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Background and ObjectivesThe B cell–depleting anti-CD20 antibody ocrelizumab (OCR) effectively reduces MS disease activity and slows disability progression. Given the role of B cells as antigen-presenting cells, the primary goal of this study was to evaluate the effect of OCR on the T-cell receptor repertoire diversity.MethodsTo examine whether OCR substantially alters the molecular diversity of the T-cell receptor repertoire, deep immune repertoire sequencing (RepSeq) of CD4+and CD8+T-cell receptor β-chain variable regions was performed on longitudinal blood samples. The IgM and IgG heavy chain variable region repertoire was also analyzed to characterize the residual B-cell repertoire under OCR treatment.ResultsPeripheral blood samples for RepSeq were obtained from 8 patients with relapsing MS enrolled in the OPERA I trial over a period of up to 39 months. Four patients each were treated with OCR or interferon β1-a during the double-blind period of OPERA I. All patients received OCR during the open-label extension. The diversity of the CD4+/CD8+T-cell repertoires remained unaffected in OCR-treated patients. The expected OCR-associated B-cell depletion was mirrored by reduced B-cell receptor diversity in peripheral blood and a shift in immunoglobulin gene usage. Despite deep B-cell depletion, longitudinal persistence of clonally related B-cells was observed.DiscussionOur data illustrate that the diversity of CD4+/CD8+T-cell receptor repertoires remained unaltered in OCR-treated patients with relapsing MS. Persistence of a highly diverse T-cell repertoire suggests that aspects of adaptive immunity remain intact despite extended anti-CD20 therapy.Trial Registration InformationThis is a substudy (BE29353) of the OPERA I (WA21092;NCT01247324) trial. Date of registration, November 23, 2010; first patient enrollment, August 31, 2011.

Although B cells are implicated in multiple sclerosis (MS) pathophysiology, a predictive or diagnostic autoantibody remains elusive. Here, the Department of Defense Serum Repository (DoDSR), a cohort of over 10 million individuals, was used to generate whole-proteome autoantibody profiles of hundreds of patients with MS (PwMS) years before and subsequently after MS onset. This analysis defines a unique cluster of PwMS that share an autoantibody signature against a common motif that has similarity with many human pathogens. These patients exhibit antibody reactivity years before developing MS symptoms and have higher levels of serum neurofilament light (sNfL) compared to other PwMS. Furthermore, this profile is preserved over time, providing molecular evidence for an immunologically active prodromal period years before clinical onset. This autoantibody reactivity was validated in samples from a separate incident MS cohort in both cerebrospinal fluid (CSF) and serum, where it is highly specific for patients eventually diagnosed with MS. This signature is a starting point for further immunological characterization of this MS patient subset and may be clinically useful as an antigen-specific biomarker for high-risk patients with clinically- or radiologically-isolated neuroinflammatory syndromes.

A small proportion of multiple sclerosis (MS) patients develop new disease activity soon after starting anti-CD20 therapy. This activity does not recur with further dosing, possibly reflecting deeper depletion of CD20-expressing cells with repeat infusions. We assessed cellular immune profiles and their association with transient disease activity following anti-CD20 initiation as a window into relapsing disease biology. Peripheral blood mononuclear cells from independent discovery and validation cohorts of MS patients initiating ocrelizumab were assessed for phenotypic and functional profiles using multiparametric flow cytometry. Pretreatment CD20-expressing T cells, especially CD20 dim CD8 + T cells with a highly inflammatory and central nervous system (CNS)-homing phenotype, were significantly inversely correlated with pretreatment MRI gadolinium-lesion counts, and also predictive of early disease activity observed after anti-CD20 initiation. Direct removal of pretreatment proinflammatory CD20 dim CD8 + T cells had a greater contribution to treatment-associated changes in the CD8 + T cell pool than was the case for CD4 + T cells. Early disease activity following anti-CD20 initiation was not associated with reconstituting CD20 dim CD8 + T cells, which were less proinflammatory compared with pretreatment. Similarly, this disease activity did not correlate with early reconstituting B cells, which were predominantly transitional CD19 + CD24 high CD38 high with a more anti-inflammatory profile. We provide insights into the mode-of-action of anti-CD20 and highlight a potential role for CD20 dim CD8 + T cells in MS relapse biology; their strong inverse correlation with both pretreatment and early posttreatment disease activity suggests that CD20-expressing CD8 + T cells leaving the circulation (possibly to the CNS) play a particularly early role in the immune cascades involved in relapse development.

This analysis evaluated long-term safety findings from the SAkuraSky and SAkuraStar studies with satralizumab in patients with neuromyelitis optica spectrum disorder (NMOSD).SAkuraSky (satralizumab in combination with baseline immunosuppressive therapy; IST) and SAkuraStar (satralizumab monotherapy) are international, multicenter, randomized, placebo-controlled, phase 3 studies consisting of a double-blind (DB) period followed by an open-label extension (OLE). The overall satralizumab treatment (OST) period safety population comprised patients receiving ≥1 dose of satralizumab in the DB and/or OLE periods (cut-off date: 22 February 2021). Safety was evaluated in the DB and OST periods.In the SAkuraSky DB period, patients received satralizumab (n = 41) or placebo (n = 42) in addition to stable baseline IST; 75 patients were included in the OST population. In the SAkuraStar DB period, 63 patients received satralizumab monotherapy and 32 received placebo; 91 patients were included in the OST population. Median treatment exposure in the OST period was 4.4 years (range 0.1-7.0) in SAkuraSky and 4.0 years (range 0.1-6.1) in SAkuraStar. Rates of adverse events (AEs per 100 patient-years) and serious AEs in the OST period were comparable with satralizumab and placebo in the DB periods of both studies. Similarly, overall rates of infections and serious infections were consistent between the OST and DB periods with satralizumab, with no increase in rates of infections or serious infections over time. In the OST periods, longer exposure to satralizumab was not associated with a higher risk of severe (grade ≥3) laboratory changes versus the DB periods. No deaths or anaphylactic reactions to treatment with satralizumab were reported during the OST periods of both studies.The safety profile of satralizumab as a monotherapy or in combination with IST was maintained in the OLE, and no new safety concerns versus the DB period were observed.ClinicalTrials.gov identifiers: NCT02028884 (SAkuraSky) and NCT02073279 (SAkuraStar).

