Placental epigenetic gestational aging in relation to maternal sociodemographic factors and smoking among infants born extremely preterm: a descriptive study.

Social determinants of health (SDoH) are defined as the conditions in which people are born, grow, live, work, and age. The distribution of these conditions is influenced by underlying structural factors and may be linked to adverse pregnancy outcomes through epigenetic modifications of gestational tissues. A promising modification is epigenetic gestational age (eGA), which captures 'biological' age at birth. Measuring eGA in placenta, an organ critical for foetal development, may provide information about how SDoH 'get under the skin' during pregnancy to influence birth outcomes and ethnic/racial disparities. We examined relationships of placental eGA with sociodemographic factors, smoking, and two key clinical outcomes: Apgar scores and NICU length of stay. Using the Robust Placental Clock, we estimated eGA for placental samples from the Extremely Low Gestational Age Newborns cohort (N = 408). Regression modelling revealed smoking during pregnancy was associated with placental eGA acceleration (i.e., eGA higher than chronologic gestational age). This association differed by maternal race: among infants born to mothers racialized as Black, we observed greater eGA acceleration (+0.89 week, 95% CI: 0.38, 1.40) as compared to those racialized as white (+0.27 week, 95% CI: -0.06, 0.59). Placental eGA acceleration was also correlated with shorter NICU lengths of stay, but only among infants born to mothers racialized as Black (-0.08 d/week-eGA, 95% CI: -0.12, -0.05). Together, these observed associations suggest that interpretations of epigenetic gestational aging may be tissue-specific.

Placental genomics mediates genetic associations with complex health traits and disease.

As the master regulator in utero, the placenta is core to the Developmental Origins of Health and Disease (DOHaD) hypothesis but is historically understudied. To identify placental gene-trait associations (GTAs) across the life course, we perform distal mediator-enriched transcriptome-wide association studies (TWAS) for 40 traits, integrating placental multi-omics from the Extremely Low Gestational Age Newborn Study. At [Formula: see text], we detect 248 GTAs, mostly for neonatal and metabolic traits, across 176 genes, enriched for cell growth and immunological pathways. In aggregate, genetic effects mediated by placental expression significantly explain 4 early-life traits but no later-in-life traits. 89 GTAs show significant mediation through distal genetic variants, identifying hypotheses for distal regulation of GTAs. Investigation of one hypothesis in human placenta-derived choriocarcinoma cells reveal that knockdown of mediator gene EPS15 upregulates predicted targets SPATA13 and FAM214A, both associated with waist-hip ratio in TWAS, and multiple genes involved in metabolic pathways. These results suggest profound health impacts of placental genomic regulation in developmental programming across the life course.

Comparing the Predictivity of Human Placental Gene, microRNA, and CpG Methylation Signatures in Relation to Perinatal Outcomes.

Molecular signatures are being increasingly integrated into predictive biology applications. However, there are limited studies comparing the overall predictivity of transcriptomic versus epigenomic signatures in relation to perinatal outcomes. This study set out to evaluate mRNA and microRNA (miRNA) expression and cytosine-guanine dinucleotide (CpG) methylation signatures in human placental tissues and relate these to perinatal outcomes known to influence maternal/fetal health; namely, birth weight, placenta weight, placental damage, and placental inflammation. The following hypotheses were tested: (1) different molecular signatures will demonstrate varying levels of predictivity towards perinatal outcomes, and (2) these signatures will show disruptions from an example exposure (ie, cadmium) known to elicit perinatal toxicity. Multi-omic placental profiles from 390 infants in the Extremely Low Gestational Age Newborns cohort were used to develop molecular signatures that predict each perinatal outcome. Epigenomic signatures (ie, miRNA and CpG methylation) consistently demonstrated the highest levels of predictivity, with model performance metrics including R2 (predicted vs observed) values of 0.36-0.57 for continuous outcomes and balanced accuracy values of 0.49-0.77 for categorical outcomes. Top-ranking predictors included miRNAs involved in injury and inflammation. To demonstrate the utility of these predictive signatures in screening of potentially harmful exogenous insults, top-ranking miRNA predictors were analyzed in a separate pregnancy cohort and related to cadmium. Key predictive miRNAs demonstrated altered expression in association with cadmium exposure, including miR-210, known to impact placental cell growth, blood vessel development, and fetal weight. These findings inform future predictive biology applications, where additional benefit will be gained by including epigenetic markers.

