ADAM12s in maternal serum as a potential marker of pre-eclampsia

Single-cell resolution of longitudinal blood transcriptome profiles in rheumatoid arthritis, systemic lupus erythematosus and healthy control pregnancies

OBJECTIVES

Comparative longitudinal analyses of cellular composition and peripheral blood gene expression in Rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and healthy pregnancies.

METHODS

In total, 335 whole blood samples from 84 RA, SLE and healthy controls before pregnancy, at each trimester, 6 weeks, 6 months and 12 months post partum were analysed. We combined bulk and single cell RNA analyses for cell-type estimation, validated by flow cytometry, before combining this in a cell-type adjusted analysis for an improved resolution of unrecognised gene expression changes associated with RA and SLE pregnancies.

RESULTS

Patients were well regulated throughout pregnancy, and few had pregnancy complications. In SLE, the interferon signature was augmented during pregnancy, and the pregnancy signature was continued post partum. An altered cell type composition strongly influences the profile. In the pregnancy signature, transcripts involved in galactosylation potentially altering the effector functions of autoantibodies became more evident. Several genes in the adjusted RA signature are expressed in mucosal associated invariant T cells.

CONCLUSION

We found distinct RA, SLE and pregnancy signatures, and no expression patterns could be attributed to medication or disease activity. Our results support the need for close postpartum follow-up of patients with SLE. Gene expression patterns in RA were closer to healthy controls than to SLE, and primarily became evident after cell-type adjustment. Adjusting for cell abundance unravelled gene expression signatures less associated with variation in cell-composition and highlighted genes with expression profiles associated with changes in specialised cell populations.

Role of ADAM and ADAMTS Disintegrin and Metalloproteinases in Normal Pregnancy and Preeclampsia

Normal pregnancy (NP) involves intricate processes starting with egg fertilization, proceeding to embryo implantation, placentation and gestation, and culminating in parturition. These pregnancy-related processes require marked uteroplacental and vascular remodeling by proteolytic enzymes and metalloproteinases. A disintegrin and metalloproteinase (ADAM) and ADAM with thrombospondin motifs (ADAMTS) are members of the zinc-dependent family of proteinases with highly conserved protein structure and sequence homology, which include a pro-domain, and a metalloproteinase, disintegrin and cysteine-rich domain. In NP, ADAMs and ADAMTS regulate sperm-egg fusion, embryo implantation, trophoblast invasion, placental angiogenesis and spiral arteries remodeling through their ectodomain proteolysis of cell surface cytokines, cadherins and growth factors as well as their adhesion with integrins and cell-cell junction proteins. Preeclampsia (PE) is a serious complication of pregnancy characterized by new-onset hypertension (HTN) in pregnancy (HTN-Preg) at or after 20 weeks of gestation, with or without proteinuria. Insufficient trophoblast invasion of the uterine wall, inadequate expansive remodeling of the spiral arteries, reduced uteroplacental perfusion pressure, and placental ischemia/hypoxia are major initiating events in the pathogenesis of PE. Placental ischemia/hypoxia increase the release of reactive oxygen species (ROS), which lead to aberrant expression/activity of certain ADAMs and ADAMTS. In PE, abnormal expression/activity of specific ADAMs and ADAMTS that function as proteolytic sheddases could alter proangiogenic and growth factors, and promote the release of antiangiogenic factors and inflammatory cytokines into the placenta and maternal circulation leading to generalized inflammation, endothelial cell injury and HTN-Preg, renal injury and proteinuria, and further decreases in uteroplacental blood flow, exaggeration of placental ischemia, and consequently fetal growth restriction. Identifying the role of ADAMs and ADAMTS in NP and PE has led to a better understanding of the underlying molecular and vascular pathways, and advanced the potential for novel biomarkers for prediction and early detection, and new approaches for the management of PE.

ADAM and ADAMTS disintegrin and metalloproteinases as major factors and molecular targets in vascular malfunction and disease

A Disintegrin and Metalloproteinase (ADAM) and A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS) are two closely related families of proteolytic enzymes. ADAMs are largely membrane-bound enzymes that act as molecular scissors or sheddases of membrane-bound proteins, growth factors, cytokines, receptors and ligands, whereas ADAMTS are mainly secreted enzymes. ADAMs have a pro-domain, and a metalloproteinase, disintegrin, cysteine-rich and transmembrane domain. Similarly, ADAMTS family members have a pro-domain, and a metalloproteinase, disintegrin, and cysteine-rich domain, but instead of a transmembrane domain they have thrombospondin motifs. Most ADAMs and ADAMTS are activated by pro-protein convertases, and can be regulated by G-protein coupled receptor agonists, Ca²⁺ ionophores and protein kinase C. Activated ADAMs and ADAMTS participate in numerous vascular processes including angiogenesis, vascular smooth muscle cell proliferation and migration, vascular cell apoptosis, cell survival, tissue repair, and wound healing. ADAMs and ADAMTS also play a role in vascular malfunction and cardiovascular diseases such as hypertension, atherosclerosis, coronary artery disease, myocardial infarction, heart failure, peripheral artery disease, and vascular aneurysm. Decreased ADAMTS13 is involved in thrombotic thrombocytopenic purpura and microangiopathies. The activity of ADAMs and ADAMTS can be regulated by endogenous tissue inhibitors of metalloproteinases and other synthetic small molecule inhibitors. ADAMs and ADAMTS can be used as diagnostic biomarkers and molecular targets in cardiovascular disease, and modulators of ADAMs and ADAMTS activity may provide potential new approaches for the management of cardiovascular disorders.

FIRST TRIMESTER SCREENING FOR PREECLAMPSIA - A SYSTEMATIC REVIEW

Objective: To increase the detection rate of preterm preeclampsia (PE) first trimester combined screening tests are being developed. The aim of this review is to create an overview of the currently investigated screening markers, algorithms and their validations.Methods: Comprehensive review of the literature concerning first trimester screening for PEResults and conclusions: Studies investigating a total of 160 biochemical, 6 biophysical and 14 ultrasound markers could be identified. Of the 21 algorithms published, mainly the algorithm published by the Fetal Medicine Foundation London has been validated. This algorithm performes significantly better than screening by anamnestic risk factors only.

Preeclampsia and the challenge of early prediction: reality or utopia? State of art and critical review of literature

Purpose: The challenge to obtain improved predictive tools, able to identify women destined to develop preeclampsia (PE), is raising the interest of researchers for the attractive chance to allow for timely initiation of prophylactic therapy, appropriate antenatal surveillance, and better-targeted research into preventive interventions. We aimed to gather all the evidence reported up to now in scientific literature relating to all prediction tests for PE.Materials and methods: We searched articles on conventional literature platforms from January 1952 to August 2016, using the terms "preeclampsia," "gestational preeclampsia," and "gestational hypertensive disorders" combined with "predictive test" and "risk assessment." Abstracts/titles identified by the search were screened by three investigators.Results: The search identified 203 citations, of which 154 potentially relevant after the initial evaluation. Among these studies, 20 full articles were excluded, therefore, 134 primary studies met the criteria for inclusion and were analyzed.Conclusions: Current evidence suggests that a combination of several features may provide the best predictive accuracy for the identification of PE. Large-scale, multicenter, multiethnic, prospective trials are required to propose an ideal combination of markers for routine screening.

