Neurofilament light chain in demyelinating conditions of the central nervous system: a promising biomarker

Neurofilaments are the major structural proteins of the neuronal cytoskeleton and are classified according to molecular weight into heavy,intermediate,and light chains.They are released into the interstitial fluid and cerebrospinal fluid(CSF)as a consequence of axonal damage.In particular,the light chain(NfL)represents the most abundant and soluble subunit and has been demonstrated to be increased in the CSF of patients with inflammatory,degenerative,vascular,or traumatic injuries in correlation with clinical and radiological activity.Similar results have been obtained measuring serum NfL with high-sensitivity single-molecule array,which enables reliable and repeatable measurement of the low NfL concentrations in serum.In particular,CSF and serum NfL values are strongly correlated in patients with multiple sclerosis(MS)and have been demonstrated to be increased in patients with MS and clinically isolated syndromes(CIS)in accordance with clinical and radiological activity.NfL levels increase in patients with a recent relapse and seem to predict cognitive impairment,long-term outcome,and conversion of CIS to MS.The few available data on patients with other demyelinating diseases suggest that NfL levels are also increased in neuromyelitis optica spectrum disorders and related conditions in correlation with attack severity,suggesting that axonal damage may occur in these disorders.We herein report and discuss published data on the role of NfL as a possible predictor of disease activity,clinical outcome and treatment response in patients with demyelinating conditions of the central nervous system.

Storage time affects the level and diagnostic efficacy of plasma biomarkers for neurodegenerative diseases

Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results.

Blood diagnostic and prognostic biomarkers in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a devastating neurodegenerative disease for which the current treatment approaches remain severely limited.The principal pathological alterations of the disease include the selective degeneration of motor neurons in the brain,brainstem,and spinal cord,as well as abnormal protein deposition in the cytoplasm of neurons and glial cells.The biological markers under extensive scrutiny are predominantly located in the cerebrospinal fluid,blood,and even urine.Among these biomarke rs,neurofilament proteins and glial fibrillary acidic protein most accurately reflect the pathologic changes in the central nervous system,while creatinine and creatine kinase mainly indicate pathological alterations in the peripheral nerves and muscles.Neurofilament light chain levels serve as an indicator of neuronal axonal injury that remain stable throughout disease progression and are a promising diagnostic and prognostic biomarker with high specificity and sensitivity.However,there are challenges in using neurofilament light chain to diffe rentiate amyotrophic lateral sclerosis from other central nervous system diseases with axonal injury.Glial fibrillary acidic protein predominantly reflects the degree of neuronal demyelination and is linked to non-motor symptoms of amyotrophic lateral sclerosis such as cognitive impairment,oxygen saturation,and the glomerular filtration rate.TAR DNA-binding protein 43,a pathological protein associated with amyotrophic lateral sclerosis,is emerging as a promising biomarker,particularly with advancements in exosome-related research.Evidence is currently lacking for the value of creatinine and creatine kinase as diagnostic markers;however,they show potential in predicting disease prognosis.Despite the vigorous progress made in the identification of amyotrophic lateral sclerosis biomarkers in recent years,the quest for definitive diagnostic and prognostic biomarke rs remains a formidable challenge.This review summarizes the latest research achievements concerning blood biomarkers in amyotrophic lateral sclerosis that can provide a more direct basis for the differential diagnosis and prognostic assessment of the disease beyond a reliance on clinical manifestations and electromyography findings.

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.

Elevated plasma and CSF neurofilament light chain concentrations are stabilized in response to mutant huntingtin lowering in the brains of Huntington’s disease mice

Background Therapeutic approaches aimed at lowering toxic mutant huntingtin(mHTT)levels in the brain can reverse disease phenotypes in animal models of Huntington’s disease(HD)and are currently being evaluated in clinical trials.Sensitive and dynamic response biomarkers are needed to assess the efficacy of such candidate therapies.Neurofilament light chain(NfL)is a biomarker of neurodegeneration that increases in cerebrospinal fluid(CSF)and blood with progression of HD.However,it remains unknown whether NfL in biofluids could serve as a response biomarker for assessing the efficacy of disease-modifying therapies for HD.Methods Longitudinal plasma and cross-sectional CSF samples were collected from the YAC128 transgenic mouse model of HD and wild-type(WT)littermate control mice throughout the natural history of disease.Additionally,biofluids were collected from YAC128 mice following intracerebroventricular administration of an antisense oligonucleotide(ASO)targeting the mutant HTT transgene(HTT ASO),at ages both before and after the onset of disease phenotypes.NfL concentrations in plasma and CSF were quantified using ultrasensitive single-molecule array technology.Results Plasma and CSF NfL concentrations were significantly elevated in YAC128 compared to WT littermate control mice from 9 months of age.Treatment of YAC128 mice with either 15 or 50μg HTT ASO resulted in a dose-dependent,allele-selective reduction of mHTT throughout the brain at a 3-month interval,which was sustained with high-dose HTT ASO treatment for up to 6 months.Lowering of brain mHTT prior to the onset of regional brain atrophy and HD-like motor deficits in this model had minimal effect on plasma NfL at either dose,but led to a dose-dependent reduction of CSF NfL.In contrast,initiating mHTT lowering in the brain after the onset of neuropathological and behavioural phenotypes in YAC128 mice resulted in a dose-dependent stabilization of NfL increases in both plasma and CSF.Conclusions Our data provide evidence that the response of NfL in biofluids is influenced by the magnitude of mHTT lowering in the brain and the timing of intervention,suggesting that NfL may serve as a promising exploratory response biomarker for HD.

