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Multiple sclerosis (MS) is an inflammatory neurological disease of the central nervous system with a subclinical phase preceding frank neuroinflammation. CD8 + T cells are abundant within MS lesions, but their potential role in disease pathology remains unclear. Using high-throughput single-cell RNA sequencing and single-cell T cell receptor analysis, we compared CD8 + T cell clones from the blood and cerebrospinal fluid (CSF) of monozygotic twin pairs in which the cotwin had either no or subclinical neuroinflammation (SCNI). We identified peripheral MS-associated immunological and metabolic alterations indicative of an enhanced migratory, proinflammatory, and activated CD8 + T cell phenotype, which was also evident in cotwins with SCNI and in an independent validation cohort of people with MS. Together, our in-depth single-cell analysis indicates a disease-driving proinflammatory role of infiltrating CD8 + T cells and identifies potential immunological and metabolic therapeutic targets in both prodromal and definitive stages of the disease.

Epstein-Barr virus (EBV) infection precedes multiple sclerosis (MS) pathology and cross-reactive antibodies might link EBV infection to CNS autoimmunity. As an altered anti-EBV T cell reaction was suggested in MS, we queried peripheral blood T cell receptor β chain (TCRβ) repertoires of 1,395 MS patients, 887 controls, and 35 monozygotic, MS-discordant twin pairs for multimer-confirmed, viral antigen-specific TCRβ sequences. We detected more MHC-I-restricted EBV-specific TCRβ sequences in MS patients. Differences in genetics or upbringing could be excluded by validation in monozygotic twin pairs discordant for MS. Anti-VLA-4 treatment amplified this observation, while interferon β- or anti-CD20 treatment did not modulate EBV-specific T cell occurrence. In healthy individuals, EBV-specific CD8+ T cells were of an effector-memory phenotype in peripheral blood and cerebrospinal fluid. In MS patients, cerebrospinal fluid also contained EBV-specific central-memory CD8+ T cells, suggesting recent priming. Therefore, MS is not only preceded by EBV infection, but also associated with broader EBV-specific TCR repertoires, consistent with an ongoing anti-EBV immune reaction in MS., (© 2022 Schneider-Hohendorf et al.)

During the past decade, research has revealed that the vast community of micro-organisms that inhabit the gut - known as the gut microbiota - is intricately linked to human health and disease, partly as a result of its influence on systemic immune responses. Accumulating evidence demonstrates that these effects on immune function are important in neuroinflammatory diseases, such as multiple sclerosis (MS), and that modulation of the microbiome could be therapeutically beneficial in these conditions. In this Review, we examine the influence that the gut microbiota have on immune function via modulation of serotonin production in the gut and through complex interactions with components of the immune system, such as T cells and B cells. We then present evidence from studies in mice and humans that these effects of the gut microbiota on the immune system are important in the development and course of MS. We also consider how strategies for manipulating the composition of the gut microbiota could be used to influence disease-related immune dysfunction and form the basis of a new class of therapeutics. The strategies discussed include the use of probiotics, supplementation with bacterial metabolites, transplantation of faecal matter or defined microbial communities, and dietary intervention. Carefully designed studies with large human cohorts will be required to gain a full understanding of the microbiome changes involved in MS and to develop therapeutic strategies that target these changes., (© 2022. Springer Nature Limited.)

Progressive multiple sclerosis (PMS) is clinically distinct from relapsing-remitting MS (RRMS). In PMS, clinical disability progression occurs independently of relapse activity. Furthermore, there is increasing evidence that the pathological mechanisms of PMS and RRMS are different. Current therapeutic options for the treatment of PMS remain inadequate, although ocrelizumab, a B-cell-depleting antibody, is now available as the first approved therapeutic option for primary progressive MS. Recent advances in understanding the pathophysiology of PMS provide hope for new innovative therapeutic options: these include antibody therapies with anti-inflammatory, neuroprotective, and/or remyelination-fostering effects. In this review, we summarize the relevant trial data relating to antibody therapy and consider future antibody options for treating PMS., (© 2022. The Author(s).)

Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system underpinned by partially understood genetic risk factors and environmental triggers and their undefined interactions 1,2 . Here we investigated the peripheral immune signatures of 61 monozygotic twin pairs discordant for MS to dissect the influence of genetic predisposition and environmental factors. Using complementary multimodal high-throughput and high-dimensional single-cell technologies in conjunction with data-driven computational tools, we identified an inflammatory shift in a monocyte cluster of twins with MS, coupled with the emergence of a population of IL-2 hyper-responsive transitional naive helper T cells as MS-related immune alterations. By integrating data on the immune profiles of healthy monozygotic and dizygotic twin pairs, we estimated the variance in CD25 expression by helper T cells displaying a naive phenotype to be largely driven by genetic and shared early environmental influences. Nonetheless, the expanding helper T cells of twins with MS, which were also elevated in non-twin patients with MS, emerged independent of the individual genetic makeup. These cells expressed central nervous system-homing receptors, exhibited a dysregulated CD25-IL-2 axis, and their proliferative capacity positively correlated with MS severity. Together, our matched-pair analysis of the extended twin approach allowed us to discern genetically and environmentally determined features of an MS-associated immune signature., (© 2022. The Author(s).)

Background: Progressive forms of multiple sclerosis (MS) affect more than 1 million individuals globally. Recent approvals of ocrelizumab for primary progressive MS and siponimod for active secondary progressive MS have opened the therapeutic door, though results from early trials of neuroprotective agents have been mixed. The recent introduction of the term 'active' secondary progressive MS into the therapeutic lexicon has introduced potential confusion to disease description and thereby clinical management., Objective: This paper reviews recent progress, highlights continued knowledge and proposes, on behalf of the International Progressive MS Alliance, a global research strategy for progressive MS., Methods: Literature searches of PubMed between 2015 and May, 2021 were conducted using the search terms "progressive multiple sclerosis", "primary progressive multiple sclerosis", "secondary progressive MS". Proposed strategies were developed through a series of in-person and virtual meetings of the International Progressive MS Alliance Scientific Steering Committee., Results: Sustaining and accelerating progress will require greater understanding of underlying mechanisms, identification of potential therapeutic targets, biomarker discovery and validation, and conduct of clinical trials with improved trial design. Encouraging developments in symptomatic and rehabilitative interventions are starting to address ongoing challenges experienced by people with progressive MS., Conclusion: We need to manage these challenges and realise the opportunities in the context of a global research strategy, which will improve quality of life for people with progressive MS.

Competing Interests: RH declares no competing interests.

