Abstract
Objective. Preeclampsia and pregnancies complicated by small-for-gestational age (SGA) neonates share several underlying mechanisms of disease. However, while an exaggerated systemic maternal inflammatory response is regarded as one of the hallmarks of the pathogenesis of preeclampsia, the presence of a similar systemic intra-vascular inflammation in mothers of SGA neonates without hypertension is controversial. The aim of this study was to determine phenotypic and metabolic changes in granulocytes and monocytes of women who develop preeclampsia and those who deliver an SGA neonate, compared to normal pregnant women.
Methods. This cross-sectional study included patients with a normal pregnancy (n = 33), preeclampsia (n = 33), and an SGA without preeclampsia (n = 33), matched for gestational age at blood sample collection. Granulocyte and monocyte phenotypes were determined by flow cytometry, using monoclonal antibodies against selective cluster of differentiation (CD) antigens. The panel of antibodies included the following: CD11b, CD14, CD16, CD18, CD49d, CD62L, CD64, CD66b, and HLA-DR. Intracellular reactive oxygen species (iROS) were assessed at the basal state and after stimulation (oxidative burst). Results were reported as mean channel brightness (MCB) or intensity of detected fluorescence. Analysis was conducted with non-parametric statistics. A p-value < 0.01 was considered statistically significant.
Results. (1) Women who delivered an SGA neonate had a higher MCB of CD11b in granulocytes and monocytes than those with a normal pregnancy (p < 0.001 for both); (2) patients with preeclampsia had a lower median MCB of CD62L in granulocytes (p = 0.006) and a higher median basal iROS and oxidative burst in monocytes than women with an SGA neonate (p = 0.003 and p = 0.002, respectively).
Conclusion. Pregnancies complicated by the delivery of an SGA neonate are characterized by a higher activation of maternal peripheral leukocytes than in normal pregnancies, but lower than in pregnancies complicated by preeclampsia.
Introduction
Preeclampsia and small-for-gestational age (SGA) fetuses represent two of the ‘great obstetrical syndromes’ [Citation1]. These two conditions are the clinical end point of different pathophysiologic mechanisms and are frequently associated with each other, so that the presence of an SGA fetus is also considered as a criterion of the severity of preeclampsia [Citation2]. The known pathological pathways shared by preeclampsia and SGA include the following: (1) abnormal placentation [Citation3–8]; (2) chronic utero-placental ischemia [Citation9–28]; (3) an imbalance between angiogenic and anti-angiogenic factors in maternal blood [Citation29–51]; (4) increased trophoblast apoptosis/necrosis [Citation52]; and (5) an enhanced maternal systemic inflammatory response [Citation53–79].
Given the several common risk factors, it is unclear why some women will develop a systemic maternal disease with or without fetal involvement and others will have an SGA fetus without maternal hypertension. Friedman et al. [Citation80] have proposed that the difference between preeclampsia and SGA rests on the fact that the excessive maternal response is systemic in the former, whereas it is limited to the utero-placental compartment in the latter. However, this hypothesis has been challenged by others who reported increased neutrophil [Citation55,Citation64] and endothelial [Citation69] activation in the peripheral blood of women with an SGA fetus. Previous flow cytometry studies have demonstrated that normal pregnancy is associated with changes in the phenotype and the metabolic activity of immune cells consistent with leukocyte activation [Citation60,Citation81], and that these changes are further accentuated in several pregnancy complications such as pyelonephritis [Citation81], preterm labor [Citation82], preterm prelabor rupture of membranes [Citation83], and preeclampsia [Citation60,Citation64,Citation66,Citation67]. Thus, it is possible that preeclampsia and SGA differ in the severity and the extent of the maternal inflammatory response, as reflected by changes in the immunophenotype and metabolic activity of the leukocytes in the innate immune system.
The aims of this study were to examine the phenotypic and metabolic changes in maternal granulocytes and monocytes between the following: (1) women with a normal pregnancy and those who delivered an SGA neonate; and (2) women with preeclampsia and those who delivered an SGA neonate without preeclampsia.
Material and methods
Study design and population
A cross-sectional study was conducted to compare the phenotypic and metabolic characteristics of peripheral blood granulocytes and monocytes obtained from 99 patients in the following groups: (1) normal pregnant women (n = 33); (2) women with preeclampsia (n = 33); and (3) women who delivered an SGA neonate without preeclampsia (n = 33). Patients were matched for gestational age at blood sampling (within 2 weeks).
Eligible patients were approached at the Detroit Medical Center/Wayne State University in Detroit, Michigan. Biological materials and some results of flow cytometric analysis of patients included in this study have been used for other studies of inflammation in pregnancy complications reported elsewhere. All women provided written informed consent prior to the collection of maternal blood. The collection and utilization of maternal blood for research purposes was approved by the Institutional Review Boards of Wayne State University and by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, DHHS.
Clinical definitions
Patients with normal pregnancies met the following criteria: (1) no medical, obstetrical, or surgical complication; (2) gestational age ranging from 20 to 41 weeks; and (3) delivery of a term neonate (≥ 37 weeks), appropriate for gestational age, without complications. Preeclampsia was defined as the onset of hypertension (systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg on at least two occasions, 4 h to 1 week apart) after 20 weeks of gestation and proteinuria (≥ 300 mg in a 24 h urine collection at least one dipstick measurement ≥ 2+) [Citation2]. An SGA neonate was defined by sonographic estimated fetal weight below the 10th percentile for gestational age and confirmed by neonatal birthweight [Citation84].
Blood samples collection
A sample of peripheral blood was obtained by venipuncture using a syringe, added to an anticoagulant solution (20 μg/ml of the protease inhibitor leupeptin), placed on ice, and transported to the laboratory. The blood was processed and analyzed within 60 min of phlebotomy.
Flow cytometry studies
Evaluation of the granulocytes and monocytes surface markers was performed following the methods described by McCarthy and Macey [Citation85,Citation86]. Upon arrival of the sample to the laboratory, a vital nucleic acid dye – LDS-751 – (Molecular Probes, Eugene, OR, USA) was immediately added to the specimen (final concentration was 0.0001%). The objective of this step was to separate leukocytes from anucleated red blood cells. Anti-sera against the cluster of differentiation (CD) markers and blood were mixed in pre-cooled tubes. This study included a panel of 12 tubes containing optimal concentrations of negative isotype control antibodies (IgG1 and IgG2a), CD11b, CD14, CD15, CD16, CD18, CD49d, CD62L, CD64, CD66b, and HLA-DR (Immunotech, Miami, FL, USA), which had been conjugated to the fluorescent dye, fluorescein isothiocyanite (FITC). After 10-min incubation with the anti-sera, samples were analyzed with a flow cytometer.
Flow cytometry analysis was performed on a Coulter XL-MCL (with an argon-ion 488-nm laser) flow cytometer. FITC was detected at 525 nm and LDS-751 at 620 nm. Red blood cells, which are not labeled with LDS-751, were excluded from the analysis. Granulocytes and monocytes were gated according to the characteristic staining pattern. For both cell types, the intensity of fluorescence or mean channel brightness (MCB) was recorded. The surface markers studied and the percentage of positive staining cells for each marker in healthy non-pregnant women are described in .
Table I. Leukocyte surface antigens analyzed and staining of leukocyte subpopulation with specific monoclonal antibodies with the use of whole-blood flow cytometry.
