Imbalances of Th17 and Treg cells and their respective cytokines in COPD patients by disease stage.

The typical balance between Th17 and Treg T cell subsets is altered in various autoimmune diseases. Here, inflammatory markers in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) (n=32) and stable COPD (n=36) were compared with smokers with normal lung function (n=40, control group). Flow cytometry was used to detect proportions of Th17 and Treg cells in the peripheral blood. ELISA of induced sputum samples was used to detect IL-17 (secreted by Th17 cells) and TGF-β1 (secreted by Treg cells) concentrations. The proportion of Th17 cells in peripheral blood and secreted IL-17 and TGF-β1 levels in sputum were significantly higher in acute exacerbation of COPD patients than in stable COPD and control groups (P < 0.05). Additionally, the proportion of Treg cells was lower than in stable COPD but higher than in controls. Th17 proportions were negatively correlated with Treg proportions in both acute exacerbation and stable COPD patients, and positively correlated with IL-17 levels (P < 0.05). Further, there was a positive correlation between Treg proportion and TGF-β1 levels (P < 0.05). Thus, COPD patients have shifts in the balance of Th17/Treg cells. Acute exacerbation of COPD is shifted toward a pro-inflammatory response, while stable COPD is shifted toward an anti-inflammatory response. This finding may provide a new direction for future clinical treatment of COPD by seeking to repair the disrupted balance in T cells.