Pre-eclampsia, the placenta and the maternal systemic inflammatory response--a review

Distribution of CD14+ and CD68+ Macrophages in the Placental Bed and Basal Plate of Women With Preeclampsia and Preterm Labor

OBJECTIVE

Macrophages play a key role in implantation, placentation and parturition. Yet, whether or not the number of macrophages at the fetomaternal interface (basal plate of the placenta and placental bed) is altered in women with preeclampsia is the subject of controversy. The purpose of this study was to compare the immunoreactivity and distribution patterns of CD14 and CD68 positive macrophages in both the basal plate and placental bed from preeclamptic and non-preeclamptic pregnancies.

METHODS

A cross-sectional study was conducted. Paraffin embedded sections of placental tissues and placental bed biopsies were obtained from patients with early onset preeclampsia (n=10) and from those with preterm labor/delivery (n=10) without preeclampsia matched for gestational age. Double immunohistochemistry using antibodies to CD14 and CD68 was performed, and the density of double or single positive cells in the basal plate and placental bed was evaluated. Non-parametric statistics were used for analysis.

RESULTS

1) A unique subset of CD14-/CD68+ cells was identified. The cells in question were present at a higher level in the decidua than in the myometrial segment of the placental bed (p<0.01); 2) The density and proportion of CD14+/CD68+ cells (double positive cells) were significantly higher in the myometrial segment than in the basal plate (p=0.0003); and 3) There were no significant differences in the density and patterns of immunopositive macrophages in the basal plate, the decidua, and the myometrium between women with preeclampsia and those with preterm labor/delivery (p>0.05).

CONCLUSION

The macrophages at the fetomaternal interface can be dichotomized by CD14 and CD68 immunoreactivity. A gradient of CD14+/CD68+ macrophages was demonstrated between the superficial myometrium and the basal plate regardless of the etiology of preterm birth (preeclampsia or spontaneous preterm labor). The biological function of single positive (CD14-/CD68+) and double positive (CD14+/CD68+) macrophages at the fetomaternal interface remains to be established. The overall findings also suggest that the discrepancies in the literature are due to the varying markers used to detect macrophages and in the anatomical plane of the fetomaternal junction analyzed.

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.

Tumor necrosis factor-alpha in gestation and puerperium of women with gestational hypertension and pre-eclampsia

PROBLEM

High plasma levels of tumor necrosis factor-alpha (TNF-alpha) in pregnant women have been associated with the pathogenesis of pre-eclampsia (PE). This study evaluated TNF-alpha plasma levels and monocyte production in gestational hypertension (GH) and PE during gestation and at puerperium.

METHOD OF STUDY

This study included 128 women, of whom 20 were non-pregnant (NP) normotensive (NT), and 108 were pregnant: 36 NT, 27 with GH, and 45 with PE. Peripheral blood plasma was used for TNF-alpha and uric acid determination. TNF-alpha was determined in plasma and lipopolysaccharide (LPS)-stimulated and non-stimulated monocyte supernatants by L929 bioassay.

RESULTS

Tumor necrosis factor-alpha and uric acid plasma levels were higher in PE than in GH pregnancies. In both hypertensive groups, these parameters positively correlated and were significantly more elevated than in NT and NP women. TNF-alpha plasma levels and monocyte production were higher in hypertensive than in NT women during gestation, and significantly decreased at puerperium. Although decreased, TNF-alpha release in LPS-stimulated PE monocytes, was still significantly higher than in the other pregnant groups.

CONCLUSION

In vivo monocyte activation in GH and PE pregnant women was characterized by in vitro TNF-alpha production. The fact that higher circulating concentrations of TNF-alpha and uric acid were observed in PE than in GH suggests an association with disease severity.

Dual In Vitro Perfusion of an Isolated Cotyledon as a Model to Study the Implication of Changes in the Third Trimester Placenta on Preeclampsia

In the current study perfusions of an isolated cotyledon of term placenta using standard medium were compared to medium containing xanthine plus xanthine oxidase (X+XO), which generates reactive oxygen species (ROS). A time-dependant increase in the levels of different cytokines (TNF-alpha, IL-1ss, IL-6, IL-8 and IL-10) was observed between 1 and 7h with more than 90% of the total recovered from the maternal compartment with no significant difference between the 2 groups. For 8-iso-PGF2alpha 90% of the total was found in the fetal compartment and a significantly higher total release was seen in the X+XO group. Microparticles (MPs) isolated from the maternal circuit were identified by flow cytometry as trophoblastic sheddings, whereas MPs from the fetal circuit were predominantly derived from endothelial cells. More than 90% of the total of MPs was found in the maternal circuit. The absolute amount of the total as well as the maternal fraction were significantly higher in the X+XO group. Immunohistochemistry (IHC) of the perfused tissue revealed staining for IL-1beta of villous stroma cells, which became clearly more pronounced in experiments with X+XO. Western blot of tissue homogenate revealed 2 isoforms of IL-1beta at 17 and 31kD. In X+XO experiments there was a tendency for increased expression of antioxidant enzymes in the tissue. Western blot of MPs from the maternal circuit showed increased expression of antioxidant enzymes in the X+XO group and for IL-1beta only the 17kD band was detected. In vitro reperfusion of human placental tissue results in mild tissue injury suggestive of oxidative stress. In view of the increased generation of ROS in perfused tissue with further increase under the influence of X+XO, the overall manifestation of oxidative stress remained rather mild. Preservation of antioxidant capacity of human placental tissue could be a sign of integrity of structure and function being maintained in vitro by dual perfusion of an isolated cotyledon. The observed changes resemble findings seen in placentae from preeclampsia.

Endogenous inhibitors of nitric oxide and preeclampsia: a review

Nitric oxide (NO) is a potent vasodilator. NO is synthesized by NO synthases (NOS) and NOS are inhibited by asymmetrical dimethylarginine (ADMA). ADMA is metabolized by dimethylarginine dimethylaminohydrolase (DDAH) and excreted in the kidneys. Lower ADMA levels in pregnant women compared to non-pregnant controls suggest that ADMA has a role in vascular dilatation and blood pressure changes. Several studies show an increase in ADMA levels in pregnancies complicated with preeclampsia. Elevated ADMA levels in preeclampsia are seen before clinical symptoms have developed; these findings suggest that ADMA has a role in the pathogenesis of preeclampsia.

Could antioxidant supplementation prevent pre-eclampsia?

Pre-eclampsia is a disorder characterised by pregnancy-induced hypertension and new-onset proteinuria occurring in the second half of pregnancy. Worldwide, approximately 2–3% of all pregnant women develop pre-eclampsia. The condition is a major cause of maternal and fetal morbidity and mortality. Abnormal placentation is an important predisposing factor for pre-eclampsia, while endothelial activation appears to be central to the pathophysiological changes, possibly indicative of a two-stage disorder characterised by reduced placental perfusion and a maternal syndrome. There is increasing evidence that pre-eclampsia is associated with both increased oxidative stress and reduced antioxidant defences, which has led to the hypothesis that oxidative stress may play an important role in the pathogenesis of pre-eclampsia, perhaps acting as the link in a two-stage model of pre-eclampsia. In support of this hypothesis a small, but important, preliminary study has shown a highly significant (P= 0.02) reduction in the incidence of pre-eclampsia in women at risk who were taking a supplement of vitamins C and E from mid-pregnancy. Furthermore, these findings support the hypothesis that oxidative stress is at least partly responsible for the endothelial dysfunction of pre-eclampsia. Several larger multicentre trials are currently underway to evaluate the efficacy, safety and cost benefits of antioxidant supplementation during pregnancy for the prevention of pre-eclampsia in both low- and high-risk women, including women with diabetes. The results of these trials are awaited with interest.

