1
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Mishto M, Takala I, Bonfanti P, Liepe J. Proteasome isoforms in human thymi and mouse models. Immunol Lett 2024; 269:106899. [PMID: 39019403 DOI: 10.1016/j.imlet.2024.106899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 07/02/2024] [Accepted: 07/13/2024] [Indexed: 07/19/2024]
Abstract
The thymus is the organ where functional and self-tolerant T cells are selected through processes of positive and negative selection before migrating to the periphery. The antigenic peptides presented on MHC class I molecules of thymic epithelial cells (TECs) in the cortex and medulla of the thymus are key players in these processes. It has been theorized that these cells express different proteasome isoforms, which generate MHC class I immunopeptidomes with features that differentiate cortex and medulla, and hence positive and negative CD8+ T cell selection. This theory is largely based on mouse models and does not consider the large variety of noncanonical antigenic peptides that could be produced by proteasomes and presented on MHC class I molecules. Here, we review the multi-omics, biochemical and cellular studies carried out on mouse models and human thymi to investigate their content of proteasome isoforms, briefly summarize the implication that noncanonical antigenic peptide presentation in the thymus could have on CD8+ T cell repertoire and put these aspects in the larger framework of anatomical and immunological differences between these two species.
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Affiliation(s)
- Michele Mishto
- Molecular Immunology laboratory, the Francis Crick Institute, NW1 1AT London, United Kingdom; Centre for Inflammation Biology and Cancer Immunology & Peter Gorer Department of Immunobiology, King's College London, SE1 1UL London, United Kingdom.
| | - Iina Takala
- Research group of Quantitative System Biology, Max-Planck-Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Paola Bonfanti
- Epithelial Stem Cell Biology & Regenerative Medicine laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom; Institute of Immunity & Transplantation, Division of Infection & Immunity, UCL, Pears Building, London NW3 2PP, United Kingdom
| | - Juliane Liepe
- Research group of Quantitative System Biology, Max-Planck-Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
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2
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Soh WT, Roetschke HP, Cormican JA, Teo BF, Chiam NC, Raabe M, Pflanz R, Henneberg F, Becker S, Chari A, Liu H, Urlaub H, Liepe J, Mishto M. Protein degradation by human 20S proteasomes elucidates the interplay between peptide hydrolysis and splicing. Nat Commun 2024; 15:1147. [PMID: 38326304 PMCID: PMC10850103 DOI: 10.1038/s41467-024-45339-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 01/17/2024] [Indexed: 02/09/2024] Open
Abstract
If and how proteasomes catalyze not only peptide hydrolysis but also peptide splicing is an open question that has divided the scientific community. The debate has so far been based on immunopeptidomics, in vitro digestions of synthetic polypeptides as well as ex vivo and in vivo experiments, which could only indirectly describe proteasome-catalyzed peptide splicing of full-length proteins. Here we develop a workflow-and cognate software - to analyze proteasome-generated non-spliced and spliced peptides produced from entire proteins and apply it to in vitro digestions of 15 proteins, including well-known intrinsically disordered proteins such as human tau and α-Synuclein. The results confirm that 20S proteasomes produce a sizeable variety of cis-spliced peptides, whereas trans-spliced peptides are a minority. Both peptide hydrolysis and splicing produce peptides with well-defined characteristics, which hint toward an intricate regulation of both catalytic activities. At protein level, both non-spliced and spliced peptides are not randomly localized within protein sequences, but rather concentrated in hotspots of peptide products, in part driven by protein sequence motifs and proteasomal preferences. At sequence level, the different peptide sequence preference of peptide hydrolysis and peptide splicing suggests a competition between the two catalytic activities of 20S proteasomes during protein degradation.
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Affiliation(s)
- Wai Tuck Soh
- Research Group of Quantitative and Systems Biology, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Hanna P Roetschke
- Research Group of Quantitative and Systems Biology, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
- Centre for Inflammation Biology and Cancer Immunology & Peter Gorer Department of Immunobiology, King's College London, SE1 1UL, London, UK
- Research Group of Molecular Immunology, Francis Crick Institute, NW1 1AT, London, UK
| | - John A Cormican
- Research Group of Quantitative and Systems Biology, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Bei Fang Teo
- Centre for Inflammation Biology and Cancer Immunology & Peter Gorer Department of Immunobiology, King's College London, SE1 1UL, London, UK
- Research Group of Molecular Immunology, Francis Crick Institute, NW1 1AT, London, UK
- Immunology Programme, Life Sciences Institute; Immunology Translational Research Program and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117456, Singapore
| | - Nyet Cheng Chiam
- Research Group of Quantitative and Systems Biology, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Monika Raabe
- Research Group of Bioanalytical Mass Spectrometry, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Ralf Pflanz
- Research Group of Bioanalytical Mass Spectrometry, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Fabian Henneberg
- Department of Structural Dynamics, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Stefan Becker
- Department of NMR-based Structural Biology, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Ashwin Chari
- Research Group of Structural Biochemistry and Mechanisms, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Haiyan Liu
- Immunology Programme, Life Sciences Institute; Immunology Translational Research Program and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117456, Singapore
| | - Henning Urlaub
- Research Group of Bioanalytical Mass Spectrometry, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
- Institute of Clinical Chemistry, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Juliane Liepe
- Research Group of Quantitative and Systems Biology, Max-Planck-Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany.
| | - Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology & Peter Gorer Department of Immunobiology, King's College London, SE1 1UL, London, UK.
- Research Group of Molecular Immunology, Francis Crick Institute, NW1 1AT, London, UK.
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3
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Lichti CF, Wan X. Using mass spectrometry to identify neoantigens in autoimmune diseases: The type 1 diabetes example. Semin Immunol 2023; 66:101730. [PMID: 36827760 PMCID: PMC10324092 DOI: 10.1016/j.smim.2023.101730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 02/06/2023] [Accepted: 02/09/2023] [Indexed: 02/24/2023]
Abstract
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.
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Affiliation(s)
- Cheryl F Lichti
- Department of Pathology and Immunology, Division of Immunobiology, The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8118, St. Louis, MO 63110, USA.
| | - Xiaoxiao Wan
- Department of Pathology and Immunology, Division of Immunobiology, The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8118, St. Louis, MO 63110, USA.
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4
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Roetschke HP, Rodriguez-Hernandez G, Cormican JA, Yang X, Lynham S, Mishto M, Liepe J. InvitroSPI and a large database of proteasome-generated spliced and non-spliced peptides. Sci Data 2023; 10:18. [PMID: 36627305 PMCID: PMC9832164 DOI: 10.1038/s41597-022-01890-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 12/01/2022] [Indexed: 01/12/2023] Open
Abstract
Noncanonical epitopes presented by Human Leucocyte Antigen class I (HLA-I) complexes to CD8+ T cells attracted the spotlight in the research of novel immunotherapies against cancer, infection and autoimmunity. Proteasomes, which are the main producers of HLA-I-bound antigenic peptides, can catalyze both peptide hydrolysis and peptide splicing. The prediction of proteasome-generated spliced peptides is an objective that still requires a reliable (and large) database of non-spliced and spliced peptides produced by these proteases. Here, we present an extended database of proteasome-generated spliced and non-spliced peptides, which was obtained by analyzing in vitro digestions of 80 unique synthetic polypeptide substrates, measured by different mass spectrometers. Peptides were identified through invitroSPI method, which was validated through in silico and in vitro strategies. The peptide product database contains 16,631 unique peptide products (5,493 non-spliced, 6,453 cis-spliced and 4,685 trans-spliced peptide products), and a substrate sequence variety that is a valuable source for predictors of proteasome-catalyzed peptide hydrolysis and splicing. Potential artefacts and skewed results due to different identification and analysis strategies are discussed.
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Affiliation(s)
- Hanna P Roetschke
- Max-Planck-Institute for Multidisciplinary Sciences (MPI-NAT), 37077, Göttingen, Germany
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London (KCL), SE1 1UL, London, UK
| | - Guillermo Rodriguez-Hernandez
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London (KCL), SE1 1UL, London, UK
- Francis Crick Institute, NW1 1AT, London, UK
| | - John A Cormican
- Max-Planck-Institute for Multidisciplinary Sciences (MPI-NAT), 37077, Göttingen, Germany
| | - Xiaoping Yang
- Proteomics Core Facility, James Black Centre, King's College London (KCL), SE5 9NU, London, UK
| | - Steven Lynham
- Proteomics Core Facility, James Black Centre, King's College London (KCL), SE5 9NU, London, UK
| | - Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London (KCL), SE1 1UL, London, UK.
- Francis Crick Institute, NW1 1AT, London, UK.
| | - Juliane Liepe
- Max-Planck-Institute for Multidisciplinary Sciences (MPI-NAT), 37077, Göttingen, Germany.
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5
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Targeting immunoproteasome in neurodegeneration: A glance to the future. Pharmacol Ther 2023; 241:108329. [PMID: 36526014 DOI: 10.1016/j.pharmthera.2022.108329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/15/2022]
Abstract
The immunoproteasome is a specialized form of proteasome equipped with modified catalytic subunits that was initially discovered to play a pivotal role in MHC class I antigen processing and immune system modulation. However, over the last years, this proteolytic complex has been uncovered to serve additional functions unrelated to antigen presentation. Accordingly, it has been proposed that immunoproteasome synergizes with canonical proteasome in different cell types of the nervous system, regulating neurotransmission, metabolic pathways and adaptation of the cells to redox or inflammatory insults. Hence, studying the alterations of immunoproteasome expression and activity is gaining research interest to define the dynamics of neuroinflammation as well as the early and late molecular events that are likely involved in the pathogenesis of a variety of neurological disorders. Furthermore, these novel functions foster the perspective of immunoproteasome as a potential therapeutic target for neurodegeneration. In this review, we provide a brain and retina-wide overview, trying to correlate present knowledge on structure-function relationships of immunoproteasome with the variety of observed neuro-modulatory functions.
