This abstract was awarded the best paper at the 7th JPEF Annual Global Diabetes Convention 2019.

ABSTRACT TITLE

Novel Molecular Target and Therapeutics for Autoimmune Diabetes

PRESENTING AUTHOR WITH QUALIFICATIONS AND AFFILIATIONS:

Parameswaran Ramakrishnan, M.Sc, Ph.D. Case Western Reserve University and University Hospitals Cleveland Medical Center, Cleveland, OH, USA Cleveland Clinic Foundation, Cleveland, OH, USA Case Comprehensive Cancer Center

LIST OF AUTHORS WITH THEIR WITH QUALIFICATIONS AND AFFILIATIONS:

Jon Pokorski, Ph.D, University of California San Diego, La Jolla, CA, USA Joshua Centore, Case Western Reserve University, Cleveland, OH, USA Derek Church, Ph.D, University of California San Diego, La Jolla, CA, USA Tristan De Jesus, Case Western Reserve University, Cleveland, OH, USA 

ABSTRACT:

Background

Type 1 diabetes is an autoimmune disease associated with hyperglycemia. Adverse pathological effects of hyperglycemia include enhanced hexosamine biosynthetic pathway and intracellular posttranslational modification of proteins by the sugar N-acetyl glucosamine (GlcNAc) in a process called O-GlcNAcylation. We discovered that hyperglycemia increases the O-GlcNAcylation of the transcription factor, nuclear factor kappaB (NF-kB) c-Rel at serine 350. O-GlcNAcylation of c-Rel activates transcription of proautoimmune cytokines, interleukin 2 (IL-2), interferon gamma (IFNG)and granulocyte macrophage-colony stimulating factor (GM-CSF)and inhibits the expression of T-regulatory cell specific transcription factor FOXP3in T cells. These reciprocal effects caused by c-Rel O-GlcNAcylation may act as positive feedback accelerator of autoimmunity under hyperglycemia. Hence, blocking O-GlcNAcylated c-Rel function will have dual benefits in controlling autoimmune diabetes by diminishing the T cell-mediated autoimmunity and enhancing the T-regulatory cell function to suppress autoimmunity.

Aim

To develop agents with therapeutic potential to block the function of O-GlcNAcylated c-Rel to treat autoimmunity in diabetes

Methods

We modeled a modified coarse grained, energy-minimized model of the S350 O-GlcNAcylated c-Rel peptide. We iteratively designed peptoids, a class of peptidomimetics, in silicoand input into molecular docking software and identified peptoid3 with highest affinity for binding to the S350 O-GlcNAcylated c-Rel peptide. We synthesized peptoid3 and scrambled control peptoid using standard sub-monomer synthetic procedures with Rink-Amide resin followed by trifluoroacetic acid cleavage. Peptoids were purified to greater than 90% purity using reverse-phase HPLC and analyzed by mass spectrometry. We examined the effect of peptoid3 treatment on T cell receptor-induced binding of O-GlcNAcylated c-Rel to DNA and autoimmune gene expression in CD4+T cells.

Results and Conclusions

We found that peptoid3 treatment significantly decreased T cell receptor-induced, O-GlcNAcylation-dependent expression of proautoimmune cytokines and enhanced FOXP3 expression in T cells. Peptoid3 treatment selectively affected autoimmunity-associated genes and did not exhibit toxicity on survival or proliferation of T cells. Broad inhibition of hexosamine biosynthetic pathway or NF-kB will cause many side effects due to their ubiquitous importance in multiple biological functions. Therefore, inhibitors of O-GlcNAcylated NF-kB c-Rel function may prove long-sought-after specific molecular therapeutic, with minimal side effects, to diminish autoimmunity in type 1 diabetes.