The cell adhesion molecule, VCAM-1, is selectively elevated in serum in pre-eclampsia: does this indicate the mechanism of leucocyte activation?

Does endothelial cell activation occur with intrauterine growth restriction?

It is possible that in fetal growth restriction without pre-eclampsia endothelial cell activation does not occur. This might be either because there is no release of 'factor X' or because of maternal resistance to its effects. To test this hypothesis, we took blood samples from 26 women with pre-eclampsia (without fetal growth restriction), 13 women with fetal growth restriction (without pre-eclampsia) and 24 normal pregnant controls, and measured the circulating levels of three markers of endothelial cell activation (soluble VCAM, ICAM and E-selectin) and three cytokines [tumour necrosis factor-a (TNF-alpha), interleukin-6 (IL-6) and -8 (IL-8)]. The levels of the markers of endothelial cell activation were raised in both pre-eclampsia and fetal growth restriction pregnancies compared with controls; however, the levels of TNF-alpha, IL-6 and IL-8 were significantly raised in pregnancies complicated by pre-eclampsia, but not in fetal growth restriction, compared with controls. These data show that endothelial cell activation is common to both pre-eclampsia and fetal growth restriction, but that the circulating levels of cytokines are elevated only in pre-eclampsia. Thus, it seems likely that endothelial cell activation is a consequence of a failure of trophoblast invasion and that a further step is required, possibly involving cytokine release, for the expression of the full clinical picture of pre-eclampsia.

Soluble adhesion molecule profile in normal pregnancy and pre-eclampsia

OBJECTIVE

An exaggerated inflammatory response has been implicated as the cause of endothelial cell dysfunction and the maternal syndrome of pre-eclampsia. Adhesion molecules play a central role in the adherence of leukocytes to endothelial cells and the subsequent migration of white blood cells into perivascular tissue. Cellular forms of adhesion molecules mediate specific steps of leukocyte-endothelial cell interaction, and have been implicated in the pathophysiology of preeclampsia. Soluble forms of these molecules can be detected in plasma, and their concentrations are thought to reflect the degree of activation of a particular cell type. Elevations in soluble P-selectin (sP-selectin) reflect platelet activation; changes in soluble L-selectin (sL-selectin) suggest leukocyte activation; and an increase in soluble forms of E-selectin (sE-selectin), vascular cell adhesion molecule 1 (sVCAM-1), intercellular adhesion molecule 1 (sICAM-1) and platelet endothelial cell adhesion molecule (sPECAM-1) indicate endothelial cell activation/dysfunction. The objective of this study was to determine whether normal pregnancy and pre-eclampsia were associated with changes in the concentrations of soluble selectins and members of the immunoglobulin superfamily of adhesion molecules.

STUDY DESIGN

A cross-sectional study was conducted to determine the plasma concentrations of sL-selectin, sE-selectin, sP-selectin, sVCAM-1, sICAM-1 and sPECAM-1 in peripheral blood obtained from non-pregnant women (n = 20), normal pregnant women (n = 100) and patients with pre-eclampsia (n = 55). Concentrations of soluble adhesion molecules were determined with enzyme-linked immunoassays. Parametric statistics were used for data analysis.

RESULTS

Normal pregnancy was associated with a significant increase in the maternal plasma concentration of sP-selectin, a decrease in sL-selectin, and no change in sE-selectin, sVCAM-1, sICAM-1 and sPECAM-1. In contrast, pre-eclampsia was associated with a significant increase in sP-selectin, sE-selectin and sVCAM-1, a decrease in sL-selectin, but no change in sICAM-1 and sPECAM-1 concentrations.

CONCLUSIONS

The increased concentration of sP-selectin and decreased sL-selectin, as well as the lack of change in endothelial cell-associated soluble adhesion molecules suggest that pregnancy is associated with platelet and leukocyte activation, but not endothelial cell activation. In contrast, pre-eclampsia appears to be characterized by activation of platelets, leukocytes and endothelial cells.

Soluble adhesion molecules: marker of pre-eclampsia and intrauterine growth restriction

OBJECTIVE

This study monitored circulating plasma levels of soluble vascular cellular adhesion molecule-1 (sVCAM-1), intracellular adhesion molecule-1 (sICAM-1) and soluble E-selectin (sE-selectin) in women with healthy pregnancies, with pregnancy-induced hypertension (PIH), with pre-eclampsia and with pregnancies with isolated intrauterine growth restriction (IUGR) in order to determine whether elevated concentrations have a predictive value for the clinical signs of those pregnancy-induced disorders.

METHODS

Plasma concentrations of sVCAM-1, sICAM-1 and sE-selectin were determined in healthy pregnant women at each trimester of pregnancy and in pregnant women with PIH, pre-eclampsia and IUGR using commercial kits.

RESULTS

In the group of healthy pregnant women, plasma levels of sVCAM-1, sICAM-1 and sE-selectin did not change throughout pregnancy. No significant differences in the levels of these molecules were observed between healthy pregnant women at the third trimester of pregnancy and women with PIH. In addition, concentrations of soluble adhesion molecules were significantly higher in women with pre-eclampsia than in the group of women with healthy pregnancies. Only sVCAM-1 and sE-selectin levels were significantly higher in women with IUGR compared to healthy pregnant women.

CONCLUSIONS

Abnormally circulating levels of sVCAM-1, sICAM-1 and sE-selectin may have a predictive value for pre-eclampsia and IUGR, as they may be linked with endothelial activation and/or damage.

Effects of nicotine on intercellular adhesion molecule expression in endothelial cells and integrin expression in neutrophils in vitro

OBJECTIVE

We previously reported that nicotine decreases leukocyte adhesion to uterine vascular endothelial cells in vivo under ischemic conditions in pregnant rabbits. To further investigate the mechanism of decreased leukocyte-endothelial adhesion by nicotine exposure, the effect of nicotine on endothelial cell intercellular adhesion molecule expression and neutrophil integrin expression of CD62L, CD11a, and CD11b were examined.

STUDY DESIGN

Endothelial cells were isolated from human umbilical cord veins from normal pregnancies in nonsmoking women immediately after delivery. Neutrophils were isolated from healthy nonpregnant and nonsmoking female volunteers. First passage of endothelial cells and fresh isolated neutrophils were exposed to nicotine at different concentrations. Surface adhesion molecule expression of intercellular adhesion molecule on endothelial cells was determined by colorimetric assay. Neutrophil integrin expressions for CD62L, CD11a, and CD11b were determined by flow cytometry. Messenger RNA expression for intercellular adhesion molecule in endothelial cells was examined by reverse transcription-polymerase chain reaction.

RESULTS

Nicotine at a lower concentration of 0.01 micromol/L had no effect on endothelial cell surface intercellular adhesion molecule expression compared with controls (P =.614). Nicotine at a higher concentration of 10 micromol/L completely inhibited endothelial cell surface intercellular adhesion molecule-1 expression(P <.0001). At concentrations between 0.10 and 10 micromol/L, nicotine inhibited intercellular adhesion molecule expression in a dose-dependent manner. Messenger RNA expression of intercellular adhesion molecule in endothelial cells was not changed after exposure to nicotine. Decreased integrin expressions of CD62L, CD11a, and CD11b were observed on neutrophils after exposure to nicotine.

CONCLUSION

Nicotine exerts inhibitory effects on both endothelial cell surface intercellular adhesion molecule expression and neutrophil integrin expressions of CD62L, CD11a, and CD11b in vitro. These in vitro effects of nicotine may relate to the clinical observation of reduced incidence of preeclampsia in women that smoke.

Maternal endothelial soluble cell adhesion molecules with isolated small for gestational age fetuses: comparison with pre-eclampsia

OBJECTIVE

1. To evaluate the activation profile of the endothelium in pregnancies complicated by small for gestational age fetuses compared with pre-eclampsia and normal pregnancy, by measuring the plasma levels of soluble adhesion molecules soluble E-selectin, intercellular cell adhesion molecule-1 and vascular cell adhesion molecule-1. 2. To determine whether soluble adhesion molecules were related to the severity of small for gestational age fetuses and pre-eclampsia.

DESIGN

Observational study.

PARTICIPANTS

Sixteen women with small for gestational age fetuses; 15 women with pre-eclampsia and 15 healthy primigravidae were recruited as controls.

METHODS

Plasma levels of soluble E-selectin, intercellular cell adhesion molecule-1 and vascular cell adhesion molecule-1 were measured by ELISA.

RESULTS

Compared with the healthy controls, soluble E-selectin was significantly increased in both small for gestational age fetuses and pre-eclampsia, whereas intercellular cell adhesion molecule-1 and vascular cell adhesion molecule-1 were increased only in pre-eclampsia. In the small for gestational age fetuses group, soluble E-selectin correlated inversely with the ratio between birthweight and the expected normal birthweight (r = -0.4, P = 0.007). In the pre-eclampsia group, a significant correlation was observed between vascular cell adhesion molecule-1 and blood pressure (r = 0.54, P = 0.039).

