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Background: Lung quantitative computed tomography (qCT) severe asthma clusters have been reported, but their replication and underlying disease mechanisms are unknown. We identified and replicated qCT clusters of severe asthma in two independent asthma cohorts and determined their association with molecular pathways, using radiomultiomics, integrating qCT, multiomics and machine learning/artificial intelligence., Methods: We used consensus clustering on qCT measurements of airway and lung CT scans, performed in 105 severe asthmatic adults from the U-BIOPRED cohort. The same qCT measurements were used to replicate qCT clusters in a subsample of the ATLANTIS asthma cohort (n=97). We performed integrated enrichment analysis using blood, sputum, bronchial biopsies, bronchial brushings and nasal brushings transcriptomics and blood and sputum proteomics to characterise radiomultiomic-associated clusters (RACs)., Results: qCT clusters and clinical features in U-BIOPRED were replicated in the matched ATLANTIS cohort. In the U-BIOPRED cohort, RAC1 (n=30) was predominantly female with elevated body mass index, mild airflow limitation, decreased CT lung volume and increased lung density and upregulation of the complement pathway. RAC2 (n=34) subjects had airway wall thickness and a mild degree of airflow limitation, with upregulation of proliferative pathways including neurotrophic receptor tyrosine kinase 2/tyrosine kinase receptor B, and downregulation of semaphorin pathways. RAC3 (n=41) showed increased lung attenuation area and air trapping, severe airflow limitation, hyperinflation, and upregulation of cytokine signalling and signalling by interleukin pathways, and matrix metallopeptidase 1, 2 and 9., Conclusions: U-BIOPRED severe asthma qCT clusters were replicated in a matched independent asthmatic cohort and associated with specific molecular pathways. Radiomultiomics might represent a novel strategy to identify new molecular pathways in asthma pathobiology., Competing Interests: Conflict of interest: K.F. Chung reports grants from the MRC, EPSRC, GSK, Merck and NIEHS, payment or honoraria for lectures, presentations, manuscript writing or educational events from GSK, Novartis and AstraZeneca, and participation on a data safety monitoring board or advisory board with GSK, AstraZeneca, Novartis, Roche, Merck, Trevi, Rickett-Beckinson, Nocion, Shionogi and Clean Breathing Institute supported by Haleon. C. Auffray reports support for the present study from the Innovative Medicines Initiative. Y. Badi reports support for the present study from the Innovative Medicines Initiative. P. Bakke reports payment or honoraria for lectures, presentations, manuscript writing or educational events from AstraZeneca, GSK and Sanofi. C. Brightling reports support for the present study from the ATLANTIS study (Chiesi grant) and Leicester NIHR BRC, grants from 4D Pharma, Areteia, AstraZeneca, Chiesi, Genentech, GSK, Mologic, Novartis, Regeneron Pharmaceuticals, Roche and Sanofi, and consultancy fees from 4D Pharma, Areteia, AstraZeneca, Chiesi, Genentech, GSK, Mologic, Novartis, Regeneron Pharmaceuticals, Roche and Sanofi. P. Chanez reports grants from ALK, AstraZeneca, Boehringer Ingelheim, Chiesi, GSK, Menarini, Novartis and Sanofi Aventis, consultancy fees from ALK, AstraZeneca, Boehringer Ingelheim, Chiesi, GSK, Menarini, Novartis and Sanofi Aventis, payment or honoraria for lectures, presentations, manuscript writing or educational events from ALK, AstraZeneca, Boehringer Ingelheim, Chiesi, GSK, Menarini, Novartis and Sanofi Aventis, and support for attending meetings from ALK, AstraZeneca, Boehringer Ingelheim, Chiesi, GSK, Menarini, Novartis and Sanofi Aventis. B. De Meulder reports support for the present study from the Innovative Medicines Initiative. R. Djukanovic reports consultancy fees from Synairgen plc, GSK, ZenasBio and Celltrion, leadership role as Chair of the European Respiratory Society's clinical research collaboration on severe asthma (SHARP), and stock (or stock options) with Synairgen plc. L. Fabbri reports consultancy fees from Chiesi Farmaceutici and AstraZeneca, payment or honoraria for lectures, presentations, manuscript writing or educational events from Chiesi Farmaceutici, AstraZeneca, GSK, Alfasigma and Novartis, support for attending meetings from Chiesi Farmaceutici, GSK and Novartis, and participation on a data safety monitoring board or advisory board with Novartis and Chiesi. S.J. Fowler reports grants from the NIHR, and payment or honoraria for lectures, presentations, manuscript writing or educational events from Boehringer Ingelheim. P. Howarth reports employment with GSK. J. Kolmert reports consultancy fees from Gesynta Pharma AB and Lipum AB. M. Kraft reports grants from the NIH, American Lung Association, Synairgen, Janssen, AstraZeneca and Sanofi, consultancy fees from AstraZeneca, Sanofi, Chiesi, GSK, Kinaset and Genentech, payment or honoraria for lectures, presentations, manuscript writing or educational events from Chiesi, support for attending meetings from the European Respiratory Society, one