Abstract Background Neuromyelitis optica spectrum disorders (NMOSD) are associated with a high burden of depression, pain, and physical disability, all of which significantly impair quality of life. At the same time, discussions on the cost-effectiveness of treatment strategies are gaining importance. However, it is not yet known whether specific symptom burdens are particularly cost-driving. This study aims to provide a comprehensive cost analysis considering depression and pain to optimise future healthcare strategies. Methods This prospective cross-sectional multicentre study was conducted at twelve centres of the Neuromyelitis Optica Study Group (NEMOS). Over a three-year period, 115 NMOSD patients were recruited. Disease-related costs, pain, and depression were assessed using standardised questionnaires. A generalised linear model analysis and graphical sub-cost analysis were performed to identify key cost drivers. The robustness of our findings was confirmed using two independent depression rating scales. Results In our sample of 115 patients, 77% suffered from chronic pain with a median pain intensity of 4.0 on the numeric rating scale (NRS). Moreover, 56% of patients reported depressive symptoms. In multivariate regression analysis, depression emerged as a significant predictor of total costs (p < 0.001) alongside the EDSS score (p < 0.001) and age (p = 0.004). In contrast, pain was not significantly influencing total costs (p = 0.057), despite being reported by the majority of patients. Graphical analyses highlighted informal costs as the main cost driver in patients with increasing depressive symptoms. Conclusions Depressive symptoms are not only common in NMOSD patients but also represent a major cost driver alongside neurological disability. Addressing these symptoms is essential for optimal patient care and may help reduce the socioeconomic burden.

Background:Autoimmunity is a key clinical feature in both post-infectious Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and Post-Acute Sequelae of COVID (PASC). Passive transfer of immunoglobulins from patients' sera into mice induces some clinical features of PASC. However, the physiological effects of immunoglobulins on cellular alterations remain elusive. In this study, we tested the potential effects of immunoglobulins from ME/CFS patients on endothelial cell dysfunction. Methods:We have isolated immunoglobulins from 106 individuals, including ME/CFS (n = 39), PCS-CFS (n = 15), MS (n = 20) patients, and healthy controls (n = 41). Protein composition of the isolated immune complexes was studied using mass spectrometry. The effect of isolated immune complexes on mitochondria was evaluated using confocal microscopy and a Seahorse XFe96 Extracellular Flux Analyzer, and the impact on inflammatory cytokine secretion was studied using a multiplex bead-based assay. Results:Here, we demonstrate that IgG isolated from post-infectious ME/CFS patients selectively induces mitochondrial fragmentation in human endothelial cells and alters cellular energetics. This effect is lost upon cleavage of IgG into its Fab and Fc fragments. The digested Fab fragment from ME/CFS alone was able to alter the cellular energetics, resembling the effect of intact IgG. IgG from post-infectious ME/CFS, including post-COVID ME/CFS patients, induced distinct but separate cytokine secretion profiles in healthy PBMCs. Proteomics analysis of IgG-bound immune complexes revealed significant changes in immune complexes from ME/CFS patients, affecting extracellular matrix organization, whereas those from post-COVID ME/CFS patients pointed to alterations in hemostasis and blood clot regulation. Conclusions:We demonstrate that IgGs from ME/CFS patients carry a chronic protective stress response that promotes mitochondrial adaptation via fragmentation, without altering mitochondrial ATP generation capacity in endothelial cells. Together, these results highlight a potential pathogenic role of IgG in post-infectious ME/CFS and point to novel therapeutic strategies targeting antibody-mediated metabolic dysregulation.

BackgroundPost-COVID Syndrome (PCS) is characterized by a variety of symptoms including fatigue and impaired physical function. The aim of the ACUQiG-study was to investigate the therapeutic effects and safety of a self-care program combining acupressure and Qigong on physical function in PCS patients with post-infectious fatigue.MethodsIn this two-arm, open-label randomized controlled study, patients with confirmed SARS-CoV-2 infection and persisting fatigue and ≥3 other typical PCS symptoms >12 weeks were enrolled. Patients were randomized to an intervention group receiving an 8-week daily self-applied acupressure regimen performed at home plus twice-weekly online Qigong sessions, or to a control group receiving no study intervention in the first 16 weeks. Both groups received written self-care advice on complementary medicine treatments and continued routine care. The primary outcome was physical function at 8 weeks measured via the SF-36 Physical Functioning Subscale (SF-36 PFS). Secondary outcomes included fatigue measured by the Chalder Fatigue Scale (CFS), responder analysis, and safety outcomes.ResultsA total of 235 participants (85.1% women; mean age 42.1 years) were randomized (n = 118 intervention, n = 117 controls). At week 8, the adjusted between-group difference in SF-36 PFS was 4.2 points (95% CI −0.9 to 9.4; p = 0.109) with a mean of 55.4 (51.8–59.1) in the intervention group vs. 51.2 (47.6–54.9) in the control group. Responder analysis (≥10-point improvement) suggested a favorable trend for the intervention group (58.9% vs. 46.3%; odds ratio 1.69 (95% CI, 0.98 to 2.92, p = 0.058). The intervention group showed slightly greater improvements in Chalder Fatigue Scale scores [mean at week 8, 21.4 (95% CI 20.2–22.6) vs. 23.2 (95% CI 22.0–24.3), p = 0.040] compared to the control group. Overall, the self-applied study intervention was safe, but aggravation of preexisting symptoms occurred.ConclusionBoth groups improved over time; the addition of acupressure and Qigong to a self-care advice leaflet did not provide a statistically significant or clinically relevant improvement in physical function compared to the leaflet alone. Further high-quality clinical trials are needed to investigate the effects of multimodal self-care programs for managing PCS-related fatigue and physical function.Clinical trial registrationClinicaltrials.gov identifier: NCT05289154, https://clinicaltrials.gov/ct2/show/NCT05289154. First registered 21.03.2022.

