doi: 10.1161/hc4101.097419
(Circulation. 2001;104:1899.)
© 2001 American Heart Association, Inc.
Clinical Investigation and Reports |
Expression of Neutrophil Collagenase (Matrix Metalloproteinase-8) in Human Atheroma
A Novel Collagenolytic Pathway Suggested by Transcriptional Profiling
From The Leducq Center for Cardiovascular Research (M.P.H., G.K.S., P.L., N.G., D.B.H., M.K., U.S.), Cardiovascular Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Mass, and Millennium Pharmaceuticals, Inc (N.T., R.E.B., M.C.), Cambridge, Mass.
Correspondence to Uwe Schöbeck, Cardiovascular Medicine, Brigham and Women’s Hospital, Harvard Medical School, 221 Longwood Ave, LMRC 309, Boston, MA 02115. E-mail uschoenbeck{at}rics.bwh.harvard.edu
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Abstract |
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Background— Loss of interstitial collagen, particularly type I collagen, the major load-bearing molecule of atherosclerotic plaques, renders atheroma prone to rupture. Initiation of collagen breakdown requires interstitial collagenases, a matrix metalloproteinase (MMP) subfamily consisting of MMP-1, MMP-8, and MMP-13. Previous work demonstrated the overexpression of MMP-1 and MMP-13 in human atheroma. However, no study has yet evaluated the expression of MMP-8, known as "neutrophil collagenase," the enzyme that preferentially degrades type I collagen, because granulocytes do not localize in plaques.
Methods and Results— Transcriptional profiling and reverse transcription–polymerase chain reaction analysis revealed inducible expression of MMP-8 transcripts in CD40 ligand–stimulated mononuclear phagocytes. Western blot analysis demonstrated that 3 atheroma-associated cell types, namely, endothelial cells, smooth muscle cells, and mononuclear phagocytes, expressed MMP-8 in vitro upon stimulation with proinflammatory cytokines such as interleukin-1ß, tumor necrosis factor-
, or CD40 ligand. MMP-8 protein elaborated from these atheroma-associated cell types migrated as 2 immunoreactive bands, corresponding to the molecular weights of the zymogen and the active molecule. Extracts from atherosclerotic, but not nondiseased arterial tissue, contained similar immunoreactive bands. Moreover, all 3 cell types expressed MMP-8 mRNA and protein in human atheroma in situ. Notably, MMP-8 colocalized with cleaved but not intact type I collagen within the shoulder region of the plaque, a frequent site of rupture.
Conclusions— These data point to MMP-8 as a previously unsuspected participant in collagen breakdown, an important determinant of the vulnerability of human atheroma.
Key Words: atherosclerosis • collagen • metalloproteinases • inflammation
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Introduction |
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Rupture of atherosclerotic lesions triggers most acute clinical manifestations of atherosclerosis such as myocardial infarction or stroke.1 Previous studies established thinning and weakening of the fibrous cap as the mechanism that renders atheroma prone to rupture.2,3 Stability of the fibrous cap depends primarily on the content of intact interstitial type I collagen, the major load-bearing molecule.4 Indeed, plaques with histopathological hallmarks of vulnerability exhibit enhanced collagenolysis, a process associated with matrix metalloproteinases (MMPs).
