Myeloperoxidase and Cardiovascular Disease
Stephen J. Nicholls and Stanley L. Hazen
Arterioscler Thromb Vasc Biol. 2005;25:1102-1111; originally published online March 24,
2005;
doi: 10.1161/01.ATV.0000163262.83456.6d
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Myeloperoxidase and Cardiovascular Disease
Stephen J. Nicholls, Stanley L. Hazen
Abstract—Myeloperoxidase (MPO) is a leukocyte-derived enzyme that catalyzes the formation of a number of reactive
oxidant species. In addition to being an integral component of the innate immune response, evidence has emerged that
MPO-derived oxidants contribute to tissue damage during inflammation. MPO-catalyzed reactions have been attributed
to potentially proatherogenic biological activities throughout the evolution of cardiovascular disease, including during
initiation, propagation, and acute complication phases of the atherosclerotic process. As a result, MPO and its
downstream inflammatory pathways represent attractive targets for both prognostication and therapeutic intervention in
the prophylaxis of atherosclerotic cardiovascular disease. (Arterioscler Thromb Vasc Biol. 2005;25:1102-1111.)
Key Words: atherosclerosis 䡲 free radical 䡲 heart failure 䡲 high-density lipoprotein 䡲 low-density lipoprotein
䡲 myeloperoxidase 䡲 nitric oxide 䡲 scavenger receptor 䡲 vulnerable plaque
I
nflammatory events have been implicated at all stages in
the evolution of atherosclerotic plaque, from the early
development of endothelial dysfunction, through to formation
of the mature atheroma and its subsequent rupture.1 Elucidation of the factors that coordinate this complex cascade has
assumed increasing importance in the search to identify
accurate predictors of cardiovascular risk and targets for
therapeutic intervention.
Myeloperoxidase (MPO) has emerged as a potential participant in the promotion and/or propagation of atherosclerosis. A member of the heme peroxidase superfamily, MPO
generates numerous reactive oxidants and diffusible radical
species2 that are capable of both initiating lipid peroxidation3,4 and promoting an array of post-translational modifications to target proteins, including halogenation, nitration, and
oxidative cross-linking.5,6 MPO, the most abundant component of azurophilic granules of leukocytes, is secreted on
leukocyte activation, contributing to innate host defenses.2,7
Found predominantly in neutrophils,8 monocytes,9 and some
subtypes of tissue macrophages,10 –12 MPO amplifies the
oxidative potential of its cosubstrate hydrogen peroxide,
forming potent oxidants capable of chlorinating and nitrating
phenolic compounds.3,5,6,13 The hydrogen peroxide substrate
may be derived from a number of sources in vivo, including
leukocyte NADPH oxidases, xanthine oxidase, uncoupled
nitric oxide synthase (NOS), and various Nox isoenzymes.14,15 MPO is unique in its ability to generate reactive
chlorinating species such as hypochlorous acid (HOCl),16 the
active component of bleach, which possesses potent bactericidal and viricidal activities.17,18 In addition, HOCl reacts
with electron-rich moieties of a large range of biomolecules.5
The essential role of MPO as a component of the innate
immune response to foreign invasion was first recognized
nearly 4 decades ago.17,18 The past decade has witnessed a
resurgence in research efforts focusing on this unique heme
protein. Spurred initially by the recognition that MPO is
enriched within human atheroma,10 both MPO and its reactive
oxidants have been implicated as participants in tissue injury
Original received January 23, 2005; final version accepted March 7, 2005.
From the Departments of Cardiovascular Medicine and Cell Biology and Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic
Foundation, Cleveland, Ohio.
Correspondence to Stanley L. Hazen, MD, PhD, Cleveland Clinic Foundation, Lerner Research Institute, Center for Cardiovascular Diagnostics and
Prevention, 9500 Euclid Avenue, NC-10, Cleveland, OH 44195. E-mail [email protected]
© 2005 American Heart Association, Inc.
Arterioscler Thromb Vasc Biol. is available at http://www.atvbaha.org
DOI: 10.1161/01.ATV.0000163262.83456.6d
1102
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Nicholls and Hazen
during a large number of inflammatory conditions.3– 6,19 –21 In
this review, evidence linking MPO and its oxidative pathways
with the initiation, propagation, and both acute and chronic
complications of atherosclerotic cardiovascular disease
(CVD) are highlighted.
Myeloperoxidase and Cardiovascular Disease
The Human Experience
Multiple lines of evidence suggest that MPO may play a role
in atherogenesis in humans. Immunohistochemical and biochemical analyses localize the enzyme and its oxidation
products within human atherosclerotic lesions.10,12,22–25 Individuals with total or subtotal MPO deficiency, a defect with
a frequency of ⬇1 in every 2000 to 4000 whites, appear less
likely to have CVD develop.26 Further, individuals harboring
a promoter polymorphism associated with a reported 2-fold
reduction in MPO expression appear cardioprotected, with
markedly reduced angiographic evidence of coronary artery
disease, nonfatal myocardial infarction, and cardiac
death.27–30 Increasing systemic levels of MPO have also been
demonstrated to predict the presence of angiographic coronary artery disease.31 Individuals who possess MPO levels in
the fourth quartile among sequential subjects undergoing
diagnostic cardiac catheterization at a tertiary referral center
were 15- to 20-fold more likely to demonstrate abnormal
coronary angiograms (defined as ⬎50% stenosis in one or
more major coronary arteries) compared with subjects in the
lowest quartile. This relationship remained significant after
statistical adjustments for Framingham risk score and
C-reactive protein. In addition, plasma and serum levels of
MPO have been shown to predict risks of subsequent major
adverse cardiac events (nonfatal myocardial infarction, death,
and need for revascularization) in patients presenting with
either chest pain32 or acute coronary syndromes.33 Thus,
numerous biochemical and genetic studies in humans demonstrate strong and independent relationships between MPO
and CVD risks.
The Mouse Experience
In contrast, data from animal studies of atherosclerosis have
failed to demonstrate such relationships. When low-density
lipoprotein (LDL) receptor knockout mice underwent irradiation
and subsequent infusion of bone marrow from MPO knockout
mice, the extent of atherosclerotic lesions actually modestly
increased.34 Similarly, no significant impact of the MPO-null
genotype on atherosclerosis development was observed in the
atherosclerosis prone apolipoprotein E–null background mouse
model.34 At first glance, these results suggested that MPO has
little role, or may even be atheroprotective, in the murine
atherosclerosis model. However, on further inspection, it was
highlighted that atherosclerotic lesions in both LDL receptor–
null and apolipoprotein E–null mouse models are virtually
devoid of any trace of either MPO or its specific oxidation
product, chlorotyrosine.34 Moreover, murine leukocytes were
found to carry 10- to 20-fold less MPO per cell compared with
corresponding human leukocyte types.
These findings highlight a clear species difference between
human and murine atherosclerosis. This has led to the
conclusion that common mouse models of atherosclerosis
Myeloperoxidase and Vascular Disease
1103
may not permit investigation of the potential involvement of
MPO in human atherogenesis.35 Although murine atherosclerosis models to date have yet to demonstrate the presence of
MPO or its catalytic activity within the target organ/tissue (ie,
arterial tissues), it is notable that more acute inflammation
models in mice (ie, those with clear neutrophil involvement)
demonstrate both the presence of MPO and its oxidation
products. Murine models in which both MPO and its oxidative products are observed have been used to support a key
role for the enzyme in promotion of lipid peroxidation,
protein nitration and other oxidative modifications, endothelial dysfunction, and adverse ventricular remodeling in the
setting of acute myocardial infarction, as discussed.3,36 –39
Potential Mechanisms for Myeloperoxidase
Contributing to the Promotion of Vascular Disease
A role for MPO throughout the evolution of the atherosclerotic process has been supported by numerous investigations
(Figure 1). As described herein, mechanistic links exist
between MPO and the generation of atherogenic lipoproteins,
consumption of nitric oxide (NO) and development of endothelial dysfunction, initiation and propagation of the mature
atheroma and its subsequent complications of plaque rupture,
thrombosis, and ventricular remodeling.
