Multiple sclerosis is linked to Epstein-Barr virus infection

Defective Integrator activity shapes the transcriptome of patients with multiple sclerosis

HP1α/CBX5 is an epigenetic regulator with a suspected role in multiple sclerosis (MS). Here, using high-depth RNA sequencing on monocytes, we identified a subset of MS patients with reduced CBX5 expression, correlating with progressive stages of the disease and extensive transcriptomic alterations. Examination of rare non-coding RNA species in these patients revealed impaired maturation/degradation of U snRNAs and enhancer RNAs, indicative of reduced activity of the Integrator, a complex with suspected links to increased MS risk. At protein-coding genes, compromised Integrator activity manifested in reduced pre-mRNA splicing efficiency and altered expression of genes regulated by RNA polymerase II pause-release. Inactivation of Cbx5 in the mouse mirrored most of these transcriptional defects and resulted in hypersensitivity to experimental autoimmune encephalomyelitis. Collectively, our observations suggested a major contribution of the Integrator complex in safeguarding against transcriptional anomalies characteristic of MS, with HP1α/CBX5 emerging as an unexpected regulator of this complex's activity. These findings bring novel insights into the transcriptional aspects of MS and provide potential new criteria for patient stratification.

Insights into the interplay between Epstein-Barr virus (EBV) and multiple sclerosis (MS): A state-of-the-art review and implications for vaccine development

Background and Aims

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS). MS results from an inflammatory process leading to the loss of neural tissue and increased disability over time. The role of Epstein Barr Virus (EBV), as one of the most common global viruses, in MS development has been the subject of several studies. However, many related questions are still unanswered. This study aimed to review the connection between MS and EBV and provide a quick outline of MS prevention using EBV vaccination.

Methods

For this narrative review, an extensive literature search using specific terms was conducted across online databases, including PubMed/Medline, Scopus, Web of Science, and Google Scholar, to identify pertinent studies.

Results

Several studies proved that almost 100% of people with MS showed a history of EBV infection, and there was an association between high titers of EBV antibodies and an increased risk of MS development. Various hypotheses are proposed for how EBV may contribute to MS directly and indirectly: (1) Molecular Mimicry, (2) Mistaken Self, (3) Bystander Damage, and (4) Autoreactive B cells infected with EBV.

Conclusion

Given the infectious nature of EBV and its ability to elude the immune system, EBV emerges as a strong candidate for being the underlying cause of MS. The development of an EBV vaccine holds promise for preventing MS; however, overcoming the challenge of creating a safe and efficacious vaccine presents a significant obstacle.

The association between various viral infections and multiple sclerosis: An umbrella review on systematic review and meta-analysis

Multiple Sclerosis (MS) is one of the immune-mediated demyelinating disorders. Multiple components, including the environment and genetics, are possible factors in the pathogenesis of MS. Also, it can be said that infections are a key component of the host's response to MS development. Finally, we evaluated the relationship between different pathogens and MS disease in this umbrella research. We systematically collected and analysed multiple meta-analyses focused on one particular topic. We utilised the Scopus, PubMed, and Web of Science databases starting with inception until 30 May 2023. The methodological quality of the analysed meta-analysis has been determined based on Assessing the Methodological Quality of Systematic Reviews 2 and Grade, and graph construction and statistical analysis were conducted using Comprehensive Meta-Analysis. The Confidence Interval of effect size was 95% in meta-analyses, and p < 0.05 indicated a statistically meaningful relationship. The included studies evaluated the association between MS and 12 viruses containing SARS-CoV-2, Epstein-Barr virus (EBV), Hepatitis B virus, varicella-zoster virus (VZV), human herpesvirus 6 (HHV-6), HHV-7, HHV-8, HSV-1, HSV-2, Cytomegalovirus, Human Papillomavirus, and influenza. SARS-CoV-2, with a 3.74 odds ratio, has a significantly more potent negative effect on MS among viral infections. After that, EBV, HHV-6, HSV-2, and VZV, respectively, with 3.33, 2.81, 1.76, and 1.72 odds ratios, had a significantly negative relationship with MS (p < 0.05). Although the theoretical evidence mostly indicates that EBV has the greatest effect on MS, recent epidemiological studies have challenged this conclusion and put forward possibilities that SARS-CoV-2 is the culprit. Hence, it was necessary to investigate the effects of SARS-CoV-2 and EBV on MS.

Could Mathematics be the Key to Unlocking the Mysteries of Multiple Sclerosis?

Multiple sclerosis (MS) is an autoimmune, neurodegenerative disease that is driven by immune system-mediated demyelination of nerve axons. While diseases such as cancer, HIV, malaria and even COVID have realised notable benefits from the attention of the mathematical community, MS has received significantly less attention despite the increasing disease incidence rates, lack of curative treatment, and long-term impact on patient well-being. In this review, we highlight existing, MS-specific mathematical research and discuss the outstanding challenges and open problems that remain for mathematicians. We focus on how both non-spatial and spatial deterministic models have been used to successfully further our understanding of T cell responses and treatment in MS. We also review how agent-based models and other stochastic modelling techniques have begun to shed light on the highly stochastic and oscillatory nature of this disease. Reviewing the current mathematical work in MS, alongside the biology specific to MS immunology, it is clear that mathematical research dedicated to understanding immunotherapies in cancer or the immune responses to viral infections could be readily translatable to MS and might hold the key to unlocking some of its mysteries.

The interaction between Epstein-Barr virus and multiple sclerosis genetic risk loci: insights into disease pathogenesis and therapeutic opportunities

Multiple sclerosis (MS) is a chronic neurodegenerative autoimmune disease, characterised by the demyelination of neurons in the central nervous system. Whilst it is unclear what precisely leads to MS, it is believed that genetic predisposition combined with environmental factors plays a pivotal role. It is estimated that close to half the disease risk is determined by genetic factors. However, the risk of developing MS cannot be attributed to genetic factors alone, and environmental factors are likely to play a significant role by themselves or in concert with host genetics. Epstein-Barr virus (EBV) infection is the strongest known environmental risk factor for MS. There has been increasing evidence that leaves little doubt that EBV is necessary, but not sufficient, for developing MS. One plausible explanation is EBV may alter the host immune response in the presence of MS risk alleles and this contributes to the pathogenesis of MS. In this review, we discuss recent findings regarding how EBV infection may contribute to MS pathogenesis via interactions with genetic risk loci and discuss possible therapeutic interventions.

