Neuropathological validation studies of pathology-specific biomarkers for neurodegenerative diseases are essential but are often limited by long sampling-to-death intervals and the lack of semi-quantitative pathology measures. We assessed the associations of five cerebrospinal fluid (CSF) (Aβ42/Aβ40, p-tau181, p-tau217, Aβ42/p-tau181 and Aβ42/p-tau217) and three plasma (p-tau217, p-tau217/Aβ42 and Aβ42/Aβ40) biomarkers with post-mortem Aβ and tau pathology burden in 250 participants with ante-mortem CSF (n=230) and/or plasma (n=101), affected by prion (n=162) or non-prion diseases (n=88). Aβ and tau burden were scored across nine and six brain areas, respectively. We assessed the earliest biomarker changes across quartiles of Aβ and tau pathology burden and the discriminatory performance at progressively higher pathology thresholds using multivariable linear regression and sequential ROC analyses. Analyses on p-tau markers were restricted to non-prion participants. The median sampling-death interval was 1.5 months for CSF and 1 month for plasma. CSF Aβ42/Aβ40 decreased at the second quartile of Aβ burden (p<0.001), whereas p-tau181 (p<0.01) and p-tau217 (p<0.001) increased only from the third quartile. CSF Aβ42/Aβ40 achieved its highest accuracy at low/intermediate Aβ burden (AUC 0.984), while CSF p-tau and derived ratios performed best at advanced Aβ (AUCs 0.889 to 0.980) and intermediate tau pathology stages (AUCs 0.949 to 0.995). CSF p-tau217 and Aβ42/p-tau217 consistently showed higher accuracy than their p-tau181 counterparts across Aβ and tau pathology scores. Plasma p-tau217 and p-tau217/Aβ42 significantly increased in the highest Aβ and tau burden quartiles, where they achieved their best performance (AUCs 0.893 to 0.928). These findings support a sequential model of biomarker changes across the Alzheimer’s disease neuropathological continuum. CSF Aβ42/Aβ40 best reflects low/intermediate Aβ burden, while CSF p-tau markers are more closely related to high Aβ and intermediate tau load. Plasma markers primarily identify advanced Aβ and tau pathology burden. Notably, current fluid biomarkers do not capture the earliest phases of Aβ deposition.
ARPP21 has recently emerged as a new amyotrophic lateral sclerosis (ALS) associated gene but its pathogenic role remains unclear. In this study we performed familial, clinical, neuropathological and cellular analyses to characterize the recurrent p.P529L and p.P713L variants (also known as p.P563L variant and p.P747L variant, respectively) in our French ALS cohort of 1190 ALS cases and 50 additional family members available for segregation analysis, resulting in the description of 29 ARPP21-linked patients. ARPP21 emerged as the most frequent rare ALS-associated gene in France after exclusion of the four major ALS genes, accounting for 2.7
Mutations in superoxide dismutase−1 (SOD1) are a common cause of amyotrophic lateral sclerosis (ALS). Inheritance is as a rule dominant, but in carriers of the most prevalent mutation, D90A, disease primarily develops in homozygotes. Increasing evidence suggests that prion-like propagation of SOD1 aggregation is the central pathogenic mechanism. Two structurally different strains of aggregates have been found to arise in human SOD1 (hSOD1) transgenic (Tg) mouse models of ALS. Strain A is formed by most mutants including hSOD1G85R and homozygous hSOD1WT Tg mice, whereas homozygous hSOD1D90A Tg mice form a distinct strain B, but also A. Inoculation of strain A and B seed preparations from Tg mice into lumbar spinal cord of adult hSOD1G85R mice induced templated spreading hSOD1 aggregation and premature ALS-like disease. Seeds from an ALS patient carrying the hSOD1G127X truncation mutation likewise transmitted strain A aggregation and disease. In the present study, we investigated whether seeds prepared from spinal ventral horns from six patients homozygous for the hSOD1D90A mutation could transmit aggregation and disease to adult hSOD1G85R Tg mice. Despite the extensive degeneration and loss of motor neurons in the long-lived D90A patients, two of the seeds significantly shortened the survival of the Tg mice, one transmitting A and the other B-pattern hSOD1 aggregation. Nine different preparations from four human controls lacked effects. The results demonstrate that two distinct aggregate strains can arise and propagate in homozygous hSOD1D90A ALS patients, further supporting the hypothesis that prion-like transmission of hSOD1 aggregation is the primary pathogenic mechanism in SOD1-linked ALS.
