Neuropathology and Applied Neurobiology

Twenty percent of familial amyotrophic lateral sclerosis (fALS) cases are linked to mutations in the Superoxide Dismutase 1 (SOD1) gene and accumulation of misfolded SOD1 aggregates. SOD1 misfolding from the broader ALS population without SOD1 mutations is less clear. Here, we report SOD1 seeding activity in antemortem cerebrospinal fluid (CSF) from ALS participants with and without SOD1 mutations during ALS progression. Antemortem CSF from controls, SOD1-ALS, and sporadic ALS (sALS) patients was subjected to SOD1 seed amplification real-time quaking induced conversion (RT-QuIC) assays. SOD1-ALS CSF exhibited shorter lag phase and increased ThioflavinT (ThT) fluorescence amplitude compared to healthy controls and those with spinal muscular atrophy. CSF from sALS participants, who had no mutations in SOD1 or nine other ALS risk genes, also displayed SOD1 seeding activity, indicating wild-type SOD1 is aggregate-prone in the broader ALS population. Longitudinal CSF data indicated that SOD1 seeding activity correlates with ALS progression via the ALS Functional Rating Scale Revised (ALSFRS-R) slope decline and CSF neurofilament light. Our sALS CSF cohort primarily comprised of participants less than 2 years from symptom onset, suggesting that SOD1 seeding activity is an early biomarker that may enable inclusion in clinical trials. With the FDA-approval of tofersen (Qalsody), a SOD1-lowering antisense oligonucleotide, new SOD1 diagnostic, prognostic and pharmacodynamic biomarkers may enable SOD1-targeting strategies that could benefit the broader ALS population.

BackgroundChitinases, including chitotriosidase (CHIT1) and chitinase-3-like protein 1 (CHI3L1), are markers of neuroinflammation, a key process in amyotrophic lateral sclerosis (ALS). Tear fluid (TF) can be collected non-invasively and may represent a promising alternative to CSF or blood to study chitinases. MethodsTF was collected from 50 ALS patients and 50 control subjects using Schirmer strips. CHIT1 and CHI3L1 levels in TF, serum, and CSF were quantified using ELISA. Serum NfL was measured using SIMOA. The frequency of a 24 bp-duplication polymorphism in the CHIT1 gene influencing CHIT1 expression was assessed by PCR. ResultsNo group differences in the distribution of the CHIT1 polymorphism were detected. Carriers of the polymorphism in both ALS and controls showed lower CHIT1 levels in serum and TF. CHI3L1 levels in TF were higher in ALS patients compared to controls (p = 0.007), consistent with changes in CSF but not serum. In ALS, males showed higher TF CHIT1-values compared to females (p = 0.009). Combining TF chitinase values with serum NfL values improved discrimination between ALS and controls. ConclusionsChitinases are detectable in TF, and CHI3L1 levels recapitulate changes observed in CSF, highlighting its potential for non-invasive longitudinal assessment. Furthermore, chitinase values in TF, together with serum NfL, may act complementary by capturing distinct aspects of the disease, neuroinflammation and axonal damage. These results suggest TF chitinases and serum NfL could complementarily contribute to the diagnosis and monitoring of the disease, and call for further evaluation of TF as a biomarker source in ALS.

Multiple system atrophy (MSA) is a sporadic progressive neurodegenerative disorder characterised by central nervous system alpha-synuclein inclusions. MSA pathologically most commonly shows a spectrum of two patterns, olivopontocerebellar atrophy and striatonigral degeneration, with significant overlap. Although germline variants are unlikely to play a major role, an association with the KCTD7 gene was recently reported. Somatic mutations are abundant in the brain, and may play a role in neurodegeneration. In MSA, somatic SNCA (alpha-synuclein) copy number gains occur, but single nucleotide mutations have not been investigated. In Alzheimers disease, somatic mutations in tumour suppressor genes were reported in microglia. We hypothesised that brain somatic mutations in SNCA, KCTD7, or the tumour suppressor genes mutated in Alzheimers, may contribute to MSA. To test this, we developed a targeted duplex sequencing pipeline using unique molecular identifiers, encompassing SNCA, KCTD7, and 10 tumour suppressor genes. Seven of these are involved in clonal haematopoiesis, an age-related process which predisposes to haematological malignancy, and can be subdivided into myeloid and lymphoid, based on the cell type affected, with the former much more frequent. We analysed DNA from the cerebellum, cingulate cortex, and putamen of 20 MSA cases (10 olivopontocerebellar atrophy, 10 striatonigral degeneration) and 9 controls. We observed an enrichment of clonal haematopoiesis gene mutations in MSA brains (median 1 vs 0, p=0.054). These included mutations in DNMT3A and TET2, the most frequently affected myeloid clonal haematopoiesis genes, and a recurrent mutation in three cases in KMT2D, a lymphoid clonal haematopoiesis gene. Clonal haematopoiesis mutations were often found in multiple brain regions, and multiregional mutations occurred in 12/20 MSA cases versus 1/9 controls (p=0.020), with 11 cases harbouring clonal haematopoiesis mutations in all three brain regions, compared to 0/9 controls (p=0.005). In striatonigral degeneration, clonal haematopoiesis mutations showed elevated variant allele fractions in the most pathologically affected region, the putamen, versus the cerebellum (p=0.013). MSA clonal haematopoiesis mutations included eight unique non-synonymous variants, which had higher allelic fractions than synonymous changes (p=0.076), and five of these were predicted to confer a proliferative advantage and were found in multiple brain regions. We detected no coding SNCA mutations, and the small number of KCTD7 variants, including one coding deletion, precludes any conclusions. These findings reveal enrichment of clonal haematopoiesis mutations in MSA brain, potentially due to infiltration from the periphery, suggesting a disease-associated proliferative process extending beyond peripheral haematopoiesis.