Infections among individuals with multiple sclerosis, Alzheimer's disease and Parkinson's disease

A link between neurodegenerative diseases and infections has been previously reported. However, it is not clear to what extent such link is caused by confounding factors or to what extent it is intimately connected with the underlying conditions. Further, studies on the impact of infections on mortality risk following neurodegenerative diseases are rare. We analysed two data sets with different characteristics: (i) a community-based cohort from the UK Biobank with 2023 patients with multiple sclerosis, 2200 patients with Alzheimer's disease, 3050 patients with Parkinson's disease diagnosed before 1 March 2020 and 5 controls per case who were randomly selected and individually matched to the case; (ii) a Swedish Twin Registry cohort with 230 patients with multiple sclerosis, 885 patients with Alzheimer's disease and 626 patients with Parkinson's disease diagnosed before 31 December 2016 and their disease-free co-twins. The relative risk of infections after a diagnosis of neurodegenerative disease was estimated using stratified Cox models, with adjustment for differences in baseline characteristics. Causal mediation analyses of survival outcomes based on Cox models were performed to assess the impact of infections on mortality. Compared with matched controls or unaffected co-twins, we observed an elevated infection risk after diagnosis of neurodegenerative diseases, with a fully adjusted hazard ratio (95% confidence interval) of 2.45 (2.24-2.69) for multiple sclerosis, 5.06 (4.58-5.59) for Alzheimer's disease and 3.72 (3.44-4.01) for Parkinson's disease in the UK Biobank cohort, and 1.78 (1.21-2.62) for multiple sclerosis, 1.50 (1.19-1.88) for Alzheimer's disease and 2.30 (1.79-2.95) for Parkinson's disease in the twin cohort. Similar risk increases were observed when we analysed infections during the 5 years before diagnosis of the respective disease. Occurrence of infections after diagnosis had, however, relatively little impact on mortality, as mediation of infections on mortality (95% confidence interval) was estimated as 31.89% (26.83-37.11%) for multiple sclerosis, 13.38% (11.49-15.29%) for Alzheimer's disease and 18.85% (16.95-20.97%) for Parkinson's disease in the UK Biobank cohort, whereas it was 6.56% (-3.59 to 16.88%) for multiple sclerosis, -2.21% (-0.21 to 4.65%) for Parkinson's disease and -3.89% (-7.27 to -0.51%) for Alzheimer's disease in the twin cohort. Individuals with studied neurodegenerative diseases display an increased risk of infections independently of genetic and familial environment factors. A similar magnitude of risk increase is present prior to confirmed diagnosis, which may indicate a modulating effect of the studied neurological conditions on immune defences.

Epstein-Barr Virus-Induced Genes and Endogenous Retroviruses in Immortalized B Cells from Patients with Multiple Sclerosis

The immune pathogenesis of multiple sclerosis (MS) is thought to be triggered by environmental factors in individuals with an unfavorable genetic predisposition. Epstein-Barr virus (EBV) infection is a major risk factor for subsequent development of MS. Human endogenous retroviruses (HERVs) can be activated by EBV, and might be a missing link between an initial EBV infection and the later onset of MS. In this study, we investigated differential gene expression patterns in EBV-immortalized lymphoblastoid B cell lines (LCL) from MS-affected individuals (MSLCL) and controls by using RNAseq and qRT-PCR. RNAseq data from LCL mapped to the human genome and a virtual virus metagenome were used to identify possible biomarkers for MS or disease-relevant risk factors, e.g., the relapse rate. We observed that lytic EBNA-1 transcripts seemed to be negatively correlated with age leading to an increased expression in LCL from younger PBMC donors. Further, HERV-K (HML-2) GAG was increased upon EBV-triggered immortalization. Besides the well-known transactivation of HERV-K18, our results suggest that another six HERV loci are up-regulated upon stimulation with EBV. We identified differentially expressed genes in MSLCL, e.g., several HERV-K loci, ERVMER61-1 and ERV3-1, as well as genes associated with relapses. In summary, EBV induces genes and HERV in LCL that might be suitable as biomarkers for MS or the relapse risk.

Antibodies from Multiple Sclerosis Brain Identified Epstein-Barr Virus Nuclear Antigen 1 & 2 Epitopes which Are Recognized by Oligoclonal Bands

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS), the etiology of which is poorly understood. The most common laboratory abnormality associated with MS is increased intrathecal immunoglobulin G (IgG) synthesis and the presence of oligoclonal bands (OCBs) in the brain and cerebrospinal fluid (CSF). However, the major antigenic targets of these antibody responses are unknown. The risk of MS is increased after infectious mononucleosis (IM) due to EBV infection, and MS patients have higher serum titers of anti-EBV antibodies than control populations. Our goal was to identify disease-relevant epitopes of IgG antibodies in MS; to do so, we screened phage-displayed random peptide libraries (12-mer) with total IgG antibodies purified from the brain of a patient with acute MS. We identified and characterized the phage peptides for binding specificity to intrathecal IgG from patients with MS and from controls by ELISA, phage-mediated Immuno-PCR, and isoelectric focusing. We identified two phage peptides that share sequence homologies with EBV nuclear antigens 1 and 2 (EBNA1 and EBNA2), respectively. The specificity of the EBV epitopes found by panning with MS brain IgG was confirmed by ELISA and competitive inhibition assays. Using a highly sensitive phage-mediated immuno-PCR assay, we determined specific bindings of the two EBV epitopes to IgG from CSF from 46 MS and 5 inflammatory control (IC) patients. MS CSF IgG have significantly higher bindings to EBNA1 epitope than to EBNA2 epitope, whereas EBNA1 and EBNA2 did not significantly differ in binding to IC CSF IgG. Further, the EBNA1 epitope was recognized by OCBs from multiple MS CSF as shown in blotting assays with samples separated by isoelectric focusing. The EBNA1 epitope is reactive to MS intrathecal antibodies corresponding to oligoclonal bands. This reinforces the potential role of EBV in the etiology of MS. Graphical abstract Antibodies purified from an MS brain plaque were panned by phage display peptide libraries to discern potential antigens. Phage displaying peptide sequences resembling Epstein-Barr Virus Nuclear Antigens 1 & 2 (EBNA1 & 2) epitopes were identified. Antibodies from sera and CSF from other MS patients also reacted to those epitopes.

Molecular Properties and Therapeutic Targeting of the EBV-Encoded Receptor BILF1

The γ-herpesvirus Epstein-Barr Virus (EBV) establishes lifelong infections in approximately 90% of adults worldwide. Up to 1,000,000 people yearly are estimated to suffer from health conditions attributed to the infection with this virus, such as nasopharyngeal and gastric carcinomas as well as several forms of B, T and NK cell lymphoma. To date, no EBV-specific therapeutic option has reached the market, greatly reducing the survival prognoses of affected patients. Similar to other herpesviruses, EBV encodes for a G protein-coupled receptor (GPCR), BILF1, affecting a multitude of cellular signaling pathways. BILF1 has been identified to promote immune evasion and tumorigenesis, effectively ensuring a life-long persistence of EBV in, and driving detrimental health conditions to its host. This review summarizes the epidemiology of EBV-associated malignancies, their current standard-of-care, EBV-specific therapeutics in development, GPCRs and their druggability, and most importantly consolidates the findings of over 15 years of research on BILF1 in the context of EBV-specific drug development. Taken together, BILF1 constitutes a promising target for the development of novel EBV-specific therapeutics.

Infections and multiple sclerosis: Recommendations from the French Multiple Sclerosis Society

INTRODUCTION

Viral, bacterial, or fungal infections are suspected of triggering multiple sclerosis (MS) and promoting relapses of the disease and are likely to be promoted by immune-active treatments. This raises questions about the infectious workup and preventive treatment of these infections prior to their initiation.

OBJECTIVES

To establish recommendations on infections and MS. Provide information to patients and healthcare professionals on the minimal infectious workup to be performed in an MS patient at diagnosis and prior to initiation of immuno-active therapy in MS.

METHODS

The recommendation attempts to answer four main questions about infections and MS. The French Group for Recommendations in Multiple Sclerosis (France4MS) did a systematic review of articles from PubMed and universities databases (from January 1975 to June 2020), using the RAND/UCLA formalized consensus method. The RAND/UCLA method has been developed to synthesize the scientific literature and expert opinions on health care topics and was used for reaching a formal agreement. Twenty-three experts contributed to the detailed review and a group of 63 multidisciplinary health professionals validated the final version of 36 recommendations.

