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Updated: Jun 6, 2025
Metabolic Characterization of Polarized M1 and M2 Bone Marrow-derived Macrophages Using Real-time Extracellular Flux Analysis
Published on: November 28, 2015
Myeloid DRP1 deficiency limits revascularization in ischemic muscles via inflammatory macrophage polarization and
Shikha Yadav1, Vijay C Ganta1,2, Sudhahar Varadarajan1,3,4
1Vascular Biology Center.
Abstract:
Macrophages play a crucial role in promoting perfusion recovery and revascularization after ischemia through antiinflammatory polarization, a process essential for the treatment of peripheral artery disease (PAD). Mitochondrial dynamics, particularly regulated by the fission protein DRP1, are closely linked to macrophage metabolism and inflammation. However, the role of DRP1 in reparative neovascularization remains unexplored. Here, we show that DRP1 expression was increased in F4/80+ macrophages within ischemic muscle on day 3 after hind limb ischemia (HLI), an animal model of PAD. Mice lacking Drp1 in myeloid cells exhibited impaired limb perfusion recovery, angiogenesis, and muscle regeneration after HLI. These effects were associated with increased proinflammatory M1-like macrophages, p-NF-κB, and TNF-α, and reduced antiinflammatory M2-like macrophages and p-AMPK in ischemic muscle of myeloid Drp1-/- mice. In vitro, Drp1-deficient macrophages under hypoxia serum starvation (HSS), an in vitro PAD model, demonstrated enhanced glycolysis via reducing p-AMPK as well as mitochondrial dysfunction, and excessive mitochondrial ROS production, resulting in increased proinflammatory M1-gene and reduced antiinflammatory M2-gene expression. Conditioned media from HSS-treated Drp1-/- macrophages exhibited increased proinflammatory cytokine secretion, leading to suppressed angiogenesis in endothelial cells. Thus, macrophage DRP1 deficiency under ischemia drives proinflammatory metabolic reprogramming and macrophage polarization, limiting revascularization in experimental PAD.
Insights
Mitochondrial fission protein DRP1 in macrophages is vital for repairing tissue after peripheral artery disease (PAD). Lack of DRP1 impairs healing by promoting inflammation and hindering blood vessel growth.
Area of Science:
- Cell Biology
- Immunology
- Vascular Biology
Background:
- Macrophages are key to tissue repair after ischemia, particularly in peripheral artery disease (PAD).
- Mitochondrial dynamics, regulated by DRP1, influence macrophage function and inflammation.
- The specific role of DRP1 in macrophage-driven neovascularization is not well understood.
Purpose of the Study:
- To investigate the role of DRP1 in myeloid cells during the repair of ischemic tissue.
- To determine how DRP1 deficiency in macrophages affects inflammation, metabolism, and angiogenesis in experimental PAD.
Main Methods:
- Utilized a mouse model of hind limb ischemia (HLI) to mimic PAD.
- Generated myeloid-specific DRP1 knockout mice (myeloid Drp1-/-).
- Assessed limb perfusion, angiogenesis, muscle regeneration, macrophage polarization, and molecular markers in vivo and in vitro.
Main Results:
- Myeloid DRP1 deficiency impaired limb perfusion recovery, angiogenesis, and muscle regeneration post-HLI.
- DRP1-deficient macrophages showed increased M1 (proinflammatory) polarization and reduced M2 (anti-inflammatory) polarization.
- In vitro, DRP1-deficient macrophages exhibited enhanced glycolysis, mitochondrial dysfunction, increased ROS production, and elevated proinflammatory cytokine secretion, suppressing endothelial cell angiogenesis.
Conclusions:
- Macrophage DRP1 is crucial for promoting anti-inflammatory polarization and metabolic reprogramming necessary for neovascularization in PAD.
- DRP1 deficiency in macrophages under ischemic conditions drives a proinflammatory state, hindering tissue repair and revascularization.
- Targeting macrophage DRP1 may offer a therapeutic strategy for improving outcomes in peripheral artery disease.
