Background

Ependyma forms the epithelial interface boarding the ventricular walls and the spinal cord’s central canal, maintaining crucial central nervous system functions such as the regulation of cerebrospinal fluid (CSF) circulation by synchronous ciliary beating and the monitoring of molecular exchanges between CSF and parenchyma. These functions are dependent of the cellular coupling via gap junction channels.

Neuromyelitis Optica (NMO) is associated with autoantibodies (NMO-IgG), directed against aquaporin 4 (AQP4). NMO-IgG are present in patient’s serum and CSF during attacks, and are known to trigger astrocyte dysfunction leading to demyelination and axonal loss. Interestingly, ependymal cells also express AQP4 and evidences of ependymal alteration have been reported in NMO. Indeed, MRI abnormalities of the ventricles have been reported, and pathological analyses showed AQP4 loss in the ventricular walls of NMO patients.

Objectives

Our aim is to evaluate if NMO-IgG target ependymal cells, and lead to ependymal morphological changes and dysfunctions.

Methods

We used purified NMO-IgG from AQP4 antibodies positive patients’ plasma (NMO-IgG AQP4⁺). IgG from healthy donors (CTRL-IgG) and IgG from AQP4-antibodies negative patients (NMO-IgG AQP4^-) were used as controls. We evaluated ependymal cells on two models: primary ependymal cell cultures and cultured wholemount dissections (“en-face” view of the entire ependyma) of adult rat lateral ventricular walls. We first looked at the effect of different IgGs on the expression of AQP4 and Connexin43, the main gap junction channel expressed by ependymal cells. Then, we assessed the ciliary beating of ependymal cells by analyzing the diffusion of india ink deposited on wholemount preparations. Coupling of ependymal cells in culture was evaluated by measuring the diffusion of Lucifer Yellow (LY), a gap junction specific dye incorporated in cells by scrape loading.

Results

We showed that NMO-IgG AQP4⁺ exposure induced: 1) the delocalization of AQP4 membrane expression and morphological changes of ependymal cells from primary cultures and wholemounts, by contrast different IgG controls had no effect; 2) morphological changes of cilia in primary cultures and alteration of the ciliary dynamic; 3) the alteration of Connexin43 expression and function, demonstrated by the decrease of LY spreading after scrape loading.

Conclusions

These results suggest that NMO-IgG directly induce dysfunctions of ependymal cells, through the perturbation of AQP4 and Cx43 expression and functions.

Background

Glial fibrillar acidic protein (GFAP) autoimmunity is a recently identified disease, at the frontier of auto-immune encephalitis and gliopathies. Clinical features associated to this new entity are still not fully evaluated; especially the risk of relapse and the disability outcome.

Objectives

To report the clinical, biological, imaging features, and the clinical course of a French cohort of patients with GFAP autoantibodies.

Methods

We retrospectively included all patients tested positive for GFAP antibodies since 2017, from two French referral centers (auto-immune encephalitis and rare inflammatory disorders of the brain and the spinal cord). GFAP autoantibodies were detected exclusively in the CSF, by immunohistochemistry and their specificity confirmed by cell-based assay using cells expressing human GFAPα.

Results

We identified 46 patients with GFAP antibodies. Median age at onset was 43 years and men were more affected (30/46). Infectious prodromal symptoms were found in 82% of cases. Other autoimmune diseases were found in 22% of cases and coexisting neural autoantibodies in 11% of cases, including MOG-IgG and AQP4-IgG positive cases. Tumors were present in 24%, and T cell dysfunction in 23% of cases, respectively. The most frequent presentation was acute/subacute menigoencephalitis (85%) with cerebellar dysfunction in 57% of cases. Other/associated clinical presentation included: myelitis (30%), visual tract involvement (35%) and peripheral nervous system involvement (28%). CSF showed pleocytosis (98%), oligoclonal bands (77%) and low glucose level (15%). MRI findings were heterogeneous: radial enhancement was found in 26%, periventricular diffuse T2 hyperintensity in 39%, brainstem involvement in 33%, leptomeningeal enhancement in 23%, and reversible splenial lesions in 4 cases.