Multiple sclerosis (MS) disease risk is associated with reduced sun-exposure. This study assessed the relationship between measures of sun exposure (vitamin D [vitD], latitude) and MS severity in the setting of two multicenter cohort studies ( n NationMS = 946, n BIONAT = 990). Additionally, effect-modification by medication and photosensitivity-associated MC1R variants was assessed. High serum vitD was associated with a reduced MS severity score (MSSS), reduced risk for relapses, and lower disability accumulation over time. Low latitude was associated with higher vitD, lower MSSS, fewer gadolinium-enhancing lesions, and lower disability accumulation. The association of latitude with disability was lacking in IFN-β-treated patients. In carriers of MC1R :rs1805008(T), who reported increased sensitivity toward sunlight, lower latitude was associated with higher MRI activity, whereas for noncarriers there was less MRI activity at lower latitudes. In a further exploratory approach, the effect of ultraviolet (UV)-phototherapy on the transcriptome of immune cells of MS patients was assessed using samples from an earlier study. Phototherapy induced a vitD and type I IFN signature that was most apparent in monocytes but that could also be detected in B and T cells. In summary, our study suggests beneficial effects of sun exposure on established MS, as demonstrated by a correlative network between the three factors: Latitude, vitD, and disease severity. However, sun exposure might be detrimental for photosensitive patients. Furthermore, a direct induction of type I IFNs through sun exposure could be another mechanism of UV-mediated immune-modulation in MS., Competing Interests: Competing interest statement: H.W. received honoraria and consultation fees from Bayer Healthcare, Biogen, Fresenius Medical Care, GlaxoSmithKline, GW Pharmaceuticals, Merck Serono, Novartis, Sanofi Genzyme, and Teva Pharma. K.L. is coinventor on patent no. US 2016/0158322 A1 entitled “NDP-MSH for treatment of inflammatory and/or neurodegenerative disorders of the CNS.” A.S. received speaker honoraria and/or travel compensation for activities with Almirall Hermal GmbH, Biogen, Merck, Novartis, Roche and Sanofi Genzyme, none related to this work. R.G. serves on scientific advisory boards for Teva Pharmaceutical Industries Ltd. (Teva), Biogen Idec, Bayer Schering Pharma, and Novartis; has received speaker honoraria from Biogen Idec, Teva, Bayer Schering Pharma, and Novartis; serves as editor for Therapeutic Advances in Neurological Diseases, and is on the editorial boards of Experimental Neurology and the Journal of Neuroimmunology; and receives research support from Teva, Biogen Idec, Bayer Schering Pharma, Genzyme, Merck Serono, and Novartis, none related to this work. L.K. receives honoraria for lecturing and travel expenses for attending meetings from Biogen, Merck, Sanofi Genzyme, Novartis and Roche; her research is funded by the German Ministry for Education and Research (BMBF), Deutsche Forschungsgemeinschaft (DFG), Interdisciplinary Center for Clinical Studies (IZKF) Muenster, Biogen, Merck, and Novartis. M.A.F. received honoraria for consultation and travel expenses from Biogen, Merck KGaA, Novartis, and Roche; his research is funded by the BMBF, DFG, Landesforschungsförderung Hamburg, Gemeinnützige Hertie-Stiftung, and Else Kröner-Fresenius-Stiftung. S.G.M. receives honoraria for lecturing, and travel expenses for attending meetings from Almirall, Amicus Therapeutics Germany, Bayer Health Care, Biogen, Celgene, Diamed, Genzyme, MedDay Pharmaceuticals, Merck Serono, Novartis, Novo Nordisk, ONO Pharma, Roche, Sanofi-Aventis, Chugai Pharma, QuintilesIMS, and Teva; his research is funded by the BMBF, DFG, Else Kröner Fresenius Foundation, German Academic Exchange Service, Hertie Foundation, IZKF Muenster, German Foundation Neurology and Almirall, Amicus Therapeutics Germany, Biogen, Diamed, Fresenius Medical Care, Genzyme, Merck Serono, Novartis, ONO Pharma, Roche, and Teva. R.H. has received grant support from Biogen, Genzyme-Sanofi, Merck Serono, Novartis, Teva, and personal fees from Actelion, Biogen, Genzyme-Sanofi, Medday, Merck Serono, Novartis, Roche, and Teva. T.K. has received travel expenses and personal compensation from Bayer Healthcare, Teva Pharma, Merck, Novartis Pharma, Sanofi-Aventis/Genzyme, Roche, and Biogen, as well as grant support from Bayer Schering AG, Novartis, and Chugai Pharma. U.Z. has received grants from DFG, BMBF, the European Research Council, Bristol Myers Squibb, Janssen Pharmaceuticals NV, Servier, and Biogen Idec, and personal consultation fees from Pfizer GmbH, Bayer Vital GmbH, and CorTec GmbH. F.Z. received funds for scientific consultation or research by DFG, BMBF, the Pharmaceutical Management Science Association, Novartis, Octapharma, Merck Serono, ONO Pharma, Biogen, Genzyme, Celgene, Roche, Sanofi Aventis. A.S.-M. received travel expenses and research support from Novartis. C.C.G. received speaker honoraria and travel expenses for attending meetings from Biogen, Euroimmun, Genzyme, MyLan, Novartis Pharma GmbH, and Bayer Health Care, none related to this study; her work is funded by Biogen, Novartis, the BMBF (01Gl1603A), the DFG (GR3946/3-1, SFB Transregio 128 A09), the European Union (Horizon2020, ReSToRE), the IZKF, and the Innovative Medizinische Forschung. D.B. receives lectures, congress invitation, board participation with Bayer, Biogen, Medday, Merck, Novartis, Roche, Sanofi Genzyme, and Teva. B.T. received personal speaker honoraria and consultancy fees as a speaker and advisor from Alexion, Bayer Healthcare, Biogen, CSL Behring, GILEAD, GRIFOLS, Merck Serono, Novartis, Octapharma, Roche, Sanofi Genzyme, Teva, and UCB Pharma; his university received unrestricted research grants from Biogen-Idec, Novartis, Teva, Bayer Healthcare, CSL-Behring, GRIFOLS, Octapharma, Sanofi Genzyme, and UCB Pharma. F.T.B. has received, through his institution, grant support and/or travel reimbursement to attend scientific meetings from Actelion, Bayer, Biogen, Merck, Novartis, Sanofi Genzyme, and Teva; he has received personal honoraria for speaking or advisory board activities from Actelion, Bayer, Biogen, Merck, Novartis, Roche, and Sanofi Genzyme; his research is funded, in part, by the DFG and the BMBF. C.W. has received institutional support from Novartis, Sanofi Genzyme, Biogen, and Roche. H.-P.H. has received fees for consulting, speaking, and serving on steering committees from Bayer Healthcare, Biogen, GeNeuro, MedImmune, Merck, Novartis, Opexa, Receptos Celgene, Roche, Sanofi Genzyme, CSL Behring, Octapharma, and Teva, with approval by the Rector of Heinrich-Heine University. H.T. received speaker honoraria from Bayer, Biogen, Fresenius, Genzyme, Merck, Novartis, Roche, Siemens, and Teva; he serves as section editor for the Journal of Neurology, Psychiatry, and Brain Research; H.T. and his institution receives research support from the BMBF, DMSG, Fresenius, Genzyme, Merck, and Novartis, none related to this work. A.B. has received personal compensation from Merck, Biogen, Bayer Vital, Novartis, Teva, Roche, Celgene, Alexion, and Sanofi Genzyme, and grants for congress trips and participation from Biogen, Teva, Novartis, Sanofi Genzyme, Celgene, and Merck, none related to this work. C.L. received an endowed professorship supported by the Novartis foundation, has received consulting and speaker’s honoraria from Biogen-Idec, Bayer Schering, Novartis, Sanofi Genzyme, and Teva; and has received research scientific grant support from Merck-Serono and Novartis. B.W. received research grants and/or honoria from Merck Serono, Biogen, Teva, Novartis, Sanofi Genzyme, Bayer Healthcare, Roche, and research grants from the Dietmar Hopp Foundation, the Klaus Tschira Foundation, the BMBF, and the DFG. U.K.Z. received honoraria for lecturing and/or travel expenses for attending meetings from Almirall, Alexion, Bayer, Biogen, Celgene, Merck Serono, Novartis, Octapharma, Roche, Sanofi Genzyme, and Teva, as well as grant support from the BMBF and European Union, none related to this study; his research is funded by the BMBF, German Ministry of Economy, DFG, and European Union. S.B. has received honoria and compensation for travel from Biogen Idec, Merck Serono, Novartis, Sanofi Genzyme, and Roche. M.S. has received honoraria for scientific lectures or consultancy from Alexion, Bayer Healthcare, Biogen, CSL Behring, Grifols, MedDay, Merck-Serono, Novartis, Roche, Sanofi Genzyme, Takeda, and Teva; his institution received research support from Biogen, Sanofi-Genzyme, and Merck-Serono. R.A.L. received personal compensation from Celgene, Bayer Healthcare, Teva Pharma, Merck, Novartis Pharma, Sanofi-Aventis/Genzyme, Roche, and Biogen, as well as grant support from Novartis and Merck. F.W. served on the scientific advisory board of Genzyme, Merck Serono, and Novartis; he has received travel funding and/or speaker honoraria from Bayer, Biogen, Teva, Merck Serono, Novartis, and Pfizer; he is employed by Sana and received research support from the BMBF, Merck Serono, and Novartis. F.P. reported other support from Bayer, Novartis, Biogen-Idec, Teva, Sanofi-Aventis/Genzyme, Merck Serono, Alexion, Chugai, MedImmune, Roche, and Shire outside the submitted work; he has a post as academic editor for PLoS One and is associate editor for Neurology: Neuroimmunology & Neuroinflammation; he has scientific advisory board membership for Novartis and consulting fees from Sanofi Genzyme, Biogen-Idec, MedImmune, Shire, and Alexion; and research support from Bayer, Novartis, Biogen Idec, Teva, Sanofi-Aventis/Genzyme, Alexion, Merck Serono, the German Research Council, Werth Stiftung, German Ministry of Education and Research, Arthur Arnstein Stiftung Berlin, EU FP7 Framework Program, Arthur Arnstein Foundation Berlin, Guthy Jackson Charitable Foundation, and National Multiple Sclerosis of the United States. B.H. has served on scientific advisory boards for Novartis; he has served as data monitoring and safety committee member for AllergyCare and TG therapeutics; he or his institution have received speaker honoraria from Desitin; he holds part of two patents, one for the detection of antibodies against KIR4.1 in a subpopulation of MS patients and one for genetic determinants of neutralizing antibodies to interferon. All conflicts are not relevant to the topic of the study. F.L. has served on the advisory board of Roche and received travel funding from Teva. M.M. received research support from Merck Serono and Novartis as well as travel expenses for attending meetings from Merck Serono. K.L.-H. has received research support (to Technische Universität München) from Novartis, honoraria from Novartis and F. Hoffmann-La Roche, and compensation for travel expenses from Merck Serono., (Copyright © 2021 the Author(s). Published by PNAS.)

