Myelin-oligodendrocyte-glycoprotein (MOG) autoantibodies as potential markers of severe optic neuritis and subclinical retinal axonal degeneration

Diagnostic Value of Inter-Eye Difference Metrics on OCT for Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis

BACKGROUND AND OBJECTIVES

The 2022 International Consortium for Optic Neuritis diagnostic criteria for optic neuritis (ON) include optical coherence tomography (OCT). The diagnostic value of intereye difference (IED) metrics is high for ON in patients with multiple sclerosis and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorders, but unknown in myelin oligodendrocyte glycoprotein antibody-associated ON (MOG-ON).

METHODS

A multicenter validation study was conducted on the published IED cutoff values (>4% or >4 μm in the macular ganglion cell and inner plexiform layer [mGCIP] or >5% or >5 μm in the peripapillary retinal nerve fiber layer [pRNFL]) in individuals with MOG-ON and age-matched and sex-matched healthy controls (HCs). Structural data were acquired with Spectralis spectral-domain OCT >6 months after ON. We calculated sensitivity, specificity, and receiver operating characteristics for both intereye percentage (IEPD) and absolute difference (IEAD).

RESULTS

A total of 66 individuals were included (MOG-ON N = 33; HCs N = 33). ON was unilateral in 20 and bilateral in 13 subjects. In the pooled analysis, the mGCIP IEPD was most sensitive (92%), followed by the mGCIP IEAD (88%) and pRNFL (84%). The same pattern was found for the specificity (mGCIP IEPD 82%, IEAD 82%; pRNFL IEPD 82%, IEAD 79%).In subgroup analyses, the diagnostic sensitivity was higher in subjects with unilateral ON (>99% for all metrics) compared with bilateral ON (61%-78%).

DISCUSSION

In individuals with MOG-ON, the diagnostic accuracy of OCT-based IED metrics for ON was high, especially of mGCIP IEPD.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that the intereye difference on OCT can distinguish between those with MOG and normal controls.

NMOSD and MOGAD: an evolving disease spectrum

Neuromyelitis optica (NMO) spectrum disorder (NMOSD) is a relapsing inflammatory disease of the CNS, characterized by the presence of serum aquaporin 4 (AQP4) autoantibodies (AQP4-IgGs) and core clinical manifestations such as optic neuritis, myelitis, and brain or brainstem syndromes. Some people exhibit clinical characteristics of NMOSD but test negative for AQP4-IgG, and a subset of these individuals are now recognized to have serum autoantibodies against myelin oligodendrocyte glycoprotein (MOG) - a condition termed MOG antibody-associated disease (MOGAD). Therefore, the concept of NMOSD is changing, with a disease spectrum emerging that includes AQP4-IgG-seropositive NMOSD, MOGAD and double-seronegative NMOSD. MOGAD shares features with NMOSD, including optic neuritis and myelitis, but has distinct pathophysiology, clinical profiles, neuroimaging findings (including acute disseminated encephalomyelitis and/or cortical encephalitis) and biomarkers. AQP4-IgG-seronegative NMOSD seems to be a heterogeneous condition and requires further study. MOGAD can manifest as either a monophasic or a relapsing disease, whereas NMOSD is usually relapsing. This Review summarizes the history and current concepts of NMOSD and MOGAD, comparing epidemiology, clinical features, neuroimaging, pathology and immunology. In addition, we discuss new monoclonal antibody therapies for AQP4-IgG-seropositive NMOSD that target complement, B cells or IL-6 receptors, which might be applied to MOGAD in the near future.

Rapid differentiation of MOGAD and MS after a single optic neuritis

BACKGROUND

Optic neuritis (ON) is a common manifestation of multiple sclerosis (MS) and myelin-oligodendrocyte-glycoprotein IgG-associated disease (MOGAD). This study evaluated the applicability of optical coherence tomography (OCT) for differentiating between both diseases in two independent cohorts.

METHODS

One hundred sixty two patients from seven sites underwent standard OCT and high-contrast visual acuity (HCVA) testing at least 6 months after first ON. Of these, 100 patients (32 MOGAD, 68 MS) comprised the primary investigational cohort, while 62 patients (31 MOGAD, 31 MS) formed a validation cohort. A composite score distinguishing between MOGAD and MS was developed using multivariate logistic regression.

RESULTS

Bilateral simultaneous ON occurred more frequently in MOGAD compared to MS (46.9 vs. 11.8%, p < 0.001). OCT revealed more peripapillary retinal nerve fiber layer (pRNFL) atrophy in all segments in MOGAD compared to predominantly temporal pRNFL atrophy in MS (p < 0.001). HCVA was better preserved in MS (p = 0.007). pRNFL thickness in all except for temporal segments was suitable for differentiating MOGAD and MS. Simultaneous bilateral ON and critical atrophy in nasal (< 58.5 µm) and temporal superior (< 105.5 µm) segments were included into the composite score as three independent predictors for MOGAD. The composite score distinguished MOGAD from MS with 75% sensitivity and 90% specificity in the investigational cohort, and 68% sensitivity and 87% specificity in the validation cohort.

CONCLUSION

Following a single ON-episode, MOGAD exhibits more pronounced global pRNFL atrophy and lower visual acuity after ON compared to MS. The introduced OCT-based composite score enabled differentiation between the two entities across both cohorts.

Comparative Proteomic Analysis of Type 2 Diabetic versus Non-Diabetic Vitreous Fluids

BACKGROUND

Diabetic retinopathy (DR) is a leading cause of vision loss, with complex mechanisms. The study aimed to comprehensively explore vitreous humor of diabetic and non-diabetic individuals, paving the way for identifying the potential molecular mechanisms underlying DR.

METHODS

Vitreous samples from type 2 diabetic and non-diabetic subjects, collected post-mortem, were analyzed using liquid chromatography-mass spectrometry. Pathway enrichment and gene ontology analyses were conducted to identify dysregulated pathways and characterize protein functions.

RESULTS

Pathway analysis revealed dysregulation in multiple metabolic and signaling pathways associated with diabetes, including glycerolipid metabolism, histidine metabolism, and Wnt signaling. Gene ontology analysis identified proteins involved in inflammation, immune response dysregulation, and calcium signaling. Notably, proteins such as Inositol 1,4,5-trisphosphate receptor type 2 (ITPR2), Calcium homeostasis endoplasmic reticulum protein (CHERP), and Coronin-1A (CORO1A) were markedly upregulated in diabetic vitreous, implicating aberrant calcium signaling, inflammatory responses, and cytoskeletal reorganization in DR.

CONCLUSIONS

Our study provides valuable insights into the intricate mechanisms underlying DR and highlights the significance of inflammation, immune dysregulation, and metabolic disturbances in disease progression. Identification of specific proteins as potential biomarkers underscores the multifactorial nature of DR. Future research in this area is vital for advancing therapeutic interventions and translating findings into clinical practice.

Positive Myelin Oligodendrocyte Glycoprotein Antibodies in Isolated Optic Neuritis in a 14-Year-Old Child

Optic neuritis (ON) is a rare condition in the pediatric age group. Patients with optic neuritis can manifest with a wide range of drops in vision, ranging from mild loss to complete loss of vision. Knowing the cause of optic neuritis is an important point that will affect management and prognosis. Anti-myelin oligodendrocyte glycoprotein (anti-MOG) antibody is an autoantibody that causes demyelination of the central nervous system (CNS). Treatment with a high dose of IV steroids followed by oral steroids is the best regimen that shows a favorable vision outcome. We aim to report this case of isolated optic neuritis with a positive anti-myelin oligodendrocyte glycoprotein antibody to highlight the prognosis of myelin oligodendrocyte glycoprotein disease with isolated optic neuritis and how early diagnosis and treatment can affect the visual outcome.

Progression independent of relapses in aquaporin4-IgG-seropositive neuromyelitis optica spectrum disorder, myelin oligodendrocyte glycoprotein antibody-associated disease, and multiple sclerosis

OBJECTIVES

To determine whether progression independent of relapse activity (PIRA) is present in Aquaporin4-IgG-seropositive neuromyelitis optica spectrum disorder (AQP4+NMOSD), Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and relapsing remitting Multiple sclerosis (RRMS).

METHODS

We retrospectively studied the change in EDSS, confirmed disability worsening (CDW) (i.e., PIRA), and new MRI lesions in AQP4+NMOSD, and MOGAD and MS patients. Linear mixed-effect regression model was used to compare the longitudinal changes in EDSS, and Cox regression was used to compare changes in MRI.

RESULTS

The estimated mean ΔEDSS in the AQP4+NMOSD and matched MS group were +0.06 (95%CI: -0.40, +0.52, p = 0.76), and +0.02 (95%CI: -0.05, +0.08, p = 0.6) respectively. The same estimate was -0.08 (95%CI: -0.18, +0.02, p = 0.12) in MOGAD and +0.05 (95%CI: -0.05, +0.15, p = 0.35) in matched MS group. Comparing groups for the presence of CDW (i.e., PIRA) showed that PIRA is more associated with MS compared to AQP4+NMOSD (p = 0.02) and MOGAD (p<0.001). Compared to their matched MS groups, the annualized rate of PIRA was significantly lower in AQP4 (0.08 vs 0.44; p<0.0001), and MOG groups (0.04 vs 0.13; p<0.0001). New T2 or enhancing lesions on brain MRI were higher in MS compared to AQP4+NMOSD and MOGAD patients.

