Ozone, oxidant defense genes, and risk of asthma during adolescence

Web-based tools for modelling and analysis of multivariate data: California ozone pollution activity

This article presents a hands-on web-based activity motivated by the relation between human health and ozone pollution in California. This case study is based on multivariate data collected monthly at 20 locations in California between 1980 and 2006. Several strategies and tools for data interrogation and exploratory data analysis, model fitting and statistical inference on these data are presented. All components of this case study (data, tools, activity) are freely available online at: http://wiki.stat.ucla.edu/socr/index.php/SOCR_MotionCharts_CAOzoneData. Several types of exploratory (motion charts, box-and-whisker plots, spider charts) and quantitative (inference, regression, analysis of variance (ANOVA)) data analyses tools are demonstrated. Two specific human health related questions (temporal and geographic effects of ozone pollution) are discussed as motivational challenges.

The association between adult asthma and superoxide dismutase and catalase gene activity

BACKGROUND

Adult asthma is caused by interaction effects of multiple genetic and environmental factors. Some studies have suggested that antioxidant enzyme activity and gene polymorphisms may play important roles in the context of asthma. Therefore, our study objectives were to investigate the association between asthma, antioxidant activities and the polymorphisms of manganese superoxide dismutase (Mn-SOD) or catalase (CAT).

MATERIALS AND METHODS

A case-control study, for which we recruited 250 asthmatic adults and 250 age- and sex-matched controls. All subjects completed a questionnaire. Waist and hip circumference measurements, a lung function test and DNA genotyping were performed. In total, 50 incident cases and 50 matched controls who were non-smokers or had quit smoking for at least 1 year were selected in order to investigate SOD and CAT activity levels.

RESULTS

In our study, we did not find a significant association between Mn-SOD Ala16Val, CAT C-262T and asthma. The level of SOD activity in new-onset asthma patients was significantly lower than in control subjects (p < 0.0005). The level of CAT activity in new-onset asthma patients was significantly higher than in control subjects (p < 0.0005).

CONCLUSIONS

The levels of SOD and CAT activity were significantly related to adult asthma. SOD and CAT activity may be good tools to differentiate potential asthma sufferers. This would enable us to further investigate the mechanism of defective antioxidant enzymes in the context of asthma pathogenesis.

Antioxidant components of naturally-occurring oils exhibit marked anti-inflammatory activity in epithelial cells of the human upper respiratory system

BACKGROUND

The upper respiratory tract functions to protect lower respiratory structures from chemical and biological agents in inspired air. Cellular oxidative stress leading to acute and chronic inflammation contributes to the resultant pathology in many of these exposures and is typical of allergic disease, chronic sinusitis, pollutant exposure, and bacterial and viral infections. Little is known about the effective means by which topical treatment of the nose can strengthen its antioxidant and anti-inflammatory defenses. The present study was undertaken to determine if naturally-occurring plant oils with reported antioxidant activity can provide mechanisms through which upper respiratory protection might occur.

METHODS

Controlled exposure of the upper respiratory system to ozone and nasal biopsy were carried out in healthy human subjects to assess mitigation of the ozone-induced inflammatory response and to assess gene expression in the nasal mucosa induced by a mixture of five naturally-occurring antioxidant oils--aloe, coconut, orange, peppermint and vitamin E. Cells of the BEAS-2B and NCI-H23 epithelial cell lines were used to investigate the source and potential intracellular mechanisms of action responsible for oil-induced anti-inflammatory activity.

RESULTS

Aerosolized pretreatment with the mixed oil preparation significantly attenuated ozone-induced nasal inflammation. Although most oil components may reduce oxidant stress by undergoing reduction, orange oil was demonstrated to have the ability to induce long-lasting gene expression of several antioxidant enzymes linked to Nrf2, including HO-1, NQO1, GCLm and GCLc, and to mitigate the pro-inflammatory signaling of endotoxin in cell culture systems. Nrf2 activation was demonstrated. Treatment with the aerosolized oil preparation increased baseline levels of nasal mucosal HO-1 expression in 9 of 12 subjects.

CONCLUSIONS

These data indicate that selected oil-based antioxidant preparations can effectively reduce inflammation associated with oxidant stress-related challenge to the nasal mucosa. The potential for some oils to activate intracellular antioxidant pathways may provide a powerful mechanism through which effective and persistent cytoprotection against airborne environmental exposures can be provided in the upper respiratory mucosa.

