We have witnessed major successes in the development of effective immunomodulatory therapies capable of reducing adaptive immune-mediated myelin damage in MS over the last 30 years. However, until it is possible to prevent MS or initiate treatment before it has already caused lesions there is a need to repair myelin damage to prevent further axonal loss. The past decade has brought remarkable advances in our understanding of oligodendrocyte biology and the related search for remyelinating therapies in humans. In this review, we first outline the basic biology of central nervous system myelin and remyelination, including a discussion of the major identified pathways and targets that might help yield CNS remyelinating drugs. In conjunction, we provide an overview of techniques that have helped identify compounds capable of promoting oligodendrocyte precursor cell differentiation and myelination. This includes the methods for both initial in vitro screening and subsequent in vivo confirmation of the target. We then review methods proposed to quantify human remyelination in vivo, including visual evoked potentials and putative imaging modalities. As the remyelination era approaches, with the announcement of the first positive trial in remyelination, we are now tasked with answering new questions regarding patient-specific factors (e.g., age) that may influence the extent and optimal therapeutic window for remyelination.

Objective

To determine whether fingolimod, an oral sphingosine-1-phosphate receptor modulator approved for treatment of multiple sclerosis (MS), generally leads to increased retinal tissue volume.

Methods

In this longitudinal observational study, we compared changes in macular volume on spectral-domain optical coherence tomography (OCT) between consecutive patients with MS who initiated fingolimod and a matched reference cohort of patients with MS never exposed to the drug. The primary reference cohort was matched based on time interval between OCT examinations. A secondary reference cohort was matched based on age and disease duration. Change in macular volume within each group was analyzed using the paired t test. Change in macular volume between groups was examined using multiple linear regression.

Results

Macular volume increased by a mean of 0.025 mm3 (95% confidence interval [CI] +0.017 to +0.033, p < 0.001) in the 30 patients with MS who initiated fingolimod over a mean follow-up time of 5 months (SD 3). Macular volume did not significantly change over a mean follow-up time of 6 months (SD 4) in a comparison group of 30 patients with MS never treated with fingolimod (mean change of -0.003 mm3, 95% CI -0.009 to +0.004, p = 0.47). Overall, 74% of eyes in the fingolimod-treated group exhibited an increase in macular volume vs. 37% of eyes in the comparison group.

Conclusion

Initiation of fingolimod in MS is associated with a modest, relatively rapid increase in macular volume.

Importance

Brain biopsy specimens that exhibit encephalitis without specific histopathologic features pose a diagnostic challenge to neuropathologists and neurologists. Such cases are generally referred to pathologically as encephalitis, not otherwise specified (ENOS). A systematic approach to diagnostic evaluation in such patients is challenging, and currently there is no generally accepted algorithm.

Objective

To examine ultimate diagnostic outcomes in patients with ENOS diagnosed by brain biopsy.

Design, setting, and participants

This retrospective case series at the University of California, San Francisco, Medical Center, a tertiary care urban neurosciences center, studied patients with encephalitis diagnosed by brain biopsy from January 1, 1983, through December 31, 2011.

Exposures

Brain biopsy.

Main outcomes and measures

Clinical and neuropathologic diagnosis.

Results

Among 58 patients who met the inclusion criteria for the study, the original pathologic diagnosis was ENOS in 49 patients (84%). The median age was 40 years (interquartile range, 27-53 years), 35 patients were male, and 13 had known human immunodeficiency virus or AIDS. Median time from onset of symptoms to brain biopsy was 66 days (interquartile range, 18-135 days). For the 29 patients in whom material for pathologic analysis was still available, additional neuropathologic review led to a more specific categorization in 10 (34%). Clinical detail and follow-up information was available for 42 patients, and a specific diagnosis was reached with the help of ancillary testing and/or clinical follow-up in 12 patients. Despite a comprehensive neuropathologic review with additional studies and information, 27 patients still had to be classified in the ENOS category at the end of the study.

