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Effect of Smoking on Gene Expression Profile – Overall Mechanism, Impact on Respiratory System Function and Reference to Electronic Cigarettes
Abstract
Cigarette smoke has an crucial impact on transcriptome alteration by its effect on chromatin remodeling and DNA methylation status. The first mechanism is associated with the histone acetylation/deacetylation balance damage as a result of increased activity of NFĸB and lipid peroxidation products, which lead to an increased activity of HATs and DNMTs and reduced HDACs. The second mechanism is connected with direct damaging of DNA by smoke components, activation of downstream repair mechanism and recruitment of DNMTs into the breakage site, “nicotine effect” and carbon monoxide activity on gene transcription and DNA methylation reduction. Cigarette smoking activates oxidative and inflammatory response and leads to uncontrolled structural changes in airways and alters gene expression. Such changes have a characteristic similar to that for COPD patients. Therefore, smoking is determined as a key risk factor for chronic respiratory disease development. Furthermore, electronic cigarettes, an alternative of tobacco cigarettes, also affect gene expression profile, which suggests some similarities in action mechanisms for both conventional and electronic cigarettes. However, there is only a limited number of trials discussing this issue and future investigations are needed.
... A note of caution for mRNA based assays is that mRNA is not stable and needs to be processed and collected in media that stabilize the mRNA; are subject to sample quality; and, mRNAs may have different stability biasing results, with miRNAs being the most stable because of their small size. Kopa and Pawliczak (2018) summarized various human studies for transcriptomics associated with smoking and e-cig use [25], while Silva and Kamens (2020) published a transcriptomics review for smoking [26]. A recent review by Kopa-Stojak and Pawliczak (2022) summarized reported differential miRNA expression in smokers and e-cig users, in experimental animal models and in vitro cell cultures noting that e-cig exposures had lower impacts compared to smoking, but there were some unique effects in the experimental models compared to air controls [27]. ...
... A note of caution for mRNA based assays is that mRNA is not stable and needs to be processed and collected in media that stabilize the mRNA; are subject to sample quality; and, mRNAs may have different stability biasing results, with miRNAs being the most stable because of their small size. Kopa and Pawliczak (2018) summarized various human studies for transcriptomics associated with smoking and e-cig use [25], while Silva and Kamens (2020) published a transcriptomics review for smoking [26]. A recent review by Kopa-Stojak and Pawliczak (2022) summarized reported differential miRNA expression in smokers and e-cig users, in experimental animal models and in vitro cell cultures noting that e-cig exposures had lower impacts compared to smoking, but there were some unique effects in the experimental models compared to air controls [27]. ...
Tobacco research remains a clear priority to improve individual and population health, and has recently become more complex with emerging combustible and noncombustible tobacco products. The use of omics methods in prevention and cessation studies are intended to identify new biomarkers for risk, compared risks related to other products and never use, and compliance for cessation and reinitation. to assess the relative effects of tobacco products to each other. They are important for the prediction of reinitiation of tobacco use and relapse prevention. In the research setting, both technical and clinical validation is required, which presents a number of complexities in the omics methodologies from biospecimen collection and sample preparation to data collection and analysis. When the results identify differences in omics features, networks or pathways, it is unclear if the results are toxic effects, a healthy response to a toxic exposure or neither. The use of surrogate biospecimens (e.g., urine, blood, sputum or nasal) may or may not reflect target organs such as the lung or bladder. This review describes the approaches for the use of omics in tobacco research and provides examples of prior studies, along with the strengths and limitations of the various methods. To date, there is little consistency in results, likely due to small number of studies, limitations in study size, the variability in the analytic platforms and bioinformatic pipelines, differences in biospecimen collection and/or human subject study design. Given the demonstrated value for the use of omics in clinical medicine, it is anticipated that the use in tobacco research will be similarly productive.
... Alcohol consumption is associated with chronic liver diseases, negatively influencing liver fat metabolism [20]. In the meantime, smoking acts on chronic respiratory conditions, through alterations on gene expression and airways function [21]. With respect to physical inactivity, heart and other circulatory conditions are mostly affected due to the direct effect of fitness on cardiorespiratory health, and lastly, unhealthy diets may lead to nutritional imbalances and increased body fat, resulting in obesity and all negative effects of that condition [22,23]. ...
... The findings of the present study were consistent with those found in the literature. Physical inactivity was the behavior that presented the strongest isolated effect and when evaluated in pairs with other behaviors it had the greatest significant effect [21,29]. The combined effect of these same behaviors was evaluated in three European researches [34e36] and an Asian study [28], with similar results, considering that grouped, these factors were associated with a higher risk of mortality, which ranged from 41% [28] to 60% [34]. ...
Backgrounds & Aims
Literature shows that the most studied concurrent risk factors for mortality in elderly individuals are smoking, inadequate diet, alcohol consumption and physical inactivity. The combination of such habits can increase from 3 to 11 times the chance of death. To measure the association between concurrence of behavioral risk factors (BRF) for non-communicable diseases (NCD's) and mortality up to three years among the elderly.
Methods
Cohort study started in 2014 named “COMO VAI?” with community-dwelling aged ≥60 years in Pelotas, Rio Grande do Sul, Brazil. We investigated the deaths from all causes occurred until April 2017. The exposure was defined by the presence of physical inactivity, low-quality diet, alcohol consumption and smoking that composed a score ranging from 0 (none) to 4 (all). Cox proportional hazard regression models were used to evaluate the association between BRF concurrence and mortality.
Results
In 2014, 1,451 elderly people were interviewed, 145 deaths were identified (10%) by April 2017. Higher risk of death was observed for the combinations of physical inactivity + smoking and low-quality diet + physical inactivity. The simultaneous presence of three or more BRF was associated with a nearly six-fold higher risk of death.
Conclusions
Higher mortality during a 3-year period was observed among those with at least three BRF for NCD’s.
... However, the mechanism by which different components of e-cigarette vapor induce DNA damage is unclear. Some mechanistic studies have proposed that e-cigarette vapor produces reactive oxygen species, which cause single-and double-strand breaks, lipid peroxidation, as well as oxidative DNA damage (Anderson et al., 2016;Kopa and Pawliczak, 2018;Zhao et al., 2018). Another indicator of the cytotoxic and genotoxic effects of tobacco is the presence of micronuclei in exfoliated buccal cells collected from smokers (de Geus et al., 2018). ...
It is widely believed that e-cigarettes are less harmful than conventional cigarettes because they have a lower nicotine content. In contrast to this notion, several in vitro studies have evaluated and demonstrated the genotoxicity associated with e-cigarette smoking. However, there is a lack of human studies on the genotoxicity of e-cigarettes. This pilot study evaluated and compared indicators of genotoxicity in e-cigarette users, cigarette smokers, and nonsmokers. A total of 84 healthy participants, including 20 e-cigarette users, 31 cigarette smokers, and 33 nonsmokers, were recruited. Genotoxicity was evaluated by measuring tail moment (TM), tail length (TL), and % tail DNA intensity (%T) using the comet assay as an indicator of DNA damage in blood and detecting micronuclei in buccal cells with the buccal micronucleus (MN) cytome assay. Bivariate analyses showed that there was no significant difference in TM and TL between e-cigarette users and cigarette smokers, but in both groups, the three parameters were significantly higher than that in nonsmokers (p<0.02). In contrast, the frequency of micronuclei in e-cigarette users (40%) was higher than that in cigarette smokers (27.5%). Our findings indicate that e-cigarettes have a similar genotoxic effect to regular cigarettes and, therefore, contradict the notion that e-cigarettes are safer than regular cigarettes.
DNA damage in the blood of nonsmokers (TM=1.96), cigarette smokers (TM=16.3), and e-cigarette users (TM=10) Fullsize Image
... Third, due the limited availability of demographic information provided with GEO datasets, we could not investigate the influence of some potential confounding variables. For instance, we could not explore the effect of smoking or of suicide as a cause of death although such factors have been shown to influence gene expression [94,95] and enhance proinflammatory processes [96,97]. Similarly, the effect of antipsychotic treatment could not be evaluated, while it has been suggested that it may inhibit microglia activation [98]. ...
Besides playing a central role in neuroinflammation, microglia regulate synaptic development and is involved in plasticity. Converging lines of evidence suggest that these different processes play a critical role in schizophrenia. Furthermore, previous studies reported altered transcription of microglia genes in schizophrenia, while microglia itself seems to be involved in the etiopathology of the disease. However, the regional specificity of these brain transcriptional abnormalities remains unclear. Moreover, it is unknown whether brain and peripheral expression of microglia genes are related. Thus, we investigated the expression of a pre-registered list of 10 genes from a core signature of human microglia both at brain and peripheral levels. We included 9 independent Gene Expression Omnibus datasets (764 samples obtained from 266 individuals with schizophrenia and 237 healthy controls) from 8 different brain regions and 3 peripheral tissues. We report evidence of a widespread transcriptional alteration of microglia genes both in brain tissues (we observed a decreased expression in the cerebellum, associative striatum, hippocampus, and parietal cortex of individuals with schizophrenia compared with healthy controls) and whole blood (characterized by a mixed altered expression pattern). Our results suggest that brain underexpression of microglia genes may represent a candidate transcriptional signature for schizophrenia. Moreover, the dual brain-whole blood transcriptional alterations of microglia/macrophage genes identified support the model of schizophrenia as a whole-body disorder and lend weight to the use of blood samples as a potential source of biological peripheral biomarkers.
... Furthermore, in cancer patients, CS has been linked with increased symptoms and decreased chemotherapy efficiency (Gümüş et al., 2008;Peppone et al., 2011). Smoking has a strong effect on the transcriptome and stimulates oxidative and inflammatory responses, alters airway structures, and changes the expression of genes (Kopa & Pawliczak, 2018). Previous investigations have demonstrated that CS significantly changes gene expression profiles in adipose tissue, nasal epithelial cells, buccal cells, whole blood, and lung tissue (Cai et al., 2020;Hijazi et al., 2019;Huan et al., 2016;Na et al., 2015;Tsai et al., 2018). ...
Cigarette smoking (CS) is a crucial modifiable risk of developing several human diseases and cancers. It causes lung, bladder, breast, and esophageal cancers, respiratory disorders, as well as cardiovascular and metabolic diseases. Because of these adverse health effects, continual efforts to decrease the prevalence and toxicity of CS are imperative. Until the past decades, the impacts of natural compounds have been under investigation on the harmful effects of CS. Turmeric ( Curcuma longa ), a rhizomatous herbaceous perennial plant that belongs to the Zingiberaceae family, is the main source of curcumin. This review is an attempt to find out the current knowledge on CS's harmful effects and protective potential of curcumin in the pulmonary, liver, brain, gastrointestinal, and testis organs. According to the present review, simultaneous consumption of curcumin and CS can attenuate CS toxicities including chronic obstructive pulmonary disease, gastrointestinal toxicity, metabolic diseases, testis injury, and neurotoxicity. Moreover, curcumin suppresses carcinogenesis in the skin, liver, lungs, breast, colon, and stomach. Curcumin mediates these protective effects through antioxidant, anti‐inflammatory, anti‐apoptotic, and anti‐carcinogenicity properties.
... As current mood may affect retrospective information of childhood trauma events 33 , analyses were also conducted with and without adjustment for current depressive symptoms. As smoking status has been linked to changes in methylation and gene expression 34 , sensitivity analyses was also conducted adjusting for daily smoking (yes, no). A sample of 465 participants will have 80% power of detecting a medium effect, at a significance criterion of α = 0.05. ...
Exposure to early life trauma increases the risk of psychopathology later in life. Here we investigated if ANK3 mRNA levels influence the relationship between childhood trauma experiences and clinical characteristics in mental disorders. A sample of 174 patients with bipolar disorder and 291 patients with schizophrenia spectrum disorder were included. Patients were diagnosed using the Structured Clinical Interview for DSM-IV, and childhood trauma was assessed using the childhood trauma questionnaire. Age at illness onset and number of psychotic and affective episodes were assessed from interview and medical records. Current depressive symptoms were measured using the calgary depression scale for schizophrenia and the inventory for depressive symptomatology. ANK3 expression was analyzed in whole blood using the Illumina HumanHT-12 v4 Expression BeadChip. Analyses were carried out with the Process adjusted for confounders. Within the total sample, patients with both high ANK3 expression and with the most severe childhood sexual abuse had more manic/hypomanic episodes and an earlier age at onset of the first episode. ANK3 mRNA levels also moderated the relationship between emotional neglect and manic/hypomanic episodes. Our results suggest that ANK3 expression levels moderate the association between specific types of childhood trauma and affective traits in mental disorders.
... Cigarette smoking is a major risk factor for premature death by leading to chronic respiratory diseases, cardiovascular disease, cancer, as well as reproductive system dysfunction (Kopa and Pawliczak, 2018;Onor et al., 2017;Stampfli and Anderson, 2009). Emerging evidence indicates that environmental factors such as antibiotics, diet, alcohol, and smoking influence the human microbiome profiles and alter immune responses (Huang and Shi, 2019). ...
Growing evidence suggests that cigarette smoking alters the salivary microbiome composition and affects the risk of various complex diseases including cancer. However, the potential role of the smoking-associated microbiome in cancer development remains unexplained. Here, the putative roles of smoking-related microbiome alterations in carcinogenesis were investigated by in silico analysis and suggested evidence can be further explored by experimental methodologies. The Disbiome database was used to extract smoking-associated microbial taxa in saliva and taxon set enrichment analysis (TSEA) was conducted to identify the gene sets associated with extracted microbial taxa. We further analyzed the expression profiles of identified genes by using RNA-sequencing data from TCGA and GTEx projects. Associations of the genes with smoking-related phenotypes in cancer datasets were analyzed to prioritize genes for their interplay between smoking-related microbiome and carcinogenesis. Thirty-eight microbial taxa associated with smoking were included in the TSEA and this revealed sixteen genes that were significantly associated with smoking-associated microbial taxa. All genes were found to be differentially expressed in at least one cancer dataset, yet the ELF3 and CTSH were the most common differentially expressed genes giving significant results for several cancer types. Moreover, C2CD3, CTSH, DSC3, ELF3, RHOT2, and WSB2 showed statistically significant associations with smoking-related phenotypes in cancer datasets. This study provides in silico evidence for the potential roles of the salivary microbiome on carcinogenesis. The results shed light on the importance of smoking cessation strategies for cancer management and interventions to stratify smokers for their risk of smoking-induced carcinogenesis.
