NMO-IgG in the diagnosis of neuromyelitis optica

The absence of antibodies in longitudinally extensive transverse myelitis may predict a more favourable prognosis

BACKGROUND

Isolated first episodes of longitudinally extensive transverse myelitis (LETM) have typically been associated with neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). However, in some cases, serological testing and screening for other aetiologies are negative, a condition referred to as double seronegative longitudinally extensive transverse myelitis (dsLETM).

OBJECTIVE

The objective of this study was to evaluate comparative outcomes of dsLETM, MOGAD-LETM and NMOSD-LETM.

METHODS

Cohort study of LETM cases seen in the UK NMOSD Highly Specialised Service between January 2008 and March 2022.

RESULTS

LETM = 87 cases were identified (median onset age = 46 years (15-85); median follow-up = 46 months (1-144); 47% NMOSD-LETM = 41 (aquaporin-4 antibodies (AQP4-IgG) positive = 36), 20% MOGAD-LETM = 17 and 33% dsLETM = 29). Despite similar Expanded Disability Status Scale (EDSS) at nadir, last EDSS was higher in AQP4-IgG and seronegative NMOSD-LETM (sNMOSD) (p = 0.006). Relapses were less common in dsLETM compared to AQP4-IgG NMOSD-LETM and sNMOSD-LETM (19% vs 60% vs 100%; p = 0.001). Poor prognosis could be predicted by AQP4-IgG (odds ratio (OR) = 38.86 (95% confidence interval (CI) = 1.36-1112.86); p = 0.03) and EDSS 3 months after onset (OR = 65.85 (95% CI = 3.65-1188.60); p = 0.005).

CONCLUSION

dsLETM remains clinically challenging and difficult to classify with existing nosological terminology. Despite a similar EDSS at nadir, patients with dsLETM relapsed less and had a better long-term prognosis than NMOSD-LETM.

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.

Clinical significance of anti-SSA/Ro antibody in Neuromyelitis optica spectrum disorders

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system (CNS), also described as CNS autoimmune astrocytopathy, due to the production of pathogenic antibodies against aquaporin-4 (AQP4) expressed on the foot of astrocytes. NMOSD coexists with autoimmune diseases and related autoantibodies [anti-Sjogren's syndrome A (anti-SSA)/Ro antibody, anti-Sjogren's syndrome B (anti-SSB)/La antibody, anti-nuclear (anti-ANA) antibodies, anti-double-stranded DNA (anti-dsDNA) antibody, anti-thyroglobulin antibody, and anti-thyroid peroxidase antibody].

OBJECTIVES

No precise conclusion has been drawn on the role of the anti-SSA/Ro antibody in NMOSD. Therefore, the aim of this work was to evaluate whether the anti-SSA/Ro antibody has an impact on the clinical manifestation or prognosis of NMOSD.

METHODS

Data were retrospectively collected from 102 patients with NMOSD diagnosed by experienced neurologists. The study population was divided into two groups based on the serum anti-SSA/Ro antibody status: NMOSD with or without anti-SSA/Ro antibody. The clinical, neuroimaging and laboratory parameters were compared between the two groups, including the neurological symptoms, MRI results, frequency of systemic autoantibodies, Expanded Disability Status Scale (EDSS), and NMOSD relapse rate. The EDSS and relapse were applied as measures of the NMOSD patient prognostic value. Cox regression analysis was used to evaluate the prognostic impact of anti-SSA/Ro antibody on NMOSD.

RESULTS

Among the 102 NMOSD patients, striking differences were observed in the positive rate of AQP4-IgG (89.2% vs. 72.3%, p = 0.046) between those patients with and without the anti-SSA/Ro antibody. In addition, NMOSD patients with anti-SSA/Ro antibody showed the presence of more frequent anti-ANA antibodies (p = 0.002), anti-SSB/La antibody (p < 0.001), anti-dsDNA antibody (p < 0.002), Sjogren's syndrome (SS, p < 0.001) and systemic lupus erythematosus (SLE, p = 0.045). Univariate and multivariate Cox regression analysis were performed to confirm that the anti-SSA/Ro antibody affected the EDSS score and the relapse of NMOSD patients. The analysis of the survival curve revealed that the EDSS score in the NMOSD patients positive for the anti-SSA/Ro antibody reached 4.0 (p = 0.035) and relapsed (p = 0.039) earlier than in the negative group.

CONCLUSION

The anti-SSA/Ro antibody could be associated with disease activity and severe disability in NMOSD.

Clinical risk factors and prognostic model for idiopathic inflammatory demyelinating diseases after haploidentical hematopoietic stem cell transplantation in patients with hematological malignancies

Idiopathic inflammatory demyelinating diseases (IIDDs) of the central nervous system (CNS) are rare but serious neurological complications of haploidentical hematopoietic stem cell transplantation (haplo-HSCT). However, the risk factors and a method to predict the prognosis of post-transplantation CNS IIDDs are not available. This retrospective study first reviewed data from 4532 patients who received haplo-HSCT during 2008-2019 in our center, and 184 patients (4.1%) with IIDDs after haplo-HSCT were identified. Grades II to IV acute graft-versus-host disease (aGVHD) (p < 0.001) and chronic GVHD (cGVHD) (p = 0.009) were identified as risk factors for developing IIDDs after haplo-HSCT. We then divided the 184 IIDD patients into a derivation cohort and validation cohort due to transplantation time to develop and validate a model for predicting the prognosis of IIDDs. In the multivariate analysis of the derivation cohort, four candidate predictors were entered into the final prognostic model: cytomegalovirus (CMV) infection, Epstein-Barr virus (EBV) infection, IgG synthesis (IgG-syn) and spinal cord lesions. The prognostic model had an area under the receiver operating characteristic curve of 0.864 (95% CI: 0.803-0.925) in the internal validation cohort and 0.871 (95% CI: 0.806-0.931) in the external validation cohort. The calibration plots showed a high agreement between the predicted and observed outcomes. Decision curve analysis indicated that IIDD patients could benefit from the clinical application of the prognostic model. The identification of IIDD patients after allo-HSCT who have a poor prognosis might allow timely treatment and improve patient survival and outcomes.

The Glymphatic System (En)during Inflammation

The glymphatic system is a fluid-transport system that accesses all regions of the brain. It facilitates the exchange of cerebrospinal fluid and interstitial fluid and clears waste from the metabolically active brain. Astrocytic endfeet and their dense expression of the aquaporin-4 water channels promote fluid exchange between the perivascular spaces and the neuropil. Cerebrospinal and interstitial fluids are together transported back to the vascular compartment by meningeal and cervical lymphatic vessels. Multiple lines of work show that neurological diseases in general impair glymphatic fluid transport. Insofar as the glymphatic system plays a pseudo-lymphatic role in the central nervous system, it is poised to play a role in neuroinflammation. In this review, we discuss how the association of the glymphatic system with the meningeal lymphatic vessel calls for a renewal of established concepts on the CNS as an immune-privileged site. We also discuss potential approaches to target the glymphatic system to combat neuroinflammation.

The Emerging Role of Microglia in Neuromyelitis Optica

Neuromyelitis optica (NMO) is an autoantibody-triggered neuro-inflammatory disease which preferentially attacks the spinal cord and optic nerve. Its defining autoantibody is specific for the water channel protein, aquaporin-4 (AQP4), which primarily is localized at the end-feet of astrocytes. Histopathology studies of early NMO lesions demonstrated prominent activation of microglia, the resident immune sentinels of the central nervous system (CNS). Significant microglial reactivity is also observed in NMO animal models induced by introducing AQP4-IgG into the CNS. Here we review the potential roles for microglial activation in human NMO patients as well as different animal models of NMO. We will focus primarily on the molecular mechanisms underlying microglial function and microglia-astrocyte interaction in NMO pathogenesis. Understanding the role of microglia in NMO pathology may yield novel therapeutic approaches for this disease.