patent issued and tiled filed to development of therapeutics for inflammatory lung disease as CoFounder and Chief Medical Officer, RaeSedo, Inc., participation on a data safety monitoring board or advisory board with ALung, leadership role with the National Heart, Lung and Blood Advisory Council, stock (or stock options) with RaeSedo, Inc. (equity ownership), and the following financial (or non-financial) interests: Section Editor of UpToDate. A.H. Maitland-van der Zee reports grants from Health Holland, GSK, Boehringer Ingelheim and Vertex, consultancy fees from Boehringer Ingelheim and AstraZeneca, payment or honoraria for lectures, presentations, manuscript writing or educational events from GSK, and participation on a data safety monitoring board or advisory board for a study on BPD in neonates. A. Papi reports grants from Chiesi, AstraZeneca, GSK and Sanofi, consultancy fees from Chiesi, AstraZeneca, GSK, Novartis, Sanofi, Iqvia, Avillion, Elpen Pharmaceuticals, Moderna and Roche, payment or honoraria for lectures, presentations, manuscript writing or educational events from Chiesi, AstraZeneca, GSK, Menarini, Zambon, Mundipharma, Sanofi, Edmond Pharma, Iqvia, Avillion, Sanofi and Regeneron, participation on a data safety monitoring board or advisory board with Chiesi, AstraZeneca, GSK, Novartis, Sanofi, Iqvia, Avillion, Elpen Pharmaceuticals and Moderna, receipt of equipment, materials, drugs, medical writing, gifts or other services from Consorzio Futuro in Ricerca. K. Rabe reports payment or honoraria for lectures, presentations, manuscript writing or educational events from AstraZeneca, Boehringer Ingelheim, Chiesi Pharmaceuticals, Novartis, Sanofi/Regeneron, GSK, Berlin Chemie and Roche Pharma, participation on a data safety monitoring board or advisory board with AstraZeneca, Boehringer Ingelheim, Sanofi/Regeneron and CSL Behring, and leadership roles with the German Center for Lung Research (DZL), German Chest Society (DGP) and American Thoracic Society. D.E. Shaw reports consultancy fees from GSK, AstraZeneca and Novartis, payment or honoraria for lectures, presentations, manuscript writing or educational events from GSK and AstraZeneca, and support for attending meetings from GSK. D. Singh reports consultancy fees from Aerogen, AstraZeneca, Boehringer Ingelheim, Chiesi, Cipla, CSL Behring, EpiEndo, Genentech, GSK, Glenmark, Gossamer Bio, Kinaset Therapeutics, Menarini, Novartis, Orion, Pulmatrix, Sanofi, Synairgen, Teva, Theravance, Biopharma and Verona Pharma. M. van Den Berge reports grants from GSK, Roche, Genentech and Novartis. Y. Guo reports support for the present study from the Innovative Medicines Initiative. S. Wagers reports consultancy fees from King's College Hospital NHS Foundation Trust, Academic Medical Research, AMC Medical Research BV, Asthma UK, Athens Medical School, Boehringer Ingelheim International GmbH, CHU de Toulouse, CIRO, DS Biologicals Ltd, École Polytechnique Fédérale De Lausanne, European Respiratory Society, FISEVI, Fluidic Analytics Ltd, Fraunhofer IGB, Fraunhofer ITEM, GSK Research & Development Ltd, Holland & Knight, Karolinska Institutet Fakturor, KU Leuven, Longfonds, National Heart and Lung Institute, Novartis Pharma AG, Owlstone Medical Limited, PExA AB, UCB Biopharma SPRL, Umeå University, University Hospital Southampton NHS Foundation Trust, Università Campus Bio-Medico di Roma, Universita Cattolica Del Sacro Cuore, Universität Ulm, University of Bern, University of Edinburgh, University of Hull, University of Leicester, University of Loughborough, University of Luxembourg, University of Manchester, University of Nottingham, Vlaams Brabant, Dienst Europa, Imperial College London, Boehringer Ingelheim, Breathomix, Gossamer Bio, AstraZeneca, CIBER, OncoRadiomics, University of Leiden, University of Wurzburg, Chiesi Pharmaceutical, University of Liege, Teva Pharmaceuticals, Sanofi, Pulmonary Fibrosis Foundation and Three Lakes Foundation. P.J. Sterk reports consultancy fees from SME Breathomix, and stock (or stock options) with SME Breathomix. S-E. Dahlen reports grants from AstraZeneca, GSK and Sanofi, consultancy fees from AstraZeneca, Cayman Chemicals, GSK and Regeneron, and payment or honoraria for lectures, presentations, manuscript writing or educational events from AstraZeneca, GSK and Sanofi. I.M. Adcock reports support for the present study from the Innovative Medicines Initiative, grants from GSK, MRC, EPSRC and Sanofi, consultancy fees from GSK, Sanofi, Chiesi and Kinaset, payment or honoraria for lectures, presentations, manuscript writing or educational events from AstraZeneca, Sanofi, Eurodrug and Sunovion, and support for attending meetings from AstraZeneca. S. Siddiqui consultancy fees from AstraZeneca, GSK, CSL Behring, Areteia Therapeutics, ERT Medical, Chiesi and Roche, and payment or honoraria for lectures, presentations, manuscript writing or educational events from GSK, Chiesi and AstraZeneca. P. Montuschi reports support for the present study from the Innovative Medicines Initiative. The remaining authors have no potential conflicts of interest to disclose., (Copyright ©The authors 2024.)

