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Background: Severe α₁-antitrypsin deficiency is a known genetic risk factor for COPD. Heterozygous (protease inhibitor [PI] MZ) individuals have moderately reduced serum levels of α₁-antitrypsin, but whether they have an increased risk of COPD is uncertain.Methods: We compared PI MZ and PI MM individuals in two large populations: a case-control study from Norway (n = 1,669) and a multicenter family-based study from Europe and North America (n = 2,707). We sought to determine whether PI MZ was associated with the specific COPD-related phenotypes of lung function and quantitative CT scan measurements of emphysema and airway disease.Results: PI MZ was associated with a 3.5% lower FEV₁/FVC ratio in the case-control study (P = .035) and 3.9% lower FEV₁/vital capacity (VC) ratio in the family study (P = .009). In the case-control study, PI MZ also was associated with 3.7% more emphysema on quantitative analysis of chest CT scans (P = .003). The emphysema result was not replicated in the family study. PI MZ was not associated with airway wall thickness or COPD status in either population. Among subjects with low smoking exposure (< 20 pack-years), PI MZ individuals had more severe emphysema on chest CT scan than PI MM individuals in both studies.Conclusions: Compared with PI MM individuals, PI MZ heterozygotes had lower FEV₁/(F)VC ratio in two independent studies. Our results suggest that PI MZ individuals may be slightly more susceptible to the development of airflow obstruction than PI MM individuals. [ABSTRACT FROM AUTHOR]

Rationale: Several family-based studies have identified genetic linkage for lung function and airflow obstruction to chromosome 2q.Objectives: We hypothesized that merging results of high-resolution single nucleotide polymorphism (SNP) mapping in four separate populations would lead to the identification of chronic obstructive pulmonary disease (COPD) susceptibility genes on chromosome 2q.Methods: Within the chromosome 2q linkage region, 2,843 SNPs were genotyped in 806 COPD cases and 779 control subjects from Norway, and 2,484 SNPs were genotyped in 309 patients with severe COPD from the National Emphysema Treatment Trial and 330 community control subjects. Significant associations from the combined results across the two case-control studies were followed up in 1,839 individuals from 603 families from the International COPD Genetics Network (ICGN) and in 949 individuals from 127 families in the Boston Early-Onset COPD Study.Measurements and Main Results: Merging the results of the two case-control analyses, 14 of the 790 overlapping SNPs had a combined P < 0.01. Two of these 14 SNPs were consistently associated with COPD in the ICGN families. The association with one SNP, located in the gene XRCC5, was replicated in the Boston Early-Onset COPD Study, with a combined P = 2.51 x 10(-5) across the four studies, which remains significant when adjusted for multiple testing (P = 0.02). Genotype imputation confirmed the association with SNPs in XRCC5.Conclusions: By combining data from COPD genetic association studies conducted in four independent patient samples, we have identified XRCC5, an ATP-dependent DNA helicase, as a potential COPD susceptibility gene. [ABSTRACT FROM AUTHOR]

Rationale: Damage to airway epithelium is followed by deposition of extracellular matrix (ECM) and migration of adjacent epithelial cells. We have shown that epithelial cells from children with asthma fail to heal a wound in vitro.Objectives: To determine whether dysregulated ECM production by the epithelium plays a role in aberrant repair in asthma.Methods: Airway epithelial cells (AEC) from children with asthma (n = 36), healthy atopic control subjects (n = 23), and healthy nonatopic control subjects (n = 53) were investigated by microarray, gene expression and silencing, transcript regulation analysis, and ability to close mechanical wounds.Measurements and Main Results: Time to repair a mechanical wound in vitro by AEC from healthy and atopic children was not significantly different and both were faster than AEC from children with asthma. Microarray analysis revealed differential expression of multiple gene sets associated with repair and remodeling in asthmatic AEC. Fibronectin (FN) was the only ECM component whose expression was significantly lower in asthmatic AEC. Expression differences were verified by quantitative polymerase chain reaction and ELISA, and reduced FN expression persisted in asthmatic cells over passage. Silencing of FN expression in nonasthmatic AEC inhibited wound repair, whereas addition of FN to asthmatic AEC restored reparative capacity. Asthmatic AEC failed to synthesize FN in response to wounding or cytokine/growth factor stimulation. Exposure to 5', 2'deoxyazacytidine had no effect on FN expression and subsequent analysis of the FN promoter did not show evidence of DNA methylation.Conclusions: These data show that the reduced capacity of asthmatic epithelial cells to secrete FN is an important contributor to the dysregulated AEC repair observed in these cells. [ABSTRACT FROM AUTHOR]

Background: A study was undertaken to determine if quantitative CT estimates of lung parenchymal overinflation and airway dimensions in smokers with a normal forced expiratory volume in 1 s (FEV(1)) can predict the rapid decline in FEV(1) that leads to chronic obstructive pulmonary disease (COPD).Methods: Study participants (n = 143; age 45-72 years; 54% male) were part of a lung cancer screening trial, had a smoking history of >30 pack years and a normal FEV(1) and FEV(1)/forced vital capacity (FVC) at baseline (mean (SD) FEV(1) 99.4 (12.8)%, range 80.2-140.7%; mean (SD) FEV(1)/FVC 77.9 (4.4), range 70.0-88.0%). An inspiratory multislice CT scan was acquired for each subject at baseline. Custom software was used to measure airway lumen and wall dimensions; the percentage of the lung inflated beyond a predicted maximal lung inflation, the low attenuation lung area with an x ray attenuation lower than -950 HU and the size distribution of the overinflated lung areas and the low attenuation area were described using a cluster analysis. Multiple regression analysis was used to test the hypothesis that these CT measurements combined with other baseline characteristics might identify those who would develop an excessive annual decline in FEV(1).Results: The mean (SD) annual change in FEV(1) was -2.3 (4.7)% predicted (range -23.0% to +8.3%). Multiple regression analysis revealed that the annual change in FEV(1)%predicted was significantly associated with baseline percentage overinflated lung area measured on quantitative CT, FEV(1)% predicted, FEV(1)/FVC and gender.Conclusion: Quantitative CT scan evidence of overinflation of the lung predicts a rapid annual decline in FEV(1) in smokers with normal FEV(1). [ABSTRACT FROM AUTHOR]

