Dynamic urinary proteomic signatures reveal key molecular pathways and biomarkers in pediatric obstructive sleep apnea

This study aimed to determine whether paired pre-sleep and morning urinary proteomic profiling, expressed as the morning-to-bedtime protein ratio, can identify severity-associated molecular signatures and candidate biomarkers in pediatric obstructive sleep apnea (OSA). A total of 40 children were included, comprising 13 non-snoring controls and 27 children with PSG-defined OSA, including mild, moderate, and severe disease. Urine samples were collected before sleep and the following morning. Data-independent acquisition mass spectrometry was used to quantify proteins, and morning-to-bedtime ratios were calculated. Clustering, functional enrichment, protein-protein interaction network analysis, molecular docking, and single-cell RNA-seq validation were performed. Five distinct expression patterns were identified, among which Cluster 4 showed a progressive decline in morning-to-bedtime ratios with increasing OSA severity. IGFBP7, PRDX1, GSTP1, and IL6ST emerged as hub proteins associated with extracellular matrix remodeling, oxidative stress, and inflammatory signaling. Molecular docking demonstrated strong affinities between these proteins and commonly used OSA medications. Single-cell analyses revealed that the key proteins originate mainly from activated immune cell subsets, linking urinary alterations to systemic immune responses. Dynamic urinary proteomic profiling, particularly the morning-to-bedtime ratio, sensitively reflects nocturnal pathophysiological disturbances in pediatric OSA. IGFBP7, PRDX1, GSTP1, and IL6ST represent promising noninvasive biomarker candidates for disease stratification and provide hypothesis-generating molecular targets for future mechanistic and therapeutic studies.