Childhood Lung Function Predicts Adult Chronic Obstructive Pulmonary Disease and Asthma-Chronic Obstructive Pulmonary Disease Overlap Syndrome

Chronic obstructive pulmonary disease - diagnosis and management of stable disease; a personalized approach to care, using the treatable traits concept based on clinical phenotypes. Position paper of the Czech Pneumological and Phthisiological Society

This position paper has been drafted by experts from the Czech national board of diseases with bronchial obstruction, of the Czech Pneumological and Phthisiological Society. The statements and recommendations are based on both the results of randomized controlled trials and data from cross-sectional and prospective real-life studies to ensure they are as close as possible to the context of daily clinical practice and the current health care system of the Czech Republic. Chronic Obstructive Pulmonary Disease (COPD) is a preventable and treatable heterogeneous syndrome with a number of pulmonary and extrapulmonary clinical features and concomitant chronic diseases. The disease is associated with significant mortality, morbidity and reduced quality of life. The main characteristics include persistent respiratory symptoms and only partially reversible airflow obstruction developing due to an abnormal inflammatory response of the lungs to noxious particles and gases. Oxidative stress, protease-antiprotease imbalance and increased numbers of pro-inflammatory cells (mainly neutrophils) are the main drivers of primarily non-infectious inflammation in COPD. Besides smoking, household air pollution, occupational exposure, low birth weight, frequent respiratory infections during childhood and also genetic factors are important risk factors of COPD development. Progressive airflow limitation and airway remodelling leads to air trapping, static and dynamic hyperinflation, gas exchange abnormalities and decreased exercise capacity. Various features of the disease are expressed unequally in individual patients, resulting in various types of disease presentation, emerging as the "clinical phenotypes" (for specific clinical characteristics) and "treatable traits" (for treatable characteristics) concept. The estimated prevalence of COPD in Czechia is around 6.7% with 3,200-3,500 deaths reported annually. The elementary requirements for diagnosis of COPD are spirometric confirmation of post-bronchodilator airflow obstruction (post-BD FEV₁/VCmax <70%) and respiratory symptoms assessement (dyspnoea, exercise limitation, cough and/or sputum production. In order to establish definite COPD diagnosis, a five-step evaluation should be performed, including: 1/ inhalation risk assessment, 2/ symptoms evaluation, 3/ lung function tests, 4/ laboratory tests and 5/ imaging. At the same time, all alternative diagnoses should be excluded. For disease classification, this position paper uses both GOLD stages (1 to 4), GOLD groups (A to D) and evaluation of clinical phenotype(s). Prognosis assessment should be done in each patient. For this purpose, we recommend the use of the BODE or the CADOT index. Six elementary clinical phenotypes are recognized, including chronic bronchitis, frequent exacerbator, emphysematous, asthma/COPD overlap (ACO), bronchiectases with COPD overlap (BCO) and pulmonary cachexia. In our concept, all of these clinical phenotypes are also considered independent treatable traits. For each treatable trait, specific pharmacological and non-pharmacological therapies are defined in this document. The coincidence of two or more clinical phenotypes (i.e., treatable traits) may occur in a single individual, giving the opportunity of fully individualized, phenotype-specific treatment. Treatment of COPD should reflect the complexity and heterogeneity of the disease and be tailored to individual patients. Major goals of COPD treatment are symptom reduction and decreased exacerbation risk. Treatment strategy is divided into five strata: risk elimination, basic treatment, phenotype-specific treatment, treatment of respiratory failure and palliative care, and treatment of comorbidities. Risk elimination includes interventions against tobacco smoking and environmental/occupational exposures. Basic treatment is based on bronchodilator therapy, pulmonary rehabilitation, vaccination, care for appropriate nutrition, inhalation training, education and psychosocial support. Adequate phenotype-specific treatment varies phenotype by phenotype, including more than ten different pharmacological and non-pharmacological strategies. If more than one clinical phenotype is present, treatment strategy should follow the expression of each phenotypic label separately. In such patients, multicomponental therapeutic regimens are needed, resulting in fully individualized care. In the future, stronger measures against smoking, improvements in occupational and environmental health, early diagnosis strategies, as well as biomarker identification for patients responsive to specific treatments are warranted. New classes of treatment (inhaled PDE3/4 inhibitors, single molecule dual bronchodilators, anti-inflammatory drugs, gene editing molecules or new bronchoscopic procedures) are expected to enter the clinical practice in a very few years.

Asthma-chronic obstructive pulmonary disease overlap syndrome

Overlap of asthma and chronic obstructive lung disease (ACO) in patients with obstructive lung disease is growing in recognition, though there is no consistent agreement on the diagnostic criteria for the disease process. Patients with ACO have distinct clinical characteristics and trajectories, which are representative of a heterogenous, multifactorial, and incompletely understood inflammatory pathophysiology. Current treatment strategies are focused on titration of inhaled therapies such as long-acting bronchodilators, with increasing interest in the use of targeted biologic therapies aimed at the underlying inflammatory mechanisms. Future directions for research will focus on elucidating the varied inflammatory signatures leading to ACO, the development of consistent diagnostic criteria and biomarkers of disease, and improving the clinical management with an eye toward targeted therapies.

Low lung function in the developing world is analogous to stunting: a review of the evidence

Background: Low vital capacity, one of the consequences of restricted lung growth, is a strong predictor of cardiovascular mortality. Vital capacity is lower in the developing world than the developed world, even after adjusting for height, weight and gender. This difference is typically dismissed as ethnic variation, adjusted for by redefining normal. Whether this is a consequence of stunted lung growth, rather than just genetically smaller lungs, has not been investigated in detail. Therefore, we sought to compare factors implicated in both stunting and lung development, particularly in the developing world.

Methods: We conducted a manual screen of articles identified through Google Scholar and assessed risk of bias. No language restrictions were applied, so long as there was an associated English abstract. We queried VizHub (Global Burden of Disease Visualization Tool) and Google Dataset search engines for disease burden and genome wide association studies.  The scope of the article and the heterogeneity of the outcome measures reported required a narrative review of available evidence. To the extent possible, the review follows PRISMA reporting guidelines.

Results: Early life influences operate in synergism with genetic, environmental and nutritional factors to influence lung growth and development in children.  Low lung function and stunting have common anthropometric, environmental and nutritional correlates originating during early development. Similar anthropometric correlates shared chronic inflammatory pathways, indicated that the two conditions were analogous.

Conclusion: The analogy between poor lung function and stunting is conspicuous in the developing world, with malnutrition at the center of non -achievement of growth potential, susceptibility to infectious diseases and intrauterine programming for metabolic syndrome. This counter the idea of redefining the normal for lung function measurements, since observed inter-ethnic variations are likely a mix of natural genetic differences as well as differences in nurture such that reduced lung function reflects early life adversities.

Pulmonary function in Williams-Beuren syndrome: Spirometric data of 22 Italian patients

Williams-Beuren syndrome (WBS) is caused by an haploinsufficiency of the 7q11.2 region which involves the elastin gene (ELN). A deficiency of elastin is a known pathophysiological mechanism of emphysema/chronic obstructive pulmonary disease (COPD). A previous study hypothesized a higher risk of COPD in WBS patients. Herein, this phenomenon was further investigated looking for a possible correlation between COPD and WBS. Dynamic lung volumes (forced vital capacity [FVC], FEV1, FEV1/FVC) were measured in 22 patients (age range 18.9 ± 7.4 years) affected with WBS, genetically confirmed, correlating these parameters to respiratory risk factors. Dyspnea, cough and wheezing were detected in 6/22 (27%) patients. Obstructive and restrictive patterns were identified in 6/22 (27%) and 2/22 (9%) cases, respectively with no evidence of irreversible obstruction. CVF, FEV1 and FEV1/CVF mean values were all normal, with values of 91.3% (n.v. > 80%), 84.2% (n.v. > 80%) and 0.82 (n.v. > 0.7), respectively. The severity of the comorbidities did not show a cause-effect relation with the respiratory patterns, nevertheless patients treated with anti-hypertensive drugs had poorer pulmonary function. Our findings are in accordance with previous observations, showing that emphysema/COPD is not a typical finding in young patients with WBS. However, a respiratory function assessment should be included in the follow-up of WBS patients, especially in adolescents/young adults under treatment with anti-hypertensive drugs.

Postnatal dexamethasone exposure and lung function in adolescents born very prematurely

We previously demonstrated corticosteroid administration on the neonatal intensive care unit was associated with reduced lung function at 11 to 14 years of age in children born very prematurely. The objective of this observational study was to assess if lung function remained impaired at 16 to 19 years of age in those who had received postnatal corticosteroids and whether the trajectory of lung function with increasing age differed between those who had and had not received corticosteroids. One hundred and fifty-nine children born prior to 29 weeks of gestational age had comprehensive lung function measurements; 49 had received postnatal dexamethasone. Lung function outcomes were compared between those who had and had not received postnatal dexamethasone after adjustment for neonatal factors. Forced expiratory flow at 75%, 50%, 25% and 25-75% of the expired vital capacity, forced expiratory volume in one second, peak expiratory flow and forced vital capacity and lung volumes (total lung capacity and residual volume) were assessed. The majority of results were significantly lower in those who received dexamethasone (between 0.61 to 0.78 standard deviations). Lung function reduced as the number of courses of dexamethasone increased. Between 11 and 14 years and 16 to 19 years, lung function improved in the unexposed group, but forced expiratory flow at 75% of the expired vital capacity and forced expiratory volume in one second deteriorated in those who had received postnatal corticosteroids (p = 0.0006). These results suggest that prematurely born young people who received postnatal corticosteroids may be at risk of premature onset of chronic obstructive pulmonary disease.

