Higher maternal plasma glucose (PG) concentrations, even below gestational diabetes mellitus (GDM) thresholds, are associated with adverse offspring outcomes, with DNA methylation proposed as a ...mediating mechanism. Here, we examined the relationships between maternal dysglycaemia at 24 to 28 weeks' gestation and DNA methylation in neonates and whether a dietary and physical activity intervention in pregnant women with obesity modified the methylation signatures associated with maternal dysglycaemia.
We investigated 557 women, recruited between 2009 and 2014 from the UK Pregnancies Better Eating and Activity Trial (UPBEAT), a randomised controlled trial (RCT), of a lifestyle intervention (low glycaemic index (GI) diet plus physical activity) in pregnant women with obesity (294 contol, 263 intervention). Between 27 and 28 weeks of pregnancy, participants had an oral glucose (75 g) tolerance test (OGTT), and GDM diagnosis was based on diagnostic criteria recommended by the International Association of Diabetes and Pregnancy Study Groups (IADPSG), with 159 women having a diagnosis of GDM. Cord blood DNA samples from the infants were interrogated for genome-wide DNA methylation levels using the Infinium Human MethylationEPIC BeadChip array. Robust regression was carried out, adjusting for maternal age, smoking, parity, ethnicity, neonate sex, and predicted cell-type composition. Maternal GDM, fasting glucose, 1-h, and 2-h glucose concentrations following an OGTT were associated with 242, 1, 592, and 17 differentially methylated cytosine-phosphate-guanine (dmCpG) sites (false discovery rate (FDR) ≤ 0.05), respectively, in the infant's cord blood DNA. The most significantly GDM-associated CpG was cg03566881 located within the leucine-rich repeat-containing G-protein coupled receptor 6 (LGR6) (FDR = 0.0002). Moreover, we show that the GDM and 1-h glucose-associated methylation signatures in the cord blood of the infant appeared to be attenuated by the dietary and physical activity intervention during pregnancy; in the intervention arm, there were no GDM and two 1-h glucose-associated dmCpGs, whereas in the standard care arm, there were 41 GDM and 160 1-h glucose-associated dmCpGs. A total of 87% of the GDM and 77% of the 1-h glucose-associated dmCpGs had smaller effect sizes in the intervention compared to the standard care arm; the adjusted r2 for the association of LGR6 cg03566881 with GDM was 0.317 (95% confidence interval (CI) 0.012, 0.022) in the standard care and 0.240 (95% CI 0.001, 0.015) in the intervention arm. Limitations included measurement of DNA methylation in cord blood, where the functional significance of such changes are unclear, and because of the strong collinearity between treatment modality and severity of hyperglycaemia, we cannot exclude that treatment-related differences are potential confounders.
Maternal dysglycaemia was associated with significant changes in the epigenome of the infants. Moreover, we found that the epigenetic impact of a dysglycaemic prenatal maternal environment appeared to be modified by a lifestyle intervention in pregnancy. Further research will be needed to investigate possible medical implications of the findings.
ISRCTN89971375.
DNA methylation (DNAm) in mammals is mostly examined within the context of CpG dinucleotides. Non-CpG DNAm is also widespread across the human genome, but the functional relevance, tissue-specific ...disposition, and inter-individual variability has not been widely studied. Our aim was to examine non-CpG DNAm in the wider methylome across multiple tissues from the same individuals to better understand non-CpG DNAm distribution within different tissues and individuals and in relation to known genomic regulatory features.
DNA methylation in umbilical cord and cord blood at birth, and peripheral venous blood at age 12-13 y from 20 individuals from the Southampton Women's Survey cohort was assessed by Agilent SureSelect methyl-seq. Hierarchical cluster analysis (HCA) was performed on CpG and non-CpG sites and stratified by specific cytosine environment. Analysis of tissue and inter-individual variation was then conducted in a second dataset of 12 samples: eight muscle tissues, and four aliquots of cord blood pooled from two individuals.
HCA using methylated non-CpG sites showed different clustering patterns specific to the three base-pair triplicate (CNN) sequence. Analysis of CAC sites with non-zero methylation showed that samples clustered first by tissue type, then by individual (as observed for CpG methylation), while analysis using non-zero methylation at CAT sites showed samples grouped predominantly by individual. These clustering patterns were validated in an independent dataset using cord blood and muscle tissue.
