ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background.Because epithelial cells are targets of alloimmune injury leading ultimately to airway obliteration, we tested whether epithelial re-growth could prevent obliterative airway disease (OAD) in orthotopic tracheal allografts.Methods.Brown Norway tracheal segments were orthotopically transplanted into nonimmunosuppressed Lewis rats. Allografts were removed on days 2–10 (n=13), 30 (n=4), and 60 (n=5) for histology, computerized morphometry (obliteration), and immunohistochemical detection of mononuclear cells, smooth muscle &agr;-actin, and tissue phenotype. Normal tracheas, host tracheas, and heterotopically transplanted allografts served as controls.Results.Orthotopic allografts removed on days 2–10 exhibited epithelial damage and re-growth and mononuclear cell infiltration. On days 30 and 60, partially ciliated cuboidal or attenuated epithelium completely covered the lumen. Although mononuclear cells declined, numerous T cells with a high CD4/CD8 ratio were found in the epithelium till day 60. Orthotopic allograft epithelium expressed donor phenotype on day 7, but recipient phenotype on days 30 and 60. Despite subepithelial &agr;-actin positive myofibroblast proliferation, obliteration did not progress from day 7 to 30 and 60 (35, 30, and 33%, respectively). Although more than in normal or host tracheas, the obliteration in orthotopic allografts on days 30 and 60 was significantly less (P<0.001) than in heterotopic allografts.Conclusions.We describe, for the first time, long-term patency of fully histoincompatible orthotopic tracheal allografts in nonimmunosuppressed rats. Despite acute alloimmune injury and induction of myofibroblast proliferation, epithelial re-growth from the host limited the progression of OAD, thus emphasizing the role of epithelium in the control of airway obliteration.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background.ExtracellularATP and ADP may be important mediators of vascular inflammation and thrombosis. Nucleoside triphosphate diphosphohydrolase (NTPDase or CD39) is a vascular ectoenzyme that hydrolyses ATP and ADP; however, this activity is lost during reperfusion injury. We show that the supplementation of NTPDase activity within xenograft vasculature using CD39 recombinant adenoviruses (AdCD39) has protective effects in vivo.Methods.Recombinant adenoviruses containing human CD39 or &bgr;-galactosidase (Ad&bgr;-gal) encoding genes were constructed. Hartley guinea pig coronary arteries were perfused ex vivo with University of Wisconsin solution containing 109plaque-forming units of the recombinant adenovirus. Infected grafts were then implanted in the abdomen of complement depleted Lewis rats.Results.NTPDase activities decreased in all grafts within the first 24 hr and subsequently recovered only in those hearts infected with AdCD39. Immunohistological examination of AdCD39-infected grafts confirmed successful CD39 gene transfer into the endocardium and macrovasculature. Expression of CD39 modestly prolonged graft survival (90.2±5.4 hr, mean±SD, n=5) when compared with Ad&bgr;-gal-infected grafts (67.4±5.4 hr,P<0.005) and perfusion controls (66.4±5.2 hr;P<0.005).Conclusions.Recombinant adenoviral infection can induce expression of CD39 within cardiac xenografts and provide survival benefits in vivo. Our data show that ex vivo infection by recombinant adenovirus vectors can result in vascular expression of a potential therapeutic agent.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background.We have previously shown successful engraftment of allogeneic hematopoietic stem cells (HSCs) when transplanted across the major histocompatibility antigen barriers if transplanted along with a preparation of facilitator cells (osteoblasts).We have investigated whether or not fully allogeneic HSCs from healthy mouse donors prevent the development of autoimmunities in the autoimmune-prone W/B F1 mice.Methods.W/B F1 is a strain of mice that spontaneously develop autoimmunities, a coronary vascular disease, thrombocytopenia, and systemic lupus-like syndrome. The 6- to 8-week-old (before the onset of the disease) W/B F1 mice have been transplanted with either a preparation of HSCs alone, or along with facilitator cells from MHC-incompatible autoimmune-resistant BALB/c mice, then followed to determine long-term survival and whether or not they developed signs of the autoimmune disease.Results.The number of the transplanted HSCs acts as the determining factor in achieving successful and durable engraftment. Survival of the W/B F1 mice significantly improved by transplantation of increasing numbers of HSCs, either alone or along with facilitator cells. When W/B F1 mice were transplanted with 2–5 million HSCs, more than 1-year survival was 100%, all the transplanted mice were fully engrafted with allogeneic HSCs, and were free of signs of the autoimmune disease. Histological sections of the hearts, lungs, and kidneys of the transplanted mice showed absence of the autoimmune-associated pathology.Conclusions.We thus report herein the successful prevention of autoimmune disease by transplantation of a sufficiently large number of purified fully allogeneic HSCs in W/B F1 mice.