Correlation between Th17/Treg ratio imbalance and impaired lung function in patients with COPD
Objective To study the correlation between immune imbalance mediated by Th 17 and Treg cells and impaired lung function in patients with chronic obstructive pulmonary disease （ COPD ） . Methods Ninety-five patients with moderate or severe COPD , thirty-five smokers with normal lung function and thirty-one healthy non-smokers from Yinzhou People′s Hospital from January 2009 to December 2012 were recruited in this study .The percentages of circulating Th 17 and Treg cells in peripheral blood samples were determined by flow cytometry .The concentrations of cytokines in serum samples and supernatants of in-duced sputum samples were measured by enzyme-linked immunosorbent assay （ELISA）.The expression of ROR-γt and Foxp3 at mRNA level in peripheral blood mononuclear cells （ PBMC） were determined by quan-titative real-time PCR.The potential association between ratios of Th 17/Treg cells and lung function was evaluated.Results Compared with smokers and healthy subjects , patients with moderate or severe COPD showed high levels of Th17 cells, IL-17A, IL-6 and IL-23, and an up-regulated expression of ROR-γt at transcriptional level .However, the percentage of Treg cells , IL-10 level and the expression of Foxp 3 at mRNA level were down-regulated in patients with COPD .The levels of cytokines in supernatants of induced sputum samples varied in the same way as that of Th 17/Treg in peripheral blood samples .The ratio of Th17 to Treg cells was negatively correlated with the values of forced vital capacity （ FVC） , forced expiratory vol-ume in one second （FEV1）, and FEV1/FVC.Conclusion Th17/Treg cells imbalance was closely associ-ated with the deterioration of pulmonary function in patients with moderate or severe COPD .Th17/Treg cells imbalance might be involved in the progression of COPD . 
 
Key words: 
Chronic obstructive pulmonary disease; Th17 cells; Regulatory T cells; Lung func-tion; Immune imbalance