大鼠小肠移植肝脏移植物抗宿主疾病中凋亡及Fas配体的表达

目的 建立大鼠小肠移植肝脏移植物抗宿主疾病（GVHD）动物模型，探讨细胞凋亡及其Fas系统与肝脏GVHD的关系。方法 选用体重为200～250g的雄性大鼠，对照组为SD-SD大鼠（n=25），实验组为Wistar-SD大鼠（n=25），行大鼠异位全小肠移植术。分别于术后第1、3、5、7、9、11天取肝组织行苏木素-伊红（HE）染色，同时检测肝功，TUNEL法检测肝脏细胞凋亡，免疫组织化学方法检测Fas及其配体（FaSL）表达。结果 两组术后肝脏功能无明显改变，光镜及电镜亦无明显凋亡性改变。实验组，TUNEL阳性细胞从术后第4天开始出现，并且随着时间的推移呈上升趋势，而对照组无明显增加。免疫组织化学结果，两组Fas在肝脏中广泛表达；而FasL只在实验组的术后第11天广泛表达，与对照组相比差异有统计学意义（P〈0．05）。结论 FasL和细胞凋亡可以被当作大鼠小肠移植中早期诊断肝脏GVHD的发生的有效方法之一。     

FTY720诱导大鼠心脏移植物长期存活

目的 观察FTY720对大鼠同种异体心脏移植物存活时间的影响。方法 进行SD Wistar大鼠的腹部异位心脏移植，将受者随机分为对照组、甲泼尼龙(MP)组、环孢素A((SsA)组、FTY720组、FTY720与CsA二药联用组和FTY720、CsA及MP三药联用组，各组按分组要求分别于术前3d至术后14d通过灌胃给予FTY720和CsA，术前1d至术后2d腹腔注射给予MP，观察各组动物术后外周血淋巴细胞数量变化和移植物存活时间。结果 FTY720组、二药联用组和三药联用组的大鼠外周血淋巴细胞在给药后3h开始明显下降，停药后开始回升，至停药14d后恢复正常；移植心脏的存活时间，对照组平均为7．8d，CsA组为16．0d，MP组为27．6d，三药联用组为16．8d，而FTY720组和二药联用组分别超过了150d和124d。结论 FTY720可诱导同种异体大鼠心脏移植物长期存活。     

浸润淋巴细胞凋亡诱导大鼠肝移植耐受

目的观察移植术后大鼠肝脏内不同细胞成分的凋亡现象,寻找耐受过程中的关键细胞成分,探讨大鼠肝移植耐受机制。方法分离肝脏间质细胞,流式细胞仪检测移植术后大鼠肝脏内不同细胞成分的凋亡现象。结果BN→LEW组大鼠移植肝脏在术后早期发生急性排斥反应,并且移植物内间质细胞存在大量的凋亡,急性排斥反应评分及细胞凋亡指数逐渐升高,术后7 d达到高峰随后下降,前者术后28 d与术前无明显差异(P>0.05);细胞凋亡指数至术后28 d较术前仍有明显差异,明显高于LEW→LEW组(P<0.05)。移植物内发生凋亡的细胞为来自于受体的浸润T淋巴细胞。结论移植物排斥反应评分下降与移植肝脏内CTL清除有关,来源于受体的浸润T淋巴细胞凋亡导致移植肝脏免疫耐受。     

Fas配体表达诱导同种胰岛移植免疫豁免

目的　探究睾丸细胞FasL表达能否对同时移植的胰岛移植物提供免疫豁免作用。方法　将不同数量的同种大鼠睾丸细胞与1500个胰岛同时移植于糖尿病受体,观察移植物功能、存活情况,以及移植物内淋巴细胞凋亡情况,并体外检测睾丸Sertoli细胞对活化淋巴细胞的抑制作用。结果　单纯移植胰岛组平均存活期为(5.0±0.5)d。睾丸细胞和胰岛细胞同时移植,当睾丸细胞数为5×106个,平均存活期为(10.0±0.6)d;增加移植睾丸细胞数至1×107个时,存活期大于50d（P＜0.05）。表达FasL的睾丸细胞在移植物内诱导浸润淋巴细胞凋亡,体外抑制淋巴细胞活性。结论　表达FasL的睾丸细胞可诱导浸润的活化淋巴细胞凋亡,使同时移植胰岛移植物获得局部免疫豁免、存活期延长。     

