Sputum macrophage diversity and activation in asthma: role of severity and inflammatory phenotype
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Published version
Author(s)
Type
Journal Article
Abstract
BACKGROUND: Macrophages control innate and acquired immunity but their role in severe asthma remains ill-defined. We investigated gene signatures of macrophage subtypes in the sputum of 104 asthmatics and 16 healthy volunteers from the U-BIOPRED cohort. METHODS: Forty-nine gene signatures (modules) for differentially stimulated macrophages, one to assess lung tissue-resident cells (TR-Mφ) and two for their polarization (classically- and alternatively-activated macrophages: M1 and M2 respectively) were studied using gene set variation analysis. We calculated enrichment scores (ES) across severity and previously identified asthma transcriptome-associated clusters (TACs). RESULTS: Macrophage numbers were significantly decreased in severe asthma compared to mild-moderate asthma and healthy volunteers. The ES for most modules were also significantly reduced in severe asthma except for 3 associated with inflammatory responses driven by TNF and Toll-like receptors via NF-κB, eicosanoid biosynthesis via the lipoxygenase pathway and IL-2 biosynthesis (all p<0.01). Sputum macrophage number and the ES for most macrophage signatures were higher in the TAC3 group compared to TAC1 and TAC2 asthmatics. However, a high enrichment was found in TAC1 for 3 modules showing inflammatory pathways linked to Toll-like and TNF receptor activation and arachidonic acid metabolism (p<0.001) and in TAC2 for the inflammasome- and interferon-signalling pathways (p<0.001). Data was validated in the ADEPT cohort. Module analysis provides additional information compared to conventional M1 and M2 classification. TR-Mφ were enriched in TAC3 and associated with mitochondrial function. CONCLUSIONS: Macrophage activation is attenuated in severe granulocytic asthma highlighting defective innate immunity except for specific subsets characterised by distinct inflammatory pathways.
Date Issued
2021-03-01
Date Acceptance
2020-06-27
Citation
Allergy, 2021, 76 (3), pp.775-788
ISSN
0105-4538
Publisher
John Wiley and Sons
Start Page
775
End Page
788
Journal / Book Title
Allergy
Volume
76
Issue
3
Copyright Statement
© 2020 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd
This is an open access article under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This is an open access article under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Sponsor
Commission of the European Communities
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/32740964
Grant Number
115010
Subjects
gene set variation analysis
macrophage subtypes
sputum
tissue-resident macrophage
Publication Status
Published
Coverage Spatial
Denmark
Date Publish Online
2020-08-01