Background: Chronic obstructive pulmonary disease (COPD) is characterised by the presence of airflow limitation caused by loss of lung elasticity and/or airway narrowing. The pathological hallmark of loss of lung elasticity is emphysema, and airway wall remodelling contributes to the airway narrowing. Using CT, these lesions can be assessed by measuring low attenuation areas (LAA) and airway wall thickness/luminal area, respectively. As previously reported, COPD can be divided into airway dominant, emphysema dominant and mixed phenotypes using CT. In this study, it is postulated that a patient's physique may be associated with the relative contribution of these lesions to airflow obstruction. Methods: CT was used to evaluate emphysema and airway dimensions in 201 patients with COPD. Emphysema was evaluated using percentage of LAA voxels (LAA%) and airway lesion was estimated by percentage wall area (WA%). Patients were divided into four phenotypes using LAA% and WA%. Results: Body mass index (BMI) was significantly lower in the higher LAA% phenotype (ie, emphysema dominant and mixed phenotypes). BMI correlated with LAA% (rho = -0.557, p<0.0001) but not with WA%. BMI was significantly lower in the emphysema dominant phenotype than in the airway dominant phenotype, while there was no difference in forced expiratory volume in 1 s %predicted between the two. Conclusion: A low BMI is associated with the presence of emphysema, but not with airway wall thickening, in male smokers who have COPD. These results support the concept of different COPD phenotypes and suggest that there may be different systemic manifestations of these phenotypes. [ABSTRACT FROM AUTHOR]

Rationale: It is unclear whether airway wall thickening and emphysema make independent contributions to airflow limitation in chronic obstructive pulmonary disease (COPD) and whether these phenotypes cluster within families.Objectives: To determine whether airway wall thickening and emphysema (1) make independent contributions to the severity of COPD and (2) show independent aggregation in families of individuals with COPD.Methods: Index cases with COPD and their smoking siblings underwent spirometry and were offered high-resolution computed tomography scans of the thorax to assess the severity of airway wall thickening and emphysema.Measurements and Main Results: A total of 3,096 individuals were recruited to the study, of whom 1,159 (519 probands and 640 siblings) had technically adequate high-resolution computed tomography scans without significant non-COPD-related thoracic disease. Airway wall thickness correlated with pack-years smoked (P < or = 0.001) and symptoms of chronic bronchitis (P < 0.001). FEV(1) (expressed as % predicted) was independently associated with airway wall thickness at a lumen perimeter of 10 mm (P = 0.0001) and 20 mm (P = 0.0013) and emphysema at -950 Hounsfield units (P < 0.0001). There was independent familial aggregation of both the emphysema (adjusted odds ratio, 2.1; 95% confidence interval, 1.1-4.0; P < or = 0.02) and airway disease phenotypes (P < 0.0001) of COPD.Conclusions: Airway wall thickening and emphysema make independent contributions to airflow obstruction in COPD. These phenotypes show independent aggregation within families of individuals with COPD, suggesting that different genetic factors influence these disease processes. [ABSTRACT FROM AUTHOR]

Smoking-related lung diseases such as chronic obstructive pulmonary disease (COPD) and lung cancer are growing epidemics in women in the United States and elsewhere. Although some of this disturbing trend in women can be attributed to changing smoking habits, there is emerging evidence that women may be biologically more susceptible to the harmful effects of cigarette smoke than are men. Estrogen and related compounds may up-regulate the expression of cytochrome P450 (CYP) enzymes in lungs and liver, which are involved in the metabolism of various constituents of cigarette smoke. Although metabolism of foreign substances is usually beneficial in eliminating potential toxins from the body, in some instances the metabolic process can transform harmless substances into toxic chemicals through a process called metabolic bioactivation. One important xenobiotic substrate for CYP enzymes in cigarette smoke is polycyclic aromatic hydrocarbon, which in its native form is relatively harmless in small doses but upon bioactivation by CYP enzymes, can become very toxic substances for the lungs. In this article, we explore CYP and other related pathways as potential mechanisms and targets of future research and novel discoveries to curb the growing epidemic of COPD and lung cancer in women. [ABSTRACT FROM AUTHOR]

Rationale: In cystic fibrosis (CF), chronic bacterial infection and inflammation lead to progressive airway wall thickening and lumen dilatation. Objectives: To quantify airway wall thickening and lumen dilatation in children with CF over a 2-year interval. Methods: Children with CF (n = 23) who had two computed tomography (CT) scans (CT(cf1) and CT(cf2)) combined with pulmonary function tests (PFTs), with a 2-year interval between measurements, were compared with control subjects (n = 21) who had one CT (CT(controls)). On cross-sectional cut airway-artery pairs, airway wall area (WA), airway lumen area (LA) and perimeter, and arterial area (AA) were quantified. LA/AA (= marker of bronchiectasis), airway wall thickness (AWT), and WA/AA (= markers of wall thickness) were calculated. CT scans were scored using four different scoring systems. PFTs were expressed as percent predicted. Results: Airway WA-to-AA ratio was 1.45 (p < 0.001) and airway LA-to-AA ratio was 1.92 times higher (p < 0.001) in children with CF compared with age-matched control subjects. LA/AA and WA/AA remained unchanged from CT(cf1) to CT(cf2) and did not increase with age. AWT as a function of airway size increased from CT(cf1) to CT(cf2) by 2% (0.03 mm; p = 0.02). The change in AWT was inversely related to the change in forced expiratory flow between 25 and 75% of expiratory VC (p = 0.002). Conclusions: In CF, quantitative measurements of airways on CT scans show an increased ratio between airway LA and AA and progressive airway wall thickening. Scoring systems show progression of bronchiectasis but unchanged AWT. PFTs remained stable. [ABSTRACT FROM AUTHOR]

