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Keywords:

  • Endothelium;
  • FTY720;
  • immunosuppression;
  • S1P;
  • S1P receptor;
  • sphingosine;
  • T-cell circulation

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

The novel immunomodulator FTY720 is effective in experimental models of transplantation and autoimmunity, and is currently undergoing Phase III clinical trials for prevention of kidney graft rejection. In contrast to conventional immunosuppressants, FTY720 does not impair T- and B-cell activation, proliferation and effector function, but interferes with cell traffic between lymphoid organs and blood. The molecular basis for the mode of action of the drug has only recently been established. FTY720, after phosphorylation, acts as a high-affinity agonist at the G protein-coupled sphingosine 1-phosphate receptor-1 (S1P1) on thymocytes and lymphocytes, thereby inducing aberrant internalization of the receptor. This renders the cells unresponsive to the serum lipid sphingosine 1-phosphate (S1P), depriving them from an obligatory signal to egress from lymphoid organs. As a consequence, lymphocytes are unable to recirculate to peripheral inflammatory tissues and graft sites but remain functional in the lymphoid compartment. In addition to the effects on lymphocyte recirculation, the drug acts on endothelial cells and preserves vascular integrity by enhancing adherens junction assembly and endothelial barrier function. The available data establish S1P1 as a key target for FTY720, and further point to therapeutically relevant effects of the drug on lymphocytes and vascular endothelium.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

Over the past 7 years, a large number of preclinical studies have demonstrated efficacy of the novel immunomodulator FTY720 in models of solid organ and islet transplantation, autoimmune disease (including multiple sclerosis and diabetes) and cancer (reviewed in 1, 2). A recently completed Phase II clinical trial indicated efficacy of the drug in de novo renal transplant patients (3); however, the clinical utility of the drug may be difficult to predict prior to completion of ongoing Phase III studies.

FTY720 (2-amino-2-(2-[4-octylphenyl]ethyl)-1,3- propanediol) was first synthesized in 1992 by chemical derivatization of myriocin (ISP-1), a metabolite of the ascomycete Isaria sinclairii (4). Unlike myriocin, FTY720 did not inhibit serine-palmitoyl-transferase, the first enzyme in sphingolipid biosynthesis (5). Subsequent studies showed that FTY720 did not impair antigen-driven T-cell activation and proliferation at therapeutically relevant concentrations (6,7), but that the drug produced lymphopenia in vivo by sequestering lymphocytes from blood and spleen into lymph nodes (LN) and Peyer's patches (PP) (6–8). This prompted speculation that the drug may act by accelerating the chemokine-dependent homing of cells into the lymphoid organs (8). However, subsequent studies showed that the sequestration occurred independent of the homing receptors CD62L (9), CCR7 (10), and CXCR5 (11), and the CCR7-ligand chemokines CCL19 and CCL21 (10).

It has recently been discovered that FTY720 is rapidly phosphorylated in vivo and that the FTY720-phosphate metabolite (FTY720-P) is the biologically active principle. FTY720-P targets a novel class of G protein coupled receptors (GPCRs) that are critically involved in lymphocyte traffic (12–14). In this review, we discuss in more detail the mechanism of action of FTY720, and outline potential advantages of the drug as compared with conventional immunosuppressive treatments.

G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

FTY720 shares striking structural homology with sphingosine 1-phosphate (S1P) (1) (Figure 1), a natural lysophospholipid that is present at high nanomolar (nM) concentrations in serum (15). S1P is released by platelets during platelet activation and thrombotic processes (16), mast cells during inflammatory activation (17) and other nonhematopoietic cells such as endothelial cells (EC) (18). S1P binds to five related GPCRs, termed S1P1–5 (formerly Edg-1, -5, -3, -6 and -8, respectively) (19). S1P1, S1P2 and S1P3 are widely expressed, with S1P1 being the dominant receptor on lymphocytes; S1P4 is specifically expressed in lymphoid tissue and S1P5 is present in spleen and white matter tracts of the central nervous system (CNS) (19). S1P receptors regulate a wide variety of important cellular functions, including cell survival, cytoskeletal rearrangements and cell motility (19).

image

Figure 1. Metabolic conversion of parent FTY720 to FTY720-P by sphingosine-kinases. FTY720 is a structural analog of sphingosine (Sph) and sphingosine 1-phosphate (S1P). S1P is generated via the intracellular ceramide (Cer) pathway, where Cer is formed through de novo biosynthesis or degradation of the cell membrane constituent sphingomyelin (SM). Cer is N-deacetylated to yield Sph, and both Sph and FTY720 are phosphorylated by sphingosine-kinases to yield S1P and FTY720-P, respectively. FTY720-P represents the biologically active principle of the drug.

