Association of residential greenness, air pollution with adverse birth outcomes: Results from 61,762 mother­neonatal pairs in project ELEFANT (2011-2021).

BACKGROUND: Emerging evidence has demonstrated the benefits of greenness exposure on human health, while conflicts remain unsolved in issue of adverse birth outcomes. METHODS: Utilizing data from project ELEFANT spanning the years 2011 to 2021, we assessed residential greenness using the NDVI from MODIS data and residential PM2.5 exposure level from CHAP data. Our primary concerns were PTD, LBW, LGA, and SGA. Cox proportional hazard regression model was used to examine the association of residential greenness and air pollution exposure with risk of adverse birth outcomes. We performed mediation and modification effect analyses between greenness and air pollutant. RESULTS: We identified 61,762 mother­neonatal pairs in final analysis. For per 10 µg/m3 increase in PM2.5 concentration during entire pregnancy was associated with 19.8 % and 20.7 % increased risk of PTD and LGA. In contrast, we identified that an 0.1 unit increment in NDVI were associated with 24 %, 43 %, 26.5 %, and 39.5 % lower risk for PTD, LBW, LGA, and SGA, respectively. According to mediation analysis, NDVI mediated 7.70 % and 7.89 % of the associations between PM2.5 and PTD and LGA. Residential greenness could reduce the risk of PTD among mothers under 35 years old, living in rural areas, primigravidae and primiparity.. CONCLUSIONS: In summary, our results highlighted the potential of residential greenness to mitigate the risk of adverse birth outcomes, while also pointing to the adverse impact of PM2.5 on increased risk of multiple adverse birth outcomes (PTD and LGA). The significant mediation effect of NDVI emphasizes its potential as an important protective factor of PM2.5 exposure. Additionally, the identification of susceptible subgroups can inform targeted interventions to reduce adverse birth outcomes related to air pollution and lack of green spaces. Further research and understanding of these associations can contribute to better public health strategies aimed at promoting healthier pregnancies and birth outcomes.

Association between diesel exhaust exposure and mitochondrial DNA methylation.

OBJECTIVES: Diesel exhaust is an established human carcinogen, however the mechanisms by which it leads to cancer development are not fully understood. Mitochondrial dysfunction is an established contributor to carcinogenesis. Recent studies have improved our understanding of the role played by epigenetic modifications in the mitochondrial genome on tumorigenesis. In this study, we aim to evaluate the association between diesel engine exhaust (DEE) exposure with mitochondrial DNA (mtDNA) methylation levels in workers exposed to DEE. METHODS: The study population consisted of 53 male workers employed at a diesel engine manufacturing facility in Northern China who were routinely exposed to diesel exhaust in their occupational setting, as well as 55 unexposed male control workers from other unrelated factories in the same geographic area. Exposure to DEE, elemental carbon, organic carbon, and particulate matter (PM2.5) were assessed. mtDNA methylation for CpG sites (CpGs) from seven mitochondrial genes (D-Loop, MT-RNR1, MT-CO2, MT-CO3, MT-ATP6, MT-ATP8, MT-ND5) was measured in blood samples. Linear regression models were used to estimate the associations between DEE, elemental carbon, organic carbon and PM2.5 exposures with mtDNA methylation levels, adjusting for potential confounders. RESULTS: DEE exposure was associated with decreased MT-ATP6 (difference = -35.6%, P-value = 0.019) and MT-ATP8 methylation (difference = -30%, P-value = 0.029) compared to unexposed controls. Exposures to elemental carbon, organic carbon, and PM2.5 were also significantly and inversely associated with methylation in MT-ATP6 and MT-ATP8 genes (all P-values < 0.05). CONCLUSIONS: Our findings suggest that DEE exposure perturbs mtDNA methylation, which may be of importance for tumorigenesis.

Genomic targets and selective inhibition of DNA methyltransferase isoforms.