Serum adiponectin levels in normal and hypertensive pregnancy

OBJECTIVE

The aim of this study was to quantify adiponectin levels in women with normal and hypertensive pregnancies to determine whether there is an independent association, while controlling for body fat and insulin sensitivity.

METHODS

A cross-sectional study was conducted in the following categories: 12 normotensive non-pregnant women, 10 normotensive, 12 gestational hypertensive, 13 essential hypertensive, and 12 preeclamptic women. All subjects underwent measurements of body fat by bio-impedance analysis and blood sampling.

RESULTS

Percentage of body fat and insulin resistance were greater in all pregnant groups compared with non-pregnant women. Adiponectin concentrations were significantly lower in women with normal pregnancies (18.6 +/- 1.4 microg/mL, p = 0.02) compared with non-pregnant women (24.0 +/- 1.5 microg/mL). However, adiponectin levels were not significantly different among normal pregnancy, gestational hypertension (19.0 +/- 3.1 microg/mL), essential hypertension (24.0 +/- 3.7 microg/mL) and pre-eclampsia (22.4 +/- 2.5 microg/mL) groups. Adiponectin levels were inversely related to percent body fat and insulin resistance. When adiponectin levels were corrected for percent body fat and insulin resistance, no significant differences were seen among the study groups.

CONCLUSIONS

Adiponectin levels are decreased in normal pregnancy, however this difference disappears when adiponectin levels are corrected for the pregnancy-related increases in body fat and insulin resistance. Adiponectin levels are not altered significantly in states of hypertension in pregnancy compared with normal pregnancy.

Clinical correlation between adenosine deaminase activity and pre-eclampsia severity

This study evaluated the relationship between the activity of the inflammatory indicator adenosine deaminase (ADA) in placental tissue and maternal and fetal (umbilical cord) plasma and the severity of pre-eclampsia. Maternal and umbilical vein whole blood and placental tissue samples were collected from women with normal pregnancies (n = 33) and patients with mild (n = 12) or severe (n = 17) preeclampsia. ADA activity was measured spectrophotometrically. Significantly increased ADA activity was detected in maternal and fetal plasma, and placental tissue in patients with mild and severe pre-eclampsia compared with normal pregnancies; there were no significant differences between the mild and severe cases. The presence of increased ADA activity in pre-eclampsia is consistent with activation of the inflammatory system in this condition. The increased ADA activity was related to the presence of the disease but not the severity of clinical symptoms. Neonatal outcome did not significantly correlate with observed ADA activity.

Immunoregulation in normal pregnancy and pre-eclampsia: an overview

Pre-eclampsia is a major disorder of human pregnancy, which may have an immunological basis. It is a disease of two stages. The first stage concerns the relative failure of early trophoblast invasion and remodelling of the spiral arteries, leading to a poor blood supply to the placenta, exposing it to oxidative stress. The inadequate trophoblast invasion may result from decreased expression of human leukocyte antigen-G (HLA-G) leading to an abnormal interaction with decidual natural killer (NK) cells, which are believed to play a major role in these processes through the production of immunoregulatory cytokines and angiogenic factors. Recent evidence suggests that the interaction between trophoblast human leukocyte antigen-C (HLA-C) molecules and decidual NK cell receptors may be the point at which the apparent partner specificity of the disease originates. The second stage is the maternal syndrome, which is characterized by a generalized systemic inflammatory response involving both leukocytes and endothelium. The inflammatory stimulus is believed to come from the placenta. In pre-eclampsia, placental oxidative stress may lead to increased shedding of apoptotic and/or necrotic syncytiotrophoblast debris into the maternal circulation. There is evidence that such trophoblast debris interacts with maternal leukocytes and endothelial cells to stimulate the release of proinflammatory cytokines, which could then trigger the maternal disease.

Innate immune response by ficolin binding in apoptotic placenta is associated with the clinical syndrome of preeclampsia

BACKGROUND

Unidentified circulating factors derived from placenta are thought to be responsible for the exaggerated systemic inflammation leading to preeclampsia. Our aim was to identify the circulating factors present in preeclampsia and to investigate their relationship to the underlying systemic immune response responsible for the associated clinical manifestations.

METHODS

We obtained blood samples from pregnant women with and without preeclampsia and performed comparative proteomic analyses to identify the abnormal circulating factors by 2-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption ionization time of flight for protein separation and identification. In placentas from preeclamptic pregnancies, we evaluated the potential role of the candidate proteins identified by Western and immunohistochemical analysis. We also used proinflammatory cytokine antibody arrays to investigate local and systemic immune responses.

RESULTS

We found that ficolins, the pattern-recognition proteins involved in the lectin-complement pathway, were differentially expressed in plasma from preeclamptic pregnancies. Ficolins were present in low concentrations in plasma but at high concentrations in the placenta, particularly in syncytiotrophoblasts undergoing apoptosis. The binding of ficolins in apoptotic trophoblasts induced innate immunity through local and systemic cytokine activation and correlated with the clinical manifestation of preeclampsia.

CONCLUSIONS

We identified specific in vivo circulating factors derived from the placenta that are responsible for the local immune recognition and systemic inflammatory response in the development of clinical manifestations of preeclampsia. These findings may have predictive value and also therapeutic applications to lessen adverse clinical outcomes of preeclampsia.

Inositol Phosphoglycan P-Type in Preeclampsia

A state of insulin resistance has been demonstrated in active preeclampsia, and women with clinical evidence of insulin resistance are at higher risk to develop this syndrome during pregnancy. Recently, inositol phosphoglycan P-type, a putative second messenger of insulin action, has been implicated in the pathophysiology of preeclampsia and is increased in the placenta, amniotic fluid, and maternal urine of preeclamptic women compared with normal pregnant women. We report here a case–control study to assess the potential of urinary levels of inositol phosphoglycan P-type as a screening test for preeclampsia. Twenty-seven preeclamptic women and 47 healthy pregnant women were recruited. A polyclonal antibody-based ELISA was developed to detect levels of inositol phosphoglycan P-type in urine. Its content in urinary specimens was found to be 30-fold higher in preeclamptic subjects than control subjects (329.1±21.8 versus 9.2±1.5; P <0.001), with a higher level in all of the preeclamptic cases. For 6 women who developed preeclampsia, >1 gestational date sample of urine was available, and retrospective analysis showed a significant time-related increase of the urinary level of inositol phosphoglycan P-type ≤7 weeks before clinical diagnosis of preeclampsia. Urinary level of inositol phosphoglycan P-type increased after diagnosis indicating a possible pathophysiological threshold level and steeply decreased after delivery.

