The objective of this study was to determine, at the time of diagnosis, a CSF and MRI profile of intrathecal compartmentalized inflammation predictive of progression independent of relapse activity (PIRA) in early relapsing-remitting multiple sclerosis (RRMS).

This five-year prospective study included 80 treatment-naïve patients with RRMS enrolled at time of diagnosis. All patients underwent a lumbar puncture, regular neurologic evaluations including an Expanded Disability Status Scale (EDSS) assessment every 6 months, and an annual 3T brain MRI. PIRA was defined as having a confirmed disability progression independent of relapse activity. CSF levels of 68 inflammatory molecules were evaluated in combination with white matter and cortical lesion number (CLn) and volume, and regional gray matter thickness and volume.

During the follow-up, 23 patients with RRMS (28.8%) experienced PIRA. At diagnosis, participants with PIRA were older (44.0 ± 10.7 vs 37.4 ± 12.4, p = 0.017) and with more disability (median EDSS score [interquartile range] of 3 [range 2-4] for PIRA vs 1.5 [range 1-2] for no PIRA group, p < 0.001). Random forest selected LIGHT, CXCL13, sTNFR1, sTNFR2, CCL7, MIF, sIL6Rbeta, IL35, CCL2, and IFNβ as the CSF markers best associated with PIRA. sTNFR1 (hazard ratio [HR] 10.11 [2.61-39.10], p = 0.001), sTNFR2 (HR 5.05 [1.63-15.64], p = 0.005), and LIGHT (HR 1.79 [1.11-2.88], p = 0.018) were predictors of PIRA at regression analysis. Baseline thalamus volume (HR 0.98 [0.97-0.99], p = 0.005), middle frontal gyrus thickness (HR 0.05 [0.01-0.72], p = 0.028), and CLn (HR 1.15 [1.05-1.25], p = 0.003) were MRI predictors of PIRA.

A specific intrathecal inflammatory profile associated with TNF superfamily markers, CLn, and atrophy of several cortical and deep gray matter regions, assessed at time of diagnosis, is predictive of PIRA in early MS.

Can plasma biomarkers as well as cerebrospinal fluid (CSF) perform in the separation of amyloid-beta-positive (Aβ+) vs amyloid-beta-negative (Aβ-) groups across an age range seen in an NHS cognitive disorder clinic?

As part of the routine diagnostic investigation of 111 clinic patients who had contemporaneous blood and CSF samples taken, patients were categorised into Aβ+ and Aβ- groups based on their CSF in an Aβ42/40 ratio. We then evaluated four single molecule array (Simoa) Quanterix assays, quantifying single plasma analytes and ratios (p-tau217, p-tau217/Aβ42 ratio, p-tau181, p-tau181/Aβ42 ratio and Aβ42/40 ratio) in their ability to distinguish between these groups and the effect of age.

The median (range) age of participants was 66 (55-79) years with 48 females (43.2%). The areas under the curve (AUC), not accounting for age, for the ability to discriminate Aβ+ from Aβ- groups were plasma p-tau217 AUC=0.94, Aβ42/40 AUC=0.78 and p-tau181 AUC=0.77. Combining p-tau217/Aβ42 increased the AUC to 0.97. The difference between the groups was influenced by age with less separation in older individuals: a significant negative interaction term between age and group for plasma p-tau217 concentrations (-0.037, p=0.013) and p-tau217/Aβ42 ratio (-0.007, p=0.008).

There was variable performance of plasma biomarkers to recapitulate the CSF assay. Both p-tau217 and p-tau217/Aβ42 showed excellent promise as surrogates of CSF amyloid status, although with slightly reduced performance in older individuals. There was poorer discriminatory ability for p-tau181 and Aβ42/40. Further research is needed to address potential age-related confounds.

While Parkinson's disease is a low dopamine neurodegenerative disorder, Schizophrenia is considered a high dopamine psychiatric disorder. Pharmacological interventions that are directed to normalize dopamine concentrations in the mid-brain for an extended duration lead to unintended consequences. Parkinson's disease patients experience psychosis, and Schizophrenia patients develop extra-pyramidal symptoms due to dopamine levels overshooting their physiological range. An objective monitoring technique is therefore required for better therapeutic efficacy in these two neurological diseases.

A rapid and sensitive assay for α-Synuclein based on magnetic enrichment and enzymatic fluorescent signal generation was developed. This assay has been benchmarked with conventional ELISA and validated in 53 CSF and 36 serum samples.

Developed assay from an experimental perspective has a sensitivity of less than 10 pg/mL; requires a turnaround time of 45 mins; and uses 2 µL of CSF/serum fluid samples to quantify alpha synuclein. From a utility perspective, the assay showed (a) a two-fold linearity across clinical phenotypes of Parkinson's disease, neurological controls, and schizophrenia patients; (b) variation between the naïve and treated patients; (c) correlation with severity of the disease. From a diagnostic perspective, the serum-based assay had a 100 % specificity and a minimum of 67 % sensitivity in differentiating naïve patients from treated patients; the CSF/serum-based assays had a minimum of 91 % specificity and a minimum of 85 % sensitivity in differentiating patients from neurological controls.

The developed assay can be used to quantify alpha-synuclein in serum and CSF samples, thereby setting a translational platform for diagnosis, prognosis, and monitoring pharmacotherapy patients with Parkinson's disease and Schizophrenia.