See p 1878
Interstitial collagen fibrils resist degradation by most proteinases. Only interstitial collagenases I (MMP-1), II (MMP-8), and III (MMP-13) can initiate the breakdown of intact, triple-helical collagen, degrading types I, II, and III collagen into one-quarter and three-quarter fragments. Although collagenases have overlapping substrate specificities, MMP-1 and MMP-13 preferentially cleave type III and II collagen,5–10respectively. MMP-8, however, degrades type I collagen 3 times more potently than MMP-1 or MMP-13.11–14 After this initial cleavage, fibrillar collagen fragments become susceptible to further degradation by various MMPs overexpressed in atheroma, eg, MMP-2, MMP-3, and MMP-9.5–10
Many cell types, including endothelial cells (ECs), smooth muscle cells (SMCs), and macrophages (M
s), can express both MMP-1 and MMP-13.5–7,10 However, only polymorphonuclear granulocytes (PMNs) have been considered capable of expressing MMP-8. Originally cloned from mRNA extracted from peripheral blood leukocytes of a patient with chronic granulocytic leukemia, and later described in the postpartum murine uterus, this member of the MMP family was dubbed "neutrophil collagenase."15,16 In contrast with most MMP family members, PMN precursors synthesize MMP-8 early during differentiation and store the zymogen within special granules, which are released on PMN activation.17,18 Numerous studies have reported a role for MMP-8 in connective tissue turnover in acute inflammatory reactions involving neutrophils.17,19–21
We and others previously reported expression of the interstitial collagenases MMP-1 and MMP-13 in ECs, SMCs, and Ms in human and experimental atherosclerosis.5,7,10 We further provided direct evidence for collagenolysis in human atherosclerotic lesions and demonstrated that degraded type I collagen colocalizes with MMP-1 and MMP-13.5 Despite the preference of MMP-8 for type I collagen,11 we and others had neglected a potential role for this MMP in atherogenesis, because atheroma contain few if any neutrophils.22 However, as we report here, transcriptional profiling analysis of in vitro–differentiated peripheral blood monocyte-derived Ms stimulated with CD40 ligand (CD40L), a potent inducer of MMP expression,23–25 demonstrated the capacity of these cells to express transcripts for MMP-8. The present study reports the surprising finding that atheroma-associated ECs, SMCs, and mononuclear phagocytes express the "neutrophil" collagenase MMP-8 in vitro and in situ.
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Methods |
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Materials
Human recombinant interleukin (IL)-1ß and tumor necrosis factor (TNF)-
were obtained from Endogen, Escherichia coli endotoxin (LPS) from Sigma, and recombinant human MMP-8 and CD40L from Chemicon and Leinco Technologies, respectively.
Cell Isolation and Culture
Human vascular ECs and SMCs were isolated from saphenous veins by collagenase treatment (1 mg/mL; Worthington Biochemicals) and explant outgrowth, respectively, and were cultured as described previously.5,25 Mononuclear phagocytes were isolated from freshly prepared human peripheral blood mononuclear cells by density gradient centrifugation with lymphocyte separation medium (Organon-Teknika) and subsequent adherence to plastic culture flasks. Mononuclear phagocytes were used directly (monocytes) for the experiments or cultured for 1, 3, or 11 days (Ms) in RPMI 1640 containing 2% human serum (Sigma). The purity of monocytes/Ms wasG92%, as determined by fluorescence-activated cell sorter analysis (anti-human CD68 mAb FITC, PharMingen). Before (24 hours) and during stimulation, all 3 cell types were cultured in medium lacking serum, as described previously.5,25
PMNs were obtained from peripheral blood by venipuncture into 0.1 vol of sodium citrate anticoagulant (Sigma) with neutrophil isolation media (Cardinal Assoc) and were kindly provided by Dr M. Glogauer (Brigham and Women’s Hospital, Boston, Mass). The preparation containedG95% neutrophils as determined by hematoxylin and eosin staining.
RNA Isolation, Transcriptional Profiling, and Reverse Transcription–Polymerase Chain Reaction
Total RNA was isolated from ECs, SMCs, or in vitro–differentiated peripheral blood monocyte-derived Ms with RNazol (Tel-Test) and was reverse transcribed (Superscript Reverse Transcriptase; GibcoBRL) to obtain either the oligo-dT30 primed,[33P]dCTP-labeled first-strand cDNA probe for microarray analysis or the cDNA templates for reverse transcription–polymerase chain reaction (RT-PCR). Hybridization experiments were performed on a custom DNA array, MPG version 4.1, composed of 6144 human cDNA clones. Quadruplicate filters per probe were prehybridized (65°C, 1 hour) in 10% formamide-Church buffer containing salmon sperm DNA (10 mg/mL) and subsequently hybridized (18 hours) with the respective probe. Filters were washed twice (65°C, 15 minutes) with 2x SSC/1% SDS and 0.1x SSC/0.5% SDS, respectively, rinsed in 2x SSC, and baked (2 hours, 85°C). Finally, dried filters were exposed on phosphoimaging plates (Fuji-Film), and median intensity+SD for each probe in quadruplicate was calculated. Treatment with CD40L was compared with the respective time point of untreated control.
