From the Departments of Internal Medicine and Pharmacology,
Cardiovascular Center and Center on Aging, University of Iowa College of
Medicine, Iowa City.
Correspondence to Donald Heistad, MD, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa 52242. E-mail donald-heistad{at}uiowa.edu
Methods and Results—Segments of thoracic aorta and left
circumflex coronary artery were obtained from 3 groups of
cynomolgus monkeys: normal, atherosclerotic, and regression. Samples of
human coronary arterial atherosclerotic lesions
were obtained from directional atherectomy. Sections were stained for
Ang II with 3 different polyclonal rabbit anti–human Ang II antisera.
In aorta and coronary arteries from normal monkeys, there was
no or minimal anti–Ang II staining in endothelial
cells. All sections from atherosclerotic monkeys displayed discrete,
localized regions of staining for Ang II in intima-media.
Macrophages were present throughout the atherosclerotic
intima-media, and anti–Ang II staining appeared to colocalize with
macrophages. All human coronary atherectomy samples
stained positive for Ang II and macrophages. Staining for both
Ang II and macrophages was observed in vascular lesions from
all 5 monkeys after regression of atherosclerosis, but
staining was less extensive than in atherosclerotic blood vessels from
monkeys.
Conclusions—These findings suggest that Ang II is present in
atherosclerotic lesions in monkeys and humans, colocalizes with
macrophages in intima-media of atherosclerotic vessels from
monkeys, and decreases in lesions in monkeys with regression of
atherosclerosis.
The first goal of this study was to determine whether
monocyte/macrophages in atherosclerotic lesions contain Ang II.
We adapted an immunocytochemical technique that was used previously to
study circulating monocytes.4 The validity of the
immunocytochemical technique was supported by measurements of Ang II in
monocytes with radioimmunoassay.4 In this study,
we examined aorta and coronary arteries from monkeys with
diet-induced atherosclerosis and atherectomy samples
from human coronary arteries.
Regression of atherosclerosis in primates results in
reabsorption of lipids from the intima and reduction of intimal
thickening.7 8 During regression of
atherosclerosis, many monocyte/macrophages
disappear from the vessel wall.9 The second goal
of this study was to determine whether regression of
atherosclerosis in monkeys is accompanied by a decrease
in Ang II–containing cells in intimal lesions.
Monkeys were sedated with ketamine (15 mg/kg IM) and euthanized
with intravenous KCl. Segments of thoracic aorta and left
circumflex coronary artery were removed and cleared of adherent
fat, fixed in 10% formaldehyde, and embedded in paraffin. Serial
sections were stained for the presence of Ang II, macrophages,
and smooth muscle cells (SMCs).
Samples of human atherosclerotic coronary artery were obtained
during clinically indicated directional atherectomy in 5 patients
(AtheroCath, Devices for Vascular Intervention, Inc). All procedures
were approved by the Animal Care and Human Use Committee at the
University of Iowa.
Immunohistochemical Staining of Ang II
The immunoreaction was performed by an alkaline phosphatase method with
3 different polyclonal rabbit anti–human Ang II antisera. The
immunoreaction, performed with antiserum from Peninsula Laboratories
Inc, was similar to that used for staining of circulating
leukocytes,4 except that the primary antibody was
diluted 1:500 in 1% normal goat serum and 0.1% BSA and tissue
sections were incubated for 60 minutes at 37°C. The second antiserum
("Denise") was obtained from Martin Cassell (University of Iowa, a
gift from D. Ganten), and the third antiserum ("RAB 82") was a gift
from Donna Farley (University of Iowa). Each antiserum was diluted
1:500 in 1% normal goat serum, and tissue sections were incubated for
60 minutes at 37°C. The Denise antiserum has been previously tested
for cross-reactivity and sensitivity.10
After further washing, slides were incubated with biotinylated
anti-rabbit secondary antibody (Vector Laboratories) and conjugated
with avidin. Vector Blue was used as a chromogenic
substrate (0.1 mol/L Tris buffer, pH 8.2). Sections were counterstained
with nuclear fast red. As positive controls for Ang II, we used
juxtaglomerular cells of normal monkey kidney and sections
of normal monkey aorta incubated with 10-11 to
10-9 mol/L human Ang II (Peninsula Laboratories
Inc) for 60 minutes.11 12 Negative controls were
performed by substituting normal rabbit serum for primary antiserum and
omitting the primary antiserum from the 1% normal goat serum.
