Genetic determinants of emphysema distribution in the national emphysema treatment trial

Therapeutic Potential of Small Molecules Targeting Oxidative Stress in the Treatment of Chronic Obstructive Pulmonary Disease (COPD): A Comprehensive Review

Chronic obstructive pulmonary disease (COPD) is an increasing and major global health problem. COPD is also the third leading cause of death worldwide. Oxidative stress (OS) takes place when various reactive species and free radicals swamp the availability of antioxidants. Reactive nitrogen species, reactive oxygen species (ROS), and their counterpart antioxidants are important for host defense and physiological signaling pathways, and the development and progression of inflammation. During the disturbance of their normal steady states, imbalances between antioxidants and oxidants might induce pathological mechanisms that can further result in many non-respiratory and respiratory diseases including COPD. ROS might be either endogenously produced in response to various infectious pathogens including fungi, viruses, or bacteria, or exogenously generated from several inhaled particulate or gaseous agents including some occupational dust, cigarette smoke (CS), and air pollutants. Therefore, targeting systemic and local OS with therapeutic agents such as small molecules that can increase endogenous antioxidants or regulate the redox/antioxidants system can be an effective approach in treating COPD. Various thiol-based antioxidants including fudosteine, erdosteine, carbocysteine, and N-acetyl-L-cysteine have the capacity to increase thiol content in the lungs. Many synthetic molecules including inhibitors/blockers of protein carbonylation and lipid peroxidation, catalytic antioxidants including superoxide dismutase mimetics, and spin trapping agents can effectively modulate CS-induced OS and its resulting cellular alterations. Several clinical and pre-clinical studies have demonstrated that these antioxidants have the capacity to decrease OS and affect the expressions of several pro-inflammatory genes and genes that are involved with redox and glutathione biosynthesis. In this article, we have summarized the role of OS in COPD pathogenesis. Furthermore, we have particularly focused on the therapeutic potential of numerous chemicals, particularly antioxidants in the treatment of COPD.

Dynamic Quantitative Magnetic Resonance Imaging Assessment of Areas of the Lung During Free-Breathing of Patients with Chronic Obstructive Pulmonary Disease

RATIONALE AND OBJECTIVES

Changes in the geometry of the chest wall due to lung hyperinflation occur in COPD. However, the quantitative assessment of impaired lung motions and its association with the clinical characteristics of COPD patients are unclear. This study aimed to investigate the respiratory kinetics of COPD patients by dynamic MRI.

MATERIALS AND METHODS

This study enrolled 22 COPD patients and 10 normal participants who underwent dynamic MRI and pulmonary function testing (PFT). Changes in the areas of the lung and mediastinum during respiration were compared between the COPD patients and the normal controls. Relationships between MRI, CT parameters, and clinical measures that included PFT results also were evaluated.

RESULTS

Asynchronous movements and decreased diaphragmatic motion were found in COPD patients. COPD patients had a larger ratio of MRI-measured lung areas at expiration to inspiration, a smaller magnitude of the peak area change ratio, and a smaller mediastinal-thoracic area ratio than the normal participants. The lung area ratio was associated with FEV₁/FVC, predicted RV%, and CT lung volume/predicted total lung capacity (pTLC). The lung area ratio of the right lower and left lower lungs was significantly correlated with emphysema of each lower lobe. The expiratory mediastinal-thoracic area ratio was associated with FEV₁% predicted and RV/TLC.

CONCLUSION

Changes in the lung areas of COPD patients as shown on MRI reflected the severity of airflow limitation, hyperinflation, and the extent of emphysema. Dynamic MRI provides essential information about respiratory kinetics in COPD.

Progress and Research Priorities in Imaging Genomics for Heart and Lung Disease: Summary of an NHLBI Workshop

Imaging genomics is a rapidly evolving field that combines state-of-the-art bioimaging with genomic information to resolve phenotypic heterogeneity associated with genomic variation, improve risk prediction, discover prevention approaches, and enable precision diagnosis and treatment. Contemporary bioimaging methods provide exceptional resolution generating discrete and quantitative high-dimensional phenotypes for genomics investigation. Despite substantial progress in combining high-dimensional bioimaging and genomic data, methods for imaging genomics are evolving. Recognizing the potential impact of imaging genomics on the study of heart and lung disease, the National Heart, Lung, and Blood Institute convened a workshop to review cutting-edge approaches and methodologies in imaging genomics studies, and to establish research priorities for future investigation. This report summarizes the presentations and discussions at the workshop. In particular, we highlight the need for increased availability of imaging genomics data in diverse populations, dedicated focus on less common conditions, and centralization of efforts around specific disease areas.

Imbalance Between Injury and Defense in the COPD Emphysematous Phenotype

The chronic obstructive pulmonary disease (COPD) emphysematous phenotype is characterized by destruction of lung tissue structure. Patients with this phenotype usually present with typical emphysema-like changes on chest computed Tomography CT, experience higher mortality and poorer prognosis, and are insensitive to routine pharmacological COPD therapy. However, the pathogenesis for the COPD emphysematous phenotype remains unclear, resulting in diagnostic and therapeutic challenges. The imbalance between injury and defense mechanisms is essential in the progression of many pulmonary diseases. Thus, in this review, we focus on the pathogenesis of the COPD emphysematous phenotype and discuss the pathophysiological processes involved in disease progression, from the perspective of injury and defense imbalance.

High prevalence of airway obstruction and pulmonary emphysema in urothelial (renal pelvis, ureter, and bladder) cancer patients

BACKGROUND

Cigarette smoking is a major cause of COPD, with patients also presenting complications that stem from other smoking-related diseases, including urothelial cancer. However, the prevalence of COPD or airflow obstruction in urothelial cancer patients has not been well studied.

METHODS

We investigated the prevalence of airflow obstruction (FEV1/FVC < 70%) in newly diagnosed urothelial cancer patients and identified the risk factors for airflow obstruction in existing urothelial cancer patients. Additionally, we compared the characteristics of subjects who had been diagnosed with both airflow obstruction and urothelial cancer, and subjects whose airflow obstruction was discovered during health screenings.

RESULTS

A total of 217 patients were newly diagnosed with urothelial cancer during the study period at our institution. Among all patients, 210 (96.8%) underwent an evaluable lung function test, in which 38.6% (81 patients) displayed airflow obstruction defined as FEV1/FVC < 70%. In urothelial cancer patients, age, smoking index (pack-years), and BMI proved to be significant risk factors for airflow obstruction in multivariate logistic regression (p = 0.007, p < 0.0001, and p = 0.035, respectively). Gender, cancer stage, and cancer location were not significant risk factors. Patients with both airflow obstruction and urothelial cancer showed a more advanced emphysematous change than subjects presenting with airflow obstruction alone (unpaired t-test, p = 0.0003).

CONCLUSIONS

Airflow obstruction was identified in 38.6% of urothelial cancer patients. Age, smoking index (pack-years), and BMI were significant risk factors. A significantly higher emphysematous score was observed in subjects with urothelial cancer than in subjects with airway obstruction alone.

