We investigated the immunoexpression of the Th17 related cytokines in the bronchial biopsies of patients with increasing COPD severity and observed significantly higher levels of epithelial IL-22 and submucosal IL-22 and IL-17 in patients with mild/moderate COPD compared with control nonsmokers, suggesting a role for these Th17 related cytokines in substaining tissutal neutrophilia in the bronchi of these patients [39]. This evidence concerns the gene IL17A and chronic obstructive pulmonary disease.