Identifying the Transcriptional Response of Cancer and Inflammation-Related Genes in Lung Cells in Relation to Ambient Air Chemical Mixtures in Houston, Texas.

Atmospheric pollution represents a complex mixture of air chemicals that continually interact and transform, making it difficult to accurately evaluate associated toxicity responses representative of real-world exposure. This study leveraged data from a previously published article and reevaluated lung cell transcriptional response induced by outdoor atmospheric pollution mixtures using field-based exposure conditions in the industrialized Houston Ship Channel. The tested hypothesis was that individual and co-occurring chemicals in the atmosphere relate to altered expression of critical genes involved in inflammation and cancer-related processes in lung cells. Human lung cells were exposed at an air-liquid interface to ambient air mixtures for 4 h, with experiments replicated across 5 days. Real-time monitoring of primary and secondary gas-phase pollutants, as well as other atmospheric conditions, was simultaneously conducted. Transcriptional analysis of exposed cells identified critical genes showing differential expression associated with both individual and chemical mixtures. The individual pollutant identified with the largest amount of associated transcriptional response was benzene. Tumor necrosis factor (TNF) and interferon regulatory factor 1 (IRFN1) were identified as key upstream transcription factor regulators of the cellular response to benzene. This study is among the first to measure lung cell transcriptional responses in relation to real-world, gas-phase air mixtures.

Isoprene-Derived Secondary Organic Aerosol Induces the Expression of MicroRNAs Associated with Inflammatory/Oxidative Stress Response in Lung Cells.

Exposure to fine particulate matter (PM2.5), of which secondary organic aerosol (SOA) is a major constituent, is linked to adverse health outcomes, including cardiovascular disease, lung cancer, and preterm birth. Atmospheric oxidation of isoprene, the most abundant nonmethane hydrocarbon emitted into Earth's atmosphere primarily from vegetation, contributes to SOA formation. Isoprene-derived SOA has previously been found to alter inflammatory/oxidative stress genes. MicroRNAs (miRNAs) are epigenetic regulators that serve as post-transcriptional modifiers and key mediators of gene expression. To assess whether isoprene-derived SOA alters miRNA expression, BEAS-2B lung cells were exposed to laboratory-generated isoprene-derived SOA constituents derived from the acid-driven multiphase chemistry of authentic methacrylic acid epoxide (MAE) or isomeric isoprene epoxydiols (IEPOX) with acidic sulfate aerosol particles. These IEPOX- and MAE-derived SOA constituents have been shown to be measured in large quantities within PM2.5 collected from isoprene-rich areas affected by acidic sulfate aerosol particles derived from human activities. A total of 29 miRNAs were identified as differentially expressed when exposed to IEPOX-derived SOA and 2 when exposed to MAE-derived SOA, a number of which are inflammatory/oxidative stress associated. These results suggest that miRNAs may modulate the inflammatory/oxidative stress response to SOA exposure, thereby advancing the understanding of airway cell epigenetic response to SOA.

Placental CpG Methylation of Inflammation, Angiogenic, and Neurotrophic Genes and Retinopathy of Prematurity.

Purpose: Extremely preterm infants are at increased risk for retinopathy of prematurity (ROP). We previously identified several inflammatory proteins that were expressed early in life and are associated with an increased risk of ROP and several angiogenic and neurotrophic growth factors in the neonatal systemic circulation that are associated with a lower risk of ROP. In this paper, we report the results of a set of analyses designed to test the hypothesis that placental CpG methylation levels of 12 inflammation-, angiogenic-, and neurotrophic-associated genes predict the occurrence of prethreshold ROP in extremely preterm newborns. Methods: We used placental CpG methylation data from 395 newborns from the Extremely Low Gestational Age Newborns study. Results: Multivariable regression models revealed that placental DNA methylation of 16 CpG sites representing 8 genes were associated with prethreshold ROP. Specifically, CpG methylation in the serum amyloid A SAA1 and SAA2, brain-derived neurotrophic factor (BDNF), myeloperoxidase (MPO), C-reactive protein (CRP), angiopoietin 1 (ANGPT1), and tumor necrosis factor receptor superfamily member 1B (TNFRSF1B) genes was associated with a lower risk of prethreshold ROP. Conversely, CpG methylation at three probes within tumor necrosis factor receptor superfamily member 1A (TNFRSF1A) and in two alternative probes within the BDNF and ANGPT1 genes was associated with an increased risk of ROP. Conclusions: CpG methylation may be a useful marker for improving ROP prediction, opening the opportunity for early intervention to lessen disease severity.

