Characterization of the human myelin oligodendrocyte glycoprotein antibody response in demyelination

Permeability of the blood-CSF barrier in MOGAD: clinical correlation based on the 2023 diagnostic criteria

BACKGROUND

The pathogenesis of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is associated with damage to the blood-cerebrospinal fluid (CSF) barrier (BCB), but a specific correlation remains unclear. We used the newly proposed diagnostic criteria in 2023 with the aim to evaluate the permeability of the BCB in MOGAD.

METHODS

We retrospectively analyzed data from 48 eligible patients with MOGAD. Serum and CSF samples were collected simultaneously prior to initiation of immunotherapies at admission. Elevated CSF/serum albumin quotient (QAlb) and indicators of intrathecal immunoglobulin G (IgG) synthesis were calculated as indicators of BCB damage. The relationship between the parameters and clinical features, disease severity, and prognosis were analyzed.

RESULTS

Elevated QAlb levels were detected in 50% of patients, but only a small proportion of patients met the corresponding classifications of intrathecal IgG synthesis, namely IgG index >0.7 (10.4%), IgG synthesis rate >10 (6.2%), and local IgG synthesis rate >0 (8.1%). Elevated QAlb was significantly more common in patients with myelitis than in those with optic neuritis (p = 0.049). It was identified as an independent predictor of moderate-severe disease at admission (modified Rankin Scale [mRS]/Expanded Disability Status Scale [EDSS] ≥ 4). Moreover, elevated QAlb emerged as an independent risk factor for a poor long-term prognosis (mRS/EDSS ≥3 at the last follow-up).

CONCLUSIONS

BCB damage was common in MOGAD. Elevated QAlb could serve as a biomarker for evaluating disease severity at admission and predicting long-term prognosis.

CD4-Positive T-Cell Responses to MOG Peptides in MOG Antibody-Associated Disease

To clarify T-cell responses in myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), we cultured the peripheral blood mononuclear cells of 24 patients with MOGAD and 20 with aquaporin-4 (AQP4) antibody-positive neuromyelitis optica spectrum disorders (NMOSD), and those of 17 healthy controls (HCs), in the presence of fourteen MOG peptides covering the full-length MOG, five AQP4 peptides, two myelin basic protein peptides, or two proteolipid protein peptides. Then, we measured T-cell activation markers, such as cell surface CD69 and the intracellular production of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon-γ in CD4-positive T-cells, with a flow cytometer. The expression of CD69 in response to MOG p16-40 and MOG p181-205 was significantly higher (Stimulation Index > 2) in MOGAD than in HCs. Also, CD69 for AQP4 p21-40, AQP4 p211-230, and MOG p166-190 were significantly increased in NMOSD than in HCs. Intracellular GM-CSF production responding to MOG p16-40 was significantly higher in MOGAD than in HCs (p < 0.05), although intracellular interferon-γ was not elevated. None of the responses to the other peptides were different between the groups. The present study showed subtle CD4-positive T-cell activation elicited by some MOG peptides alone in patients with MOGAD. Further studies of cytokines or other stimulation and alternative assay markers and metrics are needed to delineate the immunopathological roles of T-cells in MOGAD.

MOG antibody non-P42 epitope is associated with a higher risk of relapse in paediatric MOGAD

BACKGROUND

Biomarkers for predicting myelin oligodendrocyte glycoprotein antibody (Ab)-associated disease (MOGAD) clinical course are still missing. Binding capacity to a mutant MOG protein variant (MOG-P42S; non-P42) was shown to correlate with an increased relapse risk in adult patients.The objective of our study was to assess the frequency of binding to the non-P42 MOG variant in a cohort of paediatric MOGAD and to investigate its association with specific clinical profiles and disease course.

METHODS

We included children with MOG-Ab seropositive samples collected after their first demyelinating episode from five different centres. We performed live cell-based assays with native full-length MOG (MOG-FL) and mutant MOG-P42S and correlated the results with clinical data.

RESULTS

Of the 81 MOG-FL identified patients serum, 40 bound the non-P42 MOG. Non-P42 patients exhibited an earlier median age of onset (p=0.002). Phenotype distribution was different between groups (p=0.001), with non-P42 patients predominantly exhibiting acute disseminated encephalomyelitis phenotype. Notably, the non-P42 group was associated with a higher relapse rate (relative rate: 2.6 (95% CI 1.1 to 6.2), p=0.03), adjusted for clinical phenotype.

CONCLUSION

Non-P42 is a promising biomarker for predicting relapse in paediatric MOGAD patients.

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD): Insights into pathogenesis and biomarkers of prognosis

MOG antibody-associated disease (MOGAD), an inflammatory demyelinating pathology, is typically associated with the clinical phenotypes acute disseminated encephalomyelitis (ADEM), optic neuritis (ON), or transverse myelitis (TM). The mainstay of diagnosis is detection of antibodies targeting oligodendrocyte-expressed MOG (MOG-IgG). MOG-IgG-mediated demyelination occurs via complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), enhanced cognate T-cell CNS infiltration and activation, and oligodendrocyte cytoskeleton disruption, but the exact role of the immune system in MOGAD is still poorly understood. The disease course is either monophasic or relapsing, with relapsing course affecting approximately two-thirds of individuals. Neurological disability accumulates with relapse and may manifest as visual, motor, sensory, and cognitive deficits. Thus, accurate disease course prediction is of paramount importance. Prognostic biomarkers, implemented at a global scale, have the potential to guide timely therapeutic decisions to limit relapse-associated disability accrual while simultaneously avoiding unnecessary immunosuppression in monophasic individuals. This review explores recent insights in the understanding of MOGAD pathogenesis as well as advances in prognostic biomarkers of relapsing course and disease activity.

The Percentage of Neutrophils is Independently Associated with Blood-Brain Barrier(BBB) Disruption in Myelin Oligodendrocyte Glycoprotein Antibody Associated Disease (MOGAD)

Purpose

This study aims to investigate the risk factors associated with blood-brain barrier(BBB) disruption in patients with myelin oligodendrocyte glycoprotein antibody associated disease(MOGAD).

Patients and Methods

We collected clinical data from 95 patients diagnosed with MOGAD at the Department of Neurology, the First Affiliated Hospital of Zhengzhou University from October 2018 to May 2024. Patients were classified into normal or damaged BBB groups based on cerebrospinal fluid (CSF) albumin/serum albumin (QAlb). Binary logistic regression analysis was used to evaluate the risk factors for BBB disruption in MOGAD patients.

Results

Our study revealed that in MOGAD patients with BBB damaged, there is a higher proportion of acute phase high EDSS scores, higher incidence of prodromal symptoms, and a higher rate of viral infections. Myelitis is the main clinical phenotype, with clinical manifestations primarily including limb weakness and bladder/bowel dysfunction. Laboratory tests showed higher levels of CSF protein, immunoglobulin (IgG), 24-hour intrathecal IgG synthesis rate, peripheral blood leukocytes, neutrophil percentage, NLR, anti-thyroglobulin antibodies(TGAbs), and fibrinogen levels, while free triiodothyronine (FT3) and lymphocyte percentage were lower. Multivariate regression analysis indicated that an increased neutrophil percentage is an independent risk factor for BBB damage in MOGAD patients (OR=1.068, 95% CI: 1.018-1.122, P=0.008).

