Background

Following demyelination, remyelination may take place in multiple sclerosis (MS) lesions, but this process is heterogeneous and often fails. Brain perfusion was shown to impact remyelination in rodents, but this relationship has never been assessed in patients with MS. Positron emission tomography (PET) with 11C-PiB allows to simultaneously map demyelination and remyelination in vivo, and to generate quantitative maps of brain perfusion.

Objectives

To analyse the relationship between baseline perfusion and subsequent myelin content changes in white matter (WM) lesions.

Methods

11C-PIB PET and 3T MRI were acquired in 15 patients with relapsing-remitting MS at baseline and after 2-4 months. Nine hundred and four lesions were identified at baseline on T2-weighted scans with the exclusion of gadolinium-enhancing lesions to avoid artefacts in perfusion quantification. Logan reference graphical analysis and simplified reference tissue model were used to generate voxelwise maps of distribution volume ratio (DVR) and relative delivery (R1) from 11C-PiB images, respectively. Perfusion at baseline, as measured by R1, and the percentage of demyelinating and remyelinating voxels over the follow-up, derived from DVR maps, were calculated for each lesion.

Mixed-effect models were employed to evaluate the association between perfusion at baseline and the percentage of demyelinating and remyelinating voxels over the follow-up in WM lesions. A logistic regression was employed to determine the impact of perfusion on the probability of lesions to successfully repair, I.e. to remyelinate at least 50% of their demyelinated voxels at baseline and to undergo demyelination over the follow-up in less than 25% of voxels classified as normally myelinated at study entry.

Results

WM lesions showed lower perfusion compared to normal-appearing WM (0.43±0.08 vs 0.49±0.03, p<0.001), although single-lesion R1 values were remarkably heterogeneous (range: [0.08-2.5]). At the single lesion level, a higher perfusion at baseline was associated with a more extensive remyelination (β=0.32, p<0.001) and a reduced demyelination (β=-0.28, p<0.001) over the follow-up. Lesion-specific perfusion at baseline was an independent predictor of successful myelin repair over the follow-up (OR=8.4, p<0.001).

Conclusions

The level of perfusion of single MS lesions is critical for myelin repair and may be one key factor underlying the heterogeneous levels of remyelination across patients with MS.

Background

Risk factors associated with the severity of COVID-19 in patients with multiple sclerosis (MS) begin to be identified from several cohort studies. Disease modifying therapies (DMTs) may modify the risk of developing a severe COVID-19 infection, beside identified risk factors such as age and comorbidities.

Objectives

The objective was to describe the clinical characteristics and outcomes in patients with COVID-19 and to identify the factors associated with COVID-19 severity.

Methods

This multicenter, retrospective, observational cohort study (COVISEP registry, NCT04355611) included patients with MS presenting with a confirmed or highly suspected diagnosis of COVID-19 between March 1, 2020 and July 14, 2020. The main outcome was COVID-19 severity assessed on a 7-point ordinal scale (ranging from 1: not hospitalized, no limitations on activities, to 7: death; cutoff at 3: hospitalized, not requiring supplemental oxygen). We collected demographics, neurological history, Expanded Disability Severity Score (EDSS), comorbidities, COVID-19 characteristics and outcome. Univariate and multivariate logistic regression models were used to estimate the influence of collected variables on COVID-19 outcome.

Results

A total of 405 patients (mean age: 44.7 years, female/male: 293/112, mean disease duration: 13.4 years) were analyzed. Seventy-eight patients (19.3%) had a COVID-19 severity score ≥ 3, and 12 patients (3.0%) died from COVID-19. Median EDSS was 2.0 (range: 0-9.5), 326 patients (80.5%) were on DMT. There was a higher proportion of patients with COVID-19 severity score ≥ 3 among patients with no DMT relative to patients on DMTs (39.2% versus 14.4%, p<0.001). Multivariate logistic regression models determined that age (OR for 10 years: 1.8, 95% CI: 1.4-2.4), EDSS (OR for EDSS ≥ 6: 4.5, 95% CI: 2.0-10.0) were independent risk factors for COVID-19 severity score ≥ 3 (hospitalization or higher severity) while immunomodulatory treatment (interferon or glatiramer acetate) was associated with lower risk of COVID-19 severity score ≥ 3 (OR: 0.2, 95% CI: 0.05-0.8). EDSS was associated with the highest variability of COVID-19 severe outcome (R²= 0.18), followed by age (R²= 0.06) and immunomodulatory treatment (R²= 0.02).

Conclusions

EDSS and age were independent risk factors of severe COVID-19, while exposure to immunomodulatory DMTs (interferon and glatiramer acetate) were independently associated with lower COVID-19 severity. We did not find an association between other DMTs exposure (including immunosuppressive therapies) and COVID-19 severity. The identification of these risk factors should provide the rationale for an individual strategy regarding clinical management of MS patients during the COVID-19 pandemic.