Disinfection Byproducts Bind Human Estrogen Receptor-α.

Disinfection byproducts are formed during most drinking water treatment and presently number >800, some of which are implicated in human health outcomes including bladder cancer and infertility, with unknown mechanisms of action. In particular, it is not yet understood whether these compounds can disrupt the estrogen-signaling pathway through binding to the human estrogen receptor (ER). In the present study, 21 disinfection byproducts, selected for their predicted involvement in endocrine-related diseases and their structural diversity, were individually evaluated for their binding affinity to the human ER and in silico, and then a subset of these chemicals was studied in binary mixtures with the known weak estrogen, 4-n-nonylphenol. Individually, 9 of the 21 disinfection byproducts were able to weakly bind to the ER, with affinities ranging from log median inhibitory concentration values of -3.83 to -2.19 M. In binary mixtures, the chemicals followed concentration addition, with their weak binding affinities having little contribution to the overall mixture affinity. These results demonstrate the variety of small-molecule disinfection byproduct structures that are capable of binding to the ER, and that their weak binding can still be of importance when overall human exposure to mixtures of disinfection byproducts in disinfected drinking water is considered. Environ Toxicol Chem 2019;9999:1-9. © 2019 SETAC.

Long-Term Health Effects and Underlying Biological Mechanisms of Developmental Exposure to Arsenic.

PURPOSE OF REVIEW: Exposure to inorganic arsenic (iAs) via drinking water represents a significant global public health threat with chronic exposure associated with cancer, skin lesions, neurological impairment, and cardiovascular diseases. Particularly susceptible populations include the developing fetus and young children. This review summarizes some of the critical studies of the long-term health effects and underlying biological mechanisms related to developmental exposure to arsenic. It also highlights the complex factors, such as the sex of the exposed individual, that contribute to susceptibility to the later life health effects of iAs. RECENT FINDINGS: Studies in animal models, as well as human population-based studies, have established that prenatal and early life iAs exposures are associated with long-term effects, and many of these effects display sexually dimorphic responses. As an underlying molecular basis, recent epidemiologic and toxicologic studies have demonstrated that changes to the epigenome may play a key mechanistic role underlying many of the iAs-associated health outcomes. Developmental exposure to iAs results in early and later life health effects. Mechanisms underlying these outcomes are likely complex, and include disrupted key biological pathways with ties to the epigenome. This highlights the importance of continued research, particularly in animal models, to elucidate the important underpinnings (e.g., timing of exposure, metabolism, dose) of these complex health outcomes and to identify the biological mechanisms underlying sexual dimorphism in iAs-associated diseases. Future research should investigate preventative strategies for the protection from the detrimental health endpoints associated with early life exposure to iAs. Such strategies could include potential interventions focused on dietary supplementation for example the adoption of a folate-rich diet.

Epigenetic Regulation of the Nitric Oxide Pathway, 17-α Hydroxyprogesterone Caproate, and Recurrent Preterm Birth.

