GV-971 attenuates the progression of neuromyelitis optica in murine models and reverses alterations in gut microbiota and associated peripheral abnormalities.

AIMS: Growing evidence suggests that an imbalanced gut microbiota composition plays a crucial role in the development of neuromyelitis optica spectrum disorders (NMOSD), an inflammatory demyelinating disease primarily affecting the optic nerves and central nervous system (CNS). In light of this, we explored the potential therapeutic benefits of GV-971 in NMOSD. GV-971 is a drug used for treating mild-to-moderate Alzheimer's disease, which targets the gut-brain axis and reduces neuroinflammation. METHODS: To evaluate GV-971's effects, we employed the experimental autoimmune encephalomyelitis (EAE) mouse model to establish NMOSD animal models. This was achieved by injecting NMO-IgG into aged mice (11 months old) or using NMO-IgG along with complement injection and microbubble-enhanced low-frequency ultrasound (MELFUS) techniques in young mice (7 weeks old). We assessed the impact of GV-971 on incidence rate, clinical scores, body weight, and survival, with methylprednisolone serving as a positive control. In NMOSD models of young mice, we analyzed spinal cord samples through H&E staining, immunohistochemistry, and Luxol Fast Blue staining. Fecal samples collected at different time points underwent 16S rRNA gene sequencing, while plasma samples were analyzed using cytokine array and untargeted metabolomics analysis. RESULTS: Our findings indicated that GV-971 significantly reduced the incidence of NMOSD, alleviated symptoms, and prolonged survival in NMOSD mouse models. The NMOSD model exhibited substantial neuroinflammation and injury, accompanied by imbalances in gut microbiota, peripheral inflammation, and metabolic disorders, suggesting a potentially vicious cycle that accelerates disease pathogenesis. Notably, GV-971 effectively reduces neuroinflammation and injury, and restores gut microbiota composition, as well as ameliorates peripheral inflammation and metabolic disorders. CONCLUSIONS: GV-971 attenuates the progression of NMOSD in murine models and reduces neuroinflammation and injury, likely through its effects on remodeling gut microbiota and peripheral inflammation and metabolic disorders.

Targeting chemoattractant chemokine (C-C motif) ligand 2 derived from astrocytes is a promising therapeutic approach in the treatment of neuromyelitis optica spectrum disorders.

Introduction: Aquaporin-4 immunoglobulin G (AQP4-IgG)-induced astrocytes injury is a key mechanism in the pathogenesis of neuromyelitis spectrum disorder (NMOSD), and although CCL2 is involved, its specific role has not been reported. We aimed to further investigate the role and potential mechanisms of CCL2 in AQP4-IgG-induced astrocyte injury. Methods: First, we evaluated CCL2 levels in paired samples of subject patients by automated microfluidic platform, Ella®. Second, we knock down astrocyte's CCL2 gene in vitro and in vivo to define the function of CCL2 in AQP4-IgG-induced astrocyte injury. Third, astrocyte injury and brain injury in live mice were assessed by immunofluorescence staining and 7.0T MRI, respectively. Western blotting and high-content screening were conducted to clarify the activation of inflammatory signaling pathways, and changes in CCL2 mRNA and cytokine/chemokines were measured by qPCR technique and flow cytometry, respectively. Results: There were greatly higher CSF-CCL2 levels in NMOSD patients than that in other non-inflammatory neurological diseases (OND) groups. Blocking astrocyte CCL2 gene expression can efficiently mitigate AQP4-IgG-induced damage in vitro and in vivo. Interestingly, prevention of CCL2 expression could decrease other inflammatory cytokines released, including IL-6 and IL-1ß. Our data suggest that CCL2 involves in the initiation and plays a pivotal role in AQP4-IgG-damaged astrocytes. Discussion: Our results indicate that CCL2 may serve as a promising candidate target for inflammatory disorder therapy, including NMOSD.

Aquaporin-4 in Neuromyelitis Optica Spectrum Disorders: A Target of Autoimmunity in the Central Nervous System.

Since the discovery of a specific autoantibody in patients with neuromyelitis optica spectrum disorder (NMOSD) in 2004, the water channel aquaporin-4 (AQP4) has attracted attention as a target of autoimmune diseases of the central nervous system. In NMOSD, the autoantibody (NMO-IgG) binds to the extracellular loops of AQP4 as expressed in perivascular astrocytic end-feet and disrupts astrocytes in a complement-dependent manner. NMO-IgG is an excellent marker for distinguishing the disease from other inflammatory demyelinating diseases, such as multiple sclerosis. The unique higher-order structure of AQP4-called orthogonal arrays of particles (OAPs)-as well as its subcellular localization may play a crucial role in the pathogenesis of the disease. Recent studies have also demonstrated complement-independent cytotoxic effects of NMO-IgG. Antibody-induced endocytosis of AQP4 has been suggested to be involved in this mechanism. This review focuses on the binding properties of antibodies that recognize the extracellular region of AQP4 and the characteristics of AQP4 that are implicated in the pathogenesis of NMOSD.

