Citations

Abstract Rationale Constantly exposed to the external environment and mutagens such as tobacco smoke, human lungs have one of the highest somatic mutation rates among all human organs. However, the relationship of these mutations to lung disease and function is not known. Objectives To identify the prevalence and significance of clonal somatic mutations in chronic lung diseases. Methods We analyzed the clonal somatic mutations from 1,251 samples of normal and diseased noncancerous lung tissue RNA sequencing with paired whole-genome sequencing from the Lung Tissue Research Consortium. We examined the associations of somatic mutations with lung function, disease status, and computationally deconvoluted cell types in two of the most common diseases represented in our dataset, chronic obstructive pulmonary disease (COPD; 29%) and idiopathic pulmonary fibrosis (IPF; 13%). Measurements and Main Results Clonal somatic mutational burden was associated with reduced lung function in both COPD and IPF. We identified an increased prevalence of clonal somatic mutations in individuals with IPF compared with normal control subjects and individuals with COPD independent of age and smoking status. IPF clonal somatic mutations were enriched in disease-related and airway epithelial–expressed genes such as MUC5B in IPF. Patients who were MUC5B risk variant carriers had increased odds of developing somatic mutations of MUC5B that were explained by increased expression of MUC5B. Conclusions Our identification of an increased prevalence of clonal somatic mutation in diseased lung that correlates with airway epithelial gene expression and disease severity highlights for the first time the role of somatic mutational processes in lung disease genetics.

Abstract Rationale Multiple studies have demonstrated an increased risk of chronic obstructive pulmonary disease (COPD) in heterozygous carriers of the AAT (alpha-1 antitrypsin) Z allele. However, it is not known if MZ subjects with COPD are phenotypically different from noncarriers (MM genotype) with COPD. Objectives To assess if MZ subjects with COPD have different clinical features compared with MM subjects with COPD. Methods Genotypes of SERPINA1were ascertained by using whole-genome sequencing data in three independent studies. We compared outcomes between MM subjects with COPD and MZ subjects with COPD in each study and combined the results in a meta-analysis. We performed longitudinal and survival analyses to compare outcomes in MM and MZ subjects with COPD over time. Measurements and Main Results We included 290 MZ subjects with COPD and 6,184 MM subjects with COPD across the three studies. MZ subjects had a lower FEV1% predicted and greater quantitative emphysema on chest computed tomography scans compared with MM subjects. In a meta-analysis, the FEV1was 3.9% lower (95% confidence interval [CI], −6.55% to −1.26%) and emphysema (the percentage of lung attenuation areas <−950 HU) was 4.14% greater (95% CI, 1.44% to 6.84%) in MZ subjects. We found one gene, PGF(placental growth factor), to be differentially expressed in lung tissue from one study between MZ subjects and MM subjects. Conclusions Carriers of the AAT Z allele (those who were MZ heterozygous) with COPD had lower lung function and more emphysema than MM subjects with COPD. Taken with the subtle differences in gene expression between the two groups, our findings suggest that MZ subjects represent an endotype of COPD.

Abstract Objective To investigate the natural history of fibrotic lung disease in recipients of a single lung transplant for scleroderma-associated interstitial lung disease (ILD). Methods Global ILD (including ground glass, nodular opacities and fibrosis) was categorized into severity quintiles on first and last post-transplant CT scans, and percent fibrosis by manual contouring was also determined, in nine single lung transplant recipients. Quantitative mean lung densities and volumes for the native and allograft lungs were also acquired. Results In the native lung, global ILD severity quintile worsened in two cases and percent fibrosis worsened in four cases (range 5–28%). In the lung allograft, one case each developed mild, moderate and severe ILD; of these, new fibrotic ILD (involving <10% of lung) occurred in two cases and acute cellular rejection occurred in one. The average change in native lung density over time was +2.2 Hounsfield Units per year and lung volume +1.4 ml per year, whereas the allograft lung density changed by –5.5 Hounsfield Units per year and total volume +27 ml per year (P = 0.011 and P = 0.039 for native vs allograft density and volume comparisons, respectively). Conclusions While the course of ILD in the native and transplanted lungs varied in this series, these cases illustrate that disease progression is common in the native lung, suggesting that either the immune process continues to target autoantigens or ongoing fibrotic pathways are active in the native lung. Mild lung disease may occur in the allograft after several years due to either allograft rejection or recurrent mild ILD.

