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Background: Myelin oligodendrocyte glycoprotein antibody-associated autoimmune disease (MOGAD) is a rare monophasic or relapsing inflammatory demyelinating disease of the central nervous system (CNS) and can mimic multiple sclerosis (MS). The variable availability of live cell-based MOG-antibody assays and difficulties in interpreting low-positive antibody titers can complicate diagnosis. Literature on cerebrospinal fluid (CSF) profiles in MOGAD versus MS, one of the most common differential diagnoses, is scarce. We here analyzed the value of basic CSF parameters to i) distinguish different clinical MOGAD manifestations and ii) differentiate MOGAD from MS., Methods: This is retrospective, single-center analysis of clinical and laboratory data of 30 adult MOGAD patients and 189 adult patients with relapsing-remitting multiple sclerosis. Basic CSF parameters included CSF white cell count (WCC) and differentiation, CSF/serum albumin ratio (Q Alb ), intrathecal production of immunoglobulins, CSF-restricted oligoclonal bands (OCB) and MRZ reaction, defined as intrathecal production of IgG reactive against at least 2 of the 3 viruses measles (M), rubella (R) and varicella zoster virus (Z)., Results: MOGAD patients with myelitis were more likely to have a pleocytosis, a Q Alb elevation and a higher WCC than those with optic neuritis, and, after review and combined analysis of our and published cases, they also showed a higher frequency of intrathecal IgM synthesis. Compared to MS, MOGAD patients had significantly more frequently neutrophils in CSF and WCC>30/µl, Q Alb >10×10 -3 , as well as higher mean Q Alb values, but significantly less frequently CSF plasma cells and CSF-restricted OCB. A positive MRZ reaction was present in 35.4% of MS patients but absent in all MOGAD patients. Despite these associations, the only CSF parameters with relevant positive likelihood ratios (PLR) indicating MOGAD were Q Alb >10×10 -3 (PLR 12.60) and absence of CSF-restricted OCB (PLR 14.32), whereas the only relevant negative likelihood ratio (NLR) was absence of positive MRZ reaction (NLR 0.00)., Conclusion: Basic CSF parameters vary considerably in different clinical phenotypes of MOGAD, but Q Alb >10×10 -3 and absence of CSF-restricted OCB are highly useful to differentiate MOGAD from MS. A positive MRZ reaction is confirmed as the strongest CSF rule-out parameter in MOGAD and could be useful to complement the recently proposed diagnostic criteria., Competing Interests: MR was supported by a research support from Euroimmun and Roche. The University Hospital and Medical University of Innsbruck Austria, employer of Dr. Reindl receives payments for antibody assays MOG, AQP4, and other autoantibodies and for MOG and AQP4 antibody validation experiments organized by Euroimmun Lübeck, Germany. AL received financial compensation and/or travel support for lectures and advice from Biogen, Merck, Novartis, Teva, Genzyme, Roche, Bayer, Celgene and he is a co-founder and co-owner of Cellerys, a company which pursues antigen-specific tolerization. He is co-inventor on a patent held by the University of Zurich on the use of peptide-coupled cells for treatment of MS. IJ has received speaker honoraria or unrestricted grants from Biogen Idec and Novartis and has received compensation for advice or lecturing by for Alexion, Biogen, Bristol Myers Squibb, Celgene, Janssen-Cilag, Neuway, Merck, Novartis, Roche and Sanofi Genzyme; none of these are related to this study. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be constructed as a potential conflict of interest., (Copyright © 2023 Vlad, Reichen, Neidhart, Hilty, Lekaditi, Heuer, Eisele, Ziegler, Reindl, Lutterotti, Regeniter and Jelcic.)