CONCLUSIONS

Endothelial activation, reflected by raised levels of soluble E-selectin, is a feature of small for gestational age fetuses and is correlated with the severity of the disease. Differences in the profile of soluble cell adhesion molecules suggest variations in the degrees of endothelial activation between pre-eclampsia and small for gestational age fetuses.

Neutrophil oxygen radical production in pre-eclampsia with HELLP syndrome

OBJECTIVE

To determine whether severe pre-eclampsia complicated by hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome alters neutrophil oxygen radical production.

MATERIALS AND METHODS

Neutrophils were obtained from 10 healthy non-pregnant, 9 normal pregnant and 9 women with severe pre-eclampsia with concurrently HELLP syndrome. Oxygen radical production was evaluated using luminol-enhanced chemiluminescence and measured by cytochrome C reduction. Furthermore we incubated sera from cases and controls with isolated healthy neutrophils and measured their capacity to generate oxygen radicals.

RESULTS

Unstimulated neutrophil oxygen radical production was significantly lower in severe pre-eclamptics compared with healthy non-pregnant and pregnant subjects, whereas phorbol ester-induced oxygen radical production did not differ among categories. Cytochrome C reduction of unstimulated neutrophils showed similar results. Healthy neutrophils incubated with sera from pre-eclamptics enhanced the oxygen radical production significantly more than neutrophils incubated with sera from the healthy subjects.

CONCLUSIONS

Severe pre-eclampsia is characterised by decreased unstimulated neutrophil oxygen radical production. This may be the result of an exhausted cellular response due to stimulation by a factor present in the serum of these patients.

Androgen levels of preeclamptic patients in the third trimester of pregnancy and six weeks after delivery

BACKGROUND

The aim of this study was to measure the circulating levels of androgens in the third trimester of pregnancy and six weeks after delivery and to discuss androgen contribution in the pathogenesis of preeclampsia.

METHODS

Twenty-two preeclamptic and 20 normotensive women completed this prospective study. Blood samples were drawn in the third trimester (28-32 gestational weeks) and six weeks after delivery. Serum total testosterone (T), free testosterone (fT) dehydroepiandrosterone sulfate (DHEAS), androstenodione (A), sex hormone binding globulin (SHBG) and estradiol (E2) levels were measured. The statistical analyses of the data were performed by using Wilcoxon Rank test within the groups, Student unpaired t test and Chi-square test between the groups with the SPSS program.

RESULTS

T and fT levels were found to be significantly higher (p<0.05) in preeclamptic women in the third trimester compared to the values of normotensive controls. However, there were significant decreases (p<0.05) in T and fT levels six weeks after delivery, reaching values not significantly different from normotensive subjects (p>0.05). Furthermore, SHBG, DHEAS, A and E2 levels were not significantly different (p>0.05) between the groups in the third trimester or six weeks after delivery.

CONCLUSION

We conclude that higher blood androgen levels measured in preeclamptic patients may be implicated in the pathogenesis of preeclampsia.

The relationship between the level of expression of intercellular adhesion molecule-1 in placenta and onset of preeclampsia

OBJECTIVE

To investigate the differences in the expression of intercellular adhesion molecule-1 (ICAM-1) in the placenta and the concentration of soluble ICAM-1 between early-onset and late-onset preeclampsia.

METHODS

Preeclampsia was divided into early-onset type (EO: 20 to 31 weeks gestation) and late-onset type (LO: > or = 32 weeks gestation). Post delivery, placentas were obtained from 19 control pregnant women and from 9 EO and 8 LO preeclamptic women. The expression of ICAM-1 in placenta was determined by immunohistochemical staining. Blood samples were taken from 21 non-pregnant women, 16 control pregnant women, 13 EO and 8 LO preeclamptic women, and umbilical cord blood samples from 38 control pregnancies and from 16 EO and 14 LO preeclampsia. The concentration of ICAM-1 was measured by enzyme-linked immunosorbent assays.

RESULTS

The expression of ICAM-1 in placenta was higher in LO than in EO preeclampsia (48.2 +/- 8.2% vs 17.9 +/- 5.0%) (p < 0.05). ICAM-1 concentration in umbilical cord blood was higher in EO than in LO preeclampsia (umbilical artery, 150.6 +/- 34.0 ng/ml vs 90.3 +/- 9.4 ng/ ml) (umbilical vein, 128.3 +/- 31.2 ng/ml vs 91.3 +/- 10.2 ng/ml) (p < 0.05).

CONCLUSIONS

Significant differences were noted in the expression of ICAM-1 between patients with EO and LO preeclampsia, which suggest that the possibility that EO and LO preeclampsia may have different onset mechanisms.

Deficient detoxifying capacity in the pathophysiology of preeclampsia

An imbalance between oxidative stress and maternal detoxification or antioxidant capacity may explain the symptoms of preeclampsia and the haemolysis-elevated liver enzymes-low platelets (HELLP) syndrome. Oxidative stress is known to induce damage of the endothelium, which is one of the pathophysiological features of preeclampsia and the HELLP syndrome. Administration of N-acetylcysteine, an antioxidant itself and a precursor of the endogenous antioxidant glutathione, might stabilize or even partly recover the process of endothelial damage and may lead to prolongation of pregnancy.

Pregnancy, vascular tone, and maternal hemodynamics: a crucial adaptation

The adaptation of vascular tone in early pregnancy precedes and probably triggers blood volume and cardiac output increase. Because the endothelium is known to regulate vascular smooth muscle action, the role of nitric oxide (NO) in the setting up of adequate uteroplacental and renal blood flow during normal pregnancy was investigated. The persistence of abnormally high uteroplacental resistance is a strong predisposing factor for intrauterine growth retardation and preeclampsia and can be screened by second trimester Doppler assessment of the uterine arteries. Current hypotheses suggested by experimental and clinical data concerning preeclampsia confirm the crucial role played by the endothelium and vascular tone adaptation. The analysis of these data leads to consider apart early-onset preeclampsia affecting pregnancies with growth retarded fetuses and associated with high vascular resistance. Lastly, NO donors seem to significantly decrease the impedance in the uteroplacental circulation and to improve fetoplacental hemodynamics assessed by Doppler measurements, and their therapeutic use in some forms of preeclampsia might be promising.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader will be able to summarize the events that regulate vascular tone in pregnancy, specifically the role of nitric oxide and other vasoactive prostaglandins in the regulation of vascular tone and to describe the various hypotheses concerning the mechanism and the mediators responsible for initiating endothelial damage in the various disorders of vascular tone in pregnancy.

Correlation between placental bed biopsy findings, vascular cell adhesion molecule and fibronectin levels in pre-eclampsia

OBJECTIVE

To determine the correlation between placental bed biopsy findings, and blood levels of the vascular cell adhesion molecule (VCAM-1) and fibronectin in pre-eclampsia/eclampsia, and to evaluate the relationship between these variables and severity of the disease.

DESIGN

A prospective case-control study.

SETTING

Department of Obstetrics and Gynaecology, Cerrahpasa Medical Faculty, Istanbul.

SAMPLE

Thirty-five women with pre-eclampsia/eclampsia were compared with 25 healthy women with uncomplicated pregnancies. Twenty-one placental bed biopsies from pre-eclamptic pregnancies were compared with 17 from normal pregnancies.

MAIN OUTCOME MEASURES

Peripheral venous blood levels of VCAM-1 and fibronectin, measured by enzyme-linked immunoassay and radial immune diffusion technique.

RESULTS

In pre-eclampsia/eclampsia, blood VCAM-1 and fibronectin levels were higher than in normal pregnancy. Levels of both fibronectin and VCAM-1 correlated significantly with the diastolic blood pressure (r = 0.49 and r = 0.65, P < 0.001). There was also a significant direct linear correlation between plasma fibronectin and VCAM-1 levels (r = 0.57, P < 0.001). Normotensive women all had normal placental bed biopsy findings and the incidence of pathological placental bed biopsy findings increased with the severity of the pre-eclampsia.

CONCLUSION

Inadequate trophoblastic invasion of spiral arteries, and elevated levels VCAM-1 and fibronectin were found in women with pre-eclampsia. The magnitude of defective trophoblastic invasion, and blood levels of VCAM-1 and fibronectin correlate with the clinical severity of pre-eclampsia.

