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Exhaled nitric oxide: A biomarker integrating both lung function and airway inflammation changes

par Haccuria, Amaryllis ;Michils, Alain ;Michiels, Stefan ;Van Muylem, Alain
Référence Journal of allergy and clinical immunology, 134, 3, page (554-559)
Publication Publié, 2014

Article révisé par les pairs

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Résumé :

Background The increased fraction of exhaled nitric oxide (Feno) values observed in asthmatic patients are thought to reflect increased airway inflammation. However, Feno values can be affected by airway caliber reduction, representing a bias when using Feno values to assess asthma control. Objective We sought to determine the effect of changes in both airway caliber and inflammation on Feno values using the allergen challenge model. Methods FEV 1 and Feno values were measured during early airway responses (EARs) and late airway responses after challenge with house dust mite allergens in 15 patients with mild allergic asthma. Helium and sulfur hexafluoride (SF 6) phase III expired concentration slopes (SHe and S SF6, respectively) from single-breath washout tests were measured to identify sites of airway constriction. Results In EARs, FEV1 and Feno value decreases reached 36.8% and 22%, respectively (P <.001). ΔS He was greater than ΔSSF6 (+189.4% vs +82.2%, P =.001). In late airway responses FEV1 and Feno value decreases reached 31.7% and 28.7%, respectively (P <.001), with the same ΔS He and ΔSSF6 pattern (+155.8% vs +76%, P =.001). Eight hours after the EAR, FEV1 was still decreased (P <.001), whereas Feno values had returned to baseline. At 24 hours, FEV1 had returned to baseline, with Feno values increased by 38.7% (P =.04). Conclusion In patients with mild allergic asthma, airway caliber changes modulate changes in Feno values resulting from airway inflammation. Therefore Feno should no longer be considered solely an inflammation biomarker but rather a biomarker that integrates both airway inflammation and lung function changes. Furthermore, early and late phases resulting from allergen exposure were shown to involve similar lung regions. © 2014 The Authors. Published by Elsevier Inc.