Critical role of proinflammatory cytokine IL-6 in allograft rejection and tolerance

The proinflammatory cytokine IL-6 plays an important role in controlling T-cell differentiation, especially the development of Th17 and regulatory T cells. To determine the function of IL-6 in regulating allograft rejection and tolerance, BALB/c cardiac grafts were transplanted into wild-type or IL-6-deficient C57BL/6 mice. We observed that production of IL-6 and IFN-γ was upregulated during allograft rejection in untreated wild-type mice. In IL-6-deficient mice, IFN-γ production was greater than that observed in wild-type controls, suggesting that IL-6 production affects Th1/Th2 balance during allograft rejection. CD28-B7 blockade by CTLA4-Ig inhibited IFN-γ production in C57BL/6 recipients, but had no effect on the production of IL-6. Although wild-type C57BL/6 recipients treated with CTLA4-Ig rejected fully MHC-mismatched BALB/c heart transplants, treatment of IL-6-deficient mice with CTLA4-Ig resulted in graft acceptance. Allograft acceptance appeared to result from the combined effect of costimulatory molecule blockade and IL-6-deficiency, which limited the differentiation of effector cells and promoted the migration of regulatory T cells into the grafts. These data suggest that the blockade of IL-6, or its signaling pathway, when combined with strategies that inhibit Th1 responses, has a synergistic effect on the promotion of allograft acceptance. Thus, targeting the effects of IL-6 production may represent an important part of costimulation blockade-based strategies to promote allograft acceptance and tolerance.     

Different mechanisms of cardiac allograft rejection in wildtype and CD28-deficient mice.

Although CD28 blockade results in long-term cardiac allograft survival in wildtype mice, CD28-deficient mice effectively reject heart allografts. This study compared the mechanisms of allogeneic responses in wildtype and CD28-deficient mice. Adoptive transfer of purified CD28-deficient T cells into transplanted nude mice resulted in graft rejection. However, this model demonstrated that the allogeneic T cell function was severely impaired when compared with wildtype T cells, despite similar survival kinetics. Cardiac allograft rejection depended on both CD4+ and CD8+ T cell subsets in CD28-deficient mice, whereas only CD4+ T cells were necessary in wildtype recipients. These results suggested that CD8+ T cells were more important in CD28-deficient than wildtype mice. In addition to the CD8+ T cell requirement, allograft rejection in CD28-deficient mice was dependent on a sustained presence of CD4+ T cells, whereas it only required the initial presence of CD4+ T cells in wildtype mice. Taken together, these data suggest that CD4+ T cells from CD28-deficient mice have impaired responses to alloantigen in vivo, thus requiring long-lasting cooperation with CD8+ T cell responses to facilitate graft rejection. These results may help to explain the failure to promote graft tolerance in some preclinical and clinical settings.     

Interleukin-9 promotes eosinophilic rejection of mouse heart allografts

BACKGROUND: Eosinophils participate in allograft rejection when donor-reactive helper T lymphocytes are T-helper type 2 (Th2)-biased. Whereas the involvement of interleukin (IL)-4 and IL-5 in these forms of rejection is well established, the role of IL-9, another Th2-type cytokine promoting eosinophilia, has not been determined. METHODS: We first used real-time polymerase chain reaction to quantify IL-9 mRNA in rejected allografts in a mouse model of fully mismatched heart transplantation in which recipients were devoid of CD8 T cells and developed a Th2 alloimmune response. We then compared allograft survival in wild-type versus IL-9-deficient mice depleted of CD8 T cells. Finally, we compared the fate of major histocompatibility complex class II-mismatched cardiac transplants from wild-type versus IL-9 transgenic donors to determine the influence of IL-9 overexpression within the graft. RESULTS: The Th2 alloimmune response in CD8-deficient mice was associated with the accumulation of IL-9 mRNA in the rejected graft. In IL-9-deficient recipients depleted of CD8 T cells, eosinophil infiltration of heart allografts did not develop, but rejection still occurred. In the major histocompatibility complex class II disparate model, heart allografts from IL-9 transgenic donors were acutely rejected, whereas grafts from wild-type donors did not develop rejection. Acute rejection of IL-9 transgenic hearts was associated with massive eosinophil infiltration and prevented by neutralization of either IL-4 or IL-5. CONCLUSION: IL-9 is critically involved in heart transplant eosinophilia in conjunction with IL-4 and IL-5.     

