Antibody to aquaporin-4 in the long-term course of neuromyelitis optica

Role of soluble biomarkers in treating multiple sclerosis and neuroinflammatory conditions

Multiple sclerosis (MS) is a complex, chronic immune-mediated disease characterized by acute and progressive inflammatory damage of the central nervous system. MS manifests clinically with unpredictable neurological symptoms from focal inflammatory attacks as well as gradual neurodegeneration which contribute significantly to long-term disability progression. As treatment options advance, developing more personalized strategies capture heterogeneous mechanisms of injury which may be targeted or predict outcomes has been a focus of ongoing investigation. The role of soluble biomarkers has emerged as a pivotal tool to assist in these goals. Early promising candidates include neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP); these intermediate filaments that are expressed in neurons and astrocytes, respectively, are reliably measurable from blood samples and can reveal clinical and subclinical changes, as well as predict progression. Changes in these biomarkers can indicate a response to therapy, thus potentially be used as endpoints in clinical trials. Furthermore, recent research has identified a potential role of these and other soluble biomarkers in other neuroimmunological conditions including neuromyelitis spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein associated disease (MOGAD), autoimmune encephalitis, neurosarcoidosis, neuropsychiatric involvement in connective tissue disorders and vasculitides, and a host of neurodegenerative conditions. By integrating biomarker analysis into routine clinical assessments, healthcare providers may move toward a more nuanced and individualized care model, better equipped to meet the challenges posed by these multifaceted diseases. Understanding the dynamics of these biomarkers has many applications that can improve personalized medicine in MS.

Integrated omics profiling reveals systemic dysregulation and potential biomarkers in the blood of patients with neuromyelitis optica spectrum disorders

BACKGROUND

Neuromyelitis optica spectrum disorders (NMOSD) are autoimmune conditions that affect the central nervous system. The contribution of peripheral abnormalities to the disease's pathogenesis is not well understood.

METHODS

To investigate this, we employed a multi-omics approach analyzing blood samples from 52 NMOSD patients and 46 healthy controls (HC). This included mass cytometry, cytokine arrays, and targeted metabolomics. We then analyzed the peripheral changes of NMOSD, and features related to NMOSD's disease severity. Furthermore, an integrative analysis was conducted to identify the distinguishing characteristics of NMOSD from HC. Additionally, we unveiled the variations in peripheral features among different clinical subgroups within NMOSD. An independent cohort of 40 individuals with NMOSD was utilized to assess the serum levels of fibroblast activation protein alpha (FAP).

RESULTS

Our analysis revealed a distinct peripheral immune and metabolic signature in NMOSD patients. This signature is characterized by an increase in monocytes and a decrease in regulatory T cells, dendritic cells, natural killer cells, and various T cell subsets. Additionally, we found elevated levels of inflammatory cytokines and reduced levels of tissue-repair cytokines. Metabolic changes were also evident, with higher levels of bile acids, lactates, triglycerides, and lower levels of dehydroepiandrosterone sulfate, homoarginine, octadecadienoic acid (FA[18:2]), and sphingolipids. We identified distinctive biomarkers differentiating NMOSD from HC and found blood factors correlating with disease severity. Among these, fibroblast activation protein alpha (FAP) was a notable marker of disease progression.

CONCLUSIONS

Our comprehensive blood profile analysis offers new insights into NMOSD pathophysiology, revealing significant peripheral immune and metabolic alterations. This work lays the groundwork for future biomarker identification and mechanistic studies in NMOSD, highlighting the potential of FAP as a marker of disease progression.

Update on aquaporin-4 antibody detection: the early diagnosis of neuromyelitis optica spectrum disorders

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune-mediated primary inflammatory myelinopathy of the central nervous system that primarily affects the optic nerve and spinal cord. The aquaporin 4 antibody (AQP4-Ab) is a specific autoantibody marker for NMOSD. Most patients with NMOSD are seropositive for AQP4-Ab, thus aiding physicians in identifying ways to treat NMOSD. AQP4-Ab has been tested in many clinical and laboratory studies, demonstrating effectiveness in diagnosing NMOSD. Recently, novel assays have been developed for the rapid and accurate detection of AQP4-Ab, providing further guidance for the diagnosis and treatment of NMOSD. This article summarizes the importance of rapid and accurate diagnosis for treating NMOSD based on a review of the latest relevant literature. We discussed current challenges and methods for improvement to offer new ideas for exploring rapid and accurate AQP4-Ab detection methods, aiming for early diagnosis of NMOSD.

B cell and aquaporin-4 antibody relationships with neuromyelitis optica spectrum disorder activity

This post hoc analysis of the randomized, placebo-controlled N-MOmentum study (NCT02200770) of inebilizumab in neuromyelitis optica spectrum disorder (NMOSD) evaluated relationships between circulating B-cell subsets and aquaporin-4 immunoglobulin G (AQP4-lgG) titers and attacks. Among participants receiving placebo, CD20+ and CD27+ B-cell counts were modestly increased from the pre-attack visit to attack; plasmablast/plasma cell gene signature was increased from baseline to the pre-attack visit (p = 0.016) and from baseline to attack (p = 0.009). With inebilizumab treatment, B-cell subset counts decreased and did not increase with attacks. No difference in change of AQP4-IgG titers from baseline to time of attack was observed.

Neuromyelitis optica spectrum disorder: pathophysiological approach

Aim: To review the main pathological findings of Neuromyelitis Optica Spectrum Disorder (NMOSD) associated with the presence of autoantibodies to aquaporin-4 (AQP4) as well as the mechanisms of astrocyte dysfunction and demyelination. Methods: An comprehensive search of the literature in the field was carried out using the database of The National Center for Biotechnology Information from . Systematic searches were performed until July 2022. Results: NMOSD is an inflammatory and demyelinating disease of the central nervous system mainly in the areas of the optic nerves and spinal cord, thus explaining mostly the clinical findings. Other areas affected in NMOSD are the brainstem, hypothalamus, and periventricular regions. Relapses in NMOSD are generally severe and patients only partially recover. NMOSD includes clinical conditions where autoantibodies to aquaporin-4 (AQP4-IgG) of astrocytes are detected as well as similar clinical conditions where such antibodies are not detected. AQP4 are channel-forming integral membrane proteins of which AQ4 isoforms are able to aggregate in supramolecular assemblies termed orthogonal arrays of particles (OAP) and are essential in the regulation of water homeostasis and the adequate modulation of neuronal activity and circuitry. AQP4 assembly in orthogonal arrays of particles is essential for AQP4-IgG pathogenicity since AQP4 autoantibodies bind to OAPs with higher affinity than for AQP4 tetramers. NMOSD has a complex background with prominent roles for genes encoding cytokines and cytokine receptors. AQP4 autoantibodies activate the complement-mediated inflammatory demyelination and the ensuing damage to AQP4 water channels, leading to water influx, necrosis and axonal loss. Conclusions: NMOSD as an astrocytopathy is a nosological entity different from multiple sclerosis with its own serological marker: immunoglobulin G-type autoantibodies against the AQP4 protein which elicits a complement-dependent cytotoxicity and neuroinflammation. Some patients with typical manifestations of NMSOD are AQP4 seronegative and myelin oligodendrocyte glycoprotein positive. Thus, the detection of autoantibodies against AQP4 or other autoantibodies is crucial for the correct treatment of the disease and immunosuppressant therapy is the first choice.

