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Ebt calcium score a clue to invulnerable plaque in vulnerable patients
1. EBT Calcium Score:EBT Calcium Score:
A Clue to Invulnerable PlaquesA Clue to Invulnerable Plaques
In Vulnerable PatientsIn Vulnerable Patients
John A. Rumberger, PhD, MD, FACCJohn A. Rumberger, PhD, MD, FACC
Clinical Professor of Medicine, Ohio State UniversityClinical Professor of Medicine, Ohio State University
Medical Director, OhioHeartMedical Director, OhioHeart
Columbus, OhioColumbus, Ohio
The 3rd
Vulnerable Plaque Symposium
51st
Annual ACC, Atlanta GA, 3/16/02
2. Electron Beam TomographyElectron Beam Tomography
[EBT][EBT]
Is a unique and established tomographic scanning methodIs a unique and established tomographic scanning method
[1[1stst
introduced in 1984] using a scanning electron beamintroduced in 1984] using a scanning electron beam
rather than a rotating X-ray source [e.g. helical CT]rather than a rotating X-ray source [e.g. helical CT]
Rapidly images the patient’s heart [50 or 100 msec/image,Rapidly images the patient’s heart [50 or 100 msec/image,
Approximately 10 times faster than helical CT]Approximately 10 times faster than helical CT]
Imaging done synchronized at a phase of the cardiacImaging done synchronized at a phase of the cardiac
cycle corresponding to the least ballistic coronary motioncycle corresponding to the least ballistic coronary motion
3. Electron Beam TomographyElectron Beam Tomography
Over the past 18 years there have > 600Over the past 18 years there have > 600
scientificscientific
papers published regarding EBT validationpapers published regarding EBT validation
andand
applications for cardiac imagingapplications for cardiac imaging
However, theHowever, the applicationapplication receiving the mostreceiving the most
““notice” (and controversy) has been its abilitynotice” (and controversy) has been its ability
4. Coronary Artery CalcificationCoronary Artery Calcification
““Hardening”Hardening” of the coronary arteries has known
for 300 years; but over the pastthe past 10 years10 years we havewe have
found it is:found it is:
An ActiveAn Active ((notnot passive)passive) processprocess
CanCan OccurOccur earlyearly in ASO plaque developmentin ASO plaque development
AnAn Intimate part ofIntimate part of the fibroproliferative andthe fibroproliferative and
inflammatory pathophysiology of CADinflammatory pathophysiology of CAD
RegulatedRegulated in a fashion similar to bonein a fashion similar to bone
mineralization and repairmineralization and repair
6. Metabolic Dyslipidemia
in Insulin Resistant States
Pathobiology & Molecular Mechanisms
Khosrow Adeli Ph.D., FCACB, DABCC, NACB
Head & Professor, Clinical Biochemistry
Laboratory Medicine and Pathobiology
Hospital for Sick Children
University of Toronto
Toronto, CANADA
7. Summary of PresentationSummary of Presentation
Introduction:Introduction:
Insulin Resistance/Metabolic DyslipidemiaInsulin Resistance/Metabolic Dyslipidemia
Recent ObservationsRecent Observations
Animal Model of Insulin ResistanceAnimal Model of Insulin Resistance
(Fructose-Fed Syrian Golden Hamster)
• Evidence for Hepatic VLDL Overproduction
• Evidence for Hepatic Insulin Resistance
• Evidence for Intestinal Lipoprotein Overproduction
8. The diverse biological manifestations of the insulin
resistant state arise as a consequence of both
a blunted insulin action as well as the compensatory
hyperinsulinemia per se.
Insulin Resistance
Insulin resistant
peripheral tissues
Insulin
Increased insulin action
in more sensitive tissues
or biochemical pathwaysPancreas
9. Clinical spectrum of
insulin resistant states
• Rare (genetic) forms of insulin resistance
• Obesity (central, abdominal, visceral,
android)
• Fasting hyperglycemia/Impaired glucose
tolerance
• Type 2 diabetes mellitus
12. Features of Metabolic Dyslipidemia
•• HypertriglyceridemiaHypertriglyceridemia
TG,TG, ApoBApoB
VLDL-TG and VLDL-apoB secretionVLDL-TG and VLDL-apoB secretion
Small Dense LDLSmall Dense LDL
( LDL particle density)( LDL particle density)
•• Reduced HDL-CReduced HDL-C
•• Increase FFAIncrease FFA
13. FFA
FA
VLDL
DNL
Adipose tissue
Muscle
Liver
Intestine
TG mobilization
by tissue lipases
TG, CE
ApoB
Cytosolic TG
stores
Oxidation
Lipases
LPL
Mechanisms of VLDL overproductionMechanisms of VLDL overproduction
in Insulin Resistancein Insulin Resistance
Hepatic
Insulin Resistance
Adeli K. et al. (2000) J. Biol. Chem. 275: 8416-8425.
Adeli K. et al. (2002) J. Biol. Chem. 277:793-803.
14. VLDL
ApoB mRNA Translation
Degradation
ER
Membrane
5' 3'
ApoB mRNA
VLDL Assembly
Degradation
Secretion
MTP
Proteasome
Hepatic Synthesis and Secretion of VLDLHepatic Synthesis and Secretion of VLDL
Lipid Poor State
Lipid Rich State
Lipid Poor State
ApoB Gene Expression
VLDL
Plasma
Hepatocy
te
CE
PL
TG
C
15. Mechanisms of VLDL OverproductionMechanisms of VLDL Overproduction
in Insulin Resistance (Recent Progress)in Insulin Resistance (Recent Progress)
• Development of a Fructose-Fed Hamster Model of
Insulin Resistance
• Investigations into Mechanisms of Hepatic VLDL
Overproduction
• Investigations into Mechanisms of Intestinal
Lipoprotein Overproduction
• Assessment of the Efficacy of hypolipidemic
agents and insulin sensitizers in ameliorating
metabolic dyslipidemia
16. Insulin Resistance Model
Fructose-Fed Syrian Golden Hamster
• Lipoprotein metabolism closely resembles that in
humans
• Hamster liver secretes VLDL containing only
apoB100 with a density close to that of human VLDL
• Hamsters develop hyperTG, hyperCHOL, &
atherosclerosis in response to a modest increase in
dietary cholesterol & saturated fat
• Hamster can be made Obese, Hypertriglyceridemic,
Hyperinsulinemic, and Insulin Resistant by
carbohydrate feeding (particularly Fructose)
17. Male Syrian Golden Hamsters (80-100 grams)Male Syrian Golden Hamsters (80-100 grams)
60% Fructose Diet60% Fructose Diet
(2 weeks)(2 weeks)
Control HamstersControl Hamsters
Control DietControl Diet
(2 weeks)(2 weeks)
Fructose-fed HamstersFructose-fed Hamsters
Plasma Analysis: Glucose, TG, Chol, InsulinPlasma Analysis: Glucose, TG, Chol, Insulin
Liver Perfusions >>>>>>Primary HepatocytesLiver Perfusions >>>>>>Primary Hepatocytes
Intestinal Fragments >>>>>>Primary EnterocytesIntestinal Fragments >>>>>>Primary Enterocytes
Experiments on Hepatic & Intestinal LipoproteinsExperiments on Hepatic & Intestinal Lipoproteins
Plasma Glucose, TG, Chol, InsulinPlasma Glucose, TG, Chol, Insulin
Insulin Resistance Model
Fructose-Fed Syrian Golden Hamster
18. Evidence for Development of Insulin Resistance:Evidence for Development of Insulin Resistance:
• Increased Plasma Insulin, FFA, TriglycerideIncreased Plasma Insulin, FFA, Triglyceride
• Reduced whole body insulin sensitivity (based on Euglycemic-Reduced whole body insulin sensitivity (based on Euglycemic-
Hyperinsulinemic Clamp Studies)Hyperinsulinemic Clamp Studies)
Adeli K. et al. (2000) J. Biol. Chem. 275: 8416-8425.
Evidence for Development of Hepatic VLDL Overproduction:Evidence for Development of Hepatic VLDL Overproduction:
• Enhanced hepatic VLDL secretion In Vivo (Triton method)Enhanced hepatic VLDL secretion In Vivo (Triton method)
• Enhanced VLDL secretion by primary hamster hepatocytesEnhanced VLDL secretion by primary hamster hepatocytes ex vivoex vivo
• Increased intracellular apoB stabilityIncreased intracellular apoB stability
• Enhanced MTP expression (mRNA, protein, activity)Enhanced MTP expression (mRNA, protein, activity)
Insulin Resistance Model
Fructose-Fed Syrian Golden Hamster
Hypothesis I:Hypothesis I:
Insulin Resistance Induces Hepatic VLDL Overproduction
Published Data:
24. Insulin Signaling Status in Hepatocytes:Insulin Signaling Status in Hepatocytes:
• Ex vivoEx vivo Analysis of Insulin Receptor, IRS-1, PI3-kinase,Analysis of Insulin Receptor, IRS-1, PI3-kinase,
PTP-1B in Control and Fructose-Fed Hamster LiversPTP-1B in Control and Fructose-Fed Hamster Livers
• In VitroIn Vitro Analysis of Insulin Receptor, IRS-1, PI3-kinase,Analysis of Insulin Receptor, IRS-1, PI3-kinase,
PTP-1B in Primary Hepatocytes Exposed to High InsulinPTP-1B in Primary Hepatocytes Exposed to High Insulin
Link between Insulin Signaling & VLDL-apoB Secretion:Link between Insulin Signaling & VLDL-apoB Secretion:
• In VitroIn Vitro Analysis of ApoB Secretion in Primary HepatocytesAnalysis of ApoB Secretion in Primary Hepatocytes
Exposed to High InsulinExposed to High Insulin
• Inhibition of Protein Phosphatases byInhibition of Protein Phosphatases by VanadateVanadate and its Impact onand its Impact on
VLDL-apoB SecretionVLDL-apoB Secretion
(J. Biol. Chem. (2002) 277, 793-803)
Hypothesis II:Hypothesis II:
VLDL-apoB Overproduction is Linked to Hepatic Insulin ResistanceVLDL-apoB Overproduction is Linked to Hepatic Insulin Resistance
Insulin Resistance Model
(Fructose-Fed Hamster)
Recent Data:
25. Y
Insulin Signaling Pathway
Insulin
InsulinReceptorInsulinReceptor
αα
ββ
Y PP
IRSIRS
ProteinsProteinsSHC
Grb2
mSoS
Grb2
mSoS
RaS
p85p85
p110p110
PI 3-KinasePI 3-Kinase
PDK1 (PDK2)
AktAkt
PTP-1B
PTP-1B
PP PP
PTEN
aPKCs PDE BAD
Anti-
apoptosis
Anti-
lipolysis
Glucose
transport
Gsk3ToRp70rak
Glycogen
synthesis
Protein
synthesis
RAF
MEK
MAPK
Gene Expression/
mitogenesis
90rak
Plasma membrane
Protein kinase
CK2
Ser/Ther-p
CAP
CblcrkII
Caveolae
Glucose & Lipid
metabolism
Gab 1Shp-2
VanadateVanadate
30. Postulated Mechanisms of Insulin ResistancePostulated Mechanisms of Insulin Resistance
PTP-1BPTP-1B Mass & ActivityMass & Activity
Impaired Phosphorylation ofImpaired Phosphorylation of
Insulin Receptor, IRS-1Insulin Receptor, IRS-1
PI-3 Kinase ActivityPI-3 Kinase Activity
Attenuated Insulin SignalingAttenuated Insulin Signaling
Reduced Phosphorylation of ApoB orReduced Phosphorylation of ApoB or
an apoB-chaperonean apoB-chaperone
Enhanced Stability and Accelerated Assembly of ApoBEnhanced Stability and Accelerated Assembly of ApoB
Overproduction of VLDLOverproduction of VLDL
ER-60MTP
31. Intestine
Contribution of the Intestinal LipoproteinsContribution of the Intestinal Lipoproteins
to Metabolic Dyslipidemia in Insulin Resistanceto Metabolic Dyslipidemia in Insulin Resistance
Liver
ApoB48
ApoB100
Intestinal Lipoprotein Metabolism
33. Hypothesis III:
Fasting and postprandial hyperlipidemia in insulin resistant states
may be attributable in part to intestinal oversecretion of apoB-48
containing lipoproteins
Experimental Approach:
• Dietary induction of an insulin resistant state in the hamster by
high fructose feeding
• Isolation of adult viable villi from Syrian hamster small intestine.