Donor IL-6 deficiency evidently reduces memory T cell responses in sensitized transplant recipients

BackgroundResistance of tolerance induction in sensitized transplantation is mainly caused by generation of memory T cells. It is unknown whether alteration of graft niche such as level of pro-inflammatory cytokines can affect generation of memory T cells.MethodsIL-6 deficient or wild-type (WT) C57BL/6 heart grafts were transplanted into pre-sensitized wild-type BALB/c recipients. Frequencies of memory T cells in the peripheral blood, grafts, and spleen were evaluated.ResultsWe revealed that deficiency of donor IL-6 could significant prolong sensitized allograft survival. Compared with counterpart of WT group, frequency of effector memory CD4 + T cells (CD4 + CD44 + CD62L-) in the peripheral blood was significantly lower in the IL-6 KO group (p = .026) at day 3 post-transplantation. Frequency of effector memory CD8 + T cells (CD8 + CD44 + CD62L-) in the peripheral blood was significantly lower in the IL-6 KO group (p < .0001) at day 3 post-transplant in comparison to that of WT group. No significant difference of central memory T cells was found between these groups. Histology demonstrated that deficiency of donor pro-inflammatory cytokine IL-6 (IL-6 KO group) preserved cardiac architecture with a mild infiltration of lymphocytes, whereas wild-type donor (control group) caused an evident lymphocytic infiltration within myocardial fibers of grafts and destruction of cardiac structure.ConclusionDeficiency of pro-inflammatory IL-6 of donor graft could effectively prolong sensitized allograft survival, which was caused by a remarkable decrease of peripheral memory T cells rather than central memory T cells. This unveiled mechanism of targeting IL-6 signaling pathway might provide a novel insight into preventing allograft rejection for sensitized transplant recipients.     

Recipient Myd88 Deficiency Promotes Spontaneous Resolution of Kidney Allograft Rejection

The myeloid differentiation protein 88 (MyD88) adapter protein is an important mediator of kidney allograft rejection, yet the precise role of MyD88 signaling in directing the host immune response toward the development of kidney allograft rejection remains unclear. Using a stringent mouse model of allogeneic kidney transplantation, we demonstrated that acute allograft rejection occurred equally in MyD88-sufficient (wild-type [WT]) and MyD88^−/− recipients. However, MyD88 deficiency resulted in spontaneous diminution of graft infiltrating effector cells, including CD11b⁻Gr-1⁺ cells and activated CD8 T cells, as well as subsequent restoration of near-normal renal graft function, leading to long-term kidney allograft acceptance. Compared with T cells from WT recipients, T cells from MyD88^−/− recipients failed to mount a robust recall response upon donor antigen restimulation in mixed lymphocyte cultures ex vivo. Notably, exogenous IL-6 restored the proliferation rate of T cells, particularly CD8 T cells, from MyD88^−/− recipients to the proliferation rate of cells from WT recipients. Furthermore, MyD88^−/− T cells exhibited diminished expression of chemokine receptors, specifically CCR4 and CXCR3, and the impaired ability to accumulate in the kidney allografts despite an otherwise MyD88-sufficient environment. These results provide a mechanism linking the lack of intrinsic MyD88 signaling in T cells to the effective control of the rejection response that results in spontaneous resolution of acute rejection and long-term graft protection.     

Absence of host B7 expression is sufficient for long-term murine vascularized heart allograft survival

CD28 antagonists have been shown to promote long-term graft survival and induce donor-specific tolerance. In this study, the role of CD28/B7 costimulation and the relative importance of host versus donor B7 expression in allograft rejection was assessed in a murine abdominal vascularized heterotopic heart transplant model. Wild-type, CD28-deficient, or B7-1/B7-2-deficient C57BL/6 (B6) mice were grafted with allogeneic wild type or B7-1/B7-2-deficient hearts. The results demonstrate allogeneic heart grafts survive long-term in mCTLA4Ig-treated B6 and untreated B7-1/B7-2-deficient B6 recipients but not CD28KO B6 mice. B7-1/B7-2KO B6 recipients treated with anti-CD28 (PV-1) or recombinant human IL-2 rejected the heart transplants indicating that these mice are immunologically competent to reject grafts if costimulatory signals are supplied or bypassed. Finally, there was no difference in rejection between normal animals transplanted with wild-type versus B7-1/B7-2-deficient hearts. These results support a critical role for B7-expressing host antigen presenting cells in the rejection of heart allografts in mice and differences among B7KO and CD28KO animals.     

