Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement

Background: Spirometry is the most common pulmonary function test. It is widely used in the assessment of lung function to provide objective information used in the diagnosis of lung diseases and monitoring lung health. In 2005, the American Thoracic Society and the European Respiratory Society jointly adopted technical standards for conducting spirometry. Improvements in instrumentation and computational capabilities, together with new research studies and enhanced quality assurance approaches, have led to the need to update the 2005 technical standards for spirometry to take full advantage of current technical capabilities.Methods: This spirometry technical standards document was developed by an international joint task force, appointed by the American Thoracic Society and the European Respiratory Society, with expertise in conducting and analyzing pulmonary function tests, laboratory quality assurance, and developing international standards. A comprehensive review of published evidence was performed. A patient survey was developed to capture patients' experiences.Results: Revisions to the 2005 technical standards for spirometry were made, including the addition of factors that were not previously considered. Evidence to support the revisions was cited when applicable. The experience and expertise of task force members were used to develop recommended best practices.Conclusions: Standards and consensus recommendations are presented for manufacturers, clinicians, operators, and researchers with the aims of increasing the accuracy, precision, and quality of spirometric measurements and improving the patient experience. A comprehensive guide to aid in the implementation of these standards was developed as an online supplement.

ERS/ATS technical standard on interpretive strategies for routine lung function tests

BACKGROUND

Appropriate interpretation of pulmonary function tests (PFTs) involves the classification of observed values as within/outside the normal range based on a reference population of healthy individuals, integrating knowledge of physiological determinants of test results into functional classifications and integrating patterns with other clinical data to estimate prognosis. In 2005, the American Thoracic Society (ATS) and European Respiratory Society (ERS) jointly adopted technical standards for the interpretation of PFTs. We aimed to update the 2005 recommendations and incorporate evidence from recent literature to establish new standards for PFT interpretation.

METHODS

This technical standards document was developed by an international joint Task Force, appointed by the ERS/ATS with multidisciplinary expertise in conducting and interpreting PFTs and developing international standards. A comprehensive literature review was conducted and published evidence was reviewed.

RESULTS

Recommendations for the choice of reference equations and limits of normal of the healthy population to identify individuals with unusually low or high results are discussed. Interpretation strategies for bronchodilator responsiveness testing, limits of natural changes over time and severity are also updated. Interpretation of measurements made by spirometry, lung volumes and gas transfer are described as they relate to underlying pathophysiology with updated classification protocols of common impairments.

CONCLUSIONS

Interpretation of PFTs must be complemented with clinical expertise and consideration of the inherent biological variability of the test and the uncertainty of the test result to ensure appropriate interpretation of an individual's lung function measurements.

Recommendations for a Standardized Pulmonary Function Report. An Official American Thoracic Society Technical Statement

BACKGROUND

The American Thoracic Society committee on Proficiency Standards for Pulmonary Function Laboratories has recognized the need for a standardized reporting format for pulmonary function tests. Although prior documents have offered guidance on the reporting of test data, there is considerable variability in how these results are presented to end users, leading to potential confusion and miscommunication.

METHODS

A project task force, consisting of the committee as a whole, was approved to develop a new Technical Standard on reporting pulmonary function test results. Three working groups addressed the presentation format, the reference data supporting interpretation of results, and a system for grading quality of test efforts. Each group reviewed relevant literature and wrote drafts that were merged into the final document.

RESULTS

This document presents a reporting format in test-specific units for spirometry, lung volumes, and diffusing capacity that can be assembled into a report appropriate for a laboratory's practice. Recommended reference sources are updated with data for spirometry and diffusing capacity published since prior documents. A grading system is presented to encourage uniformity in the important function of test quality assessment.

CONCLUSIONS

The committee believes that wide adoption of these formats and their underlying principles by equipment manufacturers and pulmonary function laboratories can improve the interpretation, communication, and understanding of test results.

Inflammatory basis of exercise-induced bronchoconstriction

RATIONALE

Exercise-induced bronchoconstriction (EIB) is a highly prevalent condition with unclear pathogenesis. Two competing theories of the pathogenesis of EIB differ regarding the inflammatory basis of this condition.

OBJECTIVES

Our goals were to establish whether epithelial cell and mast cell activation with release of inflammatory mediators occurs during EIB and how histamine and cysteinyl leukotriene antagonists alter the airway events occurring during EIB.

