Cohort profile: the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC)

Impact of physical activity on preeclampsia and angiogenic markers in the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort

INTRODUCTION

Effect of physical activity in pregnancy on preeclampsia (PE) and angiogenic markers is not well understood. We studied the association of physical activity and PE in a case-control setting and assessed whether exercise in PE and non-PE women associate with maternal serum concentrations of soluble fms-like tyrosine kinase 1 (s-Flt-1), placental growth factor (PlGF) and soluble endoglin (sEng) and sFlt-1/PlGF ratio in the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort.

MATERIALS AND METHODS

Participants completed a questionnaire on their background information and serum samples were collected from a subset. Questionnaire data on physical activity were available from 708 PE women and 724 non-PE women. Both first trimester serum samples and questionnaire data on physical activity were available from 160 PE women and 160 non-PE women, and second/third trimester serum samples and questionnaire data on physical activity were available from 139 PE women and 47 non-PE women. The PE and non-PE women were divided into categories of physically active (exercise 2 - 3 times/week or more) and physically inactive (exercise less than 2 - 3 times/week).

RESULTS

A total of 43.4% of the PE women and 42.4% of the non-PE women were categorized as physically active. There were no differences in physical activity and exercise habits between the groups. The physically active women were more often nulliparous and non-smokers and had a lower body mass index. There were no differences in the concentrations of angiogenic markers (sFlt-1, PlGF and sEng and sFlt-1/PlGF ratio) between the groups who exercised more or less than 2 - 3 times/week.

CONCLUSIONS

In the FINNPEC study cohort, there was no association between physical activity and PE and no associations of physical activity in pregnant women with and without PE with maternal serum concentrations of sFlt-1, PlGF and sEng and sFlt-1/PlGF ratio.

Delayed versus early delivery leads to similar outcome in selected cases of preeclampsia in the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort

OBJECTIVES

Most guidelines recommend induction of labor after 37 weeks of gestation in preeclampsia. This study assessed the effect of interval between diagnosis of preeclampsia and delivery on maternal and perinatal outcomes.

STUDY DESIGN

A cohort of 1637 women with preeclampsia recruited at five university hospitals in Finland was studied. Outcomes were compared in two groups according to the time interval between diagnosis of PE and delivery: delivery in less than 10 days (the early delivery group) and delivery at 10 days or later after the diagnosis (the delayed delivery group).

MAIN OUTCOME MEASURES

Maternal outcomes included significantly preterm delivery (delivery before 34 weeks of gestation), placental abruption, eclampsia and maternal intensive care or intensive monitoring for more than 24 h. Neonatal outcomes included small for gestational age, Apgar score of less than seven at the age of five minutes, umbilical artery pH < 7.05 and fetal death.

RESULTS

No differences in frequency of preterm deliveries or maternal need for intensive care were observed between groups. Eclampsia and fetal death were rare, and their incidence did not differ between the groups. No maternal deaths were observed. Low Apgar score at five minutes of age was reported more commonly in the early delivery group, but there was no difference in fetal acidemia between groups.

CONCLUSION

Early and delayed delivery lead to comparable outcomes in this cohort. Expectant management could be beneficial in women with an unripe cervix or preterm preeclampsia without severe features.

Rare variants in genes coding for components of the terminal pathway of the complement system in preeclampsia

Preeclampsia is a common multifactorial disease of pregnancy. Dysregulation of the complement activation is among emerging candidates responsible for disease pathogenesis. In a targeted exomic sequencing study we identified 14 variants within nine genes coding for components of the membrane attack complex (MAC, C5b-9) that are associated with preeclampsia. We found two rare missense variants in the C5 gene that predispose to preeclampsia (rs200674959: I1296V, OR (CI95) = 24.13 (1.25-467.43), p-value = 0.01 and rs147430470: I330T, OR (CI95) = 22.75 (1.17-440.78), p-value = 0.01). In addition, one predisposing rare variant and one protective rare variant were discovered in C6 (rs41271067: D396G, OR (CI95) = 2.93 (1.18-7.10), p-value = 0.01 and rs114609505: T190I, 0.02 OR (CI95) = 0.47 (0.22-0.92), p-value = 0.02). The results suggest that variants in terminal complement pathway predispose to preeclampsia.

Machine learning-enabled maternal risk assessment for women with pre-eclampsia (the PIERS-ML model): a modelling study

BACKGROUND

Affecting 2-4% of pregnancies, pre-eclampsia is a leading cause of maternal death and morbidity worldwide. Using routinely available data, we aimed to develop and validate a novel machine learning-based and clinical setting-responsive time-of-disease model to rule out and rule in adverse maternal outcomes in women presenting with pre-eclampsia.

METHODS

We used health system, demographic, and clinical data from the day of first assessment with pre-eclampsia to predict a Delphi-derived composite outcome of maternal mortality or severe morbidity within 2 days. Machine learning methods, multiple imputation, and ten-fold cross-validation were used to fit models on a development dataset (75% of combined published data of 8843 patients from 11 low-income, middle-income, and high-income countries). Validation was undertaken on the unseen 25%, and an additional external validation was performed in 2901 inpatient women admitted with pre-eclampsia to two hospitals in south-east England. Predictive risk accuracy was determined by area-under-the-receiver-operator characteristic (AUROC), and risk categories were data-driven and defined by negative (-LR) and positive (+LR) likelihood ratios.

