Search Results (60)

Background and Objectives: Neuromyelitis optica spectrum disorder (NMOSD) and MOG antibody-associated disease (MOGAD) are distinct autoimmune demyelinating disorders of the central nervous system, characterized by different pathological and clinical features. Reliable biomarkers are essential for accurate diagnosis and monitoring of disease activity. Glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) are promising candidates, reflecting astrocytic and axonal damage, respectively. Materials and Methods: To investigate the relationship between astroglial (GFAP) and neuronal (NfL) protein levels in the peripheral blood, 89 plasma samples were analyzed using Simoa immunoassays. The concentrations of pNfL and pGFAP were measured in three groups: AQP4-IgG-positive NMOSD patients (n = 18), MOGAD patients (n = 12), and healthy controls (HCs, n = 19). Statistical analyses assessed group differences, correlations, and the predictive value of biomarkers for disease activity. Results: Both NMOSD and MOGAD patients exhibited elevated pNfL compared with controls, indicating neuroaxonal injury. No significant differences in pNfL, pGFAP, or pGFAP/pNfL ratios were observed between patient groups. The pGFAP levels and the pGFAP/pNfL ratio were significantly higher in NMOSD patients, particularly during attacks, indicating prominent astrocyte damage. Correlations revealed associations between biomarker levels, disability, and disease duration. pNfL demonstrated high accuracy in predicting recent relapses (AUC = 0.906), whereas pGFAP showed moderate predictive capacity (AUC = 0.638). Elevated pNfL and pGFAP levels were associated with an increased likelihood of relapse within six months. Conclusions: Plasma NfL and GFAP are promising biomarkers for assessing tissue injury and disease activity in NMOSD and MOGAD. NfL predicts relapses, while GFAP primarily reflects astrocytic damage in NMOSD. Longitudinal studies are warranted to validate these biomarkers and establish clinical thresholds for disease management. Full article

Alzheimer’s disease (AD) is a progressive neurodegenerative condition representing the most common cause of dementia and currently affects millions of people worldwide. The clinical presentation includes memory impairment, cognitive decline, and neuropsychiatric symptoms, reflecting pathological hallmarks such as β-amyloid (Aβ) plaques, neurofibrillary tangles, synaptic dysfunction, and neuroinflammation. Despite being the gold standard for detecting amyloid and tau pathologies in vivo, cerebrospinal fluid (CSF) biomarkers and positron emission tomography (PET) imaging are not widely used in the clinical setting because of invasiveness, high costs, and restricted accessibility. Recent advances in blood-based biomarkers offer a promising and minimally invasive tool for early detection, diagnosis, and monitoring of AD. Ultra-sensitive analytical platforms, including single-molecule arrays (Simoa) and immunoprecipitation-mass spectrometry, now enable reliable quantification of plasma Aβ isoforms, phosphorylated tau variants (p-Tau181, p-Tau217, p-Tau231), neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP). In addition, blood biomarkers reflecting oxidative stress, neuroinflammation, synaptic disruption and metabolic dysfunction are under active investigation. This narrative review synthesizes current evidence on blood-based biomarkers in AD, emphasizing their biological relevance, diagnostic accuracy, and clinical applications. Finally, we highlight forthcoming challenges, such as standardization, and future directions, including the use of artificial intelligence in precision medicine. Full article

Background: Neurofilament light chain (NfL) is a promising biomarker of neuroaxonal injury, increasingly used to monitor neurodegeneration in Alzheimer’s disease (AD). Multiple analytical platforms are available for NfL quantification in cerebrospinal fluid (CSF), but data on cross-platform consistency remain limited. Objective: This pilot study aimed to provide CSF NfL concentrations measured using Simoa and Lumipulse immunoassays in patients with biologically confirmed AD. Methods: Twenty-eight patients with cognitive impairment fulfilling the biological criteria for AD were enrolled. CSF NfL levels were measured using both Simoa and Lumipulse immunoassays. Statistical analyses assessed intra-individual agreement, correlation between platforms, and associations with cognitive status. Results: NfL concentrations measured with Simoa and Lumipulse showed a strong positive correlation between platforms (Spearman’s ρ = 0.965, p < 0.001), demonstrating excellent analytical concordance. Conclusions: In this pilot study, Simoa and Lumipulse yielded strongly correlated CSF NfL measurements, providing initial evidence of cross-platform consistency. However, these findings require confirmation in larger and diverse cohorts before definitive validation. Full article