Normal expression of cell adhesion molecules in placentae from women with systemic lupus erythematosus and the antiphospholipid syndrome

Pregnant women with active systemic lupus erythematosus (SLE) and/or the antiphospholipid syndrome (APS) are prone to recurrent miscarriage, pre-eclampsia, intrauterine growth restriction and premature delivery. Placental dysfunction may account for these complications yet the mechanisms remain uncertain. Amongst these, an inflammatory response in the placental vasculature could play a role, involving recruitment of neutrophils and platelets and the increased endothelial expression of cell adhesion molecules (CAM), central to the recruitment process. The aim of this study was primarily to investigate CAM expression in the fetoplacental vasculature in women with SLE/APS. Circulating maternal concentrations of soluble CAM were also elucidated. There were no differences in CAM immunostaining in placentae from patients with SLE and/or APS compared with controls. In both patients and controls moderate immunostaining for the intercellular adhesion molecule-1 (ICAM-1) was observed in placental vascular endothelium and mild immunostaining was present in the placental villous stroma. Strong immunostaining for platelet endothelial CAM (PECAM) occured in the placental vascular endothelium whereas P-selectin was mildly expressed in the stem vessel endothelium only. Vascular CAM-1 (VCAM-1) and E-selectin were undetectable in either study or control placentae. In contrast, ICAM-1 and VCAM-1 but not E-selectin, as assessed by immunoassay (ELISA), were elevated in maternal serum from SLE/APS patients compared with controls. This study suggests that upregulation of CAM expression and subsequent activation of neutrophil and/or platelet activity within the placental villous tree is unlikely to be a mechanism by which the adverse pregnancy outcome arises in SLE/APS pregnancies. However, maternal endothelial cell activation (ECA) may play a more important role.

Pre-eclampsia does not change the adhesion molecule status in the placental bed

During normal placentation trophoblast cells invade maternal tissues and remodel the uterine arteries into low-resistance channels. In pre-eclampsia, trophoblast invasion is impaired and this, along with endothelial dysfunction, has been suggested to play a role in the pathogenesis of pre-eclampsia. We studied the expression of adhesion molecules important for leukocyte extravasation in the placental bed with immunohistochemistry and compared the expression in pre-eclampsia to that in normal pregnancy. Our major finding was that only invasive trophoblasts expressed cutaneous lymphocyte antigen-1 (CLA-1) in the third trimester of pregnancy, whereas villous trophoblasts did not. In the first trimester both villous trophoblasts and invasive trophoblast cells in decidua remained negative for CLA-1. Pre-eclampsia did not change the expression of leukocyte-endothelium adhesion or lymphocyte homing-associated antigens, ICAM-1, ICAM-2, VCAM, P-selectin, E-selectin, L-selectin, CLA-1, CD73, VAP-1 and alphaEbeta7 in the placental bed. Furthermore, pre-eclampsia was not associated with an aberrant accumulation of lymphocytes carrying antigens of any particular known organ-specific homing systems. The results on the unchanged pattern of adhesion molecule expression in pre-eclampsia suggests that there is no major change in the adhesive properties of the endothelium of the placental bed in pre-eclampsia.

Maternal and fetal serum nitric oxide (NO) concentrations in normal pregnancy, pre-eclampsia and eclampsia

OBJECTIVES

To measure the maternal and fetal serum concentrations of total nitrites and nitrates (as an index of nitric oxide production) in normal pregnancy, pre-eclampsia and eclampsia.

DESIGN

Three groups of women were studied cross-sectionally: late pregnant women with pre-eclampsia and eclampsia (n=31); normal late pregnant women (n=32); and age-matched healthy non-pregnant women (n=21). Venous blood samples were collected from all women and both maternal and umbilical venous samples were collected from pregnant women.

METHODS

Blood samples were assayed for nitric oxide (NO) production by Greiss reaction which measures the combined oxidation products of NO (total nitrites and nitrates).

RESULTS

There was a significant increase in serum total nitrites and nitrates concentrations in normal pregnant women than in the serum of age-matched normal non-pregnant women (P<0.0001). Significantly higher total nitrites and nitrates levels were found in the maternal sera of the pre-eclamptic and eclamptic women compared with those of normal pregnant women (P<0.0001). Also, fetal blood levels of total nitrites and nitrates were significantly increased in pre-eclampsia and eclampsia compared with those of normal pregnancy (P<0.0001).

CONCLUSIONS

(1) Serum nitric oxide (NO) production is increased in normal pregnancy than in the normal non-pregnancy. (2) Maternal and fetal serum NO levels are increased significantly in pre-eclampsia and eclampsia, which possibly represents a compensatory/protective mechanism to maintain blood flow and limit platelets aggregation in the fetal-maternal circulations. (3) The increase in NO production is directly related to the severity of pre-eclampsia; this would be of diagnostic significance for the prediction of the severity of this syndrome.

Altered circulating levels of adhesion molecules at 18 weeks' gestation among women with eventual preeclampsia: indicators of disturbed placentation in absence of evidence of endothelial dysfunction?

OBJECTIVE

The purpose of this study was to investigate whether indications of activation of the maternal endothelium were present at 18 weeks' gestation in women in whom preeclampsia eventually developed.

STUDY DESIGN

A total of 2190 blood samples were obtained at 18 weeks' gestation. Circulating levels of von Willebrand factor and soluble vascular adhesion molecule 1, soluble intercellular adhesion molecule 1, and E-selectin were assayed in 71 women with eventual preeclampsia and 71 control subjects.

RESULTS

E-selectin and von Willebrand factor levels were similar between the 2 groups. Soluble vascular adhesion molecule 1 concentration was significantly lower in the women with eventual preeclampsia (median, 649.0 ng/mL vs 762.4 ng/mL; P <.001), whereas soluble intercellular adhesion molecule 1 concentration was significantly higher (median, 239.8 ng/mL vs 178.3 ng/mL; P <.001).

CONCLUSION

We found no indications of endothelial activation at 18 weeks' gestation in women in whom preeclampsia later developed. However, decreased serum concentration of soluble vascular adhesion molecule 1 and increased serum concentration of soluble intercellular adhesion molecule 1 may reflect the disturbed placentation known to be associated with the development of preeclampsia.

Distribution of apolipoprotein(a) isoforms in normotensive and severe preeclamptic women

OBJECTIVE

Preeclampsia is a pregnancy-related disorder constituting one of the primary causes of worldwide maternal and fetal mortality, but despite intensive research its pathogenesis remains unclear. Lipids have been implicated in the development of preeclampsia, although this possible association remains controversial and not yet fully investigated. This study set out to examine the potential association between lipoprotein(a) and the development of severe preeclampsia. The focus of this study was to investigate the potential utility of apolipoprotein(a) isoforms as possible diagnostic markers for identifying women at risk for developing preeclampsia.

METHODS

Study participants included a control group of nonpregnant female volunteers (n = 59), a group of healthy pregnant (normotensive) female volunteers (n = 51), and a group of severe preeclamptic female volunteers (n = 59). Serum lipoprotein(a) concentrations were measured using double-antibody ELISA methods and were found to be 17.0+/-23.6 mg/dl among nonpregnant controls (n = 51), 15.9+/-15.8 mg/dl among healthy pregnant normotensives (n = 51), and 16.2+/-16.7 mg/dl in the preeclamptic group (n = 59). In addition, apolipoprotein (a) isoforms were identified using high-resolution SDS-agarose electrophoresis followed by immunoblotting.

RESULTS

We detected no significant differences between the groups studied in the distribution of isoforms (Chi-square = 1.21, df = 4, P = 0.89); however, in a 1-week interval we detected a 42.2% rise in Lp(a) levels as well as a 67.1% rise in C-reactive protein concentrations among 10 volunteers in the preeclamptic group (median = 9.6; P < 0.05).

CONCLUSIONS

Although the exact mechanism of pathogenesis continues to elude investigators, our results suggest that lipoprotein(a) may act as an acute-phase reactant during preeclampsia. Although our results are preliminary, they are consistent with growing evidence implicating lipids as among those factors involved in the etiology of preeclampsia. Changes in apolipoprotein(a) may be among those important biochemical markers that are found to be useful in the early identification of high-risk women and warrant further study.

Selective deficit of angiogenic growth factors characterises pregnancies complicated by pre-eclampsia

OBJECTIVE

To compare serum levels of angiogenic growth factors vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and angiogenin in pre-eclamptic women and matched controls.

DESIGN

Retrospective analysis of -70 degrees C stored serum of women who developed pre-eclampsia and matched controls.

SETTING

Department of Gynaecology and Obstetrics, St Elisabeth Hospital, Curaçao, Netherlands Antilles.

SAMPLE

Thirty women with pre-eclampsia and 30 normotensive controls matched for age and gestation.

RESULTS

VEGF and PIGF serum levels were significantly lower in pre-eclamptic pregnancies, compared with controls (VEGF 0.31 +/- 1.20 vs 18.30 +/- 24.97 pg/mL, P = 0.0004; PlGF 54.19 +/- 32.05 vs 497.95 +/- 340.51 pg/mL, P < 0.0001). Matched couple analysis showed VEGF serum concentrations to be lower in the majority of pre-eclamptic women and PlGF concentrations to be lower in all pre-eclamptic women. Angiogenin serum levels showed no statistical significant difference between pre-eclamptic pregnancies and controls (523.68 +/- 367.55 vs 670.41 +/- 251.54 ng/mL, P = 0.058), with matched couple analysis showing no clear pattern.

