Multiple sclerosis and infection: history, EBV, and the search for mechanism

SUMMARYInfection has long been hypothesized as the cause of multiple sclerosis (MS), and recent evidence for Epstein-Barr virus (EBV) as the trigger of MS is clear and compelling. This clarity contrasts with yet uncertain viral mechanisms and their relation to MS neuroinflammation and demyelination. As long as this disparity persists, it will invigorate virologists, molecular biologists, immunologists, and clinicians to ascertain how EBV potentiates MS onset, and possibly the disease's chronic activity and progression. Such efforts should take advantage of the diverse body of basic and clinical research conducted over nearly two centuries since the first clinical descriptions of MS plaques. Defining the contribution of EBV to the complex and multifactorial pathology of MS will also require suitable experimental models and techniques. Such efforts will broaden our understanding of virus-driven neuroinflammation and specifically inform the development of EBV-targeted therapies for MS management and, ultimately, prevention.

From progression to progress: The future of multiple sclerosis

Significant advances have been made in the diagnosis and treatment of multiple sclerosis in recent years yet challenges remain. The current classification of MS phenotypes according to disease activity and progression, for example, does not adequately reflect the underlying pathophysiological mechanisms that may be acting in an individual with MS at different time points. Thus, there is a need for clinicians to transition to a management approach based on the underlying pathophysiological mechanisms that drive disability in MS. A Canadian expert panel convened in January 2023 to discuss priorities for clinical discovery and scientific exploration that would help advance the field. Five key areas of focus included: identifying a mechanism-based disease classification system; developing biomarkers (imaging, fluid, digital) to identify pathologic processes; implementing a data-driven approach to integrate genetic/environmental risk factors, clinical findings, imaging and biomarker data, and patient-reported outcomes to better characterize the many factors associated with disability progression; utilizing precision-based treatment strategies to target different disease processes; and potentially preventing disease through Epstein-Barr virus (EBV) vaccination, counselling about environmental risk factors (e.g. obesity, exercise, vitamin D/sun exposure, smoking) and other measures. Many of the tools needed to meet these needs are currently available. Further work is required to validate emerging biomarkers and tailor treatment strategies to the needs of individual patients. The hope is that a more complete view of the individual's pathobiology will enable clinicians to usher in an era of truly personalized medicine, in which more informed treatment decisions throughout the disease course achieve better long-term outcomes.

The value of Interferon β in multiple sclerosis and novel opportunities for its anti-viral activity: a narrative literature review

Interferon-beta (IFN-β) for Multiple Sclerosis (MS) is turning 30. The COVID-19 pandemic rejuvenated the interest in interferon biology in health and disease, opening translational opportunities beyond neuroinflammation. The antiviral properties of this molecule are in accord with the hypothesis of a viral etiology of MS, for which a credible culprit has been identified in the Epstein-Barr Virus. Likely, IFNs are crucial in the acute phase of SARS-CoV-2 infection, as demonstrated by inherited and acquired impairments of the interferon response that predispose to a severe COVID-19 course. Accordingly, IFN-β exerted protection against SARS-CoV-2 in people with MS (pwMS). In this viewpoint, we summarize the evidence on IFN-β mechanisms of action in MS with a focus on its antiviral properties, especially against EBV. We synopsize the role of IFNs in COVID-19 and the opportunities and challenges of IFN-β usage for this condition. Finally, we leverage the lessons learned in the pandemic to suggest a role of IFN-β in long-COVID-19 and in special MS subpopulations.

From bedside to bench: how existing therapies inform the relationship between Epstein-Barr virus and multiple sclerosis

Therapy for relapsing-remitting multiple sclerosis (MS) has advanced dramatically despite incomplete understanding of the cause of the condition. Current treatment involves inducing broad effects on immune cell populations with consequent off-target side effects, and no treatment can completely prevent disability progression. Further therapeutic advancement will require a better understanding of the pathobiology of MS. Interest in the role of Epstein-Barr virus (EBV) in multiple sclerosis has intensified based on strong epidemiological evidence of an association between EBV seroprevalence and MS. Hypotheses proposed to explain the biological relationship between EBV and MS include molecular mimicry, EBV immortalised autoreactive B cells and infection of glial cells by EBV. Examining the interaction between EBV and immunotherapies that have demonstrated efficacy in MS offers clues to the validity of these hypotheses. The efficacy of B cell depleting therapies could be consistent with a hypothesis that EBV-infected B cells drive MS; however, loss of T cell control of B cells does not exacerbate MS. A number of MS therapies invoke change in EBV-specific T cell populations, but pathogenic EBV-specific T cells with cross-reactivity to CNS antigen have not been identified. Immune reconstitution therapies induce EBV viraemia and expansion of EBV-specific T cell clones, but this does not correlate with relapse. Much remains unknown regarding the role of EBV in MS pathogenesis. We discuss future translational research that could fill important knowledge gaps.

