Pathophysiology of hypertension during preeclampsia linking placental ischemia with endothelial dysfunction

First-trimester maternal serum tumor necrosis factor receptor-1 and pre-eclampsia

OBJECTIVES

To examine whether the maternal serum concentration of the soluble receptor-1 of tumor necrosis factor-alpha (TNF-R1) at 11-13 weeks of gestation in pregnancies that subsequently develop pre-eclampsia is different from that in women without this complication.

METHODS

The concentration of TNF-R1 at 11 + 0 to 13 + 6 weeks was measured in samples from 128 cases that subsequently developed pre-eclampsia and 569 controls with no pregnancy complications. TNF-R1 and uterine artery pulsatility index (UtA-PI) values were expressed as multiples of the median (MoM) adjusted for maternal factors. The distributions of log TNF-R1 MoM and log UtA-PI MoM in the control and pre-eclampsia groups were compared. Logistic regression analysis was used to determine whether a significant contribution is provided by maternal factors, TNF-R1 and UtA-PI in predicting pre-eclampsia. The performance of screening was determined by analysis of receiver-operating characteristics curves.

RESULTS

Median TNF-R1 and UtA-PI were significantly higher in the pre-eclampsia group (TNF-R1, 1.062 MoM; UtA-PI, 1.301 MoM) than in the control group (TNF-R1, 0.996 MoM; UtA-PI, 1.037 MoM). There was no significant association between TNF-R1 and gestational age at delivery, birth weight percentile or UtA-PI. Logistic regression analysis demonstrated significant contributions to the detection of pre-eclampsia from maternal factors and UtA-PI but not from TNF-R1.

CONCLUSIONS

In pregnancies developing pre-eclampsia the maternal serum TNF-R1 concentration at 11-13 weeks of gestation is increased, but the level of TNF-R1 is not associated with the degree of impairment in placental perfusion or the severity of pre-eclampsia. Measurement of serum TNF-R1 does not improve the prediction of pre-eclampsia provided by screening based on a combination of maternal factors and UtA-PI.

Cardiovascular sequelae of preeclampsia/eclampsia: a systematic review and meta-analyses

BACKGROUND

Preeclampsia affects 3% to 5% of gestations and eclampsia 0.05% to 0.93%, but their subsequent cardiovascular sequelae are unclear. The aim of this study was to determine if women with a history of preeclampsia/eclampsia are at increased risk of long-term cardiovascular sequelae.

METHODS

From Medline and Embase searches, we included case-control and cohort studies that examined cardiac, cerebrovascular or peripheral arterial disease, or cardiovascular mortality>6 weeks postpartum, in women with and without a history of preeclampsia/eclampsia and that controlled for or matched for confounders. Two independent reviewers determined study eligibility and extracted data.

RESULTS

Five case-control and 10 cohort studies met eligibility criteria, with a total of 116,175 women with and 2,259,576 women without preeclampsia/eclampsia. Most studies focused on women<56 years of age. Relative to women with uncomplicated pregnancies, women with a history of preeclampsia/eclampsia had an increased risk of subsequent cardiac disease in both the case-control studies (odds ratio 2.47, 95% CI 1.22-5.01) and the cohort studies (relative risk [RR] 2.33, 1.95-2.78), as well as an increased risk of cerebrovascular disease (RR 2.03, 1.54-2.67), peripheral arterial disease (RR 1.87, 0.94-3.73), and cardiovascular mortality (RR 2.29, 1.73-3.04). Meta-regression revealed a graded relationship between the severity of preeclampsia/eclampsia and the risk of cardiac disease (mild: RR 2.00, 1.83-2.19, moderate: RR 2.99, 2.51-3.58, severe: RR 5.36, 3.96-7.27, P<.0001).

CONCLUSIONS

Women with a history of preeclampsia/eclampsia have approximately double the risk of early cardiac, cerebrovascular, and peripheral arterial disease, and cardiovascular mortality. Further research is needed to determine the mechanisms underlying these associations and to identify effective prevention strategies.

Pathophysiology of hypertension in response to placental ischemia during pregnancy: a central role for endothelin?

BACKGROUND

Preeclampsia is new-onset hypertension with proteinuria during pregnancy. The initiating event in preeclampsia has been postulated to involve reduced placental perfusion, which leads to widespread dysfunction of the maternal vascular endothelium.

OBJECTIVE

The main objective of this brief review was to highlight some of the recent advances in our understanding of the mechanisms whereby the endothelin (ET) system, via ET type A (ETA) receptor activation, modulates blood pressure in preeclamptic women and in animal models of pregnancy-related hypertension.

METHODS

This review focused on the role of ET and tumor necrosis factor-alpha (TNF-alpha) in preeclampsia, with emphasis on the pathophysiology of hypertension in response to placental ischemia in animal models of pregnancy. Relevant published data were identified by searching PubMed and supplemented with contributions from our laboratory.

RESULTS

Studies in preeclamptic women indicate that their hypertension is associated with increases in ET synthesis. Recent studies in pregnant rats indicate that the ET system is activated in response to reductions in uterine perfusion pressure and to chronic elevations in serum TNF-alpha concentrations. In these 2 animal models, the findings also suggest that ET A receptor activation may play a role in mediating hypertension.

CONCLUSIONS

Although recent studies in animal models implicate an important role for the ET system in preeclampsia, the usefulness of selective ET A receptor antagonists for the treatment of hypertension in women with preeclampsia remains unclear. This important question will not be answered until well-controlled clinical studies using specific ET A receptor antagonists are conducted for women with preeclampsia.

Angiotensin receptor agonistic autoantibodies induce pre-eclampsia in pregnant mice

Pre-eclampsia affects approximately 5% of pregnancies and remains a leading cause of maternal and neonatal mortality and morbidity in the United States and the world. The clinical hallmarks of this maternal disorder include hypertension, proteinuria, endothelial dysfunction and placental defects. Advanced-stage clinical symptoms include cerebral hemorrhage, renal failure and the HELLP (hemolysis, elevated liver enzymes and low platelets) syndrome. An effective treatment of pre-eclampsia is unavailable owing to the poor understanding of the pathogenesis of the disease. Numerous recent studies have shown that women with pre-eclampsia possess autoantibodies, termed AT(1)-AAs, that bind and activate the angiotensin II receptor type 1a (AT(1) receptor). We show here that key features of pre-eclampsia, including hypertension, proteinuria, glomerular endotheliosis (a classical renal lesion of pre-eclampsia), placental abnormalities and small fetus size appeared in pregnant mice after injection with either total IgG or affinity-purified AT(1)-AAs from women with pre-eclampsia. These features were prevented by co-injection with losartan, an AT(1) receptor antagonist, or by an antibody neutralizing seven-amino-acid epitope peptide. Thus, our studies indicate that pre-eclampsia may be a pregnancy-induced autoimmune disease in which key features of the disease result from autoantibody-induced angiotensin receptor activation. This hypothesis has obvious implications regarding pre-eclampsia screening, diagnosis and therapy.

