Fetal Endothelial Function Research Articles

FABP4 as potential indicator for GDM-induced fetal endothelial dysfunction

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): DFG project no. 288034826—International Research Training Group (IRTG) 2251 Background Gestational diabetes mellitus (GDM) is linked to an elevated risk of developing cardiovascular diseases (CVD) both for the mother and the baby in later life. Previous studies have identified fatty acid-binding protein 4 (FABP4) as a prime candidate involved in the pathophysiology of GDM. FABP4 is known to promote an inflammatory response and vascular permeability, induce oxidative stress in endothelial cells (ECs), and impair the nitric oxide signaling pathway, thereby promoting endothelial dysfunction. Indeed, women with GDM exhibit elevated blood levels of FABP4, suggesting its potential as a biomarker for endothelial dysfunction and cardiovascular risk assessment in GDM. However, the role that FABP4 plays in the fetal endothelial function remains poorly understood. Purpose Thus, our aim is to understand the role of FABP4 in fetal endothelial dysfunction and its regulation to mitigate the impact of GDM on the vasculature. Methods Fetoplacental vessels and primary human umbilical vein endothelial cells (HUVECs) were isolated from placentas and umbilical cords obtained from both normoglycemic (NG) and GDM pregnancies. We also obtained the clinical data from the mothers and collected the cord blood. Total mRNA from HUVECs was used for bulk RNA sequencing to compare gene expression, while gene expression analysis in the vessels was conducted using RT-qPCR. Additionally, NG HUVECs were pooled and cultured under high laminar flow conditions (30 dyn/cm²) or subjected to various treatments, including insulin (5nM), glucose (25mM), simvastatin (10nm), or VEGF-A stimulation. Subsequent RT-qPCRs were performed to analyze the gene expression of several genes of interest. Results The bulk RNA sequencing data analysis revealed FABP4 as an overexpressed gene in GDM HUVECs compared to NG. Furthermore, the analysis of data through Gene Set Enrichment Analysis provided a list of different gene sets that are enriched in GDM samples. Among these gene sets are pathways or processes implicated in endothelial dysfunction, such as angiogenesis, PI3K/AKT/mTOR signaling, reactive oxygen species pathway, or inflammatory response. In vitro experiments provided evidence for an elevated FABP4 mRNA expression after VEGF treatment of HUVECs. Conversely, both simvastatin treatment and exposure to laminar flow reduced FABP4 mRNA expression and increased eNOS expression, suggesting a potential inhibitory effect of nitric oxide on FABP4. Conclusion We provided evidence that FABP4 could be involved in fetal GDM-induced endothelial dysfunction. Shear stress and statins might protect the endothelium against the negative impact of FABP4.

Higher gestational weight gain delays wound healing and reduces expression of long non-coding RNA KLRK1-AS1 in neonatal endothelial progenitor cells.

High gestational weight gain (GWG) is a cardiovascular risk factor and may disturb neonatal endothelial function. Long non-coding RNAs (lncRNAs) regulate gene expression epigenetically and can modulate endothelial function. Endothelial colony forming cells (ECFCs), circulating endothelial precursors, are a recruitable source of endothelial cells and sustain endothelial function, vascular growth and repair. We here investigated whether higher GWG affects neonatal ECFC function and elucidated the role of lncRNAs herein. Wound healing of umbilical cord blood-derived ECFCs after pregnancies with GWG <13 kg versus >13kg was determined in a scratch assay and based on monolayer impedance after electric wounding (electric cell-substrate impedance sensing, ECIS). LncRNA expression was analysed by RNA sequencing. The function of killer cell lectin-like receptor K1 antisense RNA (KLRK1-AS1) was investigated after siRNA-based knockdown. Closure of the scratch was delayed by 25% (P=0.041) in the higher GWG group and correlated inversely with GWG (R=-0.538, P=0.012) in all subjects (n=22). Similarly, recovery of the monolayer barrier after electric wounding was delayed (-11% after 20h; P=0.014; n=15). Several lncRNAs correlated with maternal GWG, the most significant one being KLRK1-AS1 (log2 fold change=-0.135, P<0.001, n=35). KLRK1-AS1 knockdown (n=4) reduced barrier recovery after electric wounding by 21% (P=0.029) and KLRK1-AS1 expression correlated with the time required for wound healing for both scratch (R=0.447, P=0.033) and impedance-based assay (R=0.629, P=0.014). Higher GWG reduces wound healing of neonatal ECFCs, and lower levels of the lncRNA KLRK1-AS1may underlie this. KEY POINTS: Maternal cardiovascular risk factors such as diabetes, obesity and smoking in pregnancy disturb fetal endothelial function, and we here investigated whether also high gestational weight gain (GWG) has an impact on fetal endothelial cells. Circulating endothelial progenitor cells (endothelial colony forming cells, ECFCs) are highly abundant in the neonatal blood stream and serve as a circulating pool for vascular growth and repair. We revealed that higher GWG delays wound healing capacity of ECFCs in vitro. We identified the regulatory RNA lncRNA KLRK1-AS1 as a link between GWG and delayed ECFC wound healing. Our data show that high GWG, independent of pre-pregnancy BMI, affects neonatal ECFC function.