The pathophysiological mechanisms underlying the hypercoagulable state and thrombotic events associated with COVID-19 remain incompletely understood. To investigate prothrombotic alterations during SARS-CoV-2 infection, we performed an exploratory and integrated analysis of cerebral thrombi retrieved, during the first wave of the pandemic, by mechanical thrombectomy from stroke patients with (n=6) and without (n=6) COVID-19. We combined histological and ultrastructural assessment with quantitative proteomics and elemental profiling to identify differences in cellular organization and in protein and metal composition. Immunohistochemical quantification revealed a trend toward increased macrophage abundance, a more diffuse CD68⁺ staining pattern, and reduced platelet content in COVID-19 thrombi. In contrast, neutrophil extracellular traps (NETs) burden, neutrophil number, and erythrocyte content did not differ significantly between groups. Transmission electron microscopy showed a disorganized ultrastructural fibrillar network in thrombi from COVID-19 stroke patients, consistent with the irregular and less densely packed extracellular matrix observed by Masson's trichrome staining. Furthermore, quantitative proteomics by liquid chromatography–tandem mass spectrometry (LC–MS/MS) identified 48 differentially expressed proteins among 720 shared proteins, with marked upregulation of hemoglobin subunits (α, β, γ, and δ), haptoglobin, biliverdin reductase and redox-regulating proteins, alongside downregulation of platelet-related proteins in COVID-19 thrombi. Total reflection X-ray fluorescence (TXRF) confirmed increased iron levels in COVID-19-associated thrombi. Notably, glycophorin A immunostaining did not indicate increased erythrocyte abundance, and erythrocyte structural proteins were not differentially expressed in proteomic analysis, suggesting that hemoglobin and iron were largely present in a cell-free form within the retrieved thrombi of COVID-19 stroke patients. In addition, acute-phase reactants, classical complement components, and immunoglobulins were detected exclusively in COVID-19 samples, consistent with a distinctive immune-inflammatory and oxidative signature. Overall, these findings support a novel pathophysiological mechanism underlying COVID-19-associated hypercoagulability and thrombosis, involving elevated circulating cell-free hemoglobin and increased iron content. Furthermore, this study highlights the potential contribution of hemoglobin/iron-related processes to the COVID-19 prothrombotic state and may provide molecular targets for future therapeutic strategies.
Pediatric central nervous system tumors remain a leading cause of cancer-related mortality in children, while their diagnosis, risk stratification, and therapeutic management increasingly depend on integrated molecular characterization. However, representative tumor tissue is often difficult to obtain because of tumor location, surgical risk, limited biopsy material, and the impracticality of repeated sampling during disease evolution. Cerebrospinal fluid (CSF) has therefore emerged as a particularly informative liquid biopsy compartment for many CNS malignancies, enriched in tumor-derived cell-free DNA and, for tumors in contact with the CSF spaces, more directly reflective of intracranial tumor biology than plasma; its yield nonetheless varies with tumor biology and anatomical proximity to CSF pathways. Here, we review the evidence supporting CSF cell-free DNA sequencing as an emerging extension of molecular neuropathology in pediatric CNS tumors. Targeted next-generation sequencing, low-pass whole-genome sequencing, methylation-based classifiers, and nanopore sequencing now enable complementary assessment of somatic mutations, copy number alterations, epigenetic tumor class, and longitudinal tumor burden from low-input pediatric CSF samples. Recent studies have moved the field beyond analytical proof of concept towards defined clinical scenarios, including molecular diagnosis when biopsy is infeasible, molecular staging of high-CSF-shedding tumors, minimal residual disease monitoring in medulloblastoma and other embryonal tumors, and clarification of ambiguous radiological progression. CSF-based sequencing does not replace tissue neuropathology, but provides a liquid molecular layer that can complement, extend, or in selected situations partially substitute tissue-based diagnosis. Its broader adoption now depends on workflow standardization, assay-specific reporting standards, external quality assurance, and prospective evidence that CSF-guided decisions improve patient outcomes.
