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Han XJ, Ma XL, Yang L, Wei YQ, Peng Y, Wei XW. Progress in Neoantigen Targeted Cancer Immunotherapies. Front Cell Dev Biol 2020; 8:728. [PMID: 32850843 PMCID: PMC7406675 DOI: 10.3389/fcell.2020.00728] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 07/14/2020] [Indexed: 02/05/2023] Open
Abstract
Immunotherapies that harness the immune system to kill cancer cells have showed significant therapeutic efficacy in many human malignancies. A growing number of studies have highlighted the relevance of neoantigens in recognizing cancer cells by intrinsic T cells. Cancer neoantigens are a direct consequence of somatic mutations presenting on the surface of individual cancer cells. Neoantigens are fully cancer-specific and exempt from central tolerance. In addition, neoantigens are important targets for checkpoint blockade therapy. Recently, technological innovations have made neoantigen discovery possible in a variety of malignancies, thus providing an impetus to develop novel immunotherapies that selectively enhance T cell reactivity for the destruction of cancer cells while leaving normal tissues unharmed. In this review, we aim to introduce the methods of the identification of neoantigens, the mutational patterns of human cancers, related clinical trials, neoantigen burden and sensitivity to immune checkpoint blockade. Moreover, we focus on relevant challenges of targeting neoantigens for cancer treatment.
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Mutis T, Xagara A, Spaapen RM. The Connection Between Minor H Antigens and Neoantigens and the Missing Link in Their Prediction. Front Immunol 2020; 11:1162. [PMID: 32670277 PMCID: PMC7326952 DOI: 10.3389/fimmu.2020.01162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 05/12/2020] [Indexed: 12/26/2022] Open
Abstract
For hundreds of thousands of years, the human genome has extensively evolved, resulting in genetic variations in almost every gene. Immunological reflections of these genetic variations become clearly visible after an allogeneic stem cell transplantation (allo-SCT) as minor Histocompatibility (H) antigens. Minor H antigens are peptides cleaved from genetically encoded variable protein regions after which they are presented at the cell surface by HLA molecules. After allo-SCT with minor H antigen mismatches between donor and recipient, donor T cells recognize the minor H antigens of the recipient as foreign, evoking strong alloreactive immune responses. Studies in the late eighties have discovered that a subset of minor H antigens are encoded by hematopoietic system-specific genes. After allo-SCT, this subset is strictly expressed on the hematopoietic malignant cells and was therefore the first well-defined highly immunogenic group of tumor-specific antigens. In the last decade, neoantigens derived from genetic mutations in tumors have been identified as another group of immunogenic tumor-specific antigens. Therefore, hematopoietic minor H antigens and neoantigens are therapeutic equivalents. This review will connect our current knowledge about the immune biology and identification of minor H antigens and neoantigens leading to novel conclusions on their prediction.
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Affiliation(s)
- Tuna Mutis
- Department of Hematology, Amsterdam UMC, VU Medical Center, Amsterdam, Netherlands
| | - Anastasia Xagara
- Department of Immunopathology, Sanquin Research, Amsterdam, Netherlands.,Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Robbert M Spaapen
- Department of Immunopathology, Sanquin Research, Amsterdam, Netherlands.,Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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Abstract
Malignant transformation of cells depends on accumulation of DNA damage. Over the past years we have learned that the T cell-based immune system frequently responds to the neoantigens that arise as a consequence of this DNA damage. Furthermore, recognition of neoantigens appears an important driver of the clinical activity of both T cell checkpoint blockade and adoptive T cell therapy as cancer immunotherapies. Here we review the evidence for the relevance of cancer neoantigens in tumor control and the biological properties of these antigens. We discuss recent technological advances utilized to identify neoantigens, and the T cells that recognize them, in individual patients. Finally, we discuss strategies that can be employed to exploit cancer neoantigens in clinical interventions.
