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介导淋巴细胞凋亡抑制小肠移植的移植物抗宿主免疫反应

目的 探讨免疫调节药物FTY720对小肠移植后急性移植物抗宿主病（GVHD）的治疗效果及其作用机制.方法 应用Wistar-Furth（WF）大鼠作为供体,WF和ACI大鼠的子代（F1）作为受体,同种异基因异位全小肠移植的技术方法建立GVHD的动物模型.移植受体分为实验组和对照组,每组6只.实验组从移植手术当日开始予以FTY720治疗,持续14 d;对照组在相同的时间段口服蒸馏水.术后第15天,提取受体靶器官肝脏、小肠及移植物小肠的淋巴细胞,应用免疫组织化学（免疫组化）TUNEL法和流式细胞仪检测两组淋巴细胞凋亡的变化.结果 对照组大鼠术后均死亡于GVHD,平均生存时间（16.0±1.7）d,实验组大鼠均长期成活超过100 d,两组差异具有统计学意义（P＜0.01）.免疫组化TUNEL法检测结果显示,实验组肝脏和移植物小肠黏膜的淋巴细胞凋亡比率均明显高于对照组,差异具有统计学意义（P＜0.05）.流式细胞技术分析结果显示,实验组大鼠移植物小肠黏膜内凋亡的淋巴细胞百分比为19.4%,明显高于对照组的11.8%（P＜0.05）;而肝脏凋亡的淋巴细胞百分比两组差异无统计学意义（P＞0.05）.结论 FTY720可能通过诱导淋巴细胞的凋亡,减少和抑制GVHD对靶器官的损害,改善移植大鼠的预后.     

Effect of FTY720 in rat small bowel transplantation: expression of mucosal addressin cell adhesion molecule-1

AIM: Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) mediates the homing of lymphocytes to gut-associated tissues (GALT). We performed a semiquantitative analysis of MAdCAM-1 expression during small bowel graft rejection in rat treated with FTY720. METHODS: Orthotopic small bowel transplantations (SBT) were performed from BN rats to LEW rats. Isografted animals served as controls. Three groups of SBT animals were studied on days 3, 5, 7 after operations (Isograft, untreated allograft, allograft with FTY720). FTY720 was orally administered by gavage (1 mg/kg/d) to allograft models on 7 consecutive days. Cryostat sections were prepared from grafts, including Peyer's patches (PPs). Indirect immunoperoxidase staining was performed using mAbs against MAdCAM-1. The degree of vascular endothelial staining on high endothelial venules (HEV) in the PPs was graded from 1 (low levels) to 5 (high levels), and in the vessels of the lamina propia from 1 (faint), to 2 (low at the base of villi), 3 (low to the middle of villi), 4 (high to the middle of villi), to 5 (high to villi tip). RESULTS: The graft survival was prolonged in the FTY720-treated group. MAdCAM-1 expression on HEVs in PPs was down-regulated during rejection. In contrast its expression on endothelial cells of vessels in the lamina propria was up-regulated during rejection. In the FTY720-treated groups, MAdCAM-1 expression on HEVs in PPs was up-regulated and its expression on endothelial cells of vessels in the lamina propria was down-regulated compared with untreated allograft group. CONCLUSIONS: Alteration in MAdCAM-1 expression may be associated with the development of SB graft rejection. The vessels at the base of villi, which are associated with lymphocyte recruitment, may become sites of intestine immune reactivity during the early phase of small bowel allograft rejection. FTY720 was found to prevent the down-regulation of MAdCAM-1 expression on HEVs in PPs and the up-regulation of its expression on endothelial cells of vessels in the lamina propria while also prolonging small bowel allograft survival.     

Prevention of graft rejection and graft-versus-host reaction by a novel immunosuppressant, FTY 720, in rat small bowel transplantation

In the present study, we examined the immunosuppressive effect of a new drug, FTY 720, on small bowel transplantation (SBT) in rats. Grafts from (LEW × BN) F 1-to-LEW rats treated with FTY 720 at 0.5 mg/kg from day 0 to 14 post-SBT survived significantly longer than untreated grafts. In addition, the administration of FTY 720 combined with cyclosporin (CyA; 5 mg/kg per day) had a synergistic effect on allograft survival. The graft-versus-host reaction (GVHR) that occurred in the LEW-to-F 1 rats was markedly reduced after the administration of FTY 720. FTY 720 combined with a low dose of CyA completely abrogated GVHR without any adverse reaction. FTY 720 treatment resulted in a significant decrease in the number of lymphocytes in the peripheral blood and the spleen, but the number of peripheral neutrophils was unchanged. Thus, FTY 720 would appear to be an ideal drug to combine with CyA in order to control the immune reaction after SBT. Received: 19 February 1997 Received after revision: 23 May 1997 Accepted: 9 June 1997     

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.     

