Biomarkers of exposure to tobacco smoke and environmental pollutants in mothers and their transplacental transfer to the foetus. Part I: bulky DNA adducts

Effects of polycyclic aromatic hydrocarbons (PAHs) on pregnancy, placenta, and placental trophoblasts

Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent organic pollutants that are carcinogenic, mutagenic, endocrine-toxic, and immunotoxic. PAHs can be found in maternal and fetal blood and in the placenta during pregnancy. They may thus affect placental and fetal development. Therefore, the exposure levels and toxic effects of PAHs in the placenta deserve further study and discussion. This review aims to summarize current knowledge on the effects of PAHs and their metabolites on pregnancy and birth outcomes and on placental trophoblast cells. A growing number of epidemiological studies detected PAH-DNA adducts as well as the 16 high-priority PAHs in the human placenta and showed that placental PAH exposure is associated with adverse fetal outcomes. Trophoblasts are important cells in the placenta and are involved in placental development and function. In vitro studies have shown that exposure to either PAH mixtures, benzo(a)pyrene (BaP) or BaP metabolite benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) affected trophoblast cell viability, differentiation, migration, and invasion through various signaling pathways. Furthermore, similar effects of BPDE on trophoblast cells could also be observed in BaP-treated mouse models and were related to miscarriage. Although the current data show that PAHs may affect placental trophoblast cells and pregnancy outcomes, further studies (population studies, in vitro studies, and animal studies) are necessary to show the specific effects of different PAHs on placental trophoblasts and pregnancy outcomes.

Benzo(a)pyrene and Cerium Dioxide Nanoparticles in Co-Exposure Impair Human Trophoblast Cell Stress Signaling

Human placenta is a multifunctional interface between maternal and fetal blood. Studying the impact of pollutants on this organ is crucial because many xenobiotics in maternal blood can accumulate in placental cells or pass into the fetal circulation. Benzo(a)pyrene (BaP) and cerium dioxide nanoparticles (CeO2 NP), which share the same emission sources, are found in ambient air pollution and also in maternal blood. The aim of the study was to depict the main signaling pathways modulated after exposure to BaP or CeO2 NP vs. co-exposure on both chorionic villi explants and villous cytotrophoblasts isolated from human term placenta. At nontoxic doses of pollutants, BaP is bioactivated by AhR xenobiotic metabolizing enzymes, leading to DNA damage with an increase in γ-H2AX, the stabilization of stress transcription factor p53, and the induction of its target p21. These effects are reproduced in co-exposure with CeO2 NP, except for the increase in γ-H2AX, which suggests a modulation of the genotoxic effect of BaP by CeO2 NP. Moreover, CeO2 NP in individual and co-exposure lead to a decrease in Prx-SO3, suggesting an antioxidant effect. This study is the first to identify the signaling pathways modulated after co-exposure to these two pollutants, which are common in the environment.

Maternal exposure to cooking oil fumes during pregnancy and autistic-like behaviors in Chinese preschoolers

There is growing evidence that cooking oil fumes (COFs) are harmful indoor air pollutants. However, there is a dearth of research investigating whether maternal COFs exposure during pregnancy may affect children's autistic-like behaviors in China. This study aimed to explore this association, and examine the effects of different cooking fuels and ventilation methods used by mothers on the presence of autistic-like behaviors. This study analyzed the survey data of the Longhua Child Cohort Study in 2017 with a total of 62,372 mothers enrolled in this study. A self-administrative questionnaire was used to collect information on socio-demographic characteristics, cooking habits during pregnancy, and autistic-like behaviors (measured using the Autism Behavior Checklist). After adjusting for potential confounders, the results showed that compared with children whose mothers never cooked during pregnancy, children whose mothers cooked sometimes, often, always during pregnancy had the higher risk of autistic-like behaviors. As the amounts of COFs exposed to and the frequency of cooking during pregnancy increased, the risk of a child's autistic-like behaviors also increased. Mothers using natural gas as cooking fuels had a lower risk of their child having autistic-like behaviors, compared with mothers using coal or other cooking fuels. Furthermore, pregnant women using ventilation measures during cooking significantly decreased likelihood of the presence of autistic-like behaviors in their children. These results suggest that maternal exposure to COFs during pregnancy may increase the likelihood of the presence of autistic-like behaviors in offspring. These findings support a recommendation that pregnant women should avoid exposure to COFs and use clean fuels and ventilation equipment in kitchens to reduce the risk of autistic-like behaviors in children.

Polycyclic aromatic hydrocarbons (PAHs) may explain the paradoxical effects of cigarette use on preeclampsia (PE)

Tobacco smoking and use of snus (smokeless tobacco) are associated with adverse effects on pregnancy and neonatal outcomes. Nicotine is considered a key toxicant involved in effects caused by both smoking and snus, while pyrolysis products including polycyclic aromatic hydrocarbons (PAHs) in cigarette smoke represents the constituents most unequally divided between these two groups of tobacco products. The aim of this review was: i) to compare the impact, in terms of relative effect estimates, of cigarette smoking and use of Swedish snus on pregnancy outcomes using similar non-tobacco user controls, and ii) to examine whether exposure to PAHs from smoking could explain possible differences in impact on pregnancy outcomes. We systematically searched MEDLINE, Embase, PsycInfo, Web of Science and the Cochrane Database of Systematic Reviews up to October 2021 and identified studies reporting risks for adverse pregnancy and neonatal outcomes associated with snus use and with smoking relative to pregnant women with no use of tobacco. Both snus use and smoking were associated with increased risk of stillbirth, preterm birth, and oral cleft malformation, with comparable point estimates. These effects were likely due to comparable nicotine exposure. We also found striking differences. While both smoking and snus increased the risk of having small for gestational age (SGA) infants, risk from maternal smoking was markedly higher as was the reduction in birthweight. In contrast, the risk of preeclampsia (PE) was markedly lower in smokers than in controls, while snus use was associated with a slightly increased risk. We suggest that PAHs acting via AhR may explain the stronger effects of tobacco smoking on SGA and also to the apparent protective effect of cigarette smoking on PE. Possible mechanisms involved include: i) disrupted endocrine control of fetal development as well as placental development and function, and ii) stress adaption and immune suppression in placenta and mother.

Smoking for two- effects of tobacco consumption on placenta

Tobacco smoking is an important public health issue recognized by the world health organization as one of the most serious, preventable risk factors for developing a series of pregnancy pathologies. Maternal smoking is positively associated with intrauterine growth restriction (IUGR) and gestational diabetes (GDM), but negatively associated with preeclampsia (PE). In this review, we examine epidemiological, clinical and laboratory studies of smoking effects on immunoregulation during pregnancy, trophoblast function, and placental vasculature development and metabolism. We aim to identify effects of tobacco smoke components on specific placental compartments or cells, which may contribute to the understanding of the influences of maternal smoking on placenta function in normal and pathological pregnancies. Data corroborates that in any trimester, smoking is unsafe for pregnancy and that its detrimental effects outweigh questionable benefits. The effects of maternal smoking on the maternal immune regulation throughout pregnancy and the impact of different tobacco products on fetal growth have not yet been fully understood. Smoking cessation rather than treatment with replacement therapies is recommended for future mothers because also single components of tobacco and its smoke may have detrimental effects on placental function.