METHODS

Induced sputum was used to measure mast cell mediators and eicosanoids at baseline and 30 minutes after exercise challenge in 25 individuals with asthma with EIB. In a randomized, double-blind crossover study, the cysteinyl leukotriene antagonist montelukast and antihistamine loratadine or two matched placebos were administered for two doses before exercise challenge.

MAIN RESULTS

The percentage of columnar epithelial cells in induced sputum at baseline was associated with the severity of EIB. After exercise challenge, histamine, tryptase, and cysteinyl leukotrienes significantly increased and prostaglandin E(2) and thromboxane B(2) significantly decreased in the airways, and there was an increase in columnar epithelial cells in the airways. The concentration of columnar epithelial cells was associated with the levels of histamine and cysteinyl leukotrienes in the airways. Treatment with montelukast and loratadine inhibited the release of cysteinyl leukotrienes and histamine into the airways, but did not inhibit the release of columnar epithelial cells into the airways.

CONCLUSIONS

These data indicate that epithelial cells, mast cell mediators, and eicosanoids are released into the airways during EIB, supporting an inflammatory basis for EIB.

Airway epithelial regulation of pulmonary immune homeostasis and inflammation

Recent genetic, structural and functional studies have identified the airway and lung epithelium as a key orchestrator of the immune response. Further, there is now strong evidence that epithelium dysfunction is involved in the development of inflammatory disorders of the lung. Here we review the characteristic immune responses that are orchestrated by the epithelium in response to diverse triggers such as pollutants, cigarette smoke, bacterial peptides, and viruses. We focus in part on the role of epithelium-derived interleukin (IL)-25, IL-33 and thymic stromal lymphopoietin (TSLP), as well as CC family chemokines as critical regulators of the immune response. We cite examples of the function of the epithelium in host defense and the role of epithelium dysfunction in the development of inflammatory diseases.

ERS technical standard on bronchial challenge testing: general considerations and performance of methacholine challenge tests

This international task force report updates general considerations for bronchial challenge testing and the performance of the methacholine challenge test. There are notable changes from prior recommendations in order to accommodate newer delivery devices. Rather than basing the test result upon a methacholine concentration (provocative concentration (PC20) causing a 20% fall in forced expiratory volume in 1 s (FEV1)), the new recommendations base the result upon the delivered dose of methacholine causing a 20% fall in FEV1 (provocative dose (PD20)). This end-point allows comparable results from different devices or protocols, thus any suitable nebuliser or dosimeter may be used, so long as the delivery characteristics are known. Inhalation may be by tidal breathing using a breath-actuated or continuous nebuliser for 1 min (or more), or by a dosimeter with a suitable breath count. Tests requiring maximal inhalations to total lung capacity are not recommended because the bronchoprotective effect of a deep breath reduces the sensitivity of the test.

Improved sensitivity mass spectrometric detection of eicosanoids by charge reversal derivatization

Combined liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) is a powerful method for the analysis of oxygenated metabolites of polyunsaturated fatty acids including eicosanoids. Here we describe the synthesis of a new derivatization reagent N-(4-aminomethylphenyl)pyridinium (AMPP) that can be coupled to eicosanoids via an amide linkage in quantitative yield. Conversion of the carboxylic acid of eicosanoids to a cationic AMPP amide improves sensitivity of detection by 10- to 20-fold compared to negative mode electrospray ionization detection of underivatized analytes. This charge reversal derivatization allows detection of cations rather than anions in the electrospray ionization mass spectrometer, which enhances sensitivity. Another factor is that AMPP amides undergo considerable collision-induced dissociation in the analyte portion rather than exclusively in the cationic tag portion, which allows isobaric derivatives to be distinguished by tandem mass spectrometry, and this further enhances sensitivity and specificity. This simple derivatization method allows prostaglandins, thromboxane B(2), leukotriene B(4), hydroxyeicosatetraenoic acid isomers, and arachidonic acid to be quantified in complex biological samples with limits of quantification in the 200-900 fg range. One can anticipate that the AMPP derivatization method can be extended to other carboxylic acid analytes for enhanced sensitivity detection.

Decreased fibronectin production significantly contributes to dysregulated repair of asthmatic epithelium

RATIONALE

Damage to airway epithelium is followed by deposition of extracellular matrix (ECM) and migration of adjacent epithelial cells. We have shown that epithelial cells from children with asthma fail to heal a wound in vitro.

OBJECTIVES

To determine whether dysregulated ECM production by the epithelium plays a role in aberrant repair in asthma.

