Unexplained fetal death is associated with increased concentrations of anti-angiogenic factors in amniotic fluid

Objective.?Angiogenesis is critical for successful pregnancy. An anti-angiogenic state has been implicated in preeclampsia, fetal growth restriction and fetal death. Increased maternal plasma concentrations of the anti-angiogenic factor, soluble vascular endothelial growth factor receptor (sVEGFR)-1, have been reported in women with preeclampsia and in those with fetal death. Recent observations indicate that an excess of sVEGFR-1 and soluble endoglin (sEng) is also present in the amniotic fluid of patients with preeclampsia. The aim of this study was to determine whether fetal death is associated with changes in amniotic fluid concentrations of sVEGFR-1 and sEng, two powerful anti-angiogenic factors.

Study design.?This cross-sectional study included patients with fetal death (n?=?35) and controls (n?=?129). Fetal death was subdivided according to clinical circumstances into: (1) unexplained (n?=?25); (2) preeclampsia and/or placental abruption (n?=?5); and (3) chromosomal/congenital anomalies (n?=?5). The control group consisted of patients with preterm labor (PTL) who delivered at term (n?=?92) and women at term not in labor (n?=?37). AF concentrations of sVEGFR-1 and sEng were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied.

Results.?(1) Patients with a fetal death had higher median amniotic fluid concentrations of sVEGFR-1 and sEng than women in the control group (p?<?0.001 for each); (2) these results remained significant among different subgroups of stillbirth (p?<?0.05 for each); and (3) amniotic fluid concentrations of sVEGFR-1 and those of sEng above the third quartile were associated with a significant risk of unexplained preterm fetal death (adjusted OR?=?10.8; 95%CI 1.3–89.2 and adjusted OR 87; 95% CI 2.3–3323, respectively).

Conclusion.?Patients with an unexplained fetal death at diagnosis are characterized by an increase in the amniotic fluid concentrations of sVEGFR-1 and sEng. These observations indicate that an excess of anti-angiogenic factors in the amniotic cavity is associated with unexplained fetal death especially in preterm gestations.     

Unexplained fetal death: Another anti-angiogenic state

Background.?Pregnancy creates a unique situation in which both vasculogenesis and extensive angiogenesis are required for successful fetal and placental development. Recently, the soluble form of vascular endothelial growth factor (VEGF) receptor-1 (sVEGFR-1), an antagonist to VEGF and placental growth factor (PlGF) (two important angiogenic factors), has been implicated in the pathophysiology of preeclampsia and small for gestational age (SGA) without preeclampsia. There is, however, a paucity of information concerning plasma sVEGFR-1 concentrations in other obstetrical disorders. The purpose of this study was to determine plasma sVEGFR-1 concentrations in normal pregnancy, term gestation in labor, and in patients with pregnancy complications including spontaneous preterm labor, preterm premature rupture of the membranes (PROM), fetal death, and acute pyelonephritis.

Methods.?A cross-sectional study was conducted to determine the concentrations of sVEGFR-1 in plasma obtained from 499 women in the following groups: (1) non-pregnant women (n = 40); (2) pregnant women (n = 135); (3) normal pregnant women at term in labor (n = 60); (4) fetal death (n = 60); (5) spontaneous preterm labor with intact membranes (n = 102); (6) preterm PROM (n = 64); and (7) pregnancy with acute pyelonephritis (n = 38). Since plasma sVEGFR-1 concentration changes with gestational age, the difference between the actual and the expected plasma sVEGFR-1 concentration (derived from regression equation of normal pregnancy) for each patient (delta value) was calculated and used to examine the differences of plasma sVEGFR-1 concentrations among various groups. Plasma concentrations of sVEGFR-1 were determined by enzyme-linked immunoassay. Regression analysis and non-parametric statistics were used for analysis.

Results.?(1) Normal pregnant women before term had a median plasma sVEGFR-1 concentration significantly higher than non-pregnant women (p < 0.001); (2) plasma sVEGFR-1 concentration increased with advancing gestational age in normal pregnancy (r = 0.5; p < 0.001); (3) there was no significant difference in the median delta plasma concentration of sVEGFR-1 between normal pregnant women at term with and without labor (p = 0.09); (4) patients with fetal death had a median delta plasma concentration of sVEGFR-1 significantly higher than normal pregnant women (p = 0.001). Among patients with fetal death, those with unexplained causes (p = 0.04) and those with preeclampsia (p < 0.001) had a significantly higher delta plasma sVEGFR-1 concentration than normal pregnant women; and (5) there was no significant difference in the median delta plasma sVEGFR-1 concentration between normal pregnancy and preterm labor with intact membranes, preterm PROM (regardless of the presence or absence of microbial invasion of the amniotic cavity), or acute pyelonephritis (all p > 0.05).

Conclusions.?Plasma sVEGFR-1 concentration is increased in a subset of patients with fetal death, but does not change in term and preterm parturition, rupture of fetal membranes, or acute pyelonephritis.     

