Neurofilament-Light, a Promising Biomarker: Analytical, Metrological and Clinical Challenges

Plasma levels of glial fibrillary acidic protein and neurofilament light chain in patients with chronic migraine: a multicenter case-control study

OBJECTIVE

Plasma glial fibrillary acidic protein (pGFAP) and plasma neurofilament light chain (pNfL) levels reflect astrocyte activation and neuronal damage, respectively. Whether these phenomena play a role in migraine is unknown. This study aimed to compare pGFAP and pNfL levels in patients with chronic migraine (CM) and age-matched controls and to analyze their relation with clinical features.

METHODS

The study evaluated two independent cohorts of patients, including in total 58 CM and 69 controls. pGFAP and pNfL were quantified with single molecule array (Simoa) technology. Demographic and clinical data were collected for each subject; differences in NfL/GFAP levels between CM and controls were evaluated in analyses adjusted for the effect of age and sex; clinical characteristics associated with NfL/GFAP levels were separately evaluated in the two cohorts.

RESULTS

In both cohorts, we did not find a significant difference in pGFAP or pNFL levels between CM and matched controls. The study did not find any correlation between pGFAP or pNfL levels and any migraine characteristics (namely presence of migraine aura, attack frequency, migraine intensity, years of disease).

CONCLUSIONS

Our negative results support the assumption that migraine represents a benign condition, characterized by transient functional brain alterations and not by the accumulation over time of neuroaxonal damage and/or associated astrocyte activation detectable by neurodegeneration marker proteins.

Delirium pathophysiology in cancer: neurofilament light chain biomarker - narrative review

Background Delirium is a debilitating disorder with high prevalence near the end of life, impacting quality of life of patients and their relatives. Timely recognition of delirium can lead to prevention and/or better treatment of delirium. According to current hypotheses delirium is thought to result from aberrant inflammation and neurotransmission, with a possible role for neuronal damage. Neurofilament light chain (NfL) is a protein biomarker in body fluids that is unique to neurons, with elevated levels when neurons are damaged, making NfL a viable biomarker for early detection of delirium. This narrative review summarises current research regarding the pathophysiology of delirium and the potential of NfL as a susceptibility biomarker for delirium and places this in the context of care for patients with advanced cancer. Results Six studies were conducted exclusively on NfL in patients with delirium. Three of these studies demonstrated that high plasma NfL levels preoperatively predict delirium in older adult patients postoperatively. Two studies demonstrated that high levels of NfL in intensive care unit (ICU) patients are correlated with delirium duration and severity. One study found that incident delirium in older adult patients was associated with increased median NfL levels during hospitalisation. Conclusions Targeted studies are required to understand if NfL is a susceptibility biomarker for delirium in patients with advanced cancer. In this palliative care context, better accessible matrices, such as saliva or urine, would be helpful for repetitive testing. Improvement of biological measures for delirium can lead to improved early recognition and lay the groundwork for novel therapeutic strategies.

Neurofilament Light Chain and Multiple Sclerosis: Building a Neurofoundational Model of Biomarkers and Diagnosis

Neurofilament light chain (NfL), an abundant cytoskeletal protein in neurons, has emerged as a promising serum biomarker that indicates non-specific neuronal damage secondary to various neurologic diseases, including multiple sclerosis (MS). Emerging evidence suggests that serum NfL levels correlate with future disability, brain atrophy, predict new disease activity, and decrease in response to various disease-modifying therapies. As research continues to validate NfL's potential role in clinical practice, the need for a practical model to conceptualize and visualize its relevance to MS pathology becomes evident-not only for healthcare providers but also for patients. To address this, we propose the Neurofoundational Model (NFM), which likens a neuron to a home, with various parts of the home representing distinct regions of the central nervous system (CNS). In this model, the home (neuron) experiences scenarios such as a fire, an earthquake, and a slow flood, representing distinct MS disease states. A fire illustrates an MS relapse with good recovery, where serum NfL levels rise during the relapse and subsequently return near baseline. An earthquake represents an MS relapse with poor recovery, where NfL levels increase and remain elevated above baseline. Finally, a slow flood depicts MS in progressive stages, characterized by sustained and gradually increasing serum NfL levels without abrupt clinical changes. This approach offers a clear and relatable visualization for clinicians and patients alike, illustrating the dynamics of serum NfL levels during CNS damage caused by demyelination. By integrating this model into clinical practice, we aim to enhance understanding and communication regarding the role of NfL in MS pathology and its potential utility as a biomarker.

Differentiating Progressive Supranuclear Palsy and Corticobasal Syndrome: Insights from Cerebrospinal Fluid Biomarkers-A Narrative Review

Background and Objectives: Despite ongoing research and evolving diagnostic criteria, progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) remain notoriously difficult to differentiate, largely due to their overlapping clinical presentations and the absence of definitive biomarkers. Materials and Methods: We provide a comprehensive review of cerebrospinal fluid (CSF) biomarkers, which have proven valuable in the diagnosis of other neurodegenerative conditions, and their application to PSP and CBS. Results: The most promising results derive from a combination of biomarkers associated with Parkinson's disease, Alzheimer's disease, and neurofilament light chain. Furthermore, CSF proteomics analysis offers valuable insights into the pathogenesis of PSP and CBS and could also contribute to accurate diagnosis. Conclusions: CSF biomarkers hold significant potential for improving the differential diagnosis of PSP and CBS. A stepwise combination approach-starting with CSF α-synuclein and neurofilament light chain, followed by amyloid-β42 and total and phosphorylated tau-may provide clinicians with a practical framework for distinguishing PSP and CBS from other neurodegenerative disorders. To advance this field, future efforts should prioritize large-scale, multicenter studies employing standardized methodologies to enhance the validity and reproducibility of biomarker-based diagnostics. Importantly, considering the frequent pathological overlap between PSP and CBS, future studies would greatly benefit from pathology-confirmed cohorts to ensure diagnostic accuracy and to better delineate biomarker profiles across these challenging conditions.

