Club Cell Secretory Protein in Lung Disease: Emerging Concepts and Potential Therapeutics.

Club cell secretory protein (CCSP), also known as secretoglobin 1A1 (gene name SCGB1A1), is one of the most abundant proteins in the lung, primarily produced by club cells of the distal airway epithelium. At baseline, CCSP is found in large concentrations in lung fluid specimens and can also be detected in the blood and urine. Obstructive lung diseases are generally associated with reduced CCSP levels, thought to be due to decreased CCSP production or club cell depletion. Conversely, several restrictive lung diseases have been found to have increased CCSP levels both in the lung and in the circulation, likely related to club cell dysregulation as well as increasedlung permeability. Recent studies demonstrate multiple mechanisms by which CCSP dampens acute and chronic lung inflammation. Given these anti-inflammatory effects, CCSP represents a novel potential therapeutic modality in lung disease.

Lung-function trajectories: relevance and implementation in clinical practice.

Lung development starts in utero and continues during childhood through to adolescence, reaching its peak in early adulthood. This growth is followed by gradual decline due to physiological lung ageing. Lung-function development can be altered by several host and environmental factors during the life course. As a result, a range of lung-function trajectories exist in the population. Below average trajectories are associated with respiratory, cardiovascular, metabolic, and mental health comorbidities, as well as with premature death. This Review presents progressive research into lung-function trajectories and assists the implementation of this knowledge in clinical practice as an innovative approach to detect poor lung health early, monitor respiratory disease progression, and promote lung health. Specifically, we propose that, similar to paediatric height and weight charts used globally to monitor children's growth, lung-function charts could be used for both children and adults to monitor lung health status across the life course. To achieve this proposal, we introduce our free online Lung Function Tracker tool. Finally, we discuss challenges and opportunities for effective implementation of the trajectory concept at population level and outline an agenda for crucial research needed to support such implementation.

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

Circulating CC16 and Asthma: A Population-based, Multicohort Study from Early Childhood through Adult Life.

Rationale: Club cell secretory protein (CC16) is an antiinflammatory protein highly expressed in the airways. CC16 deficiency has been associated with lung function deficits, but its role in asthma has not been established conclusively. Objectives: To determine 1) the longitudinal association of circulating CC16 with the presence of active asthma from early childhood through adult life and 2) whether CC16 in early childhood predicts the clinical course of childhood asthma into adult life. Methods: We assessed the association of circulating CC16 and asthma in three population-based birth cohorts: the Tucson Children's Respiratory Study (years 6-36; total participants, 814; total observations, 3,042), the Swedish Barn/Children, Allergy, Milieu, Stockholm, Epidemiological survey (years 8-24; total participants, 2,547; total observations, 3,438), and the UK Manchester Asthma and Allergy Study (years 5-18; total participants, 745; total observations, 1,626). Among 233 children who had asthma at the first survey in any of the cohorts, baseline CC16 was also tested for association with persistence of symptoms. Measurements and Main Results: After adjusting for covariates, CC16 deficits were associated with increased risk for the presence of asthma in all cohorts (meta-analyzed adjusted odds ratio per 1-SD CC16 decrease, 1.20; 95% confidence interval [CI], 1.12-1.28; P < 0.0001). The association was particularly strong for asthma with frequent symptoms (meta-analyzed adjusted relative risk ratio, 1.40; 95% CI, 1.24-1.57; P < 0.0001), was confirmed for both atopic and nonatopic asthma, and was independent of lung function impairment. After adjustment for known predictors of persistent asthma, children with asthma in the lowest CC16 tertile had a nearly fourfold increased risk for having frequent symptoms persisting into adult life compared with children with asthma in the other two CC16 tertiles (meta-analyzed adjusted odds ratio, 3.72; 95% CI, 1.78-7.76; P < 0.0001). Conclusions: Circulating CC16 deficits are associated with the presence of asthma with frequent symptoms from childhood through midadult life and predict the persistence of asthma symptoms into adulthood. These findings support a possible protective role of CC16 in asthma and its potential use for risk stratification.

