Abstract
The incidence of atopic dermatitis (AD) has recently increased due to various factors. Its prevalence is higher among children and teenagers than in other age groups. Numerous methods to treat AD are available, including light ray therapy, which has been proposed as an alternative therapy for the treatment of AD. The present study aimed to evaluate the curative mechanism and optimal energy level of energy irradiation from a low-level laser (LLL) toward AD. AD was induced in BALB/c mice with dinitrochlorobenzene (DNCB) solution. The mice were divided into six groups, including one normal control (n=8), one AD control (n=10) and four AD experimental groups with LLL irradiation at 2 J/cm2 (n=10), 4 J/cm2 (n=10), 6 J/cm2 (n=9) and 8 J/cm2 (n=10). Following AD induction, an LLL was applied to the four AD experimental groups for 2, 4, 6, and 8 min, for two weeks (14 times in total) at a wavelength of 650 nm and an output of 50 mW. The effects of irradiation on AD were evaluated using a scratch test, a clinical skin severity test, immunoglobulin-E (IgE) analysis and measurements of numerous cytokine levels, including interleukin (IL)-4, IL-6, tumor necrosis factor (TNF)-α, and interferon-γ (IFN-γ), tissue thickness and mast cell count. The results demonstrated that serum IgE level in all irradiated groups was significantly decreased compared with that of the AD control group, and IL-4 level was significantly decreased in all irradiated groups apart from the 8 J/cm2 LLL irradiated group. IL-6 and TNF-α levels were also significantly decreased in all irradiated groups. The results from histological analysis revealed diminished epidermal thickness and mast cell counts in irradiated mice compared with those mice in the AD control group. In summary, these findings suggested that LLL irradiation may alleviate symptoms of AD and may be useful for restoring cytokines levels and tissues features to normal levels.