Downregulation of regulatory T cells in patients with chronic obstructive pulmonary disease: relation to disease severity

Bachground Chronic obstructive pulmonary disease (COPD) is a slowly progressing disease that has the characteristics of chronic inflammation of the airways and destruction of lung parenchyma; the pathogenesis of which is partially understood. COPD might have an autoimmune pathogenesis. It has been documented that disturbance of CD4(+) T-regulatory (Treg) lymphocytes leads to breakdown of self-tolerance and development of many diseases. Limited data are available about the role of Treg cells in COPD. Objective To determine the role of Treg cells in the pathogenesis and severity of COPD. Patients and methods This prospective case-control study was conducted on 34 patients with COPD and 48 healthy controls (24 smokers and 24 never-smokers). Flow cytometry analysis for Treg cells was used. Results CD4(+)CD25(high) cells percentage and cytoplasmic forkhead box protein P3 expression were significantly lower in COPD compared with healthy controls, either nonsmokers or smokers (P<0.05). Accordingly, both the percentage of cytoplasmic forkhead box protein P3 expression and its mean fluorescent intensity were significantly lower in patients with COPD compared with the nonsmokers and smokers (P=0.011, 0.002 and 0.002, respectively). A significant positive correlation between CD4(+)CD25(high) percentage and either forced expiratory volume in one second percentage predicted and forced expiratory volume in one second/forced vital capacity ratio was detected (r=691, P<0.001; r=729, P<0.001). Conclusion There is downregulation of Treg cells in COPD, and this could play a role in the pathogenesis of COPD.