ID: 40325332
Title: Neuron-Derived Extracellular Vesicles: Emerging Regulators in Central Nervous System Disease Progression.
Abstract: The diagnosis and exploration of central nervous system (CNS) diseases remain challenging due to the blood-brain barrier (BBB), complex signaling pathways, and heterogeneous clinical manifestations. Neurons, as the core functional units of the CNS, play a pivotal role in CNS disease progression. Extracellular vesicles (EVs), capable of crossing the BBB, facilitate intercellular and cell-extracellular matrix (ECM) communication, making neuron-derived extracellular vesicles (NDEVs) a focal point of research. Recent studies reveal that NDEVs, carrying various bioactive substances, can exert either pathogenic or protective effects in numerous CNS diseases. Additionally, NDEVs show significant potential as biomarkers for CNS diseases. This review summarizes the emerging roles of NDEVs in CNS diseases, including Alzheimer's disease, depression, traumatic brain injury, schizophrenia, ischemic stroke, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. It aims to provide a novel perspective on developing therapeutic and diagnostic strategies for CNS diseases through the study of NDEVs.

ID: 41140053
Title: Diagnostic and Prognostic Value of Blood and Cerebrospinal Fluid Biomarkers in Amyotrophic Lateral Sclerosis: A Systematic Review and Meta-Analysis.
Abstract: Reliable biomarkers for amyotrophic lateral sclerosis (ALS) are urgently needed due to diagnostic and prognostic challenges. This systematic review and meta-analysis aimed to synthesize recent evidence on the utility of blood and cerebrospinal fluid (CSF) biomarkers for ALS. We systematically reviewed studies published from January 1, 2019 to March 25, 2025, that evaluated blood or CSF biomarkers for ALS. Eligible studies reported diagnostic performance, group-level biomarker values, hazard ratios (HRs) for survival, or correlations with functional rating scales or disease progression rates. Study quality was assessed using the QUADAS-2 and QUIPS frameworks. Random-effects models were employed to pool summary receiver operating characteristic (SROC) curves, HRs, standardized mean differences, and correlation coefficients. We included 47 studies in the SROC analysis and 27 in the HR analysis, covering 9078 participants (5556 ALS and 3522 controls). Neurofilament light chain (NfL) consistently demonstrated the highest diagnostic accuracy (sensitivity/specificity: 0.81-0.87 vs. ALS mimics) and high prognostic value (pooled HRs: 2.8-4.3) in both blood and CSF. CSF chitinases and the p-tau/t-tau ratio showed moderate utility. Other biomarkers, including interleukins, had limited clinical relevance. Most studies showed moderate to high risk of bias, with methodological heterogeneity and limited transparency. NfL is the most validated biomarker for ALS diagnosis and prognosis, in both blood and CSF. However, its limited accuracy when used alone carries a considerable risk of misclassification. Future studies should adopt prevalence-specific strategies and integrate biomarkers within multimodal frameworks to enhance diagnostic and prognostic precision.

ID: 41147537
Title: Multiple Antibody-Coated Gold Nanoparticle-Based ExoAssay for Rapid Isolation of CNS-Specific Exosomes From Blood.
Abstract: In neurodegenerative diseases, brain-derived extracellular vesicles (EVs)/exosomes from blood offer a great opportunity to explore their contents for their utility as biomarkers. However, the conventional methodologies for the purification of EVs from complex biofluids have many limitations, restricting their clinical implementation. We aimed to optimize a direct, less time-consuming, affordable, and reliable nanowire-based method to isolate neuronal EVs from blood plasma. Here, we improved a simple and direct methodology using multiple antibody-coated magnetic nanowires for efficient and rapid isolation of neuronal EVs (ExoAssay) from human plasma. We characterized the isolated EVs and validated the protocol using multiple approaches, for example, nanoparticle tracking analysis (NTA), immunoblotting, and transmission electron microscopy (TEM). We purified round-shaped EVs with an average size of 116 nm. We identified the general markers of EVs including CD9, CD63, CD81, and Flotillin-1 and two neuronal EV markers L1-cell adhesion molecule (L1CAM) and neural cell adhesion molecule (NCAM) via immunoblotting. Interestingly, the levels of T-Tau and P-Tau were upregulated in EVs isolated from Alzheimer's patients (n = 30), in comparison with healthy controls. Furthermore, there were no significant differences between CSF- and EV-based Tau levels. The high-throughput mass-spectrometry analysis of isolated EVs revealed 280 proteins as significantly modified in Alzheimer's disease cases in comparison with controls. The presented nanotechnology-based methodology offers an innovative and efficient tool for EV-based biomarker investigations and clinical utility by simplifying the enrichment of CNS-originated exosomes from complex biological fluids. This methodology opens up the avenue for longitudinal monitoring of important disease-related proteins in the brain by analysis of brain-derived EVs from blood plasma using simple blood withdrawal.