Candidate-gene association study of mothers with pre-eclampsia, and their infants, analyzing 775 SNPs in 190 genes

Pre-eclampsia (PE) affects 5-7% of pregnancies in the US, and is a leading cause of maternal death and perinatal morbidity and mortality worldwide. To identify genes with a role in PE, we conducted a large-scale association study evaluating 775 SNPs in 190 candidate genes selected for a potential role in obstetrical complications. SNP discovery was performed by DNA sequencing, and genotyping was carried out in a high-throughput facility using the MassARRAY(TM) System. Women with PE (n = 394) and their offspring (n = 324) were compared with control women (n = 602) and their offspring (n = 631) from the same hospital-based population. Haplotypes were estimated for each gene using the EM algorithm, and empirical p values were obtained for a logistic regression-based score test, adjusted for significant covariates. An interaction model between maternal and offspring genotypes was also evaluated. The most significant findings for association with PE were COL1A1 (p = 0.0011) and IL1A (p = 0.0014) for the maternal genotype, and PLAUR (p = 0.0008) for the offspring genotype. Common candidate genes for PE, including MTHFR and NOS3, were not significantly associated with PE. For the interaction model, SNPs within IGF1 (p = 0.0035) and IL4R (p = 0.0036) gave the most significant results. This study is one of the most comprehensive genetic association studies of PE to date, including an evaluation of offspring genotypes that have rarely been considered in previous studies. Although we did not identify statistically significant evidence of association for any of the candidate loci evaluated here after adjusting for multiple testing using the false discovery rate, additional compelling evidence exists, including multiple SNPs with nominally significant p values in COL1A1 and the IL1A region, and previous reports of association for IL1A, to support continued interest in these genes as candidates for PE. Identification of the genetic regulators of PE may have broader implications, since women with PE are at increased risk of death from cardiovascular diseases later in life.

Acute activation of the endothelium results in increased levels of active von Willebrand factor in hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome

BACKGROUND

HELLP (hemolysis, elevated liver enzymes and low platelets) syndrome is a severe complication of pre-eclampsia in pregnancy, characterized by microvascular platelet thrombi. Activation of the endothelium is thought to play a key role in pre-eclampsia and HELLP syndrome. Activation of endothelial cells may lead to release of von Willebrand factor (VWF) multimers, which are highly reactive with platelets. Normally, newly released multimers are cleaved by ADAMTS13, resulting in less reactive derivatives.

OBJECTIVE

We hypothesized that HELLP syndrome is characterized by increased amounts of active VWF compared with healthy pregnancy and pre-eclampsia, due to acute activation of endothelial cells. This might contribute to thrombocytopenia and thrombotic microangiopathy.

METHODS

Active VWF and ADAMTS13 activity were measured in healthy pregnant volunteers (n = 9), patients with pre-eclampsia (n = 6) and patients with HELLP syndrome (n = 14) at similar gestational ages. To study the role of endothelial cell activation, the propeptide/mature VWF ratio was determined, and VWF released by cultured endothelial cells was analyzed.

RESULTS

Active VWF levels were increased 2.1-fold in HELLP syndrome compared with healthy pregnant volunteers (P < 0.001) and 1.6-fold compared with patients with pre-eclampsia (P = 0.001). ADAMTS13 activity was moderately decreased in patients with HELLP syndrome compared with healthy pregnant volunteers (P < 0.004), but not compared with patients with pre-eclampsia. The propeptide/mature VWF ratio was increased 1.7-fold compared with healthy pregnant volunteers (P < 0.001) and 1.5-fold compared with patients with pre-eclampsia (P < 0.05). A significant correlation was found between this ratio and the activation factor of VWF (r = 0.68, P < 0.001). The amount of active VWF was increased 1.4-fold in medium of stimulated endothelial cells when compared with non-stimulated cells (P < 0.05).

CONCLUSION

Acute endothelial cell activation in HELLP syndrome and decreased ADAMTS13 activity result in increased amounts of active VWF. This might explain the consumptive thrombocytopenia and thrombotic microangiopathy associated with HELLP syndrome. Inhibition of circulating active VWF could be a potential new approach in the treatment of patients with HELLP syndrome.

Expressional and epigenetic alterations of placental serine protease inhibitors: SERPINA3 is a potential marker of preeclampsia

Preeclampsia is the major pregnancy-induced hypertensive disorder. It modifies the expression profile of placental genes, including several serine protease inhibitors (SERPINs). The objective of this study was to perform a systematic expression analysis of these genes in normal and pathological placentas and to pinpoint epigenetic alterations inside their promoter regions. Expression of 18 placental SERPINs was analyzed by quantitative RT-PCR on placentas from pregnancies complicated by preeclampsia, intrauterine growth restriction, or both and was compared with normal controls. SERPINA3, A5, A8, B2, B5, and B7 presented significant differences in expression in >or=1 pathological situation. In parallel, the methylation status of the CpG islands located in their promoter regions was studied on a sample of control and preeclamptic placentas. Ten SERPIN promoters were either totally methylated or totally unmethylated, whereas SERPINA3, A5, and A8 presented complex methylation profiles. For SERPINA3, the analysis was extended to 81 samples and performed by pyrosequencing. For the SERPINA3 CpG island, the average methylation level was significantly diminished in preeclampsia and growth restriction. The hypomethylated CpGs were situated at putative binding sites for developmental and stress response (hypoxia and inflammation) factors. Our results provide one of the first observations of a specific epigenetic alteration in human placental diseases and provide new potential markers for an early diagnosis.

Antihypertensive drugs clonidine, diazoxide, hydralazine and furosemide regulate the production of cytokines by placentas and peripheral blood mononuclear cells in normal pregnancy

BACKGROUND

Antihypertensive drugs such as clonidine, diazoxide, hydralazine and furosemide are used in the hypertensive disorders of pregnancy to control blood pressure, but it is not clear if they modulate the production of placental or circulating cytokines.

OBJECTIVE

To examine the effect of pharmaceutical doses of well known antihypertensive drugs used for blood pressure control on the production of the cytokines interleukin (IL)-6, IL-10 and tumour necrosis factor (TNF)-alpha in placental tissue and peripheral blood mononuclear cells (PBMCs) in normal pregnancy.

DESIGN

Placental biopsies were taken from the decidual surface of placentas after delivery of normal pregnancies (n = 6) and PBMCs were separated from the whole blood of normal term pregnant women (n = 7). Both villous explants and PBMCs were cultured with increasing concentrations of antihypertensive drugs. The dose effect of drugs on the production of placental and circulating cytokines (IL-6, IL-10 and TNF-alpha) were examined by enzyme-linked immunosorbent assay.

RESULTS

Placental production of IL-10 was not affected by clonidine, but decreased significantly after incubation of the tissue with diazoxide, hydralazine or furosemide. Production of IL-10 by PBMCs increased significantly: by from 3.4 +/- 2.7% [16.3 pg/ml (range 6.1-21.5 pg/ml)] to 24.5 +/- 3.3% [30.4 pg/ml (range 16.9-34.8 pg/ml)] with increasing concentrations of clonidine (0.08-1.3 microg/ml), and by 8.8 +/- 3.5% [4.1 pg/ml (range 3.0-17.8 pg/ml)] and 17.2 +/- 1.9% [22.6 pg/ml (range 13.2-23.2 pg/ml)] with lower doses of hydralazine (6.3 and 12.5 microg/ml) (all P values < 0.05). There was a stepwise reduction in production of TNF-alpha and IL-6 with increasing doses of diazoxide, hydralazine and furosemide by placentas and PBMCs from these women with normal pregnancies.

