Changes in circulating concentrations of soluble fms-like tyrosine kinase-1 and placental growth factor measured by automated electrochemiluminescence immunoassays methods are predictors of preeclampsia

Clinical usefulness of angiogenic factors in women with chronic kidney disease and suspected superimposed preeclampsia

BACKGROUND

Preeclampsia is a condition often superimposed to CKD.

OBJECTIVE

The purpose of this study was to evaluate the clinical characteristics and outcomes of pregnant women with chronic kidney disease (CKD) with suspected superimposed preeclampsia, stratified according to the degree of their angiogenic imbalance, as assessed by the soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio.

METHODS

Using a cross-sectional design, we studied 171 pregnancies in patients with CKD and with suspected superimposed preeclampsia, admitted to a teaching hospital. Patients were divided into three groups based on their degree of angiogenic imbalance, evaluated by the sFlt-1/PlGF ratio: no angiogenic imbalance (sFlt-1/PlGF ratio≤ 38), mild angiogenic imbalance (sFlt-1/PlGF ratio> 38 to < 85), and severe angiogenic imbalance (sFlt-1/PlGF ratio≥ 85). Superimposed preeclampsia and preeclampsia-related adverse outcomes were defined according to The American College of Obstetricians and Gynecology criteria.  Measurements of sFlt-1 and PlGF were performed on single serum samples using the Elecsys sFlt-1 and PlGF assays (Roche Diagnostics). Serum soluble endoglin (sEng) levels were also determined (ELISA R&D Systems, Minneapolis, MN). Glomerular filtration rate (GFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula, whenever possible on pre-prengancy data.

RESULTS

Patients with severe angiogenic imbalance had higher rates of confirmed superimposed preeclampsia and preeclampsia-related adverse maternal and perinatal outcomes (p < 0.001) when compared to patients with no or mild angiogenic imbalance. A significant trend towards higher serum sEng levels was observed as the degree of angiogenic imbalance increased. Interestingly, the rate of progression to superimposed preeclampsia increased progressively as the degree of angiogenic imbalance increased (no 11.8%, mild 60.0%, and severe 100%).

CONCLUSION

In women with CKD and suspected superimposed preeclampsia, severe angiogenic imbalance was associated with confirmed superimposed preeclampsia or progression to superimposed preeclampsia. Patients with no angiogenic imbalance displayed lower rates of progression to superimposed preeclampsia, whereas outcomes were intermediate, supporting a systematic use of sFlt-1/PlGF ratio, and other biomarkers in the clinical management of CKD pregnacies.

Novel Cardiovascular Biomarkers Associated with Increased Cardiovascular Risk in Women With Prior Preeclampsia/HELLP Syndrome: A Narrative Review

Evidence has shown that women with a history of preeclampsia or haemolysis, elevated liver enzymes and low platelets (HELLP) syndrome have an increased risk of cardiovascular disease later in life. Recommendations for screening, prevention and management after such pregnancies are not yet defined. The identification of promising non-traditional cardiovascular biomarkers might be useful to predict which women are at greatest risk. Many studies are inconsistent and an overview of the most promising biomarkers is currently lacking. This narrative review provides an update of the current literature on circulating cardiovascular biomarkers that may be associated with an increased cardiovascular disease risk in women after previous preeclampsia/HELLP syndrome. Fifty-six studies on 53 biomarkers were included. From the summary of evidence, soluble fms-like tyrosine kinase-1, placental growth factor, interleukin (IL)-6, IL-6/IL-10 ratio, high-sensitivity cardiac troponin I, activin A, soluble human leukocyte antigen G, pregnancy-associated plasma protein A and norepinephrine show potential and are interesting candidate biomarkers to further explore. These biomarkers might be potentially eligible for cardiovascular risk stratification after preeclampsia/HELLP syndrome and may contribute to the development of adequate strategies for prevention of hypertension and adverse events in this population.

Evaluation of Angiogenic Factors (PlGF and sFlt-1) in Pre-eclampsia Diagnosis

OBJECTIVE

 Recent observations support the hypothesis that an imbalance between angiogenic factors has a fundamental role in the pathogenesis of pre-eclampsia and is responsible for the clinical manifestations of the disease. The goal of the present study was to evaluate the sensitivity, specificity, and the best accuracy level of Soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF), and sFlt-1/PlGF ratio in maternal serum and protein/creatinine ratio in urine sample to define the best cutoff point of these tests to discriminate between the patients with gestational hypertension and the patients with pre-eclampsia, to evaluate the possibility of using them as diagnostic methods.

METHODS

 A prospective longitudinal study was performed, and blood samples were collected from 95 pregnant patients with hypertension to measure serum concentrations of biomarkers sFlt-1 and PlGF. Urine samples were collected for protein screening. Significance was set as p < 0.05.

RESULTS

 The sFlt-1/PlGF ratio demonstrated a sensitivity of 57.5% and a specificity of 60% using 50.4 as a cutoff point. The test that showed the best accuracy in the diagnosis of pre-eclampsia was protein/creatinine ratio, with a sensitivity of 78.9% and a specificity of 70% using 0.4 as a cutoff point and showing an area under the receiver operating characteristic curve of 0.80 (p < 0.001).

