Inflammatory biomarkers in airways of patients with severe asthma compared with non-severe asthma
Article first published online: 20 JUL 2009
© 2009 Blackwell Publishing Ltd
Clinical & Experimental Allergy
Volume 39, Issue 11, pages 1668–1676, November 2009
How to Cite
Macedo, P., Hew, M., Torrego, A., Jouneau, S., Oates, T., Durham, A. and Chung, K. F. (2009), Inflammatory biomarkers in airways of patients with severe asthma compared with non-severe asthma. Clinical & Experimental Allergy, 39: 1668–1676. doi: 10.1111/j.1365-2222.2009.03319.x
- Issue published online: 21 OCT 2009
- Article first published online: 20 JUL 2009
- Submitted 23 September 2008; revised 22 April 2009; accepted 29 May 2009*Corrected, details indicated after Acknowledgement
- airway smooth muscle;
- bronchial biopsies;
- severe asthma;
- subbasement membrane thickness
Background About 5–10% of patients with asthma suffer from poorly-controlled disease despite corticosteroid (CS) therapy.
Objective We determined whether there were any differences in inflammatory biomarkers between severe and non-severe asthma patients.
Methods Nineteen severe and 20 non-severe asthma patients were recruited and underwent collection of induced sputum, bronchoalveolar lavage (BAL) fluid and bronchial biopsies.
Results Biopsy results showed no differences in eosinophils (major basic protein positive), neutrophils, macrophages, T cells and mast cells in the bronchial submucosa. However, subbasement membrane (SBM) thickness and smooth muscle area were increased in the biopsies. No significant differences were observed in the induced sputum inflammatory cells. In BAL fluid, there was a significant increase in neutrophils but a significant decrease in macrophages. Eosinophil counts were non-significantly increased threefold in both sputum and BAL in severe asthma. Levels of IL-8 and IL-13 in sputum supernatants were similar in both groups of asthma patients. There was a significant inverse correlation between post-bronchodilator forced expiratory volume in 1 s and provocative concentration of methacholine causing a 20% fall in FEV1 with SBM thickness.
Conclusion Differences in inflammatory cells were observed mainly in terms of increased neutrophils and reduction in macrophage numbers in BAL fluid with a trend towards increased eosinophils in severe asthma compared with non-severe asthma. However, the most notable features are the increase in features of airway wall remodelling of SBM thickness and smooth muscle area.