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Affiliation(s)
- Ton N Schumacher
- Division of Molecular Oncology and Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands; , .,Oncode Institute, 3521AL Utrecht, The Netherlands
| | - Wouter Scheper
- Division of Molecular Oncology and Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands; , .,Oncode Institute, 3521AL Utrecht, The Netherlands
| | - Pia Kvistborg
- Division of Molecular Oncology and Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands; ,
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Goode EF, Smyth EC. Immunotherapy for Gastroesophageal Cancer. J Clin Med 2016; 5:jcm5100084. [PMID: 27669318 PMCID: PMC5086586 DOI: 10.3390/jcm5100084] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 09/07/2016] [Accepted: 09/14/2016] [Indexed: 12/29/2022] Open
Abstract
Survival for patients with advanced oesophageal and stomach cancer is poor; together these cancers are responsible for more than a million deaths per year globally. As chemotherapy and targeted therapies such as trastuzumab and ramucirumab result in modest improvements in survival but not long-term cure for such patients, development of alternative treatment approaches is warranted. Novel immunotherapy drugs such as checkpoint inhibitors have been paradigm changing in melanoma, non-small cell lung cancer and urothelial cancers. In this review, we assess the early evidence for efficacy of immunotherapy in patients with gastroesophageal cancer in addition to considering biomarkers associated with response to these treatments. Early results of Anti- Programmed Cell Death Protein-1 (anti-PD-1), anti-PD-L1 and anti-Cytotoxic T-lymphocyte assosciated protein-4 (anti-CTLA4) trials are examined, and we conclude with a discussion on the future direction for immunotherapy for gastroesophageal cancer patients.
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Affiliation(s)
- Emily F Goode
- The Royal Marsden Hospital, NHS Foundation Trust, London SW3 6JJ, UK.
| | - Elizabeth C Smyth
- The Royal Marsden Hospital, NHS Foundation Trust, London SW3 6JJ, UK.
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Abstract
INTRODUCTION Gastric and oesophageal cancers are a pressing global health problem with high mortality rates and poor outcomes for advanced disease. The mainstay of treatment in the palliative setting has traditionally been chemotherapy, which accrues only modest survival benefits. As with other cancer types, there is increasing interest in the use of immunotherapy approaches to improve outcomes. AREAS COVERED This paper reviews the aetiological and genetic characteristics of oesophagogastric (OG) cancers relevant to the application of immunotherapy and outlines the historical, present-day and potential future applications of immunotherapy in their management. EXPERT OPINION The use of agents targeting the PD1 pathway have led to impressive and durable responses in a minority of OG cancer patients and it would be expected that combinatorial approaches with chemotherapy, radiotherapy and other biological agents will improve responses further. Identification of clinically robust biomarkers is crucial in refining such approaches moving forwards. The application of modern sequencing technology to the development of personalized neoantigen-based vaccines represents an exciting amalgamation of genomics and immunotherapy, with potentially important clinical implications in OG cancer.
