Immunomodulation for intestinal transplantation by allograft irradiation, adjunct donor bone marrow infusion, or both

Donor's graft ex vivo T-cell depletion with fludarabine reduces graft-versus-host disease signs and improves survival after intestinal transplantation - an experimental study

Intestinal passenger T leukocytes are responsible for graft-versus-host disease (GvHD) in intestinal transplantation (ITx). We hypothesized that ex vivo fludarabine treatment of the bowel graft would diminish the risk of GvHD and improve overall survival post-transplant. We performed isolated heterotopic small bowel transplantations from Lewis (LEW) to Brown Norway (BN) rat strains, which generated GvHD signs from the fourth day post-transplant. These symptoms included rash, weight loss, piloerection, and diarrhea. The grafts of one of the experimental groups were immersed and sealed in cold Celsior preservation solution with 1000 µm fludarabine for 1 h, prior to its implantation into recipient animals. No histological signs of intestinal tissue alterations were observed after fludarabine treatment. Fludarabine-treated bowel recipients showed significantly later and milder clinical signs of GvHD and reduced total donor cell chimerism, as determined by flow cytometry using strain-specific anti-HLA antibodies. Additionally, fludarabine treatment prolonged recipients' overall survival (13.5 days ± 0.3 days vs. 9.2 days ± 0.5). We conclude that active modification of the intestinal leukocyte composition is advantageous in our ITx animal model. Immunosuppression with fludarabine during the surgical procedure, which could be translated directly to the clinic, protects bowel recipients from GvHD and improves overall post-transplant survival.

Update on Chronic Rejection After Intestinal Transplant: An Overview From Experimental Settings to Clinical Outcomes

Chronic rejection affects the long-term survival of solid-organ transplants, accounting for an incidence of between 5% and 10% after intestinal/multivisceral transplant. Because of unclear symptoms and signs and endoscopic findings, the diagnosis is often delayed. Presently, allograft removal represents the only available therapy due to the absence of effective pharmacologic approaches. Extensive research, through animal models, has been performed over the past 20 years to clarify the complex immune- and nonimmune-mediated mechanisms behind the development of chronic allograft enteropathy, with the aim of elucidating how to avert chronic rejection. The role of donor-specific antibodies and the way to challenge them in the clinic have gained acceptance among transplant centers as one of the main steps to prevent chronic rejection, although no common protocol exists that can be applied in a systematic fashion. The adjunct of a liver graft when retrans planting is needed in a sensitized recipient due to its protective effect against humoral immunity. Multicenter studies and clinical trials are required to better understand the pathogenesis of chronic rejection and to find the therapeutic answer to this clinical query.

The Ex Vivo Time of Fresh Autologous Cartilage Before Transplantation and Cartilage Absorption Degree

OBJECTIVE

This study aims to determine the relationship between the time of autogenous cartilage in vitro and the degree of absorption in animal experiments.

METHODS

New Zealand white rabbits were randomly divided into 3 groups according to the time of cartilage in vitro: 1-hour group, 2-hour group, and 3-hour group. A volume of ear cartilage was taken and transplanted into the back, according to the group. After 1 month, the volume was taken out and remeasured. Then, these were compared by scanning electron microscopy and hematoxylin and eosin staining.

RESULTS

The cartilage bulk absorption level of different groups is different (P < 0.05). There was statistical significance when the 3-hour group was compared with the other 2 groups (P < 0.05). This shows that cartilage volume absorption level becomes higher after 3 hours. Scanning electron microscopy revealed that before and after transplantation, the arrangement of collagen fibers and the gap between these fibers changed. Hematoxylin and eosin staining revealed that there were some morphological changes in chondrocytes, and the degree of chondrocyte apoptosis increased with time, which was accompanied by granulation tissue formation. In addition, the cartilage tissue survived after transplantation.

CONCLUSION

The change in cartilage volume was more obvious after 3 hours of autogenous fresh cartilage transplantation, when compared with that of the first 2 hours. The longer the time of light microscopy was, the longer the apoptosis of cartilage cells, the more serious the destruction of collagen fibers and the cartilage matrix, and the greater the absorption of cartilage and the new chondrocytes.

The Leuven Immunomodulatory Protocol Promotes T-Regulatory Cells and Substantially Prolongs Survival After First Intestinal Transplantation

Intestinal transplantation (ITx) remains challenged by frequent/severe rejections and immunosuppression-related complications (infections/malignancies/drug toxicity). We developed the Leuven Immunomodulatory Protocol (LIP) in the lab and translated it to the clinics. LIP consists of experimentally proven maneuvers, destined to promote T-regulatory (Tregs)-dependent graft-protective mechanisms: donor-specific blood transfusion (DSBT); avoiding high-dose steroids/calcineurin-inhibitors; and minimizing reperfusion injury and endotoxin translocation. LIP was tested in 13 consecutive ITx from deceased donors (2000-2014) (observational cohort study). Recipient age was 37 years (2.8-57 years). Five-year graft/patient survival was 92%. One patient died at 9 months due to aspergillosis, another at 12 years due to nonsteroidal anti-inflammatory drug-induced enteropathy. Early acute rejection (AR) developed in two (15%); late AR in three (23%); all were reversible. No chronic rejection (CR) occurred. No malignancies developed and estimated glomerular filtration rate remained stable post-Tx. At last follow-up (3.5 years [0.5-12.5 years]), no donor-specific antibodies were detected and 11 survivors were total parenteral nutrition free with a Karnofsky score >90% in 8 recipients (follow-up >1 years). A high frequency of circulating CD4⁺ CD45RA^- Foxp3^hi memory Tregs was found (1.8% [1.39-2.21]), comparable to tolerant kidney transplant (KTx) recipients and superior to stable immunosuppression (IS)-KTx, KTx with CR, and healthy volunteers. In this ITx cohort we show that DSBT in a low-inflammatory/pro-regulatory environment activates Tregs at levels similar to tolerant-KTx, without causing sensitization. LIP limits rejection under reduced IS and thereby prolongs long-term survival to an extent not previously attained after ITx.

