Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system of unknown etiology. We tested the hypothesis that MS is caused by Epstein-Barr virus (EBV) in a cohort comprising more than 10 million young adults on active duty in the US military, 955 of whom were diagnosed with MS during their period of service. Risk of MS increased 32-fold after infection with EBV but was not increased after infection with other viruses, including the similarly transmitted cytomegalovirus. Serum levels of neurofilament light chain, a biomarker of neuroaxonal degeneration, increased only after EBV seroconversion. These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS.

JOINT CONTRIBUTION OF MARKERS OF NEURODEGENERATION AND HYPERCHOLESTEROLEMIA TO DEMENTIA RISK

Background The examination of markers of neurodegeneration (glial fibrillary acidic protein; GFAP, neurofilament light chain; NfL, phosphorylated tau181; p-tau181) among individuals with high comorbidity of neurodegenerative and cerebrovascular disease and their interplay with vascular risk factors, particularly high cholesterol levels, might contribute to explaining the link between body and brain. The aim of this study was to assess whether the association of GFAP, NfL, and p-tau181 with dementia risk varies depending on levels of total cholesterol (TC) and APOE ε4 genotype. Methods Nested case-control study embedded within a population-based cohort and including 768 older adults (261 dementia cases and 508 randomly selected controls) followed for up to 17 years with regard to clinical diagnosis of various age-related diseases. GFAP, NfL, and p-tau181 were measured in baseline blood samples using the Single-Molecule Array (Simoa) Technology (Quanterix, USA) and categorized into high (quartile 4) versus low (quartiles 1-3). Logistic regression analyses and spline regression models for dose-response analyses were used. ROC curves by cholesterol levels were also calculated. Results The risk of a dementia diagnosis was significantly increased between participants with high vs. low levels of GFAP and NfL and the risk substantially varied by TC levels. For GFAP and NfL the ORs of a dementia diagnosis were 5.10 (2.45-10.60) and 2.96 (1.43-6.14) in participants with high and 2.44 (1.47-4.07) and 1.15 (0.69-1.92) in those with low TC. APOE ε4 genotype further modified the strength of the associations with different patterns, depending on specific marker and type of dementia. No significant association was seen with p-tau181. Conclusions These results suggest that in the general population blood GFAP and NfL are better predictors of dementia than p-tau181 and that their associations with dementia risk are highly amplified by hypercholesterolemia, also depending on APOE ε4 genotype.

Interactions between weight loss and plasma neurodegenerative markers for determining cognitive decline among community-dwelling older adults

This study aimed to investigate the interaction between weight loss (WL) and plasma amyloid-β42/40 (Aβ42/40), neurofilament light chain (NfL), progranulin, and their association with cognitive decline over time among older adults. This 5-year observational approach included 470 participants from the Multidomain Alzheimer Preventive Trial (MAPT), mean age 76.8y (SD=4.5), 59.4% women. WL was defined as ≥5% decrease over the first year. Biomarkers were measured at 12 months. Cognitive function was assessed yearly from 12 months onwards by Mini-Mental State Examination (MMSE); Clinical Dementia Rating sum of boxes (CDR-SB); a composite score based on Category Naming Test, Digit Symbol Substitution Test, ten MMSE orientation items (MMSEO) and Free and total recall of the Free and Cued Selective Reminding test; and these tests individually. Twenty-seven participants (5.7%) presented WL. In adjusted analyses, combined WL+lower Aβ42/40 (≤0.103, lowest quartile) was related with more pronounced 4-year cognitive decline according to CDR-SB (p<0.0001) and MMSEO (p=0.021), compared to non-WL+higher Aβ42/40. WL+higher NfL (>94.55pg/mL, highest quartile) or progranulin (>38.4ng/mL, three higher quartiles) were related with higher cognitive decline according to CDR-SB, MMSE, MMSEO and composite score (all p<0.03), compared to non-WL+lower NfL or higher progranulin. Regrouping progranulin quartiles (Q1-Q3 vs. Q4) revealed higher cognitive decline among the WL+lower progranulin group compared to non-WL+lower progranulin. In conclusion, 1-year WL was associated with subsequent higher 4-year cognitive decline among older adults presenting low Aβ42/40 or high NfL. Future studies combining plasma biomarker assessments and body weight surveillance may be useful for identifying people at risk of cognitive impairment.