39/46 patients have a monophasic course, associated to a good outcome at last follow-up (Rankin Score≤2: 89% at 15,5 months), despite a frequently severe clinical presentation (intensive care unit hospitalization: 42%). Seventy patients were treated with immunotherapy. 11/22 patients showed negativation of GFAP antibodies (median time: 2 months).

Conclusions

GFAP autoimmunity was generally associated to a good outcome and a low risk of relapse. Identification of factors associated to risk of relapse or disability, to monitor immunotherapy, is needed.

Background

Optic neuritis (ON) is a frequent manifestation in aquaporin-4 antibody (AQP4-IgG) seropositive neuromyelitis optica spectrum disorders (NMOSD). Due to limited samples, existing optical coherence tomography (OCT) studies are inconsistent regarding retinal changes in eyes with a history of ON (NMO-ON) and without a history of ON (NMO-NON), and their functional relevance.

Objectives

The CROCTINO (Collaborative Retrospective Study on retinal OCT in Neuromyelitis Optica) project aims to reveal correlates of retinal pathology and to generate hypotheses for prospective OCT studies in NMOSD. The objective of this study was to analyze retinal changes of AQP4-IgG seropositive NMO-ON and NMO-NON eyes in an international cross-sectional OCT dataset.

Methods

Of 656 subjects, we enrolled 283 AQP4-IgG seropositive NMOSD patients and 72 healthy controls (HC) from 22 international expert centers. OCT data was acquired with Spectralis SD-OCT, Cirrus HD-OCT and Topcon 3D OCT-1. Mean thickness for the combined ganglion cell and inner plexiform layer (GCIP) and inner nuclear layer (INL) were calculated from macular volume scans. Clinical, functional and laboratory testing were performed at discretion of each center.

Results

We compared NMO-ON eyes (N = 260), NMO-NON eyes (N = 241) and HC eyes (N = 136). GCIP was reduced in NMO-ON (57.4 ± 12.2 µm) compared with NMO-NON (75.9 ± 7.7 µm; p < 0.001) and HC (81.4 ± 5.7 µm; p < 0.001). NMO-NON had thinner GCIP (p < 0.001) compared with HC. INL was thicker in NMO-ON (40.3 ± 3.9 µm) compared with NMO-NON (38.6 ± 3.9µm; p < 0.001), but not HC (39.4 ± 2.6 µm). Microcystic macular edema were visible in 6.6 % of NMOSD eyes.

Conclusions

AQP4-IgG seropositive NMOSD is characterized by a functionally relevant loss of retinal neuroaxonal content and a - probably inflammatory - increase of INL after ON. Our study further supports the existence of attack-independent damage in the visual system of patients with AQP4-IgG seropositive NMOSD.

Background

To predict the clinical course of myelin oligodendrocyte glycoprotein (MOG)-antibody (Ab)-associated disease (MOGAD) is essential to guide treatment recommendations.

Objectives

We aimed to 1) compare clinical features and disease course, and 2) to evaluate the association of MOG-Ab dynamics and relapses, between children and adults with MOGAD.

Methods

Retrospective study evaluating clinical features of 98 children and 266 adults with MOGAD, between January 2014 and September 2019. To analyse relapses over the whole disease course, a Cox regression analysis for recurrent time-to-event data was performed, introducing treatment as time-dependent covariate. To evaluate dynamics, delta mean fluorescence intensity ratio signal (ΔMFIratio) of MOG-Ab was measured in patients with a minimum time elapsed between two samples of 4 months.

Results

Median age at onset of symptoms was 10.9 (interquartile range 5.4-14.3) years in children and 36.2 (27.7-47.6) in adults. Isolated optic neuritis was the most frequent clinical presentation both in children (40.8%) and adults (55.9%), p=0.013, and acute disseminated encephalomyelitis syndrome was more frequent in children (36.7% vs. 5.6%; p<0.001). Compared to adults, children displayed a better recovery (EDSS ≥3.0 at last follow-up reached only by 10 of 97 [10.3%] vs. 66/247 [26.7%], p<0.001).

In the multivariate analysis, adults were at higher risk of relapse than children (Hazard ratio 1.41, 95%Confidence interval [CI] 1.12-1.78; p=0.003). Among the 124 participants evaluated for MOG-Ab dynamics, 36.3% became seronegative, 60.5% decrease and 3.2% increase the ΔMFIratio. At two years, 64.2% (95%CI 40.9-86.5) of non-relapsing children became MOG-Ab negative compared to 14.1% (95%CI 4.7-38.3) of relapsing ones, log-rank p<0.001, with no differences observed between non-relapsing and relapsing adults, log-rank p=0.280.

