Myelin oligodendrocyte glycoprotein antibodies in neurological disease

The extracellular region of bovine milk butyrophilin exhibits closer structural similarity to human myelin oligodendrocyte glycoprotein than to immunological BTN family receptors

Bovine butyrophilin (BTN1A1) is an abundant type I transmembrane glycoprotein exposed on the surface of milk fat globules. We have solved the crystal structure of its extracellular region via multiple wavelength anomalous dispersion after incorporation of selenomethionine into the bacterially produced protein. The butyrophilin ectodomain exhibits two subdomains with immunoglobulin fold, each comprising a β-sandwich with a central disulfide bridge as well as one N-linked glycosylation. The fifth Cys residue at position 193 is unpaired and prone to forming disulfide crosslinks. The apparent lack of a ligand-binding site or receptor activity suggests a function predominantly as hydrophilic coat protein to prevent coagulation of the milk fat droplets. While there is less structural resemblance to members of the human butyrophilin family such as BTN3A, which play a role as immune receptors, the N-terminal bovine butyrophilin subdomain shows surprising similarity to the human myelin oligodendrocyte glycoprotein, a protein exposed on the surface of myelin sheaths. Thus, our study lends structural support to earlier hypotheses of a correlation between the consumption of cow milk and prevalence of neurological autoimmune diseases and may offer guidance for the breeding of cattle strains that express modified butyrophilin showing less immunological cross-reactivity.

T-Cell Specificity Influences Disease Heterogeneity in Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Encouraged by the enormous progress that the identification of specific autoantigens added to the understanding of neurologic autoimmune diseases, we undertook here an in-depth study of T-cell specificities in the autoimmune disease multiple sclerosis (MS), for which the spectrum of responsible autoantigens is not fully defined yet. The identification of target antigens in MS is crucial for therapeutic strategies aimed to induce antigen-specific tolerance. In addition, knowledge of relevant T-cell targets can improve our understanding of disease heterogeneity, a hallmark of MS that complicates clinical management.

METHODS

The proliferative response and interferon gamma (IFN-γ) release of CSF-infiltrating CD4⁺ T cells from patients with MS against several autoantigens was used to identify patients with different intrathecal T-cell specificities. Fresh CSF-infiltrating and paired circulating lymphocytes in these patients were characterized in depth by ex vivo immunophenotyping and transcriptome analysis of relevant T-cell subsets. Further examination of these patients included CSF markers of inflammation and neurodegeneration and a detailed characterization with respect to demographic, clinical, and MRI features.

RESULTS

By testing CSF-infiltrating CD4⁺ T cells from 105 patients with MS against seven long-known myelin and five recently described GDP-l-fucose synthase peptides, we identified GDP-l-fucose synthase and myelin oligodendrocyte glycoprotein (35-55) responder patients. Immunophenotyping of CSF and paired blood samples in these patients revealed a significant expansion of an effector memory (CCR7^- CD45RA^-) CD27^- Th1 CD4⁺ cell subset in GDP-l-fucose synthase responders. Subsequent transcriptome analysis of this subset demonstrated expression of Th1 and cytotoxicity-associated genes. Patients with different intrathecal T-cell specificities also differ regarding inflammation- and neurodegeneration-associated biomarkers, imaging findings, expression of HLA class II alleles, and seasonal distribution of the time of the lumbar puncture.

DISCUSSION

Our observations reveal an association between autoantigen reactivity and features of disease heterogeneity that strongly supports an important role of T-cell specificity in MS pathogenesis. These data have the potential to improve patient classification in clinical practice and to guide the development of antigen-specific tolerization strategies.

Neuromyelitis optica spectrum disorders: from pathophysiology to therapeutic strategies

Neuromyelitis optica (NMO) is a chronic inflammatory autoimmune disease of the central nervous system (CNS) characterized by acute optic neuritis (ON) and transverse myelitis (TM). NMO is caused by a pathogenic serum IgG antibody against the water channel aquoporin 4 (AQP4) in the majority of patients. AQP4-antibody (AQP4-ab) presence is highly specific, and differentiates NMO from multiple sclerosis. It binds to AQP4 channels on astrocytes, triggering activation of the classical complement cascade, causing granulocyte, eosinophil, and lymphocyte infiltration, culminating in injury first to astrocyte, then oligodendrocytes followed by demyelination and neuronal loss. NMO spectrum disorder (NMOSD) has recently been defined and stratified based on AQP4-ab serology status. Most NMOSD patients experience severe relapses leading to permanent neurologic disability, making suppression of relapse frequency and severity, the primary objective in disease management. The most common treatments used for relapses are steroids and plasma exchange.Currently, long-term NMOSD relapse prevention includes off-label use of immunosuppressants, particularly rituximab. In the last 2 years however, three pivotal clinical trials have expanded the spectrum of drugs available for NMOSD patients. Phase III studies have shown significant relapse reduction compared to placebo in AQP4-ab-positive patients treated with satralizumab, an interleukin-6 receptor (IL-6R) inhibitor, inebilizumab, an antibody against CD19⁺ B cells; and eculizumab, an antibody blocking the C5 component of complement. In light of the new evidence on NMOSD pathophysiology and of preliminary results from ongoing trials with new drugs, we present this descriptive review, highlighting promising treatment modalities as well as auspicious preclinical and clinical studies.

Prolonged Fever: An Atypical Presentation in MOG Antibody-Associated Disorders

BACKGROUND

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated demyelinating disorders (MOGAD) are increasingly being recognized in the pediatric age group. Over time, unusual presentations have expanded the clinical presentation. We report 12 cases of MOGAD where prolonged fever (PF) was an important part of the symptom complex during the course of the illness.

METHODS

After initial recognition of this atypical clinical presentation, more patients were recruited over 2 years and followed up prospectively.

RESULTS

Eight of twelve patients had no clinical/imaging evidence of demyelination until much later in the course. Three clinical presentations recognized were fever of unknown origin (4 of 12), aseptic meningitis (4 of 12), and PF seen concurrently with established acute demyelination syndrome (4 of 12). Leukocytosis, raised inflammatory markers, and cerebrospinal fluid pleocytosis were almost universal. The first two presentations frequently caused diagnostic confusion, as MOGAD was not considered until several weeks after disease onset. The third group was more a therapeutic conundrum on how to manage the PF. Early seizures without encephalopathy were not uncommon and were probably independent of the later-appearing demyelination.

CONCLUSIONS

This case series highlights PF as an important component of the pediatric MOGAD symptom complex. MOGAD could be considered in the differential diagnosis of these clinical presentations.

Facial Nerve Involvement Accompanying Optic Neuritis Secondary to Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disorder

ABSTRACT

We present the first reported case of facial nerve involvement accompanying an optic neuritis in myelin oligodendrocyte glycoprotein antibody-associated disorder.

Transient Myelin Oligodendrocyte Glycoprotein Antibody-positive Acute Disseminated Encephalomyelitis Following Influenza A Infection: A Rare Case

Acute disseminated encephalomyelitis (ADEM) is an uncommon disease generally with a preceding history of infectious illness. Here, we report a rare case of ADEM following influenza A infection with transient detection of anti-myelin oligodendrocyte glycoprotein (MOG) antibody in a young male patient who presented with extensive demyelination of brain and spinal cord, likely the result of dysregulated immune response from previous influenza A infection. The patient presented to the emergency with urinary retention and progressive ascending weakness of lower limbs. Magnetic resonance imaging (MRI) of the brain and spinal cord showed multiple ill-defined hyperintensities, suggestive of demyelination. The clinical presentation, MRI findings, cerebrospinal fluid examination, negative anti-aquaporin-4 antibody and metabolic and other viral infectious screening supported the diagnosis of ADEM. The patient had transiently positive anti-MOG antibodies (for 3 months) and was treated with intravenous immunoglobulin followed by oral prednisolone for 3 months. There was a significant recovery in the upper limb weakness and brainstem function. This case highlights the association of anti-MOG antibody with ADEM following viral infections and the need for prolonged follow-up to differentiate between transient antibodies from relapsing MOG antibody disease.

