of the lymphocytes leading to a clinical remission of the patients.