Correlation between severe attacks and serum aquaporin-4 antibody titer in neuromyelitis optica spectrum disorder

Aquaporin 4-immunoglobulin G (AQP4-IgG) specifically targets aquaporin 4 in approximately 80% of Neuromyelitis Optica Spectrum Disorder (NMOSD) cases. NMOSD is presently categorized as anti-AQP4-antibody (Ab) positive or negative based on AQP4-Ab presence. The association between antibody titers and patient prognosis remains unclear. Therefore, the present study explores the correlation between severe attacks and serum AQP4 Ab titers in patients with neuromyelitis optica spectrum disorder. Data were gathered retrospectively from 546 patients with NMOSD between September 1, 2009, and December 1, 2021. Patients were categorized based on their AQP4-Ab titers: AQP4 titer ≥ 1:320 were classified as the high-titer group, AQP4 (+ +), and AQP4 titer of ≤ 1:100 were classified as the low-titer group, AQP4 ( +). Clinical characteristics and prognoses between the two groups were compared. Patients with AQP4 ( +) exhibited few severe optic neuritis (SON) attacks (false discovery rate [FDR] corrected p < 0.001), a reduced percentage experiencing SON attacks, and a lower incidence of visual disability than patients with AQP4 (+ +). Patients with AQP4 (+ +) and AQP4 ( +) NMOSD exhibited significant difference in annual recurrence rate (ARR) (FDR-corrected p < 0.001). The lower AQP4 Ab titer group demonstrated reduced susceptibility to severe relapse with conventional immunosuppressive agents and rituximab (RTX) than the higher titer group. No significant differences in sex, age at onset, coexisting connective tissue diseases, motor disability, or mortality rates were observed between the two groups. Higher AQP4 Ab titers correlated with increased disease severity and visual disability in patients with NMOSD.

Moving towards a new era for the treatment of neuromyelitis optica spectrum disorders

Neuromyelitis optica spectrum disorders (NMOSD) include a rare group of autoimmune conditions that primarily affect the central nervous system. They are characterized by inflammation and damage to the optic nerves, brain and spinal cord, leading to severe vision impairment, locomotor disability and sphynteric disturbances. In the majority of cases, NMOSD arises due to specific serum immunoglobulin G (IgG) autoantibodies targeting aquaporin 4 (AQP4-IgG), which is the most prevalent water-channel protein of the central nervous system. Early diagnosis and treatment are crucial to manage symptoms and prevent long-term disability in NMOSD patients. NMOSD were previously associated with a poor prognosis. However, recently, a number of randomized controlled trials have demonstrated that biological therapies acting on key elements of NMOSD pathogenesis, such as B cells, interleukin-6 (IL-6) pathway, and complement, have impressive efficacy in preventing the occurrence of clinical relapses. The approval of the initial drugs marks a revolutionary advancement in the treatment of NMOSD patients, significantly transforming therapeutic options and positively impacting their prognosis. In this review, we will provide an updated overview of the key immunopathological, clinical, laboratory, and neuroimaging aspects of NMOSD. Additionally, we will critically examine the latest advancements in NMOSD treatment approaches. Lastly, we will discuss key aspects regarding optimization of treatment strategies and their monitoring.

Unveiling the proteome-wide autoreactome enables enhanced evaluation of emerging CAR T cell therapies in autoimmunity

Given the global surge in autoimmune diseases, it is critical to evaluate emerging therapeutic interventions. Despite numerous new targeted immunomodulatory therapies, comprehensive approaches to apply and evaluate the effects of these treatments longitudinally are lacking. Here, we leveraged advances in programmable-phage immunoprecipitation methodology to explore the modulation, or lack thereof, of autoantibody profiles, proteome-wide, in both health and disease. Using a custom set of over 730,000 human-derived peptides, we demonstrated that each individual, regardless of disease state, possesses a distinct and complex constellation of autoreactive antibodies. For each individual, the set of resulting autoreactivites constituted a unique immunological fingerprint, or "autoreactome," that was remarkably stable over years. Using the autoreactome as a primary output, we evaluated the relative effectiveness of various immunomodulatory therapies in altering autoantibody repertoires. We found that therapies targeting B cell maturation antigen (BCMA) profoundly altered an individual's autoreactome, while anti-CD19 and anti-CD20 therapies had minimal effects. These data both confirm that the autoreactome comprises autoantibodies secreted by plasma cells and strongly suggest that BCMA or other plasma cell-targeting therapies may be highly effective in treating currently refractory autoantibody-mediated diseases.

Soluble biomarkers for Neuromyelitis Optica Spectrum Disorders: a mini review

The Neuromyelitis Optica Spectrum Disorders (NMOSD) constitute a spectrum of rare autoimmune diseases of the central nervous system characterized by episodes of transverse myelitis, optic neuritis, and other demyelinating attacks. Previously thought to be a subtype of multiple sclerosis, NMOSD is now known to be a distinct disease with unique pathophysiology, clinical course, and treatment options. Although there have been significant recent advances in the diagnosis and treatment of NMOSD, the field still lacks clinically validated biomarkers that can be used to stratify disease severity, monitor disease activity, and inform treatment decisions. Here we review many emerging NMOSD biomarkers including markers of cellular damage, neutrophil-to-lymphocyte ratio, complement, and cytokines, with a focus on how each biomarker can potentially be used for initial diagnosis, relapse surveillance, disability prediction, and treatment monitoring.

Chimeric AQP4-based immunosorbent for highly-specific removal of AQP4-IgG from blood

Anti-aquaporin-4 autoantibodies (AQP4-IgG) are implicated in the pathogenesis of neuromyelitis optica spectrum disorders (NMOSD), and their removal from the blood circulation is considered to be an effective method for acute treatment. An ideal extracorporeal AQP4-IgG removal system should have high specificity, which means that it can selectively remove AQP4-IgG without affecting normal immunoglobulins. However, the conventional tryptophan immobilized column lacks sufficient specificity and cannot achieve this goal. In this study, we successfully prepared a fusion protein chimeric AQP4, which consists of the complete antigenic epitopes of human AQP4 and the constant region of scaffold protein DARPin. Chimeric AQP4 was expressed and purified from Escherichia coli, and then immobilized on agarose gel as a ligand for selective capture of AQP4-IgG immunosorbent. The prepared immunosorbent had a theoretical maximum adsorption capacity of 20.48 mg/g gel estimated by Langmuir isotherm. In vitro plasma perfusion tests demonstrated that the chimeric AQP4 coupled adsorbent had remarkable adsorption performance, and could eliminate more than 85 % of AQP4-IgG under the gel-to-plasma ratio of 1:50. Moreover, it exhibited high specificity because other human plasma proteins were not adsorbed in the dynamic adsorption experiment. These results suggest that the chimeric AQP4 coupled immunosorbent can provide a new approach for specific immunoadsorption (IA) treatment of NMOSD.

