Serum Neurofilament Light concentrations are not associated with renal function in secondary progressive multiple sclerosis

Blood-based biomarkers can be economic and easily accessible tools for monitoring and predicting disease activity in multiple sclerosis. The objective of this study was to determine the predictive value of a multivariate proteomic assay for concurrent and future microstructural/axonal brain pathology in a longitudinal study of a heterogeneous group of people with multiple sclerosis. A proteomic analysis was obtained on serum samples from 202 people with multiple sclerosis (148 relapsing-remitting and 54 progressive) at baseline and 5-year follow-up. The concentration of 21 proteins related to multiple pathways of multiple sclerosis pathophysiology was derived using Proximity Extension Assay on the Olink platform. Patients were imaged on the same 3T MRI scanner at both timepoints. Тhe rate of whole brain, white matter and grey matter atrophy over the 5-year follow-up was determined using the multi-timepoint Structural Image Evaluation, using Normalisation, of Atrophy algorithms. Lesion burden measures were also assessed. The severity of microstructural axonal brain pathology was quantified using diffusion tensor imaging. Fractional anisotropy and mean diffusivity of normal-appearing brain tissue, normal-appearing white matter, grey matter, T2 and T1 lesions were calculated. Age, sex and body mass index-adjusted step-wise regression models were used. Glial fibrillary acidic protein was the most common and highest-ranked proteomic biomarker associated with greater concurrent microstructural central nervous system alterations (P < 0.001). The rate of whole brain atrophy was associated with baseline levels of glial fibrillary acidic protein, protogenin precursor, neurofilament light chain and myelin oligodendrocyte (P < 0.009), whereas grey matter atrophy was associated with higher baseline neurofilament light chain, higher osteopontin and lower protogenin precursor levels (P < 0.016). Higher baseline glial fibrillary acidic protein level was a significant predictor of future severity of the microstructural CNS alterations as measured by normal-appearing brain tissue fractional anisotropy and mean diffusivity (standardized β = −0.397/0.327, P < 0.001), normal-appearing white matter fractional anisotropy (standardized β = −0.466, P < 0.0012), grey matter mean diffusivity (standardized β = 0.346, P < 0.011) and T2 lesion mean diffusivity (standardized β = 0.416, P < 0.001) at the 5-year follow-up. Serum levels of myelin-oligodendrocyte glycoprotein, neurofilament light chain, contactin-2 and osteopontin proteins were additionally and independently associated with worse concomitant and future axonal pathology. Higher glial fibrillary acidic protein levels were associated with future disability progression (Exp(B) = 8.65, P = 0.004). Multiple proteomic biomarkers are independently associated with greater severity of axonal brain pathology as measured by diffusion tensor imaging in multiple sclerosis. Baseline serum glial fibrillary acidic protein levels can predict future disability progression.

To determine rates of cerebral atrophy in individuals with symptoms of memory loss but no objective cognitive impairment (SNCI) and their association with future cognitive decline. Thirty-two SNCI subjects, 16 with mild cognitive impairment (MCI) and 27 control subjects had clinical assessment and magnetic resonance imaging at baseline and 1 year later. Rates of whole brain atrophy (WBA), hippocampal atrophy (HA) and ventricular enlargement (VE) were measured. Our outcome was clinical diagnosis at 2 years after entry into the study. The MCI group had greater rates of WBA, HA and VE than both controls and SNCI subjects. As a group SNCI subjects did not have significantly greater rates of atrophy than the controls. However, SNCI subjects who progressed to MCI or dementia had increased rates of atrophy compared with those who remained stable. Individuals with memory complaints but no objective memory deficits, who progress to MCI or dementia, have increased rates of cerebral atrophy.

