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Serum Levels of Vascular Endothelial Growth Factor in Preeclamptic and Normotensive Pregnancy
Abstract
The purpose of these studies was first to determine if vascular endothelial growth factor (VEGF), a vascular permeability agent, is increased in the serum of women with preclinical and clinical preclampsia (PE), and second to determine how these levels change after delivery. Twenty preeclamptic and 25 normotensive women at term consented to have blood taken pre- and post-delivery. Ten preeclamptic, 10 gestational hypertensive, and 28 normotensive women had blood collected respectively at 12, 20, and 30 weeks gestation and predelivery. Serum was extracted from all samples, and VEGF concentrations were determined by radioimmunoassay. Predelivery, the median serum VEGF concentration in the preeclamptic group was 51.7 ng/mL, and in the control group the concentration was 13.9 ng/mL (P<0.0001). Serum VEGF concentrations fell within 24 hours of delivery in both groups, which resulted in median values of 3.8 ng/mL and 3.2 ng/mL respectively (P<0.3). At 12 and 20 weeks, there was no significant difference between the serum VEGF concentrations in the 3 groups (P<0.3, 0.052 respectively). At 30 weeks, prior to the onset of clinical PE, the serum VEGF levels in the eventual preeclamptic group were elevated significantly compared with the gestational hypertensive and normotensive groups (P<0.001). Predelivery serum VEGF concentrations were significantly elevated in the preeclamptic group and were similar to those in the first study (P<0.0001). These findings suggest that VEGF may be important in the pathophysiology of PE and has the potential to act as a preclinical marker for the condition.
... As discussed in chapter 1, women with pre-eclampsia have excess production of sFlt-1 that binds VEGF in the circulation and is thought to prevent its membrane-bound vasodilatory activity (4,60,61). In women with preeclampsia sFlt-1 levels are increased (60,61,78), however there have been mixed findings when measuring VEGF levels in normotensive pregnancy and pre-eclampsia (2,61,(262)(263)(264). Interestingly, it has been reported that repeated application of remote IPC over at least 4 weeks increases plasma levels of VEGF (192,193). ...
... In my study, baseline levels of VEGF were significantly higher in healthy pregnant women when compared to baseline VEGF levels in women with preeclampsia (table 6.2). However, as previously mentioned there have been mixed findings when measuring VEGF levels in normotensive pregnancy and pre-eclampsia (2,61,(262)(263)(264). One study, with similar findings to my study but with a larger number of participants, found that VEGF levels were lower in the serum of women who had pre-eclampsia, compared to normotensive pregnant women, when samples were taken at 37 to 41 weeks gestation (61). ...
... This study also found that for samples taken at 21 to 32 weeks gestation, the VEGF levels were lower in a group of women who developed pre-eclampsia within 5 weeks of the specimen being taken (61). However, another of these studies, which had comparable participant numbers to my study, found that prior to the onset of pre-eclampsia, serum VEGF levels were significantly elevated in the group of pregnant women who later went on to develop preeclampsia compared to normotensive pregnant women and women with gestational hypertension (264). This study also found that VEGF samples were significantly elevated in women with pre-eclampsia who had samples taken 24-hours prior to delivery, compared to normotensive pregnant women and women with gestational hypertension (264). ...
Pre-eclampsia is a syndrome of pregnancy, classically defined by the gestational-onset of hypertension and proteinuria. Pre-eclampsia complicates 4% of first-time pregnancies and contributes to maternal and neonatal morbidity and mortality globally. Women with pre-eclampsia have reduced utero-placental blood flow, compromising placental and fetal growth. This triggers maternal endothelial dysfunction and variable organ dysfunction. Outside pregnancy, repeated episodes of transient organ ischaemia, (ischaemic pre-conditioning: IPC) has improved endothelial function and blood flow to remote organs. IPC has not previously been tested in pregnancy. The main hypothesis is that local IPC improves endothelial function in women with established pre-eclampsia, as measured by brachial artery flow-mediated dilatation (FMD). To investigate how IPC may improve endothelial function, levels of vasoactive factors were assayed. I first investigated healthy non-pregnant women of childbearing age (n=24) to determine the time-interval following IPC that gave the greatest improvement in FMD. Having identified a 24-hour study interval, I carried out FMD before and after IPC in healthy normotensive pregnant women (n=42), women at risk of pre-eclampsia (n=20), and women with established pre-eclampsia (n=10). The results demonstrate that IPC significantly improves endothelial function in women with pre-eclampsia and at risk of pre-eclampsia (3.5% to 5.8% and 7.6% to 8.9% respectively, vs 10.3% to 10.5% in healthy women). IPC also shortened the time to reach peak FMD in healthy pregnant women. As expected, women with pre-eclampsia had higher sFlt-1 and lower PlGF levels, and higher sFlt1:PlGF ratios. Following IPC, there were no changes to these levels, nor consistent changes to levels of SDF-1, DPP-4 or VEGF. In conclusion, my results suggest that local IPC improves endothelial function in women with pre-eclampsia and at risk of pre-eclampsia. The relative simplicity and cost-effectiveness of IPC, make it an attractive intervention worthy of further investigation as a prophylaxis or treatment of pre-eclampsia.
... The individuals in the AIP group did not have significantly different BMIs compared with the control group (Table 1). A slight increase in serum VEGF levels during the course of pregnancy has been shown in other studies [46][47][48]. To control for this effect (which is much stronger in preeclamptic pregnancies), the groups were matched for gestational age at blood retrieval. ...
... As most of the blood samples were drawn during third trimester, the usefulness of determining these biomarkers earlier in pregnancy-which would be the prerequisite for a useful biomarker-still must be investigated. Two studies exist (N = 48; N = 70), which have documented maternal serum VEGF at 3 or 5 time points during pregnancy in women with preeclampsia, gestational hypertension, or normotension [47,48]. Due to this limited evidence, no normal values or standard curves according to gestational age are available for VEGF and the measured biomarker levels cannot yet be expressed as multiples of the median. ...
... Due to this limited evidence, no normal values or standard curves according to gestational age are available for VEGF and the measured biomarker levels cannot yet be expressed as multiples of the median. However, VEGF levels appear to be very stable throughout normotensive pregnancies [47,48]. However, the study shows that the biomarker levels are still altered in third trimester. ...
The aim of this study was to test if maternal serum vascular endothelial growth factor (VEGF) or N-terminal pro B-type natriuretic peptide (NT-proBNP) predicts abnormally invasive placenta (AIP) better. Secondary objective was to test whether the serum levels of VEGF and NT-proBNP can predict the degree of invasion. In a multicenter case–control study design, gestational age-matched serum samples from pregnant women with AIP (n = 44) and uncomplicated pregnancies (n = 55) who had been enrolled at Charité – Universitätsmedizin Berlin, Germany and Centre Hospitalier Régional de la Citadelle in Liège, Belgium were analyzed. Maternal blood serum VEGF and NT-proBNP levels were immunoassayed from samples taken immediately before delivery (GA median: 35 weeks). Biomarker levels were compared between AIP and control group. The correlation of biomarker levels with the clinical AIP degree was assessed. The predictive biomarker ability was characterized through a multivariate regression model and receiver operating characteristic curves. Women with AIP had significantly lower maternal serum VEGF levels (AIP mean 285 pg/ml, 95% CI 248–322, vs. control: 391 pg/ml, 95% CI 356–426, p < 0.01) and higher NT-proBNP levels (AIP median 329 pg/ml, IQR 287–385, vs. control 295 pg/ml, IQR 273–356, p = 0.03). Maternal serum VEGF levels were able to predict AIP better (AUC = 0.729, 0.622–0.836, p < 0.001; VEGF + number of previous cesarean deliveries: AUC = 0.915, 0.853–0.977, p < 0.001). Maternal serum VEGF levels correlated inversely with the clinical AIP degree (r = − 0.32, p < 0.01). In short, maternal serum VEGF, more than NT-proBNP, can help in predicting AIP and hints at the degree of invasion.
... In women with preeclampsia increased levels of VEGF were reported by several authors, 15,16,17 whereas other authors have reported decreased levels, 18,8 a discrepancy which probably has to do with the methodology. 8 Studies conducted by various authors in women with PE have shown increased systemic VEGF levels 15,16,17 and reports of decreased levels by other authors, 18,8 often leading to discrepancy which might be due to procedures followed. ...
... In women with preeclampsia increased levels of VEGF were reported by several authors, 15,16,17 whereas other authors have reported decreased levels, 18,8 a discrepancy which probably has to do with the methodology. 8 Studies conducted by various authors in women with PE have shown increased systemic VEGF levels 15,16,17 and reports of decreased levels by other authors, 18,8 often leading to discrepancy which might be due to procedures followed. 8 Evidences shows that antagonism in VEGF may have a role in hypertension and proteinuria. ...
... 22,23 The role of VEGF in preeclampsia has received considerable importance. Studies conducted by various authors in women with PE have shown increased systemic VEGF levels, 15,16,17 and reports of decreased levels by other authors, 18,8 often leading to discrepancy which might be due to procedures followed. During pregnancy, unlike in the non-pregnant state, most VEGF is bound to circulating sFlt1 due to very high levels of the latter. ...
... In contrast, vascular endothelial growth factor (VEGF), an anti-fibrotic factor is much less consistent in study findings. Some studies found lowering of VEGF levels in PE [45], while other studies found no differences [46,47] or observed even elevated VEGF levels [47]. This may be due to the effect of differences in inclusion criteria, gestational age or postpartum intervals. ...
... In contrast, vascular endothelial growth factor (VEGF), an anti-fibrotic factor is much less consistent in study findings. Some studies found lowering of VEGF levels in PE [45], while other studies found no differences [46,47] or observed even elevated VEGF levels [47]. This may be due to the effect of differences in inclusion criteria, gestational age or postpartum intervals. ...
Preeclampsia (PE) is strongly associated with heart failure (HF) later in life. The aberrant cardiac remodelling is likely initiated or amplified during preeclamptic pregnancy. Aberrant remodelling often persists after delivery and is known to relate strongly to cardiac fibrosis. This review provides an overview of pro- and anti- fibrotic circulating effector molecules that are involved in cardiac fibrosis and their association with PE.
PE complicated pregnancies show increased ANG-II sensitivity and elevated levels of the pro-fibrotic factors IL-6, TNF-α, TGs and FFAs compared to uncomplicated pregnancies. In the postpartum period, PE pregnancies compared to uncomplicated pregnancies have increased ANG-II sensitivity, elevated levels of the pro-fibrotic factors IL-6, TNF-α, LDL cholesterol and leptin, as well as decreased levels of the anti-fibrotic factor adiponectin.
The review revealed several profibrotic molecules that associate to cardiac fibrosis during and after PE. The role that these fibrotic factors have on the heart during and after PE may improve the understanding of the link between PE and HF. Furthermore they may provide insight into the pathways in which the relation between both diseases can be understood as potential mechanisms which interfere in the process of cardiovascular disease (CVD). Unravelling the molecular mechanism and pathways involved might bring the diagnostic and therapeutic abilities of those factors a step closer.
... VEGF-A, VEGF-B, and PlGF activate tyrosine kinase receptor Flt-1 [VEGF receptor (VEGFR)-1], and VEGF-A activates VEGFR-2 (Flk-1 or KDR) to promote placental vascularization (35). However, measurements of circulating VEGF showed decreases (68), no change (54,55), and even increases in women with PE (9,34,89). PlGF has 1/10th of the affinity of VEGF for VEGFR-1, but its levels are~40 times higher than VEGF during normal pregnancy (40) and are consistently decreased in PE (8,89). On the other hand, soluble fms-like tyrosine kinase-1 (sFlt-1 or sVEGFR-1) is an antiangiogenic alternatively spliced variant of VEGFR-1 that lacks both the transmembrane and cytoplasmic domains and binds circulating VEGF and PlGF and prevents them from activating their cell surface VEGFR-1 (43). ...
... A previous study infused recombinant VEGF at 90 or 180 g·kg Ϫ1 · day Ϫ1 to restore the angiogenic balance and showed that it lowered BP and improved renal function in RUPP rats (30). We selected PlGF over VEGF because most studies have shown decreased PlGF levels in PE (8,53,89), whereas measurements of VEGF have not been consistent, with studies showing decreased (68), no change (54,55), or even increased levels (9,34,89). Also, PlGF is specific for VEGFR-1 and its soluble form sFlt-1, whereas VEGF also binds to VEGFR-2 and could increase vascular permeability and edema (49) and promote cancer (77). VEGF levels are also controlled at the maternal-fetal interface, partly through feedback modulation of sFlt-1, to prevent damage to the placenta or fetus by excess VEGF (21), and dysregulation of this feedback mechanism could complicate the measurement of angiogenic factors. ...
Preeclampsia is a complication of pregnancy manifested as maternal hypertension (HTN-Preg) and fetal growth restriction (IUGR), with unclear mechanism. Placental ischemia increases antiangiogenic soluble fms-like tyrosine-kinase-1 (sFlt-1) relative to angiogenic placental-growth-factor (PlGF); however, the molecular targets are unclear. To test the hypothesis that placental ischemia-induced changes in sFlt-1 and PlGF target vascular and uteroplacental matrix metalloproteinases (MMPs), we tested if raising sFlt-1/PlGF ratio by infusing sFlt-1 (10 µg/kg/day) in pregnant (Preg) rats increases blood pressure (BP) and alters MMPs, and if correcting sFlt-1/PlGF by infusing PlGF (20 µg/kg/day) in Preg rats with reduced uterine perfusion pressure (RUPP) improves BP and reverses the changes in MMPs. On gestational day 19, BP was higher, and the litter size and uterine, placenta, and pup weight were less in Preg+sFlt-1 and RUPP than Preg rats, and restored in RUPP+PlGF vs RUPP rats. Gelatin and casein zymography and Western blots revealed decreases in MMP-2 and MMP-9 and increases in MMP-1 and MMP-7 in aorta, uterine artery, uterus and placenta of Preg+sFlt-1 and RUPP vs Preg rats, that were reversed in RUPP+PlGF vs RUPP rats. Collagen-I and IV were more abundant in Preg+sFlt-1 and RUPP vs Preg rats, and were reversed in RUPP+PlGF vs RUPP rats. Thus PlGF reverses decreased vascular and uteroplacental MMP-2 and MMP-9, and increased MMP-1, MMP-7 and collagen-I and IV induced by placental ischemia and sFlt-1 in HTN-Preg. Angiogenic factors and MMP modulators could rectify changes in MMPs and collagen, restore vascular and uteroplacental remodeling, and improve HTN and IUGR in preeclampsia.