Five-year visual outcomes after optic neuritis in anti-MOG antibody-associated disease

INTRODUCTION

Optic neuritis (ON) is a major phenotype of clinical attack related to demyelinating neurological diseases of the central nervous system, including multiple sclerosis (MS), anti-aquaporin-4 (AQP4) antibody-positive neuromyelitis optica spectrum disorder (NMOSD), and anti-myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). As the concept of MOGAD is relatively new, the long-term visual outcomes after ON in MOGAD remains unclear.

METHODS

To elucidate the long-term visual prognosis after ON in MOGAD, patients with MOGAD whose visual acuity were regularly followed for more than 5 years from the onset of ON were enrolled. Best-corrected visual acuity (BCVA) at nadir in the acute phase and at 1 and 5 years from onset was evaluated. The data from patients with MOGAD were compared with those from patients with MS or anti-AQP4-positive NMOSD.

RESULTS

Twenty-three patients (31 ON-involved eyes) with MOGAD, 20 patients (24 ON-involved eyes) with MS, and 22 patients (24 ON-involved eyes) with anti-AQP4-positive NMOSD were evaluated. All BCVA at nadir, 1 year, and 5 years from the onset of ON were much worse in anti-AQP4-positive NMOSD than in MS (p = 0.0024) and MOGAD (p = 0.0014) patients. In MOGAD and anti-AQP4-positive NMOSD, the serum disease-specific antibody titer was not associated with the subsequent visual prognosis. Visual acuity had almost fully recovered spontaneously or shortly after initiating acute treatment in 22 of the 23 patients with MOGAD-ON. The administration of high-dose intravenous steroid therapy further facilitated early recovery of visual acuity. Meanwhile, a small fraction of patients with extensive optic nerve lesions involving the chiasma irreversibly experienced severe visual impairment despite appropriate acute treatment.

CONCLUSION

Although a small fraction of patients with MOGAD who presented with extensive optic nerve lesions experienced irreversible severe visual impairment, the long-term visual outcomes after 5 years from ON in patients with MOGAD were generally as good as that in patients with MS and much better than that in patients with anti-AQP4-positive NMOSD.

Myelin oligodendrocyte glycoprotein (MOG) antibody-mediated disease: The difficulty of predicting relapses

BACKGROUND

While many patients with myelin oligodendrocyte glycoprotein antibody-mediated disease (MOG-AD) will have a monophasic course, 30-80% of patients will relapse after the initial attack. It is not known which factors predict relapse. Here we describe our clinical experience with MOG-AD and evaluate for factors that correlate with relapsing disease.

METHODS

This was a retrospective, multi-institutional study of 54 patients with MOG-AD, including 17 children and 37 adults. Mann-Whitney U and Fischer's Exact tests were used for comparisons and logistic regression for correlations.

RESULTS

Incident attack phenotype included acute disseminated encephalomyelitis (15%), unilateral optic neuritis (ON; 39%), bilateral ON (24%), transverse myelitis (TM; 11%) and ON with TM (11%). Pediatric patients were more likely than adults to present with ADEM (p = .009) and less likely to present with unilateral ON (p = .04). 31 patients (57%) had a relapsing disease course, with time to first relapse of 8.2 months and median annualized relapse rate of 0.97 months. In 40% of patients (n = 22) the first relapse occurred following the withdrawal of treatment for the incident attack. 5 patients converted to seronegative at follow up, 2 of whom later relapsed. Logistic regression revealed no significant relationship between age, gender, race, presentation phenotype, antibody titer, or cerebrospinal fluid results with risk of relapse. For patients who started disease modifying therapy (DMT) prior to the first relapse (n = 11), 64% remained monophasic. 50% (n = 15) of patients on DMT continued to have disease activity, requiring treatment adjustment.

CONCLUSIONS

It is difficult to predict which patients with MOG-AD will relapse. Research is needed to determine the optimal timing and choice of treatment.

Assessing attacks and treatment response rates among adult patients with NMOSD and MOGAD: Data from a nationwide registry in Argentina

We aimed to examine treatment interventions implemented in patients experiencing neuromyelitis optica spectrum disorders (NMOSD) attacks (frequency, types, and response).

Myelin-oligodendrocyte glycoprotein antibody-associated disease

Myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a recently identified autoimmune disorder that presents in both adults and children as CNS demyelination. Although there are clinical phenotypic overlaps between MOGAD, multiple sclerosis, and aquaporin-4 antibody-associated neuromyelitis optica spectrum disorder (NMOSD) cumulative biological, clinical, and pathological evidence discriminates between these conditions. Patients should not be diagnosed with multiple sclerosis or NMOSD if they have anti-MOG antibodies in their serum. However, many questions related to the clinical characterisation of MOGAD and pathogenetic role of MOG antibodies are still unanswered. Furthermore, therapy is mainly based on standard protocols for aquaporin-4 antibody-associated NMOSD and multiple sclerosis, and more evidence is needed regarding how and when to treat patients with MOGAD.

Spectrum of anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab)-associated diseases: an Indian perspective

Myelin oligodendrocyte glycoprotein antibody (MOG-Ab) is involved in the pathogenesis of central nervous system (CNS) demyelination disorders. We aimed to explore the spectrum of MOG-Ab-associated diseases in eastern India. A single-center, prospective observational study was done over a period of 2 years in a tertiary care hospital of eastern India. Patients with CNS demyelination disorders who tested positive for MOG-Ab using live cell-based assay were included in the study; while, those with age less than 1 year, documented preexisting CNS structural lesions, developmental delays or diagnosed multiple sclerosis were excluded. Demographic profile, clinical spectrum, disease course, radiological features as well as response to treatment were analyzed among included patients. Twenty MOG-Ab-positive patients were included (M:F 1:1.85). The median age of symptom onset was 10.5 years. The median follow-up of patients was 13 months. Acute disseminated encephalomyelitis (ADEM) was the commonest presentation at first attack (55%), followed by optic neuritis (ON) (45%). Patients with ADEM had a significantly lower age at first attack (p = 0.025). Monophasic and relapsing disease courses were seen in 45% and 55% patients, respectively. While all patients with only ADEM had a monophasic course, 77.8% with ON had a relapsing course. Among patients who presented with isolated transverse myelitis, 75% had a monophasic course and all had disease confined to the spinal cord. Good response to corticosteroids was seen in majority of participants. Second-line drugs were needed in 55% patients, rituximab being the commonest second-line agent used. 35% patients had significant disability (EDSS > 4) at last follow-up. MOG-Ab-associated diseases have diverse clinical phenotypes characterized by age-dependent pattern-specific courses.