Immunosuppressant Strategies for Intestinal Transplantation: A Review of a Tolerogenic Regimen

Intestinal, combined liver-intestinal, and multivisceral transplantation are now considered the standard of care for children and adults with permanent intestinal failure. Early attempts at intestinal transplantation were discouraging because of the high incidence of technical complications, rejection, and infection. Advances in the field of transplantation, including the introduction of tacrolimus, improved surgical techniques, and improvements in postoperative care, have led to a renewed interest in intestinal transplantation since 1990. The most significant achievement, however, has been the effective control of rejection and life-threatening infections. This article focuses on the experience to date of innovative strategies that induce lymphocyte depletion and reduction in the incidence of rejection. In this setting, low-maintenance immunosuppression is clinically achievable with an acceptable rate of allograft rejection. Subsequently, the long-term complications of immunosuppression are significantly reduced with achievement of better long-term survival, and an overall improvement in the quality of life.

Attempted depletion of passenger leukocytes by irradiation in pigs

Allograft/xenograft rejection is associated with “passenger leukocyte” migration from the organ into recipient lymph nodes. In Study 1, we attempted to deplete leukocytes from potential kidney “donor” pigs, using two regimens of total body irradiation. A dose of 700 cGy was administered, followed by either 800 cGy (“low-dose”) or 1,300 cGy (“high dose”) with the kidneys shielded. Neither regimen was entirely successful in depleting all leukocytes, although remaining T and 8 cell numbers were negligible. Study 2 was aimed at providing an indication of whether near-complete depletion of leukocytes had any major impact on kidney allograft survival. In non-immunosuppressed recipient pigs, survival of a kidney from a donor that received high-dose irradiation was compared with that of a kidney taken from a non-irradiated donor. Kidney graft survival was 9 and 7 days, respectively, suggesting that depletion had little impact on graft survival. The lack of effect may have been related to (i) inadequate depletion of passenger leukocytes, thus not preventing a direct T cell response, (ii) the presence of dead or dying leukocytes (antigens), thus not preventing an indirect T cell response, or (iii) constitutive expression of MHC class II and B7 molecules on the porcine vascular endothelium, activating recipient T cells.

Development and validation of a procedure to isolate viable bone marrow cells from the vertebrae of cadaveric organ donors for composite organ grafting

BACKGROUND AIMS

Donor-derived vertebral bone marrow (BM) has been proposed to promote chimerism in solid organ transplantation with cadaveric organs. Reports of successful weaning from immunosuppression in patients receiving directed donor transplants in combination with donor BM or blood cells and novel peri-transplant immunosuppression has renewed interest in implementing similar protocols with cadaveric organs.

METHODS

We performed six pre-clinical full-scale separations to adapt vertebral BM preparations to a good manufacturing practice (GMP) environment. Vertebral bodies L4-T8 were transported to a class 10 000 clean room, cleaned of soft tissue, divided and crushed in a prototype bone grinder. Bone fragments were irrigated with medium containing saline, albumin, DNAse and gentamicin, and strained through stainless steel sieves. Additional cells were eluted after two rounds of agitation using a prototype BM tumbler.

RESULTS

The majority of recovered cells (70.9 ± 14.1%, mean ± SD) were eluted directly from the crushed bone, whereas 22.3% and 5.9% were eluted after the first and second rounds of tumbling, respectively. Cells were pooled and filtered (500, 200 μm) using a BM collection kit. Larger lumbar vertebrae yielded about 1.6 times the cells of thoracic vertebrae. The average product yielded 5.2 ± 1.2 × 10(10) total cells, 6.2 ± 2.2 × 10(8) of which were CD45(+) CD34(+). Viability was 96.6 ± 1.9% and 99.1 ± 0.8%, respectively. Multicolor flow cytometry revealed distinct populations of CD34(+) CD90(+) CD117(dim) hematopoietic stem cells (15.5 ± 7.5% of the CD34 (+) cells) and CD45(-) CD73(+) CD105(+) mesenchymal stromal cells (0.04 ± 0.04% of the total cells).

CONCLUSIONS

This procedure can be used to prepare clinical-grade cells suitable for use in human allotransplantation in a GMP environment.

Fish oil enhances recovery of intestinal microbiota and epithelial integrity in chronic rejection of intestinal transplant

Background

The intestinal chronic rejection (CR) is the major limitation to long-term survival of transplanted organs. This study aimed to investigate the interaction between intestinal microbiota and epithelial integrity in chronic rejection of intestinal transplantation, and to find out whether fish oil enhances recovery of intestinal microbiota and epithelial integrity.