The S1P-S1PR Axis in Neurological Disorders-Insights into Current and Future Therapeutic Perspectives

Sphingosine 1-phosphate (S1P), derived from membrane sphingolipids, is a pleiotropic bioactive lipid mediator capable of evoking complex immune phenomena. Studies have highlighted its importance regarding intracellular signaling cascades as well as membrane-bound S1P receptor (S1PR) engagement in various clinical conditions. In neurological disorders, the S1P–S1PR axis is acknowledged in neurodegenerative, neuroinflammatory, and cerebrovascular disorders. Modulators of S1P signaling have enabled an immense insight into fundamental pathological pathways, which were pivotal in identifying and improving the treatment of human diseases. However, its intricate molecular signaling pathways initiated upon receptor ligation are still poorly elucidated. In this review, the authors highlight the current evidence for S1P signaling in neurodegenerative and neuroinflammatory disorders as well as stroke and present an array of drugs targeting the S1P signaling pathway, which are being tested in clinical trials. Further insights on how the S1P–S1PR axis orchestrates disease initiation, progression, and recovery may hold a remarkable potential regarding therapeutic options in these neurological disorders.

Identification of geraldol as an inhibitor of aquaporin‑4 binding by NMO‑IgG

Neuromyelitis optica (NMO) is a severe neurological demyelinating autoimmune disease that affects the optic nerves and spinal cord. There is currently no effective cure or therapy. Aquaporin-4 (AQP4) is a known target of the autoimmune antibody NMO-IgG. Therefore, binding of NMO-IgG to AQP4, and subsequent activation of antibody-mediated and complement-dependent cytotoxicity (CDC), are thought to underlie the pathogenesis of NMO. In the present study, a cell-based high-throughput screening approach was developed to identify molecular inhibitors of NMO-IgG binding to AQP4. Using this approach, extracts from the herb Petroselinum crispum were shown to have inhibitory effects on NMO-IgG binding to AQP4, and the natural compound geraldol was purified from the herb extracts. Analytical high performance liquid chromatography, electrospray ionization-mass spectrometry and nuclear magnetic resonance analyses confirmed the identity of the isolated compound as geraldol, a flavonoid. Geraldol effectively blocked binding of NMO-IgG to AQP4 in immunofluorescence assays and decreased CDC in NMO-IgG/complement-treated FRTL-AQP4 cells and primary astrocytes. Geraldol exhibited low cytotoxicity, with no effect on proliferation or apoptosis of FRTL-AQP4 cells and primary astrocytes. Permeability assays indicated that geraldol did not alter the water transport function of AQP4 in either cell system. The present study suggests the potential therapeutic value of geraldol for NMO drug development.

Epidemiology of Pediatric NMOSD in Germany and Austria

Background: Neuromyelitis optica spectrum disorders (NMOSD) are severe inflammatory demyelinating disorders of the central nervous system mainly characterized by recurrent episodes of uni- or bilateral optic neuritis (ON), transverse myelitis (TM) and brainstem syndromes (BS). The majority of adult patients has serum antibodies directed against the water channel protein aquaporin 4 (AQP4-abs). In pediatric patients, AQP4-abs are less, while antibodies against myelin oligodendrocyte glycoprotein (MOG-abs) are more frequently detectable than in adults. Some children with NMOSD have neither AQP4- nor MOG-ab (double-seronegative).

Objective: Evaluation of epidemiological data regarding incidence and prevalence of pediatric NMOSD in Germany and Austria.

Methods: We recruited pediatric NMOSD patients between 1 March 2017 and 28 February 2019 with five different tools: (1) ESPED (Surveillance Unit for Rare Pediatric Disorders in Germany), (2) ESNEK (Surveillance for Rare Neurological Disorders during Childhood), (3) pediatric neurology working group within the Austrian Society of Pediatrics and Adolescent Medicine, (4) BIOMARKER Study and (5) NEMOS (Neuromyelitis optica Study Group). We requested data regarding clinical symptoms, antibody status, therapy regimen and response via a standardized questionnaire.

Results: During the 2-year recruitment period, 46 (both incidental and prevalent) patients with a suspected diagnosis of NMOSD were brought to our attention. Twenty-two of these patients did not fulfill the inclusion criteria. Of the remaining 24 children, 22 had a median age at onset of 11 (range 3–17) years and 16/22 were female (72.7%) (no data in two patients). Sixteen of 24 patients were AQP4-ab positive (67%), 4/24 MOG-ab positive (16.7%), three children were double-seronegative and in one patient no antibody testing was done. We calculated an incidence rate of 0.022 per 100,000 person-years for Germany, while there was no incidental case in Austria during the recruitment period. The prevalence rate was 0.147 and 0.267 per 100,000 persons in Germany and Austria, respectively.

Conclusion: Pediatric NMOSD, with and without associated antibodies, are very rare even considering the different limitations of our study. An unexpected finding was that a considerable proportion of patients was tested neither for AQP4- nor MOG-abs during diagnostic work-up, which should prompt to establish and disseminate appropriate guidelines.

Isolated Area Postrema Syndrome Presenting as Intractable Nausea and Vomiting

Neuromyelitis optica (NMO) is a disease of central nervous system, characterized by demyelination and axonal damage mostly involving optic nerves and spinal cord. Usually these patients present with symptoms related to optic neuritis or myelitis with a typical relapsing course. Some patients present with less common symptoms involving brain stem like nausea and vomiting, especially those involving area postrema (AP) located in dorsal medulla. International panel for NMO diagnosis revised criteria in 2015 and came up with a unifying term NMO spectrum disorders (NMOSD) instead of NMO. Patients with NMO having AP involvement are grouped under area postrema syndrome (APS). Usually patients with AP symptoms also have neurological symptoms upon presentation. Here we present a rare case of an NMO who presented with isolated APS with no other neurological symptoms.

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

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

General anaesthesia for caesarean section in a patient with neuromyelitis optica spectrum disorder (NMOSD)

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We report the anaesthetic management of a patient with pre-existing NMOSD undergoing a caesarean delivery.

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Multidisciplinary collaboration and careful patient counselling were essential to optimize maternal and foetal outcomes.

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The use of neuromuscular monitoring and sugammadex reversal might play an important role in anesthetic management of patients with NMOSD.

Introduction

Neuromyelitis optica spectrum disorder (NMOSD) is a rare demyelinating disorder affecting the spinal cord and optic nerves. The anesthetic management in parturient women with NMOSD are controversial and remains challenging.

Presentation of case

A 35-year-old G2P1 woman at 36 weeks of gestation with NMOSD presented for pre-anesthesia assessment prior to caesarean section. Her NMOSD had been diagnosed four years previously and was treated with intravenous methylprednisolone (IVMP) and plasma exchange (PLEX). She underwent general anesthesia without developing adverse respiratory events or signs and symptoms of muscle weakness.

Discussion

Both neuraxial and general anaesthesia for NMOSD have been described in previous case reports. Risk factors of general anesthesia in pregnancy with NMOSD must be weighed against the likely risk of NMOSD relapse and the potential deteriorating neurological symptoms after neuraxial anesthesia.

Conclusion

A multidisciplinary collaboration together with careful anesthetic consideration is required for the anesthetic and perioperative management of these patients.

Updated diagnostic criteria for neuromyelitis optica spectrum disorder: Similar outcomes of previously separate cohorts

Background

The specificity of the aquaporin-4 antibody to predict recurrent inflammatory central nervous system disease has led to the design of the 2015 neuromyelitis optica spectrum disorder criteria which capture all aquaporin-4 antibody seropositive patients.

Objective

The purpose of this study was to compare treatment outcomes in aquaporin-4 antibody seropositive patients who met the previous 2006 clinical criteria for neuromyelitis optica with patients who meet the 2015 neuromyelitis optica spectrum disorder criteria.

Methods

The study involved a three-center retrospective chart review of clinical outcomes among aquaporin-4 patients diagnosed with neuromyelitis optica and neuromyelitis optica spectrum disorder.

Results

Hazard ratios of relapse during immunosuppressive therapy, relative to pre-therapy, were not significantly different for patients who met the 2006 criteria of neuromyelitis optica versus the 2015 neuromyelitis optica spectrum disorder criteria among those treated with azathioprine ( p = 0.24), mycophenolate mofetil ( p = 0.63), or rituximab ( p = 0.97).

Conclusion

Reductions in the hazard of relapse during treatment with immunosuppressive therapies, relative to average pre-treatment, were not different for aquaporin-4 antibody seropositive patients categorized using the 2006 criteria of neuromyelitis optica and the 2015 neuromyelitis optica spectrum disorder criteria. These therapeutic findings support the design of the 2015 neuromyelitis optica spectrum disorder criteria which capture all aquaporin-4 antibody seropositive patients.

