Extracts of Grifola frondosa inhibit the MAPK signaling pathways involved in keratinocyte inflammation and ameliorate atopic dermatitis.

Background/objectives: Grifola frondosa, commonly referred to as the maitake mushroom, has been studied extensively to explore its potential health benefits. However, its anti-inflammatory effects in skin disorders have not been sufficiently elucidated. This study aimed to elucidate the anti-inflammatory role of the ethanol extract of G. frondosa in atopic dermatitis (AD) using in vivo and in vitro models.

Materials/methods: We investigated its impact on skin and spleen inflammatory responses in Dermatophagoides farinae extract (DFE)/1-chloro-2,4 dinitrochlorobenzene (DNCB)-induced AD-like skin lesions in a mouse model. Additionally, we determined the immunosuppressive response and mechanism of G. frondosa by inducing atopic-like immune reactions in keratinocytes through tumor necrosis factor (TNF)-α/interferon (IFN)-γ stimulation.

Results: Our study revealed that G. frondosa ameliorates clinical symptoms in an AD-like mouse model. These effects contributed to the suppression of Th1, Th2, Th17, and Th22 immune responses in the skin and spleen, leading to protection against cutaneous inflammation. Furthermore, G. frondosa inhibited the production of antibodies immunoglobulin (Ig)E and IgG2a in the serum of AD mice. Importantly, the inhibitory effect of G. frondosa on inflammatory cytokines in TNF-α/IFN-γ-stimulated AD-like keratinocytes was associated with the suppression of MAPK (Mitogen Activated Protein Kinase) pathway activation.

Conclusions: Collectively, these findings highlight the potential of G. frondosa as a novel therapeutic agent for AD treatment and prevention.