Association between prenatal particulate air pollution exposure and telomere length in cord blood: Effect modification by fetal sex

In-Utero exposure to potential sources of indoor air pollution and umbilical cord blood leukocyte telomere length

Indoor air pollution (IAP) has been associated with various adverse health effects. However, the evidence regarding such an association with leukocyte telomere length (LTL) in cord blood samples is still scarce. Therefore, the present study aimed to assess the relationship between exposure to indicators of IAP and LTL in umbilical cord blood samples. This cross-sectional study was based on 188 mother-newborn pairs who participated in our study between 2020 and 2022 in Isfahan, Iran. Umbilical LTL was measured by quantitative real-time polymerase chain reaction (qRT-PCR) technique. Linear mixed-effect models were used to assess the relationship between IAP indicators and umbilical LTL, adjusted for relevant covariates. The median (interquartile range (IQR)) of umbilical LTL was 0.92 (0.47). In fully adjusted models, frequency of using degreasing spray during pregnancy (times per month) (β = -0.047, 95% CI:0.09, -0.05, P-value = 0.02), using air freshener spray during pregnancy (β = -0.26, 95% CI: -0.5, -0.02, P-value = 0.03) and frequency of using insecticides during pregnancy (times per month) (β = -0.025, 95% CI: -0.047, -0.003, P-value = 0.02) were significantly associated with shorter umbilical LTL. There was a positive significant relationship between the frequency of using cleaning spray during pregnancy (times per month) with umbilical LTL (β = 0.019, 95% CI: 0.005, 0.033, P-value = 0.01). Furthermore, the direct connection of the parking with home and the frequency of using barbecue (times per week) were marginally associated with shorter umbilical LTL. For other indicators of IAP, we did not observe any statistically significant associations. Overall, this study suggested a negative association between prenatal exposure to IAP during pregnancy and umbilical LTL.

Sex-specific effects of maternal blood pressure on newborn telomere length: A prospective study

OBJECTIVE

To investigate the relationship between maternal blood pressure (BP) and neonatal cord blood telomere length (TL) during pregnancy, and to clarify the sensitive period.

METHODS

We conducted a prospective cohort study with 621 mother-newborn pairs from the Guangxi Zhuang Birth Cohort (GZBC) in China. Multiple informant models, restricted cubic spline regression (RCS) models, and quantile regression models were conducted to analyze the correlation between maternal BP and neonatal TL.

RESULTS

Maternal diastolic blood pressure (DBP) was inversely related to neonatal cord blood TL in the second trimester (P = 0.015) and the third trimester (P = 0.011). There was a male-specific relationship between maternal BP and neonatal TL. A 1 mmHg increment in maternal systolic blood pressure (SBP) and DBP during the second trimester was related with 0.42% (95% CI: -0.80%, -0.04%) and 0.61% (95% CI: -1.13%, -0.09%) shorter TL in male newborns, respectively. Per unit increase of maternal DBP during the third trimester was related with 0.54% (95% CI: -1.03%, -0.05%) shorter TL in male newborns. Pregnant women with hypertensive disease of pregnancy (HDP) had male offspring with shorter TL (P = 0.003). However, no significant relationships were found in female newborns (P = 0.570).

CONCLUSION

Maternal BP during pregnancy is inversely correlated with male neonatal TL and the second and third trimesters are sensitive windows.

Exposure to pollution during the first thousand days and telomere length regulation: A literature review

Telomere length (TL) is a biomarker for cellular senescence and TL erosion is predictive of the risk for age-related diseases. Despite being genetically determined at birth, TL may be susceptible to modifications through epigenetic mechanisms. Pollutant agents are considered one of the major threats to both human and planetary health. Their ability to cross the placental barrier and induce oxidative stress in fetal cells is particularly concerning and it may be associated with early TL erosion. In consideration of the timely relevance of this topic, we conducted a literature review on the impact of prenatal exposure to pollutant agents on newborn TL. The search yielded a total of 1099 records, of which only 32 met the inclusion criteria for the review. These criteria included the participation of human subjects, a longitudinal design or collection of longitudinal data, reporting of original TL data, and a focus on exposure to pollutant agents. The majority of the studies reported a significant inverse association between prenatal exposure to pollutant agents and TL. Furthermore, the second trimester of pregnancy emerged as a special sensitive period for the occurrence of pollutant agent-driven TL modifications. Sex differences were inconsistently reported across studies. This review contributes to highlighting biochemical pathways for the threats of environmental pollution to human health. Future research is warranted to further highlight potential buffering mechanisms.

Outdoor fine particulate matter exposure and telomere length in humans: A systematic review and meta-analysis

Although the association between changes in human telomere length (TL) and ambient fine particulate matter (PM2.5) has been documented, there remains disagreement among the related literature. Our study conducted a systematic review and meta-analysis of epidemiological studies to investigate the health effects of outdoor PM2.5 exposure on human TL after a thorough database search. To quantify the overall effect estimates of TL changes associated with every 10 μg/m3 increase in PM2.5 exposure, we focused on two main topics, which were outdoor long-term exposure and prenatal exposure of PM2.5. Additionally, we included a summary of short-term PM2.5 exposure and its impact on TL due to limited data availability. Our qualitative analysis included 20 studies with 483,600 participants. The meta-analysis showed a statistically significant association between outdoor PM2.5 exposure and shorter human TL, with pooled impact estimates (β) of -0.12 (95% CI: -0.20, -0.03, I2= 95.4%) for general long-term exposure and -0.07 (95% CI: -0.15, 0.00, I2= 74.3%) for prenatal exposure. In conclusion, our findings suggest that outdoor PM2.5 exposure may contribute to TL shortening, and noteworthy associations were observed in specific subgroups, suggesting the impact of various research variables. Larger, high-quality studies using standardized methodologies are necessary to strengthen these conclusions further.

Prenatal exposure to air pollution and BWGA Z-score: Modifying effects of placenta leukocyte telomere length and infant sex

BACKGROUND

Air pollutants, such as fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3), have been associated with adverse birth outcomes, including low birth weight, often exhibiting sex-specific effects. However, the modifying effect of placental telomere length (TL), reflecting cumulative lifetime oxidative stress in mothers, remains unexplored.

METHOD

Using data from a Northeastern U.S. birth cohort (n = 306), we employed linear regression and weighted quantile sum models to assess trimester-average air pollution exposures and birth weight for gestational age (BWGA) z-scores. Placental TL, categorized by median split, was considered as an effect modifier. Interactions among air pollutants, placental TL, infant sex, and BWGA z-score were evaluated.

RESULTS

Without placental TL as a modifier, only 1st trimester O3 was significantly associated with BWGA z-scores (coefficient: 0.33, 95% CI: 0.03, 0.63). In models considering TL interactions, a significant modifying effect was observed between 3rd trimester NO2 and BWGA z-scores (interaction p-value = 0.02). Specifically, a one interquartile range (1-IQR) increase in 3rd trimester NO2 was linked to a 0.28 (95% CI: 0.06, 0.52) change in BWGA z-score among shorter placental TL group, with no significant association among longer TL group. Among male infants, there were significant associations between 3rd trimester PM2.5 exposure and BWGA z-scores in the longer TL group (coefficient: -0.34, 95% CI: -0.61, -0.02), and between 1st trimester O3 exposure and BWGA z-scores among males in the shorter TL group (coefficient: 0.59, 95% CI: 0.06, 1.08). For females, only a negative association in 2nd trimester mixture model was observed within the longer TL group (coefficient: -0.10, 95% CI: -0.21, -0.01).

CONCLUSION

These findings highlight the need to consider the complex interactions among prenatal air pollutant exposures, placental TL, and fetal sex to better elucidate those at greatest risk for adverse birth outcomes.

Prenatal air pollution exposure in relation to the telomere-mitochondrial axis of aging at birth: A systematic review

BACKGROUND

Telomere length (TL) and mitochondrial DNA (mtDNA) are central markers of vital biological mechanisms, including cellular aging. Prenatal air pollution exposure may impact molecular markers of aging leading to adverse health effects.

OBJECTIVE

To perform a systematic review on human population-based studies investigating the association between prenatal air pollution exposure and TL or mtDNA content at birth.

METHODOLOGY

Searches were undertaken on PubMed and Web of Science until July 2023. The framework of the review was based on the PRISMA-P guidelines.

RESULTS

Nineteen studies studied prenatal air pollution and TL or mtDNA content at birth. Studies investigating TL or mtDNA content measured at any other time or did not evaluate prenatal air pollution were excluded. Twelve studies (including 4381 participants with study sample range: 97 to 743 participants) investigated newborn TL and eight studies (including 3081 participants with study sample range: 120 to 743 participants) investigated mtDNA content at birth. Seven studies focused on particulate matter (PM2.5) exposure and newborn TL of which all, except two, showed an inverse association in at least one of the gestational trimesters. Of the eight studies on mtDNA content, four focused on PM2.5 air pollution with two of them reporting an inverse association. For PM2.5 exposure, observations on trimester-specific effects were inconsistent. Current literature showing associations with other prenatal air pollutants (including nitrogen oxides, sulfur dioxide, carbon monoxide and ozone) is inconsistent.