Plasticity of Individual Lung Function States from Childhood to Adulthood.

Rationale: Recent evidence highlights the importance of optimal lung development during childhood for health throughout life. Objectives: To explore the plasticity of individual lung function states during childhood. Methods: Prebronchodilator FEV1 z-scores determined at age 8, 16, and 24 years in the Swedish population-based birth cohort BAMSE (Swedish abbreviation for Child [Barn], Allergy, Milieu, Stockholm, Epidemiological study) (N = 3,069) were used. An unbiased, data-driven dependent mixture model was applied to explore lung function states and individual state chains. Lung function catch-up was defined as participants moving from low or very low states to normal or high or very high states, and growth failure as moving from normal or high or very high states to low or very low states. At 24 years, we compared respiratory symptoms, small airway function (multiple-breath washout), and circulating inflammatory protein levels, by using proteomics, across states. Models were replicated in the independent Dutch population-based PIAMA (Prevention and Incidence of Asthma and Mite Allergy) cohort. Measurements and Main Results: Five lung function states were identified in BAMSE. Lung function catch-up and growth failure were observed in 74 (14.5%) BAMSE participants with low or very low states and 36 (2.4%) participants with normal or high or very high states, respectively. The occurrence of catch-up and growth failure was replicated in PIAMA. Early-life risk factors were cumulatively associated with the very low state, as well as with catch-up (inverse association) and growth failure. The very low state as well as growth failure were associated with respiratory symptoms, airflow limitation, and small airway dysfunction at adulthood. Proteomics identified IL-6 and CXCL10 (C-X-C motif chemokine 10) as potential biomarkers of impaired lung function development. Conclusions: Individual lung function states during childhood are plastic, including catch-up and growth failure.

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.

Creatine Kinase Is Decreased in Childhood Asthma.

Rationale: The identification of novel molecules associated with asthma may provide insights into the mechanisms of disease and their potential clinical implications. Objectives: To conduct a screening of circulating proteins in childhood asthma and to study proteins that emerged from human studies in a mouse model of asthma. Methods: We included 2,264 children from eight birth cohorts from the Mechanisms of the Development of ALLergy project and the Tucson Children's Respiratory Study. In cross-sectional analyses, we tested 46 circulating proteins for association with asthma in the selection stage and carried significant signals forward to a validation and replication stage. As CK (creatine kinase) was the only protein consistently associated with asthma, we also compared whole blood CK gene expression between subjects with and without asthma (n = 249) and used a house dust mite (HDM)-challenged mouse model to gain insights into CK lung expression and its role in the resolution of asthma phenotypes. Measurements and Main Results: As compared with the lowest CK tertile, children in the highest tertile had significantly lower odds for asthma in selection (adjusted odds ratio, 95% confidence interval: 0.31; 0.15-0.65; P = 0.002), validation (0.63; 0.42-0.95; P = 0.03), and replication (0.40; 0.16-0.97; P = 0.04) stages. Both cytosolic CK forms (CKM and CKB) were underexpressed in blood from asthmatics compared with control subjects (P = 0.01 and 0.006, respectively). In the lungs of HDM-challenged mice, Ckb expression was reduced, and after the HDM challenge, a CKB inhibitor blocked the resolution of airway hyperresponsiveness and reduction of airway mucin. Conclusions: Circulating concentrations and gene expression of CK are inversely associated with childhood asthma. Mouse models support a possible direct involvement of CK in asthma protection via inhibition of airway hyperresponsiveness and reduction of airway mucin.

Long-term effect of asthma on the development of obesity among adults: an international cohort study, ECRHS.