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An unexplored angle: T cell antigen discoveries reveal a marginal contribution of proteasome splicing to the immunogenic MHC class I antigen pool. Proc Natl Acad Sci U S A 2022; 119:e2119736119. [PMID: 35858315 PMCID: PMC9303865 DOI: 10.1073/pnas.2119736119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the current era of T cell–based immunotherapies, it is crucial to understand which types of MHC-presented T cell antigens are produced by tumor cells. In addition to linear peptide antigens, chimeric peptides are generated through proteasome-catalyzed peptide splicing (PCPS). Whether such spliced peptides are abundantly presented by MHC is highly disputed because of disagreement in computational analyses of mass spectrometry data of MHC-eluted peptides. Moreover, such mass spectrometric analyses cannot elucidate how much spliced peptides contribute to the pool of immunogenic antigens. In this Perspective, we explain the significance of knowing the contribution of spliced peptides for accurate analyses of peptidomes on one hand, and to serve as a potential source of targetable tumor antigens on the other hand. Toward a strategy for mass spectrometry independent estimation of the contribution of PCPS to the immunopeptidome, we first reviewed methodologies to identify MHC-presented spliced peptide antigens expressed by tumors. Data from these identifications allowed us to compile three independent datasets containing 103, 74, and 83 confirmed T cell antigens from cancer patients. Only 3.9%, 1.4%, and between 0% and 7.2% of these truly immunogenic antigens are produced by PCPS, therefore providing a marginal contribution to the pool of immunogenic tumor antigens. We conclude that spliced peptides will not serve as a comprehensive source to expand the number of targetable antigens for immunotherapies.
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7
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Ferrari V, Stroobant V, Abi Habib J, Naulaerts S, Van den Eynde BJ, Vigneron N. New Insights into the Mechanisms of Proteasome-Mediated Peptide Splicing Learned from Comparing Splicing Efficiency by Different Proteasome Subtypes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:2817-2828. [PMID: 35688464 DOI: 10.4049/jimmunol.2101198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 04/03/2022] [Indexed: 06/15/2023]
Abstract
By tying peptide fragments originally distant in parental proteins, the proteasome can generate spliced peptides that are recognized by CTL. This occurs by transpeptidation involving a peptide-acyl-enzyme intermediate and another peptide fragment present in the catalytic chamber. Four main subtypes of proteasomes exist: the standard proteasome (SP), the immunoproteasome, and intermediate proteasomes β1-β2-β5i (single intermediate proteasome) and β1i-β2-β5i (double intermediate proteasome). In this study, we use a tandem mass tag-quantification approach to study the production of six spliced human antigenic peptides by the four proteasome subtypes. Peptides fibroblast growth factor-5172-176/217-220, tyrosinase368-373/336-340, and gp10040-42/47-52 are better produced by the SP than the other proteasome subtypes. The peptides SP110296-301/286-289, gp100195-202/191or192, and gp10047-52/40-42 are better produced by the immunoproteasome and double intermediate proteasome. The current model of proteasome-catalyzed peptide splicing suggests that the production of a spliced peptide depends on the abundance of the peptide splicing partners. Surprisingly, we found that despite the fact that reciprocal peptides RTK_QLYPEW (gp10040-42/47-52) and QLYPEW_RTK (gp10047-52/40-42) are composed of identical splicing partners, their production varies differently according to the proteasome subtype. These differences were maintained after in vitro digestions involving identical amounts of the splicing fragments. Our results indicate that the amount of splicing partner is not the only factor driving peptide splicing and suggest that peptide splicing efficiency also relies on other factors, such as the affinity of the C-terminal splice reactant for the primed binding site of the catalytic subunit.
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Affiliation(s)
- Violette Ferrari
- Ludwig Institute for Cancer Research, Brussels, Belgium
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Walloon Excellence in Lifesciences and Biotechnology, Brussels, Belgium; and
| | - Vincent Stroobant
- Ludwig Institute for Cancer Research, Brussels, Belgium
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Walloon Excellence in Lifesciences and Biotechnology, Brussels, Belgium; and
| | - Joanna Abi Habib
- Ludwig Institute for Cancer Research, Brussels, Belgium
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Walloon Excellence in Lifesciences and Biotechnology, Brussels, Belgium; and
| | - Stefan Naulaerts
- Ludwig Institute for Cancer Research, Brussels, Belgium
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Walloon Excellence in Lifesciences and Biotechnology, Brussels, Belgium; and
| | - Benoit J Van den Eynde
- Ludwig Institute for Cancer Research, Brussels, Belgium;
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Walloon Excellence in Lifesciences and Biotechnology, Brussels, Belgium; and
- Nuffield Department of Medicine, Ludwig Institute for Cancer Research, University of Oxford, Oxford, United Kingdom
| | - Nathalie Vigneron
- Ludwig Institute for Cancer Research, Brussels, Belgium;
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Walloon Excellence in Lifesciences and Biotechnology, Brussels, Belgium; and
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8
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Kloetzel PM. Neo-Splicetopes in Tumor Therapy: A Lost Case? Front Immunol 2022; 13:849863. [PMID: 35265089 PMCID: PMC8898901 DOI: 10.3389/fimmu.2022.849863] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 02/03/2022] [Indexed: 11/13/2022] Open
Abstract
Proteasome generates spliced peptides by ligating two distant cleavage products in a reverse proteolysis reaction. The observation that CD8+ T cells recognizing a spliced peptide induced T cell rejection in a melanoma patient following adoptive T cell transfer (ATT), raised some hopes with regard to the general therapeutic and immune relevance of spliced peptides. Concomitantly, the identification of spliced peptides was also the start of a controversy with respect to their frequency, abundancy and their therapeutic applicability. Here I review some of the recent evidence favoring or disfavoring an immune relevance of splicetopes and discuss from a theoretical point of view the potential usefulness of tumor specific splicetopes and why against all odds it still may seem worth trying to identify such tumor and patient-specific neosplicetopes for application in ATT.
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Affiliation(s)
- Peter M Kloetzel
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Biochemistry, Berlin, Germany
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9
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Functional Differences between Proteasome Subtypes. Cells 2022; 11:cells11030421. [PMID: 35159231 PMCID: PMC8834425 DOI: 10.3390/cells11030421] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/11/2022] [Accepted: 01/14/2022] [Indexed: 12/30/2022] Open
Abstract
Four proteasome subtypes are commonly present in mammalian tissues: standard proteasomes, which contain the standard catalytic subunits β1, β2 and β5; immunoproteasomes containing the immuno-subunits β1i, β2i and β5i; and two intermediate proteasomes, containing a mix of standard and immuno-subunits. Recent studies revealed the expression of two tissue-specific proteasome subtypes in cortical thymic epithelial cells and in testes: thymoproteasomes and spermatoproteasomes. In this review, we describe the mechanisms that enable the ATP- and ubiquitin-dependent as well as the ATP- and ubiquitin-independent degradation of proteins by the proteasome. We focus on understanding the role of the different proteasome subtypes in maintaining protein homeostasis in normal physiological conditions through the ATP- and ubiquitin-dependent degradation of proteins. Additionally, we discuss the role of each proteasome subtype in the ATP- and ubiquitin-independent degradation of disordered proteins. We also discuss the role of the proteasome in the generation of peptides presented by MHC class I molecules and the implication of having different proteasome subtypes for the peptide repertoire presented at the cell surface. Finally, we discuss the role of the immunoproteasome in immune cells and its modulation as a potential therapy for autoimmune diseases.
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10
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Barbosa CRR, Barton J, Shepherd AJ, Mishto M. Mechanistic diversity in MHC class I antigen recognition. Biochem J 2021; 478:4187-4202. [PMID: 34940832 PMCID: PMC8786304 DOI: 10.1042/bcj20200910] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/16/2021] [Accepted: 11/18/2021] [Indexed: 12/20/2022]
Abstract
Throughout its evolution, the human immune system has developed a plethora of strategies to diversify the antigenic peptide sequences that can be targeted by the CD8+ T cell response against pathogens and aberrations of self. Here we provide a general overview of the mechanisms that lead to the diversity of antigens presented by MHC class I complexes and their recognition by CD8+ T cells, together with a more detailed analysis of recent progress in two important areas that are highly controversial: the prevalence and immunological relevance of unconventional antigen peptides; and cross-recognition of antigenic peptides by the T cell receptors of CD8+ T cells.
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Affiliation(s)
- Camila R. R. Barbosa
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, SE1 1UL London, U.K
- Francis Crick Institute, NW1 1AT London, U.K
| | - Justin Barton
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London, WC1E 7HX London, U.K
| | - Adrian J. Shepherd
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London, WC1E 7HX London, U.K
| | - Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, SE1 1UL London, U.K
- Francis Crick Institute, NW1 1AT London, U.K
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11
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Mishto M. Commentary: Are There Indeed Spliced Peptides in the Immunopeptidome? Mol Cell Proteomics 2021; 20:100158. [PMID: 34607014 PMCID: PMC8724881 DOI: 10.1016/j.mcpro.2021.100158] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/22/2021] [Accepted: 09/27/2021] [Indexed: 11/27/2022] Open
Abstract
Proteasome-generated spliced epitopes presented by HLA class I complexes are emerging targets for T cell targeted immunotherapies. Their identification by mass spectrometry triggered heated debates, which find a representative opinion in one of the two fronts in the recent perspective article by Arie Admon. Briefly, he suggests that proteasomes cannot efficiently catalyze such a reaction, and, thus, that all spliced peptides identified in HLA class I immunopeptidomes and other specimens are artifacts. This hypothesis is in contrast with in vitro, in cellula, and in vivo results published since the discovery of proteasome-catalyzed peptide splicing in 2004.
