Clinical Correlation of Multiple Sclerosis Immunopathologic Subtypes

Determinants and Biomarkers of Progression Independent of Relapses in Multiple Sclerosis

Clinical, pathological, and imaging evidence in multiple sclerosis (MS) suggests that a smoldering inflammatory activity is present from the earliest stages of the disease and underlies the progression of disability, which proceeds relentlessly and independently of clinical and radiological relapses (PIRA). The complex system of pathological events driving "chronic" worsening is likely linked with the early accumulation of compartmentalized inflammation within the central nervous system as well as insufficient repair phenomena and mitochondrial failure. These mechanisms are partially lesion-independent and differ from those causing clinical relapses and the formation of new focal demyelinating lesions; they lead to neuroaxonal dysfunction and death, myelin loss, glia alterations, and finally, a neuronal network dysfunction outweighing central nervous system (CNS) compensatory mechanisms. This review aims to provide an overview of the state of the art of neuropathological, immunological, and imaging knowledge about the mechanisms underlying the smoldering disease activity, focusing on possible early biomarkers and their translation into clinical practice. ANN NEUROL 2024;96:1-20.

Differentiation of hemispheric white matter lesions in migraine and multiple sclerosis with similar radiological features using advanced MRI

Background and aim

White matter hyperintensities (WMHs), presented on T2-weighted or fluid-attenuated inversion recovery magnetic resonance imaging (MRI) sequences, are lesions in the human brain that can be observed in both migraine and multiple sclerosis (MS).

Methods

Seventeen migraine patients and 15 patients with relapsing-remitting multiple sclerosis with WMHs, and 17 healthy subjects age-and sex-matched to the migraine group were prospectively enrolled and underwent conventional and advanced MRI studies with diffusion-and perfusion-weighted imaging and single voxel proton magnetic resonance spectroscopy.

Results

In both disease groups, elevated T2 relaxation time, apparent diffusion coefficient (ADC) values, and decreased N-acetyl-aspartate levels were found in the intralesional white matter compared to the contralateral normal-appearing white matter (NAWM), while there was no difference between the hemispheres of the control subjects. Migraine patients had the lowest intralesional creatine + phosphocreatine and myo-inositol (mI) values among the three groups, while patients with MS showed the highest intralesional T1 and T2 relaxation times, ADC, and mI values. In the contralateral NAWM, the same trend with mI changes was observed in migraineurs and MS patients. No differences in perfusion variables were observed in any groups.

Conclusion

Our multimodal study showed that tissue damage is detectable in both diseases. Despite the differences in various advanced MRI measures, with more severe injury detected in MS lesions, we could not clearly differentiate the two white matter lesion types.

High Levels of Perivascular Inflammation and Active Demyelinating Lesions at Time of Death Associated with Rapidly Progressive Multiple Sclerosis Disease Course: A Retrospective Postmortem Cohort Study

OBJECTIVE

Analysis of postmortem multiple sclerosis (MS) tissues combined with in vivo disease milestones suggests that whereas perivascular white matter infiltrates are associated with demyelinating activity in the initial stages, leptomeningeal immune cell infiltration, enriched in B cells, and associated cortical lesions contribute to disease progression. We systematically examine the association of inflammatory features and white matter demyelination at postmortem with clinical milestones.

METHODS

In 269 MS brains, 20 sites were examined using immunohistochemistry for active lesions (ALs) and perivenular inflammation (PVI). In a subset of 22, a detailed count of CD20+ B cells and CD3+ T cells in PVIs was performed.

RESULTS

ALs were detected in 22%, whereas high levels of PVI were detected in 52% of cases. ALs were present in 35% of cases with high levels of PVI. Shorter time from onset of progression to death was associated with increased prevalence and higher levels of PVI (both p < 0.0001). Shorter time from onset of progression to wheelchair use was associated with higher prevalence of ALs (odds ratio [OR] = 0.921, 95% confidence interval [CI] = 0.858-0.989, p = 0.0230) and higher level of PVI (OR = 0.932, 95% CI = 0.886-0.981, p = 0.0071). High levels of PVI were associated with meningeal inflammation and increased cortical demyelination and significantly higher levels of B lymphocytes within the PVI.

