Setting the trajectory: racial disparities in newborn telomere length

Telomere dynamics and reproduction

The oocyte, a long-lived, postmitotic cell, is the locus of reproductive aging in women. Female germ cells replicate only during fetal life and age throughout reproductive life. Mechanisms of oocyte aging include the accumulation of oxidative damage, mitochondrial dysfunction, and disruption of proteins, including cohesion. Nobel Laureate Bob Edwards also discovered a "production line" during oogonial replication in the mouse, wherein the last oocytes to ovulate in the adult-derived from the last oogonia to exit mitotic replication in the fetus. On the basis of this, we proposed a two-hit "telomere theory of reproductive aging" to integrate the myriad features of oocyte aging. The first hit was that oocytes remaining in older women traversed more cell cycles during fetal oogenesis. The second hit was that oocytes accumulated more environmental and endogenous oxidative damage throughout the life of the woman. Telomeres (Ts) could mediate both of these aspects of oocyte aging. Telomeres provide a "mitotic clock," with T attrition an inevitable consequence of cell division because of the end replication problem. Telomere's guanine-rich sequence renders them especially sensitive to oxidative damage, even in postmitotic cells. Telomerase, the reverse transcriptase that restores Ts, is better at maintaining than elongating T. Moreover, telomerase remains inactive during much of oogenesis and early development. Oocytes are left with short Ts, on the brink of viability. In support of this theory, mice with induced T attrition and women with naturally occurring telomeropathy suffer diminished ovarian reserve, abnormal embryo development, and infertility. In contrast, sperm are produced throughout the life of the male by a telomerase-active progenitor, spermatogonia, resulting in the longest Ts in the body. In mice, cleavage-stage embryos elongate Ts via "alternative lengthening of telomeres," a recombination-based mechanism rarely encountered outside of telomerase-deficient cancers. Many questions about Ts and reproduction are raised by these findings: does the "normal" T attrition observed in human oocytes contribute to their extraordinarily high rate of meiotic nondisjunction? Does recombination-based T elongation render embryos susceptible to mitotic nondisjunction (and mosaicism)? Can some features of Ts serve as markers of oocyte quality?

Early origins of health and disease risk: The case for investigating adverse exposures and biological aging in utero, across childhood, and into adolescence

In this article, we suggest that aging and development are two sides of the same coin, and that developing a comprehensive understanding of health and disease risk requires examining age-related processes occurring throughout the earliest years of life. Compared to other periods in life, during this early period of acute vulnerability, when children's biological and regulatory systems are developing, biological aging occurs most rapidly. We review theory and empirical research suggesting that processes of development and aging are intricately linked, and that early adversity may program biological parameters for accelerated aging and disease risk early in life, even though clinical signs of age-related disease onset may not be evident until many years later. Following from this, we make the case for widespread incorporation of biological aging constructs into child development research.

Sub-optimal maternal gestational gain is associated with shorter leukocyte telomere length at birth in a predominantly Latinx cohort of newborns

OBJECTIVE

To assess in utero exposures associated with leukocyte telomere length (LTL) at birth and maternal LTL in a primarily Latinx birth cohort.

STUDY DESIGN

Mothers and newborns were recruited postnatally before 24 h of life. Newborn LTL was collected via heelstick at birth and maternal LTL was collected postnatally. LTL was determined by quantitative PCR. Using a longitudinal design, we evaluated associations between neonatal and maternal LTL and appropriate maternal gestational gain as indicated by the American College of Obstetrics and Gynecology (ACOG).

RESULT

Mean infant LTL was 2.02 ± 0.30 T/S (n = 386) and maternal LTL was 1.54 ± 0.26 T/S (n = 58). Independent risk factors for shorter LTL at birth included longer gestational duration (Coeff:-0.03, 95%CI: -0.05-0.01;p < 0.01) and maternal gestational weight gain below ACOG recommendations (Coeff:-0.10, 95%CI: -0.18 - -0.02; p = 0.01).

CONCLUSION

Gestational weight gain below ACOG recommendations may adversely impact neonatal health in Latinx infants as indicated by shorter LTL at birth.

The interaction of socioeconomic stress and race on telomere length in children: A systematic review and meta-analysis

Rationale

Proposed mechanisms relating early life exposures to poor health suggest that biologic indicators of risk are observable in childhood. Telomere length (TL) is a biomarker of aging, psychosocial stress, and a range of environmental exposures. In adults, exposure to early life adversity, including low socioeconomic status (SES), is predictive of shorter TL. However, results in pediatric populations have been mixed. Defining the true relation between TL and SES in childhood is expected to enhance the understanding of the biological pathways through which socioeconomic factors influence health across the life span.

Objective

The aim of this meta-analysis was to systematically review and quantitatively assess the published literature to better understand how SES, race, and TL are related in pediatric populations.

Methods

Studies in the United States in any pediatric population with any measure of SES were included and identified through the following electronic databases: PubMed, EMBASE, Web of Science, Medline, Socindex, CINAHL, and Psychinfo. Analysis utilized a multi-level random-effects meta-analysis accounting for multiple effect sizes within a study.

Results

Thirty-two studies were included with a total of 78 effect sizes that were categorized into income-based, education-based, and composite indicators. Only three studies directly tested the relation between SES and TL as the primary study aim. In the full model, there was a significant relation between SES and TL (r = 0.0220 p = 0.0286). Analysis by type of SES categorization identified a significant moderating effect of income on TL (r = 0.0480, 95% CI: 0.0155 to 0.0802, p = 0.0045) but no significant effect for education or composite SES.

Conclusions

There is an overall association between SES and TL that is predominately due to the association with income-based SES measures implicating income disparities as a key target for efforts to address health inequity across the life span. Identification of associations between family income and biological changes in children that predict life-span health risk provides key data to support public health policies addressing economic inequality in families and presents a unique opportunity to assess the effect of prevention efforts at the biologic level.

Demographic and health predictors of telomere length during adolescence

Telomere length (TL) is proposed to play a mechanistic role in how the exposome affects health outcomes. Little is known about TL during adolescence, a developmental period during which precursors of adult-onset health problems often emerge. We examined health and demographic sources of variation in TL in 899 youth aged 11-17. Demographic and health information included age, sex, race, household income, caregiver age and marital status, youth tobacco exposure, body mass index, pubertal status, health problems, medication use, and season of data collection. Genomic DNA was extracted from saliva, and T/S ratios were computed following qPCR. Age, race, season of data collection, and household income were associated with the telomere to single copy (T/S) ratio. We found that T/S ratios were larger at younger ages, among Black youth, for saliva collected during autumn and winter, and among households with higher income. Analyses stratified by race revealed that the association between age and T/S ratio was present for Black youth, that season of collection was present across races, but that family demographic associations with T/S ratio varied by race. The results provide information for future telomere research and highlight adolescence as a potentially important developmental phase for racial disparities in telomere shortening and health.

Association of Newborn Telomere Length With Blood Pressure in Childhood

IMPORTANCE

Adult telomere length (TL) is a biological marker of aging associated with vascular health. TL at birth is associated with later life TL and may contain early biological information of later life cardiovascular health and disease.

OBJECTIVE

To evaluate whether newborn TL is associated with early life blood pressure differences in childhood.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was part of the ENVIRONAGE (Environmental Influence on Aging in Early Life) study, a birth cohort of Belgian mother-child pairs with recruitment at birth and a median follow-up of 4.5 years conducted between October 2014 and July 2021. Participants included for analysis provided full data for evaluation at follow-up visit. Data analysis was conducted between August and September 2021.

MAIN OUTCOMES AND MEASURES

Cord blood and placental average relative TL were measured at birth using quantitative polymerase chain reaction (qPCR). Systolic, diastolic, and mean arterial pressure (MAP) were evaluated at follow-up. High childhood blood pressure (standardized for child age, sex, and height) was defined following the 2017 American Academy of Pediatrics guidelines. Multivariable adjusted linear and logistic regression models were used to associate newborn TL and blood pressure indicators in childhood.