... A.Hunter и соавт. сообщили о значительном увеличении концентрации сосудисто-эндотелиального фактора роста (СЭФР) в сыворотке крови за несколько недель до клинических проявлений ПЭ [39]. С.Lam и соавт. ...
... Ежедневное применение 1,5-2,0 г кальция (объем исследования 15730 беременных группы риска ПЭ) показал снижение риска развития ПЭ только у пациенток с нутриентным дефицитом. Применение витамина D в дозе 800-1200 мкг в сутки (общее число обследованных 1023 пациентки) и антиоксидантов -витаминов Е и С (число обследованных 22359 пациенток) достоверно не влияет на частоту возникновения ПЭ, поэтому они не рекомендованы ВОЗ для профилактики ПЭ [21,39]. С начала 90-х годов ХХ века проводились исследования по применению антиагрегантов с целью профилактики. ...
Pre-eclampsia/eclampsia is one of the most serious pregnancy complications in modern obstetrics. The article presents the historical data about the study of pre-eclampsia and eclampsia since the 4th century BC. The evolution of terminology is presented. According to the development of medical science there appeared a new theory of the etiology and the conception of pathogenesis developed. It shows the contribution of Russian scientists to improve methods of diagnosis, treatment and prevention of this complication of pregnancy. The achievements of modern obstetric science allow to predict pre-eclampsia from early pregnancy. Despite long history of studying, many aspects of this problem still remain unresolved.
... Furthermore, this polymorphism alone may not be able to explain the prevalence of preeclampsia in certain ethnic groups considering its being a complex polygenic disease. Compared with normotensive women, preeclamptic women have increased VEGF levels (49)(50)(51)(52), while the T allele of VEGF-A rs3025039 is associated with lower plasma VEGF compared with the C allele (38). Thus, our finding that the T allele associates with the maintenance of normal pregnancy and may confer a protective effect against the development of preeclampsia is consistent with the concept of having the T allele and low VEGF levels among women with normal, uncomplicated pregnancies. ...
... Thus, our finding that the T allele associates with the maintenance of normal pregnancy and may confer a protective effect against the development of preeclampsia is consistent with the concept of having the T allele and low VEGF levels among women with normal, uncomplicated pregnancies. VEGF level has been reported to increase in patients with preeclampsia (49)(50)(51)(52) and some of the clinical characteristics of preeclampsia, including placental hypercoagulation and hypertension, have been induced in pregnant mice upon the administration of exogenous VEGF (53). Conversely, the levels of sFlt-1, an endogenous antagonist of VEGF, have been shown to increase in preeclampsia way before the onset of maternal symptoms (12). ...
The vascular endothelial growth factor (VEGF) family is important for establishing normal pregnancy, and related single nucleotide polymorphisms (SNPs) are implicated in abnormal placentation and preeclampsia. We evaluated the association between preeclampsia and several VEGF SNPs among Filipinos, an ethnically distinct group with high prevalence of preeclampsia. The genotypes and allelic variants were determined in a case-control study (191 controls and 165 preeclampsia patients) through SNP analysis of VEGF-A (rs2010963, rs3025039) and VEGF-C (rs7664413) and their corresponding receptors VEGFR1 (rs722503, rs12584067, rs7335588) and VEGFR3 (rs307826) from venous blood DNA. VEGF-A rs3025039 C allele has been shown to associate with preeclampsia (odds ratio of 1.648 (1.03-2.62)), while the T allele bestowed an additive effect for the maintenance of normal, uncomplicated pregnancy and against the development of preeclampsia (odds ratio of 0.62 (0.39-0.98)). VEGFR1 rs722503 is associated with preeclampsia occurring at or after the age of 40 years. The results showed that genetic variability of VEGF-A and VEGFR1 are important in the etiology of preeclampsia among Filipinos.
... VEGF-A, VEGF-B, and PlGF bind to tyrosine kinase receptor Flt-1 (VEGFR-1), and VEGF-A binds to VEGFR-2 (Flk-1 or KDR) to promote development of placental vasculature (29). Measurements of circulating levels of VEGF in PE have not been consistent, with studies showing decreased (56), unchanged (46,48), or even increased levels in PE (7,26,72). In comparison, PlGF has only 1/10th the affinity for VEGFR-1 compared with VEGF, but its levels are ϳ40 times higher than VEGF during normal pregnancy (33). ...
... A previous elegant study used recombinant VEGF infusion at 90 or 180 g·kg Ϫ1 ·day Ϫ1 to restore angiogenic balance and showed that it lowered BP and improved renal function in rats with placental ischemia-induced HTN (21). We used PlGF instead of VEGF because of the following: 1) Most studies show decreased PlGF levels in PE (6,45,72), while measurements of VEGF have not been consistent with studies showing decreased (56), not changed (46,48), or even increased levels in PE (7,26,72). 2) In PE, there is an increase in circulating sFlt-1 that binds to VEGF; thus total (bound and unbound) VEGF levels could be elevated or not changed in most forms of PE and PE-like models. On the other hand, the angiogenic imbalance is induced because the free, unbound form of VEGF is decreased, due to the sequestering, neutralizing effect of sFlt-1 (5). 3) VEGF may stimulate sFlt-1 production in the placenta through an action on VEGFR-2 (15). ...
Preeclampsia (PE) is a pregnancy-related hypertensive disorder (HTN-Preg) with unclear mechanism. Imbalance between anti-angiogenic soluble fms-like tyrosine kinase-1 (sFlt-1) and angiogenic placental growth factor (PlGF) has been observed in PE, but the vascular targets and signaling pathways involved are unclear. We tested if inducing sFlt-1/PlGF imbalance by infusing sFlt-1 (10 µg/kg/day) in pregnant (Preg) rats increases BP and vascular reactivity; and if restoring sFlt-1/PlGF balance by infusing PIGF (20 µg/kg/day) in a rat model of reduced uterine perfusion pressure (RUPP) improves BP and vascular function. On gestation day 19, BP was in Preg+sFlt-1 and RUPP>Preg and in RUPP+PlGF<RUPP. Plasma sFlt-1/PlGF ratio was increased in Preg+sFlt-1 and RUPP, and was reduced in RUPP+PlGF rats. In endothelium-intact aorta, carotid, mesenteric and renal artery, pheylephrine (Phe) and high KCl-induced contraction was in Preg+sFlt-1 and RUPP>Preg and RUPP+PlGF. The differences in vascular reactivity between groups were less apparent in vessels treated with NOS inhibitor L-NAME or guanylate cyclase inhibitor ODQ or endothelium-denuded, suggesting changes in endothelial NO-cGMP. Acetylcholine (ACh)-induced relaxation was in Preg+sFlt-1 and RUPP<Preg and RUPP+PlGF, and was blocked by L-NAME, ODQ or endothelium-removal. Aortic total eNOS and phospho-eNOS were in Preg+sFlt-1 and RUPP<Preg and RUPP+PlGF. ACh-induced vascular nitrate/nitrite production was in Preg+sFlt-1 and RUPP<Preg and RUPP+PlGF. Vascular relaxation to sodium nitroprusside was not different among groups. Thus, a tilt in angiogenic/anti-angiogenic balance towards sFlt-1 is associated with decreased vascular relaxation via NO-cGMP and increased vasoconstriction and BP. Restoring angiogenic/anti-angiogenic balance using PlGF enhances vascular relaxation and decreases vasoconstriction and BP in HTN-Preg.
... Además, diferentes investigaciones no han tomado en cuenta la interacción con el sVEGFR-1 o las interacciones entre el VEGF y el PIGF. Se han encontrado concentraciones elevadas de VEGF en el suero y plasma de algunas preeclámpticas (103,104) pero no en otras (105,106). En los estudios donde las concentraciones están elevadas, se correlacionan con la severidad de la hipertensión (107). ...
... En los estudios donde las concentraciones están elevadas, se correlacionan con la severidad de la hipertensión (107). Más aún, las concentraciones pueden ser anormalmente altas en la mitad del embarazo (108) pero no antes (103). ...
... Most studies agree that in pathological conditions, such as pregnancies complicated by preeclampsia or type 2 diabetes mellitus, low expression of VEGF and high expression of the VEGF-R are observed [10]. However, even though a substantial number of studies find increased total VEGF levels in preeclampsia, which may also be related to preeclampsia severity, others report them as reduced or at the same levels as healthy women [11][12][13][14][15][16]. A recent study showed decreased levels of VEGF and increased levels of sFlt-1, the endogenous antagonist of VEGF, in the serum of women with preeclampsia relative to women with gestational hypertension, which were also related to the severity of preeclampsia [17]. ...
The increased prevalence of obesity worldwide has been implicated in the alarming rise of the incidence of gestational diabetes and preeclampsia, which are both considered threatening conditions for both mother and fetus. We studied gene polymorphisms of the proinflammatory cytokine Interleukin 6 (IL-6) and the gene expression levels of VEGF (vascular endothelial growth factor) and VEGF-R (endothelial growth factor receptor), all known to be involved in pregnancy complications, aiming to identify possible predisposing risk factors in pregnancies with obesity. The G allele of IL-6 was found to correspond with an increased risk for gestational diabetes and preeclampsia occurrence. Furthermore, in obese pregnant mothers with either gestational diabetes or pre-existing type 2 diabetes and those who developed preeclampsia, it was confirmed that gene expression levels of VEGF were reduced while they were increased for VEGF receptors. We conclude that the genetic profile of an obese pregnant woman shares a common background with that of a patient with pre-existing type 2 diabetes mellitus, and therefore predisposes them to complications in pregnancy.
... As a result of decreased VEGF signalling, impairments in endothelial cell functionality occur [21]. The prenatal serum VEGF level in pregnant women with preeclampsia was reported to be 51.7 ng/mL, while it was 13.9 ng/mL in the control group [22]. On the other hand, PlGF, a member of the VEGF protein family, sharing about 53% similarity with VEGF [23], is critical to placental angiogenesis and early trophoblast growth. ...
Preeclampsia, a potentially life-threatening condition for both mother and baby, is characterized by hypertension and potential organ damage. Early diagnosis is crucial to mitigate its adverse health effects. While traditional diagnostic methods focus on late-manifesting symptoms like hypertension and proteinuria, there is an increasing emphasis on molecular diagnostic approaches for timely detection and intervention. This study explores the design and evaluation of aptamers for specific detection of the Vascular Endothelial Growth Factor (VEGF) and Placental Growth Factor (PlGF) as biomarkers for preeclampsia, given their roles in angiogenic imbalances associated with the condition and their impact on placental development. Leveraging aptamers as an alternative to antibodies, we designed specific sequences for VEGF and PlGF, delving deep into their binding dynamics and interaction patterns. Aptamers were designed by combining nucleotides with a high affinity towards the receptors, and the affinity of these aptamers towards the receptors was evaluated using in-silico and in-vitro techniques. Based on in-vitro validations, we identified specific aptamers showing nano-molar level affinities towards VEGF and PlGF. These aptamer designs could help develop new aptasensor-based, cost-effective point-of-care technologies with high sensitivity and specificity.
... Boundary conditions for the model are defined at the uterine artery. Mean uterine artery flow and pressure typical of each gestational stage is defined from the literature (17,44,45) (APPENDIX Table A1) and flow division through each level of the vascular tree network can then be estimated. Finally, shear stress, s, on the endothelial cells in the radial arteries is defined as ...
Fetal growth throughout pregnancy relies on delivery of an increasing volume of maternal blood to the placenta. To facilitate this, the uterine vascular network adapts structurally and functionally, resulting in wider blood vessels with decreased flow-mediated reactivity. Impaired remodeling of the rate-limiting uterine radial arteries has been associated with fetal growth restriction. However, the mechanisms underlying normal or pathological radial artery remodeling are poorly understood. Here, we used pressure myography to determine the roles of haemodynamic (resistance, flow rate, shear stress) and paracrine (β-estradiol, progesterone, placental growth factor (PlGF), vascular endothelial growth factor) factors on rat radial artery reactivity. We show that β-estradiol, progesterone, and PlGF attenuate flow-mediated constriction of radial arteries from non-pregnant rats, allowing them to withstand higher flow rates in a similar manner to pregnant vessels. This effect was partly mediated by nitric oxide (NO) production. To better understand how the combination of paracrine factors and shear stress may impact human radial artery remodeling in the first half of gestation, computational models of uterine haemodynamics, incorporating physiological parameters for trophoblast plugging and spiral artery remodeling, were used to predict shear stress in the upstream radial arteries across the first half of pregnancy. Human microvascular endothelial cells subjected to these predicted shear stresses demonstrated higher NO production when paracrine factors were added. This suggests that synergistic effects of paracrine and haemodynamic factors induce uterine vascular remodeling, and that alterations in this balance could impair radial artery adaptation, limiting blood flow to the placenta and negatively impacting fetal growth.
... Also, as it is known that the VEGF level can be affected by the BMI of the studied participants, we have matched this item between studied cases and controls. Hunter et al., 2000, 19 Bosio et al., 2001 20 and Palm et al., 2011 21 report a minimal increase in serum VEGF level during pregnancy course. For this reason, we also matched our studied groups for gestational age. ...