CONCLUSION

Relapse-independent changes in the EDSS, CDW, and MRI activity are not common in AQP4+NMOSD and MOGAD, especially when compared with MS. Since our patients were on relapse prevention therapies at the time of EDSS measurements, our study supports the importance of preventing relapses in AQP4+NMOSD and MOGAD and suggests different pathologic mechanisms of relapse-free neurological damage between MS and AQP4+NMOSD/MOGAD.

Subclinical damage to the contralateral eye in unilateral optic neuritis: A longitudinal study

BACKGROUND

Early detection of subclinical injuries can lead to a correct diagnosis and help control the advancement of the condition. This study aims to investigate the presence of subclinical damage and silent progression to the contralateral eye's visual function and structure in patients experiencing their first episode of unilateral optic neuritis (ON).

METHODS

Fifty patients with first-onset unilateral ON were enrolled in this study. Based on etiology, they were classified as having neuromyelitis optica spectrum disorder-related ON (NMOSD-ON), myelin oligodendrocyte glycoprotein antibody-associated ON (MOG-ON), idiopathic ON (IDON), or multiple sclerosis-related ON (MS-ON). These cases were followed up for one year to determine whether there was any silent progression of visual function and structure in the contralateral non-ON (NON) eye. A gender- and age-matched healthy control (HC) group was included to compare the differences in visual function and structure between the patients with NON eyes and the HC group.

RESULTS

Within two weeks of onset, best-corrected visual acuity (BCVA; P = 0.008), mean deviation (MD) of the visual field (VF) (P = 0.001), and peripapillary retinal nerve fiber layer (pRNFL; P = 0.019) thickness were significantly worse in the NMOSD-NON patients than those in the HC group, while there were no differences in the pRNFL and the ganglion cell-inner plexiform layer (GCIPL) thicknesses and quadrant thicknesses (P > 0.05) of the groups. IDON-NON only showed subclinical damage in VF (P = 0.001) and temporal pRNFL (P = 0.042), while the BCVA, VF, and optic nerve structure (pRNFL, GCIPL) of the MOG-NON patients showed no subclinical damage (P > 0.05). In addition, the one-year follow-up of each NON eye type showed that there was no silent progression in NMOSD-NON, MOG-NON, or IDON-NON. A pairwise comparison of the different types of NON eyes revealed no statistical differences (P > 0.05).

CONCLUSION

Among the patients with unilateral ON, NMOSD-NON and IDON-NON resulted in subclinical damage to the visual function and structure of the contralateral eye within two weeks of onset, whereas MOG-NON did not show any subclinical damage to visual function or structure. Furthermore, these subclinical damages did not show any silent progression during the one-year follow-up period.

The neuro-ophthalmological manifestations of NMOSD and MOGAD-a comprehensive review

Optic neuritis (ON) is one of the most frequently seen neuro-ophthalmic causes of vision loss worldwide. Typical ON is often idiopathic or seen in patients with multiple sclerosis, which is well described in the landmark clinical trial, the Optic Neuritis Treatment Trial (ONTT). However, since the completion of the ONTT, there has been the discovery of aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies, which are biomarkers for neuromyelitis optica spectrum disorder (NMOSD) and MOG antibody-associated disease (MOGAD), respectively. These disorders are associated with atypical ON that was not well characterised in the ONTT. The severity, rate of recurrence and overall outcome differs in these two entities requiring prompt and accurate diagnosis and management. This review will summarise the characteristic neuro-ophthalmological signs in NMOSD and MOGAD, serological markers and radiographic findings, as well as acute and long-term therapies used for these disorders.

Subclinical optic neuritis in pediatric myelin oligodendrocyte glycoprotein antibody-associated disease

BACKGROUND AND OBJECTIVES

The clinical spectrum of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is heterogenous and has evolved over time since the commercial availability of the anti-MOG antibody assay. Subclinical disease activity has been previously reported in the visual pathway, but prevalence data remains limited. We investigated subclinical optic neuritis (ON) based on changes on retinal nerve fiber layer (RNFL) thickness on optic coherence tomography (OCT) in pediatric patients who tested positive for the anti-MOG antibody.

METHODS

In this retrospective, single-center cohort study, we examined children with MOGAD with at least one complete assessment of the anterior visual pathway. Subclinical ON was defined by structural visual system disease in the absence of a subjective complaint of vision loss, pain (particularly with eye movement), or color desaturation.

RESULTS

Records were reviewed from 85 children with MOGAD, 67 of whom (78.8%) had complete records for review. Eleven children (16.4%) had subclinical ON on OCT. Ten had significant reductions in RNFL, of which one had two distinct episodes of decreased RNFL, and one had significant elevations in RNFL. Of the eleven children with subclinical ON, six (54.5%) had a relapsing disease course. We also highlighted the clinical course of three children with subclinical ON detected on longitudinal OCT, including two who had subclinical ON outside of clinical relapses.

CONCLUSION

Children with MOGAD can have subclinical ON events that can manifest as significant reductions or elevations in RNFL on OCT. OCT should be used routinely in the management and monitoring of MOGAD patients.

Peripapillary hyper-reflective ovoid mass-like structures (PHOMS) in AQP4-IgG-positive neuromyelitis optica spectrum disease (NMOSD) and MOG-IgG-associated disease (MOGAD)

BACKGROUND

Peripapillary hyperreflective ovoid mass-like structures (PHOMS) have recently been described as new optical coherence tomography (OCT) marker. It is not yet clear whether the occurrence of PHOMS is disease-specific or disease-spanning. PHOMS have been described in 16-18% of patients with multiple sclerosis (MS). Currently, no data on the prevalence of PHOMS in other demyelinating diseases including aquaporine-4-IgG-positive neuromyelitis optica spectrum disease (AQP4 + NMOSD) or myelin oligodendrocyte glycoprotein-IgG-associated disease (MOGAD) are reported.

METHODS

We performed a cross-sectional, retrospective spectral domain OCT study evaluating the frequency of PHOMS in AQP4 + NMOSD (n = 47) and MOGAD (n = 44) patients. To test the association with retinal neuroaxonal damage, we compared demographic and clinical data as well as retinal layer thicknesses between eyes with vs. eyes without PHOMS.

RESULTS

PHOMS were detected in 17% of AQP4 + NMOSD and 14% of MOGAD patients. Intra-cohort analysis revealed that AQP4 + NMOSD patients with PHOMS were significantly older [mean (years): 57.5 vs. 50.0; p value = 0.04]. We found no association of PHOMS with retinal neuroaxonal degeneration. In addition, in subjects with only one eye affected by PHOMS compared with the unaffected fellow eye, no differences in retinal parameters were observed (n = 4).

CONCLUSIONS

In summary, we found PHOMS in 17% of AQP4 + NMOSD and 14% of MOGAD patients. This is comparable to the prevalence of published MS PHOMS data. Therefore, a disease-specific occurrence of PHOMS is unlikely. Interestingly, PHOMS do not seem to depend on retinal neuroaxonal degeneration.

Retina thickness in clinically affected and unaffected eyes in patients with aquaporin-4 immunoglobulin G antibody seropositive neuromyelitis optica spectrum disorders: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Retina thickness has been studied in patients with neuromyelitis optica spectrum disorders (NMOSD) without distinguishing serostatus and limited data are available in unaffected eyes. We aimed to investigate retina thickness in eyes of aquaporin-4 immunoglobulin G antibody seropositive (AQP4-IgG⁺) NMOSD patients with optic neuritis (AQP4-ON) and without (AQP4-NON).

METHODS

Eligible studies were identified by searching PubMed and Embase. Mean difference (MD, μm) with corresponding 95% confidence interval (CI) was pooled with random-effect models. The primary measures were average thickness of peripapillar retinal nerve fiber layer (pRNFL) centered on optic disc and the combination of ganglion cell layer and inner plexiform layer (GCIPL) at macula.

RESULTS

We included 21 studies enrolling 787 AQP4-IgG⁺ NMOSD patients. Compared with healthy control, pRNFL was thinner in eyes of AQP4-ON (- 32.78, 95% CI [- 36.24, - 29.33]) and AQP4-NON (- 2.76, 95% CI [- 3.94, - 1.58]), so was GICPL in AQP4-ON (-21.38, 95% CI [- 24.01, - 18.74]) and AQP4-NON (95% CI - 2.96, [- 3.91, - 2.00]). Compared with multiple sclerosis with ON, AQP4-ON had thinner pRNFL (- 13.56, 95%CI [- 16.51, - 10.60]) and GCIPL (- 9.12, 95% CI [- 11.88, - 6.36]). AQP4-ON and myelin oligodendrocyte glycoprotein antibody-associated demyelination with ON (MOG-ON) had similar pRNFL (0.59, 95% CI [- 6.61, 7.79]) and GCIPL thickness (- 0.55, 95% CI [- 2.92, 1.82]). AQP4-NON had similar pRNFL and GCIPL thickness to MOG-NON and multiple sclerosis without ON.

CONCLUSIONS

The average thickness of pRNFL and GICPL decreased both in AQP4-ON and AQP4-NON eyes. AQP4-ON eyes had a similar level of pRNFL and GICPL thinning to MOG-ON eyes, so did AQP4-NON to MOG-NON eyes.

Retinal structural and microvascular changes in myelin oligodendrocyte glycoprotein antibody disease and neuromyelitis optica spectrum disorder: An OCT/OCTA study

Purpose

To compare the optical coherence tomography (OCT)/OCT angiography (OCTA) measures in patients with neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD).