This research suggests that CAC methylation can have tissue-specific patterns, and that individual effects, either genetic or unmeasured environmental factors, can influence CAT methylation.
•Observational studies suggest maternal nutrition can impact perinatal mental health.•This trial randomized women to a control or intervention nutritional supplement.•The nutritional supplements were ...taken before conception and during pregnancy.•Nutritional supplementation did not influence the mother's perinatal mood/anxiety.•Myo-inositol, probiotics and micronutrients improved mental health functioning.
Observational studies have reported associations between nutrition during pregnancy and mental wellbeing. As secondary outcomes, the NiPPeR double-blind randomized trial in women planning conception investigated whether a myo-inositol, probiotics and enriched micronutrients formulation (intervention) taken preconception and throughout pregnancy could improve mental wellbeing during pregnancy and post-delivery, compared with a standard micronutrient supplement (control). Mood and anxiety symptoms were ascertained (Edinburgh Postnatal Depression Scale (EPDS), State-Trait Anxiety Inventory (STAI-state)) at preconception (baseline), 7, 28 and 34 weeks gestation, 3-weeks and 6-months post-delivery. EPDS>=13 was categorised as low mood; STAI-state>=45 as high anxiety. Change in mental health functioning was assessed as difference between preconception baseline and 6-month post-delivery 12-item Short-Form Health Survey (SF-12v2) mental component scores. Adjusting for site, ethnicity and baseline scores, there were no robust differences in EPDS and STAI-state scores between intervention and control groups across pregnancy (n = 630) and post-delivery (n = 532). Compared to controls, intervention group women averaged a 1.21 (95 %CI 0.04,2.39) higher change in SF-12v2 mental component score from preconception to 6-months post-delivery. Taking a myo-inositol, micronutrient and probiotic supplement during preconception/pregnancy had no effect on mood and anxiety, but there was evidence of a modest improvement in mental health functioning from preconception to 6-months post-delivery.
Asthma is a chronic inflammatory airway disease that affects more than 300 million individuals worldwide. Asthma is caused by interaction of genetic and environmental factors. Bronchial ...hyperresponsiveness (BHR) is a hallmark of asthma and results from increased sensitivity of the airways to physical or chemical stimulants. BHR and asthma are linked to chromosome 5q31-q33.
To identify a gene for BHR on chromosome 5q31-q33.
In 200 Dutch families with asthma, linkage analysis and fine mapping were performed, and the Protocadherin 1 gene (PCDH1) was identified. PCDH1 was resequenced in 96 subjects from ethnically diverse populations to identify novel sequence variants. Subsequent replication studies were undertaken in seven populations from The Netherlands, the United Kingdom, and the United States, including two general population samples, two family samples, and three case-control samples. PCDH1 mRNA and protein expression was investigated using polymerase chain reaction, Western blotting, and immunohistochemistry.
In seven out of eight populations (n = 6,168) from The Netherlands, United Kingdom, and United States, PCHD1 gene variants were significantly associated with BHR (P values, 0.005-0.05) This association was present in both families with asthma and general populations. PCDH1 mRNA and protein were expressed in airway epithelial cells and in macrophages.
PCDH1 is a novel gene for BHR in adults and children. The identification of PCDH1 as a BHR susceptibility gene may suggest that a structural defect in the integrity of the airway epithelium, the first line of defense against inhaled substances, contributes to the development of BHR.
Maternal vitamin status preconception and during pregnancy has important consequences for pregnancy outcome and offspring development. Changes in vitamin status from preconception through early and ...late pregnancy and postpartum have been inferred from cross-sectional data, but longitudinal data on vitamin status from preconception throughout pregnancy and postdelivery are sparse. As such, the influence of vitamin supplementation on vitamin status during pregnancy remains uncertain. This study presents one prespecified outcome from the randomized controlled NiPPeR trial, aiming to identify longitudinal patterns of maternal vitamin status from preconception, through early and late pregnancy, to 6 months postdelivery, and determine the influence of vitamin supplementation.
