Blood parameters in pediatric myelin oligodendrocyte glycoprotein antibody-associated disorders.

BACKGROUND AND OBJECTIVES: Patients with myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGAD) clinically present e.g. with acute disseminated encephalomyelitis (ADEM), optic neuritis (ON), transverse myelitis (TM) or aquaporin-4-IgG (AQP4-IgG) negative neuromyelitis optica spectrum disorders (NMOSD)-like phenotypes. We aimed to analyze and compare blood parameters in children with MOGAD, AQP4-IgG-positive NMOSD (hence NMOSD), multiple sclerosis (MS) and healthy controls (HC). METHODS: We evaluated differences in complete blood counts (CBC), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR) and C-reactive protein (CRP) between these four groups and within the groups between clinical attack, acute treatment and remission. RESULTS: Our cohort consisted of 174 children and adolescents with a total of 550 timepoints: 66 patients had MOGAD (202 timepoints), 11 NMOSD (76 timepoints), 58 MS (219 timepoints) and 39 were HC (53 timepoints). At clinical attack, leukocyte counts were elevated in MOGAD compared to remission (p < 0.001) and compared to all other groups (p < 0.001). NLR was high in MOGAD and NMOSD, and PLR was high in NMOSD, however, after correction for multiple testing these findings did not remain significant. While glucocorticoids caused an increase of leukocyte counts and NLR in NMOSD and MS, these values remained stable during acute treatment in MOGAD. In remission, NLR normalized in MOGAD, while it stayed high in NMOSD. PLR increased in NMOSD and was significantly higher compared to all other groups. DISCUSSION: Some blood parameters, mainly leukocyte and differential counts, might help clinicians to evaluate disease activity, differentiate relapses from pseudo-relapses and even distinguish between different disease entities.

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

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

Blood sphingolipid as a novel biomarker in patients with neuromyelitis optica spectrum disorder.

BACKGROUND: Sphingolipids are signaling molecules and structural components of the axolemma and myelin sheath. Plasma sphingolipid levels may reflect disease status of neuromyelitis optica spectrum disorder (NMOSD). We aimed to examine plasma sphingolipids as disease severity biomarkers for NMOSD and compare their characteristics with those of serum neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP). METHODS: We measured plasma sphingolipids, sNfL, and sGFAP levels in NMOSD cases with anti-aquaporin-4-antibody. An unbiased approach, partial least square discriminant analysis (PLS-DA), was utilized to determine whether sphingolipid profiles differ according to the disease state of NMOSD (presence, moderate-to-severe disability [Expanded Disease Severity Scale, (EDSS) > 3.0], and relapses). RESULTS: We investigated 81 patients and 10 controls. PLS-DA models utilizing sphingolipids successfully differentiated patients with EDSS > 3.0, but failed to identify the presence of disease and relapses. Ceramide-C14-a significant contributor to differentiating EDSS > 3.0-positively correlated with EDSS, while its levels were independent of age and the presence of relapses. This characteristic was unique from those of sNfL and sGFAP, which were affected by age and relapses as well as EDSS. CONCLUSION: Plasma sphingolipids may be useful NMOSD biomarkers for disability with distinct characteristics compared to sNfL and sGFAP.

Identification of potential biomarkers for neuromyelitis optica by quantitative proteomics.