Analytical approaches to detect maternal/fetal genotype incompatibilities that increase risk of pre-eclampsia

BACKGROUND

In utero interactions between incompatible maternal and fetal genotypes are a potential mechanism for the onset or progression of pregnancy related diseases such as pre-eclampsia (PE). However, the optimal analytical approach and study design for evaluating incompatible maternal/offspring genotype combinations is unclear.

METHODS

Using simulation, we estimated the type I error and power of incompatible maternal/offspring genotype models for two analytical approaches: logistic regression used with case-control mother/offspring pairs and the log-linear regression used with case-parent triads. We evaluated a real dataset consisting of maternal/offspring pairs with and without PE for incompatibility effects using the optimal analysis based on the results of the simulation study.

RESULTS

We identified a single coding scheme for the incompatibility effect that was equally or more powerful than all of the alternative analysis models evaluated, regardless of the true underlying model for the incompatibility effect. In addition, the log-linear regression was more powerful than the logistic regression when the heritability was low, and more robust to adjustment for maternal or fetal effects. For the PE data, this analysis revealed three genes, lymphotoxin alpha (LTA), von Willebrand factor (VWF), and alpha 2 chain of type IV collagen (COL4A2) with possible incompatibility effects.

CONCLUSION

The incompatibility model should be evaluated for complications of pregnancy, such as PE, where the genotypes of two individuals may contribute to the presence of disease.

Use of antihypertensive drugs during pregnancy and lactation

The decision to treat elevated arterial pressure in pregnancy depends on the risk and benefits imposed on the mother and the fetus. Treatment for mild-to-moderate hypertension during pregnancy may not reduce maternal or fetal risk. Severe hypertension, on the other hand, should be treated to decrease maternal risk. Methyldopa and beta-adrenoceptor antagonists have been used most extensively. In acute severe hypertension, intravenous labetalol or oral nifedipine are reasonable choices.

Eclampsia: a neurological perspective

Eclampsia is a poorly understood disorder characterized by seizures or unexplained coma in setting of gestational hypertension. Its neurological manifestations are varied and are an important cause of the morbidity and mortality associated. We present a comprehensive prospective study of forty women recruited over four years describing neurological symptoms and signs, neuroimaging and laboratory studies as well as prognosis including 3-6 months follow-up. The seizures occurred in the postpartum period in majority of women (55%), while 45% had seizures before labor, and the rest (5%) during labor. Interestingly, one third of the women suffered their first seizures more than 48 h postpartum (late postpartum eclampsia). A sizable minority suffered more than one seizure and some had documented partial seizures. Headache preceded seizures by more than a day and was described as throbbing or pounding pain by most. The visual symptoms in decreasing frequency were blurring, blindness, scotoma and visual processing deficits. The most common finding during the neurological exam was memory deficits, followed by increased deep tendon reflexes (asymmetric in some), visual perception deficits, visual information processing deficits, altered mental status and cranial nerve deficits. Intracranial or intraspinal pressure when examined was elevated. Among neuroimaging studies, MRI was more sensitive compared to CT scan. The MRI abnormalities included both white as well as gray matter and the most common location of abnormalities was high frontal/parietal lobe. The laboratory studies revealed proteinuria in majority, but not in all. The liver function tests were abnormal in many, while few patients had HELLP syndrome. The neurological deficits resolved by the time of discharge in all. At follow-up, some patients developed new neurological problems such as recurrent headaches or seizures.

Preeclamptic sera induce nephrin shedding from podocytes through endothelin-1 release by endothelial glomerular cells

In preeclampsia (PE), proteinuria has been associated with a reduced expression of nephrin by podocytes. In the present study, we investigated in vitro on human cultured podocytes the mechanism responsible for nephrin loss in PE. Sera from patients with PE did not directly downregulate the expression of nephrin. In contrast, conditioned medium obtained from glomerular endothelial cells incubated with PE sera induced loss of nephrin and synaptopodin, but not of podocin, from podocytes. Nephrin loss was related to a rapid shedding of the protein from the cell surface due to cleavage of its extracellular domain by proteases and to cytoskeleton redistribution. The absence of nephrin mRNA downregulation together with nephrin reexpression within 24 h confirm that the loss of nephrin was not related to a reduced synthesis. Studies with an endothelin-1 (ET-1) receptor antagonist that abrogated the loss of nephrin triggered by glomerular endothelial conditioned medium of PE sera indicated that ET-1 was the main effector of nephrin loss. Indeed, ET-1 was synthesized and released from glomerular endothelial cells when incubated with PE sera, and recombinant ET-1 triggered nephrin shedding from podocytes. Moreover, VEGF blockade induced ET-1 release from endothelial cells, and in turn the conditioned medium obtained triggered nephrin loss. In conclusion, the present study identifies a potential mechanism of nephrin loss in PE that may link endothelial injury with enhanced glomerular permeability.

Angiotensin receptors, autoimmunity, and preeclampsia

Preeclampsia is a pregnancy-induced hypertensive disorder that causes substantial maternal and fetal morbidity and mortality. Despite being a leading cause of maternal death and a major contributor to maternal and perinatal morbidity, the mechanisms responsible for the pathogenesis of preeclampsia are poorly understood. Recent studies indicate that women with preeclampsia have autoantibodies that activate the angiotensin receptor, AT1, and that autoantibody-mediated receptor activation contributes to pathophysiology associated with preeclampsia. The research reviewed here raises the intriguing possibility that preeclampsia may be a pregnancy-induced autoimmune disease.

Effects of magnesium sulphate on placental expression of endothelin 1 and its receptors in preeclampsia

OBJECTIVES

To investigate the effects of magnesium sulphate (MgSO(4)) on placental expression of endothelin 1 (ET-1) and its receptors in preeclampsia (PE).

DESIGN AND METHODS

Placentas were obtained from 10 normotensive (NT group) and 18 moderate preeclamptic (PE group) women. Among the PE group, 10 patients were treated with 0.9% NaCl solution (PES) and 8 women received MgSO(4) (PEMgSO(4)). Placental mRNAs of ET-1, ET-1(A) receptor (ET-1(A)R) and ET-1(B) receptor (ET-1(B)R) were evaluated by Northern blot and quantified using densitometry.

RESULTS

Placental ET-1(B)R expression was lower (P<0.05) in the PES group without significant changes in the mRNAs of ET-1 and ET-1(A)R when compared with the NT group. MgSO(4) treatment was associated with decreased ET-1 and increased ET-1(B)R (P<0.05) expression, without significant changes in ET-1(A)R.

CONCLUSIONS

The results of the present study showed that moderate PE is associated with low placental expression of ET-1(B)R, and MgSO(4) treatment resulted in placental expression changes of the ET-1/receptors system.

Impact of maternal angiotensinogen M235T polymorphism and angiotensin-converting enzyme insertion/deletion polymorphism on blood pressure, protein excretion and fetal outcome in pregnancy

OBJECTIVE

To test the hypothesis that genetically determined alterations of the renin-angiotensin system are associated with hypertensive disorders in pregnancy.