OBJECTIVE: We sought to evaluate nitric oxide pathway placental gene expression and the epigenome (CpG methylation) among women receiving 17-α hydroxyprogesterone caproate (17-OHPC) with and without recurrent preterm birth (PTB). STUDY DESIGN: This was a case-control study. We prospectively recruited women with ≥ 1 prior singleton spontaneous PTB <34 weeks receiving 17-OHPC. DNA and RNA were isolated from placentas. RNA abundance (gene expression) and the methylome were analyzed for 84 genes in nitric oxide pathways. Women with recurrent PTB <34 weeks (cases) were compared with those delivering at term (controls). Statistical analysis included multivariable models with Bonferroni's corrected p-values. RESULTS: In this study, 17 women met inclusion criteria; 7 preterm cases (delivered at 22.6 ± 2.9 weeks) and 10 term controls (delivered at 38.5 ± 0.8 weeks). Groups had similar PTB history, race/ethnicity, and socioeconomic risk factors for PTB. Twenty-seven nitric oxide genes displayed differential expression (p < 0.05 and q < 0.10) when comparing placentas from preterm cases and term controls; all were downregulated in preterm cases. Eight hundred sixty corresponding CpG sites were differentially methylated between the preterm cases and term controls (Bonferroni's p-value <0.05). CONCLUSION: CpG methylation and gene expression patterns in nitric oxide pathway genes differ among placentas from recurrent PTB compared with term birth following 17-OHPC exposure.

Identification of endocrine active disinfection by-products (DBPs) that bind to the androgen receptor.

The formation of disinfection by-products (DBPs) in drinking water occurs when chemical disinfectants such as chlorine and chloramine react with natural organic matter and anthropogenic pollutants. Some DBPs have been linked to bladder cancer and infertility; however, the underlying mechanism of action is unknown. One possibility is disruption of the endocrine system, with DBPs binding to the androgen receptor and subsequently altering gene expression. Using the androgen receptor-binding assay and in silico molecular docking, the binding affinity of 21 suspected and known DBPs were tested individually at concentrations over the range 0.1 nM-2 mM. 14 DBPs were found to bind at IC50 values ranging from 1.86 mM for 2,3-dichloropropionamide to 13.5 µM for 3,4,5,6-tetrachloro-benzoquinone as compared to the positive control, 4-n-nonylphenol which bound at 31.6 µM. Since DBPs are present in drinking waters as mixtures, the question of how IC50 values for individual DBPs might be affected by the presence of other chemicals is addressed. Seven of the chemicals with the strongest binding affinities and one chemical with no binding affinity were tested in binary mixtures with 4-n-nonylphenol, a known androgenic chemical found in some surface waters. In these binary mixtures, concentration additive binding was observed. While typical levels of individual androgenic DBPs in drinking water are below their measured IC50 values, their combined binding abilities in mixtures could be a source of androgen disruption.

Chronic early childhood exposure to arsenic is associated with a TNF-mediated proteomic signaling response.

Exposure to inorganic arsenic (iAs) in drinking water is a global public health concern and is associated with a range of health outcomes, including immune dysfunction. Children are a particularly sensitive population to the effects of inorganic arsenic, yet the biological mechanisms underlying adverse health outcomes are understudied. Here we used a proteomic approach to examine the effects of iAs exposure on circulating serum protein levels in a cross-sectional children's cohort in Mexico. To identify iAs-associated proteins, levels of total urinary arsenic (U-tAs) and its metabolites were determined and serum proteins assessed for differences in expression. The results indicate an enrichment of Tumor Necrosis Factor-(TNF)-regulated immune and inflammatory response proteins that displayed decreased expression levels in relation to increasing U-tAs. Notably, when analyzed in the context of the proportions of urinary arsenic metabolites in children, the most robust response was observed in relation to the monomethylated arsenicals. This study is among the first serum proteomics assessment in children exposed to iAs.

miRNAs as common regulators of the transforming growth factor (TGF)-ß pathway in the preeclamptic placenta and cadmium-treated trophoblasts: Links between the environment, the epigenome and preeclampsia.

