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Perron H. A tale of a hidden family of genetic immigrants. Microbes Infect 2024:105387. [PMID: 38944111 DOI: 10.1016/j.micinf.2024.105387] [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: 04/20/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/01/2024]
Abstract
Though not usual for the editors of a scientific journal to ask that a story be told to its readers, this special issue is offering an opportunity to pay tribute to all those who have made it possible for a long scientific journey to open up many research avenues, to access the discoveries of what was not known and to the understanding of what was unveiled in the field of human endogenous retroviruses. In particular, and beyond a simple fortuitous association, to show their pathogenic involvement in certain diseases whose causality has been the subject of numerous and variable hypotheses.
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Affiliation(s)
- Hervé Perron
- GeNeuro, 3 chemin du Pré-Fleuri, 1228 Plan-les-ouates, Geneva, Switzerland; Geneuro-Innovation, 60A, Avenue Rockefeller, 69008 Lyon, France.
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2
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da Silva AL, Guedes BLM, Santos SN, Correa GF, Nardy A, Nali LHDS, Bachi ALL, Romano CM. Beyond pathogens: the intriguing genetic legacy of endogenous retroviruses in host physiology. Front Cell Infect Microbiol 2024; 14:1379962. [PMID: 38655281 PMCID: PMC11035796 DOI: 10.3389/fcimb.2024.1379962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 03/22/2024] [Indexed: 04/26/2024] Open
Abstract
The notion that viruses played a crucial role in the evolution of life is not a new concept. However, more recent insights suggest that this perception might be even more expansive, highlighting the ongoing impact of viruses on host evolution. Endogenous retroviruses (ERVs) are considered genomic remnants of ancient viral infections acquired throughout vertebrate evolution. Their exogenous counterparts once infected the host's germline cells, eventually leading to the permanent endogenization of their respective proviruses. The success of ERV colonization is evident so that it constitutes 8% of the human genome. Emerging genomic studies indicate that endogenous retroviruses are not merely remnants of past infections but rather play a corollary role, despite not fully understood, in host genetic regulation. This review presents some evidence supporting the crucial role of endogenous retroviruses in regulating host genetics. We explore the involvement of human ERVs (HERVs) in key physiological processes, from their precise and orchestrated activities during cellular differentiation and pluripotency to their contributions to aging and cellular senescence. Additionally, we discuss the costs associated with hosting a substantial amount of preserved viral genetic material.
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Affiliation(s)
- Amanda Lopes da Silva
- Instituto de Medicina Tropical de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Bruno Luiz Miranda Guedes
- Instituto de Medicina Tropical de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Samuel Nascimento Santos
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | - Giovanna Francisco Correa
- Instituto de Medicina Tropical de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Ariane Nardy
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | | | - Andre Luis Lacerda Bachi
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | - Camila Malta Romano
- Instituto de Medicina Tropical de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
- Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil
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3
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Ruberto S, Cossu D, Sechi LA. Correlation between antibodies against the pathogenic pHERV-W envelope protein and the inflammatory phase of multiple sclerosis. Immunology 2024; 171:270-276. [PMID: 37985008 DOI: 10.1111/imm.13712] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 10/29/2023] [Indexed: 11/22/2023] Open
Abstract
The role of retroviral envelope proteins belonging to the Human Endogenous Retroviral family 'W' (HERV-W), specifically syncytin-1 and pathogenic HERV-W (pHERV-W), as potential risk factors in multiple sclerosis (MS) has been established. This study aimed to investigate the humoral response to syncytin-1 and pHERV-W-derived peptides in a group of relapsing remitting MS patients categorized as having acute or stable disease. Furthermore, an inhibition assay was conducted to assess the extent of cross-reactivity between the two epitopes. The findings revealed that MS patients in the acute phase exhibited a higher specific antibody response to the pHERV-W env epitope compared to syncytin-1. This suggests a potential pathogenic role for pHERV-W env during the inflammatory stages of central nervous system involvement, and these antibody responses could serve as useful biomarkers for monitoring the progression of the disease.
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Affiliation(s)
- Stefano Ruberto
- Division of Microbiology and Virology, Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Davide Cossu
- Division of Microbiology and Virology, Department of Biomedical Sciences, University of Sassari, Sassari, Italy
- Department of Neurology, Juntendo University, Tokyo, Japan
| | - Leonardo A Sechi
- Division of Microbiology and Virology, Department of Biomedical Sciences, University of Sassari, Sassari, Italy
- SC Microbiologia e Virologia, Azienda Ospedaliera Universitaria, Sassari, Italy
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Li Z, Wang Q, Lv N, Xu G, Yang X, Zhu B. Genome-wide identification of endogenous retrovirus elements and their active transcription in mink genome. MLIFE 2023; 2:201-208. [PMID: 38817617 PMCID: PMC10989824 DOI: 10.1002/mlf2.12074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 04/12/2023] [Accepted: 05/15/2023] [Indexed: 06/01/2024]
Abstract
Mammalian endogenous retroviruses (ERVs) are ancient retroviruses that have been integrated into genomes. ERVs were believed to be inactive until the discovery of ERV transcription in the mouse genome. However, the transcription level and function of ERV elements in mammalian genomes are not well understood. In this study, we performed the first genome-wide scanning of ERV loci in the American mink (Neogale vison) genome (NeoERV) followed by transcriptomic analysis to detect actively transcribed NeoERV elements. A total of 365,791 NeoERV loci were identified, and161,205 (44%) of these loci were found to be actively transcribed based on transcriptomic data from three types of tissues (amygdala, trachea and lung). More than one third of the actively transcribed NeoERV loci were tissue-specific. Furthermore, some of the active loci were associated with host gene transcription, and the level of NeoERV transcription was positively correlated with that of host genes, specifically when active loci were located in overlapped gene regions. An in-depth analysis of the envelope protein coding env gene showed that, in general, its transcription level was higher than that of NeoERVs, which is believed to be associated with host immunity.
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Affiliation(s)
- Zheng Li
- CAS Key Laboratory of Pathogen Microbiology and ImmunologyInstitute of Microbiology, Chinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Qing Wang
- CAS Key Laboratory of Pathogen Microbiology and ImmunologyInstitute of Microbiology, Chinese Academy of SciencesBeijingChina
- Jiangxi Science and Technology Normal UniversityNanchangChina
| | - Na Lv
- CAS Key Laboratory of Pathogen Microbiology and ImmunologyInstitute of Microbiology, Chinese Academy of SciencesBeijingChina
- Jinan Microecological Biomedicine Shandong LaboratoryJinanChina
| | - Guojin Xu
- CAS Key Laboratory of Pathogen Microbiology and ImmunologyInstitute of Microbiology, Chinese Academy of SciencesBeijingChina
| | - Xuemei Yang
- Beijing Pediatric Research InstituteBeijingChina
| | - Baoli Zhu
- CAS Key Laboratory of Pathogen Microbiology and ImmunologyInstitute of Microbiology, Chinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
- Jinan Microecological Biomedicine Shandong LaboratoryJinanChina
- Department of Pathogenic Biology, School of Basic Medical SciencesSouthwest Medical UniversityLuzhouChina
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Endogenous Retroviruses as Modulators of Innate Immunity. Pathogens 2023; 12:pathogens12020162. [PMID: 36839434 PMCID: PMC9963469 DOI: 10.3390/pathogens12020162] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/11/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Endogenous retroviruses (ERVs), or LTR retrotransposons, are a class of transposable elements that are highly represented in mammalian genomes. Human ERVs (HERVs) make up roughly 8.3% of the genome and over the course of evolution, HERV elements underwent positive selection and accrued mutations that rendered them non-infectious; thereby, the genome could co-opt them into constructive roles with important biological functions. In the past two decades, with the help of advances in sequencing technology, ERVs are increasingly considered to be important components of the innate immune response. While typically silenced, expression of HERVs can be induced in response to traumatic, toxic, or infection-related stress, leading to a buildup of viral transcripts and under certain circumstances, proteins, including functionally active reverse transcriptase and viral envelopes. The biological activity of HERVs in the context of the innate immune response can be based on the functional effect of four major viral components: (1) HERV LTRs, (2) HERV-derived RNAs, (3) HERV-derived RNA:DNA duplexes and cDNA, and (4) HERV-derived proteins and ribonucleoprotein complexes. In this review, we will discuss the implications of HERVs in all four contexts in relation to innate immunity and their association with various pathological disease states.
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Rangel SC, da Silva MD, da Silva AL, dos Santos JDMB, Neves LM, Pedrosa A, Rodrigues FM, Trettel CDS, Furtado GE, de Barros MP, Bachi ALL, Romano CM, Nali LHDS. Human endogenous retroviruses and the inflammatory response: A vicious circle associated with health and illness. Front Immunol 2022; 13:1057791. [PMID: 36518758 PMCID: PMC9744114 DOI: 10.3389/fimmu.2022.1057791] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 10/31/2022] [Indexed: 11/24/2022] Open
Abstract
Human Endogenous Retroviruses (HERVs) are derived from ancient exogenous retroviral infections that have infected our ancestors' germline cells, underwent endogenization process, and were passed throughout the generations by retrotransposition and hereditary transmission. HERVs comprise 8% of the human genome and are critical for several physiological activities. Yet, HERVs reactivation is involved in pathological process as cancer and autoimmune diseases. In this review, we summarize the multiple aspects of HERVs' role within the human genome, as well as virological and molecular aspects, and their fusogenic property. We also discuss possibilities of how the HERVs are possibly transactivated and participate in modulating the inflammatory response in health conditions. An update on their role in several autoimmune, inflammatory, and aging-related diseases is also presented.
