Small Bowel Allograft Research Articles

Intestinal crypt cell apoptosis during small bowel allograft rejection is independent upon donor-derived inducible nitric oxide synthase (iNOS)

Intestinal crypt cell apoptosis during small bowel allograft rejection is independent upon donor-derived inducible nitric oxide synthase (iNOS)

CXCR3, but not CCR5, +ve host T cells are predominant in lamina propria infiltrates in early acute small bowel allograft rejection

CXCR3, but not CCR5, +ve host T cells are predominant in lamina propria infiltrates in early acute small bowel allograft rejection

Graft mucosal blood flow is reduced prior to histologic evidence of rejection in mouse small bowel transplantation: a murine model

THE SUCCESS of small bowel transplantation is hampered by vigorous and early acute rejection responses. At present, the diagnosis of acute rejection is based mainly on histology and endoscopy. The late onset of morphologic changes and the initial patchy pattern makes it hard to discover early. Therefore efforts continue to identify novel and effective means for early diagnosis of acute rejection in intestinal transplantation. It has been demonstrated that one of the first targets in acute rejection of the small bowel allograft is the vascular endothelial cells in the lamina propria. This response may result in early mucosal microcirculatory disturbances and progressive ischemia that eventual lead to morphologic changes. We assumed that this attack on the microvasculature would be reflected in mucosal blood perfusion. Mucosal perfusion was measured by means of laser Doppler flowmetry at different time intervals and compared with synchronous histologic samples.

Small bowel allografts maintained by administration of Bombesin while under immunosuppression

Background/Purpose: The aim of this study was to determine if Bombesin (BBS) could help maintain the mucosal villus state in small bowel allografts without inducing acute rejection under immunosuppression. Methods: Allogeneic small bowel transplantation was performed heterotopically in rats (n = 12). All rats received daily administration of FK506 from postoperative day 0 to day 28. On postoperative day 14, rats were divided into 2 groups of 6 rats each, and administered BBS or normal saline as a control. After 2 weeks of treatment, the rats were killed, and the graft mucosal villus state was evaluated by H&E staining, and crypt cell proliferation analysis was performed using immunohistochemistry with proliferative cell nuclear antigen (PCNA). Results: Villi were thin, and villus blunting was marked in the control group. The BBS group showed that the villi of the grafts were well maintained, and the volume of the lamina propria mucosa was adequately preserved. The PCNA labeling index of crypt cells in the control group was 40.06 ± 3.36 (mean ± SD) and that in the BBS group was 61.02 ± 4.27. There was a significant difference (P <.001) between the 2 groups. Conclusions: BBS maintained allograft epithelial cells and the volume of the lamina propria intestinal mucosa, stimulating proliferation of crypt cells under immunosuppression without inducing acute rejection. J Pediatr Surg 38:83-87. Copyright 2003, Elsevier Science (USA). All rights reserved.

Chimerism induction by nonmyeloablactive preconditioning and bone marrow infusion in rat small bowel transplantation

In our previous work we demonstrated that the use of donor specific bone marrow infusions ( DSBMI ) after small bowel transplantation did not improve the graft survival after a short course of immunossupression. PURPOSE: In the current study, we evaluated whether recipient preconditioning with different regimens of radiation combined with DSBMI may enhance small bowel allograft survival with minimum recipient morbidity. METHODS: Heterotopic small bowel transplantation (SBTx) was performed with Lewis rats as recipients and DA rats as donors, which were immunossupressed with a short course of tacrolimus (FK 506 ) at 1mg/Kg/day for 5 days and distributed in 4 groups: group 1 (n= 4) without both irradiation and DSBMI; Groups 2 (n= 6), 3 (n= 9) and 4 (n= 6) received 100 x 10(6) DSBM cells at the time of the transplant. Groups 3 and 4 were irradiated with 250 and 400 rd respectively. Animals were examined daily for clinical signs of rejection or GVHD. Blood samples were taken weekly for chimeric studies by FC and intestinal biopsies were performed every 2 weeks. RESULTS: Animals in G1 and G2 had minimal rejection at day 15 after SBTx while GVHD was clinically and histologically characterized in G 3 and G 4. Total chimerism and T-cell chimerism was higher in irradiated groups when compared to non-irradiated groups. With exception of G1 and 2 where rejection was the cause of death, all animals in G3 and 4 died of GVHD. CONCLUSION:We concluded that low cytoreductive of irradiation can successfully decrease the graft rejection but not prevent the occurrence of GVHD.