Methods/Principal Findings

The luminal and mucosal microbiota composition of CR rats were characterized by DGGE analysis at 190 days after intestinal transplant. The specific bacterial species were determined by sequence analysis. Furthermore, changes in the localization of intestinal TJ proteins were examined by immunofluorescent staining. PCR-DGGE analysis revealed that gut microbiota in CR rats had a shift towards Escherichia coli, Bacteroides spp and Clostridium spp and a decrease in the abundance of Lactobacillales bacteria in the intestines. Fish oil supplementation could enhance the recovery of gut microbiota, showing a significant decrease of gut bacterial proportions of E. coli and Bacteroides spp and an increase of Lactobacillales spp. In addition, CR rats showed pronounced alteration of tight junction, depicted by marked changes in epithelial cell ultrastructure and redistribution of occuldin and claudins as well as disruption in TJ barrier function. Fish oil administration ameliorated disruption of epithelial integrity in CR, which was associated with an improvement of the mucosal structure leading to improved tight junctions.

Conclusions/Significance

Our study have presented novel evidence that fish oil is involved in the maintenance of epithelial TJ integrity and recovery of gut microbiota, which may have therapeutic potential against CR in intestinal transplantation.

Immunologic aspects and rejection in solid organ versus reconstructive transplantation

The immunosuppressive medications developed over the past 3 decades have paved the way for solid organ transplantation to become the treatment of choice for end-stage organ failure. At the end of the century, composite tissue transplantation in humans was performed with success using the same immunosuppressive medications and therapeutic principles. A decade later, experience from >100 cases of reconstructive transplantation have increased the knowledge, changed the view, and affected the therapeutic principles in this novel field. We herein portray the evolution of this novel type of transplant with particular reference to immunologic aspects, particularly differences between reconstructive and solid organ transplantation.

Influence of immunosuppression on alloresponse, inflammation and contractile function of graft after intestinal transplantation

In small bowel transplantation (SBTx), graft manipulation, ischemia/reperfusion injury and acute rejection initiate a severe cellular and molecular inflammatory response in the muscularis propria leading to impaired motility of the graft. This study examined and compared the effect of tacrolimus and sirolimus on inflammation in graft muscularis. After allogeneic orthotopic SBTx, recipient rats were treated with tacrolimus or sirolimus. Tacrolimus and sirolimus attenuated neutrophilic, macrophage and T-cell infiltration in graft muscularis, which was associated with reduced apoptotic cell death. Nonspecific inflammatory mediators (IL-6, MCP-1) and T-cell activation markers (IL-2, IFN-gamma) were highly upregulated in allogeneic control graft muscularis 24 h and 7 days after SBTx, and tacrolimus and sirolimus significantly suppressed upregulation of these mediators. In vitro organ bath method demonstrated a severe decrease in graft smooth muscle contractility in allogeneic control (22% of normal control). Correlating with attenuated upregulation of iNOS, tacrolimus and sirolimus treatment significantly improved contractility (64% and 72%, respectively). Although sirolimus reduced cellular and molecular inflammatory response more efficiently after 24 h, contrary tacrolimus prevented acute rejection more efficiently. In conclusion, tacrolimus and sirolimus attenuate cellular and molecular inflammatory response in graft muscularis and subsequent dysmotility of the graft after allogeneic SBTx.

Lymphoproliferative disorders and de novo malignancies in intestinal and multivisceral recipients: improved outcomes with new outlooks

BACKGROUND

Early experience with intestinal and multivisceral transplantation was plagued with high risk of rejection and posttransplant lymphoproliferative disorders (PTLD). To improve outcome, innovative management and immunosuppressant strategies were sequentially evolved.

METHODS

With initiation of the program in 1990, serial monitoring of Epstein-Barr-Viral load was introduced in 1994 with adoption of preemptive antiviral therapy. In 1995, cyclophosphamide or daclizumab induction was added to the tacrolimus-steroid-based multiple drug immunosuppressions. Such a conventional approach was replaced in 2001 with a novel immunosuppressive protocol consisting of recipient pretreatment with a single dose of rabbit antithymocyte globulin or alemtuzumab and posttransplant tacrolimus monotherapy.

RESULTS

With a total of 395 consecutive primary recipients, de novo malignancy(s) developed in 61 (15%) patients, with PTLD in 52 (13%), and nonlymphoid cancer (NLC) in 13 (3.2%). Malignancy was donor driven in 3 (4.6%) recipients and associated with graft-versus-host disease in 7 (11.4%). Children were at a significantly higher risk (P<0.001) of PTLD, and adults were more vulnerable (P=0.01) to NLC. With multivariate analyses, type of immunosuppression, recipient age, splenectomy, and treatment of rejection were significant PTLD risk factors.

CONCLUSIONS

Despite pretransplant lymphoid depletion, preemptive antiviral therapy and minimization of posttransplant immunosuppression significantly reduced PTLD morbidity (P=0.0001) and mortality (P=0.001) with no impact on NLC. Patient survival was also improved (P=0.0001) with 91% at 1 year and 75% at 5 years.

