UVA1 irradiation inhibits fibroblast proliferation and alleviates pathological changes of scleroderma in a mouse model

The purpose of the present study was to compare the effects of different doses of ultraviolet radiation A1 （UVA1） on human fibroblast proliferation and collagen level in a mouse model of scleroderma, so as to identify appropriate irradiation doses for clinical treatment of scleroderma. Monolayer from human fibroblasts was cultured in vitro, and a mouse model of scleroderma was established by subcutaneous injection of 100 μL of 400 μg/mL bleomycin into the back of BALB/c mice for 4 weeks. The mouse models and human fibroblasts were divided into UVA1- exposed （100, 60 and 20 J/cm2） and UVA-unexposed groups. At 0, 24 and 48 h after exposure, cell proliferation and levels of hydroxyproline and collagen were detected. UVA1 irradiation was performed 3 times weekly for 10 weeks, and the pathological changes of skin tissues, skin thickness and collagen level were observed after phototherapy. Cell proliferation and the levels of hydroxyproline and collagen were inhibited after phototherapy, and there was a significant difference between the UVAl-exposed cells and UVAl-unexposed cells （P 〈 0.001）. In addition, UVA1 phototherapy improved dermal sclerosis and softened the skin, and there were significant differences between the high-dose UVA1 group and the model group, and the negative group （P 〈 0.05）. It is concluded that UVA1 radiation can reduce cell proliferation, and decrease hydroxyproline and collagen levels in a dose-dependent manner in vitro. High-dose UVA1 phototherapy has marked therapeutic effect on scleroderma in the mouse model. Decreased collagen level may be related to the reduced number and activity of cells, as well as inhibition of collagen synthesis.

Ultraviolet light A irradiation induces immunosuppression associated with the generation of reactive oxygen species in human neutrophils

Ultraviolet blood irradiation has been used as a physical therapy to treat many nonspeci¯c diseases in clinics;however,the underlying mechanisms remain largely unclear.Neutrophils,the first line of host defense,play a crucial role in a variety of in°ammatory responses.In the present work,we investigated the effects of ultraviolet light A(UVA)on the immune functions of human neutrophils at the single-cell level by using an inverted°uorescence microscope.N-Formylmethionyl-leucyl-phenylalanine(FMLP),a classic physiological chemotactic peptide,was used to induce a series of immune responses in neutrophils in vitro.FMLP-induced calcium mobilization,migration,and phagocytosis in human neutrophils was significantly blocked after treatment with 365 nm UVA irradiation,demonstrating the immunosuppressive effects of UVA irradiation on neutrophils.Similar responses were also observed when the cells were pretreated with H2O2,a type of reactive oxygen species(ROS).Furthermore,UVA irradiation resulted in an increase in NAD(P)H,a member of host oxidative stress in cells.Taken together,our data indicate that UVA irradiation results in immunosuppression associated with the production of ROS in human neutrophils.