Hematopoietic stem cell transplantation for neuromyelitis optica spectrum disorder. Can immune tolerance be reestablished?

Neuromyelitis optica (NMO), which is also referred to as Devic's disease, was originally considered an aggressive subtype of multiple sclerosis (MS) presenting as optic neuritis and/or extensive transverse myelitis in which 50% of patients become blind or in a wheelchair within 5 years of onset. Subsequently, NMO was categorized as one of a spectrum of inflammatory and demyelinating autoimmune disorders that are distinct from multiple sclerosis and termed neuromyelitis optica spectrum disorder (NMOSD). NMOSD differs from multiple sclerosis by its clinical course, presentation, magnetic resonance imaging findings, clinical presentation, serum biomarker prognosis, and response to treatment. More recently, NMOSD has been subdivided according to auto-antibody status as aquaporin 4 (AQP4) seropositive NMO, myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), and seronegative NMOSD. The only treatment to date that has resulted in treatment-free remissions, now lasting for more than 5-10 years with posttreatment disappearance of anti-AQP4 antibodies, is hematopoietic stem cell transplantation (HSCT) using either an allogeneic (matched sibling or unrelated) donor with a reduced toxicity conditioning regimen or an autologous stem cell source using a nonmyeloablative conditioning regimen of plasmapheresis (PLEX), cyclophosphamide (Cytoxan®), rabbit antithymocyte (ATG), and rituximab (Rituxan®). Post-HSCT long-term resolution of disease activity and disappearance of AQP4 antibodies is consistent with HSCT-induced immune tolerance.

Autologous hematopoietic stem cell transplantation for pediatric autoimmune neurologic disorders.

Autologous hematopoietic stem cell transplantation (aHSCT) may be effective in carefully selected pediatric patients with multiple sclerosis (MS), neuromyelitis optica (NMO), and chronic inflammatory demyelinating polyneuropathy (CIDP). aHSCT for pediatric MS (same as for adults) is performed to eradicate inflammatory autoreactive cells with lympho-ablative regimens and restore immune tolerance. Its therapeutic effect in MS relies on various mechanisms: (1) the immunosuppressive conditioning regimen prior to aHSCT was able to eradicate the autoreactive cells and (2) the regeneration/renewal of the immune system to reset the aberrant immune response against self-antigens. The aHSCT procedure includes the following different steps, as described in this chapter: patient selection through careful pretransplant screening, "wash-out" period from previous treatments, mobilization of hematopoietic stem cells (HSC), conditioning regimen, HSC infusion, and posttransplant monitoring for early and late complications. Moreover, specific aspects of pediatric population undergoing aHSCT are described. According to the available evidence, aHSCT appears to be safe in pediatric MS, obtaining disease control for a prolonged time after the procedure. A reasonable approach in this setting includes the application of less toxic treatments while reserving aHSCT procedure for patients with severe/refractory forms of the disease. The EBMT considers MS, NMO, and CIDP in pediatric patients within the category of the clinical option (CO), where candidates for aHSCT can be selected on the basis of careful consideration of individual case history in the multidisciplinary setting.

NMOSD and MOGAD.

OBJECTIVE: This article reviews the clinical features, MRI characteristics, diagnosis, and treatment of aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). The main differences between these disorders and multiple sclerosis (MS), the most common demyelinating disease of the central nervous system (CNS), are also highlighted. LATEST DEVELOPMENTS: The past 20 years have seen important advances in understanding rare demyelinating CNS disorders associated with AQP4 IgG and myelin oligodendrocyte glycoprotein (MOG) IgG. The rapidly expanding repertoire of immunosuppressive agents approved for the treatment of AQP4-NMOSD and emerging as potentially beneficial in MOGAD mandates prompt recognition of these diseases. Most of the recent literature has focused on the identification of clinical and MRI features that help distinguish these diseases from each other and MS, simultaneously highlighting major diagnostic pitfalls that may lead to misdiagnosis. An awareness of the limitations of currently available assays for AQP4 IgG and MOG IgG detection is fundamental for identifying rare false antibody positivity and avoiding inappropriate treatments. For this purpose, diagnostic criteria have been created to help the clinician interpret antibody testing results and recognize the clinical and MRI phenotypes associated with AQP4-NMOSD and MOGAD. ESSENTIAL POINTS: An awareness of the specific clinical and MRI features associated with AQP4-NMOSD and MOGAD and the limitations of currently available antibody testing assays is crucial for a correct diagnosis and differentiation from MS. The growing availability of effective treatment options will lead to personalized therapies and improved outcomes.