Treatment of neuromyelitis optica spectrum disorder: revisiting the complement system and other aspects of pathogenesis

Neuromyelitis optica spectrum disorder (NMOSD) represents a rare neuroimmunological disease causing recurrent attacks and accumulation of permanent disability in affected patients. The discovery of the pathogenic IgG‑1 antibody targeting a water channel expressed in astrocytes, aquaporin 4, constitutes a milestone achievement. Subsequently, multiple pathophysiological aspects of this distinct disease entity have been investigated. Demyelinating lesions and axonal damage ensue from autoantibodies targeting an astroglial epitope. This conundrum has been addressed in the current disease model, where activation of the complement system as well as B cells and interleukin 6 (IL-6) emerged as key contributors. It is the aim of this review to address these factors in light of novel treatment compounds which reflect these pathophysiological concepts in aiming for attack prevention, thus reducing disease burden in patients with NMOSD.

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.

A Case Report of NMO Transverse Myelitis

BACKGROUND

Transverse myelitis is considered one of the cardinal features of neuromyelitis optica spectrum disorder (NMOSD), an immune-mediated inflammatory condition of the CNS characterized by severe, immune-mediated demyelination and axonal damage predominantly targeting optic nerves and spinal cord. We describe a case in which a diagnosis of NMOSD was established, associated with West Nile Virus (WNV) infection.

CASE PRESENTATION

A healthy 18-year-old female presented with intractable hiccups and rapidly progressing paraparesis. MRI demonstrated T2 edema extending from the medulla to the conus, consistent with longitudinally extensive transverse myelitis. Serum and CSF Aquaporin-4 IgG (AQP4) were both positive with high titers. In conjunction with antiviral therapy, immunomodulatory treatment was initiated using pulse methylprednisolone, plasmapheresis and Rituximab. A month and a half after admission, the patient was fully ambulatory with no residual symptoms. On her rheumatology follow-up visit, West Nile Virus-specific IgM in CSF was found to be positive from the patient's initial presentation.

CONCLUSION

We propose that West Nile Virus may have been the autoimmune trigger to the patient's development of NMOSD, highlighting the importance of evaluating viral triggers in autoimmune diseases.

Expression analysis of Treg-related lncRNAs in neuromyelitis optica spectrum disorder

Neuromyelitis Optica Spectrum Disorder (NMOSD) is an autoimmune condition affecting the central nervous system, in which various kinds of immune cells, including T and B cells, and numerous cytokines and chemokines are implicated. LncRNAs modulating the function or differentiation of regulatory T cells (Tregs) may be involved in the pathoetiology of NMO. To assess the involvement of these lncRNAs in this disease, we studied the expression levels of TH2-LCR, MAFTRR, NEST, RMRP, and FLICR in NMO patients and healthy subjects. All of the lncRNAs listed were up-regulated in NMO patients compared with healthy controls. Although the interaction of group and gender factors significantly affected the expression of NEST, RMRP, and TH2-LCR genes, we detected no effect of gender factor on the expression of the examined genes. The highest expression correlation was found between RMRP and TH2-LCR among cases with correlation coefficient 0.73. ROC curve analysis indicated that TH2-LCR, MAFTRR, RMRP, and FLICR had significant prospective diagnostic power (AUC ± SD = 0.99 ± 0.002, 0.97 ± 0.01, 0.91 ± 0.01 and 0.84 ± 0.04, respectively). Best of these genes was TH2-LCR with AUC ± SD = 0.99 ± 0.002, sensitivity= 0.97, specificity= 1, P-value= <0.0001. RMRP and TH2-LCR had a positive correlation with age and age at onset and a negative correlation with EDSS. Cumulatively, TH2-LCR, MAFTRR, RMRP, and FLICR lncRNAs, particularly TH2-LCR, could be considered as potential contributors to the pathogenesis of NMO disease.

Update on the diagnosis and treatment of neuromyelitis optica spectrum disorders (NMOSD) - revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part II: Attack therapy and long-term management

This manuscript presents practical recommendations for managing acute attacks and implementing preventive immunotherapies for neuromyelitis optica spectrum disorders (NMOSD), a rare autoimmune disease that causes severe inflammation in the central nervous system (CNS), primarily affecting the optic nerves, spinal cord, and brainstem. The pillars of NMOSD therapy are attack treatment and attack prevention to minimize the accrual of neurological disability. Aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) are a diagnostic marker of the disease and play a significant role in its pathogenicity. Recent advances in understanding NMOSD have led to the development of new therapies and the completion of randomized controlled trials. Four preventive immunotherapies have now been approved for AQP4-IgG-positive NMOSD in many regions of the world: eculizumab, ravulizumab - most recently-, inebilizumab, and satralizumab. These new drugs may potentially substitute rituximab and classical immunosuppressive therapies, which were as yet the mainstay of treatment for both, AQP4-IgG-positive and -negative NMOSD. Here, the Neuromyelitis Optica Study Group (NEMOS) provides an overview of the current state of knowledge on NMOSD treatments and offers statements and practical recommendations on the therapy management and use of all available immunotherapies for this disease. Unmet needs and AQP4-IgG-negative NMOSD are also discussed. The recommendations were developed using a Delphi-based consensus method among the core author group and at expert discussions at NEMOS meetings.

Bruton's tyrosine kinase-bearing B cells and microglia in neuromyelitis optica spectrum disorder

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory autoimmune disease of the central nervous system that involves B-cell receptor signaling as well as astrocyte-microglia interaction, which both contribute to evolution of NMOSD lesions.

MAIN BODY

Through transcriptomic and flow cytometry analyses, we found that Bruton's tyrosine kinase (BTK), a crucial protein of B-cell receptor was upregulated both in the blood and cerebrospinal fluid of NMOSD patients. Blockade of BTK with zanubrutinib, a highly specific BTK inhibitor, mitigated the activation and maturation of B cells and reduced production of causal aquaporin-4 (AQP4) autoantibodies. In a mouse model of NMO, we found that both BTK and pBTK expression were significantly increased in microglia. Transmission electron microscope scan demonstrated that BTK inhibitor ameliorated demyelination, edema, and axonal injury in NMO mice. In the same mice colocalization of GFAP and Iba-1 immunofluorescence indicated a noticeable increase of astrocytes-microglia interaction, which was alleviated by zanubrutinib. The smart-seq analysis demonstrated that treatment with BTK inhibitor instigated microglial transcriptome changes including downregulation of chemokine-related genes and genes involved in the top 5 biological processes related to cell adhesion and migration, which are likely responsible for the reduced crosstalk of microglia and astrocytes.

