CTLA4Ig gene transfer prolongs survival and induces donor-specific tolerance in a rat renal allograft

Organ transplantation requires lifelong antirejection therapy, which carries the risk of infection and cancer. A revolutionary approach is to transduce the organ graft with immunomodulatory genes to render them tolerated with no need of systemic immunosuppression. Prolonged allograft survival was achieved by adenovirus-mediated transduction of the cold-preserved kidney with sequences encoding CTLA4Ig, a recombinant fusion protein that blocks T cell activation. Organ expression of the transgene was achieved associated with mild infiltration of mononuclear cells in the transfected kidney. Mixed lymphocyte reaction as well as the production of both Thl and Th2 cytokines were reduced. Thus, the gene transfer technique to prolong graft survival is indeed effective and safe and can induce donor-specific unresponsiveness. Pending appropriate large animal testing, ex vivo genetic manipulation of the organ before surgery may hopefully represent a major step forward in human transplant medicine.     

Transfer of "infectious" cardiac allograft tolerance induced by donor-specific transfusion

BACKGROUND: "Infectious tolerance" has been defined as the tolerance induced in a new recipient by the adoptive transfer of cells from a recipient accepting an allograft after anti-CD4 and anti-CD8 monoclonal antibody treatment. A clear understanding of the mechanisms responsible for graft acceptance after donor-specific blood transfusion (DST) has remained elusive. We examined the development and "infectious" nature of immunologic changes resulting in indefinite survival of LEW to DA rat cardiac allografts after DST alone without the need for antibody. METHODS: One hundred x 10(6) LEW splenocytes (SC) as DST were injected intravenously into DA recipients 7 days before LEW cardiac transplantation. Subsequently, 100 x 10(6) SC harvested from a DA recipient 30, 60, or 100 days after graft acceptance were adoptively transferred into lightly gamma-irradiated (450 rad) na?ve DA recipients 24 hours before a second LEW cardiac allograft. Subsequent graft function was determined. RESULTS: Adoptive transfer of SC from the DST-treated DA rats 30 days after LEW heart transplant acceptance into na?ve gamma-irradiated DA rats failed to transfer tolerance to LEW cardiac allografts. However, SC from DA rats bearing LEW hearts for more than 60 days induced indefinite tolerance to all LEW hearts. This infectious tolerance could be adoptively transferred again to a second DA recipient. CONCLUSIONS: DST-generated regulatory cells can downregulate na?ve lymphocytes to promote allograft acceptance. This tolerance can be expanded and serially transferred to a subsequent na?ve cardiac recipient.     

Intrathymic injection of donor alloantigens induces donor-specific vascularized allograft tolerance without immunosuppression.

The induction of donor-specific tolerance could prevent the side effects of immunosuppression while improving allograft survival. Male adult Buffalo (RT1b) rats underwent an intrathymic (IT), portal venous (PV), intrasplenic (IS), or subcutaneous (SQ) injection of 25 x 10(6) major histocompatibility complex (MHC) mismatched Lewis (RT1(1)), UV-B-irradiated Lewis (RT1(1)), ACI (RT1a), or syngeneic Buffalo (RT1b) splenocytes. At the completion of the donor alloantigen injection, 1 mL rabbit anti-rat lymphocyte serum (ALS) was administered intraperitoneally to the Buffalo recipients, and 21 days later a heterotopic Lewis or ACI heart was transplanted. Intrathymic injection of donor alloantigen induced a donor-specific tolerance that allowed the cardiac allograft to survive indefinitely (mean survival time [MST] > 140.7 days) in 84% of the recipients without further immunosuppression, whereas groups receiving antigen injections at other sites (PV, IS, and SQ) plus ALS rejected cardiac allografts in normal fashion (MST approximately 8.0 days). Buffalo recipient rats with long-term surviving Lewis cardiac allografts after Lewis IT injection and ALS subsequently rejected a heterotopic third-party ACI cardiac allograft in normal fashion (MST approximately 7 days), whereas a second Lewis cardiac allograft was not rejected (MST > 116 days). Microchimerism is unlikely because Lewis allograft survival was also prolonged (MST > 38.7 days) in rats receiving UV-B-irradiated splenocytes IT, which cannot proliferate. Survival of Lewis renal allografts was also prolonged, but not indefinitely, in Buffalo recipients possessing a long-term surviving Lewis cardiac allograft (MST approximately 17.6 days versus 7 days for control). This model emphasizes the potential role of exposure of immature thymocytes to foreign donor alloantigens during maturation in the thymic environment for the development of unresponsiveness to an MHC-mismatched donor-specific vascularized allograft.     