The specificity of the antisera for Ang II was tested by solid-phase
preabsorption with Ang II bound to Sepharose beads, similar to the
procedure of Swaab and Poole13 and Imboden et
al.14 Conjugation of Ang II to
NHS-activated Sepharose (Pharmacia) was performed according to
the manufacturer's instructions. Briefly, 300 µL of Sepharose slurry
was incubated with Ang II (100 µL of 10 mg/mL of conjugation buffer,
Peninsula) or conjugation buffer (negative control) at room temperature
for 3 hours with frequent mixing. One milliliter of 0.1 mol/L Tris, 0.5
mol/L NaCl, pH 8.5, was added to each slurry and incubated at room
temperature for 2 hours with frequent mixing. The slurries were
centrifuged at 1000 rpm for 1 minute to collect the Ang
II–coupled Sepharose beads. Antiserum (15 µL, Peninsula) was added
to the first Ang II–conjugated or negative control Sepharose beads and
incubated at room temperature for 1 hour with frequent mixing. The
slurries were centrifuged at 1000 rpm for 1 minute, and the
supernatant was collected. The preabsorbed antiserum or negative
control was then used for immunohistochemical staining as described
previously. In another experiment, preabsorbed antiserum or negative
control was incubated with appropriate Sepharose beads and
centrifuged 2 more times, for a total of 3 incubations, then
used for immunostaining.
Immunohistochemical Staining of Macrophages and
SMCs
To quantify Ang II–containing cells in atherosclerotic lesions, total
cells and cells that stained positively to the anti–Ang II antisera
were counted in the thickened intima-media of atherosclerotic and
regressive arteries. Endothelial cells were not
counted. There were no cells between the endothelium
and internal elastic lamina of any arteries from normal monkeys. Four
high-power fields (x400) were chosen at evenly spaced radial locations
within lesions of atherosclerotic and regression monkey vessels. If the
lesion was sufficiently large, another field was counted. On average,
500 to 600 cells were counted in each section. Only 1 high-power field
was counted in each of 4 to 5 sections from each human coronary
atherectomy sample.
Values for normal, atherosclerotic, and regressive arteries were
compared by a 1-way ANOVA, followed by Bonferroni's corrected
t test. A value of P<0.05 was considered
statistically significant.
Ang II in Monkey Arteries
In atherosclerotic aortas and coronary arteries, Ang II was
localized in the fibrofatty region of the thickened intima and
immediately beneath the endothelium. Anti–Ang II
staining was observed both within cells and extracellularly throughout
the lesion and adventitia (Figure 1B
We used liquid-phase preabsorption to determine whether excess Ang II
would prevent binding of the antiserum for Ang II to tissue. We were
not able to prevent binding of the Ang II antiserum to tissue using 10
µg/mL to 10 mg/mL of unconjugated Ang II. This finding is similar to
that of Imboden et al14 for Ang II antiserum and
Swaab and Poole13 for other antisera
(antioxytocin and antivasopressin), who also were unable to
successfully preabsorb the antisera with excess peptide (Ang II,
oxytocin, or vasopressin).
Solid-phase preabsorption was used to examine specificity of the
Peninsula antiserum for Ang II. Antiserum for Ang II that was
preabsorbed once by solid-phase preabsorption with Ang II bound to
Sepharose beads did not produce cell-associated staining in the
intima-media. Some diffuse blue staining was observed in the
adventitia, media, and intima-media with antiserum that was preabsorbed
once. Antiserum that was preabsorbed 3 times did not produce any
immunostaining, either cell-associated or diffuse.