Low maternal concentrations of soluble vascular endothelial growth factor receptor-2 in preeclampsia and small for gestational age

Objectives. Preeclampsia is considered an anti-angiogenic state. A role for the anti-angiogenic factors soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and soluble endoglin in preeclampsia has been proposed. Soluble vascular endothelial growth factor receptor-2 (sVEGFR-2) has been detected in human plasma, and the recombinant form of this protein has anti-angiogenic activity. There is a paucity of information about maternal plasma sVEGFR-2 concentrations in patients with preeclampsia and those without preeclampsia with small for gestational age (SGA) fetuses. This study was conducted to determine whether: (1) plasma sVEGFR-2 concentration changes throughout pregnancy; and (2) preeclampsia and SGA are associated with abnormalities in the maternal plasma concentration of sVEGFR-2.

Study design. This cross-sectional study included non-pregnant women (n = 40), women with normal pregnancies (n = 135), women with an SGA fetus (n = 53), and women with preeclampsia (n = 112). SGA was defined as an ultrasound-estimated fetal weight below the 10^th percentile for gestational age that was confirmed by neonatal birth weight. Plasma concentrations of sVEGFR-2 were determined by ELISA.

Results. (1) There was no significant difference in the mean plasma concentration of sVEGFR-2 between non-pregnant women and those with normal pregnancies (p = 0.8); (2) patients with preeclampsia and those without preeclampsia with SGA fetuses had a lower mean plasma concentration of sVEGFR-2 than that of women with normal pregnancies (p < 0.001 for both); and (3) there was no significant difference in the mean plasma concentration of sVEGFR-2 between patients with preeclampsia and those without preeclampsia with SGA (p = 0.9).

Conclusions. Preeclampsia and SGA are associated with low plasma concentrations of sVEGFR-2. One interpretation of the findings is that plasma sVEGFR-2 concentration could reflect endothelial cell function.     

An imbalance between angiogenic and anti-angiogenic factors precedes fetal death in a subset of patients: results of a longitudinal study

Objective.?Women with a fetal death at the time of diagnosis have higher maternal plasma concentrations of the anti-angiogenic factor, soluble vascular endothelial growth factor receptor (sVEGFR)-1, than women with a normal pregnancy. An important question is whether these changes are the cause or consequence of fetal death. To address this issue, we conducted a longitudinal study and measured the maternal plasma concentrations of selective angiogenic and anti-angiogenic factors before the diagnosis of a fetal death. The anti-angiogenic factors studied were sVEGFR-1 and soluble endoglin (sEng), and the angiogenic factor, placental growth factor (PlGF).

Methods.?This retrospective longitudinal nested case–control study included 143 singleton pregnancies in the following groups: (1) patients with uncomplicated pregnancies who delivered a term infant with an appropriate weight for gestational age (n?=?124); and (2) patients who had a fetal death (n?=?19). Blood samples were collected at each prenatal visit, scheduled at 4-week intervals from the first trimester until delivery. Plasma concentrations of sVEGFR-1, sEng, and PlGF were determined by specific and sensitive ELISA. A linear mixed-effects model was used for analysis.

Results.?(1) The average profiles of analyte concentrations as a function of gestational age for sVEGFR-1, sEng and PlGF were different between women destined to have a fetal death and those with a normal pregnancy after adjusting for covariates (p?<?0.05); (2) Plasma sVEGFR-1 concentrations in patients destined to have a fetal death were significantly lower between 7 and 11 weeks of gestation and became significantly higher than those of women with a normal pregnancy between 20 and 37 weeks of gestation (p?<?0.05); (3) Similarly, plasma sEng concentrations of women destined to have a fetal death were lower at 7 weeks of gestation (p?=?0.04) and became higher than those of controls between 20 and 40 weeks of gestation (p?<?0.05); (4) In contrast, plasma PlGF concentrations were higher among patients destined to develop a fetal death between 7 and 14 weeks of gestation and became significantly lower than those in the control group between 22 and 39 weeks of gestation (p?<?0.05); (5) The ratio of PlGF/(sVEGFR-1?×?sEng) was significantly higher in women destined to have a fetal death between 7 and 13 weeks of gestation (94–781%) and significantly lower (44–75%) than those in normal pregnant women between 20 and 40 weeks of gestation (p?<?0.05); (6) Similar results were obtained when patients with a fetal death were stratified into those who were diagnosed before or after 37 weeks of gestation.

Conclusions.?Fetal death is characterised by higher maternal plasma concentrations of PlGF during the first trimester compared to normal pregnancy. This profile changes into an anti-angiogenic one during the second and third trimesters.     