Conclusions and relevance

ENOS is the most common initial type of encephalitis diagnosed by brain biopsy. In such patients, it may be worth having the biopsy materials reviewed again in a comprehensive fashion by a neuropathologist because additional review led to a more specific categorization in one-third of our cases. Ancillary testing, clinical correlation, and clinical follow-up establish more specific diagnoses in some patients. ENOS still remains a diagnostic challenge after all these efforts in many cases. Current algorithms are of limited value. More advanced methods and better diagnostic algorithms are needed to characterize these patients.

Aquaporin-4 (AQP4)-specific antibodies are instrumental in promoting central nervous system (CNS) tissue injury in neuromyelitis optica (NMO), yet evidence indicates that AQP4-specific T cells also have a pivotal role in NMO pathogenesis. Although considerable effort has been devoted to creation of animal models to study how AQP4-specific T cells and antibodies may cooperate in development of both clinical and histologic opticospinal inflammatory disease, the initial attempts were unsuccessful. Recently, it was discovered that T cells from AQP4-deficient (AQP4-/-) mice recognize distinct AQP4 epitopes that were not identified previously in wild-type (WT) mice, and that donor Th17 cells from AQP4-/- mice that target those novel epitopes could cause paralysis and visual system injury associated with opticospinal inflammation in WT recipient mice. These observations indicate that the pathogenic AQP4-specific T cell repertoire is normally controlled by negative selection. Here, we describe the advances leading to development of an animal model for aquaporin-targeted CNS autoimmunity (ATCA). This new model provides a foundation to investigate immune mechanisms that may participate in NMO pathogenesis. It should also permit preclinical testing of agents considered for treatment of NMO.

Objective

To describe the routine use of telemedicine-enabled neurologic care in an academic outpatient MS and neuroimmunology clinic and quantify its role in reducing patient burden.

Methods

Between January 2017 and December 2017, we surveyed patients and MS neurologists after 50 consecutive routinely scheduled televideo visits and a convenience sample of 100 in-clinic visits. Summary statistics were calculated and comparisons performed.

Results

Overall, 98% televideo participants found the technology easy to use, and only 17% believed that an in-person examination would have more effectively addressed their needs for the visit. MS neurologists reported achieving their clinical goals in 47/48 (98%) of televideo visits and an adequate physical examination with 2 exceptions (possible cauda equina syndrome and visual field loss). Three emergency department referrals were avoided due to televideo availability. Telemedicine reduced travel burden, including a mean (±SD) travel distance of 160 (±196) miles and avoiding overnight lodging and air travel. Telemedicine also reduced indirect costs, including time off work (65% of employed patients) and caregiver burden (30% avoided caregiver time off from work/obligations). Across 8 domains of provider interpersonal communication skills, telemedicine and in-clinic participants rated only 1 domain to be different (eye contact), and overall, 96% of in-clinic and 100% of telemedicine participants agreed/strongly agreed that their clinical goals had been met.

Conclusions

When incorporated as part of the continuum of MS/neuroimmunology care, clinic to in-home telemedicine reduces travel and caregiver burden and enables efficient, convenient, and effective follow-up.

Background

In recent years, the ability of conventional magnetic resonance imaging (MRI), including T₁ contrast-enhanced (CE) MRI, to monitor high-efficacy therapies and predict long-term disability in multiple sclerosis (MS) has been challenged. Therefore, non-invasive methods to improve MS lesions detection and monitor therapy response are needed.

Methods

We studied the combined cuprizone and experimental autoimmune encephalomyelitis (CPZ-EAE) mouse model of MS, which presents inflammatory-mediated demyelinated lesions in the central nervous system as commonly seen in MS patients. Using hyperpolarized ¹³C MR spectroscopy (MRS) metabolic imaging, we measured cerebral metabolic fluxes in control, CPZ-EAE and CPZ-EAE mice treated with two clinically-relevant therapies, namely fingolimod and dimethyl fumarate. We also acquired conventional T₁ CE MRI to detect active lesions, and performed ex vivo measurements of enzyme activities and immunofluorescence analyses of brain tissue. Last, we evaluated associations between imaging and ex vivo parameters.