BACKGROUND:Differences in brain atrophy rates between patients with aquaporin-4 IgG-positive neuromyelitis optica spectrum disorder (AQP4Ab+NMOSD) and healthy controls (HCs), as well as the impact of biologic agents (BIO) on brain atrophy, have not been fully examined. METHODS:In total, 72 patients with AQP4Ab+NMOSD identified at Chiba University Hospital or in the Berlin Registry of Neuroimmunological Entities (Chiba, 63; Berlin, 9) and 52 age-matched and sex-matched HCs (Chiba, 47; Berlin, 5) were included. Only patients without relapses between the baseline and follow-up MRI scans were included. Regional brain volumes were normalised to the intracranial volume. Patients who continuously used BIOs or non-BIO preventive treatments between the two MRI scans were assigned to the BIO or non-BIO subgroups, respectively. We applied a longitudinal combined association test to correct for MRI scanner differences. RESULTS:Patient age and the interval between MRI scans did not differ between the groups. The NMOSD group exhibited a lower whole-brain volume than the HC group at follow-up (p<0.001) and a significantly higher whole-brain atrophy rate (p=0.009). Patients with smaller subcortical grey matter (SGM) volumes at follow-up MRI exhibited greater clinical disability (ρ = -0.27, p=0.022). In the BIO subgroup, early initiation of treatment (p=0.013) and a higher relative duration of BIO exposure (p=0.028) were associated with lower annualised SGM atrophy rates. CONCLUSIONS:This study suggested progressive silent brain atrophy in patients with AQP4Ab+NMOSD and that early BIO initiation might prevent the progression of brain atrophy.

BACKGROUND:Chimeric antigen receptor (CAR) T cells targeting CD19 or B cell maturation antigen (BCMA) hold great promise to treat neuroimmune disorders, but the efficacy of CD19/BCMA dual-targeting CAR-T cells and their impact on systemic immunity are poorly understood. METHODS:In this phase 1 study (ClinicalTrials.gov: NCT06371040), patients with refractory generalized myasthenia gravis (gMG) received autologous CD19/BCMA CAR-T cells without prior lymphodepletion. The primary endpoint was the frequency and severity of treatment-emergent adverse events at week 4. Secondary endpoints included changes in MG-specific scale scores. Single-cell RNA sequencing and flow cytometry were performed to characterize longitudinal changes in B cell, plasma cell, and T cell compartments following CAR-T cell infusion. FINDINGS:CD19/BCMA CAR-T cells expanded in vivo, leading to depletion of B cells and plasma cells. All six patients had a favorable safety profile. Minimal symptom expression (MG Activities of Daily Living Score [MG-ADL] = 0) was achieved in five patients by day 90, with responses sustained through day 120-150, and all patients discontinued glucocorticoids while reducing immunosuppressant use. Immune profiling revealed a transient decline in memory B cells and plasma cells. The repopulated B cells exhibited attenuated B cell receptor signaling and increased inhibitory signals derived from bone marrow niche cells. Further, clonal expansion of T and B cells was significantly reduced. CONCLUSIONS:CD19/BCMA CAR-T cell therapy is safe and effective in refractory gMG without lymphodepletion, leading to systemic immune reset that warrants future investigations in larger clinical trials. FUNDING:This study was supported by the National Key Research and Development Program and the National Natural Science Foundation of China.

Neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are inflammatory disorders of the CNS with distinct immunopathologic mechanisms and treatment responses and partially overlapping clinical phenotypes. The identification of aquaporin-4 (AQP4)-IgG and MOG-IgG has transformed disease classification and diagnosis, enabled a classification of antibody-defined subgroups, and facilitated the development of targeted therapies. However, optimal use of these biomarkers in clinical practice requires careful interpretation within the appropriate clinical and radiologic context. This review synthesizes current evidence on established and emerging fluid biomarkers in NMOSD and MOGAD, with emphasis on analytical performance, biological relevance, and clinical utility. We review antibody detection using cell-based assays, highlighting differences between live and fixed platforms and the impact of antigen conformation on sensitivity and specificity, particularly for MOG-IgG. Common causes of false-positive and false-negative results are discussed, including low-titer reactivity, testing in low pretest probability populations, treatment-related antibody titer reduction, and assay-specific limitations. The diagnostic challenges posed by indiscriminate testing in adult cohorts with multiple sclerosis, in whom disease prevalence markedly exceeds that of MOGAD, are emphasized. We also discuss the role of repeat testing during acute attacks and paired serum-CSF analysis in improving diagnostic confidence when results are equivocal or discordant. Beyond disease-defining antibodies, we examine biomarkers of tissue injury and immune activation. Serum and CSF neurofilament light chain and glial fibrillary acidic protein provide complementary measures of neuroaxonal and astrocytic damage and show associations with attack severity, disease activity, relapse risk, and long-term disability. Cytokines, chemokines, and complement components reflect inflammatory pathways, including IL-6-driven immune activation in NMOSD and MOGAD and complement-mediated astrocytopathy in NMOSD, and may support mechanistic stratification and treatment monitoring in both conditions. We further review the contribution of CSF analysis, neuropathology, genetics, and antigen discovery platforms to refine disease classification, particularly in seronegative or atypical presentations. Finally, we outline priorities for future research, including assay harmonization, standardized sampling protocols, longitudinal biomarker profiling, and integrative multiomic approaches. Collectively, advances in biomarker science have the potential to improve diagnostic precision, guide individualized therapeutic strategies, and support de-escalation decisions in NMOSD and MOGAD.

BACKGROUND AND OBJECTIVES:Disability trajectories in aquaporin-4 immunoglobulin G-seropositive neuromyelitis optica spectrum disorder (AQP4-IgG+ NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are primarily driven by attack-related damage. Confirmed disability worsening (CDW) independent of attacks has been described but occurs infrequently in AQP4-IgG+ NMOSD and MOGAD. Confirmed disability improvement (CDI) has not been evaluated in large cohorts. We determined the frequency of CDI and CDW independent of attacks and identified clinical factors associated with these outcomes in AQP4-IgG+ NMOSD and MOGAD. METHODS:This retrospective, multicenter cohort study analyzed data from the German Neuromyelitis Optica Study Group (NEMOS) registry. Adult patients with AQP4-IgG+ NMOSD or MOGAD and longitudinal Expanded Disability Status Scale (EDSS) assessments were included. EDSS episodes were defined as periods with ≥3 EDSS assessments without attacks, obtained ≥90 days after attack. CDW and CDI were defined as sustained EDSS increase or decrease (≥1.5 for baseline EDSS 0; ≥1.0 for EDSS 1.0-5.5; ≥0.5 for EDSS ≥6.0) confirmed after at least 6 months. The primary outcomes were annualized CDI and CDW rates. Risk factors were assessed using multivariable Anderson-Gill regression models. RESULTS:A total of 338 EDSS episodes of 307 patients (n: 202/105, median age at EDSS change: 56/41 years, 88/49% female, both p < 0.001; AQP4-IgG+ NMOSD/MOGAD) were included. Adjusted annualized CDI and CDW rates did not differ between AQP4-IgG+ NMOSD (CDI: 0.083, 95% CI 0.029-0.233; CDW: 0.025, 95% CI 0.007-0.092) and MOGAD (CDI: 0.057, 95% CI 0.012-0.277; CDW: 0.036, 95% CI 0.002-0.513). In AQP4-IgG+ NMOSD, a lower number of prior attacks was associated with higher CDI rates (hazard ratio [HR] 0.89, 95% CI 0.82-0.97). Younger age was associated with increased CDI rates in both AQP4-IgG+ NMOSD and MOGAD (HR 0.96, 95% CI 0.94-0.99, for both). DISCUSSION:CDI and CDW independent of attacks, although rare, occur in AQP4-IgG+ NMOSD and MOGAD. The association between fewer prior attacks and higher CDI rates in AQP4-IgG+ NMOSD underscores the importance of early attack prevention. Limitations include the retrospective design, and the limited number of CDI and CDW events.