Meningiomas are the most common primary brain tumors and, despite their benign reputation, often behave aggressively. Meningiomas are morphologically heterogeneous, yet the full significance of their histologic diversity is unclear. This is in large part because many features are not readily quantifiable by traditional observer-based light microscopy. Molecular testing improves prognostic stratification, but is not universally accessible. We therefore sought to determine whether an artificial intelligence (AI)-trained program could predict specific genomic and epigenomic patterns in meningiomas, and whether it could extract more prognostic information out of standard hematoxylin and eosin (H&E) histopathology than the current WHO classification. To do this, we developed Morphologic Set Enrichment (MSE), an interpretable computational pathology framework that quantifies statistical enrichment of morphologic patterns, cells, and tissue architecture from H&E whole-slide images. The MSE meningioma histology program was able to accurately predict DNA methylation subtypes and concurrent chromosome 1p/22q losses, in the process identifying specific morphologic patterns associated with key genomic and epigenomic alterations. It also added prognostic value independent of standard clinical and pathological variables. These results demonstrate that AI-based quantitative morphologic profiling can capture clinically and biologically relevant information that redefines risk stratification for meningiomas, incorporating histological information not included in existing grading schemes.

Despite important advances in understanding the etiopathology of multiple sclerosis, factors determining disease progression remain partially understood and often difficult to predict. Specific diagnostic and prognostic biomarkers are needed to optimize the risk-benefit ratio of treatment for each patient. The aim of our study was to identify a cerebrospinal fluid proteomic signature associated with diagnosis and short- to mid-term prognosis across the multiple sclerosis continuum. Our multicentric cohort study analyzed CSF samples from 120 patients using a proteomics data-independent acquisition strategy. Differentially expressed proteins were identified across diagnostic groups: 62 patients with multiple sclerosis, 15 patients with clinically isolated syndrome, and 43 healthy controls. We also compared the CSF of patients with no evidence of disease activity with those with disease activity at 2 and 5 years of follow-up. A diagnostic and prognostic classification model was built using iterative cross-validated logistic regression models on shared differentially expressed proteins across these two comparisons. A total of 1,257 proteins were quantified, and 162 differentially expressed proteins were identified across comparisons. We identified a set of ten proteins associated with the diagnosis and prognosis of multiple sclerosis, including previously identified potential biomarkers (CH3L2, IGHG1, IGKC, LAMP2, ADA2), proteins known to be involved in the pathophysiology of multiple sclerosis (A0A8J8YUT9, AT2A2, CO3A1) and two yet unreported proteins (DSC2 and MMRN2). Multivariate models based on these proteins achieved good accuracy for the diagnosis of MS compared with CIS (area under the receiver operating characteristics curve [AUROC] up to 80% using 3 proteins) and prognosis (NEDA vs. EDA; AUROC up to 96% at 2 and 5 years; using 5 proteins). These results, which will require further investigation to validate the new biomarkers, open new perspectives on multiple sclerosis pathophysiology and therapeutic targets.