Histopathologic staging models of neuronal α-synuclein pathology (n-asyn) in Lewy body disease (LBD) seldom evaluate brain regions with direct synaptic connectivity to model the role of microglial processes. We address this gap by testing the hypothesis that, within the well-defined synaptic connectivity of the intrahippocampal circuit, n-asyn is associated with activated microglial phenotypes. We selected a cohort of autopsy-confirmed LBD patients and minimal age-related copathologies (n = 62) and a control cohort of cognitively healthy patients with isolated hippocampal tau accumulation (i.e., primary age-related tauopathy, PART; n = 12), to control for neurodegenerative pathology without amyloid plaques. We immunostained consecutive hippocampal sections for n-asyn and established markers of activated microglial phenotypes, Iba1, HLA-DR, and CD68. With validated digital histology methods, we measured percent area occupied (
In multiple sclerosis (MS), the chronic, unresolved nature of neuroinflammation within the central nervous system (CNS) remains a major obstacle for effective therapeutic intervention. This challenge arises primarily due to an incomplete understanding of the dysregulated inflammatory and pro-resolving pathways underlying MS lesion progression. Bioactive lipid mediators (LMs), biosynthesized through the coordinated actions of specific enzymes like lipoxygenases (LOX) and cyclooxygenases (COX), are key regulators of both the initiation and resolution of an inflammatory response; however, their spatial organization and functional role during MS pathology have not been fully elucidated. Here, by using pneumatically assisted nanospray desorption electrospray ionization (PA nano-DESI) mass spectrometry imaging and immunohistochemistry, we reveal an increase in the LM leukotriene B4 (LTB4) in human MS white matter compared to controls, with further enrichment in MS lesions relative to perilesional areas, alongside elevated microglial 5-LOX activating protein (FLAP) expression. Pharmacological antagonism of FLAP suppresses LTB4 biosynthesis in human-induced pluripotent stem cell (iPSC)-derived microglia with only marginal effects on the microglia transcriptional phenotype as determined by RNA sequencing. Moreover, in vivo FLAP antagonism ameliorates disease severity and spinal cord inflammatory gene expression in the experimental autoimmune encephalomyelitis (EAE) model, an animal model of MS, in both a prophylactic and therapeutic settings. This coincided with reduced local LTB4 biosynthesis and reduced levels of inflammatory monocytes within the spinal cord during EAE. Together these findings establish the FLAP/LTB4 axis as a driver of neuroinflammation and a druggable therapeutic target for chronic inflammatory CNS disorders like MS.
Glioblastoma remains a challenging disease to approach with immunotherapy due to pronounced antigen heterogeneity, immunosuppressive tumor microenvironment, and barriers to effective molecule delivery within the central nervous system. T-cell engagers provide an off-the-shelf approach to redirect endogenous T cells toward tumor cells. However, bispecific formats are constrained by intra- and interpatient antigen heterogeneity, which can limit therapeutic efficacy. In this review, we examine trispecific T-cell engagers (TriTEs) as an emerging strategy to address this limitation by simultaneously targeting multiple tumor-associated antigens. We discuss principles guiding antigen selection in glioblastoma, summarize available preclinical evidence supporting multispecific engagement, and outline key design considerations, including molecular architecture, stability, half-life extension, and safety optimization. We further review delivery strategies, such as gene-encoded expression, cellular carriers, and blood–brain barrier modulation, that may improve tumor access and the durability of TriTEs. Together, these considerations position TriTEs as a modular immunotherapy platform relevant to glioblastoma and other heterogeneous solid tumors.