Background and ObjectivesSatralizumab, an interleukin 6 receptor inhibitor, reduced the risk of protocol-defined relapse (PDR) vs placebo in 2 independent, double-blind studies in patients with neuromyelitis optica spectrum disorder (NMOSD). We assessed the long-term efficacy of satralizumab in patients with aquaporin-4-immunoglobulin G (IgG)–seropositive (AQP4-IgG+) NMOSD.MethodsFollowing the double-blind periods of SAkuraSky (satralizumab + baseline immunosuppressive treatment [IST]) and SAkuraStar (satralizumab monotherapy), patients could enter the open-label extension (OLE, satralizumab 120 mg Q4W ± IST). This analysis included all AQP4-IgG+ patients who received ≥1 dose of satralizumab in the double-blind and/or OLE periods, from patients' first dose to the data cutoff (February 22, 2021). PDR in the OLE period was determined by the investigator without external adjudication. We evaluated time to first investigator-reported PDR (iPDR), severe iPDR (≥2 point increase in the Expanded Disability Status Scale [EDSS] score), and sustained EDSS worsening (EDSS score increase of ≥2, ≥1, or ≥0.5 points for patients with baseline scores of 0, 1–5, or ≥5.5, respectively, confirmed ≥24 weeks post–initial worsening), plus the annualized iPDR rate (ARR).ResultsForty-six of 55 AQP4-IgG+ patients (84%) in SAkuraSky and 57/64 patients in SAkuraStar (89%) continued from the double-blind periods into the OLEs. In total, 111 AQP4-IgG+ patients received ≥1 dose of satralizumab in the double-blind and/or OLE periods and were included in these analyses (SAkuraSky: 49; SAkuraStar: 62). The median (range) duration of satralizumab exposure was 4.4 (0.1–7.0) years in SAkuraSky and 4.0 (0.1–6.0) years in SAkuraStar, with a combined 440.1 patient-years of treatment. Seventy-one of 111 patients (64%) received satralizumab for ≥192 weeks (3.7 years). At this time point, 71% (SAkuraSky) and 73% (SAkuraStar) of satralizumab-treated patients were free from iPDR, 91% (SAkuraSky) and 90% (SAkuraStar) were free from severe iPDR, and 90% (SAkuraSky) and 86% (SAkuraStar) had no sustained EDSS worsening. The overall adjusted ARR (95% CI) was 0.12 (0.08–0.18) in SAkuraSky and 0.08 (0.05–0.13) in SAkuraStar and remained stable over time.DiscussionThese long-term results from the OLE periods of the SAkura studies demonstrate the continued efficacy of satralizumab over more than 3.5 years of treatment. High proportions of patients remained free from relapse, severe relapse, or worsening disease, with a consistently low ARR.Trial Registration InformationClinicalTrials.gov registration numbers:NCT02028884(SAkuraSky) andNCT02073279(SAkuraStar).Classification of EvidenceThis study provides Class II evidence that satralizumab reduces the risk of relapse in patients with AQP4-IgG+ NMOSD beyond the first 96 weeks of treatment.

Background: Neurofilament light (NfL) chain is an established cerebrospinal fluid (CSF) biomarker for neuroaxonal injury. The highly sensitive Quanterix Simoa™ platform is evaluated for NfL measurement in both CSF and blood. There is a need to link historical ELISA data that use bovine NfL to that of Simoa using a recombinant human (rhuman) NfL standard. Results/Methodology: The Simoa NF-light® Advantage Kit was validated for CSF and qualified for serum and plasma, using both rhuman and bovine NfL calibrators. Matched CSF, serum and plasma samples from 112 multiple sclerosis patients were analyzed using both calibrators. Conclusion: In multiple sclerosis, there is a good correlation between blood and CSF NfL levels. A conversion factor of approximately 5:1 was established between bovine and rhuman NfL calibrators.

Background To date, no specific scales have been developed to explore the impact of neuromyelitis optica spectrum disorder (NMOSD)-related disability on quality of life (QoL). The Expanded Disability Status Scale (EDSS) and the EuroQol 5-dimensions (EQ-5D) have been used to assess disability and QoL, respectively, in patients with NMOSD. However, there is limited evidence surrounding their use in this condition. We compared EDSS and EQ-5D data across two clinical trials to quantify the relationship between disability and QoL in patients with NMOSD. Methods SAkuraSky (NCT02028884) and SAkuraStar (NCT02073279) were Phase 3, multicenter, randomized, international, double-blind, placebo-controlled, parallel-assignment studies of satralizumab, administered in combination with baseline immunosuppressants (SAkuraSky) or as monotherapy (SAkuraStar). EDSS and EQ-5D were assessed at baseline and at 24-week intervals thereafter. The relationship between disability and QoL was assessed by estimating EQ-5D utilities (UK tariff) for each incremental EDSS category. A repeated-measures linear model was used to regress health utilities on EDSS score-derived health states. Results Overall, 176 patients underwent at least one EDSS assessment and completed an EQ-5D survey and were included in this analysis. There was a clear association between mean EQ-5D score and EDSS score, with decreases in QoL being observed at each incremental increase in disability. The relationship between EDSS and EQ-5D score remained consistent across the different treatment groups. Conclusions These results, generated from high-quality clinical trial data, demonstrated a strong and consistent relationship between disability and QoL in patients with NMOSD.