BackgroundALS is increasingly recognized as a biologically heterogeneous disease in which several molecular and pathological mechanisms converge on a similar clinical phenotype. One of these molecular markers is ferritin accumulation which is observed in a subset of ALS cases and has been shown to directly correlate with TDP-43 pathology in some brain regions. Additionally, TDP-43 proteinopathy is observed outside of ALS which may complicate the interpretation of case vs control approaches to target discovery. Here, we propose a pathology-stratified approach to empower targeted theranostics. We hypothesised that biologically distinct ALS subtypes may be defined by specific metabolic dysfunction linked to brain-accumulated ferritin and TDP-43 pathology. MethodsPost-mortem primary motor cortex tissue from 15 ALS cases and 20 age- and sex-matched controls was stratified, using immunohistochemistry, by single- or co-occurrence of ferritin accumulation, and pathological TDP-43. Untargeted metabolomics (>1,000 metabolites) was performed, and samples were stratified into dual positive (ferritin and TDP-43), single positive (either), or negative. Group-discriminating metabolites were identified using partial least squares discriminant analysis. ResultsDual ferritin and TDP-43 pathology reflected a distinct metabolomic profile, separable from single-pathology states. This dual positive metabolic signature was characterised by disruption of lysophospholipid, lysoplasmalogen, and fatty acid metabolism, consistent with impaired membrane and energy homeostasis. In contrast, pathological TDP-43 presence without ferritin, was characterised metabolically by significant depletion of secondary bile acids and increase in glycosylation markers, whilst ferritin accumulation alone reflected significant increase in oxidative stress and depletion of lipid peroxidation inhibition markers. The dual positive state suggests failure of compensatory metabolic responses present in single-pathology conditions. ConclusionsFerritin accumulation and TDP-43 pathology define biologically distinct subtypes associated with ALS with divergent metabolic vulnerabilities. The metabolic signature associated with dual pathology provides a mechanistic correlate to MRI-visible ferritin accumulated iron, supporting paired non-invasive biomarker and target discovery for pathology-dependent patient stratification. These findings argue for pathway-targeted, subtype-specific therapeutic strategies and highlight the necessity of precision medicine approaches in ALS. Short abstractAmyotrophic lateral sclerosis (ALS) exhibits profound molecular heterogeneity that is not captured by current clinical classifications. Additionally, TDP-43 proteinopathy is observed outside of ALS which may complicate the interpretation of case vs control approaches to target discovery. Here, we propose a pathology-stratified approach to therapeutic target discovery, identifying convergent iron dysregulation and TDP-43 pathology with specific metabolic consequences. Post-mortem primary motor cortex tissue from 15 ALS cases and 20 controls was investigated for ferritin, and pathological TDP-43 using RNA aptamer-based immunostaining. Untargeted metabolomics (>1,000 metabolites) was performed with stratification into dual positive, single positive, or negative groups, followed by partial least squares discriminant analysis. Dual ferritin and TDP-43 pathology produced a distinct metabolic state characterised by disruption of lysophospholipid, lysoplasmalogen, and fatty acid metabolism, indicating impaired membrane integrity and energy homeostasis. In contrast, single positive states engaged divergent compensatory pathways involving bile acid metabolism, glycosylation, or oxidative stress regulation. Ferritin-TDP-43 convergence defines a metabolically decompensated ALS subtype corresponding to MRI signatures, providing a mechanistic basis for imaging-guided, pathology-dependent patient stratification and targeted intervention. Key FindingsO_LIMetabolically distinct subtypes were defined by the presence or absence of ferritin-associated iron accumulation and TDP-43 pathology in the primary motor cortex. C_LIO_LIConcurrent ferritin and TDP-43 pathology produce a unique, metabolically decompensated state characterised by disrupted lipid, membrane, and energy metabolism, distinct from either pathology alone. C_LIO_LISingle positive states engage divergent compensatory metabolic pathways, which are lost when ferritin and TDP-43 co-occur. C_LIO_LIThe metabolic signature of dual positivity provides a mechanistic correlate to the MRI-visible motor band sign. C_LIO_LIThese findings support the use of pathology-based stratification of ALS patients and a foundation for pathway-targeted, precision therapeutic approaches. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/711539v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@69d482org.highwire.dtl.DTLVardef@1fee3a4org.highwire.dtl.DTLVardef@1135017org.highwire.dtl.DTLVardef@ef3f96_HPS_FORMAT_FIGEXP M_FIG C_FIG

BackgroundAmyotrophic lateral sclerosis (ALS) is clinically heterogeneous, and genetic modifiers may drive molecular endophenotypes without obvious clinical stratification. The apolipoprotein E {varepsilon}4 (APOE {varepsilon}4) allele is a major Alzheimers disease risk allele, but its biological impact in ALS remains unclear. MethodsUsing the Answer ALS cohort, longitudinal motor, cognitive, and neuropsychiatric measures were modelled using mixed-effects approaches. Patient induced pluripotent stem cell-derived motor neuron multiomics (chromatin accessibility, transcriptomics, and proteomics) were analysed using supervised machine learning. Plasma SomaScan profiling was used to derive an APOE {varepsilon}4-associated protein signature and to test its stability across serial visits, biological pathway enrichment, and associations with clinical progression. ResultsAPOE {varepsilon}4 carriage was not associated with baseline severity or rate of functional decline and showed no consistent effects on cognitive or neuropsychiatric trajectories. Motor neuron multiomic profiles similarly demonstrated no reproducible APOE {varepsilon}4 signal and did not reliably classify genotype. In contrast, plasma proteomics identified an APOE {varepsilon}4 protein signature that classified {varepsilon}4 status with high accuracy in ALS (AUC 0.98) and non-ALS motor neuron disease (AUC 0.86) and was enriched for immune and inflammatory biology. This systemic signature was highly stable across repeated sampling, indicating a persistent genotype-associated state. Within this plasma endophenotype, a small set of proteins tracked functional decline and a composite score stratified fast versus slow progression. Baseline composite scores were elevated in APOE {varepsilon}4 carriers in both ALS and neurologically unimpaired controls, consistent with a stable systemic shift detectable beyond overt disease status. ConclusionsAPOE {varepsilon}4 defines a persistent, immune-enriched systemic proteomic endophenotype in ALS that is not captured by clinical trajectories or motor neuron-only profiling yet relates to disease progression. Plasma-based, genotype-informed endophenotyping offers a translational pathway for biomarker stratification and therapeutic prioritisation in ALS and potentially other heterogeneous neurodegenerative disorders.