A role of the anti-angiogenic factor sVEGFR-1 in the ‘mirror syndrome’ (Ballantyne's syndrome)

Background.?‘Mirror syndrome’ (Ballantyne's syndrome) refers to the association of fetal hydrops with placentomegaly and severe maternal edema. Preeclampsia occurs in approximately 50% of these cases. Soluble vascular endothelial growth factor receptor-1 (sVEGFR-1), an anti-angiogenic factor, has been implicated in the pathophysiology of preeclampsia (PE).

Objective.?The objective of this study was to determine if the maternal plasma concentration of sVEGFR-1 is elevated in patients with mirror syndrome.

Study design.?This case-control study included patients with uncomplicated pregnancies (n = 40) and those with mirror syndrome (n = 4) matched for gestational age. Mirror syndrome was defined as fetal hydrops and severe maternal edema. Maternal plasma sVEGFR-1 concentrations were determined using specific enzyme-linked immunosorbent assays. Immunohistochemistry of sVEGFR-1 on villous trophoblasts was also performed in samples from one patient with mirror syndrome and compared with those from a patient with spontaneous preterm delivery matched for gestational age. Non-parametric statistics were used for analysis (p < 0.05).

Results.?(1) The median maternal plasma concentration of sVEGFR-1 was significantly higher in patients with mirror syndrome than in the control group (median: 3974 pg/mL, range: 3083–10 780 vs. median: 824 pg/mL, range: 260–4712, respectively; p < 0.001). (2) All patients with mirror syndrome had sVEGFR-1 concentrations above the 95^th percentile for gestational age. Syncytiotrophoblast, especially syncytial knots, showed strong staining with antibodies against sVEGFR-1 in placental samples from the patient with mirror syndrome, but not in those from the patient with spontaneous preterm delivery.

Conclusion.?High maternal plasma concentrations of sVEGFR-1 were observed in mirror syndrome. We propose that this anti-angiogenic factor may participate in the pathophysiology of this syndrome. Thus, maternal plasma determination of sVEGFR-1 may help to identify the hydropic fetus that places the mother at risk for preeclampsia.     

Endocan,a putative endothelial cell marker,is elevated in preeclampsia,decreased in acute pyelonephritis,and unchanged in other obstetrical syndromes

Objective: Endocan, a dermatan sulphate proteoglycan produced by endothelial cells, is considered a biomarker for endothelial cell activation/dysfunction. Preeclampsia is characterized by systemic vascular inflammation, and endothelial cell activation/dysfunction. Therefore, the objectives of this study were to determine whether: (1) plasma endocan concentrations in preeclampsia differ from those in uncomplicated pregnancies; (2) changes in plasma endocan concentration relate to the severity of preeclampsia, and whether these changes are specific or observed in other obstetrical syndromes such as small-for-gestational age (SGA), fetal death (FD), preterm labor (PTL) or preterm prelabor rupture of membranes (PROM); (3) a correlation exists between plasma concentration of endocan and angiogenic (placental growth factor or PlGF)/anti-angiogenic factors (soluble vascular endothelial growth factor receptor or sVEGFR-1, and soluble endoglin or sEng) among pregnancies complicated by preeclampsia; and (4) plasma endocan concentrations in patients with preeclampsia and acute pyelonephritis (both conditions in which there is endothelial cell activation) differ.

Method: This cross-sectional study included the following groups: (1) uncomplicated pregnancy (n?=?130); (2) preeclampsia (n?=?102); (3) pregnant women without preeclampsia who delivered an SGA neonate (n?=?51); (4) FD (n?=?49); (5) acute pyelonephritis (AP; n?=?35); (6) spontaneous PTL (n?=?75); and (7) preterm PROM (n?=?64). Plasma endocan concentrations were determined in all groups, and PIGF, sEng and VEGFR-1 plasma concentrations were measured by ELISA in the preeclampsia group.

Results: (1) Women with preeclampsia had a significantly higher median plasma endocan concentration than those with uncomplicated pregnancies (p?=?0.004); (2) among women with preeclampsia, the median plasma endocan concentration did not differ significantly according to disease severity (p?=?0.1), abnormal uterine artery Doppler velocimetry (p?=?0.7) or whether diagnosis was made before or after 34 weeks gestational age (p?=?0.3); (3) plasma endocan concentration in women with preeclampsia correlated positively with plasma anti-angiogenic factor concentrations [sVEGFR-1: Spearman rho 0.34, p?=?0.001 and sEng: Spearman rho 0.30, p?=?0.003]; (4) pregnancies complicated by acute pyelonephritis with bacteremia had a lower median plasma endocan concentration than pregnancies complicated by acute pyelonephritis without bacteremia (p?=?0.004), as well as uncomplicated pregnancies (p?=?0.001); and (5) there was no significant difference in the median plasma endocan concentration between uncomplicated pregnancies and those complicated by FD, delivery of an SGA neonate, PTL or preterm PROM (other members of the “great obstetrical syndromes”; each p?>?0.05).