Ambient temperature, air pollution, and heart rate variability in an aging population

Studies show that ambient temperature and air pollution are associated with cardiovascular disease and that they may interact to affect cardiovascular events. However, few epidemiologic studies have examined mechanisms through which ambient temperature may influence cardiovascular function. The authors examined whether temperature was associated with heart rate variability (HRV) in a Boston, Massachusetts, study population and whether such associations were modified by ambient air pollution concentrations. The population was a cohort of 694 older men examined between 2000 and 2008. The authors fitted a mixed model to examine associations between temperature and air pollution and their interactions with repeated HRV measurements, adjusting for covariates selected a priori on the basis of their previous studies. Results showed that higher ambient temperature was associated with decreases in HRV measures (standard deviation of normal-to-normal intervals, low-frequency power, and high-frequency power) during the warm season but not during the cold season. These warm-season associations were significantly greater when ambient ozone levels were higher (>22.3 ppb) but did not differ according to levels of ambient fine (≤2.5 μm) particulate matter. The authors conclude that temperature and ozone, exposures to both of which are expected to increase with climate change, might act together to worsen cardiovascular health and/or precipitate cardiovascular events via autonomic nervous system dysfunction.

Comparative Gene Expression Analysis in the Skeletal Muscles of Dysferlin-deficient SJL/J and A/J Mice

Quantitative real-time polymerase chain reaction (qRT-PCR) analysis was conducted to determine whether or not there are interstrain or site-dependent differences in the gene expression profiles of skeletal muscles in SJL/J and A/J mice as dysferlinopathy models. Upon analysis by qRT-PCR, SJL/J mice showed a trend of increased gene expression level of uncoupling protein 2 in the rectus femoris and longissimus lumborum at 30 weeks of age when dystrophic lesions became histopathologically pronounced. Heme oxygenase 1 and S100 calcium binding protein A4 were upregulated in the rectus femoris, longissimus lumborum and abdominal muscles, in which dystrophic lesions occur more commonly in SJL mice. The gene expression levels of heat shock protein 70 in most muscles of A/J mice were lower than those of BALB/c mice as control. SJL/J mice exhibited a marked lowering of decay-accelerating factor 1/CD55 gene expression level in all studied muscles except for the heart at all ages compared with that of BALB/c mice. This study showed that there were some interstrain differences in the gene expres sion profiles of skeletal muscles between SJL/J and A/J mice. Further investigation is required to reveal whether these alterations of the expression levels are the cause of dystrophic changes or occur subsequent to muscle damage.

Haem arginate infusion stimulates haem oxygenase-1 expression in healthy subjects

BACKGROUND AND PURPOSE

Haem oxygenase 1 (HO-1) is an inducible protein that plays a major protective role in conditions such as ischaemia-reperfusion injury and inflammation. In this study, we have investigated the role of haem arginate (HA) in human male subjects in the modulation of HO-1 expression and its correlation with the GT length polymorphism (GT(n)) in the promoter of the HO-1 gene.

EXPERIMENTAL APPROACH

In a dose-escalation, randomized, placebo-controlled trial, seven healthy male subjects with a homozygous short (S/S) and eight with a long (L/L) GT(n) genotype received intravenous HA. HO-1 protein expression and mRNA levels in peripheral blood monocytes, bilirubin, haptoglobin, haemopexin and haem levels were analysed over a 48 h observation period.

KEY RESULTS

We found that the baseline mRNA levels of HO-1 were higher in L/L subjects, while protein levels were higher in S/S subjects. HA induced a dose-dependent increase in the baseline corrected area under the curve values of HO-1 mRNA and protein over 48 h. The response of HO-1 mRNA was more pronounced in L/L subjects but the protein level was similar across the groups.

CONCLUSIONS AND IMPLICATION

HA is an effective inducer of HO-1 in humans irrespective of the GT(n) genotype. The potential therapeutic application of HA needs to be evaluated in clinical trials.

