IL-17A and the Promotion of Neutrophilia in Acute Exacerbation of Chronic Obstructive Pulmonary Disease.

Rationale: Nontypeable Haemophilus influenzae (NTHi) causes acute exacerbation of chronic obstructive pulmonary disease (AECOPD). IL-17A is central for neutrophilic inflammation and has been linked to COPD pathogenesis.Objectives: We investigated whether IL-17A is elevated in NTHi-associated AECOPD and required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke.Methods: Experimental studies with cigarette smoke and NTHi infection were pursued in gene-targeted mice and using antibody intervention. IL-17A was measured in sputum collected from patients with COPD at baseline, during, and after AECOPD.Measurements and Main Results: Exacerbated airway neutrophilia in cigarette smoke–exposed mice infected with NTHi was associated with an induction of IL-17A. In agreement, elevated IL-17A was observed in sputum collected during NTHi-associated AECOPD, compared with samples collected before or after the event. NTHi-exacerbated neutrophilia and induction of neutrophil chemoattractants over the b...