RESULTS

It is recommended that MS patients undergo a minimal infectious workup, check their vaccination status at diagnosis, and repeat it during follow-up and before starting immunotherapy. Screening and preventive treatment of viral (group Herpes virus, HPV, JCV, HCV, HBV), bacterial (mycobacteria) and fungal (Cryptococcus) infections is recommended prior to the initiation of certain immuno-active MS therapies.

DISCUSSION AND CONCLUSIONS

At diagnosis of MS and prior to the choice of therapeutic strategy, it is recommended to update the vaccination schedule of MS patients in reference to the HCSP vaccination schedule and the SFSEP recommendations. Before starting immunosuppressive treatment, it is recommended to inform patients of the risks of infections and to look for a constitutive or acquired immune deficiency. Health professionals and patients should be informed of the updated recommendations on infections and MS.

The CD8 T Cell-Epstein-Barr Virus-B Cell Trialogue: A Central Issue in Multiple Sclerosis Pathogenesis

The cause and the pathogenic mechanisms leading to multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system (CNS), are still under scrutiny. During the last decade, awareness has increased that multiple genetic and environmental factors act in concert to modulate MS risk. Likewise, the landscape of cells of the adaptive immune system that are believed to play a role in MS immunopathogenesis has expanded by including not only CD4 T helper cells but also cytotoxic CD8 T cells and B cells. Once the key cellular players are identified, the main challenge is to define precisely how they act and interact to induce neuroinflammation and the neurodegenerative cascade in MS. CD8 T cells have been implicated in MS pathogenesis since the 80's when it was shown that CD8 T cells predominate in MS brain lesions. Interest in the role of CD8 T cells in MS was revived in 2000 and the years thereafter by studies showing that CNS-recruited CD8 T cells are clonally expanded and have a memory effector phenotype indicating in situ antigen-driven reactivation. The association of certain MHC class I alleles with MS genetic risk implicates CD8 T cells in disease pathogenesis. Moreover, experimental studies have highlighted the detrimental effects of CD8 T cell activation on neural cells. While the antigens responsible for T cell recruitment and activation in the CNS remain elusive, the high efficacy of B-cell depleting drugs in MS and a growing number of studies implicate B cells and Epstein-Barr virus (EBV), a B-lymphotropic herpesvirus that is strongly associated with MS, in the activation of pathogenic T cells. This article reviews the results of human studies that have contributed to elucidate the role of CD8 T cells in MS immunopathogenesis, and discusses them in light of current understanding of autoreactivity, B-cell and EBV involvement in MS, and mechanism of action of different MS treatments. Based on the available evidences, an immunopathological model of MS is proposed that entails a persistent EBV infection of CNS-infiltrating B cells as the target of a dysregulated cytotoxic CD8 T cell response causing CNS tissue damage.

Regulation of the expression of human endogenous retroviruses: elements in fetal development and a possible role in the development of cancer and neurological diseases

Human endogenous retroviruses (HERVs) are remnants of ancient retroviral germline infections. Most HERV sequences are silenced in somatic cells, but interest is emerging on the involvement of HERV derived transcripts and proteins in human physiology and disease. A HERV-W encoded protein, syncytin-1, has been co-opted into fetal physiology, where it plays a role in trophoblast formation. Altered HERV transcription and expression of HERV derived proteins are associated with various cancer types and neurological diseases such as multiple sclerosis (MS). The implication of HERVs as potential mediators of both health and disease suggests important roles of regulatory mechanisms and alterations of these in physiological and pathological processes. The regulation of HERV sequences is mediated by a wide variety of mechanisms, and the focus of this review is on selected aspects of these, including epigenetic mechanisms such as CpG methylation and histone modifications of the HP1-H3K9me axis, viral transactivation events, and regulatory perspectives of transient stimuli in the microenvironment. Increasing knowledge of the regulation of HERV sequences will not only contribute to the understanding of complex pathogeneses, but also may pinpoint potential targets for better diagnosis and treatment in complex diseases as MS.

The role of Epstein-Barr virus in the etiology of multiple sclerosis: a current review

Introduction: Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. While its exact etiology is unknown, it is generally believed that MS is caused by environmental triggers in genetically predisposed individuals. Strong and consistent evidence suggests a key role of Epstein-Barr virus (EBV), a B lymphotropic human gammaherpesvirus, in the etiology of MS. Areas covered: This review summarizes recent developments in the field of EBV and MS with a focus on potential mechanisms underlying the role of EBV in MS. PubMed was searched for the terms 'Epstein-Barr virus' and 'multiple sclerosis'. Expert opinion: The current evidence is compatible with the working hypothesis that MS is a rare complication of EBV infection. Under the premise of a causative role of EBV in MS, it needs to be postulated that EBV causes a specific, and likely persistent, change(s) that is necessarily required for the development of MS. However, although progress has been made, the nature of that change and thus the precise mechanism explaining the role of EBV in MS remain elusive. The mechanism of EBV in MS therefore is a pressing question, whose clarification may substantially advance the pathophysiological understanding, rational therapies, and prevention of MS.

Recent advances in understanding multiple sclerosis

Emerging data point to important contributions of both autoimmune inflammation and progressive degeneration in the pathophysiology of multiple sclerosis (MS). Unfortunately, after decades of intensive investigation, the fundamental cause remains unknown. A large body of research on the immunobiology of MS has resulted in a variety of anti-inflammatory therapies that are highly effective at reducing brain inflammation and clinical/radiological relapses. However, despite potent suppression of inflammation, benefit in the more important and disabling progressive phase is extremely limited; thus, progressive MS has emerged as the greatest challenge for the MS research and clinical communities. Data obtained over the years point to a complex interplay between environment (e.g., the near-absolute requirement of Epstein-Barr virus exposure), immunogenetics (strong associations with a large number of immune genes), and an ever more convincing role of an underlying degenerative process resulting in demyelination (in both white and grey matter regions), axonal and neuro-synaptic injury, and a persistent innate inflammatory response with a seemingly diminishing role of T cell-mediated autoimmunity as the disease progresses. Together, these observations point toward a primary degenerative process, one whose cause remains unknown but one that entrains a nearly ubiquitous secondary autoimmune response, as a likely sequence of events underpinning this disease. Here, we briefly review what is known about the potential pathophysiological mechanisms, focus on progressive MS, and discuss the two main hypotheses of MS pathogenesis that are the topic of vigorous debate in the field: whether primary autoimmunity or degeneration lies at the foundation. Unravelling this controversy will be critically important for developing effective new therapies for the most disabling later phases of this disease.

Differential serostatus of Epstein-Barr virus in Iranian MS patients with various clinical patterns

Background: Epidemiological evidence suggests a role of Epstein-Barr virus (EBV) in triggering the pathogenesis of Multiple Sclerosis (MS). The aim of this study was to assess the EBV-specific antibodies in MS patients with various clinical patterns and their association with the production of IFN-γ, IL-12, and IL-4 cytokines compared with healthy individuals.

Methods: We measured EBNA-1 IgG, VCA IgG, and production of IFN-γ, IL-12 and IL-4 cytokines in patients with different clinical patterns and healthy controls using ELISA method.

