Airway inflammation and mannitol challenge test in COPD |
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Authors: | Selma B de Nijs Niki Fens Rene Lutter Erica Dijkers Frans H Krouwels Barbara S Smids-Dierdorp Reindert P van Steenwijk Peter J Sterk |
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Institution: | 1.Department of Respiratory Medicine, Academic Medical Centre and University of Amsterdam, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands;2.Department of Experimental Immunology, Academic Medical Centre and University of Amsterdam, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands;3.Department of Pulmonology, Onze Lieve Vrouwe hospital, Oosterpark 9, Amsterdam, 1091 AC, The Netherlands |
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Abstract: | BackgroundEosinophilic airway inflammation has successfully been used to tailor anti-inflammatory therapy in chronic obstructive pulmonary disease (COPD). Airway hyperresponsiveness (AHR) by indirect challenges is associated with airway inflammation. We hypothesized that AHR to inhaled mannitol captures eosinophilia in induced sputum in COPD.MethodsTwenty-eight patients (age 58 ± 7.8 yr, packyears 40 ± 15.5, post-bronchodilator FEV1 77 ± 14.0%predicted, no inhaled steroids ≥4 wks) with mild-moderate COPD (GOLD I-II) completed two randomized visits with hypertonic saline-induced sputum and mannitol challenge (including sputum collection). AHR to mannitol was expressed as response-dose-ratio (RDR) and related to cell counts, ECP, MPO and IL-8 levels in sputum.ResultsThere was a positive correlation between RDR to mannitol and eosinophil numbers (r = 0.47, p = 0.03) and level of IL-8 (r = 0.46, p = 0.04) in hypertonic saline-induced sputum. Furthermore, significant correlations were found between RDR and eosinophil numbers (r = 0.71, p = 0.001), level of ECP (r = 0.72, p = 0.001), IL-8 (r = 0.57, p = 0.015) and MPO (r = 0.64, p = 0.007) in sputum collected after mannitol challenge. ROC-curves showed 60% sensitivity and 100% specificity of RDR for >2.5% eosinophils in mannitol-induced sputum.ConclusionsIn mild-moderate COPD mannitol hyperresponsiveness is associated with biomarkers of airway inflammation. The high specificity of mannitol challenge suggests that the test is particularly suitable to exclude eosinophilic airways inflammation, which may facilitate individualized treatment in COPD.Trial registrationNetherlands Trial Register (NTR): NTR1283 |
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