Review
Cardiovascular Research (2009) 82, 201–211
doi:10.1093/cvr/cvp070
Sphingosine-1-phosphate as a mediator of high-density
lipoprotein effects in cardiovascular protection
Katherine Sattler and Bodo Levkau*
Institute of Pathophysiology, Zentrum für Innere Medizin, Universitätsklinikum Essen, Hufelandstr. 55, 45122 Essen, Germany
Received 9 December 2008; revised 23 January 2009; accepted 10 February 2009; online publish-ahead-of-print 20 February 2009
Time for primary review: 32 days
KEYWORDS
High-density lipoproteins
(HDL);
Sphingosine-1-phosphate
(S1P);
Cardiovascular protection
Sphingosine-1-phosphate (S1P) has gained special attention in the high-density lipoprotein (HDL) field
because HDL is the most prominent plasma carrier of S1P and because the S1P content of HDL may
be responsible for many of the pleiotropic functions of HDL. This revelation has come from the evidence
that HDL employ S1P receptors and signalling pathways to implement several HDL-ascribed biological
effects as diverse as endothelial nitric oxide production, vasodilation, survival, and cardioprotection.
This review focuses on HDL effects that are completely or partially mediated by the S1P content of
the HDL particle and differentiates them from genuine HDL effects that are S1P-independent. In
addition, the functional properties of ‘free’, HDL-unbound S1P are sometimes different from or even
contrary to those of HDL-associated S1P. The nature of the physical interactions between HDL and
local and systemic S1P production will be discussed as well as their consequences for organ function.
Finally, we will elucidate the potential benefits and limitations of S1P analogues as a new class of
functional HDL mimetics for cardiovascular therapy.
1. Pleiotropic effects of high-density
lipoproteins in cardiovascular protection
Ever since the first descriptions of an association between low
levels of high-density lipoprotein cholesterol (HDL-C) with
coronary artery disease nearly 60 years ago,1,2 the role of
high-density lipoproteins (HDL) as the best endogenous predictor of the development of coronary artery disease and cardiovascular mortality has been clearly established.3–5 During
recent years, growing insight into the properties of HDL has
changed our perception of HDL: from mere cholesterol carriers they have become global molecular players that
impact on many different facets of cellular behaviour. The
majority of the physiological functions of HDL influence the
cardiovascular system in a favourable way either directly or
indirectly. These pleiotropic beneficial effects of HDL on
metabolism, vasculature, and heart make them a bona fide
‘maintenance and repair party’ of the cardiovascular system.
The most common molecular explanation for the cardiovascular protection conferred by HDL has been their fundamental role in the reverse cholesterol transport process by
which excess cholesterol is shuttled from peripheral cells
to the liver either for elimination via biliary excretion or
reutilization in the entero-hepatic cycle.6 Especially
the uptake of cholesterol from macrophages via ABC-transporters and phospholipid transfer proteins prevents the
* Corresponding author. Tel: þ49 201 723 4414; fax: þ49 201 723 4413.
formation of foam cells in the atherosclerotic lesion,7 which
is one of the first steps in the pathogenesis of atherosclerosis.8 The uptake of excess cholesterol by HDL not only prevents the formation of new lesions, but also affects the
characteristics of established ones: high HDL-levels achieved
by raising their endogenous levels or via administration of
reconstituted, artificial HDL were shown to induce a more
stable plaque morphology,9 reduce plaque lipid core,10,11
and even promote plaque regression.12–14
However, there is clear evidence that HDL possess other
biological functions than reverse cholesterol transport,
which may independently contribute to the prevention of
cardiovascular risk. HDL exert potent anti-inflammatory,
anti-oxidative, anti-apoptotic, and vasodilatory properties,
which are mediated by a multitude of signalling events
HDL induce at the cellular level. Such properties may
confer protection in a variety of cardiovascular disease settings as diverse as atherosclerosis, diabetes, metabolic syndrome, reperfusion injury, reperfusion-induced arrhythmias,
and heart failure.15–17 Although intrinsic to the HDL particle,
the molecular basis for these pleiotropic functions is still
little understood and even less well mapped to the different
components of the HDL particle. The reasons lie in the complexity of the HDL subclasses, the substantial differences in
HDL composition among individuals, and the existence of a
variety of different biochemical entities inside HDL. This
HDL diversity has hampered straight-forward mechanistic
studies. Advanced protein analysis has shown that apart
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202
from the apolipoproteins apoAI, AII, AIV, E, CI to CIV, LI, M, F,
D, and H that are mainly involved in lipid metabolism, the
HDL particle contains a multitude of other proteins and
enzymes18,19 that have diverse functions associated with
immunity, the acute phase response, and complement regulation.18 Lipid profiling has revealed that in addition to free
and esterified cholesterol a variety of different lipids are
found in HDL including phospholipids [phosphatidylcholine,
phosphatidylethanolamine (PE), PE-based plasmalogen,
lysophosphatidylcholine, glycerophospholipid], free and
esterified fatty acids (mono- and triacylglycerols), and
different sphingolipids such as ceramide, sphingolipids/
sphingomyelin species,20 sphingosine-1-phosphate (S1P),
lysosulfatide, and sphingosylphosphorylcholine.21–23 This
review will concentrate on S1P as the main representative
of the sphingolipids identified in HDL, which has gained
special attention in the HDL field because of its ability to
mimic many HDL functions and, most importantly, to actually mediate several of the biological effects of HDL. This
revelation has come from the evidence that HDL employ
S1P-specific signalling pathways for implementation of
many of their physiological effects.
2. High-density lipoprotein is the major carrier
and acceptor of sphingosine-1-phosphate in
plasma
The major carrier of S1P in plasma is HDL, and plasma S1P
levels positively correlate with HDL-C, apoAI, and apoAII
levels.24 S1P occurs in plasma in a concentration of 200–
1000 nM22,24 and is contained mainly in HDL (50–70%)
and albumin (30%), followed by LDL and VLDL (,10%)
when calculated per unit amount of protein.21 Accordingly,
the concentration of S1P within different lipoproteins
varies strongly: for HDL, the S1P concentration has been calculated as 140–300 pmol/mg protein (HDL-C concentrations
in plasma of 40–70 mg/dL correspond to 0.8–1.2 mg
HDL-protein/mL); for LDL and VLDL, S1P concentrations of
40 and 25 pmol/mg protein, respectively, have been estimated.22,23 When compared on a ‘per particle’ basis, HDL
carry seven-fold less S1P than LDL (9 vs. 65 mmol/mol)
as calculated on the basis of 33 mM/L particles for HDL and
1500 nM/L for LDL, respectively, which correspond to 44
and 135 mg/dL HDL-C and LDL-C, respectively.21,25
However, it must be considered that there are 22-fold
more HDL-particles than LDL-particles in plasma making
HDL the primary source of S1P-exposure to cells. Any
exogenous administration of HDL and LDL in physiological
ratios would equal an application of five-fold higher S1P
amounts administered with HDL than with LDL and distributed among 22-fold more HDL than LDL particles. Thus there
are major differences in the biochemical packaging and biological activity of S1P dependent on the lipoprotein carrier.
One clear indication for this is the protection against myocardial reperfusion injury conferred by HDL-associated but
not LDL-associated S1P.26 Of all HDL fractions, HDL3—the
small dense HDL particles—carry the highest amount of S1P
with 2–3-fold higher S1P levels compared with HDL2 at a
molar basis (40–50 mmol S1P/mol HDL3 compared with 15–
20 mmol S1P/mol HDL2).27
The major source of plasma S1P are haematopoietic cells
(mainly erythrocytes, platelets, and leukocytes) but
K. Sattler and B. Levkau
vascular and lymphatic endothelial cells can also synthesize
and release S1P.28,29 Inside the cell S1P moves freely among
membranes but needs transport mechanisms for translocation to the outer leaflet of the cytoplasmic membrane
because of the low propensity for spontaneous flip-flop.30,31
ABC-type transporters have been suggested to play a role in
S1P export in some cell types such as platelets and mast
cells,32,33 but whether they participate in the homeostasis
of extracellular and specifically plasma S1P is unknown,
especially as plasma S1P levels are not altered in any of
the knockout mice for ABCA1, ABCA7, or ABCC1.34 The affinity of HDL for S1P is extremely high compared with other
plasma carriers at a molar basis making them the primary
acceptor of plasma-borne S1P (our unpublished observations).
On the following pages, we will review the cardiovascular
effects of HDL specifically in respect to the possibility that
they may be mediated either partially or entirely by the
S1P content of HDL. To do this, we will ask not only if S1P
may mimic effects of HDL but rather explore how much of
the HDL effect can be abolished if S1P receptor signalling
is interfered with. Vice versa, we will try to convey which
of the genuine HDL effects may be S1P-independent. Furthermore, we will attempt to discriminate between the
functional properties of ‘free’ S1P in contrast to
HDL-associated S1P, which appear to de distinct. Finally,
we will discuss the potential benefits and limitations of
S1P analogues as a new class of functional HDL mimetics
for the therapy of cardiovascular diseases.
3. Regulation of arterial tone
The most essential cellular messenger for the regulation of
arterial tone induced by HDL is nitric oxide (NO). Native or
reconstituted HDL have been shown to induce endotheliumdependent NO-mediated vasorelaxation in isolated mouse
arteries ex vivo 23,35 and to promote flow-induced vasodilation in hypercholesterolemic36 and HDL-deficient37
patients, respectively, via direct or indirect effects on endothelial nitric oxide synthase (eNOS) function. Furthermore,
NO-dependent increases in myocardial perfusion in vivo
have also been measured after administration of human
HDL to mice.38
Induction of NO production by HDL in endothelial cells and
vasodilation in isolated vessels is induced by a molecular
mechanism completely dependent on the binding of HDL
to the scavenger receptor type I (SR-BI).35 The resulting
cholesterol efflux promotes phosphorylation of eNOS at
multiple sites35,39,40 in a process regulated by phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) and mitogenactivated protein (MAP) kinases.41,42 As the two main
binding partners for SR-BI on HDL apoAI and apoAII were
unable to activate eNOS-mediated vasodilation,35 it must
be concluded that either the sole binding of HDL to SR-BI
alone via apoA is not sufficient for eNOS activation or
that another constituent of HDL must exist that can
activate eNOS. As it turns out, both possibilities are
correct. ApoAI needs to be packaged together with 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) to be able to
induce cholesterol efflux-dependent SR-BI-mediated eNOS
activation.39,40 However, is still unknown how exactly the
cholesterol binding to SR-BI and its efflux leads to eNOS activation. Cholesterol efflux to HDL mediated by ABCG1 has
also been shown to preserve eNOS functionality but, again,
HDL-associated S1P in cardiovascular protection
the exact mechanism has also remained elusive.43 This
leaves us with the possibility that cholesterol efflux per se
may be more important for eNOS function than the actual
type of transporter mediating it. The requirements for the
second postulate—that of an enigmatic HDL-constituent
that is necessary for eNOS activation—were fulfilled by the
discovery of S1P inside HDL,21 and the finding that HDL can
mediate eNOS activation via S1P receptors.23 While the previously described loss of vasodilation after HDL-delipidation
and the ability of S1P to activate eNOS have been hints and
circumstantial evidence,21,23,44,45 the ultimate proof was
provided by the observation that 50% of HDL-mediated
vasodilation is lost in mice deficient for the S1P receptor
S1P3.23 While the vasodilatory effect of free S1P used as a
HDL mimic was completely abolished in S1P3-deficient
mice,23 the nature of the remaining S1P3-independent
but HDL-mediated vasodilation still remains enigmatic.