Chronic obstructive pulmonary disease is characterized by destruction of the lung parenchyma and/or small airway narrowing. To determine whether the dimensions of relatively large airways assessed using computed tomography (CT) reflect small airway dimensions measured histologically, we assessed these variables in nonobstructed or mild to moderately obstructed patients having lobar resection for a peripheral tumor. For both CT and histology, the square root of the airway wall area (Aaw) was plotted versus lumen perimeter to estimate wall thickness. The wall area percentage was calculated as wall area/lumen area + wall area x 100. Although CT overestimated Aaw, the slopes of the relationships between the square root of Aaw and internal perimeter (Pi) measured with both techniques were related (CT slope = 0.2059 histology slope + 0.1701, R2 = 0.32, p < 0.01). The mean wall area percentage measured by CT for airways with a Pi of greater than 0.75 cm predicted the mean dimensions of the small airways with an internal diameter of 1.27 mm (R2 = 0.57, p < 0.01). We conclude that CT measurements of airways with a Pi of 0.75 cm or more could be used to estimate the dimensions of the small conducting airways, which are the site of airway obstruction in chronic obstructive pulmonary disease. [ABSTRACT FROM AUTHOR]

STUDY OBJECTIVE: To assess the association between socioeconomic status (SES) and short-acting (SA) beta-agonist use, controlling for asthma severity. DESIGN: Cross-sectional study. SETTING: Vancouver, BC, Canada. PARTICIPANTS: Two hundred two asthmatics between 19 years and 50 years of age and residing in the greater Vancouver regional district. MEASUREMENTS: The quantity of SA beta-agonist used in the previous year was collected by self-report; pulmonary function and beta-receptor genotype were measured on each participant. SES was measured at both the individual and population levels. Five methods of adjustment for asthma severity were used, as follows: the Canadian Asthma Consensus Guidelines, three previously developed asthma-severity scores, and forward stepwise multiple regression modeling. Polychotomous logistic regression was used to assess all relationships. RESULTS: Independent of the method used to measure SES or adjust for asthma severity, lower SES was consistently and significantly associated with the use of greater amounts of SA beta-agonist. Adjusting for severity using the multivariate model explained the most variance of SA beta-agonist use (R(2) adjusted, 0.35 to 0.37). In this model, social assistance recipients were more likely to use greater amounts of SA beta-agonist (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.7 to 6.5). An inverse relationship between SA beta-agonist use and both annual household income (> $50,000; OR, 0.28; 95% CI, 0.13 to 0.60; and $20,000 to $50,000; OR, 0.44; 95% CI, 0.21 to 0.96; relative to <$20,000) and education (completing a bachelor's degree vs no formal education; OR, 0.25; 95% CI, 0.14 to 0.71). Participants living in a neighborhood with higher median household income (OR, 0.91; 95% CI, 0.84 to 0.98 per $1,000 increase) or a higher prevalence of having attained a bachelor's degree (OR, 0.96; 95% CI, 0.84 to 0.98 per 1% increase) were also less likely use greater amounts of SA beta-agonist. Results were consistent for neighborhood unemployment rate. CONCLUSIONS: The social gradient in asthma-related outcomes may be at least partially attributable to poorer asthma control in lower-SES asthmatics. [ABSTRACT FROM AUTHOR]

We studied glutathione S-transferase (GST) polymorphisms in 1,098 whites with the lowest (n = 544, FEV(1) % predicted mean +/- SEM = 62.6 +/- 0.1) and the highest (n = 554, FEV(1) % predicted mean +/- SEM = 91.8 +/- 0.1) lung function at the beginning of the Lung Health Study. Homozygosity for GSTP1 105Val was significantly more frequent in the low- than in the high-function group (13.2 vs. 9.3%) (odds ratio = 1.69, 95% confidence interval [CI] = 1.11-2.61, p = 0.016), after adjustment for confounding variables. Subjects with 105Val homozygotes had higher rates of lung function decline in the high-function group (p = 0.017). The frequencies of GSTM1, GSTT1 null genotypes were similar between the high- and low-function groups, but subjects with the GSTT1 null genotype had a faster decline of lung function in the low-function group (p = 0.032). In addition, there was a significant interaction of GSTT1 genotype and pack-years on lung function. When comparing individuals with GSTT1 null genotype with wild type, the adjusted odds ratio was 3.49 (95% CI, 1.48-8.39, p = 0.005) in mild smokers (< or = 25 pack years). We conclude that GST genotypes are risk factors for rapid decline or low lung function in smokers with mild to moderate airflow obstruction. [ABSTRACT FROM AUTHOR]

Study Objectives: To assess trends in asthma management and to identify factors associated with increasing short-acting (SA) beta-agonist utilization in British Columbia using administrative prescription data.Design: A retrospective cohort analysis.Setting: All patients between 13 and 50 years of age who had received at least one prescription for a SA beta-agonist covered by BC Pharmacare between January 1, 1996, and December 31, 1998.Methods: Cross-sectional analysis of all patients, and longitudinal analyses only of patients who had received at least one SA beta-agonist prescription in each of the 3 years. Trends in asthma medication use over time were evaluated using repeated-measures Mantel-Haenszel tests. Multiple logistic regression was used to identify factors associated with increasing SA beta-agonist use.Results: A total of 78,758 patients were included in the cohort. No decrease in the annual prevalence of receiving more than four canisters per year of a SA beta-agonist was identified between 1996 and 1998. A total of 12,844 patients filled at least one SA beta-agonist prescription each year. Time-trend analysis showed an overall increasing probability of not receiving an inhaled corticosteroid (ICS) agent in this population (p = 0.002). In patients exhibiting low SA beta-agonist use, > 18 years of age (adjusted odds ratio [OR], 1.5), male gender (adjusted OR, 1.7), and in receipt of social assistance (adjusted OR, 2.3) were associated with receiving increasing amounts of SA beta-agonist agents over the 3 years. In patients with a high degree of use of SA beta-agonists, only the receipt of social assistance (adjusted OR, 1.3) was significantly associated with increasing use.Conclusions: Despite the development and dissemination of asthma management guidelines, there was no trend toward decreasing SA beta-agonist use. An unexpected trend toward decreasing ICS utilization was identified. Receiving social assistance was a risk factor for increasing SA beta-agonist use, independent of baseline utilization. [ABSTRACT FROM AUTHOR]

