NMO-IgG predicts the outcome of recurrent optic neuritis

Utility of aquaporin-4 antibody assay in patients with neuromyelitis optica spectrum disorders

OBJECTIVE

Our aim was to evaluate the utility of aquaporin-4 antibodies (AQP4-Ab) in patients with neuromyelitis optica spectrum disorders (NMOSD).

METHODS

The clinical and radiological characteristics of 78 patients with NMOSD and 22 with multiple sclerosis (MS), who were tested for AQP4-Ab by a cell-based assay, were assessed.

RESULTS

The mean time interval between symptom onset and development of optic neuritis and myelitis was 39.9 months in neuromyelitis optica (NMO). About 40% of patients with limited NMO would have fulfilled the diagnostic criteria for MS in the absence of the antibody assay results. In patients with longitudinally extensive transverse myelitis, positive AQP4-Ab assay results were associated with the poor response to acute steroid treatment and asymptomatic visual evoked potential abnormality. Presence of either painful tonic spasm associated with myelitis or severe disability at onset had high specificity and relatively high sensitivity in differentiating NMOSD with AQP4-Ab from MS.

CONCLUSIONS

The AQP4-Ab assay can facilitate the early diagnosis of NMO and prevent limited NMO from being misdiagnosed as MS. It can predict the poor response to first-line acute-phase treatment and probably detect the subclinical optic nerve involvement in subgroups of NMOSD. Lastly, it will contribute to the upcoming revision of the current diagnostic criteria for NMO.

The history of neuromyelitis optica

The discovery of a novel serum autoantibody (termed NMO-IgG or AQP4-Ab) in a subset of patients in 2004 has revived interest in neuromyelitis optica (NMO). While the history of classical multiple sclerosis has been extensively studied, only little is known about the history of NMO. In the present article, we provide a comprehensive review of the early history of this rare but intriguing syndrome. We trace the origins of the concept of NMO in the 19th century medical literature and follow its evolution throughout the 20th and into the 21st century. Finally, we discuss recent proposals to revise the concept of NMO and explain why there is indeed a need for a more systematic and descriptive nomenclature.

Clinical efficacy of plasmapheresis in patients with neuromyelitis optica spectrum disorder and effects on circulating anti-aquaporin-4 antibody levels

Background and Purpose

Although plasmapheresis is becoming standard practice as a rescue therapy for neuromyelitis optica (NMO), evidence for the therapeutic efficacy of plasmapheresis is limited, and the effect of plasmapheresis on anti-aquaporin-4 (AQP4) levels in patients with NMO has not been reported. Here, our objective was to evaluate the clinical efficacy of therapeutic plasmapheresis and its effect on anti-AQP4 antibody levels in patients with NMO spectrum disorder (NMOSD).

Methods

We retrospectively reviewed the medical records of 15 patients with NMOSD who had 18 acute attacks and received plasmapheresis because they did not respond to high-dose intravenous methylprednisolone (IVMP) therapy. Anti-AQP4 antibodies were measured before and after plasmapheresis. The primary outcomes were functional improvements immediately and 6 months after plasmapheresis, and the secondary outcome was the change in anti-AQP4 antibody serum levels following plasmapheresis.

Results

Plasmapheresis following IVMP therapy led to significant improvement in 50% of the 18 attacks in 15 patients immediately after the procedure was completed, and in 78% (14 attacks) after 6 months. Plasmapheresis was generally well tolerated in all patients. Anti-AQP4 antibody serum levels declined significantly following plasmapheresis, to a mean of 15% of the preplasmapheresis levels. Lower scores on the visual outcome scale recorded before an attack were associated with significant immediate improvement upon the completion of plasmapheresis (p=0.03).

Conclusions

Plasmapheresis following IVMP therapy effectively removed anti-AQP4 antibodies and was accompanied by a substantial improvement in the neurological disability of patients with NMOSD. Lower levels of pre-existing neurological damage may be associated with an improved acute response to plasmapheresis.

Helicobacter pylori infection in Neuromyelitis Optica and Multiple Sclerosis

OBJECTIVE

To determine the Helicobacter pylori infection status in patients with multiple sclerosis (MS) and neuromyelitis optica (NMO) spectrum.

METHODS

H. pylori infection was certified by indirect immunofluorescence assay. Aquaporin-4 (AQP4) antibody was detected by cell-based assay. H. pylori seroprevalence was measured in 118 patients with NMO (n = 52), high-risk NMO (hrNMO, longitudinally extensive transverse myelitis, n = 17 and recurrent optic neuritis, n = 7), MS (n = 42) and healthy controls (n = 27). Logistic regression analysis was used to determine associations between H. pylori infection and NMO and MS.

RESULTS

H. pylori antibodies were present in 119 serum samples (82.1%, 119/145), with antibody positivity in 90.4% (47/52) of the patients with NMO, 95.8% (23/24) of the patients with hrNMO, 73.8% (31/42) of the patients with MS and 59.3% (16/27) of the controls. NMO spectrum patients had greater positivity for H. pylori than MS patients (p < 0.05) and controls (p < 0.05). The frequency of H. pylori seropositivity did not significantly differ between MS patients and controls (p = 0.726). H. pylori seropositivity was significantly higher in AQP4 antibody-positive patients (54/58, 93.1%; p = 0.038) than in AQP4 antibody-negative patients (48/60, 80%). Logistic regression analysis showed that H. pylori seropositivity was significantly associated with hrNMO [odds ratio (OR) = 9.311, p = 0.005] or hrNMO + NMO (OR = 6.350, p = 0.028).

CONCLUSION

H. pylori infection was present in most Chinese patients with NMO and hrNMO, and may be a risk factor for the NMO spectrum.

Persisting myelin oligodendrocyte glycoprotein antibodies in aquaporin-4 antibody negative pediatric neuromyelitis optica

BACKGROUND

Recently we showed that antibodies to myelin oligodendrocyte glycoprotein (MOG) can be found in aquaporin-4 (AQP4)-immunoglobulin (IgG) seronegative pediatric and adult patients with definite and high-risk neuromyelitis optica (NMO).