Background

Restrictions imposed by the National and local authorities to mitigate the spread of Coronavirus disease-19 (COVID-19) posed unique challenges in the access to care and management of people with multiple sclerosis (PwMS).

Objectives

To collect data about the impact of the COVID-19 emergency on access to care for PwMS and analyze influence on treatment practices of MS neurologists worldwide.

Methods

Between March and July 2020 the European Committee for Treatment and Research in MS (ECTRIMS) promoted an online survey among Council members and MS specialists worldwide, covering five major areas: general information; MS patient access to care; management of relapses and visits; use of disease modifying therapy (DMT); experience with COVID-19 MS patients.

Results

Three-hundred-sixty neurologists (46% females, median age 48 years) from 52 countries (Europe 68%; Central/South America 17%; North America 10%, others 5%) completed the survey. Seventy-five percent worked within a specialized MS centre, 42% followed > 1000 patients. Ninety-eight percent of respondents reported COVID-19 pandemic had a negative impact on patients’ care. Routine MS clinical activities were suspended in 63% of cases and only urgent visits were guaranteed. Telemedicine services (mainly calls, video-calls, messaging) were provided by 90% of respondents: only in 20% of cases telemedicine was already in use in the practice. Forty-five percent revealed changes in relapse treatment: dosage and/or duration reduction 30%; treatment offered only for severe relapses 36%; treatment delivered at home 28%. As for DMT, 98% of respondents felt no modification was needed for interferons and glatiramer; 48-60% deemed no change was needed for dimethyl fumarate, teriflunomide, fingolimod and siponimod, while nearly 25% considered switching/suspending these agents based on lymphopenia. On the other hand, for natalizumab 31% applied an extended-dose regimen, for cladribine and alemtuzumab 42-52% considered postponing treatment in any case as the best choice. For anti-CD20 monoclonal antibodies, postponing treatment in any case (32%) or based on the patient immunophenotype (25%) were the preferred options. Sixty-one percent of respondents had at least one patient affected by COVID-19, 27% had at least one patient with severe infection; 70% of severe cases were on DMT. Finally, 11% of respondents reported at least one COVID-19 related death and 36% of fatal cases were on DMT.

Conclusions

While analysis of geographic differences is ongoing, the survey highlighted that COVID-19 pandemic is having a major impact on MS care worldwide. Telemedicine has a great potential to mitigate issues and needs to be potentiated/implemented de novo at most centres. As for DMT, major changes regarded cladribine, alemtuzumab and anti-CD20. Collecting standardized, reliable data on the potential impact of DMT on COVID-19 in PwMS is urgently needed to inform appropriate treatment decisions.

Background

Microstructural alterations in the Normal-Appearing White Matter (NAWM) preceeding the onset of a new lesion have been described using advanced MRI in patients with MS. However, the biological substrate of these alterations remains poorly understood due to the lack of specificity of the MRI signal. We have previously shown that Positron Emission Tomography (PET) with 11C-PIB has the potential to quantify myelin content changes in WM lesions. Interestingly, dynamic 11C-PIB PET acquisitions, including early frames, enable the estimation of regional brain perfusion too.

Objectives

To characterize whether perfusion changes, microstructural damage and demyelination could precede lesion appearance on T2-weighted (T2-w) MRI images.

Methods

Longitudinal dynamic 11C-PIB PET and 3T MRI, including diffusion weighted and magnetization transfer imaging, were acquired in 19 active patients with relapsing-remitting MS. Following baseline scans, patients underwent a second evaluation after 1-2 month (n= 10) or after 3-4 months (n=9). Prelesional areas were defined as the baseline NAWM areas which became hyperintensities on the second T2-w image. Logan reference graphical analysis and simplified reference tissue model were respectiveley used to generate voxelwise maps of Distribution Volume Ratio (DVR), and relative delivery (R1) from 11C-PIB images. Myelin content, reflected by DVR, and perfusion, measured by R1, were extracted for each prelesional area and the corresonding contralateral area in the NAWM. Magnetization transfer ratio (MTR), fractional anisotropy (FA), radial and axial diffusivity (RD and AD) were calculated in the same areas. Paired t-test were used to test differences in DVR, R1, MTR, FA, RD and AD between the prelesional and its contralateral areas.

Results

We identified 77 prelesional areas. In the subgroup of patients with a 1-2 months follow-up, prelesional areas (45 out of 77) showed a higher perfusion (8.5%, p=0.03), increased RD (4.2%, p=0.003), lower MTR (-1.2%, p=0.008) and reduced FA (-6.2%, p=0.008), compared to contralateral NAWM areas, while no difference was detected in DVR (p=0.4). No statistical differences were found in the subgroup of patients with a follow-up of 3-4 months.