Neuromyelitis optica spectrum disorder (NMOSD) is a rare, chronic, autoimmune disease, characterized by astrocytopathic lesions in the central nervous system (Beekman et al., 2019; Fujihara et al., 2020). The main aim of NMOSD maintenance therapy is to reduce the frequency and severity of relapses and minimize future disability (Fujihara et al., 2020). Oral corticosteroids are used long-term to prevent relapses, but are associated with serious complications (Kessler et al., 2016; Kimbrough et al., 2012). In the SAkuraSky study, satralizumab reduced the risk of relapse in patients with NMOSD compared with placebo, with comparable rates of serious adverse events and infections between treatment arms (Yamamura et al., 2019). Here, we report on 16 patients who tapered their steroid dose during the openlabel extension (OLE) period of SAkuraSky.SAkuraSky was a phase 3, multicenter, randomized, double-blind (DB), placebo-controlled study of satralizumab in combination with immunosuppressive therapies (ISTs) in patients with NMOSD. Patients were randomized 1:1 to receive 120 mg subcutaneous satralizumab or placebo in addition to a stable dose of their baseline IST. After completing the DB period or experiencing relapse, patients could enter the OLE period. In the OLE, all patients received satralizumab, and IST doses could be tapered at the investigator's discretion. We assessed the different steroid tapering patterns and their impact on relapse and safety. Patients were considered to have tapered their steroids if their steroid dose at the clinical cut-off date (CCOD: February 18, 2020) was lower than on the first day of the OLE. Annualized relapse rate (ARR) was calculated as the number of relapses divided by the total number of patientyears at risk.Overall, 36 patients receiving oral corticosteroids entered the OLE, of whom 16 tapered their steroid dose. The mean age (range) at baseline was 44.9 (16-73) years, all 16 were female, 14 (88%) were Japanese, and 15 (94%) were AQP4-IgG seropositive. None were receiving any additional ISTs. Patients tapered their steroids from a median of 10 (range: 5-25) mg/day at OLE baseline to 2.75 (0-15) mg/day at the CCOD. Three patients discontinued steroids entirely, and all three remained relapse free. One patient who remained relapse free had temporary increases in steroid dose. Three relapses were observed in two patients who tapered steroids during the OLE; all three relapses required treatment. One of the relapses occurred shortly after a drop in steroid dose from 25 to 10 mg/day. The ARR for steroid-tapered patients was numerically lower in the OLE period than the satralizumab group in the DB period. The safety profile of satralizumab was in line with the overall SAkuraSky population. Two serious infections were observed in steroid-tapered patients in the OLE, both in the same patient: one event (hepatitis E) occurred before the patient began tapering their steroid dose; and one event (influenza) occurred while the patient was tapering.During the OLE of SAkuraSky, 16 patients tapered steroids and the ARR did not increase from the DB period. Patient numbers limit interpretation.

ObjectiveTo study intrathecal B-cell activity in leucine-rich, glioma-inactivated 1 (LGI1) antibody encephalitis. In patients with LGI1 antibodies, the lack of CSF lymphocytosis or oligoclonal bands and serum-predominant LGI1 antibodies suggests a peripherally initiated immune response. However, it is unknown whether B cells within the CNS contribute to the ongoing pathogenesis of LGI1 antibody encephalitis.MethodsPaired CSF and peripheral blood (PB) mononuclear cells were collected from 6 patients with LGI1 antibody encephalitis and 2 patients with other neurologic diseases. Deep B-cell immune repertoire sequencing was performed on immunoglobulin heavy chain transcripts from CSF B cells and sorted PB B-cell subsets. In addition, LGI1 antibody levels were determined in CSF and PB.ResultsSerum LGI1 antibody titers were on average 127-fold higher than CSF LGI1 antibody titers. Yet, deep B-cell repertoire analysis demonstrated a restricted CSF repertoire with frequent extensive clusters of clonally related B cells connected to mature PB B cells. These clusters showed intensive mutational activity of CSF B cells, providing strong evidence for an independent CNS-based antigen-driven response in patients with LGI1 antibody encephalitis but not in controls.ConclusionsOur results demonstrate that intrathecal immunoglobulin repertoire expansion is a feature of LGI1 antibody encephalitis and suggests a need for CNS-penetrant therapies.

B cells are key contributors to chronic autoimmune pathology in multiple sclerosis (MS). Clonally related B cells exist in the cerebrospinal fluid (CSF), meninges, and CNS parenchyma of MS patients. We sought to investigate the presence of clonally related B cells over time by performing Ig heavy chain variable region repertoire sequencing on B cells from longitudinally collected blood and CSF samples of MS patients (n = 10). All patients were untreated at the time of the initial sampling; the majority (n = 7) were treated with immune-modulating therapies 1.2 (±0.3 SD) years later during the second sampling. We found clonal persistence of B cells in the CSF of 5 patients; these B cells were frequently Ig class-switched and CD27(+). Specific blood B cell subsets appear to provide input into CNS repertoires over time. We demonstrate complex patterns of clonal B cell persistence in CSF and blood, even in patients on immune-modulating therapy. Our findings support the concept that peripheral B cell activation and CNS-compartmentalized immune mechanisms can in part be therapy resistant.

