Local (but not systemic) photobiomodulation treatment reduces mast cell degranulation, eicosanoids, and Th2 cytokines in an experimental model of allergic rhinitis

Allergic rhinitis (AR) is an inflammatory disorder of the nasal mucosa, and is a worldwide health problem with a significant impact on the quality of life. The main goal of AR treatment is to relieve symptoms. However, standard treatments have considerable side effects or are not effective. Photobiomodulation (PBM) therapy has emerged as an alternative treatment. Here, we evaluated the effects of transcutaneous systemic (tail) or local (skin over nostrils) PBM using a 660-nm light-emitting diode (LED) array. Adult rats were assigned into 4 groups: basal, as non-manipulated animals; Sham, as rats sensitized with 7 intradermal injections of ovalbumin (OVA) plus alum followed by intranasal instillation with OVA (2%) daily for 7 days; and the LPBM and SPBM groups, in which the animals were treated with PBM (local or systemic) immediately after the last instillation of OVA (1%) daily for 3 days. Our results showed that local PBM treatment reduced mast cell degranulation in the nasopharynx and nostrils; levels of leukotriene B4, thromboxane A2, and interleukin 4 (IL-4) in the nasopharynx; and gene expression of IL-4. Moreover, we showed higher levels and gene expression of IL-10 after local PBM treatment. Systemic PBM treatment did not change any of the evaluated parameters. In conclusion, our data showed that local (but not systemic) treatment with PBM could improve parameters related to AR in an animal model, and should be tested clinically.