Increased soluble endoglin levels in newly-diagnosed type 2 diabetic patients are associated with endothelial dysfunction.

Endothelial dysfunction (ED) contributes to the pathologic process underlying macrovascular complications, a common complication of type 2 diabetes mellitus (T2DM). Soluble endoglin (sEng) shed from the extracellular domain of the entire endoglin molecule blocks endothelial protection mediated by transforming growth factor-beta 1 (TGF-ß1). The reactive hyperemia index (RHI), which is determined by reactive hyperemia peripheral arterial tonometry (RH-PAT), is a new index with which to evaluate ED. This study determined the changes in serum sEng levels in newly-diagnosed (untreated) T2DM patients and the correlation with the RHI. The T2DM group included 34 newly-diagnosed T2DM patients, while the control group included 53 healthy adults. The clinical data from the two groups were evaluated retrospectively. The intima-media thickness (IMT) of the common carotid artery (CCA) and the ankle-brachial index (ABI) of both legs were used to assess structural vascular changes. The serum sEng level was determined using an ELISA kit. Endothelial function was assessed using RH-PAT and the RHI was computed. The serum sEng level in the T2DM group was significantly greater than the control group, although the RHI was significantly lower in the T2DM group (p < 0.05). The serum sEng level was negatively correlated with the RHI in T2DM patents (r = 0.354, p = 0.041). The serum sEng level, CCA-IMT, and ABI were not significantly correlated with T2DM (p > 0.05). In summary, among newly-diagnosed T2DM patients, the serum sEng levels were inversely correlated with the RHI, and an elevated sEng level may be associated with ED.

Similar Pro- and Antiangiogenic Profiles Close to Delivery in Different Clinical Presentations of Two Pregnancy Syndromes: Preeclampsia and Fetal Growth Restriction.

The purpose of this study was to evaluate serum levels of anti- and pro-angiogenic substances measured using enzyme-linked immunosorbent assays and their ratios in pregnancies complicated by different clinical subsets of placental ischemic syndrome: preeclampsia and/or fetal growth restriction. A prospective case-control study was performed consisting of 77 singleton pregnancies complicated by preeclampsia, preeclampsia with concurrent fetal growth restriction (FGR), and isolated normotensive FGR pairwise matched by gestational age with healthy pregnancies. The entire study cohort was analyzed with respect to adverse pregnancy outcomes that occurred. In all investigated subgroups, placental growth factor (PlGF) was lower and soluble endoglin (sEng), the soluble fms-like tyrosine kinase-1-sFlt-1/PlGF and sFlt-1*sEng/PlGF ratios were higher than in the control group. The differences were most strongly pronounced in the PE with concurrent FGR group and in the sFlt-1/PlGF ratio. The highest sFlt-1 values in preeclamptic patients suggest that this substance may be responsible for reaching the threshold needed for PE to develop as a maternal manifestation of ischemic placental disease. The FGR is characterized by an elevated maternal sFlt-1/PlGF ratio, which boosts at the moment of indicated delivery due to fetal risk. We concluded that angiogenic imbalance is reflective of placental disease regardless of its clinical manifestation in the mother, and may be used as support for the diagnosis and prognosis of FGR.

The role of endoglin and its soluble form in pathogenesis of preeclampsia.

Preeclampsia remains till today a leading cause of maternal and fetal morbidity and mortality. Pathophysiology of the disease is not yet fully elucidated, though it is evident that it revolves around placenta. Cellular ischemia in the preeclamptic placenta creates an imbalance between angiogenic and anti-angiogenic factors in maternal circulation. Endoglin, a transmembrane co-receptor of transforming growth factor ß (TGF-ß) demonstrating angiogenic effects, is involved in a variety of angiogenesis-dependent diseases with endothelial dysfunction, including preeclampsia. Endoglin expression is up-regulated in preeclamptic placentas, through mechanisms mainly induced by hypoxia, oxidative stress and oxysterol-mediated activation of liver X receptors. Overexpression of endoglin results in an increase of its soluble form in maternal circulation. Soluble endoglin represents the extracellular domain of membrane endoglin, cleaved by the action of metalloproteinases, predominantly matrix metalloproteinase-14. Released in circulation, soluble endoglin interferes in TGF-ß1 and activin receptor-like kinase 1 signaling pathways and inhibits endothelial nitric oxide synthase activation, consequently deranging angiogenesis and promoting vasoconstriction. Due to these properties, soluble endoglin actively contributes to the impaired placentation observed in preeclampsia, as well as to the pathogenesis and manifestation of its clinical signs and symptoms, especially hypertension and proteinuria. The significant role of endoglin and soluble endoglin in pathophysiology of preeclampsia could have prognostic, diagnostic and therapeutic perspectives. Further research is essential to extensively explore the potential use of these molecules in the management of preeclampsia in clinical settings.

