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![A) RIB5/2 therapy given alone resulted in seven out of nine rats in permanent graft survival (>100 d) while FTY720 therapy prolonged graft survival for 1 day [mean survival time (MST) 7.0 d, n = 7] compared with untreated controls (MST 6.2 d, n = 5). The group receiving combination therapy survived for 45.2 d only (n = 5). (B) Serum creatinine values were significantly increased from day 21 after combination therapy FTY720 + RIB5/2 (n = 5) in comparison with controls receiving 10 mg/kg of RIB5/2 therapy (n = 9) (U-test, p < 0.05).](publication/8559578/figure/fig6/AS:271734351855631@1441797926697/A-RIB5-2-therapy-given-alone-resulted-in-seven-out-of-nine-rats-in-permanent-graft.png)
A) RIB5/2 therapy given alone resulted in seven out of nine rats in permanent graft survival (>100 d) while FTY720 therapy prolonged graft survival for 1 day [mean survival time (MST) 7.0 d, n = 7] compared with untreated controls (MST 6.2 d, n = 5). The group receiving combination therapy survived for 45.2 d only (n = 5). (B) Serum creatinine values were significantly increased from day 21 after combination therapy FTY720 + RIB5/2 (n = 5) in comparison with controls receiving 10 mg/kg of RIB5/2 therapy (n = 9) (U-test, p < 0.05).
Source publication
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...
Citations
... Decreased receptor expression results in impaired lymphocyte egress from the thymus, Peyer's Patches, and pLNs leading to LN sequestration, lymphopenia and reduced lymphocyte recirculation to inflammatory sites, including allografts. 150 Thus, fingolimod renders the LN a repository of effector cells and prevents effector function in target organs. When used in conjunction with additional immunosuppressive agents, including calcineurin and proliferation inhibitors, there is synergism for preventing graft rejection. ...
Lymph nodes (LNs) are at the cross roads of immunity and tolerance. These tissues are compartmentalized into specialized niche areas by lymph node stromal cells (LN SCs). LN SCs shape the LN microenvironment and guide immunological cells into different zones through establishment of a CCL19 and CCL21 gradient. Following local immunological cues, LN SCs modulate activity to support immune cell priming, activation, and fate. This review will present our current understanding of LN SC subsets roles in regulating T cell tolerance. Three major types of LN SC subsets, namely fibroblastic reticular cells, lymphatic endothelial cells, and blood endothelial cells, are discussed. These subsets serve as scaffolds to support and regulate T cell homeostasis. They contribute to tolerance by presenting peripheral tissue antigens to both CD4 and CD8 T cells. The role of LN SCs in regulating T cell migration and tolerance induction is discussed. Looking forward, recent advances in bioengineered materials and approaches to leverage LN SCs to induce T cell tolerance are highlighted, as are current clinical practices that allow for manipulation of the LN microenvironment to induce tolerance. Increased understanding of LN architecture, how different LN SCs integrate immunological cues and shape immune responses, and approaches to induce T cell tolerance will help further combat autoimmune diseases and graft rejection.
... The latter is also resistant to breaking by individual interventions, such as increasing the numbers of naïve alloreactive T cells, or allowing T cells to homeostatically proliferate, or providing additional alloantigen and ischemia-reperfusion inflammation via giving a new transplant, or depleting Tregs [14][15][16]. Additionally, Schroeder et al. showed that established tolerance induced with anti-CD4 alone was resistant to breakage with FTY720, an intervention that is capable of preventing the induction of tolerance [17]. This observation suggests that recirculation of new immune cells to the graft is not necessary for maintenance of tolerance, but is necessary for its induction. ...
Purpose of Review
It has long been considered that tolerance in a transplant recipient is a binary all-or-none state: either the graft is accepted without immunosuppression identifying the recipient as tolerant, or the recipient rejects the graft and is not tolerant. This tolerance paradigm, however, does not accurately reflect data emerging from animal models and patients and requires revision.
Recent Findings
It is becoming appreciated that there may be different gradations in the quality of transplantation tolerance based on underlying cellular mechanisms of immunological tolerance, and that individuals may enhance the robustness of their state of transplant tolerance by strengthening or combining different cellular mechanisms. Furthermore, evidence suggests that even if tolerance is lost, the loss may be only temporary, and in some circumstances, tolerance can be restored.