Myeloperoxidase Converts LDL Into an
Atherogenic Form
Population studies have consistently demonstrated that the incidence of CVD correlates directly with circulating concentrations
of LDL.40 Similarly, therapeutic interventions that reduce systemic levels of LDL are associated with a marked atheroprotective benefit.41– 45 Despite these relationships, a role for native
LDL in cholesterol accumulation within cells of the artery wall
has proven difficult to demonstrate, because replete intracellular
stores of cholesterol trigger downregulation of the LDL receptor
and inhibition in the rate limiting step in de novo cholesterol
synthesis, 3-hydroxy-3-methylglutaryl coenzyme A reductase.46,47 Rather, LDL that has undergone modification, predominantly by oxidation, appears to play a central role in promoting
the atherogenic processes, such as cholesterol accumulation
through recognition by scavenger receptors. LDL that accumulates in the subendothelial space may become modified, such as
through oxidation and glycation and subsequently taken up by
macrophages to become foam cells, the first cellular hallmark of
the atherosclerotic plaque.48 Immunohistochemical studies have
demonstrated the presence of oxidized LDL in atherosclerotic
lesions.49 Oxidized LDL is cytotoxic50 and circulating levels of
antibodies directed against oxidized LDL correlate with the
presence of CVD.51 In addition, immunization against oxidized
LDL is atheroprotective in animal models.52 Despite the overwhelming evidence supporting a pathogenic role for oxidative
processes in atherogenesis, elucidation of the precise pathways
that modify LDL in vivo proved difficult to demonstrate given
the fact that most oxidation products may be generated by
multiple distinct pathways and are thus noninformative with
respect to the mechanisms of their formation.
Use of quantitative analytic methods to identify structurally
defined molecular markers for distinct oxidative processes has
provided valuable mechanistic insights into the role of MPO and
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Arterioscler Thromb Vasc Biol.
June 2005
Figure 1. Scheme illustrating multiple
processes throughout the evolution of
atherosclerosis in which MPO is implicated. MPO has been linked to events
that participate in the initiation and progression of plaque formation including
lipid peroxidation, generation of atherogenic lipoproteins and dysfunctional
HDL, and catalytic consumption of nitric
oxide (NO). MPO may thus contribute to
endothelial dysfunction, leukocyte transmigration, and accumulation of foam
cells. MPO may participate in ischemic
complications of atherosclerosis via activation of protease cascades and promotion of endothelial cell (EC) apoptosis,
leading to breakdown of the fibrous cap.
Mechanistic links with activation of tissue
factor (TF) and the coagulation cascade
are also reported. Studies with MPO
knockout mice and models of myocardial
infarction have supported a role for the
heme protein in progression of myocardial necrosis to adverse ventricular
remodeling and heart failure via its ability
to activate proteases and promote degradation of the extracellular matrix.
its derived oxidants in the conversion of LDL into an atherogenic form within human atheroma. Mass spectrometry and
immunohistochemical studies demonstrate that MPO is catalytically active within human atheroma because chlorotyrosine, a
specific product of protein modification by MPO-generated
halogenating oxidants, is enriched within human atherosclerotic
lesions compared to normal arterial intima.22 More recent studies
demonstrate marked enrichment of bioactive chlorinated lipid
oxidation products within human atheroma as well.23 Additionally, alternative oxidation products which may be generated by
MPO, as well as other pathways, such as nitrotyrosine (a
post-translational modification generated by reactive nitrogen
species) and dityrosine (an oxidative crosslink formed by tyrosyl
radical–mediated pathways), are similarly enriched within human atheroma.22,24,53,54 In addition, LDL isolated from human
atheroma contains greater amounts of these products than
circulating LDL from healthy controls.22,53 Thus, multiple lines
of evidence confirm a role for MPO as a catalyst for oxidant
generation within the artery wall in CVD subjects.
Multiple lines of evidence suggest that proatherogenic
biological consequences may be triggered by oxidative modification of targets in the artery wall by MPO-generated
reactive species. Lipid oxidation products of plasmalogens
generated by the MPO-derived oxidant HOCl are both enriched within human atheroma and possess potent leukocyte
chemotactic activity.23 Incubation of HOCl and LDL results
in oxidation of lysine residues in apolipoprotein B-100, the
predominant protein of LDL.55 Increasing anionic surface
charge, as well as HOCl-induced lipoprotein aggregation,
both convert LDL into a high-uptake form, and appear to
occur within human atheroma.56 Under physiological conditions, activated human monocytes also use MPO-generated
reactive nitrogen species to render LDL atherogenic, converting it into a high-uptake form for macrophages,57 while
simultaneously promoting both apolipoprotein B-100 protein
nitration and initiation of LDL lipid peroxidation58 (Figure 2).
The oxidized form of LDL generated, termed “NO2LDL,” has
since been demonstrated to be selectively recognized by the
scavenger receptor CD36,59 a major participant in fatty streak
and atherosclerotic lesion development.60 Detailed subsequent studies using biochemical, mass spectrometry and
chemical synthesis have identified a novel family of oxidized
phospholipids that serve as high affinity ligands for the
macrophage scavenger receptor CD36 on both NO2LDL and
other forms of oxidized LDL,61 as well as documented their
enrichment within atherosclerotic lesions (Figure 2).62
A central role for MPO as a physiological catalyst for
initiation of lipid peroxidation in vivo has been established using
neutrophils isolated from humans with MPO deficiency versus
normal subjects and subsequently activated within plasma.4
Studies with MPO knockout mice also confirm a dominant role
for MPO in the initiation of lipid peroxidation at sites of acute
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Nicholls and Hazen
Myeloperoxidase and Vascular Disease
1105
Figure 3. MPO-catalyzed site-specific apolipoprotein A-I chlorination and the impairment of ABCA-1–mediated reverse cholesterol transport activity. Exposure of HDL to either the MPO/
H2O2/Cl⫺ system or HOCl results in dose-dependent loss of
ABCA-1– dependent reverse cholesterol efflux activity of HDL
(A). Parallel site-specific quantitation of apolipoprotein A-I chlorination using LC/ESI/MS/MS reveals comparable dosedependent losses of the MPO-binding peptides (B). Mass spectrometry studies demonstrate the same sites are modified in
apolipoprotein A-I recovered from human plaque. Reprinted with
permission from Zheng et al.74
Figure 2. MPO-generated reactive nitrogen species render LDL
atherogenic. Human monocytes use the MPO-H2O2-nitrite (NO2⫺)
system to form nitrogen dioxide (䡠NO2), an NO-derived oxidant,
which promotes protein nitration, lipid peroxidation, and conversion
of LDL into a high-uptake form of oxidized LDL (oxLDL), NO2LDL,
for the scavenger receptor CD36. CD36 plays a critical role in formation of foam cells, fatty streaks, and atherosclerotic plaque in
vivo. A novel family of ␣,␤ unsaturated ␥-hydroxy (or oxo)-sn-2
tethered glycerophospholipids have been identified as high-affinity
ligands for CD36 on oxidized forms of LDL, including NO2LDL.
Adapted from references 4 and 57 to 60. Reprinted with permission from the cover of J Biol Chem, October 11, 2002.61,62
inflammation, because ⬎75% of the F2-isoprostanes and other
bioactive eicosanoids formed are attributable to MPO as the
source.3 Similarly, a role of MPO as a catalyst of extracellular
protein nitration, such as at some sites of inflammation, is
supported by studies using MPO knockout mice.36,39 It is thus
significant that recent clinical studies demonstrate protein-bound
nitrotyrosine predicts atherosclerotic risk and burden and is
modulated by atorvastatin therapy.63
Myeloperoxidase Selectively Modifies
Apolipoprotein A-I, Generating Dysfunctional
High-Density Lipoprotein
High-density lipoprotein (HDL) particles are the major carriers
of lipid hydroperoxides in circulating plasma.64 The enzymatic
source of these lipid hydroperoxides, however, is unknown. In
vitro studies of HDL oxidation have been reported to have either
a beneficial,65,66 neutral,67 or detrimental68 –72 impact on the
ability of HDL to promote cellular cholesterol efflux. However,
it remained to be determined whether physiologically relevant
oxidative modifications of HDL influence the atheroprotective
properties of the lipoprotein particle, and the precise oxidative
pathways that modify HDL within the diseased artery wall.