Fetal sex and maternal fasting glucose affect neonatal cord blood-derived endothelial progenitor cells

BackgroundMaternal cardiovascular risk factors (CVRF) in pregnancy, i.e., obesity and hyperglycemia, transmit to the fetus and affect placental and fetal endothelial function. Moreover, a sex dimorphism in endothelial function and susceptibility towards CVRF exists already in utero. Endothelial colony-forming cells (ECFC) are circulating endothelial progenitors highly present in neonatal cord blood and sensitive to CVRF. This study investigated whether fetal sex or subtle maternal metabolic changes within healthy range alter fetal ECFC outgrowth.MethodsOutgrowth of ECFC from cord blood of male (n = 31) and female (n = 26) neonates was analyzed after healthy pregnancies and related to fetal sex and maternal metabolic parameters.ResultsMale ECFC grew out earlier (−20.57% days; p = 0.031) than female. Although all women were non-diabetic, higher levels of fasting plasma glucose (FPG) at midpregnancy increased the time required for colony outgrowth (OR: 1.019; p = 0.030), which, after stratifying for fetal sex, was significant only in the males. Gestational weight gain and BMI did not affect outgrowth. Colony number was unchanged by all parameters.ConclusionsFetal sex and maternal FPG within normal range alter ECFC function in utero. A role of ECFC in postnatal angiogenesis and vasculogenesis has been suggested, which may be affected by altered outgrowth dynamics.ImpactThis study is the first to report that a sexual dimorphism exists in ECFC function, as cells of female progeny require a longer period of time until colony outgrowth than ECFC of male progeny.Our data show that ECFC function is highly sensitive and affected by maternal glucose levels even in a normal, non-diabetic range.Our data raise the question of whether maternal plasma glucose in pregnancy should be considered to play a critical role even in the non-diabetic setting.

Non-Invasive Detection of Fetal Vascular Endothelial Function in Gestational Diabetes Mellitus.

ObjectivesEndothelial dysfunction in the fetuses of women with gestational diabetes mellitus (GDM) is associated with their subsequent cardiovascular events. Prenatal assessment of endothelial function in fetuses exposed to intrauterine hyperglycemic environment remains challenging. The aim of this study was to assess the fetal vascular endothelial function in GDM patients using color M-mode derived aortic propagation velocity (APV) and evaluate the correlation of APV with endothelial function biomarkers.MethodsThis observational cross-sectional study included 31 gestational diabetic mothers and 30 healthy pregnant mothers from August 2019 to January 2020. Clinical data were compared between the groups. Fetal APV was measured using color M-mode echocardiography at late gestation. Concentrations of endothelial biomarkers including von Willebrand Factor (vWF), vascular endothelial-cadherin and endothelin-1 in umbilical cord serum were assessed. Measurements between diabetic group and controls were compared.ResultsvWF was the only endothelial functional marker that differed between the two groups. Fetuses in the GDM group had significantly lower APV levels and higher vWF levels compared with the healthy controls (P < 0.05). There was a moderate but significant correlation between APV and vWF (r =−0.58, P < 0.001). There were no associations between APV and ventricular wall thickness or umbilical artery pulsatility index.ConclusionsColor M-mode propagation velocity of aorta is a non-invasive, practical method that correlates well with GDM and fetal endothelial function. This novel metric could contribute to recognizing early vascular functional alterations and hence represents a potential strategy for early risk factor surveillance and risk modification.

