Antiphotoaging Effects of Light‐Emitting Diode Irradiation on Narrow‐Band Ultraviolet B–Exposed Cultured Human Skin Cells

Background Antiaging effects of light‐emitting diodes (LEDs) have been clinically demonstrated using one or two wavelengths. The mechanism is unclear. Objective To examine direct and indirect photobiomodulation effects of LEDs on narrow‐band ultraviolet B (NB‐UVB)‐induced photoaging using seven different wavelengths alone or in combination. Materials and Methods Four LED wavelengths were chosen based on type I collagen and metalloproteinase (MMP)‐1 expression. NB‐UVB‐irradiated fibroblasts or keratinocytes were irradiated using these four wavelengths. The expression of collagen and MMP‐1 in fibroblasts with or without conditioned medium from LED‐irradiated keratinocytes and the expression of proinflammatory cytokines in the LED‐irradiated keratinocytes were examined. Results Irradiation with four wavelengths (630, 660, 830, and 850 nm) significantly increased the number of viable fibroblasts. These four wavelengths also increased type I collagen expression, particularly four combinations (630/830, 660/850, 630/850, and 660/830 nm). The fibroblasts cultured with the keratinocyte conditioned medium, particularly with a combination of 630/850 or 660/830 nm, increased collagen levels. Low tumor necrosis factor alpha (TNF‐α) and high transforming growth factor beta 1 (TGF‐β1) expression was detected in the LED‐irradiated keratinocytes. Conclusion The combination of 630/850‐ or 660/830‐nm irradiation led to better direct and indirect antiphotoaging outcomes than single LED wavelengths in NB‐UVB‐irradiated cultured normal human skin cells.