The relationship of circulating proteins in early pregnancy with preterm birth

Predicting Preterm Birth Using Proteomics

The complexity of preterm birth (PTB), both spontaneous and medically indicated, and its various etiologies and associated risk factors pose a significant challenge for developing tools to accurately predict risk. This review focuses on the discovery of proteomics signatures that might be useful for predicting spontaneous PTB or preeclampsia, which often results in PTB. We describe methods for proteomics analyses, proteomics biomarker candidates that have so far been identified, obstacles for discovering biomarkers that are sufficiently accurate for clinical use, and the derivation of composite signatures including clinical parameters to increase predictive power.

Preterm birth, a consequence of immune deviation mediated hyperinflammation

Preterm birth represents a multifaceted syndrome with intricacies still present in our comprehension of its etiology. In the context of a semi-allograft, the prosperity from implantation to pregnancy to delivery hinges on the establishment of a favorable maternal-fetal immune microenvironment and a successful trilogy of immune activation, immune tolerance and then immune activation transitions. The occurrence of spontaneous preterm birth could be related to abnormalities within the immune trilogy, stemming from deviation in maternal and fetal immunity. These immune deviations, characterized by insufficient immune tolerance and early immune activation, ultimately culminated in an unsustainable pregnancy. In this review, we accentuated the role of both innate and adaptive immune reason in promoting spontaneous preterm birth, reviewed the risk of preterm birth from vaginal microbiome mediated by immune changes and the potential of vaginal microbiomes and metabolites as a new predictive marker, and discuss the changes in the role of progesterone and its interaction with immune cells in a preterm birth population. Our objective was to contribute to the growing body of knowledge in the field, shedding light on the immunologic reason of spontaneous preterm birth and effective biomarkers for early prediction, providing a roadmap for forthcoming investigations.

Sequential disruptions to inflammatory and angiogenic pathways and risk of spontaneous preterm birth in Malawian women

Preterm birth is a leading cause of death in children under five years of age. We hypothesized that sequential disruptions to inflammatory and angiogenic pathways during pregnancy increase the risk of placental insufficiency and spontaneous preterm labor and delivery. We conducted a secondary analysis of inflammatory and angiogenic analytes measured in plasma samples collected across pregnancy from 1462 Malawian women. Women with concentrations of the inflammatory markers sTNFR2, CHI3L1, and IL18BP in the highest quartile before 24 weeks gestation and women with anti-angiogenic factors sEndoglin and sFlt-1/PlGF ratio in the highest quartile at 28-33 weeks gestation had an increased relative risk of preterm birth. Mediation analysis further supported a potential causal link between early inflammation, subsequent angiogenic dysregulation detrimental to placental vascular development, and earlier gestational age at delivery. Interventions designed to reduce the burden of preterm birth may need to be implemented before 24 weeks of gestation.

Proteomic analysis of plasma to identify novel biomarkers for intra-amniotic infection and/or inflammation in preterm premature rupture of membranes

To identify potential plasma biomarkers associated with microbial invasion of the amniotic cavity (MIAC) and/or intraamniotic inflammation (IAI) in women with preterm premature rupture of membranes (PPROM). This retrospective cohort study included 182 singleton pregnant women with PPROM (23-33 weeks) who underwent amniocentesis. Plasma samples; all subjects were chosen from these participants and were analyzed using label-free liquid chromatography-tandem mass spectrometry for proteome profiling using a nested case-control study design (cases with MIAC/IAI vs. non-MIAC/IAI controls [n = 9 each]). Three identified target molecules for MIAC/IAI were further verified by ELISA in the study cohort (n = 182). Shotgun proteomic analysis revealed 17 differentially expressed proteins (P < 0.05) in the plasma of MIAC/IAI cases. In particular, the levels of FCGR3A and haptoglobin, but not LRP1, were found to be increased in the plasma of patients with MIAC, IAI, and both MIAC/IAI compared with those without these conditions. Moreover, these differences remained significant after adjusting for gestational age at sampling. The area under the curves of plasma FCGR3A and haptoglobin ranged within 0.59-0.65 with respect to each of the three outcome measures. Plasma FCGR3A and haptoglobin were identified as potential independent biomarkers for less-invasively detecting MIAC/IAI in women with PPROM.

Identification of potential therapeutic intervening targets by in-silico analysis of nsSNPs in preterm birth-related genes

Prematurity is the foremost cause of death in children under 5 years of age. Genetics contributes to 25-40% of all preterm births (PTB) yet we still need to identify specific targets for intervention based on genetic pathways. This study involved the effect of region-specific non-synonymous variations and their transcript level mutational impact on protein functioning and stability by various in-silico tools. This investigation identifies potential therapeutic targets to manage the challenge of PTB, corresponding protein cavities and explores their binding interactions with intervening compounds. We searched 20 genes coding 55 PTB proteins from NCBI. Single Nucleotide Polymorphisms (SNPs) of concerned genes were extracted from ENSEMBL, and filtration of exonic variants (non-synonymous) was performed. Several in-silico downstream protein functional effect prediction tools were used to identify damaging variants. Rare coding variants were selected with an allele frequency of ≤1% in 1KGD, further supported by South Asian ALFA frequencies and GTEx gene/tissue expression database. CNN1, COL24A1, IQGAP2 and SLIT2 were identified with 7 rare pathogenic variants found in 17 transcript sequences. The functional impact analyses of rs532147352 (R>H) of CNN1 computed through PhD-SNP, PROVEAN, SNP&GO, PMut and MutPred2 algorithms showed impending deleterious effects, and the presence of this pathogenic mutation in CNN1 resulted in large decrease in protein structural stability (ΔΔG (kcal/mol). After structural protein identification, homology modelling of CNN1, which has been previously reported as a biomarker for the prediction of PTB, was performed, followed by the stereochemical quality checks of the 3D model. Blind docking approach were used to search the binding cavities and molecular interactions with progesterone, ranked with energetic estimations. Molecular interactions of CNN1 with progesterone were investigated through LigPlot 2D. Further, molecular docking experimentation of CNN1 showed the significant interactions at S102, L105, A106, K123, Y124 with five selected PTB-drugs, Allylestrenol (-7.56 kcal/mol), Hydroxyprogesterone caproate (-8.19 kcal/mol), Retosiban (-9.43 kcal/mol), Ritodrine (-7.39 kcal/mol) and Terbutaline (-6.87 kcal/mol). Calponin-1 gene and its molecular interaction analysis could serve as an intervention target for the prevention of PTB.

Cervicovaginal Complement Activation and Microbiota During Pregnancy and in Parturition

Background

Vaginal microbiome and the local innate immune defense, including the complement system, contribute to anti- and proinflammatory homeostasis during pregnancy and parturition. The relationship between commensal vaginal bacteria and complement activation during pregnancy and delivery is not known.

Objective

To study the association of the cervicovaginal microbiota composition to activation and regulation of the complement system during pregnancy and labor.

Study design

We recruited women during late pregnancy (weeks 41 + 5 to 42 + 0, n=48) and women in active labor (weeks 38 + 4 to 42 + 2, n=25). Mucosal swabs were taken from the external cervix and lateral fornix of the vagina. From the same sampling site, microbiota was analyzed with 16S RNA gene amplicon sequencing. A Western blot technique was used to detect complement C3, C4 and factor B activation and presence of complement inhibitors. For semiquantitative analysis, the bands of the electrophoresed proteins in gels were digitized on a flatbed photo scanner and staining intensities were analyzed using ImageJ/Fiji win-64 software. Patient data was collected from medical records and questionnaires.