The presence of intracellular reactive oxygen species (iROS) within granulocytes and monocytes was assessed by determining the basal content, the production in response to a stimulant (i.e. oxidative burst), and the stimulation index (ratio between oxidative burst and basal value of iROS). This was performed using the method described by Himmelfarb et al. [Citation87]. Briefly, 1 ml of peripheral blood, which was drawn with a syringe and inserted into a tube containing sodium heparin (10 IU/ml), was placed on ice and transported to the laboratory. The cells were incubated for 15 min at 37°C with 2′,7′ dichlorofluorescein diacetate (DCFH-DA), which diffuses across the cell membrane and is trapped within the cell by a deacetylation reaction. When the DCFH-DA is exposed to hydrogen peroxide, it is oxidized to the highly fluorescent 2′,7′ dichlorofluorescein (DCF).
The oxidative burst was studied by adding 10 μl of N-formyl-methionyl-leucyl-phenylalanine (FMLP) (Sigma, St. Louis, MO), dissolved in ethanol to a tube containing 50 μl of blood and DCFH-DA. The contents were gently mixed and incubated for 30 min at 37°C. After this period of time, 5 μl of LDS-751 (final concentration 0.0001%) in methanol was added, mixed, and incubated for 1 min at room temperature. The samples were then analyzed immediately on the flow cytometer. DCF was detected at 525 nm, LDS-751 at 620 nm, and phycoerythrin at 575 nm. FITC mean channel density staining was calibrated before analysis with Standard Brite Beads (Beckman Coulter, Miami, FL). A discriminator was set to exclude red blood cells, which do not label with LDS-751. Granulocytes were gated using an LDS-751 versus side scatter histogram, and the monocytes using a CD14-phycoerythrin versus side scatter histogram. The MCB was measured. Ten thousand events, excluding red blood cells, were collected for the analysis.
Statistical analysis
Kruskal–Wallis and post-hoc with Mann–Whitney U tests were employed for comparisons of continuous variables. Chi-square tests were utilized for comparison of proportions. The statistical package used was SPSS v.12.0 (SPSS, Chicago, IL). A p-value < 0.01 was considered significant.
Results
Patients' characteristics
The demographic and clinical characteristics of the study groups are displayed in . There were no significant differences in maternal age, ethnic group distribution, and gestational age at sample collection among the three groups. As expected, the group with preeclampsia had the highest proportion of nulliparous women.
Table II. Demographic and clinical characteristics of the study groups.
Differences in phenotypes and metabolic activity in leukocytes between women with a small-for-gestational age neonate and those with a normal pregnancy
Patients with an SGA had a significantly higher median MCB of CD11b, a marker of leukocyte adhesion to vascular endothelium [Citation88], than normal pregnant women in both granulocytes and monocytes (p < 0.001 for each; see and ). The median oxidative burst and the stimulation index for both granulocytes and monocytes were higher in patients with an SGA than in those with a normal pregnancy, but these trends did not reach the statistical significance threshold set up for this study (p = 0.03 for both comparisons in granulocytes and p = 0.02 for both comparisons in monocytes, respectively; see ). There were no significant differences in surface marker expression, baseline iROS, and oxidative burst in response to FMLP according to the severity of an SGA (less than or more than 5th percentile of birthweight for gestational age) (all p > 0.01, data not shown).
Table III. Mean channel brightness of labeled antibody binding to peripheral blood granulocytes.
Table IV. Mean channel brightness of labeled antibody binding to peripheral blood monocytes.
Table V. Mean channel brightness of intracellular DCFH-DA activated iROS at baseline and after stimulation with FMLP (oxidative burst) and stimulation index (ratio of iROS after stimulation over base line level) in peripheral blood.
Differences in phenotypes and metabolic activity in leukocytes between patients with preeclampsia and women with a small-for-gestational age neonate
Women with preeclampsia had a lower median MCB of CD62L in granulocytes than those with an SGA neonate (p = 0.006; see ). Expression of the surface antigen CD62L is known to be down-regulated during leukocyte activation.[Citation89] The median MCB for basal iROS and the response to FMLP in monocytes were significantly higher in patients with preeclampsia than that of those with an SGA neonate (p = 0.003 and p = 0.002, respectively; see ). Similarly, the median MCB for oxidative burst in granulocytes and the stimulation index were higher in mothers with preeclampsia than that of those with an SGA; however, the difference did not reach the statistical significance threshold set for this study (p = 0.02 and p = 0.03, respectively; see ).
Discussion
Principal findings of this study
(1) Women with SGA neonates had a significantly higher expression of CD11b in both granulocytes and monocytes than normal pregnant women; and (2) women with preeclampsia had a significantly lower expression of CD62L in granulocyte, and a significantly higher baseline iROS production and oxidative burst in monocytes than women with an SGA neonate.
Immunophenotypic and metabolic changes of leukocytes in pregnancy
It has been proposed that pregnancy is physiologically accompanied not only by the relative suppression of the adaptive limb of immunity, which would be necessary in order to sustain the fetal allograft but also by the activation of the innate immune system [Citation90]. A good example for this modification is the experimental Shwartzman reaction, which demonstrated that in pregnant animals monocytes are primed, as a single injection of lipopolysaccharide (LPS) is sufficient to induce disseminated intravascular coagulation and renal cortical necrosis, in contrast to non-pregnant animals in which two doses of LPS are required [Citation91–93]. In support of this hypothesis, peripheral leukocytes of women with normal pregnancies show significant changes in antigen expression and iROS concentration, which are akin to those observed in septic non-pregnant patients [Citation60]. Moreover, the expression of CD62L and CD11b as well as other leukocyte surface antigens (such as CD64, CD66b, CD15, CD14) have been found to be further altered in several pregnancy complications such as acute maternal infections [Citation81], spontaneous preterm labor [Citation82], preterm prelabor rupture of membranes [Citation83], and preeclampsia [Citation60,Citation64,Citation66], suggesting that all these obstetrical syndromes are characterized by different degrees of a systemic intra-vascular inflammatory response.
Immunophenotypic changes of leukocytes in women with a small-for-gestational age fetus
The finding of an increased expression of CD11b in granulocytes and monocytes of patients with an SGA fetus is consistent with a previous report by Sabatier et al. [Citation64]. CD11b is a subunit of the heterodimeric integrin αMβ2, also known as macrophage-1 antigen (Mac-1) or complement receptor 3 (CR3). The expression of CD11b is directly involved in leukocyte firm adhesion to the endothelium through interaction with the intercellular adhesion molecule 1 (ICAM-1), while the presence of the β2 subunit (CD18) is necessary to promote leukocyte migration [Citation94]. The expression of CD11b and that of the CD18/CD11b complex is considered as a sensitive marker of leukocyte activation in vivo [Citation88]. As this change was observed in granulocytes as well as monocytes in women with an SGA fetus, it is suggestive of increased leukocyte adherence to the vascular endothelium in this pregnancy complication. In support of our finding, Johnston et al. [Citation55] reported an increased concentration of neutrophil elastase, a protein released by activated neutrophils, in the plasma of women with an SGA fetus. Collectively, these data suggest that neutrophils of women with an SGA fetus differ from those of women with normal pregnancies in their phenotypic characteristics, which are associated with endothelial adherence and degranulation.