Neuromyelitis optica spectrum disorders with and without connective tissue disorders

BACKGROUND

Neuromyelitis optica spectrum disorders (NMOSD) often coexist with connective tissue disorders (CTD). The aim of this study was to investigate and compare the features of NMOSD with and without CTD.

METHODS

NMOSD patients with (n = 18) and without CTD (n = 39) were enrolled, and the clinical, laboratory, and magnetic resonance imaging (MRI) features of the two groups were assessed.

RESULTS

Most of the demographic and clinical features examined were similar between NMOSD patients with and without CTD. Serum immunoglobulin G (IgG), percentage of γ-globulin and seropositivity for several other autoantibodies were significantly elevated in NMOSD patients with CTD (P < 0.05). NMOSD with CTD was marked by longer spinal cord lesions and a lower frequency of short transverse myelitis (TM) than NMOSD without CTD (P < 0.05). NMOSD with CTD also featured more T1 hypointensity and T2 bright spotty lesions (BSLs) on MRI than NMOSD without CTD (P = 0.001 and 0.011, respectively). There were no other differences in laboratory, MRI and clinical characteristics between different NMOSD subtypes.

CONCLUSIONS

A few characteristics differed between NMOSD with and without CTD. NMOSD patients with CTD had higher serum IgG, longer spinal cord lesions, a lower frequency of short TM and more T1 hypointensity and T2 BSLs on spinal MRI than NMOSD patients without CTD.

Prevalence of anti-aquaporin 4 antibody in a diagnostic cohort of patients being investigated for possible neuromyelitis optica spectrum disorder in Western Australia

OBJECTIVE

To evaluate the prevalence of anti-AQP4 antibody in serum and CSF samples from patients being investigated for possible neuromyelitis optica spectrum disorder (NMOSD) referred to the PathWest State reference laboratory using a sensitive cell-based assay (CBA).

BACKGROUND

NMOSD is an inflammatory CNS disease distinct from MS, which is relatively rare in Western countries. A proportion of patients with NMOSD have detectable serum IgG antibodies that target the water channel aquaporin-4 (AQP4-IgG), but the frequency varies in different populations studied and according to the assay method employed.

METHODS

Sera or CSF from a diagnostic cohort of 196 consecutive patients with possible NMOSD which had previously been screened by indirect immunofluorescence (IIF) on primate cerebellum were re-tested for AQP4-IgG reactivity to the M1 and M23 isoforms of AQP4 using a commercial CBA. A control group of 205 patients with definite MS was also included in the study.

RESULTS

Of the 196 patients, only 5 sera were AQP4-IgG positive, representing 2.6% of patients in the diagnostic cohort. All 5 AQP4-IgG positive patients fulfilled the 2015 revised diagnostic criteria for NMOSD and were females of varied ethnic origins, 4 of whom had longitudinally extensive transverse myelitis. The CBA confirmed AQP4-IgG positivity in the four patients previously reported as positive by IIF, and an additional patient with NMOSD who had previously been diagnosed as MS was also identified. None of the 205 MS sera were AQP4-IgG positive.

CONCLUSIONS

Our study confirms the utility and greater reliability of the M1/M23 CBA for detecting AQP4-IgG in patients with possible NMOSD, and indicates a prevalence of seropositive NMOSD in the Western Australian population similar to that in other Western populations.

Association between Sun Exposure, Vitamin D Intake, Serum Vitamin D Level, and Immunoglobulin G Level in Patients with Neuromyelitis Optica Spectrum Disorder

Background:

Neuromyelitis optica spectrum disorder (NMOSD) is a central nervous system inflammatory disorder in which immunoglobulin G (IgG) autoantibodies possibly play a pathogenic role against the aquaporin-4 water channel protein. Vitamin D may modulate B-cell function and decrease the IgG synthesis and may play a role in NMOSD as a crucial factor. The aim of this study was to investigate the relation between Vitamin D intakes from food, Vitamin D intake from sunlight exposure, blood Vitamin D levels, and IgG-neuromyelitis optica (NMO) level in serum of patients with NMOSD and NMO.

Method:

In this cross-sectional study, food Frequency Questionnaires (FFQ) and Sun Exposure Questionnaire (SEQ) were completed to evaluate of vitamin D intakes from food and sun light exposure. Moreover, serum levels of 25(OH) vitamin D3 and IgG-NMO were assessed in patients with NMOSD and NMO.

Results:

We assessed IgG-NMO levels in 29 patients with NMOSD that nine patients (n = 31%) were positive and for the rest it was negative. Sunlight exposure scale (P = 0.01) and 25(OH) D3 (P = 0.04) in IgG-NMO-negative patients were significantly more than patients with positive IgG-NMO. Age, gender, and latitude were not confounder variables. A positive significant correlation was observed between the sun exposure scale and serum levels of 25(OH) D3 in all participants (r = 0.747, P ≤ 0.001).

Conclusions:

Physiological variation in Vitamin D may apply a significant effect on IgG-NMO synthesis in patients with NMO. Vitamin D may have significant role in pathogenesis of NMOSD and NMO.

MRI Features of Aquaporin-4 Antibody-Positive Longitudinally Extensive Transverse Myelitis: Insights into the Diagnosis of Neuromyelitis Optica Spectrum Disorders

BACKGROUND AND PURPOSE

Longitudinally extensive transverse myelitis is a well-documented spinal manifestation of neuromyelitis optica spectrum disorders, however, other forms of nontumorous myelopathy can also manifest as longitudinally extensive transverse myelitis. Our aim was to evaluate the MR imaging features of aquaporin-4 antibody-positive longitudinally extensive transverse myelitis, which is strongly associated with neuromyelitis optica spectrum disorders.

MATERIALS AND METHODS

We evaluated cervicomedullary junction involvement, cord expansion ratios, bright spotty lesions, the number of involved segments, skipped lesions, enhancement patterns, and axial distribution patterns using spinal MR imaging of 41 patients with longitudinally extensive transverse myelitis who underwent aquaporin-4 antibody testing. Univariate logistic regression analysis was performed to identify factors associated with aquaporin-4 antibody seropositivity, which were then used to develop a scoring system for diagnosing aquaporin-4 antibody-positive longitudinally extensive transverse myelitis. Interrater reliability for cord expansion ratio measurement and bright spotty lesions was determined using intraclass correlation coefficients and κ values, respectively.

RESULTS

Fifteen patients with longitudinally extensive transverse myelitis were aquaporin-4 antibody-positive. Sex (female), cervicomedullary junction involvement, a cord expansion ratio of >1.4, and bright spotty lesions were significantly associated with aquaporin-4 antibody seropositivity. The sensitivity and specificity of the scoring system were 73.3% and 96.2%, respectively. The interclass correlation value for the cord expansion ratio was 0.78, and the κ value for bright spotty lesions was 0.61.

CONCLUSIONS

Our scoring system, based on cervicomedullary junction involvement, higher cord expansion ratio, bright spotty lesions, and female sex, can facilitate the timely diagnosis of neuromyelitis optica spectrum disorders.

Inositol 1,4,5-trisphosphate receptor type 1 autoantibodies in paraneoplastic and non-paraneoplastic peripheral neuropathy

BACKGROUND

Recently, we described a novel autoantibody, anti-Sj/ITPR1-IgG, that targets the inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) in patients with cerebellar ataxia. However, ITPR1 is expressed not only by Purkinje cells but also in the anterior horn of the spinal cord, in the substantia gelatinosa and in the motor, sensory (including the dorsal root ganglia) and autonomic peripheral nervous system, suggesting that the clinical spectrum associated with autoimmunity to ITPR1 may be broader than initially thought. Here we report on serum autoantibodies to ITPR1 (up to 1:15,000) in three patients with (radiculo)polyneuropathy, which in two cases was associated with cancer (ITPR1-expressing adenocarcinoma of the lung, multiple myeloma), suggesting a paraneoplastic aetiology.

METHODS

Serological and other immunological studies, and retrospective analysis of patient records.

