Review and Hypothesis:
Vulnerable Plaque Formation from Obstruction of Vasa Vasorum
by Homocysteinylated and Oxidized Lipoprotein Aggregates
Complexed with Microbial Remnants and LDL Autoantibodies
and Kilmer S. McCully
Independent Investigator, Magle Stora Kyrkogata 9, 22350 Lund, Sweden;
Pathology and Laboratory
Medicine Service, Boston Veterans Aﬀairs Healthcare System, West Roxbury, MA;
Pathology, Harvard Medical School, Boston MA, USA.
Abstract. Little attention has been paid to the function of lipoproteins as part of a nonspeciﬁc immune
defense system that binds and inactivates microbes and their toxins eﬀectively by complex formation.
Because of high extra-capillary tissue pressure, aggregates of such complexes may be trapped in vasa vasorum
of the major arteries. is complex formation and aggregation may be enhanced by hyperhomocysteinemia,
because homocysteine thiolactone reacts with the free amino groups of apo-B to form homocysteinylated
low-density lipoprotein (LDL), which is subject to spontaneous precipitation in vitro. Obstruction of the
circulation in vasa vasorum, caused by the aggregated complexes, may result in local ischemia in the arterial
wall, intramural cell death, bursting of the capillary, and escape of microorganisms into the intima, all of
which lead to inﬂammation and creation of vulnerable plaques. e presence of homocysteinylated LDL
and oxidized LDL stimulates production of LDL autoantibodies, which may start a vicious circle by
increasing the complex formation and aggregation of lipoproteins. e content of necrotic debris and
leukocytes and the higher temperature than its surroundings give the vulnerable plaque some characteristics
of a micro-abscess that by rupturing may initiate an occluding thrombosis. is suggested chain of events
explains why many of the clinical symptoms and laboratory ﬁndings in acute myocardial infarction are
similar to those seen in infectious diseases. It explains the presence of microorganisms in atherosclerotic
plaques and why bacteriemia and sepsis are often seen in myocardial infarction complicated with cardiogenic
shock. It explains the many associations between infections and cardiovascular disease. And it explains
why cholesterol accumulates in the arterial wall. Some risk factors may not cause vascular disease directly,
but they may impair the immune system, promote microbial growth, or cause hyperhomocysteinemia,
leading to vulnerable plaques.
Keywords: vulnerable plaque, lipoprotein aggregates, vasa vasorum, hyperhomocysteinemia, microbial
remnants, autoimmunity, oxidized LDL
Introduction. ere is general agreement that
atherosclerosis begins as an inﬂammatory process
in the arterial wall, and also that rupture of a
vulnerable plaque is the starting point for the
creation of the occluding thrombus in myocardial
infarction and ischemic stroke [1,2]. erefore, any
hypothesis about the cause of atherosclerosis and its
consequences must necessarily be able to point to
the origin of the inﬂammation and to explain how
a vulnerable plaque is created .
According to the current view, the ﬁrst step is
endothelial dysfunction or damage caused by
hypercholesterolemia, hyperhomocysteinemia, or
other toxic factors in the circulation, allowing the
migration of LDL, cholesterol, and monocytes into
the arterial wall. LDL is modiﬁed by oxidation,
Address correspondence to Kilmer S. McCully, M.D.,
Veterans Aﬀairs Medical Center, West Roxbury, MA 02132,
USA; tel 857 203 5990; fax 857 203 5623; email kilmer.
0091-7370/09/0100-0003. $4.80. © 2009 by the Association of Clinical Scientists, Inc.
Available online at www.annclinlabsci.org
Annals of Clinical & Laboratory Science, vol. 39, no. 1, 2009
leading to an accumulation of T-cells and the
production of LDL autoantibodies. Modiﬁed LDL
is taken up by macrophages that are converted to
lipid-laden foam cells, considered as the early lesion
of atherosclerosis. e inﬂammatory process,
probably aggravated by antigens from microbes
such as Chlamydia, Herpes simplex and Cytomegalo-
virus, is followed by smooth muscle cell proliferation
and the synthesis of extracellular matrix. e
macrophages may become overloaded with lipids
and die, resulting in the creation of a vulnerable
plaque that by rupturing initiates the formation of
an occluding thrombus .
is suggested chain of events is based mainly
on epidemiological observations and experimental
models, where vascular changes similar to human
atherosclerosis have been produced in rodents with
inherited or dietary hypercholesterolemia. How-
ever, it conﬂicts with many clinical, epidemio-
logical, pathological, and experimental observations.
ere are in particular six disturbing facts:
1. e concept that high LDL cholesterol causes
endothelial dysfunction is unlikely because there is
no association between the concentration of LDL
cholesterol in the blood and the degree of endothelial
2. e concept that endothelial damage leads to
inﬂux of LDL cholesterol is unlikely as well, because
the atherosclerotic plaques seen in extreme hyper-
homocysteinemia caused by inborn errors of
methionine metabolism do not contain any lipids
in spite of pronounced endothelial damage [6,7].
3. No study of unselected individuals has found
an association between the concentration of LDL
or total cholesterol in the blood and the degree of
atherosclerosis at autopsy .
4. In studies of women and the elderly, hyperchol-
esterolemia is a weak risk factor for cardiovascular
disease, or, in most cases, not a risk factor at all ,
although the large majority of cardiovascular deaths
occur in people above 65 years of age.
5. Among individuals with familial hyperchol-
esterolemia (FH) there is no association between
LDL-cholesterol and the prevalence or the progress
of cardiovascular disease [10-15]. e higher
coronary mortality in young people with FH may
instead be due to inherited abnormalities of the
coagulation system, often seen in FH and a strong
risk factor for coronary heart disease in this
6. With one exception , an occluding coronary
thrombus has never been produced experimentally
in rodents by hypercholesterolemia alone ,
indicating that the pathological process in these
models may diﬀer from that in human beings.
Origin of vulnerable plaques. In the following
discussion we present a new interpretation of the
origin of vulnerable plaques that we think is in
better agreement with presently available evidence.
is interpretation is based on the fact that the
lipoproteins function as a nonspeciﬁc immune
system that binds and inactivates microorganisms
and their toxins by complex formation. In the case
of a massive microbial invasion, these complexes
may aggregate, in particular in the presence of
hyperhomocysteinemia, because homocysteine
thiolactone causes aggregation and precipitation of
thiolated LDL . Complex formation and
aggregation may also be enhanced by autoantibodies
against thiolated LDL and oxidized LDL. Because
of high extra-capillary tissue pressure, the aggregates
may be trapped in arterial vasa vasorum, resulting
in local vascular ischemia, intramural cell death,
and the creation of vulnerable plaques.
Such plaques have many characteristics of a
micro-abscess, which, by rupturing, initiates the
occluding thrombosis and releases its content of
infectious material into the circulation and the
myocardium. is suggested chain of events
explains why many of the clinical symptoms and
laboratory ﬁndings in acute myocardial infarction
are similar to those seen in infectious diseases. It
also explains the frequent presence of microbial
remnants in atherosclerotic plaques, the many
associations between infections and cardiovascular
disease, the similarities between myocarditis and
myocardial infarction, and why cholesterol
accumulates in the arterial wall.
e microbial hypothesis. A century ago, bacteria
and viruses were considered as the main cause of
atherosclerosis, a view that was based mainly on
post-mortem observations. us, ayer reported
a high frequency of arterial lesions in patients who
died from typhoid fever and a high prevalence of
Annals of Clinical & Laboratory Science, vol. 39, no. 1, 2009
hardened radial arteries in those who survived .
Wiesel found an association between the degree of
atherosclerosis in people who had died from an
infectious disease and the length of the preceding
infection , and Osler described the vulnerable
plaque as an atherosclerotic pustule . e
following statement by Klotz and Manning is
typical for the general view at that time: “ere is
every indication that the production of tissue in the
intima is the result of a direct irritation of that
tissue by the presence of infection or toxins” .
e molecular mechanisms were unknown and
because of the chemical composition of advanced
atherosclerotic plaques, more recent research has
instead focused on cholesterol.