Background: Anti-neuronal autoantibodies have been reported as the cause of several neurologic disorders other than encephalitis. Unfortunately, data are mostly based on serum analysis. Predictions about pathogenicity are thus limited. To determine the presence of so far unidentified autoantibody-derived neuroreactivity we analyzed cerebrospinal fluid (CSF) of children with neurological disorders other than encephalitis., Patients and Methods: We did a retrospective analysis of CSF from 254 children with various neurologic diseases other than encephalitis and searched for reactivity against neuronal surface antigens by immunofluorescence on unfixed murine brain sections (tissue-based assay, TBA) and by commercial cell-based assays (CBA). A semi-quantitative fluorescence score classified our results and we described the clinical course of all positive patients with strong neuroreactivity., Results: Strong anti-neuronal IgG immunoreactivity of unknown antigen specificity was detected in CSF samples of 10 pediatric patients (4%, n = 10/254) with unsolved neurological disorders. CSF inflammatory markers were elevated. Most patients did not or only partly recover. Five screening-positive patients presented with a combination of headache and visual impairment due to optic nerve atrophy. Our data suggest to consider inflammatory, autoantibody-related etiologies, especially in cases without definite diagnoses., Conclusions: We present an overview of CSF neuroreactivity in children with neurological disorders other than encephalitis, indicating the presence of unidentified anti-neuronal autoantibodies. As TBA enables screening for unknown autoantibodies, we suggest this method as a second step if commercial CBAs do not yield a result. Further studies are necessary to characterize such antibodies, evaluate pathogenicity, and answer the question whether positive CSF neuroreactivity should prompt an immunotherapeutic approach., Competing Interests: Declaration of competing interest The authors have no conflicts of interest relevant to this article to disclose., (Copyright © 2020 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

Multiple sclerosis (MS) is caused by T cells that are reactive for brain antigens. In experimental autoimmune encephalomyelitis, the animal model for MS, myelin-reactive T cells initiate the autoimmune process when entering the nervous tissue and become reactivated upon local encounter of their cognate CNS antigen. Thereby, the strength of the T-cellular reactivation process within the CNS tissue is crucial for the manifestation and the severity of the clinical disease. Recently, B cells were found to participate in the pathogenesis of CNS autoimmunity, with several diverse underlying mechanisms being under discussion. We here report that B cells play an important role in promoting the initiation process of CNS autoimmunity. Myelin-specific antibodies produced by autoreactive B cells after activation in the periphery diffused into the CNS together with the first invading pathogenic T cells. The antibodies accumulated in resident antigen-presenting phagocytes and significantly enhanced the activation of the incoming effector T cells. The ensuing strong blood-brain barrier disruption and immune cell recruitment resulted in rapid manifestation of clinical disease. Therefore, myelin oligodendrocyte glycoprotein (MOG)-specific autoantibodies can initiate disease bouts by cooperating with the autoreactive T cells in helping them to recognize their autoantigen and become efficiently reactivated within the immune-deprived nervous tissue.

To ascertain the consequences of severe leukopenia and the tempo of recovery, we studied the immunity of 56 adult patients treated for multiple sclerosis or systemic sclerosis with autologous CD34 cell transplantation using extremely lymphoablative conditioning. NK cell, monocyte, and neutrophil counts recovered to normal by 1 month; dendritic cell and B cell counts by 6 months; and T cell counts by 2 years posttransplant, although CD4 T cell counts remained borderline low. Initial peripheral expansion was robust for CD8 T cells but only moderate for CD4 T cells. Subsequent thymopoiesis was slow, especially in older patients. Importantly, levels of antibodies, including autoantibodies, did not drop substantially. Infections were frequent during the first 6 months, when all immune cells were deficient, and surprisingly rare (0.21 per patient year) at 7-24 months posttransplant, when only T cells (particularly CD4 T cells) were deficient. In conclusion, peripheral expansion of CD8 but not CD4 T cells is highly efficient. Prolonged CD4 lymphopenia is associated with relatively few infections, possibly due to antibodies produced by persisting pretransplant plasma cells.

Background: The presence of circulating anti-myelin oligodendrocyte glycoprotein antibodies (MOG-Abs) has been described in sera of patients with different inflammatory conditions of the central nervous system. In adults the core clinical feature is usually characterised by acute myelitis and/or optic neuritis. We here report an atypical case with serum and cerebrospinal fluid MOG-Abs and a clinical picture suggestive for acute encephalitis.Case Presentation: A 31-year-old Indian man presented with altered mental status, slight fever, and ataxia. Brain magnetic resonance imaging noted a widespread involvement of the white matter associated with slight cortical and subcortical damage in absence of contrast enhancement. An extensive infectious screening resulted negative while autoimmune analysis revealed the presence of MOG-Abs, detected with live cell-based assay. After treatment with intravenous immunoglobulins a marked and prompt clinical and radiological improvement was observed.Conclusions: To date, several areas of uncertainty still remain regarding clinical features and prognosis of subjects with MOG-Abs. The description of atypical cases is crucial, since recognition of this condition leads to prompt treatment and better prognosis, as in the case here reported. [ABSTRACT FROM AUTHOR]

