小肠移植排斥反应期移植肠粘膜细胞凋亡的研究

目的 明确移植肠上皮细胞凋亡在小肠移植排斥反应中的意义及诊断价值。方法 选用近交系大鼠Ｆ３４４／Ｎ和Ｗｉｓｔａｒ／Ａ进行全小肠异位移植,实验分４组。第１组：非基本对照 ;第２组;同基因移植组;第３组;异基因移植组;第４组;异基因移植加环孢霉素Ａ治疗组。术的第３、５、７天取移植肠进行病理学检查,采用ＴｄＴ介导的脱氧核苷酸原位末端标记法（ＴＵＮＥＬ）检测移植肠上皮细胞凋亡。结果 病理学检查显示第３组大     

Characterization of immune responses in different lymphoid compartments during small intestinal allograft rejection

In the present study, we examined the sequential changes of procoagulant activity (PCA) in different host and graft tissue compartments in order to assess its role as an immunologic effector and monitor of the rejection process. An early increase in PCA in the graft mesenteric nodes marks the onset of the host-graft immune interaction prior to any PCA or histologic changes in the other tissue compartments. This was followed by increases in PCA in the peripheral blood and graft intraepithelial compartments coinciding with maximal clinical and histologic signs of rejection. Cyclosporin A fully suppressed alloantigen-induced activation of PCA in the intraepithelial compartment and peripheral blood mononuclear cells, but only partially suppressed PCA in graft mesenteric nodes of the allogeneic transplants. The sequence of PCA changes accurately reflected the clinical and histologic changes during allograft rejection. Thus, PCA measured in peripheral blood mononuclear cells appears to be a sensitive and accurate marker of allograft rejection.     

Quantitative analysis of cardiac 3-L-nitrotyrosine during acute allograft rejection in an experimental heart transplantation

BACKGROUND: Recent studies have shown that nitric oxide interacts with superoxide to form peroxynitrite, a potent oxidant that modifies cellular proteins producing 3-L-nitrotyrosine (N-Tyr). This study was designed to evaluate N-Tyr quantitatively with high-performance liquid chromatography (HPLC) during cardiac allograft rejection. METHODS: Rat transplanted hearts (allogeneic or syngeneic grafts) were examined with HPLC analysis, immunohistochemistry for N-Tyr, and histological studies on 0, 1, 3, and 7 days after transplantation. RESULTS: No histological rejection was found in syngeneic grafts, or day 0 or 1 allografts. HPLC demonstrated that N-Tyr in allografts increased on day 1 and continued to increase through day 7, while N-Tyr was not detected in any syngeneic grafts. Immunostaining of the allografts did not show N-Tyr on day 1. CONCLUSION: These results demonstrate that N-Tyr shows a time-dependent accumulation in cardiac allografts during acute rejection. N-Tyr detection using HPLC may be an useful maker for early diagnosis of acute rejection before pathological rejection occurs.     

Patchy distribution of rejection changes in small intestinal transplantation.

The aim of this study is to determine the distribution of histological changes of rejection in small intestinal transplantation. Thirty-nine rats were randomized into two groups: group I (n = 15), syngeneic transplants and group II (n = 24), allogeneic transplants. Grafts were excised and examined on days 2, 4, and 8 after transplantation. All grafts of the syngeneic group showed normal mucosa by day 4. However, by this time, all grafts of the allogeneic group demonstrated rejection changes with a patchy distribution in the mucosa. Therefore, with a biopsy from the stoma site there is a risk of missing early rejection.     

Sirolimus attenuates chronic allograft nephropathy in an experimental rat kidney transplantation model