OBJECTIVE

The purpose of this study was to describe the clinical characteristics and temporal dynamics of MOG-IgG in AQP4-IgG seronegative pediatric patients presenting with definite NMO.

METHODS

Children with definite NMO who were referred for further testing of serum antibodies for AQP4 and MOG with a cell-based assay were included in this study. Clinical disease course, cerebrospinal fluid and magnetic resonance imaging (MRI) studies of these patients were reviewed.

RESULTS

Between 2008 and 2012 eight children who fulfilled the diagnostic criteria of definite NMO were recruited. Two children with definite NMO tested positive for AQP4-IgG but were negative for MOG-IgG antibodies. Three children had an absence of AQP4-IgG and MOG-IgG antibodies. Three children with definite NMO had high titers of serum MOG-IgG antibodies (≥1: 160), but no AQP4-directed humoral immune response. Longitudinal analysis of serum samples of the latter three children showed persisting high MOG-IgG titers over time.

CONCLUSION

Pediatric patients presenting with clinical symptoms and MRI findings highly suggestive of NMO but with high and persisting MOG-IgG antibody titers are most likely to represent a distinct subgroup of acute demyelinating diseases with important clinical and therapeutic implications.

Relationship between NMO-antibody and anti-MOG antibody in optic neuritis

BACKGROUND

Damage to astrocytes by anti-aquaporin-4 antibody (AQP4-Ab), also known as NMO antibody, has been implicated as the cause of neuromyelitis optica. Myelin oligodendrocyte glycoprotein (MOG) is well known as the causative protein of multiple sclerosis (MS). MOG antigen is currently considered as a cause of optic neuritis (ON) associated with MS because immunization with MOG antigen derived from oligodendrocytes induces murine ON with myelitis. We investigated the relationship between NMO antibody (NMO-Ab) and anti-MOG antibody (MOG-Ab) and potential in patients with ON for recovery of vision.

METHODS

Thirty-three eyes of 23 patients with ON were studied. At presentation, serum NMO-Ab was measured by immunofluorescence using HEK 293 cells transfected with AQP4-GFP, and anti-MOG1-125 antibody was measured by enzyme-linked immunosorbent assay. MOG-Ab seropositivity was defined by comparing with MOG-Ab level obtained from 8 healthy normal subjects.

RESULTS

Eleven (47%) of 23 ON patients were NMO-Ab seropositive, while 8 (34%) of the 23 patients were MOG-Ab seropositive. Six (26%) of 23 patients were seropositive for both NMO-Ab and MOG-Ab. Ten (43%) of 23 patients were seronegative for both antibodies. Three (50%) of 6 eyes of patients seropositive for both antibodies did not respond to corticosteroid pulse therapy and plasmapheresis, and visual acuity remained unchanged. In the NMO-Ab/MOG-Ab group, visual acuity improved significantly (P < 0.0001). In the other 3 groups (NMO-Ab/MOG-Ab, NMO-Ab/MOG-Ab, and NMO-Ab/MOG-Ab), visual acuity did not change significantly (P = 0.53, 0.42, and 0.45, respectively).

CONCLUSION

NMO-Ab and MOG-Ab could be potential biomarkers to determine visual prognosis in patients with ON.

Neuromyelitis optica

Neuromyelitis optica (NMO) is a disabling inflammatory condition that targets astrocytes in the optic nerves and spinal cord. Neuro-ophthalmologists must be particularly aware of this disorder because about half of patients present as isolated unilateral optic neuritis months or years before a disease-defining and often crippling bout of myelitis. NMO is easily confused with multiple sclerosis because it is characterized by relapses that lead to stepwise accrual of deficits. The best predictor of conversion from optic neuritis to clinical definite NMO is the presence of a serum antibody to aquaporin-4 called NMO-IgG. However, this test is currently only about 75% sensitive. Suspicion of NMO should be high in patients who present with vision of light perception or worse or who are left with acuity of 20/50 or worse after optic neuritis and in those with simultaneous bilateral optic neuritis or recurrent attacks. Acute NMO relapses are generally treated with high-dose intravenous steroids, with plasma exchange often used as a rescue therapy for those who do not respond. Preventative strategies against relapses currently use broad-spectrum or selective B-lymphocyte immune suppression, but their use is based on small, generally uncontrolled studies. Hopefully, the future will bring more sensitive tools for defining risk and predicting outcome, as well as more targeted and effective forms of therapy.

The neuro-ophthalmology of multiple sclerosis

Multiple sclerosis (MS) is a disease marked by focal demyelinating inflammatory plaques throughout the CNS. Neuro-ophthalmologic sequelae are common in MS and may arise from the disease itself or from treatment of the disease. Both afferent and efferent functions may be affected. Despite much progress, our understanding of the pathophysiology of MS, and the efficacy of our available treatments, remain inadequate. Here, we review the chief neuro-ophthalmologic abnormalities associated with MS and discuss the emerging diagnostic and therapeutic advances that are likely to further our understanding of MS and its treatment.

Neuromyelitis optica spectrum disorders

Neuromyelitis optica is an uncommon inflammatory demyelinating CNS disorder that is distinct from multiple sclerosis with respect to clinical, laboratory, neuroimaging, and prognostic characteristics. Autoantibodies that target aquaporin-4 are highly specific for neuromyelitis optica and have helped define a spectrum of disease beyond the classic definition of acute transverse myelitis and optic neuritis. Accumulating evidence supports the pathogenic potential that these autoantibodies possess in relation to the unique vasculocentric immunopathology of the disease. Current treatment strategies therefore include the use of corticosteroids and plasmapheresis for acute attacks and general or humoral immunosuppression for attack prevention. Ongoing research will focus on establishing the pathogenic mechanisms of the disease, in part derived from newly reported animal models, and testing-focused treatment strategies that evolve from this knowledge.