FTY720诱导大鼠系膜细胞的凋亡

目的 观察新型免疫抑制剂FTY720对体外培养的正常大鼠肾小球系膜细胞（GMC）的促凋亡作用及其对细胞周期调节蛋白基因表达谱的影响,以探讨其作用机制。 方法 体外培养大鼠GMC,加入20 μmol/L FTY720,分别作用6 h、12 h、24 h、48 h后,以MTT法检测GMC增殖情况;流式细胞术检测GMC凋亡;Hoechst33258和PI染色观察凋亡细胞形态变化;琼脂糖DNA凝胶电泳法观察凋亡细胞核小体DNA的断裂现象。并通过SuperArray 实时定量PCR细胞周期基因芯片测定FTY720对细胞周期调节蛋白基因表达谱的影响。 结果加入FTY720培养6 h 后,流式细胞术检测发现,GMC出现典型细胞凋亡的亚二倍体峰;12 h后Hoechst33258和PI荧光染色观察发现亮蓝色的凋亡小体,且开始出现典型细胞凋亡形态改变;24 h后DNA琼脂糖凝胶电泳可见凋亡梯度的出现。随FTY720作用时间延长,细胞凋亡明显增加,不同时间组间细胞凋亡率差异有统计学意义（P < 0.01）。SuperArray 实时定量PCR细胞周期基因芯片发现FTY720分别显著上调系膜细胞Dnajc2、LOC688900、RGD1562436_predicted基因表达,分别达41.6、38和16倍。 结论 FTY720 在体外可呈时间依赖诱导正常大鼠GMC凋亡,其机制与影响细胞周期调节蛋白及凋亡相关基因的表达有关。     

Effect of FTY720 on apoptosis of smooth muscle cells

BACKGROUND: Hyperproliferation of smooth muscle cells (SMCs) plays a key role in allograft arteriosclerosis. This prompted us to investigate the effect of the novel immune modulator and synthetic sphingolipid FTY720 on apoptosis of SMCs. METHODS: Rabbit SMC cultures were treated with FTY720 and apoptosis and necrosis were detected by fluorescence microscopy. RESULTS: We investigated dose- and time-dependent effects of FTY720 and found that clinically relevant low doses of FTY720 (<1 micromol/L) did not induce apoptosis, whereas 10 micromol/L FTY720 induced apoptosis after 48 hours incubation. CONCLUSION: At doses of FTY720 used in clinics for treatment of renal allografts and multiple sclerosis. FTY720 did not induce SMC apoptosis.     

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.     

Protective effects of ex vivo graft radiation and tacrolimus on syngeneic transplanted rat small bowel motility

BACKGROUND: Intestinal transplantation is unduly complicated by the nontolerogenic properties of the gut-associated lymphoid tissue. Because simultaneous graft irradiation and bone marrow infusion significantly prolong the survival of the small bowel transplanted animal, our objective was to determine the functional motility effects of the immune modulating, graft irradiation procedure in the presence and absence of tacrolimus immunosuppression. METHODS: Four groups of syngeneic orthotopic small bowel transplanted animals were studied 48 hours after operations (untreated, tacrolimus, ex vivo graft irradiation, and tacrolimus + irradiation) and compared with controls. Histologic analysis was performed for mucosal apoptosis and neutrophilic infiltration into the muscularis externa. Gastrointestinal in vivo transit and in vitro circular muscle strip contractions were quantified in response to bethanechol (0.3-300 micromol/L). RESULTS: Graft irradiation ex vivo alone or in the presence of tacrolimus significantly increases (> 10-fold) the number of apoptotic mucosal cells after transplantation. Functional measurements showed that transplantation resulted in a significant delay in gastrointestinal transit and a decrease in muscle strip contractility. Tacrolimus and graft irradiation significantly ameliorated the transplant-induced dysfunction. CONCLUSIONS: Given the endowed propensity of mucosal regeneration, the immunologic and functional benefits of ex vivo graft irradiation appear to outweigh the detrimental effects to the mucosa.     