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.

Preeclampsia biomarkers: An assessment of maternal cardiometabolic health

Preeclampsia is a serious pregnancy condition defined as new-onset hypertension and proteinuria, commonly characterized as either early, 'placental', or late onset, 'maternal', using a cut-off of 34 weeks gestation. However, it may be more useful to differentiate between the vascular remodelling and placental invasion vs. inflammation and metabolic pathophysiology that underlie these forms of preeclampsia. Due to rising rates of obesity, the late-onset, maternal form is increasingly occurring earlier in pregnancy. Predictive tests for preeclampsia typically include biophysical markers such as maternal body mass index and mean arterial pressure, indicating the importance of cardiovascular and metabolic health in its pathophysiology. In contrast, the placental, inflammatory, endothelial and/or metabolic biomarkers used in these tests are generally thought to indicate an abnormal response to placentation and predict the disease. However, many of these non-placental biomarkers are known to predict impaired metabolic health in non-pregnant subjects with obesity (metabolically unhealthy obesity) and coronary artery disease or stroke in people at risk for cardiovascular events. Similarities between the performance of these markers in the prediction of cardiovascular and metabolic health outside of pregnancy suggests that they may be more indicative of maternal health than predictive for preeclampsia. This paper reviews the biophysical and biochemical markers in preeclampsia prediction and compares their performance to tests assessing metabolic health and risk of cardiovascular disease, particularly in the obese population.

First trimester maternal serum analytes and second trimester uterine artery Doppler in the prediction of preeclampsia and fetal growth restriction

OBJECTIVE

This study aimed to determine whether pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin (β-hCG), a disintegrin and metalloprotease 12 (ADAM12), and placenta protein 13 (PP13) in the first trimester, and uterine artery Doppler (UAD) in the second trimester, predict preeclampsia and fetal growth restriction (FGR).

MATERIALS AND METHODS

Maternal serum levels of PAPP-A, free β-hCG, ADAM12, and PP13 at 11-13⁺⁶ weeks of gestation and bilateral uterine artery pulsatility index (PI) at 22-24 weeks of gestation were measured in a nested case-control study within a prospective cohort. The serum analytes and Doppler measurements were compared for uncomplicated pregnancies and pregnancies complicated by preeclampsia and FGR. The efficacy of biochemical and Doppler measurements for the prediction of preelampsia and FGR was investigated.

RESULTS

Compared with gestational age-matched controls (n = 200), the mean PAPP-A and ADAM12 were lower (P < 0.001, P < 0.05) in pregnancies complicated by preeclampsia (n = 462) and FGR (n = 350). The median uterine artery mean PI was higher (P < 0.001) in preeclampsia and FGR groups. However, the median free β-hCG and PP13 were not significantly different from normal (P > 0.05). In screening for preeclampsia and FGR, assuming a fixed false positive rate (FPR) of 10%, the detection rates were 72% and 68% for a combination of PAPP-A, ADAM12, and UAD, respectively.

CONCLUSION

First trimester PAPP-A and ADAM12 levels and second trimester uterine artery PI are associated with adverse pregnancy outcomes. The combination of biochemical markers and UAD improves the screening efficiency for the prediction of preeclampsia and FGR.

Prediction and prevention of pre-eclampsia in Asian subpopulation

The benefit of the early administration of aspirin to reduce preterm pre-eclampsia among screened positive European women from multivariate algorithmic approach (ASPRE trial) has opened an intense debate on the feasibility of universal screening. This review aims to assess the new perspectives in the combined screening of pre-eclampsia in the first trimester of pregnancy and the chances for prevention using low-dose aspirin with special emphasis on the particularities of the Asian population. PubMed, CENTRAL and Embase databases were searched from inception until 15 November 2017 using combinations of the search terms: preeclampsia, Asian, prenatal screening, early prediction, ultrasonography, pregnancy, biomarker, mean arterial pressure, soluble fms-like tyrosine kinase-1, placental growth factor, pregnancy-associated plasma protein-A and pulsatility index. This is not a systematic review or meta-analysis, so the risk of bias of the selected published articles and heterogeneity among the studies need to be considered. The prevalence of pre-eclampsia and serum levels of biochemical markers in Asian are different from Caucasian women; hence, Asian ethnicity needs to be corrected for in the algorithmic assessment of multiple variables to improve the screening performance. Aspirin prophylaxis may still be viable in Asian women, but resource implication needs to be considered. Asian ethnicity should be taken into account before implementing pre-eclampsia screening strategies in the region. The variables included can be mixed and matched to achieve an optimal performance that is appropriate for economical restriction in individual countries.

The core transcriptome of mammalian placentas and the divergence of expression with placental shape

INTRODUCTION

The placenta is arguably the most anatomically variable organ in mammals even though its primary function is conserved.

METHOD

Using RNA-Seq, we measured the expression profiles of 55 term placentas of 14 species of mammals representing all major eutherian superordinal clades and marsupials, and compared the evolution of expression across clades.

RESULTS

We identified a set of 115 core genes which is expressed (FPKM ≥10) in all eutherian placentas, including genes with immune-modulating properties (ANXA2, ANXA1, S100A11, S100A10, and LGALS1), cell-cell interactions (LAMC1, LUM, and LGALS1), invasion (GRB2 and RALB) and syncytialization (ANXA5 and ANXA1). We also identified multiple pre-eclampsia associated genes which are differentially expressed in Homo sapiens when compared to the other 13 species. Multiple genes are significantly associated with placenta morphology, including EREG and WNT5A which are both associated with placental shape.

DISCUSSION

115 genes are important for the core functions of the placenta in all eutherian species analyzed. The molecular functions and pathways enriched in the core placenta align with the evolutionarily conserved functionality of the placenta.

Matrix metalloproteinase multiplex screening identifies increased MMP-2 urine concentrations in women predicted to develop preeclampsia

BACKGROUND

Preeclampsia, a pregnancy disorder characterized by hypertension and proteinuria, represents the leading cause of fetal and maternal morbidity and mortality in developing countries. The identification of novel and accurate biomarkers that are predictive of preeclampsia is necessary to improve the prognosis of patients with preeclampsia.

OBJECTIVE

The objective of this study is to evaluate the usefulness of nine urinary metalloproteinases to predict the risk of preeclampsia development.

