Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disorders: Toward a New Spectrum of Inflammatory Demyelinating CNS Disorders?

Molecular dynamics simulation of the brain-isolated single-domain antibody/nanobody from camels through in vivo phage display screening

Introduction

During the last decade, there has been a significant rise in the use of therapeutic antibodies or passive immunotherapy for treating various conditions like inflammation and cancer. However, these proteins face challenges reaching the brain and often require specialized delivery methods such as single-domain antibodies (sdAbs). Traditional antibodies struggle to efficiently cross the blood-brain barrier (BBB), hindering their effectiveness. Receptor-mediated transcytosis (RMT) offers a promising pathway for transporting large molecules essential for brain function and treatment across the BBB.

Methods

SdAbs and peptide ligands with an affinity for RMT receptors are commonly employed to enhance the transport of biotherapeutics compounds across the BBB. This research used a sdAbs phage-displayed library from 13 camelus dromedarius samples to identify sdABs that specifically bind to and are internalized by human BBB endothelial cells (ECs) through in vivo panning.

Results and discussion

One sdAb, defined as FB24, was isolated, sequenced, translated into an open reading frame (ORF), and subjected to three-dimensional (3D) modeling. Molecular docking and molecular dynamics simulations were carried out by the HADDOCK web server and GROMACS, respectively, to evaluate the interaction between FB24 and EC receptors in silico. The docking results revealed that FB24 exhibited binding activity against potential EC receptors with -1.7 to -2.7 ranged z score and maintained a stable structure. The docked complex of FB24-RAGE (receptor for advanced glycation end products, also known as advanced glycation end product receptor [AGER]) showed 18 hydrogen bonds and 213 non-bonded contacts. It was chosen for further analysis by molecular dynamics simulations by GROMACS. This complex showed a stable condition, and its root mean square deviation (RMSD) was 0.218 nm. The results suggest that FB24 could serve as a suitable carrier vector for transporting therapeutic and diagnostic agents across the BBB to the brain through a non-invasive route.

Clinical and radiographic features of a cohort of adult and pediatric subjects in the Pacific Northwest with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD)

BACKGROUND

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a newly described clinical entity comprised of isolated or recurrent attacks of optic neuritis, transverse myelitis, acute disseminated encephalomyelitis (ADEM), encephalitis, or seronegative NMOSD. Prior studies report that 30-80 % of children and adults with MOGAD go on to have relapses though there are no reliable predictors. The objectives of this study were to (1) describe the demographic, clinical, and radiographic patterns of MOGAD at our center and (2) identify possible predictors of relapsing disease.

METHODS

Single-center retrospective cohort study of pediatric and adult subjects with MOGAD evaluated at least once at our center between January 1, 2017 and September 30, 2022. Eligible subjects had a history of positive MOG-IgG and consistent clinical syndrome comprised of an initial attack of optic neuritis (ON), transverse myelitis (TM), ADEM, cerebral cortical encephalitis, seronegative neuromyelitis optica (simultaneous ON and TM), isolated brainstem or cerebellar syndrome, or other (not fitting into another group). Relapsing subjects or those remaining monophasic at 12 months were included in the analyses of predictors of relapsing disease. Covariates included age, sex, race/ethnicity, and index event phenotype. Unadjusted and adjusted risk ratios were calculated for pediatric and adult subjects.

RESULTS

We describe the demographic, clinical, and radiographic characteristics of 58 subjects with MOGAD. Covariates from 48 subjects were analyzed for predictors of relapsing disease. In adults, Hispanics and non-White non-Hispanics were at increased risk of relapsing disease compared to non-Hispanic Whites [Adjusted RR 1.52 (95 % CI: 1.01, 2.30)]. There were no significant associations in the pediatric group.

CONCLUSION

This study is the first to describe a cohort of MOGAD in the Pacific Northwest. Our findings highlight racial and ethnic differences in risk of relapsing MOGAD in adults. Further studies on racial and ethnic differences in MOGAD are needed to confirm these findings.

Case of MOG-IgG-associated disease with ankylosing spondylitis: A rare coexistence

Myelin oligodendrocyte glycoprotein-associated disease (MOGAD) is an inflammatory neurological disease. It progresses with attacks by affecting the optic nerves and spinal cord. Bilateral or recurrent optic neuritis are the most common findings in adult patients. Its association with systemic autoimmune disorders such as Sjögren syndrome, antiphospholipid syndrome, autoimmune thyroiditis, and celiac disease is rare. The first and only case of MOGAD in a patient with ankylosing spondylitis with a history of anti-tumor necrosis factor-alpha (anti-TNF-α) use was reported. Herein, we present the coexistence of MOGAD in a patient with AS who did not have a history of anti-TNF-α therapy.

High level of agreement in a fixed vs. live cell-based assay for antibodies to myelin oligodendrocyte glycoprotein in a real-world clinical laboratory setting

Introduction

As recognition of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease becomes more widespread, the importance of appropriately ordering and interpreting diagnostic testing for this antibody increases. Several assays are commercially available for MOG testing, and based on a few small studies with very few discrepant results, some have suggested that live cell-based assays (CBA) are superior to fixed CBA for clinical MOG antibody testing. We aimed to determine the real-world agreement between a fixed and live CBA for MOG using two of the most commonly available commercial testing platforms.

Methods

We compared paired clinical samples tested at two national clinical reference laboratories and determined the real-world agreement between the fixed CBA and live CBA.

Results

Of 322 paired samples tested on both platforms, 53 were positive and 246 were negative by both methodologies (agreement 92.9%, Cohen's kappa 0.78, [0.69-0.86]). Spearman correlation coefficient was 0.80 (p < 0.0001). Of the discrepant results, only 1 of 14 results positive by the live CBA had a titer greater than 1:100, and only 1 of 9 results positive by the fixed CBA had a titer of greater than 1:80. Lower titers on the fixed CBA correlate to higher titers on the live CBA.