Background and ObjectivesNeuromyelitis optica spectrum disorder (NMOSD) is a severe autoimmune disease mainly driven by aquaporin-4 antibodies (AQP4-IgG). During an attack, AQP4-IgG activates the complement system, leading to astrocyte destruction, inflammation, neuronal damage, and thus devastating and often irreversible neurologic deficits. Terminal complement inhibitors such as eculizumab and ravulizumab effectively prevent relapses, yet their therapeutic potential in stopping ongoing complement-mediated injury during acute attacks remains insufficiently explored.MethodsWe conducted a multinational retrospective case series across NMOSD-specialized centers in 6 countries, analyzing 33 AQP4-IgG-positive patients (mean age: 48.1 years; 28 women) treated with component 5 (C5) inhibition during or shortly after acute relapse (mean 20.1 days from symptom onset; range 2-62). Eculizumab was used in 25 patients and ravulizumab in 8. Two additional patients were excluded because of delayed treatment initiation beyond 62 days.ResultsLesion locations included myelitis (57.6%) and optic neuritis (30.3%). Expanded Disability Status Scale scores worsened from a pre-relapse median of 0 (interquartile range [IQR] 0-2) to a nadir of 6.5 (IQR 3.5-8), improving to 3.5 (IQR 3-6.5) at 1-3 months and 2.5 (IQR 2-6) at 6 months. All patients stabilized clinically; 20 continued C5 inhibition as attack-preventing therapy. Good, moderate, and poor/absent recovery were observed in 15, 11, and 7 patients, respectively. Earlier treatment was associated with better outcomes: treatment within 21 days yielded an odds ratio of 1.58 (95% CI 0.32-8.52) for good response. Plasma exchange was administered in 57.6% and was associated with higher overall response rates, but not with good response alone.DiscussionThese findings highlight the potential of complement inhibition as a treatment option for acute NMOSD attacks, particularly in patients with insufficient response to standard therapies. Given the absence of clinical worsening and the encouraging course observed in most of the patients, further investigation into the role of C5 inhibition in acute attack management is warranted.Classification of EvidenceThis retrospective case series provides Class IV evidence that the C5 complement inhibitors eculizumab or ravulizumab may improve disability in patients with NMOSD when given during or shortly after acute relapse.

INTRODUCTION:Progression Independent of Relapse Activity (PIRA) is a critical measure of disability progression in multiple sclerosis (MS) independent of relapses but lacks a standardized definition. Current reliance on the Expanded Disability Status Scale (EDSS) limits sensitivity to non-motor domains, necessitating a stratified framework to enhance detection and guide management. OBJECTIVES:To develop a novel seven-level stratified PIRA definition and assess its validity, enhanced sensitivity, clinical relevance, and feasibility through expert consensus, and propose a simplified framework based on feedback. METHODS:A two-stage study: (1) A four-expert panel developed a seven-level PIRA framework (PIRA 1: EDSS-based; PIRA 2: EDSS-plus measures; PIRA 3: stress tests; PIRA 4: patient-reported outcomes [PROs]; PIRA 5: conventional MRI; PIRA 6: advanced MRI; PIRA 7: biomarkers) via literature synthesis. (2) A survey of 90 MS experts (26 responded, 28.9%) from nine countries evaluated each level's validity, sensitivity (vs. EDSS), relevance, and feasibility (1-5 scale), with open-ended comments on barriers and suggestions. High agreement was defined as a score ≥ 4. Qualitative feedback on barriers and improvement suggestions was thematically analyzed. RESULTS:Strong support (24/26; 92.3%) endorsed a stratified PIRA definition. Respondents included primarily clinician-researchers (22/26; 84.6%), with 11/26 (42.3%) reporting more than 20 years of MS experience. High agreement for validity ranged from 15/26 (57.7%) for PIRA 1-23/26 (88.5%) for PIRA 6. Agreement regarding enhanced sensitivity was highest for PIRA 2 (25/26; 96.2%), followed by PIRA 6 (22/26; 84.6%) and PIRA 5 (19/26; 73.1%). Clinical relevance was rated highly for PIRA 1, PIRA 2, and PIRA 6 (each 25/26; 96.2%). Feasibility was highest for PIRA 1 (24/26; 92.3%) and declined for higher levels, particularly PIRA 7. Barriers included inter-rater variability (PIRA 1, 30.8%), subjectivity (PIRA 4, 23.1%), and cost/expertise (PIRA 6-7, 26.9% each). Suggestions included digital tools (PIRA 2-3), AI for MRI (PIRA 5-6), biomarker validation (PIRA 7), and combining PIRA 5-6. PIRA 1-2 were preferred for clinical practice, PIRA 5-7 for research. A three-tier framework was proposed: Probable PIRA (clinical), Definite PIRA (clinical + MRI), and Definite PIRA Plus (clinical + MRI + biomarkers). CONCLUSIONS:The proposed seven-level PIRA framework demonstrates strong expert support for its conceptual validity and clinical relevance but highlights feasibility challenges for advanced assessments. A simplified three-tier model may provide a practical structure for standardized evaluation of relapse-independent progression in MS. Further empirical validation in diverse clinical cohorts is required.