FINDINGS

Of 8843 participants, 590 (6·7%) developed the composite adverse maternal outcome within 2 days, 813 (9·2%) within 7 days, and 1083 (12·2%) at any time. An 18-variable random forest-based prediction model, PIERS-ML, was accurate (AUROC 0·80 [95% CI 0·76-0·84] vs the currently used logistic regression model, fullPIERS: AUROC 0·68 [0·63-0·74]) and categorised women into very low risk (-LR <0·1; eight [0·7%] of 1103 women), low risk (-LR 0·1 to 0·2; 321 [29·1%] women), moderate risk (-LR >0·2 and +LR <5·0; 676 [61·3%] women), high risk (+LR 5·0 to 10·0, 87 [7·9%] women), and very high risk (+LR >10·0; 11 [1·0%] women). Adverse maternal event rates were 0% for very low risk, 2% for low risk, 5% for moderate risk, 26% for high risk, and 91% for very high risk within 48 h. The 2901 women in the external validation dataset were accurately classified as being at very low risk (0% with outcomes), low risk (1%), moderate risk (4%), high risk (33%), or very high risk (67%).

INTERPRETATION

The PIERS-ML model improves identification of women with pre-eclampsia who are at lowest and greatest risk of severe adverse maternal outcomes within 2 days of assessment, and can support provision of accurate guidance to women, their families, and their maternity care providers.

FUNDING

University of Strathclyde Diversity in Data Linkage Centre for Doctoral Training, the Fetal Medicine Foundation, The Canadian Institutes of Health Research, and the Bill & Melinda Gates Foundation.

Validation of the Finnish Care register for Health Care diagnoses for preeclampsia, gestational diabetes and preterm delivery

BACKGROUND

Centrally collected Finnish national health register data on adverse pregnancy outcomes are available for research, but the validity of the data is largely unknown. Our aim was to compare the diagnoses of preeclampsia (PE), gestational diabetes (GDM), and preterm delivery from hospital records with the registry based diagnoses from the Finnish Care Register for Health Care (FCR). Data on gestational age at delivery from the Medical Birth Registry (MBR) was also studied.

METHODS

The Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) Study cohort was used as a data source. Each diagnosis was ascertained from electronic hospital records. The validity of diagnoses obtained by record linkage of FCR and MBR was assessed against the classification previously confirmed independently by a research nurse and a study physician.

RESULTS

Sensitivity of PE diagnoses in FCR was 80.3 % (95 % CI 78.3 % to 82.2 %) andspecificity 95.3 % (95 % CI 93.9 % to 96.4 %). Sensitivity for GDM was 64.1 % (95 % CI: 58.7 % - 69.3 %) and specificity 98.5 % (95 % CI: 97.9 % - 98.9 %), whereas sensitivity and specificity for preterm delivery were 32.4 % (95 % CI: 29.0 % - 36.0 %) and 99.7 % (95 % CI: 99.3 % - 99.9 %). Sensitivity of preterm delivery in the MBR was 99.1 % and specificity 99.9 %.

CONCLUSIONS

FCR registry diagnoses for PE have satisfactory sensitivity and high specificity. Diagnoses for GDM and preterm delivery have lower sensitivity limiting their use in studies, and data from MBR should be preferred when studying preterm deliveries.

Hypertensive pregnancy complications and maternal characteristics as predictors of cardiovascular health within ten years after delivery

OBJECTIVE

To identify the combination of maternal characteristics in women with hypertensive disorders of pregnancy (HDP) associated with hypertensive and other cardiovascular diseases (CVDs) within ten years following delivery. The aim is to understand who should receive the most intensive primary cardiovascular disease prevention.

STUDY DESIGN

A prospective cohort study.

MAIN OUTCOME

The population was the FINNPEC cohort (2008-2011), including women with (n = 1837) and without (n = 847) HDP. The main exposures were maternal hypertensive pregnancy complications linked with maternal pregnancy data from hospital records. The outcomes were hypertensive diseases and other CVDs (International Classification of Diseases, Tenth Revision).

RESULTS

Women with de novo pre-eclampsia (PE) had an elevated risk for hypertensive diseases within ten years following delivery. The risk of CVD was increased in women with superimposed PE and chronic hypertension (CHT) only. Women with de novo PE and hypertensive diseases were more often primiparous (41.4% vs. 23.0%, p = 0.020), had gestational diabetes (GDM) (31.0% vs. 11.7%, p = 0.002), and higher pre-pregnancy body mass index (BMI) (28.7 ± 5.8 vs. 24.6 ± 4.8 kg/m2, p = 0.001), compared with women who remained normotensive. Women with superimposed PE with CVD had more likely early-onset PE, preterm delivery and were older than women without later CVD.

CONCLUSIONS

Healthcare professionals should target early prevention of CVDs in women with chronic hypertension during pregnancy; of those who developed superimposed PE prior to 34th weeks of gestation and who delivered preterm. Women with de novo PE who are overweight/obese, primiparous, and with concurrent GDM need regular blood pressure monitoring.

Identification of complement factor H variants that predispose to pre-eclampsia: A genetic and functional study

OBJECTIVE

The objective of the study was to investigate the role of genetic variants in complement proteins in pre-eclampsia.

DESIGN

In a case-control study involving 609 cases and 2092 controls, five rare variants in complement factor H (CFH) were identified in women with severe and complicated pre-eclampsia. No variants were identified in controls.