The success of clinical trials of selective B-cell depletion in patients with relapsing multiple sclerosis (MS) and primary progressive MS has led to a conceptual shift in the understanding of MS pathogenesis, away from the classical model in which T cells were the sole central actors and toward a more complex paradigm with B cells having an essential role in both the inflammatory and neurodegenerative components of the disease process. The role of B cells in MS was selected as the topic of the 27th Annual Meeting of the European Charcot Foundation. Results of the meeting are presented in this concise review, which recaps current concepts underlying the biology and therapeutic rationale behind B-cell-directed therapeutics in MS, and proposes strategies to optimize the use of existing anti-B-cell treatments and provide future directions for research in this area. ANN NEUROL 2021;89:13-23., (© 2020 American Neurological Association.)

Multiple genetic and non-heritable factors have been linked to the risk of multiple sclerosis (MS). These factors seem to contribute to disease pathogenesis before the onset of clinical symptoms, as suggested by incidental MRI evidence of subclinical MS neuropathology in individuals without clinical symptoms. Individuals with high familial risk for MS, such as first-degree relatives of patients with MS, can be studied by MRI to characterize the neuropathology during a subclinical period of MS. 16 studies published in English, which performed brain MRI on healthy individuals with high familial risk of MS were included in this scoping review. Studies suggest either no conclusive (5), or inconclusive yet considerable (4), or conclusive evidence (7) for the incidence of subclinical neuropathology, including focal and diffuse tissue damage. Across all studies, white matter lesions fulfilling MS criteria were observed in 86 of 613 individuals (14%). Future research is needed to evaluate the longitudinal dynamics and clinical relevance of preclinical imaging abnormalities in MS., (Copyright © 2021. Published by Elsevier Inc.)

Blood biomarkers of multiple sclerosis (MS) can provide a better understanding of pathophysiology and enable disease monitoring. Here, we performed quantitative shotgun lipidomics on the plasma of a unique cohort of 73 monozygotic twins discordant for MS. We analyzed 243 lipid species, evaluated lipid features such as fatty acyl chain length and number of acyl chain double bonds, and detected phospholipids that were significantly altered in the plasma of co-twins with MS compared to their non-affected siblings. Strikingly, changes were most prominent in ether phosphatidylethanolamines and ether phosphatidylcholines, suggesting a role for altered lipid signaling in the disease., (© 2020 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Autoimmune disorders of the central nervous system (CNS) comprise a broad spectrum of clinical entities. The stratification of patients based on the recognized autoantigen is of great importance for therapy optimization and for concepts of pathogenicity, but for most of these patients, the actual target of their autoimmune response is unknown. Here we investigated oligodendrocyte myelin glycoprotein (OMGP) as autoimmune target, because OMGP is expressed specifically in the CNS and there on oligodendrocytes and neurons. Using a stringent cell-based assay, we detected autoantibodies to OMGP in serum of 8/352 patients with multiple sclerosis, 1/28 children with acute disseminated encephalomyelitis and unexpectedly, also in one patient with psychosis, but in none of 114 healthy controls. Since OMGP is GPI-anchored, we validated its recognition also in GPI-anchored form. The autoantibodies to OMGP were largely IgG1 with a contribution of IgG4, indicating cognate T cell help. We found high levels of soluble OMGP in human spinal fluid, presumably due to shedding of the GPI-linked OMGP. Analyzing the pathogenic relevance of autoimmunity to OMGP in an animal model, we found that OMGP-specific T cells induce a novel type of experimental autoimmune encephalomyelitis dominated by meningitis above the cortical convexities. This unusual localization may be directed by intrathecal uptake and presentation of OMGP by meningeal phagocytes. Together, OMGP-directed autoimmunity provides a new element of heterogeneity, helping to improve the stratification of patients for diagnostic and therapeutic purposes.

