Reversal of type 1 diabetes by a new MHC II-peptide chimera: “Single-epitope-mediated suppression” to stabilize a polyclonal autoimmune T-cell process

Epitope-based precision immunotherapy of Type 1 diabetes

Antigen-specific immunotherapies (ASITs) address important clinical needs in treating autoimmune diseases. However, Type 1 diabetes is a heterogeneous disease wherein patient characteristics influence responsiveness to ASITs. Targeting not only disease-relevant T cell populations, but also specific groups of patients using precision medicine is a new goal toward achieving effective treatment. HLA-restricted peptides provide advantages over protein as antigens, however, methods for profiling antigen-specific T cells need to improve in sensitivity, depth, and throughput to facilitate epitope selection. Delivery approaches are highly diverse, illustrating the many ways relevant antigen-presenting cell populations and anatomical locations can be targeted for tolerance induction. The role of persistence of antigen presentation in promoting durable antigen-specific tolerance requires further investigation. Based on the outcome of ASIT trials, the field is moving toward using patient-specific variations to improve efficacy, but challenges still lie on the path to delivering more effective and safer treatment to the T1D patient population.

Biologia Futura: Emerging antigen-specific therapies for autoimmune diseases

Autoimmune diseases are caused by breaking the central and/or peripheral tolerance against self, leading to uncontrolled immune response to autoantigens. The incidences of autoimmune diseases have increased significantly worldwide over the last decades; nearly 5% of the world's population is affected. The current treatments aim to reduce pain and inflammation to prevent organ damage and have a general immunosuppressive effect, but they cannot cure the disease. There is a huge unmet need for autoantigen-specific therapy, without affecting the immune response against pathogens. This goal can be achieved by targeting autoantigen-specific T or B cells and by restoring self-tolerance by inducing tolerogenic antigen-presenting cells (APC) and the development of regulatory T (Treg) cells, for example, by using autoantigenic peptides bound to nanoparticles. Transferring in vitro manipulated autologous tolerogenic APC or autologous autoantigen-specific Treg cells to patients is the promising approach to develop cellular therapeutics. Most recently, chimeric autoantibody receptor T cells have been designed to specifically deplete autoreactive B cells. Limitations of these novel autoantigen-specific therapies will also be discussed.

T cell receptor revision and immune repertoire changes in autoimmune diseases

Autoimmune disease (AID) is a condition in which the immune system breaks down and starts to attack the body. Some common AIDs include systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes mellitus and so forth. The changes in T-cell receptor (TCR) repertoire have been found in several autoimmune diseases, and may be responsible for the breakdown of peripheral immune tolerance. In this review, we discussed the processes of TCR revision in peripheral immune environment, the changes in TCR repertoire that occurred in various AIDs, and the specifically expanded T cell clones. We hope our discussion can provide insights for the future studies, helping with the discovery of disease biomarkers and expanding the strategies of immune-targeted therapy. HighlightsRestricted TCR repertoire and biased TCR-usage are found in a variety of AIDs.TCR repertoire shows tissue specificity in a variety of AID diseases.The relationship between TCR repertoire diversity and disease activity is still controversial in AIDs.Dominant TCR clonotypes may help to discover new disease biomarkers and expand the strategies of immune-targeted therapy.

Induction of Antigen-Specific Tolerance in T Cell Mediated Diseases

The development of novel approaches to control unwanted immune responses represents an ambitious goal in the management of a number of clinical conditions, including autoimmunity, autoinflammatory diseases, allergies and replacement therapies, in which the T cell response to self or non-harmful antigens threatens the physiological function of tissues and organs. Current treatments for these conditions rely on the use of non-specific immunosuppressive agents and supportive therapies, which may efficiently dampen inflammation and compensate for organ dysfunction, but they require lifelong treatments not devoid of side effects. These limitations induced researchers to undertake the development of definitive and specific solutions to these disorders: the underlying principle of the novel approaches relies on the idea that empowering the tolerogenic arm of the immune system would restore the immune homeostasis and control the disease. Researchers effort resulted in the development of cell-free strategies, including gene vaccination, protein-based approaches and nanoparticles, and an increasing number of clinical trials tested the ability of adoptive transfer of regulatory cells, including T and myeloid cells. Here we will provide an overview of the most promising approaches currently under development, and we will discuss their potential advantages and limitations. The field is teaching us that the success of these strategies depends primarily on our ability to dampen antigen-specific responses without impairing protective immunity, and to manipulate directly or indirectly the immunomodulatory properties of antigen presenting cells, the ultimate in vivo mediators of tolerance.