A major role for host MHC class I antigen presentation for promoting islet allograft survival

The purpose of this study was to determine the role for CD8 T cells versus generalized MHC class I-restricted antigen presentation in islet allograft rejection and tolerance. Diabetic C57BI/6 (B6, H-2(b)) controls, C57BI/6 CD8-deficient (CD8 KO), or MHC class I-deficient C57BI/6 (beta 2m KO) recipients were grafted with allogeneic BALB/c (H-2(d)) islets. Islet allografts were acutely rejected in untreated B6, CD8 KO, and in beta 2m KO mice, indicating that neither CD8 T cells nor host MHC class I is required for allograft rejection. We then determined the efficacy of costimulation blockade in these same strains. Costimulation blockade with anti-CD154 therapy facilitated long-term islet allograft survival in both B6 and in CD8 KO recipients. However, anti-CD154 treated beta 2m KO recipients were completely refractory to anti-CD154 therapy; all treated animals acutely rejected islet allografts with or without therapy. Also, anti-NK1.1 treatment of wild-type B6 mice abrogated graft prolongation following anti-CD154 therapy. Taken together, results show a dramatic distinction between two forms of MHC class I-restricted pathways in allograft prolongation. Although anti-CD154-induced allograft survival was CD8 T-cell independent, an intact host MHC class I-restricted (beta 2m-dependent) pathway is nevertheless necessary for allograft survival. This pathway required NK1.1+ cells, implicating NK and/or NKT cells in promoting allograft prolongation in vivo.     

CD8(+) T cells resistant to costimulatory blockade are controlled by an antagonist interleukin-15/Fc protein

BACKGROUND: Although permanent engraftment is often achieved with new therapeutics, chronic rejection and graft failure still occur. As the importance of CD8(+) T cells in rejection processes has been underlined in various transplant models, and as interleukin (IL)-15 is involved in the activation of CD8(+) T cells, we hypothesize that CD8(+) T cell "escape" from costimulation blockade might be a IL-15/IL-15R dependent process. METHODS: In a murine islet allograft model employing a fully major histocompatibility complex-mismatched strain combination of Balb/c donors to CD4 C57BL/6 recipients, a monotherapy with the IL-15 antagonist, IL-15 mutant/Fcgamma2a, or the costimulatory blockade molecule, CTLA4/Fc, was used. In addition to monitoring graft survival, infiltration of alloreactive immune cells was analyzed by histology and immunohistochemistry, and alloimmune response of proliferative CD8(+) T cells was measured in vivo. RESULTS: Sixty percent of the recipients treated with CTLA4/Fc acutely rejected their islet allograft, comparable to untreated control animals (50% survival). In contrast, the IL-15 antagonist proved to be highly effective, with 100% of recipients accepting their allograft. Immunohistology study demonstrated a remarkable decrease of CD8(+) T-cell intragraft infiltration in IL-15 mutant/Fcgamma2a treated animals with well-preserved islet architecture and a reduced frequency of proliferating alloreactive CD8(+) T cells in comparison with that of untreated and CTLA4/Fc treated groups. CONCLUSIONS: In this study, we determined the efficacy and potential therapeutic benefit of the IL-15 antagonist on CD4-independent CD8(+) T-cell responses to alloantigens. Targeting the IL-15/IL-15R pathway represents a potent strategy to prevent rejection driven by CD8(+) T cells resistant to costimulation blockade.     

Allergic Conjunctivitis Renders CD4+ T Cells Resistant to T Regulatory Cells and Exacerbates Corneal Allograft Rejection