Clinico-epidemiologic characteristics of optic neuritis in a tertiary eye centre in Eastern India based on the status of serum aquaporin-4 antibody.

PURPOSE: To elucidate the clinico-epidemiologic characteristics of optic neuritis based on the status of serum aquaporin-4 antibody (AQP4-Ab) in patients with optic neuritis (ON). METHODS: Medical records of 106 patients with ON and a follow-up of 3 years were reviewed. For each patient, the following data were extracted: medical history, findings of the ocular examination, brain, orbital or spinal MRI, and serological tests for AQP4. The ON was classified as typical or atypical based on disc examination and improvement in vision after intravenous methylprednisolone (IVMP). The clinical findings (typical or atypical), disease course, and outcomes were analyzed according to the serostatus of the ON. RESULTS: 10 patients ((9.4%) were seropositive for AQP4-Ab; all had atypical ON. 96 patients (91%) were seronegative for AQP4-Ab: 36 atypical ON and 60 typical ON. Profound visual impairment at presentation was seen in all patients. However, at the end of the study period, seropositive and seronegative atypical ON had poor visual outcomes as compared to seronegative typical ON (P = 0.002). Five seropositive and four seronegative patients with atypical ON developed transverse myelitis. Bilateral disease with relapse was more in seropositive patients (80%); however, seronegative with atypical ON also had bilateral presentation and relapse in 42% and 41%, respectively. CONCLUSION: AQP4-Ab seropositive patients mostly present with atypical features such as bilateral recurrent ON, poor visual outcome, and increased incidence of transverse myelitis. However, atypical clinical features can also be seen in seronegative ON with a poor visual outcome and a recalcitrant course.

An Autopsy Confirmed Neuromyelitis Optica Spectrum Disorder with Extensive Brain White Matter Lesion and Optic Neuritis but Intact Spinal Cord, Clinically Mimicking a Secondary Progressive Multiple Sclerosis-like Course.

A 57-year-old woman presented with optic neuritis with repeated clinical symptoms of focal demyelination of the cerebral white matter and brain stem for 14 years. At the end of the patient's course, the clinical signs mimicked secondary progressive multiple sclerosis, but whether it was caused by interferon administration or neuromyelitis optica spectrum disorders (NMOSD) - or a combination of both or others - was unclear. Histopathological findings indicated the etiology to be NMOSD, with no apparent plaque in spinal cord specimens. This case suggests that an accurate clinical diagnosis requires serum anti-aquaporin 4 antibody measurements as well as an autopsy examination.

The association between dietary total antioxidant capacity and NMO-IgG seropositivity in patients with neuromyelitis optica spectrum disorder.

OBJECTIVES: There is growing evidence highlighting the role of environmental risk factors of NMO-IgG seropositivity in patients with neuromyelitis optica spectrum disorder (NMOSD). The present study investigated the possible association between dietary total antioxidant capacity (TAC) and NMO-IgG seropositivity in NMOSD patients. METHODS: Fifty-six patients with a definite diagnosis of NMOSD were included in the study. Data on patients' age, gender, height, weight, cigarette smoking status, and alcohol consumption were collected and recorded. Body mass index (BMI) was also calculated. In addition, dietary habits of patients were evaluated using an adjusted semi-quantitative food frequency questionnaire (FFQ) that consists of 168 food items. Dietary TAC was calculated using the oxygen radical absorption capacity (ORAC) method. Enzyme-linked immunosorbent assay (ELISA) method was used to determine the NMO-IgG serum status. The association between dietary TAC and odds of NMO-IgG seropositivity was measured using the logistic regression analysis. RESULTS: The mean of dietary TAC was 8362.8 (µmolTE/1000 kcal) in seronegative patients and 6609.9 (µmolTE/1000 kcal) in seropositive patients and had a significant difference between the mentioned groups of patients (P: 0.02). An inverse association was found between dietary TAC and odds of NMO-IgG seropositivity in all three regression models. The higher dietary intake of antioxidant resulted in significant findings as follows: 92% (95% CI: 0.01-0.53), 97% (95% CI: 0.00-0.34), and 97% (95% CI: 0.00-0.32) lower odds of NMO-IgG seropositivity in the fourth quartiles of the first, the second, and the third regression model, respectively. Moreover, the inverse association between fruit intake and odds of NMO-IgG seropositivity was significant in the third quartile (OR:0.10; 95%CI: 0.01-0.97). CONCLUSION: The present study indicated a significant inverse association between dietary TAC and NMO-IgG seropositivity of NMOSD patients. As no definite treatment can be offered for NMOSD and nutrition is a modifiable factor in this regard, specification of dietary factors affecting the risk of NMOSD is of great value.