Evolution of the immunosuppressive strategies for the intestinal and multivisceral recipients with special reference to allograft immunity and achievement of partial tolerance

Introduction of new innovative immunosuppressive strategies has been the milestone of the recent evolution of intestinal and multivisceral transplantation. With new insights into the mechanisms of organ engraftment and acquired tolerance, the Pittsburgh tolerogenic protocol was recently introduced and consisted of two main therapeutic principles: recipient pretreatment with lymphoid ablating antibodies and minimal post-transplant immunosuppression with tacrolimus monotherapy. The reported herein improved survival and the striking ability to wean immunosuppression among the intestinal and multivisceral recipients pretreated with a single-dose of Thymoglobulin (rATG) or Campath-1H (alemtuzumab) supports our working hypothesis with successful induction of variable tolerance. It is important, however, that careful monitoring of subtle histologic changes in serial endoscopic-guided mucosal biopsies be carried out for early diagnosis of allograft immune activation with prompt restoration of the baseline immunosuppressive therapy. Future scientific discoveries with better understanding of the mechanisms of immune tolerance and clinical introduction of reliable assays will increase the chance and safety of achieving complete tolerance among the intestinal and other solid organ recipients. This review will focus on the historic evolution of the immunosuppressive and other management strategies utilized for the intestinal and multivisceral recipients at the University of Pittsburgh with special reference to allograft immunity and the successful achievement of partial tolerance.

A national conference to determine research priorities in pediatric solid organ transplantation

The need for evidence-based practice guidelines requires high quality, carefully controlled clinical research trials. This multidisciplinary conference attempted to: identify urgent clinical and research issues, identify obstacles to performing clinical trials, develop concepts for organ-specific and all-organ research and generate a report that would serve as a blueprint for future research initiatives. A few themes became evident. First, young children present a unique immunologic environment which may lead to tolerance, therefore, including young children in immunosuppression withdrawal and tolerance trials may increase the potential benefits of these studies. Second, adolescence poses significant barriers to successful transplantation. Non-adherence may be insufficient to explain poorer outcomes. More studies focused on identification and prevention of non-adherence, and the potential effects of puberty are required. Third, the relatively naive immune system of the child presents a unique opportunity to study primary infections and alloimmune responses. Finally, relatively small numbers of transplants performed in pediatric centers mandate multicenter collaboration. Investment in registries, tissue and DNA repositories will enhance productivity. The past decade has proven that outcomes after pediatric transplantation can be comparable to adults. The pediatric community now has the opportunity to design and complete studies that enhance outcomes for all transplant recipients.

Chimerism and bone marrow based therapies in transplantation

Composite tissue allotransplantation holds a great potential for providing increased knowledge of anatomy and microsurgical experience for life-enhancing reconstructions. Many transplant cases around the world have made this a clinical reality at the present time. Composite tissue allotransplants contain multiple tissue types, including bone, muscle, vessels, nerves, skin, and immune cells and bear a huge antigenic load. Although immunosuppressive drugs are applied successfully to prevent allograft rejection, their side effects pose a barrier to worldwide use. Bone marrow therapy in many tolerance induction protocols, therefore, provides a guide to reaching the target of permanent immunotolerance. Multiple studies suggest that bone marrow is immunomodulatory and may facilitate allograft acceptance. In this review, bone marrow based therapy protocols of clinical and experimental models are presented in two major categories: solid organ and composite tissue transplantation.

Simultaneous bone marrow and intestine transplantation promotes marrow-derived hematopoietic stem cell engraftment and chimerism

Organ allografts have been shown to provide a syngeneic microenvironment for organ-based donor hematopoietic stem cells to maintain long-lasting chimerism after transplantation. We hypothesized that organ allografts would also support engraftment and hematopoiesis of adjunctively infused donor marrow stem cells, syngeneic to organ grafts, in nonmyeloablated recipients. In BN-to-LEW and GFP-to-ACI rat combinations, donor bone marrow (BM) infusion together with small intestine transplantation (SITx) under short-course tacrolimus immunosuppression resulted in persistent macrochimerism (more than 5%) for 150 days. In contrast, after BM infusion or SITx alone, chimerism was temporary and disappeared by day 100. Y-chromosome polymerase chain reaction (PCR) in sex-mismatched male BM plus female intestine or female BM plus male intestine transplantation into female recipients suggested that persistent macrochimerism was derived from infused BM. BM infusion together with lymphoid-depleted intestine grafts also supported macrochimerism development; however, third-party intestine grafts did not. After GFP-positive BM plus wild-type (WT) SITx into ACI, large numbers of GFP-positive leukocytes were found in WT intestine grafts. Isolated cells from WT intestine grafts developed GFP-positive CFU-Cs and propagated multilineage GFP-positive leukocytes when adoptively transferred into lethally irradiated WT recipients. These findings suggest that intestine allograft supports simultaneously infused donor (syngeneic to organ grafts) marrow stem cell engraftment, differentiation, and persistence of chimerism.

Intestinal transplantation: an update

PURPOSE OF REVIEW

As outcomes with intestinal transplantation continue to improve, its role in the management of intestinal failure patients becomes clearer. Some intestinal failure patients do well with long-term total parenteral nutrition (TPN), while others develop life-threatening complications and need to be evaluated for intestinal transplants (ITs). The purpose of this review is to update the current status of intestinal transplantation and its role in the management of intestinal failure patients.

RECENT FINDINGS

Current outcomes indicate that intestinal transplants should be considered earlier in intestinal failure patients that develop liver injury, to prevent irreversible liver disease that would mandate a simultaneous liver transplant. Due to the small bowel (SB) graft's unique immunobiologic features, it is especially challenging to transplant successfully. Although new immunosuppressive strategies have been developed that appear to improve short-term results, their impact on long-term outcomes has yet to be shown. A better understanding of the interactions that occur between the SB's inherent immune system and its luminal flora may be required to devise strategies that will significantly curtail the SB graft's immunogenicity.

