T-cell responses to hybrid insulin peptides prior to type 1 diabetes development.

T-cell responses to posttranslationally modified self-antigens are associated with many autoimmune disorders. In type 1 diabetes, hybrid insulin peptides (HIPs) are implicated in the T-cell-mediated destruction of insulin-producing ß-cells within pancreatic islets. The natural history of the disease is such that it allows for the study of T-cell reactivity prior to the onset of clinical symptoms. We hypothesized that CD4 T-cell responses to posttranslationally modified islet peptides precedes diabetes onset. In a cohort of genetically at-risk individuals, we measured longitudinal T-cell responses to native insulin and hybrid insulin peptides. Both proinflammatory (interferon-γ) and antiinflammatory (interluekin-10) cytokine responses to HIPs were more robust than those to native peptides, and the ratio of such responses oscillated between pro- and antiinflammatory over time. However, individuals who developed islet autoantibodies or progressed to clinical type 1 diabetes had predominantly inflammatory T-cell responses to HIPs. Additionally, several HIP T-cell responses correlated to worsening measurements of blood glucose, highlighting the relevance of T-cell responses to posttranslationally modified peptides prior to autoimmune disease development.

Human islet T cells are highly reactive to preproinsulin in type 1 diabetes.

Cytotoxic CD8 T lymphocytes play a central role in the tissue destruction of many autoimmune disorders. In type 1 diabetes (T1D), insulin and its precursor preproinsulin are major self-antigens targeted by T cells. We comprehensively examined preproinsulin specificity of CD8 T cells obtained from pancreatic islets of organ donors with and without T1D and identified epitopes throughout the entire preproinsulin protein and defective ribosomal products derived from preproinsulin messenger RNA. The frequency of preproinsulin-reactive T cells was significantly higher in T1D donors than nondiabetic donors and also differed by individual T1D donor, ranging from 3 to over 40%, with higher frequencies in T1D organ donors with HLA-A*02:01. Only T cells reactive to preproinsulin-related peptides isolated from T1D donors demonstrated potent autoreactivity. Reactivity to similar regions of preproinsulin was also observed in peripheral blood of a separate cohort of new-onset T1D patients. These findings have important implications for designing antigen-specific immunotherapies and identifying individuals that may benefit from such interventions.

Self-Antigens Targeted by Regulatory T Cells in Type 1 Diabetes.

While progress has been made toward understanding mechanisms that lead to the development of autoimmunity, there is less knowledge regarding protective mechanisms from developing such diseases. For example, in type 1 diabetes (T1D), the immune-mediated form of diabetes, the role of pathogenic T cells in the destruction of pancreatic islets is well characterized, but immune-mediated mechanisms that contribute to T1D protection have not been fully elucidated. One potential protective mechanism includes the suppression of immune responses by regulatory CD4 T cells (Tregs) that recognize self-peptides from islets presented by human leukocyte antigen (HLA) class II molecules. In this review, we summarize what is known about the antigenic self-peptides recognized by Tregs in the context of T1D.

Screening children for type 1 diabetes-associated antibodies at community health fairs.

OBJECTIVE: The incidence of type 1 diabetes (T1D) is increasing, most notably in young children and in racial and ethnic minorities. Historically, screening for risk with T1D-associated antibodies has been limited to those with a family history, while up to 90% of newly diagnosed patients lack such a family history. To address the needs to screen diverse ethnic groups in the general population, we screened children for T1D-associated antibodies in the Denver, Colorado metro area at community health fairs. METHODS: Children attending health fairs from 2015 to 2018 were offered free T1D screening by measuring the four prototypical T1D-associated antibodies. A finger stick capillary puncture was performed to collect blood spots on filter paper. Dried blood spots (DBSs) were eluted and antibodies were measured using fluid-phase radio-binding assays. RESULTS: At 39 health fairs, children were educated on the signs and symptoms of diabetes, and screened for T1D-associated antibodies (n = 478), which represented 90% of those that attended. Median age was 9.0 years (range of 1-18) with diverse ethnic backgrounds: 37% Hispanic, 31% Caucasian, 20% African American, and 12% other. Nine children screened positive for antibodies, single n = 8 and multiple n = 1, and confirmation with serum samples showed excellent correlation to the measurements from DBSs for antibodies directed against GAD, IA-2, and ZnT8 (P < .01 for each). CONCLUSIONS: Screening for T1D risk at community health fairs using DBSs on filter paper is feasible and provides an avenue to screen children from ethnically diverse backgrounds.

