Epigenetic aging in newborns: role of maternal diet

Quantification of Epigenetic Aging in Public Health

Estimators of biological age hold promise for use in preventive medicine, for early detection of chronic conditions, and for monitoring the effectiveness of interventions aimed at improving population health. Among the promising biomarkers in this field are DNA methylation-based biomarkers, commonly referred to as epigenetic clocks. This review provides a survey of these clocks, with an emphasis on second-generation clocks that predict human morbidity and mortality. It explores the validity of epigenetic clocks when considering factors such as race, sex differences, lifestyle, and environmental influences. Furthermore, the review addresses the current challenges and limitations in this research area.

Bee Pollen Phytochemicals and Nutrients as Unequaled Pool of Epigenetic Regulators: Implications for Age-Related Diseases

Bee pollen is characterized by an exceptional diversity and abundance of micronutrients and bioactive phytochemicals. This richness remains very sparsely investigated, but accumulating evidence strongly supports a promising future for bee pollen in human nutrition and medicine. Epigenetic regulation is among the most compelling biomedical topics that remain completely untapped in bee pollen and bee derivative research. In our current research, we identified numerous ubiquitous compounds that are consistently present in this matrix, regardless of its botanical and geographical origins, and that have been well studied and documented as epigenetic regulators in recent years. Given the relative newness of both bee pollen biomedical research and epigenetic studies within nutritional, pharmaceutical, and medical sciences, this review aims to bridge these valuable fields and advance related experimental investigations. To the best of our knowledge, this is the first work that has aimed to comprehensively investigate the epigenetic modulatory potential of bee pollen compounds. Our findings have also unveiled several intriguing phenomena, such as a dual effect of the same compound depending on the cellular context or the effect of some compounds on the cross-generational heritability of epigenetic traits. Although experimental studies of epigenetic regulation by bee pollen as a whole or by its extract are still lacking, our current study clearly indicates that this research avenue is very promising and worth further investigations. We hope that our current work constitutes a foundational cornerstone of future investigations for this avenue of research.

Associations of epigenetic age acceleration at birth and age 12 years with adolescent cardiometabolic risk: the HOME study

BACKGROUND

Cardiometabolic risk factors among youth are rising. Epigenetic age acceleration, a biomarker for aging and disease-risk, has been associated with adiposity in children, but its association with other cardiometabolic risk markers remains understudied. We employed data from the Health Outcomes and Measures of the Environment (HOME) study, a prospective pregnancy and birth cohort in the greater Cincinnati metropolitan area, to examine whether accelerated epigenetic age at birth as well as accelerated epigenetic age and faster pace of biological aging at age 12 years were associated with higher cardiometabolic risk in adolescents.

RESULTS

After adjusting for potential confounders, including estimated cell type proportions, epigenetic gestational age acceleration at birth, derived from the Bohlin, Knight, and Haftorn clocks using cord blood DNA methylation data, was not associated with cardiometabolic risk z-scores or individual cardiometabolic risk score components (visceral fat, leptin to adiponectin ratio, HOMA-IR, triglycerides to HDL-C ratio, HbA1c, or systolic blood pressure) at age 12 years. We also did not observe any associations of epigenetic age acceleration, calculated with Horvath's skin and blood, Hannum's, and Wu's epigenetic clocks using peripheral blood at age 12 years, with these same cardiometabolic risk markers. In contrast, faster pace of biological aging was associated with higher cardiometabolic risk [βs (95% CIs)] cardiometabolic risk score 0.25 (0.07, 0.42); visceral fat 0.21 (0.05, 0.38); and hemoglobin A1c 0.23 (0.05, 0.41) per standard deviation increase in pace of biological aging. Faster pace of biological aging was also positively associated with systolic blood pressure, triglycerides to HDL-C ratio, HOMA-IR, and leptin to adiponectin ratio, although these associations were not statistically significant.

CONCLUSIONS

Our findings provide evidence that faster pace of biological aging was associated with higher cardiometabolic risk score, visceral fat, and HbA1c at age 12 years. Further research is needed to determine whether these associations persist from adolescence through adulthood.

