ID: 29599716
Title: Atrophy in the Thalamus But Not Cerebellum Is Specific for C9orf72 FTD and ALS Patients - An Atlas-Based Volumetric MRI Study.
Abstract: Background: The neuropathology of patients with frontotemporal dementia (FTD) or amyotrophic lateral sclerosis (ALS) due to a C9orf72 mutation is characterized by two distinct types of characteristic protein depositions containing either TDP-43 or so-called dipeptide repeat proteins that extend beyond frontal and temporal regions. Thalamus and cerebellum seem to be preferentially affected by the dipeptide repeat pathology unique to C9orf72 mutation carriers. Objective: This study aimed to determine if mutation carriers showed an enhanced degree of thalamic and cerebellar atrophy compared to sporadic patients or healthy controls. Methods: Atlas-based volumetry was performed in 13 affected C9orf72 FTD, ALS and FTD/ALS patients, 45 sporadic FTD and FTD/ALS patients and 19 healthy controls. Volumes and laterality indices showing significant differences between mutation carriers and sporadic patients were subjected to binary logistic regression to determine the best predictor of mutation carrier status. Results: Compared to sporadic patients, mutation carriers showed a significant volume reduction of the thalamus, which was most striking in the occipital, temporal and prefrontal subregion of the thalamus. Disease severity measured by mini mental status examination (MMSE) and FTD modified Clinical Dementia Rating Scale Sum of Boxes (FTD-CDR-SOB) significantly correlated with volume reduction in the aforementioned thalamic subregions. No significant atrophy of cerebellar regions could be detected. A logistic regression model using the volume of the prefrontal and the laterality index of the occipital subregion of the thalamus as predictor variables resulted in an area under the curve (AUC) of 0.88 while a model using overall thalamic volume still resulted in an AUC of 0.82. Conclusion: Our data show that thalamic atrophy in C9orf72 mutation carriers goes beyond the expected atrophy in the prefrontal and temporal subregion and is in good agreement with the cortical atrophy pattern described in C9orf72 mutation carriers, indicating a retrograde degeneration of functionally connected regions. Clinical relevance of the detected thalamic atrophy is illustrated by a correlation with disease severity. Furthermore, the findings suggest MRI volumetry of the thalamus to be of high predictive value in differentiating C9orf72 mutation carriers from patients with sporadic FTD.

ID: 29889265
Title: Systematic Screening of Ubiquitin/p62 Aggregates in Cerebellar Cortex Expands the Neuropathological Phenotype of the C9orf72 Expansion Mutation.
Abstract: The neuropathological hallmark of the C9orf72 intronic hexanucleotide expansion in frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) is the presence of small ubiquitin/p62-positive and transactive response DNA binding protein 43 kDa (TDP-43)-negative cytoplasmic inclusions in several brain areas. The identification of this histopathological signature is highly predictive of an underlying mutation. In this study, we screened 1800 cases of the Barcelona IDIBAPS Brain Bank, independently of the clinical and final neuropathological diagnosis of the brain donor, for the presence of ubiquitin/p62-positive inclusions in the cerebellum (UPPI). Positive cases were also stained for dipeptide repeats. We identified a total of 21 donors with UPPI and in all of them the C9orf72 hexanucleotide expansion was genetically confirmed. Most donors had an FTLD or to a lesser extent ALS clinico-pathological phenotype. However, 3 cases had been previously classified as having clinically and neuropathologically Lewy body disease. Other co-existing pathologies, especially of the PART-type, were also frequently encountered. This study highlights the importance of the evaluation of ubiquitin/p62-positive cytoplasmic inclusions in all neurodegenerative diseases as a good screening method for the detection of C9orf72 expansion mutation, since this mutation is not rare and can overlap with other neurodegenerative entities.

ID: 34168085
Title: Genotype-associated cerebellar profiles in ALS: focal cerebellar pathology and cerebro-cerebellar connectivity alterations.
Abstract: Cerebellar disease burden and cerebro-cerebellar connectivity alterations are poorly characterised in amyotrophic lateral sclerosis (ALS) despite the likely contribution of cerebellar pathology to the clinical heterogeneity of the condition. A prospective imaging study has been undertaken with 271 participants to systematically evaluate cerebellar grey and white matter alterations, cerebellar peduncle integrity and cerebro-cerebellar connectivity in ALS. Participants were stratified into four groups: (1) patients testing positive for GGGGCC repeat expansions in C9orf72, (2) patients carrying an intermediate-length repeat expansion in ATXN2, (3) patients without established ALS-associated mutations and (4) healthy controls. Additionally, the cerebellar profile of a single patient with ALS who had an ATXN2 allele length of 62 was evaluated. Cortical thickness, grey matter and white matter volumes were calculated in each cerebellar lobule complemented by morphometric analyses to characterise genotype-associated atrophy patterns. A Bayesian segmentation algorithm was used for superior cerebellar peduncle volumetry. White matter diffusivity parameters were appraised both within the cerebellum and in the cerebellar peduncles. Cerebro-cerebellar connectivity was assessed using deterministic tractography. Cerebellar pathology was confined to lobules I-V of the anterior lobe in patients with sporadic ALS in contrast to the considerable posterior lobe and vermis disease burden identified in C9orf72 mutation carriers. Patients with intermediate ATXN2 expansions did not exhibit significant cerebellar pathology. Focal rather than global cerebellar degeneration characterises ALS. Pathognomonic ALS symptoms which are typically attributed to other anatomical regions, such as dysarthria, dysphagia, pseudobulbar affect, eye movement abnormalities and cognitive deficits, may be modulated, exacerbated or partially driven by cerebellar changes in ALS.

ID: 36982312
Title: Saliva and Saliva Extracellular Vesicles for Biomarker Candidate Identification-Assay Development and Pilot Study in Amyotrophic Lateral Sclerosis.
Abstract: Saliva is gaining increasing attention as a source of biomarkers due to non-invasive and undemanding collection access. Extracellular vesicles (EVs) are nano-sized, cell-released particles that contain molecular information about their parent cells. In this study, we developed methods for saliva biomarker candidate identification using EV-isolation and proteomic evaluation. We used pooled saliva samples for assay development. EVs were isolated using membrane affinity-based methods followed by their characterization using nanoparticle tracking analysis and transmission electron microscopy. Subsequently, both saliva and saliva-EVs were successfully analyzed using proximity extension assay and label-free quantitative proteomics. Saliva-EVs had a higher purity than plasma-EVs, based on the expression of EV-proteins and albumin. The developed methods could be used for the analysis of individual saliva samples from amyotrophic lateral sclerosis (ALS) patients and controls (n = 10 each). The starting volume ranged from 2.1 to 4.9 mL and the amount of total isolated EV-proteins ranged from 5.1 to 42.6 µg. Although no proteins were significantly differentially expressed between the two groups, there was a trend for a downregulation of ZNF428 in ALS-saliva-EVs and an upregulation of IGLL1 in ALS saliva. In conclusion, we have developed a robust workflow for saliva and saliva-EV analysis and demonstrated its technical feasibility for biomarker discovery.

ID: 37009460
Title: Retinal fingerprints of ALS in patients: Ganglion cell apoptosis and TDP-43/p62 misplacement.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neuron function. Although ophthalmic deficits are not considered a classic symptom of ALS, recent studies suggest that changes in retinal cells, similar to those in the spinal cord motor neurons, have been observed in postmortem human tissues and animal models. In this study, we examined by immunofluorescence analysis the retinal cell layers of sporadic ALS patients in post-mortem retinal slices. We evaluated the presence of cytoplasmic TDP-43 and SQSTM1/p62 aggregates, activation of the apoptotic pathway, and microglia and astrocytes reactivity. We found in the retinal ganglion cell layer of ALS patients the increase of mislocalized TDP-43, SQSTM1/p62 aggregates, activation of cleaved caspase-3, and microglia density, suggesting that retinal changes can be used as an additional diagnostic tool for ALS. The retina is considered part of the central nervous system, and neurodegenerative changes in the brain may be accompanied by structural and possibly functional changes in the neuroretina and ocular vasculature. Therefore, using in vivo retinal biomarkers as an additional diagnostic tool for ALS may provide an opportunity to longitudinally monitor individuals and therapies over time in a noninvasive and cost-effective manner.

ID: 37816685
Title: Poly-GA immunohistochemistry is a reliable tool for detecting C9orf72 hexanucleotide repeat expansions.
Abstract: Poly-GA immunohistochemistry (A) on formalin fixed paraffin embedded cerebellum sections shows a similar distribution to p62 antibody (B) and reliably identifies neuronal cytoplasmic inclusions and neurites in cases with known C9orf72 repeat expansion. This is useful in the research setting where genetic testing has not been performed in life or suitable tissue is not avilable post-mortem.

ID: 38641715
Title: Abundant transcriptomic alterations in the human cerebellum of patients with a C9orf72 repeat expansion.
Abstract: The most prominent genetic cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) is a repeat expansion in the gene C9orf72. Importantly, the transcriptomic consequences of the C9orf72 repeat expansion remain largely unclear. Here, we used short-read RNA sequencing (RNAseq) to profile the cerebellar transcriptome, detecting alterations in patients with a C9orf72 repeat expansion. We focused on the cerebellum, since key C9orf72-related pathologies are abundant in this neuroanatomical region, yet TDP-43 pathology and neuronal loss are minimal. Consistent with previous work, we showed a reduction in the expression of the C9orf72 gene and an elevation in homeobox genes, when comparing patients with the expansion to both patients without the C9orf72 repeat expansion and control subjects. Interestingly, we identified more than 1000 alternative splicing events, including 4 in genes previously associated with ALS and/or FTLD. We also found an increase of cryptic splicing in C9orf72 patients compared to patients without the expansion and controls. Furthermore, we demonstrated that the expression level of select RNA-binding proteins is associated with cryptic splice junction inclusion. Overall, this study explores the presence of widespread transcriptomic changes in the cerebellum, a region not confounded by severe neurodegeneration, in post-mortem tissue from C9orf72 patients.

ID: 38927130
Title: Shotgun Proteomics Links Proteoglycan-4+ Extracellular Vesicles to Cognitive Protection in Amyotrophic Lateral Sclerosis.
Abstract: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder lacking reliable biomarkers for early diagnosis and disease progression monitoring. This study aimed to identify the novel biomarkers in plasmatic extracellular vesicles (EVs) isolated from ALS patients and healthy controls (HCs). A total of 61 ALS patients and 30 age-matched HCs were enrolled in the study and the protein content of circulating EVs was analyzed by shotgun proteomics. The study was divided into a discovery phase (involving 12 ALS and 12 HC patients) and a validation one (involving 49 ALS and 20 HC patients). In the discovery phase, more than 300 proteins were identified, with 32 proteins showing differential regulation in ALS patients compared to HCs. In the validation phase, over 400 proteins were identified, with 20 demonstrating differential regulation in ALS patients compared to HCs. Notably, seven proteins were found to be common to both phases, all of which were significantly upregulated in EVs from ALS patients. Most of them have previously been linked to ALS since they have been detected in the serum or cerebrospinal fluid of ALS patients. Among them, proteoglycan (PRG)-4, also known as lubricin, was of particular interest since it was significantly increased in ALS patients with normal cognitive and motor functions. This study highlights the significance of EVs as a promising avenue for biomarker discovery in ALS. Moreover, it sheds light on the unexpected role of PRG-4 in relation to cognitive status in ALS patients.

ID: 39709457
Title: CHMP2B promotes CHMP7 mediated nuclear pore complex injury in sporadic ALS.
Abstract: Alterations to the composition and function of neuronal nuclear pore complexes (NPCs) have been documented in multiple neurodegenerative diseases including Amyotrophic Lateral Sclerosis (ALS). Moreover, recent work has suggested that injury to the NPC can at least in part contribute to TDP-43 loss of function and mislocalization, a pathological hallmark of ALS and related neurodegenerative diseases. Collectively, these studies highlight a role for disruptions in NPC homeostasis and surveillance as a significant pathophysiologic event in neurodegeneration. The ESCRT-III nuclear surveillance pathway plays a critical role in the surveillance and maintenance of NPCs and the surrounding nuclear environment. Importantly, pathologic alterations to this pathway and its protein constituents have been implicated in neurodegenerative diseases such as ALS. However, the mechanism by which this pathway contributes to disease associated alterations in the NPC remains unknown. Here we use an induced pluripotent stem cell (iPSC) derived neuron (iPSN) model of sALS to demonstrate that CHMP7/ESCRT-III nuclear maintenance/surveillance is overactivated in sALS neurons. This overactivation is dependent upon the ESCRT-III protein CHMP2B and sustained CHMP2B dependent "activation" is sufficient to contribute to pathologic CHMP7 nuclear accumulation and POM121 reduction. Importantly, partial knockdown of CHMP2B was sufficient to alleviate NPC injury and downstream TDP-43 dysfunction in sALS neurons thereby highlighting CHMP2B as a potential therapeutic target in disease.

ID: 39986312
Title: Amyotrophic lateral sclerosis caused by hexanucleotide repeat expansions in C9orf72: from genetics to therapeutics.
Abstract: GGGGCC repeat expansions in C9orf72 are a common genetic cause of amyotrophic lateral sclerosis in people of European ancestry; however, substantial variability in the penetrance of the mutation, age at disease onset, and clinical presentation can complicate diagnosis and prognosis. The repeat expansion is bidirectionally transcribed in the sense and antisense directions into repetitive RNAs and translated into dipeptide repeat proteins, and both accumulate in the cortex, cerebellum, and the spinal cord. Furthermore, neuropathological aggregates of phosphorylated TDP-43 are observed in motor cortex and other cortical regions, and in the spinal cord of patients at autopsy. C9orf72 repeat expansions can also cause frontotemporal dementia. The GGGGCC repeat induces a complex interplay of loss-of-function and gain-of-function pathological mechanisms. Clinical trials using antisense oligonucleotides to target the GGGGCC repeat RNA have not been successful, potentially because they only target a single gain-of-function mechanism. Novel therapeutic approaches targeting the DNA repeat expansion, multiple repeat-derived RNA species, or downstream targets of TDP-43 dysfunction are, however, on the horizon, together with the development of diagnostic and prognostic biomarkers.

ID: 40275359
Title: Multi-region brain transcriptomic analysis of amyotrophic lateral sclerosis reveals widespread RNA alterations and substantial cerebellum involvement.
Abstract: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that primarily affects the motor neurons, causing progressive muscle weakness and paralysis. While research has focused on understanding pathological mechanisms in the motor cortex and spinal cord, there is growing evidence that extra-motor brain regions may also play a role in the pathogenesis or progression of ALS. We generated 165 sample-matched post-mortem brain transcriptomes from 22 sporadic ALS patients with pTDP-43 pathological staging and 11 non-neurological controls. For each individual, five brain regions underwent mRNA sequencing: motor cortex (pTDP-43 inclusions always present), prefrontal cortex and hippocampus (pTDP-43 inclusions sometimes present), and occipital cortex and cerebellum (pTDP-43 inclusions rarely present). We examined gene expression, cell-type composition, transcript usage (% contribution of a transcript to total gene expression) and alternative splicing, comparing ALS-specific changes between brain regions. We also considered whether post-mortem pTDP-43 pathological stage classification defined ALS subgroups with distinct gene expression profiles. Significant gene expression changes were observed in ALS cases for all five brain regions, with the cerebellum demonstrating the largest number of total (> 3,000) and unique (60%) differentially expressed genes. Pathway enrichment and predicted activity were largely concordant across brain regions, suggesting that ALS-linked mechanisms, including inflammation, mitochondrial dysfunction and oxidative stress, are also dysregulated in non-motor brain regions. Switches in transcript usage were identified for a small set of genes including increased usage of a POLDIP3 transcript, associated with TDP-43 loss-of-function, in the cerebellum and a XBP1 transcript, indicative of unfolded protein response activity, in the motor cortex. Extensive variation in RNA splicing was identified in the ALS brain, with 26-41% of alternatively spliced genes unique to a given brain region. This included detection of TDP-43-associated cryptic splicing events such as the STMN2 cryptic exon which was shown to have a pTDP-43 pathology-specific expression pattern. Finally, ALS patients with stage 4 pTDP-43 pathology demonstrated distinct gene and protein expression changes in the cerebellum. Together our findings highlighted widespread transcriptome alterations in ALS post-mortem brain and showed that, despite the absence of pTDP-43 pathology in the cerebellum, extensive and pTDP-43 pathological stage-specific RNA changes are evident in this brain region.

