Relationship between airway colonization, inflammation and exacerbation frequency in COPD

Respir Med. 2007 Apr;101(4):729-37. doi: 10.1016/j.rmed.2006.08.020. Epub 2006 Sep 26.


Rationale: To evaluate bacterial colonization and the airway inflammatory response, and its relationship to the frequency of exacerbation in patients with stable chronic obstructive pulmonary disease (COPD).

Methods: Quantitative bacteriologic cultures, neutrophil elastase, myeloperoxidase (MPO), tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-8 were measured in bronchoalveoler lavage (BAL) in 39 patients with stable COPD [19 with frequent exacerbation (> or = 3/year), and 20 with infrequent] and in 18 healthy controls (10 smokers and 8 non-smokers).

Results: BAL revealed the microorganisms with potential pathogenicity above the established threshold (> or = 10(3)cfu/ml) in 68.4% of patients with frequent exacerbation, 55% of infrequent exacerbation, 40% of smokers and 12.5% of non-smokers controls (P=0.05). BAL MPO, IL-8 and TNF-alpha levels were found to be significantly higher in COPD as compared to controls (P=0.001). However, only IL-8 level was significantly higher in COPD patients with frequent exacerbation as compared to infrequent (P=0.001). Airway bacterial load correlated with levels of airway inflammation markers in COPD (P<0.05).

Conclusion: The bacterial load and airway inflammation contributes to each other in stable COPD. However, there is a link only between interleukine (IL)-8 and frequent exacerbations. Clearly, the relationship between bacterial colonization, airway inflammation and frequent exacerbations is of major importance in understanding of the COPD pathogenesis.

MeSH terms

  • Biomarkers / analysis
  • Bronchoalveolar Lavage Fluid / chemistry*
  • Bronchoalveolar Lavage Fluid / microbiology
  • Female
  • Humans
  • Interleukin-18 / analysis
  • Leukocyte Elastase / analysis
  • Male
  • Middle Aged
  • Peroxidase / analysis
  • Prospective Studies
  • Pulmonary Disease, Chronic Obstructive / immunology*
  • Pulmonary Disease, Chronic Obstructive / microbiology
  • Pulmonary Disease, Chronic Obstructive / physiopathology
  • Respiratory Function Tests
  • Smoking / immunology
  • Tumor Necrosis Factor-alpha / analysis


  • Biomarkers
  • Interleukin-18
  • Tumor Necrosis Factor-alpha
  • Peroxidase
  • Leukocyte Elastase