Searching for preeclampsia genes: the current position

Evaluation and Management of Hypertensive Disorders of Pregnancy

Hypertensive disorders of pregnancy complicate up to 10% of pregnancies and remain the major cause of maternal and neonatal morbidity and mortality. Hypertensive disorders of pregnancy can be classified into four groups depending on the onset of hypertension and the presence of target organ involvement: chronic hypertension, preeclampsia, gestational hypertension, and superimposed preeclampsia on chronic hypertension. Hypertension during pregnancy is associated with a higher risk of cardiovascular disease and kidney failure. Early diagnosis and proper treatment for pregnant women with hypertension remain a priority since this leads to improved maternal and fetal outcomes. Labetalol, nifedipine, methyldopa, and hydralazine are the preferred medications to treat hypertension during pregnancy. In this comprehensive review, we discuss the diagnostic criteria, evaluation, and management of pregnant women with hypertension.

The Role of Endothelial Dysfunction in the Pathogenesis of Pregnancy-Related Pathological Conditions: A Review

In the recent decades, endothelial dysfunction (ED) has been recognized as a significant contributing factor in the pathogenesis of many pathological conditions. In interaction with atherosclerosis, hypercholesterolemia, and hypertension, ED plays a crucial role in the pathogenesis of coronary artery disease, chronic renal disease, and microvascular complications in diabetes mellitus. Although ED plays a significant role in the pathogenesis of several pregnancy-related disorders such as preeclampsia, HELLP syndrome, fetal growth restriction, and gestational diabetes mellitus, the exact pathogenetic mechanisms are still a matter of debate. The increased prevalence of these entities in patients with preexisting vascular diseases highlights the essential pathological role of the preexisting ED in these patients. The abnormal uteroplacental circulation and the release of soluble factors from the ischemic placenta into the maternal bloodstream are the main causes of the maternal ED underlying the characteristic preeclamptic phenotype. Besides the increased risk for maternal and fetal poor outcomes, the preexisting ED also increases the risk of development of future cardiovascular diseases in these patients. This study aimed to look deeper into the role of ED in the pathogenesis of several pregnancy-related hypertensive and liver diseases. Hopefully, it could contribute to improvement of the awareness, knowledge, and management of these conditions and also to the reduction of the adverse outcomes and additional long-term cardiovascular complications.

Histopathologic and Transcriptomic Profiling Identifies Novel Trophoblast Defects in Patients With Preeclampsia and Maternal Vascular Malperfusion

Preeclampsia (PE) is a heterogeneous disease for which the current clinical classification system is based on the presence or absence of specific clinical features. PE-associated placentas also show heterogeneous findings on pathologic examination, suggesting that further subclassification is possible. We combined clinical, pathologic, immunohistochemical, and transcriptomic profiling of placentas to develop integrated signatures for multiple subclasses of PE. In total, 303 PE and 1388 nonhypertensive control placentas were included. We found that maternal vascular malperfusion (MVM) in the placenta was associated with preterm PE with severe features and with small-for-gestational-age neonates. Interestingly, PE placentas with either MVM or no histologic pattern of injury showed a linear decrease in proliferative (p63+) cytotrophoblast per villous area with increasing gestational age, similar to placentas obtained from the nonhypertensive patient cohort; however, PE placentas with fetal vascular malperfusion or villitis of unknown etiology lost this phenotype. This is mainly because of cases of fetal vascular malperfusion in placentas of patients with preterm PE and villitis of unknown etiology in placentas of patients with term PE, which are associated with a decrease or increase, respectively, in the cytotrophoblast per villous area. Finally, a transcriptomic analysis identified pathways associated with hypoxia, inflammation, and reduced cell proliferation in PE-MVM placentas and further subclassified this group into extravillous trophoblast-high and extravillous trophoblast-low PE, confirmed using an immunohistochemical analysis of trophoblast lineage-specific markers. Our findings suggest that within specific histopathologic patterns of placental injury, PE can be subclassified based on specific cellular and molecular defects, allowing the identification of pathways that may be targeted for diagnostic and therapeutic purposes.

Preeclampsia, Natural History, Genes, and miRNAs Associated with the Syndrome

Preeclampsia (PE) is a hypertensive disease that affects pregnant women after 20 weeks of gestation. This disease is associated with an important risk of maternal and fetal mortality. PE is described as a placental pathology because, after delivery, most women recover normal arterial pressure. Poor invasion of the spiral arteries is a phenomenon well described in PE; this leads to a hypoxic uterine bed and imbalance of antiangiogenic and proangiogenic factors in the uteroplacental region, which in turn triggers the disease phenotype. The causes of the pathology are unclear; nevertheless, numerous approaches, including next-generation sequencing, association, and case control and miRNA studies, have shed light on the genetic/molecular basis of PE. These studies help us better understand the disease to advance new treatment strategies.

The association of MOV10 polymorphism and expression levels with preeclampsia in the Chinese Han population

BACKGROUND

To assess the relationship between MOV10 rs2932538 polymorphism and susceptibility to preeclampsia (PE) in the Chinese Han population and to investigate whether the placental expression of MOV10 have association with PE.

METHODS

We enrolled 1021 pregnant women with PE and 1594 normotensive pregnant women to analyze genotyping of MOV10 rs2932538. Clinical data and related test results of all subjects were collected and analyzed. For volunteers providing placentas, real-time PCR, Western blot, and immunohistochemistry were applied to assess the expression level of MOV10.

RESULTS

There was significant statistical difference between preeclamptic patients and healthy subjects in genotype distributions and alleles. The frequencies of genotypes TT+CT were significantly associated with the increased risk of preeclampsia. Besides, T alleles were found to be related to a higher risk of PE. Significant statistical difference was also observed on distributions of genotype in PE without/with severe features group compared or early onset/late onset versus controls. The placental expression of MOV10 was lower in preeclamptic women, however, no relationship was found between MOV10 expression level and MOV10 rs2932538 genotypes.