Deciphering the Pathogenesis of Human Type 1 Diabetes (T1D) by Interrogating T Cells from the "Scene of the Crime".

PURPOSE OF REVIEW: Autoimmune-mediated destruction of insulin-producing ß-cells within the pancreas results in type 1 diabetes (T1D), which is not yet preventable or curable. Previously, our understanding of the ß-cell specific T cell repertoire was based on studies of autoreactive T cell responses in the peripheral blood of patients at risk for, or with, T1D; more recently, investigations have included immunohistochemical analysis of some T cell specificities in the pancreas from organ donors with T1D. Now, we are able to examine live, islet-infiltrating T cells from donors with T1D. RECENT FINDINGS: Analysis of the T cell repertoire isolated directly from the pancreatic islets of donors with T1D revealed pro-inflammatory T cells with targets of known autoantigens, including proinsulin and glutamic acid decarboxylase, as well as modified autoantigens. We have assayed the islet-infiltrating T cell repertoire for autoreactivity and function directly from the inflamed islets of T1D organ donors. Design of durable treatments for prevention of or therapy for T1D requires understanding this repertoire.

Immune Intervention and Preservation of Pancreatic Beta Cell Function in Type 1 Diabetes.

Type 1 diabetes (T1D) results from the immune-mediated destruction of insulin-producing ß cells located within the pancreatic islets of Langerhans. The autoimmune process leads to a deficiency in insulin production and resultant hyperglycemia requiring lifelong treatment with insulin administration. T1D continues to dramatically increase in incidence, especially in young children. Substantial knowledge surrounding human disease pathogenesis exists, such that T1D is now predictable with the measurement of antibodies in the peripheral blood directed against insulin and other ß cell proteins. With the ability to predict, it naturally follows that T1D should be preventable. As such, over the last two decades, numerous well-controlled clinical trials have been completed attempting to prevent diabetes onset or maintain residual ß cell function after clinical onset, all providing relatively disappointing results. Here, we review the T1D prevention efforts, the current landscape of clinical therapies, and end with a discussion regarding the future outlook for preventing T1D.

New approaches for predicting T cell-mediated drug reactions: A role for inducible and potentially preventable autoimmunity.

Adverse drug reactions (ADRs) are commonplace and occur when a drug binds to its intended pharmacologic target (type A ADR) or an unintended target (type B ADR). Immunologically mediated type B ADRs, such as drug hypersensitivity syndrome, drug reaction with eosinophilia and systemic symptoms syndrome, and Stevens-Johnson syndrome/toxic epidermal necrolysis, can be severe and result in a diverse set of clinical manifestations that include fever and rash, as well as multiple organ failure (liver, kidney, lungs, and/or heart) in the case of drug hypersensitivity syndrome. There is increasing evidence that specific HLA alleles influence the risk of drug reactions. Several features of T cell-mediated ADRs are strikingly similar to those displayed by patients with autoimmune diseases like type I diabetes, such as strong HLA association, organ-specific adaptive immune responses, viral involvement, and activation of innate immunity. There is a need to better predict patient populations at risk for immunologically mediated type B ADRs. Because methods to predict type 1 diabetes by using genetic and immunologic biomarkers have been developed to a high level of accuracy (predicting 100% of subjects likely to progress), new research strategies based on these methods might also improve the ability to predict drug hypersensitivity.

