CSF Neurofilament Light Chain Research Articles

Blood biomarkers for Alzheimer’s disease with the Lumipulse automated platform: Age-effect and clinical value interpretation

BackgroundAdvances in analytical methods have recently paved the way to Alzheimer’s disease (AD) biomarkers testing in blood along with the more established CSF testing. To ensure a forthcoming application of this low-invasive diagnostic that might allow to recognize early onset of dementia, appropriate pathological cut-points need to be defined. MethodsIn this cross-sectional study we measured blood and CSF neurofilament light chain (NFL), phosphorylated tau (pTau 181), Amyloid-β1-42 (AB 1–42) and Amyloid-β1-40 (AB 1–40) on a fully automated chemiluminescent platform (Lumipulse, Fujirebio) in 80 cognitively impaired patients and 55 cognitively unimpaired subjects. Clinical cut points were calculated with receiver-operator characteristic (ROC) curve analysis and a head-to-head comparison of blood and CSF testing was performed. ResultsBlood NFL best discriminant thresholds to distinguish neurodegenerative diseases from controls varied age-dependently, being 19 and 33 pg/mL in subjects 50–65 years and > 65 years respectively. AD was best framed by AB 1–42/1–40 ratio < 0.079 and ptau181 > 1 pg/mL. Though a strong correlation for all biomarkers, only blood AB ratio was equal to CSF testing for AD diagnosis. ConclusionsThe specific context of use might be considered to define the cut-offs of blood biomarkers of neurodegenerative diseases. Future efforts towards reference materials for each AD blood biomarker will improve clinical cut-offs.

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.

Progression predictors of clinically isolated syndrome to multiple sclerosis: A prospective study in China

ObjectivesClinically isolated syndrome (CIS) is a preclinical phase of multiple sclerosis (MS). The progression rate of CIS to clinical definite MS (CDMS) varies significantly across different populations, and identifying predictors of progression is crucial for early diagnosis and treatment. We aimed to investigate predictors of progression from CIS to CDMS in a Chinese cohort. MethodsA single-center cohort study was conducted with newly diagnosed patients with CIS in China between 2018 and 2021. All patients underwent a comprehensive clinical evaluation, including neurological examination, magnetic resonance imaging, and laboratory tests. Follow-up assessments were conducted at regular intervals to monitor disease progression. Progression to CDMS was defined according to the 2017 McDonald criteria. Age, sex, Expanded Disability Status Scale (EDSS) score, number of patients with magnetic resonance imaging gadolinium-enhancing (Gd+) lesions, T2 lesions and Gd+ lesions count, CSF cell count, CSF total protein, CSF and serum neurofilament light chain (NfL), progranulin (PGRN) and Th17-related cytokines (IL-6, IL-17, IL-21, IL-22, IL-23 and TGF-β) were measured for association with risk of progression to CDMS. ResultsA total of 96 CIS patients were recruited in the study. During the at least 24 months follow-up period, 57 (59.38 %) CIS patients progressed to CDMS, while 39 (40.62 %) patients without progression remained stable as CIS. Multivariate analysis revealed that younger age at onset (OR= 43.43, 95 % CI= 1.76–1071.68, p<0.021), higher CSF elevated protein (OR=58.64, 95 % CI=2.72–1264.51, p=0.009), higher CSF NfL levels (OR= 97.00, 95 % CI= 4.68–2012.99, p=0.003) and higher CSF IL-23 levels (OR= 412.02, 95 % CI=6.56–25869.60, p=0.004) were associated with high risk of progression to CDMS. ConclusionYounger age at onset, elevated CSF NfL, IL-23 and protein levels might be progression predictors of CIS to CDMS in Chinese population.

