Serum neurofilament light chain in patients with acute cerebrovascular events

Cerebral clues: serum neurofilament light chain (sNfL) as a novel biomarker for immune check point inhibitor (ICI) mediated seronegative encephalitis

Immune checkpoint inhibitor (ICI) mediated encephalitides are increasingly being recognized in the literature, but atypical cases may be missed or misdiagnosed. Recent efforts are directed to identify biomarkers to help elucidate early diagnosis and treatment. Herein, we describe two cases of antibody negative ICI-mediated encephalitis with elevated serum Neurofilament light chain (sNfL) levels. Practical Implication: Baseline and longitudinal measurements of serum neurofilament light chains can help determine treatment strategies and prognosis in patients with suspected immune checkpoint inhibitor encephalitis.

Serum neurofilament light chain: a predictive marker for outcomes following mild-to-moderate ischemic stroke

Background

Biomarkers that reflect brain damage or predict functional outcomes may aid in guiding personalized stroke treatments. Serum neurofilament light chain (sNfL) emerges as a promising candidate for fulfilling this role.

Methods

This prospective, observational cohort investigation included 319 acute ischemic stroke (IS) patients. The endpoints were the incidence of early neurological deterioration (END, an elevation of two or more points in the National Institute of Health stroke scale score within a week of hospitalization compared with the baseline) and functional outcome at 3 months (an mRS score of >2 at 3 months was categorized as an unfavorable/poor functional outcome). The association of sNfL, which was assessed within 24 h of admission, with END and unfavorable functional outcomes at follow-up was assessed via multivariate logistic regression, whereas the predictive value of sNfL for unfavorable functional outcomes and END was elucidated by the receiver operating characteristic curve (ROC).

Results

Of 319 IS individuals, 89 (27.90%) suffered from END. sNfL not only reflects the severity of stroke measured by NIHSS score (p < 0.05) but also closely related to the severity of age-related white matter changes. Higher initial NIHSS score, severe white matter lesions, diabetes mellitus, and upregulated sNfL were significant predictors of END. Similarly, the multivariate logistic regression analysis results showed that elevated sNfL, a higher baseline NIHSS score, and severe white matter lesions were substantially linked with unfavorable outcomes for 3 months. Similarly, sNfL was valuable for the prediction of the 3 months of poor outcome (95%CI, 0.504-0.642, p = 0.044). Kaplan-Meier analysis shows that patients with elevated sNfL levels are more likely to reach combined cerebrovascular endpoints (log-rank test p < 0.05).

Conclusion

This investigation suggests that sNfL can serve as a valuable biomarker for predicting END and 3-month poor functional outcomes after an IS and has the potential to forecast long-term cardiovascular outcomes.

Changes in plasma concentrations of novel vascular and inflammatory biomarkers in obstructive sleep apnea patients pre- and post-stroke

BACKGROUND

Obstructive sleep apnea (OSA) is increasingly recognized as a common condition in the general population and causes significant OSA-associated morbidities including cardiovascular and cerebrovascular events such as cerebral small vessel disease (CSVD) and stroke.

METHODS

In this study, using sensitive ELISA immunoassays, we measured subset of endothelial/vascular and inflammatory biomarkers as well as neurofilament light chain (NfL), a sensitive marker for neuroaxonal injury, using plasma from OSA patients post-stroke (Acute Cerebral Infarction (ACI), N = 26) to determine their usefulness as potential prognostic markers in disease progression.

RESULTS

Our results showed significantly increased plasma TNFα and NfL concentrations and decreased concentrations of platelet derived growth factor (PDGF-AA) in post-stroke OSA patients with more severe white matter hyperintensities (WMHs). And after separating the patients based on sex, compared to females, male post-stroke OSA patients with severe WMHs have increased circulating levels of inflammatory chemokine CXCL10 and cytokine Interleukin-10 (IL-10) and significantly decreased levels of Angiopoietin-1 (Ang-1) an important protein responsible for endothelial/vascular integrity functions. Importantly, in a subset of newly diagnosed OSA patients (without prior history of stroke), significantly increased plasma CXCL10 levels and decreased plasma Ang-1 levels were also readily observed when compared to healthy controls, indicating possible altered endothelial integrity and ongoing vascular inflammation in these newly diagnosed OSA patients.

CONCLUSIONS

In summary, our study has identified a novel set of plasma biomarkers including PDGF-AA, CXCL10 and Ang-1 for their potential prognostic value for disease outcomes pre- and post-stroke in OSA patients and use as surrogate markers to measure efficacy of treatment modalities.

Neurofilaments as biomarkers in neurological disorders - towards clinical application

Neurofilament proteins have been validated as specific body fluid biomarkers of neuro-axonal injury. The advent of highly sensitive analytical platforms that enable reliable quantification of neurofilaments in blood samples and simplify longitudinal follow-up has paved the way for the development of neurofilaments as a biomarker in clinical practice. Potential applications include assessment of disease activity, monitoring of treatment responses, and determining prognosis in many acute and chronic neurological disorders as well as their use as an outcome measure in trials of novel therapies. Progress has now moved the measurement of neurofilaments to the doorstep of routine clinical practice for the evaluation of individuals. In this Review, we first outline current knowledge on the structure and function of neurofilaments. We then discuss analytical and statistical approaches and challenges in determining neurofilament levels in different clinical contexts and assess the implications of neurofilament light chain (NfL) levels in normal ageing and the confounding factors that need to be considered when interpreting NfL measures. In addition, we summarize the current value and potential clinical applications of neurofilaments as a biomarker of neuro-axonal damage in a range of neurological disorders, including multiple sclerosis, Alzheimer disease, frontotemporal dementia, amyotrophic lateral sclerosis, stroke and cerebrovascular disease, traumatic brain injury, and Parkinson disease. We also consider the steps needed to complete the translation of neurofilaments from the laboratory to the management of neurological diseases in clinical practice.

Association between urinary glyphosate levels and serum neurofilament light chain in a representative sample of US adults: NHANES 2013-2014

BACKGROUND

Glyphosate, the herbicide with the highest global usage, has been found to have links to neurological impairment in some occupational studies. Neurofilament light chain (NfL) is a protein that is released into the bloodstream following neuroaxonal damage and has emerged as a reliable biomarker for various neurological disorders. However, no research has investigated the potential link between glyphosate exposure and neurological damage or serum NfL levels in the general population.

OBJECTIVE

The objective of this study was to assess the possible correlation between glyphosate exposure and serum NfL levels in a population that is representative of the United States.

METHODS

We analyzed data from 597 adults (aged ≥20 years) from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) to explore the potential correlation between urinary glyphosate levels and serum NfL levels.

RESULTS

We found a significant positive association between urinary glyphosate levels and serum NfL levels (ß-coefficient = 0.110; S.E. = 0.040; P = 0.015), indicating that higher levels of glyphosate exposure may be linked to higher levels of neuroaxonal damage. Furthermore, when glyphosate levels were divided into quintiles, we observed a significant trend of increasing mean NfL concentrations with increasing quintiles of glyphosate exposure (P for trend = 0.036). Notably, the association was more pronounced in certain subgroups, including those aged ≥40 years, non-Hispanic whites, and those with a BMI between 25 and 30.

IMPACT STATEMENT

This is the first research to suggest an association between glyphosate exposure and biomarkers indicative of neurological damage in general U.S. adults. If the correlation observed is causal, it raises concerns about the potential effects of glyphosate exposure on neurological health among U.S. adults. The study is noteworthy due to its representation of American adults aged 20 and above, as well as the use of reliable and comprehensive data from the NHANES database.

Biomarkers of Bipolar Disorder in Late Life: An Evidence-Based Systematic Review

PURPOSE OF REVIEW

Review the current evidence on biomarkers for bipolar disorder in the older adults. We conducted a systematic search of PubMed MEDLINE, PsycINFO, and Web of Science databases using the MeSH search terms "Biomarkers", "Bipolar Disorder", "Aged" and and "Aged, 80 and over". Studies were included if they met the following criteria: (1) the mean age of the study population was 50 years old or older, (2) the study included patients with bipolar disorder, and (3) the study examined one type of biomarkers or more including genetic, neuroimaging, and biochemical biomarkers. Reviews, case reports, studies not in English and studies for which no full text was available were excluded. A total of 26 papers were included in the final analysis.

RECENT FINDINGS

Genomic markers of bipolar disorder in older adults highlighted the implication of serotonin metabolism, while the expression of genes involved in angiogenesis was dysregulated. Peripheral blood markers were mainly related with low grade inflammation, axonal damage, endothelial dysfunction, and the dysregulation of the HPA axis. Neuroanatomical markers reflected a dysfunction of the frontal cortex, a loss of neurones in the anterior cingulate cortex and a reduction of the hippocampal volume (in patients older than 50 years old). While not necessarily limited to older adults, some of them may be useful for differential diagnosis (neurofilaments), disease staging (homocysteine, BDNF) and the monitoring of treatment outcomes (matrix metalloproteinases). Our review provides a comprehensive overview of the current evidence on biomarkers for bipolar disorder in the older adults. The identification of biomarkers may aid in the diagnosis, treatment selection, and monitoring of bipolar disorder in older adults, ultimately leading to improved outcomes for this population. Further research is needed to validate and further explore the potential clinical utility of biomarkers in this population.

Incremental value of serum neurofilament light chain and glial fibrillary acidic protein as blood-based biomarkers for predicting functional outcome in severe acute ischemic stroke

INTRODUCTION

Blood-based biomarkers may improve prediction of functional outcome in patients with acute ischemic stroke. The role of neurofilament light chain (NfL) and glial fibrillary acidic (GFAP) as potential biomarkers especially in severe stroke patients is unknown.

PATIENTS AND METHODS

Prospective, monocenter, cohort study including consecutive patients with severe ischemic stroke in the anterior circulation on admission (NIHSS score ⩾ 6 points or indication for mechanical thrombectomy). Outcome was assessed 3 months after the index stroke by the modified Rankin Scale (mRS). Serum biomarkers levels of NfL and GFAP were determined by ultrasensitive ELISA. Univariate and multivariate logistic regression models were performed to determine the association of biomarker levels and functional disability. Discrimination, calibration, and overall performance were analyzed in different models via AUROC, calibration plots (with Emax and Eavg), Brier-score and R2 using variables, identified as important covariates for functional outcome in previous studies.