Reversal of Hyperglycemia and Suppression of Type 1 Diabetes in the NOD Mouse with Apoptotic DNA Immunotherapy™ (ADi™), ADi-100

The antigen-specific apoptotic DNA immunotherapeutic, ADi-100, is designed to suppress type 1 diabetes and consists of two DNA plasmids encoding genetic sequences of the apoptosis-inducing molecule, BAX, and the secreted form of the autoantigen, glutamic acid decarboxylase 65, that is CpG hyper-methylated to avoid inflammatory signaling (msGAD55). Upon a four-day treatment with ADi-100 of young female non-obese diabetic (NOD) mice, the frequency of various tolerogenic dendritic cell populations increased in draining lymph nodes; these cells lost the capacity to stimulate glutamic acid decarboxylase (GAD)-specific CD4⁺ T lymphocytes and were associated with the previously demonstrated enhancement of GAD-specific regulatory T cells. The efficacy of two ADi-100 formulations containing different proportions of BAX and msGAD55, 1:4 (10/40 µg) and 1:2 (17/33 µg), was evaluated in mildly hyperglycemic pre-diabetic NOD female mice. Both formulations suppressed the incidence of diabetes by 80% in an antigen-specific manner, while all untreated mice developed diabetes. However, treatment of pre-diabetic mice with significantly higher hyperglycemia, denoting progressive disease, showed that ADi-100 1:2 strongly suppressed diabetes incidence by 80% whereas the ADi-100 1:4 was less effective (50%). As an antigen-specific monotherapy, ADi-100 is highly efficacious in reversing elevated hyperglycemia to prevent diabetes, in which increasing apoptosis-inducing BAX content is a promising immune tolerance feature.

Antigen-specific therapeutic approaches for autoimmunity

The main function of the immune system in health is to protect the host from infection by microbes and parasites. Because immune responses to nonself bear the risk of unleashing accidental immunity against self, evolution has endowed the immune system with central and peripheral mechanisms of tolerance, including regulatory T and B cells. Although the past two decades have witnessed the successful clinical translation of a whole host of novel therapies for the treatment of chronic inflammation, the development of antigen-based approaches capable of selectively blunting autoimmune inflammation without impairing normal immunity has remained elusive. Earlier autoantigen-specific approaches employing peptides or whole antigens have evolved into strategies that seek to preferentially deliver these molecules to autoreactive T cells either indirectly, via antigen-presenting cells, or directly, via major histocompatibility complex molecules, in ways intended to promote clonal deletion and/or immunoregulation. The disease specificity, mechanistic underpinnings, developability and translational potential of many of these strategies remain unclear.

WITHDRAWN: T cell receptor revision and immune repertoire changes in autoimmune diseases

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Treatment of T1D via optimized expansion of antigen-specific Tregs induced by IL-2/anti-IL-2 monoclonal antibody complexes and peptide/MHC tetramers

Type 1 diabetes can be overcome by regulatory T cells (Treg) in NOD mice yet an efficient method to generate and maintain antigen-specific Treg is difficult to come by. Here, we devised a combination therapy of peptide/MHC tetramers and IL-2/anti-IL-2 monoclonal antibody complexes to generate antigen-specific Treg and maintain them over extended time periods. We first optimized treatment protocols conceived to obtain an improved islet-specific Treg/effector T cell ratio that led to the in vivo expansion and activation of these Treg as well as to an improved suppressor function. Optimized protocols were applied to treatment for testing diabetes prevention in NOD mice as well as in an accelerated T cell transfer model of T1D. The combined treatment led to robust protection against diabetes, and in the NOD model, to a close to complete prevention of insulitis. Treatment was accompanied with increased secretion of IL-10, detectable in total splenocytes and in Foxp3⁻ CD4 T cells. Our data suggest that a dual protection mechanism takes place by the collaboration of Foxp3⁺ and Foxp3⁻ regulatory cells. We conclude that antigen-specific Treg are an important target to improve current clinical interventions against this disease.

