IFN-?-induced iNOS expression in mouse regulatory macrophages prolongs allograft survival in fully immunocompetent recipients.
ABSTRACT: Mouse monocytes exposed to macrophage colony-stimulating factor (M-CSF) and interferon-? (IFN-?) were driven to a novel suppressor phenotype. These regulatory macrophages (M regs) expressed markers distinguishing them from M0-, M1-, and M2-polarized macrophages and monocyte-derived dendritic cells (DCs). M regs completely suppressed polyclonal T cell proliferation through an inducible nitric oxide synthase (iNOS)-dependent mechanism. Additionally, M regs eliminated cocultured T cells in an allospecific fashion. In a heterotopic heart transplant model, a single intravenous administration of 5 × 10(6) donor-strain M regs before transplantation significantly prolonged allograft survival in fully immunocompetent recipients using both the stringent C3H-to-BALB/c (32.6 ± 4.5 versus 8.7 ± 0.2 days) and B6-to-BALB/c (31.1 ± 12 versus 9.7 ± 0.4 days) strain combinations. Nos2-deficient M regs did not prolong allograft survival, proving that M reg function in vivo is iNOS-dependent and mediated by living cells. M regs were detectable for at least 2 weeks postinfusion in allogeneic recipients. In their origin, development, phenotypic relationship with other in vitro-derived macrophages and functions, there are solid grounds to assert a near-equivalence of mouse and human M regs. It is concluded that mouse M regs represent a novel, phenotypically distinct subset of suppressor macrophages. Clinical applications of M reg therapy as an adjunct immunosuppressive therapy are currently being investigated within The ONE Study.
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. Overall design: 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. The dataset comprises 36 samples divided into twelve sample groups each representing a certain monocyte/macrophage subtype
Project description:Graft rejection by the immune system is a major cause of transplant failure. Lifelong immunosuppression decreases the incidence of graft rejection; however, nonspecific immunosuppression results in increased susceptibly to infection and cancer. Regulatory T cells (T(regs)), which suppress the activation of the immune system and induce tolerance, are currently under evaluation for use in clinical transplantation. Ex vivo expanded polyclonal T(regs) that are introduced into transplant recipients alter the balance of T effector cells to T(regs); however, experimental data suggest that alloantigen-specific T(regs) would be more effective at preventing graft rejection. We have developed a method to enrich alloantigen-specific human T(regs) based on the coexpression of activation markers, CD69 and CD71. These T(regs) could be readily expanded in vitro and demonstrated potent antigen-specific suppression. In a humanized mouse model of alloimmune-mediated injury of human skin grafts, alloantigen-specific T(regs) resulted in a significant reduction in clinically relevant indicators of dermal tissue injury when compared with polyclonal T(regs), restoring a histology comparable to healthy skin. This method of human allospecific T(reg) selection should be scalable to the clinic. The improved in vivo efficacy of alloantigen-specific T(regs) over polyclonal T(regs) shown here suggests that generating "customized" T(regs) with defined anti-donor allospecificities may improve current practice in clinical immunotherapy.
Project description:Optimal immune-based therapies for type 1 diabetes (T1D) should restore self-tolerance without inducing chronic immunosuppression. CD4<sup>+</sup>Foxp3<sup>+</sup> regulatory T cells (T<sub>regs</sub>) are a key cell population capable of facilitating durable immune tolerance. However, clinical trials with expanded T<sub>regs</sub> in T1D and solid-organ transplant recipients are limited by poor T<sub>reg</sub> engraftment without host manipulation. We showed that T<sub>reg</sub> engraftment and therapeutic benefit in nonautoimmune models required ablative host conditioning. Here, we evaluated T<sub>reg</sub> engraftment and therapeutic efficacy in the nonobese diabetic (NOD) mouse model of autoimmune diabetes using nonablative, combinatorial regimens involving the anti-CD3 (?CD3), cyclophosphamide (CyP), and IAC (IL-2/JES6-1) antibody complex. We demonstrate that ?CD3 alone induced substantial T-cell depletion, impacting both conventional T cells (T<sub>conv</sub>) and T<sub>regs</sub>, subsequently followed by more rapid rebound of T<sub>regs</sub> Despite robust depletion of host T<sub>conv</sub> and host T<sub>regs</sub>, donor T<sub>regs</sub> failed to engraft even with interleukin-2 (IL-2) support. A single dose of CyP after ?CD3 depleted rebounding host T<sub>regs</sub> and resulted in a 43-fold increase in donor T<sub>reg</sub> engraftment, yet polyclonal donor T<sub>regs</sub> failed to reverse diabetes. However, infusion of autoantigen-specific T<sub>regs</sub> after ?CD3 alone resulted in robust T<sub>reg</sub> engraftment within the islets and induced remission in all mice. This novel combinatorial therapy promotes engraftment of autoantigen-specific donor T<sub>regs</sub> and controls islet autoimmunity without long-term immunosuppression.
