Myelin injury without astrocytopathy in neuroinflammatory disorders with MOG antibodies

Body fluid markers for multiple sclerosis and differential diagnosis from atypical demyelinating disorders

INTRODUCTION

Body fluid markers could be helpful to predict the conversion into clinically definite multiple sclerosis (MS) in people with a first demyelinating event of the central nervous system (CNS). Consequently, biomarkers such as oligoclonal bands, which are integrated in the current MS diagnostic criteria, could assist early MS diagnosis.

AREAS COVERED

This review examines existing knowledge on a broad spectrum of body fluid markers in people with a first CNS demyelinating event, explores their potential to predict conversion to MS, to assess MS disease activity, as well as their utility to differentiate MS from atypical demyelinating disorders such as neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein associated disease.

EXPERT OPINION

This field of research has shown a dramatic increase of evidence, especially in the last decade. Some biomarkers are already established in clinical routine (e.g. oligoclonal bands) while others are currently implemented (e.g. kappa free light chains) or considered as breakthroughs (e.g. neurofilament light). Determination of biomarkers poses challenges for continuous monitoring, especially if exclusively detectable in cerebrospinal fluid. A handful of biomarkers are measurable in blood which holds a significant potential.

Anti-aquaporin-4 immunoglobulin G/anti-myelin oligodendrocyte glycoprotein immunoglobulin G double-positive paraneoplastic neurological syndrome in a patient with triple-negative breast cancer

We report a rare case of paraneoplastic neurological syndrome with dual seropositivity of anti-aquaporin-4 and myelin oligodendrocyte glycoprotein antibodies in a 40 year-old woman with metastatic triple-negative breast cancer. She received multiple lines of anti-neoplastic treatment, including immunotherapy with pembrolizumab, as well as cytotoxic chemotherapy. Paraneoplastic meningoencephalomyelitis developed 2 years after diagnosis of breast cancer and 1 year after discontinuation of immunotherapy with pembrolizumab. She first developed longitudinally extending transverse myelitis followed by left optic neuritis and meningoencephalitis with new enhancing lesions in the brain and spinal leptomeninges. Cerebrospinal fluid analysis during both episodes showed normal glucose and protein, and elevated white blood cell count. Cytology was negative for malignancy. Cerebrospinal fluid was positive for neuromyelitis optica immunoglobulin G antibody anti-aquaporin-4, and autoimmune myelopathy panel was positive for myelin oligodendrocyte glycoprotein antibody. The patient had significant clinical and radiographic improvement after completion of five cycles of plasmapheresis followed by intravenous immunoglobulin. She did not have recurrence of paraneoplastic syndrome with maintenance rituximab every 6 months and daily low-dose prednisone. She succumbed to progressive systemic metastatic disease 4.5 years after her breast cancer diagnosis. This case shows that these antibodies can occur concurrently and cause clinical features, such as both neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody disease, in a patient with a singular type of cancer. We highlight the importance of testing for paraneoplastic etiology in cancer patients with radiographic menigoencephalomyelitis or meningitis with atypical symptoms of meningeal carcinomatosis and/or cerebrospinal fluid profile negative for leptomeningeal carcinomatosis.

A longitudinal analysis of brain volume changes in myelin oligodendrocyte glycoprotein antibody-associated disease

BACKGROUND AND PURPOSE

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a relapsing demyelinating condition. There are several cross-sectional studies showing evidence of brain atrophy in people with MOGAD (pwMOGAD), but longitudinal brain volumetric assessment is still an unmet need. Current recommendations do not include monitoring with MRI and assume distinct attacks. Evidence of ongoing axon loss will have diagnostic and therapeutic implications. In this study, we assessed brain volume changes in pwMOGAD over a mean follow-up period of 2 years and compared this to changes in people with multiple sclerosis (pwMS).

METHODS

This is a retrospective single-center study over a 7-year period from 2014 to 2021. MRI brain scans at the time of diagnosis and follow-up in remission were collected from 14 Caucasian pwMOGAD, confirmed by serum myelin oligodendrocyte glycoprotein immunoglobulin G antibody presence, detected by live cell-based assays. Total brain volume (TBV), white matter (WM), gray matter (GM), and demyelinating lesion volumes were assessed automatically using the Statistical Parametric Mapping and FMRIB automated segmentation tools. MRI brain scans at diagnosis and follow-up on remission were collected from 32-matched pwMS for comparison. Statistical analysis was done using analysis of variance.

RESULTS

There is evidence of TBV loss, affecting particularly GM, over an approximately 2-year follow-up period in pwMOGAD (p < .05), comparable to pwMS. WM and lesion volume change over the same period were not statistically significant (p > .1).

CONCLUSION

We found evidence of loss of GM and TBV over time  in pwMOGAD, similar to pwMS, although the WM and lesion volumes were unchanged.

Pathology of myelin oligodendrocyte glycoprotein antibody-associated disease: a comparison with multiple sclerosis and aquaporin 4 antibody-positive neuromyelitis optica spectrum disorders

Myelin oligodendrocyte glycoprotein (MOG) is expressed on the outermost layer of the myelin sheath in the central nervous system. Recently, the clinical concept of MOG antibody-associated disease (MOGAD) was established based on the results of human MOG-transfected cell-based assays which can detect conformation-sensitive antibodies against MOG. In this review, we summarized the pathological findings of MOGAD and discussed the issues that remain unresolved. MOGAD pathology is principally inflammatory demyelination without astrocyte destruction, characterized by perivenous demyelination previously reported in acute disseminated encephalomyelitis and by its fusion pattern localized in both the white and gray matter, but not by radially expanding confluent demyelination typically seen in multiple sclerosis (MS). Some of demyelinating lesions in MOGAD show severe loss of MOG staining compared with those of other myelin proteins, suggesting a MOG-targeted pathology in the disease. Perivascular cuffings mainly consist of macrophages and T cells with CD4-dominancy, which is also different from CD8+ T-cell-dominant inflammation in MS. Compared to aquaporin 4 (AQP4) antibody-positive neuromyelitis optica spectrum disorders (NMOSD), perivenous complement deposition is less common, but can be seen on myelinated fibers and on myelin degradation products within macrophages, resembling MS Pattern II pathology. Thus, the pathogenetic contribution of complements in MOGAD is still debatable. Together, these pathological features in MOGAD are clearly different from those of MS and AQP4 antibody-positive NMOSD, suggesting that MOGAD is an independent autoimmune demyelinating disease entity. Further research is needed to clarify the exact pathomechanisms of demyelination and how the pathophysiology relates to the clinical phenotype and symptoms leading to disability in MOGAD patients.

Helicobacter pylori infection may influence prevalence and disease course in myelin oligodendrocyte glycoprotein antibody associated disorder (MOGAD) similar to MS but not AQP4-IgG associated NMOSD

Background

Helicobacter pylori (Hp) persists after colonizing the gut in childhood, and potentially regulates host immune system through this process. Earlier studies have shown that Hp infection in childhood, may protect against MS in later life. Such an association was not seen with AQP4-IgG positive NMOSD, while the association with MOGAD is unclear.