Asthma is a dynamic disease, in which lung mechanical and inflammatory processes interact in a complex manner, often resulting in exaggerated physiological, in particular, inflammatory responses to exogenous triggers. We hypothesize that this may be explained by respiratory disease-related systems instability and loss of adaptability to changing environmental conditions, manifested in highly fluctuating biomarkers and symptoms. Using time series of inflammatory (eosinophils, neutrophils, FeNO), clinical and lung function biomarkers (PEF, FVC,FEV 1 ), we estimated this loss of adaptive capacity (AC) during an experimental rhinovirus infection in 24 healthy and asthmatic human volunteers. Loss of AC was estimated by comparing similarities between pre- and post-challenge time series. Unlike healthy participants, the asthmatic's post-viral-challenge state resembled more other rhinovirus-infected asthmatics than their own pre-viral-challenge state (hypergeometric-test: p=0.029). This reveals loss of AC and supports the concept that in asthma, biological processes underlying inflammatory and physiological responses are unstable, contributing to loss of control., Competing Interests: AS, RL, BX, TD, BD, PS, UF, EE No competing interests declared, (© 2019, Sinha et al.)

Background: Although several studies link high levels of IL-6 and soluble IL-6 receptor (sIL-6R) to asthma severity and decreased lung function, the role of IL-6 trans-signaling (IL-6TS) in asthmatic patients is unclear., Objective: We sought to explore the association between epithelial IL-6TS pathway activation and molecular and clinical phenotypes in asthmatic patients., Methods: An IL-6TS gene signature obtained from air-liquid interface cultures of human bronchial epithelial cells stimulated with IL-6 and sIL-6R was used to stratify lung epithelial transcriptomic data (Unbiased Biomarkers in Prediction of Respiratory Disease Outcomes [U-BIOPRED] cohorts) by means of hierarchical clustering. IL-6TS-specific protein markers were used to stratify sputum biomarker data (Wessex cohort). Molecular phenotyping was based on transcriptional profiling of epithelial brushings, pathway analysis, and immunohistochemical analysis of bronchial biopsy specimens., Results: Activation of IL-6TS in air-liquid interface cultures reduced epithelial integrity and induced a specific gene signature enriched in genes associated with airway remodeling. The IL-6TS signature identified a subset of patients with IL-6TS-high asthma with increased epithelial expression of IL-6TS-inducible genes in the absence of systemic inflammation. The IL-6TS-high subset had an overrepresentation of frequent exacerbators, blood eosinophilia, and submucosal infiltration of T cells and macrophages. In bronchial brushings Toll-like receptor pathway genes were upregulated, whereas expression of cell junction genes was reduced. Sputum sIL-6R and IL-6 levels correlated with sputum markers of remodeling and innate immune activation, in particular YKL-40, matrix metalloproteinase 3, macrophage inflammatory protein 1β, IL-8, and IL-1β., Conclusions: Local lung epithelial IL-6TS activation in the absence of type 2 airway inflammation defines a novel subset of asthmatic patients and might drive airway inflammation and epithelial dysfunction in these patients., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: The association between secundum atrial septal defects (ASD) and asthma-like dyspnea with consequent long-term pulmonary inhalant use, is poorly understood in adult ASD patients. Airway hyperresponsiveness is suggested to be the underlying mechanism of cardiac asthma from mitral valve disease and ischemic cardiomyopathy. We hypothesized that airway hyperresponsiveness may also be found in adult ASD patients. Our aim was to study airway responsiveness in adult ASD patients before percutaneous closure and at short-and long-term postprocedural follow-up., Methods: This prospective study included 31 ASD patients (65% female, mean age 49 ± 15y) who underwent spirometry and bronchoprovocation testing pre-and six-month postprocedurally, with additional bronchoprovocation at 2-year follow-up. Airway hyperresponsiveness was defined as ≥20% fall of forced expiratory volume in 1-second (FEV 1 ) following <8.0 mg/mL of inhaled methacholine., Results: Airway hyperresponsiveness was found in 19/30 patients (63%[95%CI 45%-81%]; post hoc statistical power = 89%). Asthma-like symptoms wheezing, chest tightness, and cough were more frequently reported in airway hyperresponsive patients. Airway responsiveness was not influenced by successful percutaneous ASD closure, corresponding to persistence of asthma-like symptoms postclosure. Regardless of airway responsiveness, postprocedural right-sided reverse remodeling significantly improved dyspnea and pulmonary function., Conclusions: This study is the first to report a high prevalence of airway hyperresponsiveness in a cohort of unrepaired adult ASD patients, and confirms the association between asthma-like symptoms and ASD in adults. Attention to symptoms and pulmonary function should be given during clinical follow-up of adult ASD patients, both before and long after repair., (© 2018 The Authors. Congenital Heart Disease Published by Wiley Periodicals, Inc.)

Background: Post-repair atrial septal defects (ASD) patients are frequently discharged from follow-up, but the extent of pulmonary symptoms long-term post-repair is unknown., Methods and results: The national CONgenital CORvitia registry was linked to the national Drug Registry to investigate all ambulatory-dispensed pulmonary inhalants for 2006-2014. ASD patients were compared with age- and sex-matched referents from the general population. A total of 1,959 adult patients (age 42±17 years; 66% female; 1,223 [62%] repaired) were included. Compared with the referents, ASD patients had more inhalant use, even at long-term post-repair follow-up (OR=1.81 [95% CI 1.62-2.03]; P<0.001)., Conclusions: ASD patients had 2-fold higher inhalant use compared with referents even at long-term post-repair follow-up, suggesting persistent pulmonary functional impairment.

Background: Lung epithelial lining fluid (ELF)-sampled through sputum induction-is a medium rich in cells, proteins and lipids. However, despite its key role in maintaining lung function, homeostasis and defences, the composition and biology of ELF, especially in respect of lipids, remain incompletely understood., Objectives: To characterise the induced sputum lipidome of healthy adult individuals, and to examine associations between different ELF lipid phenotypes and the demographic characteristics within the study cohort., Methods: Induced sputum samples were obtained from 41 healthy non-smoking adults, and their lipid compositions analysed using a combination of untargeted shotgun and liquid chromatography mass spectrometry methods. Topological data analysis (TDA) was used to group subjects with comparable sputum lipidomes in order to identify distinct ELF phenotypes., Results: The induced sputum lipidome was diverse, comprising a range of different molecular classes, including at least 75 glycerophospholipids, 13 sphingolipids, 5 sterol lipids and 12 neutral glycerolipids. TDA identified two distinct phenotypes differentiated by a higher total lipid content and specific enrichments of diacyl-glycerophosphocholines, -inositols and -glycerols in one group, with enrichments of sterols, glycolipids and sphingolipids in the other. Subjects presenting the lipid-rich ELF phenotype also had significantly higher BMI, but did not differ in respect of other demographic characteristics such as age or gender., Conclusions: We provide the first evidence that the ELF lipidome varies significantly between healthy individuals and propose that such differences are related to weight status, highlighting the potential impact of (over)nutrition on lung lipid metabolism.

Worldwide, the number of professional and sports divers is increasing. Most of them breathe diving gases with a raised partial pressure of oxygen (P O 2 ). However, if the P O 2 is between 50 and 300 kPa (375-2250 mmHg) (hyperoxia), pathological pulmonary changes can develop, known as pulmonary oxygen toxicity (POT). Although in its acute phase, POT is reversible, it can ultimately lead to non-reversible pathological changes. Therefore, it is important to monitor these divers to prevent them from sustaining irreversible lesions.This review summarises the pulmonary pathophysiological effects when breathing oxygen with a P O 2 of 50-300 kPa (375-2250 mmHg). We describe the role and the limitations of lung function testing in monitoring the onset and development of POT, and discuss new techniques in respiratory medicine as potential markers in the early development of POT in divers., (Copyright ©ERS 2016.)

Volatile organic compounds (VOCs) are produced by virtually all metabolic processes of the body. As such, they have potential to serve as noninvasive metabolic biomarkers. Since exhaled VOCs are either derived from the respiratory tract itself or have passed the lungs from the circulation, they are candidate biomarkers in the diagnosis and monitoring of pulmonary diseases in particular. Good examples of the possibilities of exhaled volatiles in pulmonary medicine are provided by the potential use of VOCs to discriminate between patients with lung cancer and healthy control subjects and to noninvasively diagnose infectious diseases and the association between VOCs and markers of disease activity that has been established in obstructive lung diseases. Several steps are, however, required prior to implementation of breath-based diagnostics in daily clinical practice. First, VOCs should be studied in the intention-to-diagnose population, because biomarkers are likely to be affected by multiple (comorbid) conditions. Second, breath collection and analysis procedures need to be standardized to allow pooling of data. Finally, apart from probabilistic analysis for diagnostic purposes, detailed examination of the nature of volatile biomarkers not only will improve our understanding of the pathophysiologic origins of these markers and the nature of potential confounders but also can enable the development of sensors that exhibit maximum sensitivity and specificity toward specific applications. By adhering to such an approach, exhaled biomarkers can be validated in the diagnosis, monitoring, and treatment of patients in pulmonary medicine and contribute to the development of personalized medicine.