Conclusion

Overall, there is excellent agreement between fixed and live CBA for MOG antibody testing in a real-world clinical laboratory setting. Clinicians should be aware of which method they use to assess any given patient, as titers are comparable, but not identical between the assays.

Long-lasting pain and somatosensory disturbances in children with myelin oligodendrocyte glycoprotein antibody-associated disease

Myelin oligodendrocyte glycoprotein antibody (MOG-Ab) is an autoantibody associated with acquired demyelinating syndrome (ADS) in childhood and adults. The pathogenic roles of MOG-Ab and long-term outcomes of children with MOG-Ab-associated disease (MOGAD) remain elusive. We investigated the clinical features of children with ADS during follow-up in our institute. Clinical data were retrospectively analyzed using medical charts of patients managed in Kyushu University Hospital from January 1st, 2001, to March 31st, 2022. Participants were children of < 18 years of age when they received a diagnosis of ADS in our hospital. Cell-based assays were used to detect MOG-Ab in serum or cerebrospinal fluid at the onset or recurrence of ADS. The clinical and neuroimaging data of MOG-Ab-positive and MOG-Ab-negative patients were statistically analyzed. Among 31 patients enrolled in this study, 22 (13 females, 59%) received tests for MOG antibodies. Thirteen cases (59%) were MOG-Ab-positive and were therefore defined as MOGAD; 9 (41%) were MOG-Ab-negative. There were no differences between MOGAD and MOG-Ab-negative patients in age at onset, sex, diagnostic subcategories, or duration of follow-up. MOGAD patients experienced headache and/or somatosensory symptoms more frequently than MOG-Ab-negative patients (12/13 (92%) vs. 3/9 (22%); p = 0.0066). Somatosensory problems included persistent pain with hyperesthesia in the left toe, perineal dysesthesia, and facial hypesthesia. No specific neuroimaging findings were associated with MOGAD or the presence of somatosensory symptoms.

CONCLUSIONS

Long-lasting somatosensory disturbances are prominent comorbidities in children with MOGAD. Prospective cohorts are required to identify molecular and immunogenetic profiles associated with somatosensory problems in MOGAD.

WHAT IS KNOWN

• Recurrence of demyelinating events occurs in a group of children with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

WHAT IS NEW

• Long-lasting headache and somatosensory problems are frequent comorbidities with pediatric MOGAD. Pain and somatosensory problems may persist for more than 5 years. • Neuroimaging data do not indicate specific findings in children with somatic disturbances.

Pathophysiology of myelin oligodendrocyte glycoprotein antibody disease

Myelin Oligodendrocyte Glycoprotein Antibody Disease (MOGAD) is a spectrum of diseases, including optic neuritis, transverse myelitis, acute disseminated encephalomyelitis, and cerebral cortical encephalitis. In addition to distinct clinical, radiological, and immunological features, the infectious prodrome is more commonly reported in MOGAD (37-70%) than NMOSD (15-35%). Interestingly, pediatric MOGAD is not more aggressive than adult-onset MOGAD, unlike in multiple sclerosis (MS), where annualized relapse rates are three times higher in pediatric-onset MS. MOGAD pathophysiology is driven by acute attacks during which T cells and MOG antibodies cross blood brain barrier (BBB). MOGAD lesions show a perivenous confluent pattern around the small veins, lacking the radiological central vein sign. Initial activation of T cells in the periphery is followed by reactivation in the subarachnoid/perivascular spaces by MOG-laden antigen-presenting cells and inflammatory CSF milieu, which enables T cells to infiltrate CNS parenchyma. CD4+ T cells, unlike CD8+ T cells in MS, are the dominant T cell type found in lesion histology. Granulocytes, macrophages/microglia, and activated complement are also found in the lesions, which could contribute to demyelination during acute relapses. MOG antibodies potentially contribute to pathology by opsonizing MOG, complement activation, and antibody-dependent cellular cytotoxicity. Stimulation of peripheral MOG-specific B cells through TLR stimulation or T follicular helper cells might help differentiate MOG antibody-producing plasma cells in the peripheral blood. Neuroinflammatory biomarkers (such as MBP, sNFL, GFAP, Tau) in MOGAD support that most axonal damage happens in the initial attack, whereas relapses are associated with increased myelin damage.

Non-infectious meningitis and CNS demyelinating diseases: A conceptual review

Many cases of aseptic meningitis or meningoencephalitis, unresponsive to antimicrobial treatments, have been reported recently in patients with established/new-onset central nervous system (CNS) inflammatory demyelinating diseases (CNSIDDs). Given the higher probability of infectious etiologies, CNSIDDs are rarely considered among the differentials in meningitis or meningoencephalitis cases. We gathered and tabulated cases of non-infectious, steroid-responsive meningitis or meningoencephalitis associated with neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein-associated disease (MOGAD). This conceptual review highlights the need to bolster routine infectious workups with immunological workups in cases of meningoencephalitis or meningitis where potential autoimmune etiologies can be suspected. Although differentiating CNSIDDs with meningeal involvement from infectious meningitis may not substantially affect acute treatment strategies, long-term management and follow-up of the two are entirely different. We also discuss future research directions and hypotheses on how CNSIDDs may be associated with meningitis-like presentations, e.g. overlapping glial fibrillary acidic protein astrocytopathy or autoimmune encephalitis, alterations in regulatory T-helper cells function, and undetected viral agents.

Clinical characteristics of myelin-oligodendrocyte glycoprotein antibody-positive pediatric autoimmune encephalitis without demyelination: A case series

Purpose

To facilitate the identification of myelin-oligodendrocyte glycoprotein (MOG) antibody-associated diseases in pediatric autoimmune encephalitis without demyelination, we explored the clinical characteristics of patients having MOG antibody-positive pediatric autoimmune encephalitis without demyelination in Children's Hospital of Chongqing Medical University, China.