CONCLUSION

This review provides initial evidence that prenatal PM2.5 exposure impacts the telomere-mitochondrial axis of aging at birth. The current evidence did not reveal harmonious observations for trimester-specific associations nor showed consistent effects of other air pollutants. Future studies should elucidate the specific contribution of prenatal exposure to pollutants other than PM in relation to TL and mtDNA content at birth, and the potential later life health consequences.

WITHDRAWN: Exposure to Ambient Particulate Matter during Pregnancy: Implications for Infant Telomere Length

This manuscript has been withdrawn by the authors as it was submitted and made public without the full consent of all the authors. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author. The authors have an approved version for citation that is peer reviewed. Ahlers, N.E.; Lin, J.; Weiss, S.J. Exposure to Ambient Particulate Matter during Pregnancy: Implications for Infant Telomere Length. Air 2024, 2, 24-37. https://doi.org/10.3390/air2010002.

Effect of Particulate Matter 2.5 on Fetal Growth in Male and Preterm Infants through Oxidative Stress

Particulate matter 2.5 (PM2.5) levels are associated with adverse pregnancy outcomes. In this retrospective cohort study, we examined whether the concentration of indoor PM2.5 affected pregnancy outcomes. Additionally, we evaluated biomarkers of pregnancy-related complications caused by fine dust. We collected clinical information and data based on residential addresses from the Air Korea database to assess PM2.5 exposure levels. As a multicenter prospective cohort study, we measured the indoor PM2.5 concentration and inflammatory and oxidative stress markers. The PM2.5 concentration of the low-birth-weight (LBW) delivery group was 27.21 μg/m3, which was significantly higher than that of the normal-birth-weight (NBW) group (26.23 μg/m3) (p = 0.02). When the newborns were divided by sex, the PM2.5 concentration of the LBW group was 27.89 μg/m3 in male infants, which was significantly higher than that of the NBW group (26.26 μg/m3) (p = 0.01). In the prospective study, 8-hydroxy-2-deoxyguanosine significantly increased in the high-concentration group (113.55 ng/mL, compared with 92.20 ng/mL in the low-concentration group); in the high-concentration group, the rates of preterm birth (PTB) and small size for gestational age significantly increased (p < 0.01, p = 0.01). This study showed an association between PM2.5, oxidative stress, and fetal growth, with the PTB group being more vulnerable.

Ambient air pollution, genetic risk and telomere length in UK biobank

BACKGROUND

Telomere length (TL) is a biomarker of genomic aging. The evidence on the association between TL and air pollution was inconsistent. Besides, the modification effect of genetic susceptibility on the air pollution-TL association remains unknown.

OBJECTIVE

We aimed to evaluate the association of ambient air pollution with TL and further assess the modification effect of genetic susceptibility.

METHODS

433,535 participants with complete data of TL and air pollutants in UK Biobank were included. Annual average exposure of NO2, NOx, PM10 and PM2.5 was estimated by applying land use regression models. Genetic risk score (GRS) was constructed using reported telomere-related SNPs. Leukocyte TL was measured by quantitative polymerase chain reaction (qPCR). Multivariable linear regression models were employed to conduct associational analyses.

RESULTS

Categorical exposure models and RCS models both indicated U-shaped (for NO2 and NOx) and L-shaped (for PM10 and PM2.5) correlations between air pollution and TL. In comparison to the lowest quartile, the 2nd and 3rd quartile of NO2 (q2: -1.3% [-2.1%, -0.4%]; q3: -1.2% [-2.0%, -0.3%], NOx (q2: -1.3% [-2.1%, -0.5%]; q3: -1.4% [-2.2%, -0.5%]), PM2.5 (q2: -0.8% [-1.7%, 0.0%]; q3: -1.3% [-2.2%, -0.5%]), and the third quartile of PM10 (q3: -1.1% [-1.9%, -0.2%]) were inversely associated with TL. The highest quartile of NO2 was positively correlated with TL (q4: 1.0% [0.0%, 2.0%]), whereas the negative correlation between the highest quartile of other pollutants and TL was also attenuated and no longer significant. In the genetic analyses, synergistic interactions were observed between the 4th quartile of three air pollutants (NO2, NOx, and PM2.5) and genetic risk.

IMPACT STATEMENT

Our study for the first time revealed a non-linear trend for the association between air pollution and telomere length. The genetic analyses suggested synergistic interactions between air pollution and genetic risk on the air pollution-TL association. These findings may shed new light on air pollution's health effects, offer suggestions for identifying at-risk individuals, and provide hints regarding further investigation into gene-environment interactions.

Early Environment and Telomeres: a Long-Term Toxic Relationship

PURPOSE OF REVIEW

Telomere length (TL) shortening is a hallmark of biological aging. While studies have extensively focused on the impact of environmental exposures on TL in older populations, consistent evidence indicates that prenatal environmental exposures to air pollutants, polycyclic aromatic hydrocarbons, metals, and endocrine-disrupting chemicals influence TL shortening. Here, we summarize evidence linking prenatal environmental exposures with children's TL and discuss potential long-term effects.

RECENT FINDINGS

Current evidence shows that prenatal environmental exposures alter TL and identify pregnancy as a critical window of susceptibility for telomere damage in children. However, results vary across studies, possibly depending on the source, exposure time window, and stage evaluated. Additional research is needed to investigate whether early TL alterations mediate long-term health effects of offspring. Prenatal environmental exposures induce early childhood changes in TL. Based on known links between TL and biological aging, these alterations may have long-term impact on individuals' health throughout life.

Association between rare earth element exposure during pregnancy and newborn telomere length

Telomere length (TL) is considered a marker of biological aging and lifetime health, and some epidemiological studies report that the environmental exposures may influence TL at birth. We aimed to investigate the associations between prenatal rare earth elements (REE) exposure and newborn TL. A total of 587 mother-newborn pairs were recruited during 2013 to 2015 in Wuhan, China. Maternal urinary concentrations of REE collected during three trimesters were measured by inductively coupled plasma mass spectrometry. Quantitative real-time polymerase chain reaction was used to measure relative cord blood TL. The trimester-specific associations between prenatal REE exposure and cord blood TL were evaluated using multiple informant models. Weighted quantile sum regression was used to estimate the mixture effect of urinary REE on cord blood TL. After adjustment for potential confounders, per doubling of urinary REE (Dy, Yb, Pr, Nd, and Tm) concentrations (μg/g creatinine) during the second trimester was respectively associated with 1.94% (95% CI 0.19%, 3.72%), 2.10% (95% CI 0.31%, 3.92%), 2.11% (95% CI 0.35%, 3.89%), 2.08% (95% CI 0.01%, 4.20%), and 1.38% (95% CI 0.09%, 2.70%) increase in cord blood TL. Furthermore, exposure to the mixture of REE during the second trimester was also significantly associated with increased cord blood TL (percent change 1.20%, 95% CI 0.30%, 2.11%). However, these associations were not statistically significant in the first and third trimesters. This study provides new evidence on the potential effect of prenatal REE exposure on the initial (newborn) setting of offspring's telomere biology. Further epidemiological studies are warranted to confirm our findings.

Ambient air pollution exposure and telomere length: a systematic review and meta-analysis

OBJECTIVE

This study aimed to provide evidence of the associations between pre- and post-birth and adulthood air pollution exposure with telomere length.

STUDY DESIGN

The databases of PubMed, Embase, and Web of Science were searched up to June 1st, 2022 in order to include relevant observational studies and perform a systematic review and meta-analysis.

METHODS

The random-effects meta-analysis was grouped by air pollutant and exposure window (pre- and post-birth and adulthood) to evaluate the summary effect estimate. Cochran's Q and I² statistics were used to evaluate the heterogeneity among the included studies. The quality of individual studies was evaluated using the national toxicology program/office of health assessment and translation risk of bias rating tool.

RESULTS

We identified 18 studies, covering 8506 children and 2263 adults from multiple countries. We found moderate evidence that particulate matter less than 2.5 μm (PM_2.5) exposure during the entire pregnancy (-0.043, 95% CI: -0.067, -0.018), nitrogen dioxide (NO₂) exposure during the first trimester (-0.016, 95% confidence interval [CI]: -0.027, -0.005), long-term adulthood PM_2.5 exposure were associated with shortening telomere length. Mild to high between-study heterogeneity was observed for the most tested air pollutant-telomere length combinations in different exposure windows.