CONCLUSION

This study suggests that MOV10 rs2932538 polymorphism may be associated with PE susceptibility in the Chinese Han population. The placental expression of MOV10 decrease in PE but have no relationship with rs2932538 polymorphism.

STOX1 gene Y153H polymorphism is associated with early-onset preeclampsia in Turkish population

Preeclampsia (PE) is a disease of pregnancy that causes of maternal and prenatal morbidity worldwide. Studies indicate that variations in STOX1 gene may be a direct risk factor to PE but controversial results regarding the relationship of Y153H variation in the second exon of STOX1 gene with PE have been ongoing since 2005. The aim of this study was to identify if there is any correlation between Y153H polymorphisms and PE in Turkish preeclampsia patients. We performed polymerase chain reaction- restriction fragment lengthpolymorphism(PCR-RFLP) analysis in 500 pregnant women, of whom 373 pregnant women with early onset PE (EOPE) and 500 normal pregnant women. The relationship between STOX1 Y153H polymorphism and EOPE/LOPE was evaluated by statistical analysis. We found that STOX1 Y153H polymorphism is a risk factor for EOPE (p = 0.03). The odds ratio was 1,45 (CI 95% = 1,03-2,05). No relationship between STOX1 Y153H polymorphisms and LOPE (p = 0.13) was found. STOX1 gene Y153H polymorphism is associated with the risk ofearly onset of pre-eclampsiain a Turkish population. The results provide further evidence of the role of STOX1 in the pathophysiology of this disease.

Vascular endothelial growth factor C/A 2578 gene polymorphism and umbilical artery Doppler in preeclamptic women

INTRODUCTION

Preeclampsia is strongly associated with placental hypoperfusion. Genetic factors have an impact on the pathogenesis of preeclampsia. The aim is to assess the association of Vascular Endothelial Growth Factor (C2578A) gene polymorphism with the occurrence and severity of preeclampsia and the umbilical artery Doppler changes among preeclamptic women.

MATERIALS AND METHODS

This case-control study was conducted in clinical and Chemical pathology and Obstetrics departments in Beni- Suef University, Egypt. Two hundred and ninety pregnant women above 20 weeks gestational age until delivery were divided into 2 main groups. The patient group included 145 preeclamptic women who were further sub grouped according to the severity of preeclampsia into 82 severe and 63 mild cases. Control group included 145 normotensive pregnant women. Our primary outcome was detection of VEGF C 2578 A gene mutations by a polymerase chain reaction. A secondary outcome was Doppler changes in the pulsatility index of the umbilical artery compared with VEGF genotypes.

RESULTS

Our study showed that VEGF C 2578 A genotype and alleles frequencies were not related to the occurrence of preeclampsia (p-value 0.513 and 0.549, respectively), odds ratio (95%CI) 1.154 (0.724-1.848). Mild preeclamptic cases showed no significance comparing VEGF genotypes studied and pulsatility index of the umbilical artery. However, severe cases showed p-value < 0.0001.

CONCLUSION

We concluded that VEGF 2578C/A polymorphism had no association with the occurrence of preeclampsia in studied groups, whereas there was a significant relationship among severe cases between CA and CC genotypes and pulsatility index of the umbilical artery.

The role of two common FOXP3 gene promoter polymorphisms in preeclampsia in a Turkish population: a case-control study

Preeclampsia (PE), which occurs in approximately 5% of pregnancies worldwide and constitutes clinically serious complications in 2-3%, is one of the leading causes of maternal and prenatal morbidity and mortality. Recent studies report that regulatory T (Treg) cells, which act as immunosuppressant, are associated with PE. It is clearly defined that FOXP3/Scurfin (Forkhead Box P3) is involved in the development and function of Tregs. However, there are different conclusions regarding the relationship between PE and FOXP3 gene polymorphisms for different populations. For this reason, in this study we investigate the association between FOXP3 gene promoter region polymorphisms and PE in a Turkish population 500 PE patients and 500 healthy pregnant women. Blood samples taken from pregnant women were studied by PCR-RFLP method. As a result, rs2232365 polymorphism was significantly associated with disease (p < .0001) while no significant association was found between rs3761548 polymorphism and the disease (p = .17). Based on these results, it is though that FOXP3 rs2232365 polymorphism may be predisposed to PE development in terms of Turkish population. However, further and functional studies are needed in terms of other polymorphisms and mutations.IMPACT STATEMENTWhat is already known on this subject? A number of recent publications suggest that Tregs may play a role in the pathogenesis of PE. It is known that a stable and high FOXP3 expression is required to maintain the suppressive T cell function of Tregs. Down regulation of FOXP3 in PE has been reported in many previous studies, but the mechanism is still uncertain.What do the results of this study add? Our study has examined two FOXP3 promoter region polymorphisms in terms of Turkish population for the first time. Rs2232365 polymorphism associated with the disease in heterozygous genotype.What are the implications of these findings for clinical practice and/or further research? It has been shown that FOXP3 gene promoter region polymorphisms may be associated with PE for Turkish population. Our results can be a guide for more detailed statistical evaluations and functional studies.

