Quantitative protein analysis and glycan profiling of umbilical cord plasma and corresponding maternal plasma samples

Protein glycosylation is an essential post-translational modification boosting proteomic diversity. The major groups of human plasma glycoproteins are immunoglobulins (Igs) and acute-phase proteins (APPs). Changes in plasma Ig and APP levels and their glycosylation have been previously associated with inflammatory diseases, several types of cancer, pregnancy, or aging. In this study, we present a novel approach to investigate the neonatal and maternal plasma at the end of pregnancy using a combination of targeted quantitative proteomics and total plasma N-glycome profiling. We present a new SRM-based multiplex assay to quantify 19 APPs and 7 Igs. We applied this assay to 98 samples of umbilical cord plasma and corresponding maternal plasma samples and observed significantly lower levels of all analyzed proteins in neonates, apart from the glycoprotein alpha-2-macroglobulin. Unlike previous methods, our SRM-MS assay allows us to quantify dozens of proteins simultaneously and to distinguish protein variants. We compared maternal and fetal total plasma-released N-glycomes in the same set of samples. We quantified 66 individual glycans, which were used to calculate 73 glycosylation traits. In neonates, the major N-glycans were di-antennary complex-type with core fucosylation, and the production of higher, branched, sialylated N-glycans was limited.