The changing landscape of optic neuritis: a narrative review

A Comparative Review of Typical and Atypical Optic Neuritis: Advancements in Treatments, Diagnostics, and Prognosis

Optic neuritis (ON) is a debilitating condition that through various mechanisms, including inflammation or demyelination of the optic nerve, can result in partial or total permanent vision loss if left untreated. Accurate diagnosis and promptly initiated treatment are imperative related to the potential of permanent loss of vision if left untreated, which can lead to a significant reduction in the quality of life in affected patients. ON is subtyped as "typical" or "atypical" based on underlying causative etiology. The etiology of ON can be differentiated when appropriate diagnostic testing is performed. Using history taking, neuroimaging, and visual testing to localize the underlying pathology of ON in a time-sensitive manner is critical in mitigating these unsatisfactory outcomes. Herein, we examine the differences in presentation, pathophysiology, and treatments of typical ON causes, like multiple sclerosis (MS), and atypical causes such as neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein (MOG)-immunoglobulin G (IgG) ON. The present investigation places focus on both neuroimaging and visual imaging in the differentiation of ON. Additionally, this review presents physicians with a better understanding of different presentations, treatments, and prognoses of ON.

Myelin oligodendrocyte glycoprotein antibody-associated disease with clinical presentation as multiple episodes of isolated meningeal involvement: a case report

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) constitutes a group of autoimmune neuroinflammatory conditions that are characterized by positive serum MOG-immunoglobulin G antibodies. The relationship between MOGAD and immune factors remains unclear. Herein, we report a man in his early 30s who initially presented symptoms of headache and low-grade fever persisting for 20 days. The patient experienced isolated meningitis onset and had recurrent meningitis as the primary clinical feature, which manifested as low-grade fever, headache, and neck rigidity. Although cranial magnetic resonance imaging showed no abnormalities, immunotherapy was promptly administered upon diagnosing MOGAD through positive MOG-specific antibody testing of cerebrospinal and serum fluids. Notably, the patient's symptoms exhibited rapid improvement following treatment. Although meningitis is traditionally associated with infectious diseases, it can also occur in antibody-related autoimmune diseases that affect the central nervous system. Consequently, MOGAD should be considered in cases of aseptic meningitis with an unknown etiology, to facilitate definitive diagnosis and enhance patient prognosis.

Smart Nanoscale Extracellular Vesicles in the Brain: Unveiling their Biology, Diagnostic Potential, and Therapeutic Applications

Information exchange is essential for the brain, where it communicates the physiological and pathological signals to the periphery and vice versa. Extracellular vesicles (EVs) are a heterogeneous group of membrane-bound cellular informants actively transferring informative calls to and from the brain via lipids, proteins, and nucleic acid cargos. In recent years, EVs have also been widely used to understand brain function, given their "cell-like" properties. On the one hand, the presence of neuron and astrocyte-derived EVs in biological fluids have been exploited as biomarkers to understand the mechanisms and progression of multiple neurological disorders; on the other, EVs have been used in designing targeted therapies due to their potential to cross the blood-brain-barrier (BBB). Despite the expanding literature on EVs in the context of central nervous system (CNS) physiology and related disorders, a comprehensive compilation of the existing knowledge still needs to be made available. In the current review, we provide a detailed insight into the multifaceted role of brain-derived extracellular vesicles (BDEVs) in the intricate regulation of brain physiology. Our focus extends to the significance of these EVs in a spectrum of disorders, including brain tumors, neurodegenerative conditions, neuropsychiatric diseases, autoimmune disorders, and others. Throughout the review, parallels are drawn for using EVs as biomarkers for various disorders, evaluating their utility in early detection and monitoring. Additionally, we discuss the promising prospects of utilizing EVs in targeted therapy while acknowledging the existing limitations and challenges associated with their applications in clinical scenarios. A foundational comprehension of the current state-of-the-art in EV research is essential for informing the design of future studies.