• -In Vivo Studies to assess production rate of intestinal (apoB48-
containing) lipoproteins
• -Ex Vivo Studies to assess intestinal apoB48 lipoprotein synthesis
and secretion, mechanisms of chylomicron assembly, role of de
novo lipogenesis in intestinal lipoprotein secretion in the fasting
and postprandial states
34. Secretion and Regulation of ApoB48 by
Primary Hamster Intestinal EnterocytesIntestinal Enterocytes
B C
LabeledApoB48(%control)
LabeledApoB48(%control)
0
20
40
60
80
100
120
Total Cells Media
Control
MG132
P < 0.05
0
20
40
60
80
100
120
Total Cells Media
Control
Oleate
P = 0.01
Cells Media
0 45 90 45 90
A
Chase Time (min)
35. Cells Media
Fructose-Fed
Chow-Fed
Chase Time (Min)
0 45 90 45 90
D
Chase Time (Min) Chase Time (Min)
100
100
0
10
20
30
40
50
60
70
80
90
0 20 40 60 80
Total apoB 48
LabeledApoB48(%of0Time)
LabeledApoB48(%of0Time)
p= 0.003 p= 0.001
Secreted apoB 48
0
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100
Chow-Fed
Fructose-Fed
E F
Ex vivo evidence for oversecretion of intestinal apoB48
& Enhanced intracellular apoB48 stability in fructose-
fed hamster enterocytes
36. In Vivo Production of TG & Intestinal ApoB48
in the Fasting State
Time (min)
55 60 65 70 75 80 85
Sf>400TGconcentration
(mmol/l)
0
1
2
3
4
Sf >400 after Triton WR1339
Time (min)
55 60 65 70 75 80 85
Sf>400ApoB48concentration
(µg/ml)
140
160
180
200
220
240
260
280
Time (min)
55 60 65 70 75 80 85
Sf100-400TGconcentration
(mmol/l)
0
1
2
3
Sf 100-400 after Triton WR1339
Time (min)
55 60 65 70 75 80 85
Sf100-400ApoB48concentration
(µg/ml)
90
100
110
120
130
140
150
160
170
Triglyceridesecretion
0.0
0.2
0.4
0.6
0 1 2 3
ApoB48secretion
0
4
8
12
16
Triglyceridesecretion
0.0
0.1
0.2
0.3
ApoB48secretion
0
2
4
6p = 0.002 p = 0.01
p = 0.14
p = 0.59
A B
DC
37. In Vivo Production of TG & Intestinal ApoB48
in the Postprandial State
Time (min)
55 60 65 70 75 80 85
Triglyceridelevel(mmol/l)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Time (min)
55 60 65 70 75 80 85
ApoB48level(µg/ml)
80
90
100
110
120
130
140
150
Time (min)
55 60 65 70 75 80 85
Triglyceridelevel(mmol/l)
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Time (min)
55 60 65 70 75 80 85
ApoB48level(µg/ml)
50
60
70
80
90
100
Triglyceridesecretion(µmol/min)
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Col 48: 0.07
Col 48: 0.06
Triglyceridesecretion(µmol/min)
0.00
0.02
0.04
0.06
0.08
0.10
Col 50: 0.08
Col 50: 0.09
0 1 2 3
ApoB48secretion(µg/min)
0
1
2
3
4
5
6
7
8
Col 52: 2.65
Col 52: 7.46
ApoB48secretion(µg/min)
0
1
2
3
4
5
6
7
8
Col 54: 3.85
Col 54: 7.26
Sf 100-400 after Triton WR1339
Sf >400 after Triton WR1339
A B
C D
p = 0.3 p = 0.003
p = 0.8 p = 0.007
38. 0
20
40
60
80
100
120
140
160
Fructose-Fed
MTPProteinMass
(%ofControl)
Chow-Fed Fructose-Fed
0
20
40
60
80
100
120
0 0.5 1 1.5 2 2.5 3 3.5
MTP inhibitor (µM)
ApoB48Secretion(%ofcontrol)
Fructose-fed
Chow-fed
∗
∗ ∗ ∗
Chow-Fed
p=0.006D
E
LabeledCholesterylEster
(%ofControl)
p= 0.002
0
50
100
150
200
250
Cellular
p=0.001
Media
B
LabeledCholesterol
(%ofControl)
Chow-Fed
Fructose-Fed
0
100
200
300
400
500
600
700
800
Cellular
p=0.0018
p=0.0013A
Media
LabeledTriglyceride
(%ofControl)
Cellular
0
20
40
60
80
100
120
140
160
180
p=0.04
p=0.003
Media
C
Ex Vivo Evidence for Intestinal Overproduction of
Lipoprotein Lipids and Increase MTP mass/activity
39. Fructose-Fed
Chow-fed
0
10
20
30
40
50
60
70
80
Large
CM
Small
CM
VLDL LDL HDL
p<0.05
p= 0.06
p<0.03
%ofTotalLabeledApoB48 A
0
20
40
60
80
100
120
140
CM apoB48 Total-apoB48
LabeledApoB48
(%ofFructose-fed)
p<0.0007
p<0.01C
0
10
20
30
40
50
60
70
80
Particles< 1.006 Particles > 1.006
%ofTotalLabeledAPoB48
p<0.024
p<0.026
B
0
40
20
60
80
100
120
CM apoB48 Total apoB48
LabeledApoB48
(%ofFructose-fed)
P=0.008 P=0.0001
DFasting Postprandial
Density/Size Distribution of Intestinal Lipoproteins
Evidence for Increased Number & Size
40. Increased De Novo Lipogenesis in FF Enterocytes
Evidence that ApoB48 Secretion is Linked to
the Rate of De Novo Lipogenesis
0
10
20
30
40
50
60
70
80
90
100
110
0 2 4 6 8 10 12 14 16
Cholesterol
Fatty Acid
Triglyceride
LabeledLipid(%ascontrol)
Cerulenin µg/ml
0
50
100
150
200
250
300
350
Chow-fed Fructose-fed
LabeledFattyAcid(%ascontrol)
0
10
20
30
40
50
60
70
80
90
100
110
0 2 4 6 8 10 12 14 16
Cerulenin µg/ml
LabeledSecretedApoB-48(%ascontrol)
A
C
p= 0.002
Sensitivity of ApoB48 Secretion
to Cerulenin
Fatty Acid
Synthesis
Sensitivity of TG & FA Secretion
to Cerulenin
41. 20
60
80
100
0
40
120
Chow-fed Fructose-fed
(2 days)
0
20
40
60
80
100
120
Control Fructose
(3mM )
0
200
400
600
800
1000
enterocytes hepatocytes
P < 0.01
LabeledApoB-48(%ofcontrol)
LabeledApoB-48(%ofcontrol)
Labeledcholesterol
0
50
100
150
200
250
300
350
400
450
enterocytes hepatocytes
LabeledTriglyceride
P < 0.0001
Acute Fructose Feeding or Exposure Does NOT Affect
Intestinal ApoB48 Secretion
[14
C] Fructose
Incorporation
into TG &
Cholesterol
Two-day Fructose
Feeding In Vitro Incubation
of Enterocytes with
Fructose
42. Mechanisms of Intestinal Lipoprotein
Overproduction in Insulin Resistant/
Hyperinsulinemic States
Apical Surface
Basolateral Surface
FA
monoglyceride
FABP-FA
FABP
TG
TG
TG
ApoB48
PL
CE
De Novo (FA)
Insulin (??)
TGdietary
SOS
Grb-2
IRS
PI3-K
p110
SHP-2
NCK
PTKPTK
β β
α α
IR
PKB (Akt)
SREBP1c
FAS & ACC
Glucose
+
FA
MTP
ERER
GolgiGolgi
Intestinal
Enterocyte
TG
ApoB48 Lipoprotein
Particles
p85Proteasome
Degradation
43. Acknowledgements
Laboratory Group:
Changiz Taghibiglou
Mehran Haidari
Steven Van Iderstine
Wei Qui
Taryne Chong
Farhana Mahboob
Biao Chen
Leyla Mangaloglu
Louisa Pontrelli
Fariborz Rashid
Rita Kohen
Debbie Rudy
Collaborators:
Gary Lewis- Toronto
Andre Carpentier- Sherbrooke
Sven Olof Olofsson - Sweden
Janet Sparks - Rochester, NY
Raphael Cheung – Windsor
Michel Tremblay – Montreal
Denny Trinh - Toronto
Funding:
Heart & Stroke Foundation of Ontario
Canadian Institutes of Health Research
NSERC Hospital for Sick Children
Merck-Frosst pfizer
GlaxoSmithKline
BBDC, University of Toronto
44. DNA Microarray
Mehran Haidari PhD
Application in Vulnerable plaque research
Center for Vulnerable Plaque Research
University of Texas-Houston
& Texas Heart Institute
45. Atherosclerosis and the resulting coronary heart disease represent the most
common cause of death in industrialized nations.
Although certain key risk factors have been identified, the molecular mechanism
responsible for this complex disease and its deadly complications remains as a
challenge in the years to come.
Rupture of atherosclerotic plaque is the predominant underlying process in the
pathogenesis of acute coronary syndromes.
Although we have gained a great deal of knowledge on underlying pathology
involved in plaque vulnerability to rupture, the exact molecular mechanisms
underlying the process is still largely unexplored.