Methods

We reviewed patients' medical records from January 2019 to June 2022 and retrospectively analyzed clinical manifestations, brain magnetic resonance imaging (MRI) findings, laboratory findings, treatments and outcomes of children with autoimmune encephalitis who tested positive for MOG antibodies in serum but for whom demyelination was not detected on MRI.

Results

Eighteen patients (6 boys, 12 girls; median age: 103.2 (range: 36-160) months) were included: 15 tested positive for MOG antibodies in both serum and cerebrospinal fluid (CSF); three tested positive only in serum. The most common clinical symptoms were altered mental status (18/18), fever (16/18), headache (14/18), seizures (6/18) and focal neurologic deficits (5/18). All patients had CSF pleocytosis (median count: 74/µL, range: 14-380/µL); five patients had elevated CSF protein levels (median: 0.85 g/L, range: 0.53-1.48 g/L) simultaneously. CSF glucose levels were normal in all patients. Abnormal electroencephalogram (EEG) results were found in 12 patients: generalized or focal slowing (9/12), focal epileptic discharges (2/12), and generalized slowing and focal epileptic discharges (1/12). Twelve of the 18 patients showed hyperintense T2-weighted lesions on brain MRI in the cortex (6), basal ganglia (5), thalamus (3), cerebellum (4), and brainstem (2). All patients received immunotherapy and had favorable outcomes at discharge (modified Rankin scale score: <2). Three children relapsed once; however, all children had good outcomes at the last follow-up.

Conclusion

MOG antibody-positive pediatric autoimmune encephalitis without demyelination is mainly characterized by prolonged fever, altered mental status, headache, mild-to-moderate increase in cell count in the CSF, and normal or abnormal brain MRI, which may involve any part outside the white matter without specificity. All patients with MOG antibody-positive pediatric autoimmune encephalitis without demyelination had favorable outcomes after immunotherapy, while a few patients relapsed once.

Myelin Oligodendrocyte Glycoprotein-Associated Disorders

PURPOSE OF REVIEW

Anti-myelin oligodendrocyte glycoprotein (MOG) autoantibodies have become a recognized cause of a pathophysiologically distinct group of central nervous system (CNS) autoimmune diseases. MOG-associated disorders can easily be confused with other CNS diseases such as multiple sclerosis or neuromyelitis optica, but they have a distinct clinical phenotype and prognosis.

RECENT FINDINGS

Most patients with MOG-associated disorders exhibit optic neuritis, myelitis, or acute disseminated encephalomyelitis (ADEM) alone, sequentially, or in combination; the disease may be either monophasic or relapsing. Recent case reports have continued to expand the clinical spectrum of disease, and increasingly larger cohort studies have helped clarify its pathophysiology and natural history.

SUMMARY

Anti-MOG-associated disorders comprise a substantial subset of patients previously thought to have other seronegative CNS diseases. Accurate diagnosis is important because the relapse patterns and prognosis for MOG-associated disorders are unique. Immunotherapy appears to successfully mitigate the disease, although not all agents are equally effective. The emerging large-scale data describing the clinical spectrum and natural history of MOG-associated disorders will be foundational for future therapeutic trials.

Clinical and diagnostic spectrum of optic neuritis: A single-center retrospective study of disorders associated with multiple sclerosis, anti-aquaporin-4 and anti-myelin oligodendrocyte glycoprotein antibodies

OBJECTIVE

Optic neuritis (ON) is an immune-mediated optic neuropathy associated with multiple immune-mediated neurological conditions. Our aim was to characterize the clinical and diagnostic features of first or initial episodes of ON associated with multiple sclerosis (MS)-associated (typical) and antibody-related (atypical) ON.

METHODS

Retrospective, single institution, medical record review. We analyzed demographic, clinical, laboratory, and radiographic findings of 139 patients who presented with first episodes of MS-associated ON (MS-ON), aquaporin 4 antibody-associated ON (AQP4-ON), and myelin oligodendrocyte glycoprotein antibody-associated ON (MOG-ON) between January 2015 and October 2019 without preceding diagnosis. Simple hypothesis testing assessed differences between groups were performed.

RESULTS

Of 139 patients (109 [79 %] women; 29 [21 %] men; mean age 47 [SD, 14] years), 106 had MS-ON, 25 had AQP4-ON, and 8 had MOG-ON. Patients with MOG-ON had the highest recurrence rate (88 %) relative to MS-ON (28 %) and AQP4-ON (56 %) patients (P < .001). Patients with AQP4-ON had the highest mean visual functional system scores (4.3 [SD, 1.8]) relative to MS-ON (2.0 [SD, 1.9]) and MOG-ON patients (2.8 [SD, 2.0]) (P < .001).

CONCLUSION

Patients presenting with initial episodes of ON exhibit a range radiographic and laboratory feature depending on the underlying associated disease. Understanding the variable characteristics of typical (MS-associated) and atypical (antibody-associated) ON may help physicians accurately diagnose and effectively treat ON.

Children suspected of having intracranial infection with normal brain magnetic resonance imaging may be associated with the myelin oligodendrocyte glycoprotein antibody

PURPOSE

To confirm whether encephalitis due to unknown causes but with normal brain magnetic resonance imaging (MRI) may be associated with the myelin oligodendrocyte glycoprotein (MOG) antibody.

METHODS

We retrospectively analyzed and summarized the characteristics of three patients initially suspected of having intracranial infections with normal brain MRI, and ultimately tested positive for anti-MOG antibody.

RESULTS

The three patients mainly presented with long-term fever accompanied by headaches and drowsiness. Auxiliary examinations showed obvious leukocytosis in peripheral blood and leukocytosis and increased protein expression in cerebrospinal fluid (CSF); furthermore, brain MRI was normal. These findings suggested intracranial infection, especially bacterial meningitis. No patient showed a response to prolonged anti-bacterial therapy; however, they recovered with glucocorticoid therapy, which was prescribed after anti-MOG antibodies were detected in the serum and CSF samples.

