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Masanori Aikawa, MD, PhD Peter Libby, MD
Cardiovascular Medicine Brigham and Women’s Hospital
Harvard Medical SchoolBoston, MA
The balance of power in “vulnerable” plaques: collagenases vs. collagen
AbstractRupture of the “vulnerable” plaque often triggers acute coronary syndromes.Interstitial collagen determines plaque stability.We have demonstrated macrophage expression of collagenases (MMP-1, MMP-8 and MMP-13) in human and experimental atherosclerosis.Collagen degradation by collagenases may contribute to the vulnerability of atheroma.
Lipid lowering in hypercholesterolemic rabbits reduces collagenase expression and ,in parallel, increases collagen in atheroma, suggesting a critical role of collagenase in collagen balance.We have recently found that collagenase-resistance alters collagen content in mouse atheroma.These results suggest that collagenase action regulates the collagen metabolism crucial to the clinical complications of atheroma.
M.L. Higuchi
ThrombusThrombus
Thin Thin Fibrous Fibrous CapCap
Lipid CoreLipid Core
Rupture of the “vulnerable” atherosclerotic Rupture of the “vulnerable” atherosclerotic plaque triggers acute coronary syndromes plaque triggers acute coronary syndromes
Atheromatous coreLipid, Macrophage-richProteolytic activity (MMPs) Prothrombotic activity (TF)
Characterization of the “vulnerable” atherosclerotic plaque
Lumen
More stable plaque
Adopted from Masanori Aikawa and Peter Libby, European Heart Journal 2001
Lumen
Thin fibrous capCollagen-poor
Degradadation fragments (3/4 & 1/4)
Small peptides / Amino Acids
Fibrillar collagen
MMP-13 / collagenase-3MMP-8 / collagenase-2MMP-1 / collagenase-1
MMP-13 / collagenase-3MMP-2 / gelatinase-AMMP-9 / gelatinase-B
Collagen breakdown by collagenases may contribute to the vulnerability of atheroma
Lipid lowering by HMG-CoA reductase inhibitors reduces the incidence of acute coronary events probably by stabilization of “vulnerable” atherosclerotic plaques
Major statin trialsCh
oles
tero
l lev
els
Ave
rage
High
Primary prevention Secondary prevention
WOSCOPS 4S
AFCAPS/TexCAPSCARE
Pravastatin24% risk reduction
Simvastatin34% risk reduction
Lovastatin40% risk reduction
Pravastatin31% risk reduction
LIPIDPravastatin
24% risk reduction
From Gotto and Farmer in Heart Disease (Braunwald, Zipes, Libby), 6th ed., 2001
Quantitative changes Lesion size Luminal area Inward remodeling?
??Atheromatous coreMacrophage-richProteolytic activity (MMP) Prothrombotic activity (TF)
Thin fibrous capCollagen-poorActivated SMC (MMP, TF)
Stabilization of “vulnerable” plaques by lipid lowering
Lumen
“Regression”
“Stabilization”Activated ECVCAM-1, MCP-1
Masanori Aikawa and Peter Libby, European Heart Journal 2001
Qualitative or functional changes Macrophages MMPs, TF Collagen
Hypothesis 1
Do human and experimental atherosclerotic plaques contain collagenases?
Hypothesis 2Does lipid lowering improve features associated with plaque vulnerability: (i.e, macrophage accumulation, collagenase expression, collagen content)?
Hypothesis 3Does collagenolysis regulate collagen accumulation of atheroma in genetically-altered mice?
Macrophage expression of collagenases in human atheroma
Galis ZS, et al. JCI 1994 Sukhova GK, et al. Circulation 2000
MMP-1 / Collagenase-1 MMP-13 / Collagenase-3
Macrophages
Cell-typeMMP-8
EC
SMC
MØ
MMP-8/collagenase-2 expression by all cell types in human atheromaHerman et al.
Circulation 2001
MMP-1/collagenase-1 expression in atheroma of cholesterol-fed rabbits
Smooth muscle cells Macrophages MMP-1/collagenase-1
Masanori Aikawa, Elena Rabkin, Yoshikatsu Okada, Sami Voglic, Steven Clinton, Constance Brinckerhoff, Galina Sukhova, Peter Libby Circulation 1998;97:2433-2444
MMP-13/collagenase-3 expression by macrophages in atheroma
of apoE-deficient miceMacrophagesMacrophages MMP-13 / collagenase-3MMP-13 / collagenase-3
Fukumoto, Libby, Rabkin, Deguchi, Varo, Harada, Hill, Lawler, Schoen, Krane, Aikawa. Unpublished data.