The tremendous heterogeneity of the human population presents a major obstacle in understanding how autoimmune diseases like multiple sclerosis (MS) contribute to variations in human peripheral immune signatures. To minimize heterogeneity, we made use of a unique cohort of 43 monozygotic twin pairs clinically discordant for MS and searched for disease-related peripheral immune signatures in a systems biology approach covering a broad range of adaptive and innate immune populations on the protein level. Despite disease discordance, the immune signatures of MS-affected and unaffected cotwins were remarkably similar. Twinship alone contributed 56% of the immune variation, whereas MS explained 1 to 2% of the immune variance. Notably, distinct traits in CD4 + effector T cell subsets emerged when we focused on a subgroup of twins with signs of subclinical, prodromal MS in the clinically healthy cotwin. Some of these early-disease immune traits were confirmed in a second independent cohort of untreated early relapsing-remitting MS patients. Early involvement of effector T cell subsets thus points to a key role of T cells in MS disease initiation., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)

Multiple sclerosis (MS) is a disabling disease of the CNS. Inflammatory features of MS include lymphocyte accumulations in the CNS and cerebrospinal fluid (CSF). The preclinical events leading to established MS are still enigmatic. Here we compared gene expression patterns of CSF cells from MS-discordant monozygotic twin pairs. Six "healthy" co-twins, who carry a maximal familial risk for developing MS, showed subclinical neuroinflammation (SCNI) with small MRI lesions. Four of these subjects had oligoclonal bands (OCBs). By single-cell RNA sequencing of 2752 CSF cells, we identified clonally expanded CD8+ T cells, plasmablasts, and, to a lesser extent, CD4+ T cells not only from MS patients but also from subjects with SCNI. In contrast to nonexpanded T cells, clonally expanded T cells showed characteristics of activated tissue-resident memory T (TRM) cells. The TRM-like phenotype was detectable already in cells from SCNI subjects but more pronounced in cells from patients with definite MS. Expanded plasmablast clones were detected only in MS and SCNI subjects with OCBs. Our data provide evidence for very early concomitant activation of 3 components of the adaptive immune system in MS, with a notable contribution of clonally expanded TRM-like CD8+ cells.

Objective: CD8 + T cells are the most prevailing lymphocyte population in inflammatory lesions of patients with multiple sclerosis (MS) but it is not even known whether they are merely passive bystanders or actively communicate with other cells in the brain. To identify their potential interaction partners, we analyzed CD8 + T cells that contained vectorially oriented cytotoxic granules and analyzed the areas to which the granules pointed., Methods: We stained cryo-sections of active MS lesions of an index patient with antibodies to CD8 and perforin, searched for vectorially oriented perforin granules, and isolated target areas opposing the granules and control areas by laser-microdissection. From both areas, we analyzed cell-type specific transcripts by next-generation sequencing. In parallel, we stained samples from the index-patient and other patients by four-color immunohistochemistry (IHC)., Results: We found transcripts of the mononuclear phagocyte (MP) specific markers CD163 and CD11b only in the microdissected target areas but not in control areas. We validated the finding that MPs are communication partners of CD8 + T cells in MS lesions by classical IHC in samples from the index-patient and other patients with acute and progressive MS and other inflammatory neurological diseases., Interpretation: Because CD163 and CD11b are specifically expressed in MPs, our findings suggest that CD8 + T cells communicate with local MPs. Although it is still unclear if these interactions lead to killing of the communication partners by CD8 + T cells, our data underline that CD8 + T cells play an active role in the pathogenesis of MS., (© 2019 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals, Inc on behalf of American Neurological Association.)

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system with a modest concordance rate in monozygotic twins, which strongly argues for involvement of epigenetic factors. We observe highly similar peripheral blood mononuclear cell-based methylomes in 45 MS-discordant monozygotic twins. Nevertheless, we identify seven MS-associated differentially methylated positions (DMPs) of which we validate two, including a region in the TMEM232 promoter and ZBTB16 enhancer. In CD4 + T cells we find an MS-associated differentially methylated region in FIRRE. Additionally, 45 regions show large methylation differences in individual pairs, but they do not clearly associate with MS. Furthermore, we present epigenetic biomarkers for current interferon-beta treatment, and extensive validation shows that the ZBTB16 DMP is a signature for prior glucocorticoid treatment. Taken together, this study represents an important reference for epigenomic MS studies, identifies new candidate epigenetic markers, and highlights treatment effects and genetic background as major confounders.

Since the introduction of the interferons in the 1990s, a multitude of different immunomodulatory and immunosuppressant disease-modifying therapies for multiple sclerosis (MS) have been developed. They have all shown positive effects on clinical endpoints such as relapse rate and disease progression and are a heterogeneous group of therapeutics comprising recombinant pegylated and non-pegylated interferon-β variants, peptide combinations, monoclonal antibodies, and small molecules. However, they have relevant side effect profiles, which necessitate thorough monitoring and straightforward patient education. In individual cases, side effects can be severe and potentially life-threatening, which is why knowledge about (neurological and non-neurological) adverse drug reactions is essential for prescribing neurologists as well as general practitioners. This paper aims to provide an overview of currently available MS therapies, their modes of action and safety profiles, and the necessary therapy monitoring.

Background: The course of multiple sclerosis (MS) shows substantial inter-individual variability. The underlying determinants of disease severity likely involve genetic and environmental factors., Objective: The aim of this study was to assess the impact of APOE and HLA polymorphisms as well as smoking and body mass index (BMI) in the very early MS course., Methods: Untreated patients ( n = 263) with a recent diagnosis of relapsing-remitting (RR) MS or clinically isolated syndrome underwent standardized magnetic resonance imaging (MRI). Genotyping was performed for single-nucleotide polymorphisms (SNPs) rs3135388 tagging the HLA-DRB1*15:01 haplotype and rs7412 (Ɛ2) and rs429358 (Ɛ4) in APOE. Linear regression analyses were applied based on the three SNPs, smoking and BMI as exposures and MRI surrogate markers for disease severity as outcomes., Results: Current smoking was associated with reduced gray matter fraction, lower brain parenchymal fraction and increased cerebrospinal fluid fraction in comparison to non-smoking, whereas no effect was observed on white matter fraction. BMI and the SNPs in HLA and APOE were not associated with structural MRI parameters., Conclusions: Smoking may have an unfavorable effect on the gray matter fraction as a potential measure of MS severity already in early MS. These findings may impact patients' counseling upon initial diagnosis of MS.