ID: 41641858
Title: Hypoxia stimulates blood-brain barrier disruption and systemic appearance of pro-coagulant, brain-derived extracellular vesicles: Implications in transient ischemic attack patients.
Abstract: Tissue hypoxia and blood-brain barrier (BBB) dysfunction are key features of transient ischaemic attack (TIA) and ischaemic stroke. The neurovascular unit maintains brain homeostasis and coordinates stress responses. Extracellular vesicles (EVs) are emerging as important mediators of cell communication in hypoxia, impacting BBB integrity and enabling bidirectional movement. This study examined EV production by neurovascular cells in normoxia (21% O2) and hypoxia (1% O2) and compared these profiles with circulating EVs in TIA patients. Human brain endothelial cells and astrocytes were cultured under normoxic or hypoxic conditions for up to 24 h. EVs were isolated and analysed via nanoparticle tracking and flow cytometry. A co-culture transwell model assessed BBB permeability under controlled experimental conditions. Circulating EVs from TIA patients, TIA mimics and healthy controls were analysed for cell origin, phenotype and function. Hypoxia increased EV production from endothelial cells, disrupted BBB integrity and promoted EV movement across the barrier. TIA patients had distinct EV profiles, with elevated endothelial-derived (CD9+/CD144+) and astrocyte-derived (CD9+/GFAP+) EVs and proteins. Both cell- and patient-derived EVs enhanced clot formation and resistance to lysis. These findings suggest EVs contribute to post-TIA thrombotic risk. Astrocyte-derived EVs may serve as rapid, cost-effective biomarkers to distinguish TIA from mimics.

ID: 41850233
Title: Identification of tofersen PD-response biomarkers in VALOR clinical trial CSF via multiplexed quantitative proteomics.
Abstract: Tofersen, the first approved genetically targeted therapy for amyotrophic lateral sclerosis (ALS), demonstrates significant lowering of plasma neurofilament in adults carrying mutations in the superoxide dismutase 1 (SOD1) gene; however, additional biomarkers of treatment response in ALS are lacking. Here, we analyze longitudinally collected cerebrospinal fluid (CSF) samples from the phase 3 VALOR clinical trial to identify candidate tofersen treatment-response biomarkers in SOD1-ALS via quantitative proteomics. We observe significant modulation from baseline abundance for 56 proteins in tofersen-treated participants relative to placebo, including CSF GPNMB, which is significantly and continuously elevated across all post-baseline timepoints. We orthogonally confirm this observation by GPNMB immunoassay in independent tofersen-treated cohorts. Taken together, these data identify pharmacodynamic-response biomarkers of tofersen treatment that can be measured as early as 4 weeks post-treatment in SOD1-ALS patients and demonstrate the utility of leveraging unbiased proteomic screening integrated with targeted validation methods to identify pharmacodynamic-response biomarkers in clinical trial patient samples.

ID: 42196191
Title: Longitudinal CSF and Serum Biomarker Dynamics in Tofersen-Treated SOD1-ALS: A Real-World Multicentre Cohort Study.
Abstract: Tofersen is a gene-targeted therapy for superoxide dismutase 1 (SOD1)-associated amyotrophic lateral sclerosis (ALS), but neurofilament light chain (NfL) may not fully capture the biological response to treatment. We performed a multicentre retrospective longitudinal study including 24 patients with SOD1-ALS treated with intrathecal tofersen at four Italian referral centres between 2022 and 2025. Cerebrospinal fluid (CSF) and serum biomarkers were assessed at baseline, month 3, month 6, and last available administration using single-molecule array assays to quantify NfL, glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase L1 (UCHL-1), and total Tau. NfL decreased after treatment initiation in both CSF and serum, providing the clearest pharmacodynamic signal. In contrast, CSF GFAP increased progressively over follow-up, while CSF total Tau and UCHL-1 rose mainly at later timepoints; serum GFAP, total Tau, and UCHL-1 also showed increases during follow-up. ALS Functional Rating Scale-Revised trajectories were broadly stable, whereas disease progression rate was lower at last follow-up than at baseline. Greater reductions in CSF NfL were observed in pathogenic versus uncertain SOD1 variants, and early serum NfL and UCHL-1 changes were associated with longer-term changes in disease progression. These findings suggest that longitudinal multi-analyte profiling may refine biological response stratification beyond NfL alone in tofersen-treated SOD1-ALS.

