Second- and third-trimester serum levels of placental proteins in preeclampsia and small-for-gestational age pregnancies

Low pregnancy-specific beta-1-glycoprotein is associated with nondipper hypertension and increased risk of preeclampsia in pregnant women with newly diagnosed chronic hypertension

Chronic hypertension is one of the major risk factors for preeclampsia. Pregnancy-specific beta-1-glycoprotein (PSG-1) is a protein that plays a critical role in fetomaternal immune modulation and has been shown to be closely associated with pregnancy adverse events such as preeclampsia. It is also known that PSG-1 and its source placenta are associated with many molecular pathways associated with blood pressure regulation. In addition, the nondipping pattern (NDP) of chronic hypertension has been shown to be an independent risk factor for preeclampsia. Dipper individuals experience a notable nighttime drop in blood pressure, typically around 10% or more compared to daytime levels, while nondipper individuals show a smaller nighttime blood pressure decrease, indicating potential circadian blood pressure regulation disruption. In this context, we aimed to reveal the relationship between PSG-1, NDP and preeclampsia in this study. A total of 304 pregnant women who were newly diagnosed in the first trimester and started on antihypertensive medication were included in this study. All subjects performed 24-h ambulatory blood pressure monitoring twice throughout pregnancy, the first in the 1. trimester to confirm the diagnosis of hypertension and the second between 20+0 and 21+1 gestational weeks to determine the dipper-nondipper status of hypertension. Subjects were grouped as dipper and nondipper according to blood pressure, and groups were compared in terms of PSG-1 levels. In this study, low PSG-1 levels and NDP were independently associated with preeclampsia. Findings from this study suggest that PSG-1 may play an important role in the causal relationship between NDP and preeclampsia.

Longitudinal Proteomic Analysis of Plasma across Healthy Pregnancies Reveals Indicators of Gestational Age

Longitudinal changes in the blood proteome during gestation relate to fetal development and maternal homeostasis. Charting the maternal blood proteome in normal pregnancies is critical for establishing a baseline reference when assessing complications and disease. Using mass spectrometry-based shotgun proteomics, we surveyed the maternal plasma proteome across uncomplicated pregnancies. Results indicate a significant rise in proteins that govern placentation and are vital to the development and health of the fetus. Importantly, we uncovered proteome signatures that strongly correlated with gestational age. Fold increases and correlations between the plasma concentrations of ADAM12 (ρ = 0.973), PSG1 (ρ = 0.936), and/or CSH1/2 (ρ = 0.928) with gestational age were validated with ELISA. Proteomic and validation analyses demonstrate that the maternal plasma concentration of ADAM12, either independently or in combination with either PSG1 or CSH1/2, correlates with gestational age within ±8 days throughout pregnancy. These findings suggest that the gestational age in healthy pregnancies may be determined by referencing the concentration of select plasma proteins.

Long-term observational study of renal outcome after preeclampsia: Role of soluble fms-like tyrosine kinase-1(sFlt-1)/ placental growth factor (PlGF) and endoglin

Introduction

Preeclampsia (PE) is an important complication of pregnancy that can lead to chronic kidney disease. Soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF), the sFlt-1/PlGF ratio and endoglin are biomarkers for the differential diagnosis of PE and other diseases. We aimed to explore the correlation of these biomarkers with long-term renal function, blood pressure and the urine albumin/creatinine ratio (UACR) in PE patients.

Methods

34 patients with PE were enrolled. Blood samples for sFlt-1, PlGF, endoglin and the urine albumin/creatinine ratio (UACR) were collected at the time of PE diagnosis (at 35–40 weeks’ gestational age (GA) (87.50% of cases). After delivery, the patients were followed up at three months and one year to assess blood pressure, renal function and the UACR.

Results

Thirty-four PE patients were included, and 17 completed the study. The estimated glomerular filtration rate (eGFR) decreased significantly at three months and one year after follow-up (128.20 ± 10.34 to 120.75 ± 10.166 ml/min/1.73 m² (p = 0.001) at three months and 126.71 ± 9.948 to 114.29 ± 11.274 ml/min/1.73 m² (p < 0.001) at one year). The endoglin level correlated significantly with the eGFR level during PE, but there was no correlation of any biomarker with eGFR, blood pressure, or the UACR at one year.

Conclusion

Women with PE have a reduction of eGFR at three months and one year after the diagnosis of PE. Only endoglin is correlated with eGFR antepartum; however, it is not correlated with long-term renal function, blood pressure or the UACR.

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Preeclampsia has been suggested to increase the risk of kidney problems.

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The soluble endoglin level and sFlt-1:PlGF ratio can predict early and late-onset preeclampsia.

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Analysis of angiogenic factors may be associated with long term renal function.

Sexually dimorphic patterns in maternal circulating microRNAs in pregnancies complicated by fetal growth restriction

Background

Current methods fail to accurately predict women at greatest risk of developing fetal growth restriction (FGR) or related adverse outcomes, including stillbirth. Sexual dimorphism in these adverse pregnancy outcomes is well documented as are sex-specific differences in gene and protein expression in the placenta. Circulating maternal serum microRNAs (miRNAs) offer potential as biomarkers that may also be informative of underlying pathology. We hypothesised that FGR would be associated with an altered miRNA profile and would differ depending on fetal sex.

Methods

miRNA expression profiles were assessed in maternal serum (> 36 weeks’ gestation) from women delivering a severely FGR infant (defined as an individualised birthweight centile (IBC) < 3rd) and matched control participants (AGA; IBC = 20–80th), using miRNA arrays. qPCR was performed using specific miRNA primers in an expanded cohort of patients with IBC < 5th (n = 15 males, n = 16 females/group). Maternal serum human placental lactogen (hPL) was used as a proxy to determine if serum miRNAs were related to placental dysfunction. In silico analyses were performed to predict the potential functions of altered miRNAs.

Results

Initial analyses revealed 11 miRNAs were altered in maternal serum from FGR pregnancies. In silico analyses revealed all 11 altered miRNAs were located in a network of genes that regulate placental function. Subsequent analysis demonstrated four miRNAs showed sexually dimorphic patterns. miR-28-5p was reduced in FGR pregnancies (p < 0.01) only when there was a female offspring and miR-301a-3p was only reduced in FGR pregnancies with a male fetus (p < 0.05). miR-454-3p was decreased in FGR pregnancies (p < 0.05) regardless of fetal sex but was only positively correlated to hPL when the fetus was female. Conversely, miR-29c-3p was correlated to maternal hPL only when the fetus was male. Target genes for sexually dimorphic miRNAs reveal potential functional roles in the placenta including angiogenesis, placental growth, nutrient transport and apoptosis.

Conclusions

These studies have identified sexually dimorphic patterns for miRNAs in maternal serum in FGR. These miRNAs may have potential as non-invasive biomarkers for FGR and associated placental dysfunction. Further studies to determine if these miRNAs have potential functional roles in the placenta may provide greater understanding of the pathogenesis of placental dysfunction and the differing susceptibility of male and female fetuses to adverse in utero conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00405-z.

Detection and treatment of pregnancies at high risk of fetal growth restriction (FGR) and stillbirth remains a major obstetric challenge; circulating maternal serum microRNAs (miRNAs) offer potential as novel biomarkers.

Unbiased analysis of serum miRNAs in women in late pregnancy identified a specific profile of circulating miRNAs in women with a growth-restricted infant.

Some altered miRNAs (miR-28-5p, miR-301a-3p) showed sexually dimorphic expression in FGR pregnancies and others a fetal-sex dependent association to a hormonal marker of placental dysfunction (miR-454-3p, miR-29c-3p).

miR-301a-3p and miR-28-5p could potentially be used to predict FGR specifically in pregnancies with a male or female baby, respectively, however larger cohort studies are required.

