Association between lung function and dyspnoea and its variation in the multinational Burden of Obstructive Lung Disease (BOLD) study

BACKGROUND

Dyspnoea is a common symptom of respiratory disease. However, data on its prevalence in general populations and its association with lung function are limited and are mainly from high-income countries. The aims of this study were to estimate the prevalence of dyspnoea across several world regions, and to investigate the association of dyspnoea with lung function.

METHODS

Dyspnoea was assessed, and lung function measured in 25,806 adult participants of the multinational Burden of Obstructive Lung Disease study. Dyspnoea was defined as ≥2 on the modified Medical Research Council (mMRC) dyspnoea scale. The prevalence of dyspnoea was estimated for each of the study sites and compared across countries and world regions. Multivariable logistic regression was used to assess the association of dyspnoea with lung function in each site. Results were then pooled using random-effects meta-analysis.

RESULTS

The prevalence of dyspnoea varied widely across sites without a clear geographical pattern. The mean prevalence of dyspnoea was 13.7 % (SD=8.2 %), ranging from 0 % in Mysore (India) to 28.8 % in Nampicuan-Talugtug (Philippines). Dyspnoea was strongly associated with both spirometry restriction (FVC

CONCLUSION

The prevalence of dyspnoea varies substantially across the world and is strongly associated with lung function impairment. Using the mMRC scale in epidemiological research should be discussed.

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Key Words

• Breathlessness
• Dyspnoea
• Lung function
• Spirometry

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MESH Headings Collapse

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Occupational exposure to particulate matter and staff sickness absence on the London underground

The London Underground (LU) employs over 19,000 staff, some of whom are exposed to elevated concentrations of particulate matter (PM) within the network. This study quantified the occupational exposure of LU staff to subway PM and investigated the possible association with sickness absence (SA). A job exposure matrix to quantify subway PM2.5 staff exposure was developed by undertaking measurement campaigns across the LU network. The association between exposure and SA was evaluated using zero-inflated mixed-effects negative binomial models. Staff PM2.5 exposure varied by job grade and tasks undertaken. Drivers had the highest exposure over a work shift (mean: 261 µg/m3), but concentrations varied significantly by LU line and time the train spent subway. Office staff work in office buildings separate to the LU network and are unexposed to occupational subway PM2.5. They were found to have lower rates of all-cause and respiratory infection SA compared to non-office staff, those who work across the LU network and are occupational exposed to subway PM2.5. Train drivers on five out of eight lines showed higher rates of all-cause SA, but no dose-response relationship was seen. Only drivers from one line showed higher rates of SAs from respiratory infections (incidence rate ratio: 1.24, 95% confidence interval 1.10-1.39). Lower-grade customer service (CS) staff showed higher rates of all-cause and respiratory infection SA compared to higher grade CS staff. Doctor-certified chronic respiratory and cardiovascular SAs were associated with occupational PM2.5 exposure in CS staff and drivers. While some groups with higher occupational exposure to subway PM reported higher rates of SA, no evidence suggests that subway PM is the main contributing factor to SA. This is the largest subway study on health effects of occupational PM2.5 exposure and may have wider implications for subway workers, contributing to safer working environments.

High prevalence of TB multimorbidity among adults of a tertiary hospital in Sierra Leone: a cross-sectional study

OBJECTIVE

Tuberculosis (TB) is a leading cause of death globally, with approximately 1.5 million deaths in 2020. TB often coexists with chronic communicable and non-communicable diseases, but data to determine the extent of comorbid diseases are limited. In this study, we aimed to assess the prevalence of TB multimorbidity and its risk factors in a tertiary hospital in Sierra Leone. This is a cross-sectional study of 240 adults with microbiologically-confirmed TB at Connaught Hospital in Freetown, between March and May 2022. Logistic regression analysis was used to identify factors associated with TB multimorbidity.

RESULTS

The mean age of the patients was 37 years. More than two-thirds were males and about the same number had two or more chronic diseases. The most common were hypertension (47.9%) and diabetes (24.2%). Patients under 35 years of age were less likely to have TB multimorbidity (< 25 years: adjusted OR 0.07, 95%CI 0.01-0.6; 25-34 years: adjusted OR 0.2, 95%CI 0.01-0.9). We report a high prevalence of comorbid diseases among TB patients in the largest treatment center in Sierra Leone, with hypertension and diabetes being the most common. These findings support the current call for addressing comorbid non-communicable diseases in TB patients through integrated care.

Biomarkers of the L-Arginine/Dimethylarginine/Nitric Oxide Pathway in People with Chronic Airflow Obstruction and Obstructive Sleep Apnoea

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea (OSA) are common chronic diseases that are associated with chronic and intermittent hypoxemia, respectively. Patients affected by the overlap of COPD and OSA have a particularly unfavourable prognosis. The L-arginine/nitric oxide (NO) pathway plays an important role in regulating pulmonary vascular function. Asymmetric (ADMA) and symmetric dimethylarginine (SDMA) interfere with NO production.

METHODS

We analysed the serum concentrations of ADMA, SDMA, L-arginine, L-citrulline, and L-ornithine in a large sample of the Icelandic general population together with chronic airflow obstruction (CAO), a key physiological marker of COPD that was assessed by post-bronchodilator spirometry (FEV1/FVC < LLN). OSA risk was determined by the multivariable apnoea prediction (MAP) index.

RESULTS

713 individuals were analysed, of whom 78 (10.9%) showed CAO and 215 (30%) had MAP > 0.5. SDMA was significantly higher in individuals with CAO (0.518 [0.461-0.616] vs. 0.494 [0.441-0.565] µmol/L; p = 0.005), but ADMA was not. However, ADMA was significantly associated with decreasing FEV1 percent predicted among those with CAO (p = 0.002). ADMA was 0.50 (0.44-0.56) µmol/L in MAP ≤ 0.5 versus 0.52 (0.46-0.58) µmol/L in MAP > 0.5 (p = 0.008). SDMA was 0.49 (0.44-0.56) µmol/L versus 0.51 (0.46-0.60) µmol/L, respectively (p = 0.004). The highest values for ADMA and SDMA were observed in individuals with overlap of CAO and MAP > 0.5, which was accompanied by lower L-citrulline levels.

