Evaluation of apoptosis regulatory proteins in response to PUVA therapy for psoriasis

Summary Background The histopathologic changes characteristic of psoriasis might be related to suppressed apoptosis. One of the actions of psoralen ultraviolet A (PUVA) in psoriasis could be exerted through induction of apoptosis of keratinocytes and lymphocytes; however, its exact molecular mechanism is still confusing. Aim In this study, we evaluated the expression of pro‐apoptotic (P53, Fas and Bax) and anti‐apoptotic (Bcl‐2) proteins correlating it with apoptotic index (AI) and epidermal thickness in psoriatic skin before and after PUVA therapy. Methods Lesional and non‐lesional skin biopsy specimens were obtained from 10 patients with generalized plaque psoriasis before and after 8 weeks of PUVA therapy. Histometric measurements of epidermal thickness as well as P53, Fas, Bax and Bcl‐2 expressions were evaluated using immunoperoxidase technique and apoptotic cells were detected by terminal deoxynucleotide transferase (TdT) mediated deoxyuridine triphosphate nick end labeling (TUNEL) method. Results After PUVA therapy, the epidermal thickness of psoriatic skin was significantly decreased (P