Cerebrospinal fluid antibodies to aquaporin-4 in neuromyelitis optica and related disorders: frequency, origin, and diagnostic relevance

Small RNA sequencing of differentiated astrocytoma exposed to NMOSD patient sera reveals perturbations in neurodegenerative signaling

The signaling pathways behind severe astrocytic lysis with Aquaporin4 auto-antibody (AQP4-IgG) seropositivity, and reactive astrocytosis with myelin oligodendrocyte glycoprotein auto-antibody (MOG-IgG) seropositivity, remain largely unexplored in Neuromyelitis optica spectrum disorder (NMOSD), while almost no molecular details being known about double-seronegative (DN) patients. Recent discovery of glial fibrillary acidic protein (GFAP) in DN NMOSD patients' cerebrospinal fluid, akin to AQP4-IgG + ve cases, suggests astrocytopathy. Here, we aim to study small non coding RNA (sncRNA) signature alterations in astrocytes exposed to AQP4-IgG + ve and MOG-IgG + ve patient sera, and their potential resemblance with DN-NMOSD. Next Generation Sequencing (NGS) revealed differential expression of several microRNAs with notable alterations in hsa-miR-6824-3p, hsa-miR-324-5p and hsa-miR-4466 respectively upon sera treatment. Results with DN-NMOSD patient sera are majorly similar to that of AQP4+ve sera. Strikingly, in all three treatments, hsa-miR-200b-3p was significantly upregulated. Functional enrichment analysis revealed that Hippo and FoxO signaling pathways were primarily impacted in AQP4-IgG + ve and double negative sera treated cells whereas, MOG-IgG + ve sera treatment perturbed the PI3K-Akt and MAPK signaling pathways. Furthermore, NGS also revealed differential expression of several piRNAs in cells upon treatment with AQP4-IgG + ve and MOG-IgG + ve sera and VEGF signaling was identified as the common target of differentially expressed piRNAs of both the groups. This study, for the first time, revealed that the molecular pathophysiology of double-seronegative NMOSD might involve astrocytopathy akin to AQP4+ve NMOSD, thus pointing towards the possible existence of unidentified astrocytic autoimmune targets and identified the major alterations in intracellular sncRNAs and the associated overall cellular signaling pathways that potentially contribute to the fate of astrocytes during the progression of the disease.

Antibodies in neurological diseases: Established, emerging, explorative

Within a few years, autoantibodies targeting the nervous system resulted in a novel disease classification. For several of them, which we termed 'established', direct pathogenicity has been proven and now guides diagnostic pathways and early immunotherapy. For a rapidly growing number of further anti-neuronal autoantibodies, the role in disease is less clear. Increasing evidence suggests that they could contribute to disease, by playing a modulating role on brain function. We therefore suggest a three-level classification of neurological autoantibodies according to the degree of experimentally proven pathogenicity and strength of clinical association: established, emerging, explorative. This may facilitate focusing on clinical constellations in which autoantibody-mediated mechanisms have not been assumed previously, including autoimmune psychosis and dementia, cognitive impairment in cancer, and neurodegenerative diseases. Based on recent data reviewed here, humoral autoimmunity may represent an additional "super-system" for brain health. The "brain antibody-ome", that is, the composition of thousands of anti-neuronal autoantibodies, may shape neuronal function not only in disease, but even in healthy aging. Towards this novel concept, extensive research will have to elucidate pathogenicity from the atomic to the clinical level, autoantibody by autoantibody. Such profiling can uncover novel biomarkers, enhance our understanding of underlying mechanisms, and identify selective therapies.

Blood-Brain Barrier Disruption in Neuroimmunological Disease

The blood-brain barrier (BBB) acts as a structural and functional barrier for brain homeostasis. This review highlights the pathological contribution of BBB dysfunction to neuroimmunological diseases, including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), autoimmune encephalitis (AE), and paraneoplastic neurological syndrome (PNS). The transmigration of massive lymphocytes across the BBB caused by the activation of cell adhesion molecules is involved in the early phase of MS, and dysfunction of the cortical BBB is associated with the atrophy of gray matter in the late phase of MS. At the onset of NMOSD, increased permeability of the BBB causes the entry of circulating AQP4 autoantibodies into the central nervous system (CNS). Recent reports have shown the importance of glucose-regulated protein (GRP) autoantibodies as BBB-reactive autoantibodies in NMOSD, which induce antibody-mediated BBB dysfunction. BBB breakdown has also been observed in MOGAD, NPSLE, and AE with anti-NMDAR antibodies. Our recent report demonstrated the presence of GRP78 autoantibodies in patients with MOGAD and the molecular mechanism responsible for GRP78 autoantibody-mediated BBB impairment. Disruption of the BBB may explain the symptoms in the brain and cerebellum in the development of PNS, as it induces the entry of pathogenic autoantibodies or lymphocytes into the CNS through autoimmunity against tumors in the periphery. GRP78 autoantibodies were detected in paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome, and they were associated with cerebellar ataxia with anti-P/Q type voltage-gated calcium channel antibodies. This review reports that therapies affecting the BBB that are currently available for disease-modifying therapies for neuroimmunological diseases have the potential to prevent BBB damage.

A Comprehensive Management of Devic's Disease: A Pediatric Case Study

Devic's disease, also known as neuromyelitis optica (NMO), is an uncommon autoimmune condition that affects the optic nerves and spinal cord. It is characterized by recurrent optic neuritis and myelitis, which can cause paralysis and visual impairment. Because NMO mimics multiple sclerosis, diagnosing it is difficult and necessitates particular testing, such as magnetic resonance imaging (MRI) and aquaporin-4 antibody detection. Patients with NMOs are susceptible to severe, erratic episodes that can result in rapid impairment. As such, timely and efficient therapy with immunosuppressive medicines and continued supportive care are crucial. Improving mobility, strength, coordination, and quality of life while treating the functional deficiencies associated with NMOs requires the use of physiotherapy. This case study emphasizes how crucial it is to manage a young NMO patient using a multidisciplinary strategy in order to maximise results. This case report discusses a 16-year-old male presenting with a sudden onset of balance impairment, slurred speech, difficulty walking and breathing, and weakness in limbs, with the right side more affected. Over three months, he experienced increasing eyesight issues, fatigue, tremors during activities of daily living, difficulty swallowing, and night cramps. Diagnostic investigations including MRI, angiography, visual evoked potentials (VEP) study, and cerebrospinal fluid (CSF) analysis confirmed demyelinating changes consistent with NMO, also known as Devic's disease. The patient received management with steroidal medications, immunosuppressants, and plasma therapy, along with physiotherapy rehabilitation. The physiotherapy protocol aimed to address muscle weakness, coordination impairment, balance issues, fine motor deficits, fatigue, sensory impairment, and dependence on activities of daily living. Motor, sensory, and cranial nerve assessments were conducted, revealing impairments consistent with NMO. Outcome measures pre- and post-intervention showed improvements in functional independence, balance, and fatigue severity. The medical management included a combination of medications and investigations to manage NMO symptoms and monitor disease progression. The physiotherapeutic approach employed a multidisciplinary strategy focusing on education, exercise, and functional tasks to improve the patient's quality of life and independence.

Intruders or protectors - the multifaceted role of B cells in CNS disorders

B lymphocytes are immune cells studied predominantly in the context of peripheral humoral immune responses against pathogens. Evidence has been accumulating in recent years on the diversity of immunomodulatory functions that B cells undertake, with particular relevance for pathologies of the central nervous system (CNS). This review summarizes current knowledge on B cell populations, localization, infiltration mechanisms, and function in the CNS and associated tissues. Acute and chronic neurodegenerative pathologies are examined in order to explore the complex, and sometimes conflicting, effects that B cells can have in each context, with implications for disease progression and treatment outcomes. Additional factors such as aging modulate the proportions and function of B cell subpopulations over time and are also discussed in the context of neuroinflammatory response and disease susceptibility. A better understanding of the multifactorial role of B cell populations in the CNS may ultimately lead to innovative therapeutic strategies for a variety of neurological conditions.

