title: Lower airway colonization and inflammatory response in COPD: a focus on Haemophilus influenzae.
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.
authors.affiliation: Airway Disease Infection Section, National Heart and Lung Institute, Imperial College, London, United Kingdom.
authors.forename: Lydia J
authors.initials: LJ
authors.lastname: Finney
authors.affiliation: Airway Disease Infection Section, National Heart and Lung Institute, Imperial College, London, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Ritchie
authors.affiliation: King's College London, London, United Kingdom.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Pollard
authors.affiliation: Airway Disease Infection Section, National Heart and Lung Institute, Imperial College, London, United Kingdom.
authors.forename: Sebastian L
authors.initials: SL
authors.lastname: Johnston
authors.affiliation: Airway Disease Infection Section, National Heart and Lung Institute, Imperial College, London, United Kingdom.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mallia
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D006192:Haemophilus Infections / Q000276:immunology / Q000382:microbiology* / Q000503:physiopathology / Q000517:prevention & control; D018073:Haemophilus Vaccines / Q000627:therapeutic use; D006193:Haemophilus influenzae / Q000276:immunology / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D006801:Humans; D007113:Immunity, Innate; D008168:Lung / Q000276:immunology / Q000382:microbiology* / Q000503:physiopathology; D029424:Pulmonary Disease, Chronic Obstructive / Q000276:immunology / Q000382:microbiology* / Q000503:physiopathology / Q000628:therapy; D012141:Respiratory Tract Infections / Q000276:immunology / Q000382:microbiology* / Q000503:physiopathology / Q000628:therapy
chemical_list: D018073:Haemophilus Vaccines
keywords: Haemophilus influenzae; chronic obstructive pulmonary disease; nontypeable Haemophilus influenzae; respiratory viruses; vaccination