© 1999 American Heart Association, Inc.
Original Contributions |
Induction of Monocyte Binding to Endothelial Cells by MM-LDL
Role of Lipoxygenase Metabolites
Presented in part as an abstract at the Joint Annual Meeting of the American Society for Biochemistry, the American Society for Investigative Pathology, and the American Association of Immunologists, New Orleans, La, 1996.
From the Department of Medicine (Cardiology) (H.M.H., J.I.G., J.N.W., J.A.B.), Physiology (J.N.W.), and Pathology and Laboratory Medicine (N.L., M.F., J.A.B.), Cardiovascular Research Laboratory (H.M.H., J.I.G., J.N.W.), University of California at Los Angeles; and City of Hope National Medical Center (R.N., J.L.N.), Duarte, Calif.
Correspondence to Henry M. Honda, MD, UCLA School of Medicine, CHS 47-123, 10833 Le Conte Ave, Los Angeles, CA 90095-1679. E-mail hhonda{at}mednet.ucla.edu
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Abstract |
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Abstract—Treatment of human aortic endothelial cells (EC) with minimally oxidized LDL (or minimally modified LDL, MM-LDL) produces a specific pattern of endothelial cell activation distinct from that produced by LPS, tumor necrosis factor-
, and interleukin-1, but similar to
other agents that elevate cAMP. The current studies focus on the signal
transduction pathways by which MM-LDL activates EC to bind
monocytes. We now demonstrate that, in addition to an elevation of
cAMP, lipoxygenase products are necessary for the
MM-LDL response. Treatment of EC with inhibitors of the
lipoxygenase pathway, 5,8,11,14-eicosatetraynoic acid
(ETYA) or cinnamyl-3,4-dihydroxy--cyanocinnamate (CDC), blocked
monocyte binding in MM-LDL-treated EC (MM-LDL=118±13%;
MM-LDL+ETYA=33±4%; MM-LDL+CDC=23±4% increase in monocyte binding)
without reducing cAMP levels. To further investigate the role of the
lipoxygenase pathway, cellular phospholipids were
labeled with arachidonic acid. Treatment of cells for 4
hours with 50 to 100 µg/mL MM-LDL, but not native LDL, caused a 60%
increase in arachidonate release into the medium and
increased the intracellular formation of 12(S)-HETE (
100%
increase). There was little 15(S)-HETE present, and no increase in
its levels was observed. We demonstrated that 12(S)-HETE reversed the
inhibitory effect of CDC. We also observed a 70% increase
in the formation of 11,12-epoxyeicosatrienoic acid (11,12-EET) in cells
treated with MM-LDL. To determine the mechanism of
arachidonate release induced by MM-LDL, we examined the
effects of MM-LDL on intracellular calcium levels. Treatment of EC with
both native LDL and MM-LDL caused a rapid release of intracellular
calcium from internal stores. However, several pieces of evidence
suggest that calcium release alone does not explain the increased
arachidonate release in MM-LDL-treated cells. The
present studies suggest that products of
12-lipoxygenase play an important role in MM-LDL action
on the induction of monocyte binding to EC.