However, in addition to and in accordance
with the older ﬁndings, much epidemiological,
clinical, laboratory, and experimental evidence has
more recently been reported, suggesting that
infectious processes may play a role in cardiovascular
disease [23-27]. Cardiovascular mortality increases
during inﬂuenza epidemics . A third of patients
with acute myocardial infarction or stroke have
had an infectious disease immediately before onset
. Bacteriemia and periodontal infections are
associated with an increased risk of cardiovascular
disease [30,31]. Serological markers of infection
are often elevated in patients with cardiovascular
disease and are also risk factors for such diseases
. A role of infectious agents is suggested by the
narrowing of the coronary arteries seen in children
who died from an infectious disease  and from
thickening of carotid intima-media on high-
resolution ultrasound in those who survived .
e lipoprotein immune system. A normal serum
factor is able to neutralize the hemolytic eﬀects of
streptolysin-S, and, for this reason, the factor was
named antistreptolysin-S and was previously
considered to be an antibody. However, this
concept was questioned in 1939 by Todd et al, who
found that this serum factor did not behave as a
normal antibody because its titer fell below normal
values in patients with rheumatic fever at the peak
of the clinical symptoms . A few years later,
Stollerman and Bernheimer also found that, in
contrast to the antistreptococcal antibodies, the
antistreptolysin-S titer did not rise above its normal
level during convalescence . At the same time,
Humphrey discovered that antistreptolysin-S was
located within the lipid fraction of the blood .
Stollerman et al identiﬁed antistreptolysin-S as a
phospholipoprotein complex . Since then, at
least a dozen research groups have established that
antistreptolysin-S is identical with the lipoproteins
and constitutes a nonspeciﬁc host defense system,
able to bind and inactivate not only streptolysin-S,
but also other endotoxins and several virus species
[39-55] (Table 1). In rodents, cholesterol is mostly
transported by high-density lipoprotein (HDL),
and in these species HDL has the main protective
eﬀect [42,43], whereas human studies have
generally found that all lipoproteins participate in
the nonspeciﬁc defense system.
Most investigators have identiﬁed the
immunoprotective role of the lipoproteins by
demonstrating inhibition of the biological eﬀects
of various microorganisms and endotoxins, such as
hemagglutination, hemolysis, the cytokine response
of human monocytes, and virus replication.
Skarnes ﬁrst suggested that the lipoproteins also
form complexes with microbial products . By
using immunodiﬀusion with anti-endotoxin and
serum from various rodents that had been injected
with Salmonella enteridis endotoxin, he demon-
strated lipoprotein-positive staining and esterase
activity on the precipitation lines.
Using crossed immunoelectrophoresis, Freud-
enberg et al found that the HDL peak of rat plasma
changed position after injection with various
lipopolysaccharides (LPS); they concluded that the
eﬀect was due to the formation of a complex
between LPS and HDL . By separating a
mixture of rabbit plasma and LPS from Salmonella
minnesota by column chromatography with
sepharose linked with LPS antibody, Ulevitch et al
found that the eluate from the bound material
contained both LPS and apoprotein A1, the major
protein of rabbit HDL . ere is strong evidence
that human lipoproteins complex with microbial
components as well. By electron microscopy (EM)
Bhakdi et al found that the inactivation of
Staphylococcus aureus alpha-toxin by puriﬁed
human LDL led to oligomerization of 3S native
toxin molecules into ring structures of 11S hexamers
that adhered to the LDL molecules .
Vulnerable plaques from lipoprotein aggregates
Lipoproteins also form complexes with viruses.
Huemer et al found that all lipoprotein subclasses
were able to bind puriﬁed Herpes simplex virus, as
demonstrated by EM, enzyme-linked immuno-
absorbence assay, and column chromatography
. Superti et al conﬁrmed that all human
subclasses of lipoproteins were able to inhibit the
infectivity and hemagglutination by SA-11 rota-
virus, and complex formation was visualized by
e lipoprotein immune system may be
particularly important in early childhood as, in
contrast to antibody-producing cells, this system
works immediately and with high eﬃciency. For
instance, human LDL inactivated up to 90% of
Staphylococcus aureus alpha-toxin , and it
inactivated an even larger fraction of bacterial
lipopolysaccharide (LPS) . In agreement with
these ﬁndings, hypocholesterolemic rats injected
with LPS had a markedly increased mortality
compared with normal rats, which could be
ameliorated by injecting puriﬁed human LDL .
On the other hand, hypercholesterolemic mice
challenged with LPS or live bacteria had an
eightfold increase of LD
, compared with normal
Hudgins et al demonstrated that high-
molecular weight lipoproteins not only bind LPS,
but lipoproteins disappear from the general
circulation in infected human beings . ey
injected a small dose of LPS in normal volunteers
and demonstrated the expected rise of the usual
inﬂammatory markers and a fall of total cholesterol,
LDL-cholesterol and apo-B, whereas concentrations
of HDL-cholesterol and apo-A1 were unchanged.
e formation of complexes between
lipoproteins and microbial products may lead to
aggregation of lipoprotein particles. In case of a
Table 1. Binding of microbial products by lipoproteins.
Ref. Microbial product LDL HDL VLDL All Source Methods used to demonstrate inactivation
lipoproteins of lipo- and/or binding of the microbial products
proteins by the lipoproteins
37 Streptolysin S ++ human Inhibition of streptolysin S
38 Streptolysin S ++ ++ human Inhibition of streptolysin S
39 LPS; S. enteritides ++ rodents Immunodiﬀusion
40 Togavirus ++ + +++ human Inhibition of hemagglutination
41 S. aureus δ-hemolysin ++ ++ human Inhibition of δ-hemolysin
42 S. abortus equi; ++ rat Crossed
S. minnesota 0 ++ 0 rat immunoelectrophoresis
43 LPS; S. minnesota 0 ++ 0 rabbit Binding of LPS to apoA1
44 S. aureus a-toxin ++ 0 human Hemolytic titration; EM
45 Rhabdovirus ++ (+) ++ human Inhibition of hemagglutination
46 LPS; E. coli ++ ++ ++ human, rabbit Inhibition of scavenger receptor
47 Herpes simplex ++ ++ ++ human EM
48 LPS; E. coli ++ human Inhibition of endotoxin activation of
49 LPS; E. coli ++ + ++ rabbit Inhibition of cytokine-response of
50 LPS (?) ++ ++ 0 human Inhibition of cytokine-response of
51 SA Rotavirus ++ ++ ++ human Inhibition of viral hemagglutination
and replication; EM
52 LPS; S. typhi ++ human Inhibition of endotoxin production
53 LPS; S. typhi ++ (+) 0 human Inhibition of endotoxin production
54 LPS; E. coli ++ human Endotoxin sensitivity
55 LPS; E. coli ++ mouse LD
after experimental infection
A semiquantitative review presents the binding and inhibitory eﬀects of low-density (LDL), high-density (HDL), and very low-
density (VLDL) lipoprotein on various microbes and bacterial toxins. In 5 studies the total eﬀects of all lipoproteins together
were examined. Abbreviations: electron microscopy (EM); lethal dose 50% (LD
); lipopolysaccharide (LPS); apolipoprotein
A1 of high-density lipoprotein (ApoA1).
Annals of Clinical & Laboratory Science, vol. 39, no. 1, 2009
massive invasion of microorganisms, the size of
such aggregates, especially those composed of the
high-molecular weight VLDL and LDL, may
impede their passage through capillary networks,
in particular the vasa vasorum of the artery walls,
because of high extra-capillary tissue pressure.