Introduction:Serum neurofilament light (NfL) is an emerging biomarker of traumatic brain injury (TBI). However, the effect of peripheral injuries such as long bone fracture and skeletal muscle injury on serum NfL levels is unknown. Therefore, the aim of this study was to determine whether serum NfL levels can be used as a biomarker of TBI in the presence of concomitant peripheral injuries.Methods:Rats were randomly assigned to one of four injury groups: polytrauma (muscle crush + fracture + TBI; n = 11); peripheral injuries (muscle crush + fracture + sham-TBI; n = 12); TBI-only (sham-muscle crush + sham-fracture + TBI; n = 13); and triple-sham (n = 7). At 2-days post-injury, serum levels of NfL were quantified using a Simoa HD-X Analyzer.Results:Compared to triple-sham rats, serum NfL concentrations were higher in rats with peripheral injuries-only, TBI-only, and polytrauma. When compared to peripheral injury-only rats, serum NfL levels were higher in TBI-only and polytrauma rats. No differences were found between TBI-only and polytrauma rats.Conclusion:Serum NfL levels did not differ between TBI-only and polytrauma rats, indicating that significant peripheral injuries did not affect the sensitivity and specificity of serum NfL as a biomarker of moderate TBI. However, the finding of elevated serum NfL levels in rats with peripheral injuries in the absence of a TBI suggests that the presence of such injuries may limit the utility of NfL as a biomarker of less severe TBI (eg, concussion).

We read with great interest the study by Aamodt and colleagues reporting that plasma neurofilament light (NfL) chain levels are associated with UPDRS III (Unified Parkinson's Disease Rating Scale, Part III) score but not the Mattis Dementia Rating Scale (DRS-2), whereas plasma NfL predicted cognitive decline (DRS-2 change) but not motor worsening (UPDRS III ≥5 points).1 Interestingly, these findings are in line with our results that serum NfL was associated with UPDRS III but not Montreal Cognitive Assessment (MoCA) score, whereas serum NfL predicted cognitive decline (decrease in MoCA score >2 points) but not motor worsening (increase in UPDRS III >4 points) in the Biomarkers in Parkinson's Disease (MARK-PD) study.2 Numerous studies have shown that blood NfL predicts cognitive decline in patients with Parkinson's disease, but cutoff values determined by receiver operating characteristic (ROC) analysis revealed very different results.1-3 Given that serum NfL levels increase by 3.35% per year in PD patients and double in individuals above 70 years compared with those below 50 years in the normal population, age is the most important covariate of NfL variability.4, 5 Consequently, we hypothesize that age-adjusted NfL percentiles might reveal more consistent results among cohort studies compared with absolute NfL values for the prediction of disease progression in PD patients. Therefore, we evaluated if the plasma NfL cutoff value of 14.6 pg/mL determined by Aamodt and colleagues also predicts cognitive decline in the Mark-PD study.6 Furthermore, we analyzed if age-adjusted serum NfL above the 95th percentile predicts cognitive decline in MARK-PD. In MARK-PD, serum NfL and cognitive outcome (initial and follow-up MoCA scores) were available for 106 patients with PD (age: 64.6 ± 8.8 years, men: 60.4%, disease duration: 12 [7.5, 15.5] years, follow-up: 512 [365, 680] days). During follow-up, we registered 21 patients with cognitive decline (decrease in MoCA score >2 points). In a Kaplan–Meier analysis, we observed no association between serum NfL levels and faster cognitive decline using a cutoff value of 14.6 pgl/mL (log-rank test: P = 0.322) (Fig. 1A). However, patients with NfL levels above the age-adjusted 95th percentile revealed a significantly faster cognitive decline (P = 0.026) than those below (Fig. 1B). This difference remained significant after further adjustment for age, sex, disease duration, and initial MoCA score (P = 0.017) (Fig. 1C). In summary, both studies using different cognitive scales (ie, DRS-2 and MoCA) show that increased NfL levels predict cognitive decline in PD patients. We suggest that NfL levels above the age-adjusted 95th percentile are independently associated with cognitive decline. We propose that age-adjusted NfL cutoffs might reveal more consistent results across different cohort studies and therefore facilitate the establishment of NfL as a clinically useful blood-based biomarker in patients with PD. The data that support the findings of this study are available from the corresponding author upon reasonable request.