In the NiPPeR trial, 1,729 women (from the United Kingdom, Singapore, and New Zealand) aged 18 to 38 years and planning conception were randomized to receive a standard vitamin supplement (control; n = 859) or an enhanced vitamin supplement (intervention; n = 870) starting in preconception and continued throughout pregnancy, with blinding of participants and research staff. Supplement components common to both treatment groups included folic acid, β-carotene, iron, calcium, and iodine; components additionally included in the intervention group were riboflavin, vitamins B6, B12, and D (in amounts available in over-the-counter supplements), myo-inositol, probiotics, and zinc. The primary outcome of the study was glucose tolerance at 28 weeks' gestation, measured by oral glucose tolerance test. The secondary outcome reported in this study was the reduction in maternal micronutrient insufficiency in riboflavin, vitamin B6, vitamin B12, and vitamin D, before and during pregnancy. We measured maternal plasma concentrations of B-vitamins, vitamin D, and markers of insufficiency/deficiency (homocysteine, hydroxykynurenine-ratio, methylmalonic acid) at recruitment, 1 month after commencing intervention preconception, in early pregnancy (7 to 11 weeks' gestation) and late pregnancy (around 28 weeks' gestation), and postdelivery (6 months after supplement discontinuation). We derived standard deviation scores (SDS) to characterize longitudinal changes among participants in the control group and measured differences between the 2 groups. At recruitment, the proportion of patients with marginal or low plasma status was 29.2% for folate (<13.6 nmol/L), 7.5% and 82.0% for riboflavin (<5 nmol/L and ≤26.5 nmol/L, respectively), 9.1% for vitamin B12 (<221 pmol/L), and 48.7% for vitamin D (<50 nmol/L); these proportions were balanced between the groups. Over 90% of all participants had low or marginal status for one or more of these vitamins at recruitment. Among participants in the control group, plasma concentrations of riboflavin declined through early and late pregnancy, whereas concentrations of 25-hydroxyvitamin D were unchanged in early pregnancy, and concentrations of vitamin B6 and B12 declined throughout pregnancy, becoming >1 SDS lower than baseline by 28 weeks gestation. In the control group, 54.2% of participants developed low late-pregnancy vitamin B6 concentrations (pyridoxal 5-phosphate <20 nmol/L). After 1 month of supplementation, plasma concentrations of supplement components were substantially higher among participants in the intervention group than those in the control group: riboflavin by 0.77 SDS (95% CI 0.68 to 0.87, p < 0.0001), vitamin B6 by 1.07 SDS (0.99 to 1.14, p < 0.0001), vitamin B12 by 0.55 SDS (0.46 to 0.64, p < 0.0001), and vitamin D by 0.51 SDS (0.43 to 0.60, p < 0.0001), with higher levels in the intervention group maintained during pregnancy. Markers of vitamin insufficiency/deficiency were reduced in the intervention group, and the proportion of participants with vitamin D insufficiency (<50 nmol/L) during late pregnancy was lower in the intervention group (35.1% versus 8.5%; p < 0.0001). Plasma vitamin B12 remained higher in the intervention group than in the control group 6 months postdelivery (by 0.30 SDS (0.14, 0.46), p = 0.0003). The main limitation is that generalizability to the global population is limited by the high-resource settings and the lack of African and Amerindian women in particular.
Over 90% of the trial participants had marginal or low concentrations of one or more of folate, riboflavin, vitamin B12, or vitamin D during preconception, and many developed markers of vitamin B6 deficiency in late pregnancy. Preconception/pregnancy supplementation in amounts available in over-the-counter supplements substantially reduces the prevalence of vitamin deficiency and depletion markers before and during pregnancy, with higher maternal plasma vitamin B12 maintained during the recommended lactational period.
ClinicalTrials.gov NCT02509988; U1111-1171-8056.
We previously reported that a combined myo-inositol, probiotics, and enriched micronutrient supplement (intervention) taken preconception and in pregnancy reduced postpartum blood loss (PBL) and ...major postpartum hemorrhage compared with a standard micronutrient supplement (control), as secondary outcomes of the NiPPeR trial. This study aimed to identify the intervention components that may contribute to this effect. Associations of plasma concentrations of myo-inositol and vitamins B2, B6, B12, and D at preconception (before and after supplementation), early (~7-weeks), and late pregnancy (~28-weeks) with PBL were assessed by multiple linear regression, adjusting for site, ethnicity, preconception BMI, parity, and previous cesarean section. Amongst 583 women, a higher concentration of myo-inositol in early pregnancy was associated with a PBL reduction βadj −1.26 (95%CI −2.23, −0.29) mL per µmol/L myo-inositol increase, p = 0.011. Applying this co-efficient to the increase in mean 7-week-myo-inositol concentration of 23.4 µmol/L with the intervention equated to a PBL reduction of 29.5 mL (~8.4% of mean PBL of 350 mL among controls), accounting for 84.3% of the previously reported intervention effect of 35 mL. None of the examined vitamins were associated with PBL. Therefore, myo-inositol may be a key intervention component mediating the PBL reduction. Further work is required to determine the mechanisms involved.
