Bridging Mice to Men: Using HLA Transgenic Mice to Enhance the Future Prediction and Prevention of Autoimmune Type 1 Diabetes in Humans.

Similar to the vast majority of cases in humans, the development of type 1 diabetes (T1D) in the NOD mouse model is due to T-cell mediated autoimmune destruction of insulin producing pancreatic β cells. Particular major histocompatibility complex (MHC) haplotypes (designated HLA in humans; and H2 in mice) provide the primary genetic risk factor for T1D development. It has long been appreciated that within the MHC, particular unusual class II genes contribute to the development of T1D in both humans and NOD mice by allowing for the development and functional activation of β cell autoreactive CD4 T cells. However, studies in NOD mice have revealed that through interactions with other background susceptibility genes, the quite common class I variants (K(d), D(b)) characterizing this strain\u27s H2 (g7) MHC haplotype aberrantly acquire an ability to support the development of β cell autoreactive CD8 T cell responses also essential to T1D development. Similarly, recent studies indicate that in the proper genetic context some quite common HLA class I variants also aberrantly contribute to T1D development in humans. This review focuses on how humanized HLA transgenic NOD mice can be created and used to identify class I dependent β cell autoreactive CD8 T cell populations of clinical relevance to T1D development. There is also discussion on how HLA transgenic NOD mice can be used to develop protocols that may ultimately be useful for the prevention of T1D in humans by attenuating autoreactive CD8 T cell responses against pancreatic β cells. Methods Mol Biol 2016; 1438:137-5

HLA-B*39:06 Efficiently Mediates Type 1 Diabetes in a Mouse Model Incorporating Reduced Thymic Insulin Expression.

Type 1 diabetes (T1D) is characterized by T cell-mediated destruction of the insulin-producing β cells of the pancreatic islets. Among the loci associated with T1D risk, those most predisposing are found in the MHC region. HLA-B*39:06 is the most predisposing class I MHC allele and is associated with an early age of onset. To establish an NOD mouse model for the study of HLA-B*39:06, we expressed it in the absence of murine class I MHC. HLA-B*39:06 was able to mediate the development of CD8 T cells, support lymphocytic infiltration of the islets, and confer T1D susceptibility. Because reduced thymic insulin expression is associated with impaired immunological tolerance to insulin and increased T1D risk in patients, we incorporated this in our model as well, finding that HLA-B*39:06-transgenic NOD mice with reduced thymic insulin expression have an earlier age of disease onset and a higher overall prevalence as compared with littermates with typical thymic insulin expression. This was despite virtually indistinguishable blood insulin levels, T cell subset percentages, and TCR Vβ family usage, confirming that reduced thymic insulin expression does not impact T cell development on a global scale. Rather, it will facilitate the thymic escape of insulin-reactive HLA-B*39:06-restricted T cells, which participate in β cell destruction. We also found that in mice expressing either HLA-B*39:06 or HLA-A*02:01 in the absence of murine class I MHC, HLA transgene identity alters TCR Vβ usage by CD8 T cells, demonstrating that some TCR Vβ families have a preference for particular class I MHC alleles. J Immunol 2018 May 15; 200(10):3353-3363

Rapid identification of MHC class I-restricted antigens relevant to autoimmune diabetes using retrogenic T cells.

The method described herein provides a novel strategy for the rapid identification of CD8(+) T cell epitopes relevant to type 1 diabetes in the context of the nonobese diabetic (NOD) mouse model of disease. Obtaining the large number of antigen-sensitive monospecific T cells required for conventional antigen discovery methods has historically been problematic due to (1) difficulties in culturing autoreactive CD8(+) T cells from NOD mice and (2) the large time and resource investments required for the generation of transgenic NOD mice. We circumvented these problems by exploiting the rapid generation time of retrogenic (Rg) mice, relative to transgenic mice, as a novel source of sensitive monospecific CD8(+) T cells, using the diabetogenic AI4 T cell receptor on NOD.SCID and NOD.Rag1(-/-) backgrounds as a model. Rg AI4 T cells are diabetogenic in vivo, demonstrating for the first time that Rg mice are a means for assessing the pathogenic potential of CD8(+) T cell receptor specificities. In order to obtain a sufficient number of Rg CD8(+) T cells for antigen screens, we optimized a method for their in vitro culture that resulted in a approximately 500 fold expansion. We demonstrate the high sensitivity and specificity of expanded Rg AI4 T cells in the contexts of (1) specific peptide challenge, (2) islet cytotoxicity, and (3) their ability to resolve previously defined mimotope candidates from a positional scanning peptide library. Our method is the first to combine the speed of Rg technology with an optimized in vitro Rg T cell expansion protocol to enable the rapid discovery of T cell antigens

On defining the rules for interactions between the T cell receptor and its ligand: A critical role for a specific amino acid residue of the T cell receptor β chain

The specificity of T cell-mediated immune responses is primarily determined by the interaction between the T cell receptor (TCR) and the antigenic peptide presented by the major histocompatibility complex (MHC) molecules. To refine our understanding of interactions between the TCR and the antigenic peptide of vesicular stomatitis virus (VSV) presented by the class I MHC molecule H-2K(b), we constructed a TCR α chain transgenic mouse in a TCR α-deficient background to define specific structural features in the TCR β chain that are important for the recognition of the VSV/H-2K(b) complex. We found that for a given peptide, a peptide-specific, highly conserved amino acid could always be identified at position 98 of the complementarity-determining region 3 (CDR3) loop of TCR β chains. Further, we demonstrated that substitutions at position 6, but not position 1, of the VSV peptide induced compensatory changes in the TCR in both the amino acid residue at position 98 and the length of the CDR3β loop. We conclude that the amino acid residue at position 98 of the CDR3β loop is a key residue that plays a critical role in determining the specificity of TCR–VSV/H-2K(b) interactions and that a specific length of the CDR3β loop is required to facilitate such interactions. Further, these findings suggest that the α and β chains of TCRs interact with amino acid residue(s) toward the N and C termini of the VSV peptide, respectively, providing functional evidence for the orientation of a TCR with its peptide/MHC ligand as observed in the crystal structures of TCR/peptide/MHC complexes