METHODS

Airway epithelial cells (AEC) from children with asthma (n = 36), healthy atopic control subjects (n = 23), and healthy nonatopic control subjects (n = 53) were investigated by microarray, gene expression and silencing, transcript regulation analysis, and ability to close mechanical wounds.

MEASUREMENTS AND MAIN RESULTS

Time to repair a mechanical wound in vitro by AEC from healthy and atopic children was not significantly different and both were faster than AEC from children with asthma. Microarray analysis revealed differential expression of multiple gene sets associated with repair and remodeling in asthmatic AEC. Fibronectin (FN) was the only ECM component whose expression was significantly lower in asthmatic AEC. Expression differences were verified by quantitative polymerase chain reaction and ELISA, and reduced FN expression persisted in asthmatic cells over passage. Silencing of FN expression in nonasthmatic AEC inhibited wound repair, whereas addition of FN to asthmatic AEC restored reparative capacity. Asthmatic AEC failed to synthesize FN in response to wounding or cytokine/growth factor stimulation. Exposure to 5', 2'deoxyazacytidine had no effect on FN expression and subsequent analysis of the FN promoter did not show evidence of DNA methylation.

CONCLUSIONS

These data show that the reduced capacity of asthmatic epithelial cells to secrete FN is an important contributor to the dysregulated AEC repair observed in these cells.

The timed walk test as a measure of severity and survival in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a relentlessly progressive disease with a median survival of approximately 3 yrs. Measurements of airflow and lung volumes at rest are generally used to monitor the clinical course in this disorder. This study was designed to determine if a modified version of the 6-min walk test, called the timed walk test, accurately characterises disease severity and survival in IPF. The study population consisted of 28 patients with well-characterised progressive IPF. The timed walk test and concurrent measures of disease severity were assessed at baseline. Participants were prospectively followed for > or =4 yrs to determine the relationship between parameters of the timed walk test and survival. There were strong correlations between the end-exercise saturation and walk-velocity parameters of the timed walk test and diffusing capacity, and arterial oxygen tension at rest. In univariate Cox proportional-hazards models, end-exercise saturation, change in saturation with exercise, walk distance and walk velocity were associated with survival. In unadjusted logistic regression models, odds of death at 2 yrs were associated with the same parameters. In conclusion, the timed walk test relates to disease severity and long-term outcome in progressive idiopathic pulmonary fibrosis.

Exercise-induced bronchoconstriction update-2016

The first practice parameter on exercise-induced bronchoconstriction (EIB) was published in 2010. This updated practice parameter was prepared 5 years later. In the ensuing years, there has been increased understanding of the pathogenesis of EIB and improved diagnosis of this disorder by using objective testing. At the time of this publication, observations included the following: dry powder mannitol for inhalation as a bronchial provocation test is FDA approved however not currently available in the United States; if baseline pulmonary function test results are normal to near normal (before and after bronchodilator) in a person with suspected EIB, then further testing should be performed by using standardized exercise challenge or eucapnic voluntary hyperpnea (EVH); and the efficacy of nonpharmaceutical interventions (omega-3 fatty acids) has been challenged. The workgroup preparing this practice parameter updated contemporary practice guidelines based on a current systematic literature review. The group obtained supplementary literature and consensus expert opinions when the published literature was insufficient. A search of the medical literature on PubMed was conducted, and search terms included pathogenesis, diagnosis, differential diagnosis, and therapy (both pharmaceutical and nonpharmaceutical) of exercise-induced bronchoconstriction or exercise-induced asthma (which is no longer a preferred term); asthma; and exercise and asthma. References assessed as relevant to the topic were evaluated to search for additional relevant references. Published clinical studies were appraised by category of evidence and used to document the strength of the recommendation. The parameter was then evaluated by Joint Task Force reviewers and then by reviewers assigned by the parent organizations, as well as the general membership. Based on this process, the parameter can be characterized as an evidence- and consensus-based document.

Effectiveness of screening examinations to detect unrecognized exercise-induced bronchoconstriction

OBJECTIVE

To determine if a physician-administered physical examination and screening questionnaire accurately detects exercise-induced bronchoconstriction (EIB) in adolescent athletes.

STUDY DESIGN

Cross-sectional study of 256 adolescents participating in organized sports from 3 suburban high schools. The number of persons screened positive for EIB by physical examination and questionnaire was compared with the number of persons with EIB diagnosed by a "gold standard" test that consisted of a 7-minute exercise challenge followed by serial spirometry.

