Efficacy of SDZ RAD compared with CsA monotherapyand combined Rad/FTY720 treatment in a murine cardiac allotransplantation model.

OBJECTIVE: The macrolide immunosuppressant RAD and the immunomodulator FTY720 have distinct mechanisms ofaction. We investigated the efficacy of RAD (everolimus, certican) alone or in combination with FTY720 on graft survival (GS)and histology in comparison with CsA, using mouse strains with strong MHC disparity. METHODS: Heterotopic cardiac grafting was performed using the C57B1/6 to C3H strain combination. Osmotic mini-pumps filled with CsA or RAD were implanted subcutaneously. IFTY720 was administered as a single daily dose by gavage. Peripheral lymphocyte count (PLC) was determined at 1, 4 and 8 weeks or on the day of sacrifice. Body weight was recorded on the day of surgery and weekly. Grafts were histologically evaluated. MAIN FINDINGS: In placebo-treated mice the allografts were rejected after 7 days. Monotherapy with 10 and 30 mg/kg/day CsA achieved 10 and 22.5 days median survival time (MST), while 0.1, 0.3, 1 and 3 mg/kg/day RAD resulted in 10.5, 20, > 56 and > 56 days MST, respectively. FTY720 lowered the PLC significantly, while the lower CsA dose and RAD did not influence the PLC. Adding FTY720 to the 0.6 mg/kg/day dose of RAD extended GS modestly but reduced significantly the perivascular infiltration and endothelialitis in the grafts compared with RAD monotherapy. CONCLUSIONS: Underthe conditions of the present experiment RAD was more potent than CsA in extending the GS. Combining FTY720 and RADwas well tolerated with respect to weight gain and lack of clinically detectable infections in the mice. The 2-drug regimens suppressed the inflammatory allo-response better than RAD monotherapy.     

The peripheral lymphocyte count predicts graft survival in DA to Lewis heterotopic heart transplantation treated with FTY720 and SDZ RAD

OBJECTIVE: The new immunomodulator 2-amino-2-(2-[4-octylphenyl]ethyl)-1,3-propanediol hydrochloride (FTY720) lowers the peripheral lymphocyte count (PLC) by inducing migration of circulating lymphocytes to secondary lymphoid organs. This effect is dose-dependent at low (up to 0.1 mg/kg per day) doses in rats. We investigated the correlation between PLC and the later rejection, when FTY720 was combined with RAD. METHODS: Heterotopic cardiac grafting was performed using the DA-Lewis strain combination. FTY720 and RAD were administered as single daily doses by gavage alone and in combination starting 3 days before to 28 days after transplantation. Graft survival was monitored daily by palpation. PLC was determined at 1 and 4 weeks, body weight (BW) weekly. Histologic evaluation of grafted hearts was performed after rejection. MAIN FINDINGS: FTY720 at doses of 0.03, 0.1 and 0.3 mg/kg per day prolonged graft survival dose-dependently from 6 (placebo) to 7, 9.5 and 15 days median survival time (MST). RAD at doses of 0.3, 1 and 3 mg/kg per day delayed rejection to 8.5, 18 and 37.5 days MST. Very small FTY720 doses added to the lower RAD doses were effective in maintaining grafts throughout the treatment period and with normal weight gain, as opposed to regimens with 1 mg/kg or more per day RAD, which resulted in delayed weight gain. FTY720 lowered the PLC significantly and dose-dependently. The PLC correlated well with graft survival [Spearman rank correlation (n = 30, rs = -0.75)]. CONCLUSIONS: Fully effective FTY720 + RAD combination regimens caused no side effects with respect to the rats' general well-being or weight gain and were better tolerated than equiactive RAD monotherapy, suggesting a broader therapeutic window for the combinations. Under the experimental conditions, the PLC decrease showed an interesting correlation with the anti-rejection effects in these two-drug regimens. Thus, in rats the PLC is helpful for monitoring the biological activity of FTY720 at low doses (< 0.1 mg/kg per day), i.e. in the range of the steep part of its dose-response relationship.     

