Alterations in placental growth factor levels before and after the onset of preeclampsia are more pronounced in women with early onset severe preeclampsia

Predictive value of the sFlt‑1/PlGF ratio in women with suspected preeclampsia: An update (Review)

Preeclampsia (PE) is a major complication of pregnancy with an incidence rate of 2‑8% and is a leading cause of maternal mortality and morbidity. The various consequences of severe preeclampsia for the fetus, neonate and child include intrauterine growth retardation (IUGR), fetal hypoxia, oligohydramnios, intrauterine fetal demise, increased perinatal mortality and morbidity, neurodevelopmental disorders and even irreversible brain damage (cerebral palsy). A number of studies have demonstrated that differences in maternal serum concentrations of angiogenic factors between preeclampsia and normotensive pregnancies can be used as biomarkers, either alone or in combination with other markers, to predict the development of PE. The presence in the maternal circulation of two proteins of placental origin, placental growth factor (PlGF) and soluble fms‑like tyrosine kinase 1 (sFlt‑1), has been shown to be of clinical value, as the sFlt‑1/PlGF ratio appears to be the optimal predictive tool for the development of PE. The measurement of their concentration in maternal serum in screening models, serves as predictive marker for the development of PE or IUGR later in gestation. However, further research is required to improve its clinical applicability and provide guidelines for its use worldwide to achieve more consistent clinical management of women with PE.

Circulating levels of angiogenic factors and their association with preeclampsia among pregnant women at Mulago National Referral Hospital in Uganda

Preeclampsia (PE) is a major cause of maternal and new-born morbidity and mortality. Angiogenic factors contribute a major role in the vascular dysfunction associated with PE. We investigated the circulating levels of vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and soluble Feline McDonough Sarcoma (fms)-like tyrosine kinase-1 (sFlt1), their association with PE and diagnostic performance of disease among pregnant women in Uganda. Using a case-control study design, 106 women with PE and 106 with normal pregnancy were enrolled. Demographic and clinical characteristics, and anticoagulated blood samples were collected from participants. Plasma VEGF, PlGF and sFlt1 levels were measured using Luminex and enzyme linked immunosorbent assays (ELISA). Conditional logistic regression was used to explore association of angiogenic factors with PE and receiver operating characteristic analysis was performed to investigate PE diagnostic performance. Levels of VEGF and PIGF were significantly lower in cases compared to controls (VEGF: median = 0.71 pg/ml (IQR = 0.38-1.11) Vs 1.20 pg/ml (0.64-1.91), p-value<0.001 and PlGF: 2.20 pg/ml (1.08-5.86) Vs 84.62 pg/ml (34.00-154.45), p-value<0.001). Plasma levels of sFlt1 were significantly higher in cases than controls (median = 141.13 (71.76-227.10) x103 pg/ml Vs 19.86 (14.20-29.37) x103 pg/ml). Increasing sFlt1 levels were associated with increased likelihood of PE (aOR = 4.73; 95% CI, 1.18-19.01; p-value = 0.0287). The sFlt1/PlGF ratio and sFlt1 had a better performance for diagnosis of PE, with AUC = 0.95 (95% CI, 0.93-0.98) followed by PlGF with AUC = 0.94 (95% CI, 0.91-0.97). Therefore, sFlt1, sFlt1/PlGF ratio and PlGF are potential candidates for incorporation into algorithms for PE diagnosis in the Ugandan population.

Association of maternal angiotensin II type 1 and type 2 receptor combination genotypes with susceptibility to early-onset preeclampsia

Allelic variations affecting the activity of the maternal renin-angiotensin system may play a role in the development of hypertensive disorders of pregnancy like preeclampsia, its more severe early-onset form, and intrauterine growth restriction. We examined the association of common allelic variants of angiotensin II type 1 and type 2 receptor genes (AT1R and AT2R) sorted in five AT1R/AT2R receptor combination genotype groups with susceptibility to early-onset preeclampsia (EOP). The occurrence of AT1R (A1166C) and A2TR (C3123A) alleles in wild type (AA, CC), heterozygous (A/C, C/A), and homozygous (C/C, A/A) states was recorded in 84 women with a history of EOP and 84 age-matched controls sorted in five AT1R/AT2R receptor combination genotype (wild type: AA/CC, one mutant: AA/CA, AC/CC, two mutant: AC/CA, AA/AA, CC/CC, three mutants: AC/AA, CC/CA and four mutant: CC/AA) groups, by polymerase chain reaction-RFLP analysis. Three mutant receptor combination genotype carriers were more common in women with a history of EOP than in controls (26.18% vs. 4.76%, p = 0.003, OR = 8.25). Receptor combination genotyping may be of clinical value in: (a) maternal prediction of susceptibility to EOP, (b) disease subtyping for directed studies with receptor signaling antagonists, (c) the broader study of hypertension.

Gene polymorphism associated with TGF-β1 and susceptibility to preeclampsia: A meta-analysis and trial sequential analysis

AIM

Mounts of researches focused on the link between transforming growth factor-beta 1 (TGF-β1) polymorphisms and preeclampsia (PE) which is a hypertensive multisystemic disorder affecting pregnancy. However, the results were inconsistent. Thus, a meta-analysis was performed to obtain more conclusive results.

METHODS

Eligible studies were searched in PubMed, Web of Science, EMBASE, and Scopus. Odds ratios (ORs) with 95% confidence intervals (CIs) were utilized to evaluate the relationship between six TGF-β1 polymorphisms (rs1800468, rs1800469, rs1800470, rs1800471, rs4803455, and rs4803457) and PE susceptibility in five genetic models. The subgroup stratified analysis and trial sequential analysis were performed.

RESULTS

Fourteen studies were included in this meta-analysis with 1941 PE patients and 2488 healthy women. There was no statistically significant association between these six TGF-β1 polymorphisms and PE within five genetic models in the overall population (all p > 0.05). Subgroup stratified analysis revealed there was statistically significant association between TGF-β1 rs1800469 polymorphism and PE within the allele, recessive, and homozygous model in Asian (OR = 1.17, 95% CI = 1.02-1.35; OR = 1.35, 95% CI = 1.06-1.72; OR = 1.48, 95% CI = 1.07-2.05, respectively; all p < 0.05). Trial sequential analysis indicated sufficient proof of such association in the Asian population.

CONCLUSIONS

TGF-β1 rs1800469 is a possible risk factor for PE in Asian populations.

Altered level of salivary placental growth factor is associated with preeclampsia

A pilot, case-control study was conducted to compare the concentrations of placental growth factor (PlGF) and placental alkaline phosphatase (PLAP) in saliva of preeclampsia (PE) patients with normotensive controls in the second and third trimesters. Measured by ELISA assays, levels of salivary PlGF were significantly lower in PE patients (n = 13) compared to controls (n = 15) (two-way ANOVA, p = 0.0208) independent of gestational age at time of collection (p = 0.49). Salivary PLAP differences between PE and controls were not statistically significant. Placenta-specific proteins are detectable in maternal saliva and may serve as noninvasive biomarkers to monitor placenta health and disease during pregnancy.

Association of maternal Toll-like receptor-4 alleles with susceptibility to early-onset preeclampsia in central Greece

INTRODUCTION

Altered maternal inflammatory responses may play a role in the development of hypertensive disorders of pregnancy like preeclampsia, its more severe early-onset form and intrauterine growth restriction. We evaluated the relation of common allelic variants of Toll-like receptor 4 (TLR4), known to impair the inflammatory response, with the susceptibility to early-onset preeclampsia in Central Greece.