Results

We show that hyperpolarized [1-¹³C]pyruvate conversion to lactate is increased in the brain of untreated CPZ-EAE mice when compared to the control, reflecting immune cell activation. We further demonstrate that this metabolic conversion is significantly decreased in response to the two treatments. This reduction can be explained by increased pyruvate dehydrogenase activity and a decrease in immune cells. Importantly, we show that hyperpolarized ¹³C MRS detects dimethyl fumarate therapy, whereas conventional T₁ CE MRI cannot.

Conclusions

In conclusion, hyperpolarized MRS metabolic imaging of [1-¹³C]pyruvate detects immunological responses to disease-modifying therapies in MS. This technique is complementary to conventional MRI and provides unique information on neuroinflammation and its modulation.

Background

To determine whether retinal axonal loss is detectable in patients with a clinically isolated syndrome (CIS), a first clinical demyelinating attack suggestive of multiple sclerosis (MS), and examine patterns of retinal axonal loss across MS disease subtypes.

Methodology/principal findings

Spectral-domain Optical Coherence Tomography was performed in 541 patients with MS, including 45 with high-risk CIS, 403 with relapsing-remitting (RR)MS, 60 with secondary-progressive (SP)MS and 33 with primary-progressive (PP)MS, and 53 unaffected controls. Differences in retinal nerve fiber layer (RNFL) thickness and macular volume were analyzed using multiple linear regression and associations with age and disease duration were examined in a cross-sectional analysis. In eyes without a clinical history of optic neuritis (designated as "eyes without optic neuritis"), the total and temporal peripapillary RNFL was thinner in CIS patients compared to controls (temporal RNFL by -5.4 µm [95% CI -0.9 to--9.9 µm, p = 0.02] adjusting for age and sex). The total (p = 0.01) and temporal (p = 0.03) RNFL was also thinner in CIS patients with clinical disease for less than 1 year compared to controls. In eyes without optic neuritis, total and temporal RNFL thickness was nearly identical between primary and secondary progressive MS, but total macular volume was slightly lower in the primary progressive group (p<0.05).

Conclusions/significance

Retinal axonal loss is increasingly prominent in more advanced stages of disease--progressive MS>RRMS>CIS--with proportionally greater thinning in eyes previously affected by clinically evident optic neuritis. Retinal axonal loss begins early in the course of MS. In the absence of clinically evident optic neuritis, RNFL thinning is nearly identical between progressive MS subtypes.

Background and objectives

Patients with multiple sclerosis (MS) transition from oral sphingosine-1-receptor (S1P) modulators to anti-CD20 therapies for several circumstances. Optimal timing of this transition is uncertain, given competing concerns of rebound disease activity and ensuring immune reconstitution. The objective of this study was to evaluate the relationship between inflammatory activity and the transition period from fingolimod to anti-CD20 therapies in a real-world MS cohort.

Methods

Medical records were reviewed for all patients at our center transitioning from fingolimod to rituximab or ocrelizumab between 2010 and October 2020. Time periods reviewed were the following: before fingolimod discontinuation, interval between fingolimod and anti-CD20 treatments, and after the first anti-CD20 infusion. The primary outcome was clinical relapses; MRI activity, time to absolute lymphocyte count (ALC) recovery, and infections were secondary. Clinical and demographic factors significant in univariable analyses were included in multivariable analyses.

Results

Transition data were available for 108 patients (68.5% women, 68.5% relapsing-remitting MS, mean age 44.6 years). The median (interquartile range) interval between fingolimod and anti-CD20 therapy was 28 (1-115.2) days. Six of 51 patients (11.8%) with intervals >1 month and 0/57 patients with shorter intervals experienced a relapse (MRI confirmed) within 6 months of fingolimod discontinuation. In the year following anti-CD20 initiation, 4/108 patients (3.7%) experienced a relapse (median 214.5 days after infusion). An additional 7% of those undergoing contrast-enhanced MRIs developed Gd+ lesions. ALC normalized following treatment switch in 89/92; the interval between treatments was unrelated to ALC recovery or infection.

Discussion

Delaying anti-CD20 start to monitor ALC after S1P modulator discontinuation may not be necessary and could increase rebound risk. ALC monitoring could instead occur after a rapid switch to anti-CD20 treatment.