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Affiliation(s)
- Sara Coelho Rangel
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | | | - Amanda Lopes da Silva
- Laboratório de Virologia, Instituto de Medicina Tropical de São Paulo, Universidade de São Paulo, São Paulo, Brazil
| | | | - Lucas Melo Neves
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | - Ana Pedrosa
- CNC-Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, (3004-504), Coimbra, Portugal
| | | | - Caio dos Santos Trettel
- Interdisciplinary Program in Health Sciences, Institute of Physical Activity Sciences and Sports (ICAFE), Cruzeiro do Sul University, São Paulo, Brazil
| | - Guilherme Eustáquio Furtado
- Polytechnic Institute of Coimbra, Applied Research Institute, Rua da Misericórdia, Lagar dos Cortiços – S. Martinho do Bispo, Coimbra, Portugal
| | - Marcelo Paes de Barros
- Interdisciplinary Program in Health Sciences, Institute of Physical Activity Sciences and Sports (ICAFE), Cruzeiro do Sul University, São Paulo, Brazil
| | - André Luis Lacerda Bachi
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | - Camila Malta Romano
- Laboratório de Virologia, Instituto de Medicina Tropical de São Paulo, Universidade de São Paulo, São Paulo, Brazil
- Hospital das Clínicas HCFMUSP (LIM52), Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
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Ilse V, Scholz R, Wermann M, Naumann M, Staege MS, Roßner S, Cynis H. Immunogenicity of the Envelope Surface Unit of Human Endogenous Retrovirus K18 in Mice. Int J Mol Sci 2022; 23:ijms23158330. [PMID: 35955468 PMCID: PMC9369184 DOI: 10.3390/ijms23158330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/21/2022] [Accepted: 07/25/2022] [Indexed: 02/06/2023] Open
Abstract
The triggers for the development of multiple sclerosis (MS) have not been fully understood to date. One hypothesis proposes a viral etiology. Interestingly, viral proteins from human endogenous retroviruses (HERVs) may play a role in the pathogenesis of MS. Allelic variants of the HERV-K18 env gene represent a genetic risk factor for MS, and the envelope protein is considered to be an Epstein–Barr virus-trans-activated superantigen. To further specify a possible role for HERV-K18 in MS, the present study examined the immunogenicity of the purified surface unit (SU). HERV-K18(SU) induced envelope-specific plasma IgG in immunized mice and triggered proliferation of T cells isolated from these mice. It did not trigger phenotypic changes in a mouse model of experimental autoimmune encephalomyelitis. Further studies are needed to investigate the underlying mechanisms of HERV-K18 interaction with immune system regulators in more detail.
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Affiliation(s)
- Victoria Ilse
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, Weinbergweg 22, 06120 Halle, Germany; (V.I.); (R.S.); (M.W.); (M.N.)
| | - Rebekka Scholz
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, Weinbergweg 22, 06120 Halle, Germany; (V.I.); (R.S.); (M.W.); (M.N.)
| | - Michael Wermann
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, Weinbergweg 22, 06120 Halle, Germany; (V.I.); (R.S.); (M.W.); (M.N.)
| | - Marcel Naumann
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, Weinbergweg 22, 06120 Halle, Germany; (V.I.); (R.S.); (M.W.); (M.N.)
| | - Martin S. Staege
- Department of Surgical and Conservative Pediatrics and Adolescent Medicine, Medical Faculty, Martin Luther University Halle-Wittenberg, Ernst-Grube-Str. 40, 06097 Halle, Germany;
| | - Steffen Roßner
- Paul Flechsig Institute for Brain Research, Leipzig University, Liebigstraße 19, 04103 Leipzig, Germany;
| | - Holger Cynis
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, Weinbergweg 22, 06120 Halle, Germany; (V.I.); (R.S.); (M.W.); (M.N.)
- Correspondence: ; Tel.: +49-345-13142835; Fax: +49-345-13142801
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8
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BERGALLO M, LOIACONO E, GALLIANO I, MONTANARI P, PERUZZI L, TOVO PA, COPPO R. HERV-K and W expression in peripheral mononuclear cells of children with Henoch-Schönlein purpura and relation with TLR activation. Minerva Pediatr (Torino) 2022; 74:421-427. [DOI: 10.23736/s2724-5276.17.04717-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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DeRosa H, Richter T, Wilkinson C, Hunter RG. Bridging the Gap Between Environmental Adversity and Neuropsychiatric Disorders: The Role of Transposable Elements. Front Genet 2022; 13:813510. [PMID: 35711940 PMCID: PMC9196244 DOI: 10.3389/fgene.2022.813510] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 04/13/2022] [Indexed: 12/21/2022] Open
Abstract
Long regarded as “junk DNA,” transposable elements (TEs) have recently garnered much attention for their role in promoting genetic diversity and plasticity. While many processes involved in mammalian development require TE activity, deleterious TE insertions are a hallmark of several psychiatric disorders. Moreover, stressful events including exposure to gestational infection and trauma, are major risk factors for developing psychiatric illnesses. Here, we will provide evidence demonstrating the intersection of stressful events, atypical TE expression, and their epigenetic regulation, which may explain how neuropsychiatric phenotypes manifest. In this way, TEs may be the “bridge” between environmental perturbations and psychopathology.
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Affiliation(s)
- Holly DeRosa
- Psychology Department, Developmental Brain Sciences Program, College of Liberal Arts, University of Massachusetts Boston, Boston, MA, United States
| | - Troy Richter
- Psychology Department, Developmental Brain Sciences Program, College of Liberal Arts, University of Massachusetts Boston, Boston, MA, United States
| | - Cooper Wilkinson
- Psychology Department, Developmental Brain Sciences Program, College of Liberal Arts, University of Massachusetts Boston, Boston, MA, United States
| | - Richard G Hunter
- Psychology Department, Developmental Brain Sciences Program, College of Liberal Arts, University of Massachusetts Boston, Boston, MA, United States
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Bello-Morales R, Andreu S, Ripa I, López-Guerrero JA. HSV-1 and Endogenous Retroviruses as Risk Factors in Demyelination. Int J Mol Sci 2021; 22:ijms22115738. [PMID: 34072259 PMCID: PMC8199333 DOI: 10.3390/ijms22115738] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 12/19/2022] Open
Abstract
Herpes simplex virus type 1 (HSV-1) is a neurotropic alphaherpesvirus that can infect the peripheral and central nervous systems, and it has been implicated in demyelinating and neurodegenerative processes. Transposable elements (TEs) are DNA sequences that can move from one genomic location to another. TEs have been linked to several diseases affecting the central nervous system (CNS), including multiple sclerosis (MS), a demyelinating disease of unknown etiology influenced by genetic and environmental factors. Exogenous viral transactivators may activate certain retrotransposons or class I TEs. In this context, several herpesviruses have been linked to MS, and one of them, HSV-1, might act as a risk factor by mediating processes such as molecular mimicry, remyelination, and activity of endogenous retroviruses (ERVs). Several herpesviruses have been involved in the regulation of human ERVs (HERVs), and HSV-1 in particular can modulate HERVs in cells involved in MS pathogenesis. This review exposes current knowledge about the relationship between HSV-1 and human ERVs, focusing on their contribution as a risk factor for MS.
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Affiliation(s)
- Raquel Bello-Morales
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; (S.A.); (I.R.); (J.A.L.-G.)
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, 28049 Madrid, Spain
- Correspondence:
| | - Sabina Andreu
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; (S.A.); (I.R.); (J.A.L.-G.)
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, 28049 Madrid, Spain
| | - Inés Ripa
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; (S.A.); (I.R.); (J.A.L.-G.)
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, 28049 Madrid, Spain
| | - José Antonio López-Guerrero
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; (S.A.); (I.R.); (J.A.L.-G.)
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, 28049 Madrid, Spain
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Römer C. Viruses and Endogenous Retroviruses as Roots for Neuroinflammation and Neurodegenerative Diseases. Front Neurosci 2021; 15:648629. [PMID: 33776642 PMCID: PMC7994506 DOI: 10.3389/fnins.2021.648629] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 02/05/2021] [Indexed: 12/15/2022] Open
Abstract
Many neurodegenerative diseases are associated with chronic inflammation in the brain and periphery giving rise to a continuous imbalance of immune processes. Next to inflammation markers, activation of transposable elements, including long intrespersed nuclear elements (LINE) elements and endogenous retroviruses (ERVs), has been identified during neurodegenerative disease progression and even correlated with the clinical severity of the disease. ERVs are remnants of viral infections in the human genome acquired during evolution. Upon activation, they produce transcripts and the phylogenetically youngest ones are still able to produce viral-like particles. In addition, ERVs can bind transcription factors and modulate immune response. Being between own and foreign, ERVs are reviewed in the context of viral infections of the central nervous system, in aging and neurodegenerative diseases. Moreover, this review tests the hypothesis that viral infection may be a trigger at the onset of neuroinflammation and that ERVs sustain the inflammatory imbalance by summarizing existing data of neurodegenerative diseases associated with viruses and/or ERVs.
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Affiliation(s)
- Christine Römer
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, The Berlin Institute for Medical Systems Biology, Berlin, Germany
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12
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Gröger V, Emmer A, Staege MS, Cynis H. Endogenous Retroviruses in Nervous System Disorders. Pharmaceuticals (Basel) 2021; 14:ph14010070. [PMID: 33467098 PMCID: PMC7829834 DOI: 10.3390/ph14010070] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/11/2021] [Accepted: 01/13/2021] [Indexed: 02/06/2023] Open
Abstract
Human endogenous retroviruses (HERV) have been implicated in the pathogenesis of several nervous system disorders including multiple sclerosis and amyotrophic lateral sclerosis. The toxicity of HERV-derived RNAs and proteins for neuronal cells has been demonstrated. The involvement of HERV in the pathogenesis of currently incurable diseases might offer new treatment strategies based on the inhibition of HERV activities by small molecules or therapeutic antibodies.
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Affiliation(s)
- Victoria Gröger
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, 06120 Halle (Saale), Germany;
| | - Alexander Emmer
- Department of Neurology, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany;
| | - Martin S. Staege
- Department of Surgical and Conservative Pediatrics and Adolescent Medicine, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
- Correspondence: (M.S.S.); (H.C.); Tel.: +49-345-557-7280 (M.S.S.); +49-345-13142835 (H.C.)
| | - Holger Cynis
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, 06120 Halle (Saale), Germany;
- Correspondence: (M.S.S.); (H.C.); Tel.: +49-345-557-7280 (M.S.S.); +49-345-13142835 (H.C.)