Incubation of antiserum with the negative control Sepharose beads (with
no conjugated Ang II) resulted in staining that was similar to staining
observed in sections with primary Ang II antiserum.
After regression of atherosclerosis, cell-associated
anti–Ang II staining appeared to decrease compared with
atherosclerotic arteries, and extracellular stain was also reduced
(Figure 1C
Macrophages and SMCs
Intima-media of atherosclerotic lesions contained cells with Ang II
(Figure 3A
Human Coronary Atherectomy Samples
Quantification of Cells
There were virtually no Ang II–containing cells in normal vessels
(Figure 5
Atherectomy samples from human coronary arteries contained a
large number of Ang II–containing cells (57±15% of total cells)
(Figure 5
In a previous study in which immunocytochemistry was used to
demonstrate Ang II in circulating monocytes,4 we
also used radioimmunoassay to quantify the amount of Ang II. With
radioimmunoassay, we demonstrated that there is indeed a large amount
of Ang II in monocytes (about 2300 fmol/mg protein). In the present
study, it was not possible to quantify the amount of Ang II in lesions,
but dense staining in >50% of macrophages in vessels of
atherosclerotic monkeys and >50% of cells in lesions of
atherosclerotic humans suggests that atherosclerotic lesions contain a
large amount of Ang II.
Three approaches were used to examine specificity of the antisera for
Ang II. First, we used 3 different antisera. All antisera demonstrated
a similar pattern of staining. Second, we used liquid-phase
preabsorption with excess Ang II. Excess Ang II did not prevent
staining in tissue sections by Ang II antisera, as discussed below.
Third, we performed solid-phase preabsorption of antiserum with Ang II
conjugated to Sepharose beads. Cell-associated staining in intima-media
was prevented with antiserum that was preabsorbed once by solid-phase
preabsorption, but some diffuse staining remained. Cell-associated and
diffuse staining both were prevented with antiserum that was
preabsorbed 3 times by Ang II conjugated to Sepharose beads. This
finding strongly suggests that cell-associated staining is specific for
Ang II and suggests that diffuse staining is likely to be specific for
Ang II.
In contrast to the effectiveness of the solid-phase preabsorption in
preventing staining in tissue sections, we were not able to prevent
anti–Ang II staining by adding excess Ang II to the antiserum before
exposure to tissue. These findings are similar to those of other
investigators.13 14 It has been
proposed14 that antiserum may bind preferentially
to conjugated Ang II in fixed tissues. Because Ang II is conjugated in
tissue by formaldehyde fixation, the Ang II in the fixed tissue may
resemble the conformation of Ang II conjugated to Sepharose beads.
Thus, we and others14 have observed that
pretreatment of anti–Ang II antiserum with Ang II conjugated to
Sepharose beads prevented staining in tissues, but unbound Ang II did
not prevent staining. These findings are compatible with the concept
that the Ang II antiserum preferentially interacts with conjugated Ang
II and is able to detect conjugated Ang II in tissue.
Ang II in Atherosclerotic Lesions
Cellular and extracellular Ang II was also identified in samples from
human atherosclerotic coronary arteries. It was not possible to
determine in atherectomy samples whether Ang II–containing cells
colocalized with specific types of cells, because features of adjacent
sections were difficult to identify and orientation within a vessel was
not feasible.
The origin of Ang II in macrophages in blood vessels is not
clear. It is not known whether Ang II is produced from
angiotensinogen within monocyte/macrophages or
whether it is taken up from plasma by monocytes or
monocyte/macrophages. Monocytes contain cathepsin
G,16 17 18 which cleaves
angiotensinogen directly to Ang II. Also,
macrophages synthesize
angiotensins19 and contain
ACE20 21 and thus may generate intracellular Ang
II. In addition, monocyte/macrophages have receptors for Ang
II,6 22 23 which take up Ang II by
endocytosis.23 Thus, monocyte/macrophages
may be capable of either taking up Ang II from plasma or synthesizing
Ang II intracellularly.
