Second-trimester uterine artery Doppler pulsatility index and maternal serum PP13 as markers of pre-eclampsia

Predictive Capabilities of Human Leukocyte Antigen-G and Galectin-13 Levels in the Amniotic Fluid and Maternal Blood for the Pregnancy Outcome

Background and Objectives: Increasing evidence points to the significant role of the angiogenic factor levels in screening for pregnancy outcome. To examine the potential relationship between concentrations of placental protein 13 (PP13) and soluble human leukocyte antigen-G (sHLA-G) in maternal serum and amniotic fluid at 16-23 weeks of gestation and the sonographic features of pregnancy as well as pregnancy outcome. Materials and Methods: PP13 and sHLA-G in serum and amniotic fluid, fetal biometrical data, and placental volume and perfusion indices were determined in 71 euploid, singleton pregnancies. Results: The serum sHLA-G level exhibits a negative correlation with the serum PP13 level (r = -0.186, p < 0.001) and a positive correlation with the sHLA-G level in amniotic fluid (r = 0.662, p < 0.001). A significant correlation was found between serum sHLA-G level and placental volume (r = 0.142, p < 0.05) and between amniotic sHLA-G level and placental perfusion (r = -0.450, p < 0.001). A low amniotic PP13 level significantly predicted the birth weight (r = -0.102, p < 0.05), the duration of pregnancy (r = -0.155, p < 0.05), and the fetal abdominal circumference (r = -0.098, p < 0.05). Conclusions: PP13 assayed in amniotic fluid might be a potential marker of fetal growth, and sHLA-G can be an adjunct modality reflecting placental sonographic parameters.

Predictive Performance of Placental Protein 13 for Screening Preeclampsia in the First Trimester: A Systematic Review and Meta-Analysis

Preeclampsia is a pregnancy-specific syndrome that affects maternal and neonatal mortality. Several serum biomarkers can be used to predict preeclampsia. Among these proteins, placental protein 13 (PP13) has received progressively more interest in recent studies. The decrease in PP13 expression is one of the earliest signs for the development of preeclampsia and has shown its predictive performance for preeclampsia. In this meta-analysis, we collected 17 observational studies with 40,474 pregnant women. The overall sensitivity of PP13 to predict preeclampsia was 0.62 [95% confidence interval (CI) = 0.49–0.74], the specificity was 0.84 (95%CI = 0.81–0.86), and the diagnostic odds ratio was nine (95%CI = 5–15). The area under the curve for summary receiver operating characteristic was 0.84. We then chose the early-onset preeclampsia as a subgroup. The sensitivity of early-onset subgroup was 0.63 (95%CI = 0.58–0.76), the specificity was 0.85 (95%CI = 0.82–0.88), and the diagnostic odds ratio was 10 (95%CI = 6–18). The findings of our meta-analysis indicate that PP13 may be an effective serum biomarker for the predictive screening of preeclampsia. Nonetheless, large prospective cohort studies and randomized controlled trials are expected to uncover its application in clinical practice. The heterogeneity of the original trials may limit the clinical application of PP13.

Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=188948 The meta-analysis was registered in PROSPERO (CRD42020188948).

Galectin 13 (PP13) Facilitates Remodeling and Structural Stabilization of Maternal Vessels during Pregnancy

Galectins regulate cell growth, proliferation, differentiation, apoptosis, signal transduction, mRNA splicing, and interactions with the extracellular matrix. Here we focus on the galectins in the reproductive system, particularly on a group of six galectins that first appears in anthropoid primates in conjunction with the evolution of highly invasive placentation and long gestation. Of these six, placental protein 13 (PP13, galectin 13) interacts with glycoproteins and glycolipids to enable successful pregnancy. PP13 is related to the development of a major obstetric syndrome, preeclampsia, a life-threatening complication of pregnancy which affects ten million pregnant women globally. Preeclampsia is characterized by hypertension, proteinuria, and organ failure, and is often accompanied by fetal loss and major newborn disabilities. PP13 facilitates the expansion of uterine arteries and veins during pregnancy in an endothelial cell-dependent manner, via the eNOS and prostaglandin signaling pathways. PP13 acts through its carbohydrate recognition domain that binds to sugar residues of extracellular and connective tissue molecules, thus inducing structural stabilization of vessel expansion. Further, decidual PP13 aggregates may serve as a decoy that induces white blood cell apoptosis, contributing to the mother's immune tolerance to pregnancy. Lower first trimester PP13 level is one of the biomarkers to predict the subsequent risk to develop preeclampsia, while its molecular mutations/polymorphisms that are associated with reduced PP13 expression are accompanied by higher rates of preeclampsia We propose a targeted PP13 replenishing therapy to fight preeclampsia in carriers of these mutations.

Pregnancy Galectinology: Insights Into a Complex Network of Glycan Binding Proteins

Galectins are a phylogenetically conserved family of soluble β-galactoside binding proteins, consisting of 15 different types, each with a specific function. Galectins contribute to placentation by regulating trophoblast development, migration, and invasion during early pregnancy. In addition, galectins are critical players regulating maternal immune tolerance to the embedded embryo. Recently, the role of galectins in angiogenesis during decidualization and in placenta formation has gained attention. Altered expression of galectins is associated with abnormal pregnancies and infertility. This review focuses on the role of galectins in pregnancy-associated processes and discusses the relevance of galectin-glycan interactions as potential therapeutic targets in pregnancy disorders.

