RT Journal Article
SR Electronic
T1 Assessment of airway neutrophil activation in adult non-eosinophilic asthma
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP p3261
VO 38
IS Suppl 55
A1 Collin Brooks
A1 Christine van Dalen
A1 Elizabeth Harding
A1 Ian Hermans
A1 Jeroen Douwes
YR 2011
UL http://erj.ersjournals.com/content/38/Suppl_55/p3261.abstract
AB Background: It is now evident that there are different pathophysiologies underlying different asthma phenotypes. The neutrophil has been proposed to be a principal cell type involved in non-eosinophilic asthma (NEA).Aims: To investigate different aspects of neutrophil activation in NEA.Methods: 24 adult asthmatics (9 eosinophilic asthma (EA>2% sputum eosinophils), 15 NEA) and 18 healthy controls were recruited by advertisement and successfully underwent clinical assessment, spirometry and sputum induction. Sputum was analysed for neutrophil number (differential cell count), levels of neutrophil-associated soluble mediators (myeloperoxidase (MPO), IL-8 and MMP-9, by ELISA) and neutrophil expression of CD11b (flow cytometry).Results: Only one asthmatic individual in our study was neutrophilic (>61% neutrophils). EA was generally associated with a more severe clinical phenotype and poorer control (40% poorly controlled) than NEA (8%). There was no statistically significant difference in percentage of sputum neutrophils, neutrophil expression of CD11b, or sputum levels of MPO, IL-8 or MMP-9, between EA, NEA or control subjects. However, we observed that neutrophil percentage increased with age regardless of disease status (RS=0.71, p<0.0001), and this increase in neutrophils was associated with higher levels of IL-8 (RS=0.36, p=0.02), and MMP-9 (RS=0.55, p=0.0002).Conclusions: Our results show no difference in neutrophil activation in NEA compared to either EA or healthy controls. They also support previous data showing an increase in neutrophil number with aging in both asthma and healthy controls, and suggest that age must be appropriately controlled for when defining a neutrophilic asthma phenotype.