CONCLUSION

 No studied laboratory test proved to be fairly accurate for the diagnosis of pre-eclampsia, except for the protein/creatinine ratio. The evidence is insufficient to recommend biomarkers sFlt-1 and PlGF to be used for the diagnosis of pre-eclampsia.

Circulating angiogenic factors are associated with progression to preeclampsia and the occurrence of adverse outcomes in women with gestational hypertension

OBJECTIVE

Gestational hypertension is characterized by an imbalance in angiogenic factors. The goal of the current study was to evaluate whether circulating concentrations of proangiogenic and antiangiogenic factors are associated with the risk of progression to preeclampsia and development of adverse outcomes in women with gestational hypertension.

METHODS

We studied 496 women with gestational hypertension. Patients were divided into three groups based on their degree of angiogenic imbalance, evaluated by the soluble fms-like tyrosine kinase-1/placental growth factor ratio: no angiogenic imbalance (≤38), mild angiogenic imbalance (>38-<85), and severe angiogenic imbalance (≥85) or stratified into tertiles according to soluble endoglin (sEng) levels.

RESULTS

The concentrations of all angiogenic factors were significantly different in patients with gestational hypertension than in healthy pregnancy. A significant trend towards higher serum sEng levels was observed as the degree of angiogenic imbalance increased. Patients with severe angiogenic imbalance had higher rates of adverse maternal and perinatal outcomes and progression to preeclampsia (P < 0.001) when compared with patients with no or mild angiogenic imbalance. The risk of combined adverse maternal outcomes and specific adverse outcomes (hemolysis, elevated liver enzymes, low platelet count syndrome, preterm delivery, small-for-gestational-age infant, perinatal death, and progression to preeclampsia within 7, 14, 28, and 56 days) was higher in patients with severe angiogenic imbalance or sEng values in the highest tertile (odds ratio ≥5.6 and ≥2.0, respectively), compared with no angiogenic imbalance or the lowest tertile.

CONCLUSION

In women with gestational hypertension at the time of initial evaluation, circulating concentrations of the soluble fms-like tyrosine kinase-1/placental growth factor ratio and sEng appear to be suitable markers to assess the risk of adverse maternal and perinatal outcomes and progression to preeclampsia.

Usefulness of the sFlt-1/PlGF (Soluble fms-Like Tyrosine Kinase-1/Placental Growth Factor) Ratio in Diagnosis or Misdiagnosis in Women With Clinical Diagnosis of Preeclampsia

Preeclampsia is characterized by angiogenic imbalance (AI), sFlt-1 (soluble fms-like tyrosine kinase-1)/PlGF (placental growth factor) is useful for its diagnosis and prediction of adverse outcomes, but the relationship among the degrees of AI as assessed by this ratio with the correct diagnosis, clinical characteristics, and outcomes in women with clinical diagnosis of preeclampsia are unclear. We studied 810 women with clinical diagnosis of preeclampsia. Patients were divided into 3 groups based on their degree of AI, evaluated by the sFlt-1/PlGF ratio: no AI (≤38), mild AI (>38-<85), and severe AI (≥85). Patients with no AI were more likely to have comorbidities and false significant proteinuria compared with patients with mild and severe AI (P<0.001). The rates of preterm delivery, delivery within 14 days, and small-for-gestational-age infant were higher among patients with severe AI than in patients with no and mild AI (P<0.001) and in patients with mild AI that in those with no AI (P≤0.01). The occurrence of any adverse maternal outcome (HELLP syndrome, elevated liver enzymes, thrombocytopenia, placental abruption, acute kidney injury) was only present in patients with severe AI. Interestingly, the frequency of misdiagnosis of preeclampsia was progressively lower as the degrees of AI increased (no AI: 100%, mild AI: 88.2%, and severe AI: 15.6%). We concluded that in women with clinical diagnosis of preeclampsia, severe AI is characterized by high frequency of true preeclampsia and preeclampsia-related adverse outcomes, in contrast, no and mild AI, are characterized by unnecessary early deliveries, often due to misdiagnosis.

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.

Soluble Endoglin As a Marker for Preeclampsia, Its Severity, and the Occurrence of Adverse Outcomes

Preeclampsia is characterized by an imbalance in angiogenic factors, including sEng (soluble endoglin). However, the relationship of sEng with the severity of preeclampsia, clinical, and laboratory parameters, and the occurrence of adverse outcomes are not fully elucidated. We studied 1002 women with preeclampsia. Serum concentrations of sEng were measured by ELISA. Serum sEng levels were significantly different (P<0.001) in patients with preeclampsia than in healthy pregnancy. In addition, these factors were markedly different in patients with hemolysis, elevated liver enzymes, low platelet count syndrome and eclampsia than in patients with preeclampsia with or without severe features (P<0.001) and in patients with preeclampsia with severe features than in those without severe features (P<0.001). sEng correlated positively with blood pressure, proteinuria, and levels of creatinine, uric acid, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase; and inversely with gestational age, infant's birth weight, and platelets counts (P<0.001 for all). The risk of combined and specific adverse outcomes (pulmonary edema, acute renal failure, placental abruption, hepatic hematoma or rupture, maternal death, cerebral hemorrhage, thrombocytopenia, elevated liver enzymes, preterm delivery, small for gestational age infant, and need for endotracheal intubation, positive inotropic drug support, and hemodialysis) was higher in patients with sEng values in the highest quartile (odds ratio ≥3.1) compared with the lowest quartile. Patients in the highest quartile of sEng were more likely to deliver early compared with those in the lowest quartile (HR, 2.33; 95% CI, 1.91-2.84). We concluded that circulating concentrations of sEng seem to be a suitable marker to assess the severity of preeclampsia and are associated with increased risk of adverse outcomes.

