Parenteral insulin suppresses T cell proliferation to islet antigens

Monitoring immunomodulation strategies in type 1 diabetes

Type 1 diabetes (T1D) is a T-cell mediated autoimmune disease. Short-term treatment with agents targeting T cells, B cells and inflammatory cytokines to modify the disease course resulted in a short-term pause in disease activity. Lessons learnt from these trials will be discussed in this review. It is expected that effective disease-modifying agents will become available for use in earlier stages of T1D. Progress has been made to analyze antigen-specific T cells with standardization of T cell assay and discovery of antigen epitopes but there are many challenges. High-dimensional profiling of gene, protein and TCR expression at single cell level with innovative computational tools should lead to novel biomarker discovery. With this, assays to detect, quantify and characterize the phenotype and function of antigen-specific T cells will continuously evolve. An improved understanding of T cell responses will help researchers and clinicians to better predict disease onset, and progression, and the therapeutic efficacy of interventions to prevent or arrest T1D.

B Quiet: Autoantigen-Specific Strategies to Silence Raucous B Lymphocytes and Halt Cross-Talk with T Cells in Type 1 Diabetes

Islet autoantibodies are the primary biomarkers used to predict type 1 diabetes (T1D) disease risk. They signal immune tolerance breach by islet autoantigen-specific B lymphocytes. T-B lymphocyte interactions that lead to expansion of pathogenic T cells underlie T1D development. Promising strategies to broadly prevent this T-B crosstalk include T cell elimination (anti-CD3, teplizumab), B cell elimination (anti-CD20, rituximab), and disruption of T cell costimulation/activation (CTLA-4/Fc fusion, abatacept). However, global disruption or depletion of immune cell subsets is associated with significant risk, particularly in children. Therefore, antigen-specific therapy is an area of active investigation for T1D prevention. We provide an overview of strategies to eliminate antigen-specific B lymphocytes as a means to limit pathogenic T cell expansion to prevent beta cell attack in T1D. Such approaches could be used to prevent T1D in at-risk individuals. Patients with established T1D would also benefit from such targeted therapies if endogenous beta cell function can be recovered or islet transplant becomes clinically feasible for T1D treatment.

Disease modifying therapies in type 1 diabetes: Where have we been, and where are we going?

With more than four decades of clinical research and 25 years of clinical trials, much is known about the natural history of T1D before and after clinical diagnosis. We know that autoimmunity occurs early in life, that islet autoimmunity inevitably leads to clinically overt disease, and that some immune therapies can alter the disease course. In the future, we will likely conduct trials to more deeply explore mechanisms of disease and response to therapy, employ combinations of agents including those aimed at supporting beta cells, consider the use of chronic, intermittent therapy, focus studies on preventing progression from islet autoimmunity, and consider the potential benefits of studying children independently from adults. Much of this work will depend upon clinical trial networks such as Diabetes TrialNet. Such networks not only have the expertise to conduct studies but their sharing of data and samples also allows for discovery work by multiple investigators, laying the groundwork for the future. Working with patients, families, funders and industry, such collaborative networks can accelerate the translation of science to clinical practice to improve the lives of those living with T1D.

Biomarkers for antigen immunotherapy in allergy and type 1 diabetes

Allergy and type 1 diabetes are immune mediated diseases that, despite being etiologically distinct, each have inappropriate activation and effector function of antigen-specific T cells in the pathogenic process. Understanding changes in the frequency and phenotype of these cells is critical to improve assessment of disease diagnosis and prognosis and effectively assess immunological response to therapy. In the setting of antigen-specific therapy in allergy and type 1 diabetes, assays to monitor the immunological mechanisms of disease have been improving in recent years, and we are getting closer to an accurate understanding of how the cellular immune response is modulated during treatment. In this review, we summarize the current state of cell-based immune monitoring of antigen therapy trials. We then discuss emerging advances in antigen-specific biomarkers that are transforming our knowledge about allergy and that have the potential to dramatically impact our understanding of T cell-mediated autoimmune diseases, such as type 1 diabetes.

The Effect of DPT-1 Intravenous Insulin Infusion and Daily Subcutaneous Insulin on Endogenous Insulin Secretion and Postprandial Glucose Tolerance

OBJECTIVE

To investigate the effect of parenteral insulin therapy on endogenous insulin secretion in the Diabetes Prevention Trial-Type 1 (DPT-1).

RESEARCH DESIGN AND METHODS

In the parenteral insulin arm of DPT-1, subjects without diabetes at high risk of future type 1 diabetes randomized to active treatment received a yearly 4-day intravenous insulin infusion (IV-I) and daily subcutaneous insulin (SC-I). To examine the effects of these insulin therapies on endogenous insulin secretion, C-peptide and glucose levels were compared during oral glucose tolerance tests (OGTTs) performed on and off IV-I and SC-I. Forty-six paired OGTTs were performed in 30 subjects from DPT-1 to determine the effect of IV-I. Twenty paired OGTTs were performed in 15 subjects from DPT-1 to determine the effect of SC-I.

RESULTS

IV-I suppressed fasting and OGTT-stimulated C-peptide (62% and 40%, respectively), and it significantly lowered fasting glucose (67.4 ± 4.5 mg/dL during IV-I vs. 90.9 ± 1.8 mg/dL off insulin; P < 0.05). By contrast, post-OGTT glucose levels were significantly higher during IV-I: Glucose during IV-I versus off insulin at 120 min was 203.9 ± 15.1 vs. 151.6 ± 10.2 mg/dL, respectively (P < 0.05); 49% of OGTTs became transiently diabetic (>200 mg/dL at 120 min) when receiving IV-I. Fasting glucose was significantly lower when receiving SC-I versus when off insulin (85 ± 3 vs. 94 ± 2 mg/dL, respectively; P < 0.05), but SC-I did not significantly alter fasting or OGTT-stimulated C-peptide compared with being off insulin.

CONCLUSIONS

These data demonstrate that the IV-I used in the DPT-1 markedly suppressed endogenous insulin secretion, which was frequently associated with postprandial glucose intolerance. SC-I, however, did not.