High total cholesterol and triglycerides levels increase arginases metabolism, impairing nitric oxide signaling and worsening fetoplacental endothelial dysfunction in gestational diabetes mellitus pregnancies

Maternal physiological dyslipidemia (MPD) supports fetal development in human pregnancy. However, some women develop maternal supraphysiological dyslipidemia (MSPD: increased total cholesterol (TC) and triglycerides (TG) levels). MSPH is present in normal and also in gestational diabetes mellitus (GDM) pregnancies. MSPD and GDM associate with fetoplacental endothelial dysfunction, producing alterations in nitric oxide (NO)-L-arginine/arginase metabolism. Nevertheless, the effect of MSPD on GDM, and how this synergy alters fetoplacental endothelial function is unknown. Therefore, the aim of this study was to evaluate in human umbilical vein endothelial cells, the effects of MSPD in GDM and how these pathologies together affect the fetoplacental endothelial function. 123 women at term of pregnancy were classified as MPD (n = 40), MSPD (n = 35), GDM with normal lipids (GDM-MPD, n = 23) and with increased lipids (GDM-MSPD, n = 25). TC ≥291 mg/dL and TG ≥275 mg/dL were considered as MSPD. Endothelial NO synthase (eNOS), human cationic amino acid transporter 1 (hCat1), and arginase II protein abundance and activity, were assayed in umbilical vein endothelial cells. In MSPD and GDM-MSPD, TC and TG increased respect to MPD and GDM-MPD. eNOS activity was reduced in MSPD and GDM-MSPD, but increased in GDM-MPD compared with MPD. However, decreased tetrahydrobiopterin levels were observed in all groups compared with MPD. Increased hCat1 protein and L-arginine transport were observed in both GDM groups compared with MPD. However, the transport was higher in GDM-MSPD compared to GDM-MPD. Higher Arginase II protein and activity were observed in GDM-MSPD compared with MPD. Thus, MSPD in GDM pregnancies alters fetal endothelial function associated with NO metabolism.

Role of oxygen in fetoplacental endothelial responses: hypoxia, physiological normoxia, or hyperoxia?

During pregnancy, placental vascular growth, which is essential for supporting the rapidly growing fetus, is associated with marked elevations in blood flow. These vascular changes take place under chronic physiological low O2 (less than 2-8% O2 in human; chronic physiological normoxia, CPN) throughout pregnancy. O2 level below CPN pertinent to the placenta results in placental hypoxia. Such hypoxia can cause severe endothelial dysfunction, which is associated with adverse pregnancy outcomes (e.g., preeclampsia) and high risk of adult-onset cardiovascular diseases in children born to these pregnancy complications. However, our current knowledge about the mechanisms underlying fetoplacental endothelial function is derived primarily from cell models established under atmospheric O2 (~21% O2 at sea level, hyperoxia). Recent evidence has shown that fetoplacental endothelial cells cultured under CPN have distinct gene expression profiles and cellular responses compared with cells cultured under chronic hyperoxia. These data indicate the critical roles of CPN in programming fetal endothelial function and prompt us to re-examine the mechanisms governing fetoplacental endothelial function under CPN. Better understanding these mechanisms will facilitate us to develop preventive and therapeutic strategies for endothelial dysfunction-associated diseases (e.g., preeclampsia). This review will provide a brief summary on the impacts of CPN on endothelial function and its underlying mechanisms with a focus on fetoplacental endothelial cells.

MEG3 damages fetal endothelial function induced by gestational diabetes mellitus via AKT pathway.