Introduction: To prevent extensive pulmonary lesions in submerged oxygen divers lung function like the forced vital capacity (FVC) or the diffusing capacity for carbon monoxide (DL,co) are used to monitor pulmonary oxygen toxicity (POT). As the diffusing capacity for nitric oxide (DL,no) measures more accurately the membrane diffusing capacity compared to DL,co we hypothesized that DL,no is superior in monitoring the onset of physiological changes indicative of POT as compared to DL,co or FVC., Method: 26 healthy divers (mean age 30.7 ± 6.2 years) made two submerged dives to 190 kPa for 1 h on two randomized separate days, whilst breathing 100% oxygen or compressed air. FVC, DL,no, DL,co and alveolar volume (VA ) were measured 6 times during a 26-h period., Results: Up to 8 h no significant differences in outcomes were found between the oxygen and air dives. However, at 8 h after the oxygen dives there was a significant reduction in DL,no, DL,co and VA as compared with air dives. In contrast, the reduction in FVC was significantly greater after the air dive. At 22 h there were no longer differences in outcomes between the dives., Conclusions: These data show that DL,no and DL,co are significantly reduced 8 h after submerged oxygen dives as compared to similar air dives. Together with the reduction in VA this may be indicative of interstitial edema as an early sign of POT. Our data warrant validation of the superiority of DL,no and DL,co over FVC in the practical monitoring of divers., (© 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.)

Background: Chronic mucus hypersecretion (CMH) is associated with an increased frequency of respiratory infections, excess lung function decline, and increased hospitalisation and mortality rates in the general population. It is associated with smoking, but it is unknown why only a minority of smokers develops CMH. A plausible explanation for this phenomenon is a predisposing genetic constitution. Therefore, we performed a genome wide association (GWA) study of CMH in Caucasian populations., Methods: GWA analysis was performed in the NELSON-study using the Illumina 610 array, followed by replication and meta-analysis in 11 additional cohorts. In total 2,704 subjects with, and 7,624 subjects without CMH were included, all current or former heavy smokers (≥20 pack-years). Additional studies were performed to test the functional relevance of the most significant single nucleotide polymorphism (SNP)., Results: A strong association with CMH, consistent across all cohorts, was observed with rs6577641 (p = 4.25×10(-6), OR = 1.17), located in intron 9 of the special AT-rich sequence-binding protein 1 locus (SATB1) on chromosome 3. The risk allele (G) was associated with higher mRNA expression of SATB1 (4.3×10(-9)) in lung tissue. Presence of CMH was associated with increased SATB1 mRNA expression in bronchial biopsies from COPD patients. SATB1 expression was induced during differentiation of primary human bronchial epithelial cells in culture., Conclusions: Our findings, that SNP rs6577641 is associated with CMH in multiple cohorts and is a cis-eQTL for SATB1, together with our additional observation that SATB1 expression increases during epithelial differentiation provide suggestive evidence that SATB1 is a gene that affects CMH.

Exhaled breath contains information on systemic and pulmonary metabolism, which may provide a monitoring tool for the development of lung injury. We aimed to determine the effect of intravenous (iv) and intratracheal (IT) lipopolysaccharide (LPS) challenge on the exhaled mixture of volatile metabolites and to assess the similarities between these two models. Male adult Sprague-Dawley rats were anesthetized, tracheotomized, and ventilated for 6 h. Lung injury was induced by iv or IT administration of LPS. Exhaled breath was monitored continuously using an electronic nose (eNose), and hourly using gas chromatography and mass spectrometry (GC-MS). GC-MS analysis identified 34 and 14 potential biological markers for lung injury in the iv and IT LPS models, respectively. These volatile biomarkers could be used to discriminate between LPS-challenged rats and control animals within 1 h after LPS administration. Electronic nose analysis resulted in a good separation 3 h after the LPS challenge. Hexanal, pentadecane and 6,10-dimethyl-5,9-undecadien-2-one concentrations decreased after both iv and IT LPS administration. Nonanoic acid was found in a higher concentration in exhaled breath after LPS inoculation into the trachea but in a lower concentration after iv infusion. LPS-induced lung injury rapidly changes exhaled breath metabolite mixtures in two animal models of lung injury. Changes partly overlap between an iv and an IT LPS challenge. This warrants testing the diagnostic accuracy of exhaled breath analysis for acute respiratory distress syndrome in clinical trials, possibly focusing on biological markers described in this study.

When breathing oxygen with partial oxygen pressures PO₂ of between 50 and 300 kPa pathological pulmonary changes develop after 3-24h depending on the PO₂. This kind of injury (known as pulmonary oxygen toxicity) is not only observed in ventilated patients but is also considered an occupational hazard in oxygen divers or mixed gas divers. To prevent these latter groups from sustaining irreversible lesions adequate prevention is required. This review summarizes the pathophysiological effects on the respiratory tract when breathing oxygen with PO₂ of 50-300 kPa (hyperoxia). We discuss to what extent the most commonly used lung function parameters change after exposure to hyperoxia and its role in monitoring the onset and development of pulmonary oxygen toxicity in daily practice. Finally, new techniques in respiratory medicine are discussed with regard to their usefulness in monitoring pulmonary oxygen toxicity in divers., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Rationale: Breathing oxygen with a partial pressure of > 50 kPa can cause pulmonary oxygen toxicity (POT). Diffusing capacity for carbon monoxide (DL(CO)) is thought to be a more sensitive indicator of POT than vital capacity (VC). Because diffusing capacity can be measured more specifically using nitric oxide (DL(NO)), we hypothesized that DL(NO) is better able to monitor and exclude POT than DL(CO)., Objective: To compare changes in lung function after oxygen and air dives which include measurement of DL(NO) and DL(CO)., Method: Eleven healthy male divers (mean age 27.5 +/- 3.1 years) made two immersed dives to 150 kPa for three hours on two separate days, during which they randomly breathed 100% oxygen or air. VC, DL(NO) and DL(CO) were measured six times during a 26-hour period on both days and on a third non-diving day., Results: There were no significant changes in DL(CO), DL(NO) or other diffusing capacity or spirometric parameters after either type of dive., Conclusion: Lung function after a single three-hour oxygen dive at a pO2 of approximately 150 kPa is comparable to that after an air dive at the same depth and duration. This suggests that such an oxygen dive does not induce detectable signs of POT. Our hypothesis that DL(NO) is more sensitive than DL(CO) for detection of POT could not be tested because the oxygen exposure did not affect either parameter.

