Circulating biomarkers of airflow limitation across the life span.

BACKGROUND: Airflow limitation is a hallmark of chronic obstructive pulmonary disease, which can develop through different lung function trajectories across the life span. There is a need for longitudinal studies aimed at identifying circulating biomarkers of airflow limitation across different stages of life. OBJECTIVES: This study sought to identify a signature of serum proteins associated with airflow limitation and evaluate their relation to lung function longitudinally in adults and children. METHODS: This study used data from 3 adult cohorts (TESAOD [Tucson Epidemiological Study of Airway Obstructive Disease], SAPALDIA [Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults], LSC [Lovelace Smoker Cohort]) and 1 birth cohort (TCRS [Tucson Children's Respiratory Study]) (N = 1940). In TESAOD, among 46 circulating proteins, we identified those associated with FEV1/forced vital capacity (FVC) percent (%) predicted levels and generated a score based on the sum of their z-scores. Cross-sectional analyses were used to test the score for association with concomitant lung function. Longitudinal analyses were used to test the score for association with subsequent lung function growth in childhood and decline in adult life. RESULTS: After false discovery rate adjustment, serum levels of 5 proteins (HP, carcinoembryonic antigen, ICAM1, CRP, TIMP1) were associated with percent predicted levels of FEV1/FVC and FEV1 in TESAOD. In cross-sectional multivariate analyses the 5-biomarker score was associated with FEV1 % predicted in all adult cohorts (meta-analyzed FEV1 decrease for 1-SD score increase: -2.9%; 95% CI: -3.9%, -1.9%; P = 2.4 × 10-16). In multivariate longitudinal analyses, the biomarker score at 6 years of age was inversely associated with FEV1 and FEV1/FVC levels attained by young adult life (P = .02 and .005, respectively). In adults, persistently high levels of the biomarker score were associated with subsequent accelerated decline of FEV1 and FEV1/FVC (P = .01 and .001). CONCLUSIONS: A signature of 5 circulating biomarkers of airflow limitation was associated with both impaired lung function growth in childhood and accelerated lung function decline in adult life, indicating that these proteins may be involved in multiple lung function trajectories leading to chronic obstructive pulmonary disease.

Spirometric patterns in young and middle-aged adults: a 20-year European study.

BACKGROUND: Understanding the natural history of abnormal spirometric patterns at different stages of life is critical to identify and optimise preventive strategies. We aimed to describe characteristics and risk factors of restrictive and obstructive spirometric patterns occurring before 40 years (young onset) and between 40 and 61 years (mid-adult onset). METHODS: We used data from the population-based cohort of the European Community Respiratory Health Survey (ECRHS). Prebronchodilator forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were assessed longitudinally at baseline (ECRHS1, 1993-1994) and again 20 years later (ECRHS3, 2010-2013). Spirometry patterns were defined as: restrictive if FEV1/FVC≥LLN and FVC<10th percentile, obstructive if FEV1/FVC

Distinction between rhinitis alone and rhinitis with asthma using interactomics.

The concept of "one-airway-one-disease", coined over 20 years ago, may be an over-simplification of the links between allergic diseases. Genomic studies suggest that rhinitis alone and rhinitis with asthma are operated by distinct pathways. In this MeDALL (Mechanisms of the Development of Allergy) study, we leveraged the information of the human interactome to distinguish the molecular mechanisms associated with two phenotypes of allergic rhinitis: rhinitis alone and rhinitis in multimorbidity with asthma. We observed significant differences in the topology of the interactomes and in the pathways associated to each phenotype. In rhinitis alone, identified pathways included cell cycle, cytokine signalling, developmental biology, immune system, metabolism of proteins and signal transduction. In rhinitis and asthma multimorbidity, most pathways were related to signal transduction. The remaining few were related to cytokine signalling, immune system or developmental biology. Toll-like receptors and IL-17-mediated signalling were identified in rhinitis alone, while IL-33 was identified in rhinitis in multimorbidity. On the other hand, few pathways were associated with both phenotypes, most being associated with signal transduction pathways including estrogen-stimulated signalling. The only immune system pathway was FceRI-mediated MAPK activation. In conclusion, our findings suggest that rhinitis alone and rhinitis and asthma multimorbidity should be considered as two distinct diseases.