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Affiliation(s)
- Michael Davidson
- a The Royal Marsden Hospital NHS Foundation Trust , Gastro-Intestinal Cancer Research Department , London , United Kingdom
| | - Ian Chau
- a The Royal Marsden Hospital NHS Foundation Trust , Gastro-Intestinal Cancer Research Department , London , United Kingdom
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Martin SD, Coukos G, Holt RA, Nelson BH. Targeting the undruggable: immunotherapy meets personalized oncology in the genomic era. Ann Oncol 2015; 26:2367-74. [PMID: 26371284 PMCID: PMC4658541 DOI: 10.1093/annonc/mdv382] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 08/14/2015] [Accepted: 08/17/2015] [Indexed: 12/22/2022] Open
Abstract
Owing to recent advances in genomic technologies, personalized oncology is poised to fundamentally alter cancer therapy. In this paradigm, the mutational and transcriptional profiles of tumors are assessed, and personalized treatments are designed based on the specific molecular abnormalities relevant to each patient's cancer. To date, such approaches have yielded impressive clinical responses in some patients. However, a major limitation of this strategy has also been revealed: the vast majority of tumor mutations are not targetable by current pharmacological approaches. Immunotherapy offers a promising alternative to exploit tumor mutations as targets for clinical intervention. Mutated proteins can give rise to novel antigens (called neoantigens) that are recognized with high specificity by patient T cells. Indeed, neoantigen-specific T cells have been shown to underlie clinical responses to many standard treatments and immunotherapeutic interventions. Moreover, studies in mouse models targeting neoantigens, and early results from clinical trials, have established proof of concept for personalized immunotherapies targeting next-generation sequencing identified neoantigens. Here, we review basic immunological principles related to T-cell recognition of neoantigens, and we examine recent studies that use genomic data to design personalized immunotherapies. We discuss the opportunities and challenges that lie ahead on the road to improving patient outcomes by incorporating immunotherapy into the paradigm of personalized oncology.
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Affiliation(s)
- S D Martin
- Trev and Joyce Deeley Research Centre, British Columbia Cancer Agency, Victoria Interdisciplinary Oncology Program, University of British Columbia, Vancouver Michael Smith's Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, Canada
| | - G Coukos
- Ludwig Center for Cancer Research, University of Lausanne, Lausanne Hospital of the University of Lausanne (CHUV), Lausanne, Switzerland
| | - R A Holt
- Michael Smith's Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, Canada Molecular Biology and Biochemistry, Simon Fraser University, Vancouver Department of Medical Genetics, University of British Columbia, Vancouver
| | - B H Nelson
- Trev and Joyce Deeley Research Centre, British Columbia Cancer Agency, Victoria Department of Medical Genetics, University of British Columbia, Vancouver Department of Microbiology and Biochemistry, University of Victoria, Victoria, Canada
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7
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Improved structural method for T-cell cross-reactivity prediction. Mol Immunol 2015; 67:303-10. [PMID: 26141239 DOI: 10.1016/j.molimm.2015.06.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/03/2015] [Accepted: 06/16/2015] [Indexed: 10/23/2022]
Abstract
Cytotoxic T-lymphocytes (CTLs) are the key players of adaptive cellular immunity, being able to identify and eliminate infected cells through the interaction with peptide-loaded major histocompatibility complexes class I (pMHC-I). Despite the high specificity of this interaction, a given lymphocyte is actually able to recognize more than just one pMHC-I complex, a phenomenon referred as cross-reactivity. In the present work we describe the use of pMHC-I structural features as input for multivariate statistical methods, to perform standardized structure-based predictions of cross-reactivity among viral epitopes. Our improved approach was able to successfully identify cross-reactive targets among 28 naturally occurring hepatitis C virus (HCV) variants and among eight epitopes from the four dengue virus serotypes. In both cases, our results were supported by multiscale bootstrap resampling and by data from previously published in vitro experiments. The combined use of data from charges and accessible surface area (ASA) of selected residues over the pMHC-I surface provided a powerful way of assessing the structural features involved in triggering cross-reactive responses. Moreover, the use of an R package (pvclust) for assessing the uncertainty in the hierarchical cluster analysis provided a statistical support for the interpretation of results. Taken together, these methods can be applied to vaccine design, both for the selection of candidates capable of inducing immunity against different targets, or to identify epitopes that could trigger undesired immunological responses.