Rationale: Breathing oxygen with a partial pressure of >50 kPa causes pulmonary oxygen toxicity (POT), resulting in a decrease in vital capacity (VC) and in diffusing capacity for carbon monoxide (DLco). As submersion is thought to potentiate POT, we hypothesized that submerged oxygen divers are at increased risk for POT., Objective: To compare changes in lung function after submerged (wet) and non-submerged (dry) oxygen dives., Method: Thirteen healthy male divers (mean ± SD: 25 ± 2 years, 184 ± 7 cm, 85 ± 10 kg) made a dry and a wet dive to 150 kPa for 3 h, during which they breathed 100% oxygen. At baseline, within 1 and 4 h after their dives, spirometry and diffusing capacity were measured. Data were analysed with ANOVA using Bonferroni correction and paired t-tests., Results: Compared with baseline, there was a significant reduction in DLco (-1·6 mmol kPa(-1) min(-1)) after a wet oxygen dive but not after a dry dive. In addition, relative to baseline, there was a significant difference in ΔDLco and ΔVC when comparing wet and dry oxygen dives., Conclusion: Diffusing capacity is more impaired after a wet oxygen dive than after a dry one. This suggests that wet oxygen divers are at increased risk for POT. Monitoring studies during daily practice of professional divers are mandatory to determine the exact operational relevance of the present findings., (© 2011 The Authors. Clinical Physiology and Functional Imaging © 2011 Scandinavian Society of Clinical Physiology and Nuclear Medicine.)

Background: Airway remodelling is a feature of asthma including fragmentation of elastic fibres observed in the superficial elastin network of the airway wall. Fibered confocal fluorescence microscopy (FCFM) is a new and non-invasive imaging technique performed during bronchoscopy that may visualize elastic fibres, as shown by in vitro spectral analysis of elastin powder. We hypothesized that FCFM images capture in vivo elastic fibre patterns within the airway wall and that such patterns correspond with airway histology. We aimed to establish the concordance between the bronchial elastic fibre pattern in histology and FCFM. Second, we examined whether elastic fibre patterns in histology and FCFM were different between asthmatic subjects and healthy controls. Finally, the association between these patterns and lung function parameters was investigated., Methods: In a cross-sectional study comprising 16 subjects (8 atopic asthmatic patients with controlled disease and 8 healthy controls) spirometry and bronchoscopy were performed, with recording of FCFM images followed by endobronchial biopsy at the airway main carina. Elastic fibre patterns in histological sections and FCFM images were scored semi-quantitatively. Agreement between histology and FCFM was analysed using linearly weighted kappa κw., Results: The patterns observed in histological sections and FCFM images could be divided into 3 distinct groups. There was good agreement between elastic fibre patterns in histology and FCFM patterns (κw 0.744). The semi-quantitative pattern scores were not different between asthmatic patients and controls. Notably, there was a significant difference in post-bronchodilator FEV1 %predicted between the different patterns by histology (p = 0.001) and FCFM (p = 0.048), regardless of asthma or atopy., Conclusion: FCFM captures the elastic fibre pattern within the airway wall in humans in vivo. The association between post-bronchodilator FEV1 %predicted and both histological and FCFM elastic fibre patterns points towards a structure-function relationship between extracellular matrix in the airway wall and lung function., Trial Registration: Netherlands Trial Register NTR1306.

The lung is a highly complex organ that can only be understood by integrating the many aspects of its structure and function into a comprehensive view. Such a view is provided by a systems biology approach, whereby the many layers of complexity, from the molecular genetic, to the cellular, to the tissue, to the whole organ, and finally to the whole body, are synthesized into a working model of understanding. The systems biology approach therefore relies on the expertise of many disciplines, including genomics, proteomics, metabolomics, physiomics, and, ultimately, clinical medicine. The overall structure and functioning of the lung cannot be predicted from studying any one of these systems in isolation, and so this approach highlights the importance of emergence as the fundamental feature of systems biology. In this paper, we will provide an overview of a systems biology approach to lung disease by briefly reviewing the advances made at many of these levels, with special emphasis on recent work done in the realm of pulmonary physiology and the analysis of clinical phenotypes.

Asthma and COPD are chronic respiratory diseases that fluctuate widely with regard to clinical symptoms and airway obstruction, complicating treatment and prediction of exacerbations. Time series of respiratory impedance obtained by the forced oscillation technique are a convenient tool to study the respiratory system with high temporal resolution. In previous studies it was suggested that power-law-like fluctuations exist also in the healthy lung and that respiratory system impedance variability differs in asthma. In this study we elucidate such differences in a population of well-characterized subjects with asthma (n = 13, GINA 1+2), COPD (n = 12, GOLD I+II), and controls (n = 10) from time series at single frequency (12 min, f = 8 Hz). Maximum likelihood estimation did not rule out power-law behavior, accepting the null hypothesis in 17/35 cases (P > 0.05) and with significant differences in exponents for COPD (P < 0.03). Detrended fluctuation analysis exhibited scaling exponents close to 0.5, indicating few correlations, with no differences between groups (P > 0.14). In a second approach, we considered asthma and COPD as dynamic diseases, corresponding to changes of unknown parameters in a deterministic system. The similarity in shape between the combined probability distributions of normalized resistance and reactance was quantified by Wasserstein distances and reliably distinguished the two diseases (cross-validated predictive accuracy 0.80; sensitivity 0.83, specificity 0.77 for COPD). Wasserstein distances between 3+3 dimensional phase space reconstructions resulted in marginally better classification (accuracy 0.84, sensitivity 0.83, specificity 0.85). These latter findings suggest that the dynamics of respiratory impedance contain valuable information for the diagnosis and monitoring of patients with asthma and COPD, whereas the value of the stochastic approach is not clear presently.

Background: Inhaled corticosteroids (ICSs) and long-acting beta(2)-agonists (LABAs) are used to treat moderate to severe chronic obstructive pulmonary disease (COPD)., Objective: To determine whether long-term ICS therapy, with and without LABAs, reduces inflammation and improves pulmonary function in COPD., Design: Randomized, placebo-controlled trial. (ClinicalTrials.gov registration number: NCT00158847), Setting: 2 university medical centers in The Netherlands., Patients: 114 steroid-naive current or former smokers with moderate to severe COPD., Measurements: Cell counts in bronchial biopsies and sputum (primary outcome); methacholine responsiveness at baseline, 6, and 30 months; and clinical outcomes every 3 months., Intervention: Random assignment by minimization method to receive fluticasone propionate, 500 microg twice daily, for 6 months (n = 31) or 30 months (n = 26); fluticasone, 500 microg twice daily, and salmeterol, 50 microg twice daily, for 30 months (single inhaler; n = 28); or placebo twice daily (n = 29)., Results: 101 patients were greater than 70% adherent to therapy. Fluticasone therapy decreased counts of mucosal CD3(+) cells (-55% [95% CI, -74% to -22%]; P = 0.004), CD4(+) cells (-78% [CI, -88% to 60%]; P < 0.001), CD8(+) cells (-57% [CI, -77% to -18%]; P = 0.010), and mast cells (-38% [CI, -60% to -2%]; P = 0.039) and reduced hyperresponsiveness (P = 0.036) versus placebo at 6 months, with effects maintained after 30 months. Fluticasone therapy for 30 months reduced mast cell count and increased eosinophil count and percentage of intact epithelium, with accompanying reductions in sputum neutrophil, macrophage, and lymphocyte counts and improvements in FEV(1) decline, dyspnea, and quality of life. Reductions in inflammatory cells correlated with clinical improvements. Discontinuing fluticasone therapy at 6 months increased counts of CD3(+) cells (120% [CI, 24% to 289%]; P = 0.007), mast cells (218% [CI, 99% to 407%]; P < 0.001), and plasma cells (118% [CI, 9% to 336%]; P = 0.028) and worsened clinical outcome. Adding salmeterol improved FEV(1) level., Limitations: The study was not designed to evaluate clinical outcomes. Measurement of primary outcome was not available for 24% of patients at 30 months., Conclusion: ICS therapy decreases inflammation and can attenuate decline in lung function in steroid-naive patients with moderate to severe COPD. Adding LABAs does not enhance these effects. .