The role of statins in the prevention of preeclampsia.

Preeclampsia is a common hypertensive disorder of pregnancy associated with considerable neonatal and maternal morbidities and mortalities. However, the exact cause of preeclampsia remains unknown; it is generally accepted that abnormal placentation resulting in the release of soluble antiangiogenic factors, coupled with increased oxidative stress and inflammation, leads to systemic endothelial dysfunction and the clinical manifestations of the disease. Statins have been found to correct similar pathophysiological pathways that underlie the development of preeclampsia. Pravastatin, specifically, has been reported in various preclinical and clinical studies to reverse the pregnancy-specific angiogenic imbalance associated with preeclampsia, to restore global endothelial health, and to prevent oxidative and inflammatory injury. Human studies have found a favorable safety profile for pravastatin, and more recent evidence does not support the previous teratogenic concerns surrounding statins in pregnancy. With reassuring and positive findings from pilot studies and strong biological plausibility, statins should be investigated in large clinical randomized-controlled trials for the prevention of preeclampsia.

Imbalances in circulating angiogenic factors in the pathophysiology of preeclampsia and related disorders.

Preeclampsia is a devastating medical complication of pregnancy that can lead to significant maternal and fetal morbidity and mortality. It is currently believed that there is abnormal placentation in as early as the first trimester in women destined to develop preeclampsia. Although the etiology of the abnormal placentation is being debated, numerous epidemiologic and experimental studies suggest that imbalances in circulating angiogenic factors released from the placenta are responsible for the maternal signs and symptoms of preeclampsia. In particular, circulating levels of soluble fms-like tyrosine kinase 1, an antiangiogenic factor, are markedly increased in women with preeclampsia, whereas free levels of its ligand, placental, growth factor are markedly diminished. Alterations in these angiogenic factors precede the onset of clinical signs of preeclampsia and correlate with disease severity. Recently, the availability of automated assays for the measurement of angiogenic biomarkers in the plasma, serum, and urine has helped investigators worldwide to demonstrate a key role for these factors in the clinical diagnosis and prediction of preeclampsia. Numerous studies have reported that circulating angiogenic biomarkers have a very high negative predictive value to rule out clinical disease among women with suspected preeclampsia. These blood-based biomarkers have provided a valuable tool to clinicians to accelerate the time to clinical diagnosis and minimize maternal adverse outcomes in women with preeclampsia. Angiogenic biomarkers have also been useful to elucidate the pathogenesis of related disorders of abnormal placentation such as intrauterine growth restriction, intrauterine fetal death, twin-to-twin transfusion syndrome, and fetal hydrops. In summary, the discovery and characterization of angiogenic proteins of placental origin have provided clinicians a noninvasive blood-based tool to monitor placental function and health and for early detection of disorders of placentation. Uncovering the mechanisms of altered angiogenic factors in preeclampsia and related disorders of placentation may provide insights into novel preventive and therapeutic options.

Prediction of preeclampsia throughout gestation with maternal characteristics and biophysical and biochemical markers: a longitudinal study.