CONCLUSIONS

This systematic review and meta-analysis provides the evidence which strongly supports that prenatal PM_2.5 and NO₂ exposures were related to reduced telomere length, while prenatal sulfur dioxide (SO₂) and carbon monoxide (CO) exposures, childhood PM_2.5, particulate matter less than 10 μm (PM₁₀), NO₂ exposures and short-term adulthood PM_2.5 and PM₁₀ exposures were not associated with telomere length. Further high-quality studies are needed to elaborate our suggestive associations.

The association between ambient particulate matter exposure and the telomere-mitochondrial axis of aging in newborns

BACKGROUND

Particulate matter (PM) is associated with aging markers at birth, including telomeres and mitochondria. It is unclear whether markers of the core-axis of aging, i.e. tumor suppressor p53 (p53) and peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α), are associated with prenatal air pollution and whether there are underlying mechanisms.

METHODS

556 mother-newborn pairs from the ENVIRONAGE birth cohort were recruited at the East Limburg Hospital in Genk (Belgium). In placenta and cord blood, telomere length (TL) and mitochondrial DNA content (mtDNAc) were measured using quantitative real-time polymerase chain reaction (qPCR). In cord plasma, p53 and PGC-1α protein levels were measured using ELISA. Daily ambient PM_2.5 concentrations during gestation were calculated using a spatial temporal interpolation model. Distributed lag models (DLMs) were applied to assess the association between prenatal PM_2.5 exposure and each molecular marker. Mediation analysis was performed to test for underlying mechanisms.

RESULTS

A 5 µg/m³ increment in PM_2.5 exposure was associated with -11.23 % (95 % CI: -17.36 % to -4.65 %, p = 0.0012) and -7.34 % (95 % CI: -11.56 % to -2.92 %, p = 0.0014) lower placental TL during the entire pregnancy and second trimester respectively, and with -12.96 % (95 % CI: -18.84 % to -6.64 %, p < 0.001) lower placental mtDNAc during the third trimester. Furthermore, PM_2.5 exposure was associated with a 12.42 % (95 % CI: -1.07 % to 27.74 %, p = 0.059) higher cord plasma p53 protein level and a -3.69 % (95 % CI: -6.97 % to -0.31 %, p = 0.033) lower cord plasma PGC-1α protein level during the third trimester. Placental TL mediated 65 % of the negative and 17 % of the positive association between PM_2.5 and placental mtDNAc and cord plasma p53 protein levels, respectively.

CONCLUSION

Ambient PM_2.5 exposure during pregnancy is associated with markers of the core-axis of aging, with TL as a mediating factor. This study strengthens the hypothesis of the air pollution induced core-axis of aging, and may unravel a possible underlying mediating mechanism in an early-life epidemiological context.

Neuroinflammation and Neurodegeneration of the Central Nervous System from Air Pollutants: A Scoping Review

In this scoping review, we provide a selective mapping of the global literature on the effects of air pollution on the life-span development of the central nervous system. Our synthesis first defines developmental neurotoxicants and the model effects of particulate matter. We then discuss air pollution as a test bench for neurotoxicants, including animal models, the framework of systemic inflammation in all affected organs of the body, and the cascade effects on the developing brain, with the most prevalent neurological structural and functional outcomes. Specifically, we focus on evidence on magnetic resonance imaging and neurodegenerative diseases, and the links between neuronal apoptosis and inflammation. There is evidence of a developmental continuity of outcomes and effects that can be observed from utero to aging due to severe or significant exposure to neurotoxicants. These substances alter the normal trajectory of neurological aging in a propulsive way towards a significantly higher rate of acceleration than what is expected if our atmosphere were less polluted. The major aggravating role of this neurodegenerative process is linked with the complex action of neuroinflammation. However, most recent evidence learned from research on the effects of COVID-19 lockdowns around the world suggests that a short-term drastic improvement in the air we breathe is still possible. Moreover, the study of mitohormesis and vitagenes is an emerging area of research interest in anti-inflammatory and antidegenerative therapeutics, which may have enormous promise in combatting the deleterious effects of air pollution through pharmacological and dietary interventions.

Effects of air pollution on telomere length: Evidence from in vitro to clinical studies

Air pollution remains the major environmental problem globally. There is extensive evidence showing that the variety of air pollutants from environmental and occupational exposures cause adverse effects to our health. The clinical symptoms of those effects may present at a late stage, so surveillance is difficult to manage. Several biomarkers have been used for the early detection of health issues following exposure to air pollution, including the use of telomere length which indicates cellular senescence in response to oxidative stress. Oxidative stress is one of the most plausible mechanisms associated with exposure to air pollutants. Some specific contexts including age groups, gender, ethnicity, occupations, and health conditions, showed significant alterations in telomere length after exposure to air pollutants. Several reports demonstrated both negative and positive associations between telomere length and air pollution, the studies using different concentrations and exposure times to air pollution on the study of telomere lengths. Surprisingly, some studies reported that low levels of exposure to air pollutants (lower than regulated levels) caused the alterations in telomere length. Those findings suggest that telomere length could be one of most practical biomarkers in air pollution surveillance. Therefore, this review aimed to summarize and discuss the relationship between telomere length and exposure to air pollution. The knowledge from this review will be beneficial for the planning of public health to reduce health problems in the general population, particularly in vulnerable people, who still live in areas with high air pollution.

Life-course exposure to air pollution and biological ageing in the Lothian Birth Cohort 1936

BACKGROUND

Exposure to air pollution is associated with a range of diseases. Biomarkers derived from DNA methylation (DNAm) offer potential mechanistic insights into human health differences, connecting disease pathogenesis and biological ageing. However, little is known about sensitive periods during the life course where air pollution might have a stronger impact on DNAm, or whether effects accumulate over time. We examined associations between air pollution exposure across the life course and DNAm-based markers of biological ageing.

METHODS

Data were derived from the Scotland-based Lothian Birth Cohort 1936. Participants' residential history was linked to annual levels of fine particle (PM_2.5), sulphur dioxide (SO₂), nitrogen dioxide (NO₂), and ozone (O₃) around 1935, 1950, 1970, 1980, 1990, and 2001; pollutant concentrations were estimated using the EMEP4UK atmospheric chemistry transport model. Blood samples were obtained between ages of 70 and 80 years, and Horvath DNAmAge, Hannum DNAmAge, DNAmPhenoAge, DNAmGrimAge, and DNAm telomere length (DNAmTL) were computed. We applied the structured life-course modelling approach: least angle regression identified best-fit life-course models for a composite measure of air pollution (air quality index [AQI]), and mixed-effects regression estimated selected models for AQI and single pollutants.

RESULTS

We included 525 individuals with 1782 observations. In the total sample, increased air pollution around 1970 was associated with higher epigenetic age (AQI: b = 0.322 year, 95 %CI: 0.088, 0.555) measured with Horvath DNAmAge in late adulthood. We found shorter DNAmTL among males with higher air pollution around 1980 (AQI: b = -0.015 kilobase, 95 %CI: -0.027, -0.004) and among females with higher exposure around 1935 (AQI: b = -0.017 kilobase, 95 %CI: -0.028, -0.006). Findings were more consistent for the pollutants PM_2.5, SO₂ and NO₂.

DISCUSSION

We tested the life-course relationship between air pollution and DNAm-based biomarkers. Air pollution around birth and in young-to-middle adulthood is linked to accelerated epigenetic ageing and telomere-associated ageing in later life.

Prenatal exposure to air pollution is associated with altered brain structure, function, and metabolism in childhood

BACKGROUND

Prenatal exposure to air pollution disrupts cognitive, emotional, and behavioral development. The brain disturbances associated with prenatal air pollution are largely unknown.

METHODS

In this prospective cohort study, we estimated prenatal exposures to fine particulate matter (PM_2.5 ) and polycyclic aromatic hydrocarbons (PAH), and then assessed their associations with measures of brain anatomy, tissue microstructure, neurometabolites, and blood flow in 332 youth, 6-14 years old. We then assessed how those brain disturbances were associated with measures of intelligence, ADHD and anxiety symptoms, and socialization.

RESULTS

Both exposures were associated with thinning of dorsal parietal cortices and thickening of postero-inferior and mesial wall cortices. They were associated with smaller white matter volumes, reduced organization in white matter of the internal capsule and frontal lobe, higher metabolite concentrations in frontal cortex, reduced cortical blood flow, and greater microstructural organization in subcortical gray matter nuclei. Associations were stronger for PM_2.5 in boys and PAH in girls. Youth with low exposure accounted for most significant associations of ADHD, anxiety, socialization, and intelligence measures with cortical thickness and white matter volumes, whereas it appears that high exposures generally disrupted these neurotypical brain-behavior associations, likely because strong exposure-related effects increased the variances of these brain measures.