ID: 40283201
Title: Pathophysiology, Clinical Heterogeneity, and Therapeutic Advances in Amyotrophic Lateral Sclerosis: A Comprehensive Review of Molecular Mechanisms, Diagnostic Challenges, and Multidisciplinary Management Strategies.
Abstract: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons, leading to muscle atrophy, paralysis, and respiratory failure. This comprehensive review synthesizes the current knowledge on ALS pathophysiology, clinical heterogeneity, diagnostic frameworks, and evolving therapeutic strategies. Mechanistically, ALS arises from complex interactions between genetic mutations (e.g., in C9orf72, SOD1, TARDBP (TDP-43), and FUS) and dysregulated cellular pathways, including impaired RNA metabolism, protein misfolding, nucleocytoplasmic transport defects, and prion-like propagation of toxic aggregates. Phenotypic heterogeneity, manifesting as bulbar-, spinal-, or respiratory-onset variants, complicates its early diagnosis, which thus necessitates the rigorous application of the revised El Escorial criteria and emerging biomarkers such as neurofilament light chain. Clinically, ALS intersects with frontotemporal dementia (FTD) in up to 50% of the cases, driven by shared TDP-43 pathology and C9orf72 hexanucleotide expansions. Epidemiological studies have revealed a lifetime risk of 1:350, with male predominance (1.5:1) and peak onset between 50 and 70 years. Disease progression varies widely, with a median survival of 2-4 years post-diagnosis, underscoring the urgency for early intervention. Approved therapies, including riluzole (glutamate modulation), edaravone (antioxidant), and tofersen (antisense oligonucleotide), offer modest survival benefits, while dextromethorphan/quinidine alleviates the pseudobulbar affect. Non-pharmacological treatment advances, such as non-invasive ventilation (NIV), prolong survival by 13 months and improve quality of life, particularly in bulb-involved patients. Multidisciplinary care-integrating physical therapy, respiratory support, nutritional management, and cognitive assessments-is critical to addressing motor and non-motor symptoms (e.g., dysphagia, spasticity, sleep disturbances). Emerging therapies show promise in preclinical models. However, challenges persist in translating genetic insights into universally effective treatments. Ethical considerations, including euthanasia and end-of-life decision-making, further highlight the need for patient-centered communication and palliative strategies.

ID: 40287755
Title: TDP-43 seeding activity in the olfactory mucosa of patients with amyotrophic lateral sclerosis.
Abstract: In recent years, the seed amplification assay (SAA) has enabled the identification of pathological TDP-43 in the cerebrospinal fluid (CSF) and olfactory mucosa (OM) of patients with genetic forms of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Here, we investigated the seeding activity of TDP-43 in OM samples collected from patients with sporadic ALS. OM samples were collected from patients with (a) sporadic motor neuron diseases (MND), including spinal ALS (n = 35), bulbar ALS (n = 18), primary lateral sclerosis (n = 10), and facial onset sensory and motor neuronopathy (n = 2); (b) genetic MND, including carriers of C9orf72exp (n = 6), TARDBP (n = 4), SQSTM1 (n = 3), C9orf72exp + SQSTM1 (n = 1), OPTN (n = 1), GLE1 (n = 1), FUS (n = 1) and SOD1 (n = 4) mutations; (c) other neurodegenerative disorders (OND), including Alzheimer's disease (n = 3), dementia with Lewy bodies (n = 8) and multiple system atrophy (n = 6); and (d) control subjects (n = 22). All samples were subjected to SAA analysis for TDP-43 (TDP-43_SAA). Plasmatic levels of TDP-43 and neurofilament-light chain (NfL) were also assessed in a selected number of patients. TDP-43_SAA was positive in 29/65 patients with sporadic MND, 9/21 patients with genetic MND, 6/17 OND patients and 3/22 controls. Surprisingly, one presymptomatic individual also tested positive. As expected, OM of genetic non-TDP-43-related MND tested negative. Interestingly, fluorescence values from non-MND samples that tested positive were consistently and significantly lower than those obtained with sporadic and genetic MND. Furthermore, among TDP-43-positive samples, the lag phase observed in MND patients was significantly longer than that in non-MND patients. Plasma TDP-43 levels were significantly higher in sporadic MND patients compared to controls and decreased as the disease progressed. Similarly, plasma NfL levels were higher in both sporadic and genetic MND patients and positively correlated with disease progression rate (ΔFS). No significant correlations were detected between TDP-43_SAA findings and the biological, clinical, or neuropsychological parameters considered. The OM of a subset of patients with sporadic MND can trigger seeding activity for TDP-43, as previously observed in genetic MND. Thus, TDP-43_SAA analysis of OM can improve the clinical characterization of ALS across different phenotypes and enhance our understanding of these diseases. Finally, plasma TDP-43 could serve as a potential biomarker for monitoring disease progression. However, further research is needed to confirm and expand these findings.

ID: 40619440
Title: Methylome analysis of FTLD patients with TDP-43 pathology identifies epigenetic signatures specific to pathological subtypes.
Abstract: In the last decade, the importance of DNA methylation in the functioning of the central nervous system has been highlighted through associations between methylation changes and differential expression of key genes involved in aging and neurodegenerative diseases. In frontotemporal lobar degeneration (FTLD), aberrant methylation has been reported in causal disease genes including GRN and C9orf72; however, the genome-wide contribution of epigenetic changes to the development of FTLD remains largely unexplored. We performed reduced representation bisulfite sequencing of matched pairs of post-mortem tissue from frontal cortex (FCX) and cerebellum (CER) from pathologically confirmed FTLD patients with TDP-43 pathology (FTLD-TDP) further divided into five subtypes and including both sporadic and genetic forms (N = 25 pairs per group), and neuropathologically normal controls (N = 42 pairs). Case-control differential methylation analyses were performed, both at the individual CpG level, and in regions of grouped CpGs (differentially methylated regions; DMRs), either including all genomic locations or only gene promoters. Gene Ontology (GO) analyses were then performed using all differentially methylated genes in each group of sporadic patients. Finally, additional datasets were queried to prioritize candidate genes for follow-up. Using the largest FTLD-TDP DNA methylation dataset generated to date, we identified thousands of differentially methylated CpGs (FCX = 6,520; CER = 7,134) and several hundred DMRs in FTLD-TDP brains (FCX = 134; CER = 219). Of these, less than 10% are shared between pathological subgroups. Combining additional datasets, we identified, validated and replicated hypomethylation of CAMTA1 in TDP-A potentially also impacting additional genes in the locus. GO analysis further implicated DNA methylation in myelination and developmental processes, as well as important disease-relevant mechanisms with subtype specificity such as protein phosphorylation and DNA damage repair in TDP-A, cholesterol biosynthesis in TDP-B, and protein localization in TDP-C. We identify methylation changes in all FTLD-TDP patient groups and show that most changes are unique to a specific pathological FTLD-TDP subtype, suggesting that these subtypes not only have distinct transcriptomic and genetic signatures, but are also epigenetically distinct. Our study constitutes an invaluable resource to the community and highlights the need for further studies to profile additional epigenetic layers within each FTLD-TDP pathological subtype.

ID: 40625857
Title: A Novel Retinal Nerve Fiber Layer Biomarker of Amyotrophic Lateral Sclerosis (ALS) Identified Using Longitudinal in vivo Ocular Imaging.
Abstract: Like motor neurons, retinal ganglion cells (RGCs) have long axons and high metabolic demands, making them vulnerable to disruption of axonal transport. Unlike motor neurons, the RGC axons are accessible to high-resolution non-invasive optical imaging in their intraocular portion. A non-invasive in vivo retinal imaging biomarker can be valuable for amyotrophic lateral sclerosis (ALS) diagnosis and monitoring. We aim to assess the presence of inner retinal pathology in a mouse model of ALS and its possible progression with age. Transgenic SOD1G93A mice (n=8, 4M/4F) and age-matched controls (n=8, 4M/4F) underwent in vivo retinal imaging with confocal scanning laser ophthalmoscopy (cSLO) coupled with optical coherence tomography (OCT) at 20 weeks of age. Another group of SOD1G93A mice (n=20, 6M/14F) and age-matched controls (n=20, 6M/14F) underwent longitudinal in vivo retinal imaging with the same device. Each retinal imaging session included infrared reflectance (IR) and blue reflectance (BR) cSLO coupled with OCT. Hyperreflective puncta located in the retinal nerve fiber layer (RNFL) were counted in a blinded fashion in ALS and control mice. The number of puncta at 20 weeks of age in ALS mice was compared with controls using Wilcoxon test. The rates of increase of puncta number were analyzed using a Generalized Linear Mixed-Effect Model (GLMM) for genotype, time, and sex. IR-cSLO coupled with OCT revealed hyperreflective puncta located in the RNFL of ALS mice. IR-cSLO fundus imaging at the age of 20 weeks showed ALS mice had significantly higher number of puncta compared to controls (2.1±2.3 vs 0.5±0.8; (mean±SD), respectively, p=0.036). GLMM analysis showed both ALS mutation and age were significantly associated with the rate of increase of puncta number (p=0.000232 and p=0.000366, respectively). In addition, female ALS mice had a steeper increase of puncta compared to male ALS mice (0.21±0.04 log number puncta/week vs 0.16±0.04, respectively; p=0.037). Our findings demonstrate distinct inner retinal nerve fiber layer pathology, detected using cSLO coupled with OCT, which worsens over time. These findings support the potential of retinal imaging as a translationally relevant, non-invasive biomarker for ALS diagnosis or disease monitoring in humans.

ID: 40665048
Title: The Global Neurodegeneration Proteomics Consortium: biomarker and drug target discovery for common neurodegenerative diseases and aging.
Abstract: More than 57 million people globally suffer from neurodegenerative diseases, a figure expected to double every 20 years. Despite this growing burden, there are currently no cures, and treatment options remain limited due to disease heterogeneity, prolonged preclinical and prodromal phases, poor understanding of disease mechanisms, and diagnostic challenges. Identifying novel biomarkers is crucial for improving early detection, prognosis, staging and subtyping of these conditions. High-dimensional molecular studies in biofluids ('omics') offer promise for scalable biomarker discovery, but challenges in assembling large, diverse datasets hinder progress. To address this, the Global Neurodegeneration Proteomics Consortium (GNPC)-a public-private partnership-established one of the world's largest harmonized proteomic datasets. It includes approximately 250 million unique protein measurements from multiple platforms from more than 35,000 biofluid samples (plasma, serum and cerebrospinal fluid) contributed by 23 partners, alongside associated clinical data spanning Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). This dataset is accessible to GNPC members via the Alzheimer's Disease Data Initiative's AD Workbench, a secure cloud-based environment, and will be available to the wider research community on 15 July 2025. Here we present summary analyses of the plasma proteome revealing disease-specific differential protein abundance and transdiagnostic proteomic signatures of clinical severity. Furthermore, we describe a robust plasma proteomic signature of APOE ε4 carriership, reproducible across AD, PD, FTD and ALS, as well as distinct patterns of organ aging across these conditions. This work demonstrates the power of international collaboration, data sharing and open science to accelerate discovery in neurodegeneration research.

ID: 40698100
Title: Ganglion Cell Layer Thickness as a Biomarker for Amyotrophic Lateral Sclerosis Functional Outcome: An OCT study.
Abstract: This study aims to evaluate various optical coherence tomography (OCT) parameters in patients diagnosed with amyotrophic lateral sclerosis (ALS). Assessment of BCVA was done using Snellen charts, and subjective refraction was done to achieve a BCVA for distance and near. Measurement of intraocular pressure (IOP) was done with Goldman applanation tonometry. Stereoscopic fundus examination was performed using a 90D lens to assess the status of the optic nerve and retina, ruling out any ocular pathology. The patients were then subjected to OCT scanning to measure optic nerve head and macular parameters. Optical coherence tomography was performed using CIRRUS™ HD OCT (500-21822) (version 8.0.0.518) (Carl Zeiss Meditec, Dublin, CA, USA). The analyzed area was centered manually, and the absence of segmentation errors was confirmed for each scan. RE Avg RNFL and LE Avg RNFL showed weak correlations with ALSFRS, indicated by Pearson Correlation coefficients of 0.073 and -0.026, respectively. The p-values (0.637 and 0.86) suggested that these correlations were not statistically significant. RE Avg GCL and LE Avg GCL, on the other hand, exhibited moderate positive correlations with ALSFRS scores, with correlation coefficients of 0.337 (RE) and 0.389 (LE). These correlations were statistically significant, as indicated by p-values of 0.021 and 0.006, respectively, suggesting a substantial association between GCL thickness and ALS functional outcomes. All patients in our study were clinically diagnosed cases of ALS, as per the El Escorial criteria. Age group-wise analysis showed statistically significant thinning overall as well as quadrant-wise RNFL parameters in patients less than 50 years compared to age-matched controls, indicating that the pathological process occurring in larger motor neurons in ALS might also be happening in smaller sensory neurons of the retina, causing thinning, which was not due to age-related process. Although GCIPL thinning was occurring in our cases, though statistically not significant compared to control, the significant positive correlation observed between GCIPL and ALS functional outcome and between RNFL and GCIPL measurements highlighted the fact that though the axonal degeneration in retinal neurons might not be translating to the same extent in ganglion cells in ALS, the subtle thinning of GCIPL correlated strongly with functional disability in patients with ALS, implying better functional scores with higher values of GCIPL parameters. In summary, GCL measurements in both eyes showed a notable relationship with ALSFRS, whereas RNFL did not appear to correlate significantly.

ID: 40753166
Title: Sporadic ALS induced pluripotent stem cell derived neurons reveal hallmarks of TDP-43 loss of function.
Abstract: Nuclear loss and cytoplasmic buildup of the RNA-binding protein TDP-43 is a hallmark of ALS and related disorders. While studies using artificial TDP-43 depletion in neurons have revealed changes in gene expression and splicing, their relevance to actual patients remained unclear. Induced pluripotent stem cell (iPSC)-derived neurons (iPSNs) from 180 individuals, including controls, C9orf72 ALS/FTD, and sporadic ALS (sALS) patients were used to generate and analyze ~32,500 qRT-PCR data points across 20 genes which identified variable, time-dependent signatures of TDP-43 loss of function in individual lines. Notably, the same changes were also seen in postmortem brain tissue from the same patients, confirming that iPSNs accurately model disease. Inducing damage to the nuclear pore complex, specifically by reducing the nucleoporin POM121 in healthy iPSNs, was enough to replicate the molecular changes associated with ALS/FTD TDP-43 dysfunction. This directly links nuclear pore integrity to TDP-43-related pathology. Encouragingly, repairing nuclear pore injury in sALS iPSNs restored normal gene processing disrupted by TDP-43 loss. This study (1) provides a valuable population-scale resource for studying TDP-43 dysfunction in ALS, (2) confirms that patient-derived iPSNs closely reflect disease processes seen in the brain, and (3) demonstrates that targeting nuclear pore injury may offer a promising therapeutic strategy in ALS.

