Integrative pathway genomics of lung function and airflow obstruction.

Chronic respiratory disorders are important contributors to the global burden of disease. Genome-wide association studies (GWASs) of lung function measures have identified several trait-associated loci, but explain only a modest portion of the phenotypic variability. We postulated that integrating pathway-based methods with GWASs of pulmonary function and airflow obstruction would identify a broader repertoire of genes and processes influencing these traits. We performed two independent GWASs of lung function and applied gene set enrichment analysis to one of the studies and validated the results using the second GWAS. We identified 131 significantly enriched gene sets associated with lung function and clustered them into larger biological modules involved in diverse processes including development, immunity, cell signaling, proliferation and arachidonic acid. We found that enrichment of gene sets was not driven by GWAS-significant variants or loci, but instead by those with less stringent association P-values. Next, we applied pathway enrichment analysis to a meta-analyzed GWAS of airflow obstruction. We identified several biologic modules that functionally overlapped with those associated with pulmonary function. However, differences were also noted, including enrichment of extracellular matrix (ECM) processes specifically in the airflow obstruction study. Network analysis of the ECM module implicated a candidate gene, matrix metalloproteinase 10 (MMP10), as a putative disease target. We used a knockout mouse model to functionally validate MMP10's role in influencing lung's susceptibility to cigarette smoke-induced emphysema. By integrating pathway analysis with population-based genomics, we unraveled biologic processes underlying pulmonary function traits and identified a candidate gene for obstructive lung disease.

Prothrombotic genetic risk factors are associated with an increased risk of liver fibrosis in the general population: The Rotterdam Study.

BACKGROUND & AIMS: The coagulation system is known to be involved in fibrogenesis in patients with liver disease. We investigated whether common genetic prothrombotic risk factors are associated with an increased risk of fibrosis in the general population. METHODS: This investigation was part of the Rotterdam Study, an ongoing, population-based cohort study. Liver stiffness (LS) was measured using transient elastography (Fibroscan) and associated with single nucleotide polymorphisms determining blood group type and presence of the Factor V Leiden (FVL) mutation or prothrombin G20210A gene variant. RESULTS: Reliable LS measurements and genetic data were obtained from 1055 Caucasian participants. LS ⩾8.0 kPa, suggestive of clinically relevant fibrosis, was observed in 101 subjects (9.6%). Presence of FVL or prothrombin G20210A was independently associated with an increased risk of LS ⩾8.0 kPa (OR 2.09, 95%CI 1.07-4.07, p=0.03). Combination of blood group type non-O and the FVL mutation or prothrombin G20210A variant resulted in an even higher risk of LS ⩾8.0 kPa (OR 3.36, 95%CI 1.50-7.56, p=0.003). Presence of the FVL mutation or prothrombin G20210A variant in participants with blood group non-O was associated with a predicted probability of 14.3% (7.7-23.8) of LS ⩾8.0 kPa. CONCLUSIONS: Participants carrying the FVL mutation or prothrombin G20210A variant have an increased risk of clinically relevant liver fibrosis, which is even higher in blood group type non-O carriers. The fact that genetic prothrombotic risk factors are associated with an increased risk of liver fibrosis suggests that coagulation plays an important role in fibrogenesis in the general population.

Genome-wide joint meta-analysis of SNP and SNP-by-smoking interaction identifies novel loci for pulmonary function.

Genome-wide association studies have identified numerous genetic loci for spirometic measures of pulmonary function, forced expiratory volume in one second (FEV(1)), and its ratio to forced vital capacity (FEV(1)/FVC). Given that cigarette smoking adversely affects pulmonary function, we conducted genome-wide joint meta-analyses (JMA) of single nucleotide polymorphism (SNP) and SNP-by-smoking (ever-smoking or pack-years) associations on FEV(1) and FEV(1)/FVC across 19 studies (total N = 50,047). We identified three novel loci not previously associated with pulmonary function. SNPs in or near DNER (smallest P(JMA = )5.00×10(-11)), HLA-DQB1 and HLA-DQA2 (smallest P(JMA = )4.35×10(-9)), and KCNJ2 and SOX9 (smallest P(JMA = )1.28×10(-8)) were associated with FEV(1)/FVC or FEV(1) in meta-analysis models including SNP main effects, smoking main effects, and SNP-by-smoking (ever-smoking or pack-years) interaction. The HLA region has been widely implicated for autoimmune and lung phenotypes, unlike the other novel loci, which have not been widely implicated. We evaluated DNER, KCNJ2, and SOX9 and found them to be expressed in human lung tissue. DNER and SOX9 further showed evidence of differential expression in human airway epithelium in smokers compared to non-smokers. Our findings demonstrated that joint testing of SNP and SNP-by-environment interaction identified novel loci associated with complex traits that are missed when considering only the genetic main effects.