BACKGROUND: DNA methylation in the human genome is established and maintained by DNA methyltransferases (DNMTs). DNMT isoforms show differential expression by cell lineage and during development, but much remains to be elucidated about their shared and unique genomic targets. RESULTS: We examined changes in the epigenome following overexpression of 13 DNMT isoforms in HEK293T cells. We observed increased methylation (Δß > 0.2) at 43,405 CpG sites, with expression of DNMT3A2, DNMTΔ3B4 and DNMTΔ3B2 associated with the greatest impact. De novo methylation occurred primarily within open sea regions and at loci with intermediate methylation levels (ß: 0.2-0.6). 53% of differentially methylated loci showed specificity towards a single DNMT subfamily, primarily DNMTΔ3B and DNMT3A and 39% towards a single isoform. These loci were significantly enriched for pathways related to neuronal development (DNMTΔ3B4), calcium homeostasis (DNMTΔ3B3) and ion transport (DNMT3L). Repetitive elements did not display differential sensitivity to overexpressed DNMTs, but hypermethylation of Alu elements was associated with their evolutionary age following overexpression of DNMT3A2, DNMT3B1, DNMT3B2 and DNMT3L. Differential methylation (Δß > 0.1) was observed at 121 of the 353 loci associated with the Horvath 'epigenetic clock' model of ageing, with 51 showing isoform specificity, and was associated with reduction of epigenetic age by 5-15 years following overexpression of seven isoforms. Finally, we demonstrate the potential for dietary constituents to modify epigenetic marks through isoform-specific inhibition of methylation activity. CONCLUSIONS: Our results provide insight into regions of the genome methylated uniquely by specific DNMT isoforms and demonstrate the potential for dietary intervention to modify the epigenome.

Association between mitochondrial DNA methylation and internal exposure to polycyclic aromatic hydrocarbons (PAHs), nitrated-PAHs (NPAHs) and oxygenated-PAHs (OPAHs) in young adults from Tianjin, China.

Polycyclic aromatic hydrocarbons (PAHs), nitrated-PAHs (NPAHs) and oxygenated-PAHs (OPAHs) are environmental pollutants with adverse effects on human health. The correlation between the concentrations of PAHs, NPAHs and OPAHs in human plasma and the methylation level of mitochondrial DNA (mtDNA) was investigated using data from 110 plasma samples collected in Tianjin, China. The median concentrations of PAHs, NPAHs and OPAHs were 16.0 (IQR: 14.4-20.7) ng/mL, 82.2 (IQR: 63.1-97.6) ng/mL and 49.6 (IQR: 28.6-53.8) ng/mL, and the mean proportions were 13.4%, 56.5% and 30.1%, respectively. Bisulfite-PCR pyrosequencing was used to measure the methylation level of MT-CO1 and tRNA-Leu. The methylation levels of two mitochondrial genes (MT-CO1, tRNA-Leu) including four CpG sites (MT-CO1-P1, MT-CO1-P2, tRNA-Leu-P1 and tRNA-Leu-P2) were 0.67% ± 1.38%, 13.54% ± 2.59%, 7.23% ± 5.35% and 1.64% ± 2.94%, respectively. To the best of our knowledge, this is the first time that significant correlations were found between PAHs and their derivatives exposure and mtDNA methylation levels.

The exposure levels and health risk assessment of antibiotics in urine and its association with platelet mitochondrial DNA methylation in adults from Tianjin, China: A preliminary study.

There has been extensive research on antibiotics exposure in adults by biomonitoring, but the biological mechanisms and potential risks to human health remain limited. In this study, 102 adults aged 26-44 years in Tianjin were studied and 23 common antibiotics in urine were analyzed by Liquid chromatography-mass spectrometry (LC-MS). All antibiotics were detected in urine, with an overall detection frequency of 40.4% (the detection frequencies of phenothiazines, quinolones, sulfonamides, tetracyclines, and chloramphenicol were 77%, 54%, 24%, 28%, and 49%, respectively.). Ofloxacin and enrofloxacin had the highest detection frequencies (85% and 81%), with median concentrations of 0.26 (IQR: 0.05-1.36) and 0.09 (IQR: 0.03-0.14) ng/mL, respectively. Based on health risk assessment, the predicted estimated daily exposures (EDEs) ranged from 0 µg/kg/day to 13.98 µg/kg/day. The hazard quotient (HQ) values of all the antibiotics except ofloxacin and ciprofloxacin were bellow one, which are considered safe. For all blood samples, the mitochondrial DNA (mtDNA) methylation levels in the MT-ATP6 (ranging between 3.86% and 34.18%) were slightly higher than MT-ATP8 and MT-ND5 (ranging between 0.57% and 9.32%, 1.08% and 19.62%, respectively). Furthermore, mtDNA methylation from MT-ATP6, MT-ATP8 and MT-ND5 were measured by bisulfite-PCR pyrosequencing. The association (P < 0.05) was found between mtDNA methylation level (MT-ATP8 and MT-ND5) and individual antibiotics including chlorpromazine, ciprofloxacin, enrofloxacin, norfloxacin, pefloxacin, sulfaquinoxaline, sulfachloropyridazine, chloramphenicol, and thiamphenicol, indicating that persistent exposure to low-dose multiple antibiotics may affect the mtDNA methylation level and in turn pose health risks.