CONCLUSIONS

Decreased serum levels of VEGF and PIGF characterise, and therefore seem to be of importance during (the development of), pre-eclampsia. This selective deficit of angiogenic growth factors might in part explain the shallow placentation found in this pregnancy complication.

Interaction of the protein C/protein S anticoagulant system, the endothelium and pregnancy

Normal pregnancy is associated with significant changes in haemostasis, lipid metabolism and endothelial function. This suggests that maternal adaptation in these systems is required for successful pregnancy outcome. A number of acquired and heritable prothrombotic abnormalities are associated with complications in pregnancy. A common feature of these abnormalities is their ability to alter endothelial function or the protein C/protein S system and increase thrombin generation. In this review the normal function of the endothelium and the protein C/protein S system is detailed. The changes which characterize normal and complicated pregnancies are outlined and the evidence for the impact of heritable and acquired disorders of the protein C/protein S system on pre-eclampsia and fetal loss are discussed.

Elevated soluble adhesion molecules in women with pre-eclampsia. Do cytokines like tumour necrosis factor-alpha and interleukin-1beta cause endothelial activation

OBJECTIVE

The purpose of the present study was to evaluate the clinical significance of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) for endothelial cell activation in pre-eclampsia. Therefore, we determined and compared the correlations between these cytokines and circulating adhesion molecules in the sera of pre-eclamptic pregnant women, normotensive pregnant women and nonpregnant women.

METHODS

The soluble adhesion molecules VCAM-1, ICAM-1, E-selectin, and P-selectin were determined in the serum of 38 pre-eclamptic pregnant women and 40 normotensive pregnant and nonpregnant controls using ELISA-techniques. We correlated these serum concentrations with the serum levels of TNF-alpha and IL-1beta, respectively, also determined by ELISA.

RESULTS

Elevated serum levels of VCAM-1 and E-selectin could be detected in pre-eclamptic patients, with and without HELLP-syndrome. In contrast, no increased serum concentration of ICAM-1, P-selectin, TNF-alpha and IL-1beta were found in these patients. While significant correlation between VCAM-1 and E-selectin could be determined (r=0.604; p<0.001) no unambiguous correlations, however, were found between TNF-alpha or between IL-1beta and the examined adhesion molecules or the selectins.

CONCLUSIONS

In contrast to in vitro investigations on cultured umbilical vein endothelium, our experimental results indicate that the cytokines TNF-alpha and IL-1beta can not explain endothelial cell activation, and that their measurement in serum is not useful for the detection of pre-eclampsia.

A selective increase in plasma soluble vascular cell adhesion molecule-1 levels in preeclampsia

PROBLEM

The study was conducted to determine whether altered plasma levels of soluble intercellular adhesion molecule (ICAM)-1 and soluble vascular cell adhesion molecule (VCAM)-1 are involved in the pathogenesis of preeclampsia.

METHOD OF STUDY

Maternal plasma samples were collected from 20 patients with preeclampsia, 20 matched normotensive patients with uncomplicated pregnancies. and ten healthy nonpregnant women. Samples were assayed for soluble VCAM-1 and soluble ICAM-1 by specific enzyme-linked immunosorbent assay.

RESULTS

Both soluble VCAM-1 and soluble ICAM-1 were detectable in the plasma of all preeclamptic, normotensive pregnant, and nonpregnant women. The mean plasma level of soluble VCAM-1 was significantly higher in preeclamptic women compared to normotensive pregnant women (1831 ng/mL +/- 534 ng/mL vs. 1254 ng/mL +/- 386 ng/mL, respectively; P < 0.05). However, the plasma level of soluble VCAM-1 was unchanged during the third-trimester of normal pregnancy compared to nonpregnant women. The mean plasma level of soluble ICAM-1 in preeclamptic and normotensive pregnant women were increased when compared to nonpregnant women. However, the mean plasma level of soluble ICAM-1 was comparable in women with preeclampsia and normotensive pregnancy.

CONCLUSIONS

The selective increased plasma levels of soluble VCAM-1 in patients with preeclampsia provide evidence for endothelial activation and suggest distinct pathways for neutrophil and endothelial activation in preeclampsia.

The role of soluble adhesion molecules in evaluating endothelial cell activation in preeclampsia

OBJECTIVE

Adhesion molecules, such as vascular cell adhesion molecule 1, are known to be increased in the serum of patients with preeclampsia, indicating that these molecules are possible markers of endothelial cell activation. We investigated the influence of serum from women with preeclampsia on the expression of adhesion molecules by cultured endothelial cells.

STUDY DESIGN

Human umbilical vein endothelial cells were cultured in Ham/Iscove modified Dulbecco's medium containing 20% pooled human serum, l -glutamine (200 mmol/L), penicillin, and streptomycin. We stimulated these cells for 24 hours with sera from patients with preeclampsia and then determined the levels of vascular cell adhesion molecule 1, intercellular cell adhesion molecule 1, E-selectin, and P-selectin in the supernatant and in the maternal serum by means of enzyme-linked immunosorbent assay. These results were compared with those of sera obtained from normotensive pregnant and nonpregnant women. In addition, the expressions of these adhesion molecules on the endothelial surface were determined by immunofluo-rescence microscopy.

RESULTS

Only for vascular cell adhesion molecule 1 and E-selectin were elevated plasma levels found in hypertensive patients, whereas intercellular cell adhesion molecule 1 and P-selectin showed similar plasma levels in all the patients. No differences in the levels of the adhesion molecules were found between the supernatants of endothelial cell cultures after stimulation with sera from patients with preeclampsia and those after stimulation with normotensive control sera. In contrast, with immunofluorescence microscopy we could detect higher amounts of vascular cell adhesion molecule 1, intercellular cell adhesion molecule 1, and E-selectin on the endothelial surface after stimulation with sera from women with preeclampsia.

CONCLUSION

Although vascular cell adhesion molecule 1 and E-selectin were elevated in maternal serum samples from women with preeclampsia and on the endothelial surface after stimulation with such sera, there were no detectable increases in the levels of both of these adhesion molecules in the supernatant of cultured endothelial cells. We therefore assume that sera from women with preeclampsia may cause endothelial cell activation. Because we could not detect elevated concentrations of any of the investigated adhesion molecules in the supernatant of endothelial cells, we believe that factors other than sera from women with preeclampsia seem to play a major role in the release of soluble forms of adhesion molecules from the endothelial membrane.

Vascular cell adhesion molecule-1 (VCAM-1) and leukocyte activation in pre-eclampsia and eclampsia

OBJECTIVE

To evaluate the levels of VCAM-1 in pre-eclampsia/eclampsia as a possible marker of leukocyte activation and endothelial damage.

METHODS

We performed a case-control study on 25 healthy pregnant women and 35 patients diagnosed as pre-eclampsia or eclampsia which were randomly selected. Peripheral venous blood samples were obtained and serum levels of VCAM-1 were measured by enzyme-linked immunoassay (ELISA).

RESULTS

In pre-eclampsia/eclampsia, VCAM-1 levels were higher than in normal pregnancy. Serum concentrations of VCAM-1 were significantly higher in severe pre-eclampsia and eclampsia compared to mild pre-eclampsia or healthy controls. ROC analysis detected that VCAM-1 > or = 450 ng/ml had a sensitivity of 0.79 and a specificity of 0.90 in detecting severe pre-eclampsia and eclampsia.

CONCLUSION

This is the first study to correlate VCAM-1 levels with severity of disease in pre-eclampsia. Our findings indicate that increasing levels of soluble VCAM-1 are present in the circulation of patients with severe pre-eclampsia/eclampsia compared to mild pre-eclampsia or healthy pregnant women. Elevated VCAM-1 levels may represent a possible mechanism by which endothelial cells attract leukocytes and cause endothelial cell damage.

The role of the endogenous anti-inflammatory compound gravidin in pre-eclampsia

OBJECTIVES

The study's aims were to investigate the levels of gravidin, an endogenous phospholipase A2 inhibitor, in pregnancy and pre-eclampsia and to establish its effects on neutrophil function.

STUDY DESIGN

Serum samples were collected from 9 nonpregnant, 15 preeclamptic, and 10 healthy pregnant women and assayed for free gravidin by enzyme-linked immunosorbent assay. Neutrophil phospholipase A2 and respiratory burst activities were determined in the presence of isolated free gravidin by cellular arachidonic acid release and superoxide anion production.

RESULTS

Levels of free gravidin were higher in the healthy pregnant (36.1 +/- 5.5 ng/mL) and preeclamptic (17.8 +/- 2.8 ng/mL) groups than in the nonpregnant control group (3.9 +/- 0.5 ng/mL) and were significantly different between pregnancy groups (P <.01, Mann-Whitney U test). Free gravidin caused a concentration dependent decrease in N-formyl-methionyl-leucyl-phenylalanine-stimulated neutrophil arachidonic acid release (inhibitory concentration of 50% 25 nmol/L) and superoxide anion generation (inhibitory concentration of 50% 32 nmol/L).