Conclusion

Neutrophil percentage is a readily available and widely used indicator reflecting the immune system's state and the body's inflammation level. The change in neutrophil percentage is independently associated with BBB damage in MOGAD patients. This finding helps provide more reference information for personalized treatment decisions and further research into the pathogenesis of MOGAD.

MOGAD: A comprehensive review of clinicoradiological features, therapy and outcomes in 4699 patients globally

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is one of the most common antibody-mediated CNS disorders. Optimal diagnostic and prognostic biomarkers remain unclear. Our aim was to clarify these biomarkers and therapeutic outcomes internationally. We reviewed articles from 2007 to 2022 and identified 194 unique cohorts encompassing 4699 paediatric and adult patients from 31 countries. Where phenotypes were specified, the most common initial presentation overall was optic neuritis (ON; paediatric 34 %; adults 60 %), during which 71 % had papilloedema on fundoscopy. The most common phenotype at latest follow-up was relapsing ON (20 %). Only 47 % of patients with 6-24 months of follow-up exhibited a relapsing course, while this proportion was much higher (72 %) when follow-up was extended beyond 5 years. Despite a similar relapse rate, the time to first relapse was much shorter in paediatric than adult patients (6 vs 17 months). Adult MRI-Brain scans performed at onset were more frequently normal than in paediatric patients (50 % vs 27 %). Abnormal MRI scans showing involvement of deep grey matter, cortico-subcortical, periventricular lesions, leptomeningeal enhancement, H-shaped spinal cord lesions, and bilateral optic nerve abnormalities were more common in paediatric patients compared to adults. Conversely, adults demonstrated higher frequencies of eccentric spinal cord lesions and intraorbital involvement. CSF analysis demonstrated intrathecally restricted oligoclonal bands in 12 %, elevated protein in 35 %, and pleocytosis in 54 %. Peripapillary retinal nerve fibre layer (pRNFL) thickness, measured acutely, frequently demonstrated swelling (weighted-median 145 μm; normal 85-110). Most cohorts demonstrated notable pRNFL atrophy at latest follow-up (weighted-median 67 μm). pRNFL thickness was significantly lower when measured at or after six months following ON onset, compared to measurements taken within the first six months following ON onset (p < 0.001). Therapeutic and outcome data was available for 3031 patients with a weighted-median disease duration of 32 months. Acute immunotherapy was initiated in 97 %, and maintenance immunotherapy in 64 %, with considerable regional variation. Expanded Disability Status Scale (EDSS) scores and visual acuities improved from nadir to latest follow-up in most patients. A negative correlation was noted between follow-up pRNFL thickness and latest follow-up visual acuity (r = -0.56). Based on this unprecedented global aggregation of MOGAD patients, we reveal a higher proportion of relapsing patients than previously recognised. While commonly used measures like EDSS show significant recovery, they underestimate visual disability following optic neuritis, the most frequent clinical presentation. Our findings suggest that RNFL thickness, especially when measured at least 6 months post-ON, may serve as a more sensitive biomarker for long-term visual impairment.

Oral corticosteroid dosage and taper duration at onset in myelin oligodendrocyte glycoprotein antibody-associated disease influences time to first relapse

BACKGROUND

We sought to identify an optimal oral corticosteroid regimen at the onset of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), which would delay time to first relapse while minimising cumulative corticosteroid exposure.

METHODS

In a retrospective multicentre cohort study, Cox proportional hazards models examined the relationship between corticosteroid course as a time-varying covariate and time to first relapse. Simon-Makuch and Kaplan-Meier plots identified an optimal dosing strategy.

RESULTS

We evaluated 109 patients (62 female, 57%; 41 paediatric, 38%; median age at onset 26 years, (IQR 8-38); median follow-up 6.2 years (IQR 2.6-9.6)). 76/109 (70%) experienced a relapse (median time to first relapse 13.7 months; 95% CI 8.2 to 37.9). In a multivariable model, higher doses of oral prednisone delayed time to first relapse with an effect estimate of 3.7% (95% CI 0.8% to 6.6%; p=0.014) reduced hazard of relapse for every 1 mg/day dose increment. There was evidence of reduced hazard of relapse for patients dosed ≥12.5 mg/day (HR 0.21, 95% CI 0.07 to 0.6; p=0.0036), corresponding to a 79% reduction in relapse risk. There was evidence of reduced hazard of relapse for those dosed ≥12.5 mg/day for at least 3 months (HR 0.12, 95% CI 0.03 to 0.44; p=0.0012), corresponding to an 88% reduction in relapse risk compared with those never treated in this range. No patient with this recommended dosing at onset experienced a Common Terminology Criteria for Adverse Events grade >3 adverse effect.

CONCLUSIONS

The optimal dose of 12.5 mg of prednisone daily in adults (0.16 mg/kg/day for children) for a minimum of 3 months at the onset of MOGAD delays time to first relapse.

MOG antibody-associated optic neuritis

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a demyelinating disorder, distinct from multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). MOGAD most frequently presents with optic neuritis (MOG-ON), often with characteristic clinical and radiological features. Bilateral involvement, disc swelling clinically and radiologically, and longitudinally extensive optic nerve hyperintensity with associated optic perineuritis on MRI are key characteristics that can help distinguish MOG-ON from optic neuritis due to other aetiologies. The detection of serum MOG immunoglobulin G utilising a live cell-based assay in a patient with a compatible clinical phenotype is highly specific for the diagnosis of MOGAD. This review will highlight the key clinical and radiological features which expedite diagnosis, as well as ancillary investigations such as visual fields, visual evoked potentials and cerebrospinal fluid analysis, which may be less discriminatory. Optical coherence tomography can identify optic nerve swelling acutely, and atrophy chronically, and may transpire to have utility as a diagnostic and prognostic biomarker. MOG-ON appears to be largely responsive to corticosteroids, which are often the mainstay of acute management. However, relapses are common in patients in whom follow-up is prolonged, often in the context of early or rapid corticosteroid tapering. Establishing optimal acute therapy, the role of maintenance steroid-sparing immunotherapy for long-term relapse prevention, and identifying predictors of relapsing disease remain key research priorities in MOG-ON.

Novel Genetic Variants Distinguishing Myelin Oligodendrocyte Glycoprotein-IgG-Positive From Myelin Oligodendrocyte Glycoprotein-IgG-Negative Pediatric Acute Disseminated Encephalomyelitis in Northern China

BACKGROUND

Acute disseminated encephalomyelitis (ADEM) is a common phenotype in children with myelin oligodendrocyte glycoprotein IgG (MOG-IgG)-associated disease. We aimed to identify novel genetic variants that distinguish children with MOG-IgG-positive ADEM (MOG-IgG+ ADEM) from children with MOG-IgG-negative ADEM (MOG-IgG- ADEM) using whole exome sequencing (WES) analysis.

METHODS

We conducted a two-stage study design. First, we performed WES on five patients with MOG-IgG+ ADEM and five patients with MOG-IgG- ADEM. Following bioinformatics analysis, the candidate variant list was constructed. Second, 29 children with MOG-IgG+ ADEM and 27 children with MOG-IgG- ADEM, together with discovery cohort, were genotyped to identify the novel variants.

RESULTS

WES resulted in 33,999 variants, and 5388 nonsynonymous variants were selected for downstream analysis. In total, 118 protein-affecting variants that were significantly different between the two groups were identified. Together with the five variants extracted from the literature, 49 variants were selected as the candidate variant list for genotyping in the replication cohort. Finally, we identified three variants: rs11171951 in NACα, rs231775 in CTLA4, and rs11171951 in GOLGA5, which were significantly different between MOG-IgG+ ADEM and MOG-IgG- ADEM. Only rs12440118 in NACα remained significant after Bonferroni correction for multiple testing (Padj < 0.001).