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background.In our previously described primate renal allograft model, T cell ablation leads to long-term graft survival.The role of endothelial cell alteration in chronic rejection was examined in our model.Methods.Renal transplants were performed in rhesus monkeys using a T cell- depleting immunotoxin, FN18-CRM9. Sections from 10 rejected kidneys (5 acute and 7 chronic rejection) were examined after immunohistochemical staining for expression of endothelium-related proteins [von Willebrand factor (vWF), CD62P, and CD31], fibrinogen, and a macrophage marker (CD68). Glomerular staining for each antigen was graded on a semiquantitative scale.Results.Intense staining for vWF was consistently observed in glomerular endothelium, subendothelium, and mesangium in all kidneys removed due to chronic rejection. vWF staining was weak in kidneys showing acute rejection. The difference in glomerular staining was statistically significant. Staining for vWF in extraglomerular vessels was nearly identical in kidneys showing acute and chronic rejection. Expression of CD62P was increased in extraglomerular vessels in allografts with chronic rejection, but the glomeruli showed little or no staining. There was no significant difference in the glomerular staining for CD62P or CD31 in organs showing acute and chronic rejection. Fibrinogen staining of glomerular mesangium was seen in kidneys with chronic rejection. Macrophages (CD68+) infiltrating glomeruli were more numerous in kidneys showing chronic rejection.Conclusion.Increased glomerular deposition of vWF in renal allografts showing chronic rejection, without increased staining for CD62P or CD31, suggests increased constitutive secretion of vWF from endothelial cells as a component of the mechanism of chronic rejection in our model.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background.Hyperacute rejection (HAR) and acute humoral rejection (AHR) remain recalcitrant conditions without effective treatments, and usually result in graft loss.Plasmapheresis (PP) has been shown to remove HLA- specific antibody (Ab) in many different clinical settings. Intravenous gamma globulin (IVIG) has been used to suppress alloantibody and modulate immune responses. Our hypothesis was that a combination of PP and IVIG could effectively and durably remove donor-specific, anti-HLA antibody (Ab), rescuing patients with established AHR and preemptively desensitizing recipients who had positive cross-matches with a potential live donor.Methods.The study patients consisted of seven live donor kidney transplant recipients who experienced AHR and had donor-specific Ab (DSA) for one or more mismatched donor HLA antigens. The patients segregated into two groups: three patients were treated for established AHR (rescue group) and four cross-match-positive patients received therapy before transplantation (preemptive group).Results.Using PP/IVIG we have successfully reversed established AHR in three patients. Four patients who were cross-match-positive (3 by flow cytometry and 1 by cytotoxic assay) and had DSA before treatment underwent successful renal transplantation utilizing their live donor. The overall mean creatinine for both treatment groups is 1.4±0.8 with a mean follow up of 58±40 weeks (range 17–116 weeks).Conclusions.In this study, we present seven patients for whom the combined therapies of PP/IVIG were successful in reversing AHR mediated by Ab specific for donor HLA antigens. Furthermore, this protocol shows promise for eliminating DSA preemptively among patients with low-titer positive antihuman globulin-enhanced, complement-dependent cytotoxicity (AHG-CDC) cross-matches, allowing the successful transplantation of these patients using a live donor without any cases of HAR.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background.In this study, the capacity of CD8+ T cells to act as a potential effector mechanism in pancreatic xenograft rejection was examined.Methods.The fate of pancreatic islet xenografts was studied in mice deficient in MHC class II molecules and CD4+ T cells. Fetal pig pancreas (FPP) or Wistar rat islets (RI) were transplanted into nondiabetic or streptozotocin-induced diabetic I-A knock-out (CII K/O) mice.Results.CII K/O mice were capable of rejecting both RI and FPP grafts. RI graft survival was not prolonged compared with wild type C57BL/6 controls. However, FPP grafts did survive longer in CII K/O recipients than in C57BL/6 mice. Both RI and FPP graft rejection were CD8+ T-cell phenomena in CII K/O mice, as anti-CD8 monoclonal antibody prolonged graft survival, there were increased CD8+ T cells in the grafts and spleens of CII K/O recipients, and cell-mediated cytotoxicity was a CD8+ T-cell phenomenon associated with activation of the perforin/granzyme B system. By contrast, RI and FPP graft rejection was a CD4+ T cell-dependent phenomenon in wild type C57BL/6 mice with graft survival prolonged by anti-CD4 monoclonal antibody. There were increased numbers of CD4+ T cells, and cell-mediated cytotoxicity was a CD4+ T-cell phenomenon associated with activation of the Fas/FasL lytic pathway.Conclusions.The results demonstrate that, in the absence of CD4+ T cells, CD8+ T cells were capable of rejecting both rat and pig pancreatic islet xenografts.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