Serum neurofilament light chain as a potential biomarker in restless legs syndrome: a cross-sectional study

OBJECTIVE

Neurofilament light chain (NfL) has emerged as a promising biomarker for several neurological diseases. Therefore, we investigated its serum levels and their association with disease characteristics, including duration, severity, and medication use in patients with restless legs syndrome (RLS).

METHOD

This cross-sectional prospective study included 71 RLS patients and 70 healthy controls. RLS patients were characterized based on disease duration, severity, and medication use. NfL levels were quantified using commercial enzyme-linked immunosorbent assay kits.

RESULT

No significant differences in NfL levels were observed between RLS patients and controls (p > 0.05). Furthermore, the levels were not significantly associated with disease duration or severity in RLS patients (p > 0.05).

CONCLUSION

These findings do not support the use of NfL as a biomarker for RLS. Further large-scale studies are needed to evaluate its role in RLS.

Comparative Performances of 4 Serum NfL Assays, pTau181, and GFAP in Patients With Amyotrophic Lateral Sclerosis

BACKGROUND AND OBJECTIVES

Selecting the most appropriate blood tests is crucial for the management of patients with amyotrophic lateral sclerosis (ALS). This study evaluates the diagnostic and prognostic performance of neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), and phosphorylated tau 181 (pTau181) biomarkers in ALS to establish their clinical relevance and cutoff values.

METHODS

In a cohort of patients from the ALS center in Montpellier, we conducted a head-to-head comparison of 4 different technologies and 3 distinct serum analytes: NfL was tested using the ultrasensitive Simoa and the microfluidic Ella platforms, along with 2 assays recently set up on clinical-grade platforms: Lumipulse and Elecsys. We also used Elecsys to assess serum GFAP and pTau181.

RESULTS

Our cohort included 139 patients with ALS and 70 non-ALS patients, with a mean age of 66.1 ± 11.4 years and 47.4% of women. The mean follow-up was 42 ± 26.3 months for patients with ALS and 141.6 ± 106.3 months for non-ALS patients, with a mortality rate of 85.5% vs 7.7%. There was a high correlation between all methods tested for serum NfL quantification (R2 = 0.939 to 0.963). The area under the curve (AUC) for ALS diagnosis was 0.889 (0.827-0.932) for NfL Simoa, 0.906 (0.847-0.944) for Ella, 0.912 (0.853-0.948) for Lumipulse, and 0.910 (0.851-0.946) for Elecsys. Serum pTau181 and GFAP showed poor diagnostic performance with AUCs of 0.565 (0.472-0.649) and 0.546 (0.461-0.636), respectively. Kaplan-Meier survival analysis revealed significant hazard ratios (4.4-5.4) for blood NfL. Patients with ALS had a 40%-50% chance of surviving 50 weeks below the prognostic cutoff values while survival rates dropped to near zero above. NfL and GFAP levels were associated with age and body mass index, considered confounding factors. pTau181 levels varied significantly in patients with ALS depending on the site of onset.

DISCUSSION

This study demonstrates the consistent performance of 4 immunoassays for serum NfL quantification in ALS. NfL showed high diagnostic and prognostic accuracy, making it suitable for individual assessment, unlike GFAP or pTau181. We propose diagnostic and prognostic cutoff values for serum NfL, providing a basis for wider implementation, especially with the clinically accredited Lumipulse and Elecsys platforms, which are becoming standard practice.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that serum NfL levels are useful in identifying over 80% of patients with ALS and predicting survival in patients with ALS compared with pTau181 and GFAP levels.

V-set and immunoglobulin domain containing 4 as a potential predictor of Alzheimer's disease and advanced aging

BackgroundV-set and immunoglobulin domain containing 4 (VSIG4) emerges as a significant player in the immune system pathways. It has been previously identified as a potential hub gene for Alzheimer's disease (AD) and aging, underscoring its importance in understanding these conditions.ObjectiveThis study aimed to evaluate the diagnostic potential of serum VSIG4 and identify trends in serum VSIG4 in relationship with other biomarkers and neurological tests.MethodsELISA was used to measure the serum concentration of VSIG4 in AD, compared to healthy subjects. The relationship between VSIG4 levels and the age of the subjects, as well as other AD-related serum proteins and various measures of cognition was examined.ResultsVSIG4 was significantly elevated in the serum of AD patients compared to healthy controls (p = 0.0074). Significant correlations were identified between serum VSIG4 and other notable proteins related to AD and inflammation, such as total tau, neurofilament light (NfL), YKL-40, CD14, FABP3, and TNF-α. Significant correlations were also identified between VSIG4 concentration and the results of neurological tests.ConclusionsSerum VSIG4 may reflect neuroinflammation and altered lipid processing, affecting the cognitive performance of AD and aging.

Metabolic and proteomic profiles provide insights on mechanism of late onset Pompe disease

Late onset Pompe disease (LOPD) is caused by a deficiency of the enzyme acid α-glucosidase, resulting in glycogen accumulation in lysosomes. The mechanism of LOPD has been less explored. In this study, we used an integrative analysis of the proteomics and metabolomics of LOPD muscle samples to reveal the potential mechanisms. Proteomic analysis identified 635 upregulated proteins and 89 downregulated proteins in the LOPD group. Similarly, metabolomic analysis revealed 15 upregulated and 143 downregulated metabolites; notably, L-arginine levels were significantly decreased in the LOPD group. Lysosome-related GO terms were significantly upregulated, while GO terms related to neurofilament, cytoskeleton, axon ensheathment, and myelin sheath were significantly downregulated. KEGG pathway analysis demonstrated that the lysosome, autophagy, and mTOR pathways were distinctly upregulated. Correlation analysis indicated that CALML3 showed a potential correlation with LOPD severity. Our study highlighted the potential crosstalk among these LOPD-related pathways. Supplementation with L-arginine could represent a promising therapeutic approach for LOPD, and CALML3 could serve as a potential biomarker for LOPD severity. These findings provide valuable insights into the pathogenesis of LOPD and suggest avenues for future therapeutic development.

