Prenatal environmental tobacco smoke exposure increases allergic asthma risk with methylation changes in mice

Allergic asthma remains an inadequately understood disease. In utero exposure to environmental tobacco smoke (ETS) has been identified as an environmental exposure that can increase an individual's asthma risk. To improve our understanding of asthma onset and development, we examined the effect of in utero ETS exposure on allergic disease susceptibility in an asthmatic phenotype using a house dust mite (HDM) allergen‐induced murine model. Pregnant C57BL/6 mice were exposed to either filtered air or ETS during gestation, and their offspring were further exposed to HDM at 6–7 weeks old to induce allergic inflammation. Methylation in the promoter regions of allergic inflammation‐related genes and genomic DNA was quantified. Exposure to HDM resulted in the onset of allergic lung inflammation, with an increased presence of inflammatory cells, Th2 cytokines (IL‐4, IL‐5, and IL‐13), and airway remodeling. These asthmatic phenotypes were significantly enhanced when the mice had been exposed to in utero ETS. Furthermore, prenatal ETS exposure and subsequent HDM (ETS/HDM)‐induced asthmatic phenotypes agree with methylation changes in the selected asthma‐related genes, including IL‐4, IL‐5, IL‐13, INF‐γ, and FOXP3. Global DNA methylation was significantly lower in ETS/HDM‐exposed mice than that of controls, which coincides with the results observed in lung, spleen, and blood DNAs. Prenatal ETS exposure resulted in a severe increase in allergic inflammatory responses after an HDM challenge, with corresponding methylation changes. Prenatal ETS exposure may influence developmental plasticity and result in altered epigenetic programming, leading to an increased susceptibility to asthma. Environ. Mol. Mutagen. 58:423–433, 2017. © 2017 Wiley Periodicals, Inc.     

Challenge with environmental tobacco smoke exacerbates allergic airway disease in human beings

BACKGROUND: Despite widespread perceptions that environmental tobacco smoke (ETS) is a potent risk factor for allergic airway disease, epidemiologic studies studying this have been equivocal. There is a clear need for experimental studies to address these questions. OBJECTIVE: We directly tested the hypothesis that ETS could interact with allergen in human beings to alter immune responses and promote changes associated with allergic airway disease. METHODS: In a randomized, placebo-controlled crossover study, 19 nonsmoking volunteers with ragweed allergy underwent nasal lavage followed by controlled chamber exposures to 2 hours ETS or clean air followed by another nasal lavage. Subjects immediately randomly received nasal challenge with either ragweed allergen or placebo (300 microL saline). Lavages were also performed 10 minutes, 24 hours, and 4 and 7 days after challenge and IgE, cytokines, and histamine measured. The other arms of the study were spaced at least 6 weeks apart. RESULTS: Environmental tobacco smoke promoted the production of allergen-specific IgE, the hallmark of allergic disease in nasal lavage fluid. Four days after exposure to ETS/ragweed, levels were on average 16.6-fold higher than after clean air/ragweed challenge. In addition, ETS (vs air) promoted the induction of a T(H)2-cytokine nasal milieu (increased IL-4, IL-5, and IL-13 and decreased IFN-gamma production), characteristic of an active allergic response. Moreover, nasal histamine levels were 3.3-fold greater after ETS/ragweed challenge than after clean air/ragweed challenge. CONCLUSION: These studies provide the first experimental evidence that secondhand smoke can exacerbate allergic responses in human beings. CLINICAL IMPLICATIONS: The studies suggest that patients with allergies should avoid tobacco smoke.     