The importance of the Non Obese Diabetic (NOD) mouse model in autoimmune diabetes

Type 1 Diabetes (T1D) is an autoimmune disease characterized by the pancreatic infiltration of immune cells resulting in T cell-mediated destruction of the insulin-producing beta cells. The successes of the Non-Obese Diabetic (NOD) mouse model have come in multiple forms including identifying key genetic and environmental risk factors e.g. Idd loci and effects of microorganisms including the gut microbiota, respectively, and how they may contribute to disease susceptibility and pathogenesis. Furthermore, the NOD model also provides insights into the roles of the innate immune cells as well as the B cells in contributing to the T cell-mediated disease. Unlike many autoimmune disease models, the NOD mouse develops spontaneous disease and has many similarities to human T1D. Through exploiting these similarities many targets have been identified for immune-intervention strategies. Although many of these immunotherapies did not have a significant impact on human T1D, they have been shown to be effective in the NOD mouse in early stage disease, which is not equivalent to trials in newly-diagnosed patients with diabetes. However, the continued development of humanized NOD mice would enable further clinical developments, bringing T1D research to a new translational level. Therefore, it is the aim of this review to discuss the importance of the NOD model in identifying the roles of the innate immune system and the interaction with the gut microbiota in modifying diabetes susceptibility. In addition, the role of the B cells will also be discussed with new insights gained through B cell depletion experiments and the impact on translational developments. Finally, this review will also discuss the future of the NOD mouse and the development of humanized NOD mice, providing novel insights into human T1D.

HLA-DR*0401 expression in the NOD mice prevents the development of autoimmune diabetes by multiple alterations in the T-cell compartment

Several human HLA alleles have been found associated with type 1 diabetes (T1D), but their precise role is not clearly defined. Herein, we report that a human MHC class II (HLA-DR*0401) allele transgene that has been expressed into NOD (H-2(g7)I-E(null)) mice prone to T1D rendered the mice resistant to the disease. T1D resistance occurred in the context of multi-point T-cell alterations such as: (i) skewed CD4/CD8 T-cell ratio, (ii) decreased size of CD4(+)CD44(high) T memory pool, (iii) aberrant TCR Vβ repertoire, (iv) increased neonatal number of Foxp3(+) and TR-1(+) regulatory cells, and (v) reduced IFN-γ inflammatory response vs. enhanced IL-10 suppressogenic response of T-cells upon polyclonal and antigen-specific stimulation. The T-cells from NOD/DR4 Tg mice were unable to induce or suppress diabetes in NOD/RAG deficient mice. This study describes a multifaceted regulatory function of the HLA-DR*0401 allele strongly associated with the lack of T1D development in NOD mice.

Divergent cerebrospinal fluid cytokine network induced by non-viral and different viral infections on the central nervous system

Background

Meningoencephalitis is one of the most common disorders of the central nervous system (CNS) worldwide. Viral meningoencephalitis differs from bacterial meningitis in several aspects. In some developing countries, bacterial meningitis has appropriate clinical management and chemotherapy is available. Virus-associated and virus not detected meningoencephalitis are treatable, however, they may cause death in a few cases. The knowledge of how mediators of inflammation can induce disease would contribute for the design of affordable therapeutic strategies, as well as to the diagnosis of virus not detected and viral meningoencephalitis. Cytokine-induced inflammation to CNS requires several factors that are not fully understood yet.