Associations of adverse pregnancy outcomes with high ambient air pollution exposure: Results from the Project ELEFANT.

BACKGROUND: Investigations on the potential effects of high air pollution exposure before pregnancy on adverse pregnancy outcomes are limited, and it is unknown whether air quality standards looser than that set by World Health Organization (WHO) still can provide sufficient protection pregnant women from adverse pregnancy outcomes. OBJECTIVES: To evaluate the potential effects of high ambient air pollution around pregnancy on preterm birth (PTB) and low birth weight (LBW), and assess the risk of PTB and LBW associated with air pollutants with reference to different air quality standards of WHO and China. METHODS: Our study leveraged 10,960 pregnant women from the Project ELEFANT. Daily average particulate matter with an aerodynamic diameter of ≤2.5 µm (PM2.5) and ≤10 µm (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO) and ozone (O3) concentrations were collected based on Chinese Air Quality Reanalysis datasets. Hazard ratios (HR) of PTB and LBW were estimated for maternal PM2.5, PM10, NO2, SO2, CO and O3 exposures and related proportions of days with daily average air pollution concentrations exceeding air quality standards of WHO and China around pregnancy using Cox proportional hazards regression models with adjustment for potential confounders. RESULTS: Ambient PM2.5, PM10, NO2, SO2 and CO exposure during the before pregnancy and pregnancy period were both significantly and positively associated with increased risk of PTB, PTB subtypes and LBW. A 10% increase in proportion of days with daily average PM2.5 exceeding 25 µg/m3 over the entire pregnancy was most apparently associated with risk of PTB (HR, 12.66; 95% CI, 8.20-19.53) and LBW (HR, 17.42; 95% CI, 6.88-44.10) among all PM2.5 proportion variables based on different air quality standards. CONCLUSION: Air quality standards of WHO are necessary to be implemented to control for risks of adverse pregnancy outcomes associated with ambient air pollution in areas with high air pollution levels.

Analysis of retrotransposon subfamily DNA methylation reveals novel early epigenetic changes in chronic lymphocytic leukemia.

Retrotransposons such as LINE-1 and Alu comprise >25% of the human genome. While global hypomethylation of these elements has been widely reported in solid tumours, their epigenetic dysregulation is yet to be characterised in chronic lymphocytic leukaemia, and there has been scant consideration of their evolutionary history that mediates sensitivity to hypomethylation. Here, we developed an approach for locus- and evolutionary subfamily-specific analysis of retrotransposons using the Illumina Infinium Human Methylation 450K microarray platform, which we applied to publicly-available datasets from chronic lymphocytic leukaemia and other haematological malignancies. We identified 9,797 microarray probes mapping to 117 LINE-1 subfamilies and 13,130 mapping to 37 Alu subfamilies. Of these, 10,782 were differentially methylated (PFDR<0.05) in chronic lymphocytic leukaemia patients (n=139) compared with healthy individuals (n=14), with enrichment at enhancers (p=0.002). Differential methylation was associated with evolutionary age of LINE-1 (r2=0.31, p=0.003) and Alu (r2=0.74, p=0.002) elements, with greater hypomethylation of older subfamilies (L1M, AluJ). Locus-specific hypomethylation was associated with differential expression of proximal genes, including DCLK2, HK1, ILRUN, TANK, TBCD, TNFRSF1B and TXNRD2, with higher expression of DCLK2 and TNFRSF1B associated with reduced patient survival. Hypomethylation at nine loci was highly frequent in chronic lymphocytic leukaemia (>90% patients) but not observed in healthy individuals or other leukaemias, and was detectable in blood samples taken prior to chronic lymphocytic leukaemia diagnosis in 9 of 82 individuals from the Melbourne Collaborative Cohort Study. Our results demonstrate differential methylation of retrotransposons in chronic lymphocytic leukaemia by their evolutionary heritage that modulates expression of proximal genes.

Elevated serum mitochondrial DNA in females and lack of altered platelet mitochondrial methylation in patients with Parkinson´s disease.

