Concentrations of endothelial nitric oxide synthase, angiotensin-converting enzyme, vascular endothelial growth factor and placental growth factor in maternal blood and maternal metabolic status in pregnancy complicated by hypertensive disorders

High dietary salt intake attenuates nitric oxide mediated endothelium-dependent vasodilation and increases oxidative stress in pregnancy

OBJECTIVE

This study aimed to investigate the impact of dietary salt intake during normal pregnancy on maternal microvascular and macrovascular endothelium-dependent reactivity and oxidative stress level.

MATERIALS AND METHODS

In this cross-sectional study, based on their 24-h urinary sodium excretion, pregnant women (37-40 weeks of gestation) were divided into three groups: normal salt (<5.75 g/day, N  = 12), high salt (5.75-10.25 g/day, N  = 36), and very high salt (VHS;>10.25 g/day, N  = 17). Forearm skin microvascular reactivity in response to vascular occlusion, local heating (LTH) and iontophoresis of acetylcholine (AChID), as well as brachial artery flow mediated dilation (FMD) were measured. Serum nitric oxide, endocan, 8-iso-prostaglandin F2α (8-iso-PGF2α), thiobarbituric acid reactive substances (TBARS), and ferric-reducing ability of plasma assay were measured as biomarkers of endothelial function/activation and oxidative stress.

RESULTS

Brachial artery FMD, microvascular AChID, and LTH were significantly decreased in VHS compared with NS group, while LTH was also decreased in normal salt compared with high salt group. Nitric oxide was significantly decreased in both high salt and VHS groups compared with normal salt. Endocan, 8-iso-PGF2α, and TBARS were significantly increased in VHS compared with the normal salt group.

CONCLUSION

High dietary salt intake is associated with decreased nitric oxide mediated endothelium-dependent vasodilation in peripheral microcirculation and macrocirculation of healthy pregnant women due to increased oxidative stress.

Evidence of Nitric Oxide Impairment During Hypertensive Pregnancies

Hypertensive disorders of pregnancy complicate up to 10% of pregnancies worldwide, and they can be classified into (1) gestational hypertension, (2) preeclampsia, (3) chronic hypertension and (4) chronic hypertension with preeclampsia. Nitric oxide (NO) plays an essential role in the haemodynamic adaptations observed during pregnancy. It has been shown that the nitric oxide pathway's dysfunction during pregnancy is associated with placental- and vascular-related diseases such as hypertensive disorders of pregnancy. This review aims to present a brief definition of hypertensive disorders of pregnancy and physiological maternal cardiovascular adaptations during pregnancy. We also detail how NO signalling is altered in the (a) systemic vasculature, (b) uterine artery/spiral arteries, (c) implantation and (d) placenta of hypertensive disorders during pregnancy. We conclude by summarizing the anti-hypertensive therapy of hypertensive disorders of pregnancy as a specific management strategy.

Pathophysiology of Preeclampsia and L-Arginine/L-Citrulline Supplementation as a Potential Strategy to Improve Birth Outcomes

In preeclampsia, the shallow invasion of cytotrophoblast cells to uterine spiral arteries, leading to a reduction in placental blood flow, is associated with an imbalance of proangiogenic/antiangiogenic factors to impaired nitric oxide (NO) production. Proangiogenic factors, such as vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), require NO to induce angiogenesis through antioxidant regulation mechanisms. At the same time, there are increases in antiangiogenic factors in preeclampsia, such as soluble fms-like tyrosine kinase type 1 receptor (sFIt1) and toll-like receptor 9 (TLR9), which are mechanism derivates in the reduction of NO bioavailability and oxidative stress in placenta.Different strategies have been proposed to prevent or alleviate the detrimental effects of preeclampsia. However, the only intervention to avoid the severe consequences of the disease is the interruption of pregnancy. In this scenario, different approaches have been analysed to treat preeclamptic pregnant women safely. The supplementation with amino acids is one of them, especially those associated with NO synthesis. In this review, we discuss emerging concepts in the pathogenesis of preeclampsia to highlight L-arginine and L-citrulline supplementation as potential strategies to improve birth outcomes. Clinical and experimental data concerning L-arginine and L-citrulline supplementation have shown benefits in improving NO availability in the placenta and uterine-placental circulation, prolonging pregnancy in patients with gestational hypertension and decreasing maternal blood pressure.

Soluble urinary somatic angiotensin converting enzyme is overexpressed in patients with preeclampsia: a potential new marker for the disease?

