Airway inflammation and bronchial bacterial colonization in chronic obstructive pulmonary disease.
BACKGROUND
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 > or = 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.
Division of Pulmonary/Critical Care and Sleep Medicine, and Division of Infectious Diseases, Department of Medicine, University at Buffalo, Buffalo, NY, USA. ssethi@buffalo.edu
Sanjay
S
Sethi
Jane
J
Maloney
Lori
L
Grove
Catherine
C
Wrona
Charles S
CS
Berenson
D000367:Age Factors; D000368:Aged; D001980:Bronchi / Q000378:metabolism* / Q000382:microbiology* / Q000473:pathology; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000382:microbiology; D001999:Bronchoscopy; D016022:Case-Control Studies; D015169:Colony Count, Microbial; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000382:microbiology* / Q000473:pathology; D012129:Respiratory Function Tests; D012907:Smoking
D016207:Cytokines; D018836:Inflammation Mediators