Causal benefits of 25 dietary intakes on epigenetic ageing: a Mendelian randomisation study

DNA methylation GrimAge acceleration (DMGA) and intrinsic epigenetic age acceleration (IEAA) are important physiological markers for assessing the ageing process. Evidence from cross-sectional studies suggests that some dietary intake is associated with DMGA and IEAA. However, the causal relationship between them has yet to be elucidated. This Mendelian randomisation study uses genetic variants associated with different dietary intakes as instrumental variables to explore the causal benefits of multiple dietary intakes on DMGA and IEAA. Cheese intake, dark chocolate intake, average weekly red wine intake, dried fruit intake, fresh fruit intake, porridge intake, cereal intake, and liver intake had a negative causal association with DMGA, and poultry intake and doughnut intake had a positive causal association with DMGA (p < 0.05). Muesli and bran cereal intake had a negative causal association with IEAA, and pineapple intake had a positive causal association with IEAA (p < 0.05). Dietary intake positively causally associated with IEAA or DMGA may have accelerated biological ageing; conversely, dietary intake negatively causally associated with IEAA or DMGA may have contributed to delaying biological ageing. Based on genetic evidence, this study demonstrated some significant causal benefits of dietary intake on DMGA and IEAA, suggesting the possibility of intervening in DNA methylation acceleration and epigenetic age acceleration by adjusting these food intakes, thereby promoting health and delaying ageing. However, the findings of this study are exploratory and preliminary and need to be supported and validated by evidence from further clinical studies and mechanistic studies.

Maternal Adverse Childhood Experiences and Biological Aging During Pregnancy and in Newborns

Importance

Adverse childhood experiences (ACEs), potentially traumatic experiences occurring before the age of 18 years, are associated with epigenetic aging later in life and may be transmitted across generations.

Objective

To test evidence of the transmission of biological embedding of life experience across generations by analyzing maternal ACEs and epigenetic clocks measured in mothers during pregnancy and in their children at birth.

Design, Setting, and Participants

For this cross-sectional study, data from the Accessible Resource for Integrated Epigenomic Studies (ARIES) substudy of the Avon Longitudinal Study of Parents and Children (ALSPAC) were analyzed. The ALSPAC study recruited 14 541 women who gave birth in the Avon Health District in the UK between April 1, 1991, and December 31, 1992. The ARIES substudy comprised 1018 mother-offspring dyads based on the availability of DNA samples profiled in 2014. Epigenetic age was estimated using DNA methylation-based epigenetic clocks (including Horvath, Hannum, GrimAge, PhenoAge, and DunedinPACE) in mothers during pregnancy and the Knight and Bohlin cord blood epigenetic clocks in newborns. Analyses were performed between October 1, 2022, and November 30, 2023.

Exposures

A composite measure of maternal ACEs was the primary exposure in both maternal and offspring models; as a secondary analysis, individual ACEs were measured separately. The Edinburgh Postnatal Depression Scale (EPDS) was used to investigate depression during pregnancy as an exposure.

Main Outcomes and Measures

Changes in epigenetic age acceleration (EAA) were investigated as the primary outcome in maternal models during pregnancy. Changes in epigenetic gestational age acceleration (GAA) were the primary outcome in offspring analyses. Linear regression analyses were used to determine the association between maternal ACEs and both outcomes.

Results

This study included 883 mother-child dyads. The mean (SD) maternal age at delivery was 29.8 (4.3) years. Pregnant women with higher ACE scores exhibited higher GrimAge EAA (β, 0.22 [95% CI, 0.12 to 0.33] years; P < .001). Maternal ACEs were not associated with GAA in newborns using P < .05 as a cutoff to determine statistical significance. Depression was associated with higher GrimAge EAA (β, 0.06 [95% CI, 0.02 to 0.10] years; P = .01) in mothers during pregnancy, but not in newborns, and did not mediate the association between ACEs and EAA.

Conclusions and Relevance

The findings of this study suggest that maternal ACEs may be associated with epigenetic aging later in life, including during pregnancy, supporting a role for maternal ACEs in offspring development and health later in life.

Trauma, adversity, and biological aging: behavioral mechanisms relevant to treatment and theory

Although stress and adversity are largely universal experiences, people exposed to greater hardship are at increased risk for negative health consequences. Recent studies identify accelerated biological aging as a mechanism that could explain how trauma and adversity gives rise to poor health, and advances in this area of study coincide with technological innovations in the measurement of biological aging, particularly epigenetic profiles consistent with accelerated aging derived from DNA methylation. In this review, we provide an overview of the current literature examining how adversity might accelerate biological aging, with a specific focus on social and health behaviors. The most extensive evidence in this area suggests that health-compromising behaviors, particularly smoking, may partially explain the association between adversity and accelerated aging. Although there is relatively less published support for the role of social behaviors, emerging evidence points to the importance of social connection as a mechanism for future study. Our review highlights the need to determine the extent to which the associations from adversity to accelerated aging are consistent with causal processes. As we consider these questions, the review emphasizes methodological approaches from the causal inference literature that can help deepen our understanding of how stress and trauma might result in poor health. The use of these methodologies will help provide evidence as to which behavioral interventions might slow aging and improve health, particularly among populations that more often experience adversity and trauma.

