Imbalance of peripheral blood Th17 and Treg responses in patients with chronic obstructive pulmonary disease.

BACKGROUND: Autoimmune responses mediated by cluster of differentiation 4(+) T cells may contribute to the development of chronic obstructive pulmonary disease (COPD). However, little is known about the frequency of peripheral blood Th17 cells and of regulatory T cells (Tregs) in Chinese patients with COPD. This study is aimed at determining the frequency of circulating Th17 and Tregs in patients with moderate and severe COPD, heavy smokers and healthy controls (HC).

METHOD: The percentages of circulating T-helper type (Th)17 cells and Tregs were determined by flow cytometry in 32 patients with moderate COPD, 33 patients with severe COPD, 35 smokers, and 31 HC. The concentrations of serum Th17- and Treg-related cytokines were measured by enzyme-linked immunosorbent assay (ELISA). The levels of retinoic acid orphan receptor (ROR)-γt and Forkhead box p3 (Foxp3) mRNA transcripts in peripheral blood mononuclear cells were determined by real-time polymerase chain reaction. The potential correlation between the percentages of Th17 Tregs, serum cytokines and lung function was evaluated.

RESULTS: In comparison with that in the smokers and HC, significantly higher frequencies of Th17 cells and higher levels of ROR-γt mRNA transcripts and serum interleukin (IL)-17A, IL-6, IL-21, IL-22 and IL-23, but lower frequency of Tregs and lower levels of Foxp3 and serum IL-10 were detected in patients with moderate and severe COPD. The increased ratios of Th17 to Tregs were negatively correlated with the values of forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and FEV1/FVC.

CONCLUSIONS: An imbalance of circulating Th17 cells and Tregs is associated with the deterioration of pulmonary function in patients with moderate and severe COPD.