摘要:

Today, the major problem in organ transplantation is not acute graft rejection but chronic graft deterioration. In addition to alloantigen-specific events, alloantigen independent factors like donor age, previous diseases, consequences of brain death, and perioperative events of ischemia/reperfusion injury have a major impact on long-term graft function. The induction of the stress protein heme oxygenase-1 (HO-1) protects cells from injury and apoptosis. Here, we tested the protective effects of HO-1 induction in a clinically relevant kidney transplant model.Induction of HO-1 expression following cobalt-protoporphyrin (CoPP) treatment in organ donors prolonged graft survival and long-term function remarkably following extended periods of ischemia. Positive effects were observed with both optimal and marginal grafts from old donor animals. Structural changes characteristic for chronic rejection, as well as graft infiltration by monocytes/macrophages and CD8+ T cells, were substantially reduced following HO-1 induction. Up-regulation of HO-1 expression before organ transplantation was also associated with reduced levels for tumor necrosis factor (TNF)-&agr; mRNA, increased levels for interferon (IFN)-&ggr;, and bcl-x, and insignificant differences for CD25, interleukin (IL)-2, IL-4, IL-6, and IL-10 mRNA levels. The significant improvement of long-term graft function following induction of HO-1 expression in donor organs suggests that this strategy may be a novel clinical treatment option with particular relevance for transplantation of marginal organs.

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.FTY720 is a novel immunomodulator that may provide an opportunity for a reduction in calcineurin inhibitor dosage in transplant recipients with renal/hepatic side effects. However, the effects of FTY720 on renal or hepatic hemodynamics are unknown. The aim of this study was to establish the hemodynamic and renal actions of FTY720 at therapeutically relevant dosages.Methods.The effects of acute and repeat oral administration of FTY720 on systemic, renal, and hepatic hemodynamics were investigated in the anesthetized male Lewis rat. Renal function and renal tubular parameters were examined in animals that received repeat high dosage of FTY720.Results.Seven-day oral administration of FTY720 did not cause any significant changes in markers of hepatocyte injury, nor did it cause any reduction in renal function (elevated urea and creatinine). Histological examination of liver and kidney from animals treated with repeat FTY720 for 1 or 3 weeks did not reveal any sclerosis, tubular changes, infiltrates, or fibrosis. Hepatocyte, vascular, and biliary structures were normal. Compared with the vehicle (saline), oral administration of FTY720 at dosages up to 5 mg/kg/day for 1 week did not have any significant effects on systemic, hepatic, or renal hemodynamics. Five min after intravenous FTY720 administration (1 mg/kg), mean arterial pressure (MAP) rose to 114±3.3% of baseline (P<0.01) before returning to the normal range within 30–45 min. Lower doses of FTY720 (0.3 and 0.5 mg/kg, i.v.) did not affect MAP. Renal cortical perfusion, renal artery blood flow, and renal vascular resistance were not altered by FTY720 at i.v. doses up to 1 mg/kg. Animals that received FTY720 (5 mg/kg/day) for 3 weeks showed a significant reduction in body weight (−4.8±1% of baseline at 3 weeks,P<0.001); however, weight-adjusted creatinine clearance, 24 h urine production, and urine osmolality were not different from those in control animals (0.71±0.1 vs. 0.74±0.1 ml/min/100 g, 2.63±0.2 vs. 3.12±0.2 ml/100 g, and 2003±33 vs. 1966±56 mOsm/kg, respectively). FTY720 at the same repeat oral dosage was, nevertheless, associated with a significantly lower 24 h sodium excretion and a significantly lower fractional excretion of sodium compared with those in control animals (223.4±35 vs. 304.5±50 &mgr;mol/100 g and 1.75±0.3 vs. 2.23±0.3%, respectively;P<0.05).Conclusions.Our data indicate that, at least in the short term, oral FTY720 does not cause any significant adverse effects on renal or hepatic hemodynamics, nor does it cause any reduction in glomerular perfusion and thus may provide reasonable rescue/add-on therapy in calcineurin-inhibitor treated transplant recipients. At high repeat oral dosages, however, FTY720 may alter renal handling of sodium.