Maternal Body Mass Index Associates with Prenatal Characteristics and Fecal Microbial Communities

The maternal microbiome plays a vital role in shaping pregnancy outcomes, but there remains a substantial gap in understanding its precise relationships to maternal health, particularly in relation to potential effects of body mass index (BMI) on gut microbial diversity. The aim of this observational study was to assess maternal characteristics in association with pre-pregnancy BMI and to further assess microbial diversity in association with specific maternal characteristics. Eighty-four pregnant women were recruited during their third trimester of pregnancy from various prenatal clinics across the state of Michigan. The participants completed an enrollment questionnaire including self-reported pre-pregnancy BMI; stool samples were collected to assess the fecal microbial community composition. Pre-pregnancy obesity (BMI 30+) was associated (univariably) with antibiotic use before pregnancy, ever smoked, lower education level, and being unmarried. The gut microbiota alpha diversity was significantly different for pregnant women by pre-pregnancy BMI category (normal, overweight, obese). The beta diversity was unique for the gut microbiotas of pregnant women within each BMI category, by education level, and by marital status. Multivariable models revealed that pre-pregnancy BMI, maternal education, marital status, and maternal age were associated with the microbial diversity of the gut microbiota during pregnancy. These results give new insight into the relationship between a woman's microbiome during pregnancy and their prenatal health, along with an understanding of the relationships between socioeconomic factors and microbial diversity.

Epigenetic age acceleration, neonatal morbidities, and neurobehavioral profiles in infants born very preterm

Epigenetic age acceleration is a risk factor for chronic diseases of ageing and may reflect aspects of biological ageing. However, few studies have examined epigenetic ageing during the early neonatal period in preterm infants, who are at heightened risk of developmental problems. We examined relationships between neonatal age acceleration, neonatal morbidities, and neurobehavioral domains among very preterm (<30 weeks gestation) infants to characterize whether infants with early morbidities or different neurobehavioral characteristics had accelerated or decelerated epigenetic ageing. This study uses data from the Neonatal Neurobehavior and Outcomes in Very Preterm Infants (NOVI) study, restricted to infants with data on variables assessed (n = 519). We used generalized estimating equations to test for differences in age acceleration associated with severe neonatal medical morbidities and neurobehavioral characteristics. We found that infants with neonatal morbidities, in particular, bronchopulmonary dysplasia (BPD), had accelerated epigenetic age - and some evidence that infants with hypertonicity and asymmetric reflexes had increased and decreased age acceleration, respectively. Adjustment for gestational age attenuated some associations, suggesting that the relationships observed may be driven by the duration of gestation. Our most robust finding shows that very preterm infants with neonatal morbidities (BPD in particular) exhibit age acceleration, but most neonatal neurobehavioral characteristics and morbidities are not associated with early life age acceleration. Lower gestational age at birth may be an upstream factor driving these associations.

Using Epigenetic Clocks to Characterize Biological Aging in Studies of Children and Childhood Exposures: a Systematic Review

Biological age, measured via epigenetic clocks, offers a unique and useful tool for prevention scientists to explore the short- and long-term implications of age deviations for health, development, and behavior. The use of epigenetic clocks in pediatric research is rapidly increasing, and there is a need to review the landscape of this work to understand the utility of these clocks for prevention scientists. We summarize the current state of the literature on the use of specific epigenetic clocks in childhood. Using systematic review methods, we identified studies published through February 2023 that used one of three epigenetic clocks as a measure of biological aging. These epigenetic clocks could either be used as a predictor of health outcomes or as a health outcome of interest. The database search identified 982 records, 908 of which were included in a title and abstract review. After full-text screening, 68 studies were eligible for inclusion. While findings were somewhat mixed, a majority of included studies found significant associations between the epigenetic clock used and the health outcome of interest or between an exposure and the epigenetic clock used. From these results, we propose the use of epigenetic clocks as a tool to understand how exposures impact biologic aging pathways and development in early life, as well as to monitor the effectiveness of preventive interventions that aim to reduce exposure and associated adverse health outcomes.

Maternal and Paternal Dietary Quality and Dietary Inflammation Associations with Offspring DNA Methylation and Epigenetic Biomarkers of Aging in the Lifeways Cross-Generation Study

BACKGROUND

Early-life nutritional exposures may contribute to offspring epigenetic modifications. However, few studies have evaluated parental dietary quality effects on offspring DNA methylation (DNAm).

