Intragraft memory-like CD127hiCD4+Foxp3+ Tregs maintain transplant tolerance.

CD4+Foxp3+ regulatory T cells (Tregs) play an essential role in suppressing transplant rejection, but their role within the graft and heterogeneity in tolerance are poorly understood. Here, we compared phenotypic and transcriptomic characteristics of Treg populations within lymphoid organs and grafts in an islet xenotransplant model of tolerance. We showed Tregs were essential for tolerance induction and maintenance.

Human HLA-DR+CD27+ regulatory T cells show enhanced antigen-specific suppressive function.

Regulatory T cells (Tregs) have potential for the treatment of autoimmune diseases and graft rejection. Antigen specificity and functional stability are considered critical for their therapeutic efficacy. In this study, expansion of human Tregs in the presence of porcine PBMCs (xenoantigen-expanded Tregs, Xn-Treg) allowed the selection of a distinct Treg subset, coexpressing the activation/memory surface markers HLA-DR and CD27 with enhanced proportion of FOXP3+Helios+ Tregs.

Cellular Immune Responses in Islet Xenograft Rejection.

Porcine islets surviving the acute injury caused by humoral rejection and IBMIR will be subjected to cellular xenograft rejection, which is predominately mediated by CD4 T cells and is characterised by significant infiltration of macrophages, B cells and T cells (CD4 and CD8). Overall, the response is different compared to the alloimmune response and more difficult to suppress. Activation of CD4 T cells is both by direct and indirect antigen presentation.

Enhancing and stabilization of cord blood regulatory T-cell suppressive function by human mesenchymal stem cell (MSC)-derived exosomes.

FOXP3+ regulatory T cells (Tregs) are central to maintaining peripheral tolerance and immune homeostasis. They have the potential to be developed as a cellular therapy to treat various clinical ailments such as autoimmune disorders, inflammatory diseases and to improve transplantation outcomes. However, a major question remains whether Tregs can persist and exert their function effectively in a disease state, where a broad spectrum of inflammatory mediators could inactivate Tregs.

Benefit of Belatacept in Cord Blood-Derived Regulatory T Cell-Mediated Suppression of Alloimmune Response.

The role of Regulatory T cells (Tregs) in tolerance induction post-transplantation is well-established, but Tregs adoptive transfer alone without combined immunosuppressants have failed so far in achieving clinical outcomes. Here we applied a set of well-designed criteria to test the influence of commonly used immunosuppressants (belatacept, tacrolimus, and mycophenolate) on cord blood-derived Tregs (CB-Tregs). Our study shows that while none of these immunosuppressants modulated the stability and expression of homing molecules by CB-Tregs, belatacept met all other selective criteria, shown by its ability to enhance CB-Tregs-mediated in vitro suppression of the allogeneic response without affecting their viability, proliferation, mitochondrial metabolism and expression of functional markers.

Low-Dose Interleukin-2 Combined With Rapamycin Led to an Expansion of CD4CD25FOXP3 Regulatory T Cells and Prolonged Human Islet Allograft Survival in Humanized Mice.

Islet transplantation is an emerging therapy for type 1 diabetes and hypoglycemic unawareness. However, a key challenge for islet transplantation is cellular rejection and the requirement for long-term immunosuppression. In this study, we established a diabetic humanized NOD-scidIL2Rγ (NSG) mouse model of T-cell-mediated human islet allograft rejection and developed a therapeutic regimen of low-dose recombinant human interleukin-2 (IL-2) combined with low-dose rapamycin to prolong graft survival.

Intervention for early diabetic nephropathy by mesenchymal stem cells in a preclinical nonhuman primate model.

Background: Diabetic nephropathy (DN) is one of the most severe chronic diabetic complications and the main cause of end-stage renal disease. Chronic inflammation plays a key role in the development of DN. However, few treatment strategies are available; therefore, new and effective strategies to ameliorate DN at the early stage must be identified.

Standardisation of flow cytometry for whole blood immunophenotyping of islet transplant and transplant clinical trial recipients.

