A comparative study of CSF neurofilament light and heavy chain protein in MS

Combined Cerebrospinal Fluid Neurofilament Light Chain Protein and Chitinase-3 Like-1 Levels in Defining Disease Course and Prognosis in Multiple Sclerosis

Background: Neurofilament light chain protein (NFL) and chitinase3-like1 (CHI3L1) have gained importance recently as prognostic biomarkers in multiple sclerosis (MS). Objectives: We aimed to investigate NFL and CHI3L1 cerebrospinal fluid (CSF) profiles in multiple sclerosis and the informative and prognostic potential of the individual and combined measures. Methods: CSF NFL and CHI3L1 levels were measured in a cross-sectional cohort of 157 MS patients [99 relapsing-remitting (RRMS), 35 secondary progressive (SPMS), and 23 primary progressive (PPMS)]. Clinical relapse and/or gadolinium-enhanced lesions (GEL) in MRI within 90 days from CSF collection by lumbar puncture (LP) were registered and considered as indicators of disease activity. Longitudinal treatment and disability data were evaluated during medical visits with a median follow-up of 50 months. Results: CSF levels of NFL and CHI3L1 were higher in MS patients compared to non-MS controls. In RRMS and SPMS patients, increased NFL levels were associated with clinical relapse, and gadolinium-enhanced lesions in MRI (p < 0.001), while high CHI3L1 levels were characteristic of progressive disease (p = 0.01). In RRMS patients, CSF NFL, and CHI3L1 levels correlated with each other (r = 0.58), and with IgM-oligoclonal bands (p = 0.02 and p = 0.004, respectively). In addition, CSF CHI3L1 concentration was a predictor for 1-point EDSS worsening {HR = 2.99 [95% CI (1.27, 7.07)]} and progression during follow-up {HR = 18 [95% CI (2.31, 141.3)]}. The pattern of combined measure of biomarkers was useful to discriminate MS phenotypes and to anticipate clinical progression: RRMS more frequently presented high NFL combined with low CHI3L1 levels, compared to SPMS (HR 0.41 [0.18-0.82]), and PPMS (HR 0.46 [0.19-0.87]), while elevation of both biomarkers preceded diagnosis of clinical progression in RRMS patients (log rank = 0.02). Conclusions: Individual measures of CSF NFL and CHI3L1 are biomarkers of disease activity and progression, respectively. The pattern of combined measure discriminates MS phenotypes. It also predicts the subset of RRMS patients that will progress clinically allowing early intervention.

Diagnostic Value of Cerebrospinal Fluid Neurofilament Light Protein in Neurology: A Systematic Review and Meta-analysis

IMPORTANCE

Neurofilament light protein (NfL) is elevated in cerebrospinal fluid (CSF) of a number of neurological conditions compared with healthy controls (HC) and is a candidate biomarker for neuroaxonal damage. The influence of age and sex is largely unknown, and levels across neurological disorders have not been compared systematically to date.

OBJECTIVES

To assess the associations of age, sex, and diagnosis with NfL in CSF (cNfL) and to evaluate its potential in discriminating clinically similar conditions.

DATA SOURCES

PubMed was searched for studies published between January 1, 2006, and January 1, 2016, reporting cNfL levels (using the search terms neurofilament light and cerebrospinal fluid) in neurological or psychiatric conditions and/or in HC.

STUDY SELECTION

Studies reporting NfL levels measured in lumbar CSF using a commercially available immunoassay, as well as age and sex.

DATA EXTRACTION AND SYNTHESIS

Individual-level data were requested from study authors. Generalized linear mixed-effects models were used to estimate the fixed effects of age, sex, and diagnosis on log-transformed NfL levels, with cohort of origin modeled as a random intercept.

MAIN OUTCOME AND MEASURE

The cNfL levels adjusted for age and sex across diagnoses.

RESULTS

Data were collected for 10 059 individuals (mean [SD] age, 59.7 [18.8] years; 54.1% female). Thirty-five diagnoses were identified, including inflammatory diseases of the central nervous system (n = 2795), dementias and predementia stages (n = 4284), parkinsonian disorders (n = 984), and HC (n = 1332). The cNfL was elevated compared with HC in a majority of neurological conditions studied. Highest levels were observed in cognitively impaired HIV-positive individuals (iHIV), amyotrophic lateral sclerosis, frontotemporal dementia (FTD), and Huntington disease. In 33.3% of diagnoses, including HC, multiple sclerosis, Alzheimer disease (AD), and Parkinson disease (PD), cNfL was higher in men than women. The cNfL increased with age in HC and a majority of neurological conditions, although the association was strongest in HC. The cNfL overlapped in most clinically similar diagnoses except for FTD and iHIV, which segregated from other dementias, and PD, which segregated from atypical parkinsonian syndromes.

CONCLUSIONS AND RELEVANCE

These data support the use of cNfL as a biomarker of neuroaxonal damage and indicate that age-specific and sex-specific (and in some cases disease-specific) reference values may be needed. The cNfL has potential to assist the differentiation of FTD from AD and PD from atypical parkinsonian syndromes.

Neurofilament light chain as a biomarker in neurological disorders

In the management of neurological diseases, the identification and quantification of axonal damage could allow for the improvement of diagnostic accuracy and prognostic assessment. Neurofilament light chain (NfL) is a neuronal cytoplasmic protein highly expressed in large calibre myelinated axons. Its levels increase in cerebrospinal fluid (CSF) and blood proportionally to the degree of axonal damage in a variety of neurological disorders, including inflammatory, neurodegenerative, traumatic and cerebrovascular diseases. New immunoassays able to detect biomarkers at ultralow levels have allowed for the measurement of NfL in blood, thus making it possible to easily and repeatedly measure NfL for monitoring diseases' courses. Evidence that both CSF and blood NfL may serve as diagnostic, prognostic and monitoring biomarkers in neurological diseases is progressively increasing, and NfL is one of the most promising biomarkers to be used in clinical and research setting in the next future. Here we review the most important results on CSF and blood NfL and we discuss its potential applications and future directions.

Neurofilament light chain in the assessment of patients with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune, inflammatory, and degenerative disease of the central nervous system. Axonal degeneration is triggered by inflammation and is the pathological substrate of progressive disability in patients with MS. Therapeutic interventions can reduce inflammatory activity, thus delaying neurodegeneration and the progression of disability. Disease activity and neurodegeneration are assessed mainly through clinical evaluation and magnetic resonance imaging. These measures lack sensitivity and accuracy, so new biomarkers are necessary. Several markers have been studied and to date the most promising is neurofilament light (NfL), a component of the axonal cytoskeleton, which is released into cerebrospinal fluid (CSF) following axonal damage. In the present study, we review the current knowledge about CSF NfL determination in MS, clinically isolated syndrome, and radiologically isolated syndrome, and critically discuss how CSF NfL measurement may contribute to therapeutic decision-making in these patients.

Blood neurofilament light as a potential endpoint in Phase 2 studies in MS

Objectives

To assess whether neurofilament light chain (NfL) could serve as an informative endpoint in Phase 2 studies in patients with relapsing-remitting multiple sclerosis (RRMS) and estimate the sample size requirements with NfL as the primary endpoint.

Methods

Using data from the Phase 3 FREEDOMS study, we evaluated correlation of NfL at Month 6 with 2-year outcomes: relapses, confirmed disability worsening (CDW), new or enlarging T2 lesions (active lesions), and brain volume loss (BVL). We compared the proportion of treatment effect (PTE) on 2-year relapses and BVL explained by 6-month log-transformed NfL levels with the PTE explained by the number of active lesions over 6 months. We estimated sample size requirements for different treatment effects.

Results

At Month 6, blood NfL levels (pg/mL, median [range]) were lower in the fingolimod arm (fingolimod (n = 132) 18 [8-247]; placebo (n = 114) 26 [8-159], P < 0.001). NfL at 6 months correlated with number of relapses (r = 0.25, P < 0.001), 6-month CDW (hazard ratio 1.83, P = 0.012), active lesions (r = 0.46, P < 0.001), and BVL (r = -0.41, P < 0.001) at Month-24. The PTE (95% CI) on 24-month relapses and BVL explained by 6-month NfL was 25% (8-60%) and 60% (32-132%), and by 6-month active lesions was 28% (11-66%) and 45% (18-115%), respectively. Assuming a 20-40% treatment-related reduction in NfL levels, 143-28 patients per arm will be required.