RESULTS

We diagnosed EIB in 9.4% of adolescent athletes. The screening history identified persons with symptoms or a previous diagnosis suggestive of EIB in 39.5% of the participants, but only 12.9% of these persons actually had EIB. Among adolescents with a negative review of symptoms of asthma or EIB, 7.8% had EIB. Among adolescents with no previous diagnosis of asthma, allergic rhinitis, or EIB, 7.2% had EIB diagnosed by exercise challenge. Persons who screened negative on all questions about symptoms or history of asthma, EIB, and allergic rhinitis accounted for 45.8% of the adolescents with EIB.

CONCLUSIONS

EIB occurs frequently in adolescent athletes, and screening by physical examination and medical history does not accurately detect it.

Genetic pleiotropy between asthma and obesity in a community-based sample of twins

BACKGROUND

Asthma and obesity are common conditions that are strongly associated. This association might be due to shared genetic or environmental causes.

OBJECTIVE

We sought to determine whether a shared genetic cause is responsible for the association between asthma and obesity and to estimate the magnitude of shared genetic cause.

METHODS

The analyses were performed with 1001 monozygotic and 383 dizygotic same-sex twin pairs within the University of Washington Twin Registry. The presence of asthma was determined by self-report of a physician diagnosis of asthma, and body mass index (BMI) was calculated by using self-reported height and weight. Obesity was defined as a BMI of 30 or greater. The association between asthma and BMI was assessed by means of mixed-effects ordinal regression. Twin correlations examined the association of asthma and obesity. Univariate and bivariate structural equation models estimated the components of variance attributable to genetic and environmental effects.

RESULTS

A strong association between asthma and BMI was identified in the sample population (P < .001). Substantial heritability was detected for asthma (53%) and obesity (77%), which is indicative of additive genetic influences on each disorder. The best-fitting model of shared components of variance indicated that 8% of the genetic component of obesity is shared with asthma.

CONCLUSION

The covariation between obesity and asthma is predominantly caused by shared genetic risk factors for both conditions.

Airway immunopathology of asthma with exercise-induced bronchoconstriction

BACKGROUND

Exercise-induced bronchoconstriction (EIB) is a common cause of symptoms in a subgroup of asthmatic subjects. The pathobiology that makes this group of asthmatic subjects susceptible to bronchoconstriction after a brief period of exercise remains poorly understood.

OBJECTIVE

We sought to determine whether there are differences in lower airway inflammation and production of cytokines and eicosanoids between asthmatic subjects with and without EIB.

METHODS

Two distinct groups of asthmatic subjects based on a priori definitions were identified, one with moderate-to-severe EIB and the other without significant bronchoconstriction after exercise challenge. Both groups met the definition of asthma on the basis of bronchodilator response, bronchial hyperresponsiveness, or both. A comparative immunopathology study was conducted by using induced sputum to identify differences in lower airway inflammation and production of cytokines and eicosanoids.

RESULTS

The groups had similar baseline lung function and bronchodilator response and did not have any asthma exacerbations within the prior year. The concentration of columnar epithelial cells was markedly higher in the group with EIB (1.4 x 10(5) vs 2.9 x 10(4) cells/mL, P=.01). The concentration of eosinophils was higher in the group with EIB (3.6 x 10(4) vs 4.9 x 10(3) cells/mL P=.04). Cysteinyl leukotrienes (CysLTs; 727.7 vs 151.9 pg/mL, P=.01) and the ratio of CysLTs to prostaglandin E(2) (1.85 vs 1.04, P=.002) in the airways were higher in the group with EIB.

CONCLUSION

Injury to the airway epithelium, overexpression of CysLTs, relative under production of prostaglandin E(2), and greater airway eosinophilia are distinctive immunopathologic features of asthma with EIB.

Ambient air pollution, lung function, and airway responsiveness in asthmatic children

BACKGROUND

Although ambient air pollution has been linked to reduced lung function in healthy children, longitudinal analyses of pollution effects in asthmatic patients are lacking.

OBJECTIVE

We sought to investigate pollution effects in a longitudinal asthma study and effect modification by controller medications.

METHODS

We examined associations of lung function and methacholine responsiveness (PC20) with ozone, carbon monoxide (CO), nitrogen dioxide, and sulfur dioxide concentrations in 1003 asthmatic children participating in a 4-year clinical trial. We further investigated whether budesonide and nedocromil modified pollution effects. Daily pollutant concentrations were linked to ZIP/postal code of residence. Linear mixed models tested associations of within-subject pollutant concentrations with FEV1 and forced vital capacity (FVC) percent predicted, FEV1/FVC ratio, and PC20, adjusting for seasonality and confounders.