Objective

To evaluate frequency of Hp IgG among patients with MOGAD, MS, NMOSD and matched controls and its effect on disease course. To ascertain whether childhood socio economic factors were linked to prevalence of Hp infection.

Methods

In all, 99 patients diagnosed to have MOGAD, 99 AQP4 IgG+ NMOSD, 254MS and 243 matched controls were included. Patient demographics, diagnosis, age at disease onset, duration and the last recorded expanded disability status scale (EDSS) were obtained from our records. Socioeconomic and educational status was queried using a previously validated questionnaire. Serum HpIgG was detected using ELISA kits (Vircell, Spain).

Result

Frequency of Hp IgG was significantly lower among MOGAD (28.3% vs 44%, p-0.007) and MS (21.2% vs 44%, p-0.0001) but not AQP4-IgG+ NMOSD patients (42.4% vs 44%, p-0.78) when compared to controls. Frequency of Hp IgG in MOGAD & MS patients combined (MOGAD-MS) was significantly lower than those with NMOSD (23.2% vs 42.4%, p- 0.0001). Seropositive patients with MOGAD- MS were older (p-0.001. OR -1.04, 95% CI- 1.01- 1.06) and had longer disease duration (p- 0.04, OR- 1.04, 95% CI- 1.002- 1.08) at time of testing. Educational status was lower among parents/caregivers of this study cohort (p- 0.001, OR -2.34, 95% CI- 1.48-3.69) who were Hp IgG+.

Conclusions

In developing countries Hp infection may be a significant environmental factor related to autoimmune demyelinating CNS disease. Our preliminary data suggests that Hp may exert a differential influence - a largely protective role for MS-MOGAD but not NMOSD and may influence disease onset and course. This differential response maybe related to immuno-pathological similarities between MOGAD and MS in contrast to NMOSD. Our study further underscores the role of Hp as a surrogate marker for poor gut hygiene in childhood and its association with later onset of autoimmune diseases.

Myelin Oligodendrocyte Glycoprotein as an Autoantigen in Inflammatory Demyelinating Diseases of the Central Nervous System

Demyelinating diseases of the central nervous system are caused by an autoimmune attack on the myelin sheath surrounding axons. Myelin structural proteins become antigenic, leading to the development of myelin lesions. The use of highly specialized laboratory diagnostic techniques for identification of specific antibodies directed against myelin components can significantly improve diagnostic approaches. Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) currently includes demyelinating syndromes with known antigens. Based on the demonstrated pathogenic role of human IgG against MOG, MOGAD was classified as a distinct nosological entity. However, generation of multiple MOG isoforms by alternative splicing hinders antigen detection even with the most advanced immunofluorescence techniques. On the other hand, MOG conformational changes ensure the structural integrity of other myelin proteins and maintain human-specific mechanisms of immune autotolerance.

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.

The Acute Optic Neuritis Network (ACON): Study protocol of a non-interventional prospective multicenter study on diagnosis and treatment of acute optic neuritis

Optic neuritis (ON) often occurs at the presentation of multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD). The recommended treatment of high-dose corticosteroids for ON is based on a North American study population, which did not address treatment timing or antibody serostatus. The Acute Optic Neuritis Network (ACON) presents a global, prospective, observational study protocol primarily designed to investigate the effect of time to high-dose corticosteroid treatment on 6-month visual outcomes in ON. Patients presenting within 30 days of the inaugural ON will be enrolled. For the primary analysis, patients will subsequently be assigned into the MS-ON group, the aquapotin-4-IgG positive ON (AQP4-IgG+ON) group or the MOG-IgG positive ON (MOG-IgG+ON) group and then further sub-stratified according to the number of days from the onset of visual loss to high-dose corticosteroids (days-to-Rx). The primary outcome measure will be high-contrast best-corrected visual acuity (HC-BCVA) at 6 months. In addition, multimodal data will be collected in subjects with any ON (CIS-ON, MS-ON, AQP4-IgG+ON or MOG-IgG+ON, and seronegative non-MS-ON), excluding infectious and granulomatous ON. Secondary outcomes include low-contrast best-corrected visual acuity (LC-BCVA), optical coherence tomography (OCT), magnetic resonance imaging (MRI) measurements, serum and cerebrospinal fluid (CSF) biomarkers (AQP4-IgG and MOG-IgG levels, neurofilament, and glial fibrillary protein), and patient reported outcome measures (headache, visual function in daily routine, depression, and quality of life questionnaires) at presentation at 6-month and 12-month follow-up visits. Data will be collected from 28 academic hospitals from Africa, Asia, the Middle East, Europe, North America, South America, and Australia. Planned recruitment consists of 100 MS-ON, 50 AQP4-IgG+ON, and 50 MOG-IgG+ON. This prospective, multimodal data collection will assess the potential value of early high-dose corticosteroid treatment, investigate the interrelations between functional impairments and structural changes, and evaluate the diagnostic yield of laboratory biomarkers. This analysis has the ability to substantially improve treatment strategies and the accuracy of diagnostic stratification in acute demyelinating ON.

Trial registration

ClinicalTrials.gov, identifier: NCT05605951.

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.

Novel CSF Biomarkers Tracking Autoimmune Inflammatory and Neurodegenerative Aspects of CNS Diseases

The accurate diagnosis of neuroinflammatory (NIDs) and neurodegenerative (NDDs) diseases and the stratification of patients into disease subgroups with distinct disease-related characteristics that reflect the underlying pathology represents an unmet clinical need that is of particular interest in the era of emerging disease-modifying therapies (DMT). Proper patient selection for clinical trials and identifying those in the prodromal stages of the diseases or those at high risk will pave the way for precision medicine approaches and halt neuroinflammation and/or neurodegeneration in early stages where this is possible. Towards this direction, novel cerebrospinal fluid (CSF) biomarker candidates were developed to reflect the diseased organ's pathology better. Μisfolded protein accumulation, microglial activation, synaptic dysfunction, and finally, neuronal death are some of the pathophysiological aspects captured by these biomarkers to support proper diagnosis and screening. We also describe advances in the field of molecular biomarkers, including miRNAs and extracellular nucleic acids known as cell-free DNA and mitochondrial DNA molecules. Here we review the most important of these novel CSF biomarkers of NIDs and NDDs, focusing on their involvement in disease development and emphasizing their ability to define homogeneous disease phenotypes and track potential treatment outcomes that can be mirrored in the CSF compartment.

FLAMES with Elevated Myelin Basic Protein Followed by Myelitis

The pathophysiology of unilateral cortical fluid-attenuated inversion recovery (FLAIR)-hyperintense lesions in anti-myelin oligodendrocyte glycoprotein (MOG)-associated encephalitis with seizures (FLAMES) is unclear. A 26-year-old man was referred because of a seizure. FLAIR showed an increased signal intensity and swelling of the right frontal cortex. His symptoms and imaging abnormalities were improved after intravenous methylprednisolone therapy. MOG antibody was detected both in serum and cerebrospinal fluid (CSF). Therefore, the patient was diagnosed with FLAMES. Myelin basic protein (MBP) was elevated in CSF. The high MBP value in the CSF in the present case suggested that demyelination as well as inflammation can occur in some FLAMES patients.