Conclusions

Blood NfL may qualify as an informative and easy-to-measure endpoint for future Phase 2 clinical studies that captures both inflammatory- and noninflammatory-driven neuroaxonal injury in RRMS.

Profiling individual clinical responses by high-frequency serum neurofilament assessment in MS

Objective

To evaluate individual neurofilament light chain (NfL) variation over the time of disease course and the potential of NfL measurement to predict treatment response in patients with MS.

Methods

We investigated 15 patients with MS after immune reconstitution treatment with alemtuzumab (ATZ). Monthly serum NfL (sNFL) measurements were correlated with Expanded Disability Status Scale (EDSS), MRI, and relapse activity over an observational period of up to 102 months.

Results

Before ATZ, sNfL was significantly increased in correlation with previous relapse/MRI activity. After ATZ, sNfL decreased quickly within the first 6 months. In patients classified as NEDA-3, sNfL declined and persisted at an individual low steady-state level of <8 pg/mL. During follow-up, 34 sNfL peaks with a >20 fold increase could be detected, which were associated with clinical or MRI disease activity. Even patient-reported relapse-suspicious symptoms, which have not been confirmed because relapses were accompanied by sNfL, increase, proposing sNfL assessment as a marker for relapse activity. sNfL started to increase earliest 5 months before, peaked at clinical onset, and recovered within 4–5 months. sNfL presented at higher levels in active patients requiring ATZ retreatment compared with responder patients. During 2 documented pregnancies, sNfL was at a low level, whereas a postpartum transient sNfL increase was seen without any signs of activity.

Conclusions

This study applied a long-term high-frequency sNfL assessment in an ATZ-treated cohort, allowing a holistic profiling on the individual level and highlighted that sNfL can eminently complement the individual clinical and MRI monitoring in clinical practice.

Neurofilament Light Chain as a Biomarker in Multiple Sclerosis

Due to the unpredictable course and heterogenous treatment response in multiple sclerosis (MS), there is a clear need for biomarkers that reflect disease activity in the clinical follow-up of these patients. Neurofilaments are neuron-specific components of the cytoskeleton that can be assayed in different body compartments. They have been explored as potential biomarkers for many years. Neurofilament light chain (NF-L) appears the most promising biomarker in MS patients, and there is now little doubt that NF-L should have a role in the follow-up of MS patients. Newer assays and techniques for NF-L detection available in serum samples confirms the usefulness of NF-L as a biomarker. Nevertheless, there is still a need for prospective studies, and studies to determine clinical useful cut-off values. This review evaluates the strengths and weaknesses of NF-L as a biomarker in patients with MS.

Longitudinal analysis of serum neurofilament light chain: A potential therapeutic monitoring biomarker for multiple sclerosis

Objectives:

Serum neurofilament light chain (sNfL) has been proposed a potential biomarker in multiple sclerosis (MS) based on mainly cross-sectional observations in Western population. To clarify clinical implication of sNfL, we longitudinally analysed sNfL levels at multiple time points in Korean MS patients undergoing alemtuzumab therapy.

Methods:

Between 2016 and 2018, 144 sera from 17 MS patients treated with alemtuzumab at National Cancer Centre and 35 sera from 35 age- and gender-matched healthy controls (HCs) were collected for a longitudinal study with a mean 21-month follow-up. The sera were measured for sNfL levels using single molecule array. Patients were classified into two groups: evidence of disease activity (EDA) or no evidence of disease activity (NEDA).

Results:

During alemtuzumab therapy, sNfL levels in EDA patients were significantly higher than those in NEDA patients and HCs ( p < 0.001). In longitudinal analysis, the sNfL levels were consistently low in NEDA patients, while it consistently increased in radiologically and/or clinically active status in EDA patients. All sNfL levels in radiologically and/or clinically active status samples were higher than those in inactive status samples.

Conclusion:

These results suggest that sNfL is a promising monitoring biomarker for personalized therapeutics in MS patients.

Increased cerebrospinal fluid neurofilament light chain in central nervous system inflammatory demyelinating disease

BACKGROUND

Central nervous system (CNS) inflammatory demyelinating disease (IDD) is an immune-mediated disease that is pathologically characterized by demyelination and inflammatory infiltration in the CNS and includes clinically isolated syndrome (CIS), multiple sclerosis (MS), and neuromyelitis optica spectrum disorders (NMOSD). IDD is usually characterized by variable symptoms, multivariate imaging, uncertain reactions to treatment, and a variable prognosis, which makes it difficult to diagnose early. In recent years, the role of the neurofilament light chain (NFL), an axonal injury biomarker, in IDD has become increasingly important. We will detect and analyse cerebrospinal fluid (CSF) NFL levels in IDD and normal control patients to determine the significance of NFL in the diagnosis and prognostic prediction of IDD.

METHODS

A total of 41 CIS, 34 MS and 73 NMOSD patients and 40 other patients with conditions such as neurosis and migraine with lumbar puncture were enrolled as the patient groups and the normal control (NC) group from the population of in- and outpatients of the Department of Neurology of the Sixth Medical Centre of Chinese People's Liberation Army General Hospital from January 2014 to October 2016. Clinical and neuroimaging features of the patient groups as well as CSF samples from both types of groups were collected, and the NFL levels of CSF were measured by enzyme linked immunosorbent assay.

RESULTS

CSF NFL levels in the CIS, MS and NMOSD groups were significantly higher than those in the NC group (P < 0.05, analysis of variance of NFL levels was performed after logarithmic transformation based on 10). There were no statistically significant differences in the CSF NFL levels among the CIS, MS and NMOSD groups (P > 0.05). The NFL levels of CSF in the CIS, MS and NMOSD groups were correlated with the expanded disability status scale score and enhancement in gadolinium-magnetic resonance imaging (all P < 0.05). Gender, oligoclonal band in CSF, aquaporin 4 antibody and 25‑hydroxy vitamin D₃ [25(OH)D₃] in serum were not related to the NFL levels (P > 0.05).

CONCLUSION

The NFL level of CSF is conducive to assessing the severity and probable progress of IDD but is not helpful in distinguishing IDD among Chinese.

Serum neurofilament dynamics predicts neurodegeneration and clinical progression in presymptomatic Alzheimer's disease

Neurofilament light chain (NfL) is a promising fluid biomarker of disease progression for various cerebral proteopathies. Here we leverage the unique characteristics of the Dominantly Inherited Alzheimer Network and ultrasensitive immunoassay technology to demonstrate that NfL levels in the cerebrospinal fluid (n = 187) and serum (n = 405) are correlated with one another and are elevated at the presymptomatic stages of familial Alzheimer's disease. Longitudinal, within-person analysis of serum NfL dynamics (n = 196) confirmed this elevation and further revealed that the rate of change of serum NfL could discriminate mutation carriers from non-mutation carriers almost a decade earlier than cross-sectional absolute NfL levels (that is, 16.2 versus 6.8 years before the estimated symptom onset). Serum NfL rate of change peaked in participants converting from the presymptomatic to the symptomatic stage and was associated with cortical thinning assessed by magnetic resonance imaging, but less so with amyloid-β deposition or glucose metabolism (assessed by positron emission tomography). Serum NfL was predictive for both the rate of cortical thinning and cognitive changes assessed by the Mini-Mental State Examination and Logical Memory test. Thus, NfL dynamics in serum predict disease progression and brain neurodegeneration at the early presymptomatic stages of familial Alzheimer's disease, which supports its potential utility as a clinically useful biomarker.

Contactin-1 and contactin-2 in cerebrospinal fluid as potential biomarkers for axonal domain dysfunction in multiple sclerosis

Background

Contactin-1 and contactin-2 are important for the maintenance of axonal integrity.

Objective

To investigate the cerebrospinal fluid levels of contactin-1 and contactin-2 in multiple sclerosis patients and controls, and their potential use as prognostic markers for neurodegeneration.

Methods

Cerebrospinal fluid contactin-1 and contactin-2 were measured in relapsing–remitting multiple sclerosis (n = 41), secondary progressive multiple sclerosis (n = 26) and primary progressive multiple sclerosis patients (n = 13) and controls (n = 18), and in a second cohort with clinically isolated syndrome patients (n = 88, median clinical follow-up period of 2.3 years) and controls (n = 20). Correlations/linear regressions were analysed with other baseline cerebrospinal fluid axonal damage markers and cross-sectional/longitudinal magnetic resonance imaging features.

