A prospective cohort study of the value of maternal plasma concentrations of angiogenic and anti-angiogenic factors in early pregnancy and midtrimester in the identification of patients destined to develop preeclampsia

Evidence of an imbalance of angiogenic/antiangiogenic factors in massive perivillous fibrin deposition (maternal floor infarction): a placental lesion associated with recurrent miscarriage and fetal death

OBJECTIVE

Massive perivillous fibrin deposition (MPFD) is associated with serious complications of pregnancy including recurrent spontaneous abortion, fetal growth restriction, and fetal demise. The aim of this study was to determine whether maternal plasma concentrations of angiogenic/antiangiogenic factors in MPFD differ from those of uncomplicated pregnancies.

STUDY DESIGN

This retrospective longitudinal case-control study included MPFD cases (n = 10) and control patients (n = 175) with uncomplicated pregnancies who were enrolled in a longitudinal study and delivered at term. Serial plasma concentrations of placental growth factor (PlGF), soluble endoglin (sEng), and soluble vascular endothelial growth factor receptor (sVEGFR)-1 and -2 were determined by an enzyme-linked immunosorbent assay (cases, n = 28 samples; controls, n = 723 samples). Individual analyte concentrations were averaged across gestational age at specimen collection intervals. Linear mixed models were used to test for differences in log-transformed mean analyte concentrations both overall and as a function of time.

RESULTS

The following results were found: (1) patients with MPFD had a lower mean plasma PlGF concentration (P = .03) and higher mean plasma concentrations of sVEGFR-1 and sEng (both P < .01) than controls, adjusted for potential confounders; (2) the mean plasma concentration of PlGF differed further among cases and controls as a function of gestational age interval (P < .0001); however, mean sVEGFR-1 and sEng group differences as a function of gestational age interval approached but did not reach significance (P = .09 and P = .11, respectively); (3) patients with MPFD had lower mean plasma concentrations of PlGF/sVEGFR-1 (P < .0001) and PlGF/sEng (P < .001): both of these relationships differed further as a function of gestational age interval (both P < .0001); and (4) differences in mean sVEGFR-1, sEng, and the ratios of PlGF to sVEGFR-1 and PlGF to sEng were observed before 20 weeks of gestation.

CONCLUSION

An imbalance of angiogenic/antiangiogenic factors is present in patients with MPFD prior to the diagnosis. We propose that these changes participate in the mechanisms responsible for adverse pregnancy outcomes in patients with MPFD.

Circulating levels of neutrophil gelatinase-associated lipocalin (NGAL) correlate with the presence and severity of preeclampsia

OBJECTIVE

Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a reliable marker of acute renal injury and is produced at the maternal-fetal interface but its role in preeclampsia has not been systematically examined. This study investigated whether plasma NGAL concentrations changed in patients with preeclampsia at diagnosis compared to normotensive controls.

STUDY DESIGN

A case-control study was performed. Plasma was collected from women with preeclampsia and normotensive controls matched for age, gestational age, and body mass index. Plasma NGAL concentrations were measured by specific enzyme-linked immunosorbent assay.

RESULTS

Patients with preeclampsia had significantly higher NGAL concentrations than controls (median [range]: 203.8 ng/mL [66.1-575.4] vs. 122.8 ng/mL [7.0-669.7]; P = .047). In subgroup analysis, patients with severe preeclampsia had significantly higher NGAL concentrations than those with mild preeclampsia. Plasma NGAL concentrations were positively correlated with the amount of proteinuria in women with preeclampsia (P = .003).

CONCLUSIONS

Plasma NGAL concentrations were significantly elevated in women with preeclampsia versus normotensive controls, and concentrations appear to be associated with the severity of the disease.

Preeclampsia is associated with an elevation of plasma sMet concentrations in the second trimester

OBJECTIVE

The aim of this study was to investigate the association between anti-angiogenic factor soluble c-Met (sMet) concentrations in maternal plasma and the risk of preeclampsia.

METHODS

The pregnant women included in this study (1) had subsequent preeclampsia (n = 52) and were compared to normal controls (n = 104) at the time of amniocentesis (15-20 weeks); and (2) had preeclampsia (n = 63) and were compared to normal controls (n = 112) at the time of diagnosis of preeclampsia (29-40 weeks). sMet concentrations were measured by ELISA. Non-parametric statistics were used for analysis.

RESULTS

Maternal plasma sMet concentrations were significantly higher in both women with subsequent preeclampsia (median: 1372.7 ng/ml versus 1100.5 ng/ml; p = 0.036) and women with preeclampsia (median: 1651.9 ng/ml versus 1364.7 ng/ml; p < 0.001) than in the controls. After adjusting for potential confounding factors, the risks of developing preeclampsia were as follows: adjusted odds ratio 2.5 (95% confidence interval, 1.2-5.2; p = 0.016) for second trimester sMet concentration with a cut-off value of 1223.5 ng/ml and 4.4 (95% confidence interval, 2.2-9.1; p < 0.001) for third trimester sMet concentration with a cut-off value of 1460.3 ng/ml.

CONCLUSION

Elevated maternal plasma sMet concentrations were independently associated with the increased risk of preeclampsia.

Placental growth factor (PlGF): a key to optimizing fetal growth

The needs of the uterus and the fetus for the provision of nutrients and oxygen, supplied by the blood flow, are understandably extremely high, with the circulatory system playing the most important role in this action. Abnormal vascular growth and transformation that create a high vessel resistance network have been associated with various pregnancy pathologies, including miscarriage, small for gestational age (SGA) fetuses with or without preeclampsia and intrauterine growth restriction (IUGR). Placental growth factor (PlGF) has a major role in vasculogenesis and angiogenesis in human placenta. Low concentrations of PlGF and high concentrations of its inhibitor-soluble Fms-like tyrosine kinase-1 (sFlt-1) are linked with impaired angiogenesis and placental development, leading to the above pregnancy complications. The activity of vascular endothelial growth factor (VEGF), which is the most potent of all angiogenic mediators, is partly modulated by PlGF. Although the mechanisms via which PlGF exerts its various effects are still under investigation, we herein discuss the known actions exerted by this major mediator together with its results on fetal growth.

