Suppressive effect of an aqueous extract of Diospyros kaki calyx on dust mite extract/2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions.

Atopic dermatitis (AD) is a common chronic inflammatory skin disease, affecting 10-20% of individuals worldwide. Therefore, the discovery of drugs for treating AD is an attractive subject and important to human health. Diospyros kaki and Diospyros kaki (D. kaki) folium exert beneficial effects on allergic inflammation. However, the effect of D. kaki calyx on AD remains elusive. The present study evaluated the effects of an aqueous extract of D. kaki calyx (AEDKC) on AD-like skin lesions using mouse and keratinocyte models. We used a mouse AD model by the repeated skin exposure of house dust mite extract [Dermatophagoides farinae extract (DFE)] and 2,4-dinitrochlorobenzene (DNCB) to the ears. In addition, to determine the underlying mechanism of its operation, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ)-activated keratinocytes (HaCaT) were used. Oral administration of AEDKC decreased AD-like skin lesions, as demonstrated by the reduced ear thickness, serum immunoglobulin E (IgE), DFE-specific IgE, IgG2a, histamine level and inflammatory cell infiltration. AEDKC inhibited the expression of pro-inflammatory cytokines and a chemokine via downregulation of nuclear factor-κB and signal transducer and activator of transcription 1 in HaCaT cells. On examination of the AD-related factors in vivo and in vitro, it was confirmed that AEDKC decreased AD-like skin lesions. Taken together, the results suggest that AEDKC is a potential drug candidate for the treatment of AD.