Conclusion: Median maternal plasma endocan concentrations were higher preeclampsia and lower in acute pyelonephritis with bacteremia than in uncomplicated pregnancy. No significant difference was observed in the median plasma endocan concentration between other great obstetrical syndromes and uncomplicated pregnancies. The difference in the direction of change of endocan in preeclampsia and acute pyelonephritis with bacteremia may be consistent with the view that both disease entities differ in pathogenic mechanisms, despite their associations with systemic vascular inflammation and endothelial cell activation/dysfunction.     

Unexplained fetal death: another anti-angiogenic state.

BACKGROUND: Pregnancy creates a unique situation in which both vasculogenesis and extensive angiogenesis are required for successful fetal and placental development. Recently, the soluble form of vascular endothelial growth factor (VEGF) receptor-1 (sVEGFR-1), an antagonist to VEGF and placental growth factor (PlGF) (two important angiogenic factors), has been implicated in the pathophysiology of preeclampsia and small for gestational age (SGA) without preeclampsia. There is, however, a paucity of information concerning plasma sVEGFR-1 concentrations in other obstetrical disorders. The purpose of this study was to determine plasma sVEGFR-1 concentrations in normal pregnancy, term gestation in labor, and in patients with pregnancy complications including spontaneous preterm labor, preterm premature rupture of the membranes (PROM), fetal death, and acute pyelonephritis. METHODS: A cross-sectional study was conducted to determine the concentrations of sVEGFR-1 in plasma obtained from 499 women in the following groups: (1) non-pregnant women (n = 40); (2) pregnant women (n = 135); (3) normal pregnant women at term in labor (n = 60); (4) fetal death (n = 60); (5) spontaneous preterm labor with intact membranes (n = 102); (6) preterm PROM (n = 64); and (7) pregnancy with acute pyelonephritis (n = 38). Since plasma sVEGFR-1 concentration changes with gestational age, the difference between the actual and the expected plasma sVEGFR-1 concentration (derived from regression equation of normal pregnancy) for each patient (delta value) was calculated and used to examine the differences of plasma sVEGFR-1 concentrations among various groups. Plasma concentrations of sVEGFR-1 were determined by enzyme-linked immunoassay. Regression analysis and non-parametric statistics were used for analysis. RESULTS: (1) Normal pregnant women before term had a median plasma sVEGFR-1 concentration significantly higher than non-pregnant women (p < 0.001); (2) plasma sVEGFR-1 concentration increased with advancing gestational age in normal pregnancy (r = 0.5; p < 0.001); (3) there was no significant difference in the median delta plasma concentration of sVEGFR-1 between normal pregnant women at term with and without labor (p = 0.09); (4) patients with fetal death had a median delta plasma concentration of sVEGFR-1 significantly higher than normal pregnant women (p = 0.001). Among patients with fetal death, those with unexplained causes (p = 0.04) and those with preeclampsia (p < 0.001) had a significantly higher delta plasma sVEGFR-1 concentration than normal pregnant women; and (5) there was no significant difference in the median delta plasma sVEGFR-1 concentration between normal pregnancy and preterm labor with intact membranes, preterm PROM (regardless of the presence or absence of microbial invasion of the amniotic cavity), or acute pyelonephritis (all p > 0.05). CONCLUSIONS: Plasma sVEGFR-1 concentration is increased in a subset of patients with fetal death, but does not change in term and preterm parturition, rupture of fetal membranes, or acute pyelonephritis.     

The profiles of soluble adhesion molecules in the “great obstetrical syndromes”*

Objective: The objective of this study was to determine the profiles of maternal plasma soluble adhesion molecules in patients with preeclampsia, small-for-gestational-age (SGA) fetuses, acute pyelonephritis, preterm labor with intact membranes (PTL), preterm prelabor rupture of the membranes (preterm PROM), and fetal death.

Materials and methods: A cross-sectional study was conducted to determine maternal plasma concentrations of sE-selectin, sL-selectin, and sP-selectin as well as sICAM-1, sVCAM-1, and sPECAM-1 in patients with (1) an uncomplicated pregnancy (control, n?=?100); (2) preeclampsia (n?=?94); (3) SGA fetuses (in women without preeclampsia/hypertension, n?=?45); (4) acute pyelonephritis (n?=?25); (5) PTL (n?=?53); (6) preterm PROM (n?=?24); and (7) fetal death (n?=?34). Concentrations of soluble adhesion molecules and inflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-8) were determined with sensitive and specific enzyme-linked immunoassays.

Results: In comparison to women with a normal pregnancy, (1) women with preeclampsia had higher median concentrations of sE-selectin, sP-selectin, and sVCAM-1, and a lower concentration of sL-selectin (all p values?p values?p values?p values?p values?p values p values?Conclusions: The results of this study show that endothelial cell activation/dysfunction reflected by the plasma concentration of sE-selectin is not specific to preeclampsia but is present in pregnancies complicated by SGA fetuses, acute pyelonephritis, and fetal death. Collectively, we report that each obstetrical syndrome appears to have a stereotypical profile of soluble adhesion molecules in the peripheral circulation.     