Influence of Emphysema and Air Trapping Heterogeneity on Pulmonary Function in Patients with COPD

Purpose

To explore the influence of emphysema and air trapping heterogeneity on pulmonary function changes in patients with stable chronic obstructive pulmonary disease (COPD).

Patients and methods

One hundred and seventy-nine patients with stable COPD were enrolled in this prospective study. All patients underwent low-dose inspiratory and expiratory CT scanning and pulmonary-function tests. CT quantitative data for the emphysema index (EI) on full-inspiration and air trapping (AT) on full-expiration were measured for the whole lung, the right and left lungs, and the cranial-caudal lung zones. The heterogeneity index (HI) values for emphysema and air trapping were determined as the ratio of the difference to the sum of the respective indexes. The cranial-caudal HI and left–right lung HI were compared between mild-to-moderate (GOLD stage I and II) and severe (GOLD stage III and IV) disease groups. The associations between HI and pulmonary-function measurements adjusted for age, sex, height, smoking history, EI and AT of the total lung were assessed using multiple linear regression analysis.

Results

The absolute values for cranial-caudal HI (AT_CC_HI) and left–right lung HI (AT_LR_HI) on full-expiration were significantly larger in the mild-to-moderate group, while no significant intergroup differences were observed on full-inspiration. COPD patients with lower-zone and/or left-lung predominance showed significantly lower pulmonary function than those with upper-zone and/or right-lung predominance on full-expiration, whereas no significant differences were observed on full-inspiration. The absolute values of AT_CC_HI and AT_LR_HI significantly correlated with pulmonary-function measurements. Higher AT_CC_HI and lower AT_LR_HI absolute values indicated better pulmonary function, after adjusting for age, sex, height, smoking history, EI and AT of the total lung.

Conclusion

Subjects with more heterogeneous distribution and/or upper-zone predominant and/or right-lung predominant patterns on full-expiration tend to have better pulmonary function. Thus, in comparison with emphysema heterogeneity, AT heterogeneity better reflects the pulmonary function changes in COPD patients.

Celebration of the 50-Year Anniversary of the National Heart, Lung, and Blood Institute Division of Lung Diseases: A Half-Century of Landmark Clinical Trials

The National Institutes of Health (NIH)-National Heart, Lung, and Blood Institute's (NHLBI) Division of Lung Diseases is celebrating its 50th anniversary. On this occasion, we are reviewing the major landmark clinical trials that were initiated by the NHLBI's Division of Lung Disease and that have had substantial impact on our understanding of chronic obstructive pulmonary disease (COPD) and how it is best treated. Although some of these trials did not show hypothesized treatment benefits for COPD, they have enabled clinicians to provide care for individuals with COPD relying on the most rigorous evidence. The 5 trials that are reviewed here are: the Intermittent Positive Pressure Breathing Trial, the Nocturnal Oxygen Treatment Trial, the Lung Health Study, the National Emphysema Treatment Trial, and the Long-term Oxygen Treatment Trial. These clinical trials have not only set the standards for COPD care but have served as models for the state-of-the-art conduct of clinical research in COPD.

Early-onset emphysema in a large French-Canadian family: a genetic investigation

BACKGROUND

Inherited mutations in SERPINA1 coding for the alpha-1 antitrypsin (A1AT) protein is the only well established cause of hereditary emphysema. We aimed to identify the genetic ecause of early-onset emphysema in a five-generation French-Canadian family free of A1AT deficiency.

METHODS

Between Dec 1, 2014, and April 1, 2017, we investigated 63 individuals from a single pedigree, including 55 with DNA available. Whole-exome sequencing was done in a convenience sample of 14 individuals (nine with unambiguous expression of the typical form of emphysema observed in this family). We filtered rare non-synonymous variants that were predicted to be damaging to identify a single mutation in a biologically relevant gene shared among all affected individuals. We assessed segregation with the disease in additional family members who were not evaluated by whole-exome sequencing. The effect of the candidate variant on protein function was evaluated in vitro. mRNA and protein expression of the candidate gene was assessed in lung samples from unrelated individuals (n=80) with and without emphysema who underwent surgery for lung cancer at our institution.

FINDINGS

A rare in-silico-predicted damaging variant (Ala455Thr) was identified in the protein tyrosine phosphatase non-receptor type 6 (PTPN6) gene, also known as SHP-1, an important negative regulator of immune processes. 20 (95%) of 21 family members with computed tomography-confirmed emphysema were heterozygotes for the Ala455Thr mutation. No Thr455 homozygotes were identified. Emphysema or reduced diffusion capacity was observed in all heterozygotes with a history of smoking. Incomplete penetrance of the mutation and variable degrees of emphysema were observed in never smokers. The Ala455Thr mutation in SHP-1 caused a reduction in phosphatase activity in vitro, confirming the loss-of-function effect of the mutation. mRNA and protein expression of PTPN6 were upregulated in smokers, but were not associated with emphysema or severity of airflow limitation.

INTERPRETATION

An inherited variant in the gene PTPN6 is responsible for early-onset emphysema in this family. To our knowledge, this is the second form of hereditary emphysema since the discovery of A1AT deficiency in the 1960s, representing a breakthrough in understanding the genetics and pathogenesis of emphysema.

FUNDING

Fonds sur les maladies respiratoires J.-D. Bégin-P.-H. Lavoie de l'Université Laval, Fondation de l'Institut universitaire de cardiologie et de pneumologie de Québec, CIHR/GSK research Chair on COPD at Université Laval, and the Canadian Institutes of Health Research.

Reduced transient receptor potential vanilloid 2 expression in alveolar macrophages causes COPD in mice through impaired phagocytic activity

Background

Defective phagocytosis in alveolar macrophages is associated with chronic obstructive pulmonary disease (COPD). Transient receptor potential cation channel subfamily V member 2 (TRPV2), a type of nonselective cation channel pertinent to diverse physiological functions, regulates macrophage phagocytosis. However, the role of TRPV2 in COPD remains poorly understood. Here, we explored the role of TRPV2 in the development of COPD.

Methods

Macrophage TRPV2 expression and phagocytosis function were measured in MH-S cells (a murine alveolar macrophage cell line) and a cigarette smoke exposure mouse model.

Results

TRPV2 expression and phagocytosis function were reduced when MH-S cells were exposed to cigarette smoke extract (CSE). TRPV2 knockdown by siRNA decreased phagocytosis in MH-S cells. Consistently, TRPV2 expression was reduced in alveolar macrophages prepared from bronchoalveolar lavage samples of mice which were exposed to cigarette smoke for 2 months. In addition, the alveolar space was progressively enlarged during development in TRPV2 knockout (TRPV2KO) mice. Moreover, exposure to cigarette smoke for 2 months significantly induced alveolar space enlargement in TRPV2KO mice, but not in wild-type (WT) mice. The phagocytic function of alveolar macrophages from TRPV2KO mice was reduced, compared with macrophages from WT mice.