MMP-3/stromelysin-1 MMP-9/gelatinase-B
MMP-3 and MMP-9 expression in atheroma of Watanabe heritable hyperlipidemic
(WHHL) rabbits
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin, Christopher C. Hill, Makoto Enomoto, Yasuhiko Hirouchi, Masashi Shiomi,
Masanori Aikawa Circulation 2001;103:993-999
Dietary lipid lowering reduces macrophages, MMP expression, and increases collagen content(a key determinant of plaque stability) in atheroma of cholesterol-fed rabbits Masanori Aikawa, Elena Rabkin, Yoshikatsu Okada, Sami J. Voglic, Steven K. Clinton, Constance E. Brinckerhoff, Galina K. Sukhova, Peter Libby Circulation 1998;97:2433-2444
Decreased collagenase and increased collagen
Dietary lipid lowering reduces macrophagesin atheroma of cholesterol-fed rabbits
Baseline lesion After lipid lowering
Masanori Aikawa, Elena Rabkin,Yoshikatsu Okada, Sami Voglic,Steven Clinton, Constance Brinckerhoff,Galina Sukhova, Peter Libby Circulation 1998;97:2433-2444
Collagen (Sirius red)
Masanori Aikawa,Elena Rabkin,Yoshikatsu Okada, Sami J. Voglic,Steven K. Clinton,Constance E. Brinckerhoff,Galina K. Sukhova,Peter Libby
Circulation 1998;97:2433-2444
Dietary lipid loweringreduces collagenase expression and increases collagenaccumulation in atheroma of cholesterol-fed rabbits
Baseline lesion
Collagenase-1/MMP-1 Collagen
After Lipid Lowering
Diet lipid lowering promotes accumulation of mature SMCs expressing less MMPsin atheroma of cholesterol-fed rabbits
Masanori Aikawa, Elena Rabkin, Sami J. Voglic, Helen Shing, Ryozo Nagai, Frederick J. Schoen, Peter LibbyCirculation Research 1998;83:1015-1026
Control GroupControl Group
MM MMP-1MMP-1
MM MMP-1MMP-1
Cerivastatin GroupCerivastatin Group
Cerivastatin reduces macrophage accumulation and MMP expression in atheroma of WHHL rabbits
Masanori Aikawa, Elena Rabkin, Seigo Sugiyama, Sami J. Voglic, Yoshihiro Fukumoto, Yutaka Furukawa, Masashi Shiomi, Frederick J. Schoen, Peter LibbyCirculation 2001;103:276-283
Plaque Stabilization by Statins 1Effects on Evolution of Atheroma
Cerivastatin treatment reduces MMP expression by macrophages in atheroma of WHHL rabbits MMP-1/collagenase-1 MMP-9/gelatinase-BMMP-3/stromelysin-1
Masanori Aikawa, Elena Rabkin, Seigo Sugiyama, Sami Voglic, Yoshihiro Fukumoto, Yutaka Furukawa, Masashi Shiomi, Frederick J. Schoen, Peter Libby Circulation 2001;103:276-283
CerivastatinControl0
10
20
30
40
50 p<0.01
0
20
40
60
80
CerivastatinControl0
10
20
30
40 p<0.01
CerivastatinControl
p<0.01
MM
P-po
sitiv
e m
acro
phag
es (%
)
n=9 n=10 n=9 n=10n=9 n=10
Plaque Stabilization by Statins 1Effects on Evolution of Atheroma
CerivastatinCerivastatin
ControlControlCerivastatin increasesinterstitial collagen accumulationin atheroma of WHHL rabbitsPicrosirius red polarizationPicrosirius red polarizationMasanori Aikawa, Elena Rabkin, Seigo Sugiyama, Sami J. Voglic, Yoshihiro Fukumoto, Yutaka Furukawa, Masashi Shiomi, Frederick J. Schoen, Peter Libby
Circulation 2001;103:276-283
Plaque Stabilization by Statins 1Effects on Evolution of Atheroma
Pravastatin (hydrophilic) and fluvastatin (lipophilic) reduce MMP in macrophages in atheroma of WHHL rabbits t
o a similar extentMMP-1 (+) M
100
Contn=10
Pravan=9
Fluvan=10
0
50
%p<0.01
MMP-3 (+) M
Contn=10
Pravan=9
Fluvan=10
0
50
100%
p<0.05p<0.05
100
MMP-9 (+) M
Contn=10
Pravan=9
Fluvan=10
0
50
%p<0.01
p<0.01
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin, Christopher C. Hill, Makoto Enomoto, Yasuhiko Hirouchi, Masashi Shiomi, Masanori Aikawa Circulation 2001;103:993-999
Plaque Stabilization by Statins 2Differential Effects of Statins
Picrosirius Red Polarization
Atheroma of pravastatin -treated WHHL rabbits contain more interstitial collagen than those treated with fluvastatin