Results

The vaginal microbiota was Lactobacillus-dominant in most of the samples (n=60), L. iners and L. crispatus being the dominant species. L. gasseri and L. jensenii were found to be more abundant during pregnancy than active labor. L. jensenii abundance correlated with C4 activation during pregnancy but not in labor. Gardnerella vaginalis was associated with C4 activation both during pregnancy and labor. The amount of L. gasseri correlated with factor B activation during pregnancy but not during labor. Atopobium vaginae was more abundant during pregnancy than labor and correlated with C4 activation during labor and with factor B activation during pregnancy. Activation of the alternative pathway factor B was significantly stronger during pregnancy compared to labor. During labor complement activation may be inhibited by the abundant presence of factor H and FHL1.

Conclusions

These results indicate that bacterial composition of the vaginal microbiota could have a role in the local activation and regulation of complement-mediated inflammation during pregnancy. At the time of parturition complement activation appears to be more strictly regulated than during pregnancy.

Inflammation-related immune proteins in maternal plasma as potential predictive biomarkers for rescue cerclage outcome in women with cervical insufficiency

PROBLEM

This study aimed to determine whether various novel plasma mediators of immune regulation associated with inflammation could independently predict the clinical outcome of rescue cerclage in patients with cervical insufficiency (CI).

METHOD OF STUDY

A total of 41 singleton pregnant women (17-25 weeks) who underwent rescue cerclage for CI were retrospectively evaluated. Stored plasma samples were assayed for IGFBP-1, -2, -3, IL-6, latexin, LBP, lipocalin-2, M-CSF, MIP-1α, MMP-8, -9, pentraxin 3, resistin, S100A8, S100A8/A9, thrombospondin-2, TIMP-1, and TNFR2 levels. The primary outcome measures were spontaneous preterm birth (SPTB) at < 28 and < 34 weeks after cerclage placement.

RESULTS

Multivariate Firth's logistic regression analysis revealed that high levels of IGFBP-3 and S100A8/A9, and low levels of MIP-1α were significantly associated with SPTB at < 28 weeks after cerclage placement, whereas only low MIP-1α levels were significantly associated with SPTB at < 34 weeks, even after adjustment for baseline clinical covariates (e.g., cervical dilatation). For the prediction of SPTB at < 28 weeks, the area under the curves (AUC) of IGFBP-3, MIP-1α, and S100A8/A9 were of .686, .691, and .693, respectively. Similarly, the AUC of MIP-1 α was of .659 to predict SPTB at < 34 weeks.

CONCLUSIONS

These findings suggest that plasma IGFBP-3, MIP-1α, and S100A8/A9 can represent noninvasive independent biomarkers for identifying women with CI at high risk for SPTB following rescue cerclage. Nonetheless, further in large, multicenter clinical studies should be performed to confirm the clinical value of these biomarkers.

Human placental proteomics and exon variant studies link AAT/SERPINA1 with spontaneous preterm birth

BACKGROUND

Preterm birth is defined as live birth before 37 completed weeks of pregnancy, and it is a major problem worldwide. The molecular mechanisms that lead to onset of spontaneous preterm birth are incompletely understood. Prediction and evaluation of the risk of preterm birth is challenging as there is a lack of accurate biomarkers. In this study, our aim was to identify placental proteins that associate with spontaneous preterm birth.

METHODS

We analyzed the proteomes from placentas to identify proteins that associate with both gestational age and spontaneous labor. Next, rare and potentially damaging gene variants of the identified protein candidates were sought for from our whole exome sequencing data. Further experiments we performed on placental samples and placenta-associated cells to explore the location and function of the spontaneous preterm labor-associated proteins in placentas.

RESULTS

Exome sequencing data revealed rare damaging variants in SERPINA1 in families with recurrent spontaneous preterm deliveries. Protein and mRNA levels of alpha-1 antitrypsin/SERPINA1 from the maternal side of the placenta were downregulated in spontaneous preterm births. Alpha-1 antitrypsin was expressed by villous trophoblasts in the placenta, and immunoelectron microscopy showed localization in decidual fibrinoid deposits in association with specific extracellular proteins. siRNA knockdown in trophoblast-derived HTR8/SVneo cells revealed that SERPINA1 had a marked effect on regulation of the actin cytoskeleton pathway, Slit-Robo signaling, and extracellular matrix organization.

CONCLUSIONS

Alpha-1 antitrypsin is a protease inhibitor. We propose that loss of the protease inhibition effects of alpha-1 antitrypsin renders structures critical to maintaining pregnancy susceptible to proteases and inflammatory activation. This may lead to spontaneous premature birth.

Systematic review of preterm birth multi-omic biomarker studies

Preterm birth (PTB) is one of the leading causes of deaths in infants under the age of five. Known risk factors of PTB include genetic factors, lifestyle choices or infection. Identification of omic biomarkers associated with PTB could aid clinical management of women at high risk of early labour and thereby reduce neonatal morbidity. This systematic literature review aimed to identify and summarise maternal omic and multi-omic (genomics, transcriptomics, proteomics and metabolites) biomarker studies of PTB. Original research articles were retrieved from three databases: PubMed, Web of Science and Science Direct, using specified search terms for each omic discipline. PTB studies investigating genomics, transcriptomics, proteomics or metabolomics biomarkers prior to onset of labour were included. Data were collected and reviewed independently. Pathway analyses were completed on the biomarkers from non-targeted omic studies using Reactome pathway analysis tool. A total of 149 omic studies were identified; most of the literature investigated proteomic biomarkers. Pathway analysis identified several cellular processes associated with the omic biomarkers reported in the literature. Study heterogeneity was observed across the research articles, including the use of different gestation cut-offs to define PTB. Infection/inflammatory biomarkers were identified across majority of papers using a range of targeted and non-targeted approaches.

Is there a maternal blood biomarker that can predict spontaneous preterm birth prior to labour onset? A systematic review

Introduction

The ability to predict spontaneous preterm birth (sPTB) prior to labour onset is a challenge, and it is currently unclear which biomarker(s), may be potentially predictive of sPTB, and whether their predictive power has any utility. A systematic review was conducted to identify maternal blood biomarkers of sPTB.

Methods

This study was conducted according to PRISMA protocol for systematic reviews. Four databases (MEDLINE, EMBASE, CINAHL, Scopus) were searched up to September 2021 using search terms: “preterm labor”, “biomarker” and “blood OR serum OR plasma”. Studies assessing blood biomarkers prior to labour onset against the outcome sPTB were eligible for inclusion. Risk of bias was assessed based on the Newcastle Ottawa scale. Increased odds of sPTB associated with maternal blood biomarkers, as reported by odds ratios (OR), or predictive scores were synthesized. This review was not prospectively registered.

Results

Seventy-seven primary research articles met the inclusion criteria, reporting 278 unique markers significantly associated with and/or predictive of sPTB in at least one study. The most frequently investigated biomarkers were those measured during maternal serum screen tests for aneuploidy, or inflammatory cytokines, though no single biomarker was clearly predictive of sPTB based on the synthesized evidence. Immune and signaling pathways were enriched within the set of biomarkers and both at the level of protein and gene expression.