The role of Neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) in MS and AQP4-NMOSD: Advancing clinical applications

Fluid biomarkers such as Glial Fibrillary Acidic Protein (GFAP) and Neurofilament Light (NfL) play important roles in the diagnosis, monitoring, and evaluation of therapeutic responses in conditions such as Multiple Sclerosis (MS) and Aquaporin-4 Neuromyelitis Optica Spectrum Disorder (AQP4-NMOSD). These biomarkers offer key insights into the underlying pathophysiological mechanisms of these diseases, enabling effective follow-up and personalized treatment approaches, which are essential for improving patient outcomes. Herein, we synthesize the structural attributes, functional roles, and clinical significance of GFAP and NfL in the context of MS and AQP4-NMOSD. We explore the critical implications of these biomarkers in disease manifestation and progression, emphasizing the necessity to develop standardized methodologies and multicentric studies to confirm their clinical applicability.

Characterizing plasma and cerebrospinal fluid biomarkers relevant to neurodegeneration in captive olive baboons (Papio anubis)

Alzheimer's disease and related dementias (ADRD) present a significant global disease burden that is only expected to grow in the future. As such, there is a need to develop and investigate biomarkers that identify individuals at risk of developing ADRD with the goal of providing early interventions and treatments. Non-human primate (NHP) models of neurodegeneration present opportunities to examine such biomarkers in a preclinical model with the ability to control several confounding factors present in research with humans. Baboons naturally develop several ADRD-related neuropathologies that humans also exhibit, including age-related tau and amyloid deposition. However, to our knowledge, there are no data characterizing fluid biomarkers relevant to neurodegeneration or ADRD in baboons. We collected plasma (N = 139) and cerebrospinal fluid (CSF, N = 44) from captive baboons ranging in age from 3-19 years old. We characterized biomarkers as a function of age, sex, and rearing status in baboons using a bead-based bioplex human assay (Thermo Fisher Scientific's Neuroscience 18-Plex Human ProcartaPlex™ Panel). Fluid biomarkers were more detectable in CSF compared to plasma. Additionally, while sex and rearing did not significantly predict biomarkers in baboons, age significantly predicted levels of eight of the 12 biomarkers detected in the assay. Linear regressions showed that CSF levels of total tau, pTau181, NGF-beta, GFAP, NF-H, and S100B were higher in older baboons, as were plasma levels of NGF-beta. Lastly, older baboons showed a higher incidence of co-occurrence of multiple biomarkers as measured in CSF, but not in plasma. These data show that baboons exhibit age-dependent changes in biomarkers used in humans for clinical screening, diagnosis, and prognosis of ADRD, thereby further demonstrating the value of baboons as a model of aging and, possibly, ADRD.

Plasma Biomarkers for Cerebral Amyloid Angiopathy and Implications for Amyloid-Related Imaging Abnormalities: A Comprehensive Review

Anti-amyloid therapies (AATs) are increasingly being recognized as promising treatment options for Alzheimer's disease (AD). Amyloid-related imaging abnormalities (ARIAs), small areas of edema and microbleeds in the brain presenting as abnormal signals in MRIs of the brain for patients with AD, are the most common side effects of AATs. While most ARIAs are asymptomatic, they can be associated with symptoms like nausea, headache, confusion, and gait instability and, less commonly, with more serious complications such as seizures and death. Cerebral amyloid angiopathy (CAA) has been found to be a major risk for ARIA development. The identification of sensitive and reliable non-invasive biomarkers for CAA has been an area of AD research over the years, but with the approval of AATs, this area has taken on a new urgency. This comprehensive review highlights several potential biomarkers, such as Aβ40, Aβ40/42, phosphorylated-tau217, neurofilament light chain, glial fibrillary acidic protein, secreted phosphoprotein 1, placental growth factor, triggering receptor expressed on myeloid cells 2, cluster of differentiation 163, proteomics, and microRNA. Identifying and staging CAA even before its consequences can be detected via neuroimaging are critical to allow clinicians to judiciously select appropriate candidates for AATs, stratify monitoring, properly manage therapeutic regimens for those experiencing symptomatic ARIAs, and optimize the treatment to achieve the best outcomes. Future studies can test potential plasma biomarkers in human beings and evaluate predictive values of individual markers for CAA severity.

Establishing Decisional Cutoff Values of Neurofilament Light Chains in Cerebrospinal Fluid Measured by Fully Automated Chemiluminescent Enzyme Immunoassay

INTRODUCTION

Neurofilament light chain (NfL) is one of the most important biomarkers in the field of clinical neurochemistry. Several analytical methods have been developed in the last decade. Recently, Fujirebio introduced a ready-to-use assay kit for measuring NfL levels in the cerebrospinal fluid (CSF) on the fully automated LUMIPULSE G System. In this study, we established the decisional cutoffs for CSF NfL.

MATERIALS AND METHODS

We performed a retrospective observational study including patients with cognitive decline. CSF NfL levels were measured by two analytical methods: the NF-light ELISA kit (UmanDiagnostics) and the Lumipulse G1200 fully automated system (Fujirebio). We calculated the cutoffs for the Lumipulse, starting from the consolidated cutoffs of the ELISA method for each age and using the equation obtained by the regression analysis.

RESULTS

The study population consisted of 100 patients with cognitive decline. The median levels of CSF NfL measured by Lumipulse and ELISA were 776.5 ± 772.6 pg/mL and 473.5 ± 443.5 pg/mL, respectively, significantly different (p < 0.001). The Spearman's rank correlation coefficient was 0.962, indicating a robust positive correlation between the two measurement methods. The equation derived from the Passing-Bablok regression analysis was CSF CLEIA = -61.16 + 1.83 × CSF ELISA. Based on this equation, we defined the decisional cutoff values.

CONCLUSIONS

Decisional cutoffs are fundamental tools for guiding clinicians to use biomarkers' results and interpretation appropriately. This is the first study establishing the decisional cutoff value of NfL measured by Lumipulse, a fully automated platform widely used in clinical laboratories.