Prevention of graft vessel disease by combined FTY720/cyclosporine. A treatment in a rat carotid artery transplantation model

BACKGROUND: Graft vessel disease (GVD) is an important problem often responsible for late graft loss. The effects of FTY720, an immunomodulator with a novel mechanism of action were investigated in combination with cyclosporine A (CsA) in a carotid artery allograft model. METHODS: A segment of the carotid artery of Lewis rats was replaced by a DA allograft. Seven groups of eight rats were treated for 8 weeks with vehicle (P), CsA 0.3 (C0.3), 1 (C1) or 3 (C3) mg x kg(-1).day(-1) or a combination of CsA 1 with FTY 0.01 (C1F0.01), 0.03 (C1F0.03), and 0.1 (C1F0.1) mg x kg(-1).day(-1). Lumen area was estimated by magnetic resonance imaging, peripheral lymphocyte count and drug concentrations were determined at 1 and 8 weeks. Neointima, media, and lumen area were measured morphometrically. Intimal and adventitial infiltration of mononuclear cells, and medial smooth muscle cells number was assessed using a score. RESULTS: FTY720 did not influence CsA blood concentrations. FTY720 but not CsA decreased the PLC dose dependently. Magnetic resonance imaging revealed that treatment groups have larger lumen size than group P. Histological and morphometric evaluation showed that all aspects of GVD were dose dependently suppressed by treatment and lumen narrowing was prevented. CONCLUSIONS: CsA, at clinically relevant blood levels, suppressed GVD only partly. The addition of FTY720 was well tolerated and completely suppressed GVD development. In vivo lumen size did not correlate with the histologically estimated neointimal thickness.     

Combined FTY720/cyclosporine treatment promotes graft survival and lowers the peripheral lymphocyte count in a murine cardiac allotransplantation model

BACKGROUND: FTY720 lowers the peripheral lymphocyte count (PLC) by accelerating the migration of circulating lymphocytes to secondary lymphoid organs. We investigated the efficacy of combined FTY720+cyclosporine (CsA) treatment versus monotherapy on prolonging graft survival and on lowering the PLC. METHODS: BALB/c hearts were heterotopically grafted in C3H mice. FTY720 was administered alone or in combination with CsA. PLC and body weight were determined on day 7, day 28, or the day of rejection. RESULTS: Combining FTY720 with CsA prolonged, dose-dependently and significantly, the allograft survival. FTY720, but not CsA, lowered the PLC dose-dependently. The granulocyte count was not reduced in any group. FTY720 concentrations were not influenced by the CsA co-administration. CONCLUSIONS: Combined FTY720 and CsA treatment was well tolerated, promoted graft survival, and suppressed the inflammatory allo-response. The PLC lowering correlated well with the antirejection effects in the two-drug regimens, suggesting that the PLC might guide FTY720 therapy at low doses.     

Use of sphingosine-1-phosphate 1 receptor agonist, KRP-203, in combination with a subtherapeutic dose of cyclosporine A for rat renal transplantation

BACKGROUND: We demonstrate the long-term effectiveness of KRP-203 treatment in combination with a subtherapeutic dose of cyclosporine A (CsA) on rat renal allografts. METHODS: We tested the effect of KRP-203 in combination with CsA using a rat skin allograft model. The Pharmacokinetic interaction between CsA and KRP-203 was evaluated. The selectivity of KRP-203 for sphingosine-1-phosphate (S1P)1 and S1P3 receptors were investigated in vitro. Heart rate alteration following bolus injection of phosphorylated KRP-203 (KRP-203-P) or FTY720 (FTY720-P) was also monitored in rats. Finally, the long-term effectiveness of KRP-203 in conjunction with a low dose of CsA was investigated in a rat renal transplantation model. RESULTS: Administration of KRP-203 with CsA prolonged skin allograft survival. KRP-203 and CsA had no effect on the pharmacokinetics of the other. While FTY720-P activated both S1P1 and S1P3 receptors, KRP-203-P selectively activated S1P1, but not the S1P3 receptor (EC50:>1000 nM). Compared to FTY720-P, a tenfold higher dose of KRP-203-P was necessary to induce transient bradycardia. With a low dose of CsA (1 mg/kg/day), KRP-203 (0.3 mg/kg/day) significantly prolonged renal allograft survival (P<0.05, survival time: 9.8 days (CsA) vs. >27.4 days (CsA+KRP)). Although a higher dose of CsA (3 mg/kg/day) alone kept recipients alive, this caused severe renal graft dysfunction. Use of KRP-203 (3 mg/kg/day) in conjunction with CsA markedly improved graft function (P<0.05, creatinine clearance: 0.41+/-0.25 ml/min [CsA] vs. 1.15+/-0.16 ml/min [CsA+KRP]). CONCLUSIONS: The selectivity of KRP-203 for S1P1 reduces the risk of bradycardia, and the combination therapy of KRP-203 with CsA represents a safe and effective strategy for use in renal transplantation.     