CONCLUSIONS

The plasma concentrations of ADMA and SDMA are elevated in COPD patients with concomitant intermittent hypoxaemia. This may account for impaired pulmonary NO production, enhanced pulmonary vasoconstriction, and disease progression.

Prevalence and determinants of chronic respiratory diseases in adults in rural Sudan

BACKGROUND: Chronic respiratory diseases (CRDs) greatly contribute to worldwide mortality. Despite new data emerging from Africa, prevalence estimates and determinants of CRDs in rural settings are limited. This study sought to extend the existing research conducted in urban Sudan by conducting a rural comparison.METHODS: Participants aged ≥18 years (n = 1,850), living in rural Gezira State completed pre-and post-bronchodilator spirometry and a questionnaire. Prevalence of respiratory symptoms and spirometric abnormalities were reported. Regression analyses were used to identify risk factors for CRDs.RESULTS: Prevalence of chronic airflow obstruction (CAO) was 4.1% overall and 5.5% in those aged ≥40 years. Reversibility was seen in 6.4%. Low forced vital capacity (FVC) was seen in 58.5%, and at least one respiratory symptom was present in 40.7% of the participants. CAO was more common among people aged 60-69 years (OR 2.07, 95% CI 1.13-3.82) and less common among highly educated participants (OR 0.50, 95% CI 0.27-0.93). Being underweight was associated with lower FVC (OR 3.07, 95% CI 2.24-4.20).CONCLUSIONS: A substantial burden of CRD exists among adults in rural Sudan. Investment in CRD prevention and management strategies is needed.

Prevalence and determinants of chronic respiratory diseases in adults in Sudan

BACKGROUND: Chronic respiratory diseases (CRDs) are considered a significant cause of morbidity and mortality worldwide, although data from Africa are limited. This study aimed to determine the prevalence and determinants of CRDs in Khartoum, Sudan.METHODS: Data were collected from 516 participants aged ≥40 years, who had completed a questionnaire and undertook pre- and post-bronchodilator spirometry testing. Trained field workers administered the questionnaires and conducted spirometry. Survey-weighted prevalence of respiratory symptoms and spirometric abnormalities were estimated. Regression analysis models were used to identify risk factors for chronic lung diseases.RESULTS: Using the Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III) reference equations, the prevalence of chronic airflow obstruction (CAO) was 10%. The main risk factor was older age, 60-69 years (OR 3.16, 95% CI 1.20-8.31). Lower education, high body mass index and a history of TB were also identified as significant risk factors. The prevalence of a low forced vital capacity (FVC) using NHANES III was 62.7% (SE 2.2) and 11.3% (SE 1.4) using locally derived values.CONCLUSION: The prevalence of spirometric abnormality, mainly low FVC, was high, suggesting that CRD is of substantial public health importance in urban Sudan. Strategies for the prevention and control of these problems are needed.

Clinical standards for the assessment, management and rehabilitation of post-TB lung disease

BACKGROUND: Increasing evidence suggests that post-TB lung disease (PTLD) causes significant morbidity and mortality. The aim of these clinical standards is to provide guidance on the assessment and management of PTLD and the implementation of pulmonary rehabilitation (PR).METHODS: A panel of global experts in the field of TB care and PR was identified; 62 participated in a Delphi process. A 5-point Likert scale was used to score the initial ideas for standards and after several rounds of revision the document was approved (with 100% agreement).RESULTS: Five clinical standards were defined: Standard 1, to assess patients at the end of TB treatment for PTLD (with adaptation for children and specific settings/situations); Standard 2, to identify patients with PTLD for PR; Standard 3, tailoring the PR programme to patient needs and the local setting; Standard 4, to evaluate the effectiveness of PR; and Standard 5, to conduct education and counselling. Standard 6 addresses public health aspects of PTLD and outcomes due to PR.CONCLUSION: This is the first consensus-based set of Clinical Standards for PTLD. Our aim is to improve patient care and quality of life by guiding clinicians, programme managers and public health officers in planning and implementing adequate measures to assess and manage PTLD.

Prevalence and Population Attributable Risk for Chronic Airflow Obstruction in a Large Multinational Study

Rationale: The Global Burden of Disease programme identified smoking, and ambient and household air pollution as the main drivers of death and disability from Chronic Obstructive Pulmonary Disease (COPD). Objective: To estimate the attributable risk of chronic airflow obstruction (CAO), a quantifiable characteristic of COPD, due to several risk factors. Methods: The Burden of Obstructive Lung Disease study is a cross-sectional study of adults, aged≥40, in a globally distributed sample of 41 urban and rural sites. Based on data from 28,459 participants, we estimated the prevalence of CAO, defined as a post-bronchodilator one-second forced expiratory volume to forced vital capacity ratio < lower limit of normal, and the relative risks associated with different risk factors. Local RR were estimated using a Bayesian hierarchical model borrowing information from across sites. From these RR and the prevalence of risk factors, we estimated local Population Attributable Risks (PAR). Measurements and Main Results: Mean prevalence of CAO was 11.2% in men and 8.6% in women. Mean PAR for smoking was 5.1% in men and 2.2% in women. The next most influential risk factors were poor education levels, working in a dusty job for ≥10 years, low body mass index (BMI), and a history of tuberculosis. The risk of CAO attributable to the different risk factors varied across sites. Conclusions: While smoking remains the most important risk factor for CAO, in some areas poor education, low BMI and passive smoking are of greater importance. Dusty occupations and tuberculosis are important risk factors at some sites.