This study planned to compare the predictive ability of maternal urinary vascular endothelial growth factor (VEGF) versus N-terminal pro B-type natriuretic peptide (NT-pro BNP) for prediction of placenta accreta spectrum (PAS). This was a prospective case-control study carried out in a tertiary university hospital. It included pregnant women between 37-39 weeks. The study included 50 pregnant women classified in two groups. Group (Ι, n=25) were pregnant women with PAS, and group (II, n=25) women with uncomplicated pregnancies, as controls. Urine samples were collected, and quantitative analyses of VEGF and NT-pro BNP were performed by ELISA. VEGF was assessed with a cut point of 215.6 pg/ml and NT-pro BNP with a cut point of 182.2 pg/ml to predict the condition of PAS. Both biomarkers were good predictors of PAS with the area under the ROC curve (AUC) equal to (0.871 and 0.904), respectively. However, maternal urinary VEGF levels could predict PAS better than NT-pro BNP (OR=9.967, 95%CI 2.032-48.879, p=0.005) versus (OR=8.066, 95% CI 1.520 - 42.811, p=0.014) in NT-pro BNP. In conclusion, third trimester urinary levels of both VEGF and NT-pro BNP appear to be s crucially good predictors for PAS. However, VEGF is superior to NT-pro BNP in predicting women with PAS. These biomarkers present promising candidates as they can help to detect patients at high probability of PAS. They can be assessed by non-invasive, simple, and low-cost procedures.
... For instance, eNOS is responsible for the production of the vasodilator nitric oxide (NO), whose concentrations are decreased in preeclampsia [22,23]. Additionally, VEGFA a pro-survival endothelial cell factor responsive to hypoxia-mediated angiogenesis, vasculogenesis, spiral arteries remodeling, and trophoblast survival [14] is impaired in preeclampsia with reports showing either increased [24] or decreased [25] levels. In addition, VEGFA functions are exerted through the activation of a tyrosine kinase receptors family, including VEGFR-1, VEGFR-2, and VEGFR-3 [26]. ...
Introduction:
Preeclampsia is a leading cause of maternal and fetal morbidity in low- and middle-income countries, including those in Latin America. Placental vascular alterations are crucial in the pathophysiology of preeclampsia and few studies have evaluated nucleotide variations on genes associated with vascular regulation in the human placenta. This study aimed to evaluate whether placental nucleotide variations on eNOS, VEGFA, and FLT-1 genes are more frequently associated with preeclampsia in the Latin American population.
Methods:
This case-control study included placental tissue from 88 controls and 82 cases that were genotyped through Taqman probes for eNOS, VEGFA, and FLT-1 genes. The intergroup comparisons were analyzed with the Mann-Whitney U test. Genotype and allele frequencies were compared by the X2 test. The association between the nucleotide variants with preeclampsia was evaluated through logistic regression analysis.
Results:
A significant association was observed for VEGFA SNV rs2010963 (OR 1.95; CI 95% 1.13-3.37), after adjusting for population substructure. The allele combination T, G, G, C, C, C (rs2070744, rs1799983, rs2010963, rs3025039, rs699947 and rs4769613 respectively), showed a negative association with preeclampsia (OR 0.08; CI 95% 0.01-0.93).
Discussion:
Placental SNV rs2010963 in the VEGFA gene was a risk factor for preeclampsia, while the allele combination T, G, G, C, C, C may represent potential protective factors for preeclampsia within Latin American women.
... HTR8 cells were cultured under hypoxia and normal. Angiogenic capacity was detected by endovascular tube formation assay angiogenesis [32][33][34][35]. Conversely, other studies have reported reduced expression levels of VEGF throughout the body [36][37][38]. ...
Abstract Background Preeclampsia (PE) is a complication of pregnancy that causes long-term adverse outcomes for the mother and fetus and may even lead to death. Oxidative stress caused by the imbalance of oxidants and antioxidants in the placenta has been considered as one of the key mechanisms of preeclampsia (together with inflammation, etc.), in which the placental mitochondria play an important role. The expression of hypoxia-inducible factor-1 (HIF-1α) and vascular endothelial growth factor (VEGF) is known to be increased in patients with PE. Mitochondrial ferritin (FtMt) is known to protect the mitochondria from oxidative stress, although its specific role in PE remains unclear. Methods We used qRT-PCR and western blotting to detect the expression levels of FtMt, HIF-1α, and VEGF in placental tissues from patients with PE. Human chorionic trophoblast cells were also administered with hypoxia treatment, followed by the detection of cell proliferation, invasion and angiogenic capacity by CCK8, Transwell, and endothelial cell angiogenesis assays; we also detected the expression of HIF-1α and VEGF in these cells. Finally, overexpression or inhibitory FtMt lentiviral vectors, along with negative control vectors, were constructed and transfected into hypoxia-treated human chorionic trophoblast cells; this was followed by analyses of cell function. Results The expression levels of FtMt, HIF-1α and VEGF in the PE group were higher than those in the control group (P
... In early pregnancy, the VEGF protein is expressed in cytotrophoblasts at the implantation site and the expression of VEGF protein continues until term [8]. The decline in the post -delivery expression of VEGF suggests that placenta is the source of VEGF [9]. In previous reports VEGF A was referred to as VEGF [10]. ...
Objective: The study was undertaken to compare the chorionic villi protein expressions of vascular endothelial growth factor (VEGF) 165 , VEGF 165 b and matrix metalloproteinase (MMP)-9 in preeclampsia and in normotensive pregnancies. Methods: We studied 77 placentas, 53 from term deliveries of healthy women with uncomplicated pregnancies and 24 from women with preeclampsia. Protein expressions were determined by enzyme linked immunoassays (ELISA) using commercially available kits. The capture antibody for each of the ELISA kits was monoclonal antibody to the respective three human proteins. Results: Race/ethnicity in the study was self-reported and the distribution showed that 65 % of the study population was of Hispanic and 35 % was of African American descent. Mann Whitney U test results show that chorionic villi VEGF 165 b protein expression differed significantly between normal pregnancies and preeclampsia (p = 0.0001). Spearman's rank correlation showed a significant positive correlation between the two isoforms of VEGF 165 (rho = +0.365, p = 0.007) in the third trimester of normal pregnancy, suggesting a synergistic action between the two proteins. In preeclampsia, this apparent synergy between the two VEGF proteins was not seen. In normal term delivery group, Spearman' s rank correlation showed VEGF 165 b protein expression was significantly and negatively correlated with MMP-9 (rho =-0.271, p = 0.049). In preeclampsia this correlation was not seen. In the normotensive group, VEGF 165 b protein expression in chorionic villi were found to be higher in women carrying a female fetus (p = 0.035); and placental weight in women carrying female fetuses was significantly higher (p = 0.032) as well. All studied variables were comparable between African American and Hispanic population except for VEGF 165 b which was significantly higher among African American population (p = 0.022). The systolic and diastolic blood pressure among African American population were also significantly higher (p = 0.016, 0.001, respectively). Conclusions: The study underscores an important association between VEGF 165 b isoform and MMP-9 in normotensive pregnancy. Our findings strengthen our hypothesis that VEGF 165 b may play a significant role in normal human pregnancy. Our study corroborates previous reports that found African Americans to be at a higher risk for preeclampsia. In preeclampsia, vasoconstriction may be responsible for the elevated expression of VEGF 165 b protein, as tissue ischemia has been reported to stimulate VEGF 165 b levels. In the absence of a suitable animal model to study preeclampsia, more correlative data may contribute to a better understanding of the pathophysiology of preeclampsia in the future.
... Hence, the development of preeclampsia caused by decreased uteroplacental blood flow leads to changes in the expression of pro-angiogenic and anti-angiogenic mediators, and the main source of their production is syncytiotrophoblast. Increased levels of serum VEGF and soluble form of sFlt-1 promote the development of preeclampsia symptoms, in particular, BP elevation [4,9]. Our immunohistochemical study demonstrated increased level of VEGF expression mainly in syncytiotrophoblast of the terminal villi in parturient women with moderate COVID-19 to a greater extent than in women with mild disease severity. ...
A comparative morphological study was carried out to analyze the number of syncytial knots and VEGF expression in placental villi in parturient women with COVID-19 categorized by the disease severity. The number of syncytial knots was assessed on specimens stained with hematoxylin and eosin. VEGF expression was determined by immunohistochemical analysis in syncytiotrophoblast and villous endothelial cells. Morphological study of the placenta tissue of parturient women with COVID-19 showed increased numbers of syncytial knots in the villi, indicating the development of preplacental hypoxia. High VEGF expression in syncytiotrophoblast and vascular endotheliocytes reflects a stereotyped response to hypoxia and can underlie the development of a preeclampsia-like syndrome. The number of syncytial knots and VEGF expression in placental villi in parturient women with COVID-19 depended on the disease severity.
... The question remains about the origin of the secreted VEGF during pregnancy. A longitudinal study showed that serum concentrations of VEGF in normotensive (NT) pregnant women increased regularly during the pregnancy [22]. The concentrations at delivery were ~ 3 times higher than the concentrations measured at 12 weeks' gestation. ...
Vascular endothelial growth factor A (VEGF-A) is one of the main growth factors involved in placental vasculogenesis and angiogenesis, but its placental expression is still ambiguous. During in vitro cultures of primary term cytotrophoblasts, VEGF could not be detected in the supernatants by enzyme-linked immunosorbent assays (ELISA). One hypothesis is that VEGF is immediately and completely bound to its soluble receptor after secretion, and cannot be recognized by the antibodies used in the commercial ELISA kits. We decided to verify this hypothesis by measuring VEGF-A expression during in vitro cultures of primary term cytotrophoblasts. Term cytotrophoblasts were cultured under 21% and 2.5% O2 for 4 days. VEGF-A transcripts were quantified by real-time polymerase chain reaction. The proteins from cell lysates and concentrated media were separated by polyacrylamide gel electrophoresis (PAGE) under denaturing and reducing conditions, and VEGF-A immunodetected by western blotting. VEGF mRNA expression did not increase during in vitro cell differentiation under 21% O2, but slightly increased under 2.5% O2 only at 24 h. VEGF-A monomer was not detected in the cell lysates and in the concentrated supernatants, while a ~ 42 KDa band corresponding to the precursor L-VEGF was detected in all the cellular extracts. Isolated term villous cytotrophoblasts produce the L-VEGF precursor but they do not secrete VEGF-A even under low-oxygen tension. The question remains about the origin of VEGF in pregnancy but also about the biological role of L-VEGF, which can represent a form of storage for rapid VEGF secretion when needed.
... This is supported in other studies where rises in circulating and urinary levels of PlGF occur from 8 to 12 weeks to maximum by 29-33 weeks [32,69]. In contrast, serum vascular endothelial growth factor (VEGF) levels do not change dramatically throughout the course of normal gestation [70]. But it is important to note that PlGF is thought to promote vasodilation by increasing VEGF signaling because of the ability of PlGF to bind with high affinity to VEGF receptor 1 (VEGFR1) whereas, VEGF binds both VEGFR1 and VEGFR2 [71]. ...
: Proper vascular tone and blood pressure regulation during pregnancy are important for immediate and long-term cardiovascular health of the mother and her offspring. Preeclampsia is clinically defined as new-onset maternal hypertension accompanied by cardiovascular, renal, and/or neural abnormalities presenting in the second half of pregnancy. There is strong evidence to support that preeclampsia is mediated by attenuations in uteroplacental vascular remodeling and increases in vasoconstriction with subsequent placental ischemia/reperfusion-induced release of hypertensive substances into the maternal circulation. These include antiangiogenic and pro-inflammatory factors. There is also evidence implicating increased sympathetic nervous system activity (SNA) in this maternal disorder, but this mostly includes data correlating severity of disease with catecholamine levels and elevated muscle SNA. These measurements have not confirmed a causative role for SNA in the pathogenesis of preeclampsia. Therefore, studies are needed to provide a comprehensive understanding of SNA and its control of vascular function and blood pressure regulation during normal pregnancy in order to set the stage for exploring the mechanisms mediating the exaggerated SNA and signaling during preeclampsia. This review examines the role of SNA in control of uteroplacental vascular tone and blood pressure regulation during normal pregnancy. Furthermore, it is proposed that over-activation of the SNA contributes to altered uteroplacental vascular tone and perfusion leading to placental ischemic events and modulates the systemic vasoconstriction and hypertensive responses to soluble placenta ischemic factors. Recognizing the integrative role and importance of SNA in the pathophysiology of preeclampsia will advance our understanding of this maternal disorder.
... Notably, placental vascular defects and early embryonic death in VEGF-knockout or VEGF-overexpressing mice have been observed in previous studies [10,11]. Increasing evidence has shown that VEGF expression is significantly increased in PE, and importantly, the severity of PE is associated with elevated VEGF expression [12]. Exogenous VEGF121 has been administered to experimental animals in attempts to neutralize excess sFlt-1, revealing that exogenous VEGF121 could alleviate the symptoms of PE [3]. ...
Studies have shown that sFlt-1 overproduction stimulated by excess VEGF of deciduous origin in trophoblasts can cause preeclampsia. However, the mechanism underlying how VEGF regulates sFtl-1 expression in trophoblasts remains unknown. To address this issue, JEG3 and HTR-8/SV neo (HTR8) trophoblast cell lines were used to investigate the signaling pathways involved in the regulation of sFlt-1 production via VEGF overexpression in vitro. JEG3 (VEGF–GFP–JEG3, V-J) and HTR8 (VEGF–GFP–HTR8, V-H) cells overexpressing VEGF165 were established by infecting the JEG3 and HTR8 cell lines with lentivirus expressing VEGF165. Both the mRNA and protein levels of VEGF and sFlt-1 were dramatically up-regulated in the V-J and V-H cells compared to the JEG3 and HTR8 cells, and they were significantly decreased after treatment with an Flt-1 receptor inhibitor (MK-2461), a KDR receptor inhibitor (XL-184), or an Flt-1 and KDR receptor inhibitor (ABT-869). The mRNA levels of sFlt-1, Flt-1, and KDR were increased in V-H cells after treatment, and the VEGF-A mRNA levels were also elevated. The migration and invasion abilities of JEG3 and HTR8 cells were decreased after VEGF overexpression, and this reduction could be reversed with VEGF receptor inhibitor treatment. In addition, after the different treatments, the cell migration rates of V-J cells were significantly increased compared with the control treatment. Taken together, these results indicate that sFlt-1 up-regulation by VEGF may be mediated by the VEGF/Flt-1 and/or VEGF/KDR signaling pathways. However, elucidating which pathway plays this key role requires further investigation.