Predictors of Long-Term Visual Acuity in a Modern Cohort of Patients With Acute Idiopathic and Multiple Sclerosis-Associated Optic Neuritis

BACKGROUND

For patients with idiopathic or multiple sclerosis (MS)-associated optic neuritis (ON), the largest multicenter clinical trial (Optic Neuritis Treatment Trial [ONTT]) showed excellent visual outcomes and baseline high-contrast visual acuity (HCVA) was the only predictor of HCVA at 1 year. We aimed to evaluate predictors of long-term HCVA in a modern, real-world population of patients with ON and compare with previously published ONTT models.

METHODS

We performed a retrospective, longitudinal, observational study at the University of Michigan and the University of Calgary evaluating 135 episodes of idiopathic or MS-associated ON in 118 patients diagnosed by a neuro-ophthalmologist within 30 days of onset (January 2011-June 2021). Primary outcome measured was HCVA (Snellen equivalents) at 6-18 months. Multiple linear regression models of 107 episodes from 93 patients assessed the association between HCVA at 6-18 months and age, sex, race, pain, optic disc swelling, symptoms (days), viral illness prodrome, MS status, high-dose glucocorticoid treatment, and baseline HCVA.

RESULTS

Of the 135 acute episodes (109 Michigan and 26 Calgary), median age at presentation was 39 years (interquartile range [IQR], 31-49 years), 91 (67.4%) were women, 112 (83.0%) were non-Hispanic Caucasians, 101 (75.9%) had pain, 33 (24.4%) had disc edema, 8 (5.9%) had a viral prodrome, 66 (48.9%) had MS, and 62 (46.6%) were treated with glucocorticoids. The median (IQR) time between symptom onset and diagnosis was 6 days (range, 4-11 days). The median (IQR) HCVA at baseline and at 6-18 months were 20/50 (20/22, 20/200) and 20/20 (20/20, 20/27), respectively; 62 (45.9%) had better than 20/40 at baseline and 117 (86.7%) had better than 20/40 at 6-18 months. In linear regression models (n = 107 episodes in 93 patients with baseline HCVA better than CF), only baseline HCVA (β = 0.076; P = 0.027) was associated with long-term HCVA. Regression coefficients were similar and within the 95% confidence interval of coefficients from published ONTT models.

CONCLUSIONS

In a modern cohort of patients with idiopathic or MS-associated ON with baseline HCVA better than CF, long-term outcomes were good, and the only predictor was baseline HCVA. These findings were similar to prior analyses of ONTT data, and as a result, these are validated for use in conveying prognostic information about long-term HCVA outcomes.

Can volumetric analysis of the brain help diagnose isolated optic neuritis?

Isolated optic neuritis is a single episode inflammatory optic neuropathy. This condition, which affects the optimal function of the optic nerve, is not associated with neurological or systemic diseases. Our study aimed to compare patients with isolated optic neuritis and normal healthy individuals in terms of the cerebrum, cerebellum and hippocampus volumes by using the "volBrain Online MRI Brain Volumetry System" program. Persons diagnosed with isolated optic neuritis (n = 16) and persons without any disease (n = 16) were included in the study. VolBrain was used to process the MRI data and, the findings were compared with Mann-Whitney U test. Values with a p-value <0.05 were considered statistically significant. The cerebrum white matter volumes in the total brain and in the right-left hemispheres of the brain were statistically significantly lower in the optic neuritis group (p = 0.029; p = 0.050; p = 0.029, respectively). In the segmental cerebellum analysis, the left side lobule VIIIB, the total and right-left side lobule IX volumes were statistically significantly higher (p = 0.022; p = 0.014; p = 0.029; p = 0.018, respectively). In total, lobule I-II volume was statistically significantly lower in the optic neuritis group (p = 0.046). In the segmental hippocampus analysis, the right side CA2-CA3, the total and right-left side SR-SL-SM volumes were statistically significantly lower in the optic neuritis group (p = 0.039; p = 0.050; p = 0.016, respectively). There are neurodegenerative changes in brain volume in patients with isolated optic neuritis. Although volBrain alone is not sufficient to diagnose isolated optic neuritis, it provides quantitative data that can be used as a complementary diagnostic method.