In vitro, augmented NO production by HDL after statin treatment has been attributed to the upregulation of another S1P
receptor, S1P1, while S1P3 or SR-BI appeared to play no
role.46 However, siRNA to S1P1 inhibited only basal and not
statin-induced NO production,46 making such conclusions
difficult to generalize, especially as clear defects in eNOS
signalling after HDL stimulation were detected in endothelial cells derived from S1P3-deficient mice.23
Numerous studies have been performed on the direct vasoactive effects of S1P alone. The consensus is that exogenous
S1P is able to induce vasoconstriction in isolated resistance
vessels (mesenteric, cerebral, and coronary arteries) but
not in conduit vessels (aorta, carotid, and femoral arteries)
in tension myograph studies through actions on vascular
smooth muscle cells (VSMC).47 When vasoconstriction is
induced by adrenergic stimulation in the same setting (e.g.
by pre-contracting aortae with norepinephrine), S1P and
S1P mimetics are able to induce vasodilation via eNOS activation in endothelial cells.23,48,49 In addition, intrinsic S1P
sources in the vascular wall appear to play a role both in
the homeostatic regulation of basal tone in resistance
vessels and the myogenic response thus ensuring constant
blood supply to the periphery.50,51 The sources of S1P presented to the vessel wall range from locally produced
endogenous S1P29,51 to systemic, free of HDL-packaged
S1P.47 This suggests that S1P exerts different and at times
counteractive effects on arterial tone that are mediated by
different cell types and depend on the underlying basal
tone and vascular bed. These S1P effects are dynamically
integrated into the overall regulation of regulation of vessel
tone.47 Their consequence is a constant fine-tuning of blood
flow in the periphery by local and systemic S1P.47
4. Endothelial barrier integrity and
angiogenesis
Both native and reconstituted HDL have been shown to
induce capillary tube-formation via the Ras/Raf/ERK and
Akt/ERK/eNOS pathway and to promote endothelial cell
proliferation in vitro.52,53 In addition, HDL was shown to
augment endothelial cell motility and endothelial barrier
integrity, with both effects being partially mediated by
S1P1 as concluded from studies with pharmacological antagonists.54 It would not surprise if the S1P content of HDL
acted as a functional mediator of HDL-induced angiogenesis
203
and endothelial integrity because there is ample evidence
that S1P promotes angiogenesis, migration, and proliferation in endothelial cells55,56 and enhances endothelial
integrity and barrier function.57–59 This appears to be S1P
receptor subtype-specific as S1P1 and S1P3 strengthen the
formation of endothelial cell junctions59–61 while S1P2
weakens them.62,63 Several observations have also linked
transient S1P-mediated Ca2þ increases to endothelial
barrier stabilization and eNOS activation.45,61 Both processes are closely interrelated as the sealing of the endothelial barrier and prevention of microvascular leakage are
inherent to NO. Since HDL have been shown to induce
both Ca2þ mobilization and NO production in a partially
S1P3-dependent manner,23 any of their effects on vascular
integrity could be partially mediated by their S1P content.
Other well-known HDL effects on the endothelium such as
promotion of proliferation and protection against apoptosis
may further help to preserve and promote endothelial integrity.64,65 The recently discovered stimulatory effect of HDL
on endothelial progenitor cells (EPC) may be one more
source of endothelial protection and repair.66 Reconstituted
HDL have been shown to stimulate differentiation of
human peripheral mononuclear cells into EPC, and
enhance ischaemia-induced angiogenesis in the murine hindlimb ischaemia model,53 In the same model, S1P and its analogue FTY720 phosphate were shown to stimulate the
capacity of therapeutically administered patient-derived
EPC to improve blood flow recovery and neovascularization,
but lost their effect when EPC from S1P3-deficent mice were
used.67 Although the crucial experiment of testing the
HDL effect in S1P3-deficient mice is still missing, we
cannot avoid succumbing to the charm of possible causal
interrelationships.
5. Anti-oxidative and cytoprotective effects
An important feature of HDL is their ability to reduce oxidative stress caused by the accumulation of deleterious
oxygen radicals (ROS) and oxidatively damaged lipids and
proteins.68 HDL particles carry anti-oxidative enzymes such
as paraoxonase-1 and -3, and platelet-activating factor
acetylhydrolase (PAF-AH), which counteract the oxidation
of proteins, especially that of LDL,69,70 and prevent atherosclerotic lesion formation71 and myocardial injury.72
Recently, HDL were shown to inhibit genuine ROS production
and protect endothelial cells against apoptosis.44,73,74 Both
effects have been linked to S1P because the HDL fraction
carrying S1P was the most efficacious one,44 and vice
versa, the LDL oxidation and oxLDL-induced apoptosis
were best attenuated by the HDL subclass with the highest
S1P/sphingomyelin ratio: the small dense HDL3.27 While
the signalling mechanisms by which HDL and its sphingolipids
protect endothelial cells were identified to be Akt and
NO-dependent,44,73,74 the first direct evidence of a causal
contribution of the S1P content of HDL to cytoprotection
was provided by experiments showing that inhibition of
NAD(P)H oxidase by HDL as preponderant source of ROS in
the vasculature was S1P3-dependent.75 Furthermore, HDL
via its S1P content also inhibited the NAD(P)H oxidasedependent synthesis of thrombin-induced monocyte chemotactic protein-1 (MCP-1), the key chemokine in monocyte
recruitment to atherosclerotic lesions.75 While free S1P
also inhibited NAD(P)H oxidase activation and MCP-1
204
production,75 it did not inhibit the increased basal production of MCP-1 in diabetic endothelial cells.76,77 In
respect to apoptosis, free S1P is clearly a potent survival
factor in endothelial cells.44,73,74
6. Inflammatory cell adhesion to activated
endothelium
Leukocyte–endothelial interactions occur in a complex
multi-step process mediated by several adhesion receptors.
HDL restrain leukocyte adhesion by reducing these interactions in vitro and in vivo through inhibition of adhesion
molecule expression and affinity.78 HDL have been reported
to reduce endothelial adhesiveness in apolipoprotein
E-deficient mice (ApoE2/2 ) in vivo, 79 to inhibit binding
and transmigration of monocytes to cytokine-activated
endothelium, and to reduce the expression of endothelial
adhesion molecules such as VCAM-1, ICAM-1, and E-selectin
in vitro.26,80–82 HDL were also shown to inhibit expression
of CD11b on the monocyte surface83 as well as that of
MCP-1 in VSMC.75 The biological significance of the antiadhesive effect of HDL in cardiovascular biology is eminent
in two major disease complexes: atherosclerosis and acute
vascular inflammation. Although it is difficult to evaluate
the contribution of the anti-adhesive effects of HDL to
atheroprotection separately from all other HDL effects,
administration of native and reconstituted HDL has been
shown to reduce plaque volume and promote lesion stabilization in patients9,10 and animal models84,85 with clear antiinflammatory effects on plaque composition. The second
disease complex to study effects of HDL on adhesion—
acute vascular inflammation—can be more easily simulated
in animal models in vivo, e.g. by application of TNFa or by
inducing post-ischaemic inflammation. Both native human
HDL and HDL mimetics consisting of apoAI-Milano and POPC
have been shown to reduce inflammation in such models as
shown for the protection against ischaemia–reperfusion
injury of the myocardium26,86 and kidney,87 and for the prevention of organ injury in haemorrhagic shock.88
As the expression of many adhesion molecules are regulated
by NF-kB and ROS-dependent mechanisms, HDL are perfectly
equipped for interfering with them by their capacity to induce
NO and prostacyclin (PGI2) production, inhibit ROS generation, and promote ROS elimination. Indeed, both NO and
PGI2 have been shown to mediate the anti-adhesive effect
of HDL in vitro and in vivo.26,82 Of the HDL constituents
implicated as mediators, PAF-AH has been shown to
participate in the process by increasing the anti-oxidative
capacity of HDL towards oxidation products contained
in pro-atherogenic lipoproteins.70,79 More recently, S1P
has joined the group of potentially anti-adhesive
HDL-compounds. However, the role of HDL-associated S1P in
the regulation of inflammatory cell adherence is complex
and not always congruent with that of free S1P. It has been
clearly shown that HDL26,89,90 and exogenous free S1P76,90
inhibit TNFa-induced adhesion molecule expression and
inflammatory cell adherence. The attenuation of the inhibitory effect of HDL on TNFa-induced adhesion molecule
expression by siRNA against S1P1 and S1P3 in vitro supports a
role for HDL-associated S1P in mediating this effect.90
In vivo, inhibition of post-ischaemic inflammation by HDL
was abolished in S1P3-deficient mice.26 However, the issue
K. Sattler and B. Levkau
becomes complicated, at least in vitro, when we take into
account that TNFa has been shown to induce adhesion molecule expression by activating sphingosine kinase-1, and
that free S1P by itself stimulates the expression of VCAM-1
and ICAM-1.90–93 Both effects—the TNFa-mediated and the
free S1P-mediated—can be inhibited by HDL,90 which
depends both on SR-BI-mediated NO generation and NF-kB
inhibition.90 Two explanations have been attempted to reconcile the inflammation-promoting effect of free S1P with the
inflammation-inhibitory effect of HDL and HDL-associated
S1P. The first one postulates the existence of yet unknown
pro-inflammatory of intracellular S1P that is generated after
TNFa-stimulation of sphingosine kinase-1. In this case, HDL
would inhibit TNFa-activated sphingosine kinase-1 (again by
yet unknown mechanisms), which would then prevent the
increase of intracellular S1P.89,91 The second explanation
suggests that S1P may exert two opposing effects on adhesion
molecule expression via engagement of different receptors:
accordingly, S1P1 would mediate the inhibitory effect of
free S1P and HDL-bound S1P on TNFa-induction of adhesion
molecules, while S1P3 would mediate the stimulatory effect
of free S1P on adhesion molecules; in this scenario, G12/13 proteins that are activated only by S1P3 and not S1P1 would
provide the molecular bias for pro-adhesive S1P effects.90
However, several questions remain unanswered. Why does
free S1P preferentially activate pro-inflammatory signals
when the Kds of S1P1 and S1P3 are similar and S1P1 is more
abundant than S1P3 on endothelial cells? Why should only
NO-generation mediated by SR-BI and not that mediated by
S1P1 and S1P323,94 be involved in the inhibitory effect of HDL
on TNFa? Could HDL be inhibiting any inflammatory S1P
effects simply by ‘defusing’ it through incorporation before
it could reach its receptors? Fortunately, the effects of free
S1P on adhesion to inflamed endothelium in vivo are much
more straightforward: S1P inhibits TNFa-mediated inflammatory cell adhesion in large vessels after TNFa stimulation76,77