Methods

Considering this, several cytokines were measured in the cerebrospinal fluid (CSF) of patients with undiagnosed and viral meningoencephalitis, and these were correlated with cellularity in the CSF.

Results

The results demonstrate that an altered biochemical profile alongside increased cellularity in the cerebrospinal fluid is a feature of patients with meningoencephalitis that are not associated with the detection of virus in the CNS (P < 0.05). Moreover, HIV-positive patients (n = 10) that evolve with meningoencephalitis display a distinct biochemical/cytological profile (P < 0.05) in the cerebrospinal fluid. Meningoencephalitis brings about a prominent intrathecal cytokine storm regardless of the detection of virus as presumable etiological agent. In the case of Enterovirus infection (n = 13), meningoencephalitis elicits robust intrathecal pro-inflammatory cytokine pattern and elevated cellularity when compared to herpesvirus (n = 15) and Arbovirus (n = 5) viral infections (P < 0.05).

Conclusion

Differences in the cytokine profile of the CSF may be unique if distinct, viral or presumably non-viral pathways initially trigger the inflammatory response in the CNS.

Taming the TCR: antigen-specific immunotherapeutic agents for autoimmune diseases

Current treatments for autoimmune diseases are typically non-specific anti-inflammatory agents that affect not only the autoreactive cells but also the parts of the immune system that are required to maintain health. There is a need for the development of antigen-specific therapeutic agents that can effectively prevent the autoimmune attack while leaving the rest of the immune system functioning as normal. The simplest way to achieve this is using the autoantigen itself as a tolerizing agent; however, there is some risk involved with administering a potentially pathogenic antigen. In this review, we focus instead on the development and use of modified T cell receptor (TCR) ligands, in which the peptide ligand is modified to change the response by the T cell from a disease inducing to a protective response, and still retain the antigen-specificity necessary to target the autoreactive T cells. We review the use of modified TCR ligands as therapeutic agents in animal models of autoimmunity and in human autoimmune disease, and finally consider how they need to be improved in order to use them effectively in patients with autoimmune disease.

The rise, fall, and resurgence of immunotherapy in type 1 diabetes

Despite considerable effort to halt or delay destruction of β-cells in autoimmune type 1 diabetes (T1D), success remains elusive. Over the last decade, we have seen a proliferation of knowledge on the pathogenesis of T1D that emerged from studies performed in non-obese diabetic (NOD) mice. However, while results of these preclinical studies appeared to hold great promise and boosted patients' hopes, none of these approaches, once tested in clinical settings, induced remission of autoimmune diabetes in individuals with T1D. The primary obstacles to translation reside in the differences between the human and murine autoimmune responses and in the contribution of many environmental factors associated with the onset of disease. Moreover, inaccurate dosing as well as inappropriate timing and uncertain length of drug exposure have played a central role in the negative outcomes of such therapeutic interventions. In this review, we summarize the most important approaches tested thus far in T1D, beginning with the most successful preclinical studies in NOD mice and ending with the latest disappointing clinical trials in humans. Finally, we highlight recent stem cell-based trials, for which expectations in the scientific community and among individuals with T1D are high.

Long-term silencing of autoimmune diabetes and improved life expectancy by a soluble pHLA-DR4 chimera in a newly-humanized NOD/DR4/B7 mouse

Several human MHC class II (HLA) molecules are strongly associated with high incidence of autoimmune diseases including type 1 diabetes (T1D). The HLA-humanized mice may thus represent valuable tools to test HLA-based vaccines and therapeutics for human autoimmune diseases. Herein, we have tested the therapeutic potential of a soluble HLA-DR4-GAD65 271-280 (hu DEF-GAD65) chimera of human use in a newly-generated NOD/DR4/B7 double transgenic (dTg) mouse that develops spontaneously an accelerated T1D regardless the gender. The NOD/DR4/B7 dTg mice generated by a two-step crossing protocol express the HLA-DR*0401 molecules on 20% of antigen presenting cells, the human B7 molecules in pancreas, and HLA-DR4/GAD65-specific T-cells in the blood. Some 75% of pre-diabetic NOD/DR4/B7 dTg mice treated with hu DEF-GAD65 chimera remained euglycemic and showed a stabilized pancreatic insulitis 6 months after treatment. The 25% non responders developing hyperglycemia survived 3-4 months longer than their untreated littermates. T1D prevention by this reagent occurred by a Th2/TR-1 polarization in the pancreas. This study strongly suggests that the use of soluble pHLA reagents to suppress/stabilize the T1D progression and to extend the life expectancy in the absence of side effects is an efficient and safe therapeutic approach.

