Batryticatus bombyx improved atopic dermatitis in NC/Nga mice and impact on inflammation and recovery of skin barrier via STAT1/P38/NF-κB downregulation and HO-1/Nrf2 activation in HaCaT keratinocytes

Batryticatus bombyx (BB) (Beauveria bassiana Vuill.) is used as an herbal medicine and food additive. Although BB has neuroprotective and anti-apoptotic effects, its impacts on atopic dermatitis (AD) are unknown. We evaluated the effects of BB in an NC/Nga mouse model of house dust mite (HDM)-induced AD, in TNF-α and IFN-γ (TI)-stimulated HaCaT keratinocytes, and in a 3D human skin model. NC/Nga mice were induced with HDM and treated with BB for 6 weeks. We assessed skin symptoms, serum levels of IgE, histamine, and IL-6, immune cell counts, and performed histological analysis of dorsal skin tissue. Additionally, we induced inflammation in HaCaT cells and a 3D human skin model using TNF-α/IFN-γ. We measured inflammatory cytokine levels, skin hydration factors, and delved into underlying mechanisms via ELISA, real-time PCR, and Western blot. BB improved skin lesions, reduced thickness, and inflammatory cell infiltration in HDM-induced mice. It alleviated scratching, improved moisture retention, and reduced IgE, histamine, and IL-6 levels. In HaCaT cells, BB inhibited thymic stromal lymphopoietin and increased hyaluronan content. It also upregulated aquaporin-3, hyaluronan synthase-1/3, filaggrin, involucrin, and occludin, enhancing skin hydration and tight junction stability. BB decreased STAT1, p38 MAPK, and NF-κB p65 levels in HaCaT cells and exhibited antioxidant effects by increasing HO-1/Nrf2 expression. BB may serve as a therapeutic alternative for AD treatment by inhibiting skin inflammation.