Effect of Regression on Ang II in Lesions
Limitations of Method for Immunohistochemical Staining for Ang
II
In contrast to the cell-associated staining, it is difficult to know
whether diffuse blue staining is specific for Ang II. After incubation
of monkey coronary artery with purified human Ang II, there was
an increase in diffuse blue staining in the adventitia and a less
pronounced increase in diffuse blue staining in the intima-media and
media. Antiserum preabsorbed 3 times with conjugated Ang II prevented
anti–Ang II staining. Thus, it seems likely that the diffuse blue
extracellular stain was specific for Ang II.
Anti–Ang II staining was patchy in endothelium of
normal monkey blood vessels. Endothelial cells contain
ACE and several components of the renin-angiotensin
system,25 which suggests that the staining in
normal monkey blood vessels is Ang II. Moreover, there was no staining
in endothelial cells after solid-phase preabsorption
and in experiments in which normal rabbit serum was substituted for the
primary antibody. Thus, staining of endothelium in
normal monkey blood vessels probably indicates Ang II.
Because each Ang II antiserum reacts completely with Ang III, we cannot
exclude the possibility that Ang III is also present in
atherosclerotic aortas and coronary arteries from monkeys and
humans.
Possible Role of Ang II in Atherosclerotic Lesions
Ang II appears to be chemotactic for adherent
monocytes.29 30 31 Thus, Ang II may also stimulate
infiltration and accumulation of macrophages in atherosclerotic
lesions. Furthermore, Ang II–modified LDL may be taken up by
macrophages via the scavenger receptor at an enhanced
rate.6 Thus, Ang II may contribute to vascular
dysfunction in atherosclerosis not only through
stimulation of proliferation of SMCs but also by increasing
accumulation of cholesterol and formation of foam
cells.
In conclusion, these findings demonstrate a potentially important and
previously unrecognized source of Ang II in atherosclerotic lesions.
The presence of Ang II in cells within the intima-media of
atherosclerotic blood vessels and the decrease during regression may
have important implications for the role of Ang II in the
pathophysiology of atherosclerosis.
Received January 7, 1998;
revision received February 18, 1998;
accepted March 17, 1998.
© 1998 American Heart Association, Inc.
Basic Science Reports
Evidence That Macrophages in Atherosclerotic Lesions Contain Angiotensin II
Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
Background—We have reported that
human mononuclear leukocytes contain large amounts of
angiotensin II (Ang II). The goal of the present study
was to test the hypothesis that Ang II is present in
monocyte/macrophages in atherosclerotic lesions.
Key Words: angiotensin • cells • immunohistochemistry • atherosclerosis
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
When circulating
mononuclear leukocytes enter a tissue, they become macrophages.
Macrophages appear to play a pivotal role in development and
progression of atherosclerotic lesions.1
Mononuclear leukocytes synthesize
angiotensinogen,2 and when
mononuclear leukocytes become macrophages, ACE is
upregulated.3 Circulating mononuclear leukocytes
in humans contain angiotensin I and a large amount of
angiotensin II (Ang II).4 Thus, it
seems likely that macrophages in atherosclerotic lesions might
contain Ang II. This finding would be of interest, in part because the
renin-angiotensin system may contribute to development of
atherosclerotic lesions.5 6
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
Three groups of cynomolgus monkeys were studied. Five monkeys
were fed commercial laboratory diet (Purina monkey chow, Ralston
Purina; normal group). Five monkeys were fed an atherogenic diet
containing cholesterol (1 mg/calorie) and fat (43% total
calories) for 23±1.9 months (mean±SEM; atherosclerotic group). Five
monkeys were fed an atherogenic diet for 27±3.6 months followed by
commercial laboratory diet for 14±2.8 months (regression
group).