The possible role of Interleukin-6 as a regulator of insulin sensitivity in patients with neuromyelitis optica spectrum disorder.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is associated with inflammatory mediators that may also trigger downstream signaling pathways leading to reduce insulin sensitivity. METHODS: We aimed to determine the risk association of hyperinsulinemia in NMOSD patients with seropositive AQP4-IgG and the serum levels of interleukin (IL)-6 and IL-17A compared with the control group. Serum levels of metabolic (Insulin, Fasting Blood Sugar (FBS), lipid profile) and inflammatory (IL-6 and IL-17) markers were assessed in 56 NMOSD patients and 100 controls. RESULTS: Hyperinsulinemia was more prevalent in NMOSD patients independent of age, sex and body mass index (BMI) (48.2% vs. 26%, p = 0.005) compared to control group. After adjusting age, sex and BMI, there was significant association between lower insulin sensitivity (IS) and NMOSD risk (95% CI: Beta = 0.73, 0.62 to 0.86, p = 0.0001). Circulating levels of IL-6 and IL-17 were higher in NMOSD patients, and only IL-6 had an effect modifier for the association between lower insulin sensitivity and NMOSD risk. CONCLUSIONS: Our data suggests that inflammatory pathogenesis of NMOSD leads to hyperinsulinemia and increases the risk of insulin resistance.

Experimental mouse model of NMOSD produced by facilitated brain delivery of NMO-IgG by microbubble-enhanced low-frequency ultrasound in experimental allergic encephalomyelitis mice.

Although optic neuritis and myelitis are the core clinical characteristics of neuromyelitis optica spectrum disorders (NMOSD), appropriate animal models of NMOSD with myelitis and optic neuritis are lacking. we developed a mouse model of NMOSD by intravenously injecting 100 µg neuromyelitis optica immunoglobulin G antibody (NMO-IgG) and complement into experimental allergic encephalomyelitis (EAE) mice after reversible blood-brain barrier (BBB) opening by microbubble-enhanced low-frequency ultrasound (MELFUS). Animals were assessed by histopathology. We found noticeable inflammation and demyelination concomitant with the loss of aquaporin-4 (AQP4) and glial fibrillary acidic protein (GFAP) expression in the spinal cord, brain and optic nerve, as well as human IgG and C9neo deposition. Thus, with the help of MELFUS, we established an NMOSD mouse model with the core lesions of NMOSD by applying a considerably lower dose of human NMO-IgG, which may help identify the pathogenesis and facilitate the development of other neuroimmune disease models in the future.

Effect of NMO-IgG on the interleukin-6 cascade in astrocytes via activation of the JAK/STAT3 signaling pathway.

AIMS: Astrocytes expressing the aquaporin-4 (AQP4) water channel are pathogenic, disease specific immunoglobulins (IgG) found in neuromyelitis optica spectrum disorder (NMOSD), referred to as NMO-IgG, which targets astrocytic AQP4. The interleukin-6 (IL-6) signaling when astrocytes were exposed to NMO-IgG present in the serum of NMOSD patients was evaluated. MAIN METHODS: Serum or human-IgG from NMOSD or healthy controls were exposed to astrocytes. The selectivity and immuno-pathological consequences of Ig binding to surface epitopes were measured by confocal microscopy. Astrocytes were exposed to medium, IL-6, soluble IL-6 receptor (sIL-6R), IL-6 + sIL-6R (IL-6/R), NMO-IgG or control-IgG, NMO-IgG + IL-6/R. The expression of key proteins in IL-6 signaling pathway, IL-6 cytokine and mRNA levels were evaluated by western blotting, enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. KEY FINDINGS: Serum or NMO-IgG from NMOSD patients both induced the rapid downregulation of AQP4 expression on the surface of astrocytes. Stimulation of astrocytes with NMO-IgG, IL-6/R, and NMO-IgG + IL-6/R resulted in the enhancement of IL-6 mRNA expression. Meanwhile, the exogenous addition of NMO-IgG elicited an inflammatory transcriptional response that involved signaling through the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) pathway. Inhibition of the IL-6/JAK/STAT3 pathway with the JAK1/2 specific inhibitor, AZD1480, reversed the associated increase of IL-6. SIGNIFICANCE: Our findings suggest that NMO-IgG can stimulate the astrocytic JAK1/2/STAT3-dependent inflammatory response, which represents one of the important events in NMO pathogenesis. Inhibition of the JAK1/2 signaling pathway may be a novel promising therapy for NMOSD.