OBJECTIVES

We aim to fill this gap by elucidating the influence of maternal and paternal whole-diet quality and inflammatory potential on offspring DNAm in the Lifeways Cross-generation cohort.

METHODS

Families (n = 1124) were recruited around 16 weeks of gestation in the Republic of Ireland between 2001 and 2003. Maternal dietary intake during the first trimester and paternal diet during the 12 previous months were assessed with an FFQ. Parental dietary inflammatory potential and quality were determined using the energy-adjusted Dietary Inflammatory Index (E-DII), the Healthy Eating Index-2015 (HEI-2015), and the maternal DASH score. DNAm in the saliva of 246 children at age nine was measured using the Illumina Infinium HumanMethylationEPIC array. DNAm-derived biomarkers of aging, the Pediatric-Buccal-Epigenetic clock and DNAm estimator of telomere length, were calculated. Parental diet associations with the DNAm concentrations of 850K Cytosine-phosphate-guanine sites (CpG sites) and with DNAm-derived biomarkers of aging were examined using an epigenome-wide association study and linear regressions, respectively.

RESULTS

Maternal HEI-2015 scores were inversely associated with DNAm at CpG site (cg21840035) located near the PLEKHM1 gene, whose functions involve regulation of bone development (β = -0.0036, per 1 point increase in the score; P = 5.6 × 10-8). Higher paternal HEI-2015 score was related to lower methylation at CpG site (cg22431767), located near cell signaling gene LUZP1 (β = -0.0022, per 1 point increase in the score, P = 4.1 × 10-8). There were no associations with parental E-DII and DASH scores, and no evidence of major effects on biomarkers of aging.

CONCLUSIONS

Parental dietary quality in the prenatal period, evaluated by the HEI-2015, may influence offspring DNAm during childhood. Further research to improve our understanding of parental nutritional programming is warranted.

Maternal plasma fatty acid patterns in mid-pregnancy and offspring epigenetic gestational age at birth

Maternal pregnancy fatty acid status is associated with child health. Epigenetic gestational age acceleration, referring to a discrepancy between chronological and epigenetic gestational age, may underlie these associations. Previous research suggests that analysing fatty acid patterns rather than individual fatty acids may overcome the caveat of missing synergistic or additive effects. Among 1226 mother-newborn pairs from the population-based Generation R Study, we examined the associations of three maternal plasma mid-pregnancy fatty acid patterns, identified by principal component analysis, with offspring epigenetic gestational age acceleration. This was estimated from cord blood DNA methylation data using the method developed by Bohlin. As a secondary analysis, we used the method developed by Knight to estimate epigenetic gestational age. The identified 'high n-6 polyunsaturated fatty acid,' 'monounsaturated and saturated fatty acid' and 'high n-3 polyunsaturated fatty acid' patterns were not associated with epigenetic gestational age acceleration in the main analyses. In sensitivity analyses restricted to 337 children born to mothers with more accurate pregnancy dating based on a regular menstrual cycle, a one standard-deviation-score higher maternal plasma 'high n-3 polyunsaturated fatty acid' pattern was associated with an epigenetic gestational age acceleration of 0.20 weeks (95% CI 0.06, 0.33), but only when using the Knight method. Thus, we found some evidence that a maternal plasma fatty acid pattern characterized by higher concentrations of n-3 polyunsaturated fatty acids may be associated with accelerated epigenetic gestational ageing. These findings depended on the method used and the accuracy of pregnancy dating and therefore need confirmation.

The Legacy of Parental Obesity: Mechanisms of Non-Genetic Transmission and Reversibility

While a dramatic increase in obesity and related comorbidities is being witnessed, the underlying mechanisms of their spread remain unresolved. Epigenetic and other non-genetic mechanisms tend to be prominent candidates involved in the establishment and transmission of obesity and associated metabolic disorders to offspring. Here, we review recent findings addressing those candidates, in the context of maternal and paternal influences, and discuss the effectiveness of preventive measures.

Epigenetics of type 2 diabetes mellitus and weight change - a tool for precision medicine?