Therapeutic Approach to Autoimmune Neurologic Disorders.

OBJECTIVE: Autoimmune neurologic disorders encompass a broad category of diseases characterized by immune system attack of the central, peripheral, or autonomic nervous systems. This article provides information on both acute and maintenance immunotherapy used to treat autoimmune neurologic disorders as well as a review of symptomatic management and special considerations when caring for patients with these diseases. LATEST DEVELOPMENTS: Over the past 20 years, more than 50 antibodies have been identified and associated with autoimmune neurologic disorders. Although advances in diagnostic testing have allowed for more rapid diagnosis, the therapeutic approach to these disorders has largely continued to rely on expert opinion, case series, and case reports. With US Food and Drug Administration (FDA) approval of biologic agents to treat neuromyelitis optica spectrum disorder (NMOSD) and myasthenia gravis as well as ongoing clinical trials for the treatment of autoimmune encephalitis, the landscape of immunotherapy options continues to expand. Consideration of the unique pathogenesis of individual autoimmune neurologic disorders as well as the mechanism of action of the diverse range of treatment options can help guide treatment decisions today while evidence from clinical trials informs new therapeutics in the future. ESSENTIAL POINTS: Recognizing patients who have a clinical history and examination findings concerning for autoimmune neurologic disorders and conducting a thorough and directed imaging and laboratory evaluation aimed at ruling out mimics, identifying specific autoimmune syndromes, and screening for factors that may have an impact on immunotherapy choices early in the clinical course are essential to providing optimal care for these patients. Providers must consider immunotherapy, symptomatic treatment, and a multidisciplinary approach that addresses each patient's unique needs when treating patients with autoimmune neurologic disorders.

The relationship between neuromyelitis optica spectrum disorder and autoimmune diseases.

Objective: There have been reports of neuromyelitis optica spectrum disorder (NMOSD) coexisting with connective tissue disorders. The objective of this study was to describe the characteristics of NMOSD coexisting with autoimmune diseases (AID). Methods: This retrospective study evaluated NMOSD patients with and without AID. The enrolled patients had at least one attack, with duration of more than 1 year. Data on the demographics, clinical features, and laboratory findings were assessed. The Poisson model was used to investigate the risk factors associated with the annualized relapse rate (ARR), whereas the Cox model was used to evaluate the risk factors for the first relapse. Results: A total of 180 patients (154 women and 26 men) with NMOSD were identified: 45 had AID and 135 did not. Female patients had a higher prevalence of concomitant AID (p = 0.006) and a greater relapse rate within the first year. There were no statistically significant differences in the characteristics of patients. Kaplan-Meier analysis revealed that NMOSD patients with seropositive aquaporin 4 antibodies (AQP4-Ab; log-rank: p = 0.044), had a shorter time to relapse. Patients seropositive for AQP4-Ab (HR = 2.402, 95%CI = 1.092-5.283, p = 0.029) had a higher risk of suffering a first relapse, according to the Cox model. Patients with and without AID showed a similar declining tendency in terms of change in ARR throughout the first 5 years of the disease. The ARR was greater in the first year [incidence rate ratio (IRR) = 1.534, 95%CI = 1.111-2.118] and the first 2 years (IRR = 1.474, 95%CI = 1.056-2.058) in patients with coexisting AID diagnosis prior to the NMOSD onset. Conclusions: Patients with NMOSD with coexisting AID had similar characteristics when compared with those without AID. NMOSD patients with AID diagnosed before onset had a higher risk of relapse in the early stage of the disease.