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Affiliation(s)
- Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, London, United Kingdom; Francis Crick Institute, London, United Kingdom.
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12
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Mishto M, Rodriguez-Hernandez G, Neefjes J, Urlaub H, Liepe J. Response: Commentary: An In Silico-In Vitro Pipeline Identifying an HLA-A*02:01+ KRAS G12V+ Spliced Epitope Candidate for a Broad Tumor-Immune Response in Cancer Patients. Front Immunol 2021; 12:679836. [PMID: 34326838 PMCID: PMC8315000 DOI: 10.3389/fimmu.2021.679836] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/17/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
- Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, London, United Kingdom
- Francis Crick Institute, London, United Kingdom
| | - Guillermo Rodriguez-Hernandez
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, London, United Kingdom
- Francis Crick Institute, London, United Kingdom
| | - Jacques Neefjes
- Department of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center (LUMC), Leiden, Netherlands
| | - Henning Urlaub
- Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
- Bioanalytics, Institute of Clinical Chemistry, University Medical Center, Göttingen, Germany
| | - Juliane Liepe
- Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
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13
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Admon A. Are There Indeed Spliced Peptides in the Immunopeptidome? Mol Cell Proteomics 2021; 20:100099. [PMID: 34022431 PMCID: PMC8724635 DOI: 10.1016/j.mcpro.2021.100099] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/13/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022] Open
Abstract
The claims that a large fraction of the immunopeptidome is composed of spliced major histocompatibility complex (MHC) peptides have stirred significant excitement and raised controversy. Here, I suggest that there are likely no spliced peptides in the immunopeptidome, and if they exist at all, they are extremely rare. I base this claim on both biochemical and bioinformatics considerations. First, as a reactant in normal proteolytic reactions, water will compete with transpeptidation, which has been suggested as the mechanism of peptide splicing. The high mobility and abundance of water in aqueous solutions renders transpeptidation very inefficient and therefore unlikely to occur. Second, new studies have refuted the bioinformatics assignments to spliced peptides of most of the immunopeptidome MS data, suggesting that the correct assignments are likely other canonical, noncanonical, and post-translationally modified peptides. Therefore, I call for rigorous experimental methodology using heavy stable isotope peptides spiking into the immunoaffinity-purified mixtures of natural MHC peptides and analysis by the highly reliable targeted MS, to claim that MHC peptides are indeed spliced. Peptide splicing was suggested to contribute to the immunopeptidome. I suggest that this idea should be reconsidered based on new evidences. Both biochemical and bioinformatics considerations argue against peptide splicing.
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Affiliation(s)
- Arie Admon
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
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14
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ROS Cocktails as an Adjuvant for Personalized Antitumor Vaccination? Vaccines (Basel) 2021; 9:vaccines9050527. [PMID: 34069708 PMCID: PMC8161309 DOI: 10.3390/vaccines9050527] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/15/2021] [Accepted: 05/17/2021] [Indexed: 12/22/2022] Open
Abstract
Cancer is the second leading cause of death worldwide. Today, the critical role of the immune system in tumor control is undisputed. Checkpoint antibody immunotherapy augments existing antitumor T cell activity with durable clinical responses in many tumor entities. Despite the presence of tumor-associated antigens and neoantigens, many patients have an insufficient repertoires of antitumor T cells. Autologous tumor vaccinations aim at alleviating this defect, but clinical success is modest. Loading tumor material into autologous dendritic cells followed by their laboratory expansion and therapeutic vaccination is promising, both conceptually and clinically. However, this process is laborious, time-consuming, costly, and hence less likely to solve the global cancer crisis. Therefore, it is proposed to re-focus on personalized anticancer vaccinations to enhance the immunogenicity of autologous therapeutic tumor vaccines. Recent work re-established the idea of using the alarming agents of the immune system, oxidative modifications, as an intrinsic adjuvant to broaden the antitumor T cell receptor repertoire in cancer patients. The key novelty is the use of gas plasma, a multi-reactive oxygen and nitrogen species-generating technology, for diversifying oxidative protein modifications in a, so far, unparalleled manner. This significant innovation has been successfully used in proof-of-concept studies and awaits broader recognition and implementation to explore its chances and limitations of providing affordable personalized anticancer vaccines in the future. Such multidisciplinary advance is timely, as the current COVID-19 crisis is inexorably reflecting the utmost importance of innovative and effective vaccinations in modern times.
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Carré A, Mallone R. Making Insulin and Staying Out of Autoimmune Trouble: The Beta-Cell Conundrum. Front Immunol 2021; 12:639682. [PMID: 33854508 PMCID: PMC8039383 DOI: 10.3389/fimmu.2021.639682] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/12/2021] [Indexed: 12/28/2022] Open
Abstract
Autoimmune type 1 diabetes (T1D) results from the intricate crosstalk of various immune cell types. CD8+ T cells dominate the pro-inflammatory milieu of islet infiltration (insulitis), and are considered as key effectors of beta-cell destruction, through the recognition of MHC Class I-peptide complexes. The pathways generating MHC Class I-restricted antigens in beta cells are poorly documented. Given their specialized insulin secretory function, the associated granule processing and degradation pathways, basal endoplasmic reticulum stress and susceptibility to additional stressors, alternative antigen processing and presentation (APP) pathways are likely to play a significant role in the generation of the beta-cell immunopeptidome. As direct evidence is missing, we here intersect the specificities of beta-cell function and the literature about APP in other cellular models to generate some hypotheses on APPs relevant to beta cells. We further elaborate on the potential role of these pathways in T1D pathogenesis, based on the current knowledge of antigens presented by beta cells. A better understanding of these pathways may pinpoint novel mechanisms amenable to therapeutic targeting to modulate the immunogenicity of beta cells.
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Affiliation(s)
- Alexia Carré
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France
| | - Roberto Mallone
- Université de Paris, Institut Cochin, CNRS, INSERM, Paris, France.,Assistance Publique Hôpitaux de Paris, Service de Diabétologie et Immunologie Clinique, Cochin Hospital, Paris, France
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16
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Kasahara M. Role of immunoproteasomes and thymoproteasomes in health and disease. Pathol Int 2021; 71:371-382. [PMID: 33657242 DOI: 10.1111/pin.13088] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/11/2021] [Indexed: 12/14/2022]
Abstract
The proteasome is a multisubunit protease that degrades intracellular proteins into small peptides. Besides playing a pivotal role in many cellular processes indispensable for survival, it is involved in the production of peptides presented by major histocompatibility complex class I molecules. In addition to the standard proteasome shared in all eukaryotes, jawed vertebrates have two specialized forms of proteasome known as immunoproteasomes and thymoproteasomes. The immunoproteasome, which contains cytokine-inducible catalytic subunits with distinct cleavage specificities, produces peptides presented by class I molecules more efficiently than the standard proteasome. The thymoproteasome, which contains a unique catalytic subunit β5t, is a tissue-specific proteasome expressed exclusively in cortical thymic epithelial cells. It plays a critical role in CD8+ cytotoxic T cell development via positive selection. This review provides a brief overview on the structure and function of these specialized forms of proteasome and their involvement in human disease.
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Affiliation(s)
- Masanori Kasahara
- Department of Pathology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Hokkaido, Japan
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17
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Mansurkhodzhaev A, Barbosa CRR, Mishto M, Liepe J. Proteasome-Generated cis-Spliced Peptides and Their Potential Role in CD8 + T Cell Tolerance. Front Immunol 2021; 12:614276. [PMID: 33717099 PMCID: PMC7943738 DOI: 10.3389/fimmu.2021.614276] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/28/2021] [Indexed: 01/09/2023] Open
Abstract
The human immune system relies on the capability of CD8+ T cells to patrol body cells, spot infected cells and eliminate them. This cytotoxic response is supposed to be limited to infected cells to avoid killing of healthy cells. To enable this, CD8+ T cells have T Cell Receptors (TCRs) which should discriminate between self and non-self through the recognition of antigenic peptides bound to Human Leukocyte Antigen class I (HLA-I) complexes-i.e., HLA-I immunopeptidomes-of patrolled cells. The majority of these antigenic peptides are produced by proteasomes through either peptide hydrolysis or peptide splicing. Proteasome-generated cis-spliced peptides derive from a given antigen, are immunogenic and frequently presented by HLA-I complexes. Theoretically, they also have a very large sequence variability, which might impinge upon our model of self/non-self discrimination and central and peripheral CD8+ T cell tolerance. Indeed, a large variety of cis-spliced epitopes might enlarge the pool of viral-human zwitter epitopes, i.e., peptides that may be generated with the exact same sequence from both self (human) and non-self (viral) antigens. Antigenic viral-human zwitter peptides may be recognized by CD8+ thymocytes and T cells, induce clonal deletion or other tolerance processes, thereby restraining CD8+ T cell response against viruses. To test this hypothesis, we computed in silico the theoretical frequency of zwitter non-spliced and cis-spliced epitope candidates derived from human proteome (self) and from the proteomes of a large pool of viruses (non-self). We considered their binding affinity to the representative HLA-A*02:01 complex, self-antigen expression in Medullary Thymic Epithelial cells (mTECs) and the relative frequency of non-spliced and cis-spliced peptides in HLA-I immunopeptidomes. Based on the present knowledge of proteasome-catalyzed peptide splicing and neglecting CD8+ TCR degeneracy, our study suggests that, despite their frequency, the portion of the cis-spliced peptides we investigated could only marginally impinge upon the variety of functional CD8+ cytotoxic T cells (CTLs) involved in anti-viral response.