Type 1 diabetes.

Over the past decade, knowledge of the pathogenesis and natural history of type 1 diabetes has grown substantially, particularly with regard to disease prediction and heterogeneity, pancreatic pathology, and epidemiology. Technological improvements in insulin pumps and continuous glucose monitors help patients with type 1 diabetes manage the challenge of lifelong insulin administration. Agents that show promise for averting debilitating disease-associated complications have also been identified. However, despite broad organisational, intellectual, and fiscal investments, no means for preventing or curing type 1 diabetes exists, and, globally, the quality of diabetes management remains uneven. This Seminar discusses current progress in epidemiology, pathology, diagnosis, and treatment of type 1 diabetes, and prospects for an improved future for individuals with this disease.

Molecular Interactions Governing Autoantigen Presentation in Type 1 Diabetes.

Type 1 diabetes is a chronic autoimmune disease resulting from T cell-mediated destruction of insulin-producing beta cells within pancreatic islets. Disease incidence has increased significantly in the last two decades, especially in young children. Type 1 diabetes is now predictable in humans with the measurement of serum islet autoantibodies directed against insulin and beta cell proteins. Knowledge regarding the presentation of insulin and islet antigens to T cells has increased dramatically over the last several years. Here, we review the trimolecular complex in diabetes, which consists of a major histocompatibility molecule,self-peptide, and T cell receptor, with a focus on insulin peptide presentation to T cells. With this increased understanding of how antigens are presented to T cells comes the hope for improved therapies for type 1 diabetes prevention.

Immune intervention in type 1 diabetes.

Type 1 diabetes (T1D) is a chronic autoimmune disease that results in the specific immune destruction of insulin producing beta cells. Currently there is no cure for T1D and treatment for the disease consists of lifelong administration of insulin. Immunotherapies aimed at preventing beta cell destruction in T1D patients with residual c-peptide or in individuals developing T1D are being evaluated. Networks of researchers such as TrialNet and the Immune Tolerance Network in the U.S. and similar networks in Europe have been established to evaluate such immunotherapies. This review focuses on immune intervention for the prevention and amelioration of human T1D with a focus on potential immune suppressive, antigen specific and environmental therapies.

Cell-Surface ZnT8 Antibody Prevents and Reverses Autoimmune Diabetes in Mice.

Type 1 diabetes (T1D) is an autoimmune disease in which pathogenic lymphocytes target autoantigens expressed in pancreatic islets, leading to the destruction of insulin-producing ß-cells. Zinc transporter 8 (ZnT8) is a major autoantigen abundantly present on the ß-cell surface. This unique molecular target offers the potential to shield ß-cells against autoimmune attacks in T1D. Our previous work showed that a monoclonal antibody (mAb43) against cell-surface ZnT8 could home in on pancreatic islets and prevent autoantibodies from recognizing ß-cells. This study demonstrates that mAb43 binds to exocytotic sites on the ß-cell surface, masking the antigenic exposure of ZnT8 and insulin after glucose-stimulated insulin secretion. In vivo administration of mAb43 to NOD mice selectively increased the proportion of regulatory T cells in the islet, resulting in complete and sustained protection against T1D onset as well as reversal of new-onset diabetes. The mAb43-induced self-tolerance was reversible after treatment cessation, and no adverse effects were exhibited during long-term monitoring. Our findings suggest that mAb43 masking of the antigenic exposure of ß-cells suppresses the immunological cascade from B-cell antigen presentation to T cell-mediated ß-cell destruction, providing a novel islet-targeted and antigen-specific immunotherapy to prevent and reverse clinical T1D.

Targeting the trimolecular complex.

Class II major histocompatibility molecules (MHC) confer disease risk for multiple autoimmune disorders including type 1 diabetes. The interaction between the components of the trimolecular complex (CD4(+) T cell receptors, self-peptide, and MHC class II molecules) plays a pivotal role in autoimmune disease pathogenesis. The development of therapies targeting various components of the trimolecular complex for the prevention of type 1 diabetes is actively being pursued. This review focuses on the components of the anti-insulin trimolecular complex, registers of insulin peptide binding to 'diabetogenic' MHC class II molecules, and therapies targeting each component of the trimolecular complex.

