Journal
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
Volume 173, Issue 9, Pages 991-998Publisher
AMER THORACIC SOC
DOI: 10.1164/rccm.200509-1525OC
Keywords
bacterial colonization; chronic obstructive pulmonary disease; neutrophilic inflammation
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Funding
- NHLBI NIH HHS [R01 HL066549] Funding Source: Medline
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Rationale: Inflammation is now recognized as an integral part of the pathogenesis of chronic obstructive pulmonary disease (COPD). In contrast to the sterile airways of normal lungs, bacterial pathogens are often isolated from the airways in stable COPD. This colonization of the tracheobronchial tree, currently believed to be innocuous, could serve as an inflammatory stimulus, independent of current tobacco smoke exposure. Objective: To test the hypothesis that bacterial colonization is associated with airway inflammation in stable COPD. Methods: Bronchoscopy with bronchoalveolar lavage (BAL) was performed in three groups of subjects: 26 ex-smokers with stable COPD (COPD), 20 ex-smokers without COPD (ex-smokers), and 15 healthy nonsmokers (nonsmokers). Quantitative bacterial cultures, cell counts, chemokine, cytokine, proteinase/antiproteinase, and endotoxin levels in the BAL fluid were compared. Results: Potentially pathogenic bacteria were recovered at >= 100 cfu/ml in 34.6% of COPD, 0% of ex-smokers, and in 6.7% of nonsmokers (p = 0.003). All values are expressed as median (interquartile range). Subjects with colonized COPD had significantly greater relative (12.0 [28.4] vs. 3.0 [7.8]%, p = 0.03) and absolute (4.98 [5.26] x 10(4)/ml vs. 3.04 [2.82] x 10(4)/ml, p = 0.02) neutrophil counts, interleukin 8 (33.8 [189.8] vs. 16.9 [20.1] pg/ml, p = 0.005), active matrix metalloproteinase-9 (2.16 [4.30] vs. 0.84 [0.99] U/ml, p = 0.03), and endotoxin (36.0 [72.6] vs. 3.55 [7.17] mEU/ml, p = 0.004) levels in the BAL than the subjects with noncolonized COPD. These inflammatory constituents of BAL were also significantly elevated in subjects with colonized COPD when compared with ex-smokers and nonsmokers. Conclusions: Bacterial colonization is associated with neutrophilic airway lumen inflammation in ex-smokers with COPD and could contribute to progression of airway disease in COPD.
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