Results

Contactin-1 and contactin-2 levels were up to 1.4-fold reduced in relapsing–remitting multiple sclerosis (contactin-1: p = 0.01, contactin-2: p = 0.02) and secondary progressive multiple sclerosis (contactin-1: p = 0.05, contactin-2: p = 0.02) compared to controls. In clinically isolated syndrome patients, contactin-1 tended to increase when compared to controls (p = 0.07). Both contactin-1 and contactin-2 correlated with neurofilament light, neurofilament heavy and magnetic resonance imaging metrics differently depending on the disease stage. In clinically isolated syndrome patients, baseline contactin-2 level (β = –0.42, p = 0.04) predicted the longitudinal decline in cortex volume.

Conclusion

Cerebrospinal fluid contactin-1 and contactin-2 reveal axonal dysfunction in various stages of multiple sclerosis and their inclusion to the biomarker panel may provide better insight into the extent of axonal damage/dysfunction.

CSF-Progranulin and Neurofilament Light Chain Levels in Patients With Radiologically Isolated Syndrome-Sign of Inflammation

Background: Cerebrospinal fluid (CSF) markers of disease in patients with radiologically isolated syndrome (RIS) are the subject of intense investigation, because they have the potential to enhance our understanding of the natural disease course and provide insights into similarities and differences between RIS and other multiple sclerosis (MS) disease identities.

Methods: Here we compared neurofilament light chain (NFL) and progranulin (PGRN) levels in the CSF in RIS patients with levels in patients with different subtypes of MS and healthy controls (HC) using Kruskal–Wallis one-way analysis of variance.

Results: Median CSF NFL concentrations in RIS patients did not differ to those in HC and clinically isolated syndrome (CIS) patients, but were significantly lower than in relapsing remitting (RRMS) and primary progressive (PPMS) MS patients. In contrast, RIS patients exhibited higher median CSF PGRN levels than HC and showed no significant differences compared with CIS, RRMS, and PPMS cases.

Conclusion: We postulate that elevated PGRN values in the CSF of RIS patients might indicate inflammatory and repair activity prior to axonal disintegration.

CSF Neurofilament Light Chain Levels in Primary Progressive MS: Signs of Axonal Neurodegeneration

Objectives: Elevated neurofilament light chain (NFL) levels within the cerebrospinal fluid (CSF) are a biomarker representing axonal neurodegeneration in rapid progressive neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). It is unclear to what extent the levels of NFL increase in the CSF (CSF-NFL) in a chronic neuroinflammatory process with axonal neurodegeneration, as found in primary progressive multiple sclerosis (PPMS).

Methods: We used a multicenter approach to statistically compare CSF-NFL levels between PPMS patients (n = 50), ALS patients (n = 50), and healthy controls (n = 50). Clinical findings, including disease duration, expanded disability status scale (EDSS), electrophysiological recordings such as visual evoked potentials or spinal and cerebral MRI, and previously administered treatment were selected as experimental parameters retrospectively.

Results: Median [range] CSF-NFL concentrations in PPMS patients were significantly higher than in the controls [1724 (799–4275) pg/ml vs. 1202 (612–2934) pg/ml, p = 0.015], and significantly lower compared to ALS patients [1724 (799–4275) pg/ml vs. 10238 (2610–35138) pg/ml, p < 0.001]. There was no correlation between CSF-NFL and disease duration (p = 0.5), EDSS (p = 0.2) or treatment (p = 0.3).

Conclusion: We conclude that CSF-NFL may mirror the proposed slow axonal degeneration in PPMS, but does not reflect the disease severity.

Cerebrospinal fluid immunoglobulin light chain ratios predict disease progression in multiple sclerosis

OBJECTIVE

To determine whether the ratio of cerebrospinal fluid (CSF) immunoglobulin kappa to lambda light chains at time of multiple sclerosis (MS) diagnosis predicts disease progression and whether this was intrinsic to CSF plasmablasts.

METHODS

CSF and peripheral blood were obtained from patients undergoing elective diagnostic lumbar puncture and included clinically isolated syndrome (CIS) (n=43), relapsing remitting MS (RRMS; n=50), primary progressive MS (PPMS; n=20) and other neurological disease controls, both inflammatory (ONID; n=23) and non-inflammatory (OND; n=114). CSF samples were assayed for free and immunoglobulin-associated light chains and on B cells and plasmablasts. Clinical follow-up data were collected during a 5-year follow-up period where available.

RESULTS

There was an increased median CSF κ:λ free light chain (FLC) in all MS groups (CIS: 18.2, 95% CI 6.8 to 30.3; RRMS: 4.4, 95% CI 2.7 to 11.4; PPMS: 12.0, 95% CI 3.6 to 37.1) but not controls (OND: 1.61, 95% CI 1.4 to 1.9; ONID: 1.7, 95% CI 1.3 to 2.2; p<0.001). This ratio predicted Expanded Disability Status Scores (EDSS) progression at 5 years, with a lower median EDSS in the group with high (>10) CSF κ:λ FLC (0.0, 95% CI 0 to 2.5 vs 2.5, 95% CI 0 to 4, high vs low; p=0.049). CSF κ:λ FLC correlated with CSF IgG1 κ:λ (r=0.776; p<0.0001) and was intrinsic to CSF plasmablasts (r=0.65; p=0.026).

CONCLUSIONS

These data demonstrate that CSF immunoglobulin κ:λ ratios, determined at the time of diagnostic lumbar puncture, predict MS disease progression and may therefore be useful prognostic markers for early therapeutic stratification.

Biomarkers of Neurodegeneration in Autoimmune-Mediated Encephalitis

Progranulin (PGRN), Total-Tau (t-tau), and Neurofilament light chain (NfL) are well known biomarkers of neurodegeneration. The objective of the present study was to investigate whether these parameters represent also biomarkers in autoimmune-mediated Encephalitis (AE) and may give us insights into the pathomechanisms of AE. We retrospectively examined the concentration of PGRN in the cerebrospinal fluid (CSF) and serum of 38 patients suffering from AE in acute phase and/or under treatment. This AE cohort comprises patients with autoantibodies against: NMDAR (n = 18 patients), Caspr2 (n = 8), Lgi-1 (n = 10), GABAB(R) (n = 1), and AMPAR (n = 1). Additionally, the concentrations of NfL (n = 25) and t-tau (n = 13) in CSF were measured when possible. Follow up data including MRI were available in 13 patients. Several age-matched cohorts with neurological diseases besides neuroinflammation or neurodegeneration served as control groups. We observed that PGRN was significantly elevated in the CSF of patients with NMDAR-AE in the acute phase, but normalized at follow up under treatment (p < 0.01). In the CSF of other patients with AE PGRN was in the range of the CSF levels of control groups. T-tau was highly elevated in the CSF of patients with temporal FLAIR-signal in the MRI and in patients developing a hippocampal sclerosis. NfL was exceptionally high initially in Patients with AE with a paraneoplastic or parainfectious cause and also normalized under treatment. The normalizations of all biomarkers were mirrored in an improvement on the modified Rankin scale. The data suggest that the concentration of PGRN in CSF might be a biomarker for acute NMDAR-AE. Pathological high t-tau levels may indicate a risk for hippocampal sclerosis. The biomarker properties of NfL remain unclear since the levels decrease under treatment, but it could not predict severity of disease in this small cohort. According to our results, we recommend to measure in clinical practice PGRN and t-tau in the CSF of patients with AE.

Neurofilament light chain as a biological marker for multiple sclerosis: a meta-analysis study

PURPOSE

There is a need for biomarkers in multiple sclerosis (MS) to make an early diagnosis and monitor its progression. This study was designed to evaluate the value of neurofilament light (NFL) chain levels as cerebrospinal fluid (CSF) or blood biomarker in patients with MS by using a quantitative meta-analysis.

METHODS

The PubMed, Embase, and Web of Science databases were systematically searched for relevant studies. Articles in English that evaluated the utility of NFL in CSF and blood in the diagnosis of MS were included. Data were extracted by two independent researchers. Mean (± SD) NFL concentration for MS patients and control subjects were extracted. Review Manager version 5.3 software with a continuous-variable random-effects model was used to summarize the diagnostic indexes from eligible studies. The Newcastle-Ottawa Scale was used for assessing the quality and risk of bias of included studies. In addition, subgroup analysis and meta-regression were performed to assess potential heterogeneity sources.