... The net result of VEGF 165 presence locally in the vasculature at the doses tested would be a negative contribution toward vasodilation. These are, of course, prototypical agonists at prototypical doses used to tease out molecular mechanisms, but it should be noted that neither of these doses are beyond that which can be seen in a physiological or pathophysiological context (7,8,15,19,20,36). Especially when the case of PE is considered, doses of 10 ng/ml total VEGF 165 have been associated with the circulating range in the diseased state (although circulating sFLT-1 consistently reduces systemic bioavailability) and are likely to be easily achieved locally in tissues such as decidua. ...
The role increased vascular endothelial growth factor (VEGF) plays in vascular function during normal vs. preeclamptic pregnancy has been a source of some controversy of late. In this study, we seek to understand how VEGF165 influences vasodilator production via Ca2+ signaling mechanisms in human endothelial cells. We utilize human umbilical vein endothelial cells (HUVEC) as well as intact ex vivo human umbilical vein (HUV Endo) to address direct stimulation of Ca2+ and NO by VEGF165 alone, as well as the effect of VEGF165 on subsequent ATP-stimulated Ca2+ signaling and NO production. We show that VEGF165 stimulates Ca2+ responses in both HUVEC and HUV Endo, which results in a corresponding increase in NO production in HUV Endo. Longer-term VEGF165 pretreatment then inhibits sustained Ca2+ burst responses to ATP in HUVEC and HUV Endo. This is paralleled by a corresponding drop in ATP-stimulated NO production in HUV Endo, likely through inhibition of Cx43 gap-junction function. Thus, although VEGF165 makes a small initial positive impact on vasodilator production via direct stimulation of Ca2+ responses, this is outweighed by the greater subsequent negative impact on Ca2+ bursts and vasodilator production promoted by more potent agonists such as ATP. Overall, elevated levels of VEGF165 associated with preeclampsia could contribute to the endothelial dysfunction by preventing Ca2+ bursts to other agonists including but not limited to ATP.
New & noteworthy:
In this manuscript, we show that VEGF levels associated with preeclampsia are a net negative contributor to potential vasodilator production in both a human ex vivo and in vitro endothelial cell model. Therefore, pharmacological targeting of VEGF-stimulated signaling pathways could be a novel treatment modality for preeclampsia-related hypertension.
... Circulating levels of VEGF vary in PE, with some studies showing an increase in circulating VEGF (Hunter et al., 2000;Tsatsaris et al., 2003;Celik et al., 2013), while other reports show decreased or unchanged levels of serum VEGF (Maynard et al., 2003;Masoura et al., 2014). VEGF production is higher in villous explants from PE than Norm-Preg women (Ahmad and Ahmed, 2004). ...
Preeclampsia is a pregnancy-related disorder characterized by hypertension and could lead to maternal and fetal morbidity and mortality. Although the causative factors and pathophysiological mechanisms are unclear, endothelial dysfunction is a major hallmark of preeclampsia. Clinical tests and experimental research have suggested that generalized endotheliosis in the systemic, renal, cerebral, and hepatic circulation could decrease endothelium-derived vasodilators such as nitric oxide, prostacyclin, and hyperpolarization factor and increase vasoconstrictors such as endothelin-1 and thromboxane A2, leading to increased vasoconstriction, hypertension, and other manifestation of preeclampsia. In search for the upstream mechanisms that could cause endothelial dysfunction, certain genetic, demographic, and environmental risk factors have been suggested to cause abnormal expression of uteroplacental integrins, cytokines, and matrix metalloproteinases, leading to decreased maternal tolerance, apoptosis of invasive trophoblast cells, inadequate spiral arteries remodeling, reduced uterine perfusion pressure (RUPP), and placental ischemia/hypoxia. RUPP may cause imbalance between the antiangiogenic factors soluble fms-like tyrosine kinase-1 and soluble endoglin and the proangiogenic factors vascular endothelial growth factor and placental growth factor, or stimulate the release of other circulating bioactive factors such as inflammatory cytokines, hypoxia-inducible factor-1, reactive oxygen species, and angiotensin AT1 receptor agonistic autoantibodies. These circulating factors could then target endothelial cells and cause generalized endothelial dysfunction. Therapeutic options are currently limited, but understanding the factors involved in endothelial dysfunction could help design new approaches for prediction and management of preeclampsia.
... In the last decade, angiogenic factors such as placental growth factor (PIGF) and soluble fms-like tyrosine kinase (s-FLT-1) were found to be abnormal in the maternal circulation in women who developed PE [6]. Emerging data suggest that serial measurements of circulating angiogenic factors may help predict PE and adverse pregnancy outcomes [3,[7][8][9][10]. However, the data on angiogenic factors in pregnant patients on hemodialysis are limited [9,11]. ...
Background:
Pregnancy in patients on chronic hemodialysis therapy, though unlikely, does happen rarely. Intensive hemodialysis is thought to offer a better survival advantage to the unborn child. Circulating angiogenic factors are helpful for prognostication of pregnant patients with chronic kidney disease who are not on dialysis. Data on their utilization in dialysis patients, however, are limited.
Case presentation:
We report the case of a patient with a history of interstitial nephritis who had a kidney transplant that failed after 8 years due to membranous nephropathy. She was initiated on hemodialysis three sessions per week and conceived after being on dialysis for 6 weeks. She was switched to intensive hemodialysis at 8 weeks of gestation and had a C-section because of hypertension at 35 weeks, with delivery of a healthy girl weighing 2012 g. Serum angiogenic factors (placental growth factor and soluble fms-like tyrosine kinase) were measured at 32, 33, and 34 weeks of gestation and at 1, 2, and 3 weeks postpartum. Serum angiogenic factors were similar to what has been reported for patients with chronic kidney disease and were not consistent with preeclampsia.
Conclusions:
Our case report expands on the literature regarding intensive hemodialysis and angiogenic factor utilization in pregnant dialysis patients. Our case report suggests that starting intensive dialysis early in pregnancy is safe and concentration of angiogenic factors are similar to those reported for patients without kidney disease, except for PIGF levels, which are somewhat higher.
... During pregnancy, reduced free VEGF-A levels are thought to be involved in the onset of preeclampsia, a dangerous pregnancy complication associated with aberrant trophoblasts invasion and vascular remodeling (7,12,13,35). However, while some studies have shown reduced VEGF-A levels in the placenta and serum of preeclamptic patients (36,37), others have shown increased VEGF-A levels (38,39). Interestingly, Maynard et al attributed these discrepancies to the method of VEGF-A detection, such that studies reporting increased levels had measured total (unbound and bound) VEGF-A, whereas those reporting decreased levels had measured free (unbound) VEGF-A. ...
Remodeling of maternal spiral arteries during pregnancy requires a subpopulation of extravillous cytotrophoblasts (EVTs) to differentiate into endovascular EVTs. Activin A, which is abundantly expressed at the maternal-fetal interface, has been shown to promote trophoblast invasion but its role in endovascular differentiation remains unknown. Vascular endothelial growth factor-A (VEGF-A) is well recognized as a key regulator in trophoblast endovascular differentiation. Whether and how activin A might regulate VEGF-A production in human trophoblasts and its relationship to endovascular differentiation has yet to be determined. In the present study, we found that activin A increased VEGF-A production in primary and immortalized (HTR8/SVneo) human EVT cells. In addition, activin A enhanced HTR8/SVneo endothelial-like tube formation, and these effects were attenuated by pre-treatment with siRNA targeting VEGF-A or the VEGF receptor 1/2 inhibitor SU4312. Pre-treatment with the activin/TGF-β type I receptor (ALK4/5/7) inhibitor SB431542 abolished the stimulatory effects of activin A on SMAD2/3 phosphorylation, VEGF-A production and endothelial-like tube formation. Moreover, siRNA-mediated down-regulation of SMAD2, SMAD3 or common SMAD4 abolished the effects of activin A on VEGF-A production and endothelial-like tube formation. In conclusion, activin A may promote human trophoblast cell endothelial-like tube formation by up-regulating VEGF-A production in an SMAD2/3-SMAD4-dependent manner. These findings provide insight into the cellular and molecular events regulated by activin A during human implantation.
... La unión del VEGF total a las proteínas puede causas este problema en todas las pruebas utilizadas, incluyendo la utilizada en esta investigación. Sin embargo, a diferencia de los resultados de informes previos (16,18), Belgore y col. (19) desarrollaron un inmunoensayo con anticuerpos policlonales para el VEGF, el cual puede solucionar los problemas potenciales del ELISA para la detección de la VEGF unida en el embarazo. ...
El objetivo de la investigación fue establecer las concentraciones de factor de crecimiento vascular endotelial (VEGF) total en preeclámpticas y embarazadas normotensas, y relacionar los valores de los hallazgos Doppler de las arterias uterinas con las concentraciones plasmáticas. Se seleccionaron 160 sujetos. Se incluyeron 47 preeclámpticas severas (grupo A), 33 preeclámpticas leves (grupo B) y un grupo control con edades similares a los grupos de estudio de 80 embarazadas sanas (grupo C). Las muestras de sangre para la determinación de VEGF total y las mediciones de los índices de pulsatilidad, índice de resistencia y relación de flujo sistólico / diastólica de las arterias uterinas se realizaron en todas las pacientes antes del parto e inmediatamente después del diagnóstico en las preeclámpticas. Las pacientes del grupo A y B presentaron concentraciones significativamente más elevadas de VEGF total que las embarazadas del grupo C (p < 0,05). Las mediciones del índice de pulsatilidad, índice de resistencia y relación de flujo sístole / diástole de las arterias uterinas mostraron valores significativamente más altos en ambos grupo de las preeclámpticas (p < 0,05). Al correlacionar las concentraciones de VEGF total plasmáticas con los valores de velocimetría Doppler de las arterias uterinas se observó que esta era significativa con los tres parámetros evaluados (p < 0,05). Se concluye que las preeclámpticas presentan concentraciones plasmáticas de VEGF total más altas que las embarazadas normotensas y existe correlación significativa entre las concentraciones plasmáticas y los parámetros de velocimetría Doppler de las arterias uterinas.
The preeclampsia is one of the main causes of maternal mortality. For this reason the issues of early diagnosis, and most importantly individual prediction are currently one of the most urgent aim for practical obstetrics. To the last years many ways has been attempted to creating methods of a personalized approach to the prognosis of the preeclampsia. However, until this day, the problem remains unresolved. This review article presents the most significant methods of individual prognosis of preeclampsia at the preclinical stage based on genetic, immunological and biochemical markers.
Objectives
To determine the levels of angiogenic biomarkers: vascular endothelial growth factor (VEGF), soluble vascular endothelial growth factor receptor 1 (sVEGFR1 or sFlt-1), platelet count, and the VEGF/platelet ratio in preeclampsia.
Methods
Forty-four cases of preeclampsia and 44 controls were recruited.
Results
The serum VEGF, sVEGFR1, and VEGF/platelet ratio were significantly higher and platelet counts lower in preeclampsia in comparison to controls (VEGF: median = 178 vs. 97 pg/mL, p < 0.0001, sVEGFR1: 1634 vs. 627 pg/mL, p < 0.0001, VEGF/platelet ratio: 1.148 vs. 0.417, and platelet count: 178 × 10 ³ /µL vs. 232 × 10 ³ /µL, p = 0.0006). The VEGF and VEGF/platelet ratio showed better diagnostic accuracy for differentiating preeclampsia, with an area under the curve of 97.47% (95% CI: 0.95–1.00) and 89.46% (95% CI: 0.82–0.96), respectively. VEGFA: c.-2055A>C (rs699947) AA genotype exhibited higher serum VEGF levels associated with preeclampsia.
Conclusion
The higher levels of angiogenic biomarkers in preeclampsia, suggest a role in the pathogenesis and potential diagnosis.
Preeclampsia, one of the main hypertensive disorders of pregnancy, is associated with circulating factors released by the ischemic placenta accompanied by systemic endothelial dysfunction. The etiology of preeclampsia remains poorly understood although it is associated with high maternal and fetal mortality and increased cardiovascular disease risk. Most cell model systems used for studying endothelial dysfunction have not taken into account hemodynamic physical factors such as shear-stress forces which may prevent extrapolation of cell data to in vivo settings. We overview the role of hemodynamic forces in modulating endothelial cell function and discuss strategies to reproduce this biological characteristic in vitro to improve our understanding of endothelial dysfunction associated with preeclampsia.
Aim: Antenatal suspicion of placenta accreta spectrum (PAS) currently relies on ultrasonographic findings, color doppler, and MRI, which have rendered it operator and expertise-dependent. No serum markers for PAS have been integrated into clinical practice yet. The aim of this meta-analysis was to identify potential serum markers for PAS by investigating third-trimester serum levels of vascular endothelial growth factor (VEFG), placental growth factor (PIGF), and soluble Fms-like tyrosine kinase-1 (sFlt-1) among PAS-cases and controls.
Methods: PubMed, Scopus, EBSCO, Web of Science, and CNKI databases were systematically searched for relevant articles. Random-effects model was applied to calculate the overall standardized mean difference (SMD) for each marker. Subgroup analysis and meta-regression were performed to assess for potential covariates.
Results: Eight studies involving 366 PAS-cases and 518 controls were included. Third trimester sFlt-1 levels were significantly lower in PAS-cases when compared to controls (SMD = -7.76, 95%CI = -10.42 to -5.10). This was, to a certain extent, consistent among studies though they differed in their extent of significance. Levels of VEGF (SMD = 1.59, 95%CI = -0.07 to 3.25) and PlGF (SMD = -0.49, 95%CI = -1.66 to 0.67) were not significantly different between PAS cases and controls, in which studies demonstrated conflicting
results.