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Affiliation(s)
- Artem Mansurkhodzhaev
- Quantitative and Systems Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Camila R. R. Barbosa
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) and Peter Gorer Department of Immunobiology, King's College London, London, United Kingdom
| | - Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) and Peter Gorer Department of Immunobiology, King's College London, London, United Kingdom
- Francis Crick Institute, London, United Kingdom
| | - Juliane Liepe
- Quantitative and Systems Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
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18
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Gomez-Perosanz M, Ras-Carmona A, Lafuente EM, Reche PA. Identification of CD8 + T cell epitopes through proteasome cleavage site predictions. BMC Bioinformatics 2020; 21:484. [PMID: 33308150 PMCID: PMC7733697 DOI: 10.1186/s12859-020-03782-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 09/28/2020] [Indexed: 01/08/2023] Open
Abstract
Background We previously introduced PCPS (Proteasome Cleavage Prediction Server), a web-based tool to predict proteasome cleavage sites using n-grams. Here, we evaluated the ability of PCPS immunoproteasome cleavage model to discriminate CD8+ T cell epitopes. Results We first assembled an epitope dataset consisting of 844 unique virus-specific CD8+ T cell epitopes and their source proteins. We then analyzed cleavage predictions by PCPS immunoproteasome cleavage model on this dataset and compared them with those provided by a related method implemented by NetChop web server. PCPS was clearly superior to NetChop in term of sensitivity (0.89 vs. 0.79) but somewhat inferior with regard to specificity (0.55 vs. 0.60). Judging by the Mathew’s Correlation Coefficient, PCPS predictions were overall superior to those provided by NetChop (0.46 vs. 0.39). We next analyzed the power of C-terminal cleavage predictions provided by the same PCPS model to discriminate CD8+ T cell epitopes, finding that they could be discriminated from random peptides with an accuracy of 0.74. Following these results, we tuned the PCPS web server to predict CD8+ T cell epitopes and predicted the entire SARS-CoV-2 epitope space. Conclusions We report an improved version of PCPS named iPCPS for predicting proteasome cleavage sites and peptides with CD8+ T cell epitope features. iPCPS is available for free public use at https://imed.med.ucm.es/Tools/pcps/.
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Affiliation(s)
- Marta Gomez-Perosanz
- Laboratory of Immunomedicine, Department of Immunology, Faculty of Medicine, Complutense University of Madrid, Pza Ramon y Cajal, s/n, 28040, Madrid, Spain
| | - Alvaro Ras-Carmona
- Laboratory of Immunomedicine, Department of Immunology, Faculty of Medicine, Complutense University of Madrid, Pza Ramon y Cajal, s/n, 28040, Madrid, Spain
| | - Esther M Lafuente
- Laboratory of Immunomedicine, Department of Immunology, Faculty of Medicine, Complutense University of Madrid, Pza Ramon y Cajal, s/n, 28040, Madrid, Spain
| | - Pedro A Reche
- Laboratory of Immunomedicine, Department of Immunology, Faculty of Medicine, Complutense University of Madrid, Pza Ramon y Cajal, s/n, 28040, Madrid, Spain.
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19
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Specht G, Roetschke HP, Mansurkhodzhaev A, Henklein P, Textoris-Taube K, Urlaub H, Mishto M, Liepe J. Large database for the analysis and prediction of spliced and non-spliced peptide generation by proteasomes. Sci Data 2020; 7:146. [PMID: 32415162 PMCID: PMC7228940 DOI: 10.1038/s41597-020-0487-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/16/2020] [Indexed: 11/10/2022] Open
Abstract
Proteasomes are the main producers of antigenic peptides presented to CD8+ T cells. They can cut proteins and release their fragments or recombine non-contiguous fragments thereby generating novel sequences, i.e. spliced peptides. Understanding which are the driving forces and the sequence preferences of both reactions can streamline target discovery in immunotherapies against cancer, infection and autoimmunity. Here, we present a large database of spliced and non-spliced peptides generated by proteasomes in vitro, which is available as simple CSV file and as a MySQL database. To generate the database, we performed in vitro digestions of 55 unique synthetic polypeptide substrates with different proteasome isoforms and experimental conditions. We measured the samples using three mass spectrometers, filtered and validated putative peptides, identified 22,333 peptide product sequences (15,028 spliced and 7,305 non-spliced product sequences). Our database and datasets have been deposited to the Mendeley (doi:10.17632/nr7cs764rc.1) and PRIDE (PXD016782) repositories. We anticipate that this unique database can be a valuable source for predictors of proteasome-catalyzed peptide hydrolysis and splicing, with various future translational applications.
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Affiliation(s)
- Gerd Specht
- Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany
| | - Hanna P Roetschke
- Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany
| | | | - Petra Henklein
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Biochemistry, D-10117, Berlin, Germany
| | - Kathrin Textoris-Taube
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Shared Facility for Mass Spectrometry, D-10117, Berlin, Germany
| | - Henning Urlaub
- Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany
| | - Michele Mishto
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Biochemistry, D-10117, Berlin, Germany.
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, SE1 1UL, London, United Kingdom.
| | - Juliane Liepe
- Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany.
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20
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Abstract
The proteasome complex is mainly responsible for proteolytic degradation of cytosolic proteins, generating the C-terminus of MHC I-restricted peptide ligands and CD8 T cell epitopes. Therefore, prediction of proteasomal cleavage sites is relevant for anticipating CD8 T-cell epitopes. There are two different proteasomes, the constitutive proteasome, expressed in all types of cells, and the immunoproteasome, constitutively expressed in dendritic cells. Although both proteasome forms generate peptides for presentation by MHC I molecules, the immunoproteasome is the main form involved in providing peptide fragments for priming CD8 T cells. On the contrary, the proteasome provides peptides for presentation by MHC I molecules that can be targeted by already primed CD8 T cells. Proteasome cleavage prediction server (PCPS) is a server for predicting cleavage sites generated by both the constitutive proteasome and the immunoproteasome. Here, we illustrate the usage of PCPS to predict proteasome and immunoproteasome cleavage sites and compare the results with those provided by NetChop, a related tool available online. PCPS is implemented for free public use available online at http://imed.med.ucm.es/Tools/pcps/ .
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21
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Textoris-Taube K, Cammann C, Henklein P, Topfstedt E, Ebstein F, Henze S, Liepe J, Zhao F, Schadendorf D, Dahlmann B, Uckert W, Paschen A, Mishto M, Seifert U. ER-aminopeptidase 1 determines the processing and presentation of an immunotherapy-relevant melanoma epitope. Eur J Immunol 2019; 50:270-283. [PMID: 31729751 DOI: 10.1002/eji.201948116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 08/19/2019] [Accepted: 11/13/2019] [Indexed: 01/01/2023]
Abstract
Dissecting the different steps of the processing and presentation of tumor-associated antigens is a key aspect of immunotherapies enabling to tackle the immune response evasion attempts of cancer cells. The immunodominant glycoprotein gp100209-217 epitope, which is liberated from the melanoma differentiation antigen gp100PMEL17 , is part of immunotherapy trials. By analyzing different human melanoma cell lines, we here demonstrate that a pool of N-terminal extended peptides sharing the common minimal epitope is generated by melanoma proteasome subtypes. In vitro and in cellulo experiments indicate that ER-resident aminopeptidase 1 (ERAP1)-but not ERAP2-defines the processing of this peptide pool thereby modulating the T-cell recognition of melanoma cells. By combining the outcomes of our studies and others, we can sketch the complex processing and endogenous presentation pathway of the gp100209-217 -containing epitope/peptides, which are produced by proteasomes and are translocated to the vesicular compartment through different pathways, where the precursor peptides that reach the endoplasmic reticulum are further processed by ERAP1. The latter step enhances the activation of epitope-specific T lymphocytes, which might be a target to improve the efficiency of anti-melanoma immunotherapy.
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Affiliation(s)
- Kathrin Textoris-Taube
- Shared Facility for Mass Spectrometry, Berlin Institute of Health, Institut für Biochemie, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Clemens Cammann
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Petra Henklein
- Berlin Institute of Health, Institut für Biochemie, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Eylin Topfstedt
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Frédéric Ebstein
- Berlin Institute of Health, Institut für Biochemie, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Sarah Henze
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Juliane Liepe
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Fang Zhao
- Klinik für Dermatologie, Universitätsklinikum Essen, Essen and German Cancer Consortium (DKTK), Universität Duisburg-Essen, Essen, Germany
| | - Dirk Schadendorf
- Klinik für Dermatologie, Universitätsklinikum Essen, Essen and German Cancer Consortium (DKTK), Universität Duisburg-Essen, Essen, Germany
| | - Burkhardt Dahlmann
- Berlin Institute of Health, Institut für Biochemie, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Wolfgang Uckert
- Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz Gemeinschaft, Berlin, Germany
| | - Annette Paschen
- Klinik für Dermatologie, Universitätsklinikum Essen, Essen and German Cancer Consortium (DKTK), Universität Duisburg-Essen, Essen, Germany
| | - Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, London, United Kingdom.,Centro Interdipartimentale di Ricerca sul Cancro "Giorgio Prodi", University of Bologna, Bologna, Italy
| | - Ulrike Seifert
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
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22
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Mishto M, Mansurkhodzhaev A, Ying G, Bitra A, Cordfunke RA, Henze S, Paul D, Sidney J, Urlaub H, Neefjes J, Sette A, Zajonc DM, Liepe J. An in silico-in vitro Pipeline Identifying an HLA-A *02:01 + KRAS G12V + Spliced Epitope Candidate for a Broad Tumor-Immune Response in Cancer Patients. Front Immunol 2019; 10:2572. [PMID: 31803176 PMCID: PMC6872521 DOI: 10.3389/fimmu.2019.02572] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 10/16/2019] [Indexed: 12/22/2022] Open
Abstract
Targeting CD8+ T cells to recurrent tumor-specific mutations can profoundly contribute to cancer treatment. Some of these mutations are potential tumor antigens although they can be displayed by non-spliced epitopes only in a few patients, because of the low affinity of the mutated non-spliced peptides for the predominant HLA class I alleles. Here, we describe a pipeline that uses the large sequence variety of proteasome-generated spliced peptides and identifies spliced epitope candidates, which carry the mutations and bind the predominant HLA-I alleles with high affinity. They could be used in adoptive T cell therapy and other anti-cancer immunotherapies for large cohorts of cancer patients. As a proof of principle, the application of this pipeline led to the identification of a KRAS G12V mutation-carrying spliced epitope candidate, which is produced by proteasomes, transported by TAPs and efficiently presented by the most prevalent HLA class I molecules, HLA-A*02:01 complexes.