CONCLUSION

Anti-MOG antibody detection should be performed early for patients with suspected encephalitis due to unknown causes with normal brain MRI, to identify whether they have MOG antibody-associated diseases (MOGAD).

Optomyelitis associated with the presence of antibodies to myelin oligodendrocyte glycoprotein. Case report

Antibodies to myelin-oligodendrocyte glycoprotein (anti-MOG-IgG) is a specific biomarker that has been detected in peripheral blood from children with acute multiple encephalomyelitis (ADEM) as well as in adults with aquaporin-4 (AQP4), associated with seronegative opticoneuromyelitis spectrum disease (NMOSD), brainstem encephalitis, longitudinally disseminated transverse myelitis, and optic neuritis. Most experts now consider MOG-IgG-associated disorder (MOG-AD) an independent disease immunopathogenetically distinct from classical multiple sclerosis (MS) and aquaporin-4 (AQP4)-IgG-positive optomyelitis. Isolated, bilateral, and less frequently unilateral OH, with simultaneous or sequential involvement of the eyes, is the most frequent clinical manifestation of MOG-AD. Because of the significant overlap in the clinical and radiological picture, MOG-AD is often misdiagnosed as MS. Timely diagnosis is critical to ensure appropriate treatment. This article describes a clinical case of anti-MOG-IgG encephalomyelitis with late-onset ON initially diagnosed as MS.

Dysregulated B cell differentiation towards antibody-secreting cells in neuromyelitis optica spectrum disorder

Background

Anti-aquaporin 4 (AQP4) antibody (AQP4-Ab) is involved in the pathogenesis of neuromyelitis optica spectrum disorder (NMOSD). However, the mechanism involved in AQP4-Ab production remains unclear.

Methods

We analyzed the immunophenotypes of patients with NMOSD and other neuroinflammatory diseases as well as healthy controls (HC) using flow cytometry. Transcriptome analysis of B cell subsets obtained from NMOSD patients and HCs was performed. The differentiation capacity of B cell subsets into antibody-secreting cells was analyzed.

Results

The frequencies of switched memory B (SMB) cells and plasmablasts were increased and that of naïve B cells was decreased in NMOSD patients compared with relapsing–remitting multiple sclerosis patients and HC. SMB cells from NMOSD patients had an enhanced potential to differentiate into antibody-secreting cells when cocultured with T peripheral helper cells. Transcriptome analysis revealed that the profiles of B cell lineage transcription factors in NMOSD were skewed towards antibody-secreting cells and that IL-2 signaling was upregulated, particularly in naïve B cells. Naïve B cells expressing CD25, a receptor of IL-2, were increased in NMOSD patients and had a higher potential to differentiate into antibody-secreting cells, suggesting CD25⁺ naïve B cells are committed to differentiate into antibody-secreting cells.

Conclusions

To the best of our knowledge, this is the first study to demonstrate that B cells in NMOSD patients are abnormally skewed towards antibody-secreting cells at the transcriptome level during the early differentiation phase, and that IL-2 might participate in this pathogenic process. Our study indicates that CD25⁺ naïve B cells are a novel candidate precursor of antibody-secreting cells in autoimmune diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02375-w.

Central Nervous System Delivery of Antibodies and Their Single-Domain Antibodies and Variable Fragment Derivatives with Focus on Intranasal Nose to Brain Administration

IgG antibodies are some of the most important biopharmaceutical molecules with a high market volume. In spite of the fact that clinical therapies with antibodies are broadly utilized in oncology, immunology and hematology, their delivery strategies and biodistribution need improvement, their limitations being due to their size and poor ability to penetrate into tissues. In view of their small size, there is a rising interest in derivatives, such as single-domain antibodies and single-chain variable fragments, for clinical diagnostic but also therapeutic applications. Smaller antibody formats combine several benefits for clinical applications and can be manufactured at reduced production costs compared with full-length IgGs. Moreover, such formats have a relevant potential for targeted drug delivery that directs drug cargo to a specific tissue or across the blood–brain barrier. In this review, we give an overview of the challenges for antibody drug delivery in general and focus on intranasal delivery to the central nervous system with antibody formats of different sizes.

Relapse activity in the chronic phase of anti-myelin-oligodendrocyte glycoprotein antibody-associated disease

Objective

The patterns of relapse and relapse-prevention strategies for anti-myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are not completely investigated. We compared the patterns of relapse in later stages of MOGAD with those of anti-aquaporin-4 antibody (AQP4-Ab)-positive neuromyelitis optica spectrum disorder (NMOSD).

Methods

In this observational, comparative cohort study, 66 patients with MOGAD and 90 with AQP4-Ab-positive NMOSD were enrolled. We compared the patterns of relapse and annualized relapse rates (ARRs) in the first 10 years from disease onset, stratified by relapse-prevention treatments.

Results

Approximately 50% of the patients with MOGAD experienced relapses in the first 10 years. Among those not undergoing relapse-prevention treatments, ARRs in the first 5 years were slightly lower in MOGAD patients than in AQP4-Ab-positive NMOSD patients (MOGAD vs. AQP4-Ab NMOSD: 0.19 vs. 0.30; p = 0.0753). After 5 years, the ARR decreased in MOGAD patients (MOGAD vs. AQP4-Ab NMOSD: 0.05 vs. 0.34; p = 0.0001), with a 72% reduction from the first 5 years (p = 0.0090). Eight (61.5%) of the 13 MOGAD patients with more than 10-year follow-up from disease onset showed relapse 10 years after onset. Clustering in the timing and phenotype of attacks was observed in both disease patients. The effectiveness of long-term low-dose oral PSL for relapse prevention in patients with MOGAD has not been determined.

Conclusions

The relapse risk in patients with MOGAD is generally lower than that in patients with AQP4-Ab-positive NMOSD, especially 5 years after onset. Meanwhile, relapses later than 10 years from onset are not rare in both diseases.