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van Buuren MM, Calis JJ, Schumacher TN. High sensitivity of cancer exome-based CD8 T cell neo-antigen identification. Oncoimmunology 2014; 3:e28836. [PMID: 25083320 PMCID: PMC4106163 DOI: 10.4161/onci.28836] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 04/09/2014] [Indexed: 02/04/2023] Open
Abstract
Recent data suggest that T-cell reactivity against tumor-specific neo-antigens may be central to the clinical efficacy of cancer immunotherapy. The development of personalized vaccines designed to boost T-cell reactivity against patient specific neo-antigens has been proposed largely on the basis of these findings. Work from several groups has demonstrated that novel tumor-specific antigens can be discovered through the use of cancer exome sequencing data, thereby providing a potential pipeline for the development of patient-specific vaccines. Importantly though, it has not been established which fraction of cancer neo-antigens that can be recognized by CD8+ T cells is successfully uncovered with the current exome-based epitope prediction strategies. Here, we use a data set comprising human cancer neo-antigens that was previously identified through the use of unbiased, computational-independent strategies to describe the potential of cancer exome-based neo-antigen discovery. This analysis shows a high sensitivity of exome-guided neo-antigen prediction of approximately 70%. We propose that future research should focus on the analysis and optimization of the specificity of neo-antigen prediction, and should undoubtedly entail the clinical evaluation of patient-specific vaccines with the aim of inducing immunoreactivity against tumor-displayed neo-antigens in a physiologically relevant context.
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Affiliation(s)
- Marit M van Buuren
- Department of Immunology; The Netherlands Cancer Institute; Amsterdam, The Netherlands
| | - Jorg Ja Calis
- Department of Immunology; The Netherlands Cancer Institute; Amsterdam, The Netherlands
| | - Ton Nm Schumacher
- Department of Immunology; The Netherlands Cancer Institute; Amsterdam, The Netherlands
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Calis JJA, Maybeno M, Greenbaum JA, Weiskopf D, De Silva AD, Sette A, Keşmir C, Peters B. Properties of MHC class I presented peptides that enhance immunogenicity. PLoS Comput Biol 2013; 9:e1003266. [PMID: 24204222 PMCID: PMC3808449 DOI: 10.1371/journal.pcbi.1003266] [Citation(s) in RCA: 551] [Impact Index Per Article: 50.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 08/23/2013] [Indexed: 12/14/2022] Open
Abstract
T-cells have to recognize peptides presented on MHC molecules to be activated and elicit their effector functions. Several studies demonstrate that some peptides are more immunogenic than others and therefore more likely to be T-cell epitopes. We set out to determine which properties cause such differences in immunogenicity. To this end, we collected and analyzed a large set of data describing the immunogenicity of peptides presented on various MHC-I molecules. Two main conclusions could be drawn from this analysis: First, in line with previous observations, we showed that positions P4–6 of a presented peptide are more important for immunogenicity. Second, some amino acids, especially those with large and aromatic side chains, are associated with immunogenicity. This information was combined into a simple model that was used to demonstrate that immunogenicity is, to a certain extent, predictable. This model (made available at http://tools.iedb.org/immunogenicity/) was validated with data from two independent epitope discovery studies. Interestingly, with this model we could show that T-cells are equipped to better recognize viral than human (self) peptides. After the past successful elucidation of different steps in the MHC-I presentation pathway, the identification of variables that influence immunogenicity will be an important next step in the investigation of T-cell epitopes and our understanding of cellular immune responses. T-cells have to recognize peptides presented on MHC molecules to be activated and elicit their effector functions. Some peptide-MHC-I complexes (pMHCs) are better recognized by T-cells; we call such pMHCs more immunogenic. For other pMHCs, no recognizing T-cells seem to exist; we call such pMHCs non-immunogenic. We set out to determine which properties of pMHCs cause such differences in immunogenicity, by carefully collecting a large set of immunogenic and non-immunogenic pMHCs, and analysing the difference between these sets. Two important observations were made: First, in line with previous observations, we showed that positions P4–6 of a presented peptide are more important for immunogenicity. Second, some amino acids, especially those with large and aromatic side chains, seem to be better recognized by T-cells as they associate with immunogenicity. Next, this information was combined into a simple model to predict the immunogenicity of new pMHCs (this model is made available at http://tools.iedb.org/immunogenicity/). Interestingly, with this model we could show that T-cells are equipped to strongly recognize viral peptides. After the past successful elucidation of different steps in the MHC-I presentation pathway, the identification of variables that influence immunogenicity will be an important next step in the investigation of T-cell epitopes and our understanding of cellular immune responses.
