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Neuronal dysfunction due to iron accumulation in conjunction with reactive oxygen species (ROS) could represent an important, yet underappreciated, component of the epileptogenic process. However, to date, alterations in iron metabolism in the epileptogenic brain have not been addressed in detail. Iron-related neuropathology and antioxidant metabolic processes were investigated in resected brain tissue from patients with temporal lobe epilepsy and hippocampal sclerosis (TLE-HS), post-mortem brain tissue from patients who died after status epilepticus (SE) as well as brain tissue from the electrically induced SE rat model of TLE. Magnetic susceptibility of the presumed seizure-onset zone from three patients with focal epilepsy was compared during and after seizure activity. Finally, the cellular effects of iron overload were studied in vitro using an acute mouse hippocampal slice preparation and cultured human fetal astrocytes. While iron-accumulating neurons had a pyknotic morphology, astrocytes appeared to acquire iron-sequestrating capacity as indicated by prominent ferritin expression and iron retention in the hippocampus of patients with SE or TLE. Interictal to postictal comparison revealed increased magnetic susceptibility in the seizure-onset zone of epilepsy patients. Post-SE rats had consistently higher hippocampal iron levels during the acute and chronic phase (when spontaneous recurrent seizures are evident). In vitro, in acute slices that were exposed to iron, neurons readily took up iron, which was exacerbated by induced epileptiform activity. Human astrocyte cultures challenged with iron and ROS increased their antioxidant and iron-binding capacity, but simultaneously developed a pro-inflammatory phenotype upon chronic exposure. These data suggest that seizure-mediated, chronic neuronal iron uptake might play a role in neuronal dysfunction/loss in TLE-HS. On the other hand, astrocytes sequester iron, specifically in chronic epilepsy. This function might transform astrocytes into a highly resistant, pro-inflammatory phenotype potentially contributing to pro-epileptogenic inflammatory processes. Supplementary Information The online version contains supplementary material available at 10.1007/s00401-021-02348-6.

Heterogeneous nuclear ribonucleoproteins (HnRNPs) are a group of ubiquitously expressed RNA-binding proteins implicated in the regulation of all aspects of nucleic acid metabolism. HnRNP K is a member of this highly versatile hnRNP family. Pathological redistribution of hnRNP K to the cytoplasm has been linked to the pathogenesis of several malignancies but, until now, has been underexplored in the context of neurodegenerative disease. Here we show hnRNP K mislocalisation in pyramidal neurons of the frontal cortex to be a novel neuropathological feature that is associated with both frontotemporal lobar degeneration and ageing. HnRNP K mislocalisation is mutually exclusive to TDP-43 and tau pathological inclusions in neurons and was not observed to colocalise with mitochondrial, autophagosomal or stress granule markers. De-repression of cryptic exons in RNA targets following TDP-43 nuclear depletion is an emerging mechanism of potential neurotoxicity in frontotemporal lobar degeneration and the mechanistically overlapping disorder amyotrophic lateral sclerosis. We silenced hnRNP K in neuronal cells to identify the transcriptomic consequences of hnRNP K nuclear depletion. Intriguingly, by performing RNA-seq analysis we find that depletion of hnRNP K induces 101 novel cryptic exon events. We validated cryptic exon inclusion in an SH-SY5Y hnRNP K knockdown and in FTLD brain exhibiting hnRNP K nuclear depletion. We, therefore, present evidence for hnRNP K mislocalisation to be associated with FTLD and for this to induce widespread changes in splicing. Supplementary Information The online version contains supplementary material available at 10.1007/s00401-021-02340-0.

Progressive supranuclear palsy (PSP) is the second most common neurodegenerative Parkinsonian disorder after Parkinson’s disease, and is characterized as a primary tauopathy. Leveraging the considerable clinical and neuropathologic heterogeneity associated with PSP, we measured tau neuropathology as quantitative traits to perform a genome-wide association study (GWAS) within PSP to identify genes and biological pathways that underlie the PSP disease process. In 882 PSP cases, semi-quantitative scores for phosphorylated tau-immunoreactive coiled bodies (CBs), neurofibrillary tangles (NFTs), tufted astrocytes (TAs), and tau threads were documented from 18 brain regions, and converted to latent trait (LT) variables using the R ltm package. LT analysis utilizes a multivariate regression model that links categorical responses to unobserved covariates allowing for a reduction of dimensionality, generating a single, continuous variable to account for the multiple lesions and brain regions assessed. We first tested for association with PSP LTs and the top PSP GWAS susceptibility loci. Significant SNP/LT associations were identified at rs242557 (MAPT H1c sub-haplotype) with hindbrain CBs and rs1768208 (MOBP) with forebrain tau threads. Digital microscopy was employed to quantify phosphorylated tau burden in midbrain tectum and red nucleus in 795 PSP cases and tau burdens were used as quantitative phenotypes in GWAS. Top associations were identified at rs1768208 with midbrain tectum and red nucleus tau burden. Additionally, we performed a PSP LT GWAS on an initial cohort, a follow-up SNP panel (37 SNPs, P –5) in an extended cohort, and a combined analysis. Top SNP/LT associations were identified at SNPs in or near SPTBN5/EHD4, SEC13/ATP2B2, EPHB1/PPP2R3A, TBC1D8, IFNGR1/OLIG3, ST6GAL1, HK1, CALB1, and SGCZ. Finally, testing for SNP/transcript associations using whole transcriptome and whole genome data identified significant expression quantitative trait loci at rs3088159/SPTBN5/EHD4 and rs154239/GHRL. Modeling tau neuropathology heterogeneity using LTs as quantitative phenotypes in a GWAS may provide substantial insight into biological pathways involved in PSP by affecting regional tau burden.

Granulovacuolar degeneration (GVD) is a common feature in Alzheimer’s disease (AD). The occurrence of GVD is closely associated with that of neurofibrillary tangles (NFTs) and GVD is even considered to be a pre-NFT stage in the disease process of AD. Currently, the composition of GVD bodies, the mechanisms associated with GVD and how GVD exactly relates to NFTs is not well understood. By combining immunohistochemistry (IHC) and laser microdissection (LMD) we isolated neurons with GVD and those bearing tangles separately from human post-mortem AD hippocampus (n = 12) using their typical markers casein kinase (CK)1δ and phosphorylated tau (AT8). Control neurons were isolated from cognitively healthy cases (n = 12). 3000 neurons per sample were used for proteome analysis by label free LC–MS/MS. In total 2596 proteins were quantified across samples and a significant change in abundance of 115 proteins in GVD and 197 in tangle bearing neurons was observed compared to control neurons. With IHC the presence of PPIA, TOMM34, HSP70, CHMP1A, TPPP and VXN was confirmed in GVD containing neurons. We found multiple proteins localizing specifically to the GVD bodies, with VXN and TOMM34 being the most prominent new protein markers for GVD bodies. In general, protein groups related to protein folding, proteasomal function, the endolysosomal pathway, microtubule and cytoskeletal related function, RNA processing and glycolysis were found to be changed in GVD neurons. In addition to these protein groups, tangle bearing neurons show a decrease in ribosomal proteins, as well as in various proteins related to protein folding. This study, for the first time, provides a comprehensive human based quantitative assessment of protein abundances in GVD and tangle bearing neurons. In line with previous functional data showing that tau pathology induces GVD, our data support the model that GVD is part of a pre-NFT stage representing a phase in which proteostasis and cellular homeostasis is disrupted. Elucidating the molecular mechanisms and cellular processes affected in GVD and its relation to the presence of tau pathology is highly relevant for the identification of new drug targets for therapy. Supplementary Information The online version contains supplementary material available at 10.1007/s00401-020-02261-4.

The microtubule-associated protein tau (tau) forms hyperphosphorylated aggregates in the brains of tauopathy patients that can be pathologically and biochemically defined as distinct tau strains. Recent studies show that these tau strains exhibit strain-specific biological activities, also referred to as pathogenicities, in the tau spreading models. Currently, the specific pathogenicity of human-derived tau strains cannot be fully recapitulated by synthetic tau preformed fibrils (pffs), which are generated from recombinant tau protein. Reproducing disease-relevant tau pathology in cell and animal models necessitates the use of human brain-derived tau seeds. However, the availability of human-derived tau is extremely limited. Generation of tau variants that can mimic the pathogenicity of human-derived tau seeds would significantly extend the scale of experimental design within the field of tauopathy research. Previous studies have demonstrated that in vitro seeding reactions can amplify the beta-sheet structure of tau protein from a minute quantity of human-derived tau. However, whether the strain-specific pathogenicities of the original, human-derived tau seeds are conserved in the amplified tau strains has yet to be experimentally validated. Here, we used biochemically enriched brain-derived tau seeds from Alzheimer’s disease (AD), corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) patient brains with a modified seeding protocol to template the recruitment of recombinant 2N4R (T40) tau in vitro. We quantitatively interrogated efficacy of the amplification reactions and the pathogenic fidelity of the amplified material to the original tau seeds using recently developed sporadic tau spreading models. Our data suggest that different tau strains can be faithfully amplified in vitro from tau isolated from different tauopathy brains and that the amplified tau variants retain their strain-dependent pathogenic characteristics. Supplementary Information The online version contains supplementary material available at 10.1007/s00401-020-02253-4.

Schwannomatosis (SWNTS) is a genetic cancer predisposition syndrome that manifests as multiple and often painful neuronal tumors called schwannomas (SWNs). While germline mutations in SMARCB1 or LZTR1, plus somatic mutations in NF2 and loss of heterozygosity in chromosome 22q have been identified in a subset of patients, little is known about the epigenomic and genomic alterations that drive SWNTS-related SWNs (SWNTS-SWNs) in a majority of the cases. We performed multiplatform genomic analysis and established the molecular signature of SWNTS-SWNs. We show that SWNTS-SWNs harbor distinct genomic features relative to the histologically identical non-syndromic sporadic SWNs (NS-SWNS). We demonstrate the existence of four distinct DNA methylation subgroups of SWNTS-SWNs that are associated with specific transcriptional programs and tumor location. We show several novel recurrent non-22q deletions and structural rearrangements. We detected the SH3PXD2A-HTRA1 gene fusion in SWNTS-SWNs, with predominance in LZTR1-mutant tumors. In addition, we identified specific genetic, epigenetic, and actionable transcriptional programs associated with painful SWNTS-SWNs including PIGF, VEGF, MEK, and MTOR pathways, which may be harnessed for management of this syndrome.