Further investigations of these miRNAs and their relationship to placental dysfunction will lead to a better understanding of the pathophysiology of FGR and why there is differing susceptibility of male and female fetuses to FGR and stillbirth.

Smoking for two- effects of tobacco consumption on placenta

Tobacco smoking is an important public health issue recognized by the world health organization as one of the most serious, preventable risk factors for developing a series of pregnancy pathologies. Maternal smoking is positively associated with intrauterine growth restriction (IUGR) and gestational diabetes (GDM), but negatively associated with preeclampsia (PE). In this review, we examine epidemiological, clinical and laboratory studies of smoking effects on immunoregulation during pregnancy, trophoblast function, and placental vasculature development and metabolism. We aim to identify effects of tobacco smoke components on specific placental compartments or cells, which may contribute to the understanding of the influences of maternal smoking on placenta function in normal and pathological pregnancies. Data corroborates that in any trimester, smoking is unsafe for pregnancy and that its detrimental effects outweigh questionable benefits. The effects of maternal smoking on the maternal immune regulation throughout pregnancy and the impact of different tobacco products on fetal growth have not yet been fully understood. Smoking cessation rather than treatment with replacement therapies is recommended for future mothers because also single components of tobacco and its smoke may have detrimental effects on placental function.

Circulating EGFL7 distinguishes between IUGR and PE: an observational case-control study

Isolated intrauterine growth restriction (IUGR) and preeclampsia (PE) share common placental pathogenesis. Differently from IUGR, PE is a systemic disorder which may also affect liver and brain. Early diagnosis of these conditions may optimize maternal and fetal management. Aim of this study was to assess whether Epidermal Growth Factor-Like domain 7 (EGFL7) dosage in maternal blood discriminates between isolated IUGR and PE. A total of 116 women were enrolled in this case–control study: 12 non-pregnant women, 34 healthy pregnant women, 34 women presenting with isolated IUGR and 36 presenting with PE. Levels of circulating EGFL7 and other known pro- and anti-angiogenic factors were measured by ELISA at different gestational ages (GA). Between 22–25 weeks of gestation, EGFL7 levels in early-onset PE (e-PE) plasma samples were significantly higher than those measured in controls or isolated IUGR samples (69.86 ± 6.17 vs. 19.8 ± 2.5 or 18.8 ± 2.8 µg/ml, respectively). Between 26–34 weeks, EGFL7 levels remained significantly higher in e-PE compared to IUGR. At term, circulating and placental EGFL7 levels were comparable between IUGR and late-onset PE (l-PE). In contrast, circulating levels of PlGF were decreased in both IUGR- and PE- complicated pregnancies, while levels of both sFLT-1 and sENDOGLIN were increased in both conditions. In conclusion, EGFL7 significantly discriminates between isolated IUGR and PE.

Unravelling the potential of angiogenic factors for the early prediction of preeclampsia

Preeclampsia is a multisystem, multiorgan hypertensive disorder of pregnancy responsible for maternal and perinatal morbidity and mortality in low- and middle-income countries. The classic diagnostic features hold less specificity for preeclampsia and its associated adverse outcomes, suggesting a need for specific and reliable biomarkers for the early prediction of preeclampsia. The imbalance of pro- and antiangiogenic circulatory factors contributes to the pathophysiology of preeclampsia. Several studies have examined the profile of angiogenic factors in preeclampsia to search for a biomarker that will improve the diagnostic ability of preeclampsia and associated adverse outcomes. This may help in more efficient patient management and the reduction of associated health care costs. This article reviews the findings from previous studies published to date on angiogenic factors and suggests a need to apply a multivariable model from the beginning of pregnancy and continuing throughout gestation for the early and specific prediction of preeclampsia.

Pregnancy-specific glycoprotein 9 acts as both a transcriptional target and a regulator of the canonical TGF-β/Smad signaling to drive breast cancer progression

Pregnancy-specific glycoprotein 9 (PSG9) is a placental glycoprotein essential for the maintenance of normal gestation in mammals. Bioinformatics analysis of multiple publicly available datasets revealed aberrant PSG9 expression in breast tumors, but its functional and mechanistic role in breast cancer remains unexplored. Here, we report that PSG9 expression levels were elevated in tumor tissues and plasma specimens from breast cancer patients, and were associated with poor prognosis. Gain- or loss-of-function studies demonstrated that PSG9 promoted breast cancer cell proliferation, migration, and invasionin vitro, and enhanced tumor growth and lung colonization in vivo. Mechanistically, transforming growth factor-β1 (TGF-β1) transcriptionally activated PSG9 expression through enhancing the enrichment of Smad3 and Smad4 onto PSG9 promoter regions containing two putative Smad-binding elements (SBEs). Mutation of both SBEs in the PSG9 promoter, or knockdown of TGF-β receptor 1 (TGFBR1), TGFBR2, Smad3, or Smad4 impaired the ability of TGF-β1 to induce PSG9 expression. Consequently, PSG9 contributed to TGF-β1-induced epithelial-mesenchymal transition (EMT) and breast cancer cell migration and invasion. Moreover, PSG9 enhanced the stability of Smad2, Smad3, and Smad4 proteins by blocking their proteasomal degradation, and regulated the expression of TGF-β1 target genes involved in EMT and breast cancer progression, thus further amplifying the canonical TGF-β/Smad signaling in breast cancer cells. Collectively, these findings establish PSG9 as a novel player in breast cancer progressionvia hijacking the canonical TGF-β/Smad signaling, and identify PSG9 as a potential plasma biomarker for the early detection of breast cancer.

Evaluation of Maternal Reproductive Outcomes and Biochemical Analysis from Wistar Audiogenic Rats (WAR) and Repercussions in Their Offspring

The objective of the present study was to evaluate maternal reproductive performance, body weight, and frequency of external and internal anomalies of newborns of Wistar Audiogenic Rat (WAR) females as compared with Wistar rats. The adult WAR and Wistar rats were mated within their respective strains. After confirming the pregnancy, the body weights were weekly evaluated. On day 21 of pregnancy, the female rats were anesthetized and sacrificed to evaluate the maternal reproductive outcomes and biochemical profile, newborn weight, and external and internal anomalies. The WAR strain gained less weight during the pregnancy and presented hyperproteinemia, hypertriglyceridemia, and embryonic losses concerning Wistar rats, suggesting an inadequate intrauterine condition for embryonic development and fetal viability. WAR also presented a higher percentage of newborns classified as small for gestational age related to intrauterine growth restriction, which was confirmed by the lower number of ossification centers. There was a higher percentage of skeletal anomalies compared with fetuses of the Wistar dams, confirming their greater susceptibility during the formation and development of their skeletal system. Thus, the WAR presents physiological alterations compromising the viability of their embryos and fetuses, leading to impaired development of the newborns.

Interaction of Pregnancy-Specific Glycoprotein 1 With Integrin Α5β1 Is a Modulator of Extravillous Trophoblast Functions

Human pregnancy-specific glycoproteins (PSGs) serve immunomodulatory and pro-angiogenic functions during pregnancy and are mainly expressed by syncytiotrophoblast cells. While PSG mRNA expression in extravillous trophoblasts (EVTs) was reported, the proteins were not previously detected. By immunohistochemistry and immunoblotting, we show that PSGs are expressed by invasive EVTs and co-localize with integrin 5. In addition, we determined that native and recombinant PSG1, the most highly expressed member of the family, binds to 51 and induces the formation of focal adhesion structures resulting in adhesion of primary EVTs and EVT-like cell lines under 21% oxygen and 1% oxygen conditions. Furthermore, we found that PSG1 can simultaneously bind to heparan sulfate in the extracellular matrix and to 51 on the cell membrane. Wound healing assays and single-cell movement tracking showed that immobilized PSG1 enhances EVT migration. Although PSG1 did not affect EVT invasion in the in vitro assays employed, we found that the serum PSG1 concentration is lower in African-American women diagnosed with early-onset and late-onset preeclampsia, a pregnancy pathology characterized by shallow trophoblast invasion, than in their respective healthy controls only when the fetus was a male; therefore, the reduced expression of this molecule should be considered in the context of preeclampsia as a potential therapy.