Proteomic analysis of trans-hemispheric motor cortex reorganization following contralateral C7 nerve transfer

Nerve transfer is the most common treatment for total brachial plexus avulsion injury. After nerve transfer, the movement of the injured limb may be activated by certain movements of the healthy limb at the early stage of recovery, i.e., trans-hemispheric reorganization. Pre- vious studies have focused on functional magnetic resonance imaging and changes in brain-derived neurotrophic factor and growth asso- ciated protein 43, but there have been no proteomics studies. In this study, we designed a rat model of total brachial plexus avulsion injury involving contralateral C7 nerve transfer. Isobaric tags for relative and absolute quantitation and western blot assay were then used to screen differentially expressed proteins in bilateral motor cortices. We found that most differentially expressed proteins in both cortices of upper limb were associated with nervous system development and function （including neuron differentiation and development, axonogenesis, and guidance）, microtubule and cytoskeleton organization, synapse plasticity, and transmission of nerve impulses. Two key differentially expressed proteins, neurofilament light （NFL） and Thy-1, were identified. In contralateral cortex, the NFL level was upregulated 2 weeks after transfer and downregulated at 1 and 5 months. The Thy-1 level was upregulated from 1 to 5 months. In the affected cortex, the NFL level increased gradually from 1 to 5 months. Western blot results of key differentially expressed proteins were consistent with the proteom- ic findings. These results indicate that NFL and Thy-1 play an important role in trans-hemispheric organization following total brachial plexus root avulsion and contralateral C7 nerve transfer.

Differential effect of ethanol intoxication on peripheral markers of cerebral injury in murine blunt traumatic brain injury

Background:Blood-based biomarkers have proven to be a reliable measure of the severity and outcome of traumatic brain injury(TBI)in both murine models and patients.In particular,neuronspecific enolase(NSE),neurofilament light(NFL)and S100 beta(S100B)have been investigated in the clinical setting post-injury.Ethanol intoxication(EI)remains a significant comorbidity in TBI,with 30–40%of patients having a positive blood alcohol concentration post-TBI.The effect of ethanol on blood-based biomarkers for the prognosis and diagnosis of TBI remains unclear.In this study,we investigated the effect of EI on NSE,NFL and S100B and their correlation with blood–brain barrier integrity in a murine model of TBI.Methods:We used ultra-sensitive single-molecule array technology and enzyme-linked immunosorbent assay methods to measure NFL,NSE,S100B and claudin-5 concentrations in plasma 3 hours post-TBI.Results:We showed that NFL,NSE and S100B were increased at 3 hours post-TBI.Interestingly,ethanol blood concentrations showed an inverse correlation with NSE but not with NFL or S100B.Claudin-5 levels were increased post-injury but no difference was detected compared to ethanol pretreatment.The increase in claudin-5 post-TBI was correlated with NFL but not with NSE or S100B.Conclusions:Ethanol induces an effect on biomarker release in the bloodstream that is different from TBI not influenced by alcohol.This could be the basis of investigations into humans.

Cerebrospinal fluid biomarkers for cognitive disorders. An introductory overview

The core(established)cerebrospinal fluid biomarkers of Alzheimer's disease(AD),namely amyloid-beta peptide,total tau protein and phospho-tau protein,have become a part of the diagnostic workup of patients with cognitive disorders in many specialized centers,especially for ambiguous cases.Combined,these biomarkers can identify the presence or absence of an AD biochemical process with sensitivities and specificities approaching or exceeding 90%in both dementia and pre-dementia stages of AD.Thus,they have been incorporated in various sets of research or clinical diagnostic criteria and recommendations.Results that are atypical,incompatible with AD,or inconclusive may occur,necessitating the use of other cerebrospinal fluid or imaging biomarkers.