Recent Insights into the pathogenesis of pre-eclampsia

Agonistic antibodies directed at the angiotensin II, AT1 receptor in preeclampsia

Immune mechanisms and circulating mediators may be important in the pathogenesis of preeclampsia. We review our findings on agonistic antibodies against the angiotensin II (Ang II) receptor (AT1-AA) and their possible role in the pathogenesis of this disorder. AT1-AA appear in the course of preeclampsia and are largely gone by 6 weeks after delivery. AT1-AA detection relies on a bioassay using spontaneously beating neonatal rat cardiomyocytes. Their specificity has been documented by other methods, including Western blotting, co-localization, and co-immunoprecipitation experiments. AT1-AA induce signaling in vascular cells and trophoblasts including transcription factor activation. The signaling results in tissue factor production and reactive oxygen species generation, both of which have been implicated in preeclampsia. The role of AT1-AA in preeclampsia and other severe hypertensive conditions has not yet been proved with certainty. However, we believe the findings are compelling and warrant further study.

Population pharmacokinetics of ketanserin in pre-eclamptic patients and its association with antihypertensive response

Ketanserin is an antihypertensive drug that is increasingly being used parenterally in the treatment of pre-eclampsia. Because of lack of efficacy in a substantial part of our pre-eclamptic patients, we determined the plasma concentrations of ketanserin in 51 pre-eclamptic patients. Population pharmacokinetic parameters were assessed using the iterative two-stage Bayesian population procedure. The influence of individual pharmacokinetic parameters on antihypertensive response, expressed as the attainment of a diastolic blood pressure <or=90 mmHg using ketanserin treatment, was analysed. Almost all plasma concentrations of ketanserin were in or above the therapeutic range. The individual pharmacokinetics of ketanserin in pre-eclamptic patients showed an accurate fit using a three-compartment model. The pharmacokinetic parameters in our pre-eclamptic population were a metabolic clearance (Cl(m)) of 37.9+/-10.86 L/h and volume of distribution (V1) of 0.544+/- 0.188 L/kg, which is comparable with data from healthy volunteers. Despite a considerable inter-individual variation, no correlation was found between differences in pharmacokinetic parameters and antihypertensive response. We conclude that therapeutic plasma levels can be obtained in pre-eclamptic patients with a fixed dosage schedule of ketanserin and differences in antihypertensive responses within a pre-eclamptic population cannot be attributed to pharmacokinetic differences.

Effect of preeclampsia on blood pressure in newborn very low birth weight infants

OBJECTIVE

To test the hypothesis that very low birth infants born to mothers with preeclampsia have higher blood pressure over the first week of life than infants whose mothers did not have preeclampsia.

METHOD

Infants born at<1,350 g who survived at least one week were stratified by gestational age ( <or= 28 weeks and >or= 29 completed weeks) and grouped by the presence or absence of preeclampsia. Highest and lowest systolic and mean and diastolic blood pressures were recorded for each of the first seven days of life. Serial blood pressures were analyzed by repeated measures ANOVA: The presence of hypertension (defined as >or= 3 days with the highest systolic blood pressure>90th percentile for gestational age stratum and day-specific range) was analyzed by binary logistic regression.

RESULTS

Infants >or= 29 weeks gestational age born to mothers with preeclampsia had higher blood pressures than did controls. Infants <or= 28 weeks gestational age born to preeclamptic and non-preeclamptic mothers had similar blood pressures. In the combined cohort, hypertension was not more prevalent among infants born to women with preeclampsia.

CONCLUSIONS

Preeclampsia is associated with higher blood pressure in very low birth weight neonates who are >or= 29 weeks gestation. The long-term significance of this finding is not known.

Genomewide oligonucleotide microarray analysis on placentae of pre-eclamptic pregnancies

OBJECTIVE

Human placentae from normal and pre-eclamptic pregnancies were evaluated for possible changes in gene expression by microarray analysis to uncover new clues for the research of the etiology of pre-eclampsia.

METHODS

Placentae from five normal pregnancies and five pregnancies complicated by pre-eclampsia were collected. mRNA levels of five pre-eclamptic placentae were examined using genome-wide 70-mer oligonucleotide microarrays (CapitalBio, Beijing, China) in comparison with the pooled control consisting of total RNA from five normotensive placentae.

RESULTS

Ninety-six genes were found consistently down- or up-regulated in at least four pre-eclamptic samples. Most of them were related to an imbalance of reactive oxygen metabolites in placenta, abnormal trophoblast invasion, disorders of lipoprotein metabolism and signal transduction, or some that have been reported to have close correlation to the pathology of pre-eclampsia. The microarray data were also confirmed by the measurement of real-time PCR.

CONCLUSION

DNA microarray is a high throughput and time-saving method to monitor altered gene expression. The results could provide interesting clues to the etiology of pre-eclampsia and lead to further studies in a more targeted fashion.

Exercise or other physical activity for preventing pre-eclampsia and its complications

BACKGROUND

The association between an increase in regular physical activity and a reduction in the risk of hypertension is well documented for non-pregnant people. It has been suggested that exercise may help prevent pre-eclampsia and its complications. Possible adverse effects of increased physical activity during pregnancy, particularly on the risk of preterm birth and fetal growth restriction, are unclear. It is, therefore, important to assess whether exercise reduces the risk of pre-eclampsia and its complications and, if so, whether these benefits outweigh the risks.

OBJECTIVES

To assess the effects of exercise, or increased physical activity, on prevention of pre-eclampsia and its complications.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (December 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2005, Issue 1), and EMBASE (2002 to February 2005).

SELECTION CRITERIA

Studies were included if these were randomised trials evaluating the effects of exercise or increased physical activity during pregnancy for women at risk of pre-eclampsia.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted data. Data were entered on Review Manager software for analysis, and double checked for accuracy.

MAIN RESULTS

Two small, good quality trials (45 women) were included. Both compared moderate intensity regular aerobic exercise with maintenance of normal physical activity during pregnancy. The confidence intervals were wide and crossed the line of no effect for all reported outcomes including pre-eclampsia (relative risk 0.31, 95% confidence interval 0.01 to 7.09).

AUTHORS' CONCLUSIONS

There is insufficient evidence for reliable conclusions about the effects of exercise on prevention of pre-eclampsia and its complications.

Enhanced Endothelin Synthesis by Endothelial Cells Exposed to Sera From Pregnant Rats With Decreased Uterine Perfusion

The initiating event in preeclampsia is thought be to reduced uteroplacental perfusion. Although we have reported previously that chronic reductions in uterine perfusion pressure (RUPP) in pregnant rats results in hypertension and enhanced endothelin production, the factors linking placental ischemia and endothelial cell activation remain unclear. The purpose of this study was to determine the role of angiotensin II type-1 (AT1) receptor activation on endothelin production induced by serum from pregnant rats exposed to reductions in uterine perfusion. To achieve this goal, human umbilical vein endothelial cells were exposed to sera collected from RUPP rats or normal pregnant rats. Arterial pressure was significantly higher in RUPP rats (135+/-2 mm Hg) than in pregnant rats (106+/-1 mm Hg). Six hours after exposure to RUPP serum (n=17), cell media endothelin concentration was 18.4+/-2.7 pg/mL as compared with 9.22+/-1.3 pg/mL from cells exposed to serum from normal pregnant rats (n=9). Eighteen hours after exposure to RUPP serum (n=7), endothelin concentration was 30.5+/-3.8 pg/mL as compared with 12.8+/-5.3 pg/mL from cells exposed to normal pregnant rat serum (n=6). In contrast, serum from RUPP rats did not increase endothelin production in human umbilical vein endothelial cells pretreated with an AT1 receptor antagonist, losartan (15 micromol/L). Eighteen hours after exposure to RUPP serum and losartan (n=14), endothelin concentration was 21.3+/-2.2 pg/mL as compared with 16.4+/-3.3 pg/mL from cells exposed to normal pregnant rat serum and losartan (n=10). These data indicate that serum from pregnant rats exposed to reductions in uterine perfusion enhances endothelin production by endothelial cells via by AT1 receptor activation.