Conclusions

MOGAD differs in its clinical presentation at onset, showing a progressive shift in the clinical features across age-groups. Compared to children, adults have a higher risk of relapses and a worse functional recovery. Finally, children with monophasic disease became MOG-Ab negative earlier than relapsing ones, but not in adults. Considering these differences, management and treatment guidelines should be considered independently in children and adults.

Background

Outcomes of coronavirus disease 2019 (COVID-19) in patients with neuromyelitis optica spectrum disorders (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), often treated with immunosuppressive therapies, are still unknown.

Objectives

The objective was to describe the clinical characteristics and outcomes of COVID-19 in patients with neuromyelitis optica and associated disorders and to identify the factors associated with COVID-19 severity.

Methods

We conducted a multi-center, retrospective, observational cohort study among all French expert centers for neuromyelitis optica and related disorders. Patients with NMOSD or MOGAD included in the study received a confirmed or highly suspected diagnosis of COVID-19 between March 1, 2020 and June 30^th, 2020. Main outcome was COVID-19 severity score assessed on a 7-point ordinal scale ranging from 1 (not hospitalized with no limitations on activities) to 7 (death).

Results

Fifteen cases (mean [SD] age: 39.3 [14.3] years, 11 female) were included. Five patients (33.3%) were hospitalized, all receiving rituximab. A 24-year-old patient with positive aquaporine-4 antibody, with obesity as comorbidity, needed mechanical ventilation. Outpatients were receiving anti-CD20 (5), mycophenolate mofetil (3) or azathioprine (3). They were younger (mean [SD] age: 37.0 [13.4] years), with a longer disease duration (mean [SD]: 8.3 [6.3] years) and had a lower EDSS score (median [range] EDSS: 2.5 [0-4]) relative to patients requiring hospitalization (mean [SD] age: 44.0 [16.4] years, mean [SD] disease duration: 5.8 [5.5] years, median [range] EDSS: 4 [0-6.5]).

Conclusions

COVID-19 outcome was overall favorable in this cohort. Larger international studies are needed to identify risk factors of severe COVID-19, however we recommend to maintain preventive measures to limit the risk of contamination with SARS-CoV-2 in this immunocompromised population.

Background

Pathogenic autoantibodies against aquaporin 4 (AQP4) in neuromyelitis optica spectrum disorder (NMOSD) cause central nervous system injury, with subsequent release of astroglial and neuronal proteins such as glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) and Tau into the circulation. N-MOmentum is a randomized, placebo-controlled, double-masked trial of inebilizumab, a B-cell-depleting monoclonal antibody (NCT02200770).

Objectives

Investigate relationships of NfL, UCH-L1, Tau and serum (s)GFAP to disease activity and Expanded Disability Status Scale (EDSS) disability in N-MOmentum trial participants with either AQP4-immunoglobulin G (IgG) seropositive or seronegative NMOSD.

Methods

Serum biomarkers NfL, UCH-L1, Tau and sGFAP were measured using the single molecular array (SIMOA; Quanterix) in 1260 serial and attack-related samples from N-MOmentum participants (n=215) and healthy controls (HC; n=25).

Results

At baseline, biomarkers were elevated in subsets of patients with NMOSD (NfL, 16%; UCH-L1, 6%; Tau, 12%; sGFAP, 29%); NfL and UCH-L1 levels correlated with sGFAP (r=0.53 [p<0.001] and 0.18 [p=0.007]). Baseline elevations were significantly associated with increased attack risk (NfL, hazard ratio [HR] 2.5, p=0.01; UCH-L1, HR 2.8, p=0.039; Tau, HR 2.6, p=0.01; sGFAP, HR 3.03, p<0.001). After controlling for baseline sGFAP in Cox regressions, the other markers were not independently associated with attack risk (all HR <2; p>0.05). In the total cohort, a greater proportion of patients had an attack with placebo than inebilizumab (39% vs 12%). All biomarker levels increased after attacks and median-fold increases from baseline (95% confidence interval) trended higher with placebo than inebilizumab, reaching significance with sGFAP (NfL, 1.49 [0.93–3.37] vs 1.30 [0.84–2.14], p=0.4; UCH-L1, 6.70 [1.59–52.4] vs 1.85 [0.89–23], p=0.12; Tau, 2.19 [0.96–9.46] vs 1.09 [0.40–3.7], p=0.23; sGFAP, 20.2 [4.4–98] vs 1.11 [0.75–24.6], p=0.037). Following attacks, NfL correlated with EDSS score at attack assessments (R=0.55; p<0.001); other biomarkers did not correlate with EDSS score after controlling for NfL levels.