Pathogenesis of autoimmune demyelination: from multiple sclerosis to neuromyelitis optica spectrum disorders and myelin oligodendrocyte glycoprotein antibody-associated disease

Autoimmunity plays a significant role in the pathogenesis of demyelination. Multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein antibody‐associated disease (MOGAD) are now recognised as separate disease entities under the amalgam of human central nervous system demyelinating disorders. While these disorders share inherent similarities, investigations into their distinct clinical presentations and lesion pathologies have aided in differential diagnoses and understanding of disease pathogenesis. An interplay of various genetic and environmental factors contributes to each disease, many of which implicate an autoimmune response. The pivotal role of the adaptive immune system has been highlighted by the diagnostic autoantibodies in NMOSD and MOGAD, and the presence of autoreactive lymphocytes in MS lesions. While a number of autoantigens have been proposed in MS, recent emphasis on the contribution of B cells has shed new light on the well‐established understanding of T cell involvement in pathogenesis. This review aims to synthesise the clinical characteristics and pathological findings, discuss existing and emerging hypotheses regarding the aetiology of demyelination and evaluate recent pathogenicity studies involving T cells, B cells, and autoantibodies and their implications in human demyelination.

Cells to the Rescue: Emerging Cell-Based Treatment Approaches for NMOSD and MOGAD

Cell-based therapies are gaining momentum as promising treatments for rare neurological autoimmune diseases, including neuromyelitis optica spectrum disorders and myelin oligodendrocyte glycoprotein antibody-associated disease. The development of targeted cell therapies is hampered by the lack of adequate animal models that mirror the human disease. Most cell-based treatments, including HSCT, CAR-T cell, tolerogenic dendritic cell and mesenchymal stem cell treatment have entered early stage clinical trials or have been used as rescue treatment in treatment-refractory cases. The development of antigen-specific cell-based immunotherapies for autoimmune diseases is slowed down by the rarity of the diseases, the lack of surrogate outcomes and biomarkers that are able to predict long-term outcomes and/or therapy effectiveness as well as challenges in the manufacturing of cellular products. These challenges are likely to be overcome by future research.

Comparison of MRI Lesion Evolution in Different Central Nervous System Demyelinating Disorders

BACKGROUND AND OBJECTIVE

There are few studies that compare lesion evolution across different CNS demyelinating diseases, yet knowledge of this may be important for diagnosis and understanding differences in disease pathogenesis. We sought to compare MRI T2-lesion evolution in myelin-oligodendrocyte-glycoprotein-IgG-associated disorder (MOGAD), aquaporin-4-IgG-positive neuromyelitis optica spectrum disorder (AQP4-IgG-NMOSD), and multiple sclerosis (MS).

METHODS

In this descriptive study, we retrospectively identified Mayo Clinic patients with MOGAD, AQP4-IgG-NMOSD, or MS and: 1) brain or myelitis attack; 2) available attack MRI within 6 weeks; and 3) follow-up MRI beyond 6 months without interval relapses in that region. Two neurologists identified the symptomatic or largest T2-lesion for each patient (index lesion). MRIs were then independently reviewed by two neuroradiologists blinded to diagnosis to determine resolution of T2-lesions by consensus. The index T2-lesion area was manually outlined acutely and at follow-up to assess variation in size.

RESULTS

We included 156 patients (MOGAD, 38; AQP4-IgG-NMOSD, 51; MS, 67) with 172 attacks (brain, 81; myelitis, 91). The age (median [range]) differed between MOGAD (25 [2-74]), AQP4-IgG-NMOSD (53 [10-78]) and MS (37 [16-61]) (p<0.01) and female sex predominated in the AQP4-IgG-NMOSD (41/51 [80%]) and MS (51/67 [76%]) groups but not among those with MOGAD (17/38 [45%]). Complete resolution of the index T2-lesion was more frequent in MOGAD (brain, 13/18[72%]; spine, 22/28[79%]) than AQP4-IgG-NMOSD (brain, 3/21[14%]; spine, 0/34[0%]) and MS (brain, 7/42[17%]; spine, 0/29[0%]), p<0.001. Resolution of all T2-Lesions occurred most often in MOGAD (brain, 7/18[39%]; spine, 22/28[79%]) than AQP4-IgG-NMOSD (brain, 2/21[10%]; spine, 0/34[0%]), and MS (brain, 2/42[5%]; spine, 0/29[0%]), p< 0.01. There was a larger median (range) reduction in T2-lesion area in mm² on follow-up axial brain MRI with MOGAD (213[55-873]) than AQP4-IgG-NMOSD (104[0.7-597]) (p=0.02) and MS, 36[0-506]) (p< 0.001) and the reductions in size on sagittal spine MRI follow-up in MOGAD (262[0-888]) and AQP4-IgG-NMOSD (309[0-1885]) were similar (p=0.4) and greater than MS (23[0-152]) (p<0.001).

CONCLUSIONS

The MRI T2-lesions in MOGAD resolve completely more often than AQP4-IgG-NMOSD and MS. This has implications for diagnosis, monitoring disease activity, and clinical trial design, while also providing insight into pathogenesis of central nervous system demyelinating diseases.

Emerging Exosomes and Exosomal MiRNAs in Spinal Cord Injury

Acute spinal cord injury (SCI) is a serious traumatic event to the spinal cord with considerable morbidity and mortality. This injury leads to short- and long-term variations in the spinal cord, and can have a serious effect on the patient's sensory, motor, or autonomic functions. Due to the complicated pathological process of SCI, there is currently no successful clinical treatment strategy. Exosomes, extracellular vesicles (EVs) with a double-layer membrane structure of 30-150 nm diameter, have recently been considered as critical mediators for communication between cells and tissues by transferring proteins, lipids, and nucleic acids. Further studies verified that exosomes participate in the pathophysiological process of several diseases, including cancer, neurodegenerative diseases, and cardiovascular diseases, and could have a significant impact in their treatment. As natural carriers of biologically active cargos, exosomes have emerged as pathological mediators of SCI. In this review article, we critically discuss the functions of exosomes as intracellular mediators and potential treatments in SCI and provide an outlook on future research.

Antibody-Mediated Autoimmune Diseases of the CNS: Challenges and Approaches to Diagnosis and Management

Antibody-mediated disorders of the central nervous system (CNS) are increasingly recognized as neurologic disorders that can be severe and even life-threatening but with the potential for reversibility with appropriate treatment. The expanding spectrum of newly identified autoantibodies targeting glial or neuronal (neural) antigens and associated clinical syndromes (ranging from autoimmune encephalitis to CNS demyelination) has increased diagnostic precision, and allowed critical reinterpretation of non-specific neurological syndromes historically associated with systemic disorders (e.g., Hashimoto encephalopathy). The intracellular vs. cell-surface or synaptic location of the different neural autoantibody targets often helps to predict the clinical characteristics, potential cancer association, and treatment response of the associated syndromes. In particular, autoantibodies targeting intracellular antigens (traditionally termed onconeural autoantibodies) are often associated with cancers, rarely respond well to immunosuppression and have a poor outcome, although exceptions exist. Detection of neural autoantibodies with accurate laboratory assays in patients with compatible clinical-MRI phenotypes allows a definite diagnosis of antibody-mediated CNS disorders, with important therapeutic and prognostic implications. Antibody-mediated CNS disorders are rare, and reliable autoantibody identification is highly dependent on the technique used for detection and pre-test probability. As a consequence, indiscriminate neural autoantibody testing among patients with more common neurologic disorders (e.g., epilepsy, dementia) will necessarily increase the risk of false positivity, so that recognition of high-risk clinical-MRI phenotypes is crucial. A number of emerging clinical settings have recently been recognized to favor development of CNS autoimmunity. These include antibody-mediated CNS disorders following herpes simplex virus encephalitis or occurring in a post-transplant setting, and neurological autoimmunity triggered by TNFα inhibitors or immune checkpoint inhibitors for cancer treatment. Awareness of the range of clinical and radiological manifestations associated with different neural autoantibodies, and the specific settings where autoimmune CNS disorders may occur is crucial to allow rapid diagnosis and early initiation of treatment.