RESULTS

The meta-analysis included 13 articles containing results from 15 studies. A total of 10 studies measured NFL levels in CSF and five studies measured NFL levels in blood. Data were available on 795 participants in CSF and 1,856 participants in blood. Moreover, CSF NFL in MS patients was higher than that in healthy control groups (pooled standard mean difference [Std.MD]=0.88, 95% CI [0.50, 1.26], P<0.00001) and serum NFL in MS patients was higher than that in control subjects (pooled Std.MD=0.47, 95% CI [0.24, 0.71], P<0.0001).

CONCLUSION

NFL chain has significantly increased in MS patients, which substantially strengthens the clinical evidence of the NFL in MS. The NFL may be used as a prognostic biomarker to monitor disease progression, disease activity, and treatment efficacy in the future.

Prognostic value of cerebrospinal fluid neurofilament light chain and chitinase-3-like-1 in newly diagnosed patients with multiple sclerosis

BACKGROUND

Neurofilament light chain (NFL) and chitinase-3-like-1 (CHI3L1) concentrations in cerebrospinal fluid (CSF) may have prognostic value in clinically isolated syndromes (CIS) and relapsing-remitting multiple sclerosis (RRMS).

OBJECTIVES

To compare the prognostic value of CSF concentrations of NFL and CHI3L1 in newly diagnosed CIS and RRMS patients.

METHODS

NFL and CHI3L1 were measured in CSF in 177 newly diagnosed patients with CIS or RRMS who were followed clinically for a mean of 5.7 years.

RESULTS

At baseline CSF concentrations of NFL correlated with CSF concentrations of CHI3L1, relapses in the previous year, time from last relapse, and the Expanded Disability Status Scale (EDSS) score. CSF concentrations of NFL and CHI3L1 were both associated with increased relapse risk during the first 2 years in univariate analyses, but only the CSF concentration of NFL was independently associated with relapse risk in a multivariable analysis. There was no relationship between CSF concentrations of NFL or CHI3L1 and risk of conversion to secondary progressive MS or development of disability.

CONCLUSION

CSF concentrations of NFL are associated with 2-year relapse risk but not with disease progression or clinical worsening in newly diagnosed CIS and RRMS patients. This may be due to confounding by the effect of disease-modifying therapies.

Neurofilaments and 10-year follow-up in multiple sclerosis

BACKGROUND

The role of biomarkers to predict clinical outcome in multiple sclerosis (MS) is still debated.

OBJECTIVE

To test whether cerebrospinal fluid (CSF) light-chain neurofilament (NfL) levels in newly diagnosed patients with MS could predict clinical outcome over a 10-year period.

METHODS

Patients with newly diagnosed MS underwent standardized clinical assessments at baseline and 5 and 10 years of follow-up. Expanded Disability Status Scale (EDSS) progression between assessments was defined as an increase in one point or more if <6 and 0.5 or more if ≥6. CSF obtained at baseline was analyzed for levels of NfL using enzyme-linked immunosorbent assay technology.

RESULTS

A total of 44 patients were included. In all, 35 patients (80%) had relapsing-remitting multiple sclerosis (RRMS). Patients who progressed in EDSS showed a trend for higher median baseline CSF-NfL levels than patients who did not progress after 5 years (947 ng/L vs 246 ng/L, p = 0.05), and although not statistically significant, after 10 years (708 ng/L vs 265 ng/L, p = 0.28). Patients who converted from RRMS to secondary-progressive multiple sclerosis (SPMS) at 5 years had a statistical significant higher median CSF level of NfL (2122 ng/L vs 246 ng/L, p = 0.01).

CONCLUSION

CSF levels of NfL at the time of diagnosis seems to be an early predictive biomarker of long-term clinical outcome and conversion from RRMS to SPMS.

Serum Neurofilament Light Chain Levels Are Related to Small Vessel Disease Burden

Background and Purpose

Neurofilament light chain (NfL) is a blood marker for neuroaxonal damage. We assessed the association between serum NfL and cerebral small vessel disease (SVD), which is highly prevalent in elderly individuals and a major cause of stroke and vascular cognitive impairment.

Methods

Using a cross-sectional design, we studied 53 and 439 patients with genetically defined SVD (Cerebral Autosomal-Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy [CADASIL]) and sporadic SVD, respectively, as well as 93 healthy controls. Serum NfL was measured by an ultrasensitive single-molecule array assay. We quantified magnetic resonance imaging (MRI) markers of SVD, i.e., white matter hyperintensity volume, lacune volume, brain volume, microbleed count, and mean diffusivity obtained from diffusion tensor imaging. Clinical characterization included neuropsychological testing in both SVD samples. CADASIL patients were further characterized for focal neurological deficits (National Institutes of Health stroke scale [NIHSS]) and disability (modified Rankin scale [mRS]).

Results

Serum NfL levels were elevated in both SVD samples (P<1e-05 compared with controls) and associated with all SVD MRI markers. The strongest association was found for mean diffusivity (CADASIL, R²=0.52, P=1.2e-09; sporadic SVD, R²=0.21, P<1e-15). Serum NfL levels were independently related to processing speed performance (CADASIL, R²=0.27, P=7.6e-05; sporadic SVD, R²=0.06, P=4.8e-08), focal neurological symptoms (CADASIL, NIHSS, P=4.2e-05) and disability (CADASIL, mRS, P=3.0e-06).

Conclusions

We found serum NfL levels to be associated with both imaging and clinical features of SVD. Serum NfL might complement MRI markers in assessing SVD burden. Importantly, SVD needs to be considered when interpreting serum NfL levels in the context of other age-related diseases.

Multiple sclerosis biomarkers: Helping the diagnosis?

Multiple sclerosis (MS) is a complex heterogeneous disease. Diagnostic criteria are based on symptoms, biomarkers, MRI data and exclusion of differential diagnoses. Over the past few years, the usefulness of biomarkers has progressively decreased with the development of new MRI criteria, yet dozens of new biomarkers, especially in cerebrospinal fluid, for MS diagnosis and prognosis have been described. Large-scale studies validating some of these new biomarkers have also provided confirmation of a restricted set of biomarkers (presented here in this review) as having potential value for different stages of the disease, including as early as clinically isolated syndrome and radiologically isolated syndrome. However, differentiating progressive forms of MS from relapsing-remitting MS remains a genuine challenge, and could help to predict future conversion to secondary-progressive MS. In addition, new approaches combining multiple biomarkers might allow us to unravel the complexity of the disease and determine disease stages more precisely. Moreover, recent technological developments allowing analysis of biomarkers in plasma have also provided less invasive analysis of MS, and should serve to predict MS evolution and therapeutic responses during follow-up.

Neurofilament as Neuronal Injury Blood Marker in Preeclampsia

Preeclampsia has been shown to be associated with changes in cerebral structure and cognitive function later in life. Nf (neurofilaments) are specific scaffolding proteins of neurons, and their quantification in serum has been proposed as a biomarker for neuroaxonal injury. We performed a prospective, longitudinal, single-center study at the University Hospital of Basel to determine serum Nf concentrations in pregnant women with singleton pregnancies and with high risk of preeclampsia or with early signs of preeclampsia. Enrollment started at 21 weeks of gestation, followed up with multiple visits until delivery. Sixty out of 197 women developed preeclampsia (30.5%). NfL (Nf light chain) was measured with a highly sensitive single molecule array (Simoa) assay, in addition to the established preeclampsia markers sFlt-1 (soluble fms-like tyrosine kinase-1) and PlGF (placental growth factor). The most important independent predictors of NfL were maternal age, number of pregnancies, and proteinuria. NfL levels increased during pregnancy and were significantly higher in women developing preeclampsia. The discriminatory accuracy of NfL, PlGF, and sFlt-1 in receiver operating characteristic curves analysis (area under the curve) of the overall group was 0.68, 0.81, and 0.84, respectively, and in women older than 36 years 0.7, 0.62, and 0.79, respectively. We conclude that increased axonal injury serum marker NfL predicts preeclampsia particularly in older women, with an accuracy similar to the established angiogenic factors. NfL may serve as an early indicator of preeclampsia-induced changes in cerebral structure and may help to stratify disease management.

A new enzyme-linked immunosorbent assay for neurofilament light in cerebrospinal fluid: analytical validation and clinical evaluation

Background

Cerebrospinal fluid (CSF) neurofilament light (NfL) is a reliable marker of neuro-axonal damage in different neurological disorders that is related to disease severity. To date, all recent studies performed in human CSF have used the same enzyme-linked immunosorbent assay (ELISA). To confirm the large body of evidence for NfL, we developed a new ELISA method and here we present the performance characteristics of this new ELISA for CSF NfL in different neurological disorders.

