Proteomics advancements in fetomaternal medicine

[Impairment of production and posttranslational changes of placental nuclear and membrane proteins with complicated pregnancy]

The content of nuclear and membrane proteins of the placenta, as well as posttranslational modification of these proteins in physiological pregnancy and placental insufficiency (PI) were studied. Differential centrifugation, electrophoresis in polyacrylamide gel, spectrophotometric methods were used. It was found that with PN there is a decrease in the degree of production of the studied proteins of varying degrees relative to control parameters. For chromatin proteins, a more pronounced decrease in the content of non-histone proteins was found in comparison with histones. Among histone fractions, the maximum decrease was detected in the H2A fraction. The degree of change in the amount of membrane proteins depends on the detergent used. Changes in posttranslational protein modifications disorders are characterized by a decrease in the content of amine and amide (especially difficult to hydrolyze) groups and an increase in carbonyl derivatives of proteins. The revealed changes in the composition and structure of the nuclear and membrane proteins of the placenta, performing numerous regulatory functions, can be triggering links in the chain of molecular damage in the placenta at PI.

Proteomics Method to Identification of Protein Profiles in Exosomes

Exosomes are membrane-bound nanovesicles that transport molecular signals (e.g., proteins) between cells and are released from a wide range of cells, including the human placenta. Interestingly, the levels of exosomes present in maternal circulation are higher in preeclamptic pregnancies and their protein content profile change in response to the microenvironment milieu. Through the discovery of candidate biomarkers, mass spectrometry (MS)-based proteomics may provide a better understanding of the pathophysiology underlying pregnancy-associated disorders. With advances in sample preparation techniques, computational methodologies, and bioinformatics, MS-based proteomics have addressed the challenge of identifying and quantifying thousands of proteins and peptides from a variety of complex biological samples. Despite increasing interest in biomarker diagnostics, the complex nature of biological matrices (e.g., plasma) poses a challenge for candidate biomarker discovery. Here we describe a workflow to prepare exosomes for proteomic analysis.

Proteomic Profiling of the Blood Serum for Prediction of Premature Delivery

Mass-spectrometric profiling of the serum in women at weeks 16-17 of gestation was carried out in order to detect proteomic predictors of preterm delivery. Changes in the production of 25 proteins (down-regulation for 13 proteins and up-regulation for 12 proteins) were detected in the sera of women whose pregnancies eventuated in premature deliveries. Among them, proteins with various regulatory functions were distinguished: antioxidant enzymes, chaperons, cytoskeleton proteins, cell adhesion molecules, and proteins involved in angiogenesis, proteolysis, transcription, inflammation processes, binding and transportation of various ligands. These results indicated the formation of proteomic imbalance as early as during trimester II, this eventually leading to premature delivery. The detected serum proteins were suggested as markers for early prediction of premature delivery.

Alterations to the maternal circulating proteome after preeclampsia

OBJECTIVE

The long-term maternal cardiovascular and metabolic implications associated with preeclampsia (PE) include risk of hypertension, heart disease, and metabolic syndrome. The objective of this study was to investigate if a recent history of PE was associated with detectable alterations in the circulating maternal proteome.

STUDY DESIGN

Six-month postpartum plasma from women with a history of PE (n = 12) and women with uncomplicated obstetrical history (n = 12) were used for analysis. Depleted maternal plasma was analyzed by label-free liquid chromatography-mass spectrometry assay. Identified peptides were searched against the International Protein Index human database version 3.87. Exponentially modified protein abundance indices were used for comparison. Results were analyzed using pathway analysis software.

RESULTS

A total of 126 eligible peptides were identified for analysis; 3 peptides were differentially expressed in the PE proteome, and an additional 5 peptides were unique to control subjects and 7 to PE subjects. PE peptide profiles were more strongly associated with markers of coagulation and complement activation compared to controls and mapped more significantly to cardiovascular disease (CVD) functions. Stratification of subjects by low (<39%) and high (≥39%) lifetime risk of CVD rather than by diagnosis produced similar findings. Comparison of controls (n = 6) to PE subjects (n = 6) without traditional cardiovascular risk factors found that while similar for body mass indices, blood pressure, and fasting lipid profiles at 6 months postpartum, PE peptide profiles continued to display stronger associations for coagulation and CVD functions. Global network analysis found that unique peptides to low-risk PE subjects were associated with cardiac infarction, CVD, and organismal injury and abnormalities.

CONCLUSION

Markers of CVD risk and progression are evident in the maternal circulating proteome 6 months postpartum after PE. Augmentations in circulating peptide profiles occur in patients with previous PE who otherwise do not have clinically measurable cardiovascular risk factors. Our data highlight the need for the implementation of postpartum prevention programs in the PE population and identifies molecules that may be targeted for screening or therapeutic benefit.

Screening and identification of potential predictive biomarkers for Down's syndrome from second trimester maternal serum

OBJECTIVE

In this study, we aimed to search for noninvasive predictive biomarkers for prenatal diagnosis of Down's syndrome (DS).

METHODS

Maternal serum samples from five DS-affected pregnant women and five DS-unaffected women were analyzed by 2D gel electrophoresis and MALDI-TOF mass spectrometry to screen for potential predictive biomarkers of DS. Then, differential levels of dGTPase, β2-glycoprotein I (β2-GPI), complement factor H-related protein 1 precursor (CFHR1) and kininogen 1 isoform 2 were further verified by western blotting tests in another independent group.

RESULTS

Statistical analysis results revealed 29 protein spots whose levels differed significantly in the DS-affected pregnancies group. Of these, the eight most differentially expressed in DP were identified successfully. Among these, levels of dGTPase, CFHR1 and kininogen 1 were elevated significantly, whereas β2-GPI was reduced in DP.

DISCUSSION

These preliminarily verified proteins might serve as potential predictive biomarkers for DS-affected pregnancies.