A genome-wide association study for venous thromboembolism: the extended cohorts for heart and aging research in genomic epidemiology (CHARGE) consortium.

Venous thromboembolism (VTE) is a common, heritable disease resulting in high rates of hospitalization and mortality. Yet few associations between VTE and genetic variants, all in the coagulation pathway, have been established. To identify additional genetic determinants of VTE, we conducted a two-stage genome-wide association study (GWAS) among individuals of European ancestry in the extended cohorts for heart and aging research in genomic epidemiology (CHARGE) VTE consortium. The discovery GWAS comprised 1,618 incident VTE cases out of 44,499 participants from six community-based studies. Genotypes for genome-wide single-nucleotide polymorphisms (SNPs) were imputed to approximately 2.5 million SNPs in HapMap and association with VTE assessed using study-design appropriate regression methods. Meta-analysis of these results identified two known loci, in F5 and ABO. Top 1,047 tag SNPs (P ≤ 0.0016) from the discovery GWAS were tested for association in an additional 3,231 cases and 3,536 controls from three case-control studies. In the combined data from these two stages, additional genome-wide significant associations were observed on 4q35 at F11 (top SNP rs4253399, intronic to F11) and on 4q28 at FGG (rs6536024, 9.7 kb from FGG; P < 5.0 × 10(-13) for both). The associations at the FGG locus were not completely explained by previously reported variants. Loci at or near SUSD1 and OTUD7A showed borderline yet novel associations (P < 5.0 × 10(-6) ) and constitute new candidate genes. In conclusion, this large GWAS replicated key genetic associations in F5 and ABO, and confirmed the importance of F11 and FGG loci for VTE. Future studies are warranted to better characterize the associations with F11 and FGG and to replicate the new candidate associations.

Common genes underlying asthma and COPD? Genome-wide analysis on the Dutch hypothesis.

Asthma and chronic obstructive pulmonary disease (COPD) are thought to share a genetic background ("Dutch hypothesis"). We investigated whether asthma and COPD have common underlying genetic factors, performing genome-wide association studies for both asthma and COPD and combining the results in meta-analyses. Three loci showed potential involvement in both diseases: chr2p24.3, chr5q23.1 and chr13q14.2, containing DDX1, COMMD10 (both participating in the nuclear factor (NF) κß pathway) and GNG5P5, respectively. Single nucleotide polymorphisms (SNPs) rs9534578 in GNG5P5 reached genome-wide significance after first replication phase (p=9.96×10(-9)). The second replication phase, in seven independent cohorts, provided no significant replication. Expression quantitative trait loci (eQTL) analysis in blood cells and lung tissue on the top 20 associated SNPs identified two SNPs in COMMD10 that influenced gene expression. Inflammatory processes differ in asthma and COPD and are mediated by NF-κß, which could be driven by the same underlying genes, COMMD10 and DDX1. None of the SNPs reached genome-wide significance. Our eQTL studies support a functional role for two COMMD10 SNPs, since they influence gene expression in both blood cells and lung tissue. Our findings suggest that there is either no common genetic component in asthma and COPD or, alternatively, different environmental factors, e.g. lifestyle and occupation in different countries and continents, which may have obscured the genetic common contribution.

ß-Adrenoceptor blockers and pulmonary function in the general population: the Rotterdam Study.