The Impact of CC16 on Pulmonary Epithelial-Driven Host Responses during Mycoplasma pneumoniae Infection in Mouse Tracheal Epithelial Cells.

Club Cell Secretory Protein (CC16) plays many protective roles within the lung; however, the complete biological functions, especially regarding the pulmonary epithelium during infection, remain undefined. We have previously shown that CC16-deficient (CC16-/-) mouse tracheal epithelial cells (MTECs) have enhanced Mp burden compared to CC16-sufficient (WT) MTECs; therefore, in this study, we wanted to further define how the pulmonary epithelium responds to infection in the context of CC16 deficiency. Using mass spectrometry and quantitative proteomics to analyze proteins secreted apically from MTECs grown at an air-liquid interface, we investigated the protective effects that CC16 elicits within the pulmonary epithelium during Mycoplasma pneumoniae (Mp) infection. When challenged with Mp, WT MTECs have an overall reduction in apical protein secretion, whereas CC16-/- MTECs have increased apical protein secretion compared to their unchallenged controls. Following Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) assessment, many of the proteins upregulated from CC16-/- MTECS (unchallenged and during Mp infection) were related to airway remodeling, which were not observed by WT MTECs. These findings suggest that CC16 may be important in providing protection within the pulmonary epithelium during respiratory infection with Mp, which is the major causative agent of community-acquired pneumoniae.

Cytomegalovirus serology in young to mid-adult life and decline of lung function.

INTRODUCTION: Cytomegalovirus (CMV) seropositivity has been recently linked to severity and progression of asthma, cystic fibrosis, and chronic obstructive pulmonary disease (COPD). To date, no longitudinal study has addressed the relation of CMV serology to levels and decline of lung function in the general adult population. METHODS: We evaluated 403 participants from the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD) who at enrollment were aged 28-55 years and completed lung function tests. During follow-up, the 403 participants completed on average 7.2 lung function tests per subject for a total of 2908 observations over a mean period of 14.7 years. We tested CMV serology in serum samples from enrollment and categorized participants into low, medium, and high CMV serology based on tertiles. The relation of CMV serology at enrollment to lung function levels and decline during follow-up was tested in multivariate random coefficients models. RESULTS: After full adjustment, participants in the highest CMV serology tertile had faster declines of forced expiratory volume in 1 s (FEV1 ) and FEV1 /forced vital capacity (FVC) compared with subjects in the lowest tertile (by -7.9 ml/year 95% confidence interval [-13.9 ml/year, -1.93 ml/year], and by -0.13%/year [-0.23%/year, -0.026%/year], respectively). These CMV effects were additive with those of cigarette smoking. No associations were found between CMV serology and FVC, indicating specific effects of CMV seropositivity on airflow limitation. CONCLUSION: High CMV serology in young to mid-adult life may be linked to increased COPD risk through an accelerated decline of lung function.

Low CC16 mRNA Expression Levels in Bronchial Epithelial Cells Are Associated with Asthma Severity.

Rationale: CC16 is a protein mainly produced by nonciliated bronchial epithelial cells (BECs) that participates in host defense. Reduced CC16 protein concentrations in BAL and serum are associated with asthma susceptibility. Objectives: Few studies have investigated the relationship between CC16 and asthma progression, and none has focused on BECs. In this study, we sought to determine if CC16 mRNA expression levels in BECs are associated with asthma severity. Methods: Association analyses between CC16 mRNA expression levels in BECs (242 asthmatics and 69 control subjects) and asthma-related phenotypes in Severe Asthma Research Program were performed using a generalized linear model. Measurements and Main Results: Low CC16 mRNA expression levels in BECs were significantly associated with asthma susceptibility and asthma severity, high systemic corticosteroids use, high retrospective and prospective asthma exacerbations, and low pulmonary function. Low CC16 mRNA expression levels were significantly associated with high T2 inflammation biomarkers (fractional exhaled nitric oxide and sputum eosinophils). CC16 mRNA expression levels were negatively correlated with expression levels of Th2 genes (IL1RL1, POSTN, SERPINB2, CLCA1, NOS2, and MUC5AC) and positively correlated with expression levels of Th1 and inflammation genes (IL12A and MUC5B). A combination of two nontraditional T2 biomarkers (CC16 and IL-6) revealed four asthma endotypes with different characteristics of T2 inflammation, obesity, and asthma severity. Conclusions: Our findings indicate that low CC16 mRNA expression levels in BECs are associated with asthma susceptibility, severity, and exacerbations, partially through immunomodulation of T2 inflammation. CC16 is a potential nontraditional T2 biomarker for asthma development and progression.

