Gestational angiogenic biomarker patterns in high risk preeclampsia groups

Preeclampsia at term can be classified into 2 clusters with different clinical characteristics and outcomes based on angiogenic biomarkers in maternal blood

BACKGROUND

An antiangiogenic state has emerged as a mechanism of disease in preeclampsia. Angiogenic biomarkers are used in the risk assessment of this syndrome, particularly of early disease. The role of an antiangiogenic state in late preeclampsia is unclear.

OBJECTIVE

This study aimed to determine the prevalence, characteristics, and clinical significance of angiogenic/antiangiogenic factor abnormalities in women with preeclampsia stratified according to gestational age at delivery.

STUDY DESIGN

Two studies were conducted: (1) a longitudinal nested case-control study comprising women with preeclampsia (n=151) and a control group (n=540); and (2) a case series of patients with preeclampsia (n=452). In patients with preeclampsia, blood was collected at the time of diagnosis. Plasma concentrations of placental growth factor and soluble fms-like tyrosine kinase-1 were determined by enzyme-linked immunosorbent assays. An abnormal angiogenic profile was defined as a plasma ratio of placental growth factor and soluble fms-like tyrosine kinase-1 expressed as a multiple of the median <10th percentile for gestational age based on values derived from the longitudinal study. The proportion of patients diagnosed with preeclampsia who had an abnormal angiogenic profile was determined in the case-series participants and stratified by gestational age at delivery into early (≤34 weeks), intermediate (34.1-36.9 weeks), and term (≥37 weeks) preeclampsia. The demographics, clinical characteristics, and pregnancy outcomes of women with preeclampsia with and without an abnormal angiogenic profile were compared.

RESULTS

The prevalence of an abnormal angiogenic profile was higher in preterm than in term preeclampsia (for early, intermediate, and term in the case-control study: 90%, 100%, and 39%; for the case series: 98%, 80%, and 55%, respectively). Women with preeclampsia at term who had an abnormal angiogenic profile were more frequently nulliparous (57% vs 35%), less likely to smoke (14% vs 26%), at greater risk for maternal (14% vs 5%) or neonatal (7% vs 1%) complications, and more often had placental lesions consistent with maternal vascular malperfusion (42% vs 23%; all, P<.05) than those without an abnormal profile. Women with preeclampsia at term who had a normal angiogenic profile had a higher frequency of chronic hypertension (36% vs 21%) and were more likely to have class ≥2 obesity (41% vs 23%) than those with an abnormal profile (both, P<.05).

CONCLUSION

Patients with early preeclampsia had an abnormal angiogenic profile in virtually all cases, whereas only 50% of women with preeclampsia at term had such abnormalities. The profile of angiogenic biomarkers can be used to classify patients with preeclampsia at term, on the basis of mechanisms of disease, into 2 clusters, which have different demographics, clinical characteristics, and risks of adverse maternal and neonatal outcomes. These findings provide a simple approach to classify preeclampsia at term and have implications for future clinical care and research.

Circulating Angiogenic Factor Levels in Hypertensive Disorders of Pregnancy

BACKGROUND: Among women with hypertensive disorders of pregnancy, biomarkers may stratify risk for developing preeclampsia with severe features (sPE). METHODS: Across 18 U.S. centers, we prospectively measured the ratio of serum soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) in pregnant women hospitalized between 23 and 35 weeks of gestation. The primary outcome was predicting sPE, and secondary outcomes included predicting adverse outcomes within 2 weeks. The prognostic performance of the sFlt-1:PlGF ratio was assessed by using a derivation/validation design. RESULTS: A total of 1014 pregnant women were evaluated; 299 were included in the derivation cohort and 715 in the validation cohort. In the derivation cohort, the median sFlt-1:PlGF ratio was 200 (interquartile range, 53 to 458) among women who developed sPE compared with 6 (interquartile range, 3 to 26) in those who did not (P<0.001). The discriminatory ratio of ≥40 was then tested in the validation cohort and yielded a 65% positive (95% confidence interval [CI], 59 to 71) and a 96% negative (95% CI, 93 to 98) predictive value for the primary outcome. The ratio performed better than standard clinical measures (area under the receiver-operating characteristic curve, 0.92 versus <0.75 for standard-of-care tests). Compared with women with a ratio <40, women with a ratio ≥40 were at higher risk for adverse maternal outcomes (16.1% versus 2.8%; relative risk, 5.8; 95% CI, 2.8 to 12.2). CONCLUSIONS: In women with a hypertensive disorder of pregnancy presenting between 23 and 35 weeks of gestation, measurement of serum sFlt-1:PlGF provided stratification of the risk of progressing to sPE within the coming fortnight. (Funded by Cedars-Sinai Medical Center and Thermo Fisher Scientific; ClinicalTrials.gov NCT03815110.)

Proteinuria during pregnancy: definition, pathophysiology, methodology, and clinical significance

Qualitative and quantitative measurement of urine protein excretion is one of the most common tests performed during pregnancy. For more than 100 years, proteinuria was necessary for the diagnosis of preeclampsia, but recent guidelines recommend that proteinuria is sufficient but not necessary for the diagnosis. Still, in clinical practice, most patients with gestational hypertension will be diagnosed as having preeclampsia based on the presence of proteinuria. Although the reference standard for measuring urinary protein excretion is a 24-hour urine collection, spot urine protein-to-creatinine ratio is a reasonable "rule-out" test for proteinuria. Urine dipstick screening for proteinuria does not provide any clinical benefit and should not be used to diagnose proteinuria. The classic cutoff cited to define proteinuria during pregnancy is a value of >300 mg/24 hours or a urine protein-to-creatinine ratio of at least 0.3. Using this cutoff, the rate of isolated proteinuria in pregnancy may reach 8%, whereas preeclampsia occurs among 3% to 8% of pregnancies. Although this threshold is widely accepted, its origin is not based on evidence on adverse pregnancy outcomes but rather on expert opinion and results of small studies. After reviewing the available data, the most important factor that influences maternal and neonatal outcome is the severity of blood pressures and presence of end organ damage, rather than the excess protein excretion. Because the management of gestational hypertension and preeclampsia without severe features is almost identical in frequency of surveillance and timing of delivery, the separation into 2 disorders is unnecessary. If the management of women with gestational hypertension with a positive assessment of proteinuria will not change, we believe that urine assessment for proteinuria is unnecessary in women who develop new-onset blood pressure at or after 20 weeks' gestation. Furthermore, we do not recommend repeated measurement of proteinuria for women with preeclampsia, the amount of proteinuria does not seem to be related to poor maternal and neonatal outcomes, and monitoring proteinuria may lead to unindicated preterm deliveries and related neonatal complications. Our current diagnosis of preeclampsia in women with chronic kidney disease may be based on a change in protein excretion, a baseline protein excretion evaluation is critical in certain conditions such as chronic hypertension, diabetes, and autoimmune or other renal disorders. The current definition of superimposed preeclampsia possesses a diagnostic dilemma, and it is unclear whether a change in the baseline proteinuria reflects another systemic disease such as preeclampsia or whether women with chronic disease such as chronic hypertension or diabetes will experience a different "normal" pattern of protein excretion during pregnancy. Finally, limited data are available regarding angiogenic and other biomarkers in women with chronic kidney disease as a potential aid in distinguishing the worsening of baseline chronic kidney disease and chronic hypertension from superimposed preeclampsia.