46. Evolution of genomic and proteomic techniques has opened the door to the
world of unknown molecular mechanisms in the body that allowing
thorough investigation into susceptibility of certain people / patients to
certain outcomes.
Investigation of advanced atherosclerosis using the tools for systematic gene and
protein expression analysis is a surprisingly neglected area of study and has not
been touched widely enough. Only a few numbers of investigators worldwide are
actively pursuing this field. (B.C.G Faber, J.A.P Deamen; L.D Adams, Stephen
M.Schwartz; M.P. Herman, Uwe Schonbeck; k.J.Haley, Richard T Lee; Timothy
A.McCaffrey;L.W.Stanton, R Tyler White;D.Shiffman, Richard M Lawn;Brian K
Coombes, )
Deamen Schwartz Lee
47. During the last half of the 20th
century, the analysis of the regulation and function
of genes largely Been driven by step-by-step studies of individual genes and proteins.
In the past decade, a paradigm shift has emerged in which
we are now able to produce large amounts of data about many
genes in a highly parallel and rapidly serialized manner.
An important tool in this process has been
the development of DNA microarray.
48. Low-throughput methods of gene expression
Northern Blotting, cumbersome, time-consuming
Nuclease protection, at least 10 fold more sensitive
Quantitative RT-PCR, state of the art
High-throughput Methods of gene expression
Serial Analysis of Gene Expression (SAGE)
Rapid Analysis of Gene Expression (RAGE)
Representational Difference Analysis (RDA)
Suppression Subtractive Hybridization (SSH)
Differential screening (plus/minus screening)
Differential Display (DD)
DNA Microarray =400,000 Northern Blotting
49. What is DNA Microarray?
A large number of genes deposited onto a glass slide (large scale dot blot).
The RNA sample is RT with simultaneous incorporation of label,
resulting in labeled cDNA.
Microarray slides serve as hybridization targets for labeled cDNA.
Reverse Northern blotting
Patrick O Brown
Mark Schena
50. Basic Steps in Performing a DNA Microarray Experiments
1- Processing cDNA clones to generate print-ready material
2-Printing cDNA clones (or oligonucleotide) onto a substrate
3-Sample RNA isolation
4-Preparation of the probe (e.g. cDNA synthesis and labeling, RT reaction)
5- Hybridization of labeled probe DNA to the DNA arrayed on the substrate
6-Image acquisition, image analysis and data analysis
51. Microarray Fabrication Technologies
In Situ Synthesis of Nucleic Acid (Chip ,GeneChip,oligonucleotide array)
15-20 different 25-mer oligonucleotides
Exogenous Deposition of cDNA (cDNA, spotted array)
Single DNA fragments, greater 0.5 Kb
52. Analysis of Gene Expression
Monitoring Changes in Genomic
DNA
Gene Discovery, Sequencing and Pathway Analysis
When to use Microarray
53. Analysis of Gene Expression
1- Different tissues or different developmental states.
2- Normal or diseased states.
3- Exposure to drugs or different physiological conditions.
54. Two basic substrates commonly used for cDNA printing
are glass and membrane filters.
Chemically treated microscope glass slides are the most
widely used support.
Microarray, Microscope Slide,80000 Spots.
Macroarray, Nylon Membrane, 500,-18000 Spots.
Micro or Macro
55. RNA Preparation
No difference between total RNA or mRNA
Type of tissue might have profound effect on extraction
process. 10 -20 µg of RNA is needed/slide.
Laser captured microdissection (LCM) , incorporation of a
PCR step( access to subpopulations cells in vulnerable plaque).
56. Sample Labeling
Most microarray utilize two fluorophores,
Cyanine3(Green emission) and Cyanine5 (Red emission).
Fluorophores have different size and different ability
for incorporation in Cdna.
A single round of transcription is used to generate
a labeled cDNA probe (RT-PCR).
57. Affymetrix Genechip
Biotinylated cRNA is synthesized from cDNA
phycoerthrin linked to avidin is used for labeling.
Each sample hybridized separately
Advantages
High density chip
Consistent and uniform geometry
Single Nucleotide Polymorphisms(SNP)
No need for maintaining cDNA clones
Disadvantages
Sequence data required
Oligonucleotid selection rules
are not well defined
Not best target for hybridization
Expensive
Hybridization to oligonucleotide is sensitive in
detection of single-nucleotide mismatches.
58. No consensus on Data Analysis( ANOVA), Clustering
(categorizing genes according to their pattern of expression).
Normalization
First step is during scanning, when sensitivity of
detection is adjusted by the laser voltage.
Gene expression value can be expressed relative
to the expression of housekeeping genes.
In the absence of control genes, normalization to the median
microarray value is popular.
59. Analyzed gene changes are often expressed as a fold increase
either greater than twofold or less than 0.5 fold (DeRisi).
How Much is Significant???
With a large number of microarrays, small changes can be statistically valid.
Elcock et al. detected 1.1 fold changes with 95 % confidence interval when
each experimental sample was hybridized to
seven microarray slides (with two replicate spots for each gene).
Derisi et al.Nat Genet 1996:14:457-60
60. Housekeeping genes
These are genes that are expressed constitutively and their level of
expression is thought to be stable, regardless of the sample used (β
Actin, Cyclophilin, GAPDH).
DeRisi used 90 housekeeping genes and found that changes that
were <0.5 and > 2.4 were acceptable.
β Actin is one of the most commonly used housekeeping genes
and it has been shown to be downregulated in heat shock experiments.
In fact, there is an appreciable amount of literature available to
suggest that there is no such thing as housekeeping gene.
61. DNA microarray represents a developing technology, there remain
substantial obstacles in the design and analysis of these microarray.
There are no globally accepted rules or standards
for performing controlled microarray experiments.
A good experiments include more control component then
the real comparison.
Accuracy and Precision
62. Principles of Q.C in DNA Microarray
Replication of each experiments on multiple array.
Dual labeling, swapping the dyes for control and treated sample.
Using a large number of controls on every array.
Rajeevan et al. estimated that 30% of
microarray results are false-positive.
Microarray findings should be confirmed, at least
by one of the low-throughput gene expression methods.
Down-Scaling of an experiment makes it generally
sensitive to external and internal fluctuation.
J.Mol.Diag 2001,3:26-31
63. Controls
mRNA from genes that are not homologous to the organism understudy (Arabidopsis).
cDNA from the organism with high, medium and
low expression represented on the array (sensitivity).
Cold DNA (e.g., calf thymus DNA, yeast tRNA)
is added to block nonspecific annealing.
Spots of DNA from another organism whose
mRNA is not represented in the sample (Background).
Total genomic DNA or cDNA clones of common contaminant such
as E.Coli and yeast are represented in the array to monitor for contamination.
64. The number of genes encoded by the Human genome has been
estimated ∼ 32,000 - 38,000.
Between 21,000 - 27,000 genes are expressed in the cardiovascular system
Lack of information
No cDNA Library for Atherosclerotic plaques
Only 5% of total ESTs deposited in GeneBank derived from cardiovascular tissue.
ESTs from cardiovascular tissues or cell type
or from diseased specimens remain limited.
65. Cardiovascular EST data from most model organisms are almost nonexistent.
The construction of cardiovascular gene databases at different
stages of pathology cast light on the complex genetic
mechanisms underlying disease of cardiovascular system.
DNA microarray technology is in infancy
DNA microarray in atherosclerosis was not
born or at least is premature.
Premature
66. The first study dealing with differential gene expression in whole-mount
specimens of rupture plaques using macroarray.
Suppression Subtractive Hybridization (SSH) technique isolates low abundant
sequence that might not be isolated by use of microarray technology.
Mammalian mRNA population
20% Abundant transcript (1000-12000 copies/cell)
25% Medium abundant (100-1000 copies/cell)
% 50 small number copies (< 13 copies/cell)
Mammalian mRNA encoding proteins that regular cellular
behavior are expressed at low abundance.
Identification of Gene Potentially Involved in Rupture of
Human Atherosclerosis Plaques.
Circ Res 2001;89;547554
Deamen
67. Perilipin was the known gene that up regulated (confirmed by RT-PCR) , 8 of 10
ruptured plaques expressed perilipin while expression was absent in 10 stable plaque.
Perilipin is a protein which present on the surface layer of
intracellular lipid droplets in adipocyte and prevent lipolysis.
They speculated that the increase in perilipin result in increased lipid
retention and plaque destabilization.
β actin was down regulated in ruptured plaques.
The down regulation of one gene was not confirmed by RT-PCR.
A pool of 3 ruptured plaques was compared with a
a pool of advanced but stable plaques.
68. Prelipin is unlikely to be the sole marker of rupture.
The author used only 10% of differentially expressed gene for doing macroarray
A large effort at macroarray and then sequencing would have yield more differences.
An alternative would be to hybridized the subtractand against a large array.
Other alternative is the isolation of cell type-specific genes
(LCM) rather than plaque-type-specific genes.
(Stephen M.Schwartz et al.Circ Res 2001:89;471-473)
69. Richard T Lee et al. Treated cultured Human aortic SMC with
TNFα and used DNA microarray with 8600 genes to monitor the gene expression.
Marked increase in eotaxin confirmed with northern blotting.
Immunohistochemical analysis demonstrated overexpression of
eotaxin and its receptor in the Human atheroma (SMC).
Circulation;2000:102:2185-2189
70. McCaffrey et al. compared transcript profile of fibrous cap vs adjacent media
of 13 patients ,using macroarray (membrane 588 known genes).
Early growth response gene(Egr-1) was highly
expressed in lesion (confirmed by RT-PCR).
Many Erg-1 inducible genes including PDGF , TGF-β and ICAM-1
were also strongly elevated in the lesion.
Immunocytochemistry indicated that Egr-1 was expressed in SMC.
β ACTIN and GAPDH were use as housekeeping gene.
J.C.I 2000,105:653-662
71. Adams et al. Compared gene expression of media of aorta and
vena cava, using cDNA microarray of 4048 known genes.
68 genes had consistent elevation in message expression the aorta.
The most differentially gene was Regulator of G Protein Signaling (RGS5).
Northern analysis and in situ hybridization were used to confirm the results.
Circulation Research 2000.8.623
72. R.M Lawn et al. examined the response of macrophages to exposure to
oxidized LDL, using microarray containing 10000 Human genes.
268 genes were found to be at least twofold up regulated.
Real Time -PCR was used to confirm the results.
Orphan nuclear receptors (PPARγ, LXR and RXR) and ABC1 were
among genes which unregulated after exposure.
J.B.C 2000:275;48, 37324-37332
73. L.A Mcintire et al. identified 52 genes with altered expression under shear stress
Using DNA microarray in primary human umbilical vein endothelial cells.
Significant increases in mRNA levels for 32 and significant
decreases in expression for 20 genes were reported.
The most enhanced genes were cytocromes P45 1A1 and 1B1
and human prostaglandin transporter.
Most dramatically down regulated genes were
connective tissue growth factor and endotheline-1.
Northern blot analysis confirmed the results obtained on microarray.