Methods

Twenty-one MOG, 21 NMOSD, and 22 controls were enrolled in our study. The retinal structure [retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL)] was imaged and assessed with the OCT; OCTA was used to image the macula microvasculature [superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP)]. Clinical information such as disease duration, visual acuity, and frequency of optic neuritis and disability was recorded for all patients.

Results

Compared with NMOSD patients, MOGAD patients showed significantly reduced SVP density (P = 0.023). No significant difference (P > 0.05) was seen in the microvasculature and structure when NMOSD-ON was compared with MOG-ON. In NMOSD patients, EDSS, disease duration, reduced visual acuity, and frequency of ON significantly correlated (P < 0.05) with SVP and ICP densities; in MOGAD patients, SVP correlated with EDSS, duration, reduced visual acuity, and frequency of ON (P < 0.05), while DCP density correlated with disease duration, visual acuity, and frequency of ON.

Conclusions

Distinct structural and microvascular changes were identified in MOGAD patients compared with NMOSD patients suggesting that the pathological mechanisms are different in NMOSD and MOGAD. Retinal imaging via the SS-OCT/OCTA might have the potential to be used as a clinical tool to evaluate the clinical features associated with NMOSD and MOGAD.

Characteristic retinal atrophy pattern allows differentiation between pediatric MOGAD and MS after a single optic neuritis episode

BACKGROUND

Optic neuritis (ON) is the most prevalent manifestation of pediatric multiple sclerosis (MSped) and myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGADped) in children > 6 years. In this study, we investigated retinal atrophy patterns and diagnostic accuracy of optical coherence tomography (OCT) in differentiating between both diseases after the first ON episode.

METHODS

Patients were retrospectively identified in eight tertial referral centers. OCT, VEP and high/low-contrast visual acuity (HCVA/LCVA) have been investigated > 6 months after the first ON. Prevalence of pathological OCT findings was identified based on data of 144 age-matched healthy controls.

RESULTS

Thirteen MOGADped (10.7 ± 4.2 years, F:M 8:5, 21 ON eyes) and 21 MSped (14.3 ± 2.4 years, F:M 19:2, 24 ON eyes) patients were recruited. We observed a significantly more profound atrophy of both peripapillary and macular retinal nerve fiber layer in MOGADped compared to MSped (pRNFL global: 68.2 ± 16.9 vs. 89.4 ± 12.3 µm, p < 0.001; mRNFL: 0.12 ± 0.01 vs. 0.14 ± 0.01 mm3, p < 0.001). Neither other macular layers nor P100 latency differed. MOGADped developed global atrophy affecting all peripapillary segments, while MSped displayed predominantly temporal thinning. Nasal pRNFL allowed differentiation between both diseases with the highest diagnostic accuracy (AUC = 0.902, cutoff < 62.5 µm, 90.5% sensitivity and 70.8% specificity for MOGADped). OCT was also substantially more sensitive compared to VEP in identification of ON eyes in MOGAD (pathological findings in 90% vs. 14%, p = 0.016).

CONCLUSION

First MOGAD-ON results in a more severe global peripapillary atrophy compared to predominantly temporal thinning in MS-ON. Nasal pRNFL allows differentiation between both diseases with the highest accuracy, supporting the additional diagnostic value of OCT in children with ON.

Application of the International Interocular Difference Thresholds into Practice: Localising the Patient Experience

Demyelinating diseases of the central nervous system (CNS) often have neuro-ophthalmological manifestations, and retinal examination can be helpful in making the diagnosis. The latest iteration of optical coherence tomography (OCT)-based criteria for optic neuritis in multiple sclerosis has been developed in the research realm, but its application to clinical practice, and to the more uncommon demyelinating diseases requires further study. The ability to use OCT data to distinguish between various CNS demyelinating disorders could provide additional paraclinical tools to accurately diagnose patients. Furthermore, neuro-ophthalmological testing can define the extent of inflammatory damage in the CNS, independent of patient-reported history. New referrals for OCT at a tertiary multiple sclerosis and neuro-immunology referral centre (n = 167) were analysed retrospectively for the self-reporting of optic neuritis, serological test results, and diagnosis. Only approximately 30% of patients with a clinical history of unilateral optic neuritis solely had a unilateral optic neuropathy, nearly 40% of those subjects actually having evidence of bilateral optic neuropathies. Roughly 30% of patients reporting a history of bilateral optic neuritis did not have any evidence of structural disease, with 20% of these patients having a separate, intervenable diagnosis noted on macular scans. OCT is a useful adjunct diagnostic tool in the evaluation of demyelinating disease and has the ability to aid in a more accurate diagnosis for patients. Application of the international interocular difference thresholds to a clinical patient population generally reproduces the original results, emphasising their appropriateness. The analysis distinguishing the demyelinating diseases needs to be replicated in a blinded, multi-centre setting.

Optical Coherence Tomography in Chronic Relapsing Inflammatory Optic Neuropathy, Neuromyelitis Optica and Multiple Sclerosis: A Comparative Study

Purpose: To examine the optical coherence tomography (OCT) features of the retina in patients with chronic relapsing inflammatory optic neuropathy (CRION) and compare them with those of neuromyelitis optica spectrum disorder (NMOSD), relapsing-remitting multiple sclerosis (RRMS) with and without optic neuritis (ON), and healthy controls (HC). Methods: In this retrospective cross-sectional study, we used spectral domain OCT to evaluate the retinal structure of 14 participants with CRION, 22 with NMOSD, 40 with RRMS with unilateral ON, and 20 HC. The peripapillary retinal nerve fiber layer (pRNFL), total macular volume (TMV), and papillomacular bundle (PMB) were measured, and intra-retinal segmentation was performed to obtain the retinal nerve fiber (RNFL), ganglion cell (GCL), inner plexiform (IPL), inner nuclear (INL), outer plexiform (OPL) and outer nuclear (ONL) layer volumes. Results: The global pRNFL [39.33(±1.8) µm] and all its quadrants are significantly thinner in CRION compared with all other groups (p < 0.05). CRION patients have decreased volumes of TMV, RNFL, GCL, and IPL compared with all other groups (p < 0.05). Conclusion: Severe thinning in pRNFL and thinning in intra-retinal segments of IPL, GCL, RNFL, and TMV could be helpful in differentiating CRION from NMOSD and RRMS.

Longitudinal retinal changes in MOGAD

OBJECTIVE

Patients with myelin oligodendrocyte glycoprotein antibody (MOG-IgG) associated disease (MOGAD) suffer from severe optic neuritis (ON) leading to retinal neuro-axonal loss, which can be quantified by optical coherence tomography (OCT). We assessed whether ON-independent retinal atrophy can be detected in MOGAD.

METHODS

Eighty MOGAD patients and 139 healthy controls (HC) were included. OCT data was acquired with 1) Spectralis spectral domain OCT (MOGAD (N=66) and HC (N=103)) and 2) Cirrus HD-OCT (MOGAD (N=14) and HC (N=36)). Macular combined ganglion cell and inner plexiform layer (GCIPL) and peripapillary retinal nerve fibre layer (pRNFL) were quantified.

RESULTS

At baseline, GCIPL and pRNFL were lower in MOGAD eyes with a history of ON (MOGAD-ON) compared with MOGAD eyes without a history of ON (MOGAD-NON) and HC (p<0.001). MOGAD-NON eyes had lower GCIPL volume compared to HC (p<0.001) in the Spectralis, but not in the Cirrus cohort. Longitudinally (follow-up up to 3 years), MOGAD-ON with ON within the last 6-12 months before baseline exhibited greater pRNFL thinning than MOGAD-ON with an ON >12 months ago (p<0.001). The overall MOGAD cohort did not exhibit faster GCIPL thinning compared with HC.

INTERPRETATION

Our study suggests the absence of attack-independent retinal damage in MOGAD. Yet, ongoing neuroaxonal damage or oedema resolution seems to occur for up to 12 months after ON, which is longer than what has been reported with other ON forms. These findings support that the pathomechanisms underlying optic nerve involvement and the evolution of OCT retinal changes after ON is distinct in MOGAD. This article is protected by copyright. All rights reserved.

A Longitudinal Comparison of the Recovery Patterns of Optic Neuritis with MOG Antibody-Seropositive and AQP4 Antibody-Seropositive or -Seronegative for Both Antibodies

In this study, the aim is to compare the recovery pattern among patients with acute myelin oligodendrocyte glycoprotein antibody-seropositive optic neuritis (MOG-Ab + ON) attacks and aquaporin-4 antibody-seropositive ON (AQP4-Ab + ON) or -seronegative ON. At the onset of the first-ever ON attack, the thickness of RNFL (RNFLt) in the MOG-Ab + ON group was significantly thicker than others ( $P<0.05$ ), while visual function damage was not significantly different to other groups. One month to six months after onset, the MOG-Ab + ON group showed significantly better visual function ( $P<0.05$ ) than the other two groups, while the RNFLt showed no significant difference among the three groups ( $P>0.05$ ). MOG-Ab + ON and AQP4-Ab + ON groups showed rapid recovery in the first month and then plateaued. The annual relapse rate was significantly higher in MOG-Ab + ON and AQP4-Ab + ON groups than seronegative ON. The relapse interval of the MOG-Ab + ON group (9.00 ± 7.86 months) was significantly shorter than that of the AQP4-Ab + ON group (45.76 ± 37.82 months) ( $P<0.05$ ) but showed no significant difference from that of the seronegative ON group ( $P>0.05$ ). To sum up, the recovery patterns were different among these three types of ON. RNFLt was not parallel to the recovery of visual function among these types of ON. MOG-Ab + ON had the mildest visual function damage but the most substantial RNFL changes, while AQP4-Ab + ON suffered the worst function damage. MOG-Ab + ON had a similar relapse rate as AQP4-Ab + ON but a shorter interval, indicating that relapse prevention was necessary and should be initiated as early as possible.