Background: There is evidence that B cells play an important role in disease pathology of multiple sclerosis (MS). The aim of this prospective observational study was to determine the predictive value of cerebrospinal fluid (CSF) B cell subtypes in disease evolution of patients with MS. Materials and methods: 128 patients were included between 2004 and 2012. Median follow up time was 7.9 years (range 3.3–10.8 years). 10 patients were lost to follow-up. 32 clinically isolated syndrome- (CIS), 25 relapsing remitting MS- (RRMS), 2 secondary progressive MS- (SPMS) and 9 primary progressive MS- (PPMS) patients were included. The control group consisted of 40 patients with other neurological diseases (OND). CSF samples were analyzed for routine diagnostic parameters. B cell phenotypes were characterized by flow cytometry using CD19 and CD138 specific antibodies. Standardized baseline brain MRI was conducted at the time of diagnostic lumbar puncture. Main outcome variables were likelihood of progressive disease course, EDSS progression, conversion to clinical definite MS (CDMS) and relapse rate. Results: CSF mature B cells (CD19+CD138-) were increased in bout-onset MS compared to PPMS (p<0.05) and OND (p<0.001), whereas plasma blasts (CD19+CD138+) were increased in bout-onset MS (p<0.001) and PPMS (p<0.05) compared to OND. CSF B cells did not predict a progressive disease course, EDSS progression, an increased relapse rate or the conversion to CDMS. Likelihood of progressive disease course (p<0.05) and EDSS (p<0.01) was predicted by higher age at baseline, whereas conversion to CDMS was predicted by a lower age at onset (p<0.01) and the presence of ≥9 MRI T2 lesions (p<0.05). Conclusion: We detected significant differences in the CSF B cell subsets between different clinical MS subtypes and OND patients. CSF B cells were neither predictive for disease and EDSS progression nor conversion to CDMS after a CIS. [ABSTRACT FROM AUTHOR]

Background: Paroxysmal (PS) and unusual symptoms (US) account for approximately 1.6% of initial manifestations of multiple sclerosis (MS) and have comparable conversion rates to clinically definite MS (CDMS) as classical bout onset symptoms (CS). However, long-term prognosis and clinical outcome of patients experiencing PS or US as first clinical manifestation are unclear. Methods: Clinical, MRI and cerebrospinal fluid data were obtained retrospectively and patients presenting with PS or US were compared to patients with CS presentation. Results: In a cohort of 532 relapsing onset MS patients followed for a mean period of 11.4 years (SD 3.6), 10 (1.9%) patients initially presented with PS/US. PS/US patients received disease modifying treatment (DMT) in a significantly smaller proportion immediately after the first clinical symptom (30% vs. 61.7%; p = 0.021) and during the observation period (60% vs. 83.5%; p = 0.033). In multivariate models correcting for sex, age at initial symptoms, complete remission of initial symptoms, total number of T2 and contrast-enhancing lesions, presence of oligoclonal bands and DMT exposure, PS/US were not associated with lower annualized relapse rate or lower EDSS over time. Conclusion: In addition to a similar conversion rate to CDMS, patients presenting with PS/US at disease onset display very similar relapse and disability rates as patients with CS onset. Consequently, initial presentation with PS/US does not indicate benign or atypical MS, but requires DMT initiation based on the same criteria as in CS patients. [ABSTRACT FROM AUTHOR]

Background: Multiple sclerosis (MS) has a highly heterogenic course making prediction of long term outcome very difficult. Objective: The objective was to evaluate current and identify additional clinical factors that are linked to long term outcome of relapsing-remitting MS assessed by disability status 10 years after disease onset. Methods: This observational study included 793 patients with relapsing-remitting MS. Clinical factors hypothesized to influence long term outcome measured by EDSS scores 10 years after disease onset were analysed by Kaplan-Meier-estimates. Multinomial logistic regression models regarding mild (EDSS ≤2.5), moderate (EDSS 3.0–5.5) or severe (EDSS ≥6.0) disability were calculated to correct for confounders. Results: Secondary progression was the strongest predictor of severe disability (Hazard ratio [HR] 503.8, 95% confidence interval [CI] 160.0–1580.1); p<0.001). Complete remission of neurological symptoms at onset reduced the risk of moderate disability (HR 0.42; CI 0.23–0.77; p = 0.005), while depression (HR 3.59; CI 1.14–11.24; p = 0.028) and cognitive dysfunction (HR 4.64; CI 1.11–19.50; p = 0.036) 10 years after disease onset were associated with severe disability. Oligoclonal bands and pregnancy were not correlated with disability. Conclusion: We were able to identify clinically apparent chronic depression and cognitive dysfunction to be associated with adverse long term outcome in MS and to confirm that pregnancy has no negative impact. Additionally, we emphasize the positive predictive value of complete remission of initial symptoms. [ABSTRACT FROM AUTHOR]

