Neurofilament markers in serum and cerebrospinal fluid of patients with amyotrophic lateral sclerosis.

This study aims to determine the serum and cerebrospinal fluid (CSF) levels of neurofilament light chain (NFL) and phosphorylated neurofilament heavy chain (pNFH) in amyotrophic lateral sclerosis (ALS) patients, and to explore their feasibility as valid biomarkers for quantifying disease progression and predicting individual prognosis. 52 patients with ALS and 30 controls with noninflammatory neurological diseases were included. NFL and pNFH levels in serum and CSF were measured by enzyme-linked immunosorbent assay. Our findings showed that serum and CSF levels of NFL and pNFH in ALS patients were significantly increased. These values were negatively correlated with disease duration (except CSF NFL with disease duration) and ALSFRS-r score, and positively correlated with disease progression rate (DPR) and upper motor neuron (UMN) score, but did not correlate with bilateral median and ulnar nerve compound muscle action potential (cMAP) amplitudes (except a weak correlation between CSF NFL and cMAP amplitudes). The optimal cut-off values with high sensitivity and specificity were obtained in ROC curve analysis to discriminate ALS from controls. Kaplan-Meier survival curves illustrated that survival was significantly shorter for patients with higher neurofilament levels at diagnosis. The Cox proportional hazards regressions confirmed that NFL and pNFH were significant predictors of survival. Overall, NFL and pNFH in serum and CSF can be used as reliable biomarkers in ALS.

Neurofilament results for the phase II neuroprotection study of phenytoin in optic neuritis.

BACKGROUND: A randomized trial of phenytoin in acute optic neuritis (ON) demonstrated a 30% reduction in retinal nerve fiber layer (RNFL) loss with phenytoin versus placebo. Here we present the corresponding serum neurofilament analyses. METHODS: Eighty-six acute ON cases were randomized to receive phenytoin (4-6 mg/kg/day) or placebo for 3 months, and followed up for 6 months. Serum was collected at baseline, 3 and 6 months for analysis of neurofilament heavy chain (NfH) and neurofilament light chain (NfL). RESULTS: Sixty-four patients had blood sampling. Of these, 58 and 56 were available at 3 months, and 55 and 54 were available at 6 months for NfH and NfL, respectively. There was no significant correlation between serum NfH and NfL at the time points tested. For NfH, the difference in mean placebo - phenytoin was -44 pg/ml at 3 months (P = 0.019) and -27 pg/ml at 6 months (P = 0.234). For NfL, the difference was 1.4 pg/ml at 3 months (P = 0.726) and -1.6 pg/ml at 6 months (P = 0.766). CONCLUSIONS: At 3 months, there was a reduction in NfH, but not NFL, in the phenytoin versus placebo group, while differences at 6 months were not statistically significant. This suggests a potential neuroprotective role for phenytoin in acute ON, with the lower NfH at 3 months, when levels secondary to degeneration of the anterior visual pathway are still elevated, but not at 6 months, when levels have normalized.

Correlations between serum and CSF pNfH levels in ALS, FTD and controls: a comparison of three analytical approaches.

Background Phosphorylated neurofilament heavy (pNfH), a neuronal cytoskeleton protein, might provide a promising blood biomarker of neuronal damage in neurodegenerative diseases (NDDs). The best analytical approaches to measure pNfH levels and whether serum levels correlate with cerebrospinal fluid (CSF) levels in NDDs remain to be determined. Methods We here compared analytical sensitivity and reliability of three novel analytical approaches (homebrew Simoa, commercial Simoa and ELISA) for quantifying pNfH in both CSF and serum in samples of amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) and control subjects. Results While all three assays showed highly correlated CSF measurements, Simoa assays also yielded high between-assay correlations for serum measurements (ϱ = 0.95). Serum levels also correlated strongly with CSF levels for Simoa-based measurements (both ϱ = 0.62). All three assays allowed distinguishing ALS from controls by increased CSF pNfH levels, and Simoa assays also by increased serum pNfH levels. pNfH levels were also increased in FTD. Conclusions pNfH concentrations in CSF and, if measured by Simoa assays, in blood might provide a sensitive and reliable biomarker of neuronal damage, with good between-assay correlations. Serum pNfH levels measured by Simoa assays closely reflect CSF levels, rendering serum pNfH an easily accessible blood biomarker of neuronal damage in NDDs.