Astrocytic outer retinal layer thinning is not a feature in AQP4-IgG seropositive neuromyelitis optica spectrum disorders

BACKGROUND

Patients with anti-aquaporin-4 antibody seropositive (AQP4-IgG+) neuromyelitis optica spectrum disorders (NMOSDs) frequently suffer from optic neuritis (ON) leading to severe retinal neuroaxonal damage. Further, the relationship of this retinal damage to a primary astrocytopathy in NMOSD is uncertain. Primary astrocytopathy has been suggested to cause ON-independent retinal damage and contribute to changes particularly in the outer plexiform layer (OPL) and outer nuclear layer (ONL), as reported in some earlier studies. However, these were limited in their sample size and contradictory as to the localisation. This study assesses outer retinal layer changes using optical coherence tomography (OCT) in a multicentre cross-sectional cohort.

METHOD

197 patients who were AQP4-IgG+ and 32 myelin-oligodendrocyte-glycoprotein antibody seropositive (MOG-IgG+) patients were enrolled in this study along with 75 healthy controls. Participants underwent neurological examination and OCT with central postprocessing conducted at a single site.

RESULTS

No significant thinning of OPL (25.02±2.03 µm) or ONL (61.63±7.04 µm) were observed in patients who were AQP4-IgG+ compared with patients who were MOG-IgG+ with comparable neuroaxonal damage (OPL: 25.10±2.00 µm; ONL: 64.71±7.87 µm) or healthy controls (OPL: 24.58±1.64 µm; ONL: 63.59±5.78 µm). Eyes of patients who were AQP4-IgG+ (19.84±5.09 µm, p=0.027) and MOG-IgG+ (19.82±4.78 µm, p=0.004) with a history of ON showed parafoveal OPL thinning compared with healthy controls (20.99±5.14 µm); this was not observed elsewhere.

CONCLUSION

The results suggest that outer retinal layer loss is not a consistent component of retinal astrocytic damage in AQP4-IgG+ NMOSD. Longitudinal studies are necessary to determine if OPL and ONL are damaged in late disease due to retrograde trans-synaptic axonal degeneration and whether outer retinal dysfunction occurs despite any measurable structural correlates.

A review on 3D printing functional brain model

Modern neuroscience increasingly relies on 3D models to study neural circuitry, nerve regeneration, and neural disease. Several different biofabrication approaches have been explored to create 3D neural tissue model structures. Among them, 3D bioprinting has shown to have great potential to emerge as a high-throughput/high precision biofabrication strategy that can address the growing need for 3D neural models. Here, we have reviewed the design principles for neural tissue engineering. The main challenge to adapt printing technologies for biofabrication of neural tissue models is the development of neural bioink, i.e., a biomaterial with printability and gelation properties and also suitable for neural tissue culture. This review shines light on a vast range of biomaterials as well as the fundamentals of 3D neural tissue printing. Also, advances in 3D bioprinting technologies are reviewed especially for bioprinted neural models. Finally, the techniques used to evaluate the fabricated 2D and 3D neural models are discussed and compared in terms of feasibility and functionality.

Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis-A Review

ABSTRACT

Our understanding of demyelinating optic neuritis has substantially evolved over the past 2 decades. With advancements in serological testing, antibodies against myelin oligodendrocyte glycoprotein (MOG) have been recently discovered in a distinct subset of demyelinating neuroinflammatory disease. Although MOG-immunoglobulin G (IgG)-associated disorder (MOGAD) has previously been seen as a component of neuromyelitis optica spectrum disorder (NMOSD), evidence increasingly suggests that it should be distinguished as a separate condition. The distinction of MOGAD from aquaporin-4 IgG NMOSD is imperative as treatment plans need to be tailored to its unique disease course and prognosis. The purpose of this review is to explore the nature and outcomes of MOGAD optic neuritis to help guide acute and long-term immunosuppressive treatment decisions.

Clinical and neuroimaging findings in MOGAD-MRI and OCT

Myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGAD) are rare in both children and adults, and have been recently suggested to be an autoimmune neuroinflammatory group of disorders that are different from aquaporin-4 autoantibody-associated neuromyelitis optica spectrum disorder and from classic multiple sclerosis. In-vivo imaging of the MOGAD patient central nervous system has shown some distinguishing features when evaluating magnetic resonance imaging of the brain, spinal cord and optic nerves, as well as retinal imaging using optical coherence tomography. In this review, we discuss key clinical and neuroimaging characteristics of paediatric and adult MOGAD. We describe how these imaging techniques may be used to study this group of disorders and discuss how image analysis methods have led to recent insights for consideration in future studies.

Evidence for and against subclinical disease activity and progressive disease in MOG antibody disease and neuromyelitis optica spectrum disorder

Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) and aquaporin-4 IgG seropositive neuromyelitis optica spectrum disorder (AQP4-IgG+ NMOSD) are generally considered to be relapsing disorders, without clinical progression or subclinical disease activity outside of clinical relapses, in contrast to multiple sclerosis (MS). With advances in the diagnosis and treatment of these conditions, prolonged periods of remission without relapses can be achieved, and the question of whether progressive disease courses can occur has re-emerged. In this review, we focus on studies exploring evidence for and against relapse-independent clinical progression and/or subclinical disease activity in patients with MOGAD and AQP4-IgG+ NMOSD.

A comparative study of alteration in retinal layer segmentation alteration by SD-OCT in neuromyelitis optica spectrum disorders: A systematic review and meta-analysis

Background

To evaluate the feature of different retinal layer segmentation in neuromyelitis optica spectrum disorders (NMOSD) with spectral-domain optical coherence tomography (SD-OCT) and to compare it with that in multiple sclerosis (MS), healthy controls (HC), and idiopathic optic neuritis (ION).

Methods

We retrieved four electronic databases, including Pubmed, Embase, Cochrane Library, and Web of Science from inception to September 1st, 2021. A meta-analysis was performed to compare different retinal layer segmentation thicknesses between patients with or without a history of optic neuritis (ON) in NMOSD and the control group, including patients with MS, HC, and ION.

Results

Forty-two studies were included and the interval between the last ON onset and examination was greater than 3 months. Compared with that in HC eyes, the loss of retinal nerve fiber layer (RNFL) and macular ganglion cell and inner plexiform layer (GC-IPL) was serious in NMOSD eye especially after ON. Moreover, compared with that in ION eyes or MS-related-ON eyes, the injury to the peripapillary retinal nerve fiber layer (pRNFL) was severe in NMOSD-related-ON eyes. In addition, the correlation coefficient between pRNFL and prognostic visual acuity was 0.43. However, the one-arm study revealed the inner nuclear layer (INL) was thickened in NMOSD-related-ON eyes compared with HC eyes.

Conclusions

Inclusion of the RNFL and macular GC-IPL is recommended for monitoring disease progression and attention should be paid to changes in the INL.

Retinal optical coherence tomography and magnetic resonance imaging in neuromyelitis optica spectrum disorders and MOG-antibody associated disorders: an updated review

INTRODUCTION

Neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein IgG antibody-associated disorders (MOGAD) comprise two groups of rare neuroinflammatory diseases that cause attack-related damage to the central nervous system (CNS). Clinical attacks are often characterized by optic neuritis, transverse myelitis, and to a lesser extent, brainstem encephalitis/area postrema syndrome. Retinal optical coherence tomography (OCT) is a non-invasive technique that allows for in vivo thickness quantification of the retinal layers. Apart from OCT, magnetic resonance imaging (MRI) plays an increasingly important role in NMOSD and MOGAD diagnosis based on the current international diagnostic criteria. Retinal OCT and brain/spinal cord/optic nerve MRI can help to distinguish NMOSD and MOGAD from other neuroinflammatory diseases, particularly from multiple sclerosis, and to monitor disease-associated CNS-damage.

AREAS COVERED

This article summarizes the current status of imaging research in NMOSD and MOGAD, and reviews the clinical relevance of OCT, MRI and other relevant imaging techniques for differential diagnosis, screening and monitoring of the disease course.

EXPERT OPINION

Retinal OCT and MRI can visualize and quantify CNS damage in vivo, improving our understanding of NMOSD and MOGAD pathology. Further efforts on the standardization of these imaging techniques are essential for implementation into clinical practice and as outcome parameters in clinical trials.

Age-dependent favorable visual recovery despite significant retinal atrophy in pediatric MOGAD: how much retina do you really need to see well?

Background

To investigate age-related severity, patterns of retinal structural damage, and functional visual recovery in pediatric and adult cohorts of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) optic neuritis (ON).

Methods

All MOGAD patients from the 5 participating centers were included. Patients with initial manifestation <18 years were included in the pediatric (MOGAD^ped) cohort and patients with ≥18 years in the adult (MOGAD^adult) cohort. For patients with MOGAD ON, examinations at least ≥6 months after ON onset were included in the analyses. Using spectral domain optical coherence tomography (SD-OCT), we acquired peripapillary retinal nerve fiber layer thickness (pRNFL) and volumes of combined ganglion cell and inner plexiform layer (GCIPL). High- and 2.5% low-contrast visual acuity (HCVA, LCVA) and visual-evoked potentials (VEP) were obtained.