Repetitive intrathecal injection of human NMO-IgG with complement exacerbates disease severity with NMO pathology in experimental allergic encephalomyelitis mice.

Neuromyelitis optica (NMO) is recognized as a different CNS autoimmune disease from multiple sclerosis (MS). Whether NMO-IgG contributes directly to the pathogenesis of NMO or is just a serologic marker of autoimmune responses of the disease needs to be clarified. We created MOG-induced experimental autoimmune encephalomyelitis (EAE) mice by passively transferring NMO-IgG to model the pathogenic findings in NMO patients. The mice were divided into three groups and administered intrathecal PBS, human complement with IgG from normal subjects, or IgG from AQP4(+) patients on days 8 and 11 after immunization. The EAE scores of EAE mice with intrathecal NMO-IgG injection were significantly elevated 14 days post-immunization. All of the mice were sacrificed for brain and spinal cord pathology analysis on day 21 post-immunization. Compared to mice given normal human IgG, EAE mice injected with NMO-IgG had markedly decreased AQP4 and glial fibrillary acidic protein (GFAP) expression and fluorescent intensity in the brain and spinal cord but more scattered deposition of complement (C9neo). Thus, our studies not only support the pathogenic role of NMO-IgG with complement in NMO disease but also provide a platform for the development of future therapeutics.

Clinical presentation of optic neuritis with autoantibodies anti-myelin oligodendrocyte glycoprotein.

PURPOSE:: Myelin oligodendrocyte glycoprotein autoantibodies are associated with certain optic neuritis. Little data are known about the specificity of the initial ophthalmologic presentation. METHODS:: A monocentric retrospective study (2013-2017) of all patients diagnosed with myelin oligodendrocyte glycoprotein+ optic neuritis in a tertiary ophthalmologic unit was conducted. The primary objective was to define the clinical ophthalmologic description of the first episode. The secondary objective was to evaluate the evolution and final diagnosis. RESULTS:: A total of nine patients were included. There was no female predominance (sex ratio f/m = 0.8). At the first optic neuritis episode, the average age was 39.3 years (17-67 years, standard deviation: 18.4). Initial visual acuity was low (+1.07logMAR, standard deviation: 0.77); 5 eyes out of 15 had visual acuity +2logMAR or worse. Optic neuritis was mostly painful (8/9) and bilateral (6/9) but asymmetric. Optic disk swelling was reported in 9/15 eyes and 7/9 patients and was significantly associated with lower visual acuity in the acute phase (+1.46logMAR, standard deviation: 0.67 vs +0.5, standard deviation: 0.55; p = 0.03). After a mean observation period of 3.3 years (0.6-9.4 years, standard deviation: 3.4), median visual acuity was 0.05logMAR. All five patients were followed up for more than 1 year (5.4 years, standard deviation: 3.2) had 3-8 relapses (mean: 4.4, standard deviation: 2.1; annualized relapse rate: 1.2, standard deviation: 0.9). Final diagnosis was chronic relapsing idiopathic optic neuritis (n = 4), clinically isolated optic neuritis (n = 3), and neuromyelitis optica spectrum disorder aquaporin 4- (n = 2). CONCLUSION:: Myelin oligodendrocyte glycoprotein+ optic neuritis has an atypical clinical presentation compared with multiple sclerosis and neuromyelitis optica spectrum disorder aquaporin 4+. Its evolution is closer to neuromyelitis optica spectrum disorder aquaporin 4+, with a better visual outcome.

Neuromyelitis optica spectrum disorder: Pathogenesis, treatment, and experimental models.

Neuromyelitis optica (NMO) and NMO spectrum disorder (NMOSD) are inflammatory CNS syndromes mainly involving the optic nerve and/or spinal cord and characterized by the presence of serum aquaporin-4 immunoglobulin G antibodies (AQP4-IgG). The pathology of NMOSD is complicated, while therapies for NMOSD are limited and only partially effective in most cases. This review article focuses on the main pathology of NMOSD involving AQP4-IgG and lymphocyte function. We also review the existing therapeutic methods and potential new treatments. Experimental NMO animal models are crucial for further research into NMO pathology and treatment. However, no AQP4-IgG-immunized animals have been reported. The establishment of NMO models is therefore difficult and primarily depends on the generation of transgenic mice or transcranial manipulation using human or monoclonal mouse anti-AQP4 antibodies. Advantages and disadvantages of each model are discussed.

