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

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.; 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 FEV; 1; , FVC, and FEV; 1; /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.; 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.; 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

SERPINA1 methylation and lung function in tobacco-smoke exposed European children and adults:A meta-analysis of ALEC population-based cohorts

BackgroundThe pathophysiological role of SERPINA1 in respiratory health may be more strongly determined by the regulation of its expression than by common genetic variants. A family based study of predominantly smoking adults found methylation at two Cytosine-phosphate-Guanine sites (CpGs) in SERPINA1 gene to be associated with chronic obstructive pulmonary disease risk. The objective of this study was to confirm the association of lung function with SERPINA1 methylation in general population samples by testing a comprehensive set of CpGs in the SERPINA gene cluster. We considered lung function level and decline in adult smokers from three European population-based cohorts and lung function level and growth in tobacco-smoke exposed children from a birth cohort.MethodsDNA methylation using Illumina Infinium Human Methylation 450 k and EPIC beadchips and lung function were measured at two time points in 1076 SAPALDIA, ECRHS and NFBC adult cohort participants and 259 ALSPAC children. Associations of methylation at 119 CpG sites in the SERPINA gene cluster (PP4R4-SERPINA13P) with lung functions and circulating alpha-1-antitripsin (AAT) were assessed using multivariable cross-sectional and longitudinal regression models.ResultsMethylation at cg08257009 in the SERPINA gene cluster, located 32 kb downstream of SERPINA1, not annotated to a gene, was associated with FEV1/FVC at the Bonferroni corrected level in adults, but not in children. None of the methylation signals in the SERPINA1 gene showed associations with lung function after correcting for multiple testing.ConclusionsThe results do not support a role of SERPINA1 gene methylation as determinant of lung function across the life course in the tobacco smoke exposed general population exposed

Epigenome-wide association study of lung function level and its change

Previous reports link differential DNA methylation (DNAme) to environmental exposures that are associated with lung function. Direct evidence on lung function DNAme is, however, limited. We undertook an agnostic epigenome-wide association study (EWAS) on pre-bronchodilation lung function and its change in adults. In a discovery-replication EWAS design, DNAme in blood and spirometry were measured twice, 6-15 years apart, in the same participants of three adult population-based discovery cohorts (n=2043). Associated DNAme markers (p EWAS signals were enriched for smoking-related DNAme. We replicated 57 lung function DNAme markers in adult, but not childhood samples, all previously associated with smoking. Markers not previously associated with smoking failed replication. cg05575921 (AHRR (aryl hydrocarbon receptor repressor)) showed the statistically most significant association with cross-sectional lung function (FEV1/FVC: pdiscovery=3.96x10(-21) and pcombined=7.22x10(-50)). A score combining 10 DNAme markers previously reported to mediate the effect of smoking on lung function was associated with lung function (FEV1/FVC: p=2.65x10(-20)). Our results reveal that lung function-associated methylation signals in adults are predominantly smoking related, and possibly of clinical utility in identifying poor lung function and accelerated decline. Larger studies with more repeat time-points are needed to identify lung function DNAme in never-smokers and in children.Peer reviewe