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13
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Human endogenous retrovirus W family envelope protein (HERV-W env) facilitates the production of TNF-α and IL-10 by inhibiting MyD88s in glial cells. Arch Virol 2021; 166:1035-1045. [PMID: 33438105 DOI: 10.1007/s00705-020-04933-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 11/07/2020] [Indexed: 02/07/2023]
Abstract
Human endogenous retrovirus W family envelope protein (HERV-W env) is associated with several neurological and psychiatric disorders, including multiple sclerosis (MS) and schizophrenia. Clinical studies have demonstrated a common link between inflammatory abnormalities and HERV-W env in neuropsychiatric diseases. Nonetheless, the molecular mechanisms by which HERV-W env mediates neuroinflammation are still unclear. In this study, we found that HERV-W env significantly increased the mRNA and protein levels of TNF-α and IL-10 in U251 and A172 cells. HERV-W env also induced a notable increase in Toll-like receptor 4 (TLR4). Knockdown of TLR4 impaired the expressions of TNF-α and IL-10 induced by HERV-W env. Overexpression of HERV-W env led to the upregulation of MyD88 but caused a decrease in MyD88s. MyD88s overexpression suppressed the expressions of TNF-α and IL-10 induced by HERV-W env. These findings indicate that HERV-W env upregulates the expressions of IL-10 and TNF-α by inhibiting the production of MyD88s in glial cells. This work sheds light on the immune pathogenesis of HERV-W env in neuropsychiatric disorders.
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Lin KY, Wang WD, Lin CH, Rastegari E, Su YH, Chang YT, Liao YF, Chang YC, Pi H, Yu BY, Chen SH, Lin CY, Lu MY, Su TY, Tzou FY, Chan CC, Hsu HJ. Piwi reduction in the aged niche eliminates germline stem cells via Toll-GSK3 signaling. Nat Commun 2020; 11:3147. [PMID: 32561720 PMCID: PMC7305233 DOI: 10.1038/s41467-020-16858-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 05/30/2020] [Indexed: 12/13/2022] Open
Abstract
Transposons are known to participate in tissue aging, but their effects on aged stem cells remain unclear. Here, we report that in the Drosophila ovarian germline stem cell (GSC) niche, aging-related reductions in expression of Piwi (a transposon silencer) derepress retrotransposons and cause GSC loss. Suppression of Piwi expression in the young niche mimics the aged niche, causing retrotransposon depression and coincident activation of Toll-mediated signaling, which promotes Glycogen synthase kinase 3 activity to degrade β-catenin. Disruption of β-catenin-E-cadherin-mediated GSC anchorage then results in GSC loss. Knocking down gypsy (a highly active retrotransposon) or toll, or inhibiting reverse transcription in the piwi-deficient niche, suppresses GSK3 activity and β-catenin degradation, restoring GSC-niche attachment. This retrotransposon-mediated impairment of aged stem cell maintenance may have relevance in many tissues, and could represent a viable therapeutic target for aging-related tissue degeneration.
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Affiliation(s)
- Kun-Yang Lin
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, 11529, Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Wen-Der Wang
- Department of BioAgricultural Sciences, National Chiayi University, Chiayi City, 60004, Taiwan
| | - Chi-Hung Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Elham Rastegari
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Yu-Han Su
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Yu-Tzu Chang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Yung-Feng Liao
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Yi-Chieh Chang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Kweishan, Taoyuan, Taiwan
| | - Haiwei Pi
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Kweishan, Taoyuan, Taiwan
| | - Bo-Yi Yu
- Institute of Information Science, Academia Sinica, Taipei, 11529, Taiwan
| | - Shu-Hwa Chen
- Institute of Information Science, Academia Sinica, Taipei, 11529, Taiwan
| | - Chung-Yen Lin
- Institute of Information Science, Academia Sinica, Taipei, 11529, Taiwan
| | - Mei-Yeh Lu
- Biodiversity Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Tsu-Yi Su
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, 10617, Taiwan
| | - Fei-Yang Tzou
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, 10617, Taiwan
| | - Chih-Chiang Chan
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, 10617, Taiwan
| | - Hwei-Jan Hsu
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, 11529, Taiwan.
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan.
- Biotechnology Center, National Chung Hsing University, Taichung, 40227, Taiwan.
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15
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Gruchot J, Kremer D, Küry P. Neural Cell Responses Upon Exposure to Human Endogenous Retroviruses. Front Genet 2019; 10:655. [PMID: 31354794 PMCID: PMC6637040 DOI: 10.3389/fgene.2019.00655] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/20/2019] [Indexed: 12/21/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are ancient retroviral elements, which invaded the human germ line several million years ago. Subsequent retrotransposition events amplified these sequences, resulting in approximately 8% of the human genome being composed of HERV sequences today. These genetic elements, normally dormant within human genomes, can be (re)-activated by environmental factors such as infections with other viruses, leading to the expression of viral proteins and, in some instances, even to viral particle production. Several studies have shown that the expression of these retroviral elements correlates with the onset and progression of neurological diseases such as multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Further studies provided evidence on additional roles for HERVs in schizophrenia (SCZ). Since these diseases are still not well understood, HERVs might constitute a new category of pathogenic components that could significantly change our understanding of these pathologies. Moreover, knowledge about their mode of action might also help to develop novel and more powerful approaches for the treatment of these complex diseases. Therefore, the main scope of this review is a description of the current knowledge on the involvement of HERV-W and HERV-K in neurological disease specifically focusing on the effects they exert on neural cells of the central nervous system.
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Affiliation(s)
- Joel Gruchot
- Department of Neurology, Neuroregeneration, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - David Kremer
- Department of Neurology, Neuroregeneration, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Patrick Küry
- Department of Neurology, Neuroregeneration, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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16
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Diebold M, Derfuss T. The monoclonal antibody GNbAC1: targeting human endogenous retroviruses in multiple sclerosis. Ther Adv Neurol Disord 2019; 12:1756286419833574. [PMID: 30873219 PMCID: PMC6407165 DOI: 10.1177/1756286419833574] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 01/10/2019] [Indexed: 12/12/2022] Open
Abstract
Background: Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS). Despite improvements of immunomodulatory therapies in relapsing–remitting MS, the pathomechanisms of progressive disease are poorly understood and therapeutically addressed to date. A pathophysiological role for proteins encoded by human endogenous retroviruses (HERVs) has been proposed. GNbAC1 is a monoclonal antibody directed against the envelope protein of a HERV with postulated involvement in MS. Methods: This review addresses the treatment concept of GNbAC1, the design, preclinical and clinical development of the antibody, as published by November 2018. All four in-human trials (of which two addressed MS) are discussed. Conclusion: The treatment concept of GNbAC1 is appealing but remains controversial due to conflicting results regarding the hypothesized underlying pathomechanism. Anticipated immunomodulatory effects were not observed in clinical or pharmacodynamic analyses of the currently available data. However, a magnetic resonance imaging sign compatible with the remyelinating potential of GNbAC1 encouraged further development of this antibody in progressive MS. No relevant issues with tolerability or safety have been described to date.
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Affiliation(s)
- Martin Diebold
- Neurological Policlinic and Clinic, University Hospital and University of Basel, Basel, Switzerland
| | - Tobias Derfuss
- Neurological Policlinic and Clinic, University Hospital and University of Basel, Petersgraben 4, Basel, 4031, Switzerland
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17
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Marrodan M, Alessandro L, Farez MF, Correale J. The role of infections in multiple sclerosis. Mult Scler 2019; 25:891-901. [DOI: 10.1177/1352458518823940] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Several lines of evidence suggest that multiple sclerosis (MS), like other autoimmune diseases, may be triggered by microbial infections. Pathogens associated with development or exacerbation of MS include bacteria, such as Chlamydia pneumoniae, Staphylococcus aureus-produced enterotoxins that function as superantigens, and viruses of the Herpesviridae (Epstein–Barr virus and human herpes virus 6) and human endogenous retrovirus families. However, to date, no single pathogen has been accepted as causal agent. In addition, common upper respiratory, gastrointestinal, and urogenital tract infections have also been associated with MS exacerbations. Although evidence of an infectious etiology as cause of MS in humans remains inconclusive, microbial agents may modulate the neuroimmunological system of genetically susceptible individuals. Decoding the epidemiological contribution of different microorganisms to MS, along with their pathogenic mechanisms, may help develop new treatment strategies and prevent relapses.
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Affiliation(s)
| | | | - Mauricio F Farez
- Center for Research on Neuroimmunological Diseases, FLENI, Buenos Aires, Argentina
| | - Jorge Correale
- Department of Neurology, FLENI, Buenos Aires, Argentina; Center for Research on Neuroimmunological Diseases, FLENI, Buenos Aires, Argentina
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18
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Molano-González N, Rojas M, Monsalve DM, Pacheco Y, Acosta-Ampudia Y, Rodríguez Y, Rodríguez-Jimenez M, Ramírez-Santana C, Anaya JM. Cluster analysis of autoimmune rheumatic diseases based on autoantibodies. New insights for polyautoimmunity. J Autoimmun 2018; 98:24-32. [PMID: 30459097 DOI: 10.1016/j.jaut.2018.11.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 11/08/2018] [Accepted: 11/12/2018] [Indexed: 12/19/2022]
Abstract
Autoimmune diseases (ADs) are a chronic and clinically heterogeneous group of diseases characterized by share common immunopathogenic mechanisms and risk factors (i.e., the autoimmune tautology), which explain the fact that one AD may coexist with others (i.e., polyautoimmunity - PolyA). In the present exploratory study, a mixed-cluster analysis of the most common autoimmune rheumatic diseases (ARDs) was done. A total of 187 consecutive women with established systemic lupus erythematosus (n = 70), rheumatoid arthritis (n = 51), systemic sclerosis (n = 35) and Sjögren's syndrome (n = 31) were included. A comprehensive clinical, autoantibody and cytokine assessment was simultaneously done. Total PolyA was registered in 142 (75.9%) patients. Six clusters were obtained, built mainly on autoantibodies: PolyA-I to -VI. The PolyA-III cluster showed the highest frequency of overt PolyA (p = 0.01), and the PolyA-I, -III, and -IV clusters exhibited the highest positivity for IL-12/23p40 (p = 0.015). These results provide new insights into the pathophysiology of PolyA and warrant prospective validation to enable development of a more accurate taxonomy of ARDs.