Association between fertility treatments and early placentation markers

INTRODUCTION

Pregnancies resulting from fertility treatments are at higher risk of placenta-mediated complications. Hence, we aimed to estimate the association between fertility treatment and levels of first-trimester markers of placentation.

METHODS

We conducted a cohort study in an academic center from 03/2011 to 12/2014. Adult nulliparous women with singleton pregnancies were recruited between 11 ^+ 0 and 13 ^+ 6 weeks of gestation. Data on maternal characteristics, medical history, and pregnancies conceived through fertility treatments (whether ovulation agents, insemination or assisted reproductive technologies) were collected. Maternal serum concentrations of PlGF, sFlt-1, PAPP-A, AFP, and free β-hCG were obtained, and notches and UtA-PI were measured using Doppler ultrasound. Mean Multiple of the Medians (MoM) and frequencies were computed to estimate the mean differences (MD) or risk ratios (RR) comparing fertility treatment to spontaneous pregnancies.

RESULTS

427 (9%) pregnancies out of 4815 were conceived through fertility treatments, using ovulation agents (n = 233, 5%), insemination (n = 174, 4%) and/or assisted reproductive technologies (n = 85, 2%). The latter were associated with significantly lower log₁₀PAPP-A MoM (adjusted MD: -0.02, 95%CI: -0.04 to -0.01), lower log₁₀PlGF MoM (adjusted MD: -0.04, 95%CI: -0.06 to -0.01) and higher log₁₀free β-hCG MoM (adjusted MD: 0.05, 95%CI: 0.01 to 0.09) compared to spontaneous pregnancies. Ovulation agents and insemination were associated with the presence of notches (adjusted RR: 1.24, 95%CI: 1.14 to 1.35; and 1.27, 95%CI: 1.15 to 1.42, respectively) and higher log₁₀UtA-PI MoM (adjusted MD: 0.16, 95%CI: 0.08 to 0.24; and 0.17, 95%CI: 0.07 to 0.27, respectively) than spontaneous pregnancies.

CONCLUSION

Fertility treatments are associated with significant variations in markers of placentation.

Pre-eclampsia: pathogenesis, novel diagnostics and therapies

Pre-eclampsia is a complication of pregnancy that is associated with substantial maternal and fetal morbidity and mortality. The disease presents with new-onset hypertension and often proteinuria in the mother, which can progress to multi-organ dysfunction, including hepatic, renal and cerebral disease, if the fetus and placenta are not delivered. Maternal endothelial dysfunction due to circulating factors of fetal origin from the placenta is a hallmark of pre-eclampsia. Risk factors for the disease include maternal comorbidities, such as chronic kidney disease, hypertension and obesity; a family history of pre-eclampsia, nulliparity or multiple pregnancies; and previous pre-eclampsia or intrauterine fetal growth restriction. In the past decade, the discovery and characterization of novel antiangiogenic pathways have been particularly impactful both in increasing understanding of the disease pathophysiology and in directing predictive and therapeutic efforts. In this Review, we discuss the pathogenic role of antiangiogenic proteins released by the placenta in the development of pre-eclampsia and review novel therapeutic strategies directed at restoring the angiogenic imbalance observed during pre-eclampsia. We also highlight other notable advances in the field, including the identification of long-term maternal and fetal risks conferred by pre-eclampsia.

Predictive value of the sFlt-1 and PlGF in women at risk for preeclampsia in the south of Vietnam

BACKGROUND

It has been suggested that soluble fms-like tyrosine kinase receptor-1 (sFlt-1) and placental growth factor (PlGF) play potential roles in preeclampsia diagnosis. Nevertheless, studies on the use of sFlt-1, PlGF, and sFlt-1/PlGF ratio in predicting preeclampsia have found contradictory results. Thus, more studies in different populations are needed.

OBJECTIVES

This study aims to (i) examine the associations between sFlt-1, PlGF, or sFlt-1/PlGF ratio at gestational ages of 24-28 weeks and subsequent preeclampsia, and (ii) estimate predictive values of these markers in southern Vietnamese women.

METHODS

We used a nested case-control design from a cohort of 490 pregnant women who were at risk of preeclampsia. The total sample size for statistical analysis consisted of 30 cases and 67controls. Levels of sFlt-1 and PlGF were quantified by using a fully automated electrochemiluminescence immunoassay platform (Elecsys®/Cobas®).

RESULTS

The median of sFlt-1 concentration was not statistically different between case and control groups. The median PlGF concentration was lower (349.7 pg/ml versus 534.6 pg/ml, P < .001) and the median sFlt-1/PlGF ratio was higher in the preeclampsia group (4.3 versus 1.9, P < .001). After adjusting for maternal age, gestational age, nullipara, and body mass index, the odds of preeclampsia in women with an sFlt-1/PlGF ratio in the fourth quartile were 10 times greater than in women with an sFlt-1/PlGF ratio in the other quartiles (95% confidence interval, 3.2-31.4; P < .001).

