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6: Comprehensive proteomic mapping of cord blood to identify novel biomarkers and functional protein networks characteristic of early onset neonatal sepsis (EONS)

      Objective

      Comprehensive analysis of the blood proteome can provide better understanding of the fetal and neonatal response to a microbial attack. We conducted a multidimensional proteomic analysis of human cord blood to identify biomarkers and functional protein networks characteristic of EONS.

      Study Design

      We analyzed 152 premature neonates (GA: median 29 [range 23-34] wks) delivered by women with PTL or PPROM. All had clinically indicated amniocentesis to rule-out infection. Hematological criteria and clinical symptoms were used to define suspected EONS. Confirmed EONS was defined as a positive neonatal aerobic or anaerobic blood culture in the first 24 hours. In the discovery phase we used cord blood from 3 fetuses with confirmed E. coli sepsis, high cord blood IL-6, positive amniotic fluid cultures and gr. 4 histological chorioamnionitis (HCA). As reference we selected 3 premature (idiopathic PTB) fetuses with negative blood and amniotic fluid cultures, no HCA, no EONS and low cord blood IL-6. Differentially expressed proteins were identified by fluorescence 2-D differential gel electrophoresis (2D-DIGE), robotic tryptic digestion and mass spectrometry. Pathway analysis was performed using Protein ANalysis THrough Evolutionary Relationships (PANTHER) ontological classifications. In the validation phase specific targets were used to confirm differential expression.

      Results

      1) 68 proteins were at least 3-fold differentially expressed; 20 had unique human IPI accession numbers; 2) Potential protein biomarkers included apolipoproteins E and A-IV, 2-glycoprotein-1 and vitamin D-binding protein; 3) Major functional categories of the biomarker proteins included transfer/carrier (50%), protease and extracellular matrix (28%) and defense/immunity (14%).

      Conclusion

      We present the first evidence that EONS is characterized by differentially expressed proteins with a variety of functions. Our data sets the foundation for identification of novel diagnostic biomarkers and a better understanding of the fetal and neonatal response to infection.