Results: There was a higher titer of anti-EBV antibodies in MS patients compared to healthy controls. SPMS patients generated higher EBNA-1 levels than those with RRMS and PPMS patients whereas; the level of VCA IgG was higher in the RRMS patients than PPMS. In PPMS patients, a significant increase was found in IFN-γ and IL-12 cytokines compared to other subtypes, whereas IL-4 cytokine had a decreased level compared to RRMS patients. Higher anti-EBV antibodies are associated with increased IL-12 cytokine in RRMS patients. However, no significant correlation was found between these antibodies and other secreted cytokines.

Conclusion: EBV infection is one of the strong risk factors for MS. Acting on these factors could be useful to decrease the incidence and disease exacerbation of MS. Study of the antibody levels to EBV virus could be useful for evaluating MS risk score in each clinical subtypes.

Primary Progressive Multiple Sclerosis: Putting Together the Puzzle

The focus of multiple sclerosis research has recently turned to the relatively rare and clearly more challenging condition of primary progressive multiple sclerosis (PPMS). Many risk factors such as genetic susceptibility, age, and Epstein–Barr virus (EBV) infection may interdepend on various levels, causing a complex pathophysiological cascade. Variable pathological mechanisms drive disease progression, including inflammation-associated axonal loss, continuous activation of central nervous system resident cells, such as astrocytes and microglia as well as mitochondrial dysfunction and iron accumulation. Histological studies revealed diffuse infiltration of the gray and white matter as well as of the meninges with inflammatory cells such as B-, T-, natural killer, and plasma cells. While numerous anti-inflammatory agents effective in relapsing remitting multiple sclerosis basically failed in treatment of PPMS, the B-cell-depleting monoclonal antibody ocrelizumab recently broke the dogma that PPMS cannot be treated by an anti-inflammatory approach by demonstrating efficacy in a phase 3 PPMS trial. Other treatments aiming at enhancing remyelination (MD1003) as well as EBV-directed treatment strategies may be promising agents on the horizon. In this article, we aim to summarize new advances in the understanding of risk factors, pathophysiology, and treatment of PPMS. Moreover, we introduce a novel concept to understand the nature of the disease and possible treatment strategies in the near future.

Papel de las enfermedades infecciosas en el desarrollo de la esclerosis múltiple: evidencia científica

Introducción

La esclerosis múltiple (EM) es el trastorno inflamatorio más común del sistema nervioso central (SNC) y la causa principal de discapacidad neurológica en adultos jóvenes. Los factores ambientales e infecciosos han sido fuertemente asociados al incremento de la ocurrencia de la enfermedad, hasta más del doble, en los últimos 10 años. En este artículo de revisión se describen los principales hallazgos reportados sobre la relación entre ciertas infecciones virales y bacterianas con la aparición y progresión de la EM.

Métodos

Se realizó un plan metodológico de búsqueda de artículos científicos relacionados con infección y EM, mediante la búsqueda de artículos científicos, principalmente publicados en inglés, en las plataformas virtuales de Pubmed, Medline y Cochrane. Para la búsqueda se utilizaron como palabras claves (términos MeSH): «virus, bacteria, autoimmune disease of the nervous system, multiple sclerosis». Se eligieron artículos publicados en revistas indexadas durante los últimos 15 años.

Resultados

Estudios epidemiológicos sugieren que la EM tiene un componente etiológico infeccioso que origina un proceso inflamatorio que puede contribuir a la iniciación o exacerbación de la enfermedad. Particularmente, la infección viral y los eventos de desmielinización en el SNC puede deberse a la penetración de un virus como el virus Epstein-Barr (EBV), a través del torrente sanguíneo, específicamente hacia el SNC. Por otro lado, las infecciones bacterianas crónicas pueden causar procesos de desmielinización en el SNC que agravan la enfermedad de EM.

Conclusiones

Este estudio contribuye a aportar evidencia científica donde se demuestra la multicausalidad implicada en la ocurrencia de la EM. Aún falta desarrollar más estudios epidemiológicos que demuestren y comprueben la relación y la implicación de agentes virales y bacterianos en el origen, el desarrollo y la severidad de la enfermedad.

EBV Infection and Multiple Sclerosis: Lessons from a Marmoset Model

Multiple sclerosis (MS) is thought to be initiated by the interaction of genetic and environmental factors, eliciting an autoimmune attack on the central nervous system. Epstein-Barr virus (EBV) is the strongest infectious risk factor, but an explanation for the paradox between high infection prevalence and low MS incidence remains elusive. We discuss new data using marmosets with experimental autoimmune encephalomyelitis (EAE) - a valid primate model of MS. The findings may help to explain how a common infection can contribute to the pathogenesis of MS. We propose that EBV infection induces citrullination of peptides in conjunction with autophagy during antigen processing, endowing B cells with the capacity to cross-present autoantigen to CD8⁺CD56⁺ T cells, thereby leading to MS progression.

Cancer co-occurrence patterns in Parkinson's disease and multiple sclerosis-Do they mirror immune system imbalances?

BACKGROUND

To examine the site-specific cancer mortality among deaths registered with Parkinson's disease (PD) and multiple sclerosis (MS). We focused on the patterns related to the most frequent cancers.

METHODS

We analyzed Swiss mortality data over a 39-year period (1969-2007), using a statistical approach applicable to unique daabases, i.e. when no linkage with morbidity databases or disease registries is possible. It was based on a case-control design with bootstrapping to derive standardized mortality ratios (SMR). The cases were defined by the cancer-PD or cancer-MS co-registrations, whereas the controls were drawn from the remaining records with cancer deaths (matching criteria: sex, age, language region of Switzerland, subperiods 1969-1981, 1982-1994, 1995-2007).

RESULTS

For PD we found lower SMRs in lung and liver cancer and higher SMRs in melanoma/skin cancer, and in cancers of breast and prostate. As for MS, the SMR in lung cancer was lower than expected, whereas SMRs in colorectal, breast and bladder cancer were higher.

CONCLUSIONS

A common pattern of associations can be observed in PD and MS, with a lower risk of lung cancer and higher risk of breast cancer than expected. Thus, PD and MS resemble other conditions with similar (schizophrenia) or reversed patterns (rheumatoid arthritis, immunosuppression after organ transplantation).

Epstein-Barr virus in multiple sclerosis

BACKGROUND/OBJECTIVES

Multiple sclerosis (MS) is an inflammatory disorder of the central nervous system. Many diseases are associated with Epstein-Barr virus (EBV) infection, such as infectious mononucleosis and many types of malignancies, and it is thought to be related to some diseases of autoimmune origin, such as rheumatoid arthritis, systemic lupus erythematosis, and others. The present study aimed to assess EBV in patients with MS.

PATIENTS AND METHODS

This case-control study was conducted from October 2012 to September 2013 on 75 MS patients and non-MS controls. Both were tested quantitatively for immunoglobulin G (IgG) antibodies against Epstein-Barr nuclear antigen-1 (EBNA1) and viral capsid antigen (VCA) using the enzyme linked immunosorbent assay technique.

