Seropositive Neuromyelitis Optica Research Articles

Sera from patients with seropositive neuromyelitis optica spectral disorders caused the degeneration of rodent optic nerve

Neuromyelitis optica (NMO) is an autoimmune inflammatory, neurodestructive disease primarily targeting the optic nerve and spinal cord. An autoantibody against water channel protein aquaporin-4 (AQP4), which is expressed at endofeet of astrocytes has been implicated in the pathogenesis of NMO. We evaluated the impact of sera of seropositive patients with NMO spectrum disorders (NMOSDs) on the rodent optic nerve and retina. Serum was obtained either from patients with seropositive NMOSD (AQP4+), seronegative patient with idiopathic optic neuritis (AQP4−), and healthy volunteers (control). Anti-AQP4 antibody in a serum was measured by a previously established cell-based assay. The patients' sera were applied on the optic nerve after de-sheathed. Immunohistochemistry showed that at 7 days after the treatment, the area of the optic nerve exposed to the AQP4+ sera lost expression of both AQP4 and glial fibrillary acidic protein. Also, Human-IgG immunoreactivity and marked invasion of inflammation cells were observed in the optic nerve treated with AQP4+ serum. Immnoreactivity of neurofilament was reduced at 14 days after the treatment, not 7 days. Real-time polymerase chain reaction revealed the reduced gene expression of neurofilament in retina from the eye that was exposed to the AQP4+ sera at 14 days. Retrograde fluorogold-labeling on the retinal flatmount disclosed the significantly reduced number of retinal ganglion cells when the AQP4+ sera were applied. The present model has demonstrated that the sera from patients with seropositive NMOSDs led to the regional astrocytic degeneration and inflammatory cell invasion in the optic nerve, resulting in the ultimate loss of RGCs and their axons at areas beyond the injury site.

The usefulness of brain MRI at onset in the differentiation of multiple sclerosis and seropositive neuromyelitis optica spectrum disorders

Background: Although neuromyelitis optica (NMO) is a central nervous system (CNS) autoimmune disease distinct from multiple sclerosis (MS). NMO and NMO spectrum disorder (NMOSD) sometimes show asymptomatic lesions on brain magnetic resonance imaging (MRI) at onset, and even present with symptomatic brain involvement. Objectives: We investigated whether brain MRI at onset can be helpful for the differentiation of MS and NMOSD. Methods: We retrospectively analyzed initial brain MRIs, performed within three months of onset, in patients with MS (n = 51) and anti-aquaporin4-antibody-positive patients with NMOSD (n = 67). Results: NMOSD patients met the Paty (37%) and Barkhof (13%) criteria, and the criteria of the European Magnetic Imaging in MS (MAGNIMS) study group (9%), for MS. Ovoid lesions perpendicular to the lateral ventricle, isolated juxtacortical lesions in U-fibers and isolated ovoid/round cortical lesions were found only in MS patients, whereas longitudinal corticospinal tract lesions, extensive hemispheric lesions, periependymal lesions surrounding the lateral ventricle and cervicomedullary lesions were found only in NMOSD patients. Conclusions: Our study suggests that it is difficult to differentiate MS from NMOSD by the fulfillment of the MRI criteria for MS on brain MRI at onset; however, the characteristic morphology of brain lesions is highly useful for the early differentiation of the two disorders.

A Chinese Lady with Combine Neuromyelitis Optica and Sjögren's Syndrome: A Case Report

Neuromyelitis optica (NMO) is an inflammatory demyelinating disorder of the central nervous system while Sjogren’s syn drome is a chronic systemic inflammatory disease. Co-existing NMO and Sjogren’s syndrome was reported as a rare asso ciation in the literature. We report a case of a middle-age Chinese woman presented with unilateral optic neuritis who was subsequently diagnosed with seropositive NMO and Sjogren’s syndrome with seropositivity for NMO-IgG and anti-Ro (SSA) antibodies respectively. Work up for other autoimmune disorders was negative. She was prescribed with oral azathioprine daily with no further attack of optic neuritis and longitudinal myelitis for 3 years. In view of high risk of relapse and signifi cant morbidity in most cases with NMO, rapid diagnosis and early initiation of aggressive immunosuppressive treatment are essential to minimize unfavorable outcomes.

Seropositive Neuromyelitis Optica: A Pediatric Case Report and 6-Year Follow-Up

Neuromyelitis optica is an autoimmune demyelinating disorder of the central nervous system. Although it has some features in common with multiple sclerosis, it has different clinical features, prognosis, and treatment. We describe a boy with seropositive neuromyelitis optica and his 6-year follow-up. A boy aged 5 years 8 months presented with relapsing optic neuritis, short segment transverse myelitis, and brain involvement. He met the diagnostic criteria for multiple sclerosis fulfilling the McDonald 2010 criteria; however, neuromyelitis optica immunoglobulin-G was detected, and the patient was diagnosed with neuromyelitis optica. He had frequent relapses until immunosuppressive treatment with azathioprine and low-dose prednisone was started. After he was asymptomatic for 2.5 years, prednisone was withdrawn, but he had a new attack soon after withdrawal of the steroid. It is important to differentiate neuromyelitis optica from multiple sclerosis because early immunosuppressive treatment prevents further disability, and longer periods of immunosuppressive treatment should be planned to prevent relapses.