SETTING

Pre-eclampsia is a leading cause of maternal and fetal morbidity and mortality. Immune maladaptation, in particular, complement activation that disrupts maternal-fetal tolerance leading to placental dysfunction and endothelial injury, has been proposed as a pathogenetic mechanism, but this remains unproven.

POPULATION

We genotyped 609 pre-eclampsia cases and 2092 controls from FINNPEC and the national FINRISK cohorts.

METHODS

Complement-based functional and structural assays were conducted in vitro to define the significance of these five missense variants and each compared with wild type.

MAIN OUTCOME MEASURES

Secretion, expression and ability to regulate complement activation were assessed for factor H proteins harbouring the mutations.

RESULTS

We identified five heterozygous rare variants in complement factor H (L3V, R127H, R166Q, C1077S and N1176K) in seven women with severe pre-eclampsia. These variants were not identified in controls. Variants C1077S and N1176K were novel. Antigenic, functional and structural analyses established that four (R127H, R166Q, C1077S and N1176K) were deleterious. Variants R127H and C1077S were synthesised, but not secreted. Variants R166Q and N1176K were secreted normally but showed reduced binding to C3b and consequently defective complement regulatory activity. No defect was identified for L3V.

CONCLUSIONS

These results suggest that complement dysregulation due to mutations in complement factor H is among the pathophysiological mechanisms underlying severe pre-eclampsia.

Determinants of vascular structure and function in at-risk children born to mothers managed for pre-eclampsia (FINNCARE study)

Background and aim

Pre-eclampsia (PE) is related to elevated blood pressure (BP) in children. The study aims to investigate if elevated BP is reflected in child arterial health and how anthropometrics, body composition, and gestational and perinatal factors influenced this.

Methods

In this prospective cohort study, we assessed the arteries of 182 children exposed (46 had an early onset, with a diagnosis before 34 gestational weeks, and 136 had a late onset) and 85 children unexposed (non-PE) to PE at 8-12 years from delivery using ultra-high-frequency ultrasound in addition to ambulatory and central BPs, body composition and anthropometrics, and tonometry-derived pulse wave velocity (PWV).

Results

No differences were found in intima-media thickness (IMT), adventitia thickness (AT), lumen diameter (LD), local carotid artery stiffness, distensibility, or wall stress between PE-exposed and non-PE-exposed children. All children's brachial, radial, and femoral artery IMTs were associated with 24-h systolic BP (SBP) and pulse pressure, carotid-femoral PWV, and anthropometric measures. The 24-h SBP and anthropometrics, notably lean body mass, were independent predictors of peripheral artery IMTs (brachial R2 = 0.217, radial R2 = 0.208, femoral R2 = 0.214; p < 0.001). Head circumference predicted carotid artery IMT and LD (β = 0.163, p = 0.009; β = 0.417, p < 0.001, respectively), but carotid artery IMT was not associated with BP. No independent associations were found for peripheral artery ATs. Local carotid artery stiffness, distensibility, and wall stress were independently associated with adiposity. No significant associations were found between gestational or perinatal factors and child vascular health parameters.

Conclusions

The peripheral artery IMT of PE-exposed children is identical to that of non-PE-exposed children, but associated with BP. Adiposity is related to local carotid artery stiffness. These adverse associations in arterial health may reflect the early progression of cardiovascular disease in PE-exposed children.

Blood pressure, arterial stiffness, and cardiovascular risk profiles in 8-12-year-old children following preeclampsia (FINNCARE-study)

OBJECTIVES

The aim was to study if children following preeclampsia (PE) develop alterations in blood pressure (BP) and arterial stiffness already early in life, and how this is associated with gestational, perinatal and child cardiovascular risk profiles.

METHODS

One hundred eighty-two PE (46 early-onset with diagnosis before 34 gestational weeks, and 136 late-onset) and 85 non-PE children were assessed 8-12 years from delivery. Office and 24-h ambulatory BP, body composition, anthropometrics, lipids, glucose, inflammatory markers, and tonometry-derived pulse wave velocity (PWV) and central BPs were assessed.

RESULTS

Office BP, central BPs, 24-h systolic BP (SBP) and pulse pressure (PP) were higher in PE compared with non-PE. Early-onset PE children had the highest SBP, SBP-loads, and PP. SBP nondipping during night-time was common among PE. The higher child 24-h mean SBP among PE was explained by maternal SBP at first antenatal visit and prematurity (birth weight or gestational weeks), but child 24-h mean PP remained related with PE and child adiposity after adjustments. Central and peripheral PWVs were elevated in late-onset PE subgroup only and attributed to child age and anthropometrics, child and maternal office SBP at follow-up, but relations with maternal antenatal SBPs and prematurity were not found. There were no differences in body anthropometrics, composition, or blood parameters.

CONCLUSIONS

PE children develop an adverse BP profile and arterial stiffness early in life. PE-related BP is related with maternal gestational BP and prematurity, whereas arterial stiffness is determined by child characteristics at follow-up. The alterations in BP are pronounced in early-onset PE.Clinical Trial Registration information: https://clinicaltrials.gov/ct2/show/NCT04676295ClinicalTrials.gov Identifier: NCT04676295.