A new immunosuppressant, FTY720, in canine kidney transplantation: effect of single-drug, induction and combination treatments

Three different types of treatment were conducted to clarify the properties of a novel immunomodulator, FTY720, in canine kidney allograft models. Survival, biochemical and hematological tests, pharmacokinetics, and histopathology of grafts and extra-renal organs were analyzed. Accompanying a remarkable reduction in circulating lymphocytes, single-drug treatment of FTY720, ranging from 0.05 to 10 mg/kg, exhibited significant prolongation of graft survival without a dose-dependent effect. Short-course induction with FTY720 at 5 mg/kg per day exhibited similar anti-rejection effects as did single-drug treatment but no advantage in rescuing ongoing rejection. In combination with cyclosporine (CsA; 5 mg/kg) or tacrolimus (FK; 0.5 mg/kg), FTY720 had an additive effect. Trough blood concentrations of FTY720 were linearly correlated with dose. No animal showed critical adverse effects at any point. FTY720 holds promise as a candidate in a new category of drugs that can be combined with conventional agents for induction and maintenance immunosuppression in clinical organ transplantation.     

Prolongation of canine liver allograft survival by a novel immunosuppressant, FTY720: effect of monotherapy and combined treatment with conventional drugs

BACKGROUND: The immunosuppressive effect and other properties of a novel immunosuppressant, FTY720, have been studied mostly in the experimental transplantation of various extrahepatic organs. In this experiment, we evaluated the antirejection potency and adverse effects of this agent on liver grafts using a canine liver transplantation model. METHODS: Forty-eight orthotopic liver transplantations were performed by the standard technique under a veno-venous bypass. Liver recipients were divided into two studies: a single-dose study with FTY720 at various doses and a combined dose study with conventional immunosuppressants (cyclosporine or tacrolimus) alone and combined with FTY720. Survival, biochemical and hematological tests, blood levels of immunosuppressants, and postmortem histology were determined. RESULTS: The median survival of untreated control animals was 9 days, whereas treatment with FTY720 at a dose of 0.1 mg/kg/day prolonged graft survival to 49.5 days. FTY720 at 1 mg/kg/day showed a slight but insignificant prolongation to 16 days, but when the dose was increased to 5 mg/kg/day, the graft was rejected at 10 days. The combination of FTY720, 0.1 mg/kg/day, with a subtherapeutic dose of cyclosporine, 5 mg/kg/ day, prolonged median animal survival from 40 days with cyclosporine alone to 74 days. A combination of FTY720 (0.1 mg/kg/day) with tacrolimus (0.5 mg/kg/ day) compromised animal survival, reducing survival from 83.5 days with tacrolimus alone to 30.5 days due to infectious complication and emaciation by overimmunosuppression. No evident drug-induced side effects were observed. CONCLUSIONS: FTY720 has a potent immunosuppressive effect when used alone at 0.1 mg/kg/day in canine liver transplantation. FTY720 is a promising candidate for future clinical application in orthotopic liver transplantation.     

FTY720,40-氧-(2-羟乙基)-雷帕霉素和环孢素A延长小鼠心脏移植物存活时间的对比研究

目的 FTY720和40-氧-(2-羟乙基)-雷帕霉素(RAD)是两种新型免疫抑制剂。为评估这两种药物的效果,我们以小鼠心脏移植为模型,对比观察了这两种药物和环孢素A(CsA)对移植物存活时间的影响。方法 供体为BALB/C小鼠,受体为C57BL/6小鼠,受鼠随机分为4组,每组6只:A组空白对照;B组每日管饲CsA 10 mg/kg体重;C组每日管饲RAD 3 mg/kg体重;D组每日管饲FTY 3 mg/kg体重。各服药组均由移植当日开始喂药,至移植心停跳或术后14 d停药。结果 各组的存活天数分别为:A组6、7、8、8、9、9;B组9、9、10、11、12;C组10、12、13、13、14;D组10、12、16、16、17、18。B、C组各有1例带心死亡。所有移植心都出现程度不同的急性排斥反应征象。结论 单独使用RAD或FTY可显著延长小鼠心脏移植物的存活时间。在各所选剂量上,CsA和RAD差异无显著性(P>0.05),FTY的效果明显优于CsA和RAD。FTY和RAD是较有前途的新型免疫抑制剂。     

FTY720, an immunosuppressant that alters lymphocyte trafficking,abrogates chronic rejection in combination with cyclosporine A