METHODS

MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-12 and MMP-13 were analyzed in urine (early-pregnancy) from 17 women predicted to develop preeclampsia and 48 controls using the Bio-Plex Pro-Human MMP panel (Bio-Rad, Hercules, CA).

RESULTS

Urinary MMP-2 showed differences between groups which allowed us to calculate an increased risk for PE development of up to 20 times among the study population.

CONCLUSION

Increased urinary concentration of MMP-2 at 12 and 16 weeks of gestation predicted an increased risk of developing preeclampsia in the study population.

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.

Validation of serum biomarkers derived from proteomic analysis for the early screening of preeclampsia

AIM

To examine the potential value of previously identified biomarkers using proteomics in early screening for preeclampsia (PE).

METHODS

24 blood samples from women who subsequently developed PE and 48 from uncomplicated pregnancies were obtained at 11-13 weeks and analysed after delivery. Cystatin-C, sVCAM-1, and Pappalysin-1 were quantified by ELISA. Maternal characteristics and medical history were recorded.

RESULTS

Median values of Cystatin-C, sVCAM-1, and Pappalysin-1 in the PE group as compared to controls were 909.1 gEq/mL versus 480.0 gEq/mL, P = .000, 832.0 gEq/mL versus 738.8 gEq/mL, P = .024, and 234.4 gEq/mL versus 74.9 gEq/mL, P = .064, respectively. Areas under the receiver-operating characteristic curves (AUC, standard error (SE)) for predicting PE were Cystatin-C: 0.90 (SE 0.04), VCAM-1: 0.66 (SE 0.074), and Pappalysin-1: 0.63 (SE 0.083). To discriminate between cases at risk for PE and normal controls, cut-off values of 546.8 gEq/mL for Cystatin-C, 1059.5 gEq/mL for sVCAM-1, and 220.8 gEq/mL for Pappalysin-1 were chosen, providing sensitivity of 91%, 41%, and 54% and specificity of 85%, 100%, and 95%, respectively.

CONCLUSIONS

sVCAM-1 and Pappalysin-1 do not improve early screening for PE. Cystatin-C, however, seems to be associated with subsequent PE development, but larger studies are necessary to validate these findings.

Development and validation of a risk factor scoring system for first-trimester prediction of preeclampsia

OBJECTIVE

The aim of this study was to develop a multiparameter risk-based scoring system for first-trimester prediction of preeclampsia and to validate this scoring system in our patient population.

STUDY DESIGN

Secondary analysis of a prospective cohort of 1,200 patients presenting for first-trimester aneuploidy screening. Maternal serum pregnancy-associated plasma protein A (PAPP-A) levels were measured and bilateral uterine artery (UA) Doppler studies performed. Using the first half of the study population, a prediction model for preeclampsia was created. Test performance characteristics were used to determine the optimal score for predicting preeclampsia. This model was then validated in the second half of the population.

RESULTS

Significant risk factors and their weighted scores derived from the prediction model were chronic hypertension (4), history of preeclampsia (3), pregestational diabetes (2), body mass index ≥ 30 kg/m(2) (2), bilateral UA notching (1), and PAPP-A MoM < 10 th percentile (1). The area under the curve (AUC) for the risk scoring system was 0.76 (95% confidence interval [CI], 0.69-0.83), and the optimal threshold for predicting preeclampsia was a total score of ≥ 6. This AUC did not differ significantly from the AUC observed in our validation cohort (AUC, 0.78 [95% CI, 0.69-0.86]; p = 0.75].

CONCLUSION

Our proposed risk factor scoring system demonstrates modest accuracy but excellent reproducibility for first-trimester prediction of preeclampsia.

Mid-trimester maternal ADAM12 levels differ according to fetal gender in pregnancies complicated by preeclampsia

An overrepresentation of adverse pregnancy outcomes has been observed in pregnancies associated with a male fetus. We investigated the association between fetal gender and candidate biomarkers for preeclampsia. Proteins were quantified in samples taken at 20 weeks from women recruited to the SCreening fOr Pregnancy Endpoints (SCOPE) study (preeclampsia n = 150; no preeclampsia n = 450). In contrast to placental growth factor, soluble endoglin, and insulin-like growth factor acid labile subunit, levels of metallopeptidase domain 12 (ADAM12) at 20 weeks were dependent on fetal gender in pregnancies complicated by preeclampsia, for male (n = 73) fetuses the multiples of the median (MoM; interquartile range [IQR] 1.1-1.5) was 1.3, whereas for female fetuses (n = 75) MoM was 1.1 (1.0-1.3); P < .01. Prediction of preeclampsia using ADAM12 levels was improved for pregnancies associated with a male fetus (area under receiver-operator curve [AUC] 0.73 [95% confidence interval [CI] 0.67-0.80]) than that of a female fetus (AUC 0.62 [0.55-0.70]); P = .03. The data presented here fit a contemporary hypothesis that there is a difference between the genders in response to an adverse maternal environment and suggest that an alteration in ADAM12 may reflect an altered placental response in pregnancies subsequently complicated by preeclampsia.

Pregnancy-associated plasma protein A (PAPP-A) and preeclampsia

Pregnancy-associated plasma protein A (PAPP-A) is a key regulator of insulin-like growth factor bioavailability essential for normal fetal development. In maternal blood, this protein increases with gestational age and then rapidly decreases after delivery. It is routinely used for Down syndrome screening in the first trimester of pregnancy, and its decrease compared to a normal pregnancy indicates an increased risk for both chromosomal anomalies and adverse pregnancy outcomes. It belongs to a group of biomarkers that predict later preeclampsia development, primarily early onset preeclampsia; however, it should be combined with a Doppler ultrasonography of the uterine artery (pulsatile index) and other biochemical and maternal factors to achieve a higher detection rate with an acceptable false positivity rate. Some studies have demonstrated an even more pronounced decrease of PAPP-A in the early second trimester of pregnancy in women who subsequently develop preeclampsia compared with women who do not develop preeclampsia. Conversely, during the last trimester of pregnancy, its concentration increases even more in patients with preeclampsia than in patients without. It is also detectable at very low levels in nonpregnant individuals, and a higher concentration indicates an adverse effect in patients with acute coronary syndromes or stable atherosclerotic disease and in patients with end-stage renal disease who are being treated with hemodialysis.

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.

Efficiency of first-trimester uterine artery Doppler, a-disintegrin and metalloprotease 12, pregnancy-associated plasma protein a, and maternal characteristics in the prediction of preeclampsia

OBJECTIVES

The purpose of this study was to estimate the efficiency of first-trimester uterine artery Doppler, A-disintegrin and metalloprotease 12 (ADAM12), pregnancy-associated plasma protein A (PAPP-A), and maternal characteristics in the prediction of preeclampsia.