Autoimmune Brainstem Encephalitis: An Illustrative Case and a Review of the Literature

Autoimmune brainstem encephalitis (BSE) is a rare neurological condition with a wide range of underlying etiologies. It can be subdivided into two broad groups: a primary inflammatory disease of the central nervous system (CNS) or a brainstem disorder secondary to systemic diseases where the CNS is only one of many affected organs. Symptoms range from mild to life-threatening manifestations. Most cases respond well to immunotherapy. Therefore, broad and in-depth knowledge of the various inflammatory disorders that target the brainstem is essential for guiding the diagnostic approach and assisting in early initiation of appropriate therapy. We herein report on a case of BSE and provide an overview of the various causes of autoimmune BSE with an emphasis on the clinical manifestations and diagnostic approach.

Brain structural alterations in MOG antibody diseases: a comparative study with AQP4 seropositive NMOSD and MS

BACKGROUND

Brain structural alterations and their clinical significance of myelin oligodendrocyte glycoprotein antibody disease (MOGAD) have not been determined.

METHODS

We recruited 35 MOGAD, 38 aquaporin 4 antibody positive neuromyelitis optica spectrum diseases (AQP4+ NMOSD), 37 multiple sclerosis (MS) and 60 healthy controls (HC) who underwent multimodal brain MRI from two centres. Brain lesions, volumes of the whole brain parenchyma, cortical and subcortical grey matter (GM), brainstem, cerebellum and cerebral white matter (WM) and diffusion measures (fractional anisotropy, FA and mean diffusivity, MD) were compared among the groups. Associations between the MRI measurements and the clinical variables were assessed by partial correlations. Logistic regression was performed to differentiate MOGAD from AQP4+ NMOSD and MS.

RESULTS

In MOGAD, 19 (54%) patients had lesions on MRI, with cortical/juxtacortical (68%) as the most common location. MOGAD and MS showed lower cortical and subcortical GM volumes than HC, while AQP4+ NMOSD only demonstrated a decreased cortical GM volume. MS demonstrated a lower cerebellar volume, a lower FA and an increased MD than MOGAD and HC. The subcortical GM volume was negatively correlated with Expanded Disability Status Scale in MOGAD (R=-0.51; p=0.004). A combination of MRI and clinical measures could achieve an accuracy of 85% and 93% for the classification of MOGAD versus AQP4+ NMOSD and MOGAD versus MS, respectively.

CONCLUSION

MOGAD demonstrated cortical and subcortical atrophy without severe WM rarefaction. The subcortical GM volume correlated with clinical disability and a combination of MRI and clinical measures could separate MOGAD from AQP4+ NMOSD and MS.

Aseptic meningitis and leptomeningeal enhancement associated with anti-MOG antibodies: A review

BACKGROUND

Aseptic meningitis can be caused by autoimmune diseases, such as lupus and sarcoidosis. Aseptic meningitis with leptomeningeal enhancement can be the initial presentation of a neuroinflammatory syndrome associated with antibodies to myelin oligodendrocyte glycoprotein (MOG-abs). MOG-abs is a serum biomarker for MOG-associated disorder (MOG-AD), an acquired demyelinating syndrome that includes features of neuromyelitis optica, multiple sclerosis, optic neuritis, and acute disseminated encephalomyelitis. The purpose of this study is to review cases of aseptic meningitis and leptomeningeal enhancement associated with MOG-abs.

METHODS

Systematic review using PubMed, Embase, Ovid MEDLINE, Web of Science Core Collection, and Google Scholar up to December 2020 was performed. Cases of MOG-AD were included if they met the following criteria: 1) Initial clinical presentation of aseptic meningitis; 2) positive leptomeningeal enhancement and 3) MOG-Ab seropositivity. Descriptive statistics were used. This analysis was limited to the cases available in the literature.

RESULTS

11 total cases of aseptic meningitis and leptomeningeal enhancement in setting of MOG-ab were identified. Demyelinating type T2 lesions were also present at time of presentation in 6/11; however, 5/11 of patients had leptomeningeal enhancement alone without demyelinating lesions. All 5 patients required immunotherapy for improvement, including one patient with symptoms for 28 days, with 4/5 receiving steroids and 1/5 receiving intravenous immunoglobulin (IVIG).

CONCLUSIONS

Aseptic meningitis with leptomeningeal enhancement can be the initial presenting symptom of MOG-AD. MOG-ab testing should be considered in a patient presenting with aseptic meningitis and leptomeningeal enhancement of unknown etiology.

Frequency of myelin oligodendrocyte glycoprotein antibodies in a large cohort of neurological patients

Background

Myelin oligodendrocyte glycoprotein (MOG) antibody disease (MOG-AD) is recognized as a distinct nosological entity. IgG antibodies against MOG (MOG-Ab) overlap with neuromyelitis optica spectrum disorders (NMOSD) phenotype in adults. However, an increasing number of clinical phenotypes have been reported to be associated with MOG-Ab.

Objective

To investigate the seroprevalence of MOG-Ab under consideration of demographics, disease entities and time course in a large cohort of unselected neurological patients.

Methods

Blood samples of 2.107 consecutive adult neurologic patients admitted to our department between 2016-2017 were tested for MOG-Ab using a cell-based assay. MOG-Ab persistence was analyzed in follow-up samples. External validation was performed in two independent laboratories.

Results

We found MOG-Ab in 25 of 2.107 (1.2%) patients. High antibody ratios were mostly associated with NMOSD and MOG-AD phenotype (5/25). Low ratios occurred in a wide range of neurological diseases, predominantly in other demyelinating CNS diseases (5/25) and stroke (6/25). MOG-Ab persistence over time was not confined to NMOSD and MOG-AD phenotype.

Conclusion

The present study demonstrates the occurrence of MOG-Ab in a wide range of neurological diseases. Only high MOG-Ab ratios were associated with a defined clinical phenotype, but low MOG-Ab ratios were not. The diagnostic value of low MOG-Ab is thus highly limited.

Patient-reported burden of symptoms in neuromyelitis optica: A secondary analysis on pain and quality of life

INTRODUCTION

Relapses of neuromyelitis optica spectrum disorder (NMOSD) result in cumulative neurologic disabilities, are unpredictable, and are interspersed with remissions. Pain in NMOSD is often severe and intractable, with a significant impact on patient quality of life (QoL). We performed a more detailed analysis of previously published survey data on the association of pain and QoL, comparing patients who were seropositive and seronegative for antibodies against aquaporin-4 (AQP4-IgG).

METHODS

We conducted a secondary analysis of questionnaire data from 193 NMOSD patients across North America. The study population was predominantly female (88.6%) and aged 19-76 years. Results were reported for three groups: AQP4-IgG-seropositive (61.1%), AQP4-IgG-seronegative and the total cohort including patients with unknown serostatus. We measured the strength of associations and interactions between pain and variables including QoL, patient satisfaction, frequency of hospital visits, and number of relapses versus other symptoms.

RESULTS

Pain severity was the strongest negative predictor of QoL. In the total and AQP4-IgG-seropositive groups, pain was the most common symptom that patients wanted their physician to be concerned about; in the AQP4-IgG-seronegative group, this was fatigue. For all patients, frequent hospital visits and relapses were associated with more severe pain, but not frequency of NMOSD specialist visits. Patients without recent relapse still commonly reported moderate or severe pain (>25%).

