Impact of former smoking exposure on airway eosinophilic activation and autoimmunity in patients with severe asthma

Severe eosinophilic asthma is characterised by frequent exacerbations and a relative insensitivity to steroids., Experimentally, smoking may induce eosinophilic airway inflammation, but the impact in patients with severe asthma is not clear. To investigate the association between smoking exposure in patients with severe asthma, and eosinophilic inflammation and activation, as well as airway autoimmunity and steroid responsiveness. Patients with severe asthma according to ERS/ATS criteria were assessed with sputum samples, analysed by cell differential count, and for the presence of free eosinophil granules (FEGs), autoantibodies against eosinophil peroxidase (EPX) and macrophage receptor with collagenous structure (MARCO). A subgroup of patients with eosinophilic airway inflammation was re-assessed after a 2-weeks course of prednisolone. A total of 132 severe asthmatics were included in the study; 39 patients (29.5%) had ≥10 pack years of smoking history; 36 (27.3%) were former smokers and 3 (2.3%) current smokers, and 93 (70.5%) had