Chronic allograft nephropathy (CAN) is the primary reason for late allograft loss in kidney transplantation. The use of calcineurin inhibitors is suggested to be a risk factor for the development of CAN. Thus, calcineurin-inhibitor-free immunosuppressive protocols are needed to improve long-term graft outcome. Sirolimus affects the immune response by interfering with postreceptor interleukin-2 signaling. Safety profile of sirolimus is different from that of calcineurin inhibitors. We investigated the long-term effects of sirolimus on kidney allografts and fibrogenic growth factor expression and compared it to cyclosporine A. Kidney transplantations were performed from DA to WF rats and syngenic controls were done between DA rats. Allograft recipients were immunosuppressed daily with sirolimus 2 p.o. or CsA 1.5 mg/kg s.c. In addition, sirolimus-treated animals were treated with cyclosporine 1.5 mg/kg s.c. for the first 7 days after transplantation. Serum creatinine levels were measured once a week. Grafts were harvested 90 days after transplantation for histology and immunohistochemistry. Histological changes were scored according to the chronic allograft damage index (CADI). No signs of CAN were seen in syngenic grafts, CADI 0.8 +/- 0.2 (mean +/- SEM). In cyclosporine-treated allografts moderate to intense chronic changes were seen; CADI 10.3 +/- 0.6. Sirolimus significantly ameliorated the development of CAN compared to cyclosporine, CADI 3.0 +/- 0.5 (P < .05). Creatinine values of sirolimus-treated allografts were lower compared to the cyclosporine-treated allografts and were nearly similar to the syngenic grafts. Our results demonstrate that sirolimus attenuates the development of CAN and restores kidney function. Based on our findings, sirolimus improves the long-term kidney graft outcome.     

Early indicators of allograft rejection in a porcine pancreatic transplantation model

Urine cytology and blood lymphocyte blastogenesis were evaluated as indicators of allograft rejection in a porcine pancreatic transplantation model. The percentage of activated lymphocytes and/or blasts was significantly increased during the rejection phase. Positive cytology was present in all rejection episodes. An increased thymidine uptake of blood lymphocytes and a decreased uridine/thymidine uptake quotient were seen prior to the onset of rejection. The reported dissociation of anionic and cationic trypsin levels in serum and urine after transplantation was not seen after simple urinary diversion of the pancreatic juice. This supports the hypothesis that a decreased synthesis of cationic trypsinogen compared with anionic trypsinogen occurs after porcine pancreatic transplantation.     

FK778 does not impair intestinal allograft absorption in a preclinical model of total small bowel transplantation

Malononitrilamide 715 (FK778), a new low-molecular weight immunosuppressant, inhibits both T-cell and B-cell function by acting on the pathway for de novo pyrimidine biosynthesis. Pyrimidines are important for intestinal trophism; their inhibition may predispose to metabolic and functional impairments, such as diarrhea and malabsorption. In this study we assessed the absorptive capacity of intestinal allografts in a large-animal model of small bowel transplantation (SBTx) in pigs chronically treated with FK778. Ten outbred pigs underwent total orthotopic SBTx. Immunosuppression consisted of oral tacrolimus (trough levels 5-15 ng/mL) and oral FK778 (4 mg/kg per day) administered for 60 days. The D-xylose absorption test was performed at day 60 to evaluate carbohydrate absorption. Results were compared to normal controls. Eight of the 10 animals were alive and in good condition at day 60. All of their allografts were free of rejection. The animals had a mean maximal weight loss of 6.4% during the study period; the final weight was comparable to the initial weight (P > .05). Diarrhea was present in all animals (mean 16% of postoperative days). The D-xylose curves showed that absorption in the transplanted animals at day 60 was similar to that in the untreated controls (P > .05). The absence of differences was confirmed by the statistical analysis. In conclusion, our preclinical study in pigs showed that chronic treatment with FK778 in combination with tacrolimus did not impair carbohydrate absorption by the allograft after SBTx.     

Steroid-resistant acute allograft rejection in renal transplantation

Steroid-resistant rejection after pediatric renal transplantation forms a rare but severe complication with a guarded prognosis particularly if this occurs late after transplantation. There is a paucity of data on how to manage these challenging rejection episodes, particularly in the pediatric literature. Mohan Shenoy et al. published a case series of 15 patients who were treated with anti-thymocyte globulin for steroid-resistant acute allograft rejection over a 15-year period in a single center in this issue of Pediatric Nephrology. While the results for the early rejection group were encouraging, the results in the eight patients with late rejection episodes after transplantation were unfavorable and afflicted with a high incidence of side-effects. Important diagnostic tools such as C4d staining of the renal transplant biopsy and the measurement of donor-specific antibodies were underutilized. The editorial reviews the importance of the differentiation between humoral and cellular rejection and the challenges of treating late antibody-mediated acute rejection in these patients. A multi-center approach is required to establish a registry of these events and ideally prospective randomized interventions should be designed to provide some evidence base for the management of this challenging complication after pediatric renal transplantation.     