ID: 40794569
Title: Design considerations for C9orf72 disease prevention trials.
Abstract: The idea that it might be possible to prevent some forms of amyotrophic lateral sclerosis and frontotemporal dementia has finally come of age. The hexanucleotide repeat expansion in the C9orf72 gene accounts for ∼10% of all amyotrophic lateral sclerosis and 10%-15% of all frontotemporal dementia diagnoses, with the two clinical syndromes co-manifesting in a significant number of patients. As a result, clinically unaffected carriers of pathogenic C9orf72 repeat expansions are currently the largest identifiable population at significantly elevated risk for both amyotrophic lateral sclerosis and frontotemporal dementia, and in whom it might be possible to prevent the emergence of clinically manifest disease. Strategies for the design of disease prevention trials among clinically unaffected C9orf72 carriers have begun to emerge separately in the amyotrophic lateral sclerosis and frontotemporal dementia fields. However, recognition of the need to define neurodegenerative diseases based on biology underscores the need to consider all potential clinical manifestations of a C9orf72 repeat expansion together, rather than the traditional siloed approach of focusing on only amyotrophic lateral sclerosis or only frontotemporal dementia. Indeed, emerging clinical and biological markers that might be used to quantify pre-symptomatic disease progression and to predict the short-term risk of phenoconversion to clinically manifest disease are shared across the phenotypic spectrum. Given the anticipated progress in the development of therapeutic strategies to target the C9orf72 repeat expansion, and the enthusiasm for prevention trials among the unaffected C9orf72 repeat expansion carrier population, now is the time to begin work on the design of disease prevention trials. To this end, The Association for Frontotemporal Degeneration and The ALS Association supported a multi-stakeholder workshop (in Washington D.C., June 2024) to unify efforts to design a prevention trial for the population at elevated genetic risk for the phenotypic spectrum of C9orf72 disease. Here we describe recommendations emanating from this workshop for the selection of outcome measures, delineation of eligibility criteria, optimal use of biomarkers and digital health technologies, potential analytic frameworks and relevant regulatory considerations related to C9orf72 disease prevention trials. We also emphasize the importance of the amyotrophic lateral sclerosis and frontotemporal dementia communities working together in partnership with the C9orf72 repeat expansion carrier community, the regulatory authorities and the broader drug development community.

ID: 40832743
Title: Neurochemical biomarkers of amyotrophic lateral sclerosis: recent developments.
Abstract: To provide an overview of the recent developments in the field of neurochemical biomarkers of amyotrophic lateral sclerosis (ALS). Neurofilaments, especially NFL, have been confirmed to be good biomarkers for ALS. NFL may be diagnostically useful but its main role is as prognostic and pharmacodynamic biomarker. Inflammatory biomarkers, especially the chitinases, might also serve as pharmacodynamic biomarkers in treatment trials targeting neuroinflammation. GFAP could reflect cognitive-behavioural impairment. CSF dipeptides are diagnostic biomarkers for ALS caused by the C9ORF72 exanucleotide repeat expansion and may be used to confirm target engagement by experimental drugs. Levels of TDP-43 (virtually the ideal biomarker for ALS) in CSF and plasma have not been demonstrated to be consistently altered in ALS. However, promising advancements have been achieved in seed amplification assays for the protein, in its quantification in plasma extracellular vesicles, and in the measurement of CSF levels of a protein reflecting splicing dysfunction of TDP-43. Finally, blood phosphorylated tau has emerged as an ALS biomarker linked to lower motor neuron (or muscle) pathology. NFL is still the best neurochemical biomarker for ALS. However, substantial advances have been recently made, especially regarding detection of TDP-43 and blood phosphorylated tau.

ID: 40898360
Title: Identification and validation of a tear fluid-derived protein biomarker signature in patients with amyotrophic lateral sclerosis.
Abstract: The diagnosis of Amyotrophic Lateral Sclerosis (ALS) remains challenging, particularly in early stages, where characteristic symptoms may be subtle and nonspecific. The development of disease-specific and clinically validated biomarkers is crucial to optimize diagnosis. Here, we explored tear fluid (TF) as a promising ALS biomarker source, given its accessibility, anatomical proximity to the brainstem as an important site of neurodegeneration, and proven discriminative power in other neurodegenerative diseases. Using a discovery approach, we profiled protein abundance in TF of ALS patients (n = 49) and controls (n = 54) via data-independent acquisition mass spectrometry. Biostatistical analysis and machine learning identified differential protein abundance and pathways in ALS, leading to a protein signature. These proteins were validated by Western blot in an independent cohort (ALS n = 51; controls n = 52), and their discriminatory performance was assessed in-silico employing machine learning. 876 proteins were consistently detected in TF, with 106 differentially abundant in ALS. A six-protein signature, including CRYM, PFKL, CAPZA2, ALDH16A1, SERPINC1, and HP, exhibited discriminatory potential. We replicated significant differences of SERPINC1 and HP levels between ALS and controls across the cohorts, and their combination yielded the best in-silico performance. Overall, this investigation of TF proteomics in ALS and controls revealed dysregulated proteins and pathways, highlighting inflammation as a key disease feature, strengthening the potential of TF as a source for biomarker discovery.

ID: 40908789
Title: Genotype-specific interferon signatures in amyotrophic lateral sclerosis relate to disease severity.
Abstract: Innate immune signalling pathways are hyperactivated in the CNS of patients with amyotrophic lateral sclerosis (ALS), as well as in preclinical models with diverse causative backgrounds including TDP-43, SOD1 and C9orf72 mutations. This raises an important question of whether these pathways are key pathogenic features of the disease, and whether therapeutic amelioration could be beneficial. Here, we systematically profile type-I interferon (IFN)-stimulated gene (ISG) expression signatures using a non-biased approach in CNS tissue from a cohort of 36 individuals with ALS, including sporadic ALS (sALS; n = 18), genetic ALS caused by: (i) a C9orf72 hexanucleotide repeat expansion (C9-ALS; n = 11); and (ii) a SOD1 mutation (SOD1-ALS; n = 5), alongside age- and sex-matched individuals who died of a non-neurological cause (n = 12). Using this deeply phenotyped cohort we have implemented targeted transcriptomic analysis and immunohistochemistry to interrogate the nature and extent of the activation of the type-I IFN response in patients. We determined disease- and genotype-specific IFN signatures that correlate with clinical phenotype. Correlation analysis linked six ISGs with aggressive disease progression, as indicated by negative correlation with age at death in ALS patients. Notably, significant upregulation of ISGs was observed in C9-ALS patients, with higher ISG expression correlating with shorter disease duration. Noting that our genotype- and disease-specific signatures correlated with metrics of disease progression, we explored the therapeutic potential of targeting this pathway in a mouse model of ALS. Treatment with an IFN pathway inhibitor reduced IFN response markers, delayed disease progression, including motor decline, and extended survival in ALS mice. We conclude that upregulation of gene expression in the type-I IFN pathway represents a key pathological feature of ALS and that inhibiting this pathway may provide a promising therapeutic approach for treating ALS.

ID: 40910231
Title: A Decade of Research on C9orf72 in Frontotemporal Dementia (2014-2024): A Bibliometric Analysis of Global Trends and Hotspots.
Abstract: Frontotemporal dementia (FTD) is the third most frequent dementia and the leading dementia subtype in individuals under 65. The discovery of C9orf72 (chromosome 9 open reading frame 72) GGGGCC abnormal expansion is a major genetic cause of both FTD and amyotrophic lateral sclerosis (ALS), linking these diseases along a clinicopathological spectrum. This study aimed to depict the research landscape of C9orf72 in FTD over the past decade, track emerging research hotspots, and provide insights into under-researched areas. Based on the Web of Science database, a bibliometric analysis was conducted to explore publication trends, key contributors, funding sources, journal categories, co-authorship networks, and keyword co-occurrence, clustering, and bursts. A total of 1,220 articles were identified, with sustained output of over 100 articles annually. The majority of contributions and funding support came from North America and Europe. Hot research themes included hexanucleotide repeats, nucleocytoplasmic transport, disease mechanisms, and therapeutic targets. North America and Europe were highly productive, supported by higher regional prevalence, genetic burden, and robust funding. Ploy-GR in cerebrospinal fluid has emerged as a diagnostic biomarker. Pathogenic mechanisms remain complex, involving both gain- and loss-of-function effects. Metformin and antisense oligonucleotides were considered as potential therapeutics. Further research is needed in underrepresented populations and on the translational potential of emerging molecular targets. This study offers a comprehensive overview of current trends and future directions over the past decade in C9orf72-related FTD research, allowing researchers-particularly those new to the area-to quickly understand the current landscape.

ID: 41061670
Title: A next-generation HDAC6 inhibitor for amyotrophic lateral sclerosis and frontotemporal dementia.
Abstract: Dysregulated proteostasis and intracellular transport contribute to neurodegeneration. Histone deacetylase 6 (HDAC6), a therapeutic target of interest for neurodegenerative diseases, acts at a nexus modulating both proteostasis and intracellular transport. Inhibition of HDAC6 deacetylase activity promotes autophagic clearance of protein aggregates and increases α-tubulin acetylation, thereby enhancing microtubule resiliency and motor protein-microtubule binding, which facilitates intracellular transport and, subsequently, proteostasis. Despite these benefits, advancement of HDAC6 inhibitor therapeutics for neurodegenerative disease has been hindered by inadequate selectivity and CNS-penetrance of first-generation compounds. Here, we characterize a next-generation small molecule HDAC6 inhibitor, EKZ-438, in preclinical models of amyotrophic lateral sclerosis and frontotemporal dementia. We present the pharmacological properties of EKZ-438, which demonstrate high selectivity for HDAC6 (>8500-fold selectivity for HDAC6 versus all other HDAC6 paralogues), low nanomolar potency (12 nM) for HDAC6, and importantly, CNS-penetrance (unbound brain-to-plasma partition coefficient [Kp,uu,brain] ≥ 0.55) and high oral bioavailability (fraction of dose absorbed [F%] = 70). In complementary preclinical in vitro and in vivo immunolabelling and live imaging studies we tested the hypothesis that selective inhibition of HDAC6 deacetylase activity is sufficient to improve pathophysiological proteostasis and intracellular transport deficits in animal models of familial and sporadic amyotrophic lateral sclerosis and frontotemporal dementia. Notably, we extended these findings to human induced pluripotent stem cell-derived neuronal cellular models, supporting the relevance of our findings to human disease. EKZ-438 treatment rescued superoxide dismutase 1 (SOD1) (q < 0.0001) and transactive response DNA binding protein 43 kDa (TDP-43) (q < 0.001) proteostasis defects following an excitotoxic glutamate challenge, and increased survival of SOD1G93A and wild-type motor neurons by 59% (q < 0.0001) and 37% (q < 0.01), respectively, demonstrating in vitro neuroprotection. In SOD1G93A mice, EKZ-438 improved axonal transport by 16% (q < 0.05), motor performance by ∼40% (q < 0.05) and decreased plasma neurofilament light chain levels by 35% (q < 0.05), demonstrating in vivo neuroprotection. In a TDP-43 mouse model, EKZ-438 reduced TDP-43 pathology by ∼30% (q < 0.05) and neuroinflammation by ∼26% (q < 0.05) in the brain, supporting HDAC6 inhibition for sporadic amyotrophic lateral sclerosis and frontotemporal dementia. Furthermore, EKZ-438 treatment improved intracellular transport by 39% (q < 0.001), rescued cytoplasmic TDP-43 accumulation by 87% (q < 0.0001) and restored nuclear TDP-43 splicing activity (P < 0.05) in human TARDBP neurons. These mechanistic improvements aligned with nearly complete rescue of human TARDBP and C9orf72 mutant neuron survival (P < 0.0001). We conclude that selective HDAC6 inhibition represents a promising therapeutic approach for potential disease modification in amyotrophic lateral sclerosis and frontotemporal dementia.

ID: 41072625
Title: An in vivo PET/CT investigation of mitochondrial complex 1, sigma 1, and synaptic vesicle 2 A in patients with amyotrophic lateral sclerosis.
Abstract: Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disorder which pathology is still largely unclear. To perform an in vivo cross-sectional investigation of mitochondrial complex 1 (MC1), synaptic vesicle 2 A (SV2A), and sigma-1 receptor (S1R) expression in ALS patients using the PET radioligands [18F]BCPP-EF, [11C]UCB-J, and [11C]SA4503. Sixteen ALS patients (twelve males, mean age: 57.49 ± 12.08 years) and sixteen healthy controls underwent clinical assessment, MRI, and PET imaging with [18F]BCPP-EF, [11C]UCB-J, and [11C]SA4503. Patients were stratified based on disease the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) progression rate into slow, and moderate/fast progressors. Volume of distribution (VT) of predefined regions of interest, corrected for partial volume effects, was the primary outcome. Across the ALS cohort, [18F]BCPP-EF binding was reduced in the amygdala (-13.9 %, F = 4.938 p = 0.034). Moderate/fast progression ALS patients exhibited [18F]BCPP-EF binding loss in the hippocampus (-20.0 %), amygdala (-21.4 %), cerebellum (-19.5 %), insular cortex (-19.3 %), temporal lobe (-19.0 %), and anterior cingulate (-18.7 %) (all p < 0.05); and [11C]SA4503 binding loss in the caudate (-20.6 %), pallidus (-26.8 %), amygdala (-20.2 %), hippocampus (-17.4 %), insular cortex (-16.9 %), accumbens (-17.0 %), anterior cingulate (-16.4 %) and temporal lobe (-19.8 %) compared to controls (all p < 0.05). In moderate/fast progressors, [18F]BCPP-EF loss in the insular cortex, amygdala, anterior cingulate, and temporal lobe correlated with lower ALSFRS-R scores (p < 0.05). Our findings reveal loss of MC1 and S1R in ALS, suggesting mitochondrial dysfunction associated with disease progression. This work provides initial insights of mitochondrial and receptor pathology in ALS, potentially guiding future biomarker development and therapeutic interventions.

ID: 41188870
Title: M102 activates both NRF2 and HSF1 transcription factor pathways and is neuroprotective in cell and animal models of amyotrophic lateral sclerosis.
Abstract: M102 is a central nervous system (CNS) penetrant small molecule electrophile which activates in vivo the NF-E2 p45-related factor 2-antioxidant response element (NRF2-ARE) pathway, as well as transcription of heat-shock element (HSE) associated genes. In the TDP-43Q331K transgenic mouse model of ALS dosed subcutaneously at 5 mg/kg OD or 2.5 mg/kg BD with M102, significant improvements in compound muscle action potential (CMAP) amplitude of hind limb muscles and gait parameters were observed at 6 months of age, with associated target engagement. An oral dose response study of M102 in SOD1G93A transgenic mice showed a dose-dependent improvement in CMAP of hindlimb muscles which correlated with preservation of lumbar spinal motor neurons at the same time point. These data enabled prediction of human efficacious exposures and doses, which were well within the safety margin predicted from Good Laboratory Practice (GLP) toxicology studies. A parallel program of work in vitro showed that M102 rescued motor neuron survival in co-culture with patient-derived astrocytes from sporadic, C9orf72 and SOD1 ALS cases. Markers of oxidative stress, as well as indices of TDP-43 proteinopathy were also reduced by exposure to M102 in these in vitro models. This comprehensive package of preclinical efficacy data across two mouse models as well as patient-derived astrocyte toxicity assays, provides a strong rationale for clinical evaluation of M102 in ALS patients. Combined with the development of target engagement biomarkers and the completed preclinical toxicology package, a clear translational pathway to testing in ALS patients has been developed.

ID: 41249720
Title: Role of 2-[18F]FDG-PET as a biomarker of upper motor neuron involvement in amyotrophic lateral sclerosis.
Abstract: Amyotrophic Lateral Sclerosis (ALS) affects upper (UMN) and lower (LMN) motor neurons. ALS diagnosis is challenging, especially in predominant LMN phenotypes. Electromyography can disclose LMN damage, while UMN involvement is detectable by clinical examination, with possible support of magnetic resonance imaging (MRI) and transcranial magnetic stimulation. Our aim was to investigate the role of 2-[18F]FDG-PET as an UMN biomarker in ALS. In our cross-sectional study, we created an UMN burden score. Performing a multiple regression analysis in SPM12, we evaluated the relationship between UMNBS and brain metabolism. We split ALS cohort based on the UMN burden score median value (group A-under median, group B-above median). We ran a full factorial analysis including group A and B and healthy controls, followed by group comparisons. We included 118 ALS patients (group A and B, N = 59), with a median UMN burden score of 9.50 and a left lateralization of UMN signs. We found a negative correlation between motor cortex metabolism and UMN burden score. Comparing each ALS group with healthy controls, we found relative hypometabolism in the left frontal lobe and relative bilateral, right-prevalent hypermetabolism of cerebellum and corticospinal tracts. The relative hypermetabolism in corticospinal tracts was more evident in the group with low UMN signs. Motor cortex metabolism reflects UMN burden. Corticospinal tracts' metabolic changes could provide information about UMN involvement even in patients with predominant LMN phenotype, suggesting a possible role of brain 2-[18F]FDG-PET as an UMN biomarker in ALS patients.