BACKGROUND: The current approach to predict preeclampsia combines maternal risk factors and evidence from biophysical markers (mean arterial pressure, Doppler velocimetry of the uterine arteries) and maternal blood proteins (placental growth factor, soluble vascular endothelial growth factor receptor-1, pregnancy-associated plasma protein A). Such models require the transformation of biomarker data into multiples of the mean values by using population- and site-specific models. Previous studies have focused on a narrow window in gestation and have not included the maternal blood concentration of soluble endoglin, an important antiangiogenic factor up-regulated in preeclampsia. OBJECTIVE: This study aimed (1) to develop models for the calculation of multiples of the mean values for mean arterial pressure and biochemical markers; (2) to build and assess the predictive models for preeclampsia based on maternal risk factors, the biophysical (mean arterial pressure) and biochemical (placental growth factor, soluble vascular endothelial growth factor receptor-1, and soluble endoglin) markers collected throughout pregnancy; and (3) to evaluate how prediction accuracy is affected by the presence of chronic hypertension and gestational age. STUDY DESIGN: This longitudinal case-cohort study included 1150 pregnant women: women without preeclampsia with (n=49) and without chronic hypertension (n=871) and those who developed preeclampsia (n=166) or superimposed preeclampsia (n=64). Mean arterial pressure and immunoassay-based maternal plasma placental growth factor, soluble vascular endothelial growth factor receptor-1, and soluble endoglin concentrations were available throughout pregnancy (median of 5 observations per patient). A prior-risk model for preeclampsia was established by using Poisson regression based on maternal characteristics and obstetrical history. Next, multiple regression was used to fit biophysical and biochemical marker data as a function of maternal characteristics by using data collected at 8 to 15+6, 16 to 19+6, 20 to 23+6, 24 to 27+6, 28 to 31+6, and 32 to 36+6 week intervals, and observed values were converted into multiples of the mean values. Then, multivariable prediction models for preeclampsia were fit based on the biomarker multiples of the mean data and prior-risk estimates. Separate models were derived for overall, preterm, and term preeclampsia, which were evaluated by receiver operating characteristic curves and sensitivity at fixed false-positive rates. RESULTS: (1) The inclusion of soluble endoglin in prediction models for all preeclampsia, together with the prior-risk estimates, mean arterial pressure, placental growth factor, and soluble vascular endothelial growth factor receptor-1, increased the sensitivity (at a fixed false-positive rate of 10%) for early prediction of superimposed preeclampsia, with the largest increase (from 44% to 54%) noted at 20 to 23+6 weeks (McNemar test, P<.05); (2) combined evidence from prior-risk estimates and biomarkers predicted preterm preeclampsia with a sensitivity (false-positive rate, 10%) of 55%, 48%, 62%, 72%, and 84% at 8 to 15+6, 16 to 19+6, 20 to 23+6, 24 to 27+6, and 28 to 31+6 week intervals, respectively; (3) the sensitivity for term preeclampsia (false-positive rate, 10%) was 36%, 36%, 41%, 43%, 39%, and 51% at 8 to 15+6, 16 to 19+6, 20 to 23+6, 24 to 27+6, 28 to 31+6, and 32 to 36+6 week intervals, respectively; (4) the detection rate for superimposed preeclampsia among women with chronic hypertension was similar to that in women without chronic hypertension, especially earlier in pregnancy, reaching at most 54% at 20 to 23+6 weeks (false-positive rate, 10%); and (5) prediction models performed comparably to the Fetal Medicine Foundation calculators when the same maternal risk factors and biomarkers (mean arterial pressure, placental growth factor, and soluble vascular endothelial growth factor receptor-1 multiples of the mean values) were used as input. CONCLUSION: We introduced prediction models for preeclampsia throughout pregnancy. These models can be useful to identify women at risk during the first trimester who could benefit from aspirin treatment or later in pregnancy to inform patient management. Relative to prediction performance at 8 to 15+6 weeks, there was a substantial improvement in the detection rate for preterm and term preeclampsia by using data collected after 20 and 32 weeks' gestation, respectively. The inclusion of plasma soluble endoglin improves the early prediction of superimposed preeclampsia, which may be valuable when Doppler velocimetry of the uterine arteries is not available.

Eclampsia in the 21st century.

The reported incidence of eclampsia is 1.6 to 10 per 10,000 deliveries in developed countries, whereas it is 50 to 151 per 10,000 deliveries in developing countries. In addition, low-resource countries have substantially higher rates of maternal and perinatal mortalities and morbidities. This disparity in incidence and pregnancy outcomes may be related to universal access to prenatal care, early detection of preeclampsia, timely delivery, and availability of healthcare resources in developed countries compared to developing countries. Because of its infrequency in developed countries, many obstetrical providers and maternity units have minimal to no experience in the acute management of eclampsia and its complications. Therefore, clear protocols for prevention of eclampsia in those with severe preeclampsia and acute treatment of eclamptic seizures at all levels of healthcare are required for better maternal and neonatal outcomes. Eclamptic seizure will occur in 2% of women with preeclampsia with severe features who are not receiving magnesium sulfate and in <0.6% in those receiving magnesium sulfate. The pathogenesis of an eclamptic seizure is not well understood; however, the blood-brain barrier disruption with the passage of fluid, ions, and plasma protein into the brain parenchyma remains the leading theory. New data suggest that blood-brain barrier permeability may increase by circulating factors found in preeclamptic women plasma, such as vascular endothelial growth factor and placental growth factor. The management of an eclamptic seizure will include supportive care to prevent serious maternal injury, magnesium sulfate for prevention of recurrent seizures, and promoting delivery. Although routine imagining following an eclamptic seizure is not recommended, the classic finding is referred to as the posterior reversible encephalopathy syndrome. Most patients with posterior reversible encephalopathy syndrome will show complete resolution of the imaging finding within 1 to 2 weeks, but routine imaging follow-up is unnecessary unless there are findings of intracranial hemorrhage, infraction, or ongoing neurologic deficit. Eclampsia is associated with increased risk of maternal mortality and morbidity, such as placental abruption, disseminated intravascular coagulation, pulmonary edema, aspiration pneumonia, cardiopulmonary arrest, and acute renal failure. Furthermore, a history of eclamptic seizures may be related to long-term cardiovascular risk and cognitive difficulties related to memory and concentration years after the index pregnancy. Finally, limited data suggest that placental growth factor levels in women with preeclampsia are superior to clinical markers in prediction of adverse pregnancy outcomes. This data may be extrapolated to the prediction of eclampsia in future studies. This summary of available evidence provides data and expert opinion on possible pathogenesis of eclampsia, imaging findings, differential diagnosis, and stepwise approach regarding the management of eclampsia before delivery and after delivery as well as current recommendations for the prevention of eclamptic seizures in women with preeclampsia.

