Urinary proteomics identifies unique signatures in infants with congenital diaphragmatic hernia and tetralogy of Fallot

BACKGROUND: Serum biomarkers of right ventricular (RV) fibrosis associate with adverse outcomes in right heart conditions. Urinary protein profiling may be preferable in critically ill infants, but its feasibility is unknown. We sought to characterize the urinary proteome in conditions affecting the RV-Tetralogy of Fallot (TOF) and congenital diaphragmatic hernia (CDH)-and to explore the impact of surgery. METHODS: Urine from 53 infants (19 CDH, 17 TOF, 17 controls) was analyzed in this prospective single-center pilot study. Protein detection and quantification were performed by mass spectrometry with data-independent acquisition. Groups were compared via Voom/Limma in R, and significantly different proteins were surveyed for pathway enrichment. RESULTS: Pre-operatively, both CDH and TOF samples clustered away from controls. Post-operatively, TOF normalized towards controls, whereas CDH remained segregated. In CDH, proteins that differed significantly from controls and changed with surgery were clustered into cell-cell adhesion/junction, complement activation, and immune regulation. In TOF, post-operatively upregulated proteins were critical to prostanoid/prostaglandin metabolism, purine metabolism, and glutathione metabolism/oxidative stress, while post-operatively normalized proteins were critical to extracellular matrix organization and platelet regulation. CONCLUSIONS: RV pathologies demonstrate distinct urinary proteomic signatures. Future studies should investigate associations between urinary biomarkers, RV function, and clinical outcomes. IMPACT: Serum biomarkers of right ventricular (RV) fibrosis associate with adverse outcomes in tetralogy of Fallot (TOF), but data are limited in other RV pathologies including congenital diaphragmatic hernia (CDH). Urinary proteomics may be preferable to blood sampling in critically ill infants, but the feasibility is unknown. We demonstrated that urinary proteins in TOF and CDH differ from healthy controls. TOF proteins broadly normalize post-operatively, while the abnormal CDH proteome persists, indicating that surgery does not modify the underlying physiology in CDH. These data provide a foundation to study associations between urinary proteomics and RV function.