Viruses and multiple sclerosis

HERPES SIMPLEX VIRUS-1 SUSCEPTIBILITY AS A RISK FACTOR FOR SEPSIS, WITH CYTOMEGALOVIRUS SUSCEPTIBILITY ELEVATING SEVERITY: INSIGHTS FROM A BIDIRECTIONAL MENDELIAN RANDOMIZATION STUDY

ABSTRACT

Objective: We conducted a two-sample bidirectional Mendelian randomization (MR) study to investigate the causal relationships between herpes viruses and sepsis. Methods: Publicly available genome-wide association study data were used. Four viruses, HSV-1, HSV-2, EBV, and CMV, were selected, with serum positivity and levels of antibody in serum as the herpes virus data. Results: In forward MR, susceptibility to HSV-1 was a risk factor for sepsis. The susceptibility to CMV showed a severity-dependent effect on sepsis and was a risk factor for the 28-day mortality from sepsis, and was also a risk factor for 28-day sepsis mortality in critical care admission. The EBV EA-D antibody level after EBV infection was a protective factor for 28-day sepsis mortality in critical care admission, and CMV pp28 antibody level was a risk factor for 28-day sepsis mortality in critical care admission. No statistically significant causal relationships between HSV-2 and sepsis were found. No exposures having statistically significant association with sepsis critical care admission as an outcome were found. In reverse MR, the sepsis critical care admission group manifested a decrease in CMV pp52 antibody levels. No causal relationships with statistical significance between sepsis exposure and other herpes virus outcomes were found. Conclusion: Our study identifies HSV-1 susceptibility as a sepsis risk, with CMV susceptibility elevating severity. Varied effects of EBV and CMV antibodies on sepsis severity are noted. Severe sepsis results in a decline in CMV antibody levels. Our results help prognostic and predictive enrichment and offer valuable information for precision sepsis treatment.

Twenty Years of Subcutaneous Interferon-Beta-1a for Multiple Sclerosis: Contemporary Perspectives

Multiple sclerosis (MS) is a chronic, progressive, inflammatory disorder of the central nervous system. Relapsing-remitting MS (RRMS), the most common form of the disease, is characterized by transient neurological dysfunction with concurrent accumulation of disability. Over the past three decades, disease-modifying therapies (DMTs) capable of reducing the frequency of relapses and slowing disability worsening have been studied and approved for use in patients with RRMS. The first DMTs were interferon-betas (IFN-βs), which were approved in the 1990s. Among them was IFN-β-1a for subcutaneous (sc) injection (Rebif®), which was approved for the treatment of MS in Europe and Canada in 1998 and in the USA in 2002. Twenty years of clinical data and experience have supported the efficacy and safety of IFN-β-1a sc in the treatment of RRMS, including pivotal trials, real-world data, and extension studies lasting up to 15 years past initial treatment. Today, IFN-β-1a sc remains an important therapeutic option in clinical use, especially around pregnancy planning and lactation, and may also be considered for aging patients, in which MS activity declines and long-term immunosuppression associated with some alternative therapies is a concern. In addition, IFN-β-1a sc is used as a comparator in many clinical studies and provides a framework for research into the mechanisms by which MS begins and progresses.

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.

Expression profiling of cerebrospinal fluid identifies dysregulated antiviral mechanisms in multiple sclerosis

Despite the overwhelming evidence that multiple sclerosis is an autoimmune disease, relatively little is known about the precise nature of the immune dysregulation underlying the development of the disease. Reasoning that the CSF from patients might be enriched for cells relevant in pathogenesis, we have completed a high-resolution single-cell analysis of 96 732 CSF cells collected from 33 patients with multiple sclerosis (n = 48 675) and 48 patients with other neurological diseases (n = 48 057). Completing comprehensive cell type annotation, we identified a rare population of CD8+ T cells, characterized by the upregulation of inhibitory receptors, increased in patients with multiple sclerosis. Applying a Multi-Omics Factor Analysis to these single-cell data further revealed that activity in pathways responsible for controlling inflammatory and type 1 interferon responses are altered in multiple sclerosis in both T cells and myeloid cells. We also undertook a systematic search for expression quantitative trait loci in the CSF cells. Of particular interest were two expression quantitative trait loci in CD8+ T cells that were fine mapped to multiple sclerosis susceptibility variants in the viral control genes ZC3HAV1 (rs10271373) and IFITM2 (rs1059091). Further analysis suggests that these associations likely reflect genetic effects on RNA splicing and cell-type specific gene expression respectively. Collectively, our study suggests that alterations in viral control mechanisms might be important in the development of multiple sclerosis.

Human herpesvirus 6A and axonal injury before the clinical onset of multiple sclerosis

Recent research indicates that multiple sclerosis is preceded by a prodromal phase with elevated levels of serum neurofilament light chain (sNfL), a marker of axonal injury. The effect of environmental risk factors on the extent of axonal injury during this prodrome is unknown. Human herpesvirus 6A (HHV-6A) is associated with an increased risk of developing multiple sclerosis. The objective of this study was to determine if HHV-6A serostatus is associated with the level of sNfL in the multiple sclerosis prodrome, which would support a causative role of HHV-6A. A nested case-control study was performed by crosslinking multiple sclerosis registries with Swedish biobanks. Individuals with biobank samples collected before the clinical onset of multiple sclerosis were included as cases. Controls without multiple sclerosis were randomly selected, matched for biobank, sex, sampling date and age. Serostatus of HHV-6A and Epstein-Barr virus was analysed with a bead-based multiplex assay. The concentration of sNfL was analysed with single molecule array technology. The association between HHV-6A serology and sNfL was assessed by stratified t-tests and linear regressions, adjusted for Epstein-Barr virus serostatus and sampling age. Within-pair ratios of HHV-6A seroreactivity and sNfL were calculated for each case and its matched control. To assess the temporal relationship between HHV-6A antibodies and sNfL, these ratios were plotted against the time to the clinical onset of multiple sclerosis and compared using locally estimated scatterplot smoothing regressions with 95% confidence intervals (CI). Samples from 519 matched case-control pairs were included. In cases, seropositivity of HHV-6A was significantly associated with the level of sNfL (+11%, 95% CI 0.2-24%, P = 0.045) and most pronounced in the younger half of the cases (+24%, 95% CI 6-45%, P = 0.007). No such associations were observed among the controls. Increasing seroreactivity against HHV-6A was detectable before the rise of sNfL (significant within-pair ratios from 13.6 years versus 6.6 years before the clinical onset of multiple sclerosis). In this study, we describe the association between HHV-6A antibodies and the degree of axonal injury in the multiple sclerosis prodrome. The findings indicate that elevated HHV-6A antibodies both precede and are associated with a higher degree of axonal injury, supporting the hypothesis that HHV-6A infection may contribute to multiple sclerosis development in a proportion of cases.

The effect of COVID-19 on Multiple Sclerosis relapse: A systematic review and meta-analysis

BACKGROUND

Multiple Sclerosis (MS) is a chronic autoimmune disease, affecting over 2.5 million people worldwide. There has been growing concern about the impact of COVID-19 on the clinical course of MS. However, these findings remain controversial, and there is a lack of high-quality evidence to establish the relationship between COVID-19 and MS.