Conclusions

TRPV2 expression is profoundly downregulated in alveolar macrophages at early time points of cigarette smoke exposure. Reduced TRPV2-mediated phagocytic function renders the lung susceptible to cigarette smoke-induced alveolar space enlargement. TRPV2 may provide a therapeutic target for COPD induced by cigarette smoke.

Electronic supplementary material

The online version of this article (10.1186/s12890-019-0821-y) contains supplementary material, which is available to authorized users.

Reprint of: Voxel-Wise Longitudinal Parametric Response Mapping Analysis of Chest Computed Tomography in Smokers

RATIONALE AND OBJECTIVES

Chronic obstructive pulmonary disease is a heterogeneous disease characterized by small airway abnormality and emphysema. We hypothesized that a voxel-wise computed tomography analytic approach would identify patterns of disease progression in smokers.

MATERIALS AND METHODS

We analyzed 725 smokers in spirometric GOLD stages 0-4 with two chest CTs 5 years apart. Baseline inspiration, follow-up inspiration and follow-up expiration images were spatially registered to baseline expiration so that each voxel had correspondences across all time points and respiratory phases. Voxel-wise Parametric Response Mapping (PRM) was then generated for the baseline and follow-up scans. PRM classifies lung as normal, functional small airway disease (PRM^fSAD), and emphysema (PRM^EMPH).

RESULTS

Subjects with low baseline PRM^fSAD and PRM^EMPH predominantly had an increase in PRM^fSAD on follow-up; those with higher baseline PRM^fSAD and PRM^EMPH mostly had increases in PRM^EMPH. For GOLD 0 participants (n = 419), mean 5-year increases in PRM^fSAD and PRM^EMPH were 0.3% for both; for GOLD 1-4 participants (n = 306), they were 0.6% and 1.6%, respectively. Eighty GOLD 0 subjects (19.1%) had overall radiologic progression (30.0% to PRM^fSAD, 52.5% to PRM^EMPH, and 17.5% to both); 153 GOLD 1-4 subjects (50.0%) experienced progression (17.6% to PRM^fSAD, 48.4% to PRM^EMPH, and 34.0% to both). In a multivariable model, both baseline PRM^fSAD and PRM^EMPH were associated with development of PRM^EMPH on follow-up, although this relationship was diminished at higher levels of baseline PRM^EMPH.

CONCLUSION

A voxel-wise longitudinal PRM analytic approach can identify patterns of disease progression in smokers with and without chronic obstructive pulmonary disease.

Voxel-Wise Longitudinal Parametric Response Mapping Analysis of Chest Computed Tomography in Smokers

RATIONALE AND OBJECTIVES

Chronic obstructive pulmonary disease is a heterogeneous disease characterized by small airway abnormality and emphysema. We hypothesized that a voxel-wise computed tomography analytic approach would identify patterns of disease progression in smokers.

MATERIALS AND METHODS

We analyzed 725 smokers in spirometric GOLD stages 0-4 with two chest CTs 5 years apart. Baseline inspiration, follow-up inspiration and follow-up expiration images were spatially registered to baseline expiration so that each voxel had correspondences across all time points and respiratory phases. Voxel-wise Parametric Response Mapping (PRM) was then generated for the baseline and follow-up scans. PRM classifies lung as normal, functional small airway disease (PRMfSAD), and emphysema (PRMEMPH).

RESULTS

Subjects with low baseline PRMfSAD and PRMEMPH predominantly had an increase in PRMfSAD on follow-up; those with higher baseline PRMfSAD and PRMEMPH mostly had increases in PRMEMPH. For GOLD 0 participants (n = 419), mean 5-year increases in PRMfSAD and PRMEMPH were 0.3% for both; for GOLD 1-4 participants (n = 306), they were 0.6% and 1.6%, respectively. Eighty GOLD 0 subjects (19.1%) had overall radiologic progression (30.0% to PRMfSAD, 52.5% to PRMEMPH, and 17.5% to both); 153 GOLD 1-4 subjects (50.0%) experienced progression (17.6% to PRMfSAD, 48.4% to PRMEMPH, and 34.0% to both). In a multivariable model, both baseline PRMfSAD and PRMEMPH were associated with development of PRMEMPH on follow-up, although this relationship was diminished at higher levels of baseline PRMEMPH.

CONCLUSION

A voxel-wise longitudinal PRM analytic approach can identify patterns of disease progression in smokers with and without chronic obstructive pulmonary disease.

RNA sequencing identifies common pathways between cigarette smoke exposure and replicative senescence in human airway epithelia

BACKGROUND

Aging is affected by genetic and environmental factors, and cigarette smoking is strongly associated with accumulation of senescent cells. In this study, we wanted to identify genes that may potentially be beneficial for cell survival in response to cigarette smoke and thereby may contribute to development of cellular senescence.

RESULTS

Primary human bronchial epithelial cells from five healthy donors were cultured, treated with or without 1.5% cigarette smoke extract (CSE) for 24 h or were passaged into replicative senescence. Transcriptome changes were monitored using RNA-seq in CSE and non-CSE exposed cells and those passaged into replicative senescence. We found that, among 1534 genes differentially regulated during senescence and 599 after CSE exposure, 243 were altered in both conditions, representing strong enrichment. Pathways and gene sets overrepresented in both conditions belonged to cellular processes that regulate reactive oxygen species, proteasome degradation, and NF-κB signaling.

CONCLUSIONS

Our results offer insights into gene expression responses during cellular aging and cigarette smoke exposure, and identify potential molecular pathways that are altered by cigarette smoke and may also promote airway epithelial cell senescence.

Lobar Emphysema Distribution Is Associated With 5-Year Radiological Disease Progression

BACKGROUND

Emphysema has considerable variability in its regional distribution. Craniocaudal emphysema distribution is an important predictor of the response to lung volume reduction. However, there is little consensus regarding how to define upper lobe-predominant and lower lobe-predominant emphysema subtypes. Consequently, the clinical and genetic associations with these subtypes are poorly characterized.

METHODS

We sought to identify subgroups characterized by upper-lobe or lower-lobe emphysema predominance and comparable amounts of total emphysema by analyzing data from 9,210 smokers without alpha-1-antitrypsin deficiency in the Genetic Epidemiology of COPD (COPDGene) cohort. CT densitometric emphysema was measured in each lung lobe. Random forest clustering was applied to lobar emphysema variables after regressing out the effects of total emphysema. Clusters were tested for association with clinical and imaging outcomes at baseline and at 5-year follow-up. Their associations with genetic variants were also compared.

RESULTS

Three clusters were identified: minimal emphysema (n = 1,312), upper lobe-predominant emphysema (n = 905), and lower lobe-predominant emphysema (n = 796). Despite a similar amount of total emphysema, the lower-lobe group had more severe airflow obstruction at baseline and higher rates of metabolic syndrome compared with subjects with upper-lobe predominance. The group with upper-lobe predominance had greater 5-year progression of emphysema, gas trapping, and dyspnea. Differential associations with known COPD genetic risk variants were noted.

CONCLUSIONS

Subgroups of smokers defined by upper-lobe or lower-lobe emphysema predominance exhibit different functional and radiological disease progression rates, and the upper-lobe predominant subtype shows evidence of association with known COPD genetic risk variants. These subgroups may be useful in the development of personalized treatments for COPD.

