Monoclonal antibody blocking the recognition of an insulin peptide–MHC complex modulates type 1 diabetes

Abstract

The primary autoantigen triggering spontaneous type 1 diabetes mellitus in nonobese diabetic (NOD) mice is insulin. The major T-cell insulin epitope lies within the amino acid 9-23 peptide of the β-chain (B:9-23). This peptide can bind within the peptide binding groove of the NOD MHC class II molecule (MHCII), IA g7 , in multiple positions or "registers." However, the majority of pathogenic CD4 T cells recognize this complex only when the insulin peptide is bound in register 3 (R3). We hypothesized that antibodies reacting specifically with R3 insulin-IA g7 complexes would inhibit autoimmune diabetes specifically without interfering with recognition of other IA g7 -presented antigens. To test this hypothesis, we generated a monoclonal antibody (mAb287), which selectively binds to B:9-23 and related variants when presented by IA g7 in R3, but not other registers. The monoclonal antibody blocks binding of IA g7 -B:10-23 R3 tetramers to cognate T cells and inhibits T-cell responses to soluble B:9-23 peptides and NOD islets. However, mAb287 has no effect on recognition of other peptides bound to IA g7 or other MHCII molecules. Intervention with mAb287, but not irrelevant isotype matched antibody, at either early or late stages of disease development, significantly delayed diabetes onset by inhibiting infiltration by not only insulin-specific CD4 T cells, but also by CD4 and CD8 T cells of other specificities. We propose that peptide-MHC-specific monoclonal antibodies can modulate autoimmune disease without the pleiotropic effects of nonselective reagents and, thus, could be applicable to the treatment of multiple T-cell mediated autoimmune disorders.immunotherapy | antigen processing I n the nonobese diabetic (NOD) mouse, a spontaneous mouse model of type 1 diabetes mellitus (T1DM), autoimmune targeting of (pro)insulin appears essential for development of disease (1-7). For example, 90 percent of CD4 + insulin-reactive T-cell clones isolated from the islets of prediabetic NOD mice target the insulin β-chain 9-23 peptide (B:9-23) (8, 9), and this peptide is likely the primary epitope recognized by T cells that either induce (6, 7, 9) or prevent T1DM (8)(9)(10)(11)(12)(13)(14). Similarly, autoimmunity to insulin is essential for the loss of tolerance to the β-cell antigen islet-specific glucose 6 phosphatase catalytic subunit-related protein (IGRP) (11,15), but the converse is not true. The NOD mouse expresses a single MHC class II (MHCII) molecule, IA g7 , whose presence is essential for the development of T1DM (16-18). We previously suggested that a particular version of IA g7 -insulin B:9-23 complex is crucial for the initiation of islet autoimmunity in the NOD mouse (19)(20)(21)(22) and that a homologous complex involving the structurally related MHCII molecules human leukocyte antigen DQ8 (HLA-DQ8) and HLA-DQ2 may play a similar role in humans (23-25).As with other MHCII molecules, the selective binding of peptides to the IA g7 peptide binding groove is governed by interactions between the side chains at particul...

Regulatory vs. inflammatory cytokine T-cell responses to mutated insulin peptides in healthy and type 1 diabetic subjects

“…Therefore, because of its superagonist properties, the potential exists to use the insulin B22E mimotope as a tolerogenic vaccine in those at risk for T1D. In other studies, antibodies specific for the register 3 B:9-23/IA g7 complex inhibit T-cell responses in vitro and delay T1D onset in vivo in NOD mice (31,32), opening another potential avenue for antigen-specific therapy. Our results also raise the possibility that individuals with a β57D + -containing DQ allele may have the ability to produce a regulatory response to the insulin epitope.…”

ω-3 polyunsaturated fatty acids ameliorate type 1 diabetes and autoimmunity

“…The NOD (J001976) mouse colony, which was the same colony used in most of the other published studies (71)(72)(73), was purchased from The Jackson Laboratory and maintained in a strict specific pathogen-free (SPF) barrier facility at the Model Animal Research Center of Nanjing University. Both male and female NOD mice were tested regularly (at least every 3 months) for microbiological screening when housed at the barrier facility.…”

Immunogenetics of type 1 diabetes mellitus

“…The interaction between the components of the trimolecular complex (CD4 + T cell receptors, self-peptide, and MHC class II molecules) plays a pivotal role in autoimmune disease pathogenesis. The development of therapies targeting various components of the trimolecular complex for the prevention of type 1 diabetes is actively being pursued (Michels, 2013; Zhang et al, 2014). …”