ObjectiveBrain branks preserve extensive material relevant to neurodegenerative disease research. As these collections age, tissue becomes archival, raising the question of whether long-term fixed and stored human brain tissue remains suitable for contemporary immunohistochemical analyses. Materials and MethodsForty-one autopsy brains collected between 1946 to 1980 were examined. For each case, midbrain and hippocampus were available both as original paraffin-embedded blocks and as tissue stored long term in fixative. New paraffin blocks were prepared from the long-term fixated tissue. Sections from original and newly prepared blocks were immunohistochemically stained for -synuclein, hyperphosphorylated tau and amyloid-{beta}. Immunoreactivity was assessed using semi-quantitative scoring. ResultsOriginal blocks consistently showed good staining intensity and morphological preservation for each protein pathology. Newly prepared blocks showed slightly lower semi-quantitative scores for Lewy-related pathology, without statistically significant differences, except for astrocytic -synuclein in the substantia nigra in cases from the 1960s. Tau pathology displayed modestly reduced labelling, particularly of the neuropil threads and neurofibrillary tangles, most evident in cases from the 1950s. Amyloid-{beta}-positive senile plaques showed similar or slightly higher scores in newly prepared blocks, with no significant differences across regions. ConclusionHuman brain tissue preserved as paraffin-embedded blocks or stored in fixative for up to 78 years remains suitable for immunohistochemical analyses. Adequate-to-good detection of aggregated of -synuclein, hyperphosphorylated tau and amyloid-{beta} is achievable, indicating preserved pathological hallmarks of Lewy Body Disease and Alzheimers Disease in archival tissue.

BackgroundGlioblastoma (GBM), Isocitrate dehydrogenase-wildtype (IDH-wt) is characterised by diffuse infiltration, with progression often arising from perilesional tissue and occult white-matter damage. We investigated whether radiomics from the T2/FLAIR-defined oedema and the structural disconnectome improve prediction of progression-free survival (PFS). MethodsWe retrospectively analysed 387 adults with newly diagnosed GBM, IDH-wt treated at a single tertiary centre (2005-2020). A deep-learning pipeline segmented enhancing tumour, non-enhancing tumour, and oedema on pre-operative MRI; lesion masks were propagated to normative tractography to derive disconnectome maps. 3-D shape radiomic features extracted for each segmented region underwent appropriate feature selection. Finally, 10 tumour and 9 oedema radiomics were combined with 6 clinical features to train 3 survival models (Random Survival Forest (RSF), XGBoost, Cox proportional hazards (CPH)) that were evaluated on a held-out 20% test set using Harrells C-index, Kaplan-Meier risk stratification and time-dependent ROC curves. ResultsThe best performance was achieved by RSF using all clinical and radiomic features (C-index 0.665 vs 0.595 for clinical features only, p=0.088). Models including oedema radiomics outperformed those using tumour radiomics alone, and disconnectome features, derived from both tumour and oedema regions, were repeatedly selected among the top predictors across algorithms. Combining radiomic and clinical features improved risk stratification and 12-month early-versus-late recurrence classification (AUC 0.704 vs 0.582 for clinical features alone). ConclusionsIntegrating perilesional oedema and white-matter disconnectome MR features with clinical and molecular data enhances prediction of PFS in GBM, IDH-wt. These network-aware, multimodal survival models may support personalised risk-adapted treatment strategies pending external validation. Key Points- GBM IDH-wt exhibits a high recurrence rate despite aggressive treatment. - Addition of high-dimensional oedema and disconnectome radiomic features to clinical features showed consistent improvement in the test performance of 3 ML models. - This can support informed clinical decision-making. Importance of the StudyPrediction of progression free survival (PFS) for a patient with highly recurrent glioblastoma IDH-wt traditionally relies on clinical history, demographics, and molecular markers of the tumour. Recent literature reveals the tumours disruptive nature through its invasion of white-matter tracts and identifies its microenvironment, particularly the perilesional oedema, as a harbour of treatment resistant tumour cells. This study is the first to combine high-dimensional radiomic features of the tumour, the oedema, and their disconnectome with clinical and treatment factors to predict PFS. Using 3 model architectures (XGBoost, RSF, and CoxPH), we demonstrate consistent directional improvements in performance, on addition of radiomic features to clinical baseline models. Furthermore, oedema and disconnectome radiomics are identified as top predictor features across algorithms. This proof-of-concept study provides a reproducible multimodal pipeline, reaffirms the usability of MR radiomics, and identifies features of the oedema and the structural connectome as promising biomarkers, demanding large-scale external validation.