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Affiliation(s)
- Jorg J. A. Calis
- Theoretical Biology & Bioinformatics, Utrecht University, Utrecht, The Netherlands
- * E-mail:
| | - Matt Maybeno
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Jason A. Greenbaum
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Daniela Weiskopf
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Aruna D. De Silva
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
- Genetech Research Institute, Colombo, Sri Lanka
| | - Alessandro Sette
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Can Keşmir
- Theoretical Biology & Bioinformatics, Utrecht University, Utrecht, The Netherlands
| | - Bjoern Peters
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
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Ghosh A, Dogan Y, Moroz M, Holland AM, Yim NL, Rao UK, Young LF, Tannenbaum D, Masih D, Velardi E, Tsai JJ, Jenq RR, Penack O, Hanash AM, Smith OM, Piersanti K, Lezcano C, Murphy GF, Liu C, Palomba ML, Sauer MG, Sadelain M, Ponomarev V, van den Brink MRM. Adoptively transferred TRAIL+ T cells suppress GVHD and augment antitumor activity. J Clin Invest 2013; 123:2654-62. [PMID: 23676461 DOI: 10.1172/jci66301] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 03/14/2013] [Indexed: 01/24/2023] Open
Abstract
Current strategies to suppress graft-versus-host disease (GVHD) also compromise graft-versus-tumor (GVT) responses. Furthermore, most experimental strategies to separate GVHD and GVT responses merely spare GVT function without actually enhancing it. We have previously shown that endogenously expressed TNF-related apoptosis-inducing ligand (TRAIL) is required for optimal GVT activity against certain malignancies in recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT). In order to model a donor-derived cellular therapy, we genetically engineered T cells to overexpress TRAIL and adoptively transferred donor-type unsorted TRAIL+ T cells into mouse models of allo-HSCT. We found that murine TRAIL+ T cells induced apoptosis of alloreactive T cells, thereby reducing GVHD in a DR5-dependent manner. Furthermore, murine TRAIL+ T cells mediated enhanced in vitro and in vivo antilymphoma GVT response. Moreover, human TRAIL+ T cells mediated enhanced in vitro cytotoxicity against both human leukemia cell lines and against freshly isolated chronic lymphocytic leukemia (CLL) cells. Finally, as a model of off-the-shelf, donor-unrestricted antitumor cellular therapy, in vitro-generated TRAIL+ precursor T cells from third-party donors also mediated enhanced GVT response in the absence of GVHD. These data indicate that TRAIL-overexpressing donor T cells could potentially enhance the curative potential of allo-HSCT by increasing GVT response and suppressing GVHD.
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Affiliation(s)
- Arnab Ghosh
- Department of Immunology and Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.
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Abstract
Cancer cells deviate from normal body cells in two immunologically important ways. First, tumour cells carry tens to hundreds of protein-changing mutations that are either responsible for cellular transformation or that have accumulated as mere passengers. Second, as a consequence of genetic and epigenetic alterations, tumour cells express a series of proteins that are normally not present or present at lower levels. These changes lead to the presentation of an altered repertoire of MHC class I-associated peptides. Importantly, while there is now strong clinical evidence that cytotoxic T-cell activity against such tumour-associated antigens can lead to cancer regression, at present we fail to understand which tumour-associated antigens form the prime targets in effective immunotherapies. Here, we describe how recent developments in cancer genomics will make it feasible to establish the repertoire of tumour-associated epitopes on a patient-specific basis. The elucidation of this 'cancer antigenome' will be valuable to reveal how clinically successful immunotherapies mediate their effect. Furthermore, the description of the cancer antigenome should form the basis of novel forms of personalized cancer immunotherapy.