Increased Risk of Preeclampsia in Women With a Genetic Predisposition to Elevated Blood Pressure

BACKGROUND

Preeclampsia causes significant maternal and perinatal morbidity. Genetic factors seem to affect the onset of the disease. We aimed to investigate whether the polygenic risk score for blood pressure (BP; BP-PRS) is associated with preeclampsia, its subtypes, and BP values during pregnancy.

METHODS

The analyses were performed in the FINNPEC study (Finnish Genetics of Pre-Eclampsia Consortium) cohort of 1514 preeclamptic and 983 control women. In a case-control setting, the data were divided into percentiles to compare women with high BP-PRS (HBP-PRS; >95th percentile) or low BP-PRS (≤5th percentile) to others. Furthermore, to evaluate the effect of BP-PRS on BP, we studied 3 cohorts: women with preeclampsia, hypertensive controls, and normotensive controls.

RESULTS

BP values were higher in women with HBP-PRS throughout the pregnancy. Preeclampsia was more common in women with HBP-PRS compared with others (71.8% and 60.1%, respectively; P=0.009), and women with low BP-PRS presented with preeclampsia less frequently than others (44.8% and 61.5%, respectively; P<0.001). HBP-PRS was associated with an increased risk for preeclampsia (odds ratio, 1.7 [95% CI, 1.1-2.5]). Furthermore, women with HBP-PRS presented with recurrent preeclampsia and preeclampsia with severe features more often.

CONCLUSIONS

Our results suggest that HBP-PRS is associated with an increased risk of preeclampsia, recurrent preeclampsia, and preeclampsia with severe features. Furthermore, women with HBP-PRS present higher BP values during pregnancy. The results strengthen the evidence pointing toward the role of genetic variants associated with BP regulation in the etiology of preeclampsia, especially its more severe forms.

Circulating Levels of Anti-C1q and Anti-Factor H Autoantibodies and Their Targets in Normal Pregnancy and Preeclampsia

Preeclampsia (PE) generally manifests in the second half of pregnancy with hypertension and proteinuria. The understanding of the origin and mechanism behind PE is incomplete, although there is clearly an immune component to this disorder. The placenta constitutes a complicated immune interface between fetal and maternal cells, where regulation and tolerance are key. Stress factors from placental dysfunction in PE are released to the maternal circulation evoking the maternal response. Several complement factors play a role within this intricate landscape, including C1q in vascular remodeling and Factor H (FH) as the key regulator of alternative pathway complement activation. We hypothesize that decreased levels of C1q or FH, or disturbance of their function by autoantibodies, may be associated with PE. Autoantibodies against C1q and FH and the concentrations of C1q and FH were measured by ELISA in maternal sera from women with preeclamptic and normal pregnancies. Samples originated from cohorts collected in the Netherlands (n=63 PE; n=174 control pregnancies, n=51 nonpregnant), Finland (n=181 PE; n=63 control pregnancies) and Norway (n=59 PE; n=27 control pregnancies). Serum C1q and FH concentrations were higher in control pregnancy than in nonpregnant women. No significant differences were observed for serum C1q between preeclamptic and control pregnancy in any of the three cohorts. Serum levels of FH were lower in preeclamptic pregnancies compared to control pregnancies in two of the cohorts, this effect was driven by the early onset PE cases. Neither anti-C1q autoantibodies nor anti-FH autoantibodies levels differed between women with PE and normal pregnancies. In conclusion, levels of anti-C1q and anti-FH autoantibodies are not increased in PE. C1q and FH are increased in pregnancy, but importantly, a decrease in FH concentration is associated with PE.

Protocol: A randomized controlled trial to assess effectiveness of a 12-month lifestyle intervention to reduce cardiovascular disease risk in families ten years after pre-eclampsia (FINNCARE)

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This is appropriately powered 12-month lifestyle intervention for PE families.

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Detailed phenotyping now and during index pregnancy may identify subgroups at CVD risk.

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Genome-wide genotyping is performed for all study participants.

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Process evaluation examines feasibility and follows Medical Research Council guidance.

Pre-eclampsia (PE) is a multisystem progressive disorder affecting 3–5% of pregnancies. PE independently increases the risk for premature cardiovascular disease (CVD) in mothers and their children long-term. The effectiveness of a family-centered lifestyle intervention to lower CVD risk in PE families has not previously been evaluated. In the current FINNCARE study, we prospectively compare CVD risk and CVD progression in PE families (mother, father and child) in a cross-sectional study setting 8–12 years from delivery with non-PE control families of comparable age. Furthermore, we evaluate the effectiveness and feasibility of an interactive web-based behavioral 12-month lifestyle intervention to reduce blood pressure and the CVD risk profile overall in a randomized controlled trial. In total, 300 PE families will be randomized 1:1 to a PE-intervention or a PE-control group, and the 100 non-PE control families similarly followed-up at 12 months. Primary outcome is 24-hour mean systolic BP change from baseline in mother and child. Study aims to provide information on CVD progression and CVD risk management in the family following PE.

Characteristics of preeclampsia in donor cell gestations

Pregnancies conceived through donor oocytes or sperm show increased risk for preeclampsia. We studied this issue in a preeclampsia case-control cohort (n = 2778), and found overrepresentation of donor cell gestations among women with preeclampsia (14/1627, 0.86%; OR 1.81; 95% CI: 1.07-3.08; P = 0.025) compared to the population data. Moreover, we observed excess of male births from donor cell pregnancies (male-to-female ratio 2.5 vs. 0.97; OR 2.57; 95% CI 1.02-6.36; P = 0.043). Maternal age (36.7 vs. 30.2; P < 0.0001) and preterm deliveries (64% vs. 38%; P = 0.046) distinguished donor cell gestations from other pregnancies with preeclampsia. These results support foreign fetal antigens as modulators of preeclampsia.