Alzheimer's disease (AD) is characterised by the intraneuronal aggregation of phosphorylated Tau (pTau) into neurofibrillary tangles and by the extracellular deposition of β-amyloid (Aβ). Tau pathology restricted to the hippocampal formation is frequently observed in the elderly brain in the absence of any Aβ deposition and considered as "primary age-related tauopathy" (PART). Here, we applied an unbiased proteomic approach to determine how concomitant Aβ pathology modifies the neurofibrillary tangle proteome. Neurofibrillary tangles were isolated by dissecting Tau pSer202/pThr205 "AT8" immunopositive neuronal profiles, combining chromogenic immunohistochemistry with laser capture microdissection, from hippocampal sections of 17 post-mortem brains spanning three groups: PART (n = 5; A0, B1-2, C0 scores), intermediate AD (n = 6; A1-2, B2-3, C1-2 scores) and advanced AD (n = 6; A3, B3, C3 scores). A label-free quantitative liquid chromatography-mass spectrometry based proteomic analysis, using data independent acquisition (DIA) on a Bruker timsTOF, was performed. A conserved core of 63 proteins was identified as enriched in tangles across all groups, mostly associated with "RNA binding" and "regulation of mRNA metabolic process", based on the Gene Ontology database. Group-specific signatures were also observed: 33 proteins were significantly enriched only in tangles collected from PART cases and were predominantly linked to "structural molecule activity", whereas Aβ-positive cases showed specific enrichment of "RNA binding" and "cytoplasmic translation" pathways-with intermediate AD cases displaying a transitional profile. Our findings are consistent with PART having distinct tangle proteomic features; however, the majority of its proteomic signature is in common with tangles within the AD continuum. By addressing how Aβ accumulation alters the tangle proteome, this study provides mechanistic insights into the expansion of Tau pathology, paving the way towards the identification of biomarkers and therapeutic strategies that would allow for stabilisation of Tau pathology in the elderly.
Mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE) is a recently defined malformation of cortical development that is an important cause of childhood-onset drug-resistant epilepsy. Clinically, the epilepsies associated with MOGHE are heterogeneous, with infantile epileptic spasms syndrome (IESS) being the most common manifestation. Histopathologically, MOGHE demonstrates subtle cortical dyslamination, heterotopic neurons in the white matter, hypomyelination, and a distinctive increase in the density and clustering of oligodendroglial cells, features that distinguish it from other malformations of cortical development such as focal cortical dysplasia (FCD). Recent genetic analyses of epileptogenic tissue resected from individuals with MOGHE have identified somatic mosaic loss-of-function variants in SLC35A2. This gene encodes the Golgi transmembrane UDP-galactose transporter, suggesting disrupted N-glycosylation as a distinct pathogenic mechanism underlying epilepsy in this disorder. In this review, we present the current clinical, histopathological, and molecular understanding of MOGHE, with a particular focus on recent insights gained from experimental rodent and human cellular models of SLC35A2 deficiency. We contextualise these findings against established models of mTORopathies including FCD type 2, placing MOGHE within the broader malformation of cortical development spectrum. Synthesising this evidence, we observe that neuronal activity in models of both MOGHE and mTORopathies such as FCD type 2 converge on reduced action potential firing, despite their distinct genetic aetiologies. Finally, we discuss how these findings inform our understanding of epileptogenesis, especially the emergence of infantile epileptic spasms, and the development of future precision therapeutic strategies across malformations of cortical development.
