Interest in neurofilaments has risen sharply in recent years with recognition of their potential as biomarkers of brain injury or neurodegeneration in CSF and blood. This is in the context of a growing appreciation for the complexity of the neurobiology of neurofilaments, new recognition of specialized roles for neurofilaments in synapses and a developing understanding of mechanisms responsible for their turnover. Here we will review the neurobiology of neurofilament proteins, describing current understanding of their structure and function, including recently discovered evidence for their roles in synapses. We will explore emerging understanding of the mechanisms of neurofilament degradation and clearance and review new methods for future elucidation of the kinetics of their turnover in humans. Primary roles of neurofilaments in the pathogenesis of human diseases will be described. With this background, we then will review critically evidence supporting use of neurofilament concentration measures as biomarkers of neuronal injury or degeneration. Finally, we will reflect on major challenges for studies of the neurobiology of intermediate filaments with specific attention to identifying what needs to be learned for more precise use and confident interpretation of neurofilament measures as biomarkers of neurodegeneration.

Treatments with a range of efficacy and risk of adverse events have become available for the management of multiple sclerosis (MS). However, now the heterogeneity of clinical expression and responses to treatment pose major challenges to improving patient care. Selecting and managing the drug best balancing benefit and risk demands a new focus on the individual patient. Personalised medicine for MS is based on improving the precision of diagnosis for each patient in order to capture prognosis and provide an evidence-based framework for predicting treatment response and personalising patient monitoring. It involves development of predictive models involving the integration of clinical and biological data with an understanding of the impact of disease on the lives of individual patients. Here, we provide a brief, selective review of challenges to personalisation of the management of MS and suggest an agenda for stakeholder engagement and research to address them.

Background: REFINE was an exploratory, dose- and frequency-blinded, prospective, randomized, dose-ranging study in relapsing–remitting multiple sclerosis (RRMS) patients. Objective: To examine the efficacy, safety, and tolerability of natalizumab administered via various regimens in RRMS patients. Methods: Clinically stable RRMS patients previously treated with 300 mg natalizumab intravenously for ⩾12 months were randomized to one of six natalizumab regimens over 60 weeks: 300 mg administered intravenously or subcutaneously every 4 weeks (Q4W), 300 mg intravenously or subcutaneously every 12 weeks (Q12W), or 150 mg intravenously or subcutaneously Q12W. The primary endpoint was the mean cumulative number of combined unique active magnetic resonance imaging (MRI) lesions at week 60. Results: In total, 290 patients were enrolled. All Q12W dosing arms were associated with increased clinical and MRI disease activity and closed early; ⩾39.5% of patients in each Q12W arm met rescue criteria. In the 300 mg intravenous and subcutaneous Q4 W arms, the mean cumulative number of combined unique active MRI lesions was 0.23 and 0.02, respectively; annualized relapse rates were 0.07 and 0.08, respectively; and trough natalizumab serum levels and α4-integrin saturation were comparable. Conclusion: Natalizumab 300 mg subcutaneous Q4W was comparable to 300 mg intravenous Q4W dosing with respect to efficacy, pharmacokinetics/pharmacodynamics, and safety.

IMPORTANCE Data are needed on the potential long-term prognostic association of serum neurofilament light in multiple sclerosis (MS). OBJECTIVE To evaluate serum neurofilament light as a biomarker associated with long-term disease outcomes in clinically isolated syndrome. DESIGN, SETTING, AND PARTICIPANTS This post hoc cohort study used data from the Controlled High-Risk Avonex Multiple Sclerosis Prevention Study, a 36-month, multicenter, placebocontrolled interferon β-1a randomized clinical trial conducted from April 1996 to March 2000, and its long-term (5-and 10-year) extension study from February 2001 to March 2009. Participants included individuals with a symptomatic initial demyelinating event and brain magnetic resonance imaging (MRI) lesions suggestive of MS. Data were analyzed from April 2017 through 2019. EXPOSURE The variable of interest was naturally occurring serum neurofilament light concentration MAIN OUTCOMES AND MEASURES Gadolinium-enhancing (Gd +) lesion number, T2 lesion volume, and brain parenchymal fraction, a measure of brain atrophy were measured at baseline and 5 and 10 years. Multivariate regression models evaluated whether age, sex, and baseline covariates, including serum neurofilament light, brain parenchymal fraction, Expanded Disability Status Scale, Gd + lesion count, and T2 lesion volume, were associated with brain parenchymal fraction changes over 5 and 10 years. RESULTS Among 308 included participants (mean [SD] age, 33.2 [7.6] years; 234 [76.0%] women), baseline serum neurofilament light concentrations were associated with Gd + lesions (Spearman r = 0.41; P < .001) and T2 lesion volume (Spearman r = 0.42; P < .001). Among covariates for brain parenchymal fraction change, serum neurofilament light concentration had the greatest correlation with change in brain parenchymal fraction at 5 years

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Altered lipid metabolism is a feature of chronic inflammatory disorders. Increased plasma lipids and lipoproteins have been associated with multiple sclerosis (MS) disease activity. Our objective was to characterise the specific lipids and associated plasma lipoproteins increased in MS and to test for an association with disability. Plasma samples were collected from 27 RRMS patients (median EDSS, 1.5, range 1–7) and 31 healthy controls. Concentrations of lipids within lipoprotein sub-classes were determined from NMR spectra. Plasma cytokines were measured using the MesoScale Discovery V-PLEX kit. Associations were tested using multivariate linear regression. Differences between the patient and volunteer groups were found for lipids within VLDL and HDL lipoprotein sub-fractions (p < 0.05). Multivariate regression demonstrated a high correlation between lipids within VLDL sub-classes and the Expanded Disability Status Scale (EDSS) (p < 0.05). An optimal model for EDSS included free cholesterol carried by VLDL-2, gender and age (R2 = 0.38, p < 0.05). Free cholesterol carried by VLDL-2 was highly correlated with plasma cytokines CCL-17 and IL-7 (R2 = 0.78, p < 0.0001). These results highlight relationships between disability, inflammatory responses and systemic lipid metabolism in RRMS. Altered lipid metabolism with systemic inflammation may contribute to immune activation.

Open Access. This is an open access article distributed under the terms of the CC-BY-NC-ND License.

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