Background Narrowband ultraviolet A1 (UVA1) phototherapy implications for systemic sclerosis still remain the area of research.
Objectives To define the efficacy and safety of 365±5 nm UVA1 for the dermal fibrosis treatment in bleomycin-induced mouse model of scleroderma.
Methods DBA/2 strain mice were randomly divided to 6 groups: I – healthy animals$;$ II – control group with bleomycin induced scleroderma, III and IV – mice with established scleroderma, treated with high and medium dose of UVA1, V and VI – healthy mice, treated with high and medium dose of UVA1. Scleroderma model was induced according to the protocol . Light source emitting a narrowband UVA1 of 365±5 nm and of 21 mW/cm2 power density was used in the study. Phototherapy was performed 3 times weekly for 5 weeks. The average cumulative doses were 1200 J/cm2 for high and 600 J/cm2 for medium dose treatments. Histological analysis with hematoxylin-eosin staining for dermal thickness measurement was performed. The immunohistochemical staining for p53, Ki-67 and active caspase-3 proteins was performed using specific antibodies. Statistical significance was expressed by a P value <0.05.
Results The dermal thickness of mice treated with high and medium dose of UVA1 was significantly reduced to 272.9±113.2 and 394.0±125.9 μm, respectively, in comparison to the control group II (599.0±55.7 μm). The percentage of Ki-67 positive cells in mice with scleroderma after high- and medium-dose of UVA1 did not differ from the control group (II). The expression of p53 was significantly higher in the skin of the control group (II) compared to that of healthy mice skin (group I). After treatment of mice with scleroderma with high- and medium-dose of UVA1, the expression of p53 in the dermal layers did not differ from the control group (II) of non-treated mice. There was no change of p53 nor Ki-67 expressions between healthy (group I) and UVA1-treated healthy mice skin (groups V and VI). The statistically significant increase of active caspase-3 expression in the skin of mice with scleroderma was present after high- and medium-dose of UVA1 (groups III and IV) as compared to that of non-treated mice group (II). The expression profile of active caspase-3 did not differ between healthy (group I) and UVA1-treated healthy mice skin (groups V and VI). Results are summarized in Table 1 (Ki-67) and Figure 1 (A - active caspase-3; B - p53 immunohistochemical analysis).
Conclusions The cumulative doses of 1200 J/cm2 and 600 J/cm2 of narrowband UVA1 effectively reduced the dermal thickness, and the impact was dose-dependent. Phototherapy course did not up-regulate p53 nor Ki-67 proteins in the healthy mice and mice with scleroderma skin. UVA1 radiation caused the increase of the active caspase-3 expression in the skin of mice with scleroderma reflecting the apoptotic feature of narrowband UVA1. The results of this study indicate that 365±5 nm UVA1 phototherapy is safe and effective for the treatment of dermal fibrosis.
Avouac J. Mouse model of experimental dermal fibrosis: the bleomycin-induced dermal fibrosis. Methods Mol Biol 2014; 1142: 91–8.
Disclosure of Interest None declared