Background and Objectives: Multiple sclerosis (MS) is a chronic autoimmune, inflammatory, and neurodegenerative central nervous system disease. Neurodegeneration plays a central role in long-term disease progression. Materials and Methods: This cross-sectional study examined the relationship between neurodegenerative biomarkers, namely plasma neurofilament light chain (pNfL) levels and MRI-derived brain volume measurements, and clinical outcomes in 49 patients with relapsing–remitting multiple sclerosis (RRMS). Plasma NfL levels were quantified using Simoa technology, while MRI data was analyzed via FreeSurfer to measure volumes of grey and white matter, specific brain structures, and ventricular sizes. Cognitive performance was assessed using the Symbol Digit Modalities Test (SDMT) and Brief Visuospatial Memory Test-Revised (BVMT-R). Disability was evaluated using the Expanded Disability Status Scale (EDSS). Results: The results indicated significant positive correlations between SDMT scores and volumes of grey matter, white matter, and various subcortical structures, suggesting that preserved brain volume is linked to better cognitive performance. Negative correlations were observed between SDMT scores and ventricular volumes, as well as between SDMT scores and EDSS scores, implying that cognitive decline corresponds with structural brain deterioration and increased disability. No significant associations were found between BVMT-R scores and imaging data or disability measures. Plasma NfL levels showed significant correlations with early disease relapses and enlargement of the third and fourth ventricles, but not with brain volume, cognitive tests, or EDSS scores. Conclusions: These findings indicate that MRI-based brain volumetrics, particularly grey and white matter measures, are stronger indicators of cognitive function and disability in RRMS than plasma NfL. Full article

Background: There is growing interest in the potential role of manganese (Mn) in the development of Alzheimer’s Disease and related dementias (ADRD). Methods: In this nested pilot study of a ferroalloy worker cohort, we investigated the impact of chronic occupational Mn exposure on cognitive function through β-amyloid (Aβ) deposition and multi-omics profiling. We evaluated six male Mn-exposed workers (median age 63, exposure duration 31 years) and five historical controls (median age: 60 years), all of whom had undergone brain PET scans. Exposed individuals showed significantly higher Aβ deposition in exposed individuals (p < 0.05). The average annual cumulative respirable Mn was 329.23 ± 516.39 µg/m³ (geometric mean 118.59), and plasma Mn levels were significantly elevated in the exposed group (0.704 ± 0.2 ng/mL) compared to controls (0.397 ± 0.18 in controls). Results: LC-MS/MS-based pathway analyses revealed disruptions in olfactory signaling, mitochondrial fatty acid β-oxidation, biogenic amine synthesis, transmembrane transport, and choline metabolism. Simoa analysis showed notable alterations in ADRD-related plasma biomarkers. Protein microarray revealed significant differences (p < 0.05) in antibodies targeting neuronal and autoimmune proteins, including Aβ (25–35), GFAP, serotonin, NOVA1, and Siglec-1/CD169. Conclusion: These findings suggest Mn exposure is associated with neurodegenerative biomarker alterations and disrupted biological pathways relevant to cognitive decline. Full article