Influence of KRAS mutations, persistent organic pollutants, and trace elements on survival from pancreatic ductal adenocarcinoma

INTRODUCTION

Reasons why pancreatic ductal adenocarcinoma (PDAC) continues to have poor survival are only partly known. No previous studies have analyzed the combined influence of KRAS mutations, persistent organic pollutants (POPs), and trace elements upon survival in PDAC or in any other human cancer.

OBJECTIVE

To analyze the individual and combined influence of KRAS mutations, POPs, and trace elements upon survival from PDAC.

METHODS

Incident cases of PDAC (n = 185) were prospectively identified in five hospitals in Eastern Spain in 1992-1995 and interviewed face-to-face during hospital admission. KRAS mutational status was determined from tumour tissue through polymerase chain reaction and artificial restriction fragment length polymorphism. Blood and toenail samples were obtained before treatment. Serum concentrations of POPs were analyzed by high-resolution gas chromatography with electron-capture detection. Concentrations of 12 trace elements were determined in toenail samples by inductively coupled plasma mass spectrometry. Multivariable Cox proportional hazards regression was used to assess prognostic associations.

RESULTS

Patients with a KRAS mutated tumor had a 70% higher risk of early death than patients with a KRAS wild-type PDAC (hazard ratio [HR] = 1.7, p = 0.026), adjusting for age, sex, and tumor stage. KRAS mutational status was only modestly and not statistically significantly associated with survival when further adjusting by treatment or by treatment intention. The beneficial effects of treatment remained unaltered when KRAS mutational status was taken into account, and treatment did not appear to be less effective in the subgroup of patients with a KRAS mutated tumor. POPs did not materially influence survival: the adjusted HR of the highest POP tertiles was near unity for all POPs. When considering the joint effect on survival of POPs and KRAS, patients with KRAS mutated tumors had modest and nonsignificant HRs (most HRs around 1.3 to 1.4). Higher concentrations of lead, cadmium, arsenic, vanadium, and aluminium were associated with better survival. When KRAS status, POPs, and trace elements were simultaneously considered along with treatment, only the latter was statistically significantly related to survival.

CONCLUSIONS

In this study based on molecular, clinical, and environmental epidemiology, KRAS mutational status, POPs, and trace elements were not adversely related to PDAC survival when treatment was simultaneously considered; only treatment was independently related to survival. The lack of adverse prognostic effects of POPs and metals measured at the time of diagnosis provide scientific and clinical reassurance on the effects of such exposures upon survival of patients with PDAC. The weak association with KRAS mutations contributes to the scant knowledge on the clinical implications of a genetic alteration highly frequent in PDAC.

Post-tuberculosis lung health: perspectives from the First International Symposium

ALTHOUGH CURABLE, TB frequently leaves the individual with chronic physical and psycho-social impairment, but these consequences have been largely neglected. The 1^st International Post-Tuberculosis Symposium (Stellenbosch, South Africa) was held to discuss priorities and gaps in addressing this issue. A barrier to progress has been the varied terminology and nomenclature, so the Delphi process was used to achieve consensus on definitions. Lack of sufficient evidence hampered definitive recommendations in most domains, including prevention and treatment of post-TB lung disease (PTLD), but the discussions clarified the research needed. A consensus was reached on a toolkit for future PTLD measurement and on PTLD patterns to be considered. The importance of extra-pulmonary consequences and progressive impairment throughout the life-course was identified, including TB recurrence and increased mortality. Patient advocates emphasised the need to address the psychological and social impacts post TB and called for clinical guidance. More generally, there is an urgent need for increased awareness and research into post-TB complications.

Role of DNA methylation in the association of lung function with body mass index: a two-step epigenetic Mendelian randomisation study

BACKGROUND

Low lung function has been associated with increased body mass index (BMI). The aim of this study was to investigate whether the effect of BMI on lung function is mediated by DNA methylation.

METHODS

We used individual data from 285,495 participants in four population-based cohorts: the European Community Respiratory Health Survey, the Northern Finland Birth Cohort 1966, the Swiss Study on Air Pollution and Lung Disease in Adults, and the UK Biobank. We carried out Mendelian randomisation (MR) analyses in two steps using a two-sample approach with SNPs as instrumental variables (IVs) in each step. In step 1 MR, we estimated the causal effect of BMI on peripheral blood DNA methylation (measured at genome-wide level) using 95 BMI-associated SNPs as IVs. In step 2 MR, we estimated the causal effect of DNA methylation on FEV1, FVC, and FEV1/FVC using two SNPs acting as methQTLs occurring close (in cis) to CpGs identified in the first step. These analyses were conducted after exclusion of weak IVs (F statistic < 10) and MR estimates were derived using the Wald ratio, with standard error from the delta method. Individuals whose data were used in step 1 were not included in step 2.

RESULTS

In step 1, we found that BMI might have a small causal effect on DNA methylation levels (less than 1% change in methylation per 1 kg/m2 increase in BMI) at two CpGs (cg09046979 and cg12580248). In step 2, we found no evidence of a causal effect of DNA methylation at cg09046979 on lung function. We could not estimate the causal effect of DNA methylation at cg12580248 on lung function as we could not find publicly available data on the association of this CpG with SNPs.

CONCLUSIONS

To our knowledge, this is the first paper to report the use of a two-step MR approach to assess the role of DNA methylation in mediating the effect of a non-genetic factor on lung function. Our findings do not support a mediating effect of DNA methylation in the association of lung function with BMI.

ERS International Congress, Madrid, 2019: highlights from the Epidemiology and Environment Assembly

At the European Respiratory Society's International Congress of 2019, which was held in Madrid, Spain, there were several sessions with exciting poster and oral presentations within the fields of epidemiology and tobacco control. This article is the summary of two of these sessions. One was on the use of Big Data in epidemiology and the other, on the global burden of respiratory disease and tobacco.