Impact of the Local Inflammatory Environment on Mucosal Vitamin D Metabolism and Signaling in Chronic Inflammatory Lung Diseases

Vitamin D plays an active role in the modulation of innate and adaptive immune responses as well as in the protection against respiratory pathogens. Evidence for this immunomodulatory and protective role is derived from observational studies showing an association between vitamin D deficiency, chronic airway diseases and respiratory infections, and is supported by a range of experimental studies using cell culture and animal models. Furthermore, recent intervention studies have now shown that vitamin D supplementation reduces exacerbation rates in vitamin D-deficient patients with chronic obstructive pulmonary disease (COPD) or asthma and decreases the incidence of acute respiratory tract infections. The active vitamin D metabolite, 1,25-dihydroxy-vitamin D (1,25(OH)₂D), is known to contribute to the integrity of the mucosal barrier, promote killing of pathogens (via the induction of antimicrobial peptides), and to modulate inflammation and immune responses. These mechanisms may partly explain its protective role against infections and exacerbations in COPD and asthma patients. The respiratory mucosa is an important site of local 1,25(OH)₂D synthesis, degradation and signaling, a process that can be affected by exposure to inflammatory mediators. As a consequence, mucosal inflammation and other disease-associated factors, as observed in e.g., COPD and asthma, may modulate the protective actions of 1,25(OH)₂D. Here, we discuss the potential consequences of various disease-associated processes such as inflammation and exposure to pathogens and inhaled toxicants on vitamin D metabolism and local responses to 1,25(OH)₂D in both immune- and epithelial cells. We furthermore discuss potential consequences of disturbed local levels of 25(OH)D and 1,25(OH)₂D for chronic lung diseases. Additional insight into the relationship between disease-associated mechanisms and local effects of 1,25(OH)₂D is expected to contribute to the design of future strategies aimed at improving local levels of 1,25(OH)₂D and signaling in chronic inflammatory lung diseases.

Phenotype of ventilatory control in children with moderate to severe persistent asthma and obstructive sleep apnea

STUDY OBJECTIVES

To examine the role of ventilatory control in asthmatic children with obstructive sleep apnea (OSA) and the relationships between measures of ventilatory control, OSA severity, and pulmonary function.

METHODS

Five- to 18-year-old children with persistent asthma and nightly snoring were enrolled in the study. Children had physical examination, pulmonary function test, and polysomnography. Loop and controller gains were derived from 5 min segments which included a sigh during nonrapid eye movement sleep by applying a mathematical model that quantifies ventilatory control from the ensuing responses to the sighs. Plant gain was derived from 5 min segments of spontaneous breathing (i.e. without sighs). Nonparametric statistical tests were used for group comparisons. Cluster analysis was performed using Bayesian profile regression.

RESULTS

One hundred thirty-four children were included in the study, 77 with and 57 without OSA. Plant gain was higher in children with OSA than in those without OSA (p = 0.002). A negative correlation was observed between plant gain and forced expiratory volume in 1 second (p = 0.048) and the ratio of f forced expiratory volume to forced vital capacity (p = 0.02). Plant gain correlated positively with severity of OSA. Cluster analysis demonstrated that children with more severe OSA and abnormal lung function had higher plant gain and a lower controller gain compared with the rest of the population.

CONCLUSIONS

Children with OSA and persistent asthma with abnormal lung function have phenotypic characteristics which consist of diminished capacity of the lungs to maintain blood gas homeostasis reflected by an increase in plant gain and decreased chemoreceptor sensitivity.

Characterisation of pulmonary function trajectories: results from a Brazilian cohort

BACKGROUND

Pulmonary function (PF) trajectories are determined by different exposures throughout the life course. The aim of this study was to investigate characteristics related to PF trajectories from 15 to 22 years in a Brazilian cohort.

METHODS

A birth cohort study (1993 Pelotas Birth Cohort) was conducted with spirometry at 15, 18 and 22 years. PF trajectories were built based on z-score of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and their ratio using a group-based trajectory model. Associations with exposures reported from perinatal to 22 years were described.

RESULTS

Three trajectories, low (LT), average (AT) and high (HT) were identified in 2917 individuals. Wealthiest individuals belonged to the HT of FEV1 (p=0.023). Lower maternal pregestational body mass index (BMI) (22.4±0.2; p<0.001 and 22.1±0.14; p<0.001) and lower birth weight (3164.8±25.4; p=0.029 and 3132.3±19.4; p=0.005) were related to the LT of FEV1 and FVC. Mother's smoking exposure during pregnancy (37.7%; p=0.002), active smoking at ages 18 and 22 years (20.1% and 25.8%; p<0.001) and family history of asthma (44.8%; p<0.001) were related to the LT of FEV1/FVC. Wheezing, asthma and hospitalisations due to respiratory diseases in childhood were related to the LT of both FEV1 and FEV1/FVC. Higher BMIs were related to the HT of FEV1 and FVC at all ages.

CONCLUSIONS

PF trajectories were mainly related to income, pregestational BMI, birth weight, hospitalisation due to respiratory diseases in childhood, participant's BMI, report of wheezing, medical diagnosis and family history of asthma, gestational exposure to tobacco and current smoking status in adolescence and young adult age.

General and Organ Fat Assessed by Magnetic Resonance Imaging and Respiratory Outcomes in Childhood

Rationale: Obesity has been implicated as a pathogenic factor in asthma, but the underlying role of general and organ fat is unclear.Objectives: We hypothesized that organ fat, rather than the total fat mass, increases the risk of asthma.Methods: In a population-based prospective cohort study among 5,421 children aged 10 years, we measured general fat including body mass index and fat mass index by dual-energy X-ray absorptiometry, and organ fat including subcutaneous fat index, visceral fat index, pericardial fat index, and liver fat fraction by magnetic resonance imaging. Lung function was measured by spirometry. Current asthma was assessed by questionnaire.Measurements and Main Results: Higher body mass index and fat mass index were associated with higher FEV₁ (z-score difference [95% confidence interval (CI)], 0.16 [0.14 to 0.19] and z-score difference [95% CI], 0.06 [0.03 to 0.09] per SD score increase, respectively), higher FVC (z-score difference [95% CI], 0.19 [0.17 to 0.22] and z-score difference [95% CI], 0.07 [0.04 to 0.10]), and lower FEV₁/FVC ratio (z-score difference [95% CI], -0.07 [-0.10 to -0.05] and z-score difference [95% CI], -0.03 [-0.06 to -0.00]) but not with forced expiratory flow after exhaling 75% of FVC or asthma. Higher visceral fat index, independent of fat mass index, was associated with higher FVC (z-score difference [95% CI], 0.07 [0.03 to 0.10]), lower FEV₁/FVC (z-score difference [95% CI], -0.05 [-0.09 to -0.01]), and higher risk of asthma (odds ratio, 1.20; 95% CI, 1.01 to 1.43 per SD score increase). No other organ fat measures were independently associated with lung function or asthma.Conclusions: The obesity-asthma link is driven mainly by visceral fat, independent of total fat mass; therefore, abdominal fat might contribute to asthma development.

Airway narrowing and response to simulated deep inspiration in bronchial segments from subjects with fixed airflow obstruction

The volume fraction of extracellular matrix (ECM) within the layer of airway smooth muscle (ASM) is increased in subjects with fixed airflow obstruction. We postulated that changes in ECM within the ASM layer will impact force transmission during induced contraction and/or in response to externally applied stresses like a deep inspiration (DI). Subjects were patients undergoing lung resection surgery who were categorized as unobstructed (n = 12) or "fixed" obstructed (n = 6) on the basis of preoperative spirometry. The response to a DI, assessed by the ratio of isovolumic flows from maximal and partial inspirations (M/P), was also measured preoperatively. M/P was reduced in the obstructed group (P = 0.02). Postoperatively, bronchial segments were obtained from resected tissue, and luminal narrowing to acetylcholine and bronchodilation to simulated DI were assessed in vitro. Airway wall dimensions and the volume fraction of ECM within the ASM were quantified. Maximal airway narrowing to acetylcholine (P = 0.01) and the volume fraction of ECM within the ASM layer (P = 0.02) were increased in the obstructed group, without a change in ASM thickness. Whereas bronchodilation to simulated DI in vitro was not different between obstructed and unobstructed groups, it was correlated with increased M/P (bronchodilation/less bronchoconstriction) in vivo (P = 0.03). The volume fraction of ECM was inversely related to forced expiratory volume in 1 s FEV₁ %predicted (P = 0.04) and M/P (P = 0.01). Results show that in subjects with fixed airflow obstruction the mechanical behavior of the airway wall is altered and there is a contemporaneous shift in the structural composition of the ASM layer.NEW & NOTEWORTHY Cartilaginous airways from subjects with fixed airflow obstruction have an increase in the volume fraction of extracellular matrix within the airway smooth muscle layer. These airways are also intrinsically more reactive to a contractile stimulus, which is expected to contribute to airway hyperresponsiveness in this population, often attributed to geometric mechanisms. In view of these results, we speculate on how changes in extracellular matrix may impact airway mechanics.