BACKGROUND: Chronic rejection remains the leading cause of failure after transplantation (Tx). FTY720, a new immunosuppressant altering lymphocyte trafficking, is effective against acute rejection, but its activity against chronic rejection is not known. METHODS: A valid model of chronic rejection was produced. Heart transplantation (HTx) was performed using fully mismatched RA (RT1p) and PVG (RT1c) rats. Administration of donor-specific blood transfusion 12 days before HTx prolongs graft survival, but features of chronic rejection including intimal hyperplasia and vascular obliteration (VO) develop with time only in allogeneic Tx. This is therefore a valid model of chronic rejection. VO was assessed on post-Tx day 90 in six groups differing according to the maintenance immunosuppressive regimen administered. group 1, donor-specific blood transfusion only and no other treatment; group 2, FTY720 (0.3 mg/kg/day orally) for 90 days; group 3, cyclosporine A (CsA) (1 mg/kg/day orally) for 90 days; group 4, combined administration of FTY720 and CsA for 90 days; group 5, transient administration of combined FTY720 and CsA for 7 days; and group 6, syngeneic HTx (RA to RA). Graft infiltrate, endothelial immunoglobulin (Ig) G deposition, and complement binding were also examined on post-Tx day 90. RESULTS: In control group 1, severe VO was observed, compared with syngeneic HTx (group 6). Monotherapy with FTY720 (group 2) or with CsA (group 3) significantly but partially reduced VO. On the contrary, combined administration of FTY720 and CsA (group 4) abrogated VO. A 1-week treatment with combined FTY720 and CsA (group 5) reduced VO but only partially. In group 1, arteriosclerosis was accompanied by graft infiltrate, endothelial IgG deposition, and complement binding. In groups 2, 3, and 5, graft infiltrating scores were partially decreased compared with group 1 but remained higher than in syngeneic controls; endothelial IgG deposition and complement binding were still present. In group 4, continuous administration of combined FTY720 and CsA reduced graft infiltrate to the level of syngeneic control and abrogated both endothelial IgG deposition and complement binding. CONCLUSIONS: Maintenance treatment with either FTY720 or CsA monotherapy partially prevents chronic rejection; short-term treatment with combined FTY720 and CsA reduces chronic rejection only partially; and continuous treatment with combined FTY720 and CsA abrogates chronic rejection, and this is accompanied by dramatic reduction of graft infiltrating cells, endothelial IgG deposition, and complement binding. Prevention of chronic rejection by maintenance treatment with FTY720 and CsA represents indirect evidence that normal lymphocyte trafficking and function are mandatory for development of chronic rejection.     

Oral efficacy of the new immunomodulator FTY720 in cynomolgus monkey kidney allotransplantation,given alone or in combination with cyclosporine or RAD

BACKGROUND: FTY720 is a novel immunomodulator with a unique mechanism of action, i.e. chemokine-dependent lymphocyte homing into secondary lymphoid organs associated with profound lymphocyte depletion in blood. We investigated its efficacy, either FTY720 alone or together with cyclosporine or the rapamycin derivative rapamycin derivative (RAD), in cynomolgus monkey kidney allotransplantation. METHODS: Life-supporting allotransplantation was performed in bilaterally nephrectomized hosts. Compounds were given once daily by oral gavage. Monitoring was done by serum creatinine and urea, and rejection was concluded when values exceeded 500 micromol/L and 50 mmol/L, respectively (5-6 times the upper limit of reference values). Rejection was confirmed by graft histology. The termination point was set to 100 days after transplantation. In addition, animals were monitored for 24 hr drug concentrations and thorough inspection of potential adverse side effects. RESULTS: FTY720 given alone at 3.0 mg/kg per day prolonged rejection-free survival (33-85 days, mean 24 hr concentration between 54 and 66 ng/mL [n=3]), but it was not efficacious at a 0.3 mg/kg per day dose. For cyclosporine alone, 30 mg/kg per day during maintenance was efficacious (average concentration above 100 ng/mL, historical data from our group), and for RAD alone 0.75 mg/kg per day (concentration above 10 ng/mL). Efficacious FTY720-cyclosporine-A (CsA) or FTY720-RAD combinations were established using 0.1-0.3 mg/kg per day FTY720, 10-30 mg/kg per day cyclosporine, and/or 0.25-0.50 mg/kg per day RAD. Compared with single-compound treatment, FTY720 effective doses and 24 hr trough concentrations were at least tenfold lower in combination treatment and those of cyclosporine and RAD about twofold lower, indicative of effective synergy between the compounds. Already at the lowest FTY720 dose tested (0.03 mg/kg per day), there was a profound lymphocyte depletion down to about 30% of pretransplant values, which further increased at the highest dose (3.0 mg/kg per day, to about 14% of pretransplant values). Lymphocyte depletion was reflected by a decrease in T and B subpopulations. CONCLUSION: FTY720 is an effective immunosuppressant in prevention of acute kidney allograft rejection in cynomolgus monkeys and synergizes with cyclosporine and/or RAD in yielding rejection-free allograft survival.     