Abstract Rationale Frailty represents an increased vulnerability to adverse health outcomes. The frailty phenotype conceptual model (three or more patient attributes of wasting, exhaustion, low activity, slowness, and weakness) is associated with increased morbidity and mortality in geriatric populations. Objectives Our objective was to describe the risks associated with frailty in patients with chronic obstructive pulmonary disease. Methods Data from the National Emphysema Treatment Trial (NETT) were retrospectively analyzed. The frailty phenotype conceptual model was operationalized as three or more frailty parameters (a body mass index decrease of ≥5% over 12 months, self-reported exhaustion, low 6-minute walk distance, or physical activity or respiratory muscle strength in the lowest quartile). Frail participants were compared with participants with two or fewer frailty parameters. Participants were followed starting 12 months after NETT randomization (to minimize surgical effect) for 24 months. Univariate, multivariate, Kaplan-Meier, and Cox proportional hazard analyses were performed, adjusting for treatment arm, age, modified Medical Research Council dyspnea scale, sex, and baseline forced expiratory volume in 1 second (FEV1). Multiple imputation was used for missing values. Results The participants (N = 902) were predominantly white (94.5%) males (59.5%), with a median age of 67 years (interquartile range, 63–70 yr) and a median FEV1% predicted of 26 (interquartile range, 20–33). Six percent of the participants (95% confidence interval [CI], 4.5 to 7.6) were frail. The incidence rate of frailty was 6.4 per 100 person-years. Frail participants reported significantly worse disease-specific and overall quality of life by St. George’s Respiratory Questionnaire total score (mean difference of 11.6; 95% CI, 7.6 to 15.6; P < 0.001), mental composite on Medical Outcomes Survey Short Form-36 (mean difference −6.8; 95% CI, −10.0 to −3.6; P < 0.001), and physical composite scores on Medical Outcomes Survey Short Form-36 (mean difference −16.7; 95% CI, −21.3 to −12.1; P = 0.001). Frail participants had an increased rate of hospitalization (adjusted hazard ratio, 1.6; 95% CI, 1.1 to 2.5; P = 0.02) and an adjusted increase in hospital use of 8.0 days (95% CI, 4.4 to 11.6; P < 0.001) compared with nonfrail participants. Frail participants had a higher mortality rate (adjusted hazard ratio, 1.4; 95% CI, 0.97 to 2.0; P = 0.07). Conclusions Among adults with chronic obstructive pulmonary disease, our measure of frailty (modified from the Fried frailty phenotype) was associated with incident and longer-duration hospitalization, and with poor quality of life.