There is emerging evidence that the commensal microbiota has a role in the pathogenesis of multiple sclerosis (MS), a putative autoimmune disease of the CNS. Here, we compared the gut microbial composition of 34 monozygotic twin pairs discordant for MS. While there were no major differences in the overall microbial profiles, we found a significant increase in some taxa such as Akkermansia in untreated MS twins. Furthermore, most notably, when transplanted to a transgenic mouse model of spontaneous brain autoimmunity, MS twin-derived microbiota induced a significantly higher incidence of autoimmunity than the healthy twin-derived microbiota. The microbial profiles of the colonized mice showed a high intraindividual and remarkable temporal stability with several differences, including Sutterella , an organism shown to induce a protective immunoregulatory profile in vitro. Immune cells from mouse recipients of MS-twin samples produced less IL-10 than immune cells from mice colonized with healthy-twin samples. IL-10 may have a regulatory role in spontaneous CNS autoimmunity, as neutralization of the cytokine in mice colonized with healthy-twin fecal samples increased disease incidence. These findings provide evidence that MS-derived microbiota contain factors that precipitate an MS-like autoimmune disease in a transgenic mouse model. They hence encourage the detailed search for protective and pathogenic microbial components in human MS., Competing Interests: The authors declare no conflict of interest.

Background: Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system. There are at least 150 000 persons with MS in Germany. Recent years have seen the approval of new drugs against., Methods: This article is based on pertinent literature retrieved by a selective search in PubMed as well as on documentation of relevant risks and adverse effects in "red hand letters" (information bulletins from pharmaceutical companies to physicians about adverse drug effects) and elsewhere, along with data provided by the German Multiple Sclerosis Competence Network., Results: In recent years, there have been major advances enabling better, more individualized treatment of patients with MS. Physicians must, however, give due consideration to potentially severe or even life-threatening adverse drug effects. These can include, for example, transaminase elevation (hepatotoxicity), cardio- and nephrotoxicity, or lympho- and leukopenia with a variable risk of infection. Among patients taking natalizumab, the cumulative risk of developing progressive multifocal leukencephalopathy (PML) may be 1:100 or higher, depending on the individual risk profile. Rare cases of PML have also been seen under treatment with fingolimod and dimethyl fumarate. Moreover, any type of immunosuppressive treatment can, at least theoretically, increase the risk of malignant disease. Secondary autoimmune diseases can arise as well: approximately 35% of patients treated with alemtuzumab develop autoimmune thyroid disease within two years, and 2% of patients who take daclizumab have severe autoimmune dermatological side effects. Teriflunomide, fingolimod, natalizumab, mitoxantrone, interferon β1-a/b, and daclizumab can all damage the liver. There are also psychiatric, reproductive, and vaccineassociated risks and side effects that must be considered., Conclusion: Newer drugs for MS have enabled more effective treatment, but are also associated with a higher risk of side effects. Interdisciplinary risk management is needed.

We investigated a patient who developed multiple sclerosis (MS) during treatment with the CTLA4-blocking antibody ipilimumab for metastatic melanoma. Initially he showed subclinical magnetic resonance imaging (MRI) changes (radiologically isolated syndrome). Two courses of ipilimumab were each followed by a clinical episode of MS, 1 of which was accompanied by a massive increase of MRI activity. Brain biopsy confirmed active, T-cell type MS. Quantitative next generation sequencing of T-cell receptor genes revealed distinct oligoclonal CD4(+) and CD8(+) T-cell repertoires in the primary melanoma and cerebrospinal fluid. Our results pinpoint the coinhibitory molecule CTLA4 as an immunological checkpoint and therapeutic target in MS. Ann Neurol 2016;80:294-300., (© 2016 The Authors. Annals of Neurology published by Wiley Periodicals, Inc. on behalf of American Neurological Association.)

We examined the debated link between mitochondrial DNA (mtDNA) variation and multiple sclerosis (MS) using 49 monozygotic (MZ) twin pairs clinically discordant for MS, which enables to associate de novo mtDNA variants, skewed heteroplasmy, and mtDNA copy number with MS manifestation. Ultra-deep sequencing of blood-derived mtDNA revealed 25 heteroplasmic variants with potentially pathogenic features in 18 pairs. All variants were pair-specific and had low and/or similar heteroplasmy levels in both cotwins. In one pair, a confirmed pathogenic variant (m.11778G>A, heteroplasmy ∼50%) associated with Leber hereditary optic neuropathy was detected. Detailed diagnostic investigation revealed subclinical MS signs in the prior nondiseased cotwin. Moreover, neither mtDNA deletions nor copy-number variations were involved. Furthermore, the majority of heteroplasmic variants were shared among MZ twins and exhibited more similar heteroplasmy levels in the same tissue of MZ twins as compared with different tissues of the same individual. Heteroplasmy levels were also more similar within MZ twins compared with nonidentical siblings. Our analysis excludes mtDNA variation as a major driver of the discordant clinical manifestation of MS in MZ twins, and provides valuable insights into the occurrence and distribution of heteroplasmic variants within MZ twins and nonidentical siblings, and across different tissues., (© 2016 WILEY PERIODICALS, INC.)

Oligoclonal Ig bands (OCBs) of the cerebrospinal fluid are a hallmark of multiple sclerosis (MS), a disabling inflammatory disease of the central nervous system (CNS). OCBs are locally produced by clonally expanded antigen-experienced B cells and therefore are believed to hold an important clue to the pathogenesis. However, their target antigens have remained unknown, mainly because it was thus far not possible to isolate distinct OCBs against a background of polyclonal antibodies. To overcome this obstacle, we copurified disulfide-linked Ig heavy and light chains from distinct OCBs for concurrent analysis by mass spectrometry and aligned patient-specific peptides to corresponding transcriptome databases. This method revealed the full-length sequences of matching chains from distinct OCBs, allowing for antigen searches using recombinant OCB antibodies. As validation, we demonstrate that an OCB antibody from a patient with an infectious CNS disorder, neuroborreliosis, recognized a Borrelia protein. Next, we produced six recombinant antibodies from four MS patients and identified three different autoantigens. All of them are conformational epitopes of ubiquitous intracellular proteins not specific to brain tissue. Our findings indicate that the B-cell response in MS is heterogeneous and partly directed against intracellular autoantigens released during tissue destruction. In addition to helping elucidate the role of B cells in MS, our approach allows the identification of target antigens of OCB antibodies in other neuroinflammatory diseases and the production of therapeutic antibodies in infectious CNS diseases.

