Publications by authors named "MacIsaac J"

Caloric restriction (CR) slows biological aging and prolongs healthy lifespan in model organisms. Findings from the CALERIE randomized, controlled trial of long-term CR in healthy, nonobese humans broadly supports a similar pattern of effects in humans. To expand our understanding of the molecular pathways and biological processes underpinning CR effects in humans, we generated a series of genomic datasets from stored biospecimens collected from n = 218 participants during the trial.

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Saliva is a widely used sample in epigenetic research with children due to its non-invasive nature. Since DNA methylation (DNAm) profile is cell type (CT) specific, salivary DNAm associations with exposures may be influenced by CT compositions, which is highly variable in saliva as it contains immune and buccal epithelial cells (BEC). Reference-based CT deconvolution and statistically adjusting estimated CT in DNAm analyses have become an increasingly common practice.

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Article Synopsis
  • * The study assesses the effects of prenatal and postnatal stress and depression on DNA methylation in newborns and 12-month-old children using the CHILD cohort, measuring stress and depression at multiple time points.
  • * Results showed significant associations between both prenatal and postnatal stress/depression and changes in DNA methylation at specific CpG sites in the newborn's cord blood and in blood from 12-month-old children, suggesting a biological impact of maternal mental health on child development.
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  • The study hypothesizes that better cardiorespiratory fitness (CRF) can slow down aging, especially in people with chronic airflow limitation (CAL).
  • Researchers analyzed DNA methylation and conducted exercise tests on 78 participants aged 40 and older to see how CRF impacts biological aging.
  • Findings showed that higher initial CRF was linked to slower aging according to various epigenetic markers, suggesting that improving CRF could benefit health in those with chronic respiratory issues.
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Caloric restriction (CR) slows biological aging and prolongs healthy lifespan in model organisms. Findings from CALERIE-2 - the first ever randomized, controlled trial of long-term CR in healthy, non-obese humans - broadly supports a similar pattern of effects in humans. To expand our understanding of the molecular pathways and biological processes underpinning CR effects in humans, we generated a series of genomic datasets from stored biospecimens collected from n=218 participants during the trial.

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We examined whether prenatal exposure to two classes of endocrine-disrupting chemicals (EDCs) was associated with infant epigenetic age acceleration (EAA), a DNA methylation biomarker of aging. Participants included 224 maternal-infant pairs from a Canadian pregnancy cohort study. Two bisphenols and 12 phthalate metabolites were measured in maternal second trimester urines.

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Early-life adversity increases the risk of health problems. Interventions supporting protective and responsive caregiving offer a promising approach to attenuating adversity-induced changes in stress-sensitive biomarkers. This study tested whether participation in an evidence-based dyadic psychosocial intervention, child-parent psychotherapy (CPP), was related to lower epigenetic age acceleration, a trauma-sensitive biomarker of accelerated biological aging that is associated with later health impairment, in a sample of children with trauma histories.

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Article Synopsis
  • The Illumina MethylationEPIC BeadChip microarray platform has two versions (v1.0 and v2.0), which show high correlation overall but varying results at the probe level for tools assessing DNA methylation effects.
  • Research using blood samples from different adult age groups found that samples clustered more by the EPIC version used than by other characteristics, indicating significant differences in data outputs between the two versions.
  • The study emphasizes the need to consider which EPIC version is used when analyzing data for meta-analyses and longitudinal studies, as these differences can impact findings in epigenome-wide association studies (EWAS).
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Background: DNA methylation may be a link between HIV, aging, and the increased risk of lung comorbidities. We investigated whether bronchoalveolar lavage (BAL) cells of people living with HIV (PLWH) demonstrate epigenetic disruptions and advanced epigenetic aging.

Methods: BAL cell DNA methylation from 25 PLWH and 16 HIV-uninfected individuals were tested for differential methylation of Alu and LINE-1 sites, markers of aging.

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Objective: Youth-onset type 2 diabetes (T2D) is physiologically distinct from adult-onset, but it is not clear how the two diseases differ at a molecular level. In utero exposure to maternal type 2 diabetes (T2D) is known to be a specific risk factor for youth-onset T2D. DNA methylation (DNAm) changes associated with T2D but which differ between youth- and adult-onset might delineate the impacts of T2D development at different ages and could also determine the contribution of exposure to in utero diabetes.

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Background: The effects of inhaled corticosteroids (ICS) on healthy airways are poorly defined.

Objectives: To delineate the effects of ICS on gene expression in healthy airways, without confounding caused by changes in disease-related genes and disease-related alterations in ICS responsiveness.

Methods: Randomized open-label bronchoscopy study of high-dose ICS therapy in 30 healthy adult volunteers randomized 2:1 to (i) fluticasone propionate 500 mcg bd daily or (ii) no treatment, for 4 weeks.