ID: 42217760
Title: Fluid-based biomarkers of amyotrophic lateral sclerosis: recent advances and future prospects.
Abstract: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder with no definitive cure. The absence of specific diagnostic biomarkers leads to diagnostic delays, hindering early intervention and management. This review provides a critical appraisal of fluid-based biomarkers for ALS across multiple sources-cerebrospinal fluid (CSF), blood, urine, saliva, and tears-with emphasis on their diagnostic and prognostic potential, limitations, and readiness for clinical translation. While neurofilaments (NfL, pNfH) are well-established as sensitive indicators of neuroaxonal injury and are increasingly used as prognostic and pharmacodynamic markers in clinical trials, they lack disease specificity. Biomarkers reflecting ALS-specific pathology, such as TDP-43 species and C9orf72 dipeptide repeat proteins (DPRs), show promise but remain in early validation stages with limited multicenter data. Emerging markers from non-invasive sources (urine p75ECD, salivary chromogranin A, tear metabolomics) offer potential for repeated sampling but require rigorous external validation before clinical adoption. To address current gaps, we introduce a standardized evidence grading framework (Tier 1-3) and a comprehensive reporting template for biomarker studies, including explicit performance metrics (AUC, sensitivity, specificity, confidence intervals) and validation status. We also propose minimum reporting standards for study design, pre-analytical variables, and statistical rigor, modeled on REMARK guidelines. A roadmap for biomarker validation and a cross-fluid comparison matrix are provided to guide future research. Despite considerable progress, significant challenges remain, including biological heterogeneity, pre-analytical variability, and insufficient external validation. Future efforts should prioritize multicenter prospective studies, assay harmonization, ethical frameworks for early diagnosis, and integration of emerging technologies such as artificial intelligence and digital twins. Fluid-based biomarkers, while not yet replacing clinical evaluation, are essential tools for accelerating drug development, enabling patient stratification, and moving toward personalized medicine in ALS.

ID: 42251967
Title: PBMC DEG/miRNA biomarkers of TDP-43 pathology in ALS.
Abstract: Amyotrophic lateral sclerosis (ALS) lacks reliable, disease-specific, and minimally invasive biomarkers, representing a major barrier to early diagnosis and patient stratification. The primary aim of this translational pilot study was to identify a disease-specific, TDP-43-related, gene-microRNA (miRNA) signature in peripheral blood mononuclear cells (PBMCs) of ALS patients with potential diagnostic value. To this end, we first identified differentially expressed disease-specific genes (dsDEGs) using a TDP-43-based rat model of ALS, generated by stereotaxic infusion of full-length (FL) TAR DNA-binding protein 43 (TDP-43) into the motor cortex. Transcriptomic profiling of the motor cortex revealed candidate dsDEGs, which were subsequently validated by RT-qPCR in motor cortex, spinal cord, and PBMCs from the same animals. To assess translational relevance, expression levels of these dsDEGs were analyzed in PBMCs from early- to mid-stage ALS patients and matched healthy controls, while disease specificity was evaluated using Parkinson's disease (PD) samples. In parallel, conserved miRNAs predicted to target the identified dsDEGs were examined in both rat and human PBMCs. Five dsDEGs, Mctp1, Penk, Mt2A, Drd1, and Rasgrp2, were consistently dysregulated across central and peripheral tissues in the TDP-43 rat model. RT-qPCR analysis of human PBMCs confirmed significant and selective dysregulation of these genes in ALS, but not in PD, supporting disease specificity. Moreover, exposure of human neuroblastoma cells and healthy PBMCs to TDP-43 recapitulated the ALS-like expression changes. Computational and experimental analyses identified seven conserved miRNAs targeting these dsDEGs, of which four were significantly downregulated in ALS PBMCs, supporting a coordinated regulatory network. Receiver operating characteristic (ROC) analyses demonstrated strong discriminative performance for both the gene signature (AUC 0.87-1.00) and the associated miRNAs (AUC 0.95-1.00). Together, these findings define a novel PBMC-based gene-miRNA signature that mirrors central ALS pathology and shows high diagnostic accuracy and disease specificity, highlighting its potential as a minimally invasive biomarker for ALS.