Preeclampsia (PE) is a pregnancy disorder characterized by high blood pressure and proteinuria that can cause adverse health effects in both mother and fetus. There is no current cure for PE other than delivery of the fetus/placenta. While the etiology is unknown, poor placentation due to aberrant signaling of growth and angiogenic factors has been postulated as a causal factor of PE. In addition, environmental contaminants, such as the metal cadmium (Cd), have been linked to placental toxicity and increased risk of developing PE. Here, we use a translational study design to investigate genomic and epigenomic alterations in both placentas and placental trophoblasts, focused on the angiogenesis-associated transforming growth factor-beta (TGF-ß) pathway. Genes within the TGF-ß pathway displayed increased expression in both the preeclamptic placenta and Cd-treated trophoblasts. In addition, miRNAs that target the TGF-ß pathway were also significantly altered within the preeclamptic placenta and Cd-treated trophoblasts. Integrative analysis resulted in the identification of a subset of Cd-responsive miRNAs, including miR-26a and miR-155, common to preeclamptic placentas and Cd-treated trophoblasts. These miRNAs have previously been linked to PE and are predicted to regulate members of the TGF-ß pathway. Results from this study provide future targets for PE treatment.

Epigenetics and Preeclampsia: Defining Functional Epimutations in the Preeclamptic Placenta Related to the TGF-ß Pathway.

Preeclampsia is a potentially fatal pregnancy disorder affecting millions of women around the globe. Dysregulation in gene and protein expression within key biological pathways controlling angiogenesis has been implicated in the development of preeclampsia. Altered CpG methylation, a type of epimutation, may underlie this pathway dysregulation. In the present study, placental tissue from preeclamptic cases and normotensive controls was analyzed for genome-wide differential CpG methylation and concomitant changes in gene expression. A set of 123 genes, representing 19.9% of all genes with altered CpG methylation, was associated with functional changes in transcript levels. Underscoring the complex relationships between CpG methylation and gene expression, here hypermethylation was never associated with gene silencing, nor was hypomethylation always associated with gene activation. Moreover, the genomic region of the CpG mark was important in predicting the relationship between CpG methylation and gene expression. The 123 genes were enriched for their involvement in the transforming growth factor beta (TGF-ß) signaling pathway, a known regulator of placental trophoblast invasion and migration. This is the first study to identify CpG hypomethylation as an activator of TGF-ß-associated gene expression in the preeclamptic placenta. The results suggest functional epimutations are associated with preeclampsia disease status and the identified genes may represent novel biomarkers of disease.

Identification of novel gene targets and putative regulators of arsenic-associated DNA methylation in human urothelial cells and bladder cancer.

There is strong epidemiologic evidence linking chronic exposure to inorganic arsenic (iAs) to myriad adverse health effects, including cancer of the bladder. We set out to identify DNA methylation patterns associated with arsenic and its metabolites in exfoliated urothelial cells (EUCs) that originate primarily from the urinary bladder, one of the targets of arsenic-induced carcinogenesis. Genome-wide, gene-specific promoter DNA methylation levels were assessed in EUCs from 46 residents of Chihuahua, Mexico, and the relationship was examined between promoter methylation profiles and the intracellular concentrations of total arsenic and arsenic species. A set of 49 differentially methylated genes was identified with increased promoter methylation associated with EUC tAs, iAs, and/or monomethylated As (MMAs) enriched for their roles in metabolic disease and cancer. Notably, no genes had differential methylation associated with EUC dimethylated As (DMAs), suggesting that DMAs may influence DNA methylation-mediated urothelial cell responses to a lesser extent than iAs or MMAs. Further analysis showed that 22 of the 49 arsenic-associated genes (45%) are also differentially methylated in bladder cancer tissue identified using The Cancer Genome Atlas repository. Both the arsenic- and cancer-associated genes are enriched for the binding sites of common transcription factors known to play roles in carcinogenesis, demonstrating a novel potential mechanistic link between iAs exposure and bladder cancer.

DNA methylation modifies urine biomarker levels in 1,6-hexamethylene diisocyanate exposed workers: a pilot study.