Theory of Mind (ToM) is a complex socio-cognitive subdomain that is under-researched in neurodegenerative disorders, particularly in persons with primary progressive aphasia. We studied 14 persons with non-fluent/agrammatic variant primary progressive aphasia (nfaPPA), and asked two questions: (1) whether persons with nfaPPA have intact or impaired ToM, with emphasis on their false belief attribution abilities, relative to healthy controls; and (2) whether false-belief attribution (a component of ToM) is associated with their syntactic and executive function (EF) abilities. False belief understanding was tested through nonverbal videos, with participants deciding whether the story ending was an appropriate end of each video scenario or not. Syntactic production abilities were measured through repetition of syntactically simple and complex sentences (comprising length-matched complement and adjunct sentences), and EF tasks, specifically, a digit-back and an attention-shifting task. Persons with nfaPPA were less accurate than controls in adapting their reasoning to the false beliefs of other agents in the nonverbal videos of the false belief attribution task. Their false belief attribution performance was significantly predicted primarily by their syntactic production, followed by their EF. The overall findings suggest that persons with nfaPPA may have impaired performances in ToM tasks, due to impairments in basic non-social cognitive functioning, such as syntactic and EF abilities.

To investigate whether renal function impacts CSF κ-FLC concentration and/or κ-FLC index.

Patients with non-inflammatory neurological diseases were eligible. κ-FLC index was calculated as (CSF κ-FLC/serum κ-FLC)/albumin quotient. Structural equation modeling (SEM) was used to evaluate the direct influence of GFR on serum κ-FLC concentration and albumin quotient (Qalb), and via these two variables the indirect influence on CSF κ-FLC concentration.

A total of 129 patients with a median age of 65 years and 42 % females were included. κ-FLC index ranged from 0.57 to 3.56 and glomerular filtration rate (GFR) ranged from 17 to 128 mL/min/1.73 m2. While a correlation of GFR with CSF κ-FLC concentration was observed (r= -0.52, p<0.001), there was no statistically significant correlation with κ-FLC index (r=0.14, p=0.113). SEM revealed that higher age was associated with lower GFR (β= -0.53), which led to higher serum κ-FLC concentration (β= -0.45) and higher Qalb (β= -0.17), while CSF κ-FLC concentration increased with serum κ-FLC concentration (β=0.75) and Qalb (β=0.39), indicating that GFR did not directly influence CSF κ-FLC concentration (RMSEA=0.043).

CSF κ-FLC concentration is not directly affected by renal function. The κ-FLC index compensates for renal function effects by factoring in serum κ-FLC concentration and Qalb. κ-FLC index can be interpreted without considering renal function.

Alzheimer's disease (AD) remains a significant global health challenge, characterized by its progressive neurodegeneration and cognitive decline. The urgent need for early diagnosis and effective treatment necessitates the identification of reliable biomarkers that can illuminate the underlying pathophysiology of AD. This review provides a comprehensive overview of the latest advancements in biomarker research, focusing on their applications in diagnosis, prognosis, and therapeutic development. We delve into the multifaceted landscape of AD biomarkers, encompassing molecular, imaging, and fluid-based markers. The integration of these biomarkers, including amyloid-β and tau proteins, neuroimaging modalities, cerebrospinal fluid analysis, and genetic risk factors, offers a more nuanced understanding of AD's complex etiology. By leveraging the power of precision medicine, biomarker-driven approaches can enable personalized treatment strategies and enhance diagnostic accuracy. Moreover, this review highlights the potential of biomarker research to accelerate drug discovery and development. By identifying novel therapeutic targets and monitoring disease progression, biomarkers can facilitate the evaluation of experimental treatments and ultimately improve patient outcomes. In conclusion, this review underscores the critical role of biomarkers in advancing our comprehension of AD and driving the development of effective interventions. By providing a comprehensive overview of the current state-of-the-art, this work aims to inspire future research and contribute to the goal of conquering AD.

Multiple sclerosis (MS) is a chronic autoimmune disorder affecting the central nervous system, often emerging in early adulthood and representing a leading cause of neurological disability in young adults. Diagnosing MS involves a combination of clinical assessment, imaging and laboratory tests, with cerebrospinal fluid (CSF)-specific immunoglobulin G (IgG) oligoclonal bands (OCB) being an important marker for fulfilling the dissemination in time criteria. A recent survey of Canadian clinical laboratories highlighted considerable variation in OCB reporting practices nationwide, spanning quality control (QC) practices, acceptable time limits between paired CSF and serum sample collections, protocols for reporting band counts, interpretation and reporting of mirrored patterns, testing panels, and interpretive thresholds. These inconsistencies impact patient care and the comparability of laboratory results across different laboratories. The Harmonized CSF Analysis for MS Investigation (hCAMI) subcommittee of the Canadian Society of Clinical Chemists Reference Interval Harmonization Working Group was established to generate recommendations for laboratory processes and reporting of CSF OCB and associated tests supporting MS diagnosis. This review serves as a foundation for these efforts, summarizing the available evidence in areas where practice variations have been noted. This review begins by examining current practices and guidelines for standardized quality assurance, including optimal QC materials, frequency, documentation, and participation in external quality assurance programs. The disparity between paired CSF and serum sample acceptability time limits was further examined by reviewing current practices and recommendations as well as compiling evidence on IgG synthesis, turnover rate, biological variation, and stability in CSF and serum samples. Additionally, this review addresses the lack of consensus on reporting the number of CSF-specific and CSF-serum matched bands, focusing on interpreter variability and clinical utility. Contributing factors and clinical implications of mirror patterns, including discussion on monoclonal gammopathies and cases of matched bands of differing staining intensity, is provided. Testing panel components including adjunctive CSF tests, such as the IgG index, to support MS investigations despite their absence from clinical guidelines is also discussed. This review also provides a comprehensive analysis of current practices, guidelines, and the evidence surrounding different cutoffs for IgG index and CSF-specific bands.

Finally, the review considers emerging biomarkers, such as the kappa free light chain index and serum neurofilament light chain, which show promise for MS diagnosis and management. This comprehensive review of current practices, guidelines, and evolving evidence will guide the hCAMI subcommittee's efforts to harmonize CSF OCB analysis and improve MS diagnosis.