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Affiliation(s)
- Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, London, United Kingdom.,Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institut für Biochemie, Berlin, Germany
| | - Artem Mansurkhodzhaev
- Quantitative and Systems Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ge Ying
- Division of Immune Regulation, La Jolla Institute for Allergy and Immunology, La Jolla, CA, United States
| | - Aruna Bitra
- Division of Immune Regulation, La Jolla Institute for Allergy and Immunology, La Jolla, CA, United States
| | - Robert A Cordfunke
- Department of Immunohematology and Bloodbank, Leiden University Medical Center LUMC, Leiden, Netherlands
| | - Sarah Henze
- Quantitative and Systems Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Debdas Paul
- Quantitative and Systems Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - John Sidney
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA, United States
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max-Planck-Institute for Biophysical Chemistry, Goettingen, Germany.,Institut for Clinical Chemistry, University Medical Center Goettingen Bioanalytics, Goettingen, Germany
| | - Jacques Neefjes
- Department of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center LUMC, Leiden, Netherlands
| | - Alessandro Sette
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA, United States.,Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Dirk M Zajonc
- Division of Immune Regulation, La Jolla Institute for Immunology, La Jolla, CA, United States.,Department of Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Juliane Liepe
- Quantitative and Systems Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.,Department of Life Sciences, Centre for Integrative Systems Biology and Bioinformatics, Imperial College London, London, United Kingdom
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23
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Vigneron N, Stroobant V, Ferrari V, Abi Habib J, Van den Eynde BJ. Production of spliced peptides by the proteasome. Mol Immunol 2019; 113:93-102. [DOI: 10.1016/j.molimm.2018.03.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 03/09/2018] [Accepted: 03/29/2018] [Indexed: 01/28/2023]
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24
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Morozov AV, Karpov VL. Proteasomes and Several Aspects of Their Heterogeneity Relevant to Cancer. Front Oncol 2019; 9:761. [PMID: 31456945 PMCID: PMC6700291 DOI: 10.3389/fonc.2019.00761] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 07/29/2019] [Indexed: 01/19/2023] Open
Abstract
The life of every organism is dependent on the fine-tuned mechanisms of protein synthesis and breakdown. The degradation of most intracellular proteins is performed by the ubiquitin proteasome system (UPS). Proteasomes are central elements of the UPS and represent large multisubunit protein complexes directly responsible for the protein degradation. Accumulating data indicate that there is an intriguing diversity of cellular proteasomes. Different proteasome forms, containing different subunits and attached regulators have been described. In addition, proteasomes specific for a particular tissue were identified. Cancer cells are highly dependent on the proper functioning of the UPS in general, and proteasomes in particular. At the same time, the information regarding the role of different proteasome forms in cancer is limited. This review describes the functional and structural heterogeneity of proteasomes, their association with cancer as well as several established and novel proteasome-directed therapeutic strategies.
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Affiliation(s)
- Alexey V. Morozov
- Laboratory of Regulation of Intracellular Proteolysis, W.A. Engelhardt Institute of Molecular Biology RAS, Moscow, Russia
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25
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Dianzani C, Vecchio D, Clemente N, Chiocchetti A, Martinelli Boneschi F, Galimberti D, Dianzani U, Comi C, Mishto M, Liepe J. Untangling Extracellular Proteasome-Osteopontin Circuit Dynamics in Multiple Sclerosis. Cells 2019; 8:cells8030262. [PMID: 30897778 PMCID: PMC6468732 DOI: 10.3390/cells8030262] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/14/2019] [Accepted: 03/18/2019] [Indexed: 12/12/2022] Open
Abstract
The function of proteasomes in extracellular space is still largely unknown. The extracellular proteasome-osteopontin circuit has recently been hypothesized to be part of the inflammatory machinery regulating relapse/remission phase alternation in multiple sclerosis. However, it is still unclear what dynamics there are between the different elements of the circuit, what the role of proteasome isoforms is, and whether these inflammatory circuit dynamics are associated with the clinical severity of multiple sclerosis. To shed light on these aspects of this novel inflammatory circuit, we integrated in vitro proteasome isoform data, cell chemotaxis cell culture data, and clinical data of multiple sclerosis cohorts in a coherent computational inference framework. Thereby, we modeled extracellular osteopontin-proteasome circuit dynamics during relapse/remission alternation in multiple sclerosis. Applying this computational framework to a longitudinal study on single multiple sclerosis patients suggests a complex interaction between extracellular proteasome isoforms and osteopontin with potential clinical implications.
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Affiliation(s)
- Chiara Dianzani
- Department of Drug Science and Technology, University of Turin, 10126 Torino, Italy.
| | - Domizia Vecchio
- Interdisciplinary Research Centre of Autoimmune Diseases (IRCAD), University of Piemonte Orientale, Amedeo Avogadro, 28100 Novara, Italy.
| | - Nausicaa Clemente
- Interdisciplinary Research Centre of Autoimmune Diseases (IRCAD), University of Piemonte Orientale, Amedeo Avogadro, 28100 Novara, Italy.
| | - Annalisa Chiocchetti
- Interdisciplinary Research Centre of Autoimmune Diseases (IRCAD), University of Piemonte Orientale, Amedeo Avogadro, 28100 Novara, Italy.
| | - Filippo Martinelli Boneschi
- Department of Biomedical Sciences for Health, University of Milan, 20122 Milan, Italy.
- MS Research Unit and Department of Neurology, IRCCS Policlinico San Donato, San Donato Milanese, 20097 Milan, Italy.
| | - Daniela Galimberti
- Department of Biomedical, Surgical and Dental Sciences, University of Milan, "Dino Ferrari" Centre, 20100 Milano, Italy.
- Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, 20100 Milano, Italy.
| | - Umberto Dianzani
- Interdisciplinary Research Centre of Autoimmune Diseases (IRCAD), University of Piemonte Orientale, Amedeo Avogadro, 28100 Novara, Italy.
| | - Cristoforo Comi
- Interdisciplinary Research Centre of Autoimmune Diseases (IRCAD), University of Piemonte Orientale, Amedeo Avogadro, 28100 Novara, Italy.
- Department of Translational Medicine, Section of Neurology, University of Piemonte Orientale, 28100 Novara, Italy.
| | - Michele Mishto
- Centre for Inflammation Biology and Cancer Immunology (CIBCI) & Peter Gorer Department of Immunobiology, King's College London, SE1 1UL London, UK.
- Institute for Biochemistry, Charité⁻Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institut für Biochemie, Germany, 10117 Berlin, Germany.
| | - Juliane Liepe
- Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
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Javitt A, Barnea E, Kramer MP, Wolf-Levy H, Levin Y, Admon A, Merbl Y. Pro-inflammatory Cytokines Alter the Immunopeptidome Landscape by Modulation of HLA-B Expression. Front Immunol 2019; 10:141. [PMID: 30833945 PMCID: PMC6387973 DOI: 10.3389/fimmu.2019.00141] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 01/17/2019] [Indexed: 12/18/2022] Open
Abstract
Antigen presentation on HLA molecules is a major mechanism by which the immune system monitors self and non-self-recognition. Importantly, HLA-I presentation has gained much attention through its role in eliciting anti-tumor immunity. Several determinants controlling the peptides presented on HLA have been uncovered, mainly through the study of model substrates and large-scale immunopeptidome analyses. These determinants include the relative abundances of proteins in the cell, the stability or turnover rate of these proteins and the binding affinities of a given peptide to the HLA haplotypes found in a cell. However, the regulatory principles involved in selection and regulation of specific antigens in response to tumor pro-inflammatory signals remain largely unknown. Here, we chose to examine the effect that TNFα and IFNγ stimulation may exert on the immunopeptidome landscape of lung cancer cells. We show that the expression of many of the proteins involved in the class I antigen presentation pathway are changed by pro-inflammatory cytokines. Further, we could show that increased expression of the HLA-B allomorph drives a significant change in HLA-bound antigens, independently of the significant changes observed in the cellular proteome. Finally, we observed increased HLA-B levels in correlation with tumor infiltration across the TCGA lung cancer cohorts. Taken together, our results suggest that the immunopeptidome landscape should be examined in the context of anti-tumor immunity whereby signals in the microenvironment may be critical in shaping and modulating this important aspect of host-tumor interactions.