CONCLUSIONS

Our results show that BTK activity is enhanced both in B cells and microglia and BTK inhibition contributes to the amelioration of NMOSD pathology. These data collectively reveal the mechanism of action of BTK inhibition and corroborate BTK as a viable therapeutic target.

Unveiling the autoreactome: Proteome-wide immunological fingerprints reveal the promise of plasma cell depleting therapy

The prevalence and burden of autoimmune and autoantibody mediated disease is increasing worldwide, yet most disease etiologies remain unclear. Despite numerous new targeted immunomodulatory therapies, comprehensive approaches to apply and evaluate the effects of these treatments longitudinally are lacking. Here, we leverage advances in programmable-phage immunoprecipitation (PhIP-Seq) methodology to explore the modulation, or lack thereof, of proteome-wide autoantibody profiles in both health and disease. We demonstrate that each individual, regardless of disease state, possesses a distinct set of autoreactivities constituting a unique immunological fingerprint, or "autoreactome", that is remarkably stable over years. In addition to uncovering important new biology, the autoreactome can be used to better evaluate the relative effectiveness of various therapies in altering autoantibody repertoires. We find that therapies targeting B-Cell Maturation Antigen (BCMA) profoundly alter an individual's autoreactome, while anti-CD19 and CD-20 therapies have minimal effects, strongly suggesting a rationale for BCMA or other plasma cell targeted therapies in autoantibody mediated diseases.

Glutamate as a new path in discrimination between neuromyelitis optica spectrum disorder and multiple sclerosis

Background

Neuromyelitis optica spectrum disorder (NMOSD) used to be considered as a variant of multiple sclerosis (MS), however the recent detection of a highly specific serum biomarkers for NMOSD have made clear that NMOSD is a condition distinct from MS. The aim was to explore the role of serum glutamate level in the discrimination between NMOSD and relapsing remitting (RR) MS patients during and in between relapses. The study comprised two groups; first group, a total of 30 NMOSD patients, they were furtherly subdivided into NMOSD in remission, 15 patients without recent relapses in the last 3 months, NMOSD with relapse, 15 patients with recent relapses in the last 3 months, the second group, 30 definite, RRMS patients, they were further subdivided into RRMS in remission, 15 patients without recent relapses in the last 3 months RRMS with relapse, 15 patients with recent relapses in the last 3 months.

Results

Without relapse, NMOSD patients have higher level of serum glutamate than RRMS patients with (P values = 0.005), a significant difference between EDSS in NMOSD patients and RRMS patients (P = 0.0001), The cut-off value of glutamate serum level between NMOSD in remission and RRMS in remission was > 10.3 μg/mL, yet its level for differentiation between group RRMS in remission and RRMS with relapse was > 12.6 μg/mL.

Conclusion

Glutamate cut-off value might be a reliable tool to discriminate between NMOSD and RRMS.

Investigation of sexual dysfunction and depression prevalence in neuromyelitis optica spectrum disorder

OBJECTIVE

To investigate the prevalence of sexual dysfunction (SD) and depression in patients with neuromyelitis optica (NMO), a demyelinating disorder of the central nervous system.

METHODS

A total of 110 NMO patients and 112 healthy individuals were included as a control group, and their SD was assessed using the Female Sexual Function Inventory (FSFI) and the International Index of Erectile Function (IIEF) for women and men, respectively. The FSFI categorizes female sexual dysfunction into six subscores, including libido, arousal, lubrication, orgasm, sexual satisfaction, and pain, while the IIEF categorizes male sexual dysfunction into five subscores, including sexual desire, erection, orgasm, intercourse satisfaction, and overall satisfaction.

RESULTS

SD was prevalent among NMO patients, with 78% of female patients and 63.2% of male patients reporting SD in at least one subscore. The severity of the disease, as measured by the Expanded Disability Status Scale (EDSS), was found to be significantly correlated with SD in all subscores, while the duration of the disease was only correlated with the overall satisfaction subscore in men and the pain subscore in women. Furthermore, SD was found to be significantly correlated with depression in these patients.

CONCLUSION

The study highlights the importance of addressing SD and depression in NMO patients, as they adversely affect the quality of life. The findings suggest that the physical aspects of SD are mostly affected by the severity of the disease, while psychological aspects are highly correlated with the chronicity of the disease.

Alterations in Aquaporin-4-IgG Serostatus in 986 Patients: A Laboratory-Based Longitudinal Analysis

OBJECTIVE

This study was undertaken to investigate factors associated with aquaporin-4 (AQP4)-IgG serostatus change using a large serological database.

METHODS

This retrospective study utilizes Mayo Clinic Neuroimmunology Laboratory data from 2007 to 2021. We included all patients with ≥2 AQP4-IgG tests (by cell-based assay). The frequency and clinical factors associated with serostatus change were evaluated. Multivariable logistic regression analysis examined whether age, sex, or initial titer was associated with serostatus change.

RESULTS

There were 933 patients who had ≥2 AQP4-IgG tests with an initial positive result. Of those, 830 (89%) remained seropositive and 103 (11%) seroreverted to negative. Median interval to seroreversion was 1.2 years (interquartile range [IQR] = 0.4-3.5). Of those with sustained seropositivity, titers were stable in 92%. Seroreversion was associated with age ≤ 20 years (odds ratio [OR] = 2.25; 95% confidence interval [CI] = 1.09-4.63; p = 0.028) and low initial titer of ≤1:100 (OR = 11.44, 95% CI = 3.17-41.26, p < 0.001), and 5 had clinical attacks despite seroreversion. Among 62 retested after seroreversion, 50% returned to seropositive (median = 224 days, IQR = 160-371). An initial negative AQP4-IgG test occurred in 9,308 patients. Of those, 99% remained seronegative and 53 (0.3%) seroconverted at a median interval of 0.76 years (IQR = 0.37-1.68).

INTERPRETATION

AQP4-IgG seropositivity usually persists over time with little change in titer. Seroreversion to negative is uncommon (11%) and associated with lower titers and younger age. Seroreversion was often transient, and attacks occasionally occurred despite prior seroreversion, suggesting it may not reliably reflect disease activity. Seroconversion to positive is rare (<1%), limiting the utility of repeat testing in seronegative patients unless clinical suspicion is high. ANN NEUROL 2023;94:727-735.