Beta-synuclein (β-syn), measured at N-terminal epitopes, is an emerging cerebrospinal fluid (CSF) biomarker for synaptic degeneration in Alzheimer's disease (AD). Targeting the mid-region or C-terminus of β-syn may enhance analytical specificity due to the distinct structures of these regions across the synuclein protein family, unlike targeting the N-terminus, which is conserved across the family. This study aimed to confirm that β-syn is a promising CSF biomarker in AD, using novel assays designed to target different regions of β-syn, to investigate whether these regions are differentially affected in AD.

We developed two novel CSF β-syn-specific ELISAs targeting mid-region and C-terminus epitopes and assessed their analytical performance. Using these novel assays in combination with the established N-terminus ELISA, we analyzed a proof-of-concept cohort comprising biomarker-confirmed AD (n = 25) and non-AD subjects (n = 25) and a larger clinical cohort (n = 160) from the Amsterdam Dementia Cohort, wich included 41 individuals with subjective cognitive decline (SCD, controls; AD biomarker negative; 64.3 ± 3.3 years, 23 females), 39 with SCD (AD biomarker positive; 65.7 ± 3.1 years, 17 females), 40 with mild cognitive impairment due to AD (MCI-AD; 66.2 ± 2.9 years, 20 females), and 40 with AD dementia (AD-dem; 65.3 ± 3.4 years, 20 females).

Both the mid-region and C-terminus assays demonstrated reliable analytical performance. All assays consistently detected β-syn in all clinical samples above their limits of detection, with a good average intra-assay coefficient of variation (range of the three assays: 2.7-6.5%CV) in the proof-of-concept cohort and clinical cohort (range of the three assays: 3.9-7.5%CV). CSF β-syn levels, with all the assays, were significantly elevated in all the AD groups compared with the controls in both cohorts. The diagnostic performance of the assays for distinguishing AD patients from controls was comparable (Delong's p > 0.05, AUC 0.71-0.80). Notably, mid-region β-syn significantly differentiated SCD-AD patients from AD-dem patients (p = 0.035) and MCI-AD patients at a trend level. Only mid-region and C-terminal levels correlated with MMSE scores (mid-region rho = -0.22, p = 0.006; C-terminal rho = -0.19, p = 0.016; N-terminus rho = -0.14, p = 0.069).

Our novel assays demonstrated good analytical and clinical performance. CSF β-syn reliably indicates early synaptic degeneration in AD. The mid-region assay uniquely differentiated SCD-AD from AD-dem, showing promise for early disease detection.

Evidence on neurochemical mechanisms underlying response to apheresis in steroid-refractory Multiple Sclerosis (MS) attacks is limited.

To examine the effect of immunoadsorption (IA) versus plasma exchange (PLEX) on serum immunological parameters [IgG, IgA, IgM, kappa- and lambda-immunoglobulin free light chains (κ-FLC, λ-FLC), CXCL13, CXCL12] and the predictive value of these parameters on response to apheresis.

Pre- and postprocedural serum samples of 38 participants (IA: n = 19, PLEX: n = 19) from the IAPEMS trial (NCT02671682), conducted in our tertiary centre, were examined.

Serum immunoglobulins were strongly reduced after both procedures (IgG: IA median -96.04%; PLEX median -85.98%). κ-FLC levels were reduced after PLEX (median -34.74%), not affected by IA. Both procedures caused a decrease in λ-FLC levels. CXCL13 slightly increased after PLEX (median +24.16%), conversely decreased after IA (median -21.92%). CXCL12 levels were reduced after IA (median -45.69%), but not significantly altered after PLEX. None of the serum parameters evaluated showed predictive value for apheresis response.

IA and PLEX have a differential effect on serum immunological parameters. IA appears to reduce B-cell derived inflammation more effectively. This finding requires further evaluation and comparative analysis with clinical outcomes, especially in the context of the efficacy of B-cell therapies in treating MS.

Acute lymphoblastic leukaemia (ALL) is a rare and heterogeneous disease. The ALLTogether consortium has implemented a treatment protocol to improve outcome and reduce treatment-related toxicity across much of Europe. The consortium provides the opportunity to design translational research on patient material stored in national biobanks. However, there are currently no standardized guidelines for the types of material, processing, and storage for leukaemia biobanking. To address this gap, we conducted a modified Delphi survey among 53 experts in different roles related to leukaemia. The first round consisted of 63 statements asking for level of agreement. The second round refined some to reach consensus, using yes-no and multiple-option answers. Key recommendations include cryopreservation of cells from diagnosis, post-induction, post-consolidation, and relapse, with at least two aliquots of plasma and serum, and cerebrospinal fluid from diagnosis, day15, and post-induction. It was advised to distribute cells across multiple vials for various research projects, and to collect data on sample processing, cell viability, and blast percentage. Quality monitoring and user feedback were strongly recommended. The Delphi survey resulted in strong recommendations that can be used by national biobanks to harmonize storage of samples from patients with ALL and ensure high-quality cryopreserved cells for research studies.

Dysregulated immune activation plays a key role in the pathogenesis of neurodegenerative diseases, including frontotemporal dementia (FTD). This study reviews immunological biomarkers associated with FTD and its subtypes. A systematic search of PubMed and Web of Science was conducted for studies published before 1 January 2025, focusing on immunological biomarkers in CSF or blood from FTD patients with comparisons to healthy or neurological controls. A total of 124 studies were included, involving 6686 FTD patients and 202 immune biomarkers. Key findings include elevated levels of GFAP and MCP1/CCL2 in both CSF and blood and consistently increased CHIT1 and YKL-40 in CSF. Complement proteins from the classical activation pathway emerged as promising targets. Distinct immune markers were found to differentiate FTD from Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS), with GFAP, SPARC, and SPP1 varying between FTD and AD and IL-15, HERV-K, NOD2, and CHIT1 differing between FTD and ALS. A few markers, such as Galectin-3 and PGRN, distinguished FTD subtypes. Enrichment analysis highlighted IL-10 signaling and immune cell chemotaxis as potential pathways for further exploration. This study provides an overview of immunological biomarkers in FTD, emphasizing those most relevant for future research on immune dysregulation in FTD pathogenesis.

