Association of common eNOS/NOS3 polymorphisms with preeclampsia in Tunisian Arabs

Association of endothelial nitric oxide synthase gene variants in pre-eclampsia: an updated systematic review and meta-analysis

INTRODUCTION

Three common endothelial nitric oxide synthase (eNOS) gene variants are existed such as; G-894T, T-786C, and variable number tandem repeats in intron-4 (VNTR intron-4) which has been proposed to be linked with PE. However, there is still debate regarding the findings. To address this, a review was conducted to assess the potential association of eNOS gene variants at these positions with the risk of PE.

METHODS

PubMed, Scopus, Science Direct, Hinari, and African Journal Online databases and Google Scholar search engines were utilized to search studies published in English-language until 30 January 2023. The Joanna Briggs Institute Meta-Analysis instrument was used for data extraction process and the Newcastle-Ottawa Scale was used to appraise the quality of the included studies. Meta-regression analysis was conducted using Stata 14 statistical software. The pooled odds ratios (ORs) of fixed and random effect models were utilized to evaluate the association of eNOS gene polymorphism with the risk of PE at 95% CI. Publication bias was assessed using Egger's test and a funnel plot.

RESULTS

The study included 47 observational studies involving 13,795 pregnant women (6216 cases and 7579 controls). Pregnant women carrying TT and CC genotypes of eNOS gene at 894 and 786 positions were found to have a greater probability of developing PE as compared to GG and TT genotypes (OR = 1.54 vs. 1.43 and CI: 1.12 - 2.14 vs.1.02 - 2.00 at 95% CI), respectively. However, a significant association was not observed between aa genotype of eNOS gene in VNTR intron-4 region and risk of PE as compared to bb genotype (OR =1.26, 95% CI: 0.83 - 1.89). The allelic model of eNOS gene at all positions showed nonsignificant association with the risk of PE.

CONCLUSIONS

The women having eNOS gene variants at 894 and 786 positions showed a significant association with the risk of PE. Yet, the women having eNOS gene variant at intron-4 region showed nonsignificant association with the risk of PE. Thus, this study suggests that eNOS gene variants may play a role in the development of PE, but large-scale studies are required to inaugurate concrete evidence on the roles of eNOS gene variants in PE pathogenesis.

The eNOS-G894T genetic polymorphism and risk of preeclampsia: A case-control study, an updated meta-analysis, and a bioinformatic assay

OBJECTIVES

Preeclampsia (PE) is a leading cause of maternal death worldwide and involves vascular endothelial dysfunction. The aim of this study was to investigate the association of the G894T polymorphism in the endothelial nitric oxide synthase (eNOS) gene and the risk of preeclampsia in a case-control design in an Iranian population, which was followed by a meta-analysis and an in silico approach.

METHODS

In the case-control study, 300 people including 135 pregnant women with preeclampsia and 165 healthy pregnant women were included. The genotype of G894T polymorphism was determined by the PCR-RFLP method. We searched authoritative scientific databases to find eligible studies for meta-analysis. The odds ratio with a 95% confidence interval was estimated to find the strength of the association of the mentioned polymorphism with the risk of preeclampsia. In addition, the effect of G894T transversion on eNOS gene function was evaluated by some bioinformatics tools.

RESULTS

Our case-control data showed that the G894T polymorphism is associated with an increased risk of preeclampsia. In the meta-analysis, 33 eligible studies were included, and the results showed that the G894T polymorphism is associated with an increased risk of preeclampsia in the overall analysis and some stratified analyses. In addition, the structural analysis showed that the G894T variant can affect the splicing process as well as the protein stability.

CONCLUSIONS

Based on the results, the aforementioned polymorphism may be a risk factor for preeclampsia and could be considered a potential molecular biomarker for screening susceptible individuals.