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disorder characterized by the cytoplasmic aggregation and nuclear depletion of the TDP-43 protein. The latter impairs TDP-43 function as an RNA-binding protein and compromises the repression of cryptic splicing events, affecting both glutamatergic upper motor neurons and cholinergic lower motor neurons. This study systematically investigated the molecular and functional consequences of TDP-43 knockdown in human induced pluripotent stem cell (hiPSC)-derived glutamatergic neurons (iGNs) and cholinergic motor neurons (iMNs) using antisense oligonucleotides. The results demonstrated that TDP-43 loss elicits widespread, cell-type-specific changes in gene expression and alternative splicing. Notably, a shared subset of ALS-associated targets, including STMN2 and UNC13A, were consistently downregulated and mis-spliced across both neuronal subtypes. Functionally, Microelectrode Array (MEA) electrophysiology recordings revealed that TDP-43 knockdown induces a hyperexcitable phenotype in both neuronal populations, though they exhibited distinct network patterns: iGNs displayed synchronized bursting and significant shifts in overall electrophysiological profiles, while iMNs showed asynchronous firing. Furthermore, the inclusion of astrocytes in co-culture models expanded the repertoire of detectable cryptic splicing, including an event in HDGFL2 previously identified in patient cerebrospinal fluid. Despite these profound molecular and functional deficits, TDP-43 depletion did not impact neuronal viability or increase susceptibility to glutamate-induced excitotoxicity. These findings validate hiPSC-derived iGNs and iMNs as relevant models for ALS and highlight the critical necessity of considering cell-type specificity when elucidating pathogenesis and developing targeted therapies.

BACKGROUND: Increasing evidence suggests that accurate prediction of Alzheimer disease (AD) symptom onset requires more than amyloid- and tau-centric biomarkers such as cerebrospinal fluid (CSF) A{beta}42/40, total tau and p-tau181 and plasma p-tau217. Autosomal dominant AD (ADAD), caused by pathogenic PSEN1, PSEN2 and APP mutations with predictable age at symptom onset, presents a unique opportunity to characterize the chronological changes in proteins beyond amyloid and tau and clarify them as early biomarkers of disease onset or as biomarkers related to disease staging and progression monitoring. METHODS: We measured 972 CSF samples corresponding to 484 participants of the Dominantly Inherited Alzheimer Disease Network (DIAN) using the NULISASeq 120 CNS Disease Panel. We first benchmarked the technology against gold-standard measurements followed by the identification of proteins that were differentially abundant in relation to mutation status and symptomatology. Next, we determined the chronological emergence of protein changes in relation to the estimated years to onset (EYO). Finally, we assessed whether specific protein measures improved the prediction of EYO in the ADAD. FINDINGS: NULISA measurements were comparable to those previously published. We demonstrated that known early alterations in CSF amyloid and tau were followed by inflammatory and neurodegenerative responses suggesting that clinical manifestation of AD happens before the inflammatory processes is fully developed. Finally, we found a multi-protein composite approach for predicting EYO that outperformed single biomarker values. INTERPRETATION: Our results suggest that the main CSF proteomic landscape changes in ADAD are due to the presence of a pathogenic mutation and occur prior to symptom onset. Improved performance of multi-protein composite to predict EYO compared to single biomarker values highlights the added value of multiplex proteomic signatures for biomarker panel development. FUNDING: National Institute on Aging, Alzheimers Association, German Center for Neurodegenerative Diseases, Raul Carrea Institute for Neurological Research, Japan Agency for Medical Research and Development, Ministry of Health & Welfare and Ministry of Science and ICT, Republic of Korea, Spanish Institute of Health Carlos III.

While 18F-Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) is an established biomarker in amyotrophic lateral sclerosis (ALS), the metabolic correlates of motor neuron disease motor variants remain poorly defined. This is why we investigated patterns of cerebral glucose metabolism across the spectrum of motor neuron disorders (MND), including progressive muscular atrophy (PMA), primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS). We retrospectively included 18 PMA, 25 PLS and 43 matched non-hereditary ALS patients according to most recent diagnostic criteria. FDG-PET imaging revealed similar widespread hypometabolism in PMA, as in ALS, whereas PLS showed a more focal motor cortical pattern of hypometabolism. Despite clinical differences between MND subtypes, PMA and ALS showed similar FDG-PET metabolic patterns, whereas PLS exhibited a more restricted cortical signature in this retrospective study.