Optimizing the diagnostic performance of neural antibody testing for paraneoplastic and autoimmune encephalitis in clinical practice

The detection of neural antibodies in patients with paraneoplastic and autoimmune encephalitis has majorly advanced the diagnosis and management of neural antibody-associated diseases. Although testing for these antibodies has historically been restricted to specialized centers, assay commercialization has made this testing available to clinical chemistry laboratories worldwide. This improved test accessibility has led to reduced turnaround time and expedited diagnosis, which are beneficial to patient care. However, as the utilization of these assays has increased, so too has the need to evaluate how they perform in the clinical setting. In this chapter, we discuss assays for neural antibody detection that are in routine use, draw attention to their limitations and provide strategies to help clinicians and laboratorians overcome them, all with the aim of optimizing neural antibody testing for paraneoplastic and autoimmune encephalitis in clinical practice.

Methyl-CpG-Binding Protein 2 Emerges as a Central Player in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders

MECP2 and its product methyl-CpG binding protein 2 (MeCP2) are associated with multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD), which are inflammatory, autoimmune, and demyelinating disorders of the central nervous system (CNS). However, the mechanisms and pathways regulated by MeCP2 in immune activation in favor of MS and NMOSD are not fully understood. We summarize findings that use the binding properties of MeCP2 to identify its targets, particularly the genes recognized by MeCP2 and associated with several neurological disorders. MeCP2 regulates gene expression in neurons, immune cells and during development by modulating various mechanisms and pathways. Dysregulation of the MeCP2 signaling pathway has been associated with several disorders, including neurological and autoimmune diseases. A thorough understanding of the molecular mechanisms underlying MeCP2 function can provide new therapeutic strategies for these conditions. The nervous system is the primary system affected in MeCP2-associated disorders, and other systems may also contribute to MeCP2 action through its target genes. MeCP2 signaling pathways provide promise as potential therapeutic targets in progressive MS and NMOSD. MeCP2 not only increases susceptibility and induces anti-inflammatory responses in immune sites but also leads to a chronic increase in pro-inflammatory cytokines gene expression (IFN-γ, TNF-α, and IL-1β) and downregulates the genes involved in immune regulation (IL-10, FoxP3, and CX3CR1). MeCP2 may modulate similar mechanisms in different pathologies and suggest that treatments for MS and NMOSD disorders may be effective in treating related disorders. MeCP2 regulates gene expression in MS and NMOSD. However, dysregulation of the MeCP2 signaling pathway is implicated in these disorders. MeCP2 plays a role as a therapeutic target for MS and NMOSD and provides pathways and mechanisms that are modulated by MeCP2 in the regulation of gene expression.

Pathogenic role of autoantibodies at the ependyma in autoimmune disorders of the central nervous system

Ependymal cells make up the epithelial monolayer that lines the brain ventricles and the spinal cord central canal that are filled with cerebrospinal fluid. The ependyma has several functions, including regulating solute exchange between the cerebrospinal fluid and parenchyma, controlling microcirculation of cerebrospinal fluid via coordinated ciliary beating, and acting as a partial barrier. Dysregulation of these functions can lead to waste clearance impairment, cerebrospinal fluid accumulation, hydrocephalus, and more. A role for ependymal cells in a variety of neurological disorders has been proposed, including in neuromyelitis optica and multiple sclerosis, two autoimmune demyelinating diseases of the central nervous system, where periventricular damage is common. What is not known is the mechanisms behind how ependymal cells become dysregulated in these diseases. In neuromyelitis optica, it is well established that autoantibodies directed against Aquaporin-4 are drivers of disease, and it has been shown recently that these autoantibodies can drive ependymal cell dysregulation. We propose a similar mechanism is at play in multiple sclerosis, where autoantibodies targeting a glial cell protein called GlialCAM on ependymal cells are contributing to disease. GlialCAM shares high molecular similarities with the Epstein-Barr virus (EBV) protein EBNA1. EBV has recently been shown to be necessary for multiple sclerosis initiation, yet how EBV mediates pathogenesis, especially in the periventricular area, remains elusive. In this perspective article, we discuss how ependymal cells could be targeted by antibody-related autoimmune mechanisms in autoimmune demyelinating diseases and how this is implicated in ventricular/periventricular pathology.

Research progress on pathogenesis and clinical treatment of neuromyelitis optica spectrum disorders (NMOSDs)

Neuromyelitis optica spectrum disorders (NMOSDs) are characteristically referred to as various central nervous system (CNS)-based inflammatory and astrocytopathic disorders, often manifested by the axonal damage and immune-mediated demyelination targeting optic nerves and the spinal cord. This review article presents a detailed view of the etiology, pathogenesis, and prescribed treatment options for NMOSD therapy. Initially, we present the epidemiology of NMOSDs, highlighting the geographical and ethnical differences in the incidence and prevalence rates of NMOSDs. Further, the etiology and pathogenesis of NMOSDs are emphasized, providing discussions relevant to various genetic, environmental, and immune-related factors. Finally, the applied treatment strategies for curing NMOSD are discussed, exploring the perspectives for developing emergent innovative treatment strategies.

Neuromyelitis Optica Spectrum Disorder Mimicking Pontine Stroke: A Case Report and Systematic Literature Review

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disorder that was first described in the late 1800s as a variant of multiple sclerosis (MS). However, it has recently been categorized, as a disease, especially with the discovery of aquaporin-4 (AQP4-Ab) and myelin oligodendrocyte glycoprotein antibodies (MOG-Ab). Unfortunately, patient presentation is not always clear, and NMOSD may initially be diagnosed as an alternative neurological disease. We present a 58-year-old woman who was hospitalized several times for what was initially perceived as a pontine stroke. However, given worsening symptoms, serologic testing confirmed AQP4-Ab positivity and, subsequently, the NMOSD diagnosis. In addition to the case report, a systematic literature review was performed to identify NMOSD cases initially misdiagnosed as stroke. Publications were selected and curated in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six NMOSD patients were initially thought to have had acute strokes. However, steady progression and/or the recurrence of symptoms suggested that further investigations with neuroimaging studies and serological immune assays were necessary to exclude alternative etiologies. Notably, the age at onset in all cases was significantly more advanced than patients with typical NMOSD presentations (median age 32-41). In conclusion, the NMOSD diagnosis should be considered in cases with atypical stroke-like presentations, particularly those of later onset (defined as equal to or greater than 50 years of age). This is important as early recognition and treatment with immune therapies can improve functional outcomes.

Update on the diagnosis and treatment of neuromyelits optica spectrum disorders (NMOSD) - revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part I: Diagnosis and differential diagnosis

The term 'neuromyelitis optica spectrum disorders' (NMOSD) is used as an umbrella term that refers to aquaporin-4 immunoglobulin G (AQP4-IgG)-positive neuromyelitis optica (NMO) and its formes frustes and to a number of closely related clinical syndromes without AQP4-IgG. NMOSD were originally considered subvariants of multiple sclerosis (MS) but are now widely recognized as disorders in their own right that are distinct from MS with regard to immunopathogenesis, clinical presentation, optimum treatment, and prognosis. In part 1 of this two-part article series, which ties in with our 2014 recommendations, the neuromyelitis optica study group (NEMOS) gives updated recommendations on the diagnosis and differential diagnosis of NMOSD. A key focus is on differentiating NMOSD from MS and from myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis (MOG-EM; also termed MOG antibody-associated disease, MOGAD), which shares significant similarity with NMOSD with regard to clinical and, partly, radiological presentation, but is a pathogenetically distinct disease. In part 2, we provide updated recommendations on the treatment of NMOSD, covering all newly approved drugs as well as established treatment options.

miR-211-5p targeting MMP9 regulates the expressions of AQP4 in traumatic brain injury

OBJECTIVE

The abnormal expression of matrix metalloproteinase 9 (MMP9) and Aquaporin 4 (AQP4) closely associates with the traumatic brain injury (TBI) development.