Serum placental growth factor as a predictor of early onset preeclampsia in overweight/obese pregnant women

The purpose of this study was to analyze whether maternal serum placental growth factor (PlGF) could predict early onset preeclampsia (<32 weeks of gestation) in overweight/obese pregnant women, and whether it could do it more effectively than in normal/underweight pregnant women. A prospective cohort study was conducted on 1678 pregnant women with singleton pregnancies, who were grouped as underweight, normal, overweight, and obese on the basis of body mass index, followed by serum PlGF estimation at 20 to 22 weeks of gestation. A cut-off value of <144 pg/mL for PlGF was determined by Receiver Operating Characteristic curve analysis to identify risk of early onset preeclampsia. Univariate logistic regression analysis revealed significantly stronger association between PlGF <144 pg/mL and early onset preeclampsia in overweight/obese pregnant women (odds ratio 7.64; 95% confidence interval 5.34-10.12; P = .000) than in normal/underweight pregnant women (odds ratio 2.95; 95% confidence interval 1.74-4.26; P = .007). Weight and PlGF levels in study women had a significant negative correlation (r = 0.663; P = .002). Serum PlGF in early second trimester could be an effective predictor of early onset preeclampsia in overweight/obese pregnant women and may be more effective than in normal/underweight pregnant women.

Evaluation of a rapid and simple placental growth factor test in hypertensive disorders of pregnancy

The aim of this study was to investigate the diagnostic accuracy of the Triage placental growth factor (PlGF) assay, together with its prognostic efficiency in determining the need for preterm delivery in all forms of hypertensive disorders of pregnancy. A total of 130 pregnant women with a diagnosis of preeclampsia (PE: 23), HELLP syndrome (20), superimposed preeclampsia (SIPE: 17), chronic hypertension (CHT: 25), gestational hypertension (GHT: 18) and 27 normotensive pregnant controls were enrolled in this case-control study. A single blood sample was taken between 22 and 34 weeks of gestation, and the plasma was analyzed for PlGF using the Alere Triage PlGF assay. The PlGF levels found in all hypertensive disorder groups differed significantly from those observed in controls. There was a highly significant difference in PlGF concentrations between women with a pregnancy duration <35 weeks and controls. Using a gestational age-dependent threshold of 5% of normal, a positive PlGF test predicted delivery before 35 weeks in 93.7% of hypertensive women and delivery before 37 weeks in 90.5% of hypertensive women. A positive PlGF test identified the following proportions of hypertensive patients: 95.7% (PE), 95.0% (HELLP syndrome), 82.4% (SIPE), 60.0% (CHT) and 44.4% (GHT). A positive PlGF test was associated with a significantly shorter duration of pregnancy (hazard ratio of 3.43 adjusted for the gestational age at the time of sample collection and hypertension with proteinuria). In conclusion, PlGF concentrations are significantly lower in all hypertensive disorders. A positive test using the Triage PlGF assay at 22-34 weeks of gestation predicts delivery before 37 weeks in women with both proteinuric and non-proteinuric hypertensive disorders of pregnancy.

Endoglin in amniotic fluid as a risk factor for the subsequent development of bronchopulmonary dysplasia

OBJECTIVE

Cross-talk between inflammation and angiogenesis pathways has been recently reported. The objectives of this study were to: (i) examine whether amniotic fluid (AF) concentrations of soluble endoglin (sEng), a protein with anti-angiogenic properties, change during pregnancy, parturition, or intra-amniotic infection and/or inflammation (IAI); (ii) determine whether an increase in sEng in the AF of patients with preterm labor (PTL) and preterm prelabor rupture of membranes (PROM) is associated with adverse neonatal outcomes; and (iii) investigate potential sources of sEng in AF.

STUDY DESIGN

A cross-sectional study was conducted to include patients in the following groups: (i) mid-trimester (n = 20); (ii) PTL with term delivery (n = 95); (iii) PTL leading to preterm delivery with (n = 40) and without IAI (n = 46); (iv) preterm PROM with (n = 37) and without IAI (n = 37); (v) term in labor (n = 48) and not in labor (n = 44). AF concentrations of sEng were determined by enzyme-linked immunosorbent assay. Chorioamniotic membranes, umbilical cord blood, and AF macrophages were examined for the expression of endoglin.

RESULTS

(i) Patients with IAI had a higher median AF concentration of sEng than those without IAI (P = 0.02 for PTL and 0.06 for preterm PROM); (ii) AF concentrations of sEng in the 3rd and 4th quartiles were associated with IAI (OR 2.5 and 7.9, respectively); (iii) an AF sEng concentration ≥779.5 pg/mL was associated with bronchopulmonary dysplasia (BPD) (OR 7.9); (iv) endoglin was co-localized with CD14+ macrophages in AF pellets of patients with IAI by immunofluorescence and flow cytometry; and (v) the concentration of sEng in the supernatant was significantly increased after the treatment of macrophages with endotoxin or TNF-α.

CONCLUSIONS

Soluble endoglin participates in the host response against IAI. Activated macrophages may be a source of sEng concentrations in the AF of patients with IAI. An increase of sEng in the AF is associated with BPD and adverse neonatal outcomes.

Placental growth factor for the prediction of adverse outcomes in patients with suspected preeclampsia or intrauterine growth restriction

Background

The circulating concentration of PlGF is reported to be lower in patients experiencing preeclampsia and patients delivering a small for gestational age (SGA) neonate. To evaluate the predictive value of circulating PlGF for preeclampsia and adverse outcome in patients with suspected preeclampsia or intrauterine growth restriction (IUGR).