Conclusions: Third trimester sFlt-1 levels may be useful to predict PAS. Nonetheless, further studies are recommended to better understand conflicting results before adopting either VEGF or PlGF.
Key words: biomarkers, meta-analysis, placenta accreta, vascular endothelial growth factor A, vascular endothelial growth factor receptor-1.
Peripartum cardiomyopathy (PPCM) is a potentially fatal form of idiopathic heart failure with variable prevalence across different countries and ethnic groups. The cause of PPCM is unclear, but environmental and genetic factors and pregnancy-associated conditions such as pre-eclampsia can contribute to the development of PPCM. Furthermore, animal studies have shown that impaired vascular and metabolic function might be central to the development of PPCM. A better understanding of the pathogenic mechanisms involved in the development of PPCM is necessary to establish new therapies that can improve the outcomes of patients with PPCM. Pregnancy hormones tightly regulate a plethora of maternal adaptive responses, including haemodynamic, structural and metabolic changes in the cardiovascular system. In patients with PPCM, the peripartum period is associated with profound and rapid hormonal fluctuations that result in a brief period of disrupted cardiovascular (metabolic) homeostasis prone to secondary perturbations. In this Review, we discuss the latest studies on the potential pathophysiological mechanisms of and risk factors for PPCM, with a focus on maternal cardiovascular changes associated with pregnancy. We provide an updated framework to further our understanding of PPCM pathogenesis, which might lead to an improvement in disease definition.
Preeclampsia (PE) is a syndrome related with pregnancy and characterized by hypertension and proteinuria, occurring in approximately 6-8% of pregnancies and accounting for approximately 40% of premature births. This study aimed to investigate the polymorphisms of -634C/G and +936C/T in VEGF gene and their relationship with serum VEGF levels in pregnant women with PE.
In this case-control study, peripheral blood samples were collected from 135 women with PE and 135 normal pregnant women as the control group. DNA was extracted using the phenol-chloroform method. Then, the polymorphisms of VEGF gene were detected by PCR-RFLP method using specific primers. Besides, VEGF concentrations were measured by ELISA method on serum samples and control subjects using ELISA kits.
In this research, maternal age, gestational week, maternal hemoglobin and BMI were significantly correlated with the likelihood of PE, while the occurrence season variable was not effective in PE among the pregnant women. There was no significant difference in the two polymorphisms of -634C/G and +936C/T in VEGF gene between the two groups. Also, the serum VEGF level in PE patients was significantly higher than the normal group (P<0.001).
Despite a significant increase in serum VEGF concentrations in women with PE, it seems that -634C/G and +936C/T polymorphisms of VEGF gene are not related with the onset of PE. Further studies are required to fully understand the risk factors related to preeclampsia syndrome.
Pregnancy, from insemination to parturition, is a highly complex but well-orchestrated process that requires various organs and systems to participate. Immune system and neuroendocrine system are important regulators in healthy pregnancy. Dozens of neuroactive factors have been detected in human placenta, whether they are locally secreted or circulated. Among them, some are vividly studied such as corticotropin-releasing hormone (CRH), human chorionic gonadotropin (hCG), transforming growth factor-β (TGF-β), progesterone and estrogens, while others are relatively lack of research. Though the neuroendocrine-immune interactions are demonstrated in some diseases for decades, the roles of neuroactive factors in immune system and lymphocytes during pregnancy are not fully elucidated. This review aims to provide an interdisciplinary view on how the neuroendocrine system mediate immune system during pregnancy process.
Background:
Preeclampsia has a major impact on renal function as shown by the development of proteinuria and podocyturia. How the systemic, Fms-like tyrosine kinase-1 (sFlt-1)-driven inhibition of vascular endothelial growth factor (VEGF) activity detected in preeclampsia directly affects renal function remains unknown. Aim of the study was to clarify whether a non-canonical, renal centered escape from VEGF inhibition in case of preeclamptic pregnancy might have a direct impact on the renal function.
Methods:
We evaluated plasma and urinary VEGF and placental growth factor (PlGF), plasma sFlt-1 and carbonic anhydrase IX (CAIX), albuminuria and podocyturia in 18 women with uncomplicated pregnancy, 21 with preeclampsia and 18 non pregnant. The three groups were matched for age and the pregnant groups also for gestational age at enrollment.
Results:
Plasma VEGF was reduced in uncomplicated (p = 0.001) and preeclamptic (p = 0.0003) pregnancies when compared to controls. In uncomplicated pregnancy the dysfunction was balanced by an increase (p = 0.009) of plasma PlGF. Increased (p = 0.0001) plasma CAIX in preeclampsia was in line with hypoxia. Preeclampsia resulted in a paradoxical increase (p = 0.0004) of urinary excretion of VEGF. Urinary concentrations of VEGF and podocytes were correlated to each other (r2 = 0.48, p < 0.0005) but also to plasma sFlt-1 (r2 = 0.56, p < 0.0001 and r2 = 0.23, p = 0.03 respectively).
Conclusions:
In case of preeclampsia, the systemic VEGF inhibition brings the kidney, possibly the podocyte, to increase the VEGF synthesis. The mechanisms leading to local VEGF overproduction or the overproduced VEGF itself are reasonably involved in the pathogenesis of podocyturia and, as a consequence, of renal dysfunction in preeclampsia.
Preeclampsia is a multisystem, multiorgan hypertensive disorder of pregnancy responsible for maternal and perinatal morbidity and mortality in low- and middle-income countries. The classic diagnostic features hold less specificity for preeclampsia and its associated adverse outcomes, suggesting a need for specific and reliable biomarkers for the early prediction of preeclampsia. The imbalance of pro- and antiangiogenic circulatory factors contributes to the pathophysiology of preeclampsia. Several studies have examined the profile of angiogenic factors in preeclampsia to search for a biomarker that will improve the diagnostic ability of preeclampsia and associated adverse outcomes. This may help in more efficient patient management and the reduction of associated health care costs. This article reviews the findings from previous studies published to date on angiogenic factors and suggests a need to apply a multivariable model from the beginning of pregnancy and continuing throughout gestation for the early and specific prediction of preeclampsia.
Preeclampsia is a major complication of pregnancy manifested as hypertension and often intrauterine growth restriction, but the underlying pathophysiological mechanisms are unclear. Predisposing genetic and environmental factors cause placental maladaptations leading to defective placentation, apoptosis of invasive cytotrophoblasts, inadequate expansive remodeling of the spiral arteries, reduced uteroplacental perfusion pressure and placental ischemia. Placental ischemia promotes the release of bioactive factors into the maternal circulation, causing an imbalance between anti-angiogenic soluble fms-like tyrosine kinase-1 and soluble endoglin, and pro-angiogenic vascular endothelial growth factor, placental growth factor and transforming growth factor-β. Placental ischemia also stimulates the release of proinflammatory cytokines, hypoxia-inducible factor, reactive oxygen species, and angiotensin type 1 receptor agonistic autoantibodies. These circulating factors target the vascular endothelium, causing generalized endotheliosis in systemic, renal, cerebral and hepatic vessels, leading to decreases in endothelium-derived vasodilators such as nitric oxide, prostacyclin and hyperpolarization factor, and increases in vasoconstrictors such as endothelin-1 and thromboxane A2. The bioactive factors also target vascular smooth muscle and enhance the mechanisms of vascular contraction including cytosolic Ca ²⁺ , protein kinase C and Rho-kinase. The bioactive factors could also target matrix metalloproteinases and the extracellular matrix causing inadequate vascular remodeling, increased arterial stiffening, and further increases in vascular resistance and hypertension. As therapeutic options are limited, understanding the underlying vascular mechanisms and molecular targets should help design new tools for the detection and management of hypertension in pregnancy and preeclampsia.
Elevated circulating sFLT-1 (soluble fms-like tyrosine kinase) and low levels of its ligand, PlGF (placental growth factor), are key characteristics of preeclampsia. However, it is unclear if the low levels of plasma PlGF noted during preeclampsia are due to decreased placental production of PlGF or due to binding of PlGF by increased circulating sFLT-1. Here, we describe a biochemical procedure to dissociate PlGF-sFLT-1 complex ex vivo and when used in conjunction with an immunoassay platform, demonstrate a method to measure total and free PlGF in human blood samples. Using this method, we noted that plasma free PlGF levels were significantly lower in preeclampsia (N=22) than in nonhypertensive controls (N=24; mean, 314 versus 686 pg/mL, P<0.05), but total PlGF levels were not different (mean, 822 versus 800 pg/mL, P=0.49). In contrast, total sFLT-1 levels were significantly higher in preeclampsia than in nonhypertensive controls (mean, 16 957 versus 3029 pg/mL, P<0.01) and sFLT-1 levels correlated with bound PlGF levels (bound PlGF=total PlGF-free PlGF) in these samples (r2=0.68). We confirmed these findings in an independent cohort of subjects (N=49). Furthermore, we did not detect any difference in PlGF mRNA by quantitative polymerase chain reaction or in PlGF protein expression by immunohistochemistry in preeclamptic placentas when compared with nonhypertensive controls. In contrast, sFLT-1 mRNA and protein levels were upregulated in placentas from women with preeclampsia. Taken together with prior studies, our results provide evidence that decrease in circulating PlGF noted during preeclampsia is largely mediated by excess circulating sFLT-1.
Preeclampsia is a potentially life-threatening multisystem disease affecting 4% to 8% of pregnant women after the 20th week of gestation. An excess of placental expressed antiangiogenic soluble VEGF (vascular endothelial growth factor)-receptor 1 (soluble FMS-like tyrosine kinase 1) scavenges VEGF and PlGF (placental growth factor), causing generalized endothelial dysfunction. Interventions to restore the angiogenic balance in preeclamptic pregnancies are intensively studied and improve maternal and neonatal outcomes. Especially extracorporeal strategies to remove sFlt-1 are promising in human pregnancy. However, available apheresis systems adsorb sFlt-1 unspecifically and with low efficiency. Affinity-enhanced ligands are needed to improve performance and compatibility of apheresis treatments. Using computerized molecular modeling, we developed multimeric VEGF molecules comprised of single-chain VEGF ¹⁶⁵ dimers (scVEGF ¹⁶⁵ ). A short peptide linker hampers intrachain dimerization to induce assembly preferably as tetrameric molecules as visualized in negative staining electron microscopy. scVEGF ¹⁶⁵ multimers possess 1.2-fold higher affinity for sFlt-1 as compared to the available antibodies or monomeric VEGF. Consequently, scVEGF multimers have the ability to competitively release sFlt-1 bound PlGF and, in particular, VEGF. In ex vivo adsorption experiments using serum samples from patients with preeclampsia, scVEGF multimers reduce sFlt-1 levels by 85% and increase PlGF and VEGF levels by 20- and 9-fold, respectively. Finally, performance and stability of sFlt-1 capturing scVEGF ¹⁶⁵ multimers were scrutinized on different matrices of which biocompatible agarose matrix yielded optimal results. We introduce the first VEGF-based highly efficient sFlt-1 apheresis system that is directly applicable in vivo due to utilization of inert agarose matrix, using a homomultimeric form of VEGF ¹⁶⁵ to restore the angiogenic balance in preeclampsia.
Preeclampsia (PE) is a serious pregnancy complication, affecting about 5–7% of pregnancies worldwide and is characterized by hypertension and damage to multiple maternal organs, primarily the liver and kidneys. PE usually begins after 20 weeks’ gestation and, if left untreated, can lead to serious complications and lifelong disabilities—even death—in both the mother and the infant. As delivery is the only cure for the disease, treatment is primarily focused on the management of blood pressure and other clinical symptoms. The pathogenesis of PE is still not clear. Abnormal spiral artery remodeling, placental ischemia and a resulting increase in the circulating levels of vascular endothelial growth factor receptor-1 (VEGFR-1), also called soluble fms-like tyrosine kinase-1 (sFlt-1), are believed to be among the primary pathologies associated with PE. sFlt-1 is produced mainly in the placenta during pregnancy and acts as a decoy receptor, binding to free VEGF (VEGF-A) and placental growth factor (PlGF), resulting in the decreased bioavailability of each to target cells. Despite the pathogenic effects of increased sFlt-1 on the maternal vasculature, recent studies from our laboratory and others have strongly indicated that the increase in sFlt-1 in PE may fulfill critical protective functions in preeclamptic pregnancies. Thus, further studies on the roles of sFlt-1 in normal and preeclamptic pregnancies are warranted for the development of therapeutic strategies targeting VEGF signaling for the treatment of PE. Another impediment to the treatment of PE is the lack of suitable methods for delivery of cargo to placental cells, as PE is believed to be of placental origin and most available therapies for PE adversely impact both the mother and the fetus. The present review discusses the pathogenesis of PE, the complex role of sFlt-1 in maternal disease and fetal protection, and the recently developed placenta-targeted drug delivery system for the potential treatment of PE with candidate therapeutic agents.
Introduction:
Preeclampsia is strongly associated with placental hypoperfusion. Genetic factors have an impact on the pathogenesis of preeclampsia. The aim is to assess the association of Vascular Endothelial Growth Factor (C2578A) gene polymorphism with the occurrence and severity of preeclampsia and the umbilical artery Doppler changes among preeclamptic women.
Materials and methods:
This case-control study was conducted in clinical and Chemical pathology and Obstetrics departments in Beni- Suef University, Egypt. Two hundred and ninety pregnant women above 20 weeks gestational age until delivery were divided into 2 main groups. The patient group included 145 preeclamptic women who were further sub grouped according to the severity of preeclampsia into 82 severe and 63 mild cases. Control group included 145 normotensive pregnant women. Our primary outcome was detection of VEGF C 2578 A gene mutations by a polymerase chain reaction. A secondary outcome was Doppler changes in the pulsatility index of the umbilical artery compared with VEGF genotypes.
Results:
Our study showed that VEGF C 2578 A genotype and alleles frequencies were not related to the occurrence of preeclampsia (p-value 0.513 and 0.549, respectively), odds ratio (95%CI) 1.154 (0.724-1.848). Mild preeclamptic cases showed no significance comparing VEGF genotypes studied and pulsatility index of the umbilical artery. However, severe cases showed p-value < 0.0001.