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We and others have demonstrated that the phosphorylated FTY720 metabolite acts in vitro as an agonist at four of the five S1P receptors, namely S1P1, S1P3, S1P4, and S1P5, but not S1P2 (12,13). FTY720 was a substrate for sphingosine kinases (SphK) (12), with SphK2 being more active on the drug than SphK1 (20). Accordingly the drug was rapidly phosphorylated in vivo in rats, monkeys and humans, and ex vivo by rodent lymphoid tissues, whole blood and EC (12,13) (Figure 1). After oral application of FTY720, the blood levels of FTY720-P exceeded those of the parent compound two to fourfold (12). There was a linear relationship between the compound dose administered and the blood concentrations of FTY720 and FTY720-P. Studies with two chiral analogs of FTY720 [for structures see (1)] showed that only the biologically active R enantiomer AAL(R), but not the inactive S enantiomer AAL(S), was phosphorylated by SphK, and only the phosphorylated AAL(R) was capable of activating S1P receptors in vitro (12). Moreover, a nonhydrolyzable FTY720-phosphonate was biologically active in vivo (13), confirming that parent FTY720 was not required for activity. All together these data suggested that phosphorylation of FTY720 is essential for biological activity of the drug, and that agonistic activity of FTY720-P at S1P receptor(s) may explain its mechanism of action.

FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

Naïve T-cells regularly circulate between blood and lymphatic tissue in search of foreign antigen. The blood T-cells enter LN via high endothelial venules (HEV) and egress through the sinus-lining endothelium (SLE) via thoracic duct lymph into blood (21). We recently found that T- and B-cells require the S1P1 receptor for egress from peripheral lymphoid organs (Figure 2A), and that thymocytes require this receptor to egress from thymus (14). In mice, whose hematopoietic cells lacked the S1P1 receptor, S1P1-deficient T-cell precursors were able to enter the thymus, but mature single CD4 or CD8 positive, l-selectinhi thymocytes were unable to egress into blood. Further, isolated S1P1-deficient T-cells and B-cells were refractory to migrate ex vivo in response to S1P and, if adoptively transferred to wild-type mice, readily entered the peripheral lymphoid organs but were unable to egress. Accordingly, pro/pre- and immature B-cells were present at their usual frequency in the bone marrow, whereas mature B-cells that recirculate from blood to bone marrow were reduced (14).

image

Figure 2. S1P/S1P1-dependent egress of T-cells from lymph nodes: modulation by FTY720-P. (A) Naïve T-cells (Tn) regularly circulate between blood and lymphatic tissue. Tn enter lymph nodes (LN) via high endothelial venules (HEV) and egress in an S1P/S1P1-dependent step through the sinus-lining endothelium (SLE) via the efferent lymph into blood. In case of productive antigen encounter in the LN, Tn become activated (Tact) and transiently down-modulate S1P1; this renders cells unresponsive to the obligatory egress signal provided by S1P, and, as a consequence, the proliferating cells remain in the LN. At the end of the proliferation phase, Tact up-regulate S1P1 and egress from LN in an S1P/S1P1-dependent step. (B) FTY720, after phosphorylation, acts as ‘super agonist’ at S1P1 on Tn and Tact, thereby inducing aberrant internalization of the receptor. This renders all T-cells unresponsive to sphingosine 1-phosphate (S1P), depriving them from the obligatory egress signal provided by S1P. As a result, all Tn and Tact are ‘trapped’ in LN, being unable to recirculate to peripheral tissues. Similarly, FTY720 down-modulates S1P1 on thymocytes and B-cells, retaining them in thymus and LN, respectively (not shown).