For RT-PCR analysis, cDNA templates (1 µL) were mixed with the respective primer pair (sense: 5'-GGAAACCCCAAG-TGGGAACG-3'; antisense: 5'-CCTGAAAGCATAGTTGG-GATACATCAAGGC-3'; 0.2 µmol/L each) in 50 µL of total reaction mixture (MgCl2 1.5 mmol/L, dNTPs 0.2 mmol/L, platinum Taq DNA polymerase 2.5 U, and 5 µL of PCR buffer). The PCR reaction mix was applied to 35 cycles at 94°C (1 minute), 55°C (1 minute), and 72°C (1.5 minutes). Aliquots of the PCR product (expected size 417 bp) were run on 1.5% agarose gels and visualized by ultraviolet transillumination. RT reaction products obtained in the absence of RT, as well as H2O, were used as mock controls.
Western Blot Analysis
Tissue extracts (50 µg of total protein per lane) obtained from frozen nonatherosclerotic (n=3) and atheromatous human carotid arteries and aortas (n=6), dichotomized a priori into fibrous (stable; n=3) and atheromatous (unstable; n=3) plaques by morphological criteria,5 as well as culture lysates (50 µg of total protein per lane) and supernatants (50 µL), were separated by SDS-PAGE under reducing conditions and applied to Western blot analysis as described previously5,25 with the respective primary (rabbit anti-human MMP-8; Chemicon) and secondary antibody. Immunoreactive proteins were visualized by the Western blot chemiluminescence system (NEN). Data were validated in additional experiments that used antibodies of different origin (mouse anti-human MMP-8; Calbiochem) and antibodies preincubated (18 hours, 4°C) with trypsin-activated recombinant human MMP-8 (5 µg/mL; Chemicon).
In Situ Hybridization
In situ hybridization was performed according to the instructions of the manufacturer (Biogenex). Frozen tissue sections of nonatherosclerotic tissue (n=3) and atheromatous plaque (n=3) specimen were fixed in cold acetone, air dried, and incubated (10 minutes, 65°C; subsequently 2 hours, 37°C) with a mixture of FITC-labeled MMP-8 (5'-TCGACAGTCTCCGACTCCATCTTTCTCGAT-3'; 5'-CGGAACGACAGAGG GTTGATACGAAAGTCC-3'; 5'-TTG-TATGAAGAAACATTTACTGGTTAAGAC-3'; 5'-TCTTGATCTAAAACCAATCTTCATTCCTAA-3') or random (control) oligomers in hybridization buffer (30% formamide, 0.6 mol/L NaCl2, 10% dextran sulfate, 50 mmol/L Tris, pH 7.5; 0.1% sodium pyrophosphate, 0.2% Ficoll, and 5 mmol/L EDTA). Finally, slides were washed 3 times and stained with alkaline phosphatase–conjugated rabbit Fab‘ anti-FITC (30 minutes) and NBT/BCIP chromogen solution (1 hour).
Immunohistochemistry
Serial cryostat sections (5 µm) of surgical specimens of 3 nonatherosclerotic aortas and carotid arteries and 6 atheromatous carotid plaques, dichotomized into stable (n=3) and vulnerable (n=3) plaques (all obtained from different donors) by morphological criteria as described previously,5 were cut, air dried onto microscope slides, fixed in acetone (-20°C, 5 minutes), and preincubated with PBS containing 0.3% hydrogen peroxide. Subsequently, sections were incubated (30 minutes) with primary (rabbit anti-human MMP-8, Chemicon) or control (rabbit Ig, Jackson Immunoresearch) antibody and processed according to the suppliers’ recommendations (LSAB Kit, Dako Co). For control purposes, staining was validated in additional experiments with an anti-MMP-8 antibody of different origin (mouse anti-human-MMP-8; Calbiochem; and mouse myeloma protein MOPC-21, Sigma).
