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Published on: October 22, 2019
Altered macrophage function in chronic obstructive pulmonary disease
11 Department of Pulmonology, Leiden University Medical Centre, Leiden, The Netherlands.
Abstract:
The observation that macrophages are increased in chronic obstructive pulmonary disease (COPD) and are associated with COPD severity has led to a large number of studies on macrophage function in COPD. These studies have provided evidence that these cells contribute to tissue injury through the release of various mediators, including proteases such as matrix metalloprotease-12. In addition, it was found that macrophages in COPD have an impaired ability to clear respiratory pathogens and apoptotic cells. Macrophage phagocytic function in COPD can be restored at least in part, as shown by in vitro studies. In a search to further understand this altered function of macrophages in COPD, several studies have used a range of markers to phenotype macrophages in COPD. Macrophages constitute a heterogeneous cell population, and, currently, proinflammatory M1 and anti-inflammatory M2 and M2-like cells are considered to represent the extremes of a pattern of macrophage polarization. In COPD, there is no clear evidence for a predominance of one of these phenotypes, and an intermediate phenotype may be present. Future studies are needed to establish the nature of this apparent COPD-specific macrophage subset, and to link macrophage dysfunction to COPD phenotypes.
Insights
Macrophages in chronic obstructive pulmonary disease (COPD) are increased and impair pathogen clearance. While their function can be restored in vitro, a COPD-specific subset may exist, requiring further research to link dysfunction to disease phenotypes.
Area of Science:
- Pulmonary Medicine
- Immunology
- Cell Biology
Background:
- Macrophages are elevated in chronic obstructive pulmonary disease (COPD) and linked to disease severity.
- These immune cells contribute to lung tissue injury via mediators like matrix metalloprotease-12.
- Macrophage dysfunction in COPD includes impaired clearance of pathogens and apoptotic cells.
Purpose of the Study:
- To investigate the altered function and phenotype of macrophages in COPD.
- To understand the heterogeneity of macrophage populations in COPD.
- To explore potential COPD-specific macrophage subsets.
Main Methods:
- Review of studies on macrophage function and phenotyping in COPD.
- Analysis of macrophage polarization markers (M1, M2, M2-like).
- Consideration of in vitro studies demonstrating partial restoration of macrophage function.
Main Results:
- Macrophages in COPD exhibit impaired phagocytic capacity.
- Evidence suggests a potential intermediate or COPD-specific macrophage phenotype, not a clear M1 or M2 predominance.
- In vitro studies indicate that macrophage function can be partially restored.
Conclusions:
- Macrophage dysfunction is a key feature of COPD, contributing to disease pathology.
- Further research is necessary to characterize the proposed COPD-specific macrophage subset.
- Linking specific macrophage phenotypes and dysfunction to distinct COPD phenotypes is a critical future direction.
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