Suppressive effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on vascular remodeling that takes place in the normal labyrinth zone of rat placenta during late gestation

The maintenance of the placental vasculature is essential for sustaining normal fetal growth. On the basis of our previous observation that fetal death was accompanied by placental hypoxia upon exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (R. Ishimura et al., 2002a, Toxicol. Appl. Pharmacol. 185, 197-206), we here investigated the effects of TCDD on the placenta, focusing on the development of the labyrinth zone. Holtzman rats were administered a single oral dose of 1.6 mug of TCDD/kg body weight or an equivalent volume of vehicle (control) on gestation day (GD) 15, and placental tissues were analyzed on GD20. Immunohistochemical staining showed that the exposure to TCDD decreased the size of maternal blood sinusoids and caused the constriction of fetal capillaries in the placenta. In contrast, we found that vascular remodeling occurred in the labyrinth zone of normal rat placenta; that is, the vascular development in the normal labyrinth zone during the late gestation (from GD16 to GD20) showed dilated maternal blood sinusoids and fetal capillaries accompanied by a decrease in thickness and the apoptosis of trophoblasts. The present results demonstrate that this remodeling is suppressed by TCDD, which is further supported by the decreased expression level of Tie2 mRNA, the gene which is associated with vascular remodeling, and also by the decrease in the number of apoptotic trophoblasts in TCDD-exposed rats. The present study provided a new finding on the development of the vasculature in the labyrinth zone during the late gestation under normal conditions and showed the inhibition of vascular remodeling in TCDD-exposed rats.

Placental oxidative stress in a rat model of preeclampsia

The onset of preeclampsia is associated with increased maternal insult that could affect placental function. By increasing sodium intake (0.9% or 1.8% NaCl in drinking water) during the last week of gestation in the rat, we developed an animal model that shows many characteristics of preeclampsia such as increased blood pressure, decreased circulatory volume and diminished activity of the renin-angiotensin-aldosterone system. The aim of the present study was to determine in this model whether maternal perturbations in pregnancy lead to placental oxidative stress. Sprague-Dawley pregnant rats receiving salted-water were compared to not-supplemented pregnant rats. Markers of oxidative stress, ensuing cell death, and changes in the production of vasoactive substances (prostanoids: thromboxane, TxB(2); and prostacyclin, PGF(1alpha)) and the pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-alpha) were measured in the placenta. In tissue from pregnant rats on 1.8% NaCl supplement, 8-iso-PGF(2alpha) levels, TxB(2)/6-keto-PGF(1alpha) ratios, total TNF-alpha RNA expression, as well as the apoptotic index (Bax/Bcl-2 ratio) and endothelial nitric oxide synthase protein expression increase while total glutathione content decreases. These findings demonstrate that maternal insult during gestation induced an imbalance in the oxidative environment in the placenta favouring oxidation. This was accompanied by an increased synthesis of vasoconstrictive substances and TNF-alpha by the placenta as well as the increased rate of placental cell apoptosis.

Circulating angiogenic factors in preeclampsia, gestational proteinuria, and preeclampsia superimposed on chronic glomerulonephritis

OBJECTIVE

Recently, reports have indicated that the imbalance of circulating angiogenic factors is important in the onset of preeclampsia. In this study we investigated angiogenic factor levels in women with preeclampsia, preeclampsia superimposed on chronic glomerulonephritis, gestational proteinuria, and normal pregnancies.

STUDY DESIGN

We measured several circulating angiogenic factors, placental growth factor, vascular endothelial growth factor, soluble fms-like tyrosine kinase-1, and soluble fetal liver kinase-1.

RESULTS

Compared with women with normal pregnancies, placental growth factor concentrations were lower, and soluble fms-like tyrosine kinase 1 concentrations were higher in women with preeclampsia and gestational proteinuria; soluble fms-like tyrosine kinase 1 concentrations were also higher in women with preeclampsia superimposed on chronic glomerulonephritis.

CONCLUSION

There were obvious differences in the levels of circulating angiogenic factors placental growth factor and soluble fms-like tyrosine kinase 1 among preeclampsia, gestational proteinuria, and controls. The imbalance of angiogenic factors is important in the onset of preeclampsia superimposed on chronic glomerulonephritis.

The effect of maternal characteristics on endothelial-dependent relaxation of myometrial arteries

OBJECTIVE

Endothelial dysfunction is central to the pathogenesis of pre-eclampsia (PE). This study aimed to determine if maternal characteristics, such as age, parity, BMI, smoking status and obstetric history, which affect the risk of developing pre-eclampsia, influenced endothelial function in myometrial arteries taken during an uncomplicated pregnancy.

STUDY DESIGN

As part of ongoing studies investigating endothelial function in normal and compromised pregnancies, myometrial vessels were isolated from biopsies taken at elective Caesarean section. A cohort of 119 women was identified and information regarding past pregnancy outcomes and medical history was obtained. Wire myography was used to compare endothelial-dependent relaxation in response to bradykinin between different patient groups.

RESULTS

Maternal age, parity and a history of miscarriage did not affect endothelial-dependent relaxation of myometrial small arteries. Attenuated endothelial-dependent relaxation was seen in vessels taken from women with elevated BMI and enhanced relaxation was seen in women who had smoked during pregnancy. Vessels isolated from women with a history of past pregnancy complications did not show any significant difference in endothelial-dependent relaxation compared to women with uncomplicated histories.

CONCLUSION

Maternal factors may influence endothelial function in the absence of pregnancy complications. Endothelial-dependent relaxation of myometrial arteries, isolated from multiparous women with an uncomplicated index pregnancy, is comparable between women with and without a history of pregnancy complications.

Determination of Non-bilayer Phospholipid Arrangements and their Antibodies in Placentae and Sera of Patients with Hypertensive Disorders of Pregnancy

Studies suggest that preeclampsia (PE) originates in the placenta and is associated with deficient trophoblast invasion of spiral arteries. The direct cause remains unknown, but preeclampsia is often associated with circulating factors that can induce generalized endothelial dysfunction. Antiphospholipid antibodies (APA) in circulation are also associated with vascular diseases. Although the quantification of APA is not currently used as a prognostic of the risk of PE, studies suggest that thrombophilias play a role in PE pathogenesis. In fact, the pathology of placentae from PE and Antiphospholipid syndrome patients is similar; atherosis, thrombosis and infarction, and endothelium activation represent the pathological mechanisms. We identified a new antibody which recognizes non-bilayer phospholipid arrangements (NPA) in membrane models and in cell membranes in vivo, and which triggered an autoimmune-like disease in mice. We evaluated the presence of NPA in the placentae and in sera, and whether NPA induced NPA antibodies in patients with hypertensive disorders of pregnancy (HDP). Results showed increased levels of NPA in the syncytiotrophoblast, extravillous cytotrophoblast, syncytial knots and the amnion epithelial cell membranes of the placenta, as well as increases in NPA and NPA antibodies in sera from HDP patients, when compared with controls. This suggests that NPA derived from placenta could be one of multiple factors associated with pregnancy pathologies.