METHODS

We conducted a prospective cohort study of patients presenting for first-trimester aneuploidy screening between 11 and 14 weeks' gestation. Maternal serum ADAM12 and PAPP-A levels were measured by an immunoassay, and mean uterine artery Doppler pulsatility indices were calculated. Outcomes of interest included preeclampsia, early preeclampsia (defined as requiring delivery at <34 weeks' gestation), and gestational hypertension. Logistic regression analysis was used to model the prediction of preeclampsia using ADAM12 multiples of the median (MoM), PAPP-A MoM, and uterine artery Doppler pulsatility index MoM, either individually or in combination. The sensitivity, specificity, and area under the receiver operating characteristic curves were used to compare the screening efficiency of the models using nonparametric U statistics.

RESULTS

Among 578 patients with complete outcome data, there were 54 cases of preeclampsia (9.3%) and 13 cases of early preeclampsia (2.2%). Median ADAM12 levels were significantly lower in patients who developed preeclampsia compared to those who did not (0.81 versus 1.01 MoM; P = .04). For a fixed false-positive rate of 10%, ADAM12, PAPP-A, and uterine artery Doppler parameters in combination with maternal characteristics identified 50%, 48%, and 52% of patients who developed preeclampsia, respectively. Combining these first-trimester parameters did not improve the predictive efficiency of the models.

CONCLUSIONS

First-trimester ADAM12, PAPP-A, and uterine artery Doppler characteristics are not sufficiently predictive of preeclampsia. Combinations of these parameters do not further improve their screening efficiency.

Ectopic pregnancy: a review

PURPOSE

Ectopic pregnancy (EP) presents a major health problem for women of child-bearing age. EP refers to the pregnancy occurring outside the uterine cavity that constitutes 1.2-1.4 % of all reported pregnancies. All identified risk factors are maternal: pelvic inflammatory disease, Chlamydia trachomatis infection, smoking, tubal surgery, induced conception cycle, and endometriosis. These developments have provided the atmosphere for trials using methotrexate as a non-surgical treatment for EP. The diagnosis measure of EP is serum human chorionic gonadotropin, urinary hCGRP/i-hCG, progesterone measurement, transvaginal ultrasound scan, computed tomography, vascular endothelial growth factor, CK, disintegrin and metalloprotease-12 and hysterosalpingography. The treatment option of EP involves surgical treatment by laparotomy or laparoscopy, medical treatment is usually systemic or through local route, or by expectant treatment.

RESULTS

It was concluded that review data reflect a decrease in surgical treatment and not an actual decline in EP occurrence so that further new avenues are needed to explore early detection of the EP.

A disintegrin and metalloproteinase-12 (ADAM12): function, roles in disease progression, and clinical implications

BACKGROUND

A disintegrin and metalloproteinase-12 (ADAM12) is a member of the greater ADAM family of enzymes: these are multifunctional, generally membrane-bound, zinc proteases for which there are forty genes known (21 of these appearing in humans). ADAM12 has been implicated in the pathogenesis of various cancers, liver fibrogenesis, hypertension, and asthma, and its elevation or decrease in human serum has been linked to these and other physiological/pathological conditions.

SCOPE

In this review, we begin with a brief overview of the ADAM family of enzymes and protein structure. We then discuss the role of ADAM12 in the progression and/or diagnosis of various disease conditions, and we will conclude with an exploration of currently known natural and synthetic inhibitors.

MAJOR CONCLUSION

ADAM12 has potential to emerge as a successful drug target, although targeting the metalloproteinase domain with any specificity will be difficult to achieve due to structural similarity between the members of the ADAM and MMP family of enzymes. Overall, more research is required to establish ADAM12 being as a highly desirable biomarker and drug target of different diseases, and their selective inhibitors as potential therapeutic agents.

GENERAL SIGNIFICANCE

Given the appearance of elevated levels of ADAM12 in various diseases, particularly breast cancer, our understanding of this enzyme both as a biomarker and a potential drug target could help make significant inroads into both early diagnosis and treatment of disease.

RASSF1A in maternal plasma as a molecular marker of preeclampsia

OBJECTIVES

This study aimed to quantitate cell free (cf) and cell free fetal (cff) DNA in maternal plasma by determining RASSF1A levels before and after enzyme digestion in women who subsequently developed preeclampsia (PE) and compare them with uncomplicated pregnancies.

METHODS

Twenty-four samples from pregnant women who developed PE and 48 samples from women with uncomplicated pregnancies were analysed. Blood samples were obtained at 11-13 weeks. cfDNA was determined by quantifying RASSF1A using qRT-PCR. A second qRT-PCR was performed following methylation-sensitive enzyme digestion by BstUI, to quantitate hypermethylated RASSF1A sequences of fetal origin. ACTB gene was used as control to confirm complete enzyme digestion.

RESULTS

cfDNA and cffDNA levels were significantly increased in women who developed PE as compared with uncomplicated pregnancies (median cfDNA: 9402 vs 2698, median cffDNA: 934.5 vs 62, respectively). Following operating characteristic curve analysis, cut-off values of 7486 Εq/mL for cfDNA and 512 Εq/mL for cffDNA were chosen, which provided a sensitivity of 75% and 100% and specificity of 98% and 100%, respectively, to identify women at risk for PE.

CONCLUSIONS

The study demonstrates potential use of cfDNA and cffDNA in maternal plasma as markers for the early prediction of women at risk for PE.

Predictive Value of Maternal Serum Markers for Preeclampsia

<p>The study performed a systematic review of screening for preeclampsia with the combination of vascular parameters and maternal serum markers in the first and early second trimester. We identified eligible studies through a search of Medline, and, for each included study, we focused on the relationship between the maternal serum markers and preeclampsia. In the selected literature, a combination of maternal serum markers was analyzed, also. Several tests suggested moderate or convincing prediction of early preeclampsia, but screening for late preeclampsia was poor. Literatures for serum markers were selected. Each serum marker was identified independently, and where relevant, a combination of these markers was analyzed. Encouraging results for the first trimester screening were observed when it was combined with other markers. Even in the first trimester of pregnancy, we can present the reliable results for the prediction of early preeclampsia. Detection rate for combination markers may yield higher detection rate and be promising to identify patients at high risk of developing preeclampsia.</p>

First-trimester prediction of preeclampsia in nulliparous women at low risk

OBJECTIVE

To identify clinical characteristics and biochemical markers in first-trimester samples that would possibly predict the subsequent development of preeclampsia.

METHODS

We conducted a multicenter observational study in 2,434 nulliparous women at low risk to identify biomarkers that possibly predict preeclampsia. Clinical history, complete blood count, and biochemical markers were assessed in the first trimester. The trophoblast and angiogenesis markers ADAM-12, pregnancy-associated plasma protein-A, placental protein 13, placental growth factor, soluble fms-like tyrosine kinase-1, and endoglin were measured in a case-control subset of 174 women with preeclampsia and 509 women in the control group.