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Successful islet transplantation in type 1 diabetes requires tolerance induction of both allo- and autoreactive T-cell responses. Monoclonal antibodies targeting the CD4 coreceptor on T-helper cells have been shown to be effective in this regard. In type 1 diabetes, there is some evidence to suggest that cytokines such as interleukin (IL)-1 may be involved in &bgr;-cell destruction. The high glucose levels associated with type 1 diabetes are also known to be toxic to beta cells.Method.The tempo of T-cell and macrophage infiltration into syngeneic islets transplanted into diabetic nonobese diabetic (NOD) mice was examined by immunohistochemistry. We investigated the ability of a nondepleting anti-CD4 monoclonal antibody (YTS177) to induce tolerance to syngeneic islet grafts in female spontaneous diabetic NOD mice and in an adoptive transfer model of diabetes in NOD mice. The spontaneous model was used to test the effect on graft function of perioperative insulin therapy in mice treated with YTS177. The ability of soluble interleukin (sIL)-1 receptor (R) type II (sIL-1RII) to inhibit IL-1 effects in syngeneic islet transplants was also assessed.Results.Cellular infiltration of CD3+cells and macrophages into the islet graft coincided with loss of graft function in untreated mice. Self-tolerance to beta cells was restored with YTS177, allowing long-term graft survival in a proportion of animals. The use of perioperative insulin therapy increased the number of successful grafts in spontaneously diabetic NOD mice treated with YTS177. The combination of YTS177 with sIL-1RII significantly improved the rates of graft survival compared with graft survival in YTS177-treated spontaneously diabetic NOD mice.Conclusions.Nondepleting anti-CD4 antibodies restore self tolerance to syngeneic islet transplants in diabetic NOD mice. Insulin therapy improves graft survival in mice treated with YTS177. Preventing the action of IL-1 greatly improves graft survival induced with YTS177.

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Using tissue-engineering techniques, we have developed aneointestinethat regenerates structural and transporter properties of native jejunum. The purpose of this study was to characterize the mucosal immune system of the engineered neointestine. We hypothesized that the neointestinal mucosa is capable of developing a mature immunocyte population and that exposure to luminal stimuli is critical to this development.Methods.Neointestinal cysts were engineered by implanting polymer-organoid constructs into syngeneic adult recipients. Neointestine (cysts left nonanastomosed [NA] and cysts anastomosed to native bowel [AN]) and native jejunum were harvested serially (3–56 weeks postoperatively). Immune cell subsets were characterized by the immunohistochemical detection of cell-specific antigens (T cells [CD3], B cells [CD32], NK cells [CD56], and macrophages [CD68]) combined with computer-based morphometry.Results.Intraepithelial and lamina propria immunocyte population densities and subset distributions were identical in AN cysts harvested 20 weeks postoperatively and in native jejunum. Mucosal immunocyte population densities were lower in AN cysts harvested 10 weeks postoperatively and only rudimentary in NA cysts, even those harvested 20 weeks postoperatively.Conclusions.These results suggest that tissue-engineered intestine has the capacity to develop a mucosal immune system with an immunocyte population similar to that of native small intestine. The development of this immune system is a function of both exposure to luminal stimuli and the duration of this exposure. Tissue-engineered intestine offers promise as a new therapeutic approach for patients who have intestinal insufficiency.

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Glycosaminoglycans (GAGs) are heteropolysaccharides present as integral components of the extracellular matrix (ECM), cell and basement membranes. GAGs play an important role in immune and inflammatory responses because of their ability to interact with cytokines and chemokines, promoting the localization of these molecules onto the ECM or cell membranes at specific anatomical sites. The main goal of these studies was to test the hypothesis that interference with the binding of cytokines/chemokines to GAGs will interfere with a graft rejection response.Methods.MC-2, a cationic peptide derived from the sequence of the heparin-binding domain of mouse interferon gamma, was used as an inhibitor of the binding of cytokines/chemokines to GAGs. The effects of this peptide were studied in an allogeneic transplantation model involving vascularized rat skin flaps.Results.The MC-2 peptide was found to inhibit binding of interferon-&ggr;, as well as that of the chemokines, interleukin-8, interferon gamma inducible protein-10, and regulated on activation normal T cell expressed and secreted (RANTES), to GAGs in vitro. Direct administration of MC-2 in an allogeneic skin flap transplantation model resulted in a significantly delayed time of rejection, from 5.4 ± 0.5 days (control; n=6) to 12.6 ± 1.6 days (treated animals; n=10). Histopathologic analysis of the skin biopsies was consistent with the delayed rejection process in those animals receiving the peptide, showing only mild signs of rejection up to day 11 (in contrast, all control animals had rejected their flaps by day 6).Conclusions.These results are consistent with the idea that GAG-cytokine interactions constitute valid therapeutic targets and suggest the potential applicability of such an approach in the prevention of graft rejection.