Racial and Ethnic Differences in Endometrial Cancer

Introduction: Endometrial cancer (EC) is the fourth most frequently diagnosed and the most common gynecologic cancer among American women. Past research suggests that racial/ethnic differences in EC outcomes exist; however these differences were almost exclusively examined in non-Hispanic White (NHW) and non-Hispanic Black (NHB) women. Asians and Hispanics represent the fastest growing minority populations in the United States, yet most investigations have failed to include them in their analyses. In addition, previous research has generally presented results for overall EC, although recommended treatment regimens vary by histologic subtype and there is evidence that subtype-specific survival differences exist. The goal of this research was to assess whether racial/ethnic differences in stage at diagnosis, treatment modalities and 5-year overall survival existed and explore what factors mediated these differences. Methods: The purpose of the first aim was to assess racial/ethnic differences in tumor, sociodemographic and treatment facility characteristics for Type 1 - low-grade endometrioid carcinomas (LGEC) and Type 2 EC - high-grade endometrioid carcinomas (HGEC), clear cell carcinomas (CCC) and serous carcinomas (SC). In addition, the goal of this aim was to determine whether subtype-specific racial/ethnic differences in stage at diagnosis between minority women and NHW existed. The main purpose of our second aim was to assess whether subtype-specific racial/ethnic differences existed in receipt of EC treatment, defined as surgery, radiation therapy and chemotherapy. The secondary goal of aim 2 was to assess the relative contribution of hypothesized mediators related to tumor characteristics, socio-economic and treatment facility factors on the detected racial/ethnic differences in receipt of treatment. The final aim was to assess whether subtype-specific racial/ethnic differences in overall five-year EC survival existed and explore whether the relative contribution of hypothesized mediators related to tumor characteristics, socio-economic factors, receipt of treatment and treatment facility factors on the detected differences. Results: In our first aim, we found that compared to NHW women, NHB women are significantly more likely to be diagnosed with aggressive EC subtypes. The results from our second aim showed that NHB women were the only minority group that had higher odds of not receiving surgical treatment than NHW, across all EC subtypes. Moreover, NHPI had five times higher odds of not receiving surgical treatment for SC than NHW. When assessing racial/ethnic differences in the receipt of radiation therapy and chemotherapy, we demonstrated that NHAIAN diagnosed with SC had higher odds of not receiving radiation therapy than NHW. Moreover, NHB women diagnosed with CCC had higher odds and NHA diagnosed with LGEC had lower odds of not receiving chemotherapy than NHW. In addition, the results of the mediation analyses showed that racial/ethnic differences in receipt of surgical treatment in women diagnosed with LGEC, HGEC and SC were partially mediated by the socio-economic (SE) domain. With respect to survival, NHB women diagnosed with LGEC, HGEC and SC had a lower overall 5-year survival than NHW. Additionally, NHA diagnosed with LGEC and Hispanics diagnosed with HGEC had a higher overall 5-year survival than NHW women. Lastly, the results from our mediation analyses demonstrated that receipt of surgical treatment and the SE domain contributed to NHB-NHW differences in overall 5-year survival in women diagnosed with LGEC and HGEC. Discussion: Subtype-specific racial/ethnic differences in stage at diagnosis, receipt of treatment and 5-year overall survival in women diagnosed with EC exist. These differences can be attributed to several factors, including a lack of knowledge about EC symptoms, refusal of surgery by women of lower socio-economic status (SES), and structural and social barriers present in areas of lower SES. Interventions to address the detected disparities could consist of efforts to improve the timeliness of diagnosis by raising the awareness about EC symptoms, to increase knowledge about the necessity of EC surgery in women who are likely to refuse treatment and to assist women of lower SES overcome barriers to accessing health services present in the area they live in. These interventions could be carried out within the framework of a patient navigation project or with the aid of community/social workers

Incidence trends of airflow obstruction among European adults without asthma: a 20-year cohort study

Investigating COPD trends may help healthcare providers to forecast future disease burden. We estimated sex- and smoking-specific incidence trends of pre-bronchodilator airflow obstruction (AO) among adults without asthma from 11 European countries within a 20-year follow-up (ECRHS and SAPALDIA cohorts). We also quantified the extent of misclassification in the definition based on pre-bronchodilator spirometry (using post-bronchodilator measurements from a subsample of subjects) and we used this information to estimate the incidence of post-bronchodilator AO (AOpost-BD), which is the primary characteristic of COPD. AO incidence was 4.4 (95% CI: 3.5-5.3) male and 3.8 (3.1-4.6) female cases/1,000/year. Among ever smokers (median pack-years: 20, males; 12, females), AO incidence significantly increased with ageing in men only [incidence rate ratio (IRR), 1-year increase: 1.05 (1.03-1.07)]. A strong exposure-response relationship with smoking was found both in males [IRR, 1-pack-year increase: 1.03 (1.02-1.04)] and females [1.03 (1.02-1.05)]. The positive predictive value of AO for AOpost-BD was 59.1% (52.0-66.2%) in men and 42.6% (35.1-50.1%) in women. AOpost-BD incidence was 2.6 (1.7-3.4) male and 1.6 (1.0-2.2) female cases/1,000/year. AO incidence was considerable in Europe and the sex-specific ageing-related increase among ever smokers was strongly related to cumulative tobacco exposure. AOpost-BD incidence is expected to be half of AO incidence.ALEC has received funding from the European Union’s Horizon 2020 research and innovation programme [Grant Agreement No. 633212]. The co-ordination of the ECRHS was supported by the European Commission (phases 1 and 2) and the Medical Research Council (phase 3). The SAPALDIA cohort was funded by The State Secretariat for Education, Research and Innovation (SERI), Switzerland. The principal investigators and team members of the ECRHS and SAPALDIA studies, and the national funders who supported data collection in the ECRHS and SAPALDIA studies are listed in the appendix available in the Supplementary Information