Uptake of tobacco smoke constituents on exposure to environmental tobacco smoke (ETS)

Summary For the purpose of risk evaluation, passive smoking is frequently regarded as low-dose cigarette smoking. However, since the physical, chemical and biological properties of mainstream smoke (MS), which is inhaled by the smoker and environmental tobacco smoke (ETS), which is breathed by the passive smoker are quite different, risk extrapolation from active smoking to passive smoking is of doubtful value. In a series of experimental exposure studies we compared the uptake of tobacco smoke constituents by active and passive smoking. The results show that biomarkers which were found to be elevated after experimental ETS exposure, such as nicotine and cotinine in plasma and urine as well as thioethers in urine, indicate gas-phase exposure in passive smokers, but particle-phase exposure in active smokers. Biomarkers which should indicate the uptake of particle-bound, genotoxic substances with ETS, such as urinary mutagenicity, metabolites of polycyclic aromatic hydrocarbons (PAH) and DNA adducts, were not found to be elevated even after extremely high ETS exposure. From these results we conclude that a risk evaluation for passive smoking on the basis of dosimetric data is currently not possible.Abbreviations 1-ABP 4-aminobiphenyl - BaA benzo(a)anth-racene - BaP benzo(e)pyrene - BE butanol extraction - BeP benzo(e)pyrene - CO carbon monoxide - COHb carboxyhae-moglobin - DABS DNA binding substances - DRZ diagonal radioactive zone - ETS environmental tobacco smoke - GC gas chromatography - GC/MS gas chromatography coupled to mass spectrometry - HPLC high performance liquid chromatography - HPMA 3-hydroxypropylmercapturic acid - MS mainstream smoke - NNK 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone - NNN N-nitrosonornicotine - NO_xa nitrogen oxides (NO/NO₂) - PAH polycyclic aromatic hydrocarbons - PhIP 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine - P1 nuclease P1 - RSP respirable particles     

Progesterone and environmental tobacco smoke act synergistically to exacerbate the development of allergic asthma in a mouse model

BACKGROUND: Asthma affects males and females differently. Females have a higher incidence than males after the onset of puberty. This suggests a hormonal component to the development of the disease. Progesterone, a female hormone, has previously been shown to illicit a T-helper type 2 (TH2) immune response similar to that seen in allergic asthma. Previous studies performed by our laboratory have shown that exposure to environmental tobacco smoke (ETS) enhances the immune response to allergens. OBJECTIVE: To determine if the combination of exposure to ETS and progesterone would further exacerbate the immune response in a mouse model of allergic asthma. METHODS: Female mice were ovariectomized and then implanted with time-release progesterone pellets. Mice were housed in either filtered air (FA) or ETS chambers and half were exposed to aerosolized house dust mite allergen (HDMA). Bronchoalveolar lavage was performed for cell differentials; lung and spleen cells were harvested to compare IL-4 and IFN-gamma production by ELISPOT. RESULTS: Progesterone pellet implantation resulted in increased serum progesterone levels (28.3+/-8.43 vs. 13.5+/-7.22 ng/mL in placebo-treated mice, P<0.0001). Serum total IgE levels were significantly greater in progesterone vs. non-progesterone treated animals that were also exposed to HDMA. ETS exposure enhanced total IgE levels as well. Lung homogenate cells from HDMA/progesterone-treated animals stimulated with Concavalin A produced significantly more IL-4 compared with HDMA/placebo-treated animals (200+/-17.6 vs. 146+/-17.5 spots/well, P<0.01 in ETS exposed animals and 221+/-28.9 vs. 167+/-23.4 spots/well, P<0.01 in animals housed in FA). HDMA/ETS-treated animals had higher eosinophilia in lavage than all other groups. CONCLUSION: Increased serum progesterone levels exacerbate the allergic asthmatic phenotype in a mouse model. These effects are further exacerbated by the addition of environmental tobacco smoke. Progesterone provides a major contribution to the gender differences seen in the development and elicitation of the asthmatic response.     

Increased IgE antibody responses in rats exposed to tobacco smoke

Raised serum IgE levels were found in a high proportion of rats that had been exposed to tobacco smoke twice daily 5 days a week for 8 wk in a Dontenville-type smoking machine. Levels above 1 ng/ml of IgE were found in nine of 20 animals exposed to cigarette smoke and in five of 20 rats exposed to smoke from cigarettes with 1.45% phenylmethyloxidiazole added for possible protection against the effects of the smoke. None of the 20 control rats exhibited similarly increased serum IgE. Exposure to tobacco smoke did not significantly affect the serum concentrations of IgM and IgG. The development of specific IgE and IgG antibodies was also influenced by tobacco smoke exposure. Rats exposed to ovalbumin aerosol developed increased levels of IgG and IgE antibodies, whereas no effect on the development of antibody titers was found in rats immunized by the subcutaneous route. This study demonstrates that exposure to tobacco smoke increases serum IgE levels and enhances sensitization via the airways by a local effect, thus supporting the "mucosal theory of atopy."     

