阻断B7诱导大鼠心脏移植免疫耐受的实验研究

目的　研究阻断B7方法诱导大鼠心脏异位移植的免疫耐受。　方法　采用Ono法建立大鼠异位心脏移植模型 ,实验组腹腔注射B7阻断剂CTLA 4Ig,观察大鼠移植的心脏存活天数 ,病理改变和术后IL 2 ,IgG以及IgM含量的变化。　结果　实验组移植的心脏存活时间为 :(31 6 0± 1 82 )d ,对照组 (7 2 5± 0 71)d ,差异有显著性意义 (P <0 0 1)。组织学改变 :实验组见局灶性血管周围或间质内淋巴细胞浸润和局灶性心肌损伤 ,病理分级Ⅰ～Ⅱ级。对照组可见大量淋巴细胞浸润 ,心肌细胞损伤和坏死 ,间质内出血水肿 ,病理分级Ⅳ级。术后IL 2含量实验组比对照组明显下降 ,有显著性差异 ,P <0 0 1。IgG和IgM含量差异无显著性意义 (P >0 0 5 )。　结论　阻断B7能诱导大鼠心脏移植免疫耐受 ,为移植排斥反应提供了新的治疗方法     

RNA干扰阻断B7/CD28共刺激通路在小鼠心脏移植中的抗排斥作用

目的探讨RNA干扰(RNAi)技术阻断B7/CD28共刺激通路对小鼠异体心脏移植排斥反应的影响及其机制。方法经体外转录合成针对CD80 mRNA和CD86 mRNA序列特异性小片段干扰RNA(siRNA),转染供者骨髓来源的树突状细胞(DC),半定量逆转录聚合酶链反应、流式细胞仪检测DC转染CD80siRNA、CD86siRNA前后CD80 mRNA和CD86 mRNA的表达水平以及细胞表面CD80及CD86的表达情况。在小鼠异位心脏移植前7d．经静脉给受者输注经siRNA干扰后的DC(干扰DC组),同时设立同种异体对照组、环孢素A(CsA)治疗组(术后皮下注射CsA 5 mg/d)、同系移植对照组和未干扰DC组(移植前输注未转染DC),观察各组移植心脏的存活时间,对移植物的排斥反应进行病理分级,并测定移植物组织中白细胞介素2(IL-2)、γ干扰素(IFN-γ)及IL-10的mRNA表达水平。结果siRNA转染DC后,其CD80 mRNA及CD86 mRNA的表达受到明显抑制,CD80、CD86的阳性率分别由84%和67%下降至35%和30%。与同种异体对照组和未干扰DC组比较,干扰DC组移植心脏存活时间明显延长(P＜0．01),组织排斥反应病理分级显著降低(P <0．01),移植心脏组织中IL-2 mRNA和IFN-γmRNA的表达水平明显降低(P＜0．01),而IL-10 mRNA的表达水平明显升高(P＜0．01)。结论利用RNAi敲减供者骨髓来源的DC表面B7分子的表达,以阻断B7/CD28共刺激通路,具有抑制小鼠心脏移植排斥反应的作用,其机理可能是通过诱导T淋巴细胞无能并使T辅助细胞分化向T_H2型方向偏移。     

RNA干扰阻断BT／CD28共刺激通路在小鼠心脏移植中的抗排斥作用

目的探讨RNA干扰（RNAi）技术阻断B7／CD28共刺激通路对小鼠异体心脏移植排斥反应的影响及其机制。方法经体外转录合成针对CD80 mRNA和CD86 mRNA序列特异性小片段干扰RNA（siRNA），转染供者骨髓来源的树突状细胞（DC），半定量逆转录聚合酶链反应、流式细胞仪检测DC转染CD80siRNA、CD86siRNA前后CD80 mRNA和CD86 mRNA的表达水平以及细胞表面CD80及CD86的表达情况。在小鼠异位心脏移植前7d，经静脉给受者输注经siRNA干扰后的DC（干扰DC组），同时设立同种异体对照组、环孢素A（CsA）治疗组（术后皮下注射CsA 5mg／d）、同系移植对照组和未干扰DC组（移植前输注未转染DC），观察各组移植心脏的存活时间，对移植物的排斥反应进行病理分级，并测定移植物组织中白细胞介素2（IL-2）、γ干扰素（IFN-γ）及IL-10的mRNA表达水平。结果siRNA转染DC后，其CD80 mRNA及CD86 mRNA的表达受到明显抑制，CD80、CD86的阳性率分别由84％和67％下降至35％和30％。与同种异体对照组和未干扰DC组比较，干扰DC组移植心脏存活时间明显延长（P〈0．01），组织排斥反应病理分级显著降低（P〈0．01），移植心脏组织中IL-2 mRNA和IFN-γ mRNA的表达水平明显降低（P〈0．01），而IL-10 mRNA的表达水平明显升高（P〈0．01）。结论利用RNAi敲减供者骨髓来源的DC表面B7分子的表达，以阻断BT／CD28共刺激通路，具有抑制小鼠心脏移植排斥反应的作用，其机理可能是通过诱导T淋巴细胞无能并使T辅助细胞分化向Tn2型方向偏移。     

