%0 Journal Article %A Nikoletta Rovina %A Efrossini Dima %A Georgia Papadaki %A Theocharis Anagnostakos %A Charis Roussos %A Manos Alchanatis %A Nikolaos Koulouris %T IL-18 in infectious exacerbations of COPD %D 2011 %J European Respiratory Journal %P p471 %V 38 %N Suppl 55 %X The nnate immune system is critical in recognizing bacterial and viral infections to evoke a proper immune response. IL-18, a pro-inflammatory and pro-apoptotic cytokine with crucial role in host defense against bacterial invasion is increased in lungs, serum and sputum of COPD patients, suggesting that IL-18 may be involved in chronic inflammation of COPD. We aimed to investigate the effect of infectious acute exacerbations of COPD (AECOPD) on IL-18 levels.We examined 40 patients with COPD hospitalized for infectious AECOPD according to Anthonisen's criteria and 20 patients with stable COPD. We examined sputum for inflammation and for bacterial infection using PCR. IL-18 was measured in induced sputum and serum at baseline and after treatment of the exacerbation. Immunocytochemistry of IL-18 expression in sputum cells was performed using a mouse monoclonal IL-18 antibody.All patients had no previous hospitalization the preceding 3 months and none was diagnosed with pneumonia.IL-18 levels in sputum were found significantly lower in AECOPD compared to stable state (p=0.05), while right after treatment IL-18 levels were increased compared to the stable state levels (p>0.05). Positive staining of IL-18 was observed in macrophages in immunocytochemistry. An inverse correlation was found between IL-18 levels and sputum macrophages in AECOPD (r=-630, p=0.028). Serum IL-18 levels were elevated in exacerbations (p>0.05) compared to stable state, and decreased after treatment to stable disease levels (p>0.05).Our data show that although IL-18 is involved in host defence against bacterial pathogens in infectious AECOPD there may be a dysregulated activation of airways' macrophages and perhaps inflammasome mediated pathways. %U