Rationale: Emerging data demonstrate that the smallest conducting airways, terminal bronchioles, are the early site of tissue destruction in chronic obstructive pulmonary disease (COPD) and are reduced by as much as 41% by the time someone is diagnosed with mild (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 1) COPD. Objectives: To develop a single-cell atlas that describes the structural, cellular, and extracellular matrix alterations underlying terminal bronchiole loss in COPD. Methods: This cross-sectional study of 262 lung samples derived from 34 ex-smokers with normal lung function ( n  = 10) or GOLD stage 1 ( n  = 10), stage 2 ( n  = 8), or stage 4 ( n  = 6) COPD was performed to assess the morphology, extracellular matrix, single-cell atlas, and genes associated with terminal bronchiole reduction using stereology, micro-computed tomography, nonlinear optical microscopy, imaging mass spectrometry, and transcriptomics. Measurements and Main Results: The lumen area of terminal bronchioles progressively narrows with COPD severity as a result of the loss of elastin fibers within alveolar attachments, which was observed before microscopic emphysematous tissue destruction in GOLD stage 1 and 2 COPD. The single-cell atlas of terminal bronchioles in COPD demonstrated M1-like macrophages and neutrophils located within alveolar attachments and associated with the pathobiology of elastin fiber loss, whereas adaptive immune cells (naive, CD4, and CD8 T cells, and B cells) are associated with terminal bronchiole wall remodeling. Terminal bronchiole pathology was associated with the upregulation of genes involved in innate and adaptive immune responses, the interferon response, and the degranulation of neutrophils. Conclusions: This comprehensive single-cell atlas highlights terminal bronchiole alveolar attachments as the initial site of tissue destruction in centrilobular emphysema and an attractive target for disease modification.

Lung resistance ( R L ) is determined by airway and parenchymal tissue resistance, as well as the degree of heterogeneity in airway constriction. Deep inspirations (DIs) are known to reverse experimentally induced increase in R L , but the mechanism is not entirely clear. The first step toward understanding the effect of DI is to determine how each of the resistance components is affected by DI. In the present study, we measured R L and apparent airway resistance ( R AW , which combines the effects of airway resistance and airway heterogeneity) simultaneously before and after a DI in acetylcholine (ACh)-challenged ex vivo sheep lungs. We found that at normal breathing frequency (0.25 Hz) ACh-challenge led to a doubling of R L , 80.3% of that increase was caused by an increase in R AW ; the increase in apparent tissue resistance ( R T ) was insignificant. 57.7% of the increase in R AW was abolished by a single DI. After subtracting R AW from R L , the remaining R T was mostly independent of ACh-challenge and its reduction after a DI came mostly from the change in the mechanical properties of lung parenchyma. We conclude that at normal breathing frequency, R L in an unchallenged lung is mostly composed of R T , and the increase in R L due to ACh-challenge stems mostly from the increase in R AW and that both R AW and R T can be greatly reduced by a DI, likely due to a reduction in true airway resistance and heterogeneity, as well as parenchymal tissue hysteresis post DI.

Lung resistance ( R L ) and elastance ( E L ) can be measured during positive or negative pressure ventilation. Whether the different modes of ventilation produce different R L and E L is still being debated. Although negative pressure ventilation (NPV) is more physiological, positive pressure ventilation (PPV) is more commonly used for treating respiratory failure. In the present study, we measured lung volume, airway diameter, and airway volume, as well as R L and E L with PPV and NPV in explanted sheep lungs. We found that lung volume under a static pressure, either positive or negative, was not different. However, R L and E L were significantly higher in NPV at high inflation pressures. Interestingly, diameters of smaller airways (diameters <3.5 mm) and total airway volume were significantly greater at high negative inflation pressures compared with those at high positive inflation pressures. This suggests that NPV is more effective in distending the peripheral airways, likely due to the fact that negative pressure is applied through the pleural membrane and reaches the central airways via the peripheral airways, whereas positive pressure is applied in the opposite direction. More distension of lung periphery could explain why R L is higher in NPV (vs. PPV), because the peripheral parenchyma is a major source of tissue resistance, which is a part of the R L that increases with pressure. This explanation is consistent with the finding that during high frequency ventilation (>1 Hz, where R L reflects airway resistance more than tissue resistance), the difference in R L between NPV and PPV disappeared.

Rationale: To improve disease outcomes in idiopathic pulmonary fibrosis (IPF), it is essential to understand its early pathophysiology so that it can be targeted therapeutically. Objectives: Perform three-dimensional assessment of the IPF lung microstructure using stereology and multiresolution computed tomography (CT) imaging. Methods: Explanted lungs from patients with IPF ( n  = 8) and donor control subjects ( n  = 8) were inflated with air and frozen. CT scans were used to assess large airways. Unbiased, systematic uniform random samples ( n  = 8/lung) were scanned with microCT for stereological assessment of small airways (count number, and measure airway wall and lumen area) and parenchymal fibrosis (volume fraction of tissue, alveolar surface area, and septal wall thickness). Measurements and Main Results: The total number of airways on clinical CT was greater in IPF lungs than control lungs ( P  < 0.01), owing to an increase in the wall ( P  < 0.05) and lumen area ( P  < 0.05) resulting in more visible airways with a lumen larger than 2 mm. In IPF tissue samples without microscopic fibrosis, assessed by the volume fraction of tissue using microCT, there was a reduction in the number of the terminal ( P  < 0.01) and transitional ( P  < 0.001) bronchioles, and an increase in terminal bronchiole wall area ( P  < 0.001) compared with control lungs. In IPF tissue samples with microscopic parenchymal fibrosis, terminal bronchioles had increased airway wall thickness ( P  < 0.05) and dilated airway lumens ( P  < 0.001) leading to honeycomb cyst formations. Conclusions: This study has important implications for the current thinking on how the lung tissue is remodeled in IPF and highlights small airways as a potential target to modify IPF outcomes.