Prolonged allograft survival but no tolerance induction by modulating CD28 antibody JJ319 after high-responder rat heart transplantation

BACKGROUND: Allograft rejection depends on T cell immune responses requiring antigen recognition and costimulatory signals through accessory T cell receptors, including CD28. Inhibition of CD28 signaling with a CTLA-4-immunoglobulin (Ig) fusion protein has resulted in immunosuppression and occasional T cell anergy in mouse transplant models, but not in rats. Because this approach also inhibits a potentially tolerizing signal through CTLA-4, selective blockade of CD28 ligation might induce more profound immunosuppression and transplant tolerance. METHODS: The effects of escalating doses of the rat CD28 monoclonal antibody JJ319 on allograft survival were studied after vascularized heterotopic heart transplantation in a high responder strain combination (DA to Lewis). CD28 antigen modulation and circulating antibody levels were monitored by flow cytometry. RESULTS: CD28 antibody JJ319 markedly prolonged cardiac graft survival compared with untreated controls (7 days, range: 6-8). A strictly dose-dependent increase in median graft survival time was demonstrated with a maximum of 36 days (range: 30-40; p <0.001) after the administration of 8 x 1 mg JJ319 i.p. (days -1 to +6 before/after transplantation). However, indefinite graft survival and tolerance could not be induced by JJ319 treatment. At the maximal dose, flow cytometry showed complete down modulation of the CD28 receptor for 10-14 days without T cell depletion in close temporal relation to antibody presence in serum. In vitro, CD28-modulated T cells showed significantly reduced responses to activation. CONCLUSIONS: CD28 antibody JJ319 induces profound immunosuppression after rat heart transplantation, however without development of transplant tolerance. The underlying mechanism seems to be receptor modulation during primary alloantigen recognition. While still potentially applicable clinically, there are no qualitative or quantitative differences to the treatment with CTLA-4/lg or the blockade of CD2 or LFA-1, as reported elsewhere. Thus, a CD28-modulating approach seems not to allow therapeutic exploitation of a tolerizing signal delivered by CTLA-4 but may still be clinically applicable, especially in combined immune interventions.     

OX40 (CD134) blockade inhibits the co-stimulatory cascade and promotes heart allograft survival

BACKGROUND: CD134 (OX40) is a member of the tumor necrosis factor receptor superfamily that is expressed as a late event in T-cell activation and contributes to the generation of immunologic memory. CD134 blockade effectively ameliorates inflammation in models of autoimmune disease, but its role in transplantation has been less well studied. METHODS: The authors used an OX40-immunoglobulin (Ig) fusion protein to examine the contribution of this co-stimulatory molecule to the in vitro alloimmune response and studied the ability of CD134 blockade to prevent cardiac allograft rejection in mouse models of heart transplantation using strains representing both major histocompatibility complex (MHC) (BALB/c to CBA/Ca) and minor histocompatibility complex (mHC) (B10.BR to CBA/Ca) antigen mismatches. RESULTS: CD134 upregulation on in vitro alloactivated T cells was delayed compared with CD69 and CD25, and inhibition of T-cell proliferation was critically dependent on the timing of OX40-Ig administration. Heart allograft survival in a fully allogeneic, MHC-mismatched strain combination was not influenced by CD134 blockade alone, but OX40-Ig treatment in the mHC-mismatched model resulted in long-term graft survival (median survival time extended from 14 days to >100 days). Early mononuclear cell infiltration of the graft was similar in both rejecting and long-surviving heart grafts, but OX40-Ig treatment appeared to delay cellular infiltration. CONCLUSIONS: These results show that CD134-CD134L interaction plays an important role in the co-stimulatory cascade and that blockade of this molecular interaction may be of therapeutic value in helping to prevent allograft rejection.     