and attenuates neutrophil recruitment to post-ischaemic
inflammation during myocardial reperfusion injury.26 Interestingly, S1P3-deficiency abrogated completely not only
S1P-mediated reperfusion injury but also that conferred
by HDL, suggesting that under the conditions of rather mild
myocardial injury caused predominately by endothelial
cell damage, the S1P-content of HDL by engaging
endothelial S1P3 accounts for the entire HDL-mediated
cardioprotection.26
7. Prostaglandins
A different mechanism of promoting vasorelaxation besides
endothelial NO production lies in the ability of HDL to induce
the synthesis of the functional antagonist of thromboxane A2
prostacyclin (PGI2) in VSMC95 and endothelial cells96 by upregulation of cyclooxygenase-2 (COX-2) and the p38 MAP kinase
pathway.95,97 PGI2 exerts its action through binding to the
G-protein coupled prostacyclin receptors IP and EP with
subsequent increases of intracellular cAMP and activation of
potassium channels.98,99 Thus PGI2 not only promotes vasodilation but inhibits VSMC migration100,101 and platelet activation,102 and suppresses the production of pro-inflammatory
cytokines.103 Clinically, the vasodilator capacity of PGI2 is
applied in the therapy of pulmonary hypertension.104 PGI2
also affects cardiomyocyte biology as activation of cAMP by
the IP-receptor inhibits cardiomyocyte hypertrophy,105 while
HDL-associated S1P in cardiovascular protection
the EP-receptor protects cardiomyocytes from damage or death
from oxidative stress by opening of ATP-dependent potassium
channels in the mitochondria.106 Interestingly, HDL have been
shown to promote PGI2 production in the myocardium of isolated, Langendorff-perfused hearts,107,108 which has been
suggested to partially account for the protection HDL confer
against ischaemia/reperfusion injury in the same model.108
For the induction of PGI2 production by HDL, their protein composition seems to be important as HDL from hypoalphalipoproteinemic patients are apparently less capable in inducing PGI2
than HDL from healthy subjects.109 Again, a lipid factor inside
HDL has been implied in the induction of PGI2 as delipidation
of HLD has been shown to abolish the effect.110 The successive
identification of this lipid factor as S1P has been due to the
ability of S1P2 and S1P3 receptor antagonists to inhibit
HDL-induced COX-2-mediated PGI2 release.111–113
In contrast, the effects of free S1P on COX-2 and production of inflammatory prostaglandins are quite to the contrary. There is a large body of literature clearly implicating
sphingosine kinase-1-generated S1P in mediating the effects
of TNFa on the induction of COX-2 and the subsequent production of inflammatory prostaglandins such as PGE2.114,115
Knockdown of S1P phosphatase or S1P lyase augmented prostaglandin production along with the increase in S1P
levels.114 This suggests that free S1P mediates COX-2dependent pro-inflammatory effects of cytokines.
8. Direct effects on the heart
Any direct, primary cardioprotective effects of HDL that
target specifically the myocardium must be distinguished
from those secondary to the anti-atherogenic effect of HDL.
While this is easily achieved under experimental conditions
where myocardial ischaemia is induced, e.g. by mechanical
occlusion of a coronary artery, it becomes extremely
difficult when epidemiological human studies are considered. However, there is evidence in favour of direct
atherosclerosis-independent cardioprotection mediated by
HDL and even some evidence in favour of S1P being its
mediator. Elevation of HDL for 16 weeks is considered short
in respect to epidemiological studies but has proved beneficial in patients with acute coronary syndromes in the
MIRACL trial, where a 1.4% risk reduction for recurrent
adverse events was observed for each 1 mg/dL increment of
HDL-C.116 Even shorter follow-up periods (30 days) have led
to a lower incidence of mortality and major adverse cardiac
events, respectively, in patients with high HDL-C levels
compared with low HDL-C levels after implantation of a
drug-eluting stent for acute coronary syndromes.117 The
most recent study from our laboratory has shown that high
HDL-C levels reduced the risk for myocardial injury during
elective percutaneous coronary intervention and improved
long-term prognosis when such injury did occur (K. Sattler
et al., submitted for publication). Although these beneficial
effects may be due to stabilization of vulnerable lesions by
HDL, they also raise the question whether HDL may exert
beneficial effects on the myocardium directly. In fact, the
following observations argue in favour of such direct cardioprotective effect of HDL. Both in healthy individuals and
patients with coronary artery disease, a positive association
between HDL-C levels and left ventricular function has been
observed.118,119 Although a mechanism has not been
defined, the NO-dependent increase in cardiac perfusion by
205
HDL38 may be involved as NO is important for maintenance
of normal left ventricular function in healthy individuals
in vivo.120 More direct evidence is provided by studies in
which exogenous administration of native or reconstituted
HDL improved functional recovery in isolated hearts after
ischaemia/reperfusion.108,121 A concomitant enhancement of
PGI2 release has been observed and ‘scavenging’ of myocardial
TNFa by HDL proposed as possible explanation. The straightest
argument in favour of direct HDL effects on the myocardium
comes from in vivo studies of ischaemia/reperfusion, where
administration of HDL potently reduced infarct size in an
NO-dependent manner by inhibiting both post-ischaemic
inflammation and cardiomyocyte apoptosis.26 These effects
were mediated by the S1P3 receptor as HDL conferred no protection in S1P3-deficient mice.26 This is to our knowledge the
first report to attribute the direct HDL effects on the heart to
their S1P content. S1P itself has been clearly shown to be cardioprotective in the same and several other models,122,123
leading us to the suggestion that HDL may be viewed as a
carrier of cardioprotective S1P that is made available to the
endangered heart whenever and wherever needed.124
Clinically, ischaemia/reperfusion injury to the heart is
extremely dangerous because of the increased arrhythmogenicity of the injured heart. Here, HDL has proved beneficial as well: administration of HDL was shown to
dramatically decrease the incidence of ischaemia/
reperfusion-induced ventricular arrhythmias in isolated perfused hearts by a mechanism possibly involving PGI2 and
NO.125,126 In contrast to the advantageous HDL effect, the
S1P1 agonist SEW2871 was demonstrated to induce irreversible tachyarrhythmias in the reperfusion period.127 However,
SEW2871 was used at very high concentrations (1 mM),
where receptor-promiscuous or even unspecific effects
cannot be excluded. With this in mind, HDL and S1P1 agonists appear to have divergent arrhythmogenic effects.
The effect of HDL on heart rate is difficult to obtain from
complex epidemiological studies but there seems to be a
negative correlation: in middle-aged, sedentary men the
resting heart rate was inversely correlated with plasma
HDL-C levels (especially HDL2 and HDL3),128 while after exercise, heart rate recovery was shown to be inversely related
to the plasma triglyceride-to-HDL-C ratio.129 From the
different effects S1P has on ion currents, its stimulatory
effect on the inward rectifier potassium current (IK.ACh)
results in a reduction of spontaneous pacing rate.130 Its
inhibitory effect on the isoproterenol-induced increase in
currents through L-type calcium channels (ICa,L) and the
hyperpolarization-activated inward current (If) in an attenuation of the positive chronotropic effects of b-adrenergic
stimulation in sino-atrial node cells and ventricular myocytes.130,131 S1P analogues such as FTY720 phosphate
induce transient bradycardia in mice and men,132,133 and
the S1P receptor involved has been identified as S1P3.132
9. High-density lipoprotein is not
sphingosine-1-phosphate, and
sphingosine-1-phosphate is not high-density
lipoprotein: similarities and differences
Despite the unequivocal evidence that the S1P-content of
HDL is biologically active and accounts for several of the
HDL effects, there are clear functional differences
206
between free S1P and HDL-associated S1P, as well as
between native HDL and S1P associated with HDL. These
statements are based on observations demonstrating that
HDL have effects that are: (i) not at all or only partially
attributable to their S1P content; (ii) opposite to the
effect of free S1P; and (iii) even contrary to S1P effects in
general. Some of them have been discussed in the previous
chapters but we would like to explicitly underline these
three scenarios by representative examples. An illustration
for HDL effects that are independent of their S1P content
is the induction of cholesterol efflux in macrophages, the
most crucial factor in reverse cholesterol transport in the
artery wall: it has been shown that particles containing
only apoAI and POPC were as effective as HDL in promoting
reverse cholesterol transport,39,40 and that reconstituted
HDL without S1P was similarly effective in promoting cholesterol efflux as one containing S1P.134 An example of HDL
effects only partially attributable to S1P is difficult to find
when both the S1P-dependent and S1P-independent HDL
effects are synergistic. However, this has been done concerning the vasodilatory effect of HDL: there, only 50% of
the total vasodilation mediated by HDL was abolished in
S1P3-deficient arteries while that of free S1P was completely
abrogated.23 Nevertheless, the entire HDL-dependent vasodilation (both S1P-dependent and S1P-independent) was
completely reliant on eNOS and a functional SR-BI receptor.35 Thus 50% of HDL-mediated vasodilation is not
mediated by S1P but exerted by yet unknown mechanisms
or HDL constituents. Finally, an example of HDL effects
opposite to free S1P effects is the increase of cardiac perfusion by administration of HDL but its decrease by S1P.38
Lastly, an example for HDL being able to counteract S1P
effects in general has been discussed earlier in view of the
ability of HDL to inhibit S1P-induced adhesion molecule
expression.135
10. How does the interaction between
high-density lipoproteins and
sphingosine-1-phosphate occur, where does it
take place, and what consequences could it
have?
There are many unsolved questions on the nature of the
relationship between HDL and S1P. Why does HDL of all
other molecules in plasma carry most of the S1P? How
does the uptake of S1P by HDL take place? Where is S1P
located topographically in the HDL particle? How much of
it is biologically active? Plasma S1P levels are 20–100-fold
higher than the Kd value of its receptors.21,136 Accordingly,
studies have shown that the concentration of biologically
active S1P in plasma is much lower (40-fold) than that of
the total S1P concentration.21 This has led to the hypothesis
that plasma proteins ‘buffer’ the large amounts of S1P to
prevent erroneous activation of S1P receptors.137 On the
other hand, the evidence presented in the reviewed literature strongly suggests that HDL-associated S1P (representing
the majority of plasma S1P) is biologically active. How does
this fit together?