Deep inspiration (DI)-induced bronchodilation is the first line of defense against bronchoconstriction in healthy subjects. A hallmark of asthma is the lack of this beneficial effect of DI. The mechanism underlying the bronchodilatory effect of DI is not clear. Understanding the mechanism will help us unravel the mystery of asthma pathophysiology. It has been postulated that straining airway smooth muscle (ASM) during a DI could lead to bronchodilation and bronchoprotection. The hypothesis is currently under debate, and a central question is whether ASM is sufficiently stretched during a DI for its contractility to be compromised. Besides bronchoconstriction, another contributor to lung resistance is airway heterogeneity. The present study examines changes in airway diameter and heterogeneity at different lung volumes. Freshly explanted sheep lungs were used in plethysmographic measurements of lung resistance and elastance at different lung volumes, whereas the airway dimensions were measured by computed tomography (CT). The change in airway diameter informed by CT measurements was applied to isolated airway ring preparations to determine the strain-induced loss of ASM contractility. We found that changing the transpulmonary pressure from 5 to 30 cmH 2 O led to a 51% increase in lung volume, accompanied by a 46% increase in the airway diameter with no change in airway heterogeneity. When comparable airway strains measured in the whole lung were applied to isolated airway rings in either relaxed or contracted state, a significant loss of ASM contractility was observed, suggesting that DI-induced bronchodilation and bronchoprotection can result from strain-induced loss of ASM contractility.

Rationale: Although centrilobular emphysema (CLE) and paraseptal emphysema (PSE) are commonly identified on multidetector computed tomography (MDCT), little is known about the pathology associated with PSE compared with that of CLE. Objectives: To assess the pathological differences between PSE and CLE in chronic obstructive pulmonary disease (COPD). Methods: Air-inflated frozen lung specimens ( n  = 6) obtained from patients with severe COPD treated by lung transplantation were scanned with MDCT. Frozen tissue cores were taken from central ( n  = 8) and peripheral ( n  = 8) regions of each lung, scanned with micro-computed tomography (microCT), and processed for histology. The core locations were registered to the MDCT, and a percentage of PSE or CLE was assigned by radiologists to each of the regions. MicroCT scans were used to measure number and structural change of terminal bronchioles. Furthermore, microCT-based volume fractions of CLE and PSE allowed classifying cores into mild emphysema, CLE-dominant, and PSE-dominant. Measurements and Main Results: The percentages of PSE measured on MDCT and microCT were positively associated ( P  = 0.015). The number of terminal bronchioles per milliliter of lung and cross-sectional lumen area were significantly lower and wall area percentage was significantly higher in CLE-dominant regions compared with mild emphysema and PSE-dominant regions (all P  < 0.05), whereas no difference was found between PSE-dominant and mild emphysema samples (all P  > 0.5). Immunohistochemistry showed significantly higher infiltration of neutrophils ( P  = 0.002), but not of macrophages, CD4, CD8, or B cells, in PSE compared with CLE regions. Conclusions: The terminal bronchioles are relatively preserved, whereas neutrophilic inflammation is increased in PSE-dominant regions compared with CLE-dominant regions in patients with COPD.

Patients who have chronic obstructive pulmonary disease (COPD) and bronchial asthma (BA) share symptoms such as, dyspnoea, cough and wheeze. Differentiating these diseases in the ambulatory setting can be challenging especially in older adult smokers who are being treated with a variety of medications. The objective of this study was to test the value of adding a maximal inspiratory manoeuvre to basic spirometry to differentiate COPD and BA. One hundred forty-three COPD patients and 142 BA patients had measurements of maximal inspiratory and expiratory flow during routine spirometry. Parameters from these tests were used to assess diagnostic accuracy using receiver-operating characteristic (ROC) analyses followed by logistic regression. The association of two independent parameters were analyzed using linear regression analyses. Results show that forced expiratory volume in one second/forced vital capacity (FEV 1 /FVC%) <62.4 was the best independent predictor to diagnose COPD. The combination of FEV 1 /FVC% <62.4 and the ratio of peak inspiratory flow/maximal expiratory flow at 50% FVC (PIF/MEF 50 ) >3.06 significantly predicted COPD. Post-test probability for prediction of COPD was 82.0% when patients had both parameters. When asthmatic patients with a smoking history were compared with COPD patients, FEV 1 /FVC% <63.4 and PIF/MEF 50 >3.29 were both independent predictors of COPD. The post-test probability for COPD was 94.4% when patients had both parameters. The association between FEV 1 /FVC% and PIF/MEF 50 was significantly different between COPD and BA. In conclusion, the addition of the maximal inspiratory effort to routine pulmonary function measurements provides a simple test to help differentiate COPD and BA.

The cyclic interaction between myosin crossbridges and actin filaments underlies smooth muscle contraction. Phosphorylation of the 20-kDa myosin light chain (MLC20) is a crucial step in activating the crossbridge cycle. Our current understanding of smooth muscle contraction is based on observed correlations among MLC20 phosphorylation, maximal shortening velocity ( V max ), and isometric force over the time course of contraction. However, during contraction there are changes in the extent of phosphorylation of many additional proteins as well as changes in activation of enzymes associated with the signaling pathways. As a consequence, the mechanical manifestation of muscle contraction is likely to change with time. To simplify the study of these relationships, we measured the mechanical properties of airway smooth muscle at different levels of MLC20 phosphorylation at a fixed time during contraction. A simple correlation emerged when time-dependent variables were fixed. MLC20 phosphorylation was found to be directly and linearly correlated with the active stress, stiffness, and power of the muscle; the observed weak dependence of V max on MLC20 phosphorylation could be explained by the presence of an internal load in the muscle preparation. These results can be entirely explained by the Huxley crossbridge model. We conclude that when the influence of time-dependent events during contraction is held constant, the basic crossbridge mechanism in smooth muscle is the same as that in striated muscle.