METHODS

A genetic association study was conducted at the obstetrics department of the Charité university hospital, Berlin, Germany. A total of 1068 Caucasian women were consecutively included after delivery and genotyped for the angiotensinogen M235T polymorphism and the angiotensin-converting enzyme (ACE) insertion/deletion polymorphism.

RESULTS

Women homozygous for the angiotensinogen T allele have significantly elevated mean systolic and diastolic blood pressures in the third trimester (118.4 +/- 1.1/71.5 +/- 0.7 versus 116.9 +/- 0.3/70.4 +/- 0.2 mmHg, n = 128 versus 940; P < 0.05). This finding is especially pronounced in the subgroup of primigravid women. The ACE polymorphism is not associated with blood pressure during pregnancy. None of the polymorphisms is associated with urinary protein excretion or oedema during pregnancy. Maternal polymorphisms do not influence fetal growth and birth weight. There is, however, an interesting trend towards an increased incidence of circulatory system malformations in newborns carrying alleles that are known to be associated with decreased intrinsic renin-angiotensin system activity.

CONCLUSION

We demonstrate for the first time in a large Caucasian population that a common maternal polymorphism of the angiotensinogen gene is related to a blood pressure increase during pregnancy. The angiotensinogen M235T polymorphism might contribute to the multifactorial pathogenesis of gestational hypertension and pre-eclampsia.

Suramin-Restricted Blood Volume in the Placenta of Normal and Diabetic Rats is Normalized by Vitamin E Treatment

Previously maternal and fetal alterations resembling human pre-eclampsia were induced in pregnant rats by injections of the angiogenesis inhibitor Suramin. These alterations were aggravated by maternal diabetes and partly rectified by vitamin E supplementation. In the present study we evaluated the morphology of placentae and kidneys in this model. Non-diabetic and streptozotocin-induced diabetic pregnant rats of two rat strains (U and H) were treated with Suramin or saline, and given standard or vitamin E-enriched food. On gestational day 20 one placenta and the left kidney of the mother were collected for morphological and stereological analysis. In the placental trophospongium Suramin treatment caused cysts, which were further enhanced by maternal diabetes. Vitamin E treatment had no effect on the vacuolization. In the placental labyrinth of the non-diabetic rats Suramin treatment restricted maternal placental blood volume and increased the interface between maternal and fetal circulation. These changes were reversed by vitamin E treatment. Diabetes increased slightly the interface between the circulations in both rat strains. Suramin treatment decreased the interface, and vitamin E further decreased the interface in the diabetic U rats, whereas neither treatment affected the maternal-fetal interface in the diabetic H rats. The kidneys of Suramin-treated and diabetic rats were heavier compared to controls. Suramin treatment and maternal diabetes damaged renal glomeruli to a similar extent. Vitamin E treatment diminished the Suramin- and diabetes-induced glomerular damage in U rats, but not in H rats. The average cell count per glomerulus was decreased by Suramin in the U rats. Vitamin E treatment did not affect cell number per glomerulus in any group. We conclude that Suramin-injected pregnant rats constitute a valid animal model for placental dysfunction and pre-eclampsia, also from the histological perspective. The present work supports the notion that one important effect of untreated maternal diabetes may be impaired placentation, leading to oxidative stress, morphological damage, and compromised placental function.

Alpha 2,6-sialyltransferase I expression in the placenta of patients with preeclampsia

BACKGROUND

The expression of sialyl-glycoconjugates changes during development, differentiation and oncogenic transformation, tumor invasion and metastasis. Similarly, in the early stage of pregnancy, trophoblast cells have to undergo adhesion, invasion, and proliferation to develop a healthy placenta; the cytobiologic behavior is similar to tumor growth and invasion. Inadequate trophoblast invasion to the spiral artery in the 2nd trimester of pregnancy was believed to be correlated with pregnancy complications, including preeclampsia.

METHODS

Alterations in alpha2,6-sialyltransferase I (ST6Gal I) mRNA in the placental tissues of women with preeclampsia (n=20) and without preeclampsia (n=20 used as a control) were examined by semiquantitative reverse transcription-polymerase chain reaction and real-time quantitative reverse transcription-polymerase chain reaction. The transcription regulators of ST6Gal I including a "constitutive" promoter (Y + Z form), "hepatic" promoter (H form), and lymphoblastic promoter (X form) were investigated. The enzyme activity of ST6Gal I was also examined.

RESULTS

Both mRNA expression and enzyme activity of ST6Gal I did not show a significant difference in the placental tissues of the women of both groups. The transcription regulators of ST6Gal I, including the Y+Z form and the H form, also failed to show any difference. The X form, seldom detected in the study, was excluded from analysis.

CONCLUSION

Our results suggested that ST6Gal I was not involved in the pathogenesis of the preeclampsia.

Pregnancy prevents hypertensive remodeling and decreases myogenic reactivity in posterior cerebral arteries from Dahl salt-sensitive rats: a role in eclampsia?

Previous studies have demonstrated that pregnancy prevents protective hypertension-induced remodeling of cerebral arteries using nitric oxide synthase (NOS) inhibition to raise mean arterial pressure (MAP). In the present study, we investigated whether this effect of pregnancy was specific to NOS inhibition by using the Dahl salt-sensitive (SS) rat as a model of hypertension. Nonpregnant ( n = 16) and late-pregnant ( n = 17) Dahl SS rats were fed either a high-salt diet (8% NaCl) to raise blood pressure or a low-salt diet (<0.7% NaCl). Third-order posterior cerebral arteries were isolated and pressurized in an arteriograph chamber to measure active responses to pressure and passive remodeling. Several vessels from each group were stained for protein gene product 9.5 to determine perivascular nerve density. Blood pressure was elevated in both groups on high salt. The elevated MAP was associated with significantly smaller active and passive diameters ( P < 0.05) and inward remodeling in the nonpregnant hypertensive group only. Whereas no structural changes were observed in the late-pregnant hypertensive animals, both late-pregnant groups had diminished myogenic reactivity ( P < 0.05). Nerve density in both the late-pregnant groups was significantly greater when compared with the nonpregnant groups, suggesting that pregnancy has a trophic influence on perivascular innervation of the posterior cerebral artery. However, hypertension lowered the nerve density in both nonpregnant and late-pregnant animals. It therefore appears that pregnancy has an overall effect to prevent hypertension-induced remodeling regardless of the mode of hypertension. This effect may predispose the brain to autoregulatory breakthrough, hyperperfusion, and eclampsia when MAP is elevated.

Endothelin, the kidney, and hypertension

The kidneys play a central role in the long-term regulation of blood pressure and in the pathogenesis of hypertension. A common defect that has been found in all forms of hypertension examined to date is a hypertensive shift in the pressure-natriuresis relationship. A major objective of this brief review is to highlight some of the recent advances in our understanding of the mechanisms whereby the renal endothelin system, via endothelin type A- and endothelin type B-receptor activation, modulates renal pressure-natriuresis and blood pressure regulation under normal physiologic conditions and in certain forms of hypertension.