CONCLUSIONS

This study contributes to the literature that sFlt-1/PlGF ratio measured at gestational weeks 24-28 in southern Vietnamese women can separate preeclamptic from normotensive cases.

Lower circulating angiotensin II levels are related to the severity of preeclampsia and its risk as disclosed by a specific bioassay

Preeclampsia is characterized by an increased sensitivity to angiotensin II (Ang II). We herein assessed whether serum Ang II levels measured by a new developed bioassay are associated with preeclampsia, its severity, and the risk for developing this disease.Using a cross-sectional design, we studied 90 pregnant women (30 healthy pregnant and 60 with preeclampsia [30 with- and 30 without severe features]). We also used a nested case-control study with 30 women who eventually developed preeclampsia and 31 normotensive controls. Serum samples were collected at diagnosis of preeclampsia or at 4-week intervals (from weeks 12th to 36th). Ang II was measured using a bioassay.At diagnosis of preeclampsia, serum Ang II concentrations were significantly lower in preeclampsia without and with severe features (P = .001 and P < .001, respectively) than in healthy pregnancy. In addition, Ang II was different in preeclampsia with severe features than in those without severe features (P = .048). Women who subsequently developed preeclampsia had lower Ang II levels than women with normal pregnancies, and these changes became significant at 24 weeks onward. The risk to developing preeclampsia was higher among women with Ang II concentration values in the lowest quartile of the control distribution from 12 weeks onward (odds ratio ranging from 3.8 [95% CI 1.3-11.1] to 6.5 [95% CI 1.6-26.9]).We concluded that concentrations of Ang II are markedly diminished at diagnosis of preeclampsia and are closely associated with the severity of disease. Changes in circulating levels of Ang II precede the clinical presentation of preeclampsia.

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.

Vascular Dysfunction in Mother and Offspring During Preeclampsia: Contributions from Latin-American Countries

Pregnancy is a physiologically stressful condition that generates a series of functional adaptations by the cardiovascular system. The impact of pregnancy on this system persists from conception beyond birth. Recent evidence suggests that vascular changes associated with pregnancy complications, such as preeclampsia, affect the function of the maternal and offspring vascular systems, after delivery and into adult life. Since the vascular system contributes to systemic homeostasis, defective development or function of blood vessels predisposes both mother and infant to future risk for chronic disease. These alterations in later life range from fertility problems to alterations in the central nervous system or immune system, among others. It is important to note that rates of morbi-mortality due to pregnancy complications including preeclampsia, as well as cardiovascular diseases, have a higher incidence in Latin-American countries than in more developed countries. Nonetheless, there is a lack both in the amount and impact of research conducted in Latin America. An impact, although smaller, can be seen when research in vascular disorders related to problems during pregnancy is analyzed. Therefore, in this review, information about preeclampsia and endothelial dysfunction generated from research groups based in Latin-American countries will be highlighted. We relate the need, as present in many other countries in the world, for increased effective regional and international collaboration to generate new data specific to our region on this topic.

The influence of prenatal exercise and pre-eclampsia on maternal vascular function

During healthy pregnancy, the cardiovascular system undergoes diverse adaptations to support adequate transfer of oxygen and nutrients from mother to fetus. In order to accommodate the large expansion of blood volume and associated cardiac output, the structure, mechanics, and function of the arteries are altered. Specifically, in healthy pregnancy there is a remodeling of arteries (increased angiogenesis and vasodilation), a generalized reduction in arterial stiffness (increased compliance), and an enhanced endothelial function. The development of pregnancy complications, specifically pre-eclampsia, is associated with poor placentation (decreased angiogenesis), increased arterial stiffness, and vascular dysfunction (reduced endothelial function). Many of the positive adaptations that occur in healthy pregnancy are enhanced in response to chronic exercise. Specifically, placental angiogenesis and endothelial function have been shown to improve to a greater extent in women who are active during their pregnancy compared with those who are not. Prenatal exercise may be important in helping to reduce the risk of vascular dysfunction in pregnancy. However, our knowledge of the vascular adaptations resulting from maternal exercise is limited. This review highlights maternal vascular adaptations occurring during healthy pregnancy, and contrasts the vascular maladaptation associated with pre-eclampsia. Finally, we discuss the role of prenatal exercise on vascular function in the potential prevention of vascular complications associated with pre-eclampsia.

Influences of placental growth factor on mouse retinal vascular development

BACKGROUND

Placental growth factor (PGF) is important for wound-healing and vascular collaterogenesis. PGF deficiency is associated with preeclampsia, a hypertensive disease of human pregnancy. Offspring born to preeclamptic mothers display cognitive impairments and brain vascular and neurostructural deviations. Low PGF production during development may contribute to alterations in offspring cerebrovascular beds. Retina is a readily accessible part of the central nervous system with a well-described pattern of vascular development in mice. Impacts of PGF deficiency were addressed during mouse retinal vascularization.