Circulating Heme Oxygenase-1: Not a Predictor of Preeclampsia but Highly Expressed in Pregnant Women Who Subsequently Develop Severe Preeclampsia

Preeclampsia is the major cause of maternal and fetal deaths worldwide. Circulating biomarker concentrations to predict preeclampsia must be determined. Therefore, the objective was to evaluate heme oxygenase-1 (HO-1) concentration in both plasma and urine samples from pregnant women before the development of preeclampsia and to identify a potential biomarker for preeclampsia development. We performed a case-control study nested in a prospective study cohort at University Hospital of the Ribeirao Preto Medical School, University of São Paulo (HCFMRP-USP), Ribeirao Preto, Brazil. Of 1400 pregnant women evaluated at 20–25 weeks of gestation, 460 delivered in hospitals outside our institution. Of 940 pregnant women who completed the protocol, 30 developed preeclampsia (cases, 14 cases of severe preeclampsia and 16 cases of mild preeclampsia). Healthy pregnant women (controls, n = 90) were randomly selected from the remaining 910 participants. HO-1 concentration was evaluated in plasma/urine samples by using a commercial enzyme-linked immunosorbent assay kit. We found similar HO-1 levels in the plasma and urine for case and control groups. In the subgrouped preeclampsia, lower plasma HO-1 levels were found in mild compared with severe preeclampsia. We conclude that plasma HO-1 levels were not altered at 20–25 weeks of gestation before the manifestation of preeclampsia symptoms. Pregnant women who subsequently develop severe preeclampsia show higher expression of HO-1. This may be indicative of important underlying pathophysiologic mechanisms that differentiate between mild and severe preeclampsia and may possibly be related to a higher prooxidative status even before the development of clinical symptoms.

Placental protein 13: An important biological protein in preeclampsia

Placental protein 13 (PP13), a glycan binding protein predominantly expressed in syncytiotrophoblast, dimeric in nature, lacks N-terminal signal peptide, bypasses the endoplasmic reticulum, and secretes into maternal circulation as exosomes or microvesicles. PP13 has jelly roll fold conformation with conserved carbohydrate recognition domain which specifically binds to β-galactosides of the glycan receptors during placentation. PP13 binds to glycosylated receptors on human erythrocytes and brings about hemagglutination by the property of lectin activity; other functions are immunoregulation and vasodilation during placentation and vascularization. The gene LGALS13 located on 19q13.2 comprising four exons expresses a 32-kDa protein with 139 amino acid residues, PP13. Impaired expression due to mutation in the gene leads to a nonfunctional truncated PP13. The low serum levels predict high risk for the onset of preeclampsia or obstetric complications. Hence, PP13 turned to be an early marker for risk assessment of preeclampsia. The recombinant PP13 and monoclonal antibodies availability help for replenishing PP13 in conditions with low serum levels and for detection and prevention of preeclampsia, respectively.

Early second trimester maternal serum markers in the prediction of gestational diabetes mellitus

AIMS/INTRODUCTION

To determine whether maternal serum markers in the early second trimester are useful for prediction of gestational diabetes mellitus (GDM).

MATERIALS AND METHODS

A total of 876 singleton pregnancies were recruited in the present study. Blood samples were collected during 16-20 gestational weeks. GDM women were diagnosed by an oral glucose tolerance test during 24-28 gestational weeks. A total of 56 women with GDM and 73 healthy pregnant women were selected. Maternal serum concentrations of placental protein 13 (PP13), pentraxin 3 (PTX3), soluble fms-like tyrosine kinase-1 (sFlt-1), myostatin and follistatin (FST) were detected at 16-20 weeks' gestation. All of these markers concentrations were expressed as multiples of the medians. The Mann-Whitney U-test was used for comparison of the multiples of the medians of different concentrations of these five serum markers between the GDM group and the control group. Receiver operating characteristic curve analysis was applied to assess the sensitivity and specificity of significant serum markers from a Mann-Whitney U-test comparison.

RESULTS

Compared with healthy pregnancies, the serum levels of PP13, PTX3, sFlt-1, myostatin and FST in the early second trimester were significantly increased in patients who had developed GDM late. In screening for GDM by PP13, PTX3, sFlt-1, myostatin and FST, the detection rates were 92.3, 94.9, 94.9, 92.5 and 92.3%, respectively at 80% specificity. PTX3 and sFlt-1 were the most sensitive markers.

CONCLUSIONS

Maternal serum markers including PP13, PTX3, sFlt-1, myostatin and FST increase in the early second trimester of women with GDM. These five markers, especially PTX3 and sFlt-1, could have the value of prediction for those patients who would develop GDM in the late second trimester.

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.

Galectin-13, a different prototype galectin, does not bind β-galacto-sides and forms dimers via intermolecular disulfide bridges between Cys-136 and Cys-138

During pregnancy, placental protein-13 (galectin-13) is highly expressed in the placenta and fetal tissue, and less so in maternal serum that is related to pre-eclampsia. To understand galectin-13 function at the molecular level, we solved its crystal structure and discovered that its dimer is stabilized by two disulfide bridges between Cys136 and Cys138 and six hydrogen bonds involving Val135, Val137, and Gln139. Native PAGE and gel filtration demonstrate that this is not a crystallization artifact because dimers also form in solution. Our biochemical studies indicate that galectin-13 ligand binding specificity is different from that of other galectins in that it does not bind β-galactosides. This is partly explained by the presence of Arg53 rather than His53 at the bottom of the carbohydrate binding site in a position that is crucial for interactions with β-galactosides. Mutating Arg53 to histidine does not re-establish normal β-galactoside binding, but rather traps cryoprotectant glycerol molecules within the ligand binding site in crystals of the R53H mutant. Moreover, unlike most other galectins, we also found that GFP-tagged galectin-13 is localized within the nucleus of HeLa and 293 T cells. Overall, galectin-13 appears to be a new type of prototype galectin with distinct properties.