Methods

We produced two monoclonal antibodies (NfL21 and NfL23) directed against the NfL core domain, and developed a novel sandwich ELISA method that we evaluated in patients with: 1) inflammatory demyelinating diseases (IDD; n = 97), including multiple sclerosis (MS; n = 59), clinically isolated syndrome (CIS; n = 32), and radiologically isolated syndrome (RIS; n = 6); 2) Alzheimer’s disease (AD; n = 72), including mild cognitive impairment due to AD (MCI-AD, n = 36) and probable AD dementia (AD-dem; n = 36); 3) Parkinson’s disease (PD; n = 30); and 4) other neurological noninflammatory and non-neurodegenerative diseases (OND; n = 30).

Results

Our new NfL ELISA showed a good analytical performance (inter-plate coefficient of variation (CV) < 13%), with no cross-reactivity with neurofilament medium and heavy (NfM and NfH). With respect to the other available ELISAs, CSF NfL showed the same range of values with a strong correlation (r = 0.9984, p < 0.001) between the two methods. CSF NfL levels were significantly higher in MCI-AD/AD-dem and IDD patients as compared with both PD and OND patients. The highest discriminative power was obtained between IDD and OND patients (area under the curve (AUC) 0.87, 95% confidence interval (CI) 0.80–0.95). Within the IDD group, CSF NfL positively correlated with several clinical and radiological disease severity parameters.

Conclusions

These results show a good analytical performance of the new ELISA for quantification of NfL concentrations in the CSF. CSF NfL is confirmed to be a reliable marker in AD and MS, and a disease-severity marker in MS patients.

The role of blood and CSF biomarkers in the evaluation of new treatments against multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is an immune-mediated chronic neurodegenerative disease of the central nervous system (CNS). Therapeutic interventions with immunomodulatory agents reduce disease activity and disability development, which are monitored clinically and by magnetic resonance imaging (MRI). However, these measures largely lack information on the impact from these therapies on inflammation, demyelination and axonal injury, the essential pathophysiological features of MS. Several biomarkers for inflammation and neurodegeneration have been detected in cerebrospinal fluid (CSF). In MS, some of these biomarkers seem to reflect disease activity, disability progression, and therapeutic response. Areas covered: In this review, we describe the most promising CSF biomarkers of inflammation and degeneration for monitoring therapeutic interventions in MS. We also describe the evolution of highly sensitive immunoassays that enable determination of neuron-specific biomarkers in blood. Expert commentary: Together with clinical and MRI measures, CSF biomarkers may improve the assessment of therapeutic efficacy and make personalized treatment possible. One disadvantage has been the need of repetitive lumbar punctures to obtain CSF. However, the technical development of highly sensitive immunoassays allows determination of extremely low quantities of neuron-specific proteins in blood. This will potentially open a new era for monitoring disease activity and treatment response in MS.

Serum neurofilament light is sensitive to active cerebral small vessel disease

OBJECTIVE

To explore whether serum neurofilament light chain protein (NfL) levels are increased in patients with MRI-confirmed recent small subcortical infarcts (RSSI) compared to healthy controls and to determine the subsequent course and determinants of NfL levels in a longitudinal manner.

METHODS

In a prospectively collected group of symptomatic patients with an RSSI (n = 79, mean age 61 ± 11 years, 67% male), we analyzed brain MRI and serum NfL using a Single Molecule Array (Simoa) assay at baseline and at 3 and 15 months after stroke. Community-dwelling healthy age- and sex-matched individuals with comparable severity of MRI white matter hyperintensities (WMH) (n = 53) served as controls.

RESULTS

Patients with an RSSI had higher NfL baseline levels compared to controls (73.45 vs 34.59 pg/mL, p < 0.0001), and they were increasingly higher with the time from stroke symptom onset to blood sampling (median 4 days, range 1-11 days, r_s = 0.51, p < 0.0001). NfL levels remained increased at the 3-month follow-up but returned to normal at 15 months after stroke. NfL levels were associated with RSSI size and baseline WMH severity and were especially high in patients with new, clinically silent cerebral small vessel disease (CSVD)-related lesions at follow-up.

CONCLUSIONS

Serum NfL is increased in patients with an RSSI and the occurrence of new CSVD-related MRI lesions, even when clinically silent. This suggests NfL as a blood biomarker for active CSVD.

Fluid biomarker and electrophysiological outcome measures for progressive MS trials

Progressive multiple sclerosis (MS) is characterized by insidious clinical worsening that is difficult to accurately quantify and predict. Biofluid markers and electrophysiological measures are potential candidate outcome measures in clinical trials, allowing the quantification of nervous damage occurring in the disease. Neurofilaments are highly specific neuronal proteins. They may have come closest to such applications by their higher concentrations repeatedly demonstrated in cerebrospinal fluid (CSF) in all stages of MS, during relapses, their responsiveness to disease-modifying treatments in relapsing and progressive MS and their associations with measures of inflammatory and degenerative magnetic resonance imaging (MRI) outcomes. Digital single-molecule array (Simoa) technology improves accuracy of bioassays in the quantification of neurofilament light chain (NfL) in serum and plasma. NfL seems to mark a common final path of neuroaxonal injury independent of specific causal pathways. CSF and blood levels of NfL are highly correlated across various diseases including MS, suggesting that blood measurements may be useful in assessing response to treatment and predicting future disease activity. Other biomarkers like matrix metalloproteinases, chemokines, or neurotrophic factors have not been studied to a similar extent. Such measures, especially in blood, need further validation to enter the trial arena or clinical practice. The broadening armamentarium of highly sensitive assay technologies in the future may shed even more light on patient heterogeneity and mechanisms leading to disability in MS. Evoked potentials (EPs) are used in clinical practice to measure central conduction of central sensorimotor pathways. They correlate with and predict the severity of clinical involvement of their corresponding function. Their validation for use in multicenter studies is still lacking, with the exception of visual EPs. If further validated, EPs and fluid biomarkers would represent useful outcome measures for clinical trials, being related to specific mechanisms of the ongoing pathologic changes.

Proteomic studies in the discovery of cerebrospinal fluid biomarkers for amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a progressive degenerative motor neuron disease, which usually leads to death within a few years. The diagnosis is mainly based on clinical symptoms and there is a need for ALS-specific biomarkers to make an early and precise diagnosis, for development of disease-modifying drugs and to gain new insights into pathophysiology. Areas covered: In the present review, we summarize studies using mass spectrometric (MS) approaches to identify protein alterations in the cerebrospinal fluid (CSF) of ALS patients. In total, we identified 11 studies fulfilling our criteria by searching in the PubMed database using the keywords 'ALS' and 'CSF' combined with 'proteome', 'proteomic', 'mass spectrometry' or 'protein biomarker'. Ten proteins were differently regulated in ALS CSF compared to controls in at least 2 studies. We will discuss the relevance of the identified proteins regarding the frequency of identification, extent of alteration and brain-specificity. Expert commentary: Most of the identified CSF biomarker candidates are irreproducible or mainly blood-derived. We assign the missing success of CSF proteomic studies in biomarker discovery to a lack of sensitivity, unsuitable normalization, low quality assurance and variations originating from sample preparation. These issues must be improved in future proteomic studies in CSF.

Serum Neurofilament light: A biomarker of neuronal damage in multiple sclerosis

Objective

Neurofilament light chains (NfL) are unique to neuronal cells, are shed to the cerebrospinal fluid (CSF), and are detectable at low concentrations in peripheral blood. Various diseases causing neuronal damage have resulted in elevated CSF concentrations. We explored the value of an ultrasensitive single‐molecule array (Simoa) serum NfL (sNfL) assay in multiple sclerosis (MS).

Methods

sNfL levels were measured in healthy controls (HC, n = 254) and two independent MS cohorts: (1) cross‐sectional with paired serum and CSF samples (n = 142), and (2) longitudinal with repeated serum sampling (n = 246, median follow‐up = 3.1 years, interquartile range [IQR] = 2.0–4.0). We assessed their relation to concurrent clinical, imaging, and treatment parameters and to future clinical outcomes.