Evidence in support of a role for anti-angiogenic factors in preterm prelabor rupture of membranes

Objective.?Vaginal bleeding, placental abruption, and defective placentation are frequently observed in patients with preterm prelabor rupture of membranes (PROM). Recently, a role of vascular endothelial growth factor (VEGF) and its receptor, VEGF receptor (VEGFR)- 1 has been implicated in the mechanisms of membrane rupture. The purpose of this study was to determine whether the soluble form of VEGFR-1 and -2 concentrations in amniotic fluid (AF) change with preterm PROM, intra-amniotic infection/inflammation (IAI), or parturition.

Study design.?This cross-sectional study included 544 patients in the following groups: (1) midtrimester (MT) (n?=?48); (2) preterm labor (PTL) leading to term delivery (n?=?143); (3) PTL resulting in preterm delivery with (n?=?72) and without IAI (n?=?100); (4) preterm PROM with (n?=?46) and without IAI (n?=?42); (5) term in labor (n?=?48); and (6) term not in labor (n?=?45). The concentrations of sVEGFR-1 and sVEGFR-2 were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied.

Results.?(1) Preterm PROM (with and without IAI) had a lower median AF concentration of sVEGFR-1 than patients with PTL who delivered at term (p?<?0.001 for each comparison); (2) A decrease in AFsVEGFR-1 concentrations per each quartile was associated with PROM after adjusting for confounders (OR 1.8; 95%CI 1.4–2.3); (3) IAI, regardless of the membrane status, was not associated with a change in the median AF concentrations of sVEGFR-1 and sVEGFR-2 (p?>?0.05 for each comparison); and (4) Spontaneous term and PTL did not change the median sVEGFR-1 and sVEGFR-2 concentrations (p?>?0.05 for each comparison).

Conclusion.?(1) This is the first evidence that preterm PROM is associated with a lower AF concentration of sVEGFR-1 than patients with PTL intact membranes. These findings cannot be attributed to gestational age, labor, or IAI; and (2) AF concentrations of sVEGFR-2 did not change with preterm PROM, IAI, or labor at term and preterm.     

The maternal plasma soluble vascular endothelial growth factor receptor-1 concentration is elevated in SGA and the magnitude of the increase relates to Doppler abnormalities in the maternal and fetal circulation

Objectives. The soluble form of vascular endothelial growth factor receptor-1 (sVEGFR-1), an antagonist to vascular endothelial growth factor and placental growth factor, has been implicated in the pathophysiology of preeclampsia. Preeclampsia and pregnancy complicated with small for gestational age (SGA) fetuses share some pathophysiologic derangements, such as failure of physiologic transformation of the spiral arteries, endothelial cell dysfunction, and leukocyte activation. The objectives of this study were to: (1) determine whether plasma concentrations of sVEGFR-1 in mothers with SGA fetuses without preeclampsia at the time of diagnosis are different from those in patients with preeclampsia or normal pregnant women, and (2) examine the relationship between plasma concentrations of sVEGFR-1 and Doppler velocimetry in uterine and umbilical arteries in patients with preeclampsia and those with SGA.

Study design. A cross-sectional study was conducted to determine the concentrations of the soluble form of VEGFR-1 in plasma obtained from normal pregnant women (n = 135), women with SGA fetuses (n = 53), and patients with preeclampsia (n = 112). Patients with SGA fetuses and those with preeclampsia were sub-classified according to the results of uterine and umbilical artery Doppler velocimetry examinations. Plasma concentrations of sVEGFR-1 were determined by an ELISA. Since these concentrations change with gestational age, differences among various subgroups were statistically estimated with the delta value, defined as the difference between the observed and expected plasma sVEGFR-1 concentration. The expected values were derived from regression analysis of plasma sVEGFR-1 concentrations in normal pregnancy. Regression analysis and univariate and multivariate analysis were employed.

Results. (1) Mothers with SGA fetuses had a mean plasma concentration of sVEGFR-1 higher than normal pregnant women (p < 0.001), but lower than patients with preeclampsia (p < 0.001). (2) Among patients with SGA fetuses, only those with abnormal uterine artery Doppler velocimetry had a mean plasma sVEGFR-1 concentration significantly higher than normal pregnant women (p < 0.001). (3) Among mothers with SGA fetuses in whom Doppler velocimetry was performed (n = 41), those with abnormalities in both the uterine and umbilical artery velocimetry had the highest mean delta of sVEGFR-1 plasma concentration (mean ± standard deviation (SD): 0.69 ± 0.29). Conversely, patients who had normal Doppler velocimetry in both uterine and umbilical arteries had the lowest mean delta (mean ± SD: 0.09 ± 0.29) of sVEGFR-1 plasma concentrations (ANOVA; p < 0.001). (4) Among patients with preeclampsia in whom Doppler velocimetry was performed (n = 69), those with abnormalities in both the uterine and umbilical artery velocimetry had the highest mean delta sVEGFR-1 plasma concentration (mean ± SD: 1.01 ± 0.22) among all groups classified (ANOVA; p < 0.001). (5) Among patients with SGA and those with preeclampsia, there was a relationship (Chi-square for trend p < 0.001 for both) between the severity of Doppler velocimetry abnormalities and the proportion of patients who had high delta sVEGFR-1 plasma concentrations (defined as a concentration two standard deviations (2SD) above the mean delta of normal pregnant women). (6) Multiple regression analysis suggested that the diagnostic category (e.g., SGA or preeclampsia), Doppler abnormalities, and gestational age at blood sampling were associated with an increase in plasma sVEGFR-1 concentrations (p < 0.001).