Conclusions

In NMOSD, serum NfL, UCH-L1 and Tau levels were higher than in HC; increased baseline sGFAP levels were associated with greater attack risk. Although sGFAP levels showed the greatest increase following attacks, NfL correlated with attack-related disability.

Background

The N-MOmentum trial of inebilizumab included patients with aquaporin 4-IgG seropositive (AQP4+) or seronegative (AQP4−) neuromyelitis optica spectrum disorder (NMOSD).

Objectives

To report AQP4− participant outcomes in N-MOmentum. .......................................................

Methods

Medical histories and screening data for AQP4− patients were assessed independently by 3 clinical experts before enrollment. Majority decision confirmed diagnoses using the 2006 criteria. Myelin oligodendrocyte glycoprotein-IgG (MOG) serology and annualized attack rates (AARs) were tested post hoc. These observations do not account for bias in estimates of effects on the AAR caused by regression to the mean, introduced by inclusion criteria requiring attacks during the 1 to 2 years before study entry.

Results

Only 18/50 AQP4− patients (36%) were eligible for randomization; 17 were randomized, 4 to placebo (1 MOG+) and 13 to inebilizumab (6 MOG+). Reasons for not enrolling prospective AQP4− NMOSD participants were mainly related to lack of fulfillment of MRI findings required by the 2006 criteria.

Owing to limited patient numbers, we compared the on-study to the pre-study AAR for treated participants to assess treatment effects.

For AQP4− participants (n=17), 40 attacks occurred in 23 patient-years of pre-study follow-up with mean AAR (95% confidence interval) of 1.72 (1.23–2.33). For MOG+ participants (n=7), 16 attacks occurred in 8.3 patient-years of pre-study follow-up with an AAR of 1.93 (1.11–3.14). For double-seronegative participants (n=10), 24 attacks occurred in 15 patient-years of pre-study follow-up with an AAR of 1.60 (1.02–2.38).

After receiving inebilizumab, AARs declined in all groups by the end of the randomized controlled period: AQP4− participants (n=13), 0.09 (0.02–0.26), or 3 attacks in 34.2 patient-years; MOG+ participants (n=6), 0.08 (0.002–0.464), or 1 attack in 12 patient-years; double-seronegative participants (n=7), 0.09 (0.011–0.326), or 2 attacks in 22 patient-years.

The benefit was sustained with longer-term inebilizumab exposure. At 120 days into the open-label period (OLP), during which all participants received inebilizumab, the AAR in AQP4− participants (n=17) remained low (0.069 [0.014–0.202]). No attacks were seen in any AQP4−, MOG+ or double seronegative patient during the OLP.

Conclusions

The N-MOmentum trial provides clinically important insight on the difficulty of correctly diagnosing AQP4− NMOSD and suggests that inebilizumab may have a benefit on AAR in these patients.

Background

Magnetic resonance imaging (MRI) findings in patients with neuromyelitis optica spectrum disorder (NMOSD) have not previously been studied with data from a prospective, randomized controlled study. During N-MOmentum, longitudinal MRIs were performed systematically.

Objectives

To characterize MRI findings in patients with NMOSD in the N-MOmentum study of inebilizumab. .....................

Methods

MRIs of the spinal cord, optic nerve and brain were performed at baseline, within 8 days of an NMOSD attack and at the end of the randomized controlled period (RCP; month 6.5). MRIs were read centrally by two independent, blinded-to-treatment neuroradiologists for new gadolinium-enhancing (Gd)-T1 enhancement events. Attacks were adjudicated by an expert committee.