Key Words: intracellular calcium • lipoxygenase inhibitors • minimally modified LDL • endothelial cells
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Introduction |
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Previous studies by our group have demonstrated that minimally modified LDL (MM-LDL) produces a distinct pattern of endothelial cell (EC) activation.1 2 3 Exposure of EC to the major cytokines, tumor necrosis factor-
(TNF-) and interleukin-1 (IL-1), and
lipopolysaccharide (LPS) increased transcription of
intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion
molecule-1 (VCAM-1), and E-selectin, adhesion molecules that promote
both neutrophil and monocyte binding.4 5 In contrast,
MM-LDL selectively stimulates EC to bind monocytes but not
neutrophils2 by an alternatively spliced variant of
fibronectin6 and without increasing expression levels of
ICAM-1, VCAM-1, or E-selectin.3 We have previously
demonstrated that treatment of EC with MM-LDL caused a rapid increase
in cAMP that was necessary for the induction of monocyte binding by
MM-LDL.1 We also found that other agents that increase
cAMP, including cholera toxin, pertussis toxin, and dibutyryl cAMP, had
a similar effect to MM-LDL; these agents stimulated monocyte but not
neutrophil binding to EC without increasing expression of ICAM-1,
VCAM-1, and E-selectin.1 Taken together these observations
suggest that MM-LDL and cytokines activate distinct
signal transduction pathways. These separate pathways may determine the
differences between acute inflammation mediated by neutrophils and
chronic inflammation mediated by monocytes. To elucidate the signal transduction mechanisms by which MM-LDL activates the endothelium, we have examined the role of lipoxygenase (LO) metabolites in the actions of MM-LDL. The LO pathway was investigated because several previous studies had suggested that responses to oxidation were mediated by this pathway.7 8
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Methods |
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Cell Preparation
Human aortic EC (HAEC) were isolated from aortic specimens and cultured as previously described.9 Human monocytes were isolated by the modified Recalde method as described previously.10
Intracellular Calcium Measurements
Intracellular calcium (Cai) measurements
were performed as previously described.11 In brief, HAEC
were grown to confluence on glass coverslips coated with Cell-Tak
(Becton Dickinson) and 3 µg/mL of a collagen derivative (Vitrogen;
Celtrix). Before the experiments, HAEC were incubated for 30 minutes in
2 µmol/L Fura-2 AM (Molecular Probes) in serum-free Hanks
buffered salt solution (HBSS) at 37°C. The cells were then washed in
Fura-free HBSS and kept in the dark at room temperature for 30 minutes
before the start of the experiment to allow for deesterification of the
fluorescent dye. The video image was digitized using the Axon
Imaging Workbench 2 (Axon Instruments, Inc). A 5x5 pixel area of an EC
was processed by dividing each even field by its corresponding odd
field to produce a ratiometric measure of relative
Cai concentration. Each point represents
the average of 4 to 10 consecutive frames (obtained at video speed of
30/s) of the fluorescence ratio. Background
fluorescence represented less than 5% of the total
fluorescence at 335 and 405 nm and was not subtracted from each
image before calculation of the fluorescence ratio.
Quantitation of Arachidonic Acid
Metabolites
For analysis of labeled phospholipids HAEC were
incubated in M199 and 10% FCS with 5 µCi/mL
3H-arachidonate for 24 hours. To
remove extracellular free arachidonate, HAEC were rinsed 3
times and incubated with 0.05% BSA in M199 for 2 hours and
subsequently in M199 and 10% FCS for 2 hours. This method has been
previously used for labeling phospholipids in porcine aortic
EC.12 The medium was tested to ensure that essentially all
the free arachidonate had been washed away. The cells that
had been labeled with arachidonate and washed were then
placed in fresh medium with or without 100 µg/mL of native LDL or
MM-LDL for 4 hours. Lipids were extracted from medium and cells before
and after this 4-hour incubation using chloroform
methanol.13 After that time medium and cells were
collected. To determine the distribution of labeled
arachidonate, the chloroform and methanol were removed by
drying under a stream of nitrogen, and chloroform was added to
resuspend the lipids. These were applied to an aminopropyl column;
neutral lipids, phospholipids, and fatty acids were collected
separately as described previously.14 For analysis
of arachidonate metabolites, lipid extracts from medium and
cells were collected and processed as previously
described.12 15 In brief, lipids from the medium were
prepared by chloroform methanol extraction. Lipid extracts from media
were dried, resuspended, and placed onto a solid-phase C18 column. The
column was washed with water, and arachidonate and its
metabolites were collected in ethyl acetate; thus only free fatty acids
were analyzed. In initial studies, lipid extract from cells was
processed in the same manner but no lipid was detected in the free
fatty acid fractions. Thus for further studies lipid extracts from
cells were hydrolyzed with 0.2N methanolic NaOH in the dark under
N2 and in the presence of the antioxidant propyl
gallate to prevent nonspecific oxidation. The hydrolyzed lipids were
then collected and placed onto the C18 solid-phase column and processed
as described for the medium. Reverse-phase high-performance
liquid chromatography (HPLC) was performed as
previously described.16 Samples were placed onto a C18
column (Bio-Sil HL 90-5S 250x4.6 mm) and eluted using a series of
isocratic solutions of 0.1% trifluoroacetic acid (TFA), water, and
acetonitrile. One-minute fractions were collected and radioactivity
determined. The column elution profile was determined using standards
of 12S-hydroxyeicosatetraenoic acid
(12S-HETE), 15-HETE, 11,12-epoxyeicosatrienoic acid (11,12-EET), and
6-keto-PGF1 (Biomol Research Laboratories).