IL-17 has been implicated in the pathogenesis of multiple sclerosis (MS). Here, we show that blockade of IL-17A, but not IL-17F, attenuated experimental autoimmune encephalomyelitis (EAE). We further show that IL-17A levels were elevated in the CSF of relapsing-remitting MS (RRMS) patients and that they correlated with the CSF/serum albumin quotient (Qalb), a measure of blood-brain barrier (BBB) dysfunction. We then demonstrated that the combination of IL-17A and IL-6 reduced the expression of tight junction (TJ)-associated genes and disrupted monolayer integrity in the BBB cell line hCMEC/D3. However, unlike IL-17A, IL-6 in the CSF from RRMS patients did not correlate with Qalb. These data highlight the potential importance of targeting IL-17A in preserving BBB integrity in RRMS.

B-cells are key contributors to chronic autoimmune pathology in multiple sclerosis (MS). Clonally related B-cells exist in the cerebrospinal fluid (CSF), meninges, and central nervous system (CNS) parenchyma of MS patients. Longitudinally stable CSF oligoclonal band (OCB) antibody patterns suggest some local CNS B-cell persistence; however, the longitudinal B-cell dynamics within and between the CSF and blood remain unknown. We sought to address this by performing immunoglobulin heavy chain variable region repertoire sequencing on B-cells from longitudinally collected blood and CSF samples of MS patients (n=10). All patients were untreated at the time of the initial sampling; the majority (n=7) were treated with immune modulating therapies 1.2 (+/−0.3 SD) years later during the second sampling. We found clonal persistence of B-cells in the CSF of five patients; these B-cells were frequently immunoglobulin (Ig) class-switched and CD27+. We identified specific blood B-cell subsets that appear to provide input into CNS repertoires over time. We demonstrate complex patterns of clonal B-cell persistence in CSF and blood, even in patients on high-efficacy immune modulating therapy. Our findings support the concept that peripheral B-cell activation and CNS-compartmentalized immune mechanisms are in part therapy-resistant.

Myelin oligodendrocyte glycoprotein, expressed on the outermost lamellae of the myelin sheath, is a novel and specific binding partner for NGF that may modulate local concentrations of the neurotrophin in the spinal cord microenvironment., Myelin oligodendrocyte glycoprotein (MOG) is a central nervous system myelin-specific molecule expressed on the outer lamellae of myelin. To date, the exact function of MOG has remained unknown, with MOG knockout mice displaying normal myelin ultrastructure and no apparent specific phenotype. In this paper, we identify nerve growth factor (NGF) as a binding partner for MOG and demonstrate that this interaction is capable of sequestering NGF from TrkA-expressing neurons to modulate axon growth and survival. Deletion of MOG results in aberrant sprouting of nociceptive neurons in the spinal cord. Binding of NGF to MOG may offer widespread implications into mechanisms that underlie pain pathways.

A role of B cells in multiple sclerosis (MS) is well established, but there is limited understanding of their involvement during active disease. Here, we examined cerebrospinal fluid (CSF) and peripheral blood (PB) B cells in treatment-naive patients with MS or high-risk clinically isolated syndrome. Using flow cytometry, we found increased CSF lymphocytes with a disproportionate increase of B cells compared with T cells in patients with gadolinium-enhancing (Gd+) lesions on brain MRI. Ig gene heavy chain variable region (Ig-VH) repertoire sequencing of CSF and PB B cells revealed clonal relationships between intrathecal and peripheral B cell populations, which could be consistent with migration of B cells to and activation in the CNS in active MS. In addition, we found evidence for bystander immigration of B cells from the periphery, which could be supported by a CXCL13 gradient between CSF and blood. Understanding what triggers B cells to migrate and home to the CNS may ultimately aid in the rational selection of therapeutic strategies to limit progression in MS.

Large-scale DNA sequencing of immunological repertoires offers an opportunity for the discovery of novel biomarkers for autoimmune disease. Available bioinformatics techniques however, are not adequately suited for elucidating possible biomarker candidates from within large immunosequencing datasets due to unsatisfactory scalability and sensitivity. Here, we present the Haystack Heuristic, an algorithm customized to computationally extract disease-associated motifs from next-generation-sequenced repertoires by contrasting disease and healthy subjects. This technique employs a local-search graph-theory approach to discover novel motifs in patient data. We apply the Haystack Heuristic to nine million B-cell receptor sequences obtained from nearly 100 individuals in order to elucidate a new motif that is significantly associated with multiple sclerosis. Our results demonstrate the effectiveness of the Haystack Heuristic in computing possible biomarker candidates from high throughput sequencing data and could be generalized to other datasets.

We present a precision medicine application developed for multiple sclerosis (MS): the MS BioScreen. This new tool addresses the challenges of dynamic management of a complex chronic disease; the interaction of clinicians and patients with such a tool illustrates the extent to which translational digital medicine-that is, the application of information technology to medicine-has the potential to radically transform medical practice. We introduce 3 key evolutionary phases in displaying data to health care providers, patients, and researchers: visualization (accessing data), contextualization (understanding the data), and actionable interpretation (real-time use of the data to assist decision making). Together, these form the stepping stones that are expected to accelerate standardization of data across platforms, promote evidence-based medicine, support shared decision making, and ultimately lead to improved outcomes.