Recent evidence has emerged to identify HDL as a target for
site-specific modification by MPO-derived oxidants in the artery
wall with concomitant functional impairment.
A role for MPO in the oxidative modification of HDL in vivo,
with consequent functional inactivation, has been supported by
results from several groups. HDL isolated from atherosclerotic
lesions contain numerous MPO-derived peptides, including
site-specific oxidative modifications by reactive chlorinating and
nitrating species.73,74 Moreover, HDL isolated from human
atheroma contains MPO, consistent with the recent finding that
MPO selectively binds to apolipoprotein A-I within plasma via
a specific region on helix 8 of the lipoprotein.73 Analysis of
apolipoprotein A-I isolated from plasma of subjects with CVD
versus that from healthy controls reveals that a greater content of
nitrotyrosine (NO2Tyr) and chlorotyrosine (ClTyr) per apolipoprotein A-I particle are observed within subjects with CVD.73,75
The degree of this modification was found to correlate with the
frequency of coronary artery disease and CVD,73 findings that
have now been independently confirmed.75,76 Examination of
nearly 100 sequential subjects to an outpatient preventive cardiology clinic revealed that patients harboring the highest tertile of
apolipoprotein A-I NO2Tyr and ClTyr content were 6- and
16-fold more likely to have CVD than those in the respective
lowest tertile.73 Moreover, apolipoprotein A-I isolated from
atherosclerotic plaque demonstrates a much greater degree of
modification (by several orders of magnitude) than a typical
protein within plasma or atherosclerotic plaque, with up to 1 of
every 2 HDL particles recovered from human atherosclerotic
lesions bearing a ClTyr or NO2Tyr modification in some
subjects.73 These results suggest that MPO-catalyzed oxidation
of apolipoprotein A-I preferentially occurs in the arterial wall.
Consistent with this finding, immunohistochemical analysis of
human atheroma specimens reveals MPO- and HOCl-modified
proteins colocalize with apolipoprotein A-I in the region of
macrophages.56,77
Using tandem mass spectrometric techniques, specific sites
on apolipoprotein A-I have been identified as the preferred
targets for modification by MPO-derived oxidants, with
associated functional impairment of the lipoprotein.74 Residues on helix 8 (eg, Tyr 192) appear to be the predominant
site of MPO-catalyzed oxidation in vitro and within human
atheroma and colocalize with the MPO-binding site identified
on apolipoprotein A-I within HDL.73,74 Remarkably, the
degree of site-specific modification of apolipoprotein A-I and
enrichment of apolipoprotein A-I with NO2Tyr and ClTyr are
each associated with a reduction in the ability of apolipoprotein A-I to promote ABCA-1– dependent cholesterol efflux in
vitro and in vivo (Figure 3),73,74 findings which have been
independently confirmed.75 In vitro studies also demonstrate
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Arterioscler Thromb Vasc Biol.
June 2005
that HDL exposed to the MPO-generated oxidant HOCl
competes with unmodified HDL as a ligand for the scavenger
receptor BI, suggesting that MPO-generated oxidants may
interfere with the normal interaction of apolipoprotein A-I
with scavenger receptor BI, a key step in the promotion of
cholesterol efflux.72
A major determinant of plaque progression or regression
rate is the balance between cholesterol uptake versus efflux
pathways. These results suggest that MPO may adversely
impact on both processes, fostering the net deposition and
accumulation of cholesterol within cells of the artery wall.
The correlation between MPO levels and angiographic evidence of atherosclerotic plaque,31 as well as the apparent
atheroprotective effects of genetic deficiencies of MPO,26 –30
are consistent with the hypothesis that MPO participates in
the initiation and/or propagation of CVD (Figure 1). Studies
directly assessing systemic levels of MPO in parallel to
quantitative indices of human atherosclerotic plaque volume
will be both informative and of potential prognostic
relevance.
Myeloperoxidase Promotes
Endothelial Dysfunction
Dysfunction of the endothelial cell layer is one of the earliest
changes of atherogenesis.1 This state is characterized by the
development of abnormal vascular reactivity and expression
of various proinflammatory and prothrombotic factors. A key
factor promoting endothelial dysfunction involves a reduced
bioavailability of NO.78,79 Abnormal vascular reactivity has
been demonstrated in patients with both cardiovascular risk
factors80 and with established coronary heart disease.81 Further, numerous therapeutic interventions with a proven
atheroprotective benefit have been demonstrated to improve
vascular reactivity.82
Recent studies strongly suggest a direct role for MPO as a
participant in the development of endothelial dysfunction
through limitation in NO bioavailability. Although a potential
role of NO as a cosubstrate for prostaglandin H synthase had
been suggested,83 it had yet be investigated as a potential
substrate for leukocyte heme peroxidases like MPO until the
first report by Abu-Soud and Hazen.84 Given the colocalization of MPO within atherosclerotic plaque, a direct role for
the enzyme in promoting endothelial dysfunction via consumption of NO has subsequently been explored by several
groups. MPO-generated oxidants have been reported capable
of inhibiting the activity of NOS. Chlorination of arginine
following reaction with HOCl reduces its substrate availability and directly inhibits enzymatic activity of NOS, reducing
the in vitro formation of NO metabolites by endothelial cells,
and subsequent acetylcholine-induced relaxation of rat aortic
ring segments.85,86 Reactive nitrogen species such as those
generated by MPO have also been shown to uncouple NOS.87
NO synthesis is further inhibited by HDL modified by a
MPO-generated chlorinating system, which results in delocalization of endothelial NOS from its normal plasma membrane location.88 Further, MPO and HOCl both reduce the
availability of NADPH, an essential NOS cofactor.89 A
combination of both direct catalytic consumption, radical–
radical scavenging effects, and modulation of NOS activity
through oxidation of its substrates and cofactors all likely
contribute to the observations that MPO inhibits NOdependent dilatation of preconstricted arterial37,86 and tracheal segments.90
Direct in vivo support for MPO as a catalytic sink for NO
is supported by studies in murine models. Arterial segment
NO-dependent relaxation was shown to be reduced after
endotoxin administration in wild-type relative to MPO
knockout mice.37 The demonstrations that MPO avidly binds
to endothelial cells and is subsequently transcytosed to the
subendothelial space,39 the compartment where immunohistochemical studies localize both MPO and nitrotyrosine,91
further suggests that MPO is anatomically positioned between endothelial cells and their target smooth muscle cells to
intercept NO and limit its bioavailability.
Experimental data implicating a role for MPO in the
development of endothelial dysfunction have recently been
extended to humans. Vita et al demonstrated that serum MPO
levels independently predict the prevalence of endothelial
dysfunction in a cohort of 298 subjects.92 A strong inverse
correlation was observed between MPO levels and flowmediated dilatation of the brachial artery. After adjusting for
the presence of traditional cardiovascular risk factors, medications, and prevalent CVD, MPO remained a robust predictor of endothelial dysfunction, with individuals possessing
fourth-quartile MPO levels remaining 6.4-fold more likely to
demonstrate endothelial dysfunction compared with subjects
with MPO levels in the lowest quartile. Similarly, MPO has
recently been shown to enhance NO catabolism during
myocardial ischemia and reperfusion.93 Myocardial tissues
from patients presenting with acute myocardial infarction
were shown to demonstrate intense recruitment of MPOpositive neutrophils localized along infarct-related vessels, as
well as diffuse endothelial distribution of free MPO immunoreactivity. Parallel endothelium-dependent microvascular
function studies demonstrated that forearm blood flow in
patients with symptomatic coronary artery disease was
strongly and inversely correlated with MPO plasma levels
(r⫽⫺0.75, P⬍0.005). Thus, kinetic, cellular, animal model,
and human clinical studies all point toward a role for MPO as
a major enzymatic sink for NO within diseased coronary
vessels.