The order of elution of the standard was similar to that shown
previously.16 Recoveries from the reverse-phase column
were calculated to be approximately 80%.
In separate studies arachidonate metabolites were measured
by radioimmunoassay (RIA). These assays for 12-HETE and
6-keto-PGF1 were performed as previously
described.12 15
Preparation of LDL and MM-LDL
LDL was isolated by density-gradient
centrifugation. To avoid oxidation of native LDL, blood
was drawn into sodium citrate and all solutions were supplemented with
0.01% EDTA. Thioburbituric acid reactive substances (TBARS)
levels were less than 1 nmol · L-1
· mg-1 LDL protein. MM-LDL was prepared by
iron oxidation as described previously.17 TBARS levels
were 2 to 3 nmol · L-1 ·
mg-1 protein and beta carotene was decreased by
90%. Both native LDL and MM-LDL were stored with 80 µmol/L BHT
and 0.01% EDTA. The exact concentration of MM-LDL to which EC are
exposed in the subintimal space within the vessel wall in vivo is not
known; however, if the serum concentration of LDL is 150 mg/dL, then
100 µg/mL represents 7% of the serum levels of LDL. It is
possible that MM-LDL is concentrated or "trapped" within the
subintimal space as suggested by electron microscopic images of the
vessel wall in atherosclerotic lesions.18 Because all
preparations of MM-LDL stimulated monocyte binding at 100 µg/mL, we
have included this concentration of MM-LDL in all of our studies.
Monocyte Adhesion Assay
These assays were performed essentially as described
previously.1 HAEC in M199 containing 10% FBS were grown
to confluency in 48-well dishes and exposed to LDL or MM-LDL for 4
hours at 37°C. For certain experiments, EC were pretreated with LO or
cyclooxygenase inhibitors
(cinnamyl-3,4-dihydroxy--cyanocinnamate [CDC],
5,8,11,14-eicosatetraynoic acid [ETYA], or
indomethacin; Biomol) for 30 minutes before addition of
LDL or MM-LDL. In other experiments, EC in M199 with 5% FBS were
treated with 12(S)-HETE or arachidonic acid (Biomol).
After incubation HAEC were rinsed, and monocytes were added to the
wells for 12 minutes. Unbound monocytes were removed by rinsing and the
number of bound monocytes was determined. Counting was done at a
magnification of 50x using an eyepiece grid. For each test
sample, 4 wells were used and 3 fields per well were counted. Control
wells contained approximately 30 to 40 monocytes per high-power field.
Three separate experiments were performed for each condition
tested.
cAMP Measurements
cAMP measurements were performed as described previously by our
group using the cAMP RIA kit (Amersham Corp).1
Statistical Analysis
Data are presented as mean±SE and analyzed
using the Student's t test. Differences were considered
significant at P<0.05.
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Results |
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Lipoxygenase Inhibitors but not a Cyclooxygenase Inhibitor Block the Induction of Monocyte Binding to Endothelial Cells by MM-LDL
EC were treated for 30 minutes with the LO inhibitors, CDC (10-8 mol/L) or ETYA (10-8 mol/L), or the cyclooxygenase inhibitor indomethacin (10-8 mol/L). LDL or MM-LDL (100 µg/mL) in M199 containing 10% FBS was then added for 4 hours. After treatment, wells were washed and the monocyte adhesion assay was performed. MM-LDL but not LDL at 100 µg/mL increased the number of monocytes bound to the monolayer by 118±13% (Figure 1
, top). MM-LDL at 50 µg/mL but not 20
µg/mL also caused a significant increase in monocyte binding (47±5%
increase at 50 µg/mL, 5±4% increase at 20 µg/mL). Pretreatment
with ETYA or CDC significantly blunted this increase in monocyte
binding in response to MM-LDL to 33±4% and 23±4%, respectively,
whereas indomethacin had no effect (118±5%). There
was no effect of the inhibitors alone on monocyte binding
to untreated cells (data not shown). The inhibitory effect
of CDC on MM-LDL induction of monocyte binding could be completely
reversed by the addition of 10-8 mol/L
12(S)-HETE, a major arachidonate metabolite of LO in EC
treated by MM-LDL (Figure 1, bottom).