Expression of Mucosal Addressin Cell Adhesion Molecule-1 (MAdCAM-1) During Small-Bowel Graft Rejection in Rats

Background: Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) is a critical endothelial adhesion molecule for lymphocyte trafficking to gut-associated lymphoid tissues (GALT) under physiological conditions. It is expressed on special postcapillary venules, that is the high endothelial venules (HEV) in GALT. In this study, we investigated changes in MAdCAM-1 expression during small-bowel graft rejection. Methods: Orthotopic small-bowel transplantation (SBT) with portacaval drainage was performed from brown Norway (BN) rats to Lewis (LEW) rats. Isografted (LEW → LEW) and untransplanted animals served as controls. Animals were killed on days 3, 4, 5, 6 and 7 after SBT. Cryostat sections (6 μm thick) were prepared from normal small-bowel tissues and small-bowel grafts, including Peyer patches (PPs). Indirect immunoperoxidase staining was performed using monoclonal antibodies (mAbs) against rat MAdCAM-1 (OST12). Results: In the PPs of controls, MAdCAM-1 antibodies specifically stained the endothelial cells of HEV, which were predominantly located in the interfollicular areas. In the allografts on day 4 after SBT, the MAdCAM-1 expression was weaker on the HEV in the PPs than in the controls. In the lamina propria of controls, a faint expression of MAdCAM-1 on vessels was observed. On day 4 after allogeneic SBT, the MAdCAM-1 was more strongly expressed on the endothelial cells of the vessels at the base of the villi. As rejection developed, the MAdCAM-1 expression on the vessels progressed toward the villus tip. Conclusions: The change of MAdCAM-1 expression may be involved in the development of small-bowel graft rejection. The vessels at the base of villi, which is associated with lymphocyte recruitment, may become a site of intense immune reactivity in the early phase of small-bowel allograft rejection.

Diffuse mesenterial sclerosis: a characteristic feature of chronic small-bowel allograft rejection.

Chronic rejection is the major cause of late intestinal allograft dysfunction. The aim of this study was to analyze in detail the histopathological features of chronic rejection in the ACI-to-Lewis rat model of intestinal transplantation. Chronic rejection was achieved in orthotopic small-bowel allografts (ACI-Lewis) by limited immunosuppression with cyclosporin A (CyA). Isogeneic transplants (ACI-ACI) as well as native bowels (ACI) with and without immunosuppression served as controls. Bowels were removed together with the mesenteries 90 days postoperatively and analyzed using sections stained with hematoxylin and eosin as well as Masson's trichrome. The slides were coded, randomized and analyzed by grading of histological abnormalities. The most striking alterations of the allografts were noticed in the mesenteries exhibiting an extensive infiltration by mononuclear cells accompanied by a progressive diffuse fibrosis with shrinking of the mesenteries. These changes were most pronounced in the perivascular areas of the mesenteric arteriae and venae rectae. Three of five allografts showed vasculitis with myointimal proliferation of the arteriae rectae. Focally, there was spill-over of the inflammatory cells onto the intestinal muscularis propria. The mucosa of the allografts showed mild blunting, lymphocytic infiltration of the crypt epithelium and increased crypt cell apoptoses. The submucosa was unaffected, and there were no detectable abnormalities of the enteric ganglion cells. The present data support the view that chronic rejection of intestinal allografts is characterized by a diffuse sclerosing mesenteritis which may significantly contribute to late graft dysfunction. The present model may be useful to study the pathomechanisms of this inflammatory fibrosing process.