Sections 3 µm thick were cut and mounted on microscope
slides, dried in room air for at least 4 hours, deparaffinized
(Americlear, Baxter), and rehydrated in ethyl alcohol. Slides were
incubated in PBS, pH 7.0, washed with PBS, and covered with 5% normal
goat serum (Vector Laboratories) and 0.05% Triton X-100 for 60 minutes
to block nonspecific protein binding sites.
Staining of macrophages and SMCs was performed by the
horseradish peroxidase method, by a modified method of Gown et
al.15 Briefly, sections were deparaffinized and
incubated in PBS and 0.25% trypsin for 15 minutes at 37°C. Sections
were rinsed, quenched (0.6% hydrogen peroxide and methanol for 30
minutes), rinsed, boiled in citrate buffer for 5 minutes, allowed to
cool, and again rinsed in PBS. Normal goat serum (5%) was used as a
blocking agent for 30 minutes at 37°C. Sections were immediately
incubated with monoclonal mouse anti–human macrophage antibody
(HAM-56, Dako; diluted 1:50 for 30 minutes at 37°C) or monoclonal
mouse anti–human muscle actin antibody (HHF-35, Dako; diluted 1:50 for
60 minutes at 37°C). Sections were rinsed of excess antibody and
conjugated to biotinylated anti-mouse immunoglobulin (Biogenex) for 20
minutes. Sections were again rinsed and incubated with
peroxidase-conjugated streptavidin for 20 minutes. Staining was
developed by 3,3'-diaminobenzidine (Vector Laboratories). Trypsin
incubation and antigen retrieval were not used in sections that were
stained with HHF-35. Sections stained with HAM-56 were counterstained
with nuclear fast red. Sections stained with HHF-35 were not
counterstained. For both stains, the primary antibody was excluded from
1% normal goat serum as a negative control. Each section was viewed
under a light microscope and photographed.
Results
Top
Abstract
Introduction
Methods
Results
Discussion
References
Plasma Lipids
Plasma total cholesterol concentration was 123±13
mg/dL (mean±SEM) in normal monkeys and 648±41 mg/dL in
atherosclerotic monkeys. Plasma cholesterol in regression
monkeys was 682±62 mg/dL when they received the atherogenic diet and
121±4.6 mg/dL after they were returned to the normal diet.
In aorta and coronary arteries from normal monkeys, there
was faint, diffuse staining in the media of each vessel, with darker
staining in the adventitia (Figure 1A
).
Cell-associated anti–Ang II staining was very sparse and restricted to
a few cells of the endothelium and adventitia (Figure 1A).
View larger version (88K):
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Figure 1. Immunohistochemical staining of monkey aorta
for angiotensin II (Ang II) with Peninsula antiserum and
counterstained with nuclear fast red. A, Normal monkey. There is
diffuse, faint staining in adventitia and minimal staining in
endothelium (magnification x130). B, Atherosclerotic
monkey. There is dark cell-associated staining in intima-media and
diffuse extracellular staining in intima-media and adventitia
(magnification x85). C, Regression monkey. There is faint diffuse
staining in intima-media and adventitia (magnification x85). 
). Areas with cell-associated
staining had an intense blue color, in contrast to extracellular
staining, which was a diffuse, light blue. Similar anti–Ang II
staining was noted in adjacent sections stained with the Peninsula,
Denise (Figure 2), and RAB 82 antisera.
Anti–Ang II staining in monkeys was similar in coronary
arteries and aortas. Normal rabbit serum was used as a negative control
and produced no anti–Ang II immunostaining.