Galectins: Double-edged Swords in the Cross-roads of Pregnancy Complications and Female Reproductive Tract Inflammation and Neoplasia

Galectins are an evolutionarily ancient and widely expressed family of lectins that have unique glycan-binding characteristics. They are pleiotropic regulators of key biological processes, such as cell growth, proliferation, differentiation, apoptosis, signal transduction, and pre-mRNA splicing, as well as homo- and heterotypic cell-cell and cell-extracellular matrix interactions. Galectins are also pivotal in immune responses since they regulate host-pathogen interactions, innate and adaptive immune responses, acute and chronic inflammation, and immune tolerance. Some galectins are also central to the regulation of angiogenesis, cell migration and invasion. Expression and functional data provide convincing evidence that, due to these functions, galectins play key roles in shared and unique pathways of normal embryonic and placental development as well as oncodevelopmental processes in tumorigenesis. Therefore, galectins may sometimes act as double-edged swords since they have beneficial but also harmful effects for the organism. Recent advances facilitate the use of galectins as biomarkers in obstetrical syndromes and in various malignancies, and their therapeutic applications are also under investigation. This review provides a general overview of galectins and a focused review of this lectin subfamily in the context of inflammation, infection and tumors of the female reproductive tract as well as in normal pregnancies and those complicated by the great obstetrical syndromes.

Pulsatility index in combination with biomarkers or mean arterial pressure for the prediction of pre-eclampsia: Systematic literature review and meta-analysis

INTRODUCTION

Our objective was to perform a meta-analysis examining the sensitivity of pulsatility index (PI) and various biomarkers and PI and mean arterial pressure (MAP) for the prediction of pre-eclampsia.

MATERIAL AND METHODS

PubMed, CENTRAL, and Embase databases were searched from inception until 8 May 2014 using combinations of the search terms: pre-eclampsia, ultrasonography, pregnancy, biomarker, mean arterial pressure, placental protein 13, pregnancy-associated plasma protein-A, placental growth factor, activin A, inhibin A, pulsatility index. The pooled sensitivity of PI + biomarkers and PI + MAP were calculated, and reported with corresponding 95% confidence intervals (CIs).

RESULTS

Fifteen studies were included in the meta-analysis. The pooled sensitivity of all biomarkers for the prediction of pre-eclampsia was 0.669 (95% CI 0.610-0.723), for the prediction of early-onset pre-eclampsia was 0.830 (95% CI 0.794-0.861), and for the prediction of late-onset pre-eclampsia was 0.564 (95% CI 0.499-0.627). Similarly, the predictive ability of PI + MAP for early-onset pre-eclampsia was good (sensitivity 0.894), while that for late-onset was poor (sensitivity 0.570).

CONCLUSION

The combination of PI and different biomarkers or MAP exhibits a good predictive ability for early-onset pre-eclampsia, and poor predictive ability for late-onset pre-eclampsia.

Galectin-13/PP-13 expression in term placentas of gestational diabetes mellitus pregnancies

INTRODUCTION

Gestational diabetes mellitus (GDM) is an increasing harm in pregnancy. Inflammatory processes in the placenta seem to have an influence on pathogenesis besides known factors like maternal BMI. Galectin-13 (gal-13) is an immunoregulatory protein, which is suspected to play a role in development of GDM in the placenta.

METHODS

A total of 40 placentas were obtained from women treated for gestational diabetes mellitus. Placental tissue for control group was obtained from 40 women with normal pregnancy. We investigated the protein expression of gal-13 in term placentas with immunohistochemistry and immunofluorescence. Immunohistochemical staining was analyzed with the semi-quantified IRS score. Gal-13 serum levels were performed with ELISA on a total of 20 probes from women with GDM and healthy control pregnancies in the third trimester.

RESULTS

Gal-13 was found in syncytiotrophoblast, in nuclei of syncytiotrophoblast and trophoblast cells as well in extravillous trophoblast cells of normal placentas. In GDM placentas, gal-13 expression was significantly decreased in all of these examined cell types (syncytiotrophoblast p = 0.003, nuclei of syncytiotrophoblast p = 0.007; extravillous trophoblast cells p = 0.001). The ELISA showed a significant lower gal-13 serum level in blood from pregnant women with GDM in comparison to healthy controls.

DISCUSSION

As gal-13 with its anti-inflammatory functions plays a role in regulation of maternal immune system, a lack of gal-13 may contribute to an imbalance in inflammation processes in the placenta during pregnancy and therefore influences development of GDM.