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The physiological role of S1P1 and its natural ligand S1P during the course of an immune response was analyzed in ovalbumin-immunized, T-cell receptor-transgenic mice (14). One day after antigen exposure, the specific LN T-cells had lost their responsiveness to S1P and they had down-regulated S1P1 expression 100-fold. Three days after immunization, many recently divided antigen-specific T-cells had appeared in circulation, and at this time the activated draining LN cells exhibited restored S1P responsiveness and increased S1P1 receptor levels. The T-cell response to S1P in vitro was predominantly chemotactic rather than chemokinetic, as cells migrated only poorly when S1P was added without a gradient. Thus, down-regulation of S1P1 responsiveness is associated with the initial retention of activated T-cells in lymphoid organs, and reacquisition of responsiveness to an S1P gradient between blood and LN is associated with their exit (Figure 2A).

The similar effects of S1P1 deficiency and treatment with FTY720 on lymphocyte traffic suggested that active doses of FTY720 might cause functional inactivation of S1P1 on lymphocytes (Figure 2B). Indeed, mature thymocytes from FTY720-treated mice were unable to egress from thymus (14,22), and peripheral T- and B-cells failed to exit from LN (8,14). Further, the T-cells failed to migrate in response to S1P while migrating normally to the CCR7 ligand CCL21/SLC (14), demonstrating that in vivo exposure to the drug inactivates the ability of S1P1 to support T-cell chemotaxis. Experiments with S1P1-transfected cells finally showed that FTY720 treatment caused rapid internalization and degradation of the S1P1 receptor from membranes, in a manner that is different from that of the endogenous ligand S1P (14,23,24). All together these findings establish that S1P1 is essential for lymphocyte recirculation and that it regulates egress from both thymus and peripheral lymphoid organs. FTY720 treatment down-regulates S1P1, thereby creating a temporary pharmacological S1P1-null state in lymphocytes, providing an explanation for the mechanism of FTY720-induced lymphocyte sequestration.

Altered Lymphocyte Traffic and Immunity to Infection

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

FTY720 inhibited the exit of mature thymocytes and lymphocytes into blood, thereby lowering T-cell numbers in the LN, and both T- and B-cell counts in the peripheral blood (14). This pharmacodynamic state was associated with a reduction in effector T-cell numbers infiltrating grafted skin (25), heart (26) and pancreatic islets (27), islets of autoimmune-induced non-obese diabetic (NOD) mice (27,28), and the CNS of mice in models of human multiple sclerosis (29). However, the drug did not affect the functionality of T- and B-cells and their activation in response to infection. FTY720 did not impair the induction of humoral immunity and of specific cytotoxic CD8 T-lymphocytes (CTL) in mice infected with lymphocytic choriomeningitis virus (LCMV) or vesicular stomatitis virus (VSV) (6). Further, FTY720 did not suppress activation of specific CD4 T-cells in mice immunized with ovalbumin, and antigen-primed T-cells from drug-treated and control mice produced comparable amounts of interferon-γ (IFN-γ) upon restimulation by antigen (30). However, FTY720 reduced the recruitment of specific T-cells to draining LN in response to local antigen challenge (6,30). Consistent with this mechanism, FTY720 did not impair graft-vs-leukemia (GVL) reactions in the LN of mice receiving bone marrow transplants, but prevented graft-vs-host disease (GVHD) by suppressing recirculation of allo-reactive donor cells to peripheral organs (31). Further, FTY720 suppressed cellular infiltration and tissue necrosis in a murine model of viral myocarditis, whereas calcineurin inhibitors accelerated viral replication and exacerbated pathology (32). Thus, FTY720 leaves intact parts of the host-protective immunity, and it remains to be determined whether in a transplant situation this reduces the risk of lymphoma development and reactivation of latent viruses, including cytomegalovirus and hepatitis C virus.