Procyanidin B2 ameliorates endothelial dysfunction and impaired angiogenesis via the Nrf2/PPARγ/sFlt-1 axis in preeclampsia.

Preeclampsia is a severe complication of pregnancy characterised by variable degrees of placental malperfusion. A growing body of evidence indicates that soluble endoglin and soluble fms-like tyrosine kinase-1 (sFlt-1) play important pathophysiological roles in preeclampsia, causing endothelial dysfunction, hypertension, and multiorgan injury. A drug that is safe in pregnancy and inhibits placental sFlt-1 and soluble endoglin secretion would be an attractive treatment strategy for preeclampsia. Procyanidin B2, a bioactive food compound, has been reported to exert multiple beneficial functions. Placental explant cultures in vitro are useful for studying tissue functions including release of secretory components, pharmacology, toxicology, and disease processes. The reduced uterine perfusion pressure (RUPP) rat model has been widely used as a model of preeclampsia. We aimed to investigate the effect of procyanidin B2 on preeclampsia via using placental explant cultures and RUPP rat model. In this study, we demonstrated that procyanidin B2 reduced soluble endoglin and sFlt-1 secretion from human umbilical vein endothelial cells (HUVECs), primary trophoblasts, and placental explants from preeclamptic pregnancies. Moreover, procyanidin B2 alleviated endothelial dysfunction and impaired angiogenesis induced by sFlt-1, including increasing the migration, invasion and angiogenesis of endothelial cells and decreasing the expression of vascular cell adhesion molecule-1 (VCAM-1) and leukocyte adhesion on HUVECs. In addition, procyanidin B2 promoted nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear accumulation and induced peroxisome proliferator-activated receptor γ (PPARγ) expression in primary placental tissues and endothelial cells. Importantly, Nrf2 specifically binds to the PPARγ promoter region (-1227/-1217) and enhances its transcriptional activity. Procyanidin B2 inhibits sFlt-1 secretion via the Nrf2/PPARγ axis. In the RUPP rat model of preeclampsia, procyanidin B2 attenuated RUPP-induced maternal angiogenic imbalance, hypertension and improved placental and foetal weight. Taken together, our results demonstrate that procyanidin B2 inhibits sFlt-1 secretion and ameliorates endothelial dysfunction and impaired angiogenesis via the Nrf2/PPARγ axis in preeclampsia. Procyanidin B2 may be a novel therapeutic agent for treatment of preeclampsia.

Membrane and soluble endoglin role in cardiovascular and metabolic disorders related to metabolic syndrome.

Membrane endoglin (Eng, CD105) is a transmembrane glycoprotein essential for the proper function of vascular endothelium. It might be cleaved by matrix metalloproteinases to form soluble endoglin (sEng), which is released into the circulation. Metabolic syndrome comprises conditions/symptoms that usually coincide (endothelial dysfunction, arterial hypertension, hyperglycemia, obesity-related insulin resistance, and hypercholesterolemia), and are considered risk factors for cardiometabolic disorders such as atherosclerosis, type II diabetes mellitus, and liver disorders. The purpose of this review is to highlight current knowledge about the role of Eng and sEng in the disorders mentioned above, in vivo and in vitro extent, where we can find a wide range of contradictory results. We propose that reduced Eng expression is a hallmark of endothelial dysfunction development in chronic pathologies related to metabolic syndrome. Eng expression is also essential for leukocyte transmigration and acute inflammation, suggesting that Eng is crucial for the regulation of endothelial function during the acute phase of vascular defense reaction to harmful conditions. sEng was shown to be a circulating biomarker of preeclampsia, and we propose that it might be a biomarker of metabolic syndrome-related symptoms and pathologies, including hypercholesterolemia, hyperglycemia, arterial hypertension, and diabetes mellitus as well, despite the fact that some contradictory findings have been reported. Besides, sEng can participate in the development of endothelial dysfunction and promote the development of arterial hypertension, suggesting that high levels of sEng promote metabolic syndrome symptoms and complications. Therefore, we suggest that the treatment of metabolic syndrome should take into account the importance of Eng in the endothelial function and levels of sEng as a biomarker and risk factor of related pathologies.