ABSTRACT Purpose To demonstrate the synergy of undersampled radial 2in1‐RARE‐EPI acquisition and nonlinear model‐based reconstruction for accelerated and simultaneous T 2 , T 2 *, and R 2 ′ mapping in brains of patients with multiple sclerosis (MS). Methods 2in1‐RARE‐EPI combines a RARE module with an EPI module to capture T 2 and T 2 * information. Nonlinear model‐based reconstruction was applied to estimate T 2 , T 2 * maps directly from undersampled k ‐space data. A retrospective undersampling experiment was conducted to compare nonlinear model‐based and parallel imaging compressed sensing (PICS) reconstruction. The proposed approach was validated and compared to reference methods multiecho spin‐echo ( T 2 , MSE) and multiecho gradient‐echo ( T 2 *, MGRE) in a phantom, healthy subjects, and MS patients. Results 2in1‐RARE‐EPI together with nonlinear model‐based reconstruction enabled T 2 , T 2 *, and R 2 ′ mapping with 7.5‐fold scan‐time acceleration relative to the references, while addressing key limitations of reference techniques, including long acquisition times, misregistration, motion and off‐resonance sensitivity, and the need for calibration scans. Phantom and in vivo validation showed that the parametric maps obtained with this approach were in agreement with the reference methods. Compared with PICS, nonlinear model‐based reconstruction showed more consistent spatial detail and accuracy at higher acceleration factors. The proposed method detected small focal lesions in T 2 , T 2 *, and R 2 ′ maps of MS patients and enabled visualization of the central vein sign. Conclusion Scan time reduction facilitated by nonlinear model‐based reconstruction of 2in1‐RARE‐EPI provides a technical foundation for enhanced patient compliance, and is a fundamental precursor for broader clinical studies on the potential of T 2 , T 2 *, and R 2 ′ as imaging biomarkers.

When immune cells interact, they frequently exchange membrane-bound antigens. Our evolving understanding of these processes challenges the cellular specificity of lineage markers and therapeutic monoclonal antibodies. By using mouse and human B-T cell co-cultures, we report that CD19, an assumingly exclusive B cell marker, is transferred via trogocytosis when B cells activate T cells. In a B cell-driven model of experimental autoimmune encephalomyelitis, CD19+ T cells expand and show enhanced features of activation, differentiation, and encephalitogenic potential ex vivo. Additionally, co-transfer of CD19 and functional IgM from B cells results in the gain of B cell function by T cells. In patients with chronic central nervous system (CNS) demyelination, CD19+ T cells display a pro-inflammatory phenotype and are concomitantly depleted by inebilizumab, an approved anti-CD19 antibody, which raises important considerations for the therapeutic use of monoclonal antibodies overall. Finally, we report that myeloid cells acquire CD19 and functional IgM after phagocytosis of apoptotic B cells and thereby gain functional B cell properties. These findings highlight the commonness of membrane and antigen-transfer between cells, resulting in transmission of cellular function.