Evidence for and against subclinical disease activity and progressive disease in MOG antibody disease and neuromyelitis optica spectrum disorder

Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) and aquaporin-4 IgG seropositive neuromyelitis optica spectrum disorder (AQP4-IgG+ NMOSD) are generally considered to be relapsing disorders, without clinical progression or subclinical disease activity outside of clinical relapses, in contrast to multiple sclerosis (MS). With advances in the diagnosis and treatment of these conditions, prolonged periods of remission without relapses can be achieved, and the question of whether progressive disease courses can occur has re-emerged. In this review, we focus on studies exploring evidence for and against relapse-independent clinical progression and/or subclinical disease activity in patients with MOGAD and AQP4-IgG+ NMOSD.

Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease and Varicella Zoster Virus Infection - Frequency of an Association

To determine whether there is a correlation between myelin oligodendrocyte glycoprotein (MOG) antibody-associated diseases and varicella zoster virus (VZV) infection. We provide a case report and performed a study to determine the frequency of MOG antibodies (MOG-IgG) in neurological VZV infections. Patients admitted to the Medical University of Innsbruck from 2008-2020 with a diagnosis of a neurological manifestation of VZV infection (n=59) were included in this study; patients with neuroborreliosis (n=34) served as control group. MOG-IgG was detected using live cell-based assays. In addition, we performed a literature review focusing on MOG and aquaporin-4 (AQP4) antibodies and their association with VZV infection. Our case presented with VZV-associated longitudinally extensive transverse myelitis and had MOG-IgG at a titer of 1:1280. In the study, we did not detect MOG-IgG in any other patient neither in the VZV group (including 15 with VZV encephalitis/myelitis) nor in the neuroborreliosis group. In the review of the literature, 3 cases with MOG-IgG and additional 9 cases with AQP4 IgG associated disorders in association with a VZV infection were identified. MOG-IgG are rarely detected in patients with VZV infections associated with neurological diseases.

Approach to optic neuritis: An update

Over the past few years, there has been remarkable development in the area of optic neuritis. The discovery of new antibodies has improved our understanding of the pathology of the disease. Antiaquaporin4 antibodies and antimyelin oligodendrocytes antibodies are now considered as distinct entities of optic neuritis with their specific clinical presentation, neuroimaging characteristics, treatment options, and course of the disease. Similarly, there has been a substantial change in the treatment of optic neuritis which was earlier limited to steroids and interferons. The development of new immunosuppressant drugs and monoclonal antibodies has reduced the relapses and improved the prognosis of optic neuritis as well as an associated systemic disease. This review article tends to provide an update on the approach and management of optic neuritis.

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.

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.

Myelin oligodendrocyte glycoprotein antibody-associated disorders: clinical spectrum, diagnostic evaluation, and treatment options

Inflammatory or immune-mediated demyelinating central nervous system (CNS) syndromes include a broad spectrum of clinical phenotype and different overlapping diseases. Antibodies against myelin oligodendrocyte glycoprotein (MOG-Ab) have been found in some cases of these demyelinating diseases, particularly in children. MOG-Ab is associated with a wider clinical phenotype not limited to neuromyelitis optica spectrum disorder, with most patients presenting with optic neuritis, acute disseminated encephalomyelitis (ADEM) or ADEM-like encephalitis with brain demyelinating lesions, and/or myelitis. Using specific cell-based assays, MOG-Ab is becoming a potential biomarker of inflammatory demyelinating disorders of the CNS. A humoral immune reaction against MOG was recently found in monophasic diseases and recurrent/multiphasic clinical progression, particularly in pediatric patients. This review summarizes the data regarding MOG-Ab as an impending biological marker for discriminating between these diverse demyelinating CNS diseases and discusses recent developments, clinical applications, and findings regarding the immunopathogenesis of MOG-Ab-associated disorders.

Novel insights into pathophysiology and therapeutic possibilities reveal further differences between AQP4-IgG- and MOG-IgG-associated diseases

PURPOSE OF REVIEW

This review summarizes recent insights into the pathogenesis and therapeutic options for patients with MOG- or AQP4-antibodies.

RECENT FINDINGS

Although AQP4-IgG are linked to NMOSD, MOG-IgG-associated diseases (MOGAD) include a broader clinical spectrum of autoimmune diseases of the central nervous system (CNS). Details of membrane assembly of AQP4-IgG required for complement activation have been uncovered. Affinity-purified MOG-IgG from patients were shown to be pathogenic by induction of demyelination when the blood--brain barrier (BBB) was breached and by enhancement of activation of cognate T cells. A high-affinity AQP4-IgG, given peripherally, could induce NMOSD-like lesions in rats in the absence of BBB breach. Circulating AQP4-specific and MOG-specific B cells were identified and suggest differences in origin of MOG-antibodies or AQP4-antibodies. Patients with MOG-IgG show a dichotomy concerning circulating MOG-specific B cells; whether this is related to differences in clinical response of anti-CD20 therapy remains to be analyzed. Clinical trials of AQP4-IgG-positive NMOSD patients showed success with eculizumab (preventing cleavage of complement factor C5, thereby blocking formation of chemotactic C5a and membrane attack complex C9neo), inebilizumab (depleting CD19 + B cells), and satralizumab (anti-IL-6R blocking IL-6 actions).

SUMMARY

New insights into pathological mechanisms and therapeutic responses argue to consider NMOSD with AQP4-IgG and MOGAD as separate disease entities.

Progression pattern of neurological disability with respect to clinical attacks in anti-MOG antibody-associated disorders

The progression pattern of neurological disability among patients with anti-myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGAD) was evaluated. Neurological disability was evaluated annually for 408 person-years in 50 patients. More than 30% of the patients had clinical relapses in the first 5 years. Disability progression independent of relapse activity (PIRA) was not seen, whereas a stepwise disability progression was observed after clinical attacks in some instances. Disability worsening was more frequent after relapses than after the onset episode (p < 0.01). Similar to patients with anti-aquaporin-4 antibodies, attack-related stepwise disability progression without PIRA is typical in MOGAD, suggesting the importance of relapse prevention.

