A phase 2 randomized trial with autologous polyclonal expanded regulatory T cells in children with new-onset type 1 diabetes

Expression of an interleukin-2 partial agonist enhances regulatory T cell persistence and efficacy in mouse autoimmune models

Regulatory T (Treg)-based cell therapy holds promise for autoimmune and inflammatory diseases, yet challenges remain regarding the functional stability and persistence of transferred Tregs. Here we engineer Tregs to express a partial agonist form of IL-2 (IL-2pa) to enhance persistence while avoiding toxicity from excessive signaling. Mouse Tregs expressing wild-type IL-2 (Tregs-IL2wt) have only a transient growth advantage, limited by toxicity from likely excessive signaling. By contrast, mouse Tregs-IL2pa exhibit sustained expansion, long-term survival in immunocompetent mice for over a year, and bystander expansion of endogenous Tregs. Tregs-IL2pa maintain a stable activated phenotype, Treg-specific demethylation, and a diverse TCR repertoire. In vivo, prophylactic transfer of Tregs-IL2pa ameliorates multi-organ autoimmunity in a Treg depletion-induced mouse autoimmune model. Lastly, compared with control Treg, human Tregs-IL2pa show enhanced survival in the IL-2-depleted environment of immune-deficient mice and improved control of xenogeneic graft-versus-host disease. Our results thus show that IL-2pa self-sufficiency enhances the stability, durability and efficacy of Treg therapies in preclinical settings.

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.

Type 1 Diabetes: A Guide to Autoimmune Mechanisms for Clinicians

Type 1 diabetes (T1D) results from the destruction of pancreatic beta cells by autoreactive T lymphocytes, leading to insulin deficiency and lifelong insulin dependence. It develops in genetically predisposed individuals, triggered by environmental or immunological factors. Although the exact causes of T1D remain unknown, the autoimmune pathogenesis of the disease is clearly indicated by the genetic risk conferred by allelic human leukocyte antigens (HLA), the almost obligatory presence of islet cell autoantibodies (AAbs) and immune cell infiltration of pancreatic islets from patients. At the same time, epidemiological data point to a role of environmental factors, notably enteroviral infections, in the disease, although precise causative links between specific pathogens and T1D have been difficult to establish. Studies of human pancreas organs from patients made available through repositories and the advent of high-dimensional high-throughput technologies for genomic and proteomic studies have significantly elucidated our understanding of the disease in recent years and provided mechanistic insights that can be exploited for innovative targeted therapeutic approaches. This short overview will summarise current salient knowledge on immune cell and beta cell dysfunction in T1D pathogenesis. PLAIN LANGUAGE SUMMARY: Type 1 diabetes (T1D) is a chronic disease where the body's own immune system attacks and destroys the insulin-producing beta cells in the pancreas. This leads to a lack of insulin, a hormone essential for regulating blood sugar, which means people with T1D need insulin for life. The disease can develop at any age but is most diagnosed in children and young adults. Despite advances in treatment, T1D still significantly reduces life expectancy, especially in countries with fewer healthcare resources. T1D develops in people with a genetic predisposition, often triggered by environmental factors such as viral infections or changes in the gut microbiome. The disease progresses silently through three stages: Stage 1: Autoantibodies to beta cell components appear, signalling the immune system is reacting against the pancreas, but there are no symptoms; Stage 2: Beta cell function starts to decline, but fasting blood sugar is still normal; Stage 3: Enough beta cells are destroyed that fasting blood sugar rises, and symptoms of diabetes appear. The risk of progressing from stage 1 to full-blown diabetes is about 35-50% within five years, and even higher from stage 2. Over 60 genes are linked to T1D risk, most of which affect how the immune system works. The strongest genetic risk comes from specific versions of histocompatibility genes, which help the immune system distinguish between the body's own cells and invaders. Some types of these genes make it easier for the immune system to mistakenly attack beta cells. However, 90% of people diagnosed with T1D have no family member with T1D, showing that genetics is only part of the story. Environmental factors also play a big role. For example, certain viral infections, especially with viruses infecting the intestine, are associated with a higher risk of developing T1D. The gut microbiome - the community of bacteria living in our intestines - also influences risk, with healthier, more diverse microbiomes appearing to offer some protection. In T1D, immune cells - especially so-called T lymphocytes - mistake beta cells in the pancreas for threats and destroy them. This process is called autoimmunity. The attack is often reflected by the presence of autoantibodies against proteins found in beta cells. Over time, as more beta cells are lost, the body can no longer produce enough insulin, leading to the symptoms of diabetes. Interestingly, not all people with T1D have the same pattern of disease. For example, children diagnosed before age 7 often have more aggressive disease, more autoantibodies, and stronger genetic risk factors than those diagnosed later. Much of our understanding of T1D has come from studying animal models, but new technologies now allow researchers to study human pancreas tissue and blood immune cells in greater detail. Scientists are also exploring how the gut microbiome, diet, and environmental exposures contribute to T1D risk and progression. Treatment currently focuses on replacing insulin, but researchers are working on therapies that target the immune system or aim to protect or replace beta cells. Strategies include immunotherapy, gene therapy, and even modifying the gut microbiome. The goal is to prevent or reverse the disease, not just manage its symptoms. In summary, T1D is a complex autoimmune disease influenced by both genes and the environment. It progresses silently before symptoms appear, and while insulin therapy is life-saving, new research is paving the way for treatments that could one day halt or even prevent the disease.