Indeed, aggregated lipid structures similar to the
size of LDL have been demonstrated by electron
microscopy in the extracellular space beneath fatty
Recent reviews [58,59] summarized the evidence
that both LPS and lipoteichoic acid (the Gram-
positive counterpart of LPS) form aggregates in
solution. In addition, sphingolipids interact with
bacterial toxins, and all lipoproteins isolated from
animals treated with LPS contain high levels of
sphingolipids (ceramide), which promote lipo-
An unsettled question concerns the nature of
the process that converts macrophages into lipid-
laden foam cells, one of the main factors in
production of atherosclerotic lesions. Normally
excess cellular uptake of cholesterol is counteracted
by down-regulation of the LDL receptor, indicating
that another pathway must be responsible for foam
cell formation. According to the current view,
oxidized LDL cholesterol in the arterial wall is
taken up by the scavenger receptor of macrophages,
allowing an unlimited uptake of cholesterol,
independent of the LDL receptor. However, macro-
phages also take up aggregated LDL by phagocytosis
after modiﬁcation by vortexing or by digestion
with phospholipase C . LDL that is modiﬁed
by complex binding with microbial products is also
taken up by the same process, because in vitro
experiments have shown that LPS from Chlamydia
pneumoniae  and also from several periodontal
pathogens  is able to convert macrophages to
foam cells in the presence of human LDL.
A direct attack of microorganisms or their
products on the endothelium, as often suggested,
seems unlikely, as demonstrated by Madjid et al
. In a post-mortem study of 27 patients with
coronary atherosclerosis, 14 of whom had had a
systemic infection within two weeks before death,
luminal coronary thromboses and myocardial
infarction were found in 5 of the infected patients.
ey found that the number of macrophages in the
infected group was much greater in the adventitia
than around the plaques, whereas no diﬀerence was
noted in the uninfected control group, which
suggests that the microbes arrive via vasa vasorum.
In agreement with this view, Guyton et al found
that extracellular lipid deposits are almost entirely
located deep within the intima, close to the vasa
vasorum and well below most of the foam cell lipid
. is ﬁnding opposes the view that the lipid-
rich core region of plaques originates primarily
from the debris of dead intimal foam cells, but the
ﬁnding agrees with the spontaneous athero-
thrombosis observed in genetic double knockout
mice . ese thrombi were demonstrated on
the surface of atherosclerotic lesions similar to
human vulnerable plaques, accompanied by marked
medial degeneration and invasion of inﬂammatory
cells into the adventitia.
During the oxidative breakdown of microbial
material inside macrophages, cholesterol is partially
oxidized and returned to the liver by HDL, and the
cholesterol content of ﬁbrous plaques is not higher
than in normal arterial tissue . Indeed, several
HDL processes that are able to convert oxidized
LDL cholesterol to free cholesterol have been
identiﬁed . Also, esteriﬁed cholesterol may be
converted to free cholesterol by microbial processes
 and deposited as extracellular cholesterol
crystals found deep within the intima .
Hyperhomocysteinemia and autoimmunity.
Homocysteine thiolactone, the reactive cyclic
anhydride of homocysteine, reacts with free amino
groups of protein to form peptide-bound
homocysteine . e process of homocysteinyl-
ation of proteins is termed thiolation, because this
reaction produces a free sulfhydryl group within
the peptide-bound homocysteine molecule. Homo-
cysteine thiolactone reacts with the free amino
groups of apoB protein of LDL . When an
increased concentration of homocysteine
thiolactone reacts with human LDL, the thiolated
LDL becomes aggregated and subject to spontaneous
precipitation . LDL aggregates are phagocytosed
by cultured human macrophages, forming foam
cells with greatly increased cholesterol and
cholesterol ester content.
Vulnerable plaques from lipoprotein aggregates
It was suggested  that thiolation of LDL
would also alter its antigenic properties and lead to
autoantibody formation. Ferguson et al showed
that thiolated LDL is immunogenic in rabbits,
producing a polyclonal antibody recognizing
thiolated LDL . Antibodies to N-thiolated
serum albumin were demonstrated in patients with
coronary heart disease [71,72]. iolated LDL is
present in human serum at low concentration
(0.04-0.1%), but autoantibodies to human thiolated
LDL have not been reported .
e possibility that autoantibodies against
thiolated LDL may play a role in the creation of
atherosclerosis is suggested by other observations.
Hyperhomocysteinemia, a potent risk factor for
atherosclerosis, is found in autoimmune diseases,
such as lupus erythematosus, rheumatoid arthritis,
Behcet’s disease, inﬂammatory bowel disease, and
myelodysplastic syndrome . ese diseases all
are characterized by increased susceptibility to
vascular disease and activation of immunity and
inﬂammation. Homocysteine activates cytokines
and pro-inﬂammatory molecules, such as IL-1beta,
IL-6, IL-12, IL-18, IL-1 receptor antagonist, C-
reactive protein (CRP), adhesion molecules (P-
selectin, E-selectin, ICAM-1), and metallo-
proteinases (MMP-9). Homocysteine up-regulates
reactive oxygen species, leading to NF-kappaB
activation . CRP binds oxidized LDL and
oxidized phospholipids, enhancing phagocytosis to
form foam cells .
Oxidized LDL and autoimmunity. Oxidized LDL
(OxLDL) has long been considered as the main
culprit in atherosclerosis. OxLDL stimulates the
production of autoantibodies, but the role of anti-
OxLDL has been controversial because its titer
does not reﬂect or predict cardiovascular disease
[76-80]. We envision that anti-OxLDL antibodies
may aggregate and participate in the obstruction of
vasa vasorum. erefore, the reason the titer of
anti-OxLDL does not reﬂect cardiovascular disease
may be that the expected increased level of anti-
OxLDL in patients with cardiovascular disease is
counteracted by a decrease in anti-OxLDL level
because of the accumulation and aggregation of
circulating anti-OxLDL within vasa vasorum of
arteries. In support of this concept, Schumacher et
al found that patients with acute myocardial
infarction and a marked elevation of plasma
creatine kinase had a signiﬁcant decrease of anti-
OxLDL during the acute phase, whereas this
phenomenon was not seen in patients with only a
minor elevation of creatine kinase . Su et al
found an inverse association between the
concentration of anti-OxLDL and progress of
atherosclerosis in hypertensive patients, measured
as change of the maximum carotid intima-media
thickness, suggesting that anti-OxLDL is protective
against atherogenesis . is interpretation may
be correct in healthy, non-infected people without
hyperhomocysteinemia. However, the association
may also be explained by the disappearance from
the circulation of anti-OxLDL immune complexes
by their aggregation with LDL within vasa vasorum,
because the association was signiﬁcant for IgM
subclasses only, and the much larger size of such
complexes may render them more susceptible to
aggregation. is interpretation may also explain
the recent ﬁnding that low levels of IgM antibodies
against phosphorylcholine, a component of inﬂam-
matory phospholipids known to cause OxLDL-
related immune reactions, are associated with a
greater risk of ischemic stroke .
Creation of the vulnerable plaque. Obstruction of
the vasa vasorum by aggregated lipoprotein
complexes may increase the vulnerability of the
cells that they nourish and lead to cell death because
of localized ischemia of the vascular wall. Vasa
vasorum may rupture, and the aggregated LDL
particles with their load of microbial products will
enter the arterial wall. ese products may include
living microorganisms, because viable Chlamydia
pneumoniae have been cultured from atherosclerotic
plaques by Ramirez  and Jackson et al .
Probably this is a common phenomenon, because
Maass et al identiﬁed viable Chlamydia pneumoniae
in 11 of 70 atheromas, whereas none was present in
17 non-atherosclerotic control samples . e
presence of Chlamydia pneumoniae in human
coronary plaques was conﬁrmed by electron
microscopy [87,88]. ese organisms were also
demonstrated within adventitia by immunohisto-
chemical staining and polymerase chain reaction
(PCR) for microbial DNA, presumably arriving via
Annals of Clinical & Laboratory Science, vol. 39, no. 1, 2009
monocytes migrating from vasa vasorum .
Other living microorganisms may be present as
well, but to our knowledge no successful isolations
from human plaques have been reported.
Indirect evidence of a role of living micro-
organisms in the creation of vulnerable plaques was
presented by Grattan et al . ey found graft
failure because of accelerated atherosclerosis in
two-thirds of 91 cardiac transplant patients infected
with Cytomegalovirus, but only in one-third of 209
With a healthy immune system, the micro-
organisms may be eliminated, new capillaries will
enter the lesion, and reparative processes will
convert the dead tissue into a stable, ﬁbrous plaque.