Club cell secretory protein and lung function in children with cystic fibrosis.

BACKGROUND: Club cell secretory protein (CC16) exerts anti-inflammatory functions in lung disease. We sought to determine the relation of serum CC16 deficits and genetic variants that control serum CC16 to lung function among children with cystic fibrosis (CF). METHODS: We used longitudinal data from CF children (EPIC Study) with no positive cultures for Pseudomonas aeruginosa prior to enrollment. Circulating levels of CC16 and an inflammatory score (generated from CRP, SAA, calprotectin, G-CSF) were compared between participants with the lowest and highest FEV1 levels in adolescence (LLF and HLF groups, respectively; N = 130-per-group). Single nucleotide variants (SNVs) in the SCGB1A1, EHF-APIP loci were tested for association with circulating CC16 and with decline of FEV1 and FEV1/FVC% predicted levels between ages 7-16 using mixed models. RESULTS: Compared with the HLF group, the LLF group had lower levels of CC16 (geometric means: 8.2 vs 6.5 ng/ml, respectively; p = 0.0002) and higher levels of the normalized inflammatory score (-0.21 vs 0.21, p = 0.0007). Participants in the lowest CC16 and highest inflammation tertile had the highest odds for having LLF (p<0.0001 for comparison with participants in the highest CC16 and lowest inflammation tertile). Among seven SNVs associated with circulating CC16, the top SNV rs3741240 was associated with decline of FEV1/FVC and, marginally, FEV1 (p = 0.003 and 0.025, respectively; N = 611 participants, 20,801 lung function observations). CONCLUSIONS: Serum CC16 deficits are strongly associated with severity of CF lung disease and their effects are additive with systemic inflammation. The rs3741240 A allele is associated with low circulating CC16 and, possibly, accelerated lung function decline in CF.

Epithelial cell responses to rhinovirus identify an early-life-onset asthma phenotype in adults.

BACKGROUND: The study of pathogenic mechanisms in adult asthma is often marred by a lack of precise information about the natural history of the disease. Children who have persistent wheezing (PW) during the first 6 years of life and whose symptoms start before age 3 years (PW+) are much more likely to have wheezing illnesses due to rhinovirus (RV) in infancy and to have asthma into adult life than are those who do not have PW (PW-). OBJECTIVE: Our aim was to determine whether nasal epithelial cells from PW+ asthmatic adults as compared with cells from PW- asthmatic adults show distinct biomechanistic processes activated by RV exposure. METHODS: Air-liquid interface cultures derived from nasal epithelial cells of 36-year old participants with active asthma with and without a history of PW in childhood (10 PW+ participants and 20 PW- participants) from the Tucson Children's Respiratory Study were challenged with a human RV-A strain (RV-A16) or control, and their RNA was sequenced. RESULTS: A total of 35 differentially expressed genes involved in extracellular remodeling and angiogenesis distinguished the PW+ group from the PW- group at baseline and after RV-A stimulation. Notably, 22 transcriptomic pathways showed PW-by-RV interactions; the pathways were invariably overactivated in PW+ patients, and were involved in Toll-like receptor- and cytokine-mediated responses, remodeling, and angiogenic processes. CONCLUSIONS: Asthmatic adults with a history of persistent wheeze in the first 6 years of life have specific biomolecular alterations in response to RV-A that are not present in patients without such a history. Targeting these mechanisms may slow the progression of asthma in these patients.