CONCLUSION

This study confirms the heavy burden of pain on NMOSD patients and its effect on QoL and healthcare utilization. Prevention or early treatment of relapses and more effective pain management may reduce this burden.

Short- and Long-Lived Autoantibody-Secreting Cells in Autoimmune Neurological Disorders

As B cells differentiate into antibody-secreting cells (ASCs), short-lived plasmablasts (SLPBs) are produced by a primary extrafollicular response, followed by the generation of memory B cells and long-lived plasma cells (LLPCs) in germinal centers (GCs). Generation of IgG4 antibodies is T helper type 2 (Th2) and IL-4, -13, and -10-driven and can occur parallel to IgE, in response to chronic stimulation by allergens and helminths. Although IgG4 antibodies are non-crosslinking and have limited ability to mobilize complement and cellular cytotoxicity, when self-tolerance is lost, they can disrupt ligand-receptor binding and cause a wide range of autoimmune disorders including neurological autoimmunity. In myasthenia gravis with predominantly IgG4 autoantibodies against muscle-specific kinase (MuSK), it has been observed that one-time CD20⁺ B cell depletion with rituximab commonly leads to long-term remission and a marked reduction in autoantibody titer, pointing to a short-lived nature of autoantibody-secreting cells. This is also observed in other predominantly IgG4 autoantibody-mediated neurological disorders, such as chronic inflammatory demyelinating polyneuropathy and autoimmune encephalitis with autoantibodies against the Ranvier paranode and juxtaparanode, respectively, and extends beyond neurological autoimmunity as well. Although IgG1 autoantibody-mediated neurological disorders can also respond well to rituximab induction therapy in combination with an autoantibody titer drop, remission tends to be less long-lasting and cases where titers are refractory tend to occur more often than in IgG4 autoimmunity. Moreover, presence of GC-like structures in the thymus of myasthenic patients with predominantly IgG1 autoantibodies against the acetylcholine receptor and in ovarian teratomas of autoimmune encephalitis patients with predominantly IgG1 autoantibodies against the N‐methyl‐d‐aspartate receptor (NMDAR) confers increased the ability to generate LLPCs. Here, we review available information on the short-and long-lived nature of ASCs in IgG1 and IgG4 autoantibody-mediated neurological disorders and highlight common mechanisms as well as differences, all of which can inform therapeutic strategies and personalized medical approaches.

Differential Binding of Autoantibodies to MOG Isoforms in Inflammatory Demyelinating Diseases

OBJECTIVE

To analyze serum immunoglobulin G (IgG) antibodies to major isoforms of myelin oligodendrocyte glycoprotein (MOG-alpha 1-3 and beta 1-3) in patients with inflammatory demyelinating diseases.

METHODS

Retrospective case-control study using 378 serum samples from patients with multiple sclerosis (MS), patients with non-MS demyelinating disease, and healthy controls with MOG alpha-1-IgG positive (n = 202) or negative serostatus (n = 176). Samples were analyzed for their reactivity to human, mouse, and rat MOG isoforms with and without mutations in the extracellular MOG Ig domain (MOG-ecIgD), soluble MOG-ecIgD, and myelin from multiple species using live cell-based, tissue immunofluorescence assays and ELISA.

RESULTS

The strongest IgG reactivities were directed against the longest MOG isoforms alpha-1 (the currently used standard test for MOG-IgG) and beta-1, whereas the other isoforms were less frequently recognized. Using principal component analysis, we identified 3 different binding patterns associated with non-MS disease: (1) isolated reactivity to MOG-alpha-1/beta-1 (n = 73), (2) binding to MOG-alpha-1/beta-1 and at least one other alpha, but no beta isoform (n = 64), and (3) reactivity to all 6 MOG isoforms (n = 65). The remaining samples were negative (n = 176) for MOG-IgG. These MOG isoform binding patterns were associated with a non-MS demyelinating disease, but there were no differences in clinical phenotypes or disease course. The 3 MOG isoform patterns had distinct immunologic characteristics such as differential binding to soluble MOG-ecIgD, sensitivity to MOG mutations, and binding to human MOG in ELISA.

CONCLUSIONS

The novel finding of differential MOG isoform binding patterns could inform future studies on the refinement of MOG-IgG assays and the pathophysiologic role of MOG-IgG.

Structural and Functional Alterations in Visual Pathway After Optic Neuritis in MOG Antibody Disease: A Comparative Study With AQP4 Seropositive NMOSD

Background: Optic neuritis (ON) is an important clinical manifestation of neuromyelitis optic spectrum disease (NMOSD). Myelin oligodendrocyte glycoprotein (MOG) antibody-related and aquaporin 4 (AQP4) antibody-related ON show different disease patterns. The aim of this study was to explore the differences in structure and function of the visual pathway in patients with ON associated with MOG and AQP4 antibodies.

Methods: In this prospective study, we recruited 52 subjects at Beijing Tiantan Hospital, including 11 with MOG Ig+ ON (MOG-ON), 13 with AQP4 Ig+ ON (AQP4-ON), and 28 healthy controls (HCs). Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of optic radiation (OR), primary visual cortex volume (V1), brain volume, and visual acuity (VA) were compared among groups. A multiple linear regression was used to explore associations between VA and predicted factors. In addition, we used optical coherence tomography (OCT) to examine thickness of the peripapillary retinal nerve fiber layer (pRNFL) and retinal ganglion cell complex (GCC) in a separate cohort consisting of 15 patients with ON (8 MOG-ON and 7 AQP4-ON) and 28 HCs.

Results: Diffusion tensor imaging showed that the FA of OR was lower than controls in patients with AQP4-ON (p = 0.001) but not those with MOG-ON (p = 0.329) and was significantly different between the latter two groups (p = 0.005), while V1 was similar in patients with MOG-ON and AQP4-ON (p = 0.122), but was lower than controls in AQP4-ON (p = 0.002) but not those with MOG-ON (p = 0.210). The VA outcomes were better in MOG-ON than AQP4-ON, and linear regression analysis revealed that VA in MOG-ON and AQP4-ON was both predicted by the FA of OR (standard β = −0.467 and −0.521, p = 0.036 and 0.034). Both patients of MOG-ON and AQP4-ON showed neuroaxonal damage in the form of pRNFL and GCC thinning but showed no statistically significant difference (p = 0.556, 0.817).

Conclusion: The structural integrity of OR in patients with MOG-ON, which is different from the imaging manifestations of AQP4-ON, may be a reason for the better visual outcomes of patients with MOG-ON.

Optic Neuritis in a Patient with Seropositive Myelin Oligodendrocyte Glycoprotein Antibody During the Post-COVID-19 Period

Reports of neuro-ophthalmological manifestations and complications in patients with coronavirus disease 19 (COVID-19) are still scarce. The aim of this article is to present optic neuritis, as possible post-infectious manifestation of COVID-19. Four weeks after hospitalization for seropositive coronavirus disease 19 (COVID-19), presented as bilateral bronchopneumonia, with radiology and laboratory findings also pointed to high clinical suspicion to COVID-19, a 63-year-old man developed a headache and subacute and profound visual loss on his right eye. The disease presentation was the right eye papillitis. Inflammatory parameters were normal at the time of hospitalization, and IgM and IgG for SARS-CoV-2 were still positive. After corticosteroid pulse therapy, his vision improved significantly and on follow-up visits returned to normal. All laboratory and radiology findings were unremarkable, except for antibodies against SARS-CoV-2 and myelin oligodendrocyte glycoprotein (MOG). We discuss about capacity of SARS-CoV-2 to cause optic neuritis and possible significance of MOG antibodies in similar cases.