CONCLUSIONS

We identified strong associations between NACα, CTLA4, and GOLGA5 variants and MOG-IgG+ ADEM in a Han Chinese population of Northern China, which may present novel genetic risk factor distinguishing patients with MOG-IgG+ ADEM from those with MOG-IgG- ADEM.

Validation of the 2023 International Diagnostic Criteria for MOGAD in a Selected Cohort of Adults and Children

BACKGROUND AND OBJECTIVES

To test the performance of the 2023 myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) criteria in adults and children with inflammatory demyelinating conditions who were tested for MOG antibodies (Abs).

METHODS

This was a retrospective study of patients tested for MOG-Abs from 2018 to 2022 in 2 specialist hospitals. The inclusion criteria comprised ≥1 attendance in an adult or pediatric demyelinating disease clinic and complete clinical and MRI records. The final clinical diagnosis of MOGAD, made by the treating neurologist, was taken as the benchmark against which the new criteria were tested. The international MOGAD diagnostic criteria were applied retrospectively; they stipulate at least 1 clinical or MRI supporting feature for MOGAD diagnosis in positive fixed MOG cell-based assay without a titer. The performance MOG-Ab testing alone for MOGAD diagnosis was also assessed and compared with that of MOGAD criteria using the McNemar test.

RESULTS

Of the 1,879 patients tested for MOG-Abs, 539 (135 pediatric and 404 adults) met the inclusion criteria. A clinical diagnosis of MOGAD was made in 86/539 (16%) patients (37 adults, 49 children), with a median follow-up of 3.6 years. The MOGAD diagnostic criteria had sensitivity of 96.5% (adults 91.9%, children 100%), specificity of 98.9% (adults 98.8%, children 98.9%), positive predictive value of 94.3% (adults 89.4%, children 98%), negative predictive value of 99.3% (adults 99.2%, children 100%), and accuracy of 98.5% (adults 98.3%, children 99.2%). When compared with MOG-Ab testing alone, a difference was seen only in adults: a significantly higher specificity (98.9% vs 95.6%, p = 0.0005) and nonstatistically significant lower sensitivity (91.9% vs 100%, p = 0.08).

DISCUSSION

The international MOGAD diagnostic criteria exhibit high performance in selected patients with inflammatory demyelinating diseases (who had a high pretest probability of having MOGAD) compared with best clinical judgment; their performance was better in children than in adults. In adults, the MOGAD criteria led to an improvement in specificity and positive predictive value when compared with MOG-Ab testing alone, suggesting that the requirement of at least 1 clinical or MRI supporting feature is important. Future work should address the generalizability of the diagnostic criteria to cohorts of greater clinical diversity seen within neurologic settings.

The MOG antibody non-P42 epitope is predictive of a relapsing course in MOG antibody-associated disease

BACKGROUND

Myelin oligodendrocyte glycoprotein (MOG) IgG seropositivity is a prerequisite for MOG antibody-associated disease (MOGAD) diagnosis. While a significant proportion of patients experience a relapsing disease, there is currently no biomarker predictive of disease course. We aim to determine whether MOG-IgG epitopes can predict a relapsing course in MOGAD patients.

METHODS

MOG-IgG-seropositive confirmed adult MOGAD patients were included (n=202). Serum MOG-IgG and epitope binding were determined by validated flow cytometry live cell-based assays. Associations between epitopes, disease course, clinical phenotype, Expanded Disability Status Scale and Visual Functional System Score at onset and last review were evaluated.

RESULTS

Of 202 MOGAD patients, 150 (74%) patients had MOG-IgG that recognised the immunodominant proline42 (P42) epitope and 115 (57%) recognised histidine103/serine104 (H103/S104). Fifty-two (26%) patients had non-P42 MOG-IgG and showed an increased risk of a relapsing course (HR 1.7; 95% CI 1.15 to 2.60, p=0.009). Relapse-freedom was shorter in patients with non-P42 MOG-IgG (p=0.0079). Non-P42 MOG-IgG epitope status remained unchanged from onset throughout the disease course and was a strong predictor of a relapsing course in patients with unilateral optic neuritis (HR 2.7, 95% CI 1.06 to 6.98, p=0.038), with high specificity (95%, 95% CI 77% to 100%) and positive predictive value (85%, 95% CI 45% to 98%).

CONCLUSIONS

Non-P42 MOG-IgG predicts a relapsing course in a significant subgroup of MOGAD patients. Patients with unilateral optic neuritis, the most frequent MOGAD phenotype, can reliably be tested at onset, regardless of age and sex. Early detection and specialised management in these patients could minimise disability and improve long-term outcomes.

FLAMES overlaying anti-N-methyl-D-aspartate receptor encephalitis: a case report and literature review

BACKGROUND

In recent years, simultaneous or sequential occurrence of MOG antibody disease and anti-NMDAR encephalitis in the same patient has been reported with increasing frequency. Scholars refer to the overlapping occurrence of these two disorders as MOG antibody disease and anti-NMDAR encephalitis overlap syndrome (MNOS). Cortical T2-weighted fluid-attenuated inversion recovery (FLAIR) -hyperintense lesions in anti-MOG-associated encephalitis with seizures (FLAMES) is a rare clinical phenotype of MOGAD in which cortical FLAIR high-signal lesions are unilateral, with little spread to the cortex and meninges bilaterally. Although cases of FLAMES have been consistently reported. However, to our knowledge, such cases of FLAMES combined with NMDARE are rare.

CASE PRESENTATION

Here, we describe a case of FLAMES combined with anti-NMDARE. The patient was a young male, 29 years old, admitted to our hospital with isolated seizures, whose MRI showed unilateral thalamic and bilateral frontal and parietal leptomeningeal involvement. Since we were unaware of the possibility of bilateral meningo-cortical MOGAD manifestations, the case was initially diagnosed as viral encephalitis and was given antiviral therapy. The diagnosis was not clarified until anti-NMDAR-IgG and MOG-IgG positivity was detected in the cerebrospinal fluid and serum. The patient was then treated with high-dose corticosteroids and his symptoms responded well to the steroids. Therefore, this case expands the clinical spectrum of MNOS overlap syndrome. In addition, we describe the clinical features of MNOS by summarizing the existing literature and exploring the possible mechanisms of its immune response.

CONCLUSIONS

Our case serves as a reminder to clinicians that when patients present with atypical clinical manifestations such as seizures, consideration should be given to MNOS and conduct testing for various relevant autoantibodies (including MOG abs) and viruses in both serum and cerebrospinal fluid, as it is easy to misdiagnose the disease as other CNS diseases, such as viral meningoencephalitis. This syndrome exhibits a high responsiveness to steroids, highlighting the critical importance of recognizing the clinical and neuroimaging features of this overlap syndrome for prompt diagnosis and treatment. Furthermore, it enriches the disease spectrum of MNOS.