Outside of the plasma compartment, 2–3-fold elevated
local S1P levels have been shown at inflammation sites,
and suggested to occur by activation of sphingosine
kinase-1 through inflammatory mediators such as TNFa,
K. Sattler and B. Levkau
IL-1b, LPS, and thrombin.138,139 On site, S1P presumably
acts in a pro-inflammatory manner by inducing PGE2 and
adhesion molecules,91–93,114,115,135 retaining lymphocytes
at the inflammation site,140 and promoting coagulationinduced activation of dendritic cells in the lymphatics.141
Quite to the contrary but occurring simultaneously, the
same S1P acts in a negative feedback mechanism to limit
the increase in endothelial permeability associated with
inflammation139 by enhancing endothelial barrier function57,60,61 and inhibiting leukocyte adhesion.76,77 Therefore, locally produced S1P appears to be an important
determinant of the build-up, magnitude, and duration of
the inflammatory response.
The scenario we would like to propose for the functional interrelation between HDL and S1P is one in which
HDL act as the master regulator of local S1P concentrations by ‘sucking up’ excess S1P or even ‘snatching’ it
away from other carriers. HDL as well as other plasma
proteins have been suggested to act as ‘sinks’ for S1P,
thereby neutralizing any excess S1P and providing an
explanation for the much higher plasma levels of S1P
than those necessary for S1P receptor activation.21,142
From our own data, the capacity of HDL to take up S1P
is enormous (up to 10-fold higher than the actual
content in HDL per milligram of protein; unpublished
observations). Accordingly, the presence and local concentration of HDL would determine how much S1P is biologically active and where. The ‘where’ may be very
important because HDL and other lipoproteins are
present in the interstitial space in amounts that correspond to 25% of their plasma concentration (in the
case of HDL),143,144 and are known to circulate with the
lymph fluid.145 Remarkably, the concentration of lipoproteins increases several-fold in inflammatory exudates.146
This increase would enable HDL to remove the excess
S1P produced at sites of inflammation, buffer it and
carry it away, thus helping in the resolution of inflammation. However, there may be something more to HDL
than just that. All reported effects of HDL-associated
S1P are potentially beneficent for cardiovascular homeostasis, while vice versa, not a single deleterious effect
has been reported for HDL-bound S1P. In contrast, free,
HDL-unbound S1P has the propensity of exerting
pro-inflammatory, vasoconstrictive, and other potentially
adverse effects as reviewed here. In contrast to scenarios
suggested by others,142 we would argue that by incorporating free S1P in their macromolecular structure HDL may
not only neutralize the deleterious excess of S1P but may
also transform it from ‘bad’ free S1P to ‘good’
HDL-packaged S1P. Such benignity may require the
docking of HDL to cell surface receptors such as SR-BI in
order to allow presentation of HDL-associated S1P to adjacent S1P receptors. In this way a spatially confined activation of S1P receptors is achieved dependent on the
presence of HDL receptors and HDL-S1P content.
Obviously, this all has to be proven both by experimental
S1P distribution studies as well as human patient studies,
in which a ‘more’ of S1P-bound HDL will have to be
associated with a better prognosis of disease. In vitro
support for this hypothesis comes from the observation
that a clearly defined biological effect of HDL has been
shown to depend on the magnitude of S1P content
within the HDL particle: loading of HDL with exogenous
HDL-associated S1P in cardiovascular protection
S1P was shown to increase their ability to inhibit
oxLDL-induced apoptosis in endothelial cells.27
11. Is sphingosine-1-phosphate a marker of
dysfunctional high-density lipoproteins?
Several studies have led to the idea that the absolute level
of HDL-C is not the only criterion contributing to their
athero-protective effect but that an enigmatic attribute
termed ‘HDL-quality’ also exists.14,147,148 Some of these
studies refer to the observation that low HDL-C increase
risk in patients with low LDL-C levels but that vice versa,
high HDL-C does not necessarily decrease risk.149 Others
have observed a superior propensity of certain HDL
mutations such as apoAI type Milano to mediate cholesterol
efflux150 accompanied by an enhanced protection against
atherosclerosis.151 The quality aspect of HDL is mirrored
by the evidence that each known cardioprotective function
of HDL can become defective and give rise to functionally
impaired HDL.83,147,152 Such functionally impaired HDL particles have been described in patients with virtually all cardiovascular risk factors (metabolic syndrome, diabetes
mellitus, obstructive sleep apnoea).153–155 The biological
characteristics of dysfunctional HDL extend to many of the
known effects of HDL such as protection against LDL-oxidation and apoptosis,153,154 vasorelaxation, and macrophage
adhesion.156,157 Therapeutic interventions which have
shown to improve HDL dysfunctionality include treatments
with high-fibre/low saturated fat diets,158 statins,157 and
fibrates.159 The molecular origin of HDL dysfunction has
been suggested to lie in alterations of HDL composition
(e.g. apolipoprotein and lipid ratios) or in biochemical
changes of individual HDL components such as apoAI, for
which oxidative modifications and non-enzymatic glycation
have been described.147,152 So far, although S1P has
emerged as an important mediator of many regular HDL
functions, there are no epidemiological or clinical studies
that have analysed S1P levels in dysfunctional or even
normal HDL. Such studies are clearly needed to find out if
alterations of HDL-associated S1P participate in HDL dysfunctionality, and whether therapeutic treatments known
to improve HDL function may be doing so via raising their
S1P content. Finally, if S1P indeed proves important as a
marker of HDL dysfunctionality, then the S1P content
of HDL may itself constitute a novel predictor of
cardiovascular risk.
207
lesions162 in mice, and improve the anti-inflammatory properties of HDL in patients.163 ApoAI-Milano complexed with
POPC reduced ischaemia/reperfusion injury in rabbits,86
diminished the lipid core and macrophage content in
apoE2/2 mice,164 and decreased the volume and thickness
of atherosclerotic lesions in patients with overt coronary
artery disease.165 Therefore, apoAI mimetic peptides are
an increasingly important option for HDL-based therapy.
However, no matter which sort of apoAI mimetic has been
used in vitro or in vivo, the ultimate biochemical mechanisms for its beneficial effect may not be related to the
apoAI moiety alone. Lipid-free apoAI, apoAI mimetics,
reconstituted HDL, and small unilamellar phosphatidylcholine vesicles may all have the same in common: they
most certainly alter their composition once having entered
the plasma. In fact, the differences in biological potency
existing among them have been attributed to differences
in their lipidation profile.166 If so, then an uptake of S1P
from the local milieu could most certainly be part of this
lipidation process. Once inside the particle S1P may then
mediate part of the biological effects ascribed to the
apoAI mimetics. Studies are needed to determine how an
apoAI mimetic exactly changes its biophysical and biochemical configuration after entering plasma, and how much and
how fast does S1P integrate into the particle.
Based on such considerations, S1P analogues may be considered functional HDL mimetics.48 The S1P analogue FTY720
(fingolimod) is the first member of a new class of immunosuppressive drugs currently in phase III clinical trials for prevention of allograft rejection and phase II for multiple
sclerosis.167 In vitro and in vivo, FTY720 phosphate activates
four of the five S1P receptors and mimics several of the functional properties ascribed to HDL-associated S1P such as
vasodilation,168 inhibition of NAD(P)H oxidase and MCP-1
production,75 protection against ischaemia/reperfusion
injury,169,170 and attenuation of atherosclerosis.124,171,172
The major drawback of using FTY720 for cardiovascular
purposes is its immunosuppressive effect which, fortunately,
is exclusively mediated by S1P1. Therefore, employing
combinations of the upcoming receptor subtype-specific
S1P analogues as functional HDL-mimetics will allow their
consideration as tools for tailoring individual therapies for
cardiovascular diseases.
Conflict of interest: none declared.
Funding
12. Sphingosine-1-phosphate analogues as
functional high-density lipoprotein mimetics
The understanding that HDL quality is clinically important
has led to the development of HDL-based therapies. There
is a growing family of HDL surrogates such as reconstituted
HDL, apoAI, apoAI-Milano, and apoAI-mimetic peptides
designed to imitate the structural requirements for the
atheroprotective and anti-inflammatory properties of
HDL.148 Reconstituted HDL has been shown to reduce
volume and promote stabilization of atherosclerotic lesions
in animals84 and patients,9 and to improve endothelial dysfunction.36 The apoAI-mimetic peptide D-4F was shown to
promote HDL-mediated cholesterol efflux from macrophages,160 restore NO production,161 reduce atherosclerotic
This work was supported by the Deutsche Forschungsgemeinschaft
(LE940/4-1, LE940/3-1).
References
1. Barr D, Russ E, Eder H. Protein-lipid relationships in human plasma. II. In
atherosclerosis and related conditions. Am J Med 1951;11:480–493.
2. Boyd GS, Oliver MF. The circulating lipids and lipoproteins in coronary
artery disease. Postgrad Med J 1957;32:2–6. passim.
3. Assmann G, Schulte H, von Eckardstein A, Huang Y. High-density lipoprotein cholesterol as a predictor of coronary heart disease risk. The
PROCAM experience and pathophysiological implications for reverse
cholesterol transport. Atherosclerosis 1996;124(suppl.):S11–S20.
4. Jacobs DR Jr, Mebane IL, Bangdiwala SI, Criqui MH, Tyroler HA. High
density lipoprotein cholesterol as a predictor of cardiovascular disease
mortality in men and women: the follow-up study of the Lipid Research
Clinics Prevalence Study. Am J Epidemiol 1990;131:32–47.
208
5. Stensvold I, Urdal P, Thurmer H, Tverdal A, Lund-Larsen PG, Foss OP.
High-density lipoprotein cholesterol and coronary, cardiovascular and
all cause mortality among middle-aged Norwegian men and women.
Eur Heart J 1992;13:1155–1163.
6. Charlton-Menys V, Durrington PN. Human cholesterol metabolism and
therapeutic molecules. Exp Physiol 2008;93:27–42.
7. Lee-Rueckert M, Vikstedt R, Metso J, Ehnholm C, Kovanen PT,
Jauhiainen M. Absence of endogenous phospholipid transfer protein
impairs ABCA1-dependent efflux of cholesterol from macrophage foam
cells. J Lipid Res 2006;47:1725–1732.
8. Ross R. Atherosclerosis–an inflammatory disease. N Engl J Med 1999;
340:115–126.
9. Tardif JC, Gregoire J, L’Allier PL, Ibrahim R, Lesperance J, Heinonen TM
et al. Effects of reconstituted high-density lipoprotein infusions on coronary atherosclerosis: a randomized controlled trial. JAMA 2007;297:
1675–1682.
10. Shaw JA, Bobik A, Murphy A, Kanellakis P, Blombery P, Mukhamedova N
et al. Infusion of reconstituted high-density lipoprotein leads to acute
changes in human atherosclerotic plaque. Circ Res 2008;103:
1084–1091.