METHODS

A comprehensive search was done to identify relevant studies reporting relapse rate in patients with MS (pwMS), those comparing the relapse rate of COVID-19 pwMS and MS controls, and studies investigating the effect of COVID-19 on relapse rate of pwMS. The results were presented as proportion of COVID-19 pwMS experiencing relapse and odds ratio determining the impact of COVID-19 on relapse rate.

RESULTS

Fourteen studies were included in the analyses. The proportion of COVID-19 positive pwMS with relapse was 7.71 per 100 cases (95 % confidence interval, CI: 4.41-13.89, I2=96 %). Quantitative evaluation of studies with pwMS without COVID-19 did not demonstrate a statistically significant difference in relapse rate of patients with COVID-19 (OR: 0.75, 95 %CI: 0.44-1.29, I2= 54 %). Subgroup and sensitivity analyses did not alter the lack of significance of association between COVID-19 and MS relapse. Sensitivity analysis excluding the outlying study was largely in favor of no difference between the groups (OR:1.00, 95 %CI: 0.72-1.38, I2=34 %) CONCLUSION: The results of this review does not suggest that COVID-19 influences the relapse rate in pwMS. While the findings alleviate the concerns regarding the co-occurrence of the diseases, further studies are needed to investigate the effects of confounding factors.

Negative association between multiple sclerosis immunogenetic profile and in silico immunogenicities of 12 viruses

Human Leukocyte Antigen (HLA) is involved in both multiple sclerosis (MS) and immune response to viruses. Here we investigated the virus-HLA immunogenicity (V-HLA) of 12 viruses implicated in MS with respect to 17 HLA Class I alleles positively associated to MS prevalence in 14 European countries. Overall, higher V-HLA immunogenicity was associated with smaller MS-HLA effect, with human herpes virus 3 (HHV3), JC human polyoma virus (JCV), HHV1, HHV4, HHV7, HHV5 showing the strongest association, followed by HHV8, HHV6A, and HHV6B (moderate association), and human endogenous retrovirus (HERV-W), HHV2, and human papilloma virus (HPV) (weakest association). These findings suggest that viruses with proteins of high HLA immunogenicity are eliminated more effectively and, consequently, less likely to be involved in MS.

Antibody Cross-Reactivity in Auto-Immune Diseases

Autoimmunity is defined by the presence of antibodies and/or T cells directed against self-components. Although of unknown etiology, autoimmunity commonly is associated with environmental factors such as infections, which have been reported to increase the risk of developing autoimmune diseases. Occasionally, similarities between infectious non-self and self-tissue antigens may contribute to immunological cross-reactivity in autoimmune diseases. These reactions may be interpreted as molecular mimicry, which describes cross-reactivity between foreign pathogens and self-antigens that have been reported to cause tissue damage and to contribute to the development of autoimmunity. By focusing on the nature of antibodies, cross-reactivity in general, and antibody-antigen interactions, this review aims to characterize the nature of potential cross-reactive immune reactions between infectious non-self and self-tissue antigens which may be associated with autoimmunity but may not actually be the cause of disease onset.

Environmental Influences on Risk and Disease Course in Pediatric Multiple Sclerosis

Pediatric multiple sclerosis (MS) accounts for 3%-10% of all patients diagnosed with MS. Complex interplay between environmental factors impacts the risk for MS and may also affect disease course. Many of these environmental factors are shared with adult-onset MS. However, children with MS are in closer temporal proximity to the biological onset of MS and have less confounding environmental exposures than their adult counterparts. Environmental factors that contribute to MS risk include: geographical latitude, viral exposures, obesity, vitamin deficiencies, smoking, air pollution, perinatal factors, gut microbiome, and diet. More recently, research efforts have shifted to studying the impact of these risk determinants on the clinical course of MS. In this article we will examine relevant environmental risk determinants of pediatric MS and review the current knowledge on how these factors may contribute to pediatric MS disease evolution.

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

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

Are Measles-Mumps-Rubella (MMR) Antibodies Friends or Foes for Covid-19 Disease?

Many factors have been implicated in the pathogenesis and severity of COVID-19 pandemic. A wide variation in the susceptibility for SARS-CoV-2 infection among different population, gender and age has been observed. Multiple studies investigated the relationship between the antibody's titre of previously vaccinated individuals and the susceptibility of coronavirus infection, to find a rapid effective therapy for this pandemic. This study focused on the association between measles-mumps-rubella (MMR) antibodies titre and the severity of COVID-19 infection. We aimed to investigate the correlation between the antibody's titre of MMR and the SARS-CoV-2 infection susceptibility and disease severity, in a cohort of COVID-19 Egyptian patients, compared to a control group. MMR antibody titre was measured using enzyme Linked Immune Sorbent Assay; (ELISA) for 136 COVID-19 patients and 44 healthy individuals, as control group. There were high levels of measles and mumps antibodies titer in the deteriorating cases, which could not protect from SARS-CoV-2 infection. However, the rubella antibodies might protect from SARS-CoV-2 infection, but once the infection occurs, it may aggravate the risk of case deterioration. MMR antibodies could be used as a guideline for COVID-19 symptom-severity and, in turn, may be considered as an economic prognostic marker used for early protection from multiple autoimmune organ failure.

Alzheimer's disease and multiple sclerosis: a possible connection through the viral demyelinating neurodegenerative trigger (vDENT)

Alzheimer's disease (AD) and multiple sclerosis (MS) are two CNS disorders affecting millions of people, for which no cure is available. AD is usually diagnosed in individuals age 65 and older and manifests with accumulation of beta amyloid in the brain. MS, a demyelinating disorder, is most commonly diagnosed in its relapsing-remitting (RRMS) form in young adults (age 20-40). The lack of success in a number of recent clinical trials of immune- or amyloid-targeting therapeutics emphasizes our incomplete understanding of their etiology and pathogenesis. Evidence is accumulating that infectious agents such as viruses may contribute either directly or indirectly. With the emerging recognition that demyelination plays a role in risk and progression of AD, we propose that MS and AD are connected by sharing a common environmental factor (a viral infection such as HSV-1) and pathology (demyelination). In the viral DEmyelinating Neurodegenerative Trigger (vDENT) model of AD and MS, the initial demyelinating viral (e.g., HSV-1) infection provokes the first episode of demyelination that occurs early in life, with subsequent virus reactivations/demyelination and associated immune/inflammatory attacks resulting in RRMS. The accumulating damage and/or virus progression deeper into CNS leads to amyloid dysfunction, which, combined with the inherent age-related defects in remyelination, propensity for autoimmunity, and increased blood-brain barrier permeability, leads to the development of AD dementia later in life. Preventing or diminishing vDENT event(s) early in life, thus, may have a dual benefit of slowing down the progression of MS and reducing incidence of AD at an older age.

No Increased Detection of Nucleic Acids of CNS-related Viruses in the Brains of Patients with Schizophrenia, Bipolar Disorder, and Autism Spectrum Disorder

BACKGROUND AND HYPOTHESIS

Viral infections are increasingly recognized in the etiology of psychiatric disorders based on epidemiological and serological studies. Few studies have analyzed viruses directly within the brain and no comprehensive investigation of viral infection within diseased brains has been completed. This study aims to determine whether viral infection in brain tissues is a risk factor for 3 major psychiatric disorders, including schizophrenia, bipolar disorder, and autism spectrum disorder.