RESULTS

Between 06/2020 and 08/2021, 213 patients were included [47% female, mean age 76 (SD ± 12) years, median NIHSS score 13 (interquartile range, IQR 9; 17)]. Biomarker serum levels were measured at a median of 1 [IQR, 1; 2] day after admission. Compared to patients with mRS 0-2 at 3 months, patients with mRS 3-6 had higher serum levels of NfL (median: 136 pg/ml vs 41 pg/ml; p < 0.0001) and GFAP (700 ng/ml vs 9.6 ng/ml; p < 0.0001). Both biomarkers were significantly associated with functional outcome [adjusted logistic regression, odds ratio (95% CI) for NfL: 2.63 (1.62; 4.56), GFAP: 2.16 (1.58; 3.09)]. In all models the addition of serum NfL led to a significant improvement in the AUROC, as did the addition of serum GFAP. Calibration plots showed high agreement between the predicted and observed outcomes and after addition of the two blood-based biomarkers there was an improvement of the overall performance.

CONCLUSION

Prediction of functional outcome after severe acute ischemic stroke was improved by the blood-based biomarkers serum NfL and GFAP, measured in the acute phase of stroke. These findings have to be replicated in independent external cohorts.Study registration: DRKS00022064.

Serum β-synuclein, neurofilament light chain and glial fibrillary acidic protein as prognostic biomarkers in moderate-to-severe acute ischemic stroke

We aimed to assess the prognostic value of serum β-synuclein (β-syn), neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) in patients with moderate-to-severe acute ischemic stroke. We measured β-syn, GFAP and NfL in serum samples collected one day after admission in 30 adult patients with moderate-to-severe ischemic stroke due to middle cerebral artery (MCA) occlusion. We tested the associations between biomarker levels and clinical and radiological scores (National Institute of Health Stroke Scale scores, NIHSS, and Alberta Stroke Program Early CT Score, ASPECTS), as well as measures of functional outcome (modified Rankin Scale, mRS). Serum biomarkers were significantly associated with ASPECTS values (β-syn p = 0.0011, GFAP p = 0.0002) but not with NIHSS scores at admission. Patients who received mechanical thrombectomy and intravenous thrombolysis showed lower β-syn (p = 0.029) und NfL concentrations (p = 0.0024) compared to patients who received only mechanical thrombectomy. According to median biomarker levels, patients with high β-syn, NfL or GFAP levels showed, after therapy, lower clinical improvement (i.e., lower 24-h NIHSS change), higher NIHSS scores during hospitalization and higher mRS scores at 3-month follow-up. Elevated serum concentrations of β-syn (p = 0.016), NfL (p = 0.020) or GFAP (p = 0.010) were significantly associated with 3-month mRS of 3-6 vs. 0-2 even after accounting for age, sex and renal function. In patients with moderate-to-severe acute ischemic stroke, serum β-syn, NfL and GFAP levels associated with clinical and radiological scores at different timepoints and were able to predict short- and middle-term clinical outcomes.

Serum neurofilament light chain levels in migraine patients: a monocentric case-control study in China

PURPOSE

Serum neurofilament light chain (sNfL) can reflect nerve damage. Whether migraine can cause neurological damage remain unclear. This study assesses sNfL levels in migraine patients and explores whether there is nerve damage in migraine.

METHODS

A case-control study was conducted in Xiamen, China. A total of 138 migraine patients and 70 healthy controls were recruited. sNfL (pg/mL) was measured on the single-molecule array platform. Univariate, Pearson correlation and linear regression analysis were used to assess the relationship between migraine and sNfL levels, with further subgroup analysis by migraine characteristics.

RESULTS

Overall, 85.10% of the 208 subjects were female, with a median age of 36 years. sNfL levels were higher in the migraine group than in the control group (4.85 (3.49, 6.62) vs. 4.11 (3.22, 5.59)), but the difference was not significant (P = 0.133). The two groups showed an almost consistent trend in which sNfL levels increased significantly with age. Subgroup analysis showed a significant increase in sNfL levels in patients with a migraine course ≥ 10 years (β = 0.693 (0.168, 1.220), P = 0.010). Regression analysis results show that age and migraine course are independent risk factors for elevated sNfL levels, and there is an interaction between the two factors. Patients aged < 45 years and with a migraine course ≥ 10 years have significantly increased sNfL levels.

CONCLUSIONS

This is the first study to evaluate sNfL levels in migraine patients. The sNfL levels significantly increased in patients with a migraine course ≥ 10 years. More attention to nerve damage in young patients with a long course of migraine is required.

Plasma Glial Fibrillary Acidic Protein and N-Terminal Pro B-Type Natriuretic Peptide: Potential Biomarkers to Differentiate Ischemic and Hemorrhagic Stroke

Acute stroke management is critically time-sensitive and challenging. Blood-based biomarkers that can differentiate acute ischemic stroke (IS) from hemorrhagic stroke (HS) can greatly facilitate triage and early management. Admission blood samples obtained within 6 h of stroke symptom onset were analyzed in a derivation/validation design. GFAP, N-FL, NT-proBNP, copeptin, neutrophils (%), NLR, and platelet counts were assessed in the derivation cohort. The informative markers and the derived cutoff values were evaluated in the validation cohort. GFAP > 703 pg/mL showed a PPV of 76.9% and NPV of 95.8% for differentiating HS from IS. Multiple logistic regression analysis showed that GFAP and NT-proBNP were independent variables associated with IS and HS differentiation. Furthermore, applying a combined cutoff (GFAP > 703 pg/mL and NT-proBNP ≤ 125 pg/mL) for HS detection increased the PPV in both the derivation and validation cohorts (93.3% and 100%, respectively). GFAP and NT-proBNP levels were validated as informative blood biomarkers in the differentiation of IS and HS and using a combination of GFAP and NT-proBNP is suggested as a feasible strategy to differentiate stroke subtypes in the hyperacute phase of stroke.

Urinary di-(2-ethylhexyl) phthalate metabolites are independently related to serum neurofilament light chain, a biomarker of neurological diseases, in adults: results from NHANES 2013-2014

Di (2-ethylhexyl) phthalate (DEHP) is a chemical commonly used in the manufacturing of plastics and can pose human health risks, including endocrine disruption, reproductive toxicity, and potential carcinogenic effects. Children may be particularly vulnerable to the harmful effects of DEHP. Early exposure to DEHP has been linked to potential behavioral and learning problems. However, there are no reports to date on whether DEHP exposure in adulthood has neurotoxic effects. Serum neurofilament light chain (NfL), a protein released into the blood after neuroaxonal damage, has been shown to be a reliable biomarker for many neurological diseases. To date, no study has examined the relationship between DEHP exposure and NfL. For the present study, we selected 619 adults (aged ≥ 20 years) from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) to examine the association between urinary DEHP metabolites and serum NfL. We reported higher urinary levels of ln-mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), ln-mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and ln-mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), and ln-ΣDEHP levels were associated with higher serum levels of ln-NfL (ΣDEHP: β-coefficient = 0. 075; S.E. = 0.026; P = 0.011). When we divided ΣDEHP into quartiles, mean NfL concentrations increased with quartiles of MEHHP (P for trend = 0.023). The association was more pronounced in males, non-Hispanic white race, higher income, and BMI < 25. In conclusion, higher DEHP exposure was positively associated with higher serum NfL in adults from NHANES 2013-2014. If this finding is causal, it is possible that DEHP exposure in adulthood may also induce neurological damage. Although the causality of this observation and the clinical significance are uncertain, our findings suggest that additional research is needed on DEHP exposure, serum NfL, and neurological disease in adults.

Serum neurofilament light chain levels are associated with early neurological deterioration in minor ischemic stroke

Objectives

Patients with minor ischemic stroke (MIS) frequently suffer from early neurological deterioration (END) and become disabled. Our study aimed to explore the association between serum neurofilament light chain (sNfL) levels and END in patients with MIS.

Methods

We conducted a prospective observational study in patients with MIS [defined as a National Institutes of Health Stroke Scale (NIHSS) score 0–3] admitted within 24 h from the onset of symptoms. sNfL levels were measured at admission. The primary outcome was END, defined as an increase in the NIHSS score by ≥2 points within 5 days after admission. Univariate and multivariate analyses were performed to explore the risk factors associated with END. Stratified analyses and interaction tests were conducted to identify variables that might modify the association between sNfL levels and END.

Results

A total of 152 patients with MIS were enrolled, of which 24 (15.8%) developed END. The median sNfL level was 63.1 [interquartile range (IQR), 51.2–83.4] pg/ml on admission, which was significantly higher than that of 40 age- and sex-matched healthy controls (median 47.6, IQR 40.8–56.1 pg/ml; p &lt; 0.001). Patients with MIS with END had a higher level of sNfL (with ND: median 74.1, IQR 59.5–89.8 pg/ml; without END: median 61.2, IQR 50.5–82.2 pg/ml; p = 0.026). After adjusting for age, baseline NIHSS score, and potential confounding factors in multivariate analyses, an elevated sNfL level (per 10 pg/mL) was associated with an increased risk of END [odds ratio (OR) 1.35, 95% confidence interval (CI) 1.04–1.77; p = 0.027). Stratified analyses and interaction tests demonstrated that the association between sNfL and END did not change by age group, sex, baseline NIHSS score, Fazekas' rating scale, hypertension, diabetes mellitus, intravenous thrombolysis, and dual antiplatelet therapy in patients with MIS (all p for interaction &gt; 0.05). END was associated with an increased risk of unfavorable outcomes (modified Rankin scale score ranging from 3 to 6) at 3 months.

Conclusion

Early neurological deterioration is common in minor ischemic stroke and is associated with poor prognosis. The elevated sNfL level was associated with an increased risk of early neurological deterioration in patients with minor ischemic stroke. sNfL might be a promising biomarker candidate that can help to identify patients with minor ischemic stroke at high risk of neurological deterioration, for reaching individual therapeutic decisions in clinical practice.