11. Phan BA, Chu B, Polissar N, Hatsukami TS, Yuan C, Zhao XQ. Association
of high-density lipoprotein levels and carotid atherosclerotic plaque
characteristics by magnetic resonance imaging. Int J Cardiovasc
Imaging 2007;23:337–342.
12. Choudhury RP, Rong JX, Trogan E, Elmalem VI, Dansky HM, Breslow JL
et al. High-density lipoproteins retard the progression of atherosclerosis
and favorably remodel lesions without suppressing indices of inflammation or oxidation. Arterioscler Thromb Vasc Biol 2004;24:1904–1909.
13. von Birgelen C, Hartmann M, Mintz GS, Baumgart D, Schmermund A,
Erbel R. Relation between progression and regression of atherosclerotic
left main coronary artery disease and serum cholesterol levels as
assessed with serial long-term (. or ¼12 months) follow-up intravascular ultrasound. Circulation 2003;108:2757–2762.
14. Nicholls SJ, Tuzcu EM, Sipahi I, Grasso AW, Schoenhagen P, Hu T et al.
Statins, high-density lipoprotein cholesterol, and regression of coronary
atherosclerosis. JAMA 2007;297:499–508.
15. Libby P. Managing the risk of atherosclerosis: the role of high-density
lipoprotein. Am J Cardiol 2001;88:3N–8N.
16. Barter PJ, Puranik R, Rye KA. New insights into the role of HDL as an
anti-inflammatory agent in the prevention of cardiovascular disease.
Curr Cardiol Rep 2007;9:493–498.
17. Mineo C, Deguchi H, Griffin JH, Shaul PW. Endothelial and antithrombotic actions of HDL. Circ Res 2006;98:1352–1364.
18. Vaisar T, Pennathur S, Green PS, Gharib SA, Hoofnagle AN, Cheung MC
et al. Shotgun proteomics implicates protease inhibition and complement activation in the antiinflammatory properties of HDL. J Clin
Invest 2007;117:746–756.
19. Rezaee F, Casetta B, Levels JH, Speijer D, Meijers JC. Proteomic analysis
of high-density lipoprotein. Proteomics 2006;6:721–730.
20. Wiesner P, Leidl K, Boettcher A, Schmitz G, Liebisch G. Lipid profiling of
FPLC-separated lipoprotein fractions by electrospray ionization tandem
mass spectrometry. J Lipid Res 2008.
21. Murata N, Sato K, Kon J, Tomura H, Yanagita M, Kuwabara A et al. Interaction of sphingosine 1-phosphate with plasma components, including
lipoproteins, regulates the lipid receptor-mediated actions. Biochem J
2000;352:809–815.
22. Okajima F. Plasma lipoproteins behave as carriers of extracellular sphingosine 1-phosphate: is this an atherogenic mediator or an antiatherogenic mediator? Biochim Biophys Acta 2002;1582:132–137.
23. Nofer JR, van der Giet M, Tolle M, Wolinska I, von Wnuck Lipinski K,
Baba HA et al. HDL induces NO-dependent vasorelaxation via the lysophospholipid receptor S1P3. J Clin Invest 2004;113:569–581.
24. Zhang B, Tomura H, Kuwabara A, Kimura T, Miura S, Noda K et al. Correlation of high density lipoprotein (HDL)-associated sphingosine
1-phosphate with serum levels of HDL-cholesterol and apolipoproteins.
Atherosclerosis 2005;178:199–205.
25. Freedman DS, Otvos JD, Jeyarajah EJ, Shalaurova I, Cupples LA, Parise H
et al. Sex and age differences in lipoprotein subclasses measured by
nuclear magnetic resonance spectroscopy: the Framingham Study. Clin
Chem 2004;50:1189–1200.
26. Theilmeier G, Schmidt C, Herrmann J, Keul P, Schafers M, Herrgott I
et al. High-density lipoproteins and their constituent, sphingosine-1phosphate, directly protect the heart against ischemia/reperfusion
injury in vivo via the S1P3 lysophospholipid receptor. Circulation 2006;
114:1403–1409.
K. Sattler and B. Levkau
27. Kontush A, Therond P, Zerrad A, Couturier M, Negre-Salvayre A, de
Souza JA et al. Preferential sphingosine-1-phosphate enrichment and
sphingomyelin depletion are key features of small dense HDL3 particles:
relevance to antiapoptotic and antioxidative activities. Arterioscler
Thromb Vasc Biol 2007;27:1843–1849.
28. Pappu R, Schwab SR, Cornelissen I, Pereira JP, Regard JB, Xu Y et al. Promotion of lymphocyte egress into blood and lymph by distinct sources of
sphingosine-1-phosphate. Science 2007;316:295–298.
29. Venkataraman K, Lee YM, Michaud J, Thangada S, Ai Y, Bonkovsky HL
et al. Vascular endothelium as a contributor of plasma sphingosine 1phosphate. Circ Res 2008;102:669–676.
30. Hannun YA, Obeid LM. Principles of bioactive lipid signalling: lessons
from sphingolipids. Nat Rev Mol Cell Biol 2008;9:139–150.
31. van Meer G, Voelker DR, Feigenson GW. Membrane lipids: where they
are and how they behave. Nat Rev Mol Cell Biol 2008;9:112–124.
32. Mitra P, Oskeritzian CA, Payne SG, Beaven MA, Milstien S, Spiegel S. Role
of ABCC1 in export of sphingosine-1-phosphate from mast cells. Proc
Natl Acad Sci USA 2006;103:16394–16399.
33. Kobayashi N, Nishi T, Hirata T, Kihara A, Sano T, Igarashi Y et al.
Sphingosine 1-phosphate is released from the cytosol of rat platelets
in a carrier-mediated manner. J Lipid Res 2006;47:614–621.
34. Lee YM, Venkataraman K, Hwang SI, Han DK, Hla T. A novel method to
quantify sphingosine 1-phosphate by immobilized metal affinity chromatography (IMAC). Prostaglandins Other Lipid Mediat 2007;84:154–162.
35. Yuhanna IS, Zhu Y, Cox BE, Hahner LD, Osborne-Lawrence S, Lu P et al.
High-density lipoprotein binding to scavenger receptor-BI activates
endothelial nitric oxide synthase. Nat Med 2001;7:853–857.
36. Spieker LE, Sudano I, Hurlimann D, Lerch PG, Lang MG, Binggeli C et al.
High-density lipoprotein restores endothelial function in hypercholesterolemic men. Circulation 2002;105:1399–1402.
37. Bisoendial RJ, Hovingh GK, Levels JH, Lerch PG, Andresen I, Hayden MR
et al. Restoration of endothelial function by increasing high-density
lipoprotein in subjects with isolated low high-density lipoprotein. Circulation 2003;107:2944–2948.
38. Levkau B, Hermann S, Theilmeier G, van der Giet M, Chun J, Schober O
et al. High-density lipoprotein stimulates myocardial perfusion in vivo.
Circulation 2004;110:3355–3359.
39. Assanasen C, Mineo C, Seetharam D, Yuhanna IS, Marcel YL, Connelly MA
et al. Cholesterol binding, efflux, and a PDZ-interacting domain of scavenger receptor-BI mediate HDL-initiated signaling. J Clin Invest 2005;
115:969–977.
40. Drew BG, Fidge NH, Gallon-Beaumier G, Kemp BE, Kingwell BA. Highdensity lipoprotein and apolipoprotein AI increase endothelial NO
synthase activity by protein association and multisite phosphorylation.
Proc Natl Acad Sci USA 2004;101:6999–7004.
41. Viswambharan H, Ming XF, Zhu S, Hubsch A, Lerch P, Vergeres G et al.
Reconstituted high-density lipoprotein inhibits thrombin-induced endothelial tissue factor expression through inhibition of RhoA and stimulation of phosphatidylinositol 3-kinase but not Akt/endothelial nitric
oxide synthase. Circ Res 2004;94:918–925.
42. Mineo C, Yuhanna IS, Quon MJ, Shaul PW. High density lipoproteininduced endothelial nitric-oxide synthase activation is mediated by
Akt and MAP kinases. J Biol Chem 2003;278:9142–9149.
43. Terasaka N, Yu S, Yvan-Charvet L, Wang N, Mzhavia N, Langlois R et al.
ABCG1 and HDL protect against endothelial dysfunction in mice fed a
high-cholesterol diet. J Clin Invest 2008;118:3701–3713.
44. Kimura T, Sato K, Kuwabara A, Tomura H, Ishiwara M, Kobayashi I et al.
Sphingosine 1-phosphate may be a major component of plasma lipoproteins responsible for the cytoprotective actions in human umbilical vein
endothelial cells. J Biol Chem 2001;276:31780–31785.
45. Igarashi J, Michel T. Sphingosine 1-phosphate and isoform-specific activation of phosphoinositide 3-kinase beta. Evidence for divergence and
convergence of receptor-regulated endothelial nitric-oxide synthase
signaling pathways. J Biol Chem 2001;276:36281–36288.
46. Igarashi J, Miyoshi M, Hashimoto T, Kubota Y, Kosaka H. Statins induce
S1P1 receptors and enhance endothelial nitric oxide production in
response to high-density lipoproteins. Br J Pharmacol 2007;150:
470–479.
47. Levkau B. Sphingosine-1-phosphate in the regulation of vascular tone: a
finely tuned integration system of S1P sources, receptors, and vascular
responsiveness. Circ Res 2008;103:231–233.
48. Tolle M, Levkau B, Kleuser B, van der Giet M. Sphingosine-1-phosphate
and FTY720 as anti-atherosclerotic lipid compounds. Eur J Clin Invest
2007;37:171–179.
49. Salomone S, Potts EM, Tyndall S, Ip PC, Chun J, Brinkmann V et al. Analysis of sphingosine 1-phosphate receptors involved in constriction of
HDL-associated S1P in cardiovascular protection
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
isolated cerebral arteries with receptor null mice and pharmacological
tools. Br J Pharmacol 2008;153:140–147.
Bolz SS, Vogel L, Sollinger D, Derwand R, Boer C, Pitson SM et al. Sphingosine kinase modulates microvascular tone and myogenic responses
through activation of RhoA/Rho kinase. Circulation 2003;108:342–347.
Peter BF, Lidington D, Harada A, Bolz HJ, Vogel L, Heximer S et al. Role
of sphingosine-1-phosphate phosphohydrolase 1 in the regulation of
resistance artery tone. Circ Res 2008;103:315–324.
Miura S, Fujino M, Matsuo Y, Kawamura A, Tanigawa H, Nishikawa H
et al. High density lipoprotein-induced angiogenesis requires the activation of Ras/MAP kinase in human coronary artery endothelial cells.
Arterioscler Thromb Vasc Biol 2003;23:802–808.