Chronic hypertension and superimposed preeclampsia: screening and diagnosis

Superimposed preeclampsia complicates about 20% of pregnancies in women with chronic hypertension and is associated with increased maternal and perinatal morbidity compared with preeclampsia alone. Distinguishing superimposed preeclampsia from chronic hypertension can be challenging because, in chronic hypertension, the traditional criteria for the diagnosis of preeclampsia, hypertension, and significant proteinuria can often predate the pregnancy. Furthermore, the prevalence of superimposed preeclampsia is unlikely to be uniformly distributed across this high-risk group but is related to the severity of preexisting endothelial dysfunction. This has led to interest in identifying biomarkers that could help in screening and diagnosis of superimposed preeclampsia and in the stratification of risk in women with chronic hypertension. Elevated levels of uric acid and suppression of other renal biomarkers, such as the renin-angiotensin aldosterone system, have been demonstrated in women with superimposed preeclampsia but perform only modestly in its prediction. In addition, central to the pathogenesis of preeclampsia is a tendency toward an antiangiogenic state thought to be triggered by an impaired placenta and, ultimately, contributing to the endothelial dysfunction pathognomonic of the disease. In the general obstetrical population, angiogenic factors, such as soluble fms-like tyrosine kinase-1 and placental growth factor, have shown promise in the prediction of preeclampsia. However, soluble fms-like tyrosine kinase-1 and placental growth factor are impaired in women with chronic hypertension irrespective of whether they develop superimposed preeclampsia. Therefore, the differences in levels are less discriminatory in the prediction of superimposed preeclampsia compared with the general obstetrical population. Alternative biomarkers to the angiogenic and renal factors include those of endothelial dysfunction. A characteristic of both preeclampsia and chronic hypertension is an exaggerated systemic inflammatory response causing or augmenting endothelial dysfunction. Thus, proinflammatory mediators, such as tumor necrosis factor-α, interleukin-6, cell adhesion molecules, and endothelin, have been investigated for their role in the screening and diagnosis of superimposed preeclampsia in women with chronic hypertension. To date, the existing limited evidence suggests that the differences between those who develop superimposed preeclampsia and those who do not are, as with angiogenic factors, also modest and not clinically useful for the stratification of women with chronic hypertension. Finally, pro-B-type natriuretic peptide is regarded as a sensitive marker of early cardiac dysfunction that, in women with chronic hypertension, may predate the pregnancy. Thus, it has been proposed that pro-B-type natriuretic peptide could give insight as to the ability of women with chronic hypertension to adapt to the hemodynamic requirements of pregnancy and, subsequently, their risk of developing superimposed preeclampsia. Although higher levels of pro-B-type natriuretic peptide have been demonstrated in women with superimposed preeclampsia compared with those without, current evidence suggests that pro-B-type natriuretic peptide is not a predictor for the disease. The objectives of this review are to, first, discuss the current criteria for the diagnosis of superimposed preeclampsia and, second, to summarize the evidence for these potential biomarkers that may assist in the diagnosis of superimposed preeclampsia.

Administration of recombinant human placental growth factor decreases blood pressure in obese hypertensive pregnant rats

OBJECTIVES

Although epidemiological studies have shown that obesity is associated with increased incidence of hypertension during pregnancy, the mechanisms linking these two comorbidities are not as well studied. Previous investigations detected lower levels of the anti-hypertensive and pregnancy-related factor, placental growth factor (PlGF), in obese hypertensive pregnancies. Therefore, we examined whether obese hypertensive pregnant rats have reduced PlGF and whether increasing its levels by administering recombinant human (rh)PlGF reduces their blood pressure.

METHODS

We utilized a genetic model of obesity characterized to be heavier, hypertensive and fertile, namely rats having heterozygous deficiency of the melanocortin-4 receptor (MC4R-def).

RESULTS

MC4R-def obese rats had lower circulating levels of PlGF than wild-type lean controls at gestational day 19. Also, assessment of the PlGF receptor, Flt-1, in the vasculature showed that its levels were reduced in aorta and kidney glomeruli but increased in small mesenteric arteries. Chronic intraperitoneal administration of rhPlGF from gestational day 13-19 significantly increased circulating PlGF levels in both obese and lean rats, but reduced blood pressure only in the obese pregnant group. The rhPlGF treatment did not alter maternal body and fat masses or circulating levels of the adipokines, leptin and adiponectin. In addition, this treatment did not impact average foetal weights but increased placental weights regardless of obese or lean pregnancy.

CONCLUSION

PlGF is reduced in MC4R-def obese hypertensive pregnant rats, which is similar to findings in obese hypertensive pregnant women, while increasing its levels with exogenous rhPlGF reduces their blood pressure.

Gestational Age-Specific Reference Ranges for the sFlt-1/PlGF Immunoassay Ratio in Twin Pregnancies

OBJECTIVE

Establish reference ranges for the Elecsys® soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) immunoassay ratio in twin pregnancies.

METHODS

Data analyzed were from 3 prospective studies: Prediction of Short-Term Outcome in Pregnant Women with Suspected Preeclampsia (PE) (PROGNOSIS), Study of Early-onset PE in Spain (STEPS), and a multicenter case-control study. Median, 5th, and 95th percentiles for sFlt-1, PlGF, and the sFlt-1/PlGF ratios were determined for normal twin pregnancies for 7 gestational windows and compared with the previous data for singleton pregnancies.

RESULTS

The reference range analysis included 269 women with normal twin pregnancies. Before 29 weeks' gestation, median, 5th, and 95th percentiles for sFlt-1/PlGF ratios did not differ between twin and singleton pregnancies. From 29 weeks' gestation to delivery, median, 5th, and 95th percentiles for sFlt-1/PlGF ratios were substantially higher in twin versus singleton pregnancies. sFlt-1 values were higher in women with twin pregnancies across all gestational windows. PlGF values were similar or higher in twin versus singleton pregnancies; PlGF concentrations increased from 10 weeks + 0 days to 28 weeks + 6 days' gestation.

CONCLUSIONS

Reference ranges for the sFlt-1/PlGF ratio are similar in women with twin and singleton pregnancies until 29 weeks' gestation but appear higher in twin pregnancies thereafter.

Preeclampsia Among African American Pregnant Women: An Update on Prevalence, Complications, Etiology, and Biomarkers

Importance

Preeclampsia is a devastating disease of pregnancy associated with increased risk of fetal and maternal complications. African American pregnant women have a high prevalence of preeclampsia, but there is a need of systemic analyses of this high-risk group regarding complications, etiology, and biomarkers.

Objective

The aim of this study was to provide a synopsis of current research of preeclampsia specifically related to African American women.

Evidence Acquisition

A comprehensive search was performed in the bibliographic database PubMed with keywords "preeclampsia" and "African American."

Results

African American women with preeclampsia were at an increased risk of preterm birth, which resulted in low-birth-weight infants. Intrauterine fetal death among African American preeclamptic patients occurs at twice the rate as in other races. On the maternal side, African American mothers with preeclampsia have more severe hypertension, antepartum hemorrhage, and increased mortality. Those who survive preeclampsia have a high risk of postpartum cardiometabolic disease. Preexisting conditions (eg, systemic lupus erythematosus) and genetic mutations (eg, sickle cell disease in the mother, FVL or APOL1 mutations in the fetus) may contribute to the higher prevalence and worse outcomes in African American women. Many blood factors, for example, the ratio of proteins sFlt/PlGF, hormones, and inflammatory factors, have been studied as potential biomarkers for preeclampsia, but their specificity needs further investigation.

Conclusions

Further studies of preeclampsia among African American women addressing underlying risk factors and etiologies, coupled with identification of preeclampsia-specific biomarkers allowing early detection and intervention, will significantly improve the clinical management of this devastating disease.