... Cigarette smoke is an aerosol which contains over 10 15 -10 17 particles per puff. Polycyclic aromatic hydrocarbons, nitrosamines, and other organic noxious substances represent the main components (Kopa and Pawliczak, 2018) and up to 4000 different chemical compounds are released during cigarette consumption or burning (Bourgeois et al., 2016). ...
Health problems associated with the amount of air pollutants are increasing worldwide. Pollution damages not only the lungs; it also has an impact on skin health and is co-responsible for the development of skin diseases.
Anti-pollution products are on the rise in the cosmetic market but so far, there is no established method to directly assess the impact of pollution on the skin and to test the efficacy of anti-pollution products.
To address this problem, two different chambers were developed for the reproducible exposure to realistic air pollutant concentrations. One chamber for the exclusive use of excised skin and hair samples, the second chamber for ex vivo and in vivo measurements. Measurements of nicotine next to the investigated skin area allow conclusions to be drawn on the particle concentration to which the skin is exposed. Electron paramagnetic resonance spectroscopy, which enables the detection of free radicals in different systems, was applied to assess the hazard potential of pollution in the skin. A direct proof of the formation of free radicals in the skin by the model pollutant cigarette smoke could be demonstrated. An additional application of UV irradiation even increased the formation of free radicals in the skin seven-fold (sum parameter). Depending on the question of interest, the use of different spin probes allows various assessments of the radical formation in skin: the amount of radicals but also the antioxidant status of the microenvironment can be estimated.
Using two exposure chambers, the direct formation of oxidative stress by cigarette smoke on ex vivo skin, with and without additional UV exposure, could be reproducibly examined. This measurement method is promising for the assessment of anti-pollution products and could allow a direct causal connection between pollutant, effect on the skin and the protective function of skin care products.
... The archetype is alpha-1-antitrypsin (A1AT) deficiency, but more complex interactions between specific gene loci and environmental factors have been suggested (Cho et al., 2014). CS might affect DNA transcription by epigenetic alterations or by directly damaging DNA by smoke components (Kopa & Pawliczak, 2018). Past RNA-sequencing studies in mice and humans have confirmed that both CS per se and COPD affect the transcriptome in blood and lung tissue (Huan et al., 2016;Jeong et al., 2018;Vishweswaraiah et al., 2018). ...
Cigarette smoke (CS) is the major risk factor for COPD and is linked to cardiopulmonary dysfunction. Exercise training as part of pulmonary rehabilitation is recommended for all COPD patients. It has several physiological benefits, but the mechanisms involved remain poorly defined. Here, we employed transcriptomic profiling and examined lung endothelium to investigate novel interactions between exercise and CS on cardiopulmonary alterations. Mice were exposed to 20 weeks of CS, CS + 6 weeks of high-intensity interval training on a treadmill, or control. Lung and cardiac (left and right ventricle) tissue were harvested and RNA-sequencing was performed and validated with RT-qPCR. Immunohistochemistry assessed pulmonary arteriolar changes. Transcriptome analysis between groups revealed 37 significantly regulated genes in the lung, 21 genes in the left ventricle, and 43 genes in the right ventricle (likelihood-ratio test). Validated genes that showed interaction between exercise and CS included angiotensinogen (p = 0.002) and resistin-like alpha (p = 0.019) in left ventricle, with prostacyclin synthetase different in pulmonary arterioles (p = 0.004). Transcriptomic profiling revealed changes in pulmonary and cardiac tissue following exposure to CS, with exercise training exerting rescue effects. Exercise-regulated genes included angiotensinogen and resistin-like alpha, however, it remains unclear if these represent potential candidate genes or biomarkers that could play a role during pulmonary rehabilitation.
... Cigarette smoke contains a large number of toxic substances, including a large number of oxygen metabolite-derived or reactive oxygen species (ROS), which can directly disrupt this physical barrier, resulting in increased permeability of respiratory epithelial cells and hindering clearance of mucus cilia [28]. Importantly, cigarette smoke could induce oxidative damage to cell membrane lipids through various mechanisms, such as DNA damage, lipid peroxidation, amino acid oxidation, inorganic enzyme cofactor oxidation, etc. [29][30][31]. ...
Cigarette smoke is a complex aerosol containing a large number of compounds with a variety of toxicity and carcinogenicity. Long-term exposure to cigarette smoke significantly increases the risk of a variety of diseases, including chronic obstructive pulmonary disease (COPD) and lung cancer. Epithelial–mesenchymal transition (EMT) is a unique biological process, that refers to epithelial cells losing their polarity and transforming into mobile mesenchymal cells, playing a crucial role in organ development, fibrosis, and cancer progression. Numerous recent studies have shown that EMT is an important pathophysiological process involved in airway fibrosis, airway remodeling, and malignant transformation of COPD. In this review, we summarized the effects of cigarette smoke on the development and progression of COPD and focus on the specific changes and underlying mechanisms of EMT in COPD induced by cigarette smoke. We spotlighted the signaling pathways involved in EMT induced by cigarette smoke and summarize the current research and treatment approaches for EMT in COPD, aiming to provide ideas for potential new treatment and research directions.
... Cigarette smoke is an aerosol which contains over 10 15 -10 17 particles per puff. Polycyclic aromatic hydrocarbons, nitrosamines, and other organic noxious substances represent the main components (Kopa and Pawliczak, 2018) and up to 4000 different chemical compounds are released during cigarette consumption or burning (Bourgeois et al., 2016). ...
The amount of air pollutants is increasing globally and causing serious health problems; according to the World Health Organization, more than 7 million people die each year from air pollution. Pollution not only damages the lining of the lungs; it also affects skin health and has been linked to the development of skin diseases. Promotion of the development of oxidative stress can lead to premature skin aging, impaired skin barrier, pigment disturbances, and cellular damage caused by free radicals. Existing symptoms may also worsen. To date, there is no established method to clearly assess the degree of risk of skin contact or the protective effect of the substances used. With the help of electron paramagnetic resonance (EPR) spectroscopy, a new method was established to assess the potential risk of air pollution in the skin and to verify the effectiveness of products designed to protect the skin. Spin-labeled PCA (3-(carboxy)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy) was used to study free radical formation, with cigarette smoke as a model pollutant. To make the stress effect measurable, UVA light was used as an additional external stressor. In addition, the method of confocal Raman microscopy was applied which allows an assessment without the use of an additional marker and external stressor. For subjecting excised pig ear skin samples reproducibly to cigarette smoke, an exposure chamber for ex vivo and in vivo studies was developed. For quantification of the smoke exposure, the deposit of the nicotine concentration next to the investigated area was used as a marker substance. Initial studies have shown that cigarette smoke promotes the production of free radicals in the skin, and there is a positive correlation between nicotine concentration and free radical production. These results will help to establish a new way to measure pollutant effectiveness and preventive measures.
... (David et al., 2007). Les activités de protéines réparatrices de l'ADN impliquées respectivement dans ces mécanismes, XPC (Xeroderma pigmentosum complementation group C) et OGG1/2 (8-Oxoguanine glycosylase) (Radicella et al., 1997;Sugasawa et al., 1998) En plus des modifications directes du génome, la fumée de cigarette peut aussi être responsable d'altérations de mécanismes épigénétiques (Kopa and Pawliczak, 2018;Zong et al., 2019). En effet, de nombreuses études ont démontré l'existence de modifications épigénétiques chez les fumeurs réguliers. ...
Le tabagisme est responsable de 8 millions de morts par an dans le monde. Le sevrage tabagique est actuellement la seule solution pour endiguer cette mortalité mais il est rendu difficile du fait de l’addiction à la nicotine. Depuis quelques années, de nouveaux dispositifs de délivrance de nicotine sont arrivés sur le marché : la cigarette électronique (e-cig) et le tabac chauffé. ien qu’ils soient généralement perçus comme des alternatives plus saines à la cigarette, leur impact précis sur la santé humaine reste à déterminer.Le premier objectif de cette thèse était d’analyser la composition chimique et la toxicité in vitro des émissions d’e-cig de différentes puissances (un modèle de deuxième génération et un modèle de troisième génération (Modbox) réglé à une puissance faible, Mb18W, ou forte, Mb30W) et du tabac chauffé et de les comparer à la fumée de cigarette. Nous avons pu montrer que le tabac chauffé génère beaucoup moins de composés carbonylés et de HAP que la cigarette, mais bien plus que l’e-cig, quel que soit le modèle. e manière concordante, l’exposition de cellules épithéliales bronchiques humaines (BEAS-2 ) cultivées à l’interface air-liquide aux émissions des différents dispositifs a permis de mettre en évidence que les émissions de tabac chauffé induisent une cytotoxicité réduite par rapport à la fumée de cigarette, mais bien plus élevée que les émissions d’e-cig. De plus, des expositions à 12 bouffées de tabac chauffé ou à 120 bouffées d’e-cig induisent un stress oxydant et la sécrétion de certaines cytokines pro-inflammatoires. Des effets similaires sont observés pour la fumée de cigarette mais seulement après 1 bouffée. e manière intéressante, en ce qui concerne l’e-cig, nous avons pu démontrer que la quantité de composés carbonylés émis et le stress oxydant augmentent avec la puissance du dispositif.Le deuxième objectif de mon projet doctoral consistait à évaluer sur un modèle murin la toxicité respiratoire sur le long terme des émissions d’e-cig de troisième génération. Des souris BALB/c ont été exposées exclusivement par voie nasale pendant 4 jours, 3 mois ou 6 mois aux aérosols de Mb18W ou de Mb30W, ou à la fumée de cigarette. Nos expérimentations in vivo ont montré que, d’une part, les émissions d’e-cig générées à 18 W et 30 W sont responsables de modifications épigénétiques induisant sur le long terme une hyper méthylation de l’ N et la dérégulation de certains mi RN à tous les temps d’exposition, mais que, d’autre part, seules celles générées à 30 W sont capables de provoquer des lésions oxydatives de l’ N, sans pour autant aboutir à des aberrations chromosomiques ou des mutations géniques. Les données transcriptomiques obtenues après 6 mois d’exposition aux aérosols d’e-cig ont mis en évidence la dérégulation de plusieurs voies de signalisation impliquées notamment dans la réponse inflammatoire, le stress oxydant et le métabolisme de composés carbonylés et, en particulier, des métabolites du propylène glycol. Cependant, le faible nombre de gènes impactés dans chacune de ces voies ne garantit pas que les dérégulations observées aient un réel impact biologique. Par comparaison, la fumée de cigarette a induit, dans les mêmes conditions d’exposition, la dérégulation d’un nombre plus important de voies de signalisation, notamment en lien avec l’inflammation et le métabolisme des H P, et impliquant chacune un nombre de gènes plus conséquent.Globalement, nos analyses chimiques et in vitro suggèrent que les émissions de tabac chauffé sont moins toxiques que la fumée de cigarette conventionnelle mais bien plus nocives que celles des e-cig, quelle que soit leur puissance. Par ailleurs, les expérimentations in vivo décrites dans ce travail n’ont pas permis de mettre en évidence une toxicité avérée des émissions d’e-cig sur le long terme [...]
... Smoking-induced differential gene expression has been well-documented in previous studies. In fact, smoking has a characteristic impact on the transcriptome, as it activates inflammatory and oxidative responses, changes airway structures, and alters gene expression across tissue types [9]. Previous studies have shown that cigarette smoking significantly alters the gene expression profiles of adipose tissue, buccal cells, nasal epithelial cells, lung tissue, and whole blood [10][11][12][13][14]. ...
Background
Cigarette smoking is the leading preventable cause of death worldwide, and it is the most common cause of oral cancers. This study aims to provide a deeper understanding of the molecular pathways in the oral cavity that are altered by exposure to cigarette smoke.
Methods
The gene expression dataset (accession number GSE8987, GPL96) of buccal mucosa samples from smokers ( n = 5) and never smokers ( n = 5) was downloaded from The National Center for Biotechnology Information's (NCBI) Gene Expression Omnibus (GEO) repository. Differential expression was ascertained via NCBI’s GEO2R software, and Ingenuity Pathway Analysis (IPA) software was used to perform a pathway analysis.
Results
A total of 459 genes were found to be significantly differentially expressed in smoker buccal mucosa ( p < 0.05). A total of 261 genes were over-expressed while 198 genes were under-expressed. The top canonical pathways predicted by IPA were nitric oxide and reactive oxygen production at macrophages, macrophages/fibroblasts and endothelial cells in rheumatoid arthritis, and thyroid cancer pathways. The IPA upstream analysis predicted that the TP53, APP, SMAD3, and TNF proteins as well as dexamethasone drug would be top transcriptional regulators.
Conclusions
IPA highlighted critical pathways of carcinogenesis, mainly nitric oxide and reactive oxygen production at macrophages, and confirmed widespread injury in the buccal mucosa due to exposure to cigarette smoke. Our findings suggest that cigarette smoking significantly impacts gene pathways in the buccal mucosa and may highlight potential targets for treating the effects of cigarette smoking.
... The components of cigarette smoke can affect transcriptome alteration through chromatin remodelling and DNA methylation in the cells of the respiratory system. These changes are essential on the level of DNA and of specific genes [46]. The use of e-cigarettes can also be expected to have similar harmful effects. ...
A wealth of research has comprehensively documented the harmful effects of traditional cigarette smoking and nicotine on human health. The lower rate of exposure to harmful chemicals and toxic substances offered by alternative electronic smoking devices (e-cigarettes, vaping, etc.) has made these methods of smoking popular, especially among adolescents and young adults, and they are regarded frequently as safer than regular cigarettes. During vaporization of these so-called e-liquids, toxins, carcinogens and various other chemical substances may be released and inhaled by the user. Data on the potential human health effect attendant on exposure to e-vapor are based mainly on animal and in vitro studies. The oral tissues are the first locus of direct interaction with the components of the inhaled vapor. However, the short-term as well as long-term effects of the exposure are not known. The aim of the review is to briefly present data on the effects of the chemical components and toxins of e-cigarette vapor on oral cavity cells and tissues of oral health.