Purpose: Mitochondrial dysfunction has long been considered in the pathogenesis of Parkinson's disease (PD). This is evident from the presence of mitochondrial DNA deletions in substantia nigra neurons and respiratory chain abnormalities in the skeletal muscle of PD patients. However, the contributing factors that potentially cause oxidative stress in PD are still elusive. To a certain extent, the identification of acquired changes in circulating mitochondrial DNA (mtDNA) content in blood samples may mirror the mitochondrial (dys-) function. Therefore, herein, we investigated the mtDNA concentrations in serum and cerebrospinal fluid (CSF) of PD patients.Materials and methods: We performed quantitative analysis (qPCR) at two mitochondrial regions (D-Loop; ATPase6) and evaluated the platelet mtDNA methylation levels (MT-TL1 ,MT-CO1, MT-CO2 and MT-CO3) by bisulfite-PCR pyrosequencing.Results: Our quantitative analysis at two mitochondrial regions (D-Loop; ATPase6) revealed an increase in mtDNA serum concentrations in PD females compared to healthy females. Of particular interest, these altered concentrations were restricted to females serum only. Thus, in males as well as CSF of PD patients no increase was detected. Additionally, mtDNA methylation in platelets isolated from the plasma of PD patients showed no altered methylation levels in the mitochondrial MT-TL1 and MT-CO1 regions. Besides, a complete lack of platelet mtDNA methylation was observed at MT-CO2 and MT-CO3 mitochondrial sites.Conclusions: Taken together, we found an increased mtDNA serum concentration exclusively in PD females. As of yet, it is unclear whether this might reflect specific changes or characteristics of female PD pathobiology. However, in context to the ongoing debate about mtDNA methylation, we could show that the mitochondrial epigenome does harbor detectable CpG methylation sites in platelets-derived DNA.

Mitochondrial DNA methylation in placental tissue: a proof of concept study by means of prenatal environmental stressors.

While previous studies have demonstrated that prenatal exposure to environmental stressors is associated with mitochondrial DNA (mtDNA) methylation, more recent investigations are questioning the accuracy of the methylation assessment and its biological relevance. In this study, we investigated placental mtDNA methylation while accounting for methodological issues such as nuclear contamination, bisulphite conversion, and PCR bias. From the ENVIRONAGE birth cohort, we selected three groups of participants (n = 20/group). One group with mothers who smoked during pregnancy (average 13.2 cig/day), one group with high air pollutant exposure (PM2.5: 16.0 ± 1.4 µg/m3, black carbon: 1.8 ± 0.3 µg/m3) and one control group (non-smokers, PM2.5: 10.6 ± 1.7 µg/m3, black carbon: 0.9 ± 0.1 µg/m3) with low air pollutant exposure. DNA methylation levels were quantified in two regions of the displacement loop control region (D-loop and LDLR2) by bisulphite pyrosequencing. Additionally, we measured DNA methylation on nuclear genes involved in mitochondrial maintenance (PINK1, DNA2, and POLG1) and assessed mtDNA content using qPCR. Absolute D-loop methylation levels were higher for mothers that smoked extensively (+0.36%, 95% CI: 0.06% to 0.66%), and for mothers that were highly exposed to air pollutants (+0.47%, 95% CI: 0.20% to 0.73%). The relevance of our findings is further supported, as D-loop methylation levels were correlated with placental mtDNA content (r = -0.40, p = 0.002) and associated with birth weight (-106.98 g, 95% CI: -209.60 g to -4.36 g for an IQR increase in D-loop methylation). Most notably, our data demonstrates relevant levels of mtDNA methylation in placenta tissue, with significant associations between prenatal exposure to environmental stressors and D-loop methylation.

Environmental epitranscriptomics.

Chemical modifications of RNA molecules have gained increasing attention since evidence emerged for their substantive roles in a range of biological processes, such as the stability and translation of mRNA transcripts. More than 150 modifications have been identified in different organisms to date, collectively known as the 'epitranscriptome', with 6-methyladenosine (m6A), 5-methylcytidine (m5C), pseudouridine and N1-methyladenosine (m1A) the most extensively investigated. Although we are just beginning to elucidate the roles of these modifications in cellular functions, there is already evidence for their dysregulation in diseases such as cancer and neurodevelopmental disorders. There is currently more limited knowledge regarding how environmental exposures affect the epitranscriptome and how this may mediate disease risk, but evidence is beginning to emerge. Here, we review the current evidence for the impact of environmental exposures such as benzo[a]pyrene, bisphenol A, pesticides, metals and nanoparticles upon RNA modifications and the expression of their 'writers' (methyl transferases), 'erasers' (demethylases) and 'readers'. We discuss future directions of the field and identify areas of particular promise and consider the technical challenges that are faced.

