Pregnancy is linked to faster epigenetic aging in young women

Epigenetic ageing clocks: statistical methods and emerging computational challenges

Over the past decade, epigenetic clocks have emerged as powerful machine learning tools, not only to estimate chronological and biological age but also to assess the efficacy of anti-ageing, cellular rejuvenation and disease-preventive interventions. However, many computational and statistical challenges remain that limit our understanding, interpretation and application of epigenetic clocks. Here, we review these computational challenges, focusing on interpretation, cell-type heterogeneity and emerging single-cell methods, aiming to provide guidelines for the rigorous construction of interpretable epigenetic clocks at cell-type and single-cell resolution.

Pregnancy-induced metabolic reprogramming and regenerative responses to pro-aging stresses

Pregnancy is associated with physiological adaptations that affect virtually all organs, enabling the mother to support the growing fetus and placenta while withstanding the demands of pregnancy. As a result, mammalian pregnancy is a unique state that exerts paradoxical effects on maternal health. On one hand, the metabolic stress induced by pregnancy can accelerate aging and functional decline in organs. On the other hand, pregnancy activates metabolic programming and tissue regenerative responses that can reverse age-related impairments. In this sense, the oocyte-to-blastocyst transition is not the only physiological reprogramming event in the mammalian body, as pregnancy-induced regeneration could constitute a second physiological reprogramming event. Here, we review findings on how pregnancy dualistically leads to aging and rejuvenation in the maternal body.

Cardiac remodelling, recognition memory deficits and accelerated ageing in a rat model of gestational diabetes

AIMS/HYPOTHESIS

Women with prior gestational diabetes mellitus (GDM) have higher incidence of age-associated diseases, including type 2 diabetes, CVD and cognitive impairment. Human studies cannot readily determine whether GDM causes these conditions or the underlying mechanisms. Here we used a well-validated rat model of GDM to address these questions.

METHODS

Rats with beta cell-specific expression of human amylin, a pancreatic hormone, were used as a GDM model. Five-month-old female rats were randomly assigned to no-pregnancy, one-pregnancy and two-pregnancies experimental groups. GTTs and transthoracic echocardiography were performed at baseline and during the postpartum period. At 18 months of age, the novel object recognition test was administered, followed by euthanasia and organ collection.

RESULTS

All female rats developed glucose intolerance and showed cardiac remodelling and impaired left ventricular relaxation with ageing. Glucose intolerance was exacerbated in rats with prior GDM pregnancies compared with nulliparous rats, with significant differences starting at 9 months of age. However, blood glucose levels were comparable in the three groups during the course of the study. Rats with two GDM-complicated pregnancies had increased left ventricular mass compared with the other groups following the second pregnancy and until the end of the study. At 18 months of age, rats with prior GDM pregnancies presented aggravated demyelination, particularly in the hippocampus and mid-brain region, oxidative stress and neuroinflammation, and had a lower recognition index in the novel object recognition test compared with nulliparous rats. Higher parity exacerbated these effects. Shorter telomeres and reduced mitochondrial DNA content, two hallmarks of biological ageing, were found in the brain, heart and pancreas of rats with prior GDM.

CONCLUSIONS/INTERPRETATION

These findings support the concept that GDM is a sex-specific risk factor for ageing-related diseases, and point to accelerated cellular ageing as a contributing mechanism.

DATA AVAILABILITY

Cardiac echocardiography and GTT data are available at Dataverse under the identifier https://doi.org/10.7910/DVN/R2HITG.