DNA methylation may mediate inter-individual responses to chemical exposure and, thus, modify biomarker levels of exposure and effects. We analyzed inter-individual differences in inhalation and skin exposure to 1,6-hexamethylene diisocyanate (HDI) and urine biomarker 1,6-hexamethylene diamine (HDA) levels in 20 automotive spray-painters. Genome-wide 5-methyl cytosine (CpG) DNA methylation was assessed in each individual's peripheral blood mononuclear cells (PBMC) DNA using the Illumina 450K CpG array. Mediation analysis using linear regression models adjusted for age, ethnicity, and smoking was conducted to identify and assess the association between HDI exposure, CpG methylation, and urine HDA biomarker levels. We did not identify any CpGs common to HDI exposure and biomarker level suggesting that CpG methylation is a mediator that only partially explains the phenotype. Functional significance of genic- and intergenic-CpG methylation status was tested using protein-protein or protein-DNA interactions and gene-ontology enrichment to infer networks. Combined, the results suggest that methylation has the potential to affect HDI mass transport, permeation, and HDI metabolism. We demonstrate the potential use of PBMC methylation along with quantitative exposure and biomarker data to guide further investigation into the mediators of occupational exposure and biomarkers and its role in risk assessment.

Imprinted genes and the environment: links to the toxic metals arsenic, cadmium, lead and mercury.

Imprinted genes defy rules of Mendelian genetics with their expression tied to the parent from whom each allele was inherited. They are known to play a role in various diseases/disorders including fetal growth disruption, lower birth weight, obesity, and cancer. There is increasing interest in understanding their influence on environmentally-induced disease. The environment can be thought of broadly as including chemicals present in air, water and soil, as well as food. According to the Agency for Toxic Substances and Disease Registry (ATSDR), some of the highest ranking environmental chemicals of concern include metals/metalloids such as arsenic, cadmium, lead and mercury. The complex relationships between toxic metal exposure, imprinted gene regulation/expression and health outcomes are understudied. Herein we examine trends in imprinted gene biology, including an assessment of the imprinted genes and their known functional roles in the cell, particularly as they relate to toxic metals exposure and disease. The data highlight that many of the imprinted genes have known associations to developmental diseases and are enriched for their role in the TP53 and AhR pathways. Assessment of the promoter regions of the imprinted genes resulted in the identification of an enrichment of binding sites for two transcription factor families, namely the zinc finger family II and PLAG transcription factors. Taken together these data contribute insight into the complex relationships between toxic metals in the environment and imprinted gene biology.

Prenatal arsenic exposure and shifts in the newborn proteome: interindividual differences in tumor necrosis factor (TNF)-responsive signaling.

Exposure to inorganic arsenic (iAs) early in life is associated with adverse health effects in infants, children, and adults, and yet the biological mechanisms that underlie these effects are understudied. The objective of this research was to examine the proteomic shifts associated with prenatal iAs exposure using cord blood samples isolated from 50 newborns from Gómez Palacio, Mexico. Levels of iAs in maternal drinking water (DW-iAs) and the sum of iAs and iAs metabolites in maternal urine (U-tAs) were determined. Cord blood samples representing varying iAs exposure levels during the prenatal period (DW-iAs ranging from <1 to 236 µg As/l) were analyzed for altered expression of proteins associated with U-tAs using a high throughput, antibody-based method. A total of 111 proteins were identified that had a significant association between protein level in newborn cord blood and maternal U-tAs. Many of these proteins are regulated by tumor necrosis factor and are enriched in functionality related to immune/inflammatory response and cellular development/proliferation. Interindividual differences in proteomic response were observed in which 30 newborns were "activators," displaying a positive relationship between protein expression and maternal U-tAs. For 20 "repressor" newborns, a negative relationship between protein expression level and maternal U-tAs was observed. The activator/repressor status was significantly associated with maternal U-tAs and head circumference in newborn males. These results may provide a critical groundwork for understanding the diverse health effects associated with prenatal arsenic exposure and highlight interindividual responses to arsenic that likely influence differential susceptibility to adverse health outcomes.

Cadmium exposure and the epigenome: Exposure-associated patterns of DNA methylation in leukocytes from mother-baby pairs.