Dysfunction of complement receptors CR3 (CD11b/18) and CR4 (CD11c/18) in pre-eclampsia: a genetic and functional study

OBJECTIVE

To study genetic variants and their function within genes coding for complement receptors in pre-eclampsia.

DESIGN

A case-control study.

SETTING

Pre-eclampsia is a common vascular disease of pregnancy. The clearance of placenta-derived material is one of the functions of the complement system in pregnancy.

POPULATION

We genotyped 500 women with pre-eclamptic pregnancies and 190 pregnant women without pre-eclampsia, as controls, from the FINNPEC cohort, and 122 women with pre-eclamptic pregnancies and 1905 controls from the national FINRISK cohort.

METHODS

The functional consequences of genotypes discovered by targeted exomic sequencing were explored by analysing the binding of the main ligand iC3b to mutated CR3 or CR4, which were transiently expressed on the surface of COS-1 cells.

MAIN OUTCOME MEASURES

Allele frequencies were compared between pre-eclamptic pregnancies and controls in genetic studies. The functional consequences of selected variants were measured by binding assays.

RESULTS

The most significantly pre-eclampsia-linked CR3 variant M441K (P = 4.27E-4, OR = 1.401, 95% CI = 1.167-1.682) displayed a trend of increased adhesion to iC3b (P = 0.051). The CR4 variant A251T was found to enhance the adhesion of CR4 to iC3b, whereas W48R resulted in a decrease of the binding of CR4 to iC3b.

CONCLUSIONS

Results suggest that changes in complement-facilitated phagocytosis are associated with pre-eclampsia. Further studies are needed to ascertain whether aberrant CR3 and CR4 activity leads to altered pro- and anti-inflammatory cytokine responses in individuals carrying the associated variants, and the role of these receptors in pre-eclampsia pathogenesis.

TWEETABLE ABSTRACT

Genetic variants of complement receptors CR3 and CR4 have functional consequences that are associated with pre-eclampsia.

A non-targeted LC-MS metabolic profiling of pregnancy: longitudinal evidence from healthy and pre-eclamptic pregnancies

INTRODUCTION

Maternal metabolism changes substantially during pregnancy. However, few studies have used metabolomics technologies to characterize changes across gestation.

OBJECTIVES AND METHODS

We applied liquid chromatography-mass spectrometry (LC-MS) based non-targeted metabolomics to determine whether the metabolic profile of serum differs throughout the pregnancy between pre-eclamptic and healthy women in the FINNPEC (Finnish Genetics of Preeclampsia Consortium) Study. Serum samples were available from early and late pregnancy.

RESULTS

Progression of pregnancy had large-scale effects to the serum metabolite profile. Altogether 50 identified metabolites increased and 49 metabolites decreased when samples of early pregnancy were compared to samples of late pregnancy. The metabolic signatures of pregnancy were largely shared in pre-eclamptic and healthy women, only urea, monoacylglyceride 18:1 and glycerophosphocholine were identified to be increased in the pre-eclamptic women when compared to healthy controls.

CONCLUSIONS

Our study highlights the need of large-scale longitudinal metabolomic studies in non-complicated pregnancies before more detailed understanding of metabolism in adverse outcomes could be provided. Our findings are one of the first steps for a broader metabolic understanding of the physiological changes caused by pregnancy per se.

Genetic predisposition to hypertension is associated with preeclampsia in European and Central Asian women

Preeclampsia is a serious complication of pregnancy, affecting both maternal and fetal health. In genome-wide association meta-analysis of European and Central Asian mothers, we identify sequence variants that associate with preeclampsia in the maternal genome at ZNF831/20q13 and FTO/16q12. These are previously established variants for blood pressure (BP) and the FTO variant has also been associated with body mass index (BMI). Further analysis of BP variants establishes that variants at MECOM/3q26, FGF5/4q21 and SH2B3/12q24 also associate with preeclampsia through the maternal genome. We further show that a polygenic risk score for hypertension associates with preeclampsia. However, comparison with gestational hypertension indicates that additional factors modify the risk of preeclampsia.

The non-traditional and familial risk factors for preeclampsia in the FINNPEC cohort

OBJECTIVES

Considering the burden of preeclampsia (PE), it is important to understand better the underlying risk factors involved in its etiology. We studied the association of background factors with PE with an emphasis on socioeconomic factors, reproductive factors and health history enclosing the parents of pregnant women.

STUDY DESIGN

The Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort participants filled in a questionnaire on background information. The questionnaire data was available from 708 women with PE and 724 control women. Two different control groups, healthy controls with uncomplicated pregnancies (n = 498) and all controls (n = 724, including controls with uncomplicated pregnancies and pregnancy complications other than PE), were established.

RESULTS

PE women had similar socioeconomic status and more often non-communicable diseases including type 1 diabetes, chronic hypertension and hyperlipidemia than the two control groups (p < 0.05 for all). Depression and subfertility were more common among PE women and they had earlier menarche (p < 0.05 for all). Hypertension was more common in both parents of PE women, stroke in fathers and diabetes in mothers (p < 0.05 for all). Mental disorders including depression were more common in mothers of PE women compared to controls (PE women 7.2%, healthy controls 3.7% (p = 0.013) and all controls 3.9% (p = 0.007)).

