Increased insulin-like growth factor binding protein-3 expression level in psoriatic tissue before and after systemic treatment with cyclosporine A and methotrexate.

Insulin-like growth factor (IGF) and its binding proteins (BPs) are candidates to play a role in the pathogenesis of psoriasis. IGF-I and -II and their binding proteins (IGFBPs) have both growth inhibitory and mitogenic effects on a multitude of cell types. Current studies have explored the potential role of IGFBP-3 in keratinocyte growth and differentiation. To gain more insight into the role of IGFBP-3 in the pathogenesis of psoriasis, we investigated the changes in IGFBP-3 expression levels in psoriatic plaque and compared these expressions with levels in other inflammatory skin diseases. In particular, we investigated whether or not the changes in IGFBP-3 were affected by systemic treatment with cyclosporine A (CsA) or methotrexate (Mtx). We found significantly increased IGFBP-3 expression levels in the psoriatic group compared with levels in patients with other, nonproliferative inflammatory skin diseases, and we demonstrated differences in distribution pattern before and after systemic treatment with Mtx or CsA. Mtx and CsA had no effect on tissue IGFBP-3 expression levels. Before treatment with Mtx or CsA, IGFBP-3 expression was limited to the basal layer and suprapapillary region. Unlike with Mtx, CsA significantly changed the IGFBP-3 distribution pattern.