RESULTS

Seventy MS patients (93.3%) were positive for EBNA1 IgG compared with 68 controls (90.7%). In MS patients, the mean EBNA1 IgG serum level was 310.91 (±131.05) U/ml; meanwhile, among controls the mean serum EBNA IgG level was 177.81 (±104.98) U/ml.All patients with MS were positive for VCA IgG, whereas only 60 (80.0%) controls were positive. In the MS group, the VCA IgG mean level was 302.19 (±152.11) U/ml compared with 167.94 (±111.79) U/ml in controls. The differences in the serum levels of both markers between the two groups were statistically significant (P<0.001).

CONCLUSION AND RECOMMENDATIONS

EBV proved to have a unique immunological pattern in MS patients when compared with non-MS controls. Further studies for more confirmation of the relation between EBV and MS on a large scale are recommended.

Identifying Patient-Specific Epstein-Barr Nuclear Antigen-1 Genetic Variation and Potential Autoreactive Targets Relevant to Multiple Sclerosis Pathogenesis

Background

Epstein-Barr virus (EBV) infection represents a major environmental risk factor for multiple sclerosis (MS), with evidence of selective expansion of Epstein-Barr Nuclear Antigen-1 (EBNA1)-specific CD4+ T cells that cross-recognize MS-associated myelin antigens in MS patients. HLA-DRB1*15-restricted antigen presentation also appears to determine susceptibility given its role as a dominant risk allele. In this study, we have utilised standard and next-generation sequencing techniques to investigate EBNA-1 sequence variation and its relationship to HLA-DR15 binding affinity, as well as examining potential cross-reactive immune targets within the central nervous system proteome.

Methods

Sanger sequencing was performed on DNA isolated from peripheral blood samples from 73 Western Australian MS cases, without requirement for primary culture, with additional FLX 454 Roche sequencing in 23 samples to identify low-frequency variants. Patient-derived viral sequences were used to predict HLA-DRB1*1501 epitopes (NetMHCII, NetMHCIIpan) and candidates were evaluated for cross recognition with human brain proteins.

Results

EBNA-1 sequence variation was limited, with no evidence of multiple viral strains and only low levels of variation identified by FLX technology (8.3% nucleotide positions at a 1% cut-off). In silico epitope mapping revealed two known HLA-DRB1*1501-restricted epitopes (‘AEG’: aa 481–496 and ‘MVF’: aa 562–577), and two putative epitopes between positions 502–543. We identified potential cross-reactive targets involving a number of major myelin antigens including experimentally confirmed HLA-DRB1*15-restricted epitopes as well as novel candidate antigens within myelin and paranodal assembly proteins that may be relevant to MS pathogenesis.

Conclusions

This study demonstrates the feasibility of obtaining autologous EBNA-1 sequences directly from buffy coat samples, and confirms divergence of these sequences from standard laboratory strains. This approach has identified a number of immunogenic regions of EBNA-1 as well as known and novel targets for autoreactive HLA-DRB1*15-restricted T cells within the central nervous system that could arise as a result of cross-reactivity with EBNA-1-specific immune responses.

Age- and gender-specific effects on VDR gene polymorphisms and risk of the development of multiple sclerosis in Tunisians: a preliminary study

The vitamin D receptor (VDR) polymorphisms have been reported to be associated with multiple sclerosis (MS); however, evidence remains conflicting. In this report, we investigated the association between two single nucleotide polymorphisms (SNPs) TaqI and ApaI of VDR gene and risk development of MS. TaqI and ApaI SNPs were detected by PCR-RFLP from the DNA of 60 Tunisian patients with MS and 114 healthy controls. Our results show a significant difference of the allelic frequency distribution between the case and control groups for TaqI SNP (P = 0.01), but genotype frequencies were not significantly different (P = 0.07 and 0.23). When adjusting frequency distribution of different alleles and genotypes by age, we found that the difference between the T allele frequencies of this SNP in the group of patients age [15-24] in comparison with the control group of the same age group was statistically significant (P = 0.026). Moreover, frequency of the T allele was significantly higher in male patients compared with controls of the same sex (P = 0.017). However, neither the genotype nor the allele frequency distribution was significantly different between the MS and control populations for the ApaI SNP. Our preliminary results indicate that VDR gene polymorphism could be associated with susceptibility to MS. The role of VDR gene polymorphism should be further studied in other large populations, and the distribution of other polymorphism, such as FokI and BsmI, should be also analysed to confirm another susceptibility polymorphisms gene for MS and to obtain more adequate strategies for treatment of MS.

Targeting Epstein-Barr virus infection as an intervention against multiple sclerosis

We here review contemporary data on genetic and environmental risk factors, particularly Epstein-Barr virus infection, for multiple sclerosis. There is an important immunogenetic etiological factor for multiple sclerosis. However, a general assumption is that immune defense genes are activated by the environment, basically by infections. We contend that the relationship between infectious mononucleosis and multiple sclerosis cannot be completely explained by genetics and inverse causality. Epstein-Barr infection as indicated by positive serology is an obligatory precondition for multiple sclerosis, which is a stronger attribute than a risk factor only. Data on events in the early pathogenesis of multiple sclerosis are cumulating from bio-banks with presymptomatic specimens, but there is only little information from the critical age when Epstein-Barr infection including infectious mononucleosis is acquired, nor on the detailed immunological consequences of this infection in individuals with and without multiple sclerosis. We discuss how focused bio-banking may elaborate a rationale for the development of treatment or vaccination against Epstein-Barr virus infection. A cohort in which intervention against Epstein-Barr infections was performed should be the object of neurological follow-up.

IFN-β and multiple sclerosis: from etiology to therapy and back

Several immunomodulatory treatments are currently available for relapsing-remitting forms of multiple sclerosis (RRMS). Interferon beta (IFN) was the first therapeutic intervention able to modify the course of the disease and it is still the most used first-line treatment in RRMS. Though two decades have passed since IFN-β was introduced in the management of MS, it remains a valid approach because of its good benefit/risk profile. This is witnessed by new efforts of pharmaceutical industry to improve this line: a PEGylated form of subcutaneous IFN-β 1a, (Plegridy(®)) with a longer half-life, has been recently approved in RRMS. This review will survey the various stages of the use of type I IFN in MS, with special attention to the effect of the treatment on the supposed viral etiologic factors associated to the disease. The antiviral activities of IFN (that initially prompted its use as immunomodulatory agent in MS), and the mounting evidences in favor of a viral etiology in MS, allowed us to outline a re-appraisal from etiology to therapy and back.

Epstein-Barr virus and multiple sclerosis: potential opportunities for immunotherapy

Multiple sclerosis (MS) is a common chronic inflammatory demyelinating disease of the central nervous system (CNS) causing progressive disability. Many observations implicate Epstein–Barr virus (EBV) in the pathogenesis of MS, namely universal EBV seropositivity, high anti-EBV antibody levels, alterations in EBV-specific CD8⁺ T-cell immunity, increased spontaneous EBV-induced transformation of peripheral blood B cells, increased shedding of EBV from saliva and accumulation of EBV-infected B cells and plasma cells in the brain. Several mechanisms have been postulated to explain the role of EBV in the development of MS including cross-reactivity between EBV and CNS antigens, bystander damage to the CNS by EBV-specific CD8⁺ T cells, activation of innate immunity by EBV-encoded small RNA molecules in the CNS, expression of αB-crystallin in EBV-infected B cells leading to a CD4⁺ T-cell response against oligodendrocyte-derived αB-crystallin and EBV infection of autoreactive B cells, which produce pathogenic autoantibodies and provide costimulatory survival signals to autoreactive T cells in the CNS. The rapidly accumulating evidence for a pathogenic role of EBV in MS provides ground for optimism that it might be possible to prevent and cure MS by effectively controlling EBV infection through vaccination, antiviral drugs or treatment with EBV-specific cytotoxic CD8⁺ T cells. Adoptive immunotherapy with in vitro-expanded autologous EBV-specific CD8⁺ T cells directed against viral latent proteins was recently used to treat a patient with secondary progressive MS. Following the therapy, there was clinical improvement, decreased disease activity on magnetic resonance imaging and reduced intrathecal immunoglobulin production.