Nutritional intervention preconception and throughout pregnancy has been proposed as an approach to promoting healthy postnatal weight gain in the offspring but few randomised trials have examined ...this.
Measurements of weight and length were obtained at multiple time points from birth to 2 years among 576 offspring of women randomised to receive preconception and antenatally either a supplement containing myo-inositol, probiotics, and additional micronutrients (intervention) or a standard micronutrient supplement (control). We examined the influence on age- and sex-standardised BMI at 2 years (WHO standards, adjusting for study site, sex, maternal parity, smoking and pre-pregnancy BMI, and gestational age), together with the change in weight, length, BMI from birth, and weight gain trajectories using latent class growth analysis.
At 2 years, there was a trend towards lower mean BMI among intervention offspring (adjusted mean difference aMD - 0.14 SD 95% CI 0.30, 0.02, p = 0.09), and fewer had a BMI > 95th percentile (i.e. > 1.65 SD, 9.2% vs 18.0%, adjusted risk ratio aRR 0.51 95% CI 0.31, 0.82, p = 0.006). Longitudinal data revealed that intervention offspring had a 24% reduced risk of experiencing rapid weight gain > 0.67 SD in the first year of life (21.9% vs 31.1%, aRR 0.76 95% CI 0.58, 1.00, p = 0.047). The risk was likewise decreased for sustained weight gain > 1.34 SD in the first 2 years of life (7.7% vs 17.1%, aRR 0.55 95% CI 0.34, 0.88, p = 0.014). From five weight gain trajectories identified, there were more intervention offspring in the "normal" weight gain trajectory characterised by stable weight SDS around 0 SD from birth to 2 years (38.8% vs 30.1%, RR 1.29 95% CI 1.03, 1.62, p = 0.029).
Supplementation with myo-inositol, probiotics, and additional micronutrients preconception and in pregnancy reduced the incidence of rapid weight gain and obesity at 2 years among offspring. Previous reports suggest these effects will likely translate to health benefits, but longer-term follow-up is needed to evaluate this.
ClinicalTrials.gov, NCT02509988 (Universal Trial Number U1111-1171-8056). Registered on 16 July 2015.
Association studies of epigenome-wide DNA methylation and disease can inform biological mechanisms. DNA methylation is often measured in peripheral blood, with heterogeneous cell types with different ...methylation profiles. Influences such as adiposity-associated inflammation can change cell-type proportions, altering measured blood methylation levels. To determine whether associations between loci-specific methylation and outcomes result from cellular heterogeneity, many studies adjust for estimated blood cell proportions, but high correlations between methylation and cell-type proportions could violate the statistical assumption of no multicollinearity. We examined these assumptions in a population-based study.
promoter CpG methylation was measured in peripheral blood from 812 adolescents aged 17 years (Western Australian Pregnancy Cohort Study). Log
adolescent BMI was used as the outcome in a regression analysis with DNA methylation as predictor, adjusting for age/sex. Further regression analyses additionally adjusted for estimated cell-type proportions using the reference-based Houseman method, and simulations modeled the effects of varying levels of correlation between cell proportions and methylation. Correlations between estimated cell proportions and CpG methylation from Illumina 450K were measured.
Lower DNA methylation was associated with higher BMI when cell-type adjustment was not included; for CpG4, β = -0.004 log
BMI/%methylation (95% CI -0.0065, -0.001;
= 0.003). The direction of association reversed when adjustment for six cell types was made; for CpG4, β = 0.004 log
BMI/%methylation (-0.0002, 0.0089;
= 0.06). Correlations between CpG methylation and cell-type proportions were high, and variance inflation factors (VIFs) were extremely high (25 to 113.7). Granulocyte count was correlated with BMI, and removing granulocytes from the regression model reduced all VIFs to <3.1, with persistence of a positive association between methylation and BMI CpG4 β = 0.004 log
BMI/%methylation (-0.0002, 0.0088;
= 0.06). Simulations supported major effects of multicollinearity on regression results.
