Luminex Breakfast Symposium: Pancreas derived peptide presentation by HLA-DQ in Diabetes

Background and purpose of the study

The overall goal of this study is to develop precision-targeted therapies for type 1 diabetes (T1D) by blocking the presentation of pancreatic antigens to T-cells using an innovative translational approach. There is currently no curative therapy for T1D and the only available treatment is insulin replacement, which – although being life-saving – remains problematic and can be associated with often fatal high or low glucose levels. We hypothesize that the presentation of pathogenic pancreatic peptides to T-cells within the HLA-DQ8 pocket is a key trigger in T1D, and that blocking the peptide binding to this pocket can be harnessed to treat/prevent the autoimmune response targeting beta cells in T1D. We propose to block antigen presentation to treat/prevent autoimmunity in T1D using retro-inverso D-amino acid peptides (RIDs). To test our hypothesis, we used the following tools: recombinant human HLA-DQ8, human B cells homozygous for HLA-DQ8, humanized mice expressing human HLA-DQ8, NOD mice, and peripheral blood mononuclear cells (PBMCs) isolated from new onset HLA-DQ8 T1D patients. All of them represent exquisite translational instruments to evaluate in vitro, ex vivo, and in vivo the functional role of our RIDs in preventing beta cell destruction.

Summary of results

We have identified a RID (RI-CT) that inhibits InsB:9-23 binding to recombinant HLA-DQ8 molecule, as well as its binding to HLA-DQ8 expressed on a human B-cell line. Specifically, RI-CT averted T-cell activation in a mixed lymphocyte reaction containing human DQ8 cells loaded with InsB:9-23 peptide and murine T-cells expressing a human TCR specific for the InsB:9-23–DQ8 complex. These results were also confirmed in humanized transgenic B6-DQ8 mice (KO for murine MHC-II) both ex vivo and in vivo, as shown by decreased production of pro-inflammatory cytokines (including IL-2 and IFN-γ) and reduced lymphocyte proliferation. Moreover, RI-CT prevents autoimmune diabetes in NOD mice as demonstrated by a significant decrease in pancreatic immune cell infiltration in treated mice versus controls. Importantly, at 25 weeks of age 70% of RI-CT treated mice were protected from the development of diabetes, while as expected 80% of control NOD mice had developed the disease. Interestingly, RI-CT injection also altered T-cell subpopulations in NOD mice significantly decreasing CD8 expression and significantly increasing Foxp3 levels in treated mice. Of note, RI-CT significantly inhibits InsB:9-23-mediated lymphocyte activation in peripheral blood mononuclear cells isolated from new onset DQ8-T1D patients.

Conclusions

In summary, we discovered a RID that blocks InsB:9-23 binding to HLA-DQ8 and its presentation to T-cells averting beta cells destruction, and that delays T1D in NOD mice. These data set the stage for using our approach of blocking antigen presentation by RID as a novel therapeutic approach for autoimmune diseases in general.

Speaker BIO:

Dr. Angela Lombardi, PhD, MSc

Dr. Lombardi is an Assistant Professor in the Division of Endocrinology, Department of Medicine, and in the Department of Immunology and Microbiology, at the Albert Einstein College of Medicine in New York. She has been studying the pathophysiology of endocrine disorders for almost 20 years. Her studies led to the identification of novel mechanisms underlying both type 2 (T2D) and type 1 diabetes (T1D). During her PhD at the University of Naples “Federico II” (Italy) she demonstrated the mechanistic role of beta 2 adrenergic receptor in aging-related impaired insulin secretion and glucose homeostasis. Later, during her postdoc at the Icahn School of Medicine at Mount Sinai (New York), she studied novel environmental triggers in T1D, and as a faculty member at the Albert Einstein College of Medicine she investigated new mechanisms underlying beta cell death in patients undergoing immunosuppression. More recently Dr. Lombardi has been translating her mechanistic findings into novel therapeutic approaches for T1D based on blocking antigen presentation. Her ongoing research projects aim at preventing and treating autoimmune destruction of beta cells and beta cell dysfunction.