INTRODUCTION: Obesity is a known risk factor for asthma. Although some evidence showed asthma causing obesity in children, the link between asthma and obesity has not been investigated in adults. METHODS: We used data from the European Community Respiratory Health Survey (ECRHS), a cohort study in 11 European countries and Australia in 3 waves between 1990 and 2014, at intervals of approximately 10 years. We considered two study periods: from ECRHS I (t) to ECRHS II (t+1), and from ECRHS II (t) to ECRHS III (t+1). We excluded obese (body mass index≥30 kg/m2) individuals at visit t. The relative risk (RR) of obesity at t+1 associated with asthma at t was estimated by multivariable modified Poisson regression (lag) with repeated measurements. Additionally, we examined the association of atopy and asthma medication on the development of obesity. RESULTS: We included 7576 participants in the period ECRHS I-II (51.5% female, mean (SD) age of 34 (7) years) and 4976 in ECRHS II-III (51.3% female, 42 (8) years). 9% of participants became obese in ECRHS I-II and 15% in ECRHS II-III. The risk of developing obesity was higher among asthmatics than non-asthmatics (RR 1.22, 95% CI 1.07 to 1.38), and particularly higher among non-atopic than atopic (1.47; 1.17 to 1.86 vs 1.04; 0.86 to 1.27), those with longer disease duration (1.32; 1.10 to 1.59 in >20 years vs 1.12; 0.87 to 1.43 in ≤20 years) and those on oral corticosteroids (1.99; 1.26 to 3.15 vs 1.15; 1.03 to 1.28). Physical activity was not a mediator of this association. CONCLUSION: This is the first study showing that adult asthmatics have a higher risk of developing obesity than non-asthmatics, particularly those non-atopic, of longer disease duration or on oral corticosteroids.

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.

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.

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 Binding to α4ß1 Integrin Protects against Mycoplasma pneumoniae Infection.

Rationale CC16 (club cell secretory protein) is a pneumoprotein produced predominantly by pulmonary club cells. Circulating CC16 is associated with protection from the inception and progression of the two most common obstructive lung diseases (asthma and chronic obstructive pulmonary disease). Objectives Although exact mechanisms remain elusive, studies consistently suggest a causal role of CC16 in mediating antiinflammatory and antioxidant functions in the lung. We sought to determine any novel receptor systems that could participate in CC16's role in obstructive lung diseases. Methods Protein alignment of CC16 across species led to the discovery of a highly conserved sequence of amino acids, leucine-valine-aspartic acid (LVD), a known integrin-binding motif. Recombinant CC16 was generated with and without the putative integrin-binding site. A Mycoplasma pneumoniae mouse model and a fluorescent cellular adhesion assay were used to determine the impact of the LVD site regarding CC16 function during live infection and on cellular adhesion during inflammatory conditions. Measurements and Main Results CC16 bound to integrin α4ß1), also known as the adhesion molecule VLA-4 (very late antigen 4), dependent on the presence of the LVD integrin-binding motif. During infection, recombinant CC16 rescued lung function parameters both when administered to the lung and intravenously but only when the LVD integrin-binding site was intact; likewise, neutrophil recruitment during infection and leukocyte adhesion were both impacted by the loss of the LVD site. Conclusions We discovered a novel receptor for CC16, VLA-4, which has important mechanistic implications for the role of CC16 in circulation as well as in the lung compartment.

Early-life risk factors for reversible and irreversible airflow limitation in young adults: findings from the BAMSE birth cohort.

We aimed to determine prevalence and early-life risk factors for reversible and irreversible airflow limitation in young adults from the general population. Among young adults in their 20s, the prevalence was 5.3% for reversible airflow limitation and 2.0% for irreversible airflow limitation. While parental asthma was the only risk factor for development of reversible airflow limitation, the risk factors for development of irreversible airflow limitation were current asthma, childhood respiratory tract infections and asthma, and exposure to air pollution.

Dietary intake of vitamin A, lung function and incident asthma in childhood.