FTY720对小鼠外周血淋巴细胞的影响

目的　观察FTY72 0对近交系小鼠外周血淋巴细胞的影响。方法　选用近交系雄性C5 7BL/ 6小鼠 ,连续口服FTY72 0 (3mg·kg-1·d-1) 14d。每只动物于服药后 2、4、6、8、12、2 4h以及停药后 1、2、3、4、5、6周自尾静脉采血 ,计数淋巴细胞数。结果　服用FTY72 0后 ,小鼠外周血淋巴细胞迅速减少 ,2h后即由服药前的 (870 0± 6 5 6 ) / μl降至 (3783± 176 ) / μl(P <0 .0 1) ,并于 4h降至最低值 (2 4 6 7± 2 5 2 ) / μl,之后基本保持稳定。停用FTY72 0后小鼠外周血淋巴细胞没有立刻开始恢复 ,在低水平徘徊 2周后 ,第 3周淋巴细胞数开始出现明显回升 ,停药后第 6周恢复到 (7833± 76 4 ) / μl,与服药前相比 ,差异无显著性 (P >0 .0 5 )。结论　FTY72 0起效迅速 ,特异性强 ,且作用可逆。     

Protection of mouse small bowel allografts by FTY720 and costimulation blockade

BACKGROUND: The clinical application of small bowel transplantation (SBTx) is hampered by its pronounced immunogenicity. We aimed to test the hypothesis that prolonged sequestration of lymphocytes in secondary lymphoid organs may enhance the alloprotective effect of costimulation blockade. METHODS: For this purpose, recipients of intestinal allografts were treated with MR1, FTY720, combined FTY720 plus MR1, or were left untreated. Grafts were examined 6 and 14 days after transplantation by applying a histologic rejection score, multiparameter-immunofluorescent staining, and flow cytometry. RESULTS: FTY720 or MR1 monotherapy did not prevent the rejection of mouse intestinal allografts, whereas combined therapy with FTY720 plus MR1 profoundly inhibited rejection at day 6 and day 14 after transplantation. In FTY720-treated mice infiltration of host lymphocytes in graft mesenteric lymph nodes, Peyer's patches, intraepithelial lymphocytes, and lamina propria lymphocytes (LPLs) was reduced on day 6. Anti-CD40L antibody improved the rejection score at day 14 but had no effect at day 6. Importantly, host CD8 T-cell infiltration in graft LPLs was significantly reduced compared with all other groups. CONCLUSION: FTY720 plus MR1 effectively inhibited intestinal allograft rejection in mice, possibly by enhancing the alloprotective effects of costimulation blockade by prolonged sequestration of lymphocytes in secondary lymphoid organs.     

肠康复治疗对促进移植小肠结构修复作用的观察

目的：观察小肠移植术后应用肠康复治疗（生长激素和谷氨酰胺强化的TP支持）对移植小肠结构修复的促进作用。方法：采用大鼠异基因异位全小肠移植及TPN模型48只，分为4组，每组12只。I组：标准TPN组；Ⅱ组：谷氨酰胺强化TPN组；Ⅲ组：生长激素组，STPN的基础上加用生长激素；Ⅳ组：肠康复治疗组。生长激素用法为术后第1天起每日皮下注射1U／kg,GTPN每日补充谷氨酰胺3．6g/kg,CsA为每日肌注10mg/kg。术后检测各组移植小肠粘膜的形态学参数。结果：I组移植小肠粘膜在术后第8天明显萎缩，其它3组移植小肠粘膜的改变显著轻于I组。术后第14天。I组各参数进一步下降，而其它3组已开始恢复，特别是Ⅳ组，各指标与术前水平已无明显差异并且显著优于I组。结论：联合应用谷氨酰胺和生长激素的肠康复治疗顺应了移植术后机体的代谢特点，能够更为有效地促进移植小肠粘膜结构的修复。     

Induction of apoptosis in human bladder cancer cells in vitro and in vivo caused by FTY720 treatment

