Cyclooxygenase-2 and prostaglandin E2 in vitiligo patients: plasma and tissue levels

Background Vitiligo is an acquired depigmenting disorder characterized by the selective destruction of melanocytes. Cyclooxygenases (COXs) are key enzymes in the conversion of arachidonic acid into prostaglandins. COX-2 expression plays a major role in prostaglandin E2 (PGE2) production. PGE2 plays an important role in tyrosinase activation and melanogenesis. Objective To determine the possible role of COX-2 and PGE2 in the pathogenesis of vitiligo. Patients and methods This analytic cross-sectional study included 22 vitiligo patients and 20 controls. Two skin biopsies were obtained from depigmented lesions and clinically normal skin from patients and one skin biopsy from the controls. COX-2 gene expression was semiquantified in skin biopsies using a reverse transcriptase-PCR and the PGE2 level was determined by an enzyme-linked immunosorbent assay. Blood samples were withdrawn from patients and controls to assess the plasma levels of PGE2 and COX-2 using the enzyme-linked immunosorbent assay technique and COX-2 activity using the Cyclooxygenase Enzyme Immunometric Assay Kit. Results The expression of COX-2 mRNA was significantly decreased in lesional and nonlesional skin of patients compared with the controls (Po0.001). In addition, the level of PGE2 was significantly decreased in lesional and nonlesional skin of patients compared with the controls (Po0.001, P= 0.003, respectively). The plasma levels and activity of COX-2 and the levels of PGE2 were significantly elevated in patients compared with the controls (Po0.001). Conclusion COX-2 and PGE2 could contribute toward the development of vitiligo through their immunomodulatory role or locally through their role in melanogenesis.