The clinical success of new treatment strategies aiming on inducing permanent graft acceptance will rely on the ability to determine whether specific unresponsiveness to donor alloantigens has ...developed and for how long it is maintained. To identify markers for such posttransplant monitoring, genes differentially expressed by graft infiltrating leukocytes during tolerance induction or rejection after kidney transplantation in rats were compared. A subsequently performed full kinetic analysis in two different transplant models, kidney and heart, in two species, rat and mouse identified two markers (TOAG‐1, α‐1,2‐mannosidase) with high specificity and reproducibility, which are highly expressed during induction and maintenance of acceptance, and downregulated during rejection. Expression level of these markers showed a strong positive correlation with graft function. In addition, expression of both genes was downregulated in the peripheral blood and the graft prior to rejection, suggesting that these markers may be useful for monitoring in clinical transplantation where peripheral blood is the most easily accessible patient sample. Interestingly, downregulation of TOAG‐1 and α‐1,2‐mannosidase expression occurred in graft infiltrating cells and expression of both genes was also downregulated after T‐cell activation in vitro.
Gene expression profiling of intragraft and peripheral blood samples in experimental transplant and autoimmune models identified two genes whose expression is associated with tolerance.
Recent data suggest that donor‐specific memory T cells (Tmem) are an independent risk factor for rejection and poor graft function in patients and a major challenge for immunosuppression minimizing ...strategies. Many tolerance induction protocols successfully proven in small animal models e.g. costimulatory blockade, T cell depletion failed in patients. Consequently, there is a need for more predictive transplant models to evaluate novel promising strategies, such as adoptive transfer of regulatory T cells (Treg).
We established a clinically more relevant, life‐supporting rat kidney transplant model using a high responder (DA to LEW) recipients that received donor‐specific CD4+/ 8+ GFP+ Tmem before transplantation to achieve similar pre‐transplant frequencies of donor‐specific Tmem as seen in many patients. T cell depletion alone induced long‐term graft survival in naïve recipients but could not prevent acute rejection in Tmem+ rats, like in patients. Only if T cell depletion was combined with permanent CNI‐treatment, the intragraft inflammation, and acute/chronic allograft rejection could be controlled long‐term. Remarkably, combining 10 days CNI treatment and adoptive transfer of Tregs (day 3) but not Treg alone also induced long‐term graft survival and an intragraft tolerance profile (e.g. high TOAG‐1) in Tmem+ rats. Our model allows evaluation of novel therapies under clinically relevant conditions.
Adoptive transfer of green fluorescent protein expressing alloreactive memory CD4+ and CD8+ T cells 7 or even 100 days prior to kidney transplantation elicits an acute rejection refractory to T cell depletion, which can only be prevented by permanent cyclosporine A therapy or a combined treatment of cyclosporine A and regulatory T cells.
To ensure safety tolerance induction protocols are accompanied by conventional immunosuppressive drugs (IS). But IS such as calcineurin inhibitors (CNI), for example, cyclosporin A (CsA), can ...interfere with tolerance induction. We investigated the effect of an additional transient CsA treatment on anti‐CD4mAb‐induced tolerance induction upon rat kidney transplantation. Additional CsA treatment induced deteriorated graft function, resulting in chronic rejection characterized by glomerulosclerosis, interstitial fibrosis, tubular atrophy and vascular changes. Microarray analysis revealed enhanced intragraft expression of the B cell attracting chemokine CXCL13 early during CsA treatment. Increase in CXCL13 expression is accompanied by enhanced B cell infiltration with local and systemic IgG production and C3d deposition as early as 5 days upon CsA withdrawal. Adding different CNIs to cultures of primary mesangial cells isolated from glomeruli resulted in a concentration‐dependent increase in CXCL13 transcription. CsA in synergy with TNF‐α can enhance the B cell attracting and activating potential of mesangial cells. Transient B cell depletion or transfer of splenocytes from tolerant recipients 3 weeks after transplantation could rescue tolerance induction and did inhibit intragraft B cell accumulation, alloantibody production and ameliorate chronic rejection.
Transient coapplication of cyclosporine A abrogates CD4‐specific monoclonal antibody‐mediated transplant tolerance by inducing intragraft CXCL13 expression leading to B cell attraction, alloantibody production and complement‐mediated tissue destruction.
FTY720 is highly effective in various models of transplantation and autoimmunity. In order to find drugs that act synergistically with a tolerance‐inducing nondepleting anti‐CD4 mAb we studied this ...combination in a strong DA to LEW kidney transplantation model. Rats were treated with 0.3 mg/kg of FTY720 for 14 days and anti‐CD4 mAb RIB5/2, alone or in combination. After kidney transplantation serum creatinine and blood lymphocyte counts were monitored. Immunohistology, ELISPOT and TaqMan™‐PCR analysis of biopsies were performed.
Short‐term application of RIB5/2 but not FTY720 induced long‐term survival of kidney transplants. Moreover, the combination of FTY720 + RIB5/2 prevented tolerance induction. In the combination group serum creatinine levels increased 1 week after cessation of therapy and all rats died from uremia within 72 days. Intragraft immunohistology, ELISPOT and real‐time RT‐PCR analysis at day 21 demonstrated an enhanced T‐cell infiltration and activation but a diminished up‐regulation of protective genes in the grafts from recipients receiving the combination therapy. In contrast, delayed application of FTY720 to RIB5/2‐treated rats did not interact with RIB5/2‐induced tolerance.
In summary, FTY720 is powerful in preventing intragraft infiltration by naive T cells but this might also affect the early development of graft‐protecting regulatory T cells and tolerance induction.
Recently, we demonstrated the capacity of allo‐specific gene‐engineered T lymphocytes as transport vehicle for therapeutic transgenes into allografts. In this study, the influence of viral IL‐10 as ...therapeutic transgene was addressed. Lewis rat T‐cell lines specific for DA rat alloantigens were engineered to express vIL‐10 by using a retroviral gene expression system. Like T regulatory 1 cells, vIL‐10 transgenic T lymphocytes express the phenotype CD4+25+ and secrete, in addition to vIL‐10, rat IL‐10 and IFN‐γ but no IL‐4. First, the capacity of vIL‐10 transgenic T‐cell lines to modulate alloantigen‐specific immune responses was evaluated in vitro. In comparison to control MLR with no transgenic cells or equal numbers of control TEGFP‐lymphocytes, the proliferation as well as production of IFN‐γ by naive responder cells were significantly diminished. Despite this regulatory capacity in vitro, TvIL‐10‐lymphocytes were not able, either alone or in combination with suboptimal doses of Cyclosporine A, to prolong the survival of either DA rat cardiac or renal allografts in Lewis rat recipients. These data demonstrate that intra‐graft IL‐10 over‐expression is not sufficient to prolong allograft survival in a high‐responder strain combination and that the regulatory capacity of T cells in vitro does not predict their in vivo efficiency.
The Management of Scientists Passeron, J. C.; Mendelsohn, E.; Roe, A. ...
Revue française de sociologie,
04/1966, Letnik:
7, Številka:
2
Journal Article
Demokratie-Dialog 14-24 Forschungs- und Dokumentationsstelle zur Analyse politischer und religiöser Extremismen in Niedersachsen (FoDEx); Fitzpatrick, Sally A; Franzmann, Simon T ...
2024
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