Hazardous air pollutants and telomere length in the Sister Study

Application of the Key Characteristics Framework to Identify Potential Breast Carcinogens Using Publicly Available in Vivo, in Vitro, and in Silico Data

BACKGROUND

Chemicals that induce mammary tumors in rodents or activate estrogen or progesterone signaling are likely to increase breast cancer (BC) risk. Identifying chemicals with these activities can prompt steps to protect human health.

OBJECTIVES

We compiled data on rodent tumors, endocrine activity, and genotoxicity to assess the key characteristics (KCs) of rodent mammary carcinogens (MCs), and to identify other chemicals that exhibit these effects and may therefore increase BC risk.

METHODS

Using authoritative databases, including International Agency for Research on Cancer (IARC) Monographs and the US Environmental Protection's (EPA) ToxCast, we selected chemicals that induce mammary tumors in rodents, stimulate estradiol or progesterone synthesis, or activate the estrogen receptor (ER) in vitro. We classified these chemicals by their genotoxicity and strength of endocrine activity and calculated the overrepresentation (enrichment) of these KCs among MCs. Finally, we evaluated whether these KCs predict whether a chemical is likely to induce mammary tumors.

RESULTS

We identified 279 MCs and an additional 642 chemicals that stimulate estrogen or progesterone signaling. MCs were significantly enriched for steroidogenicity, ER agonism, and genotoxicity, supporting the use of these KCs to predict whether a chemical is likely to induce rodent mammary tumors and, by inference, increase BC risk. More MCs were steroidogens than ER agonists, and many increased both estradiol and progesterone. Enrichment among MCs was greater for strong endocrine activity vs. weak or inactive, with a significant trend.

DISCUSSION

We identified hundreds of compounds that have biological activities that could increase BC risk and demonstrated that these activities are enriched among MCs. We argue that many of these should not be considered low hazard without investigating their ability to affect the breast, and chemicals with the strongest evidence can be targeted for exposure reduction. We describe ways to strengthen hazard identification, including improved assessments for mammary effects, developing assays for more KCs, and more comprehensive chemical testing. https://doi.org/10.1289/EHP13233.

Individual Differences in Relative Telomere Length in Mentally Healthy Subjects: The Effect of TERT Gene Polymorphism and Urban Residency

The changes in the telomere length caused by the terminal underreplication in the existing literature are related to depressive disorders. However, the use of the telomere length as a biomarker of depressive states is ambiguous, which is due to the effect of various environmental factors on both the psychoemotional state and cellular aging of an organism. In order to identify the possible use of the relative telomere length (RTL) measured in peripheral blood leukocytes as a biomarker of enhanced liability to depression prior to the clinical symptoms, as well as to determine the link between telomere length, sociodemographic factors, allelic variants of the genes involved in the regulation of telomere elongation, and depression level, the association analysis of reverse transcriptase (TERT rs7726159), telomerase RNA component (TERC rs1317082), and the CST complex encoding protein (OBFC1 rs2487999) gene polymorphisms was performed with RTL and depression level in mentally healthy individuals (N = 1065) aged 18-25 years. Together with genetic variants, the examined regression models included various sociodemographic parameters as predictors. As a result of statistical analysis, we failed to observe the association between RTL and individual differences in depression level in the studied sample. Nevertheless, multiple regression analysis allowed us to construct a statistically significant model of individual variance in RTL (P = 4.3е-4; r ² = 0.018), which included rs7726159 in the TERT gene (P = 0.020; β = 0.078) and such environmental predictors as age (P = 0.001; β = -0.027) and place of residence in childhood (urban/rural area) (P = 0.048; β = 0.063). The data obtained confirm the involvement of TERT gene variants and age in telomere length in mentally healthy individuals aged 18-25 years and indicate a negative effect of urban residency on telomere length shortening, which reflects the cellular aging of an organism.

