Cyclosporin is a very effective treatment for severe psoriasis, but its exact mechanism of action in this disease is not completely understood. It has been hypothesized that the drug could act through (lie inhibition of the expression of certain cell adhesion molecules on the keratinocytes prior to the reduction in the number of epidermal inflammatory cells. Several studies have focused on ICAM-1 changes on keratinocytes and endothelial cells after cyclosporin treatment in psoriatic patients but their results have been somewhat contradictory. We examined changes in T-cell markers and adhesion molecules among keratinocytes, enclothelial and inflammatory cells after low-dose cyclosporin treatment for severe psoriasis.
We performed a histological and immunohistochemical study on psoriatic skin among 10 patients (7 males and 3 females; mean age 37 years) treated with low-dose (2.5 mg/kg/day) cyclosporin, prior to therapy, after 1 month, and after 3 months of treatment. The mean PASI (Psoriasis Area and Severity Index) before treatment was 23±4, 13±7 after the first month of therapy, and 8±2 at the end of the third month of therapy. Pretherapy samples showed a moderate to severe inflammatory infiltrate mainly clue to T-lymphocytes expressing a T-cell memory (UCHL-1) and helper/inducer (CD4) phenotype. Most of these cells also expressed HLA-DR and LFA-1 and ICAM-1 antigens. Alter the treatment, an overall reduction in the degree of epidermal hyperplasia was seen (p=0.01). The severity of the infiltrate was clearly reduced (p=0.05), but no significant changes in the phenotype profile were observed. Although slightly reduced, endothelial ICAM-1 expression persisted after cyclosporin therapy. Keratinocyte ICAM-1 expression was uniformly and significantly reduced after 1 month and 3 months of therapy (p=0.01). These results support the hypothesis that cyclosporin interferes with the expression of keratinocyte adhesion molecules in patients with psoriasis.