Paraneoplastic neuromyelitis optica spectrum disorder associated with ovarian dysgerminoma: a case report and literature review.

Neuromyelitis optica spectrum disorder (NMOSD) is a clinical syndrome characterized by attacks of acute optic neuritis and transverse myelitis. We report a case with paraneoplastic NMOSD that improved after immunosuppressive therapy, surgical resection, and chemotherapy. A 48-year-old woman initially presented with gradual binocular visual loss over the course of one week. The patient was evaluated using magnetic resonance imaging (MRI), computed tomography (CT), visual evoked potential (VEP), pathological biopsy, immunohistochemistry, and autoimmune antibody testing. The brain MRI findings were normal. The VEP revealed prolonged P100 latencies in the right eye and an absence of significant waves in the left eye. Positive serum AQP4-IgG antibodies were found. The patient was diagnosed as NMOSD. Then the patient responded well to treatment with methylprednisolone. An ovarian tumor was found in the patient using abdominal MRI and CT. The tumor was surgically resected, and a pathological biopsy revealed that it was ovarian dysgerminoma. The patient received four rounds of chemotherapy after surgery. One month after the final chemotherapy treatment, a positron emission tomography (PET) scan revealed no tumor. The vision of the patient gradually recovered and serum AQP4 was negative. Furthermore, we summarized the characteristics of patients diagnosed with paraneoplastic NMOSD associated with ovarian neoplasms in previous studies. This is a characteristic case of overlapping NMOSD and ovarian dysgerminoma, demonstrating the importance of tumor therapy in cases of paraneoplastic NMOSD.

Protein-A immunoadsorption combined with immunosuppressive treatment in refractory primary Sjögren's syndrome coexisting with NMOSD: a case report and literature review.

The treatment of primary Sjögren's syndrome (pSS) coexisting with neuromyelitis optica spectrum disorder (NMOSD) using protein-A immunoadsorption combined with immunosuppressive therapy has rarely been reported. Herein, we present the case of a 35-year-old female diagnosed with pSS concomitant with NMOSD (pSS-NMOSD) who demonstrated a positive response to protein-A immunoadsorption after failing to respond to therapy comprising high-dose intravenous methylprednisolone (IVMP) and intravenous immunoglobulin (IVIG). Within one week of receiving three sessions of immunoadsorption combined with immunosuppressive treatment, the patient's clinical symptoms (blurred vision, paraparesis, and dysfunctional proprioception) significantly improved. Additionally, a rapid decrease in the circulating levels of Aquaporin-4 immunoglobulin G antibodies (AQP4-IgG), immunoglobulin (Ig) A, IgG, IgM, erythrocyte sedimentation rate (ESR), and rheumatoid factor (RF) were observed. Magnetic resonance imaging (MRI) further revealed a significant reduction in the lesions associated with longitudinal extensive transverse myelitis. During the follow-up period, prednisolone was gradually tapered to a maintenance dose of 5-10 mg/day, whereas mycophenolate mofetil (MMF) was maintained at 1.0-1.5 g/day. The patient's condition has remained stable for four years, with no signs of recurrence or progression observed on imaging examination. Therefore, this case suggests that protein A immunoadsorption may represent a potentially effective therapeutic option for patients with pSS-NMOSD who are refractory to conventional treatments.

Protocol of a prospective multicenter study on comorbidity impact on multiple sclerosis and antibody-mediated diseases of the central nervous system (COMMIT).