RESULTS

This study included 485 newborn children (52.8% girls) with a mean (SD) age of 4.6 (0.4) years at the follow-up visit. Newborn TL was associated with lower blood pressure in childhood. A 1-IQR increase in cord blood TL was associated with a -1.54 mm Hg (95% CI, -2.36 to -0.72 mm Hg) lower diastolic blood pressure and -1.18 mm Hg (95% CI, -1.89 to -0.46 mm Hg) lower MAP. No association was observed with systolic blood pressure. Furthermore, a 1-IQR increase in cord blood TL was associated with lower odds of having high blood pressure at the age of 4 to 6 years (adjusted OR, 0.72; 95% CI, 0.53 to 0.98). In placenta, a 1-IQR increase in TL was associated with a -0.96 mm Hg (95% CI, -1.72 to -0.21 mm Hg) lower diastolic, -0.88 mm Hg (95% CI, -1.54 to -0.22 mm Hg) lower MAP, and a lower adjusted OR of 0.69 (95% CI, 0.52 to 0.92) for having a high blood pressure in childhood.

CONCLUSIONS AND RELEVANCE

In this prospective birth cohort study, variation in early life blood pressure at school-age was associated with TL at birth. Cardiovascular health may to some extent be programmed at birth, and these results suggest that TL entails a biological mechanism in this programming.

Race Differences in Telomere Length in Benign Prostate Biopsies and Subsequent Risk of Prostate Cancer

BACKGROUND

Telomere shortening is linked to aging and may be associated with increased risk for cancer. Most cancer studies have used telomere length in leukocytes rather than in the target tissue of cancer origin.

METHODS

A case-control study of 524 case-control pairs with a benign prostate biopsy nested within a historical cohort of 10,478 men was conducted to determine whether premalignant prostate telomere length (assessed using a modified qRT-PCR) is associated with prostate cancer risk.

RESULTS

Telomere lengths in benign prostate biopsies of cases versus controls were similar (1.46 ± 0.38 vs. 1.45 ± 0.42; P = 0.49). African American (AA) men had significantly shorter telomeres compared with White men (1.51 ± 0.38 vs. 1.63 ± 0.39; P < 0.0001). In race-stratified analyses, increasing telomere length was more strongly associated with prostate cancer risk in White men, wherein those with telomere length in the highest quartile had 1.9-fold greater adjusted risk of prostate cancer compared with men with prostate telomere lengths in the lowest quartile [OR = 1.90; 95% confidence interval (CI) = 1.08-3.36]. Men in the highest telomere length quartile also had a greater risk of aggressive prostate cancer compared with men with telomere lengths in the lowest quartile (OR = 2.78; 95% CI = 1.25-6.19).

CONCLUSIONS

White men have longer telomeres in benign prostate tissue compared with AA men, and those with the longest telomeres may be at increased risk for prostate cancer, particularly the more aggressive form of the disease.

IMPACT

Race-specific telomere length measures may be an early biomarker of aggressive prostate cancer.

Prenatal exposure to maternal psychological distress and telomere length in childhood

Telomere length (TL) is a biological marker of cellular aging, and shorter TL in adulthood is associated with increased morbidity and mortality risk. It is likely that these differences in TL are established long before adulthood, and there is growing evidence that TL can reflect prenatal experiences. Although maternal prenatal distress predicts newborn TL, it is unknown whether the relation between prenatal exposure to maternal distress and child TL persists through childhood. The purpose of the current longitudinal, prospective study is to examine the relation between prenatal exposure to maternal distress (perceived stress, depressive symptoms, pregnancy-related anxiety) and TL in childhood. Participants included 102 children (54 girls) and their mothers. Mothers' distress was assessed five times during pregnancy, at 12 weeks postpartum, and at the time of child telomere measurement between 6 and 16 years of age. Maternal distress during pregnancy predicted shorter offspring TL in childhood, even after accounting for postnatal exposure to maternal distress and other covariates. These findings indicate that maternal mental health predicts offspring TL biology later in childhood than previously observed. This study bolsters claims that telomere biology is subject to fetal programming and highlights the importance of supporting maternal mental health during pregnancy.

Influence of Maternal Infection and Pregnancy Complications on Cord Blood Telomere Length

Background

Exposure to suboptimal intrauterine environment might induce structural and functional changes that can affect neonatal health. Telomere length as an important indicator of cellular health has been associated with increased risk for disease development.

Objectives

This study was aimed to examine the independent and combined effects of maternal, obstetric, and foetal factors on cord blood telomere length (TL).

Methods

Pregnant women at the gestational age of 20^th to 24^th week who attended the antenatal clinic of a major local hospital in Hong Kong were recruited. Participants were asked to complete a questionnaire on demographics, health-related quality of life, and history of risk behaviors. Medical history including pregnancy complications and neonatal outcomes was obtained from electronic medical records of both mother and neonate. Umbilical cord blood was collected at delivery for TL determination.

Results

A total of 753 pregnant women (average age: 32.18 ± 4.51 years) were recruited. The prevalence of maternal infection, anaemia, and hypertension during pregnancy was 30.8%, 30.0%, and 6.0%, respectively. The adjusted regression model displayed that maternal infection was negatively associated with cord blood TL (β = -0.18, p = 0.026). This association became even stronger in the presence of antenatal anaemia, hypertension, delivery complications, or neonatal jaundice (β = -0.25 to -0.45).

Conclusions

This study consolidates evidence on the impact of adverse intrauterine environment at the cellular level. Maternal infection was significantly associated with shorter cord blood TL in a unique manner such that its presence may critically determine the susceptibility of telomere to other factors.

Longitudinal Follow-Up of Blood Telomere Length in HIV-Exposed Uninfected Children Having Received One Year of Lopinavir/Ritonavir or Lamivudine as Prophylaxis

Telomere shortening can be enhanced upon human immunodeficiency virus (HIV) infection and by antiretroviral (ARV) exposures. The aim of this study was to evaluate the acute and long-term effect on telomere shortening of two ARV prophylaxes, lopinavir/ritonavir (LPV/r) and lamivudine (3TC), administered to children who are HIV-exposed uninfected (CHEU) to prevent HIV acquisition through breastfeeding during the first year of life, and to investigate the relationship between telomere shortening and health outcomes at six years of age. We included 198 CHEU and measured telomere length at seven days of life, at week-50 and at six years (year-6) using quantitative polymerase chain reaction. At week-50, telomere shortening was observed among 44.3% of CHEU, irrespective of the prophylactic treatment. Furthermore, this telomere shortening was neither associated with poor growth indicators nor neuropsychological outcomes at year-6, except for motor abilities (MABC test n = 127, β = -3.61, 95%CI: -7.08, -0.14; p = 0.04). Safety data on telomere shortening for infant HIV prophylaxis are scarce. Its association with reduced motor abilities deserves further attention among CHEU but also HIV-infected children receiving ARV treatment.

Family socioeconomic status and child telomere length among the Samburu of Kenya

Previous research in high-income countries suggests that children from families with lower socioeconomic status (SES) tend to have shorter telomere length - a biomarker of stress and cell aging - than children from families with greater social and economic resources. However, little is known about predictors of child telomere length in low-income settings. Data for the current study are from a sample of 214 Samburu children aged 1-9 years. The Samburu are semi-nomadic pastoralists who live in the Rift Valley of north-central Kenya. Samburu livelihood is based primarily on livestock, and polygynous marriage is common. Drawing on prior ethnographic research, we measured 14 culturally relevant indicators of family SES, including mother's education, head of household's education, whether the child is currently attending school, household spending, mother's employment history, head of household's employment history, mother's perceived wealth, whether the child lives in a modern house, livestock holdings (total, cows, sheep/goats, and camels), mother's wife number, and whether the child lives in a polygynous household. Telomere length was measured in salivary DNA by the quantitative polymerase chain reaction (qPCR) method. Using latent class analysis, we identified four groups of children that are similar based on the 14 indicators of family SES: Lower SES; Middle SES, Traditional; Middle SES, Modern; and Higher SES. SES classes were not significantly associated with child telomere length. In models examining individual indicators of SES, we found that telomere length was 0.57 standard deviations greater for children who lived in families in the lowest quartile of total livestock holdings compared to those in the highest quartile (b = 0.57, p = 0.03). While additional research is needed to identify the mechanisms underlying this counterintuitive finding, the current study highlights the importance of cultural context in shaping the social gradient in health.

