Levels of inflammatory mediators in chronic obstructive pulmonary disease patients with anemia of chronic disease: a case-control study

Abstract

Although a subset of patients with chronic obstructive pulmonary disease (COPD) display anemia, the role of elevated pro-inflammatory cytokines in COPD-related anemia of chronic disease (ACD) has not been fully investigated. To examine the levels of interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor-alpha (TNFα), interferon-gamma (IFNγ), C-reactive protein (CRP) and erythropoietin in stable COPD outpatients with and without ACD. A case-control design was followed. Fifty-four patients with stable COPD were studied. Among them, 27 had ACD according to strict clinical and laboratory criteria (group of cases), while another 27 nonanemic COPD patients, carefully matched to cases for age, gender, height, lung function and smoking status represented the controls. Serum levels of IL-1β, IL-6, IL-10, TNFα, IFNγ, CRP and erythropoietin were measured in both groups. Patients with ACD had significantly higher levels of IL-10 [25.6 (1.9-95.2) vs. 4.1 (1.9-31.9) pg/ml, P = 0.049] and IFNγ [15.2 (2.2-106.9) vs. 2 (1.2-18.3) pg/ml, P = 0.026] and had more frequently elevated CRP than controls. Levels of IL-1β [26.2 (9.8-96.4) vs. 7.9 (2.1-28.4) pg/ml, P = 0.073], IL-6 [20.3 (2.1-125.4) vs. 6.2 (1.2-33.8) pg/ml, P = 0.688] and TNFα [30.1 (3.2-107.5) vs. 10.1 (3.2-50.4) pg/ml, P = 0.131] were also higher in cases, but the differences did not reach statistical significance. Patients with ACD also displayed significantly higher erythropoietin levels than controls [(21.9 (8.4-101.7) vs. 9.7 (6.3-21.7) mIU/ml, P = 0.010], indicating erythropoietin resistance. This study shows that in stable COPD outpatients with strictly defined ACD, levels of inflammatory mediators and erythropoietin are elevated compared to nonanemic controls.