In nonhuman primates treated with FTY720 for > 100 days, approximately 5% of peripheral blood CD4 T-cells and 30% of CD8 T-cells were refractory to depletion by the drug (33). It is likely that these cells represent long-lived effector memory T-cells (TEM) (34–36). In contrast to naïve and central memory T-cells (TCM), TEM lack the LN homing receptors CCR7 and CD62L (21,36) and reside in nonlymphoid tissues (34). Thus, TEM are not trapped by FTY720 in the LN and therefore would escape exposure to alloantigen and ignore a graft. In several models of viral and bacterial infection, large numbers of specific TEM were found in peripheral blood, small intestine lamina propria, lung, liver, kidney and peritoneal cavity (34), and these cells appear to be propagated and maintained by IL-7 and IL-15 (35). TEM expressed high levels of inflammatory chemokine receptors (21,36) and therefore could be effectively recruited to inflammatory tissues to display immediate effector function (34). In humans, TEM appeared to be long-lived, as proliferative responses to tetanus toxoid were consistently found in this subset even 10 years after vaccination (36). Thus, TEM-like cells constitute a reservoir of peripheral effector cells whose function is likely not to be affected by FTY720.

FTY720 and the Endothelium

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

FTY720 induced maximal blood lymphopenia at trough levels of approximately 10 ng/mL (37), whereas optimal efficacy in models of transplantation required at least fivefold higher concentrations. This suggested that FTY720 may promote additional therapeutically relevant effects that are unrelated to altered lymphocyte traffic. Recent studies in conditional mutant mice with specific deletion of S1P1 from EC demonstrated that this receptor is key within the endothelium to regulate embryonic blood vessel development and coverage of the vessels by vascular smooth muscle cells (VSMC) (38). This process was found to be crucial for stabilization of vessels, protection against rupture and maintenance of hemostasis. Other studies suggested a role of S1P1 and/or S1P3 for endothelial morphogenesis into capillary-like structures (39), preservation of barrier integrity (39,40) and cytoprotection (41).

We found that both S1P and FTY720-P induced translocation of vascular endothelial cadherin to the focal contact sites between EC and promoted adherens junction assembly in vitro (20,39) (Figure 3). Accordingly administration of FTY720 (20) or S1P (40) to mice blocked VEGF-induced vascular permeability for macromolecules. The comparable effects of S1P and FTY720-P on EC suggested that, unlike in lymphocytes, the relevant target receptors were not internalized by FTY720-P. The barrier-enhancing effect of FTY720 (and S1P) in vivo may help in preventing vascular leakage that is recognized as a cardinal feature of diverse and important pathobiological processes, including acute lung injury (42), atherogenesis (43), chronic allograft rejection (44), and ischemia-reperfusion (I/R) injury (45). Indeed, FTY720 prevented perivascular inflammation and graft arteriosclerosis in rodent models of heart and carotid artery transplantation (26,46), and significantly reduced I/R injury of rat livers (47).

image

Figure 3. Preservation of vascular integrity by FTY720-P. In endothelial cells (EC), FTY720-P induces translocation of vascular endothelial cadherin (VE-cadherin) and β-catenin to the focal contact sites between the cells, thereby promoting adherens junction assembly. The α-, β- and γ-catenins connect to the intracellular cortical actin ring of the cytoskeleton and this process stabilizes the endothelium and enhances endothelial barrier function. Similar effects are induced by S1P (not shown), suggesting that FTY720-P may not internalize but rather signal its target receptors in EC; the signaling may involve S1P3 and/or S1P1.

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Both FTY720-P and S1P increased EC survival under conditions of serum starvation in vitro (20,39). Very recent studies demonstrated that the cardioprotective high-density lipoprotein (HDL) functions as a carrier of S1P (41), and that HDL and S1P activate endothelial nitric oxide synthase (eNOS) and induce nitiric oxide (NO)-dependent vasorelaxation via S1P3 (41,48); NO represents a critical mediator in the health of the cardiovascular system in general (41,48), and it remains to be determined whether the cytoprotective effects of FTY720-P may relate at least in part to the induction of the eNOS/NO pathway.

FTY720 and the Regulation of Heart Rate

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

In clinical trials and in animal models, FTY720 induced a mild and transient reduction of heart rate after the initial two dosings (1–3). The effect could be antagonized by β2-receptor agonists or atropine (3), suggesting cross-talk between S1P receptor/Gαi pathways and muscarinic receptor/Gαi activation. Two recent papers proposed a role of S1P3 in the regulation of heart rate, as this receptor is dominantly expressed in rodent atrial and ventricular heart tissue (49), and FTY720 (and the structural analogs AAL151 and AFD298) reduced heart rate in wild-type but not in S1P3-deficient mice (49,50). However, the high expression of S1P1 in human atrium and ventricle (51) could indicate potential species differences regarding the relative contribution of S1P1 vs. S1P3.