Deep inspiration temporarily reduces induced airways obstruction in healthy subjects. This bronchodilatory effect of deep inspiration is impaired in asthma. Passive machine-assisted lung inflation may augment bronchodilation compared with an active deep inspiration in patients with asthma by either opening closed airways or by reducing fluid flux across the airway wall during deep inspiration, and thereby increasing the tethering forces on the airway wall. We recruited 24 patients with asthma [18-46 yr old, forced expiratory volume in 1 s (FEV(1)) > 70% predicted; provocative concentration of methacholine inducing a 20% fall in FEV(1) (PC(20)) < 8 mg/ml], with either an impaired (n = 12) or an intact (n = 12) bronchodilatory response to deep inspiration. Two methacholine challenges were performed on separate days. At a 50% increase in respiratory resistance (forced oscillation technique at 8 Hz), the change in resistance by a positive-pressure inflation (computer-driven syringe) or an active deep inspiration was measured in randomized order. The reduction in resistance by positive-pressure inflation was significantly greater than by active deep inspiration in the impaired deep inspiration response group (mean change +/- SE: -0.6 +/- 0.1 vs. -0.03 +/- 0.2 cmH(2)O.l(-1).s, P = 0.002). No significant difference was found between positive-pressure inflation and active deep inspiration in the intact deep inspiration response group (-0.6 +/- 0.2 vs. -1.0 +/- 0.3 cmH(2)O.l(-1).s, P = 0.18). Positive-pressure inflation of the lungs can significantly enhance deep inspiration-induced bronchodilation in patients with asthma.

Background: Asthma and obesity are associated disorders, but the contribution of obesity to difficult-to-treat asthma as well as the mechanisms responsible for this relationship are unclear. The aim of this study was to investigate the relationship between obesity (body mass index >/= 30) and factors related with asthma severity in patients with difficult-to-treat asthma., Methods: One hundred and thirty-six nonsmoking asthmatic adults with persistent symptoms despite high doses of inhaled or oral corticosteroids and long-acting bronchodilators were studied [70% female, median (range) age 44.6 (18-75) years, 32% on daily oral corticosteroids]. The association between obesity, lung function parameters [forced expiratory volume in 1 s (FEV(1)), functional residual capacity/total lung capacity (FRC/TLC)], inflammatory markers [blood eosinophils, sputum eosinophils and neutrophils, exhaled nitric oxide (FE(NO)), airway hyperresponsiveness, C-reactive protein (CRP)] and aggravating co-morbid factors (severe chronic sinus disease, gastro-esophageal reflux, recurrent respiratory infections, psychopathology and obstructive sleep apnea) was investigated., Results: Obese patients (n = 29) had a higher FEV(1)%pred (P = 0.05) and a lower FRC/TLC%pred (P < 0.01) compared with nonobese patients (n = 107). Body mass index was inversely related with sputum eosinophils (r = -0.36, P < 0.01) and FE(NO) (r = -0.30, P < 0.01). Obese patients had an increased risk for gastro-esophageal reflux (OR = 2.3) and sleep apnea (OR = 3.1)., Conclusion: Obesity in patients with difficult-to-treat asthma is inversely related with sputum eosinophils and FE(NO), and positively associated with the presence of co-morbid factors and reduced lung volumes. This suggests that other factors than airway inflammation alone explain the relationship between obesity and asthma severity.

Background: Smoking induces structural changes in the airways, and is considered a major factor in the development of airflow obstruction in chronic obstructive pulmonary disease. However, differences in inflammatory cell distribution between large airways (LA) and small airways (SA) have not been systematically explored in smokers., Hypothesis: The content of cells infiltrating the airway wall differs between LA and SA., Aims: To compare the content of neutrophils, macrophages, lymphocytes and mast cells infiltrating LA and SA in smokers who underwent surgery for lung cancer., Methods: Lung tissue from 15 smokers was analysed. Inflammatory cells in the lamina propria were identified by immunohistochemical analysis, quantified by digital image analysis and expressed as number of cells per surface area., Results: The number of neutrophils infiltrating the lamina propria of SA (median 225.3 cells/mm(2)) was higher than that in the lamina propria of LA (median 60.2 cells/mm(2); p<0.001). Similar results were observed for mast cells: 313.3 and 133.7 cells/mm(2) in the SA and LA, respectively (p<0.001). In contrast, the number of CD4 cells was higher in LA compared with SA (median 217.8 vs 80.5 cells/mm(2); p = 0.042)., Conclusions: These findings indicate a non-uniform distribution of neutrophils and mast cells throughout the bronchial tree, and suggest that these cells may be involved in the development of smoking-related peripheral lung injury.

Adhesion molecule very late antigen-4 (VLA-4) is implicated in the recruitment and activation of inflammatory cells in asthma, including eosinophils, T cells and mast cells. VLA-4 antagonists have been proposed as a new anti-inflammatory treatment modality for asthma. Therefore, we investigated whether a single inhaled dose of VLA-4 antagonist GW559090X could protect against allergen-induced changes in airway responses and airway inflammation in patients with asthma. We performed a randomized, double-blind, three-way crossover study with single inhaled doses of 3 mg of GW559090X, 500 microg of fluticasone propionate (FP) or placebo in 15 patients with mild intermittent asthma, controlled with short-acting beta(2)-agonists only. All patients developed a late asthmatic response (LAR) after allergen inhalation during screening. Study medication was administered 30 min prior to allergen challenge. Pre-dose and 24 h post-dose PC20 methacholine and levels of exhaled nitric oxide (eNO) were determined. At the given dose, VLA-4 antagonist GW559090X did not attenuate the early asthmatic response (EAR) when compared with placebo: mean AUC0-2 h(+/-SEM) (%fall h): 27.2+/-3.7 and 21.9+/-3.0 respectively (P=0.33); nor the LAR: mean AUC3-8 h(+/-SEM) (%fall h): 98.8+/-12.9 and 94.8+/-6.8 respectively (P=0.84). However, pretreatment with FP did attenuate both EAR and LAR when compared with placebo: mean AUC0-2 h11.6+/-3.3 (P=0.024) and mean AUC3-8 h 6.3+/-7.6 (P<0.001). None of these treatments had an effect on allergen-induced changes in airway hyper-responsiveness or eNO levels. These findings suggest that VLA-4 may not play a major role in allergen-induced airway responses and inflammation in asthma.