Conclusions. These observations provide support for the participation of the soluble receptor of vascular endothelial growth factor in the pathophysiology of SGA with abnormal uterine artery Doppler velocimetry and preeclampsia. An excess of sVEGFR-1 is released into the maternal circulation of patients with preeclampsia and those with SGA fetuses, as abnormalities of impedance to blood flow involve uterine and umbilical circulation.     

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

Abstract

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.     

Is there any role of prolidase enzyme activity in the etiology of preeclampsia?

Objective: To evaluate a relationship between preeclampsia and prolidase enzyme activity.

Methods: A prospective cohort study of 41 pregnant women diagnosed with preeclampsia and 31 healthy pregnant women as control group was selected at Harran University Hospital Department of Obstetrics and Gynecology. The prolidase enzyme activity was analyzed in maternal and umbilical cord plasma, amniotic fluid and placental and umbilical cord tissues by Chinard method in addition to maternal serum levels of lactate dehydrogenase (LDH), serum glutamate pyruvate transaminase (SGPT) and serum glutamate oxaloacetate transaminase (SGOT).

Results: A significant relationship was found between plasma prolidase activity (635?±?83?U/L) (p =?0.007), umbilical cord plasma prolidase activity (610?±?90?U/L) (p?=?0.013), amniotic fluid prolidase activity (558?±?100?U/L) (p =?0.001), umbilical cord tissue prolidase activity (4248?±?1675?U/gr protein) (p =?0.013) and placental tissue prolidase activity (2116?±?601?U/gr protein) (p =?0.001) in preeclamptic group when compared to healthy pregnant women.

Conclusion: There is a strong correlation between prolidase enzyme activity and preeclampsia. Prolidase enzyme activity may play a role in preeclampsia.     

Maternal plasma concentrations of sST2 and angiogenic/anti-angiogenic factors in preeclampsia

Abstract

Objectives: Angiogenic/anti-angiogenic factors have emerged as one of the promising biomarkers for the prediction of preeclampsia. Since not all patients with preeclampsia can be identified by these analytes, the search for additional biomarkers continues. The soluble form of ST2 (sST2), a protein capable of binding to interleukin (IL)-33 and thus contributing to a Th1-biased immune response, has been reported to be elevated in maternal plasma of women with preeclampsia. The aims of this study were to examine: (1) differences in maternal plasma concentrations of sST2 and IL-33 between women diagnosed with preeclampsia and those having uncomplicated pregnancies; (2) the relationship between sST2, umbilical and uterine artery Doppler velocimetry, and the severity of preeclampsia; and (3) the performance of sST2 and angiogenic/anti-angiogenic factors in identifying patients with preeclampsia at the time of diagnosis.

Methods: This cross-sectional study included women with preeclampsia (n?=?106) and women with an uncomplicated pregnancy (n?=?131). Plasma concentrations of sST2, IL-33, soluble vascular endothelial growth factor receptor (sVEGFR)-1, soluble endoglin (sEng) and placental growth factor (PlGF) were determined by enzyme linked immune sorbent assay. Area under the receiver operating characteristic curve (AUC) for the identification of preeclampsia was examined for each analyte.

Results: (1) Patients with preeclampsia had a higher mean plasma concentrations of sST2 than those with an uncomplicated pregnancy (p?<?0.0001), while no significant difference in the mean plasma concentration of IL-33 between the two groups was observed; (2) the magnitude of this difference was greater in early-onset, compared to late-onset disease, and in severe compared to mild preeclampsia; (3) sST2 plasma concentrations did not correlate with the results of uterine or umbilical artery Doppler velocimetry (p?=?0.7 and p?=?1, respectively) among women with preeclampsia; (4) sST2 correlated positively with plasma concentrations of sVEGFR1-1 and sEng (Spearman’s Rho?=?0.72 and 0.63; each p?<?0.0001), and negatively with PlGF (Spearman’s Rho?=??0.56, p?<?0.0001); and (5) while the AUC achieved by sST2 and angiogenic/anti-angiogenic factors in identifying women with preeclampsia at the time of diagnosis were non-significantly different prior to term (<37 weeks of gestation), thereafter the AUC achieved by sST2 was significantly less than that achieved by angiogenic/anti-angiogenic factors.