Myeloperoxidase and Development of
Vulnerable Plaque
The majority of clinical ischemic events result from the
breakdown of the fibrous cap overlying the atherosclerotic
plaque.94 Pathological studies have established that culprit
lesions are typically macrophage rich atheroma containing
large amounts of matrix metalloproteinases and prothrombotic material.95,96 These plaques are more likely to undergo
thinning and subsequent breakdown of the overlying fibrous
cap. This exposes circulating blood to the plaque’s thrombogenic core, resulting in thrombus formation, luminal compromise, and ischemia (Figure 1). Factors that promote the
inflammatory cascade in atherosclerotic plaque are likely to
be associated with the development of clinical ischemia.
The ability of systemic MPO levels to predict the likelihood of clinical events suggests that MPO plays a role in the
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Nicholls and Hazen
transition of a mature atherosclerotic plaque to the vulnerable
state. Brennan et al demonstrated the prognostic value of
plasma MPO levels in a cohort of 604 sequential patients
presenting to the emergency department with chest pain.32
Subjects in the highest MPO quartile had a 3.9-fold higher
likelihood of having a myocardial infarction on presentation
and were 4.7-fold more likely to have a major adverse cardiac
event in the ensuing 30 days and 6 months. Remarkably, this
relationship was observed both in the presence and absence of
biochemical evidence of myocardial necrosis. The predictive
value of MPO over the ensuing 6-month period exceeded that
of other established biomarkers including troponin T, CKMB, and C-reactive protein. In a similar fashion, Baldus et al
found that serum MPO was an independent predictor of
adverse cardiac outcomes at 30 days and 6 months in patients
with acute coronary syndromes participating in the CAPTURE study.33 Patients with MPO levels in the top tertile
were ⬇3 times more likely to experience death or nonfatal
myocardial infarction within 72 hours of enrollment compared with patients in the lowest MPO tertile. The ability of
serum MPO levels obtained at the time of subject randomization to predict adverse outcomes over the past 6 months
was independent of other prognostic markers, including
troponin, C-reactive protein, and soluble CD40 ligand.33
Acute coronary syndromes are characterized by evidence
of leukocyte activation. Pathological studies have localized
both a marked infiltration of neutrophils97 and colocalization
of MPO- and HOCl-modified proteins with macrophages in
culprit lesions associated with intracoronary thrombi.12 In
addition, unstable angina is characterized by an increase in
the expression of leukocyte activation markers,98 as well as
the presence of a transcoronary reduction in intracellular
leukocyte MPO staining, consistent with systemic leukocyte
activation.99 Further studies have demonstrated potential
mechanisms by which MPO may promote plaque instability.
MPO-derived oxidants colocalize with macrophages and the
latent form of matrix metalloproteinase-7 in atherosclerotic
lesions.100 In vitro studies demonstrate that HOCl promotes
the activation of latent matrix metalloproteinase-7 via oxygenation of a thiol residue in the enzyme’s cysteine switch.100
This molecular switch provides a mechanistic rationale for
the demonstration 2 decades ago by Weiss et al that neutrophils release and activate gelatinase by a HOCl-dependent
process.101 This process appears to be under dynamic control
because oxidative modification of tryptophan and glycine
residues in the catalytic domain of matrix metalloproteinase-7
serve as a potential mechanism for restraining proteolytic
activity during inflammation.102
Libby et al recently reported that MPO-generated HOCl
may contribute to intracoronary endothelial cell desquamation and the engenderment of a prothrombotic phenotype.
Physiologically relevant levels of HOCl were shown to
promote endothelial cell apoptosis and detachment of endothelial cells in vitro.103 MPO-triggered endothelial cell apoptosis has been suggested as a mechanism for development of
superficial erosions, the apparent inciting event in intracoronary thrombus formation in more than one-quarter of acute
coronary syndromes, with particular prevalence in women
and smokers.104 Interestingly, MPO levels in women appear
Myeloperoxidase and Vascular Disease
1107
to exhibit a trend toward being a stronger predictor of clinical
events,105 and estradiol has recently been identified as a
potential endogenous substrate for MPO-catalyzed lipid peroxidation.4 Whether these observations provide a mechanistic
link for the observation that superficial plaque erosions are
more commonly observed in females, and are enriched with
MPO, remains to be established.106
Several lines of evidence suggest that MPO may also increase
the propensity to thrombus formation in the setting of plaque
instability. The appearance of detached apoptotic cells in the
systemic circulation is a potential stimulus for platelet activation
and aggregation.107 The ability of MPO to reduce NO bioavailability renders the normally antithrombotic endothelial surface
thrombogenic via the expression of various prothombotic and
antifibrinolytic factors.108 In addition, MPO-derived lipid oxidation products enriched in atheroma activate endothelial cells,
promoting the surface expression of P-selectin, favoring platelet
adhesion.23 Incubation of endothelial cells with low doses of
MPO, or MPO-expressing macrophages, results in increased
expression and activity of tissue factor.103 Latent tissue factor
pathway activity is also activated by lipid hydroperoxides,109,110
which are generated by the activity of MPO in vivo.3,4
MPO Promotes Myocardial Dysfunction and
Abnormal Ventricular Remodeling After
Myocardial Infarction
Inflammation continues to play a central role in the pathological events that occur after rupture of the fibrous cap and
luminal occlusion. Leukocyte migration to peri-necrotic
zones and reperfusion of an occluded artery exposes the
ischemic territory to further inflammatory and oxidative
stresses. It remains to be determined whether the increase in
MPO activity that accompanies models of ischemia reperfusion injury contributes to the resulting tissue damage and
infarct extension.111 However, recent studies have demonstrated that MPO contributes to adverse ventricular remodeling after myocardial infarction. Using a chronic coronary
artery ligation model, MPO knockout mice demonstrated a
marked reduction in leukocyte infiltration and left ventricular
dilatation, associated with delayed myocardial rupture and
preservation of systolic function (Figure 4).38 This benefit
was associated with reductions in the oxidative inactivation
of plasminogen activator inhibitor-1 and subsequent tissue
plasmin activity. By promoting the development of abnormal
ventricular geometry, MPO may thus play a role in the
susceptibility to and progression of heart failure after myocardial infarction.
Development of MPO-Targeted
Therapeutic Interventions
The many links between MPO and proatherogenic activities
that might participate in many stages of cardiovascular
disease has stimulated considerable interest in the development of therapeutic strategies to inhibit MPO catalysis. One
potential difficulty with development of an MPO inhibitor is
the concern that such a drug might have adverse effects
related to impairment in the role of enzymes in innate host
defenses. It should be noted, however, that only subjects with
profound (near total or complete) deficiencies in MPO appear
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1108
Arterioscler Thromb Vasc Biol.
June 2005
HL077692, HL61878, and the General Clinical Research Center of
the Cleveland Clinic Foundation (RR018390). S.J.N. is supported by
a Ralph Reader Overseas Research Fellowship from the National
Heart Foundation of Australia.
References
Figure 4. Echocardiographic analysis of ventricle size in wildtype and MPO knockout mice after acute myocardial infarction.
Representative m-mode echocardiographic recordings from
wild-type (WT) and MPO knockout (MPO⫺/⫺) animals 21 days
after chronic ligation of the left anterior descending (LAD) artery.
