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Updated: Sep 21, 2025
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The Use of Mouse Splenocytes to Assess Pathogen-associated Molecular Pattern Influence on Clock Gene Expression
Published on: July 24, 2018
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Macrophage circadian rhythms are differentially affected based on stimuli.
Sujeewa S Lellupitiyage Don1, Javier A Mas-Rosario2, Hui-Hsien Lin1
1Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, USA.
Summary
Macrophage polarization to M1 or M2 states alters their internal circadian rhythms. Cancer cell-conditioned media also impacts macrophage circadian patterns, revealing a complex interplay between immunity and cancer biology.
Area of Science:
- Immunology
- Chronobiology
- Cancer Biology
Background:
- Macrophages are crucial immune cells with dynamic phenotypes (M1/M2) influencing health and disease.
- Circadian rhythms, the body's ~24-hour cycles, regulate ~8-15% of the macrophage transcriptome.
- The relationship between macrophage polarization and circadian clock function remains largely unexplored.
Purpose of the Study:
- To investigate how macrophage polarization to distinct subtypes (M1 vs. M2) affects their molecular circadian rhythms.
- To determine the impact of cancer cell-derived factors on macrophage circadian patterns.
- To explore how macrophage-conditioned media influences the circadian rhythms of cancer cells.
Main Methods:
- RAW 264.7 macrophages were stably transfected with Bmal1:luc and Per2:luc circadian reporters.
- Macrophage polarization was induced using M1 and M2 stimuli.
- Circadian rhythmicity, period, and amplitude were analyzed using luminescence assays.
- Conditioned media from mouse breast cancer cells (4T1, EMT6) and RAW 264.7 macrophages were applied to reporter cells.
Main Results:
- M1 polarization reduced rhythmicity and amplitude of circadian reporters, while M2 polarization increased period length.
- Conditioned media from aggressive 4T1 cancer cells abolished macrophage rhythmicity.
- Macrophage-conditioned media altered circadian rhythms in human osteosarcoma cells (U2OS-Per2:luc), decreasing rhythmicity and period but increasing amplitude.
- Macrophages exposed to breast cancer media exhibited M1-like circadian phenotypes.
Conclusions:
- Macrophage polarization states significantly impact their intrinsic circadian clock characteristics.
- There is a bidirectional crosstalk between macrophages and cancer cells affecting circadian rhythms.
- Circadian alterations in macrophages may be linked to their M1-like phenotype in the tumor microenvironment.
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