小肠移植后排斥反应的监测

检测猪同种异体小肠移植后受体的血浆Ｎ－乙酰氨基已糖酶，外周血单个核细胞前凝血质活性，血清肿瘤坏死因子，血清白细胞介素２和白细胞介素６，并与同期的粘膜活检结果对照，发现它们在排斥早期即有显著升高，其是单个核细胞前凝血活性和白细胞介素２的变化早于反排斥反应的病理变化，提示术后检测这些指标将有助于排斥反应的早期诊断。     

小肠移植排斥的研究进展

移植排斥是临床小肠移植遇到的最大困难，本文对小肠移植排斥的特点、临床分级、诊断及监测控制排斥的最新进展作一综述。     

小肠移植排斥的研究进展

移植排斥是临床小肠移植遇到的最大困难,本文对小肠移植排斥的特点、临床分级、诊断及监测控制排斥的最新进展作一综述。     

小肠移植与慢性排斥反应

小肠移植近年来有了很大发展,正逐渐成为一种现实可行的手段应用于临床.但是,和心脏、肺脏、肝脏、肾脏移植一样,慢性排斥反应正逐渐成为影响移植物远期生存的重要因素.目前,随着对于慢性排斥反应机理认识的深入,人们也在不断尝试不同的治疗方法和对策.     

小肠移植后急性排斥反应的新进展

小肠功能衰竭病人经全胃肠外营养（TPN）后可长期存活．然而．持续TPN会导致严重的并发症如TPN相关性终末期肝病、静脉通道丧失以及反复性败血症，往往导致病人在半年内死亡。因此，小肠移植成为惟一能够选择的治疗手段。经过近半个世纪的探索，临床小肠移植疗效得到很大改善。迄今最长1例小肠移植病人已存活达17年之久。1985年4月至2003年3月期间。全球61个医学中心共计对923例病人进行了989例次小肠移植，移植小肠1年生存率达64％。但是，与其他实质性脏器移植比较，小肠移植的效果仍不尽如人意。移植后急性排斥的发生率高（57％）是阻碍小肠移植发展的主要因素。本文综述了小肠移植后急性排斥反应的发生机制和免疫抑制方面的新进展。     

细胞因子在小肠移植排斥反应中的作用

小肠移植是治疗终末期小肠功能衰竭的理想治疗手段。小肠属于人体内最大的淋巴库，含有大量免疫活性细胞，同时也是体内最大的细菌库，因此小肠移植后常因发生严重的免疫排斥反应和感染而导致手术失败。小肠移植不但有受者对供者的移植排斥反应，还有供者对宿主的反应。多数移植后患者临床表现复杂，反应剧烈，严重妨碍了小肠移植的推广。     

亲属活体小肠移植后急性排斥反应的监测与治疗一例

目的探讨亲属活体小肠移植后急性排斥反应的监测与治疗。方法对1例短肠综合征患者施行亲属活体小肠移植，手术分两期进行。供者为患者的母亲，供、受者HLA有4个抗原相符。移植肠段长120cm，一期手术时供、受者肠道不进行吻合，移植肠两端在腹壁造口，一期手术后188d，再行二期手术，分别将受者残存小肠的近端、远端与移植肠袢的近端、远端作端侧吻合。术后观察移植小肠引流液的性状，定期内镜观察，并行移植肠组织学检查。采用他克莫司、霉酚酸酯及甲泼尼龙预防排斥反应，并予两剂达利珠单抗诱导。结果受者两次手术均顺利。一期手术后37d出现急性排斥反应，给予皮质激素冲击治疗9d，未能逆转，后改为莫罗单抗-CD3治疗8d后逆转。术后121d，肠镜及组织学检查证实移植肠修复良好，小肠绒毛形态及结构基本正常，D-木糖吸收试验提示移植肠吸收功能改善。现患者已存活213d，体重增加4．5kg，进半流质饮食，生活自理。结论小肠移植后可采取肠镜和组织学检查，并结合临床表现来综合判断排斥反应。发生急性排斥反应时，及时予以激素冲击治疗，无效时可用莫罗单抗-CD3。     