Genome-Wide Association Study of the Genetic Determinants of Emphysema Distribution

RATIONALE

Emphysema has considerable variability in the severity and distribution of parenchymal destruction throughout the lungs. Upper lobe-predominant emphysema has emerged as an important predictor of response to lung volume reduction surgery. Yet, aside from alpha-1 antitrypsin deficiency, the genetic determinants of emphysema distribution remain largely unknown.

OBJECTIVES

To identify the genetic influences of emphysema distribution in non-alpha-1 antitrypsin-deficient smokers.

METHODS

A total of 11,532 subjects with complete genotype and computed tomography densitometry data in the COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease [COPD]; non-Hispanic white and African American), ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints), and GenKOLS (Genetics of Chronic Obstructive Lung Disease) studies were analyzed. Two computed tomography scan emphysema distribution measures (difference between upper-third and lower-third emphysema; ratio of upper-third to lower-third emphysema) were tested for genetic associations in all study subjects. Separate analyses in each study population were followed by a fixed effect metaanalysis. Single-nucleotide polymorphism-, gene-, and pathway-based approaches were used. In silico functional evaluation was also performed.

MEASUREMENTS AND MAIN RESULTS

We identified five loci associated with emphysema distribution at genome-wide significance. These loci included two previously reported associations with COPD susceptibility (4q31 near HHIP and 15q25 near CHRNA5) and three new associations near SOWAHB, TRAPPC9, and KIAA1462. Gene set analysis and in silico functional evaluation revealed pathways and cell types that may potentially contribute to the pathogenesis of emphysema distribution.

CONCLUSIONS

This multicohort genome-wide association study identified new genomic loci associated with differential emphysematous destruction throughout the lungs. These findings may point to new biologic pathways on which to expand diagnostic and therapeutic approaches in chronic obstructive pulmonary disease. Clinical trial registered with www.clinicaltrials.gov (NCT 00608764).

Genetic polymorphism in matrix metalloproteinase-9 and transforming growth factor-β1 and susceptibility to combined pulmonary fibrosis and emphysema in a Chinese population

In this study, we aimed to explore the association of genetic polymorphism in matrix metalloproteinase-9 (MMP-9) and transforming growth factor-β1 (TGF-β1) and the susceptibility to combined pulmonary fibrosis and emphysema (CPFE). We examined the polymorphisms of the MMP-9 C-1562T and TGF-β1 T869C in 38 CPFE patients, 50 pulmonary emphysema patients, and 34 idiopathic pulmonary fibrosis (IPF) patients. The frequencies of polymorphic genotypes in MMP-9 were 78.95% CC and 21.05% CT in CPFE group, 76.0% CC and 24.0% CT in emphysema group, and 100.0% CC in IPF group. There were highly statistically significant increased frequencies of the CT genotype and T allele in CPFE and emphysema groups compared with IPF group (p < 0.05). The frequencies of polymorphic genotypes in TGF-β1 were 2.63% CC, 28.95% CT, 68.42% TT in CPFE group, 4.00% CC, 16.00% CT, 80.00% TT in emphysema group, and 5.88% CC, 41.18% CT, 52.94% TT in IPF group. Significant increases in the TT genotype and T allele frequencies were observed in emphysema group compared with IPF group (p < 0.05). Our study has showed that T allele in MMP-9 (C-1562T) and T allele in TGF-β1 (T869C) are risk factors of pulmonary emphysema. The T allele in MMP-9 (C-1562T) possibly predisposes patients with pulmonary fibrosis to develop emphysema.

Regional Emphysema of a Non-Small Cell Tumor Is Associated with Larger Tumors and Decreased Survival Rates

RATIONALE

Chronic obstructive pulmonary disease is associated with a worse overall survival in non-small cell lung cancer. Lung emphysema is one component of chronic obstructive pulmonary disease. We hypothesized that emphysema of the tumor region may result in larger tumors and a poorer overall survival.

METHODS

We evaluated 304 cases of non-small cell lung cancer from a prospectively enrolled cohort. The lung was divided into equal volumetric thirds (upper, middle, or lower region). Emphysema was defined as percentage of low-attenuation areas less than -950 Hounsfield units (%LAA-950) and measured for each region. Whole-lung %LAA-950 was defined as the emphysema score of the entire lung parenchyma, whereas regional %LAA-950 was the score within that particular region (upper, middle, or lower). The emphysema score of the region in which the tumor occurred was defined as the tumor %LAA-950. Tumor diameter was measured while blinded to characteristics of the lung parenchyma. A proportional hazards model was used to control for multiple factors associated with survival.

MEASUREMENTS AND MAIN RESULTS

Increasing tumor %LAA-950 was associated with larger tumors (P = 0.024). Survival, stratified by stage, was significantly worse in those with tumor %LAA-950 greater than or equal to the 50th percentile versus less than the 50th percentile (P = 0.046). Whole-lung %LAA-950 and regional %LAA-950 (e.g., regional emphysema without tumor occurring in the region) were not significantly associated with survival. There were no differences in presenting symptoms or locations of mediastinal or distant metastasis by emphysema score. Increasing tumor %LAA-950 was associated with an increased risk of death (adjusted hazard ratio, 1.36; confidence interval, 1.09-1.68; P = 0.006) after adjustment for age, sex, smoking status, histology, stage, performance status, chemotherapy, radiation, and surgery. Sensitivity analyses revealed no significant difference in the effect size or test of significance for each of the following conditions: (1) exclusion of cases with central tumor location, (2) exclusion of cases where surgery was performed, (3) exclusion of cases where radiation therapy was performed, (4) exclusion of cases where epidermal growth factor receptor tyrosine kinase inhibitors were administered, and (5) inclusion of only stage IV disease.

CONCLUSIONS

Increasing emphysema of the region in which a non-small cell lung cancer tumor occurs is associated with increasing tumor size and worse overall survival.

A bioinformatics strategy for detecting the complexity of Chronic Obstructive Pulmonary Disease in Northern Chinese Han Population

Chronic Obstructive Pulmonary Disease (COPD) is a complex human disease which is driven not only by genetic factors, but also by various environmental variables, such as gender, age and smoking. Therefore, there is a demand for investigating the complexity among various risk factors involved in COPD. In this study, 44 tagging SNPs from EPHX1, GSTP1, SERPINE2 and TGFB1 were selected and genotyped in 310 COPD cases and 203 controls, all of which belong to the Han from North China. We integrated functional prediction algorithms of nonsynonymous SNPs (nsSNPs) into Bayesian network to explore the complex regulatory relationships among disease traits and various risk factors. The results showed that three basic variables (age, sex and smoking) were risk factors of COPD-related trait and phenotype. Besides these environmental risk factors, deleterious nsSNPs were found to perform better than those of significant synonymous SNPs when used as variables to make risk prediction of disease outcome. This study provides further evidences for detecting the complexity of COPD in Northern Chinese Han Population.

