Tolerogenic dendritic cells in type 1 diabetes: no longer a concept

Artificial Tolerogenic Dendritic Cell-Derived Vesicles Prepared by High-Pressure Homogenization for Potent Immunotherapy of Type 1 Diabetes

Tolerogenic dendritic cells (tolDCs) have emerged as a promising immunotherapeutic approach for type 1 diabetes (T1D) by promoting immune tolerance and modulating autoimmune responses against pancreatic β cells. However, their clinical applications are challenged by various limitations including cell viability, scalability, and manufacturing complexities. As an alternative, tolDC-derived extracellular vesicles could address some limitations of cell-based therapies, though their application in T1D treatment remains unexplored. Here, we developed the artificial tolDC-derived vesicles (ACDVtolDC) by a high-pressure homogenization approach, which retained immunosuppressive properties with high yield production and stability that improved the scalability for potential clinical use. In both chemically induced (STZ) and spontaneous (NOD) T1D mouse models, ACDVtolDC exhibited abilities to reduce T cell infiltration by approximately 4-fold in the pancreas and re-establish the balance between regulatory and cytotoxic T cells to a healthy baseline, thereby preserving β cells and ameliorating T1D onset. Additionally, the therapeutic effect of ACDVtolDC was superior to that of the tolDC treatment. These findings highlighted ACDVtolDC as a potent vesicle-based immunotherapy for T1D, offering practical advantages over traditional tolDC therapies.

Exploiting regulatory T cells (Tregs): Cutting-edge therapy for autoimmune diseases

Regulatory T cells (Tregs) are a specialized subset of suppressive T cells that are essential for maintaining self-tolerance, regulating effector T cells, managing microbial infections, preventing tumors, allergies, and autoimmune disorders, and facilitating allograft transplantation. Disruptions in Treg function or abundance contribute to an imbalance between pathogenic and protective immune cells in autoimmune diseases. Recently, one promising treatment strategy to restore immune balance involves the selective expansion or manipulation of Tregs using low-dose IL-2 therapy, adoptive Treg cell transfer, and chimeric antigen receptor (CAR)-Treg approaches. Tregs have been shown in an increasing number of research studies to prevent or even treat a variety of disorders, such as tumors, autoimmune and allergic diseases, transplant rejection, and graft-versus-host disease. A thorough comprehension of Treg function is anticipated to provide clear prospects for effective Treg immunotherapy in the treatment of a wide range of diseases. This review provides an overview of Tregs biology, including their functions, suppressive mechanisms, phenotypic markers, as well as their involvement in disease settings. Furthermore, we discuss the therapeutic potential of different Treg subpopulations and their translational applications in the treatment of autoimmune diseases.

Salmonella-Based Vaccine: A Promising Strategy for Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by the progressive destruction of insulin-producing β-cells in the pancreas. Currently, no therapy exists to halt or cure T1D. Vaccination with diabetic autoantigens may offer protection against T1D development. Genetically modified, attenuated Salmonella utilizing the Salmonella-Pathogenicity Island 2 (SPI2)-encoded Type Three Secretion System (T3SS) can elicit robust immune responses, making it an attractive vaccine platform. Using SPI2-T3SS to deliver an autoantigen alongside immunomodulators and anti-CD3 antibodies induces antigen-specific regulatory T-cells. Our preclinical studies demonstrated the efficacy of a Salmonella-based vaccine in both preventing and reversing autoimmune diabetes in non-obese diabetic (NOD) mice while also exploring its genetic modifications, underlying mechanisms, and delivery strategies. This review evaluates the advantages of an oral T1D vaccine employing live, attenuated Salmonella for autoantigen delivery. We also discuss future directions for advancing this strategy in the treatment of other autoimmune diseases.

Immunomodulatory agents and cell therapy for patients with type 1 diabetes

Type 1 diabetes (TID) is a chronic disease caused by autoimmune destruction of pancreatic β-cells, that progresses in three stages: 1) stage 1: β-cell autoimmunity + normoglycemia; 2) stage 2: β-cell autoimmunity + mild dysglycemia; 3) stage 3: symptomatic disease + hyperglycemia. Interventions to prevent or cure T1D in the various stages of the disease have been pursued and may target the prevention of the destruction of β cells, regression of insulitis, preservation or recovery of β cells residual mass. Some therapies show promising results that might change the natural history and the approach to patients with T1D in the next few years. Teplizumab, a humanized monoclonal antibody that binds to CD3, was recently approved in the USA to delay Stage 3 T1D in individuals ≥ 8 years of age. Other non-cellular immunomodulatory therapies, both antigen-specific and non-specific, have shown interesting results either in patients with stage 2 or recent onset stage 3 T1D. Cell therapies such as non-myeloablative transplantation of autologous hematopoietic stem cells, mesenchymal stem cells, and tolerogenic dendritic cells have been also studied in these individuals, aiming immunomodulation. Stem cell-derived islet replacement therapy is promising for patients with long- standing T1D, especially with asymptomatic hypoglycemia not resolved by technology. This review aimed to provide updated information on the main immunomodulatory agents and cell therapy options for type 1 diabetes.

Immunotherapies for prevention and treatment of type 1 diabetes

Type 1 diabetes (T1D) is characterized by the autoimmune destruction of insulin-producing β-cells of the pancreatic islets necessitating lifelong insulin therapy. Despite significant advancements in diabetes technology with increasingly sophisticated methods of insulin delivery and glucose monitoring, people with T1D remain at risk of severe complications like hypoglycemia and diabetic ketoacidosis. There has long been an interest in altering the immune response in T1D to prevent or cure T1D across its various stages with limited efficacy. This review highlights immunomodulatory approaches over the years including the anti-CD3 monoclonal antibody teplizumab which is now approved to delay onset of T1DM and other interventions under current investigation.