Amyloid-β (Aβ) positron emission tomography (PET) imaging and cerebrospinal fluid (CSF) biomarkers are now established tools in the diagnostic workup of patients with Alzheimer's disease (AD), and their use is anticipated to increase with the introduction of new disease-modifying therapies. Although these biomarkers are comparable alternatives in research settings to determine Aβ status, biomarker testing in clinical practice requires careful consideration of the strengths and limitations of each modality, as well as the specific clinical context, to identify which test is best suited for each patient. This article provides a comprehensive review of the pathologic processes reflected by Aβ-PET and CSF biomarkers, their performance, and their current and future applications and contexts of use. The primary aim is to assist clinicians in making better-informed decisions about the suitability of each biomarker in different clinical situations, thereby reducing the risk of misdiagnosis or incorrect interpretation of biomarker results. HIGHLIGHTS: Recent advances have positioned Aβ PET and CSF biomarkers as pivotal in AD diagnosis. It is crucial to understand the differences in the clinical use of these biomarkers. A team of experts reviewed the state of Aβ PET and CSF markers in clinical settings. Differential features in the clinical application of these biomarkers were reviewed. We discussed the role of Aβ PET and CSF in the context of novel plasma biomarkers.

Rapid determination of cerebrospinal fluid (CSF) glucose and lactate is required by emergency rooms and intensive care units. Long turnaround time (TAT) on test results negatively impacts timely diagnosis and treatment of neurological infections like meningitis.

The CSF glucose and lactate assays were evaluated on a blood gas analyzer, Radiometer ABL90 Flex Plus. Linearity, limit of quantitation (LOQ), and precision were determined using fresh and spiked patient CSF samples. Fifty-four fresh and 49 frozen CSF samples were used to compare the method againstAbbottArchitectC16000. An inter-laboratory comparison was done across eight hospital sites having ABL90 Flex Plus. The stability of both tests was tested for 48 h at ambient and refrigerated temperatures. Results were compared between centrifuged and uncentrifuged fresh CSF samples to determine if particulate in uncentrifuged samples impacted analysis.

Glucose and lactate assays were linear over a broad analytical range of 1-45 mmol/L and 0-37 mmol/L, respectively, and demonstrated a good correlation with the routine chemistry laboratory method. LOQ was determined as 0.4 mmol/L for CSF glucose with a coefficient of variation (CV) of 14.7 % and 0.2 mmol/L with 0 % CV for CSF lactate respectively. Repeatability and reproducibility show small imprecision for both these assays. Glucose and lactate were stable for over 48 h at room or refrigeration temperatures. Sample particulates had no impact on the measurement. The inter-laboratory comparison was within total allowable error for glucose and lactate.

Acceptable performance characteristics, small sample volume, and rapid TAT make ABL90 Flex Plus an acceptable alternative analyzer for CSF glucose and lactate.

Affective symptoms are prevalent features in people with multiple sclerosis (PwMS). Structural brain changes, as well as cytokine-driven synaptic and network alterations, might contribute to the development of these clinical features. In the present study, we evaluated the association between the cerebrospinal fluid (CSF) levels of the pro-inflammatory cytokine interferon-gamma (IFN-γ) at multiple sclerosis (MS) diagnosis and the subsequent development of depression and anxiety.

PwMS and a negative history for psychiatric disorders were recruited at MS onset. CSF IFN-γ concentrations were measured by Single Molecule Array. Socio-demographic and clinical information was collected, and all subjects underwent brain magnetic resonance imaging (MRI). After a mean follow-up time of 3 years, psychometric assessment was performed. Depressive symptoms were evaluated with the Beck Depression Inventory II, while the State and Trait Anxiety Inventory Y was used to assess anxiety symptoms.

In our sample (n = 28), 21.4 % subjects suffered from clinically significant depression at follow-up, while the prevalence raised at 51.7 % for both state and trait anxiety. Subjects with clinically relevant depression presented greater disability levels at baseline (p = 0.020), as well as more severe state (p = 0.010) and trait (p < 0.001) anxiety at follow-up. Baseline IFN-γ concentrations were significantly higher in subjects who displayed clinically significant depression at follow-up (p = 0.037), an association that was not replicated for state and trait anxiety. No significant associations were found between brain MRI measures and psychiatric symptoms at follow-up.

Proinflammatory cytokines might play a relevant role in the development of affective symptoms, particularly depressive, in PwMS. Their possible predictive value deserves further attention, possibly helping the early detection of at-risk subjects and the implementation of tailored treatments.

The cerebrospinal fluid (CSF) provides a unique glimpse into the central nervous system (CNS) compartment and offers insights into immune processes associated with both healthy immune surveillance as well as inflammatory disorders of the CNS. The latter include demyelinating disorders, such as multiple sclerosis (MS) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), that warrant different therapeutic approaches yet are not always straightforward to distinguish on clinical and imaging grounds alone. Here, we establish a comprehensive phenotypic landscape of the pediatric CSF immune compartment across a range of non-inflammatory and inflammatory neurological disorders, with a focus on better elucidating CNS-associated immune mechanisms potentially involved in, and discriminating between, pediatric-onset MS (MS) and other pediatric-onset suspected neuroimmune disorders, including MOGAD. We find that CSF from pediatric patients with non-inflammatory neurological disorders is primarily composed of non-activated CD4+ T cells, with few if any B cells present. CSF from pediatric patients with acquired inflammatory demyelinating disorders is characterized by increased numbers of B cells compared to CSF of both patients with other inflammatory or non-inflammatory conditions. Certain features, including particular increased frequencies of antibody-secreting cells (ASCs) and decreased frequencies of CD14+ myeloid cells, distinguish MS from MOGAD and other acquired inflammatory demyelinating disorders.