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Affiliation(s)
- Aaron Javitt
- Department of Immunology, Weizmann Institute of ScienceRehovot, Israel
| | - Eilon Barnea
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Hila Wolf-Levy
- Department of Immunology, Weizmann Institute of ScienceRehovot, Israel
| | - Yishai Levin
- The Nancy and Stephen Grand Israel National Center for Personalized Medicine, de Botton Institute for Protein Profiling, Weizmann Institute of Science, Rehovot, Israel
| | - Arie Admon
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yifat Merbl
- Department of Immunology, Weizmann Institute of ScienceRehovot, Israel
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27
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Morozov AV, Karpov VL. Biological consequences of structural and functional proteasome diversity. Heliyon 2018; 4:e00894. [PMID: 30417153 PMCID: PMC6218844 DOI: 10.1016/j.heliyon.2018.e00894] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/25/2018] [Accepted: 10/24/2018] [Indexed: 12/21/2022] Open
Abstract
Cell homeostasis and regulation of metabolic pathways are ensured by synthesis, proper folding and efficient degradation of a vast amount of proteins. Ubiquitin-proteasome system (UPS) degrades most intracellular proteins and thus, participates in regulation of cellular metabolism. Within the UPS, proteasomes are the elements that perform substrate cleavage. However, the proteasomes in the organism are diverse. Structurally different proteasomes are present not only in different types of cells, but also in a single cell. The reason for proteasome heterogeneity is not fully understood. This review briefly encompasses mammalian proteasome structure and function, and discusses biological relevance of proteasome diversity for a range of important cellular functions including internal and external signaling.
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Affiliation(s)
- Alexey V Morozov
- W.A. Engelhardt Institute of Molecular Biology, RAS, 119991, Moscow, Russia
| | - Vadim L Karpov
- W.A. Engelhardt Institute of Molecular Biology, RAS, 119991, Moscow, Russia
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28
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The immunoproteasome and thymoproteasome: functions, evolution and human disease. Nat Immunol 2018; 19:923-931. [PMID: 30104634 DOI: 10.1038/s41590-018-0186-z] [Citation(s) in RCA: 198] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 07/12/2018] [Accepted: 07/19/2018] [Indexed: 01/12/2023]
Abstract
The basic principle of adaptive immunity is to strictly discriminate between self and non-self, and a central challenge to overcome is the enormous variety of pathogens that might be encountered. In cell-mediated immunity, immunological discernment takes place at a molecular or cellular level. Central to both mechanisms of discernment is the generation of antigenic peptides associated with MHC class I molecules, which is achieved by a proteolytic complex called the proteasome. To adequately accomplish the discrimination between self and non-self that is essential for adaptive immunity and self-tolerance, two proteasome subtypes have evolved via gene duplication: the immunoproteasome and the thymoproteasome. In this Review, we describe various aspects of these immunity-dedicated proteasomes, from their discovery to recent findings.
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29
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Why do proteases mess up with antigen presentation by re-shuffling antigen sequences? Curr Opin Immunol 2018; 52:81-86. [PMID: 29723668 DOI: 10.1016/j.coi.2018.04.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 04/17/2018] [Indexed: 12/27/2022]
Abstract
The sequence of a large number of MHC-presented epitopes is not present as such in the original antigen because it has been re-shuffled by the proteasome or other proteases. Why do proteases throw a spanner in the works of our model of antigen tagging and immune recognition? We describe in this review what we know about the immunological relevance of post-translationally spliced epitopes and why proteases seem to have a second (dark) personality, which is keen to create new peptide bonds.
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30
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Cosma G, Eisenlohr L. CD8 + T-cell responses in vaccination: reconsidering targets and function in the context of chronic antigen stimulation. F1000Res 2018; 7. [PMID: 29770202 PMCID: PMC5931265 DOI: 10.12688/f1000research.14115.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/20/2018] [Indexed: 12/23/2022] Open
Abstract
Cytotoxic CD8 T cells play important roles in eliminating infected and transformed cells. Owing to their potential for therapeutic applications, significant efforts are dedicated toward developing CD8 T cell–based vaccines. Thus far, CD8 T-cell vaccination strategies have had limited success therapeutically in contrast to those targeting antibody-based immunity. However, if the current challenges and gaps in the understanding of T-cell biology are overcome, the full potential of rational CD8 T-cell vaccine design might be realized. Here, we review recent progress in this direction, focusing on target selection and maintenance of function in the settings of chronic infections and cancers.
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Affiliation(s)
- Gabriela Cosma
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Laurence Eisenlohr
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA, USA
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31
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Mannering SI, So M, Elso CM, Kay TWH. Shuffling peptides to create T-cell epitopes: does the immune system play cards? Immunol Cell Biol 2017; 96:34-40. [PMID: 29359347 DOI: 10.1111/imcb.1015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 09/17/2017] [Accepted: 09/18/2017] [Indexed: 11/27/2022]
Abstract
For a long time, immunologists have believed that classical CD4+ and CD8+ T cells recognize peptides (referred to as epitopes), derived from protein antigens presented by MHC/HLA class I or II. Over the past 10-15 years, it has become clear that epitopes recognized by CD8+, and more recently CD4+ T cells, can be formed by protein splicing. Here, we review the discovery of spliced epitopes recognized by tumor-specific human CD8+ T cells. We discuss how these epitopes are formed and some of the unusual variants that have been reported. Now, over a decade since the first report, evidence is emerging that spliced CD8+ T-cell epitopes are much more common, and potentially much more important, than previously imagined. Recent work has shown that epitopes recognized by CD4+ T cells can also be formed by protein splicing. We discuss the recent discovery of spliced CD4+ T-cell epitopes and their potential role as targets of autoimmune T-cell responses. Finally, we highlight some of the new questions raised from our growing appreciation of T-cell epitopes formed by peptide splicing.
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Affiliation(s)
- Stuart I Mannering
- Immunology and Diabetes Unit, St. Vincent's Institute of Medical Research, Fitzroy, Vic., Australia
| | - Michelle So
- Immunology and Diabetes Unit, St. Vincent's Institute of Medical Research, Fitzroy, Vic., Australia
| | - Colleen M Elso
- Immunology and Diabetes Unit, St. Vincent's Institute of Medical Research, Fitzroy, Vic., Australia
| | - Thomas W H Kay
- Immunology and Diabetes Unit, St. Vincent's Institute of Medical Research, Fitzroy, Vic., Australia
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32
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Vigneron N, Ferrari V, Stroobant V, Abi Habib J, Van den Eynde BJ. Peptide splicing by the proteasome. J Biol Chem 2017; 292:21170-21179. [PMID: 29109146 DOI: 10.1074/jbc.r117.807560] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The proteasome is the major protease responsible for the production of antigenic peptides recognized by CD8+ cytolytic T cells (CTL). These peptides, generally 8-10 amino acids long, are presented at the cell surface by major histocompatibility complex (MHC) class I molecules. Originally, these peptides were believed to be solely derived from linear fragments of proteins, but this concept was challenged several years ago by the isolation of anti-tumor CTL that recognized spliced peptides, i.e. peptides composed of fragments distant in the parental protein. The splicing process was shown to occur in the proteasome through a transpeptidation reaction involving an acyl-enzyme intermediate. Here, we review the steps that led to the discovery of spliced peptides as well as the recent advances that uncover the unexpected importance of spliced peptides in the composition of the MHC class I repertoire.
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Affiliation(s)
- Nathalie Vigneron
- From the Ludwig Institute for Cancer Research.,the de Duve Institute, Université catholique de Louvain, and
| | - Violette Ferrari
- From the Ludwig Institute for Cancer Research.,the de Duve Institute, Université catholique de Louvain, and
| | - Vincent Stroobant
- From the Ludwig Institute for Cancer Research.,the de Duve Institute, Université catholique de Louvain, and
| | - Joanna Abi Habib
- From the Ludwig Institute for Cancer Research.,the de Duve Institute, Université catholique de Louvain, and
| | - Benoit J Van den Eynde
- From the Ludwig Institute for Cancer Research, .,the de Duve Institute, Université catholique de Louvain, and.,WELBIO (Walloon Excellence in Life Sciences and Biotechnology), B-1200 Brussels, Belgium
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33
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Vigneron N, Abi Habib J, Van den Eynde BJ. Learning from the Proteasome How To Fine-Tune Cancer Immunotherapy. Trends Cancer 2017; 3:726-741. [PMID: 28958390 DOI: 10.1016/j.trecan.2017.07.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/20/2017] [Accepted: 07/24/2017] [Indexed: 10/19/2022]
Abstract
Cancer immunotherapy has recently emerged as a forefront strategy to fight cancer. Key players in antitumor responses are CD8+ cytolytic T lymphocytes (CTLs) that can detect tumor cells that carry antigens, in other words, small peptides bound to surface major histocompatibility complex (MHC) class I molecules. The success and safety of cancer immunotherapy strategies depends on the nature of the antigens recognized by the targeted T cells, their strict tumor specificity, and whether tumors and antigen-presenting cells can efficiently process the peptide. We review here the nature of the tumor antigens and their potential for the development of immunotherapeutic strategies. We also discuss the importance of proteasome in the production of these peptides in the context of immunotherapy and therapeutic cancer vaccines.
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Affiliation(s)
- Nathalie Vigneron
- Ludwig Institute for Cancer Research, Brussels, Belgium; de Duve Institute, Université Catholique de Louvain, Brussels, Belgium.
| | - Joanna Abi Habib
- Ludwig Institute for Cancer Research, Brussels, Belgium; de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Benoit J Van den Eynde
- Ludwig Institute for Cancer Research, Brussels, Belgium; de Duve Institute, Université Catholique de Louvain, Brussels, Belgium; WELBIO (Walloon Excellence in Life Sciences and Biotechnology), Brussels, Belgium
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34
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Post-Translational Peptide Splicing and T Cell Responses. Trends Immunol 2017; 38:904-915. [PMID: 28830734 DOI: 10.1016/j.it.2017.07.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 07/10/2017] [Accepted: 07/26/2017] [Indexed: 12/21/2022]
Abstract
CD8+ T cell specificity depends on the recognition of MHC class I-epitope complexes at the cell surface. These epitopes are mainly produced via degradation of proteins by the proteasome, generating fragments of the original sequence. However, it is now clear that proteasomes can produce a significant portion of epitopes by reshuffling the antigen sequence, thus expanding the potential antigenic repertoire. MHC class I-restricted spliced epitopes have been described in tumors and infections, suggesting an unpredicted relevance of these peculiar peptides. We review current knowledge about proteasome-catalyzed peptide splicing (PCPS), the emerging rules governing this process, and the potential implications for our understanding and therapeutic use of CD8+ T cells, as well as mechanisms generating other non-canonical antigenic epitopes targeted by the T cell response.