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Affiliation(s)
- Nicolás Molano-González
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia
| | - Manuel Rojas
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia; Doctoral Program in Biomedical Sciences, Universidad del Rosario, Bogota, Colombia
| | - Diana M Monsalve
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia
| | - Yovana Pacheco
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia
| | - Yeny Acosta-Ampudia
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia
| | - Yhojan Rodríguez
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia
| | - Monica Rodríguez-Jimenez
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia
| | - Carolina Ramírez-Santana
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia
| | - Juan-Manuel Anaya
- Center for Autoimmune Diseases Research (CREA), School of Medicine and Health Sciences, Universidad del Rosario, Bogota, Colombia.
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19
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Grandi N, Tramontano E. Human Endogenous Retroviruses Are Ancient Acquired Elements Still Shaping Innate Immune Responses. Front Immunol 2018; 9:2039. [PMID: 30250470 PMCID: PMC6139349 DOI: 10.3389/fimmu.2018.02039] [Citation(s) in RCA: 180] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 08/20/2018] [Indexed: 12/25/2022] Open
Abstract
About 8% of our genome is composed of sequences with viral origin, namely human Endogenous Retroviruses (HERVs). HERVs are relics of ancient infections that affected the primates' germ line along the last 100 million of years, and became stable elements at the interface between self and foreign DNA. Intriguingly, HERV co-evolution with the host led to the domestication of activities previously devoted to the retrovirus life cycle, providing novel cellular functions. For example, selected HERV envelope proteins have been coopted for pregnancy-related purposes, and proviral Long Terminal Repeats participate in the transcriptional regulation of various cellular genes. Given the HERV persistence in the host genome and its basal expression in most healthy tissues, it is reasonable that human defenses should prevent HERV-mediated immune activation. Despite this, HERVs and their products (including RNA, cytosolic DNA, and proteins) are still able to modulate and be influenced by the host immune system, fascinatingly suggesting a central role in the evolution and functioning of the human innate immunity. Indeed, HERV sequences had been major contributors in shaping and expanding the interferon network, dispersing inducible genes that have been occasionally domesticated in various mammalian lineages. Also the HERV integration within or near to genes encoding for critical immune factors has been shown to influence their activity, or to be responsible for their polymorphic variation in the human population, such as in the case of an HERV-K(HML10) provirus in the major histocompatibility complex region. In addition, HERV expressed products have been shown to modulate innate immunity effectors, being therefore often related on the one side to inflammatory and autoimmune disorders, while on the other side to the control of excessive immune activation through their immunosuppressive properties. Finally, HERVs have been proposed to establish a protective effect against exogenous infections. The present review summarizes the involvement of HERVs and their products in innate immune responses, describing how their intricate interplay with the first line of human defenses can actively contribute either to the host protection or to his damage, implying a subtle balance between the persistence of HERV expression and the maintenance of a basal immune alert.
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Affiliation(s)
- Nicole Grandi
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Enzo Tramontano
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy.,Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Cagliari, Italy
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20
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Curtin F, Bernard C, Levet S, Perron H, Porchet H, Médina J, Malpass S, Lloyd D, Simpson R. A new therapeutic approach for type 1 diabetes: Rationale for GNbAC1, an anti-HERV-W-Env monoclonal antibody. Diabetes Obes Metab 2018; 20:2075-2084. [PMID: 29749030 DOI: 10.1111/dom.13357] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/08/2018] [Accepted: 05/09/2018] [Indexed: 12/22/2022]
Abstract
We describe a newly identified therapeutic target for type 1 diabetes (T1D): an envelope protein of endogenous retroviral origin, human endogenous retrovirus W envelope (HERV-W-Env). HERV-W-Env was found to be detected in the blood of ~60% of patients with T1D and is expressed in acinar pancreatic cells of 75% of patients with T1D at post mortem examination. Preclinical experiments showed that this protein displays direct cytotoxicity on human β-islet cells. In vivo HERV-W-Env impairs the insulin and glucose metabolism in transgenic mice expressing HERV-W-Env. GNbAC1, an IgG4 monoclonal antibody, has been developed to specifically target HERV-W-Env and to neutralize the effect of HERV-W-Env in vitro and in vivo. GNbAC1 is currently in clinical development for multiple sclerosis and > 300 subjects have been administered with GNbAC1 so far. GNbAC1 is now being tested in T1D in the RAINBOW-T1D study, which is a randomized placebo-controlled study with the objective of showing the safety and pharmacodynamic response of GNbAC1 in patients who have had T1D with a maximum of 4 years' duration. GNbAC1 is being tested vs placebo at the dose of 6 mg/kg in 60 patients during six repeated administrations for 6 months; a 6-month open-label extension will follow. The primary endpoint is to assess safety, and secondary endpoints are the pharmacodynamic responses to GNbAC1. GNbAC1 targeting HERV-W-Env is currently in clinical development in T1D, with the first safety and pharmacodynamic study. If the study results are positive, this may open the door to the development of an innovative non-immunomodulatory disease-modifying treatment for T1D.
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Affiliation(s)
- Francois Curtin
- GeNeuro SA, Plan-les-Ouates, Switzerland
- Division of Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | | | | | - Hervé Perron
- GeNeuro SA, Plan-les-Ouates, Switzerland
- Geneuro-Innovation, Lyon, France
- Laboratory of Immune Deficiencies, Faculty of Medicine Laënnec, University of Lyon, Lyon, France
| | - Hervé Porchet
- GeNeuro SA, Plan-les-Ouates, Switzerland
- Department of Pharmacology, University of Pretoria, Pretoria, South Africa
| | | | - Sam Malpass
- Southern Star Research Pty Ltd, Gordon, Australia
| | - David Lloyd
- Southern Star Research Pty Ltd, Gordon, Australia
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21
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Morris G, Maes M, Murdjeva M, Puri BK. Do Human Endogenous Retroviruses Contribute to Multiple Sclerosis, and if So, How? Mol Neurobiol 2018; 56:2590-2605. [PMID: 30047100 PMCID: PMC6459794 DOI: 10.1007/s12035-018-1255-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/17/2018] [Indexed: 12/24/2022]
Abstract
The gammaretroviral human endogenous retrovirus (HERV) families MRSV/HERV-W and HERV-H (including the closely related HERV-Fc1) are associated with an increased risk of multiple sclerosis (MS). Complete HERV sequences betray their endogenous retroviral origin, with open reading frames in gag, pro, pol and env being flanked by two long terminal repeats containing promoter and enhancer sequences with the capacity to regulate HERV transactivation and the activity of host genes in spite of endogenous epigenetic repression mechanisms. HERV virions, RNA, cDNA, Gag and Env, and antibodies to HERV transcriptional products, have variously been found in the blood and/or brain and/or cerebrospinal fluid of MS patients, with the HERV expression level being associated with disease status. Furthermore, some HERV-associated single nucleotide polymorphisms (SNPs), such as rs662139 T/C in a 3-kb region of Xq22.3 containing a HERV-W env locus, and rs391745, upstream of the HERV-Fc1 locus on the X chromosome, are associated with MS susceptibility, while a negative association has been reported with SNPs in the tripartite motif-containing (TRIM) protein-encoding genes TRIM5 and TRIM22. Factors affecting HERV transcription include immune activation and inflammation, since HERV promoter regions possess binding sites for related transcription factors; oxidative stress, with oxidation of guanine to 8-oxoguanine and conversion of cytosine to 5-hydroxymethylcytosine preventing binding of methyl groups transferred by DNA methyltransferases; oxidative stress also inhibits the activity of deacetylases, thereby favouring the acetylation of histone lysine residues favouring gene expression; interferon beta; natalizumab treatment; impaired epigenetic regulation; and the sex of patients.
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Affiliation(s)
- Gerwyn Morris
- IMPACT Strategic Research Centre, School of Medicine, Barwon Health, Deakin University, Geelong, Victoria, Australia
| | - Michael Maes
- IMPACT Strategic Research Centre, School of Medicine, Barwon Health, Deakin University, Geelong, Victoria, Australia
- Department of Psychiatry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Marianna Murdjeva
- Department of Microbiology and Immunology, Medical University, Plovdiv, Bulgaria
| | - Basant K Puri
- Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK.
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22
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Kremer D, Küry P, Hartung HP. ECTRIMS/ACTRIMS 2017: Closing in on neurorepair in progressive multiple sclerosis. Mult Scler 2018; 24:696-700. [PMID: 29629605 DOI: 10.1177/1352458518768770] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND While there is now a multitude of potent medications for relapsing-remitting multiple sclerosis (RRMS), effective therapies targeting neurodegeneration in progressive multiple sclerosis types are still lacking. Stimulation of neurorepair in this disease remains a pathogenetically defined treatment goal. However, therapeutic progress is slowed by the still inadequate tool set to capture "regeneration/repair" in MS and to define appropriate outcomes in clinical trials. OBJECTIVES In this review, we discuss studies investigating promising regenerative agents for progressive MS which were recently presented during the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS)/Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) 2017 meeting in Paris.
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Affiliation(s)
- David Kremer
- Department of Neurology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Patrick Küry
- Department of Neurology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Hans-Peter Hartung
- Department of Neurology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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23
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Bahrami S, Gryz EA, Graversen JH, Troldborg A, Stengaard Pedersen K, Laska MJ. Immunomodulating peptides derived from different human endogenous retroviruses (HERVs) show dissimilar impact on pathogenesis of a multiple sclerosis animal disease model. Clin Immunol 2018; 191:37-43. [PMID: 29567431 DOI: 10.1016/j.clim.2018.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/16/2018] [Accepted: 03/16/2018] [Indexed: 02/07/2023]
Abstract
Retroviruses including Human Endogenous Retroviruses (HERVs), contain a conserved region with highly immunomodulatory functions in the transmembrane proteins in envelope gene (env) named immunosuppressive domain (ISU). In this report, we demonstrate that Env59-GP3 peptide holds therapeutic potential in a mouse model of myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE). The results show that this specific HERV-H derived ISU peptide, but not peptide derived from another env gene HERV-K, decreased the development of EAE in C57BL/6 mice, accompanied by reduced demyelination and inhibition of inflammatory cells. Moreover, here we tested the effect of peptides on macrophages differentiation. The treatment with Env59-GPS peptide modulate the pro-inflammatory M1 profile and anti-inflammatory M2 macrophages, being shown by inhibiting inflammatory M1 hallmark genes/cytokines expression and enhancing expression of M2 associated markers. These results demonstrate that Env59-GP3 ISU peptide has therapeutic potential in EAE possibly through inducing the polarization of M2 macrophages and inhibiting inflammatory responses.
