A Single L/D-Substitution at Q4 of the mInsA2-10 Epitope Prevents Type 1 Diabetes in Humanized NOD Mice.

Mengjun Zhang,Lina Wang,Zhihua Lin,Li Wang,Xiaoling Chen,Gang Meng,Yuanqiang Wang,Xiangqian Li

doi:10.3389/fimmu.2021.713276

Abstract

Autoreactive CD8+ T cells play an indispensable key role in the destruction of pancreatic islet β-cells and the initiation of type 1 diabetes (T1D). Insulin is an essential β-cell autoantigen in T1D. An HLA-A*0201-restricted epitope of insulin A chain (mInsA2-10) is an immunodominant ligand for autoreactive CD8+ T cells in NOD.β2mnull.HHD mice. Altered peptide ligands (APLs) carrying amino acid substitutions at T cell receptor (TCR) contact positions within an epitope are potential to modulate autoimmune responses via triggering altered TCR signaling. Here, we used a molecular simulation strategy to guide the generation of APL candidates by substitution of L-amino acids with D-amino acids at potential TCR contact residues (positions 4 and 6) of mInsA2-10, named mInsA2-10DQ4 and mInsA2-10DC6, respectively. We found that administration of mInsA2-10DQ4, but not DC6, significantly suppressed the development of T1D in NOD.β2mnull.HHD mice. Mechanistically, treatment with mInsA2-10DQ4 not only notably eliminated mInsA2-10 autoreactive CD8+ T cell responses but also prevented the infiltration of CD4+ T and CD8+ T cells, as well as the inflammatory responses in the pancreas of NOD.β2mnull.HHD mice. This study provides a new strategy for the development of APL vaccines for T1D prevention.

Highlights

Type 1 diabetes (T1D) is a spontaneous organ-specific autoimmune disease characterized by T cellmediated elimination of insulin-producing pancreatic islet b-cells
Human leukocyte mInsA2-10 DQ4 Prevents Type 1 Diabetes antigen-A*0201 (HLA-A*0201), one of the most commonly expressed major histocompatibility complex (MHC) class I allele in Caucasians and Asians (50%), has been indicated to contribute to the susceptibility to T1D [8]
We recently found that repeated treatment of Altered peptide ligands (APLs) of mInsB5–14 with histidine to phenylalanine substitution at the potential T cell receptor (TCR) contact site (p6) prevents T1D via selectively expanding a tiny population of CD8+CD25+Foxp3+ regulatory T cells in humanized NOD mice [14]

Summary

Introduction

Type 1 diabetes (T1D) is a spontaneous organ-specific autoimmune disease characterized by T cellmediated elimination of insulin-producing pancreatic islet b-cells. Given the close association between major histocompatibility complex (MHC) class II molecules and type 1 diabetes has been early found [1], b-cell autoreactive CD4+ T cells were the most intensively studied in both humans and NOD mice [2]. The importance of b-cell autoantigen-specific CD8+ T cells in the pathogenesis of type 1 diabetes has been heightened by multiple studies in NOD mice [3,4,5]. Diabetes does not occur in NOD mice depleted of CD8+ T cells by antibody treatment [7]. NOD.b2mnull.HHD mice, carrying human HLA-A*0201 but no murine MHC class I molecules, show significantly accelerated T1D onset [8]. Induction of b-cell autoreactive CD8+ Tcell tolerance has been considered as a promising approach for the prevention of T1D [9]

Methods

Results

Conclusion