Serum proteomics in newborns reveals a multi-pathway molecular panel for neonatal sepsis, encompassing pathogen sensing, leukocyte recruitment, and endothelial injury.

Abstract

Background: Neonatal sepsis is a major cause of morbidity and mortality, particularly in low- and middle-income countries such as Senegal, where incidence is 78-104 per 1,000 live births and mortality exceeds 20 per 1,000, with case fatality rates around 36%. Diagnosis is difficult due to non-specific clinical signs and lack of molecular biomarkers, highlighting the need for improved early diagnostic molecular markers that could be applied even outside of hospital settings. Objectives: Compare neonatal and adult serum proteomes to establish a reference and identify serum protein biomarkers of neonatal sepsis. Methods: Serum samples from Senegalese neonates and adults were analyzed using data-independent acquisition (DIA) proteomics on neat serum (Evosep-timsTOF HT platform). The cohort comprised 6 neonates with non-confirmed sepsis (NCS), 22 with confirmed sepsis (CS), 17 healthy newborn controls (HC), 6 unclassified and 20 healthy adults. Downstream analyses included differential protein abundance testing, unsupervised clustering, weighted gene co-expression network analysis (WGCNA), and correlation analyses with clinical parameters. Results: We identified 979+-20 proteins in newborns versus 718+-40 in adults. Newborns showed reduced immune-response proteins, a narrower dynamic range, and increased structural proteins such as collagens, consistent with immune immaturity and tissue development. Unsupervised WGCNA analysis led to a 53-protein cluster discriminated CS from NCS/HC. Some of these these dysregulated proteins identified have already been reported in independent studies using different approaches in neonatal and/or adult sepsis. Our larger panel however of identified markes maps to three major biological processes involved in sepsis: (i) pathogen sensing (LBP, CD14), and acute-phase inflammation (e.g. CRP, SAA1/2, ORM1/2); (ii) innate immune activation and leukocyte recruitment (e.g., FCGR3A, CSF1R, CD163, CD206) and final platelet exhaustion and metabolic dysregulation, (e.g., PF4, PPBP, THBS1, GP5); (iii) endothelial injury and microvascular dysfunction with tissue remodeling (e.g., ICAM1, VCAM1, VWF, SPARC) and loss of protective lipoproteins and serpins (e.g., APOA1, APOA2, APOM, SERPINA4, SERPINA5) Conclusion: This study provides a very comprehensive neonatal serum proteome characterization and identifies, for the first time, a protein panel of proteins mapped to three major processes in sepsis.