Adverse perinatal outcome and later kidney biopsy in the mother

Strong associations of adverse perinatal outcomes have been identified with later cardiovascular disease in the mother. Few studies have addressed associations with kidney disease. This study investigated whether perinatal outcomes are associated with later clinical kidney disease as diagnosed by kidney biopsy. The Medical Birth Registry of Norway contains data on all childbirths in Norway since 1967. The Norwegian Kidney Biopsy Registry contains data on all kidney biopsies in Norway since 1988. All women with a first singleton delivery from 1967 to 1998 were included. Pregnancy-related predictors of later kidney biopsy were analyzed by Cox regression analyses. A total of 756,420 women were included, and after a mean period of 15.9+/-9.4 yr, 588 had a kidney biopsy. Compared with women without preeclampsia and with offspring with birth weight of >or=2.5 kg, women with no preeclampsia and with offspring with birth weight of 1.5 to 2.5 kg had a relative risk (RR) for a later kidney biopsy of 1.7, women with no preeclampsia and with offspring with birth weight of <1.5 kg had an RR of 2.9, women with preeclampsia and with offspring with a birth weight of >or=2.5 kg had an RR of 2.5, women with preeclampsia and with offspring with a birth weight of 1.5 to 2.5 kg had an RR of 4.5, and women with preeclampsia and with offspring with a birth weight of <1.5 kg had an RR of 17. Similar results were found in adjusted analyses and after exclusion of women with diabetes, kidney disease, or rheumatic disease before pregnancy. The same risk patterns applied to any of the specific categories of kidney disease as well as specific kidney diseases investigated. Women who have preeclampsia and give birth to offspring with low birth weight and short gestation have a substantially increased risk for having a later kidney biopsy.

Serum iron and copper status and oxidative stress in severe and mild preeclampsia

Our aim was to investigate parameters of iron and copper status and oxidative stress and antioxidant function in women with healthy pregnancy, mild and severe preeclampsia with a view to exploring the possible contribution of these parameters to the aetiology. Thirty healthy, 30 mild preeclamptic and 30 severe preeclamptic pregnant women were included. Serum and placental lipid peroxides, and serum vitamin E and total carotene levels were measured by colorimetric assay. Cholesterol, copper, iron, total iron binding capacity (TIBC), ceruloplasmin and transferrin concentrations were measured by commercially available procedures. Data were analysed statistically using one-way analysis of variance and Pearson correlation test. Logistic regression procedures were used to calculate odds ratios. Lipid peroxides in serum and placental tissue, and iron, copper and ceruloplasmin levels in serum were significantly increased, and transferrin, TIBC, vitamin E/total cholesterol and total carotene/total cholesterol ratios in serum were significantly decreased especially in women with severe preeclampsia. Significant correlations were detected between serum iron and lipid peroxides in serum and placental tissue and between serum iron and vitamin E/total cholesterol in severe preeclamptic pregnancy. Furthermore, there were significant correlations between serum malondialdehyde and ceruloplasmin and vitamin E/total cholesterol in women with severe preeclampsia, and changes in serum and placental lipid peroxides and serum iron concentrations were significantly associated with preeclampsia. In conclusion, ischaemic placental tissue may be a primary source of potentially toxic iron in preeclampsia and the released iron species may contribute to the aetiology and would exacerbate lipid peroxidation and endothelial cell injury, which may be abated by antioxidant supplementation.

Tracing the origins of “fetal origins” of adult diseases: Programming by oxidative stress?

Too small size at birth (due to poor fetal growth and/or preterm delivery) has been associated with substantially elevated risks of the metabolic syndrome (dislipidemia, insulin resistance, hypertension), type 2 diabetes and cardiovascular disease in adulthood. The mechanisms of such "fetal origins" or "programming" of disease phenomenon remain unresolved. Too large size at birth seems also associated with an increased risk. Many known or suspected causes of or conditions associated with adverse (poor or excessive) fetal growth or preterm birth have been associated with oxidative stress. Plausibly, oxidative stress may be a common link underlying the superficial "programming" associations between adverse fetal growth or preterm birth and elevated risks of certain chronic diseases. The mechanisms of oxidative stress programming may be through directly modulating gene expression or indirectly through the effects of certain oxidized molecules. Experimental investigations have well demonstrated the role of redox balance in modulating gene expression, and recent studies indicate that both the insulin functional axis and blood pressure could be sensitive targets to oxidative stress programming. Adverse programming may occur without affecting fetal growth, but more frequently among low birth weight infants merely because they more frequently experienced known or unknown conditions with oxidative insults. As oxidative stress levels are easily modifiable during pregnancy and early postnatal periods (which are plausible critical windows), the hypothesis, if proved valid, will suggest new measures that could be very helpful on fighting the increasing epidemic of the metabolic syndrome, type 2 diabetes and cardiovascular disease. Currently, there are several ongoing large randomized trials of antioxidant supplementation to counter oxidative stress during pregnancy for the prevention of preeclampsia. It would be invaluable if long-term follow-ups of infants born to women in such trials could be realized to test the oxidative stress programming hypothesis in such experimental trial settings.

Circulating concentrations of sFlt1 (soluble fms-like tyrosine kinase 1) in fetal and maternal serum during pre-eclampsia

OBJECTIVE

We hypothesized that umbilical vein serum soluble fms-like tyrosine kinase 1 (sFlt1) concentration was augmented in pre-eclampsia. We also explored a possible association between fetal and maternal concentrations of sFlt1.

STUDY DESIGN

At cesarean delivery, maternal serum samples from pre-eclamptic (n=38) and uncomplicated (n=32) pregnancies were obtained, as well as umbilical vein serum and amniotic fluid samples. ELISA for human sFlt1, vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) were performed.

RESULTS

Median sFlt1 concentrations were elevated in pre-eclampsia compared to uncomplicated pregnancy, in umbilical venous serum (246 and 163 pg/mL, P=0.04), in maternal serum (9932 and 3417 pg/mL, P<0.001), as well as in amniotic fluid (51,040 and 33,490 pg/mL, P=0.03). A positive association between the fetal and maternal serum levels of sFlt1 was found in the pre-eclampsia group. Median PlGF concentration in the maternal serum was significantly lower in the pre-eclampsia group compared to the control group (82 pg/mL and 169 pg/mL, P<0.001).

CONCLUSIONS

sFlt1 concentration is elevated in the fetal circulation in pre-eclampsia, but at a much lower level than in the maternal circulation. The results of our study do not support a substantial fetal contribution to the elevated circulating maternal sFlt1 protein concentration in pre-eclampsia.

The risk of preeclampsia rises with increasing prepregnancy body mass index

PURPOSE

To explore the dose-dependent relation between prepregnancy body mass index (BMI) and the risk of preeclampsia after adjusting for measured confounders.

METHODS

We studied 1179 primiparous women who enrolled at < 16 weeks' gestation into a prospective cohort study of the pathogenesis of preeclampsia. Multivariable logistic regression was used to quantify the independent effect of prepregnancy BMI on the risk of preeclampsia after adjusting for race and smoking status. BMI was specified as a restricted quadratic spline.