Obesity at Age 6 Months Is Associated with Shorter Preschool Leukocyte Telomere Length Independent of Parental Telomere Length

OBJECTIVE

To assess whether early modifiable dietary factors and obesity measures are associated with leukocyte telomere length at 3-5 years of age after controlling for the heritability of leukocyte telomere length in a prospective cohort of low-income Latina mothers and their children in San Francisco.

STUDY DESIGN

We analyzed data from the Latinx, Eating and Diabetes cohort, a prospective study of 97 woman-infant dyads. We used linear regression models to evaluate associations between early dietary factors and obesity measures and child leukocyte telomere length at 3-5 years of age. Multivariable models included child age at the time of telomere collection, breastfeeding at 6 months (yes/no), obesity at 6 months, maternal education, child sex, and maternal and paternal leukocyte telomere length.

RESULTS

Data for 73 of the 97 children at 3-5 years of age were analyzed. Any breastfeeding at 6 months was positively associated (β = 0.14; P = .02) and obesity at 6 months was negatively associated (β = -0.21; P < .001) with leukocyte telomere length in bivariate analyses. In multivariable models including parental leukocyte telomere length, obesity at 6 months was associated with a shorter leukocyte telomere length at 3-5 years of age (β = -0.15; P = .02). Analyses of dietary factors showed high flavored milk consumption at 3 years of age was associated with shorter leukocyte telomere length after adjustment for possible confounders.

CONCLUSIONS

In a low-income Latinx population, obesity at 6 months of age is negatively associated with cellular health at 3-5 years of age after controlling for genetic factors (parental leukocyte telomere length) associated with leukocyte telomere length. Early life obesity may be more deleterious for cellular health than obesity later in childhood.

Telomere length determinants in childhood

Telomere length (TL) is a dynamic marker that reflects genetic predispositions together with the environmental conditions of an individual. It is closely related to longevity and a number of pathological conditions. Even though the extent of telomere research in children is limited compared to that of adults, there have been a substantial number of studies providing first insights into child telomere biology and determinants. Recent discoveries revealed evidence that TL is, to a great extent, determined already in childhood and that environmental conditions in adulthood have less impact than first believed. Studies have demonstrated that large inter-individual differences in TL are present among newborns and are determined by diverse factors that influence intrauterine development. The first years of child growth are associated with high cellular turnover, which results in fast shortening of telomeres. The rate of telomere loss becomes stable in early adulthood. In this review article we summarise the existing knowledge on telomere dynamics during the first years of childhood, highlighting the conditions that affect newborn TL. We also warn about the knowledge gaps that should be filled to fully understand the regulation of telomeres, in order to implement them as biomarkers for use in diagnostics or treatment.

Social inequalities in accelerated aging among southern U.S. women: an analysis of the biosocial and behavioral pathways linking social determinants to telomere length

Few studies have examined the biosocial pathways linking socioeconomic status (SES) to accelerated aging in a population-based sample of southern US women. Even fewer have examined the importance of chronic compared to perceived stress in linking SES to women's salivary telomere length (STL). Using data from a probability-based sample of 156 US women and structural equation modeling, we examined three pathways - chronic stress exposure, stress appraisal, and coping behavior - linking SES to STL. SES was positively associated with STL (β_TE = 0.16, p < .05). Everyday discrimination was negatively associated with STL (β_DE = -0.21, p < .05), but perceived stress was positively associated with STL (β_DE = 0.20, p < .05). Current smoking decreased STL (β_DE = -0.19, p < .01). Perceived stress acted to suppress the negative relationship of chronic stress exposure on STL. Given the dearth of STL studies that include measures of both perceived and chronic stress, our study supports the importance of disentangling stress measures and a biosocial approach to the study of accelerated aging.

Newborn telomere length predicts later life telomere length: Tracking telomere length from birth to child- and adulthood

Background

Telomere length (TL) is considered a biological marker of aging and may indicate age-related disease susceptibility. Adults and children show a fixed ranking and tracking of TL over time. However, the contribution of an individual's initial birth TL to their later life TL is unknown. We evaluated change and tracking of TL from birth to child- and adulthood.

Methods

Telomere length at birth was measured using qPCR in two independent prospective birth cohorts. After a median follow-up period of 4 years in ENVIRONAGE (n = 273) we assessed leukocyte telomere length (LTL) and after 23 years in EFPTS (n = 164) buccal TL was assessed. Correlations and multivariable regression models were applied to study telomere tracking and determinants of TL change from birth onwards.

Findings

In children, LTL at the age of 4 correlates with TL at the start of life both in cord blood (r = 0.71, P < 0.0001;) and placenta (r = 0.60, P < 0.0001) and was –11.2% and –33.1% shorter, respectively. In adulthood, buccal TL at the age of 23 correlates with placental TL (r = 0.46, P < 0.0001) and was –35.9% shorter. TL attrition was higher in individuals with longer birth TL. However, based on TL ranking, individuals do not tend to change dramatically from TL rank after 4 or 23 years of follow-up. Finally, longer maternal TL associates with lower telomere attrition in the next generation.

Interpretation

The high prediction of newborn TL for later life TL, and stable TL ranking from birth onwards underscores the importance of understanding the initial setting of newborn TL and its significance for later life.

Funding

European Research Council (ERC-StG310898) and Flemish Scientific Fund (12X9620N).

Maternal psychosocial functioning, obstetric health history, and newborn telomere length

There is growing interest in elucidating the determinants of newborn telomere length, given its potential as a biomarker of lifetime disease risk affected by prenatal exposures. There is limited evidence that increased maternal stress during pregnancy predicts shorter newborn telomere length. However, the few studies published to date have been conducted primarily with small samples utilizing inconsistent definitions of maternal stress. Moreover, the potential influence of fetal sex as a moderator of maternal stress effects on newborn telomere length has been largely ignored despite compelling evidence of likely impact. In a prospective cohort study of pregnant women seeking routine prenatal care, we tested whether a range of maternal measures of stressor exposures, subjective feelings of stress, and mental health (depression, anxiety) were associated with newborn telomere length assessed from cord blood among 146 pregnant women and their newborn infants. We further examined whether the pattern of associations differed by infant sex. Sociodemographic and maternal and newborn health indicators were considered as potential covariates. When examined within the whole sample, none of the maternal psychosocial measures were associated with newborn telomere length. Among potential covariates, maternal history of smoking and preeclampsia in a previous pregnancy were negatively associated with newborn telomere length. In adjusted linear regression analyses that considered potential sex-specific effects, maternal depression, general anxiety, and pregnancy-specific anxiety symptoms were positively associated with newborn telomere length among males. Overall, the findings provide some evidence for an association between maternal psychosocial wellbeing in pregnancy and newborn telomere length in males, although in the opposite direction than previously reported. Maternal smoking and obstetric history prior to conception may be associated with shorter offspring telomere length.

Maternal stress or sleep during pregnancy are not reflected on telomere length of newborns

Telomeres play an important role in maintaining chromosomal integrity. With each cell division, telomeres are shortened and leukocyte telomere length (LTL) has therefore been considered a marker for biological age. LTL is associated with various lifetime stressors and health-related outcomes. Transgenerational effects have been implicated in newborns, with maternal stress, depression, and anxiety predicting shorter telomere length at birth, possibly reflecting the intrauterine growth environment. Previous studies, with relatively small sample sizes, have reported an effect of maternal stress, BMI, and depression during pregnancy on the LTL of newborns. Here, we attempted to replicate previous findings on prenatal stress and newborn LTL in a sample of 1405 infants using a qPCR-based method. In addition, previous research has been expanded by studying the relationship between maternal sleep quality and LTL. Maternal prenatal stress, anxiety, depression, BMI, and self-reported sleep quality were evaluated with self-reported questionnaires. Despite sufficient power to detect similar or even considerably smaller effects than those previously reported in the literature, we were unable to replicate the previous correlation between maternal stress, anxiety, depression, or sleep with LTL. We discuss several possible reasons for the discrepancies between our findings and those previously described.

The limited use of US residual newborn screening dried bloodspots for health disparity research

PURPOSE

State-run newborn screening programs screen nearly all babies born in the United States at the time of delivery. After newborn screening has been completed, some states store the residual dried bloodspots. It is unknown how they have been used to address health disparities-related research.