Biochemical tests of placental function versus ultrasound assessment of fetal size for stillbirth and small-for-gestational-age infants

BACKGROUND

Stillbirth affects 2.6 million pregnancies worldwide each year. Whilst the majority of cases occur in low- and middle-income countries, stillbirth remains an important clinical issue for high-income countries (HICs) - with both the UK and the USA reporting rates above the mean for HICs. In HICs, the most frequently reported association with stillbirth is placental dysfunction. Placental dysfunction may be evident clinically as fetal growth restriction (FGR) and small-for-dates infants. It can be caused by placental abruption or hypertensive disorders of pregnancy and many other disorders and factorsPlacental abnormalities are noted in 11% to 65% of stillbirths. Identification of FGA is difficult in utero. Small-for-gestational age (SGA), as assessed after birth, is the most commonly used surrogate measure for this outcome. The degree of SGA is associated with the likelihood of FGR; 30% of infants with a birthweight < 10th centile are thought to be FGR, while 70% of infants with a birthweight < 3rd centile are thought to be FGR. Critically, SGA is the most significant antenatal risk factor for a stillborn infant. Correct identification of SGA infants is associated with a reduction in the perinatal mortality rate. However, currently used tests, such as measurement of symphysis-fundal height, have a low reported sensitivity and specificity for the identification of SGA infants.

OBJECTIVES

The primary objective was to assess and compare the diagnostic accuracy of ultrasound assessment of fetal growth by estimated fetal weight (EFW) and placental biomarkers alone and in any combination used after 24 weeks of pregnancy in the identification of placental dysfunction as evidenced by either stillbirth, or birth of a SGA infant. Secondary objectives were to investigate the effect of clinical and methodological factors on test performance.

SEARCH METHODS

We developed full search strategies with no language or date restrictions. The following sources were searched: MEDLINE, MEDLINE In Process and Embase via Ovid, Cochrane (Wiley) CENTRAL, Science Citation Index (Web of Science), CINAHL (EBSCO) with search strategies adapted for each database as required; ISRCTN Registry, UK Clinical Trials Gateway, WHO International Clinical Trials Portal and ClinicalTrials.gov for ongoing studies; specialist abstract and conference proceeding resources (British Library's ZETOC and Web of Science Conference Proceedings Citation Index). Search last conducted in Ocober 2016.

SELECTION CRITERIA

We included studies of pregnant women of any age with a gestation of at least 24 weeks if relevant outcomes of pregnancy (live birth/stillbirth; SGA infant) were assessed. Studies were included irrespective of whether pregnant women were deemed to be low or high risk for complications or were of mixed populations (low and high risk). Pregnancies complicated by fetal abnormalities and multi-fetal pregnancies were excluded as they have a higher risk of stillbirth from non-placental causes. With regard to biochemical tests, we included assays performed using any technique and at any threshold used to determine test positivity.

DATA COLLECTION AND ANALYSIS

We extracted the numbers of true positive, false positive, false negative, and true negative test results from each study. We assessed risk of bias and applicability using the QUADAS-2 tool. Meta-analyses were performed using the hierarchical summary ROC model to estimate and compare test accuracy.

MAIN RESULTS

We included 91 studies that evaluated seven tests - blood tests for human placental lactogen (hPL), oestriol, placental growth factor (PlGF) and uric acid, ultrasound EFW and placental grading and urinary oestriol - in a total of 175,426 pregnant women, in which 15,471 pregnancies ended in the birth of a small baby and 740 pregnancies which ended in stillbirth. The quality of included studies was variable with most domains at low risk of bias although 59% of studies were deemed to be of unclear risk of bias for the reference standard domain. Fifty-three per cent of studies were of high concern for applicability due to inclusion of only high- or low-risk women.Using all available data for SGA (86 studies; 159,490 pregnancies involving 15,471 SGA infants), there was evidence of a difference in accuracy (P < 0.0001) between the seven tests for detecting pregnancies that are SGA at birth. Ultrasound EFW was the most accurate test for detecting SGA at birth with a diagnostic odds ratio (DOR) of 21.3 (95% CI 13.1 to 34.6); hPL was the most accurate biochemical test with a DOR of 4.78 (95% CI 3.21 to 7.13). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.88 and median prevalence of 19%, EFW, hPL, oestriol, urinary oestriol, uric acid, PlGF and placental grading will miss 50 (95% CI 32 to 68), 116 (97 to 133), 124 (108 to 137), 127 (95 to 152), 139 (118 to 154), 144 (118 to 161), and 144 (122 to 161) SGA infants, respectively. For the detection of pregnancies ending in stillbirth (21 studies; 100,687 pregnancies involving 740 stillbirths), in an indirect comparison of the four biochemical tests, PlGF was the most accurate test with a DOR of 49.2 (95% CI 12.7 to 191). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.78 and median prevalence of 1.7%, PlGF, hPL, urinary oestriol and uric acid will miss 2 (95% CI 0 to 4), 4 (2 to 8), 6 (6 to 7) and 8 (3 to 13) stillbirths, respectively. No studies assessed the accuracy of ultrasound EFW for detection of pregnancy ending in stillbirth.

AUTHORS' CONCLUSIONS

Biochemical markers of placental dysfunction used alone have insufficient accuracy to identify pregnancies ending in SGA or stillbirth. Studies combining U and placental biomarkers are needed to determine whether this approach improves diagnostic accuracy over the use of ultrasound estimation of fetal size or biochemical markers of placental dysfunction used alone. Many of the studies included in this review were carried out between 1974 and 2016. Studies of placental substances were mostly carried out before 1991 and after 2013; earlier studies may not reflect developments in test technology.

Integrated Systems Biology Approach Identifies Novel Maternal and Placental Pathways of Preeclampsia

Preeclampsia is a disease of the mother, fetus, and placenta, and the gaps in our understanding of the complex interactions among their respective disease pathways preclude successful treatment and prevention. The placenta has a key role in the pathogenesis of the terminal pathway characterized by exaggerated maternal systemic inflammation, generalized endothelial damage, hypertension, and proteinuria. This sine qua non of preeclampsia may be triggered by distinct underlying mechanisms that occur at early stages of pregnancy and induce different phenotypes. To gain insights into these molecular pathways, we employed a systems biology approach and integrated different "omics," clinical, placental, and functional data from patients with distinct phenotypes of preeclampsia. First trimester maternal blood proteomics uncovered an altered abundance of proteins of the renin-angiotensin and immune systems, complement, and coagulation cascades in patients with term or preterm preeclampsia. Moreover, first trimester maternal blood from preterm preeclamptic patients in vitro dysregulated trophoblastic gene expression. Placental transcriptomics of women with preterm preeclampsia identified distinct gene modules associated with maternal or fetal disease. Placental "virtual" liquid biopsy showed that the dysregulation of these disease gene modules originates during the first trimester. In vitro experiments on hub transcription factors of these gene modules demonstrated that DNA hypermethylation in the regulatory region of ZNF554 leads to gene down-regulation and impaired trophoblast invasion, while BCL6 and ARNT2 up-regulation sensitizes the trophoblast to ischemia, hallmarks of preterm preeclampsia. In summary, our data suggest that there are distinct maternal and placental disease pathways, and their interaction influences the clinical presentation of preeclampsia. The activation of maternal disease pathways can be detected in all phenotypes of preeclampsia earlier and upstream of placental dysfunction, not only downstream as described before, and distinct placental disease pathways are superimposed on these maternal pathways. This is a paradigm shift, which, in agreement with epidemiological studies, warrants for the central pathologic role of preexisting maternal diseases or perturbed maternal-fetal-placental immune interactions in preeclampsia. The description of these novel pathways in the "molecular phase" of preeclampsia and the identification of their hub molecules may enable timely molecular characterization of patients with distinct preeclampsia phenotypes.