RESULTS

The clinical findings comprised motor, sensory (including severe pain) and autonomic symptoms. While one patient presented with subacute symptoms mimicking Guillain-Barré syndrome (GBS), the symptoms progressed slowly in two other patients. Electrophysiology revealed delayed F waves; a decrease in motor and sensory action potentials and conduction velocities; delayed motor latencies; signs of denervation, indicating sensorimotor radiculopolyneuropathy of the mixed type; and no conduction blocks. ITPR1-IgG belonged to the complement-activating IgG1 subclass in the severely affected patient but exclusively to the IgG2 subclass in the two more mildly affected patients. Cerebrospinal fluid ITPR1-IgG was found to be of predominantly extrathecal origin. A ³H-thymidine-based proliferation assay confirmed the presence of ITPR1-reactive lymphocytes among peripheral blood mononuclear cells (PBMCs). Immunophenotypic profiling of PBMCs protein demonstrated predominant proliferation of B cells, CD4 T cells and CD8 memory T cells following stimulation with purified ITPR1 protein. Patient ITPR1-IgG bound both to peripheral nervous tissue and to lung tumour tissue. A nerve biopsy showed lymphocyte infiltration (including cytotoxic CD8 cells), oedema, marked axonal loss and myelin-positive macrophages, indicating florid inflammation. ITPR1-IgG serum titres declined following tumour removal, paralleled by clinical stabilization.

CONCLUSIONS

Our findings expand the spectrum of clinical syndromes associated with ITPR1-IgG and suggest that autoimmunity to ITPR1 may underlie peripheral nervous system diseases (including GBS) in some patients and may be of paraneoplastic origin in a subset of cases.

The role of anti-aquaporin 4 antibody in the conversion of acute brainstem syndrome to neuromyelitis optica

Background

Acute brainstem syndrome (ABS) may herald multiple sclerosis (MS), neuromyelitis optica (NMO), or occur as an isolated syndrome. The aquaporin 4 (AQP4)-specific serum autoantibody, NMO-IgG, is a biomarker for NMO. However, the role of anti-AQP4 antibody in the conversion of ABS to NMO is unclear.

Methods

Thirty-one patients with first-event ABS were divided into two groups according to the presence of anti-AQP4 antibodies, their clinical features and outcomes were retrospectively analyzed.

Results

Fourteen of 31 patients (45.16 %) were seropositive for NMO-IgG. The 71.43 % of anti-AQP4 (+) ABS patients converted to NMO, while only 11.76 % of anti-AQP4 (-) ABS patients progressed to NMO. Anti-AQP4 (+) ABS patients demonstrated a higher IgG index (0.68 ± 0.43 vs 0.42 ± 0.13, p < 0.01) and Kurtzke Expanded Disability Status Scale (4.64 ± 0.93 vs 2.56 ± 0.81, p < 0.01) than anti-AQP4 (-) ABS patients. Area postrema clinical brainstem symptoms occurred more frequently in anti-AQP4 (+) ABS patients than those in anti-AQP4 (-) ABS patients (71.43 % vs 17.65 %, p = 0.004). In examination of magnetic resonance imaging (MRI), the 78.57 % of anti-AQP4 (+) ABS patients had medulla-predominant involvements in the sagittal view and dorsal-predominant involvements in the axial view.

Conclusions

ABS represents an inaugural or limited form of NMO in a high proportion of anti-AQP4 (+) patients.

MOG-IgG in NMO and related disorders: a multicenter study of 50 patients. Part 2: Epidemiology, clinical presentation, radiological and laboratory features, treatment responses, and long-term outcome

BACKGROUND

A subset of patients with neuromyelitis optica spectrum disorders (NMOSD) has been shown to be seropositive for myelin oligodendrocyte glycoprotein antibodies (MOG-IgG).

OBJECTIVE

To describe the epidemiological, clinical, radiological, cerebrospinal fluid (CSF), and electrophysiological features of a large cohort of MOG-IgG-positive patients with optic neuritis (ON) and/or myelitis (n = 50) as well as attack and long-term treatment outcomes.

METHODS

Retrospective multicenter study.

RESULTS

The sex ratio was 1:2.8 (m:f). Median age at onset was 31 years (range 6-70). The disease followed a multiphasic course in 80 % (median time-to-first-relapse 5 months; annualized relapse rate 0.92) and resulted in significant disability in 40 % (mean follow-up 75 ± 46.5 months), with severe visual impairment or functional blindness (36 %) and markedly impaired ambulation due to paresis or ataxia (25 %) as the most common long-term sequelae. Functional blindess in one or both eyes was noted during at least one ON attack in around 70 %. Perioptic enhancement was present in several patients. Besides acute tetra-/paraparesis, dysesthesia and pain were common in acute myelitis (70 %). Longitudinally extensive spinal cord lesions were frequent, but short lesions occurred at least once in 44 %. Fourty-one percent had a history of simultaneous ON and myelitis. Clinical or radiological involvement of the brain, brainstem, or cerebellum was present in 50 %; extra-opticospinal symptoms included intractable nausea and vomiting and respiratory insufficiency (fatal in one). CSF pleocytosis (partly neutrophilic) was present in 70 %, oligoclonal bands in only 13 %, and blood-CSF-barrier dysfunction in 32 %. Intravenous methylprednisolone (IVMP) and long-term immunosuppression were often effective; however, treatment failure leading to rapid accumulation of disability was noted in many patients as well as flare-ups after steroid withdrawal. Full recovery was achieved by plasma exchange in some cases, including after IVMP failure. Breakthrough attacks under azathioprine were linked to the drug-specific latency period and a lack of cotreatment with oral steroids. Methotrexate was effective in 5/6 patients. Interferon-beta was associated with ongoing or increasing disease activity. Rituximab and ofatumumab were effective in some patients. However, treatment with rituximab was followed by early relapses in several cases; end-of-dose relapses occurred 9-12 months after the first infusion. Coexisting autoimmunity was rare (9 %). Wingerchuk's 2006 and 2015 criteria for NMO(SD) and Barkhof and McDonald criteria for multiple sclerosis (MS) were met by 28 %, 32 %, 15 %, 33 %, respectively; MS had been suspected in 36 %. Disease onset or relapses were preceded by infection, vaccination, or pregnancy/delivery in several cases.

CONCLUSION

Our findings from a predominantly Caucasian cohort strongly argue against the concept of MOG-IgG denoting a mild and usually monophasic variant of NMOSD. The predominantly relapsing and often severe disease course and the short median time to second attack support the use of prophylactic long-term treatments in patients with MOG-IgG-positive ON and/or myelitis.

MOG-IgG in NMO and related disorders: a multicenter study of 50 patients. Part 1: Frequency, syndrome specificity, influence of disease activity, long-term course, association with AQP4-IgG, and origin

Background

Antibodies to myelin oligodendrocyte glycoprotein (MOG-IgG) have been suggested to play a role in a subset of patients with neuromyelitis optica and related disorders.

Objective

To assess (i) the frequency of MOG-IgG in a large and predominantly Caucasian cohort of patients with optic neuritis (ON) and/or myelitis; (ii) the frequency of MOG-IgG among AQP4-IgG-positive patients and vice versa; (iii) the origin and frequency of MOG-IgG in the cerebrospinal fluid (CSF); (iv) the presence of MOG-IgG at disease onset; and (v) the influence of disease activity and treatment status on MOG-IgG titers.

Methods

614 serum samples from patients with ON and/or myelitis and from controls, including 92 follow-up samples from 55 subjects, and 18 CSF samples were tested for MOG-IgG using a live cell-based assay (CBA) employing full-length human MOG-transfected HEK293A cells.

Results

MOG-IgG was detected in 95 sera from 50 patients with ON and/or myelitis, including 22/54 (40.7 %) patients with a history of both ON and myelitis, 22/103 (21.4 %) with a history of ON but no myelitis and 6/45 (13.3 %) with a history of longitudinally extensive transverse myelitis but no ON, and in 1 control patient with encephalitis and a connective tissue disorder, all of whom were negative for AQP4-IgG. MOG-IgG was absent in 221 further controls, including 83 patients with AQP4-IgG-seropositive neuromyelitis optica spectrum disorders and 85 with multiple sclerosis (MS). MOG-IgG was found in 12/18 (67 %) CSF samples from MOG-IgG-seropositive patients; the MOG-IgG-specific antibody index was negative in all cases, indicating a predominantly peripheral origin of CSF MOG-IgG. Serum and CSF MOG-IgG belonged to the complement-activating IgG1 subclass. MOG-IgG was present already at disease onset. The antibodies remained detectable in 40/45 (89 %) follow-up samples obtained over a median period of 16.5 months (range 0–123). Serum titers were higher during attacks than during remission (p < 0.0001), highest during attacks of simultaneous myelitis and ON, lowest during acute isolated ON, and declined following treatment.

