Orostachys japonicus ethanol extract inhibits 2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions in NC/Nga mice and TNF-α/IFN-γ-induced TARC expression in HaCaT cells

The risk of atopic dermatitis (AD)-like skin lesions has increased due to the elevated levels of allergens worldwide. Natural-origin agents, which are effective and safe, show promise for the prevention and treatment of inflammatory conditions. Orostachys japonicus (OJ) A. Berger is an ingredient of traditional herbal medicines for fever, gingivitis, and cancer in Korea, China, and Japan. However, the effect of OJ on AD-like skin lesions is unknown. Therefore, we investigated the effect of OJ ethanol extract (OJEE) on AD-like skin symptoms in mice and cells. OJEE reduced the 2,4-dinitrochlorobenzene-induced AD severity, serum levels of IgE and TARC, and mRNA levels of TARC, TNF-α, and IL-4 in NC/Nga mice. Histopathological analysis showed that OJEE reduced the thickness of the epidermis/dermis and dermal infiltration of inflammatory cells in ear tissue. Furthermore, OJEE suppressed the TNF-α/IFN-γ-increased TARC mRNA level by inhibiting NF-κB and STAT1 activation in HaCaT cells. Taken together, our findings show that OJEE reduced the risk of AD-like skin symptoms by decreasing TARC expression via inhibiting NF-κB and STAT1 activation in skin keratinocytes and thus shows promise as an alternative therapy for AD-like skin lesions.