Immunohistochemical analysis of keratinocyte growth factor and fibroblast growth factor 10 expression in psoriasis

Abstract: The pathogenic mechanism underlying the hyperproliferation of keratinocytes in psoriasis is still not completely clarified. The production of cytokines released by activated T lymphocytes infiltrating the upper dermis probably has a crucial role. Even dermal fibroblasts can participate in the process through the secretion of growth factors, and some studies have reported an increased expression of the insulin-like growth factor 1. Few studies, however, have focused on the possible involvement of the keratinocyte growth factor (KGF/FGF-7) and the fibroblast growth factor 10 (FGF-10/KGF-2), which are secreted by fibroblasts and stimulate keratinocyte proliferation acting through a receptor specifically expressed by epithelial cells. The aim of this study was to investigate the expression of KGF and FGF-10 on the skin of patients with psoriasis by immunohistochemical analysis and to evaluate the correlation with the lymphocyte infiltrate and the epidermal proliferation. Immunostaining for KGF and FGF-10 showed that both the growth factors are upregulated in the upper dermis of psoriatic skin, and that the expression is correlated with the presence of T-cell infiltrate and with keratinocyte proliferation. Our data suggest that in psoriatic lesions activated lymphocytes can stimulate fibroblasts to produce KGF and FGF-10, which in turn contribute to sustain the hyperproliferative status of the keratinocytes.