Conclusions

To date, this is the largest cohort studied for IgG to human full-length MOG by means of an up-to-date CBA. MOG-IgG is present in a substantial subset of patients with ON and/or myelitis, but not in classical MS. Co-existence of MOG-IgG and AQP4-IgG is highly uncommon. CSF MOG-IgG is of extrathecal origin. Serum MOG-IgG is present already at disease onset and remains detectable in the long-term course. Serum titers depend on disease activity and treatment status.

Vitamin D level status in Thai neuromyelitis optica patients

Vitamin D status of Thai clinically isolated syndrome (CIS), multiple sclerosis (MS) and NMO/neuromyelitis optica spectrum disorders (NMOSD) patients were prospectively collected (N=130). Its associations with disability score, and disease activity were sought. Mean vitamin D levels were not significantly different (CIS, 22.18±8.2; MS, 23.41±11.9; NMO/NMOSD, 23.54±9.3ng/mL; p=0.857). Prevalence of vitamin D insufficiency and deficiency (≤30ng/mL) was 73-80%. Neither disability score nor disease activity was associated with vitamin D level. Vitamin D insufficiency was common in Thai CIS, MS, and NMO/NMOSD patients without association with disability or disease activity.

Screening for MOG-IgG and 27 other anti-glial and anti-neuronal autoantibodies in 'pattern II multiple sclerosis' and brain biopsy findings in a MOG-IgG-positive case

BACKGROUND

Histopathological studies have revealed four different immunopathological patterns of lesion pathology in early multiple sclerosis (MS). Pattern II MS is characterised by immunoglobulin and complement deposition in addition to T-cell and macrophage infiltration and is more likely to respond to plasma exchange therapy, suggesting a contribution of autoantibodies.

OBJECTIVE

To assess the frequency of anti-myelin oligodendrocyte glycoprotein (MOG), anti-M1-aquaporin-4 (AQP4), anti-M23-AQP4, anti-N-methyl-d-aspartate-type glutamate receptors (NMDAR) and 25 other anti-neural antibodies in pattern II MS.

METHODS

Thirty-nine serum samples from patients with MS who had undergone brain biopsy (n = 24; including 13 from patients with pattern II MS) and from histopathologically non-classified MS patients (n = 15) were tested for anti-MOG, anti-M1-AQP4, anti-M23-AQP4, anti-NMDAR, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-type glutamate receptors (AMPAR), anti-gamma-aminobutyric acid receptors (GABA_BR), anti-leucine-rich, glioma-activated protein 1 (LGI1), anti-contactin-associated protein 2 (CASPR2), anti-dipeptidyl-peptidase-like protein-6 (DPPX), anti-Tr/Delta/notch-like epidermal growth factor-related receptor (DNER), anti-Hu, anti-Yo, anti-Ri, anti-Ma1/Ma2, anti-CV2/collapsin response mediator protein 5 (CRMP5), anti-glutamic acid decarboxylase (GAD), anti-amphiphysin, anti-Ca/RhoGTPase-activating protein 26 (ARHGAP26), anti-Sj/inositol-1,4,5-trisphosphate receptor 1 (ITPR1), anti-Homer3, anti-carbonic anhydrase-related protein (CARPVIII), anti-protein kinase gamma (PKCgamma), anti-glutamate receptor delta 2 (GluRdelta2), anti-metabotropic glutamate receptor 1 (mGluR1) and anti-mGluR5, as well as for anti-glial nuclei antibodies (AGNA) and Purkinje cell antibody 2 (PCA2).

RESULTS

Antibodies to MOG belonging to the complement-activating immunoglobulin G1 (IgG1) subclass were detected in a patient with pattern II MS. Detailed brain biopsy findings are shown.

CONCLUSION

This is the largest study on established anti-neural antibodies performed in MS so far. MOG-IgG may play a role in a small percentage of patients diagnosed with pattern II MS.

Devic's disease before Devic: Bilateral optic neuritis and simultaneous myelitis in a young woman (1874)

Neuromyelitis optica (NMO, Devic's disease) is an often severely disabling disorder of the central nervous system (CNS) which mainly affects the optic nerves and spinal cord. NMO was long considered a clinical subform of multiple sclerosis (MS). In 2004, however, Lennon and colleagues described a novel autoantibody in NMO which targets aquaporin-4, the most abundant water channel in the CNS, and which was later shown to be directly pathogenic. This has led to the recognition of NMO as a distinct disease entity in its own right. While the history of 'classical' MS has been extensively studied, only little is known about the early history of NMO. The term neuromyelitis optica was coined in 1894 by Eugène Devic (1858-1930) and Fernand Gault (1873-1936), who were the first to provide a systematic description of that disorder. Here we re-present a very early description of a case of NMO by a Polish physician, Adolf Wurst, which appeared in 1876 in Przegląd Lekarski, one of the oldest Polish medical journals. This report predates Devic and Gault's seminal work on NMO by more than two decades. The patient, a 30-year-old woman, subacutely developed simultaneous bilateral optic neuritis with papilloedema and bilateral blindness and transverse myelitis with severe paraparesis, anaesthesia, and bladder and bowel dysfunction. At last follow-up, one year after onset, she had recovered except for a residual spastic gait and some visual deficit on the right side. Of note, this is the first known case of NMO in a Caucasian patient ever reported outside Western Europe.

'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 3: Anti-Yo/CDR2, anti-Nb/AP3B2, PCA-2, anti-Tr/DNER, other antibodies, diagnostic pitfalls, summary and outlook

Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa head antibodies' due to their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects and provides a summary and outlook.

Central Nervous System Idiopathic Inflammatory Demyelinating Disorders in South Americans: A Descriptive, Multicenter, Cross-Sectional Study

The idiopathic inflammatory demyelinating disease (IIDD) spectrum has been investigated among different populations, and the results have indicated a low relative frequency of neuromyelitis optica (NMO) among multiple sclerosis (MS) cases in whites (1.2%-1.5%), increasing in Mestizos (8%) and Africans (15.4%-27.5%) living in areas of low MS prevalence. South America (SA) was colonized by Europeans from the Iberian Peninsula, and their miscegenation with natives and Africans slaves resulted in significant racial mixing. The current study analyzed the IIDD spectrum in SA after accounting for the ethnic heterogeneity of its population. A cross-sectional multicenter study was performed. Only individuals followed in 2011 with a confirmed diagnosis of IIDD using new diagnostic criteria were considered eligible. Patients’ demographic, clinical and laboratory data were collected. In all, 1,917 individuals from 22 MS centers were included (73.7% female, 63.0% white, 28.0% African, 7.0% Mestizo, and 0.2% Asian). The main disease categories and their associated frequencies were MS (76.9%), NMO (11.8%), other NMO syndromes (6.5%), CIS (3.5%), ADEM (1.0%), and acute encephalopathy (0.4%). Females predominated in all main categories. The white ethnicity also predominated, except in NMO. Except in ADEM, the disease onset occurred between 20 and 39 years old, early onset in 8.2% of all cases, and late onset occurred in 8.9%. The long-term morbidity after a mean disease time of 9.28±7.7 years was characterized by mild disability in all categories except in NMO, which was scored as moderate. Disease time among those with MS was positively correlated with the expanded disability status scale (EDSS) score (r=0.374; p=<0.001). This correlation was not observed in people with NMO or those with other NMO spectrum disorders (NMOSDs). Among patients with NMO, 83.2% showed a relapsing-remitting course, and 16.8% showed a monophasic course. The NMO-IgG antibody tested using indirect immunofluorescence (IIF) with a composite substrate of mouse tissues in 200 NMOSD cases was positive in people with NMO (95/162; 58.6%), longitudinally extensive transverse myelitis (10/30; 33.3%) and bilateral or recurrent optic neuritis (8/8; 100%). No association of NMO-IgG antibody positivity was found with gender, age at onset, ethnicity, early or late onset forms, disease course, or long-term severe disability. The relative frequency of NMO among relapsing-remitting MS (RRMS) + NMO cases in SA was 14.0%. Despite the high degree of miscegenation found in SA, MS affects three quarters of all patients with IIDD, mainly white young women who share similar clinical characteristics to those in Western populations in the northern hemisphere, with the exception of ethnicity; approximately one-third of all cases occur among non-white individuals. At the last assessment, the majority of RRMS patients showed mild disability, and the risk for secondary progression was significantly superior among those of African ethnicity. NMO comprises 11.8% of all IIDD cases in SA, affecting mostly young African-Brazilian women, evolving with a recurrent course and causing moderate or severe disability in both ethnic groups. The South-North gradient with increasing NMO and non-white individuals from Argentina, Paraguay, Brazil and Venezuela confirmed previous studies showing a higher frequency of NMO among non-white populations.