Gene therapy-mediated CD40L and CD28 co-stimulatory signaling blockade plus transient anti-xenograft antibody suppression induces long-term acceptance of cardiac xenografts

BACKGROUND: The authors have previously demonstrated that inhibition of CD28 and CD40 ligand (CD40L) co-stimulatory signals by adenovirus-mediated cytotoxic T-lymphocyte-associated (CTL) antigen 4 (A4) immunoglobulin (Ig) and CD40Ig gene therapies induces tolerance or long-term acceptance in rat liver and heart allograft transplantation. In this study, the authors examined whether co-stimulation blockade with a brief course treatment of FK779, a novel leflunomide derivative, would be an ideal strategy for controlling xenograft rejection. METHODS: Hamster hearts were transplanted into Lewis rats. Adenovirus vector coding (Ad) CD40Ig, CTLA4Ig, or LacZ gene (1 x 10(9) plaque-forming units) was administered intravenously to recipient rats 2 days before or immediately after xenografting. FK779 (10 mg/kg/day) was administered orally to recipients for 7 days beginning on day -1. Graft survival, graft histology, and xenoreactive antibodies were examined. RESULTS.: Both untreated and AdLacZ-treated control rats rejected cardiac xenografts, with a median survival time (MST) of 3 days. Co-stimulatory blockade alone by AdCTLA4Ig, AdCD40Ig, or both could not overcome such delayed xenograft rejection (DXR) (MST, 3-4 days). Under a short-course FK779 treatment that suppressed T-cell-independent xenoreactive antibodies, administration of AdCD40Ig (MST, 30.5 days) but not AdCTLA4Ig (MST, 9 days) significantly prolonged xenograft survival as compared with the FK779 monotherapy (MST, 7 days). In contrast, DXR and cellular rejection were controlled successfully and all xenografts were accepted for over 100 days when AdCTLA4Ig and AdCD40Ig were administered under FK779 induction therapy. However, chronic rejection was present in all long-term surviving xenografts. CONCLUSIONS.: Gene therapy-based co-stimulation blockade with FK779 induction treatment seems to be an attractive strategy with which to control xenograft rejection.     

T细胞共刺激信号诱导器官移植免疫耐受的研究进展

人们通过阻断T细胞共刺激信号在小动物实验成功导出抗原特异性的免疫耐受，共刺激信号是T细胞充分活化必需的信号，主要是由CD28和TNF：TNFR两大家族的成员介导的。若阻断此共刺激信号，T细胞不能有效活化和增殖，从而达到免疫耐受状态。     

CD8+CD28-T抑制细胞亚群与肾移植免疫耐受

诱导特异性免疫耐受是临床肾移植中急待解决的问题。CD8^＋CD28-T抑制细胞（TS）所具有的免疫抑制特性，为肾移植后抗排斥治疗提供了新的思路，并为诱导特异性免疫耐受提供了可能性。本文对CD8^＋CD28^-TS细胞的研究历史及近年来新进展作一综述。     

Infectious tolerance mediated by CD8+ T-suppresor cells after UV-B-irradiated donor-specific transfusion and rat heart transplantation

AIMS: CD8+CD28- human T-suppressor cells (Ts), which can be generated in vitro, act directly on APC rendering them tolerogenic to unprimed and primed CD4+ T cells. The aim of this study was to investigate the possibility that CD8+ T cells mediate the induction of tolerance in a heart transplantation model in rodents. MATERIALS AND METHODS: Blood from Lewis rats was UV-B-irradiated and transfused into ACI recipients on days -21, -14, and -7 before heart allograft transplantation on day 0. CD4(+) and CD8(+) T cells were positively selected from ACI rats, which had tolerated Lewis heart allografts for more than 100 days and were adoptively transferred to naive ACI rats pretreated (day -1) with gamma irradiation. These ACI rats underwent transplantation with Lewis hearts 24 hours after adoptive transfer of putative T-suppressor cells. RESULTS: Adoptive transfer of CD8(+) T cells from tolerant ACI to naive ACI rats significantly prolonged Lewis heart mean allograft survival time (MST +/- SD) to 69 +/- 13 days as compared with 15 +/- 1 and 14 +/- 1 days in animals adoptively transferred with CD4+ T cells or untreated controls, respectively (P < .001). Similarly, adoptive transfer of CD8(+) T cells from secondary ACI recipients to naive syngeneic animals also significantly prolonged survival of heart allografts to MST +/- SD of 72 +/- 4 for CD8(+) and 15 +/- 4 days for CD4(+) T cells (P < .001). CONCLUSIONS: These data demonstrate that allogeneic tolerance induced in ACI recipients by treatment with UV-B-irradiated blood from Lewis donors is mediated by CD8+ T-suppressor cells.     