ID: 42363684
Title: FMRP-Mediated Proteasome Regulation: A Novel Mechanism in ALS Pathology.
Abstract: Amyotrophic Lateral Sclerosis (ALS) is a rare and fatal neurodegenerative disease characterized by the hallmark cytoplasmic accumulation and aggregation of TAR DNA binding protein 43 (TDP-43), which impairs proteasome activity through its interaction with Tankyrase (TNKS). Using molecular and imaging techniques, we have identified a novel role for the Fragile X Mental Retardation Protein (FMRP) in regulating the TNKS/PI31-mediated proteasome activation mechanism in co-operation with TDP-43. Our results demonstrate that depletion of FMRP causes nuclear translocation of TDP-43, reducing cytoplasmic TNKS/TDP-43 co-localization, thereby releasing TNKS in the cytoplasm. Free TNKS gets associated with proteasome inhibitor of 31 kDa (PI31), reversing PI31-mediated inhibition of proteasome assembly, trafficking, and activity. Thus, FMRP regulates proteasome activity by modulating the subcellular distribution of TDP-43. Interestingly, FMRP expression is elevated in specific brain regions and spinal cords of TDP-43A315T transgenic ALS mice that helps more TDP-43 to stay in cytoplasm to sequester more TNKS with it, resulting in proteasome dysfunction in ALS disease system. We have demonstrated for the first time that FMRP can act as a disease modifier for ALS. ALS patients with high FMRP expression in the brain and spinal cord may exhibit more severe protein aggregation due to proteasome dysfunction.

ID: 42372734
Title: An open-label Phase 2a study of fasudil in amyotrophic lateral sclerosis: safety and exploratory endpoints.
Abstract: The primary objective was to assess the safety of oral fasudil in amyotrophic lateral sclerosis (ALS) patients. Changes in serum neurofilament light (NfL) levels and the ratio of phosphorylated to total AKT (pAKT/tAKT) were exploratory endpoints. This was a multicenter, open-label study. Two 31-patient cohorts were sequentially enrolled and treated with either 180 mg or 300 mg per day of oral fasudil for 24 weeks. The primary endpoint was safety. Secondary endpoints evaluated changes in the ALS functional rating scale-revised (ALSFRS-R), slow vital capacity, and muscle strength. We also assessed changes in serum NfL and pAKT/tAKT ratios in plasma (neuron-derived) and CSF (total) extracellular vesicles (EVs). Eighty-one percent (25/31) and 71% (22/31) of patients completed 24 weeks of treatment in the 180 and 300 mg cohort, respectively. Fasudil was safe and well tolerated, with predominantly mild drug-related adverse events. Secondary endpoints, though not statistically significant, were directionally consistent with a treatment effect. Exploratory analyses showed a 15.4% reduction in serum NfL at 24 weeks (p = 0.001) in the 180 mg cohort, with no change in the 300 mg cohort (-0.4%, p = 0.990). The NfL reduction was inversely correlated with ALSFRS-R decline (Spearman = -0.45, p = 0.028). Ratios of pAKT/tAKT, a pharmacodynamic marker of rho kinase (ROCK) inhibition, were significantly increased at 24 weeks in plasma (neuron-derived) and CSF EVs. Oral fasudil is safe and well-tolerated in ALS patients. The reduction in NfL and demonstration of CNS target engagement, supports studying the 180 mg dose in a double-blind placebo-controlled study.

ID: 42383305
Title: TDP-43 proteinopathy as a biomarker and therapeutic target in amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis (ALS) is the most common form of adult-onset motor neuron disease, characterised by the degeneration of upper and lower motor neurons. The cytoplasmic aggregation of TDP-43 (TAR DNA-binding protein 43), an RNA-binding protein, is considered a hallmark of ALS pathology, found in nearly all postmortem cases of ALS. TDP-43 is normally primarily nuclear, where it has a widespread role in gene regulation. Mutations, extrinsic stressors, and alterations in RNA homeostasis in ALS lead to nuclear depletion of TDP-43 and the formation of cytosolic TDP-43 aggregates. This causes multiple downstream effects on neuronal function and degeneration as well as gene expression. TDP-43 is a promising target as a biomarker, as it is found to be elevated in the biofluids of ALS patients, and its cytoplasmic aggregation can also be observed in peripheral tissues; however, methodological variability and technical limitations currently preclude the establishment of TDP-43 as a standalone biomarker. There are also promising therapeutic strategies in development targeting TDP-43 pathology, but a critical challenge that remains is achieving a balance between eliminating toxic aggregates and preserving the essential functions of TDP-43. In summary, with further research, considering TDP-43 pathology in ALS gives hope for finding future novel diagnostics and therapeutics for ALS.