AIM: ß-Adrenoceptor blockers have been used with caution in patients with obstructive lung diseases such as asthma or chronic obstructive pulmonary disease (COPD), due to the potentially increased airway reactivity and risk of bronchial obstruction. Cardioselective ß-adrenoceptor blockers have a more beneficial profile than non-cardioselective ß-adrenoceptor blockers and can be safely prescribed to patients with both cardiovascular disease and COPD. We hypothesized that cardioselective ß-adrenoceptor blockers also affect pulmonary function. METHODS: This study was performed within the Rotterdam Study, a prospective population-based cohort study. Effects of cardioselective and non-cardioselective ß-adrenoceptor blockers on pulmonary function were analysed using regression techniques with multivariable adjustment for potential confounders. RESULTS: Current use of non-cardioselective ß-adrenoceptor blockers was significantly associated with a lower forced expiratory volume in 1 s (FEV1) of -198 ml (95% CI -301, -96), with a lower forced vital capacity (FVC) of -223 ml (95% CI -367, -79) and with a decreased FEV1 : FVC of -1.38% (95% CI -2.74, -0.13%). Current use of cardioselective ß-adrenoceptor blockers was significantly associated with a lower FEV1 of -118 ml (95% CI -157, -78) and with a lower FVC of -167 ml (95% CI -222, -111), but did not affect FEV1: FVC. After exclusion of patients with COPD, asthma and heart failure the effects of cardioselective ß-adrenoceptor blockers remained significant for FEV1 (-142 ml [95% CI -189, -96]) and for FVC (-176 ml [95% CI -236, -117]). CONCLUSION: In our study both non-cardioselective and cardioselective ß-adrenoceptor blockers had a clinically relevant effect on both FEV1 and FVC. In contrast to cardioselective ß-adrenoceptor blockers, use of non-cardioselective ß-adrenoceptor blockers was associated with a significantly lower FEV1: FVC.

Adverse outcomes of frailty in the elderly: the Rotterdam Study.

To investigate the prevalence of frailty in a Dutch elderly population and to identify adverse health outcomes associated with the frailty phenotype independent of the comorbidities. Cross-sectional and longitudinal analyses within the Rotterdam Study (the Netherlands), a prospective population-based cohort study in persons aged ≥55 years. Frailty was defined as meeting three or more of five established criteria for frailty, evaluating nutritional status, physical activity, mobility, grip strength and exhaustion. Intermediate frailty was defined as meeting one or two frailty criteria. Comorbidities were objectively measured. Health outcomes were assessed by means of questionnaires, physical examinations and continuous follow-up through general practitioners and municipal health authorities for mortality. Of 2,833 participants (median age 74.0 years, inter quartile range 9) with sufficiently evaluated frailty criteria, 163 (5.8 %) participants were frail and 1,454 (51.3 %) intermediate frail. Frail elderly were more likely to be older and female, to have an impaired quality of life and to have fallen or to have been hospitalized. 108 (72.0 %) frail participants had ≥2 comorbidities, compared to 777 (54.4 %) intermediate frail and 522 (44.8 %) non-frail participants. Adjusted for age, sex and comorbidities, frail elderly had a significantly increased risk of dying within 3 years (HR 3.4; 95 % CI 1.9-6.4), compared to the non-frail elderly. This study in a general Dutch population of community-dwelling elderly able to perform the frailty tests, demonstrates that frailty is common and that frail elderly are at increased risk of death independent of comorbidities.

Chronic obstructive pulmonary disease and cerebral microbleeds. The Rotterdam Study.

RATIONALE: Chronic obstructive pulmonary disease (COPD) is a common, complex multisystem disease in the elderly with multiple comorbidities that significantly impact morbidity and mortality. Although cerebral small-vessel disease is an important cause of cognitive decline and age-related disability, it is a poorly investigated potential systemic manifestation of patients with COPD. OBJECTIVES: To examine whether COPD relates to the development and location of cerebral microbleeds, a novel marker of cerebral small-vessel disease. METHODS: Cross-sectional and longitudinal analyses were part of the Rotterdam Study, a prospective population-based cohort study in subjects aged greater than or equal to 55 years. Diagnosis of COPD was confirmed by spirometry. Cerebral microbleeds were detected using high-resolution magnetic resonance imaging (MRI). MEASUREMENTS AND MAIN RESULTS: Subjects with COPD (n = 165) had a higher prevalence of cerebral microbleeds compared with subjects with normal lung function (n = 645) independent of age, sex, smoking status, atherosclerotic macroangiopathy, antithrombotic use, total cholesterol, triglycerides, and serum creatinin (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.15-2.47; P = 0.007). Regarding the specific microbleed location, subjects with COPD had a significantly higher prevalence of microbleeds in deep or infratentorial locations (OR, 3.3; 95% CI, 1.97-5.53; P < 0.001), which increased with severity of airflow limitation and are suggestive of hypertensive or arteriolosclerotic microangiopathy. Furthermore, in longitudinal analysis restricted to subjects without microbleed at baseline, COPD was an independent predictor of incident cerebral microbleeds in deep or infratentorial locations (OR, 7.1; 95% CI, 2.1-24.5; P = 0.002). CONCLUSIONS: Our findings are compatible with COPD causing an increased risk of the development of cerebral microbleeds in deep or infratentorial locations.