Sleep Disordered Breathing, a Novel, Modifiable Risk Factor for Hypertensive Disorders of Pregnancy

PURPOSE OF REVIEW

Pathophysiology of hypertensive disorders of pregnancy (HDP), especially preeclampsia, has not been fully elucidated. Most trials aimed at the prevention of preeclampsia have failed to show significant benefit and investigation of novel, modifiable risk factors is sorely needed. Sleep disordered breathing (SDB), a group of disorders for which treatments are available, meets these criteria. SDB impacts about a third of all pregnancies and is associated with hypertension in the general non-pregnant population.

RECENT FINDINGS

Recent studies have shown a high prevalence of SDB, especially in complicated pregnancies. Several studies have shown that pregnant women with SDB have a higher risk for developing HDP, and these two disorders are associated with similar maternal long-term cardiovascular outcomes. Based on limited animal models of gestational intermittent hypoxia and human studies, SDB and HDP share similar risk factors and some pathophysiological mechanisms. However, there is paucity of studies addressing causality of this association and identifying therapeutic targets for intervention. Maternal SDB represents a novel and modifiable risk factor of HDP. Further studies are needed in order to establish the exact mechanisms underlying this association and to identify specific areas for clinical interventions.

The role of biomarkers in predicting pre-eclampsia in high-risk women

Background

There are limited data on performance of biomarkers to predict pre-eclampsia (PE) in high-risk women. This study investigated the ability of FABP4, PAPP-A, PlGF, sFlt-1 and sEng to predict PE in a high-risk group.

Methods

Non-fasting samples were analysed at 11 + 0–13 + 6 (V1) and 19 + 0–21 + 6 weeks (V2) ( n = 195). Logistic regression models were determined. Area under (AUC) the receiver operating characteristic (ROC) curve analysis was performed. The added value of biomarkers to clinical characteristics for PE prediction was quantified using integrated discrimination improvement (IDI) and net reclassification improvement (NRI) indices.

Results

Prevalence of PE was 12%. Lower concentrations of sFlt-1:PlGF (V1) and PlGF and PlGF:sEng (V2) were seen in women who developed PE. Controlling for baseline characteristics (V1), a doubling of sFlt-1 (pg/mL) (median 896.0, IQR 725.5–1097.0) and sFlt-1:PlGF (median 21.2, IQR 14.7–32.3) was associated with reduction in odds of PE (OR 0.20, 95% CI 0.06–0.65, P = 0.007 and OR 0.48, 95% CI 0.25–0.92, P = 0.04). Addition of sFlt-1 and sFlt-1:PlGF to baseline characteristics non-significantly improved AUC (0.74) (AUC 0.77, P = 0.40 and 0.76, P = 0.39). NRI and IDI analyses confirmed added clinical utility of sFlt-1 (NRI = 0.539, P = 0.01 and IDI = 0.052, P = 0.03). In V2, doubling of PlGF:sEng (median 71.9, IQR 47.0–102.8) was associated with reduction in the risk of PE (OR 0.56, 95% CI 0.35–0.98, P = 0.04). The addition of PlGF:sEng to baseline characteristics non-significantly improved AUC from 0.78 to 0.82 ( P = 0.25) and improved reclassification of cases (NRI = 0.682, P = 0.002).

Conclusions

Screening tests incorporating first trimester sFlt-1 and second trimester PlGF:sEng have potential to aid PE prediction in high-risk pregnancies.

Effect of Low-Dose Aspirin on Soluble FMS-Like Tyrosine Kinase 1/Placental Growth Factor (sFlt-1/PlGF Ratio) in Pregnancies at High Risk for the Development of Preeclampsia

BACKGROUND

Soluble FMS-like Tyrosine Kinase 1 (sFlt-1) and placental growth factor (PlGF) have been reported to be highly predictive several weeks before the onset of preeclampsia.

OBJECTIVE

To investigate longitudinal changes of serum levels sFlt-1 and PlGF in pregnant women at high risk for the development of preeclampsia and to reveal an impact of aspirin on maternal serum concentrations of sFlt-1 and PlGF.

METHODS

This was a prospective longitudinal study in 394 women with various risk factors for the development of preeclampsia (chronic hypertension, antiphospholipid syndrome/APS or systemic lupus erythematosus/SLE, thrombophilia, women with a history of preeclampsia, pathologic first trimester screening for preeclampsia) and 68 healthy women. Serum levels of sFlt-1 and PlGF were measured prospectively at 4-week intervals (from gestational weeks 12 until postpartum).

RESULTS

The sFlt-1/PlGF ratio was significantly higher in women with an adverse obstetric outcome compared to women with a normal pregnancy, starting between 20 and 24 weeks of gestation. There was no effect of aspirin on sFlt-1/PlGF ratio in women with chronic hypertension, APS/SLE, thrombophilia and controls. The use of aspirin showed a trend towards an improvement of the sFlt-1/PlGF ratio in women with preeclampsia in a previous pregnancy and a significant effect on the sFlt-1/PlGF ratio in women with a pathologic first trimester screening for preeclampsia.

CONCLUSIONS

Our findings reveal an impact of aspirin on sFlt-1/PlGF ratio in women with a pathologic first trimester screening for preeclampsia, strongly supporting its prophylactic use.

Preeclampsia: Maternal Systemic Vascular Disorder Caused by Generalized Endothelial Dysfunction Due to Placental Antiangiogenic Factors

Preeclampsia, a systemic vascular disorder characterized by new-onset hypertension and proteinuria after 20 weeks of gestation, is the leading cause of maternal and perinatal morbidity and mortality. Maternal endothelial dysfunction caused by placental factors has long been accepted with respect to the pathophysiology of preeclampsia. Over the past decade, increased production of placental antiangiogenic factors has been identified as a placental factor leading to maternal endothelial dysfunction and systemic vascular dysfunction. This review summarizes the recent advances in understanding the molecular mechanisms of endothelial dysfunction caused by placental antiangiogenic factors, and the novel clinical strategies based on these discoveries.

Preeclampsia: A close look at renal dysfunction

Preeclampsia (PE) is a unique pathophysiologic situation that physiologic interests of mother, fetus, and placenta diverge. PE is related to the increased circulating antiangiogenic factors originated from hypoxic placenta. It is simply defined by the new onset of hypertension (≥140/90 mmHg) and proteinuria (≥0.3 g/day) after 20 weeks of gestation. PE is associated with kidney dysfunction due to deficiency in podocyte specific vascular endothelial growth factor (VEGF). Hypoxic placenta in PE patients produces increased levels of fms-like tyrosine kinase 1(sFlt-1), a soluble receptor of VEGF. sFlt-1 abrogates binding of VEGF to its receptor on endothelial cells and podocytes, and ultimately damages the filtration barrier. Glomerular endotheliosis and thrombotic microangiopathy (TMA) are the main features of kidney involvement in PE and can induce clotting and vessel occlusion. This complex pathophysiology is ameliorated after delivery; however, permanent kidney damages may remain and is intensified thereafter. This review aims to highlight the biochemical, genetic, and immunological-involved factors in the initiation of PE and explores the relationship between the kidney and PE. This work mainly discusses the pathologic mechanisms of kidney involvement in PE through the lens of the imbalanced VEGF-VEGF receptor signaling pathway.

Secretion of heat shock -60, -70 kD protein, IL-1β and TNFα levels in serum of a term normal pregnancy and patients with pre-eclampsia development

The extracellular heat shock proteins (eHsp) family act as molecular chaperones regulating folding, transporting protein and are associated with immune modulation in different physiological and pathological processes. They have been localized in different gestational tissues and their concentration in amniotic fluid and serum has been determined. In the present study, we proposed to determine the concentration of eHsp‐60, ‐70, IL‐1β and TNFα in the serum of pregnant patients with 34 weeks of gestation with and without clinical evidences of preeclampsia (PE). Our results indicate significant increase of these markers in patients with PE with respect to healthy pregnant patients without active labor. Finally, the concentration of eHsp‐60 and ‐70 correlated positively with the hepatic dysfunction markers uric acid, lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT) glutamic pyruvic transaminase (GPT), and inflammatory IL‐1β and TNFα response. In conclusion, our results demonstrate a strong associated between Hsp and marker of hepatic dysfunction.