Methodology/Principal Findings

A double blind prospective study. We enrolled 96 women for suspected preeclampsia or IUGR, and measured plasma levels of PlGF (Triage®) at enrolment. We defined adverse outcome as severe preeclampsia, SGA neonate (<10^th centile) or elective delivery for maternal or fetal complication. Severe adverse outcome was studied among patients included <34 weeks gestation (WG) and defined as eclampsia, HELLP syndrome, very SGA (<3^rd centile) or elective delivery <34 WG. The mean logtransformed PlGF level was lower for women who experienced preeclampsia (2.9 vs 3.7, p = 0.02), and was markedly lower for patients who experienced adverse outcome (2.9 vs 4.3, p<0.001). The odds of presenting an adverse outcome were higher for the lowest tertile of PlGF compared to the higher (OR = 13 , 95% CI [3–50]). For severe adverse outcome, odds were respectively for the lowest and intermediate tertile as compared with the higher tertile : OR = 216, 95% CI [18–2571]; and OR = 17, 95% CI [3–94]. When included <34 WG, patients with a PlGF level <12 pg/ml experienced a severe adverse outcome in 96% of cases (24/25), and only 1 of 20 patients with a PlGF level >5^th centile experienced a severe adverse outcome within 15 days (5%).

Conclusions/Significance

Among women with suspected preeclampsia or IUGR, PlGF helps identify women who will experience an adverse outcome and those who will not within a time period of 15 days.

Plasma concentrations of soluble endoglin versus standard evaluation in patients with suspected preeclampsia

Background

The purpose of this study was to compare plasma soluble endoglin (sEng) levels with standard clinical evaluation or plasma levels of other angiogenic proteins [soluble fms-like tyrosine kinase 1 (sFlt1) and placental growth factor (PlGF)] in predicting short-term adverse maternal and perinatal outcomes in women with suspected preeclampsia presenting prior to 34 weeks.

Methods and Findings

Data from all women presenting at <34 weeks for evaluation of preeclampsia with singleton pregnancies (July 2009−October 2010) were included in this analysis and sEng levels were measured at presentation. Data was analyzed for 170 triage encounters and presented as median {25−75^th centile}. Thirty-three percent of patients (56 of 170) experienced an adverse outcome. sEng levels (ng/ml) were significantly elevated in patients who subsequently experienced adverse outcomes compared to those who did not (32.3 {18.1, 55.8} vs 4.8 {3.2, 8.6}, p<0.0001). At a 10% false positive rate, sEng had higher detection rates of adverse outcomes than the combination of highest systolic blood pressure, proteinuria and abnormal laboratory tests (80.4 {70.0, 90.8} vs 63.8 {51.4, 76.2}, respectively). Subjects in the highest quartile of sEng were more likely to deliver early compared to those in the lowest quartile (HR: 14.96 95% CI: 8.73−25.62, p<0.0001). Natural log transformed sEng correlated positively with log sFlt1 levels (r = 0.87) and inversely with log PlGF levels (r = −0.79) (p<0.0001 for both). Plasma sEng had comparable area under the curve for prediction of adverse outcomes as measurement of sFlt1/PlGF ratio (0.88 {0.81, 0.95} for sEng versus 0.89 {0.83, 0.95} for sFlt1/PlGF ratio, p = 0.74).

Conclusions

In women with suspected preeclampsia presenting prior to 34 weeks of gestation, sEng performs better than standard clinical evaluation in detecting adverse maternal and fetal outcomes occurring within two weeks of presentation. Soluble endoglin was strongly correlated with sFlt1 and PlGF levels, suggesting common pathogenic pathways leading to preeclampsia.

Perfusion with magnesium sulfate increases sFlt-1 secretion only in the fetal side of placenta of women with preeclampsia

OBJECTIVE

To examine the effect of magnesium sulfate (MgSO(4)) on sFlt (soluble fms-like tyrosine kinase)-1 in the fetal and maternal compartments of normotensive and preeclamptic placentas.

METHODS

Cotyledons of term normotensive and preeclamptic placentas were dually perfused for six hours, with control medium and MgSO(4) (6-7 mg %) in the maternal reservoir. Perfusate sFlt-1 concentrations were measured.

RESULTS

Median sFlt-1 concentration was higher in the maternal than in the fetal side in both groups and perfusion media (p < 0.0001). When perfused with control medium, the maternal side median sFlt-1 concentration was higher in the preeclampsia than in the control group (p < 0.0001). After perfusion with MgSO(4), the median maternal and fetal sides perfusate sFlt-1 concentration were higher in the preeclampsia than in the control group (p < 0.0001). In comparison to perfusion with control medium, the median sFlt-1 concentration of normal pregnant women decreased in the fetal and increased in the maternal side. In the preeclampsia group, only median fetal side sFlt-1 concentration increased.

CONCLUSION

In contrast to normal pregnant women, perfusion with MgSO(4) of preeclamptic placentas did not increase their sFlt-1 concentration. This may indicate that MgSO(4) role may be limited to its anti-eclamptic and does not affect the anti-angiogenic state associated with preeclampsia.

Angiogenic and fibrinolytic factors in blood during the first half of pregnancy and adverse pregnancy outcomes

OBJECTIVE

To estimate whether the imbalance of angiogenic factors (soluble fms-like tyrosine kinase-1, placental growth factor) and fibrinolytic factors (plasminogen activator inhibitor-2 [PAI-2]) might affect placentation in early pregnancy.

METHODS

We studied the associations of maternal soluble fms-like tyrosine kinase-1, placental growth factor, and PAI-2 concentrations in the first trimester (before 18 weeks of gestation) and soluble fms-like tyrosine kinase-1 and placental growth factor concentrations in the second trimester (18-25 weeks of gestation) with placental function and adverse pregnancy outcomes. This study was embedded in a population-based prospective cohort study. Data were used from 7,519 women. Biomarker concentrations were divided into deciles and evaluated in multivariable linear and logistic regression models.