Determinants of Lung Function at Age 8.5 Years in a Birth Cohort of Thai Children

BACKGROUND AND AIMS

Early life factors have reported the associations with impaired lung function in later life. In the present study, the birth cohort was followed up longitudinally to investigate the determinants of lung function in Thai children.

METHODS

Cohort subjects were recruited from children born in Songkhla Province in southern Thailand. Data collections were obtained starting from antenatal, at birth, and at 1, 5 and 8.5 years of age. Spirometry was assessed at age 8.5 years. The variables investigated included birth weight, smoke exposure, respiratory diseases during the newborn period and during the first year of life, and asthma diagnosed at age 5 or 8.5 years.

RESULTS

Of 1056 subjects, 892 (84.5%) subjects completed the spirometric measurements. The presence of asthma was the only factor that was significantly associated with a lower forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio, forced expiratory flow at 25-75% vital capacity (FEF25-75%VC) and peak expiratory flow rate (PEFR). The regression analysis found that asthma was significantly associated with a lower FEV1/FVC ratio, FEF25-75%VC, and PEFR value with estimated coefficients ± standard error of -1.27 ± 0.55%, p = 0.02; -131.8 ± 48.2 ml/s, p = 0.006; and -166.2 ± 65.0 ml/s, p = 0.01, respectively. Asthma diagnosed at age 5 or 8.5 years was more likely among children who had lower respiratory tract illness during the first year of life. The odds ratio for the association was 4.81 (95% confidence interval 2.14-10.83, p < 0.001).

CONCLUSION

The main factor associated with lower lung function in Thai cohort subjects was the present of asthma by age 5 or 8.5 years and early respiratory illness was the risk factor for asthma in childhood period.

Risk factors for fixed airflow obstruction in children and adolescents with asthma: 4-Year follow-up

BACKGROUND

Asthma is a disease with reversible bronchoconstriction; however, some patients develop fixed airflow obstruction (FAO). Previous studies have reported the incidence and risk factors of FAO in adults; however, the corresponding factors in children remain poorly understood.

AIM

To evaluate the incidence and risk factors of FAO in children and adolescents with asthma.

METHOD

Observational and prospective cohort study with a 4-year follow-up of clinically stable patients with asthma (from 6-8 years old). Anthropometric data, history of asthma, number of hospitalizations, frequent exacerbations, asthma severity, asthma control, inhaled corticosteroid dose, atopy, and lung function were analyzed as potential risk factors for FAO. FAO was defined by a ratio of the forced expiratory volume in the first second to the forced vital capacity below the lower limit of normal, even after inhaled and oral corticosteroid treatment.

RESULTS

Four hundred and twenty-eight patients were recruited, and 358 were analyzed. The FAO incidence in children and adolescents with asthma was 9.5% (n = 34), starting at 10 years of age. Age, body mass index, hospitalizations for asthma, bronchodilator response, frequent exacerbations, length of exacerbations, and asthma severity were associated with FAO. Frequent exacerbations (odds ratio [OR] = 4.0; 95% confidence interval [CI] = 1.3-11.7) and asthma severity categorized as steps 4 to 5 (OR = 3.5; 95% CI = 1.6-7.6) remained risk factors.

CONCLUSIONS

Frequent exacerbations and asthma severity are the risk factors for FAO in children and adolescents with asthma.

Early Age at Natural Menopause Is Related to Lower Post-Bronchodilator Lung Function. A Longitudinal Population-based Study

Rationale: Poor lung function, a significant predictor of mortality, has been observed in postmenopausal women compared with those still menstruating. Menopausal age is a risk factor for several adverse health outcomes, but little evidence exists on the impact of menopausal age on lung function impairments, especially regarding post-bronchodilator lung function measures.Objectives: To investigate the association between age at menopause and pre- and post-bronchodilator lung function outcomes.Methods: During the sixth-decade follow-up of the Tasmanian Longitudinal Health Study cohort (mean age, 53 yr), information was collected on most recent menstrual period and menopausal status. Lung function was measured at age 7 years and again at 53 years. Multiple linear regression was performed to determine the association between age at menopause and pre- and post-bronchodilator spirometry, controlling for early and adult life confounders.Results: Women reporting an early age at natural menopause (<45 yr) had lower post-bronchodilator forced expiratory volume in 1 second (-168 ml; 95% confidence interval, -273 to -63) and lower forced vital capacity (-186 ml; 95% confidence interval, -302 to -70) than postmenopausal women who experienced menopause at a later age (≥45 yr). No association was observed with forced expiratory volume in 1 second/forced vital capacity ratio. Adjustment for early-life confounders strengthened these associations.Conclusions: This study provides new evidence that early menopause is associated with reduced lung function that is suggestive of restriction, but not obstruction, even after adjustment for early-life confounders. Given the important link between poor lung function and mortality, clinicians should be aware of the risk of diminished lung function in postmenopausal women who experience menopause at an early age.

Variability in Diagnosed Asthma in Young Children in a Large Pediatric Primary Care Network

OBJECTIVE

Our objectives were to 1) quantify the frequency of wheezing episodes and asthma diagnosis in young children in a large pediatric primary care network and 2) assess the variability in practice-level asthma diagnosis, accounting for common asthma risk factors and comorbidities. We hypothesized that significant variability in practice-level asthma diagnosis rates would remain after adjusting for associated predictors.

METHODS

We generated a retrospective longitudinal birth cohort of children who visited 1 of 31 pediatric primary care practices within the first 6 months of life from 1/2005 to 12/2016. Children were observed for up to 8 years or until the end of the observation window. We used multivariable discrete time survival models to evaluate predictors of asthma diagnosis by 3-month age intervals. We compared unadjusted and adjusted proportions of children diagnosed with asthma by practice.

RESULTS

Of the 161,502 children in the cohort, 34,578 children (21%) received at least 1 asthma diagnosis. In multivariable modeling, male gender, minority race/ethnicity, gestational age <34 weeks, allergic rhinitis, food allergy, and prior wheezing episodes were associated with asthma diagnosis. After adjusting for variation in these predictors across practices, the cumulative incidence of asthma diagnosis by practice by age 6 years ranged from 11% to 47% (interquartile range: 24%-29%).

CONCLUSIONS

Across pediatric primary care practices, adjusted incidence of asthma diagnosis by age 6 years ranged widely, though variation gauged by the interquartile range was more modest. Potential sources of practice-level variation, such as differing diagnosis thresholds and labeling of different wheezing phenotypes as "asthma," should be further investigated.

Greenness Availability and Respiratory Health in a Population of Urbanised Children in North-Western Italy

Paediatric Asthma contributes in paediatric global burden of diseases, as the most common chronic disease in children. Children are exposed to many environmental risk-factors, able to determine or worsen respiratory diseases, and contributing to asthma and asthma-like symptoms increases, especially in metropolitan areas. In urban settings, surrounding vegetation (greenness) may provide important benefits to health, including the promotion of physical activity and the mitigation of air and noise pollution. The aim of this study was to investigate the association between greenness and respiratory health. A total of 187 children (10–13 yrs old) were recruited in Turin, the north-western part of Italy. The prevalence of asthma and asthma-like symptoms was calculated from self-reported data collected by SIDRIA questionnaire. Spirometry test was performed to obtain respiratory flow measurements. Greenness was measured at individual level through the Normalised Difference Vegetation Index (NDVI) estimations from remote-sensing images. Higher exposure (3rd tertile vs. 1st tertile) to NDVI was associated to significantly lower ORs for asthma [0.13 CI 95% 0.02–0.7, p = 0.019], bronchitis [0.14 CI 95% 0.05–0.45, p = 0.001], and current wheezing [0.25 CI 95% 0.09–0.70, p = 0.008]. A significative positive association was found between greenness and FEF_25–75, since children exposed to the 2nd tertile of NDVI reported a significantly decreased FEF_25–75 compared to those in the 3rd tertile [B: −2.40; C.I.95%: −0.48–0.01; p = 0.049]. This cross-sectional study provided additional data on still inconsistent literature referring to respiratory health in children and green spaces, attesting a positive effect of greenness in a specific area of Italy. Further research is still needed.