Role of soluble endoglin in BMP9 signaling.

Endoglin (ENG) is a coreceptor of the transforming growth factor-ß (TGFß) family signaling complex, which is highly expressed on endothelial cells and plays a key role in angiogenesis. Its extracellular domain can be cleaved and released into the circulation as soluble ENG (sENG). High circulating levels of sENG contribute to the pathogenesis of preeclampsia (PE). Circulating bone morphogenetic protein 9 (BMP9), a vascular quiescence and endothelial-protective factor, binds sENG with high affinity, but how sENG participates in BMP9 signaling complexes is not fully resolved. sENG was thought to be a ligand trap for BMP9, preventing type II receptor binding and BMP9 signaling. Here we show that, despite cell-surface ENG being a dimer linked by disulfide bonds, sENG purified from human placenta and plasma from PE patients is primarily in a monomeric form. Incubating monomeric sENG with the circulating form of BMP9 (prodomain-bound form) in solution leads to the release of the prodomain and formation of a sENG:BMP9 complex. Furthermore, we demonstrate that binding of sENG to BMP9 does not inhibit BMP9 signaling. Indeed, the sENG:BMP9 complex signals with comparable potency and specificity to BMP9 on human primary endothelial cells. The full signaling activity of the sENG:BMP9 complex required transmembrane ENG. This study confirms that rather than being an inhibitory ligand trap, increased circulating sENG might preferentially direct BMP9 signaling via cell-surface ENG at the endothelium. This is important for understanding the role of sENG in the pathobiology of PE and other cardiovascular diseases.

Soluble Endoglin Stimulates Inflammatory and Angiogenic Responses in Microglia That Are Associated with Endothelial Dysfunction.

Increased soluble endoglin (sENG) has been observed in human brain arteriovenous malformations (bAVMs). In addition, the overexpression of sENG in concurrence with vascular endothelial growth factor (VEGF)-A has been shown to induce dysplastic vessel formation in mouse brains. However, the underlying mechanism of sENG-induced vascular malformations is not clear. The evidence suggests the role of sENG as a pro-inflammatory modulator, and increased microglial accumulation and inflammation have been observed in bAVMs. Therefore, we hypothesized that microglia mediate sENG-induced inflammation and endothelial cell (EC) dysfunction in bAVMs. In this study, we confirmed that the presence of sENG along with VEGF-A overexpression induced dysplastic vessel formation. Remarkably, we observed increased microglial activation around dysplastic vessels with the expression of NLRP3, an inflammasome marker. We found that sENG increased the gene expression of VEGF-A, pro-inflammatory cytokines/inflammasome mediators (TNF-α, IL-6, NLRP3, ASC, Caspase-1, and IL-1ß), and proteolytic enzyme (MMP-9) in BV2 microglia. The conditioned media from sENG-treated BV2 (BV2-sENG-CM) significantly increased levels of angiogenic factors (Notch-1 and TGFß) and pERK1/2 in ECs but it decreased the level of IL-17RD, an anti-angiogenic mediator. Finally, the BV2-sENG-CM significantly increased EC migration and tube formation. Together, our study demonstrates that sENG provokes microglia to express angiogenic/inflammatory molecules which may be involved in EC dysfunction. Our study corroborates the contribution of microglia to the pathology of sENG-associated vascular malformations.

Regulation and Release of Vasoactive Endoglin by Brain Endothelium in Response to Hypoxia/Reoxygenation in Stroke.

In large vessel occlusion stroke, recanalization to restore cerebral perfusion is essential but not necessarily sufficient for a favorable outcome. Paradoxically, in some patients, reperfusion carries the risk of increased tissue damage and cerebral hemorrhage. Experimental and clinical data suggest that endothelial cells, representing the interface for detrimental platelet and leukocyte responses, likely play a crucial role in the phenomenon referred to as ischemia/reperfusion (I/R)-injury, but the mechanisms are unknown. We aimed to determine the role of endoglin in cerebral I/R-injury; endoglin is a membrane-bound protein abundantly expressed by endothelial cells that has previously been shown to be involved in the maintenance of vascular homeostasis. We investigated the expression of membranous endoglin (using Western blotting and RT-PCR) and the generation of soluble endoglin (using an enzyme-linked immunosorbent assay of cell culture supernatants) after hypoxia and subsequent reoxygenation in human non-immortalized brain endothelial cells. To validate these in vitro data, we additionally examined endoglin expression in an intraluminal monofilament model of permanent and transient middle cerebral artery occlusion in mice. Subsequently, the effects of recombinant human soluble endoglin were assessed by label-free impedance-based measurement of endothelial monolayer integrity (using the xCELLigence DP system) and immunocytochemistry. Endoglin expression is highly inducible by hypoxia in human brain endothelial monolayers in vitro, and subsequent reoxygenation induced its shedding. These findings were corroborated in mice during MCAO; an upregulation of endoglin was displayed in the infarcted hemispheres under occlusion, whereas endoglin expression was significantly diminished after transient MCAO, which is indicative of shedding. Of note is the finding that soluble endoglin induced an inflammatory phenotype in endothelial monolayers. The treatment of HBMEC with endoglin resulted in a decrease in transendothelial resistance and the downregulation of VE-cadherin. Our data establish a novel mechanism in which hypoxia triggers the initial endothelial upregulation of endoglin and subsequent reoxygenation triggers its release as a vasoactive mediator that, when rinsed into adjacent vascular beds after recanalization, can contribute to cerebral reperfusion injury.