STUDY DESIGN

This study directly evaluated the presence of viral DNA or RNA in 1569 brains of patients and controls using whole-genome sequencing and RNA sequencing data with 4 independent cohorts. The PathSeq tool was used to identify known human viruses in the genome and transcriptome of patients and controls.

STUDY RESULTS

A variety of DNA and RNA viruses related to the central nervous system were detected in the brains of patients with major psychiatric disorders, including viruses belonging to Herpesviridae, Polyomaviridae, Retroviridae, Flaviviridae, Parvoviridae, and Adenoviridae. However, no consistent significant differences were found between patients and controls in terms of types and amount of virus detected at both DNA and RNA levels.

CONCLUSIONS

The findings of this study do not suggest an association between viral infection in postmortem brains and major psychiatric disorders.

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.

Role of Innate Interferon Responses at the Ocular Surface in Herpes Simplex Virus-1-Induced Herpetic Stromal Keratitis

Herpes simplex virus type 1 (HSV-1) is a highly successful pathogen that primarily infects epithelial cells of the orofacial mucosa. After initial lytic replication, HSV-1 enters sensory neurons and undergoes lifelong latency in the trigeminal ganglion (TG). Reactivation from latency occurs throughout the host’s life and is more common in people with a compromised immune system. HSV-1 causes various diseases depending on the site of lytic HSV-1 replication. These include herpes labialis, herpetic stromal keratitis (HSK), meningitis, and herpes simplex encephalitis (HSE). HSK is an immunopathological condition and is usually the consequence of HSV-1 reactivation, anterograde transport to the corneal surface, lytic replication in the epithelial cells, and activation of the host’s innate and adaptive immune responses in the cornea. HSV-1 is recognized by cell surface, endosomal, and cytoplasmic pattern recognition receptors (PRRs) and activates innate immune responses that include interferons (IFNs), chemokine and cytokine production, as well as the recruitment of inflammatory cells to the site of replication. In the cornea, HSV-1 replication promotes type I (IFN-α/β) and type III (IFN-λ) IFN production. This review summarizes our current understanding of HSV-1 recognition by PRRs and innate IFN-mediated antiviral immunity during HSV-1 infection of the cornea. We also discuss the immunopathogenesis of HSK, current HSK therapeutics and challenges, proposed experimental approaches, and benefits of promoting local IFN-λ responses.

Persistent SARS-CoV-2 Infection, EBV, HHV-6 and Other Factors May Contribute to Inflammation and Autoimmunity in Long COVID

A novel syndrome called long-haul COVID or long COVID is increasingly recognized in a significant percentage of individuals within a few months after infection with SARS-CoV-2. This disorder is characterized by a wide range of persisting, returning or even new but related symptoms that involve different tissues and organs, including respiratory, cardiac, vascular, gastrointestinal, musculo-skeletal, neurological, endocrine and systemic. Some overlapping symptomatologies exist between long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Very much like with long ME/CFS, infections with herpes family viruses, immune dysregulation, and the persistence of inflammation have been reported as the most common pattern for the development of long COVID. This review describes several factors and determinants of long COVID that have been proposed, elaborating mainly on viral persistence, reactivation of latent viruses such as Epstein-Barr virus and human herpesvirus 6 which are also associated with the pathology of ME/CFS, viral superantigen activation of the immune system, disturbance in the gut microbiome, and multiple tissue damage and autoimmunity. Based on these factors, we propose diagnostic strategies such as the measurement of IgG and IgM antibodies against SARS-CoV-2, EBV, HHV-6, viral superantigens, gut microbiota, and biomarkers of autoimmunity to better understand and manage this multi-factorial disorder that continues to affect millions of people in the world.

[Gut microbiota in patients with relapsing-remitting multiple sclerosis]

Microorganisms in human life play a huge role: in particular, those that coexist with the host organism, inhabiting the skin, upper respiratory tract, external genitalia and especially the digestive tract. The intestinal microbiota, including bacteriome, mycobiome and virome, not only takes part in the digestion process, but also provides the synthesis of a number of vitamins. The intestinal microbiome also serves as the basis for a system of extensive bidirectional neuroendocrine pathways that connect microbiota with various regions of the central nervous system, the hypothalamic-pituitary-adrenal system, and the peripheral parts of the autonomic nervous system. This system of connections has got the name of gut-brain axis and has attracted close attention of scientists over the past two decades, since a targeted impact on the intestinal flora is potentially capable of changing the nature of nervous system regulatory influences on the whole body. It is especially important to study patterns of functioning of the gut-brain axis in patients with the nervous system pathology, namely neurodegenerative and demyelinating diseases. Methods for their treatment continue to improve, and perhaps the correction of the gut microbiotic composition will serve as an additional therapeutic approach. The review article describes current views on the role of the intestinal microbiota, provides the latest data on the composition of bacteriome, mycobiome, and virome in patients with relapsing-remitting multiple sclerosis.

The Development of the Combination Drug Leukovir® Tablets for the Treatment of Multiple Sclerosis: A Comprehensive Review

The review is devoted to the development and study of the drug Leukovir® (cladribine+ ribavirin) and its use in the treatment of relapsing-remitting and secondary progressive forms of multiple sclerosis, a chronic neurodegenerative disease aiming the risk reduction of relapse and progression of a disability. In clinical trials Leukovir® has proved to be efficient by up to 56 weeks for the treatment of relapsing-remitting and secondary progressive forms of multiple sclerosis. The drug is registered in the Republic of Belarus. The efficacy, safety and tolerability profile of the drug Leukovir® suggests that it is well suited for disease-modifying therapy of multiple sclerosis. Patients require four 35-day courses of treatment, each consisting of seven days of treatment followed by a break of 28 days. The use of Leukovir® has contributed to the suppression of inflammatory process activity according to MRI data and stabilization of the clinical condition. It has reduced the number of relapses in patients with relapsing-remitting and secondary-progressive forms of multiple sclerosis.

Viral-induced neuroinflammation: Different mechanisms converging to similar exacerbated glial responses

There is increasing evidence that viral infections are the source/origin of various types of encephalitis, encephalomyelitis, and other neurological and cognitive disorders. While the involvement of certain viruses, such as the Nipah virus and measles virus, is known, the mechanisms of neural invasion and the factors that trigger intense immune reactions are not fully understood. Based on recent publications, this review discusses the role of the immune response, interactions between viruses and glial cells, and cytokine mediators in the development of inflammatory diseases in the central nervous system. It also highlights the significant gaps in knowledge regarding these mechanisms.

Analysis of herpesvirus infection and genome single nucleotide polymorphism risk factors in multiple sclerosis, Volga federal district, Russia

Multiple sclerosis (MS) is a heterogeneous disease where herpesvirus infection and genetic predisposition are identified as the most consistent risk factors. Serum and blood samples were collected from 151 MS and 70 controls and used to analyze circulating antibodies for, and DNA of, Epstein Barr virus (EBV), human cytomegalovirus (HCMV), human herpes virus 6 (HHV6), and varicella zoster virus (VZV). The frequency of selected single nucleotide polymorphisms (SNPs) in MS and controls were studied. Herpesvirus DNA in blood samples were analyzed using qPCR. Anti-herpesvirus antibodies were detected by ELISA. SNPs were analyzed by the allele-specific PCR. For statistical analysis, Fisher exact test, odds ratio and Kruskall-Wallis test were used; p<0.05 values were considered as significant. We have found an association between circulating anti-HHV6 antibodies and MS diagnosis. We also confirmed higher frequency of A and C alleles in rs2300747 and rs12044852 of CD58 gene and G allele in rs929230 of CD6 gene in MS as compared to controls. Fatigue symptom was linked to AC and AA genotype in rs12044852 of CD58 gene. An interesting observation was finding higher frequency of GG genotype in rs12722489 of IL2RA and T allele in rs1535045 of CD40 genes in patient having anti-HHV6 antibodies. A link was found between having anti-VZV antibodies in MS and CC genotype in rs1883832 of CD40 gene.