OBJECTIVE

The aim of this study was to identify and quantify urinary Angiotensin-Converting-Enzyme (ACE) in hypertensive disorders of pregnancy.

METHODS

Urine samples were analyzed by Western blot. Patients were classified into: normotensive pregnancy (N); preeclampsia and superimposed preeclampsia (PE+SPE); and gestational hypertension (GH).

RESULTS

Somatic ACE protein expression was higher in PE+SPE compared to N and GH. There was a positive correlation between ACE and urinary protein to creatinine ratio, systolic and diastolic blood pressures.

CONCLUSION

These results indicate ACE overexpression in the urine of preeclamptic patients and suggest that it may be a new marker for the disease.

A STUDY ON THE CORRELATION BETWEEN THE ENDOTHELIN-1, NITRIC OXIDE FUNCTION AND THE RENAL HEMODYNAMICS IN PATIENTS WITH HYPERTENSIVE DISORDERS IN PREGNANCY IN HUBEI

Objective: To analyze the correlation between the vascular endothelial function (characterized by endothelin-1 and nitric oxide) and the renal hemodynamics in patients with hypertensive disorders in pregnancy (HDP) by color Doppler ultrasound.

Method: Depending on the severity of the disease, 76 HDP patients were divided into three groups, namely, pregnancy-induced hypertension (PIH) group ([Formula: see text]), mild preeclampsia (PE) group ([Formula: see text]), and severe PE group ([Formula: see text]). In the meantime, 28 healthy pregnant women were selected as controls. Color Doppler ultrasound was performed to determine the following parameters in the interlobar arteries of the kidney: Resistance index (RI), peak end-diastolic velocity (EDV), pulsatility index (PI), peak systolic velocity (PSV), and S/D ratio. The correlations of these parameters with the serum levels of ET-1 and NO were then analyzed.

Result: (1) In the interlobar arteries of the kidney, RI, S/D, PI were positively significantly correlated to the serum level of ET-1 in HDP patients (All [Formula: see text]) and negatively to the serum level of NO (All [Formula: see text]). (2) RI, S/D, PI of the mild and severe PE groups were significantly higher than those of the control group (All [Formula: see text]). However, EDV of the mild and severe PE groups was significantly lower than that of the control group (All [Formula: see text]). (3) The serum level of ET-1 was significantly higher in the HDP patients than in the control group ([Formula: see text]). However, the serum level of NO was significantly lower in the former than in the latter ([Formula: see text]). As HDP became more severe, there was an elevation in the serum level of ET-1 and a decrease in NO.

Conclusion: Indicators of renal hemodynamics measured by color Doppler ultrasound were correlated to the serum levels of ET-1 and NO characterizing the vascular endothelial function. They were sensitive indicators reflecting hemodynamic changes and renal impairment in HDP patients.

New views on endothelial dysfunction in gestational hypertension and potential therapy targets

The placenta has vital roles in metabolite exchange, fetal growth, and pre-eclampsia (PE). In this review, we discuss the pathogenesis of hypertension in pregnancy, focusing on four major theories to explain PE, discussing endothelial roles in those theories. We focus in particular on the roles of nitric oxide (NO) and prostacyclin (PGI₂) in placental endothelium, and propose new hypotheses for the influence and mechanisms of endothelial NO and PGI₂ signaling pathways in PE.

Mechanisms of Endothelial Dysfunction in Pre-eclampsia and Gestational Diabetes Mellitus: Windows Into Future Cardiometabolic Health?

Placental insufficiency and adipose tissue dysregulation are postulated to play key roles in the pathophysiology of both pre-eclampsia (PE) and gestational diabetes mellitus (GDM). A dysfunctional release of deleterious signaling motifs can offset an increase in circulating oxidative stressors, pro-inflammatory factors and various cytokines. It has been previously postulated that endothelial dysfunction, instigated by signaling from endocrine organs such as the placenta and adipose tissue, may be a key mediator of the vasculopathy that is evident in both adverse obstetric complications. These signaling pathways also have significant effects on long term maternal cardiometabolic health outcomes, specifically cardiovascular disease, hypertension, and type II diabetes. Recent studies have noted that both PE and GDM are strongly associated with lower maternal flow-mediated dilation, however the exact pathways which link endothelial dysfunction to clinical outcomes in these complications remains in question. The current diagnostic regimen for both PE and GDM lacks specificity and consistency in relation to clinical guidelines. Furthermore, current therapeutic options rely largely on clinical symptom control such as antihypertensives and insulin therapy, rather than that of early intervention or prophylaxis. A better understanding of the pathogenic origin of these obstetric complications will allow for more targeted therapeutic interventions. In this review we will explore the complex signaling relationship between the placenta and adipose tissue in PE and GDM and investigate how these intricate pathways affect maternal endothelial function and, hence, play a role in acute pathophysiology and the development of future chronic maternal health outcomes.