Chronic obstructive pulmonary disease and lipid core carotid artery plaques in the elderly: the Rotterdam Study.

RATIONALE: Chronic obstructive pulmonary disease (COPD) is an independent risk factor for ischemic stroke and the risk increases with severity of airflow limitation. Even though vulnerable carotid artery plaque components, such as intraplaque hemorrhage and lipid core, place persons at high risk for ischemic events, the plaque composition in patients with COPD has never been explored. OBJECTIVES: To investigate the prevalence of carotid wall thickening, the different carotid artery plaque components, and their relationship with severity of airflow limitation in elderly patients with COPD. METHODS: This cross-sectional analysis was part of the Rotterdam Study, a prospective population-based cohort study performed in subjects aged 55 years and older. Diagnosis of COPD was confirmed by spirometry. Participants with carotid wall intima-media thickness greater than or equal to 2.5 mm on ultrasonography underwent high-resolution magnetic resonance imaging for characterization of carotid plaques. Data were analyzed using logistic regression. MEASUREMENTS AND MAIN RESULTS: COPD cases (n = 253) had a twofold increased risk (odds ratio, 2.0; 95% confidence interval, 1.44-2.85; P < 0.0001) of presentation with carotid wall thickening on ultrasonography compared with control subjects with a normal lung function (n = 920). Moreover, the risk increased significantly with severity of airflow limitation. On magnetic resonance imaging, vulnerable lipid core plaques were more frequent in COPD cases than in control subjects (odds ratio, 2.1; 95% confidence interval, 1.25-3.69; P = 0.0058). CONCLUSIONS: Carotid artery wall thickening is more prevalent in patients with COPD than in control subjects. In elderly subjects with carotid wall thickening, COPD is an independent predictor for the presence of a lipid core, and therefore of vulnerable plaques.

Statins, systemic inflammation and risk of death in COPD: the Rotterdam study.

BACKGROUND: Studies suggest that statins decrease mortality in COPD patients but it is unknown which patients might benefit most. OBJECTIVES: We investigated whether statins were associated with reduced mortality in COPD patients and whether effects differed according to baseline high-sensitivity C-reactive protein (hsCRP) concentration, a marker of systemic inflammation. METHODS: This nested case-control study was part of the Rotterdam Study, a prospective population-based cohort study among 7983 subjects ≥ 55 years. Using automated pharmacy records, we evaluated statin use of 363 cases (COPD patients who died during follow-up of 17 years) with 2345 age and sex matched controls (COPD patients who survived the follow-up period of the index case). RESULTS: Compared to never use, long-term statin use (>2 years) was associated with a 39% decreased risk of death in COPD patients. Stratified according to the level of systemic inflammation, long-term statin use was associated with a 78% reduced mortality if hsCRP level > 3 mg/L, versus a non significant 21% reduced mortality if hsCRP level ≤ 3 mg/L. CONCLUSIONS: Statin use is associated with a beneficial effect on all-cause mortality in COPD, depending on the baseline level of systemic inflammation.

Genome-wide association studies identify CHRNA5/3 and HTR4 in the development of airflow obstruction.