Earlier studies already demonstrated that S1P receptor agonists induced a negative chronotropic effect in perfused guinea pig hearts (52) and in isolated rabbit sinoatrial node cells (53), and this coincided with activation of an Gαi-dependent, inward rectifying K+ channel (GIRK/IK.Ach) (52,54,55) that promoted membrane hyperpolarization and, as a consequence, reduced cellular excitability and pacemaker frequency (55,56). Ongoing studies with isolated guinea pig and rat atrial myocytes now confirmed that, like S1P, FTY720-P activated GIRK channels (L. Pott, Ruhr Universtity Bochum, Germany, personal communication November 2003). Interestingly, a short pre-incubation of the cells with FTY720-P rendered them unresponsive to FTY720-P but not to muscarinic (re)stimulation, and this S1P receptor-specific ‘desensitization’ most likely reflected receptor internalization and could explain the transient nature of the effect. In conclusion, stimulation of S1P receptors on atrial myocytes apparently mimics a transient activation of muscarinic receptors, a receptor class that contributes to vagally-mediated slowing of the pacemaker (54).

FTY720 and Renal Function

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

In rats, FTY720 did not cause any changes in markers of hepatocyte injury, nor did it cause a reduction in renal function. Histologic examination of liver and kidney from animals treated with high oral doses of FTY720 (5 mg/kg/day) for 3 weeks did not reveal any sclerosis, tubular changes, cellular infiltrates or fibrosis, and the hepatocyte, vascular, and biliary structures were normal (57). FTY720 given intravenously (i.v.) at doses up to 1 mg/kg did not alter renal cortical perfusion, renal artery blood flow and renal vascular resistance (57). These data suggest that FTY720 does not cause any acute adverse effects on renal or hepatic hemodynamics, nor does it cause a reduction in glomerular perfusion.

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

Current data suggest that FTY720 displays a novel mode of action that is not observed with classic immunosuppressive drugs. FTY720, after phosphorylation, acts as a high-affinity agonist at the S1P1 receptor on thymocytes and lymphocytes, thereby internalizing the receptor. This renders the cells unresponsive to the serum sphingolipid S1P, depriving them from an obligatory signal to egress from lymphoid organs. As a consequence, T- and B-cells are unable to recirculate to peripheral inflammatory tissues and graft sites. At the same time, FTY720-P mimics vasoprotective effects of the serum lipid S1P, presumably through signaling at S1P3 and/or S1P1 on EC. The available data point to therapeutically relevant effects of FTY720 on lymphocytes and vascular endothelium.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References