For colocalization of MMP-8 with the respective cell type, anti-human MMP-8 antibody (1:400) was applied (90 minutes), followed by biotinylated secondary antibody (45 minutes) and Texas red–conjugated streptavidin (Amersham; 20 minutes). After application of the avidin/biotin blocking kit (Vector Laboratories), anti-muscle actin monoclonal antibody (mAb) for SMCs (1:200; Enzo Diagnostics), anti-CD31 mAb for ECs (1:35, Dako), or anti-CD68 mAb for Ms (1:500, Dako) was added and sections were incubated overnight (4°C). Subsequently, biotinylated horse anti-mouse secondary antibodies were applied (45 minutes), followed by streptavidin-FITC (Amersham; 20 minutes). Staining of type I and type III collagen used Picrosirius red, as described previously.5 Cleaved interstitial type I collagen was detected by staining with a polyclonal rabbit antibody reactive with the COL3/4Cshort neoepitope, kindly provided by Dr Robin Poole (McGill University, Montreal, Quebec, Canada).5
For immunofluorescence double labeling for MMP-8 with cleaved or intact type I collagen, frozen sections were treated as described above, with rabbit anti-human COL3/4Cshort or mouse anti-human type I collagen antibody (90 minutes) as the first antibody and mouse anti-human MMP-8 antibody (overnight, 4°C) as the second antibody. Nuclei were stained with bisbenzimide (Calbiochem).
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Results |
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Expression of MMP-8 in Human Atheroma-Associated Cells In Vitro
Transcriptional profiling demonstrated that stimulation of mononuclear phagocytes with CD40L enhanced the expression of MMP-8 transcript (Figure 1). RT-PCR revealed expression of MMP-8 transcripts in M
s, vascular SMCs (both Figure 1), and ECs (data not shown) only after stimulation, eg, via CD40L. In accord with the mRNA data, unstimulated cultures of ECs, SMCs, and mononuclear phagocytes expressed minimal or no MMP-8 protein constitutively (Figure 2). However, stimulation with proinflammatory cytokines, eg, IL-1ß or CD40L (Figure 2), as well as TNF- or LPS (data not shown), induced expression and release of immunoreactive MMP-8 in all 3 cell types. Atheroma-associated cells released 2 major MMP-8 protein species that migrated at 
75 and 55 kDa, corresponding to the latent and active forms of this enzyme, respectively. EC culture supernatants expressed only a single band at 75 kDa. In contrast, PMNs constitutively expressed cell-associated MMP-8, the release of which required stimulation. In addition to previously described inducers of secretion, we demonstrate here that ligation of CD40 on PMN triggers release of this collagenase.
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Because Ms constitute a major source of matrix-degrading proteinases, particularly interstitial collagenases within human atheroma,5,7 we further analyzed whether differentiation of freshly isolated peripheral blood mononuclear phagocytes into monocyte-derived Ms affected the expression of MMP-8. Freshly isolated mononuclear phagocytes did not release MMP-8, even when stimulated with IL-1ß or CD40L (Figure 3). However, culture for 11 days yielded low basal expression of MMP-8, which increased substantially on stimulation with either IL-1ß or CD40L.
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Expression of MMP-8 in Human Atheroma-Associated Cells In Situ
Given the inducibility of MMP-8 expression in atheroma-associated cells in vitro, we tested whether ECs, SMCs, and Ms within human atherosclerotic lesions express MMP-8 transcripts and protein in situ. In contrast to unaffected arteries, human atheroma expressed MMP-8 mRNA abundantly (Figure 4). MMP-8 localized in the M-enriched shoulder, the SMC-enriched fibrous cap, and the overlying endothelium. MMP-8 transcript expression corresponded to MMP-8 protein localization in atherosclerotic but not in nondiseased arteries (Figure 5). Like its mRNA, MMP-8 protein accumulated predominantly within the atheromatous shoulder region, a frequent site of plaque rupture. Immunofluorescence double labeling formally demonstrated colocalization of the enzyme with all 3 atheroma-associated cell types, namely, ECs, SMCs, and Ms (Figure 6).
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Interestingly, advanced atherosclerotic lesions characterized by features associated with rupture-prone plaques, eg, a large lipid core and a thin fibrous cap, expressed more immunoreactive MMP-8 than did plaques with more stable morphology or nonatherosclerotic tissue, as determined by Western blot analysis of protein extracts (Figure 7). Analysis of these samples with anti-MMP-8 antibody preincubated with the recombinant protein substantially diminished band intensities, which supports the specificity of the antibody. Semiquantitative analysis with recombinant human MMP-8 used as a standard revealed an approximate concentration of 350 ng of total immunoreactive MMP-8 per milligram of tissue in atherosclerotic lesions, levels similar to those obtained for MMP-1 and MMP-13.5 These comparisons, however, account for neither varying antibody affinities nor local accumulation of the enzyme within distinct microenvironments of the plaque, and thus their interpretations require caution. MMP-8 colocalized with the three-quarter-length type I collagen breakdown products and demonstrated an inverse correlation between the enzyme and intact type I collagen (Figure 8), which implicates MMP-8 in the processes underlying collagenolysis within the atheromatous plaque.
