A double-blind, randomized quantitative comparison of calcitriol ointment and calcipotriol ointment on epidermal cell populations, proliferation and differentiation

BACKGROUND: Calcitriol and calcipotriol are widely used in the topical treatment of psoriasis. However, studies comparing both treatment modalities are scarce. Especially, there are almost no studies comparing the effects on epidermal cell populations in a quantitative manner. OBJECTIVES: The aim of this study was to quantitatively compare the effects of topical calcitriol and topical calcipotriol on clinical scores and epidermal subpopulations. PATIENTS AND METHODS: From five patients with stable plaque psoriasis, skin biopsies were taken from two symmetrical regions on the trunk or extremities before and after treatment with either calcitriol or calcipotriol. Frozen sections were labelled immunofluorescently using direct immunofluorescence for beta-1 integrin and the Zenon labelling technique for keratin (K) 6, K10 and K15. The digital photographs of the stained sections were quantitatively analysed and the results of both treatments were compared. RESULTS: The clinical SUM-score improved significantly for both the calcitriol- and the calcipotriol-treated lesions. In the calcipotriol-treated group the expression of K10 and K15 increased and the expression of K6 decreased significantly. No changes were seen for the marker beta-1 integrin. In the calcitriol-treated group none of the markers changed significantly. A tendency towards significance was seen for the changes in the expression of K6 and K15 in favour of calcipotriol. CONCLUSIONS: Both calcitriol and calcipotriol gave a significant improvement in clinical scores. However, treatment with calcipotriol resulted in a normalization of K6, K10 and K15, whereas treatment with calcitriol did not. Comparison of both treatments showed a tendency towards significance for the above-mentioned markers for calcipotriol only.