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BACKGROUND: Alzheimer's disease (AD) patients display alterations in cerebrospinal fluid (CSF) and plasma sphingolipids. The APOE4 genotype increases the risk of developing AD.OBJECTIVE: To test the hypothesis that the APOE4 genotype affects common sphingolipids in CSF and in plasma of patients with early stages of AD.METHODS: Patients homozygous for APOE4 and non-APOE4 carriers with mild cognitive impairment (MCI; n = 20 versus 20) were compared to patients with subjective cognitive decline (SCD; n = 18 versus 20). Sphingolipids in CSF and plasma lipoproteins were determined by liquid-chromatography-tandem mass spectrometry. Aβ42 levels in CSF were determined by immunoassay.RESULTS: APOE4 homozygotes displayed lower levels of sphingomyelin (SM; p = 0.042), SM(d18:1/18:0) (p = 0.026), and Aβ42 (p 0.49; p CONCLUSION: The APOE4 genotype affects sphingolipid profiles of CSF and plasma lipoproteins already at early stages of AD. ApoE4 may contribute to the early development of AD through modulation of sphingolipid metabolism.

ObjectiveTo assess the [18F]flortaucipir binding distribution across MAPT mutations in presymptomatic and symptomatic carriers.MethodsWe compared regional [18F]flortaucipir binding potential (BPND) derived from a 130-minute dynamic [18F]flortaucipir PET scan in 9 (pre)symptomatic MAPT mutation carriers (4 with P301L [1 symptomatic], 2 with R406W [1 symptomatic], 1 presymptomatic L315R, 1 presymptomatic S320F, and 1 symptomatic G272V carrier) with 30 cognitively normal controls and 52 patients with Alzheimer disease.Results[18F]Flortaucipir BPND images showed overall highest binding in the symptomatic carriers. This was most pronounced in the symptomatic R406W carrier in whom tau binding exceeded the normal control range in the anterior cingulate cortex, insula, amygdala, temporal, parietal, and frontal lobe. Elevated medial temporal lobe BPND was observed in a presymptomatic R406W carrier. The single symptomatic carrier and 1 of the 3 presymptomatic P301L carriers showed elevated [18F]flortaucipir BPND in the insula, parietal, and frontal lobe compared to controls. The symptomatic G272V carrier exhibited a widespread elevated cortical BPND, with at neuropathologic examination a combination of 3R pathology and encephalitis. The L315R presymptomatic mutation carrier showed higher frontal BPND compared to controls. The BPND values of the S320F presymptomatic mutation carrier fell within the range of controls.ConclusionPresymptomatic MAPT mutation carriers already showed subtle elevated tau binding, whereas symptomatic MAPT mutation carriers showed a more marked increase in [18F]flortaucipir BPND. Tau deposition was most pronounced in R406W MAPT (pre)symptomatic mutation carriers, which is associated with both 3R and 4R tau accumulation. Thus, [18F]flortaucipir may serve as an early biomarker for MAPT mutation carriers in mutations that cause 3R/4R tauopathies.

Background Axons, crucial for impulse transmission and cellular trafficking, are thought to be primary targets of neurodegeneration in Parkinson’s disease (PD) and Dementia with Lewy bodies (DLB). Axonal degeneration occurs early, preceeding and exceeding neuronal loss, and contributes to the spread of pathology, yet is poorly described outside the nigrostriatal circuitry. The insula, a cortical brain hub, was recently discovered as highly vulnerable to pathology and plays a role in cognitive deficits in PD and DLB. The aim of this study was to evaluate morphological features and burden of proteinopathy and axonal degeneration in the anterior insular sub-regions in PD, PD with dementia (PDD), and DLB. Methods α-Synuclein (α-syn), phosphorylated (p-)tau, and amyloid-β pathology load were evaluated in the anterior insula (agranular and dysgranular) subregions of brain donors (n = 27). Axonal loss was evaluated using modified Bielschowsky silver staining and quantified using stereology. Cytoskeletal damage was comprehensively studied using immunofluorescent multi-labelling and 3D confocal laser-scanning microscopy. Results Compared to PD(D), DLB showed significantly higher α-syn and p-tau pathology load, argyrophilic grains, and most severe axonal loss, particularly in the anterior agranular insula. Alternatively, the dysgranular insula showed a significant higher load of amyloid-β pathology. Using mixed model analysis, p-tau contributed most to axonal loss in the DLB group, highest in the anterior agranular insula. Neurofilament and myelin showed degenerative changes including swellings, demyelination, and detachment of the axon-myelin unit. Conclusions Our results highlight the selective vulnerability of the anterior agranular insular sub-region to various converging pathologies, leading to impaired axonal integrity in PD(D) and DLB, disrupting its functional properties and potentially contributing to cognitive, emotional, and autonomic deficits.