The Role of Exposomes in the Pathophysiology of Autoimmune Diseases II: Pathogens

In our continuing examination of the role of exposomes in autoimmune disease, we use this review to focus on pathogens. Infections are major contributors to the pathophysiology of autoimmune diseases through various mechanisms, foremost being molecular mimicry, when the structural similarity between the pathogen and a human tissue antigen leads to autoimmune reactivity and even autoimmune disease. The three best examples of this are oral pathogens, SARS-CoV-2, and the herpesviruses. Oral pathogens reach the gut, disturb the microbiota, increase gut permeability, cause local inflammation, and generate autoantigens, leading to systemic inflammation, multiple autoimmune reactivities, and systemic autoimmunity. The COVID-19 pandemic put the spotlight on SARS-CoV-2, which has been called “the autoimmune virus.” We explore in detail the evidence supporting this. We also describe how viruses, in particular herpesviruses, have a role in the induction of many different autoimmune diseases, detailing the various mechanisms involved. Lastly, we discuss the microbiome and the beneficial microbiota that populate it. We look at the role of the gut microbiome in autoimmune disorders, because of its role in regulating the immune system. Dysbiosis of the microbiota in the gut microbiome can lead to multiple autoimmune disorders. We conclude that understanding the precise roles and relationships shared by all these factors that comprise the exposome and identifying early events and root causes of these disorders can help us to develop more targeted therapeutic protocols for the management of this worldwide epidemic of autoimmunity.

Tissue-resident memory CD8+ T cells cooperate with CD4+ T cells to drive compartmentalized immunopathology in the CNS

In chronic inflammatory diseases of the central nervous system (CNS), immune cells persisting behind the blood-brain barrier are supposed to promulgate local tissue destruction. The drivers of such compartmentalized inflammation remain unclear, but tissue-resident memory T cells (T_RM) represent a potentially important cellular player in this process. Here, we investigated whether resting CD8⁺ T_RM persisting after cleared infection with attenuated lymphocytic choriomeningitis virus (LCMV) can initiate immune responses directed against cognate self-antigen in the CNS. We demonstrated that time-delayed conditional expression of the LCMV glycoprotein as neo-self-antigen by glia cells reactivated CD8⁺ T_RM. Subsequently, CD8⁺ T_RM expanded and initiated CNS inflammation and immunopathology in an organ-autonomous manner independently of circulating CD8⁺ T cells. However, in the absence of CD4⁺ T cells, TCF-1⁺ CD8⁺ T_RM failed to expand and differentiate into terminal effectors. Similarly, in human demyelinating CNS autoimmune lesions, we found CD8⁺ T cells expressing TCF-1 that predominantly exhibited a T_RM-like phenotype. Together, our study provides evidence for CD8⁺ T_RM-driven CNS immunopathology and sheds light on why inflammatory processes may evade current immunomodulatory treatments in chronic autoimmune CNS conditions.

Coronaviruses and their relationship with multiple sclerosis: is the prevalence of multiple sclerosis going to increase after the Covid-19 pandemia?

The purpose of this review is to examine whether there is a possible (etiological/triggering) relationship between infection with various Coronaviruses, including Severe Acute Respiratory Syndrome-related Coronavirus-2 (SARS-CoV-2), the virus responsible for the Coronavirus disease-19 (Covid-19) pandemia, and Multiple Sclerosis (MS), and whether an increase of the prevalence of MS after the current Covid-19 pandemia should be expected, examining new and preexisting data. Although the exact pathogenesis of MS remains unknown, environmental agents seem to greatly influence the onset of the disease, with viruses being the most popular candidate. Existing data support this possible etiological relationship between viruses and MS, and experimental studies show that Coronaviruses can actually induce an MS-like demyelinating disease in animal models. Findings in MS patients could also be compatible with this coronaviral MS hypothesis. More importantly, current data from the Covid-19 pandemia show that SARS-CoV-2 can trigger autoimmunity and possibly induce autoimmune diseases, in the Central Nervous System as well, strengthening the viral hypothesis of MS. If we accept that Coronaviruses can induce MS, it is reasonable to expect an increase in the prevalence of MS after the Covid-19 pandemia. This knowledge is of great importance in order to protect the aging groups that are more vulnerable against autoimmune diseases and MS specifically, and to establish proper vaccination and health policies.

Non-infectious mechanisms of neurological damage due to infection

Infections of the nervous system is a growing aspect of clinical neurology. Accumulating knowledge in early diagnosis, course, therapy and prognosis is enlarging the clinical tools required for effective therapy. Of special importance is the ability to differentiate between proper infections, where anti-microbial agents, when available, should be introduced and used and post infectious conditions where therapy is mainly directed against the host immune system. The two conditions sometimes overlap, a situation that requires the ability to combine clinical skills with the use of laboratory tools such as polymerase chain reaction (PCR), serology, and antigenic detection. In the era of the SARS-CoV-2 pandemic, the need to make this distinction is emphasized as correct diagnosis of post infectious conditions and expedited therapy is important and sometimes lifesaving. We here attempt to present several infectious agents and their possible indirect damage to the nervous system causing in some cases significant neurological deficits. We try to limit our focus on those mechanisms which do not involve the direct tissue damage by the infectious agents but rather are connected to para- and post-infectious mechanisms. We attempt to delineate the features that will enable to tailor the correct diagnosis and following the effective therapy.

Clinical Onset and Multiple Sclerosis Relapse after SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been associated with several neurological disorders including headache, facial palsy, encephalitis, stroke, demyelinating disorders. The present report will discuss cases of multiple sclerosis (MS) onset and relapse both beginning early after SARS-CoV-2 infection. In both cases, magnetic resonance imaging (MRI) showed widespread bilateral subcortical and periventricular active lesions. Serum IgG against SARS-CoV-2 Spike antigens confirmed seroconversion with titers that are considered not definitely protective against possible reinfection. We hypothesize that SARS-CoV-2 infection, as previously reported for other viruses, could drive an active inflammatory response that can contribute either to the onset of MS or its relapse. The presented data further support the importance of vaccination in individuals with MS.

Human endogenous retrovirus and multiple sclerosis: A review and transcriptome findings

Multiple Sclerosis is an autoimmune disease with an unknown etiology. Both genetic and environmental factors are believed to trigger MS autoimmunity. Among the environmental factors, infectious agents have been extensively investigated, and the Human Endogenous Retroviruses (HERVs), especially HERV-W, are believed to be associated with MS pathogenesis. HERVs are derived from ancestral infections and comprise around 8% of the human genome. Although most HERVs are silenced, retroviral genes may be expressed with virion formation. There is extensive evidence of the relationship between HERV-W and MS, including higher levels of HERV-W expression in MS patients, HERV-W protein detection in MS plaques, and the HERV-W env protein inducing an inflammatory response in in vitro and in vivo models. Here we discuss possible links of HERVs and the pathogenesis of MS and present new data regarding the diversity of HERVs expression in samples derived from MS patients.