Treatment of pediatric optic neuritis

OPINION STATEMENT

Pediatric optic neuritis is a rare disorder causing a subacute loss of vision (often bilateral) in children, often of a severe degree. Common clinical findings include dense visual field loss, afferent pupillary defect (APD) in unilateral cases, and papillitis that is often bilateral. Contrary to optic neuritis in the adult population, the differential diagnosis for this disorder in pediatric patients is quite extensive, so neuroimaging and serologic evaluation are necessary to exclude an infectious or neoplastic process. Pediatric optic neuritis may occur as a clinically isolated syndrome, or in association with diffuse neurologic dysfunction, such as acute disseminated encephalomyelitis (ADEM). Optic neuritis may also be the first episode heralding the onset of pediatric multiple sclerosis or neuromyelitis optica (NMO or Devic's disease). Therefore, formal neurologic evaluation and follow-up are indicated. Although the management of this disorder in adults is well described, there is a paucity of evidence-based, prospective clinical data on its management and treatment in a pediatric population. The current treatment of pediatric optic neuritis consists of 3 to 5 days of intravenous methylprednisolone (4-30 mg/kg per day), followed by a prolonged oral corticosteroid taper. A prolonged course of oral steroid (2-4 weeks) is recommended to avoid recurrence, which is common in this age group. Some controversy persists concerning the exposure of children to high-dose parenteral corticosteroids to treat an entity that is usually self-limited, but given the severity of vision loss in one or both eyes in this population, this intervention is standard in neuro-ophthalmologic practice.

Identifying autoantigens in demyelinating diseases: valuable clues to diagnosis and treatment?

PURPOSE OF REVIEW

Identification of autoantigens in demyelinating diseases is essential for the understanding of the pathogenesis. Immune responses against these antigens could be used as biomarkers for diagnosis, prognosis and treatment responses. Knowledge of antigen-specific immune responses in individual patients is also a prerequisite for antigen-based therapies.

RECENT FINDINGS

A proportion of patients with demyelinating disease have antibodies to aquaporin 4 (AQP4) or myelin oligodendrocyte glycoprotein (MOG). Patients with anti-AQP4 have the distinct clinical presentation of neuromyelitis optica (NMO), and these patients often also harbour other autoimmune responses. In contrast, anti-MOG is seen in patients with different disease entities such as childhood multiple sclerosis (MS), acute demyelinating encephalomyelitis (ADEM), anti-AQP4 negative NMO, and optic neuritis, but hardly in adult MS. A number of new candidate autoantigens have been identified and await validation. Antigen-based therapies are mainly aimed at tolerizing T-cell responses against myelin basic protein (MBP) and have shown only modest or no clinical benefit so far.

SUMMARY

Currently, only few patients with demyelinating diseases can be characterized based on their autoantibody profile. The most prominent antigens in this respect are MOG and AQP4. Further research has to focus on the validation of newly discovered antigens as biomarkers.

Idiopathic transverse myelitis and neuromyelitis optica: clinical profiles, pathophysiology and therapeutic choices

Transverse myelitis is a focal inflammatory disorder of the spinal cord which may arise due to different etiologies. Transverse myelitis may be idiopathic or related/secondary to other diseases including infections, connective tissue disorders and other autoimmune diseases. It may be also associated with optic neuritis (neuromyelitis optica), which may precede transverse myelitis. In this manuscript we review the pathophysiology of different types of transverse myelitis and neuromyelitis optica and discuss diagnostic criteria for idiopathic transverse myelitis and risk of development of multiple sclerosis after an episode of transverse myelitis. We also discuss treatment options including corticosteroids, immunosuppressives and monoclonal antibodies, plasma exchange and intravenous immunoglobulins.

Aquaporin-4 antibodies are not related to HTLV-1 associated myelopathy

Introduction

The seroprevalence of human T-cell leukemia virus type 1 (HTLV-1) is very high among Brazilians (∼1∶200). HTLV-1 associated myelopathy or tropical spastic paraparesis (HAM/TSP) is the most common neurological complication of HTLV-1 infection. HAM/TSP can present with an acute/subacute form of longitudinally extensive myelitis, which can be confused with lesions seen in aquaporin-4 antibody (AQP4-Ab) positive neuromyelitis optica spectrum disorders (NMOSD) on MRI. Moreover, clinical attacks in patients with NMOSD have been shown to be preceded by viral infections in around 30% of cases.

Objective

To evaluate the frequency of AQP4-Ab in patients with HAM/TSP. To evaluate the frequency of HTLV-1 infection in patients with NMOSD.

Patients and Methods

23 Brazilian patients with HAM/TSP, 20 asymptomatic HTLV-1+ serostatus patients, and 34 with NMOSD were tested for AQP4-Ab using a standardized recombinant cell based assay. In addition, all patients were tested for HTLV-1 by ELISA and Western blotting.

Results

20/34 NMOSD patients were positive for AQP4-Ab but none of the HAM/TSP patients and none of the asymptomatic HTLV-1 infected individuals. Conversely, all AQP4-Ab-positive NMOSD patients were negative for HTLV-1 antibodies. One patient with HAM/TSP developed optic neuritis in addition to subacute LETM; this patient was AQP4-Ab negative as well. Patients were found to be predominantly female and of African descent both in the NMOSD and in the HAM/TSP group; Osame scale and expanded disability status scale scores did not differ significantly between the two groups.

Conclusions

Our results argue both against a role of antibodies to AQP4 in the pathogenesis of HAM/TSP and against an association between HTLV-1 infection and the development of AQP4-Ab. Moreover, the absence of HTLV-1 in all patients with NMOSD suggests that HTLV-1 is not a common trigger of acute attacks in patients with AQP4-Ab positive NMOSD in populations with high HTLV-1 seroprevalence.

Testing for antibodies to human aquaporin-4 by ELISA: sensitivity, specificity, and direct comparison with immunohistochemistry

BACKGROUND

Several assays have been developed to detect antibodies to aquaporin-4 (NMO-IgG/AQP4-Ab). However, many of these assays require sophisticated techniques and are thus only available at specialized laboratories. This is problematic since NMO-IgG/AQP4-Ab testing has important prognostic and therapeutic implications.

OBJECTIVE

To evaluate a newly developed, commercial, enzyme-linked immunosorbent assay (ELISA) for detecting NMO-IgG/AQP4-Ab.