Mimicking the brain: Epstein-Barr virus and foreign agents as drivers of neuroimmune attack in multiple sclerosis

T cells have an essential role in adaptive immunity against pathogens and cancer, but failure of thymic tolerance mechanisms can instead lead to escape of T cells with the ability to attack host tissues. Multiple sclerosis (MS) occurs when structures such as myelin and neurons in the central nervous system (CNS) are the target of autoreactive immune responses, resulting in lesions in the brain and spinal cord which cause varied and episodic neurological deficits. A role for autoreactive T cell and antibody responses in MS is likely, and mounting evidence implicates Epstein-Barr virus (EBV) in disease mechanisms. In this review we discuss antigen specificity of T cells involved in development and progression of MS. We examine the current evidence that these T cells can target multiple antigens such as those from pathogens including EBV and briefly describe other mechanisms through which viruses could affect disease. Unravelling the complexity of the autoantigen T cell repertoire is essential for understanding key events in the development and progression of MS, with wider implications for development of future therapies.

Infection and Vaccine Induced Spike Antibody Responses Against SARS-CoV-2 Variants of Concern in COVID-19-Naïve Children and Adults

Although a more efficient adaptive humoral immune response has been proposed to underlie the usually favorable outcome of pediatric COVID-19, the breadth of viral and vaccine cross-reactivity toward the ever-mutating Spike protein among variants of concern (VOCs) has not yet been compared between children and adults. We assessed antibodies to conformational Spike in COVID-19-naïve children and adults vaccinated by BNT162b2 and ChAdOx1, and naturally infected with SARS-CoV-2 Early Clade, Delta, and Omicron. Sera were analyzed against Spike including naturally occurring VOCs Alpha, Beta, Gamma, Delta, and Omicron BA.1, BA.2, BA.5, BQ.1.1, BA2.75.2, and XBB.1, and variants of interest Epsilon, Kappa, Eta, D.2, and artificial mutant Spikes. There was no notable difference between breadth and longevity of antibody against VOCs in children and adults. Vaccinated individuals displayed similar immunoreactivity profiles across variants compared with naturally infected individuals. Delta-infected patients had an enhanced cross-reactivity toward Delta and earlier VOCs compared to patients infected by Early Clade SARS-CoV-2. Although Omicron BA.1, BA.2, BA.5, BQ.1.1, BA2.75.2, and XBB.1 antibody titers were generated after Omicron infection, cross-reactive binding against Omicron subvariants was reduced across all infection, immunization, and age groups. Some mutations, such as 498R and 501Y, epistatically combined to enhance cross-reactive binding, but could not fully compensate for antibody-evasive mutations within the Omicron subvariants tested. Our results reveal important molecular features central to the generation of high antibody titers and broad immunoreactivity that should be considered in future vaccine design and global serosurveillance in the context of limited vaccine boosters available to the pediatric population.

Pathogenesis, Clinical Features, and Treatment of Patients with Myelin Oligodendrocyte Glycoprotein (MOG) Autoantibody-Associated Disorders Focusing on Optic Neuritis with Consideration of Autoantibody-Binding Sites: A Review

Although there is a substantial amount of data on the clinical characteristics, diagnostic criteria, and pathogenesis of myelin oligodendrocyte glycoprotein (MOG) autoantibody-associated disease (MOGAD), there is still uncertainty regarding the MOG protein function and the pathogenicity of anti-MOG autoantibodies in this disease. It is important to note that the disease characteristics, immunopathology, and treatment response of MOGAD patients differ from those of anti-aquaporin 4 antibody-positive neuromyelitis optica spectrum disorders (NMOSDs) and multiple sclerosis (MS). The clinical phenotypes of MOGAD are varied and can include acute disseminated encephalomyelitis, transverse myelitis, cerebral cortical encephalitis, brainstem or cerebellar symptoms, and optic neuritis. The frequency of optic neuritis suggests that the optic nerve is the most vulnerable lesion in MOGAD. During the acute stage, the optic nerve shows significant swelling with severe visual symptoms, and an MRI of the optic nerve and brain lesion tends to show an edematous appearance. These features can be alleviated with early extensive immune therapy, which may suggest that the initial attack of anti-MOG autoantibodies could target the structures on the blood-brain barrier or vessel membrane before reaching MOG protein on myelin or oligodendrocytes. To understand the pathogenesis of MOGAD, proper animal models are crucial. However, anti-MOG autoantibodies isolated from patients with MOGAD do not recognize mouse MOG efficiently. Several studies have identified two MOG epitopes that exhibit strong affinity with human anti-MOG autoantibodies, particularly those isolated from patients with the optic neuritis phenotype. Nonetheless, the relations between epitopes on MOG protein remain unclear and need to be identified in the future.

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.

Clinical characteristics of myelin oligodendrocyte glycoprotein antibody-associated disease according to their epitopes

Background

The detection of myelin oligodendrocyte glycoprotein autoantibodies (MOG-Ab) is essential for the diagnosis of MOG-Ab-associated disease (MOGAD). The clinical implications of different epitopes recognized by MOG-Ab are largely unknown. In this study, we established an in-house cell-based immunoassay for detecting MOG-Ab epitopes and examined the clinical characteristics of patients with MOG-Ab according to their epitopes.

Methods

We conducted a retrospective review of patients with MOG-Ab-associated disease (MOGAD) in our single center registry, and collected serum samples from enrolled patients. Human MOG variants were generated to detect epitopes recognized by MOG-Ab. The differences in clinical characteristics according to the presence of reactivity to MOG Proline42 (P42) were evaluated.

Results

Fifty five patients with MOGAD were enrolled. Optic neuritis was the most common presenting syndrome. The P42 position of MOG was a major epitope of MOG-Ab. The patients with a monophasic clinical course and childhood-onset patients were only observed in the group that showed reactivity to the P42 epitope.

Conclusion

We developed an in-house cell-based immunoassay to analyze the epitopes of MOG-Ab. The P42 position of MOG is the primary target of MOG-Ab in Korean patients with MOGAD. Further studies are needed to determine the predictive value of MOG-Ab and its epitopes.

Biomarkers in autoimmune diseases of the central nervous system

The autoimmune diseases of the central nervous system (CNS) represent individual heterogeneity with different disease entities. Although clinical and imaging features make it possible to characterize larger patient cohorts, they may not provide sufficient evidence to detect disease activity and response to disease modifying drugs. Biomarkers are becoming a powerful tool due to their objectivity and easy access. Biomarkers may indicate various aspects of biological processes in healthy and/or pathological states, or as a response to drug therapy. According to the clinical features described, biomarkers are usually classified into predictive, diagnostic, monitoring and safety biomarkers. Some nerve injury markers, humoral markers, cytokines and immune cells in serum or cerebrospinal fluid have potential roles in disease severity and prognosis in autoimmune diseases occurring in the CNS, which provides a promising approach for clinicians to early intervention and prevention of future disability. Therefore, this review mainly summarizes the potential biomarkers indicated in autoimmune disorders of the CNS.

Dissection of complement and Fc-receptor-mediated pathomechanisms of autoantibodies to myelin oligodendrocyte glycoprotein

Autoantibodies against myelin oligodendrocyte glycoprotein (MOG) have recently been established to define a new disease entity, MOG-antibody-associated disease (MOGAD), which is clinically overlapping with multiple sclerosis. MOG-specific antibodies (Abs) from patients are pathogenic, but the precise effector mechanisms are currently still unknown and no therapy is approved for MOGAD. Here, we determined the contributions of complement and Fc-receptor (FcR)-mediated effects in the pathogenicity of MOG-Abs. Starting from a recombinant anti-MOG (mAb) with human IgG1 Fc, we established MOG-specific mutant mAbs with differential FcR and C1q binding. We then applied selected mutants of this MOG-mAb in two animal models of experimental autoimmune encephalomyelitis. First, we found MOG-mAb-induced demyelination was mediated by both complement and FcRs about equally. Second, we found that MOG-Abs enhanced activation of cognate MOG-specific T cells in the central nervous system (CNS), which was dependent on FcR-, but not C1q-binding. The identification of complement-dependent and -independent pathomechanisms of MOG-Abs has implications for therapeutic strategies in MOGAD.