RESULTS

First-trimester high soluble fms-like tyrosine kinase-1 was associated with a 5.2% lower uterine artery index in the second-trimester and a 1.6% higher birth weight (55 g, confidence interval [CI] 15-95). Neither in the first nor in the second trimester were soluble fms-like tyrosine kinase-1 concentrations significantly associated with preeclampsia. First-trimester low placental growth factor was associated with a 6.1% higher uterine artery index and a 3.4% lower birth weight (-115 g, CI -157 to -74). First-trimester low placental growth factor was associated with fetal growth restriction (odds ratio [OR] 2.62, CI 1.68-4.08) and preeclampsia (OR 2.46, CI 1.49-4.08). First-trimester low PAI-2 was associated with a 1.9% higher uterine artery index and a 2.7% lower birth weight (-94 g, CI -136 to -51). First-trimester low PAI-2 was associated with a higher risk of fetal growth restriction (OR 2.22, CI 1.39-3.55).

CONCLUSION

First-half-of-pregnancy concentrations of soluble fms-like tyrosine kinase-1, placental growth factor, and PAI-2 are associated with uteroplacental vascular resistance, placental weight, and birth weight. Moreover, first-trimester placental growth factor and PAI-2 are associated with an increased risk of adverse pregnancy outcomes.

LEVEL OF EVIDENCE

II.

Examining the correlation between placental and serum placenta growth factor in preeclampsia

OBJECTIVE

Decreased levels of serum placenta growth factor (PlGF) are associated with preeclampsia. We sought to determine whether serum and placental levels of PlGF (sPlGF and pPlGF) are associated with preeclampsia and whether there is a correlation between serum and placental PlGF levels.

STUDY DESIGN

These analyses were part of a larger, prospective, case-control study. Cases were women with preeclampsia. Controls were women without preeclampsia who delivered at term. Analyses included nonparametric tests to compare medians, logistic regression to estimate odds, and calculation of correlation coefficients.

RESULTS

Twenty-four cases (10 preterm, 14 term) were compared with 14 controls. Median levels of PlGF were significantly lower in cases than controls (pPlGF: 232.6 vs 363.4 pg/mL, P = .02; sPlGF: 85.5 vs 274.4 pg/mL, P < .001). Serum and placental PlGF were correlated (overall: 39%, P = .006; cases with preterm preeclampsia and growth restriction: 87%, P = .02).

CONCLUSION

Serum and placental PlGF are independently associated with preeclampsia and correlated with each other.

Timing of ischemic insult alters fetal growth trajectory, maternal angiogenic balance, and markers of renal oxidative stress in the pregnant rat

Increased uterine artery resistance and angiogenic imbalance characterized by increased soluble fms-like tyrosine kinase-1 (sFlt-1) and decreased free vascular endothelial growth factor (VEGF) are often associated with placental insufficiency and preeclampsia but not synonymous with hypertension. We hypothesized chronic reductions in utero-placental perfusion (RUPP) for 5 days (d) during either mid- (d12-d17) or late (d14-d19) gestation would have disparate effects on plasma sFlt-1 and VEGF levels and blood pressure. Five days of chronic RUPP was achieved by placement of silver clips on the abdominal aorta and ovarian arteries on either gestational d12 or d14. Arterial pressure was increased (P < 0.05) in RUPP vs. normal pregnant (NP) in both d17 (10%) and d19 (25%) groups, respectively. Circulating free VEGF was decreased (P < 0.05) and sFlt-1:VEGF ratio increased (P < 0.05) after 5 days of RUPP ending on d19 but not d17 compared with NP controls. Angiogenic imbalance, measured by an endothelial tube formation assay, was present in the d19 RUPP but not the d17 RUPP compared with age-matched NP rats. Five days of RUPP from days 14 to 19 decreased fetal and placental weights 10% (P < 0.01) compared with d19 NP controls. After 5 days of RUPP, from days 12 to 17 of pregnancy, fetal weights were 21% lighter (P < 0.01) compared with d17 NP controls, but placental weight was unchanged. These findings suggest that the timing during which placental insufficiency occurs may play an important role in determining the extent of alterations in angiogenic balance, fetal growth restriction, and the severity of placental ischemia-induced hypertension.

Early detection of maternal risk for preeclampsia

Preeclampsia is one of the leading causes of maternal and fetal morbidity and mortality. New molecular insights offer new possibilities of early diagnosis of elevated maternal risk. Maternal risk factors, biophysical parameters like Doppler examination of the uterine arteries and biochemical parameters allow early risk calculation. Preventive and effective therapeutic agents like acetylsalicylacid can be started in the early second trimester. This article reviews the diagnostic possibilities of early risk calculation to detect women having high risk for preeclampsia and the potential benefits for them, the offspring and health care systems. We provide risk calculation for preeclampsia as an important and sensible part of first trimester screening.

Circulating angiogenic factors and risk of adverse maternal and perinatal outcomes in twin pregnancies with suspected preeclampsia

To evaluate whether angiogenic factor levels correlate with preeclampsia-related adverse maternal and perinatal outcomes in women with twin pregnancy, we studied 79 women with suspected preeclampsia in the 3rd trimester. Antiangiogenic soluble fms-like tyrosine kinase-1 (sFlt-1) and proangiogenic placental growth factor (PlGF) were measured at presentation on an automated platform. An adverse outcome was defined as hemolysis, elevated liver enzymes, and low platelets syndrome; disseminated intravascular coagulation; abruption; pulmonary edema; cerebral hemorrhage; maternal, fetal, and neonatal death; eclampsia; acute renal failure; small for gestational age; and indicated delivery. All outcomes were ascertained 2 weeks after initial evaluation. Comparing the 52 women (65.8%) who experienced an adverse outcome with the 27 women (34.2%) without an adverse outcome, the median sFlt-1 was elevated (11461.5 pg/mL [8794.0-14847.5] versus 7495.0 pg/mL [3498.0-10482.0; P=0.0004]), PlGF was reduced (162.5 pg/mL [98.0-226.5] versus 224.0 pg/mL [156.0-449.0]; P=0.005), and sFlt-1/PlGF ratio was elevated (74.2 [43.5-110.5] versus 36.2 [7.1-71.3]; P=0.0005). Among those presenting <34 weeks (n=40), the difference in sFlt-1/PlGF ratio was more striking (97.7 [76.6-178.1] versus 31.7 [6.5-48.7]; P=0.001). Addition of sFlt-1/PlGF to the highest systolic blood pressure and proteinuria improved prediction of adverse outcomes. We conclude that in women with twin pregnancy and suspected preeclampsia, the sFlt-1/PlGF ratio at the time of initial evaluation is associated with subsequent adverse maternal and perinatal outcomes. These findings are similar to those in singleton pregnancies and may implicate common pathogenic pathways.