Conclusion

There is currently no known predictive biomarker for sPTB. Inflammatory and immune biomarkers show promise, but positive reporting bias limits the utility of results. The biomarkers identified may be more predictive in multi-marker models instead of as single predictors. Omics-style studies provide promising avenues for the identification of novel (and multiple) biomarkers. This will require larger studies with adequate power, with consideration of gestational age and the heterogeneity of sPTB to identify a set of biomarkers predictive of sPTB.

The neonatal PROC gene rs1799809 polymorphism modifies the association between prenatal air pollutants exposure and PROC promoter methylation

Prenatal air pollution, protein C (PROC) gene abnormal methylation, and genetic mutation can cause a series of neonatal diseases, but the complex relationship between them remains unclear. Here, we recruited 552 mothers and their own babies during January 2010-January 2012 in Zhengzhou to explore such association. The air pollutant data was obtained from the Environmental Monitoring Stations. The rs1799809 genotype and the methylation levels at the promoter region of PROC in genomic DNA samples were detected respectively by TaqMan probe and quantitative methylation specific PCR using real-time PCR system. The results show that the levels of neonatal PROC methylation were negatively associated with concentrations of NO₂ during the entire pregnancy, particularly during the third trimester. Of particular significance, only in newborns carrying rs1799809 AA genotype, negatively significant associations between PROC methylation levels and exposure concentrations of air pollutants were observed. Further, we observed a significant interactive effect between neonatal rs1799809 genotype and SO₂ exposure during the entire pregnancy on neonatal PROC methylation levels. Prenatal exposure to ambient air pollutants specifically was associated with the neonatal PROC promoter methylation level of newborns carrying the rs1799809 AA genotype. Taken together, these findings suggest that neonatal PROC methylation levels are associated with prenatal exposure to ambient air pollutants, and this association can be modified by rs1799809 genotype.

Maternal Plasma and Amniotic Fluid LBP, Pentraxin 3, Resistin, and IGFBP-3: Biomarkers of Microbial Invasion of Amniotic Cavity and/or Intra-amniotic Inflammation in Women with Preterm Premature Rupture of Membranes

BACKGROUND

We sought to determine whether lipopolysaccharide binding protein (LBP), pentraxin 3, resistin, and insulin-like growth factor binding protein (IGFBP)-3 in plasma and amniotic fluid (AF) can predict microbial invasion of the amniotic cavity (MIAC), intra-amniotic inflammation (IAI), and microbial-associated IAI in women with preterm premature rupture of membranes (PPROM).

METHODS

This was a retrospective cohort study involving 168 singleton pregnant women with PPROM. AF obtained via amniocentesis was cultured and assayed for interleukin (IL)-6 to define IAI and for IL-8 to compare with AF biomarkers. Plasma samples were collected at the time of amniocentesis, and C-reactive protein (CRP) levels in serum were compared with plasma biomarkers. The stored plasma and AF samples were assayed for LBP, pentraxin 3 (PTX3), resistin, and IGFBP-3 by ELISA.

RESULTS

Multivariate logistic regression analysis revealed that: 1) elevated plasma and AF levels of LBP were independently associated with increased risks of MIAC, IAI, and microbial-associated IAI; 2) elevated AF, but not plasma, PTX3, and resistin levels were independently associated with increased risks of MIAC, IAI, and microbial-associated IAI; 3) decreased IGFBP-3 levels in the plasma were independently associated with only IAI, whereas those in the AF were associated with only microbial-associated IAI. Among the tested biomarkers, AF PTX3 and resistin had the highest predictive performance for MIAC, IAI, and microbial-associated IAI (area under the curves [AUC] = 0.85-0.95), which is similar to the performance of AF IL-8. The AUCs of the plasma LBP and IGFBP-3 were similar to that of serum CRP with respect to IAI.

CONCLUSION

Maternal plasma LBP and IGFBP-3 are potential biomarkers for the non-invasive identification of IAI in women with PPROM, with a similar accuracy to the serum CRP level. AF LBP, PTX3, resistin, and IGFBP-3 may be involved in the intra-amniotic inflammatory responses in PPROM complicated by MIAC.

Proteomic identification of novel plasma biomarkers associated with spontaneous preterm birth in women with preterm labor without infection/inflammation

Objective

We sought to identify plasma biomarkers associated with spontaneous preterm birth (SPTB, delivery within 21 days of sampling) in women with preterm labor (PTL) without intra-amniotic infection/inflammation (IAI) using label-free quantitative proteomic analysis, as well as to elucidate specific protein pathways involved in these cases.

Methods

This was a retrospective cohort study comprising 104 singleton pregnant women with PTL (24–32 weeks) who underwent amniocentesis and demonstrated no evidence of IAI. Analysis of pooled plasma samples collected from SPTB cases and term birth (TB) controls (n = 10 for each group) was performed using label-free quantitative mass spectrometry for proteome profiling in a nested case-control study design. Eight candidate proteins of interest were validated by ELISA-based assay and a clot-based assay in the total cohort.

Results

Ninety-one proteins were differentially expressed (P < 0.05) in plasma samples obtained from SPTB cases, of which 53 (58.2%) were upregulated and 38 (41.8%) were downregulated when compared to TD controls. A validation study confirmed that plasma from women who delivered spontaneously within 21 days of sampling contained significantly higher levels of coagulation factor Ⅴ and lower levels of S100 calcium binding protein A9 (S100A9), especially the former which was independent of baseline variables. The top-ranked pathways related to the 91 differentially expressed proteins were liver-X-receptor/retinoid X receptor (RXR) activation, acute phase response signaling, farnesoid X receptor/RXR activation, coagulation system, and complement system.

Conclusions

Proteomic analyses in this study identified potential novel biomarkers (i.e., coagulation factor V and S100A9) and potential protein pathways in plasma associated with SPTB in the absence of IAI in women with PTL. The present findings provide novel insights into the molecular pathogenesis and therapeutic targets specific for idiopathic SPTB.

Advances in Aptamer-Based Biomarker Discovery

The discovery and identification of biomarkers promote the rational and fast development of medical diagnosis and therapeutics. Clinically, the application of ideal biomarkers still is limited due to the suboptimal technology in biomarker discovery. Aptamers are single-stranded deoxyribonucleic acid or ribonucleic acid molecules and can selectively bind to varied targets with high affinity and specificity. Compared with antibody, aptamers have desirable advantages, such as flexible design, easy synthesis and convenient modification with different functional groups. Currently, different aptamer-based technologies have been developed to facilitate biomarker discovery, especially CELL-SELEX and SOMAScan technology. CELL-SELEX technology is mainly used to identify cell membrane surface biomarkers of various cells. SOMAScan technology is an unbiased biomarker detection method that can analyze numerous and even thousands of proteins in complex biological samples at the same time. It has now become a large-scale multi-protein biomarker discovery platform. In this review, we introduce the aptamer-based biomarker discovery technologies, and summarize and highlight the discovered emerging biomarkers recently in several diseases.

Activation of the Complement System in the Lower Genital Tract During Pregnancy and Delivery

Background

Human pregnancy alters profoundly the immune system. The local involvement and mechanisms of activation of the complement system in the cervicovaginal milieu during pregnancy and delivery remain unexplored.

Objectives

To determine whether normal pregnancy and delivery are associated with local activation of complement or changes in the immunoglobulin profile in the cervix.