The possible role of maternal and placental vitamin D receptor polymorphisms and haplotypes in pathogenesis of preeclampsia

Purpose: Vitamin D deficiency may be a main causative agent in the pathogenesis of preeclampsia (PE). The actions of the active form of vitamin D are mediated via the vitamin D receptor (VDR), which is expressed in numerous organs including placenta. Therefore, we evaluated the potential relationship between maternal and placental VDR polymorphisms and the predisposition to PE in an Iranian population.Methods: This case-control study surveyed 152 PE and 160 normotensive pregnant women. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was performed to examine the maternal and placental VDR Fok1 rs2228570, Bsm1 rs1544410, Taq1 rs731236, and Apa1 rs7975232 polymorphisms.Results: The maternal but not placental VDR FokI Ff genotype, was significantly lower in PE women (P = .02 and P = .06, respectively). The maternal and placental VDR FokI polymorphism was associated with lower PE risk in the dominant model (Ff+ff vs. FF) and these genotypes could decrease PE risk (OR, 0.5 [95% CI, 0.3-0.8], P = .007 and OR, 0.5 [95% CI, 0.3-0.9], P = .02, respectively). The haplotype analysis revealed that the maternal and placental TABf haplotype may lead to decreased risk of PE. In addition, the placental TABF haplotype was associated with higher risk of PE. No relationship was observed between PE susceptibility and the maternal and placental VDR Bsm1, Taq1 and Apa1 polymorphisms. There was also no relationship between the maternal and placental VDR polymorphisms and PE severity.Conclusions: the maternal and placental VDR FokI variant was associated with decreased risk of PE in the dominant model.

Association of pre-eclampsia with SOD2 Ala16Val polymorphism among mother-father-infant triads

OBJECTIVE

To determine whether pre-eclampsia is associated with polymorphisms in superoxide dismutase (SOD) genes among mother-father-infant triads.

METHODS

We did this follow-up cohort study at 17 urban hospitals in Canada between October 1, 2008, and September 30, 2010. We recruited Canadian participants who had participated in the International Trial of Antioxidant Supplementation for the Prevention of Pre-eclampsia. Saliva specimens were collected for DNA extraction. The SOD1 +35A/C (rs2234694) and SOD2 Ala16Val C/T (rs4880) single-nucleotide polymorphisms (SNPs) were genotyped.

RESULTS

Dual presence of the SOD2 Ala16Val TT variant among mother-father pairs (n=657) was associated with an increased risk of pre-eclampsia when compared with the absence of the TT variant among the mother-father pairs (7/48 [14.6%] vs 11/339 [3.2%]; adjusted odds ratio 6.80, 95% confidence interval 2.32-19.95; P<0.001). By contrast, presence of a single T variant in mother-father pairs (16/270 [5.9%]) or mother-infant pairs (8/179 [4.5%]) was not associated with pre-eclampsia. The SOD1 +35A/CSNP was not associated with pre-eclampsia.

CONCLUSION

The SOD2 Ala16Val SNP might be involved in paternal influence on the maternal predisposition to pre-eclampsia. Genotyping of mother-father pairs could be a promising strategy to identify pre-eclampsia genes.

Association study between GAS6 gene polymorphisms and risk of preeclampsia in Chinese population

CONTEXT AND OBJECTIVE

Preeclampsia is a pregnancy-specific disorder associated with pro-inflammatory and pro-thrombotic events. The growth arrest-specific 6 (GAS6) has been implicated in systemic inflammation and coagulation. Common genetic polymorphisms of GAS6 gene have previously been reported. The aim of this study was to investigate the association of GAS6 gene polymorphisms with the risk of preeclampsia in Chinese subjects.

STUDY DESIGN

The case-control population consists of 551 subjects. The genotyping of the single-nucleotide polymorphisms of GAS6 gene, GAS6 834 +7G/A(rs8191974) and +1332C/T (rs1803628), was carried out on genomic DNA using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) analysis.

RESULTS

There were significant differences in the +1332C/T genotype and allele frequencies between the patients with preeclampsia and the controls (P=0.03 and 0.02, respectively). The +1332 TT genotype was found to be protective from the development of preeclampsia (odds ratios 0.271, 95% confidence interval 0.077-0.953; P=0.03). Further analysis showed that the TT genotype of the GAS6 +1332C/T conferred a risk of severe preeclampsia (OR=0.597, 95% confidence interval 0.416-0.855; P=0.01). However, there were no differences in the 834+7G/A genotype and allele frequencies between the patients with preeclampsia and the controls.

CONCLUSION

Our data suggest that a TT genotype at +1332C/T polymorphism might be associated with decreased risk for preeclampsia, but the 834+7G/A polymorphism is not associated with the disorder, in the Chinese population.

FoxP3 gene promoter polymorphism affects susceptibility to preeclampsia

BACKGROUND

Preeclampsia (PE) is a multifactorial pregnancy disorder and is a major cause of maternal morbidity and mortality. Despite intense study, the pathophysiology of preeclampsia remains enigmatic. Recent studies have reported that regulatory T cells (Tregs) is linked with PE. It is well identified that FoxP3/Scurfin is involved in development and function of Tregs. However, the association between PE and the FoxP3 gene polymorphism has not been sufficiently investigated. In this study, we hypothesized that polymorphisms of the FoxP3 may be related to PE.

METHODS

We assessed the relationship between four single-nucleotide polymorphisms (SNPs) in the FoxP3 genes with sequence-specific primers (PCR-SSP) in 81 PE patients and 90 age-matched controls.

RESULT

We identified significant difference of rs4824747 GG genotype frequency between the PE and control groups. Women with GG genotypes exhibited higher (OR=6.25, 95% CI=2.63-14.85; P<0.0001) risk of developing PE. None of the other investigated SNPs (rs2232365, rs3761547 and rs3761548) showed significant association with PE.

CONCLUSION

We suggest that FoxP3 polymorphisms (rs4824747) could be a potential contributor for the development of PE in Iranian women.

Association study between GSTT1 and GSTM1 polymorphisms and risk of preeclampsia in Chinese population

CONTEXT AND OBJECTIVE

Preeclampsia is a pregnancy-specific disorder associated with oxidative stress. The glutathione S-transferases (GST) are a group of enzymes that protect cells from oxidative stress. Functional genetic polymorphisms of GST genes (GSTT1, GSTM1) have previously been reported. The aim of this study was to investigate the association of GST gene polymorphisms with the risk of preeclampsia in Chinese subjects.