Understanding the immunological phenotype of transplant recipients is important to improve outcomes and develop new therapies. Immunophenotyping of whole peripheral blood (WPB) by flow cytometry is a rapid method to obtain large amounts of data relating to the outcomes of different transplant treatments with limited patient impact. Healthy individuals and patients with type 1 diabetes (T1D) enrolled in islet transplantation were recruited and WPB was collected.

Human mesenchymal-stem-cells-derived exosomes are important in enhancing porcine islet resistance to hypoxia.

Background: Hypoxia-induced damage is one of the key factors associated with islet graft dysfunction. Mesenchymal stem cells (MSCs) could be used to enhance the therapeutic effect of islet transplantation due to their paracrine potential such as exosomes. In this study, we investigated whether exosomes from human umbilical cord-derived MSC-conditioned medium (hu-MSC-CM) could increase the survival and function of neonatal porcine islet cell clusters (NICCs) exposed to hypoxia.

Hypoxia potentiates LPS-induced inflammatory response and increases cell death by promoting NLRP3 inflammasome activation in pancreatic β cells.

Hypoxia and islet inflammation are involved in β-cell failure in type 2 diabetes (T2D). Elevated plasma LPS levels have been verified in patients with T2D, and hypoxia occurs in islets of diabetic mice. Activation of inflammasomes in ischemic or hypoxic conditions was identified in various tissues.

Culturing with modified EGM2 medium enhances porcine neonatal islet-like cell clusters resistance to apoptosis in islet xenotransplantation.

Background: Neonatal pig islet-like cell clusters (NICC) are an attractive source of insulin-producing tissue for potential transplantation treatment of type 1 diabetic patients. However, a considerable loss of NICC after their transplantation due to apoptosis resulted from islet isolation and instant blood-mediated inflammatory reaction remains to be overcome.

Methods: EGM2 medium depleted with hydrocortisone and supplemented with 50 mmol/L isobutylmethylxanthine, 10 mmol/L nicotinamide, and 10 mmol/L glucose was used to culture NICC at day 1, the day after isolation and changed every other day.

Ex vivo-expanded baboon CD39 + regulatory T cells prevent rejection of porcine islet xenografts in NOD-SCID IL-2rγ mice reconstituted with baboon peripheral blood mononuclear cells.

Background: A high immunosuppressive burden is required for long-term islet xenograft survival in non-human primates even using genetically modified donor pigs.

Aims: We aimed to investigate the capacity of baboon regulatory T cells (Treg) to suppress islet xenograft rejection, thereby developing a potential immunoregulatory or tolerance therapy that could be evaluated in NHP models of xenotransplantation.

Materials & Methods: Baboon Treg expanded with stimulation by porcine peripheral blood mononuclear cells (PBMC) were characterized by cell phenotyping and suppressive activity assays in vitro.

Regulatory T-Cell Levels in the Longest Surviving Asian Patient After Heart-Lung Transplant.

Heart-lung transplant is the most effective therapy for patients with end-stage cardiopulmonary disease. Here, we report an initial assessment of a 31-year-old man who had survived more than 11 years after heart-lung transplant, which represents the longest survival time in this procedure in Asian studies. At his 11th anniversary after transplant, extensive tests were carried out, especially to detect regulatory T-cell levels for the first time in a surviving heart-lung transplant recipient.

Human regulatory macrophages are potent in suppression of the xenoimmune response via indoleamine-2,3-dioxygenase-involved mechanism(s).

Background: For xenotransplantation to truly succeed, we must develop immunomodulatory strategies to suppress the xenoimmune response but by minimizing immunosuppression over the long term. Regulatory macrophages (Mreg) have been shown to suppress polyclonal T-cell proliferation in vitro and prolong allograft survival in vivo. However, the question of whether they are capable of suppressing xenoimmune responses remains unknown.

A preclinical evaluation of alternative site for islet allotransplantation.