To explore the role of maternally-expressed gene 3 (MEG3) in fetal endothelial dysfunction induced by gestational diabetes mellitus (GDM) and its underlying mechanism. Human umbilical vein endothelial cells (HUVECs) were extracted from GDM pregnancies and normal pregnancies. Cell proliferation, apoptosis, migration and angiogenesis of HUVECs were detected by cell counting kit-8 (CCK-8), enzyme-linked immunosorbent assay (ELISA), wound healing and tube formation assay, respectively. MEG3 expressions in HUVECs extracted from 16 GDM pregnancies and 18 normal pregnancies were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Besides, angiogenesis and MEG3 expression in HUVECs treated with glucose were detected, respectively. Proliferation, apoptosis, migration and angiogenesis were also detected after HUVECs were transfected with MEG3 lentivirus. Target genes of MEG3 were predicted by bioinformatics method and further verified by luciferase reporter gene assay. The protein expression of possible signaling pathway was detected by Western blot. HUVEC cells extracted from GDM pregnancies presented increased apoptosis and decreased proliferation, migration and angiogenesis compared with those from healthy pregnancies. Meanwhile, MEG3 was overexpressed in HUVECs extracted from GDM pregnancies compared with that of healthy pregnancies. High dose of glucose treatment led to reduced angiogenesis and elevated MEG3 expression in HUVECs. MEG3 overexpression further promoted apoptosis, but inhibited proliferation, migration and angiogenesis of HUVECs. By bioinformatics and luciferase reporter gene assay, microRNA-370-3p was found to be the target gene of MEG3 and directly targeted on AFF1. Moreover, MEG3 overexpression led to downregulated microRNA-370-3p and upregulated AFF1 mainly through inhibiting PI3K/AKT pathway. MEG3 is overexpressed in HUVECs extracted from GDM pregnancies. MEG3 damages fetal endothelial function through targeting microRNA-370-3p and AFF1 via PI3K/AKT pathway.

Preeclampsia Downregulates MicroRNAs in Fetal Endothelial Cells: Roles of miR-29a/c-3p in Endothelial Function.

Preeclampsia is a leading cause of fetal and maternal morbidity and mortality during pregnancy. Although the etiology of preeclampsia is unknown, preeclampsia offspring have increased risks of developing cardiovascular disorders in adulthood, implicating that preeclampsia programs fetal vasculature in utero. We hypothesize that preeclampsia alters expression profiles of endothelial microRNAs (miRNAs) in fetal endothelial cells and disturbs the vascular endothelial growth factor A (VEGFA)- and fibroblast growth factor 2 (FGF2)-induced endothelial function. Unpassaged (P0) human umbilical vein endothelial cells (HUVECs) were isolated immediately after cesarean-section delivery from normotensive (NT) and preeclamptic (PE) pregnancies. Differentially expressed miRNAs between P0-HUVECs from NT and PE pregnancies were identified using a miRNA polymerase chain reaction (PCR) array and confirmed using reverse transcription quantitative PCR. To determine the function of these differentially expressed miRNAs, miRNAs of interest were knocked down in NT-HUVECs following by cell functional assays. Sixteen miRNAs, including miR-29a/c-3p, were downregulated in P0-HUVECs from the PE group compared with the NT group. Bioinformatics analysis predicted the PI3K-v-akt murine thymoma viral oncogene homolog 1 (AKT) signaling pathway was dysregulated in P0-HUVECs from the PE group, which was associated with the miR-29a/c-3p downregulation. We further demonstrated that miR-29a/c-3p knockdown inhibited the VEGFA- and FGF2-induced endothelial migration as well as FGF2-induced AKT1 phosphorylation in HUVECs. However, miR-29a/c-3p knockdown did not alter the extracellular signal-regulated kinase 1/2 phosphorylation, cell proliferation, and endothelial monolayer integrity in response to VEGFA and FGF2 in HUVECs. Preeclampsia-downregulated miR-29a/c-3p may impair fetal endothelial function by disturbing the FGF2-activated PI3K-AKT signaling pathway, hence inhibiting endothelial cell migration.

N-Acetylcysteine, a glutathione precursor, reverts vascular dysfunction and endothelial epigenetic programming in intrauterine growth restricted guinea pigs.

