The effect of narrowband ultraviolet B on the expression of matrix metalloproteinase-1, transforming growth factor-β1 and type I collagen in human skin fibroblasts

Background: Ultraviolet (UV) irradiation induces chronic skin diseases, such as skin cancer and photoageing, and the mechanisms of this skin damage are associated with the upregulation of matrix metalloproteinases (MMPs) and decreased collagen synthesis. Narrowband ultraviolet B (NB-UVB) radiation is a relatively new treatment modality for vitiligo and psoriasis. However, the mechanism of NB-UVB action on photoageing is not completely understood. Aims: We investigated the effects of NB-UVB on the expression of MMP-1, transforming growth factor (TGF)-beta 1 and type I collagen in cultured human skin fibroblasts. Methods: Cultured human fibroblasts were irradiated with either NB-UVB (50-800 mJ/cm(2)) or broadband UVB (BB-UVB; 25 mJ/cm(2)). The expression of MMP-1, TGF-beta 1 and type I collagen mRNA was determined by reverse-transcription PCR. Expression of MMP-1 and TGF-beta 1 protein was determined by ELISA and that of type I collagen by Western blotting. Results: NB-UVB induced the expression of MMP-1 and reduced the expression of TGF-beta 1 and type I collagen at the mRNA and protein levels in a dose-dependent manner. The expression of type I collagen protein decreased more after irradiation with 25 mJ/cm(2) of BB-UVB than 400 mJ/cm(2) of NB-UVB. Conclusions: This study indicates that NB-UVB irradiation reduces type I collagen synthesis in human skin fibroblasts by inhibiting TGF-beta 1 expression and stimulating the release of MMP-1. It also suggested that the photoageing-related effects of NB-UVB are weaker than those of BB-UVB in vitro.