METHODS

We compared the occurrence of TLR4 (Asp299Gly and Thr399Ile) alleles in heterozygous (A/G, C/T) and homozygous (G/G, T/T) states in 84 women with a history of early-onset preeclampsia and 94 age matched controls with a history of only uneventful pregnancies, by direct sequencing.

RESULTS

Heterozygous TLR4 allelic variants were more common in women with a history of early-onset preeclampsia than in controls (GA for Asp299Gly: 14.3% vs 6.4% (AA), p = 0.053 & CT for Thr399Ile: 16.7% vs. 6.4% (CC), p = 0.019) and a stronger association was obtained when homozygous allelic carriers were also included (GA/GG for Asp299Gly: 16.7% vs. 6.4% (AA), p = 0.03 & TC/TT for Thr399Ile: 19.0% vs. 6.4% (CC), p = 0.01).

DISCUSSION

We recorded association between common TLR4 gene variants and early-onset preeclampsia. Our findings support the involvement of maternal innate immune system in severe hypertensive disorders of pregnancy and point to the potential value of maternal TLR4 polymorphisms as predictors-risk factors of susceptibility to early-onset preeclampsia in Central Greece.

Clinical usefulness of serum levels of soluble fms-like tyrosine kinase 1/placental growth factor ratio to rule out preeclampsia in women with new-onset lupus nephritis during pregnancy

Measurement of the soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio may be clinically useful to discriminate systemic lupus erythematosus (SLE) from preeclampsia. Here, we present a pregnant woman with new-onset SLE with hypertension, with the measurement of the sFlt-1/PlGF ratio during pregnancy. A 31-year-old Japanese nulliparous woman, who had been diagnosed with idiopathic thrombocytopenic purpura at 10 years, had a systolic blood pressure of 120 mmHg and was negative for proteinuria at 12⁺¹ weeks. Since her blood pressure increased to 159/86 mmHg with 3+ proteinuria at 25⁺⁴ weeks, preeclampsia was suspected. Deterioration of the kidney function (creatinine: 0.58 mg/dL at 24⁺⁶ weeks to 0.83 mg/dL at 33⁺⁶ weeks) necessitated cesarean section at 33⁺⁶ weeks. After delivery, she still showed increased creatinine and proteinuria. Therefore, she was transferred to a nephrology specialist in a tertiary center and was finally diagnosed with SLE with lupus nephritis class IV-G(A) (diffuse lupus nephritis). The serum levels of sFlt-1 and the sFlt-1/PlGF ratio, which are usually elevated in preeclampsia, were within normal reference ranges at 27⁺⁶, 28⁺¹, and 28⁺⁶ weeks of gestation, although the serum levels of PlGF were slightly lower than the normal reference range. In conclusion, measurement of the sFlt-1/PlGF ratio may be clinically useful to discriminate lupus nephritis from preeclampsia.

Addition of N-terminal pro-B natriuretic peptide to soluble fms-like tyrosine kinase-1/placental growth factor ratio > 38 improves prediction of pre-eclampsia requiring delivery within 1 week: a longitudinal cohort study

OBJECTIVE

Short-term prediction of pre-eclampsia (PE) using the soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio is characterized by frequent false-positive results. As such, no treatment can be recommended to test-positive patients and multiple measurements are often required. The aim of this study was to evaluate the effectiveness of N-terminal pro-B natriuretic peptide (NT-proBNP), uric acid and the sFlt-1/PlGF ratio for prediction of delivery with PE within 1 week in singleton pregnancies with suspected PE and sFlt-1/PlGF ratio > 38.

METHODS

This was a longitudinal prospective cohort study of singleton pregnancies presenting at 24 + 0 to 36 + 6 weeks of gestation with clinically suspected PE and sFlt-1/PlGF ratio > 38, enrolled between January 2015 and June 2017. Multiple samples per patient were allowed but were restricted to one sample per gestational week. From 495 enrolled patients, 270 blood samples from 134 patients were ultimately analyzed. By using generalized estimating equations (GEE), the best-fit model was selected for prediction of delivery with PE within 1 week. The predictive value of this model was then assessed using area under the paired-ROC curve (AUC) analysis.

RESULTS

The best-fit model included the sFlt-1/PlGF ratio, NT-proBNP and the gestational week at the time of the measurement. This combined model was compared with the GEE model based on the sFlt-1/PlGF ratio and the gestational week at the time of the measurement (reduced model). The AUC for the combined model was 0.845 (95% CI, 0.787-0.896), which was significantly greater (P = 0.011) than that of the reduced model (0.786 (95% CI, 0.722-0.844)).

CONCLUSION

The addition of NT-proBNP assessment improves the short-term prediction of delivery as a result of PE compared with sFlt-1/PlGF ratio alone, when the sFlt-1/PlGF ratio is > 38. This finding should be considered in future research on the assessment of short-term risk of delivery as a result of PE. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

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.

Placental growth factor (alone or in combination with soluble fms-like tyrosine kinase 1) as an aid to the assessment of women with suspected pre-eclampsia: systematic review and economic analysis

BACKGROUND

Pre-eclampsia (PE) prediction based on blood pressure, presence of protein in the urine, symptoms and laboratory test abnormalities can result in false-positive diagnoses. This may lead to unnecessary antenatal admissions and preterm delivery. Blood tests that measure placental growth factor (PlGF) or the ratio of soluble fms-like tyrosine kinase 1 (sFlt-1) to PlGF could aid prediction of PE if either were added to routine clinical assessment or used as a replacement for proteinuria testing.

OBJECTIVES

To evaluate the diagnostic accuracy and cost-effectiveness of PlGF-based tests for patients referred to secondary care with suspected PE in weeks 20-37 of pregnancy.

DESIGN

Systematic reviews and an economic analysis.

DATA SOURCES

Bibliographic databases including MEDLINE, EMBASE, Web of Science and The Cochrane Library and Database of Abstracts of Reviews of Effects were searched up to July 2015 for English-language references. Conferences, websites, systematic reviews and confidential company submissions were also accessed.

REVIEW METHODS

Systematic reviews of test accuracy and economic studies were conducted to inform an economic analysis. Test accuracy studies were required to include women with suspected PE and report quantitatively the accuracy of PlGF-based tests; their risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) criteria. The economic studies review had broad eligibility criteria to capture any types of economic analysis; critical appraisal employed standard checklists consistent with National Institute for Health and Care Excellence criteria. Study selection, critical appraisal and data extraction in both reviews were performed by two reviewers.

ECONOMIC ANALYSIS

An independent economic analysis was conducted based on a decision tree model, using the best evidence available. The model evaluates costs (2014, GBP) from a NHS and Personal Social Services perspective. Given the short analysis time horizon, no discounting was undertaken.

RESULTS

Four studies were included in the systematic review of test accuracy: two on Alere's Triage^® PlGF test (Alere, Inc., San Diego, CA, USA) for predicting PE requiring delivery within a specified time and two on Roche Diagnostics' Elecsys^® sFlt-1 to PlGF ratio test (Roche Diagnostics GmbH, Mannheim, Germany) for predicting PE within a specified time. Three studies were included in the systematic review of economic studies, and two confidential company economic analyses were assessed separately. Study heterogeneity precluded meta-analyses of test accuracy or cost-analysis outcomes, so narrative syntheses were conducted to inform the independent economic model. The model predicts that, when supplementing routine clinical assessment for rule-out and rule-in of PE, the two tests would be cost-saving in weeks 20-35 of gestation, and marginally cost-saving in weeks 35-37, but with minuscule impact on quality of life. Length of neonatal intensive care unit stay was the most influential parameter in sensitivity analyses. All other sensitivity analyses had negligible effects on results.