Background: Airflow obstruction is a hallmark of chronic obstructive pulmonary disease (COPD), and is defined as either the ratio between forced expiratory volume in one second and forced vital capacity (FEV 1 /FVC) < 70% or < lower limit of normal (LLN). This study aimed to assess the overlap between genome-wide association studies (GWAS) on airflow obstruction using these two definitions in the same population stratified by smoking., Methods: GWASes were performed in the LifeLines Cohort Study for both airflow obstruction definitions in never-smokers (NS = 5071) and ever-smokers (ES = 4855). The FEV 1 /FVC < 70% models were adjusted for sex, age, and height; FEV 1 /FVC < LLN models were not adjusted. Ever-smokers models were additionally adjusted for pack-years and current-smoking. The overlap in significantly associated SNPs between the two definitions and never/ever-smokers was assessed using several p-value thresholds. To quantify the agreement, the Pearson correlation coefficient was calculated between the p-values and ORs. Replication was performed in the Vlagtwedde-Vlaardingen study (NS = 432, ES = 823). The overlapping SNPs with p < 10 - 4 were validated in the Vlagtwedde-Vlaardingen and Rotterdam Study cohorts (NS = 1966, ES = 3134) and analysed for expression quantitative trait loci (eQTL) in lung tissue (n = 1087)., Results: In the LifeLines cohort, 96% and 93% of the never- and ever-smokers were classified concordantly based on the two definitions. 26 and 29% of the investigated SNPs were overlapping at p < 0.05 in never- and ever-smokers, respectively. At p < 10 - 4 the overlap was 4% and 6% respectively, which could be change findings as shown by simulation studies. The effect estimates of the SNPs of the two definitions correlated strongly, but the p-values showed more variation and correlated only moderately. Similar observations were made in the Vlagtwedde-Vlaardingen study. Two overlapping SNPs in never-smokers (NFYC and FABP7) had the same direction of effect in the validation cohorts and the NFYC SNP was an eQTL for NFYC-AS1. NFYC is a transcription factor that binds to several known COPD genes, and FABP7 may be involved in abnormal pulmonary development., Conclusions: The definition of airflow obstruction and the population under study may be important determinants of which SNPs are associated with airflow obstruction. The genes FABP7 and NFYC(-AS1) could play a role in airflow obstruction in never-smokers specifically.

Genome-wide association studies have linked gene variants of the receptor patched homolog 1 (PTCH1) with chronic obstructive pulmonary disease (COPD). However, its biological role in the disease is unclear. Our objective was to determine the expression pattern and biological role of PTCH1 in the lungs of patients with COPD. Airway epithelial-specific PTCH1 protein expression and epithelial morphology were assessed in lung tissues of control and COPD patients. PTCH1 mRNA expression was measured in bronchial epithelial cells obtained from individuals with and without COPD. The effects of PTCH1 siRNA knockdown on epithelial repair and mucous expression were evaluated using human epithelial cell lines. Ptch1 +/- mice were used to assess the effect of decreased PTCH1 on mucous expression and airway epithelial phenotypes. Airway epithelial-specific PTCH1 protein expression was significantly increased in subjects with COPD compared to controls, and its expression was associated with total airway epithelial cell count and thickness. PTCH1 knockdown attenuated wound closure and mucous expression in airway epithelial cell lines. Ptch1 +/- mice had reduced mucous expression compared to wildtype mice following mucous induction. PTCH1 protein is up-regulated in COPD airway epithelium and may upregulate mucous expression. PTCH1 provides a novel target to reduce chronic bronchitis in COPD patients.

Asthmatic airways are stiffer than normal. We have shown that the cytoskeletal passive stiffness of airway smooth muscle (ASM) can be regulated by intracellular signaling pathways, especially those associated with Rho kinase (ROCK). We have also shown that an oscillatory strain reduces the passive stiffness of ASM and its ability to generate force. Here, we investigated the combined effect of inhibiting the ASM contraction with β 2 agonist and decreasing the ASM cytoskeletal stiffness with ROCK inhibitor and/or force oscillation (FO) on the relaxation of contracted ASM. We hypothesize that the ASM relaxation can be synergistically enhanced by the combination of these interventions, because drug-induced softening of the cytoskeleton enhances the FO-induced relaxation and vice versa. Sheep tracheal strips were isotonically contracted to acetylcholine (3 × 10 -5 M). At the plateau of shortening, β 2 agonist salbutamol (10 -7 M), ROCK inhibitor H1152 (10 -7 M), and FO (square wave, 1 Hz, amplitude 6% maximal active force) were applied either alone or in combination. After adjusting for nonspecific time-dependent variation, relengthening by individual interventions with low-dose salbutamol or H1152, or small amplitude FO was not significantly different from zero. However, significant relengthening was observed in all combination treatments. The relengthening was greater than the mathematical sum of relengthening caused by individual treatments thereby demonstrating synergistic relaxation. The ASM stiffness did not change with salbutamol or H1152 treatments, but was lower with FO in combination with H1152. The results suggest that the mechanopharmacological treatment can be an effective therapy for asthma., (Copyright © 2019 by ASME.)