To improve outcome prediction following subarachnoid haemorrhage (SAH), we sought a biomarker integrating early brain injury and multiple secondary pathological processes in a prospective study of 42 non-traumatic SAH patients and 19 control individuals. Neurofilament light (NF-L) was elevated in CSF and serum following SAH. CSF and serum NF-L on Days 1–3 post-SAH strongly predicted modified Rankin score at 6 months, independent of World Federation of Neurosurgical Societies (WFNS) score. NF-L from Day 4 onwards also had a profound impact on outcome. To link NF-L to a SAH-specific pathological process, we investigated NF-L’s relationship with extracellular haemoglobin. Most CSF haemoglobin was not complexed with haptoglobin, yet was able to be bound by exogenous haptoglobin i.e. haemoglobin was scavengeable. CSF scavengeable haemoglobin was strongly predictive of subsequent CSF NF-L. Next, we investigated NF-L efflux from the brain after SAH. Serum and CSF NF-L correlated positively. The serum/CSF NF-L ratio was lower in SAH versus control subjects, in keeping with glymphatic efflux dysfunction after SAH. CSF/serum albumin ratio was increased following SAH versus controls. The serum/CSF NF-L ratio correlated negatively with the CSF/serum albumin ratio, indicating that transfer of the two proteins across the blood–brain interface is dissociated. In summary, NF-L is a strong predictive marker for SAH clinical outcome, adding value to the WFNS score, and is a promising surrogate end point in clinical trials.

Impaired cognition is a major predisposing factor for postoperative delirium, but it is not systematically assessed. Anesthesia and surgery may cause postoperative delirium by affecting brain integrity. Neurofilament light in serum reflects axonal injury. Studies evaluating the perioperative course of neurofilament light in cardiac surgery have shown conflicting results. The authors hypothesized that postoperative serum neurofilament light values would be higher in delirious patients, and that baseline concentrations would be correlated with patients' cognitive status and would identify patients at risk of postoperative delirium. This preplanned secondary analysis included 220 patients undergoing elective cardiac surgery with cardiopulmonary bypass. A preoperative cognitive z score was calculated after a neuropsychological evaluation. Quantification of serum neurofilament light was performed by the Simoa (Quanterix, USA) technique before anesthesia, 2 h after surgery, on postoperative days 1, 2, and 5. Postoperative delirium was assessed using the Confusion Assessment Method for Intensive Care Unit, the Confusion Assessment Method, and a chart review. A total of 65 of 220 (29.5%) patients developed postoperative delirium. Delirious patients were older (median [25th percentile, 75th percentile], 74 [64, 79] vs. 67 [59, 74] yr; P < 0.001) and had lower cognitive z scores (-0.52 ± 1.14 vs. 0.21 ± 0.84; P < 0.001). Postoperative neurofilament light concentrations increased in all patients up to day 5, but did not predict delirium when preoperative concentrations were considered. Baseline neurofilament light values were significantly higher in patients who experienced delirium. They were influenced by age, cognitive z score, renal function, and history of diabetes mellitus. Baselines values were significantly correlated with cognitive z scores (r, 0.49; P < 0.001) and were independently associated with delirium whenever the patient's cognitive status was not considered (hazard ratio, 3.34 [95% CI, 1.07 to 10.4]). Cardiac surgery is associated with axonal injury, because neurofilament light concentrations increased postoperatively in all patients. However, only baseline neurofilament light values predicted postoperative delirium. Baseline concentrations were correlated with poorer cognitive scores, and they independently predicted postoperative delirium whenever patient's cognitive status was undetermined.

Progressive supranuclear palsy (PSP) and multiple system (MSA) atrophy are associated with progressive brain atrophy. Serial MRI can be applied in order to measure this change in brain volume and to calculate atrophy rates. We evaluated MRI derived whole brain and regional atrophy rates as potential markers of progression in PSP and the Parkinsonian variant of multiple system atrophy (MSA-P). 17 patients with PSP, 9 with MSA-P and 18 healthy controls underwent two MRI brain scans. MRI scans were registered, and brain and regional atrophy rates (midbrain, pons, cerebellum, third and lateral ventricles) measured. Sample sizes required to detect the effect of a proposed disease-modifying treatment were estimated. The effect of scan interval on the variance of the atrophy rates and sample size was assessed. Based on the calculated yearly rates of atrophy, for a drug effect equivalent to a 30% reduction in atrophy, fewer PSP subjects are required in each treatment arm when using midbrain rather than whole brain atrophy rates (183 cf. 499). Fewer MSA-P subjects are required, using pontine/cerebellar, rather than whole brain atrophy rates (164/129 cf. 794). A reduction in the variance of measured atrophy rates was observed with a longer scan interval. Regional rather than whole brain atrophy rates calculated from volumetric serial MRI brain scans in PSP and MSA-P provide a more practical and powerful means of monitoring disease progression in clinical trials.

