Expression of vitamin D receptor in cultured human keratinocytes and fibroblasts is not altered by corticosteroids

Topical vitamin D-3 therapy is one of the mainstays of psoriasis treatment. However, the effectiveness of combination therapy with topical vitamin D-3 and corticosteroids is still controversial. It has been reported that topi cal vitamin D-3 treatment following topical corticosteroids is less effecti ve than that without preceding corticosteroid treatment. We hypothesized th at vitamin D receptor (VDR) in the skin is down-regulated by topical cortic osteroids. To obtain support for this hypothesis, we determined VDR protein levels in cultured keratinocytes and fibroblasts after corticosteroid trea tment. VDR levels were quantified by Western blot analysis with a FluoroIma ger. Keratinocytes and fibroblasts were obtained from four psoriasis patien ts and four normal controls. VDR levels were altered in neither normal nor psoriatic keratinocytes by 2-day incubation with dexamethasone (1 x 10(-9)- 1 x 10(-6) M) or clobetasol propionate (1 x 10(-9)-1 x 10(-6) M). Similarly , VDR levels in normal and psoriatic fibroblasts were not affected by 2-day incubation with dexamethasone (1 x 10(-6) M). These findings suggest that down-regulation of VDR by topical corticosteroids in keratinocytes and fibr oblasts of psoriasis is unlikely. (C) 1999 Elsevier Science Ireland Ltd. Al l rights reserved.