Prenatal PM2.5 exposure and the risk of adverse births outcomes: Results from Project ELEFANT.

BACKGROUND: Studies investigating the impact of fine particulate matter (PM2.5) exposure during pregnancy upon adverse birth outcomes have primarily been performed in Western nations with low ambient PM2.5 levels. We examined associations between high levels of PM2.5 exposure during pregnancy and risk of adverse birth outcomes by timing and level of exposure in a Chinese population. METHODS: We analysed data from 10,738 live births within the Project ELEFANT study based in Tianjin, China. Personal mean daily PM2.5 exposures were estimated using data from 25 local monitoring sites across the city, used to compute the days exceeding 50, 100, 150, 200 and 250 µg/m3. Relative risk of pre-term birth (<37 weeks) and low birthweight (<2500 g) were estimated by generalized additive distributed lag models, adjusted for maternal age, sex, region, paternal smoking, parity, maternal occupation, season, temperature and dew point. RESULTS: A dose-response was exhibited for PM2.5 exposure and relative risk (RR) of adverse birth outcomes, with exposure in the second and third trimesters of pregnancy associated with greatest risk of adverse birth outcomes. The RRs of pre-term birth with exposures of >50, >150 and > 250 µg/m3 PM2.5 in the third trimester were 1.09 (95%CI: 1.03-1.16), 1.30 (1.09-1.54) and 2.73 (2.03-3.66) respectively. For low birthweight, exposures of >50, >150 and > 250 µg/m3 PM2.5 in the third trimester were associated with RRs of 0.99 (0.88-1.11), 1.37 (1.04-1.81) and 3.03 (1.75-5.23) respectively. CONCLUSIONS: Exposure to high levels of PM2.5 from the second trimester onwards was most strongly associated with increased risk of pre-term birth and low birthweight, with a dose-response relationship. Our data demonstrates the need to account for both level and timing of exposure in analysis of PM2.5-associated birth outcomes.

DNA methylation patterns of LINE-1 and Alu for pre-symptomatic dementia in type 2 diabetes.

The identification of early markers of dementia is important for higher-risk populations such as those with type 2 diabetes (T2D). Retrotransposons, including long interspersed nuclear element 1 (LINE-1) and Alu, comprise ~40% of the human genome. Although dysregulation of these retrotransposons can induce aberrant gene regulation and genomic instability, their role in the development of pre-symptomatic dementia (PSD) among T2D patients is unknown. Here, we examined locus-specific changes in LINE-1 and Alu methylation in PSD and the potential to offset these changes via supplementation with folate and vitamin B12. We interrogated DNA methylation patterns corresponding to 22,352 probes for LINE-1 and Alu elements using publicly-available Illumina Infinium 450K methylation datasets from i) an 18-month prospective study in 28 T2D patients (GSE62003) and ii) an intervention study in which 44 individuals were supplemented with folic acid (400 µg/day) and vitamin B12 (500 µg/day) over two years (GSE74548). We identified 714 differentially methylated positions (DMP) mapping to retrotransposons in T2D patients who developed PSD in comparison to those who did not (PFDR < 0.05), comprised of 2.4% (228 probes) of all LINE-1 probes and 3.8% (486 probes) of all Alu probes. These loci were enriched in genes with functions related to Alzheimer's disease and cognitive decline, including GNB5, GNG7 and PKN3 (p < 0.05). In older individuals supplemented with folate/vitamin B12, 85 (11.9%) PSD retrotransposon loci showed significant changes in methylation (p < 0.05): participants with the MTHFR CC genotype predominantly showed hypermethylation at these loci, while hypomethylation was observed more frequently in those with the TT genotype. In T2D patients, LINE-1 and Alu elements are differentially methylated in PSD in a locus-specific manner and may offer clinical utility in monitoring risk of dementia. Further work is required to examine the potential for dietary supplementation in lowering the risk of PSD.

Platelet mitochondrial DNA methylation predicts future cardiovascular outcome in adults with overweight and obesity.

