Interleukin-18 in induced sputum: Association with lung function in chronic obstructive pulmonary disease
Received 23 November 2008; accepted 14 January 2009. published online 09 February 2009.
Summary
Background
It has been shown that interleukin (IL)-18 levels in induced sputum are reduced in asthmatic and healthy smokers. However, in chronic obstructive pulmonary disease (COPD) patients, recent data show an overproduction in the lungs and increased serum levels of IL-18, suggesting that IL-18 may be involved in the pathogenesis of COPD.
Method
In order to assess the relation of IL-18 with pulmonary function and airway inflammation in COPD, IL-18, tumour necrosis factor-α, and IL-8 levels were measured by ELISA in sputum supernatants obtained from patients with bronchitis type COPD (n=28), and healthy subjects (18 smokers and 17 non-smokers). Cellular localization of IL-18 was assessed by immunocytochemistry.
Results
The levels of IL-18 were significantly higher in sputum supernatants of COPD patients compared to healthy smokers and non-smokers (p<0.05). IL-18 production was localized to sputum macrophages. IL-18 levels were inversely correlated with FEV1 (% predicted) (r=−0.572, p=0.002) and FEV1/FVC ratio in COPD smokers (r=−0.608, p=0.001). No correlations were found between IL-18 levels and inflammatory markers studied in induced sputum obtained from COPD patients, healthy smokers and non-smokers.
Conclusion
In patients with COPD, increased levels of IL-18 in induced sputum were associated with airflow limitation, suggesting that IL-18 may be implicated in the pathogenesis of COPD.
aDepartment of Respiratory Medicine, Medical School, University of Athens, “Sotiria” Hospital for Diseases of the Chest, 152 Mesogion Avenue, Athens GR-11527, Greece
b“M. Simos” Laboratories, Department of Critical Care and Pulmonary Services, Evangelismos Hospital, University of Athens, Athens, Greece
cAsthma and Allergy Centre, Pulmonary and Critical Care Department, Evgenidion Hospital, Medical School, University of Athens, Athens, Greece
ABSTRACT