RESULTS

Retinal vessels were compared between Pgf^-/- and congenic C57BL/6 (B6) mice. PGF deficiency altered neonatal retinal vascularization patterns. Some anatomic alterations persisted into adulthood, particularly in males. Greater arterial wall collagen IV expression was found in adult Pgf^-/- females. Pregnancy (studied in adult females at gestational days 11.5 or 18.5) induced subtle changes upon the mother's retinal vasculature but these pregnancy-induced changes did not differ between genotypes. Significant sex-related differences occurred between adult male and female B6 although sexually dimorphic retinal vascular differences were absent in B6 neonates.

CONCLUSIONS

Overall, PGF has a role in retinal vascular angiogenesis and vessel organization during development but does not affect retinal vessel adaptations in adult females during pregnancy. Developmental Dynamics 246:700-712, 2017. © 2017 Wiley Periodicals, Inc.

Association between angiogenic factors and signs of arterial aging in women with pre-eclampsia

OBJECTIVE

Pre-eclampsia (PE) is associated with an increased risk of cardiovascular disease later in life. In cases with PE there is a substantial increase in levels of the antiangiogenic factor soluble fms-like tyrosine kinase-1 (sFlt-1) and decreased levels of the proangiogenic factor placental growth factor (PlGF). Elevated levels of sFlt-1 are also found in individuals with cardiovascular disease. The aims of this study were to assess levels of sFlt-1, PlGF and the sFlt-1/PlGF ratio and their correlation with signs of arterial aging by measuring the common carotid artery (CCA) intima and media thicknesses and their ratio (I/M ratio) in women with and without PE.

METHODS

Serum sFlt-1 and PlGF levels were measured using commercially available enzyme-linked immunosorbent assay kits, and CCA intima and media thicknesses were estimated using high-frequency (22-MHz) ultrasonography in 55 women at PE diagnosis and in 64 women with normal pregnancy at a similar gestational age, with reassessment at 1 year postpartum.

RESULTS

During pregnancy, higher levels of sFlt-1, lower levels of PlGF, a thicker intima, a thinner media and a higher I/M ratio of the CCA were found in women with PE vs controls (all P < 0.0001). Further, sFlt-1 and the sFlt-1/PlGF ratio were positively correlated with intima thickness and I/M ratio (all P < 0.0001). At 1 year postpartum, levels of sFlt-1 and the sFlt-1/PlGF ratio had decreased in both groups; however, their levels in the PE group were still higher than in the controls (P = 0.001 and < 0.0001, respectively). Levels of sFlt-1 and the sFlt-1/PlGF ratio remained positively correlated with intima thickness and I/M ratio at 1 year postpartum.

CONCLUSIONS

Higher sFlt-1 levels and sFlt-1/PlGF ratio in women with PE were positively associated with signs of arterial aging during pregnancy. At 1 year postpartum, sFlt-1 levels and the sFlt-1/PlGF ratio were still higher in the PE group and were associated with the degree of arterial aging. © 2016 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

MiR133b is involved in endogenous hydrogen sulfide suppression of sFlt-1 production in human placenta

Increased production of soluble fms-like tyrosine kinase-1 (sFlt-1) from placenta is one of the major contributors to the development of preeclampsia. Our previous study has shown that hydrogen sulfide (H₂S) inhibits sFlt-1 release in placenta. In the present study, we sought to investigate whether endogenous H₂S affects sFlt-1 production and elucidate which H₂S-producing enzyme is responsible for its effect in placenta. It was found that, besides cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), 3-mercaptopyruvatesulfurtransferase (3-MST) was identified in human placenta and mainly localized in syncytiotrophoblasts. There was no significant difference in expression level of 3-MST among preeclamptic and normal placentas. Treatment of cultured syncytiotrophoblasts with NaHS and l-cysteine suppressed sFlt-1 mRNA expression and caused a decrease in sFlt-1 protein content in culture media of the cells. Transfection of syncytiotrophoblasts with CBS siRNA and CSE siRNA reversed the above effects of l-cysteine. Furthermore, NaHS and l-cysteine treatment decreased the half-life of sFlt-1 mRNA and increased the expression of miR-133b targeting sFlt-1. MiR-133b expression was downregulated in preeclamptic placentas and correlated with the level of CBS and CSE. These results indicate that H₂S is an important regulatory factor in sFlt-1 production in placenta. Reduced H₂S generation in placenta contributes to development of preeclampsia by enhancing sFlt-1 production.

Circulating angiogenic factors are related to the severity of gestational hypertension and preeclampsia, and their adverse outcomes

Gestational hypertension (GH) and preeclampsia (PE) are characterized by an imbalance in angiogenic factors. However, the relationship among these factors with the severity of hypertensive disorders of pregnancy (HDP) and adverse outcomes are not fully elucidated. We examined whether these biomarkers are related with the severity of HDP and adverse outcomes.Using a cross-sectional design, serum concentrations of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and soluble endoglin were determined in 764 pregnant women: 75 healthy pregnant, 83 with mild GH (mGH), 105 with severe GH (sGH), 122 with mild PE (mPE), and 379 with severe PE (sPE).All angiogenic factors' concentrations were significantly different (P ≤ 0.041) in HDP than in healthy pregnancy. In addition, these factors were markedly different in sPE than in mPE, sGH, or mGH (P ≤ 0.027) and in patients with sGH that in those with mPE or mGH (P < 0.05). As compared to mGH and mPE, patients with sGH and sPE had higher rates of both preterm delivery at <34 weeks of gestation and small-for-gestational age infants. Moreover, patients with sPE had higher rates of adverse maternal outcomes (P < 0.001) when compared to patients with mGH, sGH, or mPE. In all cases, levels of sFlt-1/PlGF ratio were significantly higher in patients with sGH and sPE who had adverse perinatal and maternal outcomes than in those with sGH and sPE who did not (P ≤ 0.016).Circulating concentrations of angiogenic factors appear to be suitable markers to assess the severity of GH and PE, and adverse outcomes.