Interactive effects of antioxidant genes and air pollution on respiratory function and airway disease: a HuGE review

Susceptibility to the respiratory effects of air pollution varies between individuals. Although some evidence suggests higher susceptibility for subjects carrying variants of antioxidant genes, findings from gene-pollution interaction studies conflict in terms of the presence and direction of interactions. The authors conducted a systematic review on antioxidant gene-pollution interactions which included 15 studies, with 12 supporting the presence of interactions. For the glutathione S-transferase M1 gene (GSTM1) (n=10 studies), only 1 study found interaction with the null genotype alone, although 5 observed interactions when GSTM1 was evaluated jointly with other genes (mainly NAD(P)H dehydrogenase [quinone] 1 (NQO1)). All studies on the glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism (n=11) provided some evidence of interaction, but findings conflicted in terms of risk allele. Results were negative for glutathione S-transferase T1 (GSTT1) (n=3) and positive for heme oxygenase 1 (HMOX-1) (n=2). Meta-analysis could not be performed because there were insufficient data available for any specific gene-pollutant-outcome combination. Overall the evidence supports the presence of gene-pollution interactions, although which pollutant interacts with which gene is unclear. However, issues regarding multiple testing, selective reporting, and publication bias raise the possibility of false-positive findings. Larger studies with greater accuracy of pollution assessment and improved quality of conduct and reporting are required.

Air pollution and circulating biomarkers of oxidative stress

Chemical components of air pollutant exposures that induce oxidative stress and subsequent inflammation may be partly responsible for associations of cardiovascular morbidity and mortality with airborne particulate matter and combustion-related pollutant gasses. However, epidemiologic evidence regarding this is limited. An exposure-assessment approach is to measure the oxidative potential of particle mixtures because it is likely that hundreds of correlated chemicals are involved in overall effects of air pollution on health. Oxidative potential likely depends on particle composition and size distribution, especially ultrafine particle concentration, and on transition metals and certain semivolatile and volatile organic chemicals. For health effects, measuring systemic oxidative stress in the blood is one feasible approach, but there is no universal biomarker of oxidative stress and there are many potential target molecules (lipids, proteins, DNA, nitric oxide, etc.), which may be more or less suitable for specific study goals. Concurrent with the measurement of oxidative stress, it is important to measure gene and/or protein expression of endogenous antioxidant enzymes because they can modify relations between oxidative stress biomarkers and air pollutants. Conversely, the expression and activities of these enzymes are modified by oxidative stress. This interplay will likely determine the observed effects of air pollutants on systemic inflammatory and thrombotic mediators and related clinical outcomes. Studies are needed to assess the reliability and validity of oxidative stress biomarkers, evaluate differences in associations between oxidative stress biomarkers and various pollutant measurements (mass, chemical components, and oxidative potential), and evaluate impacts of antioxidant responses on these relations.

Gene-gene interaction in regulatory T-cell function in atopy and asthma development in childhood

BACKGROUND

Regulatory T-cell dysfunction is associated with development of the complex genetic conditions atopy and asthma. Therefore, we hypothesized that single nucleotide polymorphisms in genes involved in the development and function of regulatory T cells are associated with atopy and asthma development.

OBJECTIVE

To evaluate main effects and gene-gene interactions of haplotype tagging single nucleotide polymorphisms of genes involved in regulatory T-cell function-IL6, IL6R, IL10, heme-oxygenase 1 (HMOX1), IL2, Toll-like receptor 2 (TLR2), TGFB1, TGF-beta receptor (TGFBR)-1, TGFBR2, IL2RA, and forkhead box protein 3 (FOXP3)-in relation to atopy and asthma.

METHODS

Single-locus and multilocus associations with total IgE (3rd vs 1st tertile); specific IgE to egg, milk, and indoor allergens; and asthma were evaluated by chi(2) tests and the multifactor dimensionality-reduction method in 3 birth cohorts (Allergenic study).

RESULTS

Multiple statistically significant multilocus associations existed. IL2RA rs4749926 and TLR2 rs4696480 associated with IgE in both age groups tested (1-2 and 6-8 years). TGFBR2 polymorphisms associated with total and specific IgE in both age groups and with asthma. TGFBR2 rs9831477 associated with specific IgE for milk at age 1 to 2 years and indoor allergens at age 6 to 8 years. For milk-specific IgE, interaction between TGFBR2 and FOXP3 polymorphisms was confirmed by logistic regression and consistent in 2 birth cohorts and when stratified for sex, supplying internal replications.