ID: 42396333
Title: The Target ALS Global Natural History Study: Cross-platform proteomics to accelerate biofluid biomarker and drug target discovery in amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal, rapidly progressive neurodegenerative disease of motor neurons for which therapeutics are limited. Improved biomarkers are imperative to improve patient care and therapeutic development. Here, we employed 35-plex isobaric tandem mass tag labeling based on isobutyl-proline reporter group (TMTpro) to perform unbiased proteomic analysis of cerebrospinal fluid (CSF) and plasma from control (n= 28, n= 31) and sporadic ALS (sALS) (n= 39, n= 41), from the Target ALS Global Natural History Study (TALS GNHS). We identified 2,875 proteins in CSF and 1,118 proteins in plasma and identified known and novel differentially expressed proteins (DEPs) between controls and sALS, some of which were orthogonally validated using immunoassay. Comparison of TMTpro-MS and Olink proximity extension assay proteomics revealed common and non-overlapping differentially expressed proteins illustrating strengths unique to each platform. This initial cross-sectional proteomic study of biofluids from the TALS GNHS, with unrestricted availability of study results to the research community, highlights the potential of this resource as a potent platform for ALS biomarker discovery.

ID: 42398690
Title: Mutant superoxide dismutase 1-catalyzed hydrogen therapy for amyotrophic lateral sclerosis achieved by intercepting oxidative stress-neuroinflammation crosstalk.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive motor neuron degeneration in the brain and spinal cord, with mutant superoxide dismutase 1 (SOD1) induced oxidative stress and neuroinflammation as key pathogenic drivers. Here, we uncover that mutant SOD1 is both a Fenton-like agent able for catalytical generation of ·OH and a hydrogenation catalyst for H2 scavenging reactive oxygen species. To enhance the bioavailability of H2, we develop an orally administered Mg2Si nanosheets based feed for sustained release of high-amount H2. On an ALS model of hSOD1G93A transgenic mice, Mg2Si feed remarkably delays ALS progression, improves the motor performance of ALS mice, and extends their lifespan. Histopathologically, oral Mg2Si treatment ameliorates motor neuron degeneration, misfolded SOD1 aggregation and reactive gliosis in spinal cord, while protecting neuromuscular junctions and ameliorating muscle atrophy during disease progression. Transcriptomic analysis demonstrates the H2-mediated down-regulation of both oxidative stress and neuroinflammatory pathways in response to the suppression of NLRP3 inflammasome activation. The proposed strategy of catalyzed hydrogen therapy offers an inspiration for metalloproteases-related neurodegenerative diseases treatment. STATEMENT OF SIGNIFICANCE: Amyotrophic lateral sclerosis (ALS) is an incurable and devastating neurodegenerative disease lacking effective clinical interventions. Although hydrogen gas (H2) exhibits promising neuroprotective potential, conventional H2 therapy is severely limited by unstable and transient H2 release, failing to sustain long-term treatment requirements for chronic ALS pathogenesis. To overcome this bottleneck, we engineer oral administrable Mg2Si nanosheets that enable sustained H2 release via gastrointestinal retention, achieving stable long-term hydrogen supplementation in vivo. Mechanistically, Mg2Si-derived H2 efficiently eliminates excess free radicals triggered by toxic mutant SOD1, and further disrupts the pathological crosstalk between oxidative stress and neuroinflammation in ALS. In transgenic ALS mice, dietary Mg2Si intervention markedly ameliorates motor dysfunction and effectively delays disease progression. Collectively, this study firstly applies Mg2Si nanomaterial-based sustained hydrogen therapy for ALS treatment, establishes a novel gastrointestinal hydrogen delivery strategy, and provides an innovative and clinically translatable paradigm for the design of hydrogen delivery systems against neurodegenerative disorders.