METHODS

In 2017-2018, a scoping review was conducted to evaluate the extent, type, and nature of how residual dried bloodspots. The review included 654 eligible publications, worldwide, published before May 2017. A post hoc analysis of the US-based studies using residual dried bloodspots (n = 192) were analyzed.

RESULTS

There were 32 (16.7%) articles identified that studied a condition of a known health disparity or focused on a key population: 25 studies assessed a disease or condition, 6 expressly enrolled a key population, and 1 study included both (i.e., heart disease and African American/Black).

CONCLUSION

Excluding 12 studies that researched leukemia or a brain tumor, only 20 studies addressed a known health disparity, with 6 stating a specific aim to address a health disparity. This resource could be used to gain further knowledge about health disparities, but is currently underutilized.

Social Relationships and Salivary Telomere Length Among Middle-Aged and Older African American and White Adults

OBJECTIVES

A common mechanism underlying premature morbidity may be accelerated biological aging as reflected by salivary telomere length (STL). This study examined the extent to which social relationships, both positive and negative, can be protective or confer risk relative to biological aging.

METHOD

Data from the Health and Retirement Study and multiple regression were used to examine cross-sectional associations between STL, self-reported social support, and negative interaction (e.g., conflict, criticism) with family in a nationally representative sample of African American and non-Hispanic White middle-aged and older adults (N = 4,080).

RESULTS

Social support from family was associated with shorter STL. Negative interaction with family had no main effect on STL but interactions characterized by high social support and more frequent negative interactions were associated with longer STL. Negative interaction with family was negatively associated with STL for African Americans and Whites but the magnitude of the effect was greater for African Americans.

DISCUSSION

Study findings highlight the role of social relationships in physiological deterioration among middle-aged and older adults and identify a potential mechanism whereby race is linked to accelerated biological aging. Findings highlight the importance of considering positive and negative aspects of social relationships to understand the consequences of social connections for cellular aging in diverse populations.

Advances in Understanding the Causes and Consequences of Health Disparities in Aging Minorities

PURPOSE OF REVIEW

The purpose was to discuss appropriate methods for advancing our understanding of health disparities or minority aging including life-course perspectives, biological measures, pain measurement, and generational approaches.

RECENT FINDINGS

Life course perspectives provide an orientation for studying older minorities that concomitantly captures exposures and stressors that may lead to earlier onset of disease and premature mortality. The use of biological markers to study health disparities in older minorities is necessary in order to identify pathways between psychosocial factors and health outcomes. Work focusing on pain disparities should include explorations of relationships between psychosocial factors, and subjective and objective measures of pain. Studying families can provide insight into genetic associations and coping styles in older minorities.

SUMMARY

Methodological approaches that take life course, biology, and social factors into account may help identify causal pathways between social determinants of health and health outcomes among older minorities. Once these causal pathways have been identified, more strategies and interventions that strive toward health equity across older adults of all race/ethnic groups can be developed.

Association of Parental Socioeconomic Status and Newborn Telomere Length

IMPORTANCE

Low socioeconomic status is associated with higher all-cause mortality and risks for aging-related diseases. Biological aging is a potential process underlying health conditions related to social disadvantages, which may be present from birth onward.

OBJECTIVE

To evaluate the association of parental socioeconomic status with telomere length (TL) at birth, a marker of biological aging.

DESIGN, SETTING, AND PARTICIPANTS

This prospective birth cohort study was conducted among 1504 mother-newborn pairs in Belgium recruited between February 1, 2010, and July 1, 2017.

EXPOSURES

Parental socioeconomic measures, including maternal educational level, occupation, paternal educational level, and neighborhood income based on median annual household income.

MAIN OUTCOMES AND MEASURES

Mean relative TL was measured in cord blood and placental tissue. By constructing a principal component, an integrative socioeconomic measure was derived that integrates parental socioeconomic status and neighborhood income. Multivariable adjusted regression analyses were performed to associate the integrative socioeconomic measure and TL at birth.

RESULTS

In 1026 newborns (517 boys; mean [SD] gestational age, 39.2 [1.4] weeks), a higher socioeconomic status was associated with longer cord blood TL and placental TL. Each unit increment in the integrative socioeconomic status measure was associated with 2.1% (95% CI, 0.9%-3.4%; P < .001) longer cord blood TL in boys, while no association was observed for girls (0.5% longer cord blood TL; 95% CI, -0.9% to 1.8%; P = .50). The sex-specific socioeconomic status interaction revealed a stronger association in boys compared with newborn girls (1.6%; 95% CI, 0.02%-3.3%; P = .047 for interaction). In placental tissue, higher socioeconomic status was associated with 1.8% (95% CI, 0.3%-3.3%; P = .02) longer TL in newborn boys but not in girls (0.4% longer TL; 95% CI, -1.2% to 2.0%; P = .63). For placental tissue, no sex and socioeconomic status interaction on TL was observed (1.4%; 95% CI, -0.5% to 3.4%; P = .16 for interaction).

CONCLUSIONS AND RELEVANCE

This study suggests that parental socioeconomic status is associated with newborn TL, especially in boys. The results indicate that familial social economic factors are associated with the potential cellular longevity of the next generation, with a potential higher transgenerational vulnerability for newborn boys.

Patterns of change in telomere length over the first three years of life in healthy children

There is growing interest in the use of telomere length as a biomarker of health and a predictor of later morbidity and mortality. However, little is known about developmentally expected telomere erosion over the first years of life. This gap hinders our ability to interpret the meaning of relative telomere length and rate of attrition in relation to risk factors and health outcomes. The overall goal of this study was to examine the rate of relative telomere length attrition in a large, normative sample of healthy children (N = 630) followed from infancy to three years of age. A secondary goal was to explore associations between sociodemographic characteristics and telomere erosion over this time period. Relative telomere length was assessed from DNA in saliva samples collected in infancy (M = 8.6 months), age 2 years (M = 25.2 months), and age 3 years (M = 38.3 months). In the sample as a whole, relative telomere length decreased from infancy to 2 years but remained stable from 2 years to 3 years. Notably, increases in relative telomere length were observed in 29 % of children between infancy and 2 years of age and in 46 % of children between 2 and 3 years of age; 62 % of children showed both increases and decreases in relative telomere length across the study period. Females showed longer relative telomere length than males, regardless of timepoint. There was some evidence that parental age and family finances were associated with changes in child relative telomere length across time. Overall, the findings suggest that telomere length attrition is not uniform across the early years of life, with the most rapid attrition occurring during the first two years, and that increases as well as decreases in telomere length during this period are commonly observed.

Association of sleep quality with telomere length, a marker of cellular aging: A retrospective cohort study of older adults in the United States

BACKGROUND

Sleep quality is a risk factor for age-related diseases, and although the underlying mechanisms remain unclear, the effects of poor sleep quality on telomere length (TL) may play a role.

OBJECTIVE

The objective of the study was to evaluate the independent association between sleep quality and salivary TL in a large sample of older adults.

DESIGN

We adopted a retrospective cohort design, and participants comprised 5,268 adults drawn from the Health and Retirement Study. We used the 2006 (baseline) and 2008 (follow-up) waves. Baseline sleep quality was assessed using 4 Likert scale questions (trouble falling asleep, waking up during the night, waking up too early and not being able to fall sleep again, and feeling well rested in the morning). The TL was assessed using the T/S ratio, a continuous variable. The associations between sleep quality and T/S were assessed using multivariable ordinary least squares regressions. All analyses were adjusted for demographics, lifestyle characteristics, psychosocial, and other factors.

RESULTS

Overall, 16% reported never feeling well rested in the morning; 25.7% of respondents always had trouble waking during the night; and 12.8% always had trouble waking up too early in the morning. Respondents who never felt rested in the morning had significantly shorter TL than those who always felt rested in the morning (adjusted beta = -0.08, standard error = 0.03, P < .01). The composite sleep measure was not significantly associated with shorter TL.

CONCLUSIONS

In this cohort of older adults, not feeling well rested in the morning was significantly and inversely associated with TL; however, the composite measure of sleep quality was not significantly associated with TL. These findings suggest a potential connection between one of the measures of impaired sleep and reduction in TL, a marker of cellular aging that has been linked to multiple chronic conditions.

