Pulmonary infection is associated with an increased IL-6 in acute exacerbation chronic obstructive pulmonary disease

Acute Exacerbation Chronic Obstructive Pulmonary Disease (AECOPD) is associated with an acute worsening of respiratory symptoms that have effects on lung function, quality of life and health economic burden. In addition, the development of pulmonary infections is a common complication of Chronic Obstructive Pulmonary Disease (COPD). In the pathophysiology of AECOPD, interleukin (IL)-6 is a pleiotropic cytokine that can be produced by inflammatory and primary lung epithelial cells in response to a variety of different stimuli. We aim to investigate the correlation between serum cytokine levels and AECOPD with pulmonary infection. 37 AECOPD patients diagnosed with pulmonary infection and 33 patients diagnosed with AECOPD only were selected. All COPD patients were diagnosed according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Serum samples for C-reactive protein (CRP) and cytokines were obtained from the patients immediately after admission. Serum concentrations of cytokines were measured using a fluorescent bead immunoassay on a flow cytometer. Logistic regression was used to identify risk factors for AECOPD co-infection of the lungs. Serum characterization of our cohort showed patients with AECOPD and pulmonary infection had higher levels of IL-6 and IL-10 compared with the AECOPD group, and IL-6 was independently associated with AECOPD with pulmonary infection. ROC curve analysis showed that IL-6 was a useful predictor of the incidence of pulmonary infection in AECOPD patients. Our findings highlight the role of IL-6 in the pathogenesis of AECOPD with pulmonary infection.