Increased CXCL12, a potential CSF biomarker for differential diagnosis of amyotrophic lateral sclerosis

Abstract Amyotrophic lateral sclerosis (ALS) is a debilitating and lethal neurodegenerative disorder marked by the gradual deterioration of motor neurons. Diagnosing ALS is challenging due to the lack of reliable diagnostic tools, with clinical assessment being the primary criterion. Recently, increased levels of neurofilament light chain (NF-L) in CSF have been considered a useful biomarker in disease, correlating with disease progression but not specific for diagnosis. This study utilized ELISA to measure CSF CXCL12 levels in healthy controls (HC), ALS patients, and patients with ALS-mimic disorders, assessing its potential as a diagnostic biomarker and comparing it with NF-L levels. Our results confirmed previous findings, showing increased CXCL12 levels in ALS patients compared to HC (797.07 ± 31.84 pg/mL vs. 316.15 ± 16.6 pg/mL; p=0.000) and increased CSF NF-L levels in ALS (4,565.63 ± 263.77 pg/mL) compared to HC (847.86 ± 214.37 pg/mL; p=0.000). Increased CXCL12 levels were specific to ALS, not seen in ALS-mimic conditions like myelopathies (252.20 ± 23.16 pg/mL; p=0.000), inflammatory polyneuropathies (IP) (270.24 ± 32.23 pg/mL; p=0.000), and other mimic diseases (OMD) (228.91 ± 29.20 pg/mL; p=0.000). In contrast, CSF NF-L levels in ALS overlapped with those in myelopathies (2,900.11 ± 872.20 pg/mL; p=0.821) and OMD (3,169.75 ± 1,096.65 pg/mL; p=0.63), but not with IP (1,156.4 ± 356.6 pg/mL; p=0.000). ROC curve analysis indicated significant differences between the AUC values of CXCL12 and NF-L in their diagnostic capacities. CXCL12 could differentiate between ALS and myelopathies (AUC: 0.99 ± 0.005), IP (AUC: 0.962 ± 0.027), and OMD (AUC: 1.00 ± 0.00), whereas NF-L was only effective in IP cases (AUC: 0.92 ± 0.048), not in myelopathies (AUC: 0.71 ± 0.09) or OMD (AUC: 0.69 ± 0.14). We also evaluated CXCL12 levels in plasma (ALS (2,022 ± 81.8 pg/mL) vs HC (1,739.43 ± 77.3 pg/mL; p=0.015)) but found CSF determination (AUC: 0.97 ± 0.012) to be more accurate than plasma determination (AUC: 0.65 ± 0.063). In plasma, SIMOA NF-L determination (ALS (86.00 ± 12.23 pg/mL) vs HC (12.69 ± 1.15 pg/mL); p=0.000) was more accurate than plasma CXCL12 (AUC: 0.98 ± 0.01405). These findings suggest that CSF CXCL12 levels can enhance diagnostic specificity in distinguishing ALS from ALS-mimic disorders, compared to NF-L. Larger studies are needed to validate these results, but CXCL12 determination shows promising diagnostic potential.

Biochemical, Biomarker, and Behavioral Characterization of the GrnR493X Mouse Model of Frontotemporal Dementia.

Heterozygous loss-of-function mutations in the progranulin gene (GRN) are a major cause of frontotemporal dementia due to progranulin haploinsufficiency; complete deficiency of progranulin causes neuronal ceroid lipofuscinosis. Several progranulin-deficient mouse models have been generated, including both knockout mice and knockin mice harboring a common patient mutation (R493X). However, the GrnR493X mouse model has not been characterized completely. Additionally, while homozygous GrnR493X and Grn knockout mice have been extensively studied, data from heterozygous mice is still limited. Here, we performed more in-depth characterization of heterozygous and homozygous GrnR493X knockin mice, which includes biochemical assessments, behavioral studies, and analysis of fluid biomarkers. In the brains of homozygous GrnR493X mice, we found increased phosphorylated TDP-43 along with increased expression of lysosomal genes, markers of microgliosis and astrogliosis, pro-inflammatory cytokines, and complement factors. Heterozygous GrnR493X mice did not have increased TDP-43 phosphorylation but did exhibit limited increases in lysosomal and inflammatory gene expression. Behavioral studies found social and emotional deficits in GrnR493X mice that mirror those observed in Grn knockout mouse models, as well as impairment in memory and executive function. Overall, the GrnR493X knockin mouse model closely phenocopies Grn knockout models. Lastly, in contrast to homozygous knockin mice, heterozygous GrnR493X mice do not have elevated levels of fluid biomarkers previously identified in humans, including neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) in both plasma and CSF. These results may help to inform pre-clinical studies that use this Grn knockin mouse model and other Grn knockout models.

CSF neurofilament light chain profiling and quantitation in neurological diseases.