Sumi M, Sata M, Miura S, Rye KA, Toya N, Kanaoka Y et al. Reconstituted
high-density lipoprotein stimulates differentiation of endothelial progenitor cells and enhances ischemia-induced angiogenesis. Arterioscler
Thromb Vasc Biol 2007;27:813–818.
Argraves KM, Gazzolo PJ, Groh EM, Wilkerson BA, Matsuura BS, Twal WO
et al. High density lipoprotein-associated sphingosine 1-phosphate promotes endothelial barrier function. J Biol Chem 2008;283:25074–25081.
Rikitake Y, Hirata K, Kawashima S, Ozaki M, Takahashi T, Ogawa W et al.
Involvement
of
endothelial
nitric
oxide
in
sphingosine1-phosphate-induced angiogenesis. Arterioscler Thromb Vasc Biol
2002;22:108–114.
Wang F, Van Brocklyn JR, Hobson JP, Movafagh S, Zukowska-Grojec Z,
Milstien S et al. Sphingosine 1-phosphate stimulates cell migration
through a G(i)-coupled cell surface receptor. Potential involvement in
angiogenesis. J Biol Chem 1999;274:35343–35350.
McVerry BJ, Garcia JG. In vitro and in vivo modulation of vascular barrier
integrity by sphingosine 1-phosphate: mechanistic insights. Cell Signal
2005;17:131–139.
Hla T. Physiological and pathological actions of sphingosine 1-phosphate.
Semin Cell Dev Biol 2004;15:513–520.
Xu M, Waters CL, Hu C, Wysolmerski RB, Vincent PA, Minnear FL. Sphingosine 1-phosphate rapidly increases endothelial barrier function independently of VE-cadherin but requires cell spreading and Rho kinase.
Am J Physiol Cell Physiol 2007;293:C1309–C1318.
Singleton PA, Dudek SM, Chiang ET, Garcia JG. Regulation of sphingosine
1-phosphate-induced endothelial cytoskeletal rearrangement and
barrier enhancement by S1P1 receptor, PI3 kinase, Tiam1/Rac1, and
alpha-actinin. FASEB J 2005;19:1646–1656.
Mehta D, Konstantoulaki M, Ahmmed GU, Malik AB. Sphingosine
1-phosphate-induced mobilization of intracellular Ca2þ mediates rac
activation and adherens junction assembly in endothelial cells. J Biol
Chem 2005;280:17320–17328.
Sanchez T, Skoura A, Wu MT, Casserly B, Harrington EO, Hla T. Induction
of vascular permeability by the sphingosine-1-phosphate receptor-2
(S1P2R) and its downstream effectors ROCK and PTEN. Arterioscler
Thromb Vasc Biol 2007;27:1312–1318.
Skoura A, Sanchez T, Claffey K, Mandala SM, Proia RL, Hla T. Essential
role of sphingosine 1-phosphate receptor 2 in pathological angiogenesis
of the mouse retina. J Clin Invest 2007;117:2506–2516.
Seetharam D, Mineo C, Gormley AK, Gibson LL, Vongpatanasin W,
Chambliss KL et al. High-density lipoprotein promotes endothelial cell
migration and reendothelialization via scavenger receptor-B type I.
Circ Res 2006;98:63–72.
Suc I, Escargueil-Blanc I, Troly M, Salvayre R, Negre-Salvayre A. HDL and
ApoA prevent cell death of endothelial cells induced by oxidized LDL.
Arterioscler Thromb Vasc Biol 1997;17:2158–2166.
Tso C, Martinic G, Fan WH, Rogers C, Rye KA, Barter PJ. High-density
lipoproteins enhance progenitor-mediated endothelium repair in mice.
Arterioscler Thromb Vasc Biol 2006;26:1144–1149.
Walter DH, Rochwalsky U, Reinhold J, Seeger F, Aicher A, Urbich C et al.
Sphingosine-1-phosphate stimulates the functional capacity of progenitor cells by activation of the CXCR4-dependent signaling pathway via
the S1P3 receptor. Arterioscler Thromb Vasc Biol 2007;27:275–282.
Ottaviano FG, Handy DE, Loscalzo J. Redox regulation in the extracellular environment. Circ J 2008;72:1–16.
Reddy ST, Wadleigh DJ, Grijalva V, Ng C, Hama S, Gangopadhyay A et al.
Human paraoxonase-3 is an HDL-associated enzyme with biological
activity similar to paraoxonase-1 protein but is not regulated by oxidized lipids. Arterioscler Thromb Vasc Biol 2001;21:542–547.
Lee C, Sigari F, Segrado T, Horkko S, Hama S, Subbaiah PV et al. All ApoBcontaining lipoproteins induce monocyte chemotaxis and adhesion when
minimally modified. Modulation of lipoprotein bioactivity by
platelet-activating factor acetylhydrolase. Arterioscler Thromb Vasc
Biol 1999;19:1437–1446.
209
71. Aviram M. Interaction of oxidized low density lipoprotein with macrophages in atherosclerosis, and the antiatherogenicity of antioxidants.
Eur J Clin Chem Clin Biochem 1996;34:599–608.
72. Inoue K, Arai Y, Kurihara H, Kita T, Sawamura T. Overexpression of lectinlike oxidized low-density lipoprotein receptor-1 induces intramyocardial
vasculopathy in apolipoprotein E-null mice. Circ Res 2005;97:176–184.
73. Nofer JR, Levkau B, Wolinska I, Junker R, Fobker M, von Eckardstein A
et al. Suppression of endothelial cell apoptosis by high density lipoproteins (HDL) and HDL-associated lysosphingolipids. J Biol Chem 2001;
276:34480–34485.
74. Kwon YG, Min JK, Kim KM, Lee DJ, Billiar TR, Kim YM. Sphingosine
1-phosphate protects human umbilical vein endothelial cells from
serum-deprived apoptosis by nitric oxide production. J Biol Chem
2001;276:10627–10633.
75. Tolle M, Pawlak A, Schuchardt M, Kawamura A, Tietge UJ, Lorkowski S
et al. HDL-associated lysosphingolipids inhibit NAD(P)H oxidasedependent monocyte chemoattractant protein-1 production. Arterioscler Thromb Vasc Biol 2008;28:1542–1548.
76. Bolick DT, Srinivasan S, Kim KW, Hatley ME, Clemens JJ, Whetzel A et al.
Sphingosine-1-phosphate prevents tumor necrosis factor-falphagmediated monocyte adhesion to aortic endothelium in mice. Arterioscler Thromb Vasc Biol 2005;25:976–981.
77. Whetzel AM, Bolick DT, Srinivasan S, Macdonald TL, Morris MA, Ley K
et al. Sphingosine-1 phosphate prevents monocyte/endothelial interactions in type 1 diabetic NOD mice through activation of the S1P1
receptor. Circ Res 2006;99:731–739.
78. Barter PJ. Inhibition of endothelial cell adhesion molecule expression by
high density lipoproteins. Clin Exp Pharmacol Physiol 1997;24:286–287.
79. Theilmeier G, De Geest B, Van Veldhoven PP, Stengel D, Michiels C,
Lox M et al. HDL-associated PAF-AH reduces endothelial adhesiveness
in apoE2/2 mice. FASEB J 2000;14:2032–2039.
80. Park SH, Park JH, Kang JS, Kang YH. Involvement of transcription factors
in plasma HDL protection against TNF-alpha-induced vascular cell
adhesion molecule-1 expression. Int J Biochem Cell Biol 2003;35:
168–182.
81. Navab M, Imes SS, Hama SY, Hough GP, Ross LA, Bork RW et al. Monocyte
transmigration induced by modification of low density lipoprotein in
cocultures of human aortic wall cells is due to induction of monocyte
chemotactic protein 1 synthesis and is abolished by high density lipoprotein. J Clin Invest 1991;88:2039–2046.
82. Cockerill GW, Rye KA, Gamble JR, Vadas MA, Barter PJ. High-density
lipoproteins inhibit cytokine-induced expression of endothelial cell
adhesion molecules. Arterioscler Thromb Vasc Biol 1995;15:1987–1994.
83. Murphy AJ, Woollard KJ, Hoang A, Mukhamedova N, Stirzaker RA,
McCormick SP et al. High-density lipoprotein reduces the human monocyte inflammatory response. Arterioscler Thromb Vasc Biol 2008;28:
2071–2077.
84. Nicholls SJ, Cutri B, Worthley SG, Kee P, Rye KA, Bao S et al. Impact of
short-term administration of high-density lipoproteins and atorvastatin
on atherosclerosis in rabbits. Arterioscler Thromb Vasc Biol 2005;25:
2416–2421.
85. Nicholls SJ, Dusting GJ, Cutri B, Bao S, Drummond GR, Rye KA et al.
Reconstituted high-density lipoproteins inhibit the acute pro-oxidant
and proinflammatory vascular changes induced by a periarterial collar
in normocholesterolemic rabbits. Circulation 2005;111:1543–1550.
86. Marchesi M, Booth EA, Davis T, Bisgaier CL, Lucchesi BR. Apolipoprotein
A-IMilano and 1-palmitoyl-2-oleoyl phosphatidylcholine complex
(ETC-216) protects the in vivo rabbit heart from regional
ischemia-reperfusion injury. J Pharmacol Exp Ther 2004;311:
1023–1031.
87. Thiemermann C, Patel NS, Kvale EO, Cockerill GW, Brown PA,
Stewart KN et al. High density lipoprotein (HDL) reduces renal ischemia/reperfusion injury. J Am Soc Nephrol 2003;14:1833–1843.
88. Cockerill GW, McDonald MC, Mota-Filipe H, Cuzzocrea S, Miller NE,
Thiemermann C. High density lipoproteins reduce organ injury and
organ dysfunction in a rat model of hemorrhagic shock. FASEB J 2001;
15:1941–1952.
89. Xia P, Vadas MA, Rye KA, Barter PJ, Gamble JR. High density lipoproteins
(HDL) interrupt the sphingosine kinase signaling pathway. A possible
mechanism for protection against atherosclerosis by HDL. J Biol Chem
1999;274:33143–33147.
90. Kimura T, Tomura H, Mogi C, Kuwabara A, Damirin A, Ishizuka T et al.
Role of scavenger receptor class B type I and sphingosine 1-phosphate
receptors in high density lipoprotein-induced inhibition of adhesion
molecule expression in endothelial cells. J Biol Chem 2006;
281:37457–37467.
210
91. Xia P, Gamble JR, Rye KA, Wang L, Hii CS, Cockerill P et al. Tumor necrosis factor-alpha induces adhesion molecule expression through
the sphingosine kinase pathway. Proc Natl Acad Sci USA 1998;95:
14196–14201.