The behavioral response to novelty is altered in rats neonatally exposed to cocaine

It has recently been suggested that the effects of in utero cocaine exposure may result in subtle deficits related to a challenging environment, including exposure to novelty or stress. This study used a neonatal drug-exposure model to examine the behavioral response to a novel environment in rodents. Subjects were artificially reared (AR) from postnatal Days 4-10. There were four treatment groups; AR 40 mg/kg/day cocaine, AR 20 mg/kg/day cocaine, AR control group receiving no drug, and a normally reared control. In Experiment 1, subjects were tested for their preference of maternal home-cage or clean wood-chip odors in a T-maze on postnatal Day 15. Subjects from all treatment groups preferred the maternal odor. In Experiment 2, subjects were habituated to four familiar odors and tested with a novel odor in an open field (postnatal Days 16-21). Neonatal exposure to 20 mg/kg/day cocaine led to an overall increase in exploratory behavior during testing, whereas 40 mg/kg/day did not, supporting the hypothesis that developmental exposure to cocaine at some doses may alter the offspring's response to a changing environment.     

The role of environmental tobacco smoke in genetic susceptibility to asthma

PURPOSE OF REVIEW: The increase in asthma prevalence over the past 50 years suggests that exposures to environmental risk factors have also increased during this time. Environmental tobacco smoke is one of the most common indoor air pollutants and has been associated in epidemiologic studies with airway and allergic phenotypes in exposed individuals. However, symptoms occur in only some individuals, suggesting that individual genotypes determine sensitivity to environmental tobacco smoke exposure. In this review, we summarize studies evaluating the relationship between genotype, environmental tobacco smoke exposure and risk for asthma and related phenotypes. RECENT FINDINGS: Using either candidate gene or genome-wide approaches, a number of studies have examined interactions between genotypes at specific loci or genome regions and environmental tobacco smoke exposure and risk for asthma or asthma-associated phenotypes. These studies implicate variation in the genes encoding the alpha(2)-adrenergic receptor, interleukin-10, glutathione S-transferase M1, interleukin-1 beta and interleukin-1 receptor antagonist, matrix metalloproteinases 1 and 12, interleukin-4 receptor alpha-chain, alpha(1)-antitrypsin, and microsomal epoxide hydrolase, as well as unknown genes on chromosomes 1p, 5q and 17p as contributing toward susceptibility in smoking exposed individuals. SUMMARY: Considering environmental tobacco smoke exposure in genetic studies may help to identify more homogeneous subsets of patients that share a common disease etiology. By stratifying samples by environmental tobacco smoke exposure, associations or linkages with specific polymorphisms or chromosomal region may be revealed, as illustrated in the studies discussed in this review.     

Determination of DNA single-strand breaks in lymphocytes of smokers and nonsmokers exposed to environmental tobacco smoke using the nick translation assay