Association of Endothelial Nitric Oxide Synthase 894G > T Polymorphism with Preeclampsia Risk: A Systematic Review and Meta-Analysis based on 35 Studies

Several case-control studies have been performed to investigate the association between 894 G > T polymorphism in endothelial nitric oxide synthase (eNOS) gene and susceptibility to preeclampsia. However, the results were inconsistent and inconclusive. Therefore, we conducted this meta-analysis to investigate the association. Methods: All studies published up to September 30, 2019 were identified by searching electronic databases such as PubMed, EMBASE, CNKI, and WANFANG. Results: A total of 35 case- control studies with 4,254 cases and 5,801 controls were selected. There was a significant association between the eNOS 894 G > T and preeclampsia risk. When stratified by ethnicity, an increased risk of preeclampsia was found in Caucasian and Mixed populations, but not in Asians or Africans. Conclusion: Based on our meta-analysis, the eNOS 894 G > T polymorphism was associated with an increased risk of preeclampsia, especially among Caucasian and Mixed populations.

Association of endothelial nitric oxide synthase gene variants with preeclampsia

Background

Preeclampsia (PE) is a complex pregnancy hypertensive disorder with multifaceted etiology. The endothelial nitric oxide synthase (eNOS) gene and nitric oxide (NO) levels has been reported to be associated with PE predisposition in various populations. Therefore, present study was designed to investigate the role of NO levels and eNOS gene variants in preeclamptic women in Pakistan.

Methods

A total of 600 women were evaluated, 188 of PE with mild features, 112 of PE with severe features and 300 normotensive pregnant women. NO levels were detected by Greiss reaction method and genotyping following sequencing was conducted for eNOS gene variants. Further insilico studies were performed to get insights into the structural and functional impact of identifies mutation on eNOS protein as well as on protein regulation.

Results

Reduced concentrations of NO were reported in all PE groups (p < 0.05) as compared to controls. The frequency of c.894 T (p.298Asp) and g.-786C alleles were significantly associated with PE. In addition, novel homozygous variant g.2051G > A was also significantly associated with PE when compared to normotensive women. Dynamic simulation studies revealed that Glu298Asp mutation destabilize the protein molecule and decrease the overall stability of eNOS protein. Molecular docking analysis of mutant promoter with transcription factors STAT3 and STAT6 proposed changes in protein regulation upon these reported mutations in upstream region of the gene.

Conclusion

Considering the results of current study, the functional alterations induced by these variants may influence the bioavailability of NO and represents a genetic risk factor for increased susceptibility to PE. However, large studies or meta-analysis are necessary to validate these findings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12978-021-01213-9.

Preeclampsia (PE) is a complex pregnancy hypertensive disorder with multifaceted etiology characterized by increased hypertension and proteinuria after 20 weeks of gestation. The present study was directed to determine the role of eNOS in susceptibility to PE and the association of c.894G > T (p.(Glu298Asp), intron 4b/4a, g.-786 T > C and other possible variants of eNOS gene with preeclampsia in Pakistani population. Computational analysis of identified variants in the coding and non-coding region of the eNOS gene was also conducted to determine the change in gene regulation and further protein stability. A total of 600 women were evaluated, 188 with mild and 112 with PE with severe features PE with 300 normotensive pregnant women. NO levels and genotyping following sequencing was conducted for eNOS gene variants. Further insilico studies were performed to get insights into the structural and functional impact of identifies mutation on eNOS protein as well as on protein regulation. Data from the current study suggest that there might be other risk variants of the eNOS gene (g.2051G > A and g.1861G > A) and lower levels of serum NO that confers in an increased risk of PE. The detailed computational investigation further confirmed the deformities and changes in protein flexibility upon Glu298Asp. These structural alterations might be associated with preeclampsia. Variants in the promoter region of the eNOS gene further validate the change in gene regulation for the onset of disease. Identification of key structural and functional features in eNOS protein and gene regulatory region might be used for designing specific drugs for therapeutic purpose.