PNAS2001, 98:8955-8960
74. Brian K Coombes et al. used DNA macroarray to study the transcriptional
response of Endothelial cells to infection with C.Pneumonia.
C.Pneumonia infection up regulated m RNA expression for approximately
8% (20) of the genes studies (268).
Genes coding for cytokines (IL-1), Chemkines (MCP-1) and cellular growth factor
(PDGF) were the most prominently up regulated genes.
75. Proteomic is the study of the proteom or
the entire protein complement of a genom
It has been readily apparent that examining changes in the proteom
offers insight into Understanding cellular and molecular mechanisms
that cannot be obtained through genomic analysis.
A recent study analyzing human liver samples determined
the correlation coefficient between the amount of m RNA
present to the corresponding protein abundance to be
0.48 (Anderson and Seilhamer 1997).
76. Many genes are expressed constitutively and regulation
of their function is at the translational or posttranslational
Levels (ApoB ,CFTR, TCR).
Several studies have demonstrated selective TnI degradation under
Ischemia/reperfusion, partly responsible for contractile dysfunction
Observed after myocardial ischemia.( Circ Res.1999;84;9-20)
Virtually all known cellular signaling pathways are largely mediated
through a complex cascade of reversible protein phosphorylation.
77. Acute insults to cells lead to alteration in phenotype through rapid posttranslational
Modification of proteins, whereas in chronic disease states cotranslational and
Posttranslational protein modification occur in concert with altered gene expression.
Most proteomic studies in cardiovascular focused
in dilated cardiomyopathy and there is no report
of proteomic evaluation in vulnerable plaque.
Global proteome analysis provides a better representation of the
phenotype than does gene expression analysis.
78. Our research group at the vascular biology laboratory of Center for Vulnerable
Plaque Research in Texas Heart Institute is conducting a series of genomic and
proteomic experiments to shed light on the possible molecular mechanisms
involved in the onset and pathogenesis of atherosclerosis.
Differential gene and protein expression of morphologically advance, but stable
human atherosclerotic lesions and ruptured human atherosclerotic lesions are
examined in a large number of patients in the whole-mount specimens.
79. Transcript profile of blood monocytes from coronary patients with different
presentations and healthy controls will be examined to address the association of
gene expression and SNP with coronary risk.
Furthermore, Laser Captured Microdissection technology will be employed to
evaluate gene and protein expression in different cell populations of atheroma
plaques correlated with other markers (such as pH, Temperature, …).
We hope these approaches lead to better understanding of the
molecular process involved in development and complication of
vulnerable plaques.
80. The lack of information in genomic and particularly
proteomic approaches in vulnerable plaque is
apparent and this highlights need for genomic and
proteomic evaluation of plaque destabilization
81.
82. Coronary Atherosclerosis with Multislice CT:
What is beyond coronary atherosclerosis
Konstantin Nikolaou
Tobias Jakobs
Bernd Wintersperger
Radiology
Alexander Becker
Andreas Knez
Alexander Leber
Cardiology
Michael Muders
Pathology
Christoph R Becker
109. Plaque Distribution
Leber 2001 Circulation
Non-
calcifie d
13%
Mixe d
33%
Calcifie d
54%
Myocardial Infarction
n = 12
122 Plaque
Stable Angina
n = 12
135 Plaque
Non-
calcifie d
6%
Mixe d
14%
Calcifie d
80%
110. Summary
• Detection of stenoses
– Calcium
– Small vessels
• Characterization of
plaques
• Identify atheromas
• Follow up under therapy
• Acute coronary event
• Intracoronary thrombus
• Myocardial infarction
112. Coronary Endothelial Shear Stress Profiling
In-Vivo to Predict Progression of
Atherosclerosis and In-Stent Restenosis in Man
Peter H. Stone, M.D.
Ahmet U. Coskun, Ph.D.
Scott Kinlay, M.D., Ph.D.,
Maureen E. Clark, M.S.
Milan Sonka, Ph.D.
Andreas Wahle, Ph.D.,
Olusegun J. Ilegbusi, Ph.D.
Yerem Yeghiazarians, M.D.
Jeffrey J. Popma, M.D.
Richard E. Kuntz, M.D., M.S.
Charles L. Feldman, Sc.D.
Cardiovascular Division, Brigham & Women’s Hospital, Harvard Medical School;
Department of Mechanical, Industrial and Manufacturing Engineering,
Northeastern University;
Department of Electrical and Computer Engineering, University of Iowa
113. Abstract - 1
The focal and eccentric nature of CAD must be
related to local hemodynamic factors. The endothelium is
uniquely capable of controlling local arterial responses by
transduction of hemodynamic shear stress. Low or
reversed shear stress (< ~10 dynes/cm2
) leads to plaque
development and progression. Physiologic shear stress
(~10 - 30 dynes/cm2
) is vasculoprotective, maintaining
normal vascular morphology. Increased shear stress
(> ~ 30 dynes/cm2
) promotes outward remodeling and
platelet aggregation.
Characterization of shear stress along the coronary
artery may allow for prediction of progression of
atherosclerosis and vascular remodeling.
114. Abstract - 2
Current methodologies cannot provide adequate
information concerning the micro-environment of the
coronary arteries. We developed a unique system using
intravascular ultrasound (IVUS), biplane coronary
angiography, and measurements of coronary blood flow, to
present the artery in accurate 3-D space, and to produce
detailed characteristics of intravascular flow, ESS, and
arterial wall and plaque morphology.
We observed that over 6 mo followup, areas of low
ESS demonstrated plaque progression, areas of
physiologic ESS remained quiescent, and areas of
increased ESS developed outward remodeling.
The technology may be invaluable to study the
impact of pharmacologic or device interventions on the
natural history of coronary disease.
115. Fundamental Nature of the Problem
• Although all portions of the coronary arterial tree
are exposed to the same systemic risk factors,
atherosclerosis is focal and eccentric
• Each coronary artery has many different
obstructions in different “stages” of evolution:
– There is not a “wave-front” of vulnerability
and consequent rupture.
117. Fundamental Nature of the Problem
• Coronary atherosclerotic obstructions behave differently
based on the degree of luminal obstruction and morphology:
– Lesions > 50-75% obstruction Angina Pectoris
– Lesions < 50% obstruction Rupture,superimposed
thrombus,
MI, death
These small, potentially lethal lesions are,These small, potentially lethal lesions are,
therefore, “clinically silent” until they rupture.therefore, “clinically silent” until they rupture.
• It would be of enormous value to identify minorIt would be of enormous value to identify minor
obstructions which were progressing and/orobstructions which were progressing and/or
evolving towards “vulnerability” since they could beevolving towards “vulnerability” since they could be
treated before rupture occurred, thereby avertingtreated before rupture occurred, thereby averting
an acute coronary syndrome.an acute coronary syndrome.
118. Nature of Progression of Atherosclerosis
• The only truly local phenomena which could lead to varying
local vascular responses are endothelial shear stresses (ESS)
• Local ESS variations are critical:
– Low ESS and disturbed flow (< 6-10 dynes/cm2
)
• Causes atheroma; pro-thrombotic, pro-migration, pro-apoptosis
– Physiologic shear stress and laminar flow (10-30
dynes/cm2
)
• Vasculoprotective, anti-thrombotic, anti-migration, pro-survival
– High shear stress and turbulent flow (> 30 dynes/cm2
)
• Promotes platelet activation, thrombus formation, and probably
plaque rupture
• Until now,Until now, in vivoin vivo determination of intracoronary flow velocitydetermination of intracoronary flow velocity
and endothelial shear stress has not been possible.and endothelial shear stress has not been possible.
119. The Detrimental Effect of Low Shear Stress on
Endothelial Structure and Function
Low shear stresses and disturbed
local flow (< ~ 6 dynes/cm2
)
are atherogenic:
(Malek, et al. JAMA 1999; 282:2035)
• Cell proliferation, migration
• Expression of vascular adhesion
molecules, cytokines, mitogens
• Monocyte recruitment and activation
• Procoagulant and prothrombotic state
• Local oxidation
Promotes:
120. The Effect of Physiologic Shear Stress on
Endothelial Structure and Function
Physiologic shear stress
(~15-50 dynes/cm2
) is
vasculoprotective:
(Malek, et al. JAMA 1999; 282:2035)
• Enhances endothelial quiescence
- decreases proliferation
• Enhances vasodilation
• Enhances anti-oxidant status
• Enhances anti-coagulant and
anti-thrombotic status
121. Overview of Intracoronary Flow Profiling System
Patient • Coronary angiography
• Intracoronary ultrasound
• Coronary flow (TIMI Frame Count)
Acquire image data
3D reconstruction
of lumen, EEL, Plaque
Generation of grid
for Computational
Fluid Dynamics
Numerical
computation
Determination of
local velocity vectors
and shear stress
Application of
vascular data to
patient care
Prediction of
restenosis
Prediction of
CAD progression
122. Intracoronary Flow Profiling Methods
• The intracoronary ultrasound (ICUS) “core” is positioned in the
relevant section of the artery and a biplane angiogram is recorded
using dilute contrast.
• ICUS is performed with controlled pull-back at 0.5 mm/sec with
biplane angiography. ECG is simultaneously recorded for “gating.”
• A dynamic programming technique extracts the lumen and EEL
outline from the ICUS at end-diastolic frames and re-aligns them.
• The ICUS frames are realigned in 3-D space perpendicular to the
ICUS core image.
• The reconstructed lumen is divided into computational control
volumes comprising 0.3 mm thick slices along the segment, 40 equal
intervals around the circumference, and 16 intervals in the radial
direction.
• Dividing the blood into small “cubes” on the grid, the Navier-Stokes
equations of fluid flow are solved numerically using an iterative
procedure (Computational Fluid Dynamics).
• Shear stress at the wall is obtained by multiplying viscosity by the
velocity gradient at the wall.
129. Example of 3-D Reconstruction of
Coronary Artery
Solid line passing through the centroid of the lumen defines a pathline
Perpendicular distance between pathline and lumen border defines local lumen radius,
perpendicular distance between EEL border and pathline defines the local EEL radius
Difference between local EEL and lumen radii defines local plaque thickness
130. Original angiogram of
a portion of an artery
studied
Composite reconstruction of portion of the arterial segment,
consisting of outer arterial wall, plaque, and lumen:
Isolated view of reconstructed outer arterial wall:
Isolated view of reconstructed lumen:
Isolated view of reconstructed atherosclerotic plaque:
Example of 3-D Reconstruction of Arterial Segment
132. Coronary Endothelial Shear Stress
w
y
u
WSS
∂
∂
µ=
dynes/cm2
[Artery is displayed as if it were cut and opened longitudinally, as a
pathologist would view it.]
