Elevated Epstein-Barr virus-encoded nuclear antigen-1 immune responses predict conversion to multiple sclerosis

Enhanced and cross-reactive in vitro memory B cell response against Epstein-Barr virus nuclear antigen 1 in multiple sclerosis

Multiple sclerosis (MS) is a prototypical autoimmune disease of the central nervous system (CNS). In addition to CD4+ T cells, memory B cells are now recognized as a critical cell type in the disease. This is underlined by the fact that the best-characterized environmental risk factor for MS is the Epstein-Barr virus (EBV), which can infect and persist in memory B cells throughout life. Several studies have identified changes in anti-EBV immunity in patients with MS. Examples include elevated titers of anti-EBV nuclear antigen 1 (EBNA1) antibodies, interactions of these with the MS-associated HLA-DR15 haplotype, and molecular mimicry with MS autoantigens like myelin basic protein (MBP), anoctamin-2 (ANO2), glial cell adhesion molecule (GlialCAM), and alpha-crystallin B (CRYAB). In this study, we employ a simple in vitro assay to examine the memory B cell antibody repertoire in MS patients and healthy controls. We replicate previous serological data from MS patients demonstrating an increased secretion of anti-EBNA1380-641 IgG in cell culture supernatants, as well as a positive correlation of these levels with autoantibodies against GlialCAM262-416 and ANO21-275. For EBNA1380-641 and ANO21-275, we provide additional evidence suggesting antibody cross-reactivity between the two targets. Further, we show that two efficacious MS treatments - natalizumab (NAT) and autologous hematopoietic stem cell transplantation (aHSCT) - are associated with distinct changes in the EBNA1-directed B cell response and that these alterations can be attributed to the unique mechanisms of action of these therapies. Using an in vitro system, our study confirms MS-associated changes in the anti-EBNA1 memory B cell response, EBNA1380-641 antibody cross-reactivity with ANO21-275, and reveals treatment-associated changes in the immunoglobulin repertoire in MS.

A two-years real-word study with fingolimod: early predictors of efficacy and an association between EBNA-1 IgG titers and multiple sclerosis progression

Background

Although fingolimod, a sphingosine 1-phosphate receptor agonist, has shown to be an effective treatment reducing relapse rate and also slowing down the disability progression in relapsing-remitting multiple sclerosis (RRMS) patients, it is important to quickly identify those suboptimal responders.

Objective

The main objective was to assess different clinical, radiological, genetic and environmental factors as possible early predictors of response in MS patients treated with fingolimod for 24 months. The secondary objective was to analyze the possible contribution of the environmental factors analyzed to the progression and activity of the disease along the 2-years of follow-up.

Methods

A retrospective study with 151 patients diagnosed with MS, under fingolimod treatment for 24 months, with serum samples at initiation and six months later, and with clinical and radiological data at initiation and 24 months later, were included in the study. Clinical and radiological variables were collected to establish NEDA-3 (no evidence of disease activity: patients without relapses, disability progression and new T2 lesions or Gd+ lesions) and EDA (evidence of disease activity: patients with relapses and/or progression and/or new T2 lesions or gadolinium-positive [Gd+] lesions) conditions. Human leukocyte antigen II (HLA-II), EBNA-1 IgG and VCA IgG from Epstein-Barr virus (EBV) and antibody titers against Human herpesvirus 6A/B (HHV-6A/B) were also analyzed.

Results

A total of 151 MS patients fulfilled the inclusion criteria: 27.8% was NEDA-3 (37.5% among those previously treated with high efficacy therapies >24 months). The following early predictors were statistically significantly associated with NEDA-3 condition: sex (male; p=0.002), age at baseline (older; p=0.009), relapses 2-years before fingolimod initiation ≤1 (p=0.010), and absence of Gd+ lesions at baseline (p=0.006). Regarding the possible contribution of the environmental factors included in the study to the activity or the progression of the disease, we only found that EBNA-1 IgG titers decreased in 20.0% of PIRA (progression independent from relapse activity) patients vs. 73.3% of RAW (relapse-associated worsening) patients (p=0.006; O.R. = 11.0).

Conclusion

MS patients that are male, older, and with a low clinical and radiological activity at fingolimod initiation have a greater probability to reach NEDA-3 condition after two years with this therapy. An intriguing association of EBV with the progression of the disease has also been described, but it should be further study in a larger cohort to confirm these results.

Heightened Epstein-Barr virus immunity and potential cross-reactivities in multiple sclerosis

BACKGROUND

Epstein-Barr virus (EBV) is a likely prerequisite for multiple sclerosis (MS) but the underlying mechanisms are unknown. We investigated antibody and T cell responses to EBV in persons with MS (pwMS), healthy EBV-seropositive controls (HC) and post-infectious mononucleosis (POST-IM) individuals up to 6 months after disease resolution. The ability of EBV-specific T cell responses to target antigens from the central nervous system (CNS) was also investigated.

METHODS

Untreated persons with relapsing-remitting MS, POST-IM individuals and HC were, as far as possible, matched for gender, age and HLA-DRB1*15:01. EBV load was determined by qPCR, and IgG responses to key EBV antigens were determined by ELISA, immunofluorescence and Western blot, and tetanus toxoid antibody responses by multiplex bead array. EBV-specific T cell responses were determined ex vivo by intracellular cytokine staining (ICS) and cross-reactivity of in vitro-expanded responses probed against 9 novel Modified Vaccinia Ankara (MVA) viruses expressing candidate CNS autoantigens.

RESULTS

EBV load in peripheral blood mononuclear cells (PBMC) was unchanged in pwMS compared to HC. Serologically, while tetanus toxoid responses were unchanged between groups, IgG responses to EBNA1 and virus capsid antigen (VCA) were significantly elevated (EBNA1 p = 0.0079, VCA p = 0.0298) but, importantly, IgG responses to EBNA2 and the EBNA3 family antigens were also more frequently detected in pwMS (EBNA2 p = 0.042 and EBNA3 p = 0.005). In ex vivo assays, T cell responses to autologous EBV-transformed B cells and to EBNA1 were largely unchanged numerically, but significantly increased IL-2 production was observed in response to certain stimuli in pwMS. EBV-specific polyclonal T cell lines from both MS and HC showed high levels of autoantigen recognition by ICS, and several neuronal proteins emerged as common targets including MOG, MBP, PLP and MOBP.

DISCUSSION

Elevated serum EBV-specific antibody responses in the MS group were found to extend beyond EBNA1, suggesting a larger dysregulation of EBV-specific antibody responses than previously recognised. Differences in T cell responses to EBV were more difficult to discern, however stimulating EBV-expanded polyclonal T cell lines with 9 candidate CNS autoantigens revealed a high level of autoreactivity and indicate a far-reaching ability of the virus-induced T cell compartment to damage the CNS.

Altered EBV specific immune control in multiple sclerosis

Since the 1980s it is known that immune responses to the Epstein-Barr virus (EBV) are elevated in multiple sclerosis (MS) patients. Recent seroepidemiologial data have shown that this alteration after primary EBV infection identifies individuals with a more than 30-fold increased risk to develop MS. The mechanisms by which EBV infection might erode tolerance for the central nervous system (CNS) in these individuals, years prior to clinical MS onset, remain unclear. In this review I will discuss altered frequencies of EBV life cycle stages and their tissue distribution, EBV with CNS autoantigen cross-reactive immune responses and loss of immune control for autoreactive B and T cells as possible mechanisms. This discussion is intended to stimulate future studies into these mechanisms with the aim to identify candidates for interventions that might correct EBV specific immune control and/or resulting cross-reactivities with CNS autoantigens in MS patients and thereby ameliorate disease activity.

Evaluating the Clinical Utility of Epstein-Barr Virus Antibodies as Biomarkers in Multiple Sclerosis: A Systematic Review

BACKGROUND

EBV is a necessary but not sufficient factor in the pathophysiology of multiple sclerosis (MS). EBV antibodies to the nuclear antigen (EBNA1) and viral capsid antigen (VCA) rise rapidly prior to MS disease manifestations, and their absence has clinical utility with a high negative predictive value. It remains unclear whether EBV levels act as prognostic, monitoring, or pharmacodynamic/response biomarkers. Substantial literature on this topic exists but has not been systematically reviewed. We hypothesized that EBV levels against EBNA1 and VCA are potential prognostic and monitoring biomarkers in MS, and that patient population, MS clinical phenotype, and EBV assay method may play important roles in explaining variation among study outcomes.

