Integrated untargeted and targeted metabolomics combined with experimental validation reveal glutathione-related oxidative stress in pediatric IgA vasculitis nephritis.

Objective: IgA vasculitis nephritis (IgAVN) is the principal cause of morbidity and mortality in children with IgA vasculitis (IgAV),the pathogenesis of the renal injury and predictive biomarkers are still unclear. In this study, we performed an integrated untargeted and targeted metabolomics to identify candidate biomarkers and explore oxidative stress-related alterations associated with IgAVN. Methods: Serum samples were collected from 115 IgAV and 111 IgAVN children. We conducted untargeted metabolomics for preliminary screening of potential biomarkers on 50 IgAV and 50 IgAVN children and then performed validation experiments based on targeted LC-MS/MS on 65 IgAV and 61 IgAVN children. In addition, an IgAVN animal model was established to preliminarily verify oxidative stress-related alterations associated with key metabolic abnormalities by assessing the levels of GSH, GSH/GSSG, MDA, 4-HNE, NRF2, HO-1, and GPX4. Results: A total of 45 differential metabolites were identified between the IgAV and IgAVN groups, including 23 upregulated and 22 downregulated metabolites, which were mainly enriched in glutathione metabolism, pyruvate metabolism, the citrate cycle, sphingolipid metabolism, and steroid hormone biosynthesis. Further targeted validation confirmed that six metabolites, including sphinganine, dehydroepiandrosterone, kynurenine, glutathione, nervonic acid, and creatine differed significantly between the two groups. The combined model based on these six metabolites showed good discriminatory performance, with an AUC of 0.903 and an area under the PRC curve of 0.909. In the animal experiments, the model group exhibited decreased GSH levels, a disrupted GSH/GSSG balance, increased MDA and 4-HNE levels, as well as abnormal expression of NRF2, HO-1, and GPX4. Conclusion: Children with IgAVN exhibit a distinct metabolic profile characterized by glutathione depletion, activation of inflammation-related tryptophan metabolism, lipid/membrane remodeling, and disordered energy metabolism. Sphinganine, dehydroepiandrosterone, kynurenine, glutathione, nervonic acid, and creatine may serve as potential biomarkers for IgAVN, and the combined model based on these metabolites showed good discriminatory ability and potential clinical utility. The consistency between the clinical metabolomics findings and the experimental evidence supports supports glutathione-related oxidative stress and the GSH-NRF2/HO-1/GPX4 axis as candidate pathways associated with IgAVN-related renal injury. These findings provide a basis for early risk identification and future mechanistic and pharmacological investigations in pediatric IgAVN.