Clinical Presentation of Preeclampsia and the Diagnostic Value of Proteins and Their Methylation Products as Biomarkers in Pregnant Women with Preeclampsia and Their Newborns

Preeclampsia (PE) is a disorder which affects 1-10% of pregnant women worldwide. It is characterised by hypertension and proteinuria in the later stages of gestation and can lead to maternal and perinatal morbidity and mortality. Other than the delivery of the foetus and the removal of the placenta, to date there are no therapeutic approaches to treat or prevent PE. It is thus only possible to reduce PE-related mortality through early detection, careful monitoring, and treatment of the symptoms. For these reasons the search for noninvasive, blood-borne, or urinary biochemical markers that could be used for the screening, presymptomatic diagnosis, and prediction of the development of PE is of great urgency. So far, a number of biomarkers have been proposed for predicting PE, based on pathophysiological observations, but these have mostly proven to be unreliable and inconsistent between different studies. The clinical presentation of PE and data gathered for the biochemical markers placental growth factor (PlGF), soluble Feline McDonough Sarcoma- (fms-) like tyrosine kinase-1 (sFlt-1), asymmetric dimethylarginine (ADMA), and methyl-lysine is being reviewed with the aim of providing both a clinical and biochemical understanding of how these biomarkers might assist in the diagnosis of PE or indicate its severity.

Placental growth factor as an indicator of fetal growth restriction in late-onset small-for-gestational age pregnancies

BACKGROUND

At-risk small-for-gestational age (SGA) pregnancies in New Zealand are identified using Doppler ultrasound; fetuses with Doppler abnormalities are considered growth restricted (FGR). Low maternal placental growth factor (PlGF) has also been associated with late-onset FGR.

AIMS

To investigate whether low PlGF at diagnosis of late-onset SGA identifies the same fetuses classified FGR by detailed Doppler studies, and the association between low PlGF and adverse pregnancy outcomes.

METHODS

Among an historical database of normotensive suspected SGA pregnancies (fetal abdominal circumference <10th percentile) ≥32 weeks gestation, the ability of low PlGF (<5th percentile) to identify FGR infants was investigated. 'Initial FGR' was an abnormal umbilical artery resistance index (RI) or estimated fetal weight <3rd customised centile. 'Secondary FGR' was abnormal internal carotid RI, cerebro-placental ratio and/or mean uterine artery RI. Development of hypertensive disease and adverse perinatal outcomes were compared by PlGF status.

RESULTS

Of 136 SGA pregnancies, 56 (41.1%) had initial FGR. Of the remaining, 20 (25.0%) had secondary FGR, 17 (21.3%) low PlGF. The sensitivity of low PlGF identifying secondary FGR was 0.30 (95% CI 0.14-0.50), specificity 0.83 (0.70-0.92), positive predictive value 0.47 (0.23-0.72) and negative predictive value 0.70 (0.57-0.81). Overall, low PlGF occurred in 44/136 (32.4%) pregnancies and was associated with gestational hypertensive disease (63.6% vs 15.2%, P < 0.01), adverse perinatal outcome (34.1% vs 15.2%, P = 0.01) and very low birthweight (customised centile 2.2 vs 6.8, P < 0.01).

CONCLUSIONS

At diagnosis of late-onset SGA, low PlGF was poor at identifying Doppler-defined FGR. Low PlGF identified pregnancies at risk of hypertensive disease, adverse perinatal outcome and very low birthweight.

Systematic review of maternal Placental Growth Factor levels in late pregnancy as a predictor of adverse intrapartum and perinatal outcomes

AIM

This systematic review evaluates the utility of maternal Placental Growth Factor (PlGF) when measured in late pregnancy (>20 weeks) as a predictor of adverse obstetric and perinatal outcomes.

METHODS

Pubmed and Embase were searched using the term "placental growth factor" in combination with relevant perinatal outcomes. Studies were included if they measured PlGF levels in pregnant women after 20 + 0 weeks gestation and reported relevant adverse obstetric or perinatal outcomes related to placental insufficiency (excluding pre-eclampsia).

RESULTS

Twenty-six studies were eligible for inclusion with 21 studies investigating the relationship between PlGF and small for gestational age (SGA) and 7 studies investigating PlGF for the prediction of other adverse perinatal outcomes. In all studies, maternal PlGF levels were significantly lower in the SGA group compared to controls. Other outcomes investigated included caesarean section (CS) for fetal compromise, low Apgar score, neonatal intensive care unit (NICU) admission, neonatal acidosis, stillbirth, and intrapartum fetal compromise. The results generally showed a significant association between low PlGF levels and CS for fetal compromise, NICU admission and stillbirth.

CONCLUSION

Low maternal PlGF levels in late pregnancy are strongly associated with SGA. Findings across studies were variable in relation to PlGF and the prediction of other adverse intrapartum and perinatal outcomes, however there was a consistent association between low PlGF levels and CS for fetal compromise, NICU admission and stillbirth. This review suggests that the use of PlGF for the prediction of adverse outcomes is promising. Its predictive value may potentially be enhanced if used in combination with other biomarkers or biophysical measures of fetal well-being.

Screening for fetal growth restriction using fetal biometry combined with maternal biomarkers

Fetal growth restriction is a major determinant of perinatal morbidity and mortality. Screening for fetal growth restriction is a key element of prenatal care but it is recognized to be problematic. Screening using clinical risk assessment and targeting ultrasound to high-risk women is the standard of care in the United States and United Kingdom, but the approach is known to have low sensitivity. Systematic reviews of randomized controlled trials do not demonstrate any benefit from universal ultrasound screening for fetal growth restriction in the third trimester, but the evidence base is not strong. Implementation of universal ultrasound screening in low-risk women in France failed to reduce the risk of complications among small-for-gestational-age infants but did appear to cause iatrogenic harm to false positives. One strategy to making progress is to improve screening by developing more sensitive and specific tests with the key goal of differentiating between healthy small fetuses and those that are small through fetal growth restriction. As abnormal placentation is thought to be the major cause of fetal growth restriction, one approach is to combine fetal biometry with an indicator of placental dysfunction. In the past, these indicators were generally ultrasonic measurements, such as Doppler flow velocimetry of the uteroplacental circulation. However, another promising approach is to combine ultrasonic suspicion of small-for-gestational-age infant with a blood test indicating placental dysfunction. Thus far, much of the research on maternal serum biomarkers for fetal growth restriction has involved the secondary analysis of tests performed for other indications, such as fetal aneuploidies. An exemplar of this is pregnancy-associated plasma protein A. This blood test is performed primarily to assess the risk of Down syndrome, but women with low first-trimester levels are now serially scanned in later pregnancy due to associations with placental causes of stillbirth, including fetal growth restriction. The development of "omic" technologies presents a huge opportunity to identify novel biomarkers for fetal growth restriction. The hope is that when such markers are measured alongside ultrasonic fetal biometry, the combination would have strong predictive power for fetal growth restriction and its related complications. However, a series of important methodological considerations in assessing the diagnostic effectiveness of new tests will have to be addressed. The challenge thereafter will be to identify novel disease-modifying interventions, which are the essential partner to an effective screening test to achieve clinically effective population-based screening.

