Inhibitory effects of Juglans mandshurica leaf on allergic dermatitis-like skin lesions-induced by 2,4-dinitrochlorobenzene in mice

Allergic dermatitis among common skin diseases is a chronic and recurrent inflammatory skin disorder caused by genetic, environmental, allergens as well as microbial factors. Allergic dermatitis patients clinically present skin erythematous plaques, eruption, elevated serum immunoglobulin E (IgE) and T helper cell type 2 (Th2) cytokine levels. The leaf of walnut tree Juglans mandshurica Maxim (JM) is consumed food and traditional phytomedicine in Asia, China, Siberia and Korea. JM has been reported to have various pharmacological activities, such as anti-tumor, anti-oxidative, and anti-bacterial effects. However, no study of the inhibitory effects of JM on allergic dermatitis has been reported. Here, we demonstrated the effect of JM against 2,4-dinitrochlorobenzene-induced allergic dermatitis-like skin lesions. 0.5% JM or 1% dexamethasone (positive control) applied to the dorsal skin inhibited development of allergic dermatitis-like skin lesions and scratching behavior. Moreover, the Th2-mediated inflammatory cytokines IgE, tumor necrosis factor-α, interleukin (IL)-1, and IL-13, were significantly reduced by JM treatment. Thus JM can inhibit development of allergic dermatitis-like skin lesions in mice by regulating immune mediators, and may be an effective alternative therapy for allergic dermatitis.