BACKGROUND AND OBJECTIVES:Neuromyelitis optica spectrum disorders (NMOSDs) comprise inflammatory processes of the CNS. Most patients with NMOSD have serum immunoglobulin (Ig) G autoantibodies directed against the astrocytic water channel aquaporin-4 (AQP4-IgG). In this study, we analyzed HLA allelic frequencies in a large cohort of patients with NMOSD, stratified by ethnicity and AQP4-IgG status, compared with healthy controls. METHODS:Next-generation sequencing-based HLA class I and II genotyping was performed in 174 White, 45 Black, and 41 Hispanic AQP4-IgG-positive (AQP4-IgG+) patients with NMOSD; 49 White patients with AQP4-IgG-negative (AQP4-IgG-) NMOSD; and 2,427 White, 244 Black, and 155 Hispanic controls. Correction for multiple testing was performed using the Bonferroni method. RESULTS:In White AQP4-IgG+ patients with NMOSD, the most significantly associated alleles were HLA-DQA1*05:01:01 (30.1% vs 11.1%, odds ratio 3.43 [95% CI 2.65-4.42], corrected p = 8.95E-17), HLA-DQB1*02:01:01 (29.9% vs 11.3%, 3.34 [2.58-4.31], corrected p = 4.33E-16), and HLA-DRB1*03:01:01 (29.2% vs 11.6%, 3.15 [2.43-4.06], corrected p = 3.66E-14), followed by HLA-B*08:01:01 (26% vs 10.4%, 3.02 [2.3-3.94] corrected p = 8.79E-12), HLA-C*07:01:01 (27.8% vs 14%, 2.36 [1.81-3.04], corrected p = 2.44E-07), and HLA-DRB3*01:01:02 (28% vs 14.7%, 2.27 [1.73-2.95], corrected p = 2.19E-06). The frequency of HLA-DRB1*08:04:01 was higher in Black AQP4-IgG+ patients with NMOSD than in Black controls but did not achieve statistical significance (19.3% vs 5.7%, 3.92 [1.91-7.86], corrected p = 0.08). Nevertheless, when compared with a larger cohort of Black controls (n = 16,178), the frequency of HLA-DRB1*08:04 (19.3% vs 5.1%, 4.46 [2.45-7.66], corrected p = 1.88E-03) was significantly higher in Black AQP4-IgG+ patients with NMOSD. No significant HLA associations were detected in AQP4-IgG+ Hispanic patients or White AQP4-IgG- patients with NMOSD. DISCUSSION:This study confirms the previously recognized association of HLA-DRB1*03:01 with AQP4-IgG+ NMOSD in White patients and extends this association to the HLA-DRB1*03:01:01∼HLA-DQA1*05:01:01∼HLA-DQB1*02:01:01 haplotype. Furthermore, it identifies an association of HLA-DRB1*08:04 with AQP4-IgG+ NMOSD in Black patients. However, no HLA associations were detected in White AQP4-IgG- patients with NMOSD. The immunogenetic differences between AQP4-IgG+ and AQP4-IgG- NMOSD support pathophysiologic distinctions between these entities.

Bone marrow hematopoietic stem and progenitor cells (HSPCs) sense immune activation and instruct systemic immunity. However, the alterations of HSPCs in autoimmune diseases, which are driven by an active immune response, and their impact on disease activity and progression are not clear. Neuromyelitis optica spectrum disorder (NMOSD) is a B cell-mediated autoimmune neurological disease characterized by pathogenic autoantibodies against aquaporin-4 (AQP4-IgG). We observed aberrant bone marrow granulopoiesis in samples from individuals with NMOSD, which was accompanied by B cell clonal expansion. Aberrant granulopoiesis was mediated by hyperactivated JAK-STAT signaling, leading to an increase in ISG15+ neutrophils that produced B cell-activating factor (BAFF). These BAFF-producing neutrophils were sufficient to drive maturation of antibody-secreting cells and autoantibody production in vitro. Aberrant granulopoiesis was also observed in individuals with NMOSD receiving B cell depletion therapy who experienced relapse; in contrast, belimumab, a monoclonal antibody against BAFF, reduced autoantibody titers and number of relapses. Thus, targeting the bone marrow niche may present a treatment strategy for NMOSD and perhaps other B cell-mediated autoimmune diseases.

Abstract Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease of the central nervous system characterized by loss of immune tolerance to the water channel aquaporin-4 (AQP4). Current therapies do not specifically restore AQP4 tolerance or selectively suppress antigen-specific immune responses. Reprogramming patient’s own dendritic cells (DCs) with mRNA to induce tolerance represents a promising therapeutic strategy. A key prerequisite for this approach is generating mRNAs encoding disease-relevant autoantigens recognized by the patient’s immune system. Here, we generated recombinant mRNAs encoding human AQP4 and evaluated T cell responses to autologous DCs transfected with AQP4 mRNA in eight NMOSD patients and ten healthy controls. Transfected DCs were co-cultured with autologous T cells and stimulated twice. The assay detected robust AQP4-specific T cell response in a patient with recent disease activity who was not receiving immunosuppressive therapy, demonstrating its ability to identify clinically relevant autoreactive T cell responses. These findings establish the feasibility of an mRNA-based antigen-specific T cell assay for studying NMOSD pathogenesis, stratifying patients by T cell involvement, and supporting development of personalized tolerance-inducing therapies. Summary Sentence Recombinant mRNA encoding human aquaporin-4 (AQP4) was introduced into dendritic cells from NMOSD patients, enabling the detection of antigen-specific T cell responses, with the strongest activation observed in a patient with recent disease activity, highlighting the potential of this approach for immune monitoring and for understanding the role of T cells in the pathogenesis of NMOSD.