LIMITATIONS

No head-to-head comparisons of the tests were identified. No studies investigated accuracy of PlGF-based tests when used as a replacement for proteinuria testing. Test accuracy studies were found to be at high risk of clinical review bias.

CONCLUSIONS

The Triage and Elecsys tests would save money if added to routine clinical assessment for PE. The magnitude of savings is uncertain, but the tests remain cost-saving under worst-case assumptions. Further research is required to clarify how the test results would be interpreted and applied in clinical practice.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015017670.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

N-terminal pro B-type natriuretic peptide and angiogenic biomarkers in the prognosis of adverse outcomes in women with suspected preeclampsia

BACKGROUND

This study compares the performance of the soluble fms-like tyrosine kinase 1 to placental growth factor (sFlt-1/PlGF) ratio and the cardiac biomarker N-terminal pro-B type natriuretic peptide (NT-proBNP) in the prediction of adverse outcomes in women with suspicion of PE.

METHODS

A retrospective cohort study was conducted on women admitted at triage with signs and/or symptoms of PE (n=340). Serum levels of sFlt-1, PlGF and NT-proBNP were determined by an electrochemiluminescence immunoassay (Roche Diagnostics). The main outcomes were early- or late-onset PE and development of adverse outcome, defined as delivery within the first week since clinical presentation or fetal/early neonatal death.

RESULTS

NT-proBNP concentrations (ng/L) were significantly increased in PE versus non-PE women, both at <34 (169 versus 34) and ≥34weeks of gestation (101 versus 49) (p<0.001). A cut-point of 70 showed sensitivities/specificities of 78/74% for early-, and 70/62% for late-onset PE; slightly lower than those offered by the sFlt-1/PlGF ratio or uric acid. The respective cut-points of 178 and 219 for sFlt-1/PlGF ratio and NT-proBNP, demonstrated similar performance in the prediction of adverse outcome, with sensitivity/specificity of 95/84% and 94/76%, respectively.

CONCLUSION

NT-proBNP and sFlt-1/PlGF ratio can be used to predict the development of an adverse outcome.

Prediction and prevention of hypertensive disorders of pregnancy

The most common classifications of hypertensive disorders of pregnancy consist of chronic hypertension, gestational hypertension, preeclampsia (PE) and superimposed PE. A common final pathophysiology of PE is endothelial dysfunction. The most successful translational research model for explaining the cause-effect relationship in the genesis of PE is the angiogenic/angiostatic balance theory, involving soluble fms-like tyrosine kinase 1 (sFlt-1), placental growth factor (PlGF) and soluble endoglin (sEng). In a systematic review of articles on the prediction of early-onset PE using angiogenesis-related factors, we revealed that the prediction of early-onset PE in the first trimester is clinically possible, but the prediction of early-onset PE in the early third trimester might be ideal. In addition, an onset threshold or a serial approach appeared to be clinically useful for predicting the imminent onset of PE, with onset at <4 weeks after blood sampling in the second and early third trimesters, because the positive likelihood ratio was >10 and the positive predictive value was >20%. The National Institute for Health and Care Excellence guidelines state that the Triage PlGF testing and Elecsys immunoassay for the sFlt-1/PlGF ratio could help to exclude PE in women with suspected PE at 20-34 weeks of gestation. Until now, we have not found any effective therapies to prevent PE. However, low-dose aspirin treatment starting at ⩽16 weeks of gestation might be associated with a marked reduction in PE. In addition, early statin treatment might prevent the occurrence of PE. Currently, a clinical trial using pravastatin for the prevention of PE is ongoing.

Polymorphisms in Inflammatory Mediator Genes and Risk of Preeclampsia in Taiyuan, China

Excessive maternal inflammatory response is involved in the pathogenesis of preeclampsia. Few epidemiologic studies have investigated the associations between genetic variations in the inflammatory mediator genes and preeclampsia risk, and these studies have reached inconsistent results. We examined 31 single-nucleotide polymorphisms in IL-1A, IL-1B, IL-1R1, IL-2RA, IL-5RA, IL-6, IL-6R, TNFSF11, TNFRSF11A, IL-28RA, IRAK4, and KIT genes and the risk of preeclampsia and its clinical subtypes in a nested case-control study including 203 preeclampsia cases and 233 controls. We found that IL-1R1, IL-5RA, IL-6R, and TNFSF11 were associated with the risk of preeclampsia. Although the significant associations observed for preeclampsia overall were mainly seen for late-onset preeclampsia and severe preeclampsia, IL-6R (rs2229238) and TNFSF11 (rs9525643) polymorphisms were associated with the risk of early-onset preeclampsia. TNFSF11 (rs2200287 and rs2148072) polymorphisms were associated with risk of mild preeclampsia. Our study provided the first evidence that genetic variations in inflammatory mediator genes IL-1R1, IL-6R, TNFSF11, and IL-5RA were associated with preeclampsia risk, and the risk varied by preeclampsia subtypes.

Polymorphisms in complement genes and risk of preeclampsia in Taiyuan, China

BACKGROUND AND OBJECTIVES

Altered immune response may be a part of the pathogenesis of preeclampsia. The few epidemiologic studies that have investigated the associations between genetic variations in the complement system genes and preeclampsia risk have reached inconsistent results. The aim of this study is to determine if polymorphisms in the complement system genes could influence the risk of preeclampsia.

METHODS

We examined 51 SNPs in the C3, C5, C6, MASP1, MBL2 and CD55 genes and the risk of preeclampsia and its clinical subtypes in a nested case-control study of 203 preeclampsia cases and 233 controls.

RESULTS

Both C6 and MASP1 were associated with the risk of preeclampsia. C6 (rs7444800, rs4957381) and MASP1 (rs1108450, rs3774282, rs698106) polymorphisms were associated with the risk of early-onset preeclampsia and severe preeclampsia, while MASP1 (rs1357134, rs698090) polymorphisms were associated with the risk of late-onset preeclampsia and severe preeclampsia.

CONCLUSIONS

Our study provided novel evidence that genetic variations in complement genes C6 and MASP1were associated with preeclampsia risk, and that the risk varied by preeclampsia subtypes.

Placental endoplasmic reticulum stress negatively regulates transcription of placental growth factor via ATF4 and ATF6β: implications for the pathophysiology of human pregnancy complications

Low maternal circulating concentrations of placental growth factor (PlGF) are one of the hallmarks of human pregnancy complications, including fetal growth restriction (FGR) and early-onset pre-eclampsia (PE). Currently, PlGF is used clinically with other biomarkers to screen for high-risk cases, although the mechanisms underlying its regulation are largely unknown. Placental endoplasmic reticulum (ER) stress has recently been found to be elevated in cases of FGR, and to an even greater extent in early-onset PE complicated with FGR. ER stress activates the unfolded protein response (UPR); attenuation of protein translation and a reduction in cell growth and proliferation play crucial roles in the pathophysiology of these complications of pregnancy. In this study, we further identified that ER stress regulates release of PlGF. We first observed that down-regulation of PlGF protein was associated with nuclear localization of ATF4, ATF6α and ATF6β in the syncytiotrophoblast of placentae from PE patients. Transcript analysis showed a decrease of PlGF mRNA, and an increase from genes encoding those UPR transcription factors in placentae from cases of early-onset PE, but not of late-onset (>34 weeks) PE, compared to term controls. Further investigations indicated a strong correlation between ATF4 and PlGF mRNA levels only (r = - 0.73, p < 0.05). These results could be recapitulated in trophoblast-like cells exposed to chemical inducers of ER stress or hypoxia-reoxygenation. The stability of PlGF transcripts was unchanged. The use of small interfering RNA specific for transcription factors in the UPR pathways revealed that ATF4 and ATF6β, but not ATF6α, modulate PlGF transcription. To conclude, ATF4 and ATF6β act synergistically in the negative regulation of PlGF mRNA expression, resulting in reduced PlGF secretion by the trophoblast in response to stress. Therefore, these results further support the targeting of placental ER stress as a potential new therapeutic intervention for these pregnancy complications.