Structure-based selection of small molecules to alter allele-specific MHC class II antigen presentation.

Class II major histocompatibility molecules are the primary susceptibility locus for many autoimmune disorders, including type 1 diabetes. Human DQ8 and I-A(g7), in the NOD mouse model of spontaneous autoimmune diabetes, confers diabetes risk by modulating presentation of specific islet peptides in the thymus and periphery. We used an in silico molecular docking program to screen a large "druglike" chemical library to define small molecules capable of occupying specific structural pockets along the I-A(g7) binding groove, with the objective of influencing presentation to T cells of the autoantigen insulin B chain peptide consisting of amino acids 9-23. In this study we show, using both murine and human cells, that small molecules can enhance or inhibit specific TCR signaling in the presence of cognate target peptides, based upon the structural pocket targeted. The influence of compounds on the TCR response was pocket dependent, with pocket 1 and 6 compounds inhibiting responses and molecules directed at pocket 9 enhancing responses to peptide. At nanomolar concentrations, the inhibitory molecules block the insulin B chain peptide consisting of amino acids 9-23, endogenous insulin, and islet-stimulated T cell responses. Glyphosine, a pocket 9 compound, enhances insulin peptide presentation to T cells at concentrations as low as 10 nM, upregulates IL-10 secretion, and prevents diabetes in NOD mice. These studies present a novel method for identifying small molecules capable of both stimulating and inhibiting T cell responses, with potentially therapeutic applications.

Similar Time Course of Humoral Response to SARS-CoV-2 mRNA Vaccines in People With and Without Type 1 Diabetes.

Objective: To assess whether the immunogenicity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines or breakthrough infection rates differ between patients with type 1 diabetes (T1D) and control subjects. Research Design and Methods: A prospective 12-month follow-up of 27 adults with T1D and 89 control subjects who received at least two doses of either the mRNA-1273 or BNT162b2 vaccine. Primary outcomes: total antibodies against the receptor-binding domain and neutralizing antibodies. A multivariate repeated measures model evaluated potential determinants of antibody response. Results: Neither antibody levels nor breakthrough infection rates after vaccination differed in T1D and non-T1D groups. Older age predicted lower antibody levels, whereas SARS-CoV-2 infection or booster vaccine resulted in higher antibody levels in both groups. mRNA-1273 was associated with higher antibody levels than BNT162b2 until 6 months after the first dose. Conclusions: Persons with and without T1D have similar humoral antibody responses to SARS-CoV-2 mRNA vaccines during 12-months of follow-up.

Tracking DNA-based antigen-specific T cell receptors during progression to type 1 diabetes.

T cells targeting self-proteins are important mediators in autoimmune diseases. T cells express unique cell-surface receptors (TCRs) that recognize peptides presented by major histocompatibility molecules. TCRs have been identified from blood and pancreatic islets of individuals with type 1 diabetes (T1D). Here, we tracked ~1700 known antigen-specific TCR sequences, islet antigen or viral reactive, in bulk TCRß sequencing from longitudinal blood DNA samples in at-risk cases who progressed to T1D, age/sex/human leukocyte antigen-matched controls, and a new-onset T1D cohort. Shared and frequent antigen-specific TCRß sequences were identified in all three cohorts, and viral sequences were present across all ages. Islet sequences had different patterns of accumulation based upon antigen specificity in the at-risk cases. Furthermore, 73 islet-antigen TCRß sequences were present in higher frequencies and numbers in T1D samples relative to controls. The total number of these disease-associated TCRß sequences inversely correlated with age at clinical diagnosis, indicating the potential to use disease-relevant TCR sequences as biomarkers in autoimmune disorders.