BACKGROUND:Neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are rare autoimmune disorders of the central nervous system whose diagnosis increasingly relies on highly sensitive antibody assays and timely access to targeted therapies. Despite major advances in the diagnosis and management of these disorders worldwide, substantial challenges continue to compromise patient care across Latin America (LATAM). METHODS:This consensus-informed regional perspective was developed as an initiative of the European Charcot Foundation (ECF) Young Investigators/Fellows, following discussions held during the "2025 Update on NMOSD & MOGAD" ECF Meeting in São Paulo/Brazil, and in collaboration with international and Latin American experts. This manuscript synthesizes current evidence on the epidemiology, clinical characteristics, diagnosis, treatment, and healthcare challenges of NMOSD and MOGAD in LATAM, together with a consensus-informed assessment of regional priorities and unmet needs. KEY FINDINGS:Recent epidemiological studies have improved understanding of the burden of NMOSD and MOGAD across LATAM. Nevertheless, delayed diagnosis, disease misclassification, unequal access to specialized neuroimmunology services, and considerable variability in antibody testing methodologies remain major barriers to optimal patient management. Although commercial fixed cell-based assays (fixed-CBAs) have become increasingly available throughout the region, access to gold-standard live cell-based assays (live-CBAs) remains restricted to a limited number of specialized centers, potentially compromising diagnostic accuracy in some settings. Likewise, despite growing evidence supporting early initiation of highly effective therapies, particularly for AQP4-IgG-positive NMOSD, access to these treatments is limited in many locations, resulting in continued reliance on conventional immunosuppressive agents. CONCLUSIONS:Based on the available evidence and expert consensus, this regional perspective identifies two strategic priorities for advancing the diagnosis and management of NMOSD and MOGAD in LATAM: (I) expanding access to locally performed live-CBA and (II) ensuring equitable access to highly effective emerging therapies. Together, these priorities have the potential to harmonize clinical practice and reduce healthcare disparities across countries. They may also foster regional neuroimmunology collaborations, facilitating the generation of reliable region-specific real-world evidence, ultimately benefiting patients with NMOSD and MOGAD throughout LATAM.

BACKGROUND AND OBJECTIVES:Neuromyelitis optica spectrum disorder (NMOSD) is a severe autoimmune disease mainly driven by aquaporin-4 antibodies (AQP4-IgG). During an attack, AQP4-IgG activates the complement system, leading to astrocyte destruction, inflammation, neuronal damage, and thus devastating and often irreversible neurologic deficits. Terminal complement inhibitors such as eculizumab and ravulizumab effectively prevent relapses, yet their therapeutic potential in stopping ongoing complement-mediated injury during acute attacks remains insufficiently explored. METHODS:We conducted a multinational retrospective case series across NMOSD-specialized centers in 6 countries, analyzing 33 AQP4-IgG-positive patients (mean age: 48.1 years; 28 women) treated with component 5 (C5) inhibition during or shortly after acute relapse (mean 20.1 days from symptom onset; range 2-62). Eculizumab was used in 25 patients and ravulizumab in 8. Two additional patients were excluded because of delayed treatment initiation beyond 62 days. RESULTS:Lesion locations included myelitis (57.6%) and optic neuritis (30.3%). Expanded Disability Status Scale scores worsened from a pre-relapse median of 0 (interquartile range [IQR] 0-2) to a nadir of 6.5 (IQR 3.5-8), improving to 3.5 (IQR 3-6.5) at 1-3 months and 2.5 (IQR 2-6) at 6 months. All patients stabilized clinically; 20 continued C5 inhibition as attack-preventing therapy. Good, moderate, and poor/absent recovery were observed in 15, 11, and 7 patients, respectively. Earlier treatment was associated with better outcomes: treatment within 21 days yielded an odds ratio of 1.58 (95% CI 0.32-8.52) for good response. Plasma exchange was administered in 57.6% and was associated with higher overall response rates, but not with good response alone. DISCUSSION:These findings highlight the potential of complement inhibition as a treatment option for acute NMOSD attacks, particularly in patients with insufficient response to standard therapies. Given the absence of clinical worsening and the encouraging course observed in most of the patients, further investigation into the role of C5 inhibition in acute attack management is warranted. CLASSIFICATION OF EVIDENCE:This retrospective case series provides Class IV evidence that the C5 complement inhibitors eculizumab or ravulizumab may improve disability in patients with NMOSD when given during or shortly after acute relapse.