CONCLUSION

Our data suggest that the antihypertensive drugs clonidine and hydralazine can stimulate production of the circulating anti-inflammatory cytokine IL-10, whereas furosemide and diazoxide inhibit the production of this cytokine and the proinflammatory cytokines TNF-alpha and IL-6 by placentas and PBMCs.

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.

Heparin-mediated extracorporeal low density lipoprotein precipitation as a possible therapeutic approach in preeclampsia

Preeclampsia is a pregnancy-related hypertensive disease resulting in substantial maternal and neonatal morbidity and mortality. Until today there is no satisfactory treatment to stop disease progression except immediate delivery of the fetus. Heparin-mediated extracorporeal low density lipoprotein (LDL) precipitation (H.E.L.P.) apheresis removes simultaneously circulating LDL, lipoprotein(a) [Lp(a)], fibrinogen, C-reactive protein (CRP) and various proinflammatory and procoagulatory factors. This study was to test the feasibility of H.E.L.P. apheresis in preeclamptic patients and its potential effects on blood and placental markers of preeclampsia. We applied H.E.L.P. apheresis to nine preeclamptic patients and it was well tolerated. Their gestational ages could be continued by 17.7 (3-49) more days. Eight of the nine neonates did well during their neonatal stage. One infant died of late-onset sepsis. H.E.L.P. apheresis reduced significantly circulating levels of triglycerides, total and LDL-cholesterol, Lp(a), fibrinogen, hs-CRP, TNFalpha, sVCAM-1, E-selectin, lipopolysaccharide binding protein (LBP), homocysteine and plasma viscosity. We conclude that H.E.L.P. apheresis reduced maternal circulating levels of proinflammatory and coagulatory markers and plasma viscosity without overt maternal or neonatal clinical side effects.

The placenta in pre-eclampsia and intrauterine growth restriction: studies on exchange surface areas, diffusion distances and villous membrane diffusive conductances

We test the null hypothesis that the morphometric diffusive conductance of the placental villous membrane does not alter in pregnancies complicated by intrauterine growth restriction (IUGR) or pre-eclampsia (PE). Placentas were collected from cases of normotensive IUGR, pure PE, PE+IUGR and from control pregnancies. Microscopical fields on formalin-fixed, trichrome-stained histological sections were randomly sampled for location and orientation. Using stereological methods, the exchange surface areas of peripheral (terminal and intermediate) villi and their fetal capillaries and the arithmetic and harmonic mean thicknesses of the villous membrane (maternal aspect of trophoblast to luminal aspect of vascular endothelium) were estimated. An index of the variability in thickness of this membrane, and an estimate of its oxygen diffusive conductance, was derived secondarily. Group comparisons were drawn using two-way analysis of variance to identify main effects (of PE or IUGR) and interaction effects (between PE and IUGR). PE did not have significant effects on placental morphology and there were no significant effects of PE or IUGR on membrane thickness or its variability. In contrast, IUGR (with or without PE) was associated with reduced surface areas and this was the principal factor leading to a smaller membrane diffusive conductance in these placentas. When account was taken of fetal mass, specific conductance showed no effects of PE or IUGR despite the mass-specific conductance in pure IUGR placentas appearing to be smaller than that in controls. The decline in total conductances is indicative of perturbations operating at the levels of villous trophoblast and fetal vasculature and these may contribute to fetal hypoxic stress.

Umbilical Cord Serum Activin A Levels are Increased in Pre-eclampsia with Impaired Blood Flow in the Uteroplacental and Fetal Circulation

The aims of the present study were to evaluate the umbilical cord serum activin A concentrations in complicated pregnancies and also to explore the relationship between activin A levels and blood flow velocity in fetal arteries. Umbilical cord blood samples were obtained postpartum after a full term uneventful gestation (control group, n=40), and from pregnancies complicated by gestational diabetes (n=13), preterm labour (n=18), or pre-eclampsia (n=19). Cord serum activin A levels were three-fold higher in pregnancies complicated by pre-eclampsia (1.17+/-0.14 ng/ml, p<0.01) than in the control group (0.43+/-0.03 ng/ml), but were unaltered in the diabetes and preterm labour groups. The pre-eclampsia group had a marked increase of umbilical artery pulsatility index (PI) and also a decrease of middle cerebral artery PI (p<0.01). Furthermore, activin A concentration correlated directly with the umbilical artery PI (r=0.540, p=0.021), with the length of stay in the Neonatal Intensive Care Unit (r=0.857, p<0.001) and also with cord blood pH (r=-0.886, p<0.001). In conclusion, umbilical cord serum activin A levels are increased in the presence of pre-eclampsia and provide an indirect marker of impaired blood flow in the uteroplacental and fetal circulation.

Uterine vein and maternal urinary levels of activin A and inhibin A in pre-eclampsia patients

OBJECTIVES

The aims of this study were to investigate if (i) urinary concentrations of activin A and inhibin A are altered in pre-eclampsia (PE) and (ii) to study the relationship between uterine vein and peripheral vein concentrations of these hormones in PE patients.

DESIGN AND METHOD

In a retrospective study, maternal peripheral vein and uterine vein serum and maternal urine samples collected at the time of delivery were analysed. There were three groups of patients; (i) group 1: term normal pregnancies (n = 19) (ii) group 2: patients who developed PE < or = 37 weeks (n = 17) and (iii) group 3: patients who developed PE 37-40 weeks (n = 8). Serum and urinary activin A, follistatin, inhibin A and pro alpha C and urinary creatinine levels were measured using enzyme immunoassays in the laboratory.

RESULTS

Normal pregnant urine samples had very low levels of activin A and inhibin A. Both groups 2 and 3 PE patients had significantly higher levels of inhibin A (P < 0.001) and activin A (P < 0.001) compared to the controls. Pro-alpha C was not altered and follistatin was below the detection limit of the assay in the urine. Maternal peripheral serum activin A and inhibin A were significantly higher in groups 2 (P < 0.001) and 3 (P < 0.05) patients compared to the controls. Pro-alpha C-containing inhibins were higher in group 2 patients (P < 0.05) compared to the controls in the peripheral circulation. Uterine vein serum activin A and inhibin A levels were also significantly higher in groups 2 (P < 0.001) and 3 (P < 0.05) patients compared to the controls. There was a highly significant positive correlation between peripheral and uterine vein serum concentrations of activin A, follistatin, inhibin A and pro alpha C, suggesting the same source for these proteins in PE.

CONCLUSION

Urinary activin A and inhibin A are raised in groups 2 and 3 PE patients. The magnitude of rise (> 25-fold) suggests these proteins may rise in patients before the onset of the clinical symptoms of PE. Uterine vein levels of these proteins are also raised in PE.

P-type inositol phosphoglycans in serum and amniotic fluid in active pre-eclampsia

OBJECTIVES

Abnormal secretion of P-type inositol phosphoglycans (IPG-P) has been described in maternal urine of pre-eclamptic women. The aim of this study was to determine the origin of production of IPG-P. We examined the IPG-P content of maternal and fetal serum, maternal urine and amniotic fluid in both normal pregnancy and pre-eclampsia.

DESIGN

Established extraction and bioactivity assay techniques were used to compare total IPG-P levels in serum samples, and a polyclonal-antibody-based ELISA to assay the amniotic fluid and urine samples in matched pairs of women.