Maternal Caffeine Consumption and Racial Disparities in Fetal Telomere Length

BACKGROUND AND OBJECTIVES

The identification of risk factors for shorter telomere length, especially during fetal development, would be important towards caffeine consumption recommendations for pregnant women on a global scale. The purpose of this study was to evaluate the association between caffeine intake and fetal telomere length as well as racial/ethnic differences in telomere length regardless of maternal caffeine consumption status.

METHODS

Caffeine intake was measured using a food frequency questionnaire (FFQ). Three generalized linear models (GLM) were compared based on binary categorical variables of caffeine levels using data mean value of 117.3 mg as cut-off; the World Health Organization (WHO) recommendations of 300 mg; and the American College of Obstetricians and Gynecologists (ACOG) recommendations of 200 mg. The association between caffeine consumption and telomere length (telomere to single-copy [T/S] ratio) was then assessed.

RESULTS

Among 57 maternal-fetal dyads, 77.2% reported less than 200 mg of caffeine (ACOG) and 89.5% less than 300 mg (WHO). Both WHO and ACOG models found that caffeine intake was significantly and positively associated with longer telomere length (p<0.05); and sodium (p<0.05). Other" race (p<0.001) and "white" race (p<0.001) were also significantly and positively associated with longer telomere length in the same models. Increasing maternal age shortened telomere length significantly in all models (p<0.001).

CONCLUSION AND GLOBAL HEALTH IMPLICATIONS

Caffeine intake, maternal age, and race may be associated with alterations in fetal telomere length. This indicates that caffeine consumption during pregnancy may have long-term implications for fetal development. The racial/ethnic differences in telomere length found in this study warrant larger studies to further confirm these associations.

Do black/white differences in telomere length depend on socioeconomic status?

Social and economic disadvantage are hypothesized to increase the risk of disease and death via accelerated biological aging. Given that US blacks are socially and economically disadvantaged relative to whites, health disparities scholars expected that blacks would have shorter telomere length-a biomarker of cell aging-than whites. Yet the majority of studies have found that blacks have longer telomere length than whites. Using data from the National Health and Nutrition Examination Survey (n = 3,761; 28.3% non-Hispanic black, 71.7% non-Hispanic white), we found that leukocyte telomere length was 4.00% (95% CI: 1.12%, 6.87%) longer among blacks compared to whites in the full sample, but differences were greatest among those with lower SES (5.66%; 95% CI: 0.10%, 10.32%), intermediate among those with middle SES (4.14%; 95% CI: 0.05%, 8.24%), and smallest among those with higher SES (2.33%; 95% CI: -3.02%, 7.67%). These results challenge purely genetic explanations for race differences in telomere length and point to a potential social-environmental cause of longer telomere length in US blacks.

Childhood maltreatment, behavioral adjustment, and molecular markers of cellular aging in preschool-aged children: A cohort study

OBJECTIVE

Childhood maltreatment is a major risk factor for the development of behavioral problems and poor physical and mental health. Accelerated cellular aging, through reduced telomere length and mitochondrial dysfunction, may be a mechanism underlying these associations.

METHODS

Families with (n = 133) and without (n = 123) child welfare documentation of moderate-severe maltreatment in the past six months participated in this study. Children ranged in age from 3 to 5 years, were racially and ethnically diverse, and 91% qualified for public assistance. Structured record review and interviews were used to assess a history of maltreatment and other adversities. Telomere length and mitochondrial DNA copy number (mtDNAcn) were measured from saliva DNA using real-time PCR. Measures were repeated at a six-month follow-up assessment. Repeated measures general linear models were used to examine the effects of maltreatment and other adversities on telomere length and mtDNAcn over time.

RESULTS

Maltreatment and other adverse experiences were significant positive predictors of both telomere length and mtDNAcn over time. Internalizing and externalizing behavior problems were also both significantly associated with telomere length, but only internalizing symptoms were associated with mtDNAcn.

CONCLUSIONS

This is the first study to show that mtDNAcn is altered in children with stress and trauma, and the findings are consistent with recent studies of adults. Surprisingly, children who experienced moderate-severe levels of maltreatment in the prior six months had longer telomeres, possibly reflecting compensatory changes in response to recent trauma. Telomere length and mtDNAcn were also associated with behavioral problems, suggesting that these measures of cellular aging may be causally implicated in the pathophysiology of stress-related conditions.

Maternal cortisol output in pregnancy and newborn telomere length: Evidence for sex-specific effects

Newborn telomere length is a potential biomarker of the effects of maternal-fetal processes on offspring long-term health. A number of maternal psychosocial and environmental factors in pregnancy (e.g., stress, health, socioeconomic status) have been associated with shortened telomere length at birth. The physiological mechanisms responsible for potential effects of maternal factors on newborn telomere length have yet to be identified. Indirect evidence suggests that disruptions in maternal hypothalamic-pituitary-adrenal (HPA) axis functioning in pregnancy may be involved. Studies are needed that test whether maternal HPA axis functioning in pregnancy is associated with newborn telomere length. This study examined whether maternal HPA axis functioning across pregnancy, reflected in hair cortisol collected within one week after delivery, predicted newborn telomere length assessed from leukocyte cord blood collected at birth among 93 sociodemographically diverse mother-infant dyads. We further tested whether associations between maternal hair cortisol and newborn telomere length differed by infant sex, given documented sex differences in prenatal environmental exposure effects on offspring health, patterns of cortisol exposure during gestation, and telomere biology across the lifespan. In a multi-group structural equation modeling analysis that accounted for cortisol exposures across trimesters, maternal cortisol levels in pregnancy were not associated with newborn telomere length in the sample as a whole. However, significant sex differences emerged, with a significant positive association among females and a lack of a significant association among males. In addition, analyses revealed that cortisol levels were higher across trimesters among mothers of male infants than mothers of female infants. The results suggest that functioning of the maternal HPA axis in pregnancy may differ by fetal sex and have sex-specific effects on newborn telomere biology. These findings have implications for understanding the mechanisms by which maternal psychosocial and environmental exposures influence newborn telomere length and for elucidating mechanisms contributing to sex disparities in health.

Parity associated with telomere length among US reproductive age women

STUDY QUESTION

Is telomere length related to parity among a nationally representative sample of US reproductive age women?

SUMMARY ANSWER

History of live birth was associated with shorter telomere length.

WHAT IS KNOWN ALREADY

Shorter telomeres have been linked with a range of chronic health conditions and mortality and parity has been associated with health indicators. However, there is a lack of research on how parity relates to telomere length.

STUDY DESIGN, SIZE, DURATION

This nationally representative, cross-sectional study included 1954 women from the National Health and Nutrition Examination Survey, 1999-2002, the only survey period which includes measurement of telomere length.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women aged 20-44 were included. Parity, defined as number of previous live births, was ascertained by questionnaire. Leukocyte telomere length was measured by polymerase chain reaction and reported as a ratio in relation to standard reference DNA (T/S ratio). The relationship between leukocyte T/S ratio and parity was examined using survey weighted linear regression. Models were adjusted for race/ethnicity, age, BMI, income-to-poverty ratio, education, early age at menarche and smoking status.

MAIN RESULTS AND THE ROLE OF CHANCE

Among reproductive age women in the US, the adjusted mean leukocyte T/S ratio was 4.2% (95% CI: 0.9, 7.3) shorter in parous compared with nulliparous women. Parity was associated with 116 fewer base pairs (95% CI: 26, 204) on average, using estimated coefficients from the adjusted linear regression models and mean covariate values.

LIMITATIONS REASONS FOR CAUTION

This study was cross-sectional and therefore was unable to establish temporality. The dataset lacked information on social factors, stress and fertility status, which may help explain these findings. Only two previous studies have examined this question and our findings should be interpreted with caution.

WIDER IMPLICATIONS OF THE FINDINGS

These findings in a nationally representative sample of US reproductive age women suggest that history of live birth may be associated with accelerated cellular aging. The magnitude of the observed association was greater than that of the impact of smoking or obesity on telomere length, suggesting that parity may have an independent influence on cellular aging and warrant further study.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded in part by the Undergraduate Research Scholars Program at George Mason University. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

NA.