INTERPRETATION

ALs, a feature of early disease stage, persist up to death in a subgroup with high levels of PVI. These features link to a rapid progressive phase and higher levels of meningeal inflammation and B-cell infiltrates, supporting the hypothesis that chronic inflammation drives progression in MS. ANN NEUROL 2024;95:706-719.

Pathogenic role of autoantibodies at the ependyma in autoimmune disorders of the central nervous system

Ependymal cells make up the epithelial monolayer that lines the brain ventricles and the spinal cord central canal that are filled with cerebrospinal fluid. The ependyma has several functions, including regulating solute exchange between the cerebrospinal fluid and parenchyma, controlling microcirculation of cerebrospinal fluid via coordinated ciliary beating, and acting as a partial barrier. Dysregulation of these functions can lead to waste clearance impairment, cerebrospinal fluid accumulation, hydrocephalus, and more. A role for ependymal cells in a variety of neurological disorders has been proposed, including in neuromyelitis optica and multiple sclerosis, two autoimmune demyelinating diseases of the central nervous system, where periventricular damage is common. What is not known is the mechanisms behind how ependymal cells become dysregulated in these diseases. In neuromyelitis optica, it is well established that autoantibodies directed against Aquaporin-4 are drivers of disease, and it has been shown recently that these autoantibodies can drive ependymal cell dysregulation. We propose a similar mechanism is at play in multiple sclerosis, where autoantibodies targeting a glial cell protein called GlialCAM on ependymal cells are contributing to disease. GlialCAM shares high molecular similarities with the Epstein-Barr virus (EBV) protein EBNA1. EBV has recently been shown to be necessary for multiple sclerosis initiation, yet how EBV mediates pathogenesis, especially in the periventricular area, remains elusive. In this perspective article, we discuss how ependymal cells could be targeted by antibody-related autoimmune mechanisms in autoimmune demyelinating diseases and how this is implicated in ventricular/periventricular pathology.

Defining the natural history of tumefactive demyelination: A retrospective cohort of 257 patients

OBJECTIVE

To describe demographic, clinical, and radiographic features of tumefactive demyelination (TD) and identify factors associated with severe attacks and poor outcomes.

METHODS

Retrospective review of TD cases seen at Mayo Clinic, 1990-2021.

RESULTS

Of 257 patients with TD, 183/257 (71%) fulfilled the 2017 multiple sclerosis (MS) McDonald criteria at the last follow-up, 12/257 (5%) had myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), 0 had aquaporin-4-IgG seropositive neuromyelitis optic spectrum disorders (AQP4+ NMOSD), and 62/257 (24%) were cryptogenic. Onset before age 18 was present in 18/257 (7%). Female to male ratio was 1.3:1. Cerebrospinal fluid oligoclonal (CSF) bands were present in 95/153 (62%). TD was the first demyelinating attack in 176/257 (69%). At presentation, 59/126 (47%) fulfilled Barkhof criteria for dissemination in space, 59/100 (59%) had apparent diffusion coefficient (ADC) restriction, and 57/126 (45%) had mass effect. Despite aggressive clinical presentation at onset, 181/257 (70%) of patients remained fully ambulatory (Expanded Disability Status Scale [EDSS] ≤4) after a 3.0-year median follow-up duration. Severe initial attack-related disability (EDSS ≥4) was more common in patients with motor symptoms (81/143 vs. 35/106, p < 0.0001), encephalopathy (20/143 vs. 2/106, p < 0.0001) and ADC restriction on initial MRI (42/63 vs. 15/33, p = 0.04). Poor long-term outcome (EDSS ≥4) was more common in patients with older onset age (41.9 ± 15 vs. 36.8 ± 15.6, p = 0.02) and motor symptoms at onset (49/76 vs. 66/171, p < 0.0001).

INTERPRETATION

Most TD patients should be considered part of the MS spectrum after excluding MOGAD and NMOSD. Motor symptoms and older age at presentation portend a poor outcome.