Organ systems dependent on nitric oxide and the potential for nitric oxide-targeted therapies in related diseases

Nitric oxide (NO) is a universal messenger molecule that plays diverse and essential physiologic roles in multiple organ systems, including the vasculature, bone, muscle, heart, kidney, liver, and central nervous system. NO is produced by 3 known isoforms-endothelial, neuronal, and inducible NO synthase-each of which perform distinct functions. Impairment of NO bioactivity may be an important factor in the pathogenesis of a wide range of conditions, including preeclampsia, osteoporosis, nephropathy, liver disease, and neurodegenerative diseases. Although increased levels of NO synthase or NO bioactivity have been associated with some of these disease states, research increasingly suggests that preservation or promotion of normal NO bioactivity may be beneficial in reducing the risks and perhaps reversing the underlying pathophysiology. Based on this rationale, studies investigating the use of NO-donating or NO-promoting agents in some of these diseases have produced positive results, at least to some degree, in either animal or human studies. Further investigation of NO-targeted therapies in these diverse diseases is clearly mandated.

Immunological exposures in Norwegian agriculture and pre-eclampsia

Immune system perturbations are involved in pre-eclampsia pathophysiology. We hypothesised that immunomodulating substances, such as mycotoxins, endotoxins or pesticides, affect pre-eclampsia risk. Associations between indicators of immunomodulating exposures in agriculture and pre-eclampsia are reported. In a Norwegian family cohort based on participants in agricultural censuses conducted by Statistics Norway 1969-89, 183 313 pregnancies to farmers were identified in the Medical Birth Registry of Norway. Cases notified as pre-eclampsia as well as pregnancies indicated by hypertension in combination with proteinuria were included. Data on farm production and meteorologically based fungal forecasts 1973-90 (a marker of temperate and humid climatic conditions known to favour fungal growth and mycotoxin formation in grain) were obtained and allocated to each farm. Pre-eclampsia prevalence rates were studied in strata of exposure indicators using Poisson regression models. Adjusted rate ratios (RR) and 95% confidence intervals [CI] were computed. We identified 4912 cases, equivalent to 26.8 pre-eclampsia cases per 1000 pregnancies [95% CI 26.1, 27.6]. Pre-eclampsia showed moderate associations with animal farming, RR 1.14, [95% CI 1.07, 1.22] and moderate negative associations with grain production, RR 0.93, [95% CI 0.86, 1.01], and two or more fungal forecasts appearing in any year 1973-90, RR 0.90 [95% CI 0.84, 0.97], using no years with two or more forecasts as reference. Exposure to immunomodulating substances as indicated by grain farming, animal farming and fungal warnings could possibly have moderate effects on pre-eclampsia risk, thus supporting the study hypothesis. The use of exposure indicators as surrogates for real exposures may introduce a non-differential misclassification of the exposure that would attenuate any true exposure-outcome association. The use of exposure proxies warrants that inferences from the study should be made with caution.

Carbon monoxide inhibits hypoxia/reoxygenation-induced apoptosis and secondary necrosis in syncytiotrophoblast

Pre-eclampsia, a hypertensive disorder of pregnancy, affects 5 to 7% of pregnancies. Oxidative stress-induced placental injury and subsequent release of placental debris into the maternal circulation are key pathogenic events in the progression of pre-eclampsia. Women who smoke cigarettes throughout pregnancy are 33% less likely to develop this disorder than nonsmoking women. We postulated that elevated carbon monoxide concentrations in serum of smoking women inhibits apoptosis and debris shedding of trophoblast cells exposed to ischemia-reperfusion injury because carbon monoxide has cytoprotective effects on endothelial and smooth muscle cells in culture. This may be responsible for the reduced risk of pre-eclampsia in smoking women. To assess the cytoprotective properties of carbon monoxide within placental tissue, carbon monoxide treatments were administered to in vitro hypoxia/reoxygenation-insulted villous explants cultured from term human placenta. Induction of apoptosis was assessed using molecular and morphological approaches. Placental villous explants treated with carbon monoxide demonstrated 60% less hypoxia/reoxygenation-induced apoptosis in the differentiated syncytiotrophoblast layer compared with untreated explants undergoing a similar insult. In addition, retention of intact syncytial membranes was observed in carbon monoxide-treated explants. These observations indicate that carbon monoxide has potent antiapoptotic properties within human placenta and may hold therapeutic potential in the treatment of pre-eclampsia.

Hypoxia and Reoxygenation: a Possible Mechanism for Placental Oxidative Stress in Preeclampsia

Preeclampsia is a human pregnancy-specific disorder that is diagnosed by the new appearance of hypertension and proteinuria after 20 weeks' gestation. It is a leading cause of perinatal morbidity and mortality, and the only intervention that effectively reverses the syndrome is delivery. Oxidative stress of the placenta is considered to be a key intermediary step in the pathogenesis of preeclampsia, but the cause for the stress remains unknown. Hypoxia-reoxygenation (H/R) injury, as a result of intermittent placental perfusion secondary to deficient trophoblast invasion of the endometrial arteries, is a possible mechanism. In this review, we present evidence to show that there is a plausible basis from which to assume that blood flow in the intervillous space will be intermittent in all normal pregnancies. The intermittency will be exacerbated by impaired conversion of the spiral arteries, or by the presence of atherotic changes that reduce their caliber as seen in preeclampsia. Placental oxidative stress can be the consequences of fluctuations in oxygen concentrations after H/R through the actions of reactive oxygen species. On this basis, there will be a complete spectrum of placental changes among the normal, the late onset and the early onset preeclamptic states. Viewing the syndrome as a continuum of H/R insults provides new insight into the pathophysiology of pregnancy that will hope fully lead to improved clinical interventions.

Brief overview of maternal triglycerides as a risk factor for pre-eclampsia

BACKGROUND

Features of the metabolic syndrome-maternal obesity, diabetes mellitus and chronic hypertension-are risk factors for pre-eclampsia.

OBJECTIVES

To determine the risk of pre-eclampsia in the presence of maternal hypertriglyceridemia, another major element of the metabolic syndrome.

SEARCH STRATEGY

Two investigators independently searched PubMed and Embase databases from 1980 to December 2004 for relevant studies. The terms preeclampsia, eclampsia, pregnancy-induced hypertension or toxemia were combined with dyslipidemia, hyperlipidemia, hypertriglyceridemia, lipids, cholesterol, triglycerides (TG) or lipoprotein.

SELECTION CRITERIA

We included case-control and cohort studies published in English that included at least 20 women with pre-eclampsia and that sampled serum or plasma TG at any time before, during or after pregnancy.

DATA COLLECTION AND ANALYSIS

Mean maternal TG concentrations were compared between cases and controls within each study. The odds ratio of pre-eclampsia was calculated by comparing the risk of pre-eclampsia among women in each higher TG concentration category with that in the lowest reference category.