Note that WT animals experience marked left ventricle (LV)
chamber dilatation and wall thinning after myocardial infarction
compared with the MPO⫺/⫺ mice. Functional studies demonstrate marked preservation in myocardial contractile capacity
(fractional shortening) as well in the MPO⫺/⫺ mice. LVEDD indicates left ventricular end-diastolic diameter. Reprinted with permission from Askari et al.38
to have a significant increase in risk for infections, and only
in the setting of concomitant factors that predispose to
immunosuppression, such as diabetes.112 Moreover, whereas
levels of MPO per leukocyte appear relatively stable in a
given subject over time, there appears to be a wide range of
MPO levels per leukocyte within populations of normal
subjects, and thus a large potential therapeutic range may
exist while maintaining MPO levels still within a functional
range for host defenses.31 Finally, MPO stores within leukocytes may be relatively protected from inhibition because the
enzyme is stored in a crystalline form within granules and
only released into the phagolysosome compartment and
extracellular space upon leukocyte activation.113 As a result,
through use of more polar inhibitors, it may be possible to
target extracellular MPO, such as enzyme trapped within the
subendothelial space, and not to significantly impede leukocyte killing of phagocytosed pathogens. The development of
MPO inhibitors awaits further investigation.
Summary
Generation of reactive oxidant species via MPO-catalyzed
pathways may have a substantial impact on the promotion of
inflammatory events that contribute not only to immune
defenses but also to the tissue damage that results from a
range of inflammatory conditions, including atherosclerosis.
MPO appears to participate in a range of events involved in
the initiation, propagation and subsequent complications of
atherosclerotic plaque. As a result, the components of the
MPO pathway represent attractive targets for the development of prognostic biomarkers and therapeutic interventions
to prevent atherosclerotic cardiovascular disease.
Acknowledgments
Research cited in this review was supported by National Institutes of
Health grants P01 HL076491, U01 HL077107, HL70621,
1. Ross R. Atherosclerosis–an inflammatory disease. N Engl J Med. 1999;
340:115–126.
2. Klebanoff SJ. Oxygen metabolism and the toxic properties of
phagocytes. Ann Intern Med. 1980;93:480 – 489.
3. Zhang R, Brennan ML, Shen Z, MacPherson JC, Schmitt D, Molenda
CE, Hazen SL. Myeloperoxidase functions as a major enzymatic catalyst
for initiation of lipid peroxidation at sites of inflammation. J Biol Chem.
2002;277:46116 – 46122.
4. Zhang R, Shen Z, Nauseef WM, Hazen SL. Defects in leukocytemediated initiation of lipid peroxidation in plasma as studied in
myeloperoxidase-deficient subjects: systematic identification of
multiple endogenous diffusible substrates for myeloperoxidase in
plasma. Blood. 2002;99:1802–1810.
5. Podrez EA, Abu-Soud HM, Hazen SL. Myeloperoxidase-generated
oxidants and atherosclerosis. Free Radic Biol Med. 2000;28:1717–1725.
6. Heinecke JW. Oxidative stress: new approaches to diagnosis and
prognosis in atherosclerosis. Am J Cardiol. 2003;91:12A–16A.
7. Rausch PG, Pryzwansky KB, Spitznagel JK. Immunocytochemical identification of azurophilic and specific granule markers in the giant
granules of Chediak-Higashi neutrophils. N Engl J Med. 1978;298:
693– 698.
8. Shultz J, Kaminker K. Myeloperoxidase of the leucocyte of normal
human blood. Arch Biochem Biophys. 1962;96:465– 467.
9. Bos A, Wever R, Roos D. Characterization and quantification of the
peroxidase in human monocytes. Biochim Biophys Acta. 1978;525:
37– 44.
10. Daugherty A, Dunn JL, Rateri DL, Heinecke JW. Myeloperoxidase, a
catalyst for lipoprotein oxidation, is expressed in human atherosclerotic
lesions. J Clin Invest. 1994;94:437– 444.
11. Nagra RM, Becher B, Tourtellotte WW, Antel JP, Gold D, Paladino T,
Smith RA, Nelson JR, Reynolds WF. Immunohistochemical and genetic
evidence of myeloperoxidase involvement in multiple sclerosis. J Neuroimmunol. 1997;78:97–107.
12. Sugiyama S, Okada Y, Sukhova GK, Virmani R, Heinecke JW, Libby P.
Macrophage myeloperoxidase regulation by granulocyte macrophage
colony-stimulating factor in human atherosclerosis and implications in
acute coronary syndromes. Am J Pathol. 2001;158:879 – 891.
13. Klebanoff SJ. Reactive nitrogen intermediates and antimicrobial
activity: role of nitrite. Free Radic Biol Med. 1993;14:351–360.
14. Cai H, Griendling KK, Harrison DG. The vascular NAD(P)H oxidases
as therapeutic targets in cardiovascular diseases. Trends Pharmacol Sci.
2003;24:471– 478.
15. Harrison D, Griendling KK, Landmesser U, Hornig B, Drexler H. Role
of oxidative stress in atherosclerosis. Am J Cardiol. 2003;91:7A–11A.
16. Weiss SJ, Test ST, Eckmann CM, Roos D, Regiani S. Brominating
oxidants generated by human eosinophils. Science. 1986;234:200 –203.
17. Klebanoff SJ. A peroxidase-mediated antimicrobial system in leukocytes. J Clin Invest. 1967;46:1078 –1085.
18. Klebanoff SJ. Myeloperoxidase: contribution to the microbicidal activity
of intact leukocytes. Science. 1970;169:1095–1097.
19. Malle E, Buch T, Grone HJ. Myeloperoxidase in kidney disease. Kidney
Int. 2003;64:1956 –1967.
20. Andreadis AA, Hazen SL, Comhair SA, Erzurum SC. Oxidative and
nitrosative events in asthma. Free Radic Biol Med. 2003;35:213–225.
21. Heinecke JW. Mechanisms of oxidative damage by myeloperoxidase in
atherosclerosis and other inflammatory disorders. J Lab Clin Med.
1999;133:321–325.
22. Hazen SL, Heinecke JW. 3-Chlorotyrosine, a specific marker of
myeloperoxidase-catalyzed oxidation, is markedly elevated in low
density lipoprotein isolated from human atherosclerotic intima. J Clin
Invest. 1997;99:2075–2081.
23. Thukkani AK, McHowat J, Hsu FF, Brennan ML, Hazen SL, Ford DA.
Identification of alpha-chloro fatty aldehydes and unsaturated lysophosphatidylcholine molecular species in human atherosclerotic lesions. Circulation. 2003;108:3128 –3133.
24. Beckman JS, Ye YZ, Anderson PG, Chen J, Accavitti MA, Tarpey MM,
White R. Extensive nitration of protein tyrosines in human atheroscle-
Downloaded from http://atvb.ahajournals.org/ by guest on February 21, 2013
Nicholls and Hazen
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
rosis detected by immunohistochemistry. Biol Chem Hoppe Seyler.
1993;375:81– 88.
Hazell LJ, Baernthaler G, Stocker R. Correlation between intimato-media ratio, apolipoprotein B-100, myeloperoxidase, and
hypochlorite-oxidized proteins in human atherosclerosis. Free Radic
Biol Med. 2001;31:1254 –1262.
Kutter D, Devaquet P, Vanderstocken G, Paulus JM, Marchal V, Gothot
A. Consequences of total and subtotal myeloperoxidase deficiency: risk
or benefit ? Acta Haematol. 2000;104:10 –15.
Nikpoor B, Turecki G, Fournier C, Theroux P, Rouleau GA. A functional myeloperoxidase polymorphic variant is associated with coronary
artery disease in French-Canadians. Am Heart J. 2001;142:336 –339.
Pecoits-Filho R, Stenvinkel P, Marchlewska A, Heimburger O, Barany
P, Hoff CM, Holmes CJ, Suliman M, Lindholm B, Schalling M,
Nordfors L. A functional variant of the myeloperoxidase gene is associated with cardiovascular disease in end-stage renal disease patients.
Kidney Int Suppl. 2003:S172–S176.
Asselbergs FW, Tervaert JW, Tio RA. Prognostic value of myeloperoxidase in patients with chest pain. N Engl J Med. 2004;350:516 –518;
author reply 516 –518.