Immunomodulation by blockade of the TRANCE co-stimulatory pathway in murine allogeneic islet transplantation

We explore herein the effect of TNF-related activation-induced cytokine (TRANCE) co-stimulatory pathway blockade on islet survival after allograft transplantation. Expression of TRANCE on murine C57Bl/6 (B6) CD4+ T cells after allogeneic activation was analyzed by fluorescence-activated cell sorter (FACS). The effect of a TRANCE receptor fusion protein (TR-Fc) and anti-CD154 antibody (MR1) on B6 spleen cell proliferation after allogeneic activation was assessed by mixed lymphocyte reaction (MLR). Three groups of B6 mice were transplanted with allogeneic islets (DBA2): Control; short-term TR-Fc-treatment (days 0–4); and prolonged TR-Fc-treatment (days −1 to 13). Donor-specific transfusion (DST) was performed at the time of islet transplantation in one independent experiment. Transplantectomy samples were analyzed by immunohistochemistry. TRANCE expression was upregulated in stimulated CD4+ T cells in vitro . In MLR experiments, TR-Fc and MR1 both reduced spleen cell proliferation, but less than the combination of both molecules. Short-course TR-Fc treatment did not prolong islet graft survival when compared with controls (10.6 ± 1.9 vs. 10.7 ± 1.5 days) in contrast to prolonged treatment (20.7 ± 3.2 days; P  < 0.05). After DST, primary non function (PNF) was observed in half of control mice, but never in TR-Fc-treated mice. Immunofluorescence staining for Mac-1 showed a clear decrease in macrophage recruitment in the treated groups. TRANCE-targeting may be an effective strategy for the prolongation of allogeneic islet graft survival, thanks to its inhibitory effects on co-stimulatory signals and macrophage recruitment.     

Adoptive transfer of transplantation tolerance mediated by CD4+CD25+ and CD8+CD28- regulatory T cells induced by anti-donor-specific T-cell vaccination

Previous studies have shown that vaccinating rodents with anti-donor-specific T cells significantly prolonged allograft survival; however, the putative mechanism of the tolerance remains unclear. In this study, we used the model of heterotopic heart transplantation between the C57BL/6 donor mice and BALB/c recipient mice vaccinated with anti-donor (C57BL/6) or anti-third party (C3H)-specific T cells to determine whether T cells prolong survival of mouse heart allografts and which cells were involved in induction of allograft tolerance. We observed that the mean survival time (MST) of C57BL/6 heart grafts in BALB/c mice vaccinated with anti-C57BL/6 specific T cells (43.1 +/- 4.7 days) was prolonged from that in untreated BALB/c mice (9.5 +/- 1.1 days) or BALB/c mice receiving anti-C3H-specific T cells (10.4 +/- 1.9 days). These results suggested that alloantigen-specific T-cell vaccination significantly prolonged cardiac allograft survival. The CD4+CD25+ or CD8+CD28- T cells purified from splenocytes of BALB/c mice vaccinated with anti-donor-specific T cells proliferated markedly in response to irradiated anti-C57BL/6-specific T cells in vitro. Adoptive transfer of these CD4+CD25+ or CD8+CD28- T cells to na?ve syngenic mice significantly prolonged the survival of heart allografts. These data suggested that anti-donor-specific T-cell vaccination induced development of CD4+CD25+ or CD8+CD28- regulatory T cells, which in turn mediated allogeneic-specific tolerance.     