RESULTS

Univariable analysis revealed maternal age, race, marital status, years of education, source of medical payment, prenatal caregiver, body mass index (BMI, calculated as weight (kg)/[height (m)]), and systolic blood pressure at enrollment were significantly associated with preeclampsia. Mean platelet volume was greater at enrollment in women who later had development of preeclampsia (median 9.4 compared with 9.0 femtoliter (fl); P=.02). First-trimester concentrations (multiples of the median) of ADAM-12 (1.14 compared with 1.04; P=.003), pregnancy-associated plasma protein-A (0.94 compared with 0.98; P=.04), and placental growth factor (0.83 compared with 1.04; P<.001) were significantly different in women who had development of preeclampsia compared with women in the control group. The optimal multivariable model included African American race, systolic blood pressure, BMI, education level, ADAM-12, pregnancy-associated plasma protein-A, and placental growth factor, and yielded an area under the curve of 0.73 (95% confidence interval 0.69-0.77) and a sensitivity of 46.1% (95% confidence interval 38.3-54.0) for 80% specificity.

CONCLUSION

A multivariable analysis of clinical data and biochemical markers in the first trimester did not identify a model that had clinical utility for predicting preeclampsia in a nulliparous population at low risk.

LEVEL OF EVIDENCE

II.

Quantitative proteomic (iTRAQ) analysis of 1st trimester maternal plasma samples in pregnancies at risk for preeclampsia

A current major obstacle is that no reliable screening markers exist to detect pregnancies at risk for preeclampsia. Quantitative proteomic analysis employing isobaric labelling (iTRAQ) has been suggested to be suitable for the detection of potential plasma biomarkers, a feature we recently verified in analysis of pregnancies with Down syndrome foetuses. We have now examined whether this approach could yield biomarkers to screen pregnancies at risk for preeclampsia. In our study, we used maternal plasma samples obtained at 12 weeks of gestation, six from women who subsequently developed preeclampsia and six with uncomplicated deliveries. In our analysis, we observed elevations in 10 proteins out of 64 proteins in the preeclampsia study group when compared to the healthy control group. These proteins included clusterin, fibrinogen, fibronectin, and angiotensinogen, increased levels of which are known to be associated with preeclampsia. An elevation in the immune-modulatory molecule, galectin 3 binding protein, was also noted. Our pilot study, therefore, indicates that quantitative proteomic iTRAQ analysis could be a useful tool for the detection of new preeclampsia screening markers.

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.

Evaluation of 7 serum biomarkers and uterine artery Doppler ultrasound for first-trimester prediction of preeclampsia: a systematic review

Preeclampsia (PE) affects 1% to 2% of pregnant women and is a leading cause of maternal and perinatal morbidity and mortality worldwide. The clinical syndrome of PE arises in the second half of pregnancy. However, many underlying factors including defective placentation may already be apparent in the first and early second trimester in many patients. In clinical practice, there is currently no reliable screening method in the first trimester of pregnancy with sufficient accuracy to identify women at high risk to develop PE. Early identification of high-risk pregnancy may facilitate the development of new strategies for antenatal surveillance or prevention and thus improve maternal and perinatal outcome. The aim of this systematic review was to study the literature on the predictive potential of first-trimester serum markers and of uterine artery Doppler velocity waveform assessment (Ut-A Doppler). Literature on the 7 most studied serum markers (ADAM12, fβ-hCG, Inhibin A, Activin A, PP13, PlGF, and PAPP-A) and Ut-A Doppler was primarily selected. In the selected literature, a combination of these markers was analyzed, and where relevant, the value of maternal characteristics was added. Measurements of serum markers and Ut-A Doppler were performed between week 8 + 0 and 14 + 0 GA. Low levels of PP13, PlGF, and PAPP-A and elevated level of Inhibin A have been found to be significantly associated with the development of PE later in pregnancy. The detection rates of single markers, fixed at 10% false-positive rate, in the prediction of early-onset PE were relatively low, and ranged from 22% to 83%. Detection rates for combinations of multiple markers varied between 38% and 100%. Therefore, a combination of multiple markers yields high detection rates and is promising to identify patients at high risk of developing PE. However, large scale prospective studies are required to evaluate the power of this integrated approach in clinical practice.

TARGET AUDIENCE

Obstetricians and Gynecologists, Family physicians Learning Objectives: After completion of this article, the reader should be better able to appraise the recent literature on the development of preeclampsia in the first-trimester, evaluate the predictive value of first-trimester markers and use first-trimester markers, either individually or in combination, to assess the risk of preeclampsia.

Screening for pre-eclampsia--lessons from aneuploidy screening

BACKGROUND

Antenatal screening for aneuploidy is an established routine clinical practice worldwide. The same statistical methodology, developed and refined over three decades, might be adapted to screening for pre-eclampsia.

METHODS

The published literature is reviewed for evidence that the methodology is valid for pre-eclampsia using first trimester maternal serum PP13, PAPP-A, PlGF, ADAM12 and inhibin A, together with MAP and uterine artery Doppler PI. Risk is estimated for both early onset pre-eclampsia, requiring delivery before 34 weeks, or late onset disease. Prior risk from the background prevalence multiplied by likelihood ratios (LRs) for ethnicity, parity, adiposity and family history is multiplied by an LR from the screening marker profile. Markers are expressed in multiples of the gestation-specific median and adjusted for body mass, ethnicity and smoking status as appropriate. A standardized population with a fixed distribution of risk factors and a multi-variate Gaussian model of marker profiles is used to predict performance.

RESULTS

There is sufficient published data to estimate individual risks reasonably well. Modeling predicts that using PAPP-A and one other serum marker, together with the physical markers more than two-thirds of early and one-third of late onset cases can be detected by classifying less than 2% of pregnancies as high risk; three-quarters of early case could be detected with a 5% high risk rate.

CONCLUSION

Whilst more data on some markers is still required modeling so far suggests that extending first trimester aneuploidy screening programs to include pre-eclampsia screening would yield a high detection. However, prospective studies are needed to verify the model predictions.

Von Willebrand factor and ADAMTS13: a candidate couple for preeclampsia pathophysiology

OBJECTIVE

The goal of this study was to search for an association between a desintegrin-like and metalloprotease thrombospondin type 1 motif, member 13 (ADAMTS13) levels and the occurrence of preeclampsia, its characteristics (time-onset and severity), and its consequences (occurrence of fetal growth restriction or preterm delivery).