CONCLUSIONS

In the FINNPEC cohort, PE women had similar socioeconomic status, more non-communicable diseases and depression, earlier menarche, more subfertility and more parental non-communicable diseases compared to controls. As a novel finding we found more mental disorders including depression in mothers of PE women.

Fetal HLA-G mediated immune tolerance and interferon response in preeclampsia

BACKGROUND

Fetal immune tolerance is crucial for pregnancy success. We studied the link between preeclampsia, a severe pregnancy disorder with uncertain pathogenesis, and fetal human leukocyte antigen G (HLA-G) and other genes regulating maternal immune responses.

METHODS

We assessed sex ratios and regulatory HLA-G haplotypes in population cohorts and series of preeclampsia and stillbirth. We studied placental mRNA expression of 136 genes by sequencing and HLA-G and interferon alpha (IFNα) protein expression by immunohistochemistry.

FINDINGS

We found underrepresentation of males in preeclamptic births, especially those delivered preterm or small for gestational age. Balancing selection at HLA-G associated with the sex ratio, stillbirth, and preeclampsia. We observed downregulation of HLA-G, its receptors, and many other tolerogenic genes, and marked upregulation of IFNA1 in preeclamptic placentas.

INTERPRETATION

These findings indicate that an evolutionary trade-off between immune tolerance and protection against infections at the maternal-fetal interface promotes genetic diversity in fetal HLA-G, thereby affecting survival, preeclampsia, and sex ratio. We highlight IFNA1 as a potential mediator of preeclampsia and a target for therapeutic trials.

FUNDING

Finnish Medical Foundation, Päivikki and Sakari Sohlberg Foundation, Karolinska Institutet Research Foundation, Scandinavia-Japan Sasakawa Foundation, Japan Eye Bank Association, Astellas Foundation for Research on Metabolic Disorders, Japan Society for the Promotion of Science, Knut and Alice Wallenberg Foundation, Swedish Research Council, Medical Society Liv och Hälsa, Sigrid Jusélius Foundation, Helsinki University Hospital and University of Helsinki, Jane and Aatos Erkko Foundation, Academy of Finland, Finska Läkaresällskapet, Novo Nordisk Foundation, Finnish Foundation for Pediatric Research, and Emil Aaltonen Foundation.

MSC-Secreted Exosomal H19 Promotes Trophoblast Cell Invasion and Migration by Downregulating let-7b and Upregulating FOXO1

Exosomes perform important functions for intercellular communication through extracellular signaling pathways, leading to the regulation of important biological processes, including cell proliferation, but also systemic dysfunctions such as preeclampsia (PE). However, the inhibitory effects of mesenchymal stem cell (MSCs)-derived exosomes in PE remain largely unknown. Thus, we assessed the possibility that exosomes could transport long non-coding RNA H19 and the correlation between H19 and the apoptosis of trophoblast cells. The expression of microRNA let-7b and forkhead box protein O1 (FOXO1) was characterized in placental tissues of PE patients. Gain- and loss-of-function experiments were performed to examine the roles of FOXO1 and let-7b in trophoblast cells. Interactions between let-7b and H19 as well as between let-7b and FOXO1 were confirmed by a dual-luciferase reporter assay, RNA pull-down, and RNA immunoprecipitation. HTR-8/SVneo cells were co-cultured with exosomes derived from MSCs overexpressing H19, followed by invasion, migration, and apoptosis assessments of trophoblast cells. We found that let-7b was highly expressed and FOXO1 was poorly expressed in placental tissues of PE patients. Furthermore, H19 acts as a competitive endogenous RNA against let-7b, and let-7b directly targeted FOXO1. Moreover, H19 could be transferred to trophoblast cells via MSC-secreted exosomes. MSC-derived exosomes overexpressing H19 decreased let-7b, increased FOXO1, and activated the protein kinase B (AKT) signaling pathway, thus increasing invasion and migration and inhibiting apoptosis of trophoblast cells. These results suggest that MSC-derived exosomes overexpressing H19 may be a novel direction for therapeutic strategies against PE.

The Immunogenetic Conundrum of Preeclampsia

Pregnancy is an immunological challenge to the mother. The fetal tissues including the placenta must be protected from activation of the maternal immune system. On the other hand, the placental tissue sheds into the maternal circulation and must be adequately identified and phagocytized by the maternal immune system. During a healthy pregnancy, numerous immunosuppressive processes take place that allow the allograft fetus to thrive under exposure to humoral and cellular components of the maternal immune system. Breakdown of immune tolerance may result in sterile inflammation and cause adverse pregnancy outcomes such as preeclampsia, a vascular disease of the pregnancy with unpredictable course and symptoms from several organs. Immunological incompatibility between mother and fetus is strongly indicated in preeclampsia. Recently, genetic factors linking immunological pathways to predisposition to preeclampsia have been identified. In this mini-review genetic variation in immunological factors are discussed in the context of preeclampsia. Specifically, we explore immunogenetic and immunomodulary mechanisms contributing to loss of tolerance, inflammation, and autoimmunity in preeclampsia.