Objective Accumulation of amyloid‐β is among the earliest changes in Alzheimer’s disease (AD). Amyloid‐β positron emission tomography (PET) and Aβ 42 in cerebrospinal fluid (CSF) both assess amyloid‐β pathology in‐vivo, but 10–20% of cases show discordant (CSF+/PET− or CSF‐/PET+) results. The neuropathological correspondence with amyloid‐β CSF/PET discordance is unknown. Methods We included 21 patients from our tertiary memory clinic who had undergone both CSF Aβ 42 analysis and amyloid‐β PET, and had neuropathological data available. Amyloid‐β PET and CSF results were compared with neuropathological ABC scores (comprising of Thal (A), Braak (B), and CERAD (C) stage, all ranging from 0 [low] to 3 [high]) and neuropathological diagnosis. Results Neuropathological diagnosis was AD in 11 (52%) patients. Amyloid‐β PET was positive in all A3, C2, and C3 cases and in one of the two A2 cases. CSF Aβ 42 was positive in 92% of ≥A2 and 90% of ≥C2 cases. PET and CSF were discordant in three of 21 (14%) cases: CSF+/PET− in a patient with granulomatosis with polyangiitis (A0B0C0), CSF+/PET− in a patient with FTLD‐TDP type B (A2B1C1), and CSF‐/PET+ in a patient with AD (A3B3C3). Two CSF+/PET+ cases had a non‐AD neuropathological diagnosis, that is FTLD‐TDP type E (A3B1C1) and adult‐onset leukoencephalopathy with axonal spheroids (A1B1C0). Interpretation Our study demonstrates neuropathological underpinnings of amyloid‐β CSF/PET discordance. Furthermore, amyloid‐β biomarker positivity on both PET and CSF did not invariably result in an AD diagnosis at autopsy, illustrating the importance of considering relevant comorbidities when evaluating amyloid‐β biomarker results.

Background: Rare variants in the low-density lipoprotein receptor related protein 10 gene (LRP10) have recently been implicated in the etiology of Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). Objective: We searched for LRP10 variants in a new series of brain donors with dementia and Lewy pathology (LP) at autopsy, or dementia and parkinsonism without LP but with various other neurodegenerative pathologies. Methods: Sanger sequencing of LRP10 was performed in 233 donors collected by the Netherlands Brain Bank. Results: Rare, possibly pathogenic heterozygous LRP10 variants were present in three patients: p.Gly453Ser in a patient with mixed Alzheimer’s disease (AD)/Lewy body disease (LBD), p.Arg151Cys in a DLB patient, and p.Gly326Asp in an AD patient without LP. All three patients had a positive family history for dementia or PD. Conclusion: Rare LRP10 variants are present in some patients with dementia and different brain pathologies including DLB, mixed AD/LBD, and AD. These findings suggest a role for LRP10 across a broad neurodegenerative spectrum.

Introduction: With increasing age, neuropathological substrates associated with Alzheimer's disease (AD) accumulate in brains of cognitively healthy individuals—are they resilient, or resistant to AD-associated neuropathologies?. Methods: In 85 centenarian brains, we correlated NIA (amyloid) stages, Braak (neurofibrillary tangle) stages, and CERAD (neuritic plaque) scores with cognitive performance close to death as determined by Mini-Mental State Examination (MMSE) scores. We assessed centenarian brains against 2131 brains from AD patients, non-AD demented, and non-demented individuals in an age continuum ranging from 16 to 100+ years. Results: With age, brains from non-demented individuals reached the NIA and Braak stages observed in AD patients, while CERAD scores remained lower. In centenarians, NIA stages varied (22.4% were the highest stage 3), Braak stages rarely exceeded stage IV (5.9% were V), and CERAD scores rarely exceeded 2 (4.7% were 3); within these distributions, we observed no correlation with the MMSE (NIA: P = 0.60; Braak: P = 0.08; CERAD: P = 0.16). Discussion: Cognitive health can be maintained despite the accumulation of high levels of AD-related neuropathological substrates. Highlights: Cognitively healthy elderly have AD neuropathology levels similar to AD patients. AD neuropathology loads do not correlate with cognitive performance in centenarians. Some centenarians are resilient to the highest levels of AD neuropathology.