In the pathogenesis of central nervous system (CNS) demyelinating disorders, antigen-specific B cells are implicated to act as potent antigen-presenting cells (APC), eliciting waves of inflammatory CNS infiltration. Here, we provide the first evidence that CNS-reactive antibodies (Ab) are similarly capable of initiating an encephalitogenic immune response by targeting endogenous CNS antigen to otherwise inert myeloid APC. In a transgenic mouse model, constitutive production of Ab against myelin oligodendrocyte glycoprotein (MOG) was sufficient to promote spontaneous experimental autoimmune encephalomyelitis (EAE) in the absence of B cells, when mice endogenously contained MOG-recognizing T cells. Adoptive transfer studies corroborated that anti-MOG Ab triggered activation and expansion of peripheral MOG-specific T cells in an Fc-dependent manner, subsequently causing EAE. To evaluate the underlying mechanism, anti-MOG Ab were added to a co-culture of myeloid APC and MOG-specific T cells. At otherwise undetected concentrations, anti-MOG Ab enabled Fc-mediated APC recognition of intact MOG; internalized, processed and presented MOG activated naïve T cells to differentiate in an encephalitogenic manner. In a series of translational experiments, anti-MOG Ab from two patients with an acute flare of CNS inflammation likewise facilitated detection of human MOG. Jointly, these observations highlight Ab-mediated opsonization of endogenous CNS auto-antigen as a novel disease- and/or relapse-triggering mechanism in CNS demyelinating disorders. [ABSTRACT FROM AUTHOR]

Background: The discovery of a highly specific antibody against the aquaporin-4 (AQP4) water channel (AQP4-IgG) unified the spectrum of neuromyelitis optica spectrum disorders (NMOSD), which are considered to be antibody-mediated autoimmune diseases. The AQP4 water channel is located on astrocytic end-feet processes and consists of six transmembrane helical domains forming three extracellular loops A, C, and E in which defined amino acids were already proven to be critical for AQP4-IgG binding. However, the clinical relevance of these findings is unclear. Therefore, we have characterized the epitope specificity of AQP4-IgG-positive NMOSD patients.Methods: We established a cell-based flow cytometry assay for the quantitative detection of AQP4-IgG-positive serum samples. Human embryonic kidney (HEK) cells were transiently transfected with an EmGFP-tagged AQP4-M23, AQP4-M1, or six AQP4-M23 extracellular loop mutants including two mutations in loop A (serial AA substitution, insertion of a myc-tag), two in loop C (N153Q, insertion of a myc-tag), and two in loop E (H230G, insertion of a myc-tag). Fourty-seven baseline and 49 follow-up serum samples and six paired cerebrospinal fluid (CSF) baseline samples of 47 AQP4-IgG-positive Austrian NMOSD patients were then tested for their binding capability to AQP4-M1 and AQP4-M23 isoforms and these six extracellular loop mutants.Results: Overall, we could identify two broad patterns of antibody recognition based on differential sensitivity to mutations in extracellular loop A. Pattern A was characterized by reduced binding to the two mutations in loop A, whereas pattern B had only partial or no reduced binding to these mutations. These two patterns were not associated with significant differences in demographic and clinical parameters or serum titers in this retrospective study. Interestingly, we found a change of AQP4-IgG epitope recognition pattern in seven of 20 NMOSD patients with available follow-up samples. Moreover, we found different binding patterns in five of six paired CSF versus serum samples, with a predominance of pattern A in CSF.Conclusions: Our study demonstrates that AQP4-IgG in sera of NMOSD patients show distinct patterns of antibody recognition. The clinical and diagnostic relevance of these findings have to be addressed in prospective studies. [ABSTRACT FROM AUTHOR]