Effect of FTY720 on immunoregulation in concordant xenotransplantation

Abstract The present study was designed to analyze the immunosuppressive activity of FTY720 in concordant xenotransplantation. When T and B lymphocytes of human peripheral blood were incubated with FTY720, the number of viable cells decreased in a dose-dependent manner at doses higher than 4×10^-5 M. DNA fragmentation was observed at doses higher than 4×10 ^-5 M in B cell-rich fractions. These data demonstrate that FTY720 is cytotoxic to B lymphocytes as well as T lymphocytes and apoptosis may play an important role in this cytotoxicity. Golden Syrian hamsters were the donors and Lewis rats the recipients of skin grafts. The recipients were divided into the following four groups; (1) untreated recipients, (2) FTY720 (5mg/kg per day) was administered orally for 8 days (days -1–6), (3) FK 506 (1 mg/kg per day) was injected i. m. for 7 days (days 0–6), and (4) FK506 (1 mg/kg per day) was injected i.m. for 7 days (days 0–6) and FTY720 (5 mg/kg per day) was administered orally for 8 days (days-1–6). The mean graft survival times in groups 1–4 were.7 ± 0.52 days ( n = 6), 12.0 ± 0.71 days ( n = 6), 13.2 ± 1.6 days ( n = 6), and 37.7 ± 4.3 days ( n = 6), respectively. There was a significant difference in the mean survival time between groups one and four. Combined therapy with FTY720 and FK506 is a useful tool for immunoregulation in xenotransplantation.     

FTY720 treatment prolongs skin graft survival in a completely incompatible strain combination

FTY720 has shown potent immunomodulatory activity in a variety of animal organ transplant models. However, the in vivo immunosuppressive mechanism of FTY720 is still not fully understood. It has been suggested that the marked decrease in the number of peripheral blood lymphocytes during FTY720 administration could be responsible for its immunosuppressive effects. Our aims were: (1) to study the effects of FTY720 treatment on skin graft survival using a fully mismatched strain combination and (2) to evaluate lymphocyte numbers in different sites at 5 days after skin transplant. C57BL/6 mice and BALB/c mice were the donors and recipients respectively. BALB/c mice received FTY720 (1 mg/kg/d) orally for 4 consecutive days. Drug administration started 1 day before skin transplants. A small segment of tail skin was affixed on the right dorsal side of the mouse via sutures. The administration of FTY720 (4 mg/kg) prolonged skin graft survival from 12.6 +/- 2.2 days (no treatment) to 16.6 +/- 4.2 days. The histologic findings of rejection were similar for all groups. Five days after transplant, lymphocyte numbers were significantly increased in lymph nodes compared with nontransplanted or isogenic graft mice. FTY720 decreased lymphocyte numbers only in the spleen. In conclusion, FTY720 prolonged skin graft survival in a fully mismatched strain combination when administered for 4 days (day -1 to day +2) at a dose of 1 mg/kg/d. The decreased number of lymphocytes in the spleen suggests that the spleen may be a target of FTY720 activity, during the early posttransplant period.     

Immunosuppressive activity of FTY720, sphingosine 1-phosphate receptor agonist: I. Prevention of allograft rejection in rats and dogs by FTY720 and FTY720-phosphate

FTY720, a new class of immunomodulator, induces lymphopenia by sequestration of circulating lymphocytes into secondary lymphoid tissues. FTY720 at 0.1 to 1 mg/kg significantly prolonged the allograft survival in a dose-dependent manner and showed a marked synergistic effect in combination with cyclosporine (CsA) in rat skin and cardiac allograft models. In addition, the canine renal allograft survival was significantly prolonged by combination therapy with FTY720 at 0.03 to 1 mg/kg and CsA at 10 mg/kg as compared with monotherapy of FTY720 or CsA. By contrast, the combination therapy with CsA and azathioprine or CsA and mycophenolate mofetil resulted in only an additive effect in rat skin allograft. When FTY720 was administered to rats, FTY720 was metabolized by omega-oxidation of the octyl side chain, and beta-oxidation subsequently, or phosphorylated by sphingosine kinase. Omega- and beta-oxidized 4 metabolities of FTY720 at 10 mg/kg i.v. showed neither lymphopenia nor immunosuppressive activity in rat skin allograft. On the other hand, (S)-enantiomer of FTY720-phosphate at 0.1 and 1 mg/kg intravenously induced a marked lymphopenia and significantly prolonged the allograft survival in the rat allotransplantation. From these results, it is suggested the lymphopenia and the immunosuppression induced by FTY720 administration is due to the agonistic activity against SIP receptors of the active metabolite, (S)-FTY720-phosphate.     