Introduction: Glioblastoma multiforme (GBM) remains the most lethal primary brain tumor with median survival of 14-15 months. Current prognostic markers inadequately stratify patient outcomes. PINK1 (PTEN-induced putative kinase 1), a mitochondrial kinase regulating mitophagy and cellular stress responses, has emerged as a promising prognostic candidate. Our preliminary analysis of 20 GBM cases demonstrated significant PINK1 expression with correlation to aggressive phenotypes (Turizo Smith et al., 2025). This multicenter study aims to prospectively validate PINK1 as a prognostic biomarker for survival and functional outcomes in a Latin American cohort. Methods and analysis: PINK1-GBM Colombia is a multicenter, observational cohort study across four tertiary hospitals in Bogota, Colombia (Hospital de Kennedy, Hospital El Tunal, Hospital Santa Clara and Hospital Universitario de la Samaritana). We will enroll at least 26-50 adults (18+ years) with newly diagnosed IDH-wild type GBM undergoing surgical resection. PINK1 expression will be quantified by immunohistochemistry (IHC) on formalin-fixed paraffin embedded (FFPE) tissue using standardized protocols. Primary outcomes: overall survival (OS) and progression-free survival (PFS). Secondary outcomes: functional status trajectories (KPS/ECOG). Follow-up extends 24 months with clinical, imaging (RANO 2.0), and telephone assessments. Survival analyses will employ Kaplan-Meier methods, log-rank tests, and Cox proportional hazards models adjusted for established prognostic factors. Ethics and dissemination: Approved by Universidad Nacional de Colombia Ethics Committee (Acta 001, February 5, 2026; Ref: 2.FM.1.002-CE-002-26), Subred Sur Occidente (P-AP-19-2025, July 11, 2025), and Subred Centro Oriente (CEI 067/2025, October 24, 2025). Conducted per Declaration of Helsinki and Colombian Resolution 8430/1993. Results will be disseminated via peer-reviewed publication, international conferences, and thesis submission.

Huntingtons disease is an inherited neurodegenerative disorder caused by a CAG repeat expansion in exon 1 of the Huntingtin (HTT) gene, encoding an expanded polyglutamine tract in the huntingtin (HTT) protein. The pathogenic CAG repeat of HTT is unstable and undergoes progressive somatic expansion in specific brain cells and peripheral tissues throughout life. Genes involved in DNA mismatch repair pathways, which promote repeat expansion, have been identified as genetic modifiers of the disease. Consequently, the rate of CAG repeat expansion is a key determinant driving the age of onset and disease progression. As the CAG repeat expands, alternative processing of HTT pre-mRNA increasingly favours production of the HTT1a transcript, which encodes the highly pathogenic and aggregation-prone HTT1a protein. This process provides a mechanistic link between CAG repeat expansion and disease pathogenesis, as increased HTT1a production accelerates HTT aggregation and neuronal dysfunction. HTT1a has previously been detected in Huntingtons disease mouse models by using immunoprecipitation coupled with western blotting, homogeneous time-resolved fluorescence (HTRF) and Meso Scale Discovery (MSD) bioassays, and immunohistochemistry. These approaches were developed using MW8, a neoepitope antibody that specifically recognizes the C-terminus of HTT1a. MW8 is a relatively weak antibody with limited detection sensitivity. To generate more robust HTT1a-specific reagents, two novel recombinant antibodies, 1B12 and 11G2, have been developed for evaluation. Using an allelic series of knock-in (HdhQ20, HdhQ50, HdhQ80, HdhQ111, CAG140 and zQ175) mice, alongside transgenic YAC128 and N171-82Q models, we extensively evaluated and compared the performance of MW8, 1B12 and 11G2. We demonstrate that 1B12 and 11G2 function as HTT1a-specific neoepitope antibodies by immunoprecipitation with western blotting, and by immunohistochemistry. To enhance HTT1a detection using HTRF and MSD technology platforms, we further evaluated the performance of 1B12 and 11G2 in HTT bioassays using cortical lysates from zQ175 and YAC128 mice. In zQ175 mice, enhanced detection of aggregated HTT1a by HTRF and MSD revealed that HTT fragments longer than HTT1a can be incorporated into HTT1a-containing aggregates. The most sensitive assays were subsequently applied across the allelic series of knock-in mice to assess the effect of polyglutamine length on bioassay performance. For optimal sensitivity, we recommend the preferential use of 1B12 for HTRF assays and 11G2 for MSD assays. Collectively, these findings establish 1B12 and 11G2 as robust antibodies to reliably detect and track HTT1a pathology in vivo and promotes the replacement of previously used MW8-based experimental approaches. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=191 HEIGHT=200 SRC="FIGDIR/small/708805v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@16d10faorg.highwire.dtl.DTLVardef@1759f41org.highwire.dtl.DTLVardef@12a8c21org.highwire.dtl.DTLVardef@55fe6a_HPS_FORMAT_FIGEXP M_FIG C_FIG Osborne et al. used Huntingtons disease mouse models to evaluate and compare the performance of HTT1a-specific neoepitope antibodies by using immunoprecipitation with western blotting, bioassays, and immunohistochemistry. In contrast to MW8, they establish that 1B12 and 11G2 are robust antibodies to reliably detect and track HTT1a pathology in vivo.