Anti-aquaporin-4 titer is not predictive of disease course in neuromyelitis optica spectrum disorder: A multicenter cohort study.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disease associated with a serological antibody to aquaporin-4 (AQP4) detectable in up to 80% of patients. The enzyme-linked immunosorbent assay (ELISA) is one of the most popular methods of testing for anti-AQP4 antibodies that results with a titer in which < 3 Units/ml is negative, 3-5 is borderline and 5+ is positive. The value of the positive titer in predicting long term disease course is currently unknown. METHODS: This is a retrospective analysis of NMOSD patients from five centers around the world: Baltimore, USA, Philadelphia, USA, Shanghai, China, Berlin, Germany, and Medellin, Columbia, where ELISA titers on anti-AQP4 antibody testing is available. Inclusion criteria include a diagnosis of NMOSD and seropositive anti-AQP4 antibody test with titer = /> 3 Units/ml. Patients were stratified into three groups by titer: 3-30 Units/ml (low), 31-100 Units/ml (medium), and 101+ Units/ml (high). Demographic factors such as age at onset, race, and sex were collected along with clinical features such as annualized relapse rate, duration of disease, location of relapses, and treatment history. RESULTS: A total of 139 NMOSD patients met criteria for inclusion in this study, stratified into three groups by titer: 42 subjects with low titers of 3-30 Units/ml, 30 subjects with medium titers of 31-100 Units/ml and 67 subjects with high titers of 101 or greater ELISA Units/ml. The average age at onset, sex and race distribution were not significantly different among the groups. The number of patients untreated in each group was similar (< 25%) as was the average annualized relapse rate (0.591-0.821 relapses/year). With an average of 10 years follow up, the average disability level was not different among the three titer groups (EDSS range 3.03-3.48). The distribution of lesions, as well as their preventive treatment regimens did not differ significantly. CONCLUSION: Beyond a positive/borderline/negative result, the titer of the anti-AQP4 antibody ELISA assay is not predictive in the disease course for patients with NMOSD. Low titer patients experience the same disease course as medium-titer and high-titer anti-AQP4 antibody patients with NMOSD.

[Clinical characteristics of neuromyelitis optica spectrum disorders associated with syringomyelia].

Objective: To analyze the clinical characteristics of neuromyelitis optica spectrum disorders (NMOSD) associated with syringomyelia (SML). Methods: The clinical manifestations, laboratory parameters and imaging findings of 7 patients with NMOSD associated with SML during June 2008 to August 2016 from The Third Affiliated Hospital of Sun Yat-sen University were retrospectively analyzed. Results: Six patients were female and 1 was male, with ages ranging from 27-67 years, the course of the disease was 3-12 years, recurrence was 2-7 times, all the patients were cerebrospinal fluid oligoclonal bands (CSF OCB) negative, 5 patients were positive for aquaporin-4-antibody/NMO-IgG. Sensory and motor dysfunction, bowel or bladder dysfunction were the common clinical manifestation, and pain was a significant symptom. Syringomyelia was predominantly located in C4-T10, cavity length 2-6 mm, diameter 0.8-3.6 mm; 5 had lobes involvement and 6 had long segmental spinal cord involvement. Conclusions: NMOSD associated with SML had a high frequency of occurrence in female, with the clinical characteristics of limb pain, easy progression, high recurrence rate and disability rate. The anti AQP4 antibody were commonly seen in these patients. Syringomyelia was predominantly located in the lower cervical and upper thoracic spinal cord, the lobar and longitudinally extensive transverse myelitis were frequently found in patients with NMOSD associated with SML.

Role of AQP4 Antibody Serostatus and its Prediction of Visual Outcome in Neuromyelitis Optica: A Systematic Review and Meta-Analysis.

