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Monocytes and Macrophages in COVID-19
Rainer Knoll1,2, Joachim L Schultze1,2,3, Jonas Schulte-Schrepping1,2
1Systems Medicine, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany.
Frontiers in Immunology
|August 9, 2021
Summary
Monocytes and macrophages play crucial roles in COVID-19. In severe cases, these immune cells exhibit dysfunction and hyperactivation, worsening lung damage and inflammation.
Area of Science:
- Immunology
- Virology
- Pathology
Background:
- COVID-19, caused by SARS-CoV-2, is a global pandemic with significant health and socioeconomic impacts.
- Macrophages and monocytes are critical immune cells involved in host defense, inflammation, and tissue repair.
- Understanding their role in viral infections like COVID-19 is vital for disease management.
Purpose of the Study:
- To review current knowledge on monocyte and macrophage function in homeostasis and viral infections.
- To summarize key findings regarding the role of monocytes and macrophages in COVID-19 pathogenesis.
- To elucidate the phenotypic changes and functional consequences of these cells in COVID-19.
Main Methods:
- Literature review of studies on monocytes and macrophages in viral infections.
- Analysis of existing research on immune cell phenotypes in COVID-19 patients.
- Synthesis of findings on monocyte and macrophage roles in COVID-19 pathophysiology.
Main Results:
- In moderate COVID-19, blood monocytes show an inflammatory, interferon-stimulated gene (ISG)-driven phenotype.
- In severe COVID-19, monocytes exhibit cellular dysfunction, including loss of HLA-DR and increased S100 alarmin expression.
- Pulmonary macrophages in COVID-19 are hyperactivated, contributing to a cycle of inflammation and tissue damage.
Conclusions:
- Monocyte and macrophage phenotypes are significantly altered in COVID-19, correlating with disease severity.
- Dysfunctional and hyperactivated monocytes/macrophages contribute to the exaggerated inflammatory response and tissue damage seen in severe COVID-19.
- Targeting these immune cells may offer therapeutic strategies for managing COVID-19.
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