Neurofilament Light Chain under the Lens of Structural Mass Spectrometry

Neurofilament light chain (NfL) is an early nonspecific biomarker in neurodegenerative diseases and traumatic brain injury, indicating axonal damage. This work describes the detailed structural characterization of a selected primary calibrator with the potential to be used in future reference measurement procedure (RMP) development for the accurate quantification of NfL. As a part of the described workflow, the sequence, higher-order structure as well as solvent accessibility, and hydrogen-bonding profile were assessed under three different conditions in KPBS, artificial cerebrospinal fluid, and artificial cerebrospinal fluid in the presence of human serum albumin. The results revealed that NfL is a structurally heterogeneous protein, eliciting a large conformational flexibility. Its structural ensemble changed when it was diluted with an aqueous buffer versus a surrogate matrix, artificial cerebrospinal fluid (aCSF), and/or aCSF with human serum albumin. Various regions of protection and deprotection in the protein head, central helical, and tail domains that experienced altered solvent accessibility and conformational changes caused by different solvent conditions were identified. Moreover, interfacial residues, which may play a role in a potential direct interaction between NfL and human serum albumin, emerged from hydrogen-deuterium exchange mass spectrometry (HDX-MS). These data pinpointed distinct regions of the protein that may participate in such an interaction. Overall, critical quality attributes of a potential primary calibrator for NfL measurements are provided. These findings will ultimately inform ongoing biochemical and clinical assay development procedures and manufacturing practices, giving careful consideration during sample handling and method development.

Effects of the therapeutic correction of U1 snRNP complex on Alzheimer's disease

The U1 snRNP complex recognizes pre-mRNA splicing sites in the early stages of spliceosome assembly and suppresses premature cleavage and polyadenylation. Its dysfunction may precede Alzheimer's disease (AD) hallmarks. Here we evaluated the effects of a synthetic single-stranded cDNA (APT20TTMG) that interacts with U1 snRNP, in iPSC-derived neurons from a donor diagnosed with AD and in the SAMP8 mouse model. APT20TTMG effectively binds to U1 snRNP, specifically decreasing TAU in AD neurons, without changing mitochondrial activity or glutamate. Treatment enhanced neuronal electrical activity, promoted an enrichment of differentially expressed genes related to key processes affected by AD. In SAMP8 mice, APT20TTMG reduced insoluble pTAU in the hippocampus, amyloid-beta and GFAP in the cortex, and U1-70 K in both brain regions, without cognitive changes. This study highlights the correction of the U1 snRNP complex as a new target for AD.

Neurofilament light chain: a biomarker at the crossroads of clarity and confusion for gene-directed therapies

Neurofilament light chain (NfL) is a promising biomarker for neurodegenerative diseases, measurable in both CSF and blood upon neuroaxonal damage. While CSF analysis was traditionally used, blood-based assays now offer a less invasive alternative. NfL levels correlate with disease severity and progression in conditions like Alzheimer's disease, amyotrophic lateral sclerosis, multiple sclerosis and Huntington's disease. Clinical trials demonstrate its utility as a pharmacodynamic biomarker in MS and ALS. The FDA's approval of Tofersen for SOD1-ALS based on NfL reduction underscores its growing acceptance as surrogate marker. However, challenges remain in standardizing assays, interpreting clinical correlations, low specificity and understanding the dynamics between CSF and blood NfL levels. Addressing these issues is crucial for maximizing NfL's potential in neurodegenerative disease management.

Glial fibrillary acidic protein in Alzheimer's disease: a narrative review

Astrocytes are fundamental in neural functioning and homeostasis in the central nervous system. These cells respond to injuries and pathological conditions through astrogliosis, a reactive process associated with neurodegenerative diseases such as Alzheimer's disease. This process is thought to begin in the early stages of these conditions. Glial fibrillary acidic protein (GFAP), a type III intermediate filament protein predominantly expressed in astrocytes, has emerged as a key biomarker for monitoring this response. During astrogliosis, GFAP is released into biofluids, making it a candidate for non-invasive diagnosis and tracking of neurodegenerative diseases. Growing evidence positions GFAP as a biomarker for Alzheimer's disease with specificity and disease-correlation characteristics comparable to established clinical markers, such as Aβ peptides and phosphorylated tau protein. To improve diagnostic accuracy, particularly in the presence of confounders and comorbidities, incorporating a panel of biomarkers may be advantageous. This review will explore the potential of GFAP within such a panel, examining its role in early diagnosis, disease progression monitoring and its integration into clinical practice for Alzheimer's disease management.

Comparison of a Fully Automated Platform and an Established ELISA for the Quantification of Neurofilament Light Chain in Patients With Cognitive Decline

BACKGROUND

Enzyme-linked immunosorbent assay (ELISA) is the most-used method for neurofilament light chain (NfL) quantification in cerebrospinal fluid (CSF). Recently, fully automated immunoassays for NfL measurement in CSF and blood have allowed high reproducibility among laboratories, making NfLs suitable for routine use in clinical practice. In this study, we compared the Uman Diagnostics NF-light ELISA with the fully automated platform Lumipulse.

METHODS

We enrolled 60 patients with cognitive decline, including Alzheimer disease (AD). CSF NfL levels were measured by a NF-light ELISA kit (UmanDiagnostics), and chemiluminescent enzyme immunoassay (CLEIA) on the Lumipulse G1200 platform (Fujirebio Diagnostics). Serum NfLs levels were measured by CLEIA on the Lumipulse G1200.

RESULTS

We found a significant, very strong correlation [Spearman rho = 0.94 (0.90-0.96)] between CLEIA and ELISA in CSF, and a significant moderate correlation between CSF and serum with both analytical methods [CLEIA vs serum CLEIA 0.41 (0.16-0.61); ELISA vs serum CLEIA 0.40 (0.15-0.60)]. It is worth noting that CSF CLEIA measurements were approximately 136.12 times higher than the serum measurements.