CONCLUSION

Genes involved in the development and function of regulatory T cells, specifically IL2RA, TLR2, TGFBR2, and FOXP3, associate with atopy and asthma by gene-gene interaction. Modeling of multiple gene-gene interactions is important to unravel further the genetic susceptibility to atopy and asthma.

Gene by environment interaction and ambient air pollution

Epidemiologic studies have clearly shown that air pollution is associated with a range of respiratory effects. Recent research has identified oxidative stress as a major biologic pathway underlying the toxic effect of air pollutants. Genetic susceptibility is likely to play a role in response to air pollution. Genes involved in oxidative stress and inflammatory pathways are logical candidates for the study of the interaction with air pollutants. In this article we use the example of asthma, a genetically complex disease, to address the issue of gene by environment interaction with air pollution. The majority of studies have focused on the genes GSTM1, GSTP1, NQO1, and TNF, but the inconsistency of the results prevents the drawing of firm conclusions. The limited sample size of most studies to date make them underpowered for the study of gene by gene interactions. Large consortia of studies with repeated measurements of environmental exposures and clear phenotypic assessments may help determine special environmental triggers and the window of susceptibility in the development of atopy and asthma. The role of gene by gene interactions and epigenetic mechanisms needs to be considered along with gene by environment interactions.

Genetic polymorphism of manganese superoxide dismutase is associated with childhood asthma

OBJECTIVE

Cellular defenses against allergens and reactive oxygen species (ROS) exposure are critical in the pathogenesis of asthma. CD14 is a receptor for various bacterial products, such as lipopolysaccharides (LPS), and is also a mediator of inflammatory processes. Manganese superoxide dismutase (MnSOD) is an ROS scavenger, and myeloperoxidase (MPO) can convert hydrogen peroxide into hypochlorous acid; thus, they are considered to be involved in inflammatory defense. The authors conducted a case-control study to evaluate the susceptibility to childhood asthma based on CD14, MnSOD, and MPO genes.

METHODS

The CD14 -260, MnSOD -9, and MPO -463 genotypes were identified by polymerase chain reactions for 116 asthmatic children and 232 healthy controls. Questionnaires were administered to obtain demographic characteristics. Allergen testing used common Taiwanese aeroallergens.

RESULTS

A higher level of parental education, family history of asthma, incense burning at home, allergen-test positive, and the MnSOD Val-Ala/Ala-Ala genotypes (matched relative risk = 2.0; 95% confidence interval = 1.0-4.2) were significantly associated with childhood asthma. Interactions between CD14, MnSOD, MPO genotypes and allergy status were significantly associated with asthma risk in these children (all p <.001). Furthermore, atopic cases with MnSOD Val-Ala/Ala-Ala (log eosinophil 2.66/mm(3), log total serum immunoglobulin E [IgE] 2.48 IU/ml) or Val-Val (log eosinophil 2.61/mm(3), log total serum IgE 2.63 IU/ml) genotypes had elevated eosinophil counts and total serum IgE levels as compared to nonatopic cases with MnSOD Val-Val genotype (log eosinophil 2.27/mm(3), log total serum IgE 1.83 IU/ml).

CONCLUSIONS

Susceptible MnSOD genotypes might modulate the development of asthma in Taiwanese children.

Childhood incident asthma and traffic-related air pollution at home and school

BACKGROUND

Traffic-related air pollution has been associated with adverse cardiorespiratory effects, including increased asthma prevalence. However, there has been little study of effects of traffic exposure at school on new-onset asthma.

OBJECTIVES

We evaluated the relationship of new-onset asthma with traffic-related pollution near homes and schools.

METHODS

Parent-reported physician diagnosis of new-onset asthma (n = 120) was identified during 3 years of follow-up of a cohort of 2,497 kindergarten and first-grade children who were asthma- and wheezing-free at study entry into the Southern California Children's Health Study. We assessed traffic-related pollution exposure based on a line source dispersion model of traffic volume, distance from home and school, and local meteorology. Regional ambient ozone, nitrogen dioxide (NO(2)), and particulate matter were measured continuously at one central site monitor in each of 13 study communities. Hazard ratios (HRs) for new-onset asthma were scaled to the range of ambient central site pollutants and to the residential interquartile range for each traffic exposure metric.