Backgroud: Neuromyelitis optica (NMO) is an autoimmune inflammatory disorder, which is characterized by severe attacks of optic neuritis and myelitis. Antibodies (Ab) to aquaporin-4 (AQP4) (or NMO-IgG) as a serological biomarker of NMO have been widespread used. Nevertheless, some NMO patients remain seronegative for AQP4-Ab and/or have no detected optic nerve involvement. In addition, no consensus exists on the association between AQP4-Ab serostatus and visual outcome in NMO. To drive a more precise estimate of this postulated relationship, a metaanalysis was performed based on existing relevant studies. METHODS: Studies were searched by PubMed and MEDLINE up to March 2016. Study quality was assessed, and meta-analysis was conducted using the RevMan 5.1. Odds ratios with 95% confidence interval were calculated and funnel plot was applied to assess the potential publication bias. RESULTS: In a total of 1288 relevant studies, 18 studies satisfied the eligibility criteria and were included in the systemic review. Only 9 studies appeared eligible for the meta-analysis, together including 624 AQP4-Ab-positive and 119 AQP4-Ab-negative NMO patients. The results revealed associations between AQP4-Ab seropositivity and visual impairment in NMO (OR, 3.16; 95% CI, 1.09, 9.19; P = 0.03). The results of subgroup analyses based on different methods of AQP-4 detection also showed significantly differences between AQP4-Ab seropositivity and visual impairment in NMO, especially in CBA subgroup. CONCLUSION: This meta-analysis indicates that AQP4-Ab serostatus has the positive with poor visual outcome in NMO.

MOG-IgG in NMO and related disorders: a multicenter study of 50 patients. Part 4: Afferent visual system damage after optic neuritis in MOG-IgG-seropositive versus AQP4-IgG-seropositive patients.

BACKGROUND: Antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) have been reported in patients with aquaporin-4 antibody (AQP4-IgG)-negative neuromyelitis optica spectrum disorders (NMOSD). The objective of this study was to describe optic neuritis (ON)-induced neuro-axonal damage in the retina of MOG-IgG-positive patients in comparison with AQP4-IgG-positive NMOSD patients. METHODS: Afferent visual system damage following ON was bilaterally assessed in 16 MOG-IgG-positive patients with a history of ON and compared with that in 16 AQP4-IgG-positive NMOSD patients. In addition, 16 healthy controls matched for age, sex, and disease duration were analyzed. Study data included ON history, retinal optical coherence tomography, visual acuity, and visual evoked potentials. RESULTS: Eight MOG-IgG-positive patients had a previous diagnosis of AQP4-IgG-negative NMOSD with ON and myelitis, and eight of (mainly recurrent) ON. Twenty-nine of the 32 eyes of the MOG-IgG-positive patients had been affected by at least one episode of ON. Peripapillary retinal nerve fiber layer thickness (pRNFL) and ganglion cell and inner plexiform layer volume (GCIP) were significantly reduced in ON eyes of MOG-IgG-positive patients (pRNFL = 59 ± 23 µm; GCIP = 1.50 ± 0.34 mm3) compared with healthy controls (pRNFL = 99 ± 6 µm, p < 0.001; GCIP = 1.97 ± 0.11 mm3, p < 0.001). Visual acuity was impaired in eyes after ON in MOG-IgG-positive patients (0.35 ± 0.88 logMAR). There were no significant differences in any structural or functional visual parameters between MOG-IgG-positive and AQP4-IgG-positive patients (pRNFL: 59 ± 21 µm; GCIP: 1.41 ± 0.27 mm3; Visual acuity = 0.72 ± 1.09 logMAR). Importantly, MOG-IgG-positive patients had a significantly higher annual ON relapse rate than AQP4-IgG-positive patients (median 0.69 vs. 0.29 attacks/year, p = 0.004), meaning that on average a single ON episode caused less damage in MOG-IgG-positive than in AQP4-IgG-positive patients. pRNFL and GCIP loss correlated with the number of ON episodes in MOG-IgG-positive patients (p < 0.001), but not in AQP4-IgG-positive patients. CONCLUSIONS: Retinal neuro-axonal damage and visual impairment after ON in MOG-IgG-positive patients are as severe as in AQP4-IgG-positive NMOSD patients. In MOG-IgG-positive patients, damage accrual may be driven by higher relapse rates, whereas AQP4-IgG-positive patients showed fewer but more severe episodes of ON. Given the marked damage in some of our MOG-IgG-positive patients, early diagnosis and timely initiation and close monitoring of immunosuppressive therapy are important.

MOG-IgG in NMO and related disorders: a multicenter study of 50 patients. Part 3: Brainstem involvement - frequency, presentation and outcome.