Respiratory symptoms are important indicators of respiratory diseases. Both genetic and environmental factors contribute to respiratory symptoms development but less is known about gene-environment interactions. We aimed to assess interactions between single nucleotide polymorphisms (SNPs) and occupational exposures on respiratory symptoms cough, dyspnea and phlegm. As identification cohort LifeLines I (n = 7976 subjects) was used. Job-specific exposure was estimated using the ALOHA + job exposure matrix. SNP-by-occupational exposure interactions on respiratory symptoms were tested using logistic regression adjusted for gender, age, and current smoking. SNP-by-exposure interactions with a p-value <10 -4 were tested for replication in two independent cohorts: LifeLines II (n = 5260) and the Vlagtwedde-Vlaardingen cohort (n = 1529). The interaction estimates of the replication cohorts were meta-analyzed using PLINK. Replication was achieved when the meta-analysis p-value was <0.05 and the interaction effect had the same direction as in the identification cohort. Additionally, we assessed whether replicated SNPs associated with gene expression by analyzing if they were cis-acting expression quantitative trait loci (eQTL) in lung tissue. In the replication meta-analysis, sixteen out of 477 identified SNP-by-occupational exposure interactions had a p-value <0.05 and 9 of these interactions had the same direction as in the identification cohort. Several identified loci were plausible candidates for respiratory symptoms, such as TMPRSS9, SERPINH1, TOX3, and ARHGAP18. Three replicated SNPs were cis-eQTLs for FCER1A, CHN1, and TIMM13 in lung tissue. Taken together, this genome-wide SNP-by-occupational exposure interaction study in relation to cough, dyspnea, and phlegm identified several suggestive susceptibility genes. Further research should determine if these genes are true susceptibility loci for respiratory symptoms in relation to occupational exposures., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Chronic obstructive pulmonary disease (COPD), one of the leading causes of death worldwide, is substantially influenced by genetic factors. Alpha-1 antitrypsin deficiency demonstrates that rare coding variants of large effect can influence COPD susceptibility. To identify additional rare coding variants in patients with severe COPD, we conducted whole exome sequencing analysis in 2543 subjects from two family-based studies (Boston Early-Onset COPD Study and International COPD Genetics Network) and one case-control study (COPDGene). Applying a gene-based segregation test in the family-based data, we identified significant segregation of rare loss of function variants in TBC1D10A and RFPL1 (P-value < 2x10-6), but were unable to find similar variants in the case-control study. In single-variant, gene-based and pathway association analyses, we were unable to find significant findings that replicated or were significant in meta-analysis. However, we found that the top results in the two datasets were in proximity to each other in the protein-protein interaction network (P-value = 0.014), suggesting enrichment of these results for similar biological processes. A network of these association results and their neighbors was significantly enriched in the transforming growth factor beta-receptor binding and cilia-related pathways. Finally, in a more detailed examination of candidate genes, we identified individuals with putative high-risk variants, including patients harboring homozygous mutations in genes associated with cutis laxa and Niemann-Pick Disease Type C. Our results likely reflect heterogeneity of genetic risk for COPD along with limitations of statistical power and functional annotation, and highlight the potential of network analysis to gain insight into genetic association studies.

Inadequate DNA repair is implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, the mechanisms that underlie inadequate DNA repair in COPD are poorly understood. We applied an integrative genomic approach to identify DNA repair genes and pathways associated with COPD severity.We measured the transcriptomic changes of 419 genes involved in DNA repair and DNA damage tolerance that occur with severe COPD in three independent cohorts (n=1129). Differentially expressed genes were confirmed with RNA sequencing and used for patient clustering. Clinical and genome-wide transcriptomic differences were assessed following cluster identification. We complemented this analysis by performing gene set enrichment analysis, Z-score and weighted gene correlation network analysis to identify transcriptomic patterns of DNA repair pathways associated with clinical measurements of COPD severity.We found 15 genes involved in DNA repair and DNA damage tolerance to be differentially expressed in severe COPD. K-means clustering of COPD cases based on this 15-gene signature identified three patient clusters with significant differences in clinical characteristics and global transcriptomic profiles. Increasing COPD severity was associated with downregulation of the nucleotide excision repair pathway.Systematic analysis of the lung tissue transcriptome of individuals with severe COPD identified DNA repair responses associated with disease severity that may underlie COPD pathogenesis., Competing Interests: Conflict of interest: W. Timens reports unrestricted institutional grants from Merck, during the conduct of the study; fees paid to institution for consultancy from Pfizer, fees paid to the institution for lecturing from GSK, Chiesi, Lilly Oncology and Boehringer Ingelheim, fees paid to the institution for consultancy and lecturing, and travel costs, from Roche Diagnostics/Ventana, grants from Dutch Asthma Fund, fees for travel paid to the institution from Biotest, and fees paid to the institution for consultancy and lecturing from Merck Sharp Dohme, AstraZeneca and Novartis, outside the submitted work. Conflict of interest: N. Kaminski reports grants and personal fees for consultancy from Biogen Idec, personal fees for consultancy from Boehringer Ingelheim, Third Rock and MMI, non-financial support from Actelion and Miragen, personal fees for advisory board work from Pliant, unpaid consultancy work for Samumed, and personal fees from Numedii, outside the submitted work; in addition, N. Kaminski has a patent New Therapies in Pulmonary Fibrosis licensed, and a patent Peripheral Blood Gene Expression issued, and is a Member of the Scientific Advisory Committee, the Research Advisory Forum and the Board of the Pulmonary Fibrosis Foundation, and also serves as Deputy Editor of Thorax. None of the above relate to COPD., (Copyright ©ERS 2018.)

Genome-wide mRNA profiling in lung tissue from human and animal models can provide novel insights into the pathogenesis of chronic obstructive pulmonary disease (COPD). While 6 months of smoke exposure are widely used, shorter durations were also reported. The overlap of short term and long-term smoke exposure in mice is currently not well understood, and their representation of the human condition is uncertain. Lung tissue gene expression profiles of six murine smoking experiments (n = 48) were obtained from the Gene Expression Omnibus (GEO) and analyzed to identify the murine smoking signature. The "human smoking" gene signature containing 386 genes was previously published in the lung eQTL study (n = 1,111). A signature of mild COPD containing 7 genes was also identified in the same study. The lung tissue gene signature of "severe COPD" (n = 70) contained 4,071 genes and was previously published. We detected 3,723 differentially expressed genes in the 6 month-exposure mice datasets (FDR <0.1). Of those, 184 genes (representing 48% of human smoking) and 1,003 (representing 27% of human COPD) were shared with the human smoking-related genes and the COPD severity-related genes, respectively. There was 4-fold over-representation of human and murine smoking-related genes (P = 6.7 × 10 -26 ) and a 1.4 fold in the severe COPD -related genes (P = 2.3 × 10 -12 ). There was no significant enrichment of the mice and human smoking-related genes in mild COPD signature. These data suggest that murine smoke models are strongly representative of molecular processes of human smoking but less of COPD.