Conclusions

One-two months before becoming hyperintense on T2-w MRI, prelesional areas are characterized by an increased perfusion associated with microstructural changes, but not by demyelination.

Background

In multiple sclerosis (MS), pathological changes are not limited to lesions, but extensively involve normal-appearing tissues, being more pronounced in perilesions. Histological studies have shown that the pathological changes affecting perilesions mainly result from the ongoing damage in demyelinating lesions. Similarly, the structural integrity of perilesions could depend on the extent of myelin repair at the lesional level, which can be explored in vivo by positron emission tomography (PET) with 11C-PiB.

Objectives

To assess in a longitudinal study whether myelin content changes in white matter lesions, measured with 11C-PiB PET, influence the microstructural integrity of the surrounding perilesions over time, explored by diffusion tensor imaging and magnetization transfer (MT)-derived metrics.

Methods

Nineteen patients with MS underwent a longitudinal PET/MRI study. Voxel-wise maps of 11C-PiB distribution volume ratio, reflecting myelin content, were used to calculate for each patient in each non-enhancing lesion 3 indices of myelin content change: the percentage of demyelinated voxels at baseline, and the percentage of demyelinating and remyelinating voxels over the follow-up. From each 3 mm-thick perilesional area surrounding lesions, the change over time (delta) of fractional anisotropy (FA), mean diffusivity (MD) and MT ratio (MTR), reflecting microstructural damage, was calculated. Associations between the indices of myelin content change and the delta FA, MD, and MTR in perilesions were assessed using multivariate linear regressions. Perilesions were classified in “improving” or “worsening” according to the sign of the change of the microstructural parameters and a multivariate logistic regression was used to test which PET-derived index was independently associated with perilesion class.

Results

A higher percentage of demyelinated voxels at baseline and of demyelinating voxels over the follow-up inside lesions were associated with a more severe microstructural damage developing over time in perilesions (p<0.001). Conversely, a higher percentage of remyelinating lesional voxels correlated with a more preserved perilesional microstructure at the follow-up (p<0.001). The percentage of remyelinating voxels inside lesions was the only independent predictor of perilesion improvement (p=0.001). We found that at least 43% of the demyelinated volume had to remyelinate to predict a favorable evolution of the microstructure of perilesional tissue (AUC=0.8).

Conclusions

Lesional remyelination effectively protects the integrity of surrounding tissues over time, possibly by reducing the extent of Wallerian degeneration and rescuing damaged axons.

Background

Siponimod, a potent and highly selective sphingosine 1-phosphate receptor modulator, has recently been approved for treatment of relapsing forms of MS and active SPMS.

Objectives

To assess remyelination and neuroprotective potential of siponimod in a Xenopus remyelination and a mouse optic neuritis (EAEON) model using histological analysis and longitudinal visual system readouts.

Methods

We used a conditional demyelination transgenic Xenopus laevis model (MBP-GFP-NTR), in which oligodendrocyte apoptosis can be induced by metronidazole (MTZ) treatment. After MTZ withdrawal, remyelination was assessed with or without siponimod (0.1nM-1µM). In a pharmacokinetics study, brain siponimod levels were analysed. EAEON was induced in female C57BL/6J mice immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG_35-55) and continuously fed with vehicle- or siponimod-loaded pellets at 10 or 30 mg/kg of food, either prophylactically or therapeutically, over 90 days. Sections of the optic nerve (Xenopus and mouse) were used to detect de- and remyelination, as well as inflammatory infiltrates. In mice, thickness of retinal layers and visual function were assessed by optical coherence tomography and optokinetic response, respectively. Circulating lymphocytes (flow-cytometry) and siponimod blood and brain levels were analysed at the end of the experiment.

Results

Treatment of demyelinated tadpoles with siponimod (1nM in swimming water) improved remyelination by a factor of 2.3±0.2 fold in comparison to control. The dose-response of siponimod efficiency to accelerate remyelination showed a bell-shaped curve with a maximum remyelination effect at concentrations ranging between 70-80 nM in tissues. In the EAEON mouse model, prophylactic siponimod treatments with 10 or 30 mg/kg attenuated the EAEON clinical scores by about 80% and 95%, respectively, and reduced the retinal neurodegeneration and the loss of visual function. Interestingly, therapeutic treatment starting at day 14 of EAEON had no impact on optic nerve immune cell infiltrates but resulted in increased myelin levels and protection of inner retinal layers also in a bell-shaped dose-response curve with significant protective effects only at the lower dose.

Conclusions

Our data suggest that while siponimod strongly impacts immune cells at higher concentrations (classical dose-response), its effects on remyelination and neuroaxonal survival are dose-dependent following the dynamics of a bell-shaped dose-response curve in both animal models.