Epithelial expression of cytokeratins 15 and 19 in vitiligo.

BACKGROUND: Cytokeratins (CK) belong to the family of intermediate filament proteins, and among them specific epithelial keratins are considered markers for stem cells activation. OBJECTIVES: This study aims to investigate the expression of CK15 and CK19 as possible stem cell markers in vitiligo during phototherapy. METHODS: The study was conducted on vitiligo patients receiving narrow-band ultraviolet therapy. Immunohistochemical staining for CK15 and CK19 was carried out, and clinical follow-up continued for 4 weeks. RESULTS: Of 28 patients, CK15 expression was demonstrated in 17 cases (61%) while CK19 expression was demonstrated in 11 cases (39%). Cells expressing positive staining were demonstrated in follicular and interfollicular epithelium. Expression was clearly demonstrated in patients younger than 20 years old, with shorter disease duration, with disease stability, and with normally pigmented hairs. Expression of cytokeratins was significantly correlated to improvement of vitiligo lesions. CONCLUSION: CK15 and CK19 are expressed in vitiligo during UV repigmentation in the follicular and interfollicular epithelium. This expression of cytokeratins was significantly correlated to improvement and can be considered valuable tool to monitor stem cells stimulation for the sake of the repigmentation process in vitiligo.

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

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 < 0.001) and keratinocytes of psoriatic skin showed significant increased expression of P53 (P < 0.001), Fas (P < 0.001) and Bcl-2 (P < 0.001) with no significant change in Bax expression (P > 0.05). Apart from significant decrease of Bcl-2 expression (P = 0.01), no significant difference in all previous markers were encountered in lymphocytes (P53, Fas and Bax; P > 0.05) after PUVA therapy. The AI was significantly increased (P = 0.008) after PUVA therapy especially in lymphocytes (P = 0.002). CONCLUSION: The present study suggests that one of the actions of PUVA therapy in psoriasis might be exerted through induction of apoptosis especially of lymphocytes by suppression of Bcl-2 expression and of keratinocytes through P53 and Fas pathways leading to healing of psoriasis.