Angiogenic imbalance and plasma lipid alterations in women with preeclampsia from a developing country

BACKGROUND

An imbalance between anti-angiogenic factors (e.g. soluble vascular endothelial growth factor receptor-1 (s-FLT1) and soluble endoglin (s-Eng)) and pro-angiogenic factors (e.g. placental growth factor (PlGF)) as well as increased oxidized low-density lipoprotein (ox-LDL) concentrations have been associated with preeclampsia (PE). Risk factors associated with the development of PE, however, are known to be different between developed and developing countries. The aim of the study was to determine the levels of s-FLT1, s-Eng, PIGF, and ox-LDL in women with PE from a developing country.

METHODS

A multi-center case-control study was conducted. One hundred and forty three women with PE were matched by age and parity with 143 healthy pregnant women without cardiovascular or endocrine diseases. Before delivery, blood samples were taken and serum was stored until analysis.

RESULTS

Women with PE had lower concentrations of PIGF (p<0.0001) and higher concentrations of s-Eng (p=0.001) than healthy pregnant women. There were no differences between the groups regarding ox-LDL or s-FLT1. Women with early onset PE had higher s-FLT1 concentrations (p=0.0004) and lower PIGF concentrations (p<0.0001) than their healthy pregnant controls. Women with late onset PE had higher concentrations of s-Eng (p=0.005). Women with severe PE had higher concentrations of s-Eng (p=0.0008) and ox-LDL (p=0.01), and lower concentrations of PIGF (p<0.0001).

CONCLUSIONS

Women with PE from a developing country demonstrated an angiogenic imbalance and an increased rate of LDL oxidation. Findings from this study support the theory that PE is a multifactorial disease, and understanding differences in these subpopulations may provide a better target to approach future therapies.

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

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

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

The vascular endothelial growth factor family in adverse pregnancy outcomes

BACKGROUND

Pre-eclampsia, small-for-gestational-age infants, preterm birth and recurrent miscarriage complicate a significant number of pregnancies. The vascular endothelial growth factor (VEGF) family of angiogenic growth factors is implicated in the pathophysiology of these complications. We aimed to elucidate the role of these angiogenic factors in placentation and to evaluate the predictive value of their protein concentrations and genetic variations in pregnancy complications.

METHODS

We performed a systematic search of PubMed, and retrieved original articles. The search included a combination of terms such as VEGF-A, placental growth factor (PlGF), kinase insert domain receptor, fms-like-tyrosine-kinase receptor 1, soluble fms-like-tyrosine-kinase receptor 1, pre-eclampsia, small-for-gestational-age infants, preterm birth, recurrent miscarriage, placenta, prediction and polymorphisms.

RESULTS

This review summarizes the current knowledge of the roles of the VEGF family in early placentation and of the abnormalities in maternal plasma and placental expression of angiogenic proteins in adverse pregnancy outcomes compared with normal pregnancy. PlGF and sFLT-1 in combination with other clinical and biochemical markers in late first or second trimester appear to predict early-onset pre-eclampsia with a high sensitivity and specificity. However, VEGF family proteins do not have sufficient power to accurately predict late-onset pre-eclampsia, small-for-gestational age pregnancies or preterm birth. Functional polymorphisms in these angiogenic genes are implicated in pregnancy complications, but their contribution appears to be minor.

CONCLUSIONS

Although the VEGF family has important roles in normal and complicated pregnancy, the current predictive value of the VEGF family as biomarkers appears to be limited to early-onset pre-eclampsia.

Second trimester anti-angiogenic proteins and preeclampsia

OBJECTIVE: To measure the relationships between soluble fms-like tyrosine kinase-1 (sFlt1), soluble endoglin (sEng) and preeclampsia. STUDY DESIGN: We utilized a nested case-control study comprised of 211 preeclamptic women and 213 normotensive women with primiparous singleton pregnancies enrolled from ≥13 and <27 gestational weeks among the Danish National Birth Cohort of 100,000 women. Relationships between sFlt1, sEng and preeclampsia were estimated using smoothing splines in generalized linear models, adjusting for maternal age, body mass index, pre-existing hypertension, smoking, and gestational age. MAIN OUTCOME MEASURES: Preeclampsia was confirmed by an International Classification of Diseases (ICD) discharge diagnosis of 637.03, 637.04 637.09, 637.19 (ICD-8) or DO14 to DO15 (ICD-10) in the National Hospital Discharge Registry. In this sample, few cases delivered small for gestational age infants (8.1%) and the mean gestational age at delivery was term (38.2 ± 2.3 weeks). RESULTS: Doublings in the expressions of sFlt1 and sEng were associated with 39% (95% CI = 3%, 86%) and 74% (95% CI = 1%, 198%) increased risks of preeclampsia respectively. CONCLUSIONS: We conclude that second trimester high sFlt1 and sEng levels were possibly associated with an increased risk of preeclampsia after adjustment for maternal factors traditionally associated with the syndrome.

Relationships among maternal nutrient intake and placental biomarkers during the 1st trimester in low-income women

PURPOSE

Pre-eclampsia is a multi-system disorder caused by inadequate placentation in early pregnancy; however, little is known about the influence of nutrient intake on placental development during the crucial 1st trimester. The objective of this study was to examine the relationships between nutrient intake and the raw values and ratios of angiogenic [placental growth factor (PlGF)] and antiangiogenic [soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng)] placental biomarkers in the 1st trimester.

METHODS

A cross-sectional study of low-income, pregnant women (n = 118). Average nutrient intake was calculated from three 24-h dietary recalls. Biomarker values were adjusted for gestational age and nutrients were adjusted for energy.