METHODS

We systematically searched PubMed and EMBASE from inception to April 1, 2022. After removal of duplicates, records were screened by abstract. Remaining full-text articles were reviewed. Clinical and MRI data were extracted from full-text articles for comparison and synthesis.

RESULTS

Searches yielded 696 unique results; 285 were reviewed in full, and 36 met criteria for data extraction. Heterogeneity in sample population, clinical outcome measures, assay methods and statistical analyses precluded a meta-analysis. EBV levels were not consistently associated with clinical disease markers including conversion from CIS to RRMS, neurological disability, or disease phenotype. Studies using repeated-measures design suggest that EBNA1 levels may temporarily reflect inflammatory disease activity as assessed by gadolinium-enhancing Magnetic Resonance Imaging (MRI) lesions. Limited data also suggest a decrease in EBV levels following initiation of certain disease-modifying therapies.

CONCLUSION

Heterogeneous methodology limited generalization and meta-analysis. EBV antibody levels are unlikely to represent prognostic biomarkers in MS. The areas of highest ongoing promise relate to diagnostic exclusion and pharmacodynamic/disease response. Use of EBV antibodies as biomarkers in clinical practice remains additionally limited by lack of methodological precision, reliability, and validation.

Multiple Sclerosis: An Emergency Medicine-Focused Narrative Review

BACKGROUND

Multiple sclerosis (MS) is a rare but serious condition associated with significant morbidity.

OBJECTIVE

This review provides a focused assessment of MS for emergency clinicians, including the presentation, evaluation, and emergency department (ED) management based on current evidence.

DISCUSSION

MS is an autoimmune disorder targeting the central nervous system (CNS), characterized by clinical relapses and radiological lesions disseminated in time and location. Patients with MS most commonly present with long tract signs (e.g., myelopathy, asymmetric spastic paraplegia, urinary dysfunction, Lhermitte's sign), optic neuritis, or brainstem syndromes (bilateral internuclear ophthalmoplegia). Cortical syndromes or multifocal presentations are less common. Radiologically isolated syndrome and clinically isolated syndrome (CIS) may or may not progress to chronic forms of MS, including relapsing remitting MS, primary progressive MS, and secondary progressive MS. The foundation of outpatient management involves disease-modifying therapy, which is typically initiated with the first signs of disease onset. Management of CIS and acute flares of MS in the ED includes corticosteroid therapy, ideally after diagnostic testing with imaging and lumbar puncture for cerebrospinal fluid analysis. Emergency clinicians should evaluate whether patients with MS are presenting with new-onset debilitating neurological symptoms to avoid unnecessary testing and admissions, but failure to appropriately diagnose CIS or MS flare is associated with increased morbidity.

CONCLUSIONS

An understanding of MS can assist emergency clinicians in better diagnosing and managing this neurologically devastating disease.

Seroreactivity against lytic, latent and possible cross-reactive EBV antigens appears on average 10 years before MS induced preclinical neuroaxonal damage

BACKGROUND

Multiple sclerosis (MS) and presymptomatic axonal injury appear to develop only after an Epstein-Barr virus (EBV) infection. This association remains to be confirmed across a broad preclinical time range, for lytic and latent EBV seroreactivity, and for potential cross-reacting antigens.

METHODS

We performed a case-control study with 669 individual serum samples obtained before clinical MS onset, identified through cross-linkage with the Swedish MS register. We assayed antibodies against EBV nuclear antigen 1 (EBNA1), viral capsid antigen p18, glycoprotein 350 (gp350), the potential cross-reacting protein anoctamin 2 (ANO2) and the level of sNfL, a marker of axonal injury.

RESULTS

EBNA1 (latency) seroreactivity increased in the pre-MS group, at 15-20 years before clinical MS onset, followed by gp350 (lytic) seroreactivity (p=0.001-0.009), ANO2 seropositivity appeared shortly after EBNA1-seropositivity in 16.7% of pre-MS cases and 10.0% of controls (p=0.001).With an average lag of almost a decade after EBV, sNfL gradually increased, mainly in the increasing subgroup of seropositive pre-MS cases (p=8.10-5 compared with non-MS controls). Seropositive pre-MS cases reached higher sNfL levels than seronegative pre-MS (p=0.038). In the EBNA1-seropositive pre-MS group, ANO2 seropositive cases had 26% higher sNfL level (p=0.0026).

CONCLUSIONS

Seroreactivity against latent and lytic EBV antigens, and in a subset ANO2, was detectable on average a decade before the appearance of a gradually increasing axonal injury occurring in the last decade before the onset of clinical MS. These findings strengthen the hypothesis of latent EBV involvement in the pathogenesis of MS.

Understanding the link between neurotropic viruses, BBB permeability, and MS pathogenesis

Neurotropic viruses can infiltrate the CNS by crossing the blood-brain barrier (BBB) through various mechanisms including paracellular, transcellular, and "Trojan horse" mechanisms during leukocyte diapedesis. These viruses belong to several families, including retroviruses; human immunodeficiency virus type 1 (HIV-1), flaviviruses; Japanese encephalitis (JEV); and herpesviruses; herpes simplex virus type 1 (HSV-1), Epstein-Barr virus (EBV), and mouse adenovirus 1 (MAV-1). For entering the brain, viral proteins act upon the tight junctions (TJs) between the brain microvascular endothelial cells (BMECs). For instance, HIV-1 proteins, such as glycoprotein 120, Nef, Vpr, and Tat, disrupt the BBB and generate a neurotoxic effect. Recombinant-Tat triggers amendments in the BBB by decreasing expression of the TJ proteins such as claudin-1, claudin-5, and zona occludens-1 (ZO-1). Thus, the breaching of BBB has been reported in myriad of neurological diseases including multiple sclerosis (MS). Neurotropic viruses also exhibit molecular mimicry with several myelin sheath proteins, i.e., antibodies against EBV nuclear antigen 1 (EBNA1) aa411-426 cross-react with MBP and EBNA1 aa385-420 was found to be associated with MS risk haplotype HLA-DRB1*150. Notably, myelin protein epitopes (PLP139-151, MOG35-55, and MBP87-99) are being used to generate model systems for MS such as experimental autoimmune encephalomyelitis (EAE) to understand the disease mechanism and therapeutics. Viruses like Theiler's murine encephalomyelitis virus (TMEV) are also commonly used to generate EAE. Altogether, this review provide insights into the viruses' association with BBB leakiness and MS along with possible mechanistic details which could potentially use for therapeutics.

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.

Ineffective control of Epstein-Barr-virus-induced autoimmunity increases the risk for multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the CNS. Epstein-Barr virus (EBV) contributes to the MS pathogenesis because high levels of EBV EBNA386-405-specific antibodies cross react with the CNS-derived GlialCAM370-389. However, it is unclear why only some individuals with such high autoreactive antibody titers develop MS. Here, we show that autoreactive cells are eliminated by distinct immune responses, which are determined by genetic variations of the host, as well as of the infecting EBV and human cytomegalovirus (HCMV). We demonstrate that potent cytotoxic NKG2C+ and NKG2D+ natural killer (NK) cells and distinct EBV-specific T cell responses kill autoreactive GlialCAM370-389-specific cells. Furthermore, immune evasion of these autoreactive cells was induced by EBV-variant-specific upregulation of the immunomodulatory HLA-E. These defined virus and host genetic pre-dispositions are associated with an up to 260-fold increased risk of MS. Our findings thus allow the early identification of patients at risk for MS and suggest additional therapeutic options against MS.

Humoral response to Epstein-Barr virus in patients with multiple sclerosis treated with B cell depletion therapy

BACKGROUND

B cell depletion therapy is highly effective in relapsing-remitting multiple sclerosis (RRMS). However, the precise underlying mechanisms of action for its biological effects in MS have still not been clarified. Epstein-Barr virus (EBV) is a known risk factor for MS and seems to be a prerequisite for disease development. EBV resides latently in the memory B cells, and may not only increase the risk of developing MS, but also contribute to disease activity and disability progression. Therefore, the effects of B cell depletion in MS could be associated with the depletion of EBV-infected cells and the altered immune response to the virus. In this study, we investigate the impact of B cell depletion on the humoral immune response specific to EBV in patients with MS.