Serum biomarkers of neuronal injury in newborns evaluated for selective head cooling: a comparative pilot study.

Background Evaluation of newborns for hypoxic ischemic encephalopathy (HIE) includes laboratory and clinical parameters, as well as amplitude integrated electroencephalogram (aEEG). Based on qualifying criteria, selective head cooling (SHC) is initiated for infants with evidence of moderate to severe HIE. However, some newborns may not qualify for hypothermia therapy based on normal aEEG. Objective To compare levels of serum glial fibrillary acidic protein (GFAP), ubiquitin c-terminal hydrolase-1 (UCHL-1) protein and phosphorylated axonal neurofilament heavy chain (pNF-H), in newborns who met initial screening criteria for HIE but did not qualify for head cooling, to the levels in healthy newborns. Study design Newborns ≥36 weeks of gestational age at risk for HIE, who were evaluated but did not qualify for SHC from July 2013 through June 2014 at NYU Langone Medical Center and Bellevue Hospital center were enrolled. A control group included healthy newborns from the newborn nursery (NBN). Serum samples were collected between 24 and 48 h of life from both groups. Results There was no significant difference in the serum levels of GFAP, UCHL-1 protein and pNF-H between the two groups of infants. Conclusion Newborns at risk for HIE who met the initial criteria for head cooling but who were excluded based on normal aEEG did not show significant elevation of biomarkers of brain injury compared to healthy newborns. These findings may help to validate using aEEG as an additional evaluation criteria in cooling.

Plasma neurofilament heavy chain is not a useful biomarker in Charcot-Marie-Tooth disease.

INTRODUCTION: The negative results in trials of vitamin C in Charcot-Marie-Tooth disease (CMT) type 1A have highlighted the lack of sensitive outcome measures. Neurofilaments are abundant neuronal cytoskeletal proteins, and their concentration in blood is likely to reflect axonal breakdown. We therefore examined plasma neurofilament heavy-chain (NfH) concentration as a potential biomarker in CMT. METHODS: Blood samples were collected from healthy controls and patients with CMT over a 2-year period. Disease severity was measured using the CMT Examination Score. An in-house enzyme-linked immunoabsorbent assay was used to measure plasma NfH levels. RESULTS: There was no significant difference in plasma NfH concentrations between CMT patients and controls (P = 0.449). There was also no significant difference in plasma NfH levels in the CMT group over 1 year (mean difference = -0.02, SEM = 4.44, P = 0.98). CONCLUSIONS: Plasma NfH levels are not altered in patients with CMT and are not a suitable biomarker of disease activity. Muscle Nerve 53: 972-975, 2016.

Neurofilaments in Sporadic and Familial Amyotrophic Lateral Sclerosis: A Systematic Review and Meta-Analysis.

BACKGROUND: Neurofilament proteins have been implicated to be altered in amyotrophic lateral sclerosis (ALS). The objectives of this study were to assess the diagnostic and prognostic utility of neurofilaments in ALS. METHODS: Studies were conducted in electronic databases (PubMed/MEDLINE, Embase, Web of Science, and Cochrane CENTRAL) from inception to 17 August 2023, and investigated neurofilament light (NfL) or phosphorylated neurofilament heavy chain (pNfH) in ALS. The study design, enrolment criteria, neurofilament concentrations, test accuracy, relationship between neurofilaments in cerebrospinal fluid (CSF) and blood, and clinical outcome were recorded. The protocol was registered with PROSPERO, CRD42022376939. RESULTS: Sixty studies with 8801 participants were included. Both NfL and pNfH measured in CSF showed high sensitivity and specificity in distinguishing ALS from disease mimics. Both NfL and pNfH measured in CSF correlated with their corresponding levels in blood (plasma or serum); however, there were stronger correlations between CSF NfL and blood NfL. NfL measured in blood exhibited high sensitivity and specificity in distinguishing ALS from controls. Both higher levels of NfL and pNfH either measured in blood or CSF were correlated with more severe symptoms as assessed by the ALS Functional Rating Scale Revised score and with a faster disease progression rate; however, only blood NfL levels were associated with shorter survival. DISCUSSION: Both NfL and pNfH measured in CSF or blood show high diagnostic utility and association with ALS functional scores and disease progression, while CSF NfL correlates strongly with blood (either plasma or serum) and is also associated with survival, supporting its use in clinical diagnostics and prognosis. Future work must be conducted in a prospective manner with standardized bio-specimen collection methods and analytical platforms, further improvement in immunoassays for quantification of pNfH in blood, and the identification of cut-offs across the ALS spectrum and controls.

