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

Background: Amplified 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. Methods: This study involved 21 patients with COPD, 21 healthy smokers (HS), and 21 healthy nonsmokers (HNS). We investigated receptor-related orphan receptor (RORC2) and forkhead box P3 (FOXP3) mRNA expression in induced sputum by real-time polymerase chain reaction and assayed IL-17, IL-10, TGF-beta and IL-6 by enzyme-linked immunosorbent assay. Th17 and Treg cells in peripheral blood were analyzed by flow cytometry. Results: The level of sputum FOXP3 mRNA in both COPD and HNS was lower than that in HS (PCOPD = 0.017; P-HNS = 0.009). In contrast, the level of RORC2 mRNA was markedly higher in COPD than in either HS or HNS (P-HS = 0.005; P-HNS < 0.001). There was a correspondingly elevated ratio of sputum RORC2 to FOXP3 mRNA in COPD. Concentrations of IL-17, TGF-beta and IL-6 were elevated in COPD sputum. In peripheral blood, both Th17 and Treg cells were elevated in COPD. Conclusions: A compartmental imbalance of Th17 over Treg exists in the airways of patients with COPD, suggesting a defect in anti-inflammatory homeostasis in COPD.