Summary
Shifting our focus from an all-or-nothing tolerance paradigm to one with many shades may help us better understand how tolerance operates, and how this state may be tracked and enhanced for better patient outcomes.
... In addition to infections, manipulations that increase the na€ ıve or memory T cell precursor frequency, or those that directly target mechanisms of peripheral T cell tolerance (i.e. preventing apoptosis, depleting/inhibiting regulatory cells, or blocking signals through the negative regulatory PD-1/PD-L1 [programmed cell death protein 1/programmed death ligand-1] pathway) all result in the inability to induce tolerance (7)(8)(9)(10)(11)(12)(13)(14)(15)(16). ...
Solid organ transplantation tolerance can be achieved following select transient immunosuppressive regimens that result in long-lasting restraint of alloimmunity without affecting responses to other antigens. Transplantation tolerance has been observed in animal models following costimulation or coreceptor blockade therapies, and in a subset of patients through induction protocols that include donor bone marrow transplantation, or following withdrawal of immunosuppression. Previous data from our lab and others have shown that proinflammatory interventions that successfully prevent the induction of transplantation tolerance in mice often fail to break tolerance once it has been stably established. This suggests that established tolerance acquires resilience to proinflammatory insults, and prompted us to investigate the mechanisms that maintain a stable state of robust tolerance. Our results demonstrate that only a triple intervention of depleting CD25+ regulatory T cells (Tregs), blocking programmed death ligand-1 (PD-L1) signals, and transferring low numbers of alloreactive T cells was sufficient to break established tolerance. We infer from these observations that Tregs and PD-1/PD-L1 signals cooperate to preserve a low alloreactive T cell frequency to maintain tolerance. Thus, therapeutic protocols designed to induce multiple parallel mechanisms of peripheral tolerance may be necessary to achieve robust transplantation tolerance capable of maintaining one allograft for life in the clinic. © 2016 The American Society of Transplantation and the American Society of Transplant Surgeons.
... It has been reported that the use of FTY720 in combination with RIB 5/2 prevents tolerance induction (45). Therefore, the selection of drugs for synergistic treatment with tolerance induction protocols appears to be a challenge. ...
Ischemia/reperfusion injury leads to activation of graft endothelial cells (EC), boosting antigraft immunity and impeding tolerance induction. We hypothesized that the complement inhibitor and EC-protectant dextran sulfate (DXS, MW 5000) facilitates long-term graft survival induced by non-depleting anti-CD4 mAb (RIB 5/2). Hearts from DA donor rats were heterotopically transplanted into Lewis recipients treated with RIB 5/2 (20 mg/kg, days-1,0,1,2,3; i.p.) with or without DXS (grafts perfused with 25 mg, recipients treated i.v. with 25 mg/kg on days 1,3 and 12.5 mg/kg on days 5,7,9,11,13,15). Cold graft ischemia time was 20 min or 12 h. Median survival time (MST) was comparable between RIB 5/2 and RIB 5/2+DXS-treated recipients in the 20-min group with >175-day graft survival. In the 12-h group RIB 5/2 only led to chronic rejection (MST = 49.5 days) with elevated alloantibody response, whereas RIB 5/2+DXS induced long-term survival (MST >100 days, p < 0.05) with upregulation of genes related to transplantation tolerance. Analysis of the 12-h group treated with RIB 5/2+DXS at 1-day posttransplantation revealed reduced EC activation, complement deposition and inflammatory cell infiltration. In summary, DXS attenuates I/R-induced acute graft injury and facilitates long-term survival in this clinically relevant transplant model.
... Depletion of CD4 + cells, using RIB-5/2, prolonged allogeneic kidney survival in a DA to LEW model [35, 36], implying that interference with the immune response in a fully mismatched model can prolong graft survival. ...
... Treg have been shown to induce tolerance, but the role of Th17 cells in transplantation settings is still unknown. Depletion of CD4 + cells, using RIB-5/2, prolonged allogeneic kidney survival in a DA to LEW model [35,36], implying that interference with the immune response in a fully mismatched model can prolong graft survival. ...