Abstract Rationale Disability guidelines are often based on pulmonary function testing, but factors other than lung function influence how an individual experiences physiologic impairment. Age may impact the perception of impairment in adults with chronic lung disease. Objectives To determine if self-report of physical functional impairment differs between older adults with chronic lung disease compared with younger adults with similar degrees of lung function impairment. Methods The Lung Tissue Research Consortium provided data on 981 participants with chronic obstructive pulmonary disease and interstitial lung disease who were well characterized with clinical, radiological, and pathological diagnoses. We used multiple logistic regression to determine if responses to health status questions (from the Short Form-12 and St. George’s Respiratory Questionnaire) related to perception of impairment differed in older adults (age ≥ 65 yr, n = 427) compared with younger adults (age < 65 yr, n = 393). Measurements and Main Results Pulmonary function was higher in older adults (median FEV1 %, 70) compared with younger adults (median FEV1 %, 62) (P < 0.001), whereas the median 6-minute-walk distance was similar between groups (372 m vs. 388 m, P = 0.21). After adjusting for potential confounders, older adults were less likely to report that their health limited them significantly in performing moderate activities (odds ratio [OR], 0.36; 95% confidence interval [CI], 0.22–0.58) or climbing several flights of stairs (OR, 0.51; 95% CI, 0.34–0.77). The odds of reporting that their physical health limited the kinds of activities they performed were reduced by 63% in older adults (OR, 0.37; 95% CI, 0.24–0.58), and, similarly, the odds of reporting that their health caused them to accomplish less than they would like were also lower in older adults (OR, 0.39; 95% CI, 0.25–0.60). The OR for reporting that their breathing problem stops them from doing most things or everything was 0.35 (95% CI, 0.22–0.55) in older adults versus younger adults. Conclusions Older adults with chronic lung disease were less likely to report significant impairment in their activities compared with younger adults, suggesting they may perceive less limitation.

Abstract Rationale The course of lung function decline for smokers with early airflow obstruction remains undefined. It is also unclear which early spirometric characteristics identify individuals at risk for rapid decline and increased mortality. Objectives To determine the association between spirometric measures and 5-year decline in FEV1 and 12-year mortality. Methods We analyzed longitudinal data from the Lung Health Study, a clinical trial of intensive smoking cessation intervention with or without bronchodilator therapy in 5,887 smokers with mild to moderate airflow obstruction. Participants were stratified into bins of baseline FEV1 to FVC ratio, using bins of 5%, and separately into bins of Z-score (difference between actual and predicted FEV1/FVC, normalized to SD of predicted FEV1/FVC). Associations between spirometric measures and FEV1 decline and mortality were determined after adjusting for baseline characteristics and time-varying smoking status. Measurements and Main Results The cohort was approximately two-thirds male, predominantly of white race (96%), and with mean age of 49 ± 7 years. In general, individuals with lower lung function by any metric had more rapid adjusted FEV1 decline. A threshold for differential decline was present at FEV1/FVC less than 0.65 (P < 0.001) and Z-score less than −2 (2.3 percentile) (P < 0.001). At year 12, 575 (7.2%) of the cohort had died. Lower thresholds of each spirometric metric were associated with increasing adjusted hazard of death. Conclusions Smokers at risk or with mild to moderate chronic obstructive pulmonary disease have accelerated lung function decline. Individuals with lower baseline FEV1/FVC have more rapid decline and worse mortality.

Abstract Rationale In studies that address health-related quality of life (QoL) and survival, subjects who die are usually censored from QoL assessments. This practice tends to inflate the apparent benefits of interventions with a high risk of mortality. Assessing a composite QoL-death outcome is a potential solution to this problem. Objectives To determine the effect of lung volume reduction surgery (LVRS) on a composite endpoint consisting of the occurrence of death or a clinically meaningful decline in QoL defined as an increase of at least eight points in the St. George's Respiratory Questionnaire total score from the National Emphysema Treatment Trial. Methods In patients with chronic obstructive pulmonary disease and emphysema randomized to receive medical treatment (n = 610) or LVRS (n = 608), we analyzed the survival to the composite endpoint, the hazard functions and constructed prediction models of the slope of QoL decline. Measurements and Main Results The time to the composite endpoint was longer in the LVRS group (2 years) than the medical treatment group (1 year) (P < 0.0001). It was even longer in the subsets of patients undergoing LVRS without a high risk for perioperative death and with upper-lobe-predominant emphysema. The hazard for the composite event significantly favored the LVRS group, although it was most significant in patients with predominantly upper-lobe emphysema. The beneficial impact of LVRS on QoL decline was most significant during the 2 years after LVRS. Conclusions LVRS has a significant effect on the composite QoL-survival endpoint tested, indicating its meaningful palliative role, particularly in patients with upper-lobe–predominant emphysema.