OBJECTIVE: Neuromyelitis optica (NMO) was a serious autoimmune inflammatory condition affecting the central nervous system. Currently, there was a lack of diagnostic biomarkers for AQP4-IgG-negative NMO patients. METHODS: A comparative proteomic analysis was conducted on the CSF of 10 patients with NMO and 10 patients with non-inflammatory neurological disorders (NND) using tandem mass tagging technology. Differentially expressed proteins (DEPs) were analyzed using bioinformatic methods. The candidate proteins were then validated through ELISAs in a subsequent cohort of 160 samples, consisting of paired CSF and plasma samples from 50 NMO patients, CSF samples from 30 NND patients, and plasma samples from 30 healthy individuals. RESULTS: We identified 389 proteins via proteomics, screening 79 DEPs. NCAM1, SST and AHSG were selected as candidate molecules for further validation. Compared to NND patients, there were decreased levels of AHSG in CSF and increased levels of NCAM1 and SST in NMO patients. The ELISA results revealed significantly higher levels of AHSG, SST and NCAM1 in the CSF of the NMO group compared to the NND group. Similarly, the serum levels of these three proteins were also higher in the NMO group compared to the healthy control group. It was found that serum NCAM1 levels significantly decreased in patients with non-relapsed NMO compared to patients with relapsed NMO and CSF NCAM1 level increased in patients with bilateral NMO compared to patients with unilateral NMO. Furthermore, CSF SST levels increased in AQP4 antibody-positive NMO patients compared to AQP4 antibody-negative patients. INTERPRETATION: CSF NCAM1, serum NCAM1 and serum SST may serve as potential biomarkers for NMO patients and aid in the diagnosis of AQP4 antibody-negative NMO patients.

Severe disease exacerbation after mRNA COVID-19 vaccination unmasks suspected multiple sclerosis as neuromyelitis optica spectrum disorder: a case report.

BACKGROUND: Since the beginning of the COVID-19 pandemic and development of new vaccines, the issue of post-vaccination exacerbation or manifestation of demyelinating central nervous system (CNS) disorders has gained increasing attention. CASE PRESENTATION: We present a case of a 68-year-old woman previously diagnosed with multiple sclerosis (MS) since the 1980s who suffered a rapidly progressive severe sensorimotor paraparesis with loss of bladder and bowel control due to an acute longitudinal extensive transverse myelitis (LETM) after immunization with the mRNA Pfizer-BioNTech COVID-19 vaccine. Detection of Aquaporin-4-antibodies (AQP4) in both serum and CSF led to diagnosis of AQP4-antibody positive neuromyelitis optica spectrum disorder (NMOSD). Treatment with intravenous corticosteroids and plasmapheresis led to a slight improvement of the patient's symptoms. CONCLUSIONS: Pathogenic mechanisms of post-vaccination occurrence of NMOSD are still unknown. However, cases like this should make aware of rare neurological disorders manifesting after vaccination and potentially contribute to improvement of management of vaccinating patients with inflammatory CNS disorders in the future. So far two cases of AQP4-antibody positive NMOSD have been reported in association with viral vector COVID-19 vaccines. To our knowledge, we report the first case of AQP4-antibody positive NMOSD after immunization with an mRNA COVID-19-vaccine.

Distinct expression and clinical value of aquaporin 4 in children with hand, foot and mouth disease caused by enterovirus 71.

Brain dysfunction is a prerequisite for critical complications in children with hand, foot, and mouth disease (HFMD). Aquaporin 4 (AQP-4) may be involved in the pathological process of cerebral oedema and injury in children with severe and critical HFMD. This study aimed to assess the association of AQP-4 with the severity of enterovirus 71 (EV71)-associated HFMD. Children with EV71-infected HFMD were divided into a common group (clinical stage 1), a severe group (clinical stage 2), and a critical group (clinical stage 3) according to Chinese guidelines. The levels of AQP-4, interleukin-6 (IL-6), norepinephrine (NE), and neuron-specific enolase (NSE) before and after treatment were tested. Serum AQP-4, IL-6, NE, and NSE levels showed significant differences among the critical, severe, and common groups before and after treatment (P < 0.01). No significant differences in AQP-4 levels in cerebrospinal fluid (CSF) were observed between the critical and severe groups before and after treatment, but the CSF AQP-4 levels in these two groups were higher than those in the common group before treatment (P < 0.01). Serum AQP-4 levels, but not CSF AQP-4 levels, closely correlated with serum IL-6, NE, and NSE levels. These results suggest that the level of AQP-4 in serum, but not in CSF, is a candidate biomarker for evaluating the severity and prognosis of EV71-associated HFMD.