Background: Natalizumab treatment is associated with progressive multifocal leukoencephalopathy (PML) development. Treatment duration, prior immunosuppressant use, and JCV serostatus are currently used for risk stratification, but PML incidence stays high. Anti-JCV antibody index and L-selectin (CD62L) have been proposed as additional risk stratification parameters., Objective: This study aimed at verifying and integrating both parameters into one algorithm for risk stratification., Methods: Multicentric, international cohorts of natalizumab-treated MS patients were assessed for JCV index (1921 control patients and nine pre-PML patients) and CD62L (1410 control patients and 17 pre-PML patients)., Results: CD62L values correlate with JCV serostatus, as well as JCV index values. Low CD62L in natalizumab-treated patients was confirmed and validated as a biomarker for PML risk with the risk factor "CD62L low" increasing a patient's relative risk 55-fold (p < 0.0001). Validation efforts established 86% sensitivity/91% specificity for CD62L and 100% sensitivity/59% specificity for JCV index as predictors of PML. Using both parameters identified 1.9% of natalizumab-treated patients in the reference center as the risk group., Conclusions: Both JCV index and CD62L have merit for risk stratification and share a potential biological relationship with implications for general PML etiology. A risk algorithm incorporating both biomarkers could strongly reduce PML incidence., (© The Author(s), 2015.)

With the approval of various substances for the immunotherapy of multiple sclerosis (MS), treatment possibilities have improved significantly over the last few years. Indeed, the choice of individually tailored preparations and treatment monitoring for the treating doctor is becoming increasingly more complex. This is particularly applicable for monitoring for a treatment-induced compromise of the immune system. The following article by members of the German Multiple Sclerosis Skills Network (KKNMS) and the task force "Provision Structures and Therapeutics" summarizes the practical recommendations for approved immunotherapy for mild to moderate and for (highly) active courses of MS. The focus is on elucidating the substance-specific relevance of particular laboratory parameters with regard to the mechanism of action and the side effects profile. To enable appropriate action to be taken in clinical practice, any blood work changes that can be expected, in addition to any undesirable laboratory findings and their causes and relevance, should be elucidated.

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system (CNS) resulting from a breakdown in peripheral immune tolerance. Although a beneficial role of natural killer (NK)-cell immune-regulatory function has been proposed, it still needs to be elucidated whether NK cells are functionally impaired as part of the disease. We observed NK cells in active MS lesions in close proximity to T cells. In accordance with a higher migratory capacity across the blood-brain barrier, CD56(bright) NK cells represent the major intrathecal NK-cell subset in both MS patients and healthy individuals. Investigating the peripheral blood and cerebrospinal fluid of MS patients treated with natalizumab revealed that transmigration of this subset depends on the α4β1 integrin very late antigen (VLA)-4. Although no MS-related changes in the migratory capacity of NK cells were observed, NK cells derived from patients with MS exhibit a reduced cytolytic activity in response to antigen-activated CD4(+) T cells. Defective NK-mediated immune regulation in MS is mainly attributable to a CD4(+) T-cell evasion caused by an impaired DNAX accessory molecule (DNAM)-1/CD155 interaction. Both the expression of the activating NK-cell receptor DNAM-1, a genetic alteration consistently found in MS-association studies, and up-regulation of the receptor's ligand CD155 on CD4(+) T cells are reduced in MS. Therapeutic immune modulation of IL-2 receptor restores impaired immune regulation in MS by increasing the proportion of CD155-expressing CD4(+) T cells and the cytolytic activity of NK cells.

Interest in CD8+ T cells and B cells was initially inspired by observations in multiple sclerosis rather than in animal models: CD8+ T cells predominate in multiple sclerosis lesions, oligoclonal immunoglobulin bands in CSF have long been recognised as diagnostic and prognostic markers, and anti-B-cell therapies showed considerable efficacy in multiple sclerosis. Taking a reverse-translational approach, findings from human T-cell receptor (TCR) and B-cell receptor (BCR) repertoire studies provided strong evidence for antigen-driven clonal expansion in the brain and CSF. New methods allow the reconstruction of human TCRs and antibodies from tissue-infiltrating immune cells, which can be used for the unbiased screening of antigen libraries. Myelin oligodendrocyte glycoprotein (MOG) has received renewed attention as an antibody target in childhood multiple sclerosis and in a small subgroup of adult patients with multiple sclerosis. Furthermore, there is growing evidence that a separate condition in adults exists, tentatively called MOG-antibody-associated encephalomyelitis, which has clinical features that overlap with neuromyelitis optica spectrum disorder and multiple sclerosis. Although CD8+ T cells and B cells are thought to have a pathogenic role in some subgroups of patients, their target antigens have yet to be identified., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Identification of the target antigens of pathogenic antibodies and T cells is of fundamental importance for understanding the pathogenesis of multiple sclerosis, and for the development of personalised treatments for the disease. Myelin-specific CD4+ T cells emerged long ago as a key player in animal models of multiple sclerosis. Taking a forward-translational approach, autoreactive CD4+ T cells have been studied extensively in patients with multiple sclerosis, and there is evidence, but as yet no direct proof, that autoreactive CD4+ T cells are a key player in the pathogenesis of the disorder. Several therapies that selectively target myelin-specific CD4+ T cells have been investigated in clinical trials up to phase 3. So far, however, none of these (mostly underpowered) therapeutic trials have provided definitive evidence of clinical efficacy. One major obstacle to personalised, highly selective immunotherapy is the absence of standardised and reliable assays to assess antigen-specific human T-cell responses. Such assays would be essential for stratification of patients with multiple sclerosis according to their individual target antigens., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Immunoglobulin G (IgG) effector functions are regulated by the composition of glycans attached to a conserved N-glycosylation site in the Fc part. Intrathecal production of IgG, especially IgG1, is a hallmark of multiple sclerosis (MS), but nothing is known about IgG Fc glycosylation in MS and in cerebrospinal fluid (CSF) in general., Methods: We applied mass spectrometry of tryptic Fc glycopeptides to analyze IgG Fc glycosylation (sialylation, galactosylation, fucosylation, and bisecting N-acetylglucosamine (GlcNAc)) in 48 paired CSF and serum samples from adult patients with MS or a first demyelinating event highly suggestive of MS (designated as MS cases), and from healthy volunteers and patients with other non-inflammatory diseases (control group). p values were adjusted for multiple testing., Results: Our experiments revealed four main results. First, IgG1 glycosylation patterns were different in CSF vs. serum, in the MS group and even in control donors without intrathecal IgG synthesis. Second, in MS patients vs. controls, IgG1 glycosylation patterns were altered in CSF, but not in serum. Specifically, in CSF from the MS group, bisecting GlcNAc were elevated, and afucosylation and galactosylation were reduced. Elevated bisecting GlcNAc and reduced galactosylation are known to enhance IgG effector functions. Third, hypothesis-free regression analysis revealed that alterations of afucosylation and bisecting GlcNAc in CSF from MS cases peaked 2-3 months after the last relapse. Fourth, CSF IgG1 glycosylation correlated with the degree of intrathecal IgG synthesis and CSF cell count., Conclusions: The CNS compartment as well as the inflammatory milieu in MS affect IgG1 Fc glycosylation. In MS, the CSF IgG1 glycosylation has features that enhance Fc effector functions.