Specificity and sensitivity of positron emission tomography (PET) radiopharmaceuticals targeting fibrillar amyloid-β (Aβ) deposits is high for detection of neuritic Aβ plaques, a mature form of Aβ deposits which often have dense Aβ core (i.e., cored plaques). However, imaging-to-autopsy validation studies of amyloid PET radioligands have identified several false positive cases all of which had mainly diffuse Aβ plaques (i.e., plaques without neuritic pathology or dense amyloid core), and high amyloid PET signal was reported in the striatum where diffuse plaques predominate in Alzheimer’s disease (AD). Relative contributions of different plaque types to amyloid PET signal is unclear, particularly in neocortical areas where they are intermixed in AD. In vitro binding assay and autoradiography were performed using [3H]flutemetamol and [3H]Pittsburgh Compound-B (PiB) in frozen brain homogenates from 30 autopsy cases including sporadic AD and non-AD controls with a range of brain Aβ burden and plaque density. Fixed tissue sections of frontal cortex and caudate from 10 of the AD cases were processed for microscopy using fluorescent derivatives of flutemetamol (cyano-flutemetamol) and PiB (cyano-PiB) and compared to Aβ immunohistochemistry and pan-amyloid (X-34) histology. Using epifluorescence microscopy, percent area coverage and fluorescence output values of cyano-PiB- and cyano-flutemetamol-labeled plaques in two-dimensional microscopic fields were then calculated and combined to obtain integrated density measurements. Using confocal microscopy, we analysed total fluorescence output of the entire three-dimensional volume of individual cored plaques and diffuse plaques labeled with cyano-flutemetamol or cyano-PiB. [3H]Flutemetamol and [3H]PiB binding values in tissue homogenates correlated strongly and their binding pattern in tissue sections, as seen on autoradiograms, overlapped the pattern of Aβ-immunoreactive plaques on directly adjacent sections. Cyano-flutemetamol and cyano-PiB fluorescence was prominent in cored plaques and less so in diffuse plaques. Across brain regions and cases, percent area coverage of cyano-flutemetamol-labeled plaques correlated strongly with cyano-PiB-labeled and Aβ-immunoreactive plaques. For both ligands, plaque burden, calculated as percent area coverage of all Aβ plaque types, was similar in frontal cortex and caudate regions, while integrated density values were significantly greater in frontal cortex, which contained both cored plaques and diffuse plaques, compared to the caudate, which contained only diffuse plaques. Three-dimensional analysis of individual plaques labeled with either ligand showed that total fluorescence output of a single cored plaque was equivalent to total fluorescence output of approximately three diffuse plaques of similar volume. Our results indicate that [18F]flutemetamol and [11C]PiB PET signal is influenced by both diffuse plaques and cored plaques, and therefore is likely a function of plaque size and density of Aβ fibrils in plaques. Brain areas with large volumes/frequencies of diffuse plaques could yield [18F]flutemetamol and [11C]PiB PET retention levels comparable to brain regions with a lower volume/frequency of cored plaques.

The proinflammatory cytokine interleukin 1 (IL-1) is crucially involved in the pathogenesis of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Herein, we studied the role of IL-1 signaling in blood–brain barrier (BBB) endothelial cells (ECs), astrocytes and microglia for EAE development, using mice with the conditional deletion of its signaling receptor IL-1R1. We found that IL-1 signaling in microglia and astrocytes is redundant for the development of EAE, whereas the IL-1R1 deletion in BBB-ECs markedly ameliorated disease severity. IL-1 signaling in BBB-ECs upregulated the expression of the adhesion molecules Vcam-1, Icam-1 and the chemokine receptor Darc, all of which have been previously shown to promote CNS-specific inflammation. In contrast, IL-1R1 signaling suppressed the expression of the stress-responsive heme catabolizing enzyme heme oxygenase-1 (HO-1) in BBB-ECs, promoting disease progression via a mechanism associated with deregulated expression of the IL-1-responsive genes Vcam1, Icam1 and Ackr1 (Darc). Mechanistically, our data emphasize a functional crosstalk of BBB-EC IL-1 signaling and HO-1, controlling the transcription of downstream proinflammatory genes promoting the pathogenesis of autoimmune neuroinflammation. Electronic supplementary material The online version of this article (10.1007/s00401-020-02187-x) contains supplementary material, which is available to authorized users.

Sporadic Creutzfeldt–Jakob disease (sCJD) is a transmissible brain proteinopathy. Five main clinicopathological subtypes (sCJD-MM(V)1, -MM(V)2C, -MV2K, -VV1, and -VV2) are currently distinguished. Histopathological evidence suggests that the localisation of prion aggregates and spongiform lesions varies among subtypes. Establishing whether there is an initial site with detectable imaging abnormalities (epicentre) and an order of lesion propagation would be informative for disease early diagnosis, patient staging, management and recruitment in clinical trials. Diffusion magnetic resonance imaging (MRI) is the most-used and most-sensitive test to detect spongiform degeneration. This study was designed to identify, in vivo and for the first time, subtype-dependent epicentre and lesion propagation in the brain using diffusion-weighted images (DWI), in the largest known cross-sectional dataset of autopsy-proven subjects with sCJD. We estimate lesion propagation by cross-sectional DWI using event-based modelling, a well-established data-driven technique. DWI abnormalities of 594 autopsy-diagnosed subjects (448 patients with sCJD) were scored in 12 brain regions by 1 neuroradiologist blind to the diagnosis. We used the event-based model to reconstruct sequential orderings of lesion propagation in each of five pure subtypes. Follow-up data from 151 patients validated the estimated sequences. Results showed that epicentre and ordering of lesion propagation are subtype specific. The two most common subtypes (-MM1 and -VV2) showed opposite ordering of DWI abnormality appearance: from the neocortex to subcortical regions, and vice versa, respectively. The precuneus was the most likely epicentre also in -MM2 and -VV1 although at variance with -MM1, abnormal signal was also detected early in cingulate and insular cortices. The caudal-rostral sequence of lesion propagation that characterises -VV2 was replicated in -MV2K. Combined, these data-driven models provide unprecedented dynamic insights into subtype-specific epicentre at onset and propagation of the pathologic process, which may also enhance early diagnosis and enable disease staging in sCJD.

Tau protein accumulation is a common denominator of major dementias, but this process is inhomogeneous, even when triggered by the same germline mutation. We considered stochastic misfolding of human tau conformers followed by templated conversion of native monomers as an underlying mechanism and derived sensitive conformational assays to test this concept. Assessments of brains from aged TgTauP301L transgenic mice revealed a prodromal state and three distinct signatures for misfolded tau. Frontotemporal lobar degeneration (FTLD)-MAPT-P301L patients with different clinical phenotypes also displayed three signatures, two resembling those found in TgTauP301L mice. As physicochemical and cell bioassays confirmed diverse tau strains in the mouse and human brain series, we conclude that evolution of diverse tau conformers is intrinsic to the pathogenesis of this uni-allelic form of tauopathy. In turn, effective therapeutic interventions in FTLD will need to address evolving repertoires of misfolded tau species rather than singular, static molecular targets. Electronic supplementary material The online version of this article (10.1007/s00401-020-02148-4) contains supplementary material, which is available to authorized users.

We sought to define the pathological features of myelin oligodendrocyte glycoprotein (MOG) antibody associated disorders (MOGAD) in an archival autopsy/biopsy cohort. We histopathologically analyzed 2 autopsies and 22 brain biopsies from patients with CNS inflammatory demyelinating diseases seropositive for MOG-antibody by live-cell-based-assay with full length MOG in its conformational form. MOGAD autopsies (ages 52 and 67) demonstrate the full spectrum of histopathological features observed within the 22 brain biopsies (median age, 10 years; range, 1–66; 56% female). Clinical, radiologic, and laboratory characteristics and course (78% relapsing) are consistent with MOGAD. MOGAD pathology is dominated by coexistence of both perivenous and confluent white matter demyelination, with an over-representation of intracortical demyelinated lesions compared to typical MS. Radially expanding confluent slowly expanding smoldering lesions in the white matter as seen in MS, are not present. A CD4+ T-cell dominated inflammatory reaction with granulocytic infiltration predominates. Complement deposition is present in all active white matter lesions, but a preferential loss of MOG is not observed. AQP4 is preserved, with absence of dystrophic astrocytes, and variable oligodendrocyte and axonal destruction. MOGAD is pathologically distinguished from AQP4-IgG seropositive NMOSD, but shares some overlapping features with both MS and ADEM, suggesting a transitional pathology. Complement deposition in the absence of selective MOG protein loss suggest humoral mechanisms are involved, however argue against endocytic internalization of the MOG antigen. Parallels with MOG-EAE suggest MOG may be an amplification factor that augments CNS demyelination, possibly via complement mediated destruction of myelin or ADCC phagocytosis.

Pericyte loss and deficient vascular platelet-derived growth factor receptor-β (PDGFRβ) signaling are prominent features of the blood–brain barrier breakdown described in Alzheimer’s disease (AD) that can predict cognitive decline yet have never been studied in the retina. Recent reports using noninvasive retinal amyloid imaging, optical coherence tomography angiography, and histological examinations support the existence of vascular-structural abnormalities and vascular amyloid β-protein (Aβ) deposits in retinas of AD patients. However, the cellular and molecular mechanisms of such retinal vascular pathology were not previously explored. Here, by modifying a method of enzymatically clearing non-vascular retinal tissue and fluorescent immunolabeling of the isolated blood vessel network, we identified substantial pericyte loss together with significant Aβ deposition in retinal microvasculature and pericytes in AD. Evaluation of postmortem retinas from a cohort of 56 human donors revealed an early and progressive decrease in vascular PDGFRβ in mild cognitive impairment (MCI) and AD compared to cognitively normal controls. Retinal PDGFRβ loss significantly associated with increased retinal vascular Aβ40 and Aβ42 burden. Decreased vascular LRP-1 and early apoptosis of pericytes in AD retina were also detected. Mapping of PDGFRβ and Aβ40 levels in pre-defined retinal subregions indicated that certain geometrical and cellular layers are more susceptible to AD pathology. Further, correlations were identified between retinal vascular abnormalities and cerebral Aβ burden, cerebral amyloid angiopathy (CAA), and clinical status. Overall, the identification of pericyte and PDGFRβ loss accompanying increased vascular amyloidosis in Alzheimer’s retina implies compromised blood–retinal barrier integrity and provides new targets for AD diagnosis and therapy. Electronic supplementary material The online version of this article (10.1007/s00401-020-02134-w) contains supplementary material, which is available to authorized users.

Mid-life hypertension and cerebrovascular dysfunction are associated with increased risk of later life dementia, including Alzheimer’s disease (AD). The classical renin–angiotensin system (cRAS), a physiological regulator of blood pressure, functions independently within the brain and is overactive in AD. cRAS-targeting anti-hypertensive drugs are associated with reduced incidence of AD, delayed onset of cognitive decline, and reduced levels of Aβ and tau in both animal models and human pathological studies. cRAS activity is moderated by a downstream regulatory RAS pathway (rRAS), which is underactive in AD and is strongly associated with pathological hallmarks in human AD, and cognitive decline in animal models of CNS disease. We now show that enhancement of brain ACE2 activity, a major effector of rRAS, by intraperitoneal administration of diminazene aceturate (DIZE), an established activator of ACE2, lowered hippocampal Aβ and restored cognition in mid-aged (13–14-month-old) symptomatic Tg2576 mice. We confirmed that the protective effects of DIZE were directly mediated through ACE2 and were associated with reduced hippocampal soluble Aβ42 and IL1-β levels. DIZE restored hippocampal MasR levels in conjunction with increased NMDA NR2B and downstream ERK signalling expression in hippocampal synaptosomes from Tg2576 mice. Chronic (10 weeks) administration of DIZE to pre-symptomatic 9–10-month-old Tg2576 mice, and acute (10 days) treatment in cognitively impaired 12–13-month-old mice, prevented the development of cognitive impairment. Together these data demonstrate that ACE2 enhancement protects against and reverses amyloid-related hippocampal pathology and cognitive impairment in a preclinical model of AD. Electronic supplementary material The online version of this article (10.1007/s00401-019-02098-6) contains supplementary material, which is available to authorized users.