Small-for-gestational age and preeclampsia are associated with different immunophenotypes and metabolic activity of maternal leukocytes
Preeclampsia is associated with phenotypic and metabolic changes of granulocytes and monocytes in the maternal circulation. Indeed, a previous study by our group [Citation66] reported that granulocytes from women with preeclampsia had striking phenotypic and metabolic changes compared with those of women with a normal pregnancy. In particular, granulocytes of women who developed preeclampsia had a significantly higher median MCB of CD11b, lower MCB of CD62L, and increased oxidative burst, while their monocytes had a significantly higher median MCB for CD11b, basal iROS concentration, and oxidative burst than women with a normal pregnancy [Citation66]. Here, the expression of CD62L in granulocytes of women with preeclampsia was significantly lower than that of women with an SGA neonate. In contrast, the basal iROS production and oxidative burst of monocytes of patients with preeclampsia were higher than those of women with SGA fetuses. These findings are novel and suggest that leukocyte activation in women with SGA fetuses is quantitatively lower and qualitatively different than that of patients with preeclampsia.
The immunophenotypic differences in the leukocytes of patients with preeclampsia and those with an SGA fetus are mainly in the degree of CD62L expression by granulocytes. This surface marker, also known as L-selectin, is constitutively expressed on the surface of most leukocytes. The interactions of CD62L with its endothelial ligands are involved in the initial capture and subsequent rolling of leukocytes along the blood vessels that perfuse sites of inflammation. Rolling allows leukocytes to sense pro-inflammatory cytokines and chemokines produced by activated endothelial cells and is a prerequisite step for firm adhesion to endothelium mediated by the expression of integrins such us CD18/CD11b, and migration into the interstitial tissue[Citation95]. L-selectin is rapidly shed from leukocytes upon activation [Citation96], through the cleavage of the extracellular domain by the A Disintegrin And Metalloprotease-17 (ADAM-17) [Citation89]. Therefore, the down-regulation of CD62L is consistent with leukocyte activation although it can also be caused by other factors such as exposure to hyper- or hypotonic media and shear stress [Citation89].
The greater production of ROS found in preeclampsia is particularly intriguing as oxidative stress is likely to play a role in determining or amplifying endothelial dysfunction [Citation97–103]; however, the causal–effect relationship has not been clarified, and attempts to prevent preeclampsia or its complications by supplementation of antioxidant during pregnancy have led to disappointing results [Citation104–107].
Trophoblasts have been found to inhibit, in a contact-dependent manner, the production and releasing of ROS by neutrophils [Citation108]; this effect is mediated by the inactivation of the hexose monophosphate shunt which, in turn, is necessary for the generation of NAD(P)H and the production of superoxide [Citation108]. Of interest, our group has demonstrated that patients with preeclampsia have a greater proportion of neutrophils with high NAD(P)H production than normal pregnant women, both in basal condition and after stimulation with LPS [Citation109]. This finding indicates that the trophoblasts of patients with preeclampsia fail to block the production of ROS by activated leukocytes. It is possible that differences in the properties of the trophoblasts between patients with preeclampsia and those who have an SGA fetus are the cause of the diversity in the basal iROS concentration and the oxidative burst that we have observed in the present study. However, differences in the ability to deactivate leukocytes between trophoblasts from women with preeclampsia and women delivering an SGA neonate have not been investigated.
Small-for-gestational age and preeclampsia are associated with a different profile and intensity of maternal systemic response
Our results suggest that pregnancies with SGA fetuses are characterized by a higher activation of maternal peripheral leukocytes than normal pregnancies but lower than in pregnancies complicated by preeclampsia. As discussed below, such a conclusion is consistent with previous reports regarding other aspects of the maternal systemic response, which appears to be lower or different in pregnancies complicated by an SGA fetus than in those with preeclampsia. During a systemic inflammatory response, there is an increase in pro-inflammatory cytokines, activation of the coagulation cascade and angiogenesis [Citation110]. These three inter-dependent events are part of the process by which the organism reacts to injury and threat. Evidence of the dysregulation of these mechanisms in preeclampsia and in an SGA is the following:
Changes in the markers of inflammation in preeclampsia and small-for-gestational age.
Differences in the circulating maternal concentration of many pro-inflammatory cytokines have been reported in patients with preeclampsia in comparison to women with an SGA fetus. Maternal tumor necrosis factor (TNF)-α and its soluble receptor sTNF-R1 are elevated in patients with preeclampsia [Citation69,Citation78], but TNF-α has been found either to be increased [Citation111] or decreased [Citation112] in mothers of SGA fetuses. In comparison to normal pregnant women, patients with preeclampsia [Citation69,Citation77], but not women with an SGA neonate [Citation69,Citation111], had higher circulating interleukin (IL)- 6 and IL-8 concentrations. The median plasma concentration of the inflammatory molecule Pentraxin 3 is significantly increased in pregnancies complicated with preeclampsia but not in those complicated with intrauterine growth restriction [Citation73]. The complement split products profile also differs between the two syndromes, as higher concentrations of C5a have been found in preeclampsia, whereas lower concentrations of C4a were associated with SGA, in comparison to normal pregnancy [Citation113].
Changes in hemostatic activity and thrombin generation in preeclampsia and small-for-gestational age.
Both obstetrical syndromes are associated with increased in vivo thrombin generation in comparison to normal pregnancy [Citation114–122]. However, the concentration and the activity of specific components of the coagulation cascade differ between women with preeclampsia and those with an SGA fetus. Indeed, maternal plasma tissue factor (TF), the major activator of the coagulation cascade, is higher in women with preeclampsia and lower in mothers of an SGA fetus compared with normal pregnancies [Citation79]; moreover, the ratio between maternal plasma TF and its natural inhibitor was significantly lower among patients with preeclampsia than in those with normal pregnancy as well as in those who delivered an SGA neonate [Citation79]. Monocyte activation is associated with secretion of TF in the maternal circulation [Citation123–129] and this process is mediated by the production of the ROS superoxide anion (O2−) and the activation of the transcription factor nuclear factor-κB (NF-κB) [Citation129–132]. It is possible that the loss of inhibition of leukocyte ROS production by the trophoblasts of women with preeclampsia [Citation109] can also account, at least in part, for the high plasma tissue factor concentration. This process may not be so prominent in pregnancies with SGA fetuses.
Angiogenic and anti-angiogenic state in preeclampsia and small-for-gestational age.
Both preeclampsia and SGA are characterized by an anti-angiogenic state, indicated by decreased concentration of the pro-angiogenic factor placental growth factor (PlGF) [Citation30,Citation32,Citation34–36,Citation41,Citation44,Citation47] and increased concentrations of the anti-angiogenic factors soluble vascular endothelial growth factor receptor (sVEGFR)- 1 [Citation29,Citation30,Citation32–36,Citation41,Citation42,Citation44] and soluble endoglin (sEng) [Citation31,Citation37–39,Citation41,Citation44,Citation46,Citation48–50]. However, each obstetrical syndrome seems to have a unique pattern of angiogenic and anti-angiogenic factors during the course of pregnancy. The following solid body of evidence supports this view: (1) women destined to deliver an SGA neonate have a higher plasma concentration of sEng than controls since the first trimester, while similar changes occur only after 23 weeks of gestation in women who develop preterm preeclampsia and after 30 weeks in those who develop term preeclampsia [Citation41]; (2) maternal plasma PlGF concentrations are lower than in normal pregnancy, both in women with SGA neonates and in those with preeclampsia, throughout gestation [Citation30,Citation41]; however, those destined to develop preterm preeclampsia have an earlier decline of maternal plasma PlGF concentrations than those destined to develop preeclampsia at term or to deliver an SGA neonate [Citation41]; and (3) an increase in maternal plasma sVEGFR-1 between the first and the second trimester is associated with an increased risk to develop preterm preeclampsia but not an SGA without hypertension [Citation40,Citation44].