We thank L. Pott, Ruhr University Bochum, Germany, for sharing unpublished data. Further, we would like to thank R. Albert, Novartis, for synthesis of FTY720 and analogs, and P. Burtin, S. Fornairon, R. Schmouder, S. Aradhye and P. Heining for updates on FTY720 clinical trials and preclinical safety. We apologize that, given the restricted reference number in this article, only a small selection out of the large number of excellent publications in the field could be cited.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. G Protein-Coupled Receptors for Sphingosine 1-Phosphate: The Molecular Targets of Phosphorylated FTY720
  5. FTY720-P Internalizes S1P1 on Lymphocytes and Abrogates S1P/S1P1-Dependent Egress from Lymphoid Organs
  6. Altered Lymphocyte Traffic and Immunity to Infection
  7. FTY720 and the Endothelium
  8. FTY720 and the Regulation of Heart Rate
  9. FTY720 and Renal Function
  10. Conclusions
  11. Acknowledgments
  12. References
  • 1
    Brinkmann V, Pinschewer DD, Feng L, Chen S. FTY720: Altered lymphocyte traffic results in allograft protection. Transplantation 2001; 72: 764769.
  • 2
    Brinkmann V, Lynch KR. FTY720: targeting G-protein-coupled receptors for sphingosine 1-phosphate in transplantation and autoimmunity. Curr Opin Immunol 2002; 14: 569575.
  • 3
    Tedesco-Silva H, Mourad G, Kahan BD et al.. FTY720, a novel immunomodulator – efficacy and safety results from the first Phase 2a study in de novo renal transplantation. Transplantation 2004.
  • 4
    Adachi K, Kohara T, Nakao N et al.. Design, synthesis and structure-activity relationships of 2-substituted 2-amino- 1,3-propanediols: Discovery of a novel immunosuppressant, FTY720. Bioorg Med Chem Lett 1995; 5: 853856.
  • 5
    Chen JK, Lane WS, Schreiber S. The identification of myriocin-binding proteins. Chem Biol 1999; 6: 221235.
  • 6
    Pinschewer DD, Ochsenbein AF, Odermatt B, Brinkmann V, Hengartner H, Zinkernagel RM. FTY720 immunosuppression impairs effector T-cell peripheral homing without affecting induction, expansion, and memory. J Immunol 2000; 164: 57615770.
  • 7
    Brinkmann V, Pinschewer D, Chiba K, Feng L. FTY720: a novel transplantation drug that modulates lymphocyte traffic rather than activation. Trends Pharmacol Sci 2000; 21: 4952.
  • 8
    Chiba K, Yanagawa Y, Masubuchi Y et al.. FTY720, a novel immunosuppressant, induces sequestration of circulating mature lymphocytes by acceleration of lymphocyte homing in rats. I. FTY720 selectively decreases the number of circulating mature lymphocytes by acceleration of lymphocyte homing. J Immunol 1998; 160: 50375044.
  • 9
    Bai Y, Liu J, Wang Y et al.. 1-selectin-dependent lymphoid occupancy is required to induce alloantigen-specific tolerance. J Immunol 2002; 168: 15791589.
  • 10
    Henning G, Ohl L, Junt T et al.. CC Chemokine receptor 7-dependent and -independent pathways for lymphocyte homing: modulation by FTY720. J Exp Med 2001; 194: 18751881.
  • 11
    Muller G, Reiterer P, Hopken UE, Golfier S, Lipp M. Role of homeostatic chemokine and sphingosine-1-phosphate receptors in the organization of lymphoid tissue. Ann N Y Acad Sci 2003; 987: 107116.
  • 12
    Brinkmann V, Davis MD, Heise CE et al.. The immune modulator FTY720 targets sphingosine 1-phosphate receptors. J Biol Chem 2002; 277: 2145321457.
  • 13
    Mandala S, Hajdu R, Bergstrom J et al.. Alteration of lymphocyte trafficking by sphingosine 1-phosphate receptor agonists. Science 2002; 296: 346349.
  • 14
    Matloubian M, Lo C, Cinnamon G et al.. Lymphocyte egress from thymus and peripheral lymphoid organs is sphingosine 1-phosphate receptor-1 dependent. Nature 2004; 427: 355360.
  • 15
    Kimura T, Sato K, Kuwabara A 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: 3178031785.
  • 16
    English D, Welch Z, Kovala AT et al.. Sphingosine 1-phosphate released from platelets during clotting accounts for the potent endothelial cell chemotactic activity of blood serum and provides a novel link between hemostasis and angiogenesis. FASEB J 2000; 14: 22552265.