Astrocytic outer retinal layer thinning is not a feature in AQP4-IgG seropositive neuromyelitis optica spectrum disorders.

BACKGROUND: Patients with anti-aquaporin-4 antibody seropositive (AQP4-IgG+) neuromyelitis optica spectrum disorders (NMOSDs) frequently suffer from optic neuritis (ON) leading to severe retinal neuroaxonal damage. Further, the relationship of this retinal damage to a primary astrocytopathy in NMOSD is uncertain. Primary astrocytopathy has been suggested to cause ON-independent retinal damage and contribute to changes particularly in the outer plexiform layer (OPL) and outer nuclear layer (ONL), as reported in some earlier studies. However, these were limited in their sample size and contradictory as to the localisation. This study assesses outer retinal layer changes using optical coherence tomography (OCT) in a multicentre cross-sectional cohort. METHOD: 197 patients who were AQP4-IgG+ and 32 myelin-oligodendrocyte-glycoprotein antibody seropositive (MOG-IgG+) patients were enrolled in this study along with 75 healthy controls. Participants underwent neurological examination and OCT with central postprocessing conducted at a single site. RESULTS: No significant thinning of OPL (25.02±2.03 µm) or ONL (61.63±7.04 µm) were observed in patients who were AQP4-IgG+ compared with patients who were MOG-IgG+ with comparable neuroaxonal damage (OPL: 25.10±2.00 µm; ONL: 64.71±7.87 µm) or healthy controls (OPL: 24.58±1.64 µm; ONL: 63.59±5.78 µm). Eyes of patients who were AQP4-IgG+ (19.84±5.09 µm, p=0.027) and MOG-IgG+ (19.82±4.78 µm, p=0.004) with a history of ON showed parafoveal OPL thinning compared with healthy controls (20.99±5.14 µm); this was not observed elsewhere. CONCLUSION: The results suggest that outer retinal layer loss is not a consistent component of retinal astrocytic damage in AQP4-IgG+ NMOSD. Longitudinal studies are necessary to determine if OPL and ONL are damaged in late disease due to retrograde trans-synaptic axonal degeneration and whether outer retinal dysfunction occurs despite any measurable structural correlates.

Frequency of New Silent MRI Lesions in Myelin Oligodendrocyte Glycoprotein Antibody Disease and Aquaporin-4 Antibody Neuromyelitis Optica Spectrum Disorder.