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Affiliation(s)
- Shervin Bahrami
- Department of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark
| | | | | | - Anne Troldborg
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark; Department of Rheumatology, Aarhus University Hospital, 8000 Aarhus C, Denmark
| | - Kristian Stengaard Pedersen
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark; Department of Rheumatology, Aarhus University Hospital, 8000 Aarhus C, Denmark
| | - Magdalena Janina Laska
- Department of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark; Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark; Department of Rheumatology, Aarhus University Hospital, 8000 Aarhus C, Denmark.
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24
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Grandi N, Tramontano E. HERV Envelope Proteins: Physiological Role and Pathogenic Potential in Cancer and Autoimmunity. Front Microbiol 2018; 9:462. [PMID: 29593697 PMCID: PMC5861771 DOI: 10.3389/fmicb.2018.00462] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/27/2018] [Indexed: 12/29/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are relics of ancient infections accounting for about the 8% of our genome. Despite their persistence in human DNA led to the accumulation of mutations, HERVs are still contributing to the human transcriptome, and a growing number of findings suggests that their expression products may have a role in various diseases. Among HERV products, the envelope proteins (Env) are currently highly investigated for their pathogenic properties, which could likely be participating to several disorders with complex etiology, particularly in the contexts of autoimmunity and cancer. In fact, HERV Env proteins have been shown, on the one side, to trigger both innate and adaptive immunity, prompting inflammatory, cytotoxic and apoptotic reactions; and, on the other side, to prevent the immune response activation, presenting immunosuppressive properties and acting as immune downregulators. In addition, HERV Env proteins have been shown to induce abnormal cell-cell fusion, possibly contributing to tumor development and metastasizing processes. Remarkably, even highly defective HERV env genes and alternative env splicing variants can provide further mechanisms of pathogenesis. A well-known example is the HERV-K(HML2) env gene that, depending on the presence or the absence of a 292-bp deletion, can originate two proteins of different length (Np9 and Rec) proposed to have oncogenic properties. The understanding of their involvement in complex pathological disorders made HERV Env proteins potential targets for therapeutic interventions. Of note, a monoclonal antibody directed against a HERV-W Env is currently under clinical trial as therapeutic approach for multiple sclerosis, representing the first HERV-based treatment. The present review will focus on the current knowledge of the HERV Env expression, summarizing its role in human physiology and its possible pathogenic effects in various cancer and autoimmune disorders. It moreover analyzes HERV Env possible exploitation for the development of innovative therapeutic strategies.
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Affiliation(s)
- Nicole Grandi
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Enzo Tramontano
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Cagliari, Italy
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25
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Grandi N, Tramontano E. Type W Human Endogenous Retrovirus (HERV-W) Integrations and Their Mobilization by L1 Machinery: Contribution to the Human Transcriptome and Impact on the Host Physiopathology. Viruses 2017; 9:v9070162. [PMID: 28653997 PMCID: PMC5537654 DOI: 10.3390/v9070162] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 06/08/2017] [Accepted: 06/20/2017] [Indexed: 01/07/2023] Open
Abstract
Human Endogenous Retroviruses (HERVs) are ancient infection relics constituting ~8% of our DNA. While HERVs’ genomic characterization is still ongoing, impressive amounts of data have been obtained regarding their general expression across tissues. Among HERVs, one of the most studied is the W group, which is the sole HERV group specifically mobilized by the long interspersed element-1 (LINE-1) machinery, providing a source of novel insertions by retrotransposition of HERV-W processed pseudogenes, and comprising a member encoding a functional envelope protein coopted for human placentation. The HERV-W group has been intensively investigated for its putative role in several diseases, such as cancer, inflammation, and autoimmunity. Despite major interest in the link between HERV-W expression and human pathogenesis, no conclusive correlation has been demonstrated so far. In general, (i) the absence of a proper identification of the specific HERV-W sequences expressed in a given condition; and (ii) the lack of studies attempting to connect the various observations in the same experimental conditions are the major problems preventing the definitive assessment of the HERV-W impact on human physiopathology. In this review, we summarize the current knowledge on the HERV-W group presence within the human genome and its expression in physiological tissues as well as in the main pathological contexts.
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Affiliation(s)
- Nicole Grandi
- Department of Life and Environmental Sciences, University of Cagliari, Cittadella Universitaria di Monserrato SS554, 09042 Monserrato, Cagliari, Italy.
| | - Enzo Tramontano
- Department of Life and Environmental Sciences, University of Cagliari, Cittadella Universitaria di Monserrato SS554, 09042 Monserrato, Cagliari, Italy.
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), 09042 Monserrato, Cagliari, Italy.
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27
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Curtin F, Perron H, Faucard R, Porchet H, Lang AB. Treatment against human endogenous retrovirus: a possible personalized medicine approach for multiple sclerosis. Mol Diagn Ther 2016; 19:255-65. [PMID: 26376649 DOI: 10.1007/s40291-015-0166-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Human endogenous retroviruses (HERV) represent about 8 % of the human genome. Some of these genetic elements are expressed in pathological circumstances. A HERV protein, the multiple sclerosis-associated retrovirus (MSRV) envelope protein (MSRV-Env), is expressed in the blood and active brain lesions of multiple sclerosis (MS) patients. It possesses pro-inflammatory and myelinotoxic properties. The patterns of expression and pathogenic properties of MSRV-Env make it a relevant drug target for MS therapeutics-in particular for preventing neurodegeneration, a key component of progressive forms of MS. An immunoglobulin G4 monoclonal antibody (mAb), called GNbAC1, has been developed to neutralize this pathogenic target. After showing neutralizing effects in vitro and in mouse models of MS, GNbAC1 is now in phase II clinical development. MSRV-related biomarkers such as MSRV-Env and MSRV polymerase (MSRV-Pol) gene transcripts are overexpressed in the blood and cerebrospinal fluid of patients with MS. These biomarkers may have prognostic value for long-term MS evolution, and their transcription levels in blood decline during treatments with GNbAC1, which has also been reported in patients administered reference MS drugs such as natalizumab or interferon-β. GNbAC1 as a new MSRV-Env-antagonist mAb could be a specific and causal treatment for MS, with a particular application for progressive forms of the disease. For possible use in companion diagnostic tests, MSRV-associated biomarkers could open the door to a personalized therapeutic approach for MS.
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Affiliation(s)
- François Curtin
- GeNeuro SA, 18 Chemin des Aulx, Plan-les-Ouates, 1228, Geneva, Switzerland. .,Division of Clinical Pharmacology and Toxicology Division, Geneva University Hospital, Geneva, Switzerland.
| | - Hervé Perron
- GeNeuro SA, 18 Chemin des Aulx, Plan-les-Ouates, 1228, Geneva, Switzerland
| | - Raphael Faucard
- GeNeuro SA, 18 Chemin des Aulx, Plan-les-Ouates, 1228, Geneva, Switzerland
| | - Hervé Porchet
- GeNeuro SA, 18 Chemin des Aulx, Plan-les-Ouates, 1228, Geneva, Switzerland.,Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Alois B Lang
- GeNeuro SA, 18 Chemin des Aulx, Plan-les-Ouates, 1228, Geneva, Switzerland
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Fernández-Menéndez S, Fernández-Morán M, Fernández-Vega I, Pérez-Álvarez A, Villafani-Echazú J. Epstein-Barr virus and multiple sclerosis. From evidence to therapeutic strategies. J Neurol Sci 2016; 361:213-9. [PMID: 26810546 DOI: 10.1016/j.jns.2016.01.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/21/2015] [Accepted: 01/05/2016] [Indexed: 10/22/2022]
Abstract
Multiple sclerosis is caused by a complex interaction between genetic predisposition and environmental factors. Epstein-Barr virus (EBV) is an environmental risk factor that is strongly related to multiple sclerosis (MS), since EBV seropositivity is linked to a significant risk of developing MS. EBV may be involved in the pathogenesis of the disease and it is possibly a prerequisite for the development of MS. EBV infection persists in B-cells during the lifetime of the host and can modulate their function. In addition, MS patients might have a deficient capacity to eliminate latent EBV infection in the central nervous system and this would promote the accumulation of infected B cells. Several mechanisms of pathogenesis, including a direct and indirect function of infected B cells, have been postulated in inflammation and neurodegeneration. A relationship between EBV and human endogenous retroviruses in the pathogenesis of MS has also been reported. If EBV is important in the pathogenesis of MS, different therapeutic strategies seem possible for MS treatment.
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Affiliation(s)
| | - Marta Fernández-Morán
- Department of Neuropaediatrics, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Iván Fernández-Vega
- Pathology department (Neuropathology division), Hospital Universitario Araba, Álava, Spain
| | - Angel Pérez-Álvarez
- Department of Neurology, Hospital Universitario Central de Asturias, Oviedo, Spain
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MSRV envelope protein is a potent, endogenous and pathogenic agonist of human toll-like receptor 4: Relevance of GNbAC1 in multiple sclerosis treatment. J Neuroimmunol 2015; 291:29-38. [PMID: 26857492 DOI: 10.1016/j.jneuroim.2015.12.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/03/2015] [Accepted: 12/10/2015] [Indexed: 02/07/2023]
Abstract
Multiple sclerosis associated retrovirus envelope protein (MSRV-Env) was repeatedly detected in brain lesions and blood of multiple sclerosis (MS) patients. We performed the first pharmacological characterisation of MSRV-Env on recombinant and native human TLR4. MSRV-Env is a full and highly potent TLR4 agonist of endogenous origin. MSRV-Env induces TLR4-dependent pro-inflammatory stimulation of immune cells in vitro and in vivo, and impairs oligodendrocytes precursor cells differentiation to myelinating oligodendrocytes. MSRV-Env may play a role in chronic inflammation and impaired remyelination in MS. GNbAC1, a selective monoclonal antibody, antagonizes MSRV-Env pathogenic effects and represents an innovative therapeutic approach of MS.
