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Alves Abrantes JJP, Veríssimo de Azevedo JC, Fernandes FL, Duarte Almeida V, Custódio De Oliveira LA, Ferreira de Oliveira MT, Galvão De Araújo JM, Lanza DCF, Bezerra FL, Andrade VS, Araújo de Medeiros Fernandes TA, Fernandes JV. Viruses as a potential environmental trigger of type 1 diabetes mellitus (Review). Biomed Rep 2024; 20:81. [PMID: 38628629 PMCID: PMC11019645 DOI: 10.3892/br.2024.1770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 09/07/2023] [Indexed: 04/19/2024] Open
Abstract
The etiopathogenesis of type 1 diabetes mellitus (T1DM) is a complex multifactorial process that involves an intricate network of genetic, epigenetic, immunological, and environmental factors. Despite the advances in recent years, some aspects of the mechanisms involved in triggering the disease are still unclear. Infections with certain viruses have been suggested as possible environmental triggers for the autoimmune process that leads to selective and progressive destruction of pancreatic β-cells and insufficiency of insulin production, which is its hallmark. In this review, advances in knowledge and evidence that suggest the participation of certain viruses in the mechanisms of disease initiation and progression are described. It has been accepted that environmental factors, including viruses, can initiate and possibly sustain, accelerate, or slow down the autoimmune process and consequently damage insulin-producing pancreatic β-cells. Although the role of these agents, especially human enteroviruses, has been exhaustively studied as the most likely triggers of the activation of autoimmunity that destroys pancreatic islets and leads to T1DM, certain doubts remain. Clinical epidemiological and experimental studies in humans and animals provide consistent and increasing evidence that persistent viral infections, especially with human enteroviruses and rotavirus infections, are associated with an increased risk of the disease in individuals genetically predisposed to autoimmunity.
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Affiliation(s)
| | | | - Fernando Liberalino Fernandes
- Department of Biomedical Sciences, Rio Grande do Norte State University, Mossoró, Rio Grande do Norte 59607-360, Brazil
| | - Valéria Duarte Almeida
- Department of Biomedical Sciences, Rio Grande do Norte State University, Mossoró, Rio Grande do Norte 59607-360, Brazil
| | | | | | - Josélio Maria Galvão De Araújo
- Department of Microbiology and Parasitology, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte 59078-970, Brazil
| | - Daniel Carlos Ferreira Lanza
- Laboratory of Applied Molecular Biology, Department of Biochemistry, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte 59078-970, Brazil
| | - Fabiana Lima Bezerra
- Department of Microbiology and Parasitology, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte 59078-970, Brazil
| | - Vania Sousa Andrade
- Department of Microbiology and Parasitology, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte 59078-970, Brazil
| | | | - José Veríssimo Fernandes
- Department of Microbiology and Parasitology, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte 59078-970, Brazil
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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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Brito-Sierra CA, Lannan MB, Malherbe LP, Siegel RW. The HLA class I immunopeptidomes of AAV capsid proteins. Front Immunol 2023; 14:1212136. [PMID: 37662941 PMCID: PMC10469481 DOI: 10.3389/fimmu.2023.1212136] [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: 04/25/2023] [Accepted: 07/26/2023] [Indexed: 09/05/2023] Open
Abstract
Introduction Cellular immune responses against AAV vector capsid represent an obstacle for successful gene therapy. Previous studies have used overlapping peptides spanning the entire capsid sequence to identify T cell epitopes recognized by AAV-specific CD8+ T cells. However, the repertoire of peptides naturally displayed by HLA class I molecules for CD8 T cell recognition is unknown. Methods Using mRNA transfected monocyte-derived dendritic cells (MDDCs) and MHC-associated peptide proteomics (MAPPs), we identified the HLA class I immunopeptidomes of AAV2, AAV6 and AAV9 capsids. MDDCs were isolated from a panel of healthy donors that have diverse alleles across the US population. mRNA-transfected MDDCs were lysed, the peptide:HLA complexes immunoprecipitated, and peptides eluted and analyzed by mass spectrometry. Results We identified 65 AAV capsid-derived peptides loaded on HLA class I molecules of mRNA transfected monocyte derived dendritic cells. The HLA class I peptides are distributed along the entire capsid and more than 60% are contained within HLA class II clusters. Most of the peptides are organized as single species, however we identified twelve clusters containing at least 2 peptides of different lengths. Only 9% of the identified peptides have been previously identified as T cell epitopes, demonstrating that the immunogenicity potential for the vast majority of the AAV HLA class I immunopeptidome remains uncharacterized. In contrast, 12 immunogenic epitopes identified before were not found to be naturally processed in our study. Remarkably, 11 naturally presented AAV peptides were highly conserved among the three serotypes analyzed suggesting the possibility of cross-reactive AAV-specific CD8 T cells. Discussion This work is the first comprehensive study identifying the naturally displayed HLA class I peptides derived from the capsid of AAVs. The results from this study can be used to generate strategies to assess immunogenicity risk and cross-reactivity among serotypes during gene therapies.