CONCLUSIONS

Our findings show a robust correlation between ELISA Uman Diagnostic and the standardized Lumipulse G1200 platform for CSF NfL measurements.

Plasma and CSF neurofilament light chain distinguish neurodegenerative from primary psychiatric conditions in a clinical setting

INTRODUCTION

People with neurodegenerative disorders (ND) frequently face diagnostic delay and misdiagnosis. We investigated blood and cerebrospinal fluid (CSF) neurofilament light chain (NfL) to distinguish ND from primary psychiatric disorders (PPD), a common challenge in clinical settings.

METHODS

Plasma and CSF NfL levels were measured and compared between groups, adjusting for age, sex, and weight.

RESULTS

A total of 337 participants were included: 136 ND, 77 PPD, and 124 Controls. Plasma NfL was 2.5-fold elevated in ND compared to PPD and had strong diagnostic performance (area under the curve, [AUC]: 0.86, 81%/85% specificity/sensitivity) that was comparable to CSF NfL (2-fold elevated, AUC: 0.89, 95%/71% specificity/sensitivity). Diagnostic performance was especially strong in younger people (40- < 60 years). Additional findings were cutoffs optimized for sensitivity and specificity, and issues important for future clinical translation.

CONCLUSIONS

This study adds important evidence for a simple blood-based biomarker to assist as a screening test for neurodegeneration and distinction from PPD, in clinical settings.

HIGHLIGHTS

NfL levels were significantly higher in ND versus PPD. Plasma NfL showed strong diagnostic performance, comparable to CSF NfL, to distinguish ND from PPD. Diagnostic performance was higher in younger people, where diagnostic challenges are greater. Further research is needed on analytical and reference range factors, for clinical translation. These findings support a simple screening blood test for neurodegeneration.

Circulating Brain Injury Biomarkers for Predicting Outcomes Following Elective Neurosurgery: A Scoping Review

OBJECTIVE

There is a need for refined methods to detect and quantify brain injuries that may be undetectable by magnetic resonance imaging and neurologic examination. This review evaluates the potential efficacy of circulating brain injury biomarkers for predicting outcomes following elective neurosurgical procedures.

METHODS

A comprehensive search was conducted using the Cochrane, PubMed, and Scopus databases.

RESULTS

Analysis of 23 relevant studies revealed that specific biomarkers, including glial fibrillary acidic protein, neurofilament light chain, neuron-specific enolase, S100B, and tau, are significantly associated with the extent of brain injury and could potentially predict postsurgical outcomes. The evaluated studies described intracranial tumor surgeries and miscellaneous neurosurgical interventions and demonstrated the complex relationship between biomarker levels and patient outcomes.

CONCLUSIONS

Circulating brain injury biomarkers show promise for providing objective insights into the extent of perioperative brain injury and improving prognostication of postsurgical outcomes. However, the heterogeneity in study designs and outcomes along with the lack of standardized biomarker thresholds underscore the need for further research.

Cerebrospinal Fluid Neurofilaments Light-Chain Differentiate Patients Affected by Alzheimer's Disease with Different Rate of Progression (RoP): A Preliminary Study

Alzheimer's disease (AD) is the most common neurodegenerative disorder and a leading cause of dementia. One major challenge for clinicians is accurately assessing the rate of disease progression (RoP) early in the diagnostic process, which is crucial for patient management and clinical trial stratification. This study evaluated the role of cerebrospinal fluid biomarkers-Aβ42, t-Tau, pTau, Neurogranin (Ng), and Neurofilament light-chain (NF-L)-in predicting RoP at the time of AD diagnosis. We included 56 AD patients and monitored cognitive impairment using MMSE scores at diagnosis and during six-month follow-up visits. RoP scores were calculated based on these assessments. Our correlation analyses revealed significant associations between RoP and pTau, Aβ42/Ng ratio, and NF-L levels. When patients were stratified by median RoP values into low-to-moderate (L-M: <2) and upper-moderate (U-M: >2) groups, those in the U-M group had notably higher CSF NF-L levels compared to the L-M group. Logistic regression analysis further demonstrated that elevated CSF NF-L levels were predictive of a faster RoP. These findings highlight the potential of CSF NF-L as a prognostic biomarker for rapid disease progression in AD. By identifying patients at risk for accelerated cognitive decline, CSF NF-L could significantly enhance early intervention strategies and improve patient management in clinical settings.

Plasma neurofilament light chain levels in chemotherapy-induced peripheral neurotoxicity according to type of anticancer drug

BACKGROUND AND PURPOSE

A real-time biomarker in chemotherapy-induced peripheral neurotoxicity (CIPN) would be useful for clinical decision-making during treatment. Neurofilament light chain (NfL) can be detected in blood in the case of neuroaxonal damage. The aim of the study was to compare the levels of plasma NfL (pNfL) according to the type of chemotherapeutic agent and the severity of CIPN.

METHODS

This single-center prospective observational longitudinal study included patients treated with paclitaxel (TX; n = 34), brentuximab vedotin (BV; n = 29), or oxaliplatin (PT; n = 19). All patients were assessed using the Total Neuropathy Score-clinical version and Common Terminology Criteria for Adverse Events before, during, and up to 6-12 months after the end of treatment. Nerve conduction studies (NCS) were performed before and after chemotherapy discontinuation. Consecutive plasma samples were analyzed for NfL levels using a Simoa® analyzer. Changes in pNfL were compared between groups and were eventually correlated with clinical and NCS data. Clinically relevant (CR) CIPN was considered to be grade ≥ 2.

RESULTS

Eighty-two patients, mostly women (59.8%), were included. One third of the patients who received TX (29.4%), BV (31%), or PT (36.8%) developed CR-CIPN, respectively, without differences among them (p = 0.854). Although pNfL significantly increased during treatment and decreased throughout the recovery period in all three groups, patients receiving TX showed significantly greater and earlier changes in pNfL levels compared to the other agents (p < 0.001).