Environmental Pollutant Benzo[a]pyrene Upregulated Long Non-coding RNA HZ07 Inhibits Trophoblast Cell Migration by Inactivating PI3K/AKT/MMP2 Signaling Pathway in Recurrent Pregnancy Loss

Benzo(a)pyrene (BaP) is a ubiquitous environmental endocrine-disrupting chemical that is known to have toxic effects on reproduction. However, the underlying mechanisms describing how BaP and its metabolite benzo[a]pyrene-7, 8-diol-9, 10-epoxide (BPDE) induce recurrent pregnancy loss (RPL) are still largely unclear. In this study, we identified a novel long non-coding RNA (lnc-HZ07, NCBI MT936329) that was upregulated in trophoblast cells after exposure to BPDE, and lnc-HZ07 expression was significantly higher in RPL villous tissues than that in control villous tissues. Knockdown of lnc-HZ07 promoted trophoblast cell migration, whereas overexpression of lnc-HZ07 inhibited trophoblast cell migration. Further study showed that lnc-HZ07 inhibited trophoblast migration by downregulating matrix metalloproteinase 2 (MMP2) expression via dephosphorylation of AKT. These results demonstrated a novel regulatory pathway in which BaP downregulated AKT phosphorylation and inhibited MMP2 expression by upregulating lnc-HZ07, suggesting that lnc-HZ07 could be considered as a potential pathological marker of BaP-induced RPL and therapeutic target for this disease.

The role of xenobiotic-metabolizing enzymes in the placenta: a growing research field

Introduction: The placenta is a temporary and unique organ that allows for the physical connection between a mother and fetus; this organ regulates the transport of gases and nutrients mediating the elimination of waste products contained in the fetal circulation. The placenta performs metabolic and excretion functions, on the basis of multiple enzymatic systems responsible for the oxidation, reduction, hydrolysis, and conjugation of xenobiotics. These mechanisms give the placenta a protective role that limits the fetal exposure to harmful compounds. During pregnancy, some diseases require uninterrupted treatment even if it is detrimental to the fetus. Drugs and other xenobiotics alter gene expression in the placenta with repercussions for the fetus and mother's well-being.Areas covered: This review provides a brief description of the human placental structure and function, the main drug and xenobiotic transporters and metabolizing enzymes, placenta-metabolized substrates, and alterations in gene expression that the exposure to xenobiotics may cause.Expert opinion: Research should be focused on the identification and validation of biological markers for the assessment of the harmful effects of some drugs in pregnancy, including the evaluation of polymorphisms and methylation patterns in chorionic villous samples and/or amniotic fluid.

Prenatal exposure to particulate matter and ozone: Bulky DNA adducts, plasma isoprostanes, allele risk variants, and neonate susceptibility in the Mexico City Metropolitan Area

Mexico City's Metropolitan Area (MCMA) includes Mexico City and 60 municipalities of the neighbor states. Inhabitants are exposed to emissions from over five million vehicles and stationary sources of air pollutants such as particulate matter (PM) and ozone. MCMA PM contains elemental carbon and organic carbon (OC). OCs include polycyclic aromatic hydrocarbons (PAHs), many of which induce mutagenic and carcinogenic DNA adducts. Gestational exposure to air pollution has been associated with increased risk of intrauterine growth restriction, preterm birth or low birth weight risk, and PAH-DNA adducts. These effects also depend on the presence of risk alleles. We investigated the presence of bulky PAH-DNA adducts, plasma 8-iso-PGF_2α (8-iso-prostaglandin F_2α ) and risk allele variants in neonates cord blood and their non-smoking mothers' leucocytes from families that were living in a highly polluted area during 2014-2015. The presence of adducts was significantly associated with both PM_2.5 and PM₁₀ levels, mainly during the last trimester of gestation in both neonates and mothers, while the last month of pregnancy was significant for the association between ozone levels and maternal plasma 8-iso-PGF_2α . Fetal CYP1B1*3 risk allele was associated with increased adduct levels in neonates while the presence of the maternal allele significantly reduced the levels of fetal adducts. Maternal NQO1*2 was associated with lower maternal levels of adducts. Our findings suggest the need to reduce actual PM limits in MCMA. We did not observe a clear association between PM and/or adduct levels and neonate weight, length, body mass index, Apgar or Capurro score. Environ. Mol. Mutagen. 60:428-442, 2019. © 2019 Wiley Periodicals, Inc.

Transplacental exposure to carcinogens and risks to children: evidence from biomarker studies and the utility of omic profiling

The factors underlying the increasing rates and the geographic variation of childhood cancers are largely unknown. Epidemiological studies provide limited evidence for a possible role in the etiology of certain types of childhood cancer of the exposure of pregnant women to environmental carcinogens (e.g., tobacco smoke and pesticides); however, such evidence is inadequate to allow definitive conclusions. Complementary evidence can be obtained from biomarker-based population studies. Such studies have demonstrated that, following exposure of pregnant mothers, most environmental carcinogens reach the fetus and, in many cases, induce therein genotoxic damage which in adults is known to be associated with increased cancer risk, implying that environmental carcinogens may contribute to the etiology of childhood cancer. During recent years, intermediate disease biomarkers, obtained via omic profiling, have provided additional insights into the impact of transplacental exposures on fetal tissues which, in some cases, are also compatible with a precarcinogenic role of certain in utero exposures. Here we review the epidemiological and biomarker evidence and discuss how further research, especially utilizing high-density profiling, may allow a better evaluation of the links between in utero environmental exposures and cancer in children.

Expression, Localization, and Activity of the Aryl Hydrocarbon Receptor in the Human Placenta

The human placenta is an organ between the blood of the mother and the fetus, which is essential for fetal development. It also plays a role as a selective barrier against environmental pollutants that may bypass epithelial barriers and reach the placenta, with implications for the outcome of pregnancy. The aryl hydrocarbon receptor (AhR) is one of the most important environmental-sensor transcription factors and mediates the metabolism of a wide variety of xenobiotics. Nevertheless, the identification of dietary and endogenous ligands of AhR suggest that it may also fulfil physiological functions with which pollutants may interfere. Placental AhR expression and activity is largely unknown. We established the cartography of AhR expression at transcript and protein levels, its cellular distribution, and its transcriptional activity toward the expression of its main target genes. We studied the profile of AhR expression and activity during different pregnancy periods, during trophoblasts differentiation in vitro, and in a trophoblast cell line. Using diverse methods, such as cell fractionation and immunofluorescence microscopy, we found a constitutive nuclear localization of AhR in every placental model, in the absence of any voluntarily-added exogenous activator. Our data suggest an intrinsic activation of AhR due to the presence of endogenous placental ligands.

Air pollution and the fetal origin of disease: A systematic review of the molecular signatures of air pollution exposure in human placenta

BACKGROUND

Fetal development is a crucial window of susceptibility in which exposure-related alterations can be induced on the molecular level, leading to potential changes in metabolism and development. The placenta serves as a gatekeeper between mother and fetus, and is in contact with environmental stressors throughout pregnancy. This makes the placenta as a temporary organ an informative non-invasive matrix suitable to investigate omics-related aberrations in association with in utero exposures such as ambient air pollution.

OBJECTIVES

To summarize and discuss the current evidence and define the gaps of knowledge concerning human placental -omics markers in association with prenatal exposure to ambient air pollution.

METHODS

Two investigators independently searched the PubMed, ScienceDirect, and Scopus databases to identify all studies published until January 2017 with an emphasis on epidemiological research on prenatal exposure to ambient air pollution and the effect on placental -omics signatures.

