The Significance of Serum Interleukin-8 in Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is closely related to disease mortality. Systemic inflammation is considered to be involved in the pathogenesis of AECOPD. The current study aimed to investigate the clinical significance of the classic chemokine interleukin (IL)-8 in serum during AECOPD. In this current cross sectional, observational study, 50 patients with AECOPD, 25 patients with stable COPD and 25 healthy nonsmokers as the control group were selected. Clinical characteristics and spirometry data were collected. All patients were classified as grade 1-4 based on forced expiratory volume in 1 second (FEV1) after bronchodilation according to the GOLD severity classification and were divided into frequent exacerbation (FE) group (≥2 times/year) and non-frequent exacerbation (NFE) group (<1 time/year) according to acute exacerbation (AE) times in the previous 12 months before the visit. The serum IL-8, IL-6, tumor necrosis factor (TNF)-α, and superoxide dismutase levels were measured by the enzyme-linked immunosorbent assay technique. Serum IL-8 levels increased sequentially from controls [9.45 pg/mL (ranged: 6.85-38.4)], to stable [51.60 pg/mL (ranged: 22.4-131.1)], and exacerbation stage [129 pg/mL (ranged: 57.7-374)]. The level of serum IL-8 was significant higher in patients with FE than that of patients with NFE (209.0 pg/mL (ranged: 115-472) vs 65.6 pg/mL (ranged: 11.2-149.3), P=0.008). A receiver operating characteristics curve (ROC) generated to evaluate IL-8, IL-6, and TNF-α levels to discriminate between patients with and without exacerbation showed that the total area under the curve (AUC) was 0.71 (95% confidence interval (CI): 0.5764-0.8381; P=0.003), 0.54 (95%CI: 0.4048-0.6943; P=0.54), and 0.52 (95%CI: 0.3912-0.6656; P= 0.7). Serum IL-8 is a sensitive, easy-to-measure, and inexpensive biomarker to give an indication of the course of COPD during exacerbation, and is a target to be explored further as a predictor to distinguish the patients prone to exacerbation