Cerebrospinal fluid neurofilament light chain differentiates behavioural variant frontotemporal dementia progressors from phenocopy non-progressors

Background: Distinguishing behavioural variant frontotemporal dementia (bvFTD) from non-neurodegenerative non-progressor, phenocopy mimics of frontal lobe dysfunction, can be one of the most challenging clinical dilemmas. A biomarker of neuronal injury, neurofilament light chain (NfL), could reduce misdiagnosis and delay. Methods: Cerebrospinal fluid (CSF) NfL, amyloid beta 1-42 (AB42), total and phosphorylated tau (T-tau, P-tau) levels were examined in patients with an initial diagnosis of bvFTD. Based on follow up information, patients were categorised as Progressors. Non-Progressors were subtyped in to Phenocopy Non-Progressors (non-neurological/neurodegenerative final diagnosis), and Static Non-Progressors (static deficits, not fully explained by non-neurological/neurodegenerative causes). Results: Forty-three patients were included: 20 Progressors, 23 Non-Progressors (15 Phenocopy, 8 Static), 20 controls. NfL concentrations were lower in Non-Progressors (Non-Progressors Mean, M=554pg/mL, 95%CI:[461, 675], Phenocopy Non-Progressors M=459pg/mL, 95%CI:[385, 539], Static Non-Progressors M=730pg/mL, 95%CI:[516, 940]), compared to bvFTD Progressors (M=2397pg/mL, 95%CI:[1607, 3332]). NfL distinguished Progressors from Non-Progressors with the highest accuracy (area under the curve 0.92, 90%/87% sensitivity/specificity, 86%/91% positive/negative predictive value, 88% accuracy). Static Non-Progressors tended to have higher T-tau and P-tau levels compared to Phenocopy Non-Progressors. Conclusion: This study demonstrated strong diagnostic utility of CSF NfL to distinguish bvFTD from phenocopy non-progressor variants, at baseline, with high accuracy, in a real-world clinical setting. This has important clinical implications, to improve outcomes for patients and clinicians facing this challenging clinical dilemma, as well as for healthcare services, and clinical trials. Further research is required to investigate heterogeneity within the non-progressor group and potential diagnostic algorithms, and prospective studies are underway assessing plasma NfL

Prognostic Value of Serum/Plasma Neurofilament Light Chain for COVID-19 Associated Mortality

Given the continued spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), early predictors of coronavirus disease 19 (COVID-19) mortality might improve patients outcomes. Increased levels of circulating neurofilament light chain (NfL), a biomarker of neuro-axonal injury, have been observed in patients with severe COVID-19. We investigated whether NfL provides non-redundant clinical value to previously identified predictors of COVID-19 mortality. We measured serum or plasma NfL concentrations in a blinded fashion in 3 cohorts totaling 338 COVID-19 patients. In cohort 1, we found significantly elevated NfL levels only in critically ill COVID-19 patients compared to healthy controls. Longitudinal cohort 2 data showed that NfL is elevated late in the course of the disease, following two other prognostic markers of COVID-19: decrease in absolute lymphocyte count (ALC) and increase in lactate dehydrogenase (LDH). Significant correlations between LDH and ALC abnormalities and subsequent rise of NfL implicate multi-organ failure as a likely cause of neuronal injury at the later stages of COVID-19. Addition of NfL to age and gender in cohort 1 significantly improved the accuracy of mortality prediction and these improvements were validated in cohorts 2 and 3. In conclusion, although substantial increase in serum/plasma NfL reproducibly enhances COVID-19 mortality prediction, NfL has clinically meaningful prognostic value only close to death, which may be too late to alter medical management. When combined with other prognostic biomarkers, rising longitudinal NfL measurements triggered by LDH and ALC abnormalities would identify patients at risk of COVID-19 associated mortality who might still benefit from escalated care.