STUDY DESIGN

The case-control population consists of 525 subjects. The genotyping of the GSTT1 and GSTM1 polymorphisms was carried out on genomic DNA using the multiplex polymerase chain reaction (PCR). We calculated odds ratios (ORs), adjusted for the confounding variables, to estimate the association between gene polymorphisms and preeclampsia.

RESULTS

The GSTT1 null genotype was found to be protective from the development of preeclampsia (odds ratios 0.645, 95% confidence interval 0.421-0.989; P=0.044). Further analysis showed that a combination of deletion genotypes of the GSTT1 and GSTM1 genes conferred an even lower risk of preeclampsia (OR=0.470, 95%CI=0.255-0.866; P=0.015). There is no relationship between the GSTT1 and GSTM1 gene polymorphisms and blood pressure levels in pregnant women with and without preeclampsia.

CONCLUSION

Our data suggest that a GSTT1 null polymorphism might be associated with decreased risk for preeclampsia in the Chinese population, and that this risk decreases with the combination of both GSTT1 and GSTM1 null polymorphisms.

Hypertensive disorders during monozygotic and dizygotic twin gestations: A population-based study

OBJECTIVE

To determine whether the incidence of hypertensive disorders is different in monozygotic compared to dizygotic twin pregnancies.

METHODS

A registry-based survey of twin pregnancies delivered during 2003 to 2012. We used the best clinical estimate of zygosity based on the concept that all monochorionic twins are monozygotic and all unlike-sex pairs are dizygotic, thus excluding same-sex dichorionic twin gestations for which zygosity cannot be ascertained on clinical grounds. Study cohorts were twin pregnancies with or without preeclampsia and gestational hypertension.

RESULTS

A total of 3419 twin gestations met the inclusion criteria, of which 442 (12.9%) were monochorionic and 1255 (36.7%) were unlike-sex twins, excluding 1722 same-sex dichorionic twin gestations (50.4%). There was no significant difference in the incidence of preeclampsia (OR: 0.9; 95% CI: 0.4-2.0 for monozygotic males and OR: 0.6; 95% CI: 0.3-1.4 for monozygotic females) and gestational hypertension (OR: 0.7; 95% CI: 0.2-2.5 for monozygotic males, and OR: 0.7; 95% CI: 0.2-2.3 for monozygotic females) between monochorionic and unlike-sex pairs. Maternal prepregnancy obesity and nulliparity were the only significant associated factors of preeclampsia (OR: 3.8; 95% CI: 2.0-7.0, and OR: 2.5; 95% CI: 1.4-4.4, respectively). Maternal prepregnancy obesity (OR: 5.5; 95% CI: 2.5-12.2), maternal age ≥36 years (OR: 2.5; 95% CI: 1.1-6.1), and family history of hypertension (OR: 2.6; 95% CI: 1.3-5.1) were significantly associated with gestational hypertension.

CONCLUSION

Based on a large population-based dataset and on the best clinical estimate of twin zygosity, it appears that zygosity is not associated with hypertensive disorders in twin gestations.

Pregnancy-Associated Heart Failure: A Comparison of Clinical Presentation and Outcome between Hypertensive Heart Failure of Pregnancy and Idiopathic Peripartum Cardiomyopathy

Aims

There is controversy regarding the inclusion of patients with hypertension among cases of peripartum cardiomyopathy (PPCM), as the practice has contributed significantly to the discrepancy in reported characteristics of PPCM. We sought to determine whether hypertensive heart failure of pregnancy (HHFP) (i.e., peripartum cardiac failure associated with any form of hypertension) and PPCM have similar or different clinical features and outcome.

Methods and Results

We compared the time of onset of symptoms, clinical profile (including electrocardiographic [ECG] and echocardiographic features) and outcome of patients with HHFP (n = 53; age 29.6 ± 6.6 years) and PPCM (n = 30; age 31.5 ± 7.5 years). The onset of symptoms was postpartum in all PPCM patients, whereas it was antepartum in 85% of HHFP cases (p<0.001). PPCM was more significantly associated with the following features than HHFP (p<0.05): twin pregnancy, smoking, cardiomegaly with lower left ventricular ejection fraction on echocardiography, and longer QRS duration, QRS abnormalities, left atrial hypertrophy, left bundle branch block, T wave inversion and atrial fibrillation on ECG. By contrast, HHFP patients were significantly more likely (p<0.05) to have a family history of hypertension, hypertension and pre-eclampsia in a previous pregnancy, tachycardia at presentation on ECG, and left ventricular hypertrophy on echocardiography. Chronic heart failure, intra-cardiac thrombus and pulmonary hypertension were found significantly more commonly in PPCM than in HHFP (p<0.05). There were 5 deaths in the PPCM group compared to none among HHFP cases (p = 0.005) during follow-up.

Conclusion

There are significant differences in the time of onset of heart failure, clinical, ECG and echocardiographic features, and outcome of HHFP compared to PPCM, indicating that the presence of hypertension in pregnancy-associated heart failure may not fit the case definition of idiopathic PPCM.

Polymorphisms of the methylenetetrahydrofolate reductase gene (C677T and A1298C) in the placenta of pregnancies complicated with preeclampsia

BACKGROUND

Preeclampsia has been related to single-nucleotide polymorphisms (SNPs) of the methylenetetrahydrofolate reductase (MTHFR) gene; however, data regarding the placenta are still lacking.

OBJECTIVE

To determine the frequency of C677T and A1298C SNPs of the MTHFR gene in the placenta of preeclamptic pregnancies and healthy controls.

METHODS

Genotyping of C677T and A1298C polymorphisms of the MTHFR gene using RFLP-PCR was performed to the placenta of 100 gestations (n = 50 complicated with preeclampsia and n = 50 normal controls matched for parity and maternal age).