METHODS

Newly diagnosed, treatment-naïve patients with RRMS were followed up to 18 months after initiation of B-cell depletion therapy in the Overlord-MS study, a phase III trial (NCT04578639). We analyzed serum sampled before treatment and after 3, 6, 12 and 18 months for immunoglobulin γ (IgG) against Epstein-Barr nuclear antigen 1 (EBNA1) and Epstein-Barr viral capsid antigen (VCA). We analyzed antibodies to cytomegalovirus (CMV) and total IgG in serum, as controls for viral and overall humoral immunity. The risk allele, HLA-DRB1*15:01, and the protective allele, HLA-A*02:01, were determined in all participants. In addition, polymerase chain reaction (PCR) for circulating EBV-DNA was performed in the first 156 samples drawn. The associations between time on B cell-depletion therapy and serum anti-EBV antibody levels were estimated using linear mixed-effects models.

RESULTS

A total of 290 serum samples from 99 patients were available for analysis. After 6, 12 and 18 months, the EBNA1 IgG levels decreased by 12.7 % (95 % CI -18.8 to -6.60, p < 0.001), 12.1 % (95 % CI -19.8 to -3.7, p = 0.006) and 14.6 % (95 % CI to -25.3 to -2.4, p = 0.02) respectively, compared to baseline level. Carriers of the HLA-DRB1*15:01 allele had higher EBNA1 IgG levels at baseline (p = 0.02). The VCA IgG levels significantly increased by 13.7 % (95 % CI 9.4 to 18.1, p < 0.001) after 3 months, compared to baseline, and persisted at this level throughout the follow-up. CMV IgG levels decreased, but to a lesser extent than the decrease of EBNA1 IgG, and total IgG levels decreased during therapy. Circulating EBV-DNA was found in only three of 156 samples from 64 patients.

CONCLUSIONS

EBNA1 IgG levels decreased, while VCA IgG levels increased, during B cell depletion therapy. This supports the hypothesis that the mechanism of action for B cell depletion therapy might be mediated by effects on EBV infection, which, in turn, mitigate immune cross-reactivity and disease perpetuation.

Diversification and expansion of the EBV-reactive cytotoxic T lymphocyte repertoire following autologous haematopoietic stem cell transplant for multiple sclerosis

Both genetic susceptibility and environmental exposures are thought to be involved in multiple sclerosis (MS) pathogenesis. Of all viruses potentially relevant to MS aetiology, Epstein-Barr virus (EBV) is the best-studied. EBV is a B cell lymphotropic virus which is able to evade the immune system by establishing latent infection in memory B cells, and EBV reactivation is restricted by CD8 cytotoxic T cell (CTL) responses in immune competent individuals. Autologous haematopoietic stem cell transplantation (AHSCT) is considered to be the most effective therapy in the treatment of relapsing MS even though chemotherapy-induced lymphopenia can associate with the re-emergence of latent viruses. Despite the increasing interest in EBV and MS pathogenesis the relationship between AHSCT, EBV and viral immunity in people with MS has not been investigated to date. This study analysed immune responses to EBV in a well characterised cohort of 13 individuals with MS by utilising pre-AHSCT, and 6-, 12- and 24-month post AHSCT bio-banked peripheral blood mononuclear cells and plasma samples. It is demonstrated that the infused stem cell product contains latently EBV-infected memory B cells, and that EBV viremia occurs in the immune-compromised recipient post-transplant. High throughput TCR analysis detected expansion and diversification of the CD8 CTL responses reactive with EBV lytic and latent antigens from 6 to 24 months following AHSCT. Increased levels of latent EBV infection found within the B cell pool following treatment, as measured by EBV genomic detection, did not associate with disease relapse. This is the first study of EBV immunity following application of AHSCT in the treatment of MS and not only raises important questions about the role of EBV infection in MS pathogenesis, but is of clinical importance given the expanding clinical trials of adoptive EBV-specific CTLs in MS.

Conversion Predictors of Clinically Isolated Syndrome to Multiple Sclerosis in Mexican Patients: A Prospective Study

BACKGROUND

Clinically Isolated Syndrome (CIS) is the first clinical episode suggestive of Clinical Definite Multiple Sclerosis (CDMS). There are no reports on possible predictors of conversion to CDMS in Mexican mestizo patients.

AIM OF THE STUDY

To investigate immunological markers, clinical and paraclinical findings, and the presence of herpesvirus DNA to predict the transition from CIS to CDMS in Mexican patients.

METHODS

A single-center prospective cohort study was conducted with newly diagnosed patients with CIS in Mexico between 2006 and 2010. Clinical information, immunophenotype, serum cytokines, anti-myelin protein immunoglobulins, and herpes viral DNA were determined at the time of diagnosis.

RESULTS

273 patients diagnosed with CIS met the enrolment criteria; after 10 years of follow-up, 46% met the 2010 McDonald criteria for CDMS. Baseline parameters associated with conversion to CDMS were motor symptoms, multifocal syndromes, and alterations of somatosensory evoked potentials. The presence of at least one lesion on magnetic resonance imaging was the main factor associated with an increased risk of conversion to CDMS (RR 15.52, 95% CI 3.96-60.79, p = 0.000). Patients who converted to CDMS showed a significantly lower percentage of circulating regulatory T cells, cytotoxic T cells, and B cells, and the conversion to CDMS was associated with the presence of varicella-zoster virus and herpes simplex virus 1 DNA in cerebrospinal fluid and blood.

CONCLUSION

There is scarce evidence in Mexico regarding the demographic and clinical aspects of CIS and CDMS. This study shows several predictors of conversion to CDMS to be considered in Mexican patients with CIS.

Markers of Epstein-Barr Virus Infection in Patients with Multiple Sclerosis

Viral infections have been suspected of being involved in the pathogenesis of certain autoimmune diseases for many years. Epstein-Barr virus (EBV), a DNA virus belonging to the Herpesviridae family, is thought to be associated with the onset and/or the progression of multiple sclerosis (MS), systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome and type 1 diabetes. The lifecycle of EBV consists of lytic cycles and latency programmes (0, I, II and III) occurring in infected B-cells. During this lifecycle, viral proteins and miRNAs are produced. This review provides an overview of the detection of EBV infection, focusing on markers of latency and lytic phases in MS. In MS patients, the presence of latency proteins and antibodies has been associated with lesions and dysfunctions of the central nervous system (CNS). In addition, miRNAs, expressed during lytic and latency phases, may be detected in the CNS of MS patients. Lytic reactivations of EBV can occur in the CNS of patients as well, with the presence of lytic proteins and T-cells reacting to this protein in the CNS of MS patients. In conclusion, markers of EBV infection can be found in MS patients, which argues in favour of a relationship between EBV and MS.

The Role of Viral Infections in the Onset of Autoimmune Diseases

Autoimmune diseases (AIDs) are the consequence of a breach in immune tolerance, leading to the inability to sufficiently differentiate between self and non-self. Immune reactions that are targeted towards self-antigens can ultimately lead to the destruction of the host's cells and the development of autoimmune diseases. Although autoimmune disorders are comparatively rare, the worldwide incidence and prevalence is increasing, and they have major adverse implications for mortality and morbidity. Genetic and environmental factors are thought to be the major factors contributing to the development of autoimmunity. Viral infections are one of the environmental triggers that can lead to autoimmunity. Current research suggests that several mechanisms, such as molecular mimicry, epitope spreading, and bystander activation, can cause viral-induced autoimmunity. Here we describe the latest insights into the pathomechanisms of viral-induced autoimmune diseases and discuss recent findings on COVID-19 infections and the development of AIDs.