Toxic oil syndrome (TOS) is a multisystemic disease that emerged in Spain in 1981 due to the ingestion of aniline-adulterated rapeseed oil fraudulently sold as olive oil. Although neurological sequelae, including cognitive deficits, have been documented in long-term survivors, it remains unclear whether TOS leads to chronic or progressive neurodegeneration. In this case-control study, we measured blood concentrations of neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), and phosphorylated tau 217 (pTau217) in 50 individuals with clinically confirmed TOS and 50 matched healthy controls. Biomarkers were quantified using ultrasensitive immunoassay platforms (Quanterix SIMOA SR-X and Fujirebio Lumipulse G600II). Group differences were evaluated using non-parametric tests, and multiple linear regression was applied to assess associations between biomarkers and clinical variables. While NfL levels were slightly higher in TOS patients (p = 0.025), no significant group differences were observed for pTau217 or GFAP. Age was a consistent predictor of biomarker levels, particularly for GFAP and pTau217, and female sex was independently associated with higher GFAP concentrations. Lower educational attainment was linked to increased NfL levels. Clinical status (TOS vs. control) did not significantly predict biomarker concentrations in any model. These findings suggest no evidence of overt or ongoing neurodegeneration in long-term TOS survivors as detected by current blood biomarkers. However, the possibility of subtle, compartmentalized, or slowly evolving neurotoxic processes cannot be excluded. Future longitudinal studies incorporating serial biomarker assessments, advanced neuroimaging, and oxidative stress markers are warranted to clarify the long-term neurological consequences of TOS and to detect subclinical trajectories of delayed neurotoxicity in this population. Full article

Recent studies show that patients with Alzheimer’s disease (AD) harbor specific methylation marks in the brain that, if accessible, could be used as epigenetic biomarkers. Liquid biopsy enables the study of circulating cell-free DNA (cfDNA) fragments originated from dead cells, including neurons affected by neurodegenerative processes. Here, we isolated and epigenetically characterized plasma cfDNA from 35 patients with AD and 35 cognitively healthy controls by using the Infinium^® MethylationEPIC BeadChip array. Bioinformatics analysis was performed to identify differential methylation positions (DMPs) and regions (DMRs), including APOE ε4 genotype stratified analysis. Plasma pTau181 (Simoa) and cerebrospinal fluid (CSF) core biomarkers (Fujirebio) were also measured and correlated with differential methylation marks. Validation was performed with bisulfite pyrosequencing and bisulfite cloning sequencing. Epigenome-wide cfDNA analysis identified 102 DMPs associated with AD status. Most DMPs correlated with clinical cognitive and functional tests including 60% for Mini-Mental State Examination (MMSE) and 80% for Global Deterioration Scale (GDS), and with AD blood and CSF biomarkers. In silico functional analysis connected 30 DMPs to neurological processes, identifying key regulators such as SPTBN4 and APOE genes. Several DMRs were annotated to genes previously reported to harbor epigenetic brain changes in AD (HKR1, ZNF154, HOXA5, TRIM40, ATG16L2, ADAMST2) and were linked to APOE ε4 genotypes. Notably, a DMR in the HKR1 gene, previously shown to be hypermethylated in the AD hippocampus, was validated in cfDNA from an orthogonal perspective. These results support the feasibility of studying cfDNA to identify potential epigenetic biomarkers in AD. Thus, liquid biopsy could improve non-invasive AD diagnosis and aid personalized medicine by detecting epigenetic brain markers in blood. Full article

Experimental autoimmune encephalomyelitis (EAE) is a preclinical animal model widely used to study multiple sclerosis (MS). Blood-based analytes, including cytokines and neural biomarkers are the predictors of neurodegeneration, disease activity, and disability in patients with MS. However, understudied confounding factors cause variation in reports on EAE across animal strains/studies, limiting the utility of these biomarkers for predicting disease activity. In this study, we investigated blood-based analyte profiles, including neural markers (NFL and GFAP) and cytokines (IL-6, IL-17, IL-12p70, IL-10, and TNF-α), in two clinically distinct EAE models: relapsing-remitting (RR)-EAE and chronic-EAE. Ultrasensitive single-molecule array technology (SIMOA, Quanterix) was used to profile the analytes in the blood plasma of mice at the acute, chronic, and progressive phases of disease. In both models, NFL was substantially increased during post-disease onset across all phases, with a pronounced increase observed in chronic-EAE. The leakage of GFAP into peripheral blood was also greater after disease onset in both EAE models, especially in the acute phase of chronic-EAE. Among all cytokines, only IL-10 had consistently lower levels in both EAE models throughout the course of disease. This study suggests NFL, GFAP, and IL-10 as potential translational predictors of disease activity in EAE, making them potential candidates as surrogate markers for the preclinical testing of therapeutic interventions in animal models of MS. Full article