SUBJECTS

Eleven women with pre-eclampsia requiring caesarean section (subjects), 11 pregnant women requiring elective caesarean section for reasons other than pre-eclampsia (controls).

RESULTS

Our data confirm the abnormal level of IPG-P in maternal urine during pre-eclampsia. Moreover, IPG-P levels were higher in umbilical sera than in maternal sera samples. Amniotic fluid as well as urine ELISA results were significantly higher in the pre-eclamptic group compared with normal controls. Total IPG-P bioactivity in serum did not vary between serum compartments in normal pregnancy. Uterine vein IPG-P levels were lower in pre-eclampsia when compared with normal pregnancy. A possible correlation was observed between urine and amniotic fluid levels in normal women. No correlation was observed between measured blood levels and those in urine and amniotic fluid.

CONCLUSIONS

It is hypothesized that steady state equilibrium of IPG-P in serum in normal pregnancy is disrupted in pre-eclampsia. Additionally, an abnormal IPG-P sub-fraction, detectable in urine and amniotic fluid, may be present and involved in the pathophysiology of the syndrome, although sites of production of this abnormal form remain unclear.

The role of placental oxidative stress and lipid peroxidation in preeclampsia

Preeclampsia is a complex multisystem disorder exclusively seen in human species that is characterized by hypertension and proteinuria. This disorder has the highest maternal and fetal morbidity and mortality of all pregnancy-related complications. Growing evidence suggests that placental oxidative stress is involved in the etiopathogenesis of preeclampsia. Reduced perfusion as a result of abnormal placentation leads to ischemia reperfusion injury to the placenta. Placental oxidative stress, which results from the ischemia reperfusion injury, is being increasingly reported to be involved in the etiopathogenesis of preeclampsia. It has been proposed as a promoter of lipid peroxidation and the endothelial cell dysfunction that is commonly seen in this condition. Although preeclampsia is characterized by increased lipid peroxidation and diminished antioxidant capacity, there is no consensus regarding causality of lipid peroxidation in preeclampsia. In this article, we address the question of the biologic association of lipid peroxidation and preeclampsia. Lipid peroxidation and leukocyte activation may play a pivotal role in endothelial cell dysfunction. We also review the different factors that have been proposed to cause endothelial cell dysfunction in preeclampsia, trials investigating the role of antioxidant supplementation in preeclampsia, and the lack of consensus among the trials. Additional longitudinal studies are necessary to determine if the various oxidative stress biomarkers estimated early in pregnancy can be narrowed to a single marker for predicting preeclampsia.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall that placental oxidative stress is involved in the etiopathogenesis of preeclampsia, state that placental oxidative stress results from ischemic reperfusion injury, and explain that ischemic reperfusion injury is a promoter of lipid peroxidation and endothelial cell dysfunction seen in preeclampsia.

Preeclampsia: the Death of Goliath

In this review, a novel and unifying pathophysiologic mechanism of preeclampsia is presented whereby a minimal excess of placental immune complex production versus removal causes a proinflammatory autoamplification cascade of trophoblast apoptosis/necrosis and oxidative stress, culminating in clinical preeclampsia. This concept immediately leads to a plethora of new and robust therapeutic strategies.

Neutrophil Function During Pregnancy: Is Nitric Oxide Production Correlated with Superoxide Production?

PROBLEM

Oxygen radical formation by neutrophils during pregnancy is not well studied.

METHOD OF STUDY

We studied neutrophil-derived superoxide anion (O) and nitric oxide (NO) values in 75 normal pregnant women, 12 postpartum women, and 10 non-pregnant women. O production was measured by the superoxide dismutase-inhibitable reduction of ferricytochrome c. NO production was measured by accumulation of the stable end product nitrite using a modified Griess reaction method.

RESULTS

O production of neutrophils stimulated by chemotactic peptide was significantly enhanced in the early second trimester of pregnancy. l-arginine analogue-inhibitable nitrite production was induced in neutrophils from pregnant women, but not from postpartum and non-pregnant subjects. In third-trimester subjects but not non-pregnant subjects, neutrophils pre-treated with l-arginine analogues enhanced O production compared with untreated neutrophils.

CONCLUSION

These findings indicate that O and NO production by neutrophils during pregnancy were modulated separately, whereas neutrophil-derived NO might function as a regulator of O.

Insulin resistance in human preeclamptic placenta is mediated by serine phosphorylation of insulin receptor substrate-1 and -2

CONTEXT

Preeclampsia is a severe complication of human pregnancy often associated with maternal risk factors. Insulin resistance represents a major risk for developing preeclampsia during pregnancy.

OBJECTIVE

A putative second messenger of insulin, inositol phosphoglycan P type (P-IPG), was previously shown to be highly increased during active preeclampsia. Its association with insulin resistance was investigated.

DESIGN AND SETTING

A cross-sectional study was carried out in a referral center.

PATIENTS

Nine preeclamptic (PE) and 18 healthy women were recruited and matched for maternal age, body mass index, parity, and ethnicity in a 1:2 ratio. Placental specimens were collected immediately after delivery.

INTERVENTION

Placental tissue was incubated with insulin and P-IPG production assessed. Insulin signaling proteins were subsequently studied by immunoblotting.

RESULTS

P-IPG extracted from human term placentas upon incubation with insulin was found to be far lower in those with preeclampsia than controls (P < 0.001). Immunoblotting studies revealed serine phosphorylation of insulin receptor substrate-1 and -2 in PE placentas (P < 0.001) with downstream impairment of insulin signaling. The activation of the p85 regulatory subunit of phosphatidylinositol 3- kinase was markedly decreased in PE samples (P < 0.001).

CONCLUSIONS

These findings highlight the importance of P-IPG in active preeclampsia and demonstrate a substantially different response to the insulin stimulus of human PE placentas. Acquired alterations in activation of proteins involved in insulin signaling may play a role in the complex pathogenesis of preeclampsia, probably as a consequence of the immunological dysfunction that occurs in this syndrome. These results seem to confirm an insulin-resistant state in PE placenta and shed a different light on its role in the pathogenesis of this disease with potential therapeutic implications.

Cytokine mapping of sera from women with preeclampsia and normal pregnancies

INTRODUCTION

Preeclampsia is a pregnancy-specific syndrome. The immune system in preeclampsia is changed with an increased innate activity and there is a hypothesis of a shift towards Th1-type immunity. The aim of this study was to determine a spectrum of soluble immunological factors denoting different aspects of immune activation in third trimester sera from women with preeclampsia (N=15) and compare with levels in sera from normal pregnant women (N=15).

MATERIAL AND METHODS

IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12 p40, IL-13, IL-15, IL-17, IFN-alpha, IFN-gamma, TNF-alpha, GM-CSF, MIP-lalpha, MIP-1beta, MCP-1, eotaxin and RANTES were measured in serum using multiplex bead arrays. The levels of soluble CD14 and soluble IL-4 receptor were measured by enzyme-linked immunoassay (ELISA).

RESULTS

Preeclamptic women had significantly increased levels of circulating IL-6 (p=0.002), IL-8 (p=0.003) and soluble IL-4R (p=0.037), compared to women with normal pregnancies.