Neurofilament light chain is an established marker of neuroaxonal injury that is elevated in CSF and blood across various neurological diseases. It is increasingly used in clinical practice to aid diagnosis and monitor progression and as an outcome measure to assess safety and efficacy of disease-modifying therapies across the clinical translational neuroscience field. Quantitative methods for neurofilament light chain in human biofluids have relied on immunoassays, which have limited capacity to describe the structure of the protein in CSF and how this might vary in different neurodegenerative diseases. In this study, we characterized and quantified neurofilament light chain species in CSF across neurodegenerative and neuroinflammatory diseases and healthy controls using targeted mass spectrometry. We show that the quantitative immunoprecipitation-tandem mass spectrometry method developed in this study strongly correlates to single-molecule array measurements in CSF across the broad spectrum of neurodegenerative diseases and was replicable across mass spectrometry methods and centres. In summary, we have created an accurate and cost-effective assay for measuring a key biomarker in translational neuroscience research and clinical practice, which can be easily multiplexed and translated into clinical laboratories for the screening and monitoring of neurodegenerative disease or acute brain injury.

Translatable plasma and CSF biomarkers for use in mouse models of Huntington's disease.

Huntington's disease is an inherited neurodegenerative disorder for which a wide range of disease-modifying therapies are in development and the availability of biomarkers to monitor treatment response is essential for the success of clinical trials. Baseline levels of neurofilament light chain in CSF and plasma have been shown to be effective in predicting clinical disease status, subsequent clinical progression and brain atrophy. The identification of further sensitive prognostic fluid biomarkers is an active research area, and total-Tau and YKL-40 levels have been shown to be increased in CSF from Huntington's disease mutation carriers. The use of readouts with clinical utility in the preclinical assessment of potential therapeutics should aid in the translation of new treatments. Here, we set out to determine how the concentrations of these three proteins change in plasma and CSF with disease progression in representative, well-established mouse models of Huntington's disease. Plasma and CSF were collected throughout disease progression from R6/2 transgenic mice with CAG repeats of 200 or 90 codons (R6/2:Q200 and R6/2:Q90), zQ175 knock-in mice and YAC128 transgenic mice, along with their respective wild-type littermates. Neurofilament light chain and total-Tau concentrations were quantified in CSF and plasma using ultrasensitive single-molecule array (Quanterix) assays, and a novel Quanterix assay was developed for breast regression protein 39 (mouse homologue of YKL-40) and used to quantify breast regression protein 39 levels in plasma. CSF levels of neurofilament light chain and plasma levels of neurofilament light chain and breast regression protein 39 increased in wild-type biofluids with age, whereas total-Tau remained constant. Neurofilament light chain and breast regression protein 39 were elevated in the plasma and CSF from Huntington's disease mouse models, as compared with wild-type littermates, at presymptomatic stages, whereas total-Tau was only increased at the latest disease stages analysed. Levels of biomarkers that had been measured in the same CSF or plasma samples taken at the latest stages of disease were correlated. The demonstration that breast regression protein 39 constitutes a robust plasma biomarker in Huntington's disease mouse models supports the further investigation of YKL-40 as a CSF biomarker for Huntington's disease mutation carriers. Neurofilament light chain and Tau are considered markers of neuronal damage, and breast regression protein 39 is a marker of inflammation; the similarities and differences in the levels of these proteins between mouse models may provide future insights into their underlying pathology. These data will facilitate the use of fluid biomarkers in the preclinical assessment of therapeutic agents for Huntington's disease, providing readouts with direct relevance to clinical trials.

Clinical value of CSF TMEM106B in familial and sporadic frontotemporal lobar degeneration