133. Reproducibility Studies of
Intra-coronary Flow Profiling Measurements
Cardiac catheterization and coronary angiography
– Patients studied completely with ICUS pullback
and biplane angiography (“Test A”)
– All catheters removed, and after a few minutes,
entire procedure repeated (“Test B”):
• catheters reinserted
• angle, skew, table height reproduced to mimic
the initial procedure
– All calculations performed to measure lumen,
outer vessel, plaque morphology, and endothelial
shear stress
134. Reproducibility of 3-D Coronary Artery
Reconstruction
“Test A” and “Test B” Performed Separately
Lumen Radius
[mm]
EEL Radius
[mm]
Plaque Thickness
[mm]
Endothelial SS
[dynes/cm2
]
r = 0.96 r = 0.95 r = 0.91 r = 0.88
Grid divided into 2,560-10,640 areas/artery (average 5,900/artery)
Each p < 0.0001
(Coskun, et al. JACC 2002, 39; 44A)
ArterialSegmentLength(mm)
135. In-Vivo Determination of the Natural History
of Restenosis and Atherosclerosis
• First pilot study of its kind in the world
• Complete intra-coronary flow profiling at index
catheterization and repeated at 6-month followup
• 10 patients enrolled:
– Followup catheterization completed in 8 patients
• one refused recath; one had clinical event prior to
recath
136. Pilot Study of Natural History of Progression of
Coronary Atherosclerosis and In-Stent Restenosis
Effect of Candesartan vs. Felodipine
ConsentandRandomize
Identification of
appropriate CAD
substrate:
-PTCA/stent
-obstruction < 50%
in adj artery, not
revascularized
Cath
# 1
Cath
# 2
Enter
BWH
System
Candesartan active
Felodipine placebo
Candesartan placebo
Felodipine active
Titration to BP < 140/90 mmHg
(Outpatient visits)
Time Line: Hours Time 0 Mo 1 Mo 2 Mo 3 Mo 6
Preliminary
identification
of hypertensive
patient
Inclusion Criteria:
• Hypertension
• CAD requiring stent
• Additional minor CAD
137. Pilot Study of Natural History of Progression of
Coronary Atherosclerosis and In-Stent Restenosis
Followup Status:
One patient refused repeat catheterization
One patient developed acute coronary syndrome
and required urgent cath and restenting
Serial Study Cohort: 8 patients
Native CAD Endpoints: 6 patients with serial studies
5 Felodipine and 1 patient Candesartan
Restenosis Endpoints: 6 patients with serial studies
3 Candesartan and 3 Felodipine
138. Pilot Study of Candesartan to Reduce Coronary
In-Stent Restenosis and
Progression of Atherosclerosis
Patient Population: 10 patients
9 men; 1 woman
Mean age: 60.8 years (range 37-83 years)
Concomitant medications: B-blockers, statins, and aspirin (all patients)
Mean fasting lipids: Total cholesterol: 156 mg/dl
LDL cholesterol: 95 mg/dl
HDL: 36 mg/dl
Triglycerides: 150 mg/dl
Blood Pressure:Baseline: 156/89 mmHg
Followup: 137/78 mmHg
139. Example of Coronary Atherosclerosis
Progression Over 6-Month Period
(Stone, et al. JACC 2002, 39: 217A)
Plaque Thickness [mm] Lumen Radius [mm] EEL Radius [mm] ESS [dynes/cm
2
]
Arterylength[mm]
Plaque Thickness
Increases in Areas
of Low ESS
Lumen Radius
Decreases in
Areas of Increased
Plaque Thickness
EEL Radius
Increases in
Distal Areas
ESS Increases
in Areas of
Plaque Increase
and Decreases
in Distal Areas
140. Example of Coronary Artery
“Outward Remodeling” Over 6-Month Period
Lumen Radius
[mm]
EEL Radius
[mm]
Plaque Thickness
[mm]
Endothelial SS
[dynes/cm2
]
Lumen radius
enlarges
Outer vessel radius
enlarges
Plaque thickness
does not change
ESS returns
to normal values
(Stone, et al. JACC 2002, 39: 217A)
ArterySegmentLength(mm)
141. Example of Instent Restenosis
Over 6-Month Period
Lumen Radius
[mm]
EEL Radius
[mm]
Plaque Thickness
[mm]
Endothelial SS
[dynes/cm2
]
Lumen radius
smaller within
stent,
larger outside
of stent
Outer vessel
radius
enlarges
Plaque thickens
within stent,
no change outside
stent
Endothelial
shear stress increases
within stent,
normalizes outside
stent
(Kinlay, et al. JACC 2002, 39: 5A)
ArterySegmentLength(mm)
142. Example of No Change in Stented Segment
Over 6-Month Period
Lumen Radius [mm] EEL Radius [mm] Plaque Thickness [mm] ESS [dynes/cm
2
]
ArterySegmentLength(mm)
(Kinlay, et al. JACC 2002, 39: 5A)
143. Conclusions
• This methodology allows for the first time in man the
systematic and serial in vivo investigation of the natural
history of CAD and consequent vascular responses.
• There are different and rapidly changing behaviors of
different areas within a coronary artery in response to
different ESS environments.
• The methodology can evaluate in detail the ESS that are
responsible for the development and progression of CAD,
as well as the remodeling that occurs in response to CAD.
• The technology may be invaluable to study the impact of
pharmacologic or device interventions on these natural
histories
144. References
• Asakura T, Karino T. Flow patterns and spatial distribution of atherosclerotic
lesions in human coronary arteries. Circ 1990; 66: 1045-66.
• Nosovitsky VA, et al. Effects of curvature and stenosis-like narrowing on wall
shear stress in a coronary artery model with phasic flow. Computer and
Biomed Res 1997; 9: 575-580.
• Malek A, et al. Hemodynamic shear stress and its role in atherosclerosis.
JAMA 1999; 282: 2035-42.
• Ward M, et al. Arterial remodeling. Mechanisms and clinical implications. Circ
2000; 102: 1186-91.
• Ilegbusi O, et al. Determination of blood flow and endothelial shear stress in
human coronary artery in vivo. J Invas Cardiol 1999; 11: 667-74.
• Feldman CL, et al. Determination of in vivo velocity and endothelial shear
stress patterns with phasic flow in human coronary arteries: A methodology to
predict progression of coronary atherosclerosis. Am Heart J 2002; 143: (in
press).
• Feldman CL, Stone PH. Intravascular hemodynamic factors responsible for
progression of coronary atherosclerosis and development of vulnerable
plaque. Curr Opin in Cardiol 2000; 15: 430-40.
145. References
• Coskun AU, et al. Reproducibility of 3-D lumen, plaque and outer vessel
reconstructions and of endothelial shear stress measurements in vivo
to determine progression of atherosclerosis. JACC 2002; 39: 44A.
• Stone PH, et al. Prediction of sites of progression of native coronary
disease in vivo based on identification of sites of low endothelial shear
stress. JACC 2002; 39: 217A.
• Kinlay S, et al. Endothelial shear stress identified in vivo within the stent
is related to in-stent restenosis and remodeling of stented coronary
arteries. JACC 2002; 39: 5A.
• Feldman CL, et al. In-vivo prediction of outward remodeling in native
portions of stented coronary arteries associated with sites of high
endothelial shear stress at the time of deployment. JACC 2002; 39:
247A.
146.
147. Multi-slice fast CT and Electron
Beam Tomography: the first
screening step in imaging
coronary atherosclerosis?
Stephan Achenbach, MD
Department of Cardiology,
University of Erlangen, Germany
148. Coronary artery disease events such as myocardial infarction or coronary death frequently
occur in previously healthy individuals without prior symptoms. Tests which permit
identification of individuals at increased risk may thereore be beneficial.
Since coronary events are in most cases caused by plaque rupture, imaging
methods which permit the identification and quantification of coronary atherosclerotic
plaque are potentially useful for risk stratification. Most non-invasive imaging techniques,
however, lack the combination of high temporal and spatial resolution which is necessary
to reliably visualize the coronary arteries.
Electron beam tomography (EBT) and, more recently, multi-slice spiral CT
have been shown to permit visualization and quantification of coronary calcium in a non-
invasive fashion. Coronary calcium is always caused by coronary atherosclerosis and the
amount of coronary calcification correlates to the overall atherosclerotic plaque burden.
Numerous clinical studies conducted by electron beam tomography have proven the
method´s potential to identify individuals at increased risk for coronary events through
detection and quantification of coronary calcifications. Most (but not all) studies have
demonstrated a higher predictive value of coronary calcifications as compared to
traditional risk factors. Even though some smaller studies have shown that mulit-slice CT
(MSCT) in conjunction with ECG-gated reconstruction techniques permits the detection
and quantification of coronary calcium with accuracies similar to electron beam
tomography, no clinical outcome data have so far been published using MSCT.
In conclusion, the detection and quantification of coronary calcification my be
a useful tool for the identification of individuals at increased risk for coronary events.
Abstract:
149. Coronary events - such as
myocardial infarction - are
usually caused by plaque
rupture and frequently occur
in previously asymptomatic
individuals
Introduction
150. Traditional risk factors
frequently do not permit
satisfactory identification of
individuals who are at
increased risk for coronary
artery events
Introduction
151. Imaging techniques for the non-
invasive detection of atherosclerotic
plaque in the coronary arteries may be
helpful to identify individuals at
increased coronary event risk.
However, both high temporal and high
spatial resolution are necessary to
visualize the corornary arteries in a
non-invasive fashion.
Introduction
152. Electron beam
tomography is a
cross-sectional x-
ray imaging
technique with a
temporal
resolution of 100
ms.
Introduction
154. Aquisition
protocols and
methods for
quantification of
coronary calcium
by EBT are
standardized and
large reference
data bases are
available1, 2
.
Severe calcification in LAD
Abscence of coronary
Introduction
155. Recent pre-clinical
work has shown that
multi-slice spiral CT
using the last
hardware generation
and sophisticated
ECG-correlated
image reconstruction
software also permits
coronary calcium
detection4,5
.
LAD calcifications in
retrospectively ECG-gated
multislice CT
Introduction
156. Introduction
However, care has to be taken in order to avoid motion artifacts
which may be more frequent due to the longer acquisition window
as compared to EBT
Same patient: prospectively triggered (left) and retrosplectively triggered MSCT
157. What is the rationale
behind the detection of
coronary artery
calcification?
Discussion
158. Why detect coronary calcium?
Coronary calcification is
always caused by
artherosclerosis 6
Discussion
159. Why detect coronary calcium?
The amount of
calcium correlates
to overall plaque
burden 7,8
However: no close relationship between calcium in a
vessel segment and degree of luminal stenosis.
Discussion
160. Even though calcium
does not permit to
specifically detect
vulnerable plaque, it
is wrong to assume
that calcified plaques
are stable or more
frequently stable
than non-calcified
plaques9
.
erosion
stable
vulnerable
healed
rupture acute
rupture
Presence of Calcium
Discussion
161. Discussion
Coronary calcium does not permit to
detect the „vulnerable plaque“, but it
permits to detect the patient with high
coronary atherosclerotic plaque burden
in an asymptomatic stage.