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Lipoxygenase Inhibitors do not Block
the cAMP Increase Induced by MM-LDL
We have previously shown that MM-LDL but not LDL treatment
of EC causes a rapid increase in levels of cAMP.1 This
increase was necessary for the effects of MM-LDL on monocyte binding
because inhibition of protein kinase A by
N-(2-[Methylamino]ethyl)-5-isoquinoline-sulfonamide prevented
the induction of monocyte binding by MM-LDL.1 To determine
whether the effects of CDC and EYTA were mediated by a change in the
levels of cAMP in MM-LDL-treated cells, EC monolayers were treated for
1 hour with MM-LDL in the presence of the phosphodiesterase
inhibitor 3-isobutyl-1-methylxanthine (IBMX). We
have previously shown that 1 hour represents the time of the
maximal cAMP response induced by MM-LDL.1 One hour of
MM-LDL but not LDL treatment caused a 115±5% increase in cAMP (Figure 2). EC pretreated with CDC actually
exhibited higher levels of cAMP after MM-LDL treatment (194±5%
increase) whereas EC pretreated with ETYA had a similar increase to
that seen with MM-LDL alone. The inhibitors did not affect
the levels of cAMP in untreated cells (data not shown). Therefore LO
inhibitors, which prevented the induction of monocyte
binding by MM-LDL, did not prevent the MM-LDL-induced increase in
cAMP.
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MM-LDL Increases the Metabolism of
Arachidonic Acid and the Production of
Lipoxygenase Products by Endothelial Cells
To determine the effect of MM-LDL on arachidonate
metabolism, EC were labeled for 24 hours with
3H-arachidonic acid. The cells
were then extensively rinsed and incubated for 1 hour in medium
containing BSA to remove free arachidonic acid. After
these rinses, less than 1% of the
3H-arachidonate remained as the free
fatty acid, 2.5% was incorporated into triglycerides, and
approximately 96% was incorporated into phospholipid. These labeled
cells were incubated for 4 hours with or without 100 µg/mL of native
LDL or MM-LDL. Arachidonate and arachidonate
metabolites were released into the medium as demonstrated by HPLC
(Figure 3, top). The major metabolites
were 12-HETE and a mode correlating with 11,12-EET (referred to as
11,12-EET). There were lesser amounts of 15-HETE and an unknown, highly
lipophilic metabolite. Very little prostaglandin (which
elutes in fractions earlier than the HETE or EET) was released from
these cells. MM-LDL treatment of EC for 4 hours increased
arachidonate release and also significantly increased
levels of 11,12-EET, the unknown metabolite, and, to a smaller extent,
12S-HETE in the medium (Figure 4, top).
The profiles and levels of cell-associated arachidonate
metabolites were also examined after the 4-hour incubation period. In
contrast to the medium, less than 4% of labeled cell-associated
arachidonate was unesterified; thus cellular lipids were
analyzed after hydrolysis. As demonstrated by HPLC, the major
peak of cell-associated arachidonate metabolites contained
12-HETE (Figure 3, bottom). Lower amounts of 11,12-EET were also
present. Label was also found in 2 unidentified nonpolar peaks. The
amounts of 12-HETE as well as 11,12-EET were significantly increased in
cells treated with MM-LDL but not with native LDL (Figure 4, bottom). In a separate set of experiments using RIA, we observed that
12-HETE synthesis and release were increased in HAEC treated as above
with MM-LDL but not LDL (Table). Greater
increases were seen in this RIA compared with the labeling studies,
probably because of variability in EC from different donors. Treatment
of EC with concentrations of CDC and ETYA, which blocked induction of
monocyte binding by MM-LDL, also inhibited MM-LDL-induced 12-HETE
formation as measured by HPLC (CDC, -78±6%; ETYA, -81±5% compared
with cells not exposed to CDC or ETYA). Levels of 11,12-EET were
unaffected by CDC or ETYA (data not shown).
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P<0.08 vs
control.