Spinal cord and brain corticospinal tract lesions are associated with motor progression in tumefactive multiple sclerosis

BACKGROUND

Spinal cord lesions have been associated with progressive disease in individuals with typical relapsing remitting MS (RRMS).

OBJECTIVE

In the current study, we aimed to determine if progressive disease is associated with spinal cord lesions in those with tumefactive multiple sclerosis (MS).

METHODS

Retrospective chart review of individuals presenting to Mayo Clinic with tumefactive MS with spinal cord MRIs available (n=159). Clinical data were extracted by chart review. Brain and spinal cord MRIs were reviewed to characterize the tumefactive demyelinating lesion(s) and assess the burden of spinal cord disease.

RESULTS

A total of 69 (43%) had spinal cord lesions. Progressive demyelinating disease was documented in 13 (8%); the majority (11/13) with secondary progressive disease. The method of progression was myelopathic in 8/13 (62%), cognitive in 3/13 (23%), motor from a supratentorial lesion in 2/13 (16%). EDSS at last follow-up was higher in those with progression than those without (median 6.0 (2.0-10.0) vs. 2.5 (0-10.0), p = < 0.001). Progressive demyelinating disease occurred in a minority.

CONCLUSIONS

Patients with progression typically experienced progressive motor impairment, and this occurred exclusively in individuals with lesions in the corticospinal tracts of the brain and/or the spinal cord.

Long-term clinical, imaging and cognitive outcomes association with MS immunopathology

OBJECTIVE

In this observational study on a cohort of biopsy-proven central nervous system demyelinating disease consistent with MS, we examined the relationship between early-active demyelinating lesion immunopattern (IP) with subsequent clinical course, radiographic progression, and cognitive function.

METHODS

Seventy-five patients had at least one early-active lesion on biopsy and were pathologically classified into three immunopatterns based on published criteria. The median time from biopsy at follow-up was 11 years, median age at biopsy - 41, EDSS - 4.0. At last follow-up, the median age was 50, EDSS - 3.0. Clinical examination, cognitive assessment (CogState battery), and 3-Tesla-MRI (MPRAGE/FLAIR/T2/DIR/PSIR/DTI) were obtained.

RESULTS

IP-I was identified in 14/75 (19%), IP-II was identified in 41/75 (56%), and IP-III was identified in 18/75 (25%) patients. Patients did not differ significantly by immunopattern in clinical measures at onset or last follow-up. The proportions of disease courses after a median of 11 years were similar across immunopatterns, relapsing-remitting being most common (63%), followed by monophasic (32%). No differences in volumetric or DTI measures were found. CogState performance was similar for most tasks. A slight yet statistically significant difference was identified for episodic memory scores, with IP-III patients recalling one word less on average.

INTERPRETATION

In this study, immunopathological heterogeneity of early-active MS lesions identified at biopsy does not correlate with different long-term clinical, neuroimaging or cognitive outcomes. This could be explained by the fact that while active white matter lesions are pathological substrates for relapses, MS progression is driven by mechanisms converging across immunopatterns, regardless of pathogenic mechanisms driving the acute demyelinated plaque.

Remyelination in Multiple Sclerosis: Findings in the Cuprizone Model

Remyelination therapies, which are currently under development, have a great potential to delay, prevent or even reverse disability in multiple sclerosis patients. Several models are available to study the effectiveness of novel compounds in vivo, among which is the cuprizone model. This model is characterized by toxin-induced demyelination, followed by endogenous remyelination after cessation of the intoxication. Due to its high reproducibility and ease of use, this model enjoys high popularity among various research and industrial groups. In this review article, we will summarize recent findings using this model and discuss the potential of some of the identified compounds to promote remyelination in multiple sclerosis patients.

