A novel biomimetic nanozyme orchestrates ulcerative colitis resolution by targeting KEAP1-NRF2-ARE pathway: Redox balance restoration, colonic barrier repair, immune homeostasis regulation.

Ulcerative colitis (UC) leads to systemic complications with excessive oxidative stress, colonic barrier damage, and inflammation. Deuterohemin-AlaHisThrValGluLys (DhHP-6) is the biomimetic nanozyme rationally designed to mimic the peroxidase activity of Microperoxidase-11. It exhibits potent antioxidant properties, which might emerge as a promising therapeutic candidate compound for UC. In this paper, we aimed to probe the therapeutic effects of DhHP-6 on UC and clarify the underlying molecular mechanisms. We employed dextran sulfate sodium-induced C57BL/6 J male mice for in vivo studies. Lipopolysaccharides-induced intestinal epithelial (Caco-2) and macrophage (RAW264.7) cells were established for in vitro studies. Immunofluorescence, reactive oxygen species (ROS) assays were utilized to evaluate the therapeutic effects on UC. Mitochondrial function assessment, Western blotting analysis, luciferase reporter assays, and AlphaFold 3 studies, the mechanism by which DhHP-6 affected UC via NRF2 was explored. DhHP-6 ameliorated UC by eliminating ROS to protect the colonic barrier and immune homeostasis. It upregulated NRF2 expression, validated by the enhanced NRF2/ARE luciferase activity (p < 0.001) and NRF2 immunofluorescence. AlphaFold 3 analysis revealed the stable binding of DhHP-6 to the KEAP1 Kelch domain, which might interfere with the KEAP1-NRF2 interaction. The activation of NRF2 restored mitochondrial function, inhibited apoptosis, and attenuated inflammation. In summary, DhHP-6 exerted multi-dimensional therapeutic effects on UC, which were underpinned by the activation of the KEAP1-NRF2-ARE pathway as demonstrated through in vivo, in vitro, and in silico analyses. Therefore, DhHP-6 might be a highly promising candidate compound for the management of UC.