A scoping systematic review of social stressors and various measures of telomere length across the life course

Numerous studies examine the relationship between social stressors and telomere length (TL). Beyond considering methods and major findings, this scoping systematic review takes a novel approach as it groups studies according to the types of social stressor considered and by age groups. Following PRISMA guidelines, we searched PubMed, Web of Science, Embase, and Scopus. We included all English-language human subject research articles that modeled any measure of TL as a dependent variable and exposure to a social stressor as an independent variable. For the sample of 105 articles, we summarized methods and findings by type of social stressor (socioeconomic stressors, stressful life events, work-related stressors, and neighborhood stressors) and by age of the study population (infants/children, middle-aged adults, older adults, and mixed samples of middle-aged and older adults). We found more variation in TL measurement methodology in studies of infants/children and older adults than in studies focusing on middle-aged adults. The most consistent finding was a relationship between early-life stressors and shorter TL. Work and neighborhood stressors, and older populations, are currently understudied. Across all stressors, limited evidence suggests that the stress-TL relationship may be moderated by characteristics such as age, sex, and race/ethnicity. We conclude with specific suggestions for future research.

Genetic Determinants of Telomere Length in African American Youth

Telomere length (TL) is associated with numerous disease states and is affected by genetic and environmental factors. However, TL has been mostly studied in adult populations of European or Asian ancestry. These studies have identified 34 TL-associated genetic variants recently used as genetic proxies for TL. The generalizability of these associations to pediatric populations and racially diverse populations, specifically of African ancestry, remains unclear. Furthermore, six novel variants associated with TL in a population of European children have been identified but not validated. We measured TL from whole blood samples of 492 healthy African American youth (children and adolescents between 8 and 20 years old) and performed the first genome-wide association study of TL in this population. We were unable to replicate neither the 34 reported genetic associations found in adults nor the six genetic associations found in European children. However, we discovered a novel genome-wide significant association between TL and rs1483898 on chromosome 14. Our results underscore the importance of examining genetic associations with TL in diverse pediatric populations such as African Americans.

Sex differences in effects of maternal risk and protective factors in childhood and pregnancy on newborn telomere length

Little research has examined determinants of newborn telomere length, a potential biomarker of lifetime disease risk impacted by prenatal exposures. No study has examined whether maternal exposures in childhood influence newborn telomere length or whether there are sex differences in the maternal factors that influence newborn telomere length. We tested whether a range of maternal risk and protective factors in childhood and pregnancy were associated with newborn telomere length among 151 sociodemographically diverse mother-infant dyads. We further examined whether the pattern of associations differed by infant sex. Newborn telomere length was assessed from cord blood collected at birth. Risk/protective factors included maternal health (smoking, body mass index), socioeconomic status (education, income), stress exposures, and mental health (depressive and posttraumatic stress disorder symptoms) in pregnancy as well as maternal experiences of abuse (physical, emotional, sexual) and familial emotional support in childhood. When examined within the whole sample, only maternal smoking in pregnancy and familial emotional support in childhood emerged as significant predictors of newborn telomere length. Male and female newborns differed in their pattern of associations between the predictors and telomere length. Among males, maternal smoking, higher body mass index, and elevated depressive symptoms in pregnancy and maternal sexual abuse in childhood were associated with shorter newborn telomere length; higher maternal educational attainment and household income in pregnancy and greater maternal familial emotional support in childhood were associated with longer newborn telomere length. Together, these factors accounted for 34% of the variance in male newborn telomere length. None of the risk/protective factors were associated with female newborn telomere length. The results suggest that male fetuses are particularly susceptible to maternal exposure effects on newborn telomere length. These findings have implications for elucidating mechanisms contributing to sex disparities in health.

Early life adiposity and telomere length across the life course: a systematic review and meta-analysis

Background: The relationship between adiposity at birth and in childhood, and telomere length is yet to be determined. We aimed to systematically review and meta-analyse the results of studies assessing associations between neonatal and later childhood adiposity, and telomere length. Methods: We searched Medline, EMBASE and PubMed for studies reporting associations between adiposity measured in the neonatal period or later childhood/adolescence, and leucocyte telomere length, measured at any age via quantitative polymerase chain reaction, or terminal restriction fragment analysis, either cross-sectionally, or longitudinally. Papers published before April 2017 were included. Results: Out of 230 abstracts assessed, 23 papers (32 estimates) were retained, from which 19 estimates were meta-analysed (15 cross-sectional, four longitudinal). Of the 15 cross-sectional estimates, seven reported on neonates: four used binary exposures of small-for-gestational-age vs. appropriate-for-gestational age (or appropriate- and large-for-gestational age), and three studied birth weight continuously. Eight estimates reported on later childhood or adolescent measures; five estimates were from studies of binary exposures (overweight/obese vs. non-obese children), and three studies used continuous measures of body mass index. All four longitudinal estimates were of neonatal adiposity, with two estimates for small-for-gestational-age vs. appropriate-for-gestational age neonates, and two estimates of birth weight studied continuously, in relation to adult telomere (49-61 years). There was no strong evidence of an association between neonatal or later childhood/adolescent adiposity, and telomere length. However, between study heterogeneity was high, and there were few combinable studies. Conclusions: Our systematic review and meta-analysis found no strong evidence of an association between neonatal or later childhood or adolescent adiposity and telomere length.

Telomere length was similar in school-age children with bronchopulmonary dysplasia and allergic asthma

AIM

Inflammation is a major factor in the pathophysiology of bronchopulmonary dysplasia (BPD), and it contributes to accelerated telomere shortening and cellular ageing. This study aimed to determine its effect on telomere length and lung function in school-aged children born preterm with BPD.

METHODS

We examined 29 children with BPD, born preterm in Stockholm county 1998-99, along with 28 children with allergic asthma born at term matched for age and gender. At 10 years of age, we measured relative telomere length (RTL) in blood by quantitative polymerase chain reaction, lung function by spirometry and inflammation by fractional exhaled nitric oxide and blood cytokines.

RESULTS

RTL was not different in preterm born with BPD compared to term born children with asthma. The gender effect was strong in both groups; girls had significantly longer median RTL than boys (1.8 versus 1.5, p < 0.01). Short RTL was associated with low forced expiratory flow, also after adjusting for gender, but was not affected by severity of BPD or ongoing inflammation.

CONCLUSION

Telomere length was similar in 10-year-old children born preterm with a history of BPD and term born children with allergic asthma. However, impaired lung function and male gender were associated with short telomeres.

Racial differences in maternal and umbilical cord blood leukocyte telomere length and their correlations

PURPOSE

Telomere length at birth sets the baseline for telomere shortening and may influence adult disease risk like cancer. Telomere length is heritable, but may also be a marker of exposures in utero, including those influencing racial differences in risk. We examined racial differences in telomere length in maternal and umbilical cord blood from male neonates, and maternal-neonate correlations to generate hypotheses.

METHODS

Black and white pregnant women were recruited in 2006-2007 and followed to postpartum. Data came from questionnaires and medical records. Relative telomere length was measured by qPCR in leukocyte DNA. We estimated mean telomere length in mothers and neonates (n = 55 pairs) using linear regression and maternal-cord blood Spearman correlations, overall and by race.

RESULTS

Black mothers had shorter age- and plate-adjusted telomere length (2.49, 95% CI 2.11-2.86) than whites (2.92, 95% CI 2.63-3.22; p = 0.1) and black neonates had shorter telomere length (2.58, 95% CI 2.16-3.01) than whites (3.13, 95% CI 2.79-3.47; p = 0.1), though not statistically significant. Differences were attenuated after further adjustment for maternal factors. Maternal-cord blood correlations were moderate (r = 0.53, p < 0.0001), and did not differ by race.

CONCLUSION

Telomere length may differ by race at birth due to both inherited and racial differences in maternal factors. This study was for hypothesis generation and results should be followed up in larger studies.