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30
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Hurst TP, Magiorkinis G. Activation of the innate immune response by endogenous retroviruses. J Gen Virol 2015; 96:1207-1218. [PMID: 26068187 DOI: 10.1099/jgv.0.000017] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The human genome comprises 8 % endogenous retroviruses (ERVs), the majority of which are defective due to deleterious mutations. Nonetheless, transcripts of ERVs are found in most tissues, and these transcripts could either be reverse transcribed to generate ssDNA or expressed to generate proteins. Thus, the expression of ERVs could produce nucleic acids or proteins with viral signatures, much like the pathogen-associated molecular patterns of exogenous viruses, which would enable them to be detected by the innate immune system. The activation of some pattern recognition receptors (PRRs) in response to ERVs has been described in mice and in the context of human autoimmune diseases. Here, we review the evidence for detection of ERVs by PRRs and the resultant activation of innate immune signalling. This is an emerging area of research within the field of innate antiviral immunity, showing how ERVs could initiate immune signalling pathways and might have implications for numerous inflammatory diseases.
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Affiliation(s)
- Tara P Hurst
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK
| | - Gkikas Magiorkinis
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK
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31
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32
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Curtin F, Perron H, Kromminga A, Porchet H, Lang AB. Preclinical and early clinical development of GNbAC1, a humanized IgG4 monoclonal antibody targeting endogenous retroviral MSRV-Env protein. MAbs 2015; 7:265-75. [PMID: 25427053 PMCID: PMC4623301 DOI: 10.4161/19420862.2014.985021] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 10/15/2014] [Accepted: 10/31/2014] [Indexed: 11/19/2022] Open
Abstract
Monoclonal antibodies (mAbs) play an increasing important role in the therapeutic armamentarium against multiple sclerosis (MS), an inflammatory and degenerative disorder of the central nervous system. Most of the mAbs currently developed for MS are immunomodulators blocking the inflammatory immune process. In contrast with mAbs targeting immune function, GNbAC1, a humanized IgG4 mAb, targets the multiple sclerosis associated retrovirus envelope (MSRV-Env) protein, an upstream factor in the pathophysiology of MS. MSRV-Env protein is of endogenous retroviral origin, expressed in MS brain lesions, and it is pro-inflammatory and toxic to the remyelination process, by preventing the differentiation of oligodendrocyte precursor cells. We present the preclinical and early clinical development results of GNbAC1. The specificity of GNbAC1 for its endogenous retroviral target is described. Efficacy of different mAb versions of GNbAC1 were assessed in MSRV-Env induced experimental allergic encephalitis (EAE), an animal model of MS. Because the target MSRV-Env is not expressed in animals, no relevant animal model exists for a proper in vivo toxicological program. An off-target 2-week toxicity study in mice was thus performed, and it showed an absence of safety risk. Additional in vitro analyses showed an absence of complement or antibody-dependent cytotoxicity as well as a low level of cross-reactivity to human tissues. The first-in-man clinical study in 33 healthy subjects and a long-term clinical study in 10 MS patients showed that GNbAC1 is well tolerated in humans without induction of immunogenicity and that it induces a pharmacodynamic response on MSRV biomarkers. These initial results suggest that the mAb GNbAC1 could be a safe long-term treatment for patients with MS with a unique therapeutic mechanism of action.
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Key Words
- ADCC, antibody-dependent cell-mediated cytotoxicity
- AE, adverse events
- AUC, area under the curve
- BLAST, Basic Local Alignment Search Tool
- CDC, complement-dependent cytotoxicity
- CDR, complementarity-determining regions
- Cmax, maximal concentration
- Cmin, minimal concentration
- HERV-W
- HERV-W, human endogenous retrovirus type W
- HLA, human leukocyte antigen
- MOG, myelin oligodendrocyte glycoprotein
- MS, multiple sclerosis
- MSRV
- MSRV, multiple sclerosis associated retrovirus
- MSRV-Env, multiple sclerosis associated retrovirus envelope protein
- PBMC, peripheral blood mononuclear cell
- SAE, serious adverse event
- SU, surface domain
- Syncytin
- TLR4, Toll-like receptor 4
- ch-GNbAC1, chimeric version of mAb GNbAC1
- drug safety
- human endogenous retrovirus
- mAb, monoclonal antibody
- monoclonal antibody
- mu-GNbAC1, murine version of mAb GNbAC1
- multiple sclerosis
- neurotoxicity
- toxicology
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MESH Headings
- Animals
- Antibodies, Monoclonal, Humanized/administration & dosage
- Antibodies, Monoclonal, Humanized/adverse effects
- Antibodies, Monoclonal, Humanized/immunology
- Antibody Specificity
- Encephalomyelitis, Autoimmune, Experimental/drug therapy
- Encephalomyelitis, Autoimmune, Experimental/immunology
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Endogenous Retroviruses/immunology
- Female
- Gene Products, env/immunology
- HEK293 Cells
- Humans
- Immunoglobulin G/administration & dosage
- Immunoglobulin G/adverse effects
- Immunoglobulin G/immunology
- Male
- Mice
- Multiple Sclerosis/drug therapy
- Multiple Sclerosis/immunology
- Multiple Sclerosis/pathology
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Affiliation(s)
- François Curtin
- GeNeuro SA; Plan-les-Ouates/Geneva, Switzerland
- Division of Clinical Pharmacology and Toxicology; University of Geneva; Geneva, Switzerland
| | | | - Arno Kromminga
- Institute of Immunology; University Kiel; Kiel, Germany
- IPM Biotech; Hamburg, Germany
| | - Hervé Porchet
- GeNeuro SA; Plan-les-Ouates/Geneva, Switzerland
- Department of Pharmacology; University of Pretoria; Pretoria, South Africa
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Douville RN, Nath A. Human endogenous retroviruses and the nervous system. HANDBOOK OF CLINICAL NEUROLOGY 2014; 123:465-85. [PMID: 25015500 DOI: 10.1016/b978-0-444-53488-0.00022-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Renée N Douville
- Department of Microbiology, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Avindra Nath
- Section of Infections of the Nervous System, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, USA.
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Neuroendocrine immunoregulation in multiple sclerosis. Clin Dev Immunol 2013; 2013:705232. [PMID: 24382974 PMCID: PMC3870621 DOI: 10.1155/2013/705232] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/29/2013] [Accepted: 09/30/2013] [Indexed: 12/03/2022]
Abstract
Currently, it is generally accepted that multiple sclerosis (MS) is a complex multifactorial disease involving genetic and environmental factors affecting the autoreactive immune responses that lead to damage of myelin. In this respect, intrinsic or extrinsic factors such as emotional, psychological, traumatic, or inflammatory stress as well as a variety of other lifestyle interventions can influence the neuroendocrine system. On its turn, it has been demonstrated that the neuroendocrine system has immunomodulatory potential. Moreover, the neuroendocrine and immune systems communicate bidirectionally via shared receptors and shared messenger molecules, variously called hormones, neurotransmitters, or cytokines. Discrepancies at any level can therefore lead to changes in susceptibility and to severity of several autoimmune and inflammatory diseases. Here we provide an overview of the complex system of crosstalk between the neuroendocrine and immune system as well as reported dysfunctions involved in the pathogenesis of autoimmunity, including MS. Finally, possible strategies to intervene with the neuroendocrine-immune system for MS patient management will be discussed. Ultimately, a better understanding of the interactions between the neuroendocrine system and the immune system can open up new therapeutic approaches for the treatment of MS as well as other autoimmune diseases.
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Lossius A, Johansen JN, Torkildsen Ø, Vartdal F, Holmøy T. Epstein-Barr virus in systemic lupus erythematosus, rheumatoid arthritis and multiple sclerosis—association and causation. Viruses 2013; 4:3701-30. [PMID: 23342374 PMCID: PMC3528287 DOI: 10.3390/v4123701] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Epidemiological data suggest that the Epstein-Barr virus (EBV) is associated with several autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis and multiple sclerosis. However, it is not clear whether EBV plays a role in the pathogenesis of these diseases, and if so, by which mechanisms the virus may contribute. In this review, we discuss possible viral and immunological mechanisms that might explain associations between EBV and autoimmune diseases and whether these associations represent causes or effects of inflammation and autoimmunity.
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Affiliation(s)
- Andreas Lossius
- Institute of Immunology, Oslo University Hospital Rikshospitalet, Oslo, Norway.