MAIN RESULTS

A total of 19 case-control and 3 prospective cohort studies were included. In 14 studies, the mean TG concentration was significantly higher among pre-eclamptic cases than among unaffected controls; in seven other studies, there was a nonsignificant trend in the same direction. The risk of pre-eclampsia typically doubled with each increasing TG category. In the four studies that adjusted for potential confounders, such as maternal age, parity and body mass index, there was about a four-fold higher risk of pre-eclampsia in the highest relative to the lowest TG category.

AUTHOR'S CONCLUSIONS

There exists a consistent positive association between elevated maternal TG and the risk of pre-eclampsia. Given that maternal hypertriglyceridemia is a common feature of the metabolic syndrome, interventional studies are needed to determine whether pre-pregnancy weight reduction and dietary modification can lower the risk of pre-eclampsia.

Some thoughts on the vasculopathy of women with ischemic heart disease

Considerable experimental and clinical data indicate that sex has an important influence on cardiovascular physiology and pathology. This report integrates selected literature with new data from the Women's Ischemia Syndrome Evaluation (WISE) on vascular findings in women with ischemic heart disease (IHD) and how these findings differ from those in men. A number of common vascular disease-related conditions are either unique to (e.g., hypertensive disorders of pregnancy, gestational diabetes, peripartum dissection, polycystic ovarian syndrome, etc.) or more frequent (e.g., migraine, coronary spasm, lupus, vasculitis, Raynaud's phenomenon, etc.) in women than men. Post-menopausal women more frequently have many traditional vascular disease risk conditions (e.g., hypertension, diabetes, obesity, inactivity, and so on), and these conditions cluster more frequently in them than men. Considerable evidence supports the notion that, with these requisite conditions, women develop a more severe or somewhat different form of vascular disease than men. Structurally, women's coronary vessels are smaller in size and appear to contain more diffuse atherosclerosis, their aortas are stiffer (fibrosis, remodeling, and so on), and their microvessels appear to be more frequently dysfunctional compared with men. Functionally, women's vessels frequently show impaired vasodilator responses. Limitations of existing data and higher risks in women with acute myocardial infarction, need for revascularization, or heart failure create uncertainty about management. A better understanding of these findings should provide direction for new algorithms to improve management of the vasculopathy underlying IHD in women.

Monocytes of preeclamptic women spontaneously synthesize pro-inflammatory cytokines

The maternal syndrome preeclampsia is characterized by a generalized inflammatory response with activation of circulating leukocytes and altered levels of inflammatory cytokines. We hypothesized that one potential source of inflammatory cytokines during preeclampsia is the circulating maternal monocytes. By using flow cytometry, we found that the spontaneous intracellular synthesis of IL-1beta, IL-6, and IL-8 in monocytes of preeclamptic women was higher than in normal pregnant and non-pregnant women. The highest levels of cytokines were detected in women with the most abnormal laboratory values. When stimulated with lipopolysaccharide (LPS), the percentage of IL-1beta+ monocytes was lower in preeclampsia (72.6% +/- 8.2 SEM) than in normal pregnancy (90.7% +/- 2 SEM) (P = 0.03) and non-pregnant women (92.5% +/- 1.4 SEM) (P = 0.04) suggesting that monocytes from preeclamptic patients cannot be further stimulated. These results indicate that maternal circulating monocytes represent a source of inflammatory cytokines during preeclampsia.

The role of excessive volume expansion in the pathogenesis of preeclampsia

Preeclampsia is a disorder which is responsible for significant maternal morbidity and mortality as well as fetal wastage. Its pathogenesis remains obscure and its only treatment is the delivery of the placenta and the fetus. Over time it has become clear that this syndrome is not a single disease but a disorder with, most likely, multiple etiologic factors that have a common (or similar) phenotype(s). A leading hypothesis, first developed in the early 1970s, is that the hypertension, proteinuria and intrauterine growth restriction are the result of hypoperfusion of the maternal-fetal unit. However, the early events leading to this deranged circulatory event have not been extensively studied. We hypothesize that at least one of the early pathogenetic events is excessive expansion of the extracellular fluid volume. This leads to persistent elaboration of (a) circulating factor(s) that interfere(s) with remodeling of the decidual vasculature preventing normal placentation from occurring. Our experiments have dealt largely with the role that an endogenous bufadienolide, marinobufagenin (MBG), plays in this pathogenetic process. In this report, we provide evidence for this thesis and point to future studies aimed at testing this hypothesis. These will include evaluating large groups of preeclamptic patients to determine their blood and urinary levels of MBG. Efforts will also be made to determine if there are differences in sodium handling in those patients with elevated levels of MBG, compared to other preeclamptic patients and to normal pregnant subjects.

Upregulation of endothelial cell Ca2+ signaling contributes to pregnancy-enhanced vasodilation of rat uteroplacental arteries

Normal pregnancy is characterized by an increased uterine blood flow due to growth and remodeling of the maternal uterine vasculature and enhanced vasodilation of the uterine arteries. The objective of the present study was to examine the role of endothelial cell Ca2+ signaling in augmented endothelium-mediated vasodilation of uteroplacental arteries in late pregnancy. We performed fura-2-based measurements of the intracellular Ca2+ concentration ([Ca2+]i) in the cytoplasm of endothelial cells simultaneously with diameter in pressurized uterine arteries from nonpregnant (NP) and late-pregnant (LP) rats. Basal levels of endothelial cell [Ca2+]i were higher in arteries from LP rats compared with NP controls. Withdrawal of extracellular Ca2+ resulted in a decrease in the level of basal [Ca2+]i that was significantly larger in arteries of LP than NP rats. The rate of Mn2+ -induced quenching of fura-2 fluorescence was significantly elevated in late pregnancy, implicating augmented Ca2+ influx as a cause of increased basal levels of [Ca2+]i in endothelial cells. Elevation of intraluminal pressure resulted in a transient increase in endothelial [Ca2+]i that was markedly potentiated in late gestation. ACh-induced [Ca2+]i and vasodilator responses were significantly augmented in arteries of LP compared with NP rats and were abolished by BAPTA treatment, demonstrating a critical role of [Ca2+]i elevation in the production of endothelium-derived vasodilators. Together, these results indicate that late pregnancy is a state of enhanced basal and stimulated Ca2+ signaling in endothelial cells of uterine vessels, which may represent an important underlying mechanism for augmented vasodilation in the maternal uterine circulation.

Impact of genes related to immune tolerance and inflammation (tumour necrosis factor-α, interleukin-6) on blood pressure, protein excretion and oedema in pregnancy

OBJECTIVE

To test the hypothesis that genetically determined alterations of maternal immune tolerance to a foetal semi-allograft are important for the pathogenesis of hypertensive disorders in pregnancy.

DESIGN

A genetic association study was performed to analyse the impact of genetic polymorphisms known to be involved in immune tolerance on markers of pre-eclampsia.

SETTING

The study was conducted at the Obstetrics Department of the Charité University Hospital, Berlin, Germany.

PARTICIPANTS

A total of 1480 Caucasian women were consecutively included after delivery and genotyped for two polymorphisms: tumour necrosis factor-alpha -308G>A and interleukin-6 -174G>C.