BACKGROUND: Myelin oligodendrocyte glycoprotein antibodies (MOG-IgG) are present in a subset of aquaporin-4 (AQP4)-IgG-negative patients with optic neuritis (ON) and/or myelitis. Little is known so far about brainstem involvement in MOG-IgG-positive patients. OBJECTIVE: To investigate the frequency, clinical and paraclinical features, course, outcome, and prognostic implications of brainstem involvement in MOG-IgG-positive ON and/or myelitis. METHODS: Retrospective case study. RESULTS: Among 50 patients with MOG-IgG-positive ON and/or myelitis, 15 (30 %) with a history of brainstem encephalitis were identified. All were negative for AQP4-IgG. Symptoms included respiratory insufficiency, intractable nausea and vomiting (INV), dysarthria, dysphagia, impaired cough reflex, oculomotor nerve palsy and diplopia, nystagmus, internuclear ophthalmoplegia (INO), facial nerve paresis, trigeminal hypesthesia/dysesthesia, vertigo, hearing loss, balance difficulties, and gait and limb ataxia; brainstem involvement was asymptomatic in three cases. Brainstem inflammation was already present at or very shortly after disease onset in 7/15 (47 %) patients. 16/21 (76.2 %) brainstem attacks were accompanied by acute myelitis and/or ON. Lesions were located in the pons (11/13), medulla oblongata (8/14), mesencephalon (cerebral peduncles; 2/14), and cerebellar peduncles (5/14), were adjacent to the fourth ventricle in 2/12, and periaqueductal in 1/12; some had concomitant diencephalic (2/13) or cerebellar lesions (1/14). MRI or laboratory signs of blood-brain barrier damage were present in 5/12. Cerebrospinal fluid pleocytosis was found in 11/14 cases, with neutrophils in 7/11 (3-34 % of all CSF white blood cells), and oligoclonal bands in 4/14. Attacks were preceded by acute infection or vaccination in 5/15 (33.3 %). A history of teratoma was noted in one case. The disease followed a relapsing course in 13/15 (87 %); the brainstem was involved more than once in 6. Immunosuppression was not always effective in preventing relapses. Interferon-beta was followed by new attacks in two patients. While one patient died from central hypoventilation, partial or complete recovery was achieved in the remainder following treatment with high-dose steroids and/or plasma exchange. Brainstem involvement was associated with a more aggressive general disease course (higher relapse rate, more myelitis attacks, more frequently supratentorial brain lesions, worse EDSS at last follow-up). CONCLUSIONS: Brainstem involvement is present in around one third of MOG-IgG-positive patients with ON and/or myelitis. Clinical manifestations are diverse and may include symptoms typically seen in AQP4-IgG-positive neuromyelitis optica, such as INV and respiratory insufficiency, or in multiple sclerosis, such as INO. As MOG-IgG-positive brainstem encephalitis may take a serious or even fatal course, particular attention should be paid to signs or symptoms of additional brainstem involvement in patients presenting with MOG-IgG-positive ON and/or myelitis.

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

BACKGROUND: Antibodies to myelin oligodendrocyte glycoprotein (MOG-IgG) have been suggested to play a role in a subset of patients with neuromyelitis optica and related disorders. OBJECTIVE: To assess (i) the frequency of MOG-IgG in a large and predominantly Caucasian cohort of patients with optic neuritis (ON) and/or myelitis; (ii) the frequency of MOG-IgG among AQP4-IgG-positive patients and vice versa; (iii) the origin and frequency of MOG-IgG in the cerebrospinal fluid (CSF); (iv) the presence of MOG-IgG at disease onset; and (v) the influence of disease activity and treatment status on MOG-IgG titers. METHODS: 614 serum samples from patients with ON and/or myelitis and from controls, including 92 follow-up samples from 55 subjects, and 18 CSF samples were tested for MOG-IgG using a live cell-based assay (CBA) employing full-length human MOG-transfected HEK293A cells. RESULTS: MOG-IgG was detected in 95 sera from 50 patients with ON and/or myelitis, including 22/54 (40.7 %) patients with a history of both ON and myelitis, 22/103 (21.4 %) with a history of ON but no myelitis and 6/45 (13.3 %) with a history of longitudinally extensive transverse myelitis but no ON, and in 1 control patient with encephalitis and a connective tissue disorder, all of whom were negative for AQP4-IgG. MOG-IgG was absent in 221 further controls, including 83 patients with AQP4-IgG-seropositive neuromyelitis optica spectrum disorders and 85 with multiple sclerosis (MS). MOG-IgG was found in 12/18 (67 %) CSF samples from MOG-IgG-seropositive patients; the MOG-IgG-specific antibody index was negative in all cases, indicating a predominantly peripheral origin of CSF MOG-IgG. Serum and CSF MOG-IgG belonged to the complement-activating IgG1 subclass. MOG-IgG was present already at disease onset. The antibodies remained detectable in 40/45 (89 %) follow-up samples obtained over a median period of 16.5 months (range 0-123). Serum titers were higher during attacks than during remission (p < 0.0001), highest during attacks of simultaneous myelitis and ON, lowest during acute isolated ON, and declined following treatment. CONCLUSIONS: To date, this is the largest cohort studied for IgG to human full-length MOG by means of an up-to-date CBA. MOG-IgG is present in a substantial subset of patients with ON and/or myelitis, but not in classical MS. Co-existence of MOG-IgG and AQP4-IgG is highly uncommon. CSF MOG-IgG is of extrathecal origin. Serum MOG-IgG is present already at disease onset and remains detectable in the long-term course. Serum titers depend on disease activity and treatment status.