SUMMARY

Intestinal transplantation remains a significant challenge. Ongoing efforts to better define the parameters that best predict total parenteral nutrition failure and the unique mechanisms that influence small bowel allograft outcomes are necessary before a broader application of small bowel transplantation can be indicated.

[Apoptosis participation in the acute rejection of intestinal transplantation in rats]

BACKGROUND

Intestinal transplantation is a possible treatment for patients with short bowel syndrome, aiming the reintroduction of oral diet. However, the major obstacle in this procedure is the strong rejection. Delay in rejection diagnosis may be irreversible and lethal.

AIM

To define method for early diagnosis of rejection based on the apoptosis from intestinal allograft.

MATERIAL AND METHODS

Isogenic rats Brown-Norway (BN) and Lewis (LEW) were submitted to intestinal heterotopic allotransplantation and divided in two groups: LEW donor to LEW recipient isograft group C and BN donor to LEW recipient allograft group (Tx). According to the day of sacrifice, Tx group were subdivided in three subgroups with eight animals each as follow: Tx3-- sacrificed at third postoperative day (POD), Tx5 -- sacrificed at fifth POD and Tx7 -- sacrificed at seventh POD. Eight animals from control group were subdivided in three moments according to the time of biopsy from the graft as follow: C3 -- biopsy at third POD; C5 -- biopsy at fifth POD and C7 -- biopsy at seventh POD. All animals from control group were sacrificed at seventh POD. Rejection parameters were compared between the control groups (C3 vs C5, C3 vs C7 and C5 vs C7, and allograft group (Tx3 vs Tx5, Tx3 vs Tx7 and Tx5 vs Tx7). The same parameters were analyzed between the control group and allograft groups ( C3 vs Tx3, C5 vs Tx5 and C7 vs Tx7). In C group no statistical significant difference regarding the expression of the apoptotic cells were detected, while in Tx group, the presence of apoptotic cells were remarkable since the third postoperative day.

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.

[Cytokine participation in the acute rejection of intestinal transplantation in rats]

BACKGROUND

Intestinal transplantation is a possible treatment for patients with short bowel syndrome, aiming the reintroduction of oral diet. However, the major obstacle in this procedure is the strong rejection. Delay in rejection diagnosis may be irreversible and lethal.

AIM

To define method for early diagnosis of rejection based on the presence of interleucin-6 (IL-6) e interferon- gamma (IFN-gamma) from intestinal allograft.

MATERIAL AND METHODS

Isogenic rats Brown-Norway (BN) and Lewis (LEW) were submitted to intestinal heterotopic allotransplantation and divided in two groups: LEW donor to LEW recipient isograft group (C) and BN donor to LEW recipient allograft group (Tx). According to the day of sacrifice, Tx group were subdivided in three subgroups with eight animals each as follow: Tx3--sacrificed at third postoperative day (POD), Tx5--sacrificed at fifth POD and Tx7--sacrificed at seventh POD. Eight animals from control group were subdivided in three moments according to the time of biopsy from the graft as follow: C3--biopsy at third POD; C5--biopsy at fifth POD and C7--biopsy at seventh POD. All animals from control group were sacrificed at seventh POD. Rejection parameters were compared between the control groups (C3 vs C5, C3 vs C7 and C5 vs C7, and allograft group (Tx3 vs Tx5, Tx3 vs Tx7 and Tx5 vs Tx7). The same parameters were analyzed between the control group and allograft groups (C3 vs Tx3, C5 vs Tx5 and C7 vs Tx7).

RESULTS

In C group no statistical significant difference regarding the immunoexpression of the cytokines, while in Tx group, immunoexpression of IL-6 and IFN-gamma were remarkable since the fifth postoperative day.

Graft versus host disease in intestinal transplantation

Our aim was to analyze the clinical course and outcome of patients with graft vs. host disease (GVHD) after intestinal transplantation (ITx). All patients receiving ITx between May, 1990 and December, 2003 were retrospectively reviewed for evidence of GVHD. Two hundred and fifty patients underwent ITx during the study period. Graft vs. host disease was suspected clinically in 23 patients on the clinical basis of presentation such as skin rash, ulceration of oral mucosa, diarrhea, lymphadenopathy, or native liver dysfunction. Fourteen (eight children and six adults) patients (5.6% of total patient population) had GVHD confirmed by histopathological criteria including keratinocyte necrosis (n = 9), epithelial apoptosis of the native gastrointestinal tract (n = 4), and epithelial cell necrosis of oral mucosa (n = 1). Donor-cell tissue infiltration or extensive peripheral blood donor-cell chimerism was documented on seven occasions. The majority of cases of GVHD resolved with steroid administration and optimization of tacrolimus immunosuppression. The incidence of histologically proven GVHD after clinical intestinal transplantation is 6.5% (8/122) in children and 4.7% (6/128) in adults. Successful clinical management requires a high index of suspicion to minimize morbidity and mortality. Diagnostic and treatment strategies based on this experience are proposed.