Highlights from the Epidemiology and Environment Assembly at the #ERSCongress 2019http://bit.ly/38p6jEZ

Toenail concentrations of trace elements and occupational history in pancreatic cancer

BACKGROUND

Some occupations potentially entailing exposure to cadmium, arsenic, lead, selenium, nickel, and chromium have been associated with an increased risk of exocrine pancreatic cancer (EPC), but no studies have assessed whether body concentrations of such compounds differed among subjects occupationally exposed and unexposed. No studies which found that exposure to such metals increased the risk of EPC assessed whether past occupations were the source of exposure.

OBJECTIVE

The aim was to analyse the relationship between toenail concentrations of trace elements and occupational history in EPC patients.

METHODS

The study included 114 EPC cases personally interviewed on occupational history and lifestyle factors. Occupations were coded according to the International Standard Classification of Occupations 1988. Selected occupational exposures were assessed by two industrial hygienists and with the Finnish job-exposure matrix (Finjem). Concentrations of 12 trace elements were determined in toenail samples by inductively coupled plasma mass spectrometry. Adjusted geometric means (aGMs) and 95% confidence intervals (95% CI) were calculated.

RESULTS

Patients occupationally exposed to aromatic hydrocarbon solvents (AHs) had higher concentrations of cadmium, manganese, lead, iron and vanadium. The aGM of cadmium concentrations for cases exposed to any pesticide was 0.056 μg/g [95% CI: 0.029-0.108], and, for unexposed cases, 0.023 μg/g [0.017-0.031]. Patients occupationally exposed to pesticides had higher concentrations of cadmium and manganese. Higher concentrations of vanadium, lead and arsenic were related to exposure to formaldehyde. Vanadium and lead were also associated with exposure to chlorinated hydrocarbon solvents, and arsenic was related to exposure to polycyclic aromatic hydrocarbons (PAHs).

CONCLUSIONS

Patients occupationally exposed to AHs, pesticides, chlorinated hydrocarbon solvents, formaldehyde, volatile sulphur compounds and PAHs had higher concentrations of several metals. These elements may account for some of the occupational risks previously reported for pancreatic cancer.

DNA Methylation in Inflammatory Pathways Modifies the Association between BMI and Adult-Onset Non-Atopic Asthma

A high body mass (BMI) index has repeatedly been associated with non-atopic asthma, but the biological mechanism linking obesity to asthma is still poorly understood. We aimed to test the hypothesis that inflammation and/or innate immunity plays a role in the obesity-asthma link. DNA methylome was measured in blood samples of 61 non-atopic participants with asthma and 146 non-atopic participants without asthma (non-smokers for at least 10 years) taking part in the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA) study. Modification by DNA methylation of the association of BMI or BMI change over 10 years with adult-onset asthma was examined at each CpG site and differentially methylated region. Pathway enrichment tests were conducted for genes in a priori curated inflammatory pathways and the NLRP3-IL1B-IL17 axis. The latter was chosen on the basis of previous work in mice. Inflammatory pathways including glucocorticoid/PPAR signaling (p = 0.0023), MAPK signaling (p = 0.013), NF-κB signaling (p = 0.031), and PI3K/AKT signaling (p = 0.031) were enriched for the effect modification of BMI, while NLRP3-IL1B-IL17 axis was enriched for the effect modification of BMI change over 10 years (p = 0.046). DNA methylation measured in peripheral blood is consistent with inflammation as a link between BMI and adult-onset asthma and with the NLRP3-IL1B-IL17 axis as a link between BMI change over 10 years and adult-onset asthma in non-atopic participants.

Airflow Obstruction and Use of Solid Fuels for Cooking or Heating: BOLD Results

RATIONALE

Evidence supporting the association of COPD or airflow obstruction with use of solid fuels is conflicting and inconsistent.

OBJECTIVE

To assess the association of airflow obstruction with self-reported use of solid fuels for cooking or heating.

METHODS

We analysed 18,554 adults from the BOLD study, who had provided acceptable post-bronchodilator spirometry measurements and information on use of solid fuels. The association of airflow obstruction with use of solid fuels for cooking or heating was assessed by sex, within each site, using regression analysis. Estimates were stratified by national income and meta-analysed. We carried out similar analyses for spirometric restriction, chronic cough and chronic phlegm.

MEASUREMENTS AND MAIN RESULTS

We found no association between airflow obstruction and use of solid fuels for cooking or heating (ORmen=1.20, 95%CI 0.94-1.53; ORwomen=0.88, 95%CI 0.67-1.15). This was true for low/middle and high income sites. Among never smokers there was also no evidence of an association of airflow obstruction with use of solid fuels (ORmen=1.00, 95%CI 0.57-1.76; ORwomen=1.00, 95%CI 0.76-1.32). Overall, we found no association of spirometric restriction, chronic cough or chronic phlegm with the use of solid fuels. However, we found that chronic phlegm was more likely to be reported among female never smokers and those who had been exposed for ≥20 years.

CONCLUSION

Airflow obstruction assessed from post-bronchodilator spirometry was not associated with use of solid fuels for cooking or heating.

Female Smokers Are at Greater Risk of Airflow Obstruction Than Male Smokers. UK Biobank

RATIONALE

The prevalence of chronic obstructive pulmonary disease (COPD) is increasing faster among women than among men.

OBJECTIVES

To examine sex differences in the risk of airflow obstruction (a COPD hallmark) in relation to smoking history.

METHODS

We analyzed 149,075 women and 100,252 men taking part in the UK Biobank who had provided spirometry measurements and information on smoking. The association of airflow obstruction with smoking characteristics was assessed by sex using regression analysis. The shape of this relationship was examined using restricted cubic splines.