The 2024 revised McDonald criteria for multiple sclerosis recognize the optic nerve as a topography for dissemination in space. Optical coherence tomography-derived inter-eye differences in peri-papillary retinal nerve fiber layer or ganglion cell-inner plexiform layer thicknesses (≥6μm or ≥4μm, respectively) are proposed for identifying unilateral optic nerve involvement. However, the value of combining inter-eye difference measures and optimal temporal-quadrant peri-papillary retinal nerve fiber layer inter-eye differences remains unclear. We investigated the diagnostic performance of combined inter-eye differences, optimal temporal-quadrant peri-papillary retinal nerve fiber layer inter-eye differences, and examined the effects of time, prior optic neuritis frequency, sex, and race on inter-eye differences. Retinal optical coherence tomography images from all study participants underwent rigorous quality control. Receiver operating characteristic analyses and area under the receiver operating characteristic curves (AUC) were used to determine optimal inter-eye differences of individual and combined measures to distinguish eyes with, from without, prior optic neuritis in people with multiple sclerosis. Mixed-effects models were used to assess impact of time, prior optic neuritis events, sex, and race on inter-eye differences. An independent multiple sclerosis cohort from a second center was examined for external validation. Among 1854 people with multiple sclerosis, optimal inter-eye difference thresholds for identifying unilateral optic nerve involvement were 6μm for peri-papillary retinal nerve fiber layer (AUC=0.80), 4μm for ganglion cell-inner plexiform layer (AUC=0.83), and 8μm for temporal-quadrant peri-papillary retinal nerve fiber layer (AUC=0.71) thicknesses. Peri-papillary retinal nerve fiber layer inter-eye differences ≥6μm or ganglion cell-inner plexiform layer inter-eye differences ≥4μm yielded 87.6% sensitivity, 70.0% specificity, and 64.0% positive predictive value. Concurrent inter-eye differences at lower thresholds (≥5μm peri-papillary retinal nerve fiber layer, ≥3μm ganglion cell-inner plexiform layer) reduced sensitivity to 72.5%, but improved specificity (86.6%) and positive predictive value (76.7%), while maintaining accuracy and negative predictive value. Temporal-quadrant peri-papillary retinal nerve fiber layer inter-eye differences did not improve diagnostic performance. Over a median of 5.1 years, ganglion cell-inner plexiform layer and peri-papillary retinal nerve fiber layer inter-eye differences remained stable. Prior optic neuritis counts and sex did not affect inter-eye differences. Although Black Americans had higher inter-eye differences than White Americans, optimal thresholds were comparable across races. The validation cohort comprising 254 people with multiple sclerosis confirmed these findings. In conclusion, concurrent peri-papillary retinal nerve fiber layer (≥5μm) and ganglion cell-inner plexiform layer inter-eye differences (≥3μm) improve unilateral optic nerve involvement detection versus either alone (≥6μm or ≥4μm, respectively), while temporal-quadrant peri-papillary retinal nerve fiber layer inter-eye differences offer limited benefit. Inter-eye differences remain stable longitudinally and unaffected by prior optic neuritis frequency.

BACKGROUND AND OBJECTIVES:Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an inflammatory demyelinating disorder that overlaps clinically with multiple sclerosis (MS) but immunopathologically distinct. Although often considered an acute inflammatory disease, recurrent attacks in MOGAD can lead to demyelination, axonal injury, and secondary neurodegeneration. Reliable biomarkers associated with relapse risk and disease subphenotypes, including optic neuritis, remain limited. Here, we aimed to define molecular and cellular signatures that distinguish MOGAD from MS as a prototypical neuroinflammatory disease and from Alzheimer disease (AD) as a proxy of neurodegeneration and to identify candidate immune-proteomic features associated with relapse frequency and clinical phenotype in MOGAD. METHODS:CSF, serum, and whole-blood samples from patients with MOGAD (n = 67), MS (n = 49), and AD (n = 36) were profiled using NULISAseq™ CSF proteomics, Olink Explore 3072 CSF and serum proteomics, and high-dimensional mass cytometry for immune cell characterization. In MOGAD, longitudinal clinical data, including total attack counts from the earliest documented attack through follow-up, were integrated with immune and proteomic profiles to assess associations with disease course and clinical phenotype. RESULTS:CSF and blood proteomic profiling revealed distinct inflammatory and cardiometabolic proteomic profiles in MOGAD, differentiating it from both MS and AD. Compared with MS, MOGAD showed relative reductions in lymphocyte populations with regulatory phenotypes. Within MOGAD, relapsing disease was associated with reduced frequencies of CD8+CCR7+CD31+CTLA4+ T cells and concurrent expansion of double-negative γδ T-cell subsets. IL-13 correlated positively with relapse frequency and inversely with circulating regulatory T cells, whereas IL-32 and CASP4 showed opposite associations, correlating negatively with relapse count and positively with Treg frequency. IL-13 was also inversely associated with CD31-expressing CD8+ T cells. Phenotype-stratified analyses suggested that these immune-proteomic relationships differed according to clinical presentation, including optic neuritis vs nonoptic neuritis phenotypes. DISCUSSION:This integrative immune-proteomic analysis identifies cellular and molecular features associated with relapsing vs monophasic MOGAD, suggesting a model of impaired peripheral immune regulation in relapsing disease. While exploratory, these findings generate a concrete hypothesis for future longitudinal and functional studies aimed at refining biomarker-based monitoring and informing individualized therapeutic strategies in MOGAD.