CONCLUSIONS

The commonality of effects across exposures suggests PM_2.5 and PAH disrupt brain development through one or more common molecular pathways, such as inflammation or oxidative stress. Progressively higher exposures were associated with greater disruptions in local volumes, tissue organization, metabolite concentrations, and blood flow throughout cortical and subcortical brain regions and the white matter pathways interconnecting them. Together these affected regions comprise cortico-striato-thalamo-cortical circuits, which support the regulation of thought, emotion, and behavior.

Telomere length and mitochondrial DNA copy number in bipolar disorder: A sibling study

OBJECTIVES

An accelerated cellular ageing has been observed in bipolar disorder (BD) using biomarkers such as telomere length (TL) and mitochondrial DNA copy number (mtDNAcn). Several risk factors might drive premature ageing in individuals with BD, including a familial predisposition. This study compared TL and mtDNAcn between individuals with BD and their (un)-affected siblings, and explored factors that may explain proband-sibling differences.

METHODS

Sixty individuals with BD and seventy-four siblings (34 affected with BD or mood disorders and 40 unaffected) were included. Quantitative polymerase chain reaction (qPCR) was used to measure TL and mtDNAcn from peripheral blood genomic DNA.

RESULTS

TL and mtDNAcn did not significantly differ between probands and their siblings, whatever these latter were affected or not with mood disorders. However, the correlation plots of TL or mtDNAcn in proband-sibling pairs suggested that some pairs were discordant. The within proband-sibling pairs differences for TL and mtDNAcn were not explained by differences in all tested factors.

CONCLUSIONS

This study shows that probands with BD and their siblings are concordant for TL and mtDNAcn suggesting that they may share some environmental or genetic determinants of these two biomarkers of cellular ageing.

Ambient ozone exposure during pregnancy and telomere length in newborns: a prospective investigation in Wuhan, China

Recent studies suggest that environmental exposures, including air pollution, may influence initial (newborn) telomere length (TL), which has important implications for lifetime health. However, the effect of prenatal ozone exposure on newborn TL is unclear. This study aimed to examine the association of ozone exposure during pregnancy with newborn TL. We used data from a birth cohort study of 762 mother-newborn pairs performed in Wuhan, China, during 2013-2015. Land-use regression models were used to assess prenatal ozone exposure. Newborn TL was quantified in cord blood by qPCR assay. We applied multiple informant model to explore the relationship of prenatal ozone exposure with newborn TL. After adjustment for potential confounders, an interquartile range (IQR) increase in ozone exposure during the 2nd trimester, 3rd trimester, and whole pregnancy were associated with 6.00% (95% confidence interval [CI]: 1.59%, 10.62%), 12.64% (95% CI: 7.52%, 18.00%), and 7.10% (95% CI: 4.09%, 10.20%) longer cord blood TL, respectively. In contrast, an IQR increase in ozone exposure during the 1st trimester was associated with a 8.39% (95% CI: - 12.90%, - 3.65%) shorter cord blood TL. In multipollutant models, consistent associations were observed between ozone exposures during the 2nd trimester and whole pregnancy and cord blood TL, but not significant for the 1st and 3rd trimesters. In conclusion, our findings suggest positive associations of ozone exposure during the 2nd trimester, 3rd trimester, and whole pregnancy with newborn TL and a negative association during the 1st trimester. This study provides new evidence in humans for a potential "programming" mechanism linking maternal ozone exposure to the initial (newborn) setting of offspring's telomere biology.

Association between telomere length in human umbilical cord tissues and polychlorinated biphenyls in maternal and cord serum

Environmental exposure to persistent organic pollutants during pregnancy has potential adverse health effects on the fetus. One of the environmental pollutants is polychlorinated biphenyl (PCB). Earlier, we reported the presence of PCBs in fetal tissues such as the umbilical cord. Telomere length (TL) is a biomarker of aging because it shortens with each cell division. According to the Developmental Origins of Health and Disease hypothesis, fetal exposure to environmental pollutants during pregnancy affects the occurrence of non-communicable diseases in later life. In the current study, we investigated the association between cord tissue TL and serum levels of PCBs. The subjects were 114 mother-child pairs participating in a birth cohort study, the Chiba Study of Mother and Child Health (C-MACH). Maternal serum was collected during pregnancy, and cord serum and tissue were obtained at birth. TL was assessed by qPCR using genomic DNA extracted from the cord tissue. Maternal and cord serum PCB congener levels were assessed using gas chromatography and negative ion chemical ionization qMS. In male fetuses, serum levels of PCB74 in the cord blood were significantly associated with TL following covariate adjustment, but no significant association was found in female fetuses. These data suggest that the TL of the umbilical cord is affected by fetal exposure to PCBs.

Prenatal exposure to PM10 and changes in DNA methylation and telomere length in cord blood

BACKGROUND

Air pollution exposure in pregnancy can cause molecular level alterations that might influence later disease susceptibility.

OBJECTIVES

We investigated DNA methylation (DNAm) and telomere length (TL) in the cord blood in relation to gestational PM₁₀ exposure and explored potential gestational windows of susceptibility.

METHODS

Cord blood epigenome-wide DNAm (N = 384) and TL (N = 500) were measured in children of the Italian birth cohort Piccolipiù, using the Infinium Methylation EPIC BeadChip and qPCR, respectively. PM₁₀ daily exposure levels, based on maternal residential address, were estimated for different gestational periods using models based on satellite data. Epigenome-wide analysis to identify differentially methylated probes (DMPs) and regions (DMRs) was conducted, followed by a pathway analysis and replication analysis in an second Piccolipiù dataset. Distributed lag models (DLMs) using weekly exposures were used to study the association of PM₁₀ exposure across pregnancy with telomere length, as well as with the DMPs that showed robust associations.

RESULTS

Gestational PM₁₀ exposure was associated with the DNA methylation of more than 250 unique DMPs, most of them identified in early gestation, and 1 DMR. Out of 151 DMPs available in the replication dataset, ten DMPs showed robust associations: eight were associated with exposure during early gestation and 2 with exposure during the whole pregnancy. These exposure windows were supported by the DLM analysis. The PM₁₀ exposure between 15th and 20th gestational week seem to be associated with shorter telomeres at birth, while exposure between 24th and 29th was associated with longer telomeres.

DISCUSSION

The early pregnancy period is a potential critical window during which PM₁₀ exposure can influence cord blood DNA methylation. The results from the TL analysis were consistent with previous findings and merit further exploration in future studies. The study underlines the importance of considering gestational windows outside of the predefined trimesters that may not always overlap with biologically relevant windows of exposure.

Prenatal lead exposure, telomere length in cord blood, and DNA methylation age in the PROGRESS prenatal cohort

BACKGROUND

Lead is a ubiquitous pollutant with deleterious effects on human health and remains a major current public health concern in developing countries. This heavy metal may interfere with nucleic acids via oxidative stress or epigenetic changes that affect biological markers of aging, e.g., telomere length and DNA methylation (DNAm). Telomere shortening associates with biological age in newborns, and DNA methylation at specific CpG sites can be used to calculate "epigenetic clocks".

OBJECTIVE

The aim of this study was to examine the associations of prenatal lead exposures with telomere length and DNA-methylation-based predictors of age in cord blood.

DESIGN

The study included 507 mother-child pairs from the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) study, a birth cohort in Mexico City. Maternal blood (second trimester, third trimester and at delivery) and bone lead levels (one month postpartum) were measured using inductively coupled plasma-mass spectrometry and X-ray fluorescence, respectively. Cord blood leukocyte telomere length was measured using quantitative PCR and apparent age by DNA methylation biomarkers, i.e., Horvath's DNA methylation age and the Knight's predictor of gestational age.

RESULTS

Average maternal age was 28.5 ± 5.5 years, and 51.5% reported low socioeconomic status. Children's mean telomere length was 1.2 ± 1.3 relative units, and mean DNA methylation ages using the Horvath's and Knight's clocks were -2.6 ± 0.1 years and 37.9 ± 1.4 weeks (mean ± SD), respectively. No significant associations were found between maternal blood and bone lead concentrations with telomere length and DNAm age in newborns.

CONCLUSION

We found no associations of prenatal lead exposure with telomere length and DNA methylation age biomarkers.