Conclusion:
We concluded that VEGF 2578C/A polymorphism had no association with the occurrence of preeclampsia in studied groups, whereas there was a significant relationship among severe cases between CA and CC genotypes and pulsatility index of the umbilical artery.
Objectives: The aim of this study was to assess the genetic association between vascular endothelial growth factor (VEGF) gene polymorphisms and the risk of pre-eclampsia (PE).
Methods: A systematic literature search of several databases (PubMed, Embase, and the China National Knowledge Infrastructure (CNKI)) was conducted for case–control trials comparing VEGF polymorphisms (+936C/T, −634G/C, −2578C/A, and −1154G/A) with the risk of PE. Meta-analysis was performed using the Stata 12.0 software.
Results: Twenty-three case–control studies on a total of 2597 PE patients and 3075 controls were included in our meta-analysis. The +936C/T polymorphism was observed to be associated with the risk of PE in the overall population (T vs. C: odds ratios (OR) = 1.434, 95% confidence interval (CI) = 1.120–1.836, P = .004). However, the −634G/C, −2578C/A, and −1154G/A polymorphisms showed no association with the risk of PE. A subgroup analysis based on ethnicity found that the +936C/T polymorphism was associated with the risk of PE in both Europeans and Asians. Furthermore, the −634G/C polymorphism was found to be associated with the risk of PE in Europeans (C vs. G: OR = 1.428, 95% CI = 1.141–1.778, P = .002). The polymorphisms at other loci were not associated with the risk of PE.
Conclusion: This meta-analysis suggests that VEGF +936C/T polymorphism, rather than −634G/C, −2578C/A, or −1154G/A polymorphisms, is associated with the risk of PE in the overall study population. However, the −634G/C polymorphism may be associated with the risk of developing PE in Europeans.
Preeclampsia is a pregnancy‐related disorder characterized by hypertension and often fetal intrauterine growth restriction, but the underlying mechanisms are unclear. Defective placentation and apoptosis of invasive cytotrophoblasts cause inadequate remodeling of spiral arteries, placental ischemia and reduced uterine perfusion pressure (RUPP). RUPP causes imbalance between the anti‐angiogenic factors soluble fms‐like tyrosine kinase‐1 and soluble endoglin and the pro‐angiogenic vascular endothelial growth factor and placental growth factor, and stimulates the release of proinflammatory cytokines, hypoxia‐inducible factor, reactive oxygen species, and angiotensin AT1 receptor agonistic autoantibodies. These circulating factors target the vascular endothelium, smooth muscle and various components of the extracellular matrix. Generalized endotheliosis in systemic, renal, cerebral and hepatic vessels causes decreases in endothelium‐derived vasodilators such as nitric oxide, prostacyclin and hyperpolarization factor, and increases in vasoconstrictors such as endothelin‐1 and thromboxane A2. Enhanced mechanisms of vascular smooth muscle contraction such as intracellular Ca²⁺, protein kinase C and Rho‐kinase cause further increases in vasoconstriction. Changes in matrix metalloproteinases and extracellular matrix cause inadequate vascular remodeling and increased arterial stiffening, leading to further increases in vascular resistance and hypertension. Therapeutic options are currently limited, but understanding the molecular determinants of microvascular dysfunction could help in the design of new approaches for the prediction and management of preeclampsia.
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Preeclampsia is a form of hypertension-in-pregnancy (HTN-Preg) with unclear mechanism. Generalized reduction of uterine perfusion pressure (RUPP) could be an initiating event leading to uteroplacental ischemia, angiogenic imbalance, and HTN-Preg. Additional regional differences in uteroplacental blood flow could further affect the pregnancy outcome and increase the risk of preeclampsia in twin or multiple pregnancy, but the mechanisms involved are unclear. To test the hypothesis that regional differences in angiogenic balance and matrix metalloproteinases (MMPs) underlie regional uteroplacental vascularization and feto-placental development, we compared fetal and placental growth, and placental and myoendometrial vascularization in the proximal, middle and distal regions of the uterus (in relation to the iliac bifurcation) in normal pregnant (Preg) and RUPP rats. Maternal blood pressure and plasma anti-angiogenic soluble fms-like tyrosine kinase-1 (sFlt-1)/placenta growth factor (PIGF) ratio were higher, and average placentae number, placenta weight, litter size, and pup weight were less in RUPP than Preg rats. The placenta and pup number and weight were reduced, while the number and diameter of placental and adjacent myoendometrial arteries, and MMP-2 and MMP-9 levels/activity were increased, and sFlt-1/PlGF ratio was decreased in distal vs proximal uterus of Preg rats. In RUPP rats, the placenta and pup number and weight, the number and diameter of placental and myoendometrial arteries, and MMP-2 and -9 levels/activity were decreased, and sFlt-1/PlGF ratio was increased in distal vs proximal uterus. Treatment with sFlt-1 or RUPP placenta extract decreased MMP-2 and MMP-9 in distal segments of Preg uterus, and treatment with PIGF or Preg placenta extract restored MMP levels in distal segments of RUPP uterus. Thus, in addition to the general reduction in placental and fetal growth during uteroplacental ischemia, localized angiogenic imbalance and diminished MMP-2 and MMP-9 could cause further decrease in placental and myoendometrial vascularization and placental and fetal growth in distal vs proximal uterus of HTN-Preg rats. Regional differences in uteroplacental perfusion, angiogenic balance and MMPs could be a factor in the incidence of preeclampsia in multiple pregnancy.
Normal pregnancy is associated with marked hemodynamic and uterine changes that allow adequate uteroplacental blood flow and uterine expansion for the growing fetus. These pregnancy-associated changes involve significant uteroplacental and vascular remodeling. Matrix metalloproteinases (MMPs) are important regulators of vascular and uterine remodeling. Increases in MMP-2 and MMP-9 have been implicated in vasodilation, placentation, and uterine expansion during normal pregnancy. The increases in MMPs could be induced by the increased production of estrogen and progesterone during pregnancy. MMP expression/activity may be altered during complications of pregnancy. Decreased vascular MMP-2 and MMP-9 may lead to decreased vasodilation, increased vasoconstriction, hypertensive pregnancy, and preeclampsia. Abnormal expression of uteroplacental integrins, cytokines, and MMPs may lead to decreased maternal tolerance, apoptosis of invasive trophoblast cells, inadequate remodeling of spiral arteries, and reduced uterine perfusion pressure (RUPP). RUPP may cause imbalance between the antiangiogenic factors soluble fms-like tyrosine kinase-1 and soluble endoglin and the proangiogenic vascular endothelial growth factor and placental growth factor, or stimulate the release of inflammatory cytokines, hypoxia-inducible factor, reactive oxygen species, and angiotensin AT1 receptor agonistic autoantibodies. These circulating factors could target MMPs in the extracellular matrix as well as endothelial and vascular smooth muscle cells, causing generalized vascular dysfunction, increased vasoconstriction and hypertension in pregnancy. MMP activity can also be altered by endogenous tissue inhibitors of metalloproteinases (TIMPs) and changes in the MMP/TIMP ratio. In addition to their vascular effects, decreases in expression/activity of MMP-2 and MMP-9 in the uterus could impede uterine growth and expansion and lead to premature labor. Understanding the role of MMPs in uteroplacental and vascular remodeling and function could help design new approaches for prediction and management of preeclampsia and premature labor.
Objective:
To measure and correlate the level of vascular endothelial growth factors A, C, and D in HIV-associated pre-eclampsia.
Methods:
VEGF-A, VEGF-C, and VEGF-D were measured in serum of 76 normotensive and pre-eclamptic pregnant women stratified by HIV status using Bio-Plex.
Results:
No significant difference was shown between pre-eclamptic and normotensive and between HIV negative and positive women. A strong significant positive correlation was demonstrated between VEGF-A and VEGF-C, VEGF-A and VEGF-D, and VEGF-C and VEGF D (p < 0.0001).
Conclusion:
This study demonstrates a significant correlation between VEGF-A, VEGF-C, and VEGF-D and no difference in pre-eclamptic and normotensive pregnant women stratified by HIV status suggesting some neutralization of the immune response in HIV-associated pre-eclampsia.
Preeclampsia is a pregnancy-associated disorder characterized by hypertension with uncertain pathogenesis. Increases in antiangiogenic soluble fms-like tyrosine kinase-1 (sFlt-1) and reductions in nitric oxide (NO) bioavailability have been observed in preeclamptic women. However, the specific mechanisms linking these detrimental changes to the hypertension-in-pregnancy are not clearly understood. In this regard, while recent findings have suggested that nitrite-derived NO formation exerts antihypertensive and antioxidant effects, no previous study has examined these responses to orally administered nitrite in hypertension-in-pregnancy. We then hypothesized restoring NO bioavailability with sodium nitrite in pregnant rats upon NO synthesis inhibition with N(omega)-nitro-l-arginine methyl ester (L-NAME) attenuates hypertension and high circulating levels of sFlt-1. Number and weight of pups and placentae were recorded to assess maternal-fetal interface. Plasma sFlt-1, vascular endothelial growth factor (VEGF) and biochemical determinants of NO formation and of antioxidant function were measured. We found that sodium nitrite blunts the hypertension-in-pregnancy and restores the NO bioavailability, and concomitantly prevents the L-NAME-induced high circulating sFlt-1 and VEGF levels. Also, our results suggest that nitrite-derived NO protected against reductions in litter size and placental weight caused by L-NAME, improving number of viable and resorbed fetuses and antioxidant function. Therefore, the present findings are consistent with the hypothesis that nitrite-derived NO may possibly be the driving force behind the maternal and fetal beneficial effects observed with sodium nitrite during hypertension-in-pregnancy. Certainly further investigations are required in preeclampsia, since counteracting the damages to the mother and fetal sides resulting from hypertension and elevated sFlt-1 levels may provide a great benefit in this gestational hypertensive disease.
Background Normal pregnancy relies on a careful balance between immune tolerance and suppression. It is known that strict regulation of maternal immune function, in addition to components of inflammation, is paramount to successful pregnancy, and any imbalance between proinflammatory and anti-inflammatory cytokines and chemokines can lead to aberrant inflammation, often seen in complicated pregnancies. Inflammation in complicated pregnancies is directly associated with increased mortality and morbidity of the mother and offspring. Aberrant inflammatory reactions in complicated pregnancies often lead to adverse outcomes, such as spontaneous abortion, preterm labor, intrauterine growth restriction, and fetal demise. The role of inflammation in different stages of normal pregnancy is reviewed, compared, and contrasted with aberrant inflammation in complicated pregnancies. The complications addressed are preterm labor, pregnancy loss, infection, preeclampsia, maternal obesity, gestational diabetes mellitus, autoimmune diseases, and inflammatory bowel disease. Aim This article examines the role of various inflammatory factors contributing to aberrant inflammation in complicated pregnancies. By understanding the aberrant inflammatory process in complicated pregnancies, novel diagnostic tools and therapeutic interventions for modulating it appropriately can be identified.
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This review article will be published in American Journal of Perinatology - it discusses recent advancements in Inflammation state affecting complicated pregnancy.
Introduction The placenta, an organ of fetal origin, is critical to the normal growth and development of a healthy baby. Among its manifold functions, the placenta maintains a complex interface between the fetal and maternal circulations allowing gas exchange, absorption of nutrients, and elimination of waste. As a result of these key transport functions, the placental circulation is a dynamic network of blood vessels that evolves and remodels throughout the course of pregnancy, responding to the growing needs of the embryo and fetus at each step of its development. In this chapter, we will use a loose interpretation of ‘placental angiogenesis’ to include placental neovascular formation as well as transformation of the vessels during gestation. Classically, the de novo formation of blood vessels in the placental villi is called vasculogenesis [1], and occurs during the first trimester of pregnancy. Angiogenesis refers to the transformation of these blood vessels and their adaptation to the increasing transport needs of the fetus, and occurs from the second trimester to term. Another phenomenon critical for the development of the placenta involves the proper invasion of the uterine tissue by trophoblastic cells and the transformation of the maternal spiral arteries. Failure of this phenomenon leads to significant clinical complications of pregnancy like miscarriage, intrauterine growth restriction (IUGR), and preeclampsia (PE), as discussed in other chapters of this book.
The aim of this study was to determine the maternal serum aVEGF-A and its soluble receptor type 1 (sVEGFR-1, sFlt-1) concentrations in pregnancies with intrauterine growth restriction (IUGR) in the presence or absence of preeclampsia. The study was performed on 65 normotensive pregnant patients with isolated IUGR, 64 preeclamptic women with IUGR and 51 preeclamptic patients with normal intrauterine foetal growth and 65 healthy normotensive pregnant women with singleton uncomplicated pregnancies. The maternal serum active VEGF and sVEGFR-1 concentrations were determined using a sandwich enzyme-linked immunosorbent assays. The study revealed increased levels of aVEGF-A in patients with pregnancies complicated by preeclampsia and/or IUGR. But these differences were not statistically significant. The levels of aVEGF-A were decreased in the patients with HELLP syndrome and in the subgroup of patients with pregnancy complicated by eclampsia. This study revealed the higher serum sFlt-1 levels in both groups of preeclamptic patients and similar levels of sVEGFR-1 in normotensive patients with isolated IUGR to those observed in the control group. Findings presented in this study confirm the importance of aVEGF-A for the physiological course of pregnancy. Increased levels of sVEGFR-1, appear to be an important limitation, which may have a significant impact on the pathogenesis of severe preeclampsia and IUGR in the course of preeclampsia. Importantly, IUGR without preeclampsia does not present significant differences relative to physiological control for sVEGFR-1 levels, suggesting different aetiopathogenetic mechanisms leading to "pure" IUGR.