Background: The mechanisms leading to death from asthma are not completely understood. Recent studies suggest the involvement of the anaphylatoxins C3a and C5a, generated during complement activation, and their receptors C3aR and C5aR in the pathogenesis of asthma., Objective: The aim of our study was to investigate the expression of C3aR and C5aR in fatal asthma., Methods: We analyzed lung tissue from 14 subjects who died of asthma (fatal asthma; FA) and 14 subjects who died of nonpulmonary causes (controls) and bronchial biopsy specimens from 16 subjects with mild intermittent asthma (MIA). C3aR and C5aR expression was evaluated by immunohistochemistry, and a semiquantitative analysis of the intensity of staining was performed according to a visual analogue scale (score, 0-3)., Results: C3aR was expressed on airway epithelium, smooth muscle, submucosal, and parenchymal vessels. C5aR was expressed on myeloid cells infiltrating the submucosa and on airway epithelium. Statistical analysis demonstrated higher expression of C3aR on submucosal vessels in FA compared with controls and MIA (median [minimum-maximum], controls, 0.24 [0-1.48]; MIA, 0.0 [0-1.00]; FA, 1.56 [0.13-3]; P = .002). C3aR was also increased on parenchymal vessels in FA (controls, 0.56 [0-2.00]; FA, 1.81 [0.5-3]; P = .0004). C5aR expression on airway epithelium was increased in FA compared with controls and MIA (controls, 1.25 [0.25-3]; MIA, 1.00 [0-2.00]; FA, 3.00 [1.13-3.00]; P = .001)., Conclusion: The results of our study suggest a role of complement in FA.

Background: Persistent airflow limitation may develop in patients with asthma, particularly in adults with nonatopic (intrinsic) disease. Although the underlying mechanisms are still unknown, respiratory infections might be involved., Objective: We investigated the annual loss of lung function in relation to seropositivity to Chlamydia pneumoniae in different subgroups of patients with severe asthma according to age at onset of asthma and atopic status., Methods: One hundred one nonsmoking outpatients with a pulmonologist's diagnosis of severe asthma (32 men and 69 women; mean age, 46.0 years; range, 18-75 years) were included in a cross-sectional study. C pneumoniae-specific serum IgG and IgA were measured by means of ELISA. The estimated decline in lung function was calculated from the relationship between postbronchodilator FEV(1)/vital capacity (percent predicted) and the duration of asthma and expressed as the slope of the regression line., Results: Patients with adult-onset nonatopic asthma and positive IgG antibodies to C pneumoniae had a significantly steeper slope of the regression line compared with the other subgroups of asthmatic patients (P =.001), being indicative of a 4-fold greater estimated decline in postbronchodilator FEV(1)/vital capacity (2.3% vs 0.5% predicted per year of asthma duration)., Conclusion: These results suggest that C pneumoniae infection might promote the development of persistent airflow limitation in patients with nonatopic adult-onset asthma. It remains to be established whether viable pathogens that are accessible for therapeutic intervention are still present in the lower airways.

We postulated that the distinct pathophysiologic mechanisms of airway narrowing during the early (EAR) and the late (LAR) asthmatic responses to inhaled allergens are reflected by the generation or transmission of lung sounds in asthma. Therefore, we measured FEV1 and recorded lung sounds in eight mildly asthmatic subjects before a standardized allergen challenge (PRE), during the EAR, during the recovery phase at 2 h (MID), during the LAR at 7 h, and after inhalation of a bronchodilator (POST). The recordings were made during flow- and volume-standardized quiet breathing, and during maximal forced breathing maneuvers. Airflow-dependent power spectra were analyzed for lung sound intensity (LSI), quartile power points (Q25, Q50, Q75), and extent of wheezing (W). These sound characteristics were compared among the various stages of the challenge in the presence (EAR, LAR) and absence (PRE, MID, POST) of acute airway obstruction using ANOVA. LSI, Q25 - Q75, and W were all elevated during airway obstruction. When matched for percent fall in FEV1, during the EAR and the LAR (mean +/- SD: 26.7 +/- 4.0, and 28.9 +/- 5.7, respectively; p = 0.385), the increase in Q25, and Q50 with airflow during quiet expiration, as well as the extent of wheezing, were higher during the LAR than during the EAR (p < or = 0.042 and p < or = 0.012, respectively). At similar levels of FEV1 (p > or = 0.156), LSI on expiration was higher at POST than at PRE or MID (p < or = 0.067), whereas Q25 (p < or = 0.047) and Q50 (p < or = 0.064) were lower at POST than at PRE. During forced expiration W was higher at MID and POST than at PRE (p < or = 0.014). We conclude that LSI, frequency content, and the extent of wheezing vary during the subsequent stages of allergen-induced bronchoconstriction in asthma despite matched values of FEV1. This suggests that airflow-standardized phonopneumography is a sensitive method for detecting differences in the pathophysiology of airway narrowing in asthma.

The prevalence of abnormalities in lung elasticity in patients with asthma or chronic obstructive pulmonary disease (COPD) is still unclear. This might be due to uncertainties concerning the method of analysis of quasistatic deflation lung pressure-volume curves. Pressure-volume curves were obtained in 99 patients with moderately severe asthma or COPD. These patients were a subgroup from a Dutch multicentre trial; the entire group was selected on the basis of a moderately lowered % predicted forced expiratory volume in one second (FEV1), and a provocative concentration of histamine producing a 20% decrease in FEV1 (PC20) < 8 mg.mL-1 obtained with the 2 min tidal breathing technique. The curves were fitted with an exponential (E) model and an exponential model which took the linear appearance in the mid vital capacity range into account (linear-exponential (LE)). The linear-exponential model showed a markedly better fit ability, yielding additional parameters, such as the compliance at functional residual capacity (FRC) level as slope of the linear part (b), and the volume at which the linear part changed into the exponential part of the curve (transition volume (Vtr)). Vtr (mean value Vtr/total lung capacity (TLC) = 0.79 (SD 0.07)) showed a close positive linear correlation with obstruction and hyperinflation variables, which might be due to airway closure, already starting at elevated lung volumes. The exponential shape factor K was closely correlated with b and mean values (K = 1.32 (SD 0.05) kPa-1; b = 2.96 (SD 1.16) L,kPa-1) and the relationship with age was comparable with data reported in healthy individuals. The shape factor of the linear-exponential fit showed no correlation with any elasticity related variable. Neither the elastic recoil at 90% TLC, as obtained from the linear-exponential fit, nor its relationship with age were significantly different from healthy individuals. We conclude that, for a more accurate description of the lung pressure-volume curve, a linear-exponential fit is preferable to an exponential model. However, the physiological relevance of the shape parameter (KLE) is still unclear. These results indicate that patients with moderately severe asthma or COPD had, on average, no appreciable loss of elastic lung recoil as compared with healthy individuals.