Prenatal Exposure to Traffic-Related Air Pollution and the DNA Methylation in Cord Blood Cells: MOCEH Study

Particulate matter with a diameter of ≤10 µm (PM₁₀) and nitrogen dioxide (NO₂) affect the DNA methylation in the fetus, but epigenetic studies regarding prenatal exposure to air pollution in Asia are lacking. Therefore, this study aimed to assess whether there is any association between the ambient concentrations of PM₁₀ and NO₂ and CpG methylation in the cord blood DNA by using a Korean birth cohort. The concentrations of the air pollutants were incorporated into the final LUR model by using the maternal address data. The methylation level was determined using HumanMethylationEPIC BeadChip and a linear regression analysis model. A multipollutant model including both PM₁₀ and NO₂ and models with single pollutants were used for each trimester exposure. The number of differentially methylated positions was the largest for midpregnancy exposure in both the single pollutant models and the multipollutant regression analysis. Additionally, gene-set analysis regarding midpregnancy exposure revealed four gene ontology terms (cellular response to staurosporine, positive regulation of cytoskeleton organization, neurotransmitter transport, and execution phase of apoptosis). In conclusion, these findings show an association between prenatal PM₁₀ and NO₂ exposure and DNA methylation in several CpG sites in cord blood cells, especially for midpregnancy exposure.

Prenatal PM2.5 Exposure in Relation to Maternal and Newborn Telomere Length at Delivery

Particulate matter with an aerodynamic diameter of 2.5 μm or less (PM_2.5) is a ubiquitous air pollutant that is increasingly threatening the health of adults and children worldwide. One health impact of elevated PM_2.5 exposure is alterations in telomere length (TL)-protective caps on chromosome ends that shorten with each cell division. Few analyses involve prenatal PM_2.5 exposure, and paired maternal and cord TL measurements. Here, we analyzed the association between average and trimester-specific prenatal PM_2.5 exposure, and maternal and newborn relative leukocyte TL measured at birth among 193 mothers and their newborns enrolled in a New-York-City-based birth cohort. Results indicated an overall negative relationship between prenatal PM_2.5 and maternal TL at delivery, with a significant association observed in the second trimester (β = -0.039, 95% CI: -0.074, -0.003). PM_2.5 exposure in trimester two was also inversely related to cord TL; however, this result did not reach statistical significance (β = -0.037, 95% CI: -0.114, 0.039), and no clear pattern emerged between PM_2.5 and cord TL across the different exposure periods. Our analysis contributes to a limited body of research on ambient air pollution and human telomeres, and emphasizes the need for continued investigation into how PM_2.5 exposure during pregnancy influences maternal and newborn health.

The critical role of epigenetic mechanism in PM2.5-induced cardiovascular diseases

Cardiovascular disease (CVD) has become the leading cause of death worldwide, which seriously threatens human life and health. Epidemiological studies have confirmed the occurrence and development of CVD are closely related to air pollution. In particular, fine particulate matter (PM_2.5) is recognized as an important environmental factor contributing to increased morbidity, mortality and hospitalization rates among adults and children. However, the underlying mechanism by which PM_2.5 promotes CVD development remains unclear. With the development of epigenetics, recent studies have shown that PM_2.5 exposure may induce or aggravate CVD through epigenetic changes. In order to better understand the potential mechanisms, this paper reviews the epigenetic changes of CVD caused by PM_2.5. We summarized the epigenetic mechanisms of PM_2.5 causing cardiovascular pathological damage and functional changes, mainly involving DNA methylation, non-coding RNA, histone modification and chromosome remodeling. It will provide important clues for exploring the biological mechanisms affecting cardiovascular health.

Prenatal Ambient Ultrafine Particle Exposure and Childhood Asthma in the Northeastern United States

Rationale: Ambient ultrafine particles (UFPs; with an aerodynamic diameter < 0.1 μm) may exert greater toxicity than other pollution components because of their enhanced oxidative capacity and ability to translocate systemically. Studies examining associations between prenatal UFP exposure and childhood asthma remain sparse. Objectives: We used daily UFP exposure estimates to identify windows of susceptibility of prenatal UFP exposure related to asthma in children, accounting for sex-specific effects. Methods: Analyses included 376 mother-child dyads followed since pregnancy. Daily UFP exposure during pregnancy was estimated by using a spatiotemporally resolved particle number concentration prediction model. Bayesian distributed lag interaction models were used to identify windows of susceptibility for UFP exposure and examine whether effect estimates varied by sex. Incident asthma was determined at the first report of asthma (3.6 ± 3.2 yr). Covariates included maternal age, education, race, and obesity; child sex; nitrogen dioxide (NO2) and temperature averaged over gestation; and postnatal UFP exposure. Measurements and Main Results: Women were 37.8% Black and 43.9% Hispanic, with 52.9% reporting having an education at the high school level or lower; 18.4% of children developed asthma. The cumulative odds ratio (95% confidence interval) for incident asthma per doubling of the UFP exposure concentration across pregnancy was 4.28 (1.41-15.7), impacting males and females similarly. Bayesian distributed lag interaction models indicated sex differences in the windows of susceptibility, with the highest risk of asthma seen in females exposed to higher UFP concentrations during late pregnancy. Conclusions: Prenatal UFP exposure was associated with asthma development in children, independent of correlated ambient NO2 and temperature. Findings will benefit future research and policy-makers who are considering appropriate regulations to reduce the adverse effects of UFPs on child respiratory health.

Cerebral cortex and blood transcriptome changes in mouse neonates prenatally exposed to air pollution particulate matter

Background

Prenatal exposure to air pollutants is associated with increased risk for neurodevelopmental and neurodegenerative disorders. However, few studies have identified transcriptional changes related to air pollutant exposure.

Methods

RNA sequencing was used to examine transcriptomic changes in blood and cerebral cortex of three male and three female mouse neonates prenatally exposed to traffic-related nano-sized particulate matter (nPM) compared to three male and three female mouse neonates prenatally exposed to control filter air.

Results

We identified 19 nPM-associated differentially expressed genes (nPM-DEGs) in blood and 124 nPM-DEGs in cerebral cortex. The cerebral cortex transcriptional responses to nPM suggested neuroinflammation involvement, including CREB1, BDNF, and IFNγ genes. Both blood and brain tissues showed nPM transcriptional changes related to DNA damage, oxidative stress, and immune responses. Three blood nPM-DEGs showed a canonical correlation of 0.98 with 14 nPM-DEGS in the cerebral cortex, suggesting a convergence of gene expression changes in blood and cerebral cortex. Exploratory sex-stratified analyses suggested a higher number of nPM-DEGs in female cerebral cortex than male cerebral cortex. The sex-stratified analyses identified 2 nPM-DEGs (Rgl2 and Gm37534) shared between blood and cerebral cortex in a sex-dependent manner.

Conclusions

Our findings suggest that prenatal nPM exposure induces transcriptional changes in the cerebral cortex, some of which are also observed in blood. Further research is needed to replicate nPM-induced transcriptional changes with additional biologically relevant time points for brain development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11689-021-09380-3.

Prenatal Household Air Pollution Exposure, Cord Blood Mononuclear Cell Telomere Length and Age Four Blood Pressure: Evidence from a Ghanaian Pregnancy Cohort

Associations between prenatal household air pollution exposure (HAP), newborn telomere length and early childhood blood pressure are unknown. Methods: Pregnant women were randomized to liquefied petroleum gas (LPG) stove, improved biomass stove or control (traditional, open fire cook stove). HAP was measured by personal carbon monoxide (CO) (n = 97) and fine particulate matter (PM_2.5) (n = 60). At birth, cord blood mononuclear cells (CBMCs) were collected for telomere length (TL) analyses. At child age four years, we measured resting blood pressure (BP) (n = 97). We employed multivariable linear regression to determine associations between prenatal HAP and cookstove arm and assessed CBMC relative to TL separately. We then examined associations between CBMC TL and resting BP. Results: Higher prenatal PM_2.5 exposure was associated with reduced TL (β = -4.9% (95% CI -8.6, -0.4), p = 0.03, per 10 ug/m³ increase in PM_2.5). Infants born to mothers randomized to the LPG cookstove had longer TL (β = 55.3% (95% CI 16.2, 109.6), p < 0.01)) compared with control. In all children, shorter TL was associated with higher systolic BP (SBP) (β = 0.35 mmHg (95% CI 0.001, 0.71), p = 0.05, per 10% decrease in TL). Increased prenatal HAP exposure is associated with shorter TL at birth. Shorter TL at birth is associated with higher age four BP, suggesting that TL at birth may be a biomarker of HAP-associated disease risk.

Air pollution and children's health-a review of adverse effects associated with prenatal exposure from fine to ultrafine particulate matter

BACKGROUND

Particulate matter (PM), a major component of ambient air pollution, accounts for a substantial burden of diseases and fatality worldwide. Maternal exposure to PM during pregnancy is particularly harmful to children's health since this is a phase of rapid human growth and development.

METHOD

In this review, we synthesize the scientific evidence on adverse health outcomes in children following prenatal exposure to the smallest toxic components, fine (PM_2.5) and ultrafine (PM_0.1) PM. We highlight the established and emerging findings from epidemiologic studies and experimental models.