  • 17
    Prieschl EE, Csonga R, Novotny V, Kikuchi GE, Baumruker T. The balance between sphingosine and sphingosine-1-phosphate is decisive for mast-cell activation after Fc epsilon receptor I triggering. J Exp Med 1999; 190: 18.
  • 18
    Ancellin N, Colmont C, Su J et al.. Extracellular export of sphingosine kinase-1 enzyme. Sphingosine 1-phosphate generation and the induction of angiogenic vascular maturation. J Biol Chem 2002; 277: 66676675.
  • 19
    Hla T, Lee MJ, Ancellin N, Paik JH, Kluk MJ. Lysophospholipids-receptor revelations. Science 2001; 294: 18751878.
  • 20
    Sanchez T, Estrada-Hernandez T, Paik JH et al.. Phosphorylation and action of the immunomodulator FTY720 inhibits vascular endothelial cell growth factor-induced vascular permeability. J Biol Chem 2003; 278: 4728147290.
  • 21
    Sallusto F, Lanzavecchia A. Understanding dendritic cell and T-lymphocyte traffic through the analysis of chemokine receptor expression. Immunol Rev 2000; 177: 134140.
  • 22
    Yagi H, Kamba R, Chiba K et al.. Immunosuppressant FTY720 inhibits thymocyte emigration. Eur J Immunol 2000; 30: 14351444.
  • 23
    Graeler MH, Goezl EJ. The immunosuppressant FTY720 downregulates sphingosine 1-phosphate G protein-coupled receptors. FASEB J 2004 (Epub ahead of print).
  • 24
    Liu CH, Thangada S, Lee MJ, Van Brocklyn JR, Spiegel S, Hla T. Ligand-induced trafficking of the sphingosine-1-phosphate receptor EDG-1. Mol Biol Cell 1999; 10: 11791190.
  • 25
    Yanagawa Y, Sugahara K, Kataoka H, Kawaguchi T, Masubuchi Y, Chiba K. FTY720, a novel immunosuppressant possessing unique mechanisms. II. FTY720 prolongs skin allograft survival by decreasing T-cell infiltration into grafts but not cytokine production in vivo. J Immunol 1998; 160: 54935499.
  • 26
    Hwang MW, Matsumori A, Furukawa Y et al.. FTY720, a new immunosuppressant, promotes long-term graft survival and inhibits the progression of graft coronary artery disease in a murine model of cardiac transplantation. Circulation 1999; 100: 13221329.
  • 27
    Fu F, Hu S, Deleo J et al.. Long-term islet graft survival in STZ and autoimmune induced diabetes models by immunosuppressive and potential insulinotropic agent FTY720. Transplantation 2002; 73: 14251430.
  • 28
    Yang Z, Chen M, Fialkow LB et al.. The immune modulator FTY720 prevents autoimmune diabetes in nonobese diabetic mice. Clin Immunol 2003; 107: 3035.
  • 29
    Fujino M, Funeshima N, Kitazawa Y et al.. Amelioration of experimental autoimmune encephalomyelitis in Lewis rats by FTY720 treatment. J Pharmacol Exp Ther 2003; 305: 7077.
  • 30
    Xie JH, Nomura N, Koprak SL, Quackenbush EJ, Forrest MJ, Rosen H. Sphingosine-1-phosphate receptor agonist impairs the efficiency of the local immune response by altering trafficking of naive and antigen-activated CD4+ T-cells. J Immunol 2003; 170: 36623670.
  • 31
    Kim YM, Sachs T, Asavaroengchai W, Bronson R, Sykes M. Graft-versus-host disease can be separated from graft-versus-lymphoma effects by control of lymphocyte trafficking with FTY720. J Clin Invest 2003; 111: 659669.
  • 32
    Miyamoto T, Matsumori A, Hwang MW, Nishio R, Ito H, Sasayama S. Therapeutic effects of FTY720, a new immunosuppressive agent, in a murine model of acute viral myocarditis. J Am Coll Cardiol 2001; 37: 17131718.
  • 33
    Schuurman HJ, Menninger K, Audet M et al.. Oral efficacy of the new immunomodulator FTY720 in cynomolgus monkey kidney allotransplantation, given alone or in combination with cyclosporine or RAD. Transplantation 2002; 74: 951960.
  • 34
    Masopust D, Vezys V, Marzo AL, Lefrancois L. Preferential localization of effector memory cells in nonlymphoid tissue. Science 2001; 291: 24132417.
  • 35
    Schluns KS, Lefrancois L. Cytokine control of memory T-cell development and survival. Nat Rev Immunol 2003; 3: 269279.
  • 36
