Inhibitory effect of ethanol extract of Ampelopsis brevipedunculata rhizomes on atopic dermatitis-like skin inflammation

Ethnopharmacological relevance: Extracts from various parts of Ampelopsis brevipedunculata has been used as anti-inflammatory agents in Asian folk medicine. Aim of the study: To demonstrate the medicinal effect of the A. brevipedunculata in skin inflammation, specifically atopic dermatitis (AD). Materials and methods: The effect of ethanol extract of A. brevipedunculata rhizomes (ABE) on AD was examined using an AD-like skin inflammation model induced by repeated exposure to house dust mite (Dermatophagoides farinae extract, DFE) and 2,4-dinitrochlorobenzene (DNCB). The mechanism study was performed using tumor necrosis factor (TNF)-α and interferon (IFN)-γ-activated human keratinocytes (HaCaT). Serum histamine and immunoglobulin levels were quantified using enzymatic kits, while the gene expression of cytokines and chemokines was analyzed using quantitative real time polymerase chain reaction. The expression of signaling molecules was detected using Western blot. Results: Oral administration of ABE alleviated DFE/DNCB-induced ear thickening and clinical symptoms, as well as immune cell infiltration (mast cells and eosinophils) into the dermal layer. Serum Immunoglobulin (Ig) E, DFE-specific IgE, IgG2a, and histamine levels were decreased after the administration of ABE. ABE also inhibited CD4 ⁺ IFN-γ ⁺ and CD4 ⁺ IL-4 ⁺ lymphocyte polarization in lymph nodes and expression of TNF-α, IFN-γ, IL-4, IL-13, and IL-31 in the ear tissue. In TNF-α/INF-γ-stimulated keratinocytes, ABE inhibited the gene expression of TNF-α, IL-6, IL-1β, and CCL17. In addition, ABE decreased the nuclear localization of signal transducer and activator of transcription 1 and nuclear factor-κB, and the phosphorylation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase. Conclusion: Collectively, our data demonstrate the pharmacological role and signaling mechanism of ABE in the regulation of skin allergic inflammation, which supports our suggestion that ABE could be developed as a potential therapeutic agent for the treatment of AD.