Low tissue inhibitor of metalloproteinases 3 and high matrix metalloproteinase 14 levels defines a subpopulation of highly invasive foam-cell macrophages - PubMed (original) (raw)

Low tissue inhibitor of metalloproteinases 3 and high matrix metalloproteinase 14 levels defines a subpopulation of highly invasive foam-cell macrophages

Jason L Johnson et al. Arterioscler Thromb Vasc Biol. 2008 Sep.

Abstract

Objective: An excess of metalloproteinases (MMPs) over tissue inhibitors of metalloproteinases (TIMPs) may favor atherosclerotic plaque rupture. We compared TIMP levels in nonfoamy and foam-cell macrophages (FCM) generated in vivo.

Methods and results: In vivo generated rabbit FCM exhibited 84% reduced TIMP-3 protein compared to nonfoamy macrophages, and immunocytochemistry revealed a TIMP-3 negative subset (28%). Strikingly, only TIMP-3 negative FCM invaded a synthetic basement membrane, and invasion was inhibited by exogenous TIMP-3. TIMP-3 negative FCM also had increased proliferation and apoptosis rates compared to TIMP-3 positive cells, which were retarded by exogenous TIMP-3; this also reduced gelatinolytic activity. TIMP-3 negative FCM were found at the base of advanced rabbit plaques and in the rupture-prone shoulders of human plaques. To explain the actions of low TIMP-3 we observed a 26-fold increase in MT1-MMP (MMP-14) protein in FCM. Adding an MT1-MMP neutralizing antibody reduced foam-cell invasion, apoptosis, and gelatinolytic activity. Furthermore, MT1-MMP overexpressing and TIMP-3 negative FCM were found at the same locations in atherosclerotic plaques.

Conclusions: These results demonstrate that TIMP-3 is downregulated in a distinct subpopulation of FCM which have increased MMP-14. These cells are highly invasive and have increased proliferation and apoptosis, all properties expected to destabilise atherosclerotic plaques.

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Figures

Figure 1

Figure 1

Effect of foam-cell macrophage formation and their subsequent migration on TIMP-3 protein expression. TIMP-3 expression in (A) macrophages, (B) foam-cell macrophages, and (C) foam-cell macrophages on matrigel plus exogenous TIMP-3 (arrows indicate TIMP-3 negative cells). TIMP-3 expression in (D) Nonmigrated foam-cells (black arrows) and (E) migrated foam-cells (white arrows). F, Migrated foam-cells are RAM11 positive (arrows). G, Nonimmune IgG on migrated foam-cell macrophages.

Figure 2

Figure 2

Effects of TIMP-3 expression and addition on foam-cell macrophage apoptosis. A, Exogenous TIMP-3 or a MT1-MMP neutralizing antibody inhibits foam-cell macrophage apoptosis (*P<0.05, n=3). B, Dual immunofluoresence highlights that loss of TIMP-3 expression (red) in foam-cell macrophages is associated with apoptosis as detected by cleaved caspase-3 (green). Quantification is summarized in the adjoining graph (*P<0.05, n=4).

Figure 3

Figure 3

Effect of exogenous TIMP-3 and MT1-MMP inhibition on foam-cell macrophage gelatinolytic activity. A, Exogenous TIMP-3 or a MT1-MMP neutralizing antibody inhibits foam-cell macrophage gelatinolytic activity (green), as indicated by white arrows. Quantification is summarized in the adjoining graph (*P<0.05, n=3). B and C, MT1-MMP expression of non-(arrows) and migrated (arrowheads) foam-cell macrophages from Matrigel-coated transwell inserts.

Figure 4

Figure 4

TIMP-3 localization in rabbit atherosclerotic plaques. Immunohistochemical labeling of early (A–C) and advanced (D–H) rabbit atherosclerotic plaques, for TIMP-3, macrophages (RAM11), or both. D, Nonimmune IgG control. H, Dual immunohistochemistry for macrophages (blue/green) and TIMP-3 (brown) in an advanced rabbit atherosclerotic plaque, demonstrating TIMP-3 positive macrophages (arrows) within the adventitia.

Figure 5

Figure 5

TIMP-3 localization in human advanced atherosclerotic plaques. Immunohistochemical labeling of advanced human carotid atherosclerotic plaques for macrophages (A and B) or TIMP-3 (C and D). Confocal microscopy for macrophages (F, red), TIMP-3 (G, green), and merged (H). Dual immunohistochemical labeling for cells undergoing apoptosis (green) and either TIMP-3 (red, I) or MT1-MMP (red, J).

Figure 6

Figure 6

MT1-MMP localization in rabbit atherosclerotic plaques. Immunohistochemical labeling of advanced rabbit atherosclerotic plaques, for macrophages (A and D), MT1-MMP (B and E), or TIMP-3 (C and F). Box in panels (A, B, and C) represents respective higher magnification in panels (D, E, and F). Arrows indicate immunopositive cells (brown). Dotted lines represent atherosclerotic plaque/medial boundary.

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References

    1. Newby AC. Dual role of matrix metalloproteinases (matrixins) in neointima formation and atherosclerotic plaque rupture. Physiol Rev. 2005;85:1–31. - PubMed
    1. Tedgui A, Mallat Z. Cytokines in atherosclerosis: Pathogenic and regulatory pathways. Physiol Rev. 2006;86:515–581. - PubMed
    1. Dollery CM, Libby P. Atherosclerosis and proteinase activation. Cardiovasc Res. 2006;69:625–635. - PubMed
    1. Boyle JJ, Weissberg PL, Bennett MR. Human Macrophage-Induced Vascular Smooth Muscle Cell Apoptosis Requires NO Enhancement of Fas/Fas-L Interactions. Arterioscler Thromb Vasc Biol. 2002;22:1624–1630. - PubMed
    1. Johnson JL. Matrix metalloproteinases: influence on smooth muscle cells and atherosclerotic plaque stability. Expert Rev Cardiovasc Ther. 2007;5:265–282. - PubMed

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