Project description:Mouse monocytes exposed to M-CSF and IFN-M-NM-3 were driven to a suppressor phenotype over a seven day culture period. The resulting regulatory macrophages (M regs) expressed markers distinguishing them from M0-, M1-, and M2-polarised macrophages and monocyte-derived DCs. M regs completely suppressed polyclonal T cell proliferation through an inducibile nitric oxide synthase (iNOS)-dependent mechanism. Additionally, M regs were found to eliminate cocultured T cells in an allospecific fashion. In a heterotopic heart transplant model, a single intravenous administration of 5x10^6 donor-strain M regs prior to transplantation significantly prolonged allograft survival in fully immunocompetent recipients using both the stringent C3H-to-BALB/c and C57BL/6-to-BALB/c strain combinations; this graft-protective effect was alloantigen-specific. M regs from Nos2-deficient mice did not prolong allograft survival, proving that M reg function in vivo is iNOS-mediated and dependent on living cells. Co-treatment with 1 mg/kg/day rapamycin for 10 days post-transplant markedly enhanced the effect of M regs. In untransplanted C57BL/6 recipients, M regs of BALB/c origin were detectable for up to 2 weeks post-infusion. It is concluded that mouse M regs represent a novel, phenotypically distinct subset of tolerogenic macrophages, which resemble human M regs in their derivation, phenotype and in vitro functions. The dataset comprises 36 samples divided into twelve sample groups each representing a certain monocyte/macrophage subtype
Project description:Mouse monocytes exposed to M-CSF and IFN-γ were driven to a suppressor phenotype over a seven day culture period. The resulting regulatory macrophages (M regs) expressed markers distinguishing them from M0-, M1-, and M2-polarised macrophages and monocyte-derived DCs. M regs completely suppressed polyclonal T cell proliferation through an inducibile nitric oxide synthase (iNOS)-dependent mechanism. Additionally, M regs were found to eliminate cocultured T cells in an allospecific fashion. In a heterotopic heart transplant model, a single intravenous administration of 5x10^6 donor-strain M regs prior to transplantation significantly prolonged allograft survival in fully immunocompetent recipients using both the stringent C3H-to-BALB/c and C57BL/6-to-BALB/c strain combinations; this graft-protective effect was alloantigen-specific. M regs from Nos2-deficient mice did not prolong allograft survival, proving that M reg function in vivo is iNOS-mediated and dependent on living cells. Co-treatment with 1 mg/kg/day rapamycin for 10 days post-transplant markedly enhanced the effect of M regs. In untransplanted C57BL/6 recipients, M regs of BALB/c origin were detectable for up to 2 weeks post-infusion. It is concluded that mouse M regs represent a novel, phenotypically distinct subset of tolerogenic macrophages, which resemble human M regs in their derivation, phenotype and in vitro functions.
Project description:Transplantation is the preferred treatment for most patients with end-stage organ disease, but long-term outcomes are hindered by immunosuppressive drug toxicity and immune-mediated injury. Developing therapies that promote immune tolerance while minimizing systemic immunosuppression is essential to improve graft health and survival. Regulatory T cell (Treg)-based therapies offer promise for inducing antigen-specific transplant tolerance, with recombinant IL-2 analogs emerging as potentially effective tools to selectively expand Tregs while minimizing adverse effects. mIL-2 therapy combined with co-stimulation blockade significantly prolonged allograft survival in an antigen-specific manner without adverse events. The immunomodulatory effects of mIL-2 persisted even after treatment cessation at 60 days after transplantation, with sustained graft function and preservation of histopathological integrity. Treatment with mIL-2 increased graft-infiltrating Tregs and decreased effector T cell activation. Donor-specific antibody production was reduced in mIL-2-treated recipients, which correlated with an enhanced follicular regulatory T-cell proportion. These findings were consistent across fully mismatched kidney and haplo-mismatched heart transplant models. Transcriptional profiling revealed the expansion of an ST2-positive, tissue-resident Treg population critical for long-term graft survival. Accordingly, the mIL-2-induced Treg suppression was abrogated in Treg-specific ST2 knockout graft recipients.
Project description:Complications associated with immunosuppression, specifically nephrotoxicity and infection risk, significantly affect graft and patient survival after kidney transplantation. We previously showed that tolerance could be induced and full donor chimerism, as well as immunosuppression withdrawal, was obtained in highly mismatched allograft recipients using a bioengineered stem cell product (FCRx).