RESULTS

From the initial 386 articles, 25 were retained following an a priori set inclusion and exclusion criteria. We identified eleven studies on the genome, two on the transcriptome, five on the epigenome, five on the proteome category, one study with both genomic and proteomic topics, and one study with both genomic and transcriptomic topics. Six studies discussed the triple relationship between exposure to air pollution during pregnancy, the associated placental -omics marker(s), and the potential effect on disease development later in life. So far, no metabolomic or exposomic data discussing associations between the placenta and prenatal exposure to air pollution have been published.

CONCLUSIONS

Integration of placental biomarkers in an environmental epidemiological context enables researchers to address fundamental questions essential in unraveling the fetal origin of disease and helps to better define the pregnancy exposome of air pollution.

Gene expression profiling in healthy newborns from diverse localities of the Czech Republic

Prenatal exposure to air pollution is associated with intrauterine growth restriction and low birth weight. Gene expression changes in newborns in relation to air pollution have not been sufficiently studied. We analyzed whole genome expression in cord blood leukocytes of 202 newborns from diverse localities of the Czech Republic, differing among other factors in levels of air pollution: the district of Karvina (characterized by higher concentration of air pollutants) and Ceske Budejovice (lower air pollution levels). We aimed to identify differentially expressed genes (DEGs) and pathways in relation to locality and concentration of air pollutants. We applied the linear model to identify the specific DEGs and the correlation analysis, to investigate the relationship between the concentrations of air pollutants and gene expression data. An analysis of biochemical pathways and gene set enrichment was also performed. In general, we observed modest changes of gene expression, mostly attributed to the effect of the locality. The highest number of DEGs was found in samples from the district of Karvina. A pathway analysis revealed a deregulation of processes associated with cell growth, apoptosis or cellular homeostasis, immune response-related processes or oxidative stress response. The association between concentrations of air pollutants and gene expression changes was weak, particularly for samples collected in Karvina. In summary, as we did not find a direct effect of exposure to air pollutants, we assume that the general differences in the environment, rather than actual concentrations of individual pollutants, represent a key factor affecting gene expression changes at delivery. Environ. Mol. Mutagen. 59:401-415, 2018. © 2018 Wiley Periodicals, Inc.

Endocrine Disruptors and Developmental Origins of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a growing epidemic worldwide, particularly in countries that consume a Western diet, and can lead to life-threatening conditions such as cirrhosis and hepatocellular carcinoma. With increasing prevalence of NAFLD in both children and adults, an understanding of the factors that promote NAFLD development and progression is crucial. Environmental agents, including endocrine-disrupting chemicals (EDCs), which have been linked to other diseases, may play a role in NAFLD development. Increasing evidence supports a developmental origin of liver disease, and early-life exposure to EDCs could represent one risk factor for the development of NAFLD later in life. Rodent studies provide the strongest evidence for this link, but further studies are needed to define whether there is a causal link between early-life EDC exposure and NAFLD development in humans. Elucidating the molecular mechanisms underlying development of NAFLD in the context of developmental EDC exposures may identify biomarkers for people at risk, as well as potential intervention and/or therapeutic opportunities for the disease.

Modification of adverse health effects of maternal active and passive smoking by genetic susceptibility: Dose-dependent association of plasma cotinine with infant birth size among Japanese women-The Hokkaido Study

OBJECTIVES

We aimed to assess the individual dose-response effects of eight maternal polymorphisms encoding polycyclic aromatic hydrocarbon-metabolizing and DNA-repair genes on prenatal cotinine levels according to infant birth size.

METHODS

In total, 3263 Japanese pregnant women were assigned to five groups based on plasma cotinine levels during the 8th month of pregnancy, as measured using ELISA (cut-offs: 0.21, 0.55, 11.48, and 101.67ng/mL). Analyses were performed using multiple linear regression.

RESULTS

Birth weight reduction showed a dose-dependent relationship with prenatal cotinine levels (P for trend<0.001). When considering the specific aromatic hydrocarbon receptor (AHR) (G>A, Arg554Lys; db SNP ID: rs2066853) and X-ray cross-complementing gene 1 (XRCC1) (C>T, Arg194Trp, rs1799782) genotypes, a larger birth weight reduction was noted among infants born to mothers with the highest cotinine level.

CONCLUSION

Infants born to women with specific AHR and XRCC1 genotypes may have higher genetic risks for birth weight reduction.

Polycyclic aromatic hydrocarbons and PAH-related DNA adducts

Investigations on the impact of chemicals on the environment and human health have led to the development of an exposome concept. The exposome refers to the totality of exposures received by a person during life, including exposures to life-style factors, from the prenatal period to death. The exposure to genotoxic chemicals and their reactive metabolites can induce chemical modifications of DNA, such as, for example, DNA adducts, which have been extensively studied and which play a key role in chemically induced carcinogenesis. Development of different methods for the identification of DNA adducts has led to adopting DNA adductomic approaches. The ability to simultaneously detect multiple PAH-derived DNA adducts may allow for the improved assessment of exposure, and offer a mechanistic insight into the carcinogenic process following exposure to PAH mixtures. The major advantage of measuring chemical-specific DNA adducts is the assessment of a biologically effective dose. This review provides information about the occurrence of the polycyclic aromatic hydrocarbons (PAHs) and their influence on human exposure and biological effects, including PAH-derived DNA adduct formation and repair processes. Selected methods used for determination of DNA adducts have been presented.

Placental biomarkers of PAH exposure and glutathione-S-transferase biotransformation enzymes in an obstetric population from Tijuana, Baja California, Mexico

Environmental exposures along the US-Mexico border have the potential to adversely affect the maternal-fetal environment. The purpose of this study was to assess placental biomarkers of environmental exposures in an obstetric population at the California-Baja California border in relation to detoxifying enzymes in the placenta and nutritional status. This study was conducted on consenting, full-term, obstetric patients (n=54), delivering in a hospital in Tijuana, Baja California (BC), Mexico. Placental polyaromatic hydrocarbon (PAH)-DNA adducts were measured in addition to placental glutathione-S-transferase (GST) activity and genotype, maternal serum folate, and maternal and umbilical cord blood lead and cadmium levels. A questionnaire was administered to the mothers to determine maternal occupation in a maquiladora, other exposures, and obstetric indicators. In univariate analysis, maternal serum folate levels were inversely correlated with total PAH-DNA adducts (rho=-0.375, p=0.007); adduct #1 (rho=-0.388, p=0.005); and adduct #3 (rho =-0.430, p=0.002). Maternal lead levels were significantly positively correlated with cord blood lead levels (rho=0.512, p<0.001). Cadmium levels were generally very low but significantly higher in mothers exposed to environmental tobacco smoke (ETS) (either at work or at home, n=10). In multivariate analysis, only maternal serum folate levels remained as a significant negative predictor of total DNA-PAH adducts levels in placenta. These findings affirm that placental tissue is a valuable and readily available source of human tissue for biomonitoring; and indicate that further study of the role of nutrition in detoxification and mitigation of environmental exposures in pregnant women is warranted.