Advances in Regulatory Cell Therapy for Type 1 Diabetes: Emerging Strategies and Future Directions

Type 1 diabetes (T1D) is an autoimmune disorder characterized by the destruction of insulin-producing β-cells in the pancreas. Despite advances in insulin therapy and β-cell replacement, a definitive cure addressing the underlying cause of the disease, that is the loss of immune tolerance to β-cells remains elusive. Emerging strategies to reshape the immune response to pancreatic autoantigens include the adoptive transfer of ex vivo cultured regulatory cells, either mesenchymal stem cells (MSCs), regulatory T cells (Tregs), or dendritic cells (DCs), collectively known as regulatory cell therapy. This review aims to provide an overview of the regulatory cell-based approaches for T1D currently under development. Although several clinical trials have demonstrated the safety of in vivo administration of regulatory cells to T1D patients, only mild signs of efficacy have been reported. The most promising results were observed in patients with shorter disease duration and higher residual β-cell mass, suggesting that early interventions may result in clinical benefit. Significant challenges remain, including the long-term efficacy and stability of the infused products. In the future, approaches combining regulatory cell-based therapies with immunomodulatory agents or strategies to restore the damaged insulin-producing cells may hold the key to achieving a functional cure for T1D.

Therapeutic application of regulatory T cell in osteoarthritis

Regulatory T cells (Tregs) are the specific T cell population that suppress inflammatory immunity. Independent of their inhibitory activities, Tregs exhibit unique capacity to repair tissue damage. Rapid progresses are made in the processing and engineering of Tregs for clinical applications. Tregs have been used in the treatment of autoimmune diseases, transplantation rejection and graft-versus-host disease. Osteoarthritis is one of the major diseases that affect at least 600 million people worldwide. Osteoarthritis is characterized by physical erosion of cartilage, accompanied with chronic and low-grade inflammation. Tregs possess abilities to increase osteoclast differentiation and bone resorption, repair bone physical damage, and increase bone mass. Tregs are therefore candidate therapeutics for osteoarthritis for both inflammation resolution and tissue repairing. In this review, we will summarize the recent development in using Tregs in immunotherapy, and the potential of using Tregs in osteoarthritis.