Study Design

This study was designed to assess IgA, IgG, and complement activation in the cervicovaginal area in three groups of patients: i) 49 pregnant women (week 41+3–42+0) not in active labor, ii) 24 women in active labor (38+4–42+2), and iii) a control group of nonpregnant women (n=23) at child-bearing age. We collected mucosal samples from the lateral fornix of the vagina and external cervix during routine visits and delivery. The Western blot technique was used to detect complement C3 and its activation products. For semiquantitative analysis, the bands of the electrophoresed proteins in gels were digitized on a flatbed photo scanner and analyzed. IgA and IgG were analyzed by Western blotting and quantified by ELISA. One-way ANOVA and Tukey’s Multiple Comparison tests were used for statistical comparisons.

Results

A higher abundance but lower activation level of C3 in both the external cervix (P<0.001) and lateral fornix of the vagina (P<0.001) was observed during delivery (58 ± 22, n= 24) in comparison to the groups of nonpregnant (72 ± 13%; mean ± SD, n=23) and pregnant women (78 ± 22%, n=49). Complement activating IgG was detected in higher abundance than IgA in the cervicovaginal secretions of pregnant women. In a small proportion samples also C3-IgG complexes were detected.

Conclusions

Our results reveal an unexpectedly strong activation of the complement system and the presence IgG immunoglobulins in the cervicovaginal area during pregnancy, active labor, and among nonpregnant women. In contrast to the higher amounts of C3 in the cervicovaginal secretions during labor, its activation level was lower. Complement activating IgG was detected in higher concentrations than IgA in the mucosal secretions during pregnancy and labor. Taken together our results imply the presence a locally operating humoral immune system in the cervicovaginal mucosa.

Identifying potential biomarkers related to pre-term delivery by proteomic analysis of amniotic fluid

We sought to identify biomarkers in the amniotic fluid (AF) and specific signaling pathways related to spontaneous preterm delivery (SPTD, < 34 weeks) in women with preterm labor (PTL) without intra-uterine infection/inflammation (IUI). This was a retrospective cohort study of a total of 139 PTL women with singleton gestation (24 + 0 to 32 + 6 weeks) who underwent amniocentesis and who displayed no evidence of IUI. A nested case-control was conducted using pooled AF samples (n = 20) analyzed via label-free liquid chromatography-tandem mass spectrometry. In the total cohort, an ELISA validation study was performed for seven candidate proteins of interest. Proteomic analysis identified 77 differentially expressed proteins (DEPs, P < 0.05) in the AF from SPTD cases compared to term delivery controls. ELISA validation confirmed that women who had an SPTD before 34 weeks had significantly independently lower levels of VEGFR-1 and higher levels of lipocalin-2 and the Fc fragment of IgG binding protein in the AF. Five principle pathways associated with the 77 DEPs were identified, including glycolysis, gluconeogenesis, and iron homeostasis. The proteomic analysis data of AFs from women with PTL identified several novel biomarkers and specific protein pathways related to SPTD in the absence of IUI.

EBF1-Correlated Long Non-coding RNA Transcript Levels in 3rd Trimester Maternal Blood and Risk of Spontaneous Preterm Birth

Biomarkers associated with spontaneous preterm birth (sPTB) before labor onset could aid in prediction, triage, and stratification for testing interventions. In this study we examined maternal blood EBF1-correlated long non-coding RNAs (lncRNAs) in relation to sPTB. We retrieved all lncRNA transcripts from a public gene expression dataset (GSE59491) derived from maternal blood in trimesters 2 and 3 from a Canadian cohort with a matched set of sPTB (n = 51) and term births (n = 106). LncRNA transcripts differentially expressed (limma moderated t-tests) in sPTB vs. term were tested for correlations (Pearson) with EBF1 mRNA levels in the same blood samples. Using logistic regression, EBF1-correlated lncRNAs were divided into tertiles and assessed in relation to odds of sPTB. Two lncRNA transcripts in the 3rd trimester maternal blood were differentially expressed between sPTB and term births (all p < 0.001 and FDR < 0.250) and positively and negatively correlated with EBF1 mRNA levels. They were as follows: (1) LINC00094 r = 0.196 (95% CI: 0.039 to 0.344), p = 0.015, and BH adjusted p = 0.022 and (2) LINC00870 r = - 0.303 (95% CI: - 0.441 to - 0.152), p < 0.001, and BH adjusted p < 0.001. As compared with term births, sPTBs were more likely to be in the highest tertile of LINC00870 (odds ratio (OR) = 4.08 (95% CI 1.60, 10.40), p = 0.003) and the lowest tertile of LINC00094 (OR = 5.16 (95% CI 1.96, 13.61), p < 0.001). Two sPTB-associated EBF1-correlated lncRNAs (LINC00870 and LINC00094) had multiple potential enhancers containing EBF1 binding site(s). Our current findings, along with previous reports linking EBF1 and sPTB, motivate additional research on the EBF1 gene-related gene expression and regulation in relation to sPTB within other cohorts and within laboratory-based models.

Plasma Biomarkers of Reticular Pseudodrusen and the Risk of Progression to Advanced Age-Related Macular Degeneration

Purpose

To determine, using an aptamer-based technology in patients with intermediate age-related macular degeneration (AMD), (1) if there is a difference in plasma levels of 4979 proteins in patients with and without reticular pseudodrusen (RPD), and (2) if plasma levels of proteins are related to time to conversion to advanced AMD.

Methods

Patients with intermediate AMD and RPD were identified from an AMD registry. Relative concentrations of each protein were log (base 2) transformed and compared between patients with and without RPD using linear regression. A Cox proportional hazards survival model was fit to each aptamer to quantify associations with time to conversion. A pathway analysis was conducted in converters versus non-converters using the Reactome database.

Results

Of the 109 intermediate AMD patients, 39 had bilateral RPD (36%). Two proteins, TCL1A and CNDP1, were lower in patients in the intermediate AMD group with RPD. Twenty-one patients converted to advanced AMD with a median time to conversion of 25.2 months (range, 2.3-48.5 months) and median follow-up time in non-converters of 26.4 months (range, 0.03-49.7 months). Several proteins (lysozyme C, TFF3, RNAS6, and SAP3) distinguished patients who converted from those who did not convert to advanced AMD. The top conversion pathways included tumor necrosis factors bind their physiological receptors, digestion and absorption, signaling by activin, and signaling by TGF-β family members.

Conclusions

We identified a protein signature related to RPD, as well as to conversion to advanced AMD. The pathway analysis suggests that dysfunction of critical systemic pathways may have links to conversion to advanced AMD.

Translational Relevance

Biomarkers identified in plasma likely reflect systemic alterations in protein expression in patients with intermediate AMD.

Cervicovaginal fluid proteomic analysis to identify potential biomarkers for preterm birth

BACKGROUND

Spontaneous preterm birth is a leading cause of neonatal morbidity and mortality. Early identification of at-risk women by reliable screening tests could reduce the spontaneous preterm birth rate, but conventional methods such as obstetrical history and maternal cervical length screening identify only a minority of spontaneous preterm birth cases. Cervicovaginal fluid might prove to be a useful, readily available biological fluid for identifying spontaneous preterm birth biomarkers.

OBJECTIVE

The objective of the study was to identify cervicovaginal fluid biomarkers of early spontaneous preterm birth in a high-risk cohort of pregnant women with a history of spontaneous preterm birth using targeted and shotgun proteomic analyses.