Neuromyelitis Optica Spectrum Disorder: From Basic Research to Clinical Perspectives

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system characterized by relapses and autoimmunity caused by antibodies against the astrocyte water channel protein aquaporin-4. Over the past decade, there have been significant advances in the biologic knowledge of NMOSD, which resulted in the IDENTIFICATION of variable disease phenotypes, biomarkers, and complex inflammatory cascades involved in disease pathogenesis. Ongoing clinical trials are looking at new treatments targeting NMOSD relapses. This review aims to provide an update on recent studies regarding issues related to NMOSD, including the pathophysiology of the disease, the potential use of serum and cerebrospinal fluid cytokines as disease biomarkers, the clinical utilization of ocular coherence tomography, and the comparison of different animal models of NMOSD.

CSF GFAP levels in double seronegative neuromyelitis optica spectrum disorder: no evidence of astrocyte damage

Background

Despite rigorous confirmation with reliable assays, some individuals showing the neuromyelitis optica spectrum disorder (NMOSD) phenotype remain negative for both aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies.

Objective

We aimed to investigate whether double seronegative NMOSD (DN-NMOSD) and NMOSD with AQP4 antibody (AQP4–NMOSD) share the same pathophysiological basis, astrocytopathy, by measurement of cerebrospinal fluid (CSF) glial fibrillary acidic protein (GFAP) levels as a marker of astrocyte damage.

Methods

Seventeen participants who (1) satisfied the 2015 diagnostic criteria for NMOSD, and (2) tested negative for AQP4 and MOG antibodies confirmed with repeated cell-based assays, and (3) had available CSF samples obtained at the point of clinical attacks, were enrolled from 4 medical centers (South Korea, Germany, Thailand, and Denmark). Thirty age-matched participants with AQP4–NMOSD, 17 participants with MOG antibody associated disease (MOGAD), and 15 participants with other neurological disorders (OND) were included as controls. The concentration of CSF GFAP was measured using enzyme-linked immunosorbent assay.

Results

CSF GFAP levels in the DN-NMOSD group were significantly lower than those in the AQP4–NMOSD group (median: 0.49 versus 102.9 ng/mL; p < 0.001), but similar to those in the OND (0.25 ng/mL) and MOGAD (0.39 ng/mL) control groups. The majority (90% (27/30)) of participants in the AQP4–NMOSD group showed significantly higher CSF GFAP levels than the highest level measured in the OND group, while no participant in the DN-NMOSD and MOGAD groups did.

Conclusions

These results suggest that DN-NMOSD has a different underlying pathogenesis other than astrocytopathy, distinct from AQP4–NMOSD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02450-w.

Magnetic Resonance Imaging of Autoimmune Demyelinating Diseases as a Diagnostic Challenge for Radiologists: Report of Two Cases and Literature Review

The magnetic resonance characteristics of autoimmune demyelinating diseases are complex and represent a challenge for the radiologist. In this study we presented two different cases of detected autoimmune demyelinating diseases: one case of acute disseminated encephalomyelitis and one case of neuromyelitis optica, respectively. Expected and unexpected findings of magnetic resonance imaging examination for autoimmune demyelinating diseases were reported in order to provide a valuable approach for diagnosis. In particular, we highlight, review and discuss the presence of several uncommon imaging findings which could lead to a misinterpretation. The integration of magnetic resonance imaging findings with clinical and laboratory data is necessary to provide a valuable diagnosis.

Serum and Cerebrospinal Fluid Biomarkers in Neuromyelitis Optica Spectrum Disorder and Myelin Oligodendrocyte Glycoprotein Associated Disease

The term neuromyelitis optica spectrum disorder (NMOSD) describes a group of clinical-MRI syndromes characterized by longitudinally extensive transverse myelitis, optic neuritis, brainstem dysfunction and/or, less commonly, encephalopathy. About 80% of patients harbor antibodies directed against the water channel aquaporin-4 (AQP4-IgG), expressed on astrocytes, which was found to be both a biomarker and a pathogenic cause of NMOSD. More recently, antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG), have been found to be a biomarker of a different entity, termed MOG antibody-associated disease (MOGAD), which has overlapping, but different pathogenesis, clinical features, treatment response, and prognosis when compared to AQP4-IgG-positive NMOSD. Despite important refinements in the accuracy of AQP4-IgG and MOG-IgG testing assays, a small proportion of patients with NMOSD still remain negative for both antibodies and are called “seronegative” NMOSD. Whilst major advances have been made in the diagnosis and treatment of these conditions, biomarkers that could help predict the risk of relapses, disease activity, and prognosis are still lacking. In this context, a number of serum and/or cerebrospinal fluid biomarkers are emerging as potentially useful in clinical practice for diagnostic and treatment purposes. These include antibody titers, cytokine profiles, complement factors, and markers of neuronal (e.g., neurofilament light chain) or astroglial (e.g., glial fibrillary acidic protein) damage. The aim of this review is to summarize current evidence regarding the role of emerging diagnostic and prognostic biomarkers in patients with NMOSD and MOGAD.

Case Report: Four Cases of Cortical/Brainstem Encephalitis Positive for Myelin Oligodendrocyte Glycoprotein Immunoglobulin G

AIM

Despite a significant improvement in the number of studies on myelin oligodendrocyte glycoprotein (MOG)-immunoglobulin G (IgG)-associated disorder (MOGAD) over the past few years, MOG-IgG-associated cortical/brainstem encephalitis remains a relatively uncommon and less-reported presentation among the MOGAD spectrum. This study aimed to report the clinical course, imaging features, and therapeutic response of MOG-IgG-associated cortical/brainstem encephalitis.

METHODS

Data of four patients who suffered from cortical encephalitis with epileptic seizures and/or brainstem encephalitis during the course of the disease were retrospectively collected and analyzed.

RESULTS

In this study, three male patients and one female patient, with a median age of onset of 21 years (ranging 20-51 years) were enrolled. An epileptic seizure was the main symptom of cortical encephalitis in these patients, while the manifestations of brainstem encephalitis were diverse. Cranial MRI demonstrated abnormal signals in unilateral or bilateral cortical or brainstem. Cerebrospinal fluid studies showed normal or mildly elevated leukocyte counts and protein levels, and a cell-based assay detected positive MOG-IgG in the serum of all patients. Two patients were misdiagnosed at the first attack, and both experienced a relapse. All of them accepted the first-line immunotherapy after a confirmed diagnosis and had a good outcome.

CONCLUSION

Early suspicion of MOG-IgG-associated encephalitis is necessary for any patient with sudden onset of seizures or symptoms of brainstem damage, especially with lesions on unilateral/bilateral cortical or brainstem on brain MRI.

Factors Associated With Relapse and Treatment of Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease in the United Kingdom

IMPORTANCE

Longer-term outcomes and risk factors associated with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are not well established.

OBJECTIVE

To investigate longer-term risk of relapse and factors associated with this risk among patients with MOGAD.

DESIGN, SETTING, AND PARTICIPANTS

This large, single-nation, prospective cohort study was conducted among 276 patients with MOGAD at 5 health care centers in the UK. Data from January 1973 to March 2020 were collected from 146 patients at Oxford and its outreach sites, 65 patients at Liverpool, 32 patients at a children's hospital in Birmingham, 22 patients at a children's hospital in London, and 11 patients at Cardiff, Wales. Data were analyzed from April through July 2020.