Strengths and limitations of the study
The main strength of this study lies in the sample size (99 subjects), which is the largest among flow cytometry studies performed in pregnancies complicated by SGA or preeclampsia [Citation60,Citation76,Citation125,Citation133]. However, two potential limitations should be considered: first, the cross-sectional design of the study does not allow us to demonstrate neither a temporal nor a causal relationship between the observed changes in the immunophenotype and metabolic characteristics of maternal leukocytes and these pregnancy complications. The second limitation depends on the adoption of a low p-value for statistical significance (< 0.01). Such a strict criterion increases the possibility of a type II error, potentially preventing us to demonstrate some existing phenotypic and metabolic differences between the study groups. However, this approach was chosen to correct for multiple comparisons, and thereby it actually reduces the risk of type I error (reporting that a difference exist while, in fact, there is no difference).
In summary, abnormal placentation has been proposed to play a major role in the activation of the maternal intra-vascular systemic inflammatory response through the release of soluble factors (i.e. inflammatory cytokines [Citation134–137], anti-angiogenic factors [Citation29,Citation138,Citation139], and free-radical species [Citation19,Citation100,Citation140–142]) or particles (syncytiotrophoblast microparticles [Citation143,Citation144]) into the maternal circulation. While the histological findings in the placentae of pregnancies complicated by preeclampsia or SGA are similar [Citation4,Citation6], the pattern of the maternal systemic inflammatory response differs. Our findings of a diverse profile of leukocyte activation, along with the discrepancies in other features of systemic inflammatory response, support the hypothesis that SGA and preeclampsia are two distinct entities.
Acknowledgments
This research was supported by the Perinatology Research Branch, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, DHHS.
References
- Romero R. Prenatal medicine: the child is the father of the man. Prenat Neonatal Med 1996;1:8–11.
- ACOG practice bulletin. Diagnosis and management of preeclampsia and eclampsia. Obstet Gynecol 2002;99:159–167.
- De Wolf F, Brosens I, Renaer M. Fetal growth retardation and the maternal arterial supply of the human placenta in the absence of sustained hypertension. Br J Obstet Gynaecol 1980;87:678–685.
- Hustin J, Foidart JM, Lambotte R. Maternal vascular lesions in pre-eclampsia and intrauterine growth retardation: light microscopy and immunofluorescence. Placenta 1983;4 Spec No:489–498.
- Labarrere C, Alonso J, Manni J, Domenichini E, Althabe O. Immunohistochemical findings in acute atherosis associated with intrauterine growth retardation. Am J Reprod Immunol Microbiol 1985;7:149–155.
- Khong TY, De WF, Robertson WB, Brosens I. Inadequate maternal vascular response to placentation in pregnancies complicated by pre-eclampsia and by small-for-gestational age infants. Br J Obstet Gynaecol 1986;93:1049–1059.
- Pijnenborg R, Anthony J, Davey DA, Rees A, Tiltman A, Vercruysse L, van AA. Placental bed spiral arteries in the hypertensive disorders of pregnancy. Br J Obstet Gynaecol 1991;98:648–655.
- Meekins JW, Pijnenborg R, Hanssens M, McFadyen IR, van AA. A study of placental bed spiral arteries and trophoblast invasion in normal and severe pre-eclamptic pregnancies. Br J Obstet Gynaecol 1994;101:669–674.
- Robertson WB, Brosens I, Dixon G. Maternal uterine vascular lesions in the hypertensive complications of pregnancy. Perspect Nephrol Hypertens 1976;5:115–127.
- Brosens IA. Morphological changes in the utero-placental bed in pregnancy hypertension. Clin Obstet Gynaecol 1977;4:573–593.
- Sheppard BL, Bonnar J. An ultrastructural study of utero-placental spiral arteries in hypertensive and normotensive pregnancy and fetal growth retardation. Br J Obstet Gynaecol 1981;88:695–705.
- Campbell S, Diaz-Recasens J, Griffin DR, Cohen-Overbeek TE, Pearce JM, Willson K, Teague MJ. New doppler technique for assessing uteroplacental blood flow. Lancet 1983;1:675–677.
- Roberts JM, Taylor RN, Musci TJ, Rodgers GM, Hubel CA, McLaughlin MK. Preeclampsia: an endothelial cell disorder. Am J Obstet Gynecol 1989;161:1200–1204.
- Harrington KF, Campbell S, Bewley S, Bower S. Doppler velocimetry studies of the uterine artery in the early prediction of pre-eclampsia and intra-uterine growth retardation. Eur J Obstet Gynecol Reprod Biol 1991;42Suppl: S14–S20.
- Clark BA, Halvorson L, Sachs B, Epstein FH. Plasma endothelin levels in preeclampsia: elevation and correlation with uric acid levels and renal impairment. Am J Obstet Gynecol 1992;166:962–968.
- Harrington K, Cooper D, Lees C, Hecher K, Campbell S. Doppler ultrasound of the uterine arteries: the importance of bilateral notching in the prediction of pre-eclampsia, placental abruption or delivery of a small-for-gestational-age baby. Ultrasound Obstet Gynecol 1996;7:182–188.
- Conrad KP, Benyo DF. Placental cytokines and the pathogenesis of preeclampsia. Am J Reprod Immunol 1997;37:240–249.
- Dekker GA, Sibai BM. Etiology and pathogenesis of preeclampsia: current concepts. Am J Obstet Gynecol 1998;179:1359–1375.
- Roberts JM. Endothelial dysfunction in preeclampsia. Semin Reprod Endocrinol 1998;16:5–15.
- Taylor RN, de Groot CJ, Cho YK, Lim KH. Circulating factors as markers and mediators of endothelial cell dysfunction in preeclampsia. Semin Reprod Endocrinol 1998;16:17–31.
- Albaiges G, Missfelder-Lobos H, Lees C, Parra M, Nicolaides KH. One-stage screening for pregnancy complications by color Doppler assessment of the uterine arteries at 23 weeks' gestation. Obstet Gynecol 2000;96:559–564.
- Papageorghiou AT, Yu CK, Bindra R, Pandis G, Nicolaides KH. Multicenter screening for pre-eclampsia and fetal growth restriction by transvaginal uterine artery Doppler at 23 weeks of gestation. Ultrasound Obstet Gynecol 2001;18:441–449.
- Poston L, Chappell LC. Is oxidative stress involved in the aetiology of pre-eclampsia? Acta Paediatr Suppl 2001;90:3–5.
- Granger JP, Alexander BT, Llinas MT, Bennett WA, Khalil RA. Pathophysiology of preeclampsia: linking placental ischemia/hypoxia with microvascular dysfunction. Micro circulation 2002;9:147–160.
- Myatt L. Role of placenta in preeclampsia. Endocrine 2002;19:103–111.