Placental Protein 13 (PP13) - A Placental Immunoregulatory Galectin Protecting Pregnancy

Galectins are glycan-binding proteins that regulate innate and adaptive immune responses, and some confer maternal-fetal immune tolerance in eutherian mammals. A chromosome 19 cluster of galectins has emerged in anthropoid primates, species with deep placentation and long gestation. Three of the five human cluster galectins are solely expressed in the placenta, where they may confer additional immunoregulatory functions to enable deep placentation. One of these is galectin-13, also known as Placental Protein 13 (PP13). It has a "jelly-roll" fold, carbohydrate-recognition domain and sugar-binding preference resembling other mammalian galectins. PP13 is predominantly expressed by the syncytiotrophoblast and released from the placenta into the maternal circulation. Its ability to induce apoptosis of activated T cells in vitro, and to divert and kill T cells as well as macrophages in the maternal decidua in situ, suggests important immune functions. Indeed, mutations in the promoter and an exon of LGALS13 presumably leading to altered or non-functional protein expression are associated with a higher frequency of preeclampsia and other obstetrical syndromes, which involve immune dysregulation. Moreover, decreased placental expression of PP13 and its low concentrations in first trimester maternal sera are associated with elevated risk of preeclampsia. Indeed, PP13 turned to be a good early biomarker to assess maternal risk for the subsequent development of pregnancy complications caused by impaired placentation. Due to the ischemic placental stress in preterm preeclampsia, there is increased trophoblastic shedding of PP13 immunopositive microvesicles starting in the second trimester, which leads to high maternal blood PP13 concentrations. Our meta-analysis suggests that this phenomenon may enable the potential use of PP13 in directing patient management near to or at the time of delivery. Recent findings on the beneficial effects of PP13 on decreasing blood pressure due to vasodilatation in pregnant animals suggest its therapeutic potential in preeclampsia.

ADAM12s and PP13 as first trimester screening markers for adverse pregnancy outcome

BACKGROUND

The aim of the study was to assess the screening performance of first trimester maternal serum measurements of A-disintegrin-and-metalloprotease 12-s (ADAM12s) and placental protein 13 (PP13) for preeclampsia (PE), gestational hypertension (GH) and small-for-gestational-age (SGA) fetuses.

METHODS

In this retrospective case-control study 220 pregnant women were matched for gestational and maternal age at sampling. Results were expressed as multiples of the median (MoM) and compared using Kruskal-Wallis and Mann-Whitney U-test. Screening performance was assessed by receiver operator characteristics (ROC) curves and area under the curve (AUC).

RESULTS

Seventeen cases of PE, 30 cases of GH and eight cases of SGA fetuses were matched with 165 controls. ROC-analysis yielded AUCs for ADAM12s and PP13 of 0.63 and 0.59 for PE, 0.68 and 0.57 for GH and 0.59 and 0.62 for SGA, respectively. Combined ADAM12 and PP13 did not improve the AUC value. When the specificity was set at 80%, corresponding detection rate of ADAM12s was 52% for GH.

CONCLUSIONS

Combined ADAM12s and PP13 measurements do not predict adverse pregnancy outcome, but decreased first trimester ADAM12s levels are associated with GH.

Expression and function of galectins in the endometrium and at the human feto-maternal interface

Galectins are classified as lectins that share structural similarities and bind β-galactosides via a conserved carbohydrate recognition domain. So far 16 out of 19 identified galectins were shown to be present in humans and numerous studies revealed galectins as pivotal modulators of cell death, differentiation and growth. Galectins were highlighted to interact with both the adaptive and innate immune response. In the field of reproductive medicine and placenta research different roles for galectins have been proposed. Several galectins, being abundantly present at the human feto-maternal interphase and endometrium, were hypothesized to significantly contribute to endometrial receptivity and pregnancy physiology. Hence, this review outlines selected aspects of galectin action within endometrial function and at the feto-maternal interphase. Further current knowledge on galectins in reproductive and pregnancy disorders like endometriosis, abortion or preeclampsia is summarized.

Placental protein 13 (PP13): a new biological target shifting individualized risk assessment to personalized drug design combating pre-eclampsia

BACKGROUND

Pre-eclampsia affects 2-7% of all pregnant women and is a major cause of maternal and fetal morbidity and mortality. The etiology of pre-eclampsia is still unknown but it is well documented that impaired placentation is a major contributor to its development. One of the placenta-specific proteins is placental protein 13 (PP13). Lower first trimester levels of maternal serum PP13 and its encoding placental mRNA are associated with the development of both early and late-onset severe pre-eclampsia. In cases where this protein is mutated, the frequency of pre-eclampsia is higher.

METHODS

19 out of 68 studies on PP13, published between January 2006 and September 2012, were used to evaluate the value of maternal blood PP13 as a marker of pre-eclampsia.

RESULTS

A meta-analysis presented in this review shows that low serum levels of PP13 in the first trimester of pregnancy can predict the development of pre-eclampsia later in pregnancy. Although some functions of this protein have been assessed in in vitro experiments, the in vivo functions of PP13 are still unknown, especially when circulating in the maternal bloodstream. A recent pilot study has shown that in gravid rats PP13 causes significant vasodilatation, reduced blood pressure and increased maternal uterine artery remodeling.

CONCLUSION

Reviewing these effects of PP13, the authors propose the use of PP13 as a new drug candidate. Replenishing PP13 in those women with low serum levels early in pregnancy may help prepare their vasculature for pregnancy. This novel pharmacological approach to combat pre-eclampsia is presented as a new direction to transfer from individualized risk to personalized prevention.