MAIN OUTCOMES AND MEASURES

Risk of relapse and annualized relapse rate were evaluated according to different baseline features, including onset age, onset phenotype, and incident vs nonincident group, with the incident group defined as patients diagnosed with antibodies against myelin oligodendrocyte glycoprotein before a second attack. Time to next relapse among patients experiencing relapse was measured and compared between the maintenance therapy subgroup and each first-line treatment group. The no-treatment group was defined as the off-treatment phase among patients who were relapsing, which could occur between any attack or between the last attack and last follow-up.

RESULTS

Among 276 patients with MOGAD, 183 patients were identified as being part of the incident group. There were no differences in mean (SD) onset age between total and incident groups (26.4 [17.6] years vs 28.2 [18.1] years), and female patients were predominant in both groups (166 [60.1%] female patients vs 106 [57.9%] female patients). The most common presentation overall was optic neuritis (ON) (119 patients among 275 patients with presentation data [43.3%]), while acute disseminated encephalomyelitis (ADEM), brain, or brainstem onset was predominant among 69 patients aged younger than 12 years (47 patients [68.1%]), including 41 patients with ADEM (59.4%). In the incident group, the 8-year risk of relapse was 36.3% (95% CI, 27.1%-47.5%). ON at onset was associated with increased risk of relapse compared with transverse myelitis at onset (hazard ratio [HR], 2.66; 95% CI, 1.01-6.98; P = .047), but there was no statistically significant difference with adjustment for a follow-on course of corticosteroids. Any TM at onset (ie, alone or in combination with other presentations [ie, ON or ADEM, brain, or brain stem]) was associated with decreased risk of relapse compared with no TM (HR, 0.41; 95% CI, 0.20-0.88; P = .01). Young adult age (ie, ages >18-40 years) was associated with increased risk of relapse compared with older adult age (ie, ages >40 years) (HR, 2.71; 95% CI, 1.18-6.19; P = .02). First-line maintenance therapy was associated with decreased risk of relapse when adjusted for covariates (prednisolone: HR, 0.33; 95% CI, 0.12-0.92; P = .03; prednisolone, nonsteroidal immunosuppressant, or combined: HR, 0.51; 95% CI, 0.28-0.92; P = .03) compared with the no-treatment group.

CONCLUSIONS AND RELEVANCE

The findings of this cohort study suggest that onset age and onset phenotype should be considered when assessing subsequent relapse risk and that among patients experiencing relapse, prednisolone, first-line immunosuppression, or a combination of those treatments may be associated with decreased risk of future relapse by approximately 2-fold. These results may contribute to individualized treatment decisions.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Current understanding of the epidemiologic and clinical characteristics of optic neuritis

Optic neuritis is an ocular disorder whose pathogenesis has not been fully determined, although autoimmune mechanisms have been suggested to be involved in its development. In recent years, anti-aquaporin-4 antibody (AQP4-Ab) and anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) have been shown to play major roles in the development of optic neuritis. Because these two antibodies target different tissues, optic neuritis can be classified by the type of antibody. AQP4-Ab-positive optic neuritis responds poorly to steroid therapy and has a poor prognosis in terms of visual acuity. On the other hand, MOG-Ab-positive optic neuritis responds favorably to steroid therapy but is likely to recur when the dosage of steroids is reduced or discontinued. We first present the high incidence of idiopathic optic neuritis and discuss these relatively newer disease concepts of AQP4-Ab-positive optic neuritis and MOG-Ab-positive optic neuritis.

Overlapping syndrome of anti-N-methyl-D-aspartate receptor encephalitis and anti-myelin oligodendrocyte glycoprotein inflammatory demyelinating diseases: A distinct clinical entity?

BACKGROUND

The co-existence of anti-N-methyl-D-aspartate receptor encephalitis (NMDARe) and anti-myelin oligodendrocyte glycoprotein (MOG) antibody disease has sparsely been reported, which needs to be investigated.

METHOD

Among the patients with NMDARe in Xuanwu Hospital, MOG antibody disease and NMDARe overlapping syndrome (MNOS) were retrospectively identified. We combined our data with those from previously reported cases to characterize this new entity.

RESULT

There were 45 patients with MNOS with a median onset age of 20. A total of 97.8% of the patients had symptoms of encephalitis; 68.9% of the patients had symptoms of demyelination, including optic neuritis (ON) (37.9%), longitudinally extensive transverse myelitis (LETM) (31.0%) and acute disseminated encephalomyelitis (ADEM) (27.6%). Abnormal signals on magnetic resonance imaging (MRI) usually involved cortical (46.7%), subcortical (31.1%) and basal ganglia (26.7%) lesions, as well as infratentorial (48.9%) and spinal cord (28.9%) lesions. No tumours were found. A total of 62.2% of the patients relapsed, with recurrence rates of 66.7% and 50.0% for those treated with first-line therapy alone and in combination with second-line immunotherapy, respectively. The pathological changes from the biopsy indicated immune-mediated inflammatory demyelination. Although some patients may have residual deficits, 93.3% of the patients became functionally independent.

CONCLUSION

The possibility of MNOS should be considered when patients diagnosed with anti-NMDARe simultaneously or sequentially develop ON, LETM or ADEM. MNOS occurred without tumour association, and inflammatory demyelination may be the pathological change. Steroids combined with second-line immunotherapy can help to reduce high recurrence rates, and most patients will have substantial recovery.

Serum Neurofilament Light and GFAP Are Associated With Disease Severity in Inflammatory Disorders With Aquaporin-4 or Myelin Oligodendrocyte Glycoprotein Antibodies

Objective: To evaluate the potential of serum neurofilament light (sNfL) and serum glial fibrillary acidic protein (sGFAP) as disease biomarkers in neuromyelitis optica spectrum disorder (NMOSD) with aquaporin-4 antibody (AQP4-ab) or myelin oligodendrocyte glycoprotein-antibody-associated disease (MOGAD). Methods: Patients with AQP4-ab-positive NMOSD (n = 51), MOGAD (n = 42), and relapsing-remitting multiple sclerosis (RRMS) (n = 31 for sNfL and n = 22 for sGFAP testing), as well as healthy controls (HCs) (n = 28), were enrolled prospectively. We assessed sNfL and sGFAP levels using ultrasensitive single-molecule array assays. Correlations of sNfL and sGFAP levels with clinical parameters were further examined in AQP4-ab-positive NMOSD and MOGAD patients. Results: sNfL levels were significantly higher in patients with AQP4-ab-positive NMOSD (median 17.6 pg/mL), MOGAD (27.2 pg/mL), and RRMS (24.5 pg/mL) than in HCs (7.4 pg/mL, all p < 0.001). sGFAP levels were remarkably increased in patients with AQP4-ab-positive NMOSD (274.1 pg/mL) and MOGAD (136.7 pg/mL) than in HCs (61.4 pg/mL, both p < 0.001). Besides, sGFAP levels were also significantly higher in patients with AQP4-ab-positive NMOSD compared to those in RRMS patients (66.5 pg/mL, p < 0.001). The sGFAP/sNfL ratio exhibited good discrimination among the three disease groups. sNfL levels increased during relapse in patients with MOGAD (p = 0.049) and RRMS (p < 0.001), while sGFAP levels increased during relapse in all three of the disease groups (all p < 0.05). Both sNfL and sGFAP concentrations correlated positively with Expanded Disability Status Scale scores in AQP4-ab-positive NMOSD (β = 1.88, p = 0.018 and β = 2.04, p = 0.032) and MOGAD patients (β = 1.98, p = 0.013 and β = 1.52, p = 0.008). Conclusion: sNfL and sGFAP levels are associated with disease severity in AQP4-ab-positive NMOSD and MOGAD patients, and the sGFAP/sNfL ratio may reflect distinct disease pathogenesis.