Plasma neurofilament light is a predictor of neurological outcome 12 h after cardiac arrest

BACKGROUND

Previous studies have reported high prognostic accuracy of circulating neurofilament light (NfL) at 24-72 h after out-of-hospital cardiac arrest (OHCA), but performance at earlier time points and after in-hospital cardiac arrest (IHCA) is less investigated. We aimed to assess plasma NfL during the first 48 h after OHCA and IHCA to predict long-term outcomes.

METHODS

Observational multicentre cohort study in adults admitted to intensive care after cardiac arrest. NfL was retrospectively analysed in plasma collected on admission to intensive care, 12 and 48 h after cardiac arrest. The outcome was assessed at two to six months using the Cerebral Performance Category (CPC) scale, where CPC 1-2 was considered a good outcome and CPC 3-5 a poor outcome. Predictive performance was measured with the area under the receiver operating characteristic curve (AUROC).

RESULTS

Of 428 patients, 328 (77%) suffered OHCA and 100 (23%) IHCA. Poor outcome was found in 68% of OHCA and 55% of IHCA patients. The overall prognostic performance of NfL was excellent at 12 and 48 h after OHCA, with AUROCs of 0.93 and 0.97, respectively. The predictive ability was lower after IHCA than OHCA at 12 and 48 h, with AUROCs of 0.81 and 0.86 (p ≤ 0.03). AUROCs on admission were 0.77 and 0.67 after OHCA and IHCA, respectively. At 12 and 48 h after OHCA, high NfL levels predicted poor outcome at 95% specificity with 70 and 89% sensitivity, while low NfL levels predicted good outcome at 95% sensitivity with 71 and 74% specificity and negative predictive values of 86 and 88%.

CONCLUSIONS

The prognostic accuracy of NfL for predicting good and poor outcomes is excellent as early as 12 h after OHCA. NfL is less reliable for the prediction of outcome after IHCA.

Neurofilament light is associated with clinical outcome and hemorrhagic transformation in moderate to severe ischemic stroke

Background

Ischemic stroke is a leading cause of morbidity and mortality worldwide. One possible predictor is the use of biomarkers especially neurofilament light chain (NFL).

Objectives

To explore whether NFL could predict clinical outcome and hemorrhagic transformation in moderate to severe stroke.

Design

Single center prospective cohort study.

Methods

Fifty-one moderate to severe ischemic stroke patients were recruited. Blood NFL was obtained from patients at admission (First sample) and 24-96 hours later (Second sample). NFL was analyzed with the ultrasensitive single molecule array (Simoa). Later, we calculated incremental rate NFL (IRN) by changes in NFL per day from baseline. We evaluated National Institute of Health stroke scale (NIHSS), modified Rankins score (mRs), and the presence of hemorrhagic transformation (HT).

Results

IRN was found to be higher in patients with unfavorable outcome (7.12 vs 24.07, P = .04) as well as Second sample (49.06 vs 71.41, P = .011), while NFL First sample was not significant. IRN had a great correlation with mRS (r = .552, P < .001). Univariate logistic regression model showed OR of IRN and Second sample to be 1.081 (95% CI 1.016-1.149, P = .013) and 1.019 (1.002-1.037, P = .03), respectively. Multiple logistic regression model has shown to be significant. In receiver operating analysis, IRN, Second sample, combined IRN with NIHSS and combined Second sample with NIHSS showed AUC (.744, P = .004; 0.713, P = .01; 0.805, P < .001; 0.803, P < .001, respectively). For HT, First sample and Second sample had significant difference with HT (Z = 2.13, P = .033; Z = 2.487, P = .013, respectively).

Conclusion

NFL was found to correlate and predict clinical outcome. In addition, it was found to correlate with HT.

Cerebrospinal fluid neurofilament dynamic profiles predict cognitive progression in individuals with de novo Parkinson's disease

Background

Neurofilament light chain protein (NfL) in cerebrospinal fluid (CSF) reflects the severity of neurodegeneration, with its altered concentrations discovered in Parkinson's disease (PD) and Parkinson's disease dementia (PD-D).

Objective

To determine whether CSF NfL, a promising biomarker of neuronal/axonal damage, can be used to monitor cognitive progression in de novo Parkinson's disease and predict future cognitive decline.

Methods

A total of 259 people were recruited in this study, including 85 healthy controls (HC) and 174 neonatal PD patients from the Parkinson's Progression Markers Initiative (PPMI). Multiple linear regression and linear mixed effects models were used to examine the associations of baseline/longitudinal CSF NfL with cognitive decline and other CSF biomarkers. Kaplan-Meier analysis and log-rank test were used to compare the cumulative probability risk of cognition progression during the follow-up. Multivariate cox regression was used to detect cognitive progression in de novo PD.

Results

We found PD patients with mild cognitive impairment (PD-MCI) was higher than with normal cognition (PD-NC) in terms of CSF NfL baseline levels (p = 0.003) and longitudinal increase rate (p = 0.034). Both baseline CSF NfL and its rate of change predicted measurable cognitive decline in de novo PD (MoCA, β = -0.010, p = 0.011; β = -0.0002, p < 0.001, respectively). The predictive effects in de novo PD patients aged >65, male, ill-educated (<13 years) and without carrying Apolipoprotein E ε4 (APOE ε4) seemed to be more obvious and reflected in more domains investigated. We also observed that CSF NfL levels predicted progression in de novo PD patients with different cognitive diagnosis and amyloid status. After an average follow-up of 6.66 ± 2.54 years, higher concentration above the median of baseline CSF NfL was associated with a future high risk of PD with dementia (adjusted HR 2.82, 95% CI: 1.11-7.20, p = 0.030).

Conclusion

Our results indicated that CSF NfL is a promising prognostic predictor of PD, and its concentration and dynamics can monitor the severity and progression of cognitive decline in de novo PD patients.

Biomarker of early neurological deterioration in minor stroke and proximal large vessel occlusion: A pilot study

BACKGROUND

Plasma neurofilament light chain (pNFL) represents one of the scaffolding proteins of central nervous system axonal injury. The aim of this study was to evaluate pNFL as a predictive biomarker for early neurological deterioration (END) in medically managed patients with large vessel occlusion (LVO) and mild presentation (NIHSS < 6).

METHODS

This retrospective study was developed from a prospectively collected stroke database, which was conducted at a large academic comprehensive stroke center in western China. Patients who first presented with acute ischemic stroke (AIS) within 24 h of symptom onset were continuously included. Stroke severity was analyzed at admission using the NIHSS score. The pNFL drawn on admission was analyzed with a novel ultrasensitive single-molecule array.

RESULTS

Thirty-nine consecutive patients were included in the analysis, and 19 (48.72%) patients experienced END. Patients who experienced END had significantly higher pNFL levels (mean, 65.20 vs. 48.28 pg/mL; P < 0.001) and larger infarct volume (mean, 15.46 vs. 9.56 mL; P < 0.001). pNFL was valuable for the prediction of END (OR, 1.170; 95% CI, 1.049-1.306; P = 0.005), even after adjusted for age and sex (OR, 1.178; 95% CI, 1.038-1.323; P = 0.006), blood sampling time, baseline NIHSS, TOAST classification, and infarct volume (OR, 1.168; 95% CI, 1.034-1.320; P = 0.012). The area under the ROC curve was 85.0% (95% CI, 0.731-0.970; P < 0.001). The sensitivity was 73.7%, and the specificity was 80%.

CONCLUSION

END in minor stroke with LVO was distinguishable from those without END following the determination of pNFL in the blood samples within 24 h of onset. The pNFL is a promising biomarker of END in minor stroke with LVO.

CLINICAL TRIAL REGISTRATION

ChiCTR1800020330.

Serum neurofilament light chain levels are correlated with the infarct volume in patients with acute ischemic stroke

Neurofilament light chains (NfLs) are promising biomarkers of neuroaxonal damage in stroke patients. We investigated the correlations between NfL levels and infarct volume, initial stroke severity, and functional outcomes at discharge in patients with acute ischemic stroke. We prospectively included 15 patients with first-ever acute ischemic stroke and 8 age- and sex-matched healthy controls without other neurological disorders. Serum NfL levels were measured using the single-molecule array (Simoa) technique twice within 24 hours of admission (NfL1D) and on the seventh hospital day (NfL7D) in patients with stroke and once in healthy controls. We assessed the infarct volume on diffusion-weighted magnetic resonance imaging using the free software ITK-SNAP. Serum NfL1D levels in stroke patients were significantly higher (28.4 pg/mL; interquartile range [IQR], 43.0) than in healthy controls (14.5 pg/mL; IQR, 3.2; P = .005). Temporal pattern analyses demonstrated that NfL7D levels were increased (114.0 pg/mL; IQR, 109.6) compared to NfL1D levels in all stroke patients (P = .001). There was a strong correlation between NfL7D levels and infarct volume (R = 0.67, P = .007). The difference between NfL1D and NfL7D (NfLdiff levels) was strongly correlated with the infarct volume (R = 0.63; P = .013). However, there was no statistically significant correlation between NfL levels and the initial stroke severity or functional outcomes at discharge. NfL levels in the subacute stage of stroke and the NfL difference between admission and 7th day of hospital were correlated with infarct volume in patients with acute ischemic stroke.

Temporal Patterning of Neurofilament Light as a Blood-Based Biomarker for Stroke: A Systematic Review and Meta-Analysis

Damage to axons is a core feature of ischemic stroke and cerebrovascular disease. The burden of axonal injury is correlated with the acute clinical deficits, the underlying burden of ischemic brain injury, the prognosis of recovery, and may be a meaningful therapeutic target for brain repair. Neurofilament light chain (NfL) has been identified as a blood-based biomarker that reflects neuroaxonal damage resulting from stroke. However, the utility of NfL as a blood-based biomarker in stroke is confounded by studies examining different temporal windows and patient populations. We conducted a systematic review and meta-analysis to verify the utility of blood NfL as a diagnostic, prognostic, and monitoring stroke biomarker. Nineteen studies reporting serum/plasma NfL values for a total of 4,237 distinct patients with stroke were identified. Using available summary data from the 10 studies that employed a common immunoassay platform, we utilized random effects linear mixed modeling and weighted averages to create a phasic model of serum/plasma NfL values in distinct time periods of acute stroke. Weighted averages show that blood NfL levels vary significantly across three distinct temporal epochs of acute (0–7 days), subacute (9–90 days), and chronic (>90 days) stroke with a steep peak in the early subacute period between 14 and 21 days after stroke. Blood NfL values can function as a diagnostic biomarker in distinguishing acute ischemic stroke from transient ischemic attack as well as amongst other cerebrovascular subtypes. Release of NfL into the bloodstream after stroke follows a distinct temporal dynamic that lags several weeks behind stroke onset and reliably associates with a stroke diagnosis despite some variability based on stroke subtype and severity. Identification of these temporal dynamics and the contribution of co- existent cerebrovascular disease states can improve the value of NfL as a stroke biomarker.