RESULTS

The angiogenic to antiangiogenic ratio [PlGF/(sFlt-1 × sEng)] was positively related to intake of vitamin D (r = 0.24), vitamin B(2) (r = 0.25), B(12) (r = 0.20), dietary folate equivalents (r = 0.19), iron (r = 0.19), and zinc (r = 0.19) and negatively related to transfats (r = -0.24). Principal component analysis revealed that a vitamin/mineral factor [t (112) = 2.58, p = 0.011] and transfats factor [t (112) = -2.03, p = 0.045] were significant predictors of the PlGF/(sFlt-1 × sEng) ratio. The vitamin and mineral factor was a significant predictor of sFlt-1 [t (122) = 2.29, p = 0.024].

CONCLUSIONS

Expression of placental biomarkers in the early weeks of pregnancy may be influenced by intake of nutrients. Understanding the influence of maternal nutrient intake and placental development in the 1st trimester may provide the opportunity to avert the development or blunt the severity of preeclampsia.

First trimester maternal serum PIGF, free β-hCG, PAPP-A, PP-13, uterine artery Doppler and maternal history for the prediction of preeclampsia

OBJECTIVE

To evaluate the detection of pregnancy hypertensive disorders by integrating maternal history, serum biomarkers and uterine artery Doppler in the first trimester.

METHODS

We prospectively recruited 2118 women that underwent an 11-13 weeks aneuploidy screening. We gathered information on maternal history, uterine artery Doppler and serum biomarkers (PAPP-A, PlGF, PP-13 and free β-hCG). Models were developed for the prediction of overall preeclampsia (PE), early-onset PE, late-onset PE and gestational hypertension (GH). For each outcome, we performed a multivariate logistic regression starting from the saturated model: adopting a step-down procedure we excluded all factors not statistically significant (p > 0.05). Sensitivity models only for statistically significant parameters were calculated from the ROC curves for fixed false-positive rates (FPR).

RESULTS

Among 2118 women, 46 (2.17%) developed GH and 25 (1.18%) were diagnosed with PE, including 12 (0.57%) early-onset PE and 13 (0.61%) late-onset PE. For a fixed FPR of 10 and 5%, serum PlGF, free β-hCG and chronic hypertension identified respectively 67 and 75% of women who developed early-onset PE. In the model for the prediction of overall PE the combination of the uterine artery Doppler pulsatility index (UtA PI) with PlGF and chronic hypertension reached a sensitivity of 60% for a 20% of FPR.

CONCLUSION

An integration of maternal characteristics and first trimester maternal serum biomarkers (free β-hCG and PlGF) provided a possible screening for early-onset PE. In the overall PE model, UtA PI turned out to be statistically significant but did not improve the detection rate.

Accuracy of circulating placental growth factor, vascular endothelial growth factor, soluble fms-like tyrosine kinase 1 and soluble endoglin in the prediction of pre-eclampsia: a systematic review and meta-analysis

BACKGROUND

Biomarkers have been proposed for identification of women at increased risk of developing pre-eclampsia.

OBJECTIVES

To investigate the capacity of circulating placental growth factor (PlGF), vascular endothelial growth factor (VEGF), soluble fms-like tyrosine kinase-1 (sFLT1) and soluble endoglin (sENG) to predict pre-eclampsia.

SEARCH STRATEGY

Medline and Embase through October 2010 and reference lists of reviews, without constraints.

SELECTION CRITERIA

We included original publications on testing of PlGF, VEGF, sFLT1 and sENG in serum or plasma of pregnant women at <30 weeks of gestation and before clinical onset of pre-eclampsia.

DATA COLLECTION AND ANALYSIS

Two reviewers independently identified eligible studies, extracted descriptive and test accuracy data and assessed methodological quality. Summary estimates of discriminatory performance were obtained.

MAIN RESULTS

We included 34 studies. Concentrations of PlGF (27 studies) and VEGF (three studies) were lower in women who developed pre-eclampsia: standardised mean differences (SMD) -0.56 (95% CI -0.77 to -0.35) and -1.25 (95% CI -2.73 to 0.23). Concentrations of sFLT1 (19 studies) and sENG (ten studies) were higher: SMD 0.48 (95% CI 0.21-0.75) and SMD 0.54 (95% CI 0.24-0.84). The summary diagnostic odds ratios were: PlGF 9.0 (95% CI 5.6-14.5), sFLT1 6.6 (95% CI 3.1-13.7), sENG 4.2 (95% CI 2.4-7.2), which correspond to sensitivities of 32%, 26% and 18%, respectively, for a 5% false-positive rate.

AUTHOR'S CONCLUSIONS

PlGF, sFLT1 and sENG showed modest but significantly different concentrations before 30 weeks of gestation in women who developed pre-eclampsia. Test accuracies of all four markers, however, are too poor for accurate prediction of pre-eclampsia in clinical practice.

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

BACKGROUND

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

CONTENT

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

SUMMARY

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

Angiogenic factors in superimposed preeclampsia: a longitudinal study of women with chronic hypertension during pregnancy

Imbalances in circulating angiogenic factors contribute to the pathogenesis of preeclampsia. To characterize levels of angiogenic factors in pregnant women with chronic hypertension, we prospectively followed 109 women and measured soluble fms-like tyrosine kinase 1 (sFlt1), soluble endoglin, and placental growth factor at 12, 20, 28, and 36 weeks' gestation and postpartum. Superimposed preeclampsia developed in 37 (34%) and was early onset (<34 weeks) in 9 and later onset (≥34 weeks) in 28. Circulating levels of sFlt1 and the ratio of sFlt1 to placental growth factor were higher before clinical diagnosis at 20 weeks' gestation in women who subsequently developed early onset preeclampsia between 28 and 34 weeks compared with levels in women who never developed preeclampsia (P=0.001) or who developed late-onset preeclampsia (P=0.001). Circulating levels of sFlt1, soluble endoglin, and the ratio of sFlt1:placental growth factor were also significantly higher, and placental growth factor levels were significantly lower at the time of clinical diagnosis of superimposed preeclampsia in women with either early or late-onset superimposed preeclampsia compared with levels at similar gestational ages in those with uncomplicated chronic hypertension. We conclude that alterations in angiogenic factors are detectable before and at the time of clinical diagnosis of early onset superimposed preeclampsia, whereas alterations were observed only at the time of diagnosis in women with late-onset superimposed preeclampsia. Longitudinal measurements of angiogenic factors may help anticipate early onset superimposed preeclampsia and facilitate diagnosis of superimposed preeclampsia in women with chronic hypertension.