ELABELA plasma concentrations are increased in women with late-onset preeclampsia

Objective: ELABELA is a newly discovered peptide hormone that appears to be implicated in the mechanisms leading to preeclampsia, independently of angiogenic factors. The aim of the current study was to investigate whether women with early- or late-onset preeclampsia have altered ELABELA plasma concentrations compared to gestational-age-matched normal pregnant women.Methods: This retrospective cross-sectional study focused on the maternal plasma samples collected from 232 women with a singleton pregnancy who were allocated into the following groups: (1) early-onset preeclampsia (<34 weeks of gestation, N = 56); (2) late-onset preeclampsia (≥34 weeks of gestation, N = 57); and (3) gestational-age-matched controls with a normal pregnancy [(<34 weeks of gestation, N = 59); (≥34 weeks of gestation, N = 60)]. ELABELA plasma concentrations were determined using a validated enzyme immunoassay.Results: (1) ELABELA plasma concentrations are higher in patients with late-onset preeclampsia compared with those from gestational-age-matched controls with a normal pregnancy [median: 7.99 ng/mL (IQR, 5.3-13.95 ng/mL) versus median: 4.17 ng/mL (IQR, 3-11.19 ng/mL), p =.001]; (2) ELABELA plasma concentrations in patients with early-onset preeclampsia do not differ from those of normal pregnant women [median: 6.09 ng/mL (IQR, 2.8-10.66 ng/mL) versus median: 4.02 ng/mL (IQR, 3.26-7.49), p = .32]; and (3) ELABELA plasma concentrations are higher in patients with late-onset preeclampsia compared to those with early-onset preeclampsia [median: 7.99 ng/mL (IQR, 5.3-13.95 ng/mL) versus median: 6.09 ng/mL (IQR, 2.8-10.66 ng/mL), p = .01].Conclusion: ELABELA plasma concentrations are higher in patients with late-onset preeclampsia than in those with a normal pregnancy. However, women with early-onset preeclampsia have similar ELABELA plasma concentrations to those with a normal pregnancy. These findings provide insight into the ELABELA axis during the human syndrome of preeclampsia. In addition, these data support the concept that different pathophysiologic mechanisms are implicated in early- and late-onset preeclampsia.

Placental-specific sFLT-1: role in pre-eclamptic pathophysiology and its translational possibilities for clinical prediction and diagnosis

Pre-eclampsia is a common obstetric complication globally responsible for a significant burden of maternal and perinatal morbidity and mortality. Central to its pathophysiology is the anti-angiogenic protein, soluble fms-like tyrosine kinase-1 (sFLT-1). sFLT-1 is released from a range of tissues into the circulation, where it antagonizes the activity of vascular endothelial growth factor and placental growth factor leading to endothelial dysfunction. It is this widespread endothelial dysfunction that produces the clinical features of pre-eclampsia including hypertension and proteinuria. There are multiple splice variants of sFLT-1. One, known as sFLT-1 e15a, evolved quite recently and is only present in humans and higher order primates. This sFLT-1 variant is also the main sFLT-1 secreted from the placenta. Recent work has shown that sFLT-1 e15a is significantly elevated in the placenta and circulation of women with pre-eclampsia. It is also biologically active, capable of causing endothelial dysfunction and the end-organ dysfunction seen in pre-eclampsia. Indeed, the over-expression of sFLT-1 e15a in mice recapitulates the pre-eclamptic phenotype in pregnancy. Therefore, here we propose that sFLT-1 e15a may be the sFLT-1 variant primarily responsible for pre-eclampsia, a uniquely human disease. Furthermore, this placental-specific sFLT-1 variant provides promise for use as an accurate biomarker in the prediction or diagnosis of pre-eclampsia.

Angiogenic factors for prediction of preeclampsia and intrauterine growth restriction onset in high-risk women: AngioPred study

OBJECTIVE

The study aimed to compare the level of two angiogenic factors, soluble fms-like tyrosine kinase-1 (sFlt1) and soluble endoglin (sEng), for the prediction of preeclampsia and intrauterine growth restriction in high-risk pregnant women.

METHODS

A prospective multicenter cohort study of 200 pregnant patients was conducted between June 2008 and October 2010. sFlt1 and sEng were measured by enzyme-linked immunosorbent assay.

RESULTS

Forty-five patients developed a placenta-mediated adverse pregnancy outcome. Plasma levels of sFlt1 and sEng were higher in patients who will experience a preeclampsia at 28, 32, and 36 weeks compared with patients with no complication. The same results were observed for intrauterine growth restriction. Plasma levels of sFlt1 and sEng were not significantly different for patients with preeclampsia compare to patients with intrauterine growth restriction. Patients with early pre-eclampsia (PE) had very high rates of angiogenic factors at 20, 24, and 28 weeks. Patients with late PE and early and late intrauterine growth retardation (IUGR) had high rates at 32 and 36 weeks.

CONCLUSION

In high-risk women, angiogenic factors are disturbed before the onset of preeclampsia and this is true for intrauterine growth restriction.

An intermediate sFlt-1/PlGF ratio indicates an increased risk for adverse pregnancy outcome

OBJECTIVE

The sFlt-1/PlGF ratio is a valid marker in diagnosing or excluding preeclampsia. The currently used cut offs frame an intermediate zone of 33-85 (<34⁰ weeks) or 33-110 (≥34⁰ weeks), respectively. In this study we sought to evaluate the relevance of an intermediate sFlt-1/PlGF ratio for the clinical pregnancy course and outcome.

MATERIAL AND METHODS

We retrospectively analysed 533 consecutive patients with sFlt-1/PlGF ratio measurements for suspected preeclampsia. In patients with an intermediate sFlt-1/PlGF ratio, fetal and maternal characteristics and also pregnancy outcome were documented. Furthermore, we compared the patient groups with <34⁰/34⁰-36⁶/≥37⁰ gestational weeks at first visit.

RESULTS

83/533 (15.6%) patients had an intermediate sFlt-1/PlGF ratio. Maternal or fetal diseases or twin pregnancies occurred in 87.9%. Preeclampsia/HELLP syndrome developed in 31.3% but were mostly mild or moderate (65.4%). However, severe adverse outcome was observed in 36.1% with severe preeclampsia in 10.8%. Even if further pregnancy duration and gestational week correlated negatively (r=-0.424; p<0.001), 92% of patients, tested with <34⁰ weeks delivered prematurely. The overall preterm birth rate was 27.7%.

CONCLUSIONS

Patients with an intermediate sFlt-1/PlGF ratio are at risk for severe adverse outcome. An intermediate sFlt-1/PlGF ratio indicates a risk for preterm birth, independent from the occurrence of preeclampsia.

The prediction of late-onset preeclampsia: Results from a longitudinal proteomics study

BACKGROUND

Late-onset preeclampsia is the most prevalent phenotype of this syndrome; nevertheless, only a few biomarkers for its early diagnosis have been reported. We sought to correct this deficiency using a high through-put proteomic platform.