Biomarkers in pre-eclampsia: a novel approach to early detection of the disease

Pre-eclampsia is a unique disorder of human pregnancy with a great impact on maternal and perinatal morbidity and mortality worldwide and especially in developing countries. The aetiology is still unknown and the pathophysiology of the disease is the subject of extensive investigation. Recently, much of the interest of the investigators for the prediction of pre-eclampsia has been aimed at measurable manifestations of abnormal placentation, endothelial dysfunction and feto-maternal unit perfusion. Biomarkers constitute a novel approach to an early detection of the disease. Low maternal serum levels of PAPP-A and PP13 early in pregnancy are predictive for emerging pre-eclampsia. On the other hand, increased levels of homocysteine, ADMA, sEng, leptin and sFlt-1 in the 1st trimester, signal the onset of the disease later in pregnancy. After the onset of pre-eclampsia, increased serum levels of PAPP-A, ADMA, homocysteine and sFlt-1 are associated with the severity of the disease. The identification of biomarkers which can contribute to the early detection of pre-eclampsia is essential. It could then be possible to apply better surveillance and treatment protocols in such patients.

First trimester serum analytes, maternal characteristics and ultrasound markers to predict pregnancies at risk for preterm birth

INTRODUCTION

Markers of placental dysfunction are used for risk prediction of adverse obstetric outcomes including preeclampsia and growth restriction. Although medically indicated preterm birth is often distinguished from spontaneous preterm birth, we hypothesize that similar placental dysfunction may underlay all preterm birth. We aimed to investigate whether first trimester placental protein 13 (PP-13), pregnancy associated plasma protein A (PAPP-A) and uterine artery pulsatility index, with maternal characteristics could be used to predict all preterm birth.

METHODS

Prospective cohort study of singleton gestations between 11 and 14 weeks who underwent serum measurement of PP-13, PAPP-A, and measurement of uterine artery Doppler pulsatility index. Primary outcomes were preterm birth (PTB) at less than 37 and 33 weeks. Analysis performed both including and excluding preeclampsia to assess the utility of the predictors for all types of preterm birth. Predictive models assembled using logistic regression with each predictor alone and in combination, along with maternal characteristics. Predictive utility of models was assessed using receiver operating curve (ROC) analysis and sensitivities for fixed false positive values.

RESULTS

Of 471 women, PTB occurred in 12.5% and early PTB (<33 weeks) occurred in 4.7%. PP-13 was decreased in PTB <37 weeks. PAPP-A was decreased in a dose-response pattern for PTB at <37 weeks and <33 weeks. Uterine artery pulsatility index was increased in early PTB. All patterns of predictors remained the same whether patients with preeclampsia were excluded or included suggesting predictive utility for all causes of PTB. Predictive models all demonstrated good predictive ability with ROC ≥ 0.90.

CONCLUSIONS

PP-13, PAPP-A, and uterine artery Doppler pulsatility index obtained in the first trimester are good predictors of all types of preterm birth, both indicated and spontaneous. Models including first trimester markers combined with maternal characteristics demonstrated good predictive ability and could be investigated for application of targeted prophylactic strategies.

Cell free expression of hif1α and p21 in maternal peripheral blood as a marker for preeclampsia and fetal growth restriction

Preeclampsia, a severe unpredictable complication of pregnancy, occurs in 6% of pregnancies, usually in the second or third trimester. The specific etiology of preeclampsia remains unclear, although the pathophysiological hallmark of this condition appears to be an inadequate blood supply to the placenta. As a result of the impaired placental blood flow, intrauterine growth restriction (IUGR) and consequential fetal oxidative stress may occur. Consistent with this view, pregnancies complicated by preeclampsia and IUGR are characterized by up-regulation of key transcriptional regulators of the hypoxic response including, hif1α and as well as p53 and its target genes. Recently, the presence of circulating cell-free fetal RNA has been documented in maternal plasma. We speculated that pregnancies complicated by preeclampsia and IUGR, will be associated with an abnormal expression of p53 and/or hif1α related genes in the maternal plasma. Maternal plasma from 113 singleton pregnancies (72 normal and 41 complicated pregnancies) and 19 twins (9 normal and 10 complicated pregnancies) were collected and cell free RNA was extracted. The expression of 18 genes was measured by one step real-time RT-PCR and was analyzed for prevalence of positive/negative expression levels. Results indicate that, among the genes examined, cell free plasma expressions of p21 and hif1α were more prevalent in pregnancies complicated by hypoxia and/or IUGR (p<0.001). To conclude, we present in this manuscript data to support the association between two possible surrogate markers of hypoxia and common complications of pregnancy. More work is needed in order to implement these findings in clinical practice.

Screening for pre-eclampsia: a systematic review of tests combining uterine artery Doppler with other markers

AIMS

To perform a systematic review of screening for pre-eclampsia (PE) with the combination of uterine artery Doppler (UAD), maternal history, mean arterial pressure and/or maternal serum markers.

METHODS

We identified eligible studies through a search of Medline, and, for each included study, we assessed the risk of bias and extracted relevant data. We reported the performance of screening tests according to the target population (low- or high-risk), the trimester of screening (first and/or second) and the subset of PE screened for (early and late).

RESULTS

Several tests provided moderate or convincing prediction of early PE, but screening for late PE was poor. Although UAD is more accurate in the second trimester, we found encouraging results for first-trimester screening when it was combined with other markers. Performance of screening was consistently lower in populations with risk factors for PE in the maternal history.