Trifluoperazine reduces cuprizone-induced demyelination via targeting Nrf2 and IKB in mice

Multiple sclerosis (MS) is one of the most common neurodegenerative diseases. In this disease, the immune system attacks oligodendrocyte cells and the myelin sheath of myelinated neurons in the central nervous system, causing their destruction. These conditions lead to impaired conduction of nerve impulses and are manifested by symptoms such as weakness, fatigue, visual and motor disorders. This study aimed to evaluate the ability of trifluoperazine (TF) to improve cuprizone-induced behavioral and histopathological changes in the prefrontal cortex of C57BL/6 male mice. Demyelination was induced by adding 0.2% cuprizone (CPZ) to the standard animal diet for 6 weeks. Three doses of TF (0.5, 1 and 2 mg/kg/day; i.p.) were given once daily for the last 2 weeks of treatment. Treatment with CPZ induced a weight loss during 6 weeks of treatment compared to the control group, which was reversed by the administration of TF. Behavioral tests (pole test and rotarod performance test) showed a decrease in motor coordination and balance in the group treated with CPZ (P < 0.01). Treatment with TF during the last two weeks was able to improve these motor deficiencies. Histopathological examination also evidenced an increase in demyelination in the CPZ group, which was improved by TF administration. In addition, CPZ intake significantly decreased the cerebral cortex levels of p-Nrf2 (P < 0.001) and increased the levels of p-IKB (P < 0.001) and, these changes were normalized in the TF groups. TF administration also reversed the increased levels of nitrite and the reduced activity of the antioxidant enzyme superoxide dismutase associated with CPZ exposure. TF can to reduce the harmful effects of CPZ by reducing the demyelination and modulating the Nrf2 and NF-kB signaling pathways.

An updated review of teriflunomide's use in multiple sclerosis

Teriflunomide, a once daily, oral disease-modifying therapy, has demonstrated consistent efficacy, safety and tolerability in patients with relapsing forms of multiple sclerosis (MS) and with a first clinical episode suggestive of MS treated up to 12 years. This review is an update to a previous version that examined data from the teriflunomide core clinical development program and extension studies. Data have since become available from active comparator trials with other disease-modifying therapies, treatment-related changes in brain volume (analyzed using structural image evaluation using normalization of atrophy) and real-world evidence including patient-reported outcomes. Initial data on the potential antiviral effects of teriflunomide in patients with MS, including case reports of patients infected with the 2019 novel coronavirus (SARS-CoV-2), are also presented.

RNA Sequencing of CD4+ T Cells in Relapsing-Remitting Multiple Sclerosis Patients at Relapse: Deciphering the Involvement of Novel genes and Pathways

CD4⁺ T cells are known as a noteworthy potential modulator of inflammation in multiple sclerosis (MS). In the current study, we investigated the transcriptome profile of CD4⁺ T cells in patients with relapsing-remitting MS (RRMS) at the relapse phase. We performed RNA sequencing of CD4⁺ T cells isolated from four relapsing-remitting MS (RRMS) patients at the relapse phase and four age- and sex-matched healthy controls. The edgeR statistical method was employed to determine differentially expressed genes (DEGs). Gene set enrichment analysis was subsequently performed. Applying a physical interaction network, genes with higher degrees were selected as hub genes. A total of 1278 and 1034 genes were defined at significantly higher or lower levels, respectively, in CD4⁺ T cells of RRMS patients at the relapse phase as compared with healthy controls. The top up- and downregulated genes were JAML and KDM3A. The detected DEGs were remarkable on chromosomes 1 and 2, respectively. The DEGs were mainly enriched in the pathways "regulation of transcription, DNA-templated," "regulation of B cell receptor signaling pathway," "protein phosphorylation," "epidermal growth factor receptor signaling pathway," and "positive regulation of neurogenesis." Moreover, 16 KEGG pathways mostly associated with the immune system and viral infections were enriched. In the constructed physical interaction networks, UBA52 and TP53 were shown to be the most highly ranked hub genes among upregulated and downregulated genes, respectively. By applying global transcriptome profiling of CD4⁺ T cells, we deciphered the involvement of several novel genes and pathways in MS pathogenesis. The present results must be confirmed by in vivo and in vitro studies.

Glial cell response to Epstein-Barr Virus infection: A plausible contribution to virus-associated inflammatory reactions in the brain

Epstein-Barr Virus (EBV) is clinically related to various neurological ailments. The manipulation of neural homeostasis through altered glial cells functions is enigmatic. We investigated EBV mediated nuances in glial cells through direct infection (group-1) or by supplementing them with EBV-infected lymphocytes (PBMCs) supernatant (group-3). Also, the cells were co-cultured with infected PBMCs (group-2). Upon confirmation of infection in U-87 MG through qRT-PCR, the gene expression of crucial molecules was analysed. We reported enhanced expression of IL6 in group-1 and 3 unlike group-2. PBMCs migrated and invaded the matrigel significantly when exposed to group-1 and 3 conditions. Thus, EBV may aid neuroinflammatory reactions through PBMCs infiltration. Also, the exposure of neurons to conditioned supernatant from group-2 caused reduced neuronal healing. Additionally, group-1 milieu contained chemical modulators that induced glial cells death and reduced NF-κB. Conclusively, the three modes of EBV infection can influence glial cells' functions to maneuver the microenvironment distinctly.

Herpesviruses and the hidden links to Multiple Sclerosis neuropathology

Herpesviruses like Epstein-Barr virus, human herpesvirus (HHV)-6, HHV-1, VZV, and human endogenous retroviruses, have an age-old clinical association with multiple sclerosis (MS). MS is an autoimmune disease of the nervous system wherein the myelin sheath deteriorates. The most popular mode of virus mediated immune system manipulation is molecular mimicry. Numerous herpesvirus antigens are similar to myelin proteins. Other mechanisms described here include the activity of cytokines and autoantibodies produced by the autoreactive T and B cells, respectively, viral déjà vu, epitope spreading, CD46 receptor engagement, impaired remyelination etc. Overall, this review addresses the host-parasite association of viruses with MS.

Recurrent Herpes Simplex Virus Type 1 (HSV-1) Infection Modulates Neuronal Aging Marks in In Vitro and In Vivo Models

Herpes simplex virus 1 (HSV-1) is a widespread neurotropic virus establishing a life-long latent infection in neurons with periodic reactivations. Recent studies linked HSV-1 to neurodegenerative processes related to age-related disorders such as Alzheimer's disease. Here, we explored whether recurrent HSV-1 infection might accelerate aging in neurons, focusing on peculiar marks of aged cells, such as the increase in histone H4 lysine (K) 16 acetylation (ac) (H4K16ac); the decrease of H3K56ac, and the modified expression of Sin3/HDAC1 and HIRA proteins. By exploiting both in vitro and in vivo models of recurrent HSV-1 infection, we found a significant increase in H4K16ac, Sin3, and HDAC1 levels, suggesting that the neuronal response to virus latency and reactivation includes the upregulation of these aging markers. On the contrary, we found a significant decrease in H3K56ac that was specifically linked to viral reactivation and apparently not related to aging-related markers. A complex modulation of HIRA expression and localization was found in the brain from HSV-1 infected mice suggesting a specific role of this protein in viral latency and reactivation. Overall, our results pointed out novel molecular mechanisms through which recurrent HSV-1 infection may affect neuronal aging, likely contributing to neurodegeneration.