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MM-LDL Increases Endothelial Intracellular
Calcium Levels
One established mechanism by which arachidonate
metabolism is stimulated is through increases in
Cai and stimulation of cytosolic phospholipase
A2 (cPLA2).19
We therefore tested the effects of MM-LDL on EC
Cai. As seen in Figure 5, 100 µg/mL of MM-LDL led to a rapid
increase in EC Cai. To determine whether this
increase in EC Cai, was mediated by release from
intracellular stores or influx from the extracellular space, we tested
the effect of 100 µg/mL of MM-LDL on EC Cai in
the presence and absence of extracellular 5 mmol/L EGTA (Figure 6). MM-LDL increased EC
Cai to a similar magnitude in both conditions,
demonstrating that MM-LDL increases EC Cai
primarily by releasing calcium from intracellular stores. Because LDL
also had been shown to increase Cai in bovine
aortic EC,20 but did not lead to significant increases in
monocyte binding1 or levels of 12-HETE in human aortic EC
(Table
), we compared the effects of various concentrations of
LDL and MM-LDL on EC Cai (Figure 7). Both MM-LDL and native LDL increased
Cai at 1, 5, 10, and 100 µg/mL in a
concentration-dependent manner. MM-LDL led to a small but significantly
greater increase in EC Cai compared with LDL
(P<0.05 at each concentration tested, n=3). We also found
that a lower dose of MM-LDL (50 µg/mL), which gave an equivalent
increase in EC Cai as did 100 µg/mL of LDL,
induced monocyte binding whereas LDL had no effect on monocyte binding
(data not shown).
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Discussion |
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The present studies have addressed several aspects of the MM-LDL signal transduction pathway in HAEC. We have previously shown that inhibitors of protein kinase A block MM-LDL induction of monocyte binding to EC, indicating the importance of the cAMP pathway.1 We now present evidence that the LO pathway is also necessary for the MM-LDL signal transduction pathway leading to increased monocyte binding. Pretreatment of EC with LO but not cyclooxygenase inhibitors blocked MM-LDL induction of monocyte binding without inhibiting the increase in cAMP elevation (Figure 2
). The LO inhibitors used in
this study, EYTA and CDC, both have been shown to be relatively
specific at the concentrations used in this study. CDC most potently
inhibits 12-LO with lesser effects on 5-LO and 15-LO, and without
effects on cyclooxygenase or cytochrome
P450.21 At higher concentrations than used in these
experiments, EYTA can inhibit both 5-LO at 10-8
mol/L, cytochrome P450 at 10-7 mol/L, and
cyclooxygenase at 10-6
mol/L.22 In our studies we have demonstrated an
approximately 80% inhibition of 12-HETE production by CDC and
ETYA. Thus we conclude that the LO inhibitors at the
concentrations used in these experiments specifically blocked 12-LO
activity.
To gain more insight into role of the LO pathway in MM-LDL induction of
monocyte binding, we labeled EC with
3H-arachidonate and examined
arachidonate release and production of
oxygenated derivatives of arachidonate in
untreated and MM-LDL-treated EC. Arachidonic acid is
the precursor for several eicosanoids with potent biological effects
including inflammation and cell growth.23 The major
oxidative products released into the medium under unstimulated
conditions were 11,12-EET (a product of the cytochrome P450
pathway) and 12-HETE (Figure 3, top); lower levels of 15-HETE
and 6-keto-PGF1 were also released into the
medium. The low level of prostaglandin release most likely
relates to the fact that these cells were used at passage 8 as others
have shown a steady loss of cyclooxygenase
products in passaged EC.24 In the cytoplasm most of
the oxidized product within the cells was 12-HETE with lower levels
of 11,12-EET. It should be noted that although the product
identified as 11,12-EET migrates with authentic 11,12-EET in our HPLC
system, it has not been chemically identified as 11,12-EET. Except for
the lack of prostaglandins, the arachidonate
metabolites released were similar to those found in bovine
coronary EC.25
Treatment of EC with MM-LDL caused a 60% increase in the release of
arachidonate into the medium. This was associated with a
significant increase in cell-associated 12-HETE and, to a lesser
extent, medium content of 12-HETE (Figure 4, top and bottom,
Table). In a previous publication, we demonstrated that EC
contain 12-LO but not 15-LO,26 the major product of
which is 12-HETE. These studies demonstrate that 12-HETE can reverse
the effect of CDC on MM-LDL-induced monocyte binding (Figure 1, bottom). Because 12-HETE is elevated in MM-LDL-treated cells and can
mimic the effect of MM-LDL on monocyte binding,27
it is likely to be an important mediator of MM-LDL activity.