Bilateral retinal nerve fiber layer thickness reduction in a 9-year-old myopic boy suffering from unilateral optic neuritis: A case report

BACKGROUND

In this paper, we present a 9-year-old boy who demonstrates a complex interplay between myopia progression, axial length (AL) extension, and retinal nerve fiber layer (RNFL) thickness loss in both eyes. Additionally, concurrent optic neuritis has directly impacted RNFL thickness in his right eye, and its potential indirect influence on RNFL and macular ganglion cell layer (mGCL) thickness in his left eye is also noteworthy.

CASE SUMMARY

A 9-year-old boy with bilateral myopia presented with diminished vision and pain in his right eye due to optic neuritis, while his left eye showed pseudopapilledema. Steroid therapy improved his vision in the right eye, and 16-mo follow-up revealed recovery without recurrence despite myopia progression. Follow-up optical coherence tomography conducted 16 mo later revealed a notable thinning of the RNFL in both eyes, especially along with a reduction in mGCL thickness in the left eye. This intricate interaction between optic neuritis, myopia, and retinal changes underscores the need for comprehensive management, highlighting potential long-term visual implications in young patients.

CONCLUSION

The progression of myopia and AL extension led to the loss of RNFL thickness in both eyes in a 9-year-old boy. Concurrently, optic neuritis directly affected RNFL thickness in his right eye and may indirectly play a role in the thickness of RNFL and mGCL in his left eye.

An update on optic neuritis

Optic neuritis (ON) is the most common cause of subacute optic neuropathy in young adults. Although most cases of optic neuritis (ON) are classified as typical, meaning idiopathic or associated with multiple sclerosis, there is a growing understanding of atypical forms of optic neuritis such as antibody mediated aquaporin-4 (AQP4)-IgG neuromyelitis optica spectrum disorder (NMOSD) and the recently described entity, myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD). Differentiating typical ON from atypical ON is important because they have different prognoses and treatments. Findings of atypical ON, including severe vision loss with poor recovery with steroids or steroid dependence, prominent optic disc edema, bilateral vision loss, and childhood or late adult onset, should prompt serologic testing for AQP4-IgG and MOG-IgG. Although the traditional division of typical and atypical ON can be helpful, it should be noted that there can be severe presentations of otherwise typical ON and mild presentations of atypical ON that blur these traditional lines. Rare causes of autoimmune optic neuropathies, such as glial fibrillary acidic protein (GFAP) and collapsin response-mediator protein 5 (CRMP5) autoimmunity also should be considered in patients with bilateral painless optic neuropathy associated with optic disc edema, especially if there are other accompanying suggestive neurologic symptoms/signs. Typical ON usually recovers well without treatment, though recovery may be expedited by steroids. Atypical ON is usually treated with intravenous steroids, and some forms, such as NMOSD, often require plasma exchange for acute attacks and long-term immunosuppressive therapy to prevent relapses. Since treatment is tailored to the cause of the ON, elucidating the etiology of the ON is of the utmost importance.

The 100 Most-Cited Articles on Optic Neuritis: Trends of Subtypes, Authorship, and Time

BACKGROUND

Optic neuritis (ON) is an optic nerve inflammation that may lead to different degrees of vision loss. In recent decades, ON research facilitated a better understanding of the disease and its subtypes. This bibliometric analysis aimed to detect the 100 most-cited medical articles related to ON in the last 50 years (1972-2021) and describe publication trends arising from the list.

