Preeclampsia is a dangerous complication in pregnancy and is potentially life-threatening for both mother and baby. Researchers such as Kim et al. are trying to reduce preeclampsia complications by establishing earlier diagnostics based on blood biomarkers.1 The team used a global proteomics strategy to look for PE candidate biomarkers in three pairs of plasma samples obtained from pregnant women in the early second trimester.
The researchers analyzed stored plasma from women in weeks 16–21 of pregnancy. Of those samples, 13 samples came from patients who later developed preeclampsia. The researchers also analyzed 13 samples from healthy patients as matched controls. The two groups had no significant differences based on age, parity, gestational age at blood sampling or body mass index.
The researchers immunodepleted six highly abundant proteins in the samples and then measured protein concentration using a BCA protein assay kit (Thermo Scientific). They used sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to separate the proteins. They then fractionated samples into 10 gel band regions and performed an in-gel trypsin digest.
The team used a duplicated mass liquid chromatography and tandem mass spectrometry (LC-MS/MS) analysis using an LTQ Velos mass spectrometer interfaced with a nano high-performance LC system (both Thermo Scientific) and an Agilent 6490 triple quadrupole mass spectrometer to analyze peptides. For even broader coverage, they also performed a multiplexed multiple reaction monitoring MS analysis.
The team found 168 differentially expressed proteins (DEPs), including 72 that were upregulated (three upregulated in all three paired samples, 18 upregulated in two paired samples and 51 upregulated in only one paired sample). They also found 96 downregulated proteins (11 downregulated in all three paired samples, 29 downregulated in two paired samples and 56 downregulated in only one paired sample). A functional analysis revealed proteins involved in cell-to-cell signaling and interaction (56 DEPs), cellular movement (55 DEPs), protein synthesis (39 DEPs) and degradation (28 DEPs). On the whole, inflammatory and immune responses were most common.
Kim et al. found increased expression levels of complement components, namely complement C1s and subcomponent C1S. They also saw increased alpha-1-microglobulin/bikunin precursor (protein AMBP) in preeclampsia patients before the manifestation of clinical disease. The authors posit that these proteins may be involved in the remodeling process of the spiral arteries even before PE manifestation, and may help predict an increased risk of developing PE.
1. Kim, S.M., et al. (2016) “Expression changes of proteins associated with the development of preeclampsia in maternal plasma: A case-control study,” Proteomics, 16(10) (pp. 1581–1589), doi: 10.1002/pmic.201500381.