Results

Twenty MOGAD^ped (10.3±3.7 years, 30 MOGAD ON eyes) and 39 MOGAD^adult (34.9±11.6 years, 42 MOGAD ON eyes) patients were included. The average number of ON episodes per ON eye was similar in both groups (1.8±1.3 and 2.0±1.7). In both pediatric and adult MOGAD, ON led to pronounced neuroaxonal retinal atrophy (pRNFL: 63.1±18.7 and 64.3±22.9 μm; GCIPL: 0.42±0.09 and 0.44±0.13 mm³, respectively) and moderate delay of the VEP latencies (117.9±10.7 and 118.0±14.5 ms). In contrast, visual acuity was substantially better in children (HCVA: 51.4±9.3 vs. 35.0±20.6 raw letters, p=0.001; LCVA: 22.8±14.6 vs. 13.5±16.4, p=0.028). Complete visual recovery (HCVA-logMAR 0.0) occurred in 73.3% of MOGAD^ped and 31% MOGAD^adults ON eyes, while 3.3% and 31% demonstrated moderate to severe (logMAR > 0.5) visual impairment. Independent of retinal atrophy, age at ON onset significantly correlated with visual outcome.

Conclusion

Pediatric MOGAD ON showed better visual recovery than adult MOGAD ON despite profound and almost identical neuroaxonal retinal atrophy. Age-related cortical neuroplasticity may account for the substantial discrepancy between structural changes and functional outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02160-9.

Overlapping syndrome of anti-N-methyl-D-aspartate receptor encephalitis and anti-myelin oligodendrocyte glycoprotein inflammatory demyelinating diseases: A distinct clinical entity?

BACKGROUND

The co-existence of anti-N-methyl-D-aspartate receptor encephalitis (NMDARe) and anti-myelin oligodendrocyte glycoprotein (MOG) antibody disease has sparsely been reported, which needs to be investigated.

METHOD

Among the patients with NMDARe in Xuanwu Hospital, MOG antibody disease and NMDARe overlapping syndrome (MNOS) were retrospectively identified. We combined our data with those from previously reported cases to characterize this new entity.

RESULT

There were 45 patients with MNOS with a median onset age of 20. A total of 97.8% of the patients had symptoms of encephalitis; 68.9% of the patients had symptoms of demyelination, including optic neuritis (ON) (37.9%), longitudinally extensive transverse myelitis (LETM) (31.0%) and acute disseminated encephalomyelitis (ADEM) (27.6%). Abnormal signals on magnetic resonance imaging (MRI) usually involved cortical (46.7%), subcortical (31.1%) and basal ganglia (26.7%) lesions, as well as infratentorial (48.9%) and spinal cord (28.9%) lesions. No tumours were found. A total of 62.2% of the patients relapsed, with recurrence rates of 66.7% and 50.0% for those treated with first-line therapy alone and in combination with second-line immunotherapy, respectively. The pathological changes from the biopsy indicated immune-mediated inflammatory demyelination. Although some patients may have residual deficits, 93.3% of the patients became functionally independent.

CONCLUSION

The possibility of MNOS should be considered when patients diagnosed with anti-NMDARe simultaneously or sequentially develop ON, LETM or ADEM. MNOS occurred without tumour association, and inflammatory demyelination may be the pathological change. Steroids combined with second-line immunotherapy can help to reduce high recurrence rates, and most patients will have substantial recovery.

Alterations in the Retinal Vascular Network and Structure in Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis: A Longitudinal OCTA Study

Purpose: To investigate the longitudinal microstructural and microvascular changes in patients with myelin oligodendrocyte glycoprotein antibody-associated optic neuritis (MOG-ON) without new attacks.Methods: We included 20 eyes of 12 MOG-ON patients without new attacks during the follow-up and 24 eyes of 12 age- and sex-matched healthy controls.Results: The BCVA, retinal vessels and structure were significantly lower in MOG-ON eyes than in healthy eyes(all P < .05). In MOG-ON eyes, the BCVA (p = .408) and mean deviation (p = .854) were not significantly decreased at the follow-up visit. However, there were small, significant decreases in parafoveal vessel density (p = .026), peripapillary vessel density (p = .008), and RNFL thickness (p = .03), but not GCIPL thickness (p = .107).Conclusions: Ongoing deterioration was observed in RNFL thickness and parafoveal and peripapillary vessel density, but not GCIPL thinning, in MOG-ON eyes without a new attack of ON.

Neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein associated disorder-optic neuritis: a comprehensive review of diagnosis and treatment

Optic neuritis (ON) is the most common cause of acute optic neuropathy in patients younger than 50 years of age and is most frequently idiopathic or associated with multiple sclerosis. However, the discovery of aquaporin-4 immunoglobulin G (IgG) and myelin oligodendrocyte glycoprotein (MOG)-IgG as biomarkers for two separate central nervous system inflammatory demyelinating diseases has revealed that neuromyelitis optica spectrum disorder (NMSOD) and MOG-IgG-associated disease (MOGAD) are responsible for clinically distinct subsets of ON. NMOSD-ON and MOGAD-ON both demonstrate tendencies for bilateral optic nerve involvement and often exhibit a relapsing course with the potential for devastating long-term visual outcomes. Early and accurate diagnosis is therefore essential. This review will summarize the current understanding of the clinical spectra of NMOSD and MOGAD, the radiographic and serological findings which support their diagnoses, and the current evidence behind various acute and long-term therapeutic strategies for ON related to these conditions. A particular emphasis is placed on a number of recent multi-centre randomized placebo-controlled trials, which provide the first level I evidence for long-term treatment of NMOSD.

Intravenous immunoglobulin treatment for steroid-resistant optic neuritis: a multicenter, double-blind, randomized, controlled phase III study

PURPOSE

To evaluate the efficacy and safety of intravenous "freeze-dried sulfonated human normal immunoglobulin (GGS)" in patients with steroid-resistant optic neuritis (ON).

STUDY DESIGN

Multicenter, prospective, double-blind, parallel-group, randomized controlled trial.

METHODS

Patients with steroid-resistant acute ON were randomly assigned to receive either intravenous GGS (GGS group) or intravenous methylprednisolone (steroid pulse [SP] group). Visual acuity (logarithm of the minimum angle of resolution [logMAR]), mean deviation (MD) value of the Humphrey Field Analyzer, and critical flicker fusion frequency were measured as efficacy endpoints; adverse events (AEs) were assessed as the safety endpoint.

RESULTS

Thirty-two patients (16 patients/group) received the study drugs. The primary endpoint, change in logMAR at week 2 compared to baseline, showed no statistically significant intergroup difference. However, compared with the SP group, change in the GGS group was increasingly indicative of visual improvement, with least squares mean difference of > 0.3 logMAR. On post-hoc analyses, the percentage of patients in the GGS and SP groups with improvement by ≥ 0.3 logMAR at week 2 were 75.0% and 31.3%, respectively. Changes in MD values at week 2 compared to baseline were 9.258  ±  8.296 (mean ± standard deviation) dB and 3.175  ±  6.167 dB in the GGS and SP groups, respectively. These results showed statistically significant intergroup differences (visual acuity improvement, P = 0.032; change in MD values, P = 0.030). No clinically significant AEs were observed.

CONCLUSION

Our results suggest that intravenous immunoglobulin could be a safe and efficacious therapeutic option for prompt treatment of steroid-resistant acute ON.

TRIAL REGISTRATION

JapicCTI-132080.

The role of KIR positive NK cells in diseases and its importance in clinical intervention

Natural killer (NK) cells are essential for the elimination of the transformed and cancerous cells. Killer cell immunoglobulin-like receptors (KIRs) which expressed by T and NK cells, are key regulator of NK cell function. The KIR and their ligands, MHC class I (HLA-A, B and C) molecules, are highly polymorphic and their related genes are located on 19 q13.4 and 6 q21.3 chromosomes, respectively. It is clear that particular interaction between the KIRs and their related ligands can influence on the prevalence, progression and outcome of several diseases, like complications of pregnancy, viral infection, autoimmune diseases, and hematological malignancies. The mechanisms of immune signaling in particular NK cells involvement in causing pathological conditions are not completely understood yet. Therefore, better understanding of the molecular mechanism of KIR-MHC class I interaction could facilitate the treatment strategy of diseases. The present review focused on the main characteristics and functional details of various KIR and their combination with related ligands in diseases and also highlights ongoing efforts to manipulate the key checkpoints in NK cell-based immunotherapy.

Cohort profile: a collaborative multicentre study of retinal optical coherence tomography in 539 patients with neuromyelitis optica spectrum disorders (CROCTINO)

PURPOSE

Optical coherence tomography (OCT) captures retinal damage in neuromyelitis optica spectrum disorders (NMOSD). Previous studies investigating OCT in NMOSD have been limited by the rareness and heterogeneity of the disease. The goal of this study was to establish an image repository platform, which will facilitate neuroimaging studies in NMOSD. Here we summarise the profile of the Collaborative OCT in NMOSD repository as the initial effort in establishing this platform. This repository should prove invaluable for studies using OCT to investigate NMOSD.

PARTICIPANTS

The current cohort includes data from 539 patients with NMOSD and 114 healthy controls. These were collected at 22 participating centres from North and South America, Asia and Europe. The dataset consists of demographic details, diagnosis, antibody status, clinical disability, visual function, history of optic neuritis and other NMOSD defining attacks, and OCT source data from three different OCT devices.

FINDINGS TO DATE

The cohort informs similar demographic and clinical characteristics as those of previously published NMOSD cohorts. The image repository platform and centre network continue to be available for future prospective neuroimaging studies in NMOSD. For the conduct of the study, we have refined OCT image quality criteria and developed a cross-device intraretinal segmentation pipeline.