Emerging Immunotherapies for Disease Modification of Type 1 Diabetes

Type 1 diabetes mellitus (T1DM) is characterized by the progressive, autoimmune-mediated destruction of β cells. As such, restoring immunoregulation early in the disease course is sought to retain endogenous insulin production. Nevertheless, in the more than 100 years since the discovery of insulin, treatment of T1DM has focused primarily on hormone replacement and glucose monitoring. That said, immunotherapies are widely used to interdict autoimmune and autoinflammatory diseases and are emerging as potential therapeutics seeking the preservation of β-cell function among those with T1DM. In the past 4 decades of diabetes research, several immunomodulatory therapies have been explored, culminating with the US Food and Drug Administration approval of teplizumab to delay stage 3 (clinical) onset of T1DM. Clinical trials seeking to prevent or reverse T1DM by repurposing immunotherapies approved for other autoimmune conditions and by exploring new therapeutics are ongoing. Collectively, these efforts have the potential to transform the future of diabetes care. We encapsulate the past 40 years of immunotherapy trials, take stock of our successes and failures, and chart paths forward in this new age of clinically available immune therapies for T1DM.

Chimeric anti-HLA antibody receptor engineered human regulatory T cells suppress alloantigen-specific B cells from pre-sensitized transplant recipients

Organ transplantation is a lifesaving procedure, with 50,000 transplants happening every year in the United States. However, many patients harbor antibodies and B cells directed against allogeneic human leukocyte antigen (HLA) molecules, notably HLA-A2, greatly decreasing their likelihood of receiving a compatible organ. Moreover, antibody-mediated rejection is a significant contributor to chronic transplant rejection. Current strategies to desensitize patients non- specifically target circulating antibodies and B cells, resulting in poor efficacy and complications. Regulatory T cells (Tregs) are immune cells dedicated to suppressing specific immune responses by interacting with both innate and adaptive immune cells. Here, we genetically modified human Tregs with a chimeric anti-HLA antibody receptor (CHAR) consisting of an extracellular HLA-A2 protein fused to a CD28-CD3zeta intracellular signaling domain, driving Treg activation upon recognition of anti-HLA-A2 antibodies on the surface of alloreactive B cells. We find that HLA-A2 CHAR Tregs get activated specifically by anti-HLA-A2 antibody-producing cells. Of note, HLA-A2 CHAR activation does not negatively affect Treg stability, as measured by expression of the Treg lineage transcription factors FOXP3 and HELIOS. Interestingly, HLA-A2 CHAR Tregs are not cytotoxic towards anti-HLA-A2 antibody-producing cells, unlike HLA-A2 CHAR modified conventional CD4 + T cells. Importantly, HLA-A2 CHAR Tregs recognize and significantly suppress high affinity IgG antibody production by B cells from HLA-A2 sensitized patients. Altogether, our results provide proof-of-concept of a new strategy to specifically inhibit alloreactive B cells to desensitize transplant recipients.

Cell therapies for immune-mediated disorders

Immune-mediated disorders are a broad range of diseases, arising as consequence of immune defects, exaggerated/misguided immune response or a mixture of both conditions. Their frequency is on a rise in the developed societies and they pose a significant challenge for diagnosis and treatment. Traditional pharmacological, monoclonal antibody-based or polyclonal antibody replacement-based therapies aiming at modulation of the immune responses give very often dissatisfactory results and/or are burdened with unacceptable adverse effects. In recent years, a new group of treatment modalities has emerged, utilizing cells as living drugs, especially with the use of the up-to-date genetic engineering. These modern cellular therapies are designed to offer a high potential for more targeted, safe, durable, and personalized treatment options. This work briefly reviews the latest advances in the treatment of immune-mediated disorders, mainly those related to exaggeration of the immune response, with such cellular therapies as hematopoietic stem cells (HSCs), mesenchymal stromal cells (MSCs), regulatory T cells (Tregs), chimeric antigen receptor (CAR) T cells and others. We highlight the main features of these therapies as new treatment options for taming the dysregulated immune system. Undoubtfully, in near future such therapies can provide lasting remissions in a range of immune-mediated disorders with reduced treatment burden and improved quality of life for the patients.

Application and Progression of Single-Cell RNA Sequencing in Diabetes Mellitus and Diabetes Complications

Diabetes is a systemic metabolic disorder primarily caused by insulin deficiency and insulin resistance, leading to chronic hyperglycemia. Prolonged diabetes can result in metabolic damage to multiple organs, including the heart, brain, liver, muscles, and adipose tissue, thereby causing various chronic fatal complications such as diabetic retinopathy, diabetic cardiomyopathy, and diabetic nephropathy. Single-cell RNA sequencing (scRNA-seq) has emerged as a valuable tool for investigating the cell diversity and pathogenesis of diabetes and identifying potential therapeutic targets in diabetes or diabetes complications. This review provides a comprehensive overview of recent applications of scRNA-seq in diabetes-related researches and highlights novel biomarkers and immunotherapy targets with cell-type information for diabetes and its associated complications.