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35
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Roep BO, Kracht MJ, van Lummel M, Zaldumbide A. A roadmap of the generation of neoantigens as targets of the immune system in type 1 diabetes. Curr Opin Immunol 2016; 43:67-73. [PMID: 27723537 DOI: 10.1016/j.coi.2016.09.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 08/16/2016] [Accepted: 09/28/2016] [Indexed: 01/08/2023]
Abstract
Type 1 diabetes (T1D) is an autoimmune disease characterized by the selective destruction of the insulin-producing beta cells. Beta cell dysfunction caused by an inflammatory microenvironment is believed to trigger the peripheral activation of CD4 and CD8 autoreactive T cells. This review will compile post-transcriptional and post-translational modifications (PTM) involved in the generation of beta cell neoantigens and proposes a reconstruction of the sequence of events connecting environmental changes and autoimmunity.
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Affiliation(s)
- Bart O Roep
- Department of Diabetes Immunology, Diabetes and Metabolism Research Institute at the Beckman Research Institute of the City of Hope, Duarte, CA, USA; Department of Immunohematology & Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands.
| | - Maria Jl Kracht
- Department of Immunohematology & Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands; Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Menno van Lummel
- Department of Immunohematology & Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
| | - Arnaud Zaldumbide
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
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36
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Platteel ACM, Mishto M, Textoris-Taube K, Keller C, Liepe J, Busch DH, Kloetzel PM, Sijts AJAM. CD8(+) T cells of Listeria monocytogenes-infected mice recognize both linear and spliced proteasome products. Eur J Immunol 2016; 46:1109-18. [PMID: 26909514 DOI: 10.1002/eji.201545989] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 01/25/2016] [Accepted: 02/17/2016] [Indexed: 02/05/2023]
Abstract
CD8(+) T cells responding to infection recognize pathogen-derived epitopes presented by MHC class-I molecules. While most of such epitopes are generated by proteasome-mediated antigen cleavage, analysis of tumor antigen processing has revealed that epitopes may also derive from proteasome-catalyzed peptide splicing (PCPS). To determine whether PCPS contributes to epitope processing during infection, we analyzed the fragments produced by purified proteasomes from a Listeria monocytogenes polypeptide. Mass spectrometry identified a known H-2K(b) -presented linear epitope (LLO296-304 ) in the digests, as well as four spliced peptides that were trimmed by ERAP into peptides with in silico predicted H-2K(b) binding affinity. These spliced peptides, which displayed sequence similarity with LLO296-304 , bound to H-2K(b) molecules in cellular assays and one of the peptides was recognized by CD8(+) T cells of infected mice. This spliced epitope differed by one amino acid from LLO296-304 and double staining with LLO296-304 - and spliced peptide-folded MHC multimers showed that LLO296-304 and its spliced variant were recognized by the same CD8(+) T cells. Thus, PCPS multiplies the variety of peptides that is processed from an antigen and leads to the production of epitope variants that can be recognized by cross-reacting pathogen-specific CD8(+) T cells. Such mechanism may reduce the chances for pathogen immune evasion.
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Affiliation(s)
- Anouk C M Platteel
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Michele Mishto
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Interdepartmental Centre "Luigi Galvani" for Bioinformatics, Biophysics and Biocomplexity (CIG), Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | | | - Christin Keller
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Juliane Liepe
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, UK
| | - Dirk H Busch
- Institute for Medical Microbiology, Immunology and Hygiene, TU Munich, Munich, Germany
| | - Peter M Kloetzel
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Alice J A M Sijts
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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37
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Textoris-Taube K, Keller C, Liepe J, Henklein P, Sidney J, Sette A, Kloetzel PM, Mishto M. The T210M Substitution in the HLA-a*02:01 gp100 Epitope Strongly Affects Overall Proteasomal Cleavage Site Usage and Antigen Processing. J Biol Chem 2015; 290:30417-28. [PMID: 26507656 DOI: 10.1074/jbc.m115.695189] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Indexed: 01/01/2023] Open
Abstract
MHC class I-restricted epitopes, which carry a tumor-specific mutation resulting in improved MHC binding affinity, are preferred T cell receptor targets in innovative adoptive T cell therapies. However, T cell therapy requires efficient generation of the selected epitope. How such mutations may affect proteasome-mediated antigen processing has so far not been studied. Therefore, we analyzed by in vitro experiments the effect on antigen processing and recognition of a T210M exchange, which previously had been introduced into the melanoma gp100209-217 tumor epitope to improve the HLA-A*02:01 binding and its immunogenicity. A quantitative analysis of the main steps of antigen processing shows that the T210M exchange affects proteasomal cleavage site usage within the mutgp100201-230 polypeptide, leading to the generation of an unique set of cleavage products. The T210M substitution qualitatively affects the proteasome-catalyzed generation of spliced and non-spliced peptides predicted to bind HLA-A or -B complexes. The T210M substitution also induces an enhanced production of the mutgp100209-217 epitope and its N-terminally extended peptides. The T210M exchange revealed no effect on ERAP1-mediated N-terminal trimming of the precursor peptides. However, mutant N-terminally extended peptides exhibited significantly increased HLA-A*02:01 binding affinity and elicited CD8(+) T cell stimulation in vitro similar to the wtgp100209-217 epitope. Thus, our experiments demonstrate that amino acid exchanges within an epitope can result in the generation of an altered peptide pool with new antigenic peptides and in a wider CD8(+) T cell response also towards N-terminally extended versions of the minimal epitope.
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Affiliation(s)
- Kathrin Textoris-Taube
- From the Institut für Biochemie, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Christin Keller
- From the Institut für Biochemie, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Juliane Liepe
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, SW7 2AZ, United Kingdom, and
| | - Petra Henklein
- From the Institut für Biochemie, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - John Sidney
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037
| | - Alessandro Sette
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037
| | - Peter M Kloetzel
- From the Institut für Biochemie, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany,
| | - Michele Mishto
- From the Institut für Biochemie, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany,
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38
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Zhang MZ, Guo QH, Sheng WB, Guo CC. Potassiumtert-Butoxide-Mediated Amine Acyl Exchange Reaction ofN,N-Disubstituted Formamides with Aromatic Carbonyl DerivativesviaSequential CN Bond Cleavage/Formation: an Approach to Aromatic Amides. Adv Synth Catal 2015. [DOI: 10.1002/adsc.201500551] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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39
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Human Tumor Antigens and Cancer Immunotherapy. BIOMED RESEARCH INTERNATIONAL 2015; 2015:948501. [PMID: 26161423 PMCID: PMC4487697 DOI: 10.1155/2015/948501] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 03/03/2015] [Indexed: 01/21/2023]
Abstract
With the recent developments of adoptive T cell therapies and the use of new monoclonal antibodies against the immune checkpoints, immunotherapy is at a turning point. Key players for the success of these therapies are the cytolytic T lymphocytes, which are a subset of T cells able to recognize and kill tumor cells. Here, I review the nature of the antigenic peptides recognized by these T cells and the processes involved in their presentation. I discuss the importance of understanding how each antigenic peptide is processed in the context of immunotherapy and vaccine delivery.
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40
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Proteasome subtypes and regulators in the processing of antigenic peptides presented by class I molecules of the major histocompatibility complex. Biomolecules 2014; 4:994-1025. [PMID: 25412285 PMCID: PMC4279167 DOI: 10.3390/biom4040994] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/02/2014] [Accepted: 10/29/2014] [Indexed: 02/07/2023] Open
Abstract
The proteasome is responsible for the breakdown of cellular proteins. Proteins targeted for degradation are allowed inside the proteasome particle, where they are cleaved into small peptides and released in the cytosol to be degraded into amino acids. In vertebrates, some of these peptides escape degradation in the cytosol, are loaded onto class I molecules of the major histocompatibility complex (MHC) and displayed at the cell surface for scrutiny by the immune system. The proteasome therefore plays a key role for the immune system: it provides a continued sampling of intracellular proteins, so that CD8-positive T-lymphocytes can kill cells expressing viral or tumoral proteins. Consequently, the repertoire of peptides displayed by MHC class I molecules at the cell surface depends on proteasome activity, which may vary according to the presence of proteasome subtypes and regulators. Besides standard proteasomes, cells may contain immunoproteasomes, intermediate proteasomes and thymoproteasomes. Cells may also contain regulators of proteasome activity, such as the 19S, PA28 and PA200 regulators. Here, we review the effects of these proteasome subtypes and regulators on the production of antigenic peptides. We also discuss an unexpected function of the proteasome discovered through the study of antigenic peptides: its ability to splice peptides.