CONCLUSIONS

A variable change in pNfL is observed depending on the type of agent and mechanism of neurotoxicity with comparable CIPN severity, strongly implying the need to identify different cutoff values for each agent.

Plasma Biomarkers of Brain Injury and Their Association With Brain MRI and Cognition in Type 1 Diabetes

OBJECTIVE

To evaluate associations between plasma biomarkers of brain injury and MRI and cognitive measures in participants with type 1 diabetes (T1D) from the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study.

RESEARCH DESIGN AND METHODS

Plasma amyloid-β-40, amyloid-β-42, neurofilament light chain (NfL), phosphorylated Tau-181 (pTau-181), and glial fibrillary acidic protein (GFAP) were measured in 373 adults who participated in the DCCT/EDIC study. MRI assessments included total brain and white matter hyperintensity volumes, white matter mean fractional anisotropy, and indices of Alzheimer disease (AD)-like atrophy and predicted brain age. Cognitive measures included memory and psychomotor and mental efficiency tests and assessments of cognitive impairment.

RESULTS

Participants were 60 (range 44-74) years old with 38 (30-51) years' T1D duration. Higher NfL was associated with an increase in predicted brain age (0.51 years per 20% increase in NfL; P < 0.001) and a 19.5% increase in the odds of impaired cognition (P < 0.01). Higher NfL and pTau-181 were associated with lower psychomotor and mental efficiency (P < 0.001) but not poorer memory. Amyloid-β measures were not associated with study measures. A 1% increase in mean HbA1c was associated with a 14.6% higher NfL and 12.8% higher pTau-181 (P < 0.0001).

CONCLUSIONS

In this aging T1D cohort, biomarkers of brain injury did not demonstrate an AD-like profile. NfL emerged as a biomarker of interest in T1D because of its association with higher HbA1c, accelerated brain aging on MRI, and cognitive dysfunction. Our study suggests that early neurodegeneration in adults with T1D is likely due to non-AD/nonamyloid mechanisms.

Exploring the effect of APOE ε4 on biomarkers of neurodegeneration in Alzheimer's disease

BACKGROUND AND AIMS

This study aims to assess the association between APOE genotype and biomarkers of neurodegeneration in Alzheimer's disease (AD).

METHODS

We performed a retrospective observational study at the University Hospital "P. Giaccone" in Palermo, Italy. We enrolled patients with cognitive decline, including AD. For each patient, we measured amyloid beta (Aβ)42, Aβ40, tau protein phosphorylated at threonine 181 (pTau), total tau (tTau), neurogranin, alpha-synuclein, and neurofilament light chain (NfL) in cerebrospinal fluid (CSF).

RESULTS

The study population consisted of 194 patients (123 AD and 71 non-AD). AD patients have significantly lower Aβ42 levels and Aβ42/40 ratio and higher pTau, tTau, and NfLs levels than non-AD patients. In AD patients, the APOEε4 allele is associated with a significantly lower Aβ42/40 ratio and higher levels of pTau, tTau, neurogranin, and alpha-synuclein. This association is not observed in non-AD patients.

CONCLUSIONS

This study provides evidence of the significant impact of the APOE ε4 allele on neurodegenerative biomarkers in AD patients, highlighting its role in exacerbating amyloid and tau pathology as well as synaptic degeneration.

Microglia Involvement into Acute and Chronic Brain Damage in Diabetic Rats: Impact of GLP-1RA and SGLT-2i

BACKGROUND

Acute and chronic brain damage in type 2 diabetes mellitus (DM) determines the need to investigate the neuroprotective potential of glucose-lowering drugs. The purpose was to directly compare the neuroprotective effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) with different duration of action and sodium-glucose cotransporter-2 inhibitors (SGLT-2i) in type 2 diabetic rats with and without stroke.

METHODS

DM was modelled using high-fat diet and nicotinamide+streptozotocin protocol. The following groups (n = 15 each) were formed: DM without treatment, treatment with liraglutide, dulaglutide, canagliflozin as well as control group without DM and treatment. After 8 weeks, 10 rats from each group underwent middle cerebral artery occlusion. In the reperfusion period neurological deficit, neuroglial damage markers and brain necrosis were evaluated. Brain slices from the remaining 5 animals in each group were histologically examined for microglial activation and neuronal damage.

RESULTS

Brain damage was similar in "DM" and "Control" (17.53 [14.23; 26.58] and 15.87 [13.40; 22.68] % of total brain volume, respectively). All study drugs diminished damage volume comparing with "DM" and "Control" whereas the necrosis volume in "DM+Liraglutide" was smaller than in "DM+Canagliflozin" and did not significantly differ from "DM+Dulaglutide" (2.9 [1.83; 4.71], 6.17 [3.88; 8.88] and 4.57 [3.27; 7.90] %). The neurological deficit was more prominent in "DM" than in "Control", while all the drugs demonstrated similar positive effect. Neurofilament light chains (NLC) did not differ between "DM" and "Control". Dulaglutide and canagliflozin caused a marked decrease in NLC. Protein S100BB level was similar in "DM" and "Control". Liraglutide caused the largest S100BB decrease, while canagliflozin did not influence it. In chronic brain ischaemia, all drugs increased the number of normal neurons, but GLP-1RAs had a more pronounced effect. DM was accompanied by increased number of activated microglial cells in Cornu Ammonis (CA)1 hippocampal region. Both GLP-1RAs reduced the number of Iba-1-positive cells, with dulaglutide being more effective than liraglutide, whereas canagliflozin did not affect this parameter.

CONCLUSIONS

GLP-1RAs and SGLT-2i have neuroprotective properties against acute and chronic brain damage in diabetic rats, although the infarct-limiting effect of GLP-1RAs may be more pronounced. GLP-1RAs and SGLT-2i exert their protective effects by directly influencing neuronal survival, whereas GLP-1RAs also affect microglia.