MEASUREMENTS AND MAIN RESULTS

The association of airflow obstruction with smoking status was stronger in women (odds ratio for ex-smokers [OR_ex], 1.44; OR_current, 3.45) than in men (OR_ex, 1.25; OR_current, 3.06) (P for interaction = 5.6 × 10^-4). In both sexes, the association of airflow obstruction with cigarettes per day, smoking duration, and pack-years did not follow a linear pattern, with the increase in risk at lower doses being steeper among women. For equal doses of exposure, sex differences were present in both ex-smokers and current smokers for cigarettes per day (P for interaction_ex = 6.0 × 10^-8; P for interaction_current = 1.1 × 10^-5), smoking duration (P for interaction_ex = 7.9 × 10^-4; P for interaction_current = 0.004), and pack-years (P for interaction_ex = 6.6 × 10^-18; P for interaction_current = 1.3 × 10^-6). Overall, those who started smoking before age 18 years were more likely to have airflow obstruction, but a sex difference in this association was not clear. For equal time since quitting, the reduction in risk among women seemed less marked than among men.

CONCLUSIONS

Exposed to the same dose of smoking, women showed a higher risk of airflow obstruction than men. This could partly explain the increasingly smaller sex difference in the prevalence of COPD, especially in countries where smoking patterns have become similar between women and men.

Systematic review of lung function and COPD with peripheral blood DNA methylation in population based studies

BACKGROUND

Epigenetic variations in peripheral blood have potential as biomarkers for disease. This systematic review assesses the association of lung function and chronic obstructive pulmonary disease (COPD) with DNA methylation profiles in peripheral blood from population-based studies.

METHODS

Online databases Medline, Embase, and Web of Science were searched. Google Scholar was searched to identify grey literature. After removing duplicate articles, 1155 articles were independently screened by two investigators. Peer reviewed reports on population-based studies that examined peripheral blood DNA methylation in participants with measured lung function (FEV1, FEV1/FVC ratio) or known COPD status were selected for full-text review. Six articles were suitable for inclusion. Information regarding study characteristics, designs, methodologies and conclusions was extracted. A narrative synthesis was performed based on published results.

RESULTS

Three of the six articles assessed the association of COPD with DNA methylation, and two of these also included associations with lung function. Overall, five reports examined the association of lung function with DNA methylation profiles. Five of the six articles reported 'significant' results. However, no consistent CpG sites were identified across studies for COPD status or lung function values.

CONCLUSIONS

DNA methylation patterns in peripheral blood from individuals with reduced lung function or COPD may be different to those in people with normal lung function. However, this systematic review did not find any consistent associations of lung function or COPD with differentially methylated CpG sites. Large studies with a longitudinal design to address reverse causality may prove a more fruitful area of research.

TRIAL REGISTRATION

PROSPERO 2016: CRD42016037352 .

Association of Forced Vital Capacity with the Developmental Gene NCOR2

Background

Forced Vital Capacity (FVC) is an important predictor of all-cause mortality in the absence of chronic respiratory conditions. Epidemiological evidence highlights the role of early life factors on adult FVC, pointing to environmental exposures and genes affecting lung development as risk factors for low FVC later in life. Although highly heritable, a small number of genes have been found associated with FVC, and we aimed at identifying further genetic variants by focusing on lung development genes.

Methods

Per-allele effects of 24,728 SNPs in 403 genes involved in lung development were tested in 7,749 adults from three studies (NFBC1966, ECRHS, EGEA). The most significant SNP for the top 25 genes was followed-up in 46,103 adults (CHARGE and SpiroMeta consortia) and 5,062 children (ALSPAC). Associations were considered replicated if the replication p-value survived Bonferroni correction (p<0.002; 0.05/25), with a nominal p-value considered as suggestive evidence. For SNPs with evidence of replication, effects on the expression levels of nearby genes in lung tissue were tested in 1,111 lung samples (Lung eQTL consortium), with further functional investigation performed using public epigenomic profiling data (ENCODE).

Results

NCOR2-rs12708369 showed strong replication in children (p = 0.0002), with replication unavailable in adults due to low imputation quality. This intronic variant is in a strong transcriptional enhancer element in lung fibroblasts, but its eQTL effects could not be tested due to low imputation quality in the eQTL dataset. SERPINE2-rs6754561 replicated at nominal level in both adults (p = 0.036) and children (p = 0.045), while WNT16-rs2707469 replicated at nominal level only in adults (p = 0.026). The eQTL analyses showed association of WNT16-rs2707469 with expression levels of the nearby gene CPED1. We found no statistically significant eQTL effects for SERPINE2-rs6754561.

Conclusions

We have identified a new gene, NCOR2, in the retinoic acid signalling pathway pointing to a role of vitamin A metabolism in the regulation of FVC. Our findings also support SERPINE2, a COPD gene with weak previous evidence of association with FVC, and suggest WNT16 as a further promising candidate.

Changes in IgE sensitization and total IgE levels over 20 years of follow-up

Background

Cross-sectional studies have reported a lower prevalence of sensitization in older adults, but few longitudinal studies have examined whether this is an aging or a year-of-birth cohort effect.

Objective

We sought to assess changes in sensitization and total IgE levels in a cohort of European adults as they aged over a 20-year period.

Methods

Levels of serum specific IgE to common aeroallergens (house dust mite, cat, and grass) and total IgE levels were measured in 3206 adults from 25 centers in the European Community Respiratory Health Survey on 3 occasions over 20 years. Changes in sensitization and total IgE levels were analyzed by using regression analysis corrected for potential differences in laboratory equipment and by using inverse sampling probability weights to account for nonresponse.

Results

Over the 20-year follow-up, the prevalence of sensitization to at least 1 of the 3 allergens decreased from 29.4% to 24.8% (−4.6%; 95% CI, −7.0% to −2.1%). The prevalence of sensitization to house dust mite (−4.3%; 95% CI, −6.0% to −2.6%) and cat (−2.1%; 95% CI, −3.6% to −0.7%) decreased more than sensitization to grass (−0.6%; 95% CI, −2.5% to 1.3%). Age-specific prevalence of sensitization to house dust mite and cat did not differ between year-of-birth cohorts, but sensitization to grass was most prevalent in the most recent ones. Overall, total IgE levels decreased significantly (geometric mean ratio, 0.63; 95% CI, 0.58-0.68) at all ages in all year-of-birth cohorts.