FUTURE PLANS

We are pursuing several scientific projects based on the repository, such as analysing retinal layer thickness measurements, in this cohort in an attempt to identify differences between distinct disease phenotypes, demographics and ethnicities. The dataset will be available for further projects to interested, qualified parties, such as those using specialised image analysis or artificial intelligence applications.

AQP4-IgG and MOG-IgG Related Optic Neuritis-Prevalence, Optical Coherence Tomography Findings, and Visual Outcomes: A Systematic Review and Meta-Analysis

Background: Optic neuritis (ON) is a cardinal manifestation of multiple sclerosis (MS), aquaporin-4 (AQP4)-IgG-, and myelin oligodendrocyte glycoprotein (MOG)-IgG-associated disease. However, the prevalence of AQP4-IgG seropositivity and MOG-IgG seropositivity in isolated ON is unclear, and studies comparing visual outcomes and optical coherence tomography (OCT)-derived structural retinal measures between MS-ON, AQP4-ON, and MOG-ON eyes are limited by small sample sizes. Objectives: (1) To assess the prevalence of AQP4-IgG and MOG-IgG seropositivity among patients presenting with isolated ON; (2) to compare visual outcomes and OCT measures between AQP4-ON, MOG-ON, and MS-ON eyes. Methods: In this systematic review and meta-analysis, a total of 65 eligible studies were identified by PubMed search. Statistical analyses were performed with random effects models. Results: In adults with isolated ON, AQP4-IgG seroprevalence was 4% in non-Asian and 27% in Asian populations, whereas MOG-IgG seroprevalence was 8 and 20%, respectively. In children, AQP4-IgG seroprevalence was 0.4% in non-Asian and 15% in Asian populations, whereas MOG-IgG seroprevalence was 47 and 31%, respectively. AQP4-ON eyes had lower peri-papillary retinal nerve fiber layer (pRNFL; -11.7 μm, 95% CI: -15.2 to -8.3 μm) and macular ganglion cell + inner plexiform layer (GCIPL; -9.0 μm, 95% CI: -12.5 to -5.4 μm) thicknesses compared with MS-ON eyes. Similarly, pRNFL (-11.2 μm, 95% CI: -21.5 to -0.9 μm) and GCIPL (-6.1 μm, 95% CI: -10.8 to -1.3 μm) thicknesses were lower in MOG-ON compared to MS-ON eyes, but did not differ between AQP4-ON and MOG-ON eyes (pRNFL: -1.9 μm, 95% CI: -9.1 to 5.4 μm; GCIPL: -2.6 μm, 95% CI: -8.9 to 3.8 μm). Visual outcomes were worse in AQP4-ON compared to both MOG-ON (mean logMAR difference: 0.60, 95% CI: 0.39 to 0.81) and MS-ON eyes (mean logMAR difference: 0.68, 95% CI: 0.40 to 0.96) but were similar in MOG-ON and MS-ON eyes (mean logMAR difference: 0.04, 95% CI: -0.05 to 0.14). Conclusions: AQP4-IgG- and MOG-IgG-associated disease are important diagnostic considerations in adults presenting with isolated ON, especially in Asian populations. Furthermore, MOG-IgG seroprevalence is especially high in pediatric isolated ON, in both non-Asian and Asian populations. Despite a similar severity of GCIPL and pRNFL thinning in AQP4-ON and MOG-ON, AQP4-ON is associated with markedly worse visual outcomes.

Differences in morphology and visual function of myelin oligodendrocyte glycoprotein antibody and multiple sclerosis associated optic neuritis

Background

Myelin oligodendrocyte glycoprotein immunoglobulin G associated optic neuritis (MOG-ON) is a recently described entity. Recent studies have shown that MOG-ON has a more severe clinical presentation than classic optic neuritis (ON).

Objective

This study aimed to define morphological characteristics of MOG-ON, correlate these with clinical characteristics and compare them with multiple sclerosis associated ON (MS-ON) and healthy controls (CTRL).

Methods

In a retrospective study, we included MOG-ON and MS-ON patients seen between 2011 and 2018 at the University Hospital Bern. Data from clinical examination, perimetry, and optical coherence tomography (OCT) were analyzed.

Results

A total of 66 eyes of 43 patients were included; 22 MS-ON and 33 CTRL eyes were sex- and age-matched to 11 MOG-ON eyes. We found significantly worse visual acuity at nadir, but better recovery and thinner global peripapillary retinal nerve fiber layer thickness in MOG-ON patients compared to MS-ON patients. Both groups exhibited irregular thinning of the macular ganglion cell layer. Furthermore, the visual acuity and visual field parameters correlated to retinal layer thickness only in MOG-ON eyes.

Conclusion

In comparison to MS-ON, MOG-ON is associated with more prominent acute vision loss and more pronounced global thinning of the pRNFL. Both entities result in similar final visual acuity and atrophy of the macular ganglion cell layer.

Visual field loss and structure-function relationships in optic neuritis associated with myelin oligodendrocyte glycoprotein antibody

BACKGROUND

A paradoxical discrepancy between severe peripapillary retinal nerve fiber layer (pRNFL) atrophy and good visual outcome had been reported in patients with myelin oligodendrocyte glycoprotein-immunoglobulin G (MOG-IgG)-associated optic neuritis (ON). However, only visual acuity (VA) was assessed.

OBJECTIVES

To study visual field (VF) outcomes of patients with MOG-IgG-associated ON and evaluate the correlation between functional eye outcome and retinal structural changes assessed by optical coherence tomography.

METHODS

The records of 32 patients with MOG-IgG-associated ON who underwent ophthalmological examination at least 12 months after ON onset were reviewed. Degree of VF disability was determined by mean deviation (MD).

RESULTS

At final assessment (median, 35 months), 4.2% of 48 affected eyes (AE) had VA ⩽ 0.1, 40% had abnormal MD, and among AE with final VA ⩾ 1.0, 31% had mild to moderate damage. Thinning of the inner retinal layers was significantly correlated with MD impairment. Analysis demonstrated a threshold of pRNFL thickness (50 µm), below which MD was significantly worse (mean, -2.27 dB vs -17.72 dB; p = 0.0003). ON relapse was significantly associated with poor visual outcome assessed by MD.

CONCLUSION

Functional impairment measured with VF is not rare, and MD assessment better reflects actual structural damage.

Visualizing the Central Nervous System: Imaging Tools for Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are autoimmune central nervous system conditions with increasing incidence and prevalence. While MS is the most frequent inflammatory CNS disorder in young adults, NMOSD is a rare disease, that is pathogenetically distinct from MS, and accounts for approximately 1% of demyelinating disorders, with the relative proportion within the demyelinating CNS diseases varying widely among different races and regions. Most immunomodulatory drugs used in MS are inefficacious or even harmful in NMOSD, emphasizing the need for a timely and accurate diagnosis and distinction from MS. Despite distinct immunopathology and differences in disease course and severity there might be considerable overlap in clinical and imaging findings, posing a diagnostic challenge for managing neurologists. Differential diagnosis is facilitated by positive serology for AQP4-antibodies (AQP4-ab) in NMOSD, but might be difficult in seronegative cases. Imaging of the brain, optic nerve, retina and spinal cord is of paramount importance when managing patients with autoimmune CNS conditions. Once a diagnosis has been established, imaging techniques are often deployed at regular intervals over the disease course as surrogate measures for disease activity and progression and to surveil treatment effects. While the application of some imaging modalities for monitoring of disease course was established decades ago in MS, the situation is unclear in NMOSD where work on longitudinal imaging findings and their association with clinical disability is scant. Moreover, as long-term disability is mostly attack-related in NMOSD and does not stem from insidious progression as in MS, regular follow-up imaging might not be useful in the absence of clinical events. However, with accumulating evidence for covert tissue alteration in NMOSD and with the advent of approved immunotherapies the role of imaging in the management of NMOSD may be reconsidered. By contrast, MS management still faces the challenge of implementing imaging techniques that are capable of monitoring progressive tissue loss in clinical trials and cohort studies into treatment algorithms for individual patients. This article reviews the current status of imaging research in MS and NMOSD with an emphasis on emerging modalities that have the potential to be implemented in clinical practice.

Unfavorable Structural and Functional Outcomes in Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis

BACKGROUND

Recurrent optic neuritis (rON) associated with myelin oligodendrocyte glycoprotein (MOG)-specific antibodies has been initially reported to show a better clinical outcome than aquaporin-4 (AQP4)-seropositive ON in neuromyelitis optica spectrum disorder (NMOSD). Here, we characterize clinical and neuroimaging findings in severe cases of MOG antibody-positive and AQP4 antibody-negative bilateral rON.

METHODS

Three male adults with rON (ages 18, 44, and 63 years) were evaluated with optical coherence tomography (OCT), MRI, cerebrospinal fluid (CSF), and serological studies.

RESULTS

All patients experienced >7 relapses of ON with severe reduction of visual acuity and partial response to steroid treatment. Optic nerves were affected bilaterally, although unilateral relapses were more frequent than simultaneous bilateral recurrences. Patients were MOG-seropositive but repeatedly tested negative for AQP4 antibodies. OCT showed severe thinning of the peripapillary retinal nerve fiber layer. On MRI, contrast-enhancing lesions extended over more than half the length of the optic nerve. CSF analyses during ON episodes were normal. Severe visual deficits accumulated over time in 2 of 3 patients, despite immunosuppressive therapy.