BACKGROUND: The association between obesity and cardiovascular disease (CVD) is proven, but why some adults with obesity develop CVD while others remain disease-free is poorly understood. Here, we investigated whether mitochondrial DNA (mtDNA) methylation in platelets is altered prior to CVD development in a population of adults with overweight and obesity. METHODS: We devised a nested case-control study of 200 adults with overweight or obesity who were CVD-free at baseline, of whom 84 developed CVD within 5 years, while 116 remained CVD-free. Platelet mtDNA was isolated from plasma samples at baseline, and mtDNA methylation was quantified in mitochondrially encoded cytochrome-C-oxidase I (MT-CO1; nt6797 and nt6807), II (MT-CO2; nt8113 and nt8117), and III (MT-CO3; nt9444 and nt9449); tRNA leucine 1 (MT-TL1; nt3247 and nt3254); D-loop (nt16383); tRNA phenylalanine (MT-TF; nt624); and light-strand-origin-of-replication (MT-OLR; nt5737, nt5740, and nt5743) by bisulfite-pyrosequencing. Logistic regression was used to estimate the contribution of mtDNA methylation to future CVD risk. ROC curve analysis was used to identify the optimal mtDNA methylation threshold for future CVD risk prediction. A model was generated incorporating methylation at three loci (score 0, 1, or 2 according to 0, 1, or 2-3 hypermethylated loci, respectively), adjusted for potential confounders, such as diastolic and systolic blood pressure, fasting blood glucose, and cholesterol ratio. mtDNA methylation at MT-CO1 nt6807 (OR = 1.08, 95% CI 1.02-1.16; P = 0.014), MT-CO3 nt9444 (OR = 1.22, 95% CI 1.02-1.46, P = 0.042), and MT-TL1 nt3254 (OR = 1.30, 95% CI 1.05-1.61, P = 0.008) was higher at baseline in those who developed CVD by follow-up, compared with those who remained CVD-free. Combined use of the three loci significantly enhanced risk prediction, with hazard ratios of 1.38 (95% CI 0.68-2.78) and 2.68 (95% CI 1.41-5.08) for individuals with score 1 or 2, respectively (P = 0.003). Methylation at these sites was independent of conventional CVD risk factors, including inflammation markers, fasting blood glucose concentration, and blood pressure. CONCLUSIONS: Methylations of MT-CO1, MT-CO3, and MT-TL1 are, together, strong predictors of future CVD incidence. Since methylation of these mtDNA domains was independent of conventional CVD risk factors, these markers may represent a novel intrinsic predictor of CVD risk in adults with overweight and obesity.

Exposure to environmental toxicants reduces global N6-methyladenosine RNA methylation and alters expression of RNA methylation modulator genes.

The epitranscriptome comprises more than 100 forms of RNA modifications. Of these, N6-methyladenosine (m6A) is the most abundantform of RNA methylation, with roles in modulating mRNA transcript processing and regulation. The aims of the study weretoexamine changes inm6A RNA methylation in A549 lung epithelial cells in response to environmental toxicants, anddifferential gene expression of m6A modulator genes ('readers', 'writers' and 'erasers') in human subjects exposed toparticulate matter (PM) and in lung cancer tissueusing publicly-available microarray datasets. Global m6A methylation levelsweremeasured in total RNA after exposuretotwo carcinogens (PM and sodium arsenite) for 24- and 48-h, and totwo endocrine disruptors (bisphenol A and vinclozolin)for 24-h.Global m6A methylation level significantly decreased with exposure to >62 µg/mlPM, >1 µM sodium arsenite, >1  µM bisphenol A (BPA), and0.1  µM vinclozolin. In an analysis of a published dataset derived from a population study, we observed that m6A writers (METTL3 and WTAP), erasers (FTO and ALKBH5) and readers (HNRPC) showed significantly higher expression among participants in the high-PM2.5exposure group compared to those in the low-exposure control group (all p < 0.05). Further, the m6A writer METTL3shows reduced expression in lung tumors in comparison to normal lung epithelia (p < 0.0001). Our findings reveal that m6A RNA methylation can be modified by exposure to environmental toxicants, and exposure to particulate matter is associated with differential expression level of m6A RNA methylation modification machinery.

Psychosocial stress is associated with benign breast disease in young Chinese women: results from Project ELEFANT.