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41
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de Verteuil DA, Rouette A, Hardy MP, Lavallée S, Trofimov A, Gaucher É, Perreault C. Immunoproteasomes Shape the Transcriptome and Regulate the Function of Dendritic Cells. THE JOURNAL OF IMMUNOLOGY 2014; 193:1121-32. [DOI: 10.4049/jimmunol.1400871] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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42
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Liepe J, Holzhütter HG, Kloetzel PM, Stumpf MPH, Mishto M. Modelling proteasome and proteasome regulator activities. Biomolecules 2014; 4:585-99. [PMID: 24970232 PMCID: PMC4101499 DOI: 10.3390/biom4020585] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/28/2014] [Accepted: 05/30/2014] [Indexed: 02/07/2023] Open
Abstract
Proteasomes are key proteases involved in a variety of processes ranging from the clearance of damaged proteins to the presentation of antigens to CD8+ T-lymphocytes. Which cleavage sites are used within the target proteins and how fast these proteins are degraded have a profound impact on immune system function and many cellular metabolic processes. The regulation of proteasome activity involves different mechanisms, such as the substitution of the catalytic subunits, the binding of regulatory complexes to proteasome gates and the proteasome conformational modifications triggered by the target protein itself. Mathematical models are invaluable in the analysis; and potentially allow us to predict the complex interactions of proteasome regulatory mechanisms and the final outcomes of the protein degradation rate and MHC class I epitope generation. The pioneering attempts that have been made to mathematically model proteasome activity, cleavage preference variation and their modification by one of the regulatory mechanisms are reviewed here.
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Affiliation(s)
- Juliane Liepe
- Theoretical Systems Biology, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK.
| | | | - Peter M Kloetzel
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany.
| | - Michael P H Stumpf
- Theoretical Systems Biology, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK.
| | - Michele Mishto
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany.
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43
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Grignolio A, Mishto M, Faria AMC, Garagnani P, Franceschi C, Tieri P. Towards a liquid self: how time, geography, and life experiences reshape the biological identity. Front Immunol 2014; 5:153. [PMID: 24782860 PMCID: PMC3988364 DOI: 10.3389/fimmu.2014.00153] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 03/24/2014] [Indexed: 01/08/2023] Open
Abstract
The conceptualization of immunological self is amongst the most important theories of modern biology, representing a sort of theoretical guideline for experimental immunologists, in order to understand how host constituents are ignored by the immune system (IS). A consistent advancement in this field has been represented by the danger/damage theory and its subsequent refinements, which at present represents the most comprehensive conceptualization of immunological self. Here, we present the new hypothesis of "liquid self," which integrates and extends the danger/damage theory. The main novelty of the liquid self hypothesis lies in the full integration of the immune response mechanisms into the host body's ecosystems, i.e., in adding the temporal, as well as the geographical/evolutionary and environmental, dimensions, which we suggested to call "immunological biography." Our hypothesis takes into account the important biological changes occurring with time (age) in the IS (including immunosenescence and inflammaging), as well as changes in the organismal context related to nutrition, lifestyle, and geography (populations). We argue that such temporal and geographical dimensions impinge upon, and continuously reshape, the antigenicity of physical entities (molecules, cells, bacteria, viruses), making them switching between "self" and "non-self" states in a dynamical, "liquid" fashion. Particular attention is devoted to oral tolerance and gut microbiota, as well as to a new potential source of unexpected self epitopes produced by proteasome splicing. Finally, our framework allows the set up of a variety of testable predictions, the most straightforward suggesting that the immune responses to defined molecules representing potentials antigens will be quantitatively and qualitatively quite different according to the immuno-biographical background of the host.
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Affiliation(s)
- Andrea Grignolio
- Interdepartmental Center "Luigi Galvani" for Bioinformatics, Biophysics and Biocomplexity, University of Bologna , Bologna , Italy
| | - Michele Mishto
- Centro Interdipartimentale di Ricerca sul Cancro "G. Prodi", University of Bologna , Bologna , Italy ; Institut für Biochemie, Charité - Universitätsmedizin Berlin , Berlin , Germany
| | - Ana Maria Caetano Faria
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais , Belo Horizonte , Brazil
| | - Paolo Garagnani
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna , Bologna , Italy
| | - Claudio Franceschi
- Interdepartmental Center "Luigi Galvani" for Bioinformatics, Biophysics and Biocomplexity, University of Bologna , Bologna , Italy ; Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna , Bologna , Italy ; IRCCS of Neurological Science , Bologna , Italy ; Institute of Organic Synthesis and Photoreactivity, National Research Council , Bologna , Italy
| | - Paolo Tieri
- Institute for Applied Mathematics "M. Picone", National Research Council , Rome , Italy
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Ferrington DA, Gregerson DS. Immunoproteasomes: structure, function, and antigen presentation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 109:75-112. [PMID: 22727420 DOI: 10.1016/b978-0-12-397863-9.00003-1] [Citation(s) in RCA: 256] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Immunoproteasomes contain replacements for the three catalytic subunits of standard proteasomes. In most cells, oxidative stress and proinflammatory cytokines are stimuli that lead to elevated production of immunoproteasomes. Immune system cells, especially antigen-presenting cells, express a higher basal level of immunoproteasomes. A well-described function of immunoproteasomes is to generate peptides with a hydrophobic C terminus that can be processed to fit in the groove of MHC class I molecules. This display of peptides on the cell surface allows surveillance by CD8 T cells of the adaptive immune system for pathogen-infected cells. Functions of immunoproteasomes, other than generating peptides for antigen presentation, are emerging from studies in immunoproteasome-deficient mice, and are complemented by recently described diseases linked to mutations or single-nucleotide polymorphisms in immunoproteasome subunits. Thus, this growing body of literature suggests a more pleiotropic role in cell function for the immunoproteasome.
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Affiliation(s)
- Deborah A Ferrington
- Department of Ophthalmology, University of Minnesota, Minneapolis, Minnesota, USA
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Eleftheriadis T, Pissas G, Antoniadi G, Liakopoulos V, Stefanidis I. CD8+ T-cell auto-reactivity is dependent on the expression of the immunoproteasome subunit LMP7 in exposed to lipopolysaccharide antigen presenting cells and epithelial target cells. Autoimmunity 2013; 46:439-45. [DOI: 10.3109/08916934.2013.801460] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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46
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Castangia R, Austeri M, Flitsch SL. Enzymatic Amine Acyl Exchange in Peptides on Gold Surfaces. Angew Chem Int Ed Engl 2012; 51:13016-8. [DOI: 10.1002/anie.201205404] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/30/2012] [Indexed: 11/09/2022]
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47
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Castangia R, Austeri M, Flitsch SL. Enzymatischer Amin-Acyl-Austausch in Peptiden auf Gold-Oberflächen. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205404] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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48
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Vigneron N, Van den Eynde BJ. Proteasome subtypes and the processing of tumor antigens: increasing antigenic diversity. Curr Opin Immunol 2011; 24:84-91. [PMID: 22206698 DOI: 10.1016/j.coi.2011.12.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 12/07/2011] [Indexed: 11/25/2022]
Abstract
Protein degradation by the proteasome releases peptides that can be loaded on MHC class I molecules and presented to cytolytic T lymphocytes. Several mechanisms were recently found to increase the diversity of antigenic peptides displayed at the cell surface, thereby maximizing the efficacy of immune responses. The proteasome was shown to produce spliced antigenic peptides, which are made of two fragments initially not contiguous in the parental protein. Different proteasome subtypes also produce distinct sets of antigenic peptides: the standard proteasome and the immunoproteasome, containing different catalytic subunits, have different cleavage specificities and produce different sets of peptides. Moreover, recent work confirmed the existence of two additional proteasome subtypes that are intermediate between the standard and the immunoproteasome, and each produce a unique peptide repertoire.
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Affiliation(s)
- Nathalie Vigneron
- Ludwig Institute for Cancer Research, Brussels Branch and de Duve Institute, Université catholique de Louvain, Brussels, Belgium
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49
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Origin and plasticity of MHC I-associated self peptides. Autoimmun Rev 2011; 11:627-35. [PMID: 22100331 DOI: 10.1016/j.autrev.2011.11.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 11/02/2011] [Indexed: 01/13/2023]
Abstract
Endogenous peptides presented by MHC I molecules represent the essence of self for CD8 T lymphocytes. These MHC I peptides (MIPs) regulate all key events that occur during the lifetime of CD8 T cells. CD8 T cells are selected on self-MIPs, sustained by self-MIPs, and activated in the presence of self-MIPs. Recently, large-scale mass spectrometry studies have revealed that the self-MIP repertoire is more complex and plastic than previously anticipated. The composition of the self-MIP repertoire varies from one cell type to another and can be perturbed by cell-intrinsic and -extrinsic factors including dysregulation of cellular metabolism and infection. The complexity and plasticity of the self-MIP repertoire represent a major challenge for the maintenance of self tolerance and can have pervasive effects on the global functioning of the immune system.
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Eleftheriadis T. The existence of two types of proteasome, the constitutive proteasome and the immunoproteasome, may serve as another layer of protection against autoimmunity. Med Hypotheses 2011; 78:138-41. [PMID: 22070888 DOI: 10.1016/j.mehy.2011.10.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 10/10/2011] [Indexed: 12/28/2022]
Abstract
Negative selection of CD8 single positive thymocytes is based on the presentation through the major histocompatibility complex (MHC) class I pathway of peptides derived from degradation of self-proteins by the constitutive proteasome and the immunoproteasome in the thymus. Then naïve CD8+ T-cells can be primed by mature dendritic cells. In mature dendritic cells peptides presented by MHC class I molecules are derived from degradation of endogenous self-proteins or through the process of cross-presentation from degradation of exogenous proteins by the immunoproteasome. In the absence of infection, peripheral cells display peptides on MHC class I molecules derived from degradation of endogenous self-proteins by the constitutive proteasome. The pool of peptides derived from protein degradation by the constitutive proteasome differs from the pool peptides derived from protein degradation by the immunoproteasome. Thus the probability of an autoreactive naïve CD8+ T-cell that escaped negative selection, and converted by a mature dendritic cell to autoreactive cytolytic T-cell, to kill a normal cell in the periphery, is reduced.
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