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Discussion |
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Degradation of extracellular matrix macromolecules, particularly interstitial type I collagen, the major load-bearing molecule within the fibrous cap of the plaque, promotes the evolution of atherosclerotic lesions toward vulnerable, rupture-prone plaques.5,6 Previous studies implicated MMPs in these degradative processes.5–10 Indeed, our group recently provided direct evidence for MMP-mediated cleavage of type I collagen within the shoulder region of human atheroma, a frequent site of rupture characterized by elevated expression of the interstitial collagenases I (MMP-1) and III (MMP-13).5–7,10 MMP-8 exhibits 3-fold greater enzymatic activity against type I collagen than the other interstitial collagenases, which probably makes it the most efficient type I collagenolytic enzyme in humans.11–14,26
We and others previously neglected the possible role of MMP-8 in atherogenesis in light of its traditional attribution as a product of neutrophils, a cell type not commonly observed in atheroma.22 The unbiased survey afforded by transcriptional profiling pointed to a potential role of this enzyme in atherogenesis, despite its nomenclature. Our surprising finding that ECs, SMCs, and Ms within human atherosclerotic lesions express MMP-8 affirms that the expression of this interstitial collagenase extends beyond a single cell type. Recent reports suggesting expression of MMP-8 by rheumatoid synovial fibroblasts and ECs, as well as articular chondrocytes, and the observation that murine tissue not typically associated with PMN infiltration, such as kidney and muscle tissue, also expressed this enzyme support this finding.16,19,20,27 The cytokine-induced expression of MMP-8 in ECs, SMCs, and Ms differs from the release pattern in the traditional source, the neutrophil, which stores MMP-8 zymogen in granules and releases the collagenase almost immediately on stimulation.17,18 Thus, whereas MMP-8 release can occur immediately in acute inflammation associated with PMN infiltration, MMP-8 synthesis and release by ECs, SMCs, and Ms at sites of chronic inflammation, such as atheroma, requires prolonged exposure to proinflammatory cytokines. In view of the role of hypochlorous acid in MMP-8 activation, it is noteworthy that a subpopulation of Ms in advanced (but not early) atherosclerotic lesions contain myeloperoxidase, the enzyme responsible for hypochlorous acid production.17,28,29 Thus, expression of MMP-8 and its activator myeloperoxidase likely occurs contemporaneously during the differentiation of monocyte-derived Ms in vitro and in atherosclerotic lesion development in situ. Heightened expression of MMP-8 by Ms compared with monocytes agrees with previous reports on other MMPs.30,31
The localization of the 55-kDa form of MMP-8 in atheroma corresponding to the active form of the enzyme and its colocalization with cleaved rather than intact type I collagen underscore the relevance of our findings to atherosclerosis and its acute clinical sequelae, such as plaque rupture and thrombosis. Degradation of type I collagen likely leads to thinning of the fibrous cap of plaques, a characteristic of the vulnerable, rupture-prone plaque.6 Accordingly, MMP-8 concentrations in lesions prone to rupture exceed those in lesions with a more stable phenotype. Previous studies suggesting that the collagenolytic activity found at some sites of chronic inflammation, such as periodontitis, derives from MMP-8 rather than the other interstitial collagenases further support the potential relevance of this enzyme in plaque destabilization.21
The surprising finding that human vascular ECs, SMCs, and Ms express the interstitial collagenase MMP-8 in vitro on stimulation and in situ in atherosclerotic lesions not only broadens knowledge of the expression pattern of this "neutrophil collagenase" but further suggests a novel pathological role of MMP-8. Designing MMP inhibitors of restricted specificity may obviate some of the toxicity encountered in clinical trials of broad-spectrum agents. The present identification of a likely role for MMP-8 in atherogenesis thus has practical therapeutic and theoretic implications.