... Our analysis of clinical data suggests that smoking might contribute to elevated expression of TPR (Table F in S1 Text). The underlying mechanism still needs clarification, but is probably associated with changes in DNA methylation status and chromatin remodeling caused by specific tobacco carcinogens [74]. Finally, apart from nuclear export, TPR also participates in transcription regulation, chromatin organization, SUMOylation, mitosis, and telomere length control [75]. ...
The robust proliferation of cancer cells requires vastly elevated levels of protein synthesis, which relies on a steady supply of aminoacylated tRNAs. Delivery of tRNAs to the cytoplasm is a highly regulated process, but the machinery for tRNA nuclear export is not fully elucidated. In this study, using a live cell imaging strategy that visualizes nascent transcripts from a specific tRNA gene in yeast, we identified the nuclear basket proteins Mlp1 and Mlp2, two homologs of the human TPR protein, as regulators of tRNA export. TPR expression is significantly increased in lung cancer tissues and correlated with poor prognosis. Consistently, knockdown of TPR inhibits tRNA nuclear export, protein synthesis and cell growth in lung cancer cell lines. We further show that NXF1, a well-known mRNA nuclear export factor, associates with tRNAs and mediates their transport through nuclear pores. Collectively, our findings uncover a conserved mechanism that regulates nuclear export of tRNAs, which is a limiting step in protein synthesis in eukaryotes.
... Some of the predicted biological functions impacted by these changes are those regulating EPC availability or vascular repair potential. These results shed further mechanistic insight with regards to the origin of vascular pathologies associated with air pollution exposures in humans and add to the growing literature suggesting that environmental exposure to volatiles, metals, and chemicals impact health by inducing gene expression changes in diverse cell and tissue types [64][65][66][67][68]. ...
Exposure to fine particulate matter (PM2.5) air pollution is associated with quantitative deficits of circulating endothelial progenitor cells (EPCs) in humans. Related exposures of mice to concentrated ambient PM2.5 (CAP) likewise reduces levels of circulating EPCs and induces defects in their proliferation and angiogenic potential as well. These changes in EPC number or function are predictive of larger cardiovascular dysfunction. To identify global, PM2.5-dependent mRNA and miRNA expression changes that may contribute to these defects, we performed a transcriptomic analysis of cells isolated from exposed mice. Compared with control samples, we identified 122 upregulated genes and 44 downregulated genes in EPCs derived from CAP-exposed animals. Functions most impacted by these gene expression changes included regulation of cell movement, cell and tissue development, and cellular assembly and organization. With respect to miRNA changes, we found that 55 were upregulated while 53 were downregulated in EPCs from CAP-exposed mice. The top functions impacted by these miRNA changes included cell movement, cell death and survival, cellular development, and cell growth and proliferation. A subset of these mRNA and miRNA changes were confirmed by qRT-PCR, including some reciprocal relationships. These results suggest that PM2.5-induced changes in gene expression may contribute to EPC dysfunction and that such changes may contribute to the adverse cardiovascular outcomes of air pollution exposure.
... Furthermore, smoking affects host innate immunity contributing to structural and functional alterations of respiratory ciliary epithelium and different types of human immune cells (Mehta et al. 2008). Remarkably, CS involves genetic variation leading to changes in gene expression (Kopa and Pawliczak 2018), which contribute to the development of several diseases (Yadav et al. 2017). ...
Human β-defensin (HBD), a member of the antimicrobial peptides, is essential for respiratory epithelial cells’ microbial defense, and is affected by cigarette smoking (CS). Its expression is upregulated by stimulation from microbes or inflammation. Genetic polymorphisms in the HBD-1 gene have been implicated in the development of various smoking-related diseases, including chronic obstructive pulmonary disease and asthma. Thus, we sought to analyze possible associations between HBD-1 single-nucleotide polymorphism (SNP) in HBD-1 gene and CS in ethnic Saudi Arabian subjects. Variants rs1047031 (C/T), rs1799946 (C/T), rs2738047 (C/T), and rs11362 (C/T) were investigated by genotyping 575 blood specimens from males and females, smokers/non-smokers: 288/287. The CT and CT+TT genotypes of rs1799946 presented an ~5-fold increased correlation with CS among the female smokers, compared with the female controls (OR = 5.473, P = 0.02003; and OR = 5.211, P = 0.02028, respectively), an observation similar to rs11362 SNP in female smokers, but with protective effects in TT genotype, compared with the CC reference allele (OR = 0.143, P = 0.04368). In shisha smokers, the heterozygous CT and the CT/TT genotype of rs2738047 polymorphism showed the same results with ~3-fold increased correlation with CS (OR = 2.788; P = 0.03448), compared with the cigarette smokers category. No significant association was shown in genotypic distributions and allelic frequencies of rs1047031. Further investigations, including large study samples, are required to investigate the effects of shisha on human beta-defensin expression and protein levels.
... of comorbidities, less frequency of washing hands, and immunological disadvantage given X-chromosome coding proteins in the immune system [2,43,44], whereas smoking can damage respiratory system [45]. In our meta-analysis, we confirmed overall positive crude associations of CVD, hypertension, and diabetes with severe COVID-19, with pooled relative risk estimates around 3-5. ...
Background:
Whether cardiovascular disease (CVD) and its traditional risk factors predict severe coronavirus disease 2019 (COVID-19) is uncertain, in part, because of potential confounding by age and sex.
Methods:
We performed a systematic review of studies that explored pre-existing CVD and its traditional risk factors as risk factors of severe COVID-19 (defined as death, acute respiratory distress syndrome, mechanical ventilation, or intensive care unit admission). We searched PubMed and Embase for papers in English with original data (≥10 cases of severe COVID-19). Using random-effects models, we pooled relative risk (RR) estimates and conducted meta-regression analyses.
Results:
Of the 661 publications identified in our search, 25 papers met our inclusion criteria, with 76,638 COVID-19 patients including 11,766 severe cases. Older age was consistently associated with severe COVID-19 in all eight eligible studies, with RR >~5 in >60-65 versus <50 years. Three studies showed no change in the RR of age after adjusting for covariate(s). In univariate analyses, factors robustly associated with severe COVID-19 were male sex (10 studies; pooled RR = 1.73, [95% CI 1.50-2.01]), hypertension (8 studies; 2.87 [2.09-3.93]), diabetes (9 studies; 3.20 [2.26-4.53]), and CVD (10 studies; 4.97 [3.76-6.58]). RR for male sex was likely to be independent of age. For the other three factors, meta-regression analyses suggested confounding by age. Only four studies reported multivariable analysis, but most of them showed adjusted RR ~2 for hypertension, diabetes, and CVD. No study explored renin-angiotensin system inhibitors as a risk factor for severe COVID-19.
Conclusions:
Despite the potential for confounding, these results suggest that hypertension, diabetes, and CVD are independently associated with severe COVID-19 and, together with age and male sex, can be informative for predicting the risk of severe COVID-19.
... In vitro studies Cellular viability and integrity Flavour chemicals in e-liquids generate fragmented molecules with oxidative and inflammatory potential [6,49]. Some flavours are cytotoxic [12,50]. ...
Vaping has become increasingly popular over the past decade. This pragmatic review presents the published biological effects of electronic cigarette vapour inhalation with a focus on the pulmonary effects. Special attention has been devoted to providing the documented effects specific to each major ingredient, namely propylene glycol/glycerol, nicotine and flavouring agents. For each ingredient, findings are divided according to the methodology used, being in vitro studies, animal studies and clinical studies. Finally, we provide thoughts and insights on the current state of understanding of the pulmonary effects of vaping, as well as novel research avenues and methodologies.
... However, the biological mechanisms underlying smoking-induced diseases are not completely understood. One suggested mechanism is that smoking induces long-term changes in DNA methylation patterns and gene expression that leads to disease (Kopa & Pawliczak, 2018). ...
Worldwide, smoking remains a threat to public health, causing preventable diseases and premature mortality. Cigarette smoke is a powerful inducer of DNA methylation and gene expression alterations, which have been associated with negative health consequences. Here, we review the current knowledge on smoking-related changes in DNA methylation and gene expression in human blood samples. We identified 30 studies focused on the association between active smoking, DNA methylation modifications, and gene expression alterations. Overall, we identified 1,758 genes with differentially methylated sites (DMS) and differentially expressed genes (DEG) between smokers and nonsmokers, of which 261 were detected in multiple studies (≥4). The most frequently (≥10 studies) reported genes were AHRR, GPR15, GFI1, and RARA. Functional enrichment analysis of the 261 genes identified the aryl hydrocarbon receptor repressor and T cell pathways (T helpers 1 and 2) as influenced by smoking status. These results highlight specific genes for future mechanistic and translational research that may be associated with cigarette smoke exposure and smoking-related diseases. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
... The habit "smoking" is one of the main causes of oxidative stress development in the body. In fact, cigarettes contain over 600 different ingredients, creating more than 7000 chemicals when burned, and inducing up to 10 15 -10 17 free radicals in the aerosol per puff during cigarette smoking [4]. Therefore, it is not surprising that the consumption of cigarettes and other tobacco products is associated with physiological disorders, such as pulmonary diseases, cardiovascular dysfunction, reproductive and developmental effects and insulin resistance [5]. ...
The daily consumption of tobacco products leads to a boost in free radical production in tissues, promoting the risk for malignancies, metabolic alterations and chronic-inflammatory diseases. This study aimed to broaden the knowledge of the status of the antioxidative (AO) system in the skin, compared to the blood, of healthy appearing smokers. Both, the basic status compared to non-smokers and the short-term impact of controlled cigarette consumption in smokers were analyzed. Our study showed that the basic level of the AO system of smokers significantly differed from that of non-smokers. As determined by resonant Raman spectroscopy (RRS), the levels of exogenous AOs were decreased in both, the skin, in vivo (β-carotene and lycopene), and blood plasma (β-carotene only). In contrast, the levels of glutathione (GSH), the prototypical endogenous AO, which were analyzed by fluorimetric assays in cutaneous tape strips and blood plasma, were increased in the skin, although unchanged in the blood of smokers. Elevated cutaneous GSH levels were reflected by an elevated overall radical scavenging activity in the skin, as quantified by non-invasive electron paramagnetic resonance (EPR) spectroscopy. Analysis of the expression of selected stress-associated genes in blood immune cells by quantitative RT-PCR in subgroups of non-smokers and smokers additionally demonstrated the downregulation of AKR1C2 in smokers, and its negative correlation with blood plasma levels of the protective immune mediator interleukin-22, assessed by the ELISA technique. Controlled cigarette consumption did not alter exogenous or endogenous AOs in the skin of smokers, but decreased lycopene levels in blood plasma. Moreover, there was a decline in blood IL-22 levels, while no relevant response of blood cell gene expressions was found after the considered short time. Our data therefore demonstrate a strengthened endogenous AO status in the skin of smokers, which may indicate a long-term adaptation to chronic oxidative stress in this specific organ. While this effect was not clearly visible in the blood, this compartment seems to be useful as an immediate indicator of the body’s AO consumption. Moreover, decreased levels of AKR1C2, which we show for the first time to be expressed in immune cells, may be a candidate marker for long-term smoking. In addition, this study demonstrates that the rate constant of a spin probe decline determined by EPR spectroscopy mainly represents the endogenous AO status of a tissue.
... 3,27,30 Male sex is related to higher prevalence of comorbidities, less frequency of washing hands, and immunological disadvantage given X-chromosome coding proteins in the immune system, 2,31,32 whereas smoking can damage respiratory system. 33 In our meta-analysis, we confirmed overall positive crude associations of CVD, hypertension, and diabetes with severe COVID-19, with pooled relative risk estimates around 3-. CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity. ...
Background
Whether cardiovascular disease (CVD) and its traditional risk factors predict severe coronavirus disease 2019 (COVID-19) is uncertain, in part, because of potential confounding by age and sex.
Methods
We performed a systematic review of studies that explored pre-existing CVD and its traditional risk factors as risk factors of severe COVID-19 (defined as death, acute respiratory distress syndrome, mechanical ventilation, or intensive care unit admission). We searched PubMed and Embase for papers in English with original data (≥10 cases of severe COVID-19). Using random-effects models, we pooled relative risk (RR) estimates and conducted meta-regression analyses.
Results
Of the 661 publications identified in our search, 25 papers met our inclusion criteria, with 76,638 COVID-19 patients including 11,766 severe cases. Older age was consistently associated with severe COVID-19 in all eight eligible studies, with RR >∼5 in >60-65 vs. <50 years. Three studies showed no change in the RR of age after adjusting for covariate(s). In univariate analyses, factors robustly associated with severe COVID-19 were male sex (10 studies; pooled RR=1.73, [95%CI 1.50-2.01]), hypertension (8 studies; 2.87 [2.09-3.93]), diabetes (9 studies; 3.20 [2.26-4.53]), and CVD (10 studies; 4.97 [3.76-6.58]). RR for male sex was likely to be independent of age. For the other three factors, meta-regression analyses suggested confounding by age. Only four studies reported multivariable analysis, but most of them showed adjusted RR ∼2 for hypertension, diabetes, and CVD. No study explored renin-angiotensin system inhibitors as a risk factor for severe COVID-19.
Conclusions
Despite the potential for confounding, these results suggest that hypertension, diabetes, and CVD are independently associated with severe COVID-19 and, together with age and male sex, can be used to inform objective decisions on COVID-19 testing, clinical management, and workforce planning.
... Subsequently, genes regulating cell growth or invasion were upregulated. [8][9][10][11][12] Nicotine can also promote pro-inflammatory signalling in the vasculature that accelerates atherosclerotic plaque formation. 13,14 Expressed in most non-neuronal or somatic cells including lung cells, nACHRs, when activated by nicotine binding, can elicit varied changes in cellular physiology by inciting/modulating downstream intracellular signalling pathways. ...