In recent years the approval of new substances has led to a substantial increase in the number of course-modifying immunotherapies available for multiple sclerosis. Therapy conversion therefore represents an increasing challenge. The treatment options sometimes show complex adverse effect profiles and necessitate a long-term and comprehensive monitoring. This article presents an overview of therapy conversion of immunotherapies for multiple sclerosis in accordance with the recommendations of the Disease-Related Competence Network for Multiple Sclerosis and the German Multiple Sclerosis Society as well as the guidelines on diagnostics and therapy for multiple sclerosis of the German Society of Neurology and the latest research results. At the present point in time it should be noted that no studies have been carried out for most of the approaches for therapy conversion given here; however, the recommendations are based on theoretical considerations and therefore correspond to recommendations at the level of expert consensus, which is currently essential for the clinical daily routine.

The individual risk of contracting multiple sclerosis (MS) is determined by genetic predisposition as well as environmental factors. In monozygotic twins the concordance rate for MS is approximately 30 % indicating that environmental factors are even more important than genetic factors. Observations in a T-cell receptor-transgenic, spontaneous mouse model strongly point to an important contribution of the individual gut microbiome (microbiota). Mice maintained in a germ-free environment are completely protected from experimental autoimmune encephalomyelitis (EAE) in this model, whereas mice that are kept under normal conditions spontaneously develop a relapsing-remitting central nervous system (CNS) disease which is astoundingly similar to human MS. It appears that the autoimmune reaction against CNS tissue is "remotely controlled" by the gut microbiota. This may be explained by the facts that the microbiota influences the gut-associated lymphoid tissue (GALT) and, vice versa, the GALT regulates systemic immunity. The precise role of the microbiota in MS remains to be clarified. New methods of DNA sequencing and bioinformatics allow the analysis of very complex bacterial metagenomes. If individual microbial risk profiles can be identified this would provide completely new perspectives for the prophylaxis and therapy of MS.

Background: Natalizumab for multiple sclerosis (MS) increases the risk of progressive multifocal leukoencephalopathy (PML)., Objective: We aimed to assess the effect of natalizumab on cellular composition and functional B cell parameters including patients with natalizumab-associated PML (n=37)., Methods: Cellular composition by flow cytometry, levels of immunoglobulin (Ig)G/IgM by immunonephelometry, and oligoclonal bands by isoelectric focusing were studied in blood and cerebrospinal fluid., Results: In MS patients treated with natalizumab without PML (n=59) the proportion of CD19+ B cells was higher in blood, but lower in cerebrospinal fluid compared with MS patients not treated with natalizumab (n=17). The CD4/CD8-ratio in cerebrospinal fluid was lower, and IgG and IgM levels as well as the IgG index dropped in longitudinal samples during natalizumab therapy. Oligoclonal bands persisted, but the total amount of the intrathecally produced IgG fraction, and the polyclonal intrathecal IgG reactivity to measles, rubella, and zoster declined. At the time of diagnosis of PML patients with natalizumab-associated PML had low total IgG levels in blood and cerebrospinal fluid., Conclusions: Natalizumab impacts B and T cell distribution and exerts an inhibitory effect on surrogates of B cell function in periphery and in cerebrospinal fluid, potentially contributing to the increased risk of developing PML., (© The Author(s), 2014.)

Multiple sclerosis (MS) is an inflammatory, presumably autoimmune disease affecting the central nervous system. Early stages of the disease are characterized by conspicuous inflammation of the white and grey matter. During later stages, presumably secondary neurodegeneration leads to physical disability progression. Over the last decade increasingly effective therapeutic options have been approved. Currently 11 immunomodulatory or immunosuppressive therapies targeting relapse rate, disease progression and paraclinical disease activity are available, mostly for relapsing forms of MS. However, the ideal of "precision medicine" is still in the distant future since biomarkers for individualized treatment are lacking. For implementation of risk-management plans to minimize the risk of severe side effects, interdisciplinary collaboration between neurologists and internists is essential. In this review article we summarize practical aspects of the implemented risk-management plans, and discuss possible side effects and special caveats of the three new immunotherapies teriflunomide, dimethyl fumarate, and alemtuzumab. This article is based on, among others, the recently updated guidelines of the German Society of Neurology. Particular attention is given to the risks of new therapies, monitoring, and on special aspects needing attention when changing treatments. Teriflunomide, dimethyl fumarate, and alemtuzumab expand treatment options for relapsing-remitting MS. Treatment selection should take into consideration the safety profile of the substance, previous and concomitant diseases, and other individual factors. This requires in-depth consultation and individual assessment of current disease activity, the potential efficacy of the therapy, and the possible risks and side effects.

BAFF and a proliferation-inducing ligand (APRIL), which control B cell homeostasis, are therapeutic targets in autoimmune diseases. TACI-Fc (atacicept), a soluble fusion protein containing the extracellular domain of the BAFF-APRIL receptor TACI, was applied in clinical trials. However, disease activity in multiple sclerosis unexpectedly increased, whereas in systemic lupus erythematosus, atacicept was beneficial. In this study, we show that an endogenous soluble TACI (sTACI) exists in vivo. TACI proteolysis involved shedding by a disintegrin and metalloproteinase 10 releasing sTACI from activated B cells. The membrane-bound stub was subsequently cleaved by γ-secretase reducing ligand-independent signaling of the remaining C-terminal fragment. The shed ectodomain assembled ligand independently in a homotypic way. It functioned as a decoy receptor inhibiting BAFF- and APRIL-mediated B cell survival and NF-κB activation. We determined sTACI levels in autoimmune diseases with established hyperactivation of the BAFF-APRIL system. sTACI levels were elevated both in the cerebrospinal fluid of the brain-restricted autoimmune disease multiple sclerosis correlating with intrathecal IgG production, as well as in the serum of the systemic autoimmune disease systemic lupus erythematosus correlating with disease activity. Together, we show that TACI is sequentially processed by a disintegrin and metalloproteinase 10 and γ-secretase. The released sTACI is an immunoregulator that shares decoy functions with atacicept. It reflects systemic and compartmentalized B cell accumulation and activation., (Copyright © 2015 by The American Association of Immunologists, Inc.)