But in case of an insuﬃcient clearing of the
Fig. 1. Development of the vulnerable plaque. e small globules inside the vasa vasorum and in the vulnerable plaque represent
lipoproteins; the black dots represent microorganisms, endotoxins, anti-OxLDL autoantibodies, and anti-thiolated-LDL
autoantibodies; the large globules at the basal part of the vulnerable plaque and inside the macrophages represent lipid droplets.
e right capillary represents the situation in a normal healthy artery; there are only a few microbes and the lipoproteins are able
to traverse the capillary lumen without adherence or obstruction. e left capillary represents the situation in an artery with a
severe microbial invasion; microbial products and autoantibodies stick to the lipoproteins, which aggregate and obstruct the
capillary lumen, leading to local ischemia, microbial growth, and inﬂammation. A monocyte enters the plaque from the arterial
lumen by diapedesis between endothelial cells; another monocyte enters the plaque via vasa vasorum, leading to formation of
foam cell macrophages within the plaque. In the case of an intact immune system, the inﬂammatory area heals and becomes
converted to a ﬁbrous plaque. In the case of an insuﬃcient immune system, microorganisms escape into the tissue and create a
microabscess, the vulnerable plaque.
Flow chart for development of the vulnerable plaque
Microorganisms and spores continually invade the body through the airways, skin and gastro-
intestinal system, and some of them or their toxic products are bound and inactivated by complex
formation with lipoproteins. In the case of a major microbial invasion, the complexes may aggregate.
Hyperhomocysteinemia may increase the complex formation and aggregation through thiolation
of LDL. Autoantibodies against oxidized and thiolated LDL, aggregated LPS, and lipoteichoic
acid, and complexes between sphingolipids and bacterial toxins may further increase the size of the
accumulated lipoprotein complexes. Because of their size and because of high extra-capillary tissue
pressure, the aggregated complexes are trapped within vasa vasorum of the major arteries.
Monocytes entering either via the endothelium or via vasa vasorum are converted to macrophages,
which take up the aggregates by phagocytosis, forming foam cells.
Normal immune system
e foam cells probably move back to the
circulation. Before re-entering the arterial
lumen, they are seen as fatty streaks just
beneath the endothelium. e micro-
organisms and their products are destroyed
inside the macrophages by oxidation. By
this process both cholesterol and LDL are
oxidized as well. In case of a massive
microbial invasion, some of the foam cells
may die, but more macrophages arrive, new
capillaries are formed, and the surrounding
tissue is strengthened by proliferation of
smooth muscle cells and ﬁbrous tissue.
Stable, ﬁbrous plaque
Disturbed immune system
Vasa vasorum become obstructed, leading
to ischemia of the arterial wall, foam cell
death, and release of their content into
artery wall. Microorganisms and endo-
toxins enter the dead tissue, the capillaries
are damaged, erythrocyte extravasation
may occur, and a micro abscess is created.
e vulnerable plaque ruptures. Choles-
terol and microbial products are emptied
into the coronary artery and transported
to the heart and the general circulation.
A thrombus is built at the margins of the
Partial occlusion Total occlusion
Unstable angina Myocardial infarction
Annals of Clinical & Laboratory Science, vol. 39, no. 1, 2009
, an observation needing corroboration from
Fatty streaks are not necessarily the precursors
of atherosclerotic plaques. Fatty streaks are present
in the fetus and are more frequent in early than
late childhood [98,99], presumably reﬂecting a
normal and reversible response to infections.
Hydrodynamic pressure is usually cited as the
reason that atherosclerosis is localized only within
systemic arteries. is explanation is probably
correct, not because the arterial pressure damages
the endothelium, but because the lipoprotein
complexes are trapped more easily in vasa vasorum
of the systemic arteries where the tissue pressure is
much higher than within vasa vasorum around the
veins and the pulmonary arteries. By the same
reasoning, atherosclerotic plaques are localized to
areas of the intimal surface where the hydrodynamic
forces, turbulence of blood ﬂow, and tissue pressure
are especially high, namely at the branching points
of arteries, within tortuous arteries, and within
coronary arteries that are compressed by myocardial
contractions. Whereas normal pulmonary arteries
are generally free of atherosclerosis, they develop
atherosclerotic intimal plaques in various conditions
that lead to pulmonary hypertension. Current
concepts of the anatomy and physiology of vasa
vasorum  emphasize that these vessels are
functionally end arteries, supplying the media to a
depth where blood ﬂow and patency are compressed
by pressure transmitted from the arterial lumen.
e predilection for plaques within systemic
arteries also contradicts the idea that microbes
attack the endothelium directly, because if this
were so, atherosclerosis would be just as common
in veins. Also the focal occurrence of atherosclerotic
lesions is in better accordance with a microbial
genesis, because if elevated LDL cholesterol were
the most important cause, atherosclerosis should be
a more generalized disease.
e increased incidence of cardiovascular events
found after treatment with rofecoxib and other
non-steroidal anti-inﬂammatory drugs 
contradicts the idea that atherosclerosis is caused
by the inﬂammation itself, but it is in accord with
an infectious origin of atherosclerosis, where
inﬂammation is a necessary step for healing. e
ability of HMG-coenzyme A reductase inhibitors
microorganisms and the ensuing inﬂammatory
response, cell death may accelerate and impede
repair processes, creating a vulnerable plaque, the
preferential site for occluding thrombi . e
suggested chain of events is illustrated in Fig. 1 and
in a ﬂow chart (page 10).
Clinical and pathological observations. According
to our hypothesis, LDL-cholesterol does not enter
the artery through the endothelium as suggested
previously, but via the capillary web of vasa vasorum
in and around the arterial walls. Oxidation of LDL
does not take place before LDL has entered the
macrophage but occurs after phagocytosis, as part
of a normal physiological process explaining why
attempts to prevent cardiovascular disease by
antioxidants have been largely unsuccessful.
Some reasons for considering the vulnerable
plaque to be a type of micro-abscess are that more
than one plaque may occur simultaneously [91,92],
and their temperature is higher than that of the
surrounding tissue . Whereas neutrophilic
polymorphonuclear leukocytes, the hallmark of
pyogenic infections, are rare in stable plaques, they
are always found in and around the core of
vulnerable plaques, and there are just as many
neutrophils in the intact as in the ruptured plaques
, contradicting the assumption that their
presence is secondary to rupture.
Our interpretation explains the clinical and
laboratory similarities between myocardial infarc-
tion and myocarditis , and it explains the
frequent occurrence of bacteriemia and sepsis in
myocardial infarction complicated with cardiogenic
shock . It explains why fever, diaphoresis,
leukocytosis and elevation of inﬂammatory markers
in the blood, including CRP, the classical symptoms
of an infectious disease, are common ﬁndings in
myocardial infarction. Chronic elevation of CRP
in patients with atherosclerosis is a risk factor for
myocardial infarction. Our interpretation agrees
with the almost constant ﬁnding of polymorpho-
nuclear leukocytes in the myocardium in acute
myocardial infarction, as well as in infarctions of
other organs. It also explains a recent report of
Chlamydia pneumoniae antigens within cardiomyo-
cytes of patients with fatal myocardial infarction
Vulnerable plaques from lipoprotein aggregates
(statins) to prevent cardiovascular disease, in spite
of their non-steroidal anti-inﬂammatory properties,
is probably attributable to their other pleiotropic
eﬀects, including the enhancement of ﬁbrinolysis
and nitric oxide production, and the inhibition of
An apparent contradiction to our interpretation
is that prevention of cardiovascular disease by
antibiotics has been largely unsuccessful. However,
in these trials patients have usually received a single
antibiotic, chosen because it was eﬀective against
Chlamydia pneumoniae, the organism that has been
studied most intensively, and the trials have been of
relatively short duration.
