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Lung resistance ( RL) 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 RL, 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 RL and apparent airway resistance ( RAW, 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 RL, 80.3% of that increase was caused by an increase in RAW; the increase in apparent tissue resistance ( RT) was insignificant. 57.7% of the increase in RAW was abolished by a single DI. After subtracting RAW from RL, the remaining RT 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, RL in an unchallenged lung is mostly composed of RT, and the increase in RL due to ACh-challenge stems mostly from the increase in RAW and that both RAW and RT 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. more...

Lung resistance ( RL) and elastance ( EL) can be measured during positive or negative pressure ventilation. Whether the different modes of ventilation produce different RL and EL 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 RL and EL 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, RL and EL were significantly higher in NPV at high inflation pressures. Interestingly, diameters of smaller airways (diameters L is higher in NPV (vs. PPV), because the peripheral parenchyma is a major source of tissue resistance, which is a part of the RL that increases with pressure. This explanation is consistent with the finding that during high frequency ventilation (>1 Hz, where RL reflects airway resistance more than tissue resistance), the difference in RL between NPV and PPV disappeared. more...

PDF file - 589K, Probe sets significantly associated with smoking in the discovery set

PDF file - 242K, Table S2. Clinical characteristics of patients in the first replication set (UBC). Table S3. Clinical characteristics of patients in the second replication set (Groningen). Figure S1. Volcano plots showing the impact of smoking, COPD, and lung cancer on gene expression in the lung. Figure S2. Comparison of gene expression recovery following smoking cessation between the discovery set (Laval) and UBC. Figure S3. Comparison of gene expression recovery following smoking cessation between the discovery set (Laval) and Groningen. Figure S4. Expression of SERPIND1 in lung parenchyma of smoker and never-smoker by immunochemistry. Figure S5. Enrichment plot for slowly reversible gene in UBC. Figure S6. Enrichment plot for slowly reversible gene in Groningen more...

RATIONALE: The James Hogg Lung Registry (JHLR) was established in 1977 to enable respiratory disease research through the biobanking of human lung tissues. The objective of this report is to provid... more...

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 (FEV1/FVC%) 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, FEV1/FVC% 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 FEV1/FVC% and PIF/MEF50 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. more...

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 ( Vmax), 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 Vmax 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. more...

Rationale Sleep duration is critical to growth, learning, and immune function development in infancy. Strategies to ensure that national recommendations for sleep duration in infants are met require knowledge of perinatal factors that affect infant sleep. Objectives To investigate the mechanistic pathways linking maternal education and infant sleep. Methods An observational study was conducted on 619 infants whose mothers were enrolled at the Edmonton site of the CHILD birth cohort. Infant sleep duration at three months was assessed using the Brief Infant Sleep Questionnaire. Maternal education was collected via maternal report. Prenatal and postnatal depression scores were obtained from the 20-item Center for Epidemiologic Studies Depression Scale (CES-D). Birth records and maternal report were the source of covariate measures. Mediation analysis (PROCESS v3.0) was used to examine the indirect effects of maternal education on infant sleep duration mediated through prenatal depression and birth mode. Measurements and main results At three months of age, infants slept on average 14.1 h. Lower maternal education and prenatal depression were associated with significantly shorter infant sleep duration. Emergency cesarean section birth was associated with 1-hour shorter sleep duration at three months compared to vaginal birth [without intrapartum antibiotic prophylaxis] (β: −0.99 h; 95% CI: −1.51, −0.48). Thirty percent of the effect of lower maternal education on infant total sleep duration was mediated sequentially through prenatal depression and birth mode (Total Indirect Effects: −0.12, 95% CI: −0.22, −0.03, p Conclusions Prenatal depression and birth mode sequentially mediate the effect of maternal education on infant sleep duration. more...

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: Perfor... more...

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 cmH2O 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. more...

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 β2 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, β2 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. more...

We relate changes of the airway wall to the response of the intact airway and the whole lung. We address how mechanical conditions and specific structural changes for an airway contribute to hyperresponsiveness resistant to deep inspiration. This review conveys that the origins of hyperresponsiveness do not devolve into an abnormality at single structural level but require examination of the complex interplay of all the parts. more...