CD80mAb协同imDC诱导同种异体大鼠胰十二指肠移植免疫耐受

目的 观察共刺激分子阻断剂CD80单克隆抗体（CD80mAb）在协同未成熟树突细胞（imDC）诱导同种异体大鼠胰十二指肠移植免疫耐受中的作用。方法 建立糖尿病大鼠胰十二指肠移植动物模型；4E5杂交瘤细胞株BABIMC小鼠腹腔注射，抽取腹水，分离纯化后获得CD80mAb；分离供体大鼠骨髓来源DC细胞前体，经GM—CSF、IL-4体外刺激后。再加入IL-10共培养，鉴定为imDC；移植前7d，将2×10^6imDC经静脉途径注射至受体体内，同时分别给予生理盐水1ml、CD80mAb5mg连续14d。结果 四组受体大鼠移植后中位生存时间分别为12．7d、32．4d、50．2d、92．0d，实验组存活时间明显延长；组织学观察发现移植后7dCD80mAb＋imDC组移植物形态尚完整，淋巴细胞浸润减少；混合淋巴细胞反应证实移植后7dCD80mAb＋imDC组供受体间呈低反应性。结论 共刺激分子阻断剂CD80mAb能够协同imDC诱导受体T细胞对移植物的免疫耐受，降低宿主对移植物的急、慢性排斥反应，延长移植物的存活时间。     

Intragraft events preceding chronic renal allograft rejection in a modified tolerance protocol

BACKGROUND: Inbred miniature swine treated for 12 days with high-dose cyclosporine A develop tolerance to histocompatibility complex (MHC) class I-mismatched renal allografts. When this protocol was modified by adding thymectomy before transplant, all animals developed acute rejection. Thereafter, by day 100, one half developed chronic rejection (progression group) and the other half recovered (recovery group). This provides an excellent experimental model to identify the mechanisms of chronic rejection as well as the early changes that may predict chronic rejection. METHODS: We assessed the cellular infiltration, immune activation, humoral immunity, and cell- and antibody-mediated graft injury in the progression and the recovery groups. In addition, we also examined circulating donor reactive cytotoxic T lymphocyte (CTL) and antidonor antibody in both groups. RESULTS: From days 8 to 18 after transplantation, the two groups were indistinguishable. Both showed acute rejection with endarteritis (type II); had IgG and IgM deposition in glomeruli and small vessels; had an infiltrate with similar numbers of T cells, proliferating (PCNA+) and activated (interleukin-2 receptor+) cells; and had a similar degree of parenchymal cell apoptosis [in situ DNA nick-end labeling (TUNEL)+]. However, by days 30 to 60, the two groups could be distinguished by several intragraft features. The recovery group became tolerant and had diminished T-cell infiltration, activation and proliferation, and no detectable antibody deposition. The number of TUNEL+-injured parenchymal cells decreased. In contrast, the progression group showed persistent cell infiltration with activation and proliferation. Significantly prominent TUNEL+ apoptotic parenchymal cells in tubules, glomeruli, peritubular capillaries and arteries were seen from day 30 to day 100. Circulating donor reactive CTL and antidonor class I IgG were detected in the progression group at higher levels than in the recovery group from days 30 to 60. CONCLUSION: In tolerance-induction protocols, unstable tolerance induction is associated with the persistent immunologic activation that mediates immunologic destruction of graft parenchymal cells and chronic rejection. Certain of the described immunopathologic findings (activation, proliferation, apoptosis, and antibody deposition) may be useful in distinguishing the type of rejection, that is, whether the allograft will progress to chronic rejection or recovery.     