METHODS

Serum samples from 261 patients with NMO spectrum disorders (NMOSD; n=108) and controls (n=153) were tested for AQP4-Ab by using ELISA. Of these patients, 207 were tested in parallel using a standard immunohistochemical (IHC) assay.

RESULTS

Fifty of 66 (75.8%) patients with NMO, 17/25 (68%) with LETM, 3/14 (21.4%) with ON, 2/3 (66.7%) with ON and non-extensive transverse myelitis, and 2/153 (1.3%) controls tested positive in the ELISA. Of those NMOSD patients tested by both ELISA and IHC, 10 were positive only in the ELISA and 3 exclusively in the IHC assay, suggesting that the overall sensitivity of the ELISA was higher than that of the standard IHC assay. The ELISA yielded very good intra- and inter-run reproducibility with regard to AQP4-Ab detection and good intrarun, but only moderate inter-run reproducibility with regard to AQP4-Ab quantification. Anti-AQP4 serum concentrations correlated with disease activity (p<0.00001), but did not differ between patients with NMO and patients with isolated LETM or ON.

CONCLUSION

The ELISA evaluated here provides a relatively sensitive and easy-to-use diagnostic tool for detecting antibodies to AQP4 and could make AQP4-Ab testing, which is of high clinical relevance, more widely available.

Evaluation of a multiparametric immunofluorescence assay for standardization of neuromyelitis optica serology

BACKGROUND

Neuromyelitis optica (NMO) is a severely disabling autoimmune disorder of the central nervous system, which predominantly affects the optic nerves and spinal cord. In a majority of cases, NMO is associated with antibodies to aquaporin-4 (AQP4) (termed NMO-IgG).

AIMS

In this study, we evaluated a new multiparametric indirect immunofluorescence (IIF) assay for NMO serology.

METHODS

Sera from 20 patients with NMO, 41 patients with multiple sclerosis (MS), 30 healthy subjects, and a commercial anti-AQP4 IgG antibody were tested in a commercial composite immunofluorescence assay ("Neurology Mosaic 17"; Euroimmun, Germany), consisting of five different diagnostic substrates (HEK cells transfected with AQP4, non-transfected HEK cells, primate cerebellum, cerebrum, and optic nerve tissue sections).

RESULTS

We identified AQP4 specific and non-specific fluorescence staining patterns and established positivity criteria. Based on these criteria, this kit yielded a high sensitivity (95%) and specificity (100%) for NMO and had a significant positive and negative likelihood ratio (LR+ = ∞, LR- = 0.05). Moreover, a 100% inter- and intra-laboratory reproducibility was found.

CONCLUSIONS

The biochip mosaic assay tested in this study is a powerful tool for NMO serology, fast to perform, highly sensitive and specific for NMO, reproducible, and suitable for inter-laboratory standardization as required for multi-centre clinical trials.

Update on neuromyelitis optica: natural history and management

Neuromyelitis optica or Devic disease is an inflammatory disorder of the central nervous system. It is caused by antibodies that attack aquaporin 4 water channels in the cell membrane of astrocytic foot processes at the blood brain barrier. It can involve the optic nerve, the spinal cord and beyond. Here we review its pathophysiology, clinical features, and therapy.

From bench to MS bedside: challenges translating biomarker discovery to clinical practice

A substantial need exists for developing and validating a range of biomarkers that would address a number of important unmet clinical needs in the MS field. In spite of considerable efforts over last years, very few putative biomarkers have been fully validated or successfully integrated into routine clinical practice. Here, we consider some of the main challenges that have limited such effective translation from biomarker discovery to the bedside in the context of MS, the prototypic chronic human CNS inflammatory illness. We will define the types of biomarkers that would be relevant for MS, identify their ideal attributes, and then discuss individual challenges and strategies to overcome them.

Neuromyelitis optica: an antibody-mediated disorder of the central nervous system

Neuromyelitis optica (NMO) is a recurrent inflammatory disease that preferentially targets the optic nerves and spinal cord leading to blindness and paralysis. The hallmarks of NMO include bilateral optic neuritis and longitudinally extensive transverse myelitis. Woman and African Americans are overrepresented in the US patient population. NMO is associated with the NMO-IgG biomarker, which targets the aquaporin-4 water channel on astrocytes. The humoral pathology of NMO lesions include IgG and IgM deposits and infiltration by granulocytes suggesting that the NMO-IgG may be involved in the pathogenesis of disease. This review of the recent NMO literature covers the clinical features, epidemiology, radiology and pathology of disease and includes discussion of the important basic science research work in the field.

Contrasting disease patterns in seropositive and seronegative neuromyelitis optica: A multicentre study of 175 patients

Background

The diagnostic and pathophysiological relevance of antibodies to aquaporin-4 (AQP4-Ab) in patients with neuromyelitis optica spectrum disorders (NMOSD) has been intensively studied. However, little is known so far about the clinical impact of AQP4-Ab seropositivity.

Objective

To analyse systematically the clinical and paraclinical features associated with NMO spectrum disorders in Caucasians in a stratified fashion according to the patients' AQP4-Ab serostatus.

Methods

Retrospective study of 175 Caucasian patients (AQP4-Ab positive in 78.3%).

Results

Seropositive patients were found to be predominantly female (p < 0.0003), to more often have signs of co-existing autoimmunity (p < 0.00001), and to experience more severe clinical attacks. A visual acuity of ≤ 0.1 during acute optic neuritis (ON) attacks was more frequent among seropositives (p < 0.002). Similarly, motor symptoms were more common in seropositive patients, the median Medical Research Council scale (MRC) grade worse, and MRC grades ≤ 2 more frequent, in particular if patients met the 2006 revised criteria (p < 0.005, p < 0.006 and p < 0.01, respectively), the total spinal cord lesion load was higher (p < 0.006), and lesions ≥ 6 vertebral segments as well as entire spinal cord involvement more frequent (p < 0.003 and p < 0.043). By contrast, bilateral ON at onset was more common in seronegatives (p < 0.007), as was simultaneous ON and myelitis (p < 0.001); accordingly, the time to diagnosis of NMO was shorter in the seronegative group (p < 0.029). The course of disease was more often monophasic in seronegatives (p < 0.008). Seropositives and seronegatives did not differ significantly with regard to age at onset, time to relapse, annualized relapse rates, outcome from relapse (complete, partial, no recovery), annualized EDSS increase, mortality rate, supratentorial brain lesions, brainstem lesions, history of carcinoma, frequency of preceding infections, oligoclonal bands, or CSF pleocytosis. Both the time to relapse and the time to diagnosis was longer if the disease started with ON (p < 0.002 and p < 0.013). Motor symptoms or tetraparesis at first myelitis and > 1 myelitis attacks in the first year were identified as possible predictors of a worse outcome.

