Plasma-activated solutions alleviate intestinal mucosal injury induced by pathogen-host interactions by modulating redox imbalance.

BACKGROUND

SARS-CoV-2 spike binds angiotensin-converting enzyme 2 (ACE2), but the mechanisms linking spike exposure to intestinal injury remain incompletely understood. We investigated whether plasma-activated solutions (PAS) alleviate spike-associated intestinal injury by regulating antioxidant signaling.

METHODS

Intestinal injury was induced by recombinant spike receptor-binding domain exposure in humanized ACE2 mice pretreated with dextran sulfate sodium. Caco-2 and HCT116 cells were used for in vitro experiments. PAS was administered orally to mice or applied as plasma-activated culture medium to cells. Reactive oxygen species (ROS) levels, apoptosis, and tissue injury were assessed. Protein stability assays, co-immunoprecipitation, and pathway interventions were used to investigate the underlying mechanism.

RESULTS

Spike exposure increased oxidative stress and epithelial apoptosis and enhanced the association between Kelch-like ECH-associated protein 1 (KEAP1) and nuclear factor erythroid 2-related factor 2 (NRF2), accompanied by increased NRF2 ubiquitination, reduced NRF2 stability, and lower heme oxygenase-1 (HO-1) expression. PAS alleviated intestinal injury, reduced ROS accumulation and apoptosis, decreased KEAP1-NRF2 association, and increased NRF2 nuclear accumulation. NRF2 knockdown or pharmacological inhibition of HO-1 attenuated the protective effects of PAS.

CONCLUSION

PAS alleviates spike-associated intestinal injury in the experimental models examined, with the findings supporting a contribution of KEAP1-NRF2/HO-1 signaling to its protective effects.