Defective Proinsulin Handling Modulates the MHC I Bound Peptidome and Activates the Inflammasome in β-Cells

T cell receptor-engineered T cells derived from target human leukocyte antigen-DPB1-specific T cell can be a potential tool for therapy against leukemia relapse following allogeneic hematopoietic cell transplantation

Human leukocyte antigen (HLA)-DPB1 antigens are mismatched in approximately 70% of allogeneic hematopoietic stem cell transplantations (allo-HSCT) from HLA 10/10 matched unrelated donors. HLA-DP-mismatched transplantation was shown to be associated with an increase in acute graft-versus-host disease (GVHD) and a decreased risk of leukemia relapse due to the graft-versus-leukemia (GVL) effect. Immunotherapy targeting mismatched HLA-DP is considered reasonable to treat leukemia following allo-HCT if performed under non-inflammatory conditions. Therefore, we isolated CD4+ T cell clones that recognize mismatched HLA-DPB1 from healthy volunteer donors and generated T cell receptor (TCR)-gene-modified T cells for future clinical applications. Detailed analysis of TCR-T cells expressing TCR from candidate clone #17 demonstrated specificity to myeloid and monocytic leukemia cell lines that even expressed low levels of targeted HLA-DP. However, they did not react to non-hematopoietic cell lines with a substantial level of targeted HLA-DP expression, suggesting that the TCR recognized antigenic peptide is only present in some hematopoietic cells. This study demonstrated that induction of T cells specific for HLA-DP, consisting of hematopoietic cell lineage-derived peptide and redirection of T cells with cloned TCR cDNA by gene transfer, is feasible when using careful specificity analysis.

Using mass spectrometry to identify neoantigens in autoimmune diseases: The type 1 diabetes example

In autoimmune diseases, recognition of self-antigens presented by major histocompatibility complex (MHC) molecules elicits unexpected attack of tissue by autoantibodies and/or autoreactive T cells. Post-translational modification (PTM) may alter the MHC-binding motif or TCR contact residues in a peptide antigen, transforming the tolerance to self to autoreactivity. Mass spectrometry-based immunopeptidomics provides a valuable mechanism for identifying MHC ligands that contain PTMs and can thus provide valuable insights into pathogenesis and therapeutics of autoimmune diseases. A plethora of PTMs have been implicated in this process, and this review highlights their formation and identification.

Proteomic identification of MHC class I-associated peptidome derived from non-obese diabetic mouse thymus and pancreas

The peptides repertoire presented to CD8⁺ T cells by major histocompatibility complex (MHC) class I molecules is referred to as the MHC I-associated peptidome (MIP), which regulates thymus development, peripheral survival and function during lifetime of CD8⁺ T cells. Type 1 diabetes (T1D) is an organ-specific autoimmune disease caused by pancreatic β cells destruction mediated primarily by autoreactive CD8⁺ T cells. Non-obese diabetic (NOD) mouse is an important animal model of T1D. Here, we deeply analyzed the MIP derived from NOD mice thymus and pancreas, and demonstrated that the thymus MIP source proteins partially shared with the MIP source proteins derived from NOD mice pancreas and β cell line. One H-2Kd restricted peptide SLC35B1_26-34 which was shared by MIP derived from both NOD mice pancreatic tissues and islet β-cell line, but absent in MIP from NOD thymus tissues, showed ability to stimulate IFN-γ secretion and proliferation of NOD mice splenic CD8⁺ T cells. The global view of the MHC I-associated self-peptides repertoire in the thymus and pancreas of NOD mice may serve as a biological reference to identify potential autoantigens targeted by autoreactive CD8⁺ T cells in T1D. Data are available via ProteomeXchange with identifier PXD031966. SIGNIFICANCE: The peptides repertoire presented to CD8⁺ T cells by major histocompatibility complex (MHC) class I molecules is referred to as the MHC I-associated peptidome (MIP). The MIP presented by thymic antigen presenting cells (APCs) is crucial for shaping CD8⁺ T cell repertoire and self-tolerance, while the MIP presented by peripheral tissues and organs is not only involved in maintaining periphery CD8⁺ T cell survival and homeostasis, but also mediates immune surveillance and autoimmune responses of CD8⁺ T cells under pathological conditions. Type 1 diabetes (T1D) is an organ-specific autoimmune disease caused by the destruction of pancreatic β cells, mediated primarily by autoreactive CD8⁺ T cells. Non-obese diabetic (NOD) mouse is one of important animal models of spontaneous autoimmune diabetes that shares several key features with human T1D. The global view of the MHC I-associated self-peptides repertoire in the thymus and pancreas of NOD mice may serve as a good biological reference to identify potential autoantigens targeted by autoreactive CD8⁺ T cells in T1D. It has great significance for further clarifying the immune recognition and effect mechanism of autoreactive CD8⁺ T cells in the pathogenesis of T1D, and then developing antigen-specific immune intervention strategies.