RESULTS

Preeclampsia risk rose strikingly from a BMI of 15 to 30 kg/m(2). Compared with women with a BMI of 21, the adjusted risk of preeclampsia doubled at a BMI of 26 (odds ratio 2.1 [95% confidence interval, 1.4, 3.4]), and nearly tripled at a BMI of 30 (2.9 [1.6, 5.3]). Women with a BMI of 17 had a 57% reduction in preeclampsia risk compared with women with a BMI of 21 (0.43 [0.25, 0.76]), and a BMI of 19 was associated with a 33% reduction in risk (0.66 [0.50, 0.87]).

CONCLUSIONS

These results indicate that preeclampsia risk rises through most of the BMI distribution. The dramatic elevation in overweight prevalence in the United States may increase preeclampsia incidence in the future.

Preeclampsia

Preeclampsia is a pregnancy complication with serious consequences for mother and infant. The disorder is diagnosed by gestational hypertension and proteinuria but is far more than pregnancy induced hypertension. Preeclampsia is proposed to occur in 2 stages. Stage 1 reduced placental perfusion is postulated as the root cause and to lead to the maternal syndrome, Stage 2. Why perfusion is reduced, how this translates to a maternal disease in some but not all women and what is the linkage of the 2 stages are topics of intense study. In the last decade such studies have provided valuable insights into pathophysiology that now guide ongoing clinical trials.

Placental insufficiency leads to developmental hypertension and mesenteric artery dysfunction in two generations of Sprague-Dawley rat offspring

It is generally accepted that preeclampsia results from reduction in perfusion to the uteroplacental unit leading to maternal hypertension and fetal growth restriction. Placental insufficiency creates an environment of fetal undernutriton, predisposing the fetus to the development of adult disease. In this study, we characterized the development and perpetuation of hypertension in two generations of male and female offspring subjected to an environment of fetal undernutrition via reduced uteroplacental perfusion pressure. Further, we examined vascular responses of resistance arteries in these animals to determine the influence of placental insufficiency on the development and perpetuation of hypertension. Experimental dams underwent a surgical procedure to reduce uteroplacental perfusion pressure, with resulting offspring comprising the first generation (F1). One male and one female from each of the F1 experimental litters served as breeders of the second generation (F2). Weekly systolic blood pressure measurements were obtained from 4 to 24 wk in control, F1, and F2 offspring. Vascular responsiveness to the vasoconstrictors phenylephrine and potassium chloride and the vasorelaxants acetylcholine and sodium nitroprusside was determined in the three offspring groups at 6, 9, and 12 wk of age. Our findings indicate that placental insufficiency during a critical developmental window in late gestation leads to hypertension in juvenile Sprague-Dawley rat offspring and is perpetuated in a second generation of offspring in a gender-specific manner. Further, exposure to placental insufficiency during late gestation leads to developmental alterations characterized by vascular hyperresponsiveness, perpetuated to a second generation of offspring in the absence of persistent environmental stimuli, contributing to hypertension.

Maternal cigarette smoking and the risk of pregnancy-induced hypertension and eclampsia

BACKGROUND

Although previous studies have found that maternal smoking decreases the risk of pregnancy-induced hypertension (PIH), the difference of this effect between primiparous and multiparous women has not been well studied and the results of the exposure-response relationships between maternal smoking and PIH are inconsistent. No previous study has specifically examined the relationship between maternal smoking and eclampsia.

METHODS

We analysed data from a population-based retrospective cohort study of 3 153 944 singleton pregnancies in the US. The data were derived from the national linked birth/infant mortality database for 1998. Multiple logistic regressions were used to describe the relationship between cigarette smoking and PIH and eclampsia.

RESULTS

The adjusted odds ratios (ORs) [95% confidence intervals (95% CIs)] for PIH were 0.80 (0.77-0.83) for primiparous women and 0.81 (0.78-0.83) for multiparous women among smokers compared with non-smokers. The corresponding adjusted ORs (95% CIs) for eclampsia were 0.74 (0.66-0.82) and 0.75 (0.68-0.83), respectively. For PIH, the adjusted OR (95% CI) for smokers vs non-smokers were 0.82 (0.79-0.86), 0.81 (0.78-0.83), 0.80 (0.77-0.83), and 0.88 (0.79-0.98), respectively, for 1-5, 6-10, 11-20, and >20 cigarettes per day (test for trend: P = 0.86). The corresponding figures for eclampsia were 0.85 (0.75-0.95), 0.74 (0.66-0.82), 0.68 (0.58-0.78), and 0.73 (0.49-1.04), respectively (test for trend: P = 0.02).

CONCLUSION

Maternal cigarette smoking decreases the risk of PIH and eclampsia, with a significant inverse exposure-response relationship apparent for eclampsia.

Human chorionic gonadotropin (hCG) may be a marker of systemic oxidative stress in normotensive and preeclamptic term pregnancies

OBJECTIVES

In vitro studies on placental function have revealed interactions between levels of secretion of human chorionic gonadotropin (hCG) by trophoblastic cells and oxidative stress generated by hydrogen peroxide (H2O2). Here, we have examined the relationship between maternal levels of hCG and H2O2 in vivo in term pregnancies with and without preeclampsia.

DESIGN AND METHODS

We measured serum levels of hCG and H2O2 in twenty preeclamptic and twenty normotensive term pregnant women (controls), using an enzymatic immunoassay and an electrochemical method, respectively.

RESULTS

Higher levels of serum hCG and H2O2 were observed in patients with preeclampsia in comparison to controls. A significant positive correlation between serum hCG concentration and H2O2 production was found.

CONCLUSION

Our results show that: (1) systemic hCG levels are correlated with an oxidative stress state in term pregnant women with preeclampsia and (2) circulating hCG may be a monitoring tool of oxidative stress during pregnancy.

L’IRM fonctionnelle pour l’étude de la fonction placentaire

Placental insufficiency, a process due to either poor placental perfusion or permeability, may lead to progressive deterioration in placental function and materno-fetal morbidity. Advances in MR contrast media pharmacokinetic studies of transit through tissues and dynamic MRI allow to characterize organs microcirculation in vivo. Placental function assessment might be achieved using analysis of dynamic contrast enhanced MRI of tracers. A murine model of placental assessment has been constructed. Herein, principles, results and limitations of such techniques are discussed as well as their potential interest and weaknesses in humans.

Risk for Coronary Artery Disease and Morbid Preeclampsia: A Commentary

PURPOSE

A predisposition to coronary artery disease (CAD) may put women at risk for preeclampsia. Morbid preeclampsia (early, severe, recurrent, and with neonatal morbidity) represents the subset of preeclampsia of greatest public health concern.

METHODS

We review here the published links between preeclampsia and CAD.

RESULTS

Many risk factors are common to both CAD and preeclampsia. These include obesity; elevated blood pressure; dyslipidemia; insulin resistance; and hyperglycemia, together termed "Syndrome X"; as well as endothelial dysfunction; hyperuricemia; hyperhomocysteinemia; and abnormalities of inflammation, thrombosis, and angiogenesis. After pregnancy, women with preeclampsia are more likely to experience later life CAD.

CONCLUSIONS

Both the association between CAD risk factors and preeclampsia and the association between preeclampsia and later CAD appears to be more pronounced among the subset of women with morbid preeclampsia. Thus, women at elevated risk for CAD may be at particularly high risk for morbid preeclampsia and women with morbid preeclampsia may be those at highest risk for later life CAD.

Screening test for preeclampsia through assessment of uteroplacental blood flow and biochemical markers of oxidative stress and endothelial dysfunction

OBJECTIVE

This study was undertaken to evaluate whether screening through a uterine artery (UtA) Doppler and biochemical markers of oxidative stress and endothelial dysfunction predict preeclampsia.