Clinically relevant subgroups in COPD and asthma

As knowledge of airways disease has grown, it has become apparent that neither chronic obstructive pulmonary disease (COPD) nor asthma is a simple, easily defined disease. In the past, treatment options for both diseases were limited; thus, there was less need to define subgroups. As treatment options have grown, so has our need to predict who will respond to new drugs. To date, identifying subgroups has been largely reported by detailed clinical characterisation or differences in pathobiology. These subgroups are commonly called "phenotypes"; however, the problem of defining what constitutes a phenotype, whether this should include comorbid diseases and how to handle changes over time has led to the term being used loosely. In this review, we describe subgroups of COPD and asthma patients whose clinical characteristics we believe have therapeutic or major prognostic implications specific to the lung, and whether these subgroups are constant over time. Finally, we will discuss whether the subgroups we describe are common to both asthma and COPD, and give some examples of how treatment might be tailored in patients where the subgroup is clear, but the label of asthma or COPD is not.

A Genome-Wide Association Study of Emphysema and Airway Quantitative Imaging Phenotypes

RATIONALE

Chronic obstructive pulmonary disease (COPD) is defined by the presence of airflow limitation on spirometry, yet subjects with COPD can have marked differences in computed tomography imaging. These differences may be driven by genetic factors. We hypothesized that a genome-wide association study (GWAS) of quantitative imaging would identify loci not previously identified in analyses of COPD or spirometry. In addition, we sought to determine whether previously described genome-wide significant COPD and spirometric loci were associated with emphysema or airway phenotypes.

OBJECTIVES

To identify genetic determinants of quantitative imaging phenotypes.

METHODS

We performed a GWAS on two quantitative emphysema and two quantitative airway imaging phenotypes in the COPDGene (non-Hispanic white and African American), ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints), NETT (National Emphysema Treatment Trial), and GenKOLS (Genetics of COPD, Norway) studies and on percentage gas trapping in COPDGene. We also examined specific loci reported as genome-wide significant for spirometric phenotypes related to airflow limitation or COPD.

MEASUREMENTS AND MAIN RESULTS

The total sample size across all cohorts was 12,031, of whom 9,338 were from COPDGene. We identified five loci associated with emphysema-related phenotypes, one with airway-related phenotypes, and two with gas trapping. These loci included previously reported associations, including the HHIP, 15q25, and AGER loci, as well as novel associations near SERPINA10 and DLC1. All previously reported COPD and a significant number of spirometric GWAS loci were at least nominally (P < 0.05) associated with either emphysema or airway phenotypes.

CONCLUSIONS

Genome-wide analysis may identify novel risk factors for quantitative imaging characteristics in COPD and also identify imaging features associated with previously identified lung function loci.

Impact of emphysema heterogeneity on pulmonary function

Objectives

To investigate the association between emphysema heterogeneity in spatial distribution, pulmonary function and disease severity.

Methods and Materials

We ascertained a dataset of anonymized Computed Tomography (CT) examinations acquired on 565 participants in a COPD study. Subjects with chronic bronchitis (CB) and/or bronchodilator response were excluded resulting in 190 cases without COPD and 160 cases with COPD. Low attenuations areas (LAAs) (≤950 Hounsfield Unit (HU)) were identified and quantified at the level of individual lobes. Emphysema heterogeneity was defined in a manner that ranged in value from −100% to 100%. The association between emphysema heterogeneity and pulmonary function measures (e.g., FEV1% predicted, RV/TLC, and DLco% predicted) adjusted for age, sex, and smoking history (pack-years) was assessed using multiple linear regression analysis.

Results

The majority (128/160) of the subjects with COPD had a heterogeneity greater than zero. After adjusting for age, gender, smoking history, and extent of emphysema, heterogeneity in depicted disease in upper lobe dominant cases was positively associated with pulmonary function measures, such as FEV1 Predicted (p<.001) and FEV1/FVC (p<.001), as well as disease severity (p<0.05). We found a negative association between HI% , RV/TLC (p<0.001), and DLco% (albeit not a statistically significant one, p = 0.06) in this group of patients.

Conclusion

Subjects with more homogeneous distribution of emphysema and/or lower lung dominant emphysema tend to have worse pulmonary function.

Expression of matrix metalloproteinase-1 in alveolar macrophages, type II pneumocytes, and airways in smokers: relationship to lung function and emphysema

Background

An imbalance between proteolytic enzymes and their inhibitors is thought to be involved in the pathogenesis of chronic obstructive pulmonary disease. Matrix metalloproteinase-1, also known as interstitial collagenase, has been implicated as a potentially important proteinase in the genesis of chronic obstructive pulmonary disease and, more specifically, emphysema.

Methods

We performed quantitative immunohistochemical assessment of matrix metalloproteinase-1 expression in the resected lung of 20 smokers/ex-smokers who had varying severity of airflow obstruction and emphysema and compared this with the lungs of 5 nonsmokers. Emphysema was measured using a morphometric measure of the lungs’ surface area/volume ratio and with qualitative and quantitative computed tomography (CT) measures of emphysema.

Results

There were significantly more matrix metalloproteinase-1-expressing alveolar macrophages and type II pneumocytes as well as a greater percentage of small airways that stained positively for matrix metalloproteinase-1 in the lungs of smokers than in those of nonsmokers (p < 0.0001, p < 0.0001, and p = 0.0003, respectively). The extent of staining of type II pneumocytes and airways for matrix metalloproteinase-1 was significantly related to the extent of smoking (p = 0.012 and p = 0.013, respectively). In addition, the extent of matrix metalloproteinase-1 staining of alveolar macrophages was related to the lung surface area/volume ratio and to qualitative estimates of emphysema on CT.

Conclusion

These findings suggest that cigarette smoking increases expression of matrix metalloproteinase-1 in alveolar macrophages as well as in alveolar and small airway epithelial cells. Smokers who develop emphysema have increased alveolar macrophage expression of matrix metalloproteinase-1.

Electronic supplementary material

The online version of this article (doi:10.1007/s00408-014-9585-6) contains supplementary material, which is available to authorized users.

Invasive adenocarcinoma of the lung is associated with the upper lung regions

OBJECTIVES

We postulated that ventilation-perfusion (V/Q) relationships within the lung might influence where lung cancer occurs. To address this hypothesis we evaluated the location of lung adenocarcinoma, by both tumor lobe and superior-inferior regional distribution, and associated variables such as emphysema.

MATERIALS AND METHODS

One hundred fifty-nine cases of invasive adenocarcinoma and adenocarcinoma with lepidic features were visually evaluated to identify lobar or regional tumor location. Regions were determined by automated division of the lungs into three equal volumes: (upper region, middle region, or lower region). Automated densitometry was used to measure radiographic emphysema.