RESULTS

Asthma risk increased with modeled traffic-related pollution exposure from roadways near homes [HR 1.51; 95% confidence interval (CI), 1.25-1.82] and near schools (HR 1.45; 95% CI, 1.06-1.98). Ambient NO(2) measured at a central site in each community was also associated with increased risk (HR 2.18; 95% CI, 1.18-4.01). In models with both NO(2) and modeled traffic exposures, there were independent associations of asthma with traffic-related pollution at school and home, whereas the estimate for NO(2) was attenuated (HR 1.37; 95% CI, 0.69-2.71).

CONCLUSIONS

Traffic-related pollution exposure at school and homes may both contribute to the development of asthma.

Apoptosis induced by ozone and oxysterols in human alveolar epithelial cells

The mechanism of ozone-induced lung cell injury is poorly understood. One hypothesis is that ozone induces lipid peroxidation and that these peroxidated lipids produce oxidative stress and DNA damage. Oxysterols are lipid peroxides formed by the direct effects of ozone on pulmonary surfactant and cell membranes. We studied the effects of ozone and the oxysterol 5beta,6beta-epoxycholesterol (beta-epoxide) and its metabolite cholestan-6-oxo-3,5-diol (6-oxo-3,5-diol) on human alveolar epithelial type I-like cells (ATI-like cells) and type II cells (ATII cells). Ozone and oxysterols induced apoptosis and cytotoxicity in ATI-like cells. They also generated reactive oxygen species and DNA damage. Ozone and beta-epoxide were strong inducers of nuclear factor erythroid 2-related factor 2, heat shock protein 70, and Fos-related antigen 1 protein expression. Furthermore, we found higher sensitivity of ATI-like cells compared to ATII cells exposed to ozone or treated with beta-epoxide or 6-oxo-3,5-diol. In general the response to the cholesterol epoxides was similar to the effect of ozone. Understanding the response of human ATI-like cells and ATII cells to oxysterols may be useful for further studies, because these compounds may represent useful biomarkers in other diseases.

Air pollution and homocysteine: more evidence that oxidative stress-related genes modify effects of particulate air pollution

BACKGROUND

Ambient particles are associated with cardiovascular events and recently with total plasma homocysteine. High total plasma homocysteine is a risk for human health. However, the biologic mechanisms are not fully understood. One of the putative pathways is through oxidative stress. We aimed to examine whether associations of PM2.5 and black carbon with homocysteine were modified by genotypes including HFE H63D, C282Y, CAT (rs480575, rs1001179, rs2284367, and rs2300181), NQO1 (rs1800566), GSTP1 I105V, GSTM1, GSTT1 (deletion vs. nondeletion), and HMOX-1 (any short vs. both long). We attempted to replicate identified genes in an analysis of heart rate variability and in other outcomes reported in the literature.

METHODS

Study subjects were 1000 white non-Hispanic men in the Boston area, participating in a cohort study of aging. PM2.5, black carbon, total plasma homocysteine, and other covariates were measured at several points in time between 1995 and 2006. We fit mixed models to examine effect modification of genes on associations of pollution with total plasma homocysteine.

RESULTS

Interquartile range increases in PM2.5 and black carbon (7-day moving averages) were associated with 1.5% (95% confidence interval = 0.2% to 2.8%) and 2.2% (0.6% to 3.9%) increases in total plasma homocysteine, respectively. GSTT1 and HFE C282Y modified effects of black carbon on total plasma homocysteine, and HFE C282Y and CAT (rs2300181) modified effects of PM2.5 on homocysteine. Several genotypes marginally modified effects of PM2.5 and black carbon on various endpoints. All genes with significant interactions with particulate air pollution had modest main effects on total plasma homocysteine.

CONCLUSIONS

: Effects of PM2.5 and black carbon on various endpoints appeared to be mediated by genes related to oxidative stress pathways.

