Dataset Information

Altered Bioavailability of Nitric Oxide and L-Arginine Is a Key Determinant of Endothelial Dysfunction in Preeclampsia.

ABSTRACT:

Background

Preeclampsia is a major cause of maternal and neonatal morbidity and mortality in sub-Saharan Africa. Evidence indicates that endothelial dysfunction is central to the pathogenesis of preeclampsia. This study assessed the level of the components of the arginine-nitric oxide pathway to evaluate endothelial dysfunction in normotensive pregnancies and pregnancies complicated with preeclampsia.

Methods

This case-control study was conducted among pregnant women who visited Comboni Hospital from January 2017 to May 2018. A total of 180 pregnant women comprising 88 preeclamptic women (PE) and 92 healthy normotensive pregnant women (NP) were recruited. Sociodemographic, clinical, and obstetric data were obtained using validated questionnaires. Blood pressure and anthropometrics were measured, and blood samples were collected for the estimation of nitric oxide (NO^∙), L-arginine, asymmetric dimethylarginine (ADMA), and 3-nitrotyrosine using an enzyme-linked immunosorbent assay technique.

Results

The mean NO^∙ (p = 0.010) and L-arginine/ADMA ratio (p < 0.0001) was significantly lower in PE compared to NP while mean L-arginine (p = 0.034), ADMA (p < 0.0001), and 3-nitrotyrosine (p < 0.0001) were significantly higher in PE than NP. ADMA showed a significant positive association with systolic blood pressure (β = 0.454, p = 0.036) in severe PE. Women with PE had significant intrauterine growth restriction (p < 0.0001) and low birth weight infants (p < 0.0001) when compared to NP.

Conclusion

Preeclampsia is associated with reduced NO^∙ bioavailability, L-arginine/ADMA ratio, and elevated levels of ADMA and 3-nitrotyrosine. Measurements of the levels of these parameters can help in the early prediction of endothelial dysfunction in preeclampsia. Exogenous therapeutic supplementation with L-arginine during pregnancy to increase the L-arginine/ADMA ratio should be considered to improve endothelial function in preeclampsia and pregnant women at risk of developing preeclampsia.

SUBMITTER: Tashie W

PROVIDER: S-EPMC7599412 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Altered Bioavailability of Nitric Oxide and L-Arginine Is a Key Determinant of Endothelial Dysfunction in Preeclampsia.

Tashie Worlanyo W Fondjo Linda Ahenkorah LA Owiredu William K B A WKBA Ephraim Richard K D RKD Asare Listowell L Adu-Gyamfi Enoch Appiah EA Seidu Laila L

BioMed research international 20201022

<h4>Background</h4>Preeclampsia is a major cause of maternal and neonatal morbidity and mortality in sub-Saharan Africa. Evidence indicates that endothelial dysfunction is central to the pathogenesis of preeclampsia. This study assessed the level of the components of the arginine-nitric oxide pathway to evaluate endothelial dysfunction in normotensive pregnancies and pregnancies complicated with preeclampsia.<h4>Methods</h4>This case-control study was conducted among pregnant women who visited C ...[more]

PMID: 33145345

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Project description:Tetrahydrobiopterin (BH4) is a key redox-active cofactor in endothelial isoform of NO synthase (eNOS) catalysis and is an important determinant of NO-dependent signaling pathways. BH4 oxidation is observed in vascular cells in the setting of the oxidative stress associated with diabetes. However, the relative roles of de novo BH4 synthesis and BH4 redox recycling in the regulation of eNOS bioactivity remain incompletely defined. We used small interference RNA (siRNA)-mediated "knockdown" GTP cyclohydrolase-1 (GTPCH1), the rate-limiting enzyme in BH4 biosynthesis, and dihydrofolate reductase (DHFR), an enzyme-recycling oxidized BH4 (7,8-dihydrobiopterin (BH2)), and studied the effects on eNOS regulation and biopterin metabolism in cultured aortic endothelial cells. Knockdown of either DHFR or GTPCH1 attenuated vascular endothelial growth factor (VEGF)-induced eNOS activity and NO production; these effects were recovered by supplementation with BH4. In contrast, supplementation with BH2 abolished VEGF-induced NO production. DHFR but not GTPCH1 knockdown increased reactive oxygen species (ROS) production. The increase in ROS production seen with siRNA-mediated DHFR knockdown was abolished either by simultaneous siRNA-mediated knockdown of eNOS or by supplementing with BH4. In contrast, addition of BH2 increased ROS production; this effect of BH2 was blocked by BH4 supplementation. DHFR but not GTPCH1 knockdown inhibited VEGF-induced dephosphorylation of eNOS at the inhibitory site serine 116; these effects were recovered by supplementation with BH4. These studies demonstrate a striking contrast in the pattern of eNOS regulation seen by the selective modulation of BH4 salvage/reduction versus de novo BH4 synthetic pathways. Our findings suggest that the depletion of BH4 is not sufficient to perturb NO signaling, but rather that concentration of intracellular BH2, as well as the relative concentrations of BH4 and BH2, together play a determining role in the redox regulation of eNOS-modulated endothelial responses.

Project description:Decreased nitric oxide (NO) bioavailability plays a critical role in the pathophysiology of preeclampsia (PE). Recent evidence indicates that S-glutathionylation may occur on the endothelial nitric oxide synthase (eNOS), leading to eNOS uncoupling, characterized by a decreased NO production and an increased generation of superoxide anion (O2•-). We hypothesized that eNOS glutathionylation may occur in PE placentas and participate in eNOS dysfunction. The glutathionylation of eNOS was investigated in thirteen PE-affected patients and in nine normal pregnancies. Immunofluorescence, confocal microscopy and western-blot experiments carried out on eNOS immunoprecipitates, revealed a high level of eNOS glutathionylation in PE placentas, mostly reversed by dithiotreitol (DTT), thus indicative of S-glutathionylation. In order to investigate whether eNOS glutathionylation may alter trophoblast migration, an important event occurring during early placentation, cultured HTR-8/SVneo human trophoblasts (HTR8) were exposed either to low pO2 (O2 1%) or to pO2 changes (O2 1-20%), in order to generate oxidative stress. Trophoblasts exposed to low pO2, did not undergo oxidative stress nor eNOS S-glutathionylation, and were able to generate NO and migrate in a wound closure model. In contrast, trophoblasts submitted to low/high pO2 changes, exhibited oxidative stress and a (DTT reversible) S-glutathionylation of eNOS, associated with reduced NO production and migration. The autonomous production of NO seemed necessary for the migratory potential of HTR8, as suggested by the inhibitory effect of eNOS silencing by small interfering RNAs, and the eNOS inhibitor L-NAME, in low pO2 conditions. Finally, the addition of the NO donor, NOC-18 (5 µM), restored in part the migration of HTR8, thereby emphasizing the role of NO in trophoblast homeostasis. In conclusion, the high level of eNOS S-glutathionylation in PE placentas provides new insights in the mechanism of eNOS dysfunction in this disease.

Dataset Information

Altered Bioavailability of Nitric Oxide and L-Arginine Is a Key Determinant of Endothelial Dysfunction in Preeclampsia.

Background

Methods

Results

Conclusion

Publications

Altered Bioavailability of Nitric Oxide and L-Arginine Is a Key Determinant of Endothelial Dysfunction in Preeclampsia.

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