Glycogen phosphorylase isoenzyme BB plasma concentration is elevated in pregnancy and preterm preeclampsia

Glycogen phosphorylase is a key enzyme in glycogenolysis. Released with myocardial ischemia, blood concentration of glycogen phosphorylase isoenzyme BB (GPBB) is a marker of acute coronary syndromes. Pregnancy imposes metabolic stress, and preeclampsia is associated with cardiac complications. However, plasma GPBB concentration during pregnancy is unknown. This study was conducted to determine maternal plasma GPBB concentration in normal pregnancy and in preeclampsia. Plasma samples from 6 groups (n=396) were studied: nonpregnant and pregnant women with normal term delivery, term and preterm preeclampsia, and term and preterm small-for-gestational-age neonates. GPBB concentration was measured with a specific immunoassay. Placental tissues (n=45) obtained from pregnant women with preterm and term preeclampsia, spontaneous preterm delivery, and normal term delivery were analyzed for potential GPBB expression by immunoblotting. Median plasma GPBB concentration was higher in pregnant women than in nonpregnant women (38.7 versus 9.2 ng/mL; P<0.001), which remained significant after adjusting for age, race, and parity. Maternal plasma GPBB concentrations did not change throughout gestation. Cases of preterm (but not term) preeclampsia had higher median plasma GPBB concentrations than gestational age-matched normal pregnancy cases (72.6 versus 26.0 ng/mL; P=0.001). Small-for-gestational-age neonates did not affect plasma GPBB concentration. GPBB was detected in the placenta and was less abundant in preterm preeclampsia than in preterm delivery cases (P<0.01). There is physiological elevation of plasma GPBB concentration during pregnancy; an increase in maternal plasma GPBB is a novel phenotype of preterm preeclampsia. It is strongly suggested that these changes are attributed to GPBB of placental origin.

Angiogenic factors and the risk of adverse outcomes in women with suspected preeclampsia

BACKGROUND

An imbalance in circulating angiogenic factors plays a central role in the pathogenesis of preeclampsia.

METHODS AND RESULTS

We prospectively studied 616 women who were evaluated for suspected preeclampsia. We measured plasma levels of antiangiogenic soluble fms-like tyrosine kinase 1 (sFlt1) and proangiogenic placental growth factor (PlGF) at presentation and examined for an association between the sFlt1/PlGF ratio and subsequent adverse maternal and perinatal outcomes within 2 weeks. The median sFlt1/PlGF ratio at presentation was elevated in participants who experienced any adverse outcome compared with those who did not (47.0 [25th-75th percentile, 15.5-112.2] versus 10.8 [25th-75th percentile, 4.1-28.6]; P<0.0001). Among those presenting at <34 weeks (n=167), the results were more striking (226.6 [25th-75th percentile, 50.4-547.3] versus 4.5 [25th-75th percentile, 2.0-13.5]; P<0.0001), and the risk was markedly elevated when the highest sFlt1/PlGF ratio tertile was compared with the lowest (odds ratio, 47.8; 95% confidence interval, 14.6-156.6). Among participants presenting at <34 weeks, the addition of sFlt1/PlGF ratio to hypertension and proteinuria significantly improved the prediction for subsequent adverse outcomes (area under the curve, 0.93 for hypertension, proteinuria, and sFlt1/PlGF versus 0.84 for hypertension and proteinuria alone; P=0.001). Delivery occurred within 2 weeks of presentation in 86.0% of women with an sFlt1/PlGF ratio ≥85 compared with 15.8% of women with an sFlt1/PlGF ratio <85 (hazard ratio, 15.2; 95% confidence interval, 8.0-28.7).

CONCLUSIONS

In women with suspected preeclampsia presenting at <34 weeks, circulating sFlt1/PlGF ratio predicts adverse outcomes occurring within 2 weeks. The accuracy of this test is substantially better than that of current approaches and may be useful in risk stratification and management. Additional studies are warranted to validate these findings.

The sFlt-1/PlGF ratio in different types of hypertensive pregnancy disorders and its prognostic potential in preeclamptic patients

OBJECTIVE

The soluble fms-like tyrosine kinase (sFlt-1)/placental growth factor (PlGF) ratio is a reliable tool in the assessment of preeclampsia. We tested the hypothesis that the sFlt-1/PlGF ratio is able to identify women at risk for imminent delivery. We characterized the sFlt-1/PlGF ratio in different types of hypertensive pregnancy disorders.

STUDY DESIGN

We investigated 388 singleton pregnancies with normal pregnancy outcome, 164 with PE, 36 with gestational hypertension, and 42 with chronic hypertension. sFlt-1 and PlGF were measured in serum samples.

RESULTS

Patients with preeclampsia had a significantly increased sFlt-1/PlGF ratio as compared with controls and with patients with chronic and gestational hypertension in <34 weeks and ≥34 weeks (P < .001). Time to delivery was significantly reduced in women with preeclampsia in the highest quartile of the sFlt-1/PlGF ratio (P < .001).

CONCLUSION

The sFlt-1/PlGF ratio allows the identification of women at risk for imminent delivery and is a reliable tool to discriminate between different types of pregnancy-related hypertensive disorders.

