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Van Horssen J.,VU University Amsterdam | Van Der Pol S.,VU University Amsterdam | Nijland P.,VU University Amsterdam | Amor S.,VU University Amsterdam | And 3 more authors.
Multiple Sclerosis and Related Disorders | Year: 2016

Background objective: Attempts to identify a causative agent of Multiple Sclerosis (MS) among environmental viruses have consistently failed suggesting that development of MS is a result from gene-environment interactions. A new pathogenic player within human genes, a human endogenous retrovirus (HERV) was identified from MS cells, named MS-associated retrovirus element (MSRV) and unveiled homologous multicopy HERVs (HERV-W). As independent studies revealed biological features of HERV-W on immune-mediated inflammation and on remyelinating cells, the present study characterized the presence of HERV-W envelope protein (MSRV-Env) at the cellular level, in different MS lesion stages to extend and validate previous studies. Methods: Immunohistological analysis of HERV-W envelope cellular expression in different lesion stages from a cohort of MS brains versus controls, using well-characterized and highly specific monoclonal antibodies. Results: HERV-W envelope protein was detected in all MS brains and quite essentially in lesions. Immunohistochemistry showed dominant expression in macrophages and microglia, coinciding with areas of active demyelination, spread over the active lesions, or limited to the rim of active microglia in chronic active lesions or in few surviving astrocytes of inactive plaques. Weak expression was seen in MS normal appearing white matter. In active plaques, few lymphoid cells and astrocytes were also stained. This HERV-W expression was not observed in control brains. Interpretation: HERV-W was expressed in demyelinated lesions from MS brains, which were all positive for this endogenous pathogenic protein. Pronounced HERV-W immunoreactivity in active MS lesions was intimately associated with areas of active demyelination throughout the successive stages of lesion evolution in MS brains. Based on its pathogenic potential, this HERV-W (MSRV) endogenous toxin thus appears to be a novel therapeutic target in MS. It also has a unique positioning as an early and lifelong expressed pathogenic agonist, acting upstream the pathways in which dysregulated physiological effectors are usually targeted by present therapeutic strategies for MS. © 2016 The Authors. Published by Elsevier B.V.

Perron H.,Geneuro | Perron H.,University of Lyon | Dougier-Reynaud H.-L.,Joseph Fourier University | Lomparski C.,Joseph Fourier University | And 9 more authors.
PLoS ONE | Year: 2013

Multiple sclerosis (MS) is a complex multifactorial disease of the central nervous system (CNS) for which animal models have mainly addressed downstream immunopathology but not potential inducers of autoimmunity. In the absence of a pathogen known to cause neuroinflammation in MS, Mycobacterial lysate is commonly used in the form of complete Freund's adjuvant to induce autoimmunity to myelin proteins in Experimental Allergic Encephalomyelitis (EAE), an animal model for MS. The present study demonstrates that a protein from the human endogenous retrovirus HERV-W family (MSRV-Env) can be used instead of mycobacterial lysate to induce autoimmunity and EAE in mice injected with MOG, with typical anti-myelin response and CNS lesions normally seen in this model. MSRV-Env was shown to induce proinflammatory response in human macrophage cells through TLR4 activation pathway. The present results demonstrate a similar activation of murine dendritic cells and show the ability of MSRV-Env to trigger EAE in mice. In previous studies, MSRV-Env protein was reproducibly detected in MS brain lesions within microglia and perivascular macrophages. The present results are therefore likely to provide a model for MS, in which the upstream adjuvant triggering neuroinflammation is the one detected in MS active lesions. This model now allows pre-clinical studies with therapeutic agents targeting this endogenous retroviral protein in MS. © 2013 Perron et al.

Leboyer M.,AP HP | Leboyer M.,French Institute of Health and Medical Research | Leboyer M.,University Paris - Sud | Leboyer M.,National Science Foundation | And 4 more authors.
World Journal of Biological Psychiatry | Year: 2013

Objectives. Provide a synthetic review of recent studies evidencing an association between human endogenous retrovirus-W (HERV-W) and schizophrenia. Methods. Bibliography analysis and contextual synthesis. Results. Epidemiological studies suggest that the aetiology of schizophrenia is complex and involves a complex interplay of genetic and environmental factors such as infections. Eight percentof the human genome consists of human endogenous retroviruses (HERV), and this part of the genome was previously thought to be without importance, but new research has refuted this. HERVs share similarities with viruses and it is assumed that HERVs are present in the genome as a result of retroviruses infecting germ line cells many million years ago. A specific type of HERVs, called HERV-W, has through several recent studies been associated with schizophrenia. Elevated transcription of HERV-W elements has been documented, and antigens of HERV-W envelope and capsid proteins have been found in blood samples from patients. Viruses that have been implicated in pathology of schizophrenia, such as herpes and influenza, have been shown to activate HERV-W elements, and such activation has been associated with elevated biomarkers of systemic inflammation. New research indicates that HERV-W may be an important genetic factor interplaying with the environmental risk factor of infections and that, through this, HERV-W may be important for disease pathogenesis. Conclusions. A lifelong scenario of a detrimental interaction between infectious agents and HERV-W genes may decipher the actual development and course of schizophrenia. Further research is needed to find out if specific treatment strategies could reduce the expression of HERV-W and if this will be associated with remission. © 2013 Informa Healthcare.

Perron H.,Geneuro | Perron H.,University of Lyon | Hamdani N.,French Institute of Health and Medical Research | Hamdani N.,University Paris Est Creteil | And 31 more authors.
Translational Psychiatry | Year: 2012

Epidemiological and genome-wide association studies of severe psychiatric disorders such as schizophrenia (SZ) and bipolar disorder (BD), suggest complex interactions between multiple genetic elements and environmental factors. The involvement of genetic elements such as Human Endogenous Retroviruses type W family (HERV-W) has consistently been associated with SZ. HERV-W envelope gene (env) is activated by environmental factors and encodes a protein displaying inflammation and neurotoxicity. The present study addressed the molecular characteristics of HERV-W env in SZ and BD. Hundred and thirty-six patients, 91 with BD, 45 with SZ and 73 healthy controls (HC) were included. HERV-W env transcription was found to be elevated in BD (P<10-4) and in SZ (P=0.012) as compared with HC, but with higher values in BD than in SZ group (P=0.01). The corresponding DNA copy number was paradoxically lower in the genome of patients with BD (P=0.0016) or SZ (P=0.0003) than in HC. Differences in nucleotide sequence of HERV-W env were found between patients with SZ and BD as compared with HC, as well as between SZ and BD. The molecular characteristics of HERV-W env also differ from what was observed in Multiple Sclerosis (MS) and may represent distinct features of the genome of patients with BD and SZ. The seroprevalence for Toxoplasma gondii yielded low but significant association with HERV-W transcriptional level in a subgroup of BD and SZ, suggesting a potential role in particular patients. A global hypothesis of mechanisms inducing such major psychoses is discussed, placing HERV-W at the crossroads between environmental, genetic and immunological factors. Thus, particular infections would act as activators of HERV-W elements in earliest life, resulting in the production of an HERV-W envelope protein, which then stimulates pro-inflammatory and neurotoxic cascades. This hypothesis needs to be further explored as it may yield major changes in our understanding and treatment of severe psychotic disorders. © 2012 Macmillan Publishers Limited All rights reserved.

Perron H.,Geneuro | Perron H.,University of Lyon | Germi R.,University Hospital | Bernard C.,Geneuro | And 31 more authors.
Multiple Sclerosis Journal | Year: 2012

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. © The Author(s) 2012.

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