The hypothesis that the small conducting airways were the major site of obstruction to airflow in normal lungs was introduced by Rohrer in 1915 and prevailed until Weibel introduced a quantitative method of studying lung anatomy in 1963. Green repeated Rohrer's calculations using Weibels new data in 1965 and found that the smaller conducting airways offered very little resistance to airflow. This conflict was resolved by seminal experiments conducted by Macklem and Mead in 1967, which confirmed that a small proportion of the total lower airways resistance is attributable to small airways more...

Introduction Although the prevalence of chronic obstructive pulmonary disease (COPD) is similar between men and women, current evidence used to support bronchodilator therapy has been generated in therapeutic trials that have predominately enrolled male patients. Here, we determined whether there is any significant sex-related differences in FEV1 responses to ipratropium bromide. Methods Data from the Lung Health Study (n = 5887; 37% females) were used to determine changes in FEV1 with ipratropium or placebo in male and female subjects with mild to moderate COPD over 5 years. Lung Expression Quantitative Trait Loci (eQTL) dataset was used to determine whether there were any sex-related differences in gene expression for muscarinic (M2 and M3) receptors in lungs of male and female patients. Results After 4 months, ipratropium therapy increased FEV1 by 6.0% in female and 2.9% in male subjects from baseline values (p = 2.42 × 10− 16). This effect was modified by body mass index (BMI) such that the biggest improvements in FEV1 with ipratropium were observed in thin female subjects (p for BMI ∗ sex interaction = 0.044). The sex-related changes in FEV1 related to ipratropium persisted for 2 years (p = 0.0134). Female compared with male lungs had greater gene expression for M3 relative to M2 receptors (p = 6.86 × 10− 8). Conclusion Ipratropium induces a larger bronchodilator response in female than in male patients and the benefits are particularly notable in non-obese females. Female lungs have greater gene expression for the M3 muscarinic receptor relative to M2 receptors than male lungs. Female patients are thus more likely to benefit from ipratropium than male COPD patients., Highlights • Ipratropium; a muscarinic antagonist bronchodilator is more effective in female COPD patients compared to males. • The effect was modified by body mass index (BMI) such that thin female subjects respond better. • Female compared with male lungs had greater gene expression for the M3/M2 ratio of muscarinic receptors. Most evidence used to support bronchodilator therapy in COPD has been generated in therapeutic trials with predominately male patients. Here, we determined whether there are any significant sex-related differences in lung function responses to the bronchodilator ipratropium bromide. After 4 months, ipratropium therapy increased lung function in females twice as much as males. This effect was modified by body mass index (BMI) such that the biggest improvements in lung function with ipratropium were observed in thin female subjects. Female compared with male lungs had greater gene expression for ipratropium receptors. Female patients are likely to benefit more from ipratropium than male COPD patients. more...

Inhaled corticosteroids (ICS) are widely prescribed for patients with chronic obstructive pulmonary disease (COPD), yet have variable outcomes and adverse reactions, which may be genetically determined. The primary aim of the study was to identify the genetic determinants for forced expiratory volume in 1 s (FEV1) changes related to ICS therapy.In the Lung Health Study (LHS)-2, 1116 COPD patients were randomised to the ICS triamcinolone acetonide (n=559) or placebo (n=557) with spirometry performed every 6 months for 3 years. We performed a pharmacogenomic genome-wide association study for the genotype-by-ICS treatment effect on 3 years of FEV1 changes (estimated as slope) in 802 genotyped LHS-2 participants. Replication was performed in 199 COPD patients randomised to the ICS, fluticasone or placebo.A total of five loci showed genotype-by-ICS interaction at p−6; of these, single nucleotide polymorphism (SNP) rs111720447 on chromosome 7 was replicated (discovery p=4.8×10−6, replication p=5.9×10−5) with the same direction of interaction effect. ENCODE (Encyclopedia of DNA Elements) data revealed that in glucocorticoid-treated (dexamethasone) A549 alveolar cell line, glucocorticoid receptor binding sites were located near SNP rs111720447. In stratified analyses of LHS-2, genotype at SNP rs111720447 was significantly associated with rate of FEV1 decline in patients taking ICS (C allele β 56.36 mL·year−1, 95% CI 29.96–82.76 mL·year−1) and in patients who were assigned to placebo, although the relationship was weaker and in the opposite direction to that in the ICS group (C allele β −27.57 mL·year−1, 95% CI −53.27– −1.87 mL·year−1).The study uncovered genetic factors associated with FEV1 changes related to ICS in COPD patients, which may provide new insight on the potential biology of steroid responsiveness in COPD. more...