Epigenetic biomarkers of socioeconomic status are associated with age-related chronic diseases and mortality in older adults

Later-life health is patterned by socioeconomic influences across the lifecourse. However, the pathways underlying the biological embedding of socioeconomic status (SES) and its consequences on downstream morbidity and mortality are not fully understood. Epigenetic markers like DNA methylation (DNAm) may be promising surrogates of underlying biological processes that can enhance our understanding of how SES shapes population health. Studies have shown that SES is associated with epigenetic aging measures, but few have examined relationships between early and later-life SES and DNAm sites across the epigenome. In this study, we trained and tested DNAm-based surrogates, or "biomarkers," of childhood and adult SES in two large, multiracial/ethnic samples of older adults-the Health and Retirement Study (n = 3,527) and the Multi-Ethnic Study of Atherosclerosis (n = 1,182). Both biomarkers were associated with downstream morbidity and mortality, and these associations persisted after controlling for measured SES, and in some cases, epigenetic aging clocks. Both childhood and adult SES biomarker CpG sites were enriched for genomic features that regulate gene expression (e.g. DNAse hypersensitivity sites and enhancers) and were implicated in prior epigenome-wide studies of inflammation, aging, and chronic disease. Distinct patterns also emerged between childhood CpGs and immune system dysregulation and adult CpGs and metabolic functioning, health behaviors, and cancer. Results suggest DNAm-based surrogate biomarkers of SES may be useful proxies for unmeasured social exposures that can augment our understanding of the biological mechanisms between social disadvantage and downstream health.

Prenatal sex determination illuminates the unusual adult sex ratio of a group-living lemur

Most mammals, including humans, exhibit even or slightly male-biased birth sex ratios (BSRs) and female-biased adult sex ratios (ASRs) much later in life due to higher male mortality rates. The group-living primates of Madagascar are unusual in this respect because they lack female-biased ASRs, but it is unknown whether this is the result of skewed BSRs or sex-specific disappearance patterns. Using long-term demographic data from wild red-fronted lemurs (Eulemur rufifrons), we analysed their sex ratio dynamics across the lifespan. We assessed BSR via prenatal sex determination using maternal faecal oestrogen metabolite measurements during late pregnancy, confirming a visually determined equal sex ratio three months after birth, and indicating no early sex-specific mortality. Demographic analyses additionally disclosed higher female disappearance within the first 8 years of age, likely associated with reproductive effort early in life. Thereby, adult male survival had the greatest positive effect on the ASR. Our study offers a rare perspective on the dynamics of age- and sex-specific disappearance in a wild primate population, whose sex-reversed patterns may also contribute to a more general understanding of the mechanisms generating sex-biased mortality.

Reproductive factors and biological aging: the association with all-cause and cause-specific premature mortality

STUDY QUESTION

Are reproductive factors associated with biological aging, and does biological aging mediate the associations of reproductive factors with premature mortality?

SUMMARY ANSWER

Multiple reproductive factors are related to phenotypic age acceleration (PhenoAge-Accel), while adherence to a healthy lifestyle mitigates these harmful effects; PhenoAge-Accel mediated the associations between reproductive factors and premature mortality.

WHAT IS KNOWN ALREADY

Accelerated aging is a key contributor to mortality, but knowledge about the effect of reproductive factors on aging is limited.

STUDY DESIGN, SIZE, DURATION

This prospective cohort study included 223 729 women aged 40-69 years from the UK biobank in 2006-2010 and followed up until 12 November 2021.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Reproductive factors were collected through a touchscreen questionnaire. Biological aging was assessed through PhenoAge-Accel. Multiple linear regression models were used to examine the relationships of reproductive factors with PhenoAge-Accel and estimate the modified effect of a healthy lifestyle. Furthermore, we applied mediation analysis to explore the mediating role of PhenoAge-Accel in the associations between reproductive factors and premature mortality.

MAIN RESULTS AND THE ROLE OF CHANCE

Early menarche (<12 years vs 13 years, β: 0.37, 95% CI: 0.30, 0.44), late menarche (≥15 years vs 13 years, β: 0.18, 95% CI: 0.11, 0.25), early menopause (<45 years vs 50-51 years, β: 0.62, 95% CI: 0.51, 0.72), short reproductive lifespan (<30 years vs 35-39 years, β: 0.81, 95% CI: 0.70, 0.92), nulliparity (vs two live births, β: 0.36, 95% CI: 0.30, 0.43), high parity (≥4 vs 2 live births, β: 0.49, 95% CI: 0.40, 0.59), early age at first live birth (<20 years vs 25-29 years, β: 0.66, 95% CI: 0.56, 0.75), and stillbirth (β: 0.51, 95% CI: 0.36, 0.65) were associated with increased PhenoAge-Accel. Furthermore, PhenoAge-Accel mediated 6.0%-29.7% of the associations between reproductive factors and premature mortality. Women with an unfavorable lifestyle and reproductive risk factors had the highest PhenoAge-Accel compared to those with a favorable lifestyle and without reproductive risk factors.