Project description:It has been recently shown (Seddiki, N., B. Santner-Nanan, J. Martinson, J. Zaunders, S. Sasson, A. Landay, M. Solomon, W. Selby, S.I. Alexander, R. Nanan, et al. 2006. J. Exp. Med. 203:1693-1700.) that the expression of interleukin (IL) 7 receptor (R) alpha discriminates between two distinct CD4 T cell populations, both characterized by the expression of CD25, i.e. CD4 regulatory T (T reg) cells and activated CD4 T cells. T reg cells express low levels of IL-7Ralpha, whereas activated CD4 T cells are characterized by the expression of IL-7Ralpha(high). We have investigated the distribution of these two CD4 T cell populations in 36 subjects after liver and kidney transplantation and in 45 healthy subjects. According to a previous study (Demirkiran, A., A. Kok, J. Kwekkeboom, H.J. Metselaar, H.W. Tilanus, and L.J. van der Laan. 2005. Transplant. Proc. 37:1194-1196.), we observed that the T reg CD25(+)CD45RO(+)IL-7Ralpha(low) cell population was reduced in transplant recipients (P < 0.00001). Interestingly, the CD4(+)CD25(+)CD45RO(+)IL-7Ralpha(high) cell population was significantly increased in stable transplant recipients compared with healthy subjects (P < 0.00001), and the expansion of this cell population was even greater in patients with documented humoral chronic rejection compared with stable transplant recipients (P < 0.0001). The expanded CD4(+)CD25(+)CD45RO(+)IL-7Ralpha(high) cell population contained allospecific CD4 T cells and secreted effector cytokines such as tumor necrosis factor alpha and interferon gamma, thus potentially contributing to the mechanisms of chronic rejection. More importantly, CD4(+)IL-7Ralpha(+)and CD25(+)IL-7Ralpha(+) cells were part of the T cell population infiltrating the allograft of patients with a documented diagnosis of chronic humoral rejection. These results indicate that the CD4(+)CD25(+)IL-7Ralpha(+) cell population may represent a valuable, sensitive, and specific marker to monitor allospecific CD4 T cell responses both in blood and in tissues after organ transplantation.
Project description:Several types of myeloid suppressor cell are currently being developed as cell-based immunosuppressive agents. Despite detailed knowledge about the molecular and cellular functions of these cell types, expert opinions differ on how to best implement such therapies in solid organ transplantation. Efforts in our laboratory to develop a cell-based medicinal product for promoting tolerance in renal transplant patients have focused on a type of suppressor macrophage, which we call the regulatory macrophage (M reg). Our favoured clinical strategy is to administer donor-derived M regs to recipients one week prior to transplantation. In contrast, many groups working with tolerogenic dendritic cells (DCs) advocate post-transplant administration of recipient-derived cells. A third alternative, using myeloid-derived suppressor cells, presumably demands that cells are given around the time of transplantation, so that they can infiltrate the graft to create a suppressive environment. On present evidence, it is not possible to say which cell type and treatment strategy might be clinically superior. This review seeks to position our basic scientific and early-stage clinical studies of human regulatory macrophages within the broader context of myeloid suppressor cell therapy in transplantation.
Project description:Different profiles of alloantibody responses are observed in the clinic, with those that persist, often despite targeted treatment, associated with poorer long-term transplant outcomes. Although such responses would suggest an underlying germinal center (GC) response, the relationship to cellular events within the allospecific B cell population is unclear. Here we examine the contribution of germinal center (GC) humoral alloimmunity to chronic antibody mediated rejection (AMR). A murine model of chronic AMR was developed in which T cell deficient (Tcrbd -/-) C57BL/6 recipients were challenged with MHC-mismatched BALB/c heart allografts and T cell help provided by reconstituting with 103 "TCR75" CD4 T cells that recognize self-restricted allopeptide derived from the H-2Kd MHC class I alloantigen. Reconstituted recipients developed Ig-switched anti-Kd alloantibody responses that were slow to develop, but long-lived, with confocal immunofluorescence and flow cytometric characterization of responding H-2Kd-allospecific B cells confirming persistent splenic GC activity. This was associated with T follicular helper (TFH) cell differentiation of the transferred TCR75 CD4 T cells. Heart grafts developed progressive allograft vasculopathy, and were rejected chronically (MST 50 days), with explanted allografts displaying features of humoral vascular rejection. Critically, late alloantibody responses were abolished, and heart grafts survived indefinitely, in recipients reconstituted with Sh2d1a -/- TCR75 CD4 T cells that were genetically incapable of providing TFH cell function. The GC response was associated with affinity maturation of the anti-Kd alloantibody response, and its contribution to progression of allograft vasculopathy related principally to secretion of alloantibody, rather than to enhanced alloreactive T cell priming, because grafts survived long-term when B cells could present alloantigen, but not secrete alloantibody. Similarly, sera sampled at late time points from chronically-rejecting recipients induced more vigorous donor endothelial responses in vitro than sera sampled earlier after transplantation. In summary, our results suggest that chronic AMR and progression of allograft vasculopathy is dependent upon allospecific GC activity, with critical help provided by TFH cells. Clinical strategies that target the TFH cell subset may hold therapeutic potential. This work is composed of two parts, of which this is Part II. Please read also Part I: Alsughayyir et al., 2019.