METHODS

Here, we investigated the relationship between miR-211-5p and MMP9/AQP4 axis in TBI patients and astrocyte cells. Demographics, clinical features, and cerebrospinal fluid (CSF) samples were collected from traumatic brain injury (TBI) patients (n = 96) and controls (n = 30) for pathological and gene expression analyses. Luciferase activity assay and gene expression analyses were performed to dissect the regulatory mechanism of miR-211-5p on MMP9/AQP4 in human astrocyte cells.

RESULTS

miR-211-5p mRNA was significantly decreased in the CSF of TBI patients, which positively correlated with the expression of both MMP9 and AQP4. miR-211-5p could target MMP9 directly in SVG P12 cells. Overexpression of miR-211-5p decreased the expression of MMP9, on the contrary, knockdown miR-211-5p through inhibitors increased the expression of both MMP9 and AQP4.

CONCLUSION

miR-211-5p inhibits the MMP9/AQP4 axis in human astrocyte cells, which represents a promising approach for the TBI treatment.

Conus medullaris syndrome as a presenting feature of MOG-associated disease

We report a case of conus medullaris syndrome presenting with lower limb and bladder symptoms. MR imaging showed an abnormality in the lowest part of the spinal cord as a first presentation of myelin oligodendrocyte glycoprotein (MOG)-associated disease. While such cord swelling can mimic a tumour, these patients respond well to corticosteroids, with good outcomes. MOG-associated disease is an immune-mediated syndrome distinct from aquaporin 4 antibody positive neuromyelitis optica syndrome and is now considered an independent entity. Although there can be overlapping phenotypes, there are also differences, and MOG-associated disease generally has a much better prognosis compared with aquaporin 4 antibody-positive neuromyelitis optica syndrome.

Neuromyelitis optica: Clinical course and potential prognostic indicators

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune neurological disorder associated with antibodies to aquaporin-4 (AQP4). NMOSD has been thought to follow a progressive disease course, with step-wise accumulation of disability over time, even in patients undergoing immunosuppressive/immunomodulatory therapy. The influence of factors such as AQP4 seropositivity, AQP4 serum titer levels, and administration of plasmapheresis on NMOSD prognosis is, as yet, unclear.

METHODS

We performed a retrospective chart review of 53 persons with NMOSD at Duke University Hospital-collecting data on longitudinal disease course, imaging, demographics, and serum AQP4 titers (measured using the ELISA or FACS method). Most patients in our cohort were treated with high-dose corticosteroids and, following diagnosis, received maintenance immunosuppressive/immunomodulatory therapies. Longitudinal data on EDSS scores were used to calculate the slope of disability over time for each participant. We additionally investigated the correlation between initial AQP4 seropositivity, initial AQP4 serum titer levels, and treatment with plasmapheresis on disability progression for each participant.

RESULTS

Contrary to current views on NMOSD disease course, the majority of our participants showed either no change (31.9%) or improvement (27.1%) in disability over time. Our results additionally revealed no significant association between clinical prognosis and initial AQP4 seropositivity (p = 0.830), initial AQP4 serum titer levels (p = 0.338), or administration of plasmapheresis (p = 0.1149).

CONCLUSIONS

Our study presents a contemporary view of the clinical course of NMOSD and shows a more favorable view of its disease course than prior studies (performed before high-efficacy disease modifying therapies became widely-used for this patient population). Most patients in this study received treatment with high-dose corticosteroids following NMOSD flares, as well as a variety of maintenance immunosuppressive therapies. The results of this study cannot shed light on the disease course of untreated NMOSD. Our findings additionally challenge the theory that AQP4 seropositivity or serum titer levels at time of diagnosis may be used to effectively predict NMOSD prognosis. While we were unable to find evidence supporting a favorable effect of plasmapheresis administration on disease outcomes, further research is needed to determine the role plasmapheresis ought to play in the treatment of NMOSD.

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.

Diagnostik der Neuromyelitis-optica-Spektrum-Erkrankung (NMOSD) und der MOG-Antikörper-assoziierten Erkrankung (MOGAD)

Die Aquaporin-4-Antikörper-positive Neuromyelitis-optica-Spektrum-Erkrankung (engl. NMOSD) und die Myelin-Oligodendrozyten-Glykoprotein-Antikörper-assoziierte Erkrankung (engl. MOGAD) sind Autoimmunerkrankungen des zentralen Nervensystems. Typische Erstmanifestationen sind bei Erwachsenen Optikusneuritis und Myelitis. Eine Beteiligung auch von Hirn und Hirnstamm, spätestens im weiteren Verlauf, ist häufig. Während die NMOSD nahezu immer schubförmig verläuft, nimmt die MOGAD gelegentlich einen monophasischen Verlauf. Die Differenzialdiagnostik ist anspruchsvoll und stützt sich auf u. a. auf radiologische und serologische Befunde. Die Abgrenzung von der häufigeren neuroinflammatorischen Erkrankung, Multiple Sklerose (MS), ist von erheblicher Bedeutung, da sich Behandlung und langfristige Prognose von NMOSD, MOGAD und MS wesentlich unterscheiden. Die vielfältigen Symptome und die umfangreiche Diagnostik machen eine enge Zusammenarbeit zwischen Ophthalmologie, Neurologie und Radiologie erforderlich. Dieser Artikel gibt einen Überblick über typische MRT-Befunde und die serologische Antikörperdiagnostik bei NMOSD und MOGAD. Zwei illustrative Fallberichte aus der ärztlichen Praxis ergänzen die Darstellung.

Serum levels of interleukin-6 and Vitamin D at the onset of multiple sclerosis and neuromyelitis optica: A pilot study

BACKGROUND

Interleukin-6 (IL-6) is an important mediator in the acute phase of inflammatory diseases such as neuromyelitis optica (NMO) and multiple sclerosis (MS). The level of IL-6 is higher in cerebrospinal fluid and serum of NMO patients compare to MS. Vitamin D has a regulatory effect on IL-6, so it may have a negative correlation with IL-6 in the acute phase of these diseases. This study was performed to evaluate the serum levels of IL-6 and Vitamin D in NMO and MS patients at the onset of disease to find differences that may help in early diagnosis.

MATERIALS AND METHODS

This case-control study was done on patients with the first episode of optic neuritis, transverse myelitis, and area postrema syndrome who were referred to Kashani MS Center in Isfahan, Iran, between January 2018 and January 2020. The serum levels of Vitamin D and IL-6 were assessed using enzyme-linked immunosorbent assay in blood sample taken at the time of first presentation in patients who had a definitive diagnosis of NMO and MS during subsequent workup.

RESULTS

During a 2-year follow-up, definitive diagnosis of NMO was given in 25 cases, and they were compared with 25 cases that were randomly selected from patients with definite MS. Nineteen patients in the NMO group and 21 patients in the MS group were female. The mean age of patients in the NMO and MS groups was 29.64 ± 1.47 and 30.20 ± 1.42, respectively (P = 0.46). The mean of serum level of Vitamin D was 24.88 ± 15.2 in NMO patients and 21.56 ± 18.7 in MS patients without significant difference (P = 0.48). The mean of IL-6 was 30.1 ± 22.62 in the NMO group and 23.35 ± 18.8 in the MS group without significant difference (P = 0.28). The serum levels of Vitamin D were insufficient in both groups. No correlation between Vitamin D and IL-6 levels was found in our study (P > 0.05).