Role of pathogens in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating autoimmune disease of the central nervous system (CNS). Although the etiology of MS is unknown, genetic and environmental factors play a role. Infectious pathogens are the likely environmental factors involved in the development of MS. Pathogens associated with the development or exacerbation of MS include bacteria, such as Mycoplasma pneumoniae and Chlamydia pneumoniae, the Staphylococcus aureus-produced enterotoxins that function as superantigens, viruses of the herpes virus (Epstein-Barr virus and human herpesvirus 6) and human endogenous retrovirus (HERV) families and the protozoa Acanthamoeba castellanii. Evidence, from studies with humans and animal models, supporting the association of these various pathogens with the development and/or exacerbation of MS will be discussed along with the potential mechanisms including molecular mimicry, epitope spreading and bystander activation. In contrast, infection with certain parasites such as helminthes (Schistosoma mansoni, Fasciola hepatica, Hymenolepis nana, Trichuris trichiura, Ascaris lumbricoides, Strongyloides stercolaris, Enterobius vermicularis) appears to protect against the development or exacerbation of MS. Evidence supporting the ability of parasitic infections to protect against disease will be discussed along with a brief summary of a recent Phase I clinical trial testing the ability of Trichuris suis ova treatment to improve the clinical course of MS. A complex interaction between the CNS (including the blood-brain barrier), multiple infections with various infectious agents (occurring in the periphery or within the CNS), and the immune response to those various infections may have to be deciphered before the etiology of MS can be fully understood.

Is a hypothetical melanoma-like neuromelanin the underlying factor essential for the aetiopathogenesis and clinical manifestations of multiple sclerosis?

Background

Multiple sclerosis (MS) has undergone a significant increase in incidence in the industrialised nations over the last 130 years. Changing environmental factors, possibly infections or a lack of or altered timing of them, determine the prevalence of the disease. Although a plethora of aetiological factors, clearly evident in a group of children with MS, appear relevant, there may nevertheless be a single factor essential for the aetiopathogenesis and clinical manifestation of MS.

Description and discussion

This hitherto unknown factor is postulated to be a ‘melanoma-like neuromelanin’ (MLN) dependent on the activation of a gene for syncytin-1. An involvement of MLN could explain the diverse findings in the epidemiology, immunology and pathology of MS, requiring a consideration of a complex infectious background, the human leucocyte antigens, as well as cosmic radiation causing geomagnetic disturbances, vitamin D deficiency, smoking, and lower levels of uric acid.

Summary

In principle, the MLN-based concept is a unifying one, capable of explaining a number of characteristics of the disease. To date, MLN has not been addressed in studies on MS and future work will need to be done on human patients, as there is little or no neuromelanin (the precursor of MLN) in the animals used as experimental models in the study of MS.

Glatiramer acetate in treatment of multiple sclerosis: a toolbox of random co-polymers for targeting inflammatory mechanisms of both the innate and adaptive immune system?

Multiple sclerosis is a disease of the central nervous system, resulting in the demyelination of neurons, causing mild to severe symptoms. Several anti-inflammatory treatments now play a significant role in ameliorating the disease. Glatiramer acetate (GA) is a formulation of random polypeptide copolymers for the treatment of relapsing-remitting MS by limiting the frequency of attacks. While evidence suggests the influence of GA on inflammatory responses, the targeted molecular mechanisms remain poorly understood. Here, we review the multiple pharmacological modes-of-actions of glatiramer acetate in treatment of multiple sclerosis. We discuss in particular a newly discovered interaction between the leukocyte-expressed integrin α(M)β(2) (also called Mac-1, complement receptor 3, or CD11b/CD18) and perspectives on the GA co-polymers as an influence on the function of the innate immune system.

Epstein-Barr virus peptide presented by HLA-E is predominantly recognized by CD8(bright) cells in multiple sclerosis patients

Multiple sclerosis (MS) is associated with Epstein-Barr virus (EBV) infection, but impaired immune suppression may be part of the disease pathogenesis. CD8(+) T cells that are restricted by HLA-E exert an important immunoregulatory mechanism. To explore how EBV might interfere with immune regulation, we examined the expression of HLA-E and the frequency of CD8(+) cells recognizing HLA-E, presenting either an EBV peptide from the BZLF1 protein or a signal sequence peptide from HLA-A2, in relapsing remitting (MS-RR), primary progressive (MS-PP) MS patients, and healthy controls (HC). Treatment with IFN-α or EBV increased HLA-E expression on CD4(+) cells. However, only MS-PP had increased expression of HLA-E on resting CD4(+) cells when compared with HC (p<0.005). CD8(+) cells were divided into CD8(bright) and CD8(dim) cells by flow cytometry analyses. MS-RR had significantly fewer CD8(dim) cells than HC (p<0.003). Flow cytometry analyses were performed with HLA-E tetramers folded in the presence of the EBV or HLA-A2 peptide to identify HLA-E-interacting cells. MS-RR had increased frequency of CD8(bright) cells recognizing HLA-E/A2 (p=0.006) and HLA-E/BZLF1 (p=0.016). Conversely, MS-RR had fewer CD8(dim) cells that recognized HLA-E/BZLF1 (p=0.001), but this could be attributed to the overall lower number of CD8(dim) cells in MS-RR. Whereas HLA-E/A2 was predominantly recognized by CD8(dim) cells, HLA-E/BZLF1 was predominantly recognized by CD8(bright) cells in MS-RR and MS-PP, but not in HC. As expected, HLA-E/A2 was also recognized by CD8-negative cells in a CD94-dependent manner, whereas HLA-E/BZLF1 was poorly recognized in all groups by CD8-negative cells. These data demonstrate that MS-RR patients have expanded their CD8(bright) cells recognizing HLA-E/BZLF1. Moreover, HLA-E/BZLF1 appears to be recognized by the immune system in a different manner than HLA-E/A2.

Association between interleukin-10 gene polymorphisms and susceptibility to irritable bowel syndrome: A meta-analysis

AIM: To investigate the association between interleukin-10 (IL-10) gene polymorphisms and genetic susceptibility to irritable bowel syndrome (IBS).

METHODS: Published work involving IBS from PubMed, EMBASE, Cochrane library in English and from China Academic Journal, Chinese BioMedical Literature Database, Wanfang Database in Chinese were searched for relevant articles. Correlation analysis was performed using RevMan 5.0.