Parental Tobacco Smoking and Acute Myeloid Leukemia: The Childhood Leukemia International Consortium

The association between tobacco smoke and acute myeloid leukemia (AML) is well established in adults but not in children. Individual-level data on parental cigarette smoking were obtained from 12 case-control studies from the Childhood Leukemia International Consortium (CLIC, 1974-2012), including 1,330 AML cases diagnosed at age <15 years and 13,169 controls. We conducted pooled analyses of CLIC studies, as well as meta-analyses of CLIC and non-CLIC studies. Overall, maternal smoking before, during, or after pregnancy was not associated with childhood AML; there was a suggestion, however, that smoking during pregnancy was associated with an increased risk in Hispanics (odds ratio = 2.08, 95% confidence interval (CI): 1.20, 3.61) but not in other ethnic groups. By contrast, the odds ratios for paternal lifetime smoking were 1.34 (95% CI: 1.11, 1.62) and 1.18 (95% CI: 0.92, 1.51) in pooled and meta-analyses, respectively. Overall, increased risks from 1.2- to 1.3-fold were observed for pre- and postnatal smoking (P < 0.05), with higher risks reported for heavy smokers. Associations with paternal smoking varied by histological type. Our analyses suggest an association between paternal smoking and childhood AML. The association with maternal smoking appears limited to Hispanic children, raising questions about ethnic differences in tobacco-related exposures and biological mechanisms, as well as study-specific biases.

Impact of exposure to cooking fuels on stillbirths, perinatal, very early and late neonatal mortality - a multicenter prospective cohort study in rural communities in India, Pakistan, Kenya, Zambia and Guatemala

Background

Consequences of exposure to household air pollution (HAP) from biomass fuels used for cooking on neonatal deaths and stillbirths is poorly understood. In a large multi-country observational study, we examined whether exposure to HAP was associated with perinatal mortality (stillbirths from gestation week 20 and deaths through day 7 of life) as well as when the deaths occurred (macerated, non-macerated stillbirths, very early neonatal mortality (day 0–2) and later neonatal mortality (day 3–28).

Questions addressing household fuel use were asked at pregnancy, delivery, and neonatal follow-up visits in a prospective cohort study of pregnant women in rural communities in five low and lower middle income countries participating in the Global Network for Women and Children’s Health’s Maternal and Newborn Health Registry. The study was conducted between May 2011 and October 2012. Polluting fuels included kerosene, charcoal, coal, wood, straw, crop waste and dung. Clean fuels included electricity, liquefied petroleum gas (LPG), natural gas and biogas.

Results

We studied the outcomes of 65,912 singleton pregnancies, 18 % from households using clean fuels (59 % LPG) and 82 % from households using polluting fuels (86 % wood). Compared to households cooking with clean fuels, there was an increased risk of perinatal mortality among households using polluting fuels (adjusted relative risk (aRR) 1.44, 95 % confidence interval (CI) 1.30-1.61). Exposure to HAP increased the risk of having a macerated stillbirth (adjusted odds ratio (aOR) 1.66, 95%CI 1.23-2.25), non-macerated stillbirth (aOR 1.43, 95 % CI 1.15-1.85) and very early neonatal mortality (aOR 1.82, 95 % CI 1.47-2.22).

Conclusions

Perinatal mortality was associated with exposure to HAP from week 20 of pregnancy through at least day 2 of life. Since pregnancy losses before labor and delivery are difficult to track, the effect of exposure to polluting fuels on global perinatal mortality may have previously been underestimated.

Trial registration

ClinicalTrials.gov NCT01073475

Transplacental transfer of 2-naphthol in human placenta

Objective

To determine the transfer of 2-naphthol (2-NPH) in fullterm human placental tissues.

Methods

Six placentas were studied. The ex-vivo dual closed-loop human placental cotyledon perfusion model was used. 2-NPH was added to the perfusate in the maternal compartment. Samples were obtained from the maternal and fetal up to 360 min measuring.

Results

The mean fetal weight was 2880 ± 304.2 g. Mean perfused cotyledon weight was 26.3 (±5.5) g. All unperfused placental tissue samples contained NPH with a mean level of 7.98 (±1.73) μg\g compared to a mean of 15.58 (±4.53) μg\g after 360 min perfusion. A rapid drop in maternal 2-NPH concentration was observed; from 5.54 μg\g in the first 15 min and 13.8 μg\g in 360 min. The fetal side increased from 0.65 μg\g in the initial 15 min to 1.5 μg\g in 360 min. The transfer rate of NPH was much lower than that of antipyrine.

Conclusion

2-NPH has the ability to rapidly across the placenta from the maternal to the fetal compartment within 15 min. The placenta seems to play a role in limiting the passage of 2-NPH in the fetal compartment.

Environmental, dietary, maternal, and fetal predictors of bulky DNA adducts in cord blood: a European mother-child study (NewGeneris)

BACKGROUND

Bulky DNA adducts reflect genotoxic exposures, have been associated with lower birth weight, and may predict cancer risk.

OBJECTIVE

We selected factors known or hypothesized to affect in utero adduct formation and repair and examined their associations with adduct levels in neonates.

METHODS

Pregnant women from Greece, Spain, England, Denmark, and Norway were recruited in 2006-2010. Cord blood bulky DNA adduct levels were measured by the 32P-postlabeling technique (n = 511). Diet and maternal characteristics were assessed via questionnaires. Modeled exposures to air pollutants and drinking-water disinfection by-products, mainly trihalomethanes (THMs), were available for a large proportion of the study population.

RESULTS

Greek and Spanish neonates had higher adduct levels than the northern European neonates [median, 12.1 (n = 179) vs. 6.8 (n = 332) adducts per 108 nucleotides, p < 0.001]. Residence in southern European countries, higher maternal body mass index, delivery by cesarean section, male infant sex, low maternal intake of fruits rich in vitamin C, high intake of dairy products, and low adherence to healthy diet score were statistically significantly associated with higher adduct levels in adjusted models. Exposure to fine particulate matter and nitrogen dioxide was associated with significantly higher adducts in the Danish subsample only. Overall, the pooled results for THMs in water show no evidence of association with adduct levels; however, there are country-specific differences in results with a suggestion of an association in England.

CONCLUSION

These findings suggest that a combination of factors, including unknown country-specific factors, influence the bulky DNA adduct levels in neonates.

Exocyclic DNA adducts in sheep with skeletal fluorosis resident in the proximity of the Portoscuso-Portovesme industrial estate on Sardinia Island, Italy

The mechanisms by which fluoride produces its toxic effects are still not clear.

Genetic modification of the effect of maternal household air pollution exposure on birth weight in Guatemalan newborns

Low birth weight is associated with exposure to air pollution during pregnancy. The purpose of this study was to evaluate whether null polymorphisms of Glutathione S-transferases (GSTs), specifically GSTM1 and GSTT1 genes in infants or mothers, modify the association between high exposures to household air pollution (HAP) from cooking fires and birth weight. Pregnant women in rural Guatemala were randomized to receive a chimney stove or continue to use open fires for cooking. Newborns were measured within 48 h of birth. 132 mother-infant pairs provided infant genotypes (n=130) and/or maternal genotypes (n=116). Maternal null GSTM1 was associated with a 144 g (95% CI, -291, 1) and combined maternal/infant null GSTT1 was associated with a 155 g (95% CI, -303, -8) decrease in birth weight. Although there was a trend toward higher birth weights with increasing number of expressed GST genes, the effect modification by chimney stove use was not demonstrated.