Placental growth factor and vascular endothelial growth factor serum levels in Tunisian Arab women with suspected preeclampsia

The angiogenic factors vascular endothelial growth factor (VEGF) and placental growth factor (PIGF) play a central role in the process of angiogenesis. We evaluated the association of free PIGF and free VEGF levels and the risk of preeclampsia (PE) among Tunisian Arab women, and established the range of VEGF and PIGF in normal healthy pregnancies, between 24 and 42weeks of gestation. This retrospective case-control study included 345 women with PE, and 289 women with uncomplicated pregnancies. PIGF and VEGF plasma levels were quantitated by commercially-available ELISA. Compared to control women, plasma PIGF concentrations were lower in women with PE at all gestation age intervals (P<0.0001), compared to VEGF levels which were significantly lower in women with PE but only during early gestation age intervals ([29-32[ and [32-35[). High odds for developing PE, and correspondingly higher associations, were associated with low PIGF values (less than the 5(th) percentile), at all gestation age intervals. The only exception was recorded for the [29-32 [interval, which was not statistically significant. PIGF testing, recorded at 29-37weeks of gestation, had a higher specificity (93-100%) than sensitivity, and the positive predictive values ranged from 90% to 100% for 24-37weeks of gestation. This indicates that it mainly detects non-PE healthy women as well, and thus may be useful as a screening test, though currently unreliable for diagnostic purposes. Reduced PIGF levels during different gestation age intervals, and reduced VEGF levels during early gestation age intervals are also associated with subsequent development of PE in our population; the gestational age interval adjusted-5(th) percentiles of PIGF provide reference ranges for this marker in normal pregnancy.

A Prospective Study of Placental Growth Factor Assay as a Novel Biomarker in Predicting Early-Onset Preeclampsia in High-Risk Patients

INTRODUCTION

Preeclampsia is a leading cause of maternal and perinatal mortality and morbidity, but signs and symptoms are non-specific and may vary. The root cause is imbalance of circulating angiogenic factors of placental (syncytiotrophoblast) origin, with consequent low levels of placental growth factor (PlGF) which may aid in diagnosis and prediction of disease.

AIMS AND OBJECTIVES

To study the incidence of women at risk of developing early-onset preeclampsia by plasma placental growth factor biomarker assay in high-risk patients, to assess the maternal outcome in patients with PlGF values below cutoff for presenting gestational age, to calculate sensitivity, specificity, positive predictive value and negative predictive value of PlGF assay in predicting preeclampsia and to conclude whether PlGF biomarker assay can be an effective screening test in high-risk patients for prediction of early-onset preeclampsia.

MATERIALS AND METHODS

The study was carried out in the Department of Obstetrics and Gynecology at a tertiary care center. It is a prospective study, and study period extended from April 2012 to October 2013. One hundred pregnant women with 20- to 34-week gestational age with possible high risk of developing preeclampsia attending the antenatal clinics and high-risk OPDs were screened in the present study after explaining the nature of the study. PLGF concentration was quantitated using plasma and processed in Triage kit device (fluorescence immunoassay device). PLGF concentration was categorized against a specific range for specific gestation, and values below the range or <12 pg/ml were considered screened positives. The cases were followed up till delivery.

RESULTS

Twenty-two cases were screened positive, of which 20 developed preeclampsia with a strong positive prediction value of more than 90 %.

CONCLUSION

PLGF is a strong predictor and a useful assay for early-onset preeclampsia.

Association between adverse pregnancy outcome and imbalance in angiogenic regulators and oxidative stress biomarkers in gestational hypertension and preeclampsia

Background

Gestational hypertension (GH) and Preeclampsia, (PE) are the most complicated amongst hypertensive disorders of pregnancy. The mechanism that links hypertension in pregnancy to adverse maternal outcomes is not fully understood though some relate this to endothelial dysfunction originating from an imbalanced angiogenic regulators and oxidative stress biomarkers. This study assessed the correlation between angiogenic regulators and oxidative stress biomarker levels with adverse pregnancy outcomes among GH and PE participants.

Methods

A cohort of pregnant women who received antenatal care at the Obstetrics and Gynaecology department of the Komfo Anokye Teaching Hospital (KATH) were followed. During their antenatal visits, 100 developed PE and 70 developed GE, of these, 50 PE and 50 GH gave informed consent. Their blood samples were taken at time of diagnosis and 48 h post-partum. 50 other aged-matched women who did not develop neither GH nor PE were selected as controls. Placental growth factor (PLGF), soluble fms-like tyrosine kinase 1 (sFlt-1) and 8-epi-prostaglandin F2alpha (8-epi-PGF2α) levels were estimated by ELISA and total antioxidant capacity (T-AOC) was measured spectrophotometrically. Graphpad Prism was used for data analysis.

Results

Median levels of sFlt-1, 8-epi-PGF2α and sFlt-1/PLGF were elevated among participants with PE co-existing with intrauterine fetal death (IUFD), placental abruptio, placental previa, HELLP syndrome and intrauterine growth restriction (IUGR) compared to PE without adverse outcomes (p = 0.041, p = 0.005, p = 0.0002). Levels of PLGF, T-AOC and PLGF/sFlt-1 were significantly reduced among participants with PE co-existing with IUFD, placental abruptio, placental previa, HELLP syndrome and IUGR compared to PE without adverse outcomes (p = 0.0013, p = 0.006, p < 0.0001). A significant negative correlation of IUGR (p = 0.0030; p < 0.0001), placental abruptio (p < 0.0001; p < 0.0001), IUFD (p < 0.0001; p < 0.0001), stillbirth (p = 0.0183 and p < 0.000), and postpartum haemorrhage (PPH) (p = 0.0420; p = 0.0044) were associated with both PLGF and T-AOC whilst a significant positive correlation of IUGR, placental abruptio (p < 0.0001; p < 0.0001), IUFD (p < 0.0001; p < 0.0001), stillbirth (p < 0.0001; p < 0.0001), and PPH (p = 0.0043; p = 0.0039) were observed with both sFlt-1 and 8-epi-PGF2α in PE.

Conclusions

Imbalance in the levels of angiogenic regulators and oxidative stress biomarkers correlates with adverse pregnancy outcomes among PE participants. Early identification of these imbalance would alert health care givers in anticipation of adverse pregnancy outcome and thus increased surveillance during pregnancy and parturition and measures to ameliorate the adverse outcome.