Chlamydia pneumoniae is not the only microbe
that is found in atherosclerotic plaques. Ott et al
identiﬁed fragments from >50 diﬀerent microbial
species within atherosclerotic plaques, but not a
single one in normal arterial tissue . On
average, each patient had microbial remnants from
12 diﬀerent species; some patients had more, some
had fewer , and other investigators have found
various virus species as well [103-105]. It is highly
unlikely that a single antibiotic could eliminate
>50 diﬀerent microbial species. It is not even likely
that antibiotics could eliminate Chlamydia pneu-
moniae, because this species is able to survive inside
living cells, where they are resistant to the eﬀects of
antibiotics . Furthermore, antibiotics are
generally ineﬀective against viral infections.
Whether the total burden of multiple microbial
invasions or the eﬀect of a single pathogen is the
key to progression remains to be determined .
Evidence that high cholesterol is protective. Since
LDL participates in the immune system, high
plasma cholesterol concentrations should be an
advantage to survival, not a risk. ere is much
evidence that high cholesterol is protective against
infectious diseases. Plasma cholesterol levels have
been found to be inversely associated with total
mortality in the elderly and with mortality from
respiratory and gastrointestinal diseases , most
of which have an infectious origin. Cholesterol
levels are also inversely associated with mortality
after post-operative abdominal infections, inversely
associated with the risk of being admitted to
hospital because of an infectious disease, and
inversely associated with the risk of contracting
HIV and AIDS .
e protective eﬀect of plasma cholesterol levels
is also supported by observations in patients with
inherited disorders of cholesterol metabolism.
Before the year 1900, when infectious disease was
the commonest cause of death, the life span of
people with 50% risk of having familial hyperchol-
esterolemia (FH) was longer than in the general
population . e frequent and severe infections
in children with the extremely low cholesterol levels
that are found in Smith-Lemli-Opitz syndrome are
alleviated by addition of cholesterol to the diet
e lack of an association between the degree
of cholesterol lowering and outcome that were
found in clinical and angiographic trials  could
be explained if the beneﬁts from HMG-coenzyme
A reductase inhibitors (statins) were due to their
pleiotropic eﬀects and not to their inhibition of the
cholesterol synthesis. Even if the lowering of LDL
cholesterol by these drugs were unimportant, there
should have been an exposure-response relationship
between LDL-cholesterol and outcome, because
both the pleiotropic eﬀects and cholesterol lowering
are caused by inhibition of the mevalonate pathway.
A more complete blockage of the mevalonate
pathway should result in stronger pleiotropic eﬀects
and a more pronounced lowering of cholesterol,
and vice versa. As this was not the case, the ﬁndings
imply that high cholesterol is protective and that its
lowering therefore counteracts exposure-response.
is view is in accordance with the trial ﬁndings
and our present interpretation of these ﬁndings.
Similar events in other arteries. If an imbalance
between the microbial burden and the immune
system contributes to coronary heart disease, other
parts of the artery system should be aﬀected as well,
and this seems to be true. Stroke and myocardial
infarction commonly occur in the same patient,
and vulnerable plaques in the carotid arteries are
the starting point of thrombosis in cerebral infarcts
. In a consecutive study of the common iliac,
common carotid, and renal arteries of 49 patients
who died in a hospital, those with a history of
cardiovascular events had 2-4 times more intimal
macrophages and a denser network of vasa vasorum
Annals of Clinical & Laboratory Science, vol. 39, no. 1, 2009
in all of the arteries than atherosclerotic patients
without cardiovascular events . Foam cells
have been identiﬁed adjacent to Bruch´s membrane
of the retina, where their number increases with
the age of patients . Foam cells are also found
in sclerotic glomeruli [113,114]. In addition, adipose
tissue, skin, and muscle specimens from people
over age 70 have about 25% more cholesterol than
those from people age 30, and tendon specimens
have several hundred percent more .
Conclusions. Our interpretation of the origin of
vulnerable plaques explains the molecular, cellular,
and tissue processes resulting in atherosclerosis and
cardiovascular disease. Promoting factors may not
necessarily act by damaging the arterial wall
directly, but rather by inhibiting the immune
system, by facilitating microbial growth, by causing
hyperhomocysteinemia, and by promoting complex
formation and aggregation of homocysteinylated
lipoproteins. Our interpretation is in accord with
several of the classical risk factors. Hyperhomo-
cysteinemia is found in B vitamin deﬁciency,
smoking, hypertension, hypothyroidism, renal
failure, and aging, all classical risk factors for
cardiovascular disease . Mental stress, a well-
known risk factor for cardiovascular disease,
stimulates production of cortisol, and an excess of
cortisol, either from Cushing’s disease of the
adrenal glands or from medical therapy, promotes
infections. Furthermore, mental stress, hostility,
and anger increase the concentration of homo-
cysteine in blood [117,118], potentially promoting
aggregation of LDL particles . Many infectious
diseases are more prevalent in smokers and
diabetics. e suggestion that excess iron is a risk
factor for vascular disease  is also in accordance
with our interpretation, because bacterial growth is
stimulated by the presence of free iron .
erefore, attempts to prevent cardiovascular
disease and prolong life may be more successful if
we understand the fallacies of the lipid hypothesis
 and determine what is harmful to the immune
system and what may strengthen it.
Our interpretation satisﬁes Karl Popper’s
deﬁnition of a scientiﬁc hypothesis, because it is
susceptible to falsiﬁcation:
1. We anticipate that viable microorganisms and
endotoxins in the arterial wall are located within
developing vulnerable plaques.
3. We anticipate that arteries of germ-free, normo-
cholesterolemic animals should have fewer foam
cells and fatty streaks than their conventionally
reared litter mates.
3. A blood culture should be taken in all patients
with unstable angina or myocardial infarction, and
we anticipate that if it is positive, the course of the
disease should be improved with an appropriate
We thank Charles F. Foltz, Medical Media Service,
VA Medical Center, West Roxbury MA, for
assistance in preparing the ﬁgure.
1. Hansson GK, Nilsson J. Introduction: atherosclerosis as
inﬂammation: a controversial concept becomes accepted. J Int
2. Lusis AJ. Atherosclerosis. Nature 2000;407:233-241.
3. Hansson GK, Heistad DD. Two views on plaque rupture.
Arterioscler romb Vasc Biol 2007;27:697.
4. Hansson GK. Inﬂammation, atherosclerosis, and coronary
artery disease. NEJM 2005;352:1685-1695.
5. Reis SE, Holubkov R, Conrad-Smith AJ, Kelsey SF, Sharaf BL,
Reichek N, Rogers WJ, Merz CN, Sopko G, Pepine CJ.
Coronary microvascular dysfunction is highly prevalent in
women with chest pain in the absence of coronary artery
disease: results from the NHLBI WISE study. Am Heart J
6. McCully KS. Vascular pathology of homocysteinemia: implic-
ations for the pathogenesis of arteriosclerosis. Am J Pathol
7. McCully KS. Hyperhomocysteinemia and arteriosclerosis:
historical perspectives. Clin Chem Lab Med 2005;43:980-
8. Ravnskov U. Is atherosclerosis caused by high cholesterol? Q J
9. Ravnskov U. High cholesterol may protect against infections
and atherosclerosis. Q J Med 2003;96:927-934.
10. Miettinen TA, Gylling H. Mortality and cholesterol metabolism
in familial hypercholesterolemia. Long-term follow-up of 96
patients. Arteriosclerosis 1988;8:163-167.
11. Hopkins PN, Stephenson S, Wu LL, Riley WA, Xin Y, Hunt
SE. Evaluation of coronary risk factors in patients with
heterozygous familial hypercholesterolemia. Am J Cardiol
12. Hill JS, Hayden MR, Frohlich J, Pritchard PH. Genetic and
environmental factors aﬀecting the incidence of coronary
artery disease in heterozygous familial hypercholesterolemia.
Arterioscler romb 1991;11:290-297.
13. Ferrières J, Lambert J, Lussier-Cacan S, Davignon J. Coronary
artery disease in heterozygous familial hypercholesterolemia
Vulnerable plaques from lipoprotein aggregates
patients with the same LDL receptor gene mutation. Circulation
14. Neil HAW, Seagroatt V, Betteridge DJ, Cooper MP, Durrington
PN, Miller JP, Seed M, Naoumova RP, ompson GR, Huxley
R, Humphries SE. Established and emerging coronary risk
factors in patients with heterozygous familial hypercholesterol-
aemia. Heart 2004; 90:1431-1437.
