Inflammatory response in acute viral exacerbations of COPD

Background: Respiratory viruses are important triggers of acute exacerbations of COPD (AE-COPD). However, the inflammatory response in virus-positive exacerbations is still not fully understood. Methods: We investigated CRP, IL-6, IL-8, IL-10, IFN-gamma, blood and sputum cells in patients with acute exacerbation (n = 36) and in stable disease (n = 20) and correlated these parameters to virus detection in respiratory secretions. Results: Similar to other studies we found a significant increase in systemic CRP and absolute numbers of blood Leukocytes in AE-COPD patients. Sputum IL-6 levels and sputum eosinophils tended to be higher during exacerbation. In patients with detection of respiratory viruses in nasal lavage, local IL-6 production in sputum was significantly increased; FEV1 was significantly decreased and both parameters were inversely correlated to each other. Conclusion: This study supports previous findings of both, increased local and systemic inflammation in acute exacerbation of COPD. In virus-associated exacerbations, IL-6 is significantly increased and negatively correlated to FEV1 indicating a relation between virus-induced inflammation and airway obstruction. However, regarding our finding and previous data, it is becoming increasingly clear that the mediators investigated so far do not permit identifying the etiology of AE-COPD. Hence, further studies are needed to better define the inflammatory response in AE-COPD in general and in viral exacerbations in particular.