Abstract
Background: Airway muscle hypertrophy is a surrogate of airway remodeling and eosinophilia in induced sputum (IS) is associated to lack of asthma control.
Objective: Compare the amount of ASM in endobronchial biopsies with eosinophils %(Eos) in IS in severe asthmatics after optimal treatment.
Methods: 62 severe asthmatics received a 2-week prednisone trial and high inhaled corticosteroid dose (ICs) plus LABA for 12 weeks and were classified according to lung function after the 2-week oral corticosteroid trial. Persistent airflow obstruction (PAO) was defined by FEV1post BD <80% plus FEV1/FVC post BD ≤0.70. IS and bronchial biopsies were performed at the end of the 12 weeks. The fractional area of ASM, assessed by quantification of alpha-smooth muscle actin, and Eos% and neutrophils% (Neu) in IS were assessed.
Results: 48 patients were classified as PAO,14 as non persistent airflow obstruction (NPAO). The fractional area of ASM was higher in PAO (p=0,041), but Neu% and Eos% in IS was not different between groups. There was a strong inverse correlation between IS Eos and total area muscle actin (r = -0.83, p=0.001) in the NPAO and a positive correlation in the PAO group (r = 0.36, p = 0.038). No correlations were found with Neu.
Conclusion: Persistent obstructed severe asthmatics have more smooth muscle in airways. In patients that normalize lung function after optimal treatment, Eo inflammation is inversely associated with ASM mass in the biopsies, whereas the opposite occurs in persistent obstructed patients. These data suggest that structural alterations, in parallalel with inflammation, are related to functional abnormalities in the persistent obstructed patients.
- © 2012 ERS