Conclusion

This study provides an overview of the clinical and paraclinical features of NMOSD in Caucasians and demonstrates a number of distinct disease characteristics in seropositive and seronegative patients.

Aquaporin 4 antibodies in the cerebrospinal fluid are helpful in diagnosing Chinese patients with neuromyelitis optica

OBJECTIVE

It was the aim of this study to compare the diagnostic efficiency of anti-aquaporin 4 (AQP4) antibody detection between serum and cerebrospinal fluid (CSF) samples in Chinese patients with central nervous system demyelinating diseases.

METHODS

Anti-AQP4 antibodies were detected by a cell-based assay. We calculated the sensitivity, specificity and coherence in 118 patients with neuromyelitis optica (NMO, n = 39), multiple sclerosis (n = 34), longitudinally extensive transverse myelitis (LETM, n = 22), optic neuritis (ON, n = 6), opticospinal multiple sclerosis (n = 8) and acute partial transverse myelitis (n = 9).

RESULTS

Forty-four serum samples (33.8%) were positive for anti-AQP4 antibodies. Anti-AQP4 antibody seropositivity was 76.9, 59.1 and 16.7% in patients with NMO, LETM and ON, respectively. Sixty-five CSF samples (50%) were positive for anti-AQP4 antibodies. Anti-AQP4 antibody positivity was 87.1, 81.8, 83.3, 62.5 and 11.8% in patients with NMO, LETM, ON, opticospinal multiple sclerosis and multiple sclerosis, respectively. The κ value of the coherence test was 0.585 (p < 0.0001) between the two types of samples. The antibody positivity rate was significantly different between the two body fluids (p = 0.0008, McNemar test). The sensitivity and specificity were 74.3 and 100% in serum, 85.7 and 88.2% in CSF, and 94.3 and 88.2% for serum and CSF combined, respectively.

CONCLUSION

The sensitivity of anti-AQP4 antibodies in the CSF was higher than that in the serum, and their combined use is helpful in diagnosing Chinese patients with NMO.

Complement activating antibodies to myelin oligodendrocyte glycoprotein in neuromyelitis optica and related disorders

Background

Serum autoantibodies against the water channel aquaporin-4 (AQP4) are important diagnostic biomarkers and pathogenic factors for neuromyelitis optica (NMO). However, AQP4-IgG are absent in 5-40% of all NMO patients and the target of the autoimmune response in these patients is unknown. Since recent studies indicate that autoimmune responses to myelin oligodendrocyte glycoprotein (MOG) can induce an NMO-like disease in experimental animal models, we speculate that MOG might be an autoantigen in AQP4-IgG seronegative NMO. Although high-titer autoantibodies to human native MOG were mainly detected in a subgroup of pediatric acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) patients, their role in NMO and High-risk NMO (HR-NMO; recurrent optic neuritis-rON or longitudinally extensive transverse myelitis-LETM) remains unresolved.

Results

We analyzed patients with definite NMO (n = 45), HR-NMO (n = 53), ADEM (n = 33), clinically isolated syndromes presenting with myelitis or optic neuritis (CIS, n = 32), MS (n = 71) and controls (n = 101; 24 other neurological diseases-OND, 27 systemic lupus erythematosus-SLE and 50 healthy subjects) for serum IgG to MOG and AQP4. Furthermore, we investigated whether these antibodies can mediate complement dependent cytotoxicity (CDC). AQP4-IgG was found in patients with NMO (n = 43, 96%), HR-NMO (n = 32, 60%) and in one CIS patient (3%), but was absent in ADEM, MS and controls. High-titer MOG-IgG was found in patients with ADEM (n = 14, 42%), NMO (n = 3, 7%), HR-NMO (n = 7, 13%, 5 rON and 2 LETM), CIS (n = 2, 6%), MS (n = 2, 3%) and controls (n = 3, 3%, two SLE and one OND). Two of the three MOG-IgG positive NMO patients and all seven MOG-IgG positive HR-NMO patients were negative for AQP4-IgG. Thus, MOG-IgG were found in both AQP4-IgG seronegative NMO patients and seven of 21 (33%) AQP4-IgG negative HR-NMO patients. Antibodies to MOG and AQP4 were predominantly of the IgG1 subtype, and were able to mediate CDC at high-titer levels.

Conclusions

We could show for the first time that a subset of AQP4-IgG seronegative patients with NMO and HR-NMO exhibit a MOG-IgG mediated immune response, whereas MOG is not a target antigen in cases with an AQP4-directed humoral immune response.

Neuromyelitis optica antibodies in patients with severe optic neuritis in China

BACKGROUND

Severe visual loss is seen in both multiple sclerosis-associated optic neuritis (ON) and neuromyelitis optica (NMO)-associated ON. NMO (aquaporin 4) antibodies have been reported to have diagnostic and prognostic value for visual and neurological outcomes of recurrent ON. We performed this study to investigate the frequency of NMO antibodies and its prognostic value for visual and neurological outcomes in Chinese patients with severe ON.

METHODS

Single-center prospective cohort study. Detection of NMO antibodies was by indirect immunofluorescence method using human aquaporin 4-transfected cells. Severe ON was defined as visual acuity of 20/200 or worse in at least 1 eye at the nadir of the patients' course. Clinical features at baseline, visual outcome, and sequential neurological events were compared between seropositive and seronegative groups.

