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In utero exposure to maternal smoking is associated with DNA methylation alterations and reduced neuronal content in the developing fetal brain

ABSTRACT: Background; Intrauterine exposure to maternal smoking is linked to impaired executive function and behavioral problems in the offspring. Maternal smoking is associated with reduced fetal brain growth and smaller volume of cortical grey matter in childhood, indicating that prenatal exposure to tobacco may impact cortical development and manifest as behavioral problems. Cellular development is mediated by changes in epigenetic modifications such as DNA methylation, which can be affected by exposure to tobacco. Results: In this study we sought to ascertain how maternal smoking during pregnancy affects global DNA methylation profiles of the developing dorsolateral prefrontal cortex (DLPFC) during the second trimester of gestation. When DLPFC methylation profiles (Illumina, HM450) of smoking-exposed and unexposed fetuses were compared, no differentially methylated regions (DMRs) passed false discovery correction (FDR ² 0.05). However, the most significant DMRs were hypomethylated CpG Islands within the promoter regions of GNA15 and SDHAP3 of smoking-exposed fetuses. Furthermore, developmental up-regulation of SDHAP3 mRNA was delayed in smoking- exposed fetuses. DMRÕs passing FDR were found by interaction analysis between gestational age and smoking exposure annotated to SYCE3, C21orf56/LSS, SPAG1 and RNU12/POLDIP3. Utilizing established methods to estimate cell proportions by DNA methylation, we found that exposed DLPFC samples contained a lower proportion of neurons in samples from fetuses exposed to maternal smoking. We further showed that nicotine impedes the differentiation of neurons in vitro independent of cell death. Conclusions; We found evidence that intrauterine smoking exposure alters the developmental patterning of DNA methylation and gene expression and is associated with reduced mature neuronal content, effects that are likely driven by nicotine.

ORGANISM(S): Homo sapiens

PROVIDER: GSE90871 | GEO | 2017/02/19

SECONDARY ACCESSION(S): PRJNA356257

REPOSITORIES: GEO

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Project description:Besides its well-known effects increasing predisposition to oral cancer, cigarette smoke (CS) exposure is an important risk factor for many conditions including periodontal diseases, gingivitis and other benign mucosal disorders. Smoking cessation remains the most effective approach for minimizing risk of smoking-related diseases. However, reduction of harmful constituents by heating rather than combusting tobacco, without modifying the amount of nicotine, is a promising new paradigm in harm reduction. In this study we compared effects of exposure to aerosol derived from a candidate modified risk tobacco product, the tobacco heating system (THS) 2.2, with those of conventional smoke generated from the 3R4F reference cigarette. Human organotypic oral epithelial tissue cultures (EpiOralï¾, MatTek Corporation) were exposed for 28 min to 3R4F CS or THS2.2 aerosol, both diluted with air to comparable nicotine concentrations (0.32 or 0.51 mg nicotine/L aerosol/smoke for 3R4F and 0.31 or 0.46 mg/L for THS2.2). We also tested one higher concentration (1.09 mg/L) of THS2.2. A systems toxicology approach was employed combining cellular assays (i.e. cytotoxicity and cytochrome P450 activity assays), comprehensive molecular investigations of the buccal epithelial transcriptome (mRNA and miRNA) by means of computational network biology, measurements of secreted proinflammatory markers, histopathological analysis. We observed that the impact of 3R4F CS was greater than THS2.2 aerosol in terms of cytotoxicity, morphological tissue alterations and secretion of inflammatory mediators. Analysis of the transcriptomic changes in the exposed oral cultures revealed significant perturbations in various network models such as apoptosis, necroptosis, senescence, xenobiotic metabolism, oxidative stress and nuclear factor (erythroid-derived 2)-like 2 (NFE2L2) signaling. The stress responses following THS2.2 aerosol exposure were markedly decreased and the exposed cultures recovered better as compared with those exposed to 3R4F CS.

Project description:Cigarette smoke (CS) has been reported to increase predisposition to oral cancer and is also recognized as a risk factor for many conditions including periodontal diseases, gingivitis, and other benign mucosal disorders. Smoking cessation remains the most effective approach for minimizing the risk of smoking-related diseases. However, reduction of harmful constituents by heating rather than combusting tobacco, without modifying the amount of nicotine, is a promising new paradigm in harm reduction. In this study, we compared effects of exposure to aerosol derived from a candidate modified risk tobacco product, the tobacco heating system (THS) 2.2, with those of CS generated from the 3R4F reference cigarette. Human organotypic oral epithelial tissue cultures (EpiOral, MatTek Corporation) were exposed for 28 min to 3R4F CS or THS2.2 aerosol, both diluted with air to comparable nicotine concentrations (0.32 or 0.51 mg nicotine/L aerosol/CS for 3R4F and 0.31 or 0.46 mg/L for THS2.2). We also tested one higher concentration (1.09 mg/L) of THS2.2. A systems toxicology approach was employed combining cellular assays (i.e., cytotoxicity and cytochrome P450 activity assays), comprehensive molecular investigations of the buccal epithelial transcriptome (mRNA and miRNA) by means of computational network biology, measurements of secreted proinflammatory markers, and histopathological analysis. We observed that the impact of 3R4F CS was greater than THS2.2 aerosol in terms of cytotoxicity, morphological tissue alterations, and secretion of inflammatory mediators. Analysis of the transcriptomic changes in the exposed oral cultures revealed significant perturbations in various network models such as apoptosis, necroptosis, senescence, xenobiotic metabolism, oxidative stress, and nuclear factor (erythroid-derived 2)-like 2 (NFE2L2) signaling. The stress responses following THS2.2 aerosol exposure were markedly decreased, and the exposed cultures recovered more completely compared with those exposed to 3R4F CS.

Project description:Maternal smoking has a severe negative effect on all stages of pregnancy that in consequence impairs fetal growth and development. Tobacco smoke-related defects are well established at the clinical level; however, little is known about molecular mechanisms underlying these pathological conditions. We thus employed a genomic approach to determine transcriptome alterations induced by maternal smoking in pregnancy. We assayed gene expression profiles in peripheral blood (M) leukocytes and placentas (PL) of pregnant smokers and those without significant exposure, and in cord blood (D) leukocytes of their babies. Comparative analyses defined significant deregulation of 193 genes in M cells, 329 genes in placentas, and 49 genes in D cells of smokers. These genes were mainly involved in xenobiotic metabolism, oxidative stress, inflammation, immunity, hematopoiesis, trophoblast differentiation, and vascularization. Functional annotation of the deregulated genes outlined processes and pathways affected by tobacco smoke. In smoker newborns, we identified several deregulated pathways associated with autoimmune diseases. The study demonstrates a limited ability of placenta to modulate toxic effects of maternal tobacco use at the gene expression level. Blood and placental samples were obtained from 91 women who gave birth to a baby in the Ceske Budejovice Hospital from November 2008 to March 2009. The study was approved by the Local Institutional Review Board. All participants provided written informed consent and completed an extensive questionnaire on pregnancy history (medication, diseases), delivery course, newborn characteristics and life style (smoking, diet, alcohol drinking, area of residency). Only subjects who underwent vaginal delivery were included in the study. Based on smoking history, the women were divided into two groups, “smokers” (N=20) and “non-smokers” (N=52), while passive smokers (N=19) were excluded from the study. Smoking status was further confirmed by detection of excessive plasma levels of cotinine (the major nicotine metabolite) in maternal blood.

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In utero exposure to maternal smoking is associated with DNA methylation alterations and reduced neuronal content in the developing fetal brain

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