CONCLUSION

This study supports the hypothesis of increased inflammatory responses in preeclampsia, illustrated by the increased levels of IL-6 and IL-8. The finding of increased levels of soluble IL-4 receptor is an intriguing finding with several interpretations, which may partly support the hypothesis of a Th1 shift in preeclampsia.

Three mechanisms in the pathogenesis of pre-eclampsia suggested by over-represented transcription factor-binding sites detected with comparative promoter analysis

Microarray studies generating lists of genes with altered expression in placentas from pregnancies complicated with pre-eclampsia (PE) have so far been published in several different studies. Working under the assumption that altered gene expression in PE may be the result of altered expression of regulatory transcription factors (TFs), we looked for over-represented TF-binding sites (TFBSs)-which indicate the involvement of TFs in gene regulatory networks-in lists of genes (n = 143) compiled in these studies. We compared the prevalence of TFBSs in the promoter regions of 68 genes with the background prevalence of TFBSs in promoters of the human genome. The prevalence of the E47, sterol regulatory element binding protein (SREBP) and NFKB-p50 TFBSs was higher (P < 0.005) in the promoter sequences of the PE gene lists than in the background model. Each of these TFBSs could be implicated in the development of PE. The E47 protein is an E-protein or basic helix-loop-helix (bHLH) TF. Data support the role of bHLHs in the differentiation of placental tissue. SREBP-1, a lipid-sensing sterol regulatory element-binding protein, is a critical regulator of fatty acid homeostasis in the placenta. The target genes of NFKB-p50 determine inflammatory response, and aberrant cytokine homeostasis is a further sign of PE. These TFs may provide an insight into the pathogenesis of the disease.

Future directions of failed implantation and recurrent miscarriage research

Recurrent implantation failure is today the major reason for women completing several IVF/intracytoplasmic sperm injection attempts without having achieved a child, and is probably also the explanation for many cases of unexplained infertility. Most causes of recurrent miscarriage are still poorly elucidated, but from a theoretical point of view recurrent implantation failure and recurrent miscarriage are suggested to have partly overlapping causes. Recent research has indeed documented that both syndromes can be caused by the same embryonic chromosomal abnormalities and the same maternal endocrine, thrombophilic and immunological disturbances. Consequently, many treatments attempting to normalize these abnormalities have been tested or are currently used in women with both recurrent implantation failure and recurrent miscarriage. However, no treatment for the two syndromes is at the moment sufficiently documented to justify its routine use. In this review, an overview is given regarding present knowledge about causes that may be common for recurrent implantation failure and recurrent miscarriage, and suggestions are put forward for future research that may significantly improve understanding and treatment options for the syndromes.

Syncytiotrophoblast micro-particles do not induce apoptosis in peripheral T lymphocytes, but differ in their activity depending on the mode of preparation

Recent studies have suggested that pre-eclampsia may result from endothelial cell damage and overt immune activity triggered by the elevated release of syncytiotrophoblast-derived micro-particles (STBM). In this context, STBM have been reported to inhibit lymphocyte proliferation and induce Jurkat T cell apoptosis. In this study, STBM were prepared by three different in vitro methods (mechanical dissection, villous explant culture, and placental perfusion) and their functional properties were tested on T lymphocytes enriched from peripheral blood samples. Mechanically- and villous explant-derived STBM significantly inhibited activation, proliferation and cytokine release by T lymphocytes, while placental perfusion-derived STBM significantly induced T cell proliferation and a slight increase in IFNgamma release. None of the STBM preparations caused T cell apoptosis. Therefore, STBM prepared by different methods in vitro exhibit different effects on circulating T cells, a feature that will have to be taken into account when considering their potential role in normal pregnancy and pre-eclampsia.

Changes in systemic type 1 and type 2 immunity in normal pregnancy and pre-eclampsia may be mediated by natural killer cells

A bias of T cell immunity towards type 2 (Th2) is thought to be critical for normal pregnancy. Pathological pregnancies, such as pre-eclampsia, are characterised by cell-mediated (Th1) immune dominance. The Th1/Th2 paradigm, however, is too simplistic. Normal pregnancy is associated with a systemic inflammatory response which increases throughout gestation. This inflammatory response is exaggerated in pre-eclampsia, a syndrome of the third trimester. T helper (Th) cells are considered the primary mediators of these altered immune responses, and other T cells, i.e. T cytotoxic (Tc) cells, and lymphocytes of the innate immune system, i.e. natural killer (NK) and NKT cells, have been largely disregarded. In this study, we have used novel pan type 1 (IL-18 receptor) and pan type 2 (ST2L) lymphocyte function markers in four-colour flow cytometry to broadly characterise peripheral blood lymphocyte populations from non-pregnant, normal pregnant and pre-eclamptic women. There were no changes in the Th1/Th2 or Tc1/Tc2 cell ratios between the three groups; however, the NK1/NK2 and NKT1/NKT2 cell ratios were significantly decreased in normal pregnancy compared with non-pregnant (p <0.001 and p <0.01, respectively) and pre-eclamptic women (p <0.05). These results confirm that immunoregulation occurs in pregnancy, but suggest a dominant role of the innate rather than the adaptive immune system.

Protein Z in patients with pregnancy complications

OBJECTIVE

This study was undertaken to evaluate the association between protein Z concentration and pregnancy complications.

STUDY DESIGN

A prospective case-control study was conducted over a 2-year period to evaluate the prevalence of protein Z deficiency in pregnancy complications. Protein Z levels were measured at the time of diagnosis of complications such as preeclampsia, intrauterine growth restriction, and intrauterine fetal demise. Protein Z deficiency was defined as a plasma level below 1.2 mg/L. In addition to patients presenting with pregnancy complications, healthy age-matched nonpregnant and pregnant women were invited to participate.

RESULTS

A total of 145 women were included in the study: 50 nonpregnant women, 34 healthy pregnant women, 29 women with preeclampsia, 25 women presented with intrauterine growth restriction, and 7 women with intrauterine fetal demise. The median protein Z level was similar in healthy pregnant and nonpregnant women (1.63 [0.47-3.1] mg/L and 1.69 [0.7-3] mg/L, respectively). Three women with normal pregnancies had a low protein Z level (8.8%), compared with 8 patients presenting with intrauterine growth restriction (33.3%) and 8 patients with intrauterine fetal demise (50%). Compared with normal pregnancy, the frequency of decreased protein Z was significantly higher in cases of intrauterine growth restriction and in intrauterine fetal demise (relative risk [RR] 1.96, 95% CI 1.16-3.32; P = .041 and RR 3.36, 95% CI 1.65-6.8; P = .0031, respectively), but not in preeclampsia (RR 1.6, 95% CI 0.9-2.8; P = .23). Placenta histologic examination revealed vascular lesions in 50% of patients with protein Z deficiency and in 33% of patients with normal levels of protein Z (RR 0.84; 95% CI 0.6-1.2).

CONCLUSION

Protein Z deficiency is associated with late fetal demise and intrauterine growth restriction. The pathophysiologic role of protein Z deficiency, either congenital or caused by the presence of specific antibodies remains unclear and should be further investigated.