Where cell types are highly correlated with other covariates in regression models, the statistical assumption of no multicollinearity may be violated. This can result in reversal of direction of association, particularly when examining associations with phenotypes related to inflammation, as CpG methylation may associate with changes in cell-type proportions. Removing predictors with high correlations from regression models may remove the multicollinearity. However, this might hinder biological interpretability.
Abstract
Context
Single-nucleotide polymorphisms (SNPs) in genes related to vitamin D metabolism have been associated with serum 25-hydroxyvitamin D 25(OH)D concentration, but these relationships ...have not been examined following antenatal cholecalciferol supplementation.
Objective
To determine whether SNPs in DHCR7, CYP2R1, CYP24A1, and GC are associated with the response to gestational cholecalciferol supplementation.
Design
Within-randomization group analysis of the Maternal Vitamin D Osteoporosis Study trial of antenatal cholecalciferol supplementation.
Setting
Hospital antenatal clinics.
Participants
In total, 682 women of white ethnicity (351 placebo, 331 cholecalciferol) were included. SNPs at rs12785878 (DHCR7), rs10741657 (CYP2R1), rs6013897 (CYP24A1), and rs2282679 (GC) were genotyped.
Interventions
1000 IU/d cholecalciferol from 14 weeks of gestation until delivery.
Main Outcome Measure
25(OH)D at randomization and 34 weeks of gestation were measured in a single batch (Liaison; Diasorin, Dartford, UK). Associations between 25(OH)D and the SNPs were assessed by linear regression using an additive model β represents the change in 25(OH)D per additional common allele.
Results
Only rs12785878 (DHCR7) was associated with baseline 25(OH)D β = 3.1 nmol/L; 95% confidence interval (CI), 1.0 to 5.2 nmol/L; P < 0.004. In contrast, rs10741657 (CYP2R1) (β = −5.2 nmol/L; 95% CI, −8.2 to −2.2 nmol/L; P = 0.001) and rs2282679 (GC) (β = 4.2 nmol/L; 95% CI, 0.9 to 7.5 nmol/L; P = 0.01) were associated with achieved 25(OH)D status following supplementation, whereas rs12785878 and rs6013897 (CYP24A1) were not.
Conclusions
Genetic variation in DHCR7, which encodes 7-dehyrocholesterol reductase in the epidermal vitamin D biosynthesis pathway, appears to modify baseline 25(OH)D. In contrast, the response to antenatal cholecalciferol supplementation was associated with SNPs in CYP2R1, which may alter 25-hydroxylase activity, and GC, which may affect vitamin D binding protein synthesis or metabolite affinity.
Associations between SNPs in the vitamin D metabolism pathway and 25(OH)D were assessed before and after antenatal vitamin D supplementation. The associations differed at the two time points.
A previous genome-wide linkage scan of bronchial hyperresponsiveness (BHR) in the French Epidemiological study on the Genetics and Environment of Asthma (EGEA) families, performed in the presence of ...a gene×early-life environmental tobacco smoke (ETS) exposure interaction, showed the strongest interaction in the 17p11 region where linkage was detected only among unexposed siblings. Our goal was to conduct fine-scale mapping of 17p11 to identify single nucleotide polymorphisms (SNPs) interacting with ETS that influence BHR.Analyses were performed in 388 French EGEA asthmatic families, using a two-step strategy: 1) selection of SNPs displaying family-based association test (FBAT) association signals (p≤0.01) with BHR in unexposed siblings, and 2) a FBAT homogeneity test between exposed and unexposed siblings plus a robust log-linear interaction test.A single SNP reached the threshold (p≤3×10(-3)) for significant interaction with ETS using both interaction tests, after accounting for multiple testing. Results were replicated in 253 French-Canadian families, but not in 341 UK families, probably due in part to differences in phenotypic features between datasets.The SNP showing significant interaction with ETS belongs toDNAH9(dynein, axonemal, heavy chain 9), a promising candidate gene involved in respiratory cilia mobility and associated with primary ciliary dyskinesia, a disease associated with abnormalities of pulmonary function.
PDF