15. Jansen AC, van Aalst-Cohen ES, Tanck MW, Cheng S,
Fontecha MR, Li J, Defesche JC, Kastelein JJ. Genetic
determinants of cardiovascular disease risk in familial hyper-
cholesterolemia. Arterioscler romb Vasc Biol 2005;25:1475-
16. Sugrue DD, Trayner I, ompson GR, Vere TV, Dimeson J,
Stirling Y, Meade TW. Coronary artery disease and haemostatic
variables in heterozygous familial hypercholesterolaemia. Br
Heart J 1985;53:265-268.
17. Calara F, Silvestre M, Casanada F, Yean N, Napoli C, Palinski
W. Spontaneous plaque rupture and secondary thrombosis in
apolipoprotein E-deﬁcient and LDL receptor-deﬁcient mice. J
18. Naruszewicz M, Mirkiewicz E, Olszewski AJ, McCully KS.
iolation of low-density lipoprotein by homocysteine
thiolactone causes increased aggregation and altered interaction
with cultured macrophages. Nutr Metab Cardiovas Dis
19. ayer WS. On the cardiac and vascular complications and
sequels of typhoid fever. Bull Johns Hopkins Hosp 1904;
20. Wiesel J. Die Erkrankungen arterieller Gefässe im Verlaufe
akuter Infektionen. II Teil. Z Heilkunde 1906; 27:262-294.
21. Osler W. Diseases of the arteries. In: Modern Medicine: its
Practice and eory (Osler W, Ed), Lea & Fibiger, Philadelphia,
1908; pp 426-447.
22. Klotz O, Manning MF. Fatty streaks in the intima of arteries.
J Pathol Bacteriol 1911;16:211-220.
23. Grayston JT, Kuo CC, Campbell LA, Benditt EP. Chlamydia
pneumoniae strain TWAR and atherosclerosis. Eur Heart J
24. Melnick JL, Adam E, Debakey ME. Cytomegalovirus and
atherosclerosis. Eur Heart J 1993;Suppl K:30-38.
25. Nicholson AC, Hajjar DP. Herpesvirus in atherosclerosis and
thrombosis. Etiologic agents or ubiquitous bystanders? Arterio-
scler romb Vasc Biol 1998;18:339-348.
26. Ismail A, Khosravi H, Olson H. e role of infection in athero-
sclerosis and coronary artery disease. A new therapeutic target.
Heart Dis 1999;1:233-240.
27. Kuvin JT, Kimmelstiel MD. Infectious causes of atherosclerosis.
Am Heart J 1999;137:216-226.
28. Madjid M, Miller CC, Zarubaev VV, Marinich IG, Kiselev OI,
Lobzin YV, Filippov AE, Casscells SW. Inﬂuenza epidemics
and acute respiratory disease activity are associated with a surge
in autopsy-conﬁrmed coronary heart disease death: results
from 8 years of autopsies in 34,892 subjects. Eur Heart J
29. Smeeth L, omas SL, Hall AJ, Hubbard R, Farrington P,
Vallance P. Risk of myocardial infarction and stroke after
acute infection or vaccination. NEJM 2004;351:2611-2618.
30. Valtonen V, Kuikka A, Syrjanen J. rombo-embolic compli-
cations in bacteremic infections. Eur Heart J 1993;14Suppl
31. Spahr A, Klein E, Khuseyinova N, Boeckh C, Muche R, Kunze
M, Rothenbacher D, Pezeshki G, Hoﬀmeister A, Koenig W.
Periodontal infections and coronary heart disease: role of
periodontal bacteria and importance of total pathogen burden
in the Coronary Event and Periodontal Disease (CORODONT)
study. Arch Intern Med 2006;166:554-549.
32. Espinola-Klein C, Rupprecht HJ, Blankenberg S, Bickel C,
Kopp H, Victor A, Hafner G, Prellwitz W, Schlumberger W,
Meyer J. Impact of infectious burden on progression of carotid
atherosclerosis. Stroke 2002;33:2581-2586.
33. Pesonen E. Infection and intimal thickening: evidence from
coronary arteries in children. Eur Heart J 1994;15Suppl C:57-
34. Liuba P, Persson J, Luoma J, Yla-Herttuala S, Pesonen E. Acute
infections in children are accompanied by oxidative modiﬁ-
cation of LDL and decrease of HDL cholesterol, and are
followed by thickening of carotid intima-media. Eur Heart J
35. Todd EW, Coburn AF, Hill AB. Antistreptolysin S titres in
rheumatic fever. Lancet 1939;2:1213-1217.
36. Stollerman GH, Bernheimer AW. Inhibition of streptolysin S
by the serum of patients with rheumatic fever and acute
streptococcal pharyngitis. J Clin Invest 1950;29:1147-1155.
37. Humphrey JH. e nature of antistreptolysin S in the sera of
man and of other species; the lipoprotein properties of
antistreptolysin S. Br J Exp Pathol 1949;30:365-375.
38. Stollerman GH, Bernheimner AW, MacLeod CM. e
association of lipoproteins with the inhibition of streptolysin S
by serum. J Clin Invest 1950;29:1636-1645.
39. Skarnes RC. In vivo interaction of endotoxin with a plasma
lipoprotein having esterase activity. J Bacteriol 1968;95:2031-
40. Shortridge KF, Ho WK, Oya A, Kobayashi M. Studies on the
inhibitory activities of human serum lipoproteins for Japanese
encephalitis virus. Southeast Asian J Trop Med Public Health
41. Whitelaw DD, Birkbeck TH. Inhibition of staphylococcal
delta-hemolysin by human serum lipoproteins. FEMS Micro-
biology Letters 1978;3:335-339.
42. Freudenberg MA, Galanos C. Interaction of lipopolysaccharides
and lipid A with complement in rats and its relation to endo-
toxicity. Infect Immun 1978;19:875-882.
43. Ulevitch RJ, Johnston AR, Weinstein DB. New function for
high density lipoproteins. Isolation and characterization of a
bacterial lipopolysaccharide-high density lipoprotein complex
formed in rabbit plasma. J Clin Invest 1981;67:827-837.
44. Bhakdi S, Tranum-Jensen J, Utermann G, Fussle R. Binding
and partial inactivation of Staphylococcus aureus alpha-toxin by
human plasma low density lipoprotein. J Biol Chem 1983;258:
45. Seganti L, Grassi M, Mastromarino P, Pana A, Superti F, Orsi
N. Activity of human serum lipoproteins on the infectivity of
rhabdoviruses. Microbiologica 1983;6:91-99.
46. Van Lenten BJ, Fogelman AM, Haberland ME, Edwards PA.
e role of lipoproteins and receptor-mediated endocytosis in
the transport of bacterial lipopolysaccharide. PNAS USA
47. Huemer HP, Menzel HJ, Potratz D, Brake B, Falke D,
Utermann G, Dierich MP. Herpes simplex virus binds to human
serum lipoprotein. Intervirology 1988;29:68-76.
48. Flegel WA, Wölpl A, Männel DN, Northoﬀ H. Inhibition of
endotoxin-induced activation of human monocytes by human
lipoproteins. Infect Immun 1989;57:2237-2245.
49. Cavaillon JM, Fitting C, Haeﬀner-Cavaillon N, Kirsch SJ,
Warren HS. Cytokine response by monocytes and macrophages
to free and lipoprotein-bound lipopolysaccharide. Infect
50. Northoﬀ H, Flegel WA, Yurttas R, Weinstock C. e role of
lipoproteins in inactivation of endotoxin by serum. Beitr
51. Superti F, Seganti L, Marchetti M, Marziano ML, Orsi N. SA-
11 rotavirus binding to human serum lipoproteins. Med
Microbiol Immunol 1992;181:77-86.