Neuromyelitis Optica Spectrum Disorders: Clinical Perspectives, Molecular Mechanisms, and Treatments

Neuromyelitis optica (NMO) is a rare autoimmune inflammatory disorder affecting the central nervous system (CNS), specifically the optic nerve and the spinal cord, with severe clinical manifestations, including optic neuritis (ON) and transverse myelitis. Initially, NMO was wrongly understood as a condition related to multiple sclerosis (MS), due to a few similar clinical and radiological features, until the discovery of the AQP4 antibody (NMO-IgG/AQP4-ab). Various etiological factors, such as genetic-environmental factors, medication, low levels of vitamins, and others, contribute to the initiation of NMO pathogenesis. The autoantibodies against AQP4 target the AQP4 channel at the blood–brain barrier (BBB) of the astrocyte end feet, which leads to high permeability or leakage of the BBB that causes more influx of AQP4-antibodies into the cerebrospinal fluid (CSF) of NMO patients. The binding of AQP4-IgG onto the AQP4 extracellular epitopes initiates astrocyte damage through complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). Thus, a membrane attack complex is formed due to complement cascade activation; the membrane attack complex targets the AQP4 channels in the astrocytes, leading to astrocyte cell damage, demyelination of neurons and oligodendrocytes, and neuroinflammation. The treatment of NMOSD could improve relapse symptoms, restore neurological functions, and alleviate immunosuppression. Corticosteroids, apheresis therapies, immunosuppressive drugs, and B cell inactivating and complement cascade blocking agents have been used to treat NMOSD. This review intends to provide all possible recent studies related to molecular mechanisms, clinical perspectives, and treatment methodologies of the disease, particularly focusing on recent developments in clinical criteria and therapeutic formulations.

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.

Therapeutic response to rituximab in seropositive neuromyelitis optica: Experience from a tertiary care center in South India

Objectives

Neuromyelitis optica (NMO) is a severe central nervous system demyelinating disease caused by autoantibodies to anti-aquaporin-4 immunoglobulin-G (AQP4-IgG). Rituximab, a monoclonal antibody targeting CD20 cells, is effective in neuromyelitis optica spectrum disorder (NMOSD) in several observational studies and small randomized controlled trials. However, this includes both AQP4-IgG antibody positive and negative cases. Whether rituximab is more effective in seropositive NMO is unknown. The aim of the study was to determine the efficacy of rituximab in seropositive NMO.

Materials and Methods

This single-center ambispective study with retrospective data collection and prospective follow-up included patients with NMOSD who were positive for AQP4-Ig-G and treated with rituximab. Efficacy outcomes assessed were annualized relapse rate (ARR), disability progression by expanded disability status scale (EDSS), very good outcome (defined as no relapse and an EDSS ≤3.5), and persistent antibody positivity. Safety was also monitored.

Results

Between June 2017 and December 2019, 15 AQP4-IgG-positive cases were identified. The mean (± SD) age was 36 ± 17.9 years and 73.3% were females. Transverse myelitis followed by optic neuritis was the most common presentations. Rituximab was initiated after a median period of 19-weeks from the disease onset. The mean number of rituximab doses received was 6.4 ± 2.3. After a mean follow-up duration of 107 ± 74.7 weeks from the first dose of rituximab, ARR significantly reduced from 0.5 ± 0.9 to 0.02 ± 0.08, difference 0.48 ± 0.86 (95% confidence intervals [CI], 0.0009-0.96; P = 0.05). The number of relapses also reduced significantly from 0.6 ± 0.8-0.07 ± 0.26 , a difference of 0.53 ± 0.91 (95% CI, 0.026-1.05; P = 0.041). EDSS also significantly reduced from 5.6 ± 2.5-3.3 ± 2.9 , a difference of 2.23 ± 2.36 (95% CI, 0.93-3.54; P = 0.003). Very good outcome was obtained in 73.3% (11 of 15); P = 0.002. AQP4-IgG remained positive in 66.7% (4 of 6) when repeated after a mean period of 149.5 ± 51.1 weeks after the first dose of rituximab. Neither pre-treatment ARR, EDSS, time to initiate rituximab, the total number of rituximab doses, or time to repeat AQP4-IgG were significantly associated with persistent antibody positivity. No serious adverse events were observed.

Conclusion

Rituximab exhibited high efficacy and good safety in seropositive NMO. Larger trials in this subgroup are warranted to confirm these findings.

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

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

It's not always an infection: Pyoderma gangrenosum of the urogenital tract in two patients with multiple sclerosis treated with rituximab

B-cell depleting therapies such as rituximab and ocrelizumab are widely used for the treatment of Multiple Sclerosis but have increased risks of adverse reactions compared to earlier MS therapies. One rarely reported reaction is pyoderma gangrenosum (PG), an inflammatory, ulcerative, skin disease of unclear etiology. Here we describe a male and female patient, each with Relapsing-Remitting Multiple Sclerosis, and both of whom developed PG while on rituximab. Both PG diagnoses were supported by persistent fever, biopsy reports of sterile neutrophilia, and leukocytosis in the absence of an identifiable infectious agent. The diagnoses were further confirmed by dramatic clinical improvement following initiation of high dose steroids and intravenous immunoglobulins, and discontinuation of rituximab.

Factors associated with the misdiagnosis of neuromyelitis optica spectrum disorder

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune condition that is associated with severe disability. Approximately 40% of individuals are misdiagnosed with multiple sclerosis (MS) or other diseases. We aimed to define factors that influence the misdiagnosis of people with NMOSD and provide strategies for reducing error rates.

METHODS

A retrospective study was performed involving all people with a confirmed diagnosis of NMOSD within a single academic institution. Comprehensive clinical timelines were constructed for each individual that included presenting symptoms, provider type and timing of evaluations, aquaporin 4-IgG (AQP4) results, and MRI scans. Two-sample comparisons of continuous and categorial variables were performed for people accurately diagnosed with NMOSD and those originally misdiagnosed with another medical condition. A subanalysis of only AQP4-IgG positive people was also performed.

RESULTS

The study cohort included 199 people fulfilling International Panel criteria for NMOSD with 71 people (62 female; mean age at first symptom presentation (standard deviation (SD)) = 32.8 years (y) (SD 16.1)) being initially misdiagnosed and 128 people (106 female; 41.14y (SD 15.41)) who were accurately diagnosed. Of the 199 people with NMOSD, 166 had a positive serostatus. Identified factors associated with misdiagnosis, regardless of AQP4-IgG serostatus, were the presence of protracted nausea/vomiting/hiccups without any accompanying neurological symptoms, 23 (32.4%) versus 16 (12.5%) (p = 0.001), a longer median (range) time to see a neuroimmunology specialist 4.2y (0.14-31.8) versus 0.5y (0.0-21.2) (p<0.0001), and a delay in acquiring an MRI study, 4.7y (0.0-27.3) versus 0.3y (0.0-20.2) (p<0.0001). A greater proportion of people misdiagnosed were identified with a negative live-cell based AQP4-IgG serum test result, 13/13 (100%) versus 22/114 (19.3%) (p<0.0001). Additionally, the mean (SD) time between a first negative and successive live-cell based AQP4-IgG positive test result was greater for people misdiagnosed with another condition, 3.9y (SD 5.0) versus 1.5y (SD 2.1) (p = 0.01). Although not significant between groups, a rash was also reported in 63/199 people with NMOSD, with 31/63 having an anti-nuclear antibody titer ≥ 1:160.

CONCLUSION

Defined factors can help guide both generalists and specialists in the pursuit of strategies aimed at efficiently diagnosing those with NMOSD such that effective care can be delivered.