Functional connectivity changes in neurodegenerative biomarker-positive athletes with repeated concussions

Multimodal biomarkers may identify former contact sports athletes with repeated concussions and at risk for dementia. Our study aims to investigate whether biomarker evidence of neurodegeneration in former professional athletes with repetitive concussions (ExPro) is associated with worse cognition and mood/behavior, brain atrophy, and altered functional connectivity. Forty-one contact sports athletes with repeated concussions were divided into neurodegenerative biomarker-positive (n = 16) and biomarker-negative (n = 25) groups based on positivity of serum neurofilament light-chain. Six healthy controls (negative for biomarkers) with no history of concussions were also analyzed. We calculated cognitive and mood/behavior composite scores from neuropsychological assessments. Gray matter volume maps and functional connectivity of the default mode, salience, and frontoparietal networks were compared between groups using ANCOVAs, controlling for age, and total intracranial volume. The association between the connectivity networks and sports characteristics was analyzed by multiple regression analysis in all ExPro. Participants presented normal-range mean performance in executive function, memory, and mood/behavior tests. The ExPro groups did not differ in professional years played, age at first participation in contact sports, and number of concussions. There were no differences in gray matter volume between groups. The neurodegenerative biomarker-positive group had lower connectivity in the default mode network (DMN) compared to the healthy controls and the neurodegenerative biomarker-negative group. DMN disconnection was associated with increased number of concussions in all ExPro. Biomarkers of neurodegeneration may be useful to detect athletes that are still cognitively normal, but with functional connectivity alterations after concussions and at risk of dementia.

Longitudinal analysis of serum neurofilament light chain levels as marker for neuronal damage in hereditary transthyretin amyloidosis

OBJECTIVE

To evaluate serum neurofilament light chain (sNfL) as biomarker of disease onset, progression and treatment effect in hereditary transthyretin (ATTRv) amyloidosis patients and TTR variant (TTRv) carriers.

METHODS

sNfL levels were assessed longitudinally in persistently asymptomatic TTRv carriers (N = 12), persistently asymptomatic ATTRv amyloidosis patients (defined as asymptomatic patients but with amyloid detectable in subcutaneous abdominal fat tissue) (N = 8), in TTRv carriers who developed polyneuropathy (N = 7) and in ATTRv amyloidosis patients with polyneuropathy on treatment (TTR-stabiliser (N = 20) or TTR-silencer (N = 18)). Polyneuropathy was confirmed by nerve conduction studies or quantitative sensory testing. sNfL was analysed using a single-molecule array assay.

RESULTS

sNfL increased over 2 years in persistently asymptomatic ATTRv amyloidosis patients, but did not change in persistently asymptomatic TTRv carriers. In all TTRv carriers who developed polyneuropathy, sNfL increased from 8.4 to 49.8 pg/mL before the onset of symptoms and before polyneuropathy could be confirmed neurophysiologically. In symptomatic ATTRv amyloidosis patients on a TTR-stabiliser, sNfL remained stable over 2 years. In patients on a TTR-silencer, sNfL decreased after 1 year of treatment.

CONCLUSION

sNfL is a biomarker of early neuronal damage in ATTRv amyloidosis already before the onset of polyneuropathy. Current data support the use of sNfL in screening asymptomatic TTRv carriers and in monitoring of disease progression and treatment effect.

Combination of pathological, biochemical and behavioral evaluations for peripheral neurotoxicity assessment in isoniazid-treated rats

In drug development, assessment of non-clinical peripheral neurotoxicity is important to ensure human safety. Clarifying the pathological features and mechanisms of toxicity enables the management of safety risks in humans by estimating the degree of risk and proposing monitoring strategies. Published guidelines for peripheral neurotoxicity assessment do not provide detailed information on which endpoints should be monitored preferentially and how the results should be integrated and discussed. To identify an optimal assessment method for the characterization of peripheral neurotoxicity, we conducted pathological, biochemical (biomaterials contributing to mechanistic considerations and biomarkers), and behavioral evaluations of isoniazid-treated rats. We found a discrepancy between the days on which marked pathological changes were noted and those on which biochemical and behavioral changes were noted, suggesting the importance of combining these evaluations. Although pathological evaluation is essential for pathological characterization, the results of biochemical and behavioral assessments at the same time points as the pathological evaluation are also important for discussion. In this study, since the measurement of serum neurofilament light chain could detect changes earlier than pathological examination, it could be useful as a biomarker for peripheral neurotoxicity. Moreover, examination of semi-thin specimens and choline acetyltransferase immunostaining were useful for characterizing morphological neurotoxicity, and image analysis of semi-thin specimens enabled us to objectively show the pathological features.

Neurofilament Light Chains in Systemic Amyloidosis: A Systematic Review

Peripheral and autonomic neuropathy are common disease manifestations in systemic amyloidosis. The neurofilament light chain (NfL), a neuron-specific biomarker, is released into the blood and cerebrospinal fluid after neuronal damage. There is a need for an early and sensitive blood biomarker for polyneuropathy, and this systematic review provides an overview on the value of NfL in the early detection of neuropathy, central nervous system involvement, the monitoring of neuropathy progression, and treatment effects in systemic amyloidosis. A literature search in PubMed, Embase, and Web of Science was performed on 14 February 2024 for studies investigating NfL levels in patients with systemic amyloidosis and transthyretin gene-variant (TTRv) carriers. Only studies containing original data were included. Included were thirteen full-text articles and five abstracts describing 1604 participants: 298 controls and 1306 TTRv carriers or patients with or without polyneuropathy. Patients with polyneuropathy demonstrated higher NfL levels compared to healthy controls and asymptomatic carriers. Disease onset was marked by rising NfL levels. Following the initiation of transthyretin gene-silencer treatment, NfL levels decreased and remained stable over an extended period. NfL is not an outcome biomarker, but an early and sensitive disease-process biomarker for neuropathy in systemic amyloidosis. Therefore, NfL has the potential to be used for the early detection of neuropathy, monitoring treatment effects, and monitoring disease progression in patients with systemic amyloidosis.