Particulate matter and atherosclerosis: role of particle size, composition and oxidative stress

Air Pollution has been associated with significant adverse health effects leading to increased morbidity and mortality. Cumulative epidemiological and experimental data have shown that exposure to air pollutants lead to increased cardiovascular ischemic events and enhanced atherosclerosis. It appears that these associations are much stronger with the air particulate matter (PM) component and that in urban areas, the smaller particles could be more pathogenic, as a result of their greater propensity to induce systemic prooxidant and proinflammatory effects. Much is still unknown about the toxicology of ambient particulates as well as the pathogenic mechanisms responsible for the induction of adverse cardiovascular health effects. It is expected that better understanding of these effects will have large implications and may lead to the formulation and implementation of new regulatory policies. Indeed, we have found that ultrafine particles (<0.18 mum) enhance early atherosclerosis, partly due to their high content in redox cycling chemicals and their ability to synergize with known proatherogenic mediators in the promotion of tissue oxidative stress. These changes take place in parallel with increased evidence of phase 2 enzymes expression, via the electrophile-sensitive transcription factor, p45-NFE2 related transcription factor 2 (Nrf2). Exposure to ultrafine particles also results in alterations of the plasma HDL anti-inflammatory function that could be indicative of systemic proatherogenic effects. This article reviews the epidemiological, clinical and experimental animal evidence that support the association of particulate matter with atherogenesis. It also discusses the possible pathogenic mechanisms involved, the physicochemical variables that may be of importance in the greater toxicity exhibited by a small particle size, interaction with genes and other proatherogenic factors as well as important elements to consider in the design of future mechanistic studies.Extensive epidemiological evidence supports the association of air pollution with adverse health effects 123. It is increasingly being recognized that such effects lead to enhanced morbidity and mortality, mostly due to exacerbation of cardiovascular diseases and predominantly those of ischemic character 4. Indeed, in addition to the classical risk factors such as serum lipids, smoking, hypertension, aging, gender, family history, physical inactivity and diet, recent data have implicated air pollution as an important additional risk factor for atherosclerosis. This has been the subject of extensive reviews 56 and a consensus statement from the American Heart Association 7. This article reviews the supporting epidemiological and animal data, possible pathogenic mechanisms and future perspectives.

Bibliography. Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 November 2007 and 31 October 2008 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

Gene by environment interaction in asthma

Marked international differences in rates of asthma and allergies and the importance of family history highlight the primacy of interactions between genetic variation and the environment in asthma etiology. Environmental tobacco smoke (or secondhand smoke), ambient air pollutants, and endotoxin and/or other pathogen-associated molecular patterns are the ambient exposures studied most frequently for interactions with genetic polymorphisms in asthma. To date, results from the literature remain inconclusive. Most published studies are underpowered to study interactions between genetic polymorphisms and ambient exposures, each with weak effects. Strategies to increase power include cooperation across studies to increase sample sizes and improve measures of both exposure and asthma phenotypes. Genome-wide association studies hold promise for identifying unexpected gene environment interactions, but given the statistical power issues, candidate gene association studies will remain important. New tools are enabling the study of epigenetic mechanisms for environmental interactions.

Heme oxygenase-1 microsatellite polymorphism and haplotypes are associated with the development of acute respiratory distress syndrome

OBJECTIVE

Heme oxygenase-1 (HO-1) acts in cytoprotection against acute lung injury. The polymorphic (GT)n repeat in the HO-1 gene (HMOX1) promoter regulates HMOX1 expression. We investigated the associations of HMOX1 polymorphisms with acute respiratory distress syndrome (ARDS) risk and plasma HO-1 levels.

DESIGN

Unmatched, nested case-control study.

SETTING

Academic medical center.

PATIENTS

Consecutive patients with ARDS risk factors upon ICU admission were prospectively enrolled. Cases were 437 Caucasians who developed ARDS and controls were 1,014 Caucasians who did not.

MEASUREMENTS AND RESULTS

We genotyped the (GT)n polymorphism and three tagging single nucleotide polymorphisms (tSNPs) in 1,451 patients, and measured the plasma HO-1 levels in 106 ARDS patients. We clustered the (GT)n repeats into: S-allele (<24 repeats), M-allele (24-30 repeats) and L-allele (> or = 31 repeats). We found that longer (GT)n repeats were associated with reduced ARDS risk (Ptrend = 0.004 for both alleles and genotypes), but no individual tSNP was associated with ARDS risk. HMOX1 haplotypes were significantly associated with ARDS risk (global test, P = 0.016), and the haplotype S-TAG was associated with increased ARDS risk (OR, 1.75; 95% CI, 1.15-2.68; P = 0.010). Intermediate-phenotype analysis showed longer (GT)n repeats were associated with higher plasma HO-1 levels (Ptrend = 0.019 for alleles and 0.027 for genotypes).