Angiogenic growth factors in the diagnosis and prediction of pre-eclampsia

The pathogenesis of pre-eclampsia is still not completely known; however, in the recent decade, there have been tremendous research efforts leading to impressive results highlighting the role of a disturbed angiogenic balance as one of the key features of the disease. Numerous studies have shown the key role of the placenta in the pathogenesis of pre-eclampsia. A shift in the sFlt-1 (soluble Fms-like tyrosine kinase-1)/PlGF (placental growth factor) ratio is associated with the disease. Although pre-eclampsia seems to be a clearly defined disease, clinical presentation, and particularly the dynamics of the clinical course, can vary enormously. The only available tools to diagnose pre-eclampsia are blood pressure measurement and urine protein sampling. However, these tools have a low sensitivity and specificity regarding the prediction of the course of the disease or maternal and perinatal outcomes. The only cure for the disease is delivery, although a timely diagnosis helps in decreasing maternal and fetal morbidity and mortality. The sFlt1/PlGF ratio is able to give additional valuable information on the status and progression of the disease and is apt to be implemented in the diagnostic algorithm of pre-eclampsia. In the present review, we aim to provide an overview of the vast literature on angiogenesis and anti-angiogenesis factors in pre-eclampsia that have been published over the last decade. We introduce work from basic research groups who have focused on the pathophysiological basis of the disease. Furthermore, we review studies with a clinical focus in which the sFlt-1/PlGF ratio has been analysed along with other candidates for routine clinical assessment of pre-eclampsia.

Placental lesions associated with maternal underperfusion are more frequent in early-onset than in late-onset preeclampsia

OBJECTIVE

Preeclampsia (PE) has been classified into early- and late-onset disease. These two phenotypic variants of PE have been proposed to have a different pathophysiology. However, the gestational age cut-off to define "early" vs. "late" PE has varied among studies. The objective of this investigation was to determine the prevalence of lesions consistent with maternal underperfusion of the placenta in patients with PE as a function of gestational age.

STUDY DESIGN

A nested case-control study of 8307 singleton pregnant women who deliver after 20 weeks of gestation was constructed based on a cohort. Cases were defined as those with PE (n=910); controls were pregnant women who did not have a hypertensive disorder in pregnancy (n=7397). The frequency of maternal underperfusion of the placenta (according to the criteria of the Society for Pediatric Pathology) was compared between the two groups. Logistic regression was used for analysis. Estimated relative risks (RRs) were calculated from odds ratios.

RESULTS

1) The prevalence of lesions consistent with maternal underperfusion was higher in patients with PE than in the control group [43.3% vs. 15.9%, unadjusted odds ratio 4.0 (95% CI 3.5-4.7); P<0.001]; 2) the estimated RR of maternal underperfusion lesions in PE was higher than in the control group [RR=2.8 (95% CI 2.5-3.0)]; 3) the lower the gestational age at delivery, the higher the RR for these lesions; 4) early-onset PE, regardless of the gestational age used to define it (<32, 33, 34, 35 or 37 weeks) had a significantly higher frequency of placental lesions consistent with maternal underperfusion than late-onset PE (P<0.001 for all).

CONCLUSIONS

1) The earlier the gestational age of preeclampsia at delivery, the higher the frequency of placental lesions consistent with maternal underperfusion; 2) our data suggest that demonstrable placental involvement as determined by pathologic examination differs in early- and late-onset preeclampsia; and 3) this phenomenon appears to be a continuum, and we could not identify a clear and unambiguous gestational age at which lesions consistent with underperfusion would not be present.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

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

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

Angiogenic factors and preeclampsia

Preeclampsia, a hypertensive disorder peculiar to pregnancy, is a systemic syndrome that appears to originate in the placenta and is characterized by widespread maternal endothelial dysfunction. Until recently, the molecular pathogenesis of phenotypic preeclampsia was largely unknown, but recent observations support the hypothesis that altered expression of placental anti-angiogenic factors are responsible for the clinical manifestations of the disease. Soluble Flt1 and soluble endoglin, secreted by the placenta, are increased in the maternal circulation weeks before the onset of preeclampsia. These anti-angiogenic factors produce systemic endothelial dysfunction, resulting in hypertension, proteinuria, and the other systemic manifestations of preeclampsia. The molecular basis for placental dysregulation of these pathogenic factors remains unknown, and as of 2011 the role of angiogenic proteins in early placental vascular development was starting to be explored. The data linking angiogenic factors to preeclampsia have exciting clinical implications, and likely will transform the detection and treatment of preeclampsia.

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

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

The "Great Obstetrical Syndromes" are associated with disorders of deep placentation

Defective deep placentation has been associated with a spectrum of complications of pregnancy including preeclampsia, intrauterine growth restriction, preterm labor, preterm premature rupture of membranes, late spontaneous abortion, and abruptio placentae. The disease of the placental vascular bed that underpins these complications is commonly investigated with targeted biopsies. In this review, we critically evaluate the biopsy technique to summarize the salient types of defective deep placentation, and propose criteria for the classification of defective deep placentation into 3 types based on the degree of restriction of remodeling and the presence of obstructive lesions in the myometrial segment of the spiral arteries.

Midpregnancy levels of angiogenic markers in relation to maternal characteristics

OBJECTIVE

The purpose of this study was to describe relations among maternal demographic and lifestyle characteristics and midpregnancy levels of angiogenic markers (soluble Fms-like tyrosine kinase-1, placental growth factor, soluble endoglin).

STUDY DESIGN

In a large pregnancy cohort, linear models were used to evaluate relations among maternal characteristics and midpregnancy angiogenic markers with and without covariate adjustment. Associations were examined in a subcohort that included term and preterm deliveries (n = 1302) and among "normal" term pregnancies (n = 668).

RESULTS

Concentrations of all factors declined with increasing maternal body mass index. Multiparous women had lower soluble Fms-like tyrosine kinase-1 levels than primiparous women. Higher placental growth factor and slightly lower soluble endoglin levels were observed among women who smoked at enrollment, but not among those women who quit before enrollment. African American women had higher levels of all markers.

CONCLUSION

Understanding relations among maternal characteristics and levels of angiogenic factors may improve studies that use these markers to examine etiology and/or to predict adverse pregnancy outcome.