Recent Research Trends in Neuroinflammatory and Neurodegenerative Disorders

Neuroinflammatory and neurodegenerative disorders including Alzheimer's disease (AD), Parkinson's disease (PD), traumatic brain injury (TBI) and Amyotrophic lateral sclerosis (ALS) are chronic major health disorders. The exact mechanism of the neuroimmune dysfunctions of these disease pathogeneses is currently not clearly understood. These disorders show dysregulated neuroimmune and inflammatory responses, including activation of neurons, glial cells, and neurovascular unit damage associated with excessive release of proinflammatory cytokines, chemokines, neurotoxic mediators, and infiltration of peripheral immune cells into the brain, as well as entry of inflammatory mediators through damaged neurovascular endothelial cells, blood-brain barrier and tight junction proteins. Activation of glial cells and immune cells leads to the release of many inflammatory and neurotoxic molecules that cause neuroinflammation and neurodegeneration. Gulf War Illness (GWI) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are chronic disorders that are also associated with neuroimmune dysfunctions. Currently, there are no effective disease-modifying therapeutic options available for these diseases. Human induced pluripotent stem cell (iPSC)-derived neurons, astrocytes, microglia, endothelial cells and pericytes are currently used for many disease models for drug discovery. This review highlights certain recent trends in neuroinflammatory responses and iPSC-derived brain cell applications in neuroinflammatory disorders.

Performance of biomarkers NF-L, NSE, Tau and GFAP in blood and cerebrospinal fluid in rat for the detection of nervous system injury

Background

Target organ toxicity is often a reason for attritions in nonclinical and clinical drug development. Leveraging emerging safety biomarkers in nonclinical studies provides an opportunity to monitor such toxicities early and efficiently, potentially translating to early clinical trials. As a part of the European Union's Innovative Medicines Initiative (IMI), two projects have focused on evaluating safety biomarkers of nervous system (NS) toxicity: Translational Safety Biomarker Pipeline (TransBioLine) and Neurotoxicity De-Risking in Preclinical Drug Discovery (NeuroDeRisk).

Methods

Performance of fluid-based NS injury biomarker candidates neurofilament light chain (NF-L), glial fibrillary acidic protein (GFAP), neuron specific enolase (NSE) and total Tau in plasma and cerebrospinal fluid (CSF) was evaluated in 15 rat in vivo studies. Model nervous system toxicants as well as other compounds were used to evaluate sensitivity and specificity. Histopathologic assessments of nervous tissues and behavioral observations were conducted to detect and characterize NS injuries. Receiver operator characteristic (ROC) curves were generated to compare the relative performance of the biomarkers in their ability to detect NS injury.

Results

NF-L was the best performer in detecting both peripheral nervous system (PNS) and CNS injury in plasma, (AUC of 0.97-0.99; respectively). In CSF, Tau correlated the best with CNS (AUC 0.97), but not PNS injury. NSE and GFAP were suitable for monitoring CNS injury, but with lesser sensitivity. In summary, NF-L is a sensitive and specific biomarker in rats for detecting compound-induced central and peripheral NS injuries. While NF-L measurement alone cannot inform the site of the injury, addition of biomarkers like Tau and NSE and analysis in both blood and CSF can provide additional information about the origin of the NS injury.

Conclusion

These results demonstrate the utility of emerging safety biomarkers of drug-induced NS injury in rats and provide additional supporting evidence for biomarker translation across species and potential use in clinical settings to monitor drug-induced NS injury in patients.

Elevated plasma neurofilament light chain in immune-mediated neurological disorders (IMND) detected by immunomagnetic reduction (IMR)

BACKGROUND

In cases of immune-mediated neurological disorders (IMND), different syndromes are associated with antibodies against neuronal surface antigens, intra-neuronal antigens, astrocytic aquaporin, and gangliosides. These autoantibodies can be pathogenic or connected to neuroinflammation and resulting neuronal injuries. This study aims to identify a blood biomarker that can detect neuronal damage in individuals with IMND. To this end, we use immunomagnetic reduction (IMR) nanobead technology to measure plasma neurofilament light chain (NfL).

METHODS

The patients with IMND were enrolled in the Chang Gung Memorial Hospital at Keelung from 2018 to 2023. Seronegative patients were excluded based on the results of antibody tests. The healthy controls (HC) were community-dwelling adults from the Northeastern Taiwan Community Medicine Research Cohort (NTCMRC) conducted by the Community Medicine Research Center of the Keelung CGMH from 2020 to 2022. IMR technique detects magnetic susceptibility via measuring magnetic signal reduction caused by antigen-antibody immunocomplex formation on magnetic nanobeads. The plasma level of NfL was determined by the magnetic susceptibility changes in IMR.

RESULTS

The study enrolled 57 IMND patients from the hospital and 73 HC participants from the communities. The plasma NfL was significantly higher in the IMND than in the HC (11.022 ± 2.637 vs. 9.664 ± 2.610 pg/mL, p = 0.004), regardless of age effects on plasma NfL in an analysis of covariance (ANCOVA) (F = 0.720, p = 0.950). In the receiver of operation curve analysis, the area under curve for plasma NfL to discriminate IMND and HC was 0.664 (95% CI = 0.549 to 0.739, p = 0.005). The subgroup analysis of plasma NfL in the IMND patients showed no difference between peripheral immune-mediated neuropathy (IMN) and central immune-mediated encephalomyelitis (IMEM) (11.331 ± 2.895 vs. 10.627 ± 2.260 pg/mL, p = 0.322), nor between tumor and non-tumor IMND (10.784 ± 3.446 vs. 11.093 ± 2.391 pg/mL, p = 0.714). Additionally, the antibody class of ganglioside antibodies in IMN did not have an impact on plasma NfL level (p = 0.857).

CONCLUSION

Plasma NfL measurement is a reliable indicator of axonal injuries in patients with IMND. It is equally effective in detecting nerve injuries in inflammatory peripheral neuropathies and central neuroinflammation. The IMR nanobead technology offers a feasible method of detecting plasma NfL, which helps identify axonal injuries in IMND.