STUDY DESIGN

A nested case control study (cases were spontaneous preterm birth <34 weeks in the current pregnancy; controls were spontaneous labor and delivery at 39-41 weeks) was performed using cervicovaginal fluid samples collected at 3 study visits (100/7 to 186/7 weeks, 190/7 to 236/7 weeks, and 280/7 to 316/7 weeks). All participants had a history of at least 1 prior spontaneous preterm birth. Targeted proteomic analysis was performed using a stable isotope-labeled proteome derived from endocervical and vaginal mucosal cells. This served as a standard to quantitate candidate protein levels in individual cervicovaginal fluid samples from the second and third study visits using liquid chromatography-multiple reaction monitoring mass spectrometry. The ratio of endogenous peptide area/stable isotope-labeled proteome-derived peptide area was used to measure levels of 42 peptides in 22 proteins. To maximize biomarker discovery in the cervicovaginal fluid samples, shotgun proteomic analysis also was performed utilizing liquid chromatography and ion trap mass spectrometry. A validation study was performed in second-trimester cervicovaginal fluid samples from an independent study group (12 spontaneous preterm birth cases, 19 term delivery controls) using enzyme-linked immunosorbent assay for 5 proteins expressed at higher levels in spontaneous preterm birth cases compared with controls in targeted or shotgun proteomic analyses.

RESULTS

For targeted proteomics, cervicovaginal fluid samples from 33 cases and 32 controls at 190/7 to 236/7 weeks and 16 cases and 14 controls at 280/7 to 316/7 weeks from the same pregnancies were analyzed. When samples were compared between cases and controls, the relative abundance of 5 proteins was greater (P = .02-.05) in cases at both visits, while the relative abundance of 1 protein was lower (P = .03) in cases at both visits. For shotgun proteomics analyses, cervicovaginal fluid samples were pooled for 9 spontaneous preterm birth cases and 9 term delivery controls at each study visit. Shotgun proteomics yielded 28 proteins that were detected at levels >2 times higher and 1 protein that was detected at a level <0.5 times lower in spontaneous preterm birth cases compared with controls at all 3 study visits. Validation enzyme-linked immunosorbent assay for 5 proteins that were detected at higher levels in cervicovaginal fluid samples from spontaneous preterm birth cases compared with term delivery controls in proteomics analyses did not demonstrate statistically significant differences between spontaneous preterm birth cases and controls.

CONCLUSIONS

Potential biomarkers of spontaneous preterm birth were identified by targeted and shotgun proteomics analyses in cervicovaginal fluid samples from high-risk, asymptomatic women. Many of the proteins detected at higher levels in cervicovaginal fluid samples from spontaneous preterm birth cases are extracellular matrix proteins and/or regulate cell membrane physiology. These proteins have substantial biological interest, but validation enzyme-linked immunosorbent assay for 5 of these proteins did not yield clinically useful biomarkers for spontaneous preterm birth.

Early angiogenic proteins associated with high risk for bronchopulmonary dysplasia and pulmonary hypertension in preterm infants

Early pulmonary vascular disease in preterm infants is associated with the subsequent development of bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH); however, mechanisms that contribute to or identify infants with increased susceptibility for BPD and/or PH are incompletely understood. Therefore, we tested if changes in circulating angiogenic peptides during the first week of life are associated with the later development of BPD and/or PH. We further sought to determine alternate peptides and related signaling pathways with the risk for BPD or PH. We prospectively enrolled infants with gestational age <34 wk and collected blood samples during their first week of life. BPD and PH were assessed at 36 wk postmenstrual age. Samples were assayed for each of the 1,121 peptides included in the SOMAscan scan technology, with subsequent pathway analysis. Of 102 infants in the study, 82 had BPD, and 13 had PH. Multiple angiogenic proteins (PF-4, VEGF121, ANG-1, bone morphogenetic protein 10 [BMP10], hepatocyte growth factor (HGF), ANG-2) were associated with the subsequent diagnosis of BPD; and FGF-19, PF-4, connective tissue activating peptide (CTAP)-III, and PDGF-AA levels were associated with BPD severity. Early increases in BMP10 was strongly associated with the late risk for BPD and PH. We found that early alterations of circulating angiogenic peptides and others were associated with the subsequent development of BPD. We further identified peptides that were associated with BPD severity and BPD-associated PH, including BMP10. We speculate that proteomic biomarkers during the first week of life may identify infants at risk for BPD and/or PH to enhance care and research.

Proteomic Analysis of Amniotic Fluid Proteins for Predicting the Outcome of Emergency Cerclage in Women with Cervical Insufficiency

We aimed to identify novel biomarkers in amniotic fluid (AF) that predict the outcome of emergency cerclage in women with cervical insufficiency. This retrospective cohort study included 40 singleton pregnant women who received emergency cerclage for cervical insufficiency (17-25 weeks) and underwent amniocentesis. Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify AF proteins in pooled samples (n = 16) using a nested case-control approach. The six candidate biomarkers of interest were validated by enzyme-linked immunosorbent assays (ELISA) in the final cohort (n = 40). The differentially expressed proteins (DEPs) were analyzed by pathway analysis software. The primary outcome measure was failure of emergency cerclage [defined as spontaneous preterm delivery (SPTD) at < 34 weeks of gestation after cerclage placement]. Sixty-eight proteins were differentially expressed (P < 0.001) in AF from SPTD cases and near-term controls, of which 44 (64.7%) were upregulated and 24 (35.3%) were downregulated. Validation by ELISA confirmed that AF from women with cerclage failure contained significantly higher levels of myeloperoxidase, lactoferrin, glucose-6-phosphate isomerase, lipocalin-2, and lymphocyte cytosolic protein 1, the first four of which were independent of cervical dilatation at presentation. The five pathways with the most differentially regulated proteins were actin cytoskeleton signaling, acute phase response signaling, ILK signaling, glycolysis, and gluconeogenesis. Proteomic analyses of AF in this study identified DEPs and specific protein pathways related to poor prognosis after emergency cerclage for cervical insufficiency. Four novel independent biomarkers in AF for cerclage failure have been identified using proteomics.

Alterations in complement and coagulation pathways of human placentae subjected to in vitro fertilization and embryo transfer in the first trimester

The mechanisms underlying the potential risks of in vitro fertilization and embryo transfer (IVF-ET) have not been fully elucidated. The aim of this study was to explore changes in the complement and coagulation pathways in placentae subjected to IVF-ET in the first trimester compared to placentae from normal pregnancies. Four placenta samples in the first trimester were obtained from patients undergoing IVF-ET owing to oviductal factors only. An additional 4 control placentae were obtained from volunteers with normal pregnancies. A GeneChip Affymetrix HG-U133 Plus 2.0 Array was utilized to analyze the changes in gene expression between the normal and IVF-ET placentae. Differentially expressed genes (DEGs) were analyzed using the Database for Annotation and Visualization and Integrated Discovery bioinformatics resource, and gene ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted. Using real-time PCR, we confirmed the obtained microarray data in 10 dysregulated genes. Five of the gene products were further analyzed by immunohistochemistry (IHC) to determine their protein expression and localization. A total of fifty DEGs were identified in the complement and coagulation pathways in the IVF-ET treated placentae: 38 upregulated and 12 down-regulated. KEGG pathway analysis indicated that IVF-ET manipulation substantially over-activated the coagulation and complement pathways, while urokinase plasminogen activator- and urokinase plasminogen activator receptor-mediated trophoblastic invasion and tissue remodeling were inhibited. Furthermore, the 5 proteins analyzed by IHC were found to be localized specifically to the placenta. This is the first study to compare DEGs relating to the placental complement and coagulation pathways from patients undergoing IVF-ET treatment compared to those undergoing normal pregnancy. These findings identified valuable biomarkers and potential novel therapeutic targets to combat the unfavorable effects of IVF-ET.