We aimed to determine whether transient global amnesia (TGA) is associated with alterations in central nervous system (CNS) injury biomarkers—serum neurofilament light chain (sNfL) and serum glial fibrillary acidic protein (sGFAP). In a prospective cohort of TGA patients, blood samples were obtained within 24–48 h of TGA onset (t0) and 6 weeks thereafter (t1). We assessed sNfL and sGFAP levels using the highly sensitive single-molecule array assay and calculated Z-scores adjusted for age, gender, and body mass index (BMI). Demographics, electroencephalography (EEG), and cerebral magnetic resonance imaging (cMRI) findings were also collected. A total of 20 patients were included (median age: 66 years, 70% women). No significant changes in sNfL or sGFAP levels associated with TGA at t0 and t1 were observed. Median sNfL Z-scores were 0.45 (interquartile range [IQR] −0.09, 1.19) at t0 and 0.60 (IQR −0.61, 1.19) at t1. Median sGFAP Z-scores were 0.27 (IQR −0.45, 0.76) at t0 and 0.44 (IQR −0.27, 0.75) at t1. Similarly, in the subgroup of patients with diffusion-weighted imaging (DWI)-positive hippocampal lesions (n = 5/20[25%]), no elevations in blood biomarkers were detected. Our pilot study on neurological blood biomarkers supports the benign nature of TGA, indicating that no CNS tissue damage occurs. Full article

To investigate levels of specific plasma-biomarkers related to neurodegeneration and inflammation in patients with different chronic degenerative retinal diseases, using an ultrasensitive technology called ‘single molecule array’ (SiMoA). Also, to investigate if biomarkers were measurable in the patient’s blood, dependent on age and medical comorbidities, and useful for stratifying the diseases. This exploratory, cross-sectional study recruited 151 adults at the Department of Ophthalmology, Rigshospitalet, Denmark (period 2019 to 2020). Clinical data came from the electronic medical-record system. The study population consisted of 131 patients: 32 with diabetic retinopathy (DR; 51 diabetes, DM), 27 with glaucoma, 53 with inherited retinal degeneration (IRD and 20 healthy controls (HC). Medical comorbidities included organ failure, other active eye diseases, and comorbidities. Three biomarkers, neurofilament-light-chain (NFL), glial-fibrillary-acidic-protein (GFAP), and CXC-motif chemokine ligand 13 (CXCL13), were measured with SiMoA technology. The age-adjusted values were reported as fold differences (FD) with 95% confidence intervals (CI). Increased NFL levels were found in DR patients compared to HCs (FD 1.81 95%CI 1.43, 2.28, p < 0.001, adj-p < 0.001). Similarly increased NFL levels were reported in advanced DR (PDR, DME), compared to both DM (FD 2.52 (95%CI: 1.71; 3.72, p < 0.001, adj-p < 0.001, and FD 2.04 (95%CI: 1.33; 3.12, p < 0.001, adj-p < 0.001), respectively) and HCs (FD 2.35 (95%CI: 1.67; 3.30, p < 0.001, adj-p < 0.001), and FD 1.89 (95%CI: 1.28; 2.79, p < 0.001, adj-p < 0.001) respectively). Independent of comorbidities, decreased NFL-levels were seen in IRD compared to DR (FD 0.49 (95% CI 0.39; 0.61, p < 0.001; adj-p < 0.001), ±comorbidities). Decreased GFAP levels were seen in DM patients compared to HCs (FD 0.69; 95%CI 0.55, 0.87, p = 0.002, adj-p = 0.02), but contrary to an increasing trend in advanced DR compared to DM (-comorbidities). These results imply that these biomarker-tests are useful for detecting and monitoring development of retinopathy in the circulations of diabetes patients. Plasma-biomarkers may be useful to stratify between retinal disease types. Prospective studies are underway to explore this hypothesis in depth. Full article