METHODS

A case-control longitudinal study was conducted, including 90 patients with normal pregnancies and 76 patients with late-onset preeclampsia (diagnosed at ≥34 weeks of gestation). Maternal plasma samples were collected throughout gestation (normal pregnancy: 2-6 samples per patient, median of 2; late-onset preeclampsia: 2-6, median of 5). The abundance of 1,125 proteins was measured using an aptamers-based proteomics technique. Protein abundance in normal pregnancies was modeled using linear mixed-effects models to estimate mean abundance as a function of gestational age. Data was then expressed as multiples of-the-mean (MoM) values in normal pregnancies. Multi-marker prediction models were built using data from one of five gestational age intervals (8-16, 16.1-22, 22.1-28, 28.1-32, 32.1-36 weeks of gestation). The predictive performance of the best combination of proteins was compared to placental growth factor (PIGF) using bootstrap.

RESULTS

1) At 8-16 weeks of gestation, the best prediction model included only one protein, matrix metalloproteinase 7 (MMP-7), that had a sensitivity of 69% at a false positive rate (FPR) of 20% (AUC = 0.76); 2) at 16.1-22 weeks of gestation, MMP-7 was the single best predictor of late-onset preeclampsia with a sensitivity of 70% at a FPR of 20% (AUC = 0.82); 3) after 22 weeks of gestation, PlGF was the best predictor of late-onset preeclampsia, identifying 1/3 to 1/2 of the patients destined to develop this syndrome (FPR = 20%); 4) 36 proteins were associated with late-onset preeclampsia in at least one interval of gestation (after adjustment for covariates); 5) several biological processes, such as positive regulation of vascular endothelial growth factor receptor signaling pathway, were perturbed; and 6) from 22.1 weeks of gestation onward, the set of proteins most predictive of severe preeclampsia was different from the set most predictive of the mild form of this syndrome.

CONCLUSIONS

Elevated MMP-7 early in gestation (8-22 weeks) and low PlGF later in gestation (after 22 weeks) are the strongest predictors for the subsequent development of late-onset preeclampsia, suggesting that the optimal identification of patients at risk may involve a two-step diagnostic process.

Role of angiopoietin-2, endoglin, and placental growth factor in HIV-associated preeclampsia

OBJECTIVE

The factors angiopoeitin-2 (Ang-2), endoglin (Eng), and placental growth factor (PlGF) have been implicated in the pathophysiology of preeclampsia (PE). This study assessed their serum levels in HIV-negative and HIV-positive pregnant normotensive and pre-eclamptic women.

METHODS

Participants were recruited at the antenatal clinic, serum samples were evaluated using the Bioplex Human Cancer Biomarker (panel 2).

RESULTS

Ang-2 and Eng levels were higher, whilst PlGF levels were lower in the PE compared with the normotensive group. Pregnancy type had no significant effect on Ang-2 and showed a significant interaction with Eng (p < 0.0001) and PlGF (p = 0.0033). HIV status had no significant effect on angiopoeitin-2 (p = 0.4), Eng (p = 0.4), and PlGF (p = 0.7) but the levels were slightly higher in the HIV-negative cohort.

CONCLUSIONS

This study demonstrates an elevation of Ang-2 and Eng in pre-eclamptic compared with normotensive pregnant women implicating their role in its pathogenesis.

Blood laboratory testing for early prediction of preeclampsia: chasing the finish line or at the starting blocks?

Preeclampsia (PE) affects 2-8% of pregnancies worldwide, thus representing an important cause of maternal and neonatal morbidity, up to death. Many studies have been designed to identify putative biomarkers for accurate and timely diagnosing PE, but only some of them were focused on specific and sensitive biomarkers for early prediction of this life-threatening condition. In particular, some prospective studies aimed to investigate the predictive role of circulating biomarkers before 20 weeks of gestation in the general pregnant population yielded conflicting results. This article is hence centered on results obtained in studies investigating the predictive performances of angiogenic, anti-angiogenic, inflammatory, endocrine, and epigenetic biomarkers. The available evidence suggests that angiogenic and anti-angiogenic molecules, in particular the sFlt1:PlGF ratio, may be considered the biomarkers with the best diagnostic performance in the second trimester. However, doubts remain about their use in clinical settings before the 20th gestational week. Even lower evidence is available for other biomarkers, due to the fact that some positive results have not been confirmed in ensuing investigations, whereas unresolved analytical issues still contribute to make their clinical reliability rather questionable. Differential expression of microRNAs seems also a promising evidence for early prediction of PE, but additional research and well-designed prospective studies are needed to identify and validate routine predictive tests. KEY MESSAGES Preeclampsia affects 2-8% of pregnant women worldwide, thus remaining one of the leading causes of maternal and neonatal morbidity and mortality. Several studies have investigated the predictive role of circulating biomarkers before 20th week of gestation with conflicting results. Additional research and well-designed prospective studies are needed to identify and validate predictive tests in clinical practice.

Failure of physiologic transformation of spiral arteries, endothelial and trophoblast cell activation, and acute atherosis in the basal plate of the placenta

BACKGROUND

Failure of physiologic transformation of spiral arteries has been reported in preeclampsia, fetal growth restriction, fetal death, and spontaneous preterm labor with intact or ruptured membranes. Spiral arteries with failure of physiologic transformation are prone to develop atherosclerotic-like lesions of atherosis. There are striking parallels between preeclampsia and atherosclerotic disease, and between lesions of atherosis and atherosclerosis. Endothelial activation, identified by intercellular adhesion molecule-1 expression, is present in atherosclerotic-like lesions of heart transplantation, and is considered a manifestation of rejection. Similarly, endothelial activation/dysfunction has been implicated in the pathophysiology of atherosclerosis and preeclampsia. Intercellular adhesion molecule-1-overexpressing-activated endothelial cells are more resistant to trophoblast displacement than nonactivated endothelium, and may contribute to shallow spiral artery trophoblastic invasion in obstetrical syndromes having failure of physiologic transformation.

OBJECTIVE

We sought to determine whether failure of spiral artery physiologic transformation was associated with activation of interstitial extravillous trophoblasts and/or spiral artery endothelium and presence of acute atherosis in the placental basal plate.

STUDY DESIGN

A cross-sectional study of 123 placentas (19-42 weeks' gestation) obtained from normal pregnancies (n = 22), preterm prelabor rupture of membranes (n = 26), preterm labor (n = 23), preeclampsia (n = 27), intrauterine fetal death (n = 15), and small for gestational age (n = 10) was performed. Failure of spiral artery physiologic transformation and presence of cell activation was determined using immunohistochemistry of placental basal plates containing a median of 4 (minimum: 1; maximum: 9) vessels per placenta. Endothelial/trophoblast cell activation was defined by the expression of intercellular adhesion molecule-1. Investigators examining microscopic sections were blinded to clinical diagnosis. Pairwise comparisons among placenta groups were performed with Fisher exact test and Wilcoxon rank sum test using a Bonferroni-adjusted level of significance (.025).

RESULTS

We found that 87% (94/108) of placentas having spiral arteries with failure of physiologic transformation (actin-positive and cytokeratin-negative) in the basal plate, and 0% (0/15) of placentas having only spiral arteries with complete physiologic transformation (cytokeratin-positive and actin-negative), had arterial endothelial and/or interstitial extravillous trophoblasts reactive with the intercellular adhesion molecule-1 activation marker (P < .001). A significant correlation (R² = 0.84) was found between expression of spiral artery endothelial and interstitial extravillous trophoblast intercellular adhesion molecule-1 (P < .001) in activated placentas. Lesions of atherosis were found in 31.9% (30/94) of placentas with complete and/or partial failure of physiologic transformation of spiral arteries that were intercellular adhesion molecule-1-positive, in none of the 14 placentas with failure of physiologic transformation that were intercellular adhesion molecule-1-negative, and in none of the 15 placentas with complete spiral artery physiologic transformation without failure (P = .001). All placentas (30/30, 100%) with atherosis were identified in placentas having concomitant spiral artery endothelial and interstitial extravillous trophoblast activation.