AbstractBackgroundTMEM106B, a lysosomal trafficking protein, is an important genetic susceptibility risk factor for frontotemporal lobar degeneration (FTLD). In GRN mutation carriers, minor allele homozygosity in the TMEM106B rs1990622 SNP modulates the risk of FTLD. TMEM106B is often the main component of amyloid fibrils in FTLD with TDP43 aggregates. TMEM106B has been quantified in human brain specimens, but its role as a fluid biomarker is unknown. Here, we investigate the clinical value of CSF TMEM106B in FTLD.MethodsCSF TMEM106B was quantified with SOMAmer proteomics (v3.0, SomaLogic®) in an original cohort of C9orf72, GRN and MAPT symptomatic and asymptomatic mutation carriers and family non‐carrier controls, recruited through ALLFTD (n = 182), and a validation cohort of sporadic neuropathology‐confirmed FTLD‐tau and FTLD‐TDP43, clinically‐diagnosed progressive supranuclear palsy – Richardson syndrome (PSP‐RS) and age‐matched controls (n = 96). CSF TMEM106B was correlated with disease severity, measured by the Frontotemporal Lobar Degeneration module global scores (CDR+NACC/FTLD); brain volume, measured with Bayesian linear mixed‐effect modeling, using age, sex and total‐intracranial volume‐corrected permutations with threshold‐free cluster enhancement; and CSF neurofilament light chain (NfL) measured with Simoa. TMEM106B SOMAmer specificity was validated in cell culture overexpression systems and human brain specimens with high TMEM106B burden.ResultsIn both cohorts, there were no differences in CSF TMEM106B by sex, phenotype or neuropathological diagnosis, except for lower levels in PSP‐RS compared to controls (‐0.31 Log2‐fold change, p &lt; 0.001). CSF TMEM106B did not correlate with age. Regardless of disease‐causing mutation, lower CSF TMEM106B was associated with worse disease severity (Figure 1 and 2). CSF TMEM106B was lower in homozygous TMEM106B rs1990622 protective allelein C9orf2 and MAPT, but not in GRN mutation carriers (Figures 3). CSF TMEM106B showed a trend for inverse correlation with NfL in the whole sample (r = ‐0.135, p = 0.052), and correlated positively with left frontal volume in symptomatic FTLD mutation gene carriers (p &lt; 0.05).ConclusionCSF TMEM106B is quantifiable in CSF in vivo. CSF TMEM106B levels are affected by an interaction of disease severity and FTLD and TMEM106B genotypes. Further work is needed to determine its value as a clinical biomarker.

Evaluation of serum and cerebrospinal fluid biomarkers after vaccination against SARS-CoV-2.

Vaccines are a major achievement of science, and new vaccines against SARS-CoV-2 are protecting the entire population from a life-threatening infection. Although several neurological complications or worsening of pre-existing neurological conditions after vaccination have been observed, whether a biological plausibility exist between new vaccines against-SARS-CoV-2 and neurological consequences is unclear. The aim of this study is to evaluate whether vaccines against SARS-CoV-2 induce systemic or cerebrospinal fluid alterations in patients with neurological disorders. Patients who underwent lumbar puncture (LP) between February 2021 and October 2022 were enrolled. Serum C-reactive protein (CRP), neutrophil to lymphocyte ratio (NLR), cerebrospinal fluid total protein content (CSF-TPc), glucose CSF/serum ratio, number of CSF cells per cubic millimeter, and CSF neurofilament light chain (CSF-NfL) were compared between unvaccinated and vaccinated patients. A total of 110 patients were included and fitted into three groups according firstly to vaccination status (vaccinated and unvaccinated) and then to time from last dose of vaccine to LP (within or after 3 months). TPc, CSF/SGlu ratio, number of cells per cubic millimeter, CSF-NfL, CRP, and NLR were not different between groups (all p > 0.05), and also, they did not differ neither according to age nor diagnosis. No relevant differences between groups were also noticed when the at-risk time window was set to 6 weeks. No signs of neuroinflammation, axonal loss and systemic inflammation were found in patients with neurological disorders after anti-SARS-CoV-2 vaccination compared with unvaccinated ones.

Serum neurofilament light chain (NfL)and CSF glial fibrillary acidic protein (GFAP) together improve the prediction of long-term clinical outcomes in multiple sclerosis (S9.001)

Serum neurofilament light chain (NfL)and CSF glial fibrillary acidic protein (GFAP) together improve the prediction of long-term clinical outcomes in multiple sclerosis (S9.001)

Predicting CSF neurogranin and neurofilament light chain protein levels with a neuropathology‐based APOE genetic risk score