The CD40-CD40L interaction plays a critical role in cell-mediated immune responses. Blocking this interaction has been shown to be beneficial in the treatment of various diseases studied in murine models. Although rats are widely used to test therapeutic strategies in several disease models, a monoclonal antibody (mAb) to block the CD40-CD40L interaction in rats is not broadly available. In the present study we generated Armenian hamster fibroblasts expressing rat CD40L and used these to generate a novel anti-rat CD40L mAb (AS1). In vitro studies showed that AS1 was able to block CD40L-induced DC maturation and B cell proliferation. Most importantly, in vivo, AS1 inhibited B cell responses in a dose-dependent fashion, as measured by the production of OVA specific antibodies after subcutaneous immunization with OVA. AS1 was shown to be a powerful tool to modulate Ag presentation in vitro and in vivo. Elucidating the effect of AS1 in various rat models for human diseases will provide more insight into blocking the CD40-CD40L interaction as a therapeutic strategy to prevent human diseases.
Mitsubishi Pharma Corp and Novartis AG are developing fingolimod, an orally active immunosuppressant affecting lymphocyte re-circulation, for the potential prevention of transplant rejection and the treatment of autoimmune diseases, including multiple sclerosis. Fingolimod is a synthetic sphingosine analog that becomes phosphorylated in vivo and acts as a sphingosine-1-phosphate receptor agonist.
The chemokine receptor CCR7 plays a pivotal role in the homing of naïve T cells and regulatory T cells to secondary lymphoid organs and the migration of dendritic cells into afferent lymphatic vessels. Antigen presentation, T cell recruitment, and expansion of regulatory cells are crucial events in establishing and controlling chronic allograft dysfunction. In this study, we report an important role for chemokine receptor CCR7 in the development of transplant arteriosclerosis.
Fully major histocompatibility complex-mismatched CBA (H2) donor aortas were transplanted into BALB/c-CCR7 (H2), BALB/c-CCR7 (H2), or BALB/c-CCR7 (H2) recipients. Grafts were analyzed by histology, morphometry, and immunofluorescence on day 30 after transplantation. Intragraft cytokine mRNA production was analyzed by realtime polymerase chain reaction on day 14 after transplantation.
After implanting fully major histocompatibility complex-mismatched donor aortas into CCR7-deficient recipients, transplant arteriosclerosis was significantly elevated. CD4 depletion resulted in a reduction of intima proliferation in CCR7 recipients whereas CD8 depletion had no effect. Analysis of aortic grafts from CCR7 recipients revealed high numbers of infiltrating CD4, F4/80, and CD205 cells. Furthermore, intragraft cytokine production showed higher levels of interleukin-4, interleukin-12, and eotaxin mRNA expression, whereas significantly lower Foxp3 mRNA expression was observed in CCR7 recipients.
These data suggest that although alloantigen presentation in secondary lymphoid organs is hampered in CCR7-deficient recipients, this process may take place within the allograft itself, leading to increased formation of transplant arteriosclerosis. The decrease in Foxp3 expression despite increased in CD4 T cell infiltration indicates a reduction in T regulatory cells possibly influencing the intensity of the graft rejection.
T cell migration and trafficking are regulated by the well defined cellular processes of rolling, activation, tight adhesion, arrest and diapedesis. These processes are, in turn, controlled by molecular events involving integrins, selectins, chemokines and chemokine receptors. Recent studies have shown that sphingosine 1-phosphate receptors and their ligands are also important molecular modulators of migration and trafficking. Many of these molecules are appropriate targets for preventing allograft rejection or for achieving tolerance. Studies of migration and trafficking have also shown that the anatomic choreography of alloantigen presentation and T cell encounter with alloantigen and immunosuppression, are over-riding determinants of T cell priming versus tolerization.
Mitsubishi Pharma Corp and Novartis AG are developing fingolimod, an orally active immunosuppressant affecting lymphocyte re-circulation, for the potential prevention of transplant rejection and the treatment of autoimmune diseases, including multiple sclerosis. Fingolimodis a synthetic sphingosine analog that becomes phosphorylated in vivo and acts as a sphingosine-1-phosphate receptor agonist.