The novel immunosuppressant FTY720 induces peripheral lymphodepletion of both T- and B-cells in cynomolgus monkeys when given alone, with Cyclosporine Neoral or with RAD

OBJECTIVE: FTY720 is a new immunosuppressant active in transplantation models, which modulates lymphocyte recirculation, leading to transient peripheral lymphopenia and increased lymphocytes in lymph nodes and Peyer's patches. Here, we investigated the susceptibility of cynomolgus monkeys to FTY720 given orally either alone or in combination with two other immunosuppressants, Cyclosporin Neoral or RAD, as an introductory study to transplantation protocols. METHODS: Each of the three phases of the study comprised a 3-week treatment period with FTY720 administered daily orally at 0.3, 0.1 or 0.03 mg/kg/day, respectively, followed by a 3-week recovery. FTY720 was given as single compound during the first week and in combination with Neoral at 20 mg/kg/day p.o. or RAD at 0.5 mg/kg/day p.o. during the subsequent 2 weeks. MAIN FINDINGS: These treatment regimen were well tolerated, except for some body weight loss at high FTY720 dose (0.3 mg/kg/day). FTY720 treatment resulted in a rapid decrease of white blood cell counts which reached a plateau after 3 days. A decrease in both T- and B-lymphocyte counts by up to 80-90% was seen with FTY720 doses of 0.1 and 0.3 mg/kg/day. FTY720 blood levels, both trough levels and AUC(0-24 h), showed a linear relationship with FTY720 dose. The reduction in lymphocyte counts was not directly proportional to FTY720 blood levels. The exposure to FTY720 significantly increased upon coadministration of Neoral. This pharmacokinetic interaction was not observed for coadministration of RAD. However, the peripheral lymphodepletion was slightly increased after coadministration of RAD but not of Neoral. This may be related to the intrinsic effects of RAD on hematopoietic cells. CONCLUSIONS: FTY720 given orally was effective in terms of peripheral T- and B-lymphodepletion and was well tolerated in cynomolgus monkeys even in combination with Cyclosporine Neoral or RAD, indicating that such combination protocols could be used in allo- and xenotransplantation in this species. However, the data indicate a potentiation of FTY720 exposure by CsA coadministration and additional lymphodepletion by coadministration of FTY720 and RAD which should be carefully monitored.     

Preoperative administration of FTY720 prolonged renal allograft survival

BACKGROUND: FTY729 is an immunomodulator obtained by chemical modification of Myriocin(ISI-1) which exists in the culture filtrate of an ascomycete, Isaria sinclairii. It has been reported that postoperative administration of FTY720 prolonged survival of various kinds of transplanted organs. In the present study, we evaluated the effect of 2-day preoperative administration of FTY 720 on graft survival. MATERIALS AND METHODS: We used a rat renal transplantation model in which Wistar King Aptekman Hokkaido (WKAH, RT1K) served as the organ donor and Lewis (LEW, RTl) as the recipient. FTY720 was given to the recipients consecutively 2 days (day-2, day-1) before transplantation at the doses of 1, 3 or 5 mg/kg/day. Renal allograft survivals, hematological parameters of recipient blood and phenotypic analysis of recipient splenic cells and graft infiltrate were evaluated. RESULTS: Consecutive 2-day preoperative oral administration of FTY 720 at the doses of 1, 3 or 5 mg/kg/day significantly prolonged WKAH allograft survivals compared with those of the untreated recipients. The number of peripheral blood lymphocytes was markedly decreased in the recipients treated with FTY720 at the doses of 3 mg/kg/day or 5 mg/kg/day on the 5th postoperative day. Preoperative FTY 720 administration significantly decreased the number of CD4 positive cells and the percentage of interleukin 2 receptor (IL-2 R) positive cells infiltrating both spleen and allograft at the dose of 3 mg/kg/day or 5 mg/kg/day. CONCLUSION: FTY 720 could act as a safe and potent immunomodulator by decreasing the number of peripheral lymphocytes, especially CD4 positive cells and IL-2R positive cells when it is given to the recipient preoperatively.     

FTY720作用机制及诱导移植免疫耐受的研究

目的　进一步探讨FTY72 0作用机制及诱导移植免疫耐受的可能途径。　方法　电泳观察FTY72 0 (10 μmol/L)对体外培养的小鼠脾细胞DNA的作用。利用BALB/c(H 2d)到C57BL/6(H 2b)小鼠颈部异位心脏移植模型 ,观察FTY72 0不同给药时间对移植物存活的影响。将受体鼠分为 6组 :第 1组 (n =6)为空白对照组 ,第 2～ 6组为实验组。第 2组 (n =14 )、第 3组 (n =6)、第 4组 (n =6)每天管饲FTY72 0 (3mg/kg体重 ) ;服药时间分别为 :第 2组移植前 3日～移植后第 11日 ,第 3组移植当日～移植后 14日 ,第 4组移植前 3日～移植当日。第 5组 (n =6)和第 6组 (n =6)于移植前 3日～移植后第 11日分别管饲环孢素A(10mg/kg体重 )和 40 氧 (2 羟乙基 ) 雷帕霉素RAD(3mg/kg体重 )。第 2组中长期存活鼠中 ,部分接受了二次 (皮肤 )移植 ,部分检测了全血清IL 4和IFN γ浓度。　结果　小鼠脾细胞与FTY72 0共育后 ,DNA出现典型的凋亡改变。第 1组移植物中位存活时间 (MST)为 8d ;第 2组所有移植物存活均超过 2 7d ,1/2的移植物存活超过 10 0d ;第 3组的MST为 16 5d ;第 4组的MST为 14d ,有 1只超过 10 0d ;第 5组、第 6组的MST分别为 10d和 13d。第 2组长期存活的小鼠IL 4水平明显升高 ,IFN γ水平稳定。　结论　FTY72 0的提前使     