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[in a new window]
Figure 2. Immunohistochemical staining for Ang II in
atherosclerotic monkey aorta with "Denise" antiserum and
counterstained with nuclear fast red. There is minimal staining of
endothelial cells for Ang II. Dark, cell-associated
staining in intima-media is characteristic of atherosclerotic monkey
aorta and is similar to anti–Ang II staining obtained with Peninsula
antiserum in Figures 1B and 3A. Magnification x340.).
To determine the cellular localization of Ang II, adjacent serial
sections were stained for the presence of Ang II, macrophages
(with HAM-56), and SMCs (with HHF-35). Normal blood vessels did not
stain for macrophages in the endothelium or
media, but staining of macrophages was occasionally observed in
the adventitia. In normal vessels, no correlation was detected between
the diffuse anti–Ang II stain and macrophages or SMCs. ) that appeared, with HAM-56,
to be macrophages (Figure 3B). Discrete areas stained very
strongly with both Ang II antibody and HAM-56, suggesting clusters of
macrophages. The media and intima-media stained for SMCs with
HHF-35 (Figure 3C). Staining of cell-associated Ang II in
atherosclerotic lesions was not associated with anti–smooth muscle
cell staining (Figure 3).
View larger version (79K):
[in a new window]
Figure 3. Immunohistochemical staining in serial sections of
atherosclerotic monkey aorta. A, Angiotensin II (Ang II)
with Peninsula antiserum. B, Macrophages with HAM-56. C, Smooth
muscle cells with HHF-35. Magnification x217. Anti–Ang II staining is
observed in intima-media and adventitia. Anti–Ang II staining in
intima-media appears to be associated with macrophages and not
associated with smooth muscle cells.
Anti–Ang II staining was observed in all vessels and appeared to
be both cell-associated and extracellular (Figure 4A). There was positive staining for
macrophages (Figure 4B) and SMCs (Figure 4C). Because tissue
samples were small and orientation was difficult, reliable assessment
of correlation between Ang II and a specific cell type was not
possible.
View larger version (96K):
[in a new window]
Figure 4. Immunohistochemical staining in serial sections of
atherosclerotic human coronary artery. A,
Angiotensin II (Ang II) with Peninsula antiserum. B,
Macrophages with HAM-56. C, Smooth muscle cells with HHF-35.
Magnification x425. Blue anti–Ang II staining appeared to be both
associated with cells and extracellular. In some cells (arrows), blue
stain appeared to be perinuclear. It was not possible to determine
whether anti–Ang II staining was associated with macrophages
or smooth muscle cells.
There were minimal macrophages in normal vessels.
Atherosclerotic aortas and coronary arteries contained a total
of 157±10 and 132±9 cells per high-power field, respectively (both
P<0.05 versus normal vessels). Aortas and coronary
arteries from regression monkeys contained a total of 83±7 and 73±6
cells per high-power field, respectively (aortas, P>0.05
versus normal vessels; coronary arteries, P<0.05
versus normal vessels; both P<0.05 versus atherosclerotic
vessels). ). There were a large number of
Ang II–containing cells in intima-media of aortas and coronary
arteries of atherosclerotic monkeys (54±3% of total cells; both
P<0.05 versus normal vessels) (Figure 5). After regression
of atherosclerosis, the number of Ang II–containing
cells decreased significantly in intima-media of aortas and
coronary arteries (both P<0.05 versus normal and
atherosclerotic vessels) (Figure 5).
View larger version (12K):
[in a new window]
Figure 5. Angiotensin II–containing cells in
intima-media of monkey vessels and human atherosclerotic lesions.
Monkey aortas, coronary arteries, and human coronary
arteries were stained for angiotensin II with Peninsula
antiserum. Values are mean±SEM from 5 normal (N), 5 atherosclerotic
(AS), and 5 regression (R) monkeys and 5 human coronary
atherectomy samples. *P<0.05 vs N,
P<0.05 vs AS.).
Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
The major finding of the present study is that the
intima-media of atherosclerotic blood vessels of monkeys and humans
contains substantial amounts of Ang II, mainly colocalized with
macrophages in atherosclerotic vessels from monkeys. During
regression of atherosclerosis in monkeys,
cell-associated Ang II and macrophages decreased in the
intima-media.
Macrophage-associated staining for Ang II was widely
distributed throughout the intima-media of atherosclerotic blood
vessels in monkeys. Extracellular anti–Ang II stain, which was less
intense than the cell-associated stain, was observed in the adventitia
and media of each group.
There was less Ang II in vessels after regression of
atherosclerosis than in atherosclerotic vessels.
Cell-associated staining for Ang II decreased significantly after
regression, although diffuse extracellular staining was still observed
in the intima-media. The finding that there are fewer
macrophages in the intima-media after regression of
atherosclerosis9 was confirmed in
the present study. The marked decrease in macrophages after
regression of atherosclerosis parallels the decrease of
Ang II–containing cells in intima-media after regression of
atherosclerosis.
Because Ang II is a small, diffusible peptide, it is likely that
Ang II leaked out of cells during fixation, accounting for the diffuse
staining. Because this artifact may contribute to diffuse Ang II
staining, cell-associated localization of Ang II was more convincing
than diffuse staining, especially because Ang II in intima-media
appeared to colocalize with macrophages in monkeys. The dark
blue staining with 3 different antisera was similar to staining of
juxtaglomerular cells of monkey kidney (positive
controls).11 12 Cell-associated localization of
Ang II was similar with 3 different antisera and was prevented by
solid-phase preabsorption. Both findings strongly suggest that the dark
blue staining was specific for Ang II. We also noted perinuclear
anti–Ang II staining in some samples (eg, Figure 4A), which has been
reported in cardiac myocytes and
fibroblasts.24
Ang II has been identified in circulating human mononuclear
leukocytes,4 macrophages in granulomas in
mice,19 and now in macrophages in
atherosclerotic lesions. Vascular proliferation and remodeling are
major events in formation of atherosclerotic
lesions.1 Because Ang II appears to be important
in modulation of proliferation of vascular SMCs and production
of extracellular matrix,26 27 28 we speculate that
Ang II in macrophages may play an important role during
vascular proliferation and remodeling in
atherosclerosis.
Acknowledgments
This work was supported by NIH grants HL-14388, HL-16066,
NS-24621, and AG-10269 and research funds from the Veterans
Association. Dr Sobey was supported by a C.J. Martin Fellowship from
the National Health and Medical Research Council of Australia and was
the recipient of a Michael J. Brody Fellowship in Basic
Cardiovascular Research from the University of Iowa. We
thank Dr Kristy D. Lake for her statistical assistance, Dr Yi Chu for
performing the conjugation and preabsorption experiments, and Arlinda
LaRose for secretarial assistance.