PURPOSE: Psychosocial stress, including bereavement and work-related stress, is associated with the risk of breast cancer. However, it is unknown whether it may also be linked with increased risk of benign breast disease (BBD). METHODS: Our study leveraged 61,907 women aged 17-55 years old from the Project ELEFANT study. BBD was diagnosed by clinician. Self-reported data on psychosocial stress over a 10-year period was retrospectively collected from questionnaires and categorised by cause (work, social and economic) and severity (none, low and high). Odd ratios (ORs) for the development of BBD were estimated using logistic regression. The model was adjusted for age, BMI, TSH levels, smoking, alcohol consumption, family history, age of menarche, oral contraceptive usage, education and occupation. RESULTS: Within our study, 8% (4,914) of participants were diagnosed with BBD. Work-related stress [OR 1.57, 95% confidence interval (CI) 1.46-1.69] and financial stress (OR 1.34, 95% CI 1.24-1.44) were significantly associated with BBD incidence, with a smaller but still significant association with social stress (OR 1.11, 95% CI 1.01-1.21). The associations remained significant after exclusion of participants with first- and second-degree family history of breast disease. The presence of multiple forms of stress did not synergistically increase risk. The neutrophil-lymphocyte ratio (NLR), a marker of systemic inflammation and prognostic marker for breast cancer, was not associated with BBD. CONCLUSIONS: Psychosocial stress, particularly work-related and financial stress, is associated with increased risk of benign breast disease among young Chinese women.

Obesity as an effect modifier of the association between menstrual abnormalities and hypertension in young adult women: Results from Project ELEFANT.

BACKGROUND: The menstrual cycle is regulated by reproductive hormones such as estrogen which has been implicated in the pathogenesis of hypertension and is associated with obesity. However, to date there has scant study of hypertension in relation to menstrual characteristics and abnormalities. We hypothesize that adverse menstrual characteristics are associated with an increase the prevalence of hypertension and that this relationship is exacerbated by obesity. METHODS: Our study leverages 178,205 healthy female participants (mean age = 29) in a population-based cross-sectional study in Tianjin, China. Menstrual characteristics including menstrual cycle length and regularity, menstrual bleeding length, menstrual blood loss and dysmenorrhea were assessed by self-reported questionnaires, and hypertension was diagnosed by physician. Multiple logistic regression models were used to assess the relationships between menstrual characteristics and hypertension. RESULTS: Normal length menstrual cycle (OR = 1.21, 95% CI: 1.03-1.41), oligomenorrhea (OR = 1.54, 95% CI: 1.12-2.07), irregular cycle (OR = 1.54, 95% CI: 1.22-1.93), and light menstrual blood loss (OR = 1.36, 95% CI: 1.06-1.72) were associated with hypertension among women who are overweight or obese, but not among women who are normal weight. Longer menstrual bleeding duration (OR = 1.44, 95% CI: 1.24-1.67) and dysmenorrhea were associated with increased prevalence of hypertension (OR = 1.20, 95% CI: 1.14-1.41) in all young women. CONCLUSIONS: The prevalence of hypertension is higher among women with menstrual abnormalities, and this association is modified by overweight and obesity.

Age at menarche and prevention of hypertension through lifestyle in young Chinese adult women: result from project ELEFANT.

BACKGROUND: Early and late age at menarche are associated with risk of hypertension, but little is known whether modifiable lifestyle can reduce this risk. METHODS: Our study leverages 60,135 healthy young Chinese women from the Environmental and LifEstyle FActors iN metabolic health throughout life-course Trajectories (ELEFANT) study. Menarche age and lifestyle factors were assessed by self-reported questionnaires and hypertension was diagnosed by physicians. We estimated the odds ratios (ORs) of hypertension associated with menarche age using multivariable logistic regression. We further investigated whether modifiable lifestyles (body mass index, BMI; psychological stress; passive smoking; and imbalanced diet) increased risk in joint analyses. RESULTS: The association between age at menarche and hypertension was U-shaped, with age ≤ 12 at menarche giving the highest OR (1.46, 95% confidence interval [CI], 1.27-1.69) and ≥ 16 the second highest (OR = 1.36, 95% CI = 1.15-1.62). Simultaneous analysis of lifestyle risk factors and age of menarche showed that having one or more modifiable risk factors increased the menarche age-hypertension association. The risk of hypertension among participants with menarche age ≤ 12 decreased from OR 13.21 (95% CI = 5.17-29.36) with four high-risk lifestyle factors to 12.36 (95% CI = 9.51-16.05) with three high-risk factors, 5.24 (95% CI = 4.11-6.69) with two, and 2.76 (95% CI = 2.09-3.60) with one, in comparison to individuals with no high-risk lifestyle factors and menarche age 14. CONCLUSIONS: Our results suggest that modification of lifestyle, including maintenance of normal weight and a balanced diet, are associated with substantially reduce the risk of hypertension in high-risk individuals. Early and late age at menarche are risk factors for the development of hypertension in Western populations, and there is limited evidence that this is also true of Chinese populations. Targeted prevention of hypertension in vulnerable populations would be highly beneficial in efforts to reduce the incidence of cardiovascular disease, but it is not currently known whether lifestyle intervention could reduce hypertension risk. In this study, we analysed the risk of hypertension by age at menarche and four modifiable lifestyle factors (BMI, diet, psychological stress, and smoking tobacco) in a cohort of 60,135 young adult Chinese women (mean age 29). We identified that early and late age at menarche are associated with increased risk of hypertension in young Chinese women. There was joint effects between age at menarche and lifestyles on hypertension only participants with age at menarche ≤12 and being overweight or obese. Modification of lifestyle, including maintenance of normal weight and a balanced diet, can substantially reduce the risk of hypertension in high-risk individuals. In conclusion, our study has revealed that early and late menarche age are associated with the development of hypertension in young Chinese women, and that this risk is modified by healthy lifestyle traits.