© 2014 American Neurological Association. Objective: In multiple sclerosis (MS), cerebral gray matter (GM) atrophy correlates more strongly than white matter (WM) atrophy with disability. The corresponding relationships in the spinal cord (SC) are unknown due to technical limitations in assessing SC GM atrophy. Using phase-sensitive inversion recovery (PSIR) magnetic resonance imaging, we determined the association of the SC GM and SC WM areas with MS disability and disease type. Methods: A total of 113 MS patients and 20 healthy controls were examined at 3T with a PSIR sequence acquired at the C2/C3 disk level. Two independent, clinically masked readers measured the cord WM and GM areas. Correlations between cord areas and Expanded Disability Status Score (EDSS) were determined. Differences in areas between groups were assessed with age and sex as covariates. Results: Relapsing MS (RMS) patients showed smaller SC GM areas than age- and sex-matched controls (p = 0.008) without significant differences in SC WM areas. Progressive MS patients showed smaller SC GM and SC WM areas compared to RMS patients (all p ≤ 0.004). SC GM, SC WM, and whole cord areas inversely correlated with EDSS (rho: -0.60, -0.32, -0.42, respectively; all p ≤ 0.001). The SC GM area was the strongest correlate of disability in multivariate models including brain GM and WM volumes, fluid-attenuated inversion recovery lesion load, T1 lesion load, SC WM area, number of SC T2 lesions, age, sex, and disease duration. Brain and spinal GM independently contributed to EDSS. Interpretation: SC GM atrophy is detectable in vivo in the absence of WM atrophy in RMS. It is more pronounced in progressive MS than RMS and contributes more to patient disability than SC WM or brain GM atrophy.

In multiple sclerosis (MS), B cell-depleting therapy using monoclonal anti-CD20 Abs, including rituximab (RTX) and ocrelizumab, effectively reduces disease activity. Based on indirect evidence, it is generally believed that elimination of the Ag-presenting capabilities and Ag nonspecific immune functions of B cells underlie the therapeutic efficacy. However, a small subset of T lymphocytes (T cells) was shown to also express CD20, but controversy prevails surrounding the true existence of this T cell subpopulation. Using single-cell imaging flow cytometry and expression profiling of sorted lymphocyte subsets, we unequivocally demonstrate the existence of CD3+CD20 dim T cells. We show that in MS patients, increased levels of CD3+CD20dim T cells are effectively depleted by RTX. The pathological relevance of this T cell subset in MS remains to be determined. However, given their potential proinflammatory functionality, depletion of CD20-expressing T cells may also contribute to the therapeutic effect of RTX and other mAbs targeting CD20. Copyright © 2014 by The American Association of Immunologists, Inc.

Ectopic lymphoid tissues (ELT) can be found in multiple sclerosis (MS) and other organ-specific inflammatory conditions. Whether ELT in the meninges of central nervous system (CNS) autoimmune disease exhibit local germinal center (GC) activity remains unknown. In an experimental autoimmune encephalomyelitis model of CNS autoimmunity, we found activation-induced cytidine deaminase, a GC-defining enzyme, in meningeal ELT (mELT) densely populated by B and T cells. To determine GC activity in mELT, we excised meningeal lymphoid aggregates using laser capture microscopy and evaluated B cell repertoires in mELT and secondary lymphoid organs by next-generation immune repertoire sequencing. We found immunoglobulin heavy chain variable region sequences that were unique to mELT and had accumulated functionally relevant somatic mutations, together indicating localized antigen-driven affinity maturation. Our results suggest that B cells in mELT actively participate in CNS autoimmunity, which may be relevant to mELT in MS and ELT in other chronic inflammatory conditions.

A patient with relapsing multiple sclerosis (RMS) was treated with a standard immunomodulatory therapy, but due to ongoing disease activity was switched to rituximab. Relapses ceased, but secondary progressive MS (SPMS) eventually appeared, associated with new focal spinal cord white matter lesions. Cerebrospinal fluid (CSF) showed persistent oligoclonal bands (OCB) and clonally related B cells in CSF and peripheral blood. The treatment escalation approach failed to prevent evolution to SPMS, raising the question of whether initiation of B‐cell depleting therapy at the time of RMS diagnosis should be tested to more effectively address the immune pathology leading to SPMS.

Demyelination in MS disrupts nerve signals and contributes to axon degeneration. While remyelination promises to restore lost function, it remains unclear whether remyelination will prevent axonal loss. Inflammatory demyelination is accompanied by significant neuronal loss in the experimental autoimmune encephalomyelitis (EAE) mouse model and evidence for remyelination in this model is complicated by ongoing inflammation, degeneration and possible remyelination. Demonstrating the functional significance of remyelination necessitates selectively altering the timing of remyelination relative to inflammation and degeneration. We demonstrate accelerated remyelination after EAE induction by direct lineage analysis and hypothesize that newly formed myelin remains stable at the height of inflammation due in part to the absence of MOG expression in immature myelin. Oligodendroglial-specific genetic ablation of the M1 muscarinic receptor, a potent negative regulator of oligodendrocyte differentiation and myelination, results in accelerated remyelination, preventing axonal loss and improving functional recovery. Together our findings demonstrate that accelerated remyelination supports axonal integrity and neuronal function after inflammatory demyelination. DOI: http://dx.doi.org/10.7554/eLife.18246.001

© 2015 American Medical Association. All rights reserved. Importance In multiple sclerosis (MS), upper cervical cord gray matter (GM) atrophy correlates more strongly with disability than does brain or cord white matter (WM) atrophy. The corresponding relationships in the thoracic cord are unknown owing to technical difficulties in assessing GMandWMcompartments by conventional magnetic resonance imaging techniques. Objectives To investigate the associations between MS disability and disease type with lower thoracic cord GM andWMareas using phase-sensitive inversion recovery magnetic resonance imaging at 3 T, as well as to compare these relationships with those obtained at upper cervical levels. Design, Setting, and Participants Between July 2013 and March 2014, a total of 142 patients with MS (aged 25-75 years; 86 women) and 20 healthy control individuals were included in this cross-sectional observational study conducted at an academic university hospital. Main Outcomes and Measures Total cord areas (TCAs), GM areas, andWMareas at the disc levels C2/C3, C3/C4, T8/9, and T9/10. Area differences between groups were assessed, with age and sex as covariates. Results Patients with relapsingMS (RMS) had smaller thoracic cord GM areas than did ageand sex-matched control individuals (mean differences [coefficient of variation (COV)]: 0.98 mm2 [9.2%]; P =.003 at T8/T9 and 0.93mm2[8.0%]; P =.01 at T9/T10); however, there were no significant differences in either theWMarea or TCA. Patients with progressiveMS showed smaller GM areas (mean differences [COV]: 1.02mm2[10.6%]; P