RESULTS

NMO antibodies were detected in 11 of 34 patients (32.4%) with severe ON. Five seropositive patients with recurrent ON had significantly higher titers (range: 1:512 to 1:65,536; median: 1:512) than those of 6 seropositive patients with only 1 episode (range: 1:16 to 1:512; median: 1:32) (P=0.021). Female to male ratio (10:1) and antinuclear autoantibody positivity in seropositive patients (3 of 9, 33.3%) were statistically higher than those of the seronegative group (12:11; 0 of 19; P=0.026). The seropositive patients had significantly poorer visual outcomes than seronegative patients (P=0.025). During the averaged 32-month follow-up, 2 of 11 seropositive patients (18.2%) developed clinically incomplete transverse myelitis, while no similar symptoms were reported in the seronegative group.

CONCLUSION

NMO antibody positivity is relatively high in Chinese patients with severe ON and suggests a poorer visual outcome, probably higher risk of developing spinal cord lesions and a closer association with systemic autoimmune disorders.

Longitudinal extensive transverse myelitis--it's not all neuromyelitis optica

Longitudinal extensive transverse myelitis (LETM) is defined as a spinal cord lesion that extends over three or more vertebrae, as seen on MRI of the spine. The clinical presentation of a patient with LETM is often dramatic and can consist of paraparesis or tetraparesis, sensory disturbances, and gait, bladder, bowel and/or sexual dysfunction. LETM is a characteristic feature of neuromyelitis optica, but such spinal lesions can also occur in various other autoimmune and inflammatory diseases that involve the CNS--such as multiple sclerosis, sarcoidosis or Sjögren syndrome--or in infectious diseases with CNS involvement. Patients with a neoplastic disorder or traumatic spinal cord injury can also present with longitudinal spinal lesions. In this Review, the signs and symptoms that suggest various etiologies and differential diagnoses of LETM are described, and illustrated by educational case studies. The best therapeutic options for patients with each diagnosis are also discussed.

Acute disseminated encephalomyelitis and its place amongst other acute inflammatory demyelinating CNS disorders

The diagnosis of acute inflammatory demyelinating CNS conditions is complex and this is reflected in variations in how cohorts are defined across studies. For some conditions the diagnosis relies on whether it is monophasic or relapsing, in others the anatomical site of inflammation is used as a means of categorisation. Clinical features such as precipitants, gender and age may affect the probability of certain diagnoses, but are not highly accurate. Exclusive features for the pathology are identifiable for some but not all conditions, and are seldom available during life. Specific markers such as antibodies are informative and new developments in this area are likely in the near future. This review outlines the features and classification of acute disseminated encephalomyelitis and contrasts it with other related conditions before attempting to define a pragmatic organisation of these conditions based upon present evidence.

Quantitative measurement of anti-aquaporin-4 antibodies by enzyme-linked immunosorbent assay using purified recombinant human aquaporin-4

BACKGROUND

Antibodies to aquaporin-4 (AQP4-Ab), known as NMO-IgG, are a sensitive and specific marker for neuromyelitis optica (NMO).

METHODS

To develop an enzyme-linked immunosorbent assay (ELISA) for AQP4-Ab, we expressed M23 isoform of human AQP4 in a baculovirus system, and used it as an antigen. We measured AQP4-Ab in the sera of 300 individuals: 64 with definite NMO, 31 with high-risk NMO, 105 with multiple sclerosis (MS), 57 with other neurological diseases (ONDs), and 43 healthy controls. We also performed longitudinal measurements of AQP4-Ab in 787 samples collected from 51 patients with definite or high-risk NMO.

RESULTS

AQP4-Abs were positive in 72% with definite NMO, 55% with high-risk NMO, and 4% with MS, but none of the OND patients and the healthy individuals. The longitudinal measurement showed AQP4-Ab levels correlating with disease activity. Out of 38 initially seropositive patients, 21 became seronegative under effective immunosuppressive therapy. During most relapses, the serum AQP4-Ab levels were either high or rising compared with the previous value, although rising AQP4-Ab levels did not always lead to acute exacerbation. Two of the 13 initially seronegative patients converted to seropositive following acute exacerbations.

CONCLUSIONS

We established an AQP4-Ab ELISA, which could be a potential monitoring tool of disease activity.

New insights into neuromyelitis optica

Neuromyelitis optica (NMO) is an idiopathic inflammatory disorder of the central nervous system (CNS) that preferentially affects the optic nerves and spinal cord. In Asia, NMO has long been considered a subtype of multiple sclerosis (MS). However, recent clinical, pathological, immunological, and imaging studies have suggested that NMO is distinct from MS. This reconsideration of NMO was initially prompted by the discovery of a specific antibody for NMO (NMO-IgG) in 2004. NMO-IgG is an autoantibody that targets aquaporin-4 (AQP4), the most abundant water channel in the CNS; hence, it was named anti-AQP4 antibody. Since it demonstrated reasonable sensitivity and high specificity, anti-AQP4 antibody was incorporated into new diagnostic criteria for NMO.The spectrum of NMO is now known to be wider than was previously recognized and includes a proportion of patients with recurrent, isolated, longitudinally extensive myelitis or optic neuritis, and longitudinally extensive myelitis or optic neuritis associated with systemic autoimmune disease or with brain lesions typical of NMO. In this context, a new concept of "NMO spectrum disorders" was recently introduced. Furthermore, seropositivity for NMO-IgG predicts future relapses and is recognized as a prognostic marker for NMO spectrum disorders. Humoral immune mechanisms, including the activation of B-cells and the complement pathway, are considered to play important roles in NMO pathogenesis. This notion is supported by recent studies showing the potential pathogenic role of NMO-IgG as an initiator of NMO lesions. However, a demonstration of the involvement of NMO-IgG by the development of active immunization and passive transfer in animal models is still needed. This review focuses on the new concepts of NMO based on its pathophysiology and clinical characteristics. Potential management strategies for NMO in light of its pathomechanism are also discussed.