AbstractBackgroundCerebrospinal fluid (CSF) levels of neurogranin, an index of synaptic degeneration, and neurofilament light chain (NfL), an index of neuroaxonal degradation, are both biomarkers of neurodegeneration in Alzheimer’s disease (AD). The presence of APOE is the strongest genetic risk factor for late onset AD and has also been associated with increased CSF neurogranin, a marker of neurodegeneration. To test the association between APOE and CSF biomarkers for neurodegeneration, we used a neuropathology‐based weighted risk score for APOE genotype (APOE‐npscore) and hypothesized that greater AD risk as indexed by the APOE‐npscore would be associated with higher CSF concentrations of neurogranin and NfL.MethodWe examined data collected from participants in the Wisconsin Registry for Alzheimer’s Prevention (n = 243) (avg age = 65) and Wisconsin Alzheimer’s Disease Research Center (n = 411) (avg age = 64) including participants with Dementia (n = 50) Impaired‐Other (n = 8), Mild Cognitive Impairment (MCI) (n = 55), and cognitively unimpaired (n = 545) participants. The CSF biomarkers were measured using the NeuroToolKit panel of robust prototype assays (Roche Diagnostics International Ltd, Rotkreuz, Switzerland). Using linear regression, we tested associations between the APOE‐npscore and CSF neurogranin and NfL concentrations, adjusting for age at lumbar puncture (LP) and sex. We also tested for interactions between age at LP or sex and the APOE‐npscore.ResultsThe APOE‐npscore was significantly associated with CSF neurogranin concentration (β = 3.126, p &lt; 0.01) but not significantly associated with CSF NfL concentration (β = 39.570, p &gt; 0.05). Age at LP was significantly associated (p &lt; 0.001) with CSF neurogranin and NfL concentrations. No significant interactions were found between the APOE‐np score and age at LP or sex in either test. APOE‐npscore, age at LP, and sex accounted for 7% of the variability of CSF neurogranin, and 27% of CSF NfL.ConclusionsThe current study lends additional support to the impact of APOE on neurodegeneration, and supports the utility of using the APOE‐npscore to index risk of AD. The effects of APOE were observed on markers of synaptic degeneration, which underscores the importance of synaptic dysfunction in AD.

Neurofilament light levels predict clinical progression and death in multiple system atrophy.

Disease-modifying treatments are currently being trialled in multiple system atrophy. Approaches based solely on clinical measures are challenged by heterogeneity of phenotype and pathogenic complexity. Neurofilament light chain protein has been explored as a reliable biomarker in several neurodegenerative disorders but data on multiple system atrophy have been limited. Therefore, neurofilament light chain is not yet routinely used as an outcome measure in multiple system atrophy. We aimed to comprehensively investigate the role and dynamics of neurofilament light chain in multiple system atrophy combined with cross-sectional and longitudinal clinical and imaging scales and for subject trial selection. In this cohort study, we recruited cross-sectional and longitudinal cases in a multicentre European set-up. Plasma and CSF neurofilament light chain concentrations were measured at baseline from 212 multiple system atrophy cases, annually for a mean period of 2 years in 44 multiple system atrophy patients in conjunction with clinical, neuropsychological and MRI brain assessments. Baseline neurofilament light chain characteristics were compared between groups. Cox regression was used to assess survival; receiver operating characteristic analysis to assess the ability of neurofilament light chain to distinguish between multiple system atrophy patients and healthy controls. Multivariate linear mixed-effects models were used to analyse longitudinal neurofilament light chain changes and correlated with clinical and imaging parameters. Polynomial models were used to determine the differential trajectories of neurofilament light chain in multiple system atrophy. We estimated sample sizes for trials aiming to decrease neurofilament light chain levels. We show that in multiple system atrophy, baseline plasma neurofilament light chain levels were better predictors of clinical progression, survival and degree of brain atrophy than the neurofilament light chain rate of change. Comparative analysis of multiple system atrophy progression over the course of disease, using plasma neurofilament light chain and clinical rating scales, indicated that neurofilament light chain levels rise as the motor symptoms progress, followed by deceleration in advanced stages. Sample size prediction suggested that significantly lower trial participant numbers would be needed to demonstrate treatment effects when incorporating plasma neurofilament light chain values into multiple system atrophy clinical trials in comparison to clinical measures alone. In conclusion, neurofilament light chain correlates with clinical disease severity, progression and prognosis in multiple system atrophy. Combined with clinical and imaging analysis, neurofilament light chain can inform patient stratification and serve as a reliable biomarker of treatment response in future multiple system atrophy trials of putative disease-modifying agents.

Validation of Plasma and CSF Neurofilament Light Chain as an Early Marker for Sporadic Creutzfeldt-Jakob Disease.