Objective To characterize the accrual of long‐term disability in a cohort of actively treated multiple sclerosis (MS) patients and to assess whether clinical and magnetic resonance imaging (MRI) data used in clinical trials have long‐term prognostic value. Methods This is a prospective study of 517 actively managed MS patients enrolled at a single center. Results More than 91% of patients were retained, with data ascertained up to 10 years after the baseline visit. At this last assessment, neurologic disability as measured by the Expanded Disability Status Scale (EDSS) was stable or improved compared to baseline in 41% of patients. Subjects with no evidence of disease activity (NEDA) by clinical and MRI criteria during the first 2 years had long‐term outcomes that were no different from those of the cohort as a whole. 25‐OH vitamin D serum levels were inversely associated with short‐term MS disease activity; however, these levels had no association with long‐term disability. At a median time of 16.8 years after disease onset, 10.7% (95% confidence interval [CI] = 7.2–14%) of patients reached an EDSS ≥ 6, and 18.1% (95% CI = 13.5–22.5%) evolved from relapsing MS to secondary progressive MS (SPMS). Interpretation Rates of worsening and evolution to SPMS were substantially lower when compared to earlier natural history studies. Notably, the NEDA 2‐year endpoint was not a predictor of long‐term stability. Finally, the data call into question the utility of annual MRI assessments as a treat‐to‐target approach for MS care. Ann Neurol 2016;80:499–510

Neuromyelitis optica (NMO) is an inflammatory autoimmune disorder of the CNS that predominantly affects the spinal cord and optic nerves. A majority (approximately 75%) of patients with NMO are seropositive for autoantibodies against the astrocyte water channel aquaporin-4 (AQP4). These autoantibodies are predominantly IgG1, and considerable evidence supports their pathogenicity, presumably by binding to AQP4 on CNS astrocytes, resulting in astrocyte injury and inflammation. Convergent clinical and laboratory-based investigations have indicated that B cells play a fundamental role in NMO immunopathology. Multiple mechanisms have been hypothesized: AQP4 autoantibody production, enhanced proinflammatory B cell and plasmablast activity, aberrant B cell tolerance checkpoints, diminished B cell regulatory function, and loss of B cell anergy. Accordingly, many current off-label therapies for NMO deplete B cells or modulate their activity. Understanding the role and mechanisms whereby B cells contribute to initiation, maintenance, and propagation of disease activity is important to advancing our understanding of NMO pathogenesis and developing effective disease-specific therapies. peerReviewed

Autoantibody responses against conformational epitopes of myelin/oligodendrocyte glycoprotein (MOG) possess myelin destructive potential, as demonstrated in the marmoset model of human multiple sclerosis (MS) and in some rodent models of experimental allergic encephalomyelitis. We have previously characterized monoclonal Fab fragments specific for conformational epitopes of MOG that were derived from a combinatorial antibody library generated from a MOG-immune marmoset. In this paper, we address the molecular heterogeneity of humoral responses against MOG in this outbred model of MS by studying additional antibody clones derived from a genetically unrelated animal. We find that all MOG-specific IgGkappa Fab fragments, unrelated to genetic make-up, utilize a restricted set of variable region genes, IGHV1 and IGHV3 for the H chain and IGKV1, IGKV3, and IGKV5 for the L chain. Despite these restricting factors, diversity within these antibody repertoires can be observed, predominantly within the H-chain CDR3 regions. Our findings suggest that only a limited set of Ig genes is necessary to launch a diverse, destructive humoral immune response against a single CNS antigen in primates. These results are the first to contribute to a better understanding of how myelin-directed and potentially destructive autoantibody responses may develop in human MS.

Background: Collectively, research on the role of B-cells in the pathogenesis of multiple sclerosis (MS) illustrates how translational medicine has given rise to promising therapeutic approaches for one of the most debilitating chronic neurological diseases in young adults. First described in 1935, the experimental autoimmune/allergic encephalomyelitis model is a key animal model that has provided the foundation for important developments in targeted therapeutics. Summary: While additional B-cell therapies for MS are presently being developed by the pharmaceutical industry, much remains to be understood about the role played by B-cells in MS. The goal of this review is to summarize how B-cells may contribute to MS pathogenesis and thereby provide a basis for understanding why B-cell depletion is so effective in the treatment of this disease. Key Messages: B-cells are key players in the pathogenesis of MS, and their depletion via B-cell-targeted therapy ameliorates disease activity. Clinical Implications: In 2008, data from the first CD20-targeting B-cell depleting therapeutic trials using rituximab in MS were published. Since then, there has been a large body of evidence demonstrating the effectiveness of B-cell depletion mediated via anti-CD20 antibodies. Intense research efforts focusing on the immunopathological relevance of B-cells has gained significant momentum and given rise to a constellation of promising therapeutic agents for this complex B-cell-driven disease, including novel anti-CD20 antibodies, as well as agents targeting CD19 and BAFF-R.