Significance of Myelin Oligodendrocyte Glycoprotein Antibodies in CSF: A Retrospective Multicenter Study

BACKGROUND AND OBJECTIVES

Although the diagnosis of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is based on serum MOG antibodies (MOG-Abs) positivity, patients with coexisting or restricted MOG-Abs in the CSF have been reported. The aim of this study is to characterize the relevance of CSF MOG-Abs positivity in clinical practice.

METHODS

Eleven medical centers retrospectively collected clinical and laboratory data of adult and pediatric patients with suspected inflammatory CNS disease and MOG-Abs positivity in serum and/or CSF using live cell-based assays. Comparisons were performed using parametric or nonparametric tests, as appropriate. Potential factors of unfavorable outcomes were explored by Cox proportional hazard models and logistic regression.

RESULTS

The cohort included 255 patients: 139 (55%) women and 132 (52%) children (i.e., <18-year-old). Among them, 145 patients (56.8%) had MOG-Abs in both serum and CSF (MOG-Abs seropositive and CSF positive), 79 (31%) only in serum (MOG-Abs seropositive and CSF negative), and 31 (12%) only in CSF (MOG-Abs seronegative and CSF positive). MOG-Abs seronegative and CSF positive predominated in adults (22% vs 3% of children), presented more commonly with motor (n = 14, 45%) and sensory symptoms (n = 13, 42%), and all but 4 (2 multiple sclerosis, 1 polyradiculoneuritis, and 1 Susac syndrome) had a final diagnosis compatible with MOGAD. When comparing seropositive patients according to MOG-Abs CSF status, MOG-Abs seropositive and CSF positive patients had a higher Expanded Disability Status Scale (EDSS) at nadir during the index event (median 4.5, interquartile range [IQR] 3.0-7.5 vs 3.0, IQR 2.0-6.8, p = 0.007) and presented more commonly with sensory (45.5% vs 24%, p = 0.002), motor (33.6% vs 19%, p = 0.021), and sphincter symptoms (26.9% vs 7.8%, p = 0.001) than MOG-Abs seropositive and CSF negative. At the last follow-up, MOG-Abs seropositive and CSF positive cases had more often persistent sphincter dysfunction (17.3% vs 4.3%, p = 0.008). Compared with seropositive patients, those MOG-Abs seronegative and CSF positive had higher disability at the last follow-up (p ≤ 0.001), and MOG-Abs seronegative and CSF positive status were independently associated with an EDSS ≥3.0.

DISCUSSION

Paired serum and CSF MOG-Abs positivity are common in MOGAD and are associated with a more severe clinical presentation. CSF-only MOG-Abs positivity can occur in patients with a phenotype suggestive of MOGAD and is associated with a worse outcome. Taken together, these data suggest a clinical interest in assessing CSF MOG-Abs in patients with a phenotype suggestive of MOGAD, regardless of the MOG-Abs serostatus.

The Potential Pathogenicity of Myelin Oligodendrocyte Glycoprotein Antibodies in the Optic Pathway

BACKGROUND

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an acquired inflammatory demyelinating disease with optic neuritis (ON) as the most frequent clinical symptom. The hallmark of the disease is the presence of autoantibodies against MOG (MOG-IgG) in the serum of patients. Whereas the role of MOG in the experimental autoimmune encephalomyelitis animal model is well-established, the pathogenesis of the human disease and the role of human MOG-IgG is still not fully clear.

EVIDENCE ACQUISITION

PubMed was searched for the terms "MOGAD," "optic neuritis," "MOG antibodies," and "experimental autoimmune encephalomyelitis" alone or in combination, to find articles of interest for this review. Only articles written in English language were included and reference lists were searched for further relevant papers.

RESULTS

B and T cells play a role in the pathogenesis of human MOGAD. The distribution of lesions and their development toward the optic pathway is influenced by the genetic background in animal models. Moreover, MOGAD-associated ON is frequently bilateral and often relapsing with generally favorable visual outcome. Activated T-cell subsets create an inflammatory environment and B cells are necessary to produce autoantibodies directed against the MOG protein. Here, pathologic mechanisms of MOG-IgG are discussed, and histopathologic findings are presented.

CONCLUSIONS

MOGAD patients often present with ON and harbor antibodies against MOG. Furthermore, pathogenesis is most likely a synergy between encephalitogenic T and antibody producing B cells. However, to which extent MOG-IgG are pathogenic and the exact pathologic mechanism is still not well understood.

Diagnosis of myelin oligodendrocyte glycoprotein antibody-associated disease: International MOGAD Panel proposed criteria

Serum antibodies directed against myelin oligodendrocyte glycoprotein (MOG) are found in patients with acquired CNS demyelinating syndromes that are distinct from multiple sclerosis and aquaporin-4-seropositive neuromyelitis optica spectrum disorder. Based on an extensive literature review and a structured consensus process, we propose diagnostic criteria for MOG antibody-associated disease (MOGAD) in which the presence of MOG-IgG is a core criterion. According to our proposed criteria, MOGAD is typically associated with acute disseminated encephalomyelitis, optic neuritis, or transverse myelitis, and is less commonly associated with cerebral cortical encephalitis, brainstem presentations, or cerebellar presentations. MOGAD can present as either a monophasic or relapsing disease course, and MOG-IgG cell-based assays are important for diagnostic accuracy. Diagnoses such as multiple sclerosis need to be excluded, but not all patients with multiple sclerosis should undergo screening for MOG-IgG. These proposed diagnostic criteria require validation but have the potential to improve identification of individuals with MOGAD, which is essential to define long-term clinical outcomes, refine inclusion criteria for clinical trials, and identify predictors of a relapsing versus a monophasic disease course.

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.

Humoral signatures of MOG-antibody-associated disease track with age and disease activity

Myelin oligodendrocyte glycoprotein (MOG)-antibody (Ab)-associated disease (MOGAD) is an inflammatory demyelinating disease of the CNS. Although MOG is encephalitogenic in different mammalian species, the mechanisms by which human MOG-specific Abs contribute to MOGAD are poorly understood. Here, we use a systems-level approach combined with high-dimensional characterization of Ab-associated immune features to deeply profile humoral immune responses in 123 patients with MOGAD. We show that age is a major determinant for MOG-antibody-related immune signatures. Unsupervised clustering additionally identifies two dominant immunological endophenotypes of MOGAD. The pro-inflammatory endophenotype characterized by increased binding affinities for activating Fcγ receptors (FcγRs), capacity to activate innate immune cells, and decreased frequencies of galactosylated and sialylated immunoglobulin G (IgG) glycovariants is associated with clinically active disease. Our data support the concept that FcγR-mediated effector functions control the pathogenicity of MOG-specific IgG and suggest that FcγR-targeting therapies should be explored for their therapeutic potential in MOGAD.

