The Potential Pathogenicity of Myelin Oligodendrocyte Glycoprotein Antibodies in the Optic Pathway

The real-world applicability of the 2023 international myelin oligodendrocyte glycoprotein antibody-associated disease criteria in a Latin American cohort

BACKGROUND AND PURPOSE

The diagnostic criteria for myelin oligodendrocyte glycoprotein antibody (MOG-IgG)-associated disease (MOGAD) were published in 2023. We aimed to determine the performance of the new criteria in Latin American (LATAM) patients compared with the 2018 criteria and explore the significance of MOG-IgG titers in diagnosis.

METHODS

We retrospectively reviewed the medical records of LATAM (Argentina, Chile, Brazil, Peru, Ecuador, and Colombia) adult patients with one clinical MOGAD event and MOG-IgG positivity confirmed by cell-based assay. Both 2018 and 2023 MOGAD criteria were applied, calculating diagnostic performance indicators.

RESULTS

Among 171 patients (predominantly females, mean age at first attack = 34.1 years, mean disease duration = 4.5 years), 98.2% patients met the 2018 criteria, and of those who did not fulfill diagnostic criteria (n = 3), all tested positive for MOG-IgG (one low-positive and two without reported titer). Additionally, 144 (84.2%) patients met the 2023 criteria, of whom 57 (39.5%) had MOG-IgG+ titer information (19 clearly positive and 38 low-positive), whereas 87 (60.5%) patients had no MOG-IgG titer. All 144 patients met diagnostic supporting criteria. The remaining 27 patients did not meet the 2023 MOGAD criteria due to low MOG-IgG (n = 12) or lack of titer antibody access (n = 15), associated with the absence of supporting criteria. The 2023 MOGAD criteria showed a sensitivity of 86% (95% confidence interval = 0.80-0.91) and specificity of 100% compared to the 2018 criteria.

CONCLUSIONS

These findings support the diagnostic utility of the 2023 MOGAD criteria in an LATAM cohort in real-world practice, despite limited access to MOG-IgG titration.

Immune System Dysregulation in the Progression of Multiple Sclerosis: Molecular Insights and Therapeutic Implications

Multiple sclerosis (MS), a prevalent neurological disorder, predominantly affects young adults and is characterized by chronic autoimmune activity. The study explores the immune system dysregulation in MS, highlighting the crucial roles of immune and non-neuronal cells in the disease's progression. This review examines the dual role of cytokines, with some like IL-6, TNF-α, and interferon-gamma (IFN-γ) promoting inflammation and CNS tissue injury, and others such as IL-4, IL-10, IL-37, and TGF-β fostering remyelination and protecting against MS. Elevated chemokine levels in the cerebrospinal fluid (CSF), including CCL2, CCL5, CXCL10, CXCL13, and fractalkine, are analyzed for their role in facilitating immune cell migration across the blood-brain barrier (BBB), worsening inflammation and neurodegeneration. The study also delves into the impact of auto-antibodies targeting myelin components like MOG and AQP4, which activate complement cascades leading to further myelin destruction. The article discusses how compromised BBB integrity allows immune cells and inflammatory mediators to infiltrate the CNS, intensifying MS symptoms. It also examines the involvement of astrocytes, microglia, and oligodendrocytes in the disease's progression. Additionally, the effectiveness of immunomodulatory drugs such as IFN-β and CD20-targeting monoclonal antibodies (e.g., rituximab) in modulating immune responses is reviewed, highlighting their potential to reduce relapse rates and delaying MS progression. These insights emphasize the importance of immune system dysfunction in MS development and progression, guiding the development of new therapeutic strategies. The study underscores recent advancements in understanding MS's molecular pathways, opening avenues for more targeted and effective treatments.

Body fluid markers for multiple sclerosis and differential diagnosis from atypical demyelinating disorders

INTRODUCTION

Body fluid markers could be helpful to predict the conversion into clinically definite multiple sclerosis (MS) in people with a first demyelinating event of the central nervous system (CNS). Consequently, biomarkers such as oligoclonal bands, which are integrated in the current MS diagnostic criteria, could assist early MS diagnosis.

AREAS COVERED

This review examines existing knowledge on a broad spectrum of body fluid markers in people with a first CNS demyelinating event, explores their potential to predict conversion to MS, to assess MS disease activity, as well as their utility to differentiate MS from atypical demyelinating disorders such as neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein associated disease.

EXPERT OPINION

This field of research has shown a dramatic increase of evidence, especially in the last decade. Some biomarkers are already established in clinical routine (e.g. oligoclonal bands) while others are currently implemented (e.g. kappa free light chains) or considered as breakthroughs (e.g. neurofilament light). Determination of biomarkers poses challenges for continuous monitoring, especially if exclusively detectable in cerebrospinal fluid. A handful of biomarkers are measurable in blood which holds a significant potential.