Neurofilament light chain concentration in an aging population

BACKGROUND

Neurofilament light chain (NF-L) concentration is recognized to be modified in neurological diseases and traumatic brain injuries, but studies in the normal aging population are lacking. It is, therefore, urgent to identify influencing factors of NF-L concentration in the aging population.

METHOD

We assessed NF-L concentration in sera of a large cohort of 409 community-dwelling adults aged over 65 years. We studied the association between NF-L and various physiological factors but also with self-reported comorbidities or life-style habits.

RESULTS

We showed that NF-L concentration in serum was tightly associated with cystatin C concentration (r = 0.501, p < 0.0001) and consequently, to the estimated glomerular filtration rate (eGFR) (r = - 0.492; p < 0.0001). Additionally, NF-L concentration was dependent on age and body mass index (BMI) but not sex. Among the self-reported comorbidities, subjects who reported neurological disorders, cardiovascular diseases or history of fracture had higher NF-L concentration in univariate analysis, whereas it was only the case for subjects who reported neurological disorders in the multivariate analysis. NF-L concentration was also increased when Mini-Mental State Examination (MMSE) was decreased (≤ 25 points) but not when geriatric depression score (GDS) was increased (> 5 points) in both univariate and multivariate analysis. Finally, we are providing reference ranges by age categories for subjects with or without altered renal function.

CONCLUSION

NF-L concentration in the aging population is not driven by the increasing number of comorbidities or depression. Yet, NF-L blood concentration is dependent on kidney function and NF-L interpretation in patients suffering from renal failure should be taken with caution.

Diagnostic and Prognostic Blood Biomarkers in Transient Ischemic Attack and Minor Ischemic Stroke: An Up-To-Date Narrative Review

INTRODUCTION

Early diagnosis and correct risk stratification in patients with transient ischemic attack (TIA) and minor ischemic stroke (MIS) is crucial for the high rate of subsequent disabling stroke. Although highly improved, diagnosis and prognostication of TIA/MIS patients remain still based on clinical and neuroimaging findings, with some inter-rater variability even among trained neurologists.

OBJECTIVES

To provide an up-to-date overview of diagnostic and prognostic blood biomarkers in TIA and MIS patients.

MATERIAL AND METHODS

We performed a bibliographic search on PubMed database with last access on July 10^th 2021. More than 680 articles were screened and we finally included only primary studies on blood biomarkers.

RESULTS

In a narrative fashion, we discussed about blood biomarkers investigated in TIA/MIS patients, including inflammatory, thrombosis, neuronal injury and cardiac analytes, antibodies and microRNAs. Other soluble molecules have been demonstrated to predict the risk of recurrent cerebrovascular events or treatment response in these patients. A rapid point of care assay, combining the determination of different biomarkers, has been developed to improve triage recognition of acute cerebrovascular accidents.

CONCLUSIONS

The implementation of blood biomarkers in the clinical management of TIA/MIS could ameliorate urgent identification, risk stratification and individual treatment choice. Large prospective and longitudinal studies, adopting standardized sampling and analytic procedures, are needed to clarify blood biomarkers kinetic and their relationship with TIA and minor stroke etiology.

Newly-identified blood biomarkers of neurological damage are correlated with infarct volume in patients with acute ischemic stroke

Our group recently performed a genome-wide informatic analysis that highlighted eight brain-enriched proteins with strong potential to serve as blood biomarkers of neurological injury (GFAP, MBP, β-synuclein, OPALIN, MT-3, SNAP-25, KIF5A, MOBP), including six that have yet to be widely investigated. In this study, our aim was to determine whether the circulating levels of these proteins could be used to approximate the extent of neural tissue damage in ischemic stroke. To address this aim, blood was collected from 43 ischemic stroke patients immediately upon hospital admission. The serum levels of the eight candidate proteins were measured via ELISA, infarct volume was assessed via manual tracing of neuroradiological images, and correlational analysis was performed to examine potential associative relationships. The serum levels of all eight proteins exhibited positive correlations with infarct volume, however the strongest associations were observed in a subset of four proteins known to originate from neurons specifically (MT-3, SNAP-25, KIF5A, β-synuclein). Combining the serum levels of these neuron-originating proteins using principal components analysis produced a single composite value that was more strongly correlated with infarct volume than the levels of any single protein considered in isolation (r = 0.48, p < 0.001). Measures of these proteins could potentially be used to provide a minimally invasive approximation of lesion size when advanced imaging techniques are not available, or when imaging results are inconclusive.

Serum Neurofilament Light: a Potential Diagnostic and Prognostic Biomarker in Obstetric Posterior Reversible Encephalopathy Syndrome

Obstetric posterior reversible encephalopathy syndrome (PRES), caused by preeclampsia (PE) or eclampsia, is a clinical imaging syndrome and a critical maternal complication, with vasogenic edema in white matter as a typical imaging characteristic. Serum neurofilament light (NFL) is a marker of neuroaxonal injury. Therefore, we performed this study to explore the diagnostic and prognostic role of NFL in obstetric PRES. We used stored serum samples and clinical data obtained from 2148 PE or eclampsia patients from the Guangzhou Medical Centre for Critical Pregnant Women from January 2015 to January 2020. The serum NFL concentration was measured by Simoa assay. Patients without complete data and MRI examinations were excluded. All patients were grouped into the PRES and non-PRES groups based on the PRES diagnostic criteria. In total, 222 patients met the inclusion criteria and were grouped into the PRES (n = 123) and non-PRES (n = 99) groups. The NFL level was significantly higher in the PRES group than in the non-PRES group (p < 0.0001). The discriminatory accuracy of diagnostic panels (headaches + NFL, NFL) in receiver operating characteristic curve analysis (area under the curve) was 0.9338 and 0.7664. Importantly, the NFL level was significantly correlated with edema severity (Spearman's correlation, p < 0.0001), and a poorer pregnancy outcome was observed in the PRES group. In conclusion, an increased NFL level can add predictive value for diagnosing obstetric PRES, and its level is associated with both clinical severity and pregnancy outcome, suggesting that NFL could serve as a diagnostic and prognostic biomarker for obstetric PRES.

Serum Neurofilament Dynamics Predicts Cognitive Progression in de novo Parkinson's Disease

BACKGROUND

Neurofilament light (NfL) can reflect the extent of neuron/axon damage, thus providing an opportunity to examine the severity and progression of the diseases with such damage.

OBJECTIVE

Whether serum NfL can be used as an indicator to monitor the cognitive progress of de novo Parkinson's disease (PD) remains unclear.

METHODS

In this research, 144 healthy controls and 301 de novo PD patients from Parkinson's Progression Markers Initiative (PPMI) were recruited. Linear mixed effects models were used to examine the associations of baseline/longitudinal serum NfL with cognitive decline. Cox regression was used to detect cognitive progression in PD participants.

RESULTS

We found PD patients had higher serum NfL than controls at baseline (p = 0.031), and NfL increase was faster in PD group (p < 0.001). Both baseline serum NfL and its rate of change predicted measurable cognitive decline in early PD (MoCA, β= -0.014, p < 0.001; β= -0.002, p < 0.001, respectively). Additionally, we observed that NfL levels were also able to predict progression in different diagnostic groups and Amyloid- PD and Amyloid+PD groups. After an average follow-up of 6.37±1.84 years, the baseline NfL of the third tertile of high concentrations was associated with a future high risk of PD dementia (adjusted HR 6.33, 95% CI 2.62-15.29, p < 0.001).

CONCLUSION

In conclusion, our results indicated that the serum NfL concentration could function as an easily accessible biomarker to monitor the severity and progression of cognitive decline in PD.

The Cytoskeletal Elements MAP2 and NF-L Show Substantial Alterations in Different Stroke Models While Elevated Serum Levels Highlight Especially MAP2 as a Sensitive Biomarker in Stroke Patients

In the setting of ischemic stroke, the neurofilament subunit NF-L and the microtubule-associated protein MAP2 have proven to be exceptionally ischemia-sensitive elements of the neuronal cytoskeleton. Since alterations of the cytoskeleton have been linked to the transition from reversible to irreversible tissue damage, the present study investigates underlying time- and region-specific alterations of NF-L and MAP2 in different animal models of focal cerebral ischemia. Although NF-L is increasingly established as a clinical stroke biomarker, MAP2 serum measurements after stroke are still lacking. Therefore, the present study further compares serum levels of MAP2 with NF-L in stroke patients. In the applied animal models, MAP2-related immunofluorescence intensities were decreased in ischemic areas, whereas the abundance of NF-L degradation products accounted for an increase of NF-L-related immunofluorescence intensity. Accordingly, Western blot analyses of ischemic areas revealed decreased protein levels of both MAP2 and NF-L. The cytoskeletal alterations are further reflected at an ultrastructural level as indicated by a significant reduction of detectable neurofilaments in cortical axons of ischemia-affected areas. Moreover, atomic force microscopy measurements confirmed altered mechanical properties as indicated by a decreased elastic strength in ischemia-affected tissue. In addition to the results from the animal models, stroke patients exhibited significantly elevated serum levels of MAP2, which increased with infarct size, whereas serum levels of NF-L did not differ significantly. Thus, MAP2 appears to be a more sensitive stroke biomarker than NF-L, especially for early neuronal damage. This perspective is strengthened by the results from the animal models, showing MAP2-related alterations at earlier time points compared to NF-L. The profound ischemia-induced alterations further qualify both cytoskeletal elements as promising targets for neuroprotective therapies.