CONCLUSION

Failure of spiral artery physiologic transformation in the placental basal plate is associated with interstitial extravillous trophoblast and arterial endothelial activation along with increased frequency of spiral artery atherosis. These findings may be used to improve the characterization of different disorders of the placental bed such as in refining the existing tools for the early prediction of risk for preterm, preeclamptic, and other abnormal pregnancies.

The use of angiogenic biomarkers in maternal blood to identify which SGA fetuses will require a preterm delivery and mothers who will develop pre-eclampsia

OBJECTIVE

To determine (1) whether maternal plasma concentrations of angiogenic and anti-angiogenic factors can predict which mothers diagnosed with "suspected small for gestational age fetuses (sSGA)" will develop pre-eclampsia (PE) or require an indicated early preterm delivery (≤ 34 weeks of gestation); and (2) whether risk assessment performance is improved using these proteins in addition to clinical factors and Doppler parameters.

METHODS

This prospective cohort study included women with singleton pregnancies diagnosed with sSGA (estimated fetal weight <10th percentile) between 24 and 34 weeks of gestation (n = 314). Plasma concentrations of soluble vascular endothelial growth factor receptor-1 (sVEGFR-1), soluble endoglin (sEng) and placental growth factor (PlGF) were determined in maternal blood obtained at the time of diagnosis. Doppler velocimetry of the umbilical (Umb) and uterine (UT) arteries was performed. The outcomes were (1) subsequent development of PE; and (2) indicated preterm delivery at ≤ 34 weeks of gestation (excluding deliveries as a result of spontaneous preterm labor, preterm pre-labor rupture of membranes or chorioamnionitis).

RESULTS

(1) The prevalence of PE and indicated preterm delivery was 9.2% (n = 29/314) and 7.3% (n = 23/314), respectively; (2) the area under the receiver operating characteristic curve (AUC) for the identification of patients who developed PE and/or required indicated preterm delivery was greater than 80% for the UT artery pulsatility index (PI) z-score and each biochemical marker (including their ratios) except sVEGFR-1 MoM; (3) using cutoffs at a false positive rate of 15%, women with abnormal plasma concentrations of angiogenic/anti-angiogenic factors were 7-13 times more likely to develop PE, and 12-22 times more likely to require preterm delivery than those with normal plasma MoM concentrations of these factors; (4) sEng, PlGF, PIGF/sEng and PIGF/sVEGFR-1 ratios MoM, each contributed significant information about the risk of PE beyond that provided by clinical factors and/or Doppler parameters: women who had low MoM values for these biomarkers were at 5-9 times greater risk of developing PE than women who had normal values, adjusting for clinical factors and Doppler parameters (adjusted odds ratio for PlGF: 9.1, PlGF/sEng: 5.6); (5) the concentrations of sVEGFR-1 and PlGF/sVEGFR-1 ratio MoM, each contributed significant information about the risk of indicated preterm delivery beyond that provided by clinical factors and/or Doppler parameters: women who had abnormal values were at 8-9 times greater risk for indicated preterm delivery, adjusting for clinical factors and Doppler parameters; and (6) for a two-stage risk assessment (Umb artery Doppler followed by Ut artery Doppler plus biochemical markers), among women who had normal Umb artery Doppler velocimetry (n = 279), 21 (7.5%) developed PE and 11 (52%) of these women were identified by an abnormal UT artery Doppler mean PI z-score (>2SD): a combination of PlGF/sEng ratio MoM concentration and abnormal UT artery Doppler velocimetry increased the sensitivity of abnormal UT artery Doppler velocimetry to 76% (16/21) at a fixed false-positive rate of 10% (p = 0.06).

CONCLUSION

Angiogenic and anti-angiogenic factors measured in maternal blood between 24 and 34 weeks of gestation can identify the majority of mothers diagnosed with "suspected SGA" who subsequently developed PE or those who later required preterm delivery ≤ 34 weeks of gestation. Moreover, incorporation of these biochemical markers significantly improves risk assessment performance for these outcomes beyond that of clinical factors and uterine and umbilical artery Doppler velocimetry.

Low-dose aspirin for pre-eclampsia prevention in twins with elevated human chorionic gonadotropin

OBJECTIVE

The objective of the study is to evaluate low-dose aspirin (LDA) for pre-eclampsia prevention in twin gestations with elevated maternal serum human chorionic gonadotropin (hCG).

STUDY DESIGN

Secondary analysis of the Maternal-Fetal Medicine Units High-Risk Aspirin trial for pre-eclampsia prevention. A threshold hCG level for predicting pre-eclampsia was identified in placebo-randomized patients. Pre-eclampsia incidence and time of onset were compared between treatment groups, overall and by hCG threshold category.

RESULTS

Pre-eclampsia incidence was lower with LDA than with placebo (6% vs 16%, OR 0.32, 95% CI 0.12 to 0.82). An hCG threshold of 29.96 IU ml(-1) best predicted pre-eclampsia. In patients with hCG <29.96 IU ml(-1), the differences in pre-eclampsia incidence or time of onset were not significant. In patients with hCG >29.96 IU ml(-1), LDA was associated with lower pre-eclampsia incidence than placebo (6% vs 23%, OR 0.21, 95% CI 0.06 to 0.79) and delayed onset.

CONCLUSION

Twin gestations with elevated hCG levels may benefit from LDA for pre-eclampsia prevention.

Maternal plasma angiogenic index-1 (placental growth factor/soluble vascular endothelial growth factor receptor-1) is a biomarker for the burden of placental lesions consistent with uteroplacental underperfusion: a longitudinal case-cohort study

BACKGROUND

Placental lesions consistent with maternal vascular underperfusion (MVU) are thought to be pathogenically linked to preeclampsia, small-for-gestational-age newborns, fetal death, and spontaneous preterm labor and delivery; yet, these lesions cannot be diagnosed antenatally. We previously reported that patients with such conditions and lesions have an abnormal profile of the angiogenic placental growth factor (PlGF) and antiangiogenic factors (eg, soluble vascular endothelial growth factor receptor [sVEGFR]-1).

OBJECTIVE

The objectives of this study were to: (1) examine the relationship between the maternal plasma PlGF/sVEGFR-1 concentration ratio (referred to herein as angiogenic index-1) and the burden of histologic placental features consistent with MVU; and (2) test the hypothesis that angiogenic index-1 can identify patients in the midtrimester who are destined to deliver before 34 weeks of gestation with multiple (ie, ≥3) histologic placental features consistent with MVU.

STUDY DESIGN

A 2-stage case-cohort sampling strategy was used to select participants from among 4006 women with singleton gestations enrolled from 2006 through 2010 in a longitudinal study. Maternal plasma angiogenic index-1 ratios were determined using enzyme-linked immunosorbent assays. Placentas underwent histologic examination according to standardized protocols by experienced pediatric pathologists who were blinded to clinical diagnoses and pregnancy outcomes. The diagnosis of lesions consistent with MVU was made using criteria proposed by the Perinatal Section of the Society for Pediatric Pathology. Weighted analyses were performed to reflect the parent cohort; "n*" is used to reflect weighted frequencies.