Neuromyelitis optica spectrum disorders

The disease concept of Neuromyelitis Optica Spectrum Disorders(NMOSD) has undergone a significant change over the last two decades including the detection of Myelin Oligodendrocyte Glycoprotein(MOG) antibody in patients who are seronegative for aquaporin-4 antibody. Aquaporin-4 antibody positive NMOSD is now regarded as an immune astrocytopathy. Conversely, MOG antibody associated disease is known to target myelin rather than astrocytes, leading to an NMOSD syndrome with distinct clinical and radiological features. Incorporation of clinical features like area postrema syndrome, brainstem syndrome, diencephalic syndrome and cortical manifestations as core clinical characteristics into the revised diagnostic criteria has widened the clinical spectrum of NMOSD. With the development of these criteria, it is possible to make the diagnosis at an earlier stage so that effective immunosuppression can be instituted promptly for a better long-term prognosis. Newer therapeutic agents have been introduced for aquaporin-4 seropositive NMOSD disease; however, challenges remain in treating seronegative disease because of limited treatment options.

Understanding Pediatric Neuroimmune Disorder Conflicts: A Neuroradiologic Approach in the Molecular Era

Neuroimmune disorders in children are a complex group of inflammatory conditions of the central nervous system with diverse pathophysiologic mechanisms and clinical manifestations. Improvements in antibody analysis, genetics, neuroradiology, and different clinical phenotyping have expanded knowledge of the different neuroimmune disorders. The authors focus on pediatric-onset myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease, which is a new entity in the spectrum of inflammatory demyelinating diseases, distinct from both multiple sclerosis (MS) and anti-aquaporin-4 (AQP4) antibody neuromyelitis optica spectrum disorders (NMOSDs). The authors review the importance of an optimized antibody-detection assay, the frequency of MOG antibodies in children with acquired demyelinating syndrome (ADS), the disease course, the clinical spectrum, proposed diagnostic criteria, and neuroimaging of MOG antibody-associated disease. Also, they outline differential diagnosis from other neuroimmune disorders in children according to the putative primary immune mechanism. Finally, they recommend a diagnostic algorithm for the first manifestation of ADS or relapsing ADS that leads to four demyelinating syndromes: MOG antibody-associated disease, AQP4 antibody NMOSDs, MS, and seronegative relapsing ADS. This diagnostic approach provides a framework for the strategic role of neuroradiology in diagnosis of ADS and decision making, to optimize patient care and treatment outcome in concert with clinicians. Online supplemental material is available for this article. ^©RSNA, 2020.

[Myelin oligodendrocyte glycoprotein immunoglobulin G-associated encephalomyelitis]

The article discusses the role of myelin oligodendrocyte glycoprotein immunoglobulin G (MOG-IgG) in demyelinating diseases of the central nervous system. Clinical phenotypes of demyelinating syndromes associated with MOG-IgG that are currently included into neuromyelitis optica spectrum disorders (NMOSD) are described. However, it has been shown that encephalomyelitis associated with MOG-IgG (MOG-EM) has certain clinical, radiological, immunological and histopathological features that make it possible to single out these syndromes into a separate nosological form. We provide International recommendations that establish indications for testing MOG-IgG using cell-based assay. We discuss epidemiological issues and classification challenges of the disease. Various approaches to treatment and prevention of relapses of MOG-EM are analyzed.

Autoimmune and demyelinating optic neuritis

The knowledge on demyelinating and autoimmune optic neuropathies has experienced a revolution the last decade since the discovery of anti-aquaporin 4 antibody. Improvements in diagnostic techniques, and the finding of new targets, along with advances in neuro-immunology have led to the detection of antibodies related to demyelinating diseases. A review is presented on the classical and new concepts in optic neuritis. The debate on the classification of demyelinating and autoimmune optic neuritis is presented. Furthermore, the updated diagnostic criteria in multiple sclerosis and neuro-myelitis optics are described. Finally, the latest insights into Myelin Oligodendrocyte Glycoprotein (MOG) disorders and chronic-recurring optic neuropathies (CRION) are highlited.

Cerebrospinal Fluid Testing for Multiple Sclerosis

Multiple sclerosis is one of the most common autoimmune diseases affecting the central nervous system. Current guidelines characterize multiple sclerosis and related conditions based on clinical, imaging, and body fluid markers. In this review, we describe how laboratory analysis of cerebrospinal fluid is currently performed and discuss new approaches under development for multiple sclerosis diagnostics.

Epidemiology of Pediatric NMOSD in Germany and Austria

Background: Neuromyelitis optica spectrum disorders (NMOSD) are severe inflammatory demyelinating disorders of the central nervous system mainly characterized by recurrent episodes of uni- or bilateral optic neuritis (ON), transverse myelitis (TM) and brainstem syndromes (BS). The majority of adult patients has serum antibodies directed against the water channel protein aquaporin 4 (AQP4-abs). In pediatric patients, AQP4-abs are less, while antibodies against myelin oligodendrocyte glycoprotein (MOG-abs) are more frequently detectable than in adults. Some children with NMOSD have neither AQP4- nor MOG-ab (double-seronegative).

Objective: Evaluation of epidemiological data regarding incidence and prevalence of pediatric NMOSD in Germany and Austria.

Methods: We recruited pediatric NMOSD patients between 1 March 2017 and 28 February 2019 with five different tools: (1) ESPED (Surveillance Unit for Rare Pediatric Disorders in Germany), (2) ESNEK (Surveillance for Rare Neurological Disorders during Childhood), (3) pediatric neurology working group within the Austrian Society of Pediatrics and Adolescent Medicine, (4) BIOMARKER Study and (5) NEMOS (Neuromyelitis optica Study Group). We requested data regarding clinical symptoms, antibody status, therapy regimen and response via a standardized questionnaire.