In multiple sclerosis (MS), an exchange of lymphocytes, in particular B cells, between the central nervous system (CNS) and periphery is believed to be required for the maintenance of active disease. Therapeutic monoclonal antibodies that prevent lymphocytes from crossing the blood-brain barrier (BBB) or induce near-complete peripheral B cell depletion rapidly mitigate MS disease activity. Using next-generation sequencing technology, we recently found that clonally related B cells exist in the cerebrospinal fluid (CSF) and peripheral blood (PB) of MS patients, establishing the existence of an immune axis across the BBB. However, it remains unclear which subpopulations of the highly diverse peripheral B cell compartment share antigen-specificity with intrathecal B cell repertoires, and whether their antigen stimulation occurs on both sides of the BBB. To address these questions, we combined flow cytometry sorting of PB B cell subsets with deep immune repertoire sequencing of CSF and PB B cells. Immunoglobulin (IgM and IgG) heavy chain variable (VH) region repertoires of five PB B cell subsets from MS patients (n=8) were compared with their CSF Ig-VH transcriptomes. In 6 of 8 patients, we identified peripheral CD27+IgD−memory B cells, CD27hiCD38hi plasma cells/plasmablasts, or CD27−IgD− B cells providing an immune connection to the CNS compartment. Pinpointing Ig class-switched B cells as key component of the immune axis thought to contribute to ongoing MS disease activity strengthens the rationale of current therapeutic strategies and may lead to more targeted approaches.

Objective To determine to what extent oligoclonal band (OCB) specificities are clonally interrelated and to what degree they are associated with corresponding B-cell responses in the peripheral blood (PB) of multiple sclerosis (MS) patients. Methods Mass-spectrometric proteomic analysis of isoelectric focused (IEF) cerebrospinal fluid (CSF) immunoglobulin G (IgG) was used in combination with next-generation deep-immune repertoire sequencing of PB and CSF IgG heavy chain variable regions from MS patients. Results We find evidence for ongoing stimulation and maturation to antibody-expressing B cells to occur primarily inside the central nervous system (CNS) compartment. B cells participating in OCB production can also be identified in PB; these cells appear to migrate across the blood-brain barrier and may also undergo further antigen stimulation in the periphery. In individual patients, different bands comprising OCBs are clonally related. Interpretation Our data provide a high-resolution molecular analysis of OCBs and strongly support the concept that OCBs are not merely the terminal result of a targeted immune response in MS but represent a component of active B cell immunity that is dynamically supported on both sides of the blood-brain barrier. © 2014 American Neurological Association.

In multiple sclerosis (MS) pathogenic B cells likely act on both sides of the blood-brain barrier (BBB). However, it is unclear whether antigen-experienced B cells are shared between the CNS and the peripheral blood (PB) compartments. We applied deep repertoire sequencing of IgG heavy chain variable region genes (IgG-VH) in paired cerebrospinal fluid and PB samples from patients with MS and other neurological diseases to identify related B cells that are common to both compartments. For the first time to our knowledge, we found that a restricted pool of clonally related B cells participated in robust bidirectional exchange across the BBB. Some clusters of related IgG-VH appeared to have undergone active diversification primarily in the CNS, while others have undergone active diversification in the periphery or in both compartments in parallel. B cells are strong candidates for autoimmune effector cells in MS, and these findings suggest that CNS-directed autoimmunity may be triggered and supported on both sides of the BBB. These data also provide a powerful approach to identify and monitor B cells in the PB that correspond to clonally amplified populations in the CNS in MS and other inflammatory states.

A diverse antibody repertoire is essential for an effective adaptive immune response to novel molecular surfaces. Although past studies have observed common patterns of V-segment use, as well as variation in V-segment use between individuals, the relative contributions to variance from genetics, disease, age, and environment have remained unclear. Using high-throughput sequence analysis of monozygotic twins, we show that variation in naive V H and D H segment use is strongly determined by an individual's germ-line genetic background. The inherited segment-use profiles are resilient to differential environmental exposure, disease processes, and chronic lymphocyte depletion therapy. Signatures of the inherited profiles were observed in class switched germ-line use of each individual. However, despite heritable segment use, the rearranged complementarity-determining region-H3 repertoires remained highly specific to the individual. As it has been previously demonstrated that certain V-segments exhibit biased representation in autoimmunity, lymphoma, and viral infection, we anticipate our findings may provide a unique mechanism for stratifying individual risk profiles in specific diseases.

Background Myelin/oligodendrocyte glycoprotein (MOG) is a putative autoantigen in multiple sclerosis (MS). Establishing the pathological relevance and validity of anti-MOG antibodies as biomarkers has yielded conflicting reports mainly due to different MOG isoforms used in different studies. Because epitope specificity may be a key factor determining anti-MOG reactivity we aimed at identifying a priori immunodominant MOG epitopes by monoclonal antibodies (mAbs) and at assessing clinical relevance of these epitopes in MS. Methods Sera of 325 MS patients, 69 patients with clinically isolated syndrome and 164 healthy controls were assayed by quantitative, high-throughput ELISA for reactivity to 3 different MOG isoforms, and quantitative titers correlated with clinical characteristics. mAbs defined unique immunodominant epitopes distinct to each of the isoforms. Results In the majority of human samples anti-MOG levels were skewed towards low titers. However, in 8.2% of samples high-titer anti-MOG antibodies were identified. In contrast to anti-MOG reactivity observed in a mouse model of MS, in patients with MS these never reacted with ubiquitously exposed epitopes. Moreover, in patients with relapsing-remitting MS high-titer anti-MOG IgG correlated with disability (EDSS; Spearman r = 0.574; p = 0.025). Conclusions Thus high-titer reactivity likely represents high-affinity antibodies against pathologically relevant MOG epitopes, that are only present in a small proportion of patients with MS. Our study provides valuable information about requirements of anti-MOG reactivity for being regarded as a prognostic biomarker in a subtype of MS.