RESULTS

(1) Angiogenic index-1 (PlGF/sVEGFR-1) concentration ratios were determined in 7560 plasma samples collected from 1499 study participants; (2) the prevalence of lesions consistent with MVU was 21% (n* = 833.9/3904) and 27% (n* = 11.4/42.7) of women with ≥3 MVU lesions delivered before 34 weeks of gestation; (3) a low angiogenic index-1 (<2.5th quantile for gestational age) in maternal plasma samples obtained within 48 hours of delivery had a sensitivity of 73% (n* = 8.3/11.4; 95% confidence interval [CI], 47-98%), a specificity of 94% (n* = 3130.9/3316.2; 95% CI, 94-95%), a positive likelihood ratio of 12.2, and a negative likelihood ratio of 0.29 in the identification of patients who delivered placentas with ≥3 MVU lesions at <34 weeks; (4) prospectively, at 20-23 weeks of gestation, a maternal plasma concentration of angiogenic index-1 <2.5th quantile identified 70% (n* = 7.2/10.3; 95% CI, 42-98%) of patients who delivered placentas with ≥3 MVU lesions before 34 weeks (specificity, 97% [n* = 2831.3/2918; 95% CI, 96-98%]; positive likelihood ratio, 23; negative likelihood ratio, 0.31); and (5) among women without obstetrical complications who delivered at term, angiogenic index-1 was lower in women with than without placental lesions consistent with MVU (P < .05).

CONCLUSION

Maternal plasma angiogenic index-1 (PlGF/sVEGFR-1) is the first biomarker for the burden of placental lesions consistent with MVU. We propose that an accumulation of these lesions in placentas delivered before 34 weeks is a histologic counterpart of an antiangiogenic profile.

Is It Possible to Differentiate Chronic Kidney Disease and Preeclampsia by means of New and Old Biomarkers? A Prospective Study

Objective. Chronic kidney disease (CKD) and preeclampsia (PE) may both present with hypertension and proteinuria in pregnancy. Our objective is to test the possibility of distinguishing CKD from PE by means of uteroplacental flows and maternal circulating sFlt-1/PlGF ratio. Design. Prospective analysis. Population. Seventy-six patients (35 CKD, 24 PE, and 17 other hypertensive disorders), with at least one sFlt-1/PlGF and Doppler evaluation after the 20th gestational week. Methods. Maternal sFlt-1-PlGF were determined by immunoassays. Abnormal uterine artery Doppler was defined as resistance index ≥ 0.58. Umbilical Doppler was defined with gestational-age-adjusted Pulsatility Index. Clinical diagnosis was considered as reference. Performance of Doppler study was assessed by sensitivity analysis; sFlt-1/PlGF cut-off values were determined by ROC curves. Results. The lowest sFlt-1/PlGF ratio (8.29) was detected in CKD, the highest in PE (317.32) (P < 0.001). Uteroplacental flows were mostly preserved in CKD patients in contrast to PE (P < 0.001). ROC analysis suggested two cut-points: sFlt-1/PlGF ≥ 32.81 (sensitivity 82.93%; specificity 91.43%) and sFlt-1/PlGF ≥ 78.75 (sensitivity 62.89%, specificity 97.14%). Specificity reached 100% at sFlt-1/PlGF ≥ 142.21 (sensitivity: 48.8%). Early-preterm delivery was associated with higher sFlt-1/PlGF ratio and abnormal uteroplacental flows relative to late-preterm and term deliveries. Conclusions. sFlt-1/PlGF ratio and uteroplacental flows significantly correlated with PE or CKD and preterm delivery.

Baseline placental growth factor levels for the prediction of benefit from early aspirin prophylaxis for preeclampsia prevention

OBJECTIVE

Placental growth factor (PlGF) levels early in pregnancy are lower in women who ultimately develop preeclampsia. Early initiation of low-dose aspirin reduces preeclampsia risk in some high risk women. We hypothesized that low PlGF levels may identify women at increased risk for preeclampsia who would benefit from aspirin.

STUDY DESIGN

Secondary analysis of the MFMU High-Risk Aspirin study including singleton pregnancies randomized to aspirin 60mg/d (n=102) or placebo (n=72), with PlGF collected at 13w 0d-16w 6d. Within the placebo group, we estimated the probability of preeclampsia by PlGF level using logistic regression analysis, then determined a potential PlGF threshold for preeclampsia prediction using ROC analysis. We performed logistic regression modeling for potential confounders.

RESULTS

ROC analysis indicated 87.71pg/ml as the threshold between high and low PlGF for preeclampsia-prediction. Within the placebo group high PlGF weakly predicted preeclampsia (AUC 0.653, sensitivity/specificity 63%/66%). We noted a 2.6-fold reduction in preeclampsia with aspirin in the high-PlGF group (12.15% aspirin vs 32.14% placebo, p=0.057), but no significant differences in preeclampsia in the low PlGF group (21.74% vs 15.91%, p=0.445).

CONCLUSIONS

Unlike other studies, we found that high rather than low PlGF levels were associated with an increased preeclampsia risk. Low PlGF neither identified women at increased risk of preeclampsia nor women who benefitted from aspirin. Further research is needed to determine whether aspirin is beneficial in women with high PlGF, and whether the paradigm linking low PlGF and preeclampsia needs to be reevaluated.

CONDENSATION

High-risk women with low baseline PlGF, a risk factor for preeclampsia, did not benefit from early initiation of low-dose aspirin.

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.

Cerebral autoregulation in different hypertensive disorders of pregnancy

OBJECTIVE

Cerebrovascular complications that are associated with hypertensive disorders of pregnancy (preeclampsia, chronic hypertension [CHTN], and gestational hypertension [GHTN]) are believed to be associated with impaired cerebral autoregulation, which is a physiologic process that maintains blood flow at an appropriate level despite changes in blood pressure. The nature of autoregulation dysfunction in these conditions is unclear. We therefore evaluated autoregulation in 30 patients with preeclampsia, 30 patients with CHTN, and 20 patients with GHTN and compared them with a control group of 30 normal pregnant women.

STUDY DESIGN

The autoregulatory index (ARI) was calculated with the use of simultaneously recorded cerebral blood flow velocity in the middle cerebral artery (transcranial Doppler ultrasound), blood pressure (noninvasive arterial volume clamping), and end-tidal carbon dioxide during a 7-minute period of rest. ARI values of 0 and 9 indicate absent and perfect autoregulation, respectively. We use analysis of variance with Bonferroni test vs a control group. Data are presented as mean ± standard deviation.

RESULTS

ARI was significantly reduced in preeclampsia (ARI, 5.5 ± 1.6; P = .002) and CHTN (ARI, 5.6 ± 1.7; P = .004), but not in GHTN (ARI, 6.7 ± 0.8; P = 1.0) when compared with control subjects (ARI, 6.7 ± 0.8). ARI was more decreased in patients with CHTN who subsequently experienced preeclampsia than in those who did not (ARI, 3.9 ± 1.9 vs 6.1 ± 1.2; P = .001). This was not true for women with GHTN or control subjects who later experienced preeclampsia.

CONCLUSION

Pregnant women with CHTN or preeclampsia (even after exclusion of superimposed preeclampsia) have impaired autoregulation when compared with women with GHTN or normal pregnancy. Whether the decreased ARI in patients with CHTN who later experience preeclampsia is due to preexistent differences or early affected cerebral circulation remains to be determined.

Preeclampsia in high risk women is characterized by risk group-specific abnormalities in serum biomarkers

OBJECTIVE

To determine if early pregnancy serum biomarkers in high-risk women who develop preeclampsia vary according to risk factor.

STUDY DESIGN

We performed a secondary analysis of the Maternal-Fetal Medicine Units Network randomized controlled trial of low-dose aspirin for the prevention of preeclampsia in high-risk women. Serum biomarker levels at enrollment (before initiation of aspirin or placebo) were compared between women who did and did not develop preeclampsia, both for the group as a whole and within each of 4 high-risk groups (insulin-dependent diabetes, hypertension, multiple gestation, and previous preeclampsia) using a regression model adjusting for gestational age at collection and prepregnancy body mass index.