Analysis of Human Leukocyte Antigen DR Alleles, Immune-Related Adverse Events, and Survival Associated With Immune Checkpoint Inhibitor Use Among Patients With Advanced Malignant Melanoma.

Importance: Treatment with immune checkpoint inhibitors (ICIs) has increased survival in patients with advanced malignant melanoma but can be associated with a wide range of immune-related adverse events (irAEs). The role of human leukocyte antigen (HLA)-DR alleles in conferring irAE risk has not been well studied. Objective: To evaluate the association between irAEs and treatment response, survival, and the presence of HLA-DR alleles after ICI therapy in advanced melanoma. Design, Setting, and Participants: This case-control study used the patient registry and biobanked samples from the tertiary referral University of Colorado Cancer Center. Specimens and clinical data were collected between January 1, 2010, and December 31, 2021. Patients with advanced (stage III unresectable and stage IV) melanoma who received ICI therapy (n = 132) were included in the analysis. Exposures: Immune checkpoint inhibitors (anti-cytotoxic T-lymphocyte antigen 4, anti-programmed cell death protein 1 or its ligand, or the combination) for the treatment of advanced melanoma. Main Outcomes and Measures: The association between irAEs and response to therapy, survival, and HLA-DR alleles. Results: Among the cohort of 132 patients with advanced melanoma (mean [SD] age, 63.4 [7.2] years; 85 men [64%] and 47 women [36%]) treated with ICIs, 73 patients had at least 1 irAE and 59 did not have an irAE. Compared with patients without an irAE, patients with an irAE had higher treatment response rates (50 of 72 [69%] vs 28 of 57 [49%]; P = .02) and increased survival (median, 4.8 [IQR, 0.2-9.6] vs 3.2 [IQR, 0.1-9.2] years; P = .02). Specific HLA-DR alleles were associated with the type of irAE that developed: 7 of 10 patients (70%) who developed type 1 diabetes had DR4; 6 of 12 (50%) who developed hypothyroidism had DR8; 5 of 8 (63%) who developed hypophysitis had DR15; 3 of 5 (60%) who developed pneumonitis had DR1; and 8 of 15 (53%) who developed hepatitis had DR4. Conclusions and Relevance: These findings suggest that IrAEs are associated with treatment response rates and increased survival after ICI therapy for advanced melanoma. Because distinct HLA-DR alleles are associated with given adverse events, HLA genotyping before ICI therapy may aid in identifying risk for specific irAEs that could develop with such treatment.

Temporal development of T cell receptor repertoires during childhood in health and disease.

T cell receptor (TCR) sequences are exceptionally diverse and can now be comprehensively measured with next-generation sequencing technologies. However, a thorough investigation of longitudinal TCR repertoires throughout childhood in health and during development of a common childhood disease, type 1 diabetes (T1D), has not been undertaken. Here, we deep sequenced the TCR-ß chain repertoires from longitudinal peripheral blood DNA samples at 4 time points beginning early in life (median age of 1.4 years) from children who progressed to T1D (n = 29) and age/sex-matched islet autoantibody-negative controls (n = 25). From 53 million TCR-ß sequences, we show that the repertoire is extraordinarily diverse early in life and narrows with age independently of disease. We demonstrate the ability to identify specific TCR sequences, including those known to recognize influenza A and, separately, those specific for insulin and its precursor, preproinsulin. Insulin-reactive TCR-ß sequences were more common and frequent in number as the disease progressed in those who developed T1D compared with genetically at risk nondiabetic children, and this was not the case for influenza-reactive sequences. As an independent validation, we sequenced and analyzed TCR-ß repertoires from a cohort of new-onset T1D patients (n = 143), identifying the same preproinsulin-reactive TCRs. These results demonstrate an enrichment of preproinsulin-reactive TCR sequences during the progression to T1D, highlighting the importance of using disease-relevant TCR sequences as powerful biomarkers in autoimmune disorders.