RNA干扰树突细胞主要组织相容性复合物1表达后诱导抑制性T细胞对小肠移植耐受的影响

目的探讨RNA干扰树突细胞（Dc）组织相容性复合物1（MHC-1）表达后获得的CD8＋CD28-抑制性T细胞（Ts）对小肠移植免疫耐受的的影响。方法通过siRNA干扰DC MHC—I表达后,诱导获得CD8^＋CD28^-Ts。建立由Wistar大鼠移植到SD大鼠的小肠移植模型36例,随机分为A组（转染实验组）、B组（未转染组,注射普通T细胞）和C组（移植对照组,注射生理盐水）。术后14d,每组各随机挑选6例,取移植大鼠小肠和血液标本行移植小肠组织病理学检查．并检测移植大鼠血清TGF-β、IFN-γ水平及回肠黏膜Na^＋-K^＋-ATP酶活性,观察移植大鼠的存活时间。结果术后第14天,A组移植大鼠血清中TGF—β和IFN-γ表达水平高于B、C组（P〈0．05）。A组大鼠肠黏膜Na^＋-K^＋-ATP酶活性为（6．3±1．0）kU／g,明显高于B组的（3．6±0．9）kU／g和C组的（2．9±1．3）kU／g（P〈0．05）。A组移植小肠病理Parks评分分级明显低于B组和C组（P〈0．05）。A、B和C组移植后大鼠中位生存时间分别为32．0、17．5和21．0d,A组存活时间明显优于B组和C组（P〈0．05）。结论将RNA干扰DCMHC—I表达所获得的CD8^＋CD28^-Ts过继小肠移植大鼠．可以减轻移植大鼠的损伤程度．抑制免疫排斥反应．     

Kupffer cell blockade prevents induction of portal venous tolerance in rat cardiac allograft transplantation

Pretransplant portal venous (pv) administration of donor antigen induces allospecific partial tolerance. Although the involved mechanism has not been defined, antigen presentation by Kupffer cells (KC) in the liver is considered to be critical. We evaluated the effect of KC blockade on this pv tolerance induction in Buffalo (RT1b) rats receiving Lewis (RT1(1] cardiac heterotopic allografts. Control rats received no treatment, while experimental animals received 25 X 10(6) ultraviolet B-irradiated (12,000 J/m2) donor spleen cells via either the iv (systemic intravenous) or the pv routes 7 days before transplantation. Gadolinium chloride (GdCl3), a rare earth metal known to inhibit KC phagocytosis, was given (7 mg/kg) 1 and 2 days before pv preimmunization. Cardiac graft prolongation was obtained by pv (MST = 13.3 +/- 1.9 days, n = 6, vs control = 7.3 +/- 0.5 days, n = 6; P less than 0.001) but not by iv preimmunization (7.7 +/- 0.7 days, n = 6, NS vs control). KC blockade abolished the pv tolerance, as indicated by abrogation of graft prolongation (PV + GdCl3 = 8.0 +/- 0.8 days, n = 6, NS vs control). These findings suggest that effective alloantigen uptake by KC in the liver is essential for the induction of pv tolerance in rat cardiac transplantation.     

Co-stimulation blockade targeting CD154 and CD28/B7 modulates the induced antibody response after a pig-to-baboon cardiac xenograft

BACKGROUND: The induced antibodies against Galalpha1,3Gal (Gal) and non-Gal epitopes may contribute to delayed xenograft rejection (DXR). We asked whether blockade of the CD40/CD154 and CD28/B7 co-stimulatory pathways modulates the baboon elicited antibody response to pig Gal and non-Gal antigens. METHODS: Eighteen baboons received heterotopic heart transplants from pigs transgenic for human decay-accelerating factor (n = 13) or membrane cofactor protein (n = 5). Ten reference 'conventional therapy' animals received cyclosporin A, cyclophosphamide and mycophenolate mofetil, with (n = 4) or without (n = 6) anti-CD20. Eight 'co-stimulation blockade' animals received anti-CD154 mAb (IDEC-131) and anti-thymocyte globulin, with (n = 4) or without (n = 4) anti-CD20; two of these animals also received CTLA4-Fc. Anti-alphaGal IgG and IgM, anti-non-Gal antibodies and graft histology were assessed serially. RESULTS: Excluding two early graft failures, median graft survival with conventional therapy was 15 days (range 6 to 36 days, n = 8). Anti-Gal IgG antibody remained low through day 6 to 10, only one graft failure was accompanied by significant rise in anti-Gal IgG, and the anti-non-Gal response was weak (n = 2) or absent (n = 7). However many recipients succumbed with infection (n = 4) or coagulopathy (n = 2); DXR and ICOS+ T cells were prevalent in long-surviving grafts. With co-stimulation blockade, excluding three early graft failures, median graft survival was 7 days (range 6 to 11 days, n = 5). This regimen was very well tolerated, but increased anti-Gal antibody titer within 14 days was associated with graft failure in four of six animals. Although an anti-non-Gal response was present in three of six animals during IDEC-131 monotherapy (one strong, two weak), it was absent in both cases with additional CTLA4-Fc treatment. CONCLUSIONS: As used here, CD154 blockade alone does not completely prevent induction of Gal and non-Gal anti-pig antibodies. Our preliminary data suggest that other co-stimulation pathways, including CD28/B7 and ICOS, are sufficient to mediate high-titer anti-non-Gal antibody to porcine antigens in baboons, and contribute significantly to the pathogenesis of DXR.     