Pioneering studies performed over the past few decades demonstrate links between epigenetics and type 2 diabetes mellitus (T2DM), the metabolic disorder with the most rapidly increasing prevalence in the world. Importantly, these studies identified epigenetic modifications, including altered DNA methylation, in pancreatic islets, adipose tissue, skeletal muscle and the liver from individuals with T2DM. As non-genetic factors that affect the risk of T2DM, such as obesity, unhealthy diet, physical inactivity, ageing and the intrauterine environment, have been associated with epigenetic modifications in healthy individuals, epigenetics probably also contributes to T2DM development. In addition, genetic factors associated with T2DM and obesity affect the epigenome in human tissues. Notably, causal mediation analyses found DNA methylation to be a potential mediator of genetic associations with metabolic traits and disease. In the past few years, translational studies have identified blood-based epigenetic markers that might be further developed and used for precision medicine to help patients with T2DM receive optimal therapy and to identify patients at risk of complications. This Review focuses on epigenetic mechanisms in the development of T2DM and the regulation of body weight in humans, with a special focus on precision medicine.

Epigenetic Aging in Early Life: Role of Maternal and Early Childhood Nutrition

PURPOSE OF REVIEW

Early life presents a pivotal period during which nutritional exposures are more likely to cause epigenetic modifications, which may impact an individual's health during adulthood. This article reviews the current evidence regarding maternal and early childhood nutritional exposures and their role in epigenetic aging.

RECENT FINDINGS

Maternal and early life consumption of diets higher in fiber, antioxidants, polyphenols, B vitamins, vitamin D, and ω-3 fatty acids is associated with slower epigenetic aging. Conversely, diets higher in glycemic load, fat, saturated fat, and ω-6 fatty acids demonstrate a positive association with epigenetic aging. Maternal and early life nutrition directly and indirectly influences epigenetic aging via changes in one-carbon metabolism, cardiometabolic health, and the microbiome. Clinical trials are warranted to determine the specific foods, dietary patterns, and dietary supplements that will normalize or lower epigenetic aging across the life course.

Batch-effect detection, correction and characterisation in Illumina HumanMethylation450 and MethylationEPIC BeadChip array data

Background

Genomic technologies can be subject to significant batch-effects which are known to reduce experimental power and to potentially create false positive results. The Illumina Infinium Methylation BeadChip is a popular technology choice for epigenome-wide association studies (EWAS), but presently, little is known about the nature of batch-effects on these designs. Given the subtlety of biological phenotypes in many EWAS, control for batch-effects should be a consideration.

Results

Using the batch-effect removal approaches in the ComBat and Harman software, we examined two in-house datasets and compared results with three large publicly available datasets, (1214 HumanMethylation450 and 1094 MethylationEPIC BeadChips in total), and find that despite various forms of preprocessing, some batch-effects persist. This residual batch-effect is associated with the day of processing, the individual glass slide and the position of the array on the slide. Consistently across all datasets, 4649 probes required high amounts of correction. To understand the impact of this set to EWAS studies, we explored the literature and found three instances where persistently batch-effect prone probes have been reported in abstracts as key sites of differential methylation. As well as batch-effect susceptible probes, we also discover a set of probes which are erroneously corrected. We provide batch-effect workflows for Infinium Methylation data and provide reference matrices of batch-effect prone and erroneously corrected features across the five datasets spanning regionally diverse populations and three commonly collected biosamples (blood, buccal and saliva).

Conclusions

Batch-effects are ever present, even in high-quality data, and a strategy to deal with them should be part of experimental design, particularly for EWAS. Batch-effect removal tools are useful to reduce technical variance in Infinium Methylation data, but they need to be applied with care and make use of post hoc diagnostic measures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-022-01277-9.

Maternal dietary fatty acid composition and newborn epigenetic aging-a geometric framework approach

BACKGROUND

Maternal nutrition is associated with epigenetic and cardiometabolic risk factors in offspring. Research in humans has primarily focused on assessing the impact of individual nutrients.

OBJECTIVES

We sought to assess the collective impact of maternal dietary MUFAs, PUFAs, and SFAs on epigenetic aging and cardiometabolic risk markers in healthy newborn infants using a geometric framework approach.

METHODS

Body fatness (n = 162), aortic intima-media thickness (aIMT; n = 131), heart rate variability (n = 118), and epigenetic age acceleration (n = 124) were assessed in newborn infants. Maternal dietary intake was cross-sectionally assessed in the immediate postpartum period via a validated 80-item self-administered FFQ. Generalized additive models were used to explore interactive associations of nutrient intake, with results visualized as response surfaces.

RESULTS

After adjustment for total energy intake, maternal age, gestational age, and sex there was a 3-way interactive association of MUFAs, PUFAs, and SFAs (P = 0.001) with newborn epigenetic aging. This suggests that the nature of each fat class association depends upon one another. Response surfaces revealed MUFAs were positively associated with newborn epigenetic age acceleration only at proportionately lower intakes of SFAs or PUFAs. We also demonstrate a potential beneficial association of omega-3 (n-3) PUFAs with newborn epigenetic age acceleration (P = 0.008). There was no significant association of fat class with newborn aIMT, heart rate variability, or body fatness.