METHODS

The Scopus database was used to locate and screen the 100 most influential ON papers based on the number of citations per article. Each entry was reviewed for the first author (name, gender, institution, and country), year of publication, journal, number of citations, ON subtype, and study design. The mean impact factor (IF) of each journal was calculated.

RESULTS

The median number of citations was 265 (range 182-2,396). Observational studies on neuromyelitis optica-associated ON were the most common (27%), and the most influential decade was 2002-2011 (54 papers). Seventy-nine percent of articles were published in neurology journals, and a positive correlation between the mean number of citations per article and the journal mean IF was observed ( r = 0.62, P < 0.001). Between 2009 and 2021, female authors led more ON studies (52%), and more publications originated outside the USA (68%), compared with previous years.

CONCLUSIONS

This analysis summarizes the impact and shifting trends of ON research in the last decades.

The Treatment of Acute Optic Neuritis

Despite the high incidence of optic neuritis (ON), and the growing number of therapeutic options for the long-term treatment of diseases associated with ON including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) and MOG antibody associated disease (MOGAD), there are still only limited therapeutic options for treating an acute event of optic neuritis. These include steroids, plasma exchange (PLEX) and intravenous immunoglobulin (IVIG). High-dose steroids remain the mainstay of acute treatment. However, evidence is emerging that when optic neuritis is accompanied with certain atypical features that suggest a more unfavorable outcome this mandates special consideration such as early addition of other therapeutic agents or tapering the steroid very slowly. This review will distinguish between typical and atypical neuritis and discuss acute treatment options.

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.

Optic neuritis: current challenges in diagnosis and management

PURPOSE OF REVIEW

The primary aim of this review is to describe the clinical course, salient imaging features, and relevant serological profiles of common optic neuritis (ON) subtypes. Key diagnostic challenges and treatment options will also be discussed.

RECENT FINDINGS

ON is a broad term that describes an inflammatory optic nerve injury arising from a variety of potential causes. ON can occur sporadically, however there is particular concern for co-associated central nervous system (CNS) inflammatory syndromes including multiple sclerosis (MS), neuromyelitis optic spectrum disorders (NMOSD), and myelin oligodendrocyte glycoprotein antibody associated disease (MOGAD). The ON subtypes that often herald MS, NMOSD, and MOGAD differ with respect to serological antibody profile and neuroimaging characteristics, yet there is significant overlap in their clinical presentations. A discerning history and thorough examination are critical to rendering the correct diagnosis.

SUMMARY

Optic neuritis subtypes vary with respect to their long-term prognosis and accordingly, require different acute treatment strategies. Moreover, delays in identifying MOGAD, and certainly NMOSD, can be highly detrimental because affected individuals are vulnerable to permanent vision loss and neurologic disability from relapses.

Optic neuritis and autoimmune optic neuropathies: advances in diagnosis and treatment

Optic neuritis is an inflammatory optic neuropathy that is commonly indicative of autoimmune neurological disorders including multiple sclerosis, myelin-oligodendrocyte glycoprotein antibody-associated disease, and neuromyelitis optica spectrum disorder. Early clinical recognition of optic neuritis is important in determining the potential aetiology, which has bearing on prognosis and treatment. Regaining high-contrast visual acuity is common in people with idiopathic optic neuritis and multiple sclerosis-associated optic neuritis; however, residual deficits in contrast sensitivity, binocular vision, and motion perception might impair vision-specific quality-of-life metrics. In contrast, recovery of visual acuity can be poorer and optic nerve atrophy more severe in individuals who are seropositive for antibodies to myelin oligodendrocyte glycoprotein, AQP4, and CRMP5 than in individuals with typical optic neuritis from idiopathic or multiple-sclerosis associated optic neuritis. Key clinical, imaging, and laboratory findings differentiate these disorders, allowing clinicians to focus their diagnostic studies and optimise acute and preventive treatments. Guided by early and accurate diagnosis of optic neuritis subtypes, the timely use of high-dose corticosteroids and, in some instances, plasmapheresis could prevent loss of high-contrast vision, improve contrast sensitivity, and preserve colour vision and visual fields. Advancements in our knowledge, diagnosis, and treatment of optic neuritis will ultimately improve our understanding of autoimmune neurological disorders, improve clinical trial design, and spearhead therapeutic innovation.