rhIL-10抑制小肠移植急性排斥反应的研究

目的观察rhIL-10对小肠移植急性排斥反应和T细胞增殖的抑制作用。方法将移植后的大鼠随机分为同基因组、对照组和3种不同剂量的rhIL-10治疗组，各组n=6。术后3、5、7d取移植肠管，行病理检查，测外周血T细胞亚群及术后7d肝、肾功能的重要参数：天冬酸氨基转移酶（AST）、丙氨酸氨基转移酶（ALT）、血肌酐（Crea）和血尿素（BUN）。结果对照组术后3d发生轻度排斥，5d发生中度排斥，7d发生重度排斥；中、高剂量组除部分标本在术后5、7d发生轻度排斥外，无排斥征象；低剂量组与对照组改变相似，但排斥的病理改变发生较晚、较轻。术后3、5、7d，低、中、高剂量组外周血CD3^＋T细胞数及CD4^＋／CD8^＋比值与对照组比较差异有统计学意义（P〈0．05）。各组AST、ALT、Crea和BUN差异均无统计学意义（P〉0．05）。结论（1）对小肠移植急性排斥的抑制，低剂量作用是明确的，但疗效有限。中、高剂量作用较明显；与同基因组、对照组比较，不增加肝、肾毒副作用；（2）动态检测外周血CD3^＋T细胞数及CD4^＋／CD8^＋比值可作为器官移植术后监测排斥反应的重要指标之一。     

雷公藤联合小剂量环孢素A抑制猪小肠移植排斥反应

用猪行同种异体节段性小肠移植实验。４头猪术后给大剂量环孢素Ａ（ＣｓＡ），１００天后改为口服雷公藤，结果２头猪于９２和９７天死于肺炎，另２头存活时间分别超过２８１天和３０２天。５头猪术后给小剂量ＣｓＡ，存活１２±３天，均死于急性排斥。５头猪术后给雷公藤和小剂量ＣｓＡ，１００天后改为单独口服雷公藤，结果３头猪存活时间分别超过１６６天、２７４天及２７４天，１头猪于１３５天不明原因死亡，另１头猪于１６６天因自身肠梗阻死亡，本组５头猪均未出现严重感染。表明雷公藤具有一定的抗排斥作用；雷公藤联合小剂量ＣｓＡ既可抑制排斥，又可避免并发严重感染。     

阻断共刺激信号抑制小鼠小肠移植排斥反应机制的研究

目的证实细胞毒T淋巴细胞相关抗原4免疫球蛋白（CTLA4-Ig）能抑制小鼠小肠移植排斥反应，并研究其作用机理。方法采用显微外科技术建立小鼠异位小肠移植模型，实验分为3组。A组：为同系移植组（供、受者均为BALB／c小鼠）；B组：为同种移植未治疗组（供者为C57BL／6小鼠，受者为BALB／c小鼠），移植后未给予任何治疗；C组：为同种移植共刺激信号阻断组（供者为C57BL／6小鼠，受者为BALB／c小鼠），移植后第2d开始腹腔注射CTLA4-Ig 1mg·kg^-1·d^-1，连用3d。术后观察各组受者的存活时间；移植第6d处死部分受者获取移植物标本，进行组织病理学检查；半定量逆转录聚合酶链反应检测白细胞介素2（IL2）、白细胞介素10（IL-10）、7干扰素（IFN-7）、吲哚胺2，3-双加氧酶（IDO）的mRNA水平；蛋白质印迹法检测移植物中IDO蛋白表达水平。结果A组和C组的中位存活时间均为30d，B组的中位存活时间为6d。A、C组与B组比较，差异有统计学意义（P〈0．01）。病理结果显示，B组排斥反应明显，C组呈轻度排斥反应。IL-2、IFN-γ的mRNA表达水平在A组、C组均较低，而B组则显著增加；IL-10的mRNA转录水平在A、B组较低，C组明显增高。IDO分子mRNA和蛋白的表达检测显示，A、B组的1130分子mRNA和蛋白表达低，c组增高显著。结论应用CTLA4-Ig能抑制小鼠小肠移植排斥反应。IL-2、IFN-γ分子mRNA的高水平表达和排斥反应的程度呈正相关，IL-10分子mRNA表达与排斥反应强度呈负相关。CTLA4-Ig阻断共刺激信号导致T细胞的无能与IDO表达明显相关，说明了IDO所致的“色氨酸饥饿”可能是共刺激信号被阻断后导致活化T细胞无能的机制之一。     

Induction of graft-versus-host disease and rejection by sensitized small bowel allografts