RATIONALE: Genome-wide association studies (GWAS) have identified loci influencing lung function, but fewer genes influencing chronic obstructive pulmonary disease (COPD) are known. OBJECTIVES: Perform meta-analyses of GWAS for airflow obstruction, a key pathophysiologic characteristic of COPD assessed by spirometry, in population-based cohorts examining all participants, ever smokers, never smokers, asthma-free participants, and more severe cases. METHODS: Fifteen cohorts were studied for discovery (3,368 affected; 29,507 unaffected), and a population-based family study and a meta-analysis of case-control studies were used for replication and regional follow-up (3,837 cases; 4,479 control subjects). Airflow obstruction was defined as FEV(1) and its ratio to FVC (FEV(1)/FVC) both less than their respective lower limits of normal as determined by published reference equations. MEASUREMENTS AND MAIN RESULTS: The discovery meta-analyses identified one region on chromosome 15q25.1 meeting genome-wide significance in ever smokers that includes AGPHD1, IREB2, and CHRNA5/CHRNA3 genes. The region was also modestly associated among never smokers. Gene expression studies confirmed the presence of CHRNA5/3 in lung, airway smooth muscle, and bronchial epithelial cells. A single-nucleotide polymorphism in HTR4, a gene previously related to FEV(1)/FVC, achieved genome-wide statistical significance in combined meta-analysis. Top single-nucleotide polymorphisms in ADAM19, RARB, PPAP2B, and ADAMTS19 were nominally replicated in the COPD meta-analysis. CONCLUSIONS: These results suggest an important role for the CHRNA5/3 region as a genetic risk factor for airflow obstruction that may be independent of smoking and implicate the HTR4 gene in the etiology of airflow obstruction.

ERS International Congress 2022: highlights from the Interstitial Lung Diseases Assembly.

This article contains a selection of scientific highlights in the field of interstitial lung diseases (ILDs) presented at the hybrid European Respiratory Society International Congress 2022. Early Career Members of Assembly 12 summarise recent advances in translational and clinical research in idiopathic interstitial pneumonias, ILDs of known origin, sarcoidosis and other granulomatous diseases, and rare ILDs. Many studies focused on evaluation of diagnostic and prognostic (bio)markers, and novel pharmacological and nonpharmacological treatment options for different ILDs. In addition, new insights in clinical, physiological and radiological features of various rare ILDs were presented.

TRB sequences targeting ORF1a/b are associated with disease severity in hospitalized COVID-19 patients.

The potential protective or pathogenic role of the adaptive immune response to SARS-CoV-2 infection has been vigorously debated. While COVID-19 patients consistently generate a T lymphocyte response to SARS-CoV-2 antigens, evidence of significant immune dysregulation in these patients continues to accumulate. In this study, next generation sequencing of the T cell receptor beta chain (TRB) repertoire was conducted in hospitalized COVID-19 patients to determine if immunogenetic differences of the TRB repertoire contribute to disease course severity. Clustering of highly similar TRB CDR3 amino acid sequences across COVID-19 patients yielded 781 shared TRB sequences. The TRB sequences were then filtered for known associations with common diseases such as EBV and CMV. The remaining sequences were cross-referenced to a publicly accessible dataset that mapped COVID-19 specific TCRs to the SARS-CoV-2 genome. We identified 158 SARS-CoV-2 specific TRB sequences belonging to 134 clusters in our COVID-19 patients. Next, we investigated 113 SARS-CoV-2 specific clusters binding only one peptide target in relation to disease course. Distinct skewing of SARS-CoV-2 specific TRB sequences toward the nonstructural proteins (NSPs) encoded within ORF1a/b of the SARS-CoV-2 genome was observed in clusters associated with critical disease course when compared to COVID-19 clusters associated with a severe disease course. These data imply that T-lymphocyte reactivity towards peptides from NSPs of SARS-CoV-2 may not constitute an effective adaptive immune response and thus may negatively affect disease severity.

Regional Impact of COVID-19-Associated Pulmonary Aspergillosis (CAPA) during the First Wave.