Allergic diseases rob corneal allografts of immune privilege and increase immune rejection. Corneal allograft rejection in BALB/c allergic hosts was analyzed using a short ragweed (SWR) pollen model of allergic conjunctivitis. Allergic conjunctivitis did not induce exaggerated T‐cell responses to donor C57BL/6 (B6) alloantigens or stimulate cytotoxic T lymphocyte (CTL) responses. Allergic conjunctivitis did affect T regulatory cells (Tregs) that support graft survival. Exogenous IL‐4, but not IL‐5 or IL‐13, prevented Treg suppression of CD4⁺ effector T cells isolated from naïve mice. However, mice with allergic conjunctivitis developed Tregs that suppressed CD4⁺ effector T‐cell proliferation. In addition, IL‐4 did not inhibit Treg suppression of IL‐4Rα^?/? CD4⁺ T‐cell responses, suggesting that IL‐4 rendered effector T cells resistant to Tregs. SRW‐sensitized IL‐4Rα^?/? mice displayed the same 50% graft survival as nonallergic WT mice, that was significantly less than the 100% rejection that occurred in allergic WT hosts, supporting the role of IL‐4 in the abrogation of immune privilege. Moreover, exacerbation of corneal allograft rejection in allergic mice was reversed by administering anti‐IL‐4 antibody. Thus, allergy‐induced exacerbation of corneal graft rejection is due to the production of IL‐4, which renders effector T cells resistant to Treg suppression of alloimmune responses.     

CD25+CD4+ regulatory T cells develop in mice not only during spontaneous acceptance of liver allografts but also after acute allograft rejection

BACKGROUND: Liver grafts transplanted across a major histocompatibility barrier are accepted spontaneously and induce donor specific tolerance in some species. Here, we investigated whether liver allograft acceptance is characterized by, and depends upon, the presence of donor reactive CD25CD4 regulatory T cells. METHODS: CD25 and CD25CD4 T cells, isolated from CBA. Ca (H2) recipients of C57BL/10 (B10; H2) liver and heart allografts 10 days after transplantation, were transferred into CBA. Rag1 mice to investigate their influence on skin allograft rejection mediated by CD45RBCD4 effector T Cells. RESULTS: Fully allogeneic B10 liver allografts were spontaneously accepted by naive CBA.Ca recipient mice, whereas B10 cardiac allografts were acutely rejected (mean survival time=7 days). Strikingly, however, CD25CD4 T cells isolated from both liver and cardiac allograft recipients were able to prevent skin allograft rejection in this adoptive transfer model. Interestingly, CD25CD4 T cells isolated from liver graft recipients also showed suppressive potency upon adoptive transfer. Furthermore, depletion of CD25CD4 T cells in primary liver allograft recipients did not prevent the acceptance of a secondary donor-specific skin graft. CONCLUSIONS: Our data provide evidence that the presence of CD25CD4 regulatory T cells is not a unique feature of allograft acceptance and is more likely the result of sustained exposure to donor alloantigens in vivo.     

Differential effects of exogenous interleukin-10 on cardiac allograft survival: inhibition of rejection by recipient pretreatment reflects impaired host accessory cell function

BACKGROUND: There have been conflicting reports of the influence of exogenous mammalian interleukin (IL)-10 on immune reactivity. These findings may reflect the pleiotropic effects of IL-10 on the functions of antigen-presenting cells and immune effector cells. The purpose of this study was to extend observations of the influence of the cytokine on organ allograft survival and to investigate its effects on the function of accessory and immune effector cells in a mouse cardiac transplant model. METHODS: C3H (H2k) recipients of heterotopic vascularized B10 (H-2b) heart allografts were treated with recombinant (r) mouse IL-10 over a wide range of doses (0.2-200 microg/day), either before the transplant (days -3, -2, -1), peri-operatively (days -1, 0, 1), or after the transplant (days 0-6). Anti-donor cytotoxic T lymphocyte activity of host spleen and graft-infiltrating cells, and circulating complement-dependent cytotoxic antibody titers were determined by isotope release assays. Mixed leukocyte reactions were used to determine the influence of IL-10 on the function of antigen-presenting cells and allogeneic responder T cells. RESULTS: Recipient pre-transplant administration of IL-10 (days -3, -2, -1) prolonged graft survival at all doses tested. Donor pretreatment with IL-10 (25 microg/day; days -3, -2, -1) was also effective, but less. A pre-transplant or perioperative course of IL-10, however, did not significantly affect the immunosuppressive action of tacrolimus given on days 0-6. If given only after the transplant, IL-10 either had no effect on graft survival or (at high dosage) accelerated rejection and prevented the immunosuppressive effect of cyclosporine. Pretransplant treatment of graft recipients with IL-10 reduced splenic anti-donor cytotoxic T lymphocyte activity and the incidence of graft-infiltrating CD8+ cells. There was no significant effect on circulating alloantibody titers. MLR assays revealed that preincubation of responder cells, but not stimulator spleen cells with IL-10, inhibited T cell proliferation, whereas addition of IL-10 after the start of culture modestly enhanced proliferation. Preincubation of purified T responders with IL-10 showed no inhibitory effect. CONCLUSION: The modest and opposing effects of exogenous IL-10 on organ allograft survival are dependent on timing and dosage. Recipient pretreatment prolongs graft survival. This finding, together with the MLR results, suggest that IL-10 inhibits the function of host immune accessory cells and that the direct pathway of alloantigen presentation may be less susceptible to inhibition by IL-10.     