Induction of donor-specific unresponsiveness to rat cardiac allograft by donor leukocytes and cyclosporine

Many recent reports have emphasized the importance of donor antigens in the induction of allograft tolerance. This study examines the effect of pretransplant infusion of 10(8) donor leukocytes (DL) combined with peritransplant cyclosporine (CsA) on W/F cardiac allograft survival in Lewis rats. Peritransplant recipient treatment consisted of CsA 20 mg/kg given i.m. on days 0, +1, and +2 relative to heart transplantation. Lewis recipients, 5-8 per group, were pretreated with 10(8) DL with or without peritransplant CsA. A single DL transfusion on day -3 or day -7 prior to transplantation significantly prolonged the mean survival time (MST) of W/F hearts from 7.0 +/- 0.9 days in controls to 12.2 +/- 4.5 days and 12.4 +/- 1.0 days (P less than 0.01), respectively. Two DL infusions on days -7 and -3 or on days -14 and -7 prolonged the MST to 10.6 +/- 1.3 days (P less than 0.02) and 16.4 +/- 2.8 days (P less than 0.001), respectively. The administration of peritransplant CsA alone significantly prolonged W/F heart allograft survival to 43.1 +/- 2.7 days. When pretransplant DL transfusion on day -3 was combined with CsA treatment, 4/8 animals maintained their grafts indefinitely (greater than 100 days). Similarly, DL infusion on day -7 with peritransplant CsA led to indefinite graft survival in 3/5 animals. Administration of DL on days -7 and -3 combined with CsA resulted in indefinite graft survival (greater than 100 days) in 4/6 animals. Transfusion of DL on day -3 alone or in combination with peritransplant CsA, had no effect on a third-party (ACI) heart allograft survival prolongation compared with appropriate controls. To define the underlying mechanisms responsible for donor-specific unresponsiveness in this model, pooled sera and unseparated spleen cells were passively transferred from recipients of long-term cardiac allografts to syngeneic rats receiving donor-type (W/F) or third-party (ACI) cardiac allografts. Transfer of serum (1 ml on days 0, and 1, 0.5 ml on days +2, +3, and +4) from ungrafted recipients of DL on days -14 and -7 led to significant donor graft survival of 9.8 +/- 0.4 days (P less than 0.02) in unmodified hosts. Similarly, passive transfer of serum obtained at 20 and 100 days after transplantation significantly prolonged the MST of donor-type hearts in syngeneic untreated hosts to 11.3 +/- 0.8 and 10.0 +/- 1.1 days, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)     

Pretreatment of renal allograft recipients with immunosuppression and donor-specific blood

The induction of immunologic unresponsiveness to improve renal allograft survival was attempted in 64 patients by the pretransplant administration of donor-specific whole blood or buffy coat in conjunction with continuous azathioprine immunosuppression. All donor/recipient combinations were at least one-haplotype-disparate. Presensitization, defined as a positive Amos or antiglobulin crossmatch or a high-titer (greater than 1:8) B-cell-positive crossmatch, was present in 6 patients and not present in 58 patients. Attempts at desensitization of the already sensitized group were uniformly unsuccessful. Treatment of the 58 nonpresensitized patients resulted in transient sensitization in 2 patients, permanent sensitization in 1 patient, and no evidence of sensitization in 55 patients. Fifty-three patients underwent renal transplantation from the specific blood donor, and only two have experienced renal allograft rejection loss during a mean follow-up period of 22 months (5-45 months); 57% have never experienced a rejection episode. The two-year renal allograft survival rate was 85%. This is significantly (P less than 0.01) better than our historical experience of 64% with one-haplotype living-related transplants. The low rate of sensitization (5%) has permitted almost all patients to undergo eventual renal transplantation from the specific blood donor. This and the low rate of rejection (4%) argues for a modification of the immunologic response, rather than a selecting-out process as the mechanism for improved allograft survival.     

