The present invention relates to methods of treating or preventing respiratory infections, in particular respiratory infections in patients with an underlying respiratory disorder such as chronic obstructive pulmonary disease (COPD). The present invention also relates to methods of treating or preventing COPD or COPD exacerbations. The invention particularly describes the role of Notch 3 and/or Notch 4 signalling in such methods and the use of Notch 3 and/or Notch 4 as therapeutic and screening targets.