Global "omics" evaluation of human placental responses to preeclamptic conditions

BACKGROUND

Preeclampsia (PE) is a leading cause of maternal death. Its cause is still debated but there is general agreement that the placenta plays a central role. Perhaps the most commonly proposed contributors to PE include placental hypoxia, oxidative stress, and increased proinflammatory cytokines. How the placenta responds to these abnormalities has been considered but not as part of a comprehensive analysis of low-molecular-weight biomolecules and their responses to these accepted PE conditions.

OBJECTIVE

Using a peptidomic approach, we sought to identify a set of molecules exhibiting differential expression in consequence of provocative agents/chemical mediators of PE applied to healthy human placental tissue.

STUDY DESIGN

Known PE conditions were imposed on normal placental tissue from 13 uncomplicated pregnancies and changes in the low-molecular-weight peptidome were evaluated. A t test was used to identify potential markers for each imposed stress. These markers were then submitted to a least absolute shrinkage and selection operator multinomial logistic regression model to identify signatures specific to each stressor. Estimates of model performance on external data were obtained through internal validation.

RESULTS

A total of 146 markers were increased/decreased as a consequence of exposure to proposed mediators of PE. Of these 75 changed with hypoxia; 23 with hypoxia-reoxygenation/oxidative stress and 48 from exposure to tumor necrosis factor-α. These markers were chemically characterized using tandem mass spectrometry. Identification rates were: hypoxia, 34%; hypoxia-reoxygenation, 60%; and tumor necrosis factor-α, 50%. Least absolute shrinkage and selection operator modeling specified 16 markers that effectively distinguished all groups, ie, the 3 abnormal conditions and control. Bootstrap estimates of misclassification rates, multiclass area under the curve, and Brier score were 0.108, 0.944, and 0.160, respectively.

CONCLUSION

Using this approach we found previously unknown molecular changes in response to individual PE conditions that allowed development biomolecular signatures for exposure to each accepted pathogenic condition.

The association between angiogenic markers and fetal sex: Implications for preeclampsia research

OBJECTIVE

Current research suggests sexual dimorphism between the male and female fetoplacental units, but with unknown relevance for preeclampsia. We investigated the association between fetal sex and concentrations of the angiogenic markers soluble Fms-like kinase 1 (sFlt-1), placental growth factor (PlGF), and sFlt-1/PlGF ratio in first and second-third trimester in women with/without preeclampsia, and the impact of fetal sex on the prognostic value of angiogenic markers for preeclampsia.

STUDY DESIGN

Observational study in a prospective, population-based cohort of 2110 singleton pregnancies with 150 preeclampsia cases.

RESULTS

Higher sFlt-1 concentrations were observed for women carrying female fetuses in first trimester (all, 1107.65 vs. 992.27pg/ml; preeclampsia cases, 1118.79 vs. 934.49pg/ml, p<0.05) and in second-third trimester (all, 1130.03 vs. 1043.15pg/ml; preeclampsia, 1480.30 vs. 1152.86pg/ml, p<0.05), with similar findings for the sFlt-1/PlGF ratio concentrations in first (29.67 vs. 27.39 p<0.05) and second-third trimester (3.56 vs. 3.22, p<0.05). In first trimester, log transformed concentrations of PlGF, sFlt-1 and sFlt-1/PlGF (all participants) and sFlt-1 (preeclampsia cases) associated with fetal sex in adjusted analyses (p<0.05). In second-third trimester, only log(sFlt-1) associated with fetal sex (all, p=0.028; preeclampsia, p=0.067) In receiver operating curve analysis, prediction of early-onset preeclampsia by sFlt-1/PlGF tended to be superior in pregnancies with female vs. male fetuses (p=0.06).

CONCLUSION

Sexual dimorphism was observed for concentrations of angiogenic markers. Female fetal sex was associated to higher sFlt-1 and sFlt-1/PlGF ratio concentrations in both healthy pregnancies and women developing preeclampsia. Fetal sex should be considered in research and clinical use of angiogenic markers.

Analysis of changes in maternal circulating angiogenic factors throughout pregnancy for the prediction of preeclampsia

OBJECTIVE

To assess whether changes in maternal angiogenic factors throughout pregnancy predict the development of preeclampsia.

STUDY DESIGN

Placental growth factor (PlGF) and soluble fms-like tyrosine kinase 1 receptor (sFlt-1) were measured in 2355 women at 10, 18, 26 and 35 weeks gestation. Receiver operator characteristic analysis was used to calculate test characteristics for changes in analytes between time points. Linear mixed-effects models generated slopes of analytes throughout pregnancy, which in turn were used as predictors in adjusted logistic regression models.