Alzheimer’s disease (AD) is characterised by the intraneuronal aggregation of phosphorylated Tau (pTau) into neurofibrillary tangles and by the extracellular deposition of β-amyloid (Aβ). Tau pathology restricted to the hippocampal formation is frequently observed in the elderly brain in the absence of any Aβ deposition and considered as “primary age-related tauopathy” (PART). Here, we applied an unbiased proteomic approach to determine how concomitant Aβ pathology modifies the neurofibrillary tangle proteome. Neurofibrillary tangles were isolated by dissecting Tau pSer202/pThr205 “AT8” immunopositive neuronal profiles, combining chromogenic immunohistochemistry with laser capture microdissection, from hippocampal sections of 17 post-mortem brains spanning three groups: PART (n = 5; A0, B1–2, C0 scores), intermediate AD (n = 6; A1–2, B2–3, C1–2 scores) and advanced AD (n = 6; A3, B3, C3 scores). A label-free quantitative liquid chromatography–mass spectrometry based proteomic analysis, using data independent acquisition (DIA) on a Bruker timsTOF, was performed. A conserved core of 63 proteins was identified as enriched in tangles across all groups, mostly associated with “RNA binding” and “regulation of mRNA metabolic process”, based on the Gene Ontology database. Group-specific signatures were also observed: 33 proteins were significantly enriched only in tangles collected from PART cases and were predominantly linked to “structural molecule activity”, whereas Aβ-positive cases showed specific enrichment of “RNA binding” and “cytoplasmic translation” pathways—with intermediate AD cases displaying a transitional profile. Our findings are consistent with PART having distinct tangle proteomic features; however, the majority of its proteomic signature is in common with tangles within the AD continuum. By addressing how Aβ accumulation alters the tangle proteome, this study provides mechanistic insights into the expansion of Tau pathology, paving the way towards the identification of biomarkers and therapeutic strategies that would allow for stabilisation of Tau pathology in the elderly.
Chordomas are rare cancers that arise along the axial skeleton. Alterations in metabolism are a hallmark of cancer, and we sought to identify metabolic vulnerabilities in chordoma. We discovered that the tricarboxylic acid (TCA)-related enzyme isocitrate dehydrogenase-1 (IDH1) was expressed highly in bulk and single-cell patient-derived chordomas and was associated with worse survival outcomes. IDH1 catalyzes the conversion of isocitrate and nicotinamide adenine dinucleotide phosphate (NADP+) to alpha-ketoglutarate (⍺-KG) and NADPH. This critical reaction influences TCA cycle metabolism, regulates epigenetic pathways, and affects redox balance. Both IDH1 knockdown and treatment with an inhibitor targeting IDH1 were toxic to chordoma cells. An integrated analysis of the transcriptomic, chromatin, and metabolomic responses on IDH1 inhibition converged on deregulated glutathione metabolism. IDH1 inhibition was associated with increased expression and enrichment of activating H3K27ac at NRF2 (nuclear factor erythroid 2-related factor 2) signature genes including those in the glutathione biosynthetic pathway. This was accompanied by reduction of both NADPH/NADP+ and reduced/oxidized glutathione (GSH/GSSG) ratios. Importantly, IDH1 inhibitor-driven toxicity was rescued via media supplementation with the antioxidant N-acetylcysteine, suggesting that IDH1 inhibition in chordomas creates a redox-dependent metabolic vulnerability. Finally, IDH1 inhibitor treatment reduced tumor growth in two independent chordoma mouse xenograft models. Our findings suggest a potential therapeutic avenue for further exploration in chordoma.
