Disruption of Th17/Treg Balance in the Sputum of Patients With Chronic Obstructive Pulmonary Disease

Abstract

BackgroundAmplified inflammation persists in the airways of patients with chronic obstructive pulmonary disease (COPD); however, the underlying mechanism is still unclear. Th17/T regulatory cells (Treg) imbalance may exist in the airways and contribute to this abnormal inflammation. MethodsThis study involved 21 patients with COPD, 21 healthy smokers (HS), and 21 healthy nonsmokers (HNS). We investigated receptor-related orphan receptor (RORC2) and fork-head box P3 (FOXP3) mRNA expression in induced sputum by realtime polymerase chain reaction and assayed IL-17, IL-10, TGF-β and IL-6 by enzyme-linked immunosorbent assay. Th17 and Treg cells in peripheral blood were analyzed by flow cytometry. ResultsThe level of sputum FOXP3 mRNA in both COPD and HNS was lower than that in HS (PCopd=0.017; PHNS=0.009). In contrast, the level of RORC2 mRNA was markedly higher in COPD than in either HS or HNS (PHS=0.005; PHNS<0.001). There was a correspondingly elevated ratio of sputum RORC2 to FOXP3 mRNA in COPD. Concentrations of IL-17, TGF-β and IL-6 were elevated in COPD sputum. In peripheral blood, both Th17 and Treg cells were elevated in COPD. ConclusionsA compartmental imbalance of Th17 over Treg exists in the airways of patients with COPD, suggesting a defect in antiinflammatory homeostasis in COPD.