Plasma neurofilament light predicts mortality in patients with stroke

Given the heterogeneity of stroke brain injury, there is a clear need for a biomarker that determines the degree of neuroaxonal injury across stroke types. We evaluated whether blood neurofilament light (NFL) would fulfill this purpose for patients with acute cerebral infarction (ACI; N = 227), aneurysmal subarachnoid hemorrhage (aSAH; N = 58), or nontraumatic intracerebral hemorrhage (ICH; N = 29). We additionally validated our findings in two independent cohorts of patients with ICH (N = 96 and N = 54) given the scarcity of blood biomarker studies for this deadliest stroke type. Compared to healthy individuals (N = 79 and N = 48 for the discovery and validation cohorts, respectively), NFL was higher for all stroke types. NFL associated with radiographic markers of brain tissue damage. It correlated with the extent of early ischemic injury in patients with ACI, hemorrhage severity in patients with aSAH, and intracranial hemorrhage volume in patients with ICH. In all patients, NFL independently correlated with scores from the NIH Stroke Scale, the modified Rankin Scale, and the Mini-Mental State Examination at blood draw, which respectively assess neurological, functional, and cognitive status. Furthermore, higher NFL concentrations independently associated with 3- or 6-month functional disability and higher all-cause mortality. These data support NFL as a uniform method to estimate neuroaxonal injury and forecast mortality regardless of stroke mechanism. As a prognostic biomarker, blood NFL has the potential to assist with planning supportive and rehabilitation services and improving clinical trial efficiency for stroke therapeutics and devices.

Tau, S100B and NSE as Blood Biomarkers in Acute Cerebrovascular Events

BACKGROUND/AIM

We aimed to analyze the diagnostic value of total tau (T-tau), S-100 calcium-binding protein B (S100B) and neuron-specific enolase (NSE) as blood-based biomarkers in acute ischemic stroke (AIS) or transient ischemic attack (TIA), and their correlation with symptom severity, infarct size, etiology and outcome.

PATIENTS AND METHODS

A total of 102 patients with stroke and 35 with TIA were analyzed. Subacute (63.8±50.1 h) plasma T-tau was measured with the single-molecule array (Simoa) method and NSE and S100B were evaluated for comparison. We evaluated biomarkers associations with: (i) diagnosis of AIS or TIA, (ii) cerebral infarction volume in the brain computed tomography, (iii) stroke etiology, (iv) clinical stroke severity and (iv) functional outcome after three months.

RESULTS

T-tau was higher in patients with stroke [1.0 pg/ml (IQR=0.3-2.2)] than with TIA [0.5 pg/ml (IQR=0.2-1.0), p=0.02]. The levels of S100B were also increased in stroke [0.082 μg/l (IQR=0.049-0.157)] patients compared to TIA patients [0.045 μg/l (IQR=0.03-0.073), p<0.001]. However, when the results were adjusted for confounders, significance was lost. Serum levels of NSE among patients with AIS [11.85 μg/l (IQR=9.30-16.14)] compared to those with TIA [10.96 μg/l (IQR=7.98-15.33), p=0.30] were equal. T-tau and S100B concentrations significantly correlated with cerebral infarction volume (r=0.412, p<0.001) and (r=0.597, p<0.001), also after corrections (p<0.001). mRS scores at three-month follow-up correlated with T-tau (r=0.248, p=0.016) and S100B concentrations (r=0.205, p=0.045).

CONCLUSION

For the diagnosis of TIA vs. AIS, blood T-tau and S100B concentrations discriminated only modestly. Additionally, groups were not separable after measuring of T-tau and S100B levels in the blood. T-tau and S100B concentrations correlated with the infarct size, but were not alone predictive for functional outcome at 3 months.

Longitudinal plasma phosphorylated tau 181 tracks disease progression in Alzheimer's disease

To assess plasma phosphorylated tau181 (p-tau181) as a progression biomarker in Alzheimer's disease (AD), we examined longitudinal plasma p-tau181 of 1184 participants (403 cognitively normal (CN), 560 patients with mild cognitive impairment (MCI), and 221 with AD dementia) from Alzheimer's Disease Neuroimaging Initiative (ADNI). The plasma p-tau level was increased at baseline for MCI and AD dementia (mean: CN, 15.4 pg/mL; MCI, 18.4 pg/mL; AD dementia, 23.7 pg/mL; P < 0.001) and increased significantly over time at preclinical (Aβ-positive CN), prodromal (Aβ-positive MCI), and dementia (Aβ-positive dementia) stage of AD. A longitudinal increase of plasma p-tau181 was associated with abnormal cerebrospinal fluid biomarker levels (low Aβ42, high phosphorylated tau, and high total tau, all P < 0.001), amyloid accumulation (P < 0.001) and hypometabolism (P = 0.002) on positron emission tomography, atrophy in structure imaging (small hippocampal (P = 0.030), middle temporal (P = 0.008), and whole brain (P = 0.027) volume, and large ventricular volume (P = 0.008)), and deteriorated cognitive performance (global cognition and memory, language, executive function, and visuospatial function, all P < 0.050) at baseline. Furthermore, longitudinal plasma p-tau181 correlated with concurrent changes of nearly all these AD-related hallmarks and faster increase in plasma p-tau181 correlated with faster worsening cognition in all diagnostic groups. Importantly, most associations remained significant in Aβ-positive group and became non-significant in Aβ-negative group. Longitudinal analyses of plasma p-tau181 suggest its potential as a noninvasive biomarker to track disease progression in AD and to monitor effects of disease-modifying therapeutics in clinical trials.

Blood-Based Biomarkers: A Forgotten Friend of Hyperacute Ischemic Stroke

Ischemic stroke (IS) is the second leading cause of death worldwide. Multimodal neuroimaging techniques that have significantly facilitated the diagnosis of hyperacute IS are not widely used in underdeveloped areas and community hospitals owing to drawbacks such as high cost and lack of trained operators. Moreover, these methods do not have sufficient resolution to detect changes in the brain at the cellular and molecular levels after IS onset. In contrast, blood-based biomarkers can reflect molecular and biochemical alterations in both normal and pathophysiologic processes including angiogenesis, metabolism, inflammation, oxidative stress, coagulation, thrombosis, glial activation, and neuronal and vascular injury, and can thus provide information complementary to findings from routine examinations and neuroimaging that is useful for diagnosis. In this review, we summarize the current state of knowledge on blood-based biomarkers of hyperacute IS including those associated with neuronal injury, glial activation, inflammation and oxidative stress, vascular injury and angiogenesis, coagulation and thrombosis, and metabolism as well as genetic and genomic biomarkers. Meanwhile, the blood sampling time of the biomarkers which are cited and summarized in the review is within 6 h after the onset of IS. Additionally, we also discuss the diagnostic and prognostic value of blood-based biomarkers in stroke patients, and future directions for their clinical application and development.

Tracing Neurological Diseases in the Presymptomatic Phase: Insights From Neurofilament Light Chain

The identification of neurological diseases in their presymptomatic phase will be a fundamental aim in the coming years. This step is necessary both to optimize early diagnostics and to verify the effectiveness of experimental disease modifying drugs in the early stages of diseases. Among the biomarkers that can detect neurological diseases already in their preclinical phase, neurofilament light chain (NfL) has given the most promising results. Recently, its measurement in serum has enabled the identification of neurodegeneration in diseases such as multiple sclerosis (MS) and Alzheimer’s disease (AD) up to 6–10 years before the onset of symptoms. Similar results have been obtained in conditions such as frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), up to 2 years before clinical onset. Study of the longitudinal dynamics of serum NfL has also revealed interesting aspects of the pathophysiology of these diseases in the preclinical phase. This review sought to discuss these very recent findings on serum NfL in the presymptomatic phase of neurological diseases.

A neurologist's perspective on serum neurofilament light in the memory clinic: a prospective implementation study

Background

Neurofilament light in serum (sNfL) is a biomarker for axonal damage with elevated levels in many neurological disorders, including neurodegenerative dementias. Since within-group variation of sNfL is large and concentrations increase with aging, sNfL’s clinical use in memory clinic practice remains to be established. The objective of the current study was to evaluate the clinical use of serum neurofilament light (sNfL), a cross-disease biomarker for axonal damage, in a tertiary memory clinic cohort.

Methods

Six neurologists completed questionnaires regarding the usefulness of sNfL (n = 5–42 questionnaires/neurologist). Patients that visited the Alzheimer Center Amsterdam for the first time between May and October 2019 (n = 109) were prospectively included in this single-center implementation study. SNfL levels were analyzed on Simoa and reported together with normal values in relation to age, as part of routine diagnostic work-up and in addition to cerebrospinal fluid (CSF) biomarker analysis.

Results

SNfL was perceived as useful in 53% (n = 58) of the cases. SNfL was more often perceived as useful in patients < 62 years (29/48, 60%, p = 0.05) and males (41/65, 63%, p < 0.01). Availability of CSF biomarker results at time of result discussion had no influence. We observed non-significant trends for increased perceived usefulness of sNfL for patients with the diagnosis subjective cognitive decline (64%), psychiatric disorder (71%), or uncertain diagnosis (67%). SNfL was mostly helpful to neurologists in confirming or excluding neurodegeneration. Whether sNfL was regarded as useful strongly depended on which neurologist filled out the questionnaire (ranging from 0 to 73% of useful cases/neurologist).

Discussion

Regardless of the availability of CSF biomarker results, sNfL was perceived as a useful tool in more than half of the evaluated cases in a tertiary memory clinic practice. Based on our results, we recommend the analysis of the biomarker sNfL to confirm or exclude neurodegeneration in patients below 62 years old and in males.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-021-00841-4.