ID: 41256495
Title: Skin TDP-43 pathology as a candidate biomarker for predicting amyotrophic lateral sclerosis decades prior to motor symptom onset.
Abstract: The recognition that disease-associated proteinopathies can manifest in peripheral organs outside the central nervous system preceding the onset of neurological symptoms, has transformed our understanding of Parkinson's disease, in wide terms of pathogenesis, detection and diagnosis. For amyotrophic lateral sclerosis, non-motor symptoms, and non-central nervous system pathologies are gaining increased recognition but remain incompletely understood. Here, using a TDP-43 RNA aptamer and a Stathmin-2 cryptic exon transcript BaseScope™ ISH probe, we identify widespread peripheral organ TDP-43 pathology prior to motor symptom onset in a discovery cohort of ante-mortem tissues from people who went on to develop ALS. Peripheral organs exhibiting both TDP-43 toxic gain- and loss-of function include muscle, lymph node, gallbladder, colon and with notably high incidence, skin. Given the accessibility of skin as a readily biopsiable tissue, representing a promising substrate for the detection of disease-associated proteinopathies and the development of minimally invasive biomarkers, we established an extended cohort of ante-mortem skin samples for TDP-43 pathology validation and further investigation. In skin biopsies taken during life from 17 individuals who went on to develop ALS we identify TDP-43 pathology from all 17 individuals in a wide distribution of anatomical sites, up to 26.5 years before ALS diagnosis - a presymptomatic period comparable to that observed for skin α-synucleinopathy in Parkinson's disease. TDP-43 pathology was most abundant in skin biopsies from the back and shoulder, with sweat and sebaceous glands showing the highest involvement. TDP-43 pathology was also associated with structural changes. As skin α-synucleinopathy has been established as a biomarker for both the detection of Parkinson's disease and the differentiation of Parkinson's disease from multiple system atrophy, we propose that skin TDP-43 likewise holds diagnostic and discrimination potential for diseases characterised by TDP-43 proteinopathy.

ID: 41260310
Title: From molecular convergence to clinical divergence: Comparative pathogenic mechanisms and therapeutic trajectories in C9orf72-ALS/FTD and myotonic dystrophy.
Abstract: Short tandem repeat expansions in C9orf72, DMPK, and CNBP genes cause amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) and myotonic dystrophy types 1 and 2 (DM1/DM2), respectively. Despite distinct clinical phenotypes, these disorders share convergent molecular mechanisms with tissue-specific vulnerability, offering a framework to inform precision therapeutic strategies. Shared pathogenic features include nuclear RNA foci sequestering RNA-binding proteins that disrupt splicing, and repeat-associated non-AUG translation generating toxic dipeptide repeat proteins. In C9orf72, GGGGCC repeats form RNA-driven condensates, including protein-free condensates, via G-quadruplex formation. Evidence also implicates autophagy-lysosome and mitochondrial dysfunction, suggesting a potential "two-hit" loss/gain-of-function model. Clinically, C9orf72 expansions primarily affect motor neurons and frontotemporal circuits, with ALS progression typically occurring over 2-5 years. Conversely, myotonic dystrophy manifests as a muscle-predominant multisystem disorder progressing over decades. Genomic instability contributes to disease variability, with anticipation and parent-of-origin effects strongest in DM1, not confirmed in DM2 and controversial in C9orf72. Sequence interruptions modulate repeat stability and phenotype, influencing diagnostic interpretation. Therapeutic development has yielded contrasting outcomes. Antisense oligonucleotides targeting C9orf72 achieved target engagement and reduced dipeptide repeat proteins but failed clinically, potentially due to sense-strand selectivity and persistence of TDP-43 pathology. In contrast, RNA-targeting conjugates for DM1 (delpacibart etedesiran and DYNE-101) received FDA Breakthrough Therapy designation. Therapeutic success depends on tissue accessibility and addressing both shared and circuit-specific pathogenic cascades. While nuclear RNA targets appear druggable in myotonic dystrophy, the bidirectional transcription and compartmentalized pathology of C9orf72 ALS/FTD may require multi-targeted approaches for precision medicine.

ID: 41276696
Title: Label-free nonlinear microscopy probes cellular metabolism and myelin dynamics in live tissue.
Abstract: Metabolic coupling between neurons and glial cells plays a critical role in brain activity and myelin plasticity. Understanding its role in physiological and pathological contexts requires advanced methods to map metabolism and myelin in live tissue with high spatiotemporal resolution. Here, we present a label-free, multimodal, nonlinear optical microscopy platform integrated with an advanced image processing framework that simultaneously maps cellular metabolism and myelin distribution in organotypic cerebellar cultures. We combine third-harmonic generation microscopy for high-resolution myelin imaging with single axon precision with two-photon fluorescence lifetime microscopy of NAD(P)H metabolic biomarker to assess redox states with single-cell resolution. We introduce automated image analysis methods for cell segmentation and myelinated axon detection, enabling quantitative metabolic and myelin assessment in intact tissue during experimental myelination, demyelination and remyelination. Using this framework, we map the 3D myelin distribution in cerebellar folia and identify distinct metabolic signatures in neurons, oligodendrocytes, and microglia. Furthermore, we measure a metabolic shift in microglia along with myelin distribution changes during experimental demyelination. In conclusion, we establish label-free optical imaging as a powerful tool for the non-invasive characterization of neuro-glial metabolic coupling and myelin organization in living brain tissue, opening new perspectives for research in neuroinflammation and neurodegeneration.

ID: 41278665
Title: Glial cell-intrinsic and non-cell autonomous toxicity in a Drosophila C9orf72 neurodegeneration model.
Abstract: The most common genetic cause of both familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is an expanded G4C2 repeat in the first intron of the gene C9orf72. The C9orf72 repeat expansion is bidirectionally transcribed into sense and anti-sense RNA foci, and also produces dipeptide repeats (DPRs) via a non-canonical translation mechanism known as repeat-associated (RAN) translation. Each of these components of the G4C2 repeat expansion cause neurodegenerative effects in animal models when expressed in neurons, but impacts from glial expression are more poorly understood. Here, we use glial cell type-specific expression of individual DPRs, of RNA repeat-only, or of the G4C2 repeat that is capable of producing both DPRs and RNA repeats to systematically investigate both the glial cell-intrinsic and non-cell autonomous toxicity of each of these components. Our results show that as with neurons, the GR and G4C2 transgenes, produce the highest degree of cell-intrinsic toxicity when expressed in glia. Both of these transgenes are capable of producing the GR DPR, which is also typically found to be the most toxic factor in neurons. We demonstrate that both the GR and G4C2 transgenes cause activation of mdg4, an endogenous retrovirus (ERV). Such ERV expression is a hallmark of TDP-43 dysfunction that is commonly observed in C9orf72 patients and contributes to both cell intrinsic and non-cell autonomous toxicity. We find that only the G4C2 transgene produces measurable non-cell autonomous effects that result in loss of nearby neurons. But manipulations of apoptosis reveal non-cell autonomous or systemic effects from either GR or G4C2 expressing glia. Blocking apoptotic cell death of either GR or G4C2 expressing glia via the p35 caspase inhibitor further exacerbates effects on lifespan and ablating such glia via expression of the proapoptotic reaper gene partially ameliorates these effects.

ID: 41280089
Title: TDP-43 dysfunction leads to impaired proteostasis and predisposes mice to worse neurological outcomes after brain injury.
Abstract: Pathological TAR DNA-binding protein 43 (TDP-43) dysfunction is associated with multiple neurodegenerative disorders. However, the mechanistic link between TDP-43 dysfunction and neurodegeneration is poorly understood and likely involves a combination of genetic and environmental risk factors. A major risk factor for neurodegenerative disease is exposure to traumatic brain injury (TBI). Here, we investigated the synergistic interplay between TDP-43 dysfunction and TBI in a murine model of amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). A model of TDP-43 dysfunction caused by a knock-in Q331K mutation in Tardbp was combined with a mild model of TBI. Control conditions included both WT mice and mice with sham surgery. Animals were evaluated for behavioral deficits at timepoints pre- and post-surgery. Additionally, post-mortem brain tissues were examined using RNA sequencing and mass spectrometry-based quantitative proteomics together with histological and biochemical analyses. Expression of dysfunctional TDP-43 in vivo caused deficits in multiple branches of the proteostasis network, including protein folding, protein synthesis, and protein turnover. Examples include mis-expression of chaperones and genes within the ubiquitin-proteosome pathway in mutant TDP-43 versus WT mice. Further, mutant TDP-43 expression correlated with reduced thermostability of proteins associated with the ribosome and the chaperonin containing TCP-1 complex. In response to TBI, mutant TDP-43 mice exhibited significantly worse neurological outcomes relative to WT animals. Heightened neurological deficits in mutant TDP-43 mice following TBI coincided with a robust upregulation of proteostasis- and stress-related genes at the transcript level. However, this upregulation was not detected at the protein level. Our data demonstrate that expression of dysfunctional TDP-43 leads to deficits within the proteostasis network in vivo at baseline. Despite an upregulation of proteostasis-related genes at the transcript level in mutant TDP-43 mice after TBI, mutant TDP-43 mice exhibit an impaired response to, and recovery from, brain trauma relative to their WT counterparts. Restoring proteostasis is expected to protect against the detrimental effects of TDP-43 dysfunction, especially under stress conditions that promote neurodegenerative disease.

ID: 41366786
Title: Quantifying multimodal longitudinal brain changes in presymptomatic C9orf72 disease.
Abstract: The presymptomatic phase of frontotemporal dementia and amyotrophic lateral sclerosis associated with C9orf72 repeat expansion features widespread structural brain changes. We aimed at fulfilling the unmet need of quantitative magnetic resonance imaging (MRI)-derived measures suitable for disease tracking. We compared the profile of longitudinal gray (GM) and white matter (WM) changes in 66 presymptomatic carriers and 52 controls over 3-year follow-up and appraised their annualized rate of change (ARC). Both putamen (p < 0.01) and left insula (p = 0.005) volumes declined the most in carriers over 40, with an ARC up to four-fold higher than in controls. Increases in mean diffusivity occurred first in the left uncinate fasciculus, followed by thalamo-cortical bundles (p < 0.05), associated with higher neurofilament levels. Our study highlighted the GM and WM structures showing the greatest longitudinal decline during the preclinical stage, whose ARC may serve as an MRI-derived biomarker for longitudinal surveillance and therapeutic outcome. NCT02590276 and NCT05358431. We studied longitudinal multimodal MRI changes in presymptomatic C9orf72 disease. Carriers displayed faster atrophy in putamen, insula and cerebellar regions. Mean diffusivity increased mainly in uncinate and thalamo-cortical tracts. These differences were even more significant in older (> 40) participants. We proposed targeted annualized rate of change as a quantitative biomarker.

ID: 41399249
Title: Detection of TDP-43 seeds in CSF of presymptomatic and symptomatic genetic FTD/ALS.
Abstract: Seed amplification assays (SAAs) have shown promising results in detecting misfolded transactive response (TAR) DNA-binding protein 43 (TDP-43) in cerebrospinal fluid (CSF) of genetic frontotemporal dementia (FTD). To date, the use of SAA has yet to be evaluated in presymptomatic individuals. Thirty patients carrying GRN or C9orf72 mutations, 2 microtubule-associated protein tau (MAPT) carriers, 14 presymptomatic subjects, and 27 controls underwent CSF collection. We used SAA for detecting misfolded TDP-43 (TDP-43_SAA) and single molecule array (SIMOA) technology for neurofilament light chain (NfL) dosage. TDP-43 seeding activity was detected in 67% of TDP-43-linked symptomatic patients, with a specificity of 93%. Almost half of presymptomatic subjects tested positive, mostly GRN carriers. Interestingly, among TDP-43_SAA positive presymptomatic individuals, two GRN carriers underwent phenoconversion. TDP-43_SAA can also detect misfolded TDP-43 in the CSF of presymptomatic individuals. A possible link exists between positive TDP-43_SAA and conversion to the symptomatic phase. Seed amplification assay of transactive response (TAR) DNA-binding protein 43 (TDP-43_SAA) can detect misfolded TDP-43 in the cerebrospinal fluid (CSF) of patients with genetic frontotemporal dementia (FTD), linked to GRN and C9orf72 mutations. TDP-43_SAA can detect misfolded TDP-43 also in the CSF of presymptomatic individuals. In both groups, most TDP-43_SAA positive cases were carriers of GRN mutation. Two GRN carriers that resulted TDP-43_SAA positive converted to the symptomatic phase of the disease.

ID: 41497595
Title: Lysosomal escape and TMEM106B fibrillar core determine TDP-43 seeding outcomes.
Abstract: Frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP) shows striking clinical and neuropathological heterogeneity, yet a systematic analysis of subtype-specific features and inter-patient variability was missing. We treated human neurons and neuron-like cells with 30 postmortem brain samples and quantified neoaggregate formation, loss of function and changes in the TDP-43 interactome to define determinants of seeding outcomes. Potent FTLD-TDP-A seeds drove a progressive collapse of physiological TDP-43 interactions accompanied by functional loss. Beyond the burden of pathological TDP-43, we identified the fibrillar core of the lysosomal protein TMEM106B as a critical pro-seeding factor. Transient lysosomal injury markedly enhanced neoaggregation and loss of function, likely by promoting fibril interactions with native TDP-43. Our work establishes a mechanistic link between TMEM106B and TDP-43 aggregation, identifies lysosomal escape as a key driver of pathology and introduces the strongest model yet for seeded TDP-43 aggregation and loss of function, to enable discovery of disease modifiers.

ID: 41547996
Title: γ-Radiation induces region-specific subcellular alterations of amyotrophic lateral sclerosis and frontotemporal dementia markers in swine brain.
Abstract: Low-dose radiation (LDR) effects on the brain have been poorly investigated. Studies have also questioned whether radiation increases ALS risk. We assessed the expression levels of a series of proteins associated with ALS and ALS-FTD in the brains of swine exposed to low-dose radiation to explore this notion. Male Gottingen minipigs were exposed to a single total-body γ-radiation (1.79 Gy). After 28 days, brains from 9 RAD to 6 SH animals were collected. Using neuroanatomically based dissection and Western Blotting, we compared levels of ALS/ALS-FTD markers (SOD1, FUS/TLS, C9orf72, STMN2, ubiquitin, TDP43 (N and C terminal), and pTDP43) in RAD vs. SH animals in frontal cortex (FCtx), striatum (Str), hippocampus (Hip), thalamus/hypothalamus (Thal/Hyp), and cerebellum (Cere). Cytosolic FUS/TLS decreased in the Thal/Hyp and remained unchanged in all other regions; nuclear levels increased in the FCtx and decreased in the Hip of RAD vs. SH. Cytosolic C9orf72 remained unchanged across all brain regions; nuclear levels decreased in the Hip of RAD vs. SH. Cytosolic STMN2 remained unchanged in all brain regions and decreased in the nuclear fraction of the Hip of RAD vs. SH. Cytosolic and nuclear ubiquitin remained unchanged across brain regions, except for an increase in the FCtx. TDP-43 (N and C terminal) levels remained unchanged in cytosolic and nuclear fractions across all brain regions; finally, cytosolic pTDP43 (S403/404) increased in the FCtx, Str and Thal/Hyp of RAD vs. SH. LDR-induced ALS/ALS-FTD-marker changes differ across brain regions and subcellular compartments. These changes are not necessarily associated with increased activation or potentiation of the main molecular processes associated with ALS pathogenesis; surprisingly, they may produce beneficial effects.

