Structural alterations of basal keratinocytes and capillary loop in psoriasis during treatment with topical calcipotriol.

Recent research has demonstrated the activity of calcipotriol, effective as a potent inhibitor of cellular proliferation and known to increase differentiation in a number of cell lines in the topical treatment of psoriasis. Vit D3 receptors are expressed in keratinocytes and vascular endothelial cells. We studied the alterations in basal keratinocytes (stem cells or anchoring cells) and endothelial cell modification in 6 patients with psoriasis treated with calcipotriol ointment twice a day for 4 weeks. The samples were embedded in Epon resin for thin section and ultrathin section examination by electron microscopy. A normal pattern of distribution of the two different types of basal keratinocytes was observed before treatment. After treatment, only anchoring cells were detected. The alterations of endothelial cells in capillary loop disappeared after treatment, presenting normal aspects. Our morphological findings suggest that calcipotriol is therapeutically effective, due principally to an inhibition of cellular proliferation.