Association between plasma interleukin-33 level and acute exacerbation of chronic obstructive pulmonary disease.

BACKGROUND: The role of interleukin (IL)-33 in patients with chronic obstructive pulmonary disease (COPD) has not been well elucidated. The aim of this study is to analyze the association between plasma IL-33 level and acute exacerbation of COPD. METHODS: Plasma IL-33 was measured in 62 COPD patients during their stable state. Patients were prospectively followed up for 1 year. The expression of IL-33 was measured in lung tissue obtained from 38 patients who underwent surgery. RESULTS: The number of exacerbations was significantly higher in the high plasma IL-33 group compared with the low plasma IL-33 group. On Poisson regression analysis, high plasma IL-33 was associated with increased risk of exacerbation (incidence rate ratio = 2.166, P = 0.043). The expression of IL-33 in the lung was higher in COPD patients than in controls. The expression of IL-33 was significantly correlated with smoking pack years (R = 0.45, P < 0.01) and Forced expiratory volume in 1 s (%) (R = - 0.58, P < 0.01). CONCLUSION: The plasma level of IL-33 in patients with COPD was significantly associated with the risk of exacerbation in prospective follow up. The expression of IL-33 in the lung was positively correlated with smoking and negatively correlated with lung function.