CONCLUSIONS

MOG-seropositive and AQP4-seronegative rON may be associated with an aggressive disease course and poor functional and structural outcomes. In contrast to previous reports, the severity and pattern of retinal and optic nerve damage closely resembled phenotypes commonly observed in AQP4-seropositive rON without fulfilling current diagnostic criteria for NMOSD.

Myelin oligodendrocyte glycoprotein antibodies in neurological disease

Anti-myelin oligodendrocyte glycoprotein (MOG) antibodies (MOG-Abs) were first detected by immunoblot and enzyme-linked immunosorbent assay nearly 30 years ago, but their association with multiple sclerosis (MS) was not specific. Use of cell-based assays with native MOG as the substrate enabled identification of a group of MOG-Ab-positive patients with demyelinating phenotypes. Initially, MOG-Abs were reported in children with acute disseminated encephalomyelitis (ADEM). Further studies identified MOG-Abs in adults and children with ADEM, seizures, encephalitis, anti-aquaporin-4-antibody (AQP4-Ab)-seronegative neuromyelitis optica spectrum disorder (NMOSD) and related syndromes (optic neuritis, myelitis and brainstem encephalitis), but rarely in MS. This shift in our understanding of the diagnostic assays has re-invigorated the examination of MOG-Abs and their role in autoimmune and demyelinating disorders of the CNS. The clinical phenotypes, disease courses and responses to treatment that are associated with MOG-Abs are currently being defined. MOG-Ab-associated disease is different to AQP4-Ab-positive NMOSD and MS. This Review provides an overview of the current knowledge of MOG, the metrics of MOG-Ab assays and the clinical associations identified. We collate the data on antibody pathogenicity and the mechanisms that are thought to underlie this. We also highlight differences between MOG-Ab-associated disease, NMOSD and MS, and describe our current understanding on how best to treat MOG-Ab-associated disease.

Nanoimmunosensor based on atomic force spectroscopy to detect anti-myelin basic protein related to early-stage multiple sclerosis

Multiple Sclerosis (MS) is a chronic inflammatory disorder in the central nervous system for which biomarkers for diagnosis still remain unknown. One potential biomarker is the myelin basic protein. Here, a nanoimmunosensor based on atomic force spectroscopy (AFS) successfully detected autoantibodies against the MBP_85-99 peptide from myelin basic protein. The nanoimmunosensor consisted of an atomic force microscope tip functionalization with MBP_85-99 peptide, which was made to interact with a mica surface coated either with a layer of anti-MBP_85-99 (positive control) or samples of cerebrospinal fluid (CSF) from five multiple sclerosis (MS) patients at different stages of the disease and five non-MS subjects. The adhesion forces obtained from AFS pointed to a high concentration of anti-MBP_85-99 for the two patients at early stages of relapsing-remitting multiple sclerosis (RRMS), which were indistinguishable from the positive control. In contrast, considerably lower adhesion forces were measured for all the other eight subjects, including three MS patients with longer history of the disease and under treatment, without episodes of acute MS activity. We have also shown that the average adhesion force between MBP_85-99 and anti-MBP_85-99 is compatible with the value estimated using steered molecular dynamics. Though further tests will be required with a larger cohort of patients, the present results indicate that the nanoimmunosensor may be a simple tool to detect early-stage MS patients and be useful to understand the molecular mechanisms behind MS.

Retinal correlates of neurological disorders

Considering the retina as an extension of the brain provides a platform from which to study diseases of the nervous system. Taking advantage of the clear optical media of the eye and ever-increasing resolution of modern imaging techniques, retinal morphology can now be visualized at a cellular level in vivo. This has provided a multitude of possible biomarkers and investigative surrogates that may be used to identify, monitor and study diseases until now limited to the brain. In many neurodegenerative conditions, early diagnosis is often very challenging due to the lack of tests with high sensitivity and specificity, but, once made, opens the door to patients accessing the correct treatment that can potentially improve functional outcomes. Using retinal biomarkers in vivo as an additional diagnostic tool may help overcome the need for invasive tests and histological specimens, and offers the opportunity to longitudinally monitor individuals over time. This review aims to summarise retinal biomarkers associated with a range of neurological conditions including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and prion diseases from a clinical perspective. By comparing their similarities and differences according to primary pathological processes, we hope to show how retinal correlates can aid clinical decisions, and accelerate the study of this rapidly developing area of research.

Aquaporin-4 and myelin oligodendrocyte glycoprotein antibodies in immune-mediated optic neuritis at long-term follow-up

OBJECTIVES

To re-evaluate serum samples from our 2007 cohort of patients with single-episode isolated ON (SION), recurrent isolated ON (RION), chronic relapsing inflammatory optic neuropathy (CRION), multiple sclerosis-associated ON (MSON) and neuromyelitis optica (NMO).

METHODS

We re-screened 103/114 patients with available serum on live cell-based assays (CBA) for aquaporin-4 (AQP4)-M23-IgG and myelin-oligodendrocyte glycoprotein (MOG)-α1-IgG. Further testing included oligoclonal bands, serum levels of glial fibrillar acidic and neurofilament proteins and S100B. We show the impact of updated serology on these patients.

RESULTS

Reanalysis of our original cohort revealed that AQP4-IgG seropositivity increased from 56% to 75% for NMO, 5% to 22% for CRION, 6% to 7% for RION, 0% to 7% for MSON and 5% to 6% for SION. MOG-IgG1 was identified in 25% of RION, 25% of CRION, 10% of SION, 0% of MSON and 0% of NMO. As a result, patients have been reclassified incorporating their autoantibody status. Presenting visual acuity was significantly worse in patients who were AQP4-IgG seropositive (p=0.034), but there was no relationship between antibody seropositivity and either ON relapse rate or visual acuity outcome.

CONCLUSIONS

The number of patients with seronegative CRION and RION has decreased due to improved detection of autoantibodies over the past decade. It remains essential that the clinical phenotype guides both antibody testing and clinical management. Careful monitoring of the disease course is key when considering whether to treat with prophylactic immune suppression.

Aquaporin-4 IgG seropositivity is associated with worse visual outcomes after optic neuritis than MOG-IgG seropositivity and multiple sclerosis, independent of macular ganglion cell layer thinning

BACKGROUND

Comparative studies of characteristics of optic neuritis (ON) associated with myelin oligodendrocyte glycoprotein-IgG (MOG-ON) and aquaporin-4-IgG (AQP4-ON) seropositivity are limited.

OBJECTIVE

To compare visual and optical coherence tomography (OCT) measures following AQP4-ON, MOG-ON, and multiple sclerosis associated ON (MS-ON).

METHODS

In this cross-sectional study, 48 AQP4-ON, 16 MOG-ON, 40 MS-ON, and 31 healthy control participants underwent monocular letter-acuity assessment and spectral-domain OCT. Eyes with a history of ON >3 months prior to evaluation were analyzed.

RESULTS

AQP4-ON eyes exhibited worse high-contrast letter acuity (HCLA) compared to MOG-ON (-22.3 ± 3.9 letters; p < 0.001) and MS-ON eyes (-21.7 ± 4.0 letters; p < 0.001). Macular ganglion cell + inner plexiform layer (GCIPL) thickness was lower, as compared to MS-ON, in AQP4-ON (-9.1 ± 2.0 µm; p < 0.001) and MOG-ON (-7.6 ± 2.2 µm; p = 0.001) eyes. Lower GCIPL thickness was associated with worse HCLA in AQP4-ON (-16.5 ± 1.5 letters per 10 µm decrease; p < 0.001) and MS-ON eyes (-8.5 ± 2.3 letters per 10 µm decrease; p < 0.001), but not in MOG-ON eyes (-5.2 ± 3.8 letters per 10 µm decrease; p = 0.17), and these relationships differed between the AQP4-ON and other ON groups (p < 0.01 for interaction).

CONCLUSION

AQP4-IgG seropositivity is associated with worse visual outcomes after ON compared with MOG-ON and MS-ON, even with similar severity of macular GCIPL thinning.

Optical coherence tomography in myelin-oligodendrocyte-glycoprotein antibody-seropositive patients: a longitudinal study

Background

Serum antibodies against myelin-oligodendrocyte-glycoprotein (MOG-IgG) are detectable in a proportion of patients with acute or relapsing neuroinflammation. It is unclear, if neuro-axonal damage occurs only in an attack-dependent manner or also progressively. Therefore, this study aimed to investigate longitudinally intra-retinal layer changes in eyes without new optic neuritis (ON) in MOG-IgG-seropositive patients.

Methods

We included 38 eyes of 24 patients without ON during follow-up (F/U) [median years (IQR)] 1.9 (1.0–2.2) and 56 eyes of 28 age- and sex-matched healthy controls (HC). The patient group’s eyes included 18 eyes without (Eye^ON-) and 20 eyes with history of ON (Eye^ON+). Using spectral domain optical coherence tomography (OCT), we acquired peripapillary retinal nerve fiber layer thickness (pRNFL) and volumes of combined ganglion cell and inner plexiform layer (GCIP), inner nuclear layer (INL), and macular volume (MV). High-contrast visual acuity (VA) was assessed at baseline.