RESULTS

Maternal exposure to fine and ultrafine PM directly and indirectly yields numerous adverse birth outcomes and impacts on children's respiratory systems, immune status, brain development, and cardiometabolic health. The biological mechanisms underlying adverse effects include direct placental translocation of ultrafine particles, placental and systemic maternal oxidative stress and inflammation elicited by both fine and ultrafine PM, epigenetic changes, and potential endocrine effects that influence long-term health.

CONCLUSION

Policies to reduce maternal exposure and health consequences in children should be a high priority. PM_2.5 levels are regulated, yet it is recognized that minority and low socioeconomic status groups experience disproportionate exposures. Moreover, PM_0.1 levels are not routinely measured or currently regulated. Consequently, preventive strategies that inform neighborhood/regional planning and clinical/nutritional recommendations are needed to mitigate maternal exposure and ultimately protect children's health.

Symptoms of Prenatal Depression Associated with Shorter Telomeres in Female Placenta

BACKGROUND

Depression is a common mood disorder during pregnancy impacting one in every seven women. Children exposed to prenatal depression are more likely to be born at a low birth weight and develop chronic diseases later in life. A proposed hypothesis for this relationship between early exposure to adversity and poor outcomes is accelerated aging. Telomere length has been used as a biomarker of cellular aging. We used high-resolution telomere length analysis to examine the relationship between placental telomere length distributions and maternal mood symptoms in pregnancy.

METHODS

This study utilised samples from the longitudinal Grown in Wales (GiW) study. Women participating in this study were recruited at their presurgical appointment prior to a term elective caesarean section (ELCS). Women completed the Edinburgh Postnatal Depression Scale (EPDS) and trait subscale of the State-Trait Anxiety Inventory (STAI). Telomere length distributions were generated using single telomere length analysis (STELA) in 109 term placenta (37-42 weeks). Multiple linear regression was performed to examine the relationship between maternally reported symptoms of depression and anxiety at term and mean placental telomere length.

RESULTS

Prenatal depression symptoms were significantly negatively associated with XpYp telomere length in female placenta (B = -0.098, p = 0.026, 95% CI -0.184, -0.012). There was no association between maternal depression symptoms and telomere length in male placenta (B = 0.022, p = 0.586, 95% CI -0.059, 0.103). There was no association with anxiety symptoms and telomere length for either sex.

CONCLUSION

Maternal prenatal depression is associated with sex-specific differences in term placental telomeres. Telomere shortening in female placenta may indicate accelerated placental aging.

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.

Polycyclic aromatic hydrocarbons exposures and telomere length: A cross-sectional study on preschool children

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with shorter telomere length (TL), a marker of ageing at cellular level. However, the available evidence on this association among children is still scarce. We therefore aimed to assess, the relationship between urinary 1-hydroxipayrene (1-OHP), a marker of exposure to PAHs, and relative leukocyte TL (LTL) in children at preschool age. Our study was based on 200 children enrolled from 27 randomly-selected kindergartens in the city of Sabzevar, Iran (2017). 1-OHP levels in the participants' urine samples were measured using solid phase extraction (SPE) method and high-performance liquid chromatography (HPLC). Moreover, real-time PCR was used to measure the LTL in the participants' blood samples. Linear mixed effects models, controlled for relevant covariates, were applied to investigate the association of 1-OHP concentration and LTL. The median (interquartile range (IQR)) of relative LTL and urinary 1-OHP were 0.83 (0.7) and 257 (375.5) ng/L, respectively. In the fully adjusted model, an IQR increase in urinary 1-OHP was related to -0.05 (95% confidence interval (CI): 0.09, -0.01, P-value = 0.02) decrease in relative LTL. This association was similar among boys and girls; however, we observed indications for a stronger association for those children whose parents had university education. Our study suggested an inverse relationship between urinary 1-OHP and LTL in children at preschool age. However, further longitudinal research with repeated measures of PAHs and LTL are needed to confirm these findings.

Identifying sensitive windows of airborne lead exposure associated with behavioral outcomes at age 12

Despite the precipitous decline of airborne lead concentrations following the removal of lead in gasoline, lead is still detectable in ambient air in most urban areas. Few studies, however, have examined the health effects of contemporary airborne lead concentrations in children.

METHODS

We estimated monthly air lead exposure among 263 children (Cincinnati Childhood Allergy and Air Pollution Study; Cincinnati, OH; 2001-2005) using temporally scaled predictions from a validated land use model and assessed neurobehavioral outcomes at age 12 years using the parent-completed Behavioral Assessment System for Children, 2nd edition. We used distributed lag models to estimate the effect of airborne lead exposure on behavioral outcomes while adjusting for potential confounding by maternal education, community-level deprivation, blood lead concentrations, greenspace, and traffic related air pollution.

RESULTS

We identified sensitive windows during mid- and late childhood for increased anxiety and atypicality scores, whereas sensitive windows for increased aggression and attention problems were identified immediately following birth. The strongest effect was at age 12, where a 1 ng/m3 increase in airborne lead exposure was associated with a 3.1-point (95% confidence interval: 0.4, 5.7) increase in anxiety scores. No sensitive windows were identified for depression, somatization, conduct problems, hyperactivity, or withdrawal behaviors.

CONCLUSIONS

We observed associations between exposure to airborne lead concentrations and poor behavioral outcomes at concentrations 10 times lower than the National Ambient Air Quality Standards set by the US Environmental Protection Agency.

Associations of Pre- and Postnatal Air Pollution Exposures with Child Blood Pressure and Modification by Maternal Nutrition: A Prospective Study in the CANDLE Cohort

BACKGROUND

Limited data suggest air pollution exposures may contribute to pediatric high blood pressure (HBP), a known predictor of adult cardiovascular diseases.

METHODS

We investigated this association in the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) study, a sociodemographically diverse pregnancy cohort in the southern United States with participants enrolled from 2006 to 2011. We included 822 mother-child dyads with available address histories and a valid child blood pressure measurement at 4-6 y. Systolic (SBP) and diastolic blood pressures (DBP) were converted to age-, sex-, and height-specific percentiles for normal-weight U.S. children. HBP was classified based on SBP or DBP ≥ 90 th percentile. Nitrogen dioxide (NO 2 ) and particulate matter ≤ 2.5 μ m in aerodynamic diameter (PM 2.5 ) estimates in both pre- and postnatal windows were obtained from annual national models and spatiotemporal models, respectively. We fit multivariate Linear and Poisson regressions and explored multiplicative joint effects with maternal nutrition, child sex, and maternal race using interaction terms.

RESULTS

Mean PM 2.5 and NO 2 in the prenatal period were 10.8 [standard deviation (SD): 0.9] μ g / m 3 and 10.0 (SD: 2.4) ppb, respectively, and 9.9 (SD: 0.6) μ g / m 3 and 8.8 (SD: 1.9) ppb from birth to the 4-y-old birthday. On average, SBP percentile increased by 14.6 (95% CI: 4.6, 24.6), and DBP percentile increased by 8.7 (95% CI: 1.4, 15.9) with each 2 - μ g / m 3 increase in second-trimester PM 2.5 . PM 2.5 averaged over the prenatal period was only significantly associated with higher DBP percentiles [β = 11.6 (95% CI: 2.9, 20.2)]. Positive associations of second-trimester PM 2.5 with SBP and DBP percentiles were stronger in children with maternal folate concentrations in the lowest quartile (p interaction = 0.05 and 0.07, respectively) and associations with DBP percentiles were stronger in female children (p interaction = 0.05). We did not detect significant association of NO 2 , road proximity, and postnatal PM 2.5 with any outcomes.

CONCLUSIONS

The findings suggest that higher prenatal PM 2.5 exposure, particularly in the second trimester, is associated with elevated early childhood blood pressure. This adverse association could be modified by pregnancy folate concentrations. https://doi.org/10.1289/EHP7486.

Exposure to ambient air pollution in the first 1000 days of life and alterations in the DNA methylome and telomere length in children: A systematic review

BACKGROUND

Exposure to air pollution during the first 1000 days of life (from conception to the 2nd year of life) might be of particular relevance for long-term child health. Changes in molecular markers such as DNA methylation and telomere length could underlie the association between air pollution exposure and pollution-related diseases as well as serve as biomarkers for past exposure. The objective of this systematic review was to assess the association between air pollution exposure during pregnancy and the first two years of life and changes in DNA methylation or telomere length in children.

METHODS

PubMed was searched in October 2020 by using terms relative to ambient air pollution exposure, DNA methylation, telomere length and the population of interest: mother/child dyads and children. Screening and selection of the articles was completed independently by two reviewers. Thirty-two articles matched our criteria. The majority of the articles focused on gestational air pollution exposure and measured DNA methylation/telomere length in newborn cord blood or placental tissue, to study global, candidate-gene or epigenome-wide methylation patterns and/or telomere length. The number of studies in children was limited.