[Clinical features and modern diagnostic criteria of the disease associated with myelin oligodendrocyte glycoprotein antibody disease]

Demyelinating disease of the central nervous system associated with antibodies to myelin oligodendrocyte glycoprotein (MOGAD) has been proposed to be distinguished from neuromyelitis optica spectrum disorders (NMOSD) into a separate nosological form. The basis for the recognition of nosological independence was the presence of clinical features of this disease and the detection of a specific biomarker in the blood serum of patients - IgG class antibodies to MOG. The article summarizes the current data on the clinical and radiological phenotypes of MOGAD in children and adults and the features of the course of the disease. The requirements for the laboratory diagnosis of the disease and diagnostic criteria for MOGAD proposed by an international group of experts in 2023 are given.

Tracking the clonal dynamics of SARS-CoV-2-specific T cells in children and adults with mild/asymptomatic COVID-19

Children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop less severe coronavirus disease 2019 (COVID-19) than adults. The mechanisms for the age-specific differences and the implications for infection-induced immunity are beginning to be uncovered. We show by longitudinal multimodal analysis that SARS-CoV-2 leaves a small footprint in the circulating T cell compartment in children with mild/asymptomatic COVID-19 compared to adult household contacts with the same disease severity who had more evidence of systemic T cell interferon activation, cytotoxicity and exhaustion. Children harbored diverse polyclonal SARS-CoV-2-specific naïve T cells whereas adults harbored clonally expanded SARS-CoV-2-specific memory T cells. A novel population of naïve interferon-activated T cells is expanded in acute COVID-19 and is recruited into the memory compartment during convalescence in adults but not children. This was associated with the development of robust CD4+ memory T cell responses in adults but not children. These data suggest that rapid clearance of SARS-CoV-2 in children may compromise their cellular immunity and ability to resist reinfection.

Treadmill aerobic training improve beam-walking test, up-regulate expression of main proteins of myelin and myelination in the hippocampus of cuprizone-fed mice

Multiple sclerosis (MS) is a potentially disabling disease of the brain and spinal cord (central nervous system). The aim of this study was to investigate the effect of 6 weeks of aerobic training on the main proteins of myelin including myelin basic protein (MBP), myelin oligodendrocyte (MOG), myelin associated glycoprotein (MAG), and myelin proteolipid protein (PLP) at hippocampus of C57BL/6 mouse model of cuprizone-induced MS. Twenty-eight female C57BL/6 mice (23 ± 3 g) were randomly divided into four groups (n = 7 per group): control, exercise (Exe), cuprizone (CPZ), and cuprizone with exercise (CPZ + Exe). Exercise groups performed treadmill aerobic exercise training 5 days a week, 15-22 m/min, and 15-60 min, during 6 weeks. Cuprizone were fed to mice at CPZ and CPZ + Exe groups for 6 weeks. Animals were sacrificed after 6 weeks. Biochemical and molecular biology analyses were performed. Mice at CPZ group had decreased myelination of nerve cells in the hippocampus. In addition, the use of CPZ in the hippocampus caused a decrease in the MBP, MOG gene expression, as well as a decrease in the MAG and PLP gene and protein expression compared to the healthy control group. However, performing aerobic exercise with CPZ consumption increased MBP gene expression and increased MAG and PLP protein expression, as well as increased myelination of nerve cells in the hippocampus compared to the CPZ group (p < 0.05). It seems that regular aerobic exercise in the MS model controls the destruction of myelin in the nerve cells of hippocampus by upregulating MBP, MAG and PLP, which can have positive effects on cognitive and motor performance.

Temporal Dynamics of MOG Antibodies in Children With Acquired Demyelinating Syndrome

BACKGROUND AND OBJECTIVE

The spectrum of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disorder (MOGAD) comprises monophasic diseases such as acute disseminated encephalomyelitis (ADEM), optic neuritis (ON), and transverse myelitis and relapsing courses of these presentations. Persistently high MOG antibodies (MOG immunoglobulin G [IgG]) are found in patients with a relapsing disease course. Prognostic factors to determine the clinical course of children with a first MOGAD are still lacking. The objective of the study is to assess the clinical and laboratory prognostic parameters for a risk of relapse and the temporal dynamics of MOG-IgG titers in children with MOGAD in correlation with clinical presentation and disease course.

METHODS

In this prospective multicenter hospital-based study, children with a first demyelinating attack and complete data set comprising clinical and radiologic findings, MOG-IgG titer at onset, and clinical and serologic follow-up data were included. Serum samples were analyzed by live cell-based assay, and a titer level of ≥1:160 was classified as MOG-IgG-positive.

RESULTS

One hundred sixteen children (f:m = 57:59) with MOGAD were included and initially diagnosed with ADEM (n = 59), unilateral ON (n = 12), bilateral ON (n = 16), myelitis (n = 6), neuromyelitis optica spectrum disorder (n = 8) or encephalitis (n = 6). The median follow-up time was 3 years in monophasic and 5 years in relapsing patients. There was no significant association between disease course and MOG-IgG titers at onset, sex, age at presentation, or clinical phenotype. Seroconversion to MOG-IgG-negative within 2 years of the initial event showed a significant risk reduction for a relapsing disease course. Forty-two/one hundred sixteen patients (monophasic n = 26, relapsing n = 16) had serial MOG-IgG testing in years 1 and 2 after the initial event. In contrast to relapsing patients, monophasic patients showed a significant decrease of MOG-IgG titers during the first and second years, often with seroconversion to negative titers. During the follow-up, MOG-IgG titers were persistently higher in relapsing than in monophasic patients. Decrease in MOG-IgG of ≥3 dilution steps after the first and second years was shown to be associated with a decreased risk of relapses. In our cohort, no patient experienced a relapse after seroconversion to MOG-IgG-negative.

DISCUSSION

In this study, patients with declining MOG-IgG titers, particularly those with seroconversion to MOG-IgG-negative, are shown to have a significantly reduced relapse risk.

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.

Patients with treated indolent lymphomas immunized with BNT162b2 have reduced anti-spike neutralizing IgG to SARS-CoV-2 variants, but preserved antigen-specific T cell responses

Patients with indolent lymphoma undertaking recurrent or continuous B cell suppression are at risk of severe COVID-19. Patients and healthy controls (HC; N = 13) received two doses of BNT162b2: follicular lymphoma (FL; N = 35) who were treatment naïve (TN; N = 11) or received immunochemotherapy (ICT; N = 23) and Waldenström's macroglobulinemia (WM; N = 37) including TN (N = 9), ICT (N = 14), or treated with Bruton's tyrosine kinase inhibitors (BTKi; N = 12). Anti-spike immunoglobulin G (IgG) was determined by a high-sensitivity flow-cytometric assay, in addition to live-virus neutralization. Antigen-specific T cells were identified by coexpression of CD69/CD137 and CD25/CD134 on T cells. A subgroup (N = 29) were assessed for third mRNA vaccine response, including omicron neutralization. One month after second BNT162b2, median anti-spike IgG mean fluorescence intensity (MFI) in FL ICT patients (9977) was 25-fold lower than TN (245 898) and HC (228 255, p = .0002 for both). Anti-spike IgG correlated with lymphocyte count (r = .63; p = .002), and time from treatment (r = .56; p = .007), on univariate analysis, but only with lymphocyte count on multivariate analysis (p = .03). In the WM cohort, median anti-spike IgG MFI in BTKi patients (39 039) was reduced compared to TN (220 645, p = .0008) and HC (p < .0001). Anti-spike IgG correlated with neutralization of the delta variant (r = .62, p < .0001). Median neutralization titer for WM BTKi (0) was lower than HC (40, p < .0001) for early-clade and delta. All cohorts had functional T cell responses. Median anti-spike IgG decreased 4-fold from second to third dose (p = .004). Only 5 of 29 poor initial responders assessed after third vaccination demonstrated seroconversion and improvement in neutralization activity, including to the omicron variant.