RESULTS

Gestational age at birth and neonatal and placental weight were significantly lower in women with preeclampsia as compared to controls. The TT genotype of the C677T polymorphism was threefold more prevalent in preeclamptic placentas as compared to the placenta of controls (24.0% versus 8.0%, p = 0.001). Upon pooled analysis (n = 100), placental and neonatal weights were significantly lower in placentas displaying this genotype (TT, C677T) as compared with the CC genotype.

CONCLUSION

This study found that the frequency of the TT mutant genotype of the C677T polymorphism was higher in the placenta of pregnancies complicated with preeclampsia. There is a need for further research in this matter.

The Association of CARD8 rs2043211 Polymorphism with Preeclampsia in the Chinese Han Population

OBJECTIVE

The purpose of our study was to investigate the association between polymorphism of rs2043211 in CARD8 and susceptibility to preeclampsia (PE) in the Chinese Han population.

METHODS

261 PE patients and 451 controls were genotyped for rs2043211 with the method of TaqMan allele discrimination assays. Clinical data were collected to perform genotype-phenotype analysis.

RESULTS

Our study suggested that the rs2043211 variant was associated with the development of PE in the Chinese Han population. The genotypic and allelic frequencies differed significantly between the two groups (x03C7;2 = 8.198, p = 0.017 by genotype; x03C7;2 = 6.741, p = 0.009 by allele). The T allele was the risk allele for predisposition to PE (OR = 1.331, 95% CI 1.072-1.652).

CONCLUSION

The polymorphism of rs2043211 in CARD8 may be a relevant host susceptibility factor for the development of PE in the Chinese Han population.

Maternal/newborn VEGF-C936T interaction and its influence on the risk, severity and prognosis of preeclampsia, as well as on the maternal angiogenic profile

OBJECTIVE

To analyze the influence of maternal/newborn vascular endothelial growth factor (VEGF)-CT936 interaction as a modulating factor in preeclampsia as well as its influence on the maternal angiogenic balance.

METHODS

Seventy pairs of preeclamptic women/newborns and 94 pairs of normal pregnant mothers/newborns were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Serum VEGF and soluble VEGF receptor-1 (sVEGFR-1) levels were measured using ELISA.

RESULTS

The risk to develop mild (odds ratio; OR: 3.79, p = 0.008) and severe (OR: 2.94, p = 0.037) preeclampsia being increased in association with the CT936-VEGF genotype and increased in severe preeclampsia to 6.07 (p = 0.03) if the women were carriers of the homozygous TT936-VEGF genotype. The presence of the VEGF-T936 allele in both the mother and the newborn significantly increases the risk of pregnancy-induced hypertension (PIH), mild and severe preeclampsia. If both the mothers and newborns were carriers of the VEGF-T936 allele, significantly lower VEGF and higher sVEGFR-1 levels were observed for all types of preeclampsia. Pregnant women with PIH and severe preeclampsia delivered at a significantly earlier gestational age neonates with a significantly lower birth weight if both the preeclamptic mothers and their newborns were carriers of the VEGF-T936 allele.

CONCLUSIONS

Our study suggests the role of maternal/fetal VEGF-CT936 polymorphism as a modulating factor in preeclampsia, which affects the angiogenic balance in preeclamptic mothers, as well as their pregnancy outcome.

Abnormal oxidative stress responses in fibroblasts from preeclampsia infants

Background

Signs of severe oxidative stress are evident in term placentae of infants born to mothers with preeclampsia (PE), but it is unclear whether this is a cause or consequence of the disease. Here fibroblast lines were established from umbilical cords (UC) delivered by mothers who had experienced early onset PE and from controls with the goal of converting these primary cells to induced pluripotent stem cells and ultimately trophoblast. Contrary to expectations, the oxidative stress responses of these non-placental cells from PE infants were more severe than those from controls.

Methods and Findings

Three features suggested that UC-derived fibroblasts from PE infants responded less well to oxidative stressors than controls: 1) While all UC provided outgrowths in 4% O₂, success was significantly lower for PE cords in 20% O₂; 2) PE lines established in 4% O₂ proliferated more slowly than controls when switched to 20% O₂; 3) PE lines were more susceptible to the pro-oxidants diethylmaleate and tert-butylhydroquinone than control lines, but, unlike controls, were not protected by glutathione. Transcriptome profiling revealed only a few genes differentially regulated between PE lines and controls in 4% O₂ conditions. However, a more severely stressed phenotype than controls, particularly in the unfolded protein response, was evident when PE lines were switched suddenly to 20% O₂, thus confirming the greater sensitivity of the PE fibroblasts to acute changes in oxidative stress.

Conclusions

UC fibroblasts derived from PE infants are intrinsically less able to respond to acute oxidative stress than controls, and this phenotype is retained over many cell doublings. Whether the basis of this vulnerability is genetic or epigenetic and how it pertains to trophoblast development remains unclear, but this finding may provide a clue to the basis of the early onset, usually severe, form of PE.

Genetic variations in IL1A and IL1RN are associated with the risk of preeclampsia in Chinese Han population

Preeclampsia (PE) is an excessive systemic inflammation response with dysfunction of endothelial. Our study was to investigate the association between genetic variations in IL-1 and the susceptibility to PE in Chinese Han population. 402 PE patients and 554 normal pregnant women of third trimester were enrolled. The polymorphisms of rs315952 in IL1RN and rs17561 in IL1A were genotyped by TaqMan allelic discrimination real-time PCR. Obviously statistic difference of the genotypic frequencies were found in both of IL1RN rs315952 and IL1A rs17561 between cases and controls (for rs315952, P = 0.001; for rs17561, P = 0.021.). For rs315952, the C allele was associated with development of PE (P = 0.003, OR = 1.319, 95%CI 1.099–1.583). Patients with CC or CT genotype were less likely to develop severe PE than patients carrying TT genotype(P< 0.001, OR = 0.24, 95%CI 0.15–0.40). For rs17561, the C allele was the risk factor for predisposition to PE (P = 0.012, OR = 1.496, 95%CI 1.089–2.055). Our results suggest IL1RN and IL1A may involve in the development of PE in Chinese Han population.