Results

sNfL levels were higher in both MS cohorts than in HC (p < 0.001). We found a strong association between CSF NfL and sNfL (β = 0.589, p < 0.001). Patients with either brain or spinal (43.4pg/ml, IQR = 25.2–65.3) or both brain and spinal gadolinium‐enhancing lesions (62.5pg/ml, IQR = 42.7–71.4) had higher sNfL than those without (29.6pg/ml, IQR = 20.9–41.8; β = 1.461, p = 0.005 and β = 1.902, p = 0.002, respectively). sNfL was independently associated with Expanded Disability Status Scale (EDSS) assessments (β = 1.105, p < 0.001) and presence of relapses (β = 1.430, p < 0.001). sNfL levels were lower under disease‐modifying treatment (β = 0.818, p = 0.003). Patients with sNfL levels above the 80th, 90th, 95th, 97.5th, and 99th HC‐based percentiles had higher risk of relapses (97.5th percentile: incidence rate ratio = 1.94, 95% confidence interval [CI] = 1.21–3.10, p = 0.006) and EDSS worsening (97.5th percentile: OR = 2.41, 95% CI = 1.07–5.42, p = 0.034).

Interpretation

These results support the value of sNfL as a sensitive and clinically meaningful blood biomarker to monitor tissue damage and the effects of therapies in MS. Ann Neurol 2017;81:857–870

Plasma neurofilament light chain levels in patients with MS switching from injectable therapies to fingolimod

Background:

Neurofilament light chain (NFL) is a cerebrospinal fluid (CSF) marker of neuroaxonal damage in multiple sclerosis (MS).

Objective:

To determine the correlation of NFL in CSF and serum/plasma, and in plasma after switching from injectable MS therapies to fingolimod.

Methods:

A first cohort consisted of MS patients ( n = 39) and neurological disease controls ( n = 27) where CSF and plasma/serum had been collected for diagnostic purposes. A second cohort ( n = 243) consisted of patients from a post-marketing study of fingolimod. NFL was determined with Single Molecule Array (Simoa™) technology (detection threshold 1.95 pg/mL).

Results:

Mean NFL pg/mL (standard deviation ( SD)) was 341 (267) and 1475 (2358) in CSF and 8.2 (3.58) and 17.0 (16.94) in serum from controls and MS, respectively. CSF/serum and plasma/serum levels were highly correlated ( n  = 66, rho  = 0.672, p  < 0.0001 and n  = 16, rho  = 0.684, p  = 0.009, respectively). In patients starting fingolimod ( n = 243), mean NFL pg/mL ( SD) in plasma was reduced between baseline (20.4 (10.7)) and at 12 months (13.5 (7.3), p < 3 × 10−6), and levels remained stable at 24 months (13.2 (6.2)).

Conclusion:

NFL in serum and CSF are highly correlated and plasma NFL levels decrease after switching to highly effective MS therapy. Blood NFL measurement can be considered as a biomarker for MS therapy response.

Neurofilament light chain in cerebrospinal fluid and prediction of disease activity in clinically isolated syndrome and relapsing-remitting multiple sclerosis

BACKGROUND AND PURPOSE

Improved biomarkers are needed to facilitate clinical decision-making and as surrogate endpoints in clinical trials in multiple sclerosis (MS). We assessed whether neurodegenerative and neuroinflammatory markers in cerebrospinal fluid (CSF) at initial sampling could predict disease activity during 2 years of follow-up in patients with clinically isolated syndrome (CIS) and relapsing-remitting MS.

METHODS

Using multiplex bead array and enzyme-linked immunosorbent assay, CXCL1, CXCL8, CXCL10, CXCL13, CCL20, CCL22, neurofilament light chain (NFL), neurofilament heavy chain, glial fibrillary acidic protein, chitinase-3-like-1, matrix metalloproteinase-9 and osteopontin were analysed in CSF from 41 patients with CIS or relapsing-remitting MS and 22 healthy controls. Disease activity (relapses, magnetic resonance imaging activity or disability worsening) in patients was recorded during 2 years of follow-up in this prospective longitudinal cohort study.

RESULTS

In a logistic regression analysis model, NFL in CSF at baseline emerged as the best predictive marker, correctly classifying 93% of patients who showed evidence of disease activity during 2 years of follow-up and 67% of patients who did not, with an overall proportion of 85% (33 of 39 patients) correctly classified. Combining NFL with either neurofilament heavy chain or osteopontin resulted in 87% overall correctly classified patients, whereas combining NFL with a chemokine did not improve results.

CONCLUSIONS

This study demonstrates the potential prognostic value of NFL in baseline CSF in CIS and relapsing-remitting MS and supports its use as a predictive biomarker of disease activity.

Outcome Measures in Clinical Trials for Multiple Sclerosis

Due to the heterogeneous nature of the disease, it is a challenge to capture disease activity of multiple sclerosis (MS) in a reliable and valid way. Therefore, it can be difficult to assess the true efficacy of interventions in clinical trials. In phase III trials in MS, the traditionally used primary clinical outcome measures are the Expanded Disability Status Scale and the relapse rate. Secondary outcome measures in these trials are the number or volume of T2 hyperintense lesions and gadolinium-enhancing T1 lesions on magnetic resonance imaging (MRI) of the brain. These secondary outcome measures are often primary outcome measures in phase II trials in MS. Despite several limitations, the traditional clinical measures are still the mainstay for assessing treatment efficacy. Newer and potentially valuable outcome measures increasingly used or explored in MS trials are, clinically, the MS Functional Composite and patient-reported outcome measures, and on MRI, brain atrophy and the formation of persisting black holes. Several limitations of these measures have been addressed and further improvements will probably be proposed. Major improvements are the coverage of additional functional domains such as cognitive functioning and assessment of the ability to carry out activities of daily living. The development of multidimensional measures is promising because these measures have the potential to cover the full extent of MS activity and progression. In this review, we provide an overview of the historical background and recent developments of outcome measures in MS trials. We discuss the advantages and limitations of various measures, including newer assessments such as optical coherence tomography, biomarkers in body fluids and the concept of 'no evidence of disease activity'.

[Cerebrospinal fluid diagnostics in multiple sclerosis]

As a chronic inflammatory disease of the central nervous system (CNS), multiple sclerosis (MS) is associated with characteristic abnormalities in cerebrospinal fluid (CSF). Thus, in addition to magnetic resonance imaging, CSF examination is a central diagnostic procedure in patients with MS, which can corroborate a diagnosis of MS and may also help to discern differential diagnoses. The most important CSF finding in MS is the detection of persistent polyspecific intrathecal immunoglobulin synthesis. This review summarizes CSF findings of patients with MS and addresses issues of relevance for clinical practice, potential diagnostic pitfalls as well as new developments in CSF diagnostics of MS.

Neurofilament light chain level is a weak risk factor for the development of MS

Objective:

To determine the prognostic value of selected biomarkers in clinically isolated syndromes (CIS) for conversion to multiple sclerosis (MS) and disability accrual.

Methods:

Data were acquired from 2 CIS cohorts. The screening phase evaluated patients developing clinically definite MS (CIS-CDMS) and patients who remained as CIS during a 2-year minimum follow-up (CIS-CIS). We determined levels of neurofascin, semaphorin 3A, fetuin A, glial fibrillary acidic protein, and neurofilament light (NfL) and heavy chains in CSF (estimated mean [95% confidence interval; CI]). We evaluated associations between biomarker levels, conversion, disability, and magnetic resonance parameters. In the replication phase, we determined NfL levels (n = 155) using a 900 ng/L cutoff. Primary endpoints in uni- and multivariate analyses were CDMS and 2010 McDonald MS.

Results:

The only biomarker showing significant differences in the screening was NfL (CIS-CDMS 1,553.1 [1,208.7–1,897.5] ng/L and CIS-CIS 499.0 [168.8–829.2] ng/L, p < 0.0001). The strongest associations were with brain parenchymal fraction change (r_s = −0.892) and percentage brain volume change (r_s = −0.842) at 5 years. NfL did not correlate with disability. In the replication phase, more NfL-positive patients, according to the cutoff, evolved to MS. Every 100-ng/L increase in NfL predicted CDMS (hazard ratio [HR] = 1.009, 95% CI 1.005–1.014) and McDonald MS (HR = 1.009, 95% CI 1.005–1.013), remaining significant for CDMS in the multivariate analysis (adjusted HR = 1.005, 95% CI 1.000–1.011). This risk was lower than the presence of oligoclonal bands or T2 lesions.