T-regulatory cells for the treatment of autoimmune diseases

Autoimmune diseases result from imbalances in the immune system and disturbances in the mechanisms of immune tolerance. T-regulatory cells (Treg) are key factors in the formation of immune tolerance. Tregs modulate immune responses and repair processes, controlling the innate and adaptive immune system. The use of Tregs in the treatment of autoimmune diseases began with the manipulation of endogenous Tregs using immunomodulatory drugs. Then, a method of adoptive transfer of Tregs grown in vitro was developed. Adoptive transfer of Tregs includes polyclonal Tregs with non-specific effects and antigen-specific Tregs in the form of CAR-Treg and TCR-Treg. This review discusses non-specific and antigen-specific approaches to the use of Tregs, their advantages, disadvantages, gaps in development, and future prospects.

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.

Harnessing the biology of regulatory T cells to treat disease

Regulatory T (Treg) cells are a suppressive subset of CD4+ T cells that maintain immune homeostasis and restrain inflammation. Three decades after their discovery, the promise of strategies to harness Treg cells for therapy has never been stronger. Multiple clinical trials seeking to enhance endogenous Treg cells or deliver them as a cell-based therapy have been performed and hint at signs of success, as well as to important limitations and unanswered questions. Strategies to deplete Treg cells in cancer are also in active clinical testing. Furthermore, multi-dimensional methods to interrogate the biology of Treg cells are leading to a refined understanding of Treg cell biology and new approaches to harness tissue-specific functions for therapy. A new generation of Treg cell clinical trials is now being fuelled by advances in nanomedicine and synthetic biology, seeking more precise ways to tailor Treg cell function. This Review will discuss recent advances in our understanding of human Treg cell biology, with a focus on mechanisms of action and strategies to assess outcomes of Treg cell-targeted therapies. It highlights results from recent clinical trials aiming to enhance or inhibit Treg cell activity in a variety of diseases, including allergy, transplantation, autoimmunity and cancer, and discusses ongoing strategies to refine these approaches.

Regulatory cell therapy for kidney transplantation and autoimmune kidney diseases

Regulatory cell therapies, including regulatory T cells and mesenchymal stromal cells, have shown promise in early clinical trials for reducing immunosuppression burden in transplantation. While regulatory cell therapies may also offer potential for treating autoimmune kidney diseases, data remains sparse, limited mainly to preclinical studies. This review synthesises current literature on the application of regulatory cell therapies in these fields, highlighting the safety and efficacy shown in existing clinical trials. We discuss the need for further clinical validation, optimisation of clinical and immune monitoring protocols, and the challenges of manufacturing and quality control under Good Manufacturing Practice conditions, particularly for investigator-led trials. Additionally, we explore the potential for expanding clinical indications and the unique challenges posed in paediatric applications. Future directions include scaling up production, refining protocols to ensure consistent quality across manufacturing sites, and extending applications to other immune-mediated diseases.

Exercise, autoimmune diseases and T-regulatory cells

Diverse forms of physical activities contribute to improvement of autoimmune diseases and may prevent disease burst. T regulatory cells (Tregs) maintain tolerance in autoimmune condition. Physical activity is one of the key factors causing enhancement of Tregs number and functions, keeping homeostatic state by its secrotome. Muscles secrete myokines like IL-6, PGC1α (PPARγ coactivator-1 α), myostatin, transforming growth factor β (TGF-β) superfamily), IL-15, brain derived neurotrophic factor (BDNF) and others. The current concept points to the role of exercise in induction of highly functional and stable muscle Treg phenotype. The residing-Tregs require IL6Rα signaling to control muscle function and regeneration. Skeletal muscle Tregs IL-6Rα is a key target for muscle-Tregs cross-talk. Thus, interplay between the Tregs-skeletal muscle, following exercise, contribute to the balance of immune tolerance and autoimmunity. The cargo delivery, in the local environment and periphery, is performed by extracellular vesicles (EVs) secreted by muscle and Tregs, which deliver proteins, lipids and miRNA during persistent exercise protocols. It has been suggested that this ensemble induce protection against autoimmune diseases.