LIMITATIONS, REASONS FOR CAUTION

The participants in the UK Biobank were predominantly of White ethnicity; thus, caution is warranted when generalizing these findings to other ethnic groups.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings reveal the harmful effects of multiple reproductive factors on biological aging and the mediating role of biological aging in the associations between reproductive factors and premature mortality. They highlight the significance of adhering to a healthy lifestyle to slow biological aging as a potential way to reduce premature mortality among women with reproductive risk factors.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the National Natural Science Foundation of China (82003479, 82073660, 72204215), Hubei Provincial Natural Science Foundation of China (2023AFB663), Zhejiang Province Public Welfare Technology Application Research Project (GF22H269155), and China Postdoctoral Science Foundation (2019M662646, 2020T130220). The authors have no competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Genetics of female and male reproductive traits and their relationship with health, longevity and consequences for offspring

Substantial shifts in reproductive behaviors have recently taken place in many high-income countries including earlier age at menarche, advanced age at childbearing, rising childlessness and a lower number of children. As reproduction shifts to later ages, genetic factors may become increasingly important. Although monogenic genetic effects are known, the genetics underlying human reproductive traits are complex, with both causal effects and statistical bias often confounded by socioeconomic factors. Here, we review genome-wide association studies (GWASs) of 44 reproductive traits of both female and male individuals from 2007 to early 2024, examining reproductive behavior, reproductive lifespan and aging, infertility and hormonal concentration. Using the GWAS Catalog as a basis, from 159 relevant studies, we isolate 37 genes that harbor association signals for four or more reproductive traits, more than half of which are linked to rare Mendelian disorders, including ten genes linked to reproductive-related disorders: FSHB, MCM8, DNAH2, WNT4, ESR1, IGSF1, THRB, BRWD1, CYP19A1 and PTPRF. We also review the relationship of reproductive genetics to related health and behavioral traits, aging and longevity and the effect of parental age on offspring outcomes as well as reflecting on limitations, open questions and challenges in this fast-moving field.

Aging drives a program of DNA methylation decay in plant organs

How organisms age is a question with broad implications for human health. In mammals, DNA methylation is a biomarker for biological age, which may predict age more accurately than date of birth. However, limitations in mammalian models make it difficult to identify mechanisms underpinning age-related DNA methylation changes. Here, we show that the short-lived model plant Arabidopsis thaliana exhibits a loss of epigenetic integrity during aging, causing heterochromatin DNA methylation decay and the expression of transposable elements. We show that the rate of epigenetic aging can be manipulated by extending or curtailing lifespan, and that shoot apical meristems are protected from this aging process. We demonstrate that a program of transcriptional repression suppresses DNA methylation maintenance pathways during aging, and that mutants of this mechanism display a complete absence of epigenetic decay. This presents a new paradigm in which a gene regulatory program sets the rate of epigenomic information loss during aging.

A feminine advantage in the domain of harm: a review and path forward

Despite well-documented disparities disadvantaging women (e.g. discrepancies between men and women in salaries and leadership roles), we argue that there are contexts in which disparities disadvantage men. We review the literature suggesting harm to women is perceived as more severe and unacceptable than identical harm to men, a bias potentially rooted in evolutionary, base rate, stereotype-based and cultural shift explanations. We explore how these biases manifest in protective responses toward women and harsher judgements toward men, particularly in contexts of victimization and perpetration. Our review aims to complement the existing literature on gender biases by presenting a balanced view that acknowledges men and women face unique challenges. By understanding these biases, we hope to foster a more equitable discourse on gender and harm, encouraging empathy and validation of suffering irrespective of gender. This holistic approach aims to de-escalate gender-based conflicts and promote effective interventions for both men and women.