Pathogenic autoantibodies in multiple sclerosis - from a simple idea to a complex concept

The role of autoantibodies in multiple sclerosis (MS) has been enigmatic since the first description, many decades ago, of intrathecal immunoglobulin production in people with this condition. Some studies have indicated that MS pathology is heterogeneous, with an antibody-associated subtype - characterized by B cells (in varying quantities), antibodies and complement - existing alongside other subtypes with different pathologies. However, subsequent evidence suggested that some cases originally diagnosed as MS with autoantibody-mediated demyelination were more likely to be neuromyelitis optica spectrum disorder or myelin oligodendrocyte glycoprotein antibody-associated disease. These findings raise the important question of whether an autoantibody-mediated MS subtype exists and whether pathogenic MS-associated autoantibodies remain to be identified. Potential roles of autoantibodies in MS could range from specific antibodies defining the disease to a non-disease-specific amplification of cellular immune responses and other pathophysiological processes. In this Perspective, we review studies that have attempted to identify MS-associated autoantibodies and provide our opinions on their possible roles in the pathophysiology of MS.

Motor Behavioral Deficits in the Cuprizone Model: Validity of the Rotarod Test Paradigm

Multiple Sclerosis (MS) is a neuroinflammatory disorder, which is histopathologically characterized by multifocal inflammatory demyelinating lesions affecting both the central nervous system’s white and grey matter. Especially during the progressive phases of the disease, immunomodulatory treatment strategies lose their effectiveness. To develop novel progressive MS treatment options, pre-clinical animal models are indispensable. Among the various different models, the cuprizone de- and remyelination model is frequently used. While most studies determine tissue damage and repair at the histological and ultrastructural level, functional readouts are less commonly applied. Among the various overt functional deficits, gait and coordination abnormalities are commonly observed in MS patients. Motor behavior is mediated by a complex neural network that originates in the cortex and terminates in the skeletal muscles. Several methods exist to determine gait abnormalities in small rodents, including the rotarod testing paradigm. In this review article, we provide an overview of the validity and characteristics of the rotarod test in cuprizone-intoxicated mice.

The Potential for EBV Vaccines to Prevent Multiple Sclerosis

There is increasing evidence suggesting that Epstein-Barr virus infection is a causative factor of multiple sclerosis (MS). Epstein-Barr virus (EBV) is a human herpesvirus, Human Gammaherpesvirus 4. EBV infection shows two peaks: firstly, during early childhood and, secondly during the teenage years. Approximately, 90-95% of adults have been infected with EBV and for many this will have been a subclinical event. EBV infection can be associated with significant morbidity and mortality; for example, primary infection in older children or adults is the leading cause of infectious mononucleosis (IM). A disrupted immune response either iatrogenically induced or through genetic defects can result in lymphoproliferative disease. Finally, EBV is oncogenic and is associated with several malignancies. For these reasons, vaccination to prevent the damaging aspects of EBV infection is an attractive intervention. No EBV vaccines have been licensed and the prophylactic vaccine furthest along in clinical trials contains the major virus glycoprotein gp350. In a phase 2 study, the vaccine reduced the rate of IM by 78% but did not prevent EBV infection. An EBV vaccine to prevent IM in adolescence or young adulthood is the most likely population-based vaccine strategy to be tested and adopted. National registry studies will need to be done to track the incidence of MS in EBV-vaccinated and unvaccinated people to see an effect of the vaccine on MS. Assessment of vaccine efficacy with MS being a delayed consequence of EBV infection with the average age of onset being approximately 30 years of age represents multiple challenges.

Ponesimod in the Treatment of Relapsing Forms of Multiple Sclerosis: An Update on the Emerging Clinical Data

Sphingosine 1-phosphate (S1P) receptors are bioactive lipid metabolites that bind five different types of receptors expressed ubiquitously in human body and mediate a broad range of biological functions. Targeting S1P receptors is nowadays a well-established pharmacological strategy to treat multiple sclerosis (MS). However, the adverse events associated with the ancestor (fingolimod), especially in terms of heart conduction and slow reversibility of its pharmacodynamics effect on lymphocytes, have stimulated a search for a S1P modulator with greater selectivity for S1P1 (the most important immune mechanism to prevent MS-related neuroinflammation). Ponesimod is a second-generation, orally active, directly bioavailable, highly selective, and rapidly reversible modulator of the S1P1 receptor. Gradual 14-day up-titration of ponesimod mitigates its first-dose effects on heart rate and facilitates its use over fingolimod, as it does not require first-dose cardiac monitoring. Ponesimod is rapidly eliminated within 1 week of discontinuation, thereby representing a more manageable approach in case of vaccination, pregnancy, or adverse events. However, the fast reversibility of ponesimod may also raise concerns about the possibility of a rapid reactivation of disease activity following its discontinuation. Ponesimod was recently approved for the treatment of relapsing MS forms on the basis of a Phase III, double-blind, double-dummy, randomized clinical trial (OPTIMUM) that demonstrated the superiority of ponesimod over teriflunomide on disease activity markers, without unexpected safety concerns. This review summarizes the pharmacodynamic and pharmacokinetic characteristics of ponesimod, and the main Phase II and III studies that led to its approval. Comparisons of ponesimod with other S1P receptor modulators currently available for MS (fingolimod, ozanimod, siponimod) are also provided.

