Topical application of Artemisia annua L. essential oil ameliorates 2,4-dintrochlorobenzene-induced atopic dermatitis in mice

Abstract

Ethnopharmacological relevance: Volatile oil is widely used in traditional Chinese medicine owing to its unique hydrophobic and lipophilic properties and rapid skin absorption. Artemisia annua L. (A.annua) essential oil (AAEO), a volatile oil extracted from A. annua, exhibits anti-inflammatory properties. However, few studies have investigated its effects on skin inflammation.

Aim of the study: To investigate and elucidate the mechanisms of action of AAEO in the treatment of atopic dermatitis (AD).

Materials and methods: Network pharmacology was used to predict the targets and pathways of AAEO for the treatment of AD. The AD mouse model was established by topical application of 2,4-dintrochlorobenzene (DNCB), AAEO, and the positive control drug hydrocortisone butyrate cream (HBC). We evaluated the symptoms of AD, SCORAD scores, histological analysis, and serum IgE and TNF-α levels in mice. Immunofluorescence, western blotting, and qPCR were used to investigate the signaling pathways.

Results: Network pharmacology analysis indicated that AAEO may exert its effects via the MAPK/NF-κB signaling pathway. Animal experiments demonstrated that topical application of AAEO and HBC significantly ameliorated skin lesions, reduced dermatitis score, and decreased spleen weight compared to DNCB treatment. AAEO reduced skin epidermal thickness and mast cell infiltration. DNCB markedly reduced the protein levels of filaggrin (FLG) and loricrin (LOR), whereas AAEO reversed these changes. Notably, the 5% concentration of AAEO demonstrated substantial improvement in skin barrier function. Compared to the DNCB group, the levels of FLG and LOR remained almost unchanged following HBC treatment. DNCB markedly elevated IgE and TNF-α levels, which were reversed by AAEO and HBC treatment. Among the inflammatory cytokines, DNCB increased mRNA expression of TNF-α, IL-1β, and IL-6, however, it reduced IL-10, with AAEO and HBC reversing these changes to various degrees. Additionally, DNCB-induced ERK, JNK, and P38 phosphorylation, associated with the upregulation of phosphorylation of NF-κB, whereas, AAEO and HBC exhibited potent inhibition of the MAPK/NF-κB signaling pathway.

Conclusions: This study systematically demonstrated the possible therapeutic effects and mechanisms of AAEO in AD via network pharmacological analysis and experimental confirmation. These results revealed that topical application of AAEO can suppress skin inflammation and restore skin barrier function. These findings provide the potential application of AAEO in synthesizing external preparations for both pharmacological and cosmetic industries.

Keywords: A.annua essential oil; Atopic dermatitis; Inflammation; Skin barrier function.