Importance: In multiple sclerosis, magnetic resonance imaging (MRI) new silent lesions contribute to the diagnostic criteria, have prognostic value, and are used in treatment monitoring; but in aquaporin-4 antibody neuromyelitis optica spectrum disorder (AQP4-NMOSD), they are rare between attacks. Their frequency and their association with relapses in adults with myelin oligodendrocyte glycoprotein antibody disease (MOGAD) are still unclear. Objective: To examine the frequency and characteristics of MRI new silent lesions in MOGAD and AQP4-NMOSD. Design, Setting, and Participants: This retrospective cohort study analyzed clinical and MRI data of 404 patients with MOGAD or AQP4-NMOSD between February 1, 1994, and April 1, 2021; data were prospectively recorded on the Oxford NMOSD clinical database under follow-up. The study was conducted at the Oxford National Referral Center for NMOSD. Participants included patients with MOGAD and AQP4-NMOSD who were treated within the Oxford National NMO Specialist Service. Exposures: Seropositive MOGAD and AQP4-NMOSD patients who had MRIs during attacks and the remission phase of their disease. Main Outcomes and Measures: Frequency of new silent lesions detected by either attack MRIs (during the acute clinical event) or remission MRIs (performed outside of a relapse and at least 3 months from last attack). Median time to next relapse in the presence of definite (reference MRI performed at least 4 weeks from last attack onset), probable (reference MRI performed during last attack), and no new silent lesions on remission MRIs was also evaluated. Results: One hundred eighty-two MOGAD patients and 222 AQP4-NMOSD patients were included. Of the MOGAD patients, 113 (62%) were female, median age at onset was 28 years (range, 2-72), and median follow-up was 52 months (range, 11-253). Of the AQP4-NMOSD patients, 189 (85%) were female, median age at onset was 43 years (range, 2-82), and median follow-up was 87.5 months (range, 11-260). MOGAD patients had 296 attack MRI sessions and 167 remission MRI sessions. New attack silent lesions were found in 97 of 296 (33%) attack MRI sessions, whereas new remission silent lesions were found in 5 of 167 (3.0%) remission MRI sessions. Median time from remission scan to the next relapse in the presence of definite or probable new remission lesions was 2 months (IQR, 1-6), whereas in the absence of any new remission lesions it was 73 months (IQR, 20-104; hazard ratio, 23.86; 95% CI, 7.51-75.79; P < .001). AQP4-NMOSD patients had 470 attack MRI sessions and 269 remission MRI sessions. New attack silent lesions were detected in 88 of 470 (18.7%) attack MRI sessions, whereas new remission silent lesions were found in 7 of 269 (2.6%) remission MRI sessions. Median time from remission scan to the next relapse in the presence of definite or probable new remission lesions was 5 months (IQR, 2-6), whereas in the absence of any new remission lesions it was 85 months (IQR, 29-167; hazard ratio, 21.23; 95% CI, 8.05-53.65; P < .001). Conclusions and Relevance: In contrast to that reported in multiple sclerosis, results of this cohort study suggest that new remission silent lesions are rare on follow-up scans in MOGAD and AQP4-NMOSD and appear to indicate a high risk of imminent relapse.

Cytoprotective IgG antibodies in sera from a subset of patients with AQP4-IgG seropositive neuromyelitis optica spectrum disorder.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system. Most NMOSD patients are seropositive for immunoglobulin G (IgG) autoantibodies against astrocyte water channel aquaporin-4 (AQP4), called AQP4-IgG. AQP4-IgG binding to aquaporin-4 causes complement-dependent cytotoxicity (CDC), leading to inflammation and demyelination. Here, CDC was measured in AQP4-expressing cells exposed to human complement and heat-inactivated sera from 108 AQP4-IgG seropositive NMOSD subjects and 25 non-NMOSD controls. AQP4-IgG positive sera produced a wide range of CDC, with 50% maximum cytotoxicity produced by as low as 0.2% serum concentration. Unexpectedly, 58 samples produced no cytotoxicity, and of those, four sera were cytoprotective against cytotoxic AQP4-IgG. Cytoprotection was found against different cytotoxic monoclonal AQP4-IgGs and NMOSD patient sera, and in primary astrocyte cultures. Mechanistic studies revealed that the protective factor is an IgG antibody that did not inhibit complement directly, but interfered with binding of cytotoxic AQP4-IgG to AQP4 and consequent C1q binding and complement activation. Further studies suggested that non-pathogenic AQP4-IgG, perhaps with altered glycosylation, may contribute to reduced or ineffectual binding of cytotoxic AQP4-IgG, as well as reduced cell-surface AQP4. The presence of natural cytoprotective antibodies in AQP4-IgG seropositive sera reveals an added level of complexity in NMOSD disease pathogenesis, and suggests the potential therapeutic utility of 'convalescent' serum or engineered protective antibody to interfere with pathogenic antibody in AQP4-IgG seropositive NMOSD.

Paraneoplastic AQP4-IgG-Seropositive Neuromyelitis Optica Spectrum Disorder Associated With Teratoma: A Case Report and Literature Review.