Molecular determinants of microvascular dysfunction in hypertensive pregnancy and preeclampsia

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.

Towards a multi protein and mRNA expression of biological predictive and distinguish model for post stroke depression

Previous studies suggest that neurotrophic factors participate in the development of stroke and depression. So we investigated the utility of these biomarkers as predictive and distinguish model for post stroke depression (PSD). 159 individuals including PSD, stroke without depression (Non-PSD), major depressive disorder (MDD) and normal control groups were recruited and examined the protein and mRNA expression levels of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptors (VEGFR2), placental growth factor (PIGF), insulin-like growth factor (IGF-1) and insulin-like growth factor receptors (IGF-1R). The chi-square test was used to evaluate categorical variable, while nonparametric test and one-way analysis of variance were applied to continuous variables of general characteristics, clinical and biological changes. In order to explore the predictive and distinguish role of these factors in PSD, discriminant analysis and receiver operating characteristic curve were calculated. The four groups had statistical differences in these neurotrophic factors (all P < 0.05) except VEGF concentration and IGF-1R mRNA (P = 0.776, P = 0.102 respectively). We identified these mRNA expression and protein analytes with general predictive performance for PSD and Non-PSD groups [area under the curve (AUC): 0.805, 95% CI, 0.704-0.907, P < 0.001]. Importantly, there is an excellent predictive performance (AUC: 0.984, 95% CI, 0.964-1.000, P < 0.001) to differentiate PSD patients from MDD patients. This was the first study to explore the changes of neurotrophic factors family in PSD patients, the results intriguingly demonstrated that the combination of protein and mRNA expression of biological factors could use as a predictive and discriminant model for PSD.

Upregulation of P53 promoted G1 arrest and apoptosis in human umbilical cord vein endothelial cells from preeclampsia

OBJECTIVE

Preeclampsia is a leading cause of maternal and perinatal morbidity and mortality. Current research has focused on endothelial dysfunction regarding pathogenesis of preeclampsia. However, very limited or no studies so far have been performed to assess possible damaged endothelial cell growth/development in the placenta-umbilical cord circulation system in human preeclampsia.

METHODS

We isolated and cultured human umbilical cord vein endothelial cells (HUVECs) from normal and preeclampsia pregnancies in vitro. We used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay to measure cell growth and flow cytometric analysis to determine cell-cycle distribution. Annexin V-fluorescein isothiocyanate/propidium iodide double staining was employed for cell apoptosis experiments.

RESULTS

The study showed that the cell growth was significantly suppressed, accompanied by the increased G1 arrest and apoptosis in cultured HUVECs from preeclampsia pregnancies comparing with normotensive controls. Protein P53 was upregulated in the cultured HUVECs from preeclampsia pregnancies, which induced G1 arrest, followed by upregulating P21 expression, and downregulating cyclin E expression and CDK2-cyclin E complexes. On the other hand, upregulation of P53 also activated Bax gene and repressed Bcl-2 and BIRC5 genes, resulting in an increase of the Bax/Bcl-2 ratio and subsequently activating caspase cascade, ultimately led to an initiation of the apoptotic machinery.

CONCLUSION

These results indicated that in preeclampsia, vascular endothelial cells could be damaged and cellular proliferation was depressed in human placenta-umbilical cord circulation, adding new information on endothelial cell injury for better understanding the pathogenesis of preeclampsia.

Involvement of dysregulated IKCa and SKCa channels in preeclampsia

INTRODUCTION

Excessive constriction of placental chorionic plate arteries (CPAs) may be associated with preeclampsia (PE). Nitric oxide (NO) as well as intermediate and small Ca²⁺-activated K⁺ channels (IK_Ca and SK_Ca) plays vital roles in vasodilation of CPAs. We hypothesized that dysregulated IK_Ca and SK_Ca channels may be involved in the pathogenesis of PE mediated by the impaired NO system on CPAs.

METHODS

The location of IK_Ca and SK_Ca channels, activities of NO synthases (NOS), and expression levels of these molecules were studied on CPAs from 30 normal pregnancies and 30 PE. The vasodilating function of CPAs was measured under openers or blockers of IK_Ca/SK_Ca channels in the presence or absence of NO donor or inhibitor.