RESULTS

Ambient air pollution exposure during pregnancy was associated with global loss of methylation in newborn cord blood and placenta, indicating the beginning of the pregnancy as a potential period of susceptibility. Candidate gene and epigenome-wide association studies provided evidence that gestational exposure to air pollutants can lead to locus-specific changes in methylation, in newborn cord blood and placenta, particularly in genes involved in cellular responses to oxidative stress, mitochondrial function, inflammation, growth and early life development. Telomere length shortening in newborns and children was seen in relation to gestational pollutant exposure.

CONCLUSIONS

Ambient air pollution during pregnancy is associated with changes in both global and locus-specific DNA methylation and with telomere length shortening. Future studies need to test the robustness of the association across different populations, to explore potential windows of vulnerability and assess the role of the methylation and telomere length as mediators in the association between early exposure to ambient air pollutants and specific childhood health outcomes.

Child buccal telomere length and mitochondrial DNA content as biomolecular markers of ageing in association with air pollution

BACKGROUND

Pro-inflammatory conditions such as air pollution might induce biological ageing. However, the available evidence on such an impact in children is still very scarce. We studied in primary schoolchildren the association of ambient residential air pollution exposure with telomere length (TL) and mitochondrial DNA content (mtDNAc), two important targets of the core axis of ageing.

METHODS

Between 2012 and 2014, buccal TL and mtDNAc were repeatedly assessed using qPCR in 197 Belgian primary schoolchildren (mean age 10.3 years) as part of the COGNAC study. At the child's residence, recent (week), sub-chronic (month) and chronic (year) exposure to nitrogen dioxide (NO₂), particulate matter ≤ 2.5 µm (PM_2.5) and black carbon (BC) were estimated using a high resolution spatiotemporal model. A mixed-effects model with school and subject as random effect was used while adjusting for a priori chosen covariates.

RESULTS

An interquartile range (IQR) increment (1.9 µg/m³) in chronic PM_2.5 exposure was associated with a 8.9% (95% CI: -15.4 to -1.9%) shorter TL. In contrast to PM_2.5, chronic exposure to BC and NO₂ was not associated with TL but recent exposure to BC and NO₂ showed significant inverse associations with TL: an IQR increment in recent exposure to BC (0.9 µg/m³) and NO₂ (10.2 µg/m³) was associated with a 6.2% (95% CI: -10.6 to -1.6%) and 6.4% (95% CI: -11.8 to -0.7%) shorter TL, respectively. Finally, an IQR increment in chronic PM_2.5 exposure was associated with a 12.7% (95% CI: -21.7 to -2.6%) lower mtDNAc. However, no significant associations were seen for NO₂ and BC or for other exposure windows.

CONCLUSION

Chronic exposure to PM_2.5 below the EU threshold was associated with child's shorter buccal TL and lower mtDNAc, while traffic-related pollutants (BC and NO₂) showed recent effects on telomere biology. Our data add to the literature on air pollution-induced effects of TL and mtDNAc, two measures part of the core axis of cellular ageing, from early life onwards.

Role of maternal nutrition and oxidative stress in placental telomere attrition in women with preeclampsia

Background:Maternal nutrition influences the growth and development of the fetus and influences pregnancy outcome. We have earlier demonstrated altered maternal nutrition and increased oxidative stress in women with preeclampsia. Oxidative stress is known to be associated with reduced telomere length and short telomere aggregates. Increased telomere attrition leads to increased cellular senescence and tissue ageing. Methods:The present review focuses on the role of maternal nutrition and oxidative stress in telomere attrition in preeclampsia. Results and Conclusion:Future studies need to examine the association between maternal nutritional status in early pregnancy, oxidative stress and telomere attrition in preeclampsia.

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.

Telomere length in newborns is associated with exposure to low levels of air pollution during pregnancy

Telomere length (TL) is a biomarker of biological aging that may be affected by prenatal exposure to air pollution. The aim of this study was to assess the association between prenatal exposure to air pollution and TL in maternal blood cells (leukocytes), placenta and umbilical cord blood cells, sampled immediately after birth in 296 Danish mother-child pairs from a birth cohort. Exposure data was obtained using the high-resolution and spatial-temporal air pollution modeling system DEHM-UBM-AirGIS for PM_2.5, PM₁₀, SO₂, NH₄⁺, black carbon (BC), organic carbon (OC), CO, O₃, NO₂, and NO_x at residential and occupational addresses of the participating women for the full duration of the pregnancy. The association between prenatal exposure to air pollutants and TL was investigated using distributed lag models. There were significant and positive associations between TL in umbilical cord blood cells and prenatal exposure to BC, OC, NO₂, NO_x, CO, and O₃ during the second trimester. TL in umbilical cord blood was significantly and inversely associated with prenatal exposure to PM_2.5, BC, OC, SO₂, NH₄⁺, CO and NO₂ during the third trimester. There were similar inverse associations between TL from umbilical cord blood cells and air pollution exposure at the residential and occupational addresses. There were weaker or no associations between air pollution exposure and TL in placenta tissue and maternal blood cells. In conclusion, both the second and third trimesters of pregnancy are shown to be sensitive windows of exposure to air pollution affecting fetal TL.

Association between prenatal immune phenotyping and cord blood leukocyte telomere length in the PRISM pregnancy cohort

BACKGROUND

Environmental exposures including air pollutants, toxic metals, and psychosocial stress have been associated with shorter telomere length (TL) in newborns. These exposures have in turn been linked to an enhanced inflammatory immune response. Increased inflammation during pregnancy may be a central biological pathway linking environmental factors with reduced TL at birth. Approaches that more comprehensively characterize the prenatal inflammatory milieu rather than targeting specific individual cytokines in relation to newborn TL may better elucidate inflammatory mechanisms.

METHODS

Analyses included 129 mother-child dyads enrolled in the PRogramming of Intergenerational Stress Mechanisms (PRISM) pregnancy cohort. We measured 92 inflammation related proteins during pregnancy in maternal serum using the Olink protein array and quantified cord blood relative leukocyte TL (rLTL) via qPCR. We leveraged a tree-based machine learning algorithm to select the most important inflammatory related proteins jointly associated with rLTL. We then evaluated the combined association between the selected proteins with rLTL using Bayesian Weighted Quantile Sum (BWQS) Regression. Analyses were adjusted for gestational week of serum collection, maternal race/ethnicity, age, and education, and fetal sex. We evaluated major biological function of the identified proteins by using the UniProtKB, a centralized repository of curated functional information.

RESULTS

Three proteins were negatively and linearly associated with rLTL (CASP8 β: -0.22 p = 0.008, BNGF β: -0.43 p = 0.033, TRANCE β: 0.38 p = 0.004). Results from BWQS regression showed a significant overall decrease in rLTL (β: -0.26 95%CrI: -0.43, -0.07) per quartile increase of the mixture, with CASP8 contributing the greatest weight (CASP8 50%; BNGF 27%, and TRANCE 23%). The identified proteins were involved in the regulation of apoptotic processes and cell proliferation.

CONCLUSIONS

This proteomics approach identifies novel maternal prenatal inflammatory protein biomarkers associated with shortened rLTL in newborns.

Telomere length: how the length makes a difference

Telomerase is perceived as an immortality enzyme that might provide longevity to cells and whole organisms. Importantly, it is generally inactive in most somatic cells of healthy, adult men. Consequently, its substrates, i.e. telomeres, get shorter in most human cells with time. Noteworthy, cell life limitation due to telomere attrition during cell divisions, may not be as bad as it looks since longer cell life means longer exposition to harmful factors. Consequently, telomere length (attrition rate) becomes a factor that is responsible for inducing the signaling that leads to the elimination of cells that lived long enough to acquire severe damage. It seems that telomere length that depends on many different factors (including telomerase activity but also genetic factors, a hormonal profile that reflects sex, etc.) might become a useful marker of aging and exposition to stress. Thus in the current paper, we review the factors that affect telomere length in human cells focusing on sex that all together with different environmental and hormonal regulations as well as parental aspect affect telomere attrition rate. We also raise some limitations in the assessment of telomere length that hinders a trustworthy meta-analysis that might lead to acknowledgment of the real value of this parameter.

Prenatal particulate air pollution and newborn telomere length: Effect modification by maternal antioxidant intakes and infant sex

BACKGROUND

Evidence links gestational exposure to particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5) with changes in leukocyte telomere length in cord blood with some studies showing sex-specific effects. PM_2.5 exposure in utero increases oxidative stress, which can impact telomere biology. Thus, maternal antioxidant intakes may also modify the particulate air pollution effects.