Leukocyte TNFR1 and TNFR2 Expression Contributes to the Peripheral Immune Response in Cases with Ischemic Stroke

Tumor necrosis factor receptor 1 and 2 (TNFR1 and TNFR2) have been found in brain parenchyma of stroke patients, and plasma levels are increased in the acute phase of stroke. We evaluated associations between TNFR1 and TNFR2 plasma levels and stroke severity, infarct size, and functional outcome. Furthermore, we examined cellular expression of TNFR1 and TNFR2 on leukocyte subpopulations to explore the origin of the increased receptor levels. Blood samples were taken from 33 acute ischemic stroke patients and 10 healthy controls. TNFR1 and TNFR2 plasma concentrations were measured and correlated against the Scandinavian Stroke Scale at admission, infarct volume, and the modified Rankin Scale score three months after stroke onset. Classical, intermediate, and non-classical monocytes as well as neutrophils were purified, and cellular expression of TNFR1 and TNFR2 was examined using flow cytometry. TNFR1 and TNFR2 plasma levels were both increased after ischemic stroke, but we found no correlation with patient outcome measurements. Compared to healthy controls, ischemic stroke patients had decreased non-classical monocyte and neutrophil populations expressing TNFR1 and increased neutrophils expressing TNFR2, and decreased non-classical populations co-expressing both TNFR1 and TNFR2. This study supports the hypothesis of an acute immunological response orchestrated by the peripheral immune system following an ischemic stroke. However, the origin of the increased TNFR1 and TNFR2 plasma levels could not be clearly linked to peripheral monocytes or neutrophils. Future studies are needed and will help clarify the potential role as treatment target.

Genetic inactivation of RIP1 kinase activity in rats protects against ischemic brain injury

RIP1 kinase-mediated inflammatory and cell death pathways have been implicated in the pathology of acute and chronic disorders of the nervous system. Here, we describe a novel animal model of RIP1 kinase deficiency, generated by knock-in of the kinase-inactivating RIP1(D138N) mutation in rats. Homozygous RIP1 kinase-dead (KD) rats had normal development, reproduction and did not show any gross phenotypes at baseline. However, cells derived from RIP1 KD rats displayed resistance to necroptotic cell death. In addition, RIP1 KD rats were resistant to TNF-induced systemic shock. We studied the utility of RIP1 KD rats for neurological disorders by testing the efficacy of the genetic inactivation in the transient middle cerebral artery occlusion/reperfusion model of brain injury. RIP1 KD rats were protected in this model in a battery of behavioral, imaging, and histopathological endpoints. In addition, RIP1 KD rats had reduced inflammation and accumulation of neuronal injury biomarkers. Unbiased proteomics in the plasma identified additional changes that were ameliorated by RIP1 genetic inactivation. Together these data highlight the utility of the RIP1 KD rats for target validation and biomarker studies for neurological disorders.

Plasma neurofilament light chain is associated with mortality after spontaneous intracerebral hemorrhage

Background Neurofilament light chain (NfL) is a neuron-specific biomarker with prognostic ability in several types of central nervous system injuries. This study investigates if plasma NfL (pNfL) is elevated early after spontaneous intracerebral hemorrhage (ICH) and whether such elevation reflects disease severity and day-30 outcome. Methods pNfL was quantified by single molecule array analysis in 103 reference subjects (RS) and in samples from 37 patients with ICH obtained on admission to hospital and at 24-h follow-up. The primary outcome was day-30 mortality. Clinical status on admission was evaluated by standardized scoring systems. Results Median pNfL among RS was 9.6 (interquartile range [IQR] 6.2) pg/mL. Upon admission, ICH patients had pNfL of 19.8 (IQR 30.7) pg/mL increasing to 35.9 (IQR 44.5) pg/mL at 24 h (all, p < 0.001). On admission, pNfL was higher among ICH non-survivors than survivors (119.2 [IQR 152.6] pg/mL vs. 15.7 [IQR 19.6] pg/mL, p < 0.01) and this difference was observed also on 24 h follow-up (195.1 [IQR 73.9] pg/mL vs. 31.3 [IQR 27.8] pg/mL, p < 0.01). The area under the receiver operating characteristic curve (ROC AUC) for discrimination of day-30 mortality was significant on admission (AUC = 0.83, 95% confidence interval [CI]: 0.56-1.0) and increased on 24-h follow-up (AUC = 0.93, 95% CI: 0.84-1.0). The odds ratio (OR) for death, by each quartile increase in pNfL was significant both on admission (OR = 4.52, 95% CI: 1.32-15.48) and after 24-h follow-up (OR = 9.52, 95% CI: 1.26-71.74). Conclusions PNfL is associated with day-30 mortality after spontaneous ICH when early after the ictus.

Plasma pTau181 predicts cortical brain atrophy in aging and Alzheimer's disease

BACKGROUND

To investigate the association of plasma pTau181, assessed with a new immunoassay, with neurodegeneration of white matter and gray matter cross-sectionally and longitudinally, in aging and Alzheimer's disease.

METHODS

Observational data was obtained from the Alzheimer's Disease Neuroimaging Initiative, in which participants underwent plasma assessment and magnetic resonance imaging. Based on their clinical diagnosis, participants were classified as cognitively unimpaired and cognitively impaired. Linear regressions and linear mixed-effect models were used to test the cross-sectional and longitudinal associations between baseline plasma pTau181 and neurodegeneration using voxel-based morphometry.

RESULTS

We observed a negative correlation at baseline between plasma pTau181 and gray matter volume in cognitively unimpaired individuals. In cognitively impaired individuals, we observed a negative association between plasma pTau181 and both gray and white matter volume. In longitudinal analyses conducted in the cognitively unimpaired group, plasma pTau181 was negatively correlated with gray matter volume, starting 36 months after baseline assessments. Finally, in cognitively impaired individuals, plasma pTau181 concentrations were negatively correlated with both gray and white matter volume as early as 12 months after baseline, and neurodegeneration increased in an incremental manner until 48 months.

CONCLUSIONS

Higher levels of plasma pTau181 correlate with neurodegeneration and predict further brain atrophy in aging and Alzheimer's disease. Plasma pTau181 may be useful in predicting AD-related neurodegeneration, comparable to positron emission tomography or cerebrospinal fluid assessment with high specificity for AD neurodegeneration.

Prediction of Outcome After Endovascular Embolectomy in Anterior Circulation Stroke Using Biomarkers

Stroke is a major public health problem that can cause a long-term disability or death due to brain damage. Serious stroke is frequently caused by a large vessel occlusion in the anterior circulation, which should be treated by endovascular embolectomy if possible. In this study, we investigated the use of the brain damage biomarkers tau, NFL, NSE, GFAp, and S100B to understand the progression of nervous tissue damage and their relationship to outcome in such stroke after endovascular treatment. Blood samples were taken from 90 patients pre-treatment and 2 h, 24 h, 48 h, 72 h and 3 months after endovascular treatment. Stroke-related neurological deficit was estimated using the National Institute of Health Stroke Scale (NIHSS) at admission and at 24 h. Neurological outcome was evaluated at 3 months. After stroke, tau, NFL, GFAp and S100B increased in a time dependent manner, while NSE remained constant over time. At 3 months, tau and GFAp levels were back to normal whereas NFL was still high. Tau, NFL and GFAp correlated well to outcome, as well as to infarct volume and NIHSS at 24 h. The best time for prediction of poor outcome was different for each biomarker. However, the combination of NIHSS at 24 h with either tau, NFL or GFAp at 48 h gave the best prediction. The use of biomarkers in the early setting after endovascular treatment of stroke will lead to a simplified and standardized way to estimate the nervous tissue damage and possibly complement the clinical judgement in foreseeing the need of rehabilitation measures.

Serum neurofilament measurement improves clinical risk scores for outcome prediction after cardiac arrest: results of a prospective study

Background

A recent study found serum neurofilament light chain (NfL) levels to be strongly associated with poor neurological outcome in patients after cardiac arrest. Our aim was to confirm these findings in an independent validation study and to investigate whether NfL improves the prognostic value of two cardiac arrest-specific risk scores.

Methods

This prospective, single-center study included 164 consecutive adult after out-of-hospital cardiac arrest (OHCA) patients upon intensive care unit admission. We calculated two clinical risk scores (OHCA, CAHP) and measured NfL on admission within the first 24 h using the single molecule array NF-light^® assay. The primary endpoint was neurological outcome at hospital discharge assessed with the cerebral performance category (CPC) score.

Results

Poor neurological outcome (CPC > 3) was found in 60% (98/164) of patients, with 55% (91/164) dying within 30 days of hospitalization. Compared to patients with favorable outcome, NfL was 14-times higher in patients with poor neurological outcome (685 ± 1787 vs. 49 ± 111 pg/mL), with an adjusted odds ratio of 3.4 (95% CI 2.1 to 5.6, p < 0.001) and an area under the curve (AUC) of 0.82. Adding NfL to the clinical risk scores significantly improved discrimination of both the OHCA score (from AUC 0.82 to 0.89, p < 0.001) and CAHP score (from AUC 0.89 to 0.92, p < 0.05). Adding NfL to both scores also resulted in significant improvement in reclassification statistics with a Net Reclassification Index (NRI) of 0.58 (p < 0.001) for OHCA and 0.83 (p < 0.001) for CAHP.

Conclusions

Admission NfL was a strong outcome predictor and significantly improved two clinical risk scores regarding prognostication of neurological outcome in patients after cardiac arrest. When confirmed in future outcome studies, admission NfL should be considered as a standard laboratory measures in the evaluation of OHCA patients.