CONCLUSION

Our results showed that serum IL-6 levels were higher at the onset of NMO disease compared with MS. The serum levels of Vitamin D were low in both groups and there was no association between serum levels of Vitamin D and IL-6 in either group. Future studies with large sample size are needed to confirm these findings.

Genetics behind Cerebral Disease with Ocular Comorbidity: Finding Parallels between the Brain and Eye Molecular Pathology

Cerebral visual impairments (CVIs) is an umbrella term that categorizes miscellaneous visual defects with parallel genetic brain disorders. While the manifestations of CVIs are diverse and ambiguous, molecular diagnostics stand out as a powerful approach for understanding pathomechanisms in CVIs. Nevertheless, the characterization of CVI disease cohorts has been fragmented and lacks integration. By revisiting the genome-wide and phenome-wide association studies (GWAS and PheWAS), we clustered a handful of renowned CVIs into five ontology groups, namely ciliopathies (Joubert syndrome, Bardet-Biedl syndrome, Alstrom syndrome), demyelination diseases (multiple sclerosis, Alexander disease, Pelizaeus-Merzbacher disease), transcriptional deregulation diseases (Mowat-Wilson disease, Pitt-Hopkins disease, Rett syndrome, Cockayne syndrome, X-linked alpha-thalassaemia mental retardation), compromised peroxisome disorders (Zellweger spectrum disorder, Refsum disease), and channelopathies (neuromyelitis optica spectrum disorder), and reviewed several mutation hotspots currently found to be associated with the CVIs. Moreover, we discussed the common manifestations in the brain and the eye, and collated animal study findings to discuss plausible gene editing strategies for future CVI correction.

Testing for Antibodies Against Aquaporin-4 and Myelin Oligodendrocyte Glycoprotein in the Diagnosis of Patients With Suspected Autoimmune Myelopathy

Autoimmune myelopathies are immune-mediated disorders of the spinal cord that can cause significant neurologic disability. Discoveries of antibodies targeting aquaporin-4 (AQP4-IgG) and myelin oligodendrocyte glycoprotein (MOG-IgG) have facilitated the diagnosis of autoimmune myelopathies that were previously considered to be atypical presentations of multiple sclerosis (MS) or idiopathic, and represent major advancements in the field of autoimmune neurology. The detection of these antibodies can substantially impact patient diagnosis and management, and increasing awareness of this has led to a dramatic increase in testing for these antibodies among patients with suspected autoimmune myelopathy. In this review we discuss test methodologies used to detect these antibodies, the role of serum vs. cerebrospinal fluid testing, and the value of antibody titers when interpreting results, with the aim of helping laboratorians and clinicians navigate this testing when ordered as part of the diagnostic evaluation for suspected autoimmune myelopathy.

Evolution of Anti-B Cell Therapeutics in Autoimmune Neurological Diseases

B cells have an ever-increasing role in the etiopathology of a number of autoimmune neurological disorders, acting as antigen-presenting cells facilitating antibody production but also as sensors, coordinators, and regulators of the immune response. In particular, B cells can regulate the T cell activation process through their participation in antigen presentation, production of proinflammatory cytokines (bystander activation or suppression), and contribution to ectopic lymphoid aggregates. Such an important interplay between B and T cells makes therapeutic depletion of B cells an attractive treatment strategy. The last decade, anti-B cell therapies using monoclonal antibodies against B cell surface molecules have evolved into a rational approach for successfully treating autoimmune neurological disorders, even when T cells seem to be the main effector cells. The paper summarizes basic aspects of B cell biology, discusses the roles of B cells in neurological autoimmunities, and highlights how the currently available or under development anti-B cell therapeutics exert their action in the wide spectrum and immunologically diverse neurological disorders. The efficacy of the various anti-B cell therapies and practical issues on induction and maintenance therapy is specifically detailed for the treatment of patients with multiple sclerosis, neuromyelitis-spectrum disorders, autoimmune encephalitis and hyperexcitability CNS disorders, autoimmune neuropathies, myasthenia gravis, and inflammatory myopathies. The success of anti-B cell therapies in inducing long-term remission in IgG4 neuroautoimmunities is also highlighted pointing out potential biomarkers for follow-up infusions.

Unraveling autoimmune and neurodegenerative diseases by amperometric serological detection of antibodies against aquaporin-4

This work reports the first electroanalytical bioplatform to date for the determination of antibodies against aquaporin-4 (AQP4-Abs), whose serum level is considered as relevant biomarker for certain autoimmune diseases. The bioplatform relies on the use of magnetic microparticles modified with the biotinylated protein for the capture of specific antibodies. The captured IgGs are enzymatically labelled with a secondary antibody conjugated to the horseradish peroxidase (HRP) enzyme. Amperometric transduction is performed using the H2O2/hydroquinone (HQ) system, which results in a cathodic current variation directly proportional to the concentration of the target antibodies. The evaluation of the analytical and operational characteristics of the developed bioplatform shows that it is competitive in terms of sensitivity with the only biosensor reported to date as well as with the commercially available ELISA kits. The achieved limit of detection value is 8.8 pg mL-1. In addition, compared to ELISA kits, the developed bioplatform is advantageous in terms of cost and point of care operation ability. The bioplatform was applied to the analysis of control serum samples with known AQP4-Abs contents as well as of sera from healthy individuals and patients diagnosed with Systemic Lupus Erythematosus (SLE) and Alzheimer (AD) diseases, providing results in agreement with the ELISA methodology.

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.

RGMa signal in Macrophages Induces Neutrophil-related Astrocytopathy in NMO

OBJECTIVE

Repulsive guidance molecule-a (RGMa) is a glycosylphosphatidylinositol-linked glycoprotein which has multiple functions including axon growth inhibition and immune regulation. However, its role in the pathophysiology of neuromyelitis optica (NMO) is poorly understood. Perivascular astrocytopathy, which is induced by the leakage of aquaporin-4 (AQP4)-specific IgG into the central nervous system parenchyma, is a key feature of NMO pathology. We investigated the RGMa involvement in the pathology of NMO astrocytopathy, and tested a therapeutic potential of humanized anti-RGMa monoclonal antibody (RGMa-mAb).

METHODS

Using a clinically relevant NMO rat model, we evaluated the therapeutic effect of a RGMa-mAb by behavioral testing, immunohistochemistry, and gene expression assay. We further performed in vitro experiments to address the RGMa-signaling in macrophages.

RESULTS

In both NMO rats and an NMO-autopsied sample, RGMa was expressed by the spared neurons and astrocytes, whereas its receptor neogenin was expressed by infiltrating macrophages. AQP4-IgG-induced astrocytopathy and clinical exacerbation in NMO rats were ameliorated by RGMa-mAb treatment. RGMa-mAb treatment significantly suppressed neutrophil infiltration, and decreased the expression of neutrophil chemoattractants. Interestingly, neogenin-expressing macrophages accumulated in the lesion expressed CXCL2, a strong neutrophil chemoattractant, and further analysis revealed that RGMa directly regulated CXCL2 expression in macrophages. Finally, we found that our NMO rats developed neuropathic pain, and RGMa-mAb treatment effectively ameliorated the severity of neuropathic pain.

INTERPRETATION

RGMa signaling in infiltrated macrophages is a critical driver of neutrophil-related astrocytopathy in NMO lesions, and RGMa-mAb may provide an efficient therapeutic strategy for NMO-associated neuropathic pain and motor deficits in patients with NMO. This article is protected by copyright. All rights reserved.