METHODS

We examined associations among prenatal PM_2.5 exposure and newborn relative leukocyte telomere length (rLTL), and the modifying effects of maternal antioxidant intake and infant sex. We estimated daily PM_2.5 exposures over gestation using a validated spatiotemporally resolved satellite-based model. Maternal dietary and supplemental antioxidant intakes over the prior three months were ascertained during the second trimester using the modified Block98 food frequency questionnaire; high and low antioxidant intakes were categorized based on a median split. We employed Bayesian distributed lag interaction models (BDLIMs) to identify both sensitive windows of exposure and cumulative effect estimates for prenatal PM_2.5 exposure on newborn rLTL, and to examine effect modification by maternal antioxidant intakes. A 3-way interaction between PM_2.5, maternal antioxidant intake and infant sex was also explored.

RESULTS

For the main effect of PM_2.5, BDLIMs identified a sensitive window at 12-20 weeks gestation for the association between increased prenatal PM_2.5 exposure and shorter newborn rLTL and a cumulative effect of PM_2.5 over gestation on newborn telomere length [cumulative effect estimate (CEE) = -0.29 (95% CI -0.49 to -0.10) per 1μg/m³ increase in PM_2.5]. In models examining maternal antioxidant intake effects, BDLIMs found that children born to mothers reporting low antioxidant intakes were most vulnerable [CEE of low maternal antioxidant intake = -0.31 (95% CI -0.55 to -0.06) vs high maternal antioxidant intake = -0.07 (95% CI -0.34 to 0.17) per 1μg/m³ increase in PM_2.5]. In exploratory models examining effect modification by both maternal antioxidant intakes and infant sex, the cumulative effect remained significant only in boys whose mothers reported low antioxidant intakes [CEE = -0.38 (95% CI -0.80 to -0.004)]; no sensitive windows were identified in any group.

CONCLUSIONS

Prenatal PM_2.5 exposure in mid-gestation was associated with reduced infant telomere length. Higher maternal antioxidant intakes mitigated these effects.

Placental and Cord Blood Telomere Length in Relation to Maternal Nutritional Status

BACKGROUND

The uterine environment may be important for the chromosomal telomere length (TL) at birth, which, in turn, influences disease susceptibility throughout life. However, little is known about the importance of specific nutritional factors.

OBJECTIVES

We assessed the impact of multiple maternal nutritional factors on TL in placenta and cord blood.

METHODS

In a population-based mother-child cohort in northwestern Argentina, we measured maternal weight, BMI, body fat percentage (BFP), and several nutrients [selenium, magnesium, calcium, zinc, manganese, iodine, vitamin B-12, folate, 25-hydroxycholecalciferol (25(OH)D3)], hemoglobin, and homocysteine in maternal whole blood, serum, plasma, or urine during pregnancy (mean gestational week 27). We measured the relative TL (rTL) in placenta (n = 99) and cord blood (n = 98) at delivery by real-time PCR. Associations were evaluated by multivariable-adjusted linear regression.

RESULTS

The women's prepregnancy BMI (kg/m2; mean ± SD: 23.7 ± 4.1), body weight (55.4 ± 9.9 kg), and BFP (29.9 ± 5.5%), but not height (153 ± 5.3 cm), were inversely associated with placental rTL (P < 0.01 for all), with ∼0.5 SD shorter rTL for an IQR increase in prepregnancy body weight, BMI, or BFP. Also, impedance-based BFP, but not lean body mass, in the third trimester was associated with shorter placental rTL. In addition, serum vitamin B-12 (232 ± 96 pmol/L) in pregnancy (P = 0.038), but not folate or homocysteine, was associated with shorter placental rTL (0.2 SD for an IQR increase). In contrast, plasma 25(OH)D3 (46 ± 15 nmol/L) was positively associated with placental rTL (P < 0.01), which increased by 0.4 SD for an IQR increase in 25(OH)D3. No clear associations of the studied maternal nutritional factors were found with cord blood rTL.

CONCLUSIONS

Maternal BMI, BFP, and vitamin B-12 were inversely associated, whereas 25(OH)D3 was positively associated, with placental TL. No association was observed with cord blood TL. Future studies should elucidate the role of placental TL for child health.

Telomere erosion as a placental clock: From placental pathologies to adverse pregnancy outcomes

The placenta provides nutritional and gas exchange between fetus and mother. Early in pregnancy, placental trophoblasts proliferate rapidly and invade aggressively. As pregnancy progresses, placental cells begin to age. Indeed, pregnancy itself has a tightly regulated duration, determined in large part by placental lifespan. Late in pregnancy, placental cells reach a senescent apoptotic state, activated by a number of intrinsic and extrinsic factors, including oxidative stress (OS), and DNA damage. Pregnancy complications, stillbirths and neonatal deaths have been related to OS and abnormal placental aging. Telomeres, the protective nucleoprotein structures at the ends of linear chromosomes, shorten both from cell replication and from exposure to OS. When telomeres become critically short they trigger cell cycle arrest and eventually cell death. Telomere attrition thus provide an intrinsic mechanism to explain tissue senescence and aging. Mounting evidence suggests that senescence of placental and fetal membrane cells results from telomere attrition. We review the studies that have addressed the role of telomere length (TL) in placentas from normal and complicated pregnancies, including pre-eclampsia, intrauterine growth restriction, gestational diabetes, and stillbirth. To date studies have uncovered associations between TL and a number of obstetrical complications. Future research is needed to determine whether these associations are causative, i.e. whether these clinical conditions result from telomere dysfunction, and whether particular features of telomeres, e.g. mean or shortest length, etc. could serve as clinically useful biomarkers of placental health.

Identifying critical windows of prenatal particulate matter (PM2.5) exposure and early childhood blood pressure

BACKGROUND

Exposure to air pollution is associated with increased blood pressure (BP) in adults and children. Some evidence suggests that air pollution exposure during the prenatal period may contribute to adverse cardiorenal health later in life. Here we apply a distributed lag model (DLM) approach to identify critical windows that may underlie the association between prenatal particulate matter ≤ 2.5 μm in diameter (PM_2.5) exposure and children's BP at ages 4-6 years.

METHODS

Participants included 537 mother-child dyads enrolled in the Programming Research in Obesity, GRowth Environment, and Social Stress (PROGRESS) longitudinal birth cohort study based in Mexico City. Prenatal daily PM_2.5 exposure was estimated using a validated satellite-based spatio-temporal model and BP was measured using the automated Spacelabs system with a sized cuff. We used distributed lag models (DLMs) to examine associations between daily PM_2.5 exposure and systolic and diastolic BP (SBP and DBP), adjusting for child's age, sex and BMI, as well as maternal education, preeclampsia and indoor smoking report during the second and third trimester, seasonality and average postnatal year 1 PM_2.5 exposure.

RESULTS

We found that PM_2.5 exposure between weeks 11-32 of gestation (days 80-226) was significantly associated with children's increased SBP. Similarly, PM_2.5 exposure between weeks 9-25 of gestation (days 63-176) was significantly associated with increased DBP. To place this into context, a constant 10 μg/m³ increase in PM_2.5 sustained throughout this critical window would predict a cumulative increase of 2.6 mmHg (CI: 0.5, 4.6) in SBP and 0.88 mmHg (CI: 0.1, 1.6) in DBP at ages 4-6 years. In a stratified analysis by sex, this association persisted in boys but not in girls.

CONCLUSIONS

Second and third trimester PM_2.5 exposure may increase children's BP in early life. Further work investigating PM_2.5 exposure with BP trajectories later in childhood will be important to understanding cardiorenal trajectories that may predict adult disease. Our results underscore the importance of reducing air pollution exposure among susceptible populations, including pregnant women.

Air pollution and placental mitochondrial DNA copy number: Mechanistic insights and epidemiological challenges

During embryogenesis and embryo implantation, the copy number of mtDNA is elaborately regulated to meet the cellular demand for division, growth and differentiation. With large numbers of mitochondria for energy production, placental cells possess strong endocrine functionalities and capacities for efficient signaling communication. Recently, several environmental epidemiological studies have shown an association between mitochondrial DNA copy number, adverse birth outcomes and maternal exposure to air pollution, which has shed light on the possible effect of pollutants on placental molecular events. Because the mtDNA replication is thought to be a direct drive of mtDNA change, we tried to highlight the essential factors involved in the process of mtDNA replication. Then we traced the mtDNA change in the formation of placenta during embryogenesis, and evaluated the importance of mitochondrial genome maintenance during gestation. The possible mechanism from the epidemiological and experimental studies were reviewed and summarized, and recommendations were proposed for future studies to improve the precision of the estimated difference. The issue will be well-understood if the integrated profiles, such as familial genetic tendency, maternal genetic information, identification of mitochondrial DNA copy number in each placental cell type, and total personal exposure assessment, are considered in the future study.