Oxidative damage to nucleic acids and benzo(a)pyrene-7,8-diol-9,10-epoxide-DNA adducts and chromosomal aberration in children with psoriasis repeatedly exposed to crude coal tar ointment and UV radiation

The paper presents a prospective cohort study. Observed group was formed of children with plaque psoriasis (n=19) treated by Goeckerman therapy (GT). The study describes adverse (side) effects associated with application of GT (combined exposure of 3% crude coal tar ointment and UV radiation). After GT we found significantly increased markers of oxidative stress (8-hydroxy-2′-deoxyguanosine, 8-hydroxyguanosine, and 8-hydroxyguanine), significantly increased levels of benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE) DNA adducts (BPDE-DNA), and significantly increased levels of total number of chromosomal aberrations in peripheral lymphocytes. We found significant relationship between (1) time of UV exposure and total number of aberrated cells and (2) daily topical application of 3% crude coal tar ointment (% of body surface) and level of BPDE-DNA adducts. The findings indicated increased hazard of oxidative stress and genotoxic effects related to the treatment. However, it must be noted that the oxidized guanine species and BPDE-DNA adducts also reflect individual variations in metabolic enzyme activity (different extent of bioactivation of benzo[a]pyrene to BPDE) and overall efficiency of DNA/RNA repair system. The study confirmed good effectiveness of the GT (significantly decreased PASI score).

Maternal occupational exposure to polycyclic aromatic hydrocarbons and small for gestational age offspring

OBJECTIVES

While some of the highest maternal exposures to polycyclic aromatic hydrocarbons (PAHs) occur in the workplace, there is only one previous study of occupational PAH exposure and adverse pregnancy outcomes. We sought to extend this literature using interview data combined with detailed exposure assessment.

METHODS

Data for 1997-2002 were analysed from mothers of infants without major birth defects in the National Birth Defects Prevention Study, a large population-based case-control study in the USA. Maternal telephone interviews yielded information on jobs held in the month before conception through delivery. From 6252 eligible control mothers, 2803 completed the interview, had a job, met other selection criteria, and were included in the analysis. Two industrial hygienists independently assessed occupational exposure to PAHs from the interview and reviewed results with a third to reach consensus. Small for gestational age (SGA) was the only adverse pregnancy outcome with enough exposed cases to yield meaningful results. Logistic regression estimated crude and adjusted ORs.

RESULTS

Of the 2803 mothers, 221 (7.9%) had infants who were SGA. Occupational PAH exposure was found for 17 (7.7%) of the mothers with SGA offspring and 102 (4.0%) of the remaining mothers. Almost half the jobs with exposure were related to food preparation and serving. After adjustment for maternal age, there was a significant association of occupational exposure with SGA (OR=2.2, 95% CI 1.3 to 3.8).

CONCLUSIONS

Maternal occupational exposure to PAHs was found to be associated with increased risk of SGA offspring.

Serum level of antibody against benzo[a]pyrene-7,8-diol-9,10-epoxide-DNA adducts in people dermally exposed to PAHs

Some specific antibodies indicate the presence of antigenic structures on DNA (DNA adducts) that can play an important role in the process of mutagenesis and/or carcinogenesis. They indicate the presence of increased genotoxic potential (hazard) prior to the formation of disease (primary prevention). The present study was focused on the serum level of benzo[a]pyrene 7,8-diol-9,10-epoxide-DNA adducts antibodies (anti-BPDE-DNA) in psoriatic patients (n = 55) dermally exposed to different levels of polycyclic aromatic hydrocarbons (PAHs). The general goal of the study was to contribute to better understanding of the value of the assumed biomarker (anti-BPDE-DNA) for evaluation of the organism's answer to genotoxic exposure to PAHs. Elevated level of exposure to PAHs resulted in the increased level of anti-BPDE-DNA. However, almost all levels of anti-BPDE-DNA ranged within the field of low values. Both variants of GT (CCT-3% and CCT-5%) induced higher expression of anti-BPDE-DNA in the group of nonsmokers. Significant relations between the level of anti-BPDE-DNA and PASI score, total duration of the therapy, or time of UVR exposure were not found. Further studies are needed to reduce interpretation uncertainty of this promising bioindicator.

Relationships of chemical concentrations in maternal and cord blood: a review of available data

The developing fetus is likely to be exposed to the same environmental chemicals as the mother during critical periods of growth and development. The degree of maternal-fetal transfer of chemical compounds will be affected by chemical and physical properties such as lipophilicity, protein binding, and active transport mechanisms that influence absorption and distribution in maternal tissues. However, these transfer processes are not fully understood for most environmental chemicals. This review summarizes reported data from more than 100 studies on the ratios of cord:maternal blood concentrations for a range of chemicals including brominated flame-retardant compounds, polychlorinated biphenyls (PCB), polychlorinated dibenzodioxins and dibenzofurans, organochlorine pesticides, perfluorinated compounds, polyaromatic hydrocarbons, metals, and tobacco smoke components. The studies for the chemical classes represented suggest that chemicals frequently detected in maternal blood will also be detectable in cord blood. For most chemical classes, cord blood concentrations were found to be similar to or lower than those in maternal blood, with reported cord:maternal ratios generally between 0.1 and 1. Exceptions were observed for selected brominated flame-retardant compounds, polyaromatic hydrocarbons, and some metals, for which reported ratios were consistently greater than 1. Careful interpretation of the data in a risk assessment context is required because measured concentrations of environmental chemicals in cord blood (and thus the fetus) do not necessarily imply adverse effects or risk. Guidelines and recommendations for future cord:maternal blood biomonitoring studies are discussed.

Lower nucleotide excision repair capacity in newborns compared to their mothers: a pilot study

Recognition of the potential vulnerability of children and newborns and protection of their health is essential, especially regarding to genotoxic compounds. Benzo(a)pyrene B(a)P a commonly found carcinogen, and its metabolite BPDE, are known to cross the placenta. To investigate how well newborns are able to cope with BPDE-induced DNA damage, a recent developed nucleotide excision repair cell phenotype assay was applied in a pilot study of 25 newborn daughters and their mothers, using the Alkaline Comet Assay and taking demographic data into account. Newborns seemed to be less able to repair BPDE-induced DNA damage since lower repair capacity levels were calculated compared to their mothers although statistical significance was not reached. Assessment of repair capacity in combination with genotypes will provide important information to support preventive strategies in neonatal care and to define science based exposure limits for pregnant women and children.

Bulky dna adducts in cord blood, maternal fruit-and-vegetable consumption, and birth weight in a European mother-child study (NewGeneris)

BACKGROUND

Tobacco-smoke, airborne, and dietary exposures to polycyclic aromatic hydrocarbons (PAHs) have been associated with reduced prenatal growth. Evidence from biomarker-based studies of low-exposed populations is limited. Bulky DNA adducts in cord blood reflect the prenatal effective dose to several genotoxic agents including PAHs.

OBJECTIVES

We estimated the association between bulky DNA adduct levels and birth weight in a multicenter study and examined modification of this association by maternal intake of fruits and vegetables during pregnancy.

METHODS

Pregnant women from Denmark, England, Greece, Norway, and Spain were recruited in 2006-2010. Adduct levels were measured by the 32P-postlabeling technique in white blood cells from 229 mothers and 612 newborns. Maternal diet was examined through questionnaires.