CONCLUSIONS

In this study, we demonstrated an association between maternal dietary fat class composition and epigenetic aging in newborns. Future research should consider other characteristics such as the source of maternal dietary fatty acids.

Epigenetic aging biomarkers and occupational exposure to benzene, trichloroethylene and formaldehyde

Epigenetic aging biomarkers are associated with increased morbidity and mortality. We evaluated if occupational exposure to three established chemical carcinogens is associated with acceleration of epigenetic aging. We studied workers in China occupationally exposed to benzene, trichloroethylene (TCE) or formaldehyde by measuring personal air exposures prior to blood collection. Unexposed controls matched by age and sex were selected from nearby factories. We measured leukocyte DNA methylation (DNAm) in peripheral white blood cells using the Infinium HumanMethylation450 BeadChip to calculate five epigenetic aging clocks and DNAmTL, a biomarker associated with leukocyte telomere length and cell replication. We tested associations between exposure intensity and epigenetic age acceleration (EAA), defined as the residuals of regressing the DNAm aging biomarker on chronological age, matching factors and potential confounders. Median differences in EAA between exposure groups were tested using a permutation test with exact p-values. Epigenetic clocks were strongly correlated with age (Spearman r > 0.8) in all three occupational studies. There was a positive exposure-response relationship between benzene and the Skin-Blood Clock EAA biomarker: median EAA was -0.91 years in controls (n = 44), 0.78 years in workers exposed to <10 ppm (n = 41; mean benzene = 1.35 ppm; p = 0.034 vs. controls), and 2.10 years in workers exposed to ≥10 ppm (n = 9; mean benzene = 27.3 ppm; p = 0.019 vs. controls; p_trend = 0.0021). In the TCE study, control workers had a median Skin-Blood Clock EAA of -0.54 years (n = 71) compared to 1.63 years among workers exposed to <10 ppm of TCE (n = 27; mean TCE = 4.22 ppm; p = 0.035). We observed no evidence of EAA associations with formaldehyde exposure (39 controls, 31 exposed). Occupational benzene and TCE exposure were associated with increased epigenetic age acceleration measured by the Skin-Blood Clock. For TCE, there was some evidence of epigenetic age acceleration for lower exposures compared to controls. Our results suggest that some chemical carcinogens may accelerate epigenetic aging.

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BACKGROUND

Neonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.

OBJECTIVES

To describe the different types of investigations where neonatal HRV was used, study characteristics, and types of analyses performed.

ELIGIBILITY CRITERIA

Human neonates ≤1 month of corrected age.

SOURCES OF EVIDENCE

A protocol and search strategy of the literature was developed in collaboration with the McGill University Health Center's librarians and articles were obtained from searches in the Biosis, Cochrane, Embase, Medline and Web of Science databases published between 1 January 2000 and 1 July 2020.

CHARTING METHODS

A single reviewer screened for eligibility and data were extracted from the included articles. Information collected included the study characteristics and population, type of HRV analysis used (time domain, frequency domain, non-linear, heart rate characteristics (HRC) parameters) and clinical applications (physiological and pathological conditions, responses to various stimuli and outcome prediction).

RESULTS

Of the 286 articles included, 171 (60%) were small single centre studies (sample size <50) performed on term infants (n=136). There were 138 different types of investigations reported: physiological investigations (n=162), responses to various stimuli (n=136), pathological conditions (n=109) and outcome predictor (n=30). Frequency domain analyses were used in 210 articles (73%), followed by time domain (n=139), non-linear methods (n=74) or HRC analyses (n=25). Additionally, over 60 different measures of HRV were reported; in the frequency domain analyses alone there were 29 different ranges used for the low frequency band and 46 for the high frequency band.

CONCLUSIONS

Neonatal HRV has been used in diverse types of investigations with significant lack of consistency in analysis methods applied. Specific guidelines for HRV analyses in neonates are needed to allow for comparisons between studies.

Long-term Aspirin Use and Epigenetic Mitotic Clocks for Cancer Risk Prediction: Findings in Healthy Colon Mucosa and Recommendations for Future Epigenetic Aging Studies

BACKGROUND

Despite the known role of mitosis in colorectal cancer, previous associations of long-term aspirin use with suppressed cancer-related epigenetic aging did not involve epigenetic mitotic clocks. We investigated these relationships using three epigenetic mitotic clocks developed for cancer risk prediction: EpiTOC, EpiTOC2, and MiAge. We utilized publicly available HumanMethylationEPIC BeadChip data from 112 healthy colon (proximal and distal) mucosal samples taken at baseline (T1) and at 10-years follow-up (T2) from a screening cohort of 28 Polish women (11 non-users and 17 long-term [≥ 2 years] aspirin users). Mitotic clock values were divided by chronological age at each timepoint to obtain intrinsic rates (IRs). We evaluated differences in residuals of the mitotic clock IRs taken from linear mixed effects models adjusted for BMI, polyp status, and DNA methylation batch.