A Non-Targeted LC-MS Profiling Reveals Elevated Levels of Carnitine Precursors and Trimethylated Compounds in the Cord Plasma of Pre-Eclamptic Infants

Preeclampsia (PE) is a complex pregnancy disorder. It is not extensively known how the metabolic alterations of PE women contribute to the metabolism of newborn. We applied liquid chromatography-mass spectrometry (LC-MS) based non-targeted metabolomics to determine whether the metabolic profile of plasma from umbilical cord differs between infants born to PE and non-PE pregnancies in the FINNPEC study. Cord plasma was available from 42 newborns born from PE and 53 from non-PE pregnancies. 133 molecular features differed between PE and non-PE newborns after correction for multiple testing. Decreased levels of 4-pyridoxic acid were observed in the cord plasma samples of PE newborns when compared to non-PE newborns. Compounds representing following areas of metabolism were increased in the cord plasma of PE newborns: urea and creatine metabolism; carnitine biosynthesis and acylcarnitines; putrescine metabolites; tryptophan metabolism and phosphatidylcholines. To our knowledge, this study is the first one to apply LC-MS based metabolomics in cord plasma of PE newborns. We demonstrate that this strategy provides a global picture of the widespread metabolic alterations associated with PE and particularly the elevated levels of carnitine precursors and trimethylated compounds appear to be associated with PE at birth.

Preeclampsia is associated with hypermethylation of IGF-1 promoter mediated by DNMT1

Previous studies have demonstrated a dynamic epigenetic regulation of genes expression in placenta trophoblasts and a dynamic imbalance of DNA methylation and hydroxymethylation. Reduced IGF-1 has been observed in preeclampsia. This study was to investigate the interactive roles between IGF-1 and the global DNA methylation/hydroxymethylation, and the status of DNA methylation/hydroxymethylation and associated enzymes such as DNMTs and TETs in peeeclamptic placentas and hypoxic trophoblasts. It was found that IGF-1 was decreased in preeclamptic placentas and hypoxic trophoblasts when compared to the control group using immunohistochemisty, western blot, qRT-PCR and ELISA. Pyrophosphate sequencing showed IGF-1 promoter was significantly hypermethylated in preeclamptic placentas, which was responsible for reduced IGF-1 expression. Preeclamptic placentas and hypoxic trophoblasts were hypermethylated and hypohydroxymethylated accompanied by remarkably higher 5mC, DNMT1 and DNMT3b, and lower DNMT3a, 5hmC, TET1, TET2 and TET3 detected by immunohistochemisty, western blot, qRT-PCR and ELISA. Pearson's correlation confirmed a statistically significant negative correlation between IGF-1 and DNMT1. Furthermore, both treatment with 5-Aza-dc and DNMT1-siRNA significantly increased the expression of IGF-1 in HTR8 cells, indicating the potential mechanism of DNMT1-mediated DNA methylation in IGF-1 regulation. However, IGF-1 didn't change DNA methylation or hydroxymethylation. These findings suggest that preeclampsia is associated with hypermethylation of IGF-1 promoter mediated by DNMT1 and provide new insights into the diagnosis and treatment of preeclampsia.

Fetal Microsatellite in the Heme Oxygenase 1 Promoter Is Associated With Severe and Early-Onset Preeclampsia

Preeclampsia is a vascular pregnancy disorder that often involves impaired placental development. HO-1 (heme oxygenase 1, encoded by HMOX1 ) is a stress response enzyme crucial for endothelial and placental function. Long version of the guanine–thymine (GT n ) microsatellite in the HMOX1 promoter decreases HO-1 expression, and the long maternal repeat is associated with late-onset preeclampsia. Our aim was to study whether the length of fetal repeat is associated with mother’s preeclampsia, whether the length of fetal and maternal repeats affect HO-1 levels in placenta and maternal serum, and whether HO-1 levels are altered in preeclampsia. We genotyped the repeat in the cord blood of 609 preeclamptic and 745 nonpreeclamptic neonates. HO-1 levels were measured in 36 placental samples, and in the first (222 cases/243 controls) and third (176 cases/53 controls) pregnancy trimester serum samples using enzyme-linked immunosorbent assay. The long fetal GT n repeat was associated with preeclampsia and its severe and early-onset subtypes. Interaction analysis suggested the maternal and fetal effects to be independent. Placental or serum HO-1 levels were not altered in preeclamptics, possibly reflecting heterogeneity of preeclampsia. Carriers of the long fetal and maternal repeats had lower placental and serum HO-1 levels, respectively, providing functional evidence for the association. We conclude that the long fetal GT n repeat may increase mother’s risk for especially severe and early-onset preeclampsia. The fetal and maternal risk alleles likely predispose to different disease subtypes.

Angiogenic profile and smoking in the Finnish Genetics of Pre-Eclampsia Consortium (FINNPEC) cohort

OBJECTIVES

The biological mechanism by which smoking reduces the risk of pre-eclampsia (PE) is unresolved. We studied serum levels of soluble fms-like tyrosine kinase 1 (sFlt-1), placental growth factor (PlGF) and their ratio, in addition to soluble endoglin (sEng) in early and late pregnancy to ascertain whether these factors are altered in women who smoke.

SUBJECTS AND METHODS

First trimester serum samples were available from 217 women who later developed PE and 238 women who did not develop PE. Second/third trimester serum samples were available from 174 PE and 54 non-PE women.

