109-OR: T-Cell Responses to Hybrid Insulin Peptides Precede Type 1 Diabetes Development
Authors: MITCHELL ANGELA M. , ALKANANI AIMON , MCDANIEL KRISTEN , PYLE LAURA , WAUGH KATHLEEN , STECK ANDREA , NAKAYAMA MAKI , YU LIPING , GOTTLIEB PETER , REWERS MARIAN , MICHELS AARON W. 
Published: June 2021

Type 1 diabetes (T1D) results from the T cell-mediated destruction of insulin-producing beta-cells within pancreatic islets. T cell responses to post-translationally modified hybrid insulin peptides (HIPs) have been implicated in T1D pathogenesis, and we hypothesized that CD4 T cell responses to HIPs precede clinical diabetes onset. Therefore, we measured longitudinal T cell responses to native and hybrid insulin peptides in a cohort of genetically at-risk individuals from the Diabetes AutoImmunity Study in the Young (DAISY). Using cytokine ELISPOT assays, both pro-inflammatory (IFN-γ) and anti-inflammatory (IL-10) cytokine responses to HIPs were more robust than to native peptides. Three of the 38 autoantibody negative individuals (med. age 18.7 yrs) developed islet autoimmunity during 2 years of follow-up, and the C-peptide-islet amyloid polypeptide-2 (C:IAPP-2), C-peptide-neuropeptide Y (C:NPY), and C-peptide-insulin A chain (C:A chain) HIPs induced more frequent pro-inflammatory T cell responses compared to those that did not develop autoantibodies. Five of the 25 autoantibody positive individuals (med. age 18.7 yrs) progressed to clinical T1D during the study, and the C:IAPP-2 HIP more frequently induced a pro-inflammatory response compared to those that did not progress (p=0.037). Additionally, length of time from autoantibody seroconversion correlated with proinflammatory T cell responses to the insulin B:9-23 (B22E) HIP (p=0.007) and the native B:9-23 peptide (p=0.022). T cell responses to the B22E HIP also strongly correlated with insulin autoantibody levels (p=0.0001). Furthermore, responses to the C:IAPP-2 HIP correlated with worsening measurements of blood glucose (A1c %, p=0.046; glucose area under the curve, p=0.054). Monitoring T cell responses to post-translationally modified antigens prior to T1D onset holds promise for determining which individuals are likely to progress to clinical disease and may benefit from immune intervention to prevent T1D onset.

Disclosure
A. M. Mitchell: None. M. Rewers: Advisory Panel; Self; Provention Bio, Inc., Consultant; Self; RTI, Research Support; Self; Janssen Research & Development, LLC, JDRF. A. W. Michels: Stock/Shareholder; Self; IM Therapeutics. A. Alkanani: None. K. Mcdaniel: None. L. Pyle: None. K. Waugh: None. A. Steck: None. M. Nakayama: None. L. Yu: None. P. Gottlieb: Advisory Panel; Self; Janssen Research & Development, LLC, Tolerion, Inc., Viacyte, Inc., Other Relationship; Self; ImmunoMolecular Therapeutics, Inc., Research Support; Self; Caladrius Biosciences, Inc., Immune Tolerance Network, Mercia Pharma Inc., National Institute of Diabetes and Digestive and Kidney Diseases, Precigen, Inc., Tolerion, Inc.

Funding
National Institutes of Health (DK108868, DK110845, DK032083, DK032493, DK116073); JDRF (3-PDF-2020-943-A-N); Children’s Diabetes Foundation; Colorado Clinical and Translational Science Institute (TR002535)