Deer antler peptides attenuate inflammation, oxidative stress, and pyroptosis in Salmonella-infected macrophages and murine colonic tissues

OBJECTIVE: Deer antler peptides (DAPs) are well documented for their potent anti-inflammatory and antioxidant properties, although their efficacy in alleviating pathogen-induced intestinal infections mechanisms remain poorly understood. In this study, we investigated the protective effects of DAPs against Salmonella-induced intestinal inflammation and associated tissue injury, while elucidating the molecular mechanisms involved. METHODS: Primary peritoneal macrophages isolated from wild-type (WT) and NRF2 knockout (nrf2-/-) mice were infected with Salmonella; concurrently, we established a murine model of Salmonella-induced intestinal inflammation by infecting WT and nrf2-/- mice. Using both in vitro and in vivo systems, we evaluated the immunomodulatory effects of DAPs during Salmonella infection. RESULTS: In vitro, the results demonstrated that DAPs significantly inhibited the Salmonella- induced production of TNF-α and IL-6, the activation of MAPK signaling pathway, GSDMD- mediated pyroptosis, and excessive reactive oxygen species accumulation. Mechanistically, DAPs activate the NRF2 signaling pathway by promoting nuclear translocation and the transcriptional upregulation of HO-1 and NQO-1. The genetic deletion of NRF2 substantially attenuated the protective effects of DAPs against inflammation, pyroptosis, and oxidative stress, thus confirming the dependence of this mechanism on this pathway. In vivo, DAPs significantly reduced intestinal histopathological changes, epithelial barrier disruption, pyroptosis, and oxidative damage in WT mice, however these protective effects were markedly diminished in nrf2-/- mice. Notably, DAPs significantly reduced colonic bacterial loads in both WT and nrf2-/- mice while concurrently suppressing pyroptosis. Our findings indicate that DAPs may exert antibacterial effects through a mechanism independent of both NRF2 activation and the NLRP3-mediated pyroptotic pathway; however, the underlying molecular mechanism remains to be fully elucidated. CONCLUSION: Our findings reveal DAPs function as multi-modal regulators that coordinately suppress inflammation, pyroptosis, and oxidative stress through NRF2 activation during Salmonella infection, and provides mechanistic insights and a translational basis for the application of animal-derived peptides in the treatment of infectious intestinal disorders.