sFlt-1 and soluble endoglin concentrations in serum vs plasma in preterm preeclampsia: Are they interchangeable for biomarker studies?

An endogenous inhibitor of angiogenesis downregulated by hypoxia in human aortic valve stenosis promotes disease pathogenesis

Aortic valve stenosis is the most common valve disease in the western world. Central to the pathogenesis of this disease is the growth of new blood vessels (angiogenesis) within the aortic valve allowing infiltration of immune cells and development of intra-valve inflammation. Identifying the cellular mediators involved in this angiogenesis is important as this may reveal new therapeutic targets which could ultimately prevent the progression of aortic valve stenosis. Aortic valves from patients undergoing surgery for aortic valve replacement or dilation of the aortic arch were examined both ex vivo and in vitro. We now demonstrate that the anti-angiogenic protein, soluble fms-like tyrosine kinase 1 (sFlt1), a non-signalling soluble receptor for vascular endothelial growth factor, is constitutively expressed in non-diseased valves. sFlt-1 expression was, however, significantly reduced in aortic valve tissue from patients with aortic valve stenosis while protein markers of hypoxia were simultaneously increased. Exposure of primary-cultured valve interstitial cells to hypoxia resulted in a decrease in the expression of sFlt-1. We further reveal using a bioassay that siRNA knock-down of sFlt1 in valve interstitial cells directly results in a pro-angiogenic environment. Finally, incubation of aortic valves with sphingosine 1-phosphate, a bioactive lipid-mediator, increased sFlt-1 expression and inhibited angiogenesis within valve tissue. In conclusion, this study demonstrates that sFlt1 expression is directly correlated with angiogenesis in aortic valves and the observed decrease in sFlt-1 expression in aortic valve stenosis could increase valve inflammation, promoting disease progression. This could be a viable therapeutic target in treating this disease.

Decidual mesenchymal stem/stromal cells from preeclamptic patients secrete endoglin, which at high levels inhibits endothelial cell attachment invitro

INTRODUCTION

In preeclampsia (PE), inadequate remodelling of spiral arterioles in the decidua basalis causes oxidative stress and subsequent increased release of antiangiogenic soluble endoglin (sENG) into the maternal circulation. Decidual mesenchymal stem/stromal cells (DMSCs) reside adjacent to endothelial cells in this vascular niche. Surprisingly, DMSCs express membrane-bound ENG (CD105). PE-affected DMSCs (PE-DMSCs) are abnormal and due to reduced extravillous invasion, more of them are present, but the significance of this is not known.

METHODS

DMSCs were isolated and characterised from normotensive control and severe-PE placentae. Extracellular vesicle (EV) types, shed microvesicles (sMV) and exosomes, were isolated from DMSC conditioned media (DMSC_CM), respectively. Secretion of ENG by DMSCs was assessed by ELISA of DMSC_CM, with and without EV depletion. The effects of reducing ENG concentration, by blocking antibody, on human umbilical vein endothelial cell (HUVEC) attachment were assessed by xCELLigence real-time functional assays.

RESULTS

ENG was detected in DMSC_CM and these levels significantly decreased when depleted of exosomes and sMV. There was no significant difference in the amount of ENG secreted by control DMSCs and PE-DMSCs. Blocking ENG in concentrated DMSC_CM, used to treat HUVECs, improved endothelial cell attachment.

DISCUSSION

In normotensive pregnancies, DMSC secretion of ENG likely has a beneficial effect on endothelial cells. However, in PE pregnancies, shallow invasion of the spiral arterioles exposes more PE-DMSC derived sources of ENG (soluble and EV). The presence of these PE-DMSCs in the vascular niche contributes to endothelial cell dysfunction.

Assessing the Role of Uric Acid as a Predictor of Preeclampsia

We assessed the diagnostic utility of uric acid for the prediction of preeclampsia. An observational prospective approach was carried out during 2014. Preeclamptic women were classified into 4 groups accordingly to the onset of preeclampsia and the presence of intrauterine growth restriction (IUGR). Serum uric acid levels, urea, and creatinine were measured. Receiver operating curves (ROC) of the uric acid levels ratio (UAr) between a dosage before and after the 20th week of gestation were performed. One thousand two hundred and ninety-third pregnant women were enrolled in this study. Eight hundred ten had non-complicated pregnancies, 40 preeclampsia, 33 gestational hypertension, and 20 IUGR without preeclampsia. Uric acid significantly raised after 20 weeks of gestation in women who develop preeclampsia before 34 weeks (Group A) or in those who develop preeclampsia after 37 weeks associated with IUGR (Group C). In women who develop preeclampsia after 34 weeks without IUGR (Groups B and D), uric acid increased after the 30th week of gestation. In all groups, UAr was greater than 1.5. In gestational hypertension, UAr was superior to 1.5 toward the end of gestation, while in IUGR without preeclampsia, the behavior of serum uric acid was similar to non-complicated pregnancies. In all cases, urea and creatinine showed normal values, confirming that patients had no renal compromise. ROC area was 0.918 [95% confidence interval (CI): 0.858–0.979) for the preeclampsia group and 0.955 (95% CI: 0.908–1.000) for Group A. UAr at a cut-off point ≥1.5 had a very low positive predictive value, but a high negative predictive value of 99.5% for preeclampsia and it reached 100% for Group A. Thus, a UAr less than 1.5 may be a helpful parameter with a strong exclusion value and high sensitivity for those women who are not expected to develop preeclampsia. Additionally, this low-cost test would allow for better use of resources in developing countries.