Targeted Expression of Myelin Autoantigen in the Periphery Induces Antigen-Specific T and B Cell Tolerance and Ameliorates Autoimmune Disease

There is a great interest in developing antigen-specific therapeutic approaches for the treatment of autoimmune diseases without compromising normal immune function. The key challenges are to control all antigen-specific lymphocyte populations that contribute to pathogenic inflammatory processes and to provide long-term protection from disease relapses. Here, we show that myelin oligodendrocyte glycoprotein (MOG)-specific tolerance can be established by ectopic expression of MOG in the immune organs. Using transgenic mice expressing MOG-specific CD4, CD8, and B cell receptors, we show that MOG expression in the bone marrow cells results in impaired development of MOG-specific lymphocytes. Ectopic MOG expression has also resulted in long-lasting protection from MOG-induced autoimmunity. This finding raises hope that transplantation of autoantigen-expressing bone marrow cells as a therapeutic strategy for specific autoantigen-driven autoimmune diseases.

Neuropsychological Phenotypes of Pediatric Anti-Myelin Oligodendrocyte Glycoprotein Associated Disorders: A Case Series

Emerging research has demonstrated that anti-myelin oligodendrocyte associated disorders (MOG-AD) are associated with a less severe clinical course than demyelinating conditions associated with the presence of aquaporin-4 antibodies. While a heterogeneity of neuropsychological outcomes in pediatric demyelinating conditions have been described in the literature, no studies to date have investigated the neuropsychological sequelae of pediatric MOG-AD specifically. The objective of the present case series was to describe the clinical and neuropsychological phenotypes of seven pediatric patients (ages 3-15 years) with MOG-AD of different diagnoses (e.g., acute disseminated encephalomyelitis, optic neuritis, multiple sclerosis, and neuromyelitis spectrum disorders). Neuropsychological outcomes were evaluated by retrospective chart review. Results indicated largely intact neuropsychological profiles in five of the seven patients, with mild weaknesses in attention, executive functioning, processing speed, visual-motor/fine-motor skills, and mood concerns being observed. Two patients with a Kurtzke Extended Disability Status Scale of 0 still demonstrated findings on neuropsychological testing. Of the other two patients, one demonstrated higher levels of impairment in the context of a complex medical history and premorbid learning difficulties, while the other demonstrated declines in functioning likely associated with an earlier age of onset. Findings suggest that neuropsychological outcomes may be correspondingly less severe in this population compared with what has previously been described in the pediatric demyelinating disease literature. This differential impact may contribute to the heterogeneity of neuropsychological outcomes found in previous studies, and future research should separate participants with myelin oligodendrocyte antibodies given the difference in clinical course, treatment outcomes, and neuropsychological sequelae.

Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease: Presentation, Diagnosis, and Management

Pediatric demyelinating syndromes are a spectrum of diseases affecting the central nervous system. In the past decade, major advances have been made in this field, including the discovery of antibody-based biomarkers and treatment guidelines for specific syndromes. When myelin oligodendrocyte glycoprotein (MOG) antibodies were first discovered, they were thought to be a biomarker for multiple sclerosis (MS). However, further research has shown that MOG positivity during the first episode of a pediatric demyelinating syndrome is a predictor of a course that is distinct to MS. This article discusses the clinical manifestations of MOG antibody associated disease and key distinguishing features in the investigation, treatment, and prognosis between MOG and other demyelinating diseases. [Pediatr Ann. 2021;50(6):e254-e258.].

F-18 Fluorodeoxyglucose Positron Emission Tomography Metabolic Phenotype in Myelin Oligodendrocyte Glycoprotein Antibody-Positive Autoimmune Epilepsy

We describe the metabolic phenotype on F-18 fluorodeoxyglucose positron emission tomography (PET) in a 13-year-old female with myelin oligodendrocyte glycoprotein (MOG) antibody–positive encephalitis. Unilateral hemispheric hypometabolism on PET may be the metabolic phenotype of autoimmune epilepsy associated with MOG antibody.

[Herpesviruses and biomarkers in disseminated encephalomyelitis and multiple sclerosis in children (part II)]

Recently, the problem of demyelinating diseases in children is still very acute. This occurs, on the one hand, by high access and specificity of diagnostic methods and, on the other hand - by high morbidity of children different neuroinfectious diseases which can lead to demyelinating diseases. This literature review presents the currently available information on the autoantibodies and neurospecific protein role in the development of multiple sclerosis and acute disseminative encephalitis in children. The authors also describe their experience of complex etiopatogenic therapy and cytoflavin use that helps to reduce frequency and expression of demyelinating process and endothelium dysfunction in case of active herpesvirus infection.

The occurrence of myelin oligodendrocyte glycoprotein antibodies in aquaporin-4-antibody seronegative Neuromyelitis Optica Spectrum Disorder: A systematic review and meta-analysis

BACKGROUND

Despite inclusion in neuromyelitis optica spectrum disorders (NMOSD), myelin oligodendrocyte glycoprotein antibody (MOG-Ab)-associated diseases are increasingly recognized as an independent disease entity. In this study, we conducted a systematic review and meta-analysis to comprehensively update the rate of occurrence of MOG-Ab in Aquaporin4 (AQP4)-antibody seronegative NMOSD.

METHODS

We searched PubMed, EMBASE, and Cochrane databases for studies reporting the rates of patients with MOG-Ab in NMOSD. Fixed or random-effects models were used to pool results across studies.

RESULTS

Fourteen studies met the inclusion criteria. Overall, MOG-Abs positive patients comprised 9.3% of all NMO/NMOSD (95% confidence interval [CI] 7.9%-10.8%, I² = 13.1%), 32.5% of all AQP4-Ab seronegative NMO/NMOSD (95% CI 25.7%-39.3%, I² = 45.8%), and 41.6% of AQP4-Ab seronegative NMOSD cases diagnosed by IPND 2015 criteria (95% CI 35.1%-48.2%, I² = 0.0%). The pooled prevalence of MOG-Ab was 31.0% among Asian AQP4-Ab seronegative NMO/NMOSD patients (95% CI 22.1%-39.9% I²=54.1%) and 34.3% in European seronegative NMO/NMOSD (95% CI 21.9%-46.7%, I² = 51.9%).

CONCLUSIONS

This study shows that MOG-Abs represent a substantial proportion of AQP4-Ab seronegative NMOSD patients despite different underlying mechanisms, clinical manifestations, and treatment response, suggesting MOG-Ab screening in AQP4-Ab seronegative NMOSD patients can facilitate accurate diagnoses and treatments.

The Clinical, Radiologic, and Prognostic Differences Between Pediatric and Adult Patients With Myelin Oligodendrocyte Glycoprotein Antibody-Associated Encephalomyelitis

Purpose: To evaluate the clinical differences between pediatric and adult patients with myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis (MOG-EM).

Methods: We retrospectively reviewed the clinical features of pediatric and adult patients with MOG-EM in our center between November 2015 and October 2020.