Gut failure and abdominal visceral transplantation

Despite the reported high survival with total parenteral nutrition (TPN) therapy for patients with intestinal failure, a considerable number of patients do not escape the potential risks of TPN-associated complications, including hepatic failure, vanishing of central venous access and line sepsis. Thus, intestinal, liver-intestinal and multivisceral transplantation have recently emerged to rescue those who can no longer be maintained on TPN. Before this development, and for nearly three decades, small-bowel transplantation was plagued with uncontrolled rejection, graft v. host disease and fatal infection. These barriers stemmed from the large gut lymphoid mass and heavy microbial load contained in the intestinal lumen. The recent improvement in survival after the clinical introduction of tacrolimus with achievement of full enteric nutritional autonomy qualified the procedure by the US Health Care Financing Administration as the standard of care for patients with intestinal and TPN failure. The decision was supported by a decade of clinical experience with cumulative improvement in patient and graft survival. In addition, the introduction of new effective immunoprophylactic agents and novel therapeutic approaches has contributed to a further increase in the therapeutic advantages of the procedure. The present review article outlines the current clinical practice of intestinal transplantation and defines new management strategies with the aim of raising the level of the procedure to be a better alternative therapy for TPN-dependent patients.

Immune responses of graft mesenteric lymph node in small bowel transplantation

BACKGROUND

The high proportions of lymphoid tissues are thought to be one of the underlying factors inducing severe allograft rejection following small bowel transplantation. Mesenteric lymph nodes (MLN) contained in the intestinal graft are not only a source of donor-derived professional antigen-presenting cells, but also offer a field for immune interaction between donor and host cells. We investigated immune responses in graft MLNs with or without FK506 to develop a novel strategy to control small bowel allograft rejection.

MATERIALS AND METHODS

Heterotopic small bowel transplantations were performed from Brown Norway donors to Lewis recipients. Changes in population of lymphocytes, expressions of costimulatory molecules, apoptosis, and cytokine profiles in graft MLNs were evaluated.

RESULTS

The increase in apoptotic cells and cytokine responses relating to rejection in the graft MLNs developed prior to those in graft jejunum. While donor lymphocytes in graft MLNs were rapidly replaced to host-derived lymphocytes independent of FK treatment, increase in CD8(+) T cells in host population was seen only in recipients without FK506 treatment. The expressions of B7 molecules on donor cells in graft MLNs were significantly lower in the recipients with FK treatment.

CONCLUSIONS

Immune responses in graft MLNs have significant impact on the outcome of the small bowel allograft. Apoptosis of graft MLN cells was well correlated with and ahead of progression of acute rejection. Modulation of costimulatory molecules on donor-derived MLN cells in the allograft and specific suppression of host CD8(+) T cells are possible ways to control severe rejection after allogeneic small bowel transplantation.

Intestinal graft versus native liver cytokine expression in a rat model of intestinal transplantation with and without donor-specific cell augmentation

BACKGROUND

Immunomodulatory strategies such as donor-specific bone marrow or blood transfusions have been used to promote engraftment after intestinal transplants. We previously showed that delivery of donor antigen via the portal vein can effectively reduce the rate of intestinal graft rejection. The purpose of our current study was to investigate the impact of donor-specific cell augmentation (blood versus bone marrow) via the portal vein on cytokine expression in intestinal grafts versus native livers.

MATERIAL AND METHODS

We performed heterotopic small intestinal transplants between male Brown-Norway (donor) and female Lewis (recipient) rats. We studied 10 groups according to the type of donor-specific cell augmentation and the use and dose of immunosuppressive therapy. For cell augmentation, donor-specific blood or bone marrow was transfused via the donor portal vein immediately before graft implantation. For immunosuppression, tacrolimus was used post-transplant at a high or low dose. Control rats received neither immunosuppression nor cell augmentation. Tissue samples for histological assessment were obtained at designated time points. RNA was extracted from intestinal graft and native liver biopsies for cytokine measurements (IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6, IFN-gamma, TNF-alpha, and TNF-beta). Chimerism levels were determined using Q-PCR analysis.

RESULTS

Without concurrent immunosuppression, neither portal donor-specific blood nor bone marrow transfusion reduced the rate of rejection. With immunosuppression, outcome was significantly better after portal donor-specific blood (versus bone marrow) transfusion. Irrespective of the type of donor-specific cell augmentation, severe rejection caused strong cytokine expression in the grafts of IL-1 alpha, IL-1 beta, IFN-gamma, and TNF-alpha; in the native livers, mainly of TNF-alpha (with IFN-gamma showing hardly any increase). In general, rejection caused stronger cytokine expression in the grafts than in the native livers. Mild rejection correlated well with strong intragraft expression of IL-6, TNF-alpha, and TNF-beta (early rejection markers); severe rejection with IL-1 alpha, IL-1 beta, IFN-gamma, and TNF-alpha (late rejection markers). In addition to cell augmentation per se, the type of cell augmentation also had an impact on cytokine expression in both grafts and native livers. Cell-augmented (versus tacrolimus-treated) rats showed hardly any differences in intragraft cytokine expression, but the expression of almost all cytokines was significantly stronger in the native livers. With immunosuppression, bone marrow infusion increased intragraft cytokine expression of IL-1 alpha, IL-1 beta, IFN-gamma, and TNF alpha, as well as liver cytokine expression of IL-1 beta, compared to blood transfusion. This finding reflected the more advanced rejection stages in the bone marrow infused group; different types of donor-specific cell augmentation had similar effects on liver cytokine expression. In the absence of myoablative therapy, chimerism levels were low, in both cell-augmented and non-cell-augmented groups.