Peripheral blood cell microRNA quantification during the first trimester predicts preeclampsia: Proof of concept

Objective

We investigated the capacity of microRNAs isolated from peripheral blood buffy coat collected late during the first trimester to predict preeclampsia.

Study design

The cohort study comprised 48 pregnant women with the following pregnancy outcomes: 8 preeclampsia and 40 with normal delivery outcomes. Quantitative rtPCR was performed on a panel of 30 microRNAs from buffy coat samples drawn at a mean of 12.7±0.5 weeks gestation. MicroRNA Risk Scores were calculated and AUC-ROC calculations derived.

Results

The AUC-ROC for preeclampsia risk was 0.91 (p<0.0001). When women with normal delivery and high-risk background (those with SLE/APS, chronic hypertension and/or Type 2 Diabetes) were compared to women who developed preeclampsia but with a normal risk background (without these mentioned risk factors), preeclampsia was still predicted with an AUC-ROC of 0.92 (p<0.0001).

Conclusion

MicroRNA quantification of peripheral immune cell microRNA provides sensitive and specific prediction of preeclampsia in the first trimester of pregnant women. With this study, we extend the range during which disorders of the placental bed may be predicted from early to the end of the first trimester. This study confirms that buffy coat may be used as a sample preparation.

Second-trimester maternal serum markers in the prediction of preeclampsia

AIM

To determine whether late second-trimester maternal serum biomarkers are useful for the prediction of preeclampsia during the third trimester, a case-control study including 33 preeclamptic and 71 healthy pregnancies was conducted. Maternal serum concentrations of placental protein 13 (PP13), pregnancy-associated plasma protein (PAPP-A), pentraxin3 (PTX3), soluble FMS-like tyrosine kinase-1 (sFlt-1), myostatin and follistatin-like-3 (FSLT-3) were measured at 24-28 weeks' gestation. All the concentrations of these markers were compared between the preeclamptic and control groups. Receiver operating characteristic (ROC) curve analysis was applied to assess sensitivity and specificity of serum markers with significant difference.

RESULTS

The levels of PP13 and sFlt-1 were significantly increased and FSLT3 was significantly decreased in patients with preeclampsia. However, the concentration of PAPPA, PTX3 and myostatin did not differ significantly. In screening for preeclampsia during the third trimester by PP13, sFlt-1 and FSLT3, the detection rate was 61.3%, 48.1% and 39.1%, respectively, at 80% specificity, and the detection rate increased to 69.8% by combination of these three markers.

CONCLUSION

Maternal serum levels of PP13, sFlt-1 and FSLT3 play an important role in predicting late-onset preeclampsia, and the combination of these three markers significantly increases the detection rate for prediction.

Mild anemia during pregnancy upregulates placental vascularity development

The connection between maternal hematological status and pregnancy outcome has been shown by many independent researchers. Attention was initially focused on the adverse effects of moderate and severe anemia. Interestingly, some studies revealed that mild anemia was associated with optimal fetal development and was not affecting pregnancy outcome. The explanation for this phenomenon became a target for scientists. Hemodilution, physiologic anemia and relative decrease in hemoglobin concentration are the changes observed during pregnancy but they do not explain the reasons for the positive influence of mild anemia on a fetomaternal unit. It is hypothesized that hemodilution facilitates placental perfusion because blood viscosity is reduced. Subsequently, it may lead to a decline in hemoglobin concentration. Anemia from its definition implies decreased oxygen carrying capacity of the blood and can result in hypoxemia and even hypoxia, which is a common factor inducing new blood vessels formation. Therefore, we raised the hypothesis that the lowered hemoglobin concentration during pregnancy may upregulate vascular growth factor receptors expression such as VEGFR-1 (Flt-1) and VEGFR-2 (FLK-1/KDR). Consecutively, increased fetoplacental vasculogenesis and angiogenesis provide further expansion of vascular network development, better placental perfusion and hence neither fetus nor the mother are affected.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

Maternal serum PAPP-A and free β-hCG at 12, 22 and 32 weeks' gestation in screening for pre-eclampsia

OBJECTIVE

To examine the distribution of maternal serum pregnancy-associated plasma protein-A (PAPP-A) and free β-human chorionic gonadotropin (β-hCG) at 12, 22 and 32 weeks' gestation in singleton pregnancies which develop pre-eclampsia (PE) and examine the performance of these biomarkers in screening for PE.

METHODS

Serum PAPP-A and free β-hCG were measured in 94 989 cases at 11-13 weeks, 7597 at 19-24 weeks and 8088 at 30-34 weeks' gestation. Bayes' theorem was used to combine the a-priori risk from maternal characteristics and medical history with PAPP-A and free β-hCG. The empirical and model-based performance of screening for preterm PE requiring delivery < 37 weeks' gestation and term PE with delivery ≥ 37 weeks was estimated.

RESULTS

Combined screening with maternal factors and serum PAPP-A at 11-13 and 30-34 weeks and with maternal factors and serum free β-hCG at 19-24 and 30-34 weeks improved the prediction provided by maternal factors alone for preterm PE. The detection rate, at a 10% false-positive rate, for preterm PE by screening with maternal factors was about 45% which improved to 51% and 53% by combined screening with PAPP-A at 11-13 weeks and 30-34 weeks, respectively, and 55% and 54% by combined screening with free β-hCG at 19-24 weeks and 30-34 weeks, respectively. Measurement of serum PAPP-A and free β-hCG was not useful in the prediction of term PE.

CONCLUSIONS

Measurement of serum PAPP-A and free β-hCG could improve the prediction of preterm PE provided by maternal characteristics and medical history alone. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Tpbpa mediated deletion of Tfap2c leads to deregulation of MAPK, P21, AKT and subsequent placental growth arrest

Loss of Tfap2c leads to developmental defects in the extra-embryonic compartment with embryonic lethality at E7.5. To investigate requirement of Tfap2c in later placental development, deletion of Tfap2c was induced throughout extra-embryonic ectoderm at E6.5 leading to severe placental abnormalities caused by reduced trophoblast population resulting in embryonic retardation by E8.5. Deletion of Tfap2c in Tpbpa+ progenitors at E8.5 results in growth arrest of junctional zone. TFAP2C regulates its target genes p21/Cdkn1a and Dusp6, involved in repression of MAPK signaling. Loss of TFAP2C reduces activation of ERK1/2 in the placenta. Downregulation of Akt and reduced activation of pAKT in the mutant placenta are accompanied by impaired glycogen synthesis. Loss of Tfap2c led to upregulation of imprinted gene H19 and downregulation of Tex19.1 and Ascl2. The placental insufficiency post E16.5 causes fetal growth restriction with 19% lighter mutant pups. TFAP2C knockdown in human trophoblast choriocarcinoma JAr cells inhibited MAPK and AKT signaling. Thus, we present a model where Tfap2c in trophoblasts controls proliferation by repressing P21 and activating MAPK pathway and further supporting differentiation of glycogen cells via activating Akt pathway.

Combined Screening for Early Detection of Pre-Eclampsia

Although the precise pathophysiology of pre-eclampsia remains unknown, this condition continues to be a major cause of maternal and fetal mortality. Early prediction of pre-eclampsia would allow for timely initiation of preventive therapy. A combination of biophysical and biochemical markers are superior to other tests for early prediction of the development of pre-eclampsia. Apart from the use of parameters in first-trimester aneuploidy screening, cell-free fetal DNA quantification is emerging as a promising marker for prediction of pre-eclampsia. This article reviews the current research of the most important strategies for prediction of pre-eclampsia, including the use of maternal risk factors, mean maternal arterial pressure, ultrasound parameters, and biomarkers.