OBJECTIVES: To assess a case of paraneoplastic aquaporin-4 (AQP4)-immunoglobulin G (IgG)-seropositive neuromyelitis optica spectrum disorder (NMOSD) associated with teratoma and determine whether it is a paraneoplastic neurologic disorder. METHODS: A single case study and literature review of 5 cases. RESULTS: A 27-year-old woman presented with diplopia, facial nerve palsy, paraplegia, sensory dysfunction of lower limbs, dysuria, nausea, and vomiting. Spinal cord MRI detected an extensive longitudinal lesion in the spinal cord, and brain MRI detected abnormal lesions in the right cerebral peduncle and tegmentum of the pons. CSF analysis revealed positive oligoclonal IgG bands (OCBs). The patient tested positive for AQP4-IgG, confirming a diagnosis of NMOSD. An abdominal CT scan detected an ovarian tumor. After steroid therapy and tumor removal, the patient progressively improved, with only mild sensory dysfunction. Histopathologic analysis of the tumor revealed a teratoma and the presence of glial fibrillary acidic protein (GFAP)+ neural tissue with AQP4 immunoreactivity, accompanied by lymphocyte infiltration. Including the present case, there have been 6 reported cases of AQP4-IgG-seropositive NMOSD associated with ovarian teratoma (mean onset age, 32.7 years). Of these patients, 5 (83%) presented with nausea and/or vomiting, positive OCB, and dorsal brainstem involvement. Pathologic analyses of the teratoma were available in 5 cases, including the present case, revealing neural tissue with AQP4 immunoreactivity and lymphocyte infiltration in all cases. CONCLUSIONS: This study suggests that ovarian teratoma may trigger the development of AQP4-IgG-seropositive NMOSD. Further studies are needed to elucidate the pathogenesis of teratoma-associated NMOSD.

Serum neurofilament light chain and glial fibrillary acidic protein in AQP4-IgG-seropositive neuromyelitis optica spectrum disorders and multiple sclerosis: A cohort study.

We investigated the serum neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP) levels in a cohort of Chinese patients with neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS) in relation to clinical disease course and treatment. sNfL and sGFAP levels were determined by ultrasensitive single molecule array (Simoa) assay in patients with NMOSD (n = 102) and MS (n = 98) and healthy controls (HCs; n = 84). Notably, 13 patients with NMOSD and 27 patients with MS were enrolled in the 1-year follow-up cohort. Levels were compared with data such as clinical course, disease duration, Expanded Disability Status Scale (EDSS) score, and lesions on MRI. Higher levels of sNfL and sGFAP were found in subjects with NMOSD and MS than in HCs (sNfL, median 12.11, 17.5 vs. 8.88 pg/ml, p < .05; sGFAP, median 130.2, 160.4 vs. 80.01 pg/ml, p < .05). Moreover, sNfL levels were higher in the relapse phase of MS than in the relapse phase of NMOSD (30.02 vs. 14.57 pg/ml, p < .05); sGFAP levels were higher in the remission phase of MS than in the remission phase of NMOSD (159.8 vs. 124.5 pg/ml, p < .01). A higher sGFAP/sNfL quotient at relapse differentiated NMOSD from MS. Multivariate analyses indicated that sGFAP levels were associated with the EDSS score in NMOSD (p < .05). At the 1-year follow-up, sNfL and sGFAP levels were both decreased in NMOSD patients in remission, while only sNfL levels were decreased in MS patients in remission. sGFAP and sNfL are potential blood biomarkers for diagnosing and monitoring NMOSD and MS.

EBI2-expressing B cells in neuromyelitis optica spectrum disorder with AQP4-IgG: Association with acute attacks and serum cytokines.