Annals of Clinical & Laboratory Science, vol. 39, no. 1, 2009
52. Weinstock C, Ullrich H, Hohe R, Berg A, Baumstark MW,
Frey I, Northoﬀ H, Flegel WA. Low density lipoproteins
inhibit endotoxin activation of monocytes. Arterioscler romb
53. Flegel WA, Baumstark MW, Weinstock C, Berg A, Northoﬀ
H. Prevention of endotoxin-induced monokine release by
human low- and high-density lipoproteins and by apolipoprotein
A-1. Infect Immun 1993;61:5140-5146.
54. Feingold KR, Funk JL, Moser AH, Shigenaga JK, Rapp JH,
Grunfeld C. Role for circulating lipoproteins in protection
from endotoxin toxicity. Infect Immun 1995;63:2041-2046.
55. Netea MG, Demacker PNM, Kullberg BJ, Boerman OC,
Verschueren I, Stalenhoef AF, van der Meer JW. Low-density
lipoprotein receptor-deﬁcient mice are protected against lethal
endotoxemia and severe Gram-negative infections. J Clin
56. Hudgins LC, Parker TS, Levine DM, Gordon BR, Saal SD,
Jiang XC, Seidman CE, Tremaroli JD, Lai J, Rubin AL. A
single intravenous dose of endotoxin rapidly alters serum lipo-
proteins and lipid transfer proteins in normal volunteers. J
Lipid Res 2003;44:1489-1498.
57. Guyton JR, Klemp KF. Transitional features in human athero-
sclerosis. Intimal thickening, cholesterol clefts, and cell loss in
human aortic fatty streaks. Am J Pathol 1993;143:1444-1457.
58. Van Amersfoort ES, Van Berkel TJC, Kuiper J. Receptors,
mediators, and mechanisms involved in bacterial sepsis and
septic shock. Clin Microbiol Rev 2003;16:379-414.
59. Khovidhunkit W, Kim M-S, Memon RA, Shigenaga JK, Moser
AH, Feingold KR, Grunfeld C. Eﬀects of infection and
inﬂammation on lipid and lipoprotein metabolism: mechanisms
and consequences to the host. J Lipid Res 2004;45:1169-1196.
60. Heinecke JW, Suits AG, Aviram M, Chait A. Phagocytosis of
lipase-aggregated low density lipoprotein promotes macrophage
foam cell formation. Sequential morphological and biochemical
events. Arterioscler romb 1991;11:1643-1651.
61. Kalayoglu MV, Indrawati, Morrison RP, Morrison SG, Yuan Y,
Byrne GI. Chlamydial virulence determinants in atherogenesis:
the role of chlamydial lipopolysaccharide and heat shock
protein 60 in macrophage-lipoprotein interactions. J Infect Dis
62. Qi M, Miyakawa H, Kuramitsu HK. Porphyromonas gingivalis
induces murine macrophage foam cell formation. Microb
63. Madjid M, Vela D, Khalili-Tabrizi H, Casscells SW, Litovsky
S. Systemic infections cause exaggerated local inﬂammation in
atherosclerotic coronary arteries: clues to the triggering eﬀect
of acute infections on acute coronary syndromes. Tex Heart
Inst J 2007;34:11-18.
64. Welch CL, Sun Y, Arey BJ, Lemaitre V, Sharma N, Ishibashi
M, Sayers S, Li R, Gorelik A, Pleskac N, Collins-Fletcher K,
Yasuda Y, Bromme D, D’Armiento JM, Ogltree ML, Tall AR.
Spontaneous thrombosis and medial degeneration in Apo3-/-,
Npc1-/- mice. Circulation 2007;116:2444-2452.
65. Noble NL, Boucek RJ, Kao KY. Biochemical observations of
human atheromatosis: analysis of aortic intima. Circulation
66. Bonnefont-Rousselot D, erond P, Beaudeux JL, Peynet J,
Legrand A, Delattre J. High density lipoproteins (HDL) and
the oxidative hypothesis of atherosclerosis. Clin Chem Lab
67. Fabricant CG, Krook L, Gillespie JH. Virus-induced cholesterol
crystals. Science 1973;181:566-567.
68. Benesch R, Benesch RE. iolation of proteins. PNAS USA
69. Vidal M, Sainte-Marie J, Philippot J, Bienvenue A. iolation
of low-density lipoproteins and their interactions with L2C
leukemic lymphocytes. Biochimie 1986;68:723-730.
70. Ferguson E, Parthasarathy S, Joseph J, Kalyanaraman B.
Generation and initial characterization of a novel polyclonal
antibody directed against homocysteine thiolactone-modiﬁed
low density lipoprotein. J Lipid Res 1998;39:925-933.
71. Undas A, Jankowski M, Twardowska M, Padjas A, Jakubowski
H, Szczeklik A. Antibodies to N-homocysteinylated albumin
as a marker for early-onset coronary artery disease in men.
romb Haemost 2005;93:346-350.
72. Yang X, Gao Y, Zhou J, Yang Y, Wang J, Song L, Liu Y, Xu H,
Chen Z, Hui R. Plasma homocysteine thiolactone adducts
associated with risk of coronary heart disease. Clin Chim Acta
73. Perla-Kajan J, Twardowski T, Jakubowski H. Mechanisms of
homocysteine toxicity in humans. Amino Acids 2007;32:561-
74. Lazzerini PE, Capecchi PL, Selvi E, Lorenzini S, Bisogno S,
Galezzi M, Pasini FL. Hyperhomocysteinemia, inﬂammation
and autoimmunity. Autoimmun Rev 2007;6:503-509.
75. Chang MK, Binder CJ, Torzewski M, Witztum JL. C-reactive
protein binds to both oxidized LDL and apoptotic cells through
recognition of a common ligand: phosphoryl choline of
oxidized phospholipids. PNAS USA 2002;99:13043-13048.
76. Uusitupa MI, Niskanen L, Luoma J, Vilja P, Mercuri M,
Rauramaa R, Ylä-Herttuala S. Autoantibodies against oxidized
LDL do not predict atherosclerotic vascular disease in non-
insulin-dependent diabetes mellitus. Arterioscler romb Vasc
77. Leinonen JS, Rantalaiho V, Laippala P, Wirta O, Pasternack A,
Alho H, Jaakkola O, Ylä-Herttuala S, Koivula T, Lehtimäki T.
e level of autoantibodies against oxidized LDL is not
associated with the presence of coronary heart disease or
diabetic kidney disease in patients with non-insulin-dependent
diabetes mellitus. Free Radic Res 1998;29:137-141.
78. Wilson PW, Ben-Yehuda O, McNamara J, Massaro J, Witztum
J, Reaven PD. Autoantibodies to oxidized LDL and
cardiovascular risk: the Framingham Oﬀspring Study. Athero-
79. Mayr M, Kiechl S, Tsimikas S, Miller E, Sheldon J, Willeit J,
Witztum JL, Xu Q. Oxidized low-density lipoprotein auto-
antibodies, chronic infections, and carotid atherosclerosis in a
population-based study. J Am Coll Cardiol 2006;47:2436-
80. Tsimikas S, Aikawa M, Miller RJ Jr, Miller ER, Torzewski M,
Lentz SR, Bergmark C, Heistad DD, Libby P, Witztum JL.
Increased plasma oxidized phospholipid:apolipoprotein B-100
ratio with concomitant depletion of oxidized phospholipids
from atherosclerotic lesions after dietary lipid-lowering: a
potential biomarker of early atherosclerosis regression.
Arterioscler romb Vasc Biol 2007;27:175-181.
81. Schumacher M, Eber B, Tatzber F, Kaufmann P, Halwachs G,
Fruhwald FM, Zweiker R, Esterbauer H, Klein W. Transient
reduction of autoantibodies agains
t oxidized LDL in patients
with acute myocardial infarction. Free Radic Biol Med 1995;
82. Su J, Georgiades A, Wu R, ulin T, de Faire U, Frostegård J.
Antibodies of IgM subclass to phosphorylcholine and oxidized
LDL are protective factors for atherosclerosis in patients with
hypertension. Atherosclerosis 2006;188:160-166.