Nicotine is a major tobacco component and found at circulating concentrations in smokers’ bloodstreams. Although considered a non-carcinogenic substance, nicotine rapidly defuses to tissues after being inhaled, inviting effects on cellular physiology, particularly in the lung. Widespread increased use of nicotine-based e-cigarettes, especially in younger adults, creates an urgent need for improved understanding of nicotine’s potential to impact human health.
Biological and biochemistry methods were used to interrogate the potential for nicotine to weaken the genetic integrity of murine and human-lung epithelial cells.
We demonstrate that nicotine potentiates the growth of the lung epithelial cells in a dose–response fashion. Nicotine elicits an acute increase in reactive oxygen species (ROS), which persists at moderately high levels throughout the duration of nicotine exposure. The aberrant increases in ROS appear to induce ER stress and UPR activation, as reflected by BIP upregulation and PERK phosphorylation. Furthermore, prolonged nicotine exposure interferes with p53 function triggered by sodium arsenite. Unless p53 is suppressed, persistent nicotine exposure does not induce colony formation by lung epithelial cells in soft agar.
The data suggest that nicotine treatment, by perturbing intracellular redox state and altering p53 function, can create a pro-tumorigenic environment in lung epithelium. The results suggest caution in using nicotine replacement therapies and e-cigarettes.
This study analyzed gene expression messenger RNA data, from cases with major depressive disorder (MDD) and controls, using supervised machine learning (ML). We built on the methodology of prior studies to obtain more generalizable/reproducible results. First, we obtained a classifier trained on gene expression data from the dorsolateral prefrontal cortex of post-mortem MDD cases (n = 126) and controls (n = 103). An average area-under-the-receiver-operating-characteristics-curve (AUC) from 10-fold cross-validation of 0.72 was noted, compared to an average AUC of 0.55 for a baseline classifier (p = .0048). The classifier achieved an AUC of 0.76 on a previously unused testing-set. We also performed external validation using DLPFC gene expression values from an independent cohort of matched MDD cases (n = 29) and controls (n = 29), obtained from Affymetrix microarray (vs. Illumina microarray for the original cohort) (AUC: 0.62). We highlighted gene sets differentially expressed in MDD that were enriched for genes identified by the ML algorithm. Next, we assessed the ML classification performance in blood-based microarray gene expression data from MDD cases (n = 1,581) and controls (n = 369). We observed a mean AUC of 0.64 on 10-fold cross-validation, which was significantly above baseline (p = .0020). Similar performance was observed on the testing-set (AUC: 0.61). Finally, we analyzed the classification performance in covariates subgroups. We identified an interesting interaction between smoking and recall performance in MDD case prediction (58% accurate predictions in cases who are smokers vs. 43% accurate predictions in cases who are non-smokers). Overall, our results suggest that ML in combination with gene expression data and covariates could further our understanding of the pathophysiology in MDD.
Purpose of Review
Use of electronic cigarettes (e-cigs) has increased sharply recently although understanding of toxicity is limited, particularly target organ effects. Altered DNA methylation is a reversible response to environmental exposures, including smoking, and may be useful as a biomarker of e-cig harm.
Recent Findings
Among studies examining DNA methylation in blood by smoking status, there is considerable variability in differentially methylated CpGs identified; certain CpGs are consistently found. These include AHRR (aryl hydrocarbon receptor repressor gene), particularly cg05575921, cg0363183 in the F2RL2 gene coding for the protease-activated receptor 4 (PAR-4), and several CpGs in the 2q37.1 genomic region. Differences are found even with short duration and light smoking; effects vary with pack-years and time since quitting among former smokers. For tissues other than blood, data are limited but also indicate altered methylation with smoking.
Summary
DNA methylation changes are a consistent biomarker of smoke exposure. Most studies regarding smoke effects on methylation are of blood cells; further evidence regarding effects of smoke, secondhand smoke, and e-cigs on target tissues for smoking-related diseases are needed. Understanding biological effects of e-cigs is critically important to inform regulation; examination of e-cig effects on DNA methylation can significantly add to evidence-based regulation.
Background
Thymine‐DNA glycosylase (TDG) is an essential DNA‐repair enzyme which works in both epigenetic regulation and genome maintenance. It is also responsible for efficient correction of multiple endogenous DNA lesions which occur commonly in mammalian genomes. Research of genetic variants such as SNPs, resulting in disease, is predicted to yield clinical advancements through the identification of sensitive genetic markers and the development of disease prevention and therapy. To that end, the main objective of the present study is to identify the possible interactions between cigarette smoking and the rs4135050 variant of the TDG gene, situated in the intron position, among Saudi individuals.
Methods
TDG rs4135050 (A/T) was investigated by genotyping 239, and 235 blood specimens were obtained from nonsmokers and smokers of cigarette respectively.
Results
T allele frequency was found which showed a significant protective effect on Saudi male smokers (OR = 0.64, p = 0.0187) compared to nonsmoking subjects, but not in female smokers. Furthermore, smokers aged less than 29 years, the AT and AT+TT genotypes decreased more than four times the risk of initiation of smoking related‐diseases compare to the ancestral AA homozygous genotype. Paradoxically, the AT (OR = 3.88, p = 0.0169) and AT+TT (OR = 2.86, p = 0.0420) genotypes were present at a higher frequency in smoking patients aged more than 29 years as compared to nonsmokers at the same ages.
Conclusion
Depending on the gender and age of patients, TDG rs4135050 may provide a novel biomarker for the early diagnosis and prevention of several diseases caused by cigarette smoking.
Chronic obstructive pulmonary disease (COPD) is a debilitating respiratory disease and one of the leading causes of morbidity and mortality worldwide. It is characterized by persistent respiratory symptoms and airflow limitation due to abnormalities in the lower airway following consistent exposure to noxious particles or gases. Acute exacerbations of COPD (AECOPD) are characterized by increased cough, purulent sputum production, and dyspnea. The AECOPD is mostly associated with infection caused by common cold viruses or bacteria, or co-infections. Chronic and persistent infection by non-typeable Haemophilus influenzae (NTHi), a Gram-negative coccobacillus, contributes to almost half of the infective exacerbations caused by bacteria. This is supported by reports that NTHi is commonly isolated in the sputum from COPD patients during exacerbations. Persistent colonization of NTHi in the lower airway requires a plethora of phenotypic adaptation and virulent mechanisms that are developed over time to cope with changing environmental pressures in the airway such as host immuno-inflammatory response. Chronic inhalation of noxious irritants in COPD causes a changed balance in the lung microbiome, abnormal inflammatory response, and an impaired airway immune system. These conditions significantly provide an opportunistic platform for NTHi colonization and infection resulting in a “vicious circle.” Episodes of large inflammation as the consequences of multiple interactions between airway immune cells and NTHi, accumulatively contribute to COPD exacerbations and may result in worsening of the clinical status. In this review, we discuss in detail the interplay and crosstalk between airway immune residents and NTHi, and their effect in AECOPD for better understanding of NTHi pathogenesis in COPD patients.
E-cigarette use has exploded in the past years, especially among young adults and smokers desiring to quit. While concerns are mostly based on the presence of nicotine and flavors, pulmonary effects of propylene glycol and glycerol inhalation, the main solvents of e-liquid have not been thoroughly investigated. In this preclinical study, mice were exposed 2 h daily for up to 8 weeks to vapors of propylene glycol and/or glycerol generated by an e-cigarette. Lung transcriptome analysis revealed it affected the expression level of genes of the circadian molecular clock, despite causing no inflammatory response. Periodical sacrifices showed that the rhythmicity of these regulatory genes was indeed altered in the lungs, but also in the liver, kidney, skeletal muscle, and brain. E-cigarette exposure also altered the expression of rhythmic genes (i.e., hspa1a and hspa1b), suggesting that alterations to the ‘clock genes’ could translate into systemic biological alterations. This study reveals that the major solvents used in e-cigarettes propylene glycol and glycerol, not nicotine or flavors, have unsuspected effects on gene expression of the molecular clock that are to be taken seriously, especially considering the fundamental role of the circadian rhythm in health and disease.
Prolonged cigarette smoking (CS) causes chronic obstructive pulmonary disease (COPD), a prevalent serious condition that may persist or progress after smoking cessation. To provide insight into how CS triggers COPD, we investigated temporal patterns of lung transcrip-tome expression and systemic metabolome changes induced by chronic CS exposure and smoking cessation. Whole lung RNA-seq data was analyzed at transcript and exon levels from C57Bl/6 mice exposed to CS for 1-or 7 days, for 3-, 6-, or 9 months, or for 6 months followed by 3 months of cessation using age-matched littermate controls. We identified previously unreported dysregulation of pyrimidine metabolism and phosphatidylinositol signaling pathways and confirmed alterations in glutathione metabolism and circadian gene pathways. Almost all dysregulated pathways demonstrated reversibility upon smoking cessation , except the lysosome pathway. Chronic CS exposure was significantly linked with alterations in pathways encoding for energy, phagocytosis, and DNA repair and triggered differential expression of genes or exons previously unreported to associate with CS or COPD, including Lox, involved in matrix remodeling, Gp2, linked to goblet cells, and Slc22a12 and Agpat3, involved in purine and glycerolipid metabolism, respectively. CS-induced lung metabolic pathways changes were validated using metabolomic profiles of matched plasma samples, indicating that dynamic metabolic gene regulation caused by CS is reflected in the plasma metabolome. Using advanced technologies, our study uncovered novel pathways and genes altered by chronic CS exposure, including those involved in pyrimidine metabolism, phosphatidylinositol signaling and lysosome function, highlighting their potential importance in the pathogenesis or diagnosis of CS-associated conditions.
While all forms of tobacco exposure have negative health effects, the significance of exposure to electronic cigarettes (eCig) is not fully understood. Here, we studied the global effects of eCig on the micro RNA (miRNA) transcriptome in human lung epithelial cells. Primary human bronchial epithelial (NHBE) cells differentiated at air-liquid interface were exposed to eCig liquid. Exposure of NHBE to any eCig liquid resulted in the induction of oxidative stress-response genes including GCLM, GCLC, GPX2, NQO1 and HO-1. Vaporization of, and/or the presence of nicotine in, eCig liquid was associated with a greater response. We identified 578 miRNAs dysregulated by eCig exposure in NHBE, and 125 miRNA affected by vaporization of eCig liquid. Nicotine containing eCig vapor displayed the most profound effects upon miRNA expression. We selected 8 miRNAs (29A, 140, 126, 374A, 26A-2, 147B, 941 and 589) for further study. We validated increased expression of multiple miRNAs, including miR126, following eCig exposure. We also found significant reduction in the expression of two miR126 target genes, MYC and MRGPRX3, following exposure. These data demonstrated that eCig exposure has profound effects upon gene expression in human lung epithelial cells, some of which are epigenetically programmed at the level of miRNA regulation.
Carbon monoxide (CO) poisoning causes brain damage, which is attenuated by treatment with hydrogen [1,2], a scavenger selective to hydroxyl radical (OH) [3]. This suggests a role of OH in brain damage due to CO poisoning. Studies have shown strong enhancement of OH production in rat striatum by severe CO poisoning with a blood carboxyhemoglobin (COHb) level >70% due to 3000ppm CO, but not less severe CO poisoning with a blood COHb level at approximately 50% due to 1000ppm CO [4]. Interestingly, 5% O2 causes hypoxia comparable with that by 3000ppm CO and produces much less •OH than 3000ppm CO does . In addition, cAMP production in parallel with OH production [5] might contribute to OH production [6]. It is likely that mechanisms other than hypoxia contribute to brain damage due to CO poisoning [7]. To search for the mechanisms, we examined the effects of 1000ppm CO, 3000ppm CO and 5% O2 on gene expression in rat striatum. All array data have been deposited in the Gene Expression Omnibus (GEO) database under accession number GSE94780.
Background
Among the different tobacco products that are available on the US market, cigarette smoking is shown to be the most harmful and the effects of cigarette smoking have been well studied. US epidemiological studies indicate that non-combustible tobacco products are less harmful than smoking and yet very limited biological and mechanistic information is available on the effects of these alternative tobacco products. For the first time, we characterized gene expression profiling in PBMCs from moist snuff consumers (MSC), compared with that from consumers of cigarettes (SMK) and non-tobacco consumers (NTC). ResultsMicroarray analysis identified 100 differentially expressed genes (DEGs) between the SMK and NTC groups and 46 DEGs between SMK and MSC groups. However, we found no significant differences in gene expression between MSC and NTC. Both hierarchical clustering and principle component analysis revealed that MSC and NTC expression profiles were more similar than to SMK. Random forest classification identified a subset of DEGs which predicted SMK from either NTC or MSC with high accuracy (AUC 0.98). ConclusionsPMBC gene expression profiles of NTC and MSC are similar to each other, while SMK exhibit distinct profiles with alterations in immune related pathways. In addition to discovering several biomarkers, these studies support further understanding of the biological effects of different tobacco products. Trial registrationClinicalTrials.gov. Identifier: NCT01923402. Date of Registration: August 14, 2013. Study was retrospectively registered.
Chromatin modifying enzymes mediate DNA methylation and histone modifications upon recruitment to specific target gene loci in response to various stimuli. The key enzymes that regulate chromatin accessibility for maintenance of modifications in DNA and histones, and for modulation of gene expression patterns in response to cigarette smoke (CS), are not known. We hypothesize that CS exposure alters the gene expression patterns of chromatin modifying enzymes, which then affects multiple downstream pathways involved in the response to CS. We have therefore analyzed chromatin modifying enzyme profiles and validated by quantitative real-time PCR (qPCR). We also performed immunoblot analysis of targeted histone marks in C57BL/6J mice exposed to acute and sub-chronic CS, and of lungs from nonsmokers, smokers, and patients with chronic obstructive pulmonary disease (COPD). We found a significant increase in expression of several chromatin modification enzymes, including DNA methyltransferases, histone acetyltransferases, histone methyltransferases and SET domain proteins, histone kinases and ubiquitinases. Our qPCR validation data revealed a significant down-regulation of Dnmt1, Dnmt3a, Dnmt3b, Hdac2, Hdac4, Hat1, Prmt1, and Aurkb. We identified targeted chromatin histone marks (H3K56ac and H4K12ac) which are induced by CS. Thus, CS-induced genotoxic stress differentially affects the expression of epigenetic modulators that regulate transcription of target genes via DNA methylation and site-specific histone modifications. This may have implications in devising epigenetic-based therapies for COPD and lung cancer.