Results: During the 2-year recruitment period, 46 (both incidental and prevalent) patients with a suspected diagnosis of NMOSD were brought to our attention. Twenty-two of these patients did not fulfill the inclusion criteria. Of the remaining 24 children, 22 had a median age at onset of 11 (range 3–17) years and 16/22 were female (72.7%) (no data in two patients). Sixteen of 24 patients were AQP4-ab positive (67%), 4/24 MOG-ab positive (16.7%), three children were double-seronegative and in one patient no antibody testing was done. We calculated an incidence rate of 0.022 per 100,000 person-years for Germany, while there was no incidental case in Austria during the recruitment period. The prevalence rate was 0.147 and 0.267 per 100,000 persons in Germany and Austria, respectively.

Conclusion: Pediatric NMOSD, with and without associated antibodies, are very rare even considering the different limitations of our study. An unexpected finding was that a considerable proportion of patients was tested neither for AQP4- nor MOG-abs during diagnostic work-up, which should prompt to establish and disseminate appropriate guidelines.

The pathology of central nervous system inflammatory demyelinating disease accompanying myelin oligodendrocyte glycoprotein autoantibody

We sought to define the pathological features of myelin oligodendrocyte glycoprotein (MOG) antibody associated disorders (MOGAD) in an archival autopsy/biopsy cohort. We histopathologically analyzed 2 autopsies and 22 brain biopsies from patients with CNS inflammatory demyelinating diseases seropositive for MOG-antibody by live-cell-based-assay with full length MOG in its conformational form. MOGAD autopsies (ages 52 and 67) demonstrate the full spectrum of histopathological features observed within the 22 brain biopsies (median age, 10 years; range, 1–66; 56% female). Clinical, radiologic, and laboratory characteristics and course (78% relapsing) are consistent with MOGAD. MOGAD pathology is dominated by coexistence of both perivenous and confluent white matter demyelination, with an over-representation of intracortical demyelinated lesions compared to typical MS. Radially expanding confluent slowly expanding smoldering lesions in the white matter as seen in MS, are not present. A CD4+ T-cell dominated inflammatory reaction with granulocytic infiltration predominates. Complement deposition is present in all active white matter lesions, but a preferential loss of MOG is not observed. AQP4 is preserved, with absence of dystrophic astrocytes, and variable oligodendrocyte and axonal destruction. MOGAD is pathologically distinguished from AQP4-IgG seropositive NMOSD, but shares some overlapping features with both MS and ADEM, suggesting a transitional pathology. Complement deposition in the absence of selective MOG protein loss suggest humoral mechanisms are involved, however argue against endocytic internalization of the MOG antigen. Parallels with MOG-EAE suggest MOG may be an amplification factor that augments CNS demyelination, possibly via complement mediated destruction of myelin or ADCC phagocytosis.

Case Series: Myelin Oligodendrocyte Glycoprotein-Immunoglobulin G-Related Disease Spectrum

Introduction: Myelin oligodendrocyte glycoprotein-immunoglobulin G (MOG-IgG)-related disease was initially described as a subtype of neuromyelitis optica spectrum disorder (NMOSD) with antibodies against MOG. However, it has recently been described as a separate disease entity with clinical and radiological features that overlap those of multiple sclerosis (MS) and NMOSD; the clinical features of this disease phenotype remain undetermined. We herein report the clinical presentation of nine MOG-IgG-positive patients, not all of whom fulfill the NMOSD criteria, in order to highlight the features and challenges of this condition.

Method: We retrospectively reviewed the records of the London (Ontario) MS clinic to identify patients diagnosed with positive MOG antibodies based on the 2015 NMOSD consensus criteria.

Result: Nine patients were identified, all Caucasian. Seven (78%) were female, and the median age of onset was 41 years (range, 28–69 years); the median Expanded Disability Status Scale score at onset was 3.0 (range, 2.0–4.0). A monophasic course was noted in two (22.2%) patients, while the median number of relapse events was 3 (range 2–5) in 77.8% of the patients. Optic neuritis and transverse myelitis contributed equally as initial manifestations in three individuals (33%), while brainstem relapse was reported in two individuals (22%). The brain magnetic resonance imaging findings were compatible with McDonald's 2010 dissemination in space criteria in three cases (33%). Short myelitis and an (H)-sign were each documented in one patient.

Conclusion: The phenotypes of MOG Ab-positive cases exhibited overlapping features with MS and NMOSD. This finding highlights the importance of screening for anti-MOG in individuals with demyelinating symptoms, in consideration of the possibility of false-positive MOG Ab results.

Clinical and radiologic approach to 'typical' versus antibody-related optic neuritis

PURPOSE OF REVIEW

Optic neuritis is an autoimmune optic neuropathy that has been associated with multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and more recently antimyelin oligodendrocyte glycoprotein (anti-MOG)-positive disorder. At initial presentation, it is often difficult to differentiate these entities given their significant overlap in clinical presentation and MRI findings. This review summarizes the distinguishing clinical and radiological features of MS, NMOSD, and anti-MOG disorders to help clinicians accurately diagnose and manage patients affected by these conditions.

RECENT FINDINGS

Antiaquaporin-4 (AQP4) and more recently anti-MOG antibodies are both associated with central nervous system demyelinating diseases that often initially present with optic neuritis. Serologic testing now allows for a new classification of these overlapping conditions that can help to differentiate 'typical' optic neuritis that is often associated with MS from 'atypical' optic neuritis associated with NMOSD and anti-MOG-positive disorder.

SUMMARY

Optic neuritis associated with MS, NMOSD, and anti-MOG-positive disease can have a similar clinical presentation. However, some clinical and radiologic findings can help clinicians to differentiate these entities so that they can be properly managed to optimize visual prognosis.