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Acknowledgments |
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This study was supported in part by grants from the National Heart, Lung, and Blood Institute (HL-56985) and by Millennium Pharmaceuticals, Inc. We thank Eugenia Shvartz, Anna Papautsky, and Elissa Simon-Morrissey (Brigham and Women’s Hospital) for skillful technical assistance, Karen Williams for editorial assistance, and Drs Robin Poole (McGill University) and M. Glogauer (Brigham and Women’s Hospital) for providing us with the anti-collagen antibody and PMN, respectively.
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Footnotes |
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*The first 2 authors contributed equally to this work.
Received July 6, 2001; revision received August 3, 2001; accepted August 7, 2001.
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References |
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 A. Gutierrez-Fernandez, M. Inada, M. Balbin, A. Fueyo, A. S. Pitiot, A. Astudillo, K. Hirose, M. Hirata, S. D. Shapiro, A. Noel, et al. Increased inflammation delays wound healing in mice deficient in collagenase-2 (MMP-8) FASEB J, August 1, 2007; 21(10): 2580 - 2591. [Abstract] [Full Text] [PDF]
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P. Libby Perplexity of Plaque Proteinases Arterioscler Thromb Vasc Biol, October 1, 2006; 26(10): 2181 - 2182. [Full Text] [PDF]
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K. von Wnuck Lipinski, P. Keul, N. Ferri, S. Lucke, G. Heusch, J. W. Fischer, and B. Levkau Integrin-Mediated Transcriptional Activation of Inhibitor of Apoptosis Proteins Protects Smooth Muscle Cells Against Apoptosis Induced by Degraded Collagen Circ. Res., June 23, 2006; 98(12): 1490 - 1497. [Abstract] [Full Text] [PDF]
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 A. C. Newby Matrix metalloproteinases regulate migration, proliferation, and death of vascular smooth muscle cells by degrading matrix and non-matrix substrates Cardiovasc Res, February 15, 2006; 69(3): 614 - 624. [Abstract] [Full Text] [PDF]
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C. M. Dollery and P. Libby Atherosclerosis and proteinase activation Cardiovasc Res, February 15, 2006; 69(3): 625 - 635. [Abstract] [Full Text] [PDF]
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K. von Wnuck Lipinski, P. Keul, S. Lucke, G. Heusch, J. Wohlschlaeger, H. A. Baba, and B. Levkau Degraded collagen induces calpain-mediated apoptosis and destruction of the X-chromosome-linked inhibitor of apoptosis (xIAP) in human vascular smooth muscle cells Cardiovasc Res, February 15, 2006; 69(3): 697 - 705. [Abstract] [Full Text] [PDF]
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W. R. W. Wilson, M. Anderton, E. C. Schwalbe, J. L. Jones, P. N. Furness, P. R.F. Bell, and M. M. Thompson Matrix Metalloproteinase-8 and -9 Are Increased at the Site of Abdominal Aortic Aneurysm Rupture Circulation, January 24, 2006; 113(3): 438 - 445. [Abstract] [Full Text] [PDF]
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J.-O Deguchi, E. Aikawa, P. Libby, J. R. Vachon, M. Inada, S. M. Krane, P. Whittaker, and M. Aikawa Matrix Metalloproteinase-13/Collagenase-3 Deletion Promotes Collagen Accumulation and Organization in Mouse Atherosclerotic Plaques Circulation, October 25, 2005; 112(17): 2708 - 2715. [Abstract] [Full Text] [PDF]
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 V. C. Mehra, V. S. Ramgolam, and J. R. Bender Cytokines and cardiovascular disease J. Leukoc. Biol., October 1, 2005; 78(4): 805 - 818. [Abstract] [Full Text] [PDF]
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E. Lutgens, B. Faber, K. Schapira, C. T.A. Evelo, R. van Haaften, S. Heeneman, K. B.J.M. Cleutjens, A. P. Bijnens, L. Beckers, J. G. Porter, et al. Gene Profiling in Atherosclerosis Reveals a Key Role for Small Inducible Cytokines: Validation Using a Novel Monocyte Chemoattractant Protein Monoclonal Antibody Circulation, June 28, 2005; 111(25): 3443 - 3452. [Abstract] [Full Text] [PDF]