Association of a pace of aging epigenetic clock with rate of cognitive decline in the Framingham Heart Study Offspring Cohort

INTRODUCTION

The geroscience hypothesis proposes systemic biological aging is a root cause of cognitive decline.

METHODS

We analyzed Framingham Heart Study Offspring Cohort data (n = 2296; 46% male; baseline age M = 62, SD = 9, range = 25-101 y). We measured cognitive decline across two decades of neuropsychological-testing follow-up. We measured pace of aging using the DunedinPACE epigenetic clock. Analysis tested if participants with faster DunedinPACE values experienced more rapid cognitive decline compared with those with slower DunedinPACE values.

RESULTS

Participants with faster DunedinPACE had poorer cognitive functioning at baseline and experienced more rapid cognitive decline over follow-up. Results were robust to confounders and consistent across population strata. Findings were similar for the PhenoAge and GrimAge epigenetic clocks.

DISCUSSION

Faster pace of aging is a risk factor for preclinical cognitive decline. Metrics of biological aging may inform risk stratification in clinical trials and prognosis in patient care.

Highlights

Faster DunedinPACE is associated with preclinical cognitive aging.Higher baseline cognition was protective of DunedinPACE-associated cognitive decline.The DunedinPACE association with cognitive decline explained a fourth of dementia risk.

Mode of delivery predicts postpartum maternal leukocyte telomere length

BACKGROUND

Recent studies have suggested that pregnancy accelerates biologic aging, yet little is known about how biomarkers of aging are affected by events during the peripartum period. Given that immune shifts are known to occur following surgery, we explored the relation between mode of delivery and postpartum maternal leukocyte telomere length (LTL), a marker of biologic aging.

STUDY DESIGN

Postpartum maternal blood samples were obtained from a prospective cohort of term, singleton livebirths without hypertensive disorders or peripartum infections between 2012 and 2018. The primary outcome was postpartum LTLs from one blood sample drawn between postpartum week 1 and up to 6 months postpartum, measured from thawed frozen peripheral blood mononuclear cells using quantitative PCR in basepairs (bp). Multivariable linear regression models compared LTLs between vaginal versus cesarean births, adjusting for age, body mass index, and nulliparity as potential confounders. Analyses were conducted in two mutually exclusive groups: those with LTL measured postpartum week 1 and those measured up to 6 months postpartum. Secondarily, we compared multiomics by mode of delivery using machine-learning methods to evaluate whether other biologic changes occurred following cesarean. These included transcriptomics, metabolomics, microbiomics, immunomics, and proteomics (serum and plasma).

RESULTS

Of 67 included people, 50 (74.6 %) had vaginal and 17 (25.4 %) had cesarean births. LTLs were significantly shorter after cesarean in postpartum week 1 (5755.2 bp cesarean versus 6267.8 bp vaginal, p = 0.01) as well as in the later draws (5586.6 versus 5945.6 bp, p = 0.04). After adjusting for confounders, these differences persisted in both week 1 (adjusted beta -496.1, 95 % confidence interval [CI] -891.1, -101.1, p = 0.01) and beyond (adjusted beta -396.8; 95 % CI -727.2, -66.4. p = 0.02). Among the 15 participants who also had complete postpartum multiomics data available, there were predictive signatures of vaginal versus cesarean births in transcriptomics (cell-free [cf]RNA), metabolomics, microbiomics, and proteomics that did not persist after false discovery correction.

CONCLUSION

Maternal LTLs in postpartum week 1 were nearly 500 bp shorter following cesarean. This difference persisted several weeks postpartum, even though other markers of inflammation had normalized. Mode of delivery should be considered in any analyses of postpartum LTLs and further investigation into this phenomenon is warranted.