Recent studies have demonstrated that the metabolites of linoleic acid,
9-hydroxyoctadeca-10,12-dienoic acid and
13-hydroxyoctadeca-9,11-dienoic acid in oxidized lipids, can
activate the nuclear hormone receptor transcription factor
PPAR
in macrophages.28 Although PPAR is
expressed in high levels in adipose tissues as well as in
macrophage foam cells, there appeared to be little if any
expression in EC within an atherosclerotic lesion when
macrophage foam cells are present.28 Further
studies, however, are required to determine whether metabolites of
linoleic acid can mediate some of the biological effects of MM-LDL.
In addition to the increase in 12-HETE in EC in response to MM-LDL, we also observed a significant increase in 11,12-EET induced by treatment of EC with MM-LDL. EETs have been shown to be formed by metabolism of arachidonate by the cytochrome P450 pathway and not by LO.29 Increased levels of 11,12-EET have been previously observed in EC treated with high concentrations of native LDL for 4 days.30 In addition, previous studies have shown that 11,12-EET can stimulate monocyte–endothelial interactions in human umbilical vein EC.31 This agent has been shown to cause vascular relaxation30 and thus might be an important mediator of vascular tone in atherosclerosis, in which endothelial-derived nitric oxide levels are reduced.
Treatment of EC with MM-LDL, and to a lesser extent native LDL,
released calcium from internal stores (Figure 6). Although an
increase in Cai by itself may cause activation of
cPLA2 and thereby contribute to
arachidonate release and consequent stimulation of LO
activity,19 32 the present studies suggest that
mechanisms in addition to increases in EC Cai are
required for arachidonate release and generation of LO
products by MM-LDL. This finding is supported by the finding that
native LDL at a concentration of 100 µg/mL increased EC
Cai to nearly the same extent as 50 or 100
µg/mL MM-LDL but did not increase levels of 12-HETE or monocyte
binding. Several groups33 34 have documented the presence
of calcium-independent PLA2. We conclude that an
increase in Cai is not sufficient for
arachidonate release by MM-LDL.
The present studies suggest that the LO products synthesized in
response to MM-LDL act downstream or parallel to cAMP in the signal
transduction pathway of MM-LDL (Figure 1, top and bottom). We
have previously presented evidence that both cAMP and MM-LDL
increase nuclear factor-kappa B (NF-
B) activation in
HAEC.1 In addition, several genes whose transcription is
increased by MM-LDL have important NF-B elements in the promoter
region.35 36 37 Previous studies have shown that NF-B
activation may involve reactive oxygen intermediates.38
Inhibition of the LO pathway has been shown to decrease NF-B
activation, suggesting that the products of this pathway may be
involved in endothelial activation.8
In summary, the current studies suggest that MM-LDL stimulates formation of oxygenated fatty acids by both the LO and P450 pathways. An increase in Cai is not sufficient for the generation of arachidonate in EC exposed to MM-LDL. Finally, LO metabolites, in particular 12-HETE, appear to mediate the increase of monocyte binding to EC exposed to MM-LDL.
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Acknowledgments |
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Supported by the National Institutes of Health (HL-30568, R01-HL-44880, P01-HL-55798), American Heart Association-Greater Los Angeles Affiliate (CS-1012), the Laubisch Fund, the Juvenile Diabetes Association, and the Chizuko Kawata Endowment. The authors thank Marineh Yagoubian for excellent tissue culture work, and Scott Lamp and John Parker for their participation in the development of the calcium imaging system.
Received March 12, 1998; accepted August 27, 1998.
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References |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1. Parhami F, Fang Z, Fogelman AM, Andalibi A, Territo MC, Berliner JA. MM-LDL induced inflammatory responses in endothelial cells are mediated by cAMP. J Clin Invest. 1993;92:471–478.
2. Berliner JA, Territo MC, Sevanian A, Ramin S, Kim JA, Bamshad B, Esterson M, Fogelman AM. Minimally modified LDL stimulates monocyte-endothelial interactions. J Clin Invest. 1990;85:1260–1266.
3. Kim JA, Territo MC, Wayner E, Carlos TE, Parhami F, Smith CW, Haberland ME, Fogelman AM, Berliner JA. Partial characterization of the leukocyte binding molecule(s) on endothelial cells induced by minimally oxidized LDL. Arterioscler Thromb. 1994;14:458–463.