The lack of bronchodilatory response to deep inspiration in asthmatics is thought to be partially due to reduced airway distensibility [1, 2], possibly caused by an increase in airway smooth muscle (ASM) tone and stiffness [3]. Rho-kinase (ROCK) is known to play a role in regulating ASM tone [4] and ASM cytoskeletal stiffness [5]. Footnotes This manuscript has recently been accepted for publication in the European Respiratory Journal . It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article. Conflict of interest: Dr. Wang reports grants from Canadian Institutes of Health Research, grants from Natural Sciences and Engineering Research Council of Canada, grants from British Columbia Lung Association, during the conduct of the study. Conflict of interest: Dr. Chitano reports grants from Canadian Institutes of Health Research, grants from Natural Sciences and Engineering Research Council of Canada, grants from British Columbia Lung Association, during the conduct of the study. Conflict of interest: Dr. Pare reports grants from Canadian Institutes of Health Research, grants from Natural Sciences and Engineering Research Council of Canada, grants from British Columbia Lung Association, during the conduct of the study. Conflict of interest: Dr. Seow reports grants from Canadian Institutes of Health Research, grants from Natural Sciences and Engineering Research Council of Canada, grants from British Columbia Lung Association, during the conduct of the study. more...

Airway remodeling, a key feature of asthma, alters every layer of the airway wall but most strikingly the airway smooth muscle (ASM) layer. Airway remodeling in asthmatics contributes to fixed airflow obstruction and can amplify airway narrowing caused by ASM activation. Previous modeling studies have shown that the increase in ASM mass has the largest effect on increasing maximal airway narrowing. Simulated heterogeneity in the dimensions and properties of the airway wall can further amplify airway narrowing. Using measurements made on histological sections from donor lungs, we show for the first time that there is profound heterogeneity of ASM area and wall area in both nonasthmatics and asthmatics. Using a mathematical model, we found that this heterogeneity, together with changes in the mean values, contributes to an increased baseline resistance and elastance in asthmatics as well as a leftward shift in the responsiveness of the airways to a simulated agonist in both nonasthmatics and asthmatics. The ability of heterogeneous wall dimensions to shift the dose-response curve is largely due to an increased susceptibility for the small airways to close. This research confirms that heterogeneity of airway wall dimensions can contribute to exaggerated airway narrowing and provides an actual assessment of the magnitude of these effects. more...

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality worldwide(1). We performed a genetic association study in 15,256 cases and 47,936 controls, with replication of select top results (P more...

Rationale: Very little is known about airways that are too small to be visible on thoracic multidetector computed tomography but larger than the terminal bronchioles.Objectives: To examine the structure of preterminal bronchioles located one generation proximal to terminal bronchioles in centrilobular and panlobular emphysema.Methods: Preterminal bronchioles were identified by backtracking from the terminal bronchioles, and their centerlines were established along the entire length of their lumens. Multiple cross-sectional images perpendicular to the centerline were reconstructed to evaluate the bronchiolar wall and lumen, and the alveolar attachments to the outer airway walls in relation to emphysematous destruction in 28 lung samples from six patients with centrilobular emphysema, 20 lung samples from seven patients with panlobular emphysema associated with alpha-1 antitrypsin deficiency, and 47 samples from seven control (donor) lungs.Measurements and Main Results: The preterminal bronchiolar length, w... more...

