Impaired macrophage phagocytosis in non-eosinophilic asthma

Simpson, J. L., Gibson, P. G., Yang, I. A., Upham, J., James, A., Reynolds, P. N., Hodge, S. and AMAZES Study Research Group (2013) Impaired macrophage phagocytosis in non-eosinophilic asthma. Clinical and Experimental Allergy, 43 1: 29-35. doi:10.1111/j.1365-2222.2012.04075.x


Author Simpson, J. L.
Gibson, P. G.
Yang, I. A.
Upham, J.
James, A.
Reynolds, P. N.
Hodge, S.
AMAZES Study Research Group
Total Author Count Override 7
Title Impaired macrophage phagocytosis in non-eosinophilic asthma
Journal name Clinical and Experimental Allergy   Check publisher's open access policy
ISSN 0954-7894
1365-2222
Publication date 2013-01
Year available 2012
Sub-type Article (original research)
DOI 10.1111/j.1365-2222.2012.04075.x
Open Access Status
Volume 43
Issue 1
Start page 29
End page 35
Total pages 7
Place of publication Chichester, West Sussex, United Kingdom
Publisher Wiley-Blackwell
Collection year 2013
Language eng
Formatted abstract
Background: Many patients with non-eosinophilic asthma have increased numbers of neutrophils in the airways. The explanation for this chronic inflammation remains unclear, but may result from an impaired ability of alveolar macrophages to phagocytose apoptotic cells (a process termed 'efferocytosis'), as we have shown in chronic obstructive pulmonary disease (COPD).

Objectives: To examine induced sputum as a non-invasive technique to characterize efferocytosis in chronic lung diseases and to compare efferocytosis in patients with non-eosinophilic asthma, eosinophilic asthma and COPD.

Methods: Participants with stable asthma (20 with eosinophilic and 30 with non-eosinophilic) and COPD (n = 11) underwent clinical assessment including allergy skin tests, saline challenge and sputum induction. Sputum cells were dispersed using dithiothreitol and resuspended in culture medium. Efferocytosis of apoptotic bronchial epithelial cells by sputum-derived macrophages was determined using flow cytometry.

Results: There were no significant differences in efferocytosis between paired sputum and bronchoalveolar lavage macrophages from three subjects. Efferocytosis was significantly impaired in patients with non-eosinophilic asthma [mean (SD) 0.95 (0.24)] compared with eosinophilic asthma [1.17 (0.19)] and to a similar degree as patients with COPD [1.04 (0.16)]. Sputum neutrophils were significantly higher in patients with COPD and non-eosinophilic asthma compared with eosinophilic asthma.

Conclusion and Clinical Relevance:
Induced sputum provides a reliable and non-invasive method for studying macrophage efferocytosis in chronic lung disease. Macrophage efferocytosis is impaired in non-eosinophilic asthma to a similar degree as that in COPD and may explain the persistent airway neutrophilia and chronic inflammation that characterizes this asthma subtype.
Keyword Non-eosinophilic asthma
Neutrophils
Efferocytosis
Induced sputum
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Article first published online: 24 December 2012.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Medicine Publications
 
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