Hospital-diagnosed infections before age 20 and risk of a subsequent multiple sclerosis diagnosis

The involvement of specific viral and bacterial infections as risk factors for multiple sclerosis has been studied extensively. However, whether this extends to infections in a broader sense is less clear and little is known about whether risk of a multiple sclerosis diagnosis is associated with other types and sites of infections, such as of the CNS. This study aims to assess if hospital-diagnosed infections by type and site before age 20 years are associated with risk of a subsequent multiple sclerosis diagnosis and whether this association is explained entirely by infectious mononucleosis, pneumonia, and CNS infections. Individuals born in Sweden between 1970-1994 were identified using the Swedish Total Population Register (n = 2,422,969). Multiple sclerosis diagnoses from age 20 years and hospital-diagnosed infections before age 20 years were identified using the Swedish National Patient Register. Risk of a multiple sclerosis diagnosis associated with various infections in adolescence (11-19 years) and earlier childhood (birth-10 years) was estimated using Cox regression, with adjustment for sex, parental socioeconomic position, and infection type. None of the infections by age 10 years were associated with risk of a multiple sclerosis diagnosis. Any infection in adolescence increased the risk of a multiple sclerosis diagnosis (hazard ratio 1.33, 95% confidence interval 1.21-1.46) and remained statistically significant after exclusion of infectious mononucleosis, pneumonia, and CNS infection (hazard ratio 1.17, 95% confidence interval 1.06-1.30). CNS infection in adolescence (excluding encephalomyelitis to avoid including acute disseminated encephalitis) increased the risk of a multiple sclerosis diagnosis (hazard ratio 1.85, 95% confidence interval 1.11-3.07). The increased risk of a multiple sclerosis diagnosis associated with viral infection in adolescence was largely explained by infectious mononucleosis. Bacterial infections in adolescence increased risk of a multiple sclerosis diagnosis, but the magnitude of risk reduced after excluding infectious mononucleosis, pneumonia and CNS infection (hazard ratio 1.31, 95% confidence interval 1.13-1.51). Respiratory infection in adolescence also increased risk of a multiple sclerosis diagnosis (hazard ratio 1.51, 95% confidence interval 1.30-1.75), but was not statistically significant after excluding infectious mononucleosis and pneumonia. These findings suggest that a variety of serious infections in adolescence, including novel evidence for CNS infections, are risk factors for a subsequent multiple sclerosis diagnosis, further demonstrating adolescence is a critical period of susceptibility to environmental exposures that raise the risk of a multiple sclerosis diagnosis. Importantly, this increased risk cannot be entirely explained by infectious mononucleosis, pneumonia, or CNS infections.

The Role of Natural Killer Cells in Autoimmune Diseases

Natural killer (NK) cells, the large granular lymphocytes differentiated from the common lymphoid progenitors, were discovered in early 1970’s. They are members of innate immunity and were initially defined by their strong cytotoxicity against virus-infected cells and by their important effector functions in anti-tumoral immune responses. Nowadays, NK cells are classified among the recently discovered innate lymphoid cell subsets and have capacity to influence both innate and adaptive immune responses. Therefore, they can be considered as innate immune cells that stands between the innate and adaptive arms of immunity. NK cells don’t express T or B cell receptors and are recognized by absence of CD3. There are two major subgroups of NK cells according to their differential expression of CD16 and CD56. While CD16⁺CD56^dim subset is best-known by their cytotoxic functions, CD16^-CD56^bright NK cell subset produces a bunch of cytokines comparable to CD4⁺ T helper cell subsets. Another subset of NK cells with production of interleukin (IL)-10 was named as NK regulatory cells, which has suppressive properties and could take part in immune-regulatory responses. Activation of NK cells is determined by a delicate balance of cell-surface receptors that have either activating or inhibitory properties. On the other hand, a variety of cytokines including IL-2, IL-12, IL-15, and IL-18 influence NK cell activity. NK-derived cytokines and their cytotoxic functions through induction of apoptosis take part in regulation of the immune responses and could contribute to the pathogenesis of many immune mediated diseases including ankylosing spondylitis, Behçet’s disease, multiple sclerosis, rheumatoid arthritis, psoriasis, systemic lupus erythematosus and type-1 diabetes. Dysregulation of NK cells in autoimmune disorders may occur through multiple mechanisms. Thanks to the rapid developments in biotechnology, progressive research in immunology enables better characterization of cells and their delicate roles in the complex network of immunity. As NK cells stand in between innate and adaptive arms of immunity and “bridge” them, their contribution in inflammation and immune regulation deserves intense investigations. Better understanding of NK-cell biology and their contribution in both exacerbation and regulation of inflammatory disorders is a requisite for possible utilization of these multi-faceted cells in novel therapeutic interventions.

Unbiased examination of genome-wide human endogenous retrovirus transcripts in MS brain lesions

BACKGROUND

Human endogenous retrovirus (HERV) expression in multiple sclerosis (MS) brain lesions may contribute to chronic inflammation, but expression of genome-wide HERVs in different MS lesions is unknown.

OBJECTIVE

We examined the HERV expression landscape in different MS lesions compared to control brains.

METHODS

Transcripts from 71 MS brain samples and 25 control WM were obtained by next-generation RNA sequencing and mapped against HERV transcripts across the human genome. Differential expression of mapped HERV-W and HERV-H reads between MS lesion types and controls was analysed.

RESULTS

Out of 6.38 billion high-quality paired end reads, 174 million reads (2.73%) mapped to HERV transcripts. There was no difference in HERVs expression level between MS and control brains, but HERV-W transcripts were significantly reduced in chronic active lesions. Of the four HERV-W transcripts exclusively present in MS, ERV3633503 located on chromosome 7q21.13 close to the MS genetic risk locus had the highest number of reads. In the HERV-H family, 75% of transcripts located to nearby 7q21-22 were overrepresented in MS, and ERV3643914 was expressed more than 16 times in MS compared to control brains.

CONCLUSION

Novel HERV-W and HERV-H transcripts located at chromosome 7 regions were uniquely expressed in MS lesions, indicating their potential role in brain lesion evolution.

Viral infections and their relationship to neurological disorders

The chronic dysfunction of neuronal cells, both central and peripheral, a characteristic of neurological disorders, may be caused by irreversible damage and cell death. In 2016, more than 276 million cases of neurological disorders were reported worldwide. Moreover, neurological disorders are the second leading cause of death. Generally, the etiology of neurological diseases is not fully understood. Recent studies have related the onset of neurological disorders to viral infections, which may cause neurological symptoms or lead to immune responses that trigger these pathological signs. Currently, this relationship is mostly based on epidemiological data on infections and seroprevalence of patients who present with neurological disorders. The number of studies aiming to elucidate the mechanism of action by which viral infections may directly or indirectly contribute to the development of neurological disorders has been increasing over the years but these studies are still scarce. Comprehending the pathogenesis of these diseases and exploring novel theories may favor the development of new strategies for diagnosis and therapy in the future. Therefore, the objective of the present study was to review the main pieces of evidence for the relationship between viral infection and neurological disorders such as Alzheimer's disease, Parkinson's disease, Guillain-Barré syndrome, multiple sclerosis, and epilepsy. Viruses belonging to the families Herpesviridae, Orthomyxoviridae, Flaviviridae, and Retroviridae have been reported to be involved in one or more of these conditions. Also, neurological symptoms and the future impact of infection with SARS-CoV-2, a member of the family Coronaviridae that is responsible for the COVID-19 pandemic that started in late 2019, are reported and discussed.