Serum neurofilament light in atrial fibrillation: clinical, neuroimaging and cognitive correlates

Emerging evidence suggests that atrial fibrillation is associated with cognitive dysfunction independently of stroke, but the underlying mechanisms remain unclear. In this cross-sectional analysis from the Swiss-atrial fibrillation Study (NCT02105844), we investigated the association of serum neurofilament light protein, a neuronal injury biomarker, with (i) the CHA₂DS₂-VASc score (congestive heart failure, hypertension, age 65–74 or >75 years, diabetes mellitus, stroke or transient ischaemic attack, vascular disease, sex), clinical and neuroimaging parameters and (ii) cognitive measures in atrial fibrillation patients. We measured neurofilament light in serum using an ultrasensitive single-molecule array assay in a sample of 1379 atrial fibrillation patients (mean age, 72 years; female, 27%). Ischaemic infarcts, small vessel disease markers and normalized brain volume were assessed on brain MRI. Cognitive testing included the Montreal cognitive assessment, trail-making test, semantic verbal fluency and digit symbol substitution test, which were summarized using principal component analysis. Results were analysed using univariable and multivariable linear regression. Neurofilament light was associated with the CHA₂DS₂-VASc score, with an average 19.2% [95% confidence interval (17.2%, 21.3%)] higher neurofilament per unit CHA₂DS₂-VASc increase. This association persisted after adjustment for age and MRI characteristics. In multivariable analyses, clinical parameters associated with neurofilament light were higher age [32.5% (27.2%, 38%) neurofilament increase per 10 years], diabetes mellitus, heart failure and peripheral artery disease [26.8% (16.8%, 37.6%), 15.7% (8.1%, 23.9%) and 19.5% (6.8%, 33.7%) higher neurofilament, respectively]. Mean arterial pressure showed a curvilinear association with neurofilament, with evidence for both an inverse linear and a U-shaped association. MRI characteristics associated with neurofilament were white matter lesion volume and volume of large non-cortical or cortical infarcts [4.3% (1.8%, 6.8%) and 5.5% (2.5%, 8.7%) neurofilament increase per unit increase in log-volume of the respective lesion], as well as normalized brain volume [4.9% (1.7%, 8.1%) higher neurofilament per 100 cm³ smaller brain volume]. Neurofilament light was inversely associated with all cognitive measures in univariable analyses. The effect sizes diminished after adjusting for clinical and MRI variables, but the association with the first principal component was still evident. Our results suggest that in atrial fibrillation patients, neuronal loss measured by serum neurofilament light is associated with age, diabetes mellitus, heart failure, blood pressure and vascular brain lesions, and inversely correlates with normalized brain volume and cognitive function.

Acute Kidney Injury Sensitizes the Brain Vasculature to Ang II (Angiotensin II) Constriction via FGFBP1 (Fibroblast Growth Factor Binding Protein 1)

Acute kidney injury (AKI) causes multiple organ dysfunction. Here, we identify a possible mechanism that can drive brain vessel injury after AKI. We induced 30-minute bilateral renal ischemia-reperfusion injury in C57Bl/6 mice and isolated brain microvessels and macrovessels 24 hours or 1 week later to test their responses to vasoconstrictors and found that after AKI brain vessels were sensitized to Ang II (angiotensin II). Upregulation of FGF2 (fibroblast growth factor 2) and FGFBP1 (FGF binding protein 1) expression in both serum and kidney tissue after AKI suggested a potential contribution to the vascular sensitization. Administration of FGF2 and FGFBP1 proteins to isolated healthy brain vessels mimicked the sensitization to Ang II after AKI. Brain vessels in Fgfbp1-/- AKI mice failed to induce Ang II sensitization. Complementary to this, systemic treatment with the clinically used FGF receptor kinase inhibitor BGJ398 (Infigratinib) reversed the AKI-induced brain vascular sensitization to Ang II. All these findings lead to the conclusion that FGFBP1 is especially necessary for AKI-mediated brain vascular sensitization to Ang II and inhibitors of FGFR pathway may be beneficial in preventing AKI-induced brain vessel injury.

Blood neurofilament light: a critical review of its application to neurologic disease

Neuronal injury is a universal event that occurs in disease processes that affect both the central and peripheral nervous systems. A blood biomarker linked to neuronal injury would provide a critical measure to understand and treat neurologic diseases. Neurofilament light chain (NfL), a cytoskeletal protein expressed only in neurons, has emerged as such a biomarker. With the ability to quantify neuronal damage in blood, NfL is being applied to a wide range of neurologic conditions to investigate and monitor disease including assessment of treatment efficacy. Blood NfL is not specific for one disease and its release can also be induced by physiological processes. Longitudinal studies in multiple sclerosis, traumatic brain injury, and stroke show accumulation of NfL over days followed by elevated levels over months. Therefore, it may be hard to determine with a single measurement when the peak of NfL is reached and when the levels are normalized. Nonetheless, measurement of blood NfL provides a new blood biomarker for neurologic diseases overcoming the invasiveness of CSF sampling that restricted NfL clinical application. In this review, we examine the use of blood NfL as a biologic test for neurologic disease.

CSF Neurofilament Light Chain Elevation Predicts ALS Severity and Progression

Objectives: This study compared neurofilament light chain (NFL) levels in the cerebrospinal fluid (CSF) of patients with sporadic amyotrophic lateral sclerosis (sALS) with levels in patients with other neurological diseases and healthy controls and assessed correlations between NFL levels and clinical indicators of sALS.

Methods: We used enzyme-linked immunosorbent assays to determine the NFL levels in the CSF of 45 patients with sALS, 21 patients with other central nervous system diseases (OCNSDs), 18 with immune-mediated peripheral neuropathy (IMPN), 14 with non-immune-mediated peripheral neuropathy (NIMPN), and 19 healthy controls (HCs).

Results: The median NFL levels in the CSF of the sALS, OCNSD, IMPN, NIMPN, and HC groups were 6510, 5372, 4320, 1477, and 756 pg/mL, respectively. The CSF NFL levels did not differ significantly among the sALS, IMPN, and OCNSD groups, but were significantly higher than those of the NIMPN and HC groups. The NFL CSF levels were significantly higher in the NIMPN group than the HCs. There was a negative correlation between the NFL level and ALS function score (ALSFRS-R), and a positive correlation with the disease progression rate in patients with sALS.

Conclusion: CSF NFL may not be sufficient to distinguish ALS from other central nervous system diseases or peripheral neuropathy, but it predicts ALS severity and progression.

Circulating Neurofilament Light Chain Is Associated With Survival After Pediatric Cardiac Arrest

OBJECTIVES

To characterize neurofilament light levels in children who achieved return of spontaneous circulation following cardiac arrest compared with healthy controls and determine an association between neurofilament light levels and clinical outcomes.

DESIGN

Retrospective cohort study.

SETTING

Academic quaternary PICU.

PATIENTS

Children with banked plasma samples from an acute respiratory distress syndrome biomarker study who achieved return of spontaneous circulation after a cardiac arrest and healthy controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Neurofilament light levels were determined with a highly sensitive single molecule array digital immunoassay. Patients were categorized into survivors and nonsurvivors and into favorable (Pediatric Cerebral Performance Category score of 1-2 or unchanged from baseline) or unfavorable (Pediatric Cerebral Performance Category score of 3-6 or Pediatric Cerebral Performance Category score change ≥1 from baseline). Associations between neurofilament light level and outcomes were determined using Wilcoxon rank-sum test. We enrolled 32 patients with cardiac arrest and 18 healthy controls. Demographics, severity of illness, and baseline Pediatric Cerebral Performance Category scores were similar between survivors and nonsurvivors. Healthy controls had lower median neurofilament light levels than patients after cardiac arrest (5.5 [interquartile range 5.0-8.2] vs 31.0 [12.0-338.6]; p < 0.001). Neurofilament light levels were higher in nonsurvivors than survivors (78.5 [26.2-509.1] vs 12.4 [10.3-28.2]; p = 0.012) and higher in survivors than healthy controls (p = 0.009). The four patients who survived with a favorable outcome had neurofilament light levels that were not different from patients with unfavorable outcomes (21.9 [8.5--35.7] vs 37.2 [15.4-419.1]; p = 0.60) although two of the four patients who survived with favorable outcomes had progressive encephalopathies with both baseline and postcardiac arrest Pediatric Cerebral Performance Category scores of 4.

CONCLUSIONS

Neurofilament light is a blood biomarker of hypoxic-ischemic brain injury and may help predict survival and neurologic outcome after pediatric cardiac arrest. Further study in a larger, dedicated cardiac arrest cohort with serial longitudinal measurements is warranted.

Association Between Longitudinal Plasma Neurofilament Light and Neurodegeneration in Patients With Alzheimer Disease

Importance

Plasma neurofilament light (NfL) has been suggested as a noninvasive biomarker to monitor neurodegeneration in Alzheimer disease (AD), but studies are lacking.

Objective

To examine whether longitudinal plasma NfL levels are associated with other hallmarks of AD.

Design, Setting, and Participants

This North American cohort study used data from 1583 individuals in the multicenter Alzheimer's Disease Neuroimaging Initiative study from September 7, 2005, through June 16, 2016. Patients were eligible for inclusion if they had NfL measurements. Annual plasma NfL samples were collected for up to 11 years and were analyzed in 2018.

Exposures

Clinical diagnosis, Aβ and tau cerebrospinal fluid (CSF) biomarkers, imaging measures (magnetic resonance imaging and fluorodeoxyglucose-positron emission tomography), and tests on cognitive scores.

Main Outcomes and Measures

The primary outcome was the association between baseline exposures (diagnosis, CSF biomarkers, imaging measures, and cognition) and longitudinal plasma NfL levels, analyzed by an ultrasensitive assay. The secondary outcomes were the associations between a multimodal classification scheme with Aβ, tau, and neurodegeneration (ie, the ATN system) and plasma NfL levels and between longitudinal changes in plasma NfL levels and changes in the other measures.

Results

Of the included 1583 participants, 716 (45.2%) were women, and the mean (SD) age was 72.9 (7.1) years; 401 had no cognitive impairment, 855 had mild cognitive impairment, and 327 had AD dementia. The NfL level was increased at baseline in patients with mild cognitive impairment and AD dementia (mean levels: cognitive unimpairment, 32.1 ng/L; mild cognitive impairment, 37.9 ng/L; and AD dementia, 45.9 ng/L; P < .001) and increased in all diagnostic groups, with the greatest increase in patients with AD dementia. A longitudinal increase in NfL level correlated with baseline CSF biomarkers (low Aβ42 [P = .001], high total tau [P = .02], and high phosphorylated tau levels [P = .02]), magnetic resonance imaging measures (small hippocampal volumes [P < .001], thin regional cortices [P = .009], and large ventricular volumes [P = .002]), low fluorodeoxyglucose-positron emission tomography uptake (P = .01), and poor cognitive performance (P < .001) for a global cognitive score. With use of the ATN system, increased baseline NfL levels were seen in A-T+N+ (P < .001), A+T-N+ (P < .001), and A+T+N+ (P < .001), and increased rates of NfL levels were seen in A-T+N- (P = .009), A-T+N+ (P = .02), A+T-N+ (P = .04), and A+T+N+ (P = .002). Faster increase in NfL levels correlated with faster increase in CSF biomarkers of neuronal injury, faster rates of atrophy and hypometabolism, and faster worsening in global cognition (all P < .05 in patients with mild cognitive impairment; associations differed slightly in cognitively unimpaired controls and patients with AD dementia).