Myelin Oligodendrocyte Glycoprotein-Immunoglobulin G in the CSF: Clinical Implication of Testing and Association With Disability

BACKGROUND AND OBJECTIVE

To investigate the clinical relevance of CSF myelin oligodendrocyte glycoprotein-immunoglobulin G (MOG-IgG) testing in a large multicenter cohort.

METHODS

In this multicenter cohort study, paired serum-CSF samples from 474 patients with suspected inflammatory demyelinating disease (IDD) from 11 referral hospitals were included. After serum screening, patients were grouped into seropositive myelin oligodendrocyte glycoprotein antibody associated disease (MOGAD, 31), aquaporin-4-IgG-positive neuromyelitis optica spectrum disorder (AQP4-IgG + NMOSD, 60), other IDDs (217), multiple sclerosis (MS, 45), and non-IDDs (121). We then screened CSF for MOG-IgG and compared the clinical and serologic characteristics of patients uniquely positive for MOG-IgG in the CSF to seropositive patients with MOGAD.

RESULTS

Nineteen patients with seropositive MOGAD (61.3%), 9 with other IDDs (CSF MOG + IDD, 4.1%), 4 with MS (8.9%), but none with AQP4-IgG + NMOSD nor with non-IDDs tested positive in the CSF for MOG-IgG. The clinical, pathologic, and prognostic features of patients uniquely positive for CSF MOG-IgG, with a non-MS phenotype, were comparable with those of seropositive MOGAD. Intrathecal MOG-IgG synthesis, observed from the onset of disease, was shown in 12 patients: 4 of 28 who were seropositive and 8 who were uniquely CSF positive, all of whom had involvement of either brain or spinal cord. Both CSF MOG-IgG titer and corrected CSF/serum MOG-IgG index, but not serum MOG-IgG titer, were associated with disability, CSF pleocytosis, and level of CSF proteins.

DISCUSSION

CSF MOG-IgG is found in IDD other than MS and also in MS. In IDD other than MS, the CSF MOG-IgG positivity can support the diagnosis of MOGAD. The synthesis of MOG-IgG in the CNS of patients with MOGAD can be detected from the onset of the disease and is associated with the severity of the disease.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that the presence of CSF MOG-IgG can improve the diagnosis of MOGAD in the absence of an MS phenotype, and intrathecal synthesis of MOG-IgG was associated with increased disability.

Serum Aquaporin 4-Immunoglobulin G Titer and Neuromyelitis Optica Spectrum Disorder Activity and Severity: A Systematic Review and Meta-Analysis

Background: Aquaporin 4-immunoglobulin G (AQP4-IgG) plays a major role in the pathogenesis of neuromyelitis optica spectrum disorder (NMOSD). Seropositive status for this antibody has become one of the required indicators for NMOSD diagnosis. Objective: Our goal was to systematically review and perform a meta-analysis of the current works of literature evaluating the clinical relevance of serum AQP4-IgG titer in patients with NMOSD. We sought to determine whether AQP4-IgG could indicate disease activity or severity, in addition to its diagnostic value in NMOSD. Methods: Electronic databases were searched for published literature, yielding 4,402 hits. Of the 124 full articles screened, 17 were included in the qualitative analysis and 14 in the meta-analysis. Results: There were no significant differences in serum AQP4-IgG titers between the relapse and remission phases in patients with NMOSD [standard mean difference (SMD): 0.32, 95% CI (-0.10, 0.74), p = 0.14]. Subgroup meta-analysis of AQP4-IgG detected by cell-based assays (CBA), an AQP4-IgG testing method recommended by the 2015 international consensus diagnostic criteria for NMOSD, confirmed the aforementioned result [SMD: 0.27, 95% CI (-0.01, 0.55), p = 0.06]. Moreover, the serum AQP4-IgG titer was positively correlated with the number of involved spinal cord segments [correlation coefficient (COR): 0.70, 95% CI (0.28-0.89), p = 0.003] and the Expanded Disability Status Scale (EDSS) score [COR: 0.54, 95% CI (0.06-0.82), p = 0.03] in the attack phase in patients with NMOSD. Conclusions: The present study systematically assessed the association between serum AQP4-IgG titer and NMOSD activity and severity. The results demonstrated that the serum AQP4-IgG titer was not associated with disease activity but indicated the disease severity in the attack phase in patients with NMOSD. A further meta-analysis with a larger number of studies that employed standardized AQP4-IgG assays and detected attack-remission paired samples from the same patients with detailed medication information will be required to confirm our findings and shed more light on optimizing clinical AQP4-IgG monitoring. Systematic Review Registration: [www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=208209], PROSPERO, identifier [CRD42020208209].

AQP4-IgG positive paraneoplastic NMOSD: A case report and review

INTRODUCTION

Neuromyelitis optica spectrum disorder (NMOSD; also known as Devic syndrome) is a clinical syndrome of central nervous system characterized by immune mediated attacks of acute optic neuritis and myelitis. Paraneoplastic neurological syndrome is a group of nervous system disorders resulting from the remote immune effects of malignant neoplasm. NMOSD occurs mostly in young people, and tumor is not a common cause, especially recurrent tumor.

METHODS

We reported a case of a 59-year-old man who developed anti-aquaporin-4 IgG positive longitudinally extensive myelitis. We also summarized and analyzed previously reported cases of paraneoplastic NMOSD.

RESULTS

Among these 43 patients, 88.4% patients are female. The largest number of patients is between 60 and 69 years old. Breast cancer and lung cancer are the most common types. The most common lesions were located in the cervicothoracic region with patchy gadolinium enhancement. The existing treatment can only delay rather than stop the progress of the disease.

CONCLUSION

It is necessary to perform tumor screening in patients with NMOSD, especially patients over 50 years.

Longitudinally extensive transverse myelitis with positive aquaporin-4 IgG associated with dengue infection: a case report and systematic review of cases

BACKGROUND

Neuromyelitis Optica Spectrum Disorder can be associated with parainfectious and post-infectious triggers. Dengue virus infection is one of the most common arbovirus infections in the world, and may present with neurological manifestations.

OBJECTIVES

We present a case of DENV-associated with LETM and positive aquaporin-4 IgG, and a systematic review of published cases.

METHODS

Medline (Ovid) and PubMed were search through June 2021, for case reports, series and observational studies that described patients with DENV-associated LETM and/or NMOSD.

RESULTS

An adolescent girl who had recently immigrated from a Dengue-endemic region presented with a LETM with high positive AQP4-IgG titer and seropositive DENV IgM/IgG antibodies. She responded well to steroids and subsequently started maintenance rituximab for her NMOSD diagnosis.

LITERATURE REVIEW

22 publications describing 27 patients met inclusion criteria. In addition to this case, three published cases met current criteria for NMOSD with serological evidence of acute DENV infection.

CONCLUSIONS

It is unknown whether there is a pathophysiological association between DENV infection and NMOSD. Regardless, if an immune-mediated event is suspected, particularly NMOSD, appropriate immunotherapy should be considered early. Decision regarding long term immunotherapy may depend on index of suspicion of true NMOSD, and this is where AQP4-IgG status and follow-up is helpful.

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.

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

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

Difference in the Source of Anti-AQP4-IgG and Anti-MOG-IgG Antibodies in CSF in Patients With Neuromyelitis Optica Spectrum Disorder

Objective

To elucidate the differences in the source and in the level of intrathecal synthesis between anti–aquaporin-4 antibodies (AQP4-IgG) and anti-myelin oligodendrocyte glycoprotein antibodies (MOG-IgG).