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37
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Perron H, Germi R, Bernard C, Garcia-Montojo M, Deluen C, Farinelli L, Faucard R, Veas F, Stefas I, Fabriek BO, Van-Horssen J, Van-der-Valk P, Gerdil C, Mancuso R, Saresella M, Clerici M, Marcel S, Creange A, Cavaretta R, Caputo D, Arru G, Morand P, Lang AB, Sotgiu S, Ruprecht K, Rieckmann P, Villoslada P, Chofflon M, Boucraut J, Pelletier J, Hartung HP. Human endogenous retrovirus type W envelope expression in blood and brain cells provides new insights into multiple sclerosis disease. Mult Scler 2012; 18:1721-36. [PMID: 22457345 PMCID: PMC3573672 DOI: 10.1177/1352458512441381] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background: The envelope protein from multiple sclerosis (MS) associated retroviral element (MSRV), a member of the Human Endogenous Retroviral family ‘W’ (HERV-W), induces dysimmunity and inflammation. Objective: The objective of this study was to confirm and specify the association between HERV-W/MSRV envelope (Env) expression and MS. Methods: 103 MS, 199 healthy controls (HC) and controls with other neurological diseases (28), chronic infections (30) or autoimmunity (30) were analysed with an immunoassay detecting Env in serum. Env RNA or DNA copy numbers in peripheral blood mononuclear cells (PBMC) were determined by a quantitative polymerase chain reaction (PCR). Env was detected by immunohistology in the brains of patients with MS with three specific monoclonals. Results: Env antigen was detected in a serum of 73% of patients with MS with similar prevalence in all clinical forms, and not in chronic infection, systemic lupus, most other neurological diseases and healthy donors (p<0.01). Cases with chronic inflammatory demyelinating polyneuropathy (5/8) and rare HC (4/103) were positive. RNA expression in PBMC and DNA copy numbers were significantly elevated in patients with MS versus HC (p<0.001). In patients with MS, DNA copy numbers were significantly increased in chronic progressive MS (secondary progressive MS vs relapsing–remitting MS (RRMS) p<0.001; primary progressive MS vs RRMS –<0.02). Env protein was evidenced in macrophages within MS brain lesions with particular concentrations around vascular elements. Conclusion: The association between MS disease and the MSRV-type HERV-W element now appears quite strong, as evidenced ex-vivo from serum and PBMC with post-mortem confirmation in brain lesions. Chronic progressive MS, RRMS and clinically isolated syndrome show different ELISA (Enzyme-Linked Immunosorbent Assay) and/or PCR profiles suggestive of an increase with disease evolution, and amplicon sequencing confirms the association with particular HERV-W elements.
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Tropism, cytotoxicity, and inflammatory properties of two envelope genes of murine leukemia virus type-endogenous retroviruses of C57BL/6J mice. Mediators Inflamm 2011; 2011:509604. [PMID: 21772664 PMCID: PMC3134291 DOI: 10.1155/2011/509604] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Accepted: 03/09/2011] [Indexed: 12/16/2022] Open
Abstract
Envelope (env) proteins of certain endogenous retroviruses (ERVs) participate in various pathophysiological processes. In this study, we characterized pathophysiologic properties of two murine leukemia virus-type ERV (MuLV-ERV) env genes cloned from the ovary of C57BL/6J mice. The two env genes (named ENVOV1 and ENVOV2), with 1,926 bp coding region, originated from two MuLV-ERV loci on chromosomes 8 and 18, respectively. ENVOV1 and ENVOV2 were ~75 kDa and predominantly expressed on the cell membrane. They were capable of producing pseudotype murine leukemia virus virions. Tropism trait and infectivity of ENVOV2 were similar to the polytropic env; however, ENVOV1 had very low level of infectivity. Overexpression of ENVOV2, but not ENVOV1, exerted cytotoxic effects and induced expression of COX-2, IL-1β, IL-6, and iNOS. These findings suggest that the ENVOV1 and ENVOV2 are capable of serving as an env protein for virion assembly, and they exert differential cytotoxicity and modulation of inflammatory mediators.
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The human microbiome in multiple sclerosis: pathogenic or protective constituents? Can J Neurol Sci 2011; 37 Suppl 2:S24-33. [PMID: 21246932 DOI: 10.1017/s031716710002240x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The human microbiome is comprised of commensal and pathogenic microorganisms, which exert diverse effects in close proximity to the site of intection as well as in remote tissues through immune-mediated mechanisms. Multiple infectious agents have been implicated in the pathogenesis of multiple sclerosis (MS) with variable findings depending on the agent, techniques, and disease phenotype. Herein, the contributions of individual infectious agents to MS and their effects on the immune and nervous systems are reviewed, focusing on herpes viruses, coronaviruses, retroviruses, and synchronic infections. While infectious agents are often assumed to be pathogenic, their effects might also be beneficial to the host in the long-term, depending on age and the type of immunogen/pathogen exposure, as proposed by the hygiene hypothesis. The human microbiome has potential impact on future diagnostic and therapeutic issues in MS.
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Perron H, Lang A. The human endogenous retrovirus link between genes and environment in multiple sclerosis and in multifactorial diseases associating neuroinflammation. Clin Rev Allergy Immunol 2010; 39:51-61. [PMID: 19697163 DOI: 10.1007/s12016-009-8170-x] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Endogenous retroviruses represent about 8% of the human genome and belong to the superfamily of transposable and retrotransposable genetic elements. Altogether, these mobile genetic elements and their numerous inactivated "junk" sequences represent nearly one half of the human DNA. Nonetheless, a significant part of this "non-conventional" genome has retained potential activity. Epigenetic control is notably involved in silencing most of these genetic elements but certain environmental factors such as viruses are known to dysregulate their expression in susceptible cells. More particularly, embryonal cells with limited gene methylation are most susceptible to uncontrolled activation of these mobile genetic elements by, e.g., viral infections. In particular, certain viruses transactivate promoters from endogenous retroviral family type W (HERV-W). HERV-W RNA was first isolated in circulating viral particles (Multiple Sclerosis-associated RetroViral element, MSRV) that have been associated with the evolution and prognosis of multiple sclerosis. HERV-W elements encode a powerful immunopathogenic envelope protein (ENV) that activates a pro-inflammatory and autoimmune cascade through interaction with Toll-like receptor 4 on immune cells. This ENV protein has repeatedly been detected in MS brain lesions and may be involved in other diseases. Epigenetic factors controlling HERV-W ENV protein expression then reveal critical. This review addresses the gene-environment epigenetic interface of such HERV-W elements and its potential involvement in disease.
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Affiliation(s)
- Hervé Perron
- GeNeuro, 18, Chemin des Aulx, 1228, Plan-Les Ouates, Geneva, Switzerland.
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Roebke C, Wahl S, Laufer G, Stadelmann C, Sauter M, Mueller-Lantzsch N, Mayer J, Ruprecht K. An N-terminally truncated envelope protein encoded by a human endogenous retrovirus W locus on chromosome Xq22.3. Retrovirology 2010; 7:69. [PMID: 20735848 PMCID: PMC2936387 DOI: 10.1186/1742-4690-7-69] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 08/24/2010] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND We previously showed that the envelope (env) sequence of a human endogenous retrovirus (HERV)-W locus on chromosome Xq22.3 is transcribed in human peripheral blood mononuclear cells. The env open reading frame (ORF) of this locus is interrupted by a premature stop at codon 39, but otherwise harbors a long ORF for an N-terminally truncated 475 amino acid Env protein, starting at an in-frame ATG at codon 68. We set out to characterize the protein encoded by that ORF. RESULTS Transient expression of the 475 amino acid Xq22.3 HERV-W env ORF produced an N-terminally truncated HERV-W Env protein, as detected by the monoclonal anti-HERV-W Env antibodies 6A2B2 and 13H5A5. Remarkably, reversion of the stop at codon 39 in Xq22.3 HERV-W env reconstituted a full-length HERV-W Xq22.3 Env protein. Similar to the full-length HERV-W Env protein Syncytin-1, reconstituted full-length Xq22.3 HERV-W Env is glycosylated, forms oligomers, and is expressed at the cell surface. In contrast, Xq22.3 HERV-W Env is unglycosylated, does not form oligomers, and is located intracellularly, probably due to lack of a signal peptide. Finally, we reconfirm by immunohistochemistry that monoclonal antibody 6A2B2 detects an antigen expressed in placenta and multiple sclerosis brain lesions. CONCLUSIONS A partially defective HERV-W env gene located on chromosome Xq22.3, which we propose to designate ERVWE2, has retained coding capacity and can produce ex vivo an N-terminally truncated Env protein, named N-Trenv. Detection of an antigen by 6A2B2 in placenta and multiple sclerosis lesions opens the possibility that N-Trenv could be expressed in vivo. More generally, our findings are compatible with the idea that defective HERV elements may be capable of producing incomplete HERV proteins that, speculatively, may exert functions in human physiology or pathology.
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Affiliation(s)
- Christina Roebke
- Institut für Virologie, Gebäude 47, Universitätsklinikum des Saarlandes, 66421 Homburg, Germany
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Antony JM, Deslauriers AM, Bhat RK, Ellestad KK, Power C. Human endogenous retroviruses and multiple sclerosis: innocent bystanders or disease determinants? Biochim Biophys Acta Mol Basis Dis 2010; 1812:162-76. [PMID: 20696240 PMCID: PMC7172332 DOI: 10.1016/j.bbadis.2010.07.016] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 07/14/2010] [Accepted: 07/26/2010] [Indexed: 12/21/2022]
Abstract
Human endogenous retroviruses (HERVs) constitute 5–8% of human genomic DNA and are replication incompetent despite expression of individual HERV genes from different chromosomal loci depending on the specific tissue. Several HERV genes have been detected as transcripts and proteins in the central nervous system, frequently in the context of neuroinflammation. The HERV-W family has received substantial attention in large part because of associations with diverse syndromes including multiple sclerosis (MS) and several psychiatric disorders. A HERV-W-related retroelement, multiple sclerosis retrovirus (MSRV), has been reported in MS patients to be both a biomarker as well as an effector of aberrant immune responses. HERV-H and HERV-K have also been implicated in MS and other neurological diseases but await delineation of their contributions to disease. The HERV-W envelope-encoded glycosylated protein, syncytin-1, is encoded by chromosome 7q21 and exhibits increased glial expression within MS lesions. Overexpression of syncytin-1 in glia induces endoplasmic reticulum stress leading to neuroinflammation and the induction of free radicals, which damage proximate cells. Syncytin-1's receptor, ASCT1 is a neutral amino acid transporter expressed on glia and is suppressed in white matter of MS patients. Of interest, antioxidants ameliorate syncytin-1's neuropathogenic effects raising the possibility of using these agents as therapeutics for neuroinflammatory diseases. Given the multiple insertion sites of HERV genes as complete and incomplete open reading frames, together with their differing capacity to be expressed and the complexities of individual HERVs as both disease markers and bioactive effectors, HERV biology is a compelling area for understanding neuropathogenic mechanisms and developing new therapeutic strategies.