Immune responses of graft mesenteric lymph node in small bowel transplantation

BACKGROUND: The high proportions of lymphoid tissues are thought to be one of the underlying factors inducing severe allograft rejection following small bowel transplantation. Mesenteric lymph nodes (MLN) contained in the intestinal graft are not only a source of donor-derived professional antigen-presenting cells, but also offer a field for immune interaction between donor and host cells. We investigated immune responses in graft MLNs with or without FK506 to develop a novel strategy to control small bowel allograft rejection. MATERIALS AND METHODS: Heterotopic small bowel transplantations were performed from Brown Norway donors to Lewis recipients. Changes in population of lymphocytes, expressions of costimulatory molecules, apoptosis, and cytokine profiles in graft MLNs were evaluated. RESULTS: The increase in apoptotic cells and cytokine responses relating to rejection in the graft MLNs developed prior to those in graft jejunum. While donor lymphocytes in graft MLNs were rapidly replaced to host-derived lymphocytes independent of FK treatment, increase in CD8(+) T cells in host population was seen only in recipients without FK506 treatment. The expressions of B7 molecules on donor cells in graft MLNs were significantly lower in the recipients with FK treatment. CONCLUSIONS: Immune responses in graft MLNs have significant impact on the outcome of the small bowel allograft. Apoptosis of graft MLN cells was well correlated with and ahead of progression of acute rejection. Modulation of costimulatory molecules on donor-derived MLN cells in the allograft and specific suppression of host CD8(+) T cells are possible ways to control severe rejection after allogeneic small bowel transplantation.     

Inhibition of chronic rejection and development of tolerogenic T cells after ICOS-ICOSL and CD40-CD40L co-stimulation blockade

BACKGROUND.: Blockade of the CD40-CD40L pathway results in long-term allograft survival but does not prevent chronic rejection. ICOS-ICOSL are members of the CD28-B7 family that play an important role in T-cell activation. METHODS.: The authors analyzed the effect of single or combined treatment with an anti-ICOS monoclonal antibody and CD40 immunoglobulin (Ig) on acute and chronic rejection of heart allografts in rats. RESULTS.: Treatment with anti-ICOS resulted in a modest but significant prolongation of allograft survival. Treatment with CD40Ig resulted in long-term graft survival but the cardiac grafts developed chronic rejection lesions. Combined CD40Ig+anti-ICOS treatment led to indefinite graft survival in all recipients and a significant decrease of chronic rejection lesions compared with CD40Ig alone. Importantly, four of the seven CD40Ig+anti-ICOS-treated recipients showed a complete absence of chronic rejection lesions, whereas all of the CD40Ig-treated recipients showed chronic rejection. The CD40Ig+anti-ICOS group also showed significant decreased graft infiltration, decreased antidonor cytotoxic T-lymphocyte activity, and decreased alloantibodies compared with the CD40Ig-treated group. Adoptive transfer of splenocytes indefinitely prolonged allograft survival, whereas those depleted of T cells did not, suggesting the development of T-regulatory mechanisms. CONCLUSIONS.: These data indicate that the chronic rejection mechanisms that are CD40-CD40L independent are ICOS-ICOSL dependent. These results were obtained with conservation of cognate immune responses and development of tolerogenic T cells.     