FTY720 inhibits TH1-mediated allogeneic humoral immune response

Phosphorylated FTY720 is an analog of Sphingosine 1 Phosphate (S1P) with immunosuppressive activity that negatively regulates the expression of S1P-Receptor 1. It also inhibits the migration of CD4 and CD8 single-positive T cells from the thymus to the periphery, sequesters peripheral blood lymphocytes in lymph nodes and Peyer's patches, and delays the exit of effector T cells toward the graft. The aim of our work was to study the effect of FTY720 on the kinetics of skin allograft rejection in a fully mismatched model; euthymic (Euthy) versus thymectomized (ATX) C57BL/6 mice (haplotype H-2(b)) recipients of BALB/c mice (haplotype H-2(d)) donor cells. The animals were injected daily with FTY720 (1 mg/kg) intraperitoneally for 2 weeks. To monitor the humoral immune response, serum samples collected at day 0 (pre-immune) and at day 23 after skin graft rejection were examined using BALB/c thymocytes as antigens in flow cytometry. To confirm the effect of FTY720 on peripheral lymphocytes, peripheral blood was analyzed by flow cytometry. Euthy and ATX FTY720-treated mice showed prolongation of skin allograft survival when compared with nontreated Euthy and ATX controls (P < .005). Unexpectedly, FTY720-treated Euthy mice showed significantly delayed graft rejection when compared to similarly treated ATX mice (P < .005). The delayed graft rejection in FTY720-treated Euthy mice correlated with a reduced content of Th1-mediated IgG(2a) and IgG(2b) antibodies when compared with FTY720-treated ATX mice (P < .05). In conclusion, FTY720 delays the kinetics of allograft rejection in a fully mismatched model by inhibiting Th1-mediated humoral immune responses. The presence of the host thymus appears to be required for this phenomenon.     

Effect of FTY720 on immunoregulation in concordant xenotransplantation

The present study was designed to analyze the immunosuppressive activity of FTY720 in concordant xenotransplantation. When T and B lymphocytes of human peripheral blood were incubated with FTY720, the number of viable cells decreased in a dose-dependent manner at doses higher than 4×10^?5 M. DNA fragmentation was observed at doses higher than 1×10^?5 M in T cell-rich fractions and at doses higher than 4×10^?5 M in B cell-rich fractions. These data demonstrate that FTY720 is cytotoxic to B lymphocytes as well as T lymphocytes and apoptosis may play an important role in this cytotoxicity. Golden Syrian hamsters were the donors and Lewis rats the recipients of skin grafts. The recipients were divided into the following four groups: (1) untreated recipients, (2) FTY720 (5 mg/kg per day) was administered orally for 8 days (days ?1–6), (3) FK506 (1 mg/kg per day) was injected i. m. for 7 days (days 0–6), and (4) FK506 (1 mg/kg per day) was injected i. m. for 7 days (days 0–6) and FTY720 (5 mg/kg per day) was administered orally for 8 days (days ?1–6). The mean graft survival times in groups 1–4 were 9.7 ± 0.52 days (n = 6), 12.0 ± 0.71 days (n = 6), 13.2 ± 1.6 days (n = 6), and 37.7 ± 4.3 days (n = 6), respectively. There was a significant difference in the mean survival time between groups one and four. Combined therapy with FTY720 and FK506 is a useful tool for immunoregulation in xenotransplantation.     