MAIN OUTCOME MEASURES

Systolic and diastolic blood pressures, urinary protein excretion and oedema during pregnancy.

RESULTS

Only women carrying at least one mutant allele of both polymorphisms (tumour necrosis factor-alpha A and interleukin-6 C) have a significantly elevated mean systolic blood pressure and diastolic blood pressure at the end of pregnancy. The tumour necrosis factor-alpha A allele on its own is significantly associated with urinary protein excretion in the last trimenon, and the interleukin-6 C allele is independently and significantly associated with new-onset oedema.

CONCLUSIONS

We demonstrate in a large population that common maternal polymorphisms of genes related to immune tolerance and inflammation are associated with blood pressure regulation, urinary protein excretion and oedema during pregnancy. The analysed polymorphisms seem to contribute to the multifactorial pathogenesis of gestational hypertension and pre-eclampsia. The findings support the hypothesis that genetically determined factors of maternal immune tolerance play a role in the pathogenesis of hypertensive disorders in pregnancy.

Metabolic Syndrome and the Risk of Placental Dysfunction

BACKGROUND

Placental dysfunction (PD), which may manifest partly as the hypertensive disorders of pregnancy and abruption or infarction of the placenta, occurs more commonly in women with obesity, chronic hypertension, diabetes mellitus, and dyslipidemia-each a major feature of the metabolic syndrome. However, the relationship between the metabolic syndrome and the future risk of PD or fetal demise is unknown.

METHODS

We completed a retrospective cohort study of 1.03 million women who had a first documented delivery in the province of Ontario between 1990 and 2002. Using linked administrative databases, we categorized women as having zero, one, two, or three to four features of the metabolic syndrome up to 24 months before their index delivery hospitalization. Women were considered to have placental dysfunction if they had a diagnosis of preeclampsia, gestational hypertension, placental abruption, or placental infarction during their first hospitalization for delivery in the period of study.

RESULTS

At the time of delivery, 75 380 women (7.3%) were diagnosed as having PD. There was a progressive increase in the risk of PD in women with one (adjusted odds ratio [OR] 3.1; 95% confidence interval [CI] 3.0-3.1), two (OR 5.5; 95% CI 5.2-5.8), or three to four (OR 7.7; 95% CI 6.7-8.9) features of the metabolic syndrome, compared with none. A similar gradient effect was seen for the combined outcome of PD with poor fetal growth, or of PD with concomitant fetal death.

CONCLUSIONS

Women who exhibit features of the metabolic syndrome before pregnancy have a higher graded risk of PD and fetal demise. Studies are needed to determine whether modifying a woman's metabolic profile before pregnancy, through modest caloric restriction and increased physical activity, can lower her future risk of PD.

Cardiovascular health after maternal placental syndromes (CHAMPS): population-based retrospective cohort study

BACKGROUND

Maternal placental syndromes, including the hypertensive disorders of pregnancy and abruption or infarction of the placenta, probably originate from diseased placental vessels. The syndromes arise most often in women who have metabolic risk factors for cardiovascular disease, including obesity, pre-pregnancy hypertension, diabetes mellitus, and dyslipidaemia. Our aim was to assess the risk of premature vascular disease in women who had had a pregnancy affected by maternal placental syndromes.

METHODS

We did a population-based retrospective cohort study in Ontario, Canada, of 1.03 million women who were free from cardiovascular disease before their first documented delivery. We defined the following as maternal placental syndromes: pre-eclampsia, gestational hypertension, placental abruption, and placental infarction. Our primary endpoint was a composite of cardiovascular disease, defined as hospital admission or revascularisation for coronary artery, cerebrovascular, or peripheral artery disease at least 90 days after the delivery discharge date.

FINDINGS

The mean (SD) age of participants was 28.2 (5.5) years at the index delivery, and 75 380 (7%) women were diagnosed with a maternal placental syndrome. The incidence of cardiovascular disease was 500 per million person-years in women who had had a maternal placental syndrome compared with 200 per million in women who had not (adjusted hazard ratio [HR] 2.0, 95 CI 1.7-2.2). This risk was higher in the combined presence of a maternal placental syndrome and poor fetal growth (3.1, 2.2-4.5) or a maternal placental syndrome and intrauterine fetal death (4.4, 2.4-7.9), relative to neither.

INTERPRETATION

The risk of premature cardiovascular disease is higher after a maternal placental syndrome, especially in the presence of fetal compromise. Affected women should have their blood pressure and weight assessed about 6 months postpartum, and a healthy lifestyle should be emphasised.

Androgen levels in the third trimester of pregnancy in patients with preeclampsia

OBJECTIVE(S)

To investigate if testosterone levels are higher in patients with preeclampsia compared to normotensive pregnant patients.

STUDY DESIGN

The levels of serum total and free testosterone, dehydroepiandrosterone sulfate, androstenedione and sex hormone binding globulin were estimated in 28 patients during the third trimester of pregnancy with established preeclampsia and 25 normotensive women.

RESULTS

No statistically significant differences were noted between the two groups regarding the maternal age, gestational age, body mass index (BMI) haematocrit and neonatal sex. The mean+/-S.D. total testosterone and free testosterone levels were significantly higher (p < 0.01) in the group with preeclapsia compared to the control group. The values of DHEA-S, androstenedione and sex hormone binding globulin were lower in the group with preeclampsia but the difference did not reach statistical significance.

CONCLUSION(S)

The levels of total and free testosterone appear to be higher in patients with preeclampsia compared to normotensive pregnant women during the third trimester of pregnancy. This difference could indicate an involvement of testosterone in the pathophysiology of preeclampsia and stimulates research in the potential role of anti-androgens in the management of preeclampsia.

Involvement of marinobufagenin in a rat model of human preeclampsia

BACKGROUND

Preeclampsia is a potentially devastating disorder of hypertension in pregnancy for which there is currently no definitive treatment short of delivery. The bufadienolide, marinobufagenin (MBG), an inhibitor of Na(+)/K(+) ATPase, has been found to be elevated in extracellular fluid volume-expanded hypertensive patients, a condition similar to preeclampsia. Thus, these studies sought to examine the role of MBG in our rat model of preeclampsia.

METHODS AND RESULTS

Pregnant female rats were injected intraperitoneally with deoxycorticosterone acetate (DOCA) and given 0.9% saline as drinking water for the duration of their pregnancy. Urinary MBG was measured using a DELFIA immunoassay. Blood pressure was measured via the tail-cuff method. Injections of anti-MBG antibody were given intraperitoneally or intravenously to hypertensive pregnant rats. MBG was given intraperitoneally to pregnant rats. Uterine arterioles were dissected free and their diameters were measured before and after perfusion of MBG, ouabain, or digoxin. MBG was found to be elevated in the pregnant + DOCA + saline (PDS) rats compared to normal pregnant animals. In addition, when PDS rats were injected with anti-MBG antibody, there was a subsequent reduction in blood pressure. Administration of MBG in normal pregnant rats caused an elevation in blood pressure equivalent to the PDS model. Also, uterine vessel measurements showed an increased vasoconstrictive reactivity to MBG in the PDS animals vs. the normal pregnant controls; while no changes were observed with perfusion of digoxin or ouabain at the same concentration.