83. Sjoberg BG, Su J, Dahlbom I, Gronlund H, Wikstrom M,
Hedblad B, Berglund G, de Faire U, J, Frostegård. Low levels
of IgM antibodies against phosphorylcholine - a potential risk
marker for ischemic stroke in men. Atherosclerosis 2007,
84. Ramirez J. Isolation of Chlamydia pneumoniae from the
coronary artery of a patient with atherosclerosis. Ann Int Med
Vulnerable plaques from lipoprotein aggregates
85. Jackson LA, Campbell LA, Kuo CC, Rodriguez DI, Lee A,
Grayston JT. Isolation of Chlamydia pneumoniae from a carotid
endarterectomy specimen. J Infect Dis 1997;176:292-295.
86. Maass M, Bartels C, Engel PM, Mamat U, Sievers HH.
Endovascular presence of viable Chlamydia pneumoniae is a
common phenomenon in coronary artery disease. J Am Coll
87. Kuo C-C, Shor A, Campbell LA, Fukushi H, Patton DL,
Grayston JT. Demonstration of Chlamydia pneumoniae in
atherosclerotic lesions of coronary arteries. J Inf Dis 1993;
88. Campbell LA, O’Brien ER, Capuccio AL, Kuo C-C, Wang S-
P, Stewart D, Patton DL, Cummings PK, Grayston JT.
Detection of Chlamydia pneumoniae TWAR in human
coronary atherectomy tissues. J Inf Dis 1995;172:285-288.
89. Vink A, Pasterkamp G, Poppen M, Schonfeld AH, deKleijn
DPV, Roholl PJM, Fontijn J, Plomp S, Borst C. e adventitia
of atherosclerotic coronary arteries frequently contains
Chlamydia pneumoniae. Atherosclerosis 2001;157:117-122.
90. Grattan MT, Moreno-Cabral CE, Starnes VA, Oyer PE,
Stinson EB, Shumway NE. Cytomegalovirus infection is
associated with cardiac allograft rejection and atherosclerosis.
91. Falk E. Plaque rupture with severe pre-existing stenosis
precipitating coronary thrombosis. Characteristics of coronary
atherosclerotic plaques underlying fatal occlusive thrombi. Br
Heart J 1983;50:127-134.
92. Buﬀon A, Biasucci LM, Liuzzo G, D’Onofrio G, Crea F,
Maseri A. Widespread coronary inﬂammation in unstable
angina. NEJM 2002;347:5-12.
93. Madjid M, Naghavi M, Malik BA, Litovsky S, Willerson JT,
Casscells SW. ermal detection of vulnerable plaque. Am J
94. 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.
95. Costantini M, Tritto C, Licci E, Sticchi G, Capone S, Montiaro
A, Bruno A, Nuzzaci G, Picano E. Myocarditis with ST-
elevation myocardial infarction presentation in young men. A
case series of 11 patients. Int J Cardiol 2005;101:157-158.
96. Kohsaka S, Menon V, Lowe AM, Lange M, Dzavik V, Sleeper
LA, Hochman JS; SHOCK Investigators. Systemic inﬂam-
matory response syndrome after acute myocardial infarction
complicated by cardiogenic shock. Arch Intern Med 2005;
97. Spagnoli LG, Pucci S, Bonanno E, Cassone A, Sesti F, Ciervo
A, Mauriello A. Persistent Chlamydia pneumoniae infection of
cardiomyocytes is correlated with fatal myocardial infarction.
Am J Pathol 2007;170:33-42.
98. Stary HC. Macrophages, macrophage foam cells, and eccentric
intimal thickening in the coronary arteries of young children.
99. Stary HC. Evolution and progression of atherosclerotic lesions
in coronary arteries of children and young adults. Arterio-
sclerosis 1989;9(1 Suppl):I19-32.
100. Ritman EL, Lerman A. e dynamic vasa vasorum. Cardiovasc
101. Johnsen SP, Larsson H, Tarone RE, McLaughlin JK, Norgard
B, Friis S, Sorensen HR. Risk of myocardial infarction among
users of rofecoxib, celecoxib, and other NSAIDs: a population-
based case-control study. Arch Intern Med 2005;165:978-984.
102. Ott SJ, El Mokhtari NE, Musfeldt M, Hellmig S, Freitag S,
Rehman A, Kuhbacher T, Nikolaus S, Namsolleck P, Blaut M,
Hampe J, Sahly H, Reinecke A, Haake N, Gunther R, Kruger
D, Lins M, Herrmann G, Folsch UR, Simon R, Schreiber S.
Detection of diverse bacterial signatures in atherosclerotic
lesions of patients with coronary heart disease. Circulation
103. Melnick JL, Petrie BL, Dreesman GR, Burek J, McCollum
CH, DeBakey ME. Cytomegalovirus antigen within human
arterial smooth muscle cells. Lancet 1983;2:644-647.
104. Pampou SY, Gnedoy SN, Bystrevskaya VB, Smirnov VN,
Chazov EI, Melnick JL, DeBakey ME. Cytomegalovirus genome
and the immediate-early antigen in cells of diﬀerent layers of
human aorta. Virchows Arch 2000;436:539-552.
105. Shi Y, Tokunaga O. Chlamydia pneumoniae and multiple
infections in the aorta contribute to atherosclerosis. Pathol Int
106. Gieﬀers J, Füllgraf H, Jahn J, Klinger M, Dalhoﬀ K, Katus
HA, Solbach W, Maass M. Chlamydia pneumoniae infection in
circulating human monocytes is refractory to antibiotic
treatment. Circulation 2001;103:351-356.
107. Katz JT, Shannon RP. Bacteria and coronary atheroma: more
ﬁngerprints but no smoking gun. Circulation 2006;113:920-
108. Sijbrands EJ, Westendorp RG, Defesche JC, de Meier PH,
Smelt AH, Kastelein JJ. Mortality over two centuries in large
pedigree with familial hypercholesterolaemia: family tree
mortality study. Brit Med J 2001;322:1019-1023.
109. Elias ER, Irons MB, Hurley AD, Tint GS, Salen G. Clinical
eﬀects of cholesterol supplementation in six patients with the
Smith-Lemli-Opitz syndrome (SLOS). Am J Med Genet
110. Yuan C, Mitsumori LM, Beach KW, Maravilla KR. Carotid
atherosclerotic plaque: noninvasive MR characterization and
identiﬁcation of vulnerable lesions. Radiology 2001;221:285-
111. Fleiner M, Kummer M, Mirlacher M, Sauter G, Cathomas G,
Krapf R, Biedermann BC. Arterial neovascularization and
inﬂammation in vulnerable patients: early and late signs of
symptomatic atherosclerosis. Circulation 2004;110:2843-
112. Curcio CA, Millican CL, Bailey T, Kruth HS. Accumulation
of cholesterol with age in human Bruch’s membrane. Invest
Ophthalmol Vis Sci 2001;42:265-274.
113. Schonholzer KW, Waldron M, Magil AB. Intraglomerular
foam cells and human focal glomerulosclerosis. Nephron 1992;
114. Lee HS, Kruth HS. Accumulation of cholesterol in the lesions
of focal segmental glomerulosclerosis. Nephrology 2003;8:224-
115. Crouse JR, Grundy SM, Ahrens EH. Cholesterol distribution
in the bulk tissues of man: variation with age. J Clin Invest
116. McCully KS. Homocysteine, vitamins, and vascular disease
prevention. Am J Clin Nutr 2007;86(Suppl):1563S-1568S.
117. Stoney CM. Plasma homocysteine levels increase in women
during psychological stress. Life Sciences 1999;64:2359-2365.
118. Stoney CM, Engebretson TO. Plasma homocysteine concen-
trations are positively associated with hostility and anger. Life
119. Sullivan JL. e iron paradigm of ischemic heart disease. Am
Heart J 1989,117:1177-1188.
120. Bullen JJ, Rogers HJ, Spalding PB, Ward CG. Natural
resistance, iron and infection: a challenge for clinical medicine.
J Med Microbiol 2006;55:251-258.
121. Ravnskov U. e fallacies of the lipid hypothesis. Scand Cardio-
vasc J 2008;42:236-239.
Annals of Clinical & Laboratory Science, vol. 39, no. 1, 2009