SARM1 and NMNAT2 are two well described players in the Programmed Axon Death (PAxD) pathway. However, less is known about their transcriptional regulation, especially in humans, despite evidence that their expression levels influence axon vulnerability and thus modulation of expression presents a potential therapeutic target. Here, we used in-cell luciferase assays to functionally study the promoter regions of the human NMNAT2 and SARM1 genes. We find that human NMNAT2 expression can be driven by cAMP, acting through one cAMP response element (CRE), compared to two in mice. Naturally occurring single-nucleotide variants exist within the CRE, some of which lower NMNAT2 promoter activity by more than 50%. We also report an ultra-rare single nucleotide variant in the NMNAT2 promoter in an ALS patient in Project MinE. This variant demonstrates pathogenic potential by lowering NMNAT2 promoter activity in our assay. Project MinE also reveals a common SARM1 promoter variant that significantly increases SARM1 promoter activity in our assay. Thus, several single nucleotide changes in the NMNAT2 and SARM1 promoters modify transcription levels in the direction that would predict an increase in susceptibility to PAxD. These promoter variants refine our understanding of regulatory mechanisms affecting NMNAT2 and SARM1 expression and, together with previously reported coding variants for these genes, expand the catalogue of functionally relevant variants for future association studies in neurodegenerative diseases, including peripheral neuropathies and motor nerve disorders.

Amyotrophic Lateral Sclerosis (Lou Gehrigs disease) is a progressive neurodegenerative disease affecting hundreds of thousands of people worldwide. It is characterized by the degeneration of the neurons in the brain and spinal cord of the patients, leading to a loss of control of muscles. Over time, without nerves to stimulate them muscles tend to atrophy. ALS may occur sporadically or run in families; many mutations have been identified for the latter. Treatment of ALS is mostly limited to three approved therapeutic agents: riluzole, edaravone, and tauroursidiol/ sodium phenylbutyrate. Among these, riluzole remains the most effective despite its early discovery. There are no conclusive meta-analysis comparing riluzole monotherapy to all possible co-therapies present. In this work we have attempted to address such a concern and observed that no adjunct therapy significantly improved the performance of riluzole. However, mitochondrial/ oxidative stress modulator and neuroimmune/ neuroexcitability modulator co-therapy exhibited positive trends. Surprisingly, trials were mainly confined to the USA and European countries, indicating unequal demographic representation in ASL research. We have concluded that large double blinded inter-continental RCTs to be carried out for better understanding of the scenario.

Alzheimers Disease (AD) is distinguished by the presence of two key pathological features: amyloid plaques, accumulations of proteolytic products of Amyloid Precursor Protein, and neurofibrillary tangles (NFTs), intracellular aggregations of microtubule-associated protein tau. NFTs first appear in particular entorhinal cortex (EC) neurons (called pre-alpha neurons) in asymptomatic patients, then continue to spread through other connected brain regions as the disease progresses. This stereotypical progression of tauopathy through synaptically connected brain regions (i.e. Braak stages) not only suggests that the tauopathy in AD spreads transsynaptically, it also raises the question whether particular neuronal subtypes and/or brain regions are especially prone to tauopathy. We explored this question by overexpressing wildtype human tau protein (hTau) in a variety of entorhinal and neocortical neuronal subtypes. We then compared the tendencies of different neuronal cell types to develop different pathological tau species over time and found that tau pathology does indeed develop at markedly different rates in different neuronal subtypes. Perhaps unsurprisingly, the EC is particularly prone, with the likely rat cognates of the pre-alpha neurons (ECLII fan cells) among the first to express pathological tau label. Fan cells were not, however, the neurons with the greatest vulnerability to generate pathological tau species: subsets of ECLIII neurons were found to express disproportional amounts of pathological tau. This is of particular interest given that the next structures to develop AD-related tauopathy after the EC in patients are CA1 hippocampus and subiculum, where ECLIII neurons project, rather than the dentate gyrus and CA3, where ECLII fan cells project. These results demonstrate differential susceptibility of different neuronal subtypes to pathological tau species and suggest distinct roles for different entorhinal neuronal subtypes in the propagation of the tauopathy underlying AD-related neurodegeneration.

BackgroundNeuroinflammation is a common hallmark of primary tauopathies, and is associated with worse clinical outcomes over time. However, accurate prognosis in these disorders remains challenging, and current fluid biomarkers provide limited insight into the contribution of peripheral immune cells to PSP/CBS pathogenesis. Our study aims to characterise blood-based immune cell profiles in patients with progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS), and test their associations with neurodegeneration and clinical outcomes. MethodsPeripheral blood immune cells from fresh whole blood were characterized with high-dimensional mass cytometry (29 markers) in n=60 people with PSP/CBS and n=21 age- and sex-matched controls. Cell type abundance was defined as the ratio of counts for each gated population divided by total live cells. Hierarchical clustering of cell types and principal component analysis were used to derive data-driven immune clusters. Correlation network analysis and diffusion-based network propagation integrated cell counts with plasma inflammation markers to prioritise mediators of intercellular signalling. Associations between immunological markers, plasma concentrations of neurofilament light chain (NfL), cognition, and survival were assessed using regression and Cox proportional hazards models. ResultsPatients with PSP/CBS showed a global increase in covariance among immune cell populations, indicating heightened coordination within the peripheral immune network. A monocyte-driven cluster (Cluster 1) showed higher scores in PSP/CBS, reflecting impaired phenotypic transition from classical to nonclassical monocytes, and was associated with higher NfL levels, poorer cognitive performance, and worse prognosis. In contrast, a Treg-driven cluster (Cluster 2) showed lower scores in PSP/CBS, and was associated with better cognition and longer survival. Integrated multimodal networks identified a small set of immune-regulatory molecules and cytokines mediating crosstalk between Treg/Th17-like cells and monocytic populations, supporting a dysregulated Treg-monocyte axis in PSP/CBS. ConclusionsWe identified peripheral blood-based immunophenotypic profiles of individuals with PSP/CBS that are associated with neurodegeneration, cognitive decline, and survival. Dysregulated monocyte maturation and reduced Treg-related immune configurations are enriched in patients with worse outcomes, suggesting that specific peripheral immune cell subsets may serve as fluid biomarkers and potential immunotherapy targets in primary tauopathies.