Aquaporin-4 antibody–negative neuromyelitis optica

To optimize aquaporin-4 (AQP4) antibody (Ab) detection and to assess the influence of the increased sensitivity of the assay on the demographic and disease-related characteristics of a group of AQP4-Ab-negative patients. Serum samples were obtained from patients included in the French NOMADMUS database with a definite diagnosis of neuromyelitis optica (NMO) (n = 87) and were compared with controls (n = 54). They were tested by indirect immunofluorescence and cell-based assays (CBAs) in various conditions and with several plasmids. We identified the CBA on live cells transfected with the untagged AQP4-M23 isoform as the best method, with a sensitivity of 74.4% and a specificity of 100%. We demonstrated a direct relationship between improvement of the sensitivity of the detection method and the distinctiveness and characteristics of the AQP4-Ab-negative NMO group. Whereas with the classic indirect immunofluorescence or current AQP4-M1 CBA we found only slight differences between the 2 populations, using the AQP4-M23 CBA, we demonstrated that patients with AQP4-Ab-negative NMO expressed specific demographic and disease-related features. They were characterized by an equal male/female ratio (p < 0.001), a Caucasian ethnicity (p = 0.029), and an overrepresentation of simultaneous optic neuritis and transverse myelitis at first episode (p = 0.015). In terms of disability, they experienced a better visual acuity at last follow-up compared with seropositive NMO (p = 0.007). This raises the question of a distinct physiopathology for patients with AQP4-Ab-negative NMO and of their place in the spectrum of the disease.

Seronegative NMO

Aquaporin-4 (AQP4) antibody, or neuromyelitis optica (NMO)–immunoglobulin G (IgG), is an important diagnostic biomarker of definite and limited forms of NMO, collectively referred to as NMO spectrum disorders (NMOSD),1 but its detection in this syndrome is only 50% to 90%. AQP4 antibody–seronegative NMO poses a diagnostic challenge in clinical practice and represents a source of uncertainty in NMO clinical research.2 Assay sensitivity and patient selection may contribute to clinical uncertainty, but it is unresolved whether there are unique features of AQP4 antibody–negative NMO that are distinct from seropositive NMO. The authors thank Prof. Brian G. Weinshenker, Department of Neurology, Mayo Clinic, Rochester, MN, for suggestions.

Disease Amelioration With Tocilizumab in a Treatment-Resistant Patient With Neuromyelitis Optica

Neuromyelitis optica (NMO) is an autoimmune disease of the central nervous system in which aberrant antibody responses to the astrocytic water channel aquaporin 4 have been described. Experimental evidence is emerging that NMO is partly driven by the proinflammatory cytokine interleukin 6 (IL-6), which propagates the survival of disease-specific B cell subclasses, and deviates CD4+ T helper cell differentiation toward IL-17-producing T helper 17 cells. Tocilizumab is a recombinant humanized monoclonal antibody against the IL-6 receptor approved for treatment of rheumatoid arthritis. To study clinical and paraclinical effects of tocilizumab in a patient with NMO. Case report. Academic neurology department. A patient with highly active aquaporin 4–seropositive NMO who failed numerous immunosuppressive interventions, including high-dose corticosteroids, mitoxantrone, plasma exchange (PE), rituximab (anti-CD20), and alemtuzumab (anti-CD52), before receiving tocilizumab. Clinical disability, magnetic resonance imaging, cytokines and transcription factors levels in the cerebrospinal fluid, and peripheral blood mononuclear cells. A patient who continued to accumulate neurological disability and magnetic resonance imaging activity while receiving numerous immunoactive therapies stabilized, and eventually improved clinically and on magnetic resonance metrics after treatment initiation with tocilizumab. Treatment and clinical response correlated with a significant reduction of IL-6 levels in the CSF as well as a diminished expression of signal transducer and activator of transcription 3. Tocilizumab might be effective in NMO, here in a patient not responding to leukocyte depletion. Our findings further support data that implicate IL-6 as a critical molecule in the immunopathogenesis of NMO, and a critical role for T cells in the pathogenesis of this disorder.

Early presentation of neuromyelitis optica

Neuromyelitis optica is a rare autoimmune demyelinating disease of the central nervous system in childhood. Its relapsing form is usually reported in adults. We report a 3-year-old girl with relapsing, IgG seropositive neuromyelitis optica. Initially she presented with optic neuritis, followed by three relapses with deterioration of optic neuritis and developing transverse myelitis. With each relapse, the treatment was less effective. Four years after the onset of the disease, the patient was blind, had paraplegia associated with urinary and bowel incontinence and short stature.