Clinical and Radiological Features of Adult Onset Bilateral Medial Frontal Cerebral Cortical Encephalitis With Anti-myelin Oligodendrocyte Glycoprotein Antibody

Objective: To clarify the clinical and radiological features of adult onset anti-myelin oligodendrocyte glycoprotein (MOG) antibody-associated bilateral medial frontal cerebral cortical encephalitis (BFCCE). Methods: We systematically reviewed the literature for patients with anti-MOG antibody-associated BFCCE. Patients who were also positive for other encephalitis-related autoantibodies were excluded from the study. The frequency of several characteristic neurological symptoms and lesion distributions were analyzed. Results: We identified six patients with anti-MOG antibody-associated BFCCE. Among them, 6/6 had headache, 4/6 had fever, 3/6 had seizure, 2/6 had paraparesis, 2/6 had lethargy, and 2/6 had memory disturbance. CSF pleocytosis was observed in 5/6 patients, while CSF myelin basic protein was not elevated in any of the six patients. On brain MRI, 6/6 had bilateral medial frontal cortical lesions, 3/6 had corpus callosum lesions, and 3/6 had leptomeningeal enhancements. Most of the lesions were distributed in the territory of the anterior cerebral artery (ACA). Conclusion: Our results indicate that anti-MOG antibody-associated BFCCE presents with characteristic clinical symptoms and MRI findings, which might reflect lesion formation in the ACA territory.

Myelin oligodendrocyte glycoprotein antibody-associated disease: an immunopathological study

Conformation-sensitive antibodies against myelin oligodendrocyte glycoprotein (MOG) are detectable in patients with optic neuritis, myelitis, opticomyelitis, acute or multiphasic disseminated encephalomyelitis (ADEM/MDEM) and brainstem/cerebral cortical encephalitis, but are rarely detected in patients with prototypic multiple sclerosis. So far, there has been no systematic study on the pathological relationship between demyelinating lesions and cellular/humoral immunity in MOG antibody-associated disease. Furthermore, it is unclear whether the pathomechanisms of MOG antibody-mediated demyelination are similar to the demyelination patterns of multiple sclerosis, neuromyelitis optica spectrum disorders (NMOSD) with AQP4 antibody, or ADEM. In this study, we immunohistochemically analysed biopsied brain tissues from 11 patients with MOG antibody-associated disease and other inflammatory demyelinating diseases. Patient median onset age was 29 years (range 9-64), and the median interval from attack to biopsy was 1 month (range 0.5-96). The clinical diagnoses were ADEM (n = 2), MDEM (n = 1), multiple brain lesions without encephalopathy (n = 3), leukoencephalopathy (n = 3) and cortical encephalitis (n = 2). All these cases had multiple/extensive lesions on MRI and were oligoclonal IgG band-negative. Most demyelinating lesions in 10 of 11 cases showed a perivenous demyelinating pattern previously reported in ADEM (153/167 lesions) and a fusion pattern (11/167 lesions) mainly in the cortico-medullary junctions and white matter, and only three lesions in two cases showed confluent demyelinated plaques. In addition, 60 of 167 demyelinating lesions (mainly in the early phase) showed MOG-dominant myelin loss, but relatively preserved oligodendrocytes, which were distinct from those of AQP4 antibody-positive NMOSD exhibiting myelin-associated glycoprotein-dominant oligodendrogliopathy. In MOG antibody-associated diseases, MOG-laden macrophages were found in the perivascular spaces and demyelinating lesions, and infiltrated cells were abundant surrounding multiple blood vessels in and around the demyelinating lesions, mainly consisting of macrophages (CD68; 1814 ± 1188 cells/mm2), B cells (CD20; 468 ± 817 cells/mm2), and T cells (CD3; 2286 ± 1951 cells/mm2), with CD4-dominance (CD4+ versus CD8+; 1281 ± 1196 cells/mm2 versus 851 ± 762 cells/mm2, P < 0.01). Humoral immunity, evidenced by perivascular deposits of activated complements and immunoglobulins, was occasionally observed in some MOG antibody-associated demyelinating lesions, and the frequency was much lower than that in AQP4 antibody-positive NMOSD. Subpial lesions with perivenous demyelination were observed in both ADEM and cortical encephalitis. Our study suggests that ADEM-like perivenous inflammatory demyelination with MOG-dominant myelin loss is a characteristic finding of MOG antibody-associated disease regardless of whether the diagnostic criteria of ADEM are met. These pathological features are clearly different from those of multiple sclerosis and AQP4 antibody-positive NMOSD, suggesting an independent autoimmune demyelinating disease entity.

MOG-IgG- versus AQP4-IgG-Positive Optic Neuritis in Thailand: Clinical Characteristics and Long-Term Visual Outcomes Comparison

Purpose

To compare demographic data, clinical and radiological characteristics, treatment, and long-term visual outcomes between myelin oligodendrocyte glycoprotein autoantibody-positive optic neuritis (MOG-IgG + ON) and aquaporin-4 autoantibody-positive optic neuritis (AQP4-IgG + ON) in Thailand.

Patients and Methods

We included individuals who were diagnosed with either MOG-IgG + ON or AQP4-IgG + ON over an 11-year period. Demographic data, clinical and radiological characteristics at ON presentation, treatment, and long-term visual outcomes were retrospectively collected.

Results

There were 16 patients (28 eyes) and 43 patients (59 eyes) in the MOG-IgG + ON and AQP4-IgG + ON groups, respectively. AQP4-IgG + ON occurred predominantly in female patients whereas MOG-IgG + ON-affected female patients and male patients equally (p < 0.001). Prior or concurrent non-ON demyelinating events were more often observed at AQP4-IgG + ON onset (p < 0.001). At ON presentation, bilaterality and the presence of optic disc edema were predominantly found in the MOG-IgG + ON group (bilaterality: 80% vs 8%, MOG-IgG + ON vs AQP4-IgG + ON patients, respectively (p < 0.001); presence of optic disc edema: 92.3% vs 36.6%, MOG-IgG + ON- vs AQP4-IgG + ON-affected eyes, respectively (p < 0.001)). There was no statistically significant difference in age at ON onset, nadir visual acuity (VA), presence of pain, segmental enhancement, and total enhanced segments of the anterior visual pathways. At the last follow-up, immunosuppressive drugs were used more often in the AQP4-IgG + ON group (43.7% vs 74.4%, MOG-IgG + ON vs AQP4-IgG + ON, respectively; p < 0.027). Remarkably better final VA was achieved in MOG-IgG + ON-affected eyes (median: 0.0 vs 0.4 logMAR, MOG-IgG + ON- vs AQP4-IgG + ON-affected eyes, respectively; p < 0.001).