RESULTS

Same-day and 1-week average CO concentrations were negatively associated with postbronchodilator percent predicted FEV1 (change per interquartile range, -0.33 [95% CI, -0.49 to -0.16] and -0.41 [95% CI, -0.62 to -0.21], respectively) and FVC (-0.19 [95% CI, -0.25 to -0.07] and -0.25 [95% CI, -0.43 to -0.07], respectively). Longer-term 4-month CO averages were negatively associated with prebronchodilator percent predicted FEV1 and FVC (-0.36 [95% CI, -0.62 to -0.10] and -0.21 [95% CI, -0.42 to -0.01], respectively). Four-month averaged CO and ozone concentrations were negatively associated with FEV1/FVC ratio (P < .05). Increased 4-month average nitrogen dioxide concentrations were associated with reduced postbronchodilator FEV1 and FVC percent predicted. Long-term exposures to sulfur dioxide were associated with reduced PC20 (percent change per interquartile range, -6% [95% CI, -11% to -1.5%]). Treatment augmented the negative short-term CO effect on PC20.

CONCLUSIONS

Air pollution adversely influences lung function and PC20 in asthmatic children. Treatment with controller medications might not protect but rather worsens the effects of CO on PC20. This clinical trial design evaluates modification of pollution effects by treatment without confounding by indication.

Secreted phospholipase A2 group X overexpression in asthma and bronchial hyperresponsiveness

RATIONALE

Secreted phospholipase A(2) enzymes (sPLA(2)s) play key regulatory roles in the biosynthesis of eicosanoids, such as the cysteinyl leukotrienes, but the role of these enzymes in the pathogenesis of asthma is not known.

OBJECTIVES

To establish if sPLA(2)s are overexpressed in the airways of patients with asthma, and to determine if these enzymes may play a role in the generation of eicosanoids in exercise-induced bronchoconstriction.

METHODS

Induced sputum samples were obtained from subjects with asthma with exercise-induced bronchoconstriction and nonasthmatic control subjects at baseline, and on a separate day 30 minutes after exercise challenge. The expression of the PLA(2)s in induced sputum cells and supernatant was determined by quantitative polymerase chain reaction, immunocytochemistry, and Western blot.

MEASUREMENTS AND MAIN RESULTS

The sPLA(2)s expressed at the highest levels in airway cells of subjects with asthma were groups X and XIIA. Group X sPLA(2) (sPLA(2)-X) was differentially overexpressed in asthma and localized to airway epithelial cells and bronchial macrophages. The gene expression, immunostaining in airway epithelial cells and bronchial macrophages, and the level of the extracellular sPLA(2)-X protein in the airways increased in response to exercise challenge in the asthma group, whereas the levels were lower and unchanged after challenge in nonasthmatic control subjects.

CONCLUSIONS

Increased expression of sPLA(2)-X may play a key role in the dysregulated eicosanoid synthesis in asthma.

ERS technical standard on bronchial challenge testing: pathophysiology and methodology of indirect airway challenge testing

Recently, this international task force reported the general considerations for bronchial challenge testing and the performance of the methacholine challenge test, a "direct" airway challenge test. Here, the task force provides an updated description of the pathophysiology and the methods to conduct indirect challenge tests. Because indirect challenge tests trigger airway narrowing through the activation of endogenous pathways that are involved in asthma, indirect challenge tests tend to be specific for asthma and reveal much about the biology of asthma, but may be less sensitive than direct tests for the detection of airway hyperresponsiveness. We provide recommendations for the conduct and interpretation of hyperpnoea challenge tests such as dry air exercise challenge and eucapnic voluntary hyperpnoea that provide a single strong stimulus for airway narrowing. This technical standard expands the recommendations to additional indirect tests such as hypertonic saline, mannitol and adenosine challenge that are incremental tests, but still retain characteristics of other indirect challenges. Assessment of airway hyperresponsiveness, with direct and indirect tests, are valuable tools to understand and to monitor airway function and to characterise the underlying asthma phenotype to guide therapy. The tests should be interpreted within the context of the clinical features of asthma.

