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Review

Lower airway colonization and inflammatory response in COPD: a focus on Haemophilus influenzae

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Pages 1119-1132 | Published online: 13 Oct 2014
 

Abstract

Bacterial infection of the lower respiratory tract in chronic obstructive pulmonary disease (COPD) patients is common both in stable patients and during acute exacerbations. The most frequent bacteria detected in COPD patients is Haemophilus influenzae, and it appears this organism is uniquely adapted to exploit immune deficiencies associated with COPD and to establish persistent infection in the lower respiratory tract. The presence of bacteria in the lower respiratory tract in stable COPD is termed colonization; however, there is increasing evidence that this is not an innocuous phenomenon but is associated with airway inflammation, increased symptoms, and increased risk for exacerbations. In this review, we discuss host immunity that offers protection against H. influenzae and how disturbance of these mechanisms, combined with pathogen mechanisms of immune evasion, promote persistence of H. influenzae in the lower airways in COPD. In addition, we examine the role of H. influenzae in COPD exacerbations, as well as interactions between H. influenzae and respiratory virus infections, and review the role of treatments and their effect on COPD outcomes. This review focuses predominantly on data derived from human studies but will refer to animal studies where they contribute to understanding the disease in humans.

Disclosure

SLJ has received institutional funding for clinical trials and research grants and consultant compensation from Centocor, Sanofi, Pasteur, GlaxoSmithKline, Chiesi, Boehringer Ingelheim, Novartis, and Synairgen, as well as consultant compensation from Grünenthal, and has share options in Synairgen. PM has received speaker’s fees and travel grants from GlaxoSmithKline and Novartis. The other authors report no conflicts of interest in this work.