Epstein-Barr virus-induced G-protein coupled receptor 2 (EBI2) is important in regulating B cell activation. We investigated whether EBI2 expression on B cells is associated with acute attacks in neuromyelitis optica spectrum disorder with aquaporin-4 IgG (AQP4-IgG(+) NMOSD). Blood samples were collected from patients with AQP4-IgG(+) NMOSD, multiple sclerosis (MS), and patients without inflammatory demyelinating diseases (non-IDD controls). CD19+ B cells and CD4+ T cells were analyzed for surface expression of EBI2. Serum cytokine levels were also analyzed. The EBI2+CD19+ to EBI2-CD19+ cell ratio was significantly higher in patients with AQP4-IgG(+) NMOSD enrolled within 2 months of an attack than in those with non-IDDs (p = 0.007) and MS (p = 0.003). Patients with AQP4-IgG(+) NMOSD enrolled within 2 months of an attack had a higher EBI2+CD19+ cell frequency than patients with AQP4-IgG(+) NMOSD enrolled 2 months after a recent attack (p = 0.001). The EBI2+CD19+ cell frequency was positively correlated with interleukin (IL)-6 and IL-10. EBI2 expression on B cells could be associated with acute attacks of AQP4-IgG(+) NMOSD, possibly through IL-6- or IL-10-related pathways.

Aquaporin-4 Removal from the Plasma Membrane of Human Müller Cells by AQP4-IgG from Patients with Neuromyelitis Optica Induces Changes in Cell Volume Homeostasis: the First Step of Retinal Injury?

Aquaporin-4 (AQP4) is the target of the specific immunoglobulin G autoantibody (AQP4-IgG) produced in patients with neuromyelitis optica spectrum disorders (NMOSD). Previous studies demonstrated that AQP4-IgG binding to astrocytic AQP4 leads to cell-destructive lesions. However, the early physiopathological events in Müller cells in the retina are poorly understood. Here, we investigated the consequences of AQP4-IgG binding to AQP4 of Müller cells, previous to the inflammatory response, on two of AQP4's key functions, cell volume regulation response (RVD) and cell proliferation, a process closely associated with changes in cell volume. Experiments were performed in a human retinal Müller cell line (MIO-M1) exposed to complement-inactivated sera from healthy volunteers or AQP4-IgG positive NMOSD patients. We evaluated AQP4 expression (immunofluorescence and western blot), water permeability coefficient, RVD, intracellular calcium levels and membrane potential changes during hypotonic shock (fluorescence videomicroscopy) and cell proliferation (cell count and BrdU incorporation). Our results showed that AQP4-IgG binding to AQP4 induces its partial internalization, leading to the decrease of the plasma membrane water permeability, a reduction of swelling-induced increase of intracellular calcium levels and the impairment of RVD in Müller cells. The loss of AQP4 from the plasma membrane induced by AQP4-IgG positive sera delayed Müller cells' proliferation rate. We propose that Müller cell dysfunction after AQP4 removal from the plasma membrane by AQP4-IgG binding could be a non-inflammatory mechanism of retinal injury in vivo, altering cell volume homeostasis and cell proliferation and consequently, contributing to the physiopathology of NMOSD.

Prolonged B-cell depletion after rituximab in AQP4-IgG-positive neuromyelitis optica spectrum disorder.

Rituximab (a B-cell depleting monoclonal antibody) is increasingly utilized for treatment of different immune-mediated neurologic disorders, including aquaporin-4-IgG-positive neuromyelitis optica spectrum disorder (AQP4-IgG-NMOSD). After an initial treatment course, the drug is generally reinfused when peripheral blood B-cells levels re-increase >1% (usually after 6-12 months), or at fixed pre-planned 6-month intervals. We describe the unusual case of a 40-year-old woman with AQP4-IgG-NMOSD who showed a prolonged B-cell depletion for nearly five years after a single rituximab reinfusion. In similar rare patients with exceptionally long-lasting B-cell depletion, rituximab reinfusions at fixed pre-planned intervals would result in unnecessary treatment-related risks and health-care expenses.

Molecular Level Characterization of Circulating Aquaporin-4 Antibodies in Neuromyelitis Optica Spectrum Disorder.