Background:
Exposure to cigarette smoking can increase the risk of cancers and cardiovascular and pulmonary diseases. However, the underlying mechanisms of how smoking contributes to disease risks are not completely understood. Epigenome-wide association studies (EWASs), mostly in non-Asian populations, have been conducted to identify smoking-associated methylation alterations at individual probes. There are few data on regional methylation changes in relation to smoking. Few data link differential methylation in blood to differential gene expression in lung tissue.
Results:
We identified 108 significant (false discovery rate (FDR) < 0.05) differentially methylated probes (DMPs) and 87 significant differentially methylated regions (DMRs) (multiple-testing corrected p < 0.01) in current compared to never smokers from our EWAS of cotinine-validated smoking in blood DNA from a Korean chronic obstructive pulmonary disease cohort (n = 100 including 31 current, 30 former, and 39 never smokers) using Illumina HumanMethylation450 BeadChip. Of the 108 DMPs (FDR < 0.05), nine CpGs were statistically significant based on Bonferroni correction and 93 were novel including five that mapped to loci previously associated with smoking. Of the 87 DMRs, 66 were mapped to novel loci. Methylation correlated with urine cotinine levels in current smokers at six DMPs, with pack-years in current smokers at six DMPs, and with duration of smoking cessation in former smokers at eight DMPs. Of the 143 genes to which our significant DMPs or DMRs annotated, gene expression levels at 20 genes were associated with pack-years in lung tissue transcriptome data of smokers (Asan Biobank, n = 188).
Conclusions:
Our study of differential methylation in Koreans confirmed previous findings from non-Asian populations and revealed novel loci in relation to smoking. Smoking-related differential methylation in blood is associated with gene expression in lung tissue, an important target of adverse health effects of smoking, supporting the potential functional importance of methylation in smoking-related disease.
Exposure to cigarette smoke is known to result in impaired host defense responses and immune suppressive effects. However, the effects of new and emerging tobacco products, such as e-cigarettes, on the immune status of the respiratory epithelium are largely unknown. We conducted a clinical study collecting superficial nasal scrape biopsies, nasal lavage, urine, and serum from non-smokers, cigarette smokers and e-cigarette users and assessed them for changes in immune gene expression profiles. Smoking status was determined based on a smoking history and a 3-4 week smoking diary and confirmed using serum cotinine and urine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels. Total RNA from nasal scrape biopsies were analyzed using the nCounter® Human Immunology v2 Expression panel. Smoking cigarettes or vaping e-cigarettes resulted in decreased expression of immune-related genes. All genes with decreased expression in cigarette smokers (n=53) were also decreased in e-cigarette smokers. Additionally, vaping e-cigarettes was associated with suppression of in a large number of unique genes (n=305). Furthermore, the e-cigarette users showed a greater suppression of genes common with those changed in cigarette smokers. This was particularly apparent for suppressed expression of transcription factors, such as EGR1, which was functionally associated with decreased expression of 5 target genes in cigarette smokers and 18 target genes in e-cigarette users. Taken together, these data indicate that vaping e-cigarettes is associated with decreased expression of a large number of immune-related genes, which are consistent with immune suppression at the level of the nasal mucosa.
Electronic cigarettes (e-cigarettes), battery-powered devices containing nicotine, glycerin, propylene glycol, flavorings, and other substances, are increasing in popularity. They pose a potential threat to the developing brain, as nicotine is a known neurotoxicant. We hypothesized that exposure to e-cigarettes during early life stages induce changes in central nervous system (CNS) transcriptome associated with adverse neurobiological outcomes and long-term disease states. To test the hypothesis, pregnant C57BL/6 mice were exposed daily (via whole body inhalation) throughout gestation (3 h/day; 5 days/week) to aerosols produced from e-cigarettes either with nicotine (13-16 mg/mL) or without nicotine; following birth, pups and dams were exposed together to e-cigarette aerosols throughout lactation beginning at postnatal day (PND) 4-6 and using the same exposure conditions employed during gestational exposure. Following exposure, frontal cortex recovered from ~one-month-old male and female offspring were excised and analyzed for gene expression by RNA Sequencing (RNA-Seq). Comparisons between the treatment groups revealed that e-cigarette constituents other than nicotine might be partly responsible for the observed biological effects. Transcriptome alterations in both offspring sexes and treatment groups were all significantly associated with downstream adverse neurobiological outcomes. Results from this study demonstrate that e-cigarette exposure during early life alters CNS development potentially leading to chronic neuropathology.
Electronic cigarettes (e-cigarettes) generate an aerosol vapor (e-vapor) thought to represent a less risky alternative to main stream smoke (MSS) of conventional tobacco cigarettes. RNA-seq analysis was used to examine the transcriptomes of differentiated human bronchial epithelial (HBE) cells exposed to air, MSS from 1R5F tobacco reference cigarettes, and e-vapor with and without added nicotine in an in vitro air-liquid interface model for cellular exposure. Our results indicate that while e-vapor does not elicit many of the cell toxicity responses observed in MSS-exposed HBE cells, e-vapor exposure is not benign, but elicits discrete transcriptomic signatures with and without added nicotine. Among the cellular pathways with the most significantly enriched gene expression following e-vapor exposure are the phospholipid and fatty acid triacylglycerol metabolism pathways. Our data suggest that alterations in cellular glycerophopholipid biosynthesis are an important consequences of e-vapor exposure. Moreover, the presence of nicotine in e-vapor elicits a cellular response distinct from e-vapor alone including alterations of cytochrome P450 function, retinoid metabolism, and nicotine catabolism. These studies establish a baseline for future analysis of e-vapor and e-vapor additives that will better inform the FDA and other governmental bodies in discussions of the risks and future regulation of these products.
Cigarette smoking is known to be associated with various kinds of diseases, including atherosclerotic cardiovascular disease, cancer, and chronic obstructive pulmonary disease (COPD). Many of the diseases associated with cigarette smoking are also associated with changes in interleukin-6 (IL-6) expression. In this study, we investigated the role of phospholipase D1 (PLD1) in IL-6 expression induced by cigarette smoke extract (CSE). Treatment with CSE increased PLD1 and IL-6 expressions in human bronchial epithelial (BEAS-2B) cells. In addition, CSE treatment activated PLC, PKC, and MAPK pathway through the Gi protein-coupled receptor. Pertussis toxin (PTX, Gi protein-coupled receptor inhibitor), PAO (PLC inhibitor), Go6976 (PKC inhibitor) and SB203580 (p38MAPK inhibitor) decreased CSE-induced PLD1 expression. The results show that Gi protein, PLC, PKC, and p38MAPK act as upstream regulators of PLD1 in CSE-treated BEAS-2B cells. Moreover, PLD1 siRNA transfection decreased CSE-induced ATF2 phosphorylation and IL-6 expression. In addition, inhibitors of Gi protein, PLC, PKC, and p38MAPK, and ATF2 siRNA transfection decreased CSE-induced IL-6 expression, suggesting that CSE-induced IL-6 expression is regulated via Gi protein/PLC/PKC/p38MAPK/PLD1/ATF2 pathway. Taken together, the results suggest that PLD1 is an important regulator of IL-6 expression induced by CSE in BEAS-2B cells.
Background:
Smoking is a risk factor for many human diseases. DNA methylation has been related to smoking, but genome-wide methylation data on smoking in Chinese is limited.
Objectives:
We aimed to investigate epigenome-wide methylation in relation to smoking in Chinese.
Methods:
We measured the methylation levels at >485,000 CpGs of blood leukocytes using HumanMethylation450 BeadChip and conducted a genome-wide meta-analysis of smoking in a total of 596 Chinese participants. For the smoking-related CpGs, we further evaluated their associations with internal polycyclic aromatic hydrocarbons (PAHs) biomarkers and their correlations with the expression of corresponding genes.
Results:
We identified 318 CpGs whose methylation levels were associated with smoking at genome-wide significance level (false discovery rate < 0.05), among which 161 CpGs annotated to 123 genes were not associated with smoking in recent studies of Europeans and African Americans. Of these smoking-related CpGs, methylation levels at 80 CpGs showed significant correlations with the expression of corresponding genes (including RUNX3, IL6R, PTAFR, ANKRD11, CEP135 and CDH23), and methylation at 15 CpGs were significantly associated with urinary 2-hydroxynaphthalene, the most representative internal monohydroxy-PAHs biomarker for smoking.
Conclusion:
We identified DNA methylation markers associated with smoking in Chinese populations, including some that also were correlated with gene expression. Exposure to naphthalene, a by-product of tobacco smoke, may contribute to smoking-related methylation.
Maternal cigarette smoking during pregnancy remains one of the most common and preventable causes of fetal growth restriction (FGR), a condition in which a fetus is unable to achieve its genetically determined potential size. Even though epidemiologic evidence clearly links maternal cigarette smoking with FGR, insight into the molecular mechanisms of cigarette smoke-induced FGR is lacking. Here, we performed transcriptional profiling of placentas obtained from smoking mothers who delivered growth-restricted infants and identified secreted frizzled-related protein 1 (sFRP1), an extracellular antagonist of endogenous WNT signaling, as a candidate molecule. sFRP1 mRNA and protein levels were markedly upregulated (~10 fold) in placentas from smoking mothers compared with those from nonsmokers. In pregnant mice, adenovirus-mediated overexpression of sFRP1 led to FGR, increased karyorrhexis in the junctional zone, and decreased proliferation of labyrinthine trophoblasts. Consistent with our hypothesis that placental WNT signaling is suppressed in maternal smokers, we found that exposure to carbon monoxide analogs led to reduced WNT signaling, increased SFRP1 mRNA expression, and decreased cellular proliferation in a trophoblast cell line. Moreover, administration of carbon monoxide analogs to pregnant mice in late gestation led to FGR. In summary, our results indicate that the increased placental expression of sFRP1 seen in smokers impairs fetal growth by inhibiting WNT signaling and trophoblast proliferation.
Many recent epigenetic studies report that cigarette smoking reduces DNA methylation in whole blood at the single CpG site cg19859270 within the GPR15 gene.
Within two independent cohorts, we confirmed the differentially expression of the GPR15 gene when smokers and non-smokers subjects are compared. By validating the GPR15 protein expression at the cellular level, we found that the observed decreased methylation at this site in white blood cells (WBC) of smokers is mainly caused by the high proportion of CD3+GPR15+ expressing T cells in peripheral blood. In current smokers, the percentage of GPR15+ cells among CD3+ T cells in peripheral blood is significantly higher (15.5 ± 7.2 %, mean ± standard deviation) compared to non-smokers (3.7 ± 1.6 %). Treatment of peripheral blood mononuclear cell (PBMC) cultures with aqueous cigarette smoke extract did not induce a higher proportion of this T cell subtype.
Our results underline that DNA hypomethylation at cg19859270 site, observed in WBCs of smokers, did not arise by direct effect of tobacco smoking compounds on methylation of DNA but rather by the enrichment of a tobacco-smoking-induced lymphocyte population in the peripheral blood.
Long term cigarette smoking (LTCS) has an important extrapulmonary toxicity. The aim of the study was to investigate the time dependent effects of cigarette smoke exposure on exercise capacity, markers of systemic inflammation and skeletal muscle structure. Mice were either exposed to mainstream cigarette smoke for 6 hours/day, 5 days/week (Smoke Exposed, SE group) or assigned to the control, unexposed group (Con group). SE Group mice were exposed for 8, 16, 24 and 32 weeks to smoke and unexposed Con mice were used as age matched controls. Exercise capacity was investigated by spiroergometry. Systemic inflammatory status was analyzed by flow cytometry and multiplexed fluorescent immunoassay. For analysis of muscle tissue histological techniques and microarray analysis were used. Mice of the SE group exhibited a lower increase of body mass and a decrease of VO2max (p<0.05). An increase of lymphocyte CD62, ICAM and VCAM expression was found in SE mice (p<0.05). A biphasic trend of protein up- and down-regulation was observed in markers of systemic inflammation and tissue deterioration such as CRP, eotaxin, haptoglobin, M-CSF-1, MIP-1 γ. Thereby, the expression of several chemotactic proteins in plasma correlated with their expression in muscle. A time dependent decrease of muscle mass and oxidative type-I fibers was found (p<0.05). Microarray analysis revealed a SE-induced up-regulation of several pathways of metabolic processes and tissue degradation. Taken together it was found that the loss of exercise capacity and systemic inflammation are early events of SE, which might induce muscular atrophy and loss of oxidative muscle capacity.
Copyright © 2015, American Journal of Physiology - Lung Cellular and Molecular Physiology.
Smoking is the second leading cause of preventable death in the United States. Cohort epidemiological studies have demonstrated that women are more vulnerable to cigarette-smoking induced diseases than their male counterparts, however, the molecular basis of these differences has remained unknown. In this study, we explored if there were differences in the gene expression patterns between male and female smokers, and how these patterns might reflect different sex-specific responses to the stress of smoking. Using whole genome microarray gene expression profiling, we found that a substantial number of oxidant related genes were expressed in both male and female smokers, however, smoking-responsive genes did indeed differ greatly between male and female smokers. Gene set enrichment analysis (GSEA) against reference oncogenic signature gene sets identified a large number of oncogenic pathway gene-sets that were significantly altered in female smokers compared to male smokers. In addition, functional annotation with Ingenuity Pathway Analysis (IPA) identified smoking-correlated genes associated with biological functions in male and female smokers that are directly relevant to well-known smoking related pathologies. However, these relevant biological functions were strikingly overrepresented in female smokers compared to male smokers. IPA network analysis with the functional categories of immune and inflammatory response gene products suggested potential interactions between smoking response and female hormones. Our results demonstrate a striking dichotomy between male and female gene expression responses to smoking. This is the first genome-wide expression study to compare the sex-specific impacts of smoking at a molecular level and suggests a novel potential connection between sex hormone signaling and smoking-induced diseases in female smokers.