RESULTS: Seven studies were finally accepted for analysis. There were four studies focused on IL-10-592 polymorphism, four studies on IL-10-819 polymorphism, and seven studies on IL-10-1082 polymorphism. The odds ratio (OR) was 1.26 (95% CI: 1.03-1.54, P = 0.02) for the -592 A allele, 1.67 (95% CI: 0.71-3.93, P = 0.24) for -592 AA genotype, 1.24 (95% CI: 1.02-1.52, P = 0.03) for the -819 T allele, 1.31 (95% CI: 0.59-2.91, P = 0.50) for -819 TT genotype, 1.00 (95% CI: 0.86-1.17, P = 0.98) for the -1082 G allele, and 0.68 (95% CI: 0.51-0.92, P = 0.01) for -1082 GG genotype. Subgroup analysis showed that the OR of -1082 GG was 0.71 (95% CI: 0.52-0.97, P = 0.03) in Western population, and 0.42 (95% CI: 0.13-1.31, P = 0.13) in the Eastern population.

CONCLUSION: Our meta-analysis suggests that the -1082 GG genotype is a risk factor for IBS in Western people, and the -592 A allele and -819 T allele might be risk factors for IBS in Eastern people.

Epstein-Barr virus and systemic lupus erythematosus

The etiology of SLE is not fully established. SLE is a disease with periods of waning disease activity and intermittent flares. This fits well in theory to a latent virus infection, which occasionally switches to lytic cycle, and EBV infection has for long been suspected to be involved. This paper reviews EBV immunobiology and how this is related to SLE pathogenesis by illustrating uncontrolled reactivation of EBV as a disease mechanism for SLE. Studies on EBV in SLE patients show enlarged viral load, abnormal expression of viral lytic genes, impaired EBV-specific T-cell response, and increased levels of EBV-directed antibodies. These results suggest a role for reactivation of EBV infection in SLE. The increased level of EBV antibodies especially comprises an elevated titre of IgA antibodies, and the total number of EBV-reacting antibody isotypes is also enlarged. As EBV is known to be controlled by cell-mediated immunity, the reduced EBV-specific T-cell response in SLE patients may result in defective control of EBV causing frequent reactivation and expression of lytic cycle antigens. This gives rise to enhanced apoptosis and amplified cellular waste load resulting in activation of an immune response and development of EBV-directed antibodies and autoantibodies to cellular antigens.

Autoimmunity, dendritic cells and relevance for Parkinson's disease

Innate and adaptive immune responses in neurodegenerative diseases have become recently a focus of research and discussions. Parkinson’s disease (PD) is a neurodegenerative disorder without known etiopathogenesis. The past decade has generated evidence for an involvement of the immune system in PD pathogenesis. Both inflammatory and autoimmune mechanisms have been recognized and studies have emphasized the role of activated microglia and T-cell infiltration. In this short review, we focus on dendritic cells, on their role in initiation of autoimmune responses, we discuss aspects of neuroinflammation and autoimmunity in PD, and we report new evidence for the involvement of neuromelanin in these processes.

Multiple sclerosis-linked and interferon-beta-regulated gene expression in plasmacytoid dendritic cells

The cause of multiple sclerosis (MS) is not known and the mechanism of interferon-beta, a disease-modifying treatment, is not well-understood. We studied gene expression in plasmacytoid dendritic cells (pDCs), antigen-presenting cells implicated in MS pathogenesis. PDCs were separated from healthy donors and MS patients at two time points: before and after initiation of treatment with interferon-beta. Expression of selected MS-linked and interferon-beta-regulated genes was validated with single assays. We have identified 60 genes which were abnormally expressed in MS patients and were corrected after treatment. These genes could be studied as potential MS biomarkers and possible therapeutic targets in MS.

Epstein-barr virus as a trigger of autoimmune liver diseases

The pathogenesis of autoimmune diseases includes a combination of genetic factors and environmental exposures including infectious agents. Infectious triggers are commonly indicated as being involved in the induction of autoimmune disease, with Epstein-Barr virus (EBV) being implicated in several autoimmune disorders. EBV is appealing in the pathogenesis of autoimmune disease, due to its high prevalence worldwide, its persistency throughout life in the host's B lymphocytes, and its ability to alter the host's immune response and to inhibit apoptosis. However, the evidence in support of EBV in the pathogenesis varies among diseases. Autoimmune liver diseases (AiLDs), including autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC), have a potential causative link with EBV. The data surrounding EBV and AiLD are scarce. The lack of evidence surrounding EBV in AiLD may also be reflective of the rarity of these conditions. EBV infection has also been linked to other autoimmune conditions, which are often found to be concomitant with AiLD. This paper will critically examine the literature surrounding the link between EBV infection and AiLD development. The current evidence is far from being conclusive of the theory of a link between EBV and AiLD.

CD8+ T-Cell Deficiency, Epstein-Barr Virus Infection, Vitamin D Deficiency, and Steps to Autoimmunity: A Unifying Hypothesis

CD8+ T-cell deficiency is a feature of many chronic autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, dermatomyositis, primary biliary cirrhosis, primary sclerosing cholangitis, ulcerative colitis, Crohn's disease, psoriasis, vitiligo, bullous pemphigoid, alopecia areata, idiopathic dilated cardiomyopathy, type 1 diabetes mellitus, Graves' disease, Hashimoto's thyroiditis, myasthenia gravis, IgA nephropathy, membranous nephropathy, and pernicious anaemia. It also occurs in healthy blood relatives of patients with autoimmune diseases, suggesting it is genetically determined. Here it is proposed that this CD8+ T-cell deficiency underlies the development of chronic autoimmune diseases by impairing CD8+ T-cell control of Epstein-Barr virus (EBV) infection, with the result that EBV-infected autoreactive B cells accumulate in the target organ where they produce pathogenic autoantibodies and provide costimulatory survival signals to autoreactive T cells which would otherwise die in the target organ by activation-induced apoptosis. Autoimmunity is postulated to evolve in the following steps: (1) CD8+ T-cell deficiency, (2) primary EBV infection, (3) decreased CD8+ T-cell control of EBV, (4) increased EBV load and increased anti-EBV antibodies, (5) EBV infection in the target organ, (6) clonal expansion of EBV-infected autoreactive B cells in the target organ, (7) infiltration of autoreactive T cells into the target organ, and (8) development of ectopic lymphoid follicles in the target organ. It is also proposed that deprivation of sunlight and vitamin D at higher latitudes facilitates the development of autoimmune diseases by aggravating the CD8+ T-cell deficiency and thereby further impairing control of EBV. The hypothesis makes predictions which can be tested, including the prevention and successful treatment of chronic autoimmune diseases by controlling EBV infection.

Epigenetic dysregulation of epstein-barr virus latency and development of autoimmune disease

Epstein-Barr virus (EBV) is ahumanherpesvirus thatpersists in the memory B-cells of the majority of the world population in a latent form. Primary EBV infection is asymptomatic or causes a self-limiting disease, infectious mononucleosis. Virus latency is associated with a wide variety of neoplasms whereof some occur in immune suppressed individuals. Virus production does not occur in strict latency. The expression of latent viral oncoproteins and nontranslated RNAs is under epigenetic control via DNA methylation and histone modifications that results either in a complete silencing of the EBV genome in memory B cells, or in a cell-type dependent usage of a couple of latency promoters in tumor cells, germinal center B cells and lymphoblastoid cells (LCL, transformed by EBV in vitro). Both, latent and lytic EBV proteins elicit a strong immune response. In immune suppressed and infectious mononucleosis patients, an increased viral load can be detected in the blood. Enhanced lytic replication may result in new infection- and transformation-events and thus is a risk factor both for malignant transformation and the development of autoimmune diseases. An increased viral load or a changed presentation of a subset of lytic or latent EBV proteins that cross-react with cellular antigens may trigger pathogenic processes through molecular mimicry that result in multiple sclerosis (MS), systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).