Purpose: Combination chemotherapy regimens that include cisplatin (CDDP) and bleomycin (BLE) result in the cure of the majority of patients with malignant germ cell tumors of the testis. We investigated the long-term damage of such chemotherapy to renal, pulmonary, and hearing function., Patients and Methods: Forty-three patients with disseminated testicular carcinoma were studied 1.5 to 9.3 years (median, 4.1 years) after completion of chemotherapy. All 43 patients received CDDP; of these, 39 also received BLE, 27 vinblastine (VLB), and 27 etoposide (VP-16). Mean cumulative doses of individual cytotoxic drugs administered were CDDP 483 mg/m2 (range, 189 to 1,173 mg/m2), BLE 160 mg/m2 (range, 81 to 311 mg/m2), VLB 31 mg/m2 (range, 19 to 158 mg/m2), and VP-16 667 mg/m2 (range, 242 to 1,455 mg/m2)., Results: In the majority of cases, values of renal, pulmonary, and hearing function were within the normal range before treatment. An initial decrease in renal, pulmonary, and hearing function was observed, with recovery of pulmonary function at late follow-up. On average, a decrease of 15% in creatinine clearance rates was observed at late follow-up. Long-term effect on audiometric function was considerable, but frequencies affected were outside the range of conversational speech. With multivariate analysis, no overall relation between the cumulative doses of the individual drugs and the loss in organ function was found; the cumulative doses of CDDP and BLE only contributed approximately 30% to the loss in renal function and vital capacity, respectively., Conclusion: Chemotherapy-induced pulmonary toxicity is reversible, whereas nephrotoxicity and ototoxicity are not. However, the long-term effects of chemotherapy in testicular cancer patients were minor and not invalidating.

Exercise training has been considered suitable only in cystic fibrosis (CF) patients with mild to moderate pulmonary dysfunction without progressive hypoxaemia during exercise. We trained 16 CF patients, all with advanced lung disease (mean standardized forced expiratory volume in 1 s (FEV1), 30% pred.), with a ventilatory limitation to exercise and a progressive hypoxaemia and hypercapnia at low maximal exercise capacity, Wmax (mean Wmax, 50% pred). Exercise training was performed on a cycle ergometer twice a day for 20 min at approximately 75% of the maximal predicted heart rate for at least 3 weeks. Supplemental oxygen was administered to reach a haemoglobin oxygen saturation of 90% during training. Patients considered malnourished because of a Quetelet Index of less than 20 kg m-2 received hyperalimentation orally or by duodenal tube (total 3500-4000 kcal day-1). Evaluation directly after the training period showed a statistically significant improvement in Wmax, maximal oxygen consumption, maximal minute ventilation, pulse, PaCO2 at rest, FEV1 and body weight. None of the pretraining variables was able to predict the outcome of the training programme in the individual patient. We detected no adverse effects of the programme. This study shows that oxygen-assisted exercise training in combination with correction of the nutritional status is safe and beneficial in CF patients with severe lung disease.

We investigated whether or not leukotriene D4 can influence the maximal degree of airway narrowing in normal humans by comparing the maximal responses to inhaled methacholine and LTD4, and evaluating the interaction between both agonists. In 8 normal subjects, methacholine challenges were performed 24 h before and 24 and 72 h after a LTD4 challenge. Doubling doses of methacholine (1.3 to 655 mumol) or LTD4 (0.007 to 192 nmol) were inhaled by using a recently validated method. The highest dose of LTD4 was followed by the maximal dose of methacholine. The response was measured by FEV1 and volume history standardized partial expiratory flow-volume curves (V40p), and was expressed as percent fall from baseline. All subjects reached a maximal response plateau to both agonists. The maximal response plateau to LTD4 was systematically higher than to methacholine on the preceding day (mean difference, 13.4 and 12.7% fall for FEV1 and V40p, respectively) (p less than 0.01). Addition of methacholine on top of the LTD4 plateau caused a further increase in the response (mean, 6.6 and 4.8% fall, respectively) (p less than 0.005). The maximal responses to methacholine at 24 and 72 h after the LTD4 challenge were higher than at 24 h before (mean difference at 24 h, 4.0 and 8.5% fall for FEV1 and V40p, respectively, and at 72 h 5.7 and 9.3% fall) (p less than 0.05). However, the provocative dose of methacholine causing a 10% fall in FEV1 (PD10) or a 40% fall in V40p (PD40) was not altered by the previous LTD4 challenge test.(ABSTRACT TRUNCATED AT 250 WORDS)

In normal humans in vivo, maximal airway narrowing to LTD4 is more severe than to methacholine. Moreover, LTD4 heightens the maximal response to methacholine for several days. To investigate whether or not this is due to inflammatory changes in the airway wall, we studied the effects of the corticosteroid budesonide on the dose-response curves to inhaled LTD4 and to methacholine. In a two-period, double-blind, placebo-controlled design, budesonide (400 micrograms twice a day) or placebo was inhaled by eight normal subjects on six consecutive days, with a 3-wk washout. Complete dose-response curves to LTD4 (0.36 to 43 nmol) were performed on Day 5, and to methacholine (1.28 to 655 mumol) on Days 4 and 6 of each period using a validated method. The response was measured by FEV1 and standardized partial expiratory flow-volume curves (V40p), and was expressed as the percent fall from baseline. A maximal response plateau was considered if more than two doses fell within a 5% response range. All subjects reached plateaus to methacholine and to LTD4. Budesonide reduced the maximal response to LTD4 (mean difference with placebo, 7.9% fall for FEV1, and 8.4% fall for V40p; p less than 0.05). During placebo the maximal response to methacholine 24 h after LTD4 was higher than 24 h before (mean change, 2.7% fall in FEV1 and 5.5% fall in V40p; p less than 0.05), but not during budesonide (mean change, -2.5% fall in FEV1 and -0.1% fall in V40p; p greater than 0.2), the changes being significantly different between the two periods (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)