Effect of vitamin A on recovery from the acute phase of multiple sclerosis-related optic neuritis, double-blind, randomized, placebo-controlled trial

Background

Optic neuritis (ON) is one of the main neuro-ophthalmic presentations of multiple sclerosis (MS), and it causes optic nerve atrophy and axonal loss. However, so far, there is no effective treatment to improve long-term outcomes.

Methods

In a double-blind placebo-controlled randomized clinical trial, 50 patients with MS-related ON were allocated into two arms (24 in the control group and 26 in the intervention group) receiving either 25000IU retinyl palmitate or an identical placebo for six months. Visual evoked potential (VEP), visual acuity, and the retinal nerve fiber layer (RNFL) thickness were evaluated and compared before and after the treatment.

Results

RNFL thickness reduction in the affected eyes at sixth month compared to the baseline were 14.81 and 19.46 μm, in the intervention and control groups, respectively (P=0.017). However, VitA therapy did not affect visual acuity and VEP.

Conclusion

Vitamin A supplementation in the patients with acute ON in MS could lessen optic nerve axonal loss.

[Typical and atypical optic neuritis]

Optic neuritis (ON) is one of the most common neuro-ophthalmic causes of vision loss worldwide. Demyelinating ON can be idiopathic or be one of the symptoms of autoimmune demyelinating diseases of the central nervous system (CNS) such as multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Demographic, clinical and radiological signs of ON in these CNS diseases have differences. In this regard, typical and atypical ON are currently distinguished. Recognizing the clinical features that differentiate typical MS-associated ON from atypical ON in NMOSD and MOGAD is important for choosing the correct disease management and treatment strategy. This review summarizes the data from clinical, laboratory, instrumental methods of management used for the differential diagnosis of optic neuritis.

A Practical Approach to the Diagnosis and Management of Optic Neuritis

Optic neuritis (ON), as an umbrella term, refers to a spectrum of inflammatory optic neuropathies arising from a myriad of potential causes. In its most common form, "typical" ON presents as a unilateral, painful subacute vision loss event in young Caucasian women. The Optic Neuritis Treatment Trial (ONTT) has historically guided our treatment of ON, and taught us important lessons about the clinical presentation, visual prognosis, and future risk of multiple sclerosis (MS) diagnosis associated with this condition. However, in the decades since the ONTT, several immune-mediated conditions such as neuromyelitis optica spectrum disorder (NMOSD), and myelin-oligodendrocyte glycoprotein IgG associated disease (MOGAD) have been discovered, complicating the clinical approach to ON. Unlike MS, other central nervous system (CNS) inflammatory conditions are associated with ON subtypes that are potentially blinding, and prone to recurrence. Owing to differences in the clinical presentation, serological biomarkers, radiological findings, and prognostic implications associated with MS ON, NMOSD ON, and MOGAD ON subtypes, it is imperative that clinicians be aware of the diagnostic approach and management options for these conditions.

Detection of lesions in the optic nerve with magnetic resonance imaging using a 3D convolutional neural network

BACKGROUND

Optic neuritis (ON) is one of the first manifestations of multiple sclerosis, a disabling disease with rising prevalence. Detecting optic nerve lesions could be a relevant diagnostic marker in patients with multiple sclerosis.

OBJECTIVES

We aim to create an automated, interpretable method for optic nerve lesion detection from MRI scans.

MATERIALS AND METHODS

We present a 3D convolutional neural network (CNN) model that learns to detect optic nerve lesions based on T2-weighted fat-saturated MRI scans. We validated our system on two different datasets (N = 107 and 62) and interpreted the behaviour of the model using saliency maps.