Associations between pre- and postnatal exposure to air pollution and lung health in children and assessment of CC16 as a potential mediator.

BACKGROUND: Early life exposure to air pollution can affect lung health. Previous studies have not assessed the implications of both pre- and postnatal exposure to air pollutants on lung function at repeated ages during childhood. In addition, there is the need to identify potential mediators of such effect. OBJECTIVES: To longitudinally assess the association between pre- and postnatal air pollution exposure and lung function during childhood. We also aimed to explore the role of Club cell secretory protein (CC16) as a potential mediator in this association. METHODOLOGY: We included 487 mother-child pairs from the INMA (INfancia y Medio Ambiente) Sabadell birth cohort, recruited between 2004 and 2006. Air pollution exposure was estimated for pregnancy, pre-school age, and school-age using temporally adjusted land use regression (LUR) modelling. Lung function was measured at ages 4, 7, 9 and 11 by spirometry. At age 4, serum CC16 levels were determined in 287 children. Multivariable linear regression models and linear mixed modelling were applied, while considering potential confounders. RESULTS: Prenatal exposure to Particulate Matter (PM)10 and PMcoarse had the most consistent associations with reduced lung function in cross-sectional models. Associations with postnatal exposure were less consistent. Increasing CC16 levels at 4 years were associated with an increase in FEF25-75 (ß = 120.4 mL, 95% CI: 6.30, 234.5) from 4 to 11 years of age. No statistically significant associations were found between pre- or postnatal air pollution and CC16 at age 4. CONCLUSION: Increasing levels of air pollution exposure, particularly prenatal PM10 and PMcoarse exposure, were associated with a reduction in lung function. We were not able to confirm our hypothesis on the mediation role of CC16 in this association, however our results encourage further exploration of this possibility in future studies.

CC16 Deficiency in the Context of Early-Life Mycoplasma pneumoniae Infection Results in Augmented Airway Responses in Adult Mice.

Studies have shown that club cell secretory protein (CC16) plays important protective roles in the lungs, yet its complete biological functions are unclear. We devised a translational mouse model in order to investigate the impact of early life infections, in the context of CC16 deficiency, on lung function in adult mice. CC16 sufficient (WT) and deficient (CC16-/-) mice were infected with Mycoplasma pneumoniae (Mp) as weanlings and assessed as adults (early life infection model; ELIM) and compared to adult mice infected for only 3 days (adult infection model; AIM). CC16-/- Mp-infected mice had significantly increased airway hyperresponsiveness (AHR) in both models compared to WT mice. However, CC16-/- mice infected in early life (ELIM) displayed significantly increased AHR compared to CC16-/- mice infected in adulthood (AIM). In stark contrast, lung function in ELIM WT mice returned to levels similar to saline-treated controls. While WT mice cleared Mp infection in the ELIM, CC16-/- mice remained colonized with Mp throughout the model, which likely contributed to increased airway remodeling and persistence of Muc5ac expression. When CC16-/- mouse tracheal epithelial cells (MTECs) were infected with Mp, increased Mp colonization and collagen gene expression were also detected compared to WT cells, suggesting that CC16 plays a protective role during Mp infection, in part through epithelial-driven host defense mechanisms.

High cytomegalovirus serology and subsequent COPD-related mortality: a longitudinal study.