Leukocyte telomere length and obesity in children and adolescents: A systematic review and meta-analysis

Background: Several studies have revealed the negative effects of adiposity on telomere length shortening. However, the results of the studies assessing the negative relationship between obesity and leukocyte telomere length (LTL) are not consistent. This systematic review and meta-analysis are aimed to pool the results of articles assessing the relationship between obesity and LTL among children and adolescents. Methods: To retrieve the related studies, four online databases including PubMed, Embase, ProQuest, and Scopus were searched until May 2022. Observational studies evaluating the relationship between obesity and LTL among apparently healthy children and adolescents (aged ≤18 years) were included in the study. We considered the studies that had reported a mean ± standard deviation of LTL. The random-effects model was used to assess the pooled weighted mean difference (WMD) and a 95% confidence interval (CI). Results: The search yielded seven studies from an initial 3,403 records identified. According to the results of seven articles with 4,546 participants, obesity was associated with LTL shortening among children and adolescents (WMD = -0.081; 95% CI: -0.137 to -0.026; p = 0.004; I2 = 99.9%). Also, no publication bias was observed. According to the results of subgrouping, significant results were only attributed to the studies conducted in Europe, with high quality scores, among overweight and obese adolescents, with a baseline LTL lower than 1, and performed in community-based school settings. Also, according to the subgrouping and meta-regression results, the obesity definition criteria and baseline LTL were the possible sources of between-study heterogeneity. Conclusion: We observed shorter LTL among overweight and obese children and adolescents. To obtain more reliable results, further longitudinal prospective studies with large sample sizes and more consistent and accurate definitions of obesity are required.

Personal exposure to benzene, toluene, ethylbenzene, and xylenes (BTEXs) mixture and telomere length: a cross-sectional study of the general US adult population

BACKGROUND

Benzene, Toluene, Ethylbenzene, and Xylenes (BTEXs) are a group of aromatic air pollutants from fossil fuels. There is no research on associations of the BTEXs mixture with telomere length (TL), a marker of cellular aging, in the general population.

METHODS

We analyzed a subsample of 549 US adults aged 20-59 years from the National Health and Nutrition Examination Survey 1999-2000. BTEXs samples were collected by passive exposure badges worn by participants for 48-72 h. Levels of BTEXs were measured with gas chromatography/mass spectrometry. Leukocyte TL was measured with qPCR. We used Bayesian Kernel Machine Regression (BKMR) to examine the effect of the BTEXs mixture on TL adjusting for potential confounders. Analyses were stratified by tobacco smoking status (serum cotinine≥10 ng/mL vs. <10 ng/mL).

RESULTS

Levels of personal exposure to BTEXs were detectable in most participants and were relatively higher in the 150 smokers than in the 399 nonsmokers. The BTEXs were moderately or strongly intercorrelated (0.5 < r ≤ 0.9, P < 0.05). All chemicals had weak, inverse correlations with TL (-0.1<r < 0, P > 0.05). In BKMR models among the nonsmokers, the BTEXs mixture was significantly inversely associated with TL at a low range of the BTEXs (20th-65th percentile) but was not associated with TL at a higher range (>65th percentile). Also, we found a U-shape association of benzene and a positive association of ethylbenzene with TL independent of other BTEXs. Among smokers, neither the BTEXs mixture nor any individual BTEXs were significantly associated with TL.

CONCLUSION

Within a low-to-middle range, exposure to the BTEXs mixture may be associated with shorter telomere length in the general nonsmoking population.

Telomeres, aging and reproduction

PURPOSE OF REVIEW

Women's fertility decay starts at the mid 30 s. However, the current delay of childbearing leads to ovarian aging and the need of assisted reproduction technologies (ART). Telomere biology is one of the main pathways involved in organismal aging. Thus, this review will focus on the knowledge acquired during the last 2 years about the telomere pathway and its influence on female fertility and the consequences for the newborn.

RECENT FINDINGS

New research on telomere biology reaffirms the relationship of telomere attrition and female infertility. Shorter maternal telomeres, which could be aggravated by external factors, underly premature ovarian aging and other complications including preeclampsia, preterm birth and idiopathic pregnancy loss. Finally, the telomere length of the fetus or the newborn is also affected by external factors, such as stress and nutrition.

SUMMARY

Recent evidence shows that telomeres are implicated in most processes related to female fertility, embryo development and the newborn's health. Thus, telomere length and telomerase activity may be good biomarkers for early detection of ovarian and pregnancy failures, opening the possibility to use telomere therapies to try to solve the infertility situation.

Vitamin D Deficiency and Risk of Metabolic Syndrome in Aging Men

The elderly population is rapidly increasing; hence, the disability due to age-related diseases has become an important socioeconomic burden. Amongst age-related diseases cardiovascular ones (CVD) have a huge impact on morbidity and mortality and are associated with metabolic syndrome (MetS). Several studies investigated the role of hypovitaminosis D in the pathogenesis of MetS and of CVD, this review unravels the relationship between aging/senescence, vitamin D, gender, and pathogenesis of MetS.