Cadmium (Cd) is prevalent in the environment yet understudied as a developmental toxicant. Cd partially crosses the placental barrier from mother to fetus and is linked to detrimental effects in newborns. Here we examine the relationship between levels of Cd during pregnancy and 5-methylcytosine (5mC) levels in leukocyte DNA collected from 17 mother-newborn pairs. The methylation of cytosines is an epigenetic mechanism known to impact transcriptional signaling and influence health endpoints. A methylated cytosine-guanine (CpG) island recovery assay was used to assess over 4.6 million sites spanning 16,421 CpG islands. Exposure to Cd was classified for each mother-newborn pair according to maternal blood levels and compared with levels of cotinine. Subsets of genes were identified that showed altered DNA methylation levels in their promoter regions in fetal DNA associated with levels of Cd (n = 61), cotinine (n = 366), or both (n = 30). Likewise, in maternal DNA, differentially methylated genes were identified that were associated with Cd (n = 92) or cotinine (n = 134) levels. While the gene sets were largely distinct between maternal and fetal DNA, functional similarities at the biological pathway level were identified including an enrichment of genes that encode for proteins that control transcriptional regulation and apoptosis. Furthermore, conserved DNA motifs with sequence similarity to specific transcription factor binding sites were identified within the CpG islands of the gene sets. This study provides evidence for distinct patterns of DNA methylation or "footprints" in fetal and maternal DNA associated with exposure to Cd.

Prenatal arsenic exposure and the epigenome: altered microRNAs associated with innate and adaptive immune signaling in newborn cord blood.

The Biomarkers of Exposure to ARsenic (BEAR) pregnancy cohort in Gómez Palacio, Mexico was recently established to better understand the impacts of prenatal exposure to inorganic arsenic (iAs). In this study, we examined a subset (n = 40) of newborn cord blood samples for microRNA (miRNA) expression changes associated with in utero arsenic exposure. Levels of iAs in maternal drinking water (DW-iAs) and maternal urine were assessed. Levels of DW-iAs ranged from below detectable values to 236 µg/L (mean = 51.7 µg/L). Total arsenic in maternal urine (U-tAs) was defined as the sum of iAs and its monomethylated and dimethylated metabolites (MMAs and DMAs, respectively) and ranged from 6.2 to 319.7 µg/L (mean = 64.5 µg/L). Genome-wide miRNA expression analysis of cord blood revealed 12 miRNAs with increasing expression associated with U-tAs. Transcriptional targets of the miRNAs were computationally predicted and subsequently assessed using transcriptional profiling. Pathway analysis demonstrated that the U-tAs-associated miRNAs are involved in signaling pathways related to known health outcomes of iAs exposure including cancer and diabetes mellitus. Immune response-related mRNAs were also identified with decreased expression levels associated with U-tAs, and predicted to be mediated in part by the arsenic-responsive miRNAs. Results of this study highlight miRNAs as novel responders to prenatal arsenic exposure that may contribute to associated immune response perturbations.

DNA methylation in nasal epithelial cells from smokers: identification of ULBP3-related effects.

We previously demonstrated that, in nasal epithelial cells (NECs) from smokers, methylation of an antiviral gene was associated with impaired antiviral defense responses. To expand these findings and better understand biological mechanisms underlying cigarette smoke (CS)-induced modifications of host defense responses, we aimed to compare DNA methylation of genes that may play a role in antiviral response. We used a two-tiered analytical approach, where we first implemented a genome-wide strategy. NECs from smokers differed in the methylation levels of 390 genes, the majority (84%) of which showed decreased methylation in smokers. Secondly, we generated an a priori set of 161 antiviral response-related genes, of which five were differentially methylated in NEC from smokers (CCL2, FDPS, GSK3B, SOCS3, and ULBP3). Assessing these genes at the systems biology level revealed a protein interaction network associated with CS-induced epigenetic modifications involving SOCS3 and ULBP3 signaling, among others. Subsequent confirmation studies focused on SOCS3 and ULBP3, which were hypomethylated and hypermethylated, respectively. Expression of SOCS3 was increased, whereas ULBP3 expression was decreased in NECs from smokers. Addition of the demethylating agent 5-Aza-2-deoxycytidine enhanced ULBP3 expression in NECs from smokers. Furthermore, infection of differentiated NECs with influenza virus resulted in significantly lower levels of ULBP3 in cells from smokers. Taken together, our findings show that genomic DNA methylation profiles are altered in NECs from smokers and that these changes are associated with decreased antiviral host defense responses, indicating that epigenenic dysregulation of genes such as SOCS3 and ULBP3 likely impacts immune responses in the epithelium.