Phosphorylated neurofilament heavy chain in cerebrospinal fluid and plasma as a Nusinersen treatment response marker in childhood-onset SMA individuals from Serbia.

Introduction: Biomarkers capable of reflecting disease onset and short- and long-term therapeutic effects in individuals with spinal muscular atrophy (SMA) are still an unmet need and phosphorylated neurofilament heavy chain (pNF-H) holds significant promise. Methods: We conducted a longitudinal prospective study to evaluate pNF-H levels in the cerebrospinal fluid (CSF) and plasma of 29 individuals with childhood-onset SMA treated with Nuinersen (SMA type 1: n = 6, 2: n = 17, 3: n = 6). pNF-H levels before and during treatment were compared with the levels of controls (n = 22), patients with Duchenne muscular dystrophy (n = 17), myotonic dystrophy type 1 (n = 11), untreated SMA individuals with chronic type 3 disease (n = 8), and children with presymptomatic SMA (n = 3). Results: SMA type 1 showed the highest mean CSF pNF-H levels before treatment initiation. All Nusinersen-treated individuals (types 1, 2, and 3) showed significantly elevated mean baseline CSF pNF-H compared to controls, which inversely correlated with age at disease onset, age at first dose, disease duration and the initial CHOP INTEND result (SMA type 1 and 2). During 22 months of treatment, CSF pNF-H levels declined during loading doses, stabilizing at reduced levels from the initial maintenance dose in all individuals. Baseline plasma pNF-H levels in type 1 and 2 SMA were significantly increased compared to other cohorts and decreased notably in type 1 after 2 months of treatment and type 2 after 14 months. Conversely, SMA type 3, characterized by lower baseline pNF-H levels, did not show significant fluctuations in plasma pNF-H levels after 14 months of treatment. Conclusion: Our findings suggest that CSF pNF-H levels in untreated SMA individuals are significantly higher than in controls and that monitoring of CSF pNF-H levels may serve as an indicator of rapid short-term treatment response in childhood-onset SMA individuals, irrespective of the subtype of the disease, while also suggesting its potential for assessing long-term suppression of neurodegeneration. Plasma pNF-H may serve as an appropriate outcome measure for disease progression and/or response to treatment in types 1 and 2 but not in type 3. Presymptomatic infants with SMA may show elevated pNF-H levels, confirming early neuronal degeneration.

[Possibilities of magnetic resonance morphometry and laboratory biomarkers in studying the progression of multiple sclerosis]. / Vozmozhnosti magnitno-rezonansnoi morfometrii i laboratornykh biomarkerov v izuchenii progressirovaniya rasseyannogo skleroza.