A novel immunosuppressant, FTY720, induces peripheral lymphodepletion of both T- and B cells and immunosuppression in baboons

OBJECTIVE: FTY720, a new immunosuppressant active in transplantation models, modulates lymphocyte re-circulation, leading to peripheral lymphopenia and increased lymphocytes in lymph nodes and Peyer's patches. Here, we investigated the susceptibility of baboons to FTY720 as an introductory study to transplantation protocols. METHODS: FTY720 was administered orally to Chacma baboons at 0.3 or 0.1 mg/kg/day for 3 days or at 0.03 mg/kg/day for 10 days. Haematological parameters, lymphocyte phenotype (CD3, CD4, CD8, CD20), cell apoptosis, ex vivo blood cell proliferation in response to mitogens and drug blood levels were monitored during treatment and up to 4 weeks thereafter. MAIN FINDINGS: FTY720 administered p.o. in baboons at 0.3 mg/kg/day caused a marked decrease in circulating lymphocytes within 4 h of treatment, reaching 60-80% decrease within 24-48 h. The effect of FTY720 was seen both on T- and B cells, although it was slightly more rapid/pronounced on T cells. CD4+ cells were slightly more affected than CD8+ cells. The response onset was faster and the duration longer at higher dose, but the maximal peripheral lymphodepletion achieved was similar within the dose range 0.03-0.3 mg/kg tested. Ex vivo mitogen-induced lymphoproliferation was drastically decreased after FTY720 treatment, corresponding to the reduced blood lymphocyte counts. The blood drug levels measured after FTY720 administration correlated well with the dose applied but there was a poor correlation between FTY720 blood levels and the extent of peripheral lymphodepletion, suggestive of a high tissue distribution of the drug. When compared with cynomolgus monkeys treated in the same way, baboons had a lower initial exposure and a slightly lower response 24 h after one or two doses of FTY720 0.03-0.3 mg/kg. However, the stabilized drug blood levels and peripheral lymphodepletion achieved after 7 days of FTY720 0.03 mg/kg/day were similar in both nonhuman primate species. CONCLUSIONS: FTY720 was well tolerated and was effective in terms of peripheral T- and B lymphodepletion in baboons, indicating that it could be used in protocols of allo- and xenotransplantation. The pharmacokinetic and pharmacodynamic profiles of FTY720 in baboons suggest the use of high induction doses to optimize immediate response followed by a reduced dose regimen for drug maintenance.     

Effects of immunosuppressant FTY720 on renal and hepatic hemodynamics in the rat

BACKGROUND: FTY720 is a novel immunomodulator that may provide an opportunity for a reduction in calcineurin inhibitor dosage in transplant recipients with renal/hepatic side effects. However, the effects of FTY720 on renal or hepatic hemodynamics are unknown. The aim of this study was to establish the hemodynamic and renal actions of FTY720 at therapeutically relevant dosages. METHODS: The effects of acute and repeat oral administration of FTY720 on systemic, renal, and hepatic hemodynamics were investigated in the anesthetized male Lewis rat. Renal function and renal tubular parameters were examined in animals that received repeat high dosage of FTY720. RESULTS: Seven-day oral administration of FTY720 did not cause any significant changes in markers of hepatocyte injury, nor did it cause any reduction in renal function (elevated urea and creatinine). Histological examination of liver and kidney from animals treated with repeat FTY720 for 1 or 3 weeks did not reveal any sclerosis, tubular changes, infiltrates, or fibrosis. Hepatocyte, vascular, and biliary structures were normal. Compared with the vehicle (saline), oral administration of FTY720 at dosages up to 5 mg/kg/day for 1 week did not have any significant effects on systemic, hepatic, or renal hemodynamics. Five min after intravenous FTY720 administration (1 mg/kg), mean arterial pressure (MAP) rose to 114+/-3.3% of baseline (P <0.01) before returning to the normal range within 30-45 min. Lower doses of FTY720 (0.3 and 0.5 mg/kg, i.v.) did not affect MAP. Renal cortical perfusion, renal artery blood flow, and renal vascular resistance were not altered by FTY720 at i.v. doses up to 1 mg/kg. Animals that received FTY720 (5 mg/kg/day) for 3 weeks showed a significant reduction in body weight (-4.8+/-1% of baseline at 3 weeks, P <0.001); however, weight-adjusted creatinine clearance, 24 h urine production, and urine osmolality were not different from those in control animals (0.71+/-0.1 vs. 0.74+/-0.1 ml/min/100 g, 2.63+/-0.2 vs. 3.12+/-0.2 ml/100 g, and 2003+/-33 vs. 1966+/-56 mOsm/kg, respectively). FTY720 at the same repeat oral dosage was, nevertheless, associated with a significantly lower 24 h sodium excretion and a significantly lower fractional excretion of sodium compared with those in control animals (223.4+/-35 vs. 304.5+/-50 micromol/100 g and 1.75+/-0.3 vs. 2.23+/-0.3%, respectively; P <0.05). CONCLUSIONS: Our data indicate that, at least in the short term, oral FTY720 does not cause any significant adverse effects on renal or hepatic hemodynamics, nor does it cause any reduction in glomerular perfusion and thus may provide reasonable rescue/add-on therapy in calcineurin-inhibitor treated transplant recipients. At high repeat oral dosages, however, FTY720 may alter renal handling of sodium.