Income and Self-Rated Mental Health: Diminished Returns for High Income Black Americans

Background: The minorities' diminished return theory suggests that socioeconomic position (SEP) generates smaller health gains for racial/ethnic minorities compared to Whites. The current study was a Black⁻White comparison of the association between household income and self-rated mental health (SRMH). Methods: This cross-sectional study used data from the 2017 State of the State Survey (SOSS). With representative sampling, the SOSS generates results that are generalizable to the state of Michigan. This study included 881 adults, (n = 92) Black and (n = 782) White. The independent variable was household income. The dependent variable was SRMH, measured using a single item. Age, gender, and participation in the labor force were covariates. Race/ethnicity was the focal moderator. Logistic regression models were used for data analysis. Results: Overall, higher household income was associated with better SRMH, net of covariates. An interaction was found between race/ethnicity and household income on SRMH, suggesting a smaller, or nonexistent, protective effect for Blacks compared to Whites. In race/ethnicity-stratified models, higher household income was associated with better SRMH for Whites but not Blacks. Conclusion: Supporting the minorities' diminished return theory, our study documents differential effects for income on SRHM for Blacks and Whites, where Whites but not Blacks appear to benefit from their income. Given this, researchers and policy makers are cautioned against making assumptions that racial groups benefit equally from similar economic resources.

Leukocyte Telomere Length and Pancreatic Cancer Risk: Updated Epidemiologic Review

Many risk factors have been firmly established for pancreatic cancer (PC), but the molecular processes by which known risk factors influence susceptibility to PC are not clear. There has been a recent upsurge of interest in the role of telomere length (TL), the protective DNA sequence repeats at chromosome ends, in pancreatic carcinogenesis. Given this heightened interest, we performed an in-depth, focused, and up-to-date review of the epidemiological evidence linking leukocyte TL (LTL) with PC risk. We searched MEDLINE, Embase, and the Cochrane Library databases for all published studies on LTL and PC risk, up to May 2017. Five studies were identified for review: 4 nested case-control studies and 1 retrospective case-control study. Two studies found opposite associations between LTL and PC risk: 1 found a dose-response positive association and the other found a dose-response inverse association. Two studies also found a "U-shaped" association, whereas another reported a weak nonlinear relationship. We offer potential reasons for the conflicting findings including variation in study design, biospecimen characteristics, and differences in interlaboratory measurements of TL. Future studies should carefully control for risk factors of PC that are associated also with telomere attrition and investigate the role of genetic variation in TL maintenance.

Leukocyte Telomere Length at Birth and During the Early Life of Children Exposed to but Uninfected With HIV After In Utero Exposure to Antiretrovirals

Background

Maternal combination antiretroviral therapy (cART) during pregnancy could impact the health of human immunodeficiency virus (HIV)-exposed, HIV-uninfected (HEU) children, because some antiretrovirals cross the placenta and can inhibit telomerase. Our objective was to compare leukocyte telomere length (LTL) in HEU children and HIV-unexposed, HIV-uninfected (HUU) children at birth and in early life and to investigate any relationship with cART exposure.

Methods

HEU and HUU children's blood LTL was compared cross-sectionally at birth, and during the first three years of life. Longitudinal HEU LTL dynamics was evaluated over that same period.

Results

At birth, the LTL in HEU children (n = 114) was not shorter than that in HUU children (n = 86), but female infants had longer LTL than male infants. Maternal cART (duration or type) showed no association with shorter infant LTL. Among 214 HEU children age- and sex-matched at a 1:1 ratio to HUU children, LTL declined similarly in both groups. In a longitudinal analysis, LTL attrition in HEU children was rapid from birth to 1 year of age and gradual thereafter. Zidovudine prophylaxis did not significantly alter LTL.

Conclusions

Our results indicate that from birth to 3 years of age, the LTL in HEU children is not negatively affected by exposure to maternal HIV infection and cART, at least not to the regimens used within this Canadian cohort, a reassuring finding.

Early life adiposity and telomere length across the life course: a systematic review and meta-analysis

Background: The relationship between adiposity at birth and in childhood, and telomere length is yet to be determined. We aimed to systematically review and meta-analyse the results of studies assessing associations between neonatal and childhood adiposity, and telomere length. Methods: We searched Medline, EMBASE and PubMed for studies reporting associations between adiposity measured in the neonatal period or childhood, and leucocyte telomere length, measured at any age via quantitative polymerase chain reaction, or terminal restriction fragment analysis, either cross-sectionally, or longitudinally. Papers published before April 2017 were included. Results: Out of 230 abstracts assessed, 23 papers (32 estimates) were retained, from which 19 estimates were meta-analysed (15 cross-sectional, four longitudinal). Of the 15 cross-sectional estimates, seven reported on neonates: four used binary exposures of small-for-gestational-age vs. appropriate-for-gestational age (or appropriate- and large-for-gestational age), and three studied birth weight continuously. Eight estimates reported on childhood measures; five estimates were from studies of binary exposures (overweight/obese vs. non-obese children), and three studies used continuous measures of body mass index. All four longitudinal estimates were of neonatal adiposity, with two estimates for small-for-gestational-age vs. appropriate-for-gestational age neonates, and two estimates of birth weight studied continuously, in relation to adult telomere (49-61 years). There was no strong evidence of an association between neonatal or childhood adiposity, and telomere length. However, between study heterogeneity was high, and there were few combinable studies. Conclusions: Our systematic review and meta-analysis found no strong evidence of an association between neonatal or childhood adiposity and telomere length.

Validation of Minimally-Invasive Sample Collection Methods for Measurement of Telomere Length

Objective: The discovery of telomere length (TL) as a biomarker of cellular aging and correlate of age-related disease has generated a new field of research in the biology of healthy aging. Although the most common method of sample collection for TL is venous blood draw, less-invasive DNA collection methods are becoming more widely used. However, how TL relates across tissues derived from these sample collection methods is poorly understood. The current study is the first to characterize the associations in TL across three sample collection methods: venous whole blood, finger prick dried blood spot and saliva.

Methods: TL was measured in 24 healthy young adults using three modes of sample collection for each participant: venous whole blood, finger prick dried blood spot and saliva. Relative TL was measured using quantitative polymerase chain reaction.

Results: TL in finger prick dried blood spots (DBS) washighly correlated with TL in whole blood (r = 0.84, p < 0.001). Salivary TL was also correlated with whole blood TL (r = 0.56, p = 0.005), but this association was not as strong as that of dried blood spot TL (Steiger’s Z = 2.12, p = 0.034). TL was longer in saliva than in whole blood or DBS (p’s < 0.001).

Conclusions: These findings have important implications for future study design by supporting the validity of less-invasive methods that can be implemented with vulnerable populations or in the field. Further, these findings aid in interpreting the burgeoning area of biological aging research and may shed light on our understanding of inconsistencies in the empirical literature.

Shaping long-term primate development: Telomere length trajectory as an indicator of early maternal maltreatment and predictor of future physiologic regulation

The molecular, neurobiological, and physical health impacts of child maltreatment are well established, yet mechanistic pathways remain inadequately defined. Telomere length (TL) decline is an emerging molecular indicator of stress exposure with definitive links to negative health outcomes in maltreated individuals. The multiple confounders endemic to human maltreatment research impede the identification of causal pathways. This study leverages a unique randomized, cross-foster, study design in a naturalistic translational nonhuman primate model of infant maltreatment. At birth, newborn macaques were randomly assigned to either a maltreating or a competent control mother, balancing for sex, biological mother parenting history, and social rank. Offspring TL was measured longitudinally across the first 6 months of life (infancy) from peripheral blood. Hair cortisol accumulation was also determined at 6, 12, and 18 months of age. TL decline was greater in animals randomized to maltreatment, but also interacted with biological mother group. Shorter TL at 6 months was associated with higher mean cortisol levels through 18 months (juvenile period) when controlling for relevant covariates. These results suggest that even under the equivalent social, nutritional, and environmental conditions feasible in naturalistic translational nonhuman primate models, early adverse caregiving results in lasting molecular scars that foreshadow elevated health risk and physiologic dysregulation.

Correlation of cord blood telomere length with birth weight

Background

Intrauterine growth restriction affects 3% of newborns; and the lightest 10% of whom are classified as small for gestational age (SGA). These low-birth weight newborns are at increased risk of neonatal morbidity such as hypoxia and hypoglycaemia. In later life, they are at higher risk of several age-related diseases such as cardiovascular and metabolic disorders and dementia. As having short telomeres is also associated with these diseases, we tested if these newborns might already start with shorter telomeres at birth.