The role of complement in preterm birth and prematurity

Complications of preterm birth (PTB) are the global leading cause of death in children younger than 5 years of age. Almost 15 million children are born prematurely in the world each year. Increasing evidence suggests that labor and delivery have many hallmarks of an inflammatory reaction, where complement activation has an active participation. As one of the most important components of inflammation, the role of complement during labor and PTB is becoming an attractive research target. The complement components C1q and C5b-9 are deposited on fetal membranes and release inflammatory mediators that contribute to uterine contractions, cervical ripening, cell chemotaxis, metalloproteinases production, membrane awaking and rupture, and it participates as a co-adjuvant in the onset and progress of labor. This article reviews a basic description of the complement system, its role in preterm birth and current concepts regarding its contribution in novel therapy strategies and new biomarkers.

The prediction of early preeclampsia: Results from a longitudinal proteomics study

OBJECTIVES

To identify maternal plasma protein markers for early preeclampsia (delivery <34 weeks of gestation) and to determine whether the prediction performance is affected by disease severity and presence of placental lesions consistent with maternal vascular malperfusion (MVM) among cases.

STUDY DESIGN

This longitudinal case-control study included 90 patients with a normal pregnancy and 33 patients with early preeclampsia. Two to six maternal plasma samples were collected throughout gestation from each woman. The abundance of 1,125 proteins was measured using high-affinity aptamer-based proteomic assays, and data were modeled using linear mixed-effects models. After data transformation into multiples of the mean values for gestational age, parsimonious linear discriminant analysis risk models were fit for each gestational-age interval (8-16, 16.1-22, 22.1-28, 28.1-32 weeks). Proteomic profiles of early preeclampsia cases were also compared to those of a combined set of controls and late preeclampsia cases (n = 76) reported previously. Prediction performance was estimated via bootstrap.

RESULTS

We found that 1) multi-protein models at 16.1-22 weeks of gestation predicted early preeclampsia with a sensitivity of 71% at a false-positive rate (FPR) of 10%. High abundance of matrix metalloproteinase-7 and glycoprotein IIbIIIa complex were the most reliable predictors at this gestational age; 2) at 22.1-28 weeks of gestation, lower abundance of placental growth factor (PlGF) and vascular endothelial growth factor A, isoform 121 (VEGF-121), as well as elevated sialic acid binding immunoglobulin-like lectin 6 (siglec-6) and activin-A, were the best predictors of the subsequent development of early preeclampsia (81% sensitivity, FPR = 10%); 3) at 28.1-32 weeks of gestation, the sensitivity of multi-protein models was 85% (FPR = 10%) with the best predictors being activated leukocyte cell adhesion molecule, siglec-6, and VEGF-121; 4) the increase in siglec-6, activin-A, and VEGF-121 at 22.1-28 weeks of gestation differentiated women who subsequently developed early preeclampsia from those who had a normal pregnancy or developed late preeclampsia (sensitivity 77%, FPR = 10%); 5) the sensitivity of risk models was higher for early preeclampsia with placental MVM lesions than for the entire early preeclampsia group (90% versus 71% at 16.1-22 weeks; 87% versus 81% at 22.1-28 weeks; and 90% versus 85% at 28.1-32 weeks, all FPR = 10%); and 6) the sensitivity of prediction models was higher for severe early preeclampsia than for the entire early preeclampsia group (84% versus 71% at 16.1-22 weeks).

CONCLUSION

We have presented herein a catalogue of proteome changes in maternal plasma proteome that precede the diagnosis of preeclampsia and can distinguish among early and late phenotypes. The sensitivity of maternal plasma protein models for early preeclampsia is higher in women with underlying vascular placental disease and in those with a severe phenotype.

Circulating microparticle proteins obtained in the late first trimester predict spontaneous preterm birth at less than 35 weeks' gestation: a panel validation with specific characterization by parity

BACKGROUND

We have previously shown that protein biomarkers associated with circulating microparticles proteins (CMPs) obtained at the end of the first trimester may detect physiologic changes in maternal-fetal interaction such that the risk of spontaneous preterm delivery ≤35 weeks can be stratified.

OBJECTIVES

We present here a study extension and validation of the CMP protein multiplex concept using a larger sample set from a multicenter population that allows for model derivation in a training set and characterization in a separate testing set.

MATERIALS AND METHODS

Ethylenediaminetetraacetic acid (EDTA) plasma was obtained from 3 established biobanks (Seattle, Boston, and Pittsburgh). Samples were from patients at a median of 10-12 weeks' gestation, and the CMPs were isolated via size-exclusion chromatography followed by protein identification via targeted protein analysis using liquid chromatography-multiple reaction monitoring-mass (LC-MRM) spectrometry. A total of 87 women delivered at ≤35 weeks, and 174 women who delivered at term were matched by maternal age (±2 years) and gestational age at sample draw (±2 weeks). From our prior work, the CMP protein multiplex comprising F13A, FBLN1, IC1, ITIH2, and LCAT was selected for validation.

RESULTS

For delivery at ≤35 weeks, the receiver operating characteristic (ROC) curve for a panel of CMP proteins (F13A, FBLN1, IC1, ITIH2, and LCAT) revealed an associated area under the ROC curve (AUC) of 0.74 (95% CI, 0.63-0.81). A separate panel of markers (IC1, LCAT, TRFE, and ITIH4), which stratified risk among mothers with a parity of 0, showed an AUC of 0.77 (95% CI, 0.61-0.90).

CONCLUSION

We have identified a set of CMP proteins that provide, at 10-12 weeks gestation, a clinically useful AUC in an independent test population. Furthermore, we determined that parity is pertinent to the diagnostic testing performance of the biomarkers for risk stratification.

IUGR Is Associated With Marked Hyperphosphorylation of Decidual and Maternal Plasma IGFBP-1

CONTEXT

The mechanisms underpinning intrauterine growth restriction (IUGR), as a result of placental insufficiency, remain poorly understood, no specific treatment is available, and clinically useful biomarkers for early detection are lacking.

OBJECTIVE

We hypothesized that human IUGR is associated with inhibition of mechanistic target of rapamycin (mTOR) and activation of amino acid response (AAR) signaling, increased protein kinase casein kinase-2 (CK2) activity, and increased insulin-like growth factor-binding protein 1 (IGFBP-1) expression and phosphorylation in decidua and that maternal plasma IGFBP-1 hyperphosphorylation in the first trimester predicts later development of IUGR.

DESIGN, SETTING, AND PARTICIPANTS

Decidua [n = 16 appropriate-for-gestational age (AGA); n = 16 IUGR] and maternal plasma (n = 13 AGA; n = 13 IUGR) were collected at delivery from two different cohorts. In addition, maternal plasma was obtained in the late first trimester from a third cohort of women (n = 7) who later delivered an AGA or IUGR infant.

MAIN OUTCOME MEASURES

Total IGFBP-1 expression and phosphorylation (Ser101/Ser119/Ser169), mTOR, AAR, and CK2 activity in decidua and IGFBP-1 concentration and phosphorylation in maternal plasma.