FINDINGS

EpiTOC, EpiTOC2 and MiAge were significantly correlated with chronological age (P < 0.05) with correlations ranging from 0.41 to 0.63. The EpiTOC, EpiTOC2 and MiAge clocks were strongly correlated with each other in proximal and distal samples (r > 0.79, P < 0.0001). We observed proximal within group median clock IR deceleration for EpiTOC (-0.0004 DNAm, P = 0.008), EpiTOC2 (-16 cell divisions, P = 0.009), and MiAge (-3 cell divisions, P = 0.002) for long-term aspirin users from T1 to T2 but not for non-users. In distal samples, only the long-term user MiAge IR was significantly deaccelerated (-3 cell divisions, P = 0.009).

CONCLUSIONS

Our observed findings support previously reported longitudinal associations of aspirin use with deceleration of other epigenetic age measures in the proximal colon. Our mitotic clock results suggest that cell proliferation could play a role in some aspirin relationships with epigenetic aging. Furthermore, the findings provide added impetus for establishing gold standards for epigenetic aging and consensus guidelines for more comprehensive reporting in future epigenetic aging cancer studies.

Epigenetic age acceleration and cardiovascular outcomes in school-age children: The Generation R Study

BACKGROUND

Hypertension and atherosclerosis may partly originate in early life. Altered epigenetic aging may be a mechanism underlying associations of early-life exposures and the development of cardiovascular risk factors in childhood. A discrepancy between chronological age and age predicted from neonatal DNA methylation data is referred to as age acceleration. It may either be positive, if DNA methylation age is older than clinical age, or negative, if DNA methylation age is younger than chronological age. We examined associations of age acceleration at birth ('gestational age acceleration'), and of age acceleration at school-age, with blood pressure and with intima-media thickness and distensibility of the common carotid artery, as markers of vascular structure and function, respectively, measured at age 10 years.

RESULTS

This study was embedded in the Generation R Study, a population-based prospective cohort study. We included 1115 children with information on cord blood DNA methylation and blood pressure, carotid intima-media thickness or carotid distensibility. Gestational age acceleration was calculated using the Bohlin epigenetic clock, which was developed specifically for cord blood DNA methylation data. It predicts gestational age based on methylation levels of 96 CpGs from HumanMethylation450 BeadChip. We observed no associations of gestational age acceleration with blood pressure, carotid intima-media thickness or carotid distensibility at age 10 years. In analyses among children with peripheral blood DNA methylation measured at age 6 (n = 470) and 10 (n = 449) years, we also observed no associations of age acceleration at these ages with the same cardiovascular outcomes, using the 'skin and blood clock,' which predicts age based on methylation levels at 391 CpGs from HumanMethylation450 BeadChip.

CONCLUSIONS

Our findings do not provide support for the hypothesis that altered epigenetic aging during the earliest phase of life is involved in the development of cardiovascular risk factors in childhood.

Multi-Omics Interpretation of Anti-Aging Mechanisms for ω-3 Fatty Acids

Aging is one of the hottest topics in biomedicine. Previous research suggested that ω-3 fatty acids have preventive effects on aging. However, most of previous studies on the anti-aging effects of ω-3 fatty acids are focused on clinical observations, and the anti-aging mechanisms of ω-3 fatty acids have not been fully elucidated. This stimulated our interest to use multi-omics data related to ω-3 fatty acids in order to interpret the anti-aging mechanisms of ω-3 fatty acids. First, we found that ω-3 fatty acids can affect methylation levels and expression levels of genes associated with age-related diseases or pathways in humans. Then, a Mendelian randomization analysis was conducted to determine whether there is a causal relationship between the effect of ω-3 fatty acids on blood lipid levels and variation in the gut microbiome. Our results indicate that the impact of ω-3 fatty acids on aging is partially mediated by the gut microbiome (including Actinobacteria, Bifidobacteria and Streptococcus). In conclusion, this study provides deeper insights into the anti-aging mechanisms of ω-3 fatty acids and supports the dietary supplementation of ω-3 fatty acids in aging prevention.