RESULTS

The majority of invasive adenocarcinomas occurred in the upper lobes (69%), with 94% of upper lobe adenocarcinomas occurring in the upper region of the lung. The distribution of adenocarcinoma, when classified as upper or lower lobe, was not different between invasive adenocarcinoma and adenocarcinoma with lepidic features (formerly bronchioloalveolar cell carcinoma, P = 0.08). Regional distribution of tumor was significantly different between invasive adenocarcinoma and adenocarcinoma with lepidic features (P = 0.001). Logistic regression analysis with the outcome of invasive adenocarcinoma histology was used to adjust for confounders. Tumor region continued to be a significant predictor (OR 8.5, P = 0.008, compared to lower region), whereas lobar location of tumor was not (P = 0.09). In stratified analysis, smoking was not associated with region of invasive adenocarcinoma occurrence (P = 0.089). There was no difference in total emphysema scores between invasive adenocarcinoma cases occurring in each of the three regions (P = 0.155). There was also no difference in the distribution of region of adenocarcinoma occurrence between quartiles of emphysema (P = 0.217).

CONCLUSION

Invasive adenocarcinoma of the lung is highly associated with the upper lung regions. This association is not related to smoking, history of COPD, or total emphysema. The regional distribution of invasive adenocarcinoma may be due to V/Q relationships or other local factors.

APOM and high-density lipoprotein cholesterol are associated with lung function and per cent emphysema

Chronic obstructive pulmonary disease (COPD) is linked to cardiovascular disease; however, there are few studies on the associations of cardiovascular genes with COPD. We assessed the association of lung function with 2100 genes selected for cardiovascular diseases among 20 077 European-Americans and 6900 African-Americans. We performed replication of significant loci in the other racial group and an independent consortium of Europeans, tested the associations of significant loci with per cent emphysema and examined gene expression in an independent sample. We then tested the association of a related lipid biomarker with forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio and per cent emphysema. We identified one new polymorphism for FEV1/FVC (rs805301) in European-Americans (p=1.3×10(-6)) and a second (rs707974) in the combined European-American and African-American analysis (p=1.38×10(-7)). Both single-nucleotide polymorphisms (SNPs) flank the gene for apolipoprotein M (APOM), a component of high-density lipoprotein (HDL) cholesterol. Both were replicated in an independent cohort. SNPs in a second gene related to apolipoprotein M and HDL, PCSK9, were associated with FEV1/FVC ratio among African-Americans. rs707974 was associated with per cent emphysema among European-Americans and African-Americans and APOM expression was related to FEV1/FVC ratio and per cent emphysema. Higher HDL levels were associated with lower FEV1/FVC ratio and greater per cent emphysema. These findings suggest a novel role for the apolipoprotein M/HDL pathway in the pathogenesis of COPD and emphysema.

Genetic susceptibility

Why only 20% of smokers develop clinically relevant chronic obstructive pulmonary disease (COPD) was a puzzle for many years. Now, epidemiologic studies point clearly toward a large heritable component. The combination of genome-wide association studies and candidate gene analysis is helping to identify those genetic variants responsible for an individual's susceptibility to developing COPD. In this review, the current data implicating specific loci and genes in the pathogenesis of COPD are examined.

Role of chronic obstructive pulmonary disease in lung cancer pathogenesis

Chronic obstructive pulmonary disease (COPD) and lung cancer are two important smoking related conditions. However, COPD has been shown to be an independent risk factor for lung cancer regardless of smoking history, suggesting that COPD and lung cancer may share a common pathogenesis. This review summarizes the epidemiology of lung cancer and COPD briefly, as well as discussing the potential for shared genetic risk, and shared genomic mechanisms, such as epigenetic changes or DNA damage induced by smoking. How key areas of COPD pathogenesis, such as inflammation, oxidative stress and protease imbalance may contribute to subsequent development of cancer will also be covered. Finally the possibility that consequences of COPD, such as hypoxia, influence carcinogenesis will be reviewed. By understanding the pathogenesis of COPD and lung cancer in detail it is possible that new treatments may be developed and the risk of lung cancer in COPD may be reduced.

Distinct quantitative computed tomography emphysema patterns are associated with physiology and function in smokers

RATIONALE

Emphysema occurs in distinct pathologic patterns, but little is known about the epidemiologic associations of these patterns. Standard quantitative measures of emphysema from computed tomography (CT) do not distinguish between distinct patterns of parenchymal destruction.

OBJECTIVES

To study the epidemiologic associations of distinct emphysema patterns with measures of lung-related physiology, function, and health care use in smokers.

METHODS

Using a local histogram-based assessment of lung density, we quantified distinct patterns of low attenuation in 9,313 smokers in the COPDGene Study. To determine if such patterns provide novel insights into chronic obstructive pulmonary disease epidemiology, we tested for their association with measures of physiology, function, and health care use.

MEASUREMENTS AND MAIN RESULTS

Compared with percentage of low-attenuation area less than -950 Hounsfield units (%LAA-950), local histogram-based measures of distinct CT low-attenuation patterns are more predictive of measures of lung function, dyspnea, quality of life, and health care use. These patterns are strongly associated with a wide array of measures of respiratory physiology and function, and most of these associations remain highly significant (P < 0.005) after adjusting for %LAA-950. In smokers without evidence of chronic obstructive pulmonary disease, the mild centrilobular disease pattern is associated with lower FEV1 and worse functional status (P < 0.005).

CONCLUSIONS

Measures of distinct CT emphysema patterns provide novel information about the relationship between emphysema and key measures of physiology, physical function, and health care use. Measures of mild emphysema in smokers with preserved lung function can be extracted from CT scans and are significantly associated with functional measures.

High correlation of the response of upper and lower lobe small airway epithelium to smoking

The distribution of lung disease induced by inhaled cigarette smoke is complex, depending on many factors. With the knowledge that the small airway epithelium (SAE) is the earliest site of smoking-induced lung disease, and that the SAE gene expression is likely sensitive to inhaled cigarette smoke, we compared upper vs. lower lobe gene expression in the SAE within the same cigarette smokers to determine if the gene expression patterns were similar or different. Active smokers (n = 11) with early evidence of smoking-induced lung disease (normal spirometry but low diffusing capacity) underwent bronchoscopy and brushing of the upper and lower lobe SAE in order to compare upper vs lower lobe genome-wide and smoking-responsive gene expression by microarray. Cluster and principal component analysis demonstrated that, for each individual, the expression of the known SAE smoking-responsive genes were highly correlated in upper and lower lobe pairs, although, as expected, there were differences in the smoking-induced changes in gene expression from individual to individual. These observations support the concept that the heterogeneity observed among smokers in the anatomic distribution of smoking-induced disease are not secondary to the topographic differences in the effects of cigarette smoke on the airway epithelium.

Chronic obstructive pulmonary disease and bronchiectasis

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease (COPD) and bronchiectasis are two different but related diseases that occur separately, but can coexist. In this review, we will examine the recent research regarding patients with COPD who have coexisting bronchiectasis.

RECENT FINDINGS

Recent research has focused on defining distinct COPD phenotypes with the ultimate goal of changing the outcomes using tailored therapies. A frequent exacerbator phenotype has been identified. COPD patients with Pseudomonas aeruginosa are a phenotype with worse outcomes. Patients with coexisting COPD and bronchiectasis may represent a unique phenotype.

