Airway inflammation and anti-protease defences rapidly improve during treatment of an acute exacerbation of COPD

Background and objective: There are few data on the short-term natural history of airway inflammation during severe episodes of acute exacerbation of COPD (AECOPD). An observational study was performed to determine how rapidly conventional treatment improves airway inflammation in patients admitted to hospital with AECOPD. Methods: Twenty-four consecutive patients with AECOPD were recruited and changes in sputum inflammatory indices were assessed after 2 and 4 days of treatment. The primary end-points included presence of bacteria and viruses, changes in sputum total cell counts (TCC) and polymorphonuclear leukocyte (PMN) differential counts, and levels of secretory leukocyte protease inhibitor (SLPI), IL-8 and TNF-a. Results: All patients received oral corticosteroids and 17 (71%) were also treated with oral antibiotics. A bacterial or viral pathogen was isolated from 12 patients (50%), and Aspergillus fumigatus was isolated from one. A positive bacterial culture was associated with increased sputum TCC and PMN count (P < 0.05), as well as higher levels of IL-8 and TNF-a (P < 0.05), and a trend towards lower sputum SLPI levels (P = 0.06). Sputum PMN numbers fell by 70% within the first 48 h of admission (P < 0.05), accompanied by an increase in sputum SLPI (P < 0.001) and reductions in the levels of TNF-a (P < 0.005) and IL-8 (P = 0.06), with no further significant change at 4 days. Conclusions: Conventional treatment for severe AECOPD is associated with rapid reduction of neutrophilic inflammation and improvement in anti-protease defences.