Epstein-Barr Virus and Multiple Sclerosis

Multiple sclerosis (MS) is a neurologic disease affecting myelinated nerves in the central nervous system (CNS). The disease often debuts as a clinically isolated syndrome, e.g., optic neuritis (ON), which later develops into relapsing-remitting (RR) MS, with temporal attacks or primary progressive (PP) MS. Characteristic features of MS are inflammatory foci in the CNS and intrathecal synthesis of immunoglobulins (Igs), measured as an IgG index, oligoclonal bands (OCBs), or specific antibody indexes. Major predisposing factors for MS are certain tissue types (e.g., HLA DRB1*15:01), vitamin D deficiency, smoking, obesity, and infection with Epstein-Barr virus (EBV). Many of the clinical signs of MS described above can be explained by chronic/recurrent EBV infection and current models of EBV involvement suggest that RRMS may be caused by repeated entry of EBV-transformed B cells to the CNS in connection with attacks, while PPMS may be caused by more chronic activity of EBV-transformed B cells in the CNS. In line with the model of EBV's role in MS, new treatments based on monoclonal antibodies (MAbs) targeting B cells have shown good efficacy in clinical trials both for RRMS and PPMS, while MAbs inhibiting B cell mobilization and entry to the CNS have shown efficacy in RRMS. Thus, these agents, which are now first line therapy in many patients, may be hypothesized to function by counteracting a chronic EBV infection.

Computational modeling of the immune response in multiple sclerosis using epimod framework

BACKGROUND

Multiple Sclerosis (MS) represents nowadays in Europe the leading cause of non-traumatic disabilities in young adults, with more than 700,000 EU cases. Although huge strides have been made over the years, MS etiology remains partially unknown. Furthermore, the presence of various endogenous and exogenous factors can greatly influence the immune response of different individuals, making it difficult to study and understand the disease. This becomes more evident in a personalized-fashion when medical doctors have to choose the best therapy for patient well-being. In this optics, the use of stochastic models, capable of taking into consideration all the fluctuations due to unknown factors and individual variability, is highly advisable.

RESULTS

We propose a new model to study the immune response in relapsing remitting MS (RRMS), the most common form of MS that is characterized by alternate episodes of symptom exacerbation (relapses) with periods of disease stability (remission). In this new model, both the peripheral lymph node/blood vessel and the central nervous system are explicitly represented. The model was created and analysed using Epimod, our recently developed general framework for modeling complex biological systems. Then the effectiveness of our model was shown by modeling the complex immunological mechanisms characterizing RRMS during its course and under the DAC administration.

CONCLUSIONS

Simulation results have proven the ability of the model to reproduce in silico the immune T cell balance characterizing RRMS course and the DAC effects. Furthermore, they confirmed the importance of a timely intervention on the disease course.

The Role of Extracellular Vesicles in Demyelination of the Central Nervous System

It is being increasingly demonstrated that extracellular vesicles (EVs) are deeply involved in the physiology of the central nervous system (CNS). Processes such as synaptic activity, neuron-glia communication, myelination and immune response are modulated by EVs. Likewise, these vesicles may participate in many pathological processes, both as triggers of disease or, on the contrary, as mechanisms of repair. EVs play relevant roles in neurodegenerative disorders such as Alzheimer’s or Parkinson’s diseases, in viral infections of the CNS and in demyelinating pathologies such as multiple sclerosis (MS). This review describes the involvement of these membrane vesicles in major demyelinating diseases, including MS, neuromyelitis optica, progressive multifocal leukoencephalopathy and demyelination associated to herpesviruses.

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.

B Cells in Multiple Sclerosis and Virus-Induced Neuroinflammation

Neuroinflammation can be defined as an inflammatory response within the central nervous system (CNS) mediated by a complex crosstalk between CNS-resident and infiltrating immune cells from the periphery. Triggers for neuroinflammation not only include pathogens, trauma and toxic metabolites, but also autoimmune diseases such as neuromyelitis optica spectrum disorders and multiple sclerosis (MS) where the inflammatory response is recognized as a disease-escalating factor. B cells are not considered as the first responders of neuroinflammation, yet they have recently gained focus as a key component involved in the disease pathogenesis of several neuroinflammatory disorders like MS. Traditionally, the prime focus of the role of B cells in any disease, including neuroinflammatory diseases, was their ability to produce antibodies. While that may indeed be an important contribution of B cells in mediating disease pathogenesis, several lines of recent evidence indicate that B cells are multifunctional players during an inflammatory response, including their ability to present antigens and produce an array of cytokines. Moreover, interaction between B cells and other cellular components of the immune system or nervous system can either promote or dampen neuroinflammation depending on the disease. Given that the interest in B cells in neuroinflammation is relatively new, the precise roles that they play in the pathophysiology and progression of different neuroinflammatory disorders have not yet been well-elucidated. Furthermore, the possibility that they might change their function during the course of neuroinflammation adds another level of complexity and the puzzle remains incomplete. Indeed, advancing our knowledge on the role of B cells in neuroinflammation would also allow us to tackle these disorders better. Here, we review the available literature to explore the relationship between autoimmune and infectious neuroinflammation with a focus on the involvement of B cells in MS and viral infections of the CNS.

Advances in Multiple Sclerosis Research-Series I

Designing immunotherapeutics, drugs, and anti-inflammatory reagents has been at the forefront of autoimmune research, in particular, multiple sclerosis, for over 20 years. Delivery methods that are used to modulate effective and long-lasting immune responses have been the major focus. This Special Issue, “Advances in Multiple Sclerosis Research—Series I”, focused on delivery methods used for immunotherapeutic approaches, drug design, anti-inflammatories, identification of markers, methods for detection and monitoring MS and treatment modalities. The issue gained much attention with 20 publications, and, as a result, we launched Series II with the deadline for submission being 30 April 2021.

Search for viral agents in cerebrospinal fluid in patients with multiple sclerosis using real-time PCR and metagenomics

Multiple sclerosis (MS) is a chronic, immune-mediated demyelinating disease of the central nervous system of unclear etiology, but there is some evidence that viral infections could be responsible for triggering autoimmune mechanisms against myelin. We searched for viral RNA and DNA in cerebrospinal fluid (CSF) of 34 MS patients and 13 controls using RT-PCR/PCR against common neurotropic viruses. In addition, shotgun DNA- and RNA-based metagenomics were done in 13 MS patients and 4 controls. Specific quantitative real-time RT-PCR/PCR testing revealed the presence of viral nucleic acid in seven (20.59%) MS patients and in one (7.69%) control patient. In MS patients the most frequently detected was human herpesvirus type 6 (HHV-6; 3 cases; 8.82%); followed by Epstein-Barr virus (EBV; 2 cases; 5.88%), varicella zoster virus (VZV; 1 case; 2.94%) and Enterovirus (EV; 1 case; 2.94%). The single identified virus among controls was EBV (7.69%). DNA and RNA metagenomic assays did not identify any known eukaryotic viruses even though three of the analyzed samples were low-level positive by specific quantitative real-time PCR. In conclusion, we detected the presence of Herpesviridae and occasionally Enteroviridae in CSF from patients with MS but their prevalence was not significantly higher than among controls. Metagenomic analysis seems to be less sensitive than real-time RT-PCR/PCR and it did not detect any potential viral pathogens.