Background Intratumoral heterogeneity is a hallmark of diffuse gliomas. DNA methylation profiling is an emerging approach in the clinical classification of brain tumors. The goal of this study is to investigate the effects of intratumoral heterogeneity on classification confidence. Methods We used neuronavigation to acquire 133 image-guided and spatially separated stereotactic biopsy samples from 16 adult patients with a diffuse glioma (7 IDH-wildtype and 2 IDH-mutant glioblastoma, 6 diffuse astrocytoma, IDH-mutant and 1 oligodendroglioma, IDH-mutant and 1p19q codeleted), which we characterized using DNA methylation arrays. Samples were obtained from regions with and without abnormalities on contrast-enhanced T1-weighted and fluid-attenuated inversion recovery MRI. Methylation profiles were analyzed to devise a 3-dimensional reconstruction of (epi)genetic heterogeneity. Tumor purity was assessed from clonal methylation sites. Results Molecular aberrations indicated that tumor was found outside imaging abnormalities, underlining the infiltrative nature of this tumor and the limitations of current routine imaging modalities. We demonstrate that tumor purity is highly variable between samples and explains a substantial part of apparent epigenetic spatial heterogeneity. We observed that DNA methylation subtypes are often, but not always, conserved in space taking tumor purity and prediction accuracy into account. Conclusion Our results underscore the infiltrative nature of diffuse gliomas and suggest that DNA methylation subtypes are relatively concordant in this tumor type, although some heterogeneity exists.

The accumulation of fibrillar amyloid-β (Aβ) peptides alongside or within the cerebral vasculature is the hallmark of cerebral amyloid angiopathy (CAA). This condition commonly co-occurs with Alzheimer's disease (AD) and leads to cerebral microbleeds, intracranial hemorrhages, and stroke. CAA also occurs sporadically in an age-dependent fashion and can be accelerated by the presence of familial Aβ mutant peptides. Recent studies using Fourier transform infrared (FTIR) spectroscopy of vascular Aβ fibrils derived from rodents containing the double E22Q/D23N mutations indicated the presence of a novel antiparallel β-sheet structure. To address whether this structure is associated solely with the familial mutations or is a common feature of CAA, we propagated Aβ fibrils from human brain vascular tissue of patients diagnosed with nonfamilial CAA. Aβ fibrils were isolated from cerebral blood vessels using laser capture microdissection in which specific amyloid deposits were removed from thin slices of the brain tissue. Transmission electron microscopy revealed that these deposits were organized into a tight meshwork of fibrils, which FTIR measurements showed could serve as seeds to propagate the growth of Aβ40 fibrils for structural studies. Solid-state NMR measurements of the fibrils propagated from vascular amyloid showed they contained a mixture of parallel, in-register, and antiparallel β-sheet structures. The presence of fibrils with antiparallel structure derived from vascular amyloid is distinct from the typical parallel, in-register β-sheet structure that appears in fibrils derived from parenchymal amyloid in AD. These observations reveal that different microenvironments influence the structures of Aβ fibrils in the human brain.

Parkinson’s disease (PD) and dementia with Lewy bodies (DLB) are closely related progressive disorders with no available causal therapy, neuropathologically characterized by intraneuronal aggregates of misfolded α-synuclein. To explore the role of DNA methylation changes in PD and DLB pathogenesis, we performed an epigenome-wide association study (EWAS) of 322 postmortem frontal cortex samples and replicated results in an independent set of 219 donors. We report novel differentially methylated replicating loci associated with Braak Lewy body stage near SFMBT2, PHYHIP, BRF1/PACS2 and DGKG. The DGKG locus also showed evidence of DNA methylation changes in the earliest, preclinical stage of disease. Differentially methylated probes were independent of known PD genetic risk alleles. Meta-analysis provided suggestive evidence for a differentially methylated locus within the chromosomal region affected by the PD-associated 22q11.2 deletion. Our findings elucidate novel disease pathways in PD and DLB and generate hypotheses for future molecular studies of Lewy body pathology.