METHODS AND RESULTS

We studied 140 pairs of women in a case-control study with 3 matching criteria: maternal age, gestational age, and ethnic origin. We measured ADAMTS13 activity using a fluorescence resonance energy transfer assay with the fluorescence resonance energy transfer-VWF73 peptide. ELISA was used to assess protein antigen levels: ADAMTS13, von Willebrand Factor (VWF), interleukin-6, C-reactive protein, P-selectin, and thrombospondin-1. The lowest levels of ADAMTS13 (activity ≤ 70% or antigen ≤ 592 ng/mL) were significantly associated with preeclampsia (odds ratios [OR] [95% confidence interval] of 4.2 [1.1 to 15] and 14.3 [1.7 to 123], respectively). This association was independent of VWF levels and preeclampsia risk factors but dependent on interleukin-6 and C-reactive protein levels for ADAMTS13 activity. Levels of ADAMTS13 activity (≤ 57%) were significantly associated with early-onset preeclampsia (OR = 2.5 [1.1 to 5.8]). Severe preeclampsia was associated with the highest levels of P-selectin (>57 ng/mL) (OR = 3.4 [1.2 to 9.7]).

CONCLUSIONS

Preeclampsia is associated with decreased levels of ADAMTS13, independently of VWF. This decrease is quantitative, occurs early, and seems to be dependent on inflammation. Our results suggest that ADAMTS13 could participate in the pathophysiology of preeclampsia.

Regulation of pregnancy-associated plasma protein A2 (PAPPA2) in a human placental trophoblast cell line (BeWo)

BACKGROUND

Pregnancy-associated plasma protein A2 (PAPPA2) is an insulin-like growth factor-binding protein (IGFBP) protease expressed at high levels in the placenta and upregulated in pregnancies complicated by preeclampsia and HELLP (Hemolytic anemia, Elevated Liver enzymes, and Low Platelet count) syndrome. However, it is unclear whether elevated PAPPA2 expression causes abnormal placental development, or whether upregulation compensates for placental pathology. In the present study, we investigate whether PAPPA2 expression is affected by hypoxia, oxidative stress, syncytialization factors or substances known to affect the expression of PAPPA2's paralogue, PAPPA.

METHODS

BeWo cells, a model of placental trophoblasts, were treated with one of the following: hypoxia (2% O2), oxidative stress (20 microM hydrogen peroxide), forskolin (10 microM and 100 microM), TGF-beta (10 and 50 ng/mL), TNF-alpha (100 ng/mL), IL-1beta (100 ng/mL) or PGE2 (1 microM). We used quantitative RT-PCR (qRT-PCR) to quantify the mRNA levels of PAPPA2, as well as those of PAPPA and ADAM12 since these proteases have similar substrates and are also highly expressed in the placenta. Where we observed significant effects on PAPPA2 mRNA levels, we tested for effects at the protein level using an in-cell Western assay.

RESULTS

Hypoxia, but not oxidative stress, caused a 47-fold increase in PAPPA2 mRNA expression, while TNF-alpha resulted in a 6-fold increase, and both of these effects were confirmed at the protein level. PGE2 resulted in a 14-fold upregulation of PAPPA2 mRNA but this was not reflected at the protein level. Forskolin, TGF-beta and IL-1beta had no significant effect on PAPPA2 mRNA expression. We observed no effects of any treatment on PAPPA or ADAM12 expression.

CONCLUSION

Our study demonstrates that factors previously known to be highly expressed in preeclamptic placentae (PGE2 and TNF-alpha), contribute to the upregulation of PAPPA2. Hypoxia, known to occur in preeclamptic placentae, also increased PAPPA2 expression. These results are consistent with the hypothesis that PAPPA2 is upregulated as a consequence of placental pathology, rather than elevated PAPPA2 levels being a cause of preeclampsia.

A disintegrin and metalloprotease protein-12 as a novel marker for the diagnosis of ectopic pregnancy

OBJECTIVE

To evaluate the performance of a novel biomarker, a disintegrin and metalloprotease-12 (ADAM-12), to differentiate an ectopic pregnancy (EP) from normal intrauterine pregnancies (IUPs).

DESIGN

Case-control study.

SETTING

Three urban academic centers.

PATIENT(S)

Women who were seen in the emergency department with pain or bleeding in the first trimester of pregnancy.

INTERVENTION(S)

Sera from women with diagnosed EP or IUP were evaluated via proteomics and an ADAM-12 dissociation-enhanced lanthanide fluoroimmunoassay.

MAIN OUTCOME MEASURE(S)

Differences between groups, area under the receiver operating curve, sensitivity, and specificity.

RESULT(S)

Via a proteomics evaluation, we found a statistically significant decrease in ADAM-12 in the sera of patients with EP, which we confirmed in a larger group of 199 patients (median IUP 18.6 ng/mL versus median EP 2.5 ng/mL with good discrimination between the groups as assessed by receiver operating characteristics [area under the curve = 0.82]). At a low cut-point, the sensitivity was 70% and specificity 84%, but, at a higher cut-point optimizing sensitivity, the ADAM-12 test demonstrated a sensitivity of 97%.

CONCLUSION(S)

ADAM-12 is a promising marker for the diagnosis of EP in women with symptoms in the first trimester, validating the proteomics findings. Further studies in additional patient populations and in combination with other biomarkers are needed.

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.

First-trimester serum analytes, biophysical tests and the association with pathological morphometry in the placenta of pregnancies with preeclampsia and fetal growth restriction

OBJECTIVE

We test the hypothesis that first-trimester serum analytes, 4-D power Doppler placental vascular indices and uterine artery Doppler (UAD) predicts abnormal placental morphometry in pregnancies with preeclampsia (PE) and fetal growth restriction (FGR).

STUDY DESIGN

Maternal serum analytes (PAPP-A, hCG, ADAM12s, and PP13), bilateral UADs, and placental vascular indices were measured at 11-14 weeks in a nested-case control study within a prospective cohort of women followed from the first-trimester to delivery. Vascularization index (VI), flow index (FI), and vascularization flow index (VFI) were obtained from 4-D power Doppler histograms. Serum analytes were measured using immunofluorometric assays and values converted to multiples of the median (MoM) for gestational age. Morphometric analysis was performed on placentas from pregnancies complicated by PE (n = 13), gestational hypertension (HBP, n = 7) and FGR (defined as fetal weight <10th percentile with abnormal umbilical artery Doppler: n = 7); and 20 uncomplicated pregnancies. Two pregnancies had both FGR and PE. Each placenta was weighed and random samples taken, and fixed in formalin within 1 h of delivery. Hematoxylin & Eosin stained slides were analyzed by design-based stereology to quantify linear dimensions, surface areas and volumes of placental components. Paired t-test and ANOVA with adjustments for multiple comparisons were used.

RESULTS

The surface areas of terminal and intermediate villi as well as the volume of terminal villi were significantly smaller in placentas from pregnancies complicated by FGR and PE. Compared with the control group the mean PAPP-A (MoM) was lower in the pregnancies with abnormal placenta morphometry (1.1 ± 0.5 versus 0.7 ± 0.5, P = 0.03). The morphometric indices were lower in those pregnancies with low PAPP-A and IUGR compared with preeclampsia.