移植抗原特异性转基因CD8+T细胞对白细胞介素2的依赖性

目的研究白细胞介素2（IL-2）在调节移植抗原特异性转基因CD8^＋T细胞介导的免疫排斥反应中的作用。方法将经荧光染科CFSE标记后的C57BL／6小鼠和2CTg小鼠（CD4敲除鼠）淋巴细胞分别植入经致死剂量γ射线照射过的两组DBA／2J小鼠体内，检测CD4^＋与CD8^＋T细胞在体内分裂增殖的时相，并用胞浆内IL-2标志染色方法测定活化后T细胞表达IL-2的能力。以Balb／c小鼠为供者，糖尿病2CTg小鼠和2C Tg-IL-2KO小鼠（IL-2敲除鼠）为受者，进行胰岛细胞移植。观察CD8^＋ T细胞在介导移植排斥中的作用。结果DBA／2J小鼠输注了C57BL／6小鼠的淋巴细胞后，CD4^＋与CD8^＋T细胞分裂增殖均非常明显，前者表达大量IL-2，后者则不表达。DBA／2J小鼠输注了2CTg小鼠的淋巴细胞后。在完全没有CD4^＋T细胞存在的情况下，CD8^＋T细胞仍明显分裂增殖并大量表达IL-2。2CTg和2CTg—IL-2KO小鼠移植胰岛细胞后，前者迅速发生排斥反应，胰岛移植物的平均存活时间仅为8d，而后者胰岛移植物的平均存活时间〉50d。结论CD8^＋T细胞在产生和利用IL-2时有很大的可塑性。CD4^＋T细胞存在时，CD8^＋T细胞能有效利用CD4^＋T细来源的IL-2进行分裂增殖，在缺乏CD4^＋T细胞时，则利用自身来源的IL-2进行分裂增殖；移植抗原特异性CD8^＋T细胞的效应功能完全依赖于IL-2，排斥反应由CD8^＋T细胞介导时，阻断IL-2／IL-2受体通路可诱导移植物长期存活。     

Multiple pathways to allograft rejection

Allograft rejection results from a complex process involving both the innate and acquired immune systems. The innate immune system predominates in the early phase of the allogeneic response, during which chemokines and cell adhesion play essential roles, not only for leukocyte migration into the graft but also for facilitating dendritic and T-cell trafficking between lymph nodes and the transplant. This results in a specific and acquired alloimmune response mediated by T cells. Subsequently, T cells and cells from innate immune system function synergistically to reject the allograft through nonexclusive pathways, including contact-dependent T cell cytotoxicity, granulocyte activation by either Th1 or Th2 derived cytokines, NK cell activation, alloantibody production, and complement activation. Blockade of individual pathways generally does not prevent allograft rejection, and long-term allograft survival is achieved only after simultaneous blockade of several of them. In this review, we explore each of these pathways and discuss the experimental evidence highlighting their roles in allograft rejection.     

CXC趋化因子受体6在小鼠心脏移植排斥反应中的表达及意义

目的 研究CXC趋化因子受体6(CXCR6)在同种异体小鼠心脏移植中的表达及CXC趋化因子配体16(CXCL16)与CXCR6相互作用对移植物存活时间的影响.方法 以野生型Balb/c小鼠(H-2d)为供者(同种移植组),或以野生型C57BL/6小鼠(H-2b)为供者(同系移植组),以野生型C57BL/6小鼠为受者分别行小鼠腹腔异位心脏移植.测定同系和同种移植组小鼠移植心脏CXCR6mRNA的表达,并测定受者脾脏CD8+T淋巴细胞CXCR6的表达.另制作小鼠同种异位心脏移植模型(Balb/c小鼠为供者,C57BL/6小鼠为受者),将其分为实验组和对照组,实验组受者移植当天至发生排斥反应时腹腔注射抗CXCL16抗体,对照组受者同期注射对照抗体.记录两组移植心脏存活时间.进行CD8+T淋巴细胞的细胞毒试验,即用Balb/c小鼠脾细胞免疫C57BL/6小鼠后,获取C57BL/6小鼠脾脏CD8+T淋巴细胞,将Balb/c小鼠脾细胞与C57BL/6小鼠CD8+T淋巴细胞混合培养,分别加入抗CXCL16抗体、小鼠IgG(对照抗体)和抗CD40L抗体.结果 同种移植组移植心脏中CXCR6 mRNA的表达以及脾脏CD8+T淋巴细胞上CXCR6的表达均高于同系移植组和正常对照组.抗CXCL16抗体对CD8+T淋巴细胞的细胞毒活性无影响.与对照组相比较,实验组小鼠移植心脏存活时间并未明显延长.结论 小鼠心脏移植排斥反应中CD8+T淋巴细胞CXCR6的表达上升,阻断CXCL16/CXCR6相互作用并不能延长移植心脏的存活时间.     