Biomarkers are becoming increasingly important for the differential diagnosis of neurodegenerative diseases. Previous observations indicated neurofilament light chain (NfL) as a potential blood-based biomarker for sporadic Creutzfeldt-Jakob disease (sCJD). Here, we investigated the stability, inter-assay/intra-assay variation and the regulation of NfL levels in CSF and plasma in a large cohort of sCJD patients by using a single-molecule array (SIMOA). We defined cutoffs for an accurate diagnosis and measured plasma NfL level in prion-infected mice models at different time points to identify the potential dynamics throughout the disease. Our analyses confirmed CSF and plasma NfL as stable and consistent marker for sCJD. Receiver operating characteristic (ROC) curve analysis showed an AUC of 0.92-0.93 to distinguish sCJD from control groups. Newly defined cutoffs revealed good diagnostic accuracies of CSF and plasma NfL, indicated by a sensitivity of 80-83.5% and a specificity of 87.4-91%. Studies on two humanized prion-infected mice lines (Tg340-PRNP129MM and Tg361-PRNP129VV) revealed increased plasma NfL levels in a late pre-clinical or very early clinical stage between 120-150days post-inoculation. In conclusion, our work supports the potential use of CSF and plasma NfL as a very early biomarker in sCJD diagnostic with good diagnostic accuracies.

Neurofilament Light Chain Levels in Multiple Sclerosis Correlate With Lesions Containing Foamy Macrophages and With Acute Axonal Damage.

Background and ObjectivesTo investigate whether white matter lesion activity, acute axonal damage, and axonal density in MS associate with CSF neurofilament light chain (NfL) levels.MethodsOf 101 brain donors with MS (n = 92 progressive MS, n = 9 relapsing-remitting MS), ventricular CSF was collected, and NfL levels were measured. White matter lesions were classified as active, mixed, inactive, or remyelinated, and microglia/macrophage morphology in active and mixed lesions was classified as ramified, ameboid, or foamy. In addition, axonal density and acute axonal damage were assessed using Bielschowsky and amyloid precursor protein (APP) (immune)histochemistry.ResultsCSF NfL measurements of donors with recent (<1 year) or clinically silent stroke were excluded. CSF NfL levels correlated negatively with disease duration (p = 6.9e-3, r = 0.31). In donors without atrophy, CSF NfL levels correlated positively with the proportion of active and mixed lesions containing foamy microglia/macrophages (p = 9.85e-10 and p = 1.75e-3, respectively), but not with those containing ramified microglia. CSF NfL correlated negatively with proportions of inactive (p = 5.66e-3) and remyelinated lesions (p = 0.03). In the normal appearing pyramid tract, axonal density negatively correlated with CSF NfL levels (Bielschowsky, p = 0.02, r = −0.31), and the presence of acute axonal damage in lesions was related to higher NfL levels (APP, p = 1.17e-6). The amount of acute axonal damage was higher in active lesions with foamy microglia/macrophages and in the rim of mixed lesions with foamy microglia/macrophages when compared with active lesions containing ramified microglia/macrophages (p = 4.6e-3 and p = 0.02, respectively), the center and border of mixed lesions containing ramified microglia/macrophages (center: p = 4.6e-3, border, p = 4.6e-3, and n.s., p = 4.6e-3, respectively), the center of mixed lesions containing foamy microglia/macrophages (p = 4.6e-3 and p = 0.02, respectively), inactive lesions (p = 4.6e-3 and p = 4.6e-3, respectively), and remyelinated lesions (p = 0.03 and p = 0.04, respectively).DiscussionOur results demonstrated that active and mixed white matter MS lesions with foamy microglia show high acute axonal damage and correlate with elevated CSF NfL levels. Our data support the use of this biomarker to monitor inflammatory demyelinating lesion activity with axonal damage in MS.

Cerebrospinal fluid analysis in patients with COVID-19-associated central nervous system manifestations: a systematic review.

