Masanori Aikawa, MD, PhD Peter Libby, MD

1
The balance of power in vulnerable plaques
collagenases vs. collagen
Masanori Aikawa, MD, PhD Peter Libby,
MD Cardiovascular Medicine Brigham and Womens
Hospital Harvard Medical School Boston, MA
2
Abstract
Rupture 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.
3
Rupture of the vulnerable atherosclerotic
plaque triggers acute coronary syndromes
Thrombus
Thin Fibrous Cap
Lipid Core
M.L. Higuchi
4
Characterization of the vulnerable
atherosclerotic plaque
More stable plaque
Thin fibrous cap Collagen-poor
Lumen
Atheromatous core Lipid, Macrophage-rich Proteolyt
ic activity (MMPs) Prothrombotic activity (TF)
Adopted from Masanori Aikawa and Peter Libby,
European Heart Journal 2001
5
Collagen breakdown by collagenases may contribute
to the vulnerability of atheroma
6
Major statin trials
Lipid lowering by HMG-CoA reductase inhibitors
reduces the incidence of acute coronary events
probably by stabilization of vulnerable
atherosclerotic plaques
Primary prevention
Secondary prevention
WOSCOPS
4S
Simvastatin 34 risk reduction
Pravastatin 31 risk reduction
Cholesterol levels Average High
CARE
AFCAPS/TexCAPS
Pravastatin 24 risk reduction
Lovastatin 40 risk reduction
LIPID
Pravastatin 24 risk reduction
From Gotto and Farmer in Heart Disease
(Braunwald, Zipes, Libby), 6th ed., 2001
7
Stabilization of vulnerable plaques by lipid
lowering
Stabilization
Thin fibrous cap Collagen-poor Activated SMC
(MMP, TF)
Activated EC VCAM-1, MCP-1
Qualitative or functional changes
Macrophages MMPs, TF Collagen
Lumen
?
Regression
Quantitative changes Lesion size
Luminal area Inward remodeling?
Atheromatous core Macrophage-rich Proteolytic
activity (MMP) Prothrombotic activity (TF)
Masanori Aikawa and Peter Libby, European Heart
Journal 2001
8
Hypothesis 1
Do human and experimental atherosclerotic plaques
contain collagenases?
9
Hypothesis 2
Does lipid lowering improve features associated
with plaque vulnerability (i.e, macrophage
accumulation, collagenase expression, collagen
content)?
10
Hypothesis 3
Does collagenolysis regulate collagen
accumulation of atheroma in genetically-altered
mice?
11
Macrophage expression of collagenases in human
atheroma
MMP-1 / Collagenase-1
MMP-13 / Collagenase-3
Macrophages
Sukhova GK, et al. Circulation 2000
Galis ZS, et al. JCI 1994
12
Cell-type
MMP-8
MMP-8/collagenase-2 expression by all cell types
in human atheroma Herman et al. Circulation 2001
EC
SMC
MØ
13
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 1998972433-2444
14
MMP-13/collagenase-3 expression by macrophages in
atheroma of apoE-deficient mice
Macrophages
MMP-13 / collagenase-3
Fukumoto, Libby, Rabkin, Deguchi, Varo, Harada,
Hill, Lawler, Schoen, Krane, Aikawa. Unpublished
data.
15
MMP-3 and MMP-9 expression in atheroma of
Watanabe heritable hyperlipidemic (WHHL) rabbits
MMP-3/stromelysin-1
MMP-9/gelatinase-B
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin,
Christopher C. Hill, Makoto Enomoto, Yasuhiko
Hirouchi, Masashi Shiomi, Masanori Aikawa
Circulation 2001103993-999
16
Decreased collagenase and increased collagen
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 1998972433-2444
17
Dietary lipid lowering reduces macrophages in
atheroma of cholesterol-fed rabbits
After lipid lowering
Baseline lesion
Masanori Aikawa, Elena Rabkin, Yoshikatsu Okada,
Sami Voglic, Steven Clinton, Constance
Brinckerhoff, Galina Sukhova, Peter Libby
Circulation 1998972433-2444
18
Collagen (Sirius red)
Collagenase-1/MMP-1
Dietary lipid lowering reduces collagenase
expression and increases collagen accumulation
in atheroma of cholesterol-fed rabbits
Collagen
Baseline lesion
Masanori Aikawa, Elena Rabkin, Yoshikatsu Okada,
Sami J. Voglic, Steven K. Clinton, Constance E.