    Sallusto F, Lenig D, Forster R, Lipp M, Lanzavecchia A. Two subsets of memory T lymphocytes with distinct homing potentials and effector functions. Nature 1999; 401: 708712.
  • 37
    Nikolova Z, Hof A, Baumlin Y, Hof RP. Efficacy of SDZ RAD compared with CsA monotherapy and combined RAD/FTY720 treatment in a murine cardiac allotransplantation model. Transpl Immunol 2001; 9: 4349.
  • 38
    Allende ML, Yamashita T, Proia RL. G-protein coupled receptor S1P1 acts within endothelial cells to regulate vascular maturation. Blood 2003; 102: 36653667.
  • 39
    Lee MJ, Thangada S, Claffey KP et al.. Vascular endothelial cell adherens junction assembly and morphogenesis induced by sphingosine-1-phosphate. Cell 1999; 99: 301312.
  • 40
    Schaphorst KL, Chiang E, Jacobs KN et al.. Role of sphingosine-1 phosphate in the enhancement of endothelial barrier integrity by platelet-released products. Am J Physiol Lung Cell Mol Physiol 2003; 285: 258267.
  • 41
    Nofer JR, Van der Giet M, Toelle M et al.. HDL induces NO-dependent vasorelaxation via the lysophospholipid receptor S1P3: role of HDL-associated lysophospholipids. J Clin Invest 2004; 113: 569581.
  • 42
    Dudek SM, Garcia JG. Cytoskeletal regulation of pulmonary vascular permeability. J Appl Physiol 2001; 91: 14871500.
  • 43
    Bassenge E. Endothelial function in different organs. Prog Cardiovasc Dis 1996; 39: 209228.
  • 44
    Labarrere CA, Nelson DR, Park JW. Pathologic markers of allograft arteriopathy: insight into the pathophysiology of cardiac allograft chronic rejection. Curr Opin Cardiol 2001; 16: 110117.
  • 45
    Cooper D, Stokes KY, Tailor A, Granger DN. Oxidative stress promotes blood cell–endothelial cell interactions in the microcirculation. Cardiovasc Toxicol 2002; 2: 165180.
  • 46
    Nikolova Z, Hof A, Rudin M, Baumlin Y, Kraus G, Hof RP. Prevention of graft vessel disease by combined FTY720 and Cyclosporin A treatment in the DA to Lewis rat carotid artery transplantation model. Transplantation 2000; 69: 25252530.
  • 47
    Anselmo DM, Amersi FF, Shen XD et al.. FTY720 pretreatment reduces warm hepatic ischemia reperfusion injury through inhibition of T-lymphocyte infiltration. Am J Transplant 2002; 2: 843849.
  • 48
    Dantas AP, Igarashi J, Michel T. Sphingosine 1-phosphate and control of vascular tone. Am J Physiol Heart Circ Physiol 2003; 284: 20452052.
  • 49
    Forrest M, Sun SY, Hajdu R et al.. Immune cell regulation and cardiovascular effects of sphingosine 1-phosphate receptor agonists in rodents are mediated via distinct receptor sub-types. J Pharmacol Exp Ther 2004 (Epub ahead of print).
  • 50
    Sanna MG, Liao J, Jo E et al.. Distinct S1P receptor subtypes S1P1 and S1P3 respectively regulate lymphocyte recirculation and heart rate. J Biol Chem 2004 (Epub ahead of print).
  • 51
    Mazurais D, Robert P, Gout B, Berrebi-Bertrand I, Laville MP, Calmels T. Cell type-specific localization of human cardiac S1P receptors. J Histochem Cytochem 2002; 50: 661670.
  • 52
    Liliom K, Sun G, Bunemann M et al.. Sphingosylphosphocholine is a naturally occurring lipid mediator in blood plasma: a possible role in regulating cardiac function via sphingolipid receptors. Biochem J 2001; 355: 189197.
  • 53
    Guo J, MacDonell KL, Giles WR. Effects of sphingosine 1-phosphate on pacemaker activity in rabbit sino-atrial node cells. Pflugers Arch 1999; 438: 642648.
  • 54
    Bunemann M, Brandts Bzu Heringdorf DM, Van Koppen CJ, Jakobs KH, Pott L. Activation of muscarinic K+ current in guinea-pig atrial myocytes by sphingosine-1-phosphate. J Physiol 1995; 489: 701777.
  • 55
    Yamada M. The role of muscarinic K(+) channels in the negative chronotropic effect of a muscarinic agonist. J Pharmacol Exp Ther 2002; 300: 681687.
  • 56
    Jan LY, Jan YN. Heartfelt crosstalk: desensitization of the GIRK current. Nat Cell Biol 2000; 2: 165167.
  • 57
    Tawadrous MN, Mabuchi A, Zimmermann A, Wheatley AM. Effects of immunosuppressant FTY720 on renal and hepatic hemodynamics in the rat. Transplantation 2002; 74: 602610.