Induction of stable chimerism and transplantation tolerance to rat islet and heart allografts by ultraviolet-B modulation of bone marrow cells.

Ultraviolet-B irradiation (UV-B) (700 J/m2) of BM cells prior to transplantation into lethally gamma-irradiated (1050 rads) allogeneic rats prevents the development of GVHD and results in stable chimerism. This study was developed to determine if UV-B modulation of BMT is useful for preconditioning recipients for the induction of tolerance to donor islets and heart allografts. Lethally irradiated Lewis rats that received UV-B irradiated (700 J/m2) WF BMT (10(8) BM cells) demonstrated stable chimerism without any evidence of GVHD. The stable Lewis chimeras were made diabetic with streptozotocin (STZ) at 28-35 days after BMT and subdivided into 3 experimental groups that received 1000-1200 islets from WF, Lewis, or BN (third-party), respectively. The results showed that group I diabetic Lewis chimeras accepted permanently (greater than 300 days) BM donor WF islets and became normoglycemic. When 3 of 6 Lewis chimeras transplanted with WF islets were rechallenged with WF hearts 60 days after islet grafts, they accepted both islets and cardiac allografts permanently (greater than 240 days). Similarly, the remaining 3 animals accepted Lewis cardiac allografts permanently, thus indicating tolerance to both donor and recipient alloantigens. Group II diabetic chimeras accepted permanently (greater than 300 days) recipient (Lewis) islets. In contrast, group III chimeras rejected acutely (7-8 days) third-party (BN) islets. However, when these animals that rejected BN islets and again became diabetic were retransplanted with BM donor-type (WF) islets, they became permanently normoglycemic (greater than 200 days). This finding emphasizes the specificity of the induction of tolerance in this model and the apparent lack of organ-specific sensitization. To define the underlying mechanism of tolerance, in vivo adoptive transfer of 10(8) spleen cells to naive Lewis or WF recipients, obtained from tolerant Lewis chimeras carrying donor islets and heart allografts, showed no prolongation of cardiac allografts in the unmodified syngeneic hosts, thus questioning the role of suppressor mechanisms in the tolerant rats. Furthermore, cells from the tolerant chimeras that showed no mixed lymphocyte reaction (MLR) response to Lewis or; WF alloantigens failed to suppress anti-Lewis and anti-WF MLR-response in coculture MLR. These results suggest that tolerance to donor alloantigens in the UV-B BMT model is most likely due to selective elimination of anti-BM donor helper or effector cell precursors (clonal deletion) rather than induction of suppressor cell activity. This study demonstrates that this relatively simple and effective approach to modulation of T cells in BM treatment may be potentially useful in the induction of tolerance to donor organs.     

CD28/CD154 blockade prevents autoimmune diabetes by inducing nondeletional tolerance after effector t-cell inhibition and regulatory T-cell expansion

