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Ethnopharmacological relevance Huang-Lian-Jie-Du Decoction (HLJDD), is a well-known traditional Chinese herbal formula first written in the Tang dynasty. In Chinese medicine practice, HLJDD is commonly prescribed to treat various inflammatory skin diseases, such as atopic dermatitis (AD) and psoriasis. Aim of the study The present study aimed at investigating the therapeutic effect of HLJDD extract (HLJDE) and to elucidate the underlying molecular mechanisms of action in the 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD-like mice. Materials and methods Female Balb/c mice were sensitized with DNCB for three days. After sensitization, mice were challenged with DNCB every three days and orally administrated with HLJDE (150, 300 and 600 mg/kg) daily from day 14 to day 29 for consecutive 16 days. At the end of experiment, the clinical AD scores of the mice were calculated to evaluate the therapeutic effect of HLJDE, and serum, ears and dorsal skin of the mice were collected for unravelling molecular mechanisms. Results HLJDE significantly reduced the clinical symptoms in the AD-like mice by inhibiting eosinophil and mast cell infiltration, suppressing the production of Th2-associated cytokine (IL-4) and pro-inflammatory cytokines (TNF-α). In addition, HLJDE significantly suppressed the NF-κB and MAPKs pathways. Moreover, HLJDE was able to accentuate filaggrin expression in the skin lesion when compared to the sensitized mouse without treatment. Conclusion HLJDE significantly improved the AD-like symptoms on the DNCB-sensitized mice through mitigating the production of inflammatory mediators via suppressing MAPKs and NF-κB pathways. Additionally, the elevated expression of filaggrin in the skin lesion by HLJDE contributes to the recovery of dysfunctional skin barrier on the DNCB-sensitized mice.

Ethnopharmacological relevance Huang-Lian-Jie-Du Decoction (HLJDD), a well-known Chinese herbal formula recorded in the Tang dynasty, is composed of Coptidis rhizoma (Huang-Lian), Scutellariae radix (Huang-Qin), Phellodendri Chinensis cortex (Huang-Bai) and Gardenia fructus (Zhi-Zi). It has clinical efficacy of purging fire for removing toxin and is commonly used for the treatment of disease including Alzheimer's disease, stroke and gastrointestinal disorders. HLJDD is also frequently applied for the treatment of various skin diseases, such as atopic dermatitis (AD) and various types of eczema. The aim of this study is to investigate the anti-inflammatory and anti-allergic actions of Huang-Lian-Jie-Du ethanolic extract (HLJDE) and to elucidate underlying molecular mechanisms of action using relevant in vitro experimental models. Materials and methods The anti-inflammatory effects of HLJDE were investigated through evaluating the change of nitric oxide (NO) and the production of several cytokines and chemokines in lipopolysaccharide (LPS)-stimulated RAW264.7 cell line. Expression of mitogen-activated protein kinases (MAPKs), NF-κB p65 phosphorylation, inhibitor-κBα (IκBα) degradation were further investigated to elucidate its anti-inflammatory molecular mechanisms. Meanwhile, the anti-allergic activities of HLJDE was also evaluated using antigen-induced RBL-2H3 cell line. β-hexosaminidase and histamine release and selected cytokines and chemokines were measured to evaluate the anti-allergic activities of HLJDE. In addition, intracellular Ca2+level, MAPKs and Lyn phosphorylation were further investigated to reveal its anti-allergic molecular mechanisms. Results HLJDE could significantly suppress the secretion of NO, IL-1β, IL-4, MCP-1 and GM-CSF in RAW264.7 cells in a dose-dependent manner. In addition, HLJDE also markedly reduced the phosphorylation of MAPKs, and inhibited the transcriptional activity of NF-κB and IκBα degradation. Furthermore, HLJDE exerted marked anti-allergic activity through inhibiting the release of β-hexosaminidase and histamine. The release of cytokines and chemokines (IL-4, TNF-α, MCP-1) from activated RBL-2H3 cells were also attenuated by pretreatment with HLJDE. The inhibitory effects on intracellular Ca2+level, and reduced phosphorylation of MAPKs and Lyn are believed to be the anti-allergic mechanisms. Conclusions HLJDE exerted significant anti-inflammatory and anti-allergic effects through suppressing the production of allergic and inflammatory mediators via the NF-κB and MAPKs inactivation and IκBα degradation in the LPS-stimulated RAW24.7 cells, inactivation of MAPKs and Lyn pathway in antigen-induced RBL-2H3 cells. The present study provides in vitro experimental evidence to support the use of HLJDE for the clinical treatment of AD.