Maternal Smoking History Enhances the Expression of Placental Growth Factor in Invasive Trophoblasts at Early Gestation Despite Cessation of Smoking

Maternal smoking during early pregnancy is associated with a reduced risk for preeclampsia even after smoking cessation during pregnancy. Although the pathophysiology of preeclampsia has not been established, placental growth factor (PlGF) is believed to be a key factor. The aim of this study was to assess the effect of maternal smoking on the PlGF expression in invasive trophoblasts at early gestation. We collected villous tissues from women requesting surgical termination due to non-medical reasons at 7-8 weeks of gestation. The maternal smoking status was evaluated by measuring the serum cotinine level and patients were divided into two groups: active smokers and non-smokers. After separating invasive trophoblasts from villous tissues cultured initially under 2% O2 for 24 hours, the separated invasive trophoblasts were cultured under 2% or 8% O2 for 48 hours. The expression levels of the PlGF gene in villous tissue specimens and in invasive trophoblasts cultured after the conditions were quantified using qRT-PCR. The levels of PlGF protein in the medium were quantified using an ELISA. The gene expression level of PlGF in the villi in the active-smokers was significantly higher than that of the non-smokers. In comparison of the invasive trophoblasts under normoxia and oxygenated conditions, the ratio of PlGF gene expression and protein expression under oxygenation (2% O2+8% O2 / 2% O2+2% O2) in the active-smokers were both significantly higher than in the non-smokers. Maternal smoking history appears to stimulate PlGF expression in invasive trophoblasts under oxygenated conditions. This may be one of several causes leading to the protective effect of maternal smoking on preeclampsia.

Role of maternal plasma levels of placental growth factor for the prediction of maternal complications in preeclampsia according to the gestational age at onset

OBJECTIVE

This study aimed to describe the distribution of placental growth factor (PlGF) plasma levels in pregnancies complicated by preeclampsia (PE) according to the gestational age at clinical onset and to assess PlGF's predictive role for maternal complications.

METHODS

A total of 84 women whose pregnancies were complicated by PE before 37 weeks' gestation were enrolled. According to gestational age at onset, three groups were defined: group I, <28 weeks; group II, 28 to 31(+6)  weeks; and group III, 32 to 36(+6)  weeks. PlGF plasma levels were measured at diagnosis, and their association with maternal complications was investigated. Plasma PlGF levels below 12 pg/mL were designated as very low.

RESULTS

PlGF levels were very low in seven (87.5%) of eight women diagnosed before 28 weeks' gestation, 29 (78.4%) of 37 patients diagnosed between 28 and 32 weeks' gestation, and 16 (41%) of 39 cases diagnosed after 32 weeks' gestation. The sensitivity of very low PlGF values for predicting maternal complications was 76.9%, but the false positive rate was 65.5%. Positive and negative predictive values were 34.5% and 76.9%, respectively.

CONCLUSION

The predictive role of a low PlGF level in predicting maternal complications in very early PE is limited because of both its low specificity and low positive predictive value.

Differential activation of placental unfolded protein response pathways implies heterogeneity in causation of early- and late-onset pre-eclampsia

Based on gestational age at diagnosis and/or delivery, pre-eclampsia (PE) is commonly divided into early-onset (<34 weeks) and late-onset (≥34 weeks) forms. Recently, the distinction between ‘placental’ and ‘maternal’ causation has been proposed, with ‘placental’ cases being more frequently associated with early-onset and intrauterine growth restriction. To test whether molecular placental pathology varies according to clinical presentation, we investigated stress-signalling pathways, including unfolded protein response (UPR) pathways, MAPK stress pathways, heat-shock proteins and AMPKα in placentae delivered by caesarean section for clinical indications at different gestational ages. Controls included second-trimester, pre-term and normal-term placentae. BeWo cells were used to investigate how these pathways react to different severities of hypoxia–reoxygenation (H/R) and pro-inflammatory cytokines. Activation of placental UPR and stress-response pathways, including P-IRE1α, ATF6, XBP-1, GRP78 and GRP94, P-p38/p38 and HSP70, was higher in early-onset PE than in both late-onset PE and normotensive controls (NTCs), with a clear inflection around 34 weeks. Placentae from ≥ 34 weeks PE and NTC were indistinguishable. Levels of UPR signalling were similar between second-trimester and term controls, but were significantly higher in pre-term ‘controls’ delivered vaginally for chorioamnionitis and other conditions. Severe H/R (1/20% O₂) induced equivalent activation of UPR pathways, including P-eIF2α, ATF6, P-IRE1α, GRP78 and GRP94, in BeWo cells. By contrast, the pro-inflammatory cytokines TNFα and IL-1β induced only mild activation of P-eIF2α and GRP78. AKT, a central regulator of cell proliferation, was reduced in the < 34 weeks PE placentae and severe H/R-treated cells, but not in other conditions. These findings provide the first molecular evidence that placental stress may contribute to the pathophysiology of early-onset pre-eclampsia, whereas that is unlikely to be the case in the late-onset form of the syndrome. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Increased antiangiogenetic factors in severe proteinuria without hypertension in pregnancy: is kidney biopsy necessary?

Acute onset of severe proteinuria during pregnancy obliges physicians to clinically discriminate between gestational proteinuria (GP) and new onset of nephritis. A multiparous woman developed severe proteinuria (5.8 g/day) without hypertension at 32 weeks of gestation. We measured the maternal level of soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng), which were extremely high (41.3 and 54.8 ng/ml, respectively), leading us to consider this condition as GP rather than acute onset of nephritis. Thus, we did not perform a kidney biopsy and did not administer a steroid agent. Non-reassuring fetal status required emergency Cesarean section at 33 weeks. Proteinuria decreased to 0.36 g/day at 12 weeks after delivery, and finally disappeared 26 weeks postpartum. Measurement of sFlt-1 and sEng in a pregnant woman with severe proteinuria without hypertension may assist in differential diagnosis of GP from acute onset of nephritis, and thus help to decide whether to perform kidney biopsy during pregnancy.

Maternal plasma concentrations of angiogenic/antiangiogenic factors in the third trimester of pregnancy to identify the patient at risk for stillbirth at or near term and severe late preeclampsia

OBJECTIVE

To determine whether maternal plasma concentrations of placental growth factor (PlGF), soluble endoglin (sEng), and soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) at 30-34 weeks of gestation can identify patients at risk for stillbirth, late preeclampsia, and delivery of small-for-gestational-age (SGA) neonates.

STUDY DESIGN

A prospective cohort study included 1269 singleton pregnant women from whom blood samples were obtained at 30-34 weeks of gestation and who delivered at >34 weeks of gestation. Plasma concentrations of PlGF, sEng, and sVEGFR-1 were determined by enzyme-linked immunosorbent assay.

RESULTS

The prevalence of late (>34 weeks of gestation) preeclampsia, severe late preeclampsia, stillbirth, and SGA was 3.2% (n = 40), 1.8% (n = 23), 0.4% (n = 5), and 8.5% (n = 108), respectively. A plasma concentration of PlGF/sEng <0.3 MoM was associated with severe late preeclampsia (adjusted odds ratio, 16); the addition of PlGF/sEng to clinical risk factors increased the area under the receiver-operating characteristic curve from 0.76 to 0.88 (P = .03). The ratio of PlGF/sEng or PlGF/sVEGFR-1 in the third trimester outperformed those obtained in the first or second trimester and uterine artery Doppler velocimetry at 20-25 weeks of gestation for the prediction of severe late preeclampsia (comparison of areas under the receiver-operating characteristic curve; each P ≤ .02). Both PlGF/sEng and PlGF/sVEGFR-1 ratios achieved a sensitivity of 74% with a fixed false-positive rate of 15% for the identification of severe late preeclampsia. A plasma concentration of PlGF/sVEGFR-1 <0.12 MoM at 30-34 weeks of gestation had a sensitivity of 80%, a specificity of 94%, and a likelihood ratio of a positive test of 14 for the identification of subsequent stillbirth. Similar findings (sensitivity 80%; specificity 93%) were observed in a separate case-control study.