The current classification of sporadic Creutzfeldt–Jakob disease (sCJD) includes six major clinicopathological subtypes defined by the physicochemical properties of the protease-resistant core of the pathologic prion protein (PrPSc), defining two major PrPSc types (i.e., 1 and 2), and the methionine (M)/valine (V) polymorphic codon 129 of the prion protein gene (PRNP). How these sCJD subtypes relate to the well-documented phenotypic heterogeneity of genetic CJD (gCJD) is not fully understood. We analyzed molecular and phenotypic features in 208 individuals affected by gCJD, carrying 17 different mutations, and compared them with those of a large series of sCJD cases. We identified six major groups of gCJD based on the combination PrPSc type and codon 129 genotype on PRNP mutated allele, each showing distinctive histopathological characteristics, irrespectively of the PRNP associated mutation. Five gCJD groups, named M1, M2C, M2T, V1, and V2, largely reproduced those previously described in sCJD subtypes. The sixth group shared phenotypic traits with the V2 group and was only detected in patients carrying the E200K-129M haplotype in association with a PrPSc type of intermediate size (“i”) between type 1 and type 2. Additional mutation-specific effects involved the pattern of PrP deposition (e.g., a “thickened” synaptic pattern in E200K carriers, cerebellar “stripe-like linear granular deposits” in those with insertion mutations, and intraneuronal globular dots in E200K-V2 or -M”i”). A few isolated cases linked to rare PRNP haplotypes (e.g., T183A-129M), showed atypical phenotypic features, which prevented their classification into the six major groups. The phenotypic variability of gCJD is mostly consistent with that previously found in sCJD. As in sCJD, the codon 129 genotype and physicochemical properties of PrPSc significantly correlated with the phenotypic variability of gCJD. The most common mutations linked to CJD appear to have a variable and overall less significant effect on the disease phenotype, but they significantly influence disease susceptibility often in a strain-specific manner. The criteria currently used for sCJD subtypes can be expanded and adapted to gCJD to provide an updated classification of the disease with a molecular basis.

Granulovacuolar degeneration bodies (GVBs) are membrane-bound vacuolar structures harboring a dense core that accumulate in the brains of patients with neurodegenerative disorders, including Alzheimer’s disease and other tauopathies. Insight into the origin of GVBs and their connection to tau pathology has been limited by the lack of suitable experimental models for GVB formation. Here, we used confocal, automated, super-resolution and electron microscopy to demonstrate that the seeding of tau pathology triggers the formation of GVBs in different mouse models in vivo and in primary mouse neurons in vitro. Seeding-induced intracellular tau aggregation, but not seed exposure alone, causes GVB formation in cultured neurons, but not in astrocytes. The extent of tau pathology strongly correlates with the GVB load. Tau-induced GVBs are immunoreactive for the established GVB markers CK1δ, CK1ɛ, CHMP2B, pPERK, peIF2α and pIRE1α and contain a LAMP1- and LIMP2-positive single membrane that surrounds the dense core and vacuole. The proteolysis reporter DQ-BSA is detected in the majority of GVBs, demonstrating that GVBs contain degraded endocytic cargo. GFP-tagged CK1δ accumulates in the GVB core, whereas GFP-tagged tau or GFP alone does not, indicating selective targeting of cytosolic proteins to GVBs. Taken together, we established the first in vitro model for GVB formation by seeding tau pathology in primary neurons. The tau-induced GVBs have the marker signature and morphological characteristics of GVBs in the human brain. We show that GVBs are lysosomal structures distinguished by the accumulation of a characteristic subset of proteins in a dense core. Electronic supplementary material The online version of this article (10.1007/s00401-019-02046-4) contains supplementary material, which is available to authorized users.

Glioblastomas (GBMs) are malignant central nervous system (CNS) neoplasms with a very poor prognosis. They display cellular hierarchies containing self-renewing tumourigenic glioma stem cells (GSCs) in a complex heterogeneous microenvironment. One proposed GSC niche is the extracellular matrix (ECM)-rich perivascular bed of the tumour. Here, we report that the ECM binding dystroglycan (DG) receptor is expressed and functionally glycosylated on GSCs residing in the perivascular niche. Glycosylated αDG is highly expressed and functional on the most aggressive mesenchymal-like (MES-like) GBM tumour compartment. Furthermore, we found that DG acts to maintain an MES-like state via tight control of MAPK activation. Antibody-based blockade of αDG induces robust ERK-mediated differentiation leading to reduced GSC potential. DG was shown to be required for tumour initiation in MES-like GBM, with constitutive loss significantly delaying or preventing tumourigenic potential in-vivo. These findings reveal a central role of the DG receptor, not only as a structural element, but also as a critical factor promoting MES-like GBM and the maintenance of GSCs residing in the perivascular niche. Electronic supplementary material The online version of this article (10.1007/s00401-019-02069-x) contains supplementary material, which is available to authorized users.

The conversion of endogenous alpha-synuclein (asyn) to pathological asyn-enriched aggregates is a hallmark of Parkinson’s disease (PD). These inclusions can be detected in the central and enteric nervous system (ENS). Moreover, gastrointestinal symptoms can appear up to 20 years before the diagnosis of PD. The dual-hit hypothesis posits that pathological asyn aggregation starts in the ENS, and retrogradely spreads to the brain. In this study, we tested this hypothesis by directly injecting preformed asyn fibrils into the duodenum wall of wild-type rats and transgenic rats with excess levels of human asyn. We provide a meticulous characterization of the bacterial artificial chromosome (BAC) transgenic rat model with respect to initial propagation of pathological asyn along the parasympathetic and sympathetic pathways to the brainstem, by performing immunohistochemistry at early time points post-injection. Induced pathology was observed in all key structures along the sympathetic and parasympathetic pathways (ENS, autonomic ganglia, intermediolateral nucleus of the spinal cord (IML), heart, dorsal motor nucleus of the vagus, and locus coeruleus (LC)) and persisted for at least 4 months post-injection. In contrast, asyn propagation was not detected in wild-type rats, nor in vehicle-injected BAC rats. The presence of pathology in the IML, LC, and heart indicate trans-synaptic spread of the pathology. Additionally, the observed asyn inclusions in the stomach and heart may indicate secondary anterograde propagation after initial retrograde spreading. In summary, trans-synaptic propagation of asyn in the BAC rat model is fully compatible with the “body-first hypothesis” of PD etiopathogenesis. To our knowledge, this is the first animal model evidence of asyn propagation to the heart, and the first indication of bidirectional asyn propagation via the vagus nerve, i.e., duodenum-to-brainstem-to-stomach. The BAC rat model could be very valuable for detailed mechanistic studies of the dual-hit hypothesis, and for studies of disease modifying therapies targeting early pathology in the gastrointestinal tract. Electronic supplementary material The online version of this article (10.1007/s00401-019-02040-w) contains supplementary material, which is available to authorized users.

Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB) are clinically and neuropathologically highly related α-synucleinopathies that collectively constitute the second leading cause of neurodegenerative dementias. Genetic and neuropathological studies directly implicate α-synuclein (αS) abnormalities in PDD and DLB pathogenesis. However, it is currently unknown how αS abnormalities contribute to memory loss, particularly since forebrain neuronal loss in PDD and DLB is less severe than in Alzheimer’s disease. Previously, we found that familial Parkinson’s disease-linked human mutant A53T αS causes aberrant localization of the microtubule-associated protein tau to postsynaptic spines in neurons, leading to postsynaptic deficits. Thus, we directly tested if the synaptic and memory deficits in a mouse model of α-synucleinopathy (TgA53T) are mediated by tau. TgA53T mice exhibit progressive memory deficits associated with postsynaptic deficits in the absence of obvious neuropathological and neurodegenerative changes in the hippocampus. Significantly, removal of endogenous mouse tau expression in TgA53T mice (TgA53T/mTau−/−), achieved by mating TgA53T mice to mouse tau-knockout mice, completely ameliorates cognitive dysfunction and concurrent synaptic deficits without affecting αS expression or accumulation of selected toxic αS oligomers. Among the known tau-dependent effects, memory deficits in TgA53T mice were associated with hippocampal circuit remodeling linked to chronic network hyperexcitability. This remodeling was absent in TgA53T/mTau−/− mice, indicating that postsynaptic deficits, aberrant network hyperactivity, and memory deficits are mechanistically linked. Our results directly implicate tau as a mediator of specific human mutant A53T αS-mediated abnormalities related to deficits in hippocampal neurotransmission and suggest a mechanism for memory impairment that occurs as a consequence of synaptic dysfunction rather than synaptic or neuronal loss. We hypothesize that these initial synaptic deficits contribute to network hyperexcitability which, in turn, exacerbate cognitive dysfunction. Our results indicate that these synaptic changes present potential therapeutic targets for amelioration of memory deficits in α-synucleinopathies. Electronic supplementary material The online version of this article (10.1007/s00401-019-02032-w) contains supplementary material, which is available to authorized users.

Chronic traumatic encephalopathy (CTE) is reported at high prevalence in selected autopsy case series of former contact sports athletes. Nevertheless, the contribution of CTE pathology to clinical presentation and its interaction with co-morbid neurodegenerative pathologies remain unclear. To address these issues, we performed comprehensive neuropathology assessments on the brains of former athletes with dementia and considered these findings together with detailed clinical histories to derive an integrated clinicopathological diagnosis for each case. Consecutive, autopsy-acquired brains from former soccer and rugby players with dementia were assessed for neurodegenerative pathologies using established and preliminary consensus protocols. Thereafter, next of kin interviews were conducted to obtain detailed accounts of the patient's clinical presentation and course of disease to inform a final, integrated clinicopathological diagnosis. Neuropathologic change consistent with CTE (CTE-NC) was confirmed in five of seven former soccer and three of four former rugby players' brains, invariably in combination with mixed, often multiple neurodegenerative pathologies. However, in just three cases was the integrated dementia diagnosis consistent with CTE, the remainder having alternate diagnoses, with the most frequent integrated diagnosis Alzheimer's disease (AD) (four cases; one as mixed AD and vascular dementia). This consecutive autopsy series identifies neuropathologic change consistent with preliminary diagnostic criteria for CTE (CTE-NC) in a high proportion of former soccer and rugby players dying with dementia. However, in the majority, CTE-NC appears as a co-morbidity rather than the primary, dementia causing pathology. As such, we suggest that while CTE-NC might be common in former athletes with dementia, in many cases its clinical significance remains uncertain.