Paeoniflorin alleviates endothelial dysfunction caused by overexpression of soluble fms-like tyrosine kinase 1 and soluble endoglin in preeclampsia via VEGFA upregulation.

This study assessed the protective effects of paeoniflorin against preeclampsia-related endothelial damage (ED). Human umbilical vein endothelial cells (HUVECs) isolated from healthy puerperae were identified by immunofluorescence assay. After paeoniflorin treatment, HUVECs were induced by soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng) to establish ED. Cell viability, migration, invasion, tube formation, and apoptosis were assessed by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium MTT assay, Scratch assay, Transwell assay, tube formation assay, and flow cytometry. VEGFA expression in HUVECs was analyzed by Western blot. HUVECs were successfully isolated and identified as Von Willebrand factor (vWF) positive. Individual treatment or cotreatment of sFlt-1 and sEng inhibited migration, invasion and tube formation, enhanced apoptosis, and decreased VEGFA expression in HUVECs. Paeoniflorin pretreatment partially reversed the effects delivered by cotreatment of sFlt-1 and sEng in HUVECs. Paeoniflorin alleviated preeclampsia-related ED caused by overexpression of sFlt-1 and sEng by upregulating VEGFA.

Soluble Endoglin and Uterine Artery Flow Doppler Ultrasonography as Markers of Progression to Preeclampsia in Women with Gestational Hypertension.

INTRODUCTION: Gestational hypertension (GH) pregnancies are at a high risk of developing adverse outcomes, including progression to preeclampsia. Prediction of GH-related adverse outcomes is challenging because there are no available clinical tests that may predict their occurrence. OBJECTIVE: The aim of the study was to determine the clinical usefulness of the soluble endoglin (sEng) and parameters of uterine artery flow (UtAF) measured by Doppler ultrasonography as markers of progression to preeclampsia in women with GH. SETTING: Mexico City, Mexico. MATERIAL AND METHODS: We included 77 singleton pregnant women with GH in a nested case-control study. Cases were women who progressed to preeclampsia (n = 36), and controls were those who did not (n = 41). Serum sEng and UtAF measurements were performed at enrollment. The main outcomes measured were progression to preeclampsia and occurrence of preterm delivery (PD) <37 and <34 weeks of gestation, small for gestational age infant (SGA), and fetal growth restriction (FGR). RESULTS: Women with sEng values in the highest tertile had higher risk of progression to preeclampsia, preterm delivery <34 weeks of gestation, and fetal growth restriction, odds ratios (ORs) ≥3.7. Patients with abnormal UtAF Dopp-ler-pulsatility index had higher risk of progression to preeclampsia, preterm delivery <34 weeks of gestation, small for gestational age infant, and fetal growth restriction (ORs ≥3.3). The presence of notch was associated with higher risk of progression to preeclampsia, preterm delivery <37 and <34 weeks of gestation, SGA infant, and fetal growth restriction (ORs ≥2.9). However, logistic regression analysis revealed that only serum sEng was a significant and independent risk factor for progression of GH to preeclampsia, preterm delivery <34 weeks of gestation, and fetal growth restriction (ORs ≥3.1). CONCLUSIONS: In GH pregnancies, UtAF Doppler ultrasonography is associated with increased risk of adverse outcomes and progression to preeclampsia. However, serum sEng concentration appears to be a better predictor to assess the risk of adverse maternal and perinatal outcomes and progression to preeclampsia.

Low placental growth factor levels and high soluble endoglin levels at 26-31 weeks of gestation precede light placenta with and without relatively heavy infant, respectively: A retrospective cohort study.