Airway function throughout the lifespan: Pediatric origins of adult respiratory disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of disability and death of adults in the USA and worldwide. While environmental factors such as smoking and air pollution are major contributors to COPD, pediatric respiratory disease and more specifically early childhood wheezing are frequent predisposing factors. It is therefore possible that aggressive prevention and treatment of childhood respiratory illness may modify adult COPD risk. This article reviews some of the physiological factors that may explain the pediatric origins of childhood lung disease. One such factor is the "tracking" of normal lung function which occurs with growth. The maximal expiratory flow volume (MEFV) curve is an ideally suited tool to monitor tracking of airway function over the lifespan, as its relative effort independence makes it highly reliable. Study of the MEFV curve has demonstrated that individuals with similar lung volumes can have large differences in maximal flows, reflecting a disconnection between airway and lung growth ("dysanapsis"). Less than average airway size due to dysanaptic airway growth or airway remodeling may be independent risk factors for the development of COPD and the asthma/COPD overlap syndrome in adult life. There are intriguing early data suggesting that perhaps at least some of this risk is modifiable by improving asthma control with inhaled corticosteroids and minimizing asthma exacerbations.

Telomere length and lung function in a population-based cohort of children and mid-life adults

OBJECTIVE

Telomere length is associated with poorer lung health in older adults, possibly from cumulative risk factor exposure, but data are lacking in pediatric and population-based cohorts. We examined associations of telomere length with lung function in children and mid-life adults.

METHODS

Data were drawn from a population-based cross-sectional study of 11 to 12 year-olds and mid-life adults. Lung function was assessed by spirometric FEV₁ , FVC, FEV ₁ /FVC ratio, and MMEF _25-75 . Telomere length was measured by quantitative polymerase chain reaction from blood and expressed as the amount of telomeric genomic DNA to the beta-globin gene (T/S ratio). Associations of telomere length with spirometric parameters were tested by linear and logistic regression models, adjusting for potential confounders of sex, age, body mass index, socioeconomic position, physical activity, inflammation, asthma, pubertal status, and smoking.

RESULTS

Mean T/S ratio was 1.09 (n = 1206; SD 0.55) in children and 0.81 (n = 1343; SD 0.38) in adults. In adults, for every additional unit in T/S ratio, FEV ₁ /FVC and MMEF _25-75 z-scores were higher (β 0.21 [95% confidence interval, CI; 0.06-0.36] and 0.23 [95% CI; 0.08-0.38], respectively), and the likelihood of being in the lowest quartile for FEV ₁ /FVC and MMEF _25-75 z-scores was lower (odds ratios 0.59 [95% CI, 0.39-0.89] and 0.64 [95% CI, 0.41-0.99], respectively). No evidence of association was seen for adult FEV ₁ or FVC, or any childhood spirometric index after adjustments.

CONCLUSION

Shorter telomere length showed moderate associations with poorer airflow parameters, but not vital capacity (lung volume) in mid-life adults. However, there was no convincing evidence of associations in children.

Childhood pneumonia, pleurisy and lung function: a cohort study from the first to sixth decade of life

INTRODUCTION

Adult spirometry following community-acquired childhood pneumonia has variably been reported as showing obstructive or non-obstructive deficits. We analysed associations between doctor-diagnosed childhood pneumonia/pleurisy and more comprehensive lung function in a middle-aged general population cohort born in 1961.

METHODS

Data were from the prospective population-based Tasmanian Longitudinal Health Study cohort. Analysed lung function was from ages 7 years (prebronchodilator spirometry only, n=7097), 45 years (postbronchodilator spirometry, carbon monoxide transfer factor and static lung volumes, n=1220) and 53 years (postbronchodilator spirometry and transfer factor, n=2485). Parent-recalled histories of doctor-diagnosed childhood pneumonia and/or pleurisy were recorded at age 7. Multivariable linear and logistic regression were used.

RESULTS

At age 7, compared with no episodes, childhood pneumonia/pleurisy-ever was associated with reduced FEV₁:FVC for only those with current asthma (beta-coefficient or change in z-score=-0.20 SD, 95% CI -0.38 to -0.02, p=0.028, p interaction=0.036). At age 45, for all participants, childhood pneumonia/pleurisy-ever was associated with a restrictive pattern: OR 3.02 (1.5 to 6.0), p=0.002 for spirometric restriction (FVC less than the lower limit of normal plus FEV₁:FVC greater than the lower limit of normal); total lung capacity z-score -0.26 SD (95% CI -0.38 to -0.13), p<0.001; functional residual capacity -0.16 SD (-0.34 to -0.08), p=0.001; and residual volume -0.18 SD (-0.31 to -0.05), p=0.008. Reduced lung volumes were accompanied by increased carbon monoxide transfer coefficient at both time points (z-score +0.29 SD (0.11 to 0.49), p=0.001 and +0.17 SD (0.04 to 0.29), p=0.008, respectively).

DISCUSSION

For this community-based population, doctor-diagnosed childhood pneumonia and/or pleurisy were associated with obstructed lung function at age 7 for children who had current asthma symptoms, but with evidence of 'smaller lungs' when in middle age.

Global prevalence of asthma-COPD overlap (ACO) in the general population: a systematic review and meta-analysis

Background

Asthma-COPD overlap (ACO) is a term that encompasses patients with features of both asthma and COPD. To date, the global prevalence of ACO in the general population remains unknown. The objective of this study was to estimate the prevalence of ACO in the general population using a systematic review and meta-analysis.

Methods

A systematic search of ISI Web of Knowledge, MEDLINE/PubMed, and Scopus was performed up to May 2019 to identify studies reporting the prevalence of ACO. Reference lists from identified studies and relevant review articles were also searched. Eligibility criteria were studies reporting the prevalence of ACO, performed in general population, and published in English language. Pooled prevalence of ACO with 95% confidence interval (CI) was calculated using random effects Meta-analysis.

Results

A total of 27 studies were included in this meta-analysis. The Cochran Q test and I² statistics revealed substantial heterogeneity among studies. Based on the random-effects model, the pooled prevalence of ACO was 2.0% (95% CI: 1.4–2.6%) in the general population, 26.5% (95% CI: 19.5–33.6%) among patients with asthma, and 29.6% (95% CI: 19.3–39.9%) among patients with COPD. In addition, for included studies, the global prevalence of asthma-only was 6.2% (95% CI: 5.0–7.4%) and COPD-only was 4.9% (95% CI: 4.3–5.5%).

Conclusion

We estimated the global prevalence of ACO based on population-based studies and found that 2.0% of the general population is affected. However, the prevalence of ACO depends on its diagnostic criteria. Therefore, there is a vital need to better define the ACO diagnostic criteria, management and treatment. It is worth noting that the limitations of the present study include lack of studies in some region of the world and small number of studies included in the subgroup analyses.

Targeting inducible epigenetic reprogramming pathways in chronic airway remodeling

Allergic asthma is a chronic inflammatory airway disease whose clinical course is punctuated by acute exacerbations from aeroallergen exposure or respiratory virus infections. Aeroallergens and respiratory viruses stimulate toll-like receptor (TLR) signaling, producing oxidative injury and inflammation. Repetitive exacerbations produce complex mucosal adaptations, cell-state changes, and structural remodeling. These structural changes produce substantial morbidity, decrease lung capacity, and impair quality of life. We will review recent systems-level studies that provide fundamental new insights into how repetitive activation of innate signaling pathways produce epigenetic ‘training’ to induce adaptive epithelial responses. Oxidative stress produced downstream of TLR signaling induces transient oxidation of guanine bases in the regulatory regions of inflammatory genes. The epigenetic mark 8-oxoG is bound by a pleiotropic DNA repair enzyme, 8-oxoguanine DNA glycosylase (OGG1), which induces conformational changes in adjacent DNA to recruit the NFκB·bromodomain-containing protein 4 (BRD4) complex. The NFκB·BRD4 complex not only plays a central role in inflammation, but also triggers mesenchymal transition and extracellular matrix remodeling. Small molecule inhibitors of OGG1-8-oxoG binding and BRD4–acetylated histone interaction have been developed. We present studies demonstrating efficacy of these in reducing airway inflammation in preclinical models. Targeting inducible epigenetic reprogramming pathway shows promise for therapeutics in reversing airway remodeling in a variety of chronic airway diseases.

Prenatal exposure to organochlorine compounds and lung function during childhood

INTRODUCTION

Prenatal exposure to organochlorine compounds (OCs) can increase the risk of reported respiratory symptoms in children. It remains unclear whether these compounds can also impact on lung function. We assessed the association between prenatal exposure to OCs and lung function during childhood.

METHODS

We included 1308 mother-child pairs enrolled in a prospective cohort study. Prenatal concentrations of p,p'-dichlorodiphenyltrichloroethane [p,p'-DDT], p,p'-dichlorodiphenyldichloroethylene [p,p'-DDE], hexachlorobenzene [HCB], and seven polychlorinated biphenyls [PCBs] were measured in cord blood. Spirometry was performed in the offspring at ages 4 (n = 636) and 7 years (n = 1192).