The roles of reactive astrocytes in Alzheimer's disease (AD) and the correlation between plasma glial fibrillary acidic protein (GFAP) and amyloid-β are emerging. Among 133 patients with cognitive complaints from multi-center memory clinics in Thailand, 73 had AD as defined either by cerebrospinal fluid core biomarkers or amyloid PET. Plasma GFAP demonstrated an AUC of 0.74 (95%CI: 0.65-0.83) for detecting AD and showed large effects on identifying AD status with Cohen's d = 0.81 (95%CI 0.44-1.18). LOESS regression illustrated that plasma GFAP increased from the early stages of AD. Plasma GFAP has potential applications across diverse populations.

Extracellular vesicles (EVs) represent a diverse class of nanoscale membrane vesicles actively released by cells. These EVs can be further subdivided into categories like exosomes and microvesicles, based on their origins, sizes, and physical attributes. Significantly, disease-derived EVs have been detected in virtually all types of body fluids, providing a comprehensive molecular profile of their cellular origins. As a result, EVs are emerging as a valuable addition to liquid biopsy techniques. In this collective statement, the authors share their current perspectives on EV-related research and product development, with a shared commitment to translating this newfound knowledge into clinical applications for cancer and other diseases, particularly as disease biomarkers. The consensus within this document revolves around the overarching recognition of the merits, unresolved questions, and existing challenges surrounding EVs. This consensus manuscript is a collaborative effort led by the Committee of Exosomes, Society of Tumor Markers, Chinese anti-Cancer Association, aimed at expediting the cultivation of robust scientific and clinically applicable breakthroughs and propelling the field forward with greater swiftness and efficacy.

Cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) are reliable predictors of future AD risk. We investigated whether pre-clinical changes in AD CSF biomarkers are reflected in blood DNA methylation (DNAm) levels in cognitively normal participants.

We profiled blood-based DNAm with the EPIC array in participants without a diagnosis of cognitive impairment in the Emory Healthy Brain Study (EHBS; N=495) and ADNI (N=122). Their CSF Aβ42, tTau, and pTau levels were quantified using Elecsys immunoassays. We conducted epigenome-wide association studies to assess associations between DNAm and CSF biomarkers of AD.

In EHBS, no loci were Bonferroni-significant after adjusting for confounding factors. In ADNI, two loci were significant, but they were not replicated in EHBS. There was little agreement between the top loci from EHBS and ADNI.

Our study showed little evidence of an association between differential blood-based DNAm and pre-clinical AD CSF biomarkers.

Systemic inflammation with alterations in inflammatory markers is involved in ageing and Alzheimer's disease. However, few studies have investigated the longitudinal trajectories of systemic inflammatory markers during ageing and Alzheimer's disease, and specific markers contributing to Alzheimer's disease remain undetermined. In this study, a longitudinal cohort (cohort 1: n = 290; controls, 136; preclinical Alzheimer's disease, 154) and a cross-sectional cohort (cohort 2: n = 351; controls, 62; Alzheimer's disease, 63; vascular dementia, 58; Parkinson's disease dementia, 56; behavioural variant frontotemporal dementia, 57; dementia with Lewy bodies, 55) were included. Plasma levels of inflammatory markers were measured every 2 years during a 10-year follow-up in the longitudinal cohort and once in the cross-sectional cohort. The study demonstrated that the inflammatory markers significantly altered during both ageing and the development of Alzheimer's disease. However, only complement C3, interleukin-1β and interleukin-6 exhibited significant changes in participants with preclinical Alzheimer's disease, and their longitudinal changes were significantly associated with the development of Alzheimer's disease compared to controls over the 10-year follow-up. In the cross-sectional cohort, complement C3 demonstrated specificity to Alzheimer's disease, while interleukin-1β and interleukin-6 were also altered in other dementias. The study provides a new perspective on the involvement of inflammatory markers in the ageing process and the development of Alzheimer's disease, implying that regulating inflammation may have a pivotal role in promoting successful ageing and in the prevention and treatment of Alzheimer's disease.

Neurosyphilis (NS) is a clinical condition caused by infection of the central nervous system (CNS) by Treponema pallidum (Tp) that can lead to asymptomatic meningitis and more serious neurological diseases, such as dementia and blindness. However, current studies on the pathogenesis of NS are limited. Here, through the integration analysis of proteomics and single-cell transcriptomics, Toll-like/NF-κB signaling is identified as the key pathway involved in CNS damage caused by Tp. Moreover, monocyte-derived macrophages are key cells involved in the inflammatory response to Tp in the CNS of NS patients. In addition, it is found that inflammatory cells in peripheral blood may cause neurological damage through disruption of the blood‒brain barrier (BBB) in individuals with NS. Notably, activation of the Toll-like/NF-κB signaling pathway, as well as dysregulation of neural function, is likewise validated in an in vitro NS brain organoid model. In conclusion, the results revealed the mechanisms of inflammation-mediated brain injury in Tp-induced NS and provided new ideas for the clinical treatment of Tp infection.

Prognostic biomarkers at multiple sclerosis (MS) onset to predict disease severity may help guide initial therapy selection for people with MS. Over 20 disease-modifying treatments (DMTs) of varying levels of risk and efficacy now exist. The ability to predict MS severity would help to identify those patients at higher risk where a highly effective, but potentially risky, therapy would be optimal. The goal of this project was to determine if cerebrospinal fluid (CSF) soluble markers obtained near time of diagnosis can predict disease severity in people with relapsing remitting MS (RRMS).