The intercellular transfer of alpha-synuclein (α-syn) has been implicated in the progression of Parkinson’s disease (PD) and multiple system atrophy (MSA). The cellular mechanisms underlying this process are now beginning to be elucidated. In this study, we demonstrate that the gap junction protein connexin-32 (Cx32) is centrally involved in the preferential uptake of α-syn oligomeric assemblies (oα-syn) in neurons and oligodendrocytes. In vitro, we demonstrate a clear correlation between Cx32 expression and oα-syn uptake. Pharmacological and genetic strategies targeting Cx32 successfully blocked oα-syn uptake. In cellular and transgenic mice modeling PD and MSA, we observed significant upregulation of Cx32 which correlates with α-syn accumulation. Notably, we could also demonstrate a direct interaction between α-syn and Cx32 in two out of four human PD cases that was absent in all four age-matched controls. These data are suggestive of a link between Cx32 and PD pathophysiology. Collectively, our results provide compelling evidence for Cx32 as a novel target for therapeutic intervention in PD and related α-synucleinopathies. Electronic supplementary material The online version of this article (10.1007/s00401-019-02007-x) contains supplementary material, which is available to authorized users.

There is a fundamental gap in understanding the consequences of tau–ribosome interactions. Tau oligomers and filaments hinder protein synthesis in vitro, and they associate strongly with ribosomes in vivo. Here, we investigated the consequences of tau interactions with ribosomes in transgenic mice, in cells, and in human brain tissues to identify tau as a direct modulator of ribosomal selectivity. First, we performed microarrays and nascent proteomics to measure changes in protein synthesis. Using regulatable rTg4510 tau transgenic mice, we determined that tau expression differentially shifts both the transcriptome and the nascent proteome, and that the synthesis of ribosomal proteins is reversibly dependent on tau levels. We further extended these results to human brains and found that tau pathologically interacts with ribosomal protein S6 (rpS6 or S6), a crucial regulator of translation. Consequently, protein synthesis under translational control of rpS6 was reduced under tauopathic conditions in Alzheimer’s disease brains. Our data establish tau as a driver of RNA translation selectivity. Moreover, since regulation of protein synthesis is critical for learning and memory, aberrant tau–ribosome interactions in disease could explain the linkage between tauopathies and cognitive impairment. Electronic supplementary material The online version of this article (10.1007/s00401-019-01970-9) contains supplementary material, which is available to authorized users.

A GGGGCC hexanucleotide repeat expansion within the C9orf72 gene is the most common genetic cause of both amyotrophic lateral sclerosis and frontotemporal dementia. Sense and antisense repeat-containing transcripts undergo repeat-associated non-AUG-initiated translation to produce five dipeptide proteins (DPRs). The polyGR and polyPR DPRs are extremely toxic when expressed in Drosophila neurons. To determine the mechanism that mediates this toxicity, we purified DPRs from the Drosophila brain and used mass spectrometry to identify the in vivo neuronal DPR interactome. PolyGR and polyPR interact with ribosomal proteins, and inhibit translation in both human iPSC-derived motor neurons, and adult Drosophila neurons. We next performed a screen of 81 translation-associated proteins in GGGGCC repeat-expressing Drosophila to determine whether this translational repression can be overcome and if this impacts neurodegeneration. Expression of the translation initiation factor eIF1A uniquely rescued DPR-induced toxicity in vivo, indicating that restoring translation is a potential therapeutic strategy. These data directly implicate translational repression in C9orf72 repeat-induced neurodegeneration and identify eIF1A as a novel modifier of C9orf72 repeat toxicity. Electronic supplementary material The online version of this article (10.1007/s00401-018-1946-4) contains supplementary material, which is available to authorized users.

Meningeal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is a rare tumor with propensity for recurrence and metastasis. Although multiple classification schemes have been proposed, optimal risk stratification remains unclear, and the prognostic impact of fusion status is uncertain. We compared the 2016 WHO CNS tumor grading scheme (CNS-G), a three-tier system based on histopathologic phenotype and mitotic count, to the 2013 WHO soft-tissue counterpart (ST-G), a two-tier system based on mitotic count alone, in a cohort of 133 patients [59 female, 74 male; mean age 54 years (range 20–87)] with meningeal SFT/HPC. Tumors were pathologically confirmed through review of the first tumor resection (n = 97), local recurrence (n = 35), or distant metastasis (n = 1). A STAT6 immunostain showed nuclear expression in 132 cases. NAB2–STAT6 fusion was detected in 99 of 111 successfully tested tumors (89%) including the single STAT6 immunonegative tumor. Tumors were classified by CNS-G as grade 1 (n = 43), 2 (n = 41), or 3 (n = 49), and by ST-G as SFT (n = 84) or malignant SFT (n = 49). Necrosis was present in 16 cases (12%). On follow-up, 42 patients had at least one subsequent recurrence or metastasis (7 metastasis only, 33 recurrence only, 2 patients had both). Twenty-nine patients died. On univariate analysis, necrosis (p = 0.002), CNS-G (p = 0.01), and ST-G (p = 0.004) were associated with recurrence-free (RFS) but not overall survival (OS). NAB2–STAT6 fusion type was not significantly associated with RFS or OS, but was associated with phenotype. A modified ST-G incorporating necrosis showed higher correlation with RFS (p = 0.0006) and remained significant (p = 0.02) when considering only the primary tumors. From our data, mitotic rate and necrosis appear to stratify this family of tumors most accurately and could be incorporated in a future grading scheme. Electronic supplementary material The online version of this article (10.1007/s00401-018-1952-6) contains supplementary material, which is available to authorized users.

Stroke attracts neutrophils to the injured brain tissue where they can damage the integrity of the blood–brain barrier and exacerbate the lesion. However, the mechanisms involved in neutrophil transmigration, location and accumulation in the ischemic brain are not fully elucidated. Neutrophils can reach the perivascular spaces of brain vessels after crossing the endothelial cell layer and endothelial basal lamina of post-capillary venules, or migrating from the leptomeninges following pial vessel extravasation and/or a suggested translocation from the skull bone marrow. Based on previous observations of microglia phagocytosing neutrophils recruited to the ischemic brain lesion, we hypothesized that microglial cells might control neutrophil accumulation in the injured brain. We studied a model of permanent occlusion of the middle cerebral artery in mice, including microglia- and neutrophil-reporter mice. Using various in vitro and in vivo strategies to impair microglial function or to eliminate microglia by targeting colony stimulating factor 1 receptor (CSF1R), this study demonstrates that microglial phagocytosis of neutrophils has fundamental consequences for the ischemic tissue. We found that reactive microglia engulf neutrophils at the periphery of the ischemic lesion, whereas local microglial cell loss and dystrophy occurring in the ischemic core are associated with the accumulation of neutrophils first in perivascular spaces and later in the parenchyma. Accordingly, microglia depletion by long-term treatment with a CSF1R inhibitor increased the numbers of neutrophils and enlarged the ischemic lesion. Hence, microglial phagocytic function sets a critical line of defense against the vascular and tissue damaging capacity of neutrophils in brain ischemia., Supported by grants of the Ministerio de Economía y Competitividad (MINECO) (SAF2014-56279-R and SAF2017-87459-R).

Alzheimer disease (AD) and chronic traumatic encephalopathy (CTE) involve the abnormal accumulation in the brain of filaments composed of both three-repeat (3R) and four-repeat (4R) (3R/4R) tau isoforms. To probe the molecular basis for AD’s tau filament propagation and to improve detection of tau aggregates as potential biomarkers, we have exploited the seeded polymerization growth mechanism of tau filaments to develop a highly selective and ultrasensitive cell-free tau seed amplification assay optimized for AD (AD real-time quaking-induced conversion or AD RT-QuIC). The reaction is based on the ability of AD tau aggregates to seed the formation of amyloid fibrils made of certain recombinant tau fragments. AD RT-QuIC detected seeding activity in AD (n = 16) brains at dilutions as extreme as 107–1010-fold, but was 102–106-fold less responsive when seeded with brain from most cases of other types of tauopathy with comparable loads of predominant 3R or 4R tau aggregates. For example, AD brains had average seeding activities that were orders of magnitude higher than Pick disease brains with predominant 3R tau deposits, but the opposite was true using our previously described Pick-optimized tau RT-QuIC assay. CTE brains (n = 2) had seed concentrations comparable to the weakest of the AD specimens, and higher than 3 of 4 specimens with 3R/4R primary age-related tauopathy. AD seeds shared properties with the tau filaments found in AD brains, as AD seeds were sarkosyl-insoluble, protease resistant, and reactive with tau antibodies. Moreover, AD RT-QuIC detected as little as 16 fg of pure synthetic tau fibrils. The distinctive seeding activity exhibited by AD and CTE tau filaments compared to other types of tauopathies in these seeded polymerization reactions provides a mechanistic basis for their consistent propagation as specific conformers in patients with 3R/4R tau diseases. Importantly, AD RT-QuIC also provides rapid ultrasensitive quantitation of 3R/4R tau-seeding activity as a biomarker. Electronic supplementary material The online version of this article (10.1007/s00401-018-1947-3) contains supplementary material, which is available to authorized users.

Meniere’s disease (MD), a syndromal inner ear disease, is commonly associated with a pathological accumulation of endolymphatic fluid in the inner ear, termed “idiopathic” endolymphatic hydrops (iEH). Although numerous precipitating/exacerbating factors have been proposed for MD, its etiology remains elusive. Here, using immunohistochemistry and in situ protein–protein interaction detection assays, we demonstrate mineralocorticoid-controlled sodium transport mechanisms in the epithelium of the extraosseous portion of the endolymphatic sac (eES) in the murine and human inner ears. Histological analysis of the eES in an extensive series of human temporal bones consistently revealed pathological changes in the eES in cases with iEH and a clinical history of MD, but no such changes were found in cases with “secondary” EH due to other otological diseases or in healthy controls. Notably, two etiologically different pathologies—degeneration and developmental hypoplasia—that selectively affect the eES in MD were distinguished. Clinical records from MD cases with degenerative and hypoplastic eES pathology revealed distinct intergroup differences in clinical disease presentation. Overall, we have identified for the first time two inner ear pathologies that are consistently present in MD and can be directly linked to the pathogenesis of EH, and which potentially affect the phenotypical presentation of MD. Electronic supplementary material The online version of this article (10.1007/s00401-018-1927-7) contains supplementary material, which is available to authorized users.