RESULTS

PE women who smoked during pregnancy had elevated first trimester concentrations of serum PlGF [geometric mean (95% CI): 39.8 (32.6-48.5) pg/ml, p = .001] and reduced sEng concentration [5.0 (4.6-5.6) ng/ml, p = .047] compared to PE non-smokers [30.0 (28.1-32.1) pg/ml and 6.1 (5.9-6.4) ng/ml, respectively]. Non-smoking women in the PE group had the highest sFlt-1/PlGF ratio in early and late pregnancy.

CONCLUSIONS

The protective effect of smoking in reducing the risk of PE may be due to the early pregnancy change towards pro-angiogenic marker profile. Also, in late pregnancy, smoking exerted effect in sFlt-1/PlGF ratio in PE pregnancies, and may complicate its use as a prognostic and diagnostic marker. Key messages Smoking appears to have angiogenic effects in early pregnancy with reduced sEng concentrations and elevated PlGF concentrations in both normal and PE pregnancies. Throughout pregnancy, smoking exerted effect in PlGF concentration and sFlt-1/PlGF ratio in PE pregnancies, and thus may complicate its use as a prognostic and diagnostic marker.

Protective Low-Frequency Variants for Preeclampsia in the Fms Related Tyrosine Kinase 1 Gene in the Finnish Population

Preeclampsia is a common pregnancy-specific vascular disorder characterized by new-onset hypertension and proteinuria during the second half of pregnancy. Predisposition to preeclampsia is in part heritable. It is associated with an increased risk of cardiovascular disease later in life. We have sequenced 124 candidate genes implicated in preeclampsia to pinpoint genetic variants contributing to predisposition to or protection from preeclampsia. First, targeted exomic sequencing was performed in 500 preeclamptic women and 190 controls from the FINNPEC cohort (Finnish Genetics of Preeclampsia Consortium). Then 122 women with a history of preeclampsia and 1905 parous women with no such history from the National FINRISK Study (a large Finnish population survey on risk factors of chronic, noncommunicable diseases) were included in the analyses. We tested 146 rare and low-frequency variants and found an excess (observed 13 versus expected 7.3) nominally associated with preeclampsia (P<0.05). The most significantly associated sequence variants were protective variants rs35832528 (E982A; P=2.49E-4; odds ratio=0.387) and rs141440705 (R54S; P=0.003; odds ratio=0.442) in Fms related tyrosine kinase 1. These variants are enriched in the Finnish population with minor allele frequencies 0.026 and 0.017, respectively. They may also be associated with a lower risk of heart failure in 11 257 FINRISK women. This study provides the first evidence of maternal protective genetic variants in preeclampsia.

Variants in the fetal genome near FLT1 are associated with risk of preeclampsia

Preeclampsia, which affects approximately 5% of pregnancies, is a leading cause of maternal and perinatal death. The causes of preeclampsia remain unclear, but there is evidence for inherited susceptibility. Genome-wide association studies (GWAS) have not identified maternal sequence variants of genome-wide significance that replicate in independent data sets. We report the first GWAS of offspring from preeclamptic pregnancies and discovery of the first genome-wide significant susceptibility locus (rs4769613; P = 5.4 × 10^-11) in 4,380 cases and 310,238 controls. This locus is near the FLT1 gene encoding Fms-like tyrosine kinase 1, providing biological support, as a placental isoform of this protein (sFlt-1) is implicated in the pathology of preeclampsia. The association was strongest in offspring from pregnancies in which preeclampsia developed during late gestation and offspring birth weights exceeded the tenth centile. An additional nearby variant, rs12050029, associated with preeclampsia independently of rs4769613. The newly discovered locus may enhance understanding of the pathophysiology of preeclampsia and its subtypes.

Analysis of Complement C3 Gene Reveals Susceptibility to Severe Preeclampsia

Preeclampsia (PE) is a common vascular disease of pregnancy with genetic predisposition. Dysregulation of the complement system has been implicated, but molecular mechanisms are incompletely understood. In this study, we determined the potential linkage of severe PE to the most central complement gene, C3. Three cohorts of Finnish patients and controls were recruited for a genetic case-control study. Participants were genotyped using Sequenom genotyping and Sanger sequencing. Initially, we studied 259 Finnish patients with severe PE and 426 controls from the Southern Finland PE and the Finnish population-based PE cohorts. We used a custom-made single nucleotide polymorphism (SNP) genotyping assay consisting of 98 SNPs in 18 genes that encode components of the complement system. Following the primary screening, C3 was selected as the candidate gene and consequently Sanger sequenced. Fourteen SNPs from C3 were also genotyped by a Sequenom panel in 960 patients with severe PE and 705 controls, including already sequenced individuals. Three of the 43 SNPs observed within C3 were associated with severe PE: rs2287845 (p = 0.038, OR = 1.158), rs366510 (p = 0.039, OR = 1.158), and rs2287848 (p = 0.041, OR = 1.155). We also discovered 16 SNP haplotypes with extreme linkage disequilibrium in the middle of the gene with a protective (p = 0.044, OR = 0.628) or a predisposing (p = 0.011, OR = 2.110) effect to severe PE depending on the allele combination. Genetic variants associated with PE are located in key domains of C3 and could thereby influence the function of C3. This is, as far as we are aware, the first candidate gene in the complement system with an association to a clinically relevant PE subphenotype, severe PE. The result highlights a potential role for the complement system in the pathogenesis of PE and may help in defining prognostic and therapeutic subgroups of preeclamptic women.