STUDY DESIGN

UtA Doppler was performed at 11 to 14 and 22 to 25 weeks on 1447 asymptomatic pregnant women. Oxidative stress, endothelial dysfunction, and antiangiogenic state were assessed in women who later developed preeclampsia and normotensive controls.

RESULTS

There was a significantly increased of UtA pulsatility index (PI), plasma levels of soluble fms-like tyrosine kinase 1 (sFlt1), PAI-1/PAI-2 ratio, and F-2 isoprostane in women who subsequently developed preeclampsia compared with control pregnancies. Multivariate logistic regression showed that increased UtA PI performed at 23 weeks was the best predictor for preeclampsia.

CONCLUSION

This study demonstrates early changes in markers of impaired placentation, antiangiogenic state, oxidative stress, and endothelial dysfunction suggesting that these derangements may play a role in the pathogenesis of preeclampsia. Our data point to UtA as the best test to predict preeclampsia at 23 weeks of gestation.

Stimulation of the ADRB3 adrenergic receptor induces relaxation of human placental arteries: influence of preeclampsia

Preeclampsia, which complicates 3-8% of pregnancies, is one of the leading causes of neonatal morbidity and mortality. Its pathophysiology remains unclear. The aim of the present study was to investigate the presence and the role of beta2- and beta2-adrenergic receptors (ADRB2 and ADRB3, respectively) in human placental arteries and to assess the influence of preeclampsia on ADRB responsiveness. SR 59119A, salbutamol, and isoproterenol (ADRB3, ADRB2, and nonselective ADRB agonists, respectively) induced a concentration-dependent relaxation of placental artery rings obtained from women with uncomplicated or preeclamptic pregnancies. SR 59119A-induced relaxation was unaffected by the blockade of ADRB1 and ADRB2 by 0.1 microM propranolol but was significantly decreased by the blockade of ADRB1, ADRB2, and ADRB3 by 10 microM propranolol. Both SR 59119A and salbutamol were associated with a significant increase in cAMP production that was significantly inhibited by pretreatment with 0.1 microM propranolol only for salbutamol. SR 59119A-induced relaxation (E(max) = 28% +/- 5% vs. 45% +/- 4%, respectively) and cAMP production (2.7 +/- 0.5 vs. 4.9 +/- 0.4 pmol/mg of protein, respectively; P < 0.01) were decreased in arteries obtained from preeclamptic compared to normotensive women. Both ADRB2 and ADRB3 transcripts were expressed at the same level between arteries from normotensive and preeclamptic women. Western blot analysis, however, revealed a decreased expression of the ADRB3 immunoreactive protein in arteries from preeclamptic compared to normotensive women. We suggest the presence of functional ADRB2 and ADRB3 in human placental arteries. Even if preeclampsia is associated with an impairment of the ADRB3 responsiveness, ADRB3 agonists may have future pharmaceutical implications in the management of pregnancy-related disorders.

An elevated maternal plasma, but not amniotic fluid, soluble fms-like tyrosine kinase-1 (sFlt-1) at the time of mid-trimester genetic amniocentesis is a risk factor for preeclampsia

OBJECTIVE

The purpose of this study was to determine if an elevated concentration of soluble fms-like tyrosine kinase-1(sFlt-1) in maternal plasma and amniotic fluid is a risk factor for the subsequent development of preeclampsia.

STUDY DESIGN

A case-control study was conducted to compare mid-trimester concentrations of maternal plasma and amniotic fluid sFlt-1 in patients who developed preeclampsia with those who did not. The study included 32 cases with preeclampsia (18 cases: severe preeclampsia) and 128 matched controls with normal outcomes. Patients with an abnormal fetal karyotype or major anomaly, multiple pregnancies, chronic hypertension, diabetes, and renal disease were excluded. Soluble Flt-1 concentration was measured by specific immunoassay. Nonparametric techniques were used for statistical analysis.

RESULTS

1) The median maternal plasma, but not amniotic fluid, sFlt-1 concentration in patients who developed preeclampsia was significantly higher than in the control cases (maternal plasma: median 730 pg/mL, range 60-3375 pg/mL vs median 441 pg/mL, range 58-1959 pg/mL, P < .05; amniotic fluid: median 10,504 pg/mL, range 5253-38,023 pg/mL vs median 10,236 pg/mL, range 4326-87,684 pg/mL, P = .65). 2) The median plasma concentration of sFlt-1 was higher in cases of severe preeclampsia than in those with mild preeclampsia without reaching statistical significance (median 762 pg/mL, range 261-3309 pg/mL vs median 334 pg/mL, range 60-3375 pg/mL; P = .07). However, there was no significant difference in the median amniotic fluid sFlt-1 concentrations between patients with severe preeclampsia and those with mild preeclampsia (P = .45). 3) An elevated maternal plasma sFlt-1 concentration (higher than 700 pg/mL) is a risk factor for the development of preeclampsia (OR 3.9, 95% CI 1.7-8.6) and severe preeclampsia (OR 7.4, 95% CI 2.5-22.1) after genetic amniocentesis. 4) The median interval from amniocentesis to the diagnosis of preeclampsia in patients with maternal plasma sFlt-1 concentrations higher than 700 pg/mL was 117 days (range 19-154 days).

CONCLUSION

An elevated concentration of sFlt-1 in maternal plasma at the time of mid-trimester amniocentesis is a risk factor for the subsequent development of preeclampsia.

Placental system A transporter mRNA is not different in preeclampsia, normal pregnancy, or pregnancies with small-for-gestational-age infants

OBJECTIVE

System A amino acid transporter activity is reduced in placentas from small-for-gestational-age (SGA) compared to normal pregnancies. We compared the expression of the system A transporters between preeclamptic and control and between small-for-gestational-age and controls pregnancies.

METHODS

We used placental samples from 18 preeclamptic pregnancies matched with 17 normal pregnancies and from 16 SGA pregnancies matched with 15 different normal pregnancies. Using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) we quantified the mRNA for two system A subtype target genes ATA1 and ATA2 as well as beta-actin for normalization.

RESULTS

There was no significant difference of mRNA for ATA1 or ATA2 transporters between preeclamptic and their controls or SGA pregnancies and their controls.

CONCLUSIONS

Despite previous studies reporting reduced activity for system A transporters in small-for-gestational-age pregnancies, we found no difference in steady-state concentrations of the mRNA, of the system A transporters among preeclamptic, SGA, and normal control pregnancies. These results do not exclude differences in actual protein levels or activity of the amino acid transporters, which warrant further study.

Circulating oxidized low-density lipoprotein and paraoxonase activity in preeclampsia

Preeclampsia is one of the most frequent complications of pregnancy, however, little is known about its etiology. The objective of this study was to investigate the association of oxidized low-density lipoprotein (oxLDL) and paraoxonase (PON1) activity in women with either preeclampsia or normotensive (NT) pregnancy. The study groups included 41 pregnant women with preeclampsia and 33 normotensive pregnant women. In all patients maternal serum total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides (TGs) were measured using enzymatic methods. Serum PON1 activities and malondialdehyde (MDA) concentrations were measured by spectrophotometric methods, and oxLDL was measured by enzyme-linked immunoassay (ELISA). Serum concentrations of lipid parameters (TC, LDL, VLDL, and TGs) were significantly higher in preeclampsia compared with NT controls (p < 0.001, p < 0.05, p < 0.05, and p < 0.001, respectively). Serum concentrations of MDA and oxLDL were significantly higher, while PON1 activity was significantly lower in preeclampsia compared with NT controls (p < 0.001, p < 0.001, and p < 0.001, respectively). A positive correlation was detected between oxLDL and MDA (r = 0.876), and a negative correlation was detected between both MDA and oxLDL and PON1 (r = -0.837 and r = -0.759, respectively). Our data demonstrate that preeclampsia is associated with increased oxLDL and decreased PON1 activity. Elevated oxidative stress, oxLDL, dyslipidemia and decreased PON1 activities may cause vascular endothelial damage and contribute to the pathophysiology of preeclampsia.