供者基因转染受者细胞诱导特异性免疫耐受的实验研究

目的　探讨供体特异性基因片段MHCClassI类抗原分子RT1.AacDNA在诱导免疫耐受中的作用和可能机制。方法　采用大鼠同种异体心脏异位移植模型,通过供体MHCClassI类抗原的RT1.AacDNA基因片段转染受体成肌细胞（MB）并接种自体胸腺,观察移植物存活时间,判断受体免疫耐受产生和维持的状态。结果　经胸腺接种转染供体基因的自体成肌细胞并同时服用CsA,移植物平均存活时间高达(96.13±12.91)d,明显高于其它实验组（P＜0.05）;动态混合淋巴细胞反应（MLR）,无论外周输注或胸腺接种其对照组cpm值均高于各自实验组;CD4     

转FasL基因的树突状细胞诱导大鼠肝移植免疫耐受的实验研究

目的 观察转FasL基因的树突状细胞（DC）体内注射诱导大鼠肝移植免疫耐受作用,并研究其机制。方法 用“二袖套法”行受体为Wistar大鼠肝移植36例,并随机分为3组：（1）对照组（n＝12）;（2）环孢霉素治疗组（n=12）;（3）转FasL基因治疗组（n=12）,腹腔注射转FasL基因的树突状细胞。手术后7d分别杀死各组4只大鼠,用原位末端标记法及透射电镜观察移植肝细胞及肝脏内淋巴细胞凋亡,其余大鼠用于观察生存期。结果 对照组大鼠在9－15d迅速死亡,TUNEL及电镜观察发现肝细胞变性坏死明显;而环孢霉素治疗组及转FasL基因治疗组免疫排斥以应轻微,移植后大鼠已存活超过6个月,原位末端标记法及电镜均发现FasL基因治疗组肝脏内浸润淋巴细胞凋亡明显。结论 转FasL基因DC细胞治疗能有效地诱导肝移植免疫耐受,其机制是诱导了肝脏内浸润淋巴细胞凋亡。     

肝肠联合移植对小肠移植物免疫保护作用的实验研究

目的研究肝肠联合移植中肝脏对小肠移植物的免疫保护作用。方法建立大鼠肝肠联合移植、单独小肠移植及单独肝移植模型 ,每组取 12只受体大鼠观察生存期 ,另取 6只大鼠分别于移植术后 5、7、14d收集小肠及肝脏移植物 ,进行组织病理学研究并利用半定量RT PCR方法检测移植物中IL 2、IL 4、穿孔素以及颗粒酶B的mRNA表达。结果联合移植组受体生存时间 (2 7 83±4 4 7)d较小肠移植组 (11 5 8± 3 2 6 )d明显延长 (t=7 19,P <0 0 1) ,与肝移植组 (2 8 92± 2 39)d相比 ,差异无显著性 (t=0 75 ,P >0 0 5 )。联合移植组小肠移植物排斥反应较小肠移植组明显减轻 ,穿孔素及颗粒酶B表达水平降低。结论肝 /肠联合移植可以为小肠移植物提供免疫保护。     

落新妇甙对肺移植术后急性排斥反应的作用

目的探讨落新妇甙对大鼠肺移植后机体急性排斥反应的影响和机制，以明确落新妇甙对大鼠肺移植急性排斥反应的作用。方法建立大鼠原位肺移植模型，术后将60只受体大鼠随机分为两组，对照组：术后用生理盐水1ml／d灌胃，实验组：术后用落新妇甙1ml／kg·d灌胃。观察肺移植后大鼠的存活时间、大鼠脾细胞T淋巴细胞转化率、脾淋巴细胞白细胞介素2（IL-2）的活性以及外周血中活化T淋巴细胞凋亡情况。在电子显微镜下观察肺血管超微结构变化。结果实验组大鼠肺移植后存活时间较对照组明显延长（25．4±2．1d vs．13．4±1．2d；t=2．042，P〈0．05）。实验组脾细胞T淋巴细胞转化率较对照组明显降低（23465．8±8783．4 cpm vs．74567．3±12874．6cpm；t=2．284，P〈0．05）；实验组移植大鼠脾淋巴细胞IL-2活性较对照组明显降低（4．25±2．65U／ml vs．23．46±1．82 U／ml；t=3．165，P〈0．01）。实验组能有效地诱导急性排斥反应中活化T淋巴细胞凋亡。实验组肺组织超微结构损伤较对照组减轻。结论落新妇甙通过下调IL-2产生，诱导活化T淋巴细胞凋亡，抑制T淋巴细胞增殖分化，广泛抑制了以T淋巴细胞为主的肺移植术后急性排斥反廊，从而延长肺移槽大鼠的存活时间．     