Serum pregnancy-associated plasma protein-A in the three trimesters of pregnancy: effects of maternal characteristics and medical history

OBJECTIVE

To define the contribution of maternal variables which influence the measured level of maternal serum pregnancy-associated plasma protein-A (PAPP-A) in screening for pregnancy complications.

METHODS

Maternal characteristics and medical history were recorded and serum PAPP-A was measured in women with a singleton pregnancy attending for three routine hospital visits at 11 + 0 to 13 + 6, 19 + 0 to 24 + 6 and 30 + 0 to 34 + 6 weeks' gestation. For pregnancies delivering phenotypically normal live births or stillbirths ≥ 24 weeks' gestation, variables from maternal demographic characteristics and medical history that are important in the prediction of PAPP-A were determined from a linear mixed-effects multiple regression.

RESULTS

Serum PAPP-A was measured in 94,966 cases in the first trimester, 7785 in the second trimester and 8286 in the third trimester. Significant independent contributions to serum PAPP-A were provided by gestational age, maternal weight, height, racial origin, cigarette smoking, diabetes mellitus, method of conception, previous pregnancy with or without pre-eclampsia (PE) and birth-weight Z-score of the neonate in the previous pregnancy. The effects of some variables were similar and those for others differed in the three different trimesters. Random-effects multiple regression analysis was used to define the contribution of maternal variables that influence the measured level of serum PAPP-A and express the values as multiples of the median (MoMs). The model was shown to provide an adequate fit of MoM values for all covariates, both in pregnancies that developed PE and in those without this pregnancy complication.

CONCLUSIONS

A model was fitted to express the measured serum PAPP-A across the three trimesters of pregnancy as MoMs, after adjusting for variables from maternal characteristics and medical history that affect this measurement.

Early prediction of preeclampsia

Effective screening for the development of early onset preeclampsia (PE) can be provided in the first-trimester of pregnancy. Screening by a combination of maternal risk factors, uterine artery Doppler, mean arterial pressure, maternal serum pregnancy-associated plasma protein-A, and placental growth factor can identify about 95% of cases of early onset PE for a false-positive rate of 10%.

Maternal serum placental growth factor isoforms 1 and 2 at 11-13, 20-24 and 30-34 weeks' gestation in late-onset pre-eclampsia and small for gestational age neonates

OBJECTIVE

To compare the maternal serum concentrations of placental growth factor (PlGF)-1 and PlGF-2 in the first, second and third trimesters in normal pregnancies and in those complicated by pre-eclampsia (PE) or the delivery of small for gestational age (SGA) neonates after 37 weeks.

METHODS

Serum PlGF-1 and PlGF-2 were measured at 11-13, 20-24 and 30-34 weeks' gestation in 50 cases of PE, 99 cases of SGA and 298 controls. The values of PlGF-1 and PlGF-2 at 11-13 weeks were expressed as multiples of the median (MoM) after adjustment for maternal characteristics. The distributions of PlGF-1 and PlGF-2 in cases and controls at 20-24 and 30-34 weeks were converted to MoM of the values at 11-13 weeks and compared.

RESULTS

Serum PlGF-1 and PlGF-2 levels were highly correlated and both increased with gestational age. At 30-34 weeks, the median MoM values for PlGF-1 and PlGF-2 in the late PE (4.2 and 4.3) and late SGA (7.2 and 6.0) groups were significantly lower than in the controls (12.8 and 9.9). Combining the two isoforms did not improve the prediction of late PE and late SGA provided by PlGF-1 alone.

CONCLUSIONS

The performances of serum PlGF-1 and PlGF-2 in the prediction of late PE and late SGA are similar.

First-trimester levels of pregnancy-associated plasma protein A2 (PAPP-A2) in the maternal circulation are elevated in pregnancies that subsequently develop preeclampsia

Recent studies have consistently found pregnancy-associated plasma protein A2 (PAPP-A2) to be upregulated in preeclamptic placentae at term. We tested whether first-trimester circulating PAPP-A2 levels differed between complicated and uncomplicated pregnancies. We measured maternal PAPP-A2 levels at 10 to 14 weeks of gestational age in 17 pregnancies resulting in small-for-gestational-age (SGA) infants, 6 which developed preeclampsia (PE), 1 which developed PE and resulted in an SGA infant, and 37 gestational age-matched controls. The concentration of the PAPP-A2 isoform corresponding to the full-length protein was significantly higher in pregnancies that developed PE (35 ng/mL) compared with those that did not (23 ng/mL; P < .044). In contrast, we found no difference in PAPP-A2 levels between pregnancies that did or did not result in an SGA infant. The upregulation of PAPP-A2 that has previously been observed in PE at term appears to begin early in pregnancy, well before the symptoms develop.

Emerging new biomarkers of preeclampsia

Preeclampsia continues to plague some of the most vulnerable women and fetuses. It is surprisingly prevalent in developing and developed nations. According to the World Health Organization, hypertension during pregnancy is a leading cause of maternal mortality in industrialized countries at 16% and up to 25% in developing countries. As the pathogenesis of this disease is being unraveled, we are afforded new opportunities to develop novel biomarkers for early identification and prevention of disease. The angiogenic markers including soluble fms-like tyrosine kinase 1, placental growth factor, and soluble endoglin have demonstrated to be the most promising, perhaps in conjunction with traditional markers such as plasma protein-13 and uterine artery Doppler studies. There is also increasing evidence that the podocyte is shed during the course of preeclampsia, which may be useful for diagnosis. Systems biology approaches to biomarker discovery such as proteomics and metabolomics are also gaining more attention and will most certainly open new avenues of research. In this review, we present the best studied biomarkers of preeclampsia to date.

The genome-defence gene Tex19.1 suppresses LINE-1 retrotransposons in the placenta and prevents intra-uterine growth retardation in mice

DNA methylation plays an important role in suppressing retrotransposon activity in mammalian genomes, yet there are stages of mammalian development where global hypomethylation puts the genome at risk of retrotransposition-mediated genetic instability. Hypomethylated primordial germ cells appear to limit this risk by expressing a cohort of retrotransposon-suppressing genome-defence genes whose silencing depends on promoter DNA methylation. Here, we investigate whether similar mechanisms operate in hypomethylated trophectoderm-derived components of the mammalian placenta to couple expression of genome-defence genes to the potential for retrotransposon activity. We show that the hypomethylated state of the mouse placenta results in activation of only one of the hypomethylation-sensitive germline genome-defence genes: Tex19.1. Tex19.1 appears to play an important role in placenta function as Tex19.1(-/-) mouse embryos exhibit intra-uterine growth retardation and have small placentas due to a reduction in the number of spongiotrophoblast, glycogen trophoblast and sinusoidal trophoblast giant cells. Furthermore, we show that retrotransposon mRNAs are derepressed in Tex19.1(-/-) placentas and that protein encoded by the LINE-1 retrotransposon is upregulated in hypomethylated trophectoderm-derived cells that normally express Tex19.1. This study suggests that post-transcriptional genome-defence mechanisms are operating in the placenta to protect the hypomethylated cells in this tissue from retrotransposons and suggests that imbalances between retrotransposon activity and genome-defence mechanisms could contribute to placenta dysfunction and disease.

Can maternal serum placental growth factor estimation in early second trimester predict the occurrence of early onset preeclampsia and/or early onset intrauterine growth restriction? A prospective cohort study

AIM

To determine whether maternal serum placental growth factor (PlGF) estimation in early second trimester (20-22 weeks of gestation) can predict the occurrence of early onset preeclampsia and/or early onset intrauterine growth restriction (IUGR).