BACKGROUND: Positive serology for cytomegalovirus (CMV) has been associated with all-cause mortality risk but its role in COPD mortality is unknown. The objective of the present study was to assess the relationship between CMV serology and COPD mortality. METHODS: We analysed data from 806 participants in the Tucson Epidemiological Study of Airway Obstructive Disease who, at enrolment, were aged 28-70 years and had completed lung function tests. We tested CMV serology in sera from enrolment and defined "high CMV serology" as being in the highest tertile. Vital status, date and cause of death were assessed through death certificates and/or linkage with the National Death Index up to January 2017. The association of CMV serology with all-cause and cause-specific mortality risk was tested in Cox models adjusted for age, sex, level of education, body mass index, smoking status and pack-years. RESULTS: High CMV serology was marginally associated with all-cause mortality (p=0.071) but the effect was inversely dependent on age, with the association being much stronger among participants <55 years than among participants ≥55 years at enrolment (p-value for CMV-by-age interaction <0.001). Compared with low CMV serology, high CMV serology was associated with mortality from COPD among all subjects (adjusted hazard ratio (HR) 2.38, 95% CI 1.11-5.08; p=0.025) and particularly in subjects <55 years old at enrolment (HR 5.40, 95% CI 1.73-16.9; p=0.004). Consistent with these results, high CMV serology also predicted mortality risk among subjects who already had airflow limitation at enrolment (HR 2.10, 95% CI 1.20-3.68; p=0.009). CONCLUSIONS: We report a strong relationship between CMV serology and the risk of dying from COPD, and thus identify a novel risk factor for COPD mortality.

COPD: To Be or Not to Be, That is the Question.

As our knowledge on the natural history of chronic obstructive pulmonary disease (COPD) progresses, a conceptual model simply based on an accelerated decline of lung function in adult life in response to smoking has become inadequate to capture the complexity of this disease, and increasing attention is being given to possible contributions from events or alterations of developmental processes that take place earlier in life. In addition, a remarkable heterogeneity has emerged among the pathobiological mechanisms that are involved in different phenotypes of COPD, suggesting that an effective disease management will require individualized treatment approaches largely based on the underlying biological mechanisms (endotypes). In this review, we will discuss the many faces of COPD from an epidemiological, pathobiological, and clinical standpoint and argue that airflow limitation encompasses a number of manifestations that are too diverse to be still clustered under the same diagnostic label.

CC16 Levels into Adult Life Are Associated with Nitrogen Dioxide Exposure at Birth.

Rationale: Lung function and growth are adversely associated with nitrogen dioxide (NO2) exposure. Lower levels of circulating club cell secretory protein (CC16) in childhood are also associated with subsequent decreased lung function. NO2 exposure may induce epithelial damage in lungs and alter club cell proliferation and morphology.Objectives: To determine if increased ambient NO2 levels at participants' home addresses in early life were associated with decreased levels of CC16 from age 6 to 32 years.Methods: Participants were enrolled at birth in the Tucson Children's Respiratory Study and had circulating CC16 measured at least once between age 6 and 32. Linear mixed models were used to determine the association between estimated ambient NO2 exposure at participants' home address at birth or age 6 with CC16 levels from age 6 to 32.Measurements and Main Results: NO2 exposures at birth or age 6 were available for 777 children with one or more CC16 measurement. We found a negative association between NO2 exposure and CC16 levels, with a 4.7% (95% confidence interval, -8.6 to -0.7) decrease in CC16 levels from age 6 to 32 per interquartile range increase in NO2 exposure (6.0 ppb) at the participants' birth address. We observed modification by race (p interaction = 0.04), with stronger associations among participants with at least one black parent (-29.6% [95% confidence interval, -42.9% to -13.2%] per interquartile range). NO2 at participant's age 6 address was not significantly associated with CC16 levels (-1.9%; 95% confidence interval, -6.3 to 2.6).Conclusions: Higher exposure to NO2 at birth is associated with persistently low levels of CC16 from 6 to 32 years.

Early life determinants of lung function change from childhood to adolescence.