Conclusion

Compared with AQP4-IgG + ON, MOG-IgG + ON tended to present with bilaterality and optic disc edema and demonstrated better visual outcomes.

Potential role of the gut microbiota in neuromyelitis optica spectrum disorder: Implication for intervention

The gut microbiota plays an important role in the occurrence and development of neuroimmunological diseases. Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease of the central nervous system that is characterized by the peripheral production of the disease-specific serum autoantibody aquaporin-4 (AQP4)-IgG. Recently, accumulating evidence has provided insights into the associations of gut microbiota dysbiosis and intestinal mucosal barrier destruction with NMOSD, but the underlying pathogenesis remains unclear. Thus, a microbiota intervention might be a potential therapeutic strategy for NMOSD by regulating the gut microbiota, repairing the intestinal mucosal barrier, and modulating intestinal immunity and peripheral immunity.

Oligodendrocyte myelin glycoprotein as a novel target for pathogenic autoimmunity in the CNS

Autoimmune disorders of the central nervous system (CNS) comprise a broad spectrum of clinical entities. The stratification of patients based on the recognized autoantigen is of great importance for therapy optimization and for concepts of pathogenicity, but for most of these patients, the actual target of their autoimmune response is unknown. Here we investigated oligodendrocyte myelin glycoprotein (OMGP) as autoimmune target, because OMGP is expressed specifically in the CNS and there on oligodendrocytes and neurons. Using a stringent cell-based assay, we detected autoantibodies to OMGP in serum of 8/352 patients with multiple sclerosis, 1/28 children with acute disseminated encephalomyelitis and unexpectedly, also in one patient with psychosis, but in none of 114 healthy controls. Since OMGP is GPI-anchored, we validated its recognition also in GPI-anchored form. The autoantibodies to OMGP were largely IgG1 with a contribution of IgG4, indicating cognate T cell help. We found high levels of soluble OMGP in human spinal fluid, presumably due to shedding of the GPI-linked OMGP. Analyzing the pathogenic relevance of autoimmunity to OMGP in an animal model, we found that OMGP-specific T cells induce a novel type of experimental autoimmune encephalomyelitis dominated by meningitis above the cortical convexities. This unusual localization may be directed by intrathecal uptake and presentation of OMGP by meningeal phagocytes. Together, OMGP-directed autoimmunity provides a new element of heterogeneity, helping to improve the stratification of patients for diagnostic and therapeutic purposes.

Biomarkers in Rare Demyelinating Disease of the Central Nervous System

Rare neurological diseases are a heterogeneous group corresponding approximately to 50% of all rare diseases. Neurologists are among the main specialists involved in their diagnostic investigation. At the moment, a consensus guideline on which neurologists may base clinical suspicion is not available. Moreover, neurologists need guidance with respect to screening investigations that may be performed. In this respect, biomarker research has emerged as a particularly active field due to its potential applications in clinical practice. With respect to autoimmune demyelinating diseases of the Central Nervous System (CNS), although these diseases occur in the frame of organ-specific autoimmunity, pathology of the disease itself is orchestrated among several anatomical and functional compartments. The differential diagnosis is broad and includes, but is not limited to, rare neurological diseases. Multiple Sclerosis (MS) needs to be differentially diagnosed from rare MS variants, Acute Disseminated Encephalomyelitis (ADEM), the range of Neuromyelitis Optica Spectrum Disorders (NMOSDs), Myelin Oligodendrocyte Glycoprotein (MOG) antibody disease and other systemic inflammatory diseases. Diagnostic biomarkers may facilitate timely diagnosis and proper disease management, preventing disease exacerbation due to misdiagnosis and false treatment. In this review, we will describe advances in biomarker research with respect to rare neuroinflammatory disease of the CNS.

E.U. paediatric MOG consortium consensus: Part 3 - Biomarkers of paediatric myelin oligodendrocyte glycoprotein antibody-associated disorders

A first episode of acquired demyelinating disorder (ADS) in children is a diagnostic challenge as different diseases can express similar clinical features. Recently, antibodies against myelin oligodendrocyte glycoprotein (MOG) have emerged as a new ADS biomarker, which clearly allow the identification of monophasic and relapsing ADS forms different from MS predominantly in children. Due to the novelty of this antibody there are still challenges and controversies about its pathogenicity and best technique to detect it. In this manuscript we will discuss the recommendations and caveats on MOG antibody assays, role in the pathogenesis, and additionally discuss the usefulness of other potential new biomarkers in MOG-antibody associated disorders (MOGAD).

[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.

Interleukin-6 in neuromyelitis optica spectrum disorder pathophysiology

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disorder that preferentially affects the spinal cord and optic nerve. Most patients with NMOSD experience severe relapses that lead to permanent neurologic disability; therefore, limiting frequency and severity of these attacks is the primary goal of disease management. Currently, patients are treated with immunosuppressants. Interleukin-6 (IL-6) is a pleiotropic cytokine that is significantly elevated in the serum and the CSF of patients with NMOSD. IL-6 may have multiple roles in NMOSD pathophysiology by promoting plasmablast survival, stimulating the production of antibodies against aquaporin-4, disrupting blood-brain barrier integrity and functionality, and enhancing proinflammatory T-lymphocyte differentiation and activation. Case series have shown decreased relapse rates following IL-6 receptor (IL-6R) blockade in patients with NMOSD, and 2 recent phase 3 randomized controlled trials confirmed that IL-6R inhibition reduces the risk of relapses in NMOSD. As such, inhibition of IL-6 activity represents a promising emerging therapy for the management of NMOSD manifestations. In this review, we summarize the role of IL-6 in the context of NMOSD.

CSF levels of glutamine synthetase and GFAP to explore astrocytic damage in seronegative NMOSD

OBJECTIVE

To explore levels of astrocytopathy in neuromyelitis optica spectrum disorder (NMOSD) by measuring levels of the astrocytic enzyme glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP), an established astrocytic biomarker known to be associated with disease activity in multiple sclerosis.

METHODS

Cerebrospinal fluid concentrations of GS and GFAP were measured by ELISA in patients with NMOSD (n=39, 28 aquaporin-4 (AQP4)-Ab-seropositive, 3 double-Ab-seronegative, 4 myelin oligodendrocyte glycoprotein (MOG)-Ab-seropositive and 4 AQP4-Ab-seronegative with unknown MOG-Ab-serostatus), multiple sclerosis (MS) (n=69), optic neuritis (n=5) and non-neurological controls (n=37).

RESULTS

GFAP and GS concentrations differed significantly across groups (both p<0.001), showing a similar pattern of elevation in patients with AQP4-Ab-seropositive NMOSD. GS and GFAP were significantly correlated, particularly in patients with AQP4-Ab-seropositive NMOSD (r_s=0.70, p<0.001). Interestingly, GFAP levels in some patients with double-Ab-seronegative NMOSD were markedly increased.

