A Pregnancy and Childhood Epigenetics Consortium (PACE) meta-analysis highlights potential relationships between birth order and neonatal blood DNA methylation

Higher birth order is associated with altered risk of many disease states. Changes in placentation and exposures to in utero growth factors with successive pregnancies may impact later life disease risk via persistent DNA methylation alterations. We investigated birth order with Illumina DNA methylation array data in each of 16 birth cohorts (8164 newborns) with European, African, and Latino ancestries from the Pregnancy and Childhood Epigenetics Consortium. Meta-analyzed data demonstrated systematic DNA methylation variation in 341 CpGs (FDR adjusted P < 0.05) and 1107 regions. Forty CpGs were located within known quantitative trait loci for gene expression traits in blood, and trait enrichment analysis suggested a strong association with immune-related, transcriptional control, and blood pressure regulation phenotypes. Decreasing fertility rates worldwide with the concomitant increased proportion of first-born children highlights a potential reflection of birth order-related epigenomic states on changing disease incidence trends.

P095 Epigenetic clocks have the potential to predict future grip strength in males but not females

Background/Aims

Sarcopenia and muscle ageing are associated with substantial morbidity and mortality for the individual and significant costs to healthcare budgets. However, if we can identify those at particular risk of muscle decline it may be possible to intervene, prevent further deterioration and improve the musculoskeletal health of the ageing population. DNA methylation accumulates across the lifecourse and provides the basis for biological clocks, generating a measure of age acceleration (i.e. that an individual is biologically older or younger than their chronological age would suggest). An example is the GrimAge clock which was designed to estimate remaining longevity and thus may potentially represent a novel risk marker for muscle deterioration. We aimed to investigate whether there is an association between methylation-measured age acceleration and future grip strength in a group of community-dwelling older adults.

Methods

This study is based within the Hertfordshire Cohort Study. At baseline, participants attended research visits where health-related questionnaires were completed and blood samples were collected. DNA was extracted from peripheral blood leukocytes and DNA methylation at CpG sites was measured using the Infinium Human Methylation Beadchip arrays (Illumina Inc., San Diego, CA) (450k, n = 99 and 850k, n = 326). After pre-processing, GrimAge epigenetic age acceleration was measured, using the array-specific publicly available algorithms, and standardised to an SD scale. Grip strength was ascertained using the JAMAR dynamometer at baseline and follow-up. Linear regression was used to examine GrimAge acceleration in relation to grip strength at baseline and follow-up in unadjusted models and those adjusted for age, height and BMI.

Results

A total of 425 participants (213 males and 212 females) were included in our analyses. The mean age at baseline was 64.1 years (SD 2.6) for males and 65.9 years (SD 2.7) for females. The median follow-up time was 11.6 years (IQR 11.0-12.4) and mean GrimAge at baseline was 58.4 years (SD 5.6). Higher GrimAge acceleration was significantly associated with lower grip strength at baseline (β= -1.43kg [95% CI: -2.39,-0.47] per SD greater age acceleration in univariate model, p &lt; 0.01) in unadjusted and adjusted models and at follow-up (β= -1.25kg [-2.24,-0.26] per SD, p &lt; 0.02). No significant associations were observed in females.

Conclusion

Our results suggest that greater GrimAge acceleration, as a measure of biological age acceleration, is significantly associated with lower grip strength after approximately a decade of follow-up. However, this association was only observed in males and not in females. The GrimAge clock was designed using methylation surrogates of age-related plasma proteins and smoking pack years, and it may be that the variation in these was more marked in our male population compared to females. Further work is required to investigate and replicate the above association.

Disclosure

N.R. Fuggle: None. L. Westbury: None. F. Reswan: None. N. Graham: None. N. Kitaba: None. K.A. Ward: None. K.A. Ward: None. N. Harvey: None. J. Holloway: None. E. Dennison: None. C. Cooper: None.

Ascaris exposure and its association with lung function, asthma, and DNA methylation in Northern Europe

BACKGROUND

Ascaris infections, with a worldwide prevalence above 10%, can cause respiratory pathology. However, long-term effects on lung function in humans are largely unknown.

OBJECTIVE

We investigated the associations of Ascaris exposure with lung function, asthma, and DNA methylation.

METHODS

Serum Ascaris IgG antibodies were measured in 671 adults aged 18 to 47 years (46% women) from Aarhus, Bergen, and Tartu RHINESSA study centers. Seropositivity was defined as IgG above the 90th percentile. Linear and logistic regressions were used to analyze Ascaris seropositivity as associated with lung function and asthma, adjusted for age, height, and smoking and clustered by center. DNA methylation in blood was profiled by a commercial methylation assay.

RESULTS

Ascaris seropositivity was associated with lower FEV₁ (-247 mL; 95% CI, -460, -34) and higher odds for asthma (adjusted odds ratio, 5.84; 95% CI, 1.67, 20.37) among men but not women, also after further adjusting for house dust mite sensitivity, consistent across study centers. At a genome-wide level, Ascaris exposure was associated with 23 differentially methylated sites in men and 3 in women. We identified hypermethylation of the MYBPC1 gene, which can regulate airway muscle contraction. We also identified genes linked to asthma pathogenesis such as CRHR1 and GRK1, as well as a differentially methylated region in the PRSS22 gene linked to nematode infection.

CONCLUSION

Ascaris exposure was associated with substantially lower lung function and increased asthma risk among men. Seropositive participants had sex-specific differences in DNA methylation compared to the unexposed, thus suggesting that exposure may lead to sex-specific epigenetic changes associated with lung pathology.

Influence of Maternal Lifestyle and Diet on Perinatal DNA Methylation Signatures Associated With Childhood Arterial Stiffness at 8 to 9 Years

Supplemental Digital Content is available in the text.

Increases in aortic pulse wave velocity, a measure of arterial stiffness, can lead to elevated systolic blood pressure and increased cardiac afterload in adulthood. These changes are detectable in childhood and potentially originate in utero, where an adverse early life environment can alter DNA methylation patterns detectable at birth. Here, analysis of epigenome-wide methylation patterns using umbilical cord blood DNA from 470 participants in the Southampton’s Women’s Survey identified differential methylation patterns associated with systolic blood pressure, pulse pressure, arterial distensibility, and descending aorta pulse wave velocity measured by magnetic resonance imaging at 8 to 9 years. Perinatal methylation levels at 16 CpG loci were associated with descending aorta pulse wave velocity, with identified CpG sites enriched in pathways involved in DNA repair (P=9.03×10⁻¹¹). The most significant association was with cg20793626 methylation (within protein phosphatase, Mg2+/Mn2+ dependent 1D; β=−0.05 m/s/1% methylation change, [95% CI, −0.09 to −0.02]). Genetic variation was also examined but had a minor influence on these observations. Eight pulse wave velocity-linked dmCpGs were associated with prenatal modifiable risk factors, with cg08509237 methylation (within palmitoyl-protein thioesterase-2) associated with maternal oily fish consumption in early and late pregnancy. Lower oily fish consumption in early pregnancy modified the relationship between methylation and pulse wave velocity, with lower consumption strengthening the association between cg08509237 methylation and increased pulse wave velocity. In conclusion, measurement of perinatal DNA methylation signatures has utility in identifying infants who might benefit from preventive interventions to reduce risk of later cardiovascular disease, and modifiable maternal factors can reduce this risk in the child.