Epstein-Barr virus as a leading cause of multiple sclerosis: mechanisms and implications

Epidemiological studies have provided compelling evidence that multiple sclerosis (MS) is a rare complication of infection with the Epstein-Barr virus (EBV), a herpesvirus that infects more than 90% of the global population. This link was long suspected because the risk of MS increases markedly after infectious mononucleosis (symptomatic primary EBV infection) and with high titres of antibodies to specific EBV antigens. However, it was not until 2022 that a longitudinal study demonstrated that MS risk is minimal in individuals who are not infected with EBV and that it increases over 30-fold following EBV infection. Over the past few years, a number of studies have provided clues on the underlying mechanisms, which might help us to develop more targeted treatments for MS. In this Review, we discuss the evidence linking EBV to the development of MS and the mechanisms by which the virus is thought to cause the disease. Furthermore, we discuss implications for the treatment and prevention of MS, including the use of antivirals and vaccines.

Increased cytomegalovirus immune responses at disease onset are protective in the long-term prognosis of patients with multiple sclerosis

OBJECTIVE

It remains unclear whether viral infections interfere with multiple sclerosis (MS) disease progression. We evaluated the prognostic role of antibody responses toward viruses determined at disease onset on long-term disease outcomes.

METHODS

Humoral immune responses against Epstein-Barr virus (EBV)-encoded nuclear antigen EBNA1, viral capsid antigen (VCA) and early antigen, and toward cytomegalovirus (HCMV), human herpesvirus 6 and measles were investigated in a cohort of 143 patients with MS for their association with long-term disability and inflammation disease outcomes.

RESULTS

Median (IQR) follow-up was 20 (17.2-22.8) years. In univariable analysis, increased HCMV levels were associated with a lower risk to Expanded Disability Status Scale 4.0 (HR 0.95; 95% CI 0.91 to 0.99; p=0.03), to develop a secondary progressive MS (HR 0.94; 95% CI 0.90 to 0.99; p=0.02) and to first-line treatment (HR 0.98; 95% CI 0.96 to 0.99; p=0.04). High HCMV IgG levels were associated with a longer time to first-line treatment (p=0.01). Increased immune responses against EBV-VCA were associated with higher risk for first-line (HR 1.45; 95% CI 1.12 to 1.88; p=0.005) and second-line treatments (HR 2.03; 95% CI 1.18 to 3.49; p=0.01), and high VCA IgG levels were associated with shorter time to first-line (p=0.004) and second-line (p=0.02) therapies. EBNA1-specific IgG levels correlated with disease severity (0.17; p=0.04) and with an increased relapse rate during follow-up (relapse rate 1.26; 95% CI 1.03 to 1.56; p=0.02) that remained stable in multivariable analysis.

CONCLUSIONS

These results indicate that elevated immune responses against HCMV at disease onset have protective effects on long-term disability and inflammation disease outcomes. Our data also indicate that increased immune responses against EBV in early phases may influence long-term disease prognosis.

Dimethyl Fumarate Treatment Reduces the Amount but Not the Avidity of the Epstein-Barr Virus Capsid-Antigen-Specific Antibody Response in Multiple Sclerosis: A Pilot Study

(1) Multiple sclerosis (MS) is a chronic inflammatory disease of autoimmune origin. The Epstein−Barr virus (EBV) is associated with the onset of MS, as almost all patients have high levels of EBV-specific antibodies as a result of a previous infection. We evaluated longitudinally the effects of dimethyl fumarate (DMF), a first-line treatment of MS, on the quantity and quality of EBV-specific IgG in MS patients. (2) Serum samples from 17 MS patients receiving DMF were taken before therapy (T0) and after 1 week (T1) and 1 (T2), 3 (T3) and 6 (T4) months of treatment. Anti-EBV nuclear antigen (EBNA)-1 and capsid antigen (CA) IgG levels and anti-CA IgG avidity were measured in all samples. (3) Serum levels of anti-CA IgG were lower at T1 (p = 0.0341), T2 (p = 0.0034), T3 (p < 0.0001) and T4 (p = 0.0023) than T0. These differences were partially confirmed also in anti-EBNA-1 IgG levels (T3 vs. T0, p = 0.0034). All patients had high-avidity anti-CA IgG at T0, and no changes were observed during therapy. (4): DMF can reduce the amount but not the avidity of the anti-EBV humoral immune response in MS patients from the very early stages of treatment.

Anti-CD20 therapies in multiple sclerosis: From pathology to the clinic

The immune system plays a significant role in multiple sclerosis. While MS was historically thought to be T cell-mediated, multiple pieces of evidence now support the view that B cells are essential players in multiple sclerosis pathogenic processes. High-efficacy disease-modifying therapies that target the immune system have emerged over the past two decades. Anti-CD20 monoclonal antibodies selectively deplete CD20+ B and CD20+ T cells and efficiently suppress inflammatory disease activity. These monotherapies prevent relapses, reduce new or active magnetic resonance imaging brain lesions, and lessen disability progression in patients with relapsing multiple sclerosis. Rituximab, ocrelizumab, and ofatumumab are currently used in clinical practice, while phase III clinical trials for ublituximab have been recently completed. In this review, we compare the four anti-CD20 antibodies in terms of their mechanisms of action, routes of administration, immunological targets, and pharmacokinetic properties. A deeper understanding of the individual properties of these molecules in relation to their efficacy and safety profiles is critical for their use in clinical practice.

Potential biological contributers to the sex difference in multiple sclerosis progression

Multiple sclerosis (MS) is an immune-mediated disease that targets the myelin sheath of central nervous system (CNS) neurons leading to axon injury, neuronal death, and neurological progression. Though women are more highly susceptible to developing MS, men that develop this disease exhibit greater cognitive impairment and accumulate disability more rapidly than women. Magnetic resonance imaging and pathology studies have revealed that the greater neurological progression seen in males correlates with chronic immune activation and increased iron accumulation at the rims of chronic white matter lesions as well as more intensive whole brain and grey matter atrophy and axon loss. Studies in humans and in animal models of MS suggest that male aged microglia do not have a higher propensity for inflammation, but may become more re-active at the rim of white matter lesions as a result of the presence of pro-inflammatory T cells, greater astrocyte activation or iron release from oligodendrocytes in the males. There is also evidence that remyelination is more efficient in aged female than aged male rodents and that male neurons are more susceptible to oxidative and nitrosative stress. Both sex chromosome complement and sex hormones contribute to these sex differences in biology.

The immunology of multiple sclerosis

Our incomplete understanding of the causes and pathways involved in the onset and progression of multiple sclerosis (MS) limits our ability to effectively treat this complex neurological disease. Recent studies explore the role of immune cells at different stages of MS and how they interact with cells of the central nervous system (CNS). The findings presented here begin to question the exclusivity of an antigen-specific cause and highlight how seemingly distinct immune cell types can share common functions that drive disease. Innovative techniques further expose new disease-associated immune cell populations and reinforce how environmental context is critical to their phenotype and subsequent role in disease. Importantly, the differentiation of immune cells into a pathogenic state is potentially reversible through therapeutic manipulation. As such, understanding the mechanisms that provide plasticity to causal cell types is likely key to uncoupling these disease processes and may identify novel therapeutic targets that replace the need for cell ablation.

Epstein-Barr virus infection, B-cell dysfunction and other risk factors converge in gut-associated lymphoid tissue to drive the immunopathogenesis of multiple sclerosis: a hypothesis

Multiple sclerosis is associated with Epstein-Barr virus (EBV) infection, B-cell dysfunction, gut dysbiosis, and environmental and genetic risk factors, including female sex. A disease model incorporating all these factors remains elusive. Here, we hypothesise that EBV-infected memory B cells (MBCs) migrate to gut-associated lymphoid tissue (GALT) through EBV-induced expression of LPAM-1, where they are subsequently activated by gut microbes and/or their products resulting in EBV reactivation and compartmentalised anti-EBV immune responses. These responses involve marginal zone (MZ) B cells that activate CD4⁺ T-cell responses, via HLA-DRB1, which promote downstream B-cell differentiation towards CD11c⁺/T-bet⁺ MBCs, as well as conventional MBCs. Intrinsic expression of low-affinity B-cell receptors (BCRs) by MZ B cells and CD11c⁺/T-bet⁺ MBCs promotes polyreactive BCR/antibody responses against EBV proteins (e.g. EBNA-1) that cross-react with central nervous system (CNS) autoantigens (e.g. GlialCAM). EBV protein/autoantigen-specific CD11c⁺/T-bet⁺ MBCs migrate to the meningeal immune system and CNS, facilitated by their expression of CXCR3, and induce cytotoxic CD8⁺ T-cell responses against CNS autoantigens amplified by BAFF, released from EBV-infected MBCs. An increased abundance of circulating IgA⁺ MBCs, observed in MS patients, might also reflect GALT-derived immune responses, including disease-enhancing IgA antibody responses against EBV and gut microbiota-specific regulatory IgA⁺ plasma cells. Female sex increases MZ B-cell and CD11c⁺/T-bet⁺ MBC activity while environmental risk factors affect gut dysbiosis. Thus, EBV infection, B-cell dysfunction and other risk factors converge in GALT to generate aberrant B-cell responses that drive pathogenic T-cell responses in the CNS.