Comorbidities in patients with multiple sclerosis (MS) and antibody-mediated diseases of the central nervous system (CNS) including neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein (MOG)-antibody-associated disease (MOGAD) are common and may influence the course of their neurological disease. Comorbidity may contribute to neuronal injury and therefore limit recovery from attacks, accelerate disease progression, and increase disability. This study aims to explore the impact of comorbidity, particularly vascular comorbidity, and related risk factors on clinical and paraclinical parameters of MS, NMOSD and MOGAD. We propose COMMIT, a prospective multicenter study with longitudinal follow-up of patients with MS, NMOSD, and MOGAD, with or without comorbidities, as well as healthy subjects as controls. Subjects will be stratified by age, sex and ethnicity. In consecutive samples we will analyze levels of inflammation and neurodegeneration markers in both fluid and cellular compartments of the peripheral blood and cerebrospinal fluid (CSF) using multiple state-of-the-art technologies, including untargeted proteomics and targeted ultrasensitive ELISA assays and quantitative reverse transcription polymerase chain reaction (RT-qPCR) as well as high-dimensional single-cell technologies i.e., mass cytometry and single-cell RNA sequencing. Algorithm-based data analyses will be used to unravel the relationship between these markers, optical coherence tomography (OCT) and magnetic resonance imaging (MRI), and clinical outcomes including frequency and severity of relapses, long-term disability, and quality of life. The goal is to evaluate the impact of comorbidities on MS, NMOSD, and MOGAD which may lead to development of treatment approaches to improve outcomes of inflammatory demyelinating diseases of the CNS.

The levels of circulating cytokines and risk of neuromyelitis optica spectrum disorder: a Mendelian randomization study.

Background: Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory autoimmune disease affecting the central nervous system (CNS). NMOSD pathogenesis involves systemic inflammation. However, a causal relationship between circulating cytokine levels and NMOSD remains unclear. Methods: Mendelian randomization (MR) approaches were used to investigate the potential association between genetically determined circulating 19 inflammatory cytokines and 12 chemokines levels and the risk of developing NMOSD. Results: After Bonferroni correction, the risk of aquaporin 4-antibody (AQP4-ab)-positive NMOSD was suggested to be causally associated with the circulating levels of three cytokines, including interleukin (IL)-4 [odds ratio (OR): 11.01, 95% confidence interval (CI): 1.16-104.56, P = 0.037], IL-24 (OR: 161.37; 95% CI: 2.46-10569.21, P = 0.017), and C-C motif chemokine 19 (CCL19) (OR: 6.87, 95% CI: 1.78-26.93, P = 0.006). Conclusion: These findings suggest that a genetic predisposition to higher levels of IL-4, IL-24, and CCL19 may exert a causal effect on the risk of AQP4-ab-positive NMOSD. Further studies are warranted to clarify how these cytokines affect the development of AQP4-ab-positive NMOSD.

MOG CNS Autoimmunity and MOGAD.

At one time considered a possible form of neuromyelitis optica (NMO) spectrum disorder (NMOSD), it is now accepted that myelin oligodendrocyte glycoprotein (MOG) antibody (Ab)-associated disorder (MOGAD) is a distinct entity from either NMO or multiple sclerosis (MS) and represents a broad spectrum of clinical phenotypes. Whereas Abs targeting aquaporin-4 (AQP4) in NMO are pathogenic, the extent that anti-MOG Abs contribute to CNS damage in MOGAD is unclear. Both AQP4-specific Abs in NMO and MOG-specific Abs in MOGAD are predominantly IgG1, a T cell-dependent immunoglobulin (Ig) subclass. Key insights in neuroimmunology and MOGAD pathogenesis have been learned from MOG experimental autoimmune encephalomyelitis (EAE), described 2 decades before the term MOGAD was introduced. MOG-specific T cells are required in MOG EAE, and while anti-MOG Abs can exacerbate EAE and CNS demyelination, those Abs are neither necessary nor sufficient to cause EAE. Knowledge regarding the spectrum of MOGAD clinical and radiologic presentations is advancing rapidly, yet our grasp of MOGAD pathogenesis is incomplete. Understanding both the humoral and cellular immunology of MOGAD has implications for diagnosis, treatment, and prognosis.

Acute gastroenteritis and unilateral vision loss leading to a diagnosis of aquaporin-4-IgG seropositive neuromyelitis optica spectrum of disorders in a child: A case of atypical optic neuritis in the era of biomarkers.