RESULTS

1258 women were included (233 with insulin-dependent diabetes, 387 with chronic hypertension, 315 with a multiple gestation, 323 with previous preeclampsia). Multiple early pregnancy serum biomarkers differed between women who did and did not develop preeclampsia. Each high-risk group had a unique and largely nonoverlapping pattern of biomarker abnormality. Differences between those who did and did not develop preeclampsia were noted in vascular cell adhesion molecule in the diabetes group; human chorionic gonadotropin, soluble tumor necrosis factor receptor-2, tumor necrosis factor-alpha, selectin and angiogenin in the chronic hypertension group; interleukin-6, placental growth factor, soluble fms-like tyrosine kinase plus endoglin to placental growth factor ratio in the multiple gestation group; and angiogenin in the previous preeclampsia group.

CONCLUSION

Patterns of serum biomarkers vary by high-risk group. These data support the hypothesis that multiple pathogenic pathways lead to the disease recognized clinically as preeclampsia.

Predictive value of ophthalmic artery Doppler velocimetry in relation to development of pre-eclampsia

OBJECTIVE

To test the hypothesis that ophthalmic artery Doppler velocimetry is predictive of the development of pre-eclampsia (PE).

METHODS

This was a prospective cohort study that included pregnant women in the second trimester who had risk factors for PE. Seven ophthalmic artery Doppler parameters, in addition to uterine artery (UtA) Doppler and clinical variables, were investigated for their prognostic value with respect to PE.

RESULTS

A total of 347 women were recruited, of whom 40 developed PE. A comparison of the mean ophthalmic artery Doppler parameter values between women with and those without PE showed statistically significant differences in several parameters: peak systolic velocity, end-diastolic velocity, mean velocity, peak mesodiastolic velocity (PMDV) and peak ratio. After adjusting for confounding variables, only PMDV remained statistically significant (P < 0.001), with an area under the receiver-operating characteristics curve (AUC) of 0.73. The best cut-off for predicting PE was a PMDV of > 22.11 cm/s, with sensitivity of 70%, specificity of 75%, positive likelihood ratio of 2.8, negative likelihood ratio of 0.4, positive predictive value of 28% and negative predictive value of 95%. The AUC increased from 0.72 to 0.78 when the PMDV was incorporated into a prediction model based on clinical variables, demonstrating that this marker increased the discriminatory capability of the model. The performance of ophthalmic artery Doppler was similar to that of UtA Doppler for predicting PE. Additionally, the AUC increased significantly from 0.82 to 0.88 when the PMDV was incorporated into the model containing clinical variables and UtA Doppler indices.

CONCLUSION

A high ophthalmic artery PMDV in the second trimester of pregnancy is an independent predictor of PE that increases the discriminatory ability of clinical markers, as well as of models that include clinical variables and UtA Doppler indices.

Multicenter prospective clinical study to evaluate the prediction of short-term outcome in pregnant women with suspected preeclampsia (PROGNOSIS): study protocol

BACKGROUND

Preeclampsia is defined as new onset of hypertension and proteinuria at gestational week 20 or after. However, use of these measures to predict preeclampsia before its clinical onset is unreliable, and evidence suggests that preeclampsia, eclampsia, or hemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome may develop without hypertension or proteinuria being evident. Because of its unpredictability, varying clinical presentation and potential adverse outcomes, pregnant women with suspected preeclampsia require intensive monitoring or hospitalization. Beyond preeclampsia diagnosis, there is a high unmet medical need for more reliable predictive markers for preeclampsia to improve maternal and fetal outcomes and reduce unnecessary hospital admissions. An imbalance of circulating angiogenic and antiangiogenic factors, including raised soluble fms-like tyrosine kinase-1 (sFlt-1) and decreased placental growth factor (PlGF), has been found in women diagnosed with preeclampsia and before clinical onset of the disease. The PRediction of short-term Outcome in preGNant wOmen with Suspected preeclampsIa Study (PROGNOSIS) was designed to investigate the use of the sFlt-1/PlGF ratio in the short-term prediction of preeclampsia.

METHODS/DESIGN

This global, multicenter, prospective, double-blind, non-interventional study aims to derive and validate cutoffs for the sFlt-1/PlGF ratio, to rule out (for 1 week) or rule in (within 4 weeks) the occurrence of preeclampsia/eclampsia/HELLP syndrome. Eligible participants are women presenting at 24 to <37 weeks' gestation with clinical suspicion of, but not manifest preeclampsia/eclampsia/HELLP syndrome. Clinical assessments, maternal serum sFlt-1/PlGF sampling and documentation of maternal/neonatal outcomes are performed at regular intervals, using strict diagnostic criteria for preeclampsia-related conditions and outcomes. Serum sFlt-1 and PlGF analysis will be performed using fully automated Elecsys® immunoassays. Investigators and participants will remain blinded to the results. Target recruitment is 1000 participants. Health economic analysis is also planned.

DISCUSSION

The results of PROGNOSIS will provide the most comprehensive evidence to date on the accuracy of the sFlt-1/PlGF ratio for short-term prediction of preeclampsia/eclampsia/HELLP syndrome. Adoption of the sFlt-1/PlGF test in clinical practice has the potential to reduce the frequency of adverse pregnancy outcomes for both mother and fetus, and decrease healthcare costs associated with unnecessary hospitalization of women with suspected preeclampsia.

Pre-eclampsia part 1: current understanding of its pathophysiology

Pre-eclampsia is characterized by new-onset hypertension and proteinuria at ≥20 weeks of gestation. In the absence of proteinuria, hypertension together with evidence of systemic disease (such as thrombocytopenia or elevated levels of liver transaminases) is required for diagnosis. This multisystemic disorder targets several organs, including the kidneys, liver and brain, and is a leading cause of maternal and perinatal morbidity and mortality. Glomeruloendotheliosis is considered to be a characteristic lesion of pre-eclampsia, but can also occur in healthy pregnant women. The placenta has an essential role in development of this disorder. Pathogenetic mechanisms implicated in pre-eclampsia include defective deep placentation, oxidative and endoplasmic reticulum stress, autoantibodies to type-1 angiotensin II receptor, platelet and thrombin activation, intravascular inflammation, endothelial dysfunction and the presence of an antiangiogenic state, among which an imbalance of angiogenesis has emerged as one of the most important factors. However, this imbalance is not specific to pre-eclampsia, as it also occurs in intrauterine growth restriction, fetal death, spontaneous preterm labour and maternal floor infarction (massive perivillous fibrin deposition). The severity and timing of the angiogenic imbalance, together with maternal susceptibility, might determine the clinical presentation of pre-eclampsia. This Review discusses the diagnosis, classification, clinical manifestations and putative pathogenetic mechanisms of pre-eclampsia.

Predictive biomarkers of pre-eclampsia and effectiveness of preventative interventions for the disease

INTRODUCTION

Pre-eclampsia (PE) is one of the most common pregnancy complication characterized by placental and maternal vascular dysfunction. It affects about 3 - 8% of women during the second half of pregnancy and represents one of the major causes of neonatal morbidity and mortality. The etiology of PE largely remains unknown.

AREAS COVERED

PE is considered a syndrome with multisystem involvement, so the ideal predictive test for it should utilize a combination of many predictors. Measurement in early pregnancy of a variety of biophysical and biochemical markers implicated in the pathophysiology of PE associated with clinical risk factors has been proposed to predict the development of the syndrome, thereby mitigating an adverse outcome.

EXPERT OPINION

The identification of reliable indicators is a clinically relevant issue that could result in early therapeutic intervention and leading to the prevention of maternal and fetal injuries before the manifestation of clinical signs. Many factors complicate the prevention of PE cases. Most are attributed to unknown etiology, the low predictive value of current screening tests and the several presentations of the disease. Although preventative treatments have been studied extensively, an effective intervention to avoid the development of PE has not yet been discovered.