- Kadyrov M, Schmitz C, Black S, Kaufmann P, Huppertz B. Pre-eclampsia and maternal anaemia display reduced apoptosis and opposite invasive phenotypes of extravillous trophoblast. Placenta 2003;24:540–548.
- Fisher SJ. The placental problem: linking abnormal cytotrophoblast differentiation to the maternal symptoms of preeclampsia. Reprod Biol Endocrinol 2004;2:53.
- Papageorghiou AT, Yu CK, Nicolaides KH. The role of uterine artery Doppler in predicting adverse pregnancy outcome. Best Pract Res Clin Obstet Gynaecol 2004;18:383–396.
- Maynard SE, Min JY, Merchan J, Lim KH, Li J, Mondal S, Libermann TA, Morgan JP, Sellke FW, Stillman IE. et al Excess placental soluble fms-like tyrosine kinase 1 (sFlt1) may contribute to endothelial dysfunction, hypertension, and proteinuria in preeclampsia. J Clin Invest 2003;111:649–658.
- Levine RJ, Maynard SE, Qian C, Lim KH, England LJ, Yu KF, Schisterman EF, Thadhani R, Sachs BP, Epstein FH. et al Circulating angiogenic factors and the risk of preeclampsia. N Engl J Med 2004;350:672–683.
- Levine RJ, Lam C, Qian C, Yu KF, Maynard SE, Sachs BP, Sibai BM, Epstein FH, Romero R, Thadhani R. et al Soluble endoglin and other circulating antiangiogenic factors in preeclampsia. N Engl J Med 2006;355:992–1005.
- Crispi F, Dominguez C, Llurba E, Martin-Gallan P, Cabero L, Gratacos E. Placental angiogenic growth factors and uterine artery Doppler findings for characterization of different subsets in preeclampsia and in isolated intrauterine growth restriction. Am J Obstet Gynecol 2006;195:201–207.
- Wallner W, Sengenberger R, Strick R, Strissel PL, Meurer B, Beckmann MW, Schlembach D. Angiogenic growth factors in maternal and fetal serum in pregnancies complicated by intrauterine growth restriction. Clin Sci (Lond) 2007;112:51–57.
- Schlembach D, Wallner W, Sengenberger R, Stiegler E, Mortl M, Beckmann MW, Lang U. Angiogenic growth factor levels in maternal and fetal blood: correlation with Doppler ultrasound parameters in pregnancies complicated by pre-eclampsia and intrauterine growth restriction. Ultrasound Obstet Gynecol 2007;29:407–413.
- Wikstrom AK, Larsson A, Eriksson UJ, Nash P, Norden-Lindeberg S, Olovsson M. Placental growth factor and soluble FMS-like tyrosine kinase-1 in early-onset and late-onset preeclampsia. Obstet Gynecol 2007;109:1368–1374.
- Stepan H, Unversucht A, Wessel N, Faber R. Predictive value of maternal angiogenic factors in second trimester pregnancies with abnormal uterine perfusion. Hypertension 2007;49:818–824.
- Stepan H, Kramer T, Faber R. Maternal plasma concentrations of soluble endoglin in pregnancies with intrauterine growth restriction. J Clin Endocrinol Metab 2007;92:2831–2834.
- Staff AC, Braekke K, Johnsen GM, Karumanchi SA, Harsem NK. Circulating concentrations of soluble endoglin (CD105) in fetal and maternal serum and in amniotic fluid in preeclampsia. Am J Obstet Gynecol 2007;197:176.
- Robinson CJ, Johnson DD. Soluble endoglin as a second-trimester marker for preeclampsia. Am J Obstet Gynecol 2007;197:174–175.
- Vatten LJ, Eskild A, Nilsen TI, Jeansson S, Jenum PA, Staff AC. Changes in circulating level of angiogenic factors from the first to second trimester as predictors of preeclampsia. Am J Obstet Gynecol 2007;196:239.e1–239.e6.
- Romero R, Nien JK, Espinoza J, Todem D, Fu W, Chung H, Kusanovic JP, Gotsch F, Erez O, Mazaki-Tovi S. et al A longitudinal study of angiogenic (placental growth factor) and anti-angiogenic (soluble endoglin and soluble vascular endothelial growth factor receptor-1) factors in normal pregnancy and patients destined to develop preeclampsia and deliver a small for gestational age neonate. J Matern Fetal Neonatal Med 2008;21:9–23.
- Chaiworapongsa T, Espinoza J, Gotsch F, Kim YM, Kim GJ, Goncalves LF, Edwin S, Kusanovic JP, Erez O, Than NG. et al The maternal plasma soluble vascular endothelial growth factor receptor-1 concentration is elevated in SGA and the magnitude of the increase relates to Doppler abnormalities in the maternal and fetal circulation. J Matern Fetal Neonatal Med 2008;21:25–40.
- Chaiworapongsa T, Romero R, Gotsch F, Espinoza J, Nien JK, Goncalves L, Edwin S, Kim YM, Erez O, Kusanovic JP. et al Low maternal concentrations of soluble vascular endothelial growth factor receptor-2 in preeclampsia and small for gestational age. J Matern Fetal Neonatal Med 2008;21:41–52.
- Erez O, Romero R, Espinoza J, Fu W, Todem D, Kusanovic JP, Gotsch F, Edwin S, Nien JK, Chaiworapongsa T. et al The change in concentrations of angiogenic and anti-angiogenic factors in maternal plasma between the first and second trimesters in risk assessment for the subsequent development of preeclampsia and small-for-gestational age. J Matern Fetal Neonatal Med 2008;21:279–287.
- Gotsch F, Romero R, Kusanovic JP, Chaiworapongsa T, Dombrowski M, Erez O, Than NG, Mazaki-Tovi S, Mittal P, Espinoza J. et al Preeclampsia and small-for-gestational age are associated with decreased concentrations of a factor involved in angiogenesis: soluble Tie-2. J Matern Fetal Neonatal Med 2008;21:389–402.
- Baumann MU, Bersinger NA, Mohaupt MG, Raio L, Gerber S, Surbek DV. First-trimester serum levels of soluble endoglin and soluble fms-like tyrosine kinase-1 as first-trimester markers for late-onset preeclampsia. Am J Obstet Gynecol 2008;199:266.
- Crispi F, Llurba E, Dominguez C, Martin-Gallan P, Cabero L, Gratacos E. Predictive value of angiogenic factors and uterine artery Doppler for early- versus late-onset pre-eclampsia and intrauterine growth restriction. Ultrasound Obstet Gynecol 2008;31:303–309.
- De Vivo A, Baviera G, Giordano D, Todarello G, Corrado F, D'anna R. Endoglin, PlGF and sFlt-1 as markers for predicting pre-eclampsia. Acta Obstet Gynecol Scand 2008;87:837–842.
- Yinon Y, Nevo O, Xu J, Many A, Rolfo A, Todros T, Post M, Caniggia I. Severe intrauterine growth restriction pregnancies have increased placental endoglin levels: hypoxic regulation via transforming growth factor-beta 3. Am J Pathol 2008;172:77–85.
- Chedraui P, Lockwood CJ, Schatz F, Buchwalder LF, Schwager G, Guerrero C, Escobar GS, Hidalgo L. Increased plasma soluble fms-like tyrosine kinase 1 and endoglin levels in pregnancies complicated with preeclampsia. J Matern Fetal Neonatal Med 2009;22:565–570.