OBJECTIVE: To show that magnetic resonance morphometry and laboratory biomarkers are promising methods for early detection of progressive forms of multiple sclerosis (MS). MATERIAL AND METHODS: Eighty-one patients with MS were examined, magnetic resonance morphometry was performed in all of them, 60 patients were analyzed for neurofilament light chains (sNFL), phosphorylated neurofilament heavy chains (spNFH) and glial fibrillary protein (sGFAP) in serum by enzyme-linked immunosorbent assay. RESULTS: Brain volumes were negatively correlated with disease duration, EDSS score, 25-foot walk test score and 9-ring test and positively correlated with the Symbol-Numeric Test and the Montreal Cognitive Assessment. Patients with progressive types of MS (PMS) had smaller volumes of brain gray matter, cerebellar white matter, occipital lobes, caudate nucleus, hippocampus, pallidum, thalamus, and contiguous nucleus. A CSF volume greater than 15.06% could suggest progression (CI 54.79-91%) with a sensitivity of 77.78% and specificity of 70.18%. When patients were on DMT, they had larger thalamic volumes (median 1.09% [1.6; 1.16] vs 1.04% [0.95; 1.14]; p=0.02) and smaller CSF volumes (13.86±2.87% vs. 15.55±3.49%; p=0.03). The levels of sNFL and spNFH were not increased in PMS and during exacerbations, and the low obtained values of sNFL suggest poor sensitivity of the method. There were trends (p=0.374) towards higher sGFAP in patients with PRS (median 3.2 ng/mL [1.85; 4.6] compared to remitting MS (2.05 ng/mL [1.29; 4.52]). CONCLUSION: The results demonstrate the differences in brain volumes in patients with different types of MS and emphasize the importance of long-term follow-up to better assess disease progression.

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

BACKGROUND: There is a lack of reliable biomarkers of axonal degeneration. Neurofilaments are promising candidates to fulfil this task. We compared two highly sensitive assays to measure two subunits of the neurofilament protein (neurofilament light (NfL) and neurofilament heavy chain (NfH)). METHODS: We evaluated the analytical and clinical performance of the UmanDiagnostics NF-light(®) enzyme-linked immunosorbent assay (ELISA) in the cerebrospinal fluid (CSF) of a group of 148 patients with clinically isolated syndrome (CIS) or multiple sclerosis (MS), and 72 controls. We compared our results with referring levels of our previously-developed CSF NfH(SMI35) assay. RESULTS: Exposure to room temperature (up to 8 days) or repetitive thawing (up to 4 thaws) did not influence measurement of NfL concentrations. Values of NfL were higher in all disease stages of CIS/MS, in comparison to controls (p ≤ 0.001). NfL levels correlated with the Expanded Disability Status Scale (EDSS) score in patients with relapsing disease (r(s) = 0.31; p = 0.002), spinal cord relapses and with CSF markers of acute inflammation. The ability of NfL to distinguish patients from controls was greater than that of NfH(SMI35) in both CIS patients (p = 0.001) and all MS stages grouped together (p = 0.035). CONCLUSIONS: NfL proved to be a stable protein, an important prerequisite for a reliable biomarker, and the NF-light(®) ELISA performed better in discriminating patients from controls, compared with the ECL-NfH(SMI35) immunoassay. We confirmed and expanded upon previous findings regarding neurofilaments as quantitative markers of neurodegeneration. Our results further support the role of neurofilaments as a potential surrogate measure for neuroprotective treatment in MS studies.

Neurofilament light and heavy subunits compared as therapeutic biomarkers in multiple sclerosis.

BACKGROUND: Neurofilaments are promising biomarkers in multiple sclerosis (MS) and increased levels in cerebrospinal fluid (CSF) indicate axonal damage or degeneration. In a previous study, neurofilament light chain (NfL) levels in CSF of relapsing remitting (RR) patients with MS were normalized by natalizumab treatment. AIMS OF THE STUDY: We compared the coherence between NfL and neurofilament heavy chain (NfH(SMI) (35) ) levels in longitudinal CSF samples in a subset of these patients. METHODS: In 30 patients with RRMS, CSF was obtained prior to and following 12 months of natalizumab treatment. NfH(SMI) (35) was measured by an electrochemiluminescence-based immunoassay. NfL levels were determined previously by the UmanDiagnostics NF-light(®) assay. RESULTS: NfH(SMI) (35) decreased in 73.3% and NfL in 90% of the patients following natalizumab treatment (32.4 vs 27.4 pg/ml, P = 0.002 and 820 vs 375 pg/ml, P < 0.0001). Patients experiencing a relapse showed higher NfH(SMI) (35) levels compared with patients in remission (47.7 vs 27.6 pg/ml, n = 8, P = 0.001). This difference was less obvious for NfL (1055 vs 725 pg/ml, P = 0.256). In patients in remission, NfL levels were lower following natalizumab treatment (830 vs 365 pg/ml, n = 20, P = 0.0002), whereas the same comparison failed significance for NfH(SMI) (35) (28.3 vs 26.9 pg/ml, P = 0.086). CONCLUSIONS: We confirm previous findings, indicating reduced axonal damage under natalizumab treatment by measuring NfH(SMI) (35) , using an assay with independent methodology. In comparison with NfH(SMI) (35) , NfL changes were more pronounced and the treatment effect also included patients in remission. Our results suggest that NfL is superior over NfH(SMI) (35) as therapeutic biomarker and is a promising candidate to measure neuroaxonal damage in MS treatment trials.