Association Between Endothelial Nitric Oxide Synthase (eNOS) -786 T/C and 27-bp VNTR 4b/a Polymorphisms and Preeclampsia Development

The aim of the present study was to analyze the distribution of genotypes and haplotypes of functional eNOS gene polymorphisms in the promoter (-786 T/C), intron 4 (VNTR4b/a) and exon 7 (894 G/T), in Serbian population of pregnant women, and establish a possible association between these polymorphisms and preeclampsia development. DNA was isolated from venous blood samples of 50 heathy pregnant women and 50 preeclampsia patients. Polymerase Chain Reaction/Restriction Fragment Length Polymorphism (PCR/RFLP) technique, with appropriate sets of primers and specific restriction enzymes, was used to determine polymorphisms in eNOS gene. Statistical analysis was done using the SPSS and HAPLOVIEW software packages. eNOS -786 T/C polymorphism was significantly associated with preeclampsia (P = 0.006). Homozygotes for the VNTR polymorphism had also an elevated risk of developing preeclampsia (OR=7.68, 95%CI (0.89-65.98)), especially the mild (OR=9.33, 95%CI (0.98-88.57)) and late form (OR=8.52, 95%CI (0.90-80.58)). The 894 G/T polymorphism was not associated with preeclampsia. "G-C-b" and "T-4a-T" haplotypes were more frequent in preeclampsia, though without reaching statistical significance. -786 T/C and VNTR 4b/a eNOS gene polymorphisms were associated with preeclampsia risk in Serbian patients.

Preeclampsia: inflammatory signature of decidual cells in early manifestation of disease

INTRODUCTION

Preeclampsia is a pregnancy-specific complication characterized by hypertension in combination with proteinuria and/or various manifestations of multiple organ failure. It is believed that etiology of preeclampsia lies in dysfunction of the placenta and disorder of the maternal-fetal interactions. In preeclampsia decidual membrane, the maternal part of the placenta which normally supports immunological tolerance of the maternal organism to the semi-allogeneic fetus, becomes a site of inflammation.

METHODS

The aim of our study was to characterize the phenotype of decidual macrophages and plasma profiles in patients with late- and early-onset preeclampsia as compared with controls (n = 43). Decidual cells were obtained by enzymatic digestion method and characterized by flow cytometry analysis, real-time PCR, bioinformatics analysis, immunohistochemistry, and Western blot. Plasma samples were analyzed by multiplex assay.

RESULTS

The number of inflammation-associated CD86+ and CX3CR1+ cells was significantly higher in the early-onset preeclampsia while the portion of CD163+ cells was significantly higher among studied groups. We observed significant increase of endothelin-1 gene expression and a significant decrease in eNOS and GNB3 expression and TGFβ relative protein level in decidual cells of the early-onset preeclampsia samples. We also revealed elevation of pro- and anti-inflammatory cytokines in plasma of preeclampsia groups.

DISCUSSION

Our findings reflect profound early-onset preeclampsia-associated alterations in the decidua and emphasize the importance of the decidua as a link in the development of preeclampsia.

Placental endothelial nitric oxide synthase expression and role of oxidative stress in susceptibility to preeclampsia in Pakistani women

BACKGROUND

Preeclampsia (PE): a hypertensive disorder of pregnancy characterized by de novo development of concurrent hypertension and proteinuria. The prevailing theory determined that PE starts from the placenta and ends in the maternal endothelium. Role of endothelial dysfunction in the onset of PE has been reported in different populations. Therefore, present study was designed to investigate the localization and expression of endothelial nitric oxide synthase (eNOS) and role of oxidative stress markers in preeclamptic Pakistani women.

METHODS

A total of 400 blood samples (PE = 200, controls = 200) and 100 placental tissues (PE = 50, controls = 50) were recruited from pregnant women. Reactive oxygen species (ROS), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (POD) levels were analyzed through spectrophotometer. Immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR) were carried out to estimate the localization and expression of eNOS in the placentas of PE patients and healthy pregnant women.