CONCLUSIONS

We present encouraging results for the prediction of early PE, even in the first trimester of pregnancy. The different performance of tests in screening for early vs. late PE, and of low- vs. high-risk populations, supports the concept that PE is a heterogeneous disease.

Placenta-bound and body fluid PP13 and its mRNA in normal pregnancy compared to preeclampsia, HELLP and preterm delivery

OBJECTIVES

To compare the distribution of placental protein 13 (PP13) in fetal and maternal blood and amnionic fluid and to correlate it with PP13 protein and mRNA in the placenta.

METHODS

Umbilical arterial serum, amnionic fluid, maternal venous serum and placental tissues were collected from normal outcome pregnancies (N = 63) (GA>37), early onset preeclampsia (PE) (N = 12, GA: 26-33), and HELLP syndrome (N = 5, GA: 27-29). Because PE and HELLP cases delivered preterm, cases of preterm delivery (PTD) (N = 6, GA: 31-36) served as additional control. PP13 was determined by ELISA, Western blot, and immunohistochemistry. PP13 mRNA was measured by PCR (RT-PCR). Continuous parameters were compared by t-test, P < 0.05 was considered significant.

RESULTS

In women with normal pregnancy outcome significantly higher PP13 levels were found in maternal serum compared to amnionic fluid and negligible amount was found in fetal serum. A similar pattern was identified in cases of PTD with concentrations similar to term control. In PE and HELLP cases PP13 levels in amnionic fluid level were more than twice compared to maternal serum (P < 0.001). Umbilical cord level was negligible in PE but high in HELLP corresponding to the much higher level of PP13 in this patient group compared to all others. In the placenta PP13 level in term controls was higher compared to PTD. In PE and HELLP (similar early delivery time as PTD) the level was significantly higher (P < 0.01) compared to PTD or term controls. PP13 mRNA levels in term control and PTD were similar while PP13 mRNA levels in PE and HELLP placentas were significantly lower compared to term controls or PTD or the two combined. Syncytiotrophoblast labeling appeared stronger in PE and HELLP compared to term controls and PTD.

CONCLUSIONS

In all cases but HELLP, PP13 in fetal blood is very low indicating that routing of PP13 to fetal blood is limited and that the fetus is unlikely to generate PP13. PP13 mRNA is lower in the third trimester at the time of disease while protein level accumulates and become higher creating an unparallel change in the level of the mRNA and the corresponding protein.

The role of serum markers and uterine artery Doppler in identifying at-risk pregnancies

Measures of placental dysfunction, including maternal serum analytes and Doppler studies, have been linked to adverse pregnancy outcomes, although the predictive ability of any single one is poor. Improved knowledge of the multifactorial nature of many of the adverse outcomes of pregnancy has sparked interest in the use of multi-parameter models that combine maternal serum analytes with measures of placental structure and blood flow. The combination of various first-trimester and second-trimester analytes and uterine artery Doppler screening show promise as potential screening tools, but large prospective studies are needed to further define their role in clinical practice.

Effects of calcium, magnesium, low-dose aspirin and low-molecular-weight heparin on the release of PP13 from placental explants

BACKGROUND

Preeclampsia is one of the leading causes for maternal and fetal morbidity. Attempts to prevent preeclampsia have already been made using low-dose aspirin, low-molecular-weight heparin (LMWH), and calcium supplementation. Magnesium sulphate is used at the time of disease to prevent eclampsia. Here we investigated the effect of these agents on PP13 release from placental explants.

METHODS

Placentas harvested after C-section of term or preterm control and preeclampsia cases or first trimester terminations were used to obtain explants. Explants were incubated for 24h with/without respective agents, harvested, weighed and subjected to PP13 determination in the culture medium and the explant. LDH was used to determine viability. Dose response curves were obtained for each drug. P < 0.05 was considered significant.

RESULTS

Exposure to magnesium (0.7-7g/day) slightly decreased PP13 release from controls, and slightly increased it in preeclampsia and first trimester termination. Calcium (0. 3-6g/day) showed a tendency to decrease the release in control and preeclampsia, whereas in first trimester release was increased in a bell-shaped manner. Aspirin (0-250 mg/day) tended to decrease the release in controls but increased it in a bell-shaped manner in first trimester and preeclampsia. LMWH showed no effect from 0 to 80 mg/day in controls but tended to decrease PP13 release in preeclampsia and first trimester.

CONCLUSION

This data might point to a beneficial effect of aspirin and calcium supplementation in the first trimester of pregnancy and aspirin at the time of disease, although the interaction with the maternal system still needs to be elucidated.

Circulating predictive biomarkers in preeclampsia

The aim of the paper was to review promising prediction biomarkers for preeclampsia. The methods included review of abstracts on PubMed, using "preeclampsia", "biomarker", "prediction" as key words, followed by review of primary papers investigating blood based biomarkers. Angiogenic factors, such as PlGf and sFlt1, and PP13 seem presently to have the best predictive test values for preeclampsia, but sensitivity and specificity is still too low to prove useful in a population screening setting. Biomarker testing should still be part of research protocols. Biomarkers could provide useful in selecting high-risk women for prophylactic trials as well as identifying pregnancies that could profit from closer follow-up.