ID: 41612503
Title: Diagnostic potential of cryptic exon-derived peptides in serum extracellular vesicles for sporadic amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive degeneration and loss of upper and lower motor neurons, with approximately 90% of cases being sporadic (sporadic ALS, SALS). A reliable diagnostic biomarker remains an unmet clinical need in SALS, with misdiagnosis and diagnostic delay hindering early management. The mislocalization of the RNA-binding protein TDP-43 (encoded by TARDBP), a pathological hallmark of SALS, could lead to aberrant splicing that produces transcripts with cryptic exons and, consequently, cryptic peptides. This study proposes cryptic peptides in serum extracellular vesicles as a novel candidate diagnostic biomarker of SALS. We included 10 healthy controls and 20 patients with SALS and quantified cryptic peptides predicted from cryptic exon sequences using mass spectrometry-based proteomics. Cryptic peptides from four proteins (RANBP1, IGLON5, ACTN1, ALPK2) were detected in participants, with the IGLON5 cryptic peptide detected significantly more frequently in SALS than in HC (adjusted P = 0.044). The number of detected cryptic peptides classified SALS and healthy controls with acceptable performance (area under the curve = 0.82). In conclusion, cryptic peptides could have diagnostic performance for SALS, warranting further validation.

ID: 41776751
Title: Proteomic profile of CSF obtained at the time of diagnosis determines amyotrophic lateral sclerosis progression and survival: CXCL7 levels in disease prognosis and survival.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease primarily affecting motor neurons. Neurofilament light chain (NfL) is the most established prognostic biomarker; however, its diagnostic resolution is limited, particularly within intermediate concentration ranges, and it does not capture the molecular heterogeneity of ALS. This study aimed to identify complementary cerebrospinal fluid (CSF) biomarkers and pathway-specific signatures through a non-targeted multiomic approach. We performed SWATH-MS-based proteomics and LC-MS/MS lipidomics on CSF from ALS patients stratified by survival (ALS-SS and ALS-LS) and healthy controls. Weighted protein co-expression network analysis (WPCNA) was applied to identify biologically coherent protein modules associated with disease phenotype and progression. Top biomarker candidates were further evaluated using immunoassays in an independent cohort. Post-mortem ALS spinal cord tissues were analyzed to explore the pathophysiological relevance of identified proteins. CSF proteomic profiles robustly distinguished ALS patients from controls and stratified patient subgroups by survival, revealing a molecular signature characterized by inflammation, downregulation of detoxification mechanisms, and synaptic dysregulation in aggressive disease forms. In contrast, lipidomic profiles showed limited discriminatory power. WPCNA identified modular proteomic signatures capturing ALS heterogeneity, and machine learning models based on these profiles yielded optimal biomarker panels for diagnosis and prognosis. CXCL7 emerged as a promising complementary biomarker, and shed light in disease physiopathology. Immunoassay validation supported the diagnostic and prognostic potential of CXCL7 and its association with survival time. Histopathological analysis further confirmed CXCL7 localization in anterior horn motor neurons, despite no detectable changes in whole spinal cord lysates at late disease stages. Comprehensive CSF proteomic profiling, combined with network-based analysis, enhances our understanding of ALS molecular heterogeneity and provides a framework for precision biomarker discovery. CXCL7 complements NfL as a diagnostic and prognostic biomarker, supporting improved patient stratification and advancing the development of personalized therapeutic strategies in ALS.

ID: 41810938
Title: PAICS mediates DNA damage and cerebellar neuronal loss in C9orf72 amyotrophic lateral sclerosis.
Abstract: A hexanucleotide (GGGGCC) repeat expansion in C9orf72 gene represents the most frequent genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), resulting in reduced C9orf72 mRNA and protein expression. C9orf72 is highly expressed in the cerebellum and growing evidence implicates C9orf72-associated cerebellar pathology across neurodegenerative disorders including ALS/FTD, yet the pathogenic mechanisms remain unresolved. Here, we demonstrate in vivo C9orf72 loss of function leads to cerebellar atrophy, loss of GABAergic interneurons, and depletion of Purkinje and Granule cells. Additionally, we demonstrate that these cerebellar anomalies precede motor defects. Single-cell transcriptomics of the C9orf72-zebrafish brain revealed the downregulation of a purine biosynthetic gene paics in Purkinje cells. Furthermore, we demonstrate the reduced expression of PAICS in the human post-mortem cerebellar sections and iPSC-derived motor neurons from C9orf72 and sporadic ALS patients. Knockout of paics in zebrafish recapitulates cerebellar neuronal loss, neuromuscular junction disruption, motor impairment and widespread DNA damage and repair (DDR) defects including suppression of key DNA repair pathways. Restoring paics expression in C9orf72 zebrafish resolves DNA damage and preserves Purkinje cells and Granule cells, revealing PAICS as a critical mediator of cerebellar degeneration and a promising therapeutic avenue for C9orf72-associated ALS and FTD.

ID: 41813079
Title: OCT-based myopic index: a biological predictor for the progression of high myopia.
Abstract: The growth of axial length (AL) can lead to high myopia and ocular deformation, especially causing microstructural changes in the fundus, which cannot be fully quantified by AL alone. We propose an optical coherence tomography (OCT)-based modified AL (Myopic Index) to represent the extent of fundus deformation caused by AL elongation and to explore its clinical significance in myopic progression prediction. A deep learning model was trained using 27 539 cases of OCT images and referred ocular biometric data to evaluate the Myopic Index. By comparing the Myopia Index with the Measured AL, the difference of two AL indices (DAL) was calculated. We further prospectively employed 2866 cases of OCT images, which were categorised into short AL (Measured AL<22 mm), normal AL (22 mm≤Measured AL<26 mm) and long AL (≥26 mm), to evaluate the model ability of myopic progression prediction. The attention regions of images were also analysed. The Myopia Index was closely correlated with Measured AL (all p<0.001, R²=0.804 in all eyes). Specifically, the Myopia Index was closer to the Measured AL in eyes with long ALs, whereas in eyes with short and normal axial lengths, the Myopia Index clustered around 23-24 mm. The visualisation model demonstrated that for eyes with short and normal ALs, attention regions were primarily concentrated on the retina; conversely, for eyes with long ALs, the choroidal layer and the retinal pigment epithelium layer received more attention. Moreover, DAL was significantly correlated with AL increment (p=0.038). The Myopia Index reflects the real status of fundus microstructures through fundus microstructures, with a particular focus on the choroid. The Myopia Index demonstrates good predictive capabilities for high myopia progression.

ID: 41890591
Title: Axonal transport impairment as an upstream mechanism in amyotrophic lateral sclerosis pathogenesis.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive loss of upper and lower motor neurons. Despite marked genetic and pathological heterogeneity, a unifying pathogenic framework remains lacking. We propose that axonal transport impairment represents an early and convergent but genotype-modulated upstream vulnerability in ALS, contributing to distal synaptic failure, bioenergetic stress, protein aggregation, neuroinflammation, and neuronal death. Across many ALS models, including SOD1, TARDBP (TDP-43), FUS, and C9orf72, transport deficits are frequently detectable in presymptomatic stages, often preceding overt motor neuron loss or clinical manifestation, although temporal ordering varies by molecular subtype. Human data from induced pluripotent stem cell-derived motor neurons and neuroimaging in mutation carriers further support early transport dysfunction in both familial and sporadic ALS. We synthesize genetic, cellular, and systems-level evidence demonstrating that diverse ALS-associated mutations converge on intracellular trafficking machinery through distinct but interacting mechanisms, disrupting long-range cargo delivery and clearance in motor neurons. This framework provides a mechanistic basis for selective motor neuron vulnerability, the dying-back pattern of neuromuscular junction degeneration, and the emergence of downstream pathological hallmarks including mitochondrial dysfunction, excitotoxicity, aggregation, and inflammation. This model generates testable predictions regarding presymptomatic transport biomarkers and the timing of therapeutic intervention. We discuss implications for biomarker development and therapeutic strategy, proposing restoration of axonal transport as a central component of rational multimodal disease modification in ALS.

ID: 41897327
Title: Selective Silencing of TDP-43 P. G376D Mutation Reverses Key Amyotrophic Lateral Sclerosis-Related Cellular Deficits.
Abstract: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease for which there is currently no cure. Dominant mutations in the TARDBP gene are causative of ALS. In particular, the p. G376D substitution in TDP-43 causes familial ALS and it is associated with TDP-43 mislocalization in the cytosol, increased presence of cytoplasmic aggregates, and lysosomal and mitochondrial dysfunction. We previously designed a small interfering RNA (siRNA) that specifically targets and silences the mutant allele and we demonstrated that, in patient-derived fibroblasts, it can reduce TDP-43 aggregation, decrease oxidative stress, and improve cell viability. Here, we investigated the ability of this siRNA to revert some ALS-associated pathological phenotypes in motor neurons derived from induced pluripotent stem cells (iPSCs), as motor neurons are the primary cells affected in ALS. siRNA treatment reduced TDP-43 mislocalization, enhanced lysosomal function and cell viability, and decreased oxidative stress. These findings indicate that this allele-specific siRNA effectively reverses key ALS-related cellular deficits in motor neurons, representing a promising candidate for targeted therapy in patients carrying the TDP-43 G376D mutation.

ID: 41900026
Title: Chemical and Molecular Strategies in Restoring Autophagic Flux in TDP-43 Proteinopathy.
Abstract: The cytoplasmic accumulation of TDP-43 aggregates remains a persistent pathological hallmark of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and limbic-predominant age-related TDP-43 encephalopathy (LATE). The cell's natural clearance mechanisms, the Ubiquitin-Proteasome System (UPS) and the autophagy-lysosome pathway (ALP), are hypothesized to fail, at least in part, due to the sequestration of key components of these pathways by pathological TDP-43 species, thereby impairing autophagosome-lysosome fusion and lysosomal competence. Classical autophagic activators (e.g., rapamycin) can initiate upstream steps in the pathway but cannot address downstream flux bottlenecks, limiting their ability to restore effective TDP-43 clearance. This review revisits classical strategies and discusses newer approaches to modulate TDP-43 clearance, including transcription factor EB (TFEB) activators, proteolysis-targeting chimeras (PROTACs), and antisense oligonucleotides (ASOs). We propose that adopting multi-targeting strategies and developing better biomarkers are vital for clinical success.

ID: 41910849
Title: Enhancing Parkinson's Disease Staging: An Integrative Deep Learning Framework for Multimodal Feature Selection.
Abstract: Parkinson's disease (PD) affects 10 million globally, with accurate staging essential for personalized treatment planning. Current UPDRS assessments achieve < 93% accuracy due to subjective clinical judgment and unimodal data limitations, failing to capture complex genetic-neuroimaging-clinical interactions driving disease heterogeneity. This study introduces MAFNet, a novel deep learning framework pioneering Iterative Adaptive Vold-Kalman Filter (IAVKF) temporal denoising, Accelerated Binary Particle Swarm Optimization (ABPSO) swarm feature selection, Multilayer Perceptron-Lagrangian Support Vector Machine (MLP-LSVM) classification, and Graph-Attention Based Multimodal Fusion Network (GAMF). Applied to PPMI cohort (200 patients) with genetic SNPs (50), neuroimaging voxels (1,024), and UPDRS-III scores, the end-to-end pipeline delivers 97.6% accuracy, 98.2% precision, 96.8% recall, and 97.3% F1-score-outperforming CNN (92.4%), Autoencoder (90.8%), InceptoFormer (96.6%), and HCT (97.0%). IAVKF boosts SNR + 15.2dB (+ 2.9% accuracy vs. PCA/t-SNE); ABPSO reduces 1,276→340 features (73% reduction); regularization cuts overfitting gap to 0.9% (vs. 4.2% baseline). SHAP interpretability validates clinical plausibility (top predictors: LRRK2 SNPs, UPDRS-III tremor, hippocampal volume). Five-fold CV confirms stability with the Indian cohort external validation. Real-time inference (0.2s/patient, RTX 3090) enables clinical deployment. Future scope includes longitudinal temporal modelling, modality-agnostic fusion, edge deployment, federated learning, and extension to Alzheimer's/ALS. MAFNet transforms PD staging from subjective assessments to objective precision medicine, enabling biomarker discovery, progression forecasting, and personalized therapies across diverse global populations.

ID: 41925964
Title: The Gut Microbiome in Amyotrophic Lateral Sclerosis: Emerging Mechanisms and Therapeutic Potential.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder marked by progressive loss of motor neurons and a median survival of 2 to 3 years after symptom onset. Despite advances in genetics, particularly the identification of mutations in C9ORF72, SOD1, and TDP 43, substantial variability in disease onset and progression remains unexplained. Mounting evidence points to the gut microbiome as a potential modifier of ALS biology. Microbial communities within the intestine influence systemic and central immune responses, energy metabolism, and the bioavailability of nutrients and therapeutic agents. Animal studies reveal that dysbiosis contributes to intestinal barrier dysfunction, immune activation, and altered metabolite production, while supplementation with beneficial metabolites such as butyrate or nicotinamide can delay disease progression and extend survival. Human studies, though inconsistent in their findings, consistently identify microbial imbalances and loss of diversity in subsets of patients. The gut-brain axis provides a plausible framework for these effects, as microbial products can signal through endocrine, neural, and immune pathways to influence central nervous system function. Beyond motor decline, microbiota alterations may also contribute to non-motor symptoms such as depression, anxiety, and gastrointestinal dysfunction, further shaping quality of life. While methodological variability complicates interpretation, integration of microbiome research with host genomics and metabolomics offers a path toward precision medicine. Targeting microbial composition and function may ultimately represent a novel therapeutic approach capable of modifying both disease biology and patient outcomes in ALS.

ID: 41926608
Title: Relationship between promyelocytic leukemia protein nuclear bodies and TAR DNA-binding protein-43 aggregation in spinal anterior horn cells in sporadic amyotrophic lateral sclerosis.
Abstract: Promyelocytic leukemia protein nuclear bodies (PML-NBs) and stress granules serve as deposition sites for stress-induced, aggregation-prone proteins. We previously reported that TAR DNA-binding protein 43 (TDP-43) colocalizes with stress granules during early aggregation in sporadic amyotrophic lateral sclerosis (ALS), and recent studies have noted PML-NB loss in familial ALS. To explore the role of PML-NBs in TDP-43 inclusion maturation, we analyzed spinal cord specimens from 12 patients with sporadic ALS and 5 controls using immunostaining for PML and TDP-43. PML-NB counts in anterior horn cells (AHCs) were significantly lower in patients with ALS than in controls (P < 0.05), especially in AHCs with TDP-43 inclusions (P < 0.01). Average numbers of PML-NB decreased progressively with inclusion type (3.1 in diffuse punctate cytoplasmic staining, 2.3 in round inclusions, and 0.8 in skein-like inclusions); all of these were significantly lower than those in inclusion-free AHCs (controls: 4.6; ALS: 5.5; P < 0.01). AHCs in ALS without inclusions showed higher PML-NB counts than in controls (P < 0.05), suggesting an early protective response. In contrast, reduced PML-NBs in mature inclusions may reflect diminished cellular defense. These findings implicate PML-NBs in the pathogenesis of sporadic ALS.

ID: 41928938
Title: Multimodal analysis of cell-free DNA identifies epigenetic biomarkers for amyotrophic lateral sclerosis diagnosis and progression.
Abstract: The role of the epigenome in age-related neurodegenerative disorders remains understudied. Here, we analyzed circulating cell-free DNA (cfDNA) from blood to detect methylation changes as a liquid-biopsy for Amyotrophic Lateral Sclerosis (ALS). Our study included 20 patients with sporadic ALS, 10 patients with C9orf72-associated ALS, 10 asymptomatic carriers of the C9orf72 repeat expansion mutation, and 21 non-disease controls. Following targeted enzymatic methyl-sequencing (EM-seq) of ~4 million CpG sites, we detected numerous differentially methylated genes, including several implicated in ALS disease risk and pathogenesis. By integrating multiple epigenetic features, we delineated a distinct epigenetic signature, which achieved an average area under the curve (AUC) of 0.91 ± 0.10 upon receiver operator characteristic (ROC) analysis, which enabled detection of ~70% of ALS patients with close to 100% specificity. Furthermore, we also identified a set of genes whose methylation status significantly correlated with clinical disease progression and cerebrospinal fluid (CSF) neurofilament levels. Our results reveal the potential of cfDNA-based biomarkers to accurately diagnose ALS and potentially predict disease progression.