ID: 42404433
Title: Beyond motor neurons: peripheral TDP-43 pathology in skeletal muscle and intramuscular nerves in amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis is a progressive neurodegenerative disease characterized by accumulation of the 43-kDa TAR DNA-binding protein (TDP-43). This neuropathological signature has been well documented within the CNS; however, recent findings indicate that the phosphorylated TDP-43 additionally deposits in peripheral tissues, including skeletal muscle and intramuscular nerves. These data warrant a change of view from a neurocentric perspective of amyotrophic lateral sclerosis pathogenesis towards a broader concept of TDP-43 proteinopathy extending both within and beyond the nervous system. In this review, we focus on current evidence supporting the presence of TDP-43 pathology in amyotrophic lateral sclerosis skeletal muscle, examining its topographic distribution, molecular characteristics and associations with intramuscular nerve bundles. We also discuss the susceptibility of intrinsic muscle cells, disrupted axonal transport and impairment in protein quality control. Phosphorylated TDP-43 pathology in muscle biopsies from amyotrophic lateral sclerosis patients has emerged as a promising tool in the early diagnosis of the disease. Moreover, we discuss the relevance of these findings to amyotrophic lateral sclerosis pathogenesis and potential therapeutic implications.

ID: 42404435
Title: Value of synaptic proteins as biomarkers in amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis is a heterogeneous and rapidly progressing neurodegenerative disorder with limited treatment options. Therefore, there is a critical need for biomarkers that capture the diverse pathophysiological mechanisms underlying disease onset and progression. Emerging evidence suggests that synaptic dysfunction is an early disease mechanism in amyotrophic lateral sclerosis. Using homebrew immunoassays, we explored a panel of pre- and post-synaptic proteins in cerebrospinal fluid of patients with amyotrophic lateral sclerosis (N = 57) and controls (N = 36). The potential value as a biomarker was explored by correlating cerebrospinal fluid levels with clinical parameters and established biomarkers for amyotrophic lateral sclerosis. Higher levels of Neurogranin (NRGN) (P = 0.003) and Vesicle-associated membrane protein 2 (VAMP2) (P = 0.014) were observed in patients with amyotrophic lateral sclerosis compared with controls. VAMP2, Synaptosome-associated protein 25 kDa (SNAP25) and β-synuclein (SNCB) correlated with individual relative disease stage, but none of the biomarkers correlated with disease progression rate. High levels of SNAP25 predicted worse survival in a univariate and stepwise multivariable analysis, but significance did not persist upon including Neurofilament light chain (NfL) levels. Synaptic proteins did not correlate with cerebrospinal fluid levels of neurofilaments or biomarkers of neuroinflammation, suggesting that they reflect different pathological mechanisms in amyotrophic lateral sclerosis. Our findings warrant further investigation to determine whether increased cerebrospinal fluid levels of synaptic proteins reflect synaptic breakdown or active release of synaptic proteins. This will help elucidate how synaptic dysfunction or damage contributes to elevated levels of synaptic markers in amyotrophic lateral sclerosis, and its underlying value as biomarker.

ID: 42420559
Title: Microglial TDP-43 mediates myelin refinement and represses Tyrobp cryptic exon inclusion in mice.
Abstract: TDP-43 proteinopathy is a hallmark of neurodegenerative disorders such as amyotrophic lateral sclerosis and frontotemporal dementia where mislocalization of TDP-43 has been observed in neurons and glial cells. However, the role of TDP-43 in microglia and the consequences of its loss of function remain unexplored. Combining magnetic resonance imaging, and confocal, and electron microscopy, we uncovered structural changes and myelin abnormalities in the early postnatal brain of mice lacking microglial TDP-43. Spatial transcriptomics further revealed an enriched interferon-responsive signature associated with oligodendrocyte dysfunction. Early depletion of microglial TDP-43 led to motor deficits in adult mice. Mechanistically, knocking out TDP-43 impaired microglial ability to engulf and degrade myelin. It also led to cryptic exon inclusion in the Tyrobp mRNA, resulting in truncated DAP12 protein, thus causing defective TREM2 signaling. Our findings reveal a role for TDP-43 in regulating the TREM2-DAP12 axis in mice, highlighting a previously unrecognized mechanism through which TDP-43 controls microglial function.