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43
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Jean-Gilles L, Gran B, Constantinescu CS. Interaction between cytokines, cannabinoids and the nervous system. Immunobiology 2010; 215:606-10. [DOI: 10.1016/j.imbio.2009.12.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 12/16/2009] [Accepted: 12/17/2009] [Indexed: 12/19/2022]
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Perron H, Bernard C, Bertrand JB, Lang AB, Popa I, Sanhadji K, Portoukalian J. Endogenous retroviral genes, Herpesviruses and gender in Multiple Sclerosis. J Neurol Sci 2009; 286:65-72. [DOI: 10.1016/j.jns.2009.04.034] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 04/02/2009] [Accepted: 04/14/2009] [Indexed: 01/13/2023]
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Laufer G, Mayer J, Mueller BF, Mueller-Lantzsch N, Ruprecht K. Analysis of transcribed human endogenous retrovirus W env loci clarifies the origin of multiple sclerosis-associated retrovirus env sequences. Retrovirology 2009; 6:37. [PMID: 19368703 PMCID: PMC2672075 DOI: 10.1186/1742-4690-6-37] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 04/15/2009] [Indexed: 12/19/2022] Open
Abstract
Background Multiple sclerosis-associated retrovirus (MSRV) RNA sequences have been detected in patients with multiple sclerosis (MS) and are related to the multi-copy human endogenous retrovirus family type W (HERV-W). Only one HERV-W locus (ERVWE1) codes for a complete HERV-W Env protein (Syncytin-1). Syncytin-1 and the putative MSRV Env protein have been involved in the pathogenesis of MS. The origin of MSRV and its precise relation to HERV-W were hitherto unknown. Results By mapping HERV-W env cDNA sequences (n = 332) from peripheral blood mononuclear cells of patients with MS and healthy controls onto individual genomic HERV-W env elements, we identified seven transcribed HERV-W env loci in these cells, including ERVWE1. Transcriptional activity of individual HERV-W env elements did not significantly differ between patients with MS and controls. Remarkably, almost 30% of HERV-W env cDNAs were recombined sequences that most likely arose in vitro between transcripts from different HERV-W env elements. Re-analysis of published MSRV env sequences revealed that all of them can be explained as originating from genomic HERV-W env loci or recombinations among them. In particular, a MSRV env clone previously used for the generation of monoclonal antibody 6A2B2, detecting an antigen in MS brain lesions, appears to be derived from a HERV-W env locus on chromosome Xq22.3. This locus harbors a long open reading frame for an N-terminally truncated HERV-W Env protein. Conclusion Our data clarify the origin of MSRV env sequences, have important implications for the status of MSRV, and open the possibility that a protein encoded by a HERV-W env element on chromosome Xq22.3 may be expressed in MS brain lesions.
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Affiliation(s)
- Georg Laufer
- Institute of Virology, Saarland University Hospital, Homburg, Germany.
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47
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Saresella M, Rolland A, Marventano I, Cavarretta R, Caputo D, Marche P, Perron H, Clerici M. Multiple sclerosis-associated retroviral agent (MSRV)-stimulated cytokine production in patients with relapsing-remitting multiple sclerosis. Mult Scler 2009; 15:443-7. [DOI: 10.1177/1352458508100840] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background Human endogenous retroviruses are suggested to play a pathogenic role in multiple sclerosis (MS); one of such retroviruses, the MS-associated retroviral agent (MSRV) has repeatedly been isolated in MS patients. Objective and methods We analyzed cytokine profiles in MSRV envelope protein (MSRV ENV-SU)-stimulated peripheral blood mononuclear cells of 30 relapsing-remitting MS patients with either acute (AMS) ( n = 13) or stable (SMS) ( n = 17) disease. Results suggest that MSRV ENV-SU induces the production of inflammatory cytokines, including tumor necrosis factor-α ( P < 0.05) and interferon-γ ( P < 0.004) in AMS patients and of interleukin-10 ( P < 0.05), an inflammation-dampening cytokine, in SMS individuals. Conclusions These data strengthen the hypothesis indicating that MSRV could be involved in the pathogenesis of MS.
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Affiliation(s)
- M Saresella
- Laboratory of Molecular Medicine and Biotechnology, Don C. Gnocchi ONLUS Foundation IRCCS, Via Capecelatro, 66, Milano 20148, Italy
| | - A Rolland
- Laboratoire d’Immunochimie,CEA/INSERUM-U548, 17 rue des Martyrs 38054 Grenoble, France
| | - I Marventano
- Laboratory of Molecular Medicine and Biotechnology, Don C. Gnocchi ONLUS Foundation IRCCS, Via Capecelatro, 66, Milano 20148, Italy
| | - R Cavarretta
- Multiple Sclerosis Unit, Don C. Gnocchi ONLUS Foundation, IRCCS, Via Capecelatro, 66, Milano 20148, Italy
| | - D Caputo
- Multiple Sclerosis Unit, Don C. Gnocchi ONLUS Foundation, IRCCS, Via Capecelatro, 66, Milano 20148, Italy
| | - P Marche
- Laboratoire d’Immunochimie,CEA/INSERUM-U548, 17 rue des Martyrs 38054 Grenoble, France
| | - H Perron
- GeNeuro, Geneva; 1228 Plan-Lesouates, Switzerland
| | - M Clerici
- Laboratory of Molecular Medicine and Biotechnology, Don C. Gnocchi ONLUS Foundation IRCCS, Via Capecelatro, 66, Milano 20148, Italy; Chair of Immunology, Department of Biomedical Sciences and Technologies, University of Milano, Via Fratelli Cervi 93, Milano 20090, Italy
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48
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Alvarez-Lafuente R, García-Montojo M, De Las Heras V, Domínguez-Mozo MI, Bartolome M, Benito-Martin MS, Arroyo R. Herpesviruses and human endogenous retroviral sequences in the cerebrospinal fluid of multiple sclerosis patients. Mult Scler 2008; 14:595-601. [PMID: 18566025 DOI: 10.1177/1352458507086425] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To analyze the possible role of human herpesvirus (HHVs) and human endogenous retroviruses (HERVs) infection in multiple sclerosis (MS) pathogenesis. METHODS A total of 92 cerebrospinal fluid (CSF) samples were collected: 48 from MS patients at the first clinically evident demyelinating event, 23 from patients with other inflammatory neurological diseases (OINDs) and 21 from patients with other non-inflammatory neurological diseases (ONINDs). Total DNA and RNA were isolated, and the prevalences and viral loads of herpes simplex virus (HSV), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), HHV-6, HERV-H and HERV-W in the CSF of MS patients and controls were evaluated using a quantitative real-time polymerase chain reaction assay. RESULTS (i) For HSV, 1/48 (2.1%, 86 copies/ml of CSF) MS patients and 1/23 (4.3%, 115.2 copies/ml of CSF) OIND patients (a myelitis case) had HSV sequences in the CSF; (ii) for EBV, only 1/48 (2.1%, 72 copies/ml of CSF) MS patients was positive for EBV; (iii) for HHV-6, only 5/48 (10.4%) MS patients had HHV-6 genomes in their CSF (128.1 copies/ml of CSF); (iv) we did not find any positive cases for VZV, CMV, HERV-H and HERV-W among MS patients or controls; (v) no cases of co-infections were found; (vi) the whole prevalence of HHVs was 7/48 (14.6%) for MS patients and 1/44 (2.3%) for controls (p = 0.038). CONCLUSION The findings described here show that HHV infection is more frequent in the CSF of MS patients than in patients with other neurological diseases; however, only HHV-6 seems to be involved in the pathogenesis of MS in a subset of patients.
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49
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Voisset C, Weiss RA, Griffiths DJ. Human RNA "rumor" viruses: the search for novel human retroviruses in chronic disease. Microbiol Mol Biol Rev 2008; 72:157-96, table of contents. [PMID: 18322038 PMCID: PMC2268285 DOI: 10.1128/mmbr.00033-07] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Retroviruses are an important group of pathogens that cause a variety of diseases in humans and animals. Four human retroviruses are currently known, including human immunodeficiency virus type 1, which causes AIDS, and human T-lymphotropic virus type 1, which causes cancer and inflammatory disease. For many years, there have been sporadic reports of additional human retroviral infections, particularly in cancer and other chronic diseases. Unfortunately, many of these putative viruses remain unproven and controversial, and some retrovirologists have dismissed them as merely "human rumor viruses." Work in this field was last reviewed in depth in 1984, and since then, the molecular techniques available for identifying and characterizing retroviruses have improved enormously in sensitivity. The advent of PCR in particular has dramatically enhanced our ability to detect novel viral sequences in human tissues. However, DNA amplification techniques have also increased the potential for false-positive detection due to contamination. In addition, the presence of many families of human endogenous retroviruses (HERVs) within our DNA can obstruct attempts to identify and validate novel human retroviruses. Here, we aim to bring together the data on "novel" retroviral infections in humans by critically examining the evidence for those putative viruses that have been linked with disease and the likelihood that they represent genuine human infections. We provide a background to the field and a discussion of potential confounding factors along with some technical guidelines. In addition, some of the difficulties associated with obtaining formal proof of causation for common or ubiquitous agents such as HERVs are discussed.
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Affiliation(s)
- Cécile Voisset
- CNRS-UMR8161, Institut de Biologie de Lille et Institut Pasteur de Lille, Lille, France
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50
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Abstract
Endogenous retroviruses (ERVs) integrated into human genome after cross-species infectious events millions of years ago. Few of the ERVs retain the basic structure of the integrated proviral form of infectious retroviruses. Human endogenous retroviruses (HERVs) represent a key molecular link between the host genome and infectious viral particles. They constitute a large reservoir of viral genes that could be activated by various factors such as mutations or carcinogenic chemical exposures and so forth. Endogenous retroviruses are transmitted genetically in a Mendelian fashion through the germline as proviral DNA. Expression pattern of HERVs can influence the outcome of their presence in many forms, which can be either beneficial or detrimental to the host. ERVs have been reported to play a role in both human physiology and human pathology. Along with their expression in many disease conditions, they have also been reported to be expressed on normal peripheral blood lymphocytes, salivary glands and keratinocytes.
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Affiliation(s)
- Sunit Kumar Singh
- Center for Cellular and Molecular Biology, Section of Infectious Diseases, Hyderabad, India.
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