Heme oxygenase 1 polymorphism, occupational vapor, gas, dust, and fume exposure and chronic obstructive pulmonary disease in a Danish population-based study.

Objectives The number of dinucleotide repeats (GT) nmodulate expression of heme oxygenase 1 (HMOX1), a stress response gene. Multiple repeats might affect chronic obstructive pulmonary disease (COPD) susceptibility. We aimed to investigate the association of this polymorphism with COPD and its interaction with occupational exposures (vapor, gas, dust, or fumes). Methods This population-based cross-sectional study included 4703 Danes, aged 45-84 years. HMOX1 (GT) nwas genotyped and grouped as short: ≤26, medium: 27-32 and long: ≥33 alleles. COPD was defined by the lower limit of normal (2.5 thFEV 1/FVC and FEV 1centiles). Occupational exposure was defined as ever exposed to vapor, gas, dust, or fume in expert-selected jobs. Associations were analyzed by adjusted mixed logistic regression. Results The population included 6% with COPD, 48% who had smoked ≥10 pack-years, and 46% with occupational exposure. HMOX1 was genotyped in 4423 participants. The adjusted odds ratio (OR) for the association between HMOX1 long allele and COPD was 1.75 [95% confidence interval (CI) 1.18-2.60]. An interaction was evident between HMOX1 long allele and occupational exposure, OR 2.38 (95% CI 1.04-5.46), versus HMOX1 short/medium without exposure. Analyses were replicated in another cohort, aged 20-44 years, N=1168, including 3% with COPD, 25% who had smoked ≥10 pack-years and 20% with occupational exposure. No associations were seen between COPD and HMOX1 long allele here. Conclusions Long alleles in HMOX1 alone and in interaction with occupational exposure seem to be associated with COPD. Failure to replicate data may be due to premature age for COPD development and low occupational exposure prevalence. We propose this long allele may be a genetic contributor to the COPD pathogenesis.

Risk factors for incident asthma and COPD in a cohort of young adults.

INTRODUCTION: The aim of the study was to describe potential shared risk factors for incident asthma and COPD in a population-based, 9-year follow-up study. METHODS: From a cohort of 1191 individuals, aged 20-44, who participated in baseline survey including spirometry, bronchial challenge, and skin prick test (SPT) 742 subjects (62%) were reexamined at follow-up in 2012-2014. RESULTS: A total of 27 incident cases of asthma and 22 cases of COPD were identified at follow-up corresponding to an incidence rate of 5.8 (95% CI 3.9-8.4) and 3.5 (2.2-5.3) per 1000 person years, respectively. Among the identified COPD cases a total of 12 were Asthma-COPD Overlap Syndrome (ACOS). Atopy defined by positive SPT was a risk factor for asthma in males (OR 7.54; 95% CI 1.24-45.90), whereas risk factors in females were nasal allergy (3.81; 1.20-12.11), FEV1 <100% predicted (3.96; 1.07-14.62) and parental asthma (3.06; 1.00-9.40). Risk factors for COPD in males were bronchial hyperresponsiveness (23.13; 1.41-380.50) and FEV1 <100% predicted (all male cases had FEV1 <100% predicted) and in females current smoking (3.34; 1.16-9.59) and asthma at baseline (5.21; 1.48-18.34). CONCLUSIONS: No shared risk factors for incident asthma and COPD were found. Despite low power when stratifying by sex risk factors for incident asthma and COPD emphasize considerable gender differences.

The population attributable fraction of occupational COPD among Danish women.

The PAF of occupational COPD among Danish women http://ow.ly/CEmy308XEgl.

Are allergen batch differences and the use of double skin prick test important?

BACKGROUND: Skin prick tests (SPT) are widely used both in clinical diagnostics and in research. The standardization of allergen extracts is well documented to be crucial for the validity of SPT, whereas less emphasis has been placed on reproducibility and the SPT procedure itself. The objectives of this study are to clarify how the double skin prick test procedure influence the sensitivity and specificity of the test and to analyse the differences in weal size in skin prick tests between two batches of allergen extracts from the same vendor. METHODS: The association between rhinitis and SPT was assessed among 1135 persons from a general population sample. SPT was performed twice with 10 common aeroallergens. In a subsample of 90 persons SPT was performed simultaneously with five of the allergens using different batches. RESULTS: Thirty percent had at least one positive SPT. Among asthmatics this number was 62%. Only minor differences were seen between the sizes of two weals from the same batch. A second SPT with the same batch did not change the association between rhinitis and sensitization. When performing SPT with two different batches disagreement was observed in 2% (Birch) to 11% (Cat) of the subjects. CONCLUSIONS: Performing SPT twice with the same allergen batch does not enhance the validity of the test, and value of double testing can be questioned. Considerable differences in SPT response with different batches from the same manufacturer were observed. Thus inter batch differences in allergen extracts might be a source of variability.