162. A number of clinical trials have
evaluated the predictive value of
coronary calcium detection by
electron beam tomography in
symptomatic and asymptomatic
individuals.
Discussion
163. Raggi et al10
:
632 asymptomatic patients
32 +/- 7 months follow-up
myocardial infarction and death
Annual event rate:
0.1% for calcium score of 0
2.1% for calcium score 1-99
4.1% for calcium score 100-400
4.8% for calcium score > 400
Raggi et al, Circulation 2000
Discussion
164. Arad et al11
:
1173 asymptomatic patients
1 year and 3.5 year follow-up
Risk ratio for coronary events: 23 for calcium
score > 160
Discussion
165. Meta analysis by O´Malley et al12
:
Calcium score above
median:
All events: RR 8.6
„Hard“ events: RR 4.2
Discussion
166. Discussion
In most studies, coronary calcium by EBT
was more predictive than conventional risk
Arad et al 1996: ROC 0.91 for calcium, 0.74 for RF
1173 asymptomatic subjects (mean age: 53 years)
Raggi et al 2000: OR 22 for calcium, 7.0 for RF
632 asymptomatic subjects (mean age: 52 years)
Detrano et al 1999: ROC 0.65 for calcium, 0.67 for RF
1196 asymptomatic high-risk subjctes (mean age: 67 years)
167. Keelan et al13
:
288 patients with CAD who underwent coronary
angiography. Follow-up 6.9 years.
Event-free survival was significantly higher for patients
with calcium score < 100 than for those with scores > 100.
Discussion
168. In summary, a number of studies have proven the
prognostic value of coronary calcium detection by
electron beam tomography in asymptomatic and
symptomatic populations.
Study results are not completely unanimous
concerning the superiority of coronary calcium
over traditional risk factors, but most studies
found coronary calcium to have a higher
predictive value.
No clinical outcome studies have so far been
performed using multi-slice CT.
Discussion
169. What is the potential clinical role of coronary
calcium detection?
AHA/ACC statement14
:
„A positive EBCT confirms the presence of coronary atherosclerotic
plaque.“
„Total amount of calcium correlates ... total amount of
atherosclerotic plaque.“
„A negative EBCT test makes the presence of atherosclerotic plaque,
including unstable plaque, very unlikely.“
„A high calcium score may be consistent with a moderate to high
cardiovascular event risk within 2-5 years.“
„A negative test ... low risk of a cardiovascular event in the next 2 to
5 years.“
Discussion
170. What is the potential clinical role of coronary
calcium detection?
In clinical practice, cleary low-risk and clearly
high-risk individuals probably do not need further
testing for risk stratification.
Intermediate risk patients, however, might profit:
ACC/AHA14
: „selected use of coronary
calcium scores when a physician is faced
with the patient with intermediate
coronary artery disease risk may be
appropriate“
Discussion
171. What is the potential clinical role of coronary
calcium detection?
Discussion
172. Role of EBT and MSCT in risk stratification?
Coronary calcium, even though it does not permit
to detect the „vulnerable plaque“, permits to
identify the patient with high plaque burden.
The detection of coronary calcium
therefore permits identification of
patients at increased risk for
coronary artery events.
It may be beneficially applied in
patients who seem to be at
„intermediate“ risk.
Conclusion
173. Initial results have shown that EBT and especially
MSCT - after i.v. injection of contrast agent - also
permit visualization of non-calcified plaque:
Partly calcified plaque in the
proximal right coronary
artery visualized by multi-
slice CT MSCT
Conclusion
176. Some authors have compared plaque
morphology in MSCT to intravascular
ultrasound15
, but the clinical
implications and the exact meaning of
non-calcified plaque in MSCT or
EBBT currently are not clear.
Conclusion
177. SUMMARY:
EBT and MSCT have sufficient spatial and
temporal resolution for coronary artery
visualization.
Clinical studies have shown a high prognostic
value of coronary calcium for identification of
asymptomatic individuals at increased coronary
artery disease risk.
The meaning of non-calcified plques which can
also be detected (after injection of contrast agent)
is not yet clear.
Conclusion
178. SUMMARY:
Future clinical studies, some are currenty being
conducted, will help to define the role of coronary
calcium detection in the clinical work-up of
patients ín whom risk stratification for coronary
artery events may be beneficial.
Conclusion
179. References
1. Hoff JA, et al: Age and gender distributions of coronary artery calcium detected by
electron beam tomography in 35246 adults. Am J Cardiol 2001;87:1335-1339
2. Raggi P: Introduction. Am J Cardiol 2001:88(2A);1E-3E.
4. Carr JJ, et al: Coronary artery calcium quantification with retrospectively gated
helical CT: protocols and techniques. Int J Card Imaging 2001;17:213-220
5. Becker CR, et al: Coronary artery calcium measurement: agreement of multirow
detector and electron beam CT. Am J Roentgenol 2001;176:1295-1298
6. Blankenhorn DH: Coronary arterial calcification. Am J Med Sci 1961; 41-50
7. Rumberger JA, et al: Coronary artery calcium area by electron-beam computed
tomography and coronary atherosclerotic plaque area. A histopathologic correlative
study. Circulation 1995:92:2157-2162.
180. References
8. Sangiorgi G, et al: Arterial calcification and not lumen stenosis is highly correlated
with atherosclerotic plaque burden in humans: a histologic study of 723 coronary artery
segments using nondecalcifying methodology. J AM Coll Cardiol 1998;31:126-133
9.Burke et al: Coronary calcification: insights from sudden coronary death victims. Z
Kardiol 2000;89(Suppl. 2):49-53
10. Raggi P et al: Identification of patients at increased risk of first unheralded acute
myocardial infarction by electron-beam computed tomography. Circulation
2000;101:850-855
11. Arad Y et al: Prediction of coronary events with electron beam computed
tomography. J Am Coll Cardiol 200:36:1253-1260
12. O´Malley et al: Prognostic value of coronary electron-beam computed tomography
for coronary heart disease events in asymptomatic populations. Am J Cardiol
2000;85:945-948
13. Keelan PC et al: Long-term prognostíc value of coronary calcification detected by
electron beam computed tomography in patients undergoing coronary angiography.
Circulation 2001;104:412-417
14. ACC/AHA expert consensus document on electron-beam computed tomography
for the diagnosis and prognosis of coronary artery disease. Circulation 2000;102:126-
140
15. Kopp AF et al: Non-invasive characterization of coronary lesion morphology and
composition by multislice CT: first results in comparison with intracoronary ultrasound. Eur Radiol
2001:1607-1611
181. Vascular InterventionsVascular Interventions
Ergin Atalar, Ph.D.Ergin Atalar, Ph.D.
Johns Hopkins UniversityJohns Hopkins University
Departments of Radiology and Biomedical EngineeringDepartments of Radiology and Biomedical Engineering
DISCLOSURE:DISCLOSURE:
E. Atalar is a founder and stock holder of Surgi-Vision, Inc.E. Atalar is a founder and stock holder of Surgi-Vision, Inc.
182. Johns Hopkins University
OverviewOverview
– Intravascular MRI (first human experiments)Intravascular MRI (first human experiments)
– Balloon AngioplastyBalloon Angioplasty
– Stent PlacementStent Placement
– MR-guided Gene TherapyMR-guided Gene Therapy
185. Johns Hopkins University
mm
B
FSE, 1200/13-msec TR/TE, Double IR blood suppression, 16 ETL, 4-cm FOV, 32 NEX,
256x256 matrix, 10 min 14 sec acquisition time
ACM
• Resolution: 150 µm
J. M. Serfaty et al.
Watanabe rabbit with a 0.032” MRI-GuidewireWatanabe rabbit with a 0.032” MRI-Guidewire
Aortic wall imagingAortic wall imaging
186. Johns Hopkins University
Post stent: human iliac IVMRIPost stent: human iliac IVMRI
L. Hofmann, D. Bluemke
Rt common iliac art.
Guidewire
(venous)
Fibrous cap
Lipid core
T1 - pre gad T1 - post gad
187. Johns Hopkins University
L. Hofmann, D. Bluemke
Fibrous cap
Lipid
core
Plaque CharacterizationPlaque Characterization
188. Johns Hopkins University
Restenosis - s/p renal stentRestenosis - s/p renal stent
5 mm
L. Hofmann, D. Bluemke
Rt renal artery
Guidewire
in IVC
restenosis
189. In-Vivo Human Iliac Artery:In-Vivo Human Iliac Artery:
Concentric AtherosclerosisConcentric Atherosclerosis
Angiography 20 MHz IVUS IVMRI
No Abnormality Concentric Atherosclerosis
5 mm 5 mm
Vein
K. Yucel, et. al. Brigham and Women’s Hospital
196. Dilatation with Gd filled balloonDilatation with Gd filled balloon
C. Rickers, 2001
197. Dilatation with air filled balloonDilatation with air filled balloon
C. Rickers, 2001
198. Johns Hopkins University
MR-guided Stent PlacementMR-guided Stent Placement
Technical ChallengesTechnical Challenges
– MR compatible and visible stent deploymentMR compatible and visible stent deployment
devicedevice
– MR compatible stentMR compatible stent
– Methods of monitoring stent placementMethods of monitoring stent placement
procedureprocedure
199. Johns Hopkins University
MR Guidewire Tracking/PlacementMR Guidewire Tracking/Placement
sheath
FGREFGRE
256x162256x162
20 mm slice20 mm slice
4 element4 element
cardiac coilcardiac coil
A. Lardo et. al.
200. Johns Hopkins University
MRI Guided Stent Positioning and DeploymentMRI Guided Stent Positioning and Deployment
stent
liver
stomach
Ao
SPGRSPGR
256x162256x162
TR/TE=4.4/1.2TR/TE=4.4/1.2
20 mm slice20 mm slice
4 element cardiac4 element cardiac
coilcoil
A. Lardo et. al.
201. Johns Hopkins University
Intravascular Wire Stent CrossingIntravascular Wire Stent Crossing
SPGRSPGR
256x162256x162
TR/TETR/TE
20 mm slice20 mm slice
3 element3 element
cardiac coilcardiac coil
+ 1 element+ 1 element
internal coilinternal coil
stent 1
stent 2
MRI
guidewire
A. Lardo et. al.
202. Johns Hopkins University
High Resolution Aortic ImagingHigh Resolution Aortic Imaging
stent
MRIG
(Imaging
Guidewire)
SPGR, 256x256, FOV=4 cm
Guidewire element only
stented
wall
156µm
A. Lardo et. al.
207. Johns Hopkins University
ConclusionConclusion
MRI has potential to guide new andMRI has potential to guide new and
conventional vascular interventionsconventional vascular interventions
208. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
““Macrophage-induced proteolysis:Macrophage-induced proteolysis:
how many MMPs and non-MMPs arehow many MMPs and non-MMPs are
involved?”involved?”??