RESULT

Changes in analytes yielded positive predictive values of 9 to 19% and negative predictive values of 93 to 97%. Individuals with lowest quartile slopes in PlGF had sixfold greater odds (95% confidence interval (CI): 3.5, 10.2) of preeclampsia compared with individuals in the highest quartile. With respect to sFlt-1, the highest quartile had 5.1 times greater odds (95% CI: 3.1, 8.4) than the lowest quartile.

CONCLUSION

Measuring the trend in PlGF and sFlt-1 across pregnancy segregates women at increased risk of preeclampsia. However, changes in these factors throughout pregnancy lack clinically useful predictive power.

Preeclampsia and superimposed preeclampsia: The same disease? The role of angiogenic biomarkers

OBJECTIVE

We aimed to compare sFlt-1 and placental growth factor (PlGF) levels and the sFlt-1/PlGF ratio between women with preeclampsia and superimposed preeclampsia to, respectively, normotensive and chronic hypertensive ones.

STUDY DESIGN

We performed a prospective two-armed cohort in a tertiary teaching hospital in Sao Paulo, Brazil, including 37 normotensive and 60 chronic hypertensive pregnant women. We assessed the serum levels of sFlt-1 and PlGF at 20, 26, 32, and 36 gestational weeks by enzyme-linked immunosorbent assay.

MAIN OUTCOME MEASURES

Having preeclampsia and superimposed preeclampsia.

RESULTS

Among normotensive and chronic hypertensive pregnancies, 4 (10.8%) and 14 (23.3%) women developed preeclampsia and superimposed preeclampsia, respectively. Compared with those who remained normotensive, the preeclampsia women presented higher sFlt-1 levels at 32 gestational weeks (4323.45 pg/mL vs. 2242.04 pg/mL, p = 0.019), lower PlGF levels at 20 (183.54 pg/mL vs. 337.38 pg/mL, p = 0.034), 32 (169.69 pg/mL vs. 792.53 pg/mL, p = 0.001), and 36 gestational weeks (252.99 pg/mL vs. 561.81 pg/mL, p = 0.029), and higher sFlt-1/PlGF ratios at 26 (9.02 vs. 1.84, p = 0.004), 32 (23.61 vs. 2.55, p = 0.001), and 36 gestational weeks (49.02 vs. 7.34, p = 0.029). On the other hand, compared with those who remained chronic hypertensive, the superimposed preeclampsia women only presented a higher sFlt-1/PlGF ratio at 32 gestational weeks (9.98 vs. 2.51, p = 0.039).

CONCLUSION

Although angiogenic imbalance is clearly related to preeclampsia, it seems to play a more modest role in superimposed preeclampsia, in which other mechanisms should also be investigated.

A Role of sFlt-1 in Oxidative Stress and Apoptosis in Human and Mouse Pre-Eclamptic Trophoblasts

Pre-eclampsia (PE) is a hypertensive disorder that occurs during pregnancy, and is a multifactorial disease. The antiangiogenic factor, soluble fms-like tyrosine kinase 1 (sFlt-1), has been reported to be important in the pathogenesis of PE, but the mechanism of its involvement remains unknown. To test the effects of sFlt-1 on pregnancy, we injected pregnant mice with exogenous mouse sFlt-1. After 18 days of gestation, higher blood pressure, proteinuria, and histological differences were observed compared with controls. Mitochondrial swelling inside the trophoblast cells in the placenta of sFlt-1-treated pregnant mice was observed by electron microscopy, which suggested a role of sFlt-1 in oxidative stress in trophoblasts in PE. Furthermore, apoptosis markers were upregulated in sFlt-1-treated mice. In conclusion, sFlt-1 appears to play a role in oxidative stress, which promotes apoptosis of trophoblasts. This may be an important mechanism in the development of PE.

Circulating Levels of sFlt1 Splice Variants as Predictive Markers for the Development of Preeclampsia

Angiogenic biomarkers, including soluble fms-like tyrosine kinase 1 (sFlt1), are thought to be predictors of preeclampsia onset; however, improvement is needed before a widespread diagnostic test can be utilized. Here we describe the development and use of diagnostic monoclonal antibodies specific to the two main splice variants of sFlt1, sFlt1-1 and sFlt1-14. These antibodies were selected for their sensitivity and specificity to their respective sFlt1 isoform in a capture ELISA format. Data from this pilot study suggest that sFlt1-1 may be more predictive of preeclampsia than total sFlt1. It may be possible to improve current diagnostic platforms if more specific antibodies are utilized.

Circulating Angiogenic Factors and the Risk of Preeclampsia in Systemic Lupus Erythematosus Pregnancies

OBJECTIVE

To investigate whether angiogenic factors are associated with risk of developing preeclampsia in pregnant women with systemic lupus erythematosus (SLE).

METHODS

We performed a nested case-control study within a cohort of SLE women with singleton pregnancies. The study included 42 patients with SLE who eventually developed preeclampsia and 75 normal SLE pregnancies. Serum samples were collected at 4-week intervals (from weeks 12 to 36). Serum samples were analyzed for soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF), and soluble endoglin (sEng).

