Association between airway inflammation and systemic inflammation in stable chronic obstructive pulmonary disease

Objective The aim of this prospective study was to investigate the association between airway inflammation and systemic inflammation in stable patients with chronic obstructive pulmonary disease (COPD). Methods A total of 35 stable patients with COPD were enrolled in this study. Induced sputum and blood samples were obtained from all of the patients for sputum quantitative bacterial cultures,sputum cell counts,analysed the plasma levels of fibrinogen (Fbg) and the serum levels of high sensitivity C- reactive protein (CRP). Results ①There were 19 COPD patients with lower airway bacterial colonization (LABC). Patients with LABC had significantly greater relative neutrophil counts number in the sputum than those without LABC ( P =0. 008). Similarly,the number of lymphocyte in the sputum was correlated with LABC ( P =0. 011). ②The serum levels of CRP and the plasma levels of Fbg were measured. Subjects with colonized COPD had not significantly greater absolute CRP levels in the serum and Fbg levels in the plasma than the subjects with noncolonized COPD ( P ＞0. 05). ③There were no significant relationship between the number of LABC and the levels of CRP in the serum ( P ＞0. 05) , or between the number of LABC and the levels of Fbg in the plasma ( P ＞0. 05).④There was no significant relationship between the number of neutrophil or lymphocyte in the sputum,and the levels of CRP in the serum or Fbg in the plasma ( P ＞0. 05). ⑤There was no significant relationship between CRP and FEV1 % predicted (FEV1 % pred) ( r = -0. 230, P =0. 292),while there was a negative association between Fbg and FEV1 % pred ( r = - 0. 571, P = 0.014). Conclusions LABC,which is one of the most important origins of airway inflammation in COPD, was 54. 29% in stable patients with COPD. Airway inflammation may not be the cause which leads to systemic inflammation. However,this conclusion needs to be confirmed by further studies because of small subjects in this study. Systemic inflammation is related with lung function impairment. Key words: Chronic obstructive pulmonary disease;  Lower airway bacterial colonization;  Airway inflammation ;  Systemic inflammation