Inhibition of chronic rejection and development of tolerogenic T cells after ICOS-ICOSL and CD40-CD40L co-stimulation blockade

BACKGROUND: Blockade of the CD40-CD40L pathway results in long-term allograft survival but does not prevent chronic rejection. ICOS-ICOSL are members of the CD28-B7 family that play an important role in T-cell activation. METHODS: The authors analyzed the effect of single or combined treatment with an anti-ICOS monoclonal antibody and the fusion molecule CD40 immunoglobulin (Ig) on acute and chronic rejection of heart allografts in rats. RESULTS: Treatment with anti-ICOS resulted in a modest but significant prolongation of allograft survival. Treatment with CD40Ig resulted in long-term graft survival but the cardiac grafts developed chronic rejection lesions. Combined CD40Ig+anti-ICOS treatment led to indefinite graft survival in all recipients and a significant decrease of chronic rejection lesions compared with CD40Ig alone. Importantly, four of the seven CD40Ig+anti-ICOS-treated recipients showed a complete absence of chronic rejection lesions, whereas all of the CD40Ig-treated recipients showed chronic rejection. The CD40Ig+anti-ICOS group also showed significant decreased graft infiltration, decreased antidonor cytotoxic T-lymphocyte activity, and decreased alloantibodies compared with the CD40Ig-treated group. Adoptive transfer of splenocytes indefinitely prolonged allograft survival, whereas those depleted of T cells did not, suggesting the development of T-regulatory mechanisms. CONCLUSIONS. These data indicate that the chronic rejection mechanisms that are CD40-CD40L independent are ICOS-ICOSL dependent. These results were obtained with conservation of cognate immune responses and development of tolerogenic T cells.     

CXC趋化因子受体6在小鼠心脏移植排斥反应中的表达及意义

目的 研究CXC趋化因子受体6(CXCR6)在同种异体小鼠心脏移植中的表达及CXC趋化因子配体16(CXCL16)与CXCR6相互作用对移植物存活时间的影响.方法 以野生型Balb/c小鼠(H-2d)为供者(同种移植组),或以野生型C57BL/6小鼠(H-2b)为供者(同系移植组),以野生型C57BL/6小鼠为受者分别行小鼠腹腔异位心脏移植.测定同系和同种移植组小鼠移植心脏CXCR6mRNA的表达,并测定受者脾脏CD8+T淋巴细胞CXCR6的表达.另制作小鼠同种异位心脏移植模型(Balb/c小鼠为供者,C57BL/6小鼠为受者),将其分为实验组和对照组,实验组受者移植当天至发生排斥反应时腹腔注射抗CXCL16抗体,对照组受者同期注射对照抗体.记录两组移植心脏存活时间.进行CD8+T淋巴细胞的细胞毒试验,即用Balb/c小鼠脾细胞免疫C57BL/6小鼠后,获取C57BL/6小鼠脾脏CD8+T淋巴细胞,将Balb/c小鼠脾细胞与C57BL/6小鼠CD8+T淋巴细胞混合培养,分别加入抗CXCL16抗体、小鼠IgG(对照抗体)和抗CD40L抗体.结果 同种移植组移植心脏中CXCR6 mRNA的表达以及脾脏CD8+T淋巴细胞上CXCR6的表达均高于同系移植组和正常对照组.抗CXCL16抗体对CD8+T淋巴细胞的细胞毒活性无影响.与对照组相比较,实验组小鼠移植心脏存活时间并未明显延长.结论 小鼠心脏移植排斥反应中CD8+T淋巴细胞CXCR6的表达上升,阻断CXCL16/CXCR6相互作用并不能延长移植心脏的存活时间.

Abstract：

Objective To investigate the expression of CXCR6 in allograft rejection and effect of CXCL16/CXCR6 interaction on allograft survival Methods Intra-abdominal heterotopic heart transplantation was performed using wild type (WT) Balb/c mice (H-2d) (allogeneic) as donors or WT C57BL/6 mice (B6, H-2b) (syngeneic) as donors, and using WT B6 mice as recipients. The intragraft expression of CXCR6 and expression of CXCR6 in CD8+ T cells of the spleens from syngeneic and allogeneic recipients were examined. The allogeneic recipients were further divided into the experimental group (n = 5) and control group (n = 6) randomly. The experiment group and control group were injected with anti-CXCL16 mAb or control mAb respectively until rejection occurred. The cardiac allograft survival in experimental group and control group was evaluated. Results Rejected allografts showed higher expression of CXCR6 than syngeneic cardiac grafts. More importantly,expression of CXCR6 in CD8+ T cells was also up-regulated by allograft rejection. However, injection of anti-CXCL16 mAb could not inhibit cytotoxic activity of CD8+ T cells. Moreover, experimental group could not prolong the cardiac graft survival time as compared with control group. Conclusion Expression of CXCR6 in CD8+ T cells is up-regulated in allograft rejection.     