The ordered assembly of tau protein into abnormal filaments is a defining characteristic of Alzheimer’s disease (AD) and other neurodegenerative disorders. It is not known if the structures of tau filaments vary within, or between, the brains of individuals with AD. We used a combination of electron cryo-microscopy (cryo-EM) and immuno-gold negative-stain electron microscopy (immuno-EM) to determine the structures of paired helical filaments (PHFs) and straight filaments (SFs) from the frontal cortex of 17 cases of AD (15 sporadic and 2 inherited) and 2 cases of atypical AD (posterior cortical atrophy). The high-resolution structures of PHFs and SFs from the frontal cortex of 3 cases of AD, 2 sporadic and 1 inherited, were determined by cryo-EM. We also used immuno-EM to study the PHFs and SFs from a number of cortical and subcortical brain regions. PHFs outnumbered SFs in all AD cases. By cryo-EM, PHFs and SFs were made of two C-shaped protofilaments with a combined cross-β/β-helix structure, as described previously for one case of AD. The higher resolution structures obtained here showed two additional amino acids at each end of the protofilament. The immuno-EM findings, which indicated the presence of repeats 3 and 4, but not of the N-terminal regions of repeats 1 and 2, of tau in the filament cores of all AD cases, were consistent with the cryo-EM results. These findings show that there is no significant variation in tau filament structures between individuals with AD. This knowledge will be crucial for understanding the mechanisms that underlie tau filament formation and for developing novel diagnostics and therapies. Electronic supplementary material The online version of this article (10.1007/s00401-018-1914-z) contains supplementary material, which is available to authorized users.

ATENCIÓ: la correcció està també al DDD, cal relacionar??? https://ddd.uab.cat/record/226203 Altres ajuts: The following studies and consortia have contributed to this manuscript. Amsterdam dementia Cohort (ADC): Research of the Alzheimer center Amsterdam is part of the neurodegeneration research program of Amsterdam Neuroscience. The Alzheimer Center Amsterdam is supported by Stichting Alzheimer Nederland and Stichting VUmc fonds. The clinical database structure was developed with funding from Stichting Dioraphte. Genotyping of the Dutch case-control samples was performed in the context of EADB (European Alzheimer DNA biobank) funded by the JPco-fuND FP-829-029 (ZonMW projectnumber 733051061). 100-Plus study: We are grateful for the collaborative efforts of all participating centenarians and their family members and/or relations. This work was supported by Stichting Alzheimer Nederland (WE09.2014-03), Stichting Diorapthe, horstingstuit foundation, Memorabel (ZonMW projectnumber 733050814) and Stichting VUmc Fonds. Genotyping of the 100-Plus Study was performed in the context of EADB (European Alzheimer DNA biobank) funded by the JPco-fuND FP-829-029 (ZonMW projectnumber 733051061). German Study on Ageing, Cognition and Dementia in Primary Care Patients (AgeCoDe): This study/publication is part of the German Research Network on Dementia (KND), the German Research Network on Degenerative Dementia (KNDD; German Study on Ageing, Cognition and Dementia in Primary Care Patients; AgeCoDe), and the Health Service Research Initiative (Study on Needs, health service use, costs and health-related quality of life in a large sample of oldest-old primary care patients (85+; AgeQualiDe)) and was funded by the German Federal Ministry of Education and Research (grants KND: 01GI0102, 01GI0420, 01GI0422, 01GI0423, 01GI0429, 01GI0431, 01GI0433, 01GI0434; grants KNDD: 01GI0710, 01GI0711, 01GI0712, 01GI0713, 01GI0714, 01GI0715, 01GI0716; grants Health Service Research Initiative: 01GY1322A, 01GY1322B, 01GY1322C, 01GY1322D, 01GY1322E, 01GY1322F, 01GY1322G). Alfredo Ramirez was partly supported by the ADAPTED consortium: Alzheimer's disease Apolipoprotein Pathology for Treatment Elucidation and Development, which has received funding from the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement No 115975. Brain compendium: This work was funded by the UK Medical Research Council (13044). P.F.C. is a Wellcome Trust principal Fellow (212219/Z/18/Z) and a UK NIHR Senior Investigator, who receives support from the Medical Research Council Mitochondrial Biology Unit (MC_UU_00015/9), and the National Institute for Health Research (NIHR) Biomedical Research Centre based at Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, or the Department of Health.Clinical AD, Sweden: We would like to thank UCL Genomics for performing the genotyping analyses. Danish data: The studies behind the Danish long-lived cases received funding from The National Program for Research Infrastructure 2007 (grant no. 09-063256), the Danish Agency for Science Technology and Innovation, the Velux Foundation, the US National Institute of Health (P01 AG08761), the Danish Agency for Science, Technology and Innovation/The Danish Council for Independent Research (grant no. 11-107308), the European Union's Seventh Framework Programme (FP7/2007-2011) under grant agreement no. 259679, the INTERREG 4 A programme Syddanmark-Schleswig-K.E.R.N. (by EU funds from the European Regional Development Fund), the CERA Foundation (Lyon), the AXA Research Fund, Paris, and The Health Foundation (Helsefonden), Copenhagen, Denmark. The GOYA study was conducted as part of the activities of the Danish Obesity Research Centre (DanORC, www.danorc.dk) and The MRC centre for Causal Analyses in Translational Epidemiology (MRC CAiTE). The genotyping for GOYA was funded by the Wellcome Trust (WT 084762). GOYA is a nested study within The Danish National Birth Cohort which was established with major funding from the Danish National Research Foundation. Additional support for this cohort has been obtained from the Pharmacy Foundation, the Egmont Foundation, The March of Dimes Birth Defects Foundation, the Augustinus Foundation, and the Health Foundation. Fundació ACE (FACE): We would like to thank patients and controls who participated in this project. We are indebted to Trinitat Port-Carbó and her family for their support of Fundació ACE research programs. Fundació ACE collaborates with the Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED, Spain) and is one of the participating centers of the Dementia Genetics Spanish Consortium (DEGESCO). Agustín Ruiz has received support from the EU/EFPIA Innovative Medicines Initiative Joint Undertaking ADAPTED Grant No. 115975 and by grants PI13/02434 and PI16/01861. Acción Estratégica en Salud, integrated in the Spanish National R + D + I Plan and financed by ISCIII (Instituto de Salud Carlos III)-Subdirección General de Evaluación and the Fondo Europeo de Desarrollo Regional (FEDER- "Una manera de Hacer Europa"), by Fundación bancaria "La Caixa" and Grifols SA (GR@ACE project). Genetics of Healthy Ageing Study (GEHA - NL): The work described in this paper was funded mainly by the EU GEHA Project contract no. LSHM-CT-2004-503-270. Gothenburg Birth Cohort (GBC) Studies: We would like to thank UCL Genomics for performing the genotyping analyses. The studies were supported by The Stena Foundation, The Swedish Research Council (2015-02830, 2013-8717), The Swedish Research Council for Health, Working Life and Wellfare (2013-1202, 2005-0762, 2008-1210, 2013-2300, 2013-2496, 2013-0475), The Brain Foundation, Sahlgrenska University Hospital (ALF), The Alzheimer's Association (IIRG-03-6168), The Alzheimer's Association Zenith Award (ZEN-01-3151), Eivind och Elsa K:son Sylvans Stiftelse, The Swedish Alzheimer Foundation. International FTD-Genomics Consortium (IFGC): International FTD-Genomics Consortium (IFGC): The authors thank the IFGC for providing relevant data to support the analyses presented in this manuscript. Further acknowledgments for IFGC (https://ifgcsite.wordpress.com/), e.g. full members list and affiliations, are found in the online supplementary files. IPDGC (​The International Parkinson Disease Genomics Consortium): We also would like to thank all members of the International Parkinson Disease Genomics Consortium (IPDGC). See for a complete overview of members, acknowledgements and funding http://pdgenetics.org/partners. Kompetenznetz Multiple Sklerose (KKNMS): This work was supported by the German Ministry for Education and Research (BMBF) as part of the "German Competence Network Multiple Sclerosis" (KKNMS) (grant nos. 01GI0916 and 01GI0917) and the Munich Cluster for Systems Neurology (SyNergy). TA was supported by the BMBF through the Integrated Network IntegraMent, under the auspices of the e:Med Programme (01ZX1614J). BH was supported by the EU Horizon 2020 project MultipleMS.Longitudinal Aging Study Amsterdam (LASA) is largely supported by a grant from the Netherlands Ministry of Health, Welfare and Sports, Directorate of Long-Term Care. The authors are grateful to all LASA participants, the fieldwork team and all researchers for their ongoing commitment to the study. Leiden Longevity Study: This study was supported by a grant from the Innovation-Oriented Research Program on Genomics (SenterNovem IGE05007), the Centre for Medical Systems Biology, and the Netherlands Consortium for Healthy Ageing (Grant 050-060-810), all in the framework of the Netherlands Genomics Initiative/Netherlands Organization for Scientific Research (NWO) and by Unilever Colworth.Maria Carolina Dalmasso: Georg Forster Research Award (Alexander von Humboldt Foundation). Mayo Clinic AD, DLB, PD, PSP: We thank the patients and their families for their participation, without whom these studies would not have been possible. Funding for this work was supported by National Institute on Aging [RF AG051504 to NET.; U01 AG046139 to NET]; and National Institute of Neurological Disorders and Stroke [R01 NS080820 to NET; P50 NS072187]. The Mayo Clinic is a Lewy Body Dementia Association (LBDA) Research Center of Excellence, American Parkinson Disease Association (APDA) Information and Referral Center and Center for Advanced Research, NINDS Tau Center without Walls (U54-NS100693) and is supported by Mayo Clinic AD and related dementias genetics program, The Little Family Foundation, the Mangurian Foundation for Lewy body research and NINDS R01 NS078086 (to OAR). The PD program at the Mayo Clinic Florida is also supported by the Mayo Clinic Center for Regenerative Medicine, Mayo Clinic Center for Individualized Medicine, Mayo Clinic Neuroscience Focused Research Team (Cecilia and Dan Carmichael Family Foundation, and the James C. and Sarah K. Kennedy Fund for Neurodegenerative Disease Research at Mayo Clinic in Florida), the gift from Carl Edward Bolch, Jr., and Susan Bass Bolch, and The Sol Goldman Charitable Trust. Samples included in this study are from the brain bank at Mayo Clinic in Jacksonville which is supported by CurePSP The online version of this article (10.1007/s00401-019-02026-8) contains supplementary material, which is available to authorized users.

In Alzheimer’s disease (AD) and other tauopathies, the cytosolic protein Tau misfolds and forms intracellular aggregates which accumulate within the brain leading to neurodegeneration. Clinical progression is tightly linked to the progressive spread of Tau pathology throughout the brain, and several lines of evidence suggest that Tau aggregates or “seeds” may propagate pathology by spreading from cell to cell in a “prion like” manner. Accordingly, blocking the spread of extracellular seeds with an antibody could be a viable therapeutic approach. However, as the structure of Tau seeds is unknown, it is only possible to rationally design therapeutic Tau antibodies by making a priori assumptions. To avoid this, we developed a robust and quantitative cell based assay and employed an unbiased screening approach to identify the antibody with the highest activity against human Tau seeds. The selected antibody (D), directed to the mid-region of Tau (amino acids 235–250), potently blocked the seeding of human AD Tau and was also fully efficacious against seeds from progressive supranuclear palsy. When we compared this antibody with previously described reference antibodies, we were surprised to find that none of these antibodies showed comparable efficacy against human pathological seeds. Our data highlight the difficulty of predicting antibody accessible epitopes on pathological Tau seeds and question the potential efficacy of some of the Tau antibodies that are currently in clinical development. Electronic supplementary material The online version of this article (10.1007/s00401-018-1911-2) contains supplementary material, which is available to authorized users.