Dietary Intervention Modifies DNA Methylation Age Assessed by the Epigenetic Clock.

SCOPE: Alterations in DNA methylation patterns are correlated with aging, environmental exposures, and disease pathophysiology; the possibility of reverting or preventing these processes through dietary intervention is gaining momentum. In particular, methyl donors that provide S-adenosyl-methionine for one-carbon metabolism and polyphenols such as flavanols that inhibit the activity of DNA methyltransferases (DNMTs) can be key modifiers of epigenetic patterns. METHODS AND RESULTS: DNA methylation patterns are assessed in publicly available Illumina Infinium 450K methylation datasets from intervention studies with either folic acid + vitamin B12 (GSE74548) or monomeric and oligomeric flavanols (MOF) (GSE54690) in 44 and 13 participants, respectively. Global DNA methylation levels are increased in unmethylated regions such as CpG islands and shores following folic acid + vitamin B12 supplementation and decreased in highly methylated regions, including shelves and open-seas, following intervention with MOF. After supplementation with folic acid + vitamin B12, epigenetic age, estimated by the Horvath "epigenetic clock" model, is reduced in women with the MTHFR 677CC genotype. CONCLUSIONS: The effects of supplementation with folic acid + vitamin B12 and MOF on DNA methylation age are dependent upon gender and MTHFR genotype. Additionally, the findings demonstrate the potential for these dietary factors to modulate global DNA methylation profiles.

Aberrant promoter methylation in genes related to hematopoietic malignancy in workers exposed to a VOC mixture.

Occupational exposure to volatile organic compounds (VOCs) may cause hematopoietic malignancy, either by single exposure to benzene or possibly due to a concomitant exposure to several VOCs. Since oxidative stress, inflammation and DNA repair pathways are closely involved in cancer development, the effect of VOC exposure on expression of proteins involved in these pathways has been studied, but epigenetic changes have not been well described. Here, DNA methylation status following occupational exposure to a VOC mixture was assessed by bisulfite sequencing of the promoter regions of seven genes involved in the mentioned pathways. Peripheral blood samples and individual-level VOC exposure data were obtained from healthy leather shoe factory workers (LS, n=40) and gas station attendants (GS, n=36), as well as a reference group of university employees (C, n=66). Exposure levels for acetone, ethylbenzene, methyl ethyl ketone, n-hexane, toluene and xylene were higher in LS (p<0.001); benzene and methyl acetate levels were higher in GS (p<0.001). TOP2A, SOD1, and TNF-α promoter methylation status was increased in LS (p<0.05). In LS, we also found significant correlations between GSTP1 promoter methylation and both iNOS (r=0.37, p=0.008) and COX-2 (r=-0.38, p=0.007) methylation. In exposed groups, ethylbenzene exposure levels showed a significant correlation with TOP2A methylation (ß=0.33). Our results show early, toxic effects at the epigenetic level caused by occupational exposure to high levels of a VOC mixture. These subcellular modifications may represent the initial mechanism of toxicity leading to hematopoietic malignancy, possibly due to a synergistic, hematotoxic effect of VOC mixtures.