RESULTS

The model showed good performance (68.11% balanced accuracy) that generalizes to unseen data (64.11%). The developed network focuses its attention to the areas that correspond to lesions in the optic nerve.

CONCLUSIONS

The method shows robustness and, when using only a single imaging sequence, its performance is not far from diagnosis by trained radiologists with the same constraint. Given its speed and performance, the developed methodology could serve as a first step to develop methods that could be translated into a clinical setting.

Anti-PD-1 sintilimab-induced bilateral optic neuropathy in non-small cell lung cancer: A case report and literature review

Anti-PD-1/PD-L1 immunotherapy reactivates T-cell activity to boost the antitumor effect and may trigger autoimmune toxicity in various organ systems involving eyeball and periocular structures at the same time. The rarity of ocular immune-related adverse events should not prevent us from paying attention to this issue because of the bad consequences of visual impairment. This is the first case report of anti-PD-1 sintilimab-induced bilateral optic neuropathy in a 76-year-old man with squamous non-small cell lung cancer (NSCLC). The patient presented with sudden vision blurring without pain in both eyes after three therapeutic cycles of sintilimab plus chemotherapy. Based on the ophthalmic examination, laboratory, and radiological results, our patient was diagnosed with optic neuropathy complication secondary to anti-PD-1 sintilimab treatment. Consequently, sintilimab was held and systemic steroids were administered. The follow-up review showed that the vision recovered and the size of the primary tumor continued to decrease with the response assessment as the partial response. In conclusion, this case report suggested that patients with NSCLC undergoing anti-PD-1/PD-L1 therapy should be closely monitored for ophthalmic assessment and alert to the occurrence of sintilimab-induced optic neuropathy.

Neuromyelitis Optica Spectrum Disorders

PURPOSE OF REVIEW

This article reviews the cardinal clinical features, distinct immunopathology, current diagnostic criteria, relapse-related risk factors, emerging biomarkers, and evolving treatment strategies pertaining to neuromyelitis optica spectrum disorders (NMOSD).

RECENT FINDINGS

The discovery of the pathogenic aquaporin-4 (AQP4)-IgG autoantibody and characterization of NMOSD as an autoimmune astrocytopathy have spearheaded the identification of key immunologic therapeutic targets in this disease, including but not limited to the complement system, the interleukin 6 (IL-6) receptor, and B cells. Accordingly, four recent randomized controlled trials have demonstrated the efficacy of three new NMOSD therapies, namely eculizumab, satralizumab, and inebilizumab.

SUMMARY

Currently, NMOSD poses both diagnostic and treatment challenges. It is debated whether individuals who are seropositive for myelin oligodendrocyte glycoprotein (MOG)-IgG belong within the neuromyelitis optica spectrum. This discussion is fueled by disparities in treatment responses between patients who are AQP4-IgG seropositive and seronegative, suggesting different immunopathologic mechanisms may govern these conditions. As our understanding regarding the immune pathophysiology of NMOSD expands, emerging biomarkers, including serum neurofilament light chain and glial fibrillary acidic protein (GFAP), may facilitate earlier relapse detection and inform long-term treatment decisions. Future research focal points should include strategies to optimize relapse management, restorative treatments that augment neurologic recovery, and practical solutions that promote equitable access to approved therapies for all patients with NMOSD.

Neuromyelitis Optica Spectrum Disorder: From Basic Research to Clinical Perspectives

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system characterized by relapses and autoimmunity caused by antibodies against the astrocyte water channel protein aquaporin-4. Over the past decade, there have been significant advances in the biologic knowledge of NMOSD, which resulted in the IDENTIFICATION of variable disease phenotypes, biomarkers, and complex inflammatory cascades involved in disease pathogenesis. Ongoing clinical trials are looking at new treatments targeting NMOSD relapses. This review aims to provide an update on recent studies regarding issues related to NMOSD, including the pathophysiology of the disease, the potential use of serum and cerebrospinal fluid cytokines as disease biomarkers, the clinical utilization of ocular coherence tomography, and the comparison of different animal models of NMOSD.