CONCLUSIONS

Rejection and donor-specific cell augmentation independently causes differences in intragraft versus native liver cytokine expression after intestinal transplants. Portal donor-specific blood transfusion, as compared with donor-specific bone marrow infusion, lowered the incidence of rejection and diminished intragraft cytokine up-regulation.

Morphology and function of canine small intestinal autografts: with particular interest in the influence of ex vivo graft irradiation

The intestinal transplantation procedure obligates an early functional deficit in intestinal grafts. Graft irradiation has been used to modulate post-transplant immune reactions; however, irradiation may cause further deterioration of the function of the transplanted intestine. Using the canine model, we investigated the influence of the transplant procedures, with and without ex vivo graft irradiation, on early intestinal graft function and histopathology. Outbred hound dogs underwent autointestinal transplantation with (n=8) or without (n=5) 7.5 Gy ex vivo graft irradiation. Mucosal cytochrome P450 and P-glycoprotein, routine immunohistopathology, and intestinal absorptive function were studied. Weight gain was slow after surgery, but was comparable in the irradiated and nonirradiated groups. During the early post-transplant period, both groups showed defects in intestinal absorption, associated with decreased cytochrome P450 3A4 activity and reduced P-glycoprotein expression, regardless of graft irradiation. These changes returned to normal in both groups by day 28. Histopathologically, epithelial apoptosis showed a slight increase 1 hour after transplantation; however, there was no evidence of histopathologic abnormalities including arterial changes associated with irradiation. In addition, the frequency of T and B lymphocytes in the lamina propria were not significantly influenced by the transplant surgery or ex vivo irradiation. Thus, early after transplantation, intestinal function was impaired and effectiveness of orally administered immunosuppressive drugs was significantly altered. Graft irradiation did not induce further defects in intestinal function or cause histopathologic abnormalities.

Transplante de intestino delgado

RACIONAL: Avanços da biotecnologia e o desenvolvimento de novas drogas imunossupressoras melhoraram os resultados do transplante de intestino delgado. Esse transplante é atualmente indicado para casos especiais da falência intestinal. OBJETIVO: A presente revisão realça os recentes desenvolvimentos na área do transplante de intestino delgado. MATERIAL E MÉTODO: Mais de 600 publicações de transplante de intestino delgado foram revisadas. O desenvolvimento da pesquisa, novas estratégias de imunossupressão, monitorização do enxerto e do receptor, e avanços na técnica cirúrgica são discutidos. RESULTADOS: Realizaram-se cerca de 700 transplante de intestino delgado em 55 centros: 44% intestino-fígado, 41% enxerto intestinal isolado e 15% transplante multivisceral. Rejeição e infecção são as principais limitações desse transplante. Sobrevida de 5 anos na experiência internacional é de 46% para o transplante de intestino isolado, 43% para o intestino-fígado e de cerca de 30% para o transplante multivisceral. Sobrevidas prolongadas são mais freqüentes nos centros com maior experiência. Em série de 165 transplantes intestinais na Universidade de Pittsburgh, PA, EUA, foi relatada sobrevida do paciente maior do que 75% no primeiro ano, 54% em 5 anos e 42% em 10 anos. Mais de 90% desses pacientes assumem dieta oral irrestrita. CONCLUSÃO: O transplante de intestino delgado evoluiu de estratégia experimental para uma alternativa viável no tratamento da falência intestinal permanente. Promover o refinamento da terapia imunossupressora, do manejo e prevenção de infecções, da técnica cirúrgica e da indicação e seleção adequada dos pacientes é crucial para melhorar a sobrevida desse transplante.

Chimerism and tolerance in rat recipients of intestinal allografts from ALS-treated donors with and without adjunct naïve-donor-strain bone-marrow cells

BACKGROUND

BN --> LEW small-intestine transplantation (SITx) given a 28-day course of tacrolimus results in partial tolerance and prolonged alloengraftment despite the development of indolent chronic rejection (CR). We determined whether the CR was associated with the quantity or quality of passenger leukocytes contained in the unmodified or antilymphocyte serum (ALS)-depleted BN intestine at the time of transplantation, and with the subsequent migration and persistence of these donor leukocytes in the LEW recipients (chimerism).

METHODS

Four experimental cohorts were defined by differences of the BN allografts and by the infusion (or not) of naïve donor (bone marrow cells [BMC]) on the day of the BN --> LEW SITx. All LEW recipients were treated with the same 28-day course of tacrolimus. The LEW animals received: (1) unaltered intestine; (2) intestine from ALS-treated donor; (3) intestine from ALS-treated donor plus BMC from naive BN donor on day 0; and (4) unaltered intestine and BMC from unmodified (naïve) BN donor.

RESULTS

Blood chimerism during the first 2 weeks after transplantation was lowest in the recipients of intestine from ALS-treated donors (groups 2 and 3), apparently because of the nearly complete elimination from the bowel of alphabetaTCR+ passenger leukocytes. After 2 weeks posttransplant to 5 months, greater than 2% of circulating donor cells were seen in animals given adjunct BMC from naïve BN donors (groups 3 and 4); this was associated with the absence of CR in the intestinal allografts. With lower levels of chimerism, moderate CR including arteritis and fibrosis in the Peyer's patches and mesenteric lymph nodes was found in the intestinal grafts of all group 1 and group 2 animals. Nevertheless, the CR-prone recipients in groups 1 and 2 had equivalent weight gain for greater than or equal to 150 days as in the CR-free groups 3 and 4. Detailed tissue chimerism studies in groups 1 to 3 showed that most of the donor cells in the gut-associated lymphoid tissues were rapidly replaced, but that the residual donor constituency of up to 6% in the allografts of group 3 was nearly 10-fold greater at 150 days than in groups 1 and 2 and closely reflected the findings in blood.