Conclusions:

NfL is a weak independent risk factor for MS. Its role as an axonal damage biomarker may be more relevant as suggested by its association with medium-term brain volume changes.

Secondary Progressive Multiple Sclerosis: Definition and Measurement

Secondary progressive multiple sclerosis (SPMS) is diagnosed retrospectively and involves a clinical course characterized by a progressive accumulation of neurological disability, independent of relapses, following an initial relapsing-remitting (RR) phase. Our incomplete understanding of the pathological mechanisms underlying neurodegeneration in multiple sclerosis (MS) may explain why, to date, there is no definitive imaging or laboratory test that is able to inform us when the disease is clearly entering into a progressive phase and why the vast majority of clinical trials testing immunosuppressant and immunomodulating drugs in SPMS patients has so far yielded disappointing or mixed results. Here we discuss the definition(s) of SPMS and how it may vary, outcome measurements (current and emerging) and modern trial design.

Serum neurofilament light chain levels are increased in patients with a clinically isolated syndrome

BACKGROUND

Neurofilament light chain (NfL) represents a promising biomarker for axonal injury. We present the first exploratory study on serum NfL in patients with a clinically isolated syndrome (CIS) and healthy controls.

METHODS

We investigated serum NfL levels in 100 patients with CIS with a short conversion interval to clinically definite multiple sclerosis (MS) (fast converters (FC), median (IQR) conversion time: 110 days (79-139)); 98 patients with non-converting CIS (non-converters (NC), follow-up: 6.5 years (5.3-7.9)); and 92 healthy controls.

RESULTS

NfL levels were higher in FC (24.1 pg/mL (13.5-51.8)) and NC (19.3 pg/mL (13.6-35.2)) than in healthy controls (7.9 pg/mL (5.6-17.2)) (OR=5.85; 95% CI 2.63 to 13.02; p = 1.5 × 10(-5) and OR = 7.03; 95% CI 2.85 to 17.34; p = 2.3 × 10(-5), respectively). When grouping FC and NC, increased serum NfL concentration was also associated with increasing numbers of T2 hyperintense MRI lesions (OR = 2.36; 95% CI 1.21 to 4.59; p = 0.011), gadolinium-enhancing lesions (OR = 2.69; 95% CI 1.13 to 6.41; p=0.026) and higher disability scores (OR = 2.54; 95% CI 1.21 to 5.31; p = 0.013) at CIS diagnosis.

CONCLUSIONS

If replicated in future studies, serum NfL may represent a reliable and easily accessible biomarker of early axonal damage in CIS and MS.

Serum neurofilament light chain in early relapsing remitting MS is increased and correlates with CSF levels and with MRI measures of disease severity

BACKGROUND/OBJECTIVES

Neurofilament light chain (NfL) levels in the cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients correlate with the degree of neuronal injury. To date, little is known about NfL concentrations in the serum of relapsing remitting multiple sclerosis (RRMS) patients and their relationship with CSF levels and magnetic resonance imaging (MRI) measures of disease severity. We aimed to validate the quantification of NfL in serum samples of RRMS, as a biofluid source easily accessible for longitudinal studies.

METHODS

A total of 31 RRMS patients underwent CSF and serum sampling. After a median time of 3.6 years, 19 of these RRMS patients, 10 newly recruited RRMS patients and 18 healthy controls had a 3T MRI and serum sampling. NfL concentrations were determined by electrochemiluminescence immunoassay.

RESULTS

NfL levels in serum were highly correlated to levels in CSF (r = 0.62, p = 0.0002). Concentrations in serum were higher in patients than in controls at baseline (p = 0.004) and follow-up (p = 0.0009) and did not change over time (p = 0.56). Serum NfL levels correlated with white matter (WM) lesion volume (r = 0.68, p < 0.0001), mean T1 (r = 0.40, p = 0.034) and T2* relaxation time (r = 0.49, p = 0.007) and with magnetization transfer ratio in normal appearing WM (r = -0.41, p = 0.029).

CONCLUSION

CSF and serum NfL levels were highly correlated, and serum concentrations were increased in RRMS. Serum NfL levels correlated with MRI markers of WM disease severity. Our findings further support longitudinal studies of serum NfL as a potential biomarker of on-going disease progression and as a potential surrogate to quantify effects of neuroprotective drugs in clinical trials.

Lipocalin-2 is increased in progressive multiple sclerosis and inhibits remyelination

Objective:

We aimed to examine the regulation of lipocalin-2 (LCN2) in multiple sclerosis (MS) and its potential functional relevance with regard to myelination and neurodegeneration.

Methods:

We determined LCN2 levels in 3 different studies: (1) in CSF and plasma from a case-control study comparing patients with MS (n = 147) with controls (n = 50) and patients with relapsing-remitting MS (n = 75) with patients with progressive MS (n = 72); (2) in CSF and brain tissue microdialysates from a case series of 7 patients with progressive MS; and (3) in CSF at baseline and 60 weeks after natalizumab treatment in a cohort study of 17 patients with progressive MS. Correlation to neurofilament light, a marker of neuroaxonal injury, was tested. The effect of LCN2 on myelination and neurodegeneration was studied in a rat in vitro neuroglial cell coculture model.

Results:

Intrathecal production of LCN2 was increased predominantly in patients with progressive MS (p < 0.005 vs relapsing-remitting MS) and displayed a positive correlation to neurofilament light (p = 0.005). Levels of LCN2 in brain microdialysates were severalfold higher than in the CSF, suggesting local production in progressive MS. Treatment with natalizumab in progressive MS reduced LCN2 levels an average of 13% (p < 0.0001). LCN2 was found to inhibit remyelination in a dose-dependent manner in vitro.

Conclusions:

LCN2 production is predominantly increased in progressive MS. Although this moderate increase does not support the use of LCN2 as a biomarker, the correlation to neurofilament light and the inhibitory effect on remyelination suggest that LCN2 might contribute to neurodegeneration through myelination-dependent pathways.

Therapeutic Advances and Future Prospects in Progressive Forms of Multiple Sclerosis

Identifying effective therapies for the treatment of progressive forms of multiple sclerosis (MS) is a highly relevant priority and one of the greatest challenges for the global MS community. Better understanding of the mechanisms involved in progression of the disease, novel trial designs, drug repurposing strategies, and new models of collaboration may assist in identifying effective therapies. In this review, we discuss various therapies under study in phase II or III trials, including antioxidants (idebenone); tyrosine kinase inhibitors (masitinib); sphingosine receptor modulators (siponimod); monoclonal antibodies (anti-leucine-rich repeat and immunoglobulin-like domain containing neurite outgrowth inhibitor receptor-interacting protein-1, natalizumab, ocrelizumab, intrathecal rituximab); hematopoetic stem cell therapy; statins and other possible neuroprotective agents (amiloride, riluzole, fluoxetine, oxcarbazepine); lithium; phosphodiesterase inhibitors (ibudilast); hormone-based therapies (adrenocorticotrophic hormone and erythropoietin); T-cell receptor peptide vaccine (NeuroVax); autologous T-cell immunotherapy (Tcelna); MIS416 (a microparticulate immune response modifier); dopamine antagonists (domperidone); and nutritional supplements, including lipoic acid, biotin, and sunphenon epigallocatechin-3-gallate (green tea extract). Given ongoing and planned clinical trial initiatives, and the largest ever focus of the global research community on progressive MS, future prospects for developing targeted therapeutics aimed at reducing disability in progressive forms of MS appear promising.

Developing Biomarkers for MS

Existing clinical outcomes of disease activity, including relapse rates, are inherently insensitive to the underlying pathological process in MS. Moreover, it is extremely difficult to measure clinical disability in patients, which is often a retrospective assessment, and definitely not within the time frame of a clinical trial. Biomarkers , conversely are more specific for a pathologic process and if used correctly can prove invaluable in the diagnosis, stratification and monitoring of disease activity, including any subclinical activity which is not visible to the naked eye. In this chapter, we discuss the development of neurofilaments as surrogate outcomes of disability in MS. The validation and qualification are vital steps in biomarker development and to gaining acceptance in scientific community, and the pitfalls leading up to this are also discussed.

Vitamin D and axonal injury in multiple sclerosis

Background:

Previous studies in patients with multiple sclerosis (MS) have shown an association between high serum 25-hydroxyvitamin D (25[OH]D) levels and decreased inflammatory activity.

