title: IL-18 in induced sputum and airway hyperresponsiveness in mild asthmatics: effect of smoking.
abstract: Interleukin 18 (IL-18) is a pro-inflammatory cytokine, which has been shown to be implicated in the induction of airway hyperresponsiveness (AHR) in murine asthma models. The association of IL-18 with AHR in human bronchial asthma is not clear as yet. As cigarette smoking modifies airway inflammation we aimed to assess the relationship of IL-18 with airway hyperresponsiveness (AHR) in non-smoking versus smoking asthmatics. IL-18 was measured in sputum supernatants obtained from asthmatic (24 smokers and 22 non-smokers) and healthy subjects (16 smokers and 17 non-smokers). All subjects were assessed by spirometry, skin-prick tests to common aeroallergens and bronchial provocation to methacholine (Mch). There was no significant difference in IL-18 levels between healthy and asthmatic smokers and between healthy and asthmatic non-smokers. IL-18 levels in sputum were significantly lower in healthy smokers compared to non-smokers (p=0.048); similarly, in asthmatic smokers as compared to non-smokers (p=0.037). An inverse correlation was found between IL-18 levels, FEV(1) (% pred) (r=-0.495, p=0.043), and PD(20)Mc(h) in non-smoking asthmatics (r=-0.621, p=0.024). A positive correlation was found in smoking asthmatics between IL-18 levels in sputum and FEV(1) (% pred) (r=0.627, p=0.002), FVC (% pred) (r=0.460, p=0.031), and PD(20)Mc(h) (r=0.809, p=0.005). Cigarette smoking reduced IL-18 levels in induced sputum in healthy and asthmatic smokers. IL-18 levels were correlated with airway obstruction and AHR in an inverse way in smoking and non-smoking asthmatics. These results suggest the implication of IL-18 in airway hyperresponsiveness characterizing bronchial asthma, which is modified by smoking.
authors.affiliation: Sotiria Hospital for Diseases of the Chest, Department of Respiratory Medicine, University of Athens, Medical School, Athens, Greece. nikrovina@med.uoa.gr
authors.forename: Nikoletta
authors.initials: N
authors.lastname: Rovina
authors.forename: Efrossini
authors.initials: E
authors.lastname: Dima
authors.forename: Christina
authors.initials: C
authors.lastname: Gerassimou
authors.forename: Androniki
authors.initials: A
authors.lastname: Kollintza
authors.forename: Christina
authors.initials: C
authors.lastname: Gratziou
authors.forename: Charis
authors.initials: C
authors.lastname: Roussos
mesh_terms: D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D015415:Biomarkers / Q000032:analysis; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D016085:Bronchoconstrictor Agents; D002452:Cell Count; D006801:Humans; D020382:Interleukin-18 / Q000032:analysis*; D016210:Methacholine Chloride; D008875:Middle Aged; D012129:Respiratory Function Tests; D012907:Smoking / Q000009:adverse effects / Q000503:physiopathology*; D013183:Sputum / Q000737:chemistry / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D016085:Bronchoconstrictor Agents; D020382:Interleukin-18; D016210:Methacholine Chloride