SUMMARY

Patients with coexisting COPD and bronchiectasis could represent a unique phenotype with more severe disease, worse outcomes, more isolation of potentially pathogenic microorganisms, and more frequent exacerbations, with the potential for targeted therapies.

Updates on the COPD gene list

A genetic contribution to develop chronic obstructive pulmonary disease (COPD) is well established. However, the specific genes responsible for enhanced risk or host differences in susceptibility to smoke exposure remain poorly understood. The goal of this review is to provide a comprehensive literature overview on the genetics of COPD, highlight the most promising findings during the last few years, and ultimately provide an updated COPD gene list. Candidate gene studies on COPD and related phenotypes indexed in PubMed before January 5, 2012 are tabulated. An exhaustive list of publications for any given gene was looked for. This well-documented COPD candidate-gene list is expected to serve many purposes for future replication studies and meta-analyses as well as for reanalyzing collected genomic data in the field. In addition, this review summarizes recent genetic loci identified by genome-wide association studies on COPD, lung function, and related complications. Assembling resources, integrative genomic approaches, and large sample sizes of well-phenotyped subjects is part of the path forward to elucidate the genetic basis of this debilitating disease.

Recent findings in chronic obstructive pulmonary disease by using quantitative computed tomography

Chronic obstructive pulmonary disease (COPD) is characterized by an incompletely reversible airflow limitation that results from a combination of airway wall remodeling and emphysematous lung destruction. Forced expiratory volume in 1s (FEV(1)) has been considered the gold standard for diagnosis, classification, and follow-up in patients with COPD, but it has certain limitations and it is still necessary to find other noninvasive modalities to complement FEV(1) to evaluate the effect of therapeutic interventions and the pathogenesis of COPD. Quantitative computed tomography (CT) has partly met this demand. The extent of emphysema and airway dimensions measured using quantitative CT are associated with morphological and functional changes and clinical symptoms in patients with COPD. Phenotyping COPD based on quantitative CT has facilitated interventional and genotypic studies. Recent advances in COPD findings with quantitative CT are discussed in this review.

Genetic variants in antioxidant genes are associated with diisocyanate-induced asthma

Diisocyanates are a common cause of occupational asthma, but risk factors are not well defined. A case-control study was conducted to investigate whether genetic variants of antioxidant defense genes, glutathione S-transferases (GSTM1, GSTT1, GSTM3, GSTP1), manganese superoxide dismutase (SOD2), and microsomal epoxide hydrolase (EPHX1) are associated with increased susceptibility to diisocyanate-induced asthma (DA). The main study population consisted of 353 Caucasian French-Canadians from among a larger sample of 410 diisocyanate-exposed workers in three groups: workers with specific inhalation challenge (SIC) confirmed DA (DA(+), n = 95); symptomatic diisocyanate workers with a negative SIC (DA(-), n = 116); and asymptomatic exposed workers (AW, n = 142). Genotyping was performed on genomic DNA, using a 5'-nuclease PCR assay. The SOD2 rs4880, GSTP1 rs1695, and EPHX1 rs2740171 variants were significantly associated with DA in both univariate and multivariate analyses. In the first logistic regression model comparing DA(+) and DA(-) groups, SOD2 rs4880, GSTM1 (null), GSTP1 rs762803, and EPHX1 rs2854450 variants were associated with DA (p = 0.004, p = 0.047, p = 0.021, p <0.001, respectively). Genotype combinations GSTT1*GSTP1 rs762803, GSTM1*EPHX1 rs2854450, EPHX1 rs2740168*EPHX1 rs1051741, and GSTP1 rs762803*EPHX1 rs2740168 were also associated with DA in this model (p = 0.027, p = 0.002, p = 0.045, p = 0.044, respectively). The GSTP1 rs1695 and EPHX1 rs1051741 and rs2740171 variants showed an association with DA in the second model comparing DA(+) and AW groups (p = 0.040, p = 0.019, p = 0.002, respectively). The GSTM3 rs110913*EPHX1 rs1051741 genotype combination was also associated with DA under this model (p = 0.042). The results suggest that variations in SOD2, GST, and EPHX1 genes and their interactions contribute to DA susceptibility.

Emphysema distribution and annual changes in pulmonary function in male patients with chronic obstructive pulmonary disease

BACKGROUND

The progression of chronic obstructive pulmonary disease (COPD) considerably varies among patients. Those with emphysema identified by quantitative computed tomography (CT) are associated with the rapid progression assessed by forced expiratory volume in one second (FEV1). However, whether the rate of the decline in lung function is independently affected by the regional distribution or the severity of emphysema in the whole lung is unclear.

METHODS

We followed up 131 male patients with COPD for a median of 3.7 years. We measured wall area percent (WA%) in right apical segmental bronchus, total lung volume, percent low attenuation volume (LAV%), and the standard deviation (SD) of LAV% values from CT images of 10 isovolumetric partitions (SD-LAV) as an index of cranial-caudal emphysema heterogeneity. Annual changes in FEV1 were then determined using a random coefficient model and relative contribution of baseline clinical parameters, pulmonary function, and CT indexes including LAV%, SD-LAV, and WA% to annual changes in FEV1 were examined.

RESULTS

The mean (SD) annual change in FEV1 was -44.4 (10.8) mL. Multivariate random coefficient model showed that higher baseline FEV1, higher LAV%, current smoking, and lower SD-LAV independently contributed to an excessive decline in FEV1, whereas ratio of residual volume to total lung capacity, ratio of diffusing capacity to alveolar ventilation, and WA% did not, after adjusting for age, height, weight, and ratio of CT-measured total lung volume to physiologically-measured total lung capacity.

CONCLUSIONS

A more homogeneous distribution of emphysema contributed to an accelerated decline in FEV1 independently of baseline pulmonary function, whole-lung emphysema severity, and smoking status. In addition to whole-lung analysis of emphysema, CT assessment of the cranial-caudal distribution of emphysema might be useful for predicting rapid, progressive disease and for developing a targeted strategy with which to prevent disease progression.

Targeted deletion of Jun/AP-1 in alveolar epithelial cells causes progressive emphysema and worsens cigarette smoke-induced lung inflammation

Chronic obstructive pulmonary disease appears to occur slowly and progressively over many years, with both genetic factors and environmental modifiers contributing to its pathogenesis. Although the c-Jun/activator protein 1 transcriptional factor regulates cell proliferation, apoptosis, and inflammatory responses, its role in lung pathogenesis is largely unknown. In this study, we report decreased expression levels of c-Jun mRNA and protein in the lung tissues of patients with advanced chronic obstructive pulmonary disease, and the genetic deletion of c-Jun specifically in alveolar epithelial cells causes progressive emphysema with lung inflammation and alveolar air space enlargement, which are cardinal features of emphysema. Although mice lacking c-Jun specifically in lung alveolar epithelial cells appear normal at the age of 6 weeks, when exposed to long-term cigarette smoke, c-Jun-mutant mice display more lung inflammation with perivascular and peribronchiolar infiltrates compared with controls. These results demonstrate that the c-Jun/activator protein 1 pathway is critical for maintaining lung alveolar cell homeostasis and that loss of its expression can contribute to lung inflammation and progressive emphysema.