RESULTS

Women destined to develop preeclampsia had lower PlGF levels and higher sFlt-1 and sEng levels, and a higher sFlt-1/PlGF ratio than normal pregnancies. These changes became significant at 12 weeks in patients destined to develop either early onset (< 34 weeks, p ≤ 0.003) or late-onset preeclampsia (≥ 34 weeks, p ≤ 0.02). The risk to develop preeclampsia was higher among patients with PlGF concentration values in the lowest quartile or with sFlt-1 and sEng levels, and sFlt-1/PlGF ratio, in the highest quartile of the normal SLE pregnancies distribution. The OR were higher and appeared earlier in patients destined to develop early onset preeclampsia (OR ≥ 16.2, from Week 12 onward) than in patients who presented preeclampsia later (OR ≥ 8.9, from Week 24 onward).

CONCLUSION

Changes in circulating concentrations of sFlt-1, PlGF, sEng, and the sFlt-1/PlGF ratio precede the onset of preeclampsia in SLE pregnancies. The risk profile of circulating angiogenic factors for developing preeclampsia distinctly evolves depending on whether this condition is manifested earlier or later.

Sildenafil Inhibits Advanced Glycation End Products-induced sFlt-1 Release Through Upregulation of Heme Oxygenase-1

Objectives

We examined the effect of sildenafil citrate on advanced glycation end products (AGEs)-induced soluble fms-like tyrosine kinase 1 (sFlt-1) release in JEG-3 choriocarcinoma cells.

Methods

Cells were incubated with control bovine serum albumin (BSA) or AGEs-BSA, and expression of sFlt-1 mRNA and protein release was determined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. AGEs-BSA increased sFlt-1 mRNA expression and protein release in a dose-dependent manner.

Results

Sildenafil citrate suppressed sFlt-1 mRNA expression and protein release in cells treated with AGEs-BSA in a dose-dependent manner. Likewise, it inhibited the increase of reactive oxygen species (ROS) production and NF-κB activity in these cells. Cobalt protoporphyrin (CoPP) and bilirubin also inhibited sFlt-1 release and ROS production in cells treated with AGEs-BSA, whereas zinc protoporphyrin IX (ZnPP IX) antagonized the effect of sildenafil citrate. In cells transfected with the heme oxygenase-1 (HO-1) siRNA, sildenafil citrate failed to inhibit the sFlt-1 release and ROS production.

Conclusion

These results strongly suggest that sildenafil citrate inhibits sFlt-1 release and ROS production in cells treated with AGEs-BSA through upregulation of the HO-1 expression in JEG-3 cells.

Second- and third-trimester biochemical and ultrasound markers predictive of ischemic placental disease

Ischemic placental disease is a recently coined term that describes the vascular insufficiency now believed to be an important etiologic factor in preeclampsia, intrauterine fetal growth restriction, and placental abruption. Given the increased risk for poor maternal and fetal outcomes, early prediction and prevention of this disorder is of significant clinical interest for many. In this article, we review the second- and third-trimester serum and ultrasound markers predictive of ischemic placental disease. Limited first-trimester data is also presented. While current studies report a statistical association between marker levels and various adverse perinatal outcomes, the observed diagnostic accuracy is below the threshold required for clinical utility. An exception to this generalization is uterine artery Doppler for the prediction of early-onset preeclampsia. Metabolomics is a relatively new analytic platform that holds promise as a first-trimester marker for the prediction of both early- and late-onset preeclampsia.

Circulating Angiogenic Factors and Urinary Prolactin as Predictors of Adverse Outcomes in Women With Preeclampsia

Preeclampsia is characterized by an imbalance in angiogenic factors. Urinary prolactin (PRL) levels and its antiangiogenic PRL fragments have been associated with disease severity. In this study, we assessed whether these biomarkers are associated with an increased risk of adverse maternal and perinatal outcomes in preeclamptic women. We studied 501 women with preeclampsia attended at a tertiary care hospital. Serum concentrations of soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF), and soluble endoglin (sEng), as well as urinary PRL levels, were measured by enzymed-linked immunosorbent assay. Antiangiogenic PRL fragments were determined by immunoblotting. The risk for any adverse maternal outcome and for having a small-for-gestational-age infant was higher among women with sFlt-1/PlGF ratios, sEng, and urinary PRL level values in the highest quartile (odds ratios ≥2.7), compared with the lowest quartile. Both urinary PRL levels and the presence of antiangiogenic PRL fragments were more closely associated with the risk of specific adverse maternal outcomes (placental abruption, hepatic hematoma or rupture, acute renal failure, pulmonary edema, maternal death, and need for endotracheal intubation, positive inotropic drug support, and hemodialysis; odds ratios ≥5.7 and ≥4.7, respectively) than either sFlt-1/PlGF ratio or sEng alone. We concluded that in preeclamptic women at the time of initial evaluation, sFlt-1/PlGF ratio and sEng are associated with increased risk of combined adverse maternal outcomes. However, urinary PRL concentrations and its antiangiogenic fragments appear to be better predictors of an adverse maternal outcome and may be useful for risk stratification in preeclampsia.