Comparison of glial fibrillary acidic protein-immunoglobulin G-associated myelitis with myelin oligodendrocyte glycoprotein-immunoglobulin G-associated myelitis

Objective

Glial fibrillary acidic protein-immunoglobulin G (GFAP-IgG)-associated myelitis and myelin oligodendrocyte glycoprotein-IgG (MOG-IgG)-associated myelitis have rarely been compared. Therefore, this study aimed to explore the clinical, laboratory, and imaging features of them to identify the differences.

Methods

Overall, 14 and 24 patients with GFAP-IgG-and MOG-IgG-associated myelitis, respectively, were retrospectively screened and included in the study.

Results

Among the 14 patients with GFAP-IgG-associated myelitis, the condition was more common in males (71.4%), with a median age of onset of 36.5 years, and more common in adults than in children (35.7%). In contrast, among the 24 patients with MOG-IgG-associated myelitis, the condition was equally divided between males and females, with a median age of onset of 9.5 years and more in children (66.7%) than in adults. The median age of onset of GFAP-IgG-associated myelitis was later than that of the MOG-IgG group. Isolated myelitis was rare in both groups. Elevated cerebrospinal fluid (CSF) protein levels were more prevalent in patients with GFAP-IgG-associated myelitis (64.3%) than in those with MOG-IgG-associated myelitis (16.7%) (p < 0.05), whereas patchy gadolinium enhancement of the cerebral lesion site was less common in patients with GFAP-IgG-associated myelitis than in those with MOG-IgG associated myelitis (p < 0.05). Six patients had a combination of other neurological autoantibodies, the specific mechanism of the overlapping antibodies remains unclear.

Conclusion

Cerebrospinal fluid analysis and gadolinium enhanced MRI examination may help to distinguish the two kinds of myelitis.

Pathogenesis, Clinical Features, and Treatment of Patients with Myelin Oligodendrocyte Glycoprotein (MOG) Autoantibody-Associated Disorders Focusing on Optic Neuritis with Consideration of Autoantibody-Binding Sites: A Review

Although there is a substantial amount of data on the clinical characteristics, diagnostic criteria, and pathogenesis of myelin oligodendrocyte glycoprotein (MOG) autoantibody-associated disease (MOGAD), there is still uncertainty regarding the MOG protein function and the pathogenicity of anti-MOG autoantibodies in this disease. It is important to note that the disease characteristics, immunopathology, and treatment response of MOGAD patients differ from those of anti-aquaporin 4 antibody-positive neuromyelitis optica spectrum disorders (NMOSDs) and multiple sclerosis (MS). The clinical phenotypes of MOGAD are varied and can include acute disseminated encephalomyelitis, transverse myelitis, cerebral cortical encephalitis, brainstem or cerebellar symptoms, and optic neuritis. The frequency of optic neuritis suggests that the optic nerve is the most vulnerable lesion in MOGAD. During the acute stage, the optic nerve shows significant swelling with severe visual symptoms, and an MRI of the optic nerve and brain lesion tends to show an edematous appearance. These features can be alleviated with early extensive immune therapy, which may suggest that the initial attack of anti-MOG autoantibodies could target the structures on the blood-brain barrier or vessel membrane before reaching MOG protein on myelin or oligodendrocytes. To understand the pathogenesis of MOGAD, proper animal models are crucial. However, anti-MOG autoantibodies isolated from patients with MOGAD do not recognize mouse MOG efficiently. Several studies have identified two MOG epitopes that exhibit strong affinity with human anti-MOG autoantibodies, particularly those isolated from patients with the optic neuritis phenotype. Nonetheless, the relations between epitopes on MOG protein remain unclear and need to be identified in the future.

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD): current understanding and challenges

New diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) have recently been proposed, distinguishing this syndrome from other inflammatory diseases of the central nervous system. Seropositivity status for MOG-IgG autoantibodies is important for diagnosing MOGAD, but only in the context of robust clinical characterization and cautious interpretation of neuroimaging. Over the last several years, access to cell-based assay (CBA) techniques has improved diagnostic accuracy, yet the positive predictive value of serum MOG-IgG values varies with the prevalence of MOGAD in any given patient population. For this reason, possible alternative diagnoses need to be considered, and low MOG-IgG titers need to be carefully weighted. In this review, cardinal clinical features of MOGAD are discussed. Key challenges to the current understanding of MOGAD are also highlighted, including uncertainty regarding the specificity and pathogenicity of MOG autoantibodies, the need to identify immunopathologic targets for future therapies, the quest to validate biomarkers that facilitate diagnosis and detect disease activity, and the importance of deciphering which patients with MOGAD require long-term immunotherapy.