RESULTS

More than 80% of samples presented quantifiable levels of p,p'-DDE, HCB, PCB-138, PCB-153, and PCB-180; p,p'-DDE was the compound with the highest median concentrations. At 4 years, prenatal p,p'-DDE exposure was associated with a decrease in forced expiratory volume in 1 s (FEV₁) in all quartiles of exposure (e.g., third quartile [0.23-0.34 ng/mL]: β for FEV₁ -53.61 mL, 95% CI -89.87, -17.35, vs. the lowest). Prenatal p,p'-DDE levels also decreased forced vital capacity (FVC) and FEV₁/FVC, but associations did not reach statistical significance in most exposure quartiles. At 7 years, p,p'-DDE was associated with a decrease in FVC and FEV₁ in only the second quartile of exposure (e.g. β for FEV₁ -36.96 mL, 95% CI -66.22, -7.70, vs. the lowest). Prenatal exposure to HCB was associated with decreased FVC and FEV₁, but in only the second quartile and at 7 years (e.g. [0.07-0.14 ng/mL]: β for FEV₁ -25.79 mL, 95% CI -55.98, 4.39, vs. the lowest). PCBs were not consistently associated with lung function.

CONCLUSION

Prenatal exposure to p,p'-DDE may decrease lung function during childhood, especially FEV₁ and at medium levels of exposure. Further and deeper knowledge on the impact of environmental chemicals during pregnancy on lung development is needed.

Pollen exposure at birth and adolescent lung function, and modification by residential greenness

BACKGROUND

Exposure to high levels of pollen in infancy is a risk factor for allergic respiratory diseases in later childhood, but effects on lung function are not fully understood. We aim to examine associations between grass pollen exposure in the first months of life and lung function at 12 and 18 years, and explore potential modification.

METHODS

Using the Melbourne Atopy Cohort Study, a birth cohort of children with a family history of allergic diseases, we modeled the association between cumulative grass pollen exposure up to 3 months after birth, on FEV₁ , FVC, and FEV₁ /FVC ratio at 12 and 18 years. We also assessed modifying effects of residential greenness levels (derived from satellite imagery), asthma, and early life sensitization to ryegrass.

RESULTS

Grass pollen exposure in the first 7 days was associated with a reduction in FEV₁ (-15.5 mL; 95% CI: -27.6, -3.3 per doubling of pollen count) and FVC (-20.8 mL; -35.4, -6.1) at 12 years, but not at 18 years. Increase in cumulative grass pollen exposure up to 3 months was negatively associated with FVC at 12 and 18. Exposure to high residential greenness modified the association at 18 years.

CONCLUSION

Early exposure to grass pollen was associated with decreased lung function in children and adolescents. Targeted interventions for pollen avoidance strategies that take into account local topography could be implemented alongside other clinical interventions such as immunotherapy.

Opening the Window of Immune Opportunity: Treating Childhood Asthma

Asthma is an increasingly common childhood disease and although most patients can control their symptoms with medication, a proportion experience life-threatening symptoms. The advent of novel biologic therapies represents a giant leap forward for asthma treatment, but efficacy is rarely tested in children. Recent mechanistic work in mice suggests that early life is a key period for immune development and, therefore, allergen sensitization. Although children with severe asthma experience significant comorbidities and are at increased risk for serious diseases such as chronic obstructive pulmonary disease as adults, no specific investigation into tailored treatment for young children with severe asthma exists. Here, we propose how new information regarding early life immunity could be used to inform modified treatments for children.

Paediatric and adult bronchiectasis: Specific management with coexisting asthma, COPD, rheumatological disease and inflammatory bowel disease

Bronchiectasis, conventionally defined as irreversible dilatation of the bronchial tree, is generally suspected on a clinical basis and confirmed by means of chest high-resolution computed tomography. Clinical manifestations, including chronic productive cough and endobronchial suppuration with persistent chest infection and inflammation, may deeply affect quality of life, both in children/adolescents and adults. Despite many cases being idiopathic or post-infectious, a number of specific aetiologies have been traditionally associated with bronchiectasis, such as cystic fibrosis (CF), primary ciliary dyskinesia or immunodeficiencies. Nevertheless, bronchiectasis may also develop in patients with bronchial asthma; chronic obstructive pulmonary disease; and, less commonly, rheumatological disorders and inflammatory bowel diseases. Available literature on the development of bronchiectasis in these conditions and on its management is limited, particularly in children. However, bronchiectasis may complicate the clinical course of the underlying condition at any age, and appropriate management requires an integration of multiple skills in a team of complementary experts to provide the most appropriate care to affected children and adolescents. The present review aims at summarizing the current knowledge and available evidence on the management of bronchiectasis in the other conditions mentioned and focuses on the new therapeutic strategies that are emerging as promising tools for improving patients' quality of life.

Pharmacoproteomics reveal novel protective activity of bromodomain containing 4 inhibitors on vascular homeostasis in TLR3-mediated airway remodeling

Small molecule inhibitors of the epigenetic regulator bromodomain-containing protein 4 (BRD4) are potential therapeutics for viral and allergen-induced airway remodeling. A limitation of their preclinical advancement is the lack of detailed understanding of mechanisms of action and biomarkers of effect. We report a systems-level pharmacoproteomics in a standardized murine model of toll-like receptor TLR3-NFκB/RelA innate inflammation in the absence or presence of a highly selective BRD4 inhibitor (ZL0454) or nonselective bromodomain and extraterminal domain inhibitor (JQ1). Proteomics of bronchoalveolar lavage fluid (BALF) secretome and exosomal proteins from this murine model revealed increased, selective, capillary leak associated with pericyte-myofibroblast transition, a phenomenon blocked by BRD4 inhibitors. BALF proteomics also suggested that ZL0454 better reduced the vascular leakage and extracellular matrix deposition than JQ1. A significant subset of inflammation-mediated remodeling factors was also identified in a mouse model of idiopathic pulmonary fibrosis produced by bleomycin. BALF exosome analysis indicated that BRD4 inhibitors reduced the induction of exosomes enriched in coagulation factors whose presence correlated with interstitial fibrin deposition. Finally, BALF samples from humans with severe asthma demonstrated similar upregulations of ORM2, APCS, SPARCL1, FGA, and FN1, suggesting their potential as biomarkers for early detection of airway remodeling and/or monitoring of therapy response. SIGNIFICANCE: Repetitive and chronic viral upper respiratory tract infections trigger toll-like receptor (TLR)3-NFκB/RelA mediated airway remodeling which is linked to a progressive decline in pulmonary function in patients with asthma and chronic obstructive pulmonary disease. Small molecule inhibitors of the epigenetic regulator bromodomain-containing protein 4 (BRD4) are potential therapeutics for viral and allergen-induced airway remodeling. A limitation of their preclinical advancement is the lack of detailed understanding of mechanisms of action and biomarkers of effect. Our study revealed that the activation of (TLR)3-NFκB/RelA pathway in the lung induced an elevation in coagulation, complement, and platelet factors, indicating the increased vascular leak during airway remodeling. The mechanism of vascular leakage was chronic inflammation-induced pericyte-myofibroblast transition, which was blocked by BRD4 inhibitors. Finally, proteomics analysis of the bronchoalveolar lavage fluid samples from humans with severe asthma demonstrated similar findings that we observed in the animal model.

Plasma cathelicidin and longitudinal lung function in current and former smokers

INTRODUCTION

Cathelicidin (also known as LL-37 in humans) is an antimicrobial peptide secreted by epithelial and immune cells and regulated by vitamin D. The immunological roles of cathelicidin make it a putative biomarker to identify individuals at risk for reduced lung function. The objective of this study is to determine potential independent associations between low plasma cathelicidin and longitudinal lung function in current or former smokers without COPD.

METHODS

In a nested analysis of 308 participants from an observational cohort study, plasma cathelicidin and serum 25-hydroxy-vitamin D measurements were obtained at baseline, years three and five. The independent association between lowest quartile cathelicidin (<35 ng/ml) and forced-expiratory-volume-in-1-second (FEV1) at baseline, six and 18 months from each cathelicidin measurement was assessed with generalized estimating equations after adjusting for age, sex, race, smoking status and intensity. The long-term stability of cathelicidin and relationship with vitamin D was evaluated.

RESULTS

The cohort was 91% African-American, mean age 48.6 years, 32% female, and 81% current smokers. Participants with low cathelicidin were more likely to be female and have lower FEV1. Low cathelicidin was not independently associated with baseline FEV1. There was an independent association between low cathelicidin and reduced FEV1 at six months [-72 ml (95% CI, -140 to -8ml); p = 0.027] and 18 months [-103 ml (95% CI, -180 to -27 ml); p = 0.007]. Cathelicidin was stable over time and not correlated with vitamin D level.

CONCLUSION

In current and former smokers with preserved lung function, low cathelicidin is associated with sustained lung function reductions at six and 18 months, suggesting that cathelicidin may be an informative biomarker to predict persistent lung function disparities among at-risk individuals.

