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Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages
Published on: June 23, 2013
M2 macrophage-secreted exosomal miR-216a regulates microglial polarization by targeting the HMGB1/TLR4/NF-κB pathway
Shilin Cao1, Haihe Yang2, Peiyao Li1
1Department of Pain, First Affiliated Hospital of Kunming Medical University Kunming 650000, Yunnan, China.
Objective:
M2 macrophage-derived exosomes (M2-exos) hold promise for patients with bone cancer pain (BCP). This study aimed to investigate the therapeutic effect and related mechanisms of M2-exos in both in vitro and in vivo models of BCP.
Method:
RAW 264.7 macrophages were treated with IL-4 to generate M2-polarized macrophages. M2-exos were characterized by transmission electron microscope and Western blotting. A mouse model of BCP was established, and BV2 microglia were activated by lipopolysaccharide stimulation. The effects of M2-exos were evaluated in vitro by coculture with reactive BV2 microglia and in vivo by microinjection into the rostral ventromedial medulla (RVM) of BCP mice. CCK-8 assays, ELISAs, flow cytometry and immunofluorescence were used to determine the effects of M2-exos on microglial activation. The therapeutic effects of M2-exos were evaluated via pain behavior experiments. Bioinformatic analysis and rescue experiments were performed to investigate the mechanisms through which M2-exos affect the progression of BCP.
Results:
In vitro, M2-exos administration repolarized microglial toward the anti-inflammatory M2 phenotype in coculture systems. In vivo analysis indicated that microinjection of M2-exos into the RVM region improved neuroinflammation. Notably, miR-216a expression was significantly increased in M2-exos and could be delivered into BV2 microglia. Blockade of miR-216a abolished the therapeutic effects of M2-exos in vitro and in vivo. Mechanistically, miR-216a negatively regulates high mobility group Box 1 protein (HMGB1) expression, further inhibiting Toll-like receptor 4 (TLR4)/NF-κB and inducing M2 microglial polarization, thereby delaying BCP progression.
Conclusion:
M2 macrophage-derived exosomal miR-216a could delay BCP progression by targeting HMGB1/TLR4/NF-κB-mediated microglial M2 polarization.
Insights
M2 macrophage-derived exosomes show therapeutic potential for bone cancer pain (BCP). Exosomal miR-216a delays BCP by targeting HMGB1/TLR4/NF-κB, promoting anti-inflammatory M2 microglial polarization.
Area of Science:
- Cell Biology
- Neuroscience
- Oncology
Background:
- Bone cancer pain (BCP) poses a significant clinical challenge.
- Exosomes derived from M2 macrophages (M2-exos) are emerging as potential therapeutic agents.
- Understanding the mechanisms of M2-exos in BCP is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the therapeutic effects of M2-exos on bone cancer pain (BCP).
- To elucidate the underlying mechanisms of M2-exos in BCP models, focusing on microglial polarization.
Main Methods:
- M2-polarized macrophages were generated and their exosomes (M2-exos) characterized.
- In vitro and in vivo models of BCP were established, involving BV2 microglia and a mouse model.
- M2-exos were administered, and their effects on microglial activation, neuroinflammation, and pain behaviors were assessed using various assays and techniques.
Main Results:
- M2-exos administration repolarized microglia to an anti-inflammatory M2 phenotype in vitro and reduced neuroinflammation in vivo.
- miR-216a, enriched in M2-exos, was identified as a key mediator, delivering into microglia and blocking its function abolished therapeutic effects.
- Mechanistically, miR-216a targets HMGB1, inhibiting the TLR4/NF-κB pathway and promoting M2 microglial polarization, thereby delaying BCP progression.
Conclusions:
- M2 macrophage-derived exosomal miR-216a demonstrates significant therapeutic potential for delaying bone cancer pain progression.
- The mechanism involves targeting HMGB1 and the TLR4/NF-κB pathway to induce M2 microglial polarization, reducing neuroinflammation.
- These findings highlight M2-exos as a promising cell-free therapy for managing bone cancer pain.
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