RESULTS

Significantly increased levels of POD (0.01), TBARS (0.04), and ROS (p ≤ .001) were determined in preeclamptic women while, nonsignificant change in SOD and CAT was observed in both groups. Reduced eNOS immunoreactivity (p ≤ .001) and mRNA abundance (p ≤ .001) was observed in preeclamptic group as compared to control group.

CONCLUSION

Considering the results of current study, it is concluded that decreased eNOS expression and oxidative stress could play a role in the pathology of PE seen both in placenta and ultimately in maternal endothelium. However, large studies are necessary to validate these findings to prevent maternal and neonatal morbidity and mortality in Pakistani population.

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.

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.

Maternal/fetal eNOS-Glu298Asp genotypes and their influence on the severity, prognosis, and lipid profile of preeclampsia

OBJECTIVES

To analyze the contribution of maternal eNOS-Glu298Asp genotypes and also the association with fetal genotypes to the development of preeclampsia, prognosis, and maternal dyslipidemia.

METHODS

Sixty-nine pairs of preeclamptic mothers/newborns and 94 pairs of normotensive mothers/newborns were genotyped for eNOS-Glu298Asp using PCR-RFLP methods.

RESULTS

Women carriers of at least one Asp298 allele had a 1.53-fold (p = NS), 1.88-fold (p = NS), and 2.08-fold (p = .05), respectively, increased risk to develop PIH, mild, or severe preeclampsia. If both the mother and the newborn were carriers of the Asp298 allele, the risk for preeclampsia was 5.09-fold higher (p < .001). Preeclamptic women with severe preeclampsia had significantly higher cholesterol (mg/dl, 287.23 ± 43.01 versus 235.36 ± 45.01, p = .02) and LDL (mg/dl, 194.9 ± 42.8 versus 144.98 ± 54.84, p = .04) levels and lower HDL levels (mg/dl, 32.12 ± 5.48 versus 57.84 ± 20.59, p = .02) compared to noncarriers. Also, higher LDL levels (mg/dl, 188.76 ± 46.61 versus 136.75 ± 41.85, p = .03) and lower HDL levels (mg/dl, 32.8 ± 5.64 versus 61.06 ± 22.45, p = .02) were found in preeclamptic women with severe preeclampsia whose newborns were carriers of the Asp298 allele.

CONCLUSIONS

The eNOS-Glu298Asp variant (in mothers and newborns) in association with dyslipidemia could affect bioavailability of NO and could represent an increased risk for 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.

Associations between nitric oxide synthase 3 gene polymorphisms and preeclampsia risk: a meta-analysis

Previous studies have examined the role of three NOS3 gene polymorphisms [G894T, T-786C, and the variable number of tandem repeats 4b/a (VNTR 4b/a)] in the susceptibility to preeclampsia with inconclusive findings. We therefore conducted an updated meta-analysis by including more studies. The most appropriate genetic model was chosen for each polymorphism by using a well-established method. Pooled results indicated that, compared with the GT + GG genotype, the TT genotype of G894T was associated with an increased risk of preeclampsia (odds ratio (OR) = 1.46; 95% confidence interval (CI) = 1.21–1.77, P < 0.001; I² = 40.2%). The CC genotype of T-786C was also associated with a higher risk of preeclampsia (OR = 1.30; 95% CI = 1.07–1.58, P = 0.034; I² = 46.9%) than the CT + TT genotype. No association was found for VNTR 4b/a. Stratified analysis indicated that the increased risk was evident for high-quality studies both for G894T and T-786C, and for studies conducted among Caucasians and Africans for T-786C. However, the increased risk for T-786C among Africans needs further confirmation due to the high probability of false-positive reports. Our results suggested that G894T and T-786C polymorphisms, but not VNTR 4b/a, were associated with an increased risk of preeclampsia.