Impact of sputum bacteria on airway inflammation and health status in clinical stable COPD

Abstract

Chronic obstructive pulmonary disease (COPD) is characterised by sputum production, bacterial colonisation, neutrophilic bronchial airway inflammation and poor health status. The aim of this study was to determine the impact of sputum potentially pathogenic microorganisms (PPMs) on bronchial airway inflammation, health status and plasma fibrinogen levels in subjects with moderate-to-severe COPD during the clinical stable state. Sputum total cell and neutrophil counts, supernatant interleukin-8, leukotriene B4, tumour necrosis factor-alpha and neutrophil elastase levels, neutrophil chemotaxis and plasma fibrinogen levels were estimated. Health status was determined using the St George's Respiratory Questionnaire and the 36-item Short-Form Health Survey questionnaire. Twenty-seven (40%) subjects had PPMs and 40 (60%) non-PPMs in their sputum. Both groups were of similar age, body mass index, smoking history and lung function. The PPMs group showed significantly higher levels of interleukin-8, leukotriene B4, tumour necrosis factor-a, neutrophil elastase and increased neutrophil chemotaxis. They also exhibited worse health status and raised plasma fibrinogen levels compared to the non-PPMs group. In conclusion, subjects with clinically stable moderate-to-severe chronic obstructive pulmonary disease who had potentially pathogenic microorganisms in their sputum demonstrated an exaggerated airway inflammatory response, poorer health status and increased plasma fibrinogen levels than those who had nonpotentially pathogenic microorganisms.