Neuromyelitis optica spectrum of disorders is a rare cause of optic neuritis in children. It is a critical diagnosis requiring urgent management, with delays carrying both life- and sight-threatening complications. Most of the published literature on this entity is in adult patients, with only a few case reports to guide management in the paediatric population. The purpose of this article is to shareour experience in the management of this condition in a child, and thus hopefully add to the limited body of knowledge currently available.

Clinical, Demographic, and Radiological Characteristics of Patients Demonstrating Antibodies Against Myelin Oligodendrocyte Glycoprotein

Background: Optic neuritis, myelitis, and neuromyelitis optica spectrum disorder (NMOSD) have been associated with antibodies against myelin oligodendrocyte glycoprotein-immunoglobulin G (anti-MOG-IgG). Furthermore, patients with radiological and demographic features atypical for multiple sclerosis (MS) with optic neuritis and myelitis also demonstrate antibodies against aquaporin-4 and anti-MOG-IgG. However, data on the diagnosis, treatment, follow-up, and prognosis in patients with anti-MOG-IgG are limited. Aims: To evaluate the clinical, radiological, and demographic characteristics of patients with anti-MOG-IgG. Study Design: Multicenter, retrospective, observational study. Methods: Patients with blood samples demonstrating anti-MOG-IgG that had been evaluated at the Neuroimmunology laboratory at Ondokuz Mayis University's Faculty of Medicine were included in the study. Results: Of the 104 patients with anti-MOG-IgG, 56.7% were women and 43.3% were men. Approximately 2.4% of the patients were diagnosed with MS, 15.8% with acute disseminated encephalomyelitis (ADEM), 39.4% with NMOSD, 31.3% with isolated optic neuritis, and 11.1% with isolated myelitis. Approximately 53.1% of patients with spinal involvement at clinical onset demonstrated a clinical course of NMOSD. Thereafter, 8.8% of these patients demonstrated a clinical course similar to MS and ADEM, and 28.1% demonstrated a clinical course of isolated myelitis. The response to acute attack treatment was lower and the disability was higher in patients aged > 40 years than patients aged < 40 years at clinical onset. Oligoclonal band was detected in 15.5% of the patients. Conclusion: For patients with NMOSD and without anti-NMO antibodies, the diagnosis is supported by the presence of anti-MOG-IgG. Furthermore, advanced age at clinical onset, Expanded Disability Status Scale (EDSS) score at clinical onset, spinal cord involvement, and number of attacks may be negative prognostic factors in patients with anti-MOG-IgG.

Case report: Overlap syndrome of neuromyelitis optica spectrum disorder with anti-Argonaute antibodies.

Aquaporin-4 antibodies (AQP4-Abs) are a diagnostic marker for patients with a demyelinating disease called neuromyelitis optica spectrum disorder (NMOSD). Anti-Argonaute antibodies (AGO-Abs) present as potential biomarkers of the overlap syndrome between NMOSD and other autoimmune diseases. In this paper, we present the case of an adult woman with numbness, tingling, and burning sensations in her arms and subsequent bilateral internuclear ophthalmoplegia. Brain-cervical-thoracic magnetic resonance imaging (MRI) showed T2 hyperintensities in the dorsal brainstem and around the midbrain aqueduct and longitudinally transverse myelitis with homogeneous enhancement on gadolinium-enhanced MRI. The contemporaneous detection of AQP4- and AGO-Abs led to a definite diagnosis of overlap syndrome of NMOSD with AGO-Abs. The patient was treated with immunosuppressive agents, including corticosteroids and immunoglobulins, and achieved remission. This case highlights a novel phenotype of NMOSD with AGO-Abs overlap syndrome, which presents with relapsing brainstem syndrome and longitudinally extensive myelitis with acute severe neurological involvement. The promising prognosis of the disease could serve as a distinct clinical profile. Broad screening for antibodies against central nervous system autoimmune antigens is recommended in suspected patients with limited or atypical clinical manifestations.