Prolongation of small bowel allograft survival with a sequential therapy consisting of a synthetic MHC class II peptide and temporarily low-dose cyclosporine A

It has been extensively documented the role of the indirect pathway of allorecognition in allograft rejection. However, recent data demonstrate that the manipulation of this pathway could be also sufficient to promote prolongation of allograft survival. In the present study we evaluated the effect of preoperative immunization with the WF-specific MHC class II peptides RT1.D2 and RT1.B2 in combination with low-dose CsA from days 0 to 7 (5 mg/kg/day) and from days 8 to 30 (1 mg/kg/day) after WF small bowel transplantation. Seven days before and on the day of transplantation, LEW recipients were immunized with the two WF MHC class II peptides RT1.B2 and RT1.D2. The CsA monotherapy induced an allograft survival of 49.3 ± 6.1 days. MHC class II peptide immunization had a limited effect on allograft survival for RT1.D2 (47.1 ± 3.8 days) and induced prolongation of allograft survival for RT1.B2 (73.6 ± 34.6 days). This effect seems to be based on the absence or silence of RT1.B2-reactive T cells and rejection seems to be correlated with the presence of RT1.B2-specific T cells in the late phase. Therefore, the combination of RT1.B2 with low-dose CsA shifts the immunological response and protects small bowel allograft rejection.

Association of the CD134/CD134L costimulatory pathway with acute rejection of small bowel allograft.

The CD134/CD134L interaction provides a strong costimulatory signal that is CD28-independent. The CD134/CD134L pathway has been studied in inflammatory, autoimmune diseases, and graft-versus-host disease, but no information exists on the involvement of CD134/CD134L interactions in solid organ transplantation. CD134/CD134L costimulation was studied in a rat model of small bowel transplantation. Immunohistochemistry and flow cytometry were used to analyze the expression and localization of CD134/CD134L. Mixed lymphocyte culture and quantitative RT-PCR were used to measure the effect on T proliferation and T helper cell cytokine transcripts of single or combined CD134 and CD28 costimulatory blockade. CD134 and CD134L molecules were strongly expressed in acutely rejected small bowel allografts. This expression was significantly suppressed by FK506. Interruption of the CD134 and CD28 costimulatory pathways resulted in an pronounced increase in expression of interleukin-10 transcripts. These results present the first evidence that the CD134/CD134L interaction is associated with acute allograft rejection. Combined CD134/CD134L blockade may be an effective treatment to both prevent acute allograft rejection and promote the induction of cells with regulatory capacity.

Mucosal vascular alterations in the early posttransplant period of small bowel allograft recipients may reflect humoral-based allograft rejection

Mucosal vascular alterations in the early posttransplant period of small bowel allograft recipients may reflect humoral-based allograft rejection

Immunohistochemical changes in matrix metalloproteinase-2 and 9 during small bowel allograft rejection in rats

Immunohistochemical changes in matrix metalloproteinase-2 and 9 during small bowel allograft rejection in rats

A clinicopathologic study of isolated intestinal allografts with preformed IgG lymphocytotoxic antibodies

m Humoral rejection of human small bowel allografts has not been ell documented. The aim of this study was to determine the signifcance of preformed IgG lymphocytotoxic antibodies, as determined y the modified Amos crossmatch technique, in 6 of 28 (21.4%) adult solated intestinal allograft recipients treated with tacrolimus basal mmunosuppression. The crossmatch with dithiothreitol (DTT) was trongly positive in 5 grafts and weakly positive in the remaining one. he strongly positive crossmatch grafts (n 5) developed severe ucosal injuries immediately after reperfusion. Within the first 10 ays after transplantation, 3 of the 5 strongly positive crossmatch rafts developed clinically and endoscopically documented severe ucosal congestion, cyanotic discoloration, and focal hemorrhage ithin the allograft. Simultaneous mucosal biopsy specimens demontrated severe congestion, neutrophilic margination, and fibrin-plateet thrombi within the lamina propria microvasculature, along with ocal hemorrhage, but with no histological neutrophilic or necrotizng arteritis, and the immunofluorescent findings were unremarkable. he other 2 strongly positive crossmatch allograft recipients develped macroscopic congestion of mucosa with microscopic foci of ongestion and hemorrhage. In contrast, the recipient with a weakly

