Chronic obstructive pulmonary disease (COPD) is characterised by persistent airway inflammation, with increased numbers of macrophages and neutrophils. Some patients become colonised with bacteria including Haemophilus influenza and Moraxella catarrhalis. The ability of the innate immune system to clear bacteria is compromised. A subset of COPD patients show eosinophilic airway inflammation, with less presence of bacteria. The treatment of COPD is moving towards a personalised approach, depending on the nature of airway inflammation and the underlying mechanisms responsible.

The specific aims are (1) To investigate the differences in bacterial colonisation and airway inflammation in early stage compared to severe COPD using sputum and bronchoscopic sampling (2) To develop biomarkers of lung neutrophil activation in COPD patients (3) To identify the mechanisms of susceptibility to infection in COPD patients with persistent bacterial colonisation.