Methods

Thirty-eight patients with MOG-IgG–associated disease and 36 with AQP4-IgG–positive neuromyelitis optica spectrum disorders (NMOSD) were studied for the antibody titers in the sera and CSF simultaneously collected in the acute attacks. The quotients between CSF and serum levels of albumin, total immunoglobulin G, and each disease-specific antibody were calculated. Intrathecal production level in each disease-specific antibody was evaluated by calculating the antibody index from these quotients.

Results

Eleven of the 38 patients with MOG-IgG were positive for the antibody only in the CSF, while no patient with AQP4-IgG showed CSF-restricted AQP4-IgG. Blood-brain barrier compromise as shown by raised albumin quotients was seen in 75.0% of MOG-IgG–positive cases and 43.8% of AQP4-IgG–positive cases. Moreover, MOG-IgG quotients were >10 times higher than AQP4-IgG quotients (effect size r = 0.659, p < 0.0001). Elevated antibody index (>4.0) was confirmed in 12 of 21 with MOG-IgG, whereas it was seen only in 1 of 16 with AQP4-IgG (φ = 0.528, p < 0.0001). The CSF MOG-IgG titers (ρ = 0.519, p = 0.001) and antibody indexes for MOG-IgG (ρ = 0.472, p = 0.036) correlated with the CSF cell counts but not with clinical disability.

Conclusions

Intrathecal production of MOG-IgG may occur more frequently than that of AQP4-IgG. This finding implies the different properties of B-cell trafficking and antibody production between MOG-IgG–associated disease and AQP4-IgG–positive NMOSD.

Correlations among disability, anti-AQP4 antibody status and prognosis in the spinal cord involved patients with NMOSD

Background

Neuromyelitis optica spectrum disorder (NMOSD) is a rare neuroinflammatory disorder of the central nervous system that typically involves the optic nerve, the spinal cord and other specific brain regions. In relapse of the disease, factors associated with clinical features and lesion severity are important for clinicians to predict disease-related disability.

Methods

We retrospectively analyzed 22 female patients with NMOSD who had spinal cord lesions. Detailed clinical features, onset symptoms, motor disability, relapse episodes, serum aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) autoantibodies and MRI characteristics were documented to correlate their associations with the nadir and three-month Expanded Disability Status Scale (EDSS) scores. Patients with three-month EDSS scores below four (< 4) were categorized as the good outcome group, while those with scores of four or more (> 4) were categorized as the poor outcome group.

Results

In patients with NMOSD, the mean age was 44.5 ± 12.8 years, and the mean three-month EDSS score was 4.3 ± 1.9. A significantly higher all-limb muscle power score was found in the good EDSS group than in the poor EDSS group (p = 0.01). A tendency toward longer follow-up periods and lower anti-AQP4 antibody levels was found in the good outcome group. Serum anti-AQP4 antibodies were present in 86% of patients with NMOSD, and MOG autoantibodies were found in one anti-AQP4 antibody-negative patient (33.3%). In patients with NMOSD, more than 40% of spinal cord lesions were distributed at the middle cervical and upper thoracic levels.

Conclusions

Our findings suggest that EDSS scores and MRC scores at the nadir had significant associations with three-month EDSS scores. The topographic distributions of the spinal cord lesions might relate to different serum anti-AQP4 antibody status. However, further studies will be needed to corroborate this finding.

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

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

Neuromyelitis optica spectrum disorders

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

Neuromyelitis optica

Neuromyelitis optica (NMO; also known as Devic syndrome) is a clinical syndrome characterized by attacks of acute optic neuritis and transverse myelitis. In most patients, NMO is caused by pathogenetic serum IgG autoantibodies to aquaporin 4 (AQP4), the most abundant water-channel protein in the central nervous system. In a subset of patients negative for AQP4-IgG, pathogenetic serum IgG antibodies to myelin oligodendrocyte glycoprotein, an antigen in the outer myelin sheath of central nervous system neurons, are present. Other causes of NMO (such as paraneoplastic disorders and neurosarcoidosis) are rare. NMO was previously associated with a poor prognosis; however, treatment with steroids and plasma exchange for acute attacks and with immunosuppressants (in particular, B cell-depleting agents) for attack prevention has greatly improved the long-term outcomes. Recently, a number of randomized controlled trials have been completed and the first drugs, all therapeutic monoclonal antibodies, have been approved for the treatment of AQP4-IgG-positive NMO and its formes frustes.

NMOSD acute attack: Understanding, treatment and innovative treatment prospect

Neuromyelitis optica spectrum disorder (NMOSD) is a group of severe inflammatory demyelinating disorders of the central nervous system that involves the optic nerve and spinal cord. Currently the therapeutic options for an acute attack in NMOSD are limited and rarely characterized in clinical studies. This review discussed the overall characteristics of acute attack of NMOSD, related risk factor, prognosis and management. Considering the huge unmet needs and the emergence of new therapeutic targets, we also reviewed innovative treatments that might alleviate attack damage, along with the challenges to evaluate new drug for acute attack in NMOSD.

Cerebrospinal fluid findings in patients with myelin oligodendrocyte glycoprotein (MOG) antibodies. Part 1: Results from 163 lumbar punctures in 100 adult patients

BACKGROUND

New-generation cell-based assays have demonstrated a robust association of serum autoantibodies to full-length human myelin oligodendrocyte glycoprotein (MOG-IgG) with (mostly recurrent) optic neuritis, myelitis, and brainstem encephalitis, as well as with neuromyelitis optica (NMO)-like or acute-disseminated encephalomyelitis (ADEM)-like presentations. However, only limited data are yet available on cerebrospinal fluid (CSF) findings in MOG-IgG-associated encephalomyelitis (MOG-EM; also termed MOG antibody-associated disease, MOGAD).

OBJECTIVE

To describe systematically the CSF profile in MOG-EM.

MATERIAL AND METHODS

Cytological and biochemical findings (including white cell counts and differentiation; frequency and patterns of oligoclonal bands; IgG/IgM/IgA and albumin concentrations and CSF/serum ratios; intrathecal IgG/IgA/IgM fractions; locally produced IgG/IgM/IgA concentrations; immunoglobulin class patterns; IgG/IgA/IgM reibergrams; Link index; measles/rubella/zoster (MRZ) reaction; other anti-viral and anti-bacterial antibody indices; CSF total protein; CSF L-lactate) from 163 lumbar punctures in 100 adult patients of mainly Caucasian descent with MOG-EM were analyzed retrospectively.

RESULTS

Most strikingly, CSF-restricted oligoclonal IgG bands, a hallmark of multiple sclerosis (MS), were absent in almost 90% of samples (N = 151), and the MRZ reaction, the most specific laboratory marker of MS known so far, in 100% (N = 62). If present, intrathecal IgG (and, more rarely, IgM) synthesis was low, often transient and mostly restricted to acute attacks. CSF WCC was elevated in > 50% of samples (median 31 cells/μl; mostly lymphocytes and monocytes; > 100/μl in 12%). Neutrophils were present in > 40% of samples; activated lymphocytes were found less frequently and eosinophils and/or plasma cells only very rarely (< 4%). Blood-CSF barrier dysfunction (as indicated by an elevated albumin CSF/serum ratio) was present in 48% of all samples and at least once in 55% of all patients (N = 88) tested. The frequency and degree of CSF alterations were significantly higher in patients with acute myelitis than in patients with acute ON and varied strongly depending on attack severity. CSF L-lactate levels correlated significantly with the spinal cord lesion load in patients with acute myelitis (p < 0.0001). Like pleocytosis, blood-CSF barrier dysfunction was present also during remission in a substantial number of patients.

CONCLUSION

MOG-IgG-positive EM is characterized by CSF features that are distinct from those in MS. Our findings are important for the differential diagnosis of MS and MOG-EM and add to the understanding of the immunopathogenesis of this newly described autoimmune disease.