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin, Christopher C. Hill, Makoto Enomoto, Yasuhiko Hirouchi, Masashi Shiomi, Masanori Aikawa Circulation 2001;103:993-999
Control
Pravastatin
FluvastatinContn=10
Pravan=9
Fluvan=10
05
1015 p<0.01 p<0.01
%-p
ositi
ve a
rea
Plaque Stabilization by Statins 2Differential Effects of Statins
Pravastatin Fluvastatin
Procollagen-I mRNA
SM-actin
Pravastatin-treated WHHL rabbits contain more procollagen-I mRNA expression than those
with fluvastatin treatment
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin, Christopher C. Hill, Makoto Enomoto, Yasuhiko Hirouchi, Masashi Shiomi, Masanori Aikawa Circulation 2001;103:993-999
Diet StatinsLesion size………………………………...Decreased No changeMacrophage accumulation……………..Decreased Decreased Macrophage proliferation………………. Decreased Macrophage apoptosis…………………. No changeMMP expression/activity………………..Decreased DecreasedCollagen accumulation………………….Increased IncreasedTissue factor expression/activity……...Decreased DecreasedPAI-1 expression…………………………. DecreasedCD154 (CD40L) expression……………..Decreased DecreasedPDGF-B expression………………………DecreasedSMC differentiation……………………….Increased
Lipid lowering in rabbit atheroma
Lipid lowering in rabbit atheromaDiet Statins
apoB-100 accumulation…………………DecreasedMDA accumulation……………………….Decreased DecreasedROS production…………………………..DecreasedVCAM-1 expression……………………...DecreasedMCP-1 expression………………………..DecreasedeNOS expression………………………...IncreasedMicrovessels.……………………………..Decreased
Aikawa M, et al. Circulation 1998;97:2433-2444, Circ Res 1998;83:1015-1026, Circulation 1999;100:1215-1222, Circulation 2001;103:276-283, Circulation in revision
Fukumoto Y, et al. Circulation 2001;103:993-999, Circulation in revisionMcConnell M, et al. Arterioscler Thromb Vasc Biol 1999;19:1956-1959
Collagen accumulation
MMP-collagenases (MMP-1, MMP-13)
Inverse relationship between collagenase expression and collagen content in atheroma during lipid lowering suggests the crucial role of collagenase in collagen balance. However, no direct evidence links collagenases with regulation of the collagen content of atheroma.
??
“Genetically-determined resistance to collagenase action alters content of collagen and smooth
muscle cells in atheroma”
Brigham and Women’s Hospital, Massachusetts General Hospital, Harvard Medical School, Boston, MA
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin, Jun-o Deguchi, Nerea Varo, Koichiro Harada, Christopher C. Hill, Patrick R. Lawler,
Frederick J. Schoen, Stephen M. Krane, Masanori Aikawa
ACC2002 Young Investigator AwardsMolecular and Cellular Cardiology
Monday, March 18, 2 PM Monday, March 18, 2 PM Georgia World Congress Center, Room 257W
In vivo direct evidence of the role of collagenase
Fibrillar collagen
MMP-13 / collagenase-3MMP-8 / collagenase-2MMP-1 / collagenase-1
MMP-13 / collagenase-3MMP-2 / gelatinase-AMMP-9 / gelatinase-B
Collagenase-resistant mutant “knock-in” mouse
Mutation at specific cleavageSite of type-I collagen for MMP-collagenases
Does collagenase-resistance preserve more collagen in mouse atheroma ?
Col+/+ / apoE-/- ColR/R / apoE-/-
??
Conclusion
Collagenases play a critical role in collagen metabolism in atheroma.
AcknowledgmentBrigham and Women’s Hospital, BostonYoshihiro Fukumoto Elena Rabkin Christopher C. HillSami J. VoglicSeigo SugiyamaJun-o DeguchiKoichiro HaradaNerea VaroPatrick Lawler
MGH, BostonSteve M, Krane
Univ. of TokyoRyozo NagaiKobe Univ.Masashi ShiomiUSC, LAAlex Sevanian
Yoshikatsu OkadaYutaka FurukawaEugenia ShvartzHelen Shing Galina K. SukhovaMichael HermanUwe SchoenbeckFrederick J. Schoen
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