The assembly of TAR DNA-binding protein 43 (TDP-43) into amyloid filaments within neurons is a hallmark of multiple neurodegenerative diseases, including motor neuron diseases (MND), frontotemporal dementias (FTD) and limbic-predominant age-related TDP-43 encephalopathy (LATE). These diseases result from the deterioration and loss of neurons, with synaptic dysfunction and neuronal hyperexcitability being prominent early events. Pathogenic mutations in the TDP-43 gene, TARDBP, that promote filament formation have established a causal role for TDP-43 assembly in neurodegenerative diseases. However, the molecular mechanisms underlying filament accumulation and their contribution to neurodegeneration are poorly understood. TDP-43 filaments can propagate between neurons in a prion-like manner, which may underlie the progressive spread and accumulation of TDP-43 pathology in disease. Here, we studied early stages of TDP-43 filament accumulation following internalisation of patient-derived TDP-43 filaments by mouse and human cortical neurons. Using proximity labelling, we identified molecular environments and putative interactions of TDP-43 filaments. We found that TDP-43 filaments accumulated at synapses, particularly in proximity to the presynaptic active zone, which we confirmed in FTD patient brain sections. Electron cryo-tomography (cryo-ET) directly visualised abundant TDP-43 filaments spanning the presynaptic cytoplasm in situ, which contacted synaptic vesicles and the plasma membrane. Functional measurements revealed that the accumulation of TDP-43 filaments led to presynaptic dysfunction and subsequent neuronal hyperexcitability. These findings suggest that synapses are a major early site of TDP-43 filament accumulation, relevant to their propagation, and directly link TDP-43 filament gain of function to synaptic dysfunction.

Neurodegenerative diseases often feature a prolonged presymptomatic phase during which pathological processes evolve before overt clinical manifestation. In Amyotrophic lateral sclerosis (ALS), defining this prodromal period is critical for identifying early disease features and the optimal window for intervention, yet it remains poorly characterised. In this cross-sectional study, we compared 475 ALS patients with 285 controls recruiting across 20 ALS expert centres in Germany and Switzerland. Participants completed a structured digital questionnaire capturing prodromal complaints, healthcare utilisation, comorbidities, lifestyle factors, and weight changes during the 10 years preceding ALS symptom onset. ALS patients reported substantially higher burden of prodromal complaints than controls (OR=7.50, 95% CI 4.27-13.17; P < 0.001; Padj < 0.001), particularly neuro-motor, sensory, and pain-related symptoms. Prior to symptom onset, ALS patients more frequently consulted neurologists (OR=1.26, CI 1.10-1.44; P < 0.001; Padj = 0.007). Speech therapy consultations were significantly more common among female patients (OR = 2.35, CI 1.05-5.28; P = 0.038) and those with bulbar-onset ALS (OR = 8.67, CI 3.80-19.77; P < 0.001). Prodromal musculoskeletal dysfunction was more frequently reported by ALS patients and exhibited sex- and site-specific patterns. Herniated discs were reported more often by male ALS patients (OR=2.21, CI 1.04-4.68; P = 0.038) and by those with spinal-onset disease (OR=2.32, CI 1.38-3.93; P = 0.002). ALS patients more often completed lower secondary education (OR=1.93, CI 1.24-3.01; P = 0.004; Padj = 0.020) and were more likely to have worked in physically demanding occupations (OR=2.21, CI 1.42-3.43; P < 0.001; Padj = 0.003). Lifestyle factors differed significantly, with higher prior consumption of caffeine (OR=7.21, CI 3.27-15.89; P < 0.001; Padj < 0.001), alcohol (OR=2.25, CI 1.47-3.43; P < 0.001; Padj = 0.002), and cigarettes (OR=1.64, CI 1.20-2.24; P = 0.002) among ALS patients (Padj = 0.011). Weight trajectories differed by sex (P = 0.009), with male ALS patients showing significant loss already during the pre-onset phase (P < 0.001). These findings demonstrate that ALS is preceded by a distinct prodromal phase characterised by mild motor impairment, altered healthcare engagement, and sex- and site-specific patterns in comorbidities, lifestyle, and metabolic change. Characterising these early features of ALS may facilitate earlier diagnosis and enable timely enrolment in clinical trials.