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are closely related disorders, linked pathologically and genetically by the TAR DNA-binding protein-43 (TDP-43). Pathogenic variants in TARDBP encoding for TDP-43 have been described less frequently in FTD than in ALS, and clinicopathological studies are scarce.1 We previously observed a high frequency of the I383V variant in TARDBP in a Dutch cohort of FTD patients.2 Here, we provide further evidence for the pathogenicity of this variant and present its clinicopathological characteristics. We ascertained all FTD (n=13) and ALS patients (n=4) with the I383V variant (NM_007375.3: c.1147A>G, p.Ile383Val) in TARDBP from three university medical centres in the Netherlands (Amsterdam, Rotterdam and Utrecht), as identified by whole-exome or whole-genome sequencing in either clinical or research setting. Concurrent pathogenic variants in 20 other genes associated with ALS, FTD or other forms of dementia were excluded in all patients. Brain imaging (CT or MRI) was available for all FTD patients. Quantitative assessment of volume loss across lobar brain regions was performed in those patients with T1-weighted MRI images of sufficient quality (n=5), and compared with a gender-matched/age-matched reference population. Family histories were classified into adjusted Goldman categories, which were described previously.2 Additionally, we performed extensive genealogical research to investigate possible relatedness between the index patients. Brain autopsy and routine immunohistochemistry was performed for two FTD patients by the Netherlands Brain Bank. One patient (4M) was reported previously as M008015-001.1 Detailed information on the genetic, neuroimaging, genealogical and pathological analyses can be found in the1. ### Supplementary data [jnnp-2020-325150supp001.pdf] ### The variable clinical phenotype and reduced penetrance of the I383V variant All 13 FTD patients with the I383V variant in TARDBP presented with a combination of behavioural changes and semantic deficits. The diagnoses of semantic variant of primary progressive aphasia (svPPA) are intriguing since this is usually considered a sporadic disorder. One patient (4M) showed additional motor …

Cognitive deficits in Alzheimer’s disease, specifically amnestic (memory dominant) deficits, are associated with cholinergic degeneration in the basal forebrain. The cholinergic nucleus within the basal forebrain, the nucleus basalis of Meynert, exhibits local atrophy and reduced cortical tract integrity on MRI, and reveals amyloid-β and phosphorylated-tau pathology at autopsy. To better understand the pathophysiology of nucleus basalis of Meynert atrophy and its neocortical projections in Alzheimer’s disease, we utilized a combined post-mortem in-situ MRI and histopathology approach. A total of 19 Alzheimer’s disease (10 amnestic and 9 non-amnestic) and 9 non-neurological control donors underwent 3T T1-weighted MRI for anatomical delineation and volume assessment of the nucleus basalis of Meynert, and diffusion-weighted imaging for microstructural assessment of the nucleus and its projections. At subsequent brain autopsy, tissue dissection and immunohistochemistry were performed for amyloid-β, phosphorylated-tau and choline acetyltransferase. Compared to controls, we observed an MRI-derived volume reduction and altered microstructural integrity of the nucleus basalis of Meynert in Alzheimer’s disease donors. Furthermore, decreased cholinergic cell density was associated with reduced integrity of the nucleus and its tracts to the temporal lobe, specifically to the temporal pole of the superior temporal gyrus, and the parahippocampal gyrus. The association between cholinergic cell density and alteration to cortical tracts was specific for amnestic, compared to non-amnestic Alzheimer’s disease donors. Our study illustrates that the nucleus basalis of Meynert is severely affected in amnestic Alzheimer’s disease, both in terms of pathology within the nucleus, but also in terms of damage to its cortical projections, specifically to the temporal lobe, which may contribute to the observed cognitive deterioration.

INTRODUCTIONThe aim of this study was to identify the histopathological correlates of MRI cortical atrophy in (a)typical Alzheimer’s disease (AD) donors.METHODS19 AD and 10 control donors underwent post-mortem in-situ 3T-3DT1-MRI, from which cortical thickness was calculated. Upon subsequent autopsy, 21 cortical brain regions were selected and immunostained for amyloid-beta, phosphorylated-tau, and reactive microglia. MRI-pathology associations were assessed using linear mixed models. Post-mortem MRI was compared to ante-mortem MRI when available.RESULTSHigher amyloid-beta load weakly correlated with a higher cortical thickness globally. Phosphorylated-tau strongly correlated with cortical atrophy in temporo-frontal regions. Reactive microglia load strongly correlated with cortical atrophy in the parietal region. Post-mortem scans showed high concordance with ante-mortem scans acquired DISCUSSIONDistinct histopathological markers differently correlate with cortical atrophy, highlighting their different roles in the neurodegenerative process. This study contributes in understanding the pathological underpinnings of MRI atrophy patterns.