Introduction: While the morbidity and mortality attributable to gliomas and brain metastases is significant, there are currently no approved biomarkers for detecting and monitoring intracranial disease and imaging remains the primary modality. Blood levels of the neurofilament light (NfL) and tau, as well as glial fibrillary acidic protein (GFAp) show promise as biomarkers for brain injury. We therefore hypothesized that these biomarkers would correlate with CNS activity of gliomas and brain metastases. Methods: Serum concentrtaions of NfL, tau and GFAp were measured using the ultrasensitive single molecule array (Simoa) technology (Quanterix, Lexington, MA). Levels of the three proteins were then correlated with status of gliomas and brain metastases in the patients. Statistical analysis was performed using GraphPad Prism7 and all p-values were 2-tailed with an accepted 2-sided alpha level of 0.05 as statistically significant. Results: 36 patients were enrolled with varying malignancies. Both serum NfL and GFAp levels were significantly associated with the state of intracranial disease (ANOVA psNfL= 0.0307; ANOVA pGFAp=0.0348). In contrast, serum tau levels were discordant with brain involvement with cancer (ANOVA pTau= 0.1453). Conclusion: Serum NfL and GFAp both apparently vary closely with presence and activity of gliomas and brain metastases. Our studies are among the first to identify possible candidate serum biomarkers for screening and monitoring cancer patients for CNS involvement with malignancy. Further studies in larger populations are needed to expand these findings. Citation Format: Jason Porter, Adriana Hepner, Manjari Pandey, Philippe Prouet, Felicia Hare, Syed S. Nasir, Madison Boles, Henrik Zetterberg, Kaj Blennow, Michael Martin. Serum neurofilament light (NfL), glial fibrillary acidic protein (GFAp) and tau protein are possible serum biomarkers for activity of brain metastases and gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1352.

BackgroundCognitive resilience refers to processes involved in coping with effects of brain pathology on cognition. Factors contributing to cognitive resilience against brain atrophy are unclear, as there have been few longitudinal studies investigating this. Therefore we aimed to identify factors explaining the discrepancy between brain atrophy and longitudinal cognitive decline. One proposed method of investigating cognitive resilience is a residual approach, which suggests using the variance in cognition not explained by a specified predictor as a measure of resilience.MethodCognitively unimpaired subjects (n=406) from The Swedish BioFINDER Study with magnetic resonance imaging (MRI) and cognitive test results from at least two time points were included. Using FreeSurfer, global cortical thickness was calculated. A cognitive composite score was calculated from Mini Mental State Examination, Alzheimer´s Disease Assessment Scale – Cognitive Subscale delayed word recall, Trail Making Test B, and Animal fluency. For each subject, the beta coefficients for change in cortical thickness and change in cognition over time were calculated. Linear regression was performed between the two beta coefficients, and the residuals were used as a measure of cognitive resilience. Associations were calculated between this resilience measure and baseline demographics, biomarkers of amyloid (cerebrospinal fluid (CSF) β‐amyloid (Aβ) 42/40 ratio), tau (CSF phosphorylated tau (p‐tau)), and vascular (MRI white matter lesion (WML) volume) pathology as well as neurodegeneration (CSF neurofilament light (NfL)). For dichotomous variables (sex and pathologic Aβ42/40 ratio) independent samples t‐tests, and for continuous variables (all other variables) Pearson correlations, were performed.ResultIn univariate models, lower age at baseline, female sex, higher cortical thickness and better cognitive results at baseline were associated with higher cognitive resilience against cortical atrophy, while education was not. Further, pathological Aβ42/40 ratio and higher levels of p‐tau, NfL, and WMLs at baseline were negatively associated with cognitive resilience in univariate analyses. In a multivariable linear regression model, lower baseline cortical thickness, a pathological Aβ42/40 ratio, and higher NfL were significantly associated with worse cognitive resilience (Figure 1, Table 1).ConclusionMarkers of Alzheimer´s disease pathology and neurodegeneration are associated with worse than expected cognitive decline at a given rate of brain atrophy.