Regulation of the endothelin/endothelin receptor system by interleukin-1{beta} in human myometrial cells

Proinflammatory cytokines produced at the fetomaternal interface, such as IL-1beta, have been implicated in preterm and term labor. The present study was performed to evaluate the influence of IL-1beta on the endothelin (ET)/ET receptor system in human myometrial cells. We report that myometrial cells under basal conditions not only respond to but also secrete ET-1, one of the main regulators of uterine contractions. Prolonged exposure of the cells to IL-1beta led to a decrease in prepro-ET-1 and ET-3 mRNA correlated with a decrease in immunoreactive ET-1 and ET-3 levels in the culture medium. Whereas ETA receptor expression at both protein and mRNA levels was not affected by IL-1beta treatment, we demonstrated an unexpected predominance of the ETB receptor subtype under this inflammatory condition. Whereas the physiological function of ETB remains unclear, we confirmed that only ETA receptors mediate ET-1-induced myometrial cell contractions under basal conditions. By contrast, prolonged exposure of the cells to IL-1beta abolished the contractile effect induced by ET-1. Such a regulation of IL-1beta on the ET release and the balance of ETA to ETB receptors leading to a loss of ET-1-induced myometrial cell contractions suggest that complex regulatory mechanisms take place to constraint the onset of infection-induced premature contractions.

The impact of maternal HBsAg carrier status on pregnancy outcomes: a case-control study

BACKGROUND/AIMS

To examine the impact of maternal HBsAg carrier status on pregnancy outcomes.

METHODS

Two hundred and fifty-three carriers of hepatitis B surface antigen (HBsAg) with singleton pregnancy, were retrospectively compared with 253 controls matched for age and parity and year of delivery.

RESULTS

On univariable analysis, HBsAg carriers had higher incidences of threatened preterm labour at <37 weeks (11.9% vs. 6.3%, P=0.030), preterm birth at <34 weeks (4.7% vs. 1.2%, P=0.033), gestational diabetes mellitus (19.0% vs. 11.1%, P=0.012) and antepartum haemorrhage (11.5% vs. 5.5%, P=0.026). Their infants had lower Apgar scores at the 1st (8.47+/-1.67 vs. 8.87+/-1.07, P=0.001) and 5th minute (9.56+/-1.29 vs. 9.80+/-0.54, P=0.007), and increased incidence of intraventricular haemorrhage (4.7% vs. 0.8%, P=0.007). On multivariable analysis, the association between HBsAg carrier state with antepartum haemorrhage, gestational diabetes mellitus and threatened preterm labour were confirmed.

CONCLUSIONS

HBsAg carriers have increased risk of gestational diabetes mellitus, antepartum haemorrhage, and threatened preterm labour. This may be related to the chronic inflammatory state in these subjects. The role of chronic HBV infection in pregnancy complications has to be further elucidated.

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.

Spinal anesthesia-induced hypotension: a risk comparison between patients with severe preeclampsia and healthy women undergoing preterm cesarean delivery

We previously showed that, in comparison with term healthy parturients, patients with severe preeclampsia had a less frequent incidence of spinal hypotension, which was less severe and required less ephedrine. In the present study, we hypothesized that these findings were attributable to preeclampsia-associated factors rather than to a smaller uterine mass. The incidence and severity of hypotension were compared between severe preeclamptics (n = 65) and parturients with preterm pregnancies (n = 71), undergoing spinal anesthesia for cesarean delivery (0.5% bupivacaine, sufentanil, morphine). Hypotension was defined as the need for ephedrine (systolic blood pressure <100 mm Hg in parturients with preterm fetuses or 30% decrease in mean blood pressure in both groups). Apgar scores and umbilical arterial blood pH were also studied. Neonatal and placental weights were similar between the groups. Hypotension was less frequent in preeclamptic patients than in women with preterm pregnancies (24.6% versus 40.8%, respectively, P = 0.044). Although the magnitude of the decrease in systolic, diastolic, and mean arterial blood pressure was similar between groups, preeclamptic patients required less ephedrine than women in the preterm group to restore blood pressure to baseline levels (9.8 +/- 4.6 mg versus 15.8 +/- 6.2 mg, respectively, P = 0.031). The risk of hypotension in the preeclamptic group was almost 2 times less than that in the preterm group (relative risk = 0.603; 95% confidence interval, 0.362-1.003; P = 0.044). The impact of Apgar scores was minor, and umbilical arterial blood pH was not affected. We conclude that preeclampsia-associated factors, rather than a smaller uterine mass, account for the infrequent incidence of spinal hypotension in preeclamptic patients.

Generation of reactive oxygen species by neutrophils and endothelial cell injury in normal and preeclamptic pregnancies

The aim of this study was to investigate the role of neutrophil-derived reactive oxygen species on endothelial cell dysfunction in preeclampsia. We first assessed the correlation between nitrite and superoxide anion production in normal nonpregnant (n=10), normal pregnant (n=15), and preeclamptic women (n=12). We then examined neutrophil-mediated oxygen radical damage to human umbilical vein endothelial cells in vitro. Neutrophil superoxide release was measured by cytochrome C reduction; nitrite release was measured by the modified Griess reaction, and endothelial cell injury was measured by 51Cr release. N-formyl-methionyl-leucyl-phenylalanine-stimulated superoxide release by neutrophils was significantly increased in women with preeclampsia compared with the other 2 groups. Nitrite release by neutrophils was significantly decreased in preeclampsia compared with normal pregnancy. When neutrophils were pretreated with superoxide dismutase, nitrite release by neutrophils did not differ between normal pregnancy and preeclampsia, suggesting that excess superoxide anion in preeclampsia could reduce bioavailability of nitric oxide through neutrophil autocrine function. Neutrophil-mediated endothelial cell injury was significantly greater in women with preeclampsia than in the other 2 groups. Hydrogen peroxide was important in neutrophil-mediated endothelial cell injury in preeclampsia as catalase inhibited endothelial cell injury. When neutrophils were pretreated with NG-nitro-L-arginine methyl ester, neutrophil-mediated endothelial cell injury in preeclampsia was decreased, indicating a role for peroxynitrite formation as a mechanism of endothelial cell injury. In conclusion, the modulation of neutrophils causing superoxide production to dominate over nitrite release provides a reasonable explanation for endothelial cell dysfunction in preeclampsia.

Latest advances in understanding preeclampsia

Preeclampsia is a relatively common pregnancy disorder that originates in the placenta and causes variable maternal and fetal problems. In the worst cases, it may threaten the survival of both mother and baby. We summarize recent work on the causes of preeclampsia, which reveals a new mode of maternal immune recognition of the fetus, relevant to the condition. The circulating factors derived from the placenta, which contributes to the clinical syndrome, are now better understood. This brief review on preeclampsia does not cover all aspects of this intriguing condition but focuses on some new and interesting findings.

Mice with a severe deficiency in protein C display prothrombotic and proinflammatory phenotypes and compromised maternal reproductive capabilities

Anticoagulant protein C (PC) is important not only for maintenance of normal hemostasis, but also for regulating the host immune response during inflammation. Because mice with a designed total genetic deficiency in PC (PC-/- mice) die soon after birth, attempts to dissect PC function in various coagulation/inflammation-based pathologies through use of mice with less than 50% of normal PC levels have not been successful to date. In the current investigation, we have used a novel transgenic strategy to generate different mouse models expressing 1-18% of normal PC levels. In contrast to PC-/- mice, mice with only partial PC deficiency survived beyond birth and also developed thrombosis and inflammation. The onset and severity of these phenotypes vary significantly and are strongly dependent on plasma PC levels. Our findings additionally provide the first evidence that maternal PC is vital for sustaining pregnancy beyond 7.5 days postcoitum, likely by regulating the balance of coagulation and inflammation during trophoblast invasion. These low PC-expressing transgenic mouse lines provide novel animal models that can be used to elucidate the importance of PC in maintenance of the organism and in disease.