Contemporary management challenges in seropositive NMOSD

Neuromyelitis optica spectrum disorders (NMOSD) is an inflammatory disorder of the central nervous system that presents unique management challenges. Neurologic disability in NMOSD is directly linked to acute attacks, therefore, relapse prevention is an overarching goal of care. To this end, identifying effective biomarkers that predict relapse onset and severity is of critical importance. As treatment becomes more precision-based and patient-centred, clinicians will need to be familiar with managing circumstances of particular vulnerability for patients with NMOSD, including infection, pregnancy, and the post-partum phase. The discovery of the pathogenic aquaporin-4 Immunoglobulin G (AQP4 IgG) autoantibody almost 20 years ago ultimately distinguished NMOSD as an autoimmune astrocytopathy and helped spearhead recent therapeutic advancements. Targeted therapies, including eculizumab, satralizumab, and inebilizumab, approved for use in aquaporin-4 immunoglobulin G (AQP4 IgG) seropositive patients with NMOSD will likely improve outcomes, but there are formidable costs involved. Importantly, seronegative patients continue to have limited therapeutic options. Moving forward, areas of research exploration should include relapse prevention, restorative therapies, and initiatives that promote equitable access to approved therapies for all people living with NMOSD.

ABCB1 gene polymorphisms impact the effect of high-dose intravenous methylprednisolone therapy on optic neuritis associated with AQP4-IgG-positive neuromyelitis optica spectrum disorder

WHAT IS KNOWN AND OBJECTIVE

Patients with optic neuritis (ON) have significant individual differences in their response to high-dose intravenous methylprednisolone (HIMP) therapy. This study aims to evaluate the association between gene polymorphisms and the efficacy of HIMP therapy in Chinese Han patients with ON mediated by aquaporin-4 immunoglobulin G antibody (AQP4-IgG) -positive neuromyelitis optica spectrum disorder (NMOSD) or multiple sclerosis (MS).

METHODS

Chinese Han patients with AQP4-IgG⁺ NMOSD-ON or MS-ON were genotyped for four candidate genes: ABCB1 (rs1045642, rs1128503, rs2032582), NR3C1 (rs41423247), TBX21 (rs9910408, rs16947078) and VDR (rs731236, rs1544410, rs7975232, rs2228570). Patients were divided into glucocorticoid resistance (GR) and glucocorticoid sensitivity (GS) groups based on vision acuity (VA) improvement after HIMP treatment. Intergroup comparisons were performed on clinical characteristics, allele and genotype frequencies and haplotype distributions.

RESULTS

A total of 267 patients completed the follow-up, including 120 patients with AQP4-IgG⁺ NMOSD-ON and 147 patients with MS-ON. We observed a significant association between the ABCB1 G2677T/A (rs2032582) polymorphism and glucocorticoid response in AQP4-IgG⁺ NMOSD-ON patients. Changes in VA scores in patients with the GG genotype were significantly lower than those in patients with the T/A T/A genotype (1.07 ± 1.20 vs. 1.77 ± 1.31, p = 0.026). In the GS group, the G allele had a lower frequency than the T/A allele (32.03% vs. 60.16%, p = 0.001). Logistic regression analysis showed that the G2677T/A GG and G T/A genotypes could increase the GR risk 3.53 and 2.67 times compared with the T/A T/A genotype, respectively (OR = 3.534, 95% CI: 1.186-10.527, p = 0.023; OR = 2.675, 95% CI: 1.005-7.123, p = 0.049). In addition, haplotype analysis showed that AQP4-IgG⁺ NMOSD-ON patients with the TAT/TTT haplotype (ABCB1 C3435T-G2677T/A-C1236T) were only 0.54 times more likely to develop GR than those with other haplotypes (OR = 0.542, 95% CI: 0.315-0.932, p = 0.026). However, we did not observe intergroup differences in the MS-ON population.