Conclusions and Relevance

The findings suggest that plasma NfL can be used as a noninvasive biomarker associated with neurodegeneration in patients with AD and may be useful to monitor effects in trials of disease-modifying drugs.

Acute Neurofilament Light Chain Plasma Levels Correlate With Stroke Severity and Clinical Outcome in Ischemic Stroke Patients

Background: Ischemic stroke causes increased blood–brain barrier permeability and release of markers of axonal damage and inflammation. To investigate diagnostic and prognostic roles of neurofilament light chain (NF-L), we assessed levels of NF-L, S100B, interleukin-6 (IL-6), E-selectin, vascular endothelial growth factor-A (VEGF-A), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) in patients with acute ischemic stroke or transient ischemic attack (TIA) and healthy controls.

Methods: We studied neurofilament (NF) expression in 2 cases of human postmortem ischemic stroke, representing infarcts aged 3- to >7-days. In a prospective study, we measured plasma NF-L and inflammatory markers <8 h of symptom onset and at 72 h in acute ischemic stroke (n = 31), TIA (n = 9), and healthy controls (n = 29). We assessed whether NF-L, S100B, and IL-6 were associated with clinical severity on admission (Scandinavian Stroke Scale, SSS), diagnosis of ischemic stroke vs. TIA, and functional outcome at 3 months (modified Rankin Scale, mRS).

Results: NF expression increased in ischemic neurons and in the infarcted brain parenchyma after stroke. Plasma NF-L levels were higher in stroke patients than in TIA patients and healthy controls, but IL-6 levels were similar. Higher acute NF-L levels were associated with lower SSS scores at admission and higher mRS scores at 3 months. No correlation was observed between NF-L and S100B, NF-L and IL-6, nor between S100B or IL-6 and SSS or mRS. Compared to controls, stroke patients had significantly higher VEGF-A and VCAM-1 at <8 h that remained elevated at 72 h, with significantly higher VEGF-A at <8 h; ICAM-1 was significantly increased at <8 h, while S100B and E-selectin were unchanged.

Conclusions: Plasma NF-L levels, but not IL-6 and S100B, were significant predictors of clinical severity on admission and functional outcome at 3 months. Plasma NF-L is a promising biomarker of functional outcome after ischemic stroke.

Serum neurofilament light chain levels are associated with white matter integrity in autosomal dominant Alzheimer's disease

Neurofilament light chain (NfL) is a protein that is selectively expressed in neurons. Increased levels of NfL measured in either cerebrospinal fluid or blood is thought to be a biomarker of neuronal damage in neurodegenerative diseases. However, there have been limited investigations relating NfL to the concurrent measures of white matter (WM) decline that it should reflect. White matter damage is a common feature of Alzheimer's disease. We hypothesized that serum levels of NfL would associate with WM lesion volume and diffusion tensor imaging (DTI) metrics cross-sectionally in 117 autosomal dominant mutation carriers (MC) compared to 84 non-carrier (NC) familial controls as well as in a subset (N = 41) of MC with longitudinal NfL and MRI data.

In MC, elevated cross-sectional NfL was positively associated with WM hyperintensity lesion volume, mean diffusivity, radial diffusivity, and axial diffusivity and negatively with fractional anisotropy. Greater change in NfL levels in MC was associated with larger changes in fractional anisotropy, mean diffusivity, and radial diffusivity, all indicative of reduced WM integrity. There were no relationships with NfL in NC. Our results demonstrate that blood-based NfL levels reflect WM integrity and supports the view that blood levels of NfL are predictive of WM damage in the brain. This is a critical result in improving the interpretability of NfL as a marker of brain integrity, and for validating this emerging biomarker for future use in clinical and research settings across multiple neurodegenerative diseases.

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Serum NfL levels reflect white matter integrity in autosomal dominant Alzheimer disease.

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Associations between NfL and white matter imaging are present throughout all brain regions.

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Longitudinal white matter alterations are associated with changes in blood NfL.

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Results improve interpretability of NfL as a marker of brain integrity.

Association of serum biomarker neurofilament light concentration with post-stroke depression: A preliminary study

OBJECTIVE

To investigate serum neurofilament light (sNfL) levels in acute ischemic stroke and to assess whether sNfL are related to the severity of disease and a potential prognostic marker of post-stroke depression (PSD) during a 3-month follow-up period.

METHODS

This was a single-center prospective cohort study. The sNfL concentration was measured in baseline samples using the Simoa platform- Single Molecule Array technology. A psychiatrist administered the Structural Clinical Interview for Diagnostic and Statistical Manual IV to all patients and made a diagnosis of PSD 3 months after stroke. The logistic regression was used to examine the association between sNfL and PSD.

RESULTS

In total, 236 ischemic stroke cases were included and finished the follow-up. In the follow-up, 55 patients were defined as PSD, thus the incidence rate was 23.3% (95% confidence intervals [CI]: 17.9%-28.7%). Significant differences were observed between the sNfL levels in patients with PSD (124.8 pg/ml [interquartile range {IQR}: 59.6-159.2]) and in patients without PSD (35.9 pg/ml [IQR: 18.2-60.4]) levels (P < 0.001). After adjusting for age, family history of depression, marital status, National Institutes of Health and Stroke Scale score, C-reactive protein and homocysteine levels, sNfL levels independently predicted the development of post-stroke depression. The crude and adjusted odds ratios [OR] (and 95%CI) of PSD associated with an IQR increase for sNfL were 3.38(2.29, 4.98) and 2.65(1.59, 4.04), respectively. According to receiver operating characteristic curves (ROC) curves, the cut-off value of sNfL to predict PSD was 111.4 pg/ml with an area under the curve (AUC) of 0.84(95% CI, 0.78-0.90) and with the highest sensitivity (61.8%) and specificity (95.4%).

CONCLUSIONS

In this study, elevated level of sNfL is associated with higher risk of 3-month depression in patients with ischemic stroke and makes early diagnoses of depression. The study needs replication to ensure the validity of our preliminary results.

Diagnosis of ischemic stroke using circulating levels of brain-specific proteins measured via high-sensitivity digital ELISA

Limited lower detection ranges associated with traditional immunoassay techniques have prevented the use of brain-specific proteins as blood biomarkers of stroke in the acute phase of care, as these proteins are often only present in circulation at low concentrations. Digital ELISA is a newly developed technique with allows for quantification of proteins in biofluids with up to 1000 times greater sensitivity than conventional ELISA techniques. The purpose of this study was to determine whether the extended lower limits of detection associated with digital ELISA could enable the use of brain-specific proteins as blood biomarkers of ischemic stroke during triage. Blood was sampled from ischemic stroke patients (n = 14) at emergency department admission, as well as from neurologically normal controls matched in terms of risk factors for cardiovascular disease (n = 33). Plasma levels of two brain-specific axonal proteins, neurofilament light chain (NfL) and tau, were measured via digital ELISA, and receiver-operating characteristic analysis was used to determine their ability to discriminate between groups. Plasma levels of NfL and tau were both significantly elevated in stroke patients versus controls, and could respectively discriminate between groups with 92.9% sensitivity / 84.9% specificity, and 85.7% sensitivity / 54.6% specificity. Furthermore, adjustment of measured NfL and Tau levels according to the lower-limits of detection associated with commercially-available conventional ELISA assays resulted in a dramatic and statistically significant decrease in diagnostic performance. Collectively, our results suggest that the increased analytical sensitivity of digital ELISA could enable the use of brain-specific proteins as blood biomarkers of ischemic stroke during triage.

Serum Neurofilament Light Chain as a Predictive Biomarker for Ischemic Stroke Outcome: A Systematic Review and Meta-analysis

BACKGROUND

Stroke is the leading cause of death and long-term disability worldwide. The purpose of the study is to examine the role of serum neurofilament light chain (sNfL) as a predictive biomarker for ischemic stroke outcome.

METHODS

We searched PubMed, Web of Science, and EMBASE for potential studies published in English previous to November 15, 2019. Two independent reviewers screened the search results for studies reporting the correlation between sNfL and stroke outcome in ischemic stroke or transient ischemic attack patients. The Newcastle-Ottawa Scale was adopted to evaluate the quality of the included studies. The pooled odds ratio (OR) of sNfL for stroke functional outcome was calculated with the Comprehensive Meta-Analysis software, version 2. Heterogeneity and publication bias were assessed with the I² test and funnel plot, respectively.

RESULTS

Seven studies met the inclusion criteria. The qualities of the included studies ranged from moderate to high. Despite of the different methods used to measure infarct volume, 5 of the included studies reported similar results about the association between sNfL and infarct volume. Two studies investigating the relationship between sNfL and recurrent ischemic events both reported positive results. In pooled analysis with the adjusted odds ratios (Ors) from multivariate regression models, the meta-analysis reached a pooled adjusted OR = 1.71 [95% CI: 1.17-4.29], which represented that the patients with higher sNfL, compared with lower sNfL patients, had a 1.71 times higher risk of poor functional outcome during follow-up. Both meta-regression and subgroup analysis found that sampling time was an important source of heterogeneity. Based on funnel plot and Egger's test, we did not detect obvious publication bias in our study.

CONCLUSIONS

The sNfL was a promising predictive biomarker for ischemic stroke outcome, and blood sampling time was of great importance in the correlation. The temporal change of sNfL after stroke deserves further exploration in large longitudinal studies and a standardized procedure is warranted.

Neurofilaments in disease: what do we know?

Neurofilaments are proteins selectively expressed in the cytoskeleton of neurons, and increased levels are a marker of damage. Elevated neurofilament levels can serve as a marker of ongoing disease activity as well as a tool to measure response to therapeutic intervention. The potential utility of neurofilaments has drastically increased as recent advances have made it possible to measure levels in both the cerebrospinal fluid and blood. There is mounting evidence that neurofilament light chain (NfL) and phosphorylated neurofilament heavy chain (NfH) are abnormal in a host of neurodegenerative diseases. In this review we examine how both of these proteins behave across diseases and what we know about how these biomarkers relate to in vivo white matter pathology and each other.