Molecular Detection of Epstein-Barr Virus, Human Herpes Virus 6, Cytomegalovirus, and Hepatitis B Virus in Patients with Multiple Sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic disease with significant morbidity. A wide spectrum of risk factors has been suggested that triggers the development of MS. Among them, several viral infections have been implicated to play a role in MS pathogenesis.

We aimed to evaluate the relationship between viral diseases, including Epstein–Barr virus (EBV), human herpes virus 6 (HHV-6), cytomegalovirus (CMV), and hepatitis B virus (HBV) and MS in the present case-control study.

METHODS

About 100 patients with confirmed MS and age- and sex-matched individuals were selected as case and control groups, respectively. The patients were randomly selected from individuals diagnosed by neurologists based on the clinical signs and symptoms and imaging procedures.

RESULTS

More than 100 patients with MS and patients who were referred for other causes were analyzed for the presence of DNA of EBV, HHV6, CMV, and HBV separately. 9.37% of the control group had a positive test for the DNA of EBV in a real-time polymerase chain reaction (PCR), while the frequency of positive test result was zero in the case group (p = 0.0012). HBV DNA was not detected in both the case and control groups. The prevalence of CMV was 0.88 and zero in the control and case groups, respectively (p = 0.3410). For HHV6, 9.73 % of the control group had a positive result, while this test was positive in 5.88% of the patients with MS (p = 0.2959).

CONCLUSION

We detected a significantly higher number of individuals with DNA of EBV in their blood among the control group compared with the case group. In conclusion, the results suggest a surprisingly adverse association between MS and EBV, and no association was found between the presence of DNA of HBV, CMV, and HHV6 and MS.

The expression profile of virus-recognizing toll-like receptors in natural killer cells of Cypriot multiple sclerosis patients

Objective

The exact aetiology of multiple sclerosis (MS) remains elusive, although several environmental and genetic risk factors have been implicated to varying degrees. Among the environmental risk factors, viral infections have been suggested as strong candidates contributing to MS pathology/progression. Viral recognition and control are largely tasked to the NK cells via TLR recognition and various cytotoxic and immunoregulatory functions. Additionally, the complex roles of different TLRs in MS pathology are highlighted in multiple, often contradictory, studies. The present work aims to analyse the TLR expression profile of NK cells isolated from MS patients. Highly purified CD56⁺CD3⁻ NK cells isolated from peripheral blood of MS patients (n = 19) and healthy controls (n = 20) were analysed via flow cytometry for their expression of viral antigen-recognizing TLRs (TLR2, TLR3, TLR7, and TLR9).

Results

No difference was noted in TLR expression between MS patients and healthy controls. These results aim to supplement previous findings which study expressional or functional differences in TLRs present in various subsets of the immune system in MS, thus aiding in a better understanding of MS as a complex multifaceted disease.

The Role of Herpes Simplex Virus Type 1 Infection in Demyelination of the Central Nervous System

Herpes simplex type 1 (HSV-1) is a neurotropic virus that infects the peripheral and central nervous systems. After primary infection in epithelial cells, HSV-1 spreads retrogradely to the peripheral nervous system (PNS), where it establishes a latent infection in the trigeminal ganglia (TG). The virus can reactivate from the latent state, traveling anterogradely along the axon and replicating in the local surrounding tissue. Occasionally, HSV-1 may spread trans-synaptically from the TG to the brainstem, from where it may disseminate to higher areas of the central nervous system (CNS). It is not completely understood how HSV-1 reaches the CNS, although the most accepted idea is retrograde transport through the trigeminal or olfactory tracts. Once in the CNS, HSV-1 may induce demyelination, either as a direct trigger or as a risk factor, modulating processes such as remyelination, regulation of endogenous retroviruses, or molecular mimicry. In this review, we describe the current knowledge about the involvement of HSV-1 in demyelination, describing the pathways used by this herpesvirus to spread throughout the CNS and discussing the data that suggest its implication in demyelinating processes.

IFN-γ and TNF-α Gene Polymorphisms in Multiple Sclerosis Patients in Northwest Iran

BACKGROUND

Cytokines are polypeptides that play critical roles in immune responses. Gene polymorphisms occurring in the inflammatory cytokines are taking a role in autoimmune diseases, including multiple sclerosis (MS), which may induce inappropriate immune responses.

OBJECTIVE

The aim of this study was to investigate the allelic and genotypic frequencies of interferon gamma gene (IFN-γ) at +874A/T locus and tumor necrosis factor (TNF-α) at+308A/G locus in MS patients of Azeri population.

METHODS

At first, a questionnaire was prepared for each of 240 healthy, non-relative, and 152 Azeri MS patients before obtaining the blood sample from all subjects. After DNA extraction, the frequency of alleles and genotypes of the IFN-γ and TNF-α genes at +874A/T and -308G/A loci, respectively, were determined by allele-specific PCR method. Finally, the frequencies were compared between control and MS patients by chi-square test (x²-test) and p<0.05 was considered significant.

RESULTS

In the IFN-γ +874A/T gene single nucleotide polymorphism (SNP), the most allelic and genotypic frequencies in MS patients were the A allele, 55.26% (p=0.04) and the AT genotype, 52.63% (p=0.048). In healthy individuals, it was 65.42% for the A allele and 45.42% for the AA genotype. For the TNF-α 308 G/A SNP, the highest allelic and genotypic frequencies in MS patients were the G allele with 55.92% (p<0.001) and AG genotype with 61.84%, and in healthy subjects, the allelic and genotypic frequencies were 84.2% and 70.8% for the G allele and GG genotype, respectively.

CONCLUSION

Head trauma, the infection with the herpes virus and Mycoplasma pneumonia, frequent colds and high consumption of canned foods provide grounds for MS. The T allele in the IFN-γ gene (+874) and the genotypes of AA and AG at the TNF-α gene (-308) at the position-308 were considered as potential risk factors for MS. Therefore, the polymorphisms in cytokine genes and following changes in their expression levels can be effective in susceptibility to MS.

Alcohol and multiple sclerosis: an immune system-based review

Multiple sclerosis is a chronic inflammatory disease of the central nervous system (CNS). Although the exact etiology of multiple sclerosis is unknown, researchers suggest that genetic, environmental, and microbial factors play a central role in causing multiple sclerosis. Pathology of multiple sclerosis is based on inflammation as T cells enter the brain via disruptions in the blood-brain barrier, recognizing myelin as foreign antigen; and as a result, the T cells attack myelin and start the inflammatory processes, enhancing inflammatory cytokines and antibodies. Since previous studies show ethanol can suppress the immune system such as innate, humoral, and cellular immunity and increases the production of anti-inflammatory cytokines, we hypothesized maybe ethanol also have ameliorating effects on multiple sclerosis symptoms. Although alcohol induces apoptosis in oligodendrocytes and neurons, causing demyelination and affects CNS directly, in this study we will investigate ethanol's effects on some aspects of the immune system in multiple sclerosis.