Pretransplant transfusions in cardiac allograft recipients

The role of pretransplant transfusion in cardiac allograft recipients was determined retrospectively in 68 patients. Three groups were studied: group 1 (n = 29) received no pretransplant transfusion, group 2 (n = 15) received transfusion over one year prior to transplantation, and Group 3 (n = 24) received 5 or 10 50-100 ml units of random donor red blood cells or buffy coat 2-4 weeks prior to transplantation. Data were analyzed for survival, number of rejection episodes, and number of infections. Immunosuppression included azathioprine, prednisone, and antithymocyte globulin. Survival in transfused patients (groups 2 and 3) was 68% and 51% at 1 and 5 years, respectively, while in the nontransfused population (group 1) it was 35% and 16%. The incidence of rejection episodes per year of survival was similar in the three groups (group 1: 1.3, group 2: 1.1, group 3: 1.3; P greater than 0.05). The number of infections per year of survival were greater in the transfused patients but this did not achieve statistical significance (group 1: 1.0, group 2: 1.2, group 3: 1.7; P greater than 0.05). Thus, we conclude that cardiac transplant recipients who have received blood transfusions prior to transplantation may have enhanced survival over patients who have not received preoperative transfusions.     

Heart allograft tolerance without development of posttransplant cardiac allograft vasculopathy in chimerism-based, drug-induced tolerance

BACKGROUND: Recently, we have described a drug (cyclophosphamide [CP] plus busulfan [BU])-induced skin allograft tolerance in mice that can regularly overcome fully H-2-mismatched barriers. Using this method, we have investigated whether or not this regimen can prolong the survival of heart allografts and inhibit the development of posttransplant cardiac allograft vasculopathy (CAV). METHODS: The components of the method are intravenous administration of 1 x 108 allogeneic spleen cells on day 0, intraperitoneal injection of 200 mg/kg of CP and 30 mg/kg of BU on day 2, and intravenous injection of T cell-depleted 1 x 107 allogeneic bone marrow cells from the same strain of mice on day 3. Heart grafting was performed on day 28. Chimerism in peripheral blood was followed by flow cytometric analysis, and histological analysis was performed at various times after grafting. RESULTS: In a fully major histocompatability complex (MHC)-mismatched combination of B10.D2 (H-2d, IE+)-->B10 (H-2b, IE-), stable, multilineage-mixed chimerism was observed permanently. B10.D2 heart grafts were accepted permanently in a donor-specific manner, and posttransplant CAV did not develop. CONCLUSIONS: These results demonstrated that the drug-induced tolerance recently established by us can regularly induce a long-lasting heart allograft tolerance without development of CAV.     

Immutol诱导大鼠心脏移植物免疫耐受的研究

目的  探讨Immutol诱导大鼠心脏移植物产生免疫耐受的作用。方法  建立大鼠腹腔异位心脏移植模型。将受体大鼠分成5组：空白对照组（n=6）;DMSO组（n=6）,使用二甲基亚砜(DMSO)给药至移植物停搏;Immutol组（n=6）,使用Immutol给药至移植物停搏;环孢素（CsA）组（n=10）,使用CsA给药20 d后停药;联合实验组（n=13）,使用Immutol给药60 d后停药,CsA给药20 d后停药。观察各组大鼠心脏移植物的存活时间和病理学变化;检测各组大鼠血清白细胞介素（IL）-10、干扰素（IFN）- γ的含量,以及心脏组织的吲哚胺2, 3-双加氧酶（IDO）、纤维蛋白原样蛋白2（Fgl2）的信使核糖核酸（mRNA）表达情况。结果  联合实验组心脏移植物可长期存活,存活时间>180 d,均可诱导产生免疫耐受。联合实验组术后39 d心脏移植物的病理评分明显低于CsA组（P < 0.05）。联合实验组术后9、39 d血清IL-10和IFN- γ含量均明显高于CsA组（均为P < 0.05）,联合实验组IL-10和IFN- γ含量随时间延长逐渐升高。联合实验组术后39 d IDO和Fgl2 mRNA表达量明显高于CsA组（均为P < 0.05）,联合实验组术后IDO的mRNA表达量呈现逐渐升高的趋势。联合实验组术后180 d Fgl2的mRNA表达量明显高于术后9、39 d（均为P < 0.05）。结论  Immutol联合CsA可有效抑制急性排斥反应发生,停药后可诱导移植物长期存活,产生免疫耐受。     