CONCLUSION

First-trimester PAPP-A levels are associated with abnormal placental morphometry at delivery in pregnancies with PE and IUGR. These findings may explain the association between adverse pregnancy outcomes and first-trimester PAPP-A.

Molecular and vascular targets in the pathogenesis and management of the hypertension associated with preeclampsia

Normal pregnancy is associated with significant hemodynamic changes and vasodilation of the uterine and systemic circulation in order to meet the metabolic demands of the mother and developing fetus. Preeclampsia (PE) is one of the foremost complications of pregnancy and a major cause of maternal and fetal mortality. The pathophysiological mechanisms of PE have been elusive, but some parts of the puzzle have begun to unravel. Genetic factors such as leptin gene polymorphism, environmental and dietary factors such as Ca(2+) and vitamin D deficiency, and co-morbidities such as obesity and diabetes may increase the susceptibility of pregnant women to develop PE. An altered maternal immune response may also play a role in the development of PE. Although the pathophysiology of PE is unclear, most studies have implicated inadequate invasion of cytotrophoblasts into the uterine artery, leading to reduced uteroplacental perfusion pressure (RUPP) and placental ischemia/hypoxia. Placental ischemia induces the release of biologically active factors such as growth factor inhibitors, anti-angiogenic factors, inflammatory cytokines, reactive oxygen species, hypoxia-inducible factors, and antibodies to vascular angiotensin II (AngII) receptor. These bioactive factors could cause vascular endotheliosis and consequent increase in vascular resistance and blood pressure, as well as glomerular endotheliosis with consequent proteinuria. The PE-associated vascular endotheliosis could be manifested as decreased vasodilator mediators such as nitric oxide, prostacyclin and hyperpolarizing factor and increased vasoconstrictor mediators such as endothelin-1, AngII and thromboxane A₂. PE could also involve enhanced mechanisms of vascular smooth muscle contraction including intracellular Ca(2+), and Ca(2+) sensitization pathways such as protein kinase C and Rho-kinase. PE-associated changes in the extracellular matrix composition and matrix metalloproteinases activity also promote vascular remodeling and further vasoconstriction in the uterine and systemic circulation. Some of these biologically active factors and vascular mediators have been proposed as biomarkers for early prediction or diagnosis of PE, and as potential targets for prevention or treatment of the disease.

First-trimester placental protein 13 and placental growth factor: markers for identification of women destined to develop early-onset pre-eclampsia

OBJECTIVE

 To investigate the predictive value of maternal serum pregnancy-associated plasma protein A (PAPP-A), free β subunit of human chorionic gonadotrophin (fβ-hCG), placental protein 13 (PP13), placental growth factor (PlGF) and a desintegrin and metalloproteinase 12 (ADAM12), for first-trimester identification of early-onset pre-eclampsia.

DESIGN

  Nested case-control study.

SETTING

  Routine first-trimester screening for trisomy 21 in the Netherlands.

POPULATION

  Eighty-eight women who developed pre-eclampsia or haemolysis, elevated liver enzymes, low platelets (HELLP) syndrome before 34 weeks of gestation and 480 controls.

METHODS

  PP13, PlGF and ADAM12 were measured in stored first-trimester serum, previously tested for PAPP-A and fβ-hCG. All marker levels were expressed in multiples of the gestation-specific normal median (MoMs). Model predicted detection rates for fixed false-positive rates were obtained for statistically significant markers alone and in combination.

MAIN OUTCOME MEASURES

  Development of pre-eclampsia or HELLP syndrome.

RESULTS

 PP13 and PlGF were reduced in women with pre-eclampsia, with medians 0.68 MoM and 0.73 MoM respectively (P < 0.0001 for both). PAPP-A was reduced (median 0.82 MoM, P < 0.02) whereas ADAM12 and fβ-hCG did not differ between control women and those with pre-eclampsia. In pre-eclampsia complicated by a small-for-gestational-age fetus, all markers except fβ-hCG had lower values, compared with pregnancies involving fetuses of normal weight. The model-predicted pre-eclampsia detection rate for a combination of PP13 and PlGF was 44% and 54%, respectively, for a fixed 5% and 10% false-positive rate.

CONCLUSION

 This study demonstrates that PP13 and PlGF in the first-trimester might be promising markers in risk assessment for early pre-eclampsia/HELLP syndrome but for an adequate screening test additional characteristics are necessary.

Altered levels of insulin-like growth factor binding protein proteases in preeclampsia and intrauterine growth restriction

Intrauterine growth restriction (IUGR) and preeclampsia (PE) are leading causes of perinatal and maternal morbidity and mortality. Many studies have found association between low levels of insulin-like growth factor binding protein (IGFBP) proteases in the first trimester maternal circulation and the risk of subsequent development of PE and/or IUGR. These results are generally interpreted to reflect decreased production of the proteases by the placenta, leading to reduced proteolysis of IGFBPs and lower free levels of insulin-like growth factor (IGF), resulting in diminished feto-placental development. However, the association between low circulating levels of placental proteins early in pregnancy and the subsequent development of IUGR and/or PE could be due to low exchange in the placenta and not due to reduced production. In contrast, late in pregnancy, the circulating levels of these proteins and their expression in the placenta are often elevated in PE, which may reflect upregulation to compensate for abnormal placental development, that is an adaptive mechanism to increase IGFBP proteolysis, increase local IGF levels and promote feto-placental growth. Further research into the biological mechanisms underlying these associations will aid the identification of high-risk pregnancies and the development of therapeutic targets for diseases for which there are presently no preventative measures.

Altered placental expression of PAPPA2 does not affect birth weight in mice

BACKGROUND

Pregnancy-associated plasma protein A2 (PAPPA2) is an insulin-like growth factor binding protein (IGFBP) protease expressed in the placenta and upregulated in pregnancies complicated by pre-eclampsia. The mechanism linking PAPPA2 expression and pre-eclampsia and the consequences of altered PAPPA2 expression remain unknown. We previously identified PAPPA2 as a candidate gene for a quantitative trait locus (QTL) affecting growth in mice and in the present study examined whether this QTL affects placental PAPPA2 expression and, in turn, placental or embryonic growth.

METHODS

Using a line of mice that are genetically homogenous apart from a 1 megabase QTL region containing the PAPPA2 gene, we bred mice homozygous for alternate QTL genotypes and collected and weighed placentae and embryos at E12.5. We used quantitative RT-PCR to measure the mRNA levels of PAPPA2, as well as mRNA levels of IGFBP-5 (PAPPA2's substrate), and PAPPA (a closely related IGFBP protease) to examine potential feedback and compensation effects. Western blotting was used to quantify PAPPA2 protein. Birth weight was measured in pregnancies allowed to proceed to parturition.