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.

Anti-AQP4-IgG-positive Leigh syndrome: A case report and review of the literature

BACKGROUND

Leigh syndrome (LS; OMIM: 256000) is a progressive neurodegenerative disease caused by genetic mutations resulting in mitochondrial oxidative phosphorylation defects. The prognosis is poor, with most children dying before the age of 2 years. MT-ATP6 variants are the most common mitochondrial DNA mutations in LS. MT-ATP6 variant-induced LS may trigger autoimmunity, and immunotherapy might be effective. Here, we present the first pediatric case of anti-aquaporin 4 (AQP4)-IgG-positive LS caused by an MT-ATP6 variant.

CASE

A 1-year-old boy was hospitalized due to recurrent fever, cough, and developmental regression. Two months previously, he had developed reduced responses to stimulation and psychomotor retardation. After admission, his condition deteriorated and respiratory failure ensued. Magnetic resonance imaging of the brain showed symmetrical small patchy abnormal signals around the third ventricle, pons, and dorsal periaqueductal gray matter in the dorsal medulla. Laboratory tests revealed anti-AQP4-IgG antibodies. Anti-infection, immunoglobulin, and glucocorticoid therapy were administered for symptomatic treatment. Genetic testing revealed a de novo homogeneous pathogenic variant of MT-ATP6 (m.9176T > C, mutation ratio: 99.97%). The patient was diagnosed with anti-AQP4-IgG-positive LS, treated with "cocktail therapy" (vitamins B1, B2, C, and E, l-carnitine, and coenzyme Q10), and discharged after his condition improved. A literature review revealed that LS-induced mitochondrial defects can impact the immune system; hence, immunotherapy and early mitochondrial cocktail therapy may improve outcomes.

CONCLUSION

Anti-AQP4-IgG-positive LS is very rare. Patients with LS with the m.9176T  > C variant of MT-ATP6 may be susceptible to autoimmune damage of the central nervous system. Early cocktail therapy combined with immunotherapy may improve their prognosis.

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.

Paraneoplastic Neuromyelitis Optica Spectrum Disorder Related to Glucose-regulated Protein 78 (GRP78) Autoantibodies in a Patient with Lynch Syndrome-associated Colorectal Cancer

Neuromyelitis optica spectrum disorders have been previously reported in a paraneoplastic context, although there is no clear consensus on their pathogenesis. We herein report a case of aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder in a 64-year-old woman with colorectal cancer. She underwent tumor resection, resulting in serum aquaporin-4 antibody titers subsequently becoming negative. Serum samples were also positive for glucose-regulated protein 78 antibody, which has recently been suggested to be a novel factor in the disruption of the blood-brain barrier. Serological and pathological investigations in this case highlight the role and involvement of aquaporin-4 and glucose-regulated protein 78 antibodies in paraneoplastic conditions.

Treatment and Relapse Prevention of Typical and Atypical Optic Neuritis

Optic neuritis (ON) is an inflammatory condition involving the optic nerve. Several important typical and atypical ON variants are now recognized. Typical ON has a more favorable prognosis; it can be idiopathic or represent an early manifestation of demyelinating diseases, mostly multiple sclerosis (MS). The atypical spectrum includes entities such as antibody-driven ON associated with neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD), chronic/relapsing inflammatory optic neuropathy (CRION), and sarcoidosis-associated ON. Appropriate and timely diagnosis is essential to rapidly decide on the appropriate treatment, maximize visual recovery, and minimize recurrences. This review paper aims at presenting the currently available state-of-the-art treatment strategies for typical and atypical ON, both in the acute phase and in the long-term. Moreover, emerging therapeutic approaches and novel steps in the direction of achieving remyelination are discussed.

Disease Course and Outcomes in Patients With the Limited Form of Neuromyelitis Optica Spectrum Disorders and Negative AQP4-IgG Serology at Disease Onset: A Prospective Cohort Study

Background and Purpose

Patients presenting with clinical characteristics that are strongly suggestive of neuromyelitis optica spectrum disorders (NMOSD) have a high risk of developing definite NMOSD in the future. Little is known about the clinical course, treatment, and prognosis of these patients with likely NMOSD at disease onset.

Methods

This study prospectively recruited and visited 24 patients with the limited form of NMOSD (LF-NMOSD) at disease onset from November 2012 to June 2021. Their demographics, clinical course, longitudinal aquaporin-4 immunoglobulin G (AQP4-IgG) serology, MRI, therapeutic management, and outcome data were collected and analyzed.

Results

The onset age of the cohort was 38.1±12.0 years (mean±standard deviation). The median disease duration was 73.5 months (interquartile range=44.3–117.0 months), and the follow-up period was 54.2±23.8 months. At the end of the last visit, the final diagnosis was categorized into AQP4-IgG-seronegative NMOSD (n=16, 66.7%), AQP4-IgG-seropositive NMOSD (n=7, 29.2%), or multiple sclerosis (n=1, 4.2%). Seven of the 24 patients (29.2%) experienced conversion to AQP4-IgG seropositivity, and the interval from onset to this serological conversion was 37.9±21.9 months. Isolated/mixed area postrema syndrome (APS) was the predominant onset phenotype (37.5%). The patients with isolated/mixed APS onset showed a predilection for conversion to AQP4-IgG seropositivity. All patients experienced a multiphasic disease course, with immunosuppressive therapy reducing the incidence rates of clinical relapse and residual functional disability.

Conclusions

Definite NMOSD may be preceded by LF-NMOSD, particularly isolated/mixed APS. Intensive long-term follow-up and attack-prevention immunotherapeutic management is recommended in patients with LF-NMOSD.

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.

Glial Fibrillary Acidic Protein in Blood as a Disease Biomarker of Neuromyelitis Optica Spectrum Disorders

Glial fibrillary acidic protein (GFAP) is a type III intermediate filament protein found in astrocytes in the brain. Damaged astrocytes release GFAP into cerebrospinal fluid and blood. Thus, GFAP levels in these body fluids may reflect the disease state of neuromyelitis optica spectrum disorder (NMOSD), which includes astrocytopathy, characterized by pathogenic antibodies against aquaporin 4 located on astrocytes. Recently, single-molecule array technology that can detect these synaptic proteins in blood, even in the subfemtomolar range, has been developed. Emerging evidence suggests that GFAP protein is a strong biomarker candidate for NMOSD. This mini-review provides basic information about GFAP protein and innovative clinical data that show the potential clinical value of blood GFAP levels as a biomarker for NMOSD.