Recognition of herpesviruses by the innate immune system

Advances in innate immunity over the past decade have revealed distinct classes of pattern recognition receptors (PRRs) that detect pathogens at the cell surface and in intracellular compartments. This has shed light on how herpesviruses, which are large disease-causing DNA viruses that replicate in the nucleus, are initially recognized during cellular infection. Surprisingly, this involves multiple PRRs both on the cell surface and within endosomes and the cytosol. In this article we describe recent advances in our understanding of innate detection of herpesviruses, how this innate detection translates into anti-herpesvirus host defence, and how the viruses seek to evade this innate detection to establish persistent infections.

Anti-EBNA-1 IgG is not a reliable marker of multiple sclerosis clinical disease activity

BACKGROUND

Sero-epidemiological studies have demonstrated the association between multiple sclerosis (MS) and prior Epstein-Barr virus (EBV) infection. It has been hypothesized that intermittent peripheral EBV reactivation may drive continuing central inflammation. Recent investigation has shown significant differences in median serum levels of anti-EBV nuclear antigen-1 (EBNA-1) IgG between disease subgroups and positive correlation with disease activity reflected by number of Gd-enhancing lesions and T2 lesion volume. These important data have led to hopes that anti-EBNA-1 IgG may be useful as an easily accessible and effective biomarker of disease activity.

METHODS

We examined the applicability of these findings in routine clinical practice, assessing a well-characterized cohort of 100 subjects (25 primary progressive, 25 stable relapsing remitting, 25 active relapsing remitting seen in acute relapse and 25 controls) for serum anti-EBNA-1 IgG using both the Liaison quantitative chemiluminescent assay and Biotest ELISA.

RESULTS

We were unable to show a difference in quantitative analysis of serum anti-EBNA-1 IgG levels between disease subgroups and no correlation with phenotypic characteristics including age at onset (r = -0.17, P = 0.16), disease duration (r = 0.03, P = 0.78), EDSS (r = 0.03, P = 0.78) or MSSS (r = 0.02, P = 0.9). In addition, there was only moderate correlation between the two test methods used (intraclass correlation coefficient 0.67; 0.56-0.78) suggesting potential problems with test interpretation.

CONCLUSIONS

We have been unable to determine a clinical value for serum anti-EBNA-1 IgG levels in MS or to confirm reported association with disease course and clinical disease activity.

Viral pathophysiology of multiple sclerosis: A role for Epstein-Barr virus infection?

Multiple sclerosis (MS) is the most common inflammatory demyelinating and degenerative disease of the CNS. The cause of MS is unknown but environmental risk factors are implicated in MS. Several viruses have been proposed as a trigger for MS, and lately Epstein-Barr virus (EBV) has become the leading candidate. An infectious aetiology fits with a number of epidemiological observations in addition to the immunopathological features of the disease. In this review we will summarize the emerging evidence, which demonstrates a strong association between EBV infection and MS. The conundrum remains as to whether EBV is directly involved in the pathophysiology of MS, or alternatively if the immunopathology of MS somehow affects the regulation of EBV infection.

Interferon-β inhibits toll-like receptor 9 processing in multiple sclerosis

OBJECTIVE

Viral infections have been implicated in the pathogenesis of multiple sclerosis (MS). Plasmacytoid dendritic cells (pDCs) are present in peripheral blood, cerebrospinal fluid, and brain lesions of MS patients. pDCs sense viral DNA via Toll-like receptor 9 (TLR9), which has to be cleaved from the N-terminal to become functional (TLR9 processing). pDCs activated with TLR9 agonists promote T-helper type 1 (Th1)/T-helper type 17 (Th17) responses. In the animal model of MS, TLR9 agonists can induce disease. We hypothesized that pDCs are inhibited by disease-modifying therapy such as interferon (IFN)-β, consequently decreasing the frequency of MS attacks.

METHODS

We separated pDCs from healthy subjects and patients diagnosed with relapsing-remitting MS and clinically isolated syndrome. Cytokine secretion by pDCs activated with TLR9 agonists was measured by enzyme-linked immunosorbent assay and multianalyte profiling. TLR9 gene and protein expression was studied by DNA microarrays and western blot.

RESULTS

In untreated patients, pDCs activated with TLR9 agonists produced increased levels of IFN-α, a Th1-promoting cytokine, as compared to healthy subjects. In IFN-β-treated patients, activated pDCs had decreased ability to produce both IFN-α and the proinflammatory cytokines interleukin (IL)-6 and tumor necrosis factor α as compared to untreated patients. pDCs separated from IFN-β-treated patients had significantly reduced levels of the processed TLR9 protein but normal levels of the full-length TLR9 protein and TLR9 gene expression as compared to untreated patients.

INTERPRETATION

This finding represents a novel immunomodulatory mechanism of IFN-β: inhibition of TLR9 processing. This results in decreased activation of pDCs by viral pathogens and, thus, may affect the frequency of MS exacerbations.

Vitamin D and the anti-viral state

Vitamin D has long been recognized as essential to the skeletal system. Newer evidence suggests that it also plays a major role regulating the immune system, perhaps including immune responses to viral infection. Interventional and observational epidemiological studies provide evidence that vitamin D deficiency may confer increased risk of influenza and respiratory tract infection. Vitamin D deficiency is also prevalent among patients with HIV infection. Cell culture experiments support the thesis that vitamin D has direct anti-viral effects particularly against enveloped viruses. Though vitamin D's anti-viral mechanism has not been fully established, it may be linked to vitamin D's ability to up-regulate the anti-microbial peptides LL-37 and human beta defensin 2. Additional studies are necessary to fully elucidate the efficacy and mechanism of vitamin D as an anti-viral agent.

Temporal relationship between environmental influenza A and Epstein-Barr viral infections and high multiple sclerosis relapse occurrence

BACKGROUND

Multiple sclerosis (MS) relapses have been associated with viral and bacterial infection epidemics in MS patients who have not used interferon.

OBJECTIVES

We studied whether environmental viral infections in the general population can be associated with increased MS relapse occurrence using retrospective data from 1986 to 1995 when interferons were not yet available.

METHODS

Logistic regression modelling was used to compare retrospectively the monthly relapse occurrence from 407 MS patients in Turku University hospital archives and data on ten different specifically diagnosed viral infection epidemics in the general population of Southwestern Finland from 1986 to 1995. The outcome was the odds ratio (OR) of very high relapse occurrence versus low relapse occurrence, or moderate versus low relapse occurrence.

RESULTS

After a peak in diagnosed influenza A cases in the general population, the MS relapse occurrence was 6.5 times more likely to be very high (95% CI 1.8-24.0) and 7.1 times more likely to be moderately high (95% CI 1.5-33.2). An increase in MS relapse counts also followed Epstein-Barr virus (EBV) infections (OR 4.4, 95% CI 1.3-15.1), but we found no significant association with adenovirus infections and MS relapses. The MS relapse occurrence was lowest in the summer months July-August (Chi-square test, p<0.01).

CONCLUSIONS

Our findings suggest that influenza A and EBV viral infections in the general population are associated with a higher occurrence of exacerbations in MS patients, and thus environmental infection data should be included in epidemiological models on MS relapses.