The detection of DNA single-strand breaks (SSB) in human mononucleated white blood cells (MWBC) using a modified version of the nick translation assay is presented. This assay allows rapid and sensitive examination of SSB using only 5 ml heparinized blood for an eightfold determination. The assay was standardized by incubation of MBWC in vitro with N-methyl-N-nitro-N-nitro-soguanidine (MNNG), a known genotoxic agent. In vitro incubation of MWBC with MNNG induced a dose-dependent increase in DNA-SSB at doses between 5 and 500 M MNNG. The detection limit for the assay was 5 M MNNG. To assess the suitability of this assay to detect SSB in vivo a controlled study was performed in which volunteer smokers (n = 5), nonsmokers (n = 5) exposed to environmental tobacco smoke (ETS), and nonsmoker controls (n = 5) were compared. The study lasted 4 experimental days, 2 control and 2 exposure days. On control days (days 1 and 3) smokers and nonsmokers sat in an unventilated 45 m³ room for 8 h. On the exposure days (days 2 and 4) each of the five smokers smoked 24 cigarettes in 8 h, while the five nonsmokers were exposed to the ETS generated by the smoking volunteers. High exposure to tobacco smoke was confirmed by dosimetry of carboxyhemoglobin (COHb), plasma nicotine and cotinine levels. Blood was drawn before and after each exposure on all 4 experimental days for determination of DNA-SSB in lymphocytes immediately after isolation of blood cells. COHb, plasma nicotine, and cotinine levels were considerably increased in both smokers and nonsmokers exposed to ETS on days 2 and 4. DNA-SSB were detected in all volunteers with intra-and interindividual day to day and morning to evening variations. After smoking, SSB increased on day 2 and on day 4 in smokers. In nonsmokers exposed to ETS no exposure-related variation in SSB levels was found. We conclude that the modified nick translation assay is sensitive enough to detect SSB induced in vivo by exposure to a genotoxic agent and could therefore be used in biological monitoring at the workplace.Abbreviations COHb carboxyhemoglobin - DMEM Dulbecco's modification of Eagle's minimal essential medium - SSB single-strand break - ETS environmental tobacco smoke - MNNG N-methyl-N-nitro-N-nitrosoguanidine - MWBC mononucleated white blood cells - NT nick translation     

Exposure of children with cystic fibrosis to environmental tobacco smoke

BACKGROUND. In children, passive exposure to environmental tobacco smoke has been associated with growth suppression and an increased frequency of respiratory tract infections. On the assumption that this association would be more pronounced in children with chronic pulmonary disease, we examined the growth, nutritional status, lung function, and clinical condition of children with cystic fibrosis in relation to their exposure to environmental tobacco smoke. METHODS. We studied 43 children (age, 6 to 11 years) on entry to a summer camp and then again after two weeks in this smoke-free environment. Twenty-four of the children (56 percent) came from homes with smokers. RESULTS. There appeared to be a dose-dependent relation between the estimate of smoke exposure (cigarettes smoked per day in the home) and overall severity of disease, as assessed by the age-adjusted rate of hospital admissions (r = 0.58), peak expiratory flow rate (r = -0.39), and measures of growth and nutrition, including weight percentile (r = -0.37), height percentile (r = -0.44), midarm circumference (r = -0.42), and triceps skin-fold thickness (r = -0.31). These effects were most evident in the girls. When only the 24 children from homes with smokers were analyzed, however, the dose-dependent relation was present only for the number of hospital admissions and for height. Among the children with good lung function (n = 21) or with normal weight for height (n = 27) at the start of camp, those who had been exposed to tobacco smoke gained significantly more weight during the two weeks of camp than did the children from smoke-free homes. CONCLUSIONS. These data suggest that passive exposure to tobacco smoke adversely affects the growth and health of children with cystic fibrosis, although the possibility cannot be ruled out that social, economic, or other factors determined both the smoking status of the household and the nutritional status of the children.     

Impaired lung homeostasis in neonatal mice exposed to cigarette smoke

In infants, smoke exposure is associated with more respiratory illnesses and decreased lung function. We hypothesized that perinatal lung is particularly susceptible to the damaging effects of cigarette smoke (CS) and that exposure to CS during this period may alter expression of immune response genes and adversely affect lung growth. To test this, we exposed neonatal mice to 14 days of CS. Immediately after exposure to CS, pulmonary gene expression profiling was performed on 2-week-old CS-exposed lung and age-matched control lung. Nitrotyrosine, TUNEL, MAC3, and phospho-SMAD-2 (p-SMAD2) staining was also performed. At 8 weeks of age, lung volume measurements were determined and mean linear intercept measurements were calculated. Pulmonary gene expression profiling revealed that CS exposure significantly inhibited type 1 and type 2 interferon pathway genes in neonatal lung, compared with age-matched control lung. Neonatal CS-exposed lung also had a significant increase in n-tyrosine, TUNEL, and p-SMAD2 staining when compared with adult CS-exposed lung and age-matched control lung. Lung volumes at 8 weeks of age were modestly but significantly decreased in mice exposed to CS in the neonatal period compared with age-matched controls, consistent with impaired lung growth. The results of this study indicate that exposure to CS during the neonatal period inhibits expression of genes involved in innate immunity and mildly impairs postnatal lung growth. These findings may in part explain the increased incidence of respiratory symptoms in infants and children exposed to CS.     