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

BACKGROUND: A subset of patients with neuromyelitis optica spectrum disorders (NMOSD) has been shown to be seropositive for myelin oligodendrocyte glycoprotein antibodies (MOG-IgG). OBJECTIVE: To describe the epidemiological, clinical, radiological, cerebrospinal fluid (CSF), and electrophysiological features of a large cohort of MOG-IgG-positive patients with optic neuritis (ON) and/or myelitis (n = 50) as well as attack and long-term treatment outcomes. METHODS: Retrospective multicenter study. RESULTS: The sex ratio was 1:2.8 (m:f). Median age at onset was 31 years (range 6-70). The disease followed a multiphasic course in 80 % (median time-to-first-relapse 5 months; annualized relapse rate 0.92) and resulted in significant disability in 40 % (mean follow-up 75 ± 46.5 months), with severe visual impairment or functional blindness (36 %) and markedly impaired ambulation due to paresis or ataxia (25 %) as the most common long-term sequelae. Functional blindess in one or both eyes was noted during at least one ON attack in around 70 %. Perioptic enhancement was present in several patients. Besides acute tetra-/paraparesis, dysesthesia and pain were common in acute myelitis (70 %). Longitudinally extensive spinal cord lesions were frequent, but short lesions occurred at least once in 44 %. Fourty-one percent had a history of simultaneous ON and myelitis. Clinical or radiological involvement of the brain, brainstem, or cerebellum was present in 50 %; extra-opticospinal symptoms included intractable nausea and vomiting and respiratory insufficiency (fatal in one). CSF pleocytosis (partly neutrophilic) was present in 70 %, oligoclonal bands in only 13 %, and blood-CSF-barrier dysfunction in 32 %. Intravenous methylprednisolone (IVMP) and long-term immunosuppression were often effective; however, treatment failure leading to rapid accumulation of disability was noted in many patients as well as flare-ups after steroid withdrawal. Full recovery was achieved by plasma exchange in some cases, including after IVMP failure. Breakthrough attacks under azathioprine were linked to the drug-specific latency period and a lack of cotreatment with oral steroids. Methotrexate was effective in 5/6 patients. Interferon-beta was associated with ongoing or increasing disease activity. Rituximab and ofatumumab were effective in some patients. However, treatment with rituximab was followed by early relapses in several cases; end-of-dose relapses occurred 9-12 months after the first infusion. Coexisting autoimmunity was rare (9 %). Wingerchuk's 2006 and 2015 criteria for NMO(SD) and Barkhof and McDonald criteria for multiple sclerosis (MS) were met by 28 %, 32 %, 15 %, 33 %, respectively; MS had been suspected in 36 %. Disease onset or relapses were preceded by infection, vaccination, or pregnancy/delivery in several cases. CONCLUSION: Our findings from a predominantly Caucasian cohort strongly argue against the concept of MOG-IgG denoting a mild and usually monophasic variant of NMOSD. The predominantly relapsing and often severe disease course and the short median time to second attack support the use of prophylactic long-term treatments in patients with MOG-IgG-positive ON and/or myelitis.

Human Aquaporin-4 and Molecular Modeling: Historical Perspective and View to the Future.

Among the different aquaporins (AQPs), human aquaporin-4 (hAQP4) has attracted the greatest interest in recent years as a new promising therapeutic target. Such a membrane protein is, in fact, involved in a multiple sclerosis-like immunopathology called Neuromyelitis Optica (NMO) and in several disorders resulting from imbalanced water homeostasis such as deafness and cerebral edema. The gap of knowledge in its functioning and dynamics at the atomistic level of detail has hindered the development of rational strategies for designing hAQP4 modulators. The application, lately, of molecular modeling has proved able to fill this gap providing a breeding ground to rationally address compounds targeting hAQP4. In this review, we give an overview of the important advances obtained in this field through the application of Molecular Dynamics (MD) and other complementary modeling techniques. The case studies presented herein are discussed with the aim of providing important clues for computational chemists and biophysicists interested in this field and looking for new challenges.