Cerebrospinal fluid findings in patients with myelin oligodendrocyte glycoprotein (MOG) antibodies. Part 2: Results from 108 lumbar punctures in 80 pediatric patients

BACKGROUND

New-generation, cell-based assays have demonstrated a robust association of serum autoantibodies to full-length human myelin oligodendrocyte glycoprotein (MOG-IgG) with (mostly recurrent) optic neuritis, myelitis, and brainstem encephalitis, as well as with neuromyelitis optica (NMO)-like or acute-disseminated encephalomyelitis (ADEM)-like presentations. However, only limited data are yet available on cerebrospinal fluid (CSF) findings in MOG-IgG-associated encephalomyelitis (MOG-EM; also termed MOG antibody-associated disease, MOGAD).

OBJECTIVE

To describe systematically the CSF profile in children with MOG-EM.

MATERIAL AND METHODS

Cytological and biochemical findings (including white cell counts [WCC] and differentiation; frequency and patterns of oligoclonal bands; IgG/IgM/IgA and albumin concentrations and CSF/serum ratios; intrathecal IgG/IgM/IgA fractions; locally produced IgG/IgM/IgA concentrations; immunoglobulin class patterns; IgG/IgA/IgM reibergrams; Link index; measles/rubella/zoster [MRZ] reaction; other anti-viral and anti-bacterial antibody indices; CSF total protein; CSF L-lactate) from 108 lumbar punctures in 80 pediatric patients of mainly Caucasian descent with MOG-EM were analyzed retrospectively.

RESULTS

Most strikingly, CSF-restricted oligoclonal IgG bands, a hallmark of multiple sclerosis (MS), were absent in 89% of samples (N = 96), and the MRZ reaction, the most specific laboratory marker of MS known so far, in 100% (N = 29). If present at all, intrathecal IgG synthesis was low, often transient and mostly restricted to acute attacks. Intrathecal IgM synthesis was present in 21% and exclusively detectable during acute attacks. CSF WCC were elevated in 54% of samples (median 40 cells/μl; range 6-256; mostly lymphocytes and monocytes; > 100/μl in 11%). Neutrophils were present in 71% of samples; eosinophils, activated lymphocytes, and plasma cells were seen only rarely (all < 7%). Blood-CSF barrier dysfunction (as indicated by an elevated albumin CSF/serum ratio) was present in 46% of all samples (N = 79) and at least once in 48% of all patients (N = 67) tested. CSF alterations were significantly more frequent and/or more pronounced in patients with acute spinal cord or brain disease than in patients with acute ON and varied strongly depending on attack severity. CSF L-lactate levels correlated significantly with the spinal cord lesions load (measured in vertebral segments) in patients with acute myelitis (p = 0.0099). An analysis of pooled data from the pediatric and the adult cohort showed a significant relationship of QAlb (p < 0.0005), CST TP (p < 0.0001), and CSF L-lactate (p < 0.0003) during acute attacks with age.

CONCLUSION

MOG-IgG-associated EM in children is characterized by CSF features that are distinct from those in MS. With regard to most parameters, no marked differences between the pediatric cohort and the adult cohort analyzed in Part 1 were noted. Our findings are important for the differential diagnosis of pediatric MS and MOG-EM and add to the understanding of the immunopathogenesis of this newly described autoimmune disease.

The B cell immunobiology that underlies CNS autoantibody-mediated diseases

A rapidly expanding and clinically distinct group of CNS diseases are caused by pathogenic autoantibodies that target neuroglial surface proteins. Despite immunotherapy, patients with these neuroglial surface autoantibody (NSAb)-mediated diseases often experience clinical relapse, high rates of long-term morbidity and adverse effects from the available medications. Fundamentally, the autoantigen-specific B cell lineage leads to production of the pathogenic autoantibodies. These autoantigen-specific B cells have been consistently identified in the circulation of patients with NSAb-mediated diseases, accompanied by high serum levels of autoantigen-specific antibodies. Early evidence suggests that these cells evade well-characterized B cell tolerance checkpoints. Nearer to the site of pathology, cerebrospinal fluid from patients with NSAb-mediated diseases contains high levels of autoantigen-specific B cells that are likely to account for the intrathecal synthesis of these autoantibodies. The characteristics of their immunoglobulin genes offer insights into the underlying immunobiology. In this Review, we summarize the emerging knowledge of B cells across the NSAb-mediated diseases. We review the evidence for the relative contributions of germinal centres and long-lived plasma cells as sources of autoantibodies, discuss data that indicate migration of B cells into the CNS and summarize insights into the underlying B cell pathogenesis that are provided by therapeutic effects.

Gender issues of antibody-mediated diseases in neurology: (NMOSD/autoimmune encephalitis/MG)

Neuromyelitis optica spectrum disorder (NMOSD), autoimmune encephalitis (AE), myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) are antibody-mediated neurological diseases. They have mostly female predominance, affecting many women during childbearing age. Interactions between the underlying disease (or necessary treatment) and pregnancy can occur in every of these illnesses. Herein, we present the characteristics of NMOSD, AE, MG and LEMS in general, and review published data regarding the influence of the different diseases on fertility, pregnancy, puerperium, treatment strategy during pregnancy and post-partum period, and menopause but also male factors. We summarise key elements that should be borne in mind when confronted with such cases.

Emerging drugs for the treatment of neuromyelitis optica

INTRODUCTION

Evidence-based treatment options for neuromyelitis optica spectrum disorders (NMOSD) patients are beginning to enter the market. Where previously, there was only the exclusive use of empiric and off-label immunosuppressants in this rare and devastating central nervous system autoimmune disease.

AREAS COVERED

In accordance to expanding pathogenetic insights, drugs in phase II and III clinical trials are presented in the context of the current treatment situation for acute attacks and immunopreventative strategies in NMOSD. Some such drugs are the 2019-approved complement inhibitor eculizumab, other compounds in late development include its modified successor ravulizumab, IL-6 receptor antibody satralizumab, CD19 targeting antibody inebilizumab and the TACI-Fc fusion protein telitacicept.

EXPERT OPINION

Moving from broad immunosuppression to tailored treatment strategies, the prospects for efficient NMOSD therapy are positive. For the first time in this disease, class I treatment evidence is available, but long-term data will be necessary to confirm the overall promising study results of the compounds close to approval. While drug development still centers around AQP4 antibody seropositive patients, current and future research requires consideration of possible diverging treatment demands for the smaller group of seronegative patients and patients with presence of MOG antibodies.

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.

Comparative Analysis of T-Cell Responses to Aquaporin-4 and Myelin Oligodendrocyte Glycoprotein in Inflammatory Demyelinating Central Nervous System Diseases