Findings

Relative telomere lengths were determined using quantitative real-time PCR in cord blood samples from 195 newborns of Chinese ancestry. Based on the telomere length normalised to a single copy gene and a reference DNA sample as internal control, we found statistically significant correlations between relative telomere length and both unadjusted and gestational age-adjusted birth weight, with the lighter newborns having shorter telomeres. The SGA birth weight group comprising the bottom 10% of the samples also had the shortest telomeres compared to the medium and heaviest birth weight groups.

Conclusions

Our results indicate that there is reduction of cord blood telomere length for newborns with lower birth weight.

Preterm infants have significantly longer telomeres than their term born counterparts

There are well-established morbidities associated with preterm birth including respiratory, neurocognitive and developmental disorders. However several others have recently emerged that characterise an 'aged' phenotype in the preterm infant by term-equivalent age. These include hypertension, insulin resistance and altered body fat distribution. Evidence shows that these morbidities persist into adult life, posing a significant public health concern. In this study, we measured relative telomere length in leukocytes as an indicator of biological ageing in 25 preterm infants at term equivalent age. Comparing our measurements with those from 22 preterm infants sampled at birth and from 31 term-born infants, we tested the hypothesis that by term equivalent age, preterm infants have significantly shorter telomeres (thus suggesting that they are prematurely aged). Our results demonstrate that relative telomere length is highly variable in newborn infants and is significantly negatively correlated with gestational age and birth weight in preterm infants. Further, longitudinal assessment in preterm infants who had telomere length measurements available at both birth and term age (n = 5) suggests that telomere attrition rate is negatively correlated with increasing gestational age. Contrary to our initial hypothesis however, relative telomere length was significantly shortest in the term born control group compared to both preterm groups and longest in the preterm at birth group. In addition, telomere lengths were not significantly different between preterm infants sampled at birth and those sampled at term equivalent age. These results indicate that other, as yet undetermined, factors may influence telomere length in the preterm born infant and raise the intriguing hypothesis that as preterm gestation declines, telomere attrition rate increases.

The differential impact of oxytocin receptor gene in violence-exposed boys and girls

Childhood violence exposure is a prevalent public health problem. Understanding the lasting impact of violence requires an enhanced appreciation for the complex effects of violence across behavioral, physiologic, and molecular outcomes. This subject matched, cross-sectional study of 80 children explored the impact of violence exposure across behavioral, physiologic, and cellular outcomes. Externalizing behavior, diurnal cortisol rhythm, and telomere length (TL) were examined in a community recruited cohort of Black youth. Given evidence that genetic variation contributes to individual differences in response to the environment, we further tested whether a polymorphism in the oxytocin receptor gene (OXTR rs53576) moderated associations between violence and youth outcomes. Exposure to violence was directly associated with increased externalizing behavior, but no direct association of violence was found with cortisol or TL. Oxytocin genotype, however, moderated the association between violence and both cortisol and TL, suggesting that pathways linked to oxytocin may contribute to individual differences in the physiologic and molecular consequences of violence exposure. Sex differences with OXTR in cortisol and TL outcomes were also detected. Taken together, these findings suggest that there are complex pathways through which violence exposure impacts children, and that these pathways differ by both genetic variation and the sex of the child.

Diverse Aging and Health Inequality by Race and Ethnicity

Although gerontologists have long embraced the concept of heterogeneity in theories and models of aging, recent research reveals the importance of racial and ethnic diversity on life course processes leading to health inequality. This article examines research on health inequality by race and ethnicity and identifies theoretical and methodological innovations that are transforming the study of health disparities. Drawing from cumulative inequality theory, we propose greater use of life course analysis, more attention to variability within racial and ethnic groups, and better integration of environmental context into the study of accumulation processes leading to health disparities.

Differences in placental telomere length suggest a link between racial disparities in birth outcomes and cellular aging

BACKGROUND

Health disparities begin early in life and persist across the life course. Despite current efforts, black women exhibit greater risk for pregnancy complications and negative perinatal outcomes compared with white women. The placenta, which is a complex multi-tissue organ, serves as the primary transducer of bidirectional information between the mother and fetus. Altered placental function is linked to multiple racially disparate pregnancy complications; however, little is known about racial differences in molecular factors within the placenta. Several pregnancy complications, which include preeclampsia and fetal growth restriction, exhibit racial disparities and are associated with shorter placental telomere length, which is an indicator of cellular stress and aging. Cellular senescence and telomere dynamics are linked to the molecular mechanisms that are associated with the onset of labor and parturition. Further, racial differences in telomere length are found in a range of different peripheral tissues. Together these factors suggest that exploration of racial differences in telomere length of the placenta may provide novel mechanistic insight into racial disparities in birth outcomes.

OBJECTIVE

This study examined whether telomere length measured in 4 distinct fetally derived tissues were significantly different between black and white women. The study had 2 hypotheses: (1) that telomere length that is measured in different placental tissue types would be correlated and (2) that across all sampled tissues telomere length would differ by race.

STUDY DESIGN

In a prospective study, placental tissue samples were collected from the amnion, chorion, villus, and umbilical cord from black and white singleton pregnancies (N=46). Telomere length was determined with the use of monochrome multiplex quantitative real-time polymerase chain reaction in each placental tissue. Demographic and pregnancy-related data were also collected. Descriptive statistics characterized the sample overall and among black and white women separately. The overall impact of race was assessed by multilevel mixed-effects linear regression models that included empirically relevant covariates.

RESULTS

Telomere length was correlated significantly across all placental tissues. Pairwise analyses of placental tissue telomere length revealed significantly longer telomere length in the amnion compared with the chorion (t=-2.06; P=.043). Overall telomere length measured in placenta samples from black mothers were significantly shorter than those from white mothers (β=-0.09; P=.04). Controlling for relevant maternal and infant characteristics strengthened the significance of the observed racial differences (β=-0.12; P=.02). Within tissue analyses revealed that the greatest difference by race was found in chorionic telomere length (t=-2.81; P=.007).

CONCLUSION

These findings provide the first evidence of racial differences in placental telomere length. Telomere length was significantly shorter in placental samples from black mothers compared with white mothers. Given previous studies that have reported that telomere length, cellular senescence, and telomere dynamics are molecular factors that contribute to the rupture of the amniotic sac, onset of labor, and parturition, our findings of shorter telomere length in placentas from black mothers suggest that accelerated cellular aging across placental tissues may be relevant to the increased risk of preterm delivery in black pregnancies. Our results suggest that racial differences in cellular aging in the placenta contribute to the earliest roots of health disparities.

Maternal Social Disadvantage and Newborn Telomere Length in Archived Dried Blood Spots from the Michigan Neonatal Biobank

Telomeres are the protective caps at the ends of eukaryotic chromosomes. Short telomere length is associated with morbidity and mortality among adults and may mark the biological impact of social experiences. Using archived dried blood spots from the Michigan Neonatal Biobank, this study examined markers of maternal social disadvantage (educational attainment, receipt of public assistance, marital status, and race/ethnicity) from linked birth certificates as predictors of telomere length at birth in a sample of 192 singleton neonates born to non-Hispanic black, non-Hispanic white, and Latina mothers aged 20-35 years. Consistent with two recent studies in newborns, but counter to the idea that maternal social disadvantage is associated with shorter offspring telomere length, we found that infants born to black mothers had longer telomeres than those born to white mothers (b = 0.12, SE = 0.06, p = .05). However, black/white differences in newborn telomere length varied by receipt of public assistance. Among newborns whose mothers received WIC and/or Medicaid, there were no significant black/white differences in telomere length (b = 0.09, SE = 0.08, p = .25). In contrast, among those whose mothers did not receive public assistance-just 6 out of 69 infants born to black mothers versus 41 out of 69 infants born to white mothers-we found that babies born to black mothers had longer telomere length than babies born to white mothers (b = 0.37, SE = 0.16, p = .03). The interaction between black race/ethnicity and receipt of public assistance did not reach the conventional threshold for statistical significance (b = -0.22, SE = 0.15, p = .13), suggesting that this finding may be due to chance. No other markers of maternal social disadvantage were related to infant telomere length. Although replication of these results in a larger sample with more infants born to black mothers with relatively high socioeconomic status is needed, this study offers preliminary support for the hypothesis that race/ethnic differences in newborn telomere length depend on social context.