Conclusions: Preeclampsia is associated with increased maternal plasma concentrations of sST2. The findings that sST2 concentrations do not correlate with uterine or umbilical artery Doppler velocimetry in women with preeclampsia suggest that elevated maternal plasma sST2 concentrations in preeclampsia are not related to the increased impedance to flow in the utero-placental circulation. The performance of sST2 in identifying preeclampsia at the time of diagnosis prior to 37 weeks of gestation was comparable to that of angiogenic/anti-angiogenic factors. It remains to be elucidated if an elevation of maternal plasma sST2 concentrations in pregnancy is specific to preeclampsia.     

Fetal exposure to tobacco: nicotine and cotinine concentration in amniotic fluid and maternal saliva

Objective: Fetal exposure to tobacco constituents is a risk factor for negative birth outcomes. We aimed to determine the relationships between nicotine and cotinine concentrations in amniotic fluid and maternal saliva.

Methods: As part of a therapeutic trial, 42 pregnant smokers agreed to sample amniotic fluid (8 samples from amniocentesis, 34 at birth). Their smoking characteristics were collected along with the newborns’ birth outcomes.

Results: The median concentrations [IQR] in amniotic fluid and saliva were 11 [7–31] and 38 [7–174] μg/L for nicotine and 72 [22–123] μg/L and 55 [17–109] μg/L for cotinine, respectively. Multivariate models showed that saliva cotinine concentration predicted amniotic fluid nicotine and cotinine concentrations (R^2?=^?0.398, p?R^2?=^?0.708, p?R^2?=^?0.237, p?=?0.002).

Conclusions: Maternal saliva sampling for the determination of cotinine concentration is of interest to monitor fetal exposure to nicotine of any origin. Nevertheless, the time elapsed since the last cigarette was a better predictor of birth weight than the biomarkers’ concentrations in amniotic fluid or maternal saliva.     

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.     

Maternal plasma-soluble ST2 concentrations are elevated prior to the development of early and late onset preeclampsia – a longitudinal study

Objective: The objectives of this study were to determine (1) the longitudinal profile of plasma soluble ST2 (sST2) concentrations in patients with preeclampsia and those with uncomplicated pregnancies; (2) whether the changes in sST2 occur prior to the diagnosis of preeclampsia; and (3) the longitudinal sST2 profile of women with early or late preeclampsia.

Materials and methods: This longitudinal nested case–control study included singleton pregnancies in the following groups: (1) uncomplicated pregnancies (n?=?160); and (2) those complicated by early (<34 weeks, n?=?9) and late (≥34 weeks, n?=?31) preeclampsia. sST2 concentrations were determined by enzyme-linked immunosorbent assays. Mixed-effects models were used for the longitudinal analysis.

Results: (1) Plasma sST2 concentration profiles across gestation differed significantly among cases and controls (p?22 weeks of gestation; cases with late preeclampsia had higher mean concentrations at >33 weeks of gestation (both p?Conclusions: Maternal plasma sST2 concentrations are elevated 6 weeks prior to the clinical diagnosis of preeclampsia. An increase in the maternal plasma concentration of sST2 may contribute to an exaggerated intravascular inflammatory response and/or the Th1/Th2 imbalance in some cases.     

Secreted phospholipase A2 is increased in meconium-stained amniotic fluid of term gestations: potential implications for the genesis of meconium aspiration syndrome

Abstract

Background: Meconium-stained amniotic fluid (MSAF) represents the passage of fetal colonic content into the amniotic cavity. Meconium aspiration syndrome (MAS) is a complication that occurs in a subset of infants with MSAF. Secreted phospholipase A₂ (sPLA₂) is detected in meconium and is implicated in the development of MAS. The purpose of this study was to determine if sPLA₂ concentrations are increased in the amniotic fluid of women in spontaneous labor at term with MSAF.

Materials and methods: This was a cross-sectional study of patients in spontaneous term labor who underwent amniocentesis (n?=?101). The patients were divided into two study groups: (1) MSAF (n?=?61) and (2) clear fluid (n?=?40). The presence of bacteria and endotoxin as well as interleukin-6 (IL-6) and sPLA₂ concentrations in the amniotic fluid were determined. Statistical analyses were performed to test for normality and bivariate analysis. The Spearman correlation coefficient was used to study the relationship between sPLA₂ and IL-6 concentrations in the amniotic fluid.