Interferon β1a treatment does not influence serum Epstein-Barr virus antibodies in patients with multiple sclerosis

There is increasing evidence of Epstein-Barr virus (EBV) being conditional in multiple sclerosis (MS) pathogenesis and influential for disease activity. Interferon-beta (IFNβ) is a cytokine with antiviral effects used to treat MS, in which a possible antiviral effect against EBV has been questioned. In this study, we investigated the effect of IFNβ-1a treatment on serum EBV antibody levels in 84 patients with relapsing-remitting MS. In the 18 months following IFNβ-1a treatment initiation, there were no significant associations between treatment and serum levels of Epstein-Barr nuclear antigen 1 (EBNA-1) immunoglobulin (Ig) G, early antigen (EA) IgG, viral capsid antigen (VCA) IgG or VCA IgM. The findings suggest that IFNβ-1a treatment does not influence the humoral response to EBV in patients with MS.

Epstein-Barr Virus and multiple sclerosis in a Spanish cohort: A two-years longitudinal study

Objectives

1. To analyze the prevalence and levels of anti-EBNA-1 and anti-VCA IgG antibodies of Epstein-Barr virus (EBV) in a Spanish cohort of multiple sclerosis (MS) patients and their interactions with other environmental and genetic risk factors. 2. To analyze the association of the evolution of these antibodies with the clinical response to different disease modifying therapies (DMTs) after two-years of follow-up. 3. To assess their possible correlation with the class II HLA alleles as well as with several SNPs identified in GWAS related to disease susceptibility.

Materials and methods

We recruited 325 MS patients without DMT (serum samples were collected 1-3 months before starting a therapy) and 295 healthy controls (HC). For each patient we also collected serum samples 6, 12, 18 and 24 months after starting the DMT. EBNA-1 and VCA IgG titers were analyzed by ELISA; 25(OH)D levels were analyzed by immunoassay; HLA DRB1*15:01 allelic variant was analyzed by Taqman technology.

Results

1. 97.8% (318/325) vs. 87.1% (257/295) positives for EBNA-1 in MS patients and HC, respectively (p<0.0001; O.R. = 6.7); 99.7% (324/325) vs. 94.6% (279/295) for VCA in MS patients and HC, respectively (p=0.0001; O.R. = 18.6). All MS patients were positive for EBNA-1 and/or VCA IgG antibodies vs. 280/295 (94.9%) HC (p<0.0001). IgG titers were also significantly higher in MS patients than in HC. 2. We did not find any statistical correlation in the variation of the EBNA-1 and VCA IgG titers between baseline and 24 month visits with the number of relapses, progression, clinical response, NEDA-3 condition or therapeutic failure. 3. When we compared different epidemiological and clinical variables between those with genetic factors associated with lower EBNA-1 IgG titers and all other MS patients, we found MS started 3.5 years later among the first.

Conclusions

These results confirm that MS occurs rarely in absence of EBV. An intriguing association between genetic burden and lower EBNA-1 IgG titers was associated with an earlier age of disease onset. Similar studies with B-cell–targeted therapies should be performed.

Altered Immune Response to the Epstein-Barr Virus as a Prerequisite for Multiple Sclerosis

Strong epidemiologic evidence links Epstein–Barr virus (EBV) infection and its altered immune control to multiple sclerosis (MS) development. Clinical MS onset occurs years after primary EBV infection and the mechanisms linking them remain largely unclear. This review summarizes the epidemiological evidence for this association and how the EBV specific immune control is altered in MS patients. The two main possibilities of mechanisms for this association are further discussed. Firstly, immune responses that are induced during a symptomatic primary EBV infection, namely infectious mononucleosis, might be amplified during the following years to finally cause central nervous system (CNS) inflammation and demyelination. Secondly, genetic predisposition and environmental factors might not allow for an efficient immune control of the EBV-infected B cells that might drive autoimmune T cell stimulation or CNS inflammation. These two main hypotheses for explaining the association of the EBV with MS would implicate opposite therapeutic interventions, namely either dampening CNS inflammatory EBV-reactive immune responses or strengthening them to eliminate the autoimmunity stimulating EBV-infected B cell compartment. Nevertheless, recent findings suggest that EBV is an important puzzle piece in the pathogenesis of MS, and understanding its contribution could open new treatment possibilities for this autoimmune disease.