BACKGROUND: Longitudinal epidemiological data are scarce on the relationship between dietary intake of vitamin A and respiratory outcomes in childhood. We investigated whether a higher intake of preformed vitamin A or pro-vitamin ß-carotene in mid-childhood is associated with higher lung function and with asthma risk in adolescence. METHODS: In the Avon Longitudinal Study of Parents and Children, dietary intakes of preformed vitamin A and ß-carotene equivalents were estimated by food frequency questionnaire at 7 years of age. Post-bronchodilator forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and forced expiratory flow at 25-75% of FVC (FEF25-75%) were measured at 15.5 years and transformed to z-scores. Incident asthma was defined by new cases of doctor-diagnosed asthma at age 11 or 14 years. RESULTS: In multivariable adjusted models, a higher intake of preformed vitamin A was associated with higher lung function and a lower risk of incident asthma: comparing top versus bottom quartiles of intake, regression coefficients for FEV1 and FEF25-75% were 0.21 (95% CI 0.05-0.38; ptrend=0.008) and 0.18 (95% CI 0.03-0.32; ptrend=0.02), respectively; odds ratios for FEV1/FVC below the lower limit of normal and incident asthma were 0.49 (95% CI 0.27-0.90; ptrend=0.04) and 0.68 (95% CI 0.47-0.99; ptrend=0.07), respectively. In contrast, there was no evidence for association with ß-carotene. We also found some evidence for modification of the associations between preformed vitamin A intake and lung function by BCMO1, NCOR2 and SCGB1A1 gene polymorphisms. CONCLUSION: A higher intake of preformed vitamin A, but not ß-carotene, in mid-childhood is associated with higher subsequent lung function and lower risk of fixed airflow limitation and incident asthma.

Fetal Origins of Asthma: A Longitudinal Study from Birth to Age 36 Years.

Rationale: Deficits in infant lung function-including the ratio of the time to reach peak tidal expiratory flow to the total expiratory time (tptef/te) and maximal expiratory flow at FRC (V̇maxFRC)-have been linked to increased risk for childhood asthma.Objectives: To examine the individual and combined effects of tptef/te and V̇maxFRC in infancy on risk for asthma and abnormalities of airway structure into mid-adult life.Methods: One hundred eighty participants in the Tucson Children's Respiratory Study birth cohort had lung function measured by the chest-compression technique in infancy (mean age ± SD: 2.0 ± 1.2 mo). Active asthma was assessed in up to 12 questionnaires between ages 6 and 36 years. Spirometry and chest high-resolution computed tomographic (HRCT) imaging were completed in a subset of participants at age 26. The relations of infant tptef/te and V̇maxFRC to active asthma and airway structural abnormalities into adult life were tested in multivariable mixed models.Measurements and Main Results: After adjustment for covariates, a 1-SD decrease in infant tptef/te and V̇maxFRC was associated with a 70% (P = 0.001) and 55% (P = 0.005) increased risk of active asthma, respectively. These effects were partly independent, and two out of three infants who were in the lowest tertile for both tptef/te and V̇maxFRC developed active asthma by mid-adult life. Infant V̇maxFRC predicted reduced airflow and infant tptef/te reduced HRCT airway caliber at age 26.Conclusions: These findings underscore the long-lasting effects of the fetal origins of asthma, support independent contributions by infant tptef/te and V̇maxFRC to development of asthma, and link deficits at birth in tptef/te with HRCT-assessed structural airway abnormalities in adult life.

Regular Physical Activity Levels and Incidence of Restrictive Spirometry Pattern: A Longitudinal Analysis of 2 Population-Based Cohorts.

We estimated the association between regular physical activity and the incidence of restrictive spirometry pattern. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and physical activity were assessed in 2 population-based European cohorts (European Community Respiratory Health Survey: n = 2,757, aged 39-67 years; and Swiss Study on Air Pollution and Lung and Heart Diseases in Adults: n = 2,610, aged 36-82 years) first in 2000-2002 and again approximately 10 years later (2010-2013). Subjects with restrictive or obstructive spirometry pattern at baseline were excluded. We assessed the association of being active at baseline (defined as being physically active at least 2-3 times/week for ≥1 hour) with restrictive spirometry pattern at follow-up (defined as a postbronchodilation FEV1/FVC ratio of at least the lower limit of normal and FVC of <80% predicted) using modified Poisson regression, adjusting for relevant confounders. After 10 years of follow-up, 3.3% of participants had developed restrictive spirometry pattern. Being physically active was associated with a lower risk of developing this phenotype (relative risk = 0.76, 95% confidence interval: 0.59, 0.98). This association was stronger among those who were overweight and obese than among those of normal weight (P for interaction = 0.06). In 2 large European studies, adults practicing regular physical activity were at lower risk of developing restrictive spirometry pattern over 10 years.