The bone marrow cavity (BMC) has recently been identified as an alternative site to the liver for islet transplantation. This study aimed to compare the BMC with the liver as an islet allotransplantation site in diabetic monkeys. Diabetes was induced in Rhesus monkeys using streptozocin, and the monkeys were then divided into the following three groups: Group1 (islets transplanted in the liver with immunosuppressant), Group 2 (islets transplanted in the tibial BMC), and Group 3 (islets transplanted in the tibial BMC with immunosuppressant).

Bone marrow chimerism as a strategy to produce tolerance in solid organ allotransplantation.

Purpose Of Review: Clinical transplant tolerance has been most successfully achieved combining hematopoietic chimerism with kidney transplantation. This review outlines this strategy in animal models and human transplantation, and possible clinical challenges.

Recent Findings: Kidney transplant tolerance has been achieved through chimerism in several centers beginning with Massachusetts General Hospital's success with mixed chimerism in human leukocyte antigen (HLA)-mismatched patients and the Stanford group with HLA-matched patients, and the more recent success of the Northwestern protocol achieving full chimerism.

In Vivo Costimulation Blockade-Induced Regulatory T Cells Demonstrate Dominant and Specific Tolerance to Porcine Islet Xenografts.

Background: Although islet xenotransplantation is a promising therapy for type 1 diabetes, its clinical application has been hampered by cellular rejection and the requirement for high levels of immunosuppression. The aim of this study was to determine the role of Foxp3 regulatory T (Treg) cells in costimulation blockade-induced dominant tolerance to porcine neonatal islet cell cluster (NICC) xenografts in mice.

Methods: Porcine-NICC were transplanted under the renal capsule of BALB/c or C57BL/6 recipients and given a single dose of CTLA4-Fc at the time of transplant and 4doses of anti-CD154 mAb to day 6.

Regulatory T cells in kidney disease and transplantation.

Regulatory T cells (Tregs) have been shown to be important in maintaining immune homeostasis and preventing autoimmune disease, including autoimmune kidney disease. It is also likely that they play a role in limiting kidney transplant rejection and potentially in promoting transplant tolerance. Although other subsets of Tregs exist, the most potent and well-defined Tregs are the Foxp3 expressing CD4(+) Tregs derived from the thymus or generated peripherally.

Large-scale in vitro expansion of human regulatory T cells with potent xenoantigen-specific suppression.

Xenotransplantation is a potential solution to the organ donor shortage. Immunosuppression is required for successful application of xenotransplantation but may lead to infection and cancer. Thus, strategies for immune tolerance induction need to be developed.

Thyroid-stimulating hormone regulates hepatic bile acid homeostasis via SREBP-2/HNF-4α/CYP7A1 axis.

Background & Aims: Bile acids (BAs) play a crucial role in dietary fat digestion and in the regulation of lipid, glucose, and energy metabolism. Thyroid-stimulating hormone (TSH) is a hormone produced by the anterior pituitary gland that directly regulates several metabolic pathways. However, the impact of TSH on BA homeostasis remains largely unknown.

[Isolation, amplification and identification of human natural CD4⁺CD25⁺ regulatory T cells in vitro].

Objective: To establish a method for in vitro expansion of human natural CD4⁺CD25⁺ T regulatory cell (Treg) cells for clinical study and immunotherapy.

Methods: Human natural CD4⁺CD25⁺ Treg were isolated from peripheral blood monocyte cells (PBMCs) by magnetic activated cell sorting (MACS) and expanded by CD3/CD28 expansion beads, IL-2 and rapamycin. The number and the viability of the freshly isolated and expanded Treg were detemined by trypan blue staining.

Increased peripheral proinflammatory T helper subsets contribute to cardiovascular complications in diabetic patients.

Background: Coronary atherosclerotic heart disease (CHD) is one of the major concerns in type 2 diabetes (T2D). The systemic chronic inflammation has been postulated to bridge the increased risk of cardiovascular disease and T2D. We formulated that increased peripheral proinflammatory T helper subsets contributed to the development of cardiovascular complications in diabetic patients.