Women reportedly make up two-thirds of Alzheimer’s disease (AD) dementia sufferers. Many estimates regarding AD, however, are based on clinical series lacking autopsy confirmation. The Florida Autopsied Multi-Ethnic (FLAME) cohort was queried for AD cases with a total of 1625 identified ranging in age from 53 to 102 years at death. Standard neuropathologic procedures were employed and clinical information was retrospectively collected. Clinicopathologic and genetic data (MAPT and APOE) were stratified by sex. Within the neuropathologically diagnosed AD cohort, the overall number of women and men did not differ. Men were younger at onset of cognitive symptoms, had a shorter disease duration, and more often had atypical (non-amnestic) clinical presentations. The frequency of autopsy-confirmed AD among women and men stratified by age at death revealed an inverse U-shaped curve in men and a U-shaped curve in women, with both curves having inflections at approximately 70 years of age. Regional counts of neurofibrillary tangles differed in women and men, especially when examined by age intervals. Women had overall greater severity of neurofibrillary tangle counts compared to men, especially in the hippocampus. Men were more often classified as hippocampal sparing AD, whereas limbic predominant AD was more common in women. Men and women did not differ in frequency of MAPT haplotype or APOE genotype. Atypical clinical presentations, younger age at onset and shorter disease duration were more frequent in men, suggesting that the lower reported frequency of AD in men may be due to more frequent atypical clinical presentations not recognized as AD. Our data suggest that neuropathologically diagnosed AD cases have the same frequency of women and men, but their clinical presentations and ages at onset tend to differ. Electronic supplementary material The online version of this article (10.1007/s00401-018-1908-x) contains supplementary material, which is available to authorized users.

Autism has been linked with the changes in brain connectivity that disrupt neural communication, especially involving frontal networks. Pathological changes in white matter are evident in adults with autism, particularly affecting axons below the anterior cingulate cortices (ACC). It is still unknown whether axon pathology appears early or late in development and whether it changes or not from childhood through adulthood. To address these questions, we examined typical and pathological development of about 1 million axons in post-mortem brains of children, adolescents, and adults with and without autism (ages 3–67 years). We used high-resolution microscopy to systematically sample and study quantitatively the fine structure of myelinated axons in the white matter below ACC. We provide novel evidence of changes in the density, size and trajectories of ACC axons in typical postnatal development from childhood through adulthood. Against the normal profile of axon development, our data revealed lower density of myelinated axons that connect ACC with neighboring cortices in children with autism. In the course of development the proportion of thin axons, which form short-range pathways, increased significantly in individuals with autism, but remained flat in controls. In contrast, the relative proportion of thick axons, which form long-range pathways, increased from childhood to adulthood in the control group, but decreased in autism. Our findings provide a timeline for profound changes in axon density and thickness below ACC that affect axon physiology in a direction suggesting bias in short over distant neural communication in autism. Importantly, measures of axon density, myelination, and orientation provide white matter anisotropy/diffusivity estimates at the level of single axons. The structural template established can be used to compare with measures obtained from imaging in living subjects, and guide analysis of functional and structural imaging data from humans for comparison with pathological states. Electronic supplementary material The online version of this article (10.1007/s00401-018-1904-1) contains supplementary material, which is available to authorized users.

Progressive supranuclear palsy (PSP) is a neurodegenerative parkinsonian disorder characterized by tau pathology in neurons and glial cells. Transcriptional regulation has been implicated as a potential mechanism in conferring disease risk and neuropathology for some PSP genetic risk variants. However, the role of transcriptional changes as potential drivers of distinct cell-specific tau lesions has not been explored. In this study, we integrated brain gene expression measurements, quantitative neuropathology traits and genome-wide genotypes from 268 autopsy-confirmed PSP patients to identify transcriptional associations with unique cell-specific tau pathologies. We provide individual transcript and transcriptional network associations for quantitative oligodendroglial (coiled bodies = CB), neuronal (neurofibrillary tangles = NFT), astrocytic (tufted astrocytes = TA) tau pathology, and tau threads and genomic annotations of these findings. We identified divergent patterns of transcriptional associations for the distinct tau lesions, with the neuronal and astrocytic neuropathologies being the most different. We determined that NFT are positively associated with a brain co-expression network enriched for synaptic and PSP candidate risk genes, whereas TA are positively associated with a microglial gene-enriched immune network. In contrast, TA is negatively associated with synaptic and NFT with immune system transcripts. Our findings have implications for the diverse molecular mechanisms that underlie cell-specific vulnerability and disease risk in PSP. Electronic supplementary material The online version of this article (10.1007/s00401-018-1900-5) contains supplementary material, which is available to authorized users.

The deposition of the amyloid β-protein (Aβ) in senile plaques is one of the histopathological hallmarks of Alzheimer’s disease (AD). Aβ-plaques arise first in neocortical areas and, then, expand into further brain regions in a process described by 5 phases. Since it is possible to identify amyloid pathology with radioactive-labeled tracers by positron emission tomography (PET) the question arises whether it is possible to distinguish the neuropathological Aβ-phases with amyloid PET imaging. To address this question we reassessed 97 cases of the end-of-life study cohort of the phase 3 [18F]flutemetamol trial (ClinicalTrials.gov identifiers NCT01165554, and NCT02090855) by combining the standardized uptake value ratios (SUVRs) with pons as reference region for cortical and caudate nucleus-related [18F]flutemetamol-retention. We tested them for their prediction of the neuropathological pattern found at autopsy. By defining threshold levels for cortical and caudate nucleus SUVRs we could distinguish different levels of [18F]flutemetamol uptake termed PET-Aβ phase estimates. When comparing these PET-Aβ phase estimates with the neuropathological Aβ-phases we found that PET-Aβ phase estimate 0 corresponded with Aβ-phases 0-2, 1 with Aβ-phase 3, 2 with Aβ-phase 4, and 3 with Aβ-phase 5. Classification using the PET-Aβ phase estimates predicted the correct Aβ-phase in 72.16% of the cases studied here. Bootstrap analysis was used to confirm the robustness of the estimates around this association. When allowing a range of ± 1 phase for a given Aβ-phase correct classification was given in 96.91% of the cases. In doing so, we provide a novel method to convert SUVR-levels into PET-Aβ phase estimates that can be easily translated into neuropathological phases of Aβ-deposition. This method allows direct conclusions about the pathological distribution of amyloid plaques (Aβ-phases) in vivo. Accordingly, this method may be ideally suited to detect early preclinical AD-patients, to follow them with disease progression, and to provide a more precise prognosis for them based on the knowledge about the underlying pathological phase of the disease. Electronic supplementary material The online version of this article (10.1007/s00401-018-1897-9) contains supplementary material, which is available to authorized users.

Recently, we described a machine learning approach for classification of central nervous system tumors based on the analysis of genome-wide DNA methylation patterns [6]. Here, we report on DNA methylation-based central nervous system (CNS) tumor diagnostics conducted in our institution between the years 2015 and 2018. In this period, more than 1000 tumors from the neurosurgical departments in Heidelberg and Mannheim and more than 1000 tumors referred from external institutions were subjected to DNA methylation analysis for diagnostic purposes. We describe our current approach to the integrated diagnosis of CNS tumors with a focus on constellations with conflicts between morphological and molecular genetic findings. We further describe the benefit of integrating DNA copy-number alterations into diagnostic considerations and provide a catalog of copy-number changes for individual DNA methylation classes. We also point to several pitfalls accompanying the diagnostic implementation of DNA methylation profiling and give practical suggestions for recurring diagnostic scenarios. Electronic supplementary material The online version of this article (10.1007/s00401-018-1879-y) contains supplementary material, which is available to authorized users.

Transactivating DNA-binding protein-43 (TDP-43) deposits represent a typical finding in almost all ALS patients, more than half of FTLD patients and patients with several other neurodegenerative disorders. It appears that perturbation of nucleo-cytoplasmic transport is an important event in these conditions but the mechanistic role and the fate of TDP-43 during neuronal degeneration remain elusive. We have developed an experimental system for visualising the perturbed nucleocytoplasmic transport of neuronal TDP-43 at the single-cell level in vivo using zebrafish spinal cord. This approach enabled us to image TDP-43-expressing motor neurons before and after experimental initiation of cell death. We report the formation of mobile TDP-43 deposits within degenerating motor neurons, which are normally phagocytosed by microglia. However, when microglial cells were depleted, injury-induced motor neuron degeneration follows a characteristic process that includes TDP-43 redistribution into the cytoplasm, axon and extracellular space. This is the first demonstration of perturbed TDP-43 nucleocytoplasmic transport in vivo, and suggests that impairment in microglial phagocytosis of dying neurons may contribute towards the formation of pathological TDP-43 presentations in ALS and FTLD. Electronic supplementary material The online version of this article (10.1007/s00401-018-1875-2) contains supplementary material, which is available to authorized users.

The peripheral immune system plays a critical role in aging and in the response to brain injury. Emerging data suggest inflammatory responses are exacerbated in older animals following ischemic stroke; however, our understanding of these age-related changes is poor. In this work, we demonstrate marked differences in the composition of circulating and infiltrating leukocytes recruited to the ischemic brain of old male mice after stroke compared to young male mice. Blood neutrophilia and neutrophil invasion into the brain were increased in aged animals. Relative to infiltrating monocyte populations, brain-invading neutrophils had reduced phagocytic potential, and produced higher levels of reactive oxygen species and extracellular matrix-degrading enzymes (i.e., MMP-9), which were further exacerbated with age. Hemorrhagic transformation was more pronounced in aged versus young mice relative to infarct size. High numbers of myeloperoxidase-positive neutrophils were found in postmortem human brain samples of old (> 71 years) acute ischemic stroke subjects compared to non-ischemic controls. Many of these neutrophils were found in the brain parenchyma. A large proportion of these neutrophils expressed MMP-9 and positively correlated with hemorrhage and hyperemia. MMP-9 expression and hemorrhagic transformation after stroke increased with age. These changes in the myeloid response to stroke with age led us to hypothesize that the bone marrow response to stroke is altered with age, which could be important for the development of effective therapies targeting the immune response. We generated heterochronic bone marrow chimeras as a tool to determine the contribution of peripheral immune senescence to age- and stroke-induced inflammation. Old hosts that received young bone marrow (i.e., Young → Old) had attenuation of age-related reductions in bFGF and VEGF and showed improved locomotor activity and gait dynamics compared to isochronic (Old → Old) controls. Microglia in young heterochronic mice (Old → Young) developed a senescent-like phenotype. After stroke, aged animals reconstituted with young marrow had reduced behavioral deficits compared to isochronic controls, and had significantly fewer brain-infiltrating neutrophils. Increased rates of hemorrhagic transformation were seen in young mice reconstituted with aged bone marrow. This work suggests that age alters the immunological response to stroke, and that this can be reversed by manipulation of the peripheral immune cells in the bone marrow. Electronic supplementary material The online version of this article (10.1007/s00401-018-1859-2) contains supplementary material, which is available to authorized users.