CONCLUSION

These results suggest a relationship between MBG and a syndrome in rats resembling preeclampsia. Armed with these promising results, it would seem logical to further examine the role of MBG in human preeclampsia.

Hyperhomocysteinemia in pregnant rats: effects on arterial pressure, kidneys and fetal growth

OBJECTIVE

This study aimed to test the hypothesis that hyperhomocysteinemia plays a role in the development of pathological changes similar to human preeclampsia in pregnant rats.

STUDY DESIGN

Arterial pressure and 24-h urinary excretion of proteins and electrolytes were measured during pre-pregnancy, pregnancy and postpartum periods in control (n = 12) and methionine-treated (2.0 g/kg/day, n = 11) Sprague-Dawley rats. Rats were then sacrificed at the end of this protocol and renal histological examination was performed. In another protocol, control (n = 6) and methionine-treated (n = 6) rats were anaesthetized at day 20 of gestation and pregnancy outcome was assessed. Hemodynamic and renal excretory differences between groups were analyzed using ANOVA and differences in renal histology and gestation outcome using t-test.

RESULTS

Serum homocysteine in the methionine group (24.0+/-2.0 micromol/L) was significantly higher compared with controls (8.5+/-0.5 micromol/L). Systolic pressure, urinary protein excretion and renal histological changes were not significantly different between the two groups. However, fetal weights were significantly smaller and percent of dead fetuses were 15% higher in methionine-treated compared with control rats.

CONCLUSION

Hyperhomocysteinemia is unlikely to cause maternal hypertension, proteinuria or renal damage in pregnant rats. However, hyperhomocysteinemia may restrict fetal growth and increase fetal mortality.

Assessment of risk for the development of pre-eclampsia by maternal characteristics and uterine artery Doppler

OBJECTIVE

To develop a method for the estimation of patient-specific risk for the development of pre-eclampsia by combining maternal history and uterine artery Doppler.

DESIGN

Prospective multicentre observational study.

SETTING

Antenatal clinics in seven hospitals in the UK and three overseas centres.

POPULATION

Unselected women with singleton pregnancies attending for routine antenatal care.

METHODS

Doppler studies of the uterine arteries were performed using colour flow mapping and pulsed wave Doppler at 23 weeks of gestation. The mean pulsatility index (PI) of the two uterine arteries was calculated. Doppler and maternal history variables were combined to develop a model for risk assessment. The incidence of pre-eclampsia was used to derive the prior risk for this complication. The posterior risk was derived by multiplying the prior odds with likelihood ratios (LRs) derived from independent risk factors identified from the maternal history, and the LR estimated from the heights of the frequency distributions of mean PI in affected and unaffected pregnancies.

MAIN OUTCOME MEASURE

Pre-eclampsia.

RESULTS

There were 17,480 women recruited to the study, in which 17,319 (99.1%) of these Doppler examination of both uterine arteries were completed, and outcome data were available in 16,806 (97.0%). Pre-eclampsia occurred in 369 (2.20%) cases. Significant independent prediction of pre-eclampsia was provided by mean PI, ethnic origin, body mass index (BMI), parity, cigarette smoking, history of hypertension and family or personal history of pre-eclampsia. Models were derived allowing calculation of patient-specific risk for development of pre-eclampsia. For a false-positive rate of 25%, the detection rate of pre-eclampsia by screening using maternal history was 45.3%, with uterine artery Doppler it was 63.1% and with combined assessment it was 67.5%.

CONCLUSIONS

Combining risk factors in the mother's history with Doppler of the uterine arteries allows calculation of patient-specific risk for the development of pre-eclampsia.

Association of apolipoprotein J gene 866C-->T polymorphism with preeclampsia and essential hypertension

The etiology of preeclampsia (PE) is unknown, but endothelial cell injury plays a pivotal role. Moreover, there is a significantly positive association between PE and later hypertension. Apolipoprotein J (apo J) plays an important role in stabilizing cell membranes at diverse fluid-tissue interfaces and might protect vascular endothelium against an attack by some factors in plasma such as active complement complexes. This study investigated the prevalence and possible association of apo J gene in PE and essential hypertension (EH). To screen for polymorphisms of apo J gene in a population in Guizhou, China, by employing polymerase chain reaction combined with denaturing gradient gel electrophoresis, we identified 866C-->T polymorphism in exon 5 and a rare variant 1061C-->T in exon 7. The CT genotype and T-allele frequencies in PE (CT genotype 26%; T allele 13%) and EH (CT genotype 28.57%; T allele 17.14%) were significantly lower than that in the control group (CT geno type 50%; T allele 27%). The results suggested that the 866C-->T polymorphism might be associated with PE and EH. It is plausible that apo J may play a certain role in the predisposition to PE and EH.

Placental dysfunction in Suramin-treated rats – a new model for pre-eclampsia

Impaired placentation and oxidative stress are proposed to play major roles in the pathogenesis of placental dysfunction and pre-eclampsia. This study was carried out to evaluate if inhibited angiogenesis by Suramin injections in early pregnancy may cause a condition resembling pre-eclampsia in rats. Rats of two different Sprague-Dawley strains, U and H, were given intraperitoneal injections of Suramin or saline in early pregnancy. The outcome of pregnancy was evaluated on gestational day 20. Suramin injections caused increased blood pressure and decreased renal blood flow in the U rats. In both rat strains Suramin decreased the placental blood flow and caused fetal growth retardation. In both strains the placental concentration of the isoprostane 8-epi-PGF2alpha was increased, indicating oxidative stress. The serum concentration of Endothelin-1 was increased in the U rats. The U strain had a lower basal placental blood flow, and the effects of Suramin were more pronounced in this strain. We conclude, that Suramin injections to pregnant rats cause a state of placental insufficiency, which partly resembles human pre-eclampsia. The induction of this condition is at least partly mediated by oxidative stress, and is subject to varied genetic susceptibility.

Changes in serum levels of heat shock protein 70 in preterm delivery and pre-eclampsia

AIM

The aim of this study was to investigate heat-shock protein (Hsp)70 as a novel marker to evaluate the curative effects of treatment for preterm delivery high-risk patients and pre-eclampsia.

METHODS

After obtaining informed consent, serum samples were collected from 31 preterm delivery high-risk patients with a tocolysis index of three points or above (A), seven pre-eclampsia patients (P), 46 normal pregnant women (B), and seven non-pregnant women (C). Of the 31 preterm delivery high-risk patients, 15 had preterm delivery (Ap) and 16 had full-term delivery (Af). The levels of Hsp70 were measured using enzyme-linked immunosorbent assay.