Aerobic conditioning in mild asthma decreases the hyperpnea of exercise and improves exercise and ventilatory capacity

STUDY OBJECTIVE

To determine the effect of an aerobic conditioning program on fitness, respiratory physiology, and resting lung function in patients with mild asthma.

DESIGN

Prospective cohort study.

SETTING

Outpatient rehabilitation facility.

METHODS

Five patients with mild intermittent asthma and five normal control subjects completed a 10-week aerobic conditioning program. Pulmonary function studies and noninvasive cardiopulmonary exercise tests were performed before and after the conditioning program.

RESULTS

After aerobic conditioning, there were significant gains in maximum oxygen consumption (VO(2)max; 22.73 mL/kg/min vs 25.29 mL/kg/min, p = 0.01, asthma; 22.94 mL/kg/min vs 27.85 mL/kg/min, p = 0.03, control) and anaerobic threshold (0.99 L/min vs 1.09 L/min, p = 0.03, asthma; 0.89 L/min vs 1.13 L/min, p = 0.01, control) in both groups. Although FEV(1) was unchanged, the maximum voluntary ventilation (MVV) improved in the asthma group (96.0 L/min vs 108.2 L/min, p = 0.08, asthma; 134.0 L/min vs 131.2 L/min, p = 0.35, control). During exercise, minute ventilation (VE) for each level of work was decreased in the asthma group after conditioning, while little change occurred in the control group (68. 48 L/min vs 51.70 L/min at initial VO(2)max, p = 0. 02, asthma; 65.82 L/min vs 63.12 L/min at initial VO(2)max, p = 0.60, control). A significant decrease in the ventilatory equivalent (VE/oxygen consumption, 40.8 vs 30.4 at VO(2)max, p = 0.02, asthma; 37.2 vs 35.8 4 at VO(2)max, p = 0.02, control) and the dyspnea index (VE/MVV) at submaximal (0.44 vs 0.38, p = 0.05, asthma; 0.32 vs 0.38, p < 0.01, control) and maximal exercise (0.72 vs 0.63, p = 0.03, asthma; 0.49 vs 0.62, p = 0.02, control) occurred in the asthma group.

CONCLUSIONS

Exercise rehabilitation improves aerobic fitness in both asthmatic and nonasthmatic participants of a 10-week aerobic fitness program. Additional benefits of improved ventilatory capacity and decreased hyperpnea of exercise occurred in patients with mild asthma.

Use of Fractional Exhaled Nitric Oxide to Guide the Treatment of Asthma: An Official American Thoracic Society Clinical Practice Guideline

Background: The fractional exhaled nitric oxide (FE_NO) test is a point-of-care test that is used in the assessment of asthma.

Objective: To provide evidence-based clinical guidance on whether FE_NO testing is indicated to optimize asthma treatment in patients with asthma in whom treatment is being considered.

Methods: An international, multidisciplinary panel of experts was convened to form a consensus document regarding a single question relevant to the use of FE_NO. The question was selected from three potential questions based on the greatest perceived impact on clinical practice and the unmet need for evidence-based answers related to this question. The panel performed systematic reviews of published randomized controlled trials between 2004 and 2019 and followed the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) evidence-to-decision framework to develop recommendations. All panel members evaluated and approved the recommendations.

Main Results: After considering the overall low quality of the evidence, the panel made a conditional recommendation for FE_NO-based care. In patients with asthma in whom treatment is being considered, we suggest that FE_NO is beneficial and should be used in addition to usual care. This judgment is based on a balance of effects that probably favors the intervention; the moderate costs and availability of resources, which probably favors the intervention; and the perceived acceptability and feasibility of the intervention in daily practice.

Conclusions: Clinicians should consider this recommendation to measure FE_NO in patients with asthma in whom treatment is being considered based on current best available evidence.

Airway epithelium-shifted mast cell infiltration regulates asthmatic inflammation via IL-33 signaling

Asthma is a heterogeneous syndrome that has been subdivided into physiologic phenotypes and molecular endotypes. The most specific phenotypic manifestation of asthma is indirect airway hyperresponsiveness (AHR), and a prominent molecular endotype is the presence of type 2 inflammation. The underlying basis for type 2 inflammation and its relationship to AHR are incompletely understood. We assessed the expression of type 2 cytokines in the airways of subjects with and without asthma who were extensively characterized for AHR. Using quantitative morphometry of the airway wall, we identified a shift in mast cells from the submucosa to the airway epithelium specifically associated with both type 2 inflammation and indirect AHR. Using ex vivo modeling of primary airway epithelial cells in organotypic coculture with mast cells, we show that epithelial-derived IL-33 uniquely induced type 2 cytokines in mast cells, which regulated the expression of epithelial IL33 in a feed-forward loop. This feed-forward loop was accentuated in epithelial cells derived from subjects with asthma. These results demonstrate that type 2 inflammation and indirect AHR in asthma are related to a shift in mast cell infiltration to the airway epithelium, and that mast cells cooperate with epithelial cells through IL-33 signaling to regulate type 2 inflammation.

