Intestinal iron enrichment promotes pathogenic Escherichia coli-induced ferroptosis and pyroptosis in human intestinal epithelial cells

Iron is the most abundant trace element in the human body, and both deficiency and overload can adversely impact health. Escherichia coli (E. coli), a widespread foodborne pathogen found in food and animal environments, poses a significant public health risk and is a leading cause of infectious diarrhea. While most E. coli strains exhibit low virulence, those carrying high-pathogenicity islands (HPI) display increased pathogenicity. In this study, we isolated E. coli strains containing HPI and utilized CRISPR-Cas9 technology to delete the ybtA gene, inactivating the HPI and reducing pathogenicity. We further explored the mechanisms by which this pathogen damages human intestinal epithelial cells. Tandem Mass Tag (TMT) proteomics and metabolomics analyses revealed that the PI3K-AKT pathway plays a critical role in E. coli infection, generating inflammatory mediators, primary metabolites of arachidonic acid (ARA), which are linked to the presence of HPI. Additionally, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis showed a significant rise in iron ion levels in the intestines of infected mice. To further investigate this mechanism, we supplemented cultured human intestinal epithelial cells with FeSO4. Subsequent proteomic and metabolomic analyses demonstrated that FeSO4 supplementation further increased the virulence of HPI-rich E. coli, leading to intracellular iron overload. This overload-induced oxidative stress and lipid peroxidation, ultimately causing ferroptosis in the intestinal epithelial cells. Moreover, iron enhanced the NLRP3 pyroptosis pathway induced by E. coli, mainly by promoting the assembly of the NLRP3 inflammasome and the release of GSDMD-N, which facilitated further pyroptosis in the intestinal epithelial cells. In conclusion, our findings show that foodborne E. coli infection induces intestinal iron overload, which, with the aid of iron, enhances the pathogen's virulence, leading to ferroptosis and pyroptosis in intestinal epithelial cells. This process triggers an inflammatory cytokine storm, resulting in significant intestinal damage.