Infections and Multiple Sclerosis: From the World to Sardinia, From Sardinia to the World

Multiple Sclerosis (MS) is an inflammatory disease of the central nervous system. Sardinia, an Italian island, is one of the areas with the highest global prevalence of MS. Genetic factors have been widely explored to explain this greater prevalence among some populations; the genetic makeup of the Sardinians appears to make them more likely to develop autoimmune diseases. A strong association between MS and some infections have been reported globally. The most robust evidence indicating the role of infections is MS development concerns the Epstein-Barr virus (EBV). Anti-EBV antibodies in patients once infected by EBV are associated with the development of MS years later. These features have also been noted in Sardinian patients with MS. Many groups have found an increased expression of the Human endogenous retroviruses (HERV) family in patients with MS. A role in pathogenesis, prognosis, and prediction of treatment response has been proposed for HERV. A European multi-centre study has shown that their presence was variable among populations, ranging from 59% to 100% of patients, with higher HERV expression noted in Sardinian patients with MS. The mycobacterium avium subspecies paratuberculosis (MAP) DNA and antibodies against MAP2694 protein were found to be associated with MS in Sardinian patients. More recently, this association has also been reported in Japanese patients with MS. In this study, we analysed the role of infectious factors in Sardinian patients with MS and compared it with the findings reported in other populations.

The cellular immune response against Epstein-Barr virus decreases during ocrelizumab treatment

BACKGROUND

Epstein-Barr Virus (EBV) is strongly associated with multiple sclerosis (MS). After initial infection, EBV maintains a life-long latent infection in B lymphocytes. Depletion of B lymphocytes from the blood with the anti-CD20 antibody ocrelizumab markedly reduces disease activity in MS. Our objective was to measure the effect of ocrelizumab treatment on the cellular immune response to EBV.

METHODS

Blood was collected from MS patients before and during ocrelizumab treatment. Peripheral blood mononuclear cells were stimulated with various antigens, and the response was measured using tritiated thymidine for proliferation and ELIspot for number of interferon-γ producing cells.

RESULTS

The proliferation to autologous EBV-infected cells (LCL) was decreased after both 6 and 12 months of treatment. The number of interferon-γ producing cells on ELIspot in response to stimulation with either LCL or EBV also decreased. Responses to varicella zoster virus, influenza virus, and a mitogen did not change significantly.

CONCLUSION

The cellular immune response to EBV and LCL decreases during treatment with ocrelizumab. The benefit of ocrelizumab for MS may be through removal of EBV antigenic stimulus.

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.

Epstein-Barr Virus in Multiple Sclerosis: Theory and Emerging Immunotherapies

New treatments for multiple sclerosis (MS) focused on B cells have created an atmosphere of excitement in the MS community. B cells are now known to play a major role in disease, demonstrated by the highly impactful effect of a B cell-depleting antibody on controlling MS. The idea that a virus may play a role in the development of MS has a long history and is supported mostly by studies demonstrating a link between B cell-tropic Epstein–Barr virus (EBV) and disease onset. Efforts to develop antiviral strategies for treating MS are underway. Although gaps remain in our understanding of the etiology of MS, the role, if any, of viruses in propagating pathogenic immune responses deserves attention.

Evidence from genome wide association studies implicates reduced control of Epstein-Barr virus infection in multiple sclerosis susceptibility

BACKGROUND

Genome wide association studies have identified > 200 susceptibility loci accounting for much of the heritability of multiple sclerosis (MS). Epstein-Barr virus (EBV), a memory B cell tropic virus, has been identified as necessary but not sufficient for development of MS. The molecular and immunological basis for this has not been established. Infected B cell proliferation is driven by signalling through the EBV produced cell surface protein LMP1, a homologue of the MS risk gene CD40.

METHODS

We have investigated transcriptomes of B cells and EBV-infected B cells at Latency III (LCLs) and identified MS risk genes with altered expression on infection and with expression levels associated with the MS risk genotype (LCLeQTLs). The association of LCLeQTL genomic burden with EBV phenotypes in vitro and in vivo was examined. The risk genotype effect on LCL proliferation with CD40 stimulation was assessed.

RESULTS

These LCLeQTL MS risk SNP:gene pairs (47 identified) were over-represented in genes dysregulated between B and LCLs (p < 1.53 × 10^-4), and as target loci of the EBV transcription factor EBNA2 (p < 3.17 × 10^-16). Overall genetic burden of LCLeQTLs was associated with some EBV phenotypes but not others. Stimulation of the CD40 pathway by CD40L reduced LCL proliferation (p < 0.001), dependent on CD40 and TRAF3 MS risk genotypes. Both CD40 and TRAF3 risk SNPs are in binding sites for the EBV transcription factor EBNA2, with expression of each correlated with EBNA2 expression dependent on genotype.

CONCLUSIONS

These data indicate targeting EBV may be of therapeutic benefit in MS.