An Update on the Laboratory Diagnosis of Neuromyelitis Optica Spectrum Disorders

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disorder of the central nervous system that is specifically associated with demyelination of spinal cord and optic nerves. The discovery of specific autoantibody markers such as aquaporin-4 IgG and myelin oligodendrocyte glycoprotein IgG has led to several methodologies being developed and validated. There have been numerous investigations of the clinical and radiological presentations used in the clinical diagnosis of NMOSD. However, although various laboratory diagnostic techniques have been standardized and validated, a gold-standard test has yet to be finalized due to uncertain sensitivities and specificities of the methodologies. For this review, the literature was surveyed to compile the standardized laboratory techniques utilized for the differential diagnosis of NMOSD. Enzyme-linked immunosorbent assays enable screening of NMOSD, but they are considered less sensitive than cell-based assays (CBAs), which were found to be highly sensitive and specific. However, CBAs are laborious and prone to batch variations in their results, since the expression levels of protein need to be maintained and monitored meticulously. Standardizing point-of-care devices and peptide-based assays would make it possible to improve the turnaround time and accessibility of the test, especially in resource-poor settings.

A Case of Neuromyelitis Optica: Puerto Rican Woman with an Increased Time Lag to Diagnosis and a High Response to Eculizumab Therapy

A link between intractable hiccups, as the initial symptom, and a possible neuromyelitis optica spectrum disorder (NMOSD) diagnosis is confusing but vital and may not be made by health care providers (HCPs) if they are not aware of the 2015 NMOSD criteria. Early diagnosis and adequate treatment are essential to prevent disease progression. We report the case of a 46-year-old Puerto Rican female who presented intractable hiccups when she was 31 (in 2004). Almost 15 years passed since the initial symptom, and after two severe relapses, she received a formal NMOSD diagnosis in March 2019. Treatment started with rituximab 1000 mg IV in April 2019. However, a lack of response to treatment led to a switch to eculizumab therapy in August 2019. The patient had cervical and brain magnetic resonance imaging (MRI) conducted in June 2020, which depicted a remarkable decrease in swelling and hyperintensity within the cervical spinal cord with no enhancing lesions when compared with the first MRI from February 2019. In addition, the patient suffered no new relapses, an improvement regarding disability, and a reduction of the cervical spinal cord lesion size. Nonetheless, this substantial decrease does not occur on all NMOSD patients, but more awareness of the disease is needed, especially in Puerto Rico. This case illustrates the efficacy of eculizumab therapy and the importance of differentiating the clinical, histopathological, and neuroimaging characteristics that separate demyelinating autoimmune inflammatory disorders, such as NMOSD and multiple sclerosis (MS).

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].

Neuromyelitis optica spectrum disorders: from pathophysiology to therapeutic strategies

Neuromyelitis optica (NMO) is a chronic inflammatory autoimmune disease of the central nervous system (CNS) characterized by acute optic neuritis (ON) and transverse myelitis (TM). NMO is caused by a pathogenic serum IgG antibody against the water channel aquoporin 4 (AQP4) in the majority of patients. AQP4-antibody (AQP4-ab) presence is highly specific, and differentiates NMO from multiple sclerosis. It binds to AQP4 channels on astrocytes, triggering activation of the classical complement cascade, causing granulocyte, eosinophil, and lymphocyte infiltration, culminating in injury first to astrocyte, then oligodendrocytes followed by demyelination and neuronal loss. NMO spectrum disorder (NMOSD) has recently been defined and stratified based on AQP4-ab serology status. Most NMOSD patients experience severe relapses leading to permanent neurologic disability, making suppression of relapse frequency and severity, the primary objective in disease management. The most common treatments used for relapses are steroids and plasma exchange.Currently, long-term NMOSD relapse prevention includes off-label use of immunosuppressants, particularly rituximab. In the last 2 years however, three pivotal clinical trials have expanded the spectrum of drugs available for NMOSD patients. Phase III studies have shown significant relapse reduction compared to placebo in AQP4-ab-positive patients treated with satralizumab, an interleukin-6 receptor (IL-6R) inhibitor, inebilizumab, an antibody against CD19⁺ B cells; and eculizumab, an antibody blocking the C5 component of complement. In light of the new evidence on NMOSD pathophysiology and of preliminary results from ongoing trials with new drugs, we present this descriptive review, highlighting promising treatment modalities as well as auspicious preclinical and clinical studies.

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.

Neuromyelitis Optica Spectrum Disorders (NMOSD) and Connective Tissue Disease (CTD): an Update for the Rheumatologist

PURPOSE OF REVIEW

To review the pathophysiology, presentation, and treatment of neuromyelitis optica spectrum disorder (NMOSD) and its association with systemic lupus erythematosus (SLE) and Sjogren's syndrome (SS).

RECENT FINDINGS

NMOSD is an autoimmune disorder of the central nervous system that primarily targets astrocytes. Although the prevalence is unknown, the coexistence of NMOSD and SLE/SS is well-recognized. Patients with both NMOSD and SLE or SS require may require unique approaches to diagnosis and management. Coexistence of NMOSD and SLE/SS is important for the rheumatologist and neurologist to be able to recognize. For the rheumatologist, NMOSD and its neurologic symptoms represent a distinct disease process from neurologic complications of the patient's underlying connective tissue disease, and it requires distinct acute and chronic management. For the neurologist, the coexistence of SLE and SS can help to establish a diagnosis of NMOSD, or in some situations, the development of neurologic symptoms secondary to NMOSD can lead to the diagnosis of connective tissue disease.

[Aquaporin 4 antibody-positive neuromyelitis optica spectrum disorders and myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis. A brief review]

Aquaporin 4 (AQP4) immunoglobulin (Ig)G-associated neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein immunoglobulin (Ig)G-associated encephalomyelitis (MOG-EM, also termed MOG antibody-associated disease, MOGAD) are important autoimmune differential diagnoses of multiple sclerosis (MS), which differ from MS with respect to optimum treatment and prognosis. AQP4 IgG-positive NMOSD take a relapsing course in virtually all cases and MOG-EM in at least 80% of adult cases. Both diseases can quickly lead to permanent disability if left untreated, although MOG-EM is associated with a better overall long-term prognosis. Antibody testing must be carried out by means of so-called cell-based assays. A number of red flags have been defined that must be checked prior to making a diagnosis of NMOSD or MOG-EM. Acute attacks are treated using high-dose glucocorticoids and plasma exchange or immunoadsorption. Rituximab and other immunosuppressants are used off-label for attack prevention. Recently, eculizumab, a C5 complement inhibitor, has been approved in the European Union (EU) for the treatment of patients with AQP4 IgG-positive NMOSD. This article gives a brief overview of the clinical and paraclinical features, pathology, treatment and prognosis of these rare disorders.

Recent Advances in Neuromyelitis Optica Spectrum Disorder: Pathogenesis, Mechanisms and Potential Treatments

Neuromyelitis optica spectrum disorder (NMOSD) is an acute or subacute demyelinating disease that affects mainly the optic nerve and spinal cord. A major proportion of NMOSD cases have a relationship with autoimmunity to aquaporin 4 (AQP4) found on the central nervous system. NMOSD can occur repeatedly, causing symptoms such as decreased vision and weakness of limbs. The main goal of current therapy is to relieve acute symptoms and prevent recurrence of the disease. Without timely and appropriate treatment, the recurrence and disability rates are high. In the present work, we review recent advances in the diagnosis and treatment of patients with NMOSD, as well as the pathogenesis and mechanisms of AQP4-IgG-seropositive NMOSD.