Pre-eclampsia: fitting together the placental, immune and cardiovascular pieces

The success of pregnancy is a result of countless ongoing interactions between the placenta and the maternal immune and cardiovascular systems. Pre-eclampsia is a serious pregnancy complication that arises from multiple potential aberrations in these systems. The pathophysiology of pre-eclampsia is established in the first trimester of pregnancy, when a range of deficiencies in placentation affect the key process of spiral artery remodelling. As pregnancy progresses to the third trimester, inadequate spiral artery remodelling along with multiple haemodynamic, placental and maternal factors converge to activate the maternal immune and cardiovascular systems, events which may in part result from increased shedding of placental debris. As we understand more about the pathophysiology of pre-eclampsia, it is becoming clear that the development of early- and late-onset pre-eclampsia, as well as intrauterine growth restriction (IUGR), does not necessarily arise from the same underlying pathology.

Options and decision-making: hypertensive disorders of pregnancy

Hypertension remains the most commonly encountered medical condition in pregnant women, complicating up to 15% of all pregnancies. It results in frequent hospital admissions, maternal morbidity and mortality and iatrogenic preterm birth with concomitant neonatal morbidity and mortality. Hypertensive disorders of pregnancy comprise a spectrum of severity ranging from a mild elevation of blood pressure to severe pre-eclampsia and hemolysis, elevated liver enzymes and low platelet syndrome that may result in transient or chronic multiorgan failure. As regular antenatal surveillance is the only manner by which to accurately identify those who are at risk, antenatal care schedules have been designed to detect hypertension and proteinuria. Early referral for specialist care for those who are at risk and those who develop hypertension is encouraged in the hope that this will translate into improved management of women with prophylactic, antihypertensive and anticonvulsant therapy. Advances in the understanding of the pathophysiology of the hypertensive disorders of pregnancy are likely to influence future research into both identifying those who are at risk and the role of interventions, and so lead to improved maternal and neonatal outcomes. This article highlights the pathophysiology of these conditions, the classification and identification of high-risk women, clinical manifestations and options for management.

Placental protein 13 as a first trimester screening marker for aneuploidy

OBJECTIVE

To determine whether Placental Protein 13 (PP13) could be an additional marker in first trimester screening for aneuploidies.

METHODS

To evaluate differences in multiples of the gestation-specific normal median (MoMs), PP13 concentrations were measured in serum samples from Down syndrome, trisomy 18 and 13 affected pregnancies and euploid singleton pregnancies (four for each case matched for duration of storage, maternal weight and age).

RESULTS

The PP13 MoM in Down syndrome cases (n = 153) was 0.91 [not statistically significant from controls (n = 853); P = 0.06; Wilcoxon rank sum test, two-tail]. PP13 MoMs were decreased in trisomy 18 (n = 38-median MoM 0.64; P < 0.0001) and trisomy 13 cases (n = 23-median MoM 0.46; P < 0.0001). There was a slight upward trend in MoM values of the Down syndrome cases with gestational weeks. The PP13 MoM was significantly correlated with the pregnancy associated plasma protein-A MoM and the free beta-subunit of human chorion gonadotrophin (fbeta-hCG) MoM.

CONCLUSION

PP13 does not seem to be a good marker for Down syndrome. PP13 MoMs are, however, significantly lower in trisomy 18 and 13 pregnancies. The addition of PP13 to the current screening test could be valuable for improving the discrimination of aneuploid from euploid pregnancies.

Risk factors and prediction of preeclampsia

Inadequate trophoblast invasion of the spiral arteries in early pregnancy, an increased inflammatory response and changes in the immune answer to paternal antigens are considered aetiological factors in preeclampsia. Searching for factors related to these angiogenic, anti-angiogenic, immunologic and inflammatory mechanisms may provide methods to determine which patient will develop preeclampsia predating the onset of the clinical manifestations of the disease. Screening for preeclampsia in the first trimester has had Limited success. Currently, maternal characteristics, clinical history, maternal serum biochemistry and uterine artery Doppler sonography before 14 weeks are being investigated. Preeclampsia in a previous pregnancy is still the strongest predictor. In the second trimester, uterine artery Doppler has a detection rate around 60% but also a high false positive rate of 25%. First trimester uterine artery Doppler studies have high sensitivity but poor specificity with a high false positive rate. Combination of first trimester uterine artery Doppler with patient characteristics and maternal serum biochemistry, specifically placental protein 13 holds promise but further evaluation is needed. Maternal serum markers including inhibin A, activin A, soluble FMS-Like tyrosine kinase 1, endoglin, pregnancy associated plasma protein A and others, when used alone have proved poor predictors of preeclampsia. Most studies have been performed by a limited group of researchers in a population with a high risk and no validation studies of any method in other populations are available. Results are difficult to compare due to differences in methodology, and differences in the end point studied.There are still no good methods of preventing preeclampsia once a high risk has been determined.

Combining biochemical and ultrasonographic markers in predicting preeclampsia: a systematic review

BACKGROUND

Early identification of pregnant women at risk for preeclampsia is a priority to implement preventive measures. Some biochemical and ultrasonographic parameters have shown promising predictive performance, but so far there is no clinically validated screening procedure.