Results

Complete MRI data were available for 192 (83%) of 230 participants, 42 of whom had an adjudicated attack (22 myelitis, 14 optic neuritis, 6 multi-domain). The remaining 38 patients did not have valid post-baseline MRI scans available for analysis. Inter-rater agreement between the two neuroradiologists for gadolinium-enhancing lesions was 98% for brain, 95% for spinal cord and 90% for optic nerve.

At the time of acute adjudicated NMOSD attacks, new Gd-T1 MRI enhancement corresponding to the affected clinical domain was present in 19/22 myelitis attacks (86%) and 11/14 optic neuritis attacks (79%). At the time of acute optic neuritis attacks, asymptomatic, new Gd-T1 enhancement was simultaneously observed in 4/14 spinal cord MRIs (29%) and 1/14 brain MRIs (7%). At the time of acute myelitis attacks, asymptomatic, new Gd-T1 enhancement was simultaneously observed in 6/22 optic nerve MRIs (27%) and 3/22 brain MRIs (14%).

In the 150 participants without an adjudicated attack, new Gd-T1 MRI enhancements compared with baseline readings were observed in the brain, spinal cord and optic nerve in 3%, 18% and 51% of patients at the end of the RCP, respectively.

Conclusions

At the time of attack, MRI enhancements were highly correlated to the clinical presentations. However, asymptomatic Gd-T1 enhancements were detected outside the symptomatic attack domain in about one-third of cases. Furthermore, subclinical Gd-T1 enhancements were observed in many patients who did not experience clinically overt attacks. Subclinical blood–brain barrier breakdown, particularly in the optic nerve, may be a frequent phenomenon in patients with active NMOSD.

Background

The N-MOmentum trial of inebilizumab included patients with aquaporin 4-IgG seropositive (AQP4+) or seronegative (AQP4−) neuromyelitis optica spectrum disorder (NMOSD).

Objectives

To report AQP4− participant outcomes in N-MOmentum. .......................................................

Methods

Medical histories and screening data for AQP4− patients were assessed independently by 3 clinical experts before enrollment. Majority decision confirmed diagnoses using the 2006 criteria. Myelin oligodendrocyte glycoprotein-IgG (MOG) serology and annualized attack rates (AARs) were tested post hoc. These observations do not account for bias in estimates of effects on the AAR caused by regression to the mean, introduced by inclusion criteria requiring attacks during the 1 to 2 years before study entry.

Results

Only 18/50 AQP4− patients (36%) were eligible for randomization; 17 were randomized, 4 to placebo (1 MOG+) and 13 to inebilizumab (6 MOG+). Reasons for not enrolling prospective AQP4− NMOSD participants were mainly related to lack of fulfillment of MRI findings required by the 2006 criteria.

Owing to limited patient numbers, we compared the on-study to the pre-study AAR for treated participants to assess treatment effects.

For AQP4− participants (n=17), 40 attacks occurred in 23 patient-years of pre-study follow-up with mean AAR (95% confidence interval) of 1.72 (1.23–2.33). For MOG+ participants (n=7), 16 attacks occurred in 8.3 patient-years of pre-study follow-up with an AAR of 1.93 (1.11–3.14). For double-seronegative participants (n=10), 24 attacks occurred in 15 patient-years of pre-study follow-up with an AAR of 1.60 (1.02–2.38).

After receiving inebilizumab, AARs declined in all groups by the end of the randomized controlled period: AQP4− participants (n=13), 0.09 (0.02–0.26), or 3 attacks in 34.2 patient-years; MOG+ participants (n=6), 0.08 (0.002–0.464), or 1 attack in 12 patient-years; double-seronegative participants (n=7), 0.09 (0.011–0.326), or 2 attacks in 22 patient-years.

The benefit was sustained with longer-term inebilizumab exposure. At 120 days into the open-label period (OLP), during which all participants received inebilizumab, the AAR in AQP4− participants (n=17) remained low (0.069 [0.014–0.202]). No attacks were seen in any AQP4−, MOG+ or double seronegative patient during the OLP.

Conclusions

The N-MOmentum trial provides clinically important insight on the difficulty of correctly diagnosing AQP4− NMOSD and suggests that inebilizumab may have a benefit on AAR in these patients.