Central nervous system (CNS) symptoms may occur in patients with acute COVID-19. The role of CSF examination in these patients remains to be established. A systematic review of CSF findings relating to COVID-19 was carried out. CSF parameters, including cytological and biochemical analyses, SARS-CoV-2 RT-PCR and other CSF markers, were recorded and analyzed among patients with acute COVID-19 and one of the following CNS syndromes: stroke, encephalopathy, encephalitis, inflammatory syndromes, seizure, headache and meningitis. Increased white blood cells and/or increased protein concentration were found in 52.7% of the patients with encephalitis, 29.4% of the patients with encephalopathy and 46.7% of the patients with inflammatory syndromes (P < 0.05). CSF RT-PCR for SARS-CoV-2 was positive in 17.35% of the patients with encephalitis and less than 3.5% of the patients with encephalopathy or inflammatory syndromes (P < 0.05). Intrathecal production of immunoglobulins was found in only 8% of the cases. More than 85% of the patients had increased CSF cytokines and chemokines. Increased CSF neurofilament light chain (NfL) and CSF Tau were found in 71% and 36% of the cases, respectively. Non-specific inflammatory CSF abnormalities were frequently found in patients with COVID-19 CNS syndromes. The increase in neurodegeneration biomarkers suggests that neuronal damage occurs, with long-term consequences that are still unknown.

Fibrillar Aβ causes profound microglial metabolic perturbations in a novel APP knock-in mouse model.

Microglial dysfunction is believed to play a pathogenic role in Alzheimer's disease (AD). Microglia respond to various pathogenic drivers of AD, including amyloid-ß (Aß) and tau, but the mechanisms by which microglia may become dysfunctional and contribute to disease remain unclear. Here, we aim to characterize the amyloid-ß related pathology and microglial responses in an engineered APP knock-in mouse model of familial AD (AppSAA ). To circumvent the numerous limitations inherent to transgenesis, we used a knock-in strategy to humanize the Aß sequence of the murine App gene and introduced three FAD mutations - Swedish (KM670/671NL), Arctic (E693G) and Austrian (T712I) - using homologous recombination. We then conducted an extensive biochemical and histological characterization of various tissues from the three resulting genotypes at various ages. Finally, we conducted a deep-phenotyping analysis of brain-sorted microglia using multi-omics approaches. The AppSAA knock-in mouse model recapitulates key pathological features of AD such as a progressive accumulation of parenchymal amyloid plaques and vascular amyloid deposits, altered glial responses and increased levels of markers of neurodegeneration such as CSF Tau and neurofilament light chain. We found lipid accumulation and an exacerbated disease-associated transcriptomic response in methoxy-X04-positive, phagocytic microglia. Altogether, our in-depth analysis of the AppSAA knock-in mouse model confirms emergence of disease-relevant biology and progressive accumulation of pathological hallmarks of AD. Our data lends further support to the notion that phagocytic microglia undergo profound cellular alterations, including lysosomal dysfunction, lipid dyshomeostasis, and other metabolic changes. Since this new mouse model can be used to investigate multiple relevant aspects of AD biology, we have made it broadly available to the scientific community.

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

Aim: The aim of the present metanalysis is to evaluate blood and CSF Neurofilament light chain (NfL) concentrations in ALS patients, compared to healthy controls, ALS mimic disorders (ALSmd) and other neurological diseases (OND), and to evaluate their diagnostic yield against ALSmd. Methods: Search engines were systematically investigated for relevant studies. A random effect model was applied to estimate the pooled standard mean difference in NfL levels between ALS and controls and a bivariate mixed-effects model was applied to estimate their diagnostic accuracy on blood and CSF. Results and conclusions: NfL CSF levels were higher in ALS compared with all other control groups. On blood, NfL levels were significantly higher in ALS patients compared with healthy controls and ALSmd. In a subgroup analysis, the use of SIMOA yielded to a better differentiation between ALS and controls on blood, compared with ELISA. Studies performed on CSF (AUC = 0.90) yielded to better diagnostic performances compared with those conducted on blood (AUC = 0.78). Further prospective investigations are needed to determine a diagnostic cutoff, exploitable in clinical practice.

A data-driven disease progression model of fluid biomarkers in genetic frontotemporal dementia.