We elucidated the possible role of chimerism in skin and heart allograft tolerance using cyclophosphamide (CP)-induced tolerance.When C3H (H-2k; Thy1.2, Mls-1b) mice were i.v. primed with 1×108spleen cells (SC) from H-2 matched AKR (H-2k; Thy1.1, Mls-1a) mice and then treated i.p. with 200 mg/kg of CP, the survivals of both AKR skin grafts and heart grafts (HG) were permanently prolonged in a tolerogen-specific fashion. After this treatment, a minimal degree of mixed chimerism, the clonal destruction of Mls-1a-reactive CD4+V&bgr;6+T cells in the periphery, and the clonal deletion of V&bgr;6+thymocytes were all observed. When AKR SC and 100 mg/kg CP were used for conditioning, the AKR HG were permanently accepted, but the survival of the AKR skin grafts was only mildly prolonged. The clonal destruction of CD4+V&bgr;6+T cells in the periphery and the intrathymic clonal deletion of V&bgr;6+thymocytes were induced in both the SC and the 100 mg/kg CP-treated C3H mice. A minimal degree of mixed chimerism was detectable at 4 and 12 weeks after AKR SC and 100 mg/kg CP treatment, and still did not disappear at 40 weeks. The degree of mixed chimerism induced with SC and 100 mg/kg CP was significantly lower than that with SC and 200 mg/kg CP during the observation. No posttransplant cardiac allograft vasculopathy (CAV) was observed to develop, while both the Th1 type (interferon-&ggr;) and Th2 type (interleukin-4 and −10) cytokine expressions decreased in the AKR HG of the tolerant C3H mice treated with both AKR SC plus 200 mg/kg CP, and AKR SC plus 100 mg/kg CP. A second set of skin grafts from donor AKR mice survived for more than 100 days in a tolerogen-specific fashion in all C3H mice treated with AKR SC and 200 mg/kg CP and also accepted the AKR HG for over 200 days, while 80% of the C3H mice treated with AKR SC and 100 mg/kg CP and accepted the AKR HG for more than 200 days. These results strongly suggested the following conclusions: 1) the degree of chimerism can strongly influence the induction of skin and heart allograft tolerance, 2) posttransplant CAV does not develop in the donor HG maintained by chimerism-based CP-induced tolerance, 3) the mRNA expression of both Th1 and Th2 type cytokine decreased in the donor HG maintained by chimerism-based CP-induced tolerance, and 4) the induction of skin allograft tolerance is more difficult than the prevention of posttransplant CAV.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background.Interaction between vascularized xeno-graft and host immune system is thought to occur via Galactose &agr; (1,3) Galactose (Gal&agr; 1,3 gal) structures decorating the xenograft.Methods.We raised anti-Gal&agr; 1,3 gal-BSA polyclonal antibodies in baboons and investigated effect(s) of these antibodies as well as soluble Gal&agr; 1,3 gal-BSA on human naïve natural killer (NK) cell interactions with porcine aortic endothelial cells.Results.We demonstrate that human naïve (unstimulated) NK cells recognize xenogeneic endothelial cells under conditions where binding to the Gal&agr; 1,3 gal structures is minimized by the presence of blocking anti-Gal&agr; 1,3 gal IgG or soluble Gal&agr; 1–3 gal and in the absence of xenoreactive natural antibodies and complement. After xenogeneic encounter both endothelial cells and human NK cells are activated. Endothelial cell activation is rapid and is manifested initially by an intraendothelial calcium transient and subsequently by expression of P-selectin and vascular endothelial cell adhesion molecule-1 on the xenoendothelium surface. NK cell activation is manifested by increased expression of perforin and increased cytotoxicity towards the xenoendothelium. Neither recognition nor activation of the xenoendothelium was affected by the introduction of either anti-Gal&agr; 1,3 gal IgG or soluble Gal&agr; 1–3 gal.Conclusion.Our data provide evidence that innate immune cells, such as NK cells, recognize and activate xenoendothelial cells independently of Gal&agr; 1–3 gal structures and raise the possibility of novel interactive sites on both human naïve NK cells and discordant xenogeneic endothelium.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background.Chronic rejection is the major obstacle to long-term survival of allografts and is associated with graft endothelial cell activation and apoptosis.Recent reports have found an association between graft survival, presence of Th2 cytokines, and expression by endothelial cells of cytoplasmic “protective” molecules that prevent apoptosis and down-regulate the inflammatory process.Methods.Cultured human umbilical vein endothelial cells (HUVEC) were used. Apoptotic cells were detected by staining with FITC-annexinV followed by flow cytometry. Expression of vascular cell adhesion molecule-1, E-selectin, and intercellular adhesion molecule-1 were also measured by flow cytometry. Transcripts were detected by reverse transcription-PCR and quantitation was achieved by co-amplification of competing, internal standard RNA.Results.We demonstrate that exposure of HUVEC to interleukin (IL)-13 for 72 hr afforded partial protection from apoptosis induced by tumor necrosis factor-&agr;/cycloheximide or serum starvation. Pretreatment with IL-13 also modulated induction of E-selectin after acute exposure to tumor necrosis factor-&agr; or IL-1&agr;. Protection was associated with transcription of the genes A1 and A20. Prolonged treatment with IL-13 had minimal proinflammatory effects and did not induce expression of E-selectin or vascular cell adhesion molecule-1 or increase intercellular adhesion molecule-1 above basal levels.Conclusions.Our data provide a possible explanation for the observed association between Th2 cytokines and expression of protective genes in the endothelium of long-surviving allografts and xenografts.

ISSN:0041-1337    

出版商:OVID    

年代:2000

数据来源: OVID