Conclusion

Aging was associated with lower levels of sensitization, especially to house dust mite and cat, after the age of 20 years.

LINE-1 methylation in granulocyte DNA and trihalomethane exposure is associated with bladder cancer risk

DNA methylation changes contribute to bladder carcinogenesis. Trihalomethanes (THM), a class of disinfection by-products, are associated with increased urothelial bladder cancer (UBC) risk. THM exposure in animal models produces DNA hypomethylation. We evaluated the relationship of LINE-1 5-methylcytosine levels (LINE-1%5mC) as outcome of long-term THM exposure among controls and as an effect modifier in the association between THM exposure and UBC risk. We used a case-control study of UBC conducted in Spain. We obtained personal lifetime residential THM levels and measured LINE-1%5mC by pyrosequencing in granulocyte DNA from blood samples in 548 incident cases and 559 hospital controls. Two LINE-1%5mC clusters (above and below 64%) were identified through unsupervised hierarchical cluster analysis. The association between THM levels and LINE-1%5mC was evaluated with β regression analyses and logistic regression was used to estimate odds ratios (OR) adjusting for covariables. LINE-1%5mC change between percentiles 75(th) and 25(th) of THM levels was 1.8% (95% confidence interval (CI): 0.1, 3.4%) among controls. THM levels above vs. below the median (26 μg/L) were associated with increased UBC risk, OR = 1.86 (95% CI: 1.25, 2.75), overall and among subjects with low levels of LINE-1%5mC (n = 975), OR = 2.14 (95% CI: 1.39, 3.30), but not associated with UBC risk among subjects' high levels of LINE-1%5mC (n = 162), interaction P = 0.03. Results suggest a positive association between LINE-1%5mC and THM levels among controls, and LINE-1%5mC status may modify the association between UBC risk and THM exposure. Because reverse causation and chance cannot be ruled out, confirmation studies are warranted.

Tuberculosis associates with both airflow obstruction and low lung function: BOLD results

In small studies and cases series, a history of tuberculosis has been associated with both airflow obstruction, which is characteristic of chronic obstructive pulmonary disease, and restrictive patterns on spirometry. The objective of the present study was to assess the association between a history of tuberculosis and airflow obstruction and spirometric abnormalities in adults.The study was performed in adults, aged 40 years and above, who took part in the multicentre, cross-sectional, general population-based Burden of Obstructive Lung Disease study, and had provided acceptable post-bronchodilator spirometry measurements and information on a history of tuberculosis. The associations between a history of tuberculosis and airflow obstruction and spirometric restriction were assessed within each participating centre, and estimates combined using meta-analysis. These estimates were stratified by high- and low/middle-income countries, according to gross national income.A self-reported history of tuberculosis was associated with airflow obstruction (adjusted odds ratio 2.51, 95% CI 1.83-3.42) and spirometric restriction (adjusted odds ratio 2.13, 95% CI 1.42-3.19).A history of tuberculosis was associated with both airflow obstruction and spirometric restriction, and should be considered as a potentially important cause of obstructive disease and low lung function, particularly where tuberculosis is common.

Interaction between gas cooking and GSTM1 null genotype in bronchial responsiveness: results from the European Community Respiratory Health Survey

Background

Increased bronchial responsiveness is characteristic of asthma. Gas cooking, which is a major indoor source of the highly oxidant nitrogen dioxide, has been associated with respiratory symptoms and reduced lung function. However, little is known about the effect of gas cooking on bronchial responsiveness and on how this relationship may be modified by variants in the genes GSTM1, GSTT1 and GSTP1, which influence antioxidant defences.

Methods

The study was performed in subjects with forced expiratory volume in one second at least 70% of predicted who took part in the multicentre European Community Respiratory Health Survey, had bronchial responsiveness assessed by methacholine challenge and had been genotyped for GSTM1, GSTT1 and GSTP1-rs1695. Information on the use of gas for cooking was obtained from interviewer-led questionnaires. Effect modification by genotype on the association between the use of gas for cooking and bronchial responsiveness was assessed within each participating country, and estimates combined using meta-analysis.

Results

Overall, gas cooking, as compared with cooking with electricity, was not associated with bronchial responsiveness (β=−0.08, 95% CI −0.40 to 0.25, p=0.648). However, GSTM1 significantly modified this effect (β for interaction=−0.75, 95% CI −1.16 to −0.33, p=4×10⁻⁴), with GSTM1 null subjects showing more responsiveness if they cooked with gas. No effect modification by GSTT1 or GSTP1-rs1695 genotypes was observed.

Conclusions

Increased bronchial responsiveness was associated with gas cooking among subjects with the GSTM1 null genotype. This may reflect the oxidant effects on the bronchi of exposure to nitrogen dioxide.

Genetic and non-genetic predictors of LINE-1 methylation in leukocyte DNA

BACKGROUND

Altered DNA methylation has been associated with various diseases.

OBJECTIVE

We evaluated the association between levels of methylation in leukocyte DNA at long interspersed nuclear element 1 (LINE-1) and genetic and non-genetic characteristics of 892 control participants from the Spanish Bladder Cancer/EPICURO study.

METHODS

We determined LINE-1 methylation levels by pyrosequencing. Individual data included demographics, smoking status, nutrient intake, toenail concentrations of 12 trace elements, xenobiotic metabolism gene variants, and 515 polymorphisms among 24 genes in the one-carbon metabolism pathway. To assess the association between LINE-1 methylation levels (percentage of methylated cytosines) and potential determinants, we estimated beta coefficients (βs) by robust linear regression.