Autoantibodies against aquaporin-4 (AQP4-Ab) and myelin oligodendrocyte glycoprotein (MOG-Ab) are associated with rare central nervous system inflammatory demyelinating diseases like neuromyelitis optica spectrum disorders (NMOSD). Previous studies have shown that not only antibodies, but also autoreactive T-cell responses against AQP4 are present in NMOSD. However, no study has yet analyzed the presence of MOG reactive T-cells in patients with MOG antibodies. Therefore, we compared AQP4 and MOG specific peripheral T-cell response in individuals with AQP4-Ab (n = 8), MOG-Ab (n = 10), multiple sclerosis (MS, n = 8), and healthy controls (HC, n = 14). Peripheral blood mononuclear cell cultures were stimulated with eight AQP4 and nine MOG peptides selected from previous studies and a tetanus toxoid peptide mix as a positive control. Antigen-specific T-cell responses were assessed using the carboxyfluorescein diacetate succinimidyl ester proliferation assay and the detection of granulocyte macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-ɤ and interleukin (IL)-4, IL-6, and IL-17A in cell culture supernatants. Additionally, human leukocyte antigen (HLA)-DQ and HLA-DR genotyping of all participants was performed. We classified a T-cell response as positive if proliferation (measured by a cell division index ≥3) was confirmed by the secretion of at least one cytokine. Reactivity against AQP4 peptides was observed in many groups, but the T-cell response against AQP4 p156-170 was present only in patients with AQP4-Ab (4/8, 50%) and absent in patients with MOG-Ab, MS and HC (corrected p = 0.02). This AQP4 p156-170 peptide specific T-cell response was significantly increased in participants with AQP4-Ab compared to those without [Odds ratio (OR) = 59.00, 95% confidence interval-CI 2.70–1,290.86]. Moreover, T-cell responses against at least one AQP4 peptide were also more frequent in participants with AQP4-Ab (OR = 11.45, 95% CI 1.24–106.05). We did not observe any significant differences for the other AQP4 peptides or any MOG peptide. AQP4-Ab were associated with HLA DQB1^*02 (OR = 5.71, 95% CI 1.09–30.07), DRB1^*01 (OR = 9.33, 95% CI 1.50–58.02) and DRB1^*03 (OR = 6.75, 95% CI = 1.19–38.41). Furthermore, HLA DRB1^*01 was also associated with the presence of AQP4 p156-170 reactive T-cells (OR = 31.67, 95% CI 1.30–772.98). To summarize, our findings suggest a role of AQP4-specific, but not MOG-specific T-cells, in NMOSD.

A comparative study on clinical characterizations between acute myelitis onset of neuromyelitis optica spectrum disease and idiopathic transverse myelitis

BACKGROUND/AIMS

Both of neuromyelitis optica spectrum disease (NMOSDs) and idiopathic transverse myelitis (ITM) could present as acute transverse myelitis. However, long-term immunological treatment and prognosis are different for high recurrence of NMOSDs. In this study, we summarized clinical differences between acute attack myelitis of NMOSDs and ITM, we further screened serum auto-antibodies to help understand the two distinct clinical entities.

METHODS

This is a retrospective study on 48 NMOSD patients and 49 ITM patients in neurological department of Nanjing Drum Tower Hospital from 2013 to 2019. Clinical, CSF and MRI profiles on the acute episode were also compared between NMOSD patients and ITM patients. Serum AQP4 and auto-antibodies were tested. Clinical parameters were further compared between NMOSD patients with and without auto-antibodies.

RESULTS

Compared with ITM patients, NMOSD patients manifested with longer vertebral segments (5.42 ± 3.17 segments vs. 2.31 ± 2.36 segments, p < 0.001), higher female/male ratio (13:3 vs. 20:29, p < 0.001), higher IgG index (30.30% vs. 9.09%, p < 0.05). Positive rates of anti-Ro-52 (47.92% vs. 14.29%, p < 0.001), anti-ANAs (50.00% vs.10.20%, p < 0.001) and anti-SSA (35.42% vs. 6.12%, p = 0.001) were significantly higher in the NMOSD patients than the ITM patients. Seropositive Ro-52 and SSA were associated with longer injured spinal cord segments. However, Ro-52 antibody may not be associated with NMOSD relapsing during our follow up.

CONCLUSIONS

NMOSD patients manifested with longer vertebral segments, higher female/male ratio, IgG index, anti-ANAs, anti-Ro-52 and anti-SSA seroprevalence than ITM patients. These features may help clinicians better distinguish NMOSD from ITM and provide long-term immunotherapy reasonably.

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.

The history of neuromyelitis optica. Part 2: 'Spinal amaurosis', or how it all began

Neuromyelitis optica (NMO) was long considered a clinical variant of multiple sclerosis (MS). However, the discovery of a novel and pathogenic anti-astrocytic serum autoantibody targeting aquaporin-4 (termed NMO-IgG or AQP4-Ab), the most abundant water channel protein in the central nervous system, led to the recognition of NMO as a distinct disease entity in its own right and generated strong and persisting interest in the condition. NMO is now studied as a prototypic autoimmune disorder, which differs from MS in terms of immunopathogenesis, clinicoradiological presentation, optimum treatment, and prognosis. While the history of classic MS has been extensively studied, relatively little is known about the history of NMO. In Part 1 of this series we focused on the late 19th century, when the term 'neuromyelitis optica' was first coined, traced the term's origins and followed its meandering evolution throughout the 20th and into the 21st century. Here, in Part 2, we demonstrate that the peculiar concurrence of acute optic nerve and spinal cord affliction characteristic for NMO caught the attention of physicians much earlier than previously thought by re-presenting a number of very early cases of possible NMO that date back to the late 18th and early 19th century. In addition, we comprehensively discuss the pioneering concept of 'spinal amaurosis', which was introduced into the medical literature by ophthalmologists in the first half of the 19th century.

The clinical value of the albumin quotient in patients with neuromyelitis optica spectrum disorder

BACKGROUND

The disruption of the blood-brain barrier (BBB) is common in patients with neuromyelitis optica spectrum disorder (NMOSD), causing pro-inflammatory immune cells to migrate into the central nervous system (CNS) and active demyelinating lesions. Albumin quotient is commonly used as an indicator for BBB permeability or dysfunction, but its potential clinical value in NMOSD treatment has never been explored. The present study investigated the differences in the albumin quotient level among NMOSD patients with different antibodies (AQP4-IgG and MOG-IgG) and the relationship between the albumin quotient and neurological dysfunction.

METHODS

We retrospectively collected data from 141 patients with NMOSD (104 with AQP4-IgG and 37 with MOG-IgG) and reviewed their clinical features and albumin quotient levels.

RESULTS

The percentage of patients with an abnormal albumin quotient was significantly higher in the MOG-IgG group than in the AQP4-IgG group (48.6% vs 27.9%, P = 0.026); albumin quotient levels in the AQP4-IgG-positive group were similar to those in the MOG-IgG groups (5.65 vs 5.8, P = 0.23). Among those with an abnormal quotient, no differences in the proportions of severe neurological disability across treatment were found between patients with AQP4-IgG and those with MOG-IgG (pre-treatment: AQP4-IgG group vs MOG-IgG group: 58.6% vs 38.9%, P = 0.24; post-treatment: AQP4-IgG group vs MOG-IgG group: 31.0% vs 22.2%, P = 0.74).

CONCLUSIONS

The BBB breakdown in NMOSD patients with MOG-IgG may be more common than in those with AQP4-IgG. AQP4-IgG-positive patients and MOG-IgG-positive patients with severe neurological disability tend to exhibit similar disruptions to the BBB.

Clinical Characteristics and Treatment of MOG-IgG-Associated Optic Neuritis

PURPOSE OF REVIEW

Antibodies against myelin oligodendrocyte glycoprotein (MOG) are associated with a unique acquired central nervous system demyelinating disease-termed MOG-IgG-associated disorder (MOGAD)-which has a variety of clinical manifestations, including optic neuritis, transverse myelitis, acute disseminating encephalomyelitis, and brainstem encephalitis. In this review, we summarize the current knowledge of the clinical characteristics, neuroimaging, treatments, and outcomes of MOGAD, with a focus on optic neuritis.

RECENT FINDINGS

The recent development of a reproducible, live cell-based assay for MOG-IgG, has improved our ability to identify and study this disease. Based on contemporary studies, it has become increasingly evident that MOGAD is distinct from multiple sclerosis and aquaporin-4-positive neuromyelitis optica spectrum disorder with different clinical features and treatment outcomes. There is now sufficient evidence to separate MOGAD from other inflammatory central nervous system demyelinating disorders, which will allow focused research on understanding the pathophysiology of the disease. Prospective treatment trials are needed to determine the best course of treatment, and until then, treatment plans must be individualized to the clinical manifestations and severity of disease.