CONTENT

Using a series of keywords, we reviewed electronic databases (Medline, Embase, all records to May 2009) reporting the performance of biological and ultrasonographic markers to predict preeclampsia, both single markers and combinations of markers. We analyzed the data according to gestational age and risk levels of the studied populations. We evaluated the methodological quality of included publications using QUADAS (quality assessment of diagnostic accuracy studies). We identified 37 relevant studies that assessed 71 different combinations of biochemical and ultrasonographic markers. Most studies were performed during the second trimester on small-scale high-risk populations with few cases of preeclampsia. Combinations of markers generally led to an increase in sensitivity and/or specificity compared with single markers. In low-risk populations, combinations including placental protein 13 (PP13), pregnancy-associated plasma protein A (PAPP-A), a disintegrin and metalloprotease-12 (ADAM12), activin A, or inhibin A measured in first or early second trimester and uterine artery Doppler in second trimester appear promising (sensitivity 60%-80%, specificity >80%). In high-risk populations, the combination of PP13 and pulsatility index in first trimester showed 90% sensitivity and 90% specificity in a single study limited to severe preeclampsia.

SUMMARY

Combinations of biochemical and ultrasonographic markers improved the performance of early prediction of preeclampsia. From a perspective of integrative medicine, large population-based studies evaluating algorithms combining multiple markers are needed, if screening approaches are to be eventually implemented.

Longitudinal Doppler measurements of spiral artery blood flow in relation to uterine artery blood flow

OBJECTIVE

The purpose of this study was to examine the longitudinal relationship between Doppler flow velocity waveforms of the spiral artery (SA) and uterine artery (UA) in pregnant women.

METHODS

Ninety-seven primigravidas with uncomplicated singleton pregnancies were analyzed. Spiral artery and combined UA velocity waveforms were assessed by transabdominal color Doppler sonography at gestational ages of 11 through 13, 14 through 17, and 18 through 24 weeks; each measurement was performed twice. The pulsatility index (PI) was calculated for the left and right UA, and the results were averaged as a combined UA. In addition, the presence of UA bilateral notching was reported. Bland-Altman plots and generalized estimating equations were used to assess intraobserver variability and the longitudinal relationship between SA and UA blood velocities.

RESULTS

A total of 284 UA and 263 SA Doppler flow measurements were analyzed. Intraobserver variability rates for the SA and UA were 0.54 and 0.90, respectively. Results showed a continuous decrease of the mean PI in the SA and UA with increasing gestational age. Uterine artery bilateral notching was reported in 35%, 9%, and 3% of the cases at gestational ages of 11 through 13, 14 through 17, and 18 through 24 weeks. Generalized estimating equation analysis showed a significant correlation (r = 0.41) between the SA and UA (P < .0001).

CONCLUSIONS

Uterine artery Doppler measurements in early pregnancy seem to accurately reflect peripheral resistance of SAs. Furthermore, trophoblastic invasion seems a continuous process in the first half of pregnancy, in which early UA bilateral notching is a physiologic event.

First trimester maternal serum placental protein 13 for the prediction of pre-eclampsia in women with a priori high risk

OBJECTIVE

To evaluate whether first trimester maternal serum PP13 can predict pre-eclampsia among women with a priori high risk.

METHOD

This was a nested case-control study. Women less than 14 weeks' gestation at increased risk of developing pre-eclampsia were recruited. Venous blood samples were assayed for PP13 using enzyme-linked immunosorbent assay. PP13 multiples of median (MoM) were calculated and adjusted for body mass index, ethnicity, smoking, maternal age and parity. For each case of pre-eclampsia (n = 42), five controls were randomly selected. PP13 levels were compared between women who developed pre-eclampsia and controls using the Wilcoxon rank sum test. Sensitivity and false-positive rates were derived from receiver operating characteristic curves.

RESULTS

Women who developed pre-eclampsia had significantly lower (P < 0.001) PP13 MoMs compared with controls. PP13 MoMs for controls and pre-eclampsia cases were 1.0 (range 0.0-10.0) and 0.4 (range 0.0-7.0), respectively (P < 0.001). At a MoM cutoff of 0.53, for a false-positive rate of 10%, sensitivity was 50% for pre-eclampsia at term (>37 weeks), 62% for preterm pre-eclampsia (<37 weeks) and 71% for early-onset pre-eclampsia (<34 weeks).

CONCLUSION

First trimester PP13 can predict pre-eclampsia in women at increased a priori risk and predicts early-onset better than late-onset disease.

Potential markers of preeclampsia--a review

Preeclampsia is a leading cause of maternal and fetal/neonatal mortality and morbidity worldwide. The early identification of patients with an increased risk for preeclampsia is therefore one of the most important goals in obstetrics. The availability of highly sensitive and specific physiologic and biochemical markers would allow not only the detection of patients at risk but also permit a close surveillance, an exact diagnosis, timely intervention (e.g. lung maturation), as well as simplified recruitment for future studies looking at therapeutic medications and additional prospective markers. Today, several markers may offer the potential to be used, most likely in a combinatory analysis, as predictors or diagnostic tools. We present here the current knowledge on the biology of preeclampsia and review several biochemical markers which may be used to monitor preeclampsia in a future, that, we hope, is not to distant from today.

State of the art: non-invasive ultrasound assessment of the uteroplacental circulation

Impaired trophoblastic invasion of the maternal spiral arteries is associated with increased risk for subsequent development of intrauterine growth restriction, preeclampsia, and placental abruption. A series of screening studies involving assessment of impedance to flow in the uterine arteries have examined the potential value of Doppler in identifying pregnancies at risk of the complications of impaired placentation. Currently we are able to characterize uteroplacental perfusion with quantitative and qualitative methodologies. This review will examine both methodologies and seek to highlight conclusive and inconclusive findings.