Electronic cigarettes (E-cigs) have experienced sharp increases in popularity over the past five years due to many factors, including aggressive marketing, increased restrictions on conventional cigarettes, and a perception that E-cigs are healthy alternatives to cigarettes. Despite this perception, studies on health effects in humans are extremely limited and in vivo animal models have not been generated. Presently, we determined that E-cig vapor contains 7x1011 free radicals per puff. To determine whether E-cig exposure impacts pulmonary responses in mice, we developed an inhalation chamber for E-cig exposure. Mice that were exposed to E-cig vapor contained serum cotinine concentrations that are comparable to human E-cig users. E-cig exposure for 2 weeks produced a significant increase in oxidative stress and moderate macrophage-mediated inflammation. Since, COPD patients are susceptible to bacterial and viral infections, we tested effects of E-cigs on immune response. Mice that were exposed to E-cig vapor showed significantly impaired pulmonary bacterial clearance, compared to air-exposed mice, following an intranasal infection with Streptococcus pneumonia. This defective bacterial clearance was partially due to reduced phagocytosis by alveolar macrophages from E-cig exposed mice. In response to Influenza A virus infection, E-cig exposed mice displayed increased lung viral titers and enhanced virus-induced illness and mortality. In summary, this study reports a murine model of E-cig exposure and demonstrates that E-cig exposure elicits impaired pulmonary anti-microbial defenses. Hence, E-cig exposure as an alternative to cigarette smoking must be rigorously tested in users for their effects on immune response and susceptibility to bacterial and viral infections.
Electronic cigarettes have achieved growing popularity since their introduction onto the European market. They are promoted by manufacturers as healthier alternatives to tobacco cigarettes, however debate among scientists and public health experts about their possible impact on health and indoor air quality means further research into the product is required to ensure decisions of policymakers, health care providers and consumers are based on sound science.
This study investigated and characterised the impact of ‘vaping’ (using electronic cigarettes) on indoor environments under controlled conditions using a 30 m3 emission chamber. The study determined the composition of e-cigarette mainstream vapour in terms of propylene glycol, glycerol, carbonyls and nicotine emissions using a smoking machine with adapted smoking parameters. Two different base recipes for refill liquids, with three different amounts of nicotine each, were tested using two models of e-cigarettes. Refill liquids were analysed on their content of propylene glycol, glycerol, nicotine and qualitatively on their principal flavourings. Possible health effects of e-cigarette use are not discussed in this work.
Electronic cigarettes tested in this study proved to be sources for propylene glycol, glycerol, nicotine, carbonyls and aerosol particulates. The extent of exposure differs significantly for active and passive ‘vapers’ (users of electronic cigarettes). Extrapolating from the average amounts of propylene glycol and glycerol condensed on the smoking machine filter pad to the resulting lung-concentration, estimated lung concentrations of 160 and 220 mg m-3 for propylene glycol and glycerol were obtained respectively. Vaping refill liquids with nicotine concentrations of 9 mg mL-1 led to vapour condensate nicotine amounts comparable to those of low-nicotine regular cigarettes (0.15-0.2 mg). In chamber studies, peak concentrations of 2200 μg m-3 for propylene glycol, 136 μg m-3 for glycerol and 0.6 μg m-3 for nicotine were
reached. Carbonyls were not detected above the detection limits in chamber studies. Particles in the size range of 20 nm to 300 nm constantly increased during vaping activity and reached final peak concentrations of 7 x 106 particles L-1.Moreover, the tested products showed design flaws such as leakages from the cartridge reservoirs.
Possible long term effects of e-cigarettes on health are not yet known. E-cigarettes, the impact of vaping on health and the composition of refill liquids require therefore further research into the product characteristics. The consumers would benefit from harmonised quality and safety improvements of e-cigarettes and refill liquids.
Objective
Maternal cigarette smoking is reportedly associated with miscarriage, fetal growth restriction and placental abruption, and is paradoxically associated with a decreased risk of developing preeclampsia. In the present study, we investigated the gene expression levels of villous tissues in early gestation. We compared the expression levels of the genes related to angiogenesis and apoptosis in the villous tissues obtained from smoking and non-smoking pregnant women.
Materials and Methods
We collected villous tissue samples from 57 women requesting surgical termination due to non-medical reasons at 6–8 weeks of gestation. The maternal cigarette smoking status was evaluated by the level of serum cotinine and patients were divided into active smokers and non-smokers by the serum cotinine level. The placental levels of VEGFA, PGF, FLT1, HIF1A, TP53, BAX and BCL2 mRNA were quantified by real time PCR.
Results
The gene expression level of PGF and HIF1A in the active smoker group was significantly higher than that in the non-smoker group. We did not observe any significant differences in the VEGFA or FLT1 expression between the groups. In active smoker group, the gene expression levels of TP53 and BAX were significantly higher than those in the non-smoker group. The ratio of BAX/BCL2 mRNA in the active smoker group was significantly higher than that in the non-smoker group.
Conclusions
Our findings revealed that smoking might affect the placenta during early pregnancy. Maternal cigarette smoking in early pregnancy may be associated with villus hypoxia, which may influence angiogenesis and apoptosis.
Objective
The risks of cigarette smoking concerning higher systemic disease mortality are lessened by smoking cessation.
Methods
Microarray analysis compared the expression profiles of smokers who were successful and not successful at smoking cessation, with the goal of identifying genes that might serve as potential biomarkers or that might be valuable in elucidating distinct biological mechanisms. The mRNAs were isolated and compared from peripheral leukocytes of six smokers who were successful in cessation and six smokers who failed in smoking cessation.
Results
Two hundred ninety nine genes displayed significantly different expression; 196 genes were up-regulated and 103 genes were down-regulated in the success group compared to the failure group. Twenty four of these genes were identified with biological processes including immunity, cytoskeleton and cell growth/cycle. Real-time PCR confirmed the differential gene expression. The mRNA levels of HEPACAM family member 2 (HEPACAM2) and tropomodulin 1 (TMOD1) were significantly more expressed in the success group, while the mRNA ubiquitin specific peptides 18 (USP18) were significantly less expressed in the success group compared to the failure group.
Conclusion
The results suggest that smoking cessation can modulate cell adhesion and immune response by regulating expression levels of genes, especially HEPACAM2, TMOD1 and USP18, which have an important relationship with smoking cessation.
Towards a systems toxicology-based risk assessment, we investigated molecular perturbations accompanying histopathological changes in a 28-day rat inhalation study combining transcriptomics with classical histopathology. We demonstrated reduced biological activity of a prototypic modified risk tobacco product (pMRTP) compared with the reference research cigarette 3R4F. Rats were exposed to filtered air or to three concentrations of mainstream smoke (MS) from 3R4F, or to a high concentration of MS from a pMRTP. Histopathology revealed concentration-dependent changes in response to 3R4F that were irritative stress-related in nasal and bronchial epithelium, and inflammation-related in the lung parenchyma. For pMRTP, significant changes were seen in the nasal epithelium only. Transcriptomics data were obtained from nasal and bronchial epithelium and lung parenchyma. Concentration-dependent gene expression changes were observed following 3R4F exposure, with much smaller changes for pMRTP. A computational-modeling approach based on causal models of tissue-specific biological networks identified cell stress, inflammation, proliferation, and senescence as the most perturbed molecular mechanisms. These perturbations correlated with histopathological observations. Only weak perturbations were observed for pMRTP. In conclusion, a correlative evaluation of classical histopathology together with gene expression-based computational network models may facilitate a systems toxicology-based risk assessment, as shown for a pMRTP.
Genome-wide association studies (GWAS) and candidate gene studies have identified a number of risk loci associated with the smoking-related disease COPD, a disorder that originates in the airway epithelium. Since airway basal cell (BC) stem/progenitor cells exhibit the earliest abnormalities associated with smoking (hyperplasia, squamous metaplasia), we hypothesized that smoker BC have a dysregulated transcriptome, enriched, in part, at known GWAS/candidate gene loci. Massive parallel RNA sequencing was used to compare the transcriptome of BC purified from the airway epithelium of healthy nonsmokers (n = 10) and healthy smokers (n = 7). The chromosomal location of the differentially expressed genes was compared to loci identified by GWAS to confer risk for COPD. Smoker BC have 676 genes differentially expressed compared to nonsmoker BC, dominated by smoking up-regulation. Strikingly, 166 (25%) of these genes are located on chromosome 19, with 13 localized to 19q13.2 (p<10(-4) compared to chance), including 4 genes (NFKBIB, LTBP4, EGLN2 and TGFB1) associated with risk for COPD. These observations provide the first direct connection between known genetic risks for smoking-related lung disease and airway BC, the population of lung cells that undergo the earliest changes associated with smoking.
Recent genome-wide DNA methylation studies have found a pronounced difference in methylation of the F2RL3 gene (also known as PAR-4) in blood DNA according to smoking exposure. Knowledge on variation of F2RL3 methylation by various degrees of smoking exposure is still very sparse.
We aimed to assess dose-response relationships of current and lifetime active smoking exposure with F2RL3 methylation.
In a large population-based study, blood DNA methylation at F2RL3 was quantified by means of MALDI-TOF mass spectrometry from 3588 participants. Associations of smoking exposure with methylation intensity were examined by multiple linear regression, controlling for potential confounding factors and paying particular attention to dose-response patterns with respect to current and lifetime smoking exposure, as well as time since cessation of smoking.
F2RL3 methylation intensity showed a strong association with smoking status (P < 0.0001), which persisted after controlling for potential confounding factors. Clear inverse dose-response relationships with F2RL3 methylation intensity were seen for both current intensity and lifetime pack-years of smoking. Among former smokers, F2RL3 methylation intensity increased gradually from levels close to those of current smokers for recent quitters to levels close to never smokers for long-term (>20 years) quitters.
F2RL3 methylation is a promising biomarker for both current and long-term past tobacco exposure, and its predictive value for smoking-related diseases warrants further exploration.
Cigarette smoking is the primary etiology of chronic obstructive pulmonary disease (COPD) and a risk factor for both lung and cardiovascular (CV) diseases, which are rarely investigated concomitantly. Although smoking cessation shows clear CV risk benefit, lung-related disease risk remains higher in former smokers than in never smokers. We sought to determine the differential molecular responses of murine respiratory tissues to better understand the toxicity pathways involved in smoking-related disease risk and those related to the benefits of smoking cessation. ApoE(-/-) mice were exposed to mainstream cigarette smoke (CS) or a smoking cessation-mimicking protocol for up to six months and transcriptomics analysis of nasal epithelium and lung parenchyma performed. We supported our gene expression profiling approach with standard lung histopathology and bronchoalveolar lavage fluid (BALF) analysis. Many BALF analytes involved in functions ranging from inflammation to cell proliferation and tissue remodeling were found elevated in BALF. Gene expression levels of these molecules were also increased in lung tissue, suggesting that the inflammatory response was the result of local tissue activation and the contribution of recruited inflammatory cells. Gene set enrichment analysis (GSEA) of expression data from murine lungs and nasal epithelium showed distinct activation patterns of inflammation, complement, and xenobiotic metabolism pathways during CS exposure that were deactivated upon smoking cessation. Pathways involved in cell proliferation and tissue remodeling were activated by CS and progressively deactivated upon smoke exposure cessation. Differential CS-mediated responses of pulmonary and nasal tissues reflect common mechanisms but also the varying degrees of epithelial functional specialization and exposure along the respiratory tract.
Chronic obstructive pulmonary disease (COPD) is caused by exposure to toxic gases and particles, most often cigarette smoke (CS), leading to emphysema, chronic bronchitis, mucus production and a subsequent decline in lung function. The disease pathogenesis is related to an abnormal CS-induced inflammatory response of the lungs. Similar to active (mainstream) smoking second hand (sidestream) smoke exposure severely affects respiratory health. These processes can be studied in vivo in models of CS exposure of mice. We compared the acute inflammatory response of female C57BL/6 mice exposed to two concentrations (250 and 500 mg/m3 total particulate matter) of sidestream and mainstream CS for 3 days and interpreted the biological effects based on physico-chemical differences in the gas and particulate phase composition of CS. Bronchoalveolar lavage fluid was obtained to perform differential cell counts and to measure cytokine release. Lung tissue was used to determine mRNA and protein expression of proinflammatory genes and to assess tissue inflammation. A strong acute inflammatory response characterized by neutrophilic influx, increased cytokine secretion (KC, TNF-α, MIP2, MIP-1α, MCP1), proinflammatory gene expression (KC, MIP2, MMP12), and upregulated GM-CSF production was observed in the mainstream model. After sidestream exposure there was a dampened inflammatory reaction consisting only of macrophages and diminished GM-CSF levels, most likely caused by elevated CO concentrations. These results demonstrate that the composition of CS determines the dynamics of inflammatory cell recruitment in COPD mouse models. Different initial inflammatory processes might contribute to COPD pathogenesis in significantly varying ways, thereby determining the outcome of the studies.
The small airway epithelium (SAE), the first site of smoking-induced lung pathology, exhibits genome-wide changes in gene
expression in response to cigarette smoking. Based on the increasing evidence that the epigenome can respond to external stimuli
in a rapid manner, we assessed the SAE of smokers for genome-wide DNA methylation changes compared with nonsmokers, and whether
changes in SAE DNA methylation were linked to the transcriptional output of these cells. Using genome-wide methylation analysis
of SAE DNA of nonsmokers and smokers, the data identified 204 unique genes differentially methylated in SAE DNA of smokers
compared with nonsmokers, with 67% of the regions with differential methylation occurring within 2 kb of the transcriptional
start site. Among the genes with differential methylation were those related to metabolism, transcription, signal transduction
and transport. For the differentially methylated genes, 35 exhibited a correlation with gene expression, 54% with an inverse
correlation of DNA methylation with gene expression and 46% a direct correlation. These observations provide evidence that
cigarette smoking alters the DNA methylation patterning of the SAE and that, for some genes, these changes are associated
with the smoking-related changes in gene expression.