CONCLUSIONS

Circulating levels of free gravidin are reduced in pre-eclampsia compared with normal pregnancy. This may encourage an increase in the respiratory burst of neutrophils in pre-eclampsia and could contribute to the oxidative stress and vascular damage that characterize this disease.

Etiology and pathogenesis of preeclampsia: current concepts

The etiology of preeclampsia is unknown. At present, 4 hypotheses are the subject of extensive investigation, as follows: (1) Placental ischemia-Increased trophoblast deportation, as a consequence of ischemia, may inflict endothelial cell dysfunction. (2) Very low-density lipoprotein versus toxicity-preventing activity-In compensation for increased energy demand during pregnancy, nonesterified fatty acids are mobilized. In women with low albumin concentrations, transporting extra nonesterified fatty acids from adipose tissues to the liver is likely to reduce albumin's antitoxic activity to a point at which very-low density lipoprotein toxicity is expressed. (3) Immune maladaptation-Interaction between decidual leukocytes and invading cytotrophoblast cells is essential for normal trophoblast invasion and development. Immune maladaptation may cause shallow invasion of spiral arteries by endovascular cytotrophoblast cells and endothelial cell dysfunction mediated by an increased decidual release of cytokines, proteolytic enzymes, and free radical species. (4) Genetic imprinting-Development of preeclampsia-eclampsia may be based on a single recessive gene or a dominant gene with incomplete penetrance. Penetrance may be dependent on fetal genotype. The possibility of genetic imprinting should be considered in future genetic investigations of preeclampsia.

Small low-density lipoproteins and vascular cell adhesion molecule-1 are increased in association with hyperlipidemia in preeclampsia

The pregnancy disorder preeclampsia is characterized by endothelial cell dysfunction that may be promoted by abnormal increases in circulating lipids, particularly triglycerides and free fatty acids. Serum triglyceride concentration is a major regulatory determinant of low-density lipoprotein (LDL) size and density distribution. Smaller, denser LDL particles have several intrinsic properties capable of inducing endothelial dysfunction. The present nested, case-control study of gestationally matched preeclamptic and normal pregnant women tested the hypothesis that hypertriglyceridemia in preeclampsia is accompanied by decreases in LDL peak particle diameter (predominant LDL size). Plasma LDL peak particle diameter was determined by nondenaturing 2% to 16% polyacrylamide gel electrophoresis. Correlations of LDL diameter with the concentration of serum triglycerides, free fatty acids, total cholesterol, LDL-cholesterol, and apolipoprotein B (apo B) were determined. In the same individuals, we measured serum concentrations of a marker of vascular dysfunction previously reported to be increased in preeclampsia, soluble vascular cell adhesion molecule-1 (VCAM-1), and examined the association of VCAM-1 with LDL diameter and serum lipids. LDL peak particle diameter was decreased in preeclampsia relative to normal pregnancy (P < .01). The LDL-cholesterol:apo B ratio, which frequently decreases with decreasing LDL diameter, was also decreased (P < .04). Triglyceride concentrations were increased in preeclampsia (P < .0002), and there was a significant inverse relationship between LDL peak particle diameter and triglycerides (r = -.55, P < .02). Serum soluble VCAM-1 concentrations were markedly increased in preeclampsia (P < .0003). Apo B (P < .004), free fatty acids (P < .01), total cholesterol (P < .01), and LDL-cholesterol (P < .02) were also increased. VCAM-1 correlated with apo B (r = .50, P < .03) and LDL-cholesterol (r = .50, P < .03), but showed no relationship with the LDL diameter, LDL-cholesterol:apo B ratio, or other lipids. We conclude that the predominance of smaller, denser LDL, a potential contributor to endothelial cell dysfunction, is a feature of preeclampsia. However, the serum VCAM-1 level, one indicator of endothelial involvement, may be influenced more by quantitative lipoprotein changes (serum apo B or LDL-cholesterol) than by LDL particle size.

Trophoblast pseudo-vasculogenesis: faking it with endothelial adhesion receptors

During early development, a subset of fetal (placental) cytotrophoblasts exhibits tumor-like behavior and invades the uterus. To access a supply of maternal blood, they invade arterioles and form heterotypic interactions with, and replace, resident maternal endothelium, creating a hybrid uterine vasculature. Recently, it has become clear that invading cytotrophoblasts transform their adhesion receptor phenotype to resemble the endothelial cells they replace. Furthermore, they express vasculogenic factors and receptors. Is this a form of vasculogenesis?

Serum from preeclamptic women induces vascular cell adhesion molecule-1 expression on human endothelial cells in vitro: a possible role of increased circulating levels of free fatty acids

OBJECTIVE

The object was to determine whether serum from preeclamptic women induces expression of vascular cell adhesion molecule-1 on cultured endothelial cells.

STUDY DESIGN

Endothelial cells were incubated with medium containing 20% serum (volume/volume) either from women with preeclampsia (n = 15) or from women with normal pregnancies (n = 15) matched for maternal age, gestational age, and parity. A further matched set of samples (n = 10) was exposed to endothelial cells that had previously been incubated in the presence or absence of vitamin E (40 micromol/L final concentration). Free fatty acids were determined in each sample. A mixture of free fatty acids (linoleic, oleic, and palmitic acids, 1:1:1) was added to serum from control subjects in increasing concentrations (70-280 micromol/L final concentration) to emulate preeclamptic serum and the preparation was exposed to endothelial cells. In each experiment vascular cell adhesion molecule-1 expression was determined after 16 hours of exposure by an enzyme-linked immunosorbent assay technique performed on the cell monolayer.

RESULTS

Preeclamptic serum had higher levels of free fatty acids than did that of control subjects (0.71 mmol/L, 95% confidence level 0.5-0.93, vs 0.36 mmol/L, 95% confidence level 0.28-0.43). There was a statistically significant increase in vascular cell adhesion molecule-1 expression on the endothelial cells exposed to preeclamptic serum compared with those exposed to control serum (optical density 0.17 vs 0.11). Vitamin E reduced the vascular cell adhesion molecule-1 expression of endothelial cells exposed both to preeclamptic and to control serum samples in a nonspecific manner. Addition of free fatty acids to normal pregnancy serum to mimic the effect of preeclampsia resulted in increased expression of vascular cell adhesion molecule-1 on the cells.

CONCLUSION

Preeclamptic serum induces vascular cell adhesion molecule-1 expression on human endothelial cells in vitro, an effect also produced by fatty acids. The elevated level of free fatty acids in women with preeclampsia may contribute to increased vascular cell adhesion molecule expression in vivo.

Circulating vascular cell adhesion molecule-1 in pre-eclampsia, gestational hypertension, and normal pregnancy: evidence of selective dysregulation of vascular cell adhesion molecule-1 homeostasis in pre-eclampsia

OBJECTIVE

Our purpose was to investigate circulating levels of vascular cell adhesion molecule-1 in the peripheral and uteroplacental circulations during normotensive and hypertensive pregnancies.

STUDY DESIGN

This prospective observational study involved 2 patient groups. Group 1 consisted of 22 women with pre-eclampsia and 30 normotensive women followed up longitudinally through pregnancy and post partum. There were an additional 13 women with established gestational hypertension. Group 2 consisted of 20 women with established pre-eclampsia and 19 normotensive control subjects undergoing cesarean delivery. Plasma levels of vascular cell adhesion molecule-1 were measured in blood drawn from the antecubital vein (group 1) and from both the antecubital and uterine veins (group 2). Data were analyzed by analysis of variance.

RESULTS

In group 1 vascular cell adhesion molecule-1 levels did not change significantly throughout normal pregnancy and post partum. Women with established pre-eclampsia had increased vascular cell adhesion molecule-1 levels compared with the normotensive pregnancy group (P = .01). Vascular cell adhesion molecule-1 levels were not elevated in women with established gestational hypertension. In group 2 significantly higher levels of vascular cell adhesion molecule-1 were detected in the uteroplacental (P < .0001) and peripheral (P < .0001) circulations of pre-eclamptic women by comparison with normotensive women. In the pre-eclamptic group there was a tendency toward higher vascular cell adhesion molecule-1 levels in the peripheral circulation than in the uteroplacental circulation (P = .06). In contrast to vascular cell adhesion molecule-1, circulating levels of E-selectin and intercellular adhesion molecule-1, other major leukocyte adhesion molecules expressed by the endothelium, were not different in pre-eclamptic and normotensive pregnancies.

CONCLUSION

Established pre-eclampsia is characterized by selective dysregulation of vascular cell adhesion molecule-1 homeostasis. This event is not an early preclinical feature of pre-eclampsia, does not persist post partum, is not a feature of nonproteinuric gestational hypertension, and is not observed with other major leukocyte adhesion molecules. Induction of vascular cell adhesion molecule-1 expression in pre-eclampsia may contribute to leukocyte-mediated tissue injury in this condition or may reflect perturbation of other, previously unrecognized, functions of this molecule in pregnancy.