Dietary intake of vitamin C and vitamin E and the development of hypertensive disorders of pregnancy

OBJECTIVES

To explore the relationship, if any, between dietary intake of the antioxidant vitamins C and E, and the development of pre-eclampsia and gestational hypertension.

STUDY DESIGN

A prospective cohort study of pregnant women attending the antenatal clinic of the Women's and Children's Hospital in Adelaide, Australia, was carried out between April and July 2001. Women completed a semi-quantitative 116-item food frequency questionnaire (FFQ). Women's medical records were viewed after birth to collect data on pregnancy outcomes. Relationships were explored through cross-tabulations, chi-square analysis, and adjustments were made for potential confounders using binary logistic regression.

RESULTS

A total of 299 women completed the FFQ. Median intake of vitamin C was 188 mg and for vitamin E was 6.74 mg. There was no relationship between the intake of vitamin C and hypertensive disorders of pregnancy. For vitamin E, being in the lowest quartile of intake, was associated with an increased risk of hypertensive disorders (RR 1.75, 95% CI 1.11-2.75, P = 0.02). This relationship was confirmed after adjusting for the confounding factors of maternal age and parity.

CONCLUSIONS

Little support was found for a relationship between dietary intake of vitamin C and the development of hypertensive disorders of pregnancy. Low vitamin E intake was associated with a significant increase in the risk of hypertensive disorders of pregnancy, even after adjustments were made for confounding factors. Further research is required to investigate whether supplementation above dietary intake of antioxidant vitamins influences the risk of hypertensive disorders of pregnancy.

Excessive stimulation of poly(ADP-ribosyl)ation contributes to endothelial dysfunction in pre-eclampsia

1. Pre-eclampsia is a serious pregnancy disorder associated with widespread activation of the maternal vascular endothelium. Recent evidence implicates a role for oxidative stress in the aetiology of this condition. 2. Reactive oxygen species, particularly superoxide anions, invokes endothelial cell activation through many pathways. Oxidant-induced cell injury triggers the activation of nuclear enzyme poly(ADP-ribose) polymerase (PARP) leading to endothelial dysfunction in various pathophysiological conditions (reperfusion, shock, diabetes). 3. We have studied whether the loss of endothelial function in pre-eclampsia is dependent on PARP activity. Endothelium-dependent responses of myometrial arteries were tested following exposure to either plasma from women with pre-eclampsia or normal pregnant women in the presence and absence of a novel potent inhibitor of PARP, PJ34. Additional effects of plasma and PJ34 inhibition were identified in microvascular endothelial cell cultures. 4. In myometrial arteries, PARP inhibition blocked the attenuation of endothelium-dependent responses following exposure to plasma from women with pre-eclampsia. In endothelial cell cultures, plasma from pre-eclamptics induced measurable oxidative stress and a concomitant increase in PARP activity and reduction in cellular ATP. Again, these biochemical changes were reversed by PJ34. 5. These results suggest that PARP activity plays a pathogenic role in the development of endothelial dysfunction in pre-eclampsia and promotes PARP inhibition as a potential therapy in this condition.

Calprotectin, a marker of inflammation, is elevated in the maternal but not in the fetal circulation in preeclampsia

OBJECTIVE

Preeclampsia is associated with excessive inflammatory response compared with normal pregnancy. Calprotectin is an inflammation marker not previously explored in preeclampsia.

STUDY DESIGN

Calprotectin in maternal and fetal plasma and amniotic fluid was investigated at cesarean delivery in normal pregnancies and preeclampsia. C-reactive protein (CRP) and plasminogen activator inhibitor type1 (PAI-1) were also analyzed.

RESULTS

Maternal median calprotectin, CRP, and PAI-1 concentrations were elevated in preeclampsia (1081 microg/L, 4.8 mg/L, and 51.0 U/mL) compared with control levels (552 microg/L, 3.8 mg/L, and 36.5 U/mL). In the umbilical vein, there were no differences between preeclampsia and controls regarding calprotectin and CRP levels. Maternal calprotectin concentrations correlate with CRP and PAI-1 values for the total study group, but a statistical significant correlation was not found in the preeclamptic group.

CONCLUSION

Calprotectin is elevated in the maternal circulation in preeclamptic pregnancies. We found no evidence of inflammatory response in the fetal circulation in preeclampsia.

Role of endothelin in mediating tumor necrosis factor-induced hypertension in pregnant rats

Hypertension during preeclampsia is associated with an increase in plasma levels of tumor necrosis factor (TNF)-alpha, a cytokine known to contribute to endothelial dysfunction. Recently, our laboratory reported that a 2-fold increase in plasma TNF-alpha produces hypertension in pregnant rats. Endothelin is also elevated in preeclampsia and endothelin synthesis is enhanced by TNF-alpha. The purpose of this study was to determine the role of endothlelin in mediating TNF-alpha-induced hypertension in pregnant rats. To achieve this goal, TNF-alpha (50 ng/d for 5 days) was infused into control pregnant rats and pregnant rats treated with an endothelin receptor A antagonist, ABT 627 (5 mg/kg per day for 5 days). At day 19 of gestation, arterial pressure was measured and aorta, kidneys, and placentas were harvested. Infusion of TNF-alpha into pregnant rats increased plasma concentration of TNF-alpha (13.5+/-0.8 to 28.0+/-3.7 pg/mL) and arterial pressure (101+/-2 to 122+/-1 mm Hg). The increase in arterial pressure was associated with an increase in preproendothelin mRNA expression in placenta, aorta, and kidneys measured by real-time polymerase chain reaction (PCR). Pretreatment with the endothelin receptor A antagonist completely abolished the blood pressure response to TNF-alpha in pregnant rats (105+/-1 versus 97+/-2 mm Hg). In sharp contrast, the ETA receptor antagonist had no effect on arterial pressure in normal pregnant rats (97+/-2 versus 101+/-2 mm Hg). Moreover, chronic infusion of TNF-alpha had no significant effect on arterial pressure or renal preproendothelin levels in virgin rats. These results suggest an important role for endothelin in mediating TNF-alpha-induced hypertension in pregnant rats.

