Escin alleviates DNCB-induced atopic dermatitis-like symptoms by promoting autophagy activation and tight junction barrier restoration

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by impaired skin barrier function and immune dysregulation. Autophagy, a lysosome-dependent degradation pathway essential for removing unnecessary components, plays a crucial role in maintaining cellular homeostasis. Defective autophagy has been implicated in AD pathogenesis, and enhancing autophagic activity represents a viable therapeutic strategy. This study investigated the potential of the natural saponin escin to ameliorate AD through autophagy activation. We demonstrated that escin induced autophagy in HaCaT keratinocytes and mitigated tight junction (TJ) barrier disruption in an AD-like cell model stimulated with IL-4 and IL-13. Notably, silencing ATG7, an essential autophagy-related protein, abrogated the barrier-restorative effects of escin. Furthermore, in a 2,4-dinitrochlorobenzene (DNCB)-induced murine model of AD, escin treatment ameliorated AD-like skin lesions, reduced mast cell infiltration, and decreased cutaneous levels of the pro-inflammatory cytokines IL-4, IL-13, and IFN-γ. Escin administration also restored the epidermal expression of key TJ proteins, Claudin-1 and ZO-1. Mechanistically, escin promoted the nuclear translocation of transcription factor EB (TFEB) and upregulated the expression of genes involved in autophagy and lysosome biogenesis. These protective effects were associated with the activation of the AMPK-mTORC1-TFEB signaling pathway. Collectively, our findings indicate that escin enhances autophagy and restores skin barrier function, highlighting its potential as a novel therapeutic agent for AD treatment.