Cerebrospinal fluid B-cell expansion in longitudinally extensive transverse myelitis associated with neuromyelitis optica immunoglobulin G

A first episode of central nervous system (CNS) demyelination may represent heterogeneous entities such as acute disseminated encephalomyelitis, clinically isolated syndrome, neuromyelitis optica (NMO), or multiple sclerosis. As new immune therapies become available, it is increasingly important to make an early diagnosis. Autoantibodies such as NMO immunoglobulin G (IgG) and myelin oligodendrocyte glycoprotein IgG are increasingly being employed to define subgroups of CNS demyelination or guide treatment. Similarly, cerebrospinal fluid (CSF) immunophenotyping can demonstrate B-lymphocyte subpopulation expansion, which has been used to guide therapy in other autoimmune CNS disorders. We present a report on a 15-year-old male with longitudinally extensive transverse myelitis with magnetic resonance imaging findings of oedema, cavitation, and gadolinium enhancement. NMO-IgG and aquaporin 4 IgG were positive; thus, we diagnosed a limited form of NMO. Acute CSF immunophenotyping revealed a 3.6% expansion of CD19 B-cell populations, whereas a comparison group of five children (4 males, age range 2-15y; mean age 7y) with other neurological disorders showed only a 0.51% expansion (SD 0.25%). In view of the diagnosis of a 'limited form of neuromyelitis optica', we therefore elected to treat him aggressively from the outset with a prolonged steroid regimen and mycophenylate mofetil. This case demonstrates a correlation between autoantibody production and CSF B lymphocyte expansion in an individual with CNS demyelination. These approaches could be used in individuals with a first episode of CNS demyelination to help delineate immunological subgroups and guide treatment.

The use of serum glial fibrillary acidic protein measurements in the diagnosis of neuromyelitis optica spectrum optic neuritis

Background

Glial fibrillary acidic protein (GFAP) is a specific intermediate filament of the cytoskeleton of the astrocyte and may be used as a specific marker for astrocytic damage. It is detectable in the cerebrospinal fluid following a relapse caused by Multiple Sclerosis (MS) and Neuromyelitis Optica (NMO) spectrum disease. Higher levels are found following an NMO-related relapse. It is not known if GFAP is also detectable in the serum following such relapses. In particular, it is not known if lesions limited to the optic nerve release GFAP in sufficient quantities to be detectable within the serum. The aim of this study was to ascertain the extent to which serum GFAP levels can distinguish between an episode of optic neuritis (ON) related to NMO spectrum disease and ON from other causes.

Methodology/Principal Findings

Out of 150 patients consecutively presenting to our eye hospital over the period March 2009 until July 2010, we were able to collect a serum sample from 12 patients who had presented with MS-related ON and from 10 patients who had presented with NMO spectrum disease-related ON. We also identified 8 patients with recurrent isolated ON and 8 patients with a corticosteroid-dependent optic neuropathy in the absence of any identified aetiology. GFAP was detectable in the serum of all but three patients (two patients with MS-related ON and one with recurrent optic neuritis). The median serum GFAP level in the patient group with NMO spectrum disease was 4.63 pg/mL whereas in all other cases combined together, this was 2.14 pg/mL. The difference was statistically significant (P = 0.01). A similar statistically significant difference was found when cases with pathology limited to the optic nerve were compared (P = 0.03).

Conclusions

Glial pathology in NMO related optic neuritis is reflected in elevated serum GFAP levels independently of whether or not there is extra-optic nerve disease.

Clinical approach to optic neuritis: pitfalls, red flags and differential diagnosis

Demyelinating optic neuritis (ON) is the most common cause of optic neuropathy typically presenting with a subacute painful visual loss. In 20% of patients with multiple sclerosis (MS), ON is the presenting symptom and half of the patients with isolated ON develop MS within 15 years. The diagnosis of ON plays an important role in neurological practice. A correct and early diagnosis is necessary to ensure optimal further investigations and treatment. Other causes of optic neuropathies such as connective tissue disorders, infectious diseases, tumours or ischaemic neuropathies are less frequent but clinical and therapeutic management can differ dramatically. We present five patients admitted to our hospital with suspected demyelinating ON, but the clinical work up revealed different causes of optic neuropathy. We discuss the differential diagnosis of ON and clinical red flags that require careful diagnostic assessment of other diseases. A workflow for the diagnosis of optic neuropathies is presented.

Identifying patient subtypes in multiple sclerosis and tailoring immunotherapy: challenges for the future

The accelerating pace of technological and analytical development in the fields of genetic and phenotypic profiling has ushered in an era of great promise for multiple sclerosis (MS) research. As we continue to identify modest but meaningful associations to MS susceptibility, disease course, treatment response, and other clinical or paraclinical phenotypes, we must begin to (1) embark on the challenging set of studies that will integrate disparate observations into clinical algorithms, and (2) validate their clinical utility. Genetic data are receiving muchofthe attention today, but they are unlikelytobesufficienttooffer a personalized approach to disease management in MS. Rather, the genetic architecture of the disease, once uncovered, will offer a fixed platform upon which more dynamic molecular profiles can be assembled to deconstruct the structure of the patient population that we label with a diagnosis of MS. The tools and methods to gain insight into the heterogeneity of MS patients are available today; we must now realize their potential in enhancing the care of MS patients.

Neuromyelitis optica (NMO)--an autoimmune disease of the central nervous system (CNS)

In the past 10 years, neuromyelitis optica (NMO) has evolved from Devic's categorical clinical description into a broader disease spectrum. Serum IgG antibodies have been identified in NMO patients with the water channel aquaporin-4 (AQP4) as their main target antigen. AQP4 antibodies/NMO-IgG have been shown to be a highly specific and moderately sensitive serum biomarker for NMO. The immunopathology of NMO lesions supports that anti-AQP4 antibodies/NMO-IgG are involved in the pathogenesis of NMO. In vitro studies have demonstrated that human NMO-IgG induce necrosis and impair glutamate transport in astrocytes. Certain ethnic groups, notably of Asian and African origin, seem to be more susceptible to NMO than others. The genetic background for these putative differences is not known, a weak human leucocyte antigen association has been identified. AQP4 gene variants could represent a genetic susceptibility factor for different clinical phenotypes within the NMO spectrum. Experimental models have been described including a double-transgenic myelin-specific B- and T-cell mouse. NMO-like disease has been induced with passive transfer of human anti-AQP4 antibodies to the plasma of mice with pre-established experimental autoimmune encephalomyelitis or by intrathecal administration to naive mice. NMO may be characterized as a channelopathy of the central nervous system with autoimmune characteristics.