Addiction to nicotine may result in molecular adaptations in the neurocircuitry of specific brain structures via changes in the cyclic AMP-responsive element binding protein (CREB)-dependent gene transcription program. We therefore investigated the effects of chronic nicotine exposure and its withdrawal on CREB and phosphorylated CREB (p-CREB) protein levels in the rat brain. We report here that chronic nicotine exposure (1-h withdrawal) had no effect on the expression of CREB and p-CREB in the rat cortex and amygdala. On the other hand, decreases in the expression of CREB protein and phosphorylation of CREB occur in the cingulate gyrus, and in the parietal and the piriform but not in the frontal cortex during nicotine withdrawal (18 h) after nicotine exposure. It was also observed that CREB and p-CREB protein levels were significantly decreased in the medial and basolateral, but not in the central amygdala during nicotine withdrawal (18 h) after chronic nicotine exposure . Furthermore, it was found that nicotine withdrawal (18 h) after chronic nicotine exposure leads to decreased CRE-DNA binding without modulating cAMP-dependent protein kinase A activity in the cortex and the amygdala of rats. In addition, chronic nicotine treatment produced anxiolytic effects whereas nicotine withdrawal (18 h) produced anxiety in rats as measured by the elevated plus-maze test. These results provide the first evidence that decreased CREB activity and/or expression in specific cortical and amygdaloid brain structures may be involved in the underlying molecular mechanisms of nicotine dependence.
Environmental factors such as tobacco smoking may have long-lasting effects on DNA methylation patterns, which might lead to changes in gene expression and in a broader context to the development or progression of various diseases. We conducted an epigenome-wide association study (EWAs) comparing current, former and never smokers from 1793 participants of the population-based KORA F4 panel, with replication in 479 participants from the KORA F3 panel, carried out by the 450K BeadChip with genomic DNA obtained from whole blood. We observed wide-spread differences in the degree of site-specific methylation (with p-values ranging from 9.31E-08 to 2.54E-182) as a function of tobacco smoking in each of the 22 autosomes, with the percent of variance explained by smoking ranging from 1.31 to 41.02. Depending on cessation time and pack-years, methylation levels in former smokers were found to be close to the ones seen in never smokers. In addition, methylation-specific protein binding patterns were observed for cg05575921 within AHRR, which had the highest level of detectable changes in DNA methylation associated with tobacco smoking (-24.40% methylation; p = 2.54E-182), suggesting a regulatory role for gene expression. The results of our study confirm the broad effect of tobacco smoking on the human organism, but also show that quitting tobacco smoking presumably allows regaining the DNA methylation state of never smokers.
DNA microarrays have revolutionized environmental research by enabling the discovery of genomic markers that reflect the toxic
effect of various chemicals and by providing information on the underlying mechanisms. Microarray-based toxicogenomics approaches
have become a popular tool to investigate potential risks of exposure to various environmental contaminants at the DNA level.
Especially, the analysis of microarray data that are generated under various experimental conditions is critically important
for validation of biomarkers and, thus, diagnosis and treatment of environmental targets. Presently, we identified commonly
regulated genes whose expression level varied upon exposure to volatile organic compounds (VOCs) by performing cross-experimental
analysis of public gene expression datasets using the RankProd algorithm. VOCs are chemical contaminants that often exhibit
long-term adverse effects upon chronic exposure. Since VOCs are often used in household items and residential buildings, it
is important to understand their effect on human health in a more systematic way. This cross-experiment resulted in a valid
set of commonly regulated genes. The functional analysis of these differentially expressed genes (DEGs) generated several
significantly over-represented Gene Ontology terms and identified metabolic pathways tightly-associated with cancer development.
The functional analysis of identified up-regulated genes (RPL27, RPS6, RPS11, RPS27A, AURKA, FNTA, HSP90AB1) revealed concordance
with genes related to various respiratory symptoms such as non-small cell lung cancer. The selected commonly regulated diseaserelated
genes were also compared with the DEGs identified in previous analysis performed individually for validation of biomarkers.
KeywordsVolatile organic compounds–Cross-experiment–Rankprod algorithm–DNA microarray
Cigarette smoke (CS) exposure is associated with increased mucus production and chronic obstructive pulmonary disease (COPD).
MUC5AC is the major inducible mucus gene in the airway. The purpose of this investigation was to elucidate the mechanisms of CS-induced
activation of MUC5AC gene transcription. We observed that the region −3724/−3224 of the MUC5AC promoter is critical for CS-induced gene transcriptional activity and that this region contains two Sp1 binding sites. Using
a lung-relevant model, we observed that CS increased nuclear Sp1 protein expression. Consequently, CS exposure resulted in
enhanced Sp1-DNA binding activity and Sp1 trans-activation. Co-transfection of the MUC5AC-luc reporter with Sp1 expression
plasmids resulted in significantly increased MUC5AC-luc activity, whereas co-treatment with mithramycin A, a Sp1 inhibitor,
abolished CS-induced MUC5AC promoter activity. Using mobility shift assay and chromatin immunoprecipitation, we demonstrated that two Sp1 binding sites
in the MUC5AC promoter are functional and responsive to CS exposure. A mutation of either Sp1 binding site in the MUC5AC promoter significantly decreased CS-induced promoter activity. Together, these data indicate that CS induces MUC5AC gene transcription predominantly through increased Sp1 nuclear protein levels and increased Sp1 binding to its promoter region.
Innate immune cells of the respiratory tract are the first line of defense against pathogenic and environmental insults. Failure of these cells to perform their immune functions leaves the host susceptible to infection, and may contribute to impaired resolution of inflammation. While combustible tobacco cigarettes have been shown to suppress respiratory immune cell function, the effects of flavored electronic cigarette liquids (e-liquids) and individual flavoring agents on respiratory immune cell responses are unknown. We investigated the effects of seven flavored, nicotine-free e-liquids on primary human alveolar macrophages, neutrophils, and natural killer (NK) cells. Cells were challenged with a range of e-liquid dilutions and assayed for their functional responses to pathogenic stimuli. Endpoints included phagocytic capacity (neutrophils and macrophages), neutrophil extracellular trap formation, proinflammatory cytokine production, and cell mediated cytotoxic response (NK cells). E-liquids were then analyzed via mass spectrometry to identify individual flavoring components. Three cinnamaldehyde-containing e-liquids exhibited dose-dependent, broadly immunosuppressive effects. Quantitative mass spectrometry was used to determine concentrations of cinnamaldehyde in each of the three e-liquids and cells were subsequently challenged with a range of cinnamaldehyde concentrations. Cinnamaldehyde alone recapitulated the impaired function observed with e-liquid exposures and cinnamaldehyde-induced suppression of macrophage phagocytosis was reversed by addition of the small-molecule reducing agent 1,4-dithiothreitol (DTT). We conclude that cinnamaldehyde has the potential to impair respiratory immune cell function, illustrating an immediate need for further toxicological evaluation of chemical flavoring agents to inform regulation governing their use in e-liquid formulations.
E-cigarettes are generally thought of as a safer smoking alternative to traditional cigarettes. However, little is known about the effects of e-cigarette liquids (e-liquids) on the lung. Since over 7,000 unique flavors have been identified for purchase in the USA, our goal was to conduct a screen that would test whether different flavored e-liquids exhibited different toxicant profiles. We tested the effects of 13 different flavored e-liquids (with nicotine and propylene glycol/vegetable glycerin (PG/VG) serving as controls) on a lung epithelial cell line (CALU3). Using the MTT assay as an indicator of cell proliferation/viability, we demonstrated a dose-dependent decrease of MTT metabolism by all flavors tested. However, a group of 4 flavors consistently showed significantly greater toxicity compared to the PG/VG control, indicating the potential for some flavors to elicit more harmful effects than others. We also tested the aerosolized 'vapor' from select e-liquids on cells and found similar dose-dependent trends, suggesting that direct e-liquid exposures are a justifiable first-pass screening approach for determining relative e-liquid toxicity. We then identified individual chemical constituents for all 13 flavors using gas chromatography-mass spectrometry. These data revealed that beyond nicotine and PG/VG, the 13 flavored e-liquids have diverse chemical constituents. Since all of the flavors exhibited some degree of toxicity and a diverse array of chemical constituents with little inhalation toxicity available, we conclude that flavored e-liquids should be extensively tested on a case-by-case basis to determine the potential for toxicity in the lung and elsewhere.
Background:
DNA methylation leaves a long-term signature of smoking exposure and is one potential mechanism by which tobacco exposure predisposes to adverse health outcomes, such as cancers, osteoporosis, lung, and cardiovascular disorders.
Methods and results:
To comprehensively determine the association between cigarette smoking and DNA methylation, we conducted a meta-analysis of genome-wide DNA methylation assessed using the Illumina BeadChip 450K array on 15 907 blood-derived DNA samples from participants in 16 cohorts (including 2433 current, 6518 former, and 6956 never smokers). Comparing current versus never smokers, 2623 cytosine-phosphate-guanine sites (CpGs), annotated to 1405 genes, were statistically significantly differentially methylated at Bonferroni threshold of P<1×10(-7) (18 760 CpGs at false discovery rate <0.05). Genes annotated to these CpGs were enriched for associations with several smoking-related traits in genome-wide studies including pulmonary function, cancers, inflammatory diseases, and heart disease. Comparing former versus never smokers, 185 of the CpGs that differed between current and never smokers were significant P<1×10(-7) (2623 CpGs at false discovery rate <0.05), indicating a pattern of persistent altered methylation, with attenuation, after smoking cessation. Transcriptomic integration identified effects on gene expression at many differentially methylated CpGs.
Conclusions:
Cigarette smoking has a broad impact on genome-wide methylation that, at many loci, persists many years after smoking cessation. Many of the differentially methylated genes were novel genes with respect to biological effects of smoking and might represent therapeutic targets for prevention or treatment of tobacco-related diseases. Methylation at these sites could also serve as sensitive and stable biomarkers of lifetime exposure to tobacco smoke.
There is interest in the relative toxicities of emissions from electronic cigarettes and tobacco cigarettes. Lists of cigarette smoke priority toxicants have been developed to focus regulatory initiatives. However, a comprehensive assessment of e-cigarette chemical emissions including all tobacco smoke Harmful and Potentially Harmful Constituents, and additional toxic species reportedly present in e-cigarette emissions, is lacking. We examined 150 chemical emissions from an e-cigarette (Vype ePen), a reference tobacco cigarette (Ky3R4F), and laboratory air/method blanks. All measurements were conducted by a contract research laboratory using ISO 17025 accredited methods. The data show that it is essential to conduct laboratory air/method measurements when measuring e-cigarette emissions, owing to the combination of low emissions and the associated impact of laboratory background that can lead to false-positive results and overestimates. Of the 150 measurands examined in the e-cigarette aerosol, 104 were not detected and 21 were present due to laboratory background. Of the 25 detected aerosol constituents, 9 were present at levels too low to be quantified and 16 were generated in whole or in part by the e-cigarette. These comprised major e-liquid constituents (nicotine, propylene glycol, and glycerol), recognized impurities in Pharmacopoeia-quality nicotine, and eight thermal decomposition products of propylene glycol or glycerol. By contrast, approximately 100 measurands were detected in mainstream cigarette smoke. Depending on the regulatory list considered and the puffing regime used, the emissions of toxicants identified for regulation were from 82 to >99% lower on a per-puff basis from the e-cigarette compared with those from Ky3R4F. Thus, the aerosol from the e-cigarette is compositionally less complex than cigarette smoke and contains significantly lower levels of toxicants. These data demonstrate that e-cigarettes can be developed that offer the potential for substantially reduced exposure to cigarette toxicants. Further studies are required to establish whether the potential lower consumer exposure to these toxicants will result in tangible public health benefits.
Introduction:
Smoking is the number one modifiable environmental risk factor for chronic obstructive pulmonary disease (COPD). Clinical, epidemiological and increasingly "omics" studies assess or adjust for current smoking status using only self-report, which may be inaccurate. Objective measures such as exhaled carbon monoxide (eCO) may also be problematic owing to limitations in the measurements and the relatively short half life of the molecule. In this study, we determined the impact of different case definitions of current cigarette smoking on gene expression in peripheral blood of patients with COPD.
Methods:
Peripheral blood gene expression from 573 former- and current- smokers with COPD in the ECLIPSE study was used to find genes whose expression was associated with smoking status. Current smoking was defined using self-report, exhaled carbon monoxide (eCO) concentrations, or both. Linear regression was used to determine the association of current smoking status with gene expression adjusting for age, sex and propensity score. Pathway enrichment analyses were performed on genes with P < 0.001.
Result:
Using self-report or eCO, only two genes were differentially expressed between current and ex-smokers, with no enrichment in biological processes. When current smoking was defined using both eCO and self- report, four genes were differentially expressed (LRRN3, PID1, FUCA1, GPR15) with enrichment in 40 biological pathways related to metabolic processes, response to hypoxia and hormonal stimulus. Additionally, the combined definition provided better distributions of test statistics.
Conclusion:
A combined phenotype of eCO and self report allows for better discovery of genes and pathways related to current smoking.
Implications:
Studies relying only on self report of smoking status to assess or adjust for the impact of smoking may not fully capture its effect and will lead to residual confounding of results.
The relationship between smoking and respiratory disease has long been established and smoking is recognised as a risk factor for chronic obstructive pulmonary disease (COPD) (Fletcher and Peto, 1977), lung cancer (Doll et al, 2004) and interstitial lung diseases (Bradley et al, 2008), as well as contributing to the symptoms of asthma (Siroux et al, 2000). However, when working with patients who have lived with their disease for some time, or who may feel it is too late to benefit from change, it is important to do more than simply reiterate the risks. The link between continued smoking, progression of respiratory disease, exacerbation of the condition and the detrimental effects of continued smoking on the efficacy of some treatments should also be communicated. This article looks at the risks of smoking, as well as providing guidance for community nurses on how to bring up the topic with their patients in a non-confrontational manner.