PL74, a novel member of the transforming growth factor-beta superfamily, is overexpressed in preeclampsia and causes apoptosis in trophoblast cells

PL74, a novel member of the TGFbeta superfamily that has highest expression in placenta, is a multifunctional peptide that can induce differentiation, inhibit inflammatory stimulation of TNFalpha, and execute apoptosis after p53 overexpression and cytotoxic injury. To study its expression and function in placenta and preeclampsia, we first determined mRNA expression in nine normal and 10 preeclamptic placentas. PL74 mRNA was overexpressed by 57.3% in preeclampsia. Transfection of PL74 into term cytotrophoblasts resulted in increased apoptosis by terminal uridine deoxynucleotidyl nick end labeling labeling (control, 2.8 +/- 0.5%; PL74, 19.1 +/- 0.2%; P < 0.005). Addition of PL74 protein to HTR8/SVneo extravillous cytotrophoblast cells showed a dose-response (0-100 ng/ml) inhibition of [3H]thymidine uptake and increase in apoptosis shown by terminal uridine deoxynucleotidyl nick end labeling and histone-associated DNA fragment ELISA (control, 0.11 +/- 0.01 absorbance units; PL74, 0.21 +/- 0.01; P < 0.01). PL74 did not alter cytotrophoblast invasion using a Matrigel in vitro invasion assay. Cytokine regulation of PL74 mRNA expression in term cytotrophoblasts showed that epidermal growth factor and IFNgamma increased PL74 expression, but TGFbeta and TNFalpha had no effect. Transfection of antisense PL74 into term cytotrophoblast cells resulted in an inhibition of spontaneous differentiation at 2 and 24 h of culture (control vector, 30.8 +/- 3.1% and 26.4 +/- 1.2%; antisense PL74, 17.6 +/- 1.8%and 12.6 +/- 1.4% syncytial units, at 2 and 24 h respectively; P < 0.01). We conclude that PL74 is overexpressed in preeclampsia and may thus promote apoptosis of cytotrophoblasts at the expense of differentiation. PL74 secretion is induced by IFNgamma and may play a role in abnormal placental responses in preeclampsia.

Soluble Fms-like tyrosine kinase 1 and endothelial dysfunction in the pathogenesis of preeclampsia

Preeclampsia, a pregnancy-specific syndrome of hypertension and proteinuria, is characterized by defective placental vasculogenesis and widespread maternal endothelial dysfunction. Although the manifestations of preeclampsia are primarily maternal, the burden of morbidity and mortality is often on the neonate, since the only effective treatment-delivery of the fetus and placenta-often results in iatrogenic prematurity. In this review, we summarize recent advances in our understanding of the pathophysiology of preeclampsia, including normal and aberrant placental vascular development and evidence for endothelial dysfunction. We describe recent evidence that supports a novel mechanism in which a maladaptive shift in placental production of angiogenic factors such as soluble fms-like tyrosine kinase 1 (a circulating antiangiogenic protein) may play an important role in the pathogenesis of preeclampsia.

HO in pregnancy

The enzyme heme oxygenase (HO) has been implicated in several physiological functions throughout the body including control of vascular tone and regulation of the inflammatory and apoptotic cascades as well as contributing to the antioxidant capabilities in several organ systems. These various properties attributed to HO are carried out through the catalytic products of heme degradation, namely carbon monoxide (CO), biliverdin, and free iron (Fe2+). As the newly emerging roles of HO in normal organ function have come to light, researchers in several disciplines have assessed the role of this enzyme in various physiological and pathological changes taking place in the human body over a lifetime. Included in this new wave of interest is the involvement of HO, and its by-products, in the normal function of the vital organ of pregnancy, the placenta. In this review the role of HO, and its catalytic products, will be examined in the context of pregnancy. The different isoforms of the HO enzyme (HO-1, HO-2, HO-3) have been localized throughout placental tissue, and have been shown to be physiologically active. The HO protein and more specifically its catalytic by-products (CO, biliverdin, and Fe2+) have been postulated to be involved in the maintenance of uterine quiescence throughout gestation, regulation of hemodynamic control within the uterus and placenta, regulation of the apoptotic and inflammatory cascades in trophoblast cells, and the maintenance of a balance of the oxidant-antioxidant status within the placental tissues. The association between this enzyme system, and its above-noted roles throughout pregnancy, with the hypertensive disorder of pregnancy preeclampsia (PET), will also be examined. It is hypothesized that a decrease in HO expression and/or activity throughout gestation would be capable of initiating several pathological processes involved in the etiology of PET. This hypothesis has led to further discussion emphasizing the possibility of novel therapeutic designs targeting this enzyme system for the treatment of PET.

Reduced Uteroplacental Perfusion Alters Uterine Arcuate Artery Function in the Pregnant Sprague-Dawley Rat1

Evidence continues to implicate reduced placental perfusion as the cause of preeclampsia, initiating a sequence of events leading to altered vascular function and hypertension. The present study was designed to determine the influence of reduced uteroplacental perfusion pressure (RUPP) on the responsiveness of uterine arcuate resistance arteries. A condition of RUPP was surgically induced in pregnant Sprague-Dawley rats on Gestational Day 14. On Gestational Day 20, uterine arcuate arteries were mounted on a small-vessel wire myograph and challenged with incremental concentrations of vasoconstrictors and vasorelaxants for measurement of isometric tension. Compared to the sham-operated controls, uterine arteries from the RUPP group demonstrated an increased maximal tension in response to phenylephrine (P < 0.01); potassium chloride at 30 mM (P < 0.05), 60 mM (P < 0.01), and 120 mM (P < 0.01); and angiotensin II (P < 0.05). In arteries from the RUPP and sham-operated control groups, endothelium-dependent relaxation in response to acetylcholine (P < 0.05) and calcium ionophore (A23187; P < 0.05) was significantly reduced in the RUPP group compared to the sham-operated controls. Fetal growth indices, including litter size, fetal weight, and placental weight, were significantly reduced in the RUPP group compared to sham-operated controls, which is consistent with significant growth restriction. Data suggest that RUPP promotes hyperresponsiveness and impaired endothelium-dependent relaxation in uterine arcuate arteries, leading to intrauterine fetal growth restriction.

Pre-eclampsia

Pre-eclampsia is a major cause of maternal mortality (15-20% in developed countries) and morbidities (acute and long-term), perinatal deaths, preterm birth, and intrauterine growth restriction. Key findings support a causal or pathogenetic model of superficial placentation driven by immune maladaptation, with subsequently reduced concentrations of angiogenic growth factors and increased placental debris in the maternal circulation resulting in a (mainly hypertensive) maternal inflammatory response. The final phenotype, maternal pre-eclamptic syndrome, is further modulated by pre-existing maternal cardiovascular or metabolic fitness. Currently, women at risk are identified on the basis of epidemiological and clinical risk factors, but the diagnostic criteria of pre-eclampsia remain unclear, with no known biomarkers. Treatment is still prenatal care, timely diagnosis, proper management, and timely delivery. Many interventions to lengthen pregnancy (eg, treatment for mild hypertension, plasma-volume expansion, and corticosteroid use) have a poor evidence base. We review findings on the diagnosis, risk factors, and pathogenesis of pre-eclampsia and the present status of its prediction, prevention, and management.

The role of regular physical activity in preeclampsia prevention

Preeclampsia affects 2-7% of pregnancies and is a leading cause of maternal and fetal morbidity and mortality. Despite extensive study, the etiology of preeclampsia is poorly understood. Abnormal placental development, predisposing maternal constitutional factors, oxidative stress, immune maladaptation, and genetic susceptibility have all been hypothesized to contribute to the development of preeclampsia. Physical conditioning and preeclampsia have opposite effects on critical physiological functions. This suggests that regular prenatal exercise may prevent or oppose the progression of the disease. Epidemiologic studies show that occupational and leisure-time physical activity is associated with a reduced incidence of preeclampsia. We hypothesize that this protective effect results from one of more of the following mechanisms: 1) stimulation of placental growth and vascularity, 2) reduction of oxidative stress, and 3) exercise-induced reversal of maternal endothelial dysfunction. Future research should include prospective epidemiological case-control studies that accurately measure occupational and leisure-time physical activity. Controlled randomized clinical trials examining the effects of prenatal exercise on biochemical markers for endothelial dysfunction, placental dysfunction, and oxidative stress are also needed. If future research supports the idea that exercise effectively protects against preeclampsia, this would provide a low-cost intervention that could dramatically improve prenatal care for women at risk of this disease.