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U. Bavendiek, A. Zirlik, S. LaClair, L. MacFarlane, P. Libby, and U. Schonbeck Atherogenesis in Mice Does Not Require CD40 Ligand From Bone Marrow-Derived Cells Arterioscler Thromb Vasc Biol, June 1, 2005; 25(6): 1244 - 1249. [Abstract] [Full Text] [PDF]
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A. Garcia-Touchard, T. D. Henry, G. Sangiorgi, L. G. Spagnoli, A. Mauriello, C. Conover, and R. S. Schwartz Extracellular Proteases in Atherosclerosis and Restenosis Arterioscler Thromb Vasc Biol, June 1, 2005; 25(6): 1119 - 1127. [Abstract] [Full Text] [PDF]
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 N. P. Kadoglou, S. S. Daskalopoulou, D. Perrea, and C. D. Liapis Matrix Metalloproteinases and Diabetic Vascular Complications Angiology, March 1, 2005; 56(2): 173 - 189. [Abstract] [PDF]
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A. C. Newby Dual Role of Matrix Metalloproteinases (Matrixins) in Intimal Thickening and Atherosclerotic Plaque Rupture Physiol Rev, January 1, 2005; 85(1): 1 - 31. [Abstract] [Full Text] [PDF]
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 H. Wang, S. Parry, G. Macones, M. D. Sammel, P. E. Ferrand, H. Kuivaniemi, G. Tromp, I. Halder, M. D. Shriver, R. Romero, et al. Functionally significant SNP MMP8 promoter haplotypes and preterm premature rupture of membranes (PPROM) Hum. Mol. Genet., November 1, 2004; 13(21): 2659 - 2669. [Abstract] [Full Text] [PDF]
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Y. Fukumoto, J.-o Deguchi, P. Libby, E. Rabkin-Aikawa, Y. Sakata, M. T. Chin, C. C. Hill, P. R. Lawler, N. Varo, F. J. Schoen, et al. Genetically Determined Resistance to Collagenase Action Augments Interstitial Collagen Accumulation in Atherosclerotic Plaques Circulation, October 5, 2004; 110(14): 1953 - 1959. [Abstract] [Full Text] [PDF]
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C. Whatling, H. Bjork, S. Gredmark, A. Hamsten, and P. Eriksson Effect of macrophage differentiation and exposure to mildly oxidized LDL on the proteolytic repertoire of THP-1 monocytes J. Lipid Res., September 1, 2004; 45(9): 1768 - 1776. [Abstract] [Full Text] [PDF]
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N. Kalinina, A. Agrotis, Y. Antropova, O. Ilyinskaya, V. Smirnov, E. Tararak, and A. Bobik Smad Expression in Human Atherosclerotic Lesions: Evidence for Impaired TGF-{beta}/Smad Signaling in Smooth Muscle Cells of Fibrofatty Lesions Arterioscler Thromb Vasc Biol, August 1, 2004; 24(8): 1391 - 1396. [Abstract] [Full Text] [PDF]
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Z. S. Galis Vulnerable Plaque: The Devil Is in the Details Circulation, July 20, 2004; 110(3): 244 - 246. [Full Text] [PDF]
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K.J. Molloy, M.M. Thompson, J.L. Jones, E.C. Schwalbe, P.R.F. Bell, A.R. Naylor, and I.M. Loftus Unstable Carotid Plaques Exhibit Raised Matrix Metalloproteinase-8 Activity Circulation, July 20, 2004; 110(3): 337 - 343. [Abstract] [Full Text] [PDF]
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 C. A. Owen, Z. Hu, C. Lopez-Otin, and S. D. Shapiro Membrane-Bound Matrix Metalloproteinase-8 on Activated Polymorphonuclear Cells Is a Potent, Tissue Inhibitor of Metalloproteinase-Resistant Collagenase and Serpinase J. Immunol., June 15, 2004; 172(12): 7791 - 7803. [Abstract] [Full Text] [PDF]
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U. Schonbeck and P. Libby Inflammation, Immunity, and HMG-CoA Reductase Inhibitors: Statins as Antiinflammatory Agents? Circulation, June 1, 2004; 109(21_suppl_1): II-18 - II-26. [Abstract] [Full Text] [PDF]