RATIONALE: Little is known about how perinatal and childhood factors influence lung function change between childhood and adolescence. OBJECTIVES: To investigate possible early life predictors of change in FEV1 between age 8 and 16 years. In addition, to investigate possible predictors of having persistently low lung function (FEV1 <25th percentiles both at age 8 and 16) up to adolescence. METHODS: The BAMSE birth cohort study collected data throughout childhood on environmental factors, individual characteristics, and spirometric measures at 8 and 16 years (n = 1425). Associations between early life predictors (n = 31) and FEV1 increase between 8 and 16 years were assessed with linear regression. Predictors of having persistently low lung function were examined. RESULTS: Few factors were consistently associated with altered lung function growth, although low birth weight, asthma heredity (paternal), secondhand smoke in infancy, and season of birth had a significant impact (p-value ≤0.01). The majority of subjects stayed however within the same category of lung function between ages 8 and 16 years (in total 821/1425 = 58%). Predictors associated with having persistently low lung function were gestational age, secondhand smoke (at 2 and 8 years of age), and factors related to lower respiratory tract infections in infancy. CONCLUSIONS: In summary, rather few exposures in childhood were identified to have a significant impact on lung function growth between childhood and adolescence. Our data support previous study findings indicating that lung function development is influenced by factors before birth and in infancy, including second hand tobacco smoke.

Protective effect of breastfeeding on recurrent cough in adulthood.

RATIONALE: Breastfeeding protects from respiratory infections in early life but its relationship to recurrent cough and other respiratory outcomes in adult life is not well established. METHODS: Infant feeding practices were assessed prospectively in the Tucson Children's Respiratory Study, a non-selected birth cohort and categorised into formula from birth or introduced <1 month, formula introduced ≥1 to <4 months and exclusive breastfeeding for ≥4 months. Infant feeding was assessed as an ordinal variable representing an increasing dose of breastmilk across the three categories. Recurrent cough was defined at 22, 26 and 32 years as ≥2 episodes of cough without a cold lasting 1 week during the past year. Covariates included participant sex, race/ethnicity and smoking as well as parental smoking, education, age and asthma. Covariates were evaluated as potential confounders for the relation between infant feeding and adult outcomes. RESULTS: Of the 786 participants, 19% breastfed <1 month, 50% breastfed ≥1 to <4 months and 31% breastfed ≥4 months. The prevalence of recurrent cough at 22, 26 and 32 years was 17%, 15% and 16%, respectively. Each ordinal increase in breastfeeding duration was associated with a decreased risk of recurrent cough in adult life: adjusted OR=0.71, (95% CI: 0.56 to 0.89), p=0.004. Additional adjustment for concurrent adult asthma, wheeze, smoking and lung volume did not change these results. CONCLUSION: Longer duration of breastfeeding reduces the risk of recurrent cough in adult life, regardless of smoking and other respiratory symptoms, suggesting long-term protective effects on respiratory health.

Persistent light to moderate alcohol intake and lung function: A longitudinal study.

Alcohol intake has been inconsistently associated with lung function levels in cross-sectional studies. The goal of our study was to determine whether longitudinally assessed light-to-moderate alcohol intake is associated with levels and decline of lung function. We examined data from 1333 adult participants in the population-based Tucson Epidemiological Study of Airway Obstructive Disease. Alcohol intake was assessed with four surveys between 1972 and 1992. Subjects who completed at least two surveys were classified into longitudinal drinking categories ("never", "inconsistent", or "persistent drinker"). Spirometric lung function was measured in up to 11 surveys between 1972 and 1992. Random coefficient models were used to test for differences in lung function by drinking categories. After adjustment for sex, age, height, education, BMI categories, smoking status, and pack-years, as compared to never-drinkers, persistent drinkers had higher FVC (coefficient: 157 mL, p < 0.001), but lower FEV1/FVC ratio (-2.3%, p < 0.001). Differences were due to a slower decline of FVC among persistent than among never-drinkers (p = 0.003), and these trends were present independent of smoking status. Inconsistent drinking showed similar, but weaker associations. After adjustment for potential confounders, light-to-moderate alcohol consumption was associated with a significantly decreased rate of FVC decline over adult life.

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.

Health-related quality of life and risk factors associated with spirometric restriction.

The restrictive spirometric pattern is associated with a substantial morbidity and mortality burden. We sought to determine to what extent spirometric restriction is associated with impaired quality of life.We used data from two large population-based European cohorts: 6698 European Community Respiratory Health Survey (ECRHS) and 6069 Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA) adult participants. The restrictive pattern was defined as forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ≥lower limit of normal (LLN) and FVC