This study was undertaken to investigate under which circumstances graft versus host disease occurs following fully allogenic small bowel transplantation in the rat. To facilitate the development of GVHD, Brown-Norway donors were specifically sensitized against the Lewis hosts prior to transplantation. Additionally, the Lewis recipients were immunocompromised before transplantation using splenectomy, cyclosporine, and antilymphocyte serum. No further immunosuppressive therapy was administered after transplantation. When all pretreatment regimens were used, acute lethal GVHD arose in two of nine animals (22%), whereas in two animals (22%) signs of acute GVHD and rejection were observed concurrently. When recipients of sensitized grafts were pretreated with CsA alone, one of eight animals (12.5%) showed signs of GVHD and rejection. All other animals died of acute rejection without clinical signs of acute GVHD. However, histological signs of GVHD were observed frequently in hosts grafted with a sensitized small bowel transplant. These data show that acute lethal GVHD can occur when an immunocompromised host is grafted with a sensitized intestinal transplant.     

CTLA4IgG treatment induces long-term acceptance of rat small bowel allografts

BACKGROUND: CTLA4 immunoglobulin (Ig)G that binds to B7 effectively inhibits the signaling of CD28/CTLA4-B7 pathway and induces antigen specific T cell unresponsiveness in vitro and in vivo. Using CTLA4IgG, we examined induction of long-term graft survival and the mechanism of maintenance of tolerance in rat allogeneic small bowel transplantation. METHODS: Small bowels of Brown-Norway rats (RT1n) were heterotopically transplanted into Lewis rats (RT1l). Recipients were treated with an i.p. injection of either CTLA4IgG or control IgG for 7 days. RESULTS: Long-term survival was observed in rats treated with CTLA4IgG, whereas control rats died within 16 days after transplantation. To examine whether a tolerant state was established in long-term survival rats, secondary transplantation was performed using small bowels of Brown-Norway rats or ACI (RT1b) rats. It was demonstrated that small bowels of Brown-Norway rats were accepted; however, those of ACI rats were rejected within 10 days. Serum concentrations of interleukin (IL)-4 were maintained at >50 microg/ml for 7 days after transplantation in rats treated with CTLA4IgG but <15 microg/ml in control rats. IL-2 concentration was reduced to half in CTLA4IgG-treated rats compared with that in control recipients. Serum IFN-gamma in CTLA4IgG-treated recipients increased after transplantation and was not distinguishable from that of control recipients during the first 7 days after transplantation. Conclusion. We demonstrated that CTLA4IgG treatment alone for 7 days induced a long-term donor specific tolerance in rat allogeneic small bowel transplantation. The induction of long-term acceptance of small bowel allografts by CTLA4IgG is not caused by simply the shift of anti-alloimmune responses from Thl to Th2 cytokine production.     

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.     

Zoom endoscopic monitoring of small bowel allograft rejection

Background The small bowel has been successfully transplanted in patients with irreversible intestinal failure. This report aims to describe endoscopic monitoring of small bowel rejection. Methods A magnification endoscope (zoom endoscope) was used in this study. In the first part of the study (October 1998 to March 2000, 271 endoscopy sessions), the specific endoscopic findings that correlated with rejection were determined. An analysis then was performed on data from the second period (March 2001 to November 2002, 499 sessions) to evaluate the zoom endoscope’s accuracy in monitoring rejection. Results Specific endoscopic findings of rejection found in the first period included background erythema, villous congestion, blunted villous tip, and shortened villous height. When the rejection was successfully treated, endoscopic appearance returned to normal. On the basis of these findings, five endoscopic criteria (villous shortening, villous blunting, background erythema, villous congestion, and mucosal friability) were used to score endoscopic sessions in the second period. Endoscopic diagnosis of rejection was compared with histology. Adult patients showed a sensitivity of 45%, a specificity of 98%, a positive predictive value of 82%, and a negative predictive value of 88%. In pediatric patients, these values were, respectively, 61%, 84%, 57%, and 86%. On 59 distinct occasions (30 in period 1 and 29 in period 2) in which the results were endoscopy negative yet biopsy positive (mild) for rejection, we elected not to treat these rejections on the basis of clinical evaluation, and 58 (98%) resolved without further therapy. Conclusions With the use of magnification, endoscopy is a useful tool for monitoring acute rejection in the small bowel allograft. Part of this work was presented during the annual meeting of the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES), 29 March to 1 April 2000, Atlanta, GA.