Interleukin-6 Signaling Blockade Induces Regulatory Plasmablasts in Neuromyelitis Optica Spectrum Disorder.

BACKGROUND AND OBJECTIVES: Interleukin-6 receptor antibodies (IL-6R Abs), including satralizumab, are increasingly used to prevent relapse for neuromyelitis optica spectrum disorder (NMOSD). However, the detailed mechanism of action of this treatment on the lymphocyte phenotype remains unclear. This study focused on B cells in patients with NMOSD, hypothesizing that IL-6R Ab enables B cells to acquire regulatory functions by producing the anti-inflammatory cytokine IL-10. METHODS: Peripheral blood mononuclear cells were stimulated in vitro to induce the expansion of B-cell subsets, double-negative B cells (DNs; CD19+ IgD-, CD27-) and plasmablasts (PBs; CD19+, CD27hi, CD38hi). Whole B cells, DNs, or PBs were isolated after culture with IL-6R Ab, and IL-10 expression was quantified using quantitative PCR and a cytometric bead array. RNA sequencing was performed to identify the marker of regulatory PBs induced by IL-6R Ab. RESULTS: DNs and PBs were observed to expand in patients with NMSOD during the acute attacks. In the in vitro model, IL-6R Ab increased IL-10 expression in B cells. Notably, IL-10 expression increased in PBs but not in DNs. Using RNA sequencing, CD200 was identified as a marker of regulatory PBs among the differentially expressed upregulated genes. CD200+ PBs produced more IL-10 than CD200- PBs. Furthermore, patients with NMOSD who received satralizumab had a higher proportion of CD200+ PBs than patients during the acute attacks. DISCUSSION: Treatment with IL-6 signaling blockade elicited a regulatory phenotype in B cells and PBs. CD200+ PBs may be a marker of treatment responsiveness in the context of NMOSD pathophysiology.

Characterizing mortality in patients with AQP4-Ab+ neuromyelitis optica spectrum disorder.

Neuromyelitis optica spectrum disorder is an autoimmune disease, causing severe disability due to relapses, but recent mortality data are limited. Among 396 patients seropositive for anti-aquaporin-4 antibody from 2014 to 2020 in the United Kingdom, 39 deaths occurred: 19 (48.7%) were unrelated to disease; 14 (35.9%) were severe disability- or relapse-related; and 4 (10.3%) were attributed to malignancy/infection. Mean annual mortality was 1.92% versus 0.63% in the matched population. The standardized mortality ratio was 3.04 (95% confidence interval 1.67-5.30) with 1.29% excess mortality per year in patients. Median Expanded Disability Status Scale before death was 7.0. Results highlight the importance of preventing relapses that drive disability.

Retinal Changes in Double-Antibody Seronegative Neuromyelitis Optica Spectrum Disorders.

BACKGROUND AND OBJECTIVES: To systematically describe the clinical picture of double-antibody seronegative neuromyelitis optica spectrum disorders (DN-NMOSD) with specific emphasis on retinal involvement. METHODS: Cross-sectional data of 25 people with DN-NMOSD (48 eyes) with and without a history of optic neuritis (ON) were included in this study along with data from 25 people with aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorder (AQP4-NMOSD, 46 eyes) and from 25 healthy controls (HCs, 49 eyes) for comparison. All groups were matched for age and sex and included from the collaborative retrospective study of retinal optical coherence tomography (OCT) in neuromyelitis optica (CROCTINO). Participants underwent OCT with central postprocessing and local neurologic examination and antibody testing. Retinal neurodegeneration was quantified as peripapillary retinal nerve fiber layer thickness (pRNFL) and combined ganglion cell and inner plexiform layer thickness (GCIPL). RESULTS: This DN-NMOSD cohort had a history of [median (inter-quartile range)] 6 (5; 9) attacks within their 5 ± 4 years since onset. Myelitis and ON were the most common attack types. In DN-NMOSD eyes after ON, pRNFL (p < 0.001) and GCIPL (p = 0.023) were thinner compared with eyes of HCs. Even after only one ON episode, DN-NMOSD eyes already had considerable neuroaxonal loss compared with HCs. In DN-NMOSD eyes without a history of ON, pRNFL (p = 0.027) and GCIPL (p = 0.022) were also reduced compared with eyes of HCs. However, there was no difference in pRNFL and GCIPL between DN-NMOSD and AQP4-NMOSD for the whole group and for subsets with a history of ON and without a history of ON-as well as between variances of retinal layer thicknesses. DISCUSSION: DN-NMOSD is characterized by severe retinal damage after ON and attack-independent retinal neurodegeneration. Most of the damage occurs during the first ON episode, which highlights the need for better diagnostic markers in DN-NMOSD to facilitate an earlier diagnosis as well as for effective and early treatments. In this study, people with DN-NMOSD presented with homogeneous clinical and imaging findings potentially suggesting a common retinal pathology in these patients.