A novel whole blood gene expression signature for asthma, dermatitis, and rhinitis multimorbidity in children and adolescents.

BACKGROUND: Allergic diseases often occur in combination (multimorbidity). Human blood transcriptome studies have not addressed multimorbidity. Large-scale gene expression data were combined to retrieve biomarkers and signaling pathways to disentangle allergic multimorbidity phenotypes. METHODS: Integrated transcriptomic analysis was conducted in 1233 participants with a discovery phase using gene expression data (Human Transcriptome Array 2.0) from whole blood of 786 children from three European birth cohorts (MeDALL), and a replication phase using RNA Sequencing data from an independent cohort (EVA-PR, n = 447). Allergic diseases (asthma, atopic dermatitis, rhinitis) were considered as single disease or multimorbidity (at least two diseases), and compared with no disease. RESULTS: Fifty genes were differentially expressed in allergic diseases. Thirty-two were not previously described in allergy. Eight genes were consistently overexpressed in all types of multimorbidity for asthma, dermatitis, and rhinitis (CLC, EMR4P, IL5RA, FRRS1, HRH4, SLC29A1, SIGLEC8, IL1RL1). All genes were replicated the in EVA-PR cohort. RT-qPCR validated the overexpression of selected genes. In MeDALL, 27 genes were differentially expressed in rhinitis alone, but none was significant for asthma or dermatitis alone. The multimorbidity signature was enriched in eosinophil-associated immune response and signal transduction. Protein-protein interaction network analysis identified IL5/JAK/STAT and IL33/ST2/IRAK/TRAF as key signaling pathways in multimorbid diseases. Synergistic effect of multimorbidity on gene expression levels was found. CONCLUSION: A signature of eight genes identifies multimorbidity for asthma, rhinitis, and dermatitis. Our results have clinical and mechanistic implications, and suggest that multimorbidity should be considered differently than allergic diseases occurring alone.

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.

Club Cell Secretory Protein Deficiency Leads to Altered Lung Function.

RATIONALE: CC16 (club cell secretory protein-16), a member of the secretoglobin family, is one of the most abundant proteins in normal airway secretions and has been described as a serum biomarker for obstructive lung diseases. OBJECTIVES: To determine whether low CC16 is a marker for airway pathology or is implicated in the pathophysiology of progressive airway damage in these conditions. METHODS: Using human data from the birth cohort of the Tucson Children's Respiratory Study, we examined the relation of circulating CC16 levels with pulmonary function and responses to bronchial methacholine challenge from childhood up to age 32 years. In wild-type and CC16-/- mice, we set out to comprehensively examine pulmonary physiology, inflammation, and remodeling in the naive airway. MEASUREMENTS AND MAIN RESULTS: We observed that Tucson Children's Respiratory Study participants in the lowest tertile of serum CC16 had significant deficits in their lung function and enhanced airway hyperresponsiveness to methacholine challenge from 11 years throughout young adult life. Similarly, CC16-/- mice had significant deficits in lung function and enhanced airway hyperresponsiveness to methacholine as compared with wild-type mice, which were independent of inflammation and mucin production. As compared with wild-type mice, CC16-/- mice had significantly elevated gene expression of procollagen type I, procollagen type III, and α-smooth muscle actin, areas of pronounced collagen deposition and significantly enhanced smooth muscle thickness. CONCLUSIONS: Our findings support clinical observations by providing evidence that lack of CC16 in the lung results in dramatically altered pulmonary function and structural alterations consistent with enhanced remodeling.