ID: 41929296
Title: Longitudinal Analysis of Superoxide Dismutase 1 Seeding Activity in Amyotrophic Lateral Sclerosis Cerebrospinal Fluid.
Abstract: 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.

ID: 41996987
Title: Decoding RNA splicing pathology: Alternative splicing in amyotrophic lateral sclerosis and its therapeutic potential.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder marked by progressive motor neuron loss, leading to muscle weakness, paralysis, and respiratory failure. Dysregulation of RNA metabolism and splicing has emerged as a central mechanism in ALS pathogenesis. TARDBP (TAR DNA-binding protein), FET family proteins (FUS, EWSR1, TAF15), SOD1 (Superoxide Dismutase 1), and C9orf72 (Chromosome 9 Open Reading Frame 72) are key genes associated with ALS that regulate RNA processing, alternative splicing, and nuclear-cytoplasmic transport. Mutations or mislocalization of these proteins result in nuclear loss-of-function and cytoplasmic gain-of-function toxicity, promoting protein aggregation, sequestering spliceosomal components, and impairing spliceosome assembly. This leads to the aberrant inclusion of cryptic exons in essential neuronal genes, such as STMN2 (Stathmin 2) and UNC13A (Unc-13 Homolog A), resulting in the production of truncated proteins, defective axonal maintenance, and impaired synaptic function. TDP-43 pathology, a hallmark of ALS, disrupts splicing and RNA transport, while C9orf72 repeat expansions and FET protein mutations exacerbate cytoplasmic aggregation and stress granule dynamics. Mutant SOD1 contributes via mitochondrial dysfunction, endoplasmic reticulum stress, and disrupted axonal transport. Therapeutic strategies targeting these mechanisms are advancing rapidly. Gene replacement therapy, which restores STMN2 expression, and antisense oligonucleotides (ASOs) targeting mutant transcripts show promise in preclinical and early clinical studies. Complementary approaches, including the inhibition of stress kinases and the activation of autophagy, reduce cytoplasmic protein aggregation and support neuronal homeostasis. This review provides a comprehensive overview of RNA splicing regulation, spliceosomal dysfunction, and cryptic exon incorporation in ALS. Understanding the interplay among splicing defects, RNA-binding protein pathology, and neuronal degeneration is critical for developing next-generation multimodal therapies to restore RNA processing, reduce toxic protein accumulation, and promote motor neuron survival.

ID: 42102258
Title: King's stages of amyotrophic lateral sclerosis: an 18F-FDG-PET study of brain connectivity.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting upper and lower motor neurons. TDP-43 proteinopathy is the neuropathological signature of the disease, and 18F-FDG-PET serves as a marker of neurodegeneration in vivo. The aim of the present cross-sectional study was to disentangle 18F-FDG-PET correlates of disease severity assessed through the King's staging system, by exploring connectivity changes across motor stages. ALS patients classified as King's stage 1, 2 and 3, who underwent brain 18F-FDG-PET at diagnosis from 2008 to 2022 at the ALS Centre of Turin, were included. A multiple regression analysis to evaluate the relationship between brain metabolism and King's stage was performed. The clusters showing significant results were used as seed regions in an inter-regional correlation analysis (IRCA), performed for each stage. Out of a total of 832 ALS patients, 337 were classified as King's stage 1, 274 as stage 2, and 221 as stage 3. The three groups significantly differed in age at PET, disease duration and total ALSFRS-R score at the time of PET, C9ORF72 status, and the distribution of cognitive categories. We found a decreasing metabolic gradient from King's stage 1 to King's stage 3 in a cluster encompassing motor and cognitive areas. As King's stage increases, we found a decrease of connectivity within the sensorimotor and cognitive areas. The IRCA also showed the connectivity of motor and cognitive regions with temporal and cerebellar regions. The connectivity with temporal regions found in King's stage 1 decreases in King's stage 2 and finally disappears in King's stage 3. The connectivity with the cerebellum occurs in King's stage 2 and decreases in King's stage 3. The changes of connectivity of motor and cognitive areas with temporal and cerebellar regions among different King's stages might reflect the spread of TDP-43 proteinopathy or a compensatory mechanism, respectively. The present study suggests that 18F-FDG-PET imaging of the brain may be integrated with King's staging system to assess the extent of the pathogenic process in the context of clinical trials.

ID: 42103041
Title: Multimodal strategies for diagnosis, stratification, and therapeutic monitoring in ALS.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder of motor neurons (MN) that is currently diagnosed through a prolonged process of exclusion, often delaying intervention. This review provides an overview of fluid, imaging, electrophysiological, and genetic biomarkers, explicitly linking each modality to early detection, patient stratification, disease monitoring, therapeutic development, and clinical trial design. Fluid biomarkers (i.e., neurofilament light chain, phosphorylated neurofilament heavy chain, inflammatory cytokines, microRNAs, and proteins in blood or cerebrospinal fluid) reflect neuronal injury and/or disease activity, enabling early identification of pres-ymptomatic individuals and longitudinal tracking of neurodegeneration. Imaging biomarkers, such as structural and diffusion MRI of the motor cortex, corticospinal tracts, and spinal cord, as well as PET imaging neuroinflammation or metabolism, provide objective measures of MN degeneration and extra-motor involvement. Electrophysiological biomarkers, including high-density electromyography, motor unit number, transcranial magnetic stimulation, and electrical impedance myography, quantitatively assess upper and lower MN loss and functional reserve. Genetic biomarkers, encompassing variants in genes such as C9orf72, SOD1, FUS, and TARDBP, enable presymptomatic screening and molecular stratification. In this context, transposable elements have emerged as an additional layer linking genomic variation and RNA dysregulation. We highlight the importance of multimodal and stage-specific biomarker integration to improve diagnostic accuracy and illuminate distinct disease phases. This approach supports stratification by progression rate or molecular subtype, enrichment of clinical trial cohorts, and the development of surrogate endpoints. We conclude by discussing current challenges, including disease heterogeneity and assay standardization, and outline future directions toward biomarker-driven precision medicine in ALS.

ID: 42127333
Title: Serum Glial Fibrillary Acidic Protein and Retinal Neuronal Loss as Additive Prognostic Markers of Disability in Multiple Sclerosis.
Abstract: In people with multiple sclerosis (pwMS), optical coherence tomography (OCT) quantifies loss of neurons (macular ganglion cell-inner plexiform layer [mGCIPL]) and axons (peripapillary retinal nerve fiber layer [pRNFL]) in the retina. Serum glial fibrillary acidic protein (sGFAP) is a promising astrocytic biomarker to capture disease progression in pwMS. We aimed to investigate the relationship between OCT markers and sGFAP in pwMS and explore their additive value in predicting disability progression. PwMS and healthy controls underwent OCT at baseline (BL), excluding eyes with inter-eye asymmetry. Age, sex, and body mass index-adjusted Z scores of sGFAP were calculated. Cross-sectional and longitudinal associations between sGFAP and retinal layers were estimated using linear regression- and mixed-effects models (LMM). The additive effect of BL-OCT and BL-sGFAP on the trajectory of the Expanded Disability Status Scale (EDSS) was estimated using LMM, whereby pwMS were stratified into: group (1): low sGFAP Z score (<3rd quartile, <Q3) and thick mGCIPL (>Q1); group (2): high sGFAP Z score (≥Q3) and thick mGCIPL or low sGFAP Z Score and thin mGCIPL (≤Q1); and group (3): high sGFAP and thin mGCIPL. Two hundred and sixty-one pwMS (mean age: 48 years (y), female: 63%, on disease-modifying treatment: 80%, mean thickness of pRNFL: 94 μm and mGCIPL: 66 μm) and 52 controls (age: 52 years, female: 65%, pRNFL: 101 μm, mGCIPL: 72 μm) were included. At BL, pRNFL (β = -0.01, p = 0.042) and mGCIPL (β = -0.02, p = 0.013) were negatively associated with sGFAP Z scores in pwMS, but not in controls (p = 0.950, p = 0.386). BL-mGCIPL was also associated with sGFAP trajectories (β = -0.003, p = 0.044), over a median follow-up of 2.9 years. Compared with pwMS with good results in both markers (group 1), those with either high sGFAP or thin mGCIPL had a steeper EDSS increase (β = 0.030, p = 0.048), while pwMS with both high sGFAP and thin mGCIPL (group 3) showed the steepest trajectory of the EDSS (β = 0.101, p < 0.001). Our findings show a close relationship between astrocytic activation/injury and neurodegeneration in the CNS, measured at the retinal level. Moreover, they highlight an additive role of mGCIPL and sGFAP for identification of pwMS at higher risk of disability worsening.

ID: 42135512
Title: Integrated single-cell and spatial transcriptomic profiling in ALS uncovers peripheral-to-central immune infiltration and reprogramming.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder marked by progressive motor neuron (MN) degeneration in the brain and spinal cord. Although neuroinflammation is increasingly recognized as a hallmark of ALS, the precise molecular programs linking immune responses to MN pathology remain poorly defined. Using an integrated approach that combines single-cell and bulk RNA sequencing with spatial proteogenomics, we characterized both shared and distinct immune dynamics in peripheral blood and spinal cord tissues from patients with sporadic ALS and those carrying C9orf72 repeat expansions. Our analysis revealed broad immune remodeling in C9orf72 ALS, ALS subtype-specific and progression-associated differences in monocyte activation and antigen-experienced CD8 effector memory T cells with clonal features consistent with antigen-driven responses. Spatial mapping revealed complement activation and lipid-programmed myeloid states converging at sites of MN loss and TDP-43 pathology. Together, these findings connect peripheral and central immune alterations to ALS heterogeneity and highlight stratified immunomodulation as a potential therapeutic strategy.

ID: 42145633
Title: Functional Activity of TDP-43: A Direct Biomarker for ALS.
Abstract: TDP-43 dysfunction is a defining feature of amyotrophic lateral sclerosis (ALS), yet no biofluid biomarker directly measures its functional activity. We developed a serum-based homogeneous time-resolved FRET (hTR-FRET) assay that quantifies TDP-43 RNA-binding activity using synthetic UU rich RNA probes. We analyzed 1,080 serum samples from controls, sporadic ALS, and genetic subgroups (C9orf72, SOD1) across multiple biorepositories. Cross-sectionally, TDP-43 ligation activity was elevated in ALS (mean 390 a.u.) versus controls (304 a.u.), yielding AUC = 0.79. Genotype means were 392 a.u. (sporadic), 382 a.u. (C9orf72), and 323 a.u. (SOD1); with a 366 a.u threshold achieved 95% specificity against controls. Longitudinally, Target ALS showed a modest but significant inverse correlation between TDP-43 activity and ALSFRS-R, while other cohorts exhibited similar non-significant trends. Elevated signal likely reflects increased extracellular, probe-competent TDP-43 species. This assay provides direct functional measurement of disease-relevant TDP-43 biology, supporting applications in diagnostic discrimination, genotype stratification, and progression monitoring in prospective studies.

ID: 42158589
Title: CHI3L1 (YKL-40) and Chit-1 expressing glia in the white matter of ALS, FTLD and AD: correlations to pathology and disease duration.
Abstract: Chitotriosidase (Chit-1) and chitinase-3-like protein 1 (CHI3L1) protein levels are increased in the cerebrospinal fluid (CSF) of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) and Alzheimer's disease (AD). Few studies have examined the spatial expression of chitinase-expressing cells with respect to neuropathologic hallmarks of disease. RNA sequencing was used to examine Chit-1 and CHI3L1 gene expression in the spinal cord and motor cortex. Immunohistochemistry was used to characterise the distribution of Chit-1 and CHI3L1 expressing cells in ALS, C9-ALS, FTLD, AD and non-neurologic disease controls. Immunofluorescence confocal microscopy was used to correlate distribution of Chit-1 and CHI3L1 expressing cells to TDP-43 pathology. Chit-1 gene expression was increased in the spinal cord, and CHI3L1 expression was increased in both the spinal cord and motor cortex of patients with sALS and C9-ALS when compared with controls. Highest levels of Chit-1+ glia were in cortical regions that contain hallmark neuropathology for each neurodegenerative disease. CHI3L1+ glia were only significantly increased in sALS. Neither Chit-1+ nor CHI3L1+ glia was in close proximity to phosphorylated TDP-43 (pTDP) containing neurons in the motor cortex grey matter; however, there was a significant co-localisation of glial pTDP with Chit-1 and CHI3L1 in the motor cortex white matter. Chit-1 and CHI3L1 expressing cells were most abundant in the white matter of cortical regions affected by each neurodegenerative disease and the spinal cord. Chit-1 or CHI3L1 expressing cells in the white matter often contained pTDP. We also observed correlations between levels of Chit-1 or CHI3L1 expressing cells in the white matter to disease duration.

ID: 42163674
Title: Unraveling the Pathological Mechanisms and Biomarkers of Amyotrophic Lateral Sclerosis: A Comprehensive Review.
Abstract: Amyotrophic lateral sclerosis (ALS) is an devastating neurodegenerative disorder with a very fast course and a very high fatality rate. The review discusses the intricate pathophysiology of ALS, such as the alterations caused by the genetic mutations of the C9orf72 and SOD1 genes, the misfolding and aggregation of proteins, oxidative stress, the excitotoxicity of glutamate, neuroinflammation, malfunctions in mitochondria, and axonal transport. Heterogeneity of the disease makes the development of biomarkers in ALS challenging; however, some promising candidates have been identified. Protein aggregation markers, including TDP-43 and SOD1, oxidative stress markers, such as 8-oxodG, neuroinflammatory markers, such as CRP and MCP-1, and neurological injury markers, such as NfL and pNfH, have potential in diagnosis, monitoring, and prediction. The miRNAs and particular metabolites can also provide clues to the molecular basis of ALS. The creation of biomarkers is challenged by the presence of a significant amount of disease heterogeneity and the lack of animal model reliability. The review highlights the importance of further research on biomarkers aimed at improving the diagnosis, treatment, and development of drugs for ALS. It supports the concept of a systematic biomarker development process, including genetic testing and molecular subgroup analysis, to enhance diagnostic accuracy and prognostic prediction capabilities. Exploring the interrelationship between the pathological process of ALS and the treatment based on multi-biomarker strategies is crucial for achieving effective management of this disease. As our understanding of ALS deepens, we expect to discover more new biomarkers in the future. This will significantly improve the diagnosis, treatment, and overall management of this devastating diseas.

ID: 42165374
Title: Lighting Up Mislocalized Proteins: Quantum Dot Probes for Multiplexed Cytoplasm-Selective Cell Profiling in Neurodegeneration.
Abstract: Semiconductor quantum dots (QDs) provide unique stability, brightness, and multiplexed capacity for biomarker detection in complex diseases; however, their distinctive intracellular distribution has rarely been leveraged for spatially resolved diagnostics. Here, we show how QD-based sensors enable selective detection of cytoplasmic proteins and can quantify nucleo-cytoplasm protein mislocalization in patient-derived samples. We validated this approach labeling TAR DNA-binding protein 43 (TDP-43), a key mislocalized protein in amyotrophic lateral sclerosis (ALS). Spatial resolution is achieved in several patient-derived models and mouse brain tissue, underscoring the nanosensor's versatility across biological systems. Multiplexed QD-based immunolabeling, combined with confocal imaging and high-throughput flow cytometry, enables the detection of distinct cytoplasmic biomarker signatures that discriminate ALS patients from healthy controls. These signatures include variations in TDP-43 mislocalization and protein coexpression patterns, which were further modulated by pharmacological treatment. This work establishes QDs as spatially selective, multiplexable nanosensors capable of resolving subtle yet disease-relevant intracellular phenotypes in patient-derived samples. Compared to organic fluorophores, QDs enhance sensitivity, improve signal stability, and enable simultaneous spatially resolved biomarker quantification, broadening their potential for clinical diagnostics and personalized medicine. These findings establish QDs as powerful tools for neurodegeneration research, disease monitoring, and early biomarker discovery, with potential applications in translational neuroscience and precision medicine.