RESULTS

We show that decidual IGFBP-1 expression and phosphorylation are increased, mTOR is markedly inhibited, and AAR and CK2 are activated in IUGR. Moreover, IGFBP-1 hyperphosphorylation in first-trimester maternal plasma is associated with the development of IUGR.

CONCLUSIONS

These data are consistent with the possibility that the decidua functions as a nutrient sensor linking limited oxygen and nutrient availability to increased IGFBP-1 phosphorylation, possibly mediated by mTOR and AAR signaling. IGFBP-1 hyperphosphorylation in first-trimester maternal plasma may serve as a predictive IUGR biomarker, allowing early intervention.

Proteomic Profiles in Advanced Age-Related Macular Degeneration Using an Aptamer-Based Proteomic Technology

Purpose

To explore top-ranked plasma proteins related to neovascular age-related macular degeneration (AMD) and geographic atrophy (GA), and explore pathways related to neovascular AMD and GA.

Methods

We conducted a pilot study of patients with neovascular AMD (n = 10), GA (n = 10), and age-matched cataract controls (n = 10) who were recruited into an AMD registry. We measured 4001 proteins in ethylenediaminetetraacetic acid plasma samples using an aptamer-based proteomic technology. Relative concentrations of each of 4001 proteins were log (base 2) transformed and compared between cases of neovascular AMD and GA versus controls using linear regression. Pathway analysis was conducted using pathways downloaded from Reactome.

Results

In this pilot study, higher levels of vinculin and lower levels of CD177 were found in patients with neovascular AMD compared with controls. Neuregulin-4 was higher and soluble intercellular adhesion molecule-1 was lower in patients with GA compared with controls. For neovascular AMD, cargo trafficking to the periciliary membrane, fibroblast growth factor receptor 3b ligand binding and activation, and vascular endothelial growth factor–related pathways were in the top ranked pathways. The top-ranked pathways for GA included several related to ErbB4 signaling.

Conclusions

We found different proteins and different pathways associated with neovascular AMD and GA. Vinculin and some of the top-ranked pathways have been previously associated with AMD, whereas others have not been described.

Translational Relevance

Biomarkers identified in plasma likely reflect systemic alterations in protein expression and may improve our understanding of the mechanisms leading to AMD.

Complement Activation During Early Pregnancy and Clinical Predictors of Preterm Birth in African American Women

Complement activation is essential for select physiologic processes during pregnancy; however, excess activation has been associated with an increased risk for preterm birth (PTB). African American (AA) women experience disproportionately higher rates of inflammation-associated PTB than other groups of women; thus, the purpose of this study was to explore the relationship between complement activation and perinatal outcomes among AA women. A plasma sample was collected between 8 and 14 weeks' gestation from a cohort of healthy AA women (N = 144) enrolled in a larger PTB cohort study. Medical record review was conducted to collect information on clinical factors (cervical length, health behaviors, gestational age at delivery). Multiple regression analysis was used to explore the relationships between complement marker (C3a/Bb) concentrations and the outcomes of interest after adjusting for baseline characteristics. C3a/Bb concentrations were not significant predictors of the gestational age at delivery, cervical length, or behavioral risk factors for PTB in this sample. Complement markers may not influence pregnancy outcomes among AA women in the same way as in predominantly white populations; however, more studies are needed to define complement dysregulation and the relationship with outcomes among AA women.

The human placental proteome secreted into the maternal and fetal circulations in normal pregnancy based on 4-vessel sampling

We sought to identify proteins secreted by the human placenta into the maternal and fetal circulations. Blood samples from the maternal radial artery and uterine vein and umbilical artery and vein were obtained during cesarean section in 35 healthy women with term pregnancy. Slow off-rate modified aptamer (SOMA) protein-binding technology was used to quantify 1310 known proteins. The uteroplacental and umbilical venoarterial concentration differences were calculated. Thirty-four proteins were significantly secreted by the placenta into the maternal circulation, including placental growth factor, growth/differentiation factor 15, and matrix metalloproteinase 12. There were 341 proteins significantly secreted by the placenta into the fetal circulation. Only 7 proteins were secreted into both the fetal and maternal circulations, suggesting a distinct directionality in placental protein release. We examined changes across gestation in the proteins found to be significantly secreted by the placenta into the maternal circulation using serial blood samples from healthy women. Among the 34 proteins secreted into the maternal circulation, 8 changed significantly across gestation. The identified profiles of secreted placental proteins will allow us to identify novel minimally invasive biomarkers for human placental function across gestation and discover previously unknown proteins secreted by the human placenta that regulate maternal physiology and fetal development.-Michelsen, T. M., Henriksen, T., Reinhold, D., Powell, T. L., Jansson, T. The human placental proteome secreted into the maternal and fetal circulations in normal pregnancy based on 4-vessel sampling.

Periodontal diseases and adverse pregnancy outcomes: Is there a role for vitamin D?

Studies have shown a relationship between maternal periodontal diseases (PDs) and premature delivery. PDs are commonly encountered oral diseases which cause progressive damage to the periodontal ligament and alveolar bones, leading to loss of teeth and oral disabilities. PDs also adversely affect general health by worsening of cardiovascular and metabolic diseases. Moreover, maternal PDs are thought to be related to increasing the frequency of preterm-birth with low birth weight (PBLBW) in new-borns. Prematurity and immaturity are the leading causes of prenatal and infant mortality and is a major public health problem around the world. Inflamed periodontal tissues generate significantly high levels of proinflammatory cytokines that may have systemic effects on the host mother and the fetus. In addition, the bacteria that cause PDs produce endotoxins which can harm the fetus. Furthermore, studies have shown that microorganisms causing PDs can get access to the bloodstream, invading uterine tissues, to induce PBLBW. Another likely mechanism that connects PDs with adverse pregnancy outcome is maternal vitamin D status. A role of inadequate vitamin D status in the genesis of PDs has been reported. Administration of vitamin D supplementation during pregnancy could reduce the risk of maternal infections and adverse pregnancy outcomes. As maternal PDs are significant risk factors for adverse pregnancy outcome, preventive antenatal care for pregnant women in collaboration with the obstetric and dental professions are required.

Proteomic analysis of first trimester maternal serum to identify candidate biomarkers potentially predictive of spontaneous preterm birth

Spontaneous preterm birth (sPTB) remains a major clinical dilemma; current diagnostics and interventions have not reduced the rate of this serious healthcare burden. This study characterizes differential protein profiles and post-translational modifications (PTMs) in first trimester maternal serum using a refined top-down approach coupling two-dimensional gel electrophoresis (2DE) and mass spectrometry (MS) to directly compare subsequent term and preterm labour events and identify marked protein differences. 30 proteoforms were found to be significantly increased or decreased in the sPTB group including 9 phosphoproteins and 11 glycoproteins. Changes occurred in proteins associated with immune and defence responses. We identified protein species that are associated with several clinically relevant biological processes, including interrelated biological networks linked to regulation of the complement cascade and coagulation pathways, immune modulation, metabolic processes and cell signalling. The finding of altered proteoforms in maternal serum from pregnancies that delivered preterm suggests these as potential early biomarkers of sPTB and also possible mediators of the disorder.