A significant unmet need for patients with multiple sclerosis (MS) is the lack of U.S. Food and Drug Administration (FDA)-approved remyelinating therapies. We have identified a compelling remyelinating agent, bazedoxifene (BZA), a European Medicines Agency (EMA)-approved (and FDA-approved in combination with conjugated estrogens) selective estrogen receptor (ER) modulator (SERM) that could move quickly from bench to bedside. This therapy stands out as a tolerable alternative to previously identified remyelinating agents and other candidates within this family. Using an unbiased high-throughput screen, with subsequent validation in both murine and human oligodendrocyte precursor cells (OPCs) and coculture systems, we find that BZA enhances differentiation of OPCs into functional oligodendrocytes. Using an in vivo murine model of focal demyelination, we find that BZA enhances OPC differentiation and remyelination. Of critical importance, we find that BZA acts independently of its presumed target, the ER, in both in vitro and in vivo systems. Using a massive computational data integration approach, we independently identify six possible candidate targets through which SERMs may mediate their effect on remyelination. Of particular interest, we identify EBP (encoding 3β-hydroxysteroid-Δ8,Δ7-isomerase), a key enzyme in the cholesterol biosynthesis pathway, which was previously implicated as a target for remyelination. These findings provide valuable insights into the implications for SERMs in remyelination for MS and hormonal research at large.SIGNIFICANCE STATEMENT Therapeutics targeted at remyelination failure, which results in axonal degeneration and ultimately disease progression, represent a large unmet need in the multiple sclerosis (MS) population. Here, we have validated a tolerable European Medicines Agency-approved (U.S. Food and Drug Administration-approved in combination with conjugated estrogens) selective estrogen receptor (ER) modulator (SERM), bazedoxifene (BZA), as a potent agent of oligodendrocyte precursor cell (OPC) differentiation and remyelination. SERMs, which were developed as nuclear ER-α and ER-β agonists/antagonists, have previously been implicated in remyelination and neuroprotection, following a heavy focus on estrogens with underwhelming and conflicting results. We show that nuclear ERs are not required for SERMs to mediate their potent effects on OPC differentiation and remyelination in vivo and highlight EBP, an enzyme in the cholesterol biosynthesis pathway that could potentially act as a target for SERMs.

Point mutations at m.8993T>C and m.8993T>G of the mtDNA ATPase 6 gene cause the neurogenic weakness, ataxia and retinitis pigmentosa (NARP) syndrome, a mitochondrial disorder characterized by retinal, central and peripheral neurodegeneration. We performed detailed neurological, neuropsychological and ophthalmological phenotyping of a mother and four daughters with NARP syndrome from the mtDNA m.8993T>C ATPase 6 mutation, including 3-T brain MRI, spectral domain optical coherence tomography (SD-OCT), adaptive optics scanning laser ophthalmoscopy (AOSLO), electromyography and nerve conduction studies (EMG-NCS) and formal neuropsychological testing. The degree of mutant heteroplasmy for the m.8993T>C mutation was evaluated by real-time allele refractory mutation system quantitative PCR of mtDNA from hair bulbs (ectoderm) and blood leukocytes (mesoderm). There were marked phenotypic differences between family members, even between individuals with the greatest degrees of ectodermal and mesodermal heteroplasmy. 3-T MRI revealed cerebellar atrophy and cystic and cavitary T2 hyperintensities in the basal ganglia. SD-OCT demonstrated similarly heterogeneous areas of neuronal and axonal loss in inner and outer retinal layers. AOSLO showed increased cone spacing due to photoreceptor loss. EMG-NCS revealed varying degrees of length-dependent sensorimotor axonal polyneuropathy. On formal neuropsychological testing, there were varying deficits in processing speed, visual-spatial functioning and verbal fluency and high rates of severe depression. Many of these cognitive deficits likely localize to cerebellar and/or basal ganglia dysfunction. High-resolution retinal and brain imaging in NARP syndrome revealed analogous patterns of tissue injury characterized by heterogeneous areas of neuronal loss.