Asselbergs FW, Reynolds WF, Cohen-Tervaert JW, Jessurun GA, Tio
RA. Myeloperoxidase polymorphism related to cardiovascular events in
coronary artery disease. Am J Med. 2004;116:429 – 430.
Zhang R, Brennan ML, Fu X, Aviles RJ, Pearce GL, Penn MS, Topol
EJ, Sprecher DL, Hazen SL. Association between myeloperoxidase
levels and risk of coronary artery disease. JAMA. 2001;286:2136 –2142.
Brennan ML, Penn MS, Van Lente F, Nambi V, Shishehbor MH, Aviles
RJ, Goormastic M, Pepoy ML, McErlean ES, Topol EJ, Nissen SE,
Hazen SL. Prognostic value of myeloperoxidase in patients with chest
pain. N Engl J Med. 2003;349:1595–1604.
Baldus S, Heeschen C, Meinertz T, Zeiher AM, Eiserich JP, Munzel T,
Simoons ML, Hamm CW. Myeloperoxidase serum levels predict risk in
patients with acute coronary syndromes. Circulation. 2003;108:
1440 –1445.
Brennan ML, Anderson MM, Shih DM, Qu XD, Wang X, Mehta AC,
Lim LL, Shi W, Hazen SL, Jacob JS, Crowley JR, Heinecke JW, Lusis
AJ. Increased atherosclerosis in myeloperoxidase-deficient mice. J Clin
Invest. 2001;107:419 – 430.
Nauseef WM. The proper study of mankind. J Clin Invest. 2001;107:
401– 403.
Brennan ML, Wu W, Fu X, Shen Z, Song W, Frost H, Vadseth C, Narine
L, Lenkiewicz E, Borchers MT, Lusis AJ, Lee JJ, Lee NA, Abu-Soud
HM, Ischiropoulos H, Hazen SL. A tale of two controversies: defining
both the role of peroxidases in nitrotyrosine formation in vivo using
eosinophil peroxidase and myeloperoxidase-deficient mice, and the
nature of peroxidase-generated reactive nitrogen species. J Biol Chem.
2002;277:17415–17427.
Eiserich JP, Baldus S, Brennan ML, Ma W, Zhang C, Tousson A, Castro
L, Lusis AJ, Nauseef WM, White CR, Freeman BA. Myeloperoxidase,
a leukocyte-derived vascular NO oxidase. Science. 2002;296:
2391–2394.
Askari AT, Brennan ML, Zhou X, Drinko J, Morehead A, Thomas JD,
Topol EJ, Hazen SL, Penn MS. Myeloperoxidase and plasminogen
activator inhibitor 1 play a central role in ventricular remodeling after
myocardial infarction. J Exp Med. 2003;197:615– 624.
Baldus S, Eiserich JP, Mani A, Castro L, Figueroa M, Chumley P, Ma
W, Tousson A, White CR, Bullard DC, Brennan ML, Lusis AJ, Moore
KP, Freeman BA. Endothelial transcytosis of myeloperoxidase confers
specificity to vascular ECM proteins as targets of tyrosine nitration.
J Clin Invest. 2001;108:1759 –1770.
Kannel WB, Castelli WP, Gordon T. Cholesterol in the prediction of
atherosclerotic disease. New perspectives based on the Framingham
study. Ann Intern Med. 1979;90:85–91.
MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled
trial. Lancet. 2002;360:7–22.
Randomised trial of cholesterol lowering in 4444 patients with coronary
heart disease: the Scandinavian Simvastatin Survival Study (4S). Lancet.
1994;344:1383–1389.
Shepherd J, Cobbe SM, Ford I, Isles CG, Lorimer AR, MacFarlane PW,
McKillop JH, Packard CJ. Prevention of coronary heart disease with
pravastatin in men with hypercholesterolemia. West of Scotland
Coronary Prevention Study Group. N Engl J Med. 1995;333:1301–1307.
Downs JR, Clearfield M, Weis S, Whitney E, Shapiro DR, Beere PA,
Langendorfer A, Stein EA, Kruyer W, Gotto AM, Jr. Primary prevention
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
Myeloperoxidase and Vascular Disease
1109
of acute coronary events with lovastatin in men and women with average
cholesterol levels: results of AFCAPS/TexCAPS. Air Force/Texas
Coronary Atherosclerosis Prevention Study. Jama. 1998;279:
1615–1622.
Sacks FM, Moye LA, Davis BR, Cole TG, Rouleau JL, Nash DT,
Pfeffer MA, Braunwald E. Relationship between plasma LDL concentrations during treatment with pravastatin and recurrent coronary events
in the Cholesterol and Recurrent Events trial. Circulation. 1998;97:
1446 –1452.
Brown MS, Dana SE, Goldstein JL. Regulation of 3-hydroxy-3methylglutaryl coenzyme A reductase activity in human fibroblasts by
lipoproteins. Proc Natl Acad Sci U S A. 1973;70:2162–2166.
Brown MS, Goldstein JL. Regulation of the activity of the low density
lipoprotein receptor in human fibroblasts. Cell. 1975;6:307–316.
Steinberg D, Parthasarathy S, Carew TE, Khoo JC, Witztum JL. Beyond
cholesterol. Modifications of low-density lipoprotein that increase its
atherogenicity. N Engl J Med. 1989;320:915–924.
O’Brien KD, Alpers CE, Hokanson JE, Wang S, Chait A. Oxidationspecific epitopes in human coronary atherosclerosis are not limited to
oxidized low-density lipoprotein. Circulation. 1996;94:1216 –1225.
Hessler JR, Morel DW, Lewis LJ, Chisolm GM. Lipoprotein oxidation
and lipoprotein-induced cytotoxicity. Arteriosclerosis. 1983;3:215–222.
Lehtimaki T, Lehtinen S, Solakivi T, Nikkila M, Jaakkola O, Jokela H,
Yla-Herttuala S, Luoma JS, Koivula T, Nikkari T. Autoantibodies
against oxidized low density lipoprotein in patients with angiographically verified coronary artery disease. Arterioscler Thromb Vasc
Biol. 1999;19:23–27.
Freigang S, Horkko S, Miller E, Witztum JL, Palinski W. Immunization
of LDL receptor-deficient mice with homologous malondialdehydemodified and native LDL reduces progression of atherosclerosis by
mechanisms other than induction of high titers of antibodies to oxidative
neoepitopes. Arterioscler Thromb Vasc Biol. 1998;18:1972–1982.
Leeuwenburgh C, Hardy MM, Hazen SL, Wagner P, Oh-ishi S, Steinbrecher
UP, Heinecke JW. Reactive nitrogen intermediates promote low density
lipoprotein oxidation in human atherosclerotic intima. J Biol Chem. 1997;272:
1433–1436.
Leeuwenburgh C, Rasmussen JE, Hsu FF, Mueller DM, Pennathur S,
Heinecke JW. Mass spectrometric quantification of markers for protein
oxidation by tyrosyl radical, copper, and hydroxyl radical in low density
lipoprotein isolated from human atherosclerotic plaques. J Biol Chem.
1997;272:3520 –3526.
Hazell LJ, Stocker R. Oxidation of low-density lipoprotein with hypochlorite causes transformation of the lipoprotein into a high-uptake form
for macrophages. Biochem J. 1993;290(Pt 1):165–172.
Hazell LJ, Arnold L, Flowers D, Waeg G, Malle E, Stocker R. Presence
of hypochlorite-modified proteins in human atherosclerotic lesions.
J Clin Invest. 1996;97:1535–1544.
Podrez EA, Schmitt D, Hoff HF, Hazen SL. Myeloperoxidase-generated
reactive nitrogen species convert LDL into an atherogenic form in vitro.
J Clin Invest. 1999;103:1547–1560.
