Transforming growth factor-beta 1 and ultraviolet A1 radiation increase production of vascular endothelial growth factor but not endothelin-1 in human dermal fibroblasts

Background Normal and dysregulated wound healing involves fibroblast activa tion and angiogenesis, in which polypeptide factors such as transforming gr owth factor (TGF)-beta, vascular endothelial growth factor (VEGF) and endot helin-1 (ET-1) play an important part. Ultraviolet (UV) A1 (365 nm) has rec ently received attention as a possible treatment for some dermal fibrotic d isorders. Objectives The aim of this study was to evaluate the effects of TGF-beta 1 and UVA1 radiation, as well as that of cobalt chloride, reported to mimic h ypoxia both in vivo and in vitro, on the expression of VEGF and ET-1 by cul tured human dermal fibroblasts. Methods Levels of VEGF and ET-1 were measured by enzyme-linked immunosorben t assay and expression of neutral endopeptidase (NEP, CD10), known to degra de ET-1, was quantified by flow cytometric analysis after cell trypsinizati on. Results Our results showed that the cells released minor amounts of VEGF an d ET-1. Both TGF-beta 1 and UVA1 strongly increased VEGF secretion in a dos e- and time-dependent manner, without significantly affecting ET-1 release, Irradiation of TGF-beta 1-stimulated fibroblasts resulted in a synergistic effect on increasing levels of VEGF but not ET-1 after 48 h. Cobalt chlori de stimulated the secretion of VEGF by fibroblasts; the effects of TGF-beta 1 and cobalt were additive, However, no significant effect of cobalt chlor ide on ET-1 secretion was observed, suggesting that ET-1 production in fibr oblasts is not oxygen-sensitive. The expression of NEP was not modified by TGF-beta 1 or UVA1 radiation, Addition of a neutralizing anti-CD10 antibody to fibroblast cultures downregulated CD10 expression at the cell surface w ithout changing ET-1 levels in cell supernatants after 24 or 48 h, This sug gests that membrane-bound NEP has minimal or no activity against secreted E T-1. Conclusions Taken together, these results underline the major role played b y TGF-beta 1 in increasing VEGF secretion by fibroblasts. This, as well as the documented effect of UVA1 on increasing VEGF production, may have impli cations for wound healing in vivo.