RESULTS

Adduct levels in maternal and cord blood samples were similar and positively correlated (median, 12.1 vs. 11.4 adducts in 108 nucleotides; Spearman rank correlation coefficient = 0.66, p < 0.001). Cord blood adduct levels were negatively associated with birth weight, with an estimated difference in mean birth weight of -129 g (95% CI: -233, -25 g) for infants in the highest versus lowest tertile of adducts. The negative association with birth weight was limited to births in Norway, Denmark, and England, the countries with the lowest adduct levels, and was more pronounced in births to mothers with low intake of fruits and vegetables (-248 g; 95% CI: -405, -92 g) compared with those with high intake (-58 g; 95% CI: -206, 90 g).

CONCLUSIONS

Maternal exposure to genotoxic agents that induce the formation of bulky DNA adducts may affect intrauterine growth. Maternal fruit and vegetable consumption may be protective.

Malondialdehyde-deoxyguanosine and bulky DNA adducts in schoolchildren resident in the proximity of the Sarroch industrial estate on Sardinia Island, Italy

Air quality is a primary environmental concern in highly industrialised areas, with potential health effects in children residing nearby. The Sarroch industrial estate in Cagliari province, Sardinia Island, Italy, hosts the world's largest power plant and the second largest European oil refinery and petrochemical park. This industrial estate produces a complex mixture of air pollutants, including benzene, heavy metals and polycyclic aromatic hydrocarbons. Thus, we conducted a cross-sectional study to evaluate the prevalence of malondialdehyde-deoxyguanosine adducts in the nasal epithelium of 75 representative children, aged 6-14 years, attending primary and secondary schools in Sarroch in comparison with 73 rural controls. Additionally, the levels of bulky DNA adducts were analysed in a subset of 62 study children. DNA damage was measured by (32)P-postlabelling methodologies. The air concentrations of benzene and ethyl benzene were measured in the school gardens of Sarroch and a rural village by diffusive samplers. Outdoor measurements were also performed in other Sarroch areas and in the proximity of the industrial estate. The outdoor levels of benzene and ethyl benzene were significantly higher in the school gardens of Sarroch than in the rural village. Higher concentrations were also found in other Sarroch areas and in the vicinity of the industrial park. The mean levels of malondialdehyde-deoxyguanosine adducts per 10(8) normal nucleotides ± standard error (SE) were 74.6±9.1 and 34.1±4.4 in the children from Sarroch and the rural village, respectively. The mean ratio was 2.53, 95% confidence interval (CI): 1.71-2.89, P < 0.001, versus rural controls. Similarly, the levels of bulky DNA adducts per 10(8) normal nucleotides ± SE were 2.9±0.4 and 1.6±0.2 in the schoolchildren from Sarroch and the rural village, respectively. The means ratio was 1.90, 95% CI: 1.25-2.89, P = 0.003 versus rural controls. Our study indicates that children residing near the industrial estate have a significant increment of DNA damage.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and risk of oral cleft-affected pregnancies

OBJECTIVE

To evaluate whether there is an association between maternal occupational exposure to polycyclic aromatic hydrocarbons and oral clefts in offspring. This is the first human study of polycyclic aromatic hydrocarbons and clefts of which the authors are aware.

DESIGN

Case-control study.

SETTING, PARTICIPANTS

Data for 1997 to 2002 from the National Birth Defects Prevention Study, a large population-based case-control study in the United States, were analyzed. Maternal telephone interviews yielded information on jobs held in the month before through 3 months after conception. Two industrial hygienists independently assessed occupational exposure to polycyclic aromatic hydrocarbons; all jobs rated as exposed or with rating difficulty were reviewed with a third industrial hygienist to reach consensus on all exposure parameters. Logistic regression estimated crude and adjusted odds ratios with 95% confidence intervals for cleft lip with or without cleft palate and cleft palate alone.

RESULTS

There were 2989 controls (3.5% exposed), 805 cases of cleft lip with or without cleft palate (5.8% exposed), and 439 cases of cleft palate alone (4.6% exposed). The odds of maternal occupational exposure to polycyclic aromatic hydrocarbons (any versus none) during pregnancy was increased for cleft lip with or without cleft palate cases as compared with controls (odds ratio, 1.69; 95% confidence interval, 1.18 to 2.40); the odds ratio was 1.47 (95% confidence interval 1.02 to 2.12) when adjusted for maternal education. There was a statistically significant adjusted exposure-response relationship for cleft lip with or without cleft palate (Ptrend = .02). Odd ratios for cleft palate alone were not statistically significant.

CONCLUSIONS

Maternal occupational exposure to polycyclic aromatic hydrocarbons was associated with increased risk of cleft lip with or without cleft palate in offspring.

Levels of PAH-DNA adducts in placental tissue and the risk of fetal neural tube defects in a Chinese population

We examined the relationship between PAH-DNA adduct levels in the placental tissue, measured by a highly sensitive (32)P-postlabeling assay, and the risk of fetal neural tube defects (NTDs). We further explored the interaction between PAH-DNA adducts and placental PAHs with respect to NTD risk. Placental tissues from 80 NTD-affected pregnancies and 50 uncomplicated normal pregnancies were included in this case-control study. Levels of PAH-DNA adducts were lower in the NTD group (8.12 per 10(8) nucleotides) compared to controls (9.92 per 10(8) nucleotides). PAH-DNA adduct concentrations below the median was associated with a 3-fold increased NTD risk. Women with a low PAH-DNA adduct level in concert with a high placental PAH level resulted in a 10-fold elevated risk of having an NTD-complicated pregnancy. A low level of placental PAH-DNA adducts was associated with an increased risk of NTDs; this risk increased dramatically when a low adduct level was coupled with a high placental PAH concentration.

Maternal environmental exposure, infant GSTP1 polymorphism, and risk of isolated congenital heart disease

The GSTP1 gene, highly expressed early in fetal life, is the most abundant phase 2 xenobiotic metabolism enzyme in a human placenta. Fetal inherited GSTP1 Ile105Val polymorphism may modify the metabolism and excretion of xenobiotics from fetal tissue and increase the risk of congenital heart disease (CHD). This study aimed to analyze the joint effects of GSTP1 genetic polymorphism (Ile105Val) and maternal environmental exposure on CHD risk. Within a case-control design, a total of 190 children with CHD (104 boys age 4 ± 5.6 years) and 190 healthy children (114 newborn boys) were genotyped for the GSTP1 Ile105Val polymorphism. Mothers completed a structured questionnaire on the demographics as well as the preconceptional and lifestyle exposures. A higher frequency of mothers of children with CHD (38 %) reported a positive history of exposure to toxicants (occupational and environmental) than mothers of healthy children (23 %) (p = 0.0013). Logistic regression analysis showed that maternal occupational and environmental exposures increased the risk of CHD (odds ratio, 2.6; 95 % confidence interval, 1.6-4.2; p < 0.0001). No significant differences in Ile105Val genotype frequencies were observed between the children with CHD and the healthy children (p = 0.9). Furthermore, case-control analysis showed no evidence of significant interaction between the maternal exposures and GSTP1 polymorphism. Maternal exposure to toxicants increased the risk of children with CHD. However, fetal GSTP1 Ile105Val polymorphism did not increase the risk of CHD.