ID: 42178739
Title: Proteomic Analysis of Corpora Amylacea Extracted From Post-mortem Brain of MAiD-end-of-life Sporadic ALS Patients.
Abstract: Corpora amylacea (CA) are starch-like inclusions that accumulate in the central nervous system (CNS) with aging and are enriched in neurodegenerative conditions, including amyotrophic lateral sclerosis (ALS). Although often regarded as waste reservoirs, their cellular origins, molecular composition, and pathological significance remain poorly understood. Here, we performed an unbiased proteomic analysis of purified CAs isolated from post-mortem brains of sporadic ALS patients and controls. In-depth mass spectrometry identified 4,470 proteins, of which 658 were quantified, revealing distinct ALS-specific proteomic signatures. Enriched proteins included markers of cytoskeletal remodeling, mitochondrial dysfunction, and proteostasis disruption, as well as known ALS-associated proteins such as TDP-43 and neurofilament proteins. These findings demonstrate that CAs serve as reservoirs of dysfunctional, disease-relevant proteins and capture key pathological processes in ALS. By applying an unbiased proteomic approach to purified CAs, this study provides the first comprehensive map of their protein content in ALS, supporting their potential as biomarker sources and as a source of mechanistic insights into neurodegeneration. Unbiased analyses of CAs in the context of ALS have yet to be undertaken. This study provides the first proteomic profiling of purified CAs, isolated from ALS patient brains using biochemical methods, revealing that CAs harbor disease-relevant proteins implicated in sporadic ALS. By demonstrating that CAs act as reservoirs of dysfunctional proteins related to metabolism, cytoskeletal organization, and proteostasis, our findings highlight their potential as a novel source of ALS-specific mechanistic insight into disease pathology.

ID: 42182325
Title: C9orf72 -associated G4C2 hexanucleotide repeat expression in Drosophila mushroom bodies causes age dependent TDP-43 pathology and dementia relevant phenotypes mediated in part by the glypican Dlp/GPC6.
Abstract: Hexanucleotide repeat expansions (HREs) in C9orf72 are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), yet the age-, sex-, repeat-length-, and circuit-specific influence on the pathology of neurons remains incompletely understood. Here, we established a Drosophila model of C9orf72 -associated dementia by expressing G4C2 repeats in mushroom body neurons (MBNs), a brain region critical for memory, locomotion, and sleep. Expression of 44X G4C2 repeats ((G4C2) 44X ) led to progressive axonal thinning, age-dependent accumulation of Repeat Associated Non-AUG (RAN) translated GR-GFP dipeptide repeat (DPR) puncta, premature nuclear-to-cytoplasmic mislocalization of endogenous TDP-43, increased caspase, reduced lifespan and a loss of presynaptic active zones. Behaviorally, (G4C2) 44X expression caused locomotor hyperactivity, altered spatial working memory, and fragmentation of sleep architecture in an age- and sex-dependent manner, recapitulating core features of FTD. Surprisingly, the shorter (G4C2) 12X repeat, traditionally considered a control, also produced detectable RAN translation and intermediate phenotypes in aging MBNs, suggesting that length- and tissue-associated factors modulate repeat toxicity. We further identified a repeat-length- and age-dependent reduction of the glypican Dally-like protein (Dlp) in (G4C2) 44X consistent with disrupted Wnt-related signaling linked to TDP-43 proteinopathies. Restoring Dlp expression in MBNs mitigated locomotor and working-memory alterations, and loss of presynaptic active zones. In contrast, axonal degeneration, TDP-43 mislocalization, and lifespan were not significantly improved by restoring Dlp, suggesting that multiple mechanisms contribute to G4C2-induced toxicity. Supporting our findings in Drosophila MBNs, a CRISPRi screen in TDP-43 knock-down iNeurons identified GPC6, a human ortholog of Dlp, as a significant contributor to TDP-43 dependent synaptic loss. Together, our findings reveal an aging-sensitive, circuit-specific model of C9orf72 -associated neurodegeneration and highlight roles for DPR accumulation and Dlp/GPC6 dependent synaptic loss in FTD pathomechanisms.

ID: 42204151
Title: Caspase-4 transgenic mice exhibit cytoplasmic TDP-43 accumulation and age-dependent neuropathology.
Abstract: TAR DNA-binding protein (TDP-43) is a multifunctional protein that binds DNA and RNA within the nucleus. In neurodegenerative diseases like Amyotrophic Lateral Sclerosis (ALS), TDP-43 is mislocalized to the cytoplasm, forming inclusions. Current TDP-43 transgenic mouse models generally fail to exhibit significant cytoplasmic accumulation and loss of nuclear TDP-43, which hampers the investigation of cytoplasmic TDP-43 pathology. We previously discovered that primate-specific caspase-4 (CASP4) can cleave TDP-43, producing truncated fragments that are mislocalized to the cytoplasm. Here we show that a transgenic mouse model that expresses human CASP4 and recapitulates the cytoplasmic mislocalization of endogenous TDP-43 and motor dysfunction in an age-dependent manner. Moreover, CASP4 mice exhibited gene expression changes and neuropathology similar to patients with sporadic ALS. Inhibition of CASP4 by its antisense oligonucleotide ameliorated TDP-43 pathology and subsequent neurotoxicity in CASP4 mice. Thus, CASP4 mice present a valuable animal model for exploring endogenous TDP-43-mediated pathogenesis and therapeutics.

ID: 42222887
Title: Multimodal analysis of cell-free DNA identifies epigenetic biomarkers for amyotrophic lateral sclerosis diagnosis and progression.
Abstract: The role of the epigenome in age-related neurodegenerative disorders remains understudied. Here, we analyzed circulating cell-free DNA (cfDNA) from blood to detect methylation changes as a liquid biopsy for Amyotrophic Lateral Sclerosis (ALS). Our study included 20 patients with sporadic ALS, 10 patients with C9orf72-associated ALS, 10 asymptomatic carriers of the C9orf72 repeat expansion mutation, and 21 nondisease control individuals. Following targeted enzymatic methyl-sequencing (EM-seq) of approximately 4 million CpG sites, we detected numerous differentially methylated genes, including several implicated in ALS disease risk and pathogenesis. By integrating multiple epigenetic features, we delineated a distinct epigenetic signature, which achieved an average area under the curve (AUC) of 0.91 ± 0.10 upon receiver operator characteristic (ROC) analysis, which enabled detection of approximately 70% of patients with ALS with close to 100% specificity. Furthermore, we also identified a set of genes whose methylation status significantly correlated with clinical disease progression and cerebrospinal fluid (CSF) neurofilament levels. Our results reveal the potential of cfDNA-based biomarkers to accurately diagnose ALS and potentially predict disease progression.

ID: 42239172
Title: The retroelement-derived human protein PEG10 is a regulator of mRNA splicing in neurons.
Abstract: Retroelements, including retrotransposons, endogenous retroviruses, and their fragments, as well as rare co-opted or domesticated retroelements, can contribute to neurodegenerative disorders and aging through modulation of gene expression and induction of neuroinflammation. Paternally Expressed Gene 10 (PEG10) is a retroelement-derived human gene that has recently been identified as a putative driver of Amyotrophic Lateral Sclerosis (ALS) and Angelman's Syndrome. PEG10 has been reported to bind nucleic acid and undergoes a complex self-processing pathway that results in gene expression changes when the protein accumulates in cells. Here, we report that PEG10 has selectivity for binding U/G-rich RNAs and influences widespread gene expression changes. PEG10 overexpression mimics the loss of TDP-43 in broad changes to gene expression, including dysregulation of mRNA splicing pathways. Specific changes to mRNA splicing were largely unique between TDP-43 knockdown and PEG10 overexpression, as classic TDP-43 targets including STMN2 were not altered by PEG10. Instead, we identified a unique role for PEG10 in regulating splicing of neuregulin 3 (NRG3), a ligand for the neuronal receptor ERBB4. In SH-SY5Y cells and in human neurons overexpressing PEG10, NRG3 protein levels were decreased along cellular processes, suggesting that these cells are less competent at signaling through the NRG3/ERBB4 axis. Using human patient data, we observed similar changes to NRG3 splicing in UBQLN2-mediated ALS, where PEG10 is accumulated, as well as in some cases of sporadic ALS. In conclusion, the retroelement-derived gene PEG10 plays an unexpected role in regulating splicing of neuronal transcripts, which mimics some of the transcript changes observed in human ALS patient samples. Ultimately, this work has implications for the study of PEG10, and mRNA splicing in neurological diseases associated with elevated PEG10 abundance.

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: 42254864
Title: Human iPSC-derived motor neurons as a platform for elucidating TDP-43-related amyotrophic lateral sclerosis pathogenesis: a mini review.
Abstract: TAR DNA-binding protein 43 (TDP-43) is a major pathogenic RNA-binding protein associated with amyotrophic lateral sclerosis (ALS). Heterozygous mutations in TDP-43 cause familial ALS, known as ALS10. TDP-43 is predominantly localized in the nucleus under physiological conditions. Not only ALS patients with TARDBP mutations but also the majority of sporadic ALS patients exhibit TDP-43 pathology, which is defined by nuclear clearance and cytoplasmic aggregation. The inclusion of cryptic exons in genes such as STMN2 and UNC13A has emerged as a hallmark of TDP-43 loss of function, as demonstrated in TDP-43 knockdown models and postmortem analyses. However, it is not yet clear how TDP-43 levels and location change from healthy to pathological conditions in ALS. Motor neurons derived from induced pluripotent stem cells (iPSCs) have been widely used in ALS research and provide a promising platform to investigate early-stage disease mechanisms. However, challenges remain in generating models that faithfully recapitulate ALS pathogenesis. In this review, we summarize recent advances in TDP-43-related iPSC-derived motor neuron models and discuss future perspectives for elucidating ALS pathogenesis. We propose that longitudinal analyses of TDP-43 dynamics and co-culture systems will be essential to better model early ALS pathogenesis.

ID: 42299014
Title: Pathogenic Proteins Driving ALS Pathogenesis: Molecular Mechanisms and Translational Therapeutic Perspectives.
Abstract: Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of motor neurons, with protein aggregation as a central pathological hallmark. Key pathogenic proteins, including TDP-43, SOD1, FUS, and dipeptide repeat proteins (DPRs) from C9orf72 expansions, drive disease progression through diverse but converging mechanisms. TDP-43 proteinopathy, present in nearly all ALS cases, involves cytoplasmic mislocalization, misfolding, and aggregation, disrupting RNA processing, protein transport, and DNA repair. Similarly, SOD1 and FUS mutations promote toxic protein aggregation, impairing cellular homeostasis and contributing to neuronal dysfunction. C9orf72-derived DPRs exert toxicity by interfering with nucleocytoplasmic transport. The propagation of these pathogenic proteins between neurons and glia, often via prion-like mechanisms, underlies the characteristic spread of ALS pathology throughout the nervous system. Cellular protective responses, such as molecular chaperones and the ubiquitin-proteasome system, attempt to mitigate aggregation but are often overwhelmed in disease states. Mitochondrial dysfunction, oxidative stress, and disturbances in calcium homeostasis are also implicated, with evidence showing that SOD1 mutations can alter redox balance and mitochondrial function in both neurons and non-neuronal cells. Impaired DNA repair mechanisms, involving proteins such as TDP-43, FUS, NEK1, and VCP, have emerged as important contributors to ALS pathogenesis, linking protein aggregation to genomic instability. Recent therapeutic strategies focus on directly targeting misfolded proteins using small molecules, peptides, or antisense oligonucleotides to inhibit aggregation or enhance clearance, offering hope for disease modification. Understanding the interplay between protein aggregation, impaired RNA metabolism, and cellular stress responses is crucial for developing effective translational therapies for ALS.

ID: 42304076
Title: Multi-omic analysis of deep learning-derived phenotypes links ophthalmic imaging to cardiovascular and neurological traits.
Abstract: The eye is a recognized source of biomarkers for cardiovascular and neurodegenerative disease risk. Here we characterize the breadth of these associations and identify biological axes that may mediate them. Using UK Biobank data, we developed a multi-omic analysis pipeline integrating physiological, radiomic, metabolomic and genomic information. We trained retinal adversarial autoencoders to represent optical coherence tomography images and color fundus photographs as 256-dimensional embeddings. Retinal adversarial autoencoder-derived embeddings were associated with a range of cardiovascular and neurodegenerative diseases, including ischemic heart disease, cerebrovascular disease, Parkinson's disease and dementia. Examining associations across diverse omics datasets, we provide evidence linking ophthalmic imaging features to neurological and cardiovascular anatomy and function, lipid metabolism and gene sets associated with neurodegenerative pathology. Collectively, our findings show that ophthalmic features reflect complex, multisystem biological processes and reinforce the role of the eye as a composite indicator of systemic health.

ID: 42304926
Title: Linking Neurodegeneration and Age-related Macular Degeneration: Unified Pathways and Intervention Strategies.
Abstract: Age-related macular degeneration (AMD) is caused by the degeneration of photoreceptors and retinal pigment epithelium (RPE) along with drusen deposition and is the leading cause of vision loss in older adults. Both these structures within the central nervous system (CNS) utilize common neuro-inflammatory mechanisms because the retina is an outgrowth of the brain. Like the brain, the eye has its own physical characteristics and surface molecules as well as a tendency towards specific immune reactions. Numerous distinct neurodegenerative diseases like Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and Frontotemporal dementia (FTD) that impact the brain present as eye symptoms, and the conventional diagnosis of these neurodegenerative disorders (NDs) is often preceded by ocular symptoms. Furthermore, several eye-specific disorders have characteristics in common with other CNS disorders. NDs and AMD share common key features, such as tau and amyloid-β deposits, oxidative stress response, chronic inflammation, and dysregulation of microglia and müller glia. Common pathological mechanisms include complement activation, amyloid aggregation, neuroinflammation, vascular impairment, and cell death, providing a basis for a convergent neuroimmune axis between retinal and cerebral degeneration. Comparing these age-related diseases will facilitate the identification of shared risk factors, convergent molecular pathways, and potential cross-applicable therapeutic strategies, such as anti-inflammatory, anti-complementary, anti-apoptotic, and anti-VEGF-based approaches. This knowledge may enhance understanding of neurodegenerative diseases, help identify early biomarker development for diagnosis, and enable the design of targeted therapeutic strategies.

ID: 42316301
Title: Intrathecal (G4C2)149 delivery in C9orf72-deficient mice yields mild motor dysfunction and ALS/FTD pathological hallmarks.
Abstract: A repeat expansion in C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), yet existing mouse models incompletely engage spinal regions implicated in disease. Here, an adeno-associated virus encoding (G4C2)149 repeats was delivered via neonatal intrathecal injection, achieving widespread CNS expression with robust spinal cord targeting. This approach was applied to mice with graded loss of endogenous C9orf72 to interrogate both gain- and loss-of-function mechanisms. Longitudinal motor, behavioral, and pathological analyses revealed that repeat expression primarily drives mild, progressive muscle weakness, whereas coordination deficits were largely genotype dependent. Subtle gait abnormalities and hyperactivity were also observed. Within spinal motor regions, repeat-expressing mice exhibited dipeptide repeat protein accumulation, reduced NeuN-positive area, fewer motor neurons, glial activation, sparse phosphorylated TDP-43 pathology, and increased cryptic TDP-43 splicing. Cross-domain correlations further linked repeat expression, spinal pathology, and motor dysfunction. Collectively, these findings establish that CNS-wide repeat expression combined with reduced C9orf72 produces a coherent, mild ALS/FTD model.