BACKGROUND: Critically ill COVID-19 patients have proven to be at risk for developing invasive fungal infections. However, the incidence and impact of possible/probable COVID-19-associated pulmonary aspergillosis (CAPA) in severe COVID-19 patients varies between cohorts. We aimed to assess the incidence, risk factors, and clinical outcome of invasive pulmonary aspergillosis in a regional cohort of COVID-19 intensive care patients. METHODS: We performed a regional, multicentre, retrospective cohort study in the intensive care units (ICUs) in North Brabant, The Netherlands. We included adult patients with rt-PCR-confirmed SARS-CoV-2 infection (COVID-19), requiring mechanical ventilation for acute respiratory distress syndrome. Demographics, clinical course, biomarker value, and treatment outcomes were compared between the groups with possible/probable CAPA from the main study centre and the regional centres, and without signs of CAPA from the main study centre as controls. The primary aim was to assess the regional impact of possible/probable CAPA in COVID-19 ICU patients, measured as all-cause mortality at 30 days after ICU admission. Secondary outcomes were risk factors for developing CAPA, based on underlying host factors and to identify the value of the mycological arguments for the diagnosing of CAPA. RESULTS: Between 1 March and 30 April 2020, we included 123 patients with severe COVID-19: 29 patients (30.9%) in the main ICU with possible/probable CAPA, and 65 (69.1%) with no signs of CAPA; 29 patients in the regional ICUs with signs of CAPA. Patients' characteristics and risk factors did not differ for CAPA and non-CAPA patients. Patients with COPD and/or chronic steroid medication developed CAPA more frequently, although this was not statistically significant. CAPA patients were admitted to the ICU earlier, had lower PF-ratios, and more often required renal replacement therapy. All-cause 30-day mortality was significantly higher in mechanically ventilated COVID-19 patients with possible/probable CAPA 39.7% (23/58) compared to patients without evidence for CAPA 16.9% (11/65) (OR 3.2 [95% CI 1.4-7.4] p = 0.005). CONCLUSION: The high incidence of possible and probable CAPA in critically ill COVID-19 patients is alarming. The increase in 30-day mortality in CAPA highlights the need for active surveillance and management strategies in critically ill COVID-19 patients.

Mendelian randomization study of interleukin-6 in chronic obstructive pulmonary disease.

BACKGROUND: Cross-sectional studies have demonstrated that increased levels of interleukin-6 (IL6) are present in the airways and blood samples of patients with chronic obstructive pulmonary disease (COPD). OBJECTIVES: To investigate the association between IL6 and the risk of COPD using a Mendelian randomization approach. METHODS: Eight common single-nucleotide polymorphisms (SNPs) in the region of the IL6 gene were genotyped using both TaqMan and Illumina in the Rotterdam Study, a prospective population-based cohort study consisting of 7,983 participants aged 55 years or older, including 928 COPD patients. At baseline, blood was drawn in a random sample of 714 subjects to measure the IL6 plasma level. Analysis of variance, logistic regression, and Cox proportional hazard models--adjusted for age, gender, pack years, and BMI--were used for analyses. RESULTS: High levels of IL6 (>2.4 pg/ml, the highest tertile) were associated with a three-fold increased risk of developing COPD, in comparison to low levels (<1.4 pg/ml, the lowest tertile). The rs2056576 SNP was associated with a 10% increase in the risk of COPD per additional T allele. However, the association was no longer significant after adjustment. No association was found with other common SNPs in the IL6 gene and COPD. CONCLUSIONS: Although increased IL6 plasma levels at baseline are associated with the risk of developing COPD during follow-up, there was no strong evidence for an association between common variation in the IL6 gene and the risk of COPD.

Pulmonary function and diffusion capacity are associated with pulmonary arterial systolic pressure in the general population: The Rotterdam Study.

BACKGROUND: Pulmonary hypertension is a progressive heterogeneous syndrome, characterized by elevated pulmonary arterial pressure which can lead to right ventricular failure. Although the presence of elevated pulmonary arterial systolic pressure (PASP) in patients with a lung disease is a well-known occurrence, little is known about the association between pulmonary function and PASP in the general population. We hypothesized that pulmonary function and PASP are associated, irrespective of airflow limitation. METHODS: This study was performed within the Rotterdam Study, a prospective population-based cohort. We included 1660 participants with spirometry, performed and interpreted according to ATS/ERS-guidelines, and echocardiography performed according to the ASE/EAE/CSE-guidelines. We analyzed the association of Forced Expiratory Volume in 1 s (FEV1), Forced Vital Capacity (FVC), FEV1/FVC and diffusion capacity (DLCO) with estimated PASP (ePASP). Furthermore, we investigated the association between spirometry measures, COPD, and echocardiographic pulmonary hypertension. RESULTS: A 10% absolute decrease in FEV1 was associated with an ePASP increase of 0.46 mmHg (95%CI: 0.31; 0.61). Similarly, per absolute 10% decrease, FVC was significantly associated with an increased ePASP of 0.42 mmHg (95%CI: 0.25; 0.59). FEV1/FVC showed an association of 1.01 mmHg (95%CI: 0.58; 1.45) increase in ePASP per 10% absolute decrease. A decrease in DLCO (in mL/min/kPa) was associated with an increased ePASP (0.46 mmHg, 95%CI: 0.17; 0.76). We found significant associations for FEV1 and FVC with echocardiographic pulmonary hypertension. Importantly, an increased ePASP was significantly associated with mortality (Hazard Ratio: 1.042 per mmHg [95%CI: 1.023-1.062; p < 0.001]). CONCLUSION: We observed a clearly graded association between pulmonary function and ePASP and pulmonary hypertension, even in individuals without airflow limitation.

