Anti-inflammatory and immune response regulation of Si-Ni-San in 2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin dysfunction

Ethnopharmacological relevance: Si-Ni-San (SNS) is a well-known decoction in traditional Chinese medicine. Although studies have indicated that the anti-inflammatory and anti-allergic properties of SNS and its components can account for their therapeutic effects, the role and mechanism of SNS in treating skin dysfunction remain unclear. Aim of the study: Atopic dermatitis (AD), a disorder known for its prevalence in infants and adults, severely influences the quality of life of affected patients. In this study, we aimed to investigate the anti-inflammatory and immune response modulations of SNS in 2,4-dinitrochlorobenzene (DNCB)-induced AD-like skin dysfunction. Materials and methods: Dermatitis was induced in Kunming mice by the topical application of DNCB. SNS or dexamethasone (positive control) was topically applied every day over the course of the 21-day study. The following were assessed: dermatitis severity scores; ear and dorsal skin haematoxylin and eosin staining; interleukin (IL) - alpha, IL-beta, IL-2, IL-4, IL-6, and tumour necrosis factor (TNF)-alpha cytokine levels in the serum; spleen index; spleen CD4 + /CD8 + T lymphocyte ratio; and phosphorylation levels of mitogen-activated protein kinases (MAPKs- p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK)), IKB-alpha, and nuclear factor (NF)-kappa B (p65) in skin lesions. Results: SNS significantly alleviated the symptoms of AD-like lesions induced by DNCB, decreased the infiltration of inflammatory cells in the ear and dorsal tissues, suppressed the increased cytokine levels in the serum, reduced the CD4 + /CD8 +T lymphocyte ratio in the spleen, and downregulated the activation of MAPKs, and NF-kappa B (p65) in the dorsal skin. The effects were similar to those of dexamethasone. Conclusions: SNS alleviated the DNCB-induced AD-like skin dysfunction in mice through anti-inflammatory and immune system modulation, indicating that SNS shows potential for AD treatment in clinical settings.