CONCLUSIONS

Longer (GT)n repeats in the HMOX1 promoter are associated with higher plasma HO-1 levels and reduced ARDS risk. The common haplotype S-TAG is associated with increased ARDS risk. Our results suggest that HMOX1 variation may modulate ARDS risk through the promoter microsatellite polymorphism.

Tobacco smoking, fruit and vegetable intake modify association between -21A>T polymorphism of catalase gene and risk of bronchial asthma

Although oxidative stress is a cardinal feature of bronchial asthma, the role of interactions between environmental oxidant/antioxidant exposures and antioxidant genes in asthma aetiology has yet to be determined. The present study was conducted to investigate whether two common polymorphisms -21A > T and -262C > T of catalase (CAT) gene are associated with susceptibility to asthma in a Russian population and to test the hypothesis that the asthma risk attributed to CAT genotypes could be dependent on both oxidant (tobacco smoking) and antioxidant (fruit and vegetable intake) exposures. A total of 429 unrelated Russian individuals from Central Russia were recruited in the study, including 215 asthmatics and 214 sex- and age-matched healthy controls. Genotyping analysis for the CAT gene polymorphisms was performed by PCR-RFLP assays. The frequencies of both allele -21A (OR 0.73 95%CI 0.55-0.96 p = 0.03) and -21AA CAT genotype (OR 0.42 95%CI 0.23-0.76 p = 0.004) were higher among asthmatics than among healthy controls. The frequency of -21AA genotype of the CAT gene was significantly higher in patients with allergic (OR 0.47 95%CI 0.25-0.92 p = 0.024) and nonallergic (OR 0.32 95%CI 0.14-0.71 p = 0.004) asthma in comparison with controls (at the Bonferroni corrected p value less than 0.025). Polymorphisms -21A > T and -262C > T of the catalase gene were in a positive linkage disequilibrium (p < 0.0001). Smokers who carried -21AA genotype had an increased risk of nonallergic asthma (p = 0.002), whereas nonsmoker carriers of this genotype did not have the risk of any variant of the disease. Notably, no association of CAT genotype -21AA with asthma was found in high fruit and vegetable consumers, whereas low fruit and vegetable consumers (one time per day or less often) possessing this genotype were at increased risk of both allergic (p = 0.013) and nonallergic (p = 0.008) asthma. This is the first study reporting an association of polymorphism -21A > T of the catalase gene with allergic and nonallergic asthma. We also found, for the first time, that cigarette smoking and fruit and vegetable intakes have potentially inverse modifying influences on the asthma risk in individuals with -21AA CAT genotype and that the gene-environment interactions that were found support the biologic plausibility of catalase gene for the development of bronchial asthma.

Roles of arginase variants, atopy, and ozone in childhood asthma

BACKGROUND

Arginases (encoded by ARG1 and ARG2 genes) might play an important role in asthma pathogenesis through effects on nitrosative stress. Arginase expression is upregulated in asthma and varies with T(H)2 cytokine levels and oxidative stress.

OBJECTIVE

We aimed to examine whether variants in these genes are associated with asthma and whether atopy and exposures to smoking and air pollution influence the associations.

METHODS

Among non-Hispanic and Hispanic white participants of the Children's Health Study (n = 2946), we characterized variation in each locus (including promoter region) with 6 tag single nucleotide polymorphisms for ARG1 and 10 for ARG2. Asthma was defined by parental report of physician-diagnosed asthma at study entry.

RESULTS

Both ARG1 and ARG2 genetic loci were significantly associated with asthma (global locus level P = .02 and .04, respectively). Compared with the most common haplotype within each locus, 1 ARG1 haplotype was associated with reduced risk (odds ratio [OR] per haplotype copy, 0.55; 95% CI, 0.36-0.84), and 1 ARG2 haplotype was associated with increased risk (OR per haplotype copy, 1.35; 95% CI, 1.04-1.76) of asthma. The effect of the ARG1 haplotype that was significantly associated with asthma varied by the child's history of atopy and ambient ozone (P(interaction) = .04 and .02, respectively). Among atopic children living in high-ozone communities, those carrying the ARG1 haplotype had reduced asthma risk (OR per haplotype copy, 0.12; 95% CI, 0.04-0.43; P(heterogeneity) across atopy/ozone categories = .008).