We identified 42 RRMS subjects with 4 or more years of clinical follow-up at our center, 8 subjects with other inflammatory neurological diseases (OIND), and 4 subjects with non-inflammatory neurological diseases (NIND) who had donated CSF samples collected for disease diagnosis. This study evaluated soluble CSF biomarkers chosen to reflect neuroinflammation (chemokine ligand 13 - CXCL13), microglia activity (soluble triggering receptor expressed on myeloid cells 2 - sTREM2), demyelination (myelin basic protein -MBP), axon injury and loss (neurofilament light, heavy, and intermediate chains - NFL, NFH, internexin-alpha - INT-α) and neuronal loss (parvalbumin - PVALB) to determine whether any of these CSF factors might predict future MS disease severity. The main outcome measure was MS Severity Score (MSSS), which takes into account disability accumulation (expanded disability status scale - EDSS) and duration of disease. EDSS at last clinical visit was a secondary outcome measure. Univariate and multivariable regression models were used for analysis. Spearman correlations were performed to evaluate correlation between laboratory and clinical variables.

Forty-two RRMS patients with mean 9.4 years follow-up since lumbar puncture (LP) contributed data. Higher NFH, NFL, and sTREM2 each predicted worse MSSS using both univariate and multivariable regression models. Older age at the time of LP predicted worse MSSS both in the univariate and multivariable models. NFL correlated with NFH, and both were positively correlated with sTREM2 and CXCL13. In the combined OIND and NIND comparator group, NFH correlated with both NFL and CXCL13.

These data support that CSF sTREM2, NFH, and NFL are predictors of MSSS, a measure of MS disease aggressiveness. This study adds to a growing literature implicating microglial activity and axonal injury in MS progression, starting from early stages of the disease.

Recently, proteinogenic amino acids have become very interesting molecules, accompanied by a large variety of metabolic processes in humans and are associated with various diseases. In the era of system biology, including a broad spectrum of associated disciplines (e.g., metabolomics, lipidomics, proteomics, etc.), the possibility of identifying trustworthy biomarkers of diseases becomes much more likely. Changes in amino acid levels in plasma, serum, or cerebrospinal fluid reflect physiological or pathological conditions and, therefore, their regular monitoring can lead to early detection of the occurrence of a disease. Therefore, the exact determination of amino acids in biological fluids is of great importance. However, it is necessary to dispose with an effective, accurate, precise, selective, and robust analytical method. This protocol describes the complex procedure of amino acid analysis based on a combination of UHPLC with single quadrupole MS. The protocol presents a highly reproducible and robust methodology that has already been established in the quality control of biopharmaceuticals and determination of proteinogenic amino acids in urine in our laboratory. Here, the application potential is extended to the most frequently investigated biological fluid, that is, plasma and to the cerebrospinal fluid, which is investigated in many neurological conditions.

People with Down Syndrome (DS) are at high risk of developing Alzheimer's disease dementia (AD) and cerebral amyloid angiopathy, which is a critical factor contributing to dementia in sporadic AD. Predicting and monitoring the decline and onset of dementia is a diagnostic challenge and of essence in daily care and support for people with DS. In this literature scoping review, we first summarize the different blood-based biomarkers for AD in DS. Next, we describe urine-based biomarkers for AD in DS and finally, we explore various blood-based biomarkers in the general AD population. Apart from the classic amyloid beta and Tau biomarkers, we also discuss more out-of-the-box biomarkers such as neurofilament light chain, Dual-specificity tyrosine-regulated kinase 1A, and monoaminergic biomarkers. These potential biomarkers could be a valuable addition to the established panel of fluid biomarkers.

Different forms of phosphorylated tau (p-tau) have shown strong potential as Alzheimer's disease (AD) biomarkers in both cerebrospinal fluid (CSF) and plasma. We hypothesized that p-tau proteoforms simultaneously phosphorylated at two different sites may have an increased diagnostic value compared with tau phosphorylated at a single site. Here, we developed two immunoassays detecting CSF and plasma tau simultaneously phosphorylated at both T181 and T231 (p-tau181&231) and at T217 and T231 (p-tau217&231). Subsequently, we measured CSF and plasma p-tau181&231, p-tau217&231, p-tau181, p-tau217, and p-tau231 levels in two cohorts across the AD continuum and in frontotemporal dementia (FTD) patients (discovery n = 55, validation n = 118). CSF and plasma p-tau217&231, p-tau181, p-tau217, and p-tau231 and CSF, but not plasma, p-tau181&231 were significantly elevated in all AD continuum groups vs. Neurological Disease Control group. Notably, plasma p-tau217&231 consistently showed an improved diagnostic performance compared with single-site phosphorylation assays - p-tau217 or p-tau231. The differences observed between CSF and plasma measurements suggest matrix-specific protein processing, underscoring the need for further research on the dynamics of tau phosphorylation pattern along the AD continuum.

MicroRNAs (miRNAs) are regulators of gene expression and have been reported to be dysregulated in people with multiple sclerosis (pwMS). Autologous hematopoietic stem cell transplantation (aHSCT) is an immune-ablative treatment intervention for pwMS. Currently, it is unknown if aHSCT affects expression levels of miRNAs in CSF. We explored the ability of circulating miRNA to discriminate between pwMS and healthy controls (HCs) and investigated whether these miRNAs were affected by treatment with aHSCT.

Using quantitative reverse transcription PCR, 87 miRNAs were analyzed in CSF samples of a discovery cohort (baseline: 4 & HC: 4). The top 22 miRNAs discriminating between pwMS and HCs were then analyzed in 187 CSF samples of a validation cohort (pwMS: 50, HC: 32). Samples, failing quality control or being follow-ups to baseline samples with quality control issues, were excluded from further analyses. The remaining 133 samples (HC: 29, MS: baseline: 33, 1 year: 30, 2 years: 26, 3-5 years: 15) were analyzed for expression of the top 22 miRNAs.