MATERIAL AND METHODS

A prospective cohort study was conducted on 722 women with singleton pregnancies, screened from the antenatal clinic, and serum PlGF levels were estimated at 20-22 weeks of gestation. A cut-off value of <155 pg/mL for serum PlGF was determined by receiver operating characteristic (ROC) curve analysis for identifying pregnant women at risk of developing early onset preeclampsia and/or early onset IUGR. Preeclampsia and IUGR were classified as early onset when diagnosed by 32 weeks of gestation. Univariate logistic regression analysis was used to analyze the association between serum PlGF level <155 pg/mL and the two outcome measures (i.e. early onset preeclampsia and early onset IUGR) and odds ratio (OR) was computed. P-value < 0.05 was considered statistically significant.

RESULTS

Maternal serum PlGF level <155 pg/mL at 20-22 weeks of gestation had a strong association with early onset preeclampsia (OR 8.35; 95% CI 1.79-18.94; P = 0.007) and with early onset IUGR (OR 10.73; 95% CI 4.08-20.23; P = 0.000). The sensitivity of serum PlGF < 155 pg/mL for predicting early onset preeclampsia and early onset IUGR were 82 and 84, respectively.

CONCLUSION

Maternal serum PlGF level estimation in early second trimester (20-22 weeks of gestation) may be useful in predicting the occurrence of early onset preeclampsia and/or early onset IUGR.

The obstetric syndromes: clinical relevance of placental hormones

Preterm delivery, preeclampsia and intrauterine growth restriction are the major diseases of pregnancy. A key role in their pathogenesis is played by the placenta, which is the source of hormones and other important regulatory molecules providing the metabolic and endocrine homeostasis of the fetal-placental unit. Since obstetric syndromes are characterized by important maternal and neonatal morbidity and mortality worldwide, numerous efforts have been made over the years to prevent and treat them. Due to their complex pathogenesis, however, the therapy is poor and not very effective. Therefore, great emphasis is currently given to the prevention of these diseases through the identification of biochemical and biophysical markers, among which placental factors play a crucial role. The increasing knowledge of the role of placental molecules can indeed lead to the development of new therapeutic and diagnostic tools.

Pregnancy-specific glycoproteins bind integrin αIIbβ3 and inhibit the platelet-fibrinogen interaction

Pregnancy-specific glycoproteins (PSGs) are immunoglobulin superfamily members encoded by multigene families in rodents and primates. In human pregnancy, PSGs are secreted by the syncytiotrophoblast, a fetal tissue, and reach a concentration of up to 400 ug/ml in the maternal bloodstream at term. Human and mouse PSGs induce release of anti-inflammatory cytokines such as IL-10 and TGFβ1 from monocytes, macrophages, and other cell types, suggesting an immunoregulatory function. RGD tri-peptide motifs in the majority of human PSGs suggest that they may function like snake venom disintegrins, which bind integrins and inhibit interactions with ligands. We noted that human PSG1 has a KGD, rather than an RGD motif. The presence of a KGD in barbourin, a platelet integrin αIIbβ3 antagonist found in snake venom, suggested that PSG1 may be a selective αIIbβ3 ligand. Here we show that human PSG1 binds αIIbβ3 and inhibits the platelet – fibrinogen interaction. Unexpectedly, however, the KGD is not critical as multiple PSG1 domains independently bind and inhibit αIIbβ3 function. Human PSG9 and mouse Psg23 are also inhibitory suggesting conservation of this function across primate and rodent PSG families. Our results suggest that in species with haemochorial placentation, in which maternal blood is in direct contact with fetal trophoblast, the high expression level of PSGs reflects a requirement to antagonise abundant (3 mg/ml) fibrinogen in the maternal circulation, which may be necessary to prevent platelet aggregation and thrombosis in the prothrombotic maternal environment of pregnancy.

Novel biomarkers for predicting intrauterine growth restriction: a systematic review and meta-analysis

BACKGROUND

Several biomarkers for predicting intrauterine growth restriction (IUGR) have been proposed in recent years. However, the predictive performance of these biomarkers has not been systematically evaluated.

OBJECTIVE

To determine the predictive accuracy of novel biomarkers for IUGR in women with singleton gestations.

SEARCH STRATEGY

Electronic databases, reference list checking and conference proceedings.

SELECTION CRITERIA

Observational studies that evaluated the accuracy of novel biomarkers proposed for predicting IUGR.

DATA COLLECTION AND ANALYSIS

Data were extracted on characteristics, quality and predictive accuracy from each study to construct 2×2 tables. Summary receiver operating characteristic curves, sensitivities, specificities and likelihood ratios (LRs) were generated.

MAIN RESULTS

A total of 53 studies, including 39,974 women and evaluating 37 novel biomarkers, fulfilled the inclusion criteria. Overall, the predictive accuracy of angiogenic factors for IUGR was minimal (median pooled positive and negative LRs of 1.7, range 1.0-19.8; and 0.8, range 0.0-1.0, respectively). Two small case-control studies reported high predictive values for placental growth factor and angiopoietin-2 only when IUGR was defined as birthweight centile with clinical or pathological evidence of fetal growth restriction. Biomarkers related to endothelial function/oxidative stress, placental protein/hormone, and others such as serum levels of vitamin D, urinary albumin:creatinine ratio, thyroid function tests and metabolomic profile had low predictive accuracy.

CONCLUSIONS

None of the novel biomarkers evaluated in this review are sufficiently accurate to recommend their use as predictors of IUGR in routine clinical practice. However, the use of biomarkers in combination with biophysical parameters and maternal characteristics could be more useful and merits further research.

Early expression of pregnancy-specific glycoprotein 22 (PSG22) by trophoblast cells modulates angiogenesis in mice

Mouse and human pregnancy-specific glycoproteins (PSG) are known to exert immunomodulatory functions during pregnancy by inducing maternal leukocytes to secrete anti-inflammatory cytokines that promote a tolerogenic decidual microenvironment. Many such anti-inflammatory mediators also function as proangiogenic factors, which, along with the reported association of murine PSG with the uterine vasculature, suggest that PSG may contribute to the vascular adaptations necessary for successful implantation and placental development. We observed that PSG22 is strongly expressed around the embryonic crypt on Gestation Day 5.5, indicating that trophoblast giant cells are the main source of PSG22 during the early stages of pregnancy. PSG22 treatment up-regulated the secretion of transforming growth factor beta 1 and vascular endothelial growth factor A (VEGFA) in murine macrophages, uterine dendritic cells, and natural killer cells. A possible role of PSGs in uteroplacental angiogenesis is further supported by the finding that incubation of endothelial cells with PSG22 resulted in the formation of tubes in the presence and absence of VEGFA. We determined that PSG22, like human PSG1 and murine PSG17 and PSG23, binds to the heparan sulfate chains in syndecans. Therefore, our findings indicate that despite the independent evolution and expansion of human and rodent PSG, members in both families have conserved functions that include their ability to induce anti-inflammatory cytokines and proangiogenic factors as well as to induce the formation of capillary structures by endothelial cells. In summary, our results indicate that PSG22, the most abundant PSG expressed during mouse early pregnancy, is likely a major contributor to the establishment of a successful pregnancy.

Screening for pre-eclampsia using serum placental growth factor and endoglin with Down's syndrome Quadruple test markers

OBJECTIVE

To estimate the pre-eclampsia screening performance of placental growth factor (PlGF) and endoglin with second-trimester Quadruple test markers used for antenatal Down's syndrome screening.