Gender differences in autoimmunity associated with exposure to environmental factors

Autoimmunity is thought to result from a combination of genetics, environmental triggers, and stochastic events. Gender is also a significant risk factor with many diseases exhibiting a female bias. Although the role of environmental triggers, especially medications, in eliciting autoimmunity is well established less is known about the interplay between gender, the environment and autoimmunity. This review examines the contribution of gender in autoimmunity induced by selected chemical, physical and biological agents in humans and animal models. Epidemiological studies reveal that environmental factors can be associated with a gender bias in human autoimmunity. However many studies show that the increased risk of autoimmunity is often influenced by occupational exposure or other gender biased activities. Animal studies, although often prejudiced by the exclusive use of female animals, reveal that gender bias can be strain specific suggesting an interaction between sex chromosome complement and background genes. This observation has important implications because it argues that within a gender biased disease there may be individuals in which gender does not contribute to autoimmunity. Exposure to environmental factors, which encompasses everything around us, adds an additional layer of complexity. Understanding how the environment influences the relationship between sex chromosome complement and innate and adaptive immune responses will be essential in determining the role of gender in environmentally-induced autoimmunity.     

Mutation spectrum in Salmonella induced by environmental tobacco smoke.

Environmental tobacco smoke (ETS) is a major source of indoor air pollution. Extractable-respirable particulate (ERP) from the ETS-contaminated indoor air (ERP-ETS) was collected from six passenger train cars and one control room. The mutagenicity of ERP-ETS was tested in the Ames/Salmonella test in the presence of male rat liver microsomal fraction S9. The mutation spectrum of ERP-ETS was determined by colony probe hybridization and polymerase chain reaction/DNA sequence analysis in approximately 2,370 His+ revertants. The results indicate that the majority of ERP-ETS-induced mutations were a two-base deletion of GC or CG within the hotspot sequence of CGCGCGCG at the frameshift hisD3052 allele in strain TA98. The ERP-ETS from the control room induced approximately 94.3% such deletions, while the ERP-ETS collected from the passenger cars induced approximately 89.6% such deletions. The ERP-ETS either from the control room or from the passenger cars induced approximately 74% C/G --> A/T transversions, and approximately 23% C/G --> T/A transitions within the primary target CCC at the hisG46 allele in strain TA100.     

Mould extracts increase the allergic response to ovalbumin in mice

BACKGROUND: Exposure to moulds in indoor air is thought to induce asthma in susceptible persons. Moulds may contain several potent allergens. However, more importantly, moulds may increase the allergic response to other allergens (adjuvant effect). Previously, we have found that a beta-1,3-glucan from the cell wall of the fungus Sclerotinia sclerotiorum increases the allergic response to the model allergen ovalbumin (OVA) in a mouse model. OBJECTIVE: In the present study, we wanted to confirm the adjuvant effect of another beta-1,3-glucan, MacroGard (MG) from baker's yeast in this model. More importantly, we wished to explore the putative effects of extracts from the moulds Cladosporium herbarum (CH) and Penicillium chrysogenum (PC) using the very same model as used to explore effects of beta-glucans. METHODS: Groups of eight Balb/c mice were injected with OVA alone, OVA+extract or OVA+MG, into one footpad. On day 21, all mice were reinjected with OVA, before exsanguination on day 26. The levels of OVA-specific IgE, IgG1 and IgG2a in serum were measured by ELISA. RESULTS: Compared with OVA alone, OVA+MG, OVA+CH extract and OVA+PC extract increased OVA-specific IgE and IgG1 levels significantly. For all groups, the levels of IgG2a anti-OVA remained similar to those of the OVA-alone group. CONCLUSIONS: Our results show that extracts from CH and PC, and the beta-1,3/1,6-glucan from baker's yeast have adjuvant effects on the allergic response in mice.