Novel outcomes and end points: biomarkers in chronic obstructive pulmonary disease clinical trials

Biomarker development in chronic obstructive pulmonary disease (COPD) is a nascent field, in part because of the complexity underlying COPD pathogenesis. The objective of this review is to provide examples of how biomarkers may be effectively applied in clinical trials of COPD by limiting their use to specific contexts and using them to answer well delineated questions. Types of novel outcomes or "biomarkers" that may be useful in clinical trials in COPD include analyses performed on bronchoscopically obtained samples, sputum, exhaled gases, blood, and urine and "ex vivo" assays performed using biological samples obtained from trial participants. These novel biological outcomes are rarely useful as primary end points in phase III clinical trials in COPD, because they are not typically recognized by the U.S. Food and Drug Administration or other regulatory agencies. More commonly, the applications of these outcomes include "proof-of-concept" decisions, demonstration that the intervention had the intended pharmacologic or biological effect, identification of patient subgroups that benefit most, and safety monitoring. Examples given in this review include outcomes used in a phase IIA study of an inhaled small molecule inhibitor of epidermal growth factor receptor. Large observational studies of COPD, including the ECLIPSE, COPDGene, and SPIROMICS studies will further inform our use of biomarkers in COPD clinical trials. To encourage the application of novel biomarkers in clinical trials, the Food and Drug Administration has developed a new process for biomarker "qualification." This process has been designed to be more efficient and to promote consensus building and sharing of preclinical data.

The National Emphysema Treatment Trial (NETT): Part I: Lessons learned about emphysema

The National Emphysema Treatment Trial (NETT) was a multicenter prospective randomized controlled trial that compared optimal medical treatment, including pulmonary rehabilitation, with optimal medical treatment plus lung volume reduction surgery (LVRS). It was the largest and most complete collection of patient demographic, clinical, physiological, and radiographic data ever compiled in severe emphysema. NETT investigated the effects of optimal medical management and LVRS on short- and long-term survival, as well as lung function, exercise performance, and quality of life. NETT also provided much information regarding the evaluation and prognosis of severe emphysema; specifically the important negative influences that hyperinflation and small airway disease have on survival. NETT emphasized the importance of addressing nonpulmonary issues such as nutrition, cardiac disease, anxiety, and depression in emphysema. NETT demonstrated that physiological, genomic, and radiographic phenotype can predict patient survival as well as response to treatment. Because the major purpose of NETT was to compare bilateral LVRS with optimal medical treatment in emphysema, patients enrolled into NETT were comprehensively characterized and selected to have a specific window of airflow obstruction and hyperinflation and to lack significant comorbidities. The NETT patient population’s restrictive features offer distinct advantages (well-characterized predominant emphysematous phenotype) and disadvantages (lack of comorbidities and significant chronic bronchitis) that must be considered when interpreting the implications of these results. Herein, we provide a summary of the major NETT findings that provide insight into the evaluation and medical treatment of emphysema.

Equating quantitative emphysema measurements on different CT image reconstructions

PURPOSE

To mathematically model the relationship between CT measurements of emphysema obtained from images reconstructed using different section thicknesses and kernels and to evaluate the accuracy of the models for converting measurements to those of a reference reconstruction.

METHODS

CT raw data from the lung cancer screening examinations of 138 heavy smokers were reconstructed at 15 different combinations of section thickness and kernel. An emphysema index was quantified as the percentage of the lung with attenuation below -950 HU (EI950). Linear, quadratic, and power functions were used to model the relationship between EI950 values obtained with a reference 1 mm, medium smooth kernel reconstruction and values from each of the other 14 reconstructions. Preferred models were selected using the corrected Akaike information criterion (AICc), coefficients of determination (R2), and residuals (conversion errors), and cross-validated by a jackknife approach using the leave-one-out method.

RESULTS

The preferred models were power functions, with model R2 values ranging from 0.949 to 0.998. The errors in converting EI950 measurements from other reconstructions to the 1 mm, medium smooth kernel reconstruction in leave-one-out testing were less than 3.0 index percentage points for all reconstructions, and less than 1.0 index percentage point for five reconstructions. Conversion errors were related in part to image noise, emphysema distribution, and attenuation histogram parameters. Conversion inaccuracy related to increased kernel sharpness tended to be reduced by increased section thickness.

CONCLUSIONS

Image reconstruction-related differences in quantitative emphysema measurements were successfully modeled using power functions.

Pathogenic triad in COPD: oxidative stress, protease-antiprotease imbalance, and inflammation

Patients with chronic obstructive pulmonary disease (COPD) exhibit dominant features of chronic bronchitis, emphysema, and/or asthma, with a common phenotype of airflow obstruction. COPD pulmonary physiology reflects the sum of pathological changes in COPD, which can occur in large central airways, small peripheral airways, and the lung parenchyma. Quantitative or high-resolution computed tomography is used as a surrogate measure for assessment of disease progression. Different biological or molecular markers have been reported that reflect the mechanistic or pathogenic triad of inflammation, proteases, and oxidants and correspond to the different aspects of COPD histopathology. Similar to the pathogenic triad markers, genetic variations or polymorphisms have also been linked to COPD-associated inflammation, protease–antiprotease imbalance, and oxidative stress. Furthermore, in recent years, there have been reports identifying aging-associated mechanistic markers as downstream consequences of the pathogenic triad in the lungs from COPD patients. For this review, the authors have limited their discussion to a review of mechanistic markers and genetic variations and their association with COPD histopathology and disease status.

Gender differences of airway dimensions in anatomically matched sites on CT in smokers

RATIONALE AND OBJECTIVES

There are limited data on, and controversies regarding gender differences in the airway dimensions of smokers. Multi-detector CT (MDCT) images were analyzed to examine whether gender could explain differences in airway dimensions of anatomically matched airways in smokers.

MATERIALS AND METHODS

We used VIDA imaging software to analyze MDCT scans from 2047 smokers (M:F, 1021:1026) from the COPDGene® cohort. The airway dimensions were analyzed from segmental to subsubsegmental bronchi. We compared the differences of luminal area, inner diameter, wall thickness, wall area percentage (WA%) for each airway between men and women, and multiple linear regression including covariates (age, gender, body sizes, and other relevant confounding factors) was used to determine the predictors of each airway dimensions.

RESULTS

Lumen area, internal diameter and wall thickness were smaller for women than men in all measured airway (18.4 vs 22.5 mm(2) for segmental bronchial lumen area, 10.4 vs 12.5 mm(2) for subsegmental bronchi, 6.5 vs 7.7 mm(2) for subsubsegmental bronchi, respectively p < 0.001). However, women had greater WA% in subsegmental and subsubsegmental bronchi. In multivariate regression, gender remained one of the most significant predictors of WA%, lumen area, inner diameter and wall thickness.

CONCLUSION

Women smokers have higher WA%, but lower luminal area, internal diameter and airway thickness in anatomically matched airways as measured by CT scan than do male smokers. This difference may explain, in part, gender differences in the prevalence of COPD and airflow limitation.