- Kusanovic JP, Romero R, Chaiworapongsa T, Erez O, Mittal P, Vaisbuch E, Mazaki-Tovi S, Gotsch F, Edwin SS, Gomez R. et al A prospective cohort study of the value of the maternal plasma concentration of angiogenic and anti-angiogenic factors in early pregnancy and midtrimester in the identification of patients destined to develop preeclampsia. J Matern Fetal Neonatal Med 2009; in press.
- Ishihara N, Matsuo H, Murakoshi H, Laoag-Fernandez JB, Samoto T, Maruo T. Increased apoptosis in the syncytiotrophoblast in human term placentas complicated by either preeclampsia or intrauterine growth retardation. Am J Obstet Gynecol 2002;186:158–166.
- Labarrere C, Manni J, Salas P, Althabe O. Intrauterine growth retardation of unknown etiology. I. Serum complement and circulating immune complexes in mothers and infants. Am J Reprod Immunol Microbiol 1985;8:87–93.
- Labarrere CA, Althabe OH. Intrauterine growth retardation of unknown etiology. II. Serum complement and circulating immune complexes in maternal sera and their relationship with parity and chronic villitis. Am J Reprod Immunol Microbiol 1986;12:4–6.
- Johnston TA, Greer IA, Dawes J, Calder AA. Neutrophil activation in small for gestational age pregnancies. Br J Obstet Gynaecol 1991;98:105–106.
- Haeger M, Unander M, Norder-Hansson B, Tylman M, Bengtsson A. Complement, neutrophil, and macrophage activation in women with severe preeclampsia and the syndrome of hemolysis, elevated liver enzymes, and low platelet count. Obstet Gynecol 1992;79:19–26.
- Vince GS, Starkey PM, Austgulen R, Kwiatkowski D, Redman CW. Interleukin-6, tumour necrosis factor and soluble tumour necrosis factor receptors in women with pre-eclampsia. Br J Obstet Gynaecol 1995;102:20–25.
- Djurovic S, Schjetlein R, Wisloff F, Haugen G, Berg K. Increased levels of intercellular adhesion molecules and vascular cell adhesion molecules in pre-eclampsia. Br J Obstet Gynaecol 1997;104:466–470.
- Krauss T, Kuhn W, Lakoma C, Augustin HG. Circulating endothelial cell adhesion molecules as diagnostic markers for the early identification of pregnant women at risk for development of preeclampsia. Am J Obstet Gynecol 1997;177:443–449.
- Sacks GP, Studena K, Sargent K, Redman CW. Normal pregnancy and preeclampsia both produce inflammatory changes in peripheral blood leukocytes akin to those of sepsis. Am J Obstet Gynecol 1998;179:80–86.
- von Dadelszen P, Wilkins T, Redman CW. Maternal peripheral blood leukocytes in normal and pre-eclamptic pregnancies. Br J Obstet Gynaecol 1999;106:576–581.
- Redman CW, Sacks GP, Sargent IL. Preeclampsia: an excessive maternal inflammatory response to pregnancy. Am J Obstet Gynecol 1999;180:499–506.
- Kobayashi N, Yamada H, Kishida T, Kato EH, Ebina Y, Sakuragi N, Kobashi G, Tsutsumi A, Fujimoto S. Hypocomplementemia correlates with intrauterine growth retardation in systemic lupus erythematosus. Am J Reprod Immunol 1999;42:153–159.
- Sabatier F, Bretelle F, D'ercole C, Boubli L, Sampol J, gnat-George F. Neutrophil activation in preeclampsia and isolated intrauterine growth restriction. Am J Obstet Gynecol 2000;183:1558–1563.
- de Messias-Reason IJ, Aleixo V, de FH, Nisihara RM, Mocelin V, Urbanetz A. Complement activation in Brazilian patients with preeclampsia. J Investig Allergol Clin Immunol 2000;10:209–214.
- Gervasi MT, Chaiworapongsa T, Pacora P, Naccasha N, Yoon BH, Maymon E, Romero R. Phenotypic and metabolic characteristics of monocytes and granulocytes in preeclampsia. Am J Obstet Gynecol 2001;185:792–797.
- Chaiworapongsa T, Gervasi MT, Refuerzo J, Espinoza J, Yoshimatsu J, Berman S, Romero R. Maternal lymphocyte subpopulations (CD45RA+ and CD45RO+) in preeclampsia. Am J Obstet Gynecol 2002;187:889–893.
- Kauma S, Takacs P, Scordalakes C, Walsh S, Green K, Peng T. Increased endothelial monocyte chemoattractant protein-1 and interleukin-8 in preeclampsia. Obstet Gynecol 2002;100:706–714.
- Johnson MR, nim-Nyame N, Johnson P, Sooranna SR, Steer PJ. Does endothelial cell activation occur with intrauterine growth restriction? BJOG 2002;109:836–839.
- Coata G, Pennacchi L, Bini V, Liotta L, Di Renzo GC. Soluble adhesion molecules: marker of pre-eclampsia and intrauterine growth restriction. J Matern Fetal Neonatal Med 2002;12:28–34.
- Tjoa ML, van Vugt JM, Go AT, Blankenstein MA, Oudejans CB, van Wijk IJ. Elevated C-reactive protein levels during first trimester of pregnancy are indicative of preeclampsia and intrauterine growth restriction. J Reprod Immunol 2003;59:29–37.
- Beckmann I, Efraim SB, Vervoort M, Visser W, Wallenburg HC. Tumor necrosis factor-alpha in whole blood cultures of preeclamptic patients and healthy pregnant and nonpregnant women. Hypertens Pregnancy 2004;23:319–329.
- Cetin I, Cozzi V, Pasqualini F, Nebuloni M, Garlanda C, Vago L, Pardi G, Mantovani A. Elevated maternal levels of the long pentraxin 3 (PTX3) in preeclampsia and intrauterine growth restriction. Am J Obstet Gynecol 2006;194:1347–1353.
- Girardi G, Yarilin D, Thurman JM, Holers VM, Salmon JE. Complement activation induces dysregulation of angiogenic factors and causes fetal rejection and growth restriction. J Exp Med 2006;203:2165–2175.
- Girardi G, Bulla R, Salmon JE, Tedesco F. The complement system in the pathophysiology of pregnancy. Mol Immunol 2006;43:68–77.
- Luppi P, Deloia JA. Monocytes of preeclamptic women spontaneously synthesize pro-inflammatory cytokines. Clin Immunol 2006;118:268–275.
- Laskowska M, Laskowska K, Leszczynska-Gorzelak B, Oleszczuk J. Comparative analysis of the maternal and umbilical interleukin-8 levels in normal pregnancies and in pregnancies complicated by preeclampsia with intrauterine normal growth and intrauterine growth retardation. J Matern Fetal Neonatal Med 2007;20:527–532.
- Laskowska M, Laskowska K, Leszczynska-Gorzelak B, Oleszczuk J. Maternal and umbilical sTNF-R1 in preeclamptic pregnancies with intrauterine normal and growth retarded fetus. Hypertens Pregnancy 2007;26:13–21.
- Erez O, Romero R, Hoppensteadt D, Than NG, Fareed J, Mazaki-Tovi S, Espinoza J, Chaiworapongsa T, Kim SS, Yoon BH. et al Tissue factor and its natural inhibitor in pre-eclampsia and SGA. J Matern Fetal Neonatal Med 2008;21:855–869.