Alzheimer’s disease (AD) is characterized by accumulation of tau neurofibrillary tangles (NFTs) and, according to the prion model, transcellular propagation of pathological “seeds” may underlie its progression. Staging of NFT pathology with phospho-tau antibody is useful to classify AD and primary age-related tauopathy (PART) cases. The locus coeruleus (LC) shows the earliest phospho-tau signal, whereas other studies suggest that pathology begins in the transentorhinal/entorhinal cortices (TRE/EC). The relationship of tau seeding activity, phospho-tau pathology, and progression of neurodegeneration remains obscure. Consequently, we employed an established cellular biosensor assay to quantify tau seeding activity in fixed human tissue, in parallel with AT8 phospho-tau staining of immediately adjacent sections. We studied four brain regions from each of n = 247 individuals across a range of disease stages. We detected the earliest and most robust seeding activity in the TRE/EC. The LC did not uniformly exhibit seeding activity until later NFT stages. We also detected seeding activity in the superior temporal gyrus (STG) and primary visual cortex (VC) at stages before NFTs and/or AT8-immunopositivity were detectable. AD and putative PART cases exhibited similar patterns of seeding activity that anticipated histopathology across all NFT stages. Our findings are consistent with the prion model and suggest that pathological seeding activity begins in the TRE/EC rather than in the LC. In the analysis of tauopathy, quantification of seeding activity may offer an important addition to classical histopathology. Electronic supplementary material The online version of this article (10.1007/s00401-018-1855-6) contains supplementary material, which is available to authorized users.

Neurogranin (Ng) is a post-synaptic protein that previously has been shown to be a biomarker for synaptic function when measured in cerebrospinal fluid (CSF). The CSF concentration of Ng is increased in Alzheimer’s disease dementia (ADD), and even in the pre-dementia stage. In this prospective study, we used an enzyme-linked immunosorbent assay that quantifies Ng in CSF to test the performance of Ng as a marker of synaptic function. In 915 patients, CSF Ng was evaluated across several different neurodegenerative diseases. Of these 915 patients, 116 had a neuropathologically confirmed definitive diagnosis and the relation between CSF Ng and topographical distribution of different pathologies in the brain was evaluated. CSF Ng was specifically increased in ADD compared to eight other neurodegenerative diseases, including Parkinson’s disease (p

Bone marrow-derived cells are known to infiltrate the adult brain and fuse with cerebellar Purkinje cells. Histological observations that such heterotypic cell fusion events are substantially more frequent following cerebellar injury suggest they could have a role in the protection of mature brain neurons. To date, the possibility that cell fusion can preserve or restore the structure and function of adult brain neurons has not been directly addressed; indeed, though frequently suggested, the possibility of benefit has always been rather speculative. Here we report, for the first time, that fusion of a bone marrow-derived cell with a neuron in vivo, in the mature brain, results in the formation of a spontaneously firing neuron. Notably, we also provide evidence supporting the concept that heterotypic cell fusion acts as a biological mechanism to repair pathological changes in Purkinje cell structure and electrophysiology. We induced chronic central nervous system inflammation in chimeric mice expressing bone marrow cells tagged with enhanced green fluorescent protein. Subsequent in-depth histological analysis revealed significant Purkinje cell injury. In addition, there was an increased incidence of cell fusion between bone marrow-derived cells and Purkinje cells, revealed as enhanced green fluorescent protein-expressing binucleate heterokaryons. These fused cells resembled healthy Purkinje cells in their morphology, soma size, ability to synthesize the neurotransmitter gamma-aminobutyric acid, and synaptic innervation from neighbouring cells. Extracellular recording of spontaneous firing ex vivo revealed a shift in the predominant mode of firing of non-fused Purkinje cells in the context of cerebellar inflammation. By contrast, the firing patterns of fused Purkinje cells were the same as in healthy control cerebellum, indicating that fusion of bone marrow-derived cells with Purkinje cells mitigated the effects of cell injury on electrical activity. Together, our histological and electrophysiological results provide novel fundamental insights into physiological processes by which nerve cells are protected in adult life. Electronic supplementary material The online version of this article (10.1007/s00401-018-1833-z) contains supplementary material, which is available to authorized users.

Amyloid-β (Aβ) is a peptide deposited in the brain parenchyma in Alzheimer’s disease and in cerebral blood vessels, causing cerebral amyloid angiopathy (CAA). Aβ pathology is transmissible experimentally in animals and through medical procedures in humans, such as contaminated growth hormone or dura mater transplantation in the context of iatrogenic prion disease. Here, we present four patients who underwent neurosurgical procedures during childhood or teenage years and presented with intracerebral haemorrhage approximately three decades later, caused by severe CAA. None of these patients carried pathogenic mutations associated with early Aβ pathology development. In addition, we identified in the literature four patients with a history of neurosurgical intervention and subsequent development of CAA. These findings raise the possibility that Aβ pathology may be transmissible, as prion disease is, through neurosurgical procedures. Electronic supplementary material The online version of this article (10.1007/s00401-018-1822-2) contains supplementary material, which is available to authorized users.

A GGGGCC hexanucleotide repeat expansion in the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. Neurodegeneration may occur via transcription of the repeats into inherently toxic repetitive sense and antisense RNA species, or via repeat-associated non-ATG initiated translation (RANT) of sense and antisense RNA into toxic dipeptide repeat proteins. We have previously demonstrated that regular interspersion of repeat RNA with stop codons prevents RANT (RNA-only models), allowing us to study the role of repeat RNA in isolation. Here we have created novel RNA-only Drosophila models, including the first models of antisense repeat toxicity, and flies expressing extremely large repeats, within the range observed in patients. We generated flies expressing ~ 100 repeat sense or antisense RNA either as part of a processed polyadenylated transcript or intronic sequence. We additionally created Drosophila expressing > 1000 RNA-only repeats in the sense direction. When expressed in adult Drosophila neurons polyadenylated repeat RNA is largely cytoplasmic in localisation, whilst intronic repeat RNA forms intranuclear RNA foci, as does > 1000 repeat RNA, thus allowing us to investigate both nuclear and cytoplasmic RNA toxicity. We confirmed that these RNA foci are capable of sequestering endogenous Drosophila RNA-binding proteins, and that the production of dipeptide proteins (poly-glycine–proline, and poly-glycine–arginine) is suppressed in our models. We find that neither cytoplasmic nor nuclear sense or antisense RNA are toxic when expressed in adult Drosophila neurons, suggesting they have a limited role in disease pathogenesis. Electronic supplementary material The online version of this article (10.1007/s00401-017-1798-3) contains supplementary material, which is available to authorized users.

BACE1 is the rate-limiting protease in the production of synaptotoxic β-amyloid (Aβ) species and hence one of the prime drug targets for potential therapy of Alzheimer’s disease (AD). However, so far pharmacological BACE1 inhibition failed to rescue the cognitive decline in mild-to-moderate AD patients, which indicates that treatment at the symptomatic stage might be too late. In the current study, chronic in vivo two-photon microscopy was performed in a transgenic AD model to monitor the impact of pharmacological BACE1 inhibition on early β-amyloid pathology. The longitudinal approach allowed to assess the kinetics of individual plaques and associated presynaptic pathology, before and throughout treatment. BACE1 inhibition could not halt but slow down progressive β-amyloid deposition and associated synaptic pathology. Notably, the data revealed that the initial process of plaque formation, rather than the subsequent phase of gradual plaque growth, is most sensitive to BACE1 inhibition. This finding of particular susceptibility of plaque formation has profound implications to achieve optimal therapeutic efficacy for the prospective treatment of AD. Electronic supplementary material The online version of this article (10.1007/s00401-017-1804-9) contains supplementary material, which is available to authorized users.

Tumours can be viewed as aberrant tissues or organs sustained by tumorigenic stem-like cells that engage into dysregulated histo/organogenetic processes. Paragangliomas, prototypical organoid tumours constituted by dysmorphic variants of the vascular and neural tissues found in normal paraganglia, provide a model to test this hypothesis. To understand the origin of paragangliomas, we built a biobank comprising 77 cases, 18 primary cultures, 4 derived cell lines, 80 patient-derived xenografts and 11 cell-derived xenografts. We comparatively investigated these unique complementary materials using morphofunctional, ultrastructural and flow cytometric assays accompanied by microRNA studies. We found that paragangliomas contain stem-like cells with hybrid mesenchymal/vasculoneural phenotype, stabilized and expanded in the derived cultures. The viability and growth of such cultures depended on the downregulation of the miR-200 and miR-34 families, which allowed high PDGFRA and ZEB1 protein expression levels. Both tumour tissue- and cell culture-derived xenografts recapitulated the vasculoneural paraganglioma structure and arose from mesenchymal-like cells through a fixed developmental sequence. First, vasculoangiogenesis organized the microenvironment, building a perivascular niche which in turn supported neurogenesis. Neuroepithelial differentiation was associated with severe mitochondrial dysfunction, not present in cultured paraganglioma cells, but acquired in vivo during xenograft formation. Vasculogenesis was the Achilles’ heel of xenograft development. In fact, imatinib, that targets endothelial-mural signalling, blocked paraganglioma xenograft formation (11 xenografts from 12 cell transplants in the control group versus 2 out of 10 in the treated group, P = 0.0015). Overall our key results were unaffected by the SDHx gene carrier status of the patient, characterized for 70 out of 77 cases. In conclusion, we explain the biphasic vasculoneural structure of paragangliomas and identify an early and pharmacologically actionable phase of paraganglioma organization. Electronic supplementary material The online version of this article (10.1007/s00401-017-1799-2) contains supplementary material, which is available to authorized users.

The complement system is implicated in synapse loss in the MS hippocampus, but the functional consequences of synapse loss remain poorly understood. Here, in post-mortem MS hippocampi with demyelination we find that deposits of the complement component C1q are enriched in the CA2 subfield, are linked to loss of inhibitory synapses and are significantly higher in MS patients with cognitive impairments compared to those with preserved cognitive functions. Using the cuprizone mouse model of demyelination, we corroborated that C1q deposits are highest within the demyelinated dorsal hippocampal CA2 pyramidal layer and co-localized with inhibitory synapses engulfed by microglia/macrophages. In agreement with the loss of inhibitory perisomatic synapses, we found that Schaffer collateral feedforward inhibition but not excitation was impaired in CA2 pyramidal neurons and accompanied by intrinsic changes and a reduced spike output. Finally, consistent with excitability deficits, we show that cuprizone-treated mice exhibit impaired encoding of social memories. Together, our findings identify CA2 as a critical circuit in demyelinated intrahippocampal lesions and memory dysfunctions in MS. Supplementary Information The online version contains supplementary material available at 10.1007/s00401-021-02338-8.