Results: Twenty-eight pediatric patients and 25 adults were admitted to our study. Bilateral optic neuritis (BON) was the most common initial phenotype in the pediatric group but less common in the adult group (28.57 vs. 0%, p = 0.0119). Almost half of the adult patients presented with neuromyelitis optica spectrum disease (NMOSD), which was less prevalent among the pediatrics (48 vs. 21.43%, p = 0.0414). Visual impairment was the most common symptom in both groups during the initial attack (pediatric group, 39.29%; adult group, 64%) and throughout the full course (pediatric group, 57.14%; adult group, 72%). More pediatric patients suffered from fever than adult patients at onset (pediatric group, 28.57%; adult group, 4%; p = 0.0442) and throughout the full course (pediatric group, 39.29%; adult group, 12%; p = 0.0245). Multiple patchy lesions in subcortical white matter (pediatric group, 40.74%; adult group, 45%), periventricular (pediatric group, 25.93%; adult group, 35%), infratentorial (pediatric group, 18.52%; adult group, 30%) and deep gray matter (pediatric group, 25.93%; adult group, 20%) were frequent in all cases, no significant difference was found between the two groups, while bilateral optic nerve involvement was more frequent in pediatric group (61.54 vs. 14.29%, p = 0.0042) and unilateral optic nerve involvement was higher in adult group (64.29 vs. 15.38%, p = 0.0052). At the last follow-up, adult patients had a higher average EDSS score (median 1.0, range 0–3) than pediatrics (median 0.0, range 0–3), though not significant (p = 0.0752). Patients aged 0–9 years (61.54%) and 10–18 years (70%), and patients presenting with encephalitis/meningoencephalitis (100%) and ADEM (75%) were more likely to recover fully.

Conclusions: Visual impairment was the dominant symptom in both pediatric and adult patients, while fever was more frequent in pediatric patients. Data suggested that BON and bilateral optic nerve involvement were more common in pediatric cases whereas NMOSD and unilateral optic nerve involvement were more prevalent in adults. The younger patients and patients presenting with encephalitis/meningoencephalitis and ADEM tended to recover better.

Improving laboratory diagnostics in myasthenia gravis

Introduction: Myasthenia gravis (MG) is a prototypical autoimmune disease, characterized by pathogenic autoantibodies targeting structures of the neuromuscular junction. Radioimmunoprecipitation assays (RIPAs) represent the gold standard for their detection. However, new methods are emerging to complement, or overcome RIPAs, also with the perspective of eliminating the use of radioactive reagents.Areas covered: We discuss advances in laboratory methods, prompted especially by cell-based assays (CBAs), for the detection of the autoantibodies of MG diagnostics, above all those to the nicotinic acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low molecular-weight receptor-related low-density lipoprotein-4 (LRP4).Expert opinion: CBA technology makes AChRs aggregate on cell membranes, thus allowing to detect autoantibodies to clustered AChRs, with reduction of seronegative MG cases. The diagnostic relevance of RIPA/CBA-measurable LRP4 antibodies is still unclear, in Caucasian patients at least. Live CBAs for the detection of AChR, MuSK, and LRP4 antibodies might represent an alternative to RIPAs, but first require full validation. CBAs could be used as screening tests, limiting RIPAs for antibody quantification. To this end, ELISAs might be an alternative.Fixation procedures preserving enough degree of antigen conformationality could yield AChR and MuSK CBAs suitable for a wide use in clinical-chemistry laboratories.

No strong HLA association with MOG antibody disease in the UK population

Improvements in assays for detecting serum antibodies against myelin oligodendrocyte glycoprotein (MOG) have led to the appreciation of MOG‐antibody‐associated disease (MOGAD) as a novel disorder. However, much remains unknown about its etiology. We performed human leukocyte antigen (HLA) analysis in 82 MOGAD patients of European ancestry in the UK population. No HLA class II associations were observed, thus questioning the mechanism of anti‐MOG antibody generation. A weak protective association of HLA‐C*03:04 was observed (OR = 0.26, 95% CI = 0.10‐0.71, p_c = 0.013), suggesting a need for continued efforts to better understand MOGAD genetics and pathophysiology.

Myelin oligodendrocyte glycoprotein antibody-associated optic neuritis in a COVID-19 patient: A case report

RATIONALE

Coronavirus disease 2019 (COVID-19) has spread worldwide. It involves multiple organs of infected individuals and encompasses diverse clinical manifestations. We report a case of acute optic neuritis (ON) associated with myelin oligodendrocyte glycoprotein (MOG) antibody possibly induced by COVID-19.

PATIENT CONCERNS

A 47-year-old man presented to our clinic with left eye pain and vision loss. Magnetic resonance imaging of the orbit revealed the bilateral high intensity of the optic nerve sheaths. He tested positive for COVID-19 by polymerase chain reaction (PCR) testing on the day of admission but he had no signs of respiratory illness. Laboratory testing revealed that MOG immunoglobulin G (MOG IgG) was positive, but other antibodies including aquaporin-4 were negative.

DIAGNOSIS

The patient was diagnosed with MOG antibody-positive acute ON possibly induced by COVID-19.

INTERVENTIONS

Steroid pulse therapy consisting of methylprednisolone 1 g/day for a total of 3 days, followed by an oral prednisolone taper was performed.

OUTCOMES

His left eye pain was immediately relieved, and his decimal vision improved from 0.03 to 0.1 on the day of discharge. Outpatient follow-up 2 weeks later revealed left a decimal vision of 1.2, and a complete resolution of the left eye pain.

LESSONS

Our case indicated that COVID-19 might trigger an autoimmune response that leads to MOG antibody-associated ON, similar to other pathogens that were reported in the past. The treatment response to steroid pulse therapy was preferable following a typical course of MOG antibody-positive ON.

Detection of MOG-IgG in Clinical Samples by Live Cell-Based Assays: Performance of Immunofluorescence Microscopy and Flow Cytometry

Human antibodies against Myelin Oligodendrocyte Glycoprotein (MOG) from immunoglobulin-G subclasses (MOG-IgG) have been recently associated with a new subgroup of neurological autoimmune diseases with distinct clinical characteristics from multiple sclerosis and neuromyelitis optica spectrum disorders. The use of MOG-IgG as a biomarker is an essential tool to assist in the diagnosis and clinical prognosis. The cell-based assay (CBA) is a methodology that expresses high levels of natively folded human MOG protein in the cell membrane being the methodology most used for clinical MOG-IgG diagnosis. However, there is still no consensus about the best approach to perform CBA to improve the results. The CBA using flow cytometry (CBA-FC) is an automated technique with objective quantification, reducing the subject of human bias that occurred at CBA using immunofluorescence (CBA-IF). In this study, we compared the performance of CBA-IF and CBA-FC as an acquisition tool analysis. The sera of 104 patients diagnosed with inflammatory Central Nervous System diseases were tested in both CBA-IF and CBA-FC. We used the dilution of 1:128 for CBA-IF and three different dilutions (1:20, 1:100, and 1:640) for CBA-FC. The CBA-FC and CBA-IF results had 88.5% agreement between assays and the CBA-IF titers by endpoint-dilution correlated with the CBA-FC titers. The highest serum dilution resulted in an increased CBA-FC specificity, but there was a reduction in the CBA-FC sensitivity. Our study showed that CBA-FC can be used in clinical practice as a diagnostic technique for MOG-IgG. In addition, in some specific cases, the combination of both techniques could be used as a tool to discriminate unspecific binding and overcome single assay limitations.

Anti-MOG Antibody Syndrome and Cerebral Sinovenous Thrombosis: A Cause–Effect Hypothesis

Cerebral venous thrombosis is an uncommon event of stroke in childhood. Its origin is multifactorial and often it manifests with nonspecific symptoms that may overlap with underlying predisposing factors. Anti–myelin oligodendrocyte glycoprotein (MOG) antibody syndrome is a group of recently recognized acquired demyelinating diseases that occur more commonly in children, usually, with a favorable outcome. The association between cerebral venous thrombosis and demyelinating syndrome has been reported but their clinical relationship is matter of debate and various hypotheses have been advanced including intravenous (IV) steroid therapy and/or the consequence of a shared inflammatory-thrombotic process. Herein, we report the case of a child with anti-MOG antibody syndromes who developed a thrombosis of the superior sagittal sinus and of the right Trolard's vein.

