Airway inflammation assessed by invasive and noninvasive means in severe asthma: eosinophilic and noneosinophilic phenotypes.
BACKGROUND
Airway inflammation assessed by bronchial biopsies demonstrates distinct eosinophilic and noneosinophilic phenotypes in severe asthma, but their relationship to other biomarkers of disease (induced sputum and nitric oxide [NO]) is not clear.


OBJECTIVE
We sought to compare airway inflammation using noninvasive (induced sputum, exhaled NO), and invasive (bronchial biopsies) methods in moderate and severe asthma and to assess whether induced sputum and exhaled NO would allow the identification of eosinophilic and noneosinophilic phenotypes in severe asthma.


METHODS
We performed a cross-sectional study of 32 subjects with severe asthma and 35 subjects with moderate asthma, from whom we obtained bronchial biopsies, induced sputum, and exhaled NO measurements.


RESULTS
Among subjects with severe asthma, we identified eosinophilic and noneosinophilic phenotypes using both bronchial biopsies and sputum cell counts. However, the vast majority of subjects with high sputum eosinophil counts did not have high mucosal eosinophil counts. Exhaled NO was increased in the eosinophilic phenotype as judged from bronchial biopsy findings, but not on the basis of induced sputum. Subjects with high sputum eosinophil counts experienced more asthma exacerbations than the subjects with low sputum eosinophil counts. In contrast, we did not find any differences in the clinical characteristics between eosinophilic and noneosinophilic phenotypes that were identified by bronchial biopsies.


CONCLUSIONS
The use of sputum cell counts allowed the identification of a subgroup of subjects with severe asthma who were at risk of more frequent asthma exacerbations.


CONCLUSIONS
Monitoring sputum eosinophil counts in subjects with severe asthma may allow identifying the subjects with the greatest disease activity.
Lemière
Catherine
C
Hôpital du Sacré-Coeur de Montréal, University of Montreal, Montreal, Quebec, Canada. catherine.lemiere@umontreal.ca <catherine.lemiere@umontreal.ca>
Ernst
Pierre
P
Olivenstein
Ron
R
Yamauchi
Yasuhiro
Y
Govindaraju
Karuthapillai
K
Ludwig
Mara S
MS
Martin
James G
JG
Hamid
Qutayba
Q
D001249:Asthma / Q000145:classification / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D001706:Biopsy; D001980:Bronchi / Q000473:pathology; D003430:Cross-Sectional Studies; D004804:Eosinophils / Q000276:immunology / Q000473:pathology*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000145:classification / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D010641:Phenotype; D012720:Severity of Illness Index; D013183:Sputum / Q000276:immunology
D009569:Nitric Oxide