CONCLUSION

The development of CR in intestinal allografts to which the recipients are partially tolerant is associated with a decline with time of donor-leukocyte chimerism. Multilineage chimerism in the recipient, and a similar profile of donor cells in the allografts, is better achieved with infused donor BMC than with the normal intestinal passenger leukocytes of the intestine. The difference may be because of a higher number of precursor and pluripotent stem cells in BMC.

Alemtuzumab (Campath-1H) combined with tacrolimus in intestinal and multivisceral transplantation

BACKGROUND

We combined alemtuzumab (Campath-1H, Berlex Laboratories, Montville, NJ) and tacrolimus (Tac) immunosuppression for intestinal and multivisceral transplantation.

MATERIALS AND METHODS

A total of 21 adult patients received 24 grafts: 14 intestinal, nine multivisceral, and one liver-intestinal graft. Alemtuzumab was administered perioperatively in four doses with low-dose Tac (levels 10-15 ng/dL) and no maintenance steroids. Tac was substituted with sirolimus in case of Tac-related complications. Suspected or mild rejections were treated with steroids. Moderate rejections were treated with steroids or OKT3. Severe rejections were treated with OKT3.

RESULTS

Of the 16 patients that were followed up for an average of 9 months, 12 are alive with functioning grafts. Two patients experienced severe rejection, three experienced moderate rejection episodes, and seven experienced mild acute rejection episodes. Four patients never developed acute rejection. Infectious complications included a cytomegalovirus enteritis and four fungal infections (related to central venous access).

CONCLUSIONS

The combination of alemtuzumab and Tac therapy without steroid use seems to efficiently prevent acute rejection in a significant number of patients without causing frequent opportunistic infections.

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.

Clinical intestinal transplantation: a decade of experience at a single center

OBJECTIVE

To assess the long-term efficacy of intestinal transplantation under tacrolimus-based immunosuppression and the therapeutic benefit of newly developed adjunct immunosuppressants and management strategies.

SUMMARY BACKGROUND DATA

With the advent of tacrolimus in 1990, transplantation of the intestine began to emerge as therapy for intestinal failure. However, a high risk of rejection, with the consequent need for acute and chronic high-dose immunosuppression, has inhibited its widespread application.

METHODS

During an 11-year period, divided into two segments by a 1-year moratorium in 1994, 155 patients received 165 intestinal allografts under immunosuppression based on tacrolimus and prednisone: 65 intestine alone, 75 liver and intestine, and 25 multivisceral. For the transplantations since the moratorium (n = 99), an adjunct immunosuppressant (cyclophosphamide or daclizumab) was used for 74 transplantations, adjunct donor bone marrow was given in 39, and the intestine of 11 allografts was irradiated with a single dose of 750 cGy.

RESULTS

The actuarial survival rate for the total population was 75% at 1 year, 54% at 5 years, and 42% at 10 years. Recipients of liver plus intestine had the best long-term prognosis and the lowest risk of graft loss from rejection (P =.001). Since 1994, survival rates have improved. Techniques for early detection of Epstein-Barr and cytomegaloviral infections, bone marrow augmentation, the adjunct use of the interleukin-2 antagonist daclizumab, and most recently allograft irradiation may have contributed to the better results.

CONCLUSION

The survival rates after intestinal transplantation have cumulatively improved during the past decade. With the management strategies currently under evaluation, intestinal transplant procedures have the potential to become the standard of care for patients with end-stage intestinal failure.

Irreversible intestinal failure, nutrition support, and small bowel transplantation

OBJECTIVES

Prolonged total parenteral nutrition (TPN) is a palliative but life-saving treatment for patients with irreversible intestinal failure (IIF). During the past few years, intestinal transplantation (ITx) has become the most realistic alternative to TPN.

METHODS

We identified potential candidates for ITx, reported clinical data of the international Intestinal Transplant Registry, and analyzed the intestinal function after transplantation and the common nutrition strategies usually adopted in the recipients.

RESULTS

At present, candidates for ITx are patients with IIF who develop a life-threatening complication during TPN treatment. During the past few years, clinical results have improved mainly in relation to the progress in immunosuppression, but prevention of the acute cellular rejection (ACR) is still the key point. ACR, high doses of immunosuppressant drugs, and intestinal bacterial translocation can exacerbate intestinal malabsorption and sustain systemic complications such as sepsis and multiorgan failure. Early enteral alimentation is started after ITx and gradually increased. To prevent dehydration and malnutrition caused by persistent diarrhea, parenteral nutrition is frequently maintained for 1 to 2 mo. More than 66% of long-term recipients become nutritionally independent of TPN.

CONCLUSIONS

ITx is now a life-saving option for patients with IIF and severe complications from TPN. Clinical and nutritional management of the recipients is a complex procedure and requires a great deal of expertise. After transplantation most adults maintain adequate nutrition status and children have normal growth. Multiple episodes of ACR, early and persistent dehydration, and malabsorption are still common problems that influence the recipient's quality of life.