Population-based incidence and clinico-radiological characteristics of tumefactive demyelination in Olmsted County, Minnesota, United States

BACKGROUND AND PURPOSE

Tumefactive demyelination (TD) presents with large inflammatory lesions mimicking tumors or other space-occupying lesions. Limited epidemiological, clinical and radiological data exist for TD. We aimed to report the incidence rate, and clinical and radiological features of TD in Olmsted County, Minnesota.

METHODS

We retrospectively reviewed patients with central nervous system inflammatory demyelination-related diagnostic codes (January 1, 1998 to December 31, 2018) in the Rochester Epidemiology Project database, and adjusted incidence rates by age and sex to the 2010 US total population. We used the Expanded Disability Status Scale (EDSS) to assess outcomes (index attack and last follow-up).

RESULTS

Of 792 multiple sclerosis (MS) patients, 15 (eight males, seven females) had tumefactive MS, representing 1.9% of the MS population. The median (range) age at attack onset was 34.2 (2-61) years. Tumefactive lesion was the first clinical MS attack in 8/16 patients. Cerebrospinal fluid oligoclonal bands (OCBs) were present in 8/12 patients and 11/16 patients met the Barkhof criteria for dissemination in space. Most patients remained fully ambulatory (EDSS score ≤4 in 13/16 patients [81%]) after a median (range) follow-up duration of 10.5 (1-20.5) years. Age-adjusted annual incidence rates were 0.46/100,000 (95% confidence interval [CI] 0.12-0.81) for female patients, 0.66/100,000 (95% CI 0.23-1.02) for male patients, and 0.56/100,000 [95% CI 0.28-0.83] overall. When age- and sex-adjusted to the 2010 US total population, the overall annual incidence rate was 0.57 (95% CI 0.28-0.84). Despite aggressive clinical presentation at disease onset, most patients remained fully ambulatory (EDSS score ≤4 in 13/16 patients) with a relapsing-remitting course.

CONCLUSIONS

Although incidence is rare, TD should be suspected in patients presenting with subacutely progressive neurological deficits associated with magnetic resonance imaging findings of ring enhancement, apparent diffusion coefficient restriction, and OCB on spinal fluid analysis.

OUP accepted manuscript

Although major progress in multiple sclerosis research has been made during the last decades, key questions related to the cause and the mechanisms of brain and spinal cord pathology remain unresolved. These cover a broad range of topics, including disease aetiology, antigenic triggers of the immune response inside and/or outside the CNS and mechanisms of inflammation, demyelination neurodegeneration and tissue repair. Most of these questions can be addressed with novel molecular technologies in the injured CNS. Access to brain and spinal cord tissue from multiple sclerosis patients is, therefore, of critical importance. High-quality tissue is provided in part by the existing brain banks. However, material from early and highly active disease stages is limited. An initiative, realized under the patronage of the European Charcot Foundation, gathered together experts from different disciplines to analyse the current state of multiple sclerosis tissues collected post-mortem or as biopsies. Here, we present an account of what material is currently available and where it can be accessed. We also provide recommendations on how tissue donation from patients in early disease stages could be potentially increased and for procedures of tissue sampling and preservation. We also suggest to create a registry of the available tissues that, depending on the source (autopsy versus biopsy), could be made accessible to clinicians and researchers.