Background/Objectives: Fabry disease (FD) is an inborn error of the glycosphingolipid metabolism with variable kidney, heart, and central nervous system (CNS) involvement. CNS-related FD manifestations include early ischemic stroke and white matter lesions (WMLs) related to cerebral small-vessel disease (CSVD), possibly resulting in cognitive impairment. We studied 40 adult FD patients (17 male) to assess: (i) prevalence of cerebrovascular and cognitive manifestations in FD and their correlation with heart and renal involvement; and (ii) the potential value of serum neurofilament light chain (NfL) levels as an indicator of WMLs in FD. Methods: Patients underwent detailed diagnostic assessment related to FD, also including Mainz Severity Score Index (MSSI), neuropsychological tests, brain MRI to assess WMLs by the modified Fazekas score (mFS), and NfL determination by single-molecule array (SiMoA) (n = 22 FD patients vs. 15 healthy controls). Results: Overall, 4 FD patients had a history of ischemic stroke and 13/32 patients (40.6%) had an mFS ≥ 1. Almost two-thirds of FD patients (27/39, 69.2%) showed impairment on at least one cognitive test. On univariate analysis, only a reduction in estimated glomerular filtration rate was associated with an increased likelihood of having WMLs on brain MRI. Serum NfL levels were higher in FD patients vs. controls, with a trend toward significance (p = 0.08). Conclusions: Mild-to-moderate CSVD is a characteristic brain “signature” in FD patients. Both cardiac and renal involvement correlate with WML load, but only renal involvement appears to be predictive of CNS damage. Brain microvascular damage is associated with mild cognitive impairment in FD, and serum NfL might represent a potential biomarker of CSVD in FD. Full article

Plasma biomarkers are promising tools for the screening and diagnosis of dementia in clinical settings. We analyzed plasma levels of Alzheimer’s core biomarkers, neurofilament light chain (NfL) and glial fibrillary acid protein (GFAP), through single-molecule Array in 108 patients with Alzheimer’s (AD, cerebrospinal fluid with an amyloid+ tau+ neurodegeneration+ profile), 73 patients with frontotemporal dementia (FTD, 24 with genetic diagnosis), and 54 controls. The best area under the curve (AUC) was used to assess the discriminative power. Patients with AD had lower Aß42/40 ratios and NfL levels, along with higher levels of p-tau181 and GFAP, compared with FTD patients. Single biomarkers discriminated well between dementia patients and controls: the Aß42/40 ratio (AUC:0.86) or GFAP (AUC:0.83) was found for AD, and the NfL (AUC:0.84) was found for FTD patients. However, a combination of two (NfL with p-tau181, or the GFAP/NfL ratio, AUCs ~0.87) or three biomarkers (NfL, P-tau181, and Aß42/40 ratio, AUC: 0.90) was required to distinguish between AD and FTD. Biomarker profiles were similar across different FTD phenotypes, except for carriers of PGRN mutations, who had higher levels of NfL than C9orf72 expansion carriers. In our series, NfL alone provided the best distinction between FTD and controls, while a combination of two or three biomarkers was required to obtain good discrimination between AD and FTD. Full article

Interleukin (IL)-1β is a pro-inflammatory cytokine whose levels are increased in the brains of Alzheimer’s disease (AD) patients. Despite the role of IL-1β in the pathology of AD, the fact that it is expressed at very low levels makes it a challenging cytokine to measure, hence limiting its potential use as a reliable biomarker. Moreover, being able to accurately and reliably measure the levels of IL-1 β in blood makes it possible to evaluate this cytokine as a potential biomarker of the inflammatory response in AD. In this study, we compared three quantification methodologies, Meso-Scale Discovery (MSD), both V-Plex and S-Plex versions, and Quanterix’s SIMOA (Single-Molecule Array), to measure IL-1β in the serum of AD patients and age-matched controls. These assays are routinely used to measure IL-1β serum levels with high specificity and sensitivity in human AD patients, yet to the best of our knowledge, no study has compared all three techniques for their accuracy to measure IL-1β as biomarkers. Our findings indicate the two MSD assays can be used to measure IL-1β levels in AD and control serum, but the SIMOA assay showed the highest receiver operating characteristics (ROCs), with an area under the curve (AUC) of 0.9532, which can be compared to the AUC values for the V-Plex assay, 0.5660, and the S-Plex assay, 0.6632. Taken together, these data show that although all technologies are useful in the measurement of IL-1β in the blood, the SIMOA IL-1β 3.0 assay is more reliable and sensitive in measuring biomarkers of AD. Full article