OBJECTIVE: To determine whether distinct aquaporin-4 (AQP4)-IgG lineages play a role in neuromyelitis optica spectrum disorder (NMOSD) pathogenesis, we profiled the AQP4-IgG polyclonal serum repertoire and identified, quantified, and functionally characterized distinct AQP4-IgG lineages circulating in 2 patients with NMOSD. METHODS: We combined high-throughput sequencing and quantitative immunoproteomics to simultaneously determine the constituents of both the B-cell receptor (BCR) and the serologic (IgG) anti-AQP4 antibody repertoires in the peripheral blood of patients with NMOSD. The monoclonal antibodies identified by this platform were recombinantly expressed and functionally characterized in vitro. RESULTS: Multiple antibody lineages comprise serum AQP4-IgG repertoires. Their distribution, however, can be strikingly different in polarization (polyclonal vs pauciclonal). Among the 4 serum AQP4-IgG monoclonal antibodies we identified in 2 patients, 3 induced complement-dependent cytotoxicity in a model mammalian cell line (p < 0.01). CONCLUSIONS: The composition and polarization of AQP4-IgG antibody repertoires may play an important role in NMOSD pathogenesis and clinical presentation. Here, we present a means of coupling both cellular (BCR) and serologic (IgG) antibody repertoire analysis, which has not previously been performed in NMOSD. Our analysis could be applied in the future to clinical management of patients with NMOSD to monitor disease activity over time as well as applied to other autoimmune diseases to facilitate a deeper understanding of disease pathogenesis relative to autoantibody clones.

Pain, Depression, and Quality of Life in Neuromyelitis Optica Spectrum Disorder: A Cross-Sectional Study of 166 AQP4 Antibody-Seropositive Patients.

OBJECTIVES: To evaluate prevalence, clinical characteristics, and predictors of pain, depression, and their impact on the quality of life (QoL) in a large neuromyelitis optica spectrum disorder (NMOSD) cohort. METHODS: We included 166 patients with aquaporin-4-seropositive NMOSD from 13 tertiary referral centers. Patients received questionnaires on demographic and clinical characteristics, PainDetect, short form of Brief Pain Inventory, Beck Depression Inventory-II, and Short Form 36 Health Survey. RESULTS: One hundred twenty-five (75.3%) patients suffered from chronic NMOSD-associated pain. Of these, 65.9% had neuropathic pain, 68.8% reported spasticity-associated pain and 26.4% painful tonic spasms. Number of previous myelitis attacks (OR = 1.27, p = 0.018) and involved upper thoracic segments (OR = 1.31, p = 0.018) were the only predictive factors for chronic pain. The latter was specifically associated with spasticity-associated pain (OR = 1.36, p = 0.002). More than a third (39.8%) suffered from depression, which was moderate to severe in 51.5%. Pain severity (OR = 1.81, p < 0.001) and especially neuropathic character (OR = 3.44, p < 0.001) were associated with depression. Pain severity and walking impairment explained 53.9% of the physical QoL variability, while depression and walking impairment 39.7% of the mental QoL variability. No specific medication was given to 70.6% of patients with moderate or severe depression and 42.5% of those with neuropathic pain. Two-thirds (64.2%) of patients with symptomatic treatment still reported moderate to severe pain. CONCLUSIONS: Myelitis episodes involving upper thoracic segments are main drivers of pain in NMOSD. Although pain intensity was lower than in previous studies, pain and depression remain undertreated and strongly affect QoL. Interventional studies on targeted treatment strategies for pain are urgently needed in NMOSD.

Epstein-Barr virus infection in a woman with aquaporin-4 seropositive neuromyelitis optica.

Neuromyelitis optica spectrum disorders (NMOSD) are characterised by pathological antibodies to aquaporin-4 water channels of astrocytes, resulting in severe brain and spinal cord injury. Serological evidence suggests that Epstein-Barr virus (EBV) reactivation may contribute to their pathogenesis. We describe an unusual case of a woman with fever, rash and headache preceding an Aquaporin-4 antibody positive longitudinally extensive transverse myelitis. EBV was detected in her cerebrospinal fluid by polymerase chain reaction assay. This case highlights the potential role of EBV in the pathogenesis of NMOSD.

Serum Neurofilament to Magnetic Resonance Imaging Lesion Area Ratio Differentiates Spinal Cord Infarction From Acute Myelitis.