AIM: Our aim was to examine whether serum levels of placental growth factor (PlGF) and soluble endoglin (sEng) at 19-25 and 26-31 weeks of gestation were associated with the occurrence of the 9-block categorization of placenta weight (PW) and fetal/placenta ratio (F/P ratio). METHODS: We performed a retrospective cohort study in 1391 women with singleton pregnancy. Serum levels of PlGF and sEng were measured by enzyme immunosorbent assay. A light placenta was defined as PW ZS < -1.28 SD. Based on the PW (light, normal, and heavy) and F/P ratio (relatively heavy, balanced growth, and relatively small), 9-block categorization were performed. Multivariable logistic regression analyses were performed. RESULTS: Low PlGF at 26-31 weeks was an independent risk factor for the birth of infants belonging to Block A (light placenta and relatively heavy infant), after adjusting for prepregnancy body mass index and serum levels of sEng. High sEng at 26-31 weeks was an independent risk factor for the birth of infants belonging to Block D (light placenta and balanced growth of infant), after adjusting for past history of either preeclampsia or gestational hypertension, high pulsatility index of uterine artery flow velocity waveforms in the second trimester, and serum level of PlGF. CONCLUSIONS: Low PlGF levels at 26-31 weeks of gestation may precede a light placenta and relatively heavy infant (Block A), and high sEng levels at 26-31 weeks of gestation may precede a light placenta and balanced growth of infant (Block D).

Generation of a Soluble Form of Human Endoglin Fused to Green Fluorescent Protein.

Endoglin (Eng, CD105) is a type I membrane glycoprotein that functions in endothelial cells as an auxiliary receptor for transforming growth factor ß (TGF-ß)/bone morphogenetic protein (BMP) family members and as an integrin ligand, modulating the vascular pathophysiology. Besides the membrane-bound endoglin, there is a soluble form of endoglin (sEng) that can be generated by the action of the matrix metalloproteinase (MMP)-14 or -12 on the juxtamembrane region of its ectodomain. High levels of sEng have been reported in patients with preeclampsia, hypercholesterolemia, atherosclerosis and cancer. In addition, sEng is a marker of cardiovascular damage in patients with hypertension and diabetes, plays a pathogenic role in preeclampsia, and inhibits angiogenesis and tumor proliferation, migration, and invasion in cancer. However, the mechanisms of action of sEng have not yet been elucidated, and new tools and experimental approaches are necessary to advance in this field. To this end, we aimed to obtain a fluorescent form of sEng as a new tool for biological imaging. Thus, we cloned the extracellular domain of endoglin in the pEGFP-N1 plasmid to generate a fusion protein with green fluorescent protein (GFP), giving rise to pEGFP-N1/Eng.EC. The recombinant fusion protein was characterized by transient and stable transfections in CHO-K1 cells using fluorescence microscopy, SDS-PAGE, immunodetection, and ELISA techniques. Upon transfection with pEGFP-N1/Eng.EC, fluorescence was readily detected in cells, indicating that the GFP contained in the recombinant protein was properly folded into the cytosol. Furthermore, as evidenced by Western blot analysis, the secreted fusion protein yielded the expected molecular mass and displayed a specific fluorescent signal. The fusion protein was also able to bind to BMP9 and BMP10 in vitro. Therefore, the construct described here could be used as a tool for functional in vitro studies of the extracellular domain of endoglin.

Follistatin and Soluble Endoglin Predict 1-Year Nonrelapse Mortality after Allogeneic Hematopoietic Cell Transplantation.

Damage-associated angiogenic factors (AFs), including follistatin (FS) and soluble endoglin (sEng), are elevated in circulation at the onset of acute graft-versus-host disease (GVHD). We hypothesized that regimen-related tissue injury also might be associated with aberrant AF levels and sought to determine the relevance of these AF on nonrelapse mortality (NRM) in patients with acute GVHD and those without acute GVHD. To test our hypothesis, we analyzed circulating levels of FS, sEng, angiopoietin-2 (Ang2), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) A and B, placental growth factor (PlGF), and soluble VEGF receptor (sVEGFR)-1 and -2, in plasma samples from patients enrolled on Blood and Marrow Transplant Clinical Trials Network (BMT CTN) 0402 (n = 221), which tested GVHD prophylaxis after myeloablative hematopoietic stem cell transplantation (HCT). We found that the interaction between FS and sEng had an additive effect in their association with 1-year NRM. In multivariate analysis, patients with the highest levels of day +28 FS and sEng had a 14.9-fold greater hazard ratio (HR) of NRM (95% confidence interval, 3.2 to 69.4; P < .01) when compared with low levels of FS and sEng. We validated these findings using an external cohort of patients (n = 106). Pre-HCT measurements of FS and sEng were not associated with NRM, suggesting that elevations in these factors early post-HCT may be consequences of early regimen-related toxicity. Determining the mechanisms responsible for patient-specific vulnerability to treatment toxicities and endothelial damage associated with specific AF elevation may guide interventions to reduce NRM post-HCT.