Efficacy of rituximab in the treatment of neuromyelitis optica spectrum disorders: An update systematic review and meta -analysis

BACKGROUND

Neuromyelitis optica spectrum disorders (NMOSD) is an autoimmune astrocyte disease that mainly affects the optic nerve and spinal cord resulting in blindness or paralysis. Rituximab (RTX) is a chimeric monoclonal antibody directed against the surface antigen of CD20 on B lymphocytes and is an emerging treatment option in NMOSD. The present review aimed to conduct an update systematic review and meta-analysis for the efficacy of RTX in the treatment of NMOSD and analyze main factors affecting the efficacy of RTX.

METHODS

The following Medical Subject Heading (MeSH) and related entry terms are used to search English literature in PubMed, MEDLINE and CENTRAL databases, respectively. MeSH include: Neuromyelitis optic and Rituximab; entry terms include: NMO Spectrum Disorder, NMO Spectrum Disorders, Neuromyelitis Optica (NMO) Spectrum Disorder, Neuromyelitis Optica Spectrum Disorders, Devic Neuromyelitis Optica, Neuromyelitis Optica, Devic, Devic's Disease, Devic Syndrome, Devic's Neuromyelitis Optica, Neuromyelitis Optica (NMO) Spectrum Disorders, CD20 Antibody, Rituximab CD20 Antibody, Mabthera, IDEC-C2B8 Antibody, GP2013, Rituxan; (note: literature retrieval operators "AND" "OR" "NOT" are used to link MeSH with Entry Terms.) 54 studies were included in this systematic review and 29 studies were included in meta-analysis. The main efficacy indicators were the difference of the expanded disability status scale (EDSS) and annualized relapse rate (ARR) between before and after rituximab treatments.

RESULTS

In 29 studies involving 732 patients (643 women, 84 men, 5 with unknown gender), the EDSS and ARR were reduced by an average of -0.57 (95%CI, -0.69 to -0.44), -1.57 (95%CI, -1.78 to -1.35), respectively.

CONCLUSION

Our systematic review and update meta-analysis provide new evidences that RTX can effectively improve disability and reduce ARR ratio.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Different Targets of Monoclonal Antibodies in Neuromyelitis Optica Spectrum Disorders: A Meta-Analysis Evidenced From Randomized Controlled Trials

Background: Neuromyelitis optica spectrum disorder (NMOSD), an autoimmune inflammatory disorder of the central nervous system, often leads to vision loss or paralysis. This meta-analysis focused on the assessment of the monoclonal antibody therapy in NMOSD and compared different targets of monoclonal antibodies with each other in terms of efficacy and safety outcomes.

Method: We searched through the databases of MEDLINE, EMBASE, Central Register of Controlled Trials (CENTRAL), and clinicaltrials.gov for randomized controlled trials (RCTs) evaluating monoclonal antibody therapy in NMOSD up to April 2020.

Results: We identified seven randomized controlled trials (RCTs), including 775 patients (monoclonal antibody group, n = 485 and placebo group, n = 290). Monoclonal antibody therapy decreased relapse risk (RR 0.33, 95% CI 0.21–0.52, P < 0.00001), annualized relapse rate (ARR) (mean −0.28, 95% CI −0.35−0.20, P < 0.00001), expanded disability status scale score (EDSS) (mean −0.19, 95% CI −0.32−0.07, P = 0.002) and serious adverse events (RR 0.78, 95% CI 0.61–1.00, P = 0.05). However, we did not observe any significant difference in terms of adverse events or mortality. Further, the subgroup analysis demonstrated that the anti-complement protein C5 monoclonal antibody (eculizumab) might have a lower relapse risk (RR 0.07, 95% CI 0.02–0.23, P < 0.0001) in the AQP4 seropositive patients, and anti-interleukin-6 receptor monoclonal antibodies (satralizumab and tocilizumab) showed decreased EDSS score (mean −0.17, 95% CI −0.31−0.02, P = 0.02) more effectively than other monoclonal antibodies.

Conclusions: Monoclonal antibodies were effective and safe in NMOSD. Different targets of monoclonal antibodies might have their own advantages.

Efficacy for the Annual Relapse Rate after the Immunosuppressive Therapy in Patients Associated with Anti-AQP4 or Anti-MOG Antibody-Positive Optic Neuritis

Purpose

Although oral prednisolone is the first-line treatment for preventing recurrent optic neuritis (ON) after the completion of acute-phase treatment, especially anti-aquaporin 4 (AQP4) antibody-positive ON, and anti-myelin oligodendrocyte glycoprotein (MOG) antibody-positive ON, some patients experience relapses. Immunosuppressants could be effective in reducing the recurrence rate for neuromyelitis optica spectrum disorder and MOG antibody-related diseases, but there have been few studies addressing this issue focusing on the changes in ophthalmic parameters. The objective of the study was to analyze the impact of off-label uses of immunosuppressants to reduce recurrent ON.

Design

Retrospective observational study, clinical case series.

Methods

We reviewed the medical charts of 11 cases (22 eyes) who underwent immunosuppressive therapy in Kobe University Hospital and compared the annualized relapse rate (ARR) before and after immunosuppressive therapy. We also evaluated the dosage of prednisolone, complications of immunosuppressants, and other visual functional ophthalmologic parameters.

Results

Eleven cases in total had AQP4 antibody (9 cases) and/or MOG antibody (3 cases). One case was double positive for these antibodies. Nine patients received azathioprine and two received mycophenolate mofetil as an initial immunosuppressive therapy. The median duration of immunosuppressant treatment was 2.8 years. The median ON ARR before immunosuppressive therapy was 0.33, and this decreased significantly to 0 after the therapy (p = 0.02). The dose of prednisolone was reduced from 17.8 ± 7.1 mg/day before to 5.8 ± 2.2 mg/day after immunosuppressive therapy (p < 0.01). Although two patients presented with mild elevation of liver enzymes and nausea, all patients were able to continue taking the immunosuppressants.

Conclusions

Immunosuppressants can potentially decrease relapses and steroid dosage in patients with anti-AQP4 or MOG antibody-positive ON without severe adverse events and the exacerbation of visual acuities.

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.

Advances in the Treatment of Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is a rare, relapsing-remitting neuroinflammatory disorder of the central nervous system. Advances in the understanding of NMOSD pathogenesis and identification of the NMO-specific pathogenic anti-AQP4 autoantibody have led to the development of highly effective disease-modifying strategies. Five placebo-controlled, randomized trials for NMOSD have been successfully completed as of 2020. These trials support the efficacy of rituximab and tocilizumab and led to the FDA approval of eculizumab, satralizumab and inebilizumab for NMOSD. Our review provides an update on these evidence-based disease-modifying therapies and discussed the treatment of acute relapses in NMOSD.