Twelve miRNAs were dysregulated in pwMS compared with HC (q < 0.05). Associations with clinical and analytical parameters were observed in relation to all 12 miRNAs; however, a cluster of 4 miRNAs (miR-16-5p, miR-21-5p, miR-150-5p, and miR-146a-5p) with strong correlations (r > 0.60, p < 0.001) with multiple parameters was identified. Of the 12 miRNAs, 8 were differentially expressed in pwMS with gadolinium-enhancing lesions at baseline and 4 by prior disease-modifying treatment class (p < 0.05). These 4 miRNAs correlated strongly with each other, decreased after aHSCT, and remained low throughout the follow-up period (p < 0.05). Target and pathway analysis of these revealed association with biological processes affecting cytokine production, inflammatory response, and regulation of myelin maintenance.

miRNAs are dysregulated in CSF from pwMS and particularly in patients with less effective treatments and/or higher inflammatory disease activity. A 4-miRNA signature with elevated expression of miR-16-5p, miR-21-5p, miR-150-5p, and miR-146a-5p was recurring in multiple analyses. After intervention with aHSCT, the expression levels approached the levels of the HCs, suggesting a potent treatment effect.

Multiple sclerosis (MS) can start as relapsing or progressive. While their clinical features and treatment responses are distinct, it has remained uncertain whether their pathomechanisms differ. A notable age-related effect on MS phenotype and response to immunotherapies is well acknowledged, but the underlying pathophysiologic reasons are yet to be fully elucidated. We aimed to identify disease-specific and age-related proteomic signatures using a comprehensive targeted proteomic analysis.

In our retrospective cohort study, we analyzed the CSF and serum proteome of age-matched individuals with treatment-naïve relapsing-remitting and primary progressive MS, neurologic controls (NC), and individuals with neuroborreliosis using targeted proteomics and validated findings in an independent cohort. Proteomic results were integrated with clinical and laboratory covariates.

Among 2,500 proteins, 47 CSF proteins were distinct between individuals with MS (n = 60) and NC (n = 20), with a subset also differing from those with neuroborreliosis (n = 8). We identified MS-associated proteins, including novel candidate biomarkers such as LY9 and JCHAIN, and putative treatment targets, such as SLAMF7, BCMA, and IL5RA, for which drugs are already licensed in other indications. The CSF proteome differences between relapsing and progressive MS were minimal, but major changes were noted in individuals older than 50 years, indicating a shift from MS-associated inflammatory to age-related protein signature. NEFL was the only serum protein that differed between individuals with MS and controls.

This study unveils a unique CSF proteomic signature in MS, providing new pathophysiologic insights and identifying novel biomarker candidates and potential therapeutic targets. Our findings highlight similar immunologic mechanisms in relapsing and progressive MS and underscore aging's profound effect on the intrathecal immune response. This aligns with the observed lower efficacy of immunotherapies in the elderly, thus emphasizing the necessity for alternative therapeutic approaches in treating individuals with MS beyond the age of 50.

In patients with myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), acute disease activity is generally identified through medical history, neurologic examination, and imaging. However, these may be insufficient for detecting disease activity in specific conditions. This study aimed to investigate the dynamics of serum neurofilament light chain (sNfL) and serum glial fibrillary acidic protein (sGFAP) after clinical attacks and to assess their utility in discriminating attacks from remission in patients with MOGAD.

We conducted a multicenter, retrospective, longitudinal study including 239 sera from 62 MOGAD patients assessed from 1995 to 2023 in a discovery and validation setup. Sera were measured for sNfL and sGFAP with a single-molecule array assay and for MOG-IgG with a live cell-based assay. sNfL and sGFAP Z scores and percentiles adjusted for age, body mass index, and sex (sGFAP) were calculated from a healthy control normative database. Mixed-effects regression models were used to characterize biomarkers' dynamics and to investigate associations between serum biomarkers, clinical variables, and disease activity status.

Among the 62 study participants, 29 (46.8%) were female, with a median age at baseline of 40.0 years (interquartile range [IQR] 29.5-49.8) and a median duration of follow-up of 20.0 months (IQR 3.0-62.8). sNfL and sGFAP Z scores were nonlinearly associated with time from attack onset (p < 0.001 and = 0.002, respectively). During attacks, both biomarkers presented higher median values (sNfL Z score 2.9 [IQR 1.4-3.5], 99.8th; sGFAP Z score 0.4 [IQR -0.5 to 1.5], 65.5th) compared with remission (sNfL Z score 0.9 [IQR -0.1 to 1.6], 81.6th, p < 0.001; sGFAP Z score -0.2 [IQR -0.8 to 0.5], 42.1th; p < 0.001) across all clinical phenotypes. sNfL values consistently discriminated disease activity status in the discovery and validation cohorts, showing a 3.5-fold increase in the odds of attacks per Z score unit (odds ratio 3.5, 95% confidence interval 2.3-5.1; p < 0.001). Logistic models incorporating sNfL Z scores demonstrated favorable performance in discriminating disease activity status across both cohorts.

sNfL Z scores may serve as a biomarker for monitoring disease activity in MOGAD.

The enzyme-linked immunosorbent assay (ELISA) is commonly used in research and diagnostics but has limitations, including its single-substance detection and large sample volume requirements. In contrast, the Luminex technique, a bead-based sandwich immunoassay combined with flow cytometry, overcomes these limitations by simultaneous measurement of multiple analytes in small volumes. Using dyed micro-beads coated with monoclonal antibodies, this method can detect 100-500 immune markers in cerebrospinal fluid, capturing multiple targets from a single sample. This chapter discusses key pre-analytical factors like sample collection and preservation that influence detection outcomes, highlighting the Luminex technique's adaptability for measuring diverse biomarkers and its advantages in diagnostic applications, reducing variability, and optimizing resources.

Despite the progress in understanding the pathogenesis of diffuse brainstem tumors, treatment of these neoplasms is usually empirical and conducted without morphological and molecular verification. Liquid biopsy is a minimally invasive technique providing data on tumor biology without standard biopsy. This method is based on analysis of cell-free nucleic acids (predominantly, extracellular DNA) in biological fluids with detection of specific mutations. Despite wide implementation in diagnosis and disease monitoring in extracranial malignancies, it is infrequently applied in neuro-oncology.