DNA and protein adducts in human tissues resulting from exposure to tobacco smoke

Tobacco smoke contains a variety of genotoxic carcinogens that form adducts with DNA and protein in the tissues of smokers. Not only are these biochemical events relevant to the carcinogenic process, but the detection of adducts provides a means of monitoring exposure to tobacco smoke. Characterization of smoking-related adducts has shed light on the mechanisms of smoking-related diseases and many different types of smoking-derived DNA and protein adducts have been identified. Such approaches also reveal the potential harm of environmental tobacco smoke (ETS) to nonsmokers, infants and children. Because the majority of tobacco-smoke carcinogens are not exclusive to this source of exposure, studies comparing smokers and nonsmokers may be confounded by other environmental sources. Nevertheless, certain DNA and protein adducts have been validated as biomarkers of exposure to tobacco smoke, with continuing applications in the study of ETS exposures, cancer prevention and tobacco product legislation. Our article is a review of the literature on smoking-related adducts in human tissues published since 2002.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and risk of neural tube defect-affected pregnancies

BACKGROUND

This study evaluated whether there is an association between maternal occupational exposure to polycyclic aromatic hydrocarbons (PAHs) and neural tube defects (NTDs) in offspring. This is the first such study of which the authors are aware.

METHODS

Data were analyzed from 1997 to 2002 deliveries in the National Birth Defects Prevention Study, a large population-based case-control study in the United States. Maternal interviews yielded information on jobs held in the month before through 3 months after conception. Three industrial hygienists blinded to case or control status assessed occupational exposure to PAHs. Crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using unconditional logistic regression.

RESULTS

Of the 520 mothers of children with NTDs, 5.0% were classified as exposed to occupational PAHs, as were 3.5% of the 2989 mothers of controls. The crude OR for PAH exposure was 1.43 (95% CI, 0.92-2.22) for any NTD and 1.71 (95% CI, 1.03-2.83) for spina bifida. Adjusted ORs were smaller in magnitude and not significant. Among women who were normal weight or underweight, the crude OR for spina bifida was 3.13 (95% CI, 1.63-6.03) and adjusted OR was 2.59 (95% CI, 1.32-5.07). Based on estimated cumulative exposure, a statistically significant dose-response trend was observed for spina bifida; however, it was attenuated and no longer significant after adjustment.

CONCLUSION

Maternal occupational exposure to PAHs may be associated with increased risk of spina bifida in offspring among women who are normal weight or underweight. Other comparisons between PAHs and NTDs were consistent with no association.

Maternal diet and dioxin-like activity, bulky DNA adducts and micronuclei in mother-newborns

Maternal diet can contribute to carcinogenic exposures and also modify effects of environmental exposures on maternal and fetal genetic stability. In this study, associations between maternal diet and the levels of dioxin-like plasma activity, bulky DNA adducts in white blood cells and micronuclei (MN) in lymphocytes from mother to newborns were examined. From 98 pregnant women living in the greater area of Copenhagen, Denmark in 2006-2007, maternal peripheral blood and umbilical cord blood were collected, together with information on health, environmental exposure and lifestyle. Maternal diet was estimated on the basis of maternal food frequency questionnaire (FFQ) completed by the end of pregnancy. Biomarkers were detected in paired blood samples through the dioxin-responsive chemical-activated luciferase expression (CALUX)(®) bioassay, (32)P-postlabelling technique and cytokinesis-block MN assay. Maternal preference for meats with dark surface were significantly associated with higher bulky DNA adducts in both maternal (β 95%CI; 0.46 (0.08, 0.84)) and cord blood (β 95%CI; 0.46 (0.05, 0.86)) before and after adjustment for potential confounders. No other significant associations between the 18 dietary variables and the biomarkers measured in maternal and fetal samples were identified. The present study suggests that maternal intake of meats with dark surface contributes to the bulky DNA adduct levels in maternal and umbilical cord blood. Relationship between food preparation and bulky DNA adducts appear to be captured by a FFQ while potential associations for other biomarkers might be more complex or need larger sample size.

Development and validation of a direct sandwich chemiluminescence immunoassay for measuring DNA adducts of benzo[a]pyrene and other polycyclic aromatic hydrocarbons

We have developed and validated a sandwich chemiluminescence immunoassay (SCIA) which measures polycyclic aromatic hydrocarbon (PAH)-DNA adducts combining high throughput and adequate sensitivity, appropriate for evaluation of adduct levels in human population studies. Fragmented DNA is incubated with rabbit antiserum elicited against DNA modified with r7,t8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) and subsequently trapped by goat anti-rabbit IgG bound to a solid surface. Anti-single-stranded (ss) DNA antibodies binds in a quantity proportional to the adduct levels and is detected by chemiluminescence. The BPDE-DNA SCIA has a limit of detection of 3 adducts per 10(9) nucleotides with 5 μg DNA per well. We have validated the BPDE-DNA SCIA using DNA modified in vitro, DNA from benzo[a]pyrene (BP)-exposed cultured cells and mice. The levels of adduct measured by SCIA were lower (30-60%) than levels of bulky DNA adducts measured in the same samples by (32)P-postlabelling. The BPDE-DNA SCIA also detected adducts produced in vivo by PAHs other than BP. When blood DNA samples from maternal/infant pairs were assayed by BPDE-DNA SCIA, the adduct levels obtained were significantly correlated. However, there was no correlation between (32)P-postlabelling and SCIA values for the same samples. The SCIA can be extended to any DNA adduct and is expected to provide, when fully automated, a valuable high-throughput approach in large-scale population studies.

Preterm newborns show slower repair of oxidative damage and paternal smoking associated DNA damage

Newborns have to cope with hypoxia during delivery and a sudden increase in oxygen at birth. Oxygen will partly be released as reactive oxygen species having the potential to cause damage to DNA and proteins. In utero, increase of most (non)-enzymatic antioxidants occurs during last weeks of gestation, making preterm neonates probably more sensitive to oxidative stress. Moreover, it has been hypothesized that oxidative stress might be the common etiological factor for certain neonatal diseases in preterm infants. The aim of this study was to assess background DNA damage; in vitro H(2)O(2) induced oxidative DNA damage and repair capacity (residual DNA damage) in peripheral blood mononucleated cells from 25 preterm newborns and their mothers. In addition, demographic data were taken into account and repair capacity of preterm was compared with full-term newborns. Multivariate linear regression analysis revealed that preterm infants from smoking fathers have higher background DNA damage levels than those from non-smoking fathers, emphasizing the risk of paternal smoking behaviour for the progeny. Significantly higher residual DNA damage found after 15-min repair in preterm children compared to their mothers and higher residual DNA damage after 2 h compared to full-term newborns suggest a slower DNA repair capacity in preterm children. In comparison with preterm infants born by caesarean delivery, preterm infants born by vaginal delivery do repair more slowly the in vitro induced oxidative DNA damage. Final impact of passive smoking and of the slower DNA repair activity of preterm infants need to be confirmed in a larger study population combining transgenerational genetic and/or epigenetic effects, antioxidant levels, genotypes, repair enzyme efficiency/levels and infant morbidity.

Deregulation of gene expression induced by environmental tobacco smoke exposure in pregnancy

INTRODUCTION

Environmental tobacco smoke (ETS) exposure in pregnant women may have detrimental effects such as spontaneous abortion, lower birth weight, stillbirth, and reduced infant lung function. To extend our knowledge on the molecular effects of tobacco smoke exposure in pregnancy, we analyzed transcriptome alterations in passive smokers (PS) and compared them with those in active smokers (AS).