Diagnosis of neuromyelitis optica (NMO) spectrum disorders: is MRI obsolete?

INTRODUCTION

Neuromyelitis optica (NMO) is a severe demyelinating disease that preferentially involves spinal cord and optic nerve. It is part of a spectrum of neurological conditions associated with antibodies to aquaporin-4 (AQP4). This study investigates the role of MRI where novel, more sensitive AQP4 antibody immunoassay techniques are being used.

METHODS

Retrospective review of neuroimaging in 69 patients (25 antibody positive, 44 antibody negative), investigated in the context of suspected NMO or NMO spectrum disorder, was performed independently by two consultant neuroradiologists.

RESULTS

Longitudinally extensive, central spinal cord lesions were more frequent in AQP4 positive patients (95.2% vs 35.5%, p < 0.0001; 85.7% vs 45.2%, p = 0.015). Multiple sclerosis diagnostic criteria were less frequently fulfilled on brain MRI in antibody positive patients (5.6% vs 33.3%, p = 0.035). Juxtacortical and corpus callosal lesions were also less common in this group (16.7% vs 46.7%, p = 0.063; 5.6% vs 46.7%, p = 0.0034). Hypothalamic and periependymal disease related to the aqueduct was not seen in antibody negative patients. T1 hypointensity was more common in cord lesions of antibody positive patients (75.0% vs 35.3%, p = 0.037). However, this characteristic did not discriminate antibody positive and negative longitudinally extensive cord lesions (73.3% vs 62.5%, p = 0.66).

CONCLUSION

The NMO spectrum of diseases are among an increasing number of neurological conditions defined by serological tests. However, despite improved immunoassay techniques, MRI of the brain and spinal cord continues to be among the first-line investigations in these patients, providing valuable diagnostic information that will help guide patient management.

Frequency and syndrome specificity of antibodies to aquaporin-4 in neurological patients with rheumatic disorders

Background: A new autoantibody (termed NMO-IgG, or AQP4-Ab) has recently been described in patients with neuromyelitis optica (NMO) and its formes frustes, longitudinally extensive transverse myelitis (LETM) and recurrent optic neuritis (rON). However, AQP4-Ab has been found also in patients with co-existing rheumatic diseases such as systemic lupus erythematosus (SLE) or Sjögren’s syndrome (SS), conditions which are characterized by broad, polyspecific B cell activation.

Objectives: In this study, we aimed at evaluating the syndrome specificity and frequency of AQP4-Ab in patients with rheumatic diseases and neurological symptoms.

Methods: For this purpose, serum samples from 109 neurological patients with established connective tissue disorders (CTD) ( n = 54), possible CTD ( n = 42), or vasculitis ( n = 13) were analysed for the presence of AQP4-Ab by a cell-based assay employing recombinant human AQP4.

Results: AQP4-Ab was detectable in 31/40 (78%) patients with CTD and NMO spectrum disorders (median titre, 1:1000) but in none of the samples obtained from patients with CTD or vasculitis and neurological disorders other than NMO, LETM, or rON ( n = 69).

Conclusion: The high syndrome specificity of the antibody for neuromyelitis optica spectrum disorders (NMOSDs) in patients with CTD supports the concept of AQP4-Ab being involved in the pathogenesis of these neurological conditions, and argues against AQP4-Ab simply being part of the polyclonal B cell activation generally associated with rheumatic diseases. Moreover, the finding that AQP4-Ab is present in patients with CTD and co-existing NMOSD with approximately the same frequency as in patients without CTD strengthens the case of CTD and AQP4-Ab positive NMOSD representing two co-existing yet distinct entities in the majority of patients.

Neuromyelitis optica-IgG+ optic neuritis associated with celiac disease and dysgammaglobulinemia: a role for tacrolimus?

We present a pediatric case of recurrent optic neuritis, celiac disease, partial IgA and IgG3 deficiency in the context of anti-aquaporin-4 auto-immunity and familial IgA deficiency with celiac disease. Treatment with tacrolimus was successful in preventing disease relapses. This case stresses the relevance of central nervous system anti-aquaporin-4 auto-immunity in a broader context of immune dysregulation and neuro-immunology.

Clinical characteristics, therapeutic outcomes of isolated atypical optic neuritis in China

BACKGROUND/AIM

The causes of atypical optic neuritis are different from typical demyelinating optic neuritis. It may exist as an isolated entity or may be part of a systemic process. Our aim was to determine the clinical characteristics, and therapeutic outcomes of isolated atypical optic neuritis in China.

METHODS

Inclusion criteria for isolated atypical optic neuritis required fulfillment of at least one of (1)-(3) and both (4), and (5): (1) Visual loss progressing for >2 weeks since onset, (2) No visual recovery over 3 weeks after onset, (3) Worsening of vision over one line of acuity after withdrawal of corticosteroids, (4) No diagnosis of a defined collagen vascular disease or neurological autoimmune disease at onset, and (5) Neuro-ophthalmic follow-up for at least 12 months.

RESULTS

20 cases fulfilled isolated atypical optic neuritis inclusion criteria. 10 cases (50%) were anti-aquaporin-4 antibody positive. 11 of 20 cases (55%) with flare of optic neuritis at the withdrawal of corticosteroids responded poorly to reinitiation of corticosteroid therapy. At the end of follow-up (median 41 month), vision in 60% of involved eyes (18/30 eyes) was still 20/200 or worse.

CONCLUSIONS

In China, isolated atypical optic neuritis has a high incidence of anti-aquaporin-4 antibody and is resistant to corticosteroid therapy.