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.

A Scoping Review on Body Fluid Biomarkers for Prognosis and Disease Activity in Patients with Multiple Sclerosis

Multiple sclerosis (MS) is a complex demyelinating disease of the central nervous system, presenting with different clinical forms, including clinically isolated syndrome (CIS), which is a first clinical episode suggestive of demyelination. Several molecules have been proposed as prognostic biomarkers in MS. We aimed to perform a scoping review of the potential use of prognostic biomarkers in MS clinical practice. We searched MEDLINE up to 25 November 2021 for review articles assessing body fluid biomarkers for prognostic purposes, including any type of biomarkers, cell types and tissues. Original articles were obtained to confirm and detail the data reported by the review authors. We evaluated the reliability of the biomarkers based on the sample size used by various studies. Fifty-two review articles were included. We identified 110 molecules proposed as prognostic biomarkers. Only six studies had an adequate sample size to explore the risk of conversion from CIS to MS. These confirm the role of oligoclonal bands, immunoglobulin free light chain and chitinase CHI3L1 in CSF and of serum vitamin D in the prediction of conversion from CIS to clinically definite MS. Other prognostic markers are not yet explored in adequately powered samples. Serum and CSF levels of neurofilaments represent a promising biomarker.

Serum IgG levels to Epstein-Barr and measles viruses in patients with multiple sclerosis during natalizumab and interferon beta treatment

Background

Patients with multiple sclerosis (MS) demonstrate higher seroprevalence of Epstein-Barr virus (EBV) and increased anti-EBV IgG levels in serum compared with healthy controls. Intrathecal antibody production to measles virus (MeV) is a common finding in patients with MS.

Objective

To measure serum IgG reactivity to EBV glycoprotein 350 (gp350) and MeV nucleocapsid protein (N_CORE) in patients with MS and healthy controls and to determine if reactivity changed in patients during interferon beta (IFNβ) and/or natalizumab (NAT) treatment. A secondary aim was to determine the seroprevalence of EBV in patients and controls.

Methods

Patients with MS (n=728) were included from the Swedish pharmacovigilance study for NAT. Paired serum samples from 714 patients drawn before and during NAT treatment and paired samples from 170 patients during prior IFNβ treatment were analysed. In total, 156 patients were included in both groups. Samples from 144 matched blood donors served as controls. Indirect ELISA was applied using recombinant EBVgp350 and MeV N_CORE as antigens. EBVgp350 IgG seronegative samples were also analysed using EBV nuclear antigen 1 and viral capsid antigen (VCA).

Results

Patients with MS showed higher serum levels of anti-EBVgp350 and anti-MeV N_CORE IgG compared with controls. During NAT treatment, the levels of anti-EBVgp350 and anti-MeV N_CORE IgG declined, compared with the relatively stable levels noted during prior IFNβ treatment. Ten patients failed to demonstrate anti-EBVgp350 IgG but did show detectable anti-VCA IgG, indicating EBV seropositivity. In contrast, 10/144 controls were EBV seronegative.

Conclusions

Treatment with NAT, which is considered a selective immunosuppressive agent with a compartmentalised effect on the central nervous system, appeared to be associated with a moderate decrease in circulating IgG levels to EBVgp350 and MeV N_CORE. All patients with MS were EBV IgG seropositive, supporting the potential role of EBV in the pathogenesis of MS.

The role of the complement system in Multiple Sclerosis: A review

The complement system has been involved in the pathogenesis of multiple neuroinflammatory and neurodegenerative conditions. In this review, we evaluated the possible role of complement activation in multiple sclerosis (MS) with a focus in progressive MS, where the disease pathogenesis remains to be fully elucidated and treatment options are limited. The evidence for the involvement of the complement system in the white matter plaques and gray matter lesions of MS stems from immunohistochemical analysis of post-mortem MS brains, in vivo serum and cerebrospinal fluid biomarker studies, and animal models of Experimental Autoimmune Encephalomyelitis (EAE). Complement knock-out studies in these animal models have revealed that this system may have a “double-edge sword” effect in MS. On the one hand, complement proteins may aid in promoting the clearance of myelin degradation products and other debris through myeloid cell-mediated phagocytosis. On the other, its aberrant activation may lead to demyelination at the rim of progressive MS white matter lesions as well as synapse loss in the gray matter. The complement system may also interact with known risk factors of MS, including as Epstein Barr Virus (EBV) infection, and perpetuate the activation of CNS self-reactive B cell populations. With the mounting evidence for the involvement of complement in MS, the development of complement modulating therapies for this condition is appealing. Herein, we also reviewed the pharmacological complement inhibitors that have been tested in MS animal models as well as in clinical trials for other neurologic diseases. The potential use of these agents, such as the C5-binding antibody eculizumab in MS will require a detailed understanding of the role of the different complement effectors in this disease and the development of better CNS delivery strategies for these compounds.

Cumulative Roles for Epstein-Barr Virus, Human Endogenous Retroviruses, and Human Herpes Virus-6 in Driving an Inflammatory Cascade Underlying MS Pathogenesis

Roles for viral infections and aberrant immune responses in driving localized neuroinflammation and neurodegeneration in multiple sclerosis (MS) are the focus of intense research. Epstein-Barr virus (EBV), as a persistent and frequently reactivating virus with major immunogenic influences and a near 100% epidemiological association with MS, is considered to play a leading role in MS pathogenesis, triggering localized inflammation near or within the central nervous system (CNS). This triggering may occur directly via viral products (RNA and protein) and/or indirectly via antigenic mimicry involving B-cells, T-cells and cytokine-activated astrocytes and microglia cells damaging the myelin sheath of neurons. The genetic MS-risk factor HLA-DR2b (DRB1*1501β, DRA1*0101α) may contribute to aberrant EBV antigen-presentation and anti-EBV reactivity but also to mimicry-induced autoimmune responses characteristic of MS. A central role is proposed for inflammatory EBER1, EBV-miRNA and LMP1 containing exosomes secreted by viable reactivating EBV+ B-cells and repetitive release of EBNA1-DNA complexes from apoptotic EBV+ B-cells, forming reactive immune complexes with EBNA1-IgG and complement. This may be accompanied by cytokine- or EBV-induced expression of human endogenous retrovirus-W/-K (HERV-W/-K) elements and possibly by activation of human herpesvirus-6A (HHV-6A) in early-stage CNS lesions, each contributing to an inflammatory cascade causing the relapsing-remitting neuro-inflammatory and/or progressive features characteristic of MS. Elimination of EBV-carrying B-cells by antibody- and EBV-specific T-cell therapy may hold the promise of reducing EBV activity in the CNS, thereby limiting CNS inflammation, MS symptoms and possibly reversing disease. Other approaches targeting HHV-6 and HERV-W and limiting inflammatory kinase-signaling to treat MS are also being tested with promising results. This article presents an overview of the evidence that EBV, HHV-6, and HERV-W may have a pathogenic role in initiating and promoting MS and possible approaches to mitigate development of the disease.

