Psoriasis vulgaris is a common skin disorder characterized by focal formation of inflamed, raised plaques that constantly shed scales derived from excessive growth of skin epithelial cells. Cell-cycle progression is normally regulated by cyclins and cyclin-inhibiting proteins. Progression of cells from the G1 to the synthesis (S) phase is regulated through the product of the retinoblastoma tumor suppressor gene (pRb) phosphorylation by cyclin D complexed with cyclin-dependent kinases. It was reported that the proliferating cell population is approximately doubled in psoriasis, whereas the cell cycle is more than eight times shorter. Recently, cyclin D1 has been considered as one of the possible factors in psoriasis pathogenesis, but its role has not been not well established.Objective
The aim of the study was to assess the expression of cyclin D1 in psoriasis, to evaluate its role in the pathogenesis of psoriasis and to evaluate the effect of phototherapy on its expression.Materials and methods
The study included 30 patients with psoriasis vulgaris and 10 healthy age and sex-matched controls. Patients were treated with 24 sessions of either narrowband ultraviolet B or psoralen ultraviolet A. Skin biopsies were taken from the affected skin of each patient before and after treatment and from the healthy controls, for cyclin D1 expression using immunohistochemistry.Results
The mean value of cyclin D1 expression in patients before phototherapy was significantly greater than that in controls, and we detected a significant decrease in cyclin D1 expression after phototherapy in the diseased group.Conclusion
Cyclin D1 upregulation may play a role in the pathogenesis of psoriasis. Downregulation of cyclin D1 may be a mechanism by which phototherapy induces remission in psoriasis.