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Previous research has found that living in a disadvantaged neighborhood is associated with poor health outcomes. Living in disadvantaged neighborhoods may alter inflammation and immune response in the body, which could be reflected in epigenetic mechanisms such as DNA methylation (DNAm). We used robust linear regression models to conduct an epigenome-wide association study examining the association between neighborhood deprivation (Area Deprivation Index; ADI), and DNAm in brain tissue from 159 donors enrolled in the Emory Goizueta Alzheimer's Disease Research Center (Georgia, USA).

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A central prediction of evolutionary theory is that energy invested into reproduction comes at the expense of somatic maintenance and repair, accelerating biological aging. Supporting this prediction are findings that high fertility among women predicts shorter lifespan and poorer health later in life. However, biological aging is thought to begin before age-related health declines, limiting the applicability of morbidity and mortality for studying the aging process earlier in life.

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Background: Evidence suggests that prenatal air pollution exposure alters DNA methylation (DNAm), which could go on to affect long-term health. It remains unclear whether DNAm alterations present at birth persist through early life. Identifying persistent DNAm changes would provide greater insight into the molecular mechanisms contributing to the association of prenatal air pollution exposure with atopic diseases.

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Maternal stress and depression during pregnancy and the first year of the infant's life affect a large percentage of mothers. Maternal stress and depression have been associated with adverse fetal and childhood outcomes as well as differential child DNA methylation (DNAm). However, the biological mechanisms connecting maternal stress and depression to poor health outcomes in children are still largely unknown.

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Caloric restriction (CR) modifies lifespan and aging biology in animal models. The Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE™) 2 trial tested translation of these findings to humans. CALERIE™ randomized healthy, nonobese men and premenopausal women (age 21-50y; BMI 22.

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In humans, DNA methylation (DNAm) based estimators of telomere length (TL) have been shown to better predict TL-associated variables (e.g., age, sex, and mortality) than TL itself.

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Di(2-ethylhexyl) phthalate (DEHP) is a common plasticizer that can affect immune system development and susceptibility to infection. Aging processes (measured as epigenetic age acceleration (EAA)) may mediate the immune-related effects of prenatal exposure to DEHP. This study's objective was to examine associations between prenatal DEHP exposure, EAA at three months of age, and the number of upper respiratory infections (URIs) from 12 to 18 months of age using a sample of 69 maternal-child pairs from a Canadian pregnancy cohort.

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Background: While ageing is associated with increased insulin resistance (IR), the molecular mechanisms underlying increased IR in the muscle, the primary organ for glucose clearance, have yet to be elucidated in older individuals. As epigenetic processes are suggested to contribute to the development of ageing-associated diseases, we investigated whether differential DNA methylation was associated with IR in human primary muscle stem cells (myoblasts) from community-dwelling older individuals.

Methods: We measured DNA methylation (Infinium HumanMethylationEPIC BeadChip) in myoblast cultures from vastus lateralis biopsies (119 males/females, mean age 78.

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Background: Socioeconomic status (SES) gradients in health are well-documented, and while biological pathways are incompletely understood, chronic inflammation and accelerated immune aging (immunosenescence) among lower SES individuals have been implicated. However, previous findings have come from samples in higher income countries, and it is unclear how generalizable they are to lower- and middle-income countries (LMIC) with different infectious exposures and where adiposity-an important contributor to chronic inflammation-might show different SES patterning. To address this gap, we explored associations between SES and inflammation and immunosenescence in a sample of women in Cebu, Philippines.

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Background: In the first year of life, DNA methylation (DNAm) patterns are established and are particularly susceptible to exposure-induced changes. Some of these changes may leave lasting effects by persistently altering gene expression or cell type composition or function, contributing to disease.

Objectives: In this discovery study, we investigated DNAm associations with sensitization to peanut, egg, or cow's milk and hypothesized that genes demonstrating DNAm differences in immune cells may play a role in the development of food sensitization.

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Household air pollution caused by inefficient cooking practices causes 4 million deaths a year worldwide. In Nepal, 86% of the rural population use solid fuels for cooking. Over 25% of premature deaths associated with air pollution are respiratory in nature.

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Article Synopsis
  • This study explores how early-life infectious exposures may influence biological aging, using DNA methylation markers to assess changes that affect future health and life expectancy.
  • The research analyzed data from 1,450 participants in a long-term health survey, focusing on their health during infancy and how that links to biological aging in their young adulthood.
  • Results indicated that higher early-life infection rates and certain birth conditions were linked to slower biological aging, suggesting a complex relationship between early infections and long-term health outcomes that needs further investigation.
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