Myelin-associated inhibition of axonal regrowth after injury is considered one important factor that contributes to regeneration failure in the adult central nervous system (CNS). Blocking strategies targeting this pathway have been successfully applied in several nerve injury models, including experimental autoimmune encephalomyelitis (EAE), suggesting myelin-associated inhibitors (MAIs) and functionally related molecules as targets to enhance regeneration in multiple sclerosis. NgR1 and NgR2 were identified as interaction partners for the myelin proteins Nogo-A, MAG and OMgp and are probably mediating their growth-inhibitory effects on axons, although the in vivo relevance of this pathway is currently under debate. Recently, alternative functions of MAIs and NgRs in the regulation of immune cell migration and T cell differentiation have been described. Whether and to what extent NgR1 and NgR2 are contributing to Nogo and MAGrelated inhibition of neuroregeneration or immunomodulation during EAE is currently unknown. Here we show that genetic deletion of both receptors does not promote functional recovery during EAE and that NgR1 and NgR2-mediated signals play a minor role in the development of CNS inflammation. Induction of EAE in Ngr1/2-double mutant mice resulted in indifferent disease course and tissue damage when compared to WT controls. Further, the development of encephalitogenic CD4+ Th1 and Th17 responses was unchanged. However, we observed a slightly increased leukocyte infiltration into the CNS in the absence of NgR1 and NgR2, indicating that NgRs might be involved in the regulation of immune cell migration in the CNS. Our study demonstrates the urgent need for a more detailed knowledge on the multifunctional roles of ligands and receptors involved in CNS regeneration failure. [ABSTRACT FROM AUTHOR]

αB-crystallin (αBC), a small stress protein with cytoprotective and anti-apoptotic functions, is a potent antigen in autoimmune demyelinating diseases. To address the role of αBC in Guillain-Barré syndrome (GBS) we analyzed humoral responses against αBC in relation to clinical, electrophysiological and CSF features in GBS. Anti-αBC-IgG antibodies were measured in serum and cerebrospinal fluid (CSF) of patients with GBS (n = 41), infectious inflammatory neurological diseases (n = 21), multiple sclerosis (n = 42), and other, non-inflammatory neurological disorders (n = 40) by ELISA using human recombinant αBC. Expression of αBC was immunohistochemically analyzed in postmortem peripheral nerve tissue of GBS and controls without neuropathy. Serum αBC-IgG antibody levels did not differ between disease groups, whereas αBC-IgG antibodies in CSF were increased in GBS and infectious inflammatory neurological diseases. Calculation of an antigen specific αBC-IgG index (αBC-Ig-GCSF × total IgGCSF)/(αBC-IgGSerum × total IgGSerum) revealed significantly elevated values in patients with GBS compared to other disease groups (p < 0.001). αBC-IgG indices exceeding a cut off value > 0.8 had an 85 % specificity and a 76 % sensitivity for GBS. αBC was overexpressed in dorsal root ganglia and spinal roots of autopsy cases with GBS. We demonstrate increased αBC-IgG indices in a high proportion of our GBS patients, which reflect enhanced antigen-specific intrathecal antibody responses against abnormally expressed αBC in inflamed peripheral nerve tissue. Elevated αBC-IgG indices might therefore serve as markers of PNS inflammation and supplement currently used laboratory tests in the diagnosis of GBS. [ABSTRACT FROM AUTHOR]

Encephalitis is a severe inflammatory disorder of the brain with many possible causes and a complex differential diagnosis. Advances in autoimmune encephalitis research in the past 10 years have led to the identification of new syndromes and biomarkers that have transformed the diagnostic approach to these disorders. However, existing criteria for autoimmune encephalitis are too reliant on antibody testing and response to immunotherapy, which might delay the diagnosis. We reviewed the literature and gathered the experience of a team of experts with the aims of developing a practical, syndrome-based diagnostic approach to autoimmune encephalitis and providing guidelines to navigate through the differential diagnosis. Because autoantibody test results and response to therapy are not available at disease onset, we based the initial diagnostic approach on neurological assessment and conventional tests that are accessible to most clinicians. Through logical differential diagnosis, levels of evidence for autoimmune encephalitis (possible, probable, or definite) are achieved, which can lead to prompt immunotherapy. [ABSTRACT FROM AUTHOR]