Possible association of IL-4 VNTR polymorphism with susceptibility to preeclampsia

Preeclampsia (PE) is a pregnancy-specific disorder that results in maternal mortality and morbidity. Growing evidence indicated that cytokines are involved in the pathogenesis of PE and interleukin-4 VNTR polymorphism could be implicated in altering the PE risk. The aim of this study was to evaluate the possible association between IL-4 VNTR polymorphism and susceptibility to PE in Iranian population for the first time. Genetic polymorphism was evaluated in 192 PE and 186 healthy control women by polymerase chain reaction method. We found that the VNTR polymorphism of IL-4 gene has significantly increased the risk of preeclampsia (RP2/RP1 versus RP1/RP1, OR, 2.8 [95% CI, 1.7 to 8.8]; P = 0.0001 and RP2/RP2 versus RP1/RP1; P = 0.002). The results showed that carriage of IL-4 VNTR RP2 allele has positive association with preeclampsia susceptibility.

Why preeclampsia still exists?

Preeclampsia (PE) is a deadly gestational disease affecting up to 10% of women and specific of the human species. Preeclampsia is clearly multifactorial, but the existence of a genetic basis for this disease is now clearly established by the existence of familial cases, epidemiological studies and known predisposing gene polymorphisms. PE is very common despite the fact that Darwinian pressure should have rapidly eliminated or strongly minimized the frequency of predisposing alleles. Consecutive pregnancies with the same partner decrease the risk and severity of PE. Here, we show that, due to this peculiar feature, preeclampsia predisposing-alleles can be differentially maintained according to the familial structure. Thus, we suggest that an optimal frequency of PE-predisposing alleles in human populations can be achieved as a result of a trade-off between benefits of exogamy, importance for maintaining genetic diversity and increase of the fitness owing to a stable paternal investment.

Association between Val158Met functional polymorphism in the COMT gene and risk of preeclampsia in a Chinese population

BACKGROUND AND AIMS

The catechol-O-methyltransferase (COMT) gene is a potential candidate in altering risk for preeclampsia due to the important enzymatic effects in the metabolism of steroid hormones. It contains a non-synonymous G-A base change at codon 158 in the membrane bound isoform, which leads to a valine-to-methionine amino acid substitution. In the soluble isoform the polymorphism rs4680 is located in codon 108. The variant allele is the Met (A) allele and the Val (G) allele is the wild type allele. Despite its previously reported association with preeclampsia in genotypes in three selected ethnic groups, further studies in other populations are required.

METHODS

We genotyped the Val158Met polymorphism in the COMT gene by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) analysis in a Chinese population.

RESULTS

In the case-control study that included 187 patients with preeclampsia (cases) and 189 normal subjects (controls), the AA genotype and variant Met allele frequencies of Val158Met in the COMT gene were significantly higher in patients with preeclampsia than those in the control group (both p <0.05). The odds ratio for the risk of preeclampsia was 2.395 [95% confidence interval (CI): 1.061-5.408] in women homozygous for the variant COMT allele (χ(2) = 4.649, p = 0.031). Furthermore, it showed that obese women homozygous for the variant COMT allele (Met/Met) had higher diastolic blood pressure levels during pregnancy than wild-type homozygotes (Val/Val) (p = 0.034).

CONCLUSIONS

Our study provided evidence in favor of COMT being a candidate gene for conferring genetic susceptibility to preeclampsia in a South West Chinese population.

Angiotensin converting enzyme insertion/deletion polymorphism and risk of pregnancy hypertensive disorders: a meta-analysis

BACKGROUND

The angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism has been reported inconsistently as being associated with risk of pregnancy hypertensive disorders (PHDs). We examined these associations by performing a meta-analysis.

METHODS

Two investigators independently consulted the Medline, Embase, CNKI, and Chinese Biomedicine databases. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated in fixed- and random-effects models when appropriate. Subgroup analyses were performed by ethnicity, types of PHD (gestational hypertension, pre-eclampsia and eclampsia), country and Hardy-Weinberg equilibrium (HWE) in controls.

RESULTS

This meta-analysis included 30 case-control studies with 3523 cases and 4817 controls. Overall, we found that the DD variant of the ACE I/D polymorphism was associated with a significantly increased PHD risk. In the subgroup analysis by ethnicity, the results suggested that the DD genotype was significantly associated with risk of PHD development among Asians and Caucasians. Moreover, when stratifying by types of PHD, a significantly increased risk was observed for pre-eclampsia. Interestingly, when stratifying by country, a significantly elevated risk was found among 'others' countries (those that were not China or Korea). Limiting the analysis to the studies within HWE, the results were persistent and robust.

CONCLUSION

This meta-analysis suggests that the I/D polymorphism of ACE may be associated with PHD risk, especially among Asians and Caucasians.

Placental expression of angiogenic factors in Trisomy 13

OBJECTIVE

Increased levels of soluble fms-like tyrosine kinase (sFlt-1) in Trisomy 13 pregnancies are thought to be mediated by the placenta. This study aimed to compare sFlt-1 expression in Trisomy 13 (n = 7) placentas with that in control placentas (Trisomy 21, n = 11, and euploid, n = 6).

STUDY DESIGN

This was a retrospective case-control study analyzing paraffin-embedded placental blocks that were stained with hematoxylin and eosin and antibodies to sFlt-1. Their staining intensity was compared using a semiquantitative technique. The Kruskal-Wallis test and Wilcox rank sum test were used for statistical analysis.

RESULTS

The median staining was significantly higher in Trisomy 13 compared with control specimens (P = .008) (for Trisomy 13 vs Trisomy 21, P = .003, and Trisomy 13 vs euploid, P = .004).

