Patients with multiple sclerosis acquire disability either through relapse-associated worsening (RAW) or progression independent of relapse activity (PIRA). This study addresses the relative contribution of relapses to disability worsening over the course of the disease, how early progression begins and the extent to which multiple sclerosis therapies delay disability accumulation. Using the Novartis-Oxford multiple sclerosis (NO.MS) data pool spanning all multiple sclerosis phenotypes and paediatric multiple sclerosis, we evaluated ∼200 000 Expanded Disability Status Scale (EDSS) transitions from >27 000 patients with ≤15 years follow-up. We analysed three datasets: (i) A full analysis dataset containing all observational and randomized controlled clinical trials in which disability and relapses were assessed (n = 27 328); (ii) all phase 3 clinical trials (n = 8346); and (iii) all placebo-controlled phase 3 clinical trials (n = 4970). We determined the relative importance of RAW and PIRA, investigated the role of relapses on all-cause disability worsening using Andersen-Gill models and observed the impact of the mechanism of worsening and disease-modifying therapies on the time to reach milestone disability levels using time continuous Markov models. PIRA started early in the disease process, occurred in all phenotypes and became the principal driver of disability accumulation in the progressive phase of the disease. Relapses significantly increased the hazard of all-cause disability worsening events; following a year in which relapses occurred (versus a year without relapses), the hazard increased by 31–48% (all P < 0.001). Pre-existing disability and older age were the principal risk factors for incomplete relapse recovery. For placebo-treated patients with minimal disability (EDSS 1), it took 8.95 years until increased limitation in walking ability (EDSS 4) and 18.48 years to require walking assistance (EDSS 6). Treating patients with disease-modifying therapies delayed these times significantly by 3.51 years (95% confidence limit: 3.19, 3.96) and 3.09 years (2.60, 3.72), respectively. In patients with relapsing-remitting multiple sclerosis, those who worsened exclusively due to RAW events took a similar length of time to reach milestone EDSS values compared with those with PIRA events; the fastest transitions were observed in patients with PIRA and superimposed relapses. Our data confirm that relapses contribute to the accumulation of disability, primarily early in multiple sclerosis. PIRA begins in relapsing-remitting multiple sclerosis and becomes the dominant driver of disability accumulation as the disease evolves. Pre-existing disability and older age are the principal risk factors for further disability accumulation. The use of disease-modifying therapies delays disability accrual by years, with the potential to gain time being highest in the earliest stages of multiple sclerosis.

There is an increasing recognition that inflammation plays a critical role in neurodegenerative diseases of the CNS, including Alzheimer’s disease, amyotrophic lateral sclerosis, Parkinson’s disease, and the prototypic neuroinflammatory disease multiple sclerosis (MS). Differential immune responses involving the adaptive versus the innate immune system are observed at various stages of neurodegenerative diseases, and may not only drive disease processes but could serve as therapeutic targets. Ongoing investigations into the specific inflammatory mechanisms that play roles in disease causation and progression have revealed lessons about inflammation-driven neurodegeneration that can be applied to other neurodegenerative diseases. An increasing number of immunotherapeutic strategies that have been successful in MS are now being applied to other neurodegenerative diseases. Some approaches suppress CNS immune mechanisms, while others harness the immune system to clear deleterious products and cells. This Review focuses on the mechanisms by which inflammation, mediated either by the peripheral immune response or by endogenous CNS immune mechanisms, can affect CNS neurodegeneration.

Research from JAMA Neurology — Increased Relapse Rate in Pediatric-Onset Compared With Adult-Onset Multiple Sclerosis

Neuronal injury is a universal event that occurs in disease processes that affect both the central and peripheral nervous systems. A blood biomarker linked to neuronal injury would provide a critical measure to understand and treat neurologic diseases. Neurofilament light chain (NfL), a cytoskeletal protein expressed only in neurons, has emerged as such a biomarker. With the ability to quantify neuronal damage in blood, NfL is being applied to a wide range of neurologic conditions to investigate and monitor disease including assessment of treatment efficacy. Blood NfL is not specific for one disease and its release can also be induced by physiological processes. Longitudinal studies in multiple sclerosis, traumatic brain injury, and stroke show accumulation of NfL over days followed by elevated levels over months. Therefore, it may be hard to determine with a single measurement when the peak of NfL is reached and when the levels are normalized. Nonetheless, measurement of blood NfL provides a new blood biomarker for neurologic diseases overcoming the invasiveness of CSF sampling that restricted NfL clinical application. In this review, we examine the use of blood NfL as a biologic test for neurologic disease.

Objective: This study was undertaken to investigate the gut microbiome in progressive multiple sclerosis (MS) and how it relates to clinical disease.Methods: We sequenced the microbiota from healthy controls and relapsing–remitting MS (RRMS) and progressive MS patients and correlated the levels of bacteria with clinical features of disease, including Expanded Disability Status Scale (EDSS), quality of life, and brain magnetic resonance imaging lesions/atrophy. We colonized mice with MS‐derivedAkkermansiaand induced experimental autoimmune encephalomyelitis (EAE).Results: Microbiota β‐diversity differed between MS patients and controls but did not differ between RRMS and progressive MS or differ based on disease‐modifying therapies. Disease status had the greatest effect on the microbiome β‐diversity, followed by body mass index, race, and sex. In both progressive MS and RRMS, we found increasedClostridium bolteae,Ruthenibacterium lactatiformans, andAkkermansiaand decreasedBlautia wexlerae,Dorea formicigenerans, andErysipelotrichaceae CCMM. Unique to progressive MS, we found elevatedEnterobacteriaceaeandClostridium g24 FCEYand decreasedBlautiaandAgathobaculum. SeveralClostridiumspecies were associated with higher EDSS and fatigue scores. Contrary to the view that elevatedAkkermansiain MS has a detrimental role, we found thatAkkermansiawas linked to lower disability, suggesting a beneficial role. Consistent with this, we found thatAkkermansiaisolated from MS patients ameliorated EAE, which was linked to a reduction in RORγt+ and IL‐17–producing γδ T cells.Interpretation: Whereas some microbiota alterations are shared in relapsing and progressive MS, we identified unique bacteria associated with progressive MS and clinical measures of disease. Furthermore, elevatedAkkermansiain MS may be a compensatory beneficial response in the MS microbiome. ANN NEUROL 2021;89:1195–1211

Background The prevalence of pediatric-onset multiple sclerosis (MS) in the United States is unknown. Objective In a large cohort of MS patients, we sought to identify the proportion with first symptom-onset below the age of 18 years, and to compare their demographic and disease characteristics to a typical adult-onset MS population. Methods Patients seen at the Partners Multiple Sclerosis Center, Brigham and Women’s Hospital, Boston, Massachusetts, with clinical histories and characteristics of first symptoms recorded in an electronic database, were included in this study. Results We found that 3.06% of patients with a recorded MS history experienced a first attack under the age of 18 years of age compared to 30.83% of patients who experienced first symptoms between the ages of 25–35 years. Gender proportions were similar in both groups, with the exception of a lower female preponderance in pre-pubertal-onset patients. There was a higher proportion of non-Caucasians in the younger cohort. Localization of first symptoms was similar in the two groups. Conclusion About 3% of MS patients experience their first symptom prior to the age of 18 years. Standardized follow-up is required after a first demyelinating attack in childhood, which may lead to earlier diagnosis and treatment of pediatric-onset MS.