Background: The concept that small conducting airways less than 2 mm in diameter become the major site of airflow obstruction in chronic obstructive pulmonary disease (COPD) is well established in the scientific literature, and the last generation of small conducting airways, terminal bronchioles, are known to be destroyed in patients with very severe COPD. We aimed to determine whether destruction of the terminal and transitional bronchioles (the first generation of respiratory airways) occurs before, or in parallel with, emphysematous tissue destruction., Methods: In this cross-sectional analysis, we applied a novel multiresolution CT imaging protocol to tissue samples obtained using a systematic uniform sampling method to obtain representative unbiased samples of the whole lung or lobe of smokers with normal lung function (controls) and patients with mild COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 1), moderate COPD (GOLD 2), or very severe COPD (GOLD 4). Patients with GOLD 1 or GOLD 2 COPD and smokers with normal lung function had undergone lobectomy and pneumonectomy, and patients with GOLD 4 COPD had undergone lung transplantation. Lung tissue samples were used for stereological assessment of the number and morphology of terminal and transitional bronchioles, airspace size (mean linear intercept), and alveolar surface area., Findings: Of the 34 patients included in this study, ten were controls (smokers with normal lung function), ten patients had GOLD 1 COPD, eight had GOLD 2 COPD, and six had GOLD 4 COPD with centrilobular emphysema. The 34 lung specimens provided 262 lung samples. Compared with control smokers, the number of terminal bronchioles decreased by 40% in patients with GOLD 1 COPD (p=0·014) and 43% in patients with GOLD 2 COPD (p=0·036), the number of transitional bronchioles decreased by 56% in patients with GOLD 1 COPD (p=0·0001) and 59% in patients with GOLD 2 COPD (p=0·0001), and alveolar surface area decreased by 33% in patients with GOLD 1 COPD (p=0·019) and 45% in patients with GOLD 2 COPD (p=0·0021). These pathological changes were found to correlate with lung function decline. We also showed significant loss of terminal and transitional bronchioles in lung samples from patients with GOLD 1 or GOLD 2 COPD that had a normal alveolar surface area. Remaining small airways were found to have thickened walls and narrowed lumens, which become more obstructed with increasing COPD GOLD stage., Interpretation: These data show that small airways disease is a pathological feature in mild and moderate COPD. Importantly, this study emphasises that early intervention for disease modification might be required by patients with mild or moderate COPD., Funding: Canadian Institutes of Health Research., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Causal genes of chronic obstructive pulmonary disease (COPD) remain elusive. The current study aims at integrating genome-wide association studies (GWAS) and lung expression quantitative trait loci (eQTL) data to map COPD candidate causal genes and gain biological insights into the recently discovered COPD susceptibility loci. Two complementary genomic datasets on COPD were studied. First, the lung eQTL dataset which included whole-genome gene expression and genotyping data from 1038 individuals. Second, the largest COPD GWAS to date from the International COPD Genetics Consortium (ICGC) with 13 710 cases and 38 062 controls. Methods that integrated GWAS with eQTL signals including transcriptome-wide association study (TWAS), colocalization and Mendelian randomization-based (SMR) approaches were used to map causality genes, i.e. genes with the strongest evidence of being the functional effector at specific loci. These methods were applied at the genome-wide level and at COPD risk loci derived from the GWAS literature. Replication was performed using lung data from GTEx. We collated 129 non-overlapping risk loci for COPD from the GWAS literature. At the genome-wide scale, 12 new COPD candidate genes/loci were revealed and six replicated in GTEx including CAMK2A, DMPK, MYO15A, TNFRSF10A, BTN3A2 and TRBV30. In addition, we mapped candidate causal genes for 60 out of the 129 GWAS-nominated loci and 23 of them were replicated in GTEx. Mapping candidate causal genes in lung tissue represents an important contribution to the genetics of COPD, enriches our biological interpretation of GWAS findings, and brings us closer to clinical translation of genetic associations.

Background: Smoking is the principal modifiable environmental risk factor for chronic obstructive pulmonary disease (COPD) which affects 300 million people and is the 3rd leading cause of death worldwide. Most of the genetic studies of smoking have relied on self-reported smoking status which is vulnerable to reporting and recall bias. Using data from the Lung Health Study (LHS), we sought to identify genetic variants associated with quantitative smoking and cessation in individuals with mild to moderate COPD., Methods: The LHS is a longitudinal multicenter study of mild-to-moderate COPD subjects who were all smokers at recruitment. We performed genome-wide association studies (GWASs) for salivary cotinine (n = 4024), exhaled carbon monoxide (eCO) (n = 2854), cigarettes per day (CPD) (n = 2706) and smoking cessation at year 5 follow-up (n = 717 quitters and 2175 smokers). The GWAS analyses were adjusted for age, gender, and genetic principal components., Results: For cotinine levels, SNPs near UGT2B10 gene achieved genome-wide significance (i.e. P < 5 × 10 - 8 ) with top SNP rs10023464, P = 1.27 × 10 - 11 . For eCO levels, one significant SNP was identified which mapped to the CHRNA3 gene (rs12914385, P = 2.38 × 10 - 8 ). A borderline region mapping to KCNMA1 gene was associated with smoking cessation (rs207675, P = 5.95 × 10 - 8 ). Of the identified loci, only the CHRNA3/5 locus showed significant associations with lung function but only in heavy smokers. No regions met genome-wide significance for CPD., Conclusion: The study demonstrates that using objective measures of smoking such as eCO and/or salivary cotinine can more precisely capture the genetic contribution to multiple aspects of smoking behaviour. The KCNMA1 gene association with smoking cessation may represent a potential therapeutic target and warrants further studies., Trial Registration: The Lung Health Study ClinicalTrials.gov Identifier: NCT00000568 . Date of registration: October 28, 1999.