Pathomechanisms in demyelination and astrocytopathy: autoantibodies to AQP4, MOG, GFAP, GRP78 and beyond

PURPOSE OF REVIEW

The purpose of this review is to highlight the recently emerging pathomechanisms of diseases associated with autoantibodies to AQP4, MOG, GFAP, GRP78 and further novel targets. We discuss novel biomarkers and therapeutic approaches.

RECENT FINDINGS

Although complement-mediated cytotoxicity (CDC) is regarded as the major effector mechanism for AQP4-IgG in neuromyelitis optica spectrum disorders (NMOSD), recent studies helped to understand the relevance of complement-independent effector mechanisms. For MOG-IgG mediated diseases the role of CDC is less clear. MOG-IgG may trigger a tightly controlled FcR and BTK-driven microglia proliferative response in MOG-antibody-associated diseases. Differences of antibody-mediated tissue damage may reflect differential response to therapy. In addition, antibodies to GFAP, GRP78 and further novel targets have been implicated in demyelination and astrocytopathy.

SUMMARY

Elucidating the whole spectrum of effector functions in diseases mediated by AQP4-IgG and MOG-IgG and understanding the role of additional novel autoantibodies involved in demyelination and astrocytopathy may guide further novel treatment decisions.

BCG Vaccination: A potential tool against COVID-19 and COVID-19-like Black Swan incidents

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19), and its variants have brought unprecedented impacts to the global public health system, politics, economy, and other fields. Although more than ten COVID-19 specific vaccines have been approved for emergency use, COVID-19 prevention and control still face many challenges. Bacille Calmette–Guérin (BCG) is the only authorized vaccine used to fight against tuberculosis (TB), it has been hypothesized that BCG may prevent and control COVID-19 based on BCG-induced nonspecific immune responses. Herein, we summarized: 1) The nonspecific protection effects of BCG, such as prophylactic protection effects of BCG on nonmycobacterial infections, immunotherapy effects of BCG vaccine, and enhancement effect of BCG vaccine on unrelated vaccines; 2) Recent evidence of BCG's efficacy against SARS-COV-2 infection from ecological studies, analytical analyses, clinical trials, and animal studies; 3) Three possible mechanisms of BCG vaccine and their effects on COVID-19 control including heterologous immunity, trained immunity, and anti-inflammatory effect. We hope that this review will encourage more scientists to investigate further BCG induced non-specific immune responses and explore their mechanisms, which could be a potential tool for addressing the COVID-19 pandemic and COVID-19-like “Black Swan” events to reduce the impacts of infectious disease outbreaks on public health, politics, and economy.

Structural and functional markers of optic nerve damage in myelin oligodendrocyte glycoprotein antibody-associated optic neuritis

Background

Optic neuritis (ON) occurs in immune-mediated disorders including multiple sclerosis (MS), aquaporin-4 antibody-positive (AQP4) neuromyelitis optica spectrum disorder (AQP4-NMOSD) and myelin oligodendrocyte glycoprotein (MOG) antibody-associated demyelination (MOGAD). Accurate determination of aetiology is critical for appropriate treatment and prognostication.

Objective

To evaluate demyelination and axonal loss in MOG-ON to facilitate differentiation from MS-ON and AQP4-ON.

Methods

15 MOGAD patients with previous ON (25 eyes) underwent multifocal visual evoked potential (mfVEP) recordings and optical coherence tomography scans. Comparison was made to previously reported MS patients (n = 67, 69 eyes) and AQP4-NMOSD patients (n = 15, 23 eyes) with prior ON and healthy controls (n = 37, 74 eyes).

Results

MOG-ON patients had less retinal nerve fibre layer (RNFL) loss than AQP4-ON patients (p < 0.05) and less mfVEP latency prolongation than MS-ON patients (p < 0.01). Number of ON episodes in MOGAD was associated with reduced RNFL thickness (global, p = 0.07; temporal, p < 0.001) and mfVEP amplitude (p < 0.001). There was no abnormality in non-ON eyes.

Conclusions

Our study demonstrated a distinct pattern of damage in MOG-ON compared to AQP4-ON and MS-ON. ON in MOGAD produces less axonal loss than AQP4-NMOSD. Damage accumulates with relapses, supporting the role of maintenance immunosuppression to induce remission. Compared to MS, MOGAD causes less demyelination.

Myelin Oligodendrocyte Glycoprotein Antibody Associated Cerebral Cortical Encephalitis: Case Reports and Review of Literature

Myelin oligodendrocyte glycoprotein antibody-associated disease is an immune-mediated demyelinating disease of the central nervous system that is present in both adults and children. The most common clinical manifestations are optic neuritis, myelitis, acute disseminated encephalomyelitis, and brainstem syndrome. Cerebral cortical encephalitis (CCE) is a rare clinical phenotype of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), which usually begins with seizures, headaches, and fever, and may be misdiagnosed as viral encephalitis in the early stages. Herein, we report two typical MOG antibody (MOG-Ab)-positive patients presenting with CCE, both of whom presented with headache, fever, seizures, and who recovered completely after immunotherapy. In addition, we performed a systematic review of the present literature from the perspectives of population characteristics, clinical symptoms, MRI abnormalities, treatments, and prognosis. Among the patients reported in 25 articles, 33 met our inclusion criteria, with the age of onset ranging from 4 to 52 years. Most of the patients had seizures, headache, fever, and unilateral cortical lesions on brain MRI. For acute CCE, 30 patients were treated with high-dose intravenous methylprednisolone, and the symptoms of most patients were completely relieved after immunotherapy. This study reported our experience and lessons learned in the diagnosis and treatment of MOG-Ab-positive CCE and provides a systematic review of the literature to analyse this rare clinical phenotype.

Validation of a Flow Cytometry Live Cell-Based Assay to Detect Myelin Oligodendrocyte Glycoprotein Antibodies for Clinical Diagnostics

BACKGROUND

Myelin oligodendrocyte glycoprotein antibodies (MOG Ab) are essential in the diagnosis of MOG Ab-associated disease (MOGAD). Live cell-based assays (CBAs) are the gold standard for MOG Ab detection with improved sensitivity and specificity over fixed CBAs. A number of testing centers have used flow cytometry for its high throughput and quantitative utility. Presently, there is increasing demand to translate these research-based methods into an accredited routine diagnostic setting.

METHODS

A flow cytometry live CBA was used to detect MOG Ab in patients with demyelination. Serostatuses were compared between a research-based assay and a streamlined diagnostic assay. Inter-laboratory validation of the streamlined assay was performed in an accredited diagnostic laboratory. Further streamlining was performed by introducing a borderline serostatus range and reducing the number of controls used to determine the positivity threshold.

RESULTS

High serostatus agreement (98%-100%) was observed between streamlined and research-based assays. Intra- and inter-assay imprecision was improved in the streamlined assay (mean intra- and inter-assay CV = 7.3% and 27.8%, respectively) compared to the research-based assay (mean intra- and inter-assay CV = 11.8% and 33.6%, respectively). Borderline positive and clear positive serostatuses were associated with confirmed phenotypes typical of MOGAD. Compared to using 24 controls, robust serostatus classification was observed when using 13 controls without compromising analytical performance (93%-98.5% agreement).

