The effects of photobiomodulation therapy on inflammatory mediators, immune infiltration, and angiogenesis in a mouse model of rosacea.

Background: Rosacea is a chronic skin disorder with increasing prevalence and challenging management. Photobiomodulation therapy (PBMT) may be a promising adjuvant treatment for rosacea. Methods: This study investigated the efficacy of PBMT for the treatment of rosacea lesions in a well-established mouse model using a combination of wavelengths at 590 and 830 nm. Female BALB/c mice were randomized into three groups, namely, a negative control (NC) group, a model control (MC) group, and a PBMT group. Mice were injected with LL-37 or normal saline for construction of the model and NCs, respectively. Mice in the PBMT group were administered PBMT at wavelengths of 590 nm (25 mW) and 830 nm (50 mW). The severity of erythema, inflammatory cell counts, the expression of key inflammatory mediators, and the degree of angiogenesis and immune cell infiltration of the skin lesions were evaluated by hematoxylin and eosin (H&E) staining, immunohistochemistry, and immunofluorescence staining. Results: PBMT significantly decreased the erythema scores and inflammatory cell infiltration of rosacea lesions in mice. Further studies revealed that PBMT downregulated the increased expression of inflammatory mediators (S100A9 and p65) and angiogenesis markers (CD31), and attenuated the dysregulation of immune cell infiltration [including neutrophils, regulatory T cells (Treg cells), γδ T cells, and macrophages] in mice with rosacea. Conclusions: This investigation suggested that PBMT can improve the rosacea condition by regulating key inflammatory mediators and dysregulating immune infiltration and angiogenesis.