Likewise, extracellular IL-26 levels in long-term smokers were further increased in the induced sputum in patients with exacerbations of COPD compared to steady-state patients, in BAL samples from patients with chronic bronchitis, and in the induced sputum and BW samples in subjects with chronic colonization by pathogenic bacteria [40]. This evidence concerns the gene IL26 and chronic obstructive pulmonary disease.