OBJECTIVE—Blocking T-cell signaling is an effective means to prevent autoimmunity and allograft rejection in many animal models, yet the clinical translation of many of these approaches has not resulted in the success witnessed in experimental systems. Improved understanding of these approaches may assist in developing safe and effective means to treat disorders such as autoimmune diabetes.RESEARCH DESIGN AND METHODS—We studied the effect of anti-CD154 and CTLA4-Ig on diabetes development, and the requirements to induce tolerance in nod.scid mice after transfer of transgenic β-cell reactive BDC2.5.NOD T-cells.RESULTS—Nod.scid recipients of diabetogenic BDC2.5.NOD cells were protected indefinitely from diabetes by a short course of combined costimulation blockade, despite the continued diabetogenic potential of their T-cells. The presence of pathogenic T-cells in the absence of disease indicates peripheral immune tolerance. T-cell maturation occurred in protected recipients, yet costimulation blockade temporarily blunted early T-cell proliferation in draining pancreatic nodes. Tolerance required preexisting regulatory T-cells (Tregs), and protected recipients had greater numbers of Tregs than diabetic recipients. Diabetes protection was successful in the presence of homeostatic expansion and high T-cell precursor frequency, both obstacles to tolerance induction in other models of antigen-specific immunity.CONCLUSIONS—Immunotherapies that selectively suppress effector T-cells while permitting the development of natural regulatory mechanisms may have a unique role in establishing targeted long-standing immune protection and peripheral tolerance. Understanding the mechanism of these approaches may assist in the design and use of therapies for human conditions, such as type 1 diabetes.Reagents that bind T-cell surface molecules and interfere with T-cell activation and effector function hold the promise of being safe and effective therapies for organ transplantation and autoimmunity. Disruption of CD154, CD28, and LFA-1 pathways, either by biological agent or by genetic means, can prolong allograft survival and prevent autoimmune disease in murine models and at times (re)establish immune tolerance (1–7). Type 1 diabetes is caused by the activation of peripheral β-cell autoreactive T-cells that have escaped central tolerance (8). In the NOD mouse model of type 1 diabetes, treating juvenile NOD mice with anti-CD154, CTLA4-Ig, or anti-B7.2 to interrupt the CD154:CD40 and CD28:B7 costimulatory pathways provides long-term disease protection (9,10). Although this is purported to result from preventing auto-aggressive T-cell activation, the full immunological mechanisms of how disease is prevented and protection is maintained are unclear (9–11). Studies involving CD154 knockout NOD mice (which are protected from diabetes) and B7–1/B7–2-deficient and CD28-deficient mice (which have exacerbated spontaneous diabetes due the lack of Tregs) provide evidence for the importance of T-cell regulatory-to-effector (Treg:Teff) balance in the development of autoimmune diabetes and the maintenance of self-tolerance (13–17).The translation of agents that target T-cells for use in human conditions has been trying. In part, this is due to unforeseen side effects in preclinical and clinical testing, including thromboembolic events with some anti-CD154 antibodies and lethal cytokine storm with superagonist anti-CD28 antibodies (18,19). Yet many other biological agents that interfere with T-cell signaling, such as anti-CD3, anti-CD25, CTLA-4/LEA29Y, and anti-LFA-1, have impressive safety profiles in clinical trials in autoimmunity and/or transplantation (10–22).One of our goals was to better understand how therapeutic strategies induce long-term immune protection of and immune tolerance to allo- and autoimmune targets. We studied the effect of costimulation blockade on diabetes development after the adoptive transfer BDC2.5.NOD CD4⁺ T-cells. BDC2.5 T-cells recognize a yet-unidentified β-cell antigen presented by IA^g7, a unique class II molecule found in NOD and derivative-strain mice (23–25). Although BDC2.5.NOD (NOD.BDC) mice harbor a monoclonal population of β-cell–reactive T-cells and possess a substantial peri-insulitis, they rarely become diabetic because of inducible costimulatory molecule (ICOS)-, transforming growth factor-β(TGF-β)–, and programmed death (PD)-1 Treg–dependent mechanisms (26–28). Yet adoptively transferring their T-cells to major histocompatibility complex (MHC)–matched lymphopenic recipients results in rapid β-cell destruction and diabetes (24,29).Herein, we show that diabetes resulting from adoptively transferred BDC.NOD T-cells can be prevented by a brief course of anti-CD154 and CTLA4-Ig. This therapy is successful in the presence of high T-cell precursor frequency and antigen-specific and homeostatic T-cell activation, known barriers to costimulation blockade-mediated tolerance. Long-term protected recipients harbor T-cells capable of causing diabetes, and immune tolerance is dependent on preexisting Tregs. Understanding how nondeletional peripheral tolerance can be generated by therapeutic means is likely an important step in developing safe and effective approaches to prevent and treat autoimmune conditions such as type 1 diabetes.     