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.

Relationships between perinatal and maternal characteristics and hepatoblastoma: a report from the UKCCS

Within the context of a national population-based case-control study--the United Kingdom Childhood Cancer Study (UKCCS)--we aimed to explore relationships between perinatal and maternal factors and childhood hepatic tumours, for participants with data available from medical records. 26/28 children with hepatic tumours (22/24 hepatoblastomas, 4/4 hepatocellular carcinomas (HCC)) and 4753 age- and sex-matched controls were included. Polyhydramnios was associated with 0.9% of control pregnancies and 13.6% of case pregnancies (Odds Ratio (OR)=28.64, 95% Confidence Interval (CI)=6.94-118.21, P<0.0001); eclampsia or severe pre-eclampsia complicated the pregnancies of 16.7% of mothers whose children developed hepatoblastoma compared with 0.5% of control pregnancies (OR=52.50, 95% CI=10.75-257.05, P<0.0001). Three children with hepatoblastoma weighed <1500 g at birth, two of whom weighed <1000 g (OR for birthweight <1500 g=69.00, 95% CI=11.98-397.17, P<0.0001). Of children with hepatoblastoma, 50% (11/22) had records of congenital anomalies, as did two of their mothers. Three mothers of children with hepatoblastoma had diagnoses of cancer--two of papillary carcinoma of the thyroid and one of acute lymphoblastic leukaemia (ALL). Paediatricians and others should be alert to the possibility of familial or genetic syndromes in children with hepatoblastomas. Potential links between maternal pre-eclampsia, low birthweight and subsequent malignancy merit further investigation. Hepatoblastoma is an extremely rare childhood tumour, but understanding the mechanism(s) underlying severe pre-eclampsia and eclampsia may also shed light on factors that contribute to the development of hepatoblastoma.

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.

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.

Perinatal and reproductive factors: a report on haematological malignancies from the UKCCS

The United Kingdom Childhood Cancer Study was designed to examine the potential aetiological role of a range of perinatal and reproductive factors. Our use of clinical records permitted a more exact characterisation of reproductive events than is possible in investigations that rely on self-reporting; and the increased specificity with which antecedent events were measured produced more precise risk estimates, albeit ones based on progressively smaller numbers. Information on the conduct of this component of the study and results for 1485 children with haematological malignancies and 4864 controls are presented. The 'find' rate for obstetric records was high at 86% for cases, with 81% having information on both matched controls. Associations were seen for severe hyperemesis (Odds Ratio=3.6, 95%Confidence Interval=1.3-10.1, for all leukaemias), polyhydramnios (OR=4.0, 95%CI=1.5-10.3, for acute myeloid leukaemia (AML)), anaemia (haemoglobin <10 g, OR=2.6, 95%CI=1.7-4.1, for AML), and pre-eclampsia (OR=1.7, 95%CI=1.1-2.7, for non-Hodgkin's lymphoma). Babies who developed leukaemia were heavier at birth (>4000 g, OR=1.2, 95%CI=1.0-1.4), as were their older siblings (>4000 g, OR=1.4, 95%1.0-1.9). Mothers' whose children developed common B-cell precursor acute lymphoblastic leukaemia (ALL) were more likely to have had a previous molar pregnancy (OR=5.2, 95%CI=1.9-14.7). Gender-specific analysis revealed that findings often differed markedly for boys and girls; and, in common with other reports, strong associations with Down's syndrome were seen for both ALL and AML.

The twin placenta: framework for gross analysis in fetal origins of adult disease initiatives

Current data strongly support that a wide variety of adult health risks are influenced by intrauterine life events. Twins may have the same (identical, monozygous) or different (fraternal, dizygous) genes, but their relationship to their outside world, via their placentas, is rarely equal. Monochorionic twins and dichorionic twins both resemble and differ from singletons. In the balance between the similarities and the differences, we may find the answer to the interpretation of twin studies, and appropriately apply them to the 'fetal origins' hypothesis.

Placental villitis of unknown origin: epidemiologic associations

OBJECTIVES

This study was undertaken to investigate the incidence and associations of placental villitis of unknown origin or etiology (VUE).

STUDY DESIGN

Five hundred nine placentas from women delivered of small-for-gestational-age infants (SGAP) and 529 placentas from women delivering infants with birth weights appropriate for gestational age (AGAP) were examined prospectively for VUE as part of a population-based case control study of SGA infants at term.

RESULTS

VUE was found in 17.3% of SGAP and 11.7% of AGAP and was an independent risk factor for SGA (adjusted odds ratio 2.35, 95% CI 1.55-3.56). Villitis in conjunction with maternal hypertension increased the risk of SGA substantially (adjusted odds ratio 17.7, 95%CI 3.6-86.9). A study of a wide range of pregnancy-related factors found no significant associations with VUE in AGAP. In contrast, VUE in SGAP had significant associations after multivariate analysis with maternal body mass index, multigravidity, ethnicity, and 1 index of maternal infection.

CONCLUSION

VUE is an independent risk factor for SGA at term. Maternal factors influence this association, possibly by modifying a systemic effect on fetal growth of villous inflammation at commonly occurring defects in the maternal-fetal immune barrier.

Activating auto-antibodies against the AT1 receptor in preeclampsia

Immune mechanisms have been shown to be important in the pathogenesis of preeclampsia. Here, we review our studies of agonistic antibodies against the AT1 receptor in the pathogenesis as well as a pathologic phenotype of this disorder, focusing on observations in our laboratory. We have demonstrated their specificity of the binding by Western blotting, co-localization, and co-immunoprecipitation experiments. AT1-AA induce signaling in vascular cells and trophoblasts including AP-1 and nuclear factor-kappaB (NF-kappaB) activation. The signaling results in tissue factor production and reactive oxygen species (ROS) 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 proven with certainty. However, we believe the findings are compelling and warrant further study.

A comparative study of the effect of three different syncytiotrophoblast micro-particles preparations on endothelial cells

Pre-eclampsia is a pregnancy-associated multi-system disorder of unknown etiology, characterized by damage to the maternal endothelium. The latter facet has been suggested to be mediated in part by elevated shedding of inflammatory placental syncytiotrophoblast micro-particles (STBM) into the maternal circulation. In this study, we have examined STBM prepared by three different methods: mechanical dissection, in vitro placental explant culture and perfusion of placental cotyledons. All three preparations yielded morphologically similar STBM, as confirmed by scanning electron microscopy, and all contained syncytiotrophoblast-specific proteins as determined by the presence of placental alkaline phosphatase. The functional properties of the three STBM preparations were examined on human umbilical vein endothelial cells (HUVEC), where the mechanically prepared particles were found to inhibit proliferation to the greatest extent. Furthermore, only mechanically prepared STBM lead to the detachment and apoptosis of HUVEC cells. Our study, therefore, suggests that STBM prepared from placental perfusion or in vitro explant culture are biologically different from mechanically prepared ones, and may provide a better approximation of physiologically produced placental micro-particles.