Clinical risk factors and prognostic model for idiopathic inflammatory demyelinating diseases after haploidentical hematopoietic stem cell transplantation in patients with hematological malignancies

Idiopathic inflammatory demyelinating diseases (IIDDs) of the central nervous system (CNS) are rare but serious neurological complications of haploidentical hematopoietic stem cell transplantation (haplo-HSCT). However, the risk factors and a method to predict the prognosis of post-transplantation CNS IIDDs are not available. This retrospective study first reviewed data from 4532 patients who received haplo-HSCT during 2008-2019 in our center, and 184 patients (4.1%) with IIDDs after haplo-HSCT were identified. Grades II to IV acute graft-versus-host disease (aGVHD) (p < 0.001) and chronic GVHD (cGVHD) (p = 0.009) were identified as risk factors for developing IIDDs after haplo-HSCT. We then divided the 184 IIDD patients into a derivation cohort and validation cohort due to transplantation time to develop and validate a model for predicting the prognosis of IIDDs. In the multivariate analysis of the derivation cohort, four candidate predictors were entered into the final prognostic model: cytomegalovirus (CMV) infection, Epstein-Barr virus (EBV) infection, IgG synthesis (IgG-syn) and spinal cord lesions. The prognostic model had an area under the receiver operating characteristic curve of 0.864 (95% CI: 0.803-0.925) in the internal validation cohort and 0.871 (95% CI: 0.806-0.931) in the external validation cohort. The calibration plots showed a high agreement between the predicted and observed outcomes. Decision curve analysis indicated that IIDD patients could benefit from the clinical application of the prognostic model. The identification of IIDD patients after allo-HSCT who have a poor prognosis might allow timely treatment and improve patient survival and outcomes.

Crosstalk of Microorganisms and Immune Responses in Autoimmune Neuroinflammation: A Focus on Regulatory T Cells

Regulatory T cells (Tregs) are the major determinant of peripheral immune tolerance. Many Treg subsets have been described, however thymus-derived and peripherally induced Tregs remain the most important subpopulations. In multiple sclerosis, a prototypical autoimmune disorder of the central nervous system, Treg dysfunction is a pathogenic hallmark. In contrast, induction of Treg proliferation and enhancement of their function are central immune evasion mechanisms of infectious pathogens. In accordance, Treg expansion is compartmentalized to tissues with high viral replication and prolonged in chronic infections. In friend retrovirus infection, Treg expansion is mainly based on excessive interleukin-2 production by infected effector T cells. Moreover, pathogens seem also to enhance Treg functions as shown in human immunodeficiency virus infection, where Tregs express higher levels of effector molecules such as cytotoxic T-lymphocyte-associated protein 4, CD39 and cAMP and show increased suppressive capacity. Thus, insights into the molecular mechanisms by which intracellular pathogens alter Treg functions might aid to find new therapeutic approaches to target central nervous system autoimmunity. In this review, we summarize the current knowledge of the role of pathogens for Treg function in the context of autoimmune neuroinflammation. We discuss the mechanistic implications for future therapies and provide an outlook for new research directions.

Genetic, Environmental and Lifestyle Determinants of Accelerated Telomere Attrition as Contributors to Risk and Severity of Multiple Sclerosis

Telomeres are protective structures at the ends of linear chromosomes. Shortened telomere lengths (TL) are an indicator of premature biological aging and have been associated with a wide spectrum of disorders, including multiple sclerosis (MS). MS is a chronic inflammatory, demyelinating and neurodegenerative disease of the central nervous system. The exact cause of MS is still unclear. Here, we provide an overview of genetic, environmental and lifestyle factors that have been described to influence TL and to contribute to susceptibility to MS and possibly disease severity. We show that several early-life factors are linked to both reduced TL and higher risk of MS, e.g., adolescent obesity, lack of physical activity, smoking and vitamin D deficiency. This suggests that the mechanisms underlying the disease are connected to cellular aging and senescence promoted by increased inflammation and oxidative stress. Additional prospective research is needed to clearly define the extent to which lifestyle changes can slow down disease progression and prevent accelerated telomere loss in individual patients. It is also important to further elucidate the interactions between shared determinants of TL and MS. In future, cell type-specific studies and advanced TL measurement methods could help to better understand how telomeres may be causally involved in disease processes and to uncover novel opportunities for improved biomarkers and therapeutic interventions in MS.

Identification of Potential Inhibitors against Epstein-Barr Virus Nuclear Antigen 1 (EBNA1): An Insight from Docking and Molecular Dynamic Simulations

Epstein-Barr virus (EBV), a known tumorigenic virus, is associated with various neuropathies, including multiple sclerosis (MS). However, there is no anti-EBV FDA-approved drug available in the market. Our study targeted EBV protein EBV nuclear antigen 1 (EBNA1), crucial in virus replication and expressed in all the stages of viral latencies. This dimeric protein binds to an 18 bp palindromic DNA sequence and initiates the process of viral replication. We chose phytochemicals and FDA-approved MS drugs based on literature survey followed by their evaluation efficacies as anti-EBNA1 molecules. Molecular docking revealed FDA drugs ozanimod, siponimod, teriflunomide, and phytochemicals; emodin; protoapigenone; and EGCG bound to EBNA1 with high affinities. ADMET and Lipinski's rule analysis of the phytochemicals predicted favorable druggability. We supported our assessments of pocket druggability with molecular dynamics simulations and binding affinity predictions by the molecular mechanics generalized Born surface area (MM/GBSA) method. Our results establish a stable binding for siponimod and ozanimod with EBNA1 mainly via van der Waals interactions. We identified hot spot residues like I481', K477', L582', and K586' in the binding of ligands. In particular, K477' at the amino terminal of EBNA1 is known to establish interaction with two bases at the major groove of the DNA. Siponimod bound to EBNA1 engaging K477', thus plausibly making it unavailable for DNA interaction. Computational alanine scanning further supported the significant roles of K477', I481', and K586' in the binding of ligands with EBNA1. Conclusively, the compounds showed promising results to be used against EBNA1.

T cell composition and polygenic multiple sclerosis risk: A population-based study in children

Background and purpose

Patients with multiple sclerosis (MS) have altered T cell function and composition. Common genetic risk variants for MS affect proteins that function in the immune system. It is currently unclear to what extent T cell composition is affected by genetic risk factors for MS, and how this may precede a possible disease onset. Here, we aim to assess whether an MS polygenic risk score (PRS) is associated with an altered T cell composition in a large cohort of children from the general population.

Methods

We included genotyped participants from the population‐based Generation R study in whom immunophenotyping of blood T cells was performed at the age of 6 years. Analyses of variance were used to determine the impact of MS‐PRSs on total T cell numbers (n = 1261), CD4⁺ and CD8⁺ lineages, and subsets therein (n= 675). In addition, T‐cell‐specific PRSs were constructed based on functional pathway data.

Results

The MS‐PRS negatively correlated with CD8⁺ T cell frequencies (p = 2.92 × 10⁻³), which resulted in a positive association with CD4⁺/CD8⁺ T cell ratios (p = 8.27 × 10⁻⁹). These associations were mainly driven by two of 195 genome‐wide significant MS risk variants: the main genetic risk variant for MS, HLA‐DRB1*15:01 and an HLA‐B risk variant. We observed no significant associations for the T‐cell‐specific PRSs.

Conclusions

Our results suggest that MS‐associated genetic variants affect T cell composition during childhood in the general population.

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.

The Impact of SARS-CoV-2 Infection on the Development of Neurodegeneration in Multiple Sclerosis

The novel coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global challenge. Currently, there is some information on the consequences of COVID-19 infection in multiple sclerosis (MS) patients, as it is a newly discovered coronavirus, but its far-reaching effects on participation in neurodegenerative diseases seem to be significant. Recent cases reports showed that SARS-CoV-2 may be responsible for initiating the demyelination process in people who previously had no symptoms associated with any nervous system disorders. It is presently known that infection of SARS-CoV-2 evokes cytokine storm syndrome, which may be one of the factors leading to the acute cerebrovascular disease. One of the substantial problems is the coexistence of cerebrovascular disease and MS in an individual's life span. Epidemiological studies showed an enhanced risk of death rate from vascular disabilities in MS patients of approximately 30%. It has been demonstrated that patients with severe SARS-CoV-2 infection usually show increased levels of D-dimer, fibrinogen, C-reactive protein (CRP), and overactivation of blood platelets, which are essential elements of prothrombotic events. In this review, the latest knowledge gathered during an ongoing pandemic of SARS-CoV-2 infection on the neurodegeneration processes in MS is discussed.

Human Cytomegalovirus and Autoimmune Diseases: Where Are We?