Advances in Engineering Myeloid Cells for Cell Therapy Applications

Myeloid cells, including macrophages, neutrophils, dendritic cells, and myeloid-derived suppressor cells, play crucial roles in the innate immune system, contributing to immune defense, tissue homeostasis, and organ development. They have tremendous potential as therapeutic tools for diseases such as cancer and autoimmune disorders, but harnessing cell engineering strategies to enhance potency and expand applications is challenging. Recent advancements in stem cell research have made it possible to differentiate human embryonic stem cells and induce pluripotent stem cells into various cell types, including myeloid cells, offering a promising new approach to generate myeloid cells for cell therapy. In this review, we explore the latest techniques for the genetic engineering of myeloid cells, discussing both established and emerging methodologies. We examine the challenges faced in this field and the therapeutic potential of engineered myeloid cells. We also describe examples of engineered macrophages, neutrophils, and dendritic cells in various disease contexts. By providing a detailed overview of the current state and future directions, we aim to highlight progress and ongoing efforts toward harnessing the full therapeutic potential of genetically engineered myeloid cells.

Targeting macrophages with phosphatidylserine-rich liposomes as a potential antigen-specific immunotherapy for type 1 diabetes

Type 1 diabetes (T1D) results from a breakdown in immunological tolerance, with pivotal involvement of antigen-presenting cells. In this context, antigen-specific immunotherapies have been developed to arrest autoimmunity, such as phosphatidylserine (PS)-liposomes. However, the role of certain antigen-presenting cells in immunotherapy, particularly human macrophages (Mφ) in T1D remains elusive. The aim of this study was to determine the role of Mφ in antigen-specific immune tolerance and T1D. To that end, we evaluated Mφ ability to capture apoptotic-body mimicking PS-liposomes in mice and conducted a phenotypic and functional characterisation of four human monocyte-derived Mφ (MoMφ) subpopulations (M0, M1, M2a and M2c) after PS-liposomes uptake. Our findings in mice identified Mφ as the most phagocytic cell subset in the spleen and liver. In humans, while phagocytosis rates were comparable between T1D and control individuals, PS-liposome capture dynamics differed among Mφ subtypes, favouring inflammatory (M1) and deactivated (M2c) Mφ. Notably, high nanoparticle concentrations did not affect macrophage viability. PS-liposome uptake by Mφ induced alterations in membrane molecule expression related to immunoregulation, reduced secretion of IL-6 and IL-12, and diminished autologous T-cell proliferation in the context of autoantigen stimulation. These results underscore the tolerogenic effects of PS-liposomes and emphasize their potential to target human Mφ, providing valuable insights into the mechanism of action of this preclinical immunotherapy.

Mechanism of Action of Oral Salmonella-Based Vaccine to Prevent and Reverse Type 1 Diabetes in NOD Mice

A combination therapy of preproinsulin (PPI) and immunomodulators (TGFβ+IL10) orally delivered via genetically modified Salmonella and anti-CD3 promoted glucose balance in in NOD mice with recent onset diabetes. The Salmonella bacteria were modified to express the diabetes-associated antigen PPI controlled by a bacterial promoter in conjunction with over-expressed immunomodulating molecules. The possible mechanisms of action of this vaccine to limit autoimmune diabetes remained undefined. In mice, the vaccine prevented and reversed ongoing diabetes. The vaccine-mediated beneficial effects were associated with increased numbers of antigen-specific CD4+CD25+Foxp3+ Tregs, CD4+CD49b+LAG3+ Tr1-cells, and tolerogenic dendritic-cells (tol-DCs) in the spleens and lymphatic organs of treated mice. Despite this, the immune response to Salmonella infection was not altered. Furthermore, the vaccine effects were associated with a reduction in islet-infiltrating lymphocytes and an increase in the islet beta-cell mass. This was associated with increased serum levels of the tolerogenic cytokines (IL10, IL2, and IL13) and chemokine ligand 2 (CCL2) and decreased levels of inflammatory cytokines (IFNγ, GM-CSF, IL6, IL12, and TNFα) and chemokines (CXCL1, CXCL2, and CXCL5). Overall, the data suggest that the Salmonella-based vaccine modulates the immune response, reduces inflammation, and promotes tolerance specifically to an antigen involved in autoimmune diabetes.

Schistosoma-related molecules as a new strategy to combat type 1 diabetes through immune regulation

The study of immune regulation mechanisms induced by parasites may help develop new treatment methods for inflammatory diseases including type 1 diabetes, which is related to type 1 immune responses. The negative correlation between schistosomiasis infection and type 1 diabetes has been confirmed, and the mechanism of Schistosoma-mediated prevention of type 1 diabetes may be related to the adaptive and innate immune systems. Schistosoma-related molecules affect immune cell composition and macrophage polarization and stimulate an increase in natural killer T cells. Furthermore, Schistosoma-related molecules can regulate the adaptive immune responses related to the prevention of type 1 diabetes and change the Th1/Th2 and Th17/Treg axis. Our previous review showed the role of regulatory T cells in the protective of type 1 diabetes mediated by Schistosoma. Here, we aim to review the other mechanisms of schistosomiasis infection and Schistosoma-related products in regulating the immune response associated with the treatment of type 1 diabetes.