BACKGROUND AND PURPOSE: The diagnosis of spontaneous spinal cord infarction (SCI) is limited by the lack of diagnostic biomarkers and MRI features that often overlap with those of other myelopathies, especially acute myelitis. We investigated whether the ratio between serum neurofilament light chain levels and MRI T2-lesion area (neurofilament light chain/area ratio-NAR) differentiates SCI from acute myelitis of similar severity. METHODS: We retrospectively identified Mayo Clinic patients (January 1, 2000-December 31, 2019) with (1) SCI, (2) AQP4 (aquaporin 4)-IgG or MOG (myelin oligodendrocyte glycoprotein)-IgG-associated myelitis at disease clinical presentation, or (3) idiopathic transverse myelitis from a previously identified population-based cohort of patients seronegative for AQP4-IgG and MOG-IgG. Serum neurofilament light chain levels (pg/mL) were assessed at the Verona University (SIMOA, Quanterix) in a blinded fashion on available stored samples obtained ≤3 months from myelopathy presentation. For each patient, the largest spinal cord lesion area (mm2) was manually outlined by 2 independent raters on sagittal T2-weighted MRI images, and the mean value was used to determine NAR (pg/[mL·mm2]). RESULTS: Forty-eight patients were included SCI, 20 (definite, 11; probable, 6; possible, 3); acute myelitis, 28 (AQP4-IgG-associated, 17; MOG-IgG-associated, 5; idiopathic transverse myelitis, 6). The median expanded disability status scale score (range) at myelopathy nadir were 7.75 (2-8.5) and 5.5 (2-8), respectively. Serum neurofilament light chain levels (median [range] pg/mL) in patients with SCI (188 [14.3-2793.4]) were significantly higher compared with patients with AQP4-IgG-associated myelitis (37 [0.8-6942.9]), MOG-IgG-associated myelitis (45.8 [4-283.8]), and idiopathic transverse myelitis (15.6 [0.9-217.8]); P=0.01. NAR showed the highest accuracy for identification of SCI versus acute myelitis with values ≥0.35 pg/(mL·mm2) yielding 86% specificity and 95% sensitivity (area under the curve=0.93). The positive and negative likelihood ratios were 6.67 and 0.06, respectively. NAR remained independently associated with SCI after adjusting for age, gender, immunotherapy before sampling, and days from myelopathy symptoms onset to sampling (P=0.0007). CONCLUSIONS: NAR is a novel and promising clinical biomarker for differentiation of SCI from acute myelitis.

Leakage of astrocyte-derived extracellular vesicles in stress-induced exhaustion disorder: a cross-sectional study.

Patients with stress-induced exhaustion disorder (SED) demonstrate cognitive dysfunction similar to patients with minor traumatic brain injury (TBI). We have previously detected elevated concentrations of astrocyte-derived extracellular vesicles (EVs) in patients with TBI. As such, we hypothesized that astrocyte-derived EVs could be higher in patients with SED than in patients with major depressive disorder (MDD) and healthy controls. Patients with SED (n = 31), MDD (n = 31), and healthy matched controls (n = 61) were included. Astrocyte-derived EVs (previously known as microparticles) were measured in plasma with flow cytometry and labeled against glial fibrillary acidic protein (GFAP) and aquaporin 4 (AQP4). In addition, platelet EVs and their CD40 ligand expression were measured. Patients with SED had significantly higher concentrations of AQP4 and GFAP-positive EVs and EVs co-expressing AQP4/GFAP than patients with MDD and healthy controls. Patients with MDD had significantly higher concentrations of GFAP-positive EVs and EVs co-expressing AQP4/GFAP than healthy controls. Platelet EVs did not differ between groups. CD40 ligand expression was significantly higher in patients with SED and MDD than in controls. In conclusion, the present study suggests that patients with SED, and to some extent, patients with MDD, have increased leakage of astrocyte-derived EVs through the blood-brain barrier.