Human cytomegalovirus (HCMV) is a ubiquitous double-stranded DNA virus belonging to the β-subgroup of the herpesvirus family. After the initial infection, the virus establishes latency in poorly differentiated myeloid precursors from where it can reactivate at later times to cause recurrences. In immunocompetent subjects, primary HCMV infection is usually asymptomatic, while in immunocompromised patients, HCMV infection can lead to severe, life-threatening diseases, whose clinical severity parallels the degree of immunosuppression. The existence of a strict interplay between HCMV and the immune system has led many to hypothesize that HCMV could also be involved in autoimmune diseases (ADs). Indeed, signs of active viral infection were later found in a variety of different ADs, such as rheumatological, neurological, enteric disorders, and metabolic diseases. In addition, HCMV infection has been frequently linked to increased production of autoantibodies, which play a driving role in AD progression, as observed in systemic lupus erythematosus (SLE) patients. Documented mechanisms of HCMV-associated autoimmunity include molecular mimicry, inflammation, and nonspecific B-cell activation. In this review, we summarize the available literature on the various ADs arising from or exacerbating upon HCMV infection, focusing on the potential role of HCMV-mediated immune activation at disease onset.

Herpesvirus Antibodies, Vitamin D and Short-Chain Fatty Acids: Their Correlation with Cell Subsets in Multiple Sclerosis Patients and Healthy Controls

Although the etiology of multiple sclerosis (MS) is still unknown, it is commonly accepted that environmental factors could contribute to the disease. The objective of this study was to analyze the humoral response to Epstein-Barr virus, human herpesvirus 6A/B and cytomegalovirus, and the levels of 25-hydroxyvitamin D (25(OH)D) and the three main short-chain fatty acids (SCFA), propionate (PA), butyrate (BA) and acetate (AA), in MS patients and healthy controls (HC) to understand how they could contribute to the pathogenesis of the disease. With this purpose, we analyzed the correlations among them and with different clinical variables and a wide panel of cell subsets. We found statistically significant differences for most of the environmental factors analyzed when we compared MS patients and HC, supporting their possible involvement in the disease. The strongest correlations with the clinical variables and the cell subsets analyzed were found for 25(OH)D and SCFAs levels. A correlation was also found between 25(OH)D and PA/AA ratio, and the interaction between these factors negatively correlated with interleukin 17 (IL-17)-producing CD4+ and CD8+ T cells in untreated MS patients. Therapies that simultaneously increase vitamin D levels and modify the proportion of SCFA could be evaluated in the future.

Increased frequency of canine distemper virus-specific antibodies in multiple sclerosis

BACKGROUND AND PURPOSE

Canine distemper virus (CDV) is a candidate agent in the etiology of multiple sclerosis (MS). Elevated anti-CDV levels were previously found in the sera from MS patients compared with controls. We now investigated whether there was an age-related association with the presence of antibodies specific to CDV-hemagglutinin (H) protein in MS.

METHODS

Sera from patients with MS, other neurological diseases, and inflammatory and/or autoimmune diseases, and healthy individuals were screened for anti-CDV in an ELISA using linear peptides of the CDV-H protein as antigen. Antibody levels to measles and varicella-zoster virus were measured and served as controls.

RESULTS

Analysis of the new cohort of MS patients and controls confirmed our initial finding of elevated anti-CDV-H levels in MS patients. An increase in measles but not varicella-zoster virus antibody levels was found in MS patients compared with healthy controls. Data from the new cohort of patients and controls were combined with data from the original study and analyzed with respect to age distribution of anti-CDV IgG. Mean CDV antibody levels were significantly elevated in each decade from 20 to 50 years of age in MS compared with healthy and disease controls. Antibody levels to measles virus were not consistently elevated during this age span. A striking relationship (p < .0001, odds ratio = 5.0) was observed between elevated anti-CDV-H levels and diagnosis of MS.

CONCLUSIONS

The finding that anti-CDV levels are elevated in MS patients of all ages provides substantial evidence of a strong association between elevated anti-CDV and MS.

Prognostication and contemporary management of clinically isolated syndrome

Clinically isolated syndrome (CIS) patients present with a single attack of inflammatory demyelination of the central nervous system. Recent advances in multiple sclerosis (MS) diagnostic criteria have expanded the number of CIS patients eligible for a diagnosis of MS at the onset of the disease, shrinking the prevalence of CIS. MS treatment options are rapidly expanding, which is driving the need to recognise MS at its earliest stages. In CIS patients, finding typical MS white matter lesions on the patient's MRI scan remains the most influential prognostic investigation for predicting subsequent diagnosis with MS. Additional imaging, cerebrospinal fluid and serum testing, information from the clinical history and genetic testing also contribute. For those subsequently diagnosed with MS, there is a wide spectrum of long-term clinical outcomes. Detailed assessment at the point of presentation with CIS provides fewer clues to calculate a personalised risk of long-term severe disability.Clinicians should select suitable CIS cases for steroid treatment to speed neurological recovery. Unfortunately, there are still no neuroprotection or remyelination strategies available. The use of MS disease modifying therapy for CIS varies among clinicians and national guidelines, suggesting a lack of robust evidence to guide practice. Clinicians should focus on confirming MS speedily and accurately with appropriate investigations. Diagnosis with CIS provides an opportune moment to promote a healthy lifestyle, in particular smoking cessation. Patients also need to understand the link between CIS and MS. This review provides clinicians an update on the contemporary evidence guiding prognostication and management of CIS.

Epstein Barr virus infection and immune defense related to HLA-DR15: consequences for multiple sclerosis

MS is a multifactorial disease in which a series of genetic and non‐genetic, environmental factors plays a role in its etiology. In particular, HLA class II alleles, mainly HLADRB1*15:01 (HLA‐DR15), increase the risk for this disease. Out of several environmental factors, and with regard to infections, EBV remains to be a strong candidate, and may synergize with HLA‐DR15 thus increasing the risk for MS. In this issue of the European Journal of Immunology, Zdimerova et al. present highly interesting experimental data using EBV infection in immune‐deficient mice engrafted with human immune cells, either HLA‐DR15⁺ or HLA‐DRB1*04:01 (HLA DR4), here after denoted as HLA‐DR15⁻. As a result of EBV infection, the viral load and CD8⁺ cell expansion were conspicuously higher in mice engrafted with HLA‐DR15⁺ compared to HLA‐DR15⁻ mice; and myelin basic protein specific T cells emerged in mice engrafted with HLA‐DR15 bearing cells. This study sheds light on how EBV and the class II DR15 haplotype may jointly predispose and synergize in the etiology of 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.

The association of Epstein-Barr virus infection with CXCR3+ B-cell development in multiple sclerosis: impact of immunotherapies

Epstein–Barr virus (EBV) infection of B cells is associated with increased multiple sclerosis (MS) susceptibility. Recently, we found that CXCR3‐expressing B cells preferentially infiltrate the CNS of MS patients. In chronic virus‐infected mice, these types of B cells are sustained and show increased antiviral responsiveness. How EBV persistence in B cells influences their development remains unclear. First, we analyzed ex vivo B‐cell subsets from MS patients who received autologous bone marrow transplantation (n = 9), which is often accompanied by EBV reactivation. The frequencies of nonclass‐switched and class‐switched memory B cells were reduced at 3–7 months, while only class‐switched B cells returned back to baseline at 24–36 months posttransplantation. At these time points, EBV DNA load positively correlated to the frequency of CXCR3⁺, and not CXCR4⁺ or CXCR5⁺, class‐switched B cells. Second, for CXCR3⁺ memory B cells trapped within the blood of MS patients treated with natalizumab (anti‐VLA‐4 antibody n = 15), latent EBV infection corresponded to enhanced in vitro formation of anti‐EBNA1 IgG‐secreting plasma cells under GC‐like conditions. These findings imply that EBV persistence in B cells potentiates brain‐homing and antibody‐producing CXCR3⁺ subsets in MS.