Background: Sensitive and specific biomarkers for use in progressive multiple sclerosis (MS) have not been established. We investigate neurofilament light (NfL) as a treatment response biomarker in progressive MS. Objective: To evaluate whether ibudilast 100 mg/day alters serum and cerebrospinal fluid (CSF) levels of NfL in progressive MS. Methods: In a protocol-defined exploratory analysis from a 2-year, phase 2 clinical trial of ibudilast in progressive MS (NCT01982942), serum samples were collected from 239 subjects and a subset contributed CSF and assayed using single-molecule assay (SIMOA) immunoassay. A mixed model for repeated measurements yielded log(NfL) as the response variable. Results: The geometric mean baseline serum NfL was 31.9 and 28.8 pg/mL in placebo and ibudilast groups, respectively. The geometric mean baseline CSF NfL was 1150.8 and 1290.3 pg/mL in placebo and ibudilast groups, respectively. Serum and CSF NfL correlations were r = 0.52 and r = 0.78 at weeks 48 and 96, respectively. Over 96 weeks, there was no between-group difference in NfL in either serum (p = 0.76) or CSF (p = 0.46). After controlling for factors that may affect NfL, no effect of ibudilast on NfL in either serum or CSF was observed. Conclusion: Ibudilast treatment was not associated with a change in either serum or CSF NfL.

Temporal profile and utility of serum neurofilament light in a rat model of mild traumatic brain injury

Structured SummaryBackground.With increasing recognition of the value of incorporating prognostic markers into amyotrophic lateral sclerosis (ALS) trial design and analysis plans, there is a pressing need to understand which among the prevailing clinical and biochemical markers have real value, and how they can be optimally used.Methods.A subset of patients with ALS recruited through the multi-center Phenotype-Genotype-Biomarker study (clinicaltrials.gov: NCT02327845) was identified as “trial-like” based on meeting common trial eligibility criteria. Clinical phenotyping was performed by evaluators trained in relevant assessments. Serum neurofilament light (NfL) and phosphorylated neurofilament heavy (pNfH), urinary p75ECD, plasma microRNA-181, and an array of biochemical and clinical measures were evaluated for their prognostic value. Associations with functional progression were estimated by random-slopes mixed models of ALS functional rating scale-revised (ALSFRS-R) score. Associations with survival were estimated by log-rank test and Cox proportional hazards regression. Potential sample size savings from adjusting for given biomarkers in a hypothetical trial were estimated.Findings.Baseline serum NfL is a powerful prognostic biomarker, predicting survival and ALSFRS-R rate of decline. Serum NfL <40pg/ml and >100pg/ml correspond to future ALSFRS-R slopes of ~0.5 and 1.5 points/month, respectively. Serum NfL also adds value to the best available clinical predictors, encapsulated by the European Network to Cure ALS (ENCALS) predictor score. In models of functional decline, the addition of NfL yields ~25% sample size saving above those achieved by inclusion of either clinical predictors or ENCALS score alone. The prognostic value of serum pNfH, urinary p75ECD, and plasma miR-181ab is more limited.Interpretation.Among the multitude of biomarkers considered, only blood NfL adds value to the ENCALS prediction model and should be incorporated into analysis plans for all ongoing and future ALS trials. Defined thresholds of NfL might also be used in trial design, for enrichment or stratified randomisation, to improve trial efficiency.Funding.NIH (U01-NS107027, U54-NS092091). ALSA (16-TACL-242).