From a broad perspective there are only three arterial systems that respond to relative hypoxia with vasoconstriction. They are the placental, the pulmonic and the renal vascular beds. The renal system's adaptation to hypoxia is markedly different from the other two circulatory beds and will not be further considered here. Regional vasoconstriction is adaptive in the placenta and lung because it redirects red blood cells from areas of relative hypoxia to more oxygenated areas thereby maximizing oxygen uptake for a given cardiac output. The fetal placental and pulmonary vascular systems are unique because their smooth muscle cells have a unique and possibly identical potassium channel that responds to hypoxia by closing, thereby depolarizing the cell membrane allowing calcium ion influx and muscle contraction. It may be that a variety of initial causes of temporary or local placental hypoxia initiate a cascade of first fetal placental then maternal vasoconstriction and endothelial activation leading to the clinical syndrome we call preeclampsia. The response cascades seen in preeclampsia, which for purposes of this article I will abbreviate as (PECL), after development of widespread vasoconstriction, will also be seen to be identical or at least parallel in pulmonary hypertension (PAH). This means that some or all of the pharmacotherapies presently used, tested or considered in early PAH may also have a therapeutic effect in PECL by reducing fetal placental arterial resistance thereby increasing fetal placental flow. This would allow increased oxygen and other nutrient uptake and possibly increased fetal cardiac output in the face of reduced fetal cardiac work. This may allow a delay in delivery in which fetuses grow and are better oxygenated in preterm PECL, improving neonatal outcomes.
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Vascular endothelial cell growth factor, a mitogen selective for vascular endothelial cells in vitro that promotes angiogenesis in vivo, functions through distinct membrane-spanning tyrosine kinase receptors. The cDNA encoding a soluble truncated form of one such receptor, fms-like tyrosine kinase receptor, has been cloned from a human vascular endothelial cell library. The mRNA coding region distinctive to this cDNA has been confirmed to be present in vascular endothelial cells. Soluble fms-like tyrosine kinase receptor mRNA, generated by alternative splicing of the same pre-mRNA used to produce the full-length membrane-spanning receptor, encodes the six N-terminal immunoglobulin-like extracellular ligand-binding domains but does not encode the last such domain, transmembrane-spanning region, and intracellular tyrosine kinase domains. The recombinant soluble human receptor binds vascular endothelial cell growth factor with high affinity and inhibits its mitogenic activity for vascular endothelial cells; thus this soluble receptor could act as an efficient specific antagonist of vascular endothelial cell growth factor in vivo.
Angiogenesis is essential in physiological processes including ovulation, implantation and pregnancy. One of the most potent regulators is the cytokine vascular endothelial growth factor (VEGF). We provide evidence for a novel pregnancy-associated soluble variant of the VEGF receptor Flt-1. VEGF ranged from undetectable to 157.3 pg/ml (mean 49.9 pg/ml, SD 48.4 pg/ml) in plasma samples from normal volunteers (n = 10), but was undetectable in plasma from pregnant women (n = 12) and amniotic fluid (n = 10). Recoveries of spiked VEGF were poor in pregnancy-related samples, indicating the presence of VEGF-binding activity which was confirmed using biosensor and chromatographic techniques. Partial purification and protein sequencing indicated a novel soluble form of Flt-1 with a subunit size of 150 kDa. Normally present as a multimeric structure of approximately 400-550 kDa, complexes of 600-700 kDa were formed following binding of multiple VEGF molecules. Reverse transcriptase polymerase chain reaction of Flt-1 in placenta, amnion, chorion, human umbilical vein endothelial cells and cord blood samples produced bands of the predicted sizes but failed to identify any additional RNA species, and possible reasons for this are discussed. Soluble Flt-1 may be important in regulating the actions of VEGF in angiogenesis and trophoblast invasion and may have therapeutic implications in diseases with inappropriate angiogenesis such as proliferative retinopathies and cancer.
Vascular endothelial growth factor (VEGF) is a potent secreted factor that promotes angiogenesis and maintains the integrity of the endothelium. Levels of VEGF are increased in many tumors and are elevated in women with pre-eclampsia, a serious disease of pregnancy. Here we show by in situ hybridization that the trophoblast contains the mRNA encoding a soluble version of the VEGF receptor known as Flt-1 (sFlt-1: initially described by Kendall and Thomas, PNAS 90:10705-10709). Binding assays and Western blotting of villus-conditioned media confirmed the production of sFlt-1. Serum from pregnant women was found to contain a VEGF-binding protein that was not present in serum from men or nonpregnant women. As determined by heparin affinity, column fractionation, and cross-linking, this protein was identical to sFlt-1. Taken together, these results show that the placenta secretes sFlt-1, which would be expected to be a VEGF antagonist. This is the first report of production of the sFlt-1 receptor in vivo, and it reveals a new mechanism for naturally regulating this potent angiogenic agent. The presence of such an antagonist suggests that regulation of VEGF action is essential to successful pregnancy. This has important implications for the activity of VEGF locally and systemically in other conditions.
Uteroplacental spiral arteries in placental bed biopsies and placentas from 80 pregnancies were studied by light and electron microscopy; of these 30 were complicated by fetal growth retardation (less than 10th centile) and 45 by hypertension during pregnancy. The physiological changes of the spiral arteries and the vascular pathology present in hypertensive pregnancy and fetal growth retardation were investigated. In normotensive pregnancies complicated by fetal growth retardation, the physiological changes of pregnancy frequently did not extend beyond the decidual segments of the utero-placental arteries. In pregnancies complicated by pre-eclampsia, the physiological changes of pregnancy were not always restricted to the decidual segments of the utero-placental arteries. Athero-matous-like lesions of similar morphology were found in spiral arteries from both normotensive and hypertensive pregnancies complicated by fetal growth retardation. No arteriopathy was found which was specific for 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°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.
The investigation of the histology of the placental bed spiral arteries in normal pregnancy and in pregnancies complicated by hypertension, with or without proteinura.
An observational study, based on women having caesarean sections for clinical reasons.
17 normal pregnant women, 43 with gestational hypertension, of whom 39 had proteinuria, 17 with chronic hypertension, of whom 6 had proteinuria, and 5 with unclassified hypertension.
Placental bed biopsies obtained during caesarean section.
Histological appearance of sections stained with haematoxylin and eosin PAS and Lendrum's MSB.
Biopsies containing spiral arteries were obtained from 6 normotensive and 44 hypertensive women. Trophoblastic invasion was present in 5 of the 6 normotensive biopsies but absent in the majority of those with hypertension. Subintimal proliferation was seen in all the normotensive biopsies but in only 8 of 28 from those with gestational hypertension and proteinuria. Other features seen predominantly or only in the hypertensive biopsies, in order of frequency, were medial hyperplasia, fibrin deposits, acute atherosis, endothelial vacuolation and thrombosis.
Absence of physiological changes may not be peculiar to preeclampsia but may be associated or even a result of various forms of hypertension in pregnancy. Spiral arteries show a spectrum of changes in hypertensive pregnancies that do not appear to bear a clear-cut relation to the clinical signs.
Despite intense study preeclampsia remains enigmatic and a major cause of maternal and fetal morbidity and mortality. Most investigative efforts have focused on the hypertensive component of this disorder with reduced attention given to other equally important characteristics. Increased sensitivity to pressor agents and activation of the coagulation cascade occur early in the course of preeclampsia, often antedating clinically recognizable disease. Inasmuch as endothelial cell injury reduces the synthesis of vasorelaxing agents, increases the production of vasoconstrictors, impairs synthesis of endogenous anticoagulants, and increases procoagulant production, these cells are likely to be implicated in the pathophysiology of preeclampsia. Indeed, evidence of endothelial cell injury is provided by the most characteristic morphologic lesion of preeclampsia, glomerular endotheliosis. Additional support for this hypothesis is derived from reports that indicate increased levels of circulating fibronectin (which can be released from injured endothelial cells) and increased factor VIII antigen present in the blood of preeclamptic women. More recently, direct evidence of activities that injure endothelial cells in vitro and increase the contractile sensitivity of isolated vessels has been presented. We propose that poorly perfused placental tissue releases a factor(s) into the systemic circulation that injuries endothelial cells. The changes initiated by endothelial cell injury set in motion a dysfunctional cascade of coagulation, vasoconstriction, and intravascular fluid redistribution that results in the clinical syndrome of preeclampsia.
Preeclampsia occurs in 7% to 10% of pregnancies and is a leading cause of morbidity for mothers and their infants. Intensive investigation has failed to reveal the cause of the multiple organ dysfunction characteristic of this disorder, which abates completely with delivery. However, several observations suggest that endothelial cell dysfunction is a central pathophysiologic event. We report that serum from preeclamptic women is cytotoxic to endothelial cells in vitro. Consistent with the reversal of the clinical condition after delivery, cytotoxic activity in serum of preeclamptic women is reduced after 24 to 48 hours post partum. In contrast, cytotoxic activity of serum from normal pregnant women increases after delivery.
Uteroplacental spiral arteries in placental bed biopsies and placentas form 80 pregnancies were studied by light and electron microscopy; of these 30 were complicated by fatal growth retardation(less than 10th centile) and 45 by hypertension during pregnancy. The physiological changes of the spiral arteries and the vascular pathology present in hypertensive pregnancy and fetal growth retardation were investigated. In normotensive pregnancies complicated by fetal growth retardation, the physiological changes of pregnancy frequently did not extend beyond the decidual segments of the utero-placental arteries. In pregnancies complicated by pre-eclampsia, the physiological changes of pregnancy were not always restricted to the decidual segments of the utero-placental arteries. Atheromatous-like lesions of similar morphology were found in spiral arteries from both normotensive and hypertensive pregnancies complicated by fetal growth retardation. No arteriopathy was found which was specific for pre-eclampsia.
To determine whether altered levels of vascular endothelial growth factor (VEGF) may be implicated in the pathogenesis of preeclampsia, and whether VEGF mediates the endothelial cell activation that is involved in the pathogenesis of the clinical syndrome.
In a cross-sectional study, maternal serum samples in late pregnancy (at the time of clinical disease) were collected from 78 nulliparous women. These subjects were subdivided into those with preeclampsia (n = 27), nonproteinuric pregnancy-induced hypertension (n = 15), and normal pregnant women (n = 36). In a nested case-control study, in addition to samples taken before delivery, samples were obtained in early pregnancy (before clinical disease) and 24-48 hours postpartum from 12 of the patients with preeclampsia, 12 of those with nonproteinuric pregnancy-induced hypertension, and 12 of the normal pregnant subjects. Umbilical cord blood was sampled from 14 of the preeclamptic and 16 of the normal pregnant subjects. We measured VEGF levels in all samples using an immunofluorometric assay.
In most samples collected before delivery, VEGF levels were below the lower limit of detection. However, the proportion of detectable levels was higher in the preeclampsia group (seven of 27) than in the normotensive group (one of 36, P < .05). The proportion in the nonproteinuric pregnancy-induced hypertension group (two of 15) did not differ significantly from the other groups. Levels in the patients with preeclampsia were not elevated before clinical disease. Levels of VEGF in umbilical blood samples were higher than in maternal venous blood, although there were no significant differences between groups.
Serum VEGF levels were elevated in patients with preeclampsia, which suggests that the growth factor has a role in the endothelial cell activation that occurs in the disease.
Vascular endothelial growth factor (VEGF) is a specific endothelial cell mitogen with potent angiogenic properties. In tumors, VEGF has been localized to the most necrotic and ischemic areas of the tissues, suggesting that local hypoxia is a potent inducer of VEGF production. Initial experiments in vitro confirmed the stimulatory effect of hypoxia on VEGF expression. The extent of this response and the mechanisms involved in oxygen sensing are poorly characterized.
Confluent monolayers of malignant cell lines or primary cultures of fibroblast or endothelial cells were exposed to hypoxia or incubated with either cobalt chloride, a stimulator of erythropoietin gene expression, or sodium azide, an inhibitor of oxydative phosphorylation. VEGF expression was analyzed by Northern blot or RNase protection assays. The expression VEGF in vivo was studied in animals subjected to hypobaric hypoxia or functional anemia.
Hypoxia greatly stimulated VEGF expression in tumor cell lines and primary fibroblast cultures. Endothelial cells, that expressed very low constitutive levels of VEGF, were resistant to hypoxic stimulation. RNase protection analysis showed that hypoxia primarily stimulated the induction of smaller and medium VEGF isoforms, i.e., the same ones expressed under normal conditions. The stimulatory effect of hypoxia on VEGF could be reproduced in vitro by cobalt chloride but not with sodium azide. In vivo, both hypoxia and anemia were found to be potent inducers of VEGF expression in several organs including heart, brain, liver, kidney, and muscle. As in vitro, cobalt was also found to be a potent stimulator of VEGF in vivo.
Hypoxia is a potent inducer of VEGF expression in malignant as well as normal cultured cells. It is also a stimulator of VEGF expression in vivo. The VEGF gene appears to respond to hypoxia like the erythropoietin gene, and the mechanism of oxygen sensing probably is mediated by a heme-containing protein.
During normal human pregnancy a subpopulation of fetal cytotrophoblast stem cells differentiate and invade the uterus and its arterioles. In the pregnancy disease preeclampsia, cytotrophoblast differentiation is abnormal and invasion is shallow. Thus, the placenta is relatively hypoxic. We investigated whether lowering oxygen tension affects cytotrophoblast differentiation and invasion. Previously we showed that when early gestation cytotrophoblast stem cells are cultured under standard conditions (20% O2) they differentiate/invade, replicating many aspects of the in vivo process. Specifically, the cells proliferate at a low rate and rapidly invade extracellular matrix (ECM) substrates, a phenomenon that requires switching their repertoire of integrin cell-ECM receptors, which are stage-specific antigens that mark specific transitions in the differentiation process. In this study we found that lowering oxygen tension to 2% did not change many of the cells' basic processes. However, there was a marked increase in their incorporation of [3H]thymidine and 5-bromo-2'-deoxyuridine (BrdU). Moreover, they failed to invade ECM substrates, due at least in part to their inability to completely switch their integrin repertoire. These changes mimic many of the alterations in cytotrophoblast differentiation/invasion that occur in preeclampsia, suggesting that oxygen tension plays an important role in regulating these processes in vivo.