Several CSF and blood biomarkers for genetic frontotemporal dementia have been proposed, including those reflecting neuroaxonal loss (neurofilament light chain and phosphorylated neurofilament heavy chain), synapse dysfunction [neuronal pentraxin 2 (NPTX2)], astrogliosis (glial fibrillary acidic protein) and complement activation (C1q, C3b). Determining the sequence in which biomarkers become abnormal over the course of disease could facilitate disease staging and help identify mutation carriers with prodromal or early-stage frontotemporal dementia, which is especially important as pharmaceutical trials emerge. We aimed to model the sequence of biomarker abnormalities in presymptomatic and symptomatic genetic frontotemporal dementia using cross-sectional data from the Genetic Frontotemporal dementia Initiative (GENFI), a longitudinal cohort study.Two-hundred and seventy-five presymptomatic and 127 symptomatic carriers of mutations in GRN, C9orf72 or MAPT, as well as 247 non-carriers, were selected from the GENFI cohort based on availability of one or more of the aforementioned biomarkers. Nine presymptomatic carriers developed symptoms within 18 months of sample collection (‘converters’). Sequences of biomarker abnormalities were modelled for the entire group using discriminative event-based modelling (DEBM) and for each genetic subgroup using co-initialized DEBM. These models estimate probabilistic biomarker abnormalities in a data-driven way and do not rely on previous diagnostic information or biomarker cut-off points. Using cross-validation, subjects were subsequently assigned a disease stage based on their position along the disease progression timeline.CSF NPTX2 was the first biomarker to become abnormal, followed by blood and CSF neurofilament light chain, blood phosphorylated neurofilament heavy chain, blood glial fibrillary acidic protein and finally CSF C3b and C1q. Biomarker orderings did not differ significantly between genetic subgroups, but more uncertainty was noted in the C9orf72 and MAPT groups than for GRN. Estimated disease stages could distinguish symptomatic from presymptomatic carriers and non-carriers with areas under the curve of 0.84 (95% confidence interval 0.80–0.89) and 0.90 (0.86–0.94) respectively. The areas under the curve to distinguish converters from non-converting presymptomatic carriers was 0.85 (0.75–0.95).Our data-driven model of genetic frontotemporal dementia revealed that NPTX2 and neurofilament light chain are the earliest to change among the selected biomarkers. Further research should investigate their utility as candidate selection tools for pharmaceutical trials. The model’s ability to accurately estimate individual disease stages could improve patient stratification and track the efficacy of therapeutic interventions.

Clinico-genetic findings in 509 frontotemporal dementia patients

Frontotemporal dementia (FTD) is a clinically and genetically heterogeneous disorder. To which extent genetic aberrations dictate clinical presentation remains elusive. We investigated the spectrum of genetic causes and assessed the genotype-driven differences in biomarker profiles, disease severity and clinical manifestation by recruiting 509 FTD patients from different centers of the German FTLD consortium where individuals were clinically assessed including biomarker analysis. Exome sequencing as well as C9orf72 repeat analysis were performed in all patients. These genetic analyses resulted in a diagnostic yield of 18.1%. Pathogenic variants in C9orf72 (n = 47), GRN (n = 26), MAPT (n = 11), TBK1 (n = 5), FUS (n = 1), TARDBP (n = 1), and CTSF (n = 1) were identified across all clinical subtypes of FTD. TBK1-associated FTD was frequent accounting for 5.4% of solved cases. Detection of a homozygous missense variant verified CTSF as an FTD gene. ABCA7 was identified as a candidate gene for monogenic FTD. The distribution of APOE alleles did not differ significantly between FTD patients and the average population. Male sex was weakly associated with clinical manifestation of the behavioral variant of FTD. Age of onset was lowest in MAPT patients. Further, high CSF neurofilament light chain levels were found to be related to GRN-associated FTD. Our study provides large-scale retrospective clinico-genetic data such as on disease manifestation and progression of FTD. These data will be relevant for counseling patients and their families.

Reader Response: CSF Biomarkers in Patients With COVID-19 and Neurologic Symptoms: A Case Series.

We read with interest the article by Edén et al.1 assessing the CSF biomarkers of intrathecal inflammation (CSF white blood cell counts, neopterin, β2-microglobulin [β2M], and immunoglobulin G index), blood-brain barrier integrity (albumin ratio), and axonal injury (CSF neurofilament light chain protein [NfL]) in COVID-19 patients with neurologic symptoms. The results illustrate evidence of significant CSF inflammation with raised soluble markers without any cellular response, unlike other viral CNS infections. As far as intrathecal markers such as neopterin and β2M are concerned, these are nonspecific and are produced by macrophages during the activation of cell-mediated immune response. These are often found significantly raised in various conditions such as HIV infection,2 relapsing-remitting or chronic progressive multiple sclerosis,3 and head trauma,4 putting forth questions about its value as a disease-specific marker.