CONCLUSIONS

Our data indicate astrocytic injury occurs in some patients with double-Ab-seronegative NMOSD, which hints at the possible existence of yet undiscovered astrocytic autoimmune targets. We hypothesise that elevated GS and GFAP levels could identify those double-Ab-seronegative patients suitable to undergo in-depth autoimmune screening for astrocytic antibodies.

Seasonal distribution of attacks in aquaporin-4 antibody disease and myelin-oligodendrocyte antibody disease

BACKGROUND

Seasonal variation in incidence and exacerbations has been reported for neuroinflammatory conditions such as multiple sclerosis and acute disseminated encephalomyelitis (ADEM). It is unknown whether seasonality also influences aquaporin-4 antibody (AQP4-Ab) disease and myelin-oligodendrocyte antibody (MOG-Ab) disease.

OBJECTIVE

We examined the seasonal distribution of attacks in AQP4-Ab disease and MOG-Ab disease.

METHODS

Observational study using data prospectively recorded from three cohorts in the United Kingdom.

RESULTS

There was no clear seasonal variation in AQP4-Ab or MOG-Ab attacks for either the onset attack nor subsequent relapses. In both groups, the proportion of attacks manifesting with each of the main phenotypes (optic neuritis, transverse myelitis, ADEM/ADEM-like) appeared stable across the year. This study is the first to examine seasonal distribution of MOG-Ab attacks and the largest in AQP4-Ab disease so far.

CONCLUSION

Lack of seasonal distribution in AQP4-Ab and MOG-Ab disease may argue against environment factors playing a role in the aetiopathogenesis of these conditions.

[Anti-myelin oligodendrocyte glycoprotein antibody associated encephalitis]

The recent development of a cell-based assay that can detect specific autoantibodies revealed the clinical features of diseases associated with the anti-myelin oligodendrocyte glycoprotein (MOG) antibody. The anti-MOG antibody associated diseases may include inflammatory demyelinating central nervous system diseases such as neuromyelitis optica spectrum disorders, optic neuritis, myelitis, atypical multiple sclerosis, and encephalitis. Among them, anti-MOG antibody associated cortical encephalitis may develop seizure as one of the primary symptoms, present unique lateral or bilateral medial frontal cortical lesions on brain MRI FLAIR images. In acute phase, steroid pulse therapy and anti-epileptic drugs are required. In chronic phase, immunosuppressive drugs are often required to prevent relapses.

Myelin oligodendrocyte glycoprotein antibodies in neurological disease

Anti-myelin oligodendrocyte glycoprotein (MOG) antibodies (MOG-Abs) were first detected by immunoblot and enzyme-linked immunosorbent assay nearly 30 years ago, but their association with multiple sclerosis (MS) was not specific. Use of cell-based assays with native MOG as the substrate enabled identification of a group of MOG-Ab-positive patients with demyelinating phenotypes. Initially, MOG-Abs were reported in children with acute disseminated encephalomyelitis (ADEM). Further studies identified MOG-Abs in adults and children with ADEM, seizures, encephalitis, anti-aquaporin-4-antibody (AQP4-Ab)-seronegative neuromyelitis optica spectrum disorder (NMOSD) and related syndromes (optic neuritis, myelitis and brainstem encephalitis), but rarely in MS. This shift in our understanding of the diagnostic assays has re-invigorated the examination of MOG-Abs and their role in autoimmune and demyelinating disorders of the CNS. The clinical phenotypes, disease courses and responses to treatment that are associated with MOG-Abs are currently being defined. MOG-Ab-associated disease is different to AQP4-Ab-positive NMOSD and MS. This Review provides an overview of the current knowledge of MOG, the metrics of MOG-Ab assays and the clinical associations identified. We collate the data on antibody pathogenicity and the mechanisms that are thought to underlie this. We also highlight differences between MOG-Ab-associated disease, NMOSD and MS, and describe our current understanding on how best to treat MOG-Ab-associated disease.

Quantitative brain lesion distribution may distinguish MOG-ab and AQP4-ab neuromyelitis optica spectrum disorders

OBJECTIVES

Antibodies to myelin oligodendrocyte glycoprotein (MOG-ab) and antibodies to aquaporin-4 (AQP4-ab) have been suggested to play roles in commonly separated subsets of patients with neuromyelitis optica spectrum disorder (NMOSD) phenotypes. The aim of this study is to quantitatively delineate and compare the brain lesion distributions of AQP4-ab-positive and MOG-ab-positive patients.

METHODS

Fifty-seven and twenty-eight clinical MRI scans were collected from fifty-two AQP4-ab-positive and twenty-four MOG-ab-positive patients, respectively. T2 lesions were segmented manually on each axial FLAIR image. Probabilistic lesion distribution maps were created for each group after spatial normalization. Lobe-wise and voxel-wise quantitative comparisons of the two distributions were performed. A classification model based on the lesion distribution features was constructed to differentiate the two patient groups.

RESULTS

Infratentorial and supratentorial brain lesions were found in both AQP4-ab-positive and MOG-ab-positive patients, with large inter-group overlap mainly in deep white matter (WM). In comparison with those in the AQP4 group, the brain lesions of the MOG-ab-positive patients had a larger size, dispersed distribution, and higher probabilities in the cerebellum, pons, midbrain, and GM and juxtacortical WM in temporal, sublobar, frontal, and parietal lobes. The area under the receiver operating characteristic curve of the lesion-distribution-based classification model was 0.951.

CONCLUSIONS

MOG-ab-positive and AQP4-ab-positive groups showed similar but quantitatively different brain lesion distributions. These results may help clinicians in considering MOG versus AQP4 in initial diagnosis, and add rationale for sending corresponding serologic testing.

KEY POINTS

• Brain lesion distributions of AQP-ab-positive and MOG-ab-positive NMOSD patients • Larger size, dispersed distribution, higher lesion probabilities in the cerebellum, pons, midbrain, and GM and juxtacortical WM in the MOG group • The lesion-distribution-based classification model differentiates the two groups with AUC = 0.951.

Classifying the antibody-negative NMO syndromes: Clinical, imaging, and metabolomic modeling

Objective

To determine whether unsupervised principal component analysis (PCA) of comprehensive clinico-radiologic data can identify phenotypic subgroups within antibody-negative patients with overlapping features of multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSDs), and to validate the phenotypic classifications using high-resolution nuclear magnetic resonance (NMR) plasma metabolomics with inference to underlying pathologies.

Methods

Forty-one antibody-negative patients were recruited from the Oxford NMO Service. Thirty-six clinico-radiologic parameters, focusing on features known to distinguish NMOSD and MS, were collected to build an unbiased PCA model identifying phenotypic subgroups within antibody-negative patients. Metabolomics data from patients with relapsing-remitting MS (RRMS) (n = 34) and antibody-positive NMOSD (Ab-NMOSD) (aquaporin-4 antibody n = 54, myelin oligodendrocyte glycoprotein antibody n = 20) were used to identify discriminatory plasma metabolites separating RRMS and Ab-NMOSD.