To measure the mRNA levels of vascular endothelial growth factor and its receptor in the placenta following delivery after uncomplicated pregnancy and after pregnancies complicated by pre-eclampsia.
Rosie Maternity Hospital, Cambridge.
Placental biopsies were obtained following delivery by caesarean section in 23 cases of pregnancy presenting at a range of gestational ages with pre-eclampsia. These were compared with biopsies from 20 appropriately matched women with uncomplicated pregnancies.
mRNA levels of vascular endothelial growth factor (VEGF) and its receptor the fins-like tyrosine kinase (flt), were quantified in total RNA isolated from placental biopsies using the RNAse protection assay. The amount of RNA was compared with that of the housekeeping gene glyceraldehyde 3-phosphate dehydrogenase (GAPDH), used as a standard. Results were expressed as arbitrary optical density units of VEGF/GAPDH and flt/GAPDH.
In both control and pre-eclamptic women regression analysis showed that the level of mRNA encoding VEGF declined significantly with gestational age (P < 0.0001). However, levels of VEGF mRNA were significantly lower in the pre-eclamptic women compared with the control women (P < 0.023).
This study provides evidence of an abnormality of growth factor expression in the placenta during pregnancies complicated by pre-eclampsia. Such placentae exhibit deficient growth and differentiation of terminal villi and reduced fetal capillary branching and reduced levels of VEGF could well account for these morphometric changes. This finding provides a molecular explanation for this abnormal placental development and points to VEGF as a factor in the aetiology of pre-eclampsia and its complications.
We have measured the level of vascular endothelial growth factor (VEGF) in maternal plasma during normotensive pregnancy and in pregnancies complicated by pre-eclampsia. VEGF was measured using a competitive enzyme immunoassay. Plasma VEGF was significantly elevated (P < 0.0001) in the pre-eclamptic group (median value 32.7 ng mL-1, range 10.3-64.0), compared with the normotensive group (median value 11.7 ng mL-1, range 6.3-24.3). VEGF is a potent regulator of endothelial cell function. The increased level found in women with pre-eclampsia indicates that VEGF may be involved in the maternal endothelial cell dysfunction associated with this condition. An increase in VEGF, a potent regulator of microvascular permeability, may also contribute to the extravasation of plasma proteins and the subsequent development of proteinuria, both characteristic features of pre-eclampsia.
I. Introduction II. Biological Activities of VEGF III. Organization of the VEGF Gene IV. Properties of the VEGF Isoforms V. Regulation of VEGF Gene Expression A. Hypoxia B. Cytokines C. Differentiation and transformation VI. The VEGF Receptors A. Characterization and distribution of VEGF-binding sites B. The Flt-1 and Flk-1/KDR tyrosine kinases 1. Binding characteristics 2. Signal transduction 3. Regulation 4. Structural requirements for ligand binding in Flt-1 and Flk-1/KDR 5. VEGF determinants for binding Flt-1 and Flk-1/KDR VII. VEGF-Related Molecules VIII. Role of VEGF and Its Receptors in Physiological Angiogenesis A. Distribution of VEGF, Flk-1/KDR and Flt-1 mRNA B. Analysis of Flk-1/KDR, Flt-1 and VEGF gene knockouts IX. Role of VEGF in Pathological Angiogenesis A. Tumor angiogenesis 1. Expression of VEGF in human tumors 2. Inhibition of VEGF action in vivo B. Intraocular neovascular syndromes C. Other pathological conditions X. Therapeutic Applications of VEGF-Induced Angiogenesis XI. Perspectives
To determine whether vascular endothelial growth factor (VEGF) concentrations are altered in pre-eclampsia.
Serum was prepared from peripheral venous blood and stored at -70 degrees C. Serum VEGF concentrations were measured by ELISA.
University of Glasgow Department of Obstetrics and Gynaecology, Royal Infirmary, Glasgow.
Twenty-two healthy nonpregnant volunteer women, 34 normal pregnant women and 34 women with pre-eclampsia were studied.
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).
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.
Using radioimmunoassay (RIA) and a polyclonal antibody we have shown that maternal serum vascular endothelial growth factor (VEGF) is elevated during pregnancy. In contrast, a commercial VEGF ELISA utilizing a sandwich two-site immunoassay was unable to detect VEGF in 19 of the 20 maternal serum samples analysed. In addition, the recovery of exogenous VEGF added to the pregnancy samples was low or not recordable with the ELISA. Using RIA, 82-101% of the added VEGF was recovered. These differing results could be explained by the formation of VEGF-protein complexes that are detectable using RIA but undetectable with the ELISA. Our data imply that there is a substantial increase in circulating VEGF binding proteins during pregnancy. The increase in VEGF and its binding proteins during pregnancy may reflect important physiological events in the mother and feto-placental unit.
1. The objectives of the study were: (i) to investigate the serum concentrations of vascular endothelial growth factor (VEGF) in pregnant and non-pregnant women; and (ii) to study the relationship between the levels of maternal serum VEGF and the serum concentrations of human chorionic gonadotrophin (hCG) and progesterone during the first trimester.
2. Total immunoreactive VEGF was measured by competitive RIA using recombinant human VEGF165 and a polyclonal antiserum. Serum VEGF was measured in 60 non-pregnant women of child-bearing age. These data were compared with serum VEGF measured in 363 women between 41 and 91 days of gestation.
3. The median serum VEGF concentration was 1.10 μg/l (interquartile range 0.91–1.30) in the nonpregnant women and 2.13 μg/l (interquartile range 1.62–2.77) in the pregnant women. Serum levels of VEGF were significantly higher among the pregnant cohort (P < 0.0001). Serum VEGF concentration was positively correlated with gestational age, increasing until ten completed weeks of pregnancy. Serum VEGF was negatively correlated with maternal height and weight, and positively correlated with serum hCG and serum progesterone (P ≤ 0.0001 in all cases). Serum VEGF was lower in the pregnant women who smoked (P = 0.06).
4. Our data show a positive and highly significant correlation between maternal serum levels of VEGF and hormones reflecting placental function (hCG, progesterone). We speculate that VEGF production is increased by progesterone and hCG, and that VEGF has a positive influence on trophoblast development. VEGF may also be involved in the initiation of the maternal cardiovascular adaptation to pregnancy.
This study was conducted to determine whether altered levels of vascular endothelial growth factor (VEGF) may play a role in the pathogenesis of preeclampsia.
Maternal plasma samples were collected from 19 patients with preeclampsia (group A) either before the onset of labor, or before induction of labor or medical intervention. Plasma samples were also obtained from 19 normotensive patients with uncomplicated pregnancies (group B), who were matched with the patients with preeclampsia for gestational age and parity. Samples were frozen at -70 degrees C until assayed for VEGF by a specific enzyme-linked immunoassay.
The mean maternal age was similar in groups A and B. For both groups the VEGF was detectable in all plasma samples. However, the plasma concentrations of VEGF were significantly increased in the group A patients, compared with those in group B (median, 47 ng/ml; range, 10.6-72 ng/ml versus median, 13.6 ng/ml; range, 0.66-20 ng/ml; P < 0.001). In group A, a positive correlation was noted between VEGF concentrations and the systolic and diastolic blood pressure (r = 0.56; P = 0.01 and r = 0.48; P = 0.037, respectively).
Maternal plasma VEGF levels were elevated in the patients with preeclampsia and correlated with the severity of hypertension, suggesting a role for VEGF in the pathogenesis of preeclampsia.
To determine normal values of total plasma fibronectin in all three gestational trimesters and to examine 1) whether total plasma fibronectin levels differ between normotensive, hypertensive, and preeclamptic women; and 2) whether total plasma fibronectin may serve as an early marker of pregnancy-induced hypertensive disorders.
Total plasma fibronectin was measured in 376 nulliparous women once in each trimester of pregnancy. Normotensive controls (n = 222) and subjects with pregnancy-induced hypertensive disorders (n = 154) were identified after delivery. The group with pregnancy-induced hypertensive disorders was subdivided into a gestational hypertensive group (n = 125) and a preeclamptic group (n = 29). A complete total plasma fibronectin data set was obtained from 347 subjects. Trends in total plasma fibronectin values were compared for the different groups and relative risks (RRs) were calculated after optimal cutoff levels had been determined by receiver operating characteristic curves.
Total plasma fibronectin values (+/- standard error of the mean) were 227 +/- 3 mg/L in the first, 219 +/- 3 mg/L in the second, and 260 +/- 5 mg/L in the third trimesters in normotensive pregnancies. In the first trimester and persisting throughout pregnancy, total plasma fibronectin levels were significantly higher in patients with pregnancy-induced hypertensive disorders than in controls and showed a sharper increase throughout pregnancy. Increased first-trimester total plasma fibronectin levels result in an RR of 1.4 (95% confidence interval [CI] 1.1, 1.8) of developing a pregnancy-induced hypertensive disorder in general. The RR for the development of preeclampsia was 1.7 (95% CI 0.9, 3.4), which was not significant, when the first-trimester total plasma fibronectin level was above the cutoff level of 240 mg/L. The RR for developing preeclampsia was 3.8 (95% CI 1.8, 8.0) when the second-trimester total plasma fibronectin level increased above 230 mg/L.
The findings of the present study confirm those of previous studies that have found increased total plasma fibronectin levels in pregnancy-induced hypertensive disorders. This study discovered that in these women, total plasma fibronectin levels are elevated in the first trimester. Total plasma fibronectin appears to be a poor predictor of preeclampsia when measured in a general pregnant population. Therefore, total plasma fibronectin should not be used as a routine screening test in a low-risk population. However, obstetricians may use total plasma fibronectin values to help determine the relative risk of developing pregnancy-induced hypertensive disorders.
Using a competitive radioimmunoassay to measure total immunoreactive vascular endothelial growth factor (VEGF), we describe for the first time longitudinal changes in serum VEGF in early pregnancy. The measurements were obtained from 26 women following the transfer of cryopreserved embryos; 18 singleton and eight twin pregnancies were identified by ultrasound at 6 weeks gestation and subsequently delivered as live births. Subjects did not have corpora lutea and exogenous hormone support was provided for the first 70 days of pregnancy. Serum VEGF increased approximately 30 days after embryo transfer and thereafter continued to rise in both singleton and twin pregnancies over a period of 20-40 days after which concentrations remained elevated. The longitudinal profile of serum VEGF concentrations was characterized by a logistic curve for singleton and twin pregnancies; the profile of VEGF concentrations in the twin pregnancies was significantly higher than in the singleton pregnancies (P < 0.0001). Profiles of the longitudinal concentrations of serum human chorionic gonadotrophin (HCG), oestradiol and progesterone were created by polynomial regression for singleton and twin pregnancies. The VEGF profiles were positively correlated with the profiles of HCG (r = 0.44, P = 0.02) and oestradiol (r = 0.36, P = 0.07) but not progesterone (r = 0.16, P = 0.42). Serum VEGF concentrations in the singleton thawed embryo pregnancies were compared with gestation-matched normal singleton pregnancies with corpora lutea. Concentrations of VEGF were significantly (P = 0.004) greater in the pregnancies with corpora lutea although this difference became less marked with advancing gestation. In addition to its important role in angiogenesis, we speculate that VEGF is involved in mechanisms which control the maternal cardiovascular adaptation to pregnancy.
To compare median levels of maternal serum inhibin A in the second trimester blood samples of women who subsequently develop pre-eclampsia and those who do not.
Retrospective analysis of 13 18 week samples from a bank of serum stored at -40 degrees C, originally taken for Down's syndrome screening.
Antenatal clinics in a teaching hospital.
Twenty-eight pregnancies with pre-eclampsia and 701 controls. Samples were taken, on average, 22 weeks before the diagnosis.
Median inhibin A level.
The median inhibin A level in the cases was 2.01 multiples of the gestation-specific median in the controls, a statistically significant elevation (P < 0.001). Twenty-three (82%) had levels above the normal median; 19 (68%), 15 (54%), and 11 (39%) exceeded the normal 75th, 90th and 95th centiles, respectively.
In pre-eclampsia the maternal serum inhibin A level can be increased months before the onset of symptoms. This provides an opportunity to study the early natural history of the disease and possibly to conduct treatment trials.
Preeclampsia is a multisystem disorder characterized by hypertension and proteinuria. There is accumulating evidence that this is a disease of the endothelium, with an as-yet unidentified circulating factor, or factors, causing the observed alteration in vascular function. We previously reported that the function of myometrial vessels is altered on exposure to plasma from women with preeclampsia. Vascular endothelial growth factor (VEGF) is an angiogenic growth factor that acts via two high-affinity receptors (KDR and Flt-1), and its production is increased in preeclampsia. Here we report that VEGF and its Flt-1 receptor may play a pivotal role in the altered vascular function of preeclampsia. Myometrial resistance vessels were obtained at the time of cesarean section. Using the Mulvany wire myograph, the endothelium-dependent behavior of these vessels was studied. Incubation of vessels from pregnant women with VEGF resulted in a reduction of endothelium-dependent relaxation that mimicked the reduction induced by plasma from women with preeclampsia. The altered function that occurred upon exposure of vessels to VEGF or plasma from women with preeclampsia did not occur when plasma was incubated with antibodies to VEGF before vessel incubation. The presence of an anti-KDR receptor antibody had no effect on VEGF response. However, in the presence of an anti-Flt-1 receptor antibody, VEGF or plasma from women with preeclampsia no longer attenuated the endothelium-dependent relaxation (p < 0.05). The changes observed with VEGF and plasma from women with preeclampsia and their subsequent blockade with anti-VEGF antibody and anti-Flt-1 receptor antibody strongly suggest that VEGF acting through the Flt-1 receptor is pivotal in the pathogenesis of this disease.
Maternal serum VEGF during early pregnancy
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Elevated serum levels of VEGF in patients with PE
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Hypoxia alters early human cytotrophoblasts differentiation/invasion in-vitro and models the placental defects that occur in PE
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- R Joslin
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- B M Polliom
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Placental bed spiral arteries in the hypertensive disorders of pregnancy
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