ID: 42424231
Title: Neurofilament Light Chain as a Biomarker in Neurology.
Abstract: Neurofilament light chain (NfL) has emerged as a highly sensitive biomarker of neuroaxonal injury across diverse neurological disorders. This review synthesizes current evidence regarding its diagnostic, prognostic, and therapeutic-monitoring utility, while outlining major clinical limitations and emphasizing the complementary role of glial fibrillary acidic protein (GFAP). NfL concentrations increase following axonal damage and correlate with inflammatory activity, lesion burden, and long-term disability progression in multiple sclerosis. Elevated levels also reflect neurodegeneration in Alzheimer's disease, predict disease severity and survival in amyotrophic lateral sclerosis, and are associated with motor and cognitive decline in Parkinson's disease and multiple system atrophy. In acute neurological conditions, including traumatic brain injury and stroke, NfL serves as a robust indicator of the extent of neuronal injury. Interpretation is constrained, however, by substantial physiological variability related to age, renal function, body mass index, and comorbidities, limiting the utility of absolute cut-off values. GFAP provides complementary information by capturing astrocytic damage, and the GFAP/NfL ratio may aid in differentiating multiple sclerosis from neuromyelitis optica spectrum disorder. Integration of NfL with multimodal biomarkers- such as GFAP, tau proteins, proteomic and metabolomic signatures, and advanced neuroimaging-may enhance diagnostic specificity and prognostic accuracy. Future research priorities include establishing age-adjusted reference intervals, validating longitudinal thresholds, and incorporating NfL into therapeutic monitoring frameworks. Advances in these areas are expected to improve diagnostic precision and support broader clinical implementation of NfL.

ID: 42435587
Title: Precision therapeutics and innovative clinical trial design in neurodegenerative diseases.
Abstract: Neurodegenerative diseases are biologically heterogeneous disorders characterized by progressive neuronal dysfunction, overlapping molecular pathologies, and limited disease-modifying therapies. Advances in biomarker development, molecular staging, and precision medicine are reshaping therapeutic strategies and clinical trial design across Parkinson's disease, Alzheimer's disease, frontotemporal dementia, amyotrophic lateral sclerosis, Huntington's disease, and related disorders. This review summarizes emerging therapeutic approaches, including monoclonal antibodies targeting protein aggregation, immune-modulating and metabolic interventions, antisense oligonucleotides, gene replacement and genome-editing strategies, stem cell-based therapies, and neurosurgical delivery platforms and neuromodulation technologies. It also examines evolving clinical trial methodologies such as biomarker-enriched recruitment, adaptive and delayed-start designs, platform trials, decentralized models, and master protocols. Additional emphasis is placed on diagnostic biomarkers, multimodal artificial-intelligence pipelines, systems-biology perspectives, network-based therapeutic strategies, and the reproducibility and interpretability requirements for computational tools. Despite recent progress, major challenges remain, including biological heterogeneity, limited translatability of preclinical models, delivery barriers, long-term safety concerns, and inequities in access to biomarker-based care and trial participation. Future directions will require combination therapies, integrated biomarker pipelines, preventive strategies, and pragmatic trial systems capable of translating biological advances into durable and equitable clinical benefit.

ID: 42436372
Title: Plasma exosomal HERV-K transcripts are increased in amyotrophic lateral sclerosis.
Abstract: Human endogenous retrovirus-K (HERV-K) reactivation is increasingly implicated in amyotrophic lateral sclerosis (ALS), with ongoing clinical trials investigating antiretroviral therapies. However, there is limited understanding of how HERV-K is trafficked in peripheral biofluids, and the role of exosomes, nano-sized extracellular vesicles, in this process remains largely unexplored. Exosomes offer a stable and cell-specific cargo reservoir that may reflect central pathogenic processes and serve as a minimally invasive biomarker source. In this study, we isolated plasma-derived exosomes from ALS patients (n = 21) and healthy controls (n = 16), and quantified exosomal HERV-K gag, env, and pol transcript levels using SYBR Green qPCR with RNase treatment and normalization to both traditional and exosome-enriched reference genes. HERV-K pol expression was significantly elevated in ALS, with fold-changes ranging from 1.59 to 1.85 (P = 0.037-0.051). env and gag also showed increased expression, though with greater variability. Normalization to the exosome-specific gene SOD2 provided the most consistent signal. These findings suggest that exosomal HERV-K transcripts, particularly pol, could serve as accessible biomarkers for patient stratification and treatment monitoring in HERV-K-targeted ALS trials. This work establishes proof-of-concept for using exosomal cargo to track endogenous retroviral activity in neurodegeneration and supports further investigation of liquid biopsy approaches in ALS precision medicine.

