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Respir Res. 2014 Jun 27;15:72. doi: 10.1186/1465-9921-15-72.

Impaired macrophage phagocytosis of bacteria in severe asthma.

Author information

1
Airway Disease, National Heart and Lung Institute, Imperial College London, & Biomedical Research Unit, Royal Brompton & Harefield NHS Trust, London SW3, UK. p.bhavsar@imperial.ac.uk.

Abstract

BACKGROUND:

Bacteria are frequently cultured from sputum samples of severe asthma patients suggesting a defect in bacterial clearance from the airway. We measured the capacity of macrophages from patients with asthma to phagocytose bacteria.

METHODS:

Phagocytosis of fluorescently-labelled polystyrene beads, Haemophilus influenzae or Staphylococcus aureus by broncholaveolar lavage alveolar macrophages (AM) and by monocyte-derived macrophages (MDM) from non-asthmatics, mild-moderate and severe asthmatic patients was assessed using fluorimetry.

RESULTS:

There were no differences in phagocytosis of polystyrene beads by AMs or MDMs from any of the subject groups. There was reduced phagocytosis of Haemophilus influenzae and Staphylococcus aureus in MDMs from patients with severe asthma compared to non-severe asthma (p < 0.05 and p < 0.01, respectively) and healthy subjects (p < 0.01and p < 0.001, respectively). Phagocytosis of Haemophilus influenzae and Staphylococcus aureus by AM was also reduced in severe asthma compared to normal subjects (p < 0.05). Dexamethasone and formoterol did not suppress phagocytosis of bacteria by MDMs from any of the groups.

CONCLUSIONS:

Persistence of bacteria in the lower airways may result partly from a reduced phagocytic capacity of macrophages for bacteria. This may contribute to increased exacerbations, airway colonization and persistence of inflammation.

PMID:
24972601
PMCID:
PMC4086996
DOI:
10.1186/1465-9921-15-72
[Indexed for MEDLINE]
Free PMC Article

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