References
Top
Abstract
Introduction
Methods
Results
Discussion
References
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A. Prasad and A. A. Quyyumi Renin-Angiotensin System and Angiotensin Receptor Blockers in the Metabolic Syndrome Circulation, September 14, 2004; 110(11): 1507 - 1512. [Full Text] [PDF]
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 A. Karagiannis, K. Balaska, K. Tziomalos, T. Gerasimidis, D. Karamanos, A. Papayeoryiou, and C. Zamboulis Lack of an association between angiotensin converting enzyme gene polymorphism and peripheral arterial occlusive disease Vascular Medicine, August 1, 2004; 9(3): 189 - 192. [Abstract] [PDF]
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 J. Galle, A. Mameghani, S.-S. Bolz, S. Gambaryan, M. Gorg, T. Quaschning, U. Raff, H. Barth, S. Seibold, C. Wanner, et al. Oxidized LDL and its Compound Lysophosphatidylcholine Potentiate AngII-Induced Vasoconstriction by Stimulation of RhoA J. Am. Soc. Nephrol., June 1, 2003; 14(6): 1471 - 1479. [Abstract] [Full Text] [PDF]
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C. Yan, D. Kim, T. Aizawa, and B. C. Berk Functional Interplay Between Angiotensin II and Nitric Oxide: Cyclic GMP as a Key Mediator Arterioscler. Thromb. Vasc. Biol., January 1, 2003; 23(1): 26 - 36. [Abstract] [Full Text] [PDF]
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 B. Schieffer Interaction of interleukin-6 and angiotensin II in atherosclerosis: culprit for inflammation? Eur. Heart J. Suppl., January 1, 2003; 5(suppl_A): A25 - A30. [Abstract] [PDF]
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M. Ishibashi, K. Egashira, K.-i. Hiasa, S. Inoue, W. Ni, Q. Zhao, M. Usui, S. Kitamoto, T. Ichiki, and A. Takeshita Antiinflammatory and Antiarteriosclerotic Effects of Pioglitazone Hypertension, November 1, 2002; 40(5): 687 - 693. [Abstract] [Full Text] [PDF]
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K. D. O'Brien, D. M. Shavelle, M. T. Caulfield, T. O. McDonald, K. Olin-Lewis, C. M. Otto, and J. L. Probstfield Association of Angiotensin-Converting Enzyme With Low-Density Lipoprotein in Aortic Valvular Lesions and in Human Plasma Circulation, October 22, 2002; 106(17): 2224 - 2230. [Abstract] [Full Text] [PDF]
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R. Candido, K. A. Jandeleit-Dahm, Z. Cao, S. P. Nesteroff;, W. C. Burns, S. M. Twigg, R. J. Dilley, M. E. Cooper, and T. J. Allen Prevention of Accelerated Atherosclerosis by Angiotensin-Converting Enzyme Inhibition in Diabetic Apolipoprotein E-Deficient Mice Circulation, July 9, 2002; 106(2): 246 - 253. [Abstract] [Full Text] [PDF]
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 E. Suzuki, H. Nishimatsu, H. Satonaka, K. Walsh, A. Goto, M. Omata, T. Fujita, R. Nagai, and Y. Hirata Angiotensin II Induces Myocyte Enhancer Factor 2- and Calcineurin/Nuclear Factor of Activated T Cell-Dependent Transcriptional Activation in Vascular Myocytes Circ. Res., May 17, 2002; 90(9): 1004 - 1011. [Abstract] [Full Text] [PDF]
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C. A. Hathaway, D. D. Heistad, D. J. Piegors, and F. J. Miller Jr Regression of Atherosclerosis in Monkeys Reduces Vascular Superoxide Levels Circ. Res., February 22, 2002; 90(3): 277 - 283. [Abstract] [Full Text] [PDF]
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A. Prasad, J. P. J. Halcox, M. A. Waclawiw, and A. A. Quyyumi Angiotensin type 1 receptor antagonism reverses abnormal coronary vasomotion in atherosclerosis J. Am. Coll. Cardiol., October 1, 2001; 38(4): 1089 - 1095. [Abstract] [Full Text] [PDF]
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S. Keidar, R. Heinrich, M. Kaplan, T. Hayek, and M. Aviram Angiotensin II Administration to Atherosclerotic Mice Increases Macrophage Uptake of Oxidized LDL: A Possible Role for Interleukin-6 Arterioscler. Thromb. Vasc. Biol., September 1, 2001; 21(9): 1464 - 1469. [Abstract] [Full Text] [PDF]
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A. Prasad, T. Tupas-Habib, W. H. Schenke, R. Mincemoyer, J. A. Panza, M. A. Waclawin, S. Ellahham, and A. A. Quyyumi Acute and Chronic Angiotensin-1 Receptor Antagonism Reverses Endothelial Dysfunction in Atherosclerosis Circulation, May 23, 2000; 101(20): 2349 - 2354. [Abstract] [Full Text] [PDF]
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