Update on biomarkers in neuromyelitis optica

Neuromyelitis optica (NMO) (and NMO spectrum disorder) is an autoimmune inflammatory disease of the CNS primarily affecting spinal cord and optic nerves. Reliable and sensitive biomarkers for onset, relapse, and progression in NMO are urgently needed because of the heterogeneous clinical presentation, severity of neurologic disability following relapses, and variability of therapeutic response. Detecting aquaporin-4 (AQP4) antibodies (AQP4-IgG or NMO-IgG) in serum supports the diagnosis of seropositive NMO. However, whether AQP4-IgG levels correlate with disease activity, severity, response to therapy, or long-term outcomes is unclear. Moreover, biomarkers for patients with seronegative NMO have yet to be defined and validated. Collaborative international studies hold great promise for establishing and validating biomarkers that are useful in therapeutic trials and clinical management. In this review, we discuss known and potential biomarkers for NMO.

Antibodies to the inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) in cerebellar ataxia

We report on a serum autoantibody associated with cerebellar ataxia. Immunohistochemical studies of sera from four patients referred for autoantibody testing revealed binding of high-titer (up to 1:5,000) IgG antibodies, mainly IgG1, to the molecular layer, Purkinje cell layer, and white matter on mouse, rat, porcine, and monkey cerebellum sections. The antibody bound to PC somata, dendrites, and axons, resulting in a binding pattern similar to that reported for anti-Ca/anti-ARHGAP26, but did not react with recombinant ARHGAP26. Extensive control studies were performed to rule out a broad panel of previously described paraneoplastic and non-paraneoplastic anti-neural autoantibodies. The characteristic binding pattern as well as double staining experiments suggested inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) as the target antigen. Verification of the antigen included specific neutralization of the tissue reaction following preadsorption with ITPR1 (but not ARHGAP26) and a dot-blot assay with purified ITPR1 protein. By contrast, anti-ARHGAP26-positive sera did not bind to ITPR1. In a parallel approach, a combination of histoimmunoprecipitation and mass spectrometry also identified ITPR1 as the target antigen. Finally, a recombinant cell-based immunofluorescence assay using HEK293 cells expressing ITPR1 and ARHGAP26, respectively, confirmed the identification of ITPR1. Mutations of ITPR1 have previously been implicated in spinocerebellar ataxia with and without cognitive decline. Our findings suggest a role of autoimmunity against ITPR1 in the pathogenesis of autoimmune cerebellitis and extend the panel of diagnostic markers for this disease.

Comparison between the cranial magnetic resonance imaging features of neuromyelitis optica spectrum disorder versus multiple sclerosis in Taiwanese patients

Background

Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) are inflammatory diseases of the central nervous system with different pathogenesis, brain lesion patterns, and treatment strategies. However, it is still difficult to distinguish these two disease entities by neuroimaging studies. Herein, we attempt to differentiate NMOSD from MS by comparing brain lesion patterns on magnetic resonance imaging (MRI).

Methods

The medical records and cranial MRI studies of patients with NMOSD diagnosed according to the 2006 Wingerchuk criteria and the presence of anti-aquaporin 4 (anti-AQP4) antibodies, and patients with MS diagnosed according to the Poser criteria, were retrospectively reviewed.

Results

Twenty-five NMOSD and 29 MS patients were recruited. The NMOSD patients became wheelchair dependent earlier than MS patients (log rank test; P = 0.036). Linear ependymal (28% vs. 0%, P = 0.003) and punctate lesions (64% vs. 28%, P = 0.013) were more frequently seen in NMOSD patients. Ten NMOSD patients (40%) had brain lesions that did not meet the Matthews criteria (MS were separated from NMOSD by the presence of at least 1 lesion adjacent to the body of the lateral ventricle and in the inferior temporal lobe; or the presence of a subcortical U-fiber lesion or a Dawson finger-type lesion). The different image patterns of NMOSD didn’t correlate with the clinical prognosis. However, NMOSD patients with more (≧10) brain lesions at onset became wheelchair dependence earlier than those with fewer (<10) brain lesions (log rank test; P < 0.001).

Conclusions

The diagnostic sensitivity of NMOSD criteria can be increased to 56% by combining the presence of linear ependymal lesions with unmet the Matthews criteria. The prognoses of NMOSD and MS are different. A specific imaging marker, the linear ependymal lesion, was present in some NMOSD patients. The diagnosis of NMOSD can be improved by following the evolution of this imaging feature when anti-AQP4 antibody test results are not available.

Biomarkers for neuromyelitis optica

Neuromyelitis optica (NMO) is an acquired, heterogeneous inflammatory disorder, which is characterized by recurrent optic neuritis and longitudinally extensive spinal cord lesions. The discovery of the serum autoantibody marker, anti-aquaporin 4 (anti-AQP4) antibody, revolutionizes our understanding of pathogenesis of NMO. In addition to anti-AQP4 antibody, other biomarkers for NMO are also reported. These candidate biomarkers are particularly involved in T helper (Th)17 and astrocytic damages, which play a critical role in the development of NMO lesions. Among them, IL-6 in the peripheral blood is associated with anti-AQP4 antibody production. Glial fibrillary acidic protein (GFAP) in CSF demonstrates good correlations with clinical severity of NMO relapses. Detecting these useful biomarkers may be useful in the diagnosis and evaluation of disease activity of NMO. Development of compounds targeting these biomarkers may provide novel therapeutic strategies for NMO. This article will review the related biomarker studies in NMO and discuss the potential therapeutics targeting these biomarkers.

Evaluation of aquaporin-4 antibody assays

Aquaporin-4 (AQP4) is a water channel protein that is most highly, but not exclusively, expressed in the central nervous system. In 2005 AQP4 was shown to be the antigenic target of neuromyelitis optica-immunoglobulin G (NMO-IgG, or AQP4-IgG), an antibody found specifically in patients with NMO and in formes frustes of NMO, such as longitudinally extensive transverse myelitis (LETM) or optic neuritis (ON). This discovery facilitated the clinical, pathological, and radiological distinction of NMO and the spectrum of NMO-related disorders from classical multiple sclerosis. In addition to its use as a diagnostic tool, AQP4-IgG predicts a high risk of relapse in patients with a clinically isolated syndrome of either LETM or ON. As disability in NMO is attack-related, early diagnosis and treatment are predicted to have a major effect on long-term disability. Thus, the importance of sensitive and specific assays to detect AQP4-IgG cannot be overstated. Both academic institutions and commercial companies have developed assays to identify AQP4-IgG in patients' sera or cerebrospinal fluid. Both AQP4 isoforms from different species have been used as the antigenic target in the form of frozen tissue sections in indirect immunofluorescence assays, partially purified protein for fluorescence immunoprecipitation assay, radioimmunoprecipita-tion assay or enzyme-linked immunosorbent assay, or transfected into cells for cell based assays or flow cytometry. We carried out a systematic review of the literature reporting different methodologies used to identify AQP4-IgG, examine whether longitudinal AQP4-IgG titers predict relapses in seropositive patients, and attempt to establish a reasonable timeframe for retesting negative serum samples.

CD19 as a molecular target in CNS autoimmunity

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are the most prevalent neuroinflammatory diseases of the central nervous system (CNS). The immunological cascade of these disorders is complex, and the exact spatial and temporal role of different immune cells is not fully understood. Although MS has been considered for many years to be primarily T cell driven, it is well established that B cells and the humoral immune response play an important role in its pathogenesis. This has long been evident from laboratory findings that include the presence of oligoclonal bands in the CSF. In NMO, the importance of the humoral immune system appears even more obvious as evidenced by pathogenic antibodies against aquaporin 4 (AQP4). Besides their capacity to mature into antibody-producing plasma cells, B cells are potent antigen-presenting cells to T lymphocytes and they can provide soluble factors for cell activation and differentiation to other immune-competent cells. In MS and NMO, there are substantial data from clinical trials that B cell depletion with CD20-directed agents is effective and relatively safe. Plasma cells, which produce antibodies against molecular targets expressed by the host, but which also provide humoral immune responses against pathogens, are not targeted by anti-CD20 therapies. Therefore, the depletion of CD19-expressing cells would offer potential advantages with regard to efficacy, but potentially higher risks with regard to infectious complications. This review will outline the rationale for CD19 as a molecular target in CNS autoimmunity. The current stage of drug development is illustrated. Potential safety concerns will be discussed.