Results: Patients with MSAF have a higher median sPLA₂ concentration (ng/mL) in amniotic fluid than those with clear fluid [1.7 (0.98–2.89) versus 0.3 (0–0.6), p?<?0.001]. Among patients with MSAF, those with either microbial invasion of the amniotic cavity (MIAC, defined as presence of bacteria in the amniotic cavity), or bacterial endotoxin had a significantly higher median sPLA₂ concentration (ng/mL) in amniotic fluid than those without MIAC or endotoxin [2.4 (1.7–6.0) versus 1.7 (1.3–2.5), p?<?0.05]. There was a positive correlation between sPLA₂ and IL-6 concentrations in the amniotic fluid (Spearman Rho?=?0.3, p?<?0.05).

Conclusion: MSAF that contains bacteria or endotoxin has a higher concentration of sPLA₂, and this may contribute to induce lung inflammation when meconium is aspirated before birth.     

Low maternal concentrations of soluble vascular endothelial growth factor receptor-2 in preeclampsia and small for gestational age.

OBJECTIVES: Preeclampsia is considered an anti-angiogenic state. A role for the anti-angiogenic factors soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and soluble endoglin in preeclampsia has been proposed. Soluble vascular endothelial growth factor receptor-2 (sVEGFR-2) has been detected in human plasma, and the recombinant form of this protein has anti-angiogenic activity. There is a paucity of information about maternal plasma sVEGFR-2 concentrations in patients with preeclampsia and those without preeclampsia with small for gestational age (SGA) fetuses. This study was conducted to determine whether: (1) plasma sVEGFR-2 concentration changes throughout pregnancy; and (2) preeclampsia and SGA are associated with abnormalities in the maternal plasma concentration of sVEGFR-2. STUDY DESIGN: This cross-sectional study included non-pregnant women (n = 40), women with normal pregnancies (n = 135), women with an SGA fetus (n = 53), and women with preeclampsia (n = 112). SGA was defined as an ultrasound-estimated fetal weight below the 10(th) percentile for gestational age that was confirmed by neonatal birth weight. Plasma concentrations of sVEGFR-2 were determined by ELISA. RESULTS: (1) There was no significant difference in the mean plasma concentration of sVEGFR-2 between non-pregnant women and those with normal pregnancies (p = 0.8); (2) patients with preeclampsia and those without preeclampsia with SGA fetuses had a lower mean plasma concentration of sVEGFR-2 than that of women with normal pregnancies (p < 0.001 for both); and (3) there was no significant difference in the mean plasma concentration of sVEGFR-2 between patients with preeclampsia and those without preeclampsia with SGA (p = 0.9). CONCLUSIONS: Preeclampsia and SGA are associated with low plasma concentrations of sVEGFR-2. One interpretation of the findings is that plasma sVEGFR-2 concentration could reflect endothelial cell function.     

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

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

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

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

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

A subset of patients destined to develop spontaneous preterm labor has an abnormal angiogenic/anti-angiogenic profile in maternal plasma: Evidence in support of pathophysiologic heterogeneity of preterm labor derived from a longitudinal study

Objective.?An imbalance between angiogenic and anti-angiogenic factors in maternal blood has been observed in several obstetrical syndromes including preeclampsia, pregnancies with fetal growth restriction and fetal death. Vascular lesions have been identified in a subset of patients with spontaneous preterm labor (PTL). It is possible that PTL may be one of the manifestations of an anti-angiogenic state. The aim of this study was to determine if patients prior to the clinical diagnosis of PTL leading to preterm delivery had plasma concentrations of angiogenic and anti-angiogenic factors different from normal pregnant women.

Study Design.?This longitudinal nested case–control study included normal pregnant women (n?=?208) and patients with PTL leading to preterm delivery (n?=?52). Maternal blood samples were collected at 6 gestational age intervals from 6 to36.9 weeks of gestation. The end point (time of diagnosis) of the study, ‘True PTL’, was defined as patients presenting with PTL and delivered within 1 day. Plasma concentrations of sVEGFR-1, sVEGFR-2, sEng and PlGF were determined by ELISA. Analysis was performed with both cross-sectional and longitudinal (mixed effects model) approaches.

Results. (1) Plasma sEng concentration in patients destined to develop PTL was higher than that in normal pregnant women from 15–20 weeks of gestation. The difference became statistical significant at 28 weeks of gestation, or approximately 5–10 weeks prior to the diagnosis of ‘true PTL’. (2) Backward analysis suggests that plasma concentrations of PlGF and sVEGFR-2 were lower, and those of sVEGFR-1 were higher in patients with PTL than in normal pregnant women less than 5 weeks prior to the diagnosis of ‘true PTL’; and (3) Plasma concentrations of sEng and sVEGFR-1 were higher and those of PlGF and sVEGFR-2 were lower in patients diagnosed with PTL and delivery within 1 day than in normal pregnant women who delivered at term.

Conclusion.?The changes in sEng are demonstrable several weeks prior to the onset of preterm parturition. In contrast, the changes in the other angiogenic proteins are present close to the onset of PTL and delivery. This observation supports the view that an imbalance of angiogenic factors participates in the pathophysiology of spontaneous preterm parturition.