METHODS

Using Illumina Expression Beadchips with 24,526 transcript probes, gene expression patterns were assayed in placentas from PS (N = 25) exposed to ETS throughout pregnancy and nonexposed (NS) counterparts (N = 34) and in cord blood cells from their newborns. ETS exposure was evaluated by questionnaire disclosure and cotinine measurement in maternal and cord blood.

RESULTS

A total of 158 genes were significantly deregulated in the placentas of PS compared with NS. These genes were associated with the extracellular matrix, apoptosis, placental function, blood clotting, response to stress, and lipid metabolism. Cord blood of the newborns of PS displayed differential expression of 114 genes encoding mainly adhesion molecules and regulators of immunologic response. A comparison of the affected pathways between PS and AS indicated that ETS exposure and active smoking in pregnancy partly employ the same molecular mechanisms.

CONCLUSIONS

This study demonstrates that even low dose exposure to ETS during pregnancy leads to significant deregulation of transcription in placental and fetal cells. These data suggest that the effect of ETS on the fetus is primarily indirect, mediated via deregulation of placental functions.

Micronuclei levels in mothers and their newborns from regions with different types of air pollution

The aim of this study was to analyze genetic damage in human lymphocytes measured using automated image analysis of micronuclei (MN) in a group of 178 mothers and their newborns from two locations in the Czech Republic. The concentrations of benzo[a]pyrene (B[a]P), particulate matter of aerodynamic diameter <2.5 μm (PM2.5) and benzene were measured by stationary monitoring in the winter season of 2008/2009 in the capital city of Prague and in Ceske Budejovice, a regional city in a rural area. The 3-month mean concentration of B[a]P before delivery was lower in Prague in comparison with Ceske Budejovice: 1.9 ± 0.5ng/m³ vs. 3.2 ± 0.2ng/m³ (p<0.001). The opposite trend was found for PM2.5 and benzene: 27.0 ± 2.5μg/m³ and 2.5 ± 0.5μg/m³ vs. 24.5 ± 0.7μg/m³ and 2.1 ± 0.8μg/m³ (p<0.001) for Prague vs. Ceske Budejovice, respectively. The average age of the mothers was 31 years (range, 18-49 years). The frequencies of MN per 1000 binucleated cells were 8.35 ± 3.06 vs. 6.47 ± 2.35 (p<0.001) for mothers from Prague and Ceske Budejovice, respectively, and 2.17 ± 1.32 vs. 3.82 ± 2.43 (p<0.001) for newborns from Prague and Ceske Budejovice, respectively. Other factors, including vitamin intake, exposure to tobacco smoke, body mass index (BMI) before pregnancy, the education level of the mothers and the impact of the mothers' and fathers' ages were analyzed in our study. The results suggest that the different sensitivity of the study groups to various mixtures of carcinogenic pollutants could be affected by significant differences in lifestyle factors. Possible higher genetic damage was analyzed in newborns of smoking mothers, and the birth weight of this group was 7.4% lower (p<0.05) in comparison with the newborns of nonsmoking mothers. No impact of the age of the mothers or fathers on MN frequency in the newborns was observed.

Maternal tobacco use is associated with increased markers of oxidative stress in the placenta

OBJECTIVE

We sought to extend our prior observations and histopathologically characterize key metabolic enzymes (CYP1A1) with markers of oxidative damage in the placental sections from smokers.

STUDY DESIGN

Placental specimens were collected from term singleton deliveries from smokers (n = 10) and nonsmokers (n = 10) and subjected to a detailed histopathological examination. To quantify the extent of oxidative damage, masked score-graded (0-6) histopathology against 4-hydroxy-2-nonenal (4-HNE) and 8-hydroxydeoxyguanisine (8-OHdG) was performed. Minimal significance (P < .05) was determined with a Fisher's exact and a 2-tailed Student t test as appropriate.

RESULTS

We observed a significant increase in the presence of syncytial knots in placentas from smokers (70% vs 10%, P = .02). These gross observations were accompanied by a significant aberrant placental aromatic hydrocarbon metabolism (increased CYP1A1, 4.4 vs 2.1, P = .002) in addition to evidence of oxidative damage (4-HNE 3.4 vs 1.1, P = .00005; 8-OHdG 4.9 vs 3.1, P = .0038).

CONCLUSION

We observed a strong association between maternal tobacco use and aberrant placental metabolism, syncytial knot formation, and multiple markers of oxidative damage.

Placental transfer and DNA binding of benzo(a)pyrene in human placental perfusion

Benzo(a)pyrene (BP) is the best studied polycyclic aromatic hydrocarbon, classified as carcinogenic to humans. The carcinogenic metabolite, benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), binds covalently to DNA. The key enzyme in this metabolic reaction is CYP1A1, which has also been found in placenta and human trophoblastic cells. By using human placental perfusion we confirmed that BP added to the maternal circulation in concentrations of 0.1 and 1 microM reaches fetal compartment but somewhat slower than the freely diffusible reference substance antipyrine. A well-known P-glycoprotein (ABCB1/P-gp) antagonist verapamil did not affect the transfer more than it did in the case of antipyrine, indicating that ABCB1/P-gp does not have a role in BP transfer. In one of the two placentas perfused for 6 h with the higher concentration of BP (1 microM) BPDE specific DNA adducts were found in placental tissue after the perfusion, but not before. The ability of human trophoblastic cells to activate BP to BPDE-DNA adducts was confirmed in human trophoblastic BeWo cells. This study shows that maternal exposure to BP leads to the exposure of the fetus to BP and/or its metabolites and that placenta itself can activate BP to DNA adducts.

Exposure to polycyclic aromatic hydrocarbons and missed abortion in early pregnancy in a Chinese population

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are formed during incomplete burning of fossil fuels, wood, and tobacco products. High PAH exposure has been associated with low birth weight, intrauterine growth restriction, and preterm birth, but little is known about its impact on adverse outcomes in early pregnancy such as in-utero fetal death.

OBJECTIVES

To examine associations between exposure to PAHs and missed abortion in which the embryo has died but a miscarriage has not yet occurred during early pregnancy in a Chinese population in Tianjin.

METHODS

A case-control study was conducted from April to November, 2007 in Tianjin, China. Cases experienced a missed abortion while controls underwent elective abortions before 14weeks of pregnancy. Eighty-one cases were recruited from four hospitals, with the same number of controls matched on hospital, maternal age (+/-8years), gravidity (1 or >1), and gestational age (+/-30days). Two maternal measures of PAH exposures were obtained based on benzo[a]pyrene (BaP) DNA adducts in 1) aborted tissues and 2) maternal blood (for a subset of subjects). In addition, proxy measures for PAH exposures from different sources were derived from maternal interviews.

RESULTS

In conditional logistic regression analyses, we estimated more than 4-fold increase in risk of having experienced a missed abortion in women with above the median levels of blood BaP-DNA adducts (adjusted OR=4.27; 95% CI, 1.41-12.99); but no increase with adduct levels in aborted tissues (adjusted OR=0.76; 95% CI, 0.37-1.54). BaP-DNA adduct levels in maternal blood and aborted tissues were poorly correlated (r=-0.12; n=102). Missed abortion risk also was higher among women reporting traffic congestion near the residence, commuting by walking, and performing regular cooking activities during pregnancy.

CONCLUSION

High levels of maternal PAH exposures may contribute to an increased risk of experiencing a missed abortion during early pregnancy.