4. Pober JS, Cotran RS. Cytokines and endothelial cell biology. Pathol Rev. 1990;70:427–451.
5. Fajardo LF. The complexity of endothelial cells. Am J Clin Pathol. 1989;92:241–250.[Medline] [Order article via Infotrieve]
6. Shih PT, Elices MJ, Fang ZT, Ugarova TP, Srahl D, Territo MC, Frank JS, Kovach NL, Cabanas C, Berliner JA, Vora DK. MM-LDL induces monocyte adhesion to endothelial CS-1 by activating beta 1 integrins. J Clin Invest. In press.
7.
Weidtmann A, Sheithe R, Hrboticky N, Pietsch A, Lorenz
R, Siess W. Mildly oxidized LDL induces platelet aggregation
through activation of phospholipase A2. Arterioscler Thromb Vasc
Biol. 1995;15:1131–1138.
8. Pahl HL, Baeuerle PA. Activation of NF-kappa B by ER stress requires both Ca2+ and reactive oxygen intermediates as messengers. FEBS Lett. 1996;392:129–136.[Medline] [Order article via Infotrieve]
9. Navab M, Hough GP, Stevenson LW, Drinkwater DC, Laks H, Fogelman AM. Monocyte migration into the subendothelial space of a coculture of adult human aortic endothelial and smooth muscle cells. J Clin Invest. 1988;82:1853–1863.
10. Fogelman AM, Elahi F, Sykes K. Van Lenten BJ, Territo MC, Berliner JA. A modification of the Recalde method for the isolation of human monocytes. J Lipid Res. 1988;29:1243–1247.[Abstract]
11. Honda HM, Goldhaber JI, Demer LL, Weiss JN. Endothelium-dependent vasodilators do not cause propagated intercellular Ca2+ waves in vascular endothelial monolayers. Cell Calcium. 1996;19:97–104.[Medline] [Order article via Infotrieve]
12. Brown ML, Jakubowki JA, Leventis LL, Deykin K. Elevated glucose alters eicosanoid release from porcine aortic endothelial cells. J Clin Invest. 1988;82:2136–2141.
13. Bligh EG, Dyer WJ. A rapid method of total lipid extraction and purification. Can J Biochem Physiol. 1959;37:911–917.
14. Kaluzny MA, Duncan LA, Merritt MV, Epps DE. Rapid separation of lipid classes in high yield and purity using bonded phase columns. J Lipid Res. 1985;26:135–140.[Abstract]
15.
Natarajan R, Gu J-L, Rossi J, Gonzales N, Lanting L, Xu
L, Nadler J. Elevated glucose and angiotensin II increase
12-lipoxygenase activity and expression in porcine
aortic smooth muscle cells. Proc Natl Acad Sci U S A. 1993;90:4947–4951.
16. Peters SP, Schulman ES, Liu MC, Hayes EC, Lichtenstein LM. Separation of major prostaglandin, leukotrienes, and mono-HETES by high performance liquid chromatography. J Immunol Methods. 1983;64:335–343.[Medline] [Order article via Infotrieve]
17. Liao F, Berliner JA, Mehrabian M, Navab M, Demer L, Lusis AJ, Fogelman AM. MM-LDL is biologically active in vivo in mice. J Clin Invest. 1991;87:2253–2257.
18.
Nivelstein PFEM, Fogelman AM, Mottino G, Frank JS.
Lipid accumulation in rabbit aortic intima 2 hours after bolus infusion
of low density lipoprotein: a deep-etch and immunolocalization study of
ultrarapidly frozen tissue. Arterioscler Thromb. 1991;11:1795–1805.
19.
Channon JY, Leslie CC. A calcium-dependent mechanism
for associating a soluble arachidonoyl-hydrolyzing phospholipase
A2 with membrane in the macrophage cell
line RAW 264.7. J Biol Chem. 1990;265:5409–5413.
20. Haller H, Rieger M, Linschau C, Kuhlmann M, Philipp S, Luft FC. LDL increases [Ca++]i in human endothelial cells and augments thrombin-induced cell signaling. J Lab Clin Med. 1994;124:708–714.[Medline] [Order article via Infotrieve]
21. Cho H, Ueda M, Tamaoka M, Hamaguchi M, Aisaka K, Kiso Y, Inoue T, Ogino R, Tatsuoka T, Ishihara T, Noguchi T, Morita I, Murota S. Novel carreic acid derivatives: extremely potent inhibitors of 12-lipoxygenase. J Med Chem. 1991;34:1503–1505.[Medline] [Order article via Infotrieve]
22. Salari H, Braquet P, Borgeat P. Comparative effects of indomethacin, acetylenic acids, 15-HETES, nordihydroguaiaretic acid and BW755C on the metabolism of arachidonic acid in human leukocytes and platelets. Prostaglandins Leukot Med. 1984;13:53–60.[Medline] [Order article via Infotrieve]
23. DiMarzo V. Arachidonic acid and eicosanoids as targets and effectors in second messenger interactions. Prostaglandins Leukot Essent Fatty Acids. 53:239–254.