Effect of high-dose vitamin D3 supplementation on antibody responses against Epstein–Barr virus in relapsing-remitting multiple sclerosis

Background:

Elevated antibody levels against Epstein–Barr virus (EBV) and a poor vitamin D status are environmental factors that may interact in relapsing-remitting multiple sclerosis (RRMS) aetiology.

Objectives:

To examine effects of high-dose oral vitamin D3 supplementation on antibody levels against EBV nuclear antigen 1 (EBNA1) in RRMS.

Methods:

Serum 25-hydroxyvitamin D3 (25(OH)D) and immunoglobulin G antibody levels against EBNA1 (whole protein and amino acid 385–420 fragment), EBV viral capsid antigen (VCA), cytomegalovirus (CMV) and varicella zoster virus (VZV) were measured in 68 RRMS patients enrolled in a 96-week randomised double-blinded placebo-controlled clinical trial of oral vitamin D3 supplementation (20,000 IU/week) (NCT00785473).

Results:

The mean 25(OH)D level more than doubled in the vitamin D group and was significantly higher than in the placebo group at study conclusion (123.2 versus 61.8 nmol/L, p < 0.001). Compared to the placebo group, both anti-EBNA1 protein and fragment antibody levels decreased in the vitamin D group from baseline to week 48 ( p = 0.038 and p = 0.004, respectively), but not from baseline to week 96. Vitamin D3 supplementation did not affect antibodies against VCA, CMV or VZV.

Conclusion:

The results indicate that high-dose oral vitamin D3 supplementation can affect humoral immune responses against the latent EBV antigen EBNA1 in RRMS.

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.

EBNA-1 IgG titers in Sardinian multiple sclerosis patients and controls

Multiple sclerosis (MS) is thought to be triggered by environmental factors acting on a genetic predisposition. Sardinians share a homogeneous genetic background and boast one of the highest MS prevalence worldwide. We investigated Epstein-Barr virus (EBV) antibody prevalence in Sardinian population by ELISA. Our results show a higher serum prevalence of EBNA-1 IgG in MS patients compared to healthy controls. Moreover, analyzing a subset of patients treated for 6 months with IFN-β, we observed a decrease in their EBNA-1 specific IgG titers. These results confirm previous findings and strengthen the association between EBV and MS in Sardinia.

B-cell targeting agents in the treatment of multiple sclerosis

OPINION STATEMENT

The aims of this article are to discuss the potential role of B lymphocytes in the pathogenesis of multiple sclerosis (MS) and in the mechanisms of action of approved and emerging disease modifying therapies. Over the last few years, significant progress has been made in the introduction of novel pharmacologic treatments that reduce the frequency of clinical exacerbations and radiological lesion formation in relapsing remitting MS. The mechanisms of action of a number of these disease modifying therapies (DMT) implicate B cells in the pathogenesis, as well as in the regulation, of MS. Further research into B-cell subset trafficking patterns, functional activities and interactions with other immune cells in the context of neuroinflammation is likely to inform the development of future generations of DMT.

Increased CD8+ T cell response to Epstein-Barr virus lytic antigens in the active phase of multiple sclerosis

It has long been known that multiple sclerosis (MS) is associated with an increased Epstein-Barr virus (EBV) seroprevalence and high immune reactivity to EBV and that infectious mononucleosis increases MS risk. This evidence led to postulate that EBV infection plays a role in MS etiopathogenesis, although the mechanisms are debated. This study was designed to assess the prevalence and magnitude of CD8+ T-cell responses to EBV latent (EBNA-3A, LMP-2A) and lytic (BZLF-1, BMLF-1) antigens in relapsing-remitting MS patients (n = 113) and healthy donors (HD) (n = 43) and to investigate whether the EBV-specific CD8+ T cell response correlates with disease activity, as defined by clinical evaluation and gadolinium-enhanced magnetic resonance imaging. Using HLA class I pentamers, lytic antigen-specific CD8+ T cell responses were detected in fewer untreated inactive MS patients than in active MS patients and HD while the frequency of CD8+ T cells specific for EBV lytic and latent antigens was higher in active and inactive MS patients, respectively. In contrast, the CD8+ T cell response to cytomegalovirus did not differ between HD and MS patients, irrespective of the disease phase. Marked differences in the prevalence of EBV-specific CD8+ T cell responses were observed in patients treated with interferon-β and natalizumab, two licensed drugs for relapsing-remitting MS. Longitudinal studies revealed expansion of CD8+ T cells specific for EBV lytic antigens during active disease in untreated MS patients but not in relapse-free, natalizumab-treated patients. Analysis of post-mortem MS brain samples showed expression of the EBV lytic protein BZLF-1 and interactions between cytotoxic CD8+ T cells and EBV lytically infected plasma cells in inflammatory white matter lesions and meninges. We therefore propose that inability to control EBV infection during inactive MS could set the stage for intracerebral viral reactivation and disease relapse.