Objective:To determine whether lipoic acid (LA), an endogenously produced antioxidant, slowed the whole-brain atrophy rate and was safe in secondary progressive MS (SPMS).Methods:Patients with SPMS aged 40–70 years enrolled in a single center, 2-year, double-blind, randomized trial of daily oral 1,200 mg LA vs placebo. Primary outcome was change in annualized percent change brain volume (PCBV). Secondary outcomes were changes in rates of atrophy of segmented brain, spinal cord, and retinal substructures, disability, quality of life, and safety. Intention-to-treat analysis used linear mixed models.Results:Participation occurred between May 2, 2011, and August 14, 2015. Study arms of LA (n = 27) and placebo (n = 24) were matched with mean age of 58.5 (SD 5.9) years, 61% women, mean disease duration of 29.6 (SD 9.5) years, and median Expanded Disability Status Score of 6.0 (interquartile range 1.75). After 2 years, the annualized PCBV was significantly less in the LA arm compared with placebo (−0.21 [standard error of the coefficient estimate (SEE) 0.14] vs −0.65 [SEE 0.10], 95% confidence interval [CI] 0.157–0.727, p = 0.002). Improved Timed 25-Foot Walk was almost but not significantly better in the LA than in the control group (−0.535 [SEE 0.358] vs 0.137 [SEE 0.247], 95% CI −1.37 to 0.03, p = 0.06). Significantly more gastrointestinal upset and fewer falls occurred in LA patients. Unexpected renal failure (n = 1) and glomerulonephritis (n = 1) occurred in the LA cohort. Compliance, measured by pill counts, was 87%.Conclusions:LA demonstrated a 68% reduction in annualized PCBV and suggested a clinical benefit in SPMS while maintaining favorable safety, tolerability, and compliance over 2 years.ClinicalTrials.gov identifier:NCT01188811.Classification of evidence:This study provides Class I evidence that for patients with SPMS, LA reduces the rate of brain atrophy.

In “Serum neurofilament light is sensitive to active cerebral small vessel disease,” the authors highlighted neurofilament light (NfL)'s role as a new biomarker for active cerebral small vessel disease (CSVD). Drs. Schreiber et al. report their own data in patients with CSVD and microhemorrhages, which showed significantly higher concentrations of CSF NfL in patients with CSVD than in controls. Their findings support that NfL may be a biomarker for CSVD burden. In “Serum neurofilament light is sensitive to active cerebral small vessel disease,” the authors highlighted neurofilament light (NfL)'s role as a new biomarker for active cerebral small vessel disease (CSVD). Drs. Schreiber et al. report their own data in patients with CSVD and microhemorrhages, which showed significantly higher concentrations of CSF NfL in patients with CSVD than in controls.

The aim of this study was to assess whether the use of accelerated MRI scans in place of non-accelerated scans influenced brain volume and atrophy rate measures in controls and subjects with mild cognitive impairment and Alzheimer’s disease. We used data from 861 subjects at baseline, 573 subjects at 6 months and 384 subjects at 12 months from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). We calculated whole-brain, ventricular and hippocampal atrophy rates using the k-means boundary shift integral (BSI). Scan quality was visually assessed and the proportion of good quality accelerated and non-accelerated scans compared. We also compared MMSE scores, vascular burden and age between subjects with poor quality scans with those with good quality scans. Finally, we estimated sample size requirements for a hypothetical clinical trial when using atrophy rates from accelerated scans and non-accelerated scans. No significant differences in whole-brain, ventricular and hippocampal volumes and atrophy rates were found between accelerated and non-accelerated scans. Twice as many non-accelerated scan pairs suffered from at least some motion artefacts compared with accelerated scan pairs (p ≤ 0.001), which may influence the BSI. Subjects whose accelerated scans had significant motion had a higher mean vascular burden and age (p ≤ 0.05) whilst subjects whose non-accelerated scans had significant motion had poorer MMSE scores (p ≤ 0.05). No difference in estimated sample size requirements was found when using accelerated vs. non-accelerated scans. Accelerated scans reduce scan time and are better tolerated. Therefore it may be advantageous to use accelerated over non-accelerated scans in clinical trials that use ADNI-type protocols, especially in more cognitively impaired subjects.