CONCLUSIONS

ARG1 and ARG2 loci are associated with childhood asthma. The association between ARG1 variation and asthma might depend on atopy and ambient ozone levels.

Glutathione-S-transferase (GST) P1, GSTM1, exercise, ozone and asthma incidence in school children

BACKGROUND

Because asthma has been associated with exercise and ozone exposure, an association likely mediated by oxidative stress, we hypothesised that glutathione-S-transferase (GST)P1, GSTM1, exercise and ozone exposure have interrelated effects on the pathogenesis of asthma.

METHODS

Associations of the well characterised null variant of GSTM1 and four single nucleotide polymorphisms (SNPs) that characterised common variation in the GSTP1 locus with new onset asthma in a cohort of 1610 school children were examined. Children's exercise and ozone exposure were classified using participation in team sports and community annual average ozone levels, respectively.

RESULTS

A two SNP model involving putatively functional variants (rs6591255, rs1695 (Ile105Va)) best captured the association between GSTP1 and asthma. The risk of asthma was lower for those with the Val allele of Ile105Val (hazard ratio (HR) 0.60, 95% CI 0.4 to 0.8) and higher for the variant allele of rs6591255 (HR 1.40, 95% CI 1.1 to 1.9). The risk of asthma increased with level of exercise among ile(105) homozygotes but not among those with at least one val(105) allele (interaction p value = 0.02). The risk was highest among ile(105) homozygotes who participated in >or=3 sports in the high ozone communities (HR 6.15, 95% CI 2.2 to 7.4). GSTM1 null was independently associated with an increased risk of asthma and showed little variation with air pollution or GSTP1 genotype. These results were consistent in two independent fourth grade cohorts recruited in 1993 and 1996.

CONCLUSION

Children who inherit a val(105) variant allele may be protected from the increased risk of asthma associated with exercise, especially in high ozone communities. GSTM1 null genotype was associated with an increased risk of asthma.

Cardioprotection by hypoxia-inducible factor 1 alpha transfection in skeletal muscle is dependent on haem oxygenase activity in mice

AIMS

The present study investigates whether the cardioprotection achieved by gene delivery of hypoxia-inducible factor-1 alpha (HIF-1 alpha) depends on the downstream factor haem oxygenase (HMOX)-1.

METHODS AND RESULTS

Immortalized cardiomyocytes (HL-1 cells) were transfected with HIF-1 alpha or HMOX-1 and injured with hydrogen peroxide (H(2)O(2)), and death was evaluated by trypan blue staining. Quadriceps muscles of mice were treated with DNA for HIF-1 alpha and HMOX-1, or sham-treated and electroporated, and 3 days later, hearts were isolated and subjected to global ischaemia and reperfusion. Some HIF-1 alpha- and sham-treated mice received the HMOX blocker zinc deuteroporphyrin 2,4-bis-glycol (ZnBG) (n = 6-8 in each group). HL-1 cells were stimulated with bilirubin or the carbon monoxide donor CORM-2 before injury with H(2)O(2). HL-1 cells which were transfected with HIF-1 alpha or HMOX-1 had an increased survival to H(2)O(2)-induced injury compared with empty vector (n = 10-12 per group; P < 0.01 for both). When HMOX-1-luciferase reporter mice were treated with HIF-1 alpha in the quadriceps muscle, increased luciferase activity was found locally, but nowhere else. Mice pre-treated with HIF-1 alpha or HMOX-1 had a reduced infarct size, improved post-ischaemic function, and increased serum bilirubin (P < 0.05). ZnBG inhibited all these effects afforded by HIF-1 alpha. Stimulation of HL-1 cells with bilirubin and CORM-2 reduced cell death evoked by H(2)O(2) (P < 0.05 for both, n = 11-15 in each group).

CONCLUSION

HIF-1 alpha and HMOX-1 provided protection against H(2)O(2)-induced damage in HL-1 cells. Remote gene delivery of HIF-1 alpha afforded cardioprotective effects. These were dependent on HMOX activity, as an HMOX blocker abolished the effects, and they were mimicked by pre-treatment with HMOX-1. Downstream to HMOX-1, bilirubin as well as carbon monoxide may be organ effectors.