To investigate the efficacy, potential limitations, and biological mechanisms of UV-A1 phototherapy for skin sclerosis due to collagen deposition disorders.Design: Before-and-after trial of UV-A1 irradiation of sclerotic skin; in vivo biochemical analyses after UV-A1 irradiation of normal skin.Setting: Academic referral center.Participants: Patients with morphea/scleroderma or sclerodermoid graft-vs-host disease and volunteers without skin disease.Intervention: Sclerotic skin was treated with highdose (130 J/cm 2 ; n=12) or medium-dose (65 J/cm 2 ; n=6) UV-A1 phototherapy 3 times per week for 14 weeks; normal skin was treated with UV-A1 irradiation at various doses and frequencies, with biopsies performed afterwards.
Main Outcome Measures:In sclerotic skin, induration was clinically assessed using a scoring scale. In normal skin, quantitative polymerase chain reaction was used to assess antifibrotic responses, defined as decreased type I and type III procollagen and increased matrix metalloproteinase levels.Results: In patients with sclerotic skin treated with highdose UV-A1 irradiation, clinical scores for induration modestly decreased. To investigate what factors prevented further improvement (ie, complete clearance), normal skin with light pigmentation was exposed to UV-A1 irradiation (70-150 J/cm 2 ) and was assessed for antifibrotic responses. A single high-dose exposure (110-150 J/cm 2 ) elicited substantial antifibrotic responses and induced skin darkening. This skin darkening attenuated responses to subsequent UV-A1 exposures and was dose dependent. Thus, to minimize skin darkening, additional patients with sclerotic skin were treated with medium-dose UV-A1 phototherapy, which was no less effective than high-dose therapy.
Conclusion:Clinical responses of sclerotic skin to UV-A1 phototherapy were modest because of UV-A1-induced skin darkening, which is photoprotective and attenuates antifibrotic responses.