CXC趋化因子受体6在小鼠心脏移植排斥反应中的表达及意义

目的 研究CXC趋化因子受体6(CXCR6)在同种异体小鼠心脏移植中的表达及CXC趋化因子配体16(CXCL16)与CXCR6相互作用对移植物存活时间的影响.方法 以野生型Balb/c小鼠(H-2d)为供者(同种移植组),或以野生型C57BL/6小鼠(H-2b)为供者(同系移植组),以野生型C57BL/6小鼠为受者分别行小鼠腹腔异位心脏移植.测定同系和同种移植组小鼠移植心脏CXCR6mRNA的表达,并测定受者脾脏CD8+T淋巴细胞CXCR6的表达.另制作小鼠同种异位心脏移植模型(Balb/c小鼠为供者,C57BL/6小鼠为受者),将其分为实验组和对照组,实验组受者移植当天至发生排斥反应时腹腔注射抗CXCL16抗体,对照组受者同期注射对照抗体.记录两组移植心脏存活时间.进行CD8+T淋巴细胞的细胞毒试验,即用Balb/c小鼠脾细胞免疫C57BL/6小鼠后,获取C57BL/6小鼠脾脏CD8+T淋巴细胞,将Balb/c小鼠脾细胞与C57BL/6小鼠CD8+T淋巴细胞混合培养,分别加入抗CXCL16抗体、小鼠IgG(对照抗体)和抗CD40L抗体.结果 同种移植组移植心脏中CXCR6 mRNA的表达以及脾脏CD8+T淋巴细胞上CXCR6的表达均高于同系移植组和正常对照组.抗CXCL16抗体对CD8+T淋巴细胞的细胞毒活性无影响.与对照组相比较,实验组小鼠移植心脏存活时间并未明显延长.结论 小鼠心脏移植排斥反应中CD8+T淋巴细胞CXCR6的表达上升,阻断CXCL16/CXCR6相互作用并不能延长移植心脏的存活时间.     

CXC趋化因子受体6在小鼠心脏移植排斥反应中的表达及意义

目的 研究CXC趋化因子受体6(CXCR6)在同种异体小鼠心脏移植中的表达及CXC趋化因子配体16(CXCL16)与CXCR6相互作用对移植物存活时间的影响.方法 以野生型Balb/c小鼠(H-2d)为供者(同种移植组),或以野生型C57BL/6小鼠(H-2b)为供者(同系移植组),以野生型C57BL/6小鼠为受者分别行小鼠腹腔异位心脏移植.测定同系和同种移植组小鼠移植心脏CXCR6mRNA的表达,并测定受者脾脏CD8+T淋巴细胞CXCR6的表达.另制作小鼠同种异位心脏移植模型(Balb/c小鼠为供者,C57BL/6小鼠为受者),将其分为实验组和对照组,实验组受者移植当天至发生排斥反应时腹腔注射抗CXCL16抗体,对照组受者同期注射对照抗体.记录两组移植心脏存活时间.进行CD8+T淋巴细胞的细胞毒试验,即用Balb/c小鼠脾细胞免疫C57BL/6小鼠后,获取C57BL/6小鼠脾脏CD8+T淋巴细胞,将Balb/c小鼠脾细胞与C57BL/6小鼠CD8+T淋巴细胞混合培养,分别加入抗CXCL16抗体、小鼠IgG(对照抗体)和抗CD40L抗体.结果 同种移植组移植心脏中CXCR6 mRNA的表达以及脾脏CD8+T淋巴细胞上CXCR6的表达均高于同系移植组和正常对照组.抗CXCL16抗体对CD8+T淋巴细胞的细胞毒活性无影响.与对照组相比较,实验组小鼠移植心脏存活时间并未明显延长.结论 小鼠心脏移植排斥反应中CD8+T淋巴细胞CXCR6的表达上升,阻断CXCL16/CXCR6相互作用并不能延长移植心脏的存活时间.