Project description:The innate immune system plays an essential role in regulating the immune responses to kidney transplantation, but the mechanisms through which innate immune cells influence long-term graft survival are unclear. The current study highlights the vital role of trained immunity in kidney allograft survival. Trained immunity describes the epigenetic and metabolic changes that innate immune cells undergo following an initial stimulus, allowing them have a stronger inflammatory response to subsequent stimuli. We stimulated healthy peripheral blood mononuclear cells with pretransplant and posttransplant serum of kidney transplant patients and immunosuppressive drugs in an in vitro trained immunity assay and measured tumor necrosis factor and interleukin 6 cytokine levels in the supernatant as a readout for trained immunity. We show that the serum of kidney transplant recipients collected 1 week after transplantation can suppress trained immunity. Importantly, we found that kidney transplant recipients whose serum most strongly suppressed trained immunity rarely experienced graft loss. This suppressive effect of posttransplant serum is likely mediated by previously unreported effects of immunosuppressive drugs. Our findings provide mechanistic insights into the role of innate immunity in kidney allograft survival, uncovering trained immunity as a potential therapeutic target for improving graft survival.
Project description:The innate immune system plays an essential role in regulating the immune responses to kidney transplantation, but the mechanisms through which innate immune cells influence long-term graft survival are unclear. The current study highlights the vital role of trained immunity in kidney allograft survival. Trained immunity describes the epigenetic and metabolic changes that innate immune cells undergo following an initial stimulus, allowing them have a stronger inflammatory response to subsequent stimuli. We stimulated healthy peripheral blood mononuclear cells with pretransplant and posttransplant serum of kidney transplant patients and immunosuppressive drugs in an in vitro trained immunity assay and measured tumor necrosis factor and interleukin 6 cytokine levels in the supernatant as a readout for trained immunity. We show that the serum of kidney transplant recipients collected 1 week after transplantation can suppress trained immunity. Importantly, we found that kidney transplant recipients whose serum most strongly suppressed trained immunity rarely experienced graft loss. This suppressive effect of posttransplant serum is likely mediated by previously unreported effects of immunosuppressive drugs. Our findings provide mechanistic insights into the role of innate immunity in kidney allograft survival, uncovering trained immunity as a potential therapeutic target for improving graft survival.
Project description:Complications associated with immunosuppression, specifically nephrotoxicity and infection risk, significantly affect graft and patient survival after kidney transplantation. We previously showed that tolerance could be induced and full donor chimerism, as well as immunosuppression withdrawal, was obtained in highly mismatched allograft recipients using a bioengineered stem cell product (FCRx). Gene expression profiles in renal biopsy samples from tolerance-induced FCRx recipients, paired donor organs before implant, and subjects under standard immunosuppression (SIS) without rejection and with acute rejection were compared. This dataset is part of the TransQST collection.
Project description:Despite much-improved protocols that broadly suppress the adaptive immune cells, most allografts are still lost to chronic rejection, in which macrophages have been prominently featured in the graft. In both clinical and pre-clinical studies, the graft-infiltrating macrophages often acquire diverse effector activities, especially the M2-biased programs, to mediate graft damage. But the precise mechanisms that regulate such programs remain incompletely defined. In the present study, we took a genome-wide approach to profile the epigenomic changes of M2-biased macrophages and identified the bromodomain and extra-terminal domain family protein-4 (BRD4) as a critical epigenetic regulator of M2 cells. Further in vitro studies revealed that either blocking BRD4 using a chemical inhibitor or conditional deletion of Brd4 in myeloid cells profoundly inhibited the induction of M2 cells. Importantly, in a fully MHC-mismatched heart transplant model, in which treatment with low doses of CTLA-4Ig led to the development of chronic rejection, inhibition of BDR4 in transplant recipients resulted in long-term heart allograft survival, which was associated with diminished intra-graft M2 cells and absence of histological features of chronic rejection. Together, our data suggest that macrophages can be epigenetically modified in favor of transplant survival and that BRD4 seems a promising therapeutic target for blocking chronic allograft rejection.
Project description:In clinical organ transplantation complete cessation of immunosuppressive therapy can be successfully accomplished in selected recipients providing a proof-of-principle that allograft tolerance is attainable in humans. The intra-graft molecular pathways associated with human allograft tolerance, however, have not been comprehensively studied before. In this study we analyzed sequential liver tissue samples collected from liver recipients enrolled in a prospective multicenter immunosuppressive withdrawal clinical trial. Tolerant and non-tolerant recipients differed in the intra-graft expression of genes involved in the regulation of iron homeostasis.These results point to a critical role of iron homeostasis in the regulation of intra-graft alloimmune responses in humans and provide a set of novel biomarkers to conduct drug-weaning trials in liver transplantation.
Project description:In clinical organ transplantation complete cessation of immunosuppressive therapy can be successfully accomplished in selected recipients providing a proof-of-principle that allograft tolerance is attainable in humans. The intra-graft molecular pathways associated with human allograft tolerance, however, have not been comprehensively studied before. In this study we analyzed sequential liver tissue samples collected from liver recipients enrolled in a prospective multicenter immunosuppressive withdrawal clinical trial. Tolerant and non-tolerant recipients differed in the intra-graft expression of genes involved in the regulation of iron homeostasis.These results point to a critical role of iron homeostasis in the regulation of intra-graft alloimmune responses in humans and provide a set of novel biomarkers to conduct drug-weaning trials in liver transplantation.