PYR-41, an inhibitor of ubiquitin-activating enzyme E1, attenuates 2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions in mice.

PYR-41 is an irreversible and cell permeable inhibitor of ubiquitin-activating enzyme E1, and has been reported to inhibit the degradation of IκB protein. Previous studies have shown that PYR-41 has effects on anti-inflammatory, but whether it has therapeutic effects on allergic dermatitis is unclear. The aim of this research was to explore the therapeutic effects of PYR-41 on atopic dermatitis. The effects of PYR-41 on the activation of NF-κB signaling pathway and the expression of inflammatory genes in HaCat cells were tested by western blot and qPCR. A mouse model was built, and the AD-like skin lesions were induced by 2,4-dinitrochlorobenzene (DNCB). Then, the treatment effects of PYR-41 were examined by skin severity score, ear swelling, ELISA, and qPCR. The results showed that PYR-41 can significantly reduce the K63-linked ubiquitination level of nuclear factor-κB essential modulator (NEMO) and tumor necrosis factor receptor associated factor 6 (TRAF6), inhibit the proteasomal degradation of IκBα, thereby activate TNF-α-induced NF-κB signaling pathway in HaCat cells. In addition, DNCB-treated mice have significant reduction in symptoms after treated by PYR-41, including reduced ear thickening and reduced skin damage. Serum tests showed that PYR-41 significantly reduced the expression of IgE, IFN-γ, and TNF-α. In conclusion, the current results suggest that PYR-41 has potential to reduce the symptoms of atopic dermatitis.