24.
Brown ML, Deykin D. Passage state affects
arachidonic acid content and eicosanoid release in
porcine aortic endothelial cells. Arterioscler
Thromb. 1991;11:167–173.
25. Rosolowsky M, Cambell WB. Synthesis of HETE and EETs by cultured bovine coronary artery endothelial cells. Biochim Biophys Acta. 1996;1299:267–277.[Medline] [Order article via Infotrieve]
26.
Kim JA, Gu J, Natarajan R, Berliner JA, Nadler JL. A
leukocyte type of 12-lipoxygenase is expressed in human
vascular and mononuclear cells; evidence for upregulation by
angiotensin II. Arterioscler Thromb Vasc Biol. 1995;15:942–948.
27. Kim MD, Harper CM, Kim JA, Natarajan RD, Nadler JL, Berliner JA, Hedrick CC. 12 Lipoxygenase products increase monocyte binding to human aortic endothelial cells. Circulation. 1997;96(suppl I):I-111.
28.
Tontonoz P, Nagy L, Alvarez JGA, Thomazy VA, Evans RM.
PPAR promotes monocyte/macrophage differentiation and
uptake of oxidized LDL. Cell. 1998;93:241–252.[Medline]
[Order article via Infotrieve]
29.
Campbell WB, Gebremedhin D, Pratt PF, Harder DR.
Identification of epoxyeicosatrienoic acids as
endothelium-derived hyperpolarizing factors. Circ
Res. 1996;78:415–423.
30. Pritchard KA, Wong PY-K, Stemerman MB. Atherogenic concentration of low-density lipoprotein enhance endothelial cell generation of epoxyeicosatrienoic acid products. Am J Pathol. 1990;136:1383–1391.[Abstract]
31. Pritchard KA Jr, Tota RR, Stemerman MB, Wong PY-K. 14,15-Epoxyeicosatrienoic acid promotes endothelial cell dependent adhesion of human monocytic tumor U937 cells. Biochem Biophys Res Comm. 1990;167:137–142.[Medline] [Order article via Infotrieve]
32. Clark JD, Lin L-L, Kriz RW, Ramesha CS, Sultzman LA, Lin AY, Milona N, Knopf JL. A novel arachidonic acid-selective cytosolic PLA2 contains a Ca2+-dependent translocation domain with homology to PKC and GAP. Cell. 1991;65:1043–1051.[Medline] [Order article via Infotrieve]
33. Buckley BJ, Barchowsky A, Dolor RJ, Whorton AR. Regulation of arachidonic acid release in vascular endothelium: Ca2+-dependent and independent pathways. Biochem J. 1991;280:281–287.
34.
Balsinde J, Dennis EA. Function and inhibition of
intracellular calcium-independent phopholipase
A2. J Biol Chem. 1997;272:16069–16072.
35.
Rajavashisth TB, Yamada H, Mishra NK. Transcriptional
activation of the macrophage-colony stimulating factor gene by
minimally modified LDL: involvement of nuclear factor-kappa B.
Arterioscler Thromb Vasc Biol. 1995;15:1591–1598.
36.
Peth P, Parry GC, Mackman N. Regulation of the tissue
factor gene in human monocytic cells. Arterioscler Thromb Vasc
Biol. 1997;17:365–374.
37.
Parry GC, Mackman N. A set of inducible genes expressed
by activated human monocytic and endothelial
cells contain kappa B-like sites that specifically bind c Rel p65
heterodimers. J Biol Chem. 1994;269:20823–20825.
38.
Schreck R, Albermann K, Baeuerle PA. Nuclear Factor
B: an oxidative stress-responsive transcription factor of
eukaryotic cells. Free Radic Res Comm. 1992;17:221–237.[Medline]
[Order article via Infotrieve]
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