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Affiliation(s)
| | | | - Laurent P. Malherbe
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, United States
| | - Robert W. Siegel
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, United States
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van Olst L, Coenen L, Nieuwland JM, Rodriguez-Mogeda C, de Wit NM, Kamermans A, Middeldorp J, de Vries HE. Crossing borders in Alzheimer's disease: A T cell's perspective. Adv Drug Deliv Rev 2022; 188:114398. [PMID: 35780907 DOI: 10.1016/j.addr.2022.114398] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 05/31/2022] [Accepted: 06/03/2022] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is the most common form of dementia affecting millions of people worldwide. While different immunotherapies are imminent, currently only disease-modifying medications are available and a cure is lacking. Over the past decade, immunological interfaces of the central nervous system (CNS) and their role in neurodegenerative diseases received increasing attention. Specifically, emerging evidence shows that subsets of circulating CD8+ T cells cross the brain barriers and associate with AD pathology. To gain more insight into how the adaptive immune system is involved in disease pathogenesis, we here provide a comprehensive overview of the contribution of T cells to AD pathology, incorporating changes at the brain barriers. In addition, we review studies that provide translation of these findings by targeting T cells to combat AD pathology and cognitive decline. Importantly, these data show that immunological changes in AD are not confined to the CNS and that AD-associated systemic immune changes appear to affect brain homeostasis.
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Affiliation(s)
- L van Olst
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - L Coenen
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands; Department of Neurobiology and Aging, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - J M Nieuwland
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands; Department of Neurobiology and Aging, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - C Rodriguez-Mogeda
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - N M de Wit
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - A Kamermans
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - J Middeldorp
- Department of Neurobiology and Aging, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - H E de Vries
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands.
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5
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Zajec A, Trebušak Podkrajšek K, Tesovnik T, Šket R, Čugalj Kern B, Jenko Bizjan B, Šmigoc Schweiger D, Battelino T, Kovač J. Pathogenesis of Type 1 Diabetes: Established Facts and New Insights. Genes (Basel) 2022; 13:genes13040706. [PMID: 35456512 PMCID: PMC9032728 DOI: 10.3390/genes13040706] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/13/2022] [Accepted: 04/13/2022] [Indexed: 01/08/2023] Open
Abstract
Type 1 diabetes (T1D) is an autoimmune disease characterized by the T-cell-mediated destruction of insulin-producing β-cells in pancreatic islets. It generally occurs in genetically susceptible individuals, and genetics plays a major role in the development of islet autoimmunity. Furthermore, these processes are heterogeneous among individuals; hence, different endotypes have been proposed. In this review, we highlight the interplay between genetic predisposition and other non-genetic factors, such as viral infections, diet, and gut biome, which all potentially contribute to the aetiology of T1D. We also discuss a possible active role for β-cells in initiating the pathological processes. Another component in T1D predisposition is epigenetic influences, which represent a link between genetic susceptibility and environmental factors and may account for some of the disease heterogeneity. Accordingly, a shift towards personalized therapies may improve the treatment results and, therefore, result in better outcomes for individuals in the long-run. There is also a clear need for a better understanding of the preclinical phases of T1D and finding new predictive biomarkers for earlier diagnosis and therapy, with the final goal of reverting or even preventing the development of the disease.
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Affiliation(s)
- Ana Zajec
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
- Department of Paediatrics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Katarina Trebušak Podkrajšek
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
- Department of Paediatrics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Tine Tesovnik
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
| | - Robert Šket
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
| | - Barbara Čugalj Kern
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
- Department of Paediatrics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Barbara Jenko Bizjan
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
- Department of Paediatrics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Darja Šmigoc Schweiger
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
- Department of Paediatrics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Tadej Battelino
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
- Department of Paediatrics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Jernej Kovač
- Division of Paediatrics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (A.Z.); (K.T.P.); (T.T.); (R.Š.); (B.Č.K.); (B.J.B.); (D.Š.S.); (T.B.)
- Department of Paediatrics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
- Correspondence:
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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: 3] [Impact Index Per Article: 1.0] [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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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: 5] [Impact Index Per Article: 1.7] [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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8
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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: 6] [Impact Index Per Article: 2.0] [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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9
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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: 11] [Impact Index Per Article: 3.7] [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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