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.The tolerogenic activity of allogeneic bone marrow cells (BMCs) associates with functional inactivation of alloreactive T cells and has been attributed to a veto effect. Studies in mice and rhesus monkeys indicated that the CD8&agr; molecule expressed on a subpopulation of allogeneic BMCs is necessary to induce signal transduction within the BMCs to increase veto effector molecules such as transforming growth factor (TGF)-&bgr;1. In vitro activation of alloreactive cytotoxic T-lymphocyte precursor enhances their susceptibility to veto-mediated functional inactivation by specific alloantigen-bearing BMCs. Accordingly, we examined a hypothesis that mature rhesus monkey (Rh) monocyte-derived dendritic cells (MDDCs) modified by gene transfer to over-express active TGF-&bgr;1 might mediate veto activity without the need to express CD8&agr;.Methods.Rh MDDCs were modified by recombinant adenovirus (Ad) transduction and characterized by phenotype and functional studies.Results.Rh MDDC transduction with Ad vectors using conventional methods was remarkably inefficient. However, a single-chain anti-CD40/soluble Coxsackie and adenovirus receptor-fusion protein (G28/sCAR) permitted high-efficiency transduction of Rh MDDCs by retargeting Ad to Rh MDDC CD40. Mature Rh MDDCs that were transduced to overexpress active TGF-&bgr;1 (AdTGF-&bgr;1 Rh MDDC) significantly suppressed alloimmune responses in [3H]thymidine uptake mixed leukocyte reaction assays. We showed by the carboxyfluorescein succinimidyl ester dilution method that allogeneic mature AdTGF-&bgr;1 Rh MDDCs inhibited proliferation of CD4+and CD8+responder T cells. Notably, AdTGF-&bgr;1 Rh MDDC abrogated alloimmune responses induced by control AdGFP Rh MDDC in an antigen-specific manner.Conclusions.These results suggest that nonhuman primate mature MDDCs can be genetically engineered to function as alloantigen-specific cellular immunosuppressants, an approach that has potential to facilitate induction of allograft tolerance in vivo.

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Elimination of galactose-&agr;1,3-galactose (Gal), the major xenoantigen between pig and human, may extend pig-to-human xenograft survival beyond the current barrier of acute vascular rejection. However, it has been suggested that Gal is an essential molecule in the pig and that the generation of a Gal-deleted (Gal KO) pig will not be possible. Should this be the case, understanding the Gal-mediated immune response will be crucial in developing strategies to overcome pig xenograft rejection in humans. There are no existing models of xenograft rejection in which the sole difference between donor and recipient is Gal. We describe a model of exclusively Gal-mismatched skin graft rejection.Methods.The survival of Gal+/+skin grafts on Gal KO mice with the same genetic background was analyzed. To examine innate anti-Gal immunity, Gal KO recipients that were also deficient in T and B cells (RAG-1 KO) were used. To study the role of cognate immunity, recipients were sensitized with a primary Gal+/+allograft before receiving a second Gal+/+graft that was otherwise isogeneic. To test the role of anti-Gal antibodies in this model, recipients were passively immunized with a non–complement-fixing anti-Gal monoclonal antibody.Results.Gal KO mice chronically reject Gal+/+skin grafts by 100 days at a rate of 48% (n=25) on a BALB/c background and 25% (n=8) on a C57BL/6 background. The grafts had an infiltrate that consisted predominantly of CD4+T cells and macrophages, whereas recipients deficient in T and B cells were incapable of rejection and survived for more than 120 days (n=5). Sensitization with a primary Gal+/+allograft increased the incidence and the tempo of rejection of a second Gal-only mismatched skin graft with 99% rejection that ranged from 11 to 45 days (n=26). Passive transfer of mouse IgG1anti-Gal monoclonal–antibody-induced rejection in Gal KO and RAG-1/Gal double-KO recipients at a rate of 92% (n=13).Conclusions.We have established a model to study rejection based solely on a Gal mismatch. Our results indicate that non–complement-fixing anti-Gal antibody can cause rejection in the acute vascular rejection time frame and that T-cell–mediated chronic rejection will be a further barrier to overcome if Gal cannot be deleted from the pig.

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Both T and B cells have been shown to be implicated in the pathogenesis of bronchiolitis obliterans syndrome, which is considered to represent chronic lung allograft rejection. However, the relative contributions of T cells and alloantibodies in the pathogenesis of the disease are still unknown. In this study, we used an heterotopic murine tracheal transplantation model to determine the contribution of these components of the immune system in the pathogenesis of posttransplant obliterative airway disease (OAD).Methods.Tracheal allografts from BALB/c and HLA-A2-transgenic (HLA-A2+) mice were heterotopically transplanted into C57BL/6, CD4-knockout (KO), CD8-KO, Ig-KO, and Rag1-KO mice. In additional experiments, recipient mice were pretreated with depleting antibodies against CD4+, CD8+, and NK1.1+ cells. Development of OAD was determined by histopathology at days 10, 30, 60, 90, and 180 after transplantation.Results.HLA-A2+ allografts transplanted into C57BL/6, CD8-KO, and Ig-KO mice demonstrated OAD lesions by day 30. In contrast, allografts transplanted into CD4-KO mice showed no OAD lesions at day 30, partial OAD development by days 60 and 90, and complete OAD development by day 180. No OAD development was observed in allografts transplanted into Rag1-KO mice. Treatment with anti-NK1.1 antibody did not show any effect on posttransplant OAD development. In contrast, anti-CD4+ or anti-CD8+ antibody treatments partially reduced the OAD histopathology and combined anti-CD4/CD8 antibody treatment further abrogated the histopathology of the disease.Conclusion.These results show that both CD4+ and CD8+ T cells have a role in the pathogenesis of OAD and that natural killer cells and alloantibodies are not necessary for the development of this disease.

ISSN:0041-1337    

出版商:OVID    

年代:2002

数据来源: OVID