- Friedman SA, de Groot CJ, Taylor RN, Golditch BD, Roberts JM. Plasma cellular fibronectin as a measure of endothelial involvement in preeclampsia and intrauterine growth retardation. Am J Obstet Gynecol 1994;170:838–841.
- Naccasha N, Gervasi MT, Chaiworapongsa T, Berman S, Yoon BH, Maymon E, Romero R. Phenotypic and metabolic characteristics of monocytes and granulocytes in normal pregnancy and maternal infection. Am J Obstet Gynecol 2001;185:1118–1123.
- Gervasi MT, Chaiworapongsa T, Naccasha N, Blackwell S, Yoon BH, Maymon E, Romero R. Phenotypic and metabolic characteristics of maternal monocytes and granulocytes in preterm labor with intact membranes. Am J Obstet Gynecol 2001;185:1124–1129.
- Gervasi MT, Chaiworapongsa T, Naccasha N, Pacora P, Berman S, Maymon E, Kim JC, Kim YM, Yoshimatsu J, Espinoza J. et al Maternal intravascular inflammation in preterm premature rupture of membranes. J Matern Fetal Neonatal Med 2002;11:171–175.
- Alexander GR, Himes JH, Kaufman RB, Mor J, Kogan M. A United States national reference for fetal growth. Obstet Gynecol 1996;87:163–168.
- McCarthy DA, Macey MG. A simple flow cytometric procedure for the determination of surface antigens on unfixed leucocytes in whole blood. J Immunol Methods 1993;163:155–160.
- McCarthy DA, Macey MG. Novel anticoagulants for flow cytometric analysis of live leucocytes in whole blood. Cytometry 1996;23:196–204.
- Himmelfarb J, Hakim RM, Holbrook DG, Leeber DA, Ault KA. Detection of granulocyte reactive oxygen species formation in whole blood using flow cytometry. Cytometry 1992;13:83–89.
- van Eeden SF, Klut ME, Walker BA, Hogg JC. The use of flow cytometry to measure neutrophil function. J Immunol Methods 1999;232:23–43.
- Lee D, Schultz JB, Knauf PA, King MR. Mechanical shedding of L-selectin from the neutrophil surface during rolling on sialyl Lewis × under flow. J Biol Chem 2007;282:4812–4820.
- Sacks G, Sargent I, Redman C. An innate view of human pregnancy. Immunol Today 1999;20:114–118.
- Muller-Berghaus G, Schmidt-Ehry B. The role of pregnancy in the induction of the generalized Shwartzman reaction. Am J Obstet Gynecol 1972;114:847–849.
- Muller-Berghaus G, Obst R. Induction of the generalized Shwartzman reaction in pregnant and nonpregnant rats by colchicine. Am J Pathol 1972;69:131–138.
- Mori W. The Shwartzman reaction: a review including clinical manifestations and proposal for a univisceral or single organ third type. Histopathology 1981;5:113–126.
- Solovjov DA, Pluskota E, Plow EF. Distinct roles for the alpha and beta subunits in the functions of integrin alphaMbeta2. J Biol Chem 2005;280:1336–1345.
- Ivetic A, Ridley AJ. The telling tail of L-selectin. Biochem Soc Trans 2004;32:1118–1121.
- Kishimoto TK, Jutila MA, Berg EL, Butcher EC. Neutrophil Mac-1 and MEL-14 adhesion proteins inversely regulated by chemotactic factors. Science 1989;245:1238–1241.
- Mikhail MS, Anyaegbunam A, Garfinkel D, Palan PR, Basu J, Romney SL. Preeclampsia and antioxidant nutrients: decreased plasma levels of reduced ascorbic acid, alpha-tocopherol, and beta-carotene in women with preeclampsia. Am J Obstet Gynecol 1994;171:150–157.
- Barden A, Beilin LJ, Ritchie J, Croft KD, Walters BN, Michael CA. Plasma and urinary 8-iso-prostane as an indicator of lipid peroxidation in pre-eclampsia and normal pregnancy. Clin Sci (Lond) 1996;91:711–718.
- Hubel CA, McLaughlin MK, Evans RW, Hauth BA, Sims CJ, Roberts JM. Fasting serum triglycerides, free fatty acids, and malondialdehyde are increased in preeclampsia, are positively correlated, and decrease within 48 hours post partum. Am J Obstet Gynecol 1996;174:975–982.
- Hubel CA. Dyslipidemia, iron, and oxidative stress in preeclampsia: assessment of maternal and feto-placental interactions. Semin Reprod Endocrinol 1998;16:75–92.
- Davidge ST. Oxidative stress and altered endothelial cell function in preeclampsia. Semin Reprod Endocrinol 1998;16:65–73.
- Zhang Y, Zhao S, Gu Y, Lewis DF, Alexander JS, Wang Y. Effects of peroxynitrite and superoxide radicals on endothelial monolayer permeability: potential role of peroxynitrite in preeclampsia. J Soc Gynecol Investig 2005;12:586–592.
- Afzal-Ahmed I, Mann GE, Shennan AH, Poston L, Naftalin RJ. Preeclampsia inactivates glucose-6-phosphate dehydrogenase and impairs the redox status of erythrocytes and fetal endothelial cells. Free Radic Biol Med 2007;42:1781–1790.
- Poston L, Briley AL, Seed PT, Kelly FJ, Shennan AH. Vitamin C and vitamin E in pregnant women at risk for pre-eclampsia (VIP trial): randomised placebo-controlled trial. Lancet 2006;367:1145–1154.
- Romero R, Garite TJ. Unexpected results of an important trial of vitamins C and E administration to prevent preeclampsia. Am J Obstet Gynecol 2006;194:1213–1214.
- Rumbold A, Duley L, Crowther CA, Haslam RR. Anti oxidants for preventing pre-eclampsia. Cochrane Database Syst Rev 2008;1:CD004227.
- Roberts JM. A randomized controlled trial of antioxidant vitamins to prevent serious complications associated with pregnancy related hypertension in low risk, nulliparous women. Am J Obstet Gynecol 2009;199:S4.
- Petty HR, Kindzelskii AL, Espinoza J, Romero R. Trophoblast contact deactivates human neutrophils. J Immunol 2006;176:3205–3214.
- Espinoza J, Kindzelski A, Kusanovic JP, Chaiworapongsa T, Hassan S, Yoon BH, Petty H, Romero R. Preeclampsia is characterized by a large number of neutrophils displaying a high amplitude of NAD(P)H metabolic oscillations: a link between intravascular inflammation,endothelial cell dysfunction and preeclampsia. Am J Obstet Gynecol 2006;195:S147.
- Danese S, Dejana E, Fiocchi C. Immune regulation by microvascular endothelial cells: directing innate and adaptive immunity, coagulation, and inflammation. J Immunol 2007;178:6017–6022.
- Bartha JL, Romero-Carmona R, Comino-Delgado R. Inflammatory cytokines in intrauterine growth retardation. Acta Obstet Gynecol Scand 2003;82:1099–1102.
- Schiff E, Friedman SA, Baumann P, Sibai BM, Romero R. Tumor necrosis factor-alpha in pregnancies associated with preeclampsia or small-for-gestational-age newborns. Am J Obstet Gynecol 1994;170:1224–1229.