Brinckerhoff, Galina K. Sukhova, Peter Libby
Circulation 1998972433-2444
After Lipid Lowering
19
Diet lipid lowering promotes accumulation of
mature SMCs expressing less MMPs in atheroma of
cholesterol-fed rabbits
Masanori Aikawa, Elena Rabkin, Sami J. Voglic,
Helen Shing, Ryozo Nagai, Frederick J. Schoen,
Peter Libby Circulation Research
1998831015-1026
20
Plaque Stabilization by Statins 1 Effects on
Evolution of Atheroma
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 Libby Circulation 2001103276-283
21
Plaque Stabilization by Statins 1 Effects on
Evolution of Atheroma
Cerivastatin treatment reduces MMP expression by
macrophages in atheroma of WHHL rabbits
MMP-1/collagenase-1
MMP-9/gelatinase-B
MMP-3/stromelysin-1
Masanori Aikawa, Elena Rabkin, Seigo Sugiyama,
Sami Voglic, Yoshihiro Fukumoto, Yutaka Furukawa,
Masashi Shiomi, Frederick J. Schoen, Peter Libby
Circulation 2001103276-283
22
Plaque Stabilization by Statins 1 Effects on
Evolution of Atheroma
Cerivastatin increases interstitial collagen
accumulation in atheroma of WHHL rabbits
Picrosirius red polarization
Masanori Aikawa, Elena Rabkin, Seigo Sugiyama,
Sami J. Voglic, Yoshihiro Fukumoto, Yutaka
Furukawa, Masashi Shiomi, Frederick J. Schoen,
Peter Libby Circulation 2001103276-283
23
Plaque Stabilization by Statins 2 Differential
Effects of Statins
Pravastatin (hydrophilic) and fluvastatin
(lipophilic) reduce MMP in macrophages in
atheroma of WHHL rabbits to a similar extent
MMP-3 () M?
MMP-9 () M?
MMP-1 () M?


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100
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100
50
50
50
0
0
0
Cont n10
Prava n9
Fluva n10
Cont n10
Prava n9
Fluva n10
Cont n10
Prava n9
Fluva n10
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin,
Christopher C. Hill, Makoto Enomoto, Yasuhiko
Hirouchi, Masashi Shiomi, Masanori Aikawa
Circulation 2001103993-999
24
Plaque Stabilization by Statins 2 Differential
Effects of Statins
Atheroma of pravastatin -treated WHHL rabbits
contain more interstitial collagen than those
treated with fluvastatin
Picrosirius Red Polarization
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin,
Christopher C. Hill, Makoto Enomoto, Yasuhiko
Hirouchi, Masashi Shiomi, Masanori Aikawa
Circulation 2001103993-999
25
Pravastatin-treated WHHL rabbits contain more
procollagen-I mRNA expression than those with
fluvastatin treatment
Pravastatin
Fluvastatin
Procollagen-I mRNA
SMa-actin
Yoshihiro Fukumoto, Peter Libby, Elena Rabkin,
Christopher C. Hill, Makoto Enomoto, Yasuhiko
Hirouchi, Masashi Shiomi, Masanori Aikawa
Circulation 2001103993-999
26
Lipid lowering in rabbit atheroma
Diet Statins Lesion size...Decr
eased No change Macrophage accumulation..Decr
eased Decreased Macrophage proliferation.
Decreased Macrophage apoptosis. No
change MMP expression/activity..Decreased De
creased Collagen accumulation.Increased Inc
reased Tissue factor expression/activity...Decre
ased Decreased PAI-1 expression. Decre
ased CD154 (CD40L) expression..Decreased Decr
eased PDGF-B expressionDecreased SMC
differentiation.Increased
27
Lipid lowering in rabbit atheroma
Diet Statins apoB-100 accumulationD
ecreased MDA accumulation.Decreased Decre
ased ROS production..Decreased VCAM-1
expression...Decreased MCP-1
expression..Decreased eNOS
expression...Increased Microvessels.
..Decreased
Aikawa M, et al. Circulation
1998972433-2444, Circ Res 1998831015-1026,
Circulation 19991001215-1222, Circulation
2001103276-283, Circulation in
revision Fukumoto Y, et al. Circulation
2001103993-999, Circulation in
revision McConnell M, et al. Arterioscler Thromb
Vasc Biol 1999191956-1959
28
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.
MMP-collagenases (MMP-1, MMP-13)
?
Collagen accumulation
29
In vivo direct evidence of the role of collagenase
Genetically-determined resistance to collagenase
action alters content of collagen and smooth
muscle cells in atheroma
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
Brigham and Womens Hospital, Massachusetts
General Hospital, Harvard Medical School,
Boston, MA
ACC2002 Young Investigator Awards Molecular and
Cellular Cardiology Monday, March 18, 2 PM
Georgia World Congress Center, Room 257W
30
Collagenase-resistant mutant knock-in mouse
Fibrillar collagen
MMP-1 / collagenase-1
Mutation at specific cleavage Site of type-I
collagen for MMP-collagenases
MMP-8 / collagenase-2
MMP-13 / collagenase-3
MMP-13 / collagenase-3
MMP-2 / gelatinase-A
MMP-9 / gelatinase-B
31
Does collagenase-resistance preserve more
collagen in mouse atheroma ?
Col/ / apoE-/-
ColR/R / apoE-/-
?
32
Conclusion
Collagenases play a critical role in collagen
metabolism in atheroma.
33
Acknowledgment
Brigham and Womens Hospital, Boston Yoshihiro
Fukumoto Elena Rabkin Christopher C. Hill Sami
J. Voglic Seigo Sugiyama Jun-o Deguchi Koichiro
Harada Nerea Varo Patrick Lawler
MGH, Boston Steve M, Krane Univ. of Tokyo Ryozo
Nagai Kobe Univ. Masashi Shiomi USC, LA Alex
Sevanian
Yoshikatsu Okada Yutaka Furukawa Eugenia
Shvartz Helen Shing Galina K. Sukhova Michael
Herman Uwe Schoenbeck Frederick J. Schoen