Arthritis-associated osteoclastogenic macrophage, AtoM, as a key player in pathological bone erosion
Tomoya Agemura1, Tetsuo Hasegawa1, Shinya Yari1
1Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan.
Abstract:
Osteoclasts are myeloid lineage cells with a unique bone-destroying ability that maintains bone homeostasis together with bone formation by osteoblasts. An advanced intravital imaging system using a two-photon microscopy has enabled the observation and evaluation of osteoclast dynamics and behaviors in the bone marrow of living mice. Using this system, it has become clear that pathological osteoclasts under inflamed conditions differ from physiological osteoclasts under a steady-state. Recently, we identified novel osteoclast precursors in arthritis, called arthritis-associated osteoclastogenic macrophages (AtoMs), which differentiate into pathological osteoclasts and induce inflammatory bone destruction. In this review, we introduce the in vivo imaging of physiological and pathological osteoclasts and their differentiation mechanism.
Insights
Researchers identified novel arthritis-associated osteoclastogenic macrophages (AtoMs) that drive inflammatory bone destruction. Advanced imaging reveals differences between physiological and pathological osteoclasts in living mice.
Area of Science:
- Bone Biology
- Immunology
- Cellular Dynamics
Background:
- Osteoclasts are crucial myeloid cells for bone homeostasis, balancing bone formation by osteoblasts.
- Pathological osteoclasts, distinct from physiological ones, contribute to bone destruction under inflammation.
- Understanding osteoclast behavior in vivo is key to addressing bone diseases.
Purpose of the Study:
- To review in vivo imaging techniques for observing osteoclast dynamics.
- To elucidate the differentiation mechanisms of physiological and pathological osteoclasts.
- To introduce novel osteoclast precursors identified in arthritis.
Main Methods:
- Utilizing advanced two-photon intravital microscopy for real-time observation of osteoclasts in living mouse bone marrow.
- Characterizing osteoclast precursors in arthritic conditions.
Main Results:
- Intravital imaging revealed distinct dynamics between physiological and pathological osteoclasts.
- Identified arthritis-associated osteoclastogenic macrophages (AtoMs) as novel precursors.
- AtoMs differentiate into pathological osteoclasts, causing inflammatory bone destruction.
Conclusions:
- Arthritis-associated osteoclastogenic macrophages (AtoMs) are key players in inflammatory bone loss.
- In vivo imaging provides critical insights into osteoclast function and differentiation.
- Targeting AtoMs may offer a therapeutic strategy for inflammatory bone diseases.
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