Airway responsiveness to methacholine and incidence of COPD: an international prospective cohort study

Background: It has been debated, but not yet established, whether increased airway responsiveness can predict COPD. Recognising this link may help in identifying subjects at risk. Objective: We studied prospectively whether airway responsiveness is associated with the risk of developing COPD. Methods: We pooled data from two multicentre cohort studies that collected data from three time points using similar methods (European Community Respiratory Health Survey and Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults). We classified subjects (median age 37 years, 1st–3rd quartiles: 29–44) by their level of airway responsiveness using quintiles of methacholine dose–response slope at the first examination (1991–1994). Then, we excluded subjects with airflow obstruction at the second examination (1999–2003) and analysed incidence of COPD (postbronchodilator FEV1/FVC below the lower limit of normal) at the third examination (2010–2014) as a function of responsiveness, adjusting for sex, age, education, body mass index, history of asthma, smoking, occupational exposures and indicators of airway calibre. Results: We observed 108 new cases of COPD among 4205 subjects during a median time of 9 years. Compared with the least responsive group (incidence rate 0.6 per 1000/year), adjusted incidence rate ratios for COPD ranged from 1.79 (95% CI 0.52 to 6.13) to 8.91 (95% CI 3.67 to 21.66) for increasing airway responsiveness. Similar dose–response associations were observed between smokers and non-smokers, and stronger associations were found among subjects without a history of asthma or asthma-like symptoms. Conclusions: Our study suggests that increased airway responsiveness is an independent risk factor for COPD. Further research should clarify whether early treatment in patients with high responsiveness can slow down disease progression

Airway responsiveness to methacholine and incidence of COPD: an international prospective cohort study

Background: It has been debated, but not yet established, whether increased airway responsiveness can predict COPD. Recognising this link may help in identifying subjects at risk. Objective: We studied prospectively whether airway responsiveness is associated with the risk of developing COPD. Methods: We pooled data from two multicentre cohort studies that collected data from three time points using similar methods (European Community Respiratory Health Survey and Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults). We classified subjects (median age 37 years, 1st-3rd quartiles: 29-44) by their level of airway responsiveness using quintiles of methacholine dose-response slope at the first examination (1991-1994). Then, we excluded subjects with airflow obstruction at the second examination (1999-2003) and analysed incidence of COPD (postbronchodilator FEV1/FVC below the lower limit of normal) at the third examination (2010-2014) as a function of responsiveness, adjusting for sex, age, education, body mass index, history of asthma, smoking, occupational exposures and indicators of airway calibre. Results: We observed 108 new cases of COPD among 4205 subjects during a median time of 9 years. Compared with the least responsive group (incidence rate 0.6 per 1000/year), adjusted incidence rate ratios for COPD ranged from 1.79 (95% CI 0.52 to 6.13) to 8.91 (95% CI 3.67 to 21.66) for increasing airway responsiveness. Similar dose-response associations were observed between smokers and non-smokers, and stronger associations were found among subjects without a history of asthma or asthma-like symptoms. Conclusions: Our study suggests that increased airway responsiveness is an independent risk factor for COPD. Further research should clarify whether early treatment in patients with high responsiveness can slow down disease progression.The ALEC Study is funded by the European Union’s Horizon 2020 Research and Innovation programme under grant agreement no. 633212. ISGlobal is a member of the CERCA Programme, Generalitat de Catalunya. The SAPALDIA cohort has been funded since 1991 primarily by the Swiss National Science Foundation (grants no 33CS30-148470/1&2, 33CSCO-134276/1, 33CSCO-108796, 324730_135673, 3247BO-104283, 3247BO-104288, 3247BO-104284, 3247-065896, 3100-059302, 3200-052720, 3200-042532, 4026-028099, PMPDP3_129021/1, PMPDP3_141671/1). Other national funders who supported data collection in the original studies are listed in the supplement

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

Abstract 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 &lt; 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