Zorina S. Galis,Zorina S. Galis,
Ph.D.Ph.D.Division of Cardiology , EmoryDivision of Cardiology , Emory
University School of MedicineUniversity School of Medicine
Department of BiomedicalDepartment of Biomedical
Engineering Emory/Georgia Tech,Engineering Emory/Georgia Tech,
Atlanta GAAtlanta GA
March 16, 2002March 16, 2002
33rdrd
Vulnerable Plaque SymposiumVulnerable Plaque Symposium
March 16, 2002March 16, 2002
33rdrd
Vulnerable Plaque SymposiumVulnerable Plaque Symposium
209. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
LipiLipi
dd
corcor
ee
ThrombusThrombus
Natural history of humanNatural history of human
atherosclerosisatherosclerosis
Natural history of humanNatural history of human
atherosclerosisatherosclerosis
M. Davies,M. Davies,
19981998
Acute cardiovascular events representAcute cardiovascular events represent
a late stage of arterial remodelinga late stage of arterial remodeling
Acute cardiovascular events representAcute cardiovascular events represent
a late stage of arterial remodelinga late stage of arterial remodeling
adaptatioadaptatio
nn
sustainedsustained
adaptatioadaptatio
n andn and
repairrepair
destructiondestruction
Culprit = ruptureCulprit = ruptureCulprit = ruptureCulprit = rupture
210. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
SelectedSelected
MMPMMP
Selected substratesSelected substrates
StromelysinStromelysin
(SL / MMP-3)(SL / MMP-3)
StromelysinStromelysin
(SL / MMP-3)(SL / MMP-3)
Proteoglycans, fibronectin, lamininProteoglycans, fibronectin, laminin
pro-MMP-1, pro-MMP-9pro-MMP-1, pro-MMP-9
Proteoglycans, fibronectin, lamininProteoglycans, fibronectin, laminin
pro-MMP-1, pro-MMP-9pro-MMP-1, pro-MMP-9
Gelatinases (GL)Gelatinases (GL)
72 kD GL, GL a (MMP-2)72 kD GL, GL a (MMP-2)
92 kD GL, GL b (MMP-9)92 kD GL, GL b (MMP-9)
Gelatinases (GL)Gelatinases (GL)
72 kD GL, GL a (MMP-2)72 kD GL, GL a (MMP-2)
92 kD GL, GL b (MMP-9)92 kD GL, GL b (MMP-9)
Collagen type IV / VCollagen type IV / V
degraded collagen, elastindegraded collagen, elastin
Collagen type IV / VCollagen type IV / V
degraded collagen, elastindegraded collagen, elastin
Interstitial collagenaseInterstitial collagenase
(CL / MMP-1)(CL / MMP-1)
Interstitial collagenaseInterstitial collagenase
(CL / MMP-1)(CL / MMP-1) Fibrillar collagenFibrillar collagenFibrillar collagenFibrillar collagen
membrane-type MMP-1membrane-type MMP-1
(MT-MMP)(MT-MMP)
membrane-type MMP-1membrane-type MMP-1
(MT-MMP)(MT-MMP)
pro-MMP-2, pro-MMP-13,pro-MMP-2, pro-MMP-13,
collagen, fibronectin, laminincollagen, fibronectin, laminin
pro-MMP-2, pro-MMP-13,pro-MMP-2, pro-MMP-13,
collagen, fibronectin, laminincollagen, fibronectin, laminin
The matrix metalloproteinase (MMP)The matrix metalloproteinase (MMP)
family of enzymes can break-downfamily of enzymes can break-down
matrix componentsmatrix components
The matrix metalloproteinase (MMP)The matrix metalloproteinase (MMP)
family of enzymes can break-downfamily of enzymes can break-down
matrix componentsmatrix components
MatrilysinMatrilysin
(MMP-7)(MMP-7)
MatrilysinMatrilysin
(MMP-7)(MMP-7)
fibronectin, collagen type IV,fibronectin, collagen type IV,
laminin, elastinlaminin, elastin
fibronectin, collagen type IV,fibronectin, collagen type IV,
laminin, elastinlaminin, elastin
Could MMPs beCould MMPs be
responsible for theresponsible for the
weakening ofweakening of
atheroscleroticatherosclerotic
plaques?plaques?
211. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Galis et al. 1994, JCIGalis et al. 1994, JCI
Normal coronaryNormal coronary
arteryartery Coronary atheromaCoronary atheroma
Immunohistochemistry:Immunohistochemistry:
MMP-3MMP-3
Immuhistochemistry:Immuhistochemistry:
MMP-3MMP-3
LumenLumen
fibrous capfibrous cap
In situIn situ zymography (activity assay)zymography (activity assay)In situIn situ zymography (activity assay)zymography (activity assay)
Lysis ofLysis of
fluorescentfluorescent
substratesubstrate
First…First…
are MMPs expressed in humanare MMPs expressed in human
atheroma?atheroma?
First…First…
are MMPs expressed in humanare MMPs expressed in human
atheroma?atheroma?
The shoulders of human
atherosclerotic plaques contain
active MMPs
MMP proteins are overexpressed
in the vulnerable shoulders, but
are they enzymaticaly active ?
MMP proteins are overexpressed
in the vulnerable shoulders, but
are they enzymaticaly active ?
212. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Vulnerable plaques have a highVulnerable plaques have a high
percentage of macrophage-foam cellspercentage of macrophage-foam cells
Farb &VirmaniFarb &VirmaniFarb &VirmaniFarb &Virmani
LumenLumenMacrophagMacrophag
e foame foam
cellscells
213. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Macrophage (MMacrophage (MΦΦ) foam cells in the) foam cells in the
shoulders of human atheroma expressshoulders of human atheroma express
MMPsMMPs
Immunohistology: Detection of MMP-3Immunohistology: Detection of MMP-3 Double
immunohistology:
Detection of MMP-1 and
MΦ
Double
immunohistology:
Detection of MMP-1 and
MΦ
(Galis et al., 1994, J Clin Invest)(Galis et al., 1994, J Clin Invest)
214. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Other MMP sightings in theOther MMP sightings in the
atheroma…atheroma…
Other MMP sightings in theOther MMP sightings in the
atheroma…atheroma…
• Messenger RNA for MMP-3 colocalizes withMessenger RNA for MMP-3 colocalizes with
macrophage foam cells (Henney et al., 1991)macrophage foam cells (Henney et al., 1991)
• Active MMP-9 synthesis in atherectomyActive MMP-9 synthesis in atherectomy
specimens from patients with unstable angina andspecimens from patients with unstable angina and
MMP-13 colocalize with degraded collagen (BrownMMP-13 colocalize with degraded collagen (Brown
et al, 1995)et al, 1995)
• MMP-7 is expressed by macrophage foam cells atMMP-7 is expressed by macrophage foam cells at
sites of potential plaque rupture (Halpert et al.sites of potential plaque rupture (Halpert et al.
1996)1996)
• Macrophages can also express the elastolyticMacrophages can also express the elastolytic
MMP-8 (Herman, 2001)MMP-8 (Herman, 2001)
Macrophage foam cells are associated
with increased MMP expression and
activity
Macrophage foam cells are associated
with increased MMP expression and
activity
215. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Do MMPs degrade the collagenDo MMPs degrade the collagen
of the fibrous cap?of the fibrous cap?
Do MMPs degrade the collagenDo MMPs degrade the collagen
of the fibrous cap?of the fibrous cap?
• Macrophage MMP-2 and MMP-9 degrade exMacrophage MMP-2 and MMP-9 degrade ex
vivo the collagen of the plaque’s fibrousvivo the collagen of the plaque’s fibrous
cap (Shah et al, 1995)cap (Shah et al, 1995)
• MMP-1 and MMP-13 colocalize in theMMP-1 and MMP-13 colocalize in the
plaque with epitopes expressed byplaque with epitopes expressed by
degraded collagendegraded collagen
(immunohistochemistry, Sukhova et al,(immunohistochemistry, Sukhova et al,
1999)1999)
• MMP-8 colocalizes with epitopesMMP-8 colocalizes with epitopes
expressed by cleaved type I collagen in theexpressed by cleaved type I collagen in the
shoulders of human plaqueshoulders of human plaque
(immunohistochemistry, Herman et al.,(immunohistochemistry, Herman et al.,
2001)2001)
216. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Overexpression ofOverexpression of
interstitial collagenaseinterstitial collagenase
(MMP-1 ) coincides with the(MMP-1 ) coincides with the
places subjected to theplaces subjected to the
highest tensile stress withinhighest tensile stress within
the vulnerable shouldersthe vulnerable shoulders
(Lee(Lee et alet al. 1996). 1996)
Bad luck?!?Bad luck?!?Bad luck?!?Bad luck?!?
217. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Determinants of atherosclerotic plaqueDeterminants of atherosclerotic plaque
stabilitystability
TissueTissue
characteristicscharacteristics
MechanicalMechanical
stressstress
Active degradation of matrixActive degradation of matrix
scaffold in the vulnerablescaffold in the vulnerable
shoulders by MMPsshoulders by MMPs
(Galis(Galis et alet al 1994, Galis1994, Galis et al.et al. 1995)1995)
Tissue characteristicsTissue characteristics Mechanical stressMechanical stress
Rupture of atherosclerotic plaqueRupture of atherosclerotic plaqueRupture of atherosclerotic plaqueRupture of atherosclerotic plaque
thin fibrous capthin fibrous cap
large lipid corelarge lipid core
((Cheng et al. 1993)Cheng et al. 1993)
inflammationinflammation
((LendonLendon et al.et al.
1991, van der Wal1991, van der Wal
et alet al., 1994)., 1994)
mechanical “hotmechanical “hot
spots”coincide withspots”coincide with
the weak pointsthe weak points
((Lee et al. 1996)Lee et al. 1996)
218. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
• Cytokine stimulation: human EC (Hanemaaijeret al. 1993), human
SMC (Galis et al. 1994)
• mechanical stretch: shoulders (Lee et al, 1996)
• engagement of cell surface receptors: VCAM-1 (Romanic & Madri
1994), CD40 (Malik 1996, Schonbeck, Mach et al 1997), ICAM-1 (Aoudjit
et al 1998)
• modified lipoproteins: vascular cells (Rajavashist et al. 1999),
macrophages (Xu et al 1999)
• proteases: thrombin (Galis et al. 1995), plasmin/uPA (Carmeliet et al.