CONCLUSION

Our study demonstrates that Trisomy 13 placentas express more sFlt-1 than control placentas. These results strengthen the hypothesis that the increased incidence of preeclampsia in Trisomy 13 pregnancies is secondary to placental up-regulation of sFlt-1.

Regulation of pregnancy-associated plasma protein A2 (PAPPA2) in a human placental trophoblast cell line (BeWo)

BACKGROUND

Pregnancy-associated plasma protein A2 (PAPPA2) is an insulin-like growth factor-binding protein (IGFBP) protease expressed at high levels in the placenta and upregulated in pregnancies complicated by preeclampsia and HELLP (Hemolytic anemia, Elevated Liver enzymes, and Low Platelet count) syndrome. However, it is unclear whether elevated PAPPA2 expression causes abnormal placental development, or whether upregulation compensates for placental pathology. In the present study, we investigate whether PAPPA2 expression is affected by hypoxia, oxidative stress, syncytialization factors or substances known to affect the expression of PAPPA2's paralogue, PAPPA.

METHODS

BeWo cells, a model of placental trophoblasts, were treated with one of the following: hypoxia (2% O2), oxidative stress (20 microM hydrogen peroxide), forskolin (10 microM and 100 microM), TGF-beta (10 and 50 ng/mL), TNF-alpha (100 ng/mL), IL-1beta (100 ng/mL) or PGE2 (1 microM). We used quantitative RT-PCR (qRT-PCR) to quantify the mRNA levels of PAPPA2, as well as those of PAPPA and ADAM12 since these proteases have similar substrates and are also highly expressed in the placenta. Where we observed significant effects on PAPPA2 mRNA levels, we tested for effects at the protein level using an in-cell Western assay.

RESULTS

Hypoxia, but not oxidative stress, caused a 47-fold increase in PAPPA2 mRNA expression, while TNF-alpha resulted in a 6-fold increase, and both of these effects were confirmed at the protein level. PGE2 resulted in a 14-fold upregulation of PAPPA2 mRNA but this was not reflected at the protein level. Forskolin, TGF-beta and IL-1beta had no significant effect on PAPPA2 mRNA expression. We observed no effects of any treatment on PAPPA or ADAM12 expression.

CONCLUSION

Our study demonstrates that factors previously known to be highly expressed in preeclamptic placentae (PGE2 and TNF-alpha), contribute to the upregulation of PAPPA2. Hypoxia, known to occur in preeclamptic placentae, also increased PAPPA2 expression. These results are consistent with the hypothesis that PAPPA2 is upregulated as a consequence of placental pathology, rather than elevated PAPPA2 levels being a cause of preeclampsia.

Genetic variation in solute carrier genes is associated with preeclampsia

OBJECTIVE

The objective of the study was to evaluate allelic variation in 26 members of the solute carrier (SLC) gene family for an association with preeclampsia.

STUDY DESIGN

Preeclampsia cases were women with mild or severe preeclampsia. Controls were enrolled from women without hypertension-related complications who presented for delivery at term (≥37 weeks). The association between preeclampsia and SLC gene single-nucleotide polymorphisms (SNPs) and haplotypes was evaluated by logistic regression models.

RESULTS

Rs4957061 in SLC9A3 was significantly associated with a reduced risk of preeclampsia in whites (T allele, P = .002; odds ratio [OR], 0.33; 95% confidence interval [CI], 0.16-0.67). For SLC4A1 in blacks, the G allele of rs2074107 (P = .004; OR, 1.56; 95% CI, 1.15-2.12) and the A allele of rs2857078 (P < .001; OR, 1.67; 95% CI, 1.27-2.17) were significantly associated with preeclampsia. Also in blacks, rs10066650 in SLCO4C1 (G allele, P = .002; OR, 1.72; 95% CI, 1.21-2.46) was significantly associated with increased risk. Sliding window haplotype analyses identified significantly associated haplotypes in these genes.

CONCLUSION

SNPs and haplotypes in SLC9A3 in whites and SLC4A1 and SLCO4C1 in blacks are significantly associated with preeclampsia.

Variable effects of maternal and paternal-fetal contribution to the risk for preeclampsia combining GSTP1, eNOS, and LPL gene polymorphisms

Objective

To evaluate the maternal, paternal, and fetal genotype contribution to preeclampsia.

Study design, materials, and methods

We combined the analysis of polymorphisms of the GSTP1, eNOS, and LPL genes – affecting biotransformation enzymes and endothelial function – in a cohort of 167 preeclamptic and normal control trios (mother, father, and child) comprising a total of 501 samples in the Greek population, never analyzed before by this approach.

Results

For the frequency of the GSTP1 Ile¹⁰⁵/Val¹⁰⁵, the eNOS Glu298Asp and the LPL-93 polymorphisms, statistically significant differences were found between the two groups. However, the transmission rates of the parental alleles to neonates studied by the transmission disequilibrium test, disclosed no increased rate of transmission to preeclampsia children for the variant alleles of Val¹⁰⁵ GSTP1, 298Asp eNOS, and -93G LPL.

Conclusions

These novel data, suggest that interaction of all three types of genotypes (mother, father and neonate), reveals no effects on the development of preeclampsia, but provide the impetus for further studies to decipher the individual contribution of each genetic parameter of preeclampsia.

Altered placental expression of PAPPA2 does not affect birth weight in mice

BACKGROUND

Pregnancy-associated plasma protein A2 (PAPPA2) is an insulin-like growth factor binding protein (IGFBP) protease expressed in the placenta and upregulated in pregnancies complicated by pre-eclampsia. The mechanism linking PAPPA2 expression and pre-eclampsia and the consequences of altered PAPPA2 expression remain unknown. We previously identified PAPPA2 as a candidate gene for a quantitative trait locus (QTL) affecting growth in mice and in the present study examined whether this QTL affects placental PAPPA2 expression and, in turn, placental or embryonic growth.