Although the right temporal variant frontotemporal dementia (rtvFTD) is characterised by distinct clinical and radiological features, its underlying histopathology remains elusive. Being considered a right-sided variant of semantic variant primary progressive aphasia (svPPA), TDP-43 type C pathology has been linked to the syndrome, but this has not been studied in detail in large cohorts. In this case report and systematic review, we report the autopsy results of five subjects diagnosed with rtvFTD from our cohort and 44 single rtvFTD subjects from the literature. Macroscopic pathological evaluation of the combined results revealed that rtvFTD demonstrated either a frontotemporal or temporal evolution, even if the degeneration started in the right temporal lobe initially. FTLD-TDP type C was the most common underlying pathology in rtvFTD, however, in 64% of rtvFTD, other underlying pathologies than FTLD-TDP type C were present, such as Tau-MAPT and FTLD-TDP type A and B. Additionally, accompanying motor neuron or corticospinal tract degeneration was observed in 28% of rtvFTD patients. Our results show that in contrast to the general assumption, rtvFTD might not be a pure FTLD-TDP type C disorder, unlike its left temporal counterpart svPPA. Large sample size pathological studies are warranted to understand the diverse pathologies of the right and left temporal variants of frontotemporal dementia. Supplementary Information The online version contains supplementary material available at 10.1186/s40478-021-01229-z.

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare, fatal, neurodegenerative disease caused by accumulation of abnormally folded prion protein. sCJD can have a long asymptomatic incubation period, with little known about this period. We describe the first-ever participant within the population-based Rotterdam Study diagnosed with sCJD. We retrieved clinical data from both the population-based Rotterdam Study and the National Prion Disease Registry. In 2011, a female participant of the Rotterdam Study was diagnosed with probable sCJD and registered into the Registry. Four months earlier, she was classified as having mild cognitive impairment based on assessment in the Rotterdam Study. Clinical deterioration was rapid, with the patient dying 7 months after the research centre visit. Postmortem brain autopsy confirmed the diagnosis of sCJD. In conclusion, we describe the first case diagnosed with sCJD who during diagnostic workup for sCJD was classified as having mild cognitive impairment in a population-based cohort study.

A repeat expansion in the C9orf72 gene is the most prevalent genetic cause of frontotemporal dementia (C9-FTD). Several studies have indicated the involvement of the unfolded protein response (UPR) in C9-FTD. In human neuropathology, UPR markers are strongly associated with granulovacuolar degeneration (GVD). In this study, we aim to assess the presence of UPR markers together with the presence of dipeptide pathology and GVD in post mortem brain tissue from C9-FTD cases and neurologically healthy controls. Using immunohistochemistry we assessed the presence of phosphorylated PERK, IRE1α and eIF2α in the frontal cortex, hippocampus and cerebellum of C9-FTD (n = 18) and control (n = 9) cases. The presence of UPR activation markers was compared with the occurrence of pTDP-43, p62 and dipeptide repeat (DPR) proteins (poly(GA), -(GR) & -(GP)) as well as casein kinase 1 delta (CK1δ), a marker for GVD. Increased presence of UPR markers was observed in the hippocampus and cerebellum in C9-FTD compared to control cases. In the hippocampus, overall levels of pPERK and peIF2α were higher in C9-FTD, including in granule cells of the dentate gyrus (DG). UPR markers were also observed in granule cells of the cerebellum in C9-FTD. In addition, increased levels of CK1δ were observed in granule cells in the DG of the hippocampus and granular layer of the cerebellum in C9-FTD. Double-labelling experiments indicate a strong association between UPR markers and the presence of dipeptide pathology as well as GVD. We conclude that UPR markers are increased in C9-FTD and that their presence is associated with dipeptide pathology and GVD. Increased presence of UPR markers and CK1δ in granule cells in the cerebellum and hippocampus could be a unique feature of C9-FTD.

A clinical syndrome with neuropsychiatric features of bvFTD without neuroimaging abnormalities and a lack of decline is a phenocopy of bvFTD (phFTD). Growing evidence suggests that psychological, psychiatric and environmental factors underlie phFTD. We describe a patient diagnosed with bvFTD prior to the revision of the diagnostic guidelines of FTD. Repeated neuroimaging was normal and there was no FTD pathology at autopsy, rejecting the diagnosis. We hypothesize on etiological factors that on hindsight might have played a role. This case report contributes to the understanding of phFTD and adds to the sparse literature of the postmortem assessment of phFTD.

Alzheimer’s disease is characterized by cortical atrophy on MRI and abnormal depositions of amyloid-beta, phosphorylated-tau and inflammation pathologically. However, the relative contribution of these pathological hallmarks to cortical atrophy, a widely used MRI biomarker in Alzheimer’s disease, is yet to be defined. Therefore, the aim of this study was to identify the histopathological correlates of MRI cortical atrophy in Alzheimer’s disease donors, and its typical amnestic and atypical non-