Human NMO-IgG Induced Different Pathological and Immunological Changes in the CNS and Peripheral Tissues of Mice.

OBJECTIVES: The majority of neuromyelitis optica spectrum disorders (NMOSD) patients are seropositive for aquaporin-4 (AQP4)-specific antibodies [also named neuromyelitis optica immunoglobulin G antibodies (NMO-IgG)]. Although NMO-IgG can induce pathological changes in the central nervous system (CNS), the immunological changes in the CNS and peripheral tissue remain largely unknown. We investigated whether NMO-IgG binds to tissue expressing AQP4 and induces immunological changes in the peripheral tissue and CNS. METHODS: C57BL/6 female mice were assigned into an NMOSD or control group. Pathological and immunological changes in peripheral tissue and CNS were measured by immunostaining and flow cytometry, respectively. Motor impairment was measured by open-field test. RESULTS: We found that NMO-IgG did bind to astrocyte- and AQP4-expressing peripheral tissue, but induced glial fibrillary acidic protein and AQP4 loss only in the CNS. NMO-IgG induced the activation of microglia and modulated microglia polarization toward the classical (M1) phenotype, but did not affect innate or adaptive immune cells in the peripheral immune system, such as macrophages, neutrophils, Th17/Th1, or IL-10-producing B cells. In addition, NMOSD mice showed significantly less total distance traveled and higher immobility time in the open field. CONCLUSIONS: We found that injection of human NMO-IgG led to astrocytopathic lesions with microglial activation in the CNS. However, there were no significant pathological or immunological changes in the peripheral tissues.

Serum Proteomics Distinguish Subtypes of NMO Spectrum Disorder and MOG Antibody-Associated Disease and Highlight Effects of B-Cell Depletion.

BACKGROUND AND OBJECTIVES: AQP4 antibody-positive NMOSD (AQP4-NMOSD), MOG antibody-associated disease (MOGAD), and seronegative NMOSD (SN-NMOSD) are neuroautoimmune conditions that have overlapping clinical manifestations. Yet, important differences exist in these diseases, particularly in B-cell depletion (BCD) efficacy. Yet, the biology driving these differences remains unclear. Our study aims to clarify biological pathways distinguishing these diseases beyond autoantibodies and investigate variable BCD effects through proteomic comparisons. METHODS: In a retrospective study, 1,463 serum proteins were measured in 53 AQP4-NMOSD, 25 MOGAD, 18 SN-NMOSD, and 49 healthy individuals. To identify disease subtype-associated signatures, we examined serum proteins in patients without anti-CD20 B-cell depletion (NoBCD). We then assessed the effect of BCD treatment within each subtype by comparing proteins between BCD-treated and NoBCD-treated patients. RESULTS: In NoBCD-treated patients, serum profiles distinguished the 3 diseases. AQP4-NMOSD showed elevated type I interferon-induced chemokines (CXCL9 and CXCL10) and TFH chemokine (CXCL13). MOGAD exhibited increased cytotoxic T-cell proteases (granzyme B and granzyme H), while SN-NMOSD displayed elevated Wnt inhibitory factor 1, a marker for nerve injury. Across all subtypes, BCD-treated patients showed reduction of B-cell-associated proteins. In AQP4-NMOSD, BCD led to a decrease in several inflammatory pathways, including IL-17 signaling, cytokine storm, and macrophage activation. By contrast, BCD elevated these pathways in patients with MOGAD. BCD had no effect on these pathways in SN-NMOSD. DISCUSSION: Proteomic profiles show unique biological pathways that distinguish AQP4-NMOSD, MOGAD, or SN-NMOSD. Furthermore, BCD uniquely affects inflammatory pathways in each disease type, providing an explanation for the disparate therapeutic response in AQP4-NMOSD and MOGAD.