RESULTS

The Hsp70 levels in normal pregnant women were 8.6 +/- 1.9 ng/mL (first trimester), 5.5 +/- 1.0 ng/mL (second trimester) and 5.5 +/- 0.7 ng/mL (third trimester). There was no statistical difference in the Hsp70 levels between the three trimesters. The mean Hsp70 levels were 21.9 +/- 5.3 ng/mL (A), 35.3 +/- 9.6 ng/mL (Ap), 9.4 +/- 2.2 ng/mL (Af), 24.4 +/- 3.6 ng/mL (P), 6.1 +/- 0.6 ng/mL (B), and 2.4 +/- 0.6 ng/mL (C). Group Ap had significantly higher Hsp70 levels than group Af (P = 0.0112) and group B (P <0.0001). The duration of pregnancy after hospitalization for group Ap was significantly shorter than that for group Af (P=0.0088) and group B (P <0.0001). Group P also had significantly higher Hsp70 levels than group B (P <0.0001).

CONCLUSION

Because Hsp70 levels were particularly high in treatment-resistant preterm delivery cases, Hsp70 may prove to be a useful marker for evaluating the curative effects of treatment for preterm delivery.

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.

Insulin and nitric oxide stimulates glucose transport in human placenta

The present work examines whether insulin and NO can act as regulators of glucose transport in placenta. Glucose uptake (2-deoxy D-[(3)H]glucose) was measured in the absence (control or basal values) and in the presence of insulin (1200 microU/ml) or SNP (20 microM) in isolated perfused cotyledons and tissue slices preparations of human placenta. Both insulin and NO significantly increased glucose uptake by 20 and 27 per cent, respectively. Insulin decreased the Km of glucose transport from 42.5 +/- 2.69 to 35.1 +/- 2.58 mM. The stimulatory effect of SNP was mimicked by 8-CPT-cGMP and was completely blocked by the guanylate cyclase inhibitor, ODQ (10 microM). ODQ and the NOS inhibitor, L-NAME (100 microM), decreased basal glucose uptake but did not affect insulin-stimulated glucose transport. Taken together, these findings indicate that insulin and NO stimulate glucose uptake in human placenta and suggest that both potential regulators of glucose transport use different signaling pathways.

Haplotypic association of DDAH1 with susceptibility to pre-eclampsia

Association between pre-eclampsia (PEE1) and the dimethylarginine dimethylaminohydrolase (DDAH) 1 and 2 genes, which play a role in the regulation of nitric oxide synthesis and release, was studied. In a case-control study design single nucleotide polymorphisms (SNPs) were determined at eight sites in the DDAH1 gene and at one site (Pro231Pro) in the DDAH2 gene from 132 women with pre-eclampsia and 112 healthy controls. Three SNPs in the DDAH1 gene were associated with pre-eclampsia, showing complete linkage disequilibrium with each other, but none of the associations in the allele or genotype data reached statistical significance in either of the genes after the correction for multiple testing. Haplotype frequencies were estimated using a population based on a maximum likelihood method (EM algorithm). Four common DDAH1 haplotypes were present and a significant association of haplotypes H2 and H3 with pre-eclampsia (P=0.03) was found. The risk of pre-eclampsia was greatest in individuals (odds ratio: 3.93; 95% confidence interval: 1.54-9.99) who had two copies of the high-risk haplotypes (H2 or H3). The observed haplotypic association provides the first evidence of the importance of DDAH1 polymorphisms in pre-eclampsia susceptibility.

Recent progress in the therapeutic management of pre-eclampsia

Pre-eclampsia is a pregnancy-specific syndrome of unknown aetiology, observed in 3 - 5% of all pregnancies, associated with pathological vascular lesions in multiple organs, activation of the coagulation system, and maternal multisystemic and fetal complications. Clinically, pre-eclampsia is characterised by the onset of hypertension, proteinuria and oedema, usually beginning in the third trimester. Conventionally, antihypertensive agents are the main pharmacological treatment. Recently, some studies have shown that the treatment of pre-eclampsia with antithrombin concentrate corrects the hypercoagulability and improves the fetal status and the perinatal outcome. No clear evidence supports the use of heparin. A conservative treatment of moderate- to- severe pre-eclampsia, based on the administration of antithrombin concentrate, may allow a significant prolongation of pregnancy and a better neonatal outcome, as well as fewer maternal complications.

RETRACTED: Transcriptional regulation of the AT1 receptor gene in immortalized human trophoblast cells

Studies investigating the mechanisms that govern the expression of the human angiotensin II (Ang II) type 1 receptor (hAT1R) gene have progressed slowly due to the lack of human cell lines that express the AT1R. Recently, however, an immortalized human trophoblast cell line (HTR-8/SVNeo) was demonstrated to respond to Ang II. Therefore, we utilized this cell line to characterize the AT1R expressed on the cell surface and to investigate the mechanisms by which the hAT1R gene is regulated in these cells. HTR-8/SVNeo cells were shown to express functional high affinity AT1Rs having a Bmax value of 114+/-11 fmol/mg protein and a Kd value of 0.14+/-0.1 nM. Additionally, Ang II-induced IP3 production was mediated via the AT1R. Deletional analysis of the hAT1R promoter localized a major basal regulatory sequence within the -105 to -79 bp region, relative to the transcription start site, in HTR-8/SVNeo cells. Electrophoretic mobility shift assay (EMSA) and Chromatin Immunoprecipitation (ChIP) assay demonstrated that the transcription factors, Sp1 and Sp3, interact with this region of the hAT1R promoter in vitro and in vivo. Taken together, our data demonstrate that HTR-8/SVNeo cells express functional AT1Rs and that basal level expression of this gene is regulated, in part, by Sp1 and Sp3 in this cell line.

Thickening of the amnion basement membrane and its relationship to placental inflammatory lesions and fetal and maternal disorders

OBJECTIVE

The aim of this study is the morphological and morphometric analysis of the basement membrane amniotic epithelium of the chorionic plate to establish possible correlation between the basement membrane amniotic epithelium thickening and maternal and fetal disorders.

STUDY DESIGN

Ninety-one placentas of infants delivered in Medical Hospital School were studied with hematoxylin-eosin (H&E) and Periodic Acid Schiff (PAS) methods, morphometric and ultrastructural analysis.

RESULTS

Of the 91 placentas analyzed, 17 (18.6%) were normal with regard to placental morphology, fetal and maternal history. Basement membrane amniotic epithelium thickening was significantly greater in the cases associated with chorioamnionitis (P=0.013), villitis (P=0.040), maternal hypertension syndromes during pregnancy (P=0.027) and stillborn (P=0.040) babies. The electron microscopic examination of the basement membrane amniotic epithelium identified a structural alteration and edema of the dense lamina.

CONCLUSION

Thickening of the basement membrane amniotic epithelium was associated with morphologic placental abnormalities and/or fetal or maternal disorders. Thickening of the basement membrane amniotic epithelium was identified away from the site of placental inflammation, possibly being a consequence of cytokines, supporting more than a local effect. This could be a new insight into the pathogenesis of fetal and maternal complications associated with inflammatory placental lesions.