Aquaporin-4 antibody testing: direct comparison of M1-AQP4-DNA-transfected cells with leaky scanning versus M23-AQP4-DNA-transfected cells as antigenic substrate

BACKGROUND

Neuromyelitis optica (NMO, Devic syndrome) is associated with antibodies to aquaporin-4 (NMO-IgG/AQP4-Ab) in the majority of cases. NMO-IgG/AQP4-Ab seropositivity in patients with NMO and its spectrum disorders has important differential diagnostic, prognostic and therapeutic implications. So-called cell-based assays (CBA) are thought to provide the best AQP4-Ab detection rates.

OBJECTIVE

To compare directly the AQP4-IgG detection rates of the currently most widely used commercial CBA, which employs cells transfected with a full-length (M1)-human AQP4 DNA in a fashion that allows leaky scanning (LS) and thus expression of M23-AQP4 in addition to M1-AQP, to that of a newly developed CBA from the same manufacturer employing cells transfected with human M23-AQP4-DNA.

METHODS

Results from 368 serum samples that had been referred for routine AQP4-IgG determination and had been tested in parallel in the two assays were compared.

RESULTS

Seventy-seven out of 368 samples (20.9%) were positive for NMO-IgG/AQP4-Ab in at least one assay. Of these, 73 (94.8%) were positive in both assays. A single sample (1.3%) was exclusively positive in the novel assay; three samples (3.9%) were unequivocally positive only in the 'classic' assay due to high background intensity in the novel assay. Both median fluorescence intensity and background intensity were higher in the new assay.

CONCLUSIONS

This large study did not reveal significant differences in AQP4-IgG detection rates between the 'classic' CBA and a new M23-DNA-based CBA. Importantly, our results largely re-affirm the validity of previous studies that had used the 'classic' AQP4-CBA to establish NMO-IgG/AQP4-Ab seropositivity rates in NMO and in a variety of NMO spectrum disorders.

An immunoassay that distinguishes real neuromyelitis optica signals from a labeling detected in patients receiving natalizumab

BACKGROUND

Cell-based assays for neuromyelitis optica (NMO) diagnosis are the most sensitive and specific methods to detect anti-aquaporin 4 (AQP4) antibodies in serum, but some improvements in their quantitative and specificity capacities would be desirable. Thus the aim of the present work was to develop a sensitive quantitative method for detection of anti-AQP4 antibodies that allows clear diagnosis of NMO and distinction of false labeling produced by natalizumab treatment.

METHODS

Sera from 167 individuals, patients diagnosed with NMO (16), multiple sclerosis (85), optic neuritis (24), idiopathic myelitis (21), or other neurological disorders (13) and healthy controls (8), were used as the primary antibody in an immunofluorescence assay on HEK cells transfected with the M23 isoform of human AQP4 fused with enhanced green fluorescent protein. Cells used were freshly transfected or stored frozen and then thawed just before adding the serum.

RESULTS

Microscopic observation and fluorescence quantification produced similar results in fresh and frozen samples. Serum samples from patients diagnosed with NMO were 100% positive for anti-AQP4 antibodies, while all the other sera were negative. Using serum from patients treated with natalizumab, a small and unspecific fluorescent signal was produced from all HEK cells, regardless of AQP4 expression.

CONCLUSIONS

Our cell-based double-label fluorescence immunoassay protocol significantly increases the signal specificity and reduces false diagnosis of NMO patients, especially in those receiving natalizumab treatment. Frozen pretreated cells allow faster detection of anti-AQP4 antibodies.

Neuromyelitis optica: clinical features, immunopathogenesis and treatment

The term 'neuromyelitis optica' ('Devic's syndrome', NMO) refers to a syndrome characterized by optic neuritis and myelitis. In recent years, the condition has raised enormous interest among scientists and clinical neurologists, fuelled by the detection of a specific serum immunoglobulin (Ig)G reactivity (NMO-IgG) in up to 80% of patients with NMO. These autoantibodies were later shown to target aquaporin-4 (AQP4), the most abundant water channel in the central nervous system (CNS). Here we give an up-to-date overview of the clinical and paraclinical features, immunopathogenesis and treatment of NMO. We discuss the widening clinical spectrum of AQP4-related autoimmunity, the role of magnetic resonance imaging (MRI) and new diagnostic means such as optical coherence tomography in the diagnosis of NMO, the role of NMO-IgG, T cells and granulocytes in the pathophysiology of NMO, and outline prospects for new and emerging therapies for this rare, but often devastating condition.

Aquaporin-4 antibodies (NMO-IgG) as a serological marker of neuromyelitis optica: a critical review of the literature

Antibodies to aquaporin-4 (called NMO-IgG or AQP4-Ab) constitute a sensitive and highly specific serum marker of neuromyelitis optica (NMO) that can facilitate the differential diagnosis of NMO and classic multiple sclerosis. NMO-IgG/AQP4-Ab seropositive status has also important prognostic and therapeutic implications in patients with isolated longitudinally extensive myelitis (LETM) or optic neuritis (ON). In this article, we comprehensively review and critically appraise the existing literature on NMO-IgG/AQP4-Ab testing. All available immunoassays-including tissue-based (IHC), cell-based (ICC, FACS) and protein-based (RIPA, FIPA, ELISA, Western blotting) assays-and their differential advantages and disadvantages are discussed. Estimates for sensitivity, specificity, and positive and negative likelihood ratios are calculated for all published studies and accuracies of the various immunoassay techniques compared. Subgroup analyses are provided for NMO, LETM and ON, for relapsing vs. monophasic disease, and for various control groups (eg, MS vs. other controls). Numerous aspects of NMO-IgG/AQP4-Ab testing relevant for clinicians (eg, impact of antibody titers and longitudinal testing, indications for repeat testing, relevance of CSF testing and subclass analysis, NMO-IgG/AQP4-Ab in patients with rheumatic diseases) as well as technical aspects (eg, AQP4-M1 vs. AQP4-M23-based assays, intact AQP4 vs. peptide substrates, effect of storage conditions and freeze/thaw cycles) and pitfalls are discussed. Finally, recommendations for the clinical application of NMO-IgG/AQP4-Ab serology are given.

The Presence of Autoantibodies Against Vascular and Nervous Tissue in Sera From Patients with Neuro-Behçet's Disease

INTRODUCTION

Behçet's disease is a chronic inflammatory disease of unknown aetiology that affects multiple organ systems. Since the diagnosis of this disease mainly relies on clinical criteria, a diagnostic laboratory test is required especially for neuro-Behçet's patients without systemic involvement.

METHOD

In this study, we searched for the presence of autoantibodies against brain tissue, by means of indirect immunofluorescent staining technique in sera obtained from patients with neuro-Behçet's disease, based on reports that humoral immune dysregulation may play a role in susceptibility to Behçet's disease. After pre-absorbtion of sera with guinea pig liver powder to reduce nonspecific staining, serum samples were applied to mouse brain sections and immunoreactivity was detected with fluorescein (FITC)-conjugated goat antibody against human IgG.

RESULTS

Ten sera from neuro-Behçet's patients and 10 age-matched control sera were screened for immunoreactivity. We detected specific immunoreactivity to both parenchymal and vascular brain structures in the patients' sera. Parenchymal vessel immunopositivity was detected in 8 of 10 patients, whereas only two of control sera showed no significant parenchymal vascular immunoreactivity (p=.025). In addition to vascular immunoreactivity, filamentous and reticular immunopositive structures were detected in brain sections of 5 out of 10 patients. No such immunoreactivity was detected in sections incubated with control sera (p=.016).

CONCLUSION

We detected a specific immunoreactivity against vascular and parenchymal filamentous structures in neuro-Behçet patients' sera. Humoral autoimmunity may play a role in the pathogenesis of neuro-Behçet's disease in addition to cellular immune response. Findings of this preliminary study will be evaluated with a large number of patients and controls, to determine whether it is the cause or the result and, further studies are underway to disclose the nature of epitope to which the immunoreactivity was directed against and to develop a diagnostic laboratory method for investigating central nervous system involvement in Behçet's patients.

