Innate immune activation in neurtrophilic asthma

We would appreciate the opportunity to comment on the very interesting recently published paper by Simpson and colleagues, putatively describing innate immune activation in a neutrophilic variant " of asthma in inhaled corticosteroid (ICS) treated patients. We feel that the paper is especially important and effective in highlighting the heterogeneity of airway cellular infiltrates in asthma especially after exposure to corticosteroid. We endorse the proposal that neutrophils are involved pathogenically even in stable asthma. This is likely to be the case even when neutrophils are not grossly elevated in number and indeed they may be at least as relevant as eosinophils across the board as suggested in early bronchoscopic studies. In these published data neutrophil cellular activation and also macrophage activation were more marked than their absolute number suggested even in patients with relatively mild stable asthma."