- Richani K, Soto E, Romero R, Espinoza J, Chaiworapongsa T, Nien JK, Edwin SS, Kim YM, Hong JS, Goncalves L, et al Preeclampsia and SGA differ in the maternal plasma complement splict products profile. J Soc Gynecol Investig 2005;12:148A.
- Reinthaller A, Mursch-Edlmayr G, Tatra G. Thrombin-antithrombin III complex levels in normal pregnancy with hypertensive disorders and after delivery. Br J Obstet Gynaecol 1990;97:506–510.
- Terao T, Maki M, Ikenoue T, Gotoh K, Murata M, Iwasaki H, Shibata J, Nakabayashi M, Muraoka M, Takeda Y. The relationship between clinical signs and hypercoagulable state in toxemia of pregnancy. Gynecol Obstet Invest 1991;31:74–85.
- Cadroy Y, Grandjean H, Pichon J, Desprats R, Berrebi A, Fournie A, Boneu B. Evaluation of six markers of haemostatic system in normal pregnancy and pregnancy complicated by hypertension or pre-eclampsia. Br J Obstet Gynaecol 1993;100:416–420.
- Halligan A, Bonnar J, Sheppard B, Darling M, Walshe J. Haemostatic, fibrinolytic and endothelial variables in normal pregnancies and pre-eclampsia. Br J Obstet Gynaecol 1994;101:488–492.
- Schjetlein R, Haugen G, Wisloff F. Markers of intravascular coagulation and fibrinolysis in preeclampsia: association with intrauterine growth retardation. Acta Obstet Gynecol Scand 1997;76:541–546.
- Bellart J, Gilabert R, Fontcuberta J, Carreras E, Miralles RM, Cabero L. Coagulation and fibrinolytic parameters in normal pregnancy and in pregnancy complicated by intra uterine growth retardation. Am J Perinatol 1998;15:81–85.
- Schjetlein R, Abdelnoor M, Haugen G, Husby H, Sandset PM, Wisloff F. Hemostatic variables as independent predictors for fetal growth retardation in preeclampsia. Acta Obstet Gynecol Scand 1999;78:191–197.
- Chaiworapongsa T, Yoshimatsu J, Espinoza J, Kim YM, Berman S, Edwin S, Yoon BH, Romero R. Evidence of in vivo generation of thrombin in patients with small-for-gestational-age fetuses and pre-eclampsia. J Matern Fetal Neonatal Med 2002;11:362–367.
- Erez O, Romero R, Kim SS, Kim JS, Kim YM, Wildman DE, Than NG, Mazaki-Tovi S, Gotsch F, Pineles B, et al Over-expression of the thrombin receptor (PAR-1) in the placenta in preeclampsia: a mechanism for the intersection of coagulation and inflammation. J Matern Fetal Neonatal Med 2008;21:345–355.
- Satta N, Toti F, Feugeas O, Bohbot A, chary-Prigent J, Eschwege V, Hedman H, Freyssinet JM. Monocyte vesiculation is a possible mechanism for dissemination of membrane-associated procoagulant activities and adhesion molecules after stimulation by lipopolysaccharide. J Immunol 1994;153:3245–3255.
- Osterud B. The role of platelets in decrypting monocyte tissue factor. Semin Hematol 2001;38:2–5.
- Sabatier F, Roux V, Anfosso F, Camoin L, Sampol J, gnat-George F. Interaction of endothelial microparticles with monocytic cells in vitro induces tissue factor-dependent procoagulant activity. Blood 2002;99:3962–3970.
- Shet AS, Aras O, Gupta K, Hass MJ, Rausch DJ, Saba N, Koopmeiners L, Key NS, Hebbel RP. Sickle blood contains tissue factor-positive microparticles derived from endothelial cells and monocytes. Blood 2003;102:2678–2683.
- Eilertsen KE, Osterud B. The role of blood cells and their microparticles in blood coagulation. Biochem Soc Trans 2005;33:418–422.
- Osterud B, Bjorklid E. Sources of tissue factor. Semin Thromb Hemost 2006;32:11–23.
- Poitevin S, Garnotel R, Antonicelli F, Gillery P, Nguyen P. Type I collagen induces tissue factor expression and matrix metalloproteinase 9 production in human primary monocytes through a redox-sensitive pathway. J Thromb Haemost 2008;6:1586–1594.
- Brisseau GF, Dackiw AP, Cheung PY, Christie N, Rotstein OD. Posttranscriptional regulation of macrophage tissue factor expression by antioxidants. Blood 1995;85:1025–1035.
- Polack B, Pernod G, Barro C, Doussiere J. Role of oxygen radicals in tissue factor induction by endotoxin in blood monocytes. Haemostasis 1997;27:193–200.
- Cadroy Y, Dupouy D, Boneu B, Plaisancie H. Polymorphonuclear leukocytes modulate tissue factor production by mononuclear cells: role of reactive oxygen species. J Immunol 2000;164:3822–3828.
- Mellembakken JR, Aukrust P, Olafsen MK, Ueland T, Hestdal K, Videm V. Activation of leukocytes during the uteroplacental passage in preeclampsia. Hypertension 2002;39:155–160.
- Benyo DF, Miles TM, Conrad KP. Hypoxia stimulates cytokine production by villous explants from the human placenta. J Clin Endocrinol Metab 1997;82:1582–1588.
- Munno I, Chiechi LM, Lacedra G, Putignano G, Patimo C, Lobascio A, Loizzi P. Spontaneous and induced release of prostaglandins, interleukin (IL)- 1beta, IL-6, and tumor necrosis factor-α by placental tissue from normal and preeclamptic pregnancies. Am J Reprod Immunol 1999;42:369–374.
- Rinehart BK, Terrone DA, Lagoo-Deenadayalan S, Barber WH, Hale EA, Martin JN Jr, Bennett WA. Expression of the placental cytokines tumor necrosis factor alpha, interleukin 1beta, and interleukin 10 is increased in preeclampsia. Am J Obstet Gynecol 1999;181:915–920.
- Wang Y, Walsh SW. TNF alpha concentrations and mRNA expression are increased in preeclamptic placentas. J Reprod Immunol 1996;32:157–169.
- Karumanchi SA, Bdolah Y. Hypoxia and sFlt-1 in preeclampsia: the ‘chicken-and-egg’ question. Endocrinology 2004;145:4835–4837.
- Kita N, Mitsushita J. A possible placental factor for preeclampsia: sFlt-1. Curr Med Chem 2008;15:711–715.
- Many A, Hubel CA, Fisher SJ, Roberts JM, Zhou Y. Invasive cytotrophoblasts manifest evidence of oxidative stress in preeclampsia. Am J Pathol 2000;156:321–331.
- Roberts JM, Hubel CA. Is oxidative stress the link in the two-stage model of pre-eclampsia? Lancet 1999;354:788–789.
- Wang Y, Walsh SW, Kay HH. Placental lipid peroxides and thromboxane are increased and prostacyclin is decreased in women with preeclampsia. Am J Obstet Gynecol 1992;167:946–949.
- Redman CW, Sargent IL. Latest advances in understanding preeclampsia. Science 2005;308:1592–1594.
- Redman CW, Sargent IL. Microparticles and immunomodulation in pregnancy and pre-eclampsia. J Reprod Immunol 2007;76:61–67.