Impaired renal function can influence biomarker levels through mechanisms involving blood–brain barrier integrity and clearance pathways; however, the impact of variations within normal renal function remains unclear. The main aim of this study was to determine whether adjustment for the specific level of renal function is necessary when renal function remains within physiological levels. We studied n = 183 patients (NID n = 122; other neurological diseases n = 39; somatoform controls n = 22) who underwent lumbar puncture at University Hospital Frankfurt. Serum and cerebrospinal fluid (CSF) levels of neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), total tau protein (tTAU), and ubiquitin C-terminal hydrolase-L1 (UCHL1) were measured using the single molecule array (SIMOA) technique. Estimated glomerular filtration rate (eGFR) correlated negatively with CSF GFAP (r = −0.217, p = 0.004) and serum NfL (r = −0.164, p = 0.032). Patients with impaired renal function exhibited higher CSF NfL (p = 0.036) and CSF GFAP (p = 0.026) levels. However, these findings did not remain significant after adjusting for BMI and age. Importantly, in patients with normal renal function, no significant correlations with eGFR and biomarker levels were observed after adjustment. Our findings indicate that serum and CSF concentrations of NfL, GFAP, tTAU, and UCHL1 are not significantly affected by fluctuations in physiological kidney function but emphasize the importance of considering comorbidities in impaired renal function when interpreting biomarker levels. Full article

Despite the success of combination antiretroviral therapy (cART) to suppress HIV replication, HIV persists in a long-lived reservoir that can give rise to rebounding viremia upon cART cessation. The translationally active reservoir consists of HIV-infected cells that continue to produce viral proteins even in the presence of cART. These active reservoir cells are implicated in the resultant viremia upon cART cessation and likely contribute to chronic immune activation in people living with HIV (PLWH) on cART. Methodologies to quantify the active reservoir are needed. Here, an automated immunocytochemistry (ICC) assay coupled with computational image analysis to detect and quantify intracellular Gag capsid protein (CA) is described (CA-ICC). For this purpose, fixed cells were deposited on microscopy slides by the cytospin technique and stained with antibodies against CA by an automated stainer, followed by slide digitization. Nuclear staining was used to count the number of cells in the specimen, and the chromogenic signal was quantified to determine the percentage of CA-positive cells. In comparative analyses, digital ELISA, qPCR, and flow cytometry were used to validate CA-ICC. The specificity and sensitivity of CA-ICC were assessed by staining a cell line that expresses CA (MOLT IIIB) alongside a control cell line (Jurkat) devoid of this marker, as well as peripheral blood mononuclear cells (PBMCs) from HIV seronegative donors before or after ex vivo infection with an HIV laboratory strain. The sensitivity of CA-ICC was further assayed by spiking MOLT IIIB cells into uninfected Jurkat cells in limiting dilutions. In those analyses, CA-ICC could detect down to 10 CA-positive cells per million with a sensitivity superior to flow cytometry. To demonstrate the application of CA-ICC in pre-clinical research, bulk PBMCs obtained from mouse and non-human primate animal models were stained to detect HIV CA and SIV p27, respectively. The level of intracellular CA quantified by CA-ICC in PBMCs obtained from animal models was associated with plasma viral loads and cell-associated CA measured by qPCR and ELISA, respectively. The application of CA-ICC to evaluate the activity of small-molecule targeted activator of cell-kill (TACK) in clinical specimens is presented. Overall, CA-ICC offers a simple imaging method for specific and sensitive detection of CA-positive cells in bulk cell preparations. Full article