RESULTS

IK_Ca and SK_Ca channels were located both on endothelium and on smooth muscles of CPAs and the expressions of them were downregulated in PE women comparing to those in normal pregnant women. The protein expressions of endothelial NOS (eNOS) and inducible NOS (iNOS) were downregulated on CPAs in PE accompanied by decreased activity of eNOS. Notably, the vasodilatory functions mediated by IK_Ca/SK_Ca channels and by NO were aberrant on preeclamptic CPAs. In addition, IK_Ca and SK_Ca channels were responsible for nitric oxide (NO)-attributable vasorelaxation and activity modulation of NO synthases.

CONCLUSIONS

This study provides evidence that dysregulated IK_Ca and SK_Ca channels might contribute to fetal pathogenesis of PE through direct promotion of vascular constriction of CPAs and through affecting functions of NO and activities of NOS.

Matrix Metalloproteinases in Normal Pregnancy and Preeclampsia

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.

The NOX2-derived reactive oxygen species damaged endothelial nitric oxide system via suppressed BKCa/SKCa in preeclampsia

The endothelial nitric oxide (NO) system may be damaged in preeclampsia; however, the involved mechanisms are unclear. In this study, we used primary human umbilical vein endothelial cells (HUVECs) to evaluate the endothelial NO system in preeclampsia and to determine the underlying mechanisms that are involved. We isolated and cultured HUVECs from normal and preeclamptic pregnancies and evaluated endothelial NO synthase enzyme (eNOS) expression and NO production. Whole-cell K⁺ currents and oxidative stress were also determined in normal and preeclamptic HUVECs. Compared with normal HUVECs, eNOS expression, NO production and whole-cell K⁺ currents in preeclamptic HUVECs were markedly decreased, whereas oxidative stress was significantly increased. The decreased K⁺ currents were associated with damaged Ca²⁺-activated K⁺ (KCa) channels, especially the large (BKCa) and small (SKCa) conductance KCa channels, and were involved in the downregulated eNOS expression in preeclamptic HUVECs. Moreover, the increased oxidative stress detected in preeclamptic HUVECs was mediated by NADPH (nicotinamide adenine dinucleotide phosphate) oxidase 2 (NOX2)-dependent reactive oxygen species overproduction that could downregulate whole-cell K⁺ currents, eNOS expression and NO production. Taken together, our study indicated that the increased oxidative stress in preeclamptic HUVECs could downregulate the NO system by suppressing BKCa and SKCa channels. Because the damaged NO system was closely related to endothelial dysfunction, this study provides important information to further understand the pathological process of endothelial cell dysfunction in preeclampsia.

Mechanisms of Endothelial Dysfunction in Hypertensive Pregnancy and Preeclampsia

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.

κ-Opioid Receptor Stimulation Improves Endothelial Function via Akt-stimulated NO Production in Hyperlipidemic Rats

This study was designed to investigate the effect of U50,488H (a selective κ-opioid receptor agonist) on endothelial function impaired by hyperlipidemia and to determine the role of Akt-stimulated NO production in it. Hyperlipidemic model was established by feeding rats with a high-fat diet for 14 weeks. U50,488H and nor-BNI (a selective κ-opioid receptor antagonist) were administered intraperitoneally. In vitro, the involvement of the PI3K/Akt/eNOS pathway in the effect of U50,488H was studied using cultured endothelial cells subjected to artificial hyperlipidemia. Serum total cholesterol and low-density lipoprotein cholesterol concentrations dramatically increased after high-fat diet feeding. Administration of U50,488H significantly alleviated endothelial ultrastructural destruction and endothelium-dependent vasorelaxation impairment caused by hyperlipidemia. U50,488H also increased Akt/eNOS phosphorylation and serum/medium NO level both in vivo and in vitro. U50,488H increased eNOS activity and suppressed iNOS activity in vivo. The effects of U50,488H were abolished in vitro by siRNAs targeting κ-opioid receptor and Akt or PI3K/Akt/eNOS inhibitors. All effects of U50,488H were blocked by nor-BNI. These results demonstrate that κ-opioid receptor stimulation normalizes endothelial ultrastructure and function under hyperlipidemic condition. Its mechanism is related to the preservation of eNOS phosphorylation through activation of the PI3K/Akt signaling pathway and downregulation of iNOS expression/activity.