Neuromyelitis optica IgG does not alter aquaporin‐4 water permeability, plasma membrane M1/M23 isoform content, or supramolecular assembly

Neuromyelitis optica (NMO) is thought to be caused by immunoglobulin G autoantibodies (NMO-IgG) against astrocyte water channel aquaporin-4 (AQP4). A recent study (Hinson et al. (2012) Proc Natl Acad Sci USA 109:1245-1250) reported that NMO-IgG inhibits AQP4 water permeability directly and causes rapid cellular internalization of the M1 but not M23 isoform of AQP4, resulting in AQP4 clustering, enhanced complement-dependent cytotoxicity, and tissue swelling. Here, we report evidence challenging this proposed mechanism of NMO-IgG-mediated pathology. We measured osmotic water permeability by stopped-flow light scattering on plasma membrane vesicles isolated from AQP4-expressing CHO cells, an approach that can detect changes in water permeability as small as 5% and is not confounded by internalization effects. We found similar single-molecule water permeability for M1-AQP4 tetramers and M23-AQP4 clusters (orthogonal arrays of particles, OAPs). Exposure of AQP4 to high concentrations of NMO-IgG from six seropositive NMO patients, and to high-affinity recombinant monoclonal NMO antibodies, did not reduce AQP4 water permeability. Also, NMO-IgG did not reduce water permeability in AQP4-reconstituted proteoliposomes. In transfected cells expressing M1- or M23-AQP4 individually, NMO-IgG caused more rapid internalization of M23- than M1-AQP4. In cells coexpressing both isoforms, M1- and M23-AQP4 comingled in OAPs that were internalized together in response to NMO-IgG. Super-resolution imaging and native gel electrophoresis showed that the size of AQP4 OAPs was not altered by NMO sera or recombinant NMO antibodies. We conclude that NMO-IgG does not: (i) inhibit AQP4 water permeability, (ii) cause preferential internalization of M1-AQP4, or (iii) cause intramembrane AQP4 clustering.

Serum-Positive and -Negative AQP4 Antibody NMO in Chinese Patients

To compare the clinical features of our sero-negative and sero-positive neuromyelitis optica (NMO) patients. Thirty-nine patients with NMO were recruited and analyzed retrospectively. Serum aquaporin 4 (AQP4) antibody status was determined by a cell-based assay. For the sero-negative patients, cerebrospinal fluid (CSF) and serum samples were re-tested using the cell-based assay and an indirect immunofluorescence assay. By the cell-based assay, 30 patients (76.92%, 30/39), were positive for AQP4 antibodies in serum and 37 patients (94.9%, 37/39), had a CSF-positive antibody status. Seven NMO patients (17.9%, 7/39) were sero-negative by the cell-based assay but demonstrated positive CSF results. By indirect immunofluorescence, the remaining two patients, who had no AQP4 antibodies in serum or CSF by the cell-based assay, were positive for IgG antibodies in serum, which selectively targeted the central nervous system microvessels, pia, subpia, Virchow-Robin space, kidney, and stomach. There were no significant differences between the sero-positive and sero-negative NMO groups among their demographic and clinical data. Repeating the test using a different assay or CSF is helpful to clarify whether sero-negative NMO patients do in fact carry AQP4 antibodies.

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

BackgroundThe 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.ObjectiveTo 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.MethodsRetrospective study of 175 Caucasian patients (AQP4-Ab positive in 78.3%).ResultsSeropositive 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.ConclusionThis 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.

Homology between Klebsiella pneumoniae and human aquaporin-4: no evidence for cross-reactivity in neuromyelitis optica. A study on 114 patients