Intrauterine growth restriction (IUGR) is associated with vascular dysfunction, oxidative stress and signs of endothelial epigenetic programming of the umbilical vessels. There is no evidence that this epigenetic programming is occurring on systemic fetal arteries. In IUGR guinea pigs we studied the functional and epigenetic programming of endothelial nitric oxide synthase (eNOS) (Nos3 gene) in umbilical and systemic fetal arteries, addressing the role of oxidative stress in this process by maternal treatment with N-acetylcysteine (NAC) during the second half of gestation. The present study suggests that IUGR endothelial cells have common molecular markers of programming in umbilical and systemic arteries. Notably, maternal treatment with NAC restores fetal growth by increasing placental efficiency and reverting the functional and epigenetic programming of eNOS in arterial endothelium in IUGR guinea pigs. In humans, intrauterine growth restriction (IUGR) is associated with vascular dysfunction, oxidative stress and signs of endothelial programming in umbilical vessels. We aimed to determine the effects of maternal antioxidant treatment with N-acetylcysteine (NAC) on fetal endothelial function and endothelial nitric oxide synthase (eNOS) programming in IUGR guinea pigs. IUGR was induced by implanting ameroid constrictors on uterine arteries of pregnant guinea pigs at mid gestation, half of the sows receiving NAC in the drinking water (from day 34 until term). Fetal biometry and placental vascular resistance were followed by ultrasound throughout gestation. At term, umbilical arteries and fetal aortae were isolated to assess endothelial function by wire-myography. Primary cultures of endothelial cells (ECs) from fetal aorta, femoral and umbilical arteries were used to determine eNOS mRNA levels by quantitative PCR and analyse DNA methylation in the Nos3 promoter by pyrosequencing. Doppler ultrasound measurements showed that NAC reduced placental vascular resistance in IUGR (P<0.05) and recovered fetal weight (P<0.05), increasing fetal-to-placental ratio at term (∼40%) (P<0.001). In IUGR, NAC treatment restored eNOS-dependent relaxation in aorta and umbilical arteries (P<0.05), normalizing eNOS mRNA levels in EC fetal and umbilical arteries (P<0.05). IUGR-derived ECs had a decreased DNA methylation (∼30%) at CpG -170 (from the transcription start site) and this epigenetic signature was absent in NAC-treated fetuses (P<0.001). These data show that IUGR-ECs have common molecular markers of eNOS programming in umbilical and systemic arteries and this effect is prevented by maternal treatment with antioxidants.

The Role of Maternal Gestational Diabetes in Inducing Fetal Endothelial Dysfunction.

Gestational diabetes mellitus (GDM) is known to be associated with fetal endothelial dysfunction, however, the mechanisms are not fully understood. This study examines the effect of maternal diabetes on fetal endothelial function and gene expression under physiological glucose conditions (5 mM). Human umbilical vein endothelial cell (HUVEC) isolated from diabetic mothers (d.HUVEC) grew more slowly than HUVEC isolated from healthy mothers (c.HUVEC) and had delayed doubling time despite increased levels of total vascular endothelial growth factor (VEGF) expression and protein production as determined by real-time PCR and ELISA respectively. Using western blot, the levels of antiproliferative VEGF165b isoform were increased in d.HUVEC relative to c.HUVEC. Successful VEGF165b knockdown by small interfering RNA (siRNA) resulted in increased proliferation of d.HUVEC measured by MTT, compared with negative siRNA control, to similar levels measured in c.HUVEC. In addition, d.HUVEC generated excess levels of ROS as revealed by 2',7' Dichlorodihydrofluorescein Diacetate (DCFH-DA) and Nitrotetrazolium blue (NBT). Using microarray, 102 genes were differentially overexpressed between d.HUVEC versus c.HUVEC (>1.5-fold change; P < 0.05). Functional clustering analysis of these differentially expressed genes revealed participation in inflammatory responses (including adhesion) which may be related to pathological outcomes. Of these genes, ICAM-1 was validated as upregulated, confirming microarray results. Additional confirmatory immunofluorescence staining revealed increased protein expression of ICAM-1 compared with c.HUVEC which was reduced by vitamin C treatment (100 μM). Thus, maternal diabetes induces persistent alterations in fetal endothelial function and gene expression following glucose normalization and antioxidant treatment could help reverse endothelium dysfunction.