Mechanisms how mucosal innate immunity affects progression of allergic airway disease

INTRODUCTION

Activation of antigen-independent inflammation (a.k.a. the 'innate' immune response (IIR)) plays a complex role in allergic asthma (AA). Although activation of the pulmonary IIR by aerosolized bacterial lipopolysaccharide early in life may be protective of AA, respiratory viral infections promote AA. The mechanisms how the mucosal IIR promotes allergic sensitization, remodeling, and altered epithelial signaling are not understood. Areas covered: This manuscript overviews: 1. Mechanistic studies identifying how allergens and viral patterns activate the mucosal IIR; 2. Research that reveals a major role played by specialized epithelial cells in the bronchiolar-alveolar junction in triggering inflammation and remodeling; 3. Reports linking the mucosal IIR with epithelial cell-state change and barrier disruption; and, 4. Observations relating mesenchymal transition with the expansion of the myofibroblast population. Expert commentary: Luminal allergens and viruses activate TLR signaling in key sentinel cells producing epithelial cell state transition, disrupting epithelial barrier function, and expanding the pulmonary myofibroblast population. These signals are transduced through a common NFκB/RelA -bromodomain containing four (BRD4) pathway, an epigenetic remodeling complex reprogramming the genome. Through this pathway, the mucosal IIR is a major modifier of adaptive immunity, AA and acute exacerbation-induced remodeling.

Lung function trajectories in health and disease

The normal lung function trajectory from birth to death has three phases: a growth phase (from birth to early adulthood), a plateau phase (that lasts for a few years), and a decline phase resulting from physiological lung ageing. Numerous genetic and environmental factors can alter one or more of these phases. Evidence shows that several lung function trajectories exist throughout the life course and, importantly, that some of them are associated with substantial implications for health and disease. Here, we review the evidence, formulate a series of questions, and identify various challenges that need to be addressed to identify potential opportunities to promote respiratory health.

Bronchopulmonary dysplasia: what are its links to COPD?

Emerging evidence suggests that adverse early life events can affect long-term health trajectories throughout life. Preterm birth, in particular, is a significant early life event that affects approximately 10% of live births. Worldwide, prematurity is the number one cause of death in children less than 5 years of age and has been shown to disrupt normal lung development with lasting effects into adult life. Along with impaired lung development, interventions used to support gas exchange and other sequelae of prematurity can lead to the development of bronchopulmonary dysplasia (BPD). BPD is a chronic respiratory disease of infancy characterized by alveolar simplification, small airways disease, and pulmonary vascular changes. Although many survivors of BPD improve with age, survivors of BPD often have chronic lung disease characterized by airflow obstruction and intermittent pulmonary exacerbations. Long-term lung function trajectories as measured by FEV1 can be lower in children and adults with a history BPD. In this review, we discuss the epidemiology and manifestations of BPD and its long-term consequences throughout childhood and into adulthood. Available evidence suggests that disrupted lung development, genetic susceptibility and subsequent environment and infectious events that occur in prenatal and postnatal life likely increase the predisposition of children with BPD to develop early onset chronic obstructive pulmonary disease (COPD). The reviews of this paper are available via the supplemental material section.

Early Identification of Childhood Asthma: The Role of Informatics in an Era of Electronic Health Records

Emerging literature suggests that delayed identification of childhood asthma results in an increased risk of long-term and various morbidities compared to those with timely diagnosis and intervention, and yet this risk is still overlooked. Even when children and adolescents have a history of recurrent asthma-like symptoms and risk factors embedded in their medical records, this information is sometimes overlooked by clinicians at the point of care. Given the rapid adoption of electronic health record (EHR) systems, early identification of childhood asthma can be achieved utilizing (1) asthma ascertainment criteria leveraging relevant clinical information embedded in EHR and (2) innovative informatics approaches such as natural language processing (NLP) algorithms for asthma ascertainment criteria to enable such a strategy. In this review, we discuss literature relevant to this topic and introduce recently published informatics algorithms (criteria-based NLP) as a potential solution to address the current challenge of early identification of childhood asthma.

Efficacy of Novel Highly Specific Bromodomain-Containing Protein 4 Inhibitors in Innate Inflammation-Driven Airway Remodeling

NF-κB/RelA triggers innate inflammation by binding to bromodomain-containing protein 4 (BRD4), an atypical histone acetyltransferase (HAT). Although RelA·BRD4 HAT mediates acute neutrophilic inflammation, its role in chronic and functional airway remodeling is not known. We observed that BRD4 is required for Toll-like receptor 3 (TLR3)-mediated mesenchymal transition, a cell-state change that is characteristic of remodeling. We therefore tested two novel highly selective BRD4 inhibitors, ZL0420 and ZL0454, for their effects on chronic airway remodeling produced by repetitive TLR3 agonist challenges, and compared their efficacy with that of two nonselective bromodomain and extraterminal (BET) protein inhibitors, JQ1 and RVX208. We observed that ZL0420 and ZL0454 more potently reduced polyinosinic:polycytidylic acid-induced weight loss and fibrosis as assessed by microcomputed tomography and second harmonic generation microscopy. These measures correlated with the collagen deposition observed in histopathology. Importantly, the ZL inhibitors were more effective than the nonselective BET inhibitors at equivalent doses. The ZL inhibitors had significant effects on lung physiology, reversing TLR3-associated airway hyperresponsiveness and increasing lung compliance in vivo. At the molecular level, ZL inhibitors reduced elaboration of the transforming growth factor-β-induced growth program, thereby preventing mucosal mesenchymal transition and disrupting BRD4 HAT activity and complex formation with RelA. We also observed that ZL0454 treatment blocked polyinosinic:polycytidylic acid-associated expansion of the α-SMA1⁺/COL1A⁺ myofibroblast population and prevented myofibroblast transition in a coculture system. We conclude that 1) BRD4 is a central effector of the mesenchymal transition that results in paracrine activation of myofibroblasts, mechanistically linking innate inflammation to airway hyperresponsiveness and fibrosis, and 2) highly selective BRD4 inhibitors may be effective in reversing the effects of repetitive airway viral infections on innate inflammation-mediated remodeling.

Lung Function of Children at Three Sites of Varying Ambient Air Pollution Levels in Uganda: A Cross Sectional Comparative Study

Air pollution is a major cause of sub-optimal lung function and lung diseases in childhood and adulthood. In this study we compared the lung function (measured by spirometry) of 537 Ugandan children, mean age 11.1 years in sites with high (Kampala and Jinja) and low (Buwenge) ambient air pollution levels, based on the concentrations of particulate matter smaller than 2.5 micrometres in diameter (PM_2.5). Factors associated with lung function were explored in a multiple linear regression model. PM_2.5 level in Kampala, Jinja and Buwenge were 177.5 µg/m³, 96.3 µg/m³ and 31.4 µg/m³ respectively (p = 0.0000). Respectively mean forced vital capacity as % of predicted (FVC%), forced expiratory volume in one second as % of predicted (FEV₁%) and forced expiratory flow 25⁻75% as % of predicted (FEF_25⁻75%) of children in high ambient air pollution sites (Kampala and Jinja) vs. those in the low ambient air pollution site (Buwenge subcounty) were: FVC% (101.4%, vs. 104.0%, p = 0.043), FEV₁% (93.9% vs. 98.0, p = 0.001) and FEF_25⁻75% (87.8 vs. 94.0, p = 0.002). The proportions of children whose %predicted parameters were less than 80% predicted (abnormal) were higher among children living in high ambient air pollution than those living in lower low ambient air pollutions areas with the exception of FVC%; high vs. low: FEV1 < 80%, %predicted (12.0% vs. 5.3%, p = 0.021) and FEF_25⁻75 < 80%, %predicted (37.7% vs. 29.3%, p = 0.052) Factors associated with lung function were (coefficient, p-value): FVC% urban residence (-3.87, p = 0.004), current cough (-2.65, p = 0.048), underweight (-6.62, p = 0.000), and overweight (11.15, p = 0.000); FEV₁% underweight (-6.54, p = 0.000) and FEF_25⁻75% urban residence (-8.67, p = 0.030) and exposure to biomass smoke (-7.48, p = 0.027). Children in study sites with high ambient air pollution had lower lung function than those in sites with low ambient air pollution. Urban residence, underweight, exposure to biomass smoke and cough were associated with lower lung function.

Therapeutic targets for inflammation-mediated airway remodeling in chronic lung disease

INTRODUCTION

Acute exacerbations of chronic lung disease account for substantial morbidity and health costs. Repeated inflammatory episodes and attendant bronchoconstriction cause structural remodeling of the airway. Remodeling is a multicellular response to mucosal injury that results in epithelial cell-state changes, enhanced extracellular deposition, and expansion of pro-fibrotic myofibroblast populations. Areas covered: This manuscript overviews mechanistic studies identifying key sentinel cell populations in the airway and how pattern recognition signaling induces maladaptive mucosal changes and airway remodeling. Studies elucidating how NFκB couples with an atypical histone acetyltransferase, bromodomain-containing protein 4 (BRD4) that reprograms mucosal fibrogenic responses, are described. The approaches to development and characterization of selective inhibitors of epigenetic reprogramming on innate inflammation and structural remodeling in preclinical models are detailed. Expert commentary: Bronchiolar cells derived from Scgb1a1-expressing progenitors function as major sentinel cells of the airway, responsible for initiating antiviral and aeroallergen responses. In these sentinel cells, activation of innate inflammation is coupled to neutrophilic recruitment, mesenchymal transition and myofibroblast expansion. Therapeutics targeting the NFkB-BRD4 may be efficacious in reducing pathological effects of acute exacerbations in chronic lung disease.