Biochemical analyses of tau and other neuronal markers in the submandibular gland and frontal cortex across stages of Alzheimer disease.

Hyperphosphorylation of the microtubule-associated protein tau is hypothesized to lead to the development of neurofibrillary tangles in select brain regions during normal aging and in Alzheimer disease (AD). The distribution of neurofibrillary tangles is staged by its involvement starting in the transentorhinal regions of the brain and in final stages progress to neocortices. However, it has also been determined neurofibrillary tangles can extend into the spinal cord and select tau species are found in peripheral tissues and this may be depended on AD disease stage. To further understand the relationships of peripheral tissues to AD, we utilized biochemical methods to evaluate protein levels of total tau and phosphorylated tau (p-tau) as well as other neuronal proteins (i.e., tyrosine hydroxylase (TH), neurofilament heavy chain (NF-H), and microtubule-associated protein 2 (MAP2)) in the submandibular gland and frontal cortex of human cases across different clinicopathological stages of AD (n = 3 criteria not met or low, n = 6 intermediate, and n = 9 high likelihood that dementia is due to AD based on National Institute on Aging-Reagan criteria). We report differential protein levels based on the stage of AD, anatomic specific tau species, as well as differences in TH and NF-H. In addition, exploratory findings were made of the high molecular weight tau species big tau that is unique to peripheral tissues. Although sample sizes were small, these findings are, to our knowledge, the first comparison of these specific protein changes in these tissues.

Alteration of neurofilament heavy chain and its phosphoforms reveals early subcellular damage beyond the optic nerve head in glaucoma.

Background: Retinal ganglion cells (RGCs) axon loss at the site of optic nerve head (ONH) is long believed as the common pathology in glaucoma since different types of glaucoma possessing different characteristic of intraocular pressure, and this damage was only detected at the later stage. Methods: To address these disputes and detect early initiating events underlying RGCs, we firstly detected somatic or axonal change and compared their difference in acute and chronic phase of primary angle-closed glaucoma (PACG) patient using optical coherence tomography (OCT), then an axonal-enriched cytoskeletal protein neurofilament heavy chain and its phosphoforms (NF-H, pNF-H) were utilized to reveal spatio-temporal undetectable damage insulted by acute and chronic ocular hypertension (AOH, COH) in two well characterized glaucoma mice models. Results: In clinic, we detected nonhomogeneous changes such as ONH and soma of RGCs presenting edema in acute phase but atrophy in chronic one by OCT. In AOH animal models, an increase expression of NF-H especially its phosphorylation modification was observed as early as 4 h before RGCs loss, which presented as somatic accumulation in the peripheral retina and at the sites of ONH. In contrast, in microbeads induced COH model, NF-H and pNF-H reduced significantly, these changes firstly occurred as NF-H or pNF-H disconnection at ONH and optic nerve after 2 weeks when the intraocular pressure reaching the peak; Meanwhile, we detected aqueous humor pNF-H elevation after AOH and slight reduction in the COH. Conclusion: Together, our data supports that early alteration of NF-H and its phosphoforms would reveal undetectable subcellular damage consisting of peripheral somatic neurofilament compaction, impaired axonal transport and distal axonal disorganization of cytoskeleton beyond the ONH, and identifies two distinct axonal degeneration which were Wallerian combination with retrograde degeneration in acute PACG and retrograde degeneration in the chronic one.

Atypical miller-fisher syndrome after COVID-19 and sleeve gastrectomy: Contribution of neurochemical markers to early diagnosis.