转化生长因子-β1基因修饰未成熟树突状细胞诱导大鼠肝移植免疫耐受

目的 观察转化生长因子-β1 (TGF-β1)基因转染未成熟树突状细胞(imDC)对大鼠肝移植免疫耐受的诱导作用.方法 利用大鼠骨髓细胞诱导培养imDC,以脂质体介导的pIRES2-EGFP-hTGF-β1转染imDC,于移植前5d输注受体Lewis大鼠体内,移植后分别于3、7、10d抽血检测肝功能[总胆红素( TBIL)和谷丙转氨酶(ALT)]、酶联免疫吸附试验(ELISA)法检测白细胞介素-12(IL-12)水平、肝组织苏木素-伊红(HE)染色急性排斥反应病理评分、原位末端转移酶标记(TUNEL)法检测肝脏淋巴细胞的凋亡及观察各组大鼠肝移植后的生存时间.结果 TGF-β1组移植后肝功能(TBIL和ALT)优于各对照组(P＜0.05);TGF-β1组移植后3、7d血清IL-12浓度分别为71.03±10.70、80.88±14.23均低于各对照组(P＜0.05);TGF-β1组移植后7d出现交界性排斥反应,移植10 d后出现轻度排斥反应(P＜0.05);TGF-β1基因转染组移植后3、7、10d汇管区淋巴细胞凋亡指数分别为6.75±1.93、14.00±2.19、18.25±1.38,较各对照组均明显增高(P＜0.05);TGF-β1组大鼠移植后中位生存期为58 d,明显长于各对照组.结论 TGF-β1基因改造的imDC能诱导大鼠移植免疫耐受,在诱导器官移植耐受中有良好的应用前景.     

FTY720预防大鼠肾脏缺血再灌注损伤的实验研究

目的:研究新型免疫抑制剂FTY720对大鼠肾脏缺血再灌注损伤(IRI)的预防作用.方法:制备大鼠肾脏IRI模型,从下腔静脉注入不同剂量的FTY720,观察术后第1、2、3、5、7 d血清肌酐值(Scr)和术后第2、7 d外周血淋巴细胞数(PLC)的变化,并在术后第2 d取肾脏作组织学检查观察急性肾小管坏死的情况.结果:FTY720处理组动物术后Scr水平显著低于对照组并呈剂量依赖性;FTY720处理组术后第2 d的PLC显著低于对照组;组织学检查显示FTY720处理组肾脏的缺血性损伤轻于对照组.结论:FTY720可以减少PLC,对大鼠肾脏IRI有预防作用.     

FTY720 reduces T-cell recruitment into murine intestinal allograft and prevents activation of graft-infiltrating cells

BACKGROUND: Effective immunosuppression is a critical determinant of graft survival in small-bowel transplantation (SBTx). The present study was designed to determine the potency of FTY720, a newly synthesized immunosuppressant, in rat SBTx and examine the phenotype of graft-infiltrating cells to evaluate its effect on intestinal allografts. MATERIALS AND METHODS: A segment of intestine of Dark Agouti rats was transplanted heterotopically into Lewis rats. The recipients were treated with or without oral FTY720 at a dose of 1 mg/kg per day. Six days after surgery, peripheral blood lymphocytes and lymphocytes from the mesenteric lymph nodes, Peyer's patches, intraepithelial site, and lamina propria of the intestinal allograft were isolated. After the number of lymphocytes in each site was counted, the lymphocyte subpopulations in the intestinal allograft were evaluated by means of a FACScan flow cytometer using several monoclonal antibodies. RESULTS: FTY720 treatment significantly prolonged recipient survival and strongly inhibited rejection histologically in comparison with control rats. FTY720 immunosuppression resulted in a marked reduction of lymphocyte number in the graft epithelium and lamina propria and the proportion of CD8+ and CD25+ cells. FTY720 also significantly decreased T-cell receptors and increased B cells in the graft Peyer's patches. CONCLUSION: FTY720 promoted long-term SBTx recipient survival and maintained the architecture of intestinal allografts. FTY720 immunosuppression may be associated with a reduction of T-cell recruitment subsequent to the redistribution of lymphocyte subpopulations to control the proliferation and activation of graft-infiltrating cells in intestinal allografts.     