Objective:

The purpose of this study was to examine the association between 25(OH)D levels and axonal injury in MS. Cerebrospinal fluid neurofilament light (CSF-NFL) was used as a marker for axonal injury.

Methods:

Patients were identified through clinical practice at the Department of Neurology in Umeå University Hospital, Sweden. Blood draw, magnetic resonance imaging, scoring of disability and lumbar puncture were performed at inclusion in 153 patients, and also at median 12 months follow-up in 87 patients. For analyses of serum 25(OH)D levels and CSF-NFL, enzyme-linked immunosorbent assays were used.

Results:

There was an inverse association between serum 25(OH)D and CSF-NFL levels in categorical (dichotomized at 75 or 100 nmol/l) analyses. A dose-response effect for 25(OH)D levels on CSF-NFL levels ( p for trend=0.034) was also present. Serum 25(OH)D levels above 100 nmol/l were associated with lower CSF-NFL levels independently of ongoing MS treatment.

Conclusion:

High 25(OH)D levels are associated with decreased axonal injury in MS.

Body fluid biomarkers for multiple sclerosis--the long road to clinical application

There is a strong unmet clinical need for objective body fluid biomarkers to assist early diagnosis and estimate long-term prognosis, monitor treatment response and predict potential adverse effects in multiple sclerosis (MS). Here, we review recent studies (focusing on 2012 to early 2015) on body fluid markers in MS from the perspective of their clinical utility. Because the first step towards clinical implementation of a newly discovered biomarker is independent replication, we focus on biomarkers that have been validated in at least two independent cohorts. We also discuss recent data challenging earlier findings, and biomarkers for which new clinical uses are suggested. For early MS diagnosis and prediction of conversion from clinically isolated syndrome to MS, several new B-cell-associated candidate blood biomarkers have emerged. For prognosis, several novel axonal damage markers should be adopted to biomarker panels. The number of disease-modifying treatments for MS has increased sharply, but biomarkers for treatment response monitoring and adverse effect prediction are scarce, and markers for subtyping and staging of MS are still lacking. In view of the availability and implementation of several standardized protocols to optimize biomarker studies, we expect biomarker development for MS to be improved and accelerated, with clinical implementation in the near future.

Levels and Age Dependency of Neurofilament Light and Glial Fibrillary Acidic Protein in Healthy Individuals and Their Relation to the Brain Parenchymal Fraction

Background

Neurofilament light (NFL) and Glial Fibrillary Acidic Protein (GFAP) are integral parts of the axonal and astrocytal cytoskeletons respectively and are released into the cerebrospinal fluid (CSF) in cases of cellular damage. In order to interpret the levels of these biomarkers in disease states, knowledge on normal levels in the healthy is required. Another biomarker for neurodegeneration is brain atrophy, commonly measured as brain parenchymal fraction (BPF) using magnetic resonance imaging (MRI). Potential correlations between levels of NFL, GFAP and BPF in healthy individuals have not been investigated.

Objectives

To present levels of NFL and GFAP in healthy individuals stratified for age, and investigate the correlation between them as well as their correlation with BPF.

Methods

The CSF was analysed in 53 healthy volunteers aged 21 to 70 (1 sample missing for GFAP analysis) and 48 of the volunteers underwent determination of BPF using MRI.

Results

Mean (±SD) NFL was 355 ng/L (±214), mean GFAP was 421 ng/L (±129) and mean BPF was 0.867 (±0.035). All three biomarkers correlated with age. NFL also correlated with both GFAP and BPF. When controlled for age, only the correlation between NFL and GFAP retained statistical significance.

Conclusions

This study presents data on age-stratified levels of NFL and GFAP in the CSF of healthy individuals. There is a correlation between levels of NFL and GFAP and both increase with age. A correlation between NFL and BPF was also found, but did not retain statistical significance if controlled for age.

Cerebrospinal fluid neurofilament light chain levels predict visual outcome after optic neuritis

Background:

Optic neuritis is a good model for multiple sclerosis relapse, but currently no tests can accurately predict visual outcome.

Objective:

The purpose of this study was to examine whether cerebrospinal fluid (CSF) biomarkers of tissue damage and remodelling (neurofilament light chain (NF-L), myelin basic protein, osteopontin and chitinase-3-like-1) predict visual outcome after optic neuritis.

Methods:

We included 47 patients with optic neuritis as a first demyelinating episode. Patients underwent visual tests, optical coherence tomography (OCT), magnetic resonance imaging (MRI) and lumbar puncture. Biomarkers were measured in CSF by enzyme-linked immunosorbent assay (ELISA). Patients were followed up six months after onset and this included visual tests and OCT. Outcome measures were inter-ocular differences in low contrast visual acuity (LCVA), retinal nerve fibre layer (RNFL) and ganglion cell layer+inner plexiform layer (GC-IPL) thicknesses.

Results:

CSF NF-L levels at onset predicted inter-ocular differences in follow-up LCVA (β=13.8, p=0.0008), RNFL (β=5.6, p=0.0004) and GC-IPL (β=4.0, p=0.0008). The acute-phase GC-IPL thickness also predicted follow-up LCVA (β=12.9, p=0.0021 for NF-L, β=−1.1, p=0.0150 for GC-IPL). Complete/incomplete remission was determined based on LCVA from 30 healthy controls. NF-L had a positive predictive value of 91% and an area under the curve (AUC) of 0.79 for incomplete remission.

Conclusion:

CSF NF-L is a promising biomarker of visual outcome after optic neuritis. This could aid neuroprotective/regenerative medical advancements.

Brain-Specific Cytoskeletal Damage Markers in Cerebrospinal Fluid: Is There a Common Pattern between Amyotrophic Lateral Sclerosis and Primary Progressive Multiple Sclerosis?

Many neurodegenerative disorders share a common pathophysiological pathway involving axonal degeneration despite different etiological triggers. Analysis of cytoskeletal markers such as neurofilaments, protein tau and tubulin in cerebrospinal fluid (CSF) may be a useful approach to detect the process of axonal damage and its severity during disease course. In this article, we review the published literature regarding brain-specific CSF markers for cytoskeletal damage in primary progressive multiple sclerosis and amyotrophic lateral sclerosis in order to evaluate their utility as a biomarker for disease progression in conjunction with imaging and histological markers which might also be useful in other neurodegenerative diseases associated with affection of the upper motor neurons. A long-term benefit of such an approach could be facilitating early diagnostic and prognostic tools and assessment of treatment efficacy of disease modifying drugs.

Comparative Assessment of the Prognostic Value of Biomarkers in Traumatic Brain Injury Reveals an Independent Role for Serum Levels of Neurofilament Light

Traumatic brain injury (TBI) is a common cause of death and disability, worldwide. Early determination of injury severity is essential to improve care. Neurofilament light (NF-L) has been introduced as a marker of neuroaxonal injury in neuroinflammatory/-degenerative diseases. In this study we determined the predictive power of serum (s-) and cerebrospinal fluid (CSF-) NF-L levels towards outcome, and explored their potential correlation to diffuse axonal injury (DAI). A total of 182 patients suffering from TBI admitted to the neurointensive care unit at a level 1 trauma center were included. S-NF-L levels were acquired, together with S100B and neuron-specific enolase (NSE). CSF-NF-L was measured in a subcohort (n = 84) with ventriculostomies. Clinical and neuro-radiological parameters, including computerized tomography (CT) and magnetic resonance imaging, were included in the analyses. Outcome was assessed 6 to 12 months after injury using the Glasgow Outcome Score (1-5). In univariate proportional odds analyses mean s-NF-L, -S100B and -NSE levels presented a pseudo-R2 Nagelkerke of 0.062, 0.214 and 0.074 in correlation to outcome, respectively. In a multivariate analysis, in addition to a model including core parameters (pseudo-R2 0.33 towards outcome; Age, Glasgow Coma Scale, pupil response, Stockholm CT score, abbreviated injury severity score, S100B), S-NF-L yielded an extra 0.023 pseudo-R2 and a significantly better model (p = 0.006) No correlation between DAI or CT assessed-intracranial damage and NF-L was found. Our study thus demonstrates that S-NF-L correlates to TBI outcome, even if used in models with S100B, indicating an independent contribution to the prediction, perhaps by reflecting different pathophysiological processes, not possible to monitor using conventional neuroradiology. Although we did not find a predictive value of NF-L for DAI, this cannot be completely excluded. We suggest further studies, with volume quantification of axonal injury, and a prolonged sampling time, in order to better determine the connection between NF-L and DAI.