New-onset epilepsy in a patient with myelin oligodendrocyte glycoprotein antibodies

In the literature, several adult cases with myelin oligodendrocyte glycoprotein (MOG) antibodies (Abs)-associated disorders have been reported to have seizure and acute disseminated encephalomyelitis (ADEM) as the main clinical manifestations, but the number is somewhat low. Because of its rarity, the clinical characteristics and a consensus on treatment have not yet been established in the adult form of ADEM and seizure phenotypes in MOG-Abs-associated disorders. In this report, we described an adult patient who presented with status epilepticus as the index event, had been suffering from chronic epilepsy, and had positive antibodies for MOG. Neither increasing the doses of the antiseizure drugs (ASDs) nor adding another new ASD reduced the prevalence of the seizures. However, he became seizure-free after the addition of azathioprine and incremental increases of methylprednisolone dosage. This case clearly indicates the effectiveness of corticosteroid and azathioprine, as well as the futility of ASDs in the management of seizure control by showing the temporal trajectory relationship among ASDs, steroids, azathioprine and seizure frequency.

Drug Treatment of Neuromyelitis Optica Spectrum Disorders: Out with the Old, in with the New?

Introduction

Neuromyelitis optica spectrum disorders (NMOSD) are rare neuroinflammatory demyelinating diseases of the CNS, mainly affecting optic nerves, spinal cord and brainstem regions. The diagnosis depends on clinical symptoms, MRI findings and the detection of autoantibodies against the water channel aquaporin 4 (AQP4-Ab). This autoantibody is particularly important for diagnostic sensitivity and specificity and further sets the course for major therapeutic decisions. Due to a relapsing course with the accumulation of disability, relapse prevention by immunotherapy is crucial in NMOSD. Until recently, disease-modifying agents specific to NMOSD were not available, and patients were treated with various immunosuppressive drugs and regimens - with variable success. Fortunately, since 2019, three new therapeutic antibodies have entered the market.

Areas Covered

We aim to shortly summarise the pathogenesis and biological targets for acute and preventive therapy of adult NMOSD. We will focus on conventional immunotherapies and the recently approved novel biological drugs satralizumab, eculizumab and inebilizumab, and conclude with a brief outlook on future therapeutic approaches.

Expert Opinion

Although satralizumab, eculizumab and inebilizumab are a breakthrough concerning short-term efficacy, important questions on their future use remain open. There is no data from head-to-head comparisons, and data on long-term safety and efficacy of the new medicines are pending. Whether any of the biologics are efficacious in AQP4-Ab negative NMOSD patients is not yet known – as is how they will succeed in non-responders to conventional immunotherapies. Further, (autoimmune) comorbidities, affordability, and market availability of drugs may be decisive factors for choosing treatments in the near future. We are fortunate to have these new drugs available now, but they will not immediately supersede established off-label drugs in this indication. It is still too early to definitively revise the treatment algorithms for NMOSD - although we are probably on the way.

Targeting interleukin-6 to treat neuromyelitis optica spectrum disorders: Implications from immunology, the FcRn pathway and clinical experience

Neuromyelitis optica spectrum disorder (NMOSD) is a rare disease of the central nervous system (CNS) that is associated with poor outcomes for patients. Until recently, when complement inhibitors were approved, there was no approved therapy. Most recently, clinical trials of interleukin-6 (IL-6) blockade showed a therapeutic benefit for NMOSD. In this review, we introduce the immunological basis of IL-6 blockade in NMOSD and summarize current knowledge about the clinical use of the IL-6 receptor inhibitors tocilizumab and satralizumab. The aim of extending the half-life of monoclonal antibodies (mAbs) has been actualized by successful clinical translation for Satralizumab, achieved via the neonatal Fc receptor (FcRn) pathway. The basic principles of FcRn are highlighted in this review together with the potential therapeutic benefits of this emerging technology.

[From neuromyelitis optica to neuromyelitis optica spectrum disorder: from clinical syndrome to diagnistic classification]

Neuromyelitis optica spectrum disorder (NMOSD), derived from NMO or Devic's disease, is considered as a distinct disease since the discovery of a novel and pathogenic serum autoantibody targeting aquaporin‑4 (AQP4-IgG) and is distinguished from classical multiple sclerosis (MS). With the continuous extension of knowledge on the clinical manifestations, the previously narrow diagnostic term NMO became NMOSD, which has also been used in the diagnostic criteria since 2015. The current diagnostic criteria enable the early diagnosis of NMOSD in patients with and without AQP4-IgG. Typical clinical manifestations include involvement of the spinal cord, optic nerve and brainstem. Typically patients with the disease also present with neuropathic pain, painful tonic spasms and also other unusual manifestations in NMOSD. Especially in AQP4-IgG positive NMOSD patients, the coexistence with other autoimmune diseases is frequently observed. In most cases NMOSD follows a relapsing course with exacerbation-free periods sometimes lasting years and can be manifested first in advanced adulthood. A subset of AQP4-IgG negative NMOSD patients have been found to harbor autoantibodies targeting myelin oligodendrocyte glycoprotein (MOG), which is considered as a distinct disease entity: these MOG antibody-associated disorders (MOGAD) can present with clinical syndromes resembling both NMOSD and MS and are currently the subject of intensive research.

Features of MOG required for recognition by patients with MOG antibody-associated disorders

Antibodies (Abs) to myelin oligodendrocyte glycoprotein (MOG) define a distinct disease entity. Here we aimed to understand essential structural features of MOG required for recognition by autoantibodies from patients. We produced the N-terminal part of MOG in a conformationally correct form; this domain was insufficient to identify patients with MOG-Abs by ELISA even after site-directed binding. This was neither due to a lack of lipid embedding nor to a missing putative epitope at the C-terminus, which we confirmed to be an intracellular domain. When MOG was displayed on transfected cells, patients with MOG-Abs recognized full-length MOG much better than its N-terminal part with the first hydrophobic domain (p < 0.0001). Even antibodies affinity-purified with the extracellular part of MOG recognized full-length MOG better than the extracellular part of MOG after transfection. The second hydrophobic domain of MOG enhanced the recognition of the extracellular part of MOG by antibodies from patients as seen with truncated variants of MOG. We confirmed the pivotal role of the second hydrophobic domain by fusing the intracellular part of MOG from the evolutionary distant opossum to the human extracellular part; the chimeric construct restored the antibody-binding completely. Further, we found that in contrast to 8-18C5, MOG-Abs from patients bound preferentially as F(ab')2 rather than Fab. It was previously found that bivalent binding of human IgG1, the prominent isotype of MOG-Abs, requires that its target antigen is displayed at a distance of 13-16 nm. We found that, upon transfection, molecules of MOG did not interact so closely to induce a Förster resonance energy transfer (FRET) signal, indicating that they are more than 6 nm apart. We propose that the intracellular part of MOG holds the monomers apart at a suitable distance for bivalent binding; this could explain why a cell-based assay is needed to identify MOG-Abs. Our finding that MOG-Abs from most patients require bivalent binding has implications for understanding the pathogenesis of MOG-antibody-associated-disorders. Since bivalently bound antibodies have been reported to only poorly bind C1q, we speculate that the pathogenicity of MOG-Abs is mostly mediated by other mechanisms than complement activation. Therefore, therapeutic inhibition of complement activation should be less efficient in MOG-Ab associated disorders than in patients with Abs to aquaporin-4.