RESULTS

PAPPA2 mRNA and protein expression levels in the placenta differed by a factor of 2.5 between genotypes, but we did not find a significant difference between genotypes in embryonic PAPPA2 mRNA levels. Placental IGFBP-5 and PAPPA mRNA expression levels were not altered in response to PAPPA2 levels, and we could not detect IGFBP-5 protein in the placenta by Western blotting. The observed difference in placental PAPPA2 expression had no significant effect on placental or embryonic mass at mid-gestation, birth weight or litter size.

CONCLUSIONS

Despite a significant difference between genotypes in placental PAPPA2 expression similar in magnitude to the difference between pre-eclamptic and normal placentae previously reported, we observed no difference in embryonic, placental or birth weight. Our results suggest that elevated PAPPA2 levels are a consequence, rather than a cause, of pregnancy complications.

First-trimester assessment of placenta function and the prediction of preeclampsia and intrauterine growth restriction

Preeclampsia and intrauterine growth restriction (IUGR) are major contributors to perinatal mortality and morbidity worldwide. Both are characterized by impaired trophoblastic invasion of the maternal spiral arteries and their conversion from narrow muscular vessels to wide non-muscular channels. Despite improvement in the understanding of the pathophysiology of these conditions, ability to accurately identify pregnant woman who will develop them is limited. This greatly impairs the development and testing of preventive interventions. While different measures of placental dysfunction have been associated with increased risk for adverse pregnancy outcomes, the ability of any single one to accurately predict these outcomes is poor. Developing predictive tests is further challenged by difficulty in the timing of the measurements, as both the structural and biochemical characteristics of the placenta change with increasing gestational age. The ideal screening test would accurately predict the development of adverse pregnancy outcomes early enough to provide a window for preventive interventions. Improvement in ultrasound technology provides potentially useful novel tools for evaluating placental structure, but measurements need to be standardized in order to be useful. Maternal serum analyte screening is a noninvasive test of placental biochemical function, but present serum marker alone is not sufficiently accurate to suggest its routine use in clinical practice. The use of first trimester biochemical markers in combination with uterine artery Doppler screening is promising as a potential screening tool. Prospective longitudinal studies using standardized methodology are necessary to further evaluate the choice of parameters and strategies of combination to achieve the best predictive models.

Free leptin index and PAPP-A: a first trimester maternal serum screening test for pre-eclampsia

BACKGROUND

Prophylaxis with low-dose aspirin may reduce the risk of pre-eclampsia (PE) if introduced in first trimester. The performance of first trimester maternal serum screening for PE using free leptin index (fLI) and PAPP-A, where fLI = leptin/leptin soluble receptor was studied.

METHODS

First trimester serum samples from 126 PE pregnancies and 289 control pregnancies were studied. fLI and PAPP-A were converted into gestational age and maternal weight independent log MoM values of PAPP-A and fLI. The screening performance of markers was studied by receiver-operator-characteristics curves. The performance of population screening was estimated by Monte Carlo simulation.

RESULTS

fLI was significantly (p < 0.001) elevated [mean log MoM 0.2165 (SD: 0.2604)] compared to controls [mean log MoM -0.0368 (SD: 0.3132)] and PAPP-A was significantly (p < 0.001) reduced [mean log MoM -0.0133 (SD: 0.2661)] compared to controls [mean log MoM 0.0474 (SD: 0.2521)] in PE pregnancies. There was no correlation between fLI and PAPP-A in control or PE pregnancies. Combined fLI and PAPP-A screening for PE had estimated population detection rates of 22% and 35% for false positives rates of 6% and 12%, respectively.

CONCLUSION

Combining PAPP-A and fLI improves screening performance for PE compared to single marker screening.

Maternal serum ADAM12 in Chinese women undergoing screening for aneuploidy in the first trimester

OBJECTIVE

To evaluate the potential of maternal serum using a disintegrin and metalloprotease 12 (ADAM12) as a marker for Trisomy 21 in Chinese pregnant women.

METHODS

Serum samples were collected and stored from women having a viable singleton pregnancy undergoing first trimester screening for Trisomy 21 between 2006 and 2007. Serum concentration of ADAM12 was measured using an automated time-solved immuno-fluorometric assay from 608 stored serum samples (601 Euploidy and 7 Trisomy 21). Regression analysis was used to determine the expected median in Euploidy pregnancies after adjusting for pregnancy characteristics. The level of ADAM12 MoM was compared between Trisomy 21 and Euploidy pregnancies. Expected median levels in Chinese were compared to that published for Caucasians and Afro-Caribbeans.

RESULTS

In Euploidy pregnancies, the concentration of ADAM12 increased with CRL and decreased with maternal weight. The expected median level of ADAM12 in Chinese was significantly lower than Caucasian and Afro-Caribbeans (F=14.2, p<0.0001). There was a significant correlation between log10ADAM12 MoM both log10 pregnancy-associated plasma protein A MoMs (r=0.46; p<0.001) and log10free βhCG MoMs (r=0.08; p=0.048). The median ADAM12 MoM in Trisomy 21 pregnancies was not significantly different from that in Euploidy pregnancies (z=0.18; p=0.88).

CONCLUSION

ADAM12 concentrations in Chinese are lower than those of Caucasians and Afro-Carribeans; that ADAM12 MoM levels in Euploidy and Trisomy 21 pregnancies were not statistically different.

First trimester maternal serum ADAM12s levels in twin pregnancies

BACKGROUND

A disintegrin and metalloprotease 12s (ADAM12s) is a potential first trimester serum marker for fetal trisomy and adverse pregnancy outcome in singletons. In this study, ADAM12s levels in first trimester serum of uncomplicated and complicated twins were evaluated.

METHODS

ADAM12s was studied in maternal serum of 215 twin pregnancies, collected between 2004 and 2008. ADAM12s was measured 'blind to outcome' using AutoDelfia (PerkinElmer, Turku, Finland). As a reference, data from 2423 singletons were used.

RESULTS

The median ADAM12s level was increased in euploid twins [1.61 multiples of the median (MoM); n = 209] compared with singletons. The median ADAM12s MoM was significantly lower in monochorionic (1.36 MoM; n = 41) compared with dichorionic twins (1.67 MoM; n = 168) (Mann-Whitney U test, p = 0.005). Trisomy 21 was identified in two pregnancies. Median ADAM12s MoM in twins complicated by hypertensive disorders (1.77 MoM, n = 35) or small for gestational age fetus (1.54 MoM; n = 24) was not significantly different from uncomplicated twins (1.64 MoM; n = 134).

CONCLUSION

Median ADAM12s MoM in euploid twins was increased compared with singletons. Monochorionic had significantly lower median ADAM12s MoM than dichorionic twins. Median ADAM12s MoMs were not significantly different in twins complicated by hypertensive disorders or small for gestational age fetus compared with uncomplicated twins.

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.