Evidence for large-scale gene-by-smoking interaction effects on pulmonary function.

Background: Smoking is the strongest environmental risk factor for reduced pulmonary function. The genetic component of various pulmonary traits has also been demonstrated, and at least 26 loci have been reproducibly associated with either FEV 1 (forced expiratory volume in 1 second) or FEV 1 /FVC (FEV 1 /forced vital capacity). Although the main effects of smoking and genetic loci are well established, the question of potential gene-by-smoking interaction effect remains unanswered. The aim of the present study was to assess, using a genetic risk score approach, whether the effect of these 26 loci on pulmonary function is influenced by smoking. Methods: We evaluated the interaction between smoking exposure, considered as either ever vs never or pack-years, and a 26-single nucleotide polymorphisms (SNPs) genetic risk score in relation to FEV 1 or FEV 1 /FVC in 50 047 participants of European ancestry from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) and SpiroMeta consortia. Results: We identified an interaction ( ßint = -0.036, 95% confidence interval, -0.040 to -0.032, P = 0.00057) between an unweighted 26 SNP genetic risk score and smoking status (ever/never) on the FEV 1 /FVC ratio. In interpreting this interaction, we showed that the genetic risk of falling below the FEV /FVC threshold used to diagnose chronic obstructive pulmonary disease is higher among ever smokers than among never smokers. A replication analysis in two independent datasets, although not statistically significant, showed a similar trend in the interaction effect. Conclusions: This study highlights the benefit of using genetic risk scores for identifying interactions missed when studying individual SNPs and shows, for the first time, that persons with the highest genetic risk for low FEV 1 /FVC may be more susceptible to the deleterious effects of smoking.

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.

Prevalence of Pulmonary Hypertension in the General Population: The Rotterdam Study.

BACKGROUND: Pulmonary hypertension is characterized by increased pulmonary artery pressure and carries an increased mortality. Population-based studies into pulmonary hypertension are scarce and little is known about its prevalence in the general population. We aimed to describe the distribution of echocardiographically-assessed pulmonary artery systolic pressure (ePASP) in the general population, to estimate the prevalence of pulmonary hypertension, and to identify associated factors. METHODS: Participants (n = 3381, mean age 76.4 years, 59% women) from the Rotterdam Study, a population-based cohort, underwent echocardiography. Echocardiographic pulmonary hypertension was defined as ePASP>40 mmHg. RESULTS: Mean ePASP was 26.3 mmHg (SD 7.0). Prevalence of echocardiographic pulmonary hypertension was 2.6% (95%CI: 2.0; 3.2). Prevalence was higher in older participants compared to younger ones (8.3% in those over 85 years versus 0.8% in those between 65 and 70), and in those with underlying disorders versus those without (5.9% in subjects with COPD versus 2.3%; 9.2% in those with left ventricular systolic dysfunction versus 2.3%; 23.1% in stages 3 or 4 left ventricular diastolic dysfunction versus 1.9% in normal or stage 1). Factors independently associated with higher ePASP were older age, higher BMI, left ventricular diastolic dysfunction, COPD and systemic hypertension. CONCLUSION: In this large population-based study, we show that pulmonary hypertension as measured by echocardiography has a low prevalence in the overall general population in the Netherlands, but estimates may be higher in specific subgroups, especially in those with underlying diseases. Increased pulmonary arterial pressure is likely to gain importance in the near future due to population aging and the accompanying prevalences of underlying disorders.