Influence of gadolinium-induced kupffer cell blockade on portal venous tolerance in rat skin allograft transplantation

BACKGROUND: Intraportal injection of donor antigens delays rejection of allografts (portal venous tolerance). The study aimed to investigate the possible influence of prior gadolinium chloride (Gd)-induced Kupffer cell blockade on tolerance to non-vascularized skin allografts induced by means of donor-specific intraportal blood transfusion. MATERIALS AND METHODS: Wistar rats (n = 10) were used as donors and Sprague-Dawley rats (n = 70) as recipients of a non-vascularized skin graft. Recipients were divided into groups according to the manipulations prior to transplantation, as follows: (1) no manipulation; (2) donor-specific intrajugular blood transfusion; (3) donor-specific intraportal blood transfusion; (4) Gd administration and donor-specific intrajugular blood transfusion; (5) Gd administration and donor-specific intraportal blood transfusion; (6) Gd administration, and (7) intraportal saline infusion. In a first set of experiments, these manipulations were performed once. In a second set of experiments, the same manipulations were performed twice. Skin allograft was performed 7 days after the last manipulation in all groups. RESULTS: Group 3 showed the highest skin graft survival, particularly after repeated blood transfusion. Graft survival in this group was significantly higher than in any other group. Conversely, group 5 showed the lowest graft survival, particularly after repeated blood transfusion. Graft survival in this group was significantly lower than that of groups 1, 2, 3 and 7. CONCLUSIONS: In this model of skin allograft transplantation, Gd administration abrogates and can even reverse the tolerogenic effect of repeated donor-specific intraportal blood transfusion.     

Simultaneous heart and kidney transplantation from a single donor

Objective: There are no guidelines to establish the indications and contraindications for a simultaneous heart and kidney transplantation. We report our single-institutional experience with simultaneous heart and kidney transplantation. Methods: Retrospective chart review. Results: Between 1995 and 2006, 13 patients with co-existing end-stage heart and renal failure underwent simultaneous heart and kidney transplantation at the authors’ hospital. Heart failure was secondary to dilated cardiomyopathy in five patients, ischemic cardiomyopathy in three, cardiac allograft vasculopathy in two, and congenital heart disease, cardiac allograft failure, and acute myocarditis each in one. Renal failure was secondary to glomerulonephritis in six patients, heart failure in two, cyclosporine nephropathy in three, hypertension in one, and systemic lupus erythematosus in one. Eight patients were in UNOS status IA and five patients in UNOS status II before transplantation. The 30-day mortality rate and in-hospital mortality rate were 15% and 38%. Of eight patients in UNOS status IA, seven patients have lived beyond 30 days and three (38%) beyond 1 year. Of five patients in UNOS status II, four patients have lived beyond 30 days and four (80%) beyond 1 year. Patients in UNOS status IA had high rates of previous cardiac surgery, cardiac allograft rejection, and major renal allograft complications. Conclusions: Although simultaneous heart and kidney transplantation continues to be a viable option for patients with co-existing end-stage heart and renal failure, the results do not match those of isolated heart transplantation. The clinical outcomes were not satisfactory in UNOS status IA patients with previous cardiac surgery.     

1O-羟基喜树碱和环孢素A诱导异基因大鼠心脏移植受者免疫耐受的实验研究

目的以中药制剂10-羟基喜树碱(HCPT)和环孢素A(CsA)诱导异基因大鼠心脏移植受者免疫耐受,并探讨免疫耐受的特异性和形成机制.方法以纯系SD大鼠为供者,纯系Wis-tar大鼠为受者行异体颈部心脏移植.将移植后50只受者大鼠随机分成5组,分别接受不同剂量HCPT、CsA或二者联合应用.A组接受安慰剂.B组接受HCPT 1.0mg·kg-1·d-1,腹腔注射.C组接受HCPT 2.0 mg·kg-1·d-1,腹腔注射.E组接受CsA10.0 mg·kg·d-1,导管灌胃.F组联合应用HCPT和CsA,方法剂量同B组和E组.心脏移植物长期存活受者术后60 d停用免疫抑制剂,120 d同时行供者来源(SD)大鼠和无关供者(SHR)大鼠皮肤移植.结果3只C组大鼠和5只F组大鼠心脏移植术后停用免疫抑制剂长期存活超过730 d.8块SD大鼠皮肤移植物长期存活超过610 d,而8块SHR大鼠皮肤均被排斥,平均存活时间(4.50±1.25)d.结论大剂量HCPT或小剂量HCPT与CsA联合应用可诱导异基因大鼠心脏移植受者免疫耐受,且形成的免疫耐受具有明确的抗原特异性.