Maternal Dietary Quality and Dietary Inflammation Associations with Offspring Growth, Placental Development, and DNA Methylation

The ‘Developmental Origins of Health and Diseases’ hypothesis posits that prenatal maternal diet influences offspring growth and later life health outcomes. Dietary assessment has focused on selected nutrients. However, this approach does not consider the complex interactions between foods and nutrients. To provide a more comprehensive approach to public health, dietary indices have been developed to assess dietary quality, dietary inflammation and risk factors for non-communicable diseases. Thus far, their use in the context of placental development is limited and associations with offspring outcomes have been inconsistent. Although epidemiological studies have focused on the role of maternal diet on foetal programming, the underlying mechanisms are still poorly understood. Some evidence suggests these associations may be driven by placental and epigenetic changes. In this narrative review, we examine the current literature regarding relationships between key validated diet quality scores (Dietary Inflammatory Index [DII], Mediterranean diet [MD], Healthy Eating Index [HEI], Alternative Healthy Eating Index [AHEI], Dietary Approaches to Stop Hypertension [DASH], Glycaemic Index [GI] and Glycaemic Load [GL]) in pregnancy and birth and long-term offspring outcomes. We summarise findings, discuss potential underlying placental and epigenetic mechanisms, in particular DNA methylation, and highlight the need for further research and public health strategies that incorporate diet quality and epigenetics.

Determination of saliva epigenetic age in infancy, and its association with parental socio-economic characteristics and pregnancy outcomes

Epigenetic age acceleration (AA) has been associated with adverse environmental exposures and many chronic conditions. We estimated, in the NINFEA birth cohort, infant saliva epigenetic age, and investigated whether parental socio-economic position (SEP) and pregnancy outcomes are associated with infant epigenetic AA. A total of 139 saliva samples collected at on average 10.8 (range 7-17) months were used to estimate Horvath's DNA methylation age. Epigenetic AA was defined as the residual from a linear regression of epigenetic age on chronological age. Linear regression models were used to test the associations of parental SEP and pregnancy outcomes with saliva epigenetic AA. A moderate positive association was found between DNA methylation age and chronological age, with the median absolute difference of 6.8 months (standard deviation [SD] 3.9). The evidence of the association between the indicators of low SEP and epigenetic AA was weak; infants born to unemployed mothers or with low education had on average 1 month higher epigenetic age than infants of mothers with high education and employment (coefficient 0.78 months, 95% confidence intervals [CIs]: -0.79 to 2.34 for low/medium education; 0.96, 95% CI: -1.81 to 3.73 for unemployment). There was no evidence for association of gestational age, birthweight or caesarean section with infant epigenetic AA. Using the Horvath's method, DNA methylation age can be fairly accurately predicted from saliva samples already in the first months of life. This study did not reveal clear associations between either pregnancy outcomes or parental socio-economic characteristics and infant saliva epigenetic AA.

Pathophysiological adaptations of resistance arteries in rat offspring exposed in utero to maternal obesity is associated with sex-specific epigenetic alterations

BACKGROUND/OBJECTIVES

Maternal obesity impacts vascular functions linked to metabolic disorders in offspring, leading to cardiovascular diseases during adulthood. Even if the relation between prenatal conditioning of cardiovascular diseases by maternal obesity and vascular function begins to be documented, little is known about resistance arteries. They are of particular interest because of their specific role in the regulation of local blood flow. Then our study aims to determine if maternal obesity can directly program fetal vascular dysfunction of resistance arteries, independently of metabolic disorders.

METHODS

With a model of rats exposed in utero to mild maternal diet-induced obesity (OMO), we investigated third-order mesenteric arteries of 4-month old rats in absence of metabolic disorders. The methylation profile of these vessels was determined by reduced representation bisulfite sequencing (RRBS). Vascular structure and reactivity were investigated using histomorphometry analysis and wire-myography. The metabolic function was evaluated by insulin and glucose tolerance tests, plasma lipid profile, and adipose tissue analysis.

RESULTS

At 4 months of age, small mesenteric arteries of OMO presented specific epigenetic modulations of matrix metalloproteinases (MMPs), collagens, and potassium channels genes in association with an outward remodeling and perturbations in the endothelium-dependent vasodilation pathways (greater contribution of EDHFs pathway in OMO males compared to control rats, and greater implication of PGI₂ in OMO females compared to control rats). These vascular modifications were detected in absence of metabolic disorders.

CONCLUSIONS

Our study reports a specific methylation profile of resistance arteries associated with vascular remodeling and vasodilation balance perturbations in offspring exposed in utero to maternal obesity, in absence of metabolic dysfunctions.