ID: 42327368
Title: Transcriptomic and pathological analysis of the hnRNP network reveals glial involvement in frontotemporal lobar degeneration pathological subtypes.
Abstract: Frontotemporal dementia is a neurodegenerative disorder with a strong heritable component. Frontotemporal lobar degeneration refers to the pathological changes seen in frontotemporal dementia, characterized by atrophy of the frontal and temporal lobes and the presence of abnormal protein inclusions. In the case of frontotemporal lobar degeneration with hyperphosphorylated TDP-43 positive inclusions (FTLD-TDP), five pathological subtypes (A, B, C, D and E) are observed based on the types and distribution of inclusions found in the brain. In all subtypes, there tends to be a large variability in the number of pathological inclusions observed between cases, with limited correlation to clinical manifestations. TDP-43 is an RNA-binding protein belonging to the heterogeneous nuclear ribonucleoprotein (hnRNP) family, which along with other hnRNPs, modulates multiple aspects of RNA processing. HnRNPs other than TDP-43 have been implicated in several neurological diseases, including Amyotrophic Lateral Sclerosis, FTLD-TDP, frontotemporal lobar degeneration with fused in sarcoma (FTLD-FUS) and Alzheimer's disease. Multiple hnRNPs have been found in pathological inclusions in specific subtypes of FTLD-TDP, suggesting potential roles in the disease process. The role of the hnRNP network in frontotemporal lobar degeneration disease pathogenesis, however, has not yet been investigated. This study aimed to comprehensively evaluate the presence and expression of hnRNP proteins in two pathological subtypes of sporadic FTLD-TDP (A and C) as well as the genetic form FTLD-TDP A C9orf72 using immunohistochemistry and gene expression analysis by single-nuclei RNA-sequencing. We found that there was great variability in the frequency of TDP-43 pathology across and within FTLD-TDP pathological subtypes. Our findings suggest that distinct global transcriptomic profiles may underlie the different pathological subtypes of FTLD-TDP. The most prominent transcriptomic changes were observed in oligodendrocytes and astrocytes, involving multiple hnRNPs across frontotemporal lobar degeneration subtypes compared to controls. Transcriptomic co-expression analysis further revealed that glial clusters were more strongly associated with RNA-processing dysfunction and contributed to disease classification. Together, these findings highlight the involvement of the hnRNP network and glial-specific RNA-processing alterations in FTLD-TDP pathophysiology, offering new insight into the molecular distinctions between pathological subtypes and potential targets for future investigation.

ID: 42337644
Title: Outer nuclear layer thinning as an in vivo biomarker for discriminating probable FTLD-tau from probable FTLD-TDP with PET-supported subtyping.
Abstract: Outer nuclear layer (ONL) thinning has been identified in frontotemporal lobar degeneration (FTLD); however, its utility for distinguishing the subtypes of FTLD-tauopathy (FTLD-tau) and TDP-43 proteinopathy (FTLD-TDP) remains unknown. We investigated whether ONL thickness provides a subtype-informative retinal signal for differentiating PET-supported probable FTLD-tau (pFTLD-tau) from probable FTLD-TDP (pFTLD-TDP) in vivo. Patients clinically diagnosed with FTLD were subtyped into pFTLD-tau and pFTLD-TDP groups based on multimodal PET and clinical criteria. Normal controls (NCs) were cognitively unimpaired on standardized testing and clinical evaluation. Macular images were acquired using swept-source OCT. A custom deep learning algorithm segmented the retina into eight sublayers. The thickness of each retinal sublayer was assessed across the eight sectors of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. Retinal thickness differences were analyzed using generalized estimating equations, and exploratory discrimination models were evaluated using age- and sex-adjusted stepwise logistic regression with apparent and bootstrap optimism-corrected AUCs reported. Exploratory partial correlation analysis was conducted to examine the associations between ONL thickness and cognitive scores. A total of 86 participants were included (21 pFTLD-tau, 27 pFTLD-TDP and 38 NCs). Widespread ONL thinning was observed in pFTLD-tau (Cohen's d= -0.753 to -1.268 vs. controls; -0.666 to -1.069 vs. pFTLD-TDP; all FDR-adjusted P < 0.05), while ONL in pFTLD-TDP remained preserved. A model combining retinal nerve fiber layer (RNFL), ONL, and myoid-ellipsoid zone (MEZ) thickness showed exploratory discrimination for differentiating pFTLD-tau from pFTLD-TDP (apparent AUC, 0.922; optimism-corrected AUC, 0.866). The outer thickness model yielded higher AUC estimates than the inner thickness model (0.884/0.835 vs. 0.713/0.630), and the individual ONL model showed moderate exploratory discrimination (0.808/0.765). ONL thickness was correlated with cognitive scores in pFTLD-tau (partial r = 0.433-0.483; all P < 0.05), whereas corresponding associations in pFTLD-TDP did not reach statistical significance. ONL thinning was preferentially observed in pFTLD-tau and contributed to exploratory discrimination between PET-supported probable FTLD subtypes. These findings suggest that ONL thickness may provide complementary, noninvasive information for probable FTLD subtype stratification, with potential to facilitate therapeutic trial enrollment and personalized management. Future studies incorporating neuropathological confirmation and fluid biomarkers are warranted to validate these findings.

ID: 42353079
Title: Loss of TDP-43 Drives Innate Immune Activation Through Relish in Drosophila.
Abstract: Inflammatory and immune alterations are increasingly recognized as components of ALS pathology, yet whether they arise as a direct consequence of TDP-43 dysfunction or as a downstream response to neurodegeneration remains unresolved. To address this question, we profiled adult head transcriptomes of Drosophila lacking TBPH, the fly homolog of TDP-43, and identified marked overactivation of the conserved Toll/Imd/NF-κB (Relish) innate immune pathway, including increased expression of antimicrobial effector genes and inflammatory genes. We further found that TDP-43/TBPH regulates the NF-κB homolog Relish by associating with its mRNA and that its loss permits Relish-dependent immune overactivation. Genetic reduction in Relish in TDP-43-deficient flies suppressed inflammatory signaling and ameliorated neurological defects in vivo, indicating that immune dysregulation contributes to TDP-43 loss-associated phenotypes.

ID: 42359357
Title: Innate immune crosstalk in ALS/FTD pathogenesis.
Abstract: Marked by protein aggregation, impaired proteostasis, organelle stress, and chronic neuroinflammation, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) form a clinically, genetically, and pathologically overlapping disease spectrum. Increasing evidence indicates that innate immune activation is not merely a secondary response to neuronal injury, but an active driver of disease progression. In this review, we elaborate on how ALS/FTD-associated genetic lesions and pathogenic protein aggregates, including TDP-43, SOD1, FUS, and C9orf72-derived dipeptide repeat proteins, engage three interconnected innate immune pathways: cGAS-STING, NLRP3 inflammasomes, and TREM2-DAP12 signaling. We further highlight emerging crosstalk among these pathways, in which cGAS-STING and NLRP3 reinforce inflammatory signaling, while NLRP3-driven TREM2 shedding may impair microglial clearance and perpetuate proteostatic failure. Understanding this immune network may help define disease subtypes, identify biomarkers, and guide combinatorial therapeutic strategies that suppress harmful inflammation while preserving protective microglial functions.

ID: 42359392
Title: Nonlinear combinatorial analysis of blood transcriptomes identifies PRKAR1A as a regulator of TDP-43 pathophysiology in amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive loss of motor neurons. Accurate and accessible blood-based diagnostics for neurodegenerative diseases, including ALS, are being progressively required. Although blood cell gene expression profiles have potential clinical utility for distinguishing ALS, robust transcriptomic biomarkers for supportive diagnosis have not yet been established. Here, we analyzed publicly available peripheral blood mononuclear cell (PBMC) transcriptomic data from ALS patients using Maximum Mean Discrepancy, a kernel-based method that captures nonlinear distributional differences in a reproducing kernel Hilbert space and enables the extraction of informative gene combinations while minimizing multicollinearity, a common issue in multiple regression models. Using this approach, we identified a nonlinear three-gene combination-PRKAR1A, QPCT, and TMEM71-that distinguished ALS from healthy controls with an area under the curve (AUC) of 0.83 in a public PBMC dataset. This achievement was confirmed in laboratory PBMC samples with an AUC of 0.85, supporting the robustness of the identified gene signature in independent samples. Furthermore, these genes also enabled ALS classification in induced pluripotent stem cell-derived motor neurons with an AUC of 0.79. Knockdown of PRKAR1A, QPCT, or TMEM71 in motor neurons increased the TDP-43 expression levels, and PRKAR1A knockdown induced the mislocalization of TDP-43, accompanied by phosphorylation, suggesting a potential link to ALS-related pathophysiology. These findings suggest that nonlinear gene combinations may provide a useful strategy for identifying blood-based biomarkers and offer insights into ALS pathogenesis. This nonlinear, data-driven analytical framework enabled the transition from unbiased gene discovery to the identification of pathophysiology-associated molecules by in vitro functional validation.

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: 42385702
Title: Recurrent patterns of TOP1-mediated neuronal genomic damage shared by major neurodegenerative disorders.
Abstract: Amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Alzheimer's disease (AD) represent two major categories of neurodegenerative disorders-TAR DNA-binding protein 43 (TDP-43) and tau proteinopathies-for which the mechanisms driving neuronal death remain unclear. Single-cell whole-genome sequencing of 469 neurons from C9ORF72 ALS, C9ORF72 FTD, AD, and control brains revealed increased somatic single-nucleotide variants (sSNVs) and insertions/deletions (sIndels) in all three diseases. Mutational signature analysis identified a disease-associated sSNV signature consistent with oxidative damage and an sIndel process affecting 22% of ALS, 76% of FTD, and 61% of AD neurons-but only 2% of control neurons-resembling signature ID4, previously linked to topoisomerase 1 (TOP1)-mediated mutagenesis. Rapid approach to DNA adduct recovery (RADAR) assays confirmed increased TOP1-DNA covalent complexes, and duplex sequencing confirmed the increased sIndels and identified single-strand events as likely precursor lesions. TOP1-associated sIndel mutagenesis and genome instability thus represent a mechanism shared by both TDP-43 and tau neurodegeneration.

ID: 42392185
Title: [Rare hereditary and acquired diseases with parkinson's syndrome].
Abstract: Despite established clinical diagnostic criteria for Parkinson's disease and the neurodegeneration-related atypical parkinsonian syndromes (progressive supranuclear palsy/PSP, corticobasal degeneration syndrome/CBD, multiple system atrophy with parkinsonian or cerebellar predominance/MSA-P/C, and dementia with Lewy bodies/DLB), the differential diagnosis from rare hereditary and acquired disorders presenting with parkinsonism can be challenging. Based on a PubMed search, relevant original studies and review articles were analyzed to identify rare hereditary and acquired disorders associated with parkinsonism. Secondary parkinsonian syndromes resulting from medication or toxin exposure were excluded but are summarized in an overview. Without claiming completeness, the major hereditary and acquired disorders associated with parkinsonism were summarized in tabular form. Selected entities were described in more detail in short profiles focusing on those with therapeutic modifiability, characteristic pattern-like constellations of findings, or notable pathophysiological mechanisms. Paradigmatic cerebral MRI patterns are illustrated. A broad spectrum of rare acquired and genetic entities can manifest with clinically relevant parkinsonian syndromes. Frequently, parkinsonism occurs in combination with other neurological features of variable severity, including extrapyramidal-hyperkinetic symptoms (dystonia/chorea), cerebellar signs (ataxia), pontomesencephalic involvement (oculomotor disturbances, bulbar dysarthria/dysphagia), motor neuron signs (spasticity and/or amyotrophic paresis), cognitive or neuropsychiatric symptoms, and epilepsy.For several disease groups - such as neurodegeneration with brain iron accumulation (NBIA), Wilson's disease, and primary familial brain calcification (PFBC) - distinctive MRI patterns are diagnostically informative.A relevant subset of disorders exhibits at least a partial and sometimes transient presynaptic dopaminergic deficit responsive to dopaminergic medication (e.g., certain NBIA forms, spinocerebellar ataxias/SCA, cerebrotendinous xanthomatosis/CTX).Neuropathologically, some of these disorders are associated with secondary synucleinopathies (e.g., MPAN), tauopathies (e.g., IgLON5 syndrome) or TDP-43 (e.g., Perry syndrome/DCTN1). Trotz klinischer diagnostischer Kriterien für die Parkinson-Krankheit sowie die neurodegenerativ bedingten atypischen Parkinson-Syndrome (PSP, CBD, MSA-P/C sowie LBD) kann die Differentialdiagnose zu seltenen hereditären und erworbenen Erkrankungen mit Parkinson-Syndrom schwierig sein.Es wurden seltene hereditäre und erworbene Erkrankungen mit Parkinson-Syndrom ausgewählt. Sekundäre Parkinson-Syndrome als Folge von Medikation oder Toxin-Exposition wurden ausgeklammert und nur im systematischen Überblick mit dargestellt.Ohne Anspruch auf Vollständigkeit wurden die wesentlichen hereditären und erworbenen Erkrankungen mit Parkinson-Syndrom tabellarisch zusammengefasst. Einzelne ausgewählte Entitäten wurden in Form kurzer Steckbriefe detaillierter beschrieben. Hierfür ausgewählt wurden Entitäten mit therapeutischer Beeinflussbarkeit, besonderen Muster-artigen Befundkonstellationen und interessanten pathophysiologischen Zusammenhängen. Zudem wurden paradigmatische zerebrale MRT-Muster einzelner Entitäten dargestellt.Es existiert eine Vielzahl seltener erworbener und genetischer Entitäten mit klinisch relevanten Parkinson-Syndromen. Häufig tritt das Parkinson-Syndrom dabei mit zusätzlichen anderen klinischen Affektionen (extrapyramidal-hyperkinetisch: Dystonie/Chorea; zerebellär: Ataxie; pontomesencephal: Okulomotorikstörungen, bulbäre Dysarthrie/Dysphagie; Motoneurone: Spastik und/oder myatrophe Paresen; Demenz/neuropsychiatrische Symptomatik; Epilepsie) in variabler Kombination und Schweregradausprägung auf. Für einige Erkrankungsgruppen (z.B. Neurodegeneration mit Eisenablagerung/NBIA, M. Wilson, Primäre Familiäre Hirnkalzifikation/PFBC) ist das bildgebende MRT-Muster diagnostisch wegweisend. Eine relevante Anzahl von Erkrankungen weist ein therapeutisch zumindest partiell und zeitlich vorübergehend mittels dopaminerger Medikation beeinflussbares präsynaptisches dopaminerges Defizit (z.B. einige NBIA-Formen, SCA-Formen, CTX) auf. Pathophysiologisch treten bei einigen Erkrankungen sekundär pathologische Proteinaggregate (z.B. MPAN: Synukleinopathie; IgLON5-Syndrom: Tauopathie; Perry-Syndrom/DCTN1: TDP-43 Aggregate) auf.

ID: 42399370
Title: Therapeutic targeting of the conserved region within the low-complexity domain of TDP-43 is neuroprotective and extends survival in amyotrophic lateral sclerosis mice.
Abstract: Autosomal dominant mutations in TARDBP, encoding TAR DNA-binding protein 43 (TDP-43), cause amyotrophic lateral sclerosis (ALS), and TDP-43 pathology is a hallmark of multiple aging-associated neurodegenerative diseases. Despite its pathological role, effective therapies remain limited by the lack of safe, potent molecules targeting TDP-43 neurotoxicity. Here we show that the conserved α-helical region spanning residues 320-340 (conserved region or CR) is a therapeutically actionable target for TDP-43 neurotoxicity. Deletion of CR markedly suppressed TDP-43-induced neuronal death. Structure-based virtual screening identified XL20, a brain-penetrant small molecule that engages CR and confers neuroprotection without affecting TDP-43 splicing activity. XL20 alleviated motor neuron loss, extended survival in TDP-43 p.Ala315Thr ALS mice and enhanced neuronal function in p.Gln331Lys induced pluripotent stem cell-derived human ALS motor neurons. Mechanistically, targeting CR suppressed TDP-43 mitochondrial localization and restored mitochondrial function, likely through liquid-liquid phase separation. Our findings highlight CR as a therapeutic target for TDP-43-associated neurodegeneration and support CR-binding small molecules as therapeutic candidates.

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.