RESULTS

Women had lower levels of LINE-1 methylation than men (β = -0.7, p = 0.02). Persons who smoked blond tobacco showed lower methylation than nonsmokers (β = -0.7, p = 0.03). Arsenic toenail concentration was inversely associated with LINE-1 methylation (β = -3.6, p = 0.003). By contrast, iron (β = 0.002, p = 0.009) and nickel (β = 0.02, p = 0.004) were positively associated with LINE-1 methylation. Single nucleotide polymorphisms (SNPs) in DNMT3A (rs7581217-per allele, β = 0.3, p = 0.002), TCN2 (rs9606756-GG, β = 1.9, p = 0.008; rs4820887-AA, β = 4.0, p = 4.8 × 10-7; rs9621049-TT, β = 4.2, p = 4.7 × 10-9), AS3MT (rs7085104-GG, β = 0.7, p = 0.001), SLC19A1 (rs914238, TC vs. TT: β = 0.5 and CC vs. TT: β = -0.3, global p = 0.0007) and MTHFS (rs1380642, CT vs. CC: β = 0.3 and TT vs. CC; β = -0.8, global p = 0.05) were associated with LINE-1 methylation.

CONCLUSIONS

We identified several characteristics, environmental factors, and common genetic variants that predicted DNA methylation among study participants.

Pancreatic cancer risk and levels of trace elements

BACKGROUND AND AIMS

Knowledge on the aetiology of exocrine pancreatic cancer (EPC) is scant. The best established risk factor for EPC is tobacco smoking. Among other carcinogens, tobacco contains cadmium, a metal previously associated with an increased risk of EPC. This study evaluated the association between concentrations of trace elements in toenails and EPC risk.

METHODS

The study included 118 EPC cases and 399 hospital controls from eastern Spain. Levels of 12 trace elements were determined in toenail samples by inductively coupled plasma mass spectrometry. OR and 95% CI, adjusted for potential confounders, were calculated using logistic regression.

RESULTS

Significantly increased risks of EPC were observed among subjects whose concentrations of cadmium (OR 3.58, 95% CI 1.86 to 6.88; p(trend)=5×10(-6)), arsenic (OR 2.02, 95% CI 1.08 to 3.78; p(trend)=0.009) and lead (OR 6.26, 95% CI 2.71 to 14.47; p(trend)=3×10(-5)) were in the highest quartile. High concentrations of selenium (OR 0.05, 95% CI 0.02 to 0.15; p(trend)=8×10(-11)) and nickel (OR 0.27, 95% CI 0.12 to 0.59; p(trend)=2×10(-4)) were inversely associated with the risk of EPC.

CONCLUSION

Novel associations are reported of lead, nickel and selenium toenail concentrations with pancreas cancer risk. Furthermore, the results confirm previous associations with cadmium and arsenic. These novel findings, if replicated in independent studies, would point to an important role of trace elements in pancreatic carcinogenesis.

Plasma 25-hydroxyvitamin D(3) and bladder cancer risk according to tumor stage and FGFR3 status: a mechanism-based epidemiological study

BACKGROUND

Previous evidence suggests that 25-hydroxyvitamin D(3) [25(OH)D(3)] protects against several cancers. However, little is known regarding urothelial bladder cancer (UBC). We analyzed the association between plasma 25(OH)D(3) and overall risk of UBC, as well as according to stage and FGFR3 molecular subphenotypes.

METHODS

Plasma concentrations of 25(OH)D(3) in 1125 cases with UBC and 1028 control subjects were determined by a chemiluminescence immunoassay. FGFR3 mutational status and expression in tumor tissue were assessed. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression adjusting for potential confounders. Analyses were further stratified by tumor invasiveness and grade, FGFR3 expression, and smoking status. Cell proliferation was measured in human UBC cell lines cultured with 1α,25-dihydroxyvitamin D(3).

RESULTS

A statistically significantly increased risk of UBC was observed among subjects presenting the lowest concentrations of 25(OH)D(3) (OR(adj) = 1.83; 95% CI = 1.19 to 2.82; P = .006), showing a dose-response effect (P (trend) = .004). The association was stronger for patients with muscle-invasive tumors, especially among low-FGFR3 expressers (OR(adj) = 5.94; 95% CI = 1.72 to 20.45; P = .005). The biological plausibility of these associations is supported by the fact that, in vitro, 1α,25-dihydroxyvitamin D(3) upregulates FGFR3 expression in UBC cell lines with low levels of wild-type FGFR3.

CONCLUSION

These findings support a role of vitamin D in the pathogenesis of UBC and show that 25(OH)D(3) levels are associated with FGFR3 expression in the tumor. Because FGFR3 mutation and overexpression are markers of better outcome, our findings suggest that individuals with low levels of plasma 25(OH)D(3) may be at high risk of more aggressive forms of UBC.

Cyclooxygenase-2 expression in bladder cancer and patient prognosis: results from a large clinical cohort and meta-analysis

Aberrant overexpression of cyclooxygenase-2 (COX2) is observed in urothelial carcinoma of the bladder (UCB). Studies evaluating COX2 as a prognostic marker in UCB report contradictory results. We determined the prognostic potential of COX2 expression in UCB and quantitatively summarize the results with those of the literature through a meta-analysis. Newly diagnosed UCB patients recruited between 1998–2001 in 18 Spanish hospitals were prospectively included in the study and followed-up (median, 70.7 months). Diagnostic slides were reviewed and uniformly classified by expert pathologists. Clinical data was retrieved from hospital charts. Tissue microarrays containing non-muscle invasive (n = 557) and muscle invasive (n = 216) tumours were analyzed by immunohistochemistry using quantitative image analysis. Expression was evaluated in Cox regression models to assess the risk of recurrence, progression and disease-specific mortality. Meta-hazard ratios were estimated using our results and those from 11 additional evaluable studies. COX2 expression was observed in 38% (211/557) of non-muscle invasive and 63% (137/216) of muscle invasive tumors. Expression was associated with advanced pathological stage and grade (p<0.0001). In the univariable analyses, COX2 expression - as a categorical variable - was not associated with any of the outcomes analyzed. As a continuous variable, a weak association with recurrence in non-muscle invasive tumors was observed (p-value = 0.048). In the multivariable analyses, COX2 expression did not independently predict any of the considered outcomes. The meta-analysis confirmed these results. We did not find evidence that COX2 expression is an independent prognostic marker of recurrence, progression or survival in patients with UCB.

