Abstract: Objective To evaluate the effects of UVA and UVA-1 irradiation on type Ⅰ collagen (COL1A1) synthesis and matrix metalloproteinase 1 (MMP-1) expression by fibroblasts from patients with localized scleroderma (LS).Methods Fibroblasts were isolated from the lesions of 6 patients with LS and normal skin of 4 healthy human controls followed by a primary culture in vitro.After 3 to 8 passages,the fibroblasts were irradiated with different doses of UVA-1 (0,2.5,5,10,20,40 J/cm2) and UVA (5 and 20 J/cm2).After additional 24-hour culture,RNA was extracted from the cells followed by fluorescence-based quantitative reverse transcription PCR for the detection of MMP-1 and COL1A1 mRNA expression.Results Compared with control skin fibroblasts,LS-derived fibroblasts showed a higher expression level of COL1A1 but a lower level of MMP-1 (both P < 0.05).The irradiation with UVA-1 of the tested doses (2.5-40 J/cm2) had no significant influence on the expression of COL1A1 mRNA (all P > 0.05),but significantly increased the expression of MMP-1 mRAN (all P < 0.05).The effect of UVA on COL1Al synthesis and MMP-1 expression appeared superior to that of UVA-1 at the same doses (5 and 20 J/cm2).Conclusions UVA-1 irradiation can suppress the synthesis of COL1A1,but stimulate the expression of MMP-1,in LS-derived fibroblasts,and the effect of medium dose UVA-1 seems superior to that of low dose UVA-1.At same irradiation doses,UVA shows a stronger effect than UVA-1.