Project description:Tissue resident lymphocytes are present within many organs, and are presumably transferred at transplantation, but their impact on host immunity is unclear. Here, we examine whether transferred donor natural regulatory CD4 T cells (nT-regs) inhibit host alloimmunity and prolong allograft survival. Transfer of donor-strain lymphocytes was first assessed by identifying circulating donor-derived CD4 T cells in 21 consecutive human lung transplant recipients, with 3 patterns of chimerism apparent: transient, intermediate, and persistent (detectable for up to 6 weeks, 6 months, and beyond 1 year, respectively). The potential for transfer of donor nT-regs was then confirmed by analysis of leukocyte filters recovered from ex vivo normothermic perfusion circuits of human kidneys retrieved for transplantation. Finally, in a murine model of cardiac allograft vasculopathy, depletion of donor CD4 nT-regs before organ recovery resulted in markedly accelerated heart allograft rejection and augmented host effector antibody responses. Conversely, adoptive transfer or purified donor-strain nT-regs inhibited host humoral immunity and prolonged allograft survival, and more effectively so than following administration of recipient nT-regs. In summary, following transplantation, passenger donor-strain nT-regs can inhibit host adaptive immune responses and prolong allograft survival. Isolated donor-derived nT-regs may hold potential as a cellular therapy to improve transplant outcomes.
Project description:Regulatory T cells (T(regs)) can suppress a wide variety of cell types, in diverse organ sites and inflammatory conditions. Whereas T(regs) possess multiple suppressive mechanisms, the number required for maximal function is unclear. Furthermore, whether any interrelationship or cross-regulatory mechanisms exist to orchestrate and control their utilization is unknown. In this study, we assessed the functional capacity of T(regs) lacking the ability to secrete both IL-10 and IL-35, which individually are required for maximal T(reg) activity. Surprisingly, IL-10/IL-35 double-deficient T(regs) were fully functional in vitro and in vivo. Loss of IL-10 and IL-35 was compensated for by a concurrent increase in cathepsin E (Ctse) expression, enhanced TRAIL (Tnfsf10) expression, and soluble TRAIL release, rendering IL-10/IL-35 double-deficient T(regs) functionally dependent on TRAIL in vitro and in vivo. Lastly, whereas C57BL/6 T(regs) are normally IL-10/IL-35 dependent, BALB/c T(regs), which express high levels of cathepsin E and enhanced TRAIL expression, are partially TRAIL dependent by default. These data reveal that cross-regulatory pathways exist that control the utilization of suppressive mechanisms, thereby providing T(reg) functional plasticity.
Project description:The role of regulatory T cells (T(regs)) in human colon cancer (CC) remains controversial: high densities of tumor-infiltrating T(regs) can correlate with better or worse clinical outcomes depending on the study. In mouse models of cancer, T(regs) have been reported to suppress inflammation and protect the host, suppress T cells and protect the tumor, or even have direct cancer-promoting attributes. These different effects may result from the presence of different T(reg) subsets. We report the preferential expansion of a T(reg) subset in human CC with potent T cell-suppressive, but compromised anti-inflammatory, properties; these cells are distinguished from T(regs) present in healthy donors by their coexpression of Foxp3 and ROR?t. T(regs) with similar attributes were found to be expanded in mouse models of hereditary polyposis. Indeed, ablation of the ROR?t gene in Foxp3(+) cells in polyp-prone mice stabilized T(reg) anti-inflammatory functions, suppressed inflammation, improved polyp-specific immune surveillance, and severely attenuated polyposis. Ablation of interleukin-6 (IL-6), IL-23, IL-17, or tumor necrosis factor-? in polyp-prone mice reduced polyp number but not to the same extent as loss of ROR?t. Surprisingly, loss of IL-17A had a dual effect: IL-17A-deficient mice had fewer polyps but continued to have ROR?t(+) T(regs) and developed invasive cancer. Thus, we conclude that ROR?t has a central role in determining the balance between protective and pathogenic T(regs) in CC and that T(reg) subtype regulates inflammation, potency of immune surveillance, and severity of disease outcome.