WHAT IS NEW AND CONCLUSION

Our findings suggest that the G > T/A polymorphism of ABCB1 G2677T/A and the TAT/TTT haplotype played a protective role in HIMP treatment of AQP4-IgG⁺ NMOSD-ON but not MS-ON.

Mesenchymal Stem Cell-Derived Extracellular Vesicles and Their Therapeutic Use in Central Nervous System Demyelinating Disorders

Autoimmune demyelinating diseases-including multiple sclerosis, neuromyelitis optica spectrum disorder, anti-myelin oligodendrocyte glycoprotein-associated disease, acute disseminated encephalomyelitis, and glial fibrillary acidic protein (GFAP)-associated meningoencephalomyelitis-are a heterogeneous group of diseases even though their common pathology is characterized by neuroinflammation, loss of myelin, and reactive astrogliosis. The lack of safe pharmacological therapies has purported the notion that cell-based treatments could be introduced to cure these patients. Among stem cells, mesenchymal stem cells (MSCs), obtained from various sources, are considered to be the ones with more interesting features in the context of demyelinating disorders, given that their secretome is fully equipped with an array of anti-inflammatory and neuroprotective molecules, such as mRNAs, miRNAs, lipids, and proteins with multiple functions. In this review, we discuss the potential of cell-free therapeutics utilizing MSC secretome-derived extracellular vesicles-and in particular exosomes-in the treatment of autoimmune demyelinating diseases, and provide an outlook for studies of their future applications.

Emerging concepts in the treatment of optic neuritis: mesenchymal stem cell-derived extracellular vesicles

BACKGROUND

Optic neuritis (ON) is frequently encountered in multiple sclerosis, neuromyelitis optica spectrum disorder, anti-myelin oligodendrocyte glycoprotein associated disease, and other systemic autoimmune disorders. The hallmarks are an abnormal optic nerve and inflammatory demyelination; episodes of optic neuritis tend to be recurrent, and particularly for neuromyelitis optica spectrum disorder, may result in permanent vision loss.

MAIN BODY

Mesenchymal stem cell (MSC) therapy is a promising approach that results in remyelination, neuroprotection of axons, and has demonstrated success in clinical studies in other neuro-degenerative diseases and in animal models of ON. However, cell transplantation has significant disadvantages and complications. Cell-free approaches utilizing extracellular vesicles (EVs) produced by MSCs exhibit anti-inflammatory and neuroprotective effects in multiple animal models of neuro-degenerative diseases and in rodent models of multiple sclerosis (MS). EVs have potential to be an effective cell-free therapy in optic neuritis because of their anti-inflammatory and remyelination stimulating properties, ability to cross the blood brain barrier, and ability to be safely administered without immunosuppression.

CONCLUSION

We review the potential application of MSC EVs as an emerging treatment strategy for optic neuritis by reviewing studies in multiple sclerosis and related disorders, and in neurodegeneration, and discuss the challenges and potential rewards of clinical translation of EVs including cell targeting, carrying of therapeutic microRNAs, and prolonging delivery for treatment of optic neuritis.

At this Junction…

An 81-year-old woman developed painful vision loss to hand motions in the right eye over a several-day period. Dilated fundus examination revealed no acute pathology, but automated perimetry showed a superotemporal visual field defect in the asymptomatic left eye, suggestive of a junctional scotoma. Magnetic resonance imaging demonstrated enhancement of the right optic nerve extending to its junction with the optic chiasm. The patient's vision failed to improve with intravenous corticosteroids, but demonstrated significant improvement with therapeutic plasma exchange. She was subsequently found to be seropositive for aquaporin-4 autoantibodies, confirming the diagnosis of neuromyelitis optic spectrum disorder.