Fetal plasma levels of circulating endothelial cell adhesion molecules in normal and preeclamptic pregnancies

OBJECTIVE

Circulating levels of endothelial cell adhesion molecules are elevated in women with preeclampsia. The aim of the present study was to determine levels of these molecules in the fetal circulation of normal pregnancies and pregnancies complicated by preeclampsia.

STUDY DESIGN

Fetal plasma samples from the umbilical vein and peripheral maternal plasma and serum sample were collected at delivery from women with preeclampsia and women with normal pregnancy. Women with non-proteinuric pregnancy-induced hypertension (PIH) were excluded from the study. A sandwich ELISA technique was employed to quantitate concentrations of soluble ICAM-1 (CD54), VCAM-1 (CD106), and E-selectin (CD62E).

RESULTS

The normal values of soluble endothelial cell adhesion molecules in the fetal circulation were determined as 162+/-45 ng/ml for ICAM-1, 1612+/-582 ng/ml for VCAM-1, and 154+/-58 ng/ml for E-selectin. They were found to markedly differ from the corresponding normal values in the maternal circulation (sICAM-1: 247+/-65 ng/ml; sVCAM-1: 715+/-170 ng/ml; sE-selectin: 34+/-14 ng/ml). The concentrations of sICAM-1, sVCAM-1, and sE-selectin were significantly elevated in women with preeclampsia compared to healthy control pregnant women. In contrast, there was no difference in the circulating fetal concentrations of these molecules between normal pregnancies and pregnancies complicated by preeclampsia.

CONCLUSIONS

Normal values of sICAM-1, sVCAM-1, and sE-selectin in fetal circulation are markedly different from the values obtained for healthy adults. Plasma concentrations of these molecules are elevated in women with preeclampsia but not in the fetal circulation of preeclamptic pregnancies suggesting that based on the analysis of soluble adhesion molecules the fetal circulation may not be affected by the factor(s) that lead to disturbed endothelial cell function in women with preeclampsia.

Pre-eclampsia--still a disease of theories?

The pathophysiology of pre-eclampsia remains poorly understood. Moreover, there is no reliable predictive test and no effective prophylactic therapy for this disease. Advances have, however, recently been made in our understanding of the genetics of pre-eclampsia and in the processes which lead to abnormal trophoblastic invasion in pre-eclampsia. Prediction and prevention are intimately linked, and both problems will only be solved by further unravelling of the complex pathophysiology of pre-eclampsia.

Soluble intercellular adhesion molecule-1 serum profile in physiologic and preeclamptic pregnancy

PROBLEM

The aim of this study was to determine serum levels of soluble intercellular adhesion molecule (sICAM)-1, an adhesion receptor that mediates interactions with the immune system, in physiologic and preeclamptic pregnancies. Moreover, we evaluated whether the release of sICAM-1 during pregnancy correlated to plasma fibronectin concentrations.

METHOD OF STUDY

Serum was collected from 18 nonpregnant, control women, from 58 normal pregnant women during the first (n = 13), second (n = 15), and third (n = 30) trimesters, and from 25 preeclamptic patients at 27-39 weeks' gestation. All samples were assayed for sICAM-1 by a specific enzyme-linked immunoassay and for fibronectin by a nephelometric system. Serum sICAM-1 levels in preeclamptic patients were compared to those obtained from gestational-matched normal pregnant women.

RESULTS

Levels of sICAM-1 were significantly elevated (P < 0.001) in each of the three trimesters of normal pregnancy (I trimester: 390.4 +/- 25.7 ng/ml; II trimester: 386.3 +/- 15.4 ng/ml; and III trimester: 367.3 +/- 15.8 ng/ml) when compared to those of healthy nonpregnant women (263.3 +/- 11.6 ng/ml). No significant difference in sICAM-1 concentrations was observed among the three trimesters. Preeclampsia was associated to a significant decrease (P < 0.01) of sICAM-1 levels (309.8 +/- 11.6 ng/ml) relative to those observed in gestational-matched pregnant women (367.3 +/- 15.8 ng/ml). Fibronectin and sICAM-1 levels did not correlate.

CONCLUSION

The increased levels of sICAM-1 found in physiologic pregnancies and its reduction in preeclampsia may account for some of the immunologic alterations demonstrated to be associated with pregnancy.

Plasma concentrations of asymmetric dimethylarginine, a natural inhibitor of nitric oxide synthase, in normal pregnancy and preeclampsia

OBJECTIVE

We investigated the change in the plasma concentration of asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide synthase, in early-, mid-, and late-gestation normotensive pregnancies and in gestational age-matched preeclamptic pregnancies and compared the observed changes with changes in blood pressure.

STUDY DESIGN

Blood pressure and peripheral plasma asymmetric dimethylarginine concentrations were measured in 20 nonpregnant and 145 pregnant women (33 first-trimester, 50 second-trimester, and 44 third-trimester normotensive pregnancies and 18 third-trimester pregnancies complicated by preeclampsia). In 23 normotensive pregnancies serial plasma asymmetric dimethylarginine concentrations were measured. Statistical analysis was by analysis of variance and linear regression.

RESULTS

The blood pressures recorded throughout normal pregnancy were significantly lower than in nonpregnant subjects (p < 0.0001). The mean systolic, diastolic, and average blood pressures were significantly higher in the second-trimester groups than in the first-trimester groups, whereas in the third trimester average and diastolic blood pressures were significantly higher than in the second trimester. The mean (+/-SD) systolic and diastolic blood pressures in third-trimester preeclamptic patients was 157.7 +/- 11.2 and 110.9 +/- 8.5 mm Hg. The mean plasma asymmetric dimethylarginine concentration in nonpregnant women was 0.82 +/- 0.31 micromol/L (significantly higher than in normotensive pregnancy, p < 0.0001). The plasma asymmetric dimethylarginine concentration was also significantly higher in second-trimester than in first-trimester normotensive groups (respectively, 0.52 +/- 0.20 micromol/L and 0.40 +/- 0.15 micromol/L, p = 0.001) and was higher in third-trimester normotensive pregnancy 0.56 +/- 0.23 micromol/L than it was in the second trimester. The asymmetric dimethylarginine concentration in third-trimester preeclamptic patients was 1.17 +/- 0.42 micromol/L (p < 0.0001 vs normotensive third-trimester subjects).

CONCLUSIONS

It is well recognized that blood pressure falls in early normal pregnancy and rises again toward term. These studies show that the early fall in blood pressure is accompanied by a significant fall in the plasma asymmetric dimethylarginine concentration. Later in pregnancy circulating concentrations increase and, when pregnancy is complicated by preeclampsia, concentrations are higher than in the nonpregnant state. Our data support a role for both asymmetric dimethylarginine and nitric oxide in the changes in blood pressure seen in both normal and preeclamptic pregnancy.

Preeclamptic nephropathy -- an endothelial lesion. A morphological study with a review of the literature

OBJECTIVE

We investigated wether an endothelial lesion, postulated in pathogenesis of preeclampsia (PE) in general, is also pathogenetically relevant in the characteristic renal lesions of PE, presenting as special glomerular alterations, designated as "preeclamptic nephropathy".

STUDY DESIGN

Renal biopsies of 90 women with PE were analyzed by light microscopy (LM), immunohistology (IH) and electron microscopy (EM). Corresponding with clinical data clinicomorphological correlations were performed.

RESULTS

In IH and EM the altered glomeruli demonstrate an endothelial lesion. Consecutive morphological reactions could be revealed by EM, allowing a subdivision in different stages of disease. The late stage indicates the reversibility of these renal lesions. Close correlations were found between clinical and morphological data. Focal glomerulosclerosis presents a hyperperfusion lesion, developing only facultatively in PE as a result of hyperfiltration.

CONCLUSION

In preeclamptic nephropathy the first morphological substrate of renal changes with the key to pathogenesis presents itself as an endothelial lesion. This results in a disturbance of glomerular basement membrane permeability and in an imbalance of different mediator systems, with dominance of vasoconstrictive reactions but also coagulative-, reparation-, and proliferation-processes, leading to the characteristic glomerular alterations of preeclamptic nephropathy.

New concepts in coagulation

The process of blood coagulation is a complex and incompletely understood process. In the last decade or so critical steps have been taken toward better understanding this process. It is now widely agreed that the principal initiating pathway of coagulation is the so-called extrinsic pathway due to the action of tissue factor and Factor VII. Concomitant with this appreciation has come an understanding and elucidation of the roles of tissue factor pathway inhibitor. Although the "intrinsic pathway" is no longer felt to be the initiator of coagulation, recent evidence suggests that Factor XIa may constitute an important amplification pathway of the coagulation system in vivo. Refinement of flow cytometry has enabled the detection of novel platelet antigens on activated platelet surfaces. It is hoped that detection and characterization of these antigens, including adhesion molecules such as P-selectin, will enable further understanding of the platelet's role in pathological coagulation and inflammation. The endothelium is also intricately involved and recent work has determined the importance of endothelial produced factors such as endothelium-derived relaxation factor, endothelin, and thrombomodulin. Finally, with the meteoric rise in molecular genetic technology, specific genetic abnormalities in a number of plasma proteins has been elucidated, with marked implications on the understanding of the coagulation process. For example, the mutation on the gene for Factor V, leading to Arg506 replacement with Gln, produces activated protein C resistance with a concomitant increased risk of venous thrombosis. Thus, significant advances in knowledge of the endothelium, platelets, and plasma factors involved in coagulation have been made and now the challenge of the future is to better elucidate the interactions of these components.