Parkinson’s disease is characterized by degeneration of substantia nigra dopamine neurons and by intraneuronal aggregates, primarily composed of misfolded α-synuclein. The α-synuclein aggregates in Parkinson’s patients are suggested to first appear in the olfactory bulb and enteric nerves and then propagate, following a stereotypic pattern, via neural pathways to numerous regions across the brain. We recently demonstrated that after injection of either mouse or human α-synuclein fibrils into the olfactory bulb of wild-type mice, α-synuclein fibrils recruited endogenous α-synuclein into pathological aggregates that spread transneuronally to over 40 other brain regions and subregions, over 12 months. We previously reported the progressive spreading of α-synuclein aggregates, between 1 and 12 months following α-synuclein fibril injections, and now report how far the pathology has spread 18- and 23-month post-injection in this model. Our data show that between 12 and 18 months, there is a further increase in the number of brain regions exhibiting pathology after human, and to a lesser extent mouse, α-synuclein fibril injections. At both 18 and 23 months after injection of mouse and human α-synuclein fibrils, we observed a reduction in the density of α-synuclein aggregates in some brain regions compared to others at 12 months. At 23 months, no additional brain regions exhibited α-synuclein aggregates compared to earlier time points. In addition, we also demonstrate that the induced α-synucleinopathy triggered a significant early neuron loss in the anterior olfactory nucleus. By contrast, there was no loss of mitral neurons in the olfactory bulb, even at 18 month post-injection. We speculate that the lack of continued progression of α-synuclein pathology is due to compromise of the neural circuitry, consequential to neuron loss and possibly to the activation of proteolytic mechanisms in resilient neurons of wild-type mice that counterbalances the spread and seeding by degrading pathogenic α-synuclein. Electronic supplementary material The online version of this article (10.1007/s00401-017-1792-9) contains supplementary material, which is available to authorized users.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease with no effective treatments. Numerous RNA-binding proteins (RBPs) have been shown to be altered in ALS, with mutations in 11 RBPs causing familial forms of the disease, and 6 more RBPs showing abnormal expression/distribution in ALS albeit without any known mutations. RBP dysregulation is widely accepted as a contributing factor in ALS pathobiology. There are at least 1542 RBPs in the human genome; therefore, other unidentified RBPs may also be linked to the pathogenesis of ALS. We used IBM Watson® to sieve through all RBPs in the genome and identify new RBPs linked to ALS (ALS-RBPs). IBM Watson extracted features from published literature to create semantic similarities and identify new connections between entities of interest. IBM Watson analyzed all published abstracts of previously known ALS-RBPs, and applied that text-based knowledge to all RBPs in the genome, ranking them by semantic similarity to the known set. We then validated the Watson top-ten-ranked RBPs at the protein and RNA levels in tissues from ALS and non-neurological disease controls, as well as in patient-derived induced pluripotent stem cells. 5 RBPs previously unlinked to ALS, hnRNPU, Syncrip, RBMS3, Caprin-1 and NUPL2, showed significant alterations in ALS compared to controls. Overall, we successfully used IBM Watson to help identify additional RBPs altered in ALS, highlighting the use of artificial intelligence tools to accelerate scientific discovery in ALS and possibly other complex neurological disorders. Electronic supplementary material The online version of this article (10.1007/s00401-017-1785-8) contains supplementary material, which is available to authorized users.

N-Acetylaspartate (NAA) is the second most abundant organic metabolite in the brain, but its physiological significance remains enigmatic. Toxic NAA accumulation appears to be the key factor for neurological decline in Canavan disease—a fatal neurometabolic disorder caused by deficiency in the NAA-degrading enzyme aspartoacylase. To date clinical outcome of gene replacement therapy for this spongiform leukodystrophy has not met expectations. To identify the target tissue and cells for maximum anticipated treatment benefit, we employed comprehensive phenotyping of novel mouse models to assess cell type-specific consequences of NAA depletion or elevation. We show that NAA-deficiency causes neurological deficits affecting unconscious defensive reactions aimed at protecting the body from external threat. This finding suggests, while NAA reduction is pivotal to treat Canavan disease, abrogating NAA synthesis should be avoided. At the other end of the spectrum, while predicting pathological severity in Canavan disease mice, increased brain NAA levels are not neurotoxic per se. In fact, in transgenic mice overexpressing the NAA synthesising enzyme Nat8l in neurons, supra-physiological NAA levels were uncoupled from neurological deficits. In contrast, elimination of aspartoacylase expression exclusively in oligodendrocytes elicited Canavan disease like pathology. Although conditional aspartoacylase deletion in oligodendrocytes abolished expression in the entire CNS, the remaining aspartoacylase in peripheral organs was sufficient to lower NAA levels, delay disease onset and ameliorate histopathology. However, comparable endpoints of the conditional and complete aspartoacylase knockout indicate that optimal Canavan disease gene replacement therapies should restore aspartoacylase expression in oligodendrocytes. On the basis of these findings we executed an ASPA gene replacement therapy targeting oligodendrocytes in Canavan disease mice resulting in reversal of pre-existing CNS pathology and lasting neurological benefits. This finding signifies the first successful post-symptomatic treatment of a white matter disorder using an adeno-associated virus vector tailored towards oligodendroglial-restricted transgene expression. Electronic supplementary material The online version of this article (10.1007/s00401-017-1784-9) contains supplementary material, which is available to authorized users.

Recent studies have demonstrated that tumor-driving alterations are often different among gliomas that originated from different brain regions and have underscored the importance of analyzing molecular characteristics of gliomas stratified by brain region. Therefore, to elucidate molecular characteristics of diffuse cerebellar gliomas (DCGs), 27 adult, mostly glioblastoma cases were analyzed. Comprehensive analysis using whole-exome sequencing, RNA sequencing, and Infinium methylation array (n = 17) demonstrated their distinct molecular profile compared to gliomas in other brain regions. Frequent mutations in chromatin-modifier genes were identified including, noticeably, a truncating mutation in SETD2 (n = 4), which resulted in loss of H3K36 trimethylation and was mutually exclusive with H3F3A K27M mutation (n = 3), suggesting that epigenetic dysregulation may lead to DCG tumorigenesis. Alterations that cause loss of p53 function including TP53 mutation (n = 9), PPM1D mutation (n = 2), and a novel type of PPM1D fusion (n = 1), were also frequent. On the other hand, mutations and copy number changes commonly observed in cerebral gliomas were infrequent. DNA methylation profile analysis demonstrated that all DCGs except for those with H3F3A mutations were categorized in the “RTK I (PDGFRA)” group, and those DCGs had a gene expression signature that was highly associated with PDGFRA. Furthermore, compared with the data of 315 gliomas derived from different brain regions, promoter methylation of transcription factors genes associated with glial development showed a characteristic pattern presumably reflecting their tumor origin. Notably, SOX10, a key transcription factor associated with oligodendroglial differentiation and PDGFRA regulation, was up-regulated in both DCG and H3 K27M-mutant diffuse midline glioma, suggesting their developmental and biological commonality. In contrast, SOX10 was silenced by promoter methylation in most cerebral gliomas. These findings may suggest potential tailored targeted therapy for gliomas according to their brain region, in addition to providing molecular clues to identify the region-related cellular origin of DCGs. Electronic supplementary material The online version of this article (doi:10.1007/s00401-017-1771-1) contains supplementary material, which is available to authorized users.

A growing body of evidence suggests that a loss of chromosome 9 open reading frame 72 (C9ORF72) expression, formation of dipeptide-repeat proteins, and generation of RNA foci contribute to disease pathogenesis in amyotrophic lateral sclerosis and frontotemporal dementia. Although the levels of C9ORF72 transcripts and dipeptide-repeat proteins have already been examined thoroughly, much remains unknown about the role of RNA foci in C9ORF72-linked diseases. As such, we performed a comprehensive RNA foci study in an extensive pathological cohort of C9ORF72 expansion carriers (n = 63). We evaluated two brain regions using a newly developed computer-automated pipeline allowing recognition of cell nuclei and RNA foci (sense and antisense) supplemented by manual counting. In the frontal cortex, the percentage of cells with sense or antisense RNA foci was 26 or 12%, respectively. In the cerebellum, 23% of granule cells contained sense RNA foci and 1% antisense RNA foci. Interestingly, the highest percentage of cells with RNA foci was observed in cerebellar Purkinje cells (~70%). In general, more cells contained sense RNA foci than antisense RNA foci; however, when antisense RNA foci were present, they were usually more abundant. We also observed that an increase in the percentage of cells with antisense RNA foci was associated with a delayed age at onset in the frontal cortex (r = 0.43, p = 0.003), whereas no other associations with clinico-pathological features were seen. Importantly, our large-scale study is the first to provide conclusive evidence that RNA foci are not the determining factor of the clinico-pathological variability observed in C9ORF72 expansion carriers and it emphasizes that the distribution of RNA foci does not follow the pattern of neurodegeneration, stressing the complex interplay between different aspects of C9ORF72-related diseases. Electronic supplementary material The online version of this article (doi:10.1007/s00401-017-1725-7) contains supplementary material, which is available to authorized users.

The research was supported by the Alzheimer’s Society (Grant Number: AS-PG-2013-011). Tissue for this study was provided by the Newcastle Brain Tissue Resource, which is funded in part by a grant from the UK Medical Research Council (G0400074) and by Brains for Dementia research, a joint venture between Alzheimer’s Society and Alzheimer’s Research UK. Cerebral white matter lesions (WML) encompass axonal loss and demyelination, and the pathogenesis is assumed to be small vessel disease (SVD)-related ischemia. However, WML may also result from the activation of Wallerian degeneration as a consequence of cortical Alzheimer’s disease (AD) pathology, i.e. hyperphosphorylated tau (HPτ) and amyloid-beta (Aβ) deposition. WML seen in AD have a posterior predominance compared to non-demented individuals but it is unclear whether the pathological and molecular signatures of WML differ between these two groups. We investigated differences in the composition and aetiology of parietal WML from AD and non-demented controls. Parietal WML tissue from 55 human post-mortem brains (AD, n = 27; non-demented controls, n = 28) were quantitatively assessed for axonal loss and demyelination, as well as for cortical HPτ and Aβ burden and SVD. Biochemical assessment included Wallerian degeneration protease calpain and the myelin-associated glycoprotein (MAG) to proteolipid protein (PLP) ratio (MAG:PLP) as a measure of hypoperfusion. WML severity was associated with both axonal loss and demyelination in AD, but only with demyelination in controls. Calpain was significantly increased in WML tissue in AD, whereas MAG:PLP was significantly reduced in controls. Calpain levels were associated with increasing amounts of cortical AD-pathology but not SVD. We conclude that parietal WML seen in AD differ in their pathological composition and aetiology compared to WML seen in aged controls: WML seen in AD may be associated with Wallerian degeneration that is triggered by cortical AD-pathology, whereas WML in aged controls are due to ischaemia. Hence, parietal WML as seen on MRI should not invariably be interpreted as a surrogate biomarker for SVD as they may be indicative of cortical AD-pathology, and therefore, AD should also be considered as the main underlying cause for cognitive impairment in cases with parietal WML. Publisher PDF