92. Miura Y, Yatomi Y, Ohmori T, Osada M, Ozaki Y. Independence of tumor
necrosis factor-alpha-induced adhesion molecule expression from sphingosine 1-phosphate signaling in vascular endothelial cells. J Thromb
Haemost 2004;2:1019–1021.
93. Shimamura K, Takashiro Y, Akiyama N, Hirabayashi T, Murayama T.
Expression of adhesion molecules by sphingosine 1-phosphate and histamine in endothelial cells. Eur J Pharmacol 2004;486:141–150.
94. De Palma C, Meacci E, Perrotta C, Bruni P, Clementi E. Endothelial nitric
oxide synthase activation by tumor necrosis factor alpha through
neutral sphingomyelinase 2, sphingosine kinase 1, and sphingosine 1
phosphate receptors: a novel pathway relevant to the pathophysiology
of endothelium. Arterioscler Thromb Vasc Biol 2006;26:99–105.
95. Vinals M, Martinez-Gonzalez J, Badimon L. Regulatory effects of HDL on
smooth muscle cell prostacyclin release. Arterioscler Thromb Vasc Biol
1999;19:2405–2411.
96. Spector AA, Scanu AM, Kaduce TL, Figard PH, Fless GM, Czervionke RL.
Effect of human plasma lipoproteins on prostacyclin production by cultured endothelial cells. J Lipid Res 1985;26:288–297.
97. Norata GD, Callegari E, Inoue H, Catapano AL. HDL3 induces
cyclooxygenase-2 expression and prostacyclin release in human endothelial cells via a p38 MAPK/CRE-dependent pathway: effects on
COX-2/PGI-synthase coupling. Arterioscler Thromb Vasc Biol 2004;24:
871–877.
98. Jackson WF, Konig A, Dambacher T, Busse R. Prostacyclin-induced vasodilation in rabbit heart is mediated by ATP-sensitive potassium channels. Am J Physiol 1993;264:H238–H243.
99. Schubert R, Serebryakov VN, Mewes H, Hopp HH. Iloprost dilates rat
small arteries: role of K(ATP)- and K(Ca)-channel activation by cAMPdependent protein kinase. Am J Physiol 1997;272:H1147–H1156.
100. Bulin C, Albrecht U, Bode JG, Weber AA, Schror K, Levkau B et al. Differential effects of vasodilatory prostaglandins on focal adhesions, cytoskeletal architecture, and migration in human aortic smooth muscle
cells. Arterioscler Thromb Vasc Biol 2005;25:84–89.
101. Kamio K, Liu X, Sugiura H, Togo S, Kobayashi T, Kawasaki S et al. Prostacyclin analogs inhibit fibroblast contraction of collagen gels through the
cAMP-PKA pathway. Am J Respir Cell Mol Biol 2007;37:113–120.
102. Tateson JE, Moncada S, Vane JR. Effects of prostacyclin (PGX) on cyclic
AMP concentrations in human platelets. Prostaglandins 1977;13:
389–397.
103. Zhou W, Hashimoto K, Goleniewska K, O’Neal JF, Ji S, Blackwell TS et al.
Prostaglandin I2 analogs inhibit proinflammatory cytokine production
and T cell stimulatory function of dendritic cells. J Immunol 2007;
178:702–710.
104. Opitz CF, Wensel R, Bettmann M, Schaffarczyk R, Linscheid M, Hetzer R
et al. Assessment of the vasodilator response in primary pulmonary
hypertension. Comparing prostacyclin and iloprost administered by
either infusion or inhalation. Eur Heart J 2003;24:356–365.
105. Ritchie RH, Rosenkranz AC, Huynh LP, Stephenson T, Kaye DM,
Dusting GJ. Activation of IP prostanoid receptors prevents cardiomyocyte hypertrophy via cAMP-dependent signaling. Am J Physiol Heart
Circ Physiol 2004;287:H1179–H1185.
106. Shinmura K, Tamaki K, Sato T, Ishida H, Bolli R. Prostacyclin attenuates
oxidative damage of myocytes by opening mitochondrial ATP-sensitive
Kþ channels via the EP3 receptor. Am J Physiol Heart Circ Physiol
2005;288:H2093–H2101.
107. Van Sickle WA, Wilcox HG, Malik KU, Nasjletti A. High density
lipoprotein-induced cardiac prostacyclin synthesis in vitro: relationship
to cardiac arachidonate mobilization. J Lipid Res 1986;27:517–522.
108. Calabresi L, Rossoni G, Gomaraschi M, Sisto F, Berti F, Franceschini G.
High-density lipoproteins protect isolated rat hearts from
ischemia-reperfusion injury by reducing cardiac tumor necrosis factoralpha content and enhancing prostaglandin release. Circ Res 2003;92:
330–337.
109. Shakhov Y, Larrue J, Perova N, Dorian B, Daret D, Shcherbakova I et al.
Prostacyclin-mediated effect of high density lipoproteins as cellular
cholesterol acceptors on aortic smooth muscle cells. J Mol Cell
Cardiol 1989;21:461–468.
110. Escudero I, Martinez-Gonzalez J, Alonso R, Mata P, Badimon L. Experimental and interventional dietary study in humans on the role of HDL
fatty acid composition in PGI2 release and Cox-2 expression by VSMC.
Eur J Clin Invest 2003;33:779–786.
K. Sattler and B. Levkau
111. Nodai A, Machida T, Izumi S, Hamaya Y, Kohno T, Igarashi Y et al. Sphingosine 1-phosphate induces cyclooxygenase-2 via Ca2þ-dependent, but
MAPK-independent mechanism in rat vascular smooth muscle cells. Life
Sci 2007;80:1768–1776.
112. Gonzalez-Diez M, Rodriguez C, Badimon L, Martinez-Gonzalez J. Prostacyclin induction by high-density lipoprotein (HDL) in vascular smooth
muscle cells depends on sphingosine 1-phosphate receptors: effect of
simvastatin. Thromb Haemost 2008;100:119–126.
113. Damirin A, Tomura H, Komachi M, Tobo M, Sato K, Mogi C et al. Sphingosine 1-phosphate receptors mediate the lipid-induced cAMP accumulation through cyclooxygenase-2/prostaglandin I2 pathway in human
coronary artery smooth muscle cells. Mol Pharmacol 2005;67:
1177–1185.
114. Pettus BJ, Bielawski J, Porcelli AM, Reames DL, Johnson KR, Morrow J
et al. The sphingosine kinase 1/sphingosine-1-phosphate pathway mediates COX-2 induction and PGE2 production in response to TNF-alpha.
FASEB J 2003;17:1411–1421.
115. Billich A, Bornancin F, Mechtcheriakova D, Natt F, Huesken D,
Baumruker T. Basal and induced sphingosine kinase 1 activity in A549
carcinoma cells: function in cell survival and IL-1beta and TNF-alpha
induced production of inflammatory mediators. Cell Signal 2005;17:
1203–1217.
116. Olsson AG, Schwartz GG, Szarek M, Sasiela WJ, Ezekowitz MD, Ganz P
et al. High-density lipoprotein, but not low-density lipoprotein cholesterol levels influence short-term prognosis after acute coronary syndrome: results from the MIRACL trial. Eur Heart J 2005;26:890–896.
117. Wolfram RM, Brewer HB, Xue Z, Satler LF, Pichard AD, Kent KM et al.
Impact of low high-density lipoproteins on in-hospital events and
one-year clinical outcomes in patients with non-ST-elevation myocardial
infarction acute coronary syndrome treated with drug-eluting stent
implantation. Am J Cardiol 2006;98:711–717.
118. Roes SD, Alizadeh Dehnavi R, Westenberg JJ, Lamb HJ, Mertens BJ,
Tamsma JT et al. Assessment of aortic pulse wave velocity and cardiac
diastolic function in subjects with and without the metabolic syndrome:
HDL cholesterol is independently associated with cardiovascular function. Diabetes Care 2008;31:1442–1444.
119. Kempen HJ, van Gent CM, Buytenhek R, Buis B. Association of cholesterol concentrations in low-density lipoprotein, high-density lipoprotein, and high-density lipoprotein subfractions, and of apolipoproteins
AI and AII, with coronary stenosis and left ventricular function. J Lab
Clin Med 1987;109:19–26.
120. Rassaf T, Poll LW, Brouzos P, Lauer T, Totzeck M, Kleinbongard P et al.
Positive effects of nitric oxide on left ventricular function in humans.
Eur Heart J 2006;27:1699–1705.
121. Marchesi M, Booth EA, Rossoni G, Garcia RA, Hill KR, Sirtori CR et al.
Apolipoprotein A-IMilano/POPC complex attenuates post-ischemic ventricular dysfunction in the isolated rabbit heart. Atherosclerosis 2008;
197:572–578.
122. Vessey DA, Kelley M, Li L, Huang Y, Zhou HZ, Zhu BQ et al. Role of sphingosine kinase activity in protection of heart against ischemia reperfusion injury. Med Sci Monit 2006;12:BR318–324.
123. Karliner JS. Toward solving the riddle: the enigma becomes less mysterious. Circ Res 2006;99:465–467.
124. Keul P, Sattler K, Levkau B. HDL and its sphingosine-1-phosphate content
in cardioprotection. Heart Fail Rev 2007;12:301–306.
125. Mochizuki S, Okumura M, Tanaka F, Sato T, Kagami A, Tada N et al.
Ischemia-reperfusion arrhythmias and lipids: effect of human highand low-density lipoproteins on reperfusion arrhythmias. Cardiovasc
Drugs Ther 1991;5(Suppl. 2):269–276.
126. Imaizumi S, Miura S, Nakamura K, Kiya Y, Uehara Y, Zhang B et al. Antiarrhythmogenic effect of reconstituted high-density lipoprotein against
ischemia/reperfusion in rats. J Am Coll Cardiol 2008;51:1604–1612.
127. Tsukada YT, Sanna MG, Rosen H, Gottlieb RA. S1P1-selective agonist
SEW2871 exacerbates reperfusion arrhythmias. J Cardiovasc Pharmacol
2007;50:660–669.
128. Williams PT, Haskell WL, Vranizan KM, Blair SN, Krauss RM, Superko HR
et al. Associations of resting heart rate with concentrations of lipoprotein subfractions in sedentary men. Circulation 1985;71:441–449.
129. Shishehbor MH, Hoogwerf BJ, Lauer MS. Association of triglyceride-toHDL cholesterol ratio with heart rate recovery. Diabetes Care 2004;
27:936–941.
130. Guo J, MacDonell KL, Giles WR. Effects of sphingosine 1-phosphate on
pacemaker activity in rabbit sino-atrial node cells. Pflugers Arch
1999;438:642–648.
131. Landeen LK, Dederko DA, Kondo CS, Hu BS, Aroonsakool N, Haga JH
et al. Mechanisms of the negative inotropic effects of sphingosine-1-
HDL-associated S1P in cardiovascular protection
132.
133.
134.
135.