Occupational COPD among Danish never-smokers: a population-based study.

Occupational exposures have been shown to be risk factors for chronic obstructive pulmonary disease (COPD) among never-smokers. In a Danish population-based cohort, we analysed this association and the population attributable fraction. The study population (N=1575) was aged 45-84, COPD was defined by lung function measurements and the method of lower limit of normal (LLN), and occupational exposure was assessed by questionnaire and expert judgement. Furthermore, the estimates additionally were provided according to the Global Initiative for Chronic Obstructive Lung Diseases. More than a threefold increased risk (LLN OR=3.69 (95% CI 1.36 to 10.04) was found for occupational exposure to vapour, gas, dust and fumes (predominantly organic dust) in this never-smoking population, with a corresponding 48% (95% CI 30% to 65%) population attributable fraction among never-smokers.

Occupational Chronic Obstructive Pulmonary Disease in a Danish Population-Based Study.

The aim was to explore the impact of occupation on chronic obstructive pulmonary disease (COPD) in a cross-sectional population-based study among subjects aged 45 to 84 years. In a stratified sampling 89 general practitioners practices (GPP) in Denmark recruited 3106 males and 1636 females through the Danish Civil Registration System. COPD was defined by spirometry by the 2.5(th)-centile Lower Limit of Normal of FEV1 and FEV1/FVC. Information about smoking, occupational exposure and the respective occupations were obtained from questionnaires. Occupations followed the Danish adaptation of The International Standard Classification of Occupations, revision 1988 (DISCO-88). Exposure to vapour, gas, dust (organic and inorganic), and fume (VGDF) in each occupation (yes/no) was evaluated by two independent specialist in occupational medicine. Exposures were divided in no, low, medium, and high exposure as 0, < 5, 5-14, and ≥ 15 years in the job, respectively. Data was analysed by a mixed random effect logistic regression model. The age-standardised COPD study prevalence was 5.0%. Of 372 DISCO-88 codes 72 were identified with relevant exposure to VGDF. 46% of the participants reported at least one occupation with VGDF exposure. Adjusted for smoking, age, sex, and GPP a dose-dependent association of COPD was found among workers in jobs with high organic dust exposure, with OR 1.56 (95% CI 1.09-2.24). Restricted to agriculture the OR was 1.59 (95% CI: 1.08-2.33). No association was observed for workers in jobs with inorganic dust, fume/gas, or vapour exposures. In summary, occupational organic dust exposure was associated to the prevalence of COPD.

Genetic polymorphisms in antioxidative enzymes are associated to forced expiratory volume in 1 s (FEV1) in smokers independently of asthma.

INTRODUCTION: In this study, we hypothesised that the genotypes coding for low antioxidative enzyme activity are associated with asthma and reduced lung function. METHODS: Using the European Community Respiratory Health Survey protocol, we enlisted 1091 Danish subjects in this cross-sectional study. Asthma phenotypes were defined as asthma symptoms in combination with steroid usage, bronchial hyperresponsiveness and atopy. These phenotypes and lung function were analysed with respect to glutathione peroxidase, GPX1 (Pro198Leu, rs1050450), manganese superoxide dismutase, SOD2 (Ala16Val, rs4880) and three glutathione S-transferases; GSTP1 (Ile105Val, rs1695), GSTT1 (gene copy number) and GSTM1 (gene copy number). RESULTS: We found no associations between these genotypes and the asthma phenotypes. For the 201 subjects identified as current smokers and recruited via random sampling, an association was seen between increasing number of genotypes coding for high antioxidative enzyme activity (GPX1 Pro/Pro, SOD2 Val/Val, GSTP1 Ile/Ile, GSTT1 two copies, GSTM1 two copies) and forced expiratory volume in 1 s (FEV1%) predicted. The increase in FEV1% predicted was 2.0% (95% confidence interval 0.3-3.8) per genotype. There was no identified significance for the inverse association between FEV1% predicted and number of genotypes coding for low antioxidative enzyme activity. CONCLUSION: The present study does not support the hypothesis that asthma is associated with genotypes of these major antioxidative enzymes. However, we speculate that since we see an impact of these genotypes on lung function in young adult smokers, polymorphisms in antioxidative enzymes may contribute to the range of susceptibility of smokers have to Chronic obstructive lung disease.

Differences in associations between markers of antioxidative defense and asthma are sex specific.