Results

PCA of the 36 clinico-radiologic parameters revealed 3 phenotypic subgroups within antibody-negative patients: an MS-like subgroup, an NMOSD-like subgroup, and a low brain lesion subgroup. Supervised multivariate analysis of metabolomics data from patients with RRMS and Ab-NMOSD identified myoinositol and formate as the most discriminatory metabolites (both higher in RRMS). Within antibody-negative patients, myoinositol and formate were significantly higher in the MS-like vs NMOSD-like subgroup; myoinositol (mean [SD], 0.0023 [0.0002] vs 0.0019 [0.0003] arbitrary units [AU]; p = 0.041); formate (0.0027 [0.0006] vs 0.0019 [0.0006] AU; p = 0.010) (AU).

Conclusions

PCA identifies 3 phenotypic subgroups within antibody-negative patients and that the metabolite discriminators of RRMS and Ab-NMOSD suggest that these groupings have some pathogenic meaning. Thus, the identified clinico-radiologic discriminators may provide useful diagnostic clues when seeing antibody-negative patients in the clinic.

Overlapping demyelinating syndrome and anti-N-methyl-d-aspartate receptor encephalitis with seizures

Anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis, the most recognized type of autoimmune encephalitis, manifests with rapid cognitive decline, psychosis, and seizures that develop in 78–86% of patients. Recently, anti-NMDAR encephalitis was reported in association with demyelinating diseases which are accompanied by a characteristic clinical phenotype, imaging abnormalities, and the presence of antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) in bodily fluids. The patient presented herein suffered from bilateral optic neuritis followed by recurrent encephalitis with focal seizures and demonstrated anti-NMDAR and MOG-IgGs in the cerebrospinal fluid and serum, respectively. Her symptoms responded to immunotherapy and antiseizure medication. The recognition of the novel syndrome of MOG antibody-associated demyelination (MOGAD), encompassing the overlapping anti-NMDAR encephalitis and other MOG-IgG associated disorders, is important for the successful management of these patients.

•

Recurrent anti-N-methyl-d-aspirate (NMDA) receptor encephalitis with seizures may follow an acute demyelinating disease

•

In overlap syndrome, anti-NMDA receptor antibodies and antibodies against myelin oligodendrocyte glycoprotein may be detected in the bodily fluids

•

Recognition of the overlap syndrome is important to determine the optimal treatment and ensure the prevention of relapse

[Longitudinally extensive transverse myelitis involving fifteen vertebral bodies positive for anti-myelin oligodendrocyte glycoprotein (MOG) antibody: a case report]

A 16-year-old male with no previous medical history developed sudden fever and urinary dysfunction. He was admitted to our hospital due to bilateral leg weakness and sensory disturbance on the third day of weakness onset. A sagittal T₂-weighted image displayed a longitudinal extensive lesion of transverse myelitis in the spinal column from the upper cervical (C2) to the thoracic region (Th9). The patient was diagnosed with autoimmune myelitis and treated with four courses of intravenous methylprednisolone (1 g/day for three consecutive days per week). This improved his signs, and his serum sample tested negative for anti-aquaporin-4 (AQP-4) antibody but positive for anti-myelin oligodendrocyte glycoprotein (MOG) antibody in cell-based assays. We report this case of longitudinally extensive transverse myelitis involving fifteen vertebral bodies positive for anti-MOG antibody.

Neuromyelitis optica spectrum disorders: still evolving and broadening

PURPOSE OF REVIEW

The diagnostic criteria of neuromyelitis optica spectrum disorders (NMOSD) has been revised in the past 20 years and pathological and therapeutic data have been accumulated. This review provides an overview of evolution and broadening of the concept of NMOSD.

RECENT FINDINGS

NMOSD encompassing brain syndrome as well as optic neuritis and acute myelitis is now classified into aquaporine-4 (AQP)-antibody-seropositive and aquaporine-4 (AQP)-antibody-seronegative diseases, detecting more patients earlier than before. Seronegative NMOSD includes cases of myelin oligodendrocyte glycoprotein (MOG)-antibody-seropositive disease with its unique clinical spectrum somewhat different from AQP4-antibody-seropositive NMOSD. Pathologically, NMOSD includes AQP4-antibody-seropositive autoimmune astrocytopathic disease and MOG-antibody-seropositive inflammatory demyelinating disease. Double seronegative group needs further research. Therapeutic options of NMOSD has taken shape and first-ever clinical trials of monoclonal antibodies have been done. In retrospect, relapsing NMO in the studies preceding the discovery of AQP4-antibody had features of AQP4-antibody-seropositive NMO whereas monophasic NMO was similar to AQP4-antibody-seronegative/MOG-antibody-seropositive NMO.

SUMMARY

The clinical, pathological and therapeutic concepts of NMOSD have evolved and broadened over the last two decades following the detection of AQP4 antibodies and MOG antibodies in the patients. Double seronegative NMOSD is a current research focus, but now we may need to reconsider how NMOSD should be defined.

MOG antibody-associated encephalomyelitis/encephalitis

Myelin oligodendrocyte glycoprotein (MOG) antibody disease is a rare autoimmune disorder with antibodies against the MOG predominantly involving the optic nerve and spinal cord leading to vision loss and paralysis. When MOG antibody disease involves the brain, the phenotype is similar to acute disseminated encephalomyelitis (ADEM). In this review, we discuss MOG-positive cases presenting with encephalitis, encephalopathy, or ADEM-like presentation based on recently published series.

Mechanisms for lesion localization in neuromyelitis optica spectrum disorders

Purpose of review

Neuromyelitis optica spectrum disorders (NMOSD) are severe inflammatory diseases of the central nervous system (CNS), with the presence of aquaporin 4 (AQP4)-specific serum antibodies in the vast majority of patients, and with the presence of myelin oligodendrocyte glycoprotein (MOG)-specific antibodies in approximately 40% of all AQP4-antibody negative NMOSD patients. Despite differences in antigen recognition, the preferred sites of lesions are similar in both groups of patients: They localize to the spinal cord and to the anterior visual pathway including retina, optic nerves, chiasm, and optic tracts, and – to lesser extent – also to certain predilection sites in the brain.

Recent findings

The involvement of T cells in the formation of NMOSD lesions has been challenged for quite some time. However, several recent findings demonstrate the key role of T cells for lesion formation and localization. Studies on the evolution of lesions in the spinal cord of NMOSD patients revealed a striking similarity of early NMOSD lesions with those observed in corresponding T-cell-induced animal models, both in lesion formation and in lesion localization. Studies on retinal abnormalities in NMOSD patients and corresponding animals revealed the importance of T cells for the very early stages of retinal lesions which eventually culminate in damage to Müller cells and to the retinal nerve fiber layer. Finally, a study on cerebrospinal fluid (CSF) barrier pathology demonstrated that NMOSD immunopathology extends beyond perivascular astrocytic foot processes to include the pia, the ependyma, and the choroid plexus, and that diffusion of antibodies from the CSF could further influence lesion formation in NMOSD patients.

Summary

The pathological changes observed in AQP4-antibody positive and MOG-antibody positive NMOSD patients are strikingly similar to those found in corresponding animal models, and many mechanisms which determine lesion localization in experimental animals seem to closely reflect the human situation.