Concomitant liver transplantation reduces the rate of chronic small bowel allograft rejection

Concomitant liver transplantation reduces the rate of chronic small bowel allograft rejection

Oral beclomethasone therapy for recurrent small bowel allograft rejection and intestinal graft-versus-host disease

INTESTINAL transplantation is an accepted therapy for short bowel syndrome in individuals with life-threatening complications of total parenteral nutrition (TPN). The primary problem preventing wider application of small bowel transplantation electively is the high levels of immunosuppression required to prevent rejection of the small bowel graft and the 20% incidence of graft loss due to rejection despite these high levels. Oral beclomethasone has been used experimentally in the treatment of inflammatory bowel disease and intestinal graft-versus-host disease (GVHD) associated with bone marrow transplantation. It acts primarily as a topical steroid without high levels of systemic absorption that would lead to adrenal suppression. There are currently no reports in the literature describing the use of beclomethasone in small bowel transplant recipients. The striking similarity between GVHD and acute small bowel allograft rejection histologically suggests beclomethasone may have a role in treating and preventing recurrent acute rejection. Herein we present the results of oral beclomethasone treatment in three small bowel transplant recipients who had multiple episodes of acute small bowel rejection and one with GVHD.

Donor T cell activation initiates small bowel allograft rejection through an IFN-gamma-inducible protein-10-dependent mechanism.

The poor success in controlling small bowel (SB) allograft rejection is partially attributed to the unique immune environment in the donor intestine. We hypothesized that Ag-induced activation of donor-derived T cells contributes to the initiation of SB allograft rejection. To address the role of donor T cell activation in SB transplantation, SB grafts from DO11.10 TCR transgenic mice (BALB/c, H-2L(d+)) were transplanted into BALB/c (isografts), or single class I MHC-mismatched (L(d)-deficient) BALB/c H-2(dm2) (dm2, H-2L(d-)) mutant mice (allografts). Graft survival was followed after injection of control or antigenic OVA(323-339) peptide. Eighty percent of SB allografts developed severe rejection in mice treated with antigenic peptide, whereas <20% of allografts were rejected in mice treated with control peptide (p < 0.05). Isografts survived >30 days regardless of OVA(323-339) administration. Activation of donor T cells increased intragraft expression of proinflammatory cytokine (IFN-gamma) and CXC chemokine IFN-gamma-inducible protein-10 mRNA and enhanced activation and accumulation of host NK and T cells in SB allografts. Treatment of mice with neutralizing anti-IFN-gamma-inducible protein-10 mAb increased SB allograft survival in Ag-treated mice (67%; p < 0.05) and reduced accumulation of host T cells and NK cells in the lamina propria but not mesenteric lymph nodes. These results suggest that activation of donor T cells after SB allotransplantation induces production of a Th1-like profile of cytokines and CXC chemokines that enhance infiltration of host T cells and NK cells in SB allografts. Blocking this pathway may be of therapeutic value in controlling SB allograft rejection.

Apoptosis and CD8 and CD54 Cell Expression in Rat Small Bowel Transplantation

The importance of activated CD8 cells expressing IL-2R in small bowel and other organ rejection has been reported. Some authors even consider that a positive correlation might be demonstrated between the number of apoptotic enterocytes and the degree of graft rejection. In addition, moderate to intense activation of endothelial molecules in small bowel allograft in rats has been reported in chronic rejection. The aim of the present paper is to ascertain, in a heterotopic small bowel transplantation (HSBT) in rats, whether CD3, CD4, CD8, and CD54 cell expression in the allograft infiltrates shows some relationship with allograft enterocyte apoptosis when rejection is present. Wistar Furth male rats were allotted to two groups: group A was the control group without transplantation; group B received a heterotopic small bowel allograft from Fisher rats and an im dose of FK506 (0.25 mg/kg/day). A significant increase of CD8, CD54 cell receptor expression, and apoptosis in the group undergoing HSBT showed rejection. No significant differences have been observed in the variables under study between the control and HSBT without rejection groups or in CD3 and CD4 among the three groups. We observed a significant correlation between apoptosis and rejection, between CD8 and CD54 with apoptosis and with rejection, and between CD8 and CD54. This indicates that the activation of endothelial molecules and cells may play an important role in established HSBT chronic rejection. We consider that this study may contribute to the knowledge of small bowel allograft chronic rejection and its immunomodulation.