IFPA Meeting 2011 workshop report II: Angiogenic signaling and regulation of fetal endothelial function; placental and fetal circulation and growth; spiral artery remodeling

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2011 there were twelve themed workshops, three of which are summarized in this report. These workshops related to vascular systems and circulation in the mother, placenta and fetus, and were divided in to 1) angiogenic signaling and regulation of fetal endothelial function; 2) placental and fetal circulation and growth; 3) spiral artery remodeling.

Endothelium-derived nitric oxide metabolites and soluble intercellular adhesion molecule-1 in diabetic and normal pregnancies

Objective: Endothelial dysfunction has been demonstrated in adult subjects with diabetes. We studied if maternal diabetes is associated with altered endothelial function in the fetus, as this might shed light on mechanisms by which adult diseases are programmed in utero. Study design: Total nitrate/nitrite (NO x ) concentration was measured spectrophotometrically with the Griess reagent method. Soluble intercellular adhesion molecule-1 (sICAM-1) concentration was measured by enzyme-linked immunoassay. Results: Venous cord serum NO x concentration at birth was highest in pregnancies complicated by type 1 diabetes (29.5 ± 1.8 μmol/l, n = 63) ( P < 0.0001 versus controls) and lowest in normal pregnancies (19.0 ± 1.0 μmol/l, n = 56). The concentration was intermediate in pregnancies complicated by gestational diabetes (23.9 ± 2.7 μmol/l, n = 24), but not significantly higher than in normal pregnancies ( P = 0.172). Venous cord serum sICAM-1 concentration did not differ between the three groups ( P = 0.191). Maternal serum NO x concentration in the third trimester was higher in pregnancies complicated by type 1 diabetes (22.9 ± 3.4 μmol/l, n = 22) than in normal pregnancies (15.4 ± 1.4 μmol/l, n = 21) ( P = 0.049). Conclusions: Increased cord serum NO x but unaltered sICAM-1 concentration in diabetic pregnancies indicates that maternal diabetes does not cause a general alteration in fetal endothelial function. The increase in cord serum and maternal serum NO x concentration in diabetic pregnancies may be due to abnormalities in insulin-induced nitric oxide release or to a diminished reactivity of the vasculature to the effects of nitric oxide.

Impairment of fetal endothelium-dependent relaxation in a rat model of preeclampsia by chronic nitric oxide synthase inhibition.

We studied fetal endothelial function in a model of preeclampsia induced by Nomega-nitro-l-arginine methylester (L-NAME) administration in pregnant rats. Aortic segments from term fetuses and 2-day-old Wistar rats treated with L-NAME (0.5 mg/mL in drinking water) (fetuses from hypertensive rats, FH, and newborns from hypertensive rats, NH) and from untreated rats (fetuses from normotensive rats, FN, and newborns from normotensive rats, NN) were obtained. Endothelium-dependent and -independent relaxations were determined by the response to 1 microM acetylcholine (ACh) and 1 microM sodium nitroprusside (SNP), respectively, after precontraction with 3 microM prostaglandin F2alpha. The role of nitric oxide in ACh relaxation was assessed by incubation with 0.1 mM N(G)-monomethyl-l-arginine (L-NMMA) or 0.1 mM l-arginine (l-Arg). Precontraction with 50 mM potassium chloride assessed the role of hyperpolarizing mechanisms. In FH, ACh-induced relaxation was reduced (FH 34.2 +/- 4%, FN 45.8 +/- 2%, P < .05), whereas that of SNP was enhanced (FH 68.4 +/- 5%, FN 50.4 +/- 4%, P < .05). l-Arg did not reverse the impairment of ACh relaxation. L-NMMA reduced ACh relaxation in FN but increased it in FH; this increase was abolished by potassium chloride precontraction and by 1 microM capsaicine, a calcitonin-gene related peptide inhibitor. The hyperpolarizing component of ACh relaxation was reduced in FH as compared with FN. By contrast, ACh relaxation was greater in NH than in NN, with the relative participation of nitric oxide and hyperpolarizing-related components being similar in both groups. Fetal ACh relaxation was impaired in this preeclampsia-like model. This impairment is probably not exclusively an effect of L-NAME but could reflect endothelial dysfunction that disappears after birth.