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 S. Apajalahti, T. Sorsa, S. Railavo, and T. Ingman The in vivo Levels of Matrix Metalloproteinase-1 and -8 in Gingival Crevicular Fluid during Initial Orthodontic Tooth Movement Journal of Dental Research, December 1, 2003; 82(12): 1018 - 1022. [Abstract] [Full Text] [PDF]
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E. Lutgens, R.-J. van Suylen, B. C. Faber, M. J. Gijbels, P. M. Eurlings, A.-P. Bijnens, K. B. Cleutjens, S. Heeneman, and M. J.A.P. Daemen Atherosclerotic Plaque Rupture: Local or Systemic Process? Arterioscler Thromb Vasc Biol, December 1, 2003; 23(12): 2123 - 2130. [Abstract] [Full Text] [PDF]
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O. D Defawe, A. Colige, C. A Lambert, C. Munaut, P. Delvenne, C. M Lapiere, R. Limet, B. V Nusgens, and N. Sakalihasan TIMP-2 and PAI-1 mRNA levels are lower in aneurysmal as compared to athero-occlusive abdominal aortas Cardiovasc Res, October 15, 2003; 60(1): 205 - 213. [Abstract] [Full Text] [PDF]
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C. B Jones, D. C Sane, and D. M Herrington Matrix metalloproteinases: A review of their structure and role in acute coronary syndrome Cardiovasc Res, October 1, 2003; 59(4): 812 - 823. [Abstract] [Full Text] [PDF]
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C. M. Dollery, C. A. Owen, G. K. Sukhova, A. Krettek, S. D. Shapiro, and P. Libby Neutrophil Elastase in Human Atherosclerotic Plaques: Production by Macrophages Circulation, June 10, 2003; 107(22): 2829 - 2836. [Abstract] [Full Text] [PDF]
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S. Blankenberg, H. J. Rupprecht, O. Poirier, C. Bickel, M. Smieja, G. Hafner, J. Meyer, F. Cambien, L. Tiret, and for the AtheroGene Investigators Plasma Concentrations and Genetic Variation of Matrix Metalloproteinase 9 and Prognosis of Patients With Cardiovascular Disease Circulation, April 1, 2003; 107(12): 1579 - 1585. [Abstract] [Full Text] [PDF]
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M. W. Manning, L. A. Cassis, and A. Daugherty Differential Effects of Doxycycline, a Broad-Spectrum Matrix Metalloproteinase Inhibitor, on Angiotensin II-Induced Atherosclerosis and Abdominal Aortic Aneurysms Arterioscler Thromb Vasc Biol, March 1, 2003; 23(3): 483 - 488. [Abstract] [Full Text] [PDF]
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 P. K. Shah Mechanisms of plaque vulnerability and rupture J. Am. Coll. Cardiol., February 19, 2003; 41(4_Suppl_S): 15S - 22S. [Abstract] [Full Text] [PDF]
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 E. Mueller, S. Drori, A. Aiyer, J. Yie, P. Sarraf, H. Chen, S. Hauser, E. D. Rosen, K. Ge, R. G. Roeder, et al. Genetic Analysis of Adipogenesis through Peroxisome Proliferator-activated Receptor gamma Isoforms J. Biol. Chem., October 25, 2002; 277(44): 41925 - 41930. [Abstract] [Full Text] [PDF]
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G. K. Sukhova, J. K. Williams, and P. Libby Statins Reduce Inflammation in Atheroma of Nonhuman Primates Independent of Effects on Serum Cholesterol Arterioscler Thromb Vasc Biol, September 1, 2002; 22(9): 1452 - 1458. [Abstract] [Full Text] [PDF]
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P. Libby and M. Aikawa Vitamin C, Collagen, and Cracks in the Plaque Circulation, March 26, 2002; 105(12): 1396 - 1398. [Full Text] [PDF]
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U. Schonbeck and P. Libby CD40 Signaling and Plaque Instability Circ. Res., December 7, 2001; 89(12): 1092 - 1103. [Abstract] [Full Text] [PDF]
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P. K. Shah and Z. S. Galis Matrix Metalloproteinase Hypothesis of Plaque Rupture: Players Keep Piling Up But Questions Remain Circulation, October 16, 2001; 104(16): 1878 - 1880. [Full Text] [PDF]
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