To estimate diagnostic value of liquid biopsy in detecting H3K27 and BRAF V600E mutations in patients with diffuse brainstem tumors.

Lumbar puncture with cerebrospinal fluid sampling was performed in 16 patients (5 children and 11 adults) with diffuse brainstem tumors verified by neuroimaging data. Cell-free DNA (cfDNA) was used in digital droplet PCR for determination of H3F3A K28M and BRAF V600E oncogenic missense variants. In 14 patients, investigation of cfDNA was performed in parallel with analysis of correspondent mutations in DNA derived from tumor tissue.

None patient had BRAF V600E mutation. H3F3A K28M variant was detected in 5 CSF samples and 6 tumor specimens from patients who underwent surgical biopsy. Thus, overall sensitivity of the method in determination of H3F3A K28M variant was 92.9% (13/14).

Liquid biopsy is highly informative for identifying the specific mutation H3F3A K28M and often verifies diffuse brainstem glioma without standard biopsy.

People with multiple sclerosis (PwMS) experience various degrees of cognitive impairment (CI). Synaptic dysfunction may contribute to CI in PwMS but cerebrospinal fluid (CSF) synaptic biomarkers are unexplored in MS.

To assess the role of CSF synaptosomal-associated protein 25 (SNAP-25), β-synuclein, neurogranin and neurofilament light chain protein (NfL) in patients with early relapsing MS with and without CI.

We measured CSF SNAP-25, β-synuclein, and neurogranin in 48 untreated PwMS and 50 controls with other neurological diseases (ONDs) and tested their associations with neuropsychological and MRI data.

CSF synaptic protein levels did not discriminate between MS subjects and patients with ONDs, with only SNAP-25 values being slightly increased in MS (p = 0.009). CSF synaptic markers were positively correlated with each other and with CSF NfL. Moreover, lower biomarker levels were found to be correlated with longer disease duration and lower brain volumes (especially of the thalamus). Moreover, we found significantly lower CSF SNAP-25 (p = 0.025), β-synuclein (p = 0.044), and neurogranin (p = 0.007) levels in PwMS with vs. without domain-specific cognitive impairment.

Lower CSF synaptic biomarker levels were found in PwMS with longer disease duration and lower brain volumes and may identify PwMS at risk of CI.

The Gas6/TAM (Tyro3, Axl, and Mer) receptor system has been implicated in demyelination and delayed remyelination in experimental animal models, but data in humans are scarce. We aimed to investigate the role of Gas6/TAM in neurodegenerative processes in multiple sclerosis (MS).

From a prospective 5-year follow-up study, soluble Gas6/TAM biomarkers were analyzed in cerebrospinal fluid (CSF) by enzyme-linked immunosorbent assay (ELISA) at baseline in patients with relapsing-remitting MS (RRMS) (n = 40), progressive MS (PMS) (n = 20), and healthy controls (HC) (n = 25). Brain volumes, including myelin content (MyC) and white matter (WM) were measured by synthetic magnetic resonance imaging at baseline, 12 months, and 60-month follow-up. Associations with brain volume changes were investigated in multivariable linear regression models. Gas6/TAM concentrations were also determined at 12 months follow-up in RRMS to assess treatment response.

Baseline concentrations of Tyro3, Axl, and Gas6 were significantly higher in PMS vs. RRMS and HC. Mer was higher in PMS vs. HC. Tyro3 and Gas6 were associated with reduced WM (β = 25.5, 95% confidence interval [CI] [6.11-44.96, p = 0.012; β = 11.4, 95% CI [0.42-22.4], p = 0.042, respectively) and MyC (β = 7.95, 95%CI [1.84-14.07], p = 0.012; β = 4.4, 95%CI [1.04-7.75], p = 0.012 respectively) at 60 months. Patients with evidence of remyelination at last follow-up had lower baseline soluble Tyro3 (p = 0.033) and Gas6 (p = 0.014). Except Mer, Gas6/TAM concentrations did not change with treatment in RRMS.

Our data indicate a potential role for the Gas6/TAM receptor system in neurodegenerative processes influencing demyelination and ineffective remyelination.

It is well known that myelin disruption and neuroinflammation are early and distinct pathological hallmarks in multiple system atrophy (MSA) as well as in idiopathic Parkinson's disease and in other atypical Parkinsonian syndromes. The objective of this study was to assess the value of non-neuronal biomarker candidates that reflect myelin disruption and neuroinflammation.

Myelin basic protein (MBP) and the soluble form of TREM2 were quantified in a comprehensive movement disorder cohort from two different neurological centers, comprising a total of 171 CSF samples. Commercially available ELISA systems were employed for quantification.

The results of the MBP analysis revealed a significant increase in cerebrospinal fluid (CSF) MBP levels in all atypical Parkinsonian conditions compared to PD. This differentiation was more pronounced in the MSA-c subtype compared to MSA-p. Receiver operating characteristic (ROC) analysis revealed a significant discrimination between PD and MSA (p = 0.032, AUC = 0.70), PD and DLB (p = 0.006, AUC = 0.79) and PD and tauopathies (p = 0.006, AUC = 0.74). The results of the TREM2 analysis demonstrated no significant differences between the PD and atypical Parkinsonian groups if not adjusted for confounders. After adjusting for age, sex, and disease duration, the PD group exhibited significantly higher TREM2 levels compared to the DLB group (p = 0.002).

In conclusion, MBP, but not TREM2, is elevated in the CSF of not only MSA but in all atypical Parkinsonian conditions compared to idiopathic Parkinson's disease. This highlights the value of the evaluation of myelin/oligodendrocyte-associated markers in neurodegenerative movement disorders.