Plasma concentrations of Lp(a) lipoprotein and TGF-beta1 are altered in preeclampsia

This study was performed to investigate the possible association between preeclampsia and the plasma concentrations of Lp(a) lipoprotein and TGF-beta1 in a large series of patients. Additionally, correlation between the concentrations of these molecules and the severity of preeclampsia or fetal growth retardation was evaluated. Following clinical examination and biochemical analyses, both electroimmunoassay and RIA technique were used for quantitative determinations of plasma Lp(a) lipoprotein. ELISA technique was used to measure the active form of TGF-beta1 in plasma of pregnant normotensive and preeclamptic women. We examined 154 women with preeclampsia (preeclampsia group) and 76 healthy, pregnant normotensive women (control group). The preeclampsia group was further divided into the following subgroups: mild preeclampsia, severe preeclampsia and preeclampsia with fetal growth retardation. Plasma levels of Lp(a) lipoprotein were lower in the total preeclampsia group as well as in all preeclampsia subgroups (5.45+/-7.41, 5.58+/-8.02, 5.08+/-5.38, and 4.32+/-5.28 mg/dl in the total preeclampsia group, and in subgroups with mild preeclampsia, severe preeclampsia, and preeclampsia with fetal growth retardation, respectively) than in the control group (7.84+/-9.26 mg/dl) as determined by quantitative electroimmunoassay. Corresponding results were obtained with a radioimmunoassay (166.03+/-200.2 U/l in the total preeclampsia group vs. 229.18+/-257.7 U/l in controls). There was good correlation between the two methods used for Lp(a) lipoprotein measurement. The differences between controls and the total preeclampsia group as well as each preeclampsia subgroup were statistically significant by a non-parametric test (one-way Kruskal-Wallis test). Plasma concentrations of the active form of TGF-beta1 were increased in all preeclampsia subgroups as well as in the total group (5.63+/-1.68 ng/ml) compared to controls (4.67+/-1.33 ng/ml). This increase in TGF-beta1 was statistically highly significant. Plasma concentrations of Lp(a) lipoprotein and the active form of TGF-beta1 did not differ significantly between the preeclampsia subgroups. The outcome of this study may suggest involvement of both parameters in the pathophysiology of preeclampsia and may substantiate the notion of a multifactorial etiology of the disease.

Circulating bioactive tumor necrosis factor-alpha, tumor necrosis factor-alpha receptors, fibronectin, and tumor necrosis factor-alpha inducible cell adhesion molecule VCAM-1 in uncomplicated pregnancy

OBJECTIVES

Our goal was to assess in a longitudinal study of uncomplicated pregnancy the course of maternal plasma concentrations of the bioactive cytokine tumor necrosis factor-alpha, the soluble tumor necrosis factor-alpha receptors sTNFRI and sTNFRII, the soluble cell adhesion molecule sVCAM-1, and circulating fibronectin.

STUDY DESIGN

Blood was collected from 22 healthy pregnant women at 7 to 17, 18 to 22, 23 to 28, and 30 to 36 weeks' gestation and post partum. Plasma samples were measured by bioassay for bioactive tumor necrosis factor-alpha, by immunoassay for sTNFRI, sTNFRII, and VCAM-1, and by radial immunodiffusion for circulating fibronectin, and data were statistically analyzed.

RESULTS

Plasma concentrations of all variables were significantly linked with gestational age. Levels of bioactive tumor necrosis factor-alpha and sTNFRII showed a parallel rise in the second trimester and a decrease thereafter. Values for sTNFRI and sTNFRII and for these receptors and VCAM-1 were correlated, a weak correlation between bioactive tumor necrosis factor-alpha and sTNFRII was observed, and no correlation between circulating fibronectin and other variables was apparent.

CONCLUSIONS

All variables studied exhibited a characteristic pattern depending on gestational age, which supports the concept of a physiologic role of tumor necrosis factor-alpha in pregnancy.

Circulating endothelial cell adhesion molecules as diagnostic markers for the early identification of pregnant women at risk for development of preeclampsia

OBJECTIVE

The aim of the current study was to determine levels of circulating endothelial cell adhesion molecules during preeclampsia and to assess their predictive value as diagnostic markers for the early identification of pregnant women at risk of developing preeclampsia.

STUDY DESIGN

Plasma samples were obtained from women with preeclampsia; the syndrome of hemolysis, elevated liver enzymes, and low platelets; uncomplicated pregnancy-induced hypertension; and women with normal pregnancy. In addition, longitudinal plasma profiles of pregnant women were randomly collected to determine individual profiles of circulating endothelial cell adhesion molecules. A sandwich enzyme-linked immunosorbent assay technique was used to quantitate concentrations of soluble intercellular adhesion molecule-1 (CD54), vascular cell adhesion molecule-1 (CD106), E-selectin (CD62E), platelet endothelial cell adhesion molecule (CD31), and P-selectin (CD62P).

RESULTS

Plasma levels of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin, and platelet endothelial cell adhesion molecule-1 were significantly elevated in women with preeclampsia compared with healthy control pregnant women. Longitudinal analysis of soluble plasma intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 levels during pregnancy revealed that these molecules (1) show little variation in healthy pregnant women, (2) do not vary during normal pregnancy, and (3) are significantly elevated in women with preeclampsia and the syndrome of hemolysis, elevated liver enzymes, and low platelets compared with control pregnant women and those with uncomplicated pregnancy-induced hypertension. Analysis of soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 levels in longitudinal profiles of pregnant women identified significantly elevated levels of these molecules in the plasma of preeclampsia-prone women 3 to 15 weeks before the onset of clinical symptoms.

CONCLUSION

Elevated soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 measurements during pregnancy can be considered as major risk factors. Elevated levels of these substances in the plasma of pregnant women with preeclampsia support the concept of a primary endothelial cell involvement in the pathogenesis of preeclampsia. Although currently based on a limited database, significantly elevated levels of soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in the plasma of otherwise healthy pregnant women suggest a very high predictive value of these molecules for the earliest identification of women at risk of developing preeclampsia.

Antioxidants in the treatment of severe pre-eclampsia: an explanatory randomised controlled trial

OBJECTIVE

To determine whether antioxidant therapy alters the disease process in severe early onset pre-eclampsia, in support of the hypothesis that increased lipid peroxides and reactive oxygen species production-play an important role in the pathogenesis of the disease.

DESIGN

Randomised, double-blind, placebo controlled trial.

SETTING

Two tertiary care, referral hospitals in Johannesburg, South Africa.

PARTICIPANTS

Women with severe pre-eclampsia diagnosed between 24 and 32 weeks of gestation.

INTERVENTION

Combined antioxidant treatment with vitamin E (800 IU/day), vitamin C (1000 mg/day), and allopurinol (200 mg/day).

MAIN OUTCOME MEASURES

PRIMARY OUTCOMES

1. prolongation of pregnancy and 2, biochemical assessment of lipid peroxides and antioxidants.

SECONDARY OUTCOMES

data on maternal complications, side effects of treatment, infant outcomes and regular assessment of haematologic and renal parameters.

RESULTS

The proportion of women delivered within 14 days in the antioxidant group was 52% (14/27) compared with 76% (22/29) in the placebo group (relative risk 0.68, 95% confidence interval 0.45-1.04). One woman in each group had eclampsia. Eleven women (42%) in the antioxidant and 16 (59%) in the placebo group required two antihypertensives for blood pressure control. Trial medications were well tolerated with few side effects. Lipid peroxide levels were not significantly altered in the antioxidant and placebo groups. Serum uric acid levels decreased and vitamin E levels increased significantly.

CONCLUSION

The results of this explanatory randomised trial do not encourage the routine use of antioxidants against pre-eclampsia. However, further research with modified strategies such as earlier initiation of therapy or different combinations seem worthwhile.

Increased levels of intercellular adhesion molecules and vascular cell adhesion molecules in pre-eclampsia

OBJECTIVE

To investigate the correlation between soluble forms of the intercellular adhesion molecule (sICAM-1) and vascular cell adhesion molecule (sVCAM-1) and the severity of pre-eclampsia or its possible consequences for fetal growth.

DESIGN

Prospective observational study.

