Abstract: Objective To investigate the effects of ultraviolet 1(UVA1)irradiation on the severity of sclerosis in a mouse model of scleroderma.Methods Mouse model of scleroderma was created by injection of bleomycin for 3 weeks.Nine of these mice were equally divided into three groups:bleomycin group receiving no irradiation,U1 group and U2 group receiving 12 minutes(5.32 J/cm²)and 25 minutes(11.1 J/cm²) of irradiation,respectively,for 20 sessions.Another 6 mice were equally divided into 2 groups,to simultaneously receive the injection of bleomycin and irradiation of UVA1 at a dose of 5.32 J/cm²(U/B1 group),or 11.1 J/cm²(U/B2 group)for 20 sessions.All the studied mice were sacrified at 2 days after the last irradiation or injection.Skin specimens were obtained from the back of these mice.Measurements of skin(epidermis and dermis)thickness,hydroxyproline content,transforming growth factor beta(TGF-β)and matrix metalloproteinases(MMP-1)expression were done using histologic and immunohistochemical methods, etc.Results Compared with the mice in bleomycin group,the skin thickness,hydroxyproline content,and expression of TGF-βwere all significantly decreased(all P<0.05),while the expression of MMP-1 was significantly increased(P<0.05)in the mice of U1 and U2 groups.However,there was no significant difference in any of the above parameters when the bleomycin group was compared with the U/B1 group or U/B2 group,or when the U/B1 and U/B2 groups were compared(all P>0.05).Conclusions UVA1 irradiation could induce the elevation of MMP-1 expression,as well as the reduction in TGF-βexpression,collagen content and skin thickness in a mouse model of scleroderma.

Key words: Scleroderma, limited, Ultraviolet ray, Transforming growth factor beta, Interstitial collagenase, Disease models, animal