METHODS

Using a line of mice that are genetically homogenous apart from a 1 megabase QTL region containing the PAPPA2 gene, we bred mice homozygous for alternate QTL genotypes and collected and weighed placentae and embryos at E12.5. We used quantitative RT-PCR to measure the mRNA levels of PAPPA2, as well as mRNA levels of IGFBP-5 (PAPPA2's substrate), and PAPPA (a closely related IGFBP protease) to examine potential feedback and compensation effects. Western blotting was used to quantify PAPPA2 protein. Birth weight was measured in pregnancies allowed to proceed to parturition.

RESULTS

PAPPA2 mRNA and protein expression levels in the placenta differed by a factor of 2.5 between genotypes, but we did not find a significant difference between genotypes in embryonic PAPPA2 mRNA levels. Placental IGFBP-5 and PAPPA mRNA expression levels were not altered in response to PAPPA2 levels, and we could not detect IGFBP-5 protein in the placenta by Western blotting. The observed difference in placental PAPPA2 expression had no significant effect on placental or embryonic mass at mid-gestation, birth weight or litter size.

CONCLUSIONS

Despite a significant difference between genotypes in placental PAPPA2 expression similar in magnitude to the difference between pre-eclamptic and normal placentae previously reported, we observed no difference in embryonic, placental or birth weight. Our results suggest that elevated PAPPA2 levels are a consequence, rather than a cause, of pregnancy complications.

Allelic variations in angiogenic pathway genes are associated with preeclampsia

OBJECTIVE

This study investigates the association of allelic variation in angiogenic pathway genes and preeclampsia.

STUDY DESIGN

Data for cases with preeclampsia and term control subjects were collected prospectively. Maternal DNA was extracted, and 124 tagging single nucleotide polymorphisms in 6 genes (vascular endothelial growth factor A, B, and C; fms-like tyrosine kinase 1 and 4; endoglin) were genotyped. Multivariable logistic regression was used to evaluate the association between tagging single nucleotide polymorphisms and preeclampsia; data were controlled for age. All models were evaluated in black women and white women separately. Haplotype analyses were performed.

RESULTS

We analyzed data from 606 women (489 black women [184 cases] and 117 white women [32 cases]). In black women, the fms-like tyrosine kinase 1 rs12584067 (odds ratio [OR], 1.55; 95% confidence interval [CI], 1.01-2.36; P=.05) and rs7335588 (OR, 1.61; 95% CI, 1.06-2.43; P=.01) and the vascular endothelial growth factor C rs1485766 (OR, 1.56; 95% CI, 1.05-2.30; P=.03) and rs6838834 (OR, 1.60; 95% CI, 1.05-2.45; P=.03) single nucleotide polymorphisms were associated with preeclampsia. In white women, the fms-like tyrosine kinase 1 rs722503 (OR, 2.12; 95% CI, 1.07-4.19; P=.03), fms-like tyrosine kinase 4 rs307826 (OR, 3.06; 95% CI, 1.18-7.91; P=.01), and vascular endothelial growth factor C rs7664413 (OR, 2.04; 95% CI, 0.99-4.17; P=.04) single nucleotide polymorphisms were associated with preeclampsia.

CONCLUSION

Allelic variations in the fms-like tyrosine kinase 1 and vascular endothelial growth factor C genes are associated with preeclampsia in both ethnic groups.

Gene expression profiling of placentas affected by pre-eclampsia

Several studies point to the placenta as the primary cause of pre-eclampsia. Our objective was to identify placental genes that may contribute to the development of pre-eclampsia. RNA was purified from tissue biopsies from eleven pre-eclamptic placentas and eighteen normal controls. Messenger RNA expression from pooled samples was analysed by microarrays. Verification of the expression of selected genes was performed using real-time PCR. A surprisingly low number of genes (21 out of 15,000) were identified as differentially expressed. Among these were genes not previously associated with pre-eclampsia as bradykinin B1 receptor and a 14-3-3 protein, but also genes that have already been connected with pre-eclampsia, for example, inhibin beta A subunit and leptin. A low number of genes were repeatedly identified as differentially expressed, because they may represent the endpoint of a cascade of events effectuated throughout gestation. They were associated with transcriptional regulation and vasoregulative pathways, along with a number of hypothetical proteins and gene sequences with unknown functions.

Genetic variation in the indoleamine 2,3-dioxygenase gene in pre-eclampsia

PROBLEM

To investigate the contribution of genomic variations in the indoleamine 2,3-dioxygenase (IDO) gene to the onset of pre-eclampsia.

METHOD OF STUDY

We examined sequence variations in the IDO1 gene using placental genomic DNA from 35 pre-eclamptic patients and 32 normotensive pregnant women.

RESULTS

A case-control study revealed that none of the common variants influences the risk of disease. Sequencing of each IDO1 exon in diseased subjects revealed rare variants. This variation, c.-147_150delGAAA, was located within the 5'-untranslated region of the IDO1 gene, and its homozygote was identified only in pre-eclamptic subjects. However, despite the low levels of IDO expression and enzyme activity in the c.-147_150delGAAA homozygote, reporter assays indicated that this variation does not affect gene expression.

CONCLUSION

Our findings indicate that genetic alteration of fetal IDO gene does not appear to be a primary cause of pre-eclampsia.

The origin of pre-eclampsia: from decidual "hyperoxia" to late hypoxia

Normal gestation implants on a relatively hypoxic deciduas so that trophoblast deeply invades endometrium and angiogenesis seeks for oxygen supply. If implantation occurs before those hypoxic conditions occur, trophoblast invasion is defective, due to the relatively high oxygen tension in the decidual environment, laying the foundations for subsequent pre-eclampsia.