Regulation of donor T cells in the tolerant rats to graft-versus-host disease by FTY720 following small bowel transplantation

AIMS: The potency of immunosuppression is a critical factor in small bowel transplantation (SBTx). FTY720 altered lymphocyte trafficking and prevented the donor T cells from migrating into target organs, resulting in the prolongation of recipient survival in acute graft-versus-host disease (GVHD) of SBTx. However, the effect of FTY720 on donor T cells in the chronic phase of GVHD following SBTx remains unclear. METHODS: Heterotopic SBTx was performed in a WF-to-F1 (WF x ACI) rat combination. Recipients were given FTY720 for 14 days after SBTx. The subpopulations of donor-derived T cells and the cytokine production in the target tissues were evaluated on postoperative day 150. RESULTS: FTY720 treatment significantly prolonged recipient survival over 150 days without any clinical signs of GVHD. The numbers of donor-derived CD4+ and CD8+ T cells in the peripheral blood, mesenteric lymph nodes, and Peyer's patches of recipients were maintained at low levels on postoperative 150, which were almost similar to the levels on postoperative day 14. In the host lamina propria, however, a significant higher number of donor T cells (CD4+, 18.4 +/- 4.3 x 10(4); CD8+, 13.9 +/- 3.6 x 10(4)) were still observed on postoperative day 150. Production of interferon-gamma was significantly reduced in target tissues by FTY720 treatment both in the acute and chronic phase. However, interleukin-4 and interleukin-10 production, which was significantly higher on day 14, returned to the level of naive rats in the chronic phase. CONCLUSIONS: A 14-day treatment of FTY720 induced tolerance in our SBTx model. Down-regulation of both Th1 and Th2 immune response was observed in the chronic phase.     

Prevention of GVHD and graft rejection by a new S1P receptor agonist, W-061, in rat small bowel transplantation

BackgroundIn small bowel transplantation (SBTx), inhibition of both graft-versus-host disease (GVHD) and allograft rejection is necessary.MethodsWe investigated the potency of a new sphingosine-1-phosphate receptor agonist, W-061, for these two immune responses in SBTx. W-061 has a completely different molecular structure from FTY720. Heterotopic SBTx was performed from Wistar-Furth (WF) into (WF × ACI) F1 rats as a GVHD model or F1 to WF rats as a rejection model. Recipients were orally given 3 mg/kg/day W-061 for 14 days after SBTx. Recipient survival, body weight, histopathology, lymphocyte subpopulations, and the cytokine profile were evaluated.ResultsW-061 treatment significantly prolonged graft survival over 100 days in four out of six recipients in the GVHD group and over 60 days in three out of six recipients in the rejection group. W-061 strongly inhibited GVHD and rejection as seen histopathologically in comparison with untreated control rats. W-061 caused a significant reduction in donor-derived T cells in target organs and infiltrating T cells in allografts by promoting these cells to home into the secondary lymphoid tissues and sequestrating those cells there. W-061 significantly decreased production of interferon-γ in target organs and allografts.ConclusionTherefore, these data suggest that W-061 has considerable potential as a new therapeutic immunosuppressant in patients with SBTx.     

Rejection following donor or recipient preoperative treatment with FTY720 in rat small bowel transplantation