Selenium and bladder cancer risk: a meta-analysis

BACKGROUND

Selenium is considered to be an antioxidant, and its high levels have been inversely associated with cancer risk of several sites. This meta-analysis examined the relationship between levels of selenium measured in serum and toenails, and the risk of bladder cancer.

METHODS

A meta-analysis using data from seven published epidemiologic studies (three case-control, three nested case-control, one case-cohort) published before March 2010 was done to examine the association between levels of selenium and bladder cancer. Fixed and random effects analyses were done to calculate meta-odds ratio (mOR) and 95% confidence intervals (CI). Heterogeneity among studies was measured by the I(2) statistic.

RESULTS

Overall, the risk of bladder cancer was inversely associated with elevated levels of selenium according to a random-effects model (mOR = 0.61; 95% CI, 0.42-0.87). The mORs were 0.95 (95% CI, 0.69-1.27) and 0.55 (95% CI, 0.32-0.95) among men and women, respectively. Sex, type of sample specimen, smoking status, and study design were found to be potential sources of heterogeneity.

CONCLUSIONS

A significant protective effect of selenium, observed mainly among women, may result from gender-specific differences in its accumulation and excretion. The heterogeneity found among studies was mainly linked to the different biological sample specimens used to measure the selenium concentrations and the small size of the studies. Although these results suggest a protective effect of selenium for bladder cancer risk, additional large studies are warranted to support these preliminary evidence.

IMPACT

The present results suggest a beneficial effect of high selenium intake for bladder cancer risk.

Trace metals and over-expression of metallothioneins in bladder tumoral lesions: a case-control study

BACKGROUND

Previous studies have provided some evidence of a possible association between cancer and metallothioneins. Whether this relates to an exposure to carcinogenic metals remains unclear.

METHODS

In order to examine the association between the expression of metallothioneins and bladder tumors, and to compare the levels of arsenic, cadmium, chromium, lead and nickel in animals with bladder tumors and animals without bladder tumors, 37 cases of bovine bladder tumors and 17 controls were collected. The detection and quantification of metallothioneins in bladder tissue of both cases and controls was performed by immunohistochemistry. And the quantification of metals in tissue and hair was assessed by inductively coupled plasma - mass spectrometry.

RESULTS

Increased expression of metallothioneins was associated with bladder tumors when compared with non-tumoral bladder tissue (OR = 9.3, 95% CI: 1.0 - 480). The concentrations of cadmium, chromium, lead and nickel in hair of cases were significantly higher than those of controls. However, as for the concentration of metals in bladder tissue, the differences were not significant.

CONCLUSION

Though the sample size was small, the present study shows an association between bladder tumors and metallothioneins. Moreover, it shows that concentrations of metals such as cadmium, chromium, lead and nickel in hair may be used as a biomarker of exposure.

Prevalence of Calodium hepaticum (Syn. Capillaria hepatica) in house mice (Mus musculus) in the Azores archipelago

Calodium hepaticum (Syn. Capillaria hepatica) is a zoonotic liver nematode of mammals distributed worldwide. Rodents are believed to be the main reservoirs of this nematode. In this paper, prevalence of the parasite was analyzed in liver histological sections from 51 house mice (Mus musculus) caught in human-inhabited houses, from two localities (Furnas and Rabo de Peixe) on São Miguel island from the Azores archipelago (Portugal). Mean prevalence of infection was 19.6%, with 33.3% prevalence in Furnas and 4.1% in Rabo de Peixe (P=0.07). No significant differences were found between the prevalence of infection and the age, body weight and the sex of mice. Hepatic lesions found were either acute and/or chronic stage and consisted of moderate to severe multifocal pyogranulomatous hepatitis with encapsulated eggs with typical bipolar plugs and moderate to severe necrotizing hepatitis consistent with larva tracks. Periportal inflammatory infiltration, hepatocyte regeneration and bile duct hyperplasia were also noted. In most cases, hepatic lesions occupied more than 50% of the liver, but despite severe lesions, in some mice, no signs of hepatic failure were noticed. The high rate of infection found in the present study suggests that house mice are an important reservoir for this parasite in the Azores and could have a role in human transmission.

Essential and non-essential trace metals in scalp hair of men chronically exposed to volcanogenic metals in the Azores, Portugal

Volcanoes produce and release large amounts of toxicants, and the concentration of metals in hair can be used as a biomarker of exposure to trace metals. In order to investigate whether humans exposed to volcanic emissions demonstrate higher concentrations of essential and non-essential trace metals, scalp hair of men (3-89 years) living in two areas of the Azores, one exposed to volcanic emissions and the other not, was sampled, and their content in Cd, Cu, Pb, Rb, Se, and Zn was quantified by using High Resolution Inductively Coupled Plasma Mass Spectrometry. In average, men exposed to volcanic emissions presented higher concentrations of Cd (96.9 ppb), Cu (16.2 ppm), Pb (3417.6 ppb), Rb (216.3 ppb), and Zn (242.8 ppm), but not Se (469.6 ppb). Also, strong and significant correlations were found between Cd-Rb and Pb-Rb in the exposed men. In conclusion, humans living chronically exposed to volcanic emissions show high concentrations of essential and non-essential trace metals in scalp hair, and is suggested that this type of exposure may be as harmful as living close to industrial facilities.