CONCLUSION

Risk assessment for stillbirth and severe late preeclampsia in the third trimester is possible with the determination of maternal plasma concentrations of angiogenic and antiangiogenic factors at 30-34 weeks of gestation.

Plasma level of hydroxysteroid (17-β) dehydrogenase 1 in the second trimester is an independent risk factor for predicting preeclampsia after adjusting for the effects of mean blood pressure, bilateral notching and plasma level of soluble fms-like tyrosine kinase 1/placental growth factor ratio

Mean blood pressure (MBP), bilateral notching (BN) in the uterine artery and increased circulating levels of soluble fms-like tyrosine kinase-1/placental growth factor (sFlt-1/PlGF) ratio are predictors of preeclampsia (PE). Recently, we disclosed that reducing the plasma level of hydroxysteroid (17-β) dehydrogenase 1 (HSD17B1), which is a steroidogenetic enzyme catalyzing the conversion of estrone to 17β-estradiol, is a potential prognostic factor for PE. Our aim was to evaluate whether HSD17B1 is an independent risk factor for predicting PE after adjusting for the effects of MBP, BN and the plasma level of the sFlt-1/PlGF ratio in the second trimester. One hundred and twenty-eight consecutive normal pregnant women without gestational hypertension (GH) or PE and 30 women with PE were selected from 1724 pregnant women. Multivariate logistic regression with a forward stepwise procedure was used to construct a prediction model. A past history of GH/PE, a family history of hypertension, pre-pregnancy body mass index, MBP, BN, plasma levels of sFlt-1/PlGF ratio and plasma levels of HSD17B1 were significantly associated with the occurrence of PE; however, only MBP (OR (95% confidence interval), 1.08 (1.03-1.14)), BN (7.5 (1.9-30)), sFlt-1/PlGF (21 (2.7-163)) and HSD17B1 (0.43 (0.22-0.85)) were independent risk factors for PE. The area under the receiver-operating-characteristic curve for the combination model was 0.89, yielding a sensitivity of 0.84, a specificity of 0.88 and a positive likelihood ratio of 7.2 (4.0-13). In conclusion, HSD17B1 is an independent risk factor for PE, and the combination of several risk factors including HSD17B1 in the second trimester may improve the prediction of PE.

Low placental growth factor across pregnancy identifies a subset of women with preterm preeclampsia: type 1 versus type 2 preeclampsia?

Preeclampsia is a heterogeneous syndrome affecting 3% to 5% of all pregnancies. An imbalance of the antiangiogenic and proangiogenic factors, soluble receptor fms-like tyrosine kinase 1 and placental growth factor (PGF), is thought to contribute to the pathophysiology of preeclampsia. Maternal plasma PGF and soluble receptor fms-like tyrosine kinase 1 were quantified by specific immunoassays in cross-sectional samples from 130 preeclamptic subjects and 342 normotensive controls at delivery and longitudinally in samples from 50 women who developed preeclampsia and 250 normotensive controls. Among women who developed preeclampsia, 46% (n=23) evidenced a pattern of consistently low maternal PGF across pregnancy below the lower 95% CI of controls from 15 weeks' gestation to term. In contrast, the remaining 54% (n=27) of women who developed preeclampsia had maternal PGF concentrations similar to or above (n=7) those of normotensive controls. Subjects with low PGF across pregnancy who developed preeclampsia evidenced significantly higher blood pressure in early pregnancy (P<0.05) and, after diagnosis, earlier gestational age at delivery (P<0.05) and more preterm birth (P<0.05) compared with preeclamptic patients with high PGF. A significant subset of women who develop preeclampsia show evidence of consistently low PGF across pregnancy. Low PGF with preeclampsia was associated with preterm delivery compared with preeclamptic patients with high PGF. Identifying women with consistently low plasma PGF during pregnancy may provide a greater understanding of preeclampsia pathophysiology and may provide more focused research and clinical activities.

Late-onset preeclampsia is associated with an imbalance of angiogenic and anti-angiogenic factors in patients with and without placental lesions consistent with maternal underperfusion

OBJECTIVE

An imbalance between maternal angiogenic/anti-angiogenic factors concentrations has been observed in preeclampsia (PE) and other obstetrical syndromes. However, the frequency of pathologic findings in the placenta and the changes in maternal plasma angiogenic/anti-angiogenic factor concentrations differ between late- and early-onset PE. The aim of this study was to determine if the maternal plasma concentrations of placental growth factor (PlGF), soluble endoglin (sEng), and soluble vascular endothelial growth factor receptor-1 and 2 (sVEGFR-1 and sVEGFR-2) are different in late-onset PE with and without placental pathologic findings consistent with maternal underperfusion.

STUDY DESIGN

A cross-sectional study was conducted including 64 uncomplicated women and 66 women with late-onset PE (>34 weeks) who had blood samples and placenta available for pathologic examination. Patients with late-onset PE were divided into those with and without placental histologic findings consistent with maternal underperfusion as proposed by the Society for Pediatric Pathology. Maternal plasma concentrations of PlGF, sEng, sVEGFR-1 and sVEGRF-2 were determined by ELISA. Non-parametric statistics were used for analysis.

RESULTS

1) the prevalence of placental histological findings consistent with maternal underperfusion among women with late-onset PE was higher than that of those with an uncomplicated pregnancy (47% (31/66) vs. 7.8% (5/64), respectively; p < 0.01); 2) patients with late-onset PE and histological findings consistent with maternal underperfusion had a significantly lower median plasma concentration of PlGF, plasma PlGF/sVEGFR-1 ratio and plasma PlGF/sEng ratio than those with late-onset PE without placental underperfusion lesions (each p < 0.05); 3) the most common pathological findings in the placenta of patient with PE were lesions consistent with villous changes (77%, 24/31); and 4) isolated vascular lesions in the placenta were found only in 2 cases (6.5%), and the rest had a combination of villous and vascular lesions.

CONCLUSIONS

Nearly half of the patients with late-onset PE have placental lesions consistent with maternal underperfusion. These lesions are associated with an imbalance in the maternal concentration of angiogenic/anti-angiogenic factors. We propose that there is a link between maternal underperfusion and an anti-angiogenic state characterized by the changes in the concentrations of angiogenic and anti-angiogenic factors in women with late onset PE.

The promise of angiogenic markers for the early diagnosis and prediction of preeclampsia

BACKGROUND

An imbalance in circulating factors that regulate blood vessel formation and health, referred to as angiogenic factors, plays a central role in the pathogenesis of preeclampsia.

CONTENT

Several studies have demonstrated a strong association between altered circulating angiogenic factors and preeclampsia. These factors include circulating antiangiogenic proteins such as soluble fms-like tyrosine kinase 1 and soluble endoglin and proangiogenic protein such as placental growth factor. Abnormalities in these circulating angiogenic factors are not only present during clinical disease, but also antedate clinical signs and symptoms by several weeks. These alterations are particularly prominent in patients who present with preeclamptic signs and symptoms prematurely and/or in patients with severe preeclampsia. The availability of automated platforms for the rapid measurement of circulating angiogenic proteins in blood samples has now allowed researchers and clinicians to evaluate the utility of these assays in the diagnosis of the disease, in the stratification of patients in clinical trials, or in the monitoring of therapies. In this review we highlight the various studies that have been performed, with a focus on large validation studies.