BACKGROUND: Severe rejection of small bowel transplantation (SBTx) has been ascribed to abundant lymphoid tissues in the small intestine without well-established evidence. However, the role of donor lymphocytes in rejection is still unclear. The novel immunosuppressant, FTY720, is reported to transfer peripheral blood lymphocytes (PBLs) to lymphoid tissues such as mesenteric lymph nodes (MLNs) and Peyer patches (PP). In the present study, the number of donor lymphocytes in the graft was increased by FTY720, and the influence on rejection was studied in a rat model. Furthermore, the number of the PBL of recipient was decreased by FTY720 before SBTx and the effect on rejection was examined. MATERIALS AND METHODS: Orthotopic total SBTx was performed in Brown-Norway and Lewis rats. In the donor pretreatment study, FTY720 was administrated to donor rats 24 h prior to harvesting to increase the number of graft lymphocytes (FTY donor-pretreated group). In contrast, MLNs were surgically removed from the grafts to decrease the number of graft lymphocytes (MLN-resected group). In the recipient pretreatment study, FTY720 was administrated to recipient rats 24 h before SBTx to decrease recipient PBL (FTY group). In contrast, a subclinical dose of cyclosporine A (CsA) was administrated after SBTx (CsA group). Rats were administrated preoperative FTY720 combined with post-SBTx CsA (FTY+CsA group). Graft survival, pathology, lymphocyte count, and subtype were examined. RESULTS: In the donor pretreatment study, pretreatment with FTY720 did not enhance graft rejection. MLN resection did not prolong graft survival. In the recipient pretreatment study, FTY720 caused a significant reduction in the number of infiltrating lymphocytes in the graft, as well as the percentage of recipient CD4+ and CD25+ cells within the graft. FTY720 and CsA synergistically prolonged graft survival. CONCLUSION: SBTx rejection correlated with the number of recipient PBL, and not with the number of donor lymphocytes transplanted together with the graft. The pretreatment of the recipient with FTY720 was effective in the case of combined use of the low-dose postoperative CsA.     

Effect of FTY720 and ex vivo graft irradiation in rat small bowel transplantation: apoptosis of crypt cells and lymphocytes

OBJECTIVE: We investigated the extent of apoptosis in crypt cells and Peyer's patches (PPs) during small bowel allograft rejection in rats to examine the effect of FTY720 and ex vivo graft irradiation during rejection. MATERIALS AND METHODS: Orthotopic small bowel transplantations (SBT) were performed from Brown Norway (BN) rats to Lewis (LEW) rats. Four groups of SBT animals were studied on days 3, 5, and 7 after operations: untreated allograft, allograft with FTY720, allograft with irradiation, and allograft with FTY720+irradiation. Cryostat sections were prepared from the grafts, including PPs. An in situ end-labeling (ISEL) technique was used to detect apoptotic cells. Indirect immunoperoxidase staining was also performed using monoclonal antibodies against rat Fas/FasL. RESULTS: The graft survival was prolonged in the FTY720-treated groups. In the FTY720-treated group, the number of ISEL-positive enterocytes was significantly down-regulated on days 3, 5, and 7 compared with the untreated allograft group. The number of ISEL-positive mononuclear cells was also significantly down-regulated compared with the untreated allograft group. The FTY720 the radiation and the FTY720+irradiation treated groups showed significantly down-regulated numbers of Fas/FasL-positive enterocytes on day 7 compared with the untreated allograft group. Fas/FasL-positive mononuclear cells were also significantly down-regulated in the allograft compared with the untreated allograft group. CONCLUSIONS: FTY720 and ex vivo graft irradiation prevented up-regulation of the number of apoptotic enterocytes, lymphocytes, and Fas/FasL-positive lymphocytes, and also prolonged small bowel allograft survival. Combination FTY720 and ex vivo graft irradiation did not affect graft survival and apoptotic cell expression compared with the FTY720 only group. These findings suggest that FTY720 may prevent both rejection-associated and sepsis-induced apoptosis during the late phase of small bowel graft rejection.     

Long-term effect of FTY720 on lymphocyte count and islet allograft survival in mice

This study was performed to observe the long-term effect of FTY720 on lymphocyte count change and islet allograft survival. Diabetic C57BL/6 mice were given FTY720 (group 1, 0.5 mg/kg/day; group 2, 1.0 mg/kg/day) or its vehicle (group 3, controls) after transplantation. Median graft survival time was prolonged in a dose-dependent manner (group 1, 84.5 days; group 2, >100 days, and group 3, 10 days, P < 0.01). Peripheral blood lymphocytes in groups 1 and 2 decreased to 23.81% and 12.59% compared with control group after FTY720 treatment. Lymphocytes from mesenteric lymph nodes and axillary nodes in groups 1 and 2 significantly increased on day 5, but decreased on day 14. Lymphocyte infiltration to the graft site was attenuated in groups 1 and 2. In conclusion, continuous FTY720 administration can induce and maintain lymphopenia, and inhibit lymphocytes from infiltrating the graft site so as to prolong islet allograft survival in mice.     