Elimination of donor-specific alloreactivity prevents cytomegalovirus-accelerated chronic rejection in rat small bowel and heart transplants.

The primary cause for late failure of vascularized allografts is chronic rejection (CR) characterized by transplant vascular sclerosis (TVS). Cytomegalovirus (CMV) infection accelerates TVS and CR by unclear mechanisms involving direct effects of CMV, indirect effects of the recipient's immune response to CMV, or interactions between CMV and the recipient's alloreactivity. This study examined the role of CMV and the alloreactive response in the development of TVS using bone marrow chimerism (BMC) in rat small bowel (SB) and heart transplantation models. Fisher 344 (F344) rat heart or SB grafts were transplanted into F344/Lewis bone marrow chimera. F344 heart or SB grafts transplanted into Lewis recipients (low-dose cyclosporine) were positive controls for the development of TVS. Lewis heart or SB grafts transplanted into Lewis recipients (+/-cyclosporine) were transplantation controls. The effect of rat CMV (RCMV) (5x105 plaque-forming units) on TVS (neointimal index, NI) and graft survival was studied in these groups. RCMV infection was assessed by serologic analysis and quantitative polymerase chain reaction techniques (TaqMan). RCMV infection accelerated the time to graft CR (SB 70-38 days; hearts 90-45 days) and increased the severity of TVS in both the SB allografts (day 38, NI=27 vs. 52) and the heart allografts (day 45, NI=43 vs. 83). Grafts from CMV-infected syngeneic recipients failed to develop TVS and CR. Donor-specific tolerance induced by BMC prevented allograft TVS and CR in both transplant models. In contrast to naïve Lewis recipients, RMCV infection failed to cause allograft TVS and CR in bone marrow (BM) chimeras. The events in CMV-induced acceleration of TVS involve a crucial interplay between CMV infection and the recipient's alloreactive immune response.

Early diagnosis of small bowel allografts rejection by Doppler ultrasound fluxometry

Early diagnosis of small bowel allografts rejection by Doppler ultrasound fluxometry

Origin and immunophenotype of intestinal intraepithelial lymphocytes in experimental long-surviving small bowel allografts

Origin and immunophenotype of intestinal intraepithelial lymphocytes in experimental long-surviving small bowel allografts

Myoelectric activity during chronic small bowel allograft rejection in rats.

The aim of this study was to analyze the effect of chronic rejection on myoelectric activity of orthotopic small intestine transplants in vivo. Chronic rejection was achieved in orthotopic small bowel allografts (ACI-Lewis) using cyclosporin A for limited immunosuppression. Isogeneic transplants (ACI-ACI) as well as native bowels (ACI) with and without immunosuppression served as controls. Myoelectric activities were recorded after a 12-hr fasting period and analyzed visually. Pacemaker frequencies within grafts were significantly below normal values (group 1: 37; group 2: 31.7; group 3: 37; group 4: 32.3). MMC periods and MMC phases did not show significant differences. The propagation velocity of phase III contractions was elevated in the ileum of grafts undergoing chronic rejection (group 1: 1.79; group 2: 1.59; group 3: 2; group 4: 2.5). In conclusion, fasting motility is altered but preserved in intestinal allografts undergoing chronic rejection. Intrinsic reinnervation from the native duodenum, which is necessary to generate normal pacemaker frequencies, was observed neither in allografts nor in isografts after a three-month period.