Predictors of Asthma/COPD Overlap in FDNY Firefighters With World Trade Center Dust Exposure: A Longitudinal Study

BACKGROUND

Previously healthy firefighters with World Trade Center (WTC) dust exposure developed airway disease. Risk factors for irritant-associated asthma/COPD overlap are poorly defined.

METHODS

This study included 2,137 WTC-exposed firefighters who underwent a clinically indicated bronchodilator pulmonary function test (BD-PFT) between 9/11/2001 and 9/10/2017. A post-BD FEV₁ increase of > 12% and 200 mL from baseline defined asthma, and a post-BD FEV₁/FVC ratio < 0.7 identified COPD cases. Participants who met both criteria had asthma/COPD overlap. Eosinophil levels were measured on screening blood tests performed shortly after 9/11/2001 and prior to BD-PFT; a subgroup of participants also had serum IgE and 21 cytokines measured (n = 215). Marginal Cox regression models for multiple events assessed the associations of eosinophil levels or serum biomarkers with subsequent diagnosis, with age, race, smoking, WTC exposure, first post-9/11 FEV₁/FVC ratio, and BMI included as covariates.

RESULTS

BD-PFT diagnosed asthma/COPD overlap in 99 subjects (4.6%), isolated-asthma in 202 (9.5%), and isolated-COPD in 215 (10.1%). Eosinophil concentration ≥ 300 cells/μL was associated with increased risk of asthma/COPD overlap (hazard ratio [HR], 1.85; 95% CI, 1.16-2.95) but not with isolated-asthma or isolated-COPD. Serum IL-4 also predicted asthma/COPD overlap (HR, 1.51 per doubling of cytokine concentration; 95% CI, 1.17-1.95). Greater IL-21 concentration was associated with both isolated-asthma and isolated-COPD (HRs of 1.73 [95% CI, 1.27-2.35] and 2.06 [95% CI, 1.31-3.23], respectively).

CONCLUSIONS

In WTC-exposed firefighters, elevated blood eosinophil and IL-4 levels are associated with subsequent asthma/COPD overlap. Disease-specific T-helper cell type 2 biomarkers present years before diagnosis suggest patient-intrinsic predisposition to irritant-associated asthma/COPD overlap.

EARLY versus MILD Chronic Obstructive Pulmonary Disease (COPD)

Chronic Obstructive Pulmonary Disease (COPD) is very a common, with great morbidity and mortality, disease. Since the beginning of the disease cannot be detected with precision and by using only FEV1 to monitor the evolution of the disease, the Natural History of COPD is rather obscure and sometimes controversial. Therefore, the terms EARLY COPD and MILD COPD have been used indistinguishably in the medical literature. In this review we discuss the two terms trying to clarify some of the definition issues, starting with a synopsis of the Naturel History of the disease. We recommend to use the term EARLY COPD for the pre-clinical stage of the disease (stage 0) and the term MILD COPD when the diagnosis is confirmed by spirometry and FEV1 is above 80% predicted. However, COPD is a complex disease and spirometric evaluation alone (MILD COPD, stage I), cannot fully describe the clinical status of the patient. We conclude that biomarkers to detect the starting point and been able to follow the natural history of the disease more accurately, beyond FEV, are urgently needed.

Prediction models for the development of COPD: a systematic review

Early identification of people at risk of developing COPD is crucial for implementing preventive strategies. We aimed to systematically review and assess the performance of all published models that predicted development of COPD. A search was conducted to identify studies that developed a prediction model for COPD development. The Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies was followed when extracting data and appraising the selected studies. Of the 4,481 records identified, 30 articles were selected for full-text review, and only four of these were eligible to be included in the review. The only consistent predictor across all four models was a measure of smoking. Sex and age were used in most models; however, other factors varied widely. Two of the models had good ability to discriminate between people who were correctly or incorrectly classified as at risk of developing COPD. Overall none of the models were particularly useful in accurately predicting future risk of COPD, nor were they good at ruling out future risk of COPD. Further studies are needed to develop new prediction models and robustly validate them in external cohorts.

Clinical characterization of children with resistant airflow obstruction, a multicenter study

OBJECTIVE

To characterize a cohort of children with airflow limitation resistant to bronchodilator (BD) therapy.

METHODS

Pulmonary function tests performed in children 6-17 years of age at 15 centers in a clinical research consortium were screened for resistant airflow limitation, defined as a post-BD FEV₁ and/or an FEV₁/FVC less than the lower limits of normal. Demographic and clinical data were analyzed for associations with pulmonary function.

RESULTS

582 children were identified. Median age was 13 years (IQR: 11, 16), 60% were males; 62% were Caucasian, 28% were African-American; 19% were obese; 32% were born prematurely and 21% exposed to second hand smoke. Pulmonary diagnoses included asthma (93%), prior significant pneumonia (28%), and bronchiectasis (5%). 65% reported allergic rhinitis, and 11% chronic sinusitis. Subjects without a history of asthma had significantly lower post-BD FEV₁% predicted (p = 0.008). Subjects without allergic rhinitis had lower post-BD FEV₁% predicted (p = 0.003). Children with allergic rhinitis, male sex, obesity and Black race had better pulmonary function post-BD. There was lower pulmonary function in children after age 11 years without a history of allergic rhinitis, as compared to those with a history of allergic rhinitis.

CONCLUSIONS

The most prevalent diagnosis in children with BD-resistant airflow limitation is asthma. Allergic rhinitis and premature birth are common co-morbidities. Children without a history of asthma, as well as those with asthma but no allergic rhinitis, had lower pulmonary function. Children with BD-resistant airflow limitation may represent a sub-group of children with persistent obstruction and high risk for life-long airway disease.

Chronic airway obstruction in a population-based adult asthma cohort: Prevalence, incidence and prognostic factors

BACKGROUND

Asthma and COPD may overlap (ACO) but information about incidence and risk factors are lacking. This study aimed to estimate prevalence, incidence and risk factors of chronic airway obstruction (CAO) in a population-based adult asthma cohort.

METHODS

During 1986-2001 a large population-based asthma cohort was identified (n = 2055, 19-72y). Subsamples have participated in clinical follow-ups during the subsequent years. The entire cohort was invited to a clinical follow-up including interview, spirometry, and blood sampling in 2012-2014 when n = 983 subjects performed adequate spirometry. CAO was defined as post-bronchodilator FEV₁/FVC<0.7.

RESULTS

At study entry, asthmatics with prevalent CAO (11.4%) reported more respiratory symptoms, asthma medication use, and ischemic heart disease than asthmatics without CAO (asthma only). Subjects who developed CAO during follow-up (17.6%; incidence rate of 16/1000/year) had a more rapid FEV₁ decline and higher levels of neutrophils than asthma only. Smoking, older age and male sex were independently associated with increased risk for both prevalent and incident CAO, while obesity had a protective effect.

CONCLUSIONS

In this prospective adult asthma cohort, the majority did not develop CAO. Smoking, older age and male sex were risk factors for prevalent and incident CAO, similar to risk factors described for COPD in the general population.

Asthma Is a Risk Factor for Respiratory Exacerbations Without Increased Rate of Lung Function Decline: Five-Year Follow-up in Adult Smokers From the COPDGene Study

BACKGROUND

Previous investigations in adult smokers from the COPDGene Study have shown that early-life respiratory disease is associated with reduced lung function, COPD, and airway thickening. Using 5-year follow-up data, we assessed disease progression in subjects who had experienced early-life respiratory disease. We hypothesized that there are alternative pathways to reaching reduced FEV₁ and that subjects who had childhood pneumonia, childhood asthma, or asthma-COPD overlap (ACO) would have less lung function decline than subjects without these conditions.

METHODS

Subjects returning for 5-year follow-up were assessed. Childhood pneumonia was defined by self-reported pneumonia at < 16 years. Childhood asthma was defined as self-reported asthma diagnosed by a health professional at < 16 years. ACO was defined as subjects with COPD who self-reported asthma diagnosed by a health-professional at ≤ 40 years. Smokers with and those without these early-life respiratory diseases were compared on measures of disease progression.

RESULTS

Follow-up data from 4,915 subjects were examined, including 407 subjects who had childhood pneumonia, 323 subjects who had childhood asthma, and 242 subjects with ACO. History of childhood asthma or ACO was associated with an increased exacerbation frequency (childhood asthma, P < .001; ACO, P = .006) and odds of severe exacerbations (childhood asthma, OR, 1.41; ACO, OR, 1.42). History of childhood pneumonia was associated with increased exacerbations in subjects with COPD (absolute difference [β], 0.17; P = .04). None of these early-life respiratory diseases were associated with an increased rate of lung function decline or progression on CT scans.