SETTING

Institute of Medical Genetics, University of Oslo, Department of Medical Genetics and Haematological Research Laboratory, Ullevål University Hospital; and the Department of Obstetrics and Gynaecology, The National Hospital, Oslo, Norway.

PARTICIPANTS

Seventy-six women with normotensive pregnancies and 157 women with pre-eclampsia divided into three subgroups: mild, severe and pre-eclampsia with fetal growth retardation.

METHODS

ELISA-measurements of plasma sICAM-1 and sVCAM-1 were performed in a group of healthy pregnant normotensive women and three groups of women with varying degrees of pre-eclampsia.

RESULTS

sICAM-1 concentrations were higher in the pre-eclampsia group compared with the control group, but this difference was not statistically significant. Plasma concentrations of sVCAM-1 were significantly greater (P < 0.0001) in all pre-eclampsia subgroups (835.34, 855.25 and 964.05 ng/mL) compared with the control group (667.62 ng/mL). Within the pre-eclampsia group, plasma concentration of sVCAM-1 was significantly higher in the subgroup exhibiting fetal growth retardation (P = 0.03) compared with mild pre-eclampsia.

CONCLUSION

The observed increases in plasma concentrations of sVCAM-1 suggest that measurements of this adhesion molecule may be useful in monitoring pregnancies with respect to the development of pre-eclampsia or fetal growth retardation.

Placental cytokines and the pathogenesis of preeclampsia

The authors explore the hypothesis that tumor necrosis factor-alpha (TNF-alpha) and possibly other inflammatory cytokines are overproduced by the placenta in response to local ischemia/hypoxia contributing to increased plasma levels, and subsequent endothelial activation and dysfunction in the pregnancy disorder, preeclampsia. It is widely held that inadequate trophoblast invasion and physiologic remodeling of spiral arteries initiate placental ischemia/hypoxia in preeclampsia. Furthermore, focal areas of placental hypoxia have been implicated in the production of "toxic" factor(s) by the placenta, which circulate and cause maternal disease. Placental trophoblast cells and fetoplacental macrophages normally produce TNF-alpha and interleukin-1 (IL-1), which are capable of producing endothelial cell activation and dysfunction. Hypoxia has recently been reported to increase TNF-alpha and IL-1 production by term villous explants from the human placenta. Placental cells also express erythropoietin (EPO), which is the prototype molecule for transcriptional regulation by hypoxia in mammals. Interestingly, TNF-alpha and IL-1 have DNA sequence homologous or nearly homologous to the hypoxia-responsive enhancer element of the EPO gene, thus providing a potential, but as of yet, untested molecular link between placental hypoxia and stimulation of cytokine production. Inflammatory cytokines overproduced by the placenta in response to hypoxia may then lead to increased plasma levels and endothelial activation and dysfunction in preeclampsia. The purpose of this short review is to critically evaluate the hypothesis that placental cytokines contribute to the pathogenesis of preeclampsia. Of note, the etiology of the disease presumably related to deficient trophoblast invasion is beyond the scope of this work.

Suppression of serum vascular endothelial growth factor immunoreactivity in normal pregnancy and in pre-eclampsia

OBJECTIVE

To determine whether vascular endothelial growth factor (VEGF) concentrations are altered in pre-eclampsia.

DESIGN

Serum was prepared from peripheral venous blood and stored at -70 degrees C. Serum VEGF concentrations were measured by ELISA.

SETTING

University of Glasgow Department of Obstetrics and Gynaecology, Royal Infirmary, Glasgow.

PARTICIPANTS

Twenty-two healthy nonpregnant volunteer women, 34 normal pregnant women and 34 women with pre-eclampsia were studied.

RESULTS

Serum concentrations of VEGF were significantly lower in normal pregnant women (median value 12.89 pg/mL) than in nonpregnant women (median value 166 pg/mL; P < 0.0001). In pre-eclampsia VEGF concentrations were significantly lower (median value 2.34 pg/mL) than normal pregnancies (P < 0.0001). Postpartum concentrations of VEGF in the group complicated by pre-eclampsia (median value 76.42 pg/mL) were not significantly different from nonpregnant values (P = 0.2).

CONCLUSIONS

Our results show that serum concentrations of VEGF are suppressed in pregnancy and further reduced in pre-eclampsia. Further studies to elucidate the mechanisms which lead to a reduction in VEGF concentrations may provide new clues to the aetiology of this disorder.

Increased maternal plasma levels of soluble adhesion molecules (ICAM-1, VCAM-1, E-selectin) in preeclampsia

The physiological significance of soluble adhesion molecules has not been elucidated but it has been reported that a number of cytokines may increase the cleavage of soluble adhesion molecules. The fact that preeclampsia is associated with both increased cytokine concentrations and endothelial cell damage led us to analyse levels of soluble adhesion molecules in preeclamptic women and to compare these levels to the disease state. Since the cytokine network is altered by reproduction, the present study also raised the question as to whether levels of soluble adhesion molecules differ between pregnant and non-pregnant women, and whether variations occur with relation to gestational age or delivery. Levels of soluble adhesion molecules (intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin) in 25 preeclamptic women were compared to those in healthy pregnant women matched for age, parity and gestation, and the levels of soluble adhesion molecules of 40 healthy pregnant women at different gestational ages were determined and compared to those of 15 non-pregnant women. Concentrations were measured by ELISAs. Levels of ICAM-1, VCAM-1 and E-selectin concentrations were elevated in preeclamptic pregnancies, whereas serum levels in normal pregnancy did not differ from those of non-pregnant women. No changes were observed in relation to gestational age or delivery.

Endothelial adhesion molecules and leukocyte integrins in preeclamptic patients

Endothelial cell activation is important in the pathogenesis of preeclampsia; however, the nature of the activation is unknown. We investigated 22 patients with preeclampsia. 29 normotensive pregnancies, and 18 nonpregnant women to test the hypothesis that serum from preeclamptic patients induces expression of intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1) and stimulates intracellular free calcium concentrations [Ca2+]i in cultured endothelial cells. We then asked whether the corresponding integrin adhesive counter receptors lymphocyte function-associated antigen-1 (CD11a/CD18), macrophage-1 antigen (CD11b/CD18), p150,95 (CD11c/CD18), and very late activation antigen-4 (CD49/CD29) are increased in patients with preeclampsia. In the pregnant women, the measurements were conducted both before and after delivery. Integrin expression was measured by fluorescent antibody cell sorting analysis using monoclonal antibodies. ICAM-1 and VCAM-1 were analyzed on endothelial cells by enzyme-linked immunosorbent assay. [Ca2+]i was measured with fura 2. Serum from preeclamptic patients increased endothelial cell ICAM-1 expression but not VCAM-1 expression. Preeclamptic patients' serum also increased [Ca2+]i in endothelial cells compared with serum from normal nonpregnant or normal pregnant women. Endothelial cell [Ca2+]i concentrations were correlated with the ICAM-1 expression in preeclamptic patients (r = .80, P < .001) before but not after delivery. Expression of the integrin counter receptors on leukocytes was similarly increased in preclampsia and normal pregnancy compared with the nonpregnant state. The expression decreased significantly after delivery in both groups. Our results demonstrate that serum from preeclamptic women induces increased ICAM-1 surface expression on endothelial cells, while the expression of the integrin counterreceptors was not different. The effect on endothelial cells may be related to an increase in [Ca2+]i. The effect on cultured endothelial cells and the rapid decrease after delivery suggests the presence of a circulating serum factor which increases endothelial cell [Ca2+]i and enhances adhesion molecule expression.

Expression of cell adhesion molecules in placentae from pregnancies complicated by pre-eclampsia and intrauterine growth retardation

Platelets and neutrophils are involved in maternal placental vascular damage in pre-eclampsia. Recruitment of these cells is probably mediated by cell adhesion molecules expressed at the uteroplacental bed. It remains controversial as to whether platelets and neutrophils mediate damage to trophoblast or villous vasculature. The purpose of this study was to determine the expression of cell adhesion molecules in placentae from normal pregnancies and pregnancies complicated by pre-eclampsia and intrauterine growth retardation (IUGR). Immunostaining for platelet endothelial cell adhesion molecule (PECAM) and intercellular adhesion molecule-1 (ICAM-1) was localized mainly to the endothelium of stem villi, intermediate villi, terminal villi and decidual vessels. Scattered staining for ICAM-1 was also evident in the stroma and fetal membranes. The endothelium of stem villi, intermediate villi and terminal villi were all negative for vascular cell adhesion molecule-1 (VCAM-1) and E-Selectin. PECAM, ICAM-1 and ICAM-2 mRNA were all detectable in normal placentae using northern blotting analysis whereas mRNA for E-Selectin and VCAM-1 were both undetectable. There were no differences in cell adhesion molecule immunostaining or mRNA expression in placentae from pregnancies complicated by pre-eclampsia and IUGR inconclusion, expression of cell adhesion molecules in placentae from pre-eclampsia and IUGR are consistent with a normal physiological role in vascular function.