1997), cathepsins (Sukhova et al 1997), MT-MMP (Wang et al.,1998)
• oxidative stress:
• increased by superoxide, hydrogen peroxide, peroxynitrite (Rajagopalan et
al. 1996),
• Inhibited by N-acetyl cysteine (Galis et al. 1998), nitric oxide (Gurjar et
al. 1999)
• matrix composition: collagen I increases macrophage MMP(Wesley
et al. 1997)
• Infections: Chlamydia (Kol et al, 1998)Kol et al, 1998)
Potential modulators of MMP
expression and activity in atheroma
Expression of pro-
MMPs
Activation of MMP enzymatic
activity
219. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Experimental modelExperimental model
for investigation offor investigation of
macrophage foam cellmacrophage foam cell
MMPsMMPs
Subcutaneous granulomaSubcutaneous granuloma
Balloon angioplastyBalloon angioplasty
HypercholesterolemiHypercholesterolemi
c dietc diet
MacrophageMacrophage
(anti-RAM 11)(anti-RAM 11)
Intracellul
ar lipid
(Nile red)
220. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
0
200
400
600
MΦ FC
x103
counts/min/106
cells
PMA - + - +
Macrophage (MMacrophage (MΦΦ)-derived foam)-derived foam
cells (FC) producecells (FC) produce
reactive oxygen speciesreactive oxygen species
(Rajagopalan et al. 1996 JCI)(Rajagopalan et al. 1996 JCI)
Macrophage-derivedMacrophage-derived
FC activate theFC activate the
zymogen of MMP-9zymogen of MMP-9
in vitroin vitro
(Galis et al., 1998 Circulation)(Galis et al., 1998 Circulation)
Macrophage-derivedMacrophage-derived
FC activate theFC activate the
zymogen of MMP-9zymogen of MMP-9
in vitroin vitro
(Galis et al., 1998 Circulation)(Galis et al., 1998 Circulation)
SuperoxideSuperoxide
PeroxidesPeroxides
MΦMΦ FCFC
66 -66 -
97 -97 -
46 -46 -
pro-MMP-9pro-MMP-9
MMP-9MMP-9
MMΦΦ FCFC
MMP-9MMP-9
221. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Reactive oxygen species activate latentReactive oxygen species activate latent
MMPs produced by human vascular smoothMMPs produced by human vascular smooth
muscle cellsmuscle cells
++
Pro-MMP-2
Pro-MMP-9
MMP-9
MMP-2
Pro-MMP-2
MMP-2
In vivo?In vivo?In vivo?In vivo?
+ Xanthine/
Xanthine
Oxidase
+ Xanthine/
Xanthine
Oxidase
(Rajagopalan et al. 1996, JCI)(Rajagopalan et al. 1996, JCI)
222. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
N-acetyl cysteine (NAC) treatment decreasesN-acetyl cysteine (NAC) treatment decreases inin
situsitu MMP-9 expression and activity inMMP-9 expression and activity in
experimental rabbit atheromaexperimental rabbit atheroma
MMP-
9
Macrophag
es
MMP-9
+ NAC
Macrophage
s
+ NAC100100
µµmm
IELIEL
Pro-MMP-2 -
MWM
(kDa)
Abdomina
l aorta
Thoracic
aorta
+ NAC + NAC0 0
MMP-2 -
Pro-MMP-9 -
MMP-9 -
(Galis et al., 1998 Circulation)(Galis et al., 1998 Circulation)
223. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Lipid lowering therapy mayLipid lowering therapy may
increase plaque stability byincrease plaque stability by
decreasing the oxidative stressdecreasing the oxidative stress
•improvement ofimprovement of
endothelial functionendothelial function
•decreased plaque lipiddecreased plaque lipid
•decreased MMPdecreased MMP
productionproduction
increased plaqueincreased plaque
stabilitystability
•improvement ofimprovement of
endothelial functionendothelial function
•decreased MMPdecreased MMP
productionproduction
increased plaqueincreased plaque
stabilitystability
OxidativOxidativ
e stresse stress
LipidLipid
herapeutic interventions and plaque stabiliherapeutic interventions and plaque stabilitherapeutic interventions and plaque stabilitherapeutic interventions and plaque stabilit
224. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Experimental macrophage-rich arterialExperimental macrophage-rich arterial
lesions (ApoE KO mouse carotid arterylesions (ApoE KO mouse carotid artery
ligation)ligation)
Macrophage-Macrophage-
rich neointimarich neointima
Normal carotidNormal carotid
arteryartery
Normal carotidNormal carotid
arteryartery
Atherosclerotic carotidAtherosclerotic carotid
arteryartery
Atherosclerotic carotidAtherosclerotic carotid
arteryartery
(Lessner et al.,(Lessner et al.,
unpublished)unpublished)
225. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Our studies indicate that arteries withOur studies indicate that arteries with
macrophage-rich lesions undergomacrophage-rich lesions undergo
enhanced positive remodelingenhanced positive remodeling
Our studies indicate that arteries withOur studies indicate that arteries with
macrophage-rich lesions undergomacrophage-rich lesions undergo
enhanced positive remodelingenhanced positive remodeling
55 1010 11
55
2020 2525 303055 1010 11
55
2020 2525 3030
Macrophage areaMacrophage area
10001000
20002000
Outer perimeterOuter perimeter
Time
(days)
Time
(days)
1010
2020
3030
4040
AreaArea
((µµmm22
))
LengtLengt
h (h (µµm)m)
- -
Pro MMP-9
Pro MMP-2
98 kDa
72 kDa
- -
Days 0 14 2
8
WT W
T
WTKO KO KOS
T
Arteries with macrophage-rich lesions
have enhanced MMP activity
Arteries with macrophage-rich lesions
have enhanced MMP activity
226. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Positively remodeling isPositively remodeling is
associated with plaqueassociated with plaque
instabilityinstability
Positively remodeling isPositively remodeling is
associated with plaqueassociated with plaque
instabilityinstability
Schoenhagen et al., 2000 Circulation 101Schoenhagen et al., 2000 Circulation 101Schoenhagen et al., 2000 Circulation 101Schoenhagen et al., 2000 Circulation 101
UnstableUnstable
StableStable
PositivePositive NegativeNegativeAbsentAbsent
2020
3030
4040
5050
1010
RemodelingRemodeling
%cohort%cohort
227. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
FoamFoam
cell/macrophagcell/macrophag
e-drivene-driven
SmoothSmooth
muscle cell-muscle cell-
drivendriven
UnstablUnstabl
ee
plaqueplaque
StableStable
plaqueplaque
Constrictive arterial remodelingConstrictive arterial remodeling
Outward arterial remodelingOutward arterial remodeling(Galis and(Galis and
Khatri,Khatri,
2002)2002)
Normal arteryNormal artery
228. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Macrophage-foam cells are key
regulators of MMP-dependent
degradation of vascular matrix
Macrophage-foam cells are key
regulators of MMP-dependent
degradation of vascular matrix
ROSROS
TFTF
ThrombinThrombin
ModulateModulate
MMPMMP
activityactivity
ExpressExpress
pro-pro-
MMPsMMPs
CytokinesCytokines
UpregulateUpregulate
vascularvascular
cell MMPscell MMPs
Macrophage foam cellsMacrophage foam cells
229. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Macrophage non-MMPMacrophage non-MMP
proteases?proteases?
Macrophage non-MMPMacrophage non-MMP
proteases?proteases?
• CathepsinsCathepsins K and S
– have elastolytic activityhave elastolytic activity
– Expressed by macrophages in atheromaExpressed by macrophages in atheroma
(Sukhova et al. 1998)(Sukhova et al. 1998)
• ThrombinThrombin
– generated at sites of disruption, can begenerated at sites of disruption, can be
generated in the atherosclerotic plaques viagenerated in the atherosclerotic plaques via
tissue factor expressed by macrophage foamtissue factor expressed by macrophage foam
cells (Wilcox et al. 1989)cells (Wilcox et al. 1989)
– can activate latent MMP-2 (Galis et al., 1997)can activate latent MMP-2 (Galis et al., 1997)
230. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Potential protease networksPotential protease networksPotential protease networksPotential protease networks
• Macrophage MMPs may increase the activity ofMacrophage MMPs may increase the activity of
other proteases through:other proteases through:
– Activation of MMP zymogens - e.g., MMP-3 can activateActivation of MMP zymogens - e.g., MMP-3 can activate
pro-MMP-1pro-MMP-1
– inactivation of inhibitors - e.g., MMP-1, MMP-3, and MMP-inactivation of inhibitors - e.g., MMP-1, MMP-3, and MMP-
9can inactivate alpha 1-antitrypsin, the primary9can inactivate alpha 1-antitrypsin, the primary
physiologic inhibitor of human leukocyte elastase (Siresphysiologic inhibitor of human leukocyte elastase (Sires
et al. 1994et al. 1994); MMP-1, MMP-7, MMP-9, and MMP-12 cleave); MMP-1, MMP-7, MMP-9, and MMP-12 cleave
tissue factor pathway inhibitor (Belaaouaj et al, 2000)tissue factor pathway inhibitor (Belaaouaj et al, 2000)
• Macrophage non-MMPs may increase theMacrophage non-MMPs may increase the
activity of other proteases through:activity of other proteases through:
– Activation of MMP zymogens -- e.g., uPA can activate pro-Activation of MMP zymogens -- e.g., uPA can activate pro-
MMP-3, thrombin can activate pro-MMP-2MMP-3, thrombin can activate pro-MMP-2
– inactivation of inhibitors ?inactivation of inhibitors ?
231. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
RupturedRuptured
plaqueplaque
The mutual stimulation of generation ofThe mutual stimulation of generation of
active MMPs and thrombin may the basisactive MMPs and thrombin may the basis
of sustained plaque instability, withof sustained plaque instability, with
recurring episodes of plaque disruptionrecurring episodes of plaque disruption
and thrombosisand thrombosis
MMPsMMPs
ThrombinThrombin
MMPsMMPs
ThrombinThrombin
ThrombinThrombin
activatesactivates
latent MMPslatent MMPs
(Galis et al.,(Galis et al.,
1997)1997)
ActiveActive
MMPsMMPs
stimulatestimulate
generationgeneration
of thrombinof thrombin
(Sawicki et(Sawicki et
al., 1997)al., 1997)
roteases and the unstable atherosclerotic plaquroteases and the unstable atherosclerotic plaquroteases and the unstable atherosclerotic plaquroteases and the unstable atherosclerotic plaqu
232. Content and GraphicsContent and Graphics
Zorina Galis, Ph.D.Zorina Galis, Ph.D.
Are these proteasesAre these proteases
redundant?redundant?
What are the potential actionsWhat are the potential actions
of all these in relation toof all these in relation to
plaque rupture?plaque rupture?
Are these proteasesAre these proteases
redundant?redundant?
What are the potential actionsWhat are the potential actions
of all these in relation toof all these in relation to
plaque rupture?plaque rupture?• MMPs can degrade all the components of theMMPs can degrade all the components of the
extracellular matrixextracellular matrix
• uPAuPA activatesactivates MMP zymogens (MMP zymogens (Carmeliet et al. 1997)
• Thrombin can activate MMP zymogens (Galis et al.Thrombin can activate MMP zymogens (Galis et al.
1997)1997)
Do MMPs provide a common pathway forDo MMPs provide a common pathway for
plaque weakening by other proteases?!?plaque weakening by other proteases?!?
Do MMPs provide a common pathway forDo MMPs provide a common pathway for
plaque weakening by other proteases?!?plaque weakening by other proteases?!?