Antigen-specific therapeutic approaches in Type 1 diabetes

Development of strategies capable of specifically curbing pathogenic autoimmune responses in a disease- and organ-specific manner without impairing foreign or tumor antigen-specific immune responses represents a long sought-after goal in autoimmune disease research. Unfortunately, our current understanding of the intricate details of the different autoimmune diseases that affect mankind, including type 1 diabetes, is rudimentary. As a result, progress in the development of the so-called "antigen-specific" therapies for autoimmunity has been slow and fraught with limitations that interfere with bench-to-bedside translation. Absent or incomplete understanding of mechanisms of action and lack of adequate immunological biomarkers, for example, preclude the rational design of effective drug development programs. Here, we provide an overview of antigen-specific approaches that have been tested in preclinical models of T1D and, in some cases, human subjects. The evidence suggests that effective translation of these approaches through clinical trials and into patients will continue to meet with failure unless detailed mechanisms of action at the level of the organism are defined.

Dimeric MHC-peptides inserted into an immunoglobulin scaffold as new immunotherapeutic agents

The interactions of the T cell receptor (TCR) with cognate MHC-peptide and co-stimulatory molecules expressed at surface of antigen presenting cells (APC) leads to activation or tolerance of T cells. The development of molecular biological tools allowed for the preparation of soluble MHC-peptide molecules as surrogate for the APC. A decade ago a monomeric class II MHC molecule in which the peptide was covalently linked to β-chain of class II molecule was generated. This type of molecule had a low-binding affinity and did not cause the multimerization of TCR. The requirement of multimerization of TCR led to development of a new class of reagents, chimeric peptides covalently linked to MHC that was dimerized via Fc fragment of an immunoglobulin and linked to 3' end of the β-chain of MHC class II molecule. These soluble dimerized MHC-peptide chimeric molecules display high affinity for the TCR and caused multimerization of TCR without processing by an APC. Because dimeric molecules are devoid of co-stimulatory molecules interacting with CD28, a second signal, they induce anergy rather the activation of T cells. In this review, we compare the human and murine dimerized MHC class II-peptides and their effect on CD4(+) T cells, particularly the generation of T regulatory cells, which make these chimeric molecules an appealing approach for the treatment of autoimmune diseases.

Peptide-MHC-based nanovaccines for the treatment of autoimmunity: a "one size fits all" approach?

Nanotechnology offers enormous potential in drug delivery and in vivo imaging. Nanoparticles (NPs), for example, are being extensively tested as scaffolds to deliver anti-cancer therapeutics or imaging tags. Our recent work, discussed herein, indicates that an opportunity exists to use NPs to deliver ligands for, and trigger, cognate receptors on T lymphocytes as a way to induce therapeutic immune responses in vivo. Specifically, systemic delivery of NPs coated with Type 1 diabetes (T1D)-relevant peptide-major histocompatibility complex molecules triggered the expansion of cognate memory autoregulatory (disease-suppressing) T cells, suppressed the progression of autoimmune attack against insulin-producing beta cells, and restored glucose homeostasis. This therapeutic avenue exploits a new paradigm in the progression of chronic autoimmune responses that enables the rational design of disease-specific "nanovaccines" capable of blunting autoimmunity without impairing systemic immunity, a long sought-after goal in the therapy of these disorders. Here, we discuss the research paths that led to the discovery of this therapeutic avenue and highlight the features that make it an attractive approach for the treatment, in an antigen-specific manner, of a whole host of autoimmune diseases.