Paeonol inhibits the development of 1-chloro-2,4-dinitrobenzene-induced atopic dermatitis via mast and T cells in BALB/c mice

Our previous studies suggested that paeonol, the active constituent of the traditional Chinese medicine Cortex Moutan, may be an effective treatment for inflammatory disorders. In the present study, the therapeutic potential of paeonol on atopic dermatitis (AD) was investigated using animal and cell experiments. AD-like lesions were induced by repeated application of 1-chloro-2,4-dinitrobenzene (DNCB) to the shaved dorsal skin of BALB/c mice, and P815 cells were used for in vitro assays. The skin lesions, serum and spleens of the mice were analyzed using lesion severity scoring, histological analysis, flow cytometry, reverse transcription-quantitative polymerase chain reaction, western blotting and ELISA, in order to investigate the anti-AD effects of paeonol. In addition, western blotting and ELISA were conducted for in vitro analysis of P815 cells. The results demonstrated that oral administration of paeonol inhibited the development of DNCB-induced AD-like lesions in the BALB/c mice by reducing severity of the lesions, epidermal thickness and mast cell infiltration; this was accompanied by reduced levels of immunoglobulin E and inflammatory cytokines [interleukin (IL)-4, histamine, IL-13, IL-31 and thymic stromal lymphopoietin], along with regulation of the T helper (Th) cell subset (Th1/Th2) ratio. Application of paeonol also reduced the protein expression levels of phosphorylated (p)-p38 and p-extracellular signal-regulated kinase (ERK) in skin lesions. In vitro, paeonol reduced the expression levels of tumor necrosis factor- and histamine in P815 cells, and inhibited p38/ERK/mitogen-activated protein kinase signaling. The present findings indicated that paeonol may relieve dermatitis by acting on cluster of differentiation 4(+) T and mast cells; therefore, paeonol may represent a potential therapeutic strategy for the treatment of allergic inflammatory conditions via immunoregulation.