Background: The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began in late 2019. More recently, there have been sporadic case reports on development of Miller-Fisher Syndrome , a rare variant of Guillain-Barré Syndrome in COVID-19 patients. Case report: We reported herein the case of a French young women presenting with ophtalmoplegia, cerebellar ataxia, and universal areflexia following a bariatric surgery (sleeve gastrectomy). A concomitant COVID-19 diagnosis was retained based on microbiological testing. The patient was successfully treated after high-dose intravenous thiamine, but areflexia persisted. Underlying COVID-19 related Miller-Fisher Syndrome was established on physical examination and confirmed by pathologic neurophysiological findings and elevated level of phosphorylated neurofilament heavy chain protein in cerebrospinal fluid analysis. Conclusions: Guillain-Barré Syndrome and its variants after SARS-CoV-2 infection are extremely rare. The measurement of phosphorylated neurofilament heavy chain protein should be considered as an easy tool to detect an early affection of the peripheral nervous system.

Serum neurofilament levels in patients with multiple sclerosis: A comparison of SIMOA and high sensitivity ELISA assays and contributing factors to ELISA levels.

BACKGROUND: Serum neurofilaments (sNfs), especially the most investigated serum neurofilament light chain (sNfL), are promising biomarkers in multiple sclerosis (MS). However, their clinical utility is still limited, given the availability and costs of accessible analytical methods. The gold standard for the detection of sNfs is represented by the single molecule arrays (SIMOA). Recently, a high sensitivity enzyme-linked immunosorbent assay (hsELISA) has also been introduced. The objective of the study was to compare both assays for the determination of sNfL and neurofilament heavy chain (sNfH) concentrations in a defined MS cohort. The second objective was to identify contributing factors to sNfs concentrations determined by hsELISA. METHODS: Serum samples were collected from MS patients attending the MS Centre, University Hospital Ostrava, Czech Republic. The levels of sNfs were detected using SIMOA and hsELISA assays. RESULTS: The Spearman's rank correlation coefficient between the sNfL SIMOA and sNfL hsELISA and between the sNfH SIMOA and sNfH hsELISA was moderate rs= 0.543 (p = 0.001) and rs= 0.583 (p = 0.001), respectively. The Passing-Bablok regression analysis demonstrated bias between both methods. Equally significant bias between the methods was confirmed by the Bland-Altman plots. Furthermore, confounding factors affecting the sNfL levels were glomerular filtration rate (eGFR; 95% CI -2.34 to -0.04) and sex (95% CI -2.38 to -0.10). The sNfH levels were affected by age (95% CI 0.01 to 0.07), eGFR (95% CI -2.45 to -0.02), body mass index (BMI; 95% CI -0.31 to -0.05), and blood volume (95% CI 0.69 to 3.35). CONCLUSION: This analytical study showed significant differences between hsELISA and SIMOA methods, especially for the sNfH concentrations. We identified confounding factors for sNfs levels determined by hsELISA. The sNfs levels were influenced by renal function and sex, whilst sNfH levels were affected by age, BMI, and total blood volume.

Neurofilament Levels Are Reflecting the Loss of Presynaptic Dopamine Receptors in Movement Disorders.

Aims: Neurofilament light chain (NfL) and phosphorylated neurofilament heavy chain (pNfH) are biomarkers for neuroaxonal damage. We assessed whether NfL and other biomarker levels in the CSF are correlated to the loss of presynaptic dopamine transporters in neurons as detected with dopamine transporter SPECT (DaTscan). Methods: We retrospectively identified 47 patients (17 Alzheimer's dementia, 10 idiopathic Parkinson's disease, 7 Lewy body dementia, 13 progressive supranuclear palsy or corticobasal degeneration) who received a DaTscan and a lumbar puncture. DaTscan imaging was performed according to current guidelines, and z-scores indicating the decrease in uptake were software based calculated for the nucleus caudatus and putamen. The CSF biomarkers progranulin, total-tau, alpha-synuclein, NfL, and pNfH were correlated with the z-scores. Results: DaTscan results in AD patients did not correlate with any biomarker. Subsuming every movement disorder with nigrostriatal neurodegeneration resulted in a strong correlation between putamen/nucleus caudatus and NfL (nucleus caudatus right p < 0.01, putamen right p < 0.05, left p < 0.05) and between pNfH and putamen (right p < 0.05; left p < 0.042). Subdividing in disease cohorts did not reveal significant correlations. Progranulin, alpha-synuclein, and total-tau did not correlate with DaTscan results. Conclusion: We show a strong correlation of NfL and pNfH with pathological changes in presynaptic dopamine transporter density in the putamen concomitant to nigrostriatal degeneration. This correlation might explain the reported correlation of impaired motor functions in PD and NfL as seen before, despite the pathological heterogeneity of these diseases.