DNA double-strand breaks (DSBs) are cytotoxic lesions that threaten genomic integrity. Failure to repair a DSB has deleterious consequences, including genomic instability and cell death. Indeed, misrepair of DSBs can lead to inappropriate end-joining events, which commonly underlie oncogenic transformation due to chromosomal translocations. Typically, cells employ two main mechanisms to repair DSBs: homologous recombination (HR) and classical nonhomologous end joining (C-NHEJ). In addition, alternative error-prone DSB repair pathways, namely alternative end joining (alt-EJ) and single-strand annealing (SSA), have been recently shown to operate in many different conditions and to contribute to genome rearrangements and oncogenic transformation. Here, we review the mechanisms regulating DSB repair pathway choice, together with the potential interconnections between HR and the annealing-dependent error-prone DSB repair pathways.
Cigarette smoking is a major environmental contributor to chronic obstructive pulmonary disease (COPD), but its epigenetic regulation of oxidative genes involved in the pathogenesis of COPD remains elusive.
We analyzed DNA methylation on GCLC, GSTM1, GSTP1, and SOD3 promoters in clinical samples from COPD patients (current-smokers: CS-COPD; ex-smokers: ES-COPD) and subjects with normal pulmonary function (current-smokers: CS-NS; ex-smokers: ES-NS; never-smokers: NC). Expression of GCLC mRNA and GSH synthesis in these clinical samples and human bronchial epithelial BEAS-2B cells stimulated by cigarette smoke extract (CSE) was evaluated. GCLC mRNA and protein levels were measured to determine effects of demethylation and deacetylation agents on CSE-treated BEAS-2B cells.
The DNA methylation level of the GCLC promoter was significantly increased in CS-COPD, CS-NS, and ES-COPD compared to ES-NS and NC. However, there were no significant differences of DNA methylation values in GSTM1, GSTP1, and SOD3 promoters among these groups. Expression of GCLC mRNA was downregulated in the lungs and GSH levels decreased in plasma as a consequence of hypermethylation of the GCLC promoter. Similarly, CSE-treated BEAS-2B cells had hypermethylation of the GCLC gene, mRNA downregulation, and a decreased intracellular GSH level. GCLC expression in CSE-treated BEAS-2B cells was restored by the methylation inhibitor, 5-Aza, but not by the deacetylation agent, TSA.
Cigarette smoke-induced hypermethylation of the GCLC promoter is related to the initiation and progression of COPD. Our finding may provide a new strategy for the intervention of COPD by developing demethylation agents targeting GCLC hypermethylation.
Volatile organic compounds (VOCs) can be easily taken up by humans, leading to various diseases, such as respiratory system and central nervous system disorders. Environmental risk assessment is generally conducted using traditional tests, which may be time-consuming and technically challenging. Therefore, analysis of the effects of VOCs, such as toluene, ethylbenzene, and xylene, may be improved by use of novel, high-throughput methods, such as microarray analysis. In this study, we examined the effects of VOCs exposure in humans on gene expression and methylation using microarray analysis. We recruited participants who had short-term exposure, long-term exposure, or no exposure. We then analyzed changes in gene expression in blood samples from these participants. A total of 866 genes were upregulated, while 366 genes were downregulated in the short-term exposure group. Similarly, in the long-term exposure group, a total of 852 and 480 genes were up- or downregulated, respectively. Hierarchical clustering analysis was used to divide the clustered genes into nine clusters to investigate the expression of variations in accordance with the exposure period. And the methylation microarray was performed at the same time to see whether this expression variation is related to the epigenetic study. Finally, we have 5 genes that were upregulated and 12 genes that were downregulated, gradually and respectively, so these genes are expected to function as biomarkers of the duration of exposure to VOCs. Further research is required to determine the time-dependent effects of VOCs on epigenetic regulation of gene expression. © 2015 Wiley Periodicals, Inc. Environ Toxicol, 2015.
© 2015 Wiley Periodicals, Inc.
Tobacco use is associated with heart and respiratory diseases and also with a number of types of cancer. Tobacco smoke contains more than 6000 chemicals and of the most abundant ones are the aldehydes. Aldehydes have been previously shown in in vitro studies to induce intracellular oxidative stress and activation of stress signaling pathways, which are associated with cardiovascular disease such as atherosclerosis. Also, aldehydes form one of the toxicant groups recommended for future tobacco product regulation due to its harmful effect. However, the in vitro effect of low levels aldehyde exposure has not been established. In this study, we determined the gene expression effects of aldehydes commonly found in tobacco smoke by exposing in vitro human umbilical vein epithelial cells (HUVEC). The most relevant aldehydes are used: formaldehyde, acetaldehyde, acrolein, propionaldehyde, crotonaldehyde and butyraldehyde. Sub-cytotoxic exposure levels of the different aldehydes were tested regarding cell proliferation, gene expression changes, oxidative stress responses, and DNA damage. Genes associated with cardiovascular disease development such as DEPP, ARID5B, DKK1, EGR1 and IER3 were found to be dysregulated. Gene expression responses were not related to measurements of oxidative stress or DNA damage using comet assay. These findings suggest that the exposure of low-level aldehydes from tobacco smoke needs to be controlled due to its effect on genes associated with cardiovascular disease.
Aromatic amines (AAs) are an important class of chemicals which account for 12 % of known carcinogens. The biological effects of AAs depend mainly on their biotransformation into reactive metabolites or into N-acetylated metabolites which are generally considered as less toxic. Although the activation of the aryl hydrocarbon receptor (AhR) pathway by certain carcinogenic AAs has been reported, the effects of their N-acetylated metabolites on the AhR have not been addressed. Here, we investigated whether carcinogenic AAs and their N-acetylated metabolites may activate/modulate the AhR pathway in the absence and/or the presence of a bona fide AhR ligand (benzo[a]pyrene/B(a)P]. In agreement with previous studies, we found that certain AAs activated the AhR in human liver and lung cells as assessed by an increase in cytochrome P450 1A1 (CYP1A1) expression and activity. Altogether, we report for the first time that these properties can be modulated by the N-acetylation status of the AA. Whereas 2-naphthylamine significantly activated the AhR and induced CYP1A1 expression, its N-acetylated metabolite was less efficient. In contrast, the N-acetylated metabolite of 2-aminofluorene was able to significantly activate AhR, whereas the parent AA, 2-aminofluorene, did not. In the presence of B(a)P, activation of AhR or antagonist effects were observed depending on the AA or its N-acetylated metabolite. Activation and/or modulation of the AhR pathway by AAs and their N-acetylated metabolites may represent a novel mechanism contributing to the toxicological effects of AAs. More broadly, our data suggest biological interactions between AAs and other classes of xenobiotics through the AhR pathway.
Objective:
Maternal cigarette smoking is paradoxically associated with a decreased risk of developing preeclampsia. Since preeclampsia is thought to be associated with altered mechanisms of angiogenesis and oxidative stress, we aim to investigate the influence of maternal smoking on the early placental expression of a panel of genes related to angiogenesis and oxidative stress.
Material and methods:
We collected villous tissue samples at 6-7 and 10-11 weeks of gestation from 31 women requesting surgical termination. Placental expression of the following genes were quantified by real-time PCR: vascular endothelial growth factor A (VEGFA), fms-like tyrosine kinase (Flt-1), soluble endoglin (sEng), placental growth factor (PlGF), heme oxygenase-1 (HMOX-1) and superoxide dismutase (SOD). Maternal smoking status was assessed by levels of serum cotinine.
Results:
Placental expression of VEGFA was significantly higher in smoking women at 10-11 weeks of gestation compared with nonsmoking women at the same gestational age. There was no significant difference at 6-7 weeks of gestation. There was no variation in the expression of the other genes explored related to smoking status.
Conclusions:
Here we report that VEGFA placental expression was higher in smoking women at 10-11 weeks of gestation. Increased VEGFA expression in the early stages of pregnancy in smoking women might contribute to the decreased risk of developing preeclampsia.
Cigarette smoke (CS)-mediated oxidative stress induces several signaling cascades, including kinases, which results in chromatin modifications (histone acetylation/deacetylation and histone methylation/demethylation). We have previously reported that CS induces chromatin remodeling in pro-inflammatory gene promoters; however, the underlying site-specific histone marks formed in histones H3 and H4 during CS exposure in lungs in vivo and in lung cells in vitro, which can either drive gene expression or repression are not known. We hypothesize that CS exposure in mouse and human bronchial epithelial cells (H292) can cause site-specific posttranslational histone modifications (PTMs) that may play an important role in the pathogenesis of CS-induced chronic lung diseases. We used a bottom-up mass spectrometry approach to identify some potentially novel histone marks, including acetylation, mono-methylation and di-methylation in specific lysine and arginine residues of histones H3 and H4 in mouse lungs and H292 cells. We found that CS-induced distinct posttranslational histone modification patterns in histone H3 and histone H4 in lung cells, which may be considered as usable biomarkers for CS-induced chronic lung diseases. These identified histone marks (histone H3 and histone H4) may play an important role in epigenetic state during the pathogenesis of smoking-induced chronic lung diseases, such as chronic obstructive pulmonary disease and lung cancer.
Most biomarkers of exposure tend to have short half-lives. This includes cotinine, a metabolite of nicotine widely used to assess smoke exposure. Cotinine is thus unsuitable as a determinant of past exposure to cigarette smoke.
We used bisulphite pyrosequencing of a set of four genomic loci (AHRR, 6p21, and two at 2q37) that had differential DNA methylation levels in peripheral blood DNA dependent on tobacco exposure to create a predictive model of smoking status.
Combining four gene loci into a single methylation index provided high positive predictive and sensitivity values for predicting former smoking status in both test (n = 81) and validation (n = 180) sample sets.
This study provides a direct molecular measure of prior exposure to tobacco that can be performed using the quantitative approach of bisulphite pyrosequencing. Epigenetic changes that are detectable in blood may more generally act as molecular biomarkers for other exposures that are also difficult to quantify in epidemiological studies.
The protein chaperone heat shock protein 90 (Hsp90) is a major regulator of different transcription factors such as MyoD, a basic helix loop helix (bHLH) protein, and the bHLH-Per-aryl hydrocarbon nuclear translocator (ARNT)-Sim (PAS) factors Sim and aryl hydrocarbon receptor (Ahr). The transcription factor hypoxia-inducible factor-1α (HIF-1α), involved in the response to hypoxia, also belongs to the bHLH-PAS family. This work was aimed to investigate the putative role of Hsp90 in HIF-1 activation by hypoxia. Using a EGFP-HIF-1α fusion protein, co-immunoprecipitation experiments evidenced that the chimeric protein expressed in COS-7 cells interacts with Hsp90 in normoxia but not in hypoxia. We also demonstrated that Hsp90 interacts with the bHLH-PAS domain of HIF-1α. Moreover, Hsp90 is not co-translocated with HIF-1α into the nucleus. At last, we showed that Hsp90 activity is essential for HIF-1 activation in hypoxia since it is inhibited in the presence of geldanamycin. These results indicate that Hsp90 is a major regulator in HIF-1α activation.
INTRODUCTION Cigarette smoke is a complex mixture of chemicals. Some smoke components, such as carbon monoxide (CO), hydrogen cyanide (HCN), and nitrogen oxides, are gases. Others, such as formaldehyde, acrolein, benzene, and certain N-nitrosamines, are volatile chemicals contained in the liquid- vapor portion of the smoke aerosol. Still others, such as nicotine, phenol, polyaromatic hydrocarbons (PAHs), and certain tobacco-specific nitrosamines (TSNAs), are contained in the submicron-sized solid particles that are suspended in cigarette smoke.
Tobacco smoke consists of thousands of harmful components. A major class of chemicals found in tobacco smoke is formed by aldehydes, in particular formaldehyde, acetaldehyde and acrolein. The present study investigates the gene expression changes in human lung alveolar epithelial cells upon exposure to formaldehyde, acrolein and acetaldehyde at sub-cytotoxic levels. We exposed A549 cells in vitro to aldehydes and non-aldehyde chemicals (nicotine, hydroquinone and 2,5-dimethylfuran) present in tobacco smoke and used microarrays to obtain a global view of the transcriptomic responses. We compared responses of the individual aldehydes with that of the non-aldehydes. We also studied the response of the aldehydes when present in a mixture at relative concentrations as present in cigarette smoke. Formaldehyde gave the strongest response; a total of 66 genes were more than 1.5-fold differentially expressed mostly involved in apoptosis and DNA damage related processes, followed by acetaldehyde (57 genes), hydroquinone (55 genes) and nicotine (8 genes). For acrolein and the mixture only one gene was upregulated involved in oxidative stress. No gene expression effect was found for exposure to 2,5-dimethylfuran. Overall, aldehyde responses are primarily indicative for genotoxicity and oxidative stress. These two toxicity mechanisms are linked to respiratory diseases such as cancer and COPD, respectively. The present findings could be important in providing further understanding of the role of aldehydes emitted from cigarette smoke in the onset of pulmonary diseases.
Cigarette smoking is the major risk factor for smoking-related interstitial fibrosis (SRIF). Despite recent advances, the molecular mechanisms involved in the initiation and progression of this disease remain elusive. We found 6 months of chronic mainstream smoking exposure induced SRIF in C57 mice, which was associated with pronounced enhanced oxidative stress, bronchoalveolar inflammation and fibrosis but not apoptosis of alveolar septal cell. We used Affymetrix microRNA (miRNA) arrays to determine the temporal alteration in global gene expression of peripheral blood during the progression of diffuse pulmonary interstitial fibrosis in C57 mice. Microarray analysis revealed the upregulation of 3 miRNAs (miR-92b, miR-700 and miR-668) and the downregulation of 5 miRNAs (let-7e, miR-142-5p, miR-350, miR-19a and miR191*) in the peripheral blood of mice exposed to mainstream smoking for 1, 2, 3 and 6 months. We proposed that circulating miRNAs might be promising biomarkers to reflect the dynamic pathological changes of SRIF related interstitial fibrosis.