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Updated: Aug 19, 2025
Assessing Anti-fungal Activity of Isolated Alveolar Macrophages by Confocal Microscopy
Published on: July 9, 2014
Alveolar macrophage metabolic programming via a C-type lectin receptor protects against lipo-toxicity and cell death
Michal Scur1, Ahmad Bakur Mahmoud2, Sayanti Dey1
1Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada.
Abstract:
Alveolar macrophages (AM) hold lung homeostasis intact. In addition to the defense against inhaled pathogens and deleterious inflammation, AM also maintain pulmonary surfactant homeostasis, a vital lung function that prevents pulmonary alveolar proteinosis. Signals transmitted between AM and pneumocytes of the pulmonary niche coordinate these specialized functions. However, the mechanisms that guide the metabolic homeostasis of AM remain largely elusive. We show that the NK cell-associated receptor, NKR-P1B, is expressed by AM and is essential for metabolic programming. Nkrp1b-/- mice are vulnerable to pneumococcal infection due to an age-dependent collapse in the number of AM and the formation of lipid-laden AM. The AM of Nkrp1b-/- mice show increased uptake but defective metabolism of surfactant lipids. We identify a physical relay between AM and alveolar type-II pneumocytes that is dependent on pneumocyte Clr-g expression. These findings implicate the NKR-P1B:Clr-g signaling axis in AM-pneumocyte communication as being important for maintaining metabolism in AM.
Insights
Alveolar macrophages (AM) maintain lung health by managing surfactant. A newly identified NKR-P1B:Clr-g signaling pathway is crucial for AM metabolic programming and lung homeostasis.
Area of Science:
- Immunology
- Cell Biology
- Pulmonary Medicine
Background:
- Alveolar macrophages (AM) are critical for lung homeostasis, pathogen defense, and surfactant regulation.
- Mechanisms governing the metabolic homeostasis of AM are not well understood.
- Pulmonary alveolar proteinosis is a condition linked to surfactant imbalance.
Purpose of the Study:
- To investigate the role of NK cell-associated receptor, NKR-P1B, in the metabolic programming of alveolar macrophages.
- To elucidate the signaling pathways involved in AM-pneumocyte communication for metabolic maintenance.
Main Methods:
- Utilized Nkrp1b knockout (Nkrp1b-/-) mice to study AM function.
- Assessed AM uptake and metabolism of surfactant lipids.
- Investigated the interaction between AM and alveolar type-II pneumocytes, focusing on Clr-g expression.
Main Results:
- Nkrp1b-/- mice exhibited age-dependent AM collapse and lipid-laden AM, increasing vulnerability to pneumococcal infection.
- AM from Nkrp1b-/- mice showed enhanced surfactant lipid uptake but impaired metabolism.
- A signaling relay dependent on pneumocyte Clr-g expression was identified between AM and alveolar type-II pneumocytes.
Conclusions:
- NKR-P1B is essential for the metabolic programming of alveolar macrophages.
- The NKR-P1B:Clr-g signaling axis plays a vital role in AM-pneumocyte communication.
- This axis is crucial for maintaining metabolic homeostasis within alveolar macrophages and overall lung health.
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