Human OX40L-CAR-Tregs target activated antigen-presenting cells and control T cell alloreactivity

Regulatory T cells (Tregs) make major contributions to immune homeostasis. Because Treg dysfunction can lead to both allo- and autoimmunity, there is interest in correcting these disorders through Treg adoptive transfer. Two of the central challenges in clinically deploying Treg cellular therapies are ensuring phenotypic stability and maximizing potency. Here, we describe an approach to address both issues through the creation of OX40 ligand (OX40L)-specific chimeric antigen receptor (CAR)-Tregs under the control of a synthetic forkhead box P3 (FOXP3) promoter. The creation of these CAR-Tregs enabled selective Treg stimulation by engagement of OX40L, a key activation antigen in alloimmunity, including both graft-versus-host disease and solid organ transplant rejection, and autoimmunity, including rheumatoid arthritis, systemic sclerosis, and systemic lupus erythematosus. We demonstrated that OX40L-CAR-Tregs were robustly activated in the presence of OX40L-expressing cells, leading to up-regulation of Treg suppressive proteins without induction of proinflammatory cytokine production. Compared with control Tregs, OX40L-CAR-Tregs more potently suppressed alloreactive T cell proliferation in vitro and were directly inhibitory toward activated monocyte-derived dendritic cells (DCs). We identified trogocytosis as one of the central mechanisms by which these CAR-Tregs effectively decrease extracellular display of OX40L, resulting in decreased DC stimulatory capacity. OX40L-CAR-Tregs demonstrated an enhanced ability to control xenogeneic graft-versus-host disease compared with control Tregs without abolishing the graft-versus-leukemia effect. These results suggest that OX40L-CAR-Tregs may have wide applicability as a potent cellular therapy to control both allo- and autoimmune diseases.

Biological function of type 1 regulatory cells and their role in type 1 diabetes

The collapse of immune homeostasis induces type 1 diabetes (T1D). In T1D, uncontrolled immune attacks against islet β cells reduce insulin secretion, resulting in hyperglycaemia and various complications. Type 1 regulatory (Tr1) cell therapy is a promising approach for the treatment of T1D. Tr1 cells are a subset of regulatory T (Treg) cells that are characterised by high interleukin-10 secretion and forkhead box protein P3 non-expression. Tr1 cells are reduced and have impaired function in patients with T1D. Immunotherapy is used to treat various diseases, and Treg cells have been applied to treat T1D in animal models and clinical trials. However, the safety and efficacy of Tr1 cells in treating diabetes and other diseases remain unclear. In this review, we aim to investigate the identification and biological function of Tr1 cells and related studies on immune diseases; additionally, we discuss the feasibility, limitations, and possible solutions of Tr1 cell therapy in T1D. This review shows that T1D is caused by an immune imbalance where defective Tr1 cells fail to control effector T cells, leading to the destruction of islet β cells. However, Tr1 cell therapy is safe and effective for other immune diseases, suggesting its potential for treating T1D.

Regulatory T Cell Dysfunction in Autoimmune Diseases

Regulatory T cells (Tregs), a suppressive subpopulation of T cells, are potent mediators of peripheral tolerance, responsible for immune homeostasis. Many autoimmune diseases exhibit disruptions in Treg function or quantity, resulting in an imbalance between protective and pathogenic immune cells. Selective expansion or manipulation of Tregs is a promising therapeutic approach for autoimmune diseases. However, the extensive diversity of Treg subpopulations and the multiple approaches used for Treg identification leads to high complexity, making it difficult to develop a successful treatment capable of modulating Tregs. In this review, we describe the suppressive mechanisms, subpopulations, classification, and identification methodology for Tregs, and their role in the pathogenesis of autoimmune diseases.