136.
137.
138.
139.
140.
141.
142.
143.
144.
145.
146.
147.
148.
149.
150.
151.
152.
153.
phosphate on adult mouse ventricular myocytes. Am J Physiol Heart Circ
Physiol 2008;294:H736–H749.
Sanna MG, Liao J, Jo E, Alfonso C, Ahn MY, Peterson MS et al. Sphingosine 1-phosphate (S1P) receptor subtypes S1P1 and S1P3, respectively,
regulate lymphocyte recirculation and heart rate. J Biol Chem 2004;
279:13839–13848.
Budde K, Schmouder RL, Brunkhorst R, Nashan B, Lucker PW, Mayer T
et al. First human trial of FTY720, a novel immunomodulator, in
stable renal transplant patients. J Am Soc Nephrol 2002;13:1073–1083.
Matsuo Y, Miura S, Kawamura A, Uehara Y, Rye KA, Saku K. Newly developed reconstituted high-density lipoprotein containing sphingosine-1phosphate induces endothelial tube formation. Atherosclerosis 2007;
194:159–168.
Kimura T, Tomura H, Mogi C, Kuwabara A, Ishiwara M, Shibasawa K et al.
Sphingosine 1-phosphate receptors mediate stimulatory and inhibitory
signalings for expression of adhesion molecules in endothelial cells.
Cell Signal 2006;18:841–850.
Mandala S, Hajdu R, Bergstrom J, Quackenbush E, Xie J, Milligan J et al.
Alteration of lymphocyte trafficking by sphingosine-1-phosphate receptor agonists. Science 2002;296:346–349.
Sabbadini RA. Targeting sphingosine-1-phosphate for cancer therapy. Br
J Cancer 2006;95:1131–1135.
Hait NC, Oskeritzian CA, Paugh SW, Milstien S, Spiegel S. Sphingosine
kinases, sphingosine 1-phosphate, apoptosis and diseases. Biochim
Biophys Acta 2006;1758:2016–2026.
Tauseef M, Kini V, Knezevic N, Brannan M, Ramchandaran R, Fyrst H
et al. Activation of sphingosine kinase-1 reverses the increase in lung
vascular permeability through sphingosine-1-phosphate receptor signaling in endothelial cells. Circ Res 2008;103:1164–1172.
Ledgerwood LG, Lal G, Zhang N, Garin A, Esses SJ, Ginhoux F et al. The
sphingosine 1-phosphate receptor 1 causes tissue retention by inhibiting
the entry of peripheral tissue T lymphocytes into afferent lymphatics.
Nat Immunol 2008;9:42–53.
Niessen F, Schaffner F, Furlan-Freguia C, Pawlinski R, Bhattacharjee G,
Chun J et al. Dendritic cell PAR1-S1P3 signalling couples coagulation
and inflammation. Nature 2008;452:654–658.
Alewijnse AE, Peters SL. Sphingolipid signalling in the cardiovascular
system: good, bad or both? Eur J Pharmacol 2008;585:292–302.
Parini P, Johansson L, Broijersen A, Angelin B, Rudling M. Lipoprotein
profiles in plasma and interstitial fluid analyzed with an automated gelfiltration system. Eur J Clin Invest 2006;36:98–104.
Sloop CH, Dory L, Roheim PS. Interstitial fluid lipoproteins. J Lipid Res
1987;28:225–237.
Brunham LR, Kruit JK, Iqbal J, Fievet C, Timmins JM, Pape TD et al.
Intestinal ABCA1 directly contributes to HDL biogenesis in vivo. J Clin
Invest 2006;116:1052–1062.
Pfalzer B, Hamm H, Beisiegel U, Ostendorf P. Lipoproteins and apolipoproteins in human pleural effusions. J Lab Clin Med 1992;120:483–493.
Kontush A, Chapman MJ. Functionally defective high-density lipoprotein: a new therapeutic target at the crossroads of dyslipidemia, inflammation, and atherosclerosis. Pharmacol Rev 2006;58:342–374.
Navab M, Anantharamaiah GM, Reddy ST, Fogelman AM. Apolipoprotein
A-I mimetic peptides and their role in atherosclerosis prevention. Nat
Clin Pract Cardiovasc Med 2006;3:540–547.
Barter P, Gotto AM, LaRosa JC, Maroni J, Szarek M, Grundy SM et al. HDL
cholesterol, very low levels of LDL cholesterol, and cardiovascular
events. N Engl J Med 2007;357:1301–1310.
Favari E, Gomaraschi M, Zanotti I, Bernini F, Lee-Rueckert M,
Kovanen PT et al. A unique protease-sensitive high density lipoprotein
particle containing the apolipoprotein A-I(Milano) dimer effectively promotes ATP-binding Cassette A1-mediated cell cholesterol efflux. J Biol
Chem 2007;282:5125–5132.
Sirtori CR, Calabresi L, Franceschini G, Baldassarre D, Amato M,
Johansson J et al. Cardiovascular status of carriers of the apolipoprotein
A-I(Milano) mutant: the Limone sul Garda study. Circulation 2001;103:
1949–1954.
Ansell BJ, Fonarow GC, Fogelman AM. The paradox of dysfunctional
high-density lipoprotein. Curr Opin Lipidol 2007;18:427–434.
de Souza JA, Vindis C, Hansel B, Negre-Salvayre A, Therond P,
Serrano CV Jr et al. Metabolic syndrome features small, apolipoprotein
A-I-poor, triglyceride-rich HDL3 particles with defective anti-apoptotic
activity. Atherosclerosis 2008;197:84–94.
211
154. Nobecourt E, Jacqueminet S, Hansel B, Chantepie S, Grimaldi A,
Chapman MJ et al. Defective antioxidative activity of small dense
HDL3 particles in type 2 diabetes: relationship to elevated oxidative
stress and hyperglycaemia. Diabetologia 2005;48:529–538.
155. Tan KC, Chow WS, Lam JC, Lam B, Wong WK, Tam S et al. HDL dysfunction in obstructive sleep apnea. Atherosclerosis 2006;184:377–382.
156. Persegol L, Foissac M, Lagrost L, Athias A, Gambert P, Verges B et al. HDL
particles from type 1 diabetic patients are unable to reverse the inhibitory effect of oxidised LDL on endothelium-dependent vasorelaxation.
Diabetologia 2007;50:2384–2387.
157. Ansell BJ, Navab M, Hama S, Kamranpour N, Fonarow G, Hough G et al.
Inflammatory/antiinflammatory properties of high-density lipoprotein
distinguish patients from control subjects better than high-density lipoprotein cholesterol levels and are favorably affected by simvastatin
treatment. Circulation 2003;108:2751–2756.
158. Roberts CK, Ng C, Hama S, Eliseo AJ, Barnard RJ. Effect of a short-term
diet and exercise intervention on inflammatory/anti-inflammatory
properties of HDL in overweight/obese men with cardiovascular risk
factors. J Appl Physiol 2006;101:1727–1732.
159. Watts GF, Barrett PH, Ji J, Serone AP, Chan DC, Croft KD et al. Differential regulation of lipoprotein kinetics by atorvastatin and fenofibrate in
subjects with the metabolic syndrome. Diabetes 2003;52:803–811.
160. Navab M, Anantharamaiah GM, Reddy ST, Hama S, Hough G, Grijalva VR
et al. Oral D-4F causes formation of pre-fbetag high-density lipoprotein
and improves high-density lipoprotein-mediated cholesterol efflux and
reverse cholesterol transport from macrophages in apolipoprotein. Circulation 2004;109:3215–3220. E-Null Mice 10.1161/01.CIR.0000134275.
90823.87.
161. Ou J, Wang J, Xu H, Ou Z, Sorci-Thomas MG, Jones DW et al. Effects of
D-4F on vasodilation and vessel wall thickness in hypercholesterolemic
LDL receptor-null and LDL receptor/apolipoprotein A-I double-knockout
mice on Western diet. Circ Res 2005;97:1190–1197.
162. Navab M, Anantharamaiah GM, Hama S, Garber DW, Chaddha M, Hough G
et al. Oral administration of an Apo A-I mimetic Peptide synthesized
from D-amino acids dramatically reduces atherosclerosis in mice independent of plasma cholesterol. Circulation 2002;105:290–292.
163. Bloedon LT, Dunbar R, Duffy D, Pinell-Salles P, Norris R, DeGroot BJ et al.
Safety, pharmacokinetics, and pharmacodynamics of oral apoA-I
mimetic peptide D-4F in high-risk cardiovascular patients. J Lipid Res
2008;49:1344–1352.
164. Shah PK, Nilsson J, Kaul S, Fishbein MC, Ageland H, Hamsten A et al.
Effects of recombinant Apolipoprotein A-IMilano on aortic atherosclerosis in apolipoprotein E–deficient mice. Circulation 1998;97:780–785.
165. Nissen SE, Tsunoda T, Tuzcu EM, Schoenhagen P, Cooper CJ, Yasin M et al.
Effect of recombinant ApoA-I Milano on coronary atherosclerosis in
patients with acute coronary syndromes: a randomized controlled
trial. JAMA 2003;290:2292–2300.
166. Rye KA, Barter PJ. Antiinflammatory actions of HDL: a new insight.
Arterioscler Thromb Vasc Biol 2008;28:1890–1891.
167. Kappos L, Antel J, Comi G, Montalban X, O’Connor P, Polman CH et al.
Oral fingolimod (FTY720) for relapsing multiple sclerosis. N Engl J Med
2006;355:1124–1140.
168. Tolle M, Levkau B, Keul P, Brinkmann V, Giebing G, Schonfelder G et al.
Immunomodulator FTY720 induces eNOS-dependent arterial vasodilatation via the lysophospholipid receptor S1P3. Circ Res 2005;96:913–920.
169. Kaudel CP, Frink M, van Griensven M, Schmiddem U, Probst C,
Bergmann S et al. FTY720 application following isolated warm liver
ischemia improves long-term survival and organ protection in a mouse
model. Transplant Proc 2007;39:493–498.
170. Frink M, Kaudel CP, Hildebrand F, Pape HC, Klempnauer J, Winkler M
et al. FTY720 improves survival after transient ischemia and reperfusion
of the hind limbs. J Trauma 2007;63:263–267.
171. Nofer JR, Bot M, Brodde M, Taylor PJ, Salm P, Brinkmann V et al. FTY720,
a synthetic sphingosine 1 phosphate analogue, inhibits development of
atherosclerosis in low-density lipoprotein receptor-deficient mice. Circulation 2007;115:501–508.
172. Klingenberg R, Nofer JR, Rudling M, Bea F, Blessing E, Preusch M et al.
Sphingosine-1-phosphate analogue FTY720 causes lymphocyte redistribution and hypercholesterolemia in ApoE-deficient mice. Arterioscler
Thromb Vasc Biol 2007;27:2392–2399.