BACKGROUND: Genome-wide association studies have identified numerous genetic regions that influence cross-sectional lung function. Longitudinal decline in lung function also includes a heritable component but the genetic determinants have yet to be defined.OBJECTIVES: We aimed to determine whether regions associated with cross-sectional lung function were also associated with longitudinal decline and to seek novel variants which influence decline.METHODS: We analysed genome-wide data from 4167 individuals from the Busselton Health Study cohort, who had undergone spirometry (12 695 observations across eight time points). A mixed model was fitted and weighted risk scores were calculated for the joint effect of 26 known regions on baseline and longitudinal changes in FEV1 and FEV1/FVC. Potential additional regions of interest were identified and followed up in two independent cohorts.RESULTS: The 26 regions previously associated with cross-sectional lung function jointly showed a strong effect on baseline lung function (p=4.44×10-16 for FEV1/FVC) but no effect on longitudinal decline (p=0.160 for FEV1/FVC). This was replicated in an independent cohort. 39 additional regions of interest (48 variants) were identified; these associations were not replicated in two further cohorts.CONCLUSIONS: Previously identified genetic variants jointly have a strong effect on cross-sectional lung function in adults but little or no effect on the rate of decline of lung function. It is possible that they influence COPD risk through lung development. Although no genetic variants have yet been associated with lung function decline at stringent genome-wide significance, longitudinal change in lung function is heritable suggesting that there is scope for future discoveries. more...

Chronic obstructive pulmonary disease (COPD) is characterized by reduced lung function and is the third leading cause of death globally. Through genome-wide association discovery in 48,943 individuals, selected from extremes of the lung function distribution in UK Biobank, and follow-up in 95,375 individuals, we increased the yield of independent signals for lung function from 54 to 97. A genetic risk score was associated with COPD susceptibility (odds ratio per 1 s.d. of the risk score (similar to 6 alleles) (95% confidence interval) = 1.24 (1.20-1.27), P = 5.05 x 10(-49)), and we observed a 3.7-fold difference in COPD risk between individuals in the highest and lowest genetic risk score deciles in UK Biobank. The 97 signals show enrichment in genes for development, elastic fibers and epigenetic regulation pathways. We highlight targets for drugs and compounds in development for COPD and asthma (genes in the inositol phosphate metabolism pathway and CHRM3) and describe targets for potential drug repositioning from other clinical indications. more...

Background and objective The exacerbation-prone phenotype of COPD is particularly important, as exacerbations lead to poor quality of life and disease progression. We previously found that COPD patients who lack Siglec-14, a myeloid cell protein that recognizes bacteria and triggers inflammatory responses, are less prone to exacerbation. We hypothesized that the variations in other SIGLEC genes could also influence COPD exacerbation frequency, and investigated the association between SIGLEC9 polymorphisms and the exacerbation-prone phenotype of COPD. Methods We examined whether SIGLEC9 polymorphisms affect the frequency of COPD exacerbation in 135 subjects within our study population, and also analysed the correlation between the genotypes and the severity of airflow obstruction and emphysema in 362 Japanese smokers including 244 COPD patients. The association between these single nucleotide polymorphisms (SNPs) and COPD phenotypes were also assessed in a Caucasian population of ECLIPSE study. The effects of these coding SNPs (cSNPs) on Siglec-9 protein functions were analysed using in vitro assays. Results The G allele of rs2075803 and rs2075803 G/rs2258983 A(GA) haplotype in SIGLEC9 was associated with higher frequency of exacerbations and the extent of emphysema in COPD. These results did not replicate in the ECLIPSE study. A myeloid cell line expressing the Siglec-9 variant corresponding to GA haplotype produced more TNF-α than the one expressing the variant corresponding to the other major haplotype. Conclusion The SIGLEC9 rs2075803 G/rs2258983 A haplotype, which corresponds to a Siglec-9 variant that is less effective at suppressing inflammatory response, may be a risk factor for the development of emphysema. more...

The major histocompatibility complex (MHC) has been linked with hundreds of diseases [1]. The MHC is one of the most complex regions of the human genome, because of the high gene density, extended linkage disequilibrium (LD) and sequence diversity [2]. Recent genome-wide association studies (GWAS) have identified polymorphisms located in the MHC that are associated with lung diseases and related traits: asthma, cystic fibrosis, idiopathic interstitial pneumonia, lung cancer and lung function. However, due to the limitations of GWAS and tissue-specific characteristics of gene expression [3], the causal genes and genetic mechanisms mediating the heritable risk within this locus remain to be found. more...