PURPOSE: FTY720 is a unique immunosuppressant that induces apoptosis in activated lymphocytes but not in other hematopoietic cells. We examined whether FTY720 has anticancer effects on human bladder cancer cells by inducing apoptosis and we investigated its molecular pathway. MATERIALS AND METHODS: We used the 3 human bladder cancer cell lines T24, UMUC3 and HT1197, and the human fibroblast derived cell line CRL-2096 (American Type Tissue Collection, Rockville, Maryland) in this study. The difference in drug susceptibility to FTY720 in cancer cells and fibroblasts was examined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and cell growth assays. FTY720 induced apoptosis was determined by morphological analysis under light and electron microscopy, and DNA electrophoresis, and its molecular pathway was evaluated by Western blot analysis focusing on the p42/p44 mitogen activated protein kinase pathway. We then tested the in vivo effect of this agent using 2 mouse models of human bladder cancer xenograft. RESULTS: FTY720 treatment in vitro induced selective apoptosis in cancer cells at a concentration of less than 10 microM. Morphological analysis revealed features characteristic of apoptosis, including small cytoplasm with fragmented nuclei and condensed chromatin. DNA electrophoresis confirmed apoptosis, as evidenced by a distinct oligosomal ladder. Western blot analysis revealed that the agent significantly inhibited hepatocyte growth factor induced p42/p44 mitogen activated protein kinase activity. The in vivo anticancer effect was clearly confirmed by significantly decreased tumor growth without notable side effects in the 2 xenograft models. CONCLUSIONS: FTY720 treatment may induce selective apoptosis in vitro as well as in vivo in cancer cells. We suggest that FTY720 is a potent and clinically applicable anticancer agent for bladder cancer.     

Novel mediators of FTY720 in human lymphocytes

FTY720 (FTY), a novel immunosuppressive drug, can be distinguished from other immunosuppressive drugs by a completely different mechanism of action. FTY induces altered lymphocyte trafficking, leading to peripheral blood lymphopenia and to increased lymphocyte counts in lymph nodes. FTY mediates its immune-modulating effects by binding to sphingosine 1-phosphate receptors expressed on lymphocytes. In an attempt to identify mediators of the FTY-induced signal transduction, we used a proteomic approach. FTY-treated peripheral blood lymphocytes (PBLs) were investigated for the expression of 622 proteins. We identified 15 differentially expressed proteins in PBLs possibly related to FTY action. As indicated by protein function, several identified proteins could be linked to the cytoskeleton/cell motility, to cell adhesion, and vesicle trafficking. No changes were found concerning the expression of various apoptosis regulators as well as the immunophilins FKBP12 and calcineurin. Our data suggest that FTY affects cytoskeleton rearrangements, cell adhesion, and vesicle trafficking/sorting in human PBLs.     

Immunologic benefits of longer graft in rat allogenic small bowel transplantation

BACKGROUND: The effect of graft length on rejection reaction in small bowel transplantation (SBT), which is poorly understood, is tested using rat allogenic SBT models with a short course of tacrolimus. MATERIALS AND METHODS: Inbred Brown Norway rats (major histocompatibility complex: RT1) and Lewis rats (RT1) were used as donors and recipients, respectively. The intestinal tract of the recipient was partially or totally replaced by segmental (15 cm) or whole (70 cm) donor intestine, using two different SBT models. With tacrolimus treatment (0.64 mg/kg per day, 0-13 postoperative days, intramuscularly), recipients' body weights and their survival were evaluated. To compare the extent of peripheral chimerism, donor passenger leukocytes were followed using flow cytometry with a donor-specific monoclonal antibody, OX-27. For the periodical histologic analysis, heterotopic SBT and protocol biopsies of the graft were also performed with short or long intestinal grafts. RESULTS: In a classical Monchik and Russell orthotopic SBT model, whole SBT recipients survived more than 60 days. However, all of the allogenic segmental SBT recipients died within 14 days without histologic sign of graft rejection. In the modified orthotopic SBT model using a cuff technique without systemic clamping, all recipients with segmental allograft survived longer than 29 days. However, recipients with whole graft tended to survive longer than those with segmental graft. The suffering period, lasting from the onset of rejection to death, was significantly shorter in the segmental group than in the whole group. Flow cytometric analysis showed that recipients with whole intestinal grafts had significantly higher ratio of donor passenger leukocytes in peripheral blood. Histologic studies of the protocol biopsies showed that the shorter graft tended to be more severely rejected than the longer graft. CONCLUSIONS: We have demonstrated experimentally that long intestinal grafts have immunologic advantage over short grafts.