Control of intestinal allograft rejection by FTY720 and costimulation blockade

INTRODUCTION: The clinical application of small bowel transplantation (SBTx) is hampered by its pronounced immunogenicity. In this study we examined the effects of the novel immunosuppressant FTY720 and costimulation blockade by an anti-CD40L mAb (MR-1) in a stringent mouse model of SBTx. METHODS: SBTx was performed in mice with a full MHC mismatch (donors: C3H=H-2(k); recipients: C57BL/6=H-2(b)). Recipients were divided into four groups: 1, untreated group; 2, MR1 monotherapy (500 microg IV on days 0, 2, 4, and 7); 3, FTY720 monotherapy (1 mg/kg body weight PO for 14 consecutive days after transplantation); 4, FTY720 plus MR1-treated group. Graft rejection grades were assessed by H&E staining. Graft mesenteric lymph nodes (MLNs), Peyer's patches (PPs), as well as intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) were analyzed by flow cytometry and three-color immunofluorescence staining. RESULTS: Neither FTY720 nor MR1 monotherapy was efficient in preventing the rejection of mouse intestinal allografts, whereas FTY720 plus MR1 profoundly inhibited the rejection response at the 14th posttransplant day. The infiltration of host lymphocytes was reduced in graft MLNs, PPs, IELs, and LPLs by FTY720 therapy. FTY720 plus MR1 inhibited host CD8(+) T-cell infiltration in graft LPLs when compared with grafts treated with FTY720 only. Additionally, two subpopulations, CD11b(+high) Gr1(-) and CD11b(+intermediate) Gr1(+) cells, were decreased in FTY720-treated grafts. CONCLUSIONS: FTY720 plus MR1 efficiently delayed intestinal allograft rejection in a mouse model by preventing the infiltration of host lymphocytes, particularly of CD8(+) cells.     

Effect of FTY720 in rat small bowel transplantation: apoptosis of crypt cells and lymphocytes in gut-associated lymphoid tissues

AIM: We investigated the extent of apoptosis in crypt cells and Peyer's patches (PPs) during small bowel allograft rejection in rats to examine the effect of FTY720 during rejection. METHODS: Orthotopic small bowel transplantations (SBTs) were performed from BN to LEW rats. Isografted animals served as controls. Three groups of SBT animals were studied on days 3, 5, and 7 after operation: isograft, untreated allograft, allograft with FTY720. FTY720 was orally administered by gavage (1 mg/kg/d) to allograft recipients on 7 consecutive days. Cryostat sections were prepared from grafts, including PPs. An in situ end-labeling (ISEL) technique was used to detect apoptotic cells. Indirect immunoperoxidase staining was also performed using monoclonal antibodies against rat Fas/Fas-L. RESULTS: Graft survival was prolonged in the FTY720-treated group. The number of ISEL-positive enterocytes in the allografts increased significantly on days 3, 5, and 7 compared with the isograft group. In the FTY720-treated group, the number of ISEL-positive enterocytes in the allografts was down-regulated significantly on days 3, 5, and 7 compared with untreated allograft group. In the PPs, the number of ISEL-positive mononuclear cells increased significantly in the allografts compared with the isograft group. In the FTY720-treated groups, the number of ISEL-positive mononuclear cells were down-regulated significantly in the allografts compared with the untreated allograft group. The number of Fas/FasL-positive enterocytes were increased significantly in allografts compared with isograft group. In FTY720-treated groups, the number of Fas/FasL-positive enterocytes were down-regulated significantly on day 7 compared with the untreated allograft group. In the PPs, Fas/FasL-positive mononuclear cells also increased significantly on day 7 in the allografts compared with isografts. In the FTY720-treated groups, Fas/FasL-positive mononuclear cells were down-regulated significantly in the allografts compared with the untreated allograft group. CONCLUSIONS: The number of apoptotic enterocytes, lymphocytes, and Fas/FasL-positive lymphocytes increased during small bowel graft rejection. FTY720 prevented up-regulation of the number of apoptotic enterocytes, lymphocytes, and Fas/FasL-positive lymphocytes while also prolonging small bowel allograft survival.     

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.