Is the neutrophil a worthy target in severe asthma and chronic obstructive pulmonary disease?

Both asthma and chronic obstructive pulmonary disease (COPD) are recognized as chronic inflammatory airway diseases. Over the past 20 years, considerable effort has gone into elucidating the complex cell and mediator interactions taking place in airways of patients with these diseases. Traditionally, asthma has been viewed as an eosinophilic disease, while neutrophils, together with macrophages, have been seen as being key inflammatory cells in COPD [1]. However, recent studies have blurred this rather simple distinction, with studies showing that a proportion of asthmatics, predominantly with severe asthma, have raised neutrophils in their airway lumen [2] and, interestingly, in their bronchial wall [3, 4]. Similarly, studies in COPD show that the numbers of airway eosinophil may increase in stable patients with sign of mast cell activation [5] and during exacerbations [6]. In a recent issue of Clinical and Experimental Allergy, Beeh and Beier provide a comprehensive review of the role of neutrophils in severe asthma and COPD and discuss potential targets of anti-neutrophil treatment [7]. This editorial discusses further the role of neutrophils in severe asthma and COPD and the critical importance of choosing the right outcomes when assessing the efficacy of new anti-inflammatory drugs in severe asthma and COPD.