SUMMARY

Measurement of circulating angiogenic proteins for the diagnosis and prediction of preeclampsia is still at an early stage but is rapidly evolving. Standardization across the various automated platforms and prospective studies that demonstrate clinical utility are needed.

Angiogenic factors as diagnostic tests for preeclampsia: a performance comparison between two commercial immunoassays

OBJECTIVE

Placental growth factor and soluble Fms-like tyrosine kinase-1 may be potential diagnostic markers of preeclampsia. We compared performances of 2 immunoassays, the Triage placental growth factor assay and the Elecsys soluble Fms-like tyrosine kinase-1/placental growth factor ratio in diagnosing preeclampsia.

STUDY DESIGN

A single site, case-control study of 44 patients with preeclampsia and 84 matched normal pregnant controls. Samples were collected at the time of diagnosis. Assays were performed according to product inserts.

RESULTS

Both assays had optimal performance in diagnosing early-onset preeclampsia with area under the receiver operating characteristic curves of 0.99 (Triage: 100% sensitivity, 96% specificity; Elecsys: 64% sensitivity, 100% specificity for early-onset preeclampsia). Reassignment of the Elecsys cutoff for a positive test based on receiver operating characteristic curves increased sensitivity to 92%.

CONCLUSION

Using product insert cutoffs, Triage appears to have greater sensitivity at only a small reduction in specificity compared with Elecsys in the diagnosis of early-onset preeclampsia. A different cutoff may improve Elecsys sensitivity.

Maternal plasma concentrations of angiogenic/anti-angiogenic factors are of prognostic value in patients presenting to the obstetrical triage area with the suspicion of preeclampsia

OBJECTIVE

To determine whether maternal plasma concentrations of placental growth factor (PlGF), soluble endoglin (sEng), soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and -2 could identify patients at risk for developing preeclampsia (PE) requiring preterm delivery.

STUDY DESIGN

Patients presenting with the diagnosis "rule out PE" to the obstetrical triage area of our hospital at <37 weeks of gestation (n = 87) were included in this study. Delivery outcomes were used to classify patients into four groups: I) patients without PE or those with gestational hypertension (GHTN) or chronic hypertension (CHTN) who subsequently developed PE at term (n = 19); II): mild PE who delivered at term (n = 15); III): mild disease (mild PE, GHTN, CHTN) who subsequently developed severe PE requiring preterm delivery (n = 26); and IV): diagnosis of severe PE (n = 27). Plasma concentrations of PlGF, sEng, sVEGFR-1 and -2 were determined at the time of presentation by ELISA. Reference ranges for analytes were constructed by quantile regression in our laboratory (n = 180; 1046 samples). Comparisons among groups were performed using multiples of the median (MoM) and parametric statistics after log transformation. Receiver operating characteristic curves, logistic regression and survival analysis were employed for analysis.

RESULTS

The mean MoM plasma concentration of PlGF/sVEGFR-1, PlGF/sEng, PlGF, sVEGFR-1 and -2, and sEng in Group III was significantly different from Group II (all p < 0.05). A plasma concentration of PlGF/sVEGFR-1 ≤ 0.05 MoM or PlGF/sEng ≤0.07 MoM had the highest likelihood ratio of a positive test (8.3, 95% CI 2.8-25 and 8.6, 95% CI 2.9-25, respectively), while that of PlGF ≤0.396 MoM had the lowest likelihood ratio of a negative test (0.08, 95% CI 0.03-0.25). The association between low plasma concentrations of PlGF/sVEGFR-1 (≤0.05 MoM) as well as that of PlGF/sEng (≤0.07 MoM) and the development of severe PE remained significant after adjusting for gestational age at presentation, average systolic and diastolic blood pressure, and a history of chronic hypertension [adjusted odds ratio (OR) = 27 (95% CI 6.4-109) and adjusted OR 30 (95% CI 6.9-126), respectively]. Among patients who presented <34 weeks gestation (n = 59), a plasma concentration of PlGF/sVEGFR-1 < 0.033 MoM identified patients who delivered within 2 weeks because of PE with a sensitivity of 93% (25/27) and a specificity of 78% (25/32). This cut-off was associated with a shorter interval-to-delivery due to PE [hazard ratio = 6 (95% CI 2.5-14.6)].

CONCLUSIONS

Plasma concentrations of angiogenic/anti-angiogenic factors are of prognostic value in the obstetrical triage area. These observations support the value of these biomarkers in the clinical setting for the identification of the patient at risk for disease progression requiring preterm delivery.

Threshold of soluble fms-like tyrosine kinase 1/placental growth factor ratio for the imminent onset of preeclampsia

It has not been clarified whether thresholds of soluble fms-like tyrosine kinase 1 (sFlt-1), placental growth factor (PlGF), soluble endoglin, and the sFlt-1/PlGF ratio for the imminent onset of preeclampsia (PE) exist. We hypothesized that onset thresholds for the imminent onset of PE could be determined by the distributions of these 4 markers just after the onset of PE. Study subjects were 51 PE after the onset of PE; 36 of PE, 20 of gestational hypertension, 142 of a small-for-gestational-age infant, and 400 of normal pregnant controls at 19 to 25 and 27 to 31 weeks of gestation in a prospective cohort study. The current data supported our hypothesis that onset thresholds of sFlt-1 and the sFlt-1/PlGF ratio exist. The onset thresholds of the sFlt-1/PlGF at 26 to 31 weeks of gestation were useful for detecting imminent PE with the onset at <36 weeks of gestation, showing sensitivity of 0.36 and a positive likelihood ratio and 95th percent CIs of 38 (11-132); when positive, PE occurred at 2.2±0.6 weeks (range: 1.4-3.0 weeks) after the measurement of the sFlt-1/PlGF ratio. The combination of sFlt-1 at 26 to 31 weeks of gestation, past history of gestational hypertension or PE, prepregnancy body mass index, and mean blood pressure at 16 to 23 weeks of gestation was useful for detecting PE with onset of <36 weeks of gestation, showing sensitivity of 0.82, and a positive likelihood ratio (95% CI) of 42 (20-88). In conclusion, the onset threshold of sFlt-1/PlGF existed and might be useful for detecting the imminent onset of PE.

The unique pathophysiology of early-onset severe preeclampsia: role of decidual T regulatory cells

Immunological mechanisms play a pivotal role in the pathophysiology of preeclampsia. T regulatory cells (Treg cells, FoxP3(+)) suppress the cytotoxic T cell (CD8(+)) and natural killer (NK) cell response, thereby promoting immunological tolerance to the fetus. In peripheral blood, Treg cells are elevated during pregnancy, decrease throughout gestation, and are decreased in preeclampsia. To determine their role at the implantation site, we characterized the proportion of decidual Treg and CD8+ cells, and compared these with placental histology, villous sFlt expression, and chorionic trophoblast apoptotic index in normal and preeclamptic pregnancies. Decidua from first (n=5) and second (n=4) trimester terminations and chorioamniotic membranes, containing decidua, from term deliveries (n=14), early-onset (≤ 34 weeks) (n=12), and late-onset (>34 weeks) (n=14) severe preeclampsia were evaluated. Immunohistochemistry for CD3, CD8, and FoxP3 was performed: CD8(+) and FoxP3(+) cells were calculated as a proportion of CD3(+) cells. Placental tissue was evaluated for villous hypermaturity and sFlt staining. Chorioamniotic membranes were evaluated, via TUNEL assay, for chorionic trophoblast apoptosis. Decidual Treg cells were seen to peak in second trimester and decrease with advancing gestational age and were lower in early-onset (0.46%) compared with late-onset severe preeclampsia (3.34%) and term pregnancies (5.21%). The proportion of CD8(+) cells was higher in cases of severe preeclampsia. Early-onset severe preeclamptic cases had the highest sFlt score, placental insufficiency score, and apoptotic index. Our data suggest that early-onset severe preeclampsia has a unique pathophysiology involving defective immunoregulatory pathways, potentially causing vascular and trophoblast damage at the implantation site.