Difficulties,guidelines and review of developing an acute rejection model after rat intestinal transplantation

Experimental small bowel transplantation (SBT) in rats has been proven to be a useful tool for the study of ischemia-reperfusion and immunological aspects related to solid organ transplantation. However, the model is not completely refined, specialized literature is scarce and complex technical details are typically omitted or confusing. Most studies related to acute rejection (AR) use the orthotopic standard, with small sample sizes due to its high mortality, whereas those studying chronic rejection (CR) use the heterotopic standard, which allows longer term survival but does not exactly reflect the human clinical scenario. Various animal strains have been used, and the type of rejection and the timing of its analysis differ among authors. The double purpose of this study was to develop an improved unusual AR model of SBT using the heterotopic technique, and to elaborate a guide useful to implement experimental models for studying AR. We analyzed the model's technical details and expected difficulties in overcoming the learning curve for such a complex microsurgical model, identifying the potential problem areas and providing a step-by-step protocol and reference guide for future surgeons interested in the topic. We also discuss the historic and more recent options in the literature.     

Effect of orthotopic small bowel transplantation on mineral metabolism in an experimental model

BACKGROUND: Numerous experimental models have been described for investigation of short bowel syndrome. The aim of this study was to examine the effect of orthotopic small bowel transplantation (OSBT) on universal metabolism in an inbred rat model, with particular emphasis on mineral metabolism. METHODS: Jejunoileal resection and syngeneic OSBT was performed in 12-week-old male Lewis rats. Metabolic studies were performed over the following 16 weeks. Bones were analysed by physicochemical methods, dual X-ray absorptiometry, biomechanical procedures and histomorphometry. Biochemical markers of bone turnover were also measured. RESULTS: Jejunoileal resection induced severe short bowel syndrome with profoundly reduced food efficiency, bone size, fracturing energy and bone mineral content, but no cancellous bone osteopenia. After OSBT rats showed normal growth; bones were of normal size, and bone mineral content and fracturing energy were similar to those in sham-operated controls. However, tibial, but not vertebral, cancellous bone osteopenia was found after transplantation. CONCLUSION: OSBT with portal venous drainage achieves almost optimal mineral and bone metabolism. In the absence of immunosuppressive therapy, OSBT does not appear to have major untoward side-effects on bone in rats.     

小肠移植急性排斥反应期移植肠白细胞介素2受体和细胞间粘附分子1的表达

目的　探讨移植肠白细胞介素２ 受体（ Ｉ Ｌ２ Ｒ） 和细胞间粘附分子１（ Ｉ Ｃ Ａ Ｍ１） 的表达在小肠移植排斥反应中的意义及诊断价值。方法　选用近交系大鼠 Ｆ３４４／ Ｎ 和 Ｗｉｓｔａｒ／ Ａ 进行全小肠异位移植,实验分４ 组,第１ 组： Ｗｉｓｔａｒ;第２ 组： Ｗｉｓｔａｒ→ Ｗｉｓｔａｒ ;第３ 组： Ｆ３４４ → Ｗｉｓｔａｒ;第４ 组： Ｆ３４４ → Ｗｉｓｔａｒ＋环孢霉素 Ａ（６ ｍｇ·ｋｇ － １·ｄ － １） 。术后第３ 、５ 、７ 天取各组动物移植肠标本进行病理学检查,应用免疫组化技术（ Ｓ Ｐ 法） 检测移植肠 Ｉ Ｌ２ Ｒ 和 Ｉ Ｃ Ａ Ｍ１ 的表达。结果　病理学检查显示第３ 组大鼠在术后第３ 、５ 、７天分别符合轻、中、重度排斥,第２ 、４ 组无明显排斥征象。第３ 组 Ｉ Ｌ２ Ｒ 表达在术后均非常显著高于其他３ 个对照组;第３ 组 Ｉ Ｃ Ａ Ｍ１ 表达在术后第３ 、５ 天较相似,尤其在上皮细胞表现为强阳性,并显著高于第１ 组。但第２ 、４ 对照组 Ｉ Ｃ Ａ Ｍ１ 表达也较高,第３ 组仅在术后第３ 天 Ｉ Ｃ Ａ Ｍ１ 评分显著高于第２ 组。结论　 Ｉ Ｌ２ Ｒ 和 Ｉ Ｃ Ａ Ｍ１ 阳性细胞在小肠移植排斥反应过程中发挥重要作用。应用单克隆抗体阻