Transglutaminase 2, a novel regulator of eicosanoid production in asthma revealed by genome-wide expression profiling of distinct asthma phenotypes

Background

A frequent manifestation of asthma, exercise-induced bronchoconstriction (EIB), occurs in 30–50% of asthmatics and is characterized by increased release of inflammatory eicosanoids. The objective of this study was to identify genes differentially expressed in EIB and to understand the function of these genes in the biology of asthma.

Methodology/Principal Findings

Genome-wide expression profiling of airway leukocytes and epithelial cells obtained by induced sputum was conducted in two groups of subjects with asthma with and without EIB (n = 7 per group), at baseline and following exercise challenge. Based on the results of the gene expression study, additional comparisons were made with a normal control group (n = 10). Localization studies were conducted on epithelial brushings and biopsies from an additional group of asthmatics with EIB (n = 3). Genes related to epithelial repair and mast cell infiltration including β-tryptase and carboxypeptidase A3 were upregulated by exercise challenge in the asthma group with EIB. A gene novel to asthma pathogenesis, transglutaminase 2 (TGM2), was the most differentially expressed at baseline between the groups. In vivo studies confirmed the increased expression of TGM2 in airway cells and airway lining fluid, and demonstrate that TGM2 is avidly expressed in the asthmatic airway epithelium. In vitro studies using recombinant human enzymes reveal that TGM2 augments the enzymatic activity of secreted phospholipase A₂ (PLA₂) group X (sPLA₂-X), an enzyme recently implicated in asthma pathogenesis.

Conclusions/Significance

This study found that TGM2, a mediator that is novel to asthma pathogenesis, is overexpressed in asthmatic airways and functions to increase sPLA₂-X enzymatic activity. Since PLA₂ serves as the first rate-limiting step leading to eicosanoid formation, these results suggest that TGM2 may be a key initiator of the airway inflammatory cascade in asthma.

Transcription factor p63 regulates key genes and wound repair in human airway epithelial basal cells

The airway epithelium in asthma displays altered repair and incomplete barrier formation. Basal cells are the progenitor cells of the airway epithelium, and can repopulate other cell types after injury. We previously reported increased numbers of basal cells expressing the transcription factor p63 in the airway epithelium of patients with asthma. Here we sought to determine the molecular consequences of p63 expression in basal human airway epithelial cells during wound repair. Because at least six isoforms of p63 exist (N-terminally truncated [ΔN] versus transcriptional activation promoter variants and α, β, or γ 3' splice variants), the expression of all isoforms was investigated in primary human airway epithelial cells (pHAECs). We modulated p63 expression, using small interfering RNA (siRNA) and adenoviral constructs to determine the effects of p63 on 21 candidate target genes by RT-PCR, and on repair using a scratch wound assay. We found that basal pHAECs from asthmatic and nonasthmatic donors predominantly expressed the N-terminally truncated p63α variant (ΔNp63α) isoform, with no disease-specific differences in expression. The knockdown of ΔNp63, using specific siRNA, decreased the expression of 11 out of 21 genes associated with epithelial repair and differentiation, including β-catenin, epidermal growth factor receptor, and Jagged1. The loss of ΔNp63 significantly inhibited wound closure (which was associated with the decreased expression of β-catenin and Jagged1), reduced epithelial proliferation as measured by Ki-67 staining, and increased E-cadherin expression, potentially preventing cytokinesis. In conclusion, ΔNp63α is the major isoform expressed in basal pHAECs, and is essential for epithelial wound repair. The role of ΔNp63α in epithelial barrier integrity requires further study to understand its role in health and disease.