Neuromyelitis optica (NMO) is an autoimmune disorder of the central nervous system (CNS), which predominantly affects the optic nerves and the spinal cord [1, 2]. NMO is associated with antibodies to aquaporin-4 (AQP4), the most abundant water channel in the CNS, in up to 80% of cases [3–7]. There is convincing evidence now that AQP4-Ab are directly involved in the pathogenesis of NMO and its formes frustes, longitudinally extensive myelitis (LETM) and recurrent optic neuritis (rON) [8, 9]. AQP4-Ab is thought to bind to an extracellular domain of the target protein, and loop E was suggested as a probable candidate epitope [10]. The cause of AQP4-Ab autoimmunity is still unknown, but molecular mimicry, i.e. structural similarity between epitopes contained within microbial and host proteins, leading to cross-reactivity of antibodies in the host, has been discussed [11]. We, therefore, performed a BLAST search for bacterial and viral proteins sharing significant homology with loop E of AQP4 (sequence, TGASMNP ARSFGPAVIMGNWENHW) [12, 13]. The Klebsiella pneumoniae subsp. pneumoniae (Kpsp) transmembrane protein KPN_pKPN3p05929 (NCBI reference sequence: YP_001338538.1) produced significant alignment with loop E of human AQP4 (87% positives, 79% identities, 0% gaps) (Fig. 1). In contrast, no bacterial or viral proteins were found that produced significant alignments with the extracellular loops A and C of AQP4. Interestingly, KPN_pKPN3p05929 belongs to the MIP/aquaporin family as predicted by total protein sequence similarities. Moreover, Kpsp infection is not rare, and immunity to Kpsp has been previously implicated in the aetiopathogenesis of a number of autoimmune conditions, such as ankylosing spondylitis or Crohn’s disease [14]. In addition, infection with K. pneumoniae has been reported in association with a first attack of optic neuritis or AQP4-Ab positive LETM in some patients [15, 16]. We, therefore, hypothesized that infection with K. pneumoniae may play a role in the immunopathogenesis of NMO. To explore this hypothesis, we determined frequency and titres of serum IgG, IgM, and IgA antibodies to Kpsp in 48 patients with AQP4-Ab seropositive NMO spectrum disorders (NMOSD) (NMO in 32; LETM in 10; rON in 4; sex ratio [m:f] = 1:23; median age, 44 years; range, 14–69), and in a group of 49 ageand sex-matched AQP4-Ab negative control patients with multiple sclerosis (MS) according to McDonald (RRMS in 41; SPMS in 8). All samples were stored at the Department of Neurology, University of Heidelberg, at -80 C until use, were anonymized prior to testing, and were tested in a blinded fashion. To allow assessment of Kpsp proteins under native expression conditions, we used a commercially available indirect immunofluorescence assay that employs complete Kpsp bacteriae (Euroimmun, Luebeck, Germany). Testing was performed according to the manufacturer’s instructions. We found that the frequency of S. Jarius and K. P. Wandinger contributed equally.

Cytotoxic effect of neuromyelitis optica antibody (NMO-IgG) to astrocytes: An in vitro study

NMO-IgG is a disease-specific autoantibody for neuromyelitis optica (NMO) that binds selectively to aquaporin-4 (AQ4), an astrocytic water channel. The normal distribution of AQP4 coincides with the sites of immunoglobulin and complement deposits in lesions found in autopsy studies. The underlying mechanisms of cytotoxicity by NMO-IgG on astrocytes are not well known. In this study we show that serum samples from seropositive NMO patients (21) induce a higher rate of cell death compared with sera from seronegative NMO (16), relapsing–remitting MS (20) patients, and healthy controls (24) on primary cultures of astrocytes. Similar results were obtained by two different techniques: lactate dehydrogenase release and tetrazolium-based viability assay. Cell death was only observed in the presence of active complement. The complement-dependent cytotoxicity was not accompanied by caspase-3/7 activation or increase in the percentage of apoptotic cells. Our data show that NMO-IgG induces a complement-dependent cytotoxicity of astrocytes in vitro, and suggest that a mechanism of cellular death by necrosis might be implicated in the pathophysiology of NMO.

Acute Disseminating Encephalomyelitis in Neuromyelitis Optica

To report the clinical and radiological features of 2 patients with neuromyelitis optica (NMO) associated with severe acute disseminating encephalomyelitis. The first patient had anti-aquaporin 4 antibodies (NMO-IgG) but no lesion enhancement, in contrast to the second patient who was seronegative for NMO-IgG but had clear lesion enhancement on magnetic resonance imaging. Clinical, laboratory, and radiological analysis of 10 patients presenting with features compatible with an NMO-spectrum disorder, 2 of whom developed acute disseminating encephalomyelitis. Inpatient ward at the Department of Neurology, Hadassah University. Patients admitted during a 1-year period with features compatible with an NMO-spectrum disorder. Medical histories and imaging data were reviewed and serum samples were analyzed for the presence of NMO-IgG. Clinical and paraclinical evidence of brain involvement. Of 10 patients tested, 5 were positive for NMO-IgG. One seropositive and 1 seronegative patient had an acute disseminating encephalomyelitis-like episode. In both cases, the clinical, laboratory, and electroencephalographic findings supported a diagnosis of acute disseminating encephalomyelitis. Magnetic resonance imaging demonstrated extensive bilateral white matter lesions in both patients. Lesions in the seropositive patient were notably lacking in enhancement following gadolinium injection, whereas robust lesion enhancement was observed in the seronegative patient. Acute disseminating encephalomyelitis without lesion enhancement on magnetic resonance imaging may represent a childhood manifestation of seropositive NMO. The lack of enhancement suggests an intact blood-brain barrier and supports a unique mechanism of edema induction due to dysfunction of water channels.