Cerebral amyloid angiopathy (CAA) is a common brain pathology in older people and has been recently recognized as a major risk factor for amyloid-related imaging abnormalities during anti-amyloid antibody therapy. CAA pathophysiology may involve iron released from ruptured vessels, but the association between postmortem CAA and brain iron is unclear. This study investigates the association between CAA and brain iron and whether elevated iron modifies the association between CAA and cognitive decline. We studied 626 Rush Memory and Aging Project decedents (mean age at death = 90 [SD = 6.1] years, 70
Autosomal-dominant frontotemporal lobar degeneration with tau pathology (FTLD-tau) is caused by pathogenic variants in the MAPT gene. Although abnormal tau aggregation is a shared endpoint, MAPT mutations produce distinct cellular phenotypes and regional patterns of tau deposition, the mutation specificity and familial consistency of which remain poorly defined. We performed a systematic neuropathologic and transcriptomic analysis of brains from clinically characterized families carrying MAPT V337M, P301L, or L284L mutations. Multiple affected members per family were examined, with interfamily comparisons for P301L. Quantitative assessment of regional tau burden, cellular morphology, and co-pathologies revealed distinct, mutation-specific signatures. The V337M mutation was characterized by predominantly neuronal tau pathology with vesicular pretangles, scattered neurofibrillary tangles, and fine neurites, with minimal glial involvement. P301L exhibited prominent astrocytic tau pathology, including globular and proximal inclusions, accompanied by neuronal pretangles. L284L produced extensive oligodendroglial tau pathology with thick fibrillar coiled bodies in gray and white matter. Additional distinguishing features included hippocampal sclerosis and TDP-43 pathology in V337M; severe cortical neuronal loss and dentate fascia tau in P301L; and extensive white matter and brainstem tau, including ventral pontine neurons, in L284L. These morphologic profiles were conserved within families and, for P301L, across unrelated families. Transcriptomic analyses suggested mutation-linked expression changes concordant with cellular pathology. These findings define reproducible, mutation-specific neuropathologic and molecular signatures of MAPT-associated FTLD-tau, emphasizing the importance of genotype-driven stratification in studies of tauopathy pathogenesis.
Atypical teratoid/rhabdoid tumors (AT/RT) are the most common malignant brain tumors during infancy and associated with a dismal prognosis. The majority of patients suffer from tumor progression or recurrence, but underlying mechanisms remain unknown. To better understand such mechanisms, we performed single-nucleus RNA sequencing (snRNAseq) of eight paired primary tumors and recurrences. Tumor cells and cells of the tumor microenvironment (TME) were analyzed separately. Potentially therapy-resistant tumor cells were identified through the comparison of global gene expression profiles between primary and recurrent tumor cell populations using CIBERSORT. Histopathology, in vitro experiments, bulk RNA sequencing, and survival analysis were performed for validation. Paired primary and recurrent AT/RT showed significant differences in their gene expression profiles. Potentially therapy-resistant AT/RT-MYC tumor cells revealed changes in the extracellular matrix (ECM) as well as altered developmental processes and immune signaling pathways. Respective gene signatures were correlated with inferior survival in AT/RT-MYC patients. Tumor cells of relapsed AT/RT-MYC underwent partial epithelial-mesenchymal transition (pEMT), a feature that was confirmed by immunohistochemistry (IHC) and by analyzing AT/RT cells after standard therapy in vitro. Together, we identified potential mechanisms of tumor relapse and therapy resistance in AT/RT, which could be employed to improve therapy in future.
Multiple system atrophy (MSA) is a rapidly progressive synucleinopathy of unknown aetiology with neuronal and oligodendroglial α-synuclein inclusions. We previously reported somatic copy number variants (CNVs), specifically gains of SNCA (encoding α-synuclein) in MSA brains. Here, we expand on this work by combining fluorescent in situ hybridisation for SNCA on nuclei with α-synuclein and SOX10 immunofluorescence, to assess oligodendrocyte-specific SNCA gains and losses, and their relationship with inclusions across differentially affected regions in two MSA subtypes: striatonigral degeneration (SND) and olivopontocerebellar atrophy (OPCA). Analysis of 13 SND, 12 OPCA and 15 control brains demonstrated significantly higher somatic SNCA CNVs, both gains and losses, in MSA oligodendrocytes compared with controls (gains: 6.3