Chronic demyelination is a pathological hallmark of multiple sclerosis (MS). Only a minority of MS lesions remyelinates completely. Enhancing remyelination is, therefore, a major aim of future MS therapies. Here we took a novel approach to identify factors that may inhibit or support endogenous remyelination in MS. We dissected remyelinated, demyelinated active, and demyelinated inactive white matter MS lesions, and compared transcript levels of myelination and inflammation-related genes using quantitative PCR on customized TaqMan Low Density Arrays. In remyelinated lesions, fibroblast growth factor (FGF) 1 was the most abundant of all analyzed myelination-regulating factors, showed a trend towards higher expression as compared to demyelinated lesions and was significantly higher than in control white matter. Two MS tissue blocks comprised lesions with adjacent de- and remyelinated areas and FGF1 expression was higher in the remyelinated rim compared to the demyelinated lesion core. In functional experiments, FGF1 accelerated developmental myelination in dissociated mixed cultures and promoted remyelination in slice cultures, whereas it decelerated differentiation of purified primary oligodendrocytes, suggesting that promotion of remyelination by FGF1 is based on an indirect mechanism. The analysis of human astrocyte responses to FGF1 by genome wide expression profiling showed that FGF1 induced the expression of the chemokine CXCL8 and leukemia inhibitory factor, two factors implicated in recruitment of oligodendrocytes and promotion of remyelination. Together, this study presents a transcript profiling of remyelinated MS lesions and identified FGF1 as a promoter of remyelination. Modulation of FGF family members might improve myelin repair in MS.

Multiple sclerosis (MS), a demyelinating disease of the central nervous system (CNS), presents as a complex disease with variable clinical and pathological manifestations, involving different pathogenic pathways. Animal models, particularly experimental autoimmune encephalomyelitis (EAE), have been key to deciphering the pathophysiology of MS, although no single model can recapitulate the complexity and diversity of MS, or can, to date, integrate the diverse pathogenic pathways. Since the first EAE model was introduced decades ago, multiple classic (induced), spontaneous, and humanized EAE models have been developed, each recapitulating particular aspects of MS pathogenesis. The advances in technologies of genetic ablation and transgenesis in mice of C57BL/6J background and the development of myelin-oligodendrocyte glycoprotein (MOG)-induced EAE in C57BL/6J mice yielded several spontaneous and humanized EAE models, and resulted in a plethora of EAE models in which the role of specific genes or cell populations could be precisely interrogated, towards modeling specific pathways of MS pathogenesis/regulation in MS. Collectively, the numerous studies on the different EAE models contributed immensely to our basic understanding of cellular and molecular pathways in MS pathogenesis as well as to the development of therapeutic agents: several drugs available today as disease modifying treatments were developed from direct studies on EAE models, and many others were tested or validated in EAE. In this review, we discuss the contribution of major classic, spontaneous, and humanized EAE models to our understanding of MS pathophysiology and to insights leading to devising current and future therapies for this disease., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Intrathecal oligoclonal bands of the cerebrospinal fluid are considered the most important immunological biomarkers of multiple sclerosis. They typically consist of clonally expanded IgG antibodies that underwent affinity maturation during sustained stimulation by largely unknown antigens. In addition, ∼40% of patients with multiple sclerosis have oligoclonal bands that consist of expanded IgM antibodies. We investigated the molecular composition of IgM- and IgG-chains from cerebrospinal fluid of 12 patients with multiple sclerosis, seven patients with other neurological diseases, and eight healthy control subjects by high-throughput deep-sequencing and single-cell PCR. Further, we studied the expression of activation-induced cytidine deaminase, the key enzyme for affinity maturation of antibodies, in cerebrospinal fluid samples of 16 patients. From the cerebrospinal fluid of two multiple sclerosis patients we isolated single B cells and investigated the co-expression of antibody chains with activation-induced cytidine deaminase. In striking contrast to IgM-chains from peripheral blood, IgM-chains from cerebrospinal fluid of patients with multiple sclerosis or neuroborreliosis showed a high degree of somatic hypermutation. We found a high content of mutations that caused amino acid exchanges as compared to silent mutations. In addition, more mutations were found in the complementarity determining regions of the IgM-chains, which interact with yet unknown antigens, as compared to framework regions. Both observations provide evidence for antigen-driven affinity maturation. Furthermore, single B cells from the cerebrospinal fluid of patients with multiple sclerosis co-expressed somatically hypermutated IgM-chains and activation-induced cytidine deaminase, an enzyme that is crucial for somatic hypermutation and class switch recombination of antibodies and is normally expressed during activation of B cells in germinal centres. Clonal tracking of particular IgM(+) B cells allowed us to relate unmutated ancestor clones in blood to hypermutated offspring clones in CSF. Unexpectedly, however, we found no evidence for intrathecal isotype switching from IgM to IgG. Our data suggest that the intrathecal milieu sustains a germinal centre-like reaction with clonal expansion and extensive accumulation of somatic hypermutation in IgM-producing B cells., (© The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

After discontinuation of natalizumab (NAT), multiple sclerosis (MS) disease activity often recurs. We assessed the recurrence of clinical disease activity during the first year after switching from NAT to fingolimod (FTY) in patients with relapsing-remitting MS. The number of relapses and the annualized relapse rate (ARR) before, during and after NAT discontinuation were determined and compared between 26 MS patients who switched to FTY within 24 weeks, and 10 MS patients who remained without disease modifying therapy (therapy free group = TFG). Median follow-up post-NAT discontinuation was 55.1 weeks. In a subgroup (n = 20), the occurrence of contrast-enhancing-lesions (Gd+) on magnetic resonance imaging (MRI) was determined. Eleven patients (42 %) in the FTY group and seven patients (70 %) in the TFG had one or more relapses after cessation of NAT during follow-up (p < 0.05). One of the 11 (9 %) patients in the FTY group and 6/9 (67 %) patients in the TFG showed Gd+ lesions during follow-up (p < 0.05). Patients who switched to FTY ≤ 12 weeks after NAT discontinuation (n = 9) showed a trend for a lower post-NAT ARR compared to patients who started FTY therapy >12 weeks after NAT was stopped (n = 17). Most relapses in the FTY group occurred just before or within 8 weeks after starting FTY. Our observation suggests that initiation of FTY treatment after NAT discontinuation reduces the recurrence of disease activity compared to withdrawal without further immunomodulatory treatment. In the FTY group the ARR tended to depend on the time interval between discontinuation of NAT and initiation of FTY.

In recent years, multiple sclerosis (MS) research has progressed on several fronts, prompting numerous clinical trials, primarily for immunotherapeutics. Although several new therapies have been disappointing and some were revealed to have devastating side effects, others have shown benefits and all have generated valuable knowledge about the progression of MS, the key contributors to pathogenesis, and on natural surveillance mechanisms for brain infections. This makes now a useful time to take stock of recent advances in developing MS treatments and consider new approaches for adding information where the gaps are greatest - mainly in understanding the degenerative processes responsible for most of the long-term disability. Here, we summarize currently accepted therapeutic principles and the drugs in late stages of development, as well as spotlighting potential novel openings for future research., (Copyright © 2013 Elsevier Ltd. All rights reserved.)