Attenuated immune control of Epstein-Barr virus in humanized mice is associated with the multiple sclerosis risk factor HLA-DR15

Immune responses to Epstein-Barr virus (EBV) infection synergize with the main genetic risk factor HLA-DRB1*15:01 (HLA-DR15) to increase the likelihood to develop the autoimmune disease multiple sclerosis (MS) at least sevenfold. In order to gain insights into this synergy, we investigated HLA-DR15 positive human immune compartments after reconstitution in immune-compromised mice (humanized mice) with and without EBV infection. We detected elevated activation of both CD4⁺ and CD8⁺ T cells in HLA-DR15 donor-reconstituted humanized mice at steady state, even when compared to immune compartments carrying HLA-DRB1*04:01 (HLA-DR4), which is associated with other autoimmune diseases. Increased CD8⁺ T cell expansion and activation was also observed in HLA-DR15 donor-reconstituted humanized mice after EBV infection. Despite this higher immune activation, EBV viral loads were less well controlled in the context of HLA-DR15. Indeed, HLA-DR15-restricted CD4⁺ T cell clones recognized EBV-transformed B cell lines less efficiently and demonstrated cross-reactivity toward allogeneic target cells and one MS autoantigen. These findings suggest that EBV as one of the main environmental risk factors and HLA-DR15 as the main genetic risk factor for MS synergize by priming hyperreactive T-cell compartments, which then control the viral infection less efficiently and contain cross-reactive CD4⁺ T cell clones.

Microglia depletion exacerbates demyelination and impairs remyelination in a neurotropic coronavirus infection

Microglia are considered both pathogenic and protective during recovery from demyelination, but their precise role remains ill defined. Here, using an inhibitor of colony stimulating factor 1 receptor (CSF1R), PLX5622, and mice infected with a neurotropic coronavirus (mouse hepatitis virus [MHV], strain JHMV), we show that depletion of microglia during the time of JHMV clearance resulted in impaired myelin repair and prolonged clinical disease without affecting the kinetics of virus clearance. Microglia were required only during the early stages of remyelination. Notably, large deposits of extracellular vesiculated myelin and cellular debris were detected in the spinal cords of PLX5622-treated and not control mice, which correlated with decreased numbers of oligodendrocytes in demyelinating lesions in drug-treated mice. Furthermore, gene expression analyses demonstrated differential expression of genes involved in myelin debris clearance, lipid and cholesterol recycling, and promotion of oligodendrocyte function. The results also demonstrate that microglial functions affected by depletion could not be compensated by infiltrating macrophages. Together, these results demonstrate that microglia play key roles in debris clearance and in the initiation of remyelination following infection with a neurotropic coronavirus but are not necessary during later stages of remyelination.

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

Recombinant Epstein-Barr virus glycoprotein 350 as a serological antigen

Epstein-Barr virus (EBV) glycoprotein 350 (gp350) is the most abundant glycoprotein expressed on the EBV envelope, the major target for neutralizing antibodies and also essential for virion attachment to B lymphocytes. Several studies have addressed EBV gp350 as a vaccine candidate, but less commonly as a potential antigen for serological assays. The aim of the current study was to develop a diagnostic tool to quantify EBV gp350-specific IgG in previously EBV-infected individuals. A construct encoding the extracellular domain of EBV gp350 (amino acid (aa) 1-860) was developed for expression in Chinese hamster ovary cells. Serum samples (n = 360) with known IgG serostatus against viral capsid antigen (VCA) and Epstein-Barr nuclear antigen 1 (EBNA1) were divided into three groups based on the differences in their serostatus: VCA + EBNA1+ (n = 120), VCA + EBNA1- (n = 120) and VCA-EBNA1- (n = 120). The samples were analyzed by indirect ELISA using recombinant EBV gp350 aa 1-860 as antigen. A clear majority, 108 of the 120 VCA + EBNA1+ samples, had detectable EBV gp350-specific IgG. Of the 120 VCA + EBNA1- samples, 79 had detectable EBV gp350-specific IgG. Only 2 of the 120 VCA-EBNA1- samples had detectable EBV gp350-specific IgG. The results reported here show that use of the EBV gp350 aa 1-860 ELISA can serve as a sensitive method for EBV-specific IgG detection in serum samples.

B and T Cells Driving Multiple Sclerosis: Identity, Mechanisms and Potential Triggers

Historically, multiple sclerosis (MS) has been viewed as being primarily driven by T cells. However, the effective use of anti-CD20 treatment now also reveals an important role for B cells in MS patients. The results from this treatment put forward T-cell activation rather than antibody production by B cells as a driving force behind MS. The main question of how their interaction provokes both B and T cells to infiltrate the CNS and cause local pathology remains to be answered. In this review, we highlight key pathogenic events involving B and T cells that most likely contribute to the pathogenesis of MS. These include (1) peripheral escape of B cells from T cell-mediated control, (2) interaction of pathogenic B and T cells in secondary lymph nodes, and (3) reactivation of B and T cells accumulating in the CNS. We will focus on the functional programs of CNS-infiltrating lymphocyte subsets in MS patients and discuss how these are defined by mechanisms such as antigen presentation, co-stimulation and cytokine production in the periphery. Furthermore, the potential impact of genetic variants and viral triggers on candidate subsets will be debated in the context of MS.

What do we currently know about the clinically isolated syndrome suggestive of multiple sclerosis? An update

Multiple sclerosis (MS) is a chronic, demyelinating, not fully understood disease of the central nervous system. The first demyelinating clinical episode is called clinically isolated syndrome (CIS) suggestive of MS. Although the most common manifestations of CIS are long tracts dysfunction and unilateral optic neuritis, it can also include isolated brainstem syndromes, cerebellar involvement, and polysymptomatic clinical image. Recently, the frequency of CIS diagnosis has decreased due to the more sensitive and less specific 2017 McDonald criteria compared with the revisions from 2010. Not all patients with CIS develop MS. The risk of conversion can be estimated based on many predictive factors including epidemiological, ethnical, clinical, biochemical, radiological, immunogenetic, and other markers. The management of CIS is nowadays widely discussed among clinicians and neuroscientists. To date, interferons, glatiramer acetate, teriflunomide, cladribine, and some other agents have been evaluated in randomized, placebo-controlled, double-blind studies relying on large groups of patients with the first demyelinating event. All of these drugs were shown to have beneficial effects in patients with CIS and might be used routinely in the future. The goal of this article is to explore the most relevant topics regarding CIS as well as to provide the most recent information in the field. The review presents CIS definition, classification, clinical image, predictive factors, and management. What is more, this is one of very few reviews summarizing the topic in the light of the 2017 McDonald criteria.

Vitamin D, smoking, EBV, and long-term cognitive performance in MS: 11-year follow-up of BENEFIT

OBJECTIVE

To investigate whether vitamin D, smoking, and anti-Epstein-Barr virus (EBV) antibody concentrations predict long-term cognitive status and neuroaxonal injury in multiple sclerosis (MS).

METHODS

This study was conducted among 278 patients with clinically isolated syndrome who participated in the clinical trial BENEFIT (Betaferon/Betaseron in Newly Emerging Multiple Sclerosis for Initial Treatment) and completed the 11-year assessment (BENEFIT-11). We measured serum 25-hydroxyvitamin-D (25(OH)D), cotinine (smoking biomarker), and anti-Epstein-Barr virus nuclear antigen 1 (EBNA-1) immunoglobulin G (IgG) at baseline and at months 6, 12, and 24 and examined whether these biomarkers contributed to predict Paced Auditory Serial Addition Test (PASAT)-3 scores and serum neurofilament light chain (NfL) concentrations at 11 years. Linear and logistic regression models were adjusted for sex, baseline age, treatment allocation, steroid treatment, multifocal symptoms, T2 lesions, and body mass index.

RESULTS

Higher vitamin D predicted better, whereas smoking predicted worse cognitive performance. A 50-nmol/L higher mean 25(OH)D in the first 2 years was related to 65% lower odds of poorer PASAT performance at year 11 (95% confidence intervals [95% CIs]: 0.14-0.89). Standardized PASAT scores were lower in smokers and heavy smokers than nonsmokers (p _trend = 0.026). Baseline anti-EBNA-1 IgG levels did not predict cognitive performance (p _trend = 0.88). Associations with NfL concentrations at year 11 corroborated these findings-a 50-nmol/L higher mean 25(OH)D in the first 2 years was associated with 20% lower NfL (95% CI: -36% to 0%), whereas smokers had 20% higher NfL levels than nonsmokers (95% CI: 2%-40%). Anti-EBNA-1 antibodies were not associated with NfL.

CONCLUSIONS

Lower vitamin D and smoking after clinical onset predicted worse long-term cognitive function and neuronal integrity in patients with MS.