Results

At baseline in Eye^ON-, pRNFL (94.3 ± 15.9 μm, p = 0.36), INL (0.26 ± 0.03 mm³, p = 0.11), and MV (2.34 ± 0.11 mm³, p = 0.29) were not reduced compared to HC; GCIP showed thinning (0.57 ± 0.07 mm³; p = 0.008), and VA was reduced (logMAR 0.05 ± 0.15 vs. − 0.09 ± 0.14, p = 0.008) in comparison to HC. Longitudinally, we observed pRNFL thinning in models including all patient eyes (annual reduction − 2.20 ± 4.29 μm vs. − 0.35 ± 1.17 μm, p = 0.009) in comparison to HC. Twelve Eye^ON- with other than ipsilateral ON attacks ≤ 6 months before baseline showed thicker pRNFL at baseline and more severe pRNFL thinning in comparison to 6 Eye^ON- without other clinical relapses.

Conclusions

We observed pRNFL thinning in patients with MOG-IgG during F/U, which was not accompanied by progressive GCIP reduction. This effect could be caused by a small number of Eye^ON- with other than ipsilateral ON attacks within 6 months before baseline. One possible interpretation could be a reduction of the swelling, which could mean that MOG-IgG patients show immune-related swelling in the CNS also outside of an attack’s target area.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1521-5) contains supplementary material, which is available to authorized users.

Optical coherence tomography as a means to characterize visual pathway involvement in multiple sclerosis

PURPOSE OF REVIEW

Optical coherence tomography (OCT) is a noninvasive in-vivo imaging tool that enables the quantification of the various retinal layer thicknesses. Given the frequent involvement of the visual pathway in multiple sclerosis, OCT has become an important tool in clinical practice, research and clinical trials. In this review, the role of OCT as a means to investigate visual pathway damage in multiple sclerosis is discussed.

RECENT FINDINGS

Evidence from recent OCT studies suggests that the peripapillary retinal nerve fibre layer (pRNFL) appears to be an ideal marker of axonal integrity, whereas the macular ganglion cell and inner plexiform layer (GCIP) thickness enables early detection of neuronal degeneration in multiple sclerosis. The thickness of the macular inner nuclear layer (INL) has been suggested as a biomarker for inflammatory disease activity and treatment response in multiple sclerosis. OCT parameters may also be used as an outcome measure in clinical trials evaluating the neuroprotective or regenerative potential of new treatments.

SUMMARY

OCT provides insights into multiple sclerosis beyond the visual pathway. It is capable of quantifying the major pathological hallmarks of the disease, specifically inflammation and neuroaxonal degeneration. OCT, therefore, has the potential to become another mainstay in the monitoring of multiple sclerosis patients.

Different Characteristics of Aquaporin-4 and Myelin Oligodendrocyte Glycoprotein Antibody-Seropositive Male Optic Neuritis in China

Purpose

To describe different clinical characteristics and prognosis of optic neuritis (ON) in male patients with seropositive aquaporin-4 antibody (AQP4-Ab) or myelin oligodendrocyte glycoprotein antibody (MOG-Ab) in China.

Method

Males with ON were recruited from the Neuro-ophthalmology Department of the Chinese People's Liberation Army, General Hospital from January 2016 to February 2018. They were assigned to two groups based on antibodies status: MOG-Ab-seropositive ON (MOG-ON) and aquaporin-4 Ab-seropositive ON (AQP4-ON).

Results

Seventy-six male patients were assessed, including 44 MOG-ON (57.9%) and 32 AQP4-ON (42.1%). The MOG-ON patients were significantly younger at onset compared to the AQP4-ON group (p < 0.001). Frequencies of optic disc swelling, presence of abnormal autoimmune antibodies, and elevated levels of CSF IgG were significantly higher in the AQP4-ON group than the MOG-ON group (p=0.040, p=0.016, and p=0.10, respectively). At the final visit, 85.3% of MOG-ON eyes had increased visual acuity (≥0.5) compared to 35.1% of AQP4-ON eyes (p < 0.001). The ratio of this steroid-dependent condition is higher in MOG-ON patients than the AQP4-ON group (p < 0.001). The ratio of conversion to NMO is higher in the AQP4-ON group than the MOG-ON group, with more AQP4-ON patients developing NMO by the follow-up (p=0.012). MOG-ON patients had thicker average peripapillary retinal nerve fiber layers and macular ganglion cell-inner plexiform than AQP4-ON patients (p=0.008 and p=0.012, respectively). Orbital MRI revealed more AQP4-ON patients had chiasmal involvement than MOG-ON patients (p < 0.001).

Conclusion

Male MOG-ON patients had different clinical features including earlier age of onset, higher optic disc swelling ratio, better visual acuity recovery, thicker peripapillary retinal nerve fiber and macular ganglion cell-inner plexiform layers, and less chiasmal involvement than male AQP4-ON patients. Serum antibody may be a potential biomarker for determining visual prognosis in male ON.

[Optical coherence tomography in neuromyelitis optica spectrum disorders]

Neuromyelitis optica spectrum disorders (NMOSD) are mostly relapsing inflammatory conditions of the central nervous system (CNS). In 55% of the cases of NMOSD optic neuritis (ON) is the most frequent first manifestation and can cause severe damage to the afferent visual system and the retina with resultant severe visual impairment. In recent years, investigations of the retina as part of the CNS by optical coherence tomography (OCT) has been shown to be a valid and efficient method for diagnostics and evaluation of the disease course in NMOSD. In addition, OCT not only shows severe damage of the afferent visual system due to multiple bouts of ON but also reveals NMOSD-specific intraretinal pathologies. The latter could be just as important for future differential diagnostics as for the evaluation of potential therapeutic targets. This article briefly reviews the principles of the OCT technique and describes its relevance for the diagnostics and assessment of disease course in NMOSD.

Mechanisms for lesion localization in neuromyelitis optica spectrum disorders

Purpose of review

Neuromyelitis optica spectrum disorders (NMOSD) are severe inflammatory diseases of the central nervous system (CNS), with the presence of aquaporin 4 (AQP4)-specific serum antibodies in the vast majority of patients, and with the presence of myelin oligodendrocyte glycoprotein (MOG)-specific antibodies in approximately 40% of all AQP4-antibody negative NMOSD patients. Despite differences in antigen recognition, the preferred sites of lesions are similar in both groups of patients: They localize to the spinal cord and to the anterior visual pathway including retina, optic nerves, chiasm, and optic tracts, and – to lesser extent – also to certain predilection sites in the brain.

Recent findings

The involvement of T cells in the formation of NMOSD lesions has been challenged for quite some time. However, several recent findings demonstrate the key role of T cells for lesion formation and localization. Studies on the evolution of lesions in the spinal cord of NMOSD patients revealed a striking similarity of early NMOSD lesions with those observed in corresponding T-cell-induced animal models, both in lesion formation and in lesion localization. Studies on retinal abnormalities in NMOSD patients and corresponding animals revealed the importance of T cells for the very early stages of retinal lesions which eventually culminate in damage to Müller cells and to the retinal nerve fiber layer. Finally, a study on cerebrospinal fluid (CSF) barrier pathology demonstrated that NMOSD immunopathology extends beyond perivascular astrocytic foot processes to include the pia, the ependyma, and the choroid plexus, and that diffusion of antibodies from the CSF could further influence lesion formation in NMOSD patients.

Summary

The pathological changes observed in AQP4-antibody positive and MOG-antibody positive NMOSD patients are strikingly similar to those found in corresponding animal models, and many mechanisms which determine lesion localization in experimental animals seem to closely reflect the human situation.

Novel uses of retinal imaging with optical coherence tomography in multiple sclerosis

Introduction: Multiple Sclerosis (MS) is the most common chronic autoimmune neuroinflammatory condition in young adults. It is often accompanied by optic neuritis (ON) and retinal neuro-axonal damage causing visual disturbances. Optical coherence tomography (OCT) is a sensitive non-invasive method for quantifying intraretinal layer volumes. Recently, OCT not only showed to be a reliable marker for ON-associated damage, but also proved its high prognostic value for functional outcome and disability accrual in patients with MS. Consequently, OCT is discussed as a potential marker for monitoring disease severity and therapeutic response in individual patients. Areas covered: This article summarizes our current understanding of structural retinal changes in MS and describes the future potential of OCT for differential diagnosis, monitoring of the disease course and for clinical trials. Expert commentary: Today, OCT is used in clinical practice in specialized MS centers. Standardized parameters across devices are urgently needed for supporting clinical utility. Novel parameters are desirable to increase sensitivity and specificity in terms of MS.

Preclinical stress originates in the rat optic nerve head during development of autoimmune optic neuritis

Optic neuritis is a common manifestation of multiple sclerosis, an inflammatory demyelinating disease of the CNS. Although it is the presenting symptom in many cases, the initial events are currently unknown. However, in the earliest stages of autoimmune optic neuritis in rats, pathological changes are already apparent such as microglial activation and disturbances in myelin ultrastructure of the optic nerves. αB‐crystallin is a heat‐shock protein induced in cells undergoing cellular stress and has been reported to be up‐regulated in both multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis. Therefore, we wished to investigate the timing and localization of its expression in autoimmune optic neuritis. Although loss of oligodendrocytes was not observed until the later disease stages accompanying immune cell infiltration and demyelination, an increase in oligodendrocyte αB‐crystallin was observed during the preclinical stages. This was most pronounced within the optic nerve head and was associated with areas of IgG deposition. Since treatment of isolated oligodendrocytes with sera from myelin oligodendrocyte glycoprotein (MOG)‐immunized animals induced an increase in αB‐crystallin expression, as did passive transfer of sera from MOG‐immunized animals to unimmunized recipients, we propose that the partially permeable blood–brain barrier of the optic nerve head may present an opportunity for blood‐borne components such as anti‐MOG antibodies to come into contact with oligodendrocytes as one of the earliest events in disease development.