BIOLOGICAL SIGNIFICANCE

Identifying changes in protein profiles is critical in the study of cell biology, and disease treatment and prevention. Identifying consistent changes in the maternal serum proteome during early pregnancy, including specific protein PTMs (e.g. phosphorylation, glycosylation), is likely to provide better opportunities for prediction, intervention and prevention of preterm birth. This is the first study to examine first trimester maternal serum using a highly refined top-down proteomic analytical approach based on high resolution 2DE coupled with mass spectrometry to directly compare preterm (<37 weeks) and preterm (≥37 weeks) events and identify select protein differences between these conditions. As such, the data present a promising avenue for translation of biomarker discovery to a clinical setting as well as for future investigation of underlying aetiological processes.

Translational Systems Pharmacology Studies in Pregnant Women

Pregnancy involves rapid physiological adaptation and complex interplay between mother and fetus. New analytic technologies provide large amounts of genomic, proteomic, and metabolomics data. The integration of these data through bioinformatics, statistical, and systems pharmacology techniques can improve our understanding of the mechanisms of normal maternal physiologic changes and fetal development. New insights into the mechanisms of pregnancy‐related disorders, such as preterm birth (PTB), may lead to the development of new therapeutic interventions and novel biomarkers.

Complement activation, a threat to pregnancy

Pregnancy poses a challenge for the immune systems of placental mammals. As fetal tissues are semi-allogeneic and alloantibodies that commonly develop in the mother, the fetus and the placenta might be subject to complement-mediated immune attack with the potential risk of adverse pregnancy outcomes. Here, I describe how the use of animal models was pivotal in demonstrating that complement inhibition at the fetomaternal interface is essential for a successful pregnancy. Studies in animals also helped the identification of uncontrolled complement activation as a crucial effector in the pathogenesis of recurrent miscarriages, intrauterine growth restriction, preeclampsia, and preterm birth. Clinical studies employing complement biomarkers in plasma and urine showed an association between dysregulation of the complement system and adverse pregnancy outcomes. A better understanding of the role of the complement system in pregnancy complications will allow a rational approach to manipulate its activation as a potential therapeutic strategy with the goal of protecting pregnancies and improving long-term outcomes for mother and child.

The maternal plasma proteome changes as a function of gestational age in normal pregnancy: a longitudinal study

OBJECTIVE

Pregnancy is accompanied by dramatic physiological changes in maternal plasma proteins. Characterization of the maternal plasma proteome in normal pregnancy is an essential step for understanding changes to predict pregnancy outcome. The objective of this study was to describe maternal plasma proteins that change in abundance with advancing gestational age and determine biological processes that are perturbed in normal pregnancy.

STUDY DESIGN

A longitudinal study included 43 normal pregnancies that had a term delivery of an infant who was appropriate for gestational age without maternal or neonatal complications. For each pregnancy, 3 to 6 maternal plasma samples (median, 5) were profiled to measure the abundance of 1125 proteins using multiplex assays. Linear mixed-effects models with polynomial splines were used to model protein abundance as a function of gestational age, and the significance of the association was inferred via likelihood ratio tests. Proteins considered to be significantly changed were defined as having the following: (1) >1.5-fold change between 8 and 40 weeks of gestation; and (2) a false discovery rate-adjusted value of P < .1. Gene ontology enrichment analysis was used to identify biological processes overrepresented among the proteins that changed with advancing gestation.

RESULTS

The following results were found: (1) Ten percent (112 of 1125) of the profiled proteins changed in abundance as a function of gestational age; (2) of the 1125 proteins analyzed, glypican-3, sialic acid-binding immunoglobulin-type lectin-6, placental growth factor, C-C motif-28, carbonic anhydrase 6, prolactin, interleukin-1 receptor 4, dual-specificity mitogen-activated protein kinase 4, and pregnancy-associated plasma protein-A had more than a 5-fold change in abundance across gestation (these 9 proteins are known to be involved in a wide range of both physiological and pathological processes, such as growth regulation, embryogenesis, angiogenesis immunoregulation, inflammation etc); and (3) biological processes associated with protein changes in normal pregnancy included defense response, defense response to bacteria, proteolysis, and leukocyte migration (false discovery rate, 10%).

CONCLUSION

The plasma proteome of normal pregnancy demonstrates dramatic changes in both the magnitude of changes and the fraction of the proteins involved. Such information is important to understand the physiology of pregnancy and the development of biomarkers to differentiate normal vs abnormal pregnancy and determine the response to interventions.

The Microbiome and Complement Activation: A Mechanistic Model for Preterm Birth

Preterm birth (PTB, <37 completed weeks' gestation) is one of the leading obstetrical problems in the United States, affecting approximately one of every nine births. Even more concerning are the persistent racial disparities in PTB, with particularly high rates among African Americans. There are several recognized pathophysiologic pathways to PTB, including infection and/or exaggerated systemic or local inflammation. Intrauterine infection is a causal factor linked to PTB thought to result most commonly from inflammatory processes triggered by microbial invasion of bacteria ascending from the vaginal microbiome. Trials to treat various infections have shown limited efficacy in reducing PTB risk, suggesting that other complex mechanisms, including those associated with inflammation, may be involved in the relationship between microbes, infection, and PTB. The complement system, a key mediator of the inflammatory response, is an innate defense mechanism involved in both normal physiologic processes that occur during pregnancy implantation and processes that promote the elimination of pathogenic microbes. Recent research has demonstrated an association between this system and PTB. The purpose of this article is to present a mechanistic model of inflammation-associated PTB, which hypothesizes a relationship between the microbiome and dysregulation of the complement system. Exploring the relationships between the microbial environment and complement biomarkers may elucidate a potentially modifiable biological pathway to PTB.

The Relationship of Novel Plasma Proteins in the Early Neonatal Period With Retinopathy of Prematurity

Purpose

Retinopathy of prematurity (ROP) is a vision-threatening disease associated with abnormal retinal vascular development. Proteins from the insulin-like growth factor pathway are related to ROP. However, there is a paucity of research on the role of other proteins in ROP. The aim of this study was to identify plasma proteins related to clinically significant ROP.

Methods

We measured 1121 plasma proteins in the early neonatal period in infants at risk for ROP using an aptamer-based proteomic technology. The primary aim of the study was to compare plasma protein concentrations in infants who did (n = 12) and did not (n = 23) subsequently develop clinically significant ROP using logistic regression. As a secondary aim, we examined patterns in the proteins across categories of clinically significant, low-grade, and no ROP groups.

Results

Lower levels of 16 proteins were associated with an increased risk of clinically significant ROP. In this group, superoxide dismutase (Mn), mitochondrial (MnSOD), and chordin-like protein 1 (CRDL1) were highly ranked. Other proteins in this group included: C-C motif chemokine 14 (HCC-1), prolactin, insulin-like growth factor-binding protein 7 (IGFBP-7), and eotaxin. Higher levels of 12 proteins were associated with a higher risk for ROP. Fibroblast growth factor 19 (FGF-19) was the top-ranked protein target followed by hepatocyte growth factor-like protein (MSP), luteinizing hormone (LH), cystatin M, plasminogen, and proprotein convertase subtilisin/kexin type 9 (PCSK9). We also noted different patterns in the trend of concentrations of proteins across the clinically significant, low-grade, and no ROP groups.

Conclusions

We discovered plasma proteins with novel associations with clinically significant ROP (MnSOD, CRDL1, PCSK9), proteins with links to established ROP signaling pathways (IGFBP-7), and proteins such as MnSOD that may be a target for future therapeutic interventions.