Immunopathogenesis of neuromyelitis optica

Neuromyelitis optica (NMO, Devic's syndrome) is a clinical syndrome characterized by optic neuritis and (mostly longitudinally extensive) myelitis. If untreated, NMO usually takes a relapsing course and often results in blindness and tetra- or paraparesis. The discovery of autoantibodies to aquaporin-4, the most abundant water channel in the CNS, in 70-80% of patients with NMO (termed NMO-IgG or AQP4-Ab) and subsequent investigations into the pathogenic impact of this new reactivity have led to the recognition of NMO as an autoimmune condition and as a disease entity in its own right, distinct from classic multiple sclerosis. Here, we comprehensively review the current knowledge on the role of NMO-IgG/AQP4-Ab, B cells, T cells, and the innate immune system in the pathogenesis of NMO.

Evaluation of aquaporin-4 antibody assays

Aquaporin-4 (AQP4) is a water channel protein that is most highly, but not exclusively, expressed in the central nervous system. In 2005 AQP4 was shown to be the antigenic target of neuromyelitis optica-immunoglobulin G (NMO-IgG, or AQP4-IgG), an antibody found specifically in patients with NMO and in formes frustes of NMO, such as longitudinally extensive transverse myelitis (LETM) or optic neuritis (ON). This discovery facilitated the clinical, pathological, and radiological distinction of NMO and the spectrum of NMO-related disorders from classical multiple sclerosis. In addition to its use as a diagnostic tool, AQP4-IgG predicts a high risk of relapse in patients with a clinically isolated syndrome of either LETM or ON. As disability in NMO is attack-related, early diagnosis and treatment are predicted to have a major effect on long-term disability. Thus, the importance of sensitive and specific assays to detect AQP4-IgG cannot be overstated. Both academic institutions and commercial companies have developed assays to identify AQP4-IgG in patients' sera or cerebrospinal fluid. Both AQP4 isoforms from different species have been used as the antigenic target in the form of frozen tissue sections in indirect immunofluorescence assays, partially purified protein for fluorescence immunoprecipitation assay, radioimmunoprecipita-tion assay or enzyme-linked immunosorbent assay, or transfected into cells for cell based assays or flow cytometry. We carried out a systematic review of the literature reporting different methodologies used to identify AQP4-IgG, examine whether longitudinal AQP4-IgG titers predict relapses in seropositive patients, and attempt to establish a reasonable timeframe for retesting negative serum samples.

Clinical, paraclinical and serological findings in Susac syndrome: an international multicenter study

Background

Susac syndrome (SuS) is a rare disorder thought to be caused by autoimmune-mediated occlusions of microvessels in the brain, retina and inner ear leading to central nervous system (CNS) dysfunction, visual disturbances due to branch retinal artery occlusions (BRAO), and hearing deficits. Recently, a role for anti-endothelial cell antibodies (AECA) in SuS has been proposed.

Objectives

To report the clinical and paraclinical findings in the largest single series of patients so far and to investigate the frequency, titers, and clinical relevance of AECA in SuS.

Patients and methods

A total of 107 serum samples from 20 patients with definite SuS, 5 with abortive forms of SuS (all with BRAO), and 70 controls were tested for AECA by immunohistochemistry employing primate brain tissue sections.

Results

IgG-AECA >1:100 were detected in 25% (5/20) of patients with definite SuS and in 4.3% (3/70) of the controls. Median titers were significantly higher in SuS (1:3200, range 1:100 to 1:17500) than in controls (1:100, range 1:10 to 1:320); IgG-AECA titers >1:320 were exclusively present in patients with SuS; three controls had very low titers (1:10). Follow-up samples (n = 4) from a seropositive SuS patient obtained over a period of 29 months remained positive at high titers. In all seropositive cases, AECA belonged to the complement-activating IgG1 subclass. All but one of the IgG-AECA-positive samples were positive also for IgA-AECA and 45% for IgM-AECA. SuS took a severe and relapsing course in most patients and was associated with bilateral visual and hearing impairment, a broad panel of neurological and neuropsychological symptoms, and brain atrophy in the majority of cases. Seropositive and seronegative patients did not differ with regard to any of the clinical or paraclinical parameters analyzed.

Conclusions

SuS took a severe and protracted course in the present cohort, resulting in significant impairment. Our finding of high-titer IgG1 and IgM AECA in some patients suggest that humoral autoimmunity targeting the microvasculature may play a role in the pathogenesis of SuS, at least in a subset of patients. Further studies are warranted to define the exact target structures of AECA in SuS.

Update on the diagnosis and treatment of neuromyelitis optica: recommendations of the Neuromyelitis Optica Study Group (NEMOS)

Neuromyelitis optica (NMO, Devic’s syndrome), long considered a clinical variant of multiple sclerosis, is now regarded as a distinct disease entity. Major progress has been made in the diagnosis and treatment of NMO since aquaporin-4 antibodies (AQP4-Ab; also termed NMO-IgG) were first described in 2004. In this review, the Neuromyelitis Optica Study Group (NEMOS) summarizes recently obtained knowledge on NMO and highlights new developments in its diagnosis and treatment, based on current guidelines, the published literature and expert discussion at regular NEMOS meetings. Testing of AQP4-Ab is essential and is the most important test in the diagnostic work-up of suspected NMO, and helps to distinguish NMO from other autoimmune diseases. Furthermore, AQP4-Ab testing has expanded our knowledge of the clinical presentation of NMO spectrum disorders (NMOSD). In addition, imaging techniques, particularly magnetic resonance imaging of the brain and spinal cord, are obligatory in the diagnostic workup. It is important to note that brain lesions in NMO and NMOSD are not uncommon, do not rule out the diagnosis, and show characteristic patterns. Other imaging modalities such as optical coherence tomography are proposed as useful tools in the assessment of retinal damage. Therapy of NMO should be initiated early. Azathioprine and rituximab are suggested as first-line treatments, the latter being increasingly regarded as an established therapy with long-term efficacy and an acceptable safety profile in NMO patients. Other immunosuppressive drugs, such as methotrexate, mycophenolate mofetil and mitoxantrone, are recommended as second-line treatments. Promising new therapies are emerging in the form of anti-IL6 receptor, anti-complement or anti-AQP4-Ab biologicals.

Aquaporin-4 antibodies, CNS acidosis and neuromyelitis optica: a potential link

BACKGROUND

Neuromyelitis optica (NMO, Devic's syndrome) is a severely disabling disorder of the central nervous system characterized by optic neuritis and longitudinally extensive myelitis. In around 80% of cases, NMO is caused by autoantibodies to astrocytic aquaporin-4 (AQP4), the most abundant water channel in the CNS. Acute NMO attacks are frequently accompanied by elevated levels of lactate in the cerebrospinal fluid (CSF). As a strongly dissociated anion (pK'=3.7) directly changing the strong ion difference, lactate causes a reduction in the dependent anion [HCO3-] and a rise in [H+], resulting in "metabolic" acidosis in the CSF. CSF acidosis also develops during respiratory failure due to brainstem or high cervical spinal cord lesions, the most common cause of death in NMO. However, lactic acid and more generally, a decrease in pH, has been shown to increase the membrane expression of AQP4 in astrocytes. An increase in AQP4 membrane expression during acute NMO attacks could potentially enhance the complement-mediated humoral immune reaction against AQP4-expressing astrocytes characteristic for NMO and, thus, result in more severe astrocytic damage. Moreover, lactate and acidosis have been shown to cause astrocytic swelling and to affect astrocytic viability, potentially rendering astrocytes more susceptible to AQP4-Ab-mediated damage. Finally, increased AQP4 expression could be an independent risk factor in NMO and other forms of CNS inflammation, as indicated by the finding of grossly attenuated experimental autoimmune encephalomyelitis in AQP4-null mice. Therefore, we hypothesize that CSF acidosis might play a role in the pathophysiology of AQP4-Ab-positive NMO and that alterations in CSF pH might possibly influence the outcome of acute attacks in this condition. In addition, we discuss potential clinical implications and make proposals on how to test the hypothesis. Finally, other factors that influence astrocytic AQP4 membrane expression and might play a role in NMO are discussed.