Sildenafil citrate decreases sFlt-1 and sEng in pregnant l-NAME treated Sprague-Dawley rats

OBJECTIVES

We have previously shown that sildenafil citrate improves various fetal outcomes in pregnant, L-NAME treated, Sprague-Dawley rats. We therefore aimed to identify which component/s of this diverse pathophysiologic cascade is/are improved by this drug.

STUDY DESIGN

This study is a sub-analysis of plasma samples obtained in a previous study in which 24 pregnant Sprague-Dawley dams were divided into three groups (n=8) i.e. the control group (CON), the experimental control group (PRE) where the pre-eclampsia-like symptoms were induced using l-NAME, and the experimental group (SCT) where the pre-eclampsia-like symptoms were once again induced using L-NAME but these animals were treated with sildenafil citrate. On gestation day 20 blood samples were collected in heparin-coated tubes and plasma samples were then analysed for specific variables using commercially available kits for rats.

RESULTS

There was a significant increase in the plasma levels of soluble fms-like tyrosine kinase1 (sFlt-1) in the PRE group (1228.80±116.29 pg/ml) when compared to the CON (774.91±26.81 pg/ml) and SCT (698.98±20.78 pg/ml) groups, respectively (p<0.001). The plasma levels of soluble endoglin (sEng) were significantly decreased in the SCT group (149.47±3.72 ng/ml) when compared to the CON (178.52±5.33 ng/ml) and PRE (183.44±8.294 ng/ml) groups, respectively (p<0.01). Plasma nitric oxide and l-arginine levels showed a decreasing trend in the PRE groups when compared to the control (CON) and treated (SCT) groups, respectively.

CONCLUSION

Sildenafil citrate reduces the plasma levels of anti-angiogenic factors, sFlt-1 and sEng, in pre-eclamptic (L-NAME induced) Sprague-Dawley rats and may therefore be responsible for the reduction in blood pressure and proteinuria as well as the improved fetal outcomes noted in an earlier study.

Circulating angiogenic and antiangiogenic factors in women with eclampsia

OBJECTIVE

The objective of the study was to determine whether eclampsia has a different circulating profile of angiogenic (placental growth factor [PlGF]) and antiangiogenic factors (soluble vascular endothelial growth factor receptor-1 [sVEGFR-1] and soluble endoglin [sEng]) from severe preeclampsia.

STUDY DESIGN

This cross-sectional study included pregnant women in the following groups: (1) normal pregnancy (n = 40); (2) severe preeclampsia (n = 40); and (3) eclampsia (n = 20). Maternal serum PlGF, sVEGFR-1, and sEng concentrations were determined using an enzyme-linked immunosorbent assay.

RESULTS

The study results included the following: (1) the median concentration of sVEGFR-1 and sEng was higher and of PlGF was lower in severe preeclampsia or eclampsia than in normal pregnancy (P < .001 for all); and (2) the median concentrations of these 3 analytes did not differ significantly between patients with severe preeclampsia and those with eclampsia.

CONCLUSION

Eclampsia is associated with higher maternal circulating concentrations of sVEGFR-1 and sEng and lower concentrations of PlGF than normal pregnancy but with similar concentrations to severe preeclampsia. These findings suggest that eclampsia shares a common pathogenic pathway as severe preeclampsia.

Gestational hypertension as a subclinical preeclampsia in view of serum levels of angiogenesis-related factors

It is controversial whether gestational hypertension (GH) and preeclampsia (PE) have the same pathophysiology. Our aim was to clarify whether the serum soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio and levels of soluble endoglin (sEng) are different in women with GH and with PE. In women with GH (15 cases), hypertension preceding PE (h-PE, 10 cases) and PE in which hypertension and proteinuria occurred simultaneously (si-PE, 36 cases), blood samples were collected after disease onset. The levels of log(10)(sFlt-1/PlGF) in women with GH were significantly lower than in women with h-PE and si-PE (1.65±0.39 vs. 2.22±0.35 and 2.15±0.46). The levels of log(10)sEng in women with GH were also significantly lower than in women with h-PE and si-PE (1.51±0.43 vs. 1.87±0.21 and 1.85±0.32). The incidence rates of the sFlt-1/PlGF ratio 95th percentile of the reference value were 73, 100 and 92%, respectively, (P=0.080), and those of sEng 95th percentile were 67, 100 and 89%, respectively, (P=0.053). In conclusion, the levels of sFlt-1/PlGF ratio and sEng in women with GH were lower than in those with h-PE and with si-PE; however, the majority of women with GH showed abnormal increases of both sFlt-1/PlGF ratio and sEng, suggesting that GH may be a subclinical PE in view of serum levels of angiogenesis-related factors.

Serum and plasma determination of angiogenic and anti-angiogenic factors yield different results: the need for standardization in clinical practice

OBJECTIVE

The importance of an anti-angiogenic state as a mechanism of disease in preeclampsia is now recognized. Assays for the determination of concentrations of soluble vascular endothelial growth factor receptor (sVEGFR)-1, sVEGFR-2, placental growth factor (PlGF) and soluble endoglin (sEng) have been developed for research and clinical laboratories. A key question is whether these factors should be measured in plasma or serum. The purpose of this study was to determine if there are differences in the concentrations of these analytes between plasma and serum in normal pregnancy and in preeclampsia.

METHODS

Samples of maternal blood were obtained by venipuncture and collected in EDTA (lavender top) and serum collection tubes (red top). A standard laboratory procedure was implemented for the centrifugation, aliquoting and storage of samples. Plasma and serum from 70 women with normal pregnancies and 34 patients with preeclampsia were assayed for sVEGFR-1, sVEGFR-2, PlGF and sEng by ELISA. Nonparametric paired tests were used for analyses.

RESULTS

A significant difference between plasma and serum concentration was observed for sVEGFR-1 and sVEGFR-2 in normal pregnancy, and for sVEGFR-1, sVEGFR-2, PlGF and sEng in women with preeclampsia.

CONCLUSION

The concentrations of sVEGFR-1, sVEGFR-2, PlGF and sEng when measured in maternal plasma and in serum are different. Therefore, the matrix used for the assay (serum versus plasma) needs to be considered when selecting thresholds for predictive studies and interpreting the growing body of literature on this subject.

Angiogenic imbalances: the obstetric perspective

Clinical and experimental evidence indicates that angiogenic imbalances may participate in the mechanisms of disease of several pregnancy complications, some of which may be life threatening. This article reviews current evidence in support of this view and the possibility that the fetus may play a central role in these imbalances; it also reviews recent experimental observations that modulation of angiogenic imbalances during pregnancy may have prophylactic and/or therapeutic value.