Immature rat myeloid dendritic cells generated in low-dose granulocyte macrophage-colony stimulating factor prolong donor-specific rat cardiac allograft survival

BACKGROUND: Because the differential polarization of T cells in response to antigen presentation is dependent on the maturational state of dendritic cells (DCs), we hypothesized that the adoptive transfer of immature myeloid DCs (iMDCs) would prolong graft survival. METHODS: To evaluate this hypothesis, we studied the effects of transfer of iMDCs and mature myeloid DCs (mMDCs) on rat cardiac allograft survival. RESULTS: Whereas iMDCs that do not express costimulatory molecules induce allogeneic T-cell hyporesponsiveness in coculture studies, mMDCs that express high levels of major histocompatibility complex class II costimulatory and maturation molecules induce a robust allostimulatory T-cell response. Adoptive transfer of Wistar Furth iMDCs, unlike mMDCs, 7 days before cardiac transplantation significantly prolonged graft survival. It was important that adoptive transfer of iMDCs combined with 0.5 mL antilymphocyte serum (ALS) transient immunosuppression on day -7 led to donor-specific permanent graft survival in 50% of recipients. In contrast, adoptive transfer of mMDCs combined with ALS led to graft survival similar to that in recipients treated with ALS alone. Stimulation of CD4 T cells isolated from the spleen of unresponsive allograft recipients with donor antigen resulted in donor-specific hyporesponsiveness and production of interleukin (IL)-10 and transforming growth factor-beta but not IL-4 and interferon-gamma. The tolerant T-cell unresponsiveness was reversed by the addition of IL-2. CONCLUSION: Our data confirming the immunoregulatory effect of immature DCs indicate that induction of transplant tolerance by iMDCs is partly dependent on in vivo generation of regulatory T cells. This finding suggests that immunization with immature donor DCs has therapeutic potential for the induction of transplant tolerance and treatment of autoimmune diseases.     

Intragraft FOXP3 mRNA expression reflects antidonor immune reactivity in cardiac allograft patients

BACKGROUND: Regulatory FOXP3+ T cells control immune responses of effector T cells. However, whether these cells regulate antidonor responses in the graft of cardiac allograft patients is unknown. Therefore, we analyzed the gene expression profiles of regulatory and effector T-cell markers during immunological quiescence and acute rejection. METHODS: Quantitative real-time polymerase chain reaction was used to analyze mRNA expression levels in time-zero specimens (n=24) and endomyocardial biopsies (EMB; n=72) of cardiac allograft patients who remained free from rejection (nonrejectors; n=12) and patients with at least one histologically proven acute rejection episode (rejectors; International Society for Heart and Lung Transplantation [ISHLT] rejection grade>2; n=12). RESULTS: For all analyzed regulatory and effector T-cell markers, mRNA expression levels were increased in biopsies taken after heart transplantation compared with those in time-zero specimens. Posttransplantation, the FOXP3 mRNA levels were higher in EMB assigned to a higher ISHLT rejection grade than the biopsies with grade 0: the highest mRNA levels were detected in the rejection biopsies (rejection grade>2; P=0.003). In addition, the mRNA levels of CD25, glucocorticoid-induced TNF receptor family-related gene, cytotoxic T lymphocyte-associated antigen 4, interleukin-2, and granzyme B were also significantly higher in rejecting EMB than in nonrejecting EMB (rejection grade相似文献