Minimal genetically encoded tags for fluorescent protein labeling in living neurons

Modern light microscopy, including super-resolution techniques, has brought about a demand for small labeling tags that bring the fluorophore closer to the target. This challenge can be addressed by labeling unnatural amino acids (UAAs) with bioorthogonal click chemistry. The minimal size of the UAA and the possibility to couple the fluorophores directly to the protein of interest with single-residue precision in living cells make click labeling unique. Here, we establish click labeling in living primary neurons and use it for fixed-cell, live-cell, dual-color pulse–chase, and super-resolution microscopy of neurofilament light chain (NFL). We also show that click labeling can be combined with CRISPR/Cas9 genome engineering for tagging endogenous NFL. Due to its versatile nature and compatibility with advanced multicolor microscopy techniques, we anticipate that click labeling will contribute to novel discoveries in the neurobiology field.

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.

Serum neurofilament light chain level as a predictor of cognitive stage transition

Background Neurofilament light chain (NFL) level has been suggested as a blood-based biomarker for neurodegeneration in dementia. However, the association between baseline NFL levels and cognitive stage transition or cortical thickness is unclear. This study aimed to investigate whether baseline NFL levels are associated with cognitive stage transition or cortical thickness in mild cognitive impairment (MCI) and cognitively unimpaired (CU) participants. Methods This study analyzed data on participants from the independent validation cohort of the Korea Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer’s disease (KBASE-V) study. Among the participants of KBASE-V study, 53 MCI and 146 CU participants who were followed up for ≥ 2 years and had data on the serum NFL levels were eligible for inclusion in this study. Participants were classified into three groups according to baseline serum NFL levels of low, middle, or high. Results The Kaplan–Meier analysis showed association between the serum NFL tertiles and risk of cognitive stage transition in MCI (P = 0.002) and CU (P = 0.028) participants, analyzed separately. The same is true upon analysis of MCI and CU participants together (P < 0.001). In MCI participants, the highest serum NFL tertile and amyloid-beta positivity were independent predictors for cognitive stage transition after adjusting for covariates. For CU participants, only amyloid-beta positivity was identified to be an independent predictor. Conclusion The study shows that higher serum NFL tertile levels correlate with increased risk of cognitive stage transition in both MCI and CU participants. Serum NFL levels were negatively correlated with the mean cortical thickness of the whole-brain and specific brain regions.

Cerebrospinal fluid neurofilament light chain levels in CLN2 disease patients treated with enzyme replacement therapy normalise after two years on treatment

Classic late infantile neuronal ceroid lipofuscinosis (CLN2 disease) is caused by a deficiency of tripeptidyl-peptidase-1. In 2017, the first CLN2 enzyme replacement therapy (ERT) cerliponase alfa (Brineura) was approved by the FDA and EMA. The CLN2 disease clinical rating scale (CLN2 CRS) was developed to monitor loss of motor function, language and vision as well as frequency of generalised tonic clonic seizures. Using CLN2 CRS in an open label clinical trial it was shown that Brineura slowed down the progression of CLN2 symptoms. Neurofilament light chain (NfL) is a protein highly expressed in myelinated axons. An increase of cerebrospinal fluid (CSF) and blood NfL is found in a variety of neuroinflammatory, neurodegenerative, traumatic, and cerebrovascular diseases. We analysed CSF NfL in CLN2 patients treated with Brineura to establish whether it can be used as a possible biomarker of response to therapy. Newly diagnosed patients had CSF samples collected and analysed at first treatment dose and up to 12 weeks post-treatment to look at acute changes. Patients on a compassionate use programme who were already receiving ERT for approximately 1yr had CSF samples collected and NfL analysed over the following 1.3 years (2.3 years post-initiation of ERT) to look at long-term changes. All newly diagnosed patients we investigated with classical late infantile phenotype had high NfL levels >2000 pg/ml at start of treatment. No significant change was observed in NfL up to 12 weeks post-treatment. After one year of ERT, two out of six patients still had high NfL levels, but all patients showed a continued decrease, and all had low NfL levels after two years on ERT. NfL levels appear to correspond and predict improved clinical status of patients on ERT and could be useful as a biomarker to monitor neurodegeneration and verify disease modification in CLN2 patients on ERT.