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Updated: May 19, 2026

Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages
Published on: June 23, 2013
Classical macrophage activation up-regulates several matrix metalloproteinases through mitogen activated protein
Wei-Chun Huang1, Graciela B Sala-Newby, Angela Susana
1Bristol Heart Institute, University of Bristol, Bristol, United Kingdom.
Abstract:
Remodelling of the extracellular matrix (ECM) and cell surface by matrix metalloproteinases (MMPs) is an important function of monocytes and macrophages. Recent work has emphasised the diverse roles of classically and alternatively activated macrophages but the consequent regulation of MMPs and their inhibitors has not been studied comprehensively. Classical activation of macrophages derived in vitro from un-fractionated CD16(+/-) or negatively-selected CD16(-) macrophages up-regulated MMP-1, -3, -7, -10, -12, -14 and -25 and decreased TIMP-3 steady-state mRNA levels. Bacterial lipopolysaccharide, IL-1 and TNFα were more effective than interferonγ except for the effects on MMP-25, and TIMP-3. By contrast, alternative activation decreased MMP-2, -8 and -19 but increased MMP -11, -12, -25 and TIMP-3 steady-state mRNA levels. Up-regulation of MMPs during classical activation depended on mitogen activated protein kinases, phosphoinositide-3-kinase and inhibitor of κB kinase-2. Effects of interferonγ depended on janus kinase-2. Where investigated, similar effects were seen on protein concentrations and collagenase activity. Moreover, activity of MMP-1 and -10 co-localised with markers of classical activation in human atherosclerotic plaques in vivo. In conclusion, classical macrophage activation selectively up-regulates several MMPs in vitro and in vivo and down-regulates TIMP-3, whereas alternative activation up-regulates a distinct group of MMPs and TIMP-3. The signalling pathways defined here suggest targets for selective modulation of MMP activity.
Insights
Classical macrophage activation up-regulates matrix metalloproteinases (MMPs) and down-regulates TIMP-3, while alternative activation affects distinct MMPs and TIMP-3. This study identifies key signaling pathways for modulating MMP activity.
Area of Science:
- Immunology and Molecular Biology
- Extracellular Matrix Biology
Background:
- Monocytes and macrophages remodel the extracellular matrix (ECM) via matrix metalloproteinases (MMPs).
- Distinct roles of classically and alternatively activated macrophages are recognized, but their regulation of MMPs and inhibitors is not fully understood.
Purpose of the Study:
- To comprehensively investigate the regulation of MMPs and their inhibitors (TIMPs) by classical and alternative macrophage activation.
- To identify the signaling pathways involved in MMP regulation during macrophage activation.
Main Methods:
- In vitro differentiation of macrophages (CD16+/- and CD16-) and stimulation with LPS, IL-1, TNFα, and IFNγ.
- Analysis of steady-state mRNA levels for MMPs and TIMP-3.
- Investigation of signaling pathways including MAPKs, PI3K, IKK-2, and JAK-2.
- In vivo assessment of MMP activity in human atherosclerotic plaques.
Main Results:
- Classical activation up-regulated MMP-1, -3, -7, -10, -12, -14, -25 and decreased TIMP-3 mRNA.
- Alternative activation decreased MMP-2, -8, -19 but increased MMP-11, -12, -25, and TIMP-3 mRNA.
- Classical activation-induced MMPs were dependent on MAPKs, PI3K, and IKK-2; IFNγ effects involved JAK-2. MMP-1 and -10 activity correlated with classical activation markers in atherosclerotic plaques.
Conclusions:
- Classical macrophage activation selectively up-regulates specific MMPs and down-regulates TIMP-3, both in vitro and in vivo.
- Alternative activation induces a distinct set of MMPs and TIMP-3.
- The identified signaling pathways offer potential targets for selective modulation of MMP activity.
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