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Antunes DA, Rigo MM, Silva JP, Cibulski SP, Sinigaglia M, Chies JA, Vieira GF. Structural in silico analysis of cross-genotype-reactivity among naturally occurring HCV NS3-1073-variants in the context of HLA-A*02:01 allele. Mol Immunol 2011; 48:1461-7. [DOI: 10.1016/j.molimm.2011.03.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 02/15/2011] [Accepted: 03/28/2011] [Indexed: 12/17/2022]
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Turner MJ, Jellison ER, Lingenheld EG, Puddington L, Lefrançois L. Avidity maturation of memory CD8 T cells is limited by self-antigen expression. J Exp Med 2008; 205:1859-68. [PMID: 18625745 PMCID: PMC2525599 DOI: 10.1084/jem.20072390] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Accepted: 05/28/2008] [Indexed: 12/22/2022] Open
Abstract
Immune tolerance to self-antigens is a complex process that utilizes multiple mechanisms working in concert to maintain homeostasis and prevent autoimmunity. We developed a system that revealed a population of self-specific CD8 T cells within the endogenous T cell repertoire. Immunization of ovalbumin (OVA)-expressing transgenic mice with recombinant viruses expressing OVA-peptide variants induced self-reactive T cells in vivo that matured into memory T cells able to respond to secondary infection. However, whereas the avidity of memory cells in normal mice increased dramatically with repeated immunizations, avidity maturation was limited for self-specific CD8 T cells. Despite decreased avidity, such memory cells afforded protection against infection, but did not induce overt autoimmunity. Further, up-regulation of self-antigen expression in dendritic cells using an inducible system promoted programmed death-1 expression, but not clonal expansion of preexisting memory cells. Thus, the self-reactive T cell repertoire is controlled by overlapping mechanisms influenced by antigen dose.
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Affiliation(s)
- Michael J Turner
- Department of Immunology, University of Connecticut Health Center, Farmington, CT 06030, USA
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Grandics P. The cancer stem cell: evidence for its origin as an injured autoreactive T cell. Mol Cancer 2006; 5:6. [PMID: 16478542 PMCID: PMC1386699 DOI: 10.1186/1476-4598-5-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 02/14/2006] [Indexed: 02/06/2023] Open
Abstract
This review explores similarities between lymphocytes and cancer cells, and proposes a new model for the genesis of human cancer. We suggest that the development of cancer requires infection(s) during which antigenic determinants from pathogens mimicking self-antigens are co-presented to the immune system, leading to breaking T cell tolerance. Some level of autoimmunity is normal and necessary for effective pathogen eradication. However, autoreactive T cells must be eliminated by apoptosis when the immune response is terminated. Apoptosis can be deficient in the event of a weakened immune system, the causes of which are multifactorial. Some autoreactive T cells suffer genomic damage in this process, but manage to survive. The resulting cancer stem cell still retains some functions of an inflammatory T cell, so it seeks out sites of inflammation inside the body. Due to its defective constitutive production of inflammatory cytokines and other growth factors, a stroma is built at the site of inflammation similar to the temporary stroma built during wound healing. The cancer cells grow inside this stroma, forming a tumor that provides their vascular supply and protects them from cellular immune response. As cancer stem cells have plasticity comparable to normal stem cells, interactions with surrounding normal tissues cause them to give rise to all the various types of cancers, resembling differentiated tissue types. Metastases form at an advanced stage of the disease, with the proliferation of sites of inflammation inside the body following a similar mechanism. Immunosuppressive cancer therapies inadvertently re-invigorate pathogenic microorganisms and parasitic infections common to cancer, leading to a vicious circle of infection, autoimmunity and malignancy that ultimately dooms cancer patients. Based on this new understanding, we recommend a systemic approach to the development of cancer therapies that supports rather than antagonizes the immune system.
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