Detection of autoantibodies in central nervous system inflammatory disorders: Clinical application of cell-based assays

The identification of autoantibodies in central nervous system (CNS) inflammatory disorders improves diagnostic accuracy and the identification of patients with a relapsing disease. Usual methods to detect autoantibodies are usually divided into 3 categories: tissue-based assays, protein-based assays and cell-based assays (CBA). Tissue-based assays are commonly used for initial identification of autoantibodies based on staining patterns and co-localization. Once the antigen is known, autoantibodies can be detected using other antigen-specific methods based on recombinant proteins and CBA using transfected cells expressing the protein in their cell membranes. Compared to traditional methods using recombinant proteins such as ELISA and western blot, the CBA have advantage of detecting conformational sensitive antibodies using natively folded proteins in the cell membrane. This article reviews the utility of CBA into the clinical practice.

Aged hind-limb clasping experimental autoimmune encephalomyelitis models aspects of the neurodegenerative process seen in multiple sclerosis

Experimental autoimmune encephalomyelitis (EAE) is the most common model of multiple sclerosis (MS). This model has been instrumental in understanding the events that lead to the initiation of central nervous system (CNS) autoimmunity. Though EAE has been an effective screening tool for identifying novel therapies for relapsing-remitting MS, it has proven to be less successful in identifying therapies for progressive forms of this disease. Though axon injury occurs in EAE, it is rapid and acute, making it difficult to intervene for the purpose of evaluating neuroprotective therapies. Here, we describe a variant of spontaneous EAE in the 2D2 T cell receptor transgenic mouse (2D2⁺ mouse) that presents with hind-limb clasping upon tail suspension and is associated with T cell-mediated inflammation in the posterior spinal cord and spinal nerve roots. Due to the mild nature of clinical signs in this model, we were able to maintain cohorts of mice into middle age. Over 9 mo, these mice exhibited a relapsing-remitting course of hind-limb clasping with the development of progressive motor deficits. Using a combined approach of ex vivo magnetic resonance (MR) imaging and histopathological analysis, we observed neurological progression to associate with spinal cord atrophy, synapse degradation, and neuron loss in the gray matter, as well as ongoing axon injury in the white matter of the spinal cord. These findings suggest that mild EAE coupled with natural aging may be a solution to better modeling the neurodegenerative processes seen in MS.

Characterization of the human myelin oligodendrocyte glycoprotein antibody response in demyelination

Over recent years, human autoantibodies targeting myelin oligodendrocyte glycoprotein (MOG Ab) have been associated with monophasic and relapsing central nervous system demyelination involving the optic nerves, spinal cord, and brain. While the clinical relevance of MOG Ab detection is becoming increasingly clear as therapeutic and prognostic differences from multiple sclerosis are acknowledged, an in-depth characterization of human MOG Ab is required to answer key challenges in patient diagnosis, treatment, and prognosis. Herein, we investigated the epitope, binding sensitivity, and affinity of MOG Ab in a cohort of 139 and 148 MOG antibody-seropositive children and adults (n = 287 patients at baseline, 130 longitudinal samples, and 22 cerebrospinal fluid samples). MOG extracellular domain was also immobilized to determine the affinity of MOG Ab. MOG Ab response was of immunoglobulin G1 isotype, and was of peripheral rather than intrathecal origin. High affinity MOG Ab were detected in 15% paediatric and 18% adult sera. More than 75% of paediatric and adult MOG Ab targeted a dominant extracellular antigenic region around Proline42. MOG Ab titers fluctuated over the progression of disease, but affinity and reactivity to Proline42 remained stable. Adults with a relapsing course intrinsically presented with a reduced immunoreactivity to Proline42 and had a more diverse MOG Ab response, a feature that may be harnessed for predicting relapse. Higher titers of MOG Ab were observed in more severe phenotypes and during active disease, supporting the pathogenic role of MOG Ab. Loss of MOG Ab seropositivity was observed upon conformational changes to MOG, and this greatly impacted the sensitivity of the detection of relapsing disorders, largely considered as more severe. Careful consideration of the binding characteristics of autoantigens should be taken into account when detecting disease-relevant autoantibodies.

The Glycosylation Site of Myelin Oligodendrocyte Glycoprotein Affects Autoantibody Recognition in a Large Proportion of Patients

Autoantibodies to myelin oligodendrocytes glycoprotein (MOG) are found in a fraction of patients with inflammatory demyelination and are detected with MOG-transfected cells. While the prototype anti-MOG mAb 8-18C5 and polyclonal anti-MOG responses from different mouse strains largely recognize the FG loop of MOG, the human anti-MOG response is more heterogeneous and human MOG-Abs recognizing different epitopes were found to be pathogenic. The aim of this study was to get further insight into details of antigen-recognition by human MOG-Abs focusing on the impact of glycosylation. MOG has one known N-glycosylation site at N31 located in the BC loop linking two beta-sheets. We compared the reactivity to wild type MOG with that toward two different mutants in which the neutral asparagine of N31 was mutated to negatively charged aspartate or to the neutral alanine. We found that around 60% of all patients (16/27) showed an altered reactivity to one or both of the mutations. We noted seven different patterns of recognition of the two glycosylation-deficient mutants by different patients. The introduced negative charge at N31 enhanced recognition in some, but reduced recognition in other patients. In 7/27 patients the neutral glycosylation-deficient mutant was recognized stronger. The folding of the extracellular domain of MOG with the formation of beta-sheets did not depend on its glycosylation as seen by circular dichroism. We determined the glycan structure of MOG produced in HEK cells by mass spectrometry. The most abundant glycoforms of MOG expressed in HEK cells are diantennary, contain a core fucose, an antennary fucose, and are decorated with α2,6 linked Neu5Ac, while details of the glycoforms of MOG in myelin remain to be identified. Together, we (1) increase the knowledge about heterogeneity of human autoantibodies to MOG, (2) show that the BC loop affects recognition in about 60% of the patients, (3) report that all patients recognized the unglycosylated protein backbone, while (4) in about 20% of the patients the attached sugar reduces autoantibody binding presumably via steric hindrance. Thus, a neutral glycosylation-deficient mutant of MOG might enhance the sensitivity to identify MOG-Abs.