CONCLUSIONS

Subjects who had early-life asthma are at increased risk of developing COPD and of having more active disease with more frequent and severe respiratory exacerbations without an increased rate of lung function decline over a 5-year period.

TRIAL REGISTRY

ClinicalTrials.gov; No. NCT00608764; https://clinicaltrials.gov.

Natural history of COPD: gaps and opportunities

Understanding the natural history of a disease is as important as knowing its cause(s) for effective disease prevention and treatment. Yet, our current understanding of the natural history of chronic obstructive pulmonary disease (COPD) is incomplete and often controversial. This article discusses the current gaps, and hence opportunities for research, in this field. In particular, it discusses the following six specific questions. 1) Is COPD a “single” disease? 2) Is COPD “only” a lung disease? 3) When does COPD begin or what is “early” COPD? 4) How does COPD “progress”? 5) How do we assess disease “severity”? 6) Can COPD be prevented (beyond smoking cessation) or its course be modified once detected?

A new review series starts in ERJ Open Research: “Gaps in our understanding of COPD”http://ow.ly/CFSD30gpXs8

Lung function in early adulthood and health in later life: a transgenerational cohort analysis

BACKGROUND

Early life events can affect health in later life. We hypothesised that low lung function (FEV₁ <80% predicted) in early adulthood (25-40 years) is associated with higher prevalence and earlier incidence of respiratory, cardiovascular, and metabolic abnormalities, and premature death.

METHODS

In this cohort analysis, we tested this hypothesis using data from the Framingham Offspring Cohort (FOC) and validated our observations in CARDIA (an independent cohort) and GenIII (which includes the direct descendants of FOC participants). These were three general population cohorts that included men and women, who were regularly and prospectively followed up to collect extensive clinical, physiological, biological, and imaging information. Main outcomes were prevalence (in early adulthood) and incidence (during follow-up) of comorbidity, and all-cause mortality. χ² test, unpaired t test, Fisher's exact test, and Cox proportional hazards models were used for data analysis. Differential dropout rates during follow-up were regarded as a potential source of bias.

FINDINGS

We found that 111 (10%) of 1161 participants in FOC, 338 (13%) of 2648 participants in CARDIA, and 71 (4%) of 1912 participants in GenIII had FEV₁ of less than 80% predicted at the age of 25-40 years. These individuals also had higher prevalence of respiratory, cardiovascular, and metabolic abnormalities in early adulthood; higher and earlier (about a decade) incidence of comorbidities during follow-up (39 years vs 47 years in FOC; 30 years vs 37 years in CARDIA, p<0·0001); and higher all-cause mortality than individuals with normal lung function in early adulthood (in FOC, hazard ratio 2·3 [95% CI 1·4-3·7], p=0·001), which was independent of, but additive with, cumulative smoking exposure. In GenIII, we observed that individuals with at least one parent stratified as having low lung function in early adulthood in FOC (n=115) had lower FEV₁ in early adulthood (10% had FEV₁ of less than 80% predicted; this proportion was 3% in those with both parents classified as normal in FOC [n=248]; p<0·0001); and early adulthood FEV₁ of GenIII participants was related (R²=0·28, p<0·0001) to FOC parents' average FEV₁ in early adulthood.

INTERPRETATION

Low peak lung function in early adulthood is common in the general population and could identify a group of individuals at risk of early comorbidities and premature death.

FUNDING

Fondo de Investigacion Sanitaria, Sociedad Española de Neumologia y Cirurgia Torácica, Formació Personal Investigador, Agencia de Gestió d'Ajuts de Recerca 2016, and AstraZeneca Foundation Young Researcher Award.

Innate Immunity to Respiratory Infection in Early Life

Early life is a period of particular susceptibility to respiratory infections and symptoms are frequently more severe in infants than in adults. The neonatal immune system is generally held to be deficient in most compartments; responses to innate stimuli are weak, antigen-presenting cells have poor immunostimulatory activity and adaptive lymphocyte responses are limited, leading to poor immune memory and ineffective vaccine responses. For mucosal surfaces such as the lung, which is continuously exposed to airborne antigen and to potential pathogenic invasion, the ability to discriminate between harmless and potentially dangerous antigens is essential, to prevent inflammation that could lead to loss of gaseous exchange and damage to the developing lung tissue. We have only recently begun to define the differences in respiratory immunity in early life and its environmental and developmental influences. The innate immune system may be of relatively greater importance than the adaptive immune system in the neonatal and infant period than later in life, as it does not require specific antigenic experience. A better understanding of what constitutes protective innate immunity in the respiratory tract in this age group and the factors that influence its development should allow us to predict why certain infants are vulnerable to severe respiratory infections, design treatments to accelerate the development of protective immunity, and design age specific adjuvants to better boost immunity to infection in the lung.

The Relationship Between Tobacco Smoke Exposure and Airflow Obstruction in US Children: Analysis of the National Health and Nutrition Examination Survey (2007-2012)

BACKGROUND

It has been difficult to determine the individual impact of prenatal and postnatal tobacco smoke exposure (TSE) on childhood lung function, as children are often exposed to both.

OBJECTIVE

The goal of this study was to determine the association between current TSE and airflow obstruction while adjusting for self-reported prenatal TSE.

METHODS

Children aged 6 to 11 years who participated in the National Health and Nutrition Examination Survey (2007-2012) who had serum cotinine levels measured and spirometry performed were included. Logistic regression was used to determine the association between log-transformed serum cotinine level and airflow obstruction while adjusting for confounders; the analysis was then stratified according to asthma status. The final model included both log-transformed serum cotinine level and prenatal exposure as covariates.

RESULTS

The sample consisted of 2,070 children; 9.6% had airflow obstruction. The association between cotinine levels and airflow obstruction was significant in an unadjusted analysis (OR, 1.12 [95% CI, 1.02-1.23]). In the multivariate analysis with both exposures included as covariates, serum cotinine level was not significantly associated with airflow obstruction (OR_adj, 1.07 [95% CI, 0.94-1.21]), and no association was seen in children with asthma and nonasthmatic children. Prenatal smoking was associated with airflow obstruction in children with asthma (OR_adj, 2.51 [95% CI, 1.08-5.79]) but not in nonasthmatic children (OR_adj, 1.08 [95% CI, 0.53-2.18]).

CONCLUSIONS

Current TSE was not independently associated with airflow obstruction in school-aged children. Prenatal TSE was associated with airflow obstruction in children with asthma. Repeated studies into potential mediators and confounders of this relationship are needed.

Wood Stove Pollution in the Developed World: A Case to Raise Awareness Among Pediatricians

Use of wood for residential heating is regaining popularity in developed countries. Currently, over 11 million US homes are heated with a wood stove. Although wood stoves reduce heating costs, wood smoke may adversely impact child health through the emission of gaseous and particulate air pollutants. Our purpose is to raise awareness of this environmental health issue among pediatricians. To summarize the state of the science, we performed a narrative review of articles published in PubMed and Web of Science. We identified 36 studies in developed countries that reported associations of household wood stove use and/or community wood smoke exposure with pediatric health outcomes. Studies primarily investigated respiratory outcomes, with no evaluation of cardiometabolic or neurocognitive health. Studies found community wood smoke exposure to be consistently associated with adverse pediatric respiratory health. Household wood stove use was less consistently associated with respiratory outcomes. However, studies of household wood stoves always relied on participant self-report of wood stove use, while studies of community wood smoke generally assessed air pollution exposure directly and more precisely in larger study populations. In most studies, important potential confounders, such as markers of socioeconomic status, were unaccounted for and may have biased results. We conclude that studies with improved exposure assessment, that measure and account for confounding, and that consider non-respiratory outcomes are needed. While awaiting additional data, pediatricians can refer patients to precautionary measures recommended by the US Environmental Protection Agency (EPA) to mitigate exposure. These include replacing old appliances with EPA-certified stoves, properly maintaining the stove, and using only dry, well-seasoned wood. In addition, several studies have shown mechanical air filters to effectively reduce wood stove pollution exposure in affected homes and communities.

Recent advances in understanding lung function development

Recent years have witnessed critical contributions to our understanding of the determinants and long-term implications of lung function development. In this article, we review studies that have contributed to advances in understanding lung function development and its critical importance for lung health into adult life. In particular, we have focused on early life determinants that include genetic factors, perinatal events, environmental exposures, lifestyle, infancy lower respiratory tract infections, and persistent asthma phenotypes. Longitudinal studies have conclusively demonstrated that lung function deficits that are established by school age may track into adult life and increase the risk of adult lung obstructive diseases, such as chronic obstructive pulmonary disease. Furthermore, these contributions have provided initial evidence in support of a direct influence by early life events on an accelerated decline of lung function and an increased susceptibility to its environmental determinants well into adult life. As such, we argue that future health-care programs based on precision medicine approaches that integrate deep phenotyping with tailored medication and advice to patients should also foster optimal lung function growth to be fully effective.