IL-17 Aggravates Pseudomonas aeruginosa Airway Infection in Acute Exacerbations of Chronic Obstructive Pulmonary Disease.

airway infection increases risks of exacerbations and mortality in chronic obstructive pulmonary disease (COPD). We aimed to elucidate the role of IL-17 in the pathogenesis. We examined the expression and influences of IL-23/IL-17A in patients with stable COPD ( = 33) or acute COPD exacerbations with infection ( = 34). A mouse model of COPD (C57BL/6) was used to investigate the role of IL-17A in host inflammatory responses against infection through the application of IL-17A-neutralizing antibody or recombinant IL-17A. We found that infection increased IL-23/17A signaling in lungs of both COPD patients and COPD mouse models. When COPD mouse models were treated with neutralizing antibody targeting IL-17A, induced a significantly less polymorphonuclear leukocyte infiltration and less bacterial burden in their lungs compared to those of untreated counterparts. The lung function was also improved by neutralizing antibody. Furthermore, IL-17A-signaling blockade significantly reduced the expression of pro-inflammatory cytokine IL-1β, IL-18, TNF-α, CXCL1, CXCL15 and MMP-9, and increased the expression of anti-inflammatory cytokine IL-10 and IL-1Ra. The application of mouse recombinant IL-17A exacerbated -mediated inflammatory responses and pulmonary dysfunction in COPD mouse models. A cytokine protein array revealed that the expression of retinol binding protein 4 (RBP4) was down-regulated by IL-17A, and exogenous RBP4-recombinant protein resulted in a decrease in the severity of induced airway dysfunction. Concurrent application of IL-17A-neutralizing antibody and ciprofloxacin attenuated airway inflammation and ventilation after inoculation of in COPD mouse models. Our results revealed that IL-17 plays a detrimental role in the pathogenesis of airway infection during acute exacerbations of COPD. Targeting IL-17A is a potential therapeutic strategy in controlling the outcomes of infection in COPD patients.