Over the past two decades B cells have increasingly moved into the spotlight in multiple sclerosis (MS) research. This interest was fuelled by growing understanding and acceptance of pathological involvement of B cells and antibodies in MS. Data derived from animal models of MS, human histopathological studies, and analyses of B cells in the peripheral blood and cerebrospinal fluid (CSF) have permitted the integration of B cells in our overall picture of MS immunopathogenesis. The as yet strongest direct evidence for a central role of B cells in MS autoimmunity was the demonstration that peripheral B cell depletion leads to a rapid decline of disease-activity in MS. While lending formidable impact to peripheral blood B cells as mediators of disease activity, the effects of anti-CD20 treatment also seemingly challenged the paradigm of a role of antibodies in targeted central nervous system (CNS) myelin destruction. This review shall attempt to provide an overview of our current understanding of B cell and antibody mediated mechanisms relevant to MS. We will include findings from, both, human studies, and animal models to highlight the complexity of B cell function as it pertains to MS. B cells appear to be effective drivers of inflammatory activity in MS by way of a diverse toolset of cellular functions. These functions appear to be closely linked to B cells that can be found in the periphery. However, by serving as the source of antibodies, B cells offer a direct humoral response that may target the CNS and lead to tissue specific destruction. Therefore, B cells participate in MS pathogenesis on both sides of the blood-brain barrier.

Background Leucine-rich glioma inactivated 1 (LGI1) is a component of the voltage-gated potassium channel complex. IgG antibodies against LGI1 are associated with immunotherapy-responsive encephalitis and epilepsies. LGI1-antibody concentrations are 10–100 times greater in serum than in cerebrospinal fluid (CSF). Oligoclonal IgG bands are rarely found in patients with LGI1-antibody encephalitis or epilepsy. These observations raise questions about the sources of the B cells that result in production of LGI1 antibodies and how the IgGs reach the brain. We aimed to investigate the migration and expansions of peripheral and central B cells to the production of LGI1-specific IgG. Methods We performed PCR amplification and next generation deep immune repertoire sequencing of immunoglobulin (Ig) heavy chain variable regions (VH) from CSF and subsorted peripheral blood B-cell populations from two patients with limbic encephalitis and faciobrachial dystonic seizures associated with LGI1 antibodies. Bioinformatics clustering of related IgM-VH or IgG-VH transcripts was used to determine whether active B-cell diversification could be observed, and whether intrathecal B-cell repertoires, if present, were related to peripheral B cells. Findings We identified clusters of related Ig-VH transcripts in the CSF of both patients. Within these clusters there was a range of somatic hypermutations along the IGHV germline segment-derived portion. In addition, we identified a large number of closely related Ig-VH clusters that were common to both CSF and peripheral blood, including a small number of dominating Ig-VH clusters that might represent the most active clonally related B-cell populations. Interpretation Our data suggest that some B-cell affinity maturation occurs inside the CNS compartment in LGI1-antibody encephalitis. Somatic hypermutation rates point to a CSF antigen-driven activation of clonally related B cells that shape the intrathecal immune repertoire. The target antigen or antigens of these clonally related B cells remain unknown; our work continues to determine the relative contribution of intrathecally activated and peripheral LGI1-specific B cells in this autoimmune CNS disease. Funding Wellcome Trust Intermediate Fellowship to SRI, Fulbright-MS Society, Epilepsy Research UK, BMA Vera Down Research Grant.

Background: Leucine-rich glioma inactivated 1 (LGI1) is a component of the voltage-gated potassium channel complex (VGKC). Antibodies against LGI1 are associated with limbic encephalitis and related central nervous system (CNS) disorders. In most patients, anti-LGI1 antibodies are found in the serum, while their occurrence in the cerebrospinal fluid (CSF) is much less common. Oligoclonal IgG (oligoclonal bands, OCB), a prominent indicator for intrathecal B cell activation, are rarely found in patients with LGI1 encephalitis. Overall, the immune pathology resulting in LGI1 autoimmunity is unclear. However, partially due to the absence of OCB, peripheral immune processes are believed to be the principal disease drivers. Objective: To investigate whether an active intrathecal B cell immune response is present in patients with LGI1 antibodies. Methods: We applied PCR amplification and next generation deep immune repertoire sequencing (DIRS) of B cell receptor immunoglobulin (Ig) heavy chain variable regions (VH) from CSF and peripheral blood B cells of 2 patients with LGI1 encephalitis. Extensive bioinformatics clustering of related IgM-VH or IgG-VH transcripts was employed to determine 1) whether active B cell immune mechanisms operate in LGI1 encephalitis, and 2) whether intrathecal B cell repertoires, if present, are related to peripheral B cells. Results: We identified numerous clusters of related Ig-VH transcripts in the CSF of both patients; within these clusters we found a range of somatic hypermutations (SHM) along the IGHV germline segmentderived portion suggesting that local antigen-driven activation of clonally related B cells was involved in shaping the intrathecal immune repertoire. Furthermore, we identified a large number of closely related Ig-VH clusters that were common to both, CSF and periphery. Interestingly, in each patient we identified a small number of dominating Ig-VH clusters that may represent the most active clonally related B cell populations. Conclusion: Our data suggest that in LGI1 encephalitis B cell affinity maturation occurs inside the CNS compartment. The target antigen(s) of the clonally related B cells described here remain unknown; ongoing work will determine whether intrathecally activated B cells and/or B cells that apparently target identical antigens in the periphery and CNS compartments are involved in LGI1 autoimmunity.