A comparative study of hypothalamic involvement in patients with myelin oligodendrocyte glycoprotein antibody-associated disease, neuromyelitis optica spectrum disorder, and multiple sclerosis.

BACKGROUND AND PURPOSE: We aimed to characterize hypothalamic involvement in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and compare it with neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS). METHODS: A retrospective study was performed to identify hypothalamic lesions in patients diagnosed with MOGAD, NMOSD, or MS from January 2013 to May 2020. The demographic, clinical, and radiological features were recorded. Hypothalamic dysfunction and prognosis were assessed through physical examination, biochemical testing, sleep monitoring, and magnetic resonance imaging. RESULTS: Hypothalamic lesions were observed in seven of 96 patients (7.3%) with MOGAD, 34 of 536 (6.3%) with NMOSD, and 16 of 356 (4.5%) with MS (p = 0.407). The time from disease onset to development of hypothalamic lesions was shortest in MOGAD (12 months). The frequency of bilateral hypothalamic lesions was the lowest in MOGAD (p = 0.008). The rate of hypothalamic dysfunction in MOGAD was 28.6%, which was lower than that in NMOSD (70.6%) but greater than that in MS patients (18.8%; p = 0.095 and p = 0.349, respectively). Hypothalamic dysfunction in MOGAD manifests as hypothalamic-pituitary-adrenal axis dysfunction and hypersomnia. The proportion of complete regression of hypothalamic lesions in MOGAD (100%) was much greater than that in NMOSD (41.7%) and MS patients (18.2%; p = 0.007 and p = 0.001, respectively). An improvement in hypothalamic dysfunction was observed in all MOGAD patients after immunotherapy. CONCLUSIONS: MOGAD patients have a relatively high incidence of asymptomatic hypothalamic lesions. The overall prognosis of patients with hypothalamic involvement is good in MOGAD, as the lesions completely resolve, and dysfunction improves after immunotherapy.

MOG Antibody Disease: Nuances in Presentation, Diagnosis, and Management.

PURPOSE OF REVIEW: Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) is a distinct neuroinflammatory condition characterized by attacks of optic neuritis, transverse myelitis, and other demyelinating events. Though it can mimic multiple sclerosis and neuromyelitis optica spectrum disorder, distinct clinical and radiologic features which can discriminate these conditions are now recognized. This review highlights recent advances in our understanding of clinical manifestations, diagnosis, and treatment of MOGAD. RECENT FINDINGS: Studies have identified subtleties of common clinical attacks and identified more rare phenotypes, including cerebral cortical encephalitis, which have broadened our understanding of the clinicoradiologic spectrum of MOGAD and culminated in the recent publication of proposed diagnostic criteria with a familiar construction to those diagnosing other neuroinflammatory conditions. These criteria, in combination with advances in antibody testing, should simultaneously lead to wider recognition and reduced incidence of misdiagnosis. In addition, recent observational studies have raised new questions about when to treat MOGAD chronically, and with which agent. MOGAD pathophysiology informs some of the relatively unique clinical and radiologic features which have come to define this condition, and similarly has implications for diagnosis and management. Further prospective studies and the first clinical trials of therapeutic options will answer several remaining questions about the peculiarities of this condition.