The diagnosis values of serum STAT4 and sEng in preeclampsia.

OBJECTIVE: To detect the levels of signal transducer and activator of transcription 4 (STAT4) and soluble endoglin (sEng) in preeclampsia patients and analyze the diagnostic values of STAT4 and sEng in preeclampsia. METHODS: Fifty-four pregnant women with preeclampsia from October 2017 to June 2018 were included in this study. Twenty-eight matched healthy pregnant women were set as the control group. The general clinical characteristics were measured. Serum STAT4 and sEng were detected by ELISA. Correlation between STAT4 and sEng, and their diagnostic value in preeclampsia were analyzed. RESULTS: Compared with control, the prothrombin time in preeclampsia was significantly lower, while the mean arterial pressure, 24-hour urine protein, serum creatinine, fibrinogen, and ALT were significantly higher. The circulating levels of STAT4 and sEng were significantly increased in the preeclampsia. The serum levels of STAT4 and sEng in preeclampsia were positively correlated. For the diagnosis of preeclampsia by the serum STAT4, AUC is 0.902, and the sensitivity and specificity are 0.893 and 0.929. By the serum sEng, AUC is 0.873, and the sensitivity and specificity are 0.816 and 0.905. CONCLUSION: The serum levels of STAT4 and sEng were significantly increased in preeclampsia with disease severity status, which have promise as diagnostic markers in preeclampsia.

Endoglin (CD105) and VEGF as potential angiogenic and dissemination markers for colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is an important current problem concerning public health due to its high incidence and mortality. Advances in molecular and cellular knowledge and the detection of new disease biomarkers are very important to improve prognosis, prediction, and early diagnosis. In this study, we aimed to analyze the gene and protein expression levels of two angiogenic markers, VEGF and soluble Endoglin, during different tumor stages as well as at different stages of cancer treatment, to predict the diagnosis and evolution of colon and rectal cancer. MATERIAL AND METHODS: This study includes 133 CRC patients (93 with colon cancer and 40 with rectal cancer) on which the gene and protein expression of Endoglin (membrane and soluble form) and VEGF were analyzed by molecular and immunohistochemical techniques on different tumor stage samples and plasma obtained preoperatively as well as 3, 6, and 9 months after resection of the tumor. RESULTS: VEGF and Endoglin gene expressions were higher in tumor tissue than in surrounding non-tumoral tissue for both types of cancer. The VEGF levels in plasma were found to decrease in less aggressive tumors, whereas soluble Endoglin was increased in preoperative samples of patients with metastasis. Membrane Endoglin expression was higher on the vascular endothelium of more aggressive tumors. In contrast, Endoglin expression was mainly in the colon epithelium in less aggressive stage tumors. CONCLUSION: Endoglin and VEGF are proteins with a major role in the tumor angiogenesis process. This study performed with a wide cohort of human samples shows that both proteins seem to be valuable biomarkers in the diagnosis and prognosis of CRC.

Pregnancy-Induced High Plasma Levels of Soluble Endoglin in Mice Lead to Preeclampsia Symptoms and Placental Abnormalities.

Preeclampsia is a pregnancy-specific disease of high prevalence characterized by the onset of hypertension, among other maternal or fetal signs. Its etiopathogenesis remains elusive, but it is widely accepted that abnormal placentation results in the release of soluble factors that cause the clinical manifestations of the disease. An increased level of soluble endoglin (sEng) in plasma has been proposed to be an early diagnostic and prognostic biomarker of this disease. A pathogenic function of sEng involving hypertension has also been reported in several animal models with high levels of plasma sEng not directly dependent on pregnancy. The aim of this work was to study the functional effect of high plasma levels of sEng in the pathophysiology of preeclampsia in a model of pregnant mice, in which the levels of sEng in the maternal blood during pregnancy replicate the conditions of human preeclampsia. Our results show that wild type pregnant mice carrying human sEng-expressing transgenic fetuses (fWT(hsEng+)) present high plasma levels of sEng with a timing profile similar to that of human preeclampsia. High plasma levels of human sEng (hsEng) are associated with hypertension, proteinuria, fetal growth restriction, and the release of soluble factors to maternal plasma. In addition, fWT(hsEng+) mice also present placental alterations comparable to those caused by the poor remodeling of the spiral arteries characteristic of preeclampsia. In vitro and ex vivo experiments, performed in a human trophoblast cell line and human placental explants, show that sEng interferes with trophoblast invasion and the associated pseudovasculogenesis, a process by which cytotrophoblasts switch from an epithelial to an endothelial phenotype, both events being related to remodeling of the spiral arteries. Our findings provide a novel and useful animal model for future research in preeclampsia and reveal a much more relevant role of sEng in preeclampsia than initially proposed.