CONCLUSIONS

Flow cytometry live CBAs show robust utility in determining MOG Ab serostatus. Streamlining and standardizing use of this assay for diagnostics would improve the accuracy and reliability of routine testing to aid diagnosis and treatment of patients with demyelination.

Complement Activation Is a Prominent Feature of MOGAD

Myelin oligodendrocyte glycoprotein (MOG)-antibody (Ab)-associated diseases (MOGADs) account for a substantial proportion of pediatric and adult patients who present with acquired demyelinating disorders. Its pathogenesis and optimal therapy are incompletely understood. We profiled systemic complement activation in adult and pediatric patients with MOGAD compared with patients with relapse-onset multiple sclerosis, patients with neuromyelitis optica spectrum disorder, and pediatric control and adult healthy donors. Proteins indicative of systemic classical and alternative complement activation were substantially increased in patients with MOGAD compared to control groups. Elevated levels were detected in both adult and pediatric cases and across all clinical syndromes. Complement inhibition should be explored for its therapeutic merit in patients with MOGAD. ANN NEUROL 2021;90:976-982.

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.

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.

SARS-CoV-2 neutralizing antibodies: Longevity, breadth, and evasion by emerging viral variants

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) antibody neutralization response and its evasion by emerging viral variants and variant of concern (VOC) are unknown, but critical to understand reinfection risk and breakthrough infection following vaccination. Antibody immunoreactivity against SARS-CoV-2 antigens and Spike variants, inhibition of Spike-driven virus-cell fusion, and infectious SARS-CoV-2 neutralization were characterized in 807 serial samples from 233 reverse transcription polymerase chain reaction (RT-PCR)-confirmed Coronavirus Disease 2019 (COVID-19) individuals with detailed demographics and followed up to 7 months. A broad and sustained polyantigenic immunoreactivity against SARS-CoV-2 Spike, Membrane, and Nucleocapsid proteins, along with high viral neutralization, was associated with COVID-19 severity. A subgroup of "high responders" maintained high neutralizing responses over time, representing ideal convalescent plasma donors. Antibodies generated against SARS-CoV-2 during the first COVID-19 wave had reduced immunoreactivity and neutralization potency to emerging Spike variants and VOC. Accurate monitoring of SARS-CoV-2 antibody responses would be essential for selection of optimal responders and vaccine monitoring and design.

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.

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.

[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.

Long-term persistence of RBD+ memory B cells encoding neutralizing antibodies in SARS-CoV-2 infection

Considerable concerns relating to the duration of protective immunity against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) exist, with evidence of antibody titers declining rapidly after infection and reports of reinfection. Here, we monitor the antibody responses against SARS-CoV-2 receptor-binding domain (RBD) for up to 6 months after infection. While antibody titers are maintained, ∼13% of the cohort’s neutralizing responses return to background. However, encouragingly, in a selected subset of 13 participants, 12 have detectable RBD-specific memory B cells and these generally are increasing out to 6 months. Furthermore, we are able to generate monoclonal antibodies with SARS-CoV-2 neutralizing capacity from these memory B cells. Overall, our study suggests that the loss of neutralizing antibodies in plasma may be countered by the maintenance of neutralizing capacity in the memory B cell repertoire.

Decay of antibody binding to RBD and spike antigen after 6 months

11 of 81 (13.6%) participants revert to background neutralizing levels

Despite declining antibody titers, robust memory B cell populations are observed

Memory B cells retain potent neutralizing capacity

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.

Opsoclonus myoclonus syndrome in a postpartum period

BACKGROUND

Opsoclonus-myoclonus syndrome (OMS) is a rare neuroimmunologic disorder characterized by opsoclonus, myoclonic jerks mostly in the face and limbs, cerebellar ataxia, tremors, and encephalopathy. OMS is rare in adults and exceedingly rarer in pregnancy, as only a few cases in pregnancy have been reported. We present what we understand is the first case of postpartum OMS.

METHODS AND RESULTS

We report and discuss a challenging case of OMS which started 6 weeks postpartum. Despite extensive infectious and malignancy evaluation, an underlying etiology was not readily apparent thus we treated her with high dose intravenous steroids and intravenous immunoglobulin (IVIG) for presumed idiopathic autoimmune OMS. She relapsed and additional workup identified new enhancing lesion on MRI brain, positive MOG-IgG, and CSF negative for oligoclonal bands. She was transitioned to maintenance IVIG and ultimately to rituximab with better results. At 2 year follow up her exam was improved and without objective evidence of abnormal movement or opsoclonus on maintenance Rituximab infusion 1,000 mg every 6 months.

CONCLUSION

In OMS, an autoimmune response is usually thought to occur by molecular mimicry with neuronal cell surface antigens in association with infections. Since a preceding infection was absent in this case, we propose that the immune response here was initiated due to immunological changes in pregnancy and postpartum period possibly due to fetal tissue exposure (fetal microchimerism). The presence of the MOG antibody raises the possibility that OMS is another clinical manifestation of MOG-associated disease (MOG-AD), which in our case is supported by characteristic CSF and radiographic findings of MOG-AD.

Single-cell approaches to investigate B cells and antibodies in autoimmune neurological disorders

Autoimmune neurological disorders, including neuromyelitis optica spectrum disorder, anti-N-methyl-D-aspartate receptor encephalitis, anti-MOG antibody-associated disorders, and myasthenia gravis, are clearly defined by the presence of autoantibodies against neurological antigens. Although these autoantibodies have been heavily studied for their biological activities, given the heterogeneity of polyclonal patient samples, the characteristics of a single antibody cannot be definitively assigned. This review details the findings of polyclonal serum and CSF studies and then explores the advances made by single-cell technologies to the field of antibody-mediated neurological disorders. High-resolution single-cell methods have revealed abnormalities in the tolerance mechanisms of several disorders and provided further insight into the B cells responsible for autoantibody production. Ultimately, several factors, including epitope specificity and binding affinity, finely regulate the pathogenic potential of an autoantibody, and a deeper appreciation of these factors may progress the development of targeted immunotherapies for patients.

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.

Archeological neuroimmunology: resurrection of a pathogenic immune response from a historical case sheds light on human autoimmune encephalomyelitis and multiple sclerosis

Aim of our study was to identify the target auto-antigen in the central nervous system recognized by the immune system of a unique patient, who died more than 60 years ago from a disease with pathological changes closely resembling multiple sclerosis (MS), following a misguided immunization with lyophilized calf brain tissue. Total mRNA was isolated from formaldehyde fixed and paraffin embedded archival brain tissue containing chronic active inflammatory demyelinating lesions with inflammatory infiltrates rich in B-lymphocytes and plasma cells. Analysis of the transcriptome by next generation sequencing and reconstruction of the dominant antibody by bioinformatic tools revealed the presence of one strongly expanded B-cell clone, producing an autoantibody against a conformational epitope of myelin oligodendrocytes glycoprotein (MOG), similar to that recognized by the well characterized monoclonal anti-MOG antibody 8-18C5. The reconstructed antibody induced demyelination after systemic or intrathecal injection into animals with T-cell mediated encephalomyelitis. Our study suggests that immunization with bovine brain tissue in humans may-in a small subset of patients-induce a disease with an intermediate clinical and pathological presentation between MS and MOG-antibody associated inflammatory demyelinating disease (MOGAD).