ID: 42437657
Title: The Impact of Model Misspecification on the Individual Causal Association in Surrogate Endpoint Evaluation.
Abstract: Surrogate endpoints are often used in place of expensive, delayed, or rare clinical endpoints in clinical trials. However, regulatory authorities require thorough evaluation to accept these surrogate endpoints as reliable substitutes. One evaluation approach is the information-theoretic causal inference framework, which quantifies surrogacy using the individual causal association (ICA). Like most causal inference methods, this approach relies on models that are only partially identifiable. For continuous outcomes, a normal model is often used. In this study, we explored the effects of model misspecification across various scenarios. We first considered true data-generating mechanisms based on multivariate  t $$ t $$  and log-normal distributions. We then used D-vine copulas with Gaussian, Clayton, Gumbel, and Frank families to vary the unidentifiable copulas involving counterfactual pairs while preserving the observable bivariate margins, and considered intuitive restrictions on nonidentified correlations, including positivity and conditional independence. In all settings, the identifiability issue was addressed through sensitivity analysis. Finally, we illustrate the proposed sensitivity analyses using clinical-trial data from schizophrenia studies, evaluating the ICA under several modeling assumptions. The results show that, in most scenarios considered, the impact of model misspecification is small; however, certain departures from the assumed model can materially affect the surrogacy assessment.

ID: 42439427
Title: Therapeutic Potential of Mesenchymal Stem Cell-Derived Exosomes in Ocular Surface Disorders.
Abstract: The global burden of ocular surface disorders (OSDs), manifesting as progressive visual impairment and chronic discomfort, has driven urgent exploration of regenerative therapeutic strategies. Mesenchymal stem cell-derived exosomes (MSC-Exos) have emerged as promising candidates for OSD treatment, as they exhibit multifaceted therapeutic properties including immunomodulation, antifibrotic activity, and pro-regenerative capacity. This systematic review consolidates current understanding of MSC-Exo-mediated ocular surface repair mechanisms, with particular emphasis on the molecular dialog established through delivery of bioactive cargo that modulate pivotal signaling pathways. We critically analyze preclinical evidence demonstrating therapeutic efficacy across diverse OSD pathologies, including dry eye disease, corneal epithelial defects, and limbal stem cell deficiency. Notwithstanding these advances, critical barriers to clinical translation persist: (1) methodological heterogeneity arising from variable cell sourcing, culture protocols, and exosome isolation/characterization standards; (2) discordance between animal models and human OSD pathophysiology; and (3) technological limitations in scalable, clinically compatible delivery systems. Addressing these challenges requires interdisciplinary collaboration to standardize exosome production pipelines and establish robust preclinical validation frameworks, thereby accelerating the transition of MSC-Exo therapies from bench to bedside.

ID: 42442024
Title: Multimodal biophysical markers of neurodegeneration: Morphology, mechanics, and thermodynamics.
Abstract: The identification of novel noninvasive biomarkers remains a major challenge in the diagnosis of neurodegenerative diseases. Significant efforts focus on fluid biomarkers, including proteins, peptides, and miRNAs, detectable in blood plasma and peripheral blood cells. Here, we review recent findings on blood plasma and peripheral blood cells physical parameters in Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis emphasizing atomic force microscopy and calorimetry assay. Alterations in morphology, nanostructure, and stiffness of red blood cells and platelets, together with thermodynamic signatures of red blood cells and plasma, provide sensitive indicators of disease-related changes. These integrated biophysical parameters not only distinguish neurodegeneration from healthy states but also enable discrimination among different neurodegenerative disorders, highlighting their potential as minimally invasive diagnostic markers.

ID: 42443201
Title: Nuclear condensates formed by truncated mutant NEK1s impede ribosomal RNA biogenesis and drive motor dysfunction.
Abstract: NIMA-related kinase 1 (NEK1), a serine/threonine kinase, is a risk variant for amyotrophic lateral sclerosis (ALS). While the full-length NEK1 is involved in diverse cellular processes, such as DNA damage response and microtubule stability, the pathogenic mechanism of NEK1 nonsense mutations in ALS remains elusive. Here, we demonstrate that three truncated forms of NEK1 derived from ALS-related NEK1 nonsense mutations translocate from the cytoplasm to the nucleus, exhibit nucleolar localization, and simultaneously form liquid-like nucleoplasmic foci. In contrast to the diffuse cytoplasmic distribution of wild-type NEK1, these nuclear-localized truncated mutants are prone to undergo liquid-liquid phase separation both in cells and in vitro. Mechanistically, the truncated NEK1s interact with the nucleolar protein FBL, thereby impairing ribosomal RNA biogenesis and translation. Transgenic flies expressing truncated mutant NEK1s display motor dysfunction and reduced survival length, and a knock-in transgenic mouse model expressing ALS-related NEK1 mutant similarly exhibits motor deficits accompanied by ribosomal RNA dysregulation. These findings suggest that ALS-related NEK1 mutants expressing truncated forms of NEK1 cause cell toxicity by interfering with ribosomal RNA metabolism and reveal a gain-of-function mechanism in ALS pathogenesis involving NEK1.