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Tracking of TCR-Transgenic T Cells Reveals That Multiple Mechanisms Maintain Cardiac Transplant Tolerance in Mice.

ABSTRACT: 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.

SUBMITTER: Miller ML

PROVIDER: S-EPMC6241514 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Tracking of TCR-Transgenic T Cells Reveals That Multiple Mechanisms Maintain Cardiac Transplant Tolerance in Mice.

Miller M L ML Daniels M D MD Wang T T Wang Y Y Xu J J Yin D D Chong A S AS Alegre M-L ML

American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons 20160505 10

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 ...[more]

PMID: 27091509

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Project description:BackgroundEndotoxin tolerance (ET) is a protective mechanism in the process of sepsis, septic shock, and their sequelae including uncontrolled inflammation. Accumulating evidence has shown that peripheral T cells contribute to the induction of ET. However, what and how T-cell development contributes to ET inductions remain unclear.MethodsMice were intraperitoneally injected with LPS at a concentration of 5 mg/kg to establish an LPS tolerance model and were divided into two groups: a group examined 72 h after LPS injection (72-h group) and a group examined 8 days after LPS injection (8-day group). Injection of PBS was used as a control. We performed high-throughput sequencing to analyze the characteristics and changes of CD4+SP TCRβ CDR3 repertoires with respect to V direct to J rearrangement during the ET induction. Moreover, the proportion and proliferation, as well as surface molecules such as CD80 and CD86, of F4/80+ macrophages were analyzed using FCM. Furthermore, ACT assay was designed and administered by the tail vein into murine LPS-induced mouse model to evaluate the role of F4/80+ macrophages on the development of CD4+SP thymocytes in ET condition.ResultsWe found that the frequency and characteristics of the TCRβ chain CDR3 changed obviously under condition of ET, indicating the occurrence of TCR rearrangement and thymocyte diversification. Moreover, the absolute numbers of F4/80+ macrophages, but not other APCs, were increased in thymic medulla at 72-h group, accompanied by the elevated function-related molecules of F4/80+ macrophages. Furthermore, adoptively transferred OVA332-339 peptide-loaded macrophages into Rag-1-/- mice induced the clone deletion of OVA-specific CD4+SP, thereby ameliorating the pathology in lung tissue in LPS challenge.ConclusionsThese data reveal that the frequency and characteristics of the TCRβ chain CDR3 undergo dynamic programming under conditions of LPS tolerance. Furthermore, the peripheral macrophages may be a key factor which carry peripheral antigen to thymic medulla and affect the negative selection of T-cell population, thereby contributing to the formation of ET. These results suggest that the clone selection in thymus in ET may confer protection against microbial sepsis.

Project description:Genetically engineered virus-specific T cells (VSTs) are a platform for adoptive cell therapy after allogeneic hematopoietic stem cell transplantation. However, redirection to a tumor-associated antigen by the introduction of a transgenic T-cell receptor (TCR) reduces anti-viral activity, thereby impeding the possibility of preventing or treating two distinct complications-malignant relapse and viral infection-with a single cell therapy product. Availability of CD8αβ co-receptor molecules can significantly impact class I restricted T-cell activation, and thus, we interrogated whether transgenic CD8αβ improves anti-viral activity mediated by native VSTs with or without a co-expressed transgenic TCR (TCR8). Our existing clinical VST manufacturing platform was adapted and validated to engineer TCR+ or TCR8+ VSTs targeting cytomegalovirus and Epstein-Barr virus. Simultaneous anti-viral and anti-tumor function of engineered VSTs was assessed in vitro and in vivo. We used pentamer staining, interferon (IFN)-γ enzyme-linked immunospot (ELISpot), intracellular cytokine staining (ICS), cytotoxicity assays, co-cultures, and cytokine secretion assays for the in vitro characterization. The in vivo anti-tumor function was assessed in a leukemia xenograft mouse model. Both transgenic CD8αβ alone and TCR8 had significant impact on the anti-viral function of engineered VSTs, and TCR8+ VSTs had comparable anti-viral activity as non-engineered VSTs as determined by IFN-γ ELISpot, ICS and cytotoxicity assays. TCR8-engineered VSTs had improved anti-tumor function and greater effector cytokine production in vitro, as well as enhanced anti-tumor function against leukemia xenografts in mice. Incorporation of transgenic CD8αβ into vectors for TCR-targetable antigens preserves anti-viral activity of TCR transgenic VSTs while simultaneously supporting tumor-directed activity mediated by a transgenic TCR. Our approach may provide clinical benefit in preventing and treating viral infections and malignant relapse post-transplant.

Dataset Information

Tracking of TCR-Transgenic T Cells Reveals That Multiple Mechanisms Maintain Cardiac Transplant Tolerance in Mice.

Publications

Tracking of TCR-Transgenic T Cells Reveals That Multiple Mechanisms Maintain Cardiac Transplant Tolerance in Mice.

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