Soluble endoglin in urine as an early-pregnancy preeclampsia marker: antenatal longitudinal feasibility study

This study aimed to evaluate soluble endoglin (sEng) in urine as a preeclampsia predictor. Ninety-three pregnant women at risk for preeclampsia were followed. Spot urine sample ELISA analysis before 20 weeks of gestation was done to assess protein levels. Logistic regression analysis evaluated associations between preeclampsia with sEng/creatinine ratio, pg/mg, adjusted for risk factors. Preeclampsia incidence was 22.8% (20/92). Urinary sEng/creatinine (pg/mg) 0.001 (95% CI 0.001-0.136) was associated, adjusted for body mass index > 28 kg/m² OR 6.44 (95% CI 1.11-37.47) and mean arterial pressure OR 1.20 (1.07-1.35). During the first half of gestation sEng urinary excretion was lower in pregnant women developing preeclampsia.Impact statementWhat is already known on this subject? The angiogenesis factors present in the plasma of pregnant women have shown good preclinical predictors of preeclampsia. Studies on urinary markers in pregnancy are infrequent, despite the ease of obtaining urine specimens.What do the results of this study add? Values of the sEng/creatinine ratio during the first half of pregnancy were related to a higher chance of preeclampsia occurring when it was evaluated alone or adjusted by body mass index and mean arterial pressure values.What are the implications of these findings for clinical practice and/or further research? The potential benefits of a urinary test compared to one of the blood levels include its non-invasive nature and ease of performing the test, even during prenatal care. Future research is expected to evaluate the sEng/creatinine ratio relevance to improve clinical scores of preeclampsia prediction for the identification of women at risk for this disease.

Decidual mesenchymal stem/stromal cell-derived extracellular vesicles ameliorate endothelial cell proliferation, inflammation, and oxidative stress in a cell culture model of preeclampsia

Oxidative stress and endothelial dysfunction contribute substantially to the pathogenesis of preeclampsia (PE). Decidual mesenchymal stem/stromal cells (DMSC), reportedly reduce endothelial cell dysfunction and alleviate PE-like symptoms in a murine model. However, as a therapeutic strategy, the use of whole DMSC presents significant technical limitations, which may be overcome by employing DMSC-secreted extracellular vesicles (DMSC_EV). DMSC_EV restoration of endothelial dysfunction through a paracrine effect may alleviate the clinical features of PE.

OBJECTIVE

To determine whether DMSC-secreted, extracellular vesicles (DMSC_EV) restore endothelial cell function and reduce oxidative stress.

METHODS

DMSC were isolated from the placentae of uncomplicated term pregnancies and DMSC_EV prepared by ultracentrifugation. Human umbilical vein endothelial cells (HUVEC) were treated with bacterial lipopolysaccharide (LPS), or with serum from PE patients, to model the effects of PE. DMSC_EV were then added to treated HUVEC and their growth profiles, inflammatory state, and oxidative stress levels measured.

RESULTS

DMSC_EV displayed characteristic features of extracellular vesicles. In both LPS- and PE serum-treatment models, addition of DMSC_EV significantly increased HUVEC cell attachment and proliferation, and significantly reduced production of pro-inflammatory cytokine IL-6. The addition of DMSC_EV to LPS-treated HUVEC had no significant effect on total antioxidant capacity, superoxide dismutase levels or on lipid peroxidation levels. In contrast, the addition of DMSC_EV to PE serum-treated HUVEC resulted in a significant reduction in levels of lipid peroxidation.

CONCLUSION

Addition of DMSC_EV had beneficial effects in both LPS- and PE serum- treated HUVEC but the two treatment models to induce endothelial cell dysfunction showed differences. The LPS treatment of HUVEC model may not accurately model the endothelial cell dysfunction characteristic of PE. Human cell culture models of PE show that DMSC_EV improve endothelial cell dysfunction in PE, but testing in in vivo models of PE is required.

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.

Optimizing Measurement of Vascular Endothelial Growth Factor in Small Blood Samples of Premature Infants

To establish a method that allows for the reliable assessment of vascular endothelial growth factor (VEGF-A) concentrations in very small blood samples of preterm infants. Systemic VEGF measurements are important in view of the most appropriate Anti-VEGF drug to be used for the treatment of acute retinopathy of prematurity (ROP). Cord blood samples from preterm (n = 6) infants, blood samples from preterm infants with treatment requiring ROP (n = 12), and blood samples from healthy adults (n = 10) were collected. Serum, citrate plasma, and serum from recalcified citrate blood were obtained. Levels of VEGF-A and platelet factor-4 (PF-4) were quantified by ELISA or AlphaLISA immunoassay. VEGF-A levels could be detected by both assays, with the AlphaLISA generating slightly lower levels in healthy adults, but not in cord blood of preterm infants. In plasma samples, VEGF levels ranged from non detectable to 181 pg/ml. PF-4 concentrations were between 0.16–3.88 µg/ml. Values of VEGF-A and PF-4 in serum and recalcified serum were significantly higher compared to plasma through the release of these cytokines after platelet activation. In plasma samples of infants with ROP, VEGF-A could always be detected and its values ranged from 19.50 to 245.91 pg/ml and PF-4 concentrations were between 0.1 and 3.3 µg/ml. Using the AlphaLISA kit, we were able to detect VEGF in small sample volumes (5 µl plasma or serum/well) in premature infants with treatment requiring ROP and to monitor platelet activation by PF-4 detection. Minimal blood probe volumes reduce phlebotomy losses avoiding the risk of iatrogenic anemia, thus allowing close monitoring of the cytokine levels in these very fragile infants.