Hazen SL, Zhang R, Shen Z, Wu W, Podrez EA, MacPherson JC,
Schmitt D, Mitra SN, Mukhopadhyay C, Chen Y, Cohen PA, Hoff HF,
Abu-Soud HM. Formation of nitric oxide-derived oxidants by myeloperoxidase in monocytes: pathways for monocyte-mediated protein
nitration and lipid peroxidation In vivo. Circ Res. 1999;85:950 –958.
Podrez EA, Febbraio M, Sheibani N, Schmitt D, Silverstein RL, Hajjar
DP, Cohen PA, Frazier WA, Hoff HF, Hazen SL. Macrophage
scavenger receptor CD36 is the major receptor for LDL modified by
monocyte-generated reactive nitrogen species. J Clin Invest. 2000;105:
1095–1108.
Febbraio M, Podrez EA, Smith JD, Hajjar DP, Hazen SL, Hoff HF,
Sharma K, Silverstein RL. Targeted disruption of the class B scavenger
receptor CD36 protects against atherosclerotic lesion development in
mice. J Clin Invest. 2000;105:1049 –1056.
Podrez EA, Poliakov E, Shen Z, Zhang R, Deng Y, Sun M, Finton PJ,
Shan L, Gugiu B, Fox PL, Hoff HF, Salomon RG, Hazen SL. Identification of a novel family of oxidized phospholipids that serve as ligands
for the macrophage scavenger receptor CD36. J Biol Chem. 2002;277:
38503–38516.
Podrez EA, Poliakov E, Shen Z, Zhang R, Deng Y, Sun M, Finton PJ,
Shan L, Febbraio M, Hajjar DP, Silverstein RL, Hoff HF, Salomon RG,
Hazen SL. A novel family of atherogenic oxidized phospholipids
promotes macrophage foam cell formation via the scavenger receptor
CD36 and is enriched in atherosclerotic lesions. J Biol Chem. 2002;277:
38517–38523.
Downloaded from http://atvb.ahajournals.org/ by guest on February 21, 2013
1110
Arterioscler Thromb Vasc Biol.
June 2005
63. Shishehbor MH, Aviles RJ, Brennan ML, Fu X, Goormastic M, Pearce
GL, Gokce N, Keaney JF, Jr., Penn MS, Sprecher DL, Vita JA, Hazen
SL. Association of nitrotyrosine levels with cardiovascular disease and
modulation by statin therapy. JAMA. 2003;289:1675–1680.
64. Bowry VW, Stanley KK, Stocker R. High density lipoprotein is the
major carrier of lipid hydroperoxides in human blood plasma from
fasting donors. Proc Natl Acad Sci U S A. 1992;89:10316 –10320.
65. Wang WQ, Merriam DL, Moses AS, Francis GA. Enhanced cholesterol
efflux by tyrosyl radical-oxidized high density lipoprotein is mediated
by apolipoprotein AI-AII heterodimers. J Biol Chem. 1998;273:
17391–17398.
66. Panzenbock U, Kritharides L, Raftery M, Rye KA, Stocker R. Oxidation
of methionine residues to methionine sulfoxides does not decrease
potential antiatherogenic properties of apolipoprotein A-I. J Biol Chem.
2000;275:19536 –19544.
67. Graham A, Vinogradov DV, Owen JS. Effects of peroxynitrite on
plasma components of the reverse cholesterol transport pathway. FEBS
Lett. 1998;431:327–332.
68. Panzenboeck U, Raitmayer S, Reicher H, Lindner H, Glatter O, Malle E,
Sattler W. Effects of reagent and enzymatically generated hypochlorite
on physicochemical and metabolic properties of high density
lipoproteins. J Biol Chem. 1997;272:29711–29720.
69. Nagano Y, Arai H, Kita T. High density lipoprotein loses its effect to
stimulate efflux of cholesterol from foam cells after oxidative modification. Proc Natl Acad Sci U S A. 1991;88:6457– 6461.
70. Bergt C, Marsche G, Panzenboeck U, Heinecke JW, Malle E, Sattler W.
Human neutrophils employ the myeloperoxidase/hydrogen peroxide/
chloride system to oxidatively damage apolipoprotein A-I. Eur
J Biochem. 2001;268:3523–3531.
71. Bergt C, Reicher H, Malle E, Sattler W. Hypochlorite modification of
high density lipoprotein: effects on cholesterol efflux from J774 macrophages. FEBS Lett. 1999;452:295–300.
72. Marsche G, Hammer A, Oskolkova O, Kozarsky KF, Sattler W, Malle
E. Hypochlorite-modified high density lipoprotein, a high affinity ligand
to scavenger receptor class B, type I, impairs high density lipoproteindependent selective lipid uptake and reverse cholesterol transport. J Biol
Chem. 2002;277:32172–32179.
73. Zheng L, Nukuna B, Brennan ML, Sun M, Goormastic M, Settle M,
Schmitt D, Fu X, Thomson L, Fox PL, Ischiropoulos H, Smith JD,
Kinter M, Hazen SL. Apolipoprotein A-I is a selective target for
myeloperoxidase-catalyzed oxidation and functional impairment in
subjects with cardiovascular disease. J Clin Invest. 2004;114:529 –541.
74. Zheng L, Settle M, Brubaker G, Schmitt D, Hazen SL, Smith JD, Kinter
M. Localization of nitration and chlorination sites on apolipoprotein A-I
catalyzed by myeloperoxidase in human atheroma and associated oxidative impairment in ABCA1-dependent cholesterol efflux from macrophages. J Biol Chem. 2005;280:38 – 47.
75. Bergt C, Pennathur S, Fu X, Byun J, O’Brien K, McDonald TO, Singh
P, Anantharamaiah GM, Chait A, Brunzell J, Geary RL, Oram JF,
Heinecke JW. The myeloperoxidase product hypochlorous acid oxidizes
HDL in the human artery wall and impairs ABCA1-dependent cholesterol transport. Proc Natl Acad Sci U S A. 2004;101:13032–13037.
76. Pennathur S, Bergt C, Shao B, Byun J, Kassim SY, Singh P, McDonald
TO, Brunzell J, Chait A, Oram JF, O’Brien K, Geary RL, Heinecke JW.
Human atherosclerotic intima and blood of patients with established
coronary artery disease contain high density lipoprotein damaged by
reactive nitrogen species. J Biol Chem. 2004;279:42977– 42983.
77. Malle E, Wag G, Thiery J, Sattler W, Grone HJ. Hypochlorite-modified
(lipo)proteins are present in rabbit lesions in response to dietary cholesterol. Biochem Biophys Res Commun. 2001;289:894 –900.
78. Harrison DG. Cellular and molecular mechanisms of endothelial cell
dysfunction. J Clin Invest. 1997;100:2153–2157.
79. Forgione MA, Leopold JA, Loscalzo J. Roles of endothelial dysfunction
in coronary artery disease. Curr Opin Cardiol. 2000;15:409 – 415.
80. Celermajer DS, Sorensen KE, Bull C, Robinson J, Deanfield JE. Endothelium-dependent dilation in the systemic arteries of asymptomatic
subjects relates to coronary risk factors and their interaction. J Am Coll
Cardiol. 1994;24:1468 –1474.
81. Ludmer PL, Selwyn AP, Shook TL, Wayne RR, Mudge GH, Alexander
RW, Ganz P. Paradoxical vasoconstriction induced by acetylcholine in
atherosclerotic coronary arteries. N Engl J Med. 1986;315:1046 –1051.
82. Egashira K, Hirooka Y, Kai H, Sugimachi M, Suzuki S, Inou T,
Takeshita A. Reduction in serum cholesterol with pravastatin improves
endothelium-dependent coronary vasomotion in patients with hypercholesterolemia. Circulation. 1994;89:2519 –2524.
83. Curtis JF, Reddy NG, Mason RP, Kalyanaraman B, Eling TE. Nitric
oxide: a prostaglandin H synthase 1 and 2 reducing cosubstrate that does
not stimulate cyclooxygenase activity or prostaglandin H synthase
expression in murine macrophages. Arch Biochem Biophys. 1996;335:
369 –376.