Neurofilaments in progressive multiple sclerosis: a systematic review.

BACKGROUND: Neurofilament proteins have been extensively studied in relapsing-remitting multiple sclerosis, where they are promising biomarkers of disease activity and treatment response. Their role in progressive multiple sclerosis, where there is a particularly urgent need for improved biomarkers, is less clear. The objectives of this systematic review are to summarise the literature on neurofilament light and heavy in progressive multiple sclerosis, addressing key questions. METHODS: A systematic search of PubMed, Embase, Web of Science and Scopus identified 355 potential sources. 76 relevant sources were qualitatively reviewed using QUADAS-2 criteria, and 17 were identified as at low risk of bias. We summarise the findings from all relevant sources, and separately from the 17 high-quality studies. RESULTS: Differences in neurofilament light between relapsing-remitting and progressive multiple sclerosis appear to be explained by differences in covariates. Neurofilament light is consistently associated with current inflammatory activity and future brain atrophy in progressive multiple sclerosis, and is consistently shown to be a marker of treatment response with immunosuppressive disease-modifying therapies. Associations with current or future disability are inconsistent, and there is no evidence of NFL being a responsive marker of purportedly neuroprotective treatments. Evidence on neurofilament heavy is more limited and inconsistent. CONCLUSIONS: Neurofilament light has shown consistent utility as a biomarker of neuroinflammation, future brain atrophy and immunosuppressive treatment response at a group level. Neither neurofilament light or heavy has shown a consistent treatment response to neuroprotective disease-modifying therapies, which will require further data from successful randomised controlled trials.

Phosphorylated Neurofilament Heavy Chain in the Cerebrospinal Fluid Is a Suitable Biomarker of Acute and Chronic Blast-Induced Traumatic Brain Injury.

Blast-induced traumatic brain injury (bTBI) has been documented as a significant concern for both military and civilian populations in response to the increased use of improvised explosive devices. Identifying biomarkers that could aid in the proper diagnosis and assessment of both acute and chronic bTBI is in urgent need since little progress has been made towards this goal. Addressing this knowledge gap is especially important in military veterans who are receiving assessment and care often years after their last blast exposure. Neuron-specific phosphorylated neurofilament heavy chain protein (pNFH) has been successfully evaluated as a reliable biomarker of different neurological disorders, as well as brain trauma resulting from contact sports and acute stages of brain injury of different origin. In the present study, we have evaluated the utility of pNFH levels measured in the cerebrospinal fluid (CSF) as an acute and chronic biomarker of brain injury resulting from single and tightly coupled repeated blast exposures using experimental rats. The pNFH levels increased at 24 h, returned to normal levels at 1 month, but increased again at 6 months and 1 year post-blast exposures. No significant changes were observed between single and repeated blast-exposed groups. To determine whether the observed increase of pNFH in CSF corresponded with its levels in the brain, we performed fluorescence immunohistochemistry in different brain regions at the four time-points evaluated. We observed decreased pNFH levels in those brain areas at 24 h, 6 months, and 1 year. The results suggest that blast exposure causes axonal degeneration at acute and chronic stages resulting in the release of pNFH, the abundant neuronal cytoskeletal protein. Moreover, the changes in pNFH levels in the CSF negatively correlated with the neurobehavioral functions in the rats, reinforcing suggestions that CSF levels of pNFH can be a suitable biomarker of bTBI.

Current application of neurofilaments in amyotrophic lateral sclerosis and future perspectives.

