| Purpose:Neonatal neutrophils are characterized by the immaturity of bactericidal mechanisms which contributes largely to neonates mortality. Although the immaturity in neonatal neutrophils function has been well described, there remains no unifying theory to explain the various alterations in function. In this study, we performed an iTRAQ-based quantitative proteomic analysis of two groups of clinical samples to seek for mechanisms underlying for immaturity of bactericidal.Methods:iTRAQ-based quantitative proteomic analysis of two groups of clinical samples, which are the neonatal neutrophils derived from human cord-blood and the adult neutrophils, respectively. KEGG pathway to analyze the differentiated expressed proteins function. Western blot was for certifying the iTRAQ result.Results:A total of1332proteins were identified,98%of which were quantified. Among them,127proteins were characterized to be differentially expressed between adult and cord neutrophils using a cutoff fold change value great than1.24(p<0.05).103down-regulated proteins and24up-regulated proteins were classified by KEGG into4and1pathways with at least3members in each pathway separately (p<0.05). Remarkably, three out of four pathways, proteasome, leukocyte transendothelial migration and glyoxylate and dicarboxylate metabolism from down-regulated proteins and phagosome from up-regulated proteins are immune-related, indicating the major functional difference between cord neutrophils and adult neutrophils is their immune response. In particular, many proteins associated with NETs pathway, a critical mechanism for antimicrobial process and auto-clearance, were also found to be down-regulated in cord neutrophils. Conclusion:We report a first comparative characterization of the global proteomes of primary cord and adult neutrophils. We identified many differentially expressed proteins and pathways that are consistent with the observed functional difference between neonatal and adult neutrophils in terms of response to stimuli, cell motility and phagocytosis. We also found that many NETs components in cord neutrophils were down-regulated as compared to adult neutrophils, which probably contribute to the delay of NETs formation in cord neutrophils. This global comparative proteomic study not only provides an overall knowledge of proteins from both cord and adult neutrophils in this field, but also suggests a clue for us to understand the neonatal neutrophils function deficiency and to further study the function of neonatal neutrophils in the future. |
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