84. Abu-Soud HM, Hazen SL. Nitric oxide is a physiological substrate for
mammalian peroxidases. J Biol Chem. 2000;275:37524 –37532.
85. Zhang C, Reiter C, Eiserich JP, Boersma B, Parks DA, Beckman JS,
Barnes S, Kirk M, Baldus S, Darley-Usmar VM, White CR. L-arginine
chlorination products inhibit endothelial nitric oxide production. J Biol
Chem. 2001;276:27159 –27165.
86. Zhang C, Patel R, Eiserich JP, Zhou F, Kelpke S, Ma W, Parks DA,
Darley-Usmar V, White CR. Endothelial dysfunction is induced by
proinflammatory oxidant hypochlorous acid. Am J Physiol Heart Circ
Physiol. 2001;281:H1469 –H1475.
87. Zou MH, Shi C, Cohen RA. Oxidation of the zinc-thiolate complex and
uncoupling of endothelial nitric oxide synthase by peroxynitrite. J Clin
Invest. 2002;109:817– 826.
88. Marsche G, Heller R, Fauler G, Kovacevic A, Nuszkowski A, Graier W,
Sattler W, Malle E. 2-Chlorohexadecanal derived from hypochloritemodified high-density lipoprotein-associated plasmalogen is a natural
inhibitor of endothelial nitric oxide biosynthesis. Arterioscler Thromb
Vasc Biol. 2004;24:2302–2306.
89. Auchere F, Capeillere-Blandin C. NADPH as a co-substrate for studies
of the chlorinating activity of myeloperoxidase. Biochem J. 1999;343(Pt
3):603– 613.
90. Abu-Soud HM, Khassawneh MY, Sohn JT, Murray P, Haxhiu MA,
Hazen SL. Peroxidases inhibit nitric oxide (NO) dependent bronchodilation: development of a model describing NO-peroxidase interactions.
Biochemistry. 2001;40:11866 –11875.
91. Baldus S, Eiserich JP, Brennan ML, Jackson RM, Alexander CB,
Freeman BA. Spatial mapping of pulmonary and vascular nitrotyrosine
reveals the pivotal role of myeloperoxidase as a catalyst for tyrosine
nitration in inflammatory diseases. Free Radic Biol Med. 2002;33:1010.
92. Vita JA, Brennan ML, Gokce N, Mann SA, Goormastic M, Shishehbor
MH, Penn MS, Keaney JF, Jr., Hazen SL. Serum myeloperoxidase
levels independently predict endothelial dysfunction in humans. Circulation. 2004;110:1134 –1139.
93. Baldus S, Heitzer T, Eiserich JP, Lau D, Mollnau H, Ortak M, Petri S,
Goldmann B, Duchstein HJ, Berger J, Helmchen U, Freeman BA,
Meinertz T, Munzel T. Myeloperoxidase enhances nitric oxide
catabolism during myocardial ischemia and reperfusion. Free Radic Biol
Med. 2004;37:902–911.
94. Falk E, Shah PK, Fuster V. Coronary plaque disruption. Circulation.
1995;92:657– 671.
95. Aikawa M, Libby P. Lipid lowering reduces proteolytic and prothrombotic potential in rabbit atheroma. Ann N Y Acad Sci. 2000;902:
140 –152.
96. Davies MJ. Going from immutable to mutable atherosclerotic plaques.
Am J Cardiol. 2001;88:2F–9F.
97. Naruko T, Ueda M, Haze K, van der Wal AC, van der Loos CM, Itoh
A, Komatsu R, Ikura Y, Ogami M, Shimada Y, Ehara S, Yoshiyama M,
Takeuchi K, Yoshikawa J, Becker AE. Neutrophil infiltration of culprit
lesions in acute coronary syndromes. Circulation. 2002;106:2894 –2900.
98. de Servi S, Mazzone A, Ricevuti G, Mazzucchelli I, Fossati G, Angoli
L, Valentini P, Boschetti E, Specchia G. Expression of neutrophil and
monocyte CD11B/CD18 adhesion molecules at different sites of the
coronary tree in unstable angina pectoris. Am J Cardiol. 1996;78:
564 –568.
99. Buffon A, Biasucci LM, Liuzzo G, D’Onofrio G, Crea F, Maseri A.
Widespread coronary inflammation in unstable angina. N Engl J Med.
2002;347:5–12.
100. Fu X, Kassim SY, Parks WC, Heinecke JW. Hypochlorous acid oxygenates the cysteine switch domain of pro-matrilysin (MMP-7). A
mechanism for matrix metalloproteinase activation and atherosclerotic
plaque rupture by myeloperoxidase. J Biol Chem. 2001;276:
41279 – 41287.
101. Peppin GJ, Weiss SJ. Activation of the endogenous metalloproteinase,
gelatinase, by triggered human neutrophils. Proc Natl Acad Sci U S A.
1986;83:4322– 4326.
102. Fu X, Kassim SY, Parks WC, Heinecke JW. Hypochlorous acid generated by myeloperoxidase modifies adjacent tryptophan and glycine
residues in the catalytic domain of matrix metalloproteinase-7 (matrilysin): an oxidative mechanism for restraining proteolytic activity during
inflammation. J Biol Chem. 2003;278:28403–28409.
Downloaded from http://atvb.ahajournals.org/ by guest on February 21, 2013
Nicholls and Hazen
103. Sugiyama S, Kugiyama K, Aikawa M, Nakamura S, Ogawa H, Libby P.
Hypochlorous acid, a macrophage product, induces endothelial apoptosis and tissue factor expression: involvement of myeloperoxidasemediated oxidant in plaque erosion and thrombogenesis. Arterioscler
Thromb Vasc Biol. 2004;24:1309 –1314.
104. Farb A, Burke AP, Tang AL, Liang TY, Mannan P, Smialek J, Virmani
R. Coronary plaque erosion without rupture into a lipid core. A frequent
cause of coronary thrombosis in sudden coronary death. Circulation.
1996;93:1354 –1363.
105. Hazen SL. Myeloperoxidase and plaque vulnerability. Arterioscler
Thromb Vasc Biol. 2004;24:1143–1146.
106. Arbustini E, Dal Bello B, Morbini P, Burke AP, Bocciarelli M, Specchia
G, Virmani R. Plaque erosion is a major substrate for coronary
thrombosis in acute myocardial infarction. Heart. 1999;82:269 –272.
107. Bombeli T, Schwartz BR, Harlan JM. Endothelial cells undergoing
apoptosis become proadhesive for nonactivated platelets. Blood. 1999;
93:3831–3838.
Myeloperoxidase and Vascular Disease
1111
108. Landmesser U, Hornig B, Drexler H. Endothelial function: a critical
determinant in atherosclerosis? Circulation. 2004;109:II27–II33.
109. Penn MS, Patel CV, Cui MZ, DiCorleto PE, Chisolm GM. LDL
increases inactive tissue factor on vascular smooth muscle cell surfaces:
hydrogen peroxide activates latent cell surface tissue factor. Circulation.
1999;99:1753–1759.
110. Penn MS, Cui MZ, Winokur AL, Bethea J, Hamilton TA, DiCorleto PE,
Chisolm GM. Smooth muscle cell surface tissue factor pathway activation by oxidized low-density lipoprotein requires cellular lipid peroxidation. Blood. 2000;96:3056 –3063.
111. Seekamp A, Ward PA. Ischemia-reperfusion injury. Agents Actions
Suppl. 1993;41:137–152.
112. Nauseef WM. Insights into myeloperoxidase biosynthesis from its
inherited deficiency. J Mol Med. 1998;76:661– 668.
113. Nauseef WM. Contributions of myeloperoxidase to proinflammatory
events: more than an antimicrobial system. Int J Hematol. 2001;74:
125–133.
Downloaded from http://atvb.ahajournals.org/ by guest on February 21, 2013