BACKGROUND: Lungs are exposed to high levels of oxygen, air pollutants, and smoke, all of which stimulate the production of reactive oxygen species (ROS). In addition, inflammatory cells produce ROS, and thus there may be increased demand for antioxidants, including antioxidant enzymes, in inflammatory lung diseases such as asthma. Sex-specific differences have been noted for asthma, which in postpubertal subjects is predominantly found in females. These sex-specific differences may be associated with differences on the molecular level as well. OBJECTIVE: The aim of this cross-sectional study was to examine associations between markers of antioxidative defense and asthma, and to investigate whether these associations were different between women and men. METHODS: Based on the European Community Respiratory Health Survey protocol, subjects were enrolled in a study of asthma risk factors. The multicenter study was conducted in 5 west Danish counties between 2003 and 2006, and the subjects were recruited as a case-enriched random sample of 10,000 Danish inhabitants aged 20 to 44 years selected by their civil registration number. Participants were identified by positive answers to asthma questions on a screening questionnaire, random sampling, or both. Serum selenium concentrations and antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase [GPX], glutathione reductase [GR], and glucose-6-phosphate dehydrogenase [G6PD]) in erythrocytes were measured. Asthma was defined as either current asthma symptoms with bronchial hyperresponsiveness (BHR) or a continuous asthma score based on 8 questions. RESULTS: A total of 1191 mostly white women and men (mean [SD] age, 34.0 [7.1] and 35.1 [7.1] years, respectively) were enrolled in the study. Current asthma symptoms were present in 29.9% (200/670) of women and 22.5% (117/521) of men, with women reporting more positive answers (51.1% vs 40.9%, respectively; P < 0.01) to asthma questions. Serum selenium concentrations were measured in 1151 subjects (640 women, 511 men), and antioxidant enzyme activities were measured in 295 subjects (161 women, 134 men). Women had higher enzyme activities of most antioxidant enzymes (GPX, P = 0.006; GR, P < 0.001; and G6PD, P = 0.009) than did men. Although the serum selenium concentration was inversely associated with asthma in both sexes, there was a female preponderance, with 3.5% lower serum selenium in subjects with current asthma symptoms with BHR (n = 77) compared with controls (n = 287). GR activity was associated with asthma in men, with 5.7% higher enzyme activity in subjects with current asthma symptoms with BHR (n = 14) compared with controls (n = 77). However, a significant interaction with gender was observed for analyses of GR (P = 0.02), but not for analyses of selenium. CONCLUSIONS: In this study of asthma risk factors, women had higher levels of enzyme activities than did men in a randomly selected Danish population, and sex-specific differences were found in the associations between markers of antioxidative defense and asthma.

Sex determines the influence of smoking and gene polymorphism on glutathione peroxidase activity in erythrocytes.

OBJECTIVE: Glutathione peroxidase 1 (GPX1) is one of the major oxidative enzymes. Our aim was to characterize factors influencing its activity and to determine whether or not the activity is associated with asthma. MATERIAL AND METHODS: Serum selenium concentration was measured, GPX1 polymorphisms were genotyped and smoking history was obtained in a Danish population-derived case-base cohort of 1,191 subjects designed to evaluate risk factors for asthma. GPX1 activity was measured in 134 male and 164 female subjects equally distributed according to genotype of GPX1. Among these subjects, 82 (28 %) had doctor-diagnosed asthma. RESULTS: The average serum selenium concentration was too low for optimal enzyme activity (mean (SE), 83.4 (0.76) ng/mL). GPX1 activity in men was lower than in women, 52.6 (0.66) and 56.4 (0.59) U/g protein, respectively (p<0.001). In men, activity was positively associated with serum selenium concentration (p = 0.005) and negatively associated with both active smoking (p = 0.009) and exposure to environmental tobacco smoke (p = 0.02). In women, activity was associated with genotypes with 59.2 (1.4), 56.0 (1.4) and 54.2 (1.4) U/g protein in the homozygote wild-type, the heterozygote and the homozygote variant type, respectively (p = 0.001). Doctor-diagnosed asthma was unrelated to GPX1 activity in either sex. CONCLUSION: Determinants for activity in the oxidative enzyme GPX1 show marked differences between the sexes, but the activity is not associated with asthma. Sex ought to be taken into consideration when analysing the activity of the enzyme.

CD4dimCD25bright Treg cell frequencies above a standardized gating threshold are similar in asthmatics and controls.

BACKGROUND: Thymus selected CD4(+)CD25(bright) natural regulatory Treg cells expressing FOXP3 may contribute to control of immune responses. No unique markers have been available to identify and characterize Treg. We present a gating strategy that allows enumeration of Treg on the basis of CD4 and CD25 and investigate whether asthmatics have fewer Treg than controls. METHODS: Asthmatics and controls were selected from responses to a mailed questionnaire. CD25, CD4, HLA DR, and appropriate isotypes were recorded by flow cytometry. RESULTS: The CD4 T cells expressing most CD25 are a separate population expressing FOXP3 and lower levels of CD4 and CD127. On a CD4 CD25 dot-plot, the CD4 MFI of Treg for 152 participants was calculated to be 0.83 +/- 0.043*MFI of CD25(bright) T-cells. CD4(dim)CD25(bright) T cells in a rectangular gate with a CD4 MFI