Elevated serum IL-8: a biomarker indicating exacerbation-prone COPD

Objective: Interleukin-8 (IL-8) was thought to be associated with all-cause mortality and exacerbation frequency of COPD. The underlying mechanism and concrete characteristics of patients with high level of serum IL-8 was not fully elucidated. The study was to compare the difference of clinical features between high and low level of serum IL-8. Methods: 112 COPD patients were enrolled and were followed up for one year prospectively. The systemic inflammatory markers were detected and clinical data were collected at time of enrollment. High level (>=62pg/ml, n=47) and low (<62pg/ml, n=65) level patients received adequate formal treatment by GOLD. Moderate-severe exacerbations were recorded during follow-up period. Results: Patients with high serum IL-8 level showed significant higher proportion with atopic physical condition, CAT scores and airway wall thickness compared with low level group. Absolute values and percentage of the predicted values of preFEF25-75% and preFEF75%, were lower significantly than low IL-8 group as well as DLCO. IL-8 level was correlated with DLCO negatively. Accumulated times of moderate-severe exacerbations in high level group was obviously more than that of lower group (11 vs 4) with HR 3.06 (95% CI 1.053 -8.927, P<0.05) in multivariate Cox regression analysis. Conclusions: COPD patients with serum IL-8 elevation suggest prone to exacerbation in the real-world clinic, which may be due to combined atopy, small airway function deterioration, decrease diffuse capacity and airway remodeling. These results indicate serum IL-8 level would be a useful and convenient biomarker to indicate the COPD patients with predisposed exacerbation.