Biological effects of a new ultraviolet A1 prototype based on light-emitting diodes on the treatment of localized scleroderma.

ABSTRACT

Ultraviolet A1 (UVA1 ) phototherapy (spectral range 340-400 nm) is a well-established treatment option for various skin diseases such as localized scleroderma. Recent improvements of conventional UVA1 light sources (metal-halide or fluorescent lamps) have brought attention to a new light-emitting diode (LED) technology with remarkable advantages in handling and clinical routine. This study provides a preclinical histological and molecular evaluation of an LED-based UVA1 prototype with a narrower spectral range (360-400 nm) for treating localized scleroderma. Scleroderma mouse models and fibroblasts in vitro were exposed to LED-based UVA1 phototherapy or to irradiation with a commercially available metal-halide lamp emitting low-dose (20, 40 J/cm2 ), medium-dose (60 J/cm2 ) and high-dose (80, 100 J/cm2 ) UVA1 light. Both UVA1 light sources affected inflammatory genes (IL-1α and IL-6) and growth factors (TGFß-1 and TGFß-2). Increased collagen type 1 was reduced after UVA1 phototherapy. Matrix metalloproteinase-1 was more enhanced after a medium dose of LED-based UVA1 phototherapy than after conventional treatment. In vivo, dermal thickness and the amount of collagen were reduced after both treatment methods. Remarkably, myofibroblasts were more effectively reduced by a medium dose of LED-based UVA1 phototherapy. The study indicates that LED-based UVA1 phototherapy yields similar or even better results than conventional treatment. In terms of biosafety and patient comfort, LED-based UVA1 phototherapy offers clear advantages over conventional treatment because of the use of a narrower and less harmful UVA1 spectrum, less heat generation and shorter treatment times at the same irradiation intensity. Clinical studies are required to confirm these results in patients with localized scleroderma.