METHODS

A nested case-control study of 88 pregnant women with known early second-trimester Down's syndrome Quadruple test marker levels who subsequently developed pre-eclampsia and 275 unaffected controls. Frozen maternal serum samples were thawed and assayed for PlGF and endoglin. Monte Carlo simulation was used to estimate the pre-eclampsia screening performance of a pre-eclampsia detection algorithm using the Quadruple test markers with or without the addition of PlGF and/or endoglin.

RESULTS

Median PlGF was 33% lower (95% confidence interval 24-41%) and endoglin 31% (20-43%) higher in pre-eclampsia than in unaffected pregnancies. Adding PlGF to the Quadruple test markers increased the pre-eclampsia detection rate from 34% to 45% at a 5% false-positive rate - it increased it to 43% with endoglin and to 50% with both. The corresponding estimates for early pre-eclampsia (before 36 weeks' gestation) were a few percentage points higher (48%, 48% and 55% respectively). Including information on parity, pre-eclampsia in a previous pregnancy, family history (woman's mother) and assuming a pre-eclampsia prevalence of 2%, the detection rates for a 5% false-positive rate were 39% with the Quadruple test markers, 48% with addition of endoglin, 49% with addition of PlGF, and 54% with addition of both.

CONCLUSIONS

Adding PlGF to the Quadruple test Down's syndrome screening markers improves pre-eclampsia screening performance. There is a modest extra benefit in also adding the measurement of endoglin.

The vascular endothelial growth factor family in adverse pregnancy outcomes

BACKGROUND

Pre-eclampsia, small-for-gestational-age infants, preterm birth and recurrent miscarriage complicate a significant number of pregnancies. The vascular endothelial growth factor (VEGF) family of angiogenic growth factors is implicated in the pathophysiology of these complications. We aimed to elucidate the role of these angiogenic factors in placentation and to evaluate the predictive value of their protein concentrations and genetic variations in pregnancy complications.

METHODS

We performed a systematic search of PubMed, and retrieved original articles. The search included a combination of terms such as VEGF-A, placental growth factor (PlGF), kinase insert domain receptor, fms-like-tyrosine-kinase receptor 1, soluble fms-like-tyrosine-kinase receptor 1, pre-eclampsia, small-for-gestational-age infants, preterm birth, recurrent miscarriage, placenta, prediction and polymorphisms.

RESULTS

This review summarizes the current knowledge of the roles of the VEGF family in early placentation and of the abnormalities in maternal plasma and placental expression of angiogenic proteins in adverse pregnancy outcomes compared with normal pregnancy. PlGF and sFLT-1 in combination with other clinical and biochemical markers in late first or second trimester appear to predict early-onset pre-eclampsia with a high sensitivity and specificity. However, VEGF family proteins do not have sufficient power to accurately predict late-onset pre-eclampsia, small-for-gestational age pregnancies or preterm birth. Functional polymorphisms in these angiogenic genes are implicated in pregnancy complications, but their contribution appears to be minor.

CONCLUSIONS

Although the VEGF family has important roles in normal and complicated pregnancy, the current predictive value of the VEGF family as biomarkers appears to be limited to early-onset pre-eclampsia.

The value of early second trimester PAPP-A and ADAM12 in screening for pre-eclampsia

OBJECTIVE

To estimate the pre-eclampsia screening performance of PAPP-A (pregnancy-associated plasma protein-A) and ADAM12 (A Disintegrin And Metalloprotease 12) in the early second trimester of pregnancy.

METHODS

Stored frozen serum samples from a previously published nested case-control study comprising 77 women who developed pre-eclampsia and 224 unaffected controls were thawed and assayed for PAPP-A and ADAM12. Levels were converted into multiple of the unaffected median (MoM) values.

RESULTS

Neither PAPP-A or ADAM12 were significantly different in women who developed pre-eclamspia compared with unaffected controls (PAPP-A: 0.97 MoM [95% confidence interval 0.73 to 1.25], ADAM12: 1.01 MoM [0.91 to 1.13]).

CONCLUSION

Our results do not support the use of PAPP-A or ADAM12 in early second trimester antenatal screening for pre-eclampsia.

Discovery of the serum biomarker proteins in severe preeclampsia by proteomic analysis

Preeclapsia (PE) is a severe disorder that occurs during pregnancy, leading to maternal and fetal morbidity and mortality. PE affects about 3-8% of all pregnancies. In this study, we conducted liquid chromatography- mass spectrometry/mass spectrometry (LC-MS/MS) to analyze serum samples depleted of the six most abundant proteins from normal and PE-affected pregnancies to profile serum proteins. A total of 237 proteins were confidently identified with <1% false discovery rate from the two groups of duplicate analysis. The expression levels of those identified proteins were compared semiquantitatively by spectral counting. To further validate the candidate proteins with a quantitative mass spectrometric method, selective reaction monitoring (SRM) and enzyme linked immune assay (ELISA) of serum samples collected from pregnant women with severe PE (n = 8) or normal pregnant women (n = 5) was conducted. α2- HS-glycoprotein (AHSG), retinol binding protein 4 (RBP4) and α-1-microglobulin/bikunin (AMBP) and Insulin like growth factor binding protein, acid labile subunit (IGFBP-ALS) were confirmed to be differentially expressed in PE using SRM (P<0.05). Among these proteins, AHSG was verified by ELISA and showed a statistically significant increase in PE samples when compared to controls.

Association of pregnancy-associated plasma protein A polymorphism with preeclampsia - a pilot study

OBJECTIVES

The aim of the study was to investigate genetic and biochemical background of PAPP-A (pregnancy-associated plasma protein A) in patients with risk pregnancies.

DESIGN AND METHODS

Five PAPP-A gene polymorphisms and PAPP-A maternal serum levels were studied together in 165 women in third trimester pregnancies complicated with threatening preterm labor (n=98), preeclampsia (n=35), intrauterine growth restriction (n=34) and ICP (intrahepatic cholestasis of pregnancy) (n=15). 114 healthy pregnant women served as controls.

RESULTS

Preeclamptic patients had significantly higher frequency of TT genotype of Cys327Cys polymorphism compared to controls (p<0.01). Patients with ICP had increased serum levels of PAPP-A compared to controls and correlation analysis showed significant relationship between PAPP-A and CRP (C-reactive protein) in the patients with intrauterine growth restriction (r=0.49, p=0.007).

CONCLUSION

Our study indicates the association of TT genotype of Cys327Cys polymorphism of the PAPP-A gene with preeclampsia. However, further study with larger groups of preeclamptic patients is needed to confirm our results.

Metabolic profiling uncovers a phenotypic signature of small for gestational age in early pregnancy

Being born small for gestational age (SGA) confers increased risks of perinatal morbidity and mortality and increases the risk of cardiovascular complications and diabetes in later life. Accumulating evidence suggests that the etiology of SGA is usually associated with poor placental vascular development in early pregnancy. We examined metabolomic profiles using ultra performance liquid chromatography-mass spectrometry (UPLC-MS) in three independent studies: (a) venous cord plasma from normal and SGA babies, (b) plasma from a rat model of placental insufficiency and controls, and (c) early pregnancy peripheral plasma samples from women who subsequently delivered a SGA baby and controls. Multivariate analysis by cross-validated Partial Least Squares Discriminant Analysis (PLS-DA) of all 3 studies showed a comprehensive and similar disruption of plasma metabolism. A multivariate predictive model combining 19 metabolites produced by a Genetic Algorithm-based search program gave an Odds Ratio for developing SGA of 44, with an area under the Receiver Operator Characteristic curve of 0.9. Sphingolipids, phospholipids, carnitines, and fatty acids were among this panel of metabolites. The finding of a consistent discriminatory metabolite signature in early pregnancy plasma preceding the onset of SGA offers insight into disease pathogenesis and offers the promise of a robust presymptomatic screening test.