Placental malaria and pre-eclampsia through the looking glass backwards?

Placental malaria and pre-eclampsia occur frequently in women in developing countries and are leading causes of fetal growth restriction. Reduced placental perfusion, loss of placental integrity and endothelial cell dysfunction are characteristics of both conditions, and several common factors can be implicated in their causation as well as leading to a cascade of responses with pathophysiological effects. Discrimination between risk factors which result in a loss of endothelial integrity from pathogenic factors which occur as a consequence of this is essential for understanding the potential influence of malaria on pre-eclampsia. This article summarises the evidence linking the two conditions in relation to their epidemiological, immunological, haematological and biochemical characteristics as well as the pathological similarities and differences related to placental structure and function. The potential similar role for nitric oxide synthase involvement in both placental malaria and pre-eclampsia is considered. Several research implications are highlighted which follow from this analysis. We consider that there is no clear dividing line between pathogenic mechanisms related to both conditions, a better understanding of which should be of benefit to millions of women in developing countries.

Soluble factors released by placental villous tissue: Interleukin-1 is a potential mediator of endothelial dysfunction

OBJECTIVE

The purpose of this study was to analyze the potential of placental-conditioned medium to activate endothelial cells in vitro and to identify the placental factors that mediate this effect.

STUDY DESIGN

Placental-conditioned medium was generated by the culturing of normal term placental villous explants for up to 48 hours. Human umbilical vein endothelial cells were exposed to the conditioned media, and cellular proliferation, viability, and activation were investigated.

RESULTS

The proliferation of endothelial cells that were exposed to 20% placental-conditioned medium was reduced by 25%, but their survival was not compromised. Conditioned medium also up-regulated the expression of E-selectin and stimulated the release of soluble intercellular adhesion molecule-1 and the secretion of interleukin-6. Treatment with interleukin-1 receptor antagonist, but not with an anti-tumor necrosis factor-alpha neutralizing antibody, blocked the release of soluble intercellular adhesion molecule-1 and interleukin-6.

CONCLUSION

Placentally derived interleukin-1 may be 1 of the potential mediators of the maternal inflammatory response that is observed in late pregnancy.

Concentrations of pentosidine, an advanced glycation end-product, in umbilical cord blood

Advanced glycation end-products (AGEs) are formed over several weeks to months by non-enzymatic glycation and oxidation ("glycoxidation") reactions between carbohydrate-derived carbonyl groups and protein amino groups, known as the Maillard reaction. Pentosidine is one of the best-characterized AGEs and is accepted as a satisfactory marker for glycoxidation in vivo. The present study was intended to measure pentosidine concentrations in umbilical cord blood from newborns with various gestational ages using our recently established high-performance liquid chromatography method [Tsukahara, H. et al. (2003) Pediatr. Res. 54, 419-424]. Our study demonstrates, for the first time, that pentosidine is detected in most of the umbilical blood samples. This study also shows that the umbilical blood concentrations of pentosidine are considerably lower than normal adult values, but that they increase with gestation progression and fetal growth. Umbilical pentosidine concentrations were significantly elevated in newborns of mothers with preeclampsia compared to those of mothers without preeclampsia. We conclude that accumulation of AGEs and oxidative stress occurs in fetal tissues and organs in utero at the early stage of human life and that their accumulation is augmented in the maternal preeclampsic condition.

Direct placental effects of cigarette smoke protect women from pre-eclampsia: the specific roles of carbon monoxide and antioxidant systems in the placenta

Pre-eclampsia is a hypertensive disorder of pregnancy characterized by shallow placentation, inadequate placental perfusion, localized placental oxidative stress, a heightened maternal inflammatory response and subsequent maternal endothelial dysfunction. This pathophysiology leads to an increase in maternal blood pressure, edema and proteinurea. Interestingly, women who smoke cigarettes throughout pregnancy are at a 33% reduced risk of developing this disorder. The exact mechanisms through which cigarette smoke reduces the risk of pre-eclampsia are not yet understood. We propose that cigarette smoke reduces the risk of developing pre-eclampsia via direct placental effects. In this review we will address, and provide evidence for, our specific hypotheses that: (a) CO increases trophoblast invasion and spiral arteriole remodeling; (b) CO decreases a localized inflammatory response at the level of the decidua; (c) CO increases utero-placental, intra-placental and feto-placental blood flow; (d) CO decreases hypoxia-induced apoptosis of the syncitiotrophoblast layer; (e) CO activates hemoproteins involved in normal endothelial functioning normally acted upon by NO; (f) compound(s) within cigarette smoke result in upregulation of antioxidant systems within the placenta. These various mechanisms of action must be further examined as they may provide valuable keys to novel therapeutic design in the realm of pre-eclampsia research.

Postpartum Preeclampsia Management With Furosemide: A Randomized Clinical Trial

OBJECTIVE

This investigation was undertaken to estimate whether a brief postpartum course of furosemide for patients with preeclampsia benefits recovery and shortens hospitalization by enhancing diuresis, lessening severe hypertension, and reducing the need for antihypertensive therapy.

METHODS

Two hundred sixty-four patients with preeclampsia were enrolled. After spontaneous onset of postpartum diuresis and discontinuation of intravenous magnesium sulfate, patients were randomly assigned to receive either no therapy or 20 mg oral furosemide daily for 5 days with oral potassium supplementation. Patient outcomes were compared between treatment groups with regard to classification of hypertensive disease.

RESULTS

Only postpartum patients with severe preeclampsia (n = 70) who received furosemide compared with controls had significantly lower systolic blood pressure by postpartum day 2 (142 +/- 13 mm Hg compared with 153 +/- 19 mm Hg, P < .004) and required less antihypertensive therapy during hospitalization (14% compared with 26%, P = .371) and at discharge (6% compared with 26%, P = .045). No benefit was shown for patients with mild preeclampsia (n = 169) or superimposed preeclampsia (n = 25). Neither length of hospitalization nor frequency of delayed postpartum complications was positively affected by the intervention.

CONCLUSION

Brief postpartum furosemide therapy for patients with severe preeclampsia seems to enhance recovery by normalizing blood pressure more rapidly and reducing the need for antihypertensive therapy. Shortening of hospitalization and reduction of delayed postpartum complications were not benefitted.

Emerging technologies for the identification of therapeutic targets for the management of pre-eclampsia

Pre-eclampsia is a common and serious complication of pregnancy characterised by hypertension and proteinuria. Genetic and environmental factors influence the occurrence and progression of the disease. Emerging experimental systems and increasingly specific analytical methods for the study of differences between normal and pre-eclamptic placentae are close to identifying specific indicators of disease, which may allow early diagnosis and intervention and reveal targets against which therapeutic agents can be developed.

Parathyroid Hormone-Related Protein in Preeclampsia: A Linkage Between Maternal and Fetal Failures

Preeclampsia is a disorder associated with pregnancy that affects both the mother and the fetus. Typical features of the disease are maternal hypertension, proteinuria, and edema as well as fetal growth retardation. Although the etiological details are still being debated, a consensus exists that the starting point is deficient placentation in the first half of pregnancy. The crucial early steps are reduced trophoblast invasiveness and enhanced apoptotic death. In the present review, we demonstrate that parathyroid hormone-related protein is involved not only in the maternal and fetal failures but also in the etiological aspects of the disease. We hypothesize that reduced local production of the peptide is a major causative event.