Motor neuron disease includes a heterogeneous group of relentless progressive neurological disorders defined and characterized by the degeneration of motor neurons. Amyotrophic lateral sclerosis is the most common and aggressive form of motor neuron disease with no effective treatment so far. Unfortunately, diagnostic and prognostic biomarkers are lacking in clinical practice. Neurofilaments are fundamental structural components of the axons and neurofilament light chain and phosphorylated neurofilament heavy chain can be measured in both cerebrospinal fluid and serum. Neurofilament light chain and phosphorylated neurofilament heavy chain levels are elevated in amyotrophic lateral sclerosis, reflecting the extensive damage of motor neurons and axons. Hence, neurofilaments are now increasingly recognized as the most promising candidate biomarker in amyotrophic lateral sclerosis. The potential usefulness of neurofilaments regards various aspects, including diagnosis, prognosis, patient stratification in clinical trials and evaluation of treatment response. In this review paper, we review the body of literature about neurofilaments measurement in amyotrophic lateral sclerosis. We also discuss the open issues concerning the use of neurofilaments clinical practice, as no overall guideline exists to date; finally, we address the most recent evidence and future perspectives.

NfL and pNfH are increased in Friedreich's ataxia.

OBJECTIVE: To assess neurofilaments as neurodegenerative biomarkers in serum of patients with Friedreich's ataxia. METHODS: Single molecule array measurements of neurofilament light (NfL) and heavy chain (pNfH) in 99 patients with genetically confirmed Friedreich's ataxia. Correlation of NfL/pNfH serum levels with disease severity, disease duration, age, age at onset, and GAA repeat length. RESULTS: Median serum levels of NfL were 21.2 pg/ml (range 3.6-49.3) in controls and 26.1 pg/ml (0-78.1) in Friedreich's ataxia (p = 0.002). pNfH levels were 23.5 pg/ml (13.3-43.3) in controls and 92 pg/ml (3.1-303) in Friedreich's ataxia (p = 0.0004). NfL levels were significantly increased in younger patients (age 16-31 years, p < 0.001) and patients aged 32-47 years (p = 0.008), but not in patients of age 48 years and older (p = 0.41). In a longitudinal assessment, there was no difference in NfL levels in 14 patients with repeated sampling 2 years after baseline measurement. Levels of NfL correlated inversely with GAA1 repeat length (r = - 0.24, p = 0.02) but not with disease severity (r = - 0.13, p = 0.22), disease duration (r = - 0.06, p = 0.53), or age at onset (r = 0.05, p = 0.62). CONCLUSION: Serum levels of NfL and pNfH are elevated in Friedreich's ataxia, but differences to healthy controls decrease with increasing age. Long-term longitudinal data are required to explore whether this reflects a selection bias from early death of more severely affected individuals or a slowing down of the neurodegenerative process with age. In a pilot study over 2 years of follow-up-a period relevant for biomarkers indicating treatment effects-we found NfL levels to be stable.

Neurofilaments in spinocerebellar ataxia type 3: blood biomarkers at the preataxic and ataxic stage in humans and mice.

With molecular treatments coming into reach for spinocerebellar ataxia type 3 (SCA3), easily accessible, cross-species validated biomarkers for human and preclinical trials are warranted, particularly for the preataxic disease stage. We assessed serum levels of neurofilament light (NfL) and phosphorylated neurofilament heavy (pNfH) in ataxic and preataxic subjects of two independent multicentric SCA3 cohorts and in a SCA3 knock-in mouse model. Ataxic SCA3 subjects showed increased levels of both NfL and pNfH. In preataxic subjects, NfL levels increased with proximity to the individual expected onset of ataxia, with significant NfL elevations already 7.5 years before onset. Cross-sectional NfL levels correlated with both disease severity and longitudinal disease progression. Blood NfL and pNfH increases in human SCA3 were each paralleled by similar changes in SCA3 knock-in mice, here also starting already at the presymptomatic stage, closely following ataxin-3 aggregation and preceding Purkinje cell loss in the brain. Blood neurofilaments, particularly NfL, might thus provide easily accessible, cross-species validated biomarkers in both ataxic and preataxic SCA3, associated with earliest neuropathological changes, and serve as progression, proximity-to-onset and, potentially, treatment-response markers in both human and preclinical SCA3 trials.