Quality of life in adolescents with mild asthma

The majority of individuals with asthma have mild disease, often in conjunction with allergic rhinitis and exercise-induced bronchoconstriction (EIB). Although health-related quality-of-life (HRQoL) is reduced in moderate to severe asthma and allergic rhinitis, little is known about the effect of mild asthma, mild allergic rhinitis, and EIB on HRQoL outcomes. The objective of this study was to determine the effect of mild asthma, allergic rhinitis, and EIB on HRQoL. A cross-sectional study was conducted of 160 adolescent athletes participating in a screening program to detect EIB. Generic HRQoL was assessed with the teen version of the pediatric quality-of-life inventory (PedsQL). Prior diagnoses of asthma, allergic rhinitis, and EIB, and current symptoms of dyspnea during exercise and asthma, were recorded. Lung function and the presence of EIB were determined by spirometry before and after an exercise challenge test. Adolescent athletes with a prior physician diagnosis of asthma had a lower HRQoL scale summary score (P<0.01) and lower physical functioning, emotional functioning, and school functioning domain scores (P values, 0.01-0.02) in comparison to adolescent athletes with no prior diagnosis of these disorders. Athletes with a prior diagnosis of asthma reported dyspnea during exercise more frequently than did those without asthma (P<0.001). Adolescent athletes with dyspnea during exercise had a lower scale summary score, and lower physical functioning, general well-being, and emotional functioning domain scores (P values, 0.02-0.03). These data show that mild asthma and dyspnea without asthma significantly affect HRQoL. Symptoms of dyspnea during exercise are common in asthma and are associated with lower HRQoL. The clinical significance of these differences in HRQoL is unclear.

Increased density of intraepithelial mast cells in patients with exercise-induced bronchoconstriction regulated through epithelially derived thymic stromal lymphopoietin and IL-33

BACKGROUND

Exercise-induced bronchoconstriction (EIB) is a prototypical feature of indirect airway hyperresponsiveness. Mast cells are implicated in EIB, but the characteristics, regulation, and function of mast cells in patients with EIB are poorly understood.

OBJECTIVES

We sought to examine mast cell infiltration of the airway epithelium in patients with EIB and the regulation of mast cell phenotype and function by epithelially derived cytokines.

METHODS

Endobronchial biopsy specimens, epithelial brushings, and induced sputum were obtained from asthmatic patients with and without EIB and healthy control subjects. Mast cell proteases were quantified by using quantitative PCR, and mast cell density was quantified by using design-based stereology. Airway epithelial responses to wounding and osmotic stress were assessed in primary airway epithelial cells and ex vivo murine lung tissue. Mast cell granule development and function were examined in cord blood-derived mast cells.

RESULTS

Tryptase and carboxypeptidase A3 expression in epithelial brushings and epithelial mast cell density were selectively increased in the asthma group with EIB. An in vitro scratch wound initiated the release of thymic stromal lymphopoietin, which was greater in epithelial cells derived from asthmatic patients. Osmotic stress induced the release of IL-33 from explanted murine lungs, which was increased in allergen-treated mice. Thymic stromal lymphopoietin combined with IL-33 increased tryptase and carboxypeptidase A3 immunostaining in mast cell precursors and selectively increased cysteinyl leukotriene formation by mast cells in a manner that was independent of in vitro sensitization.

CONCLUSIONS

Mast cell infiltration of the epithelium is a critical determinant of indirect airway hyperresponsiveness, and the airway epithelium might serve as an important regulator of the development and function of this mast cell population.

Long-term acquisition of allergen-specific IgE and asthma following allogeneic bone marrow transplantation from allergic donors

Adoptive transfer of allergen-specific immunoglobulin E (IgE) from atopic donors to nonatopic recipients occurs during the first year following bone marrow transplantation (BMT). Mature B- and T-cell clones with allergen-specific memory and hematopoietic progenitor cells are transferred through BMT. The objective of this study was to characterize the long-term rate of allergic sensitization and development of clinical allergic diseases following BMT from atopic donors. A long-term follow-up study was conducted in a cohort of donor and recipient pairs with moderate-to-severe allergic disease in the donor prior to BMT. Assessments of allergen-specific IgE, clinical rhinitis, and asthma were made in the donors prior to BMT and in the recipients with a mean follow-up of 15.5 years after BMT. From an initial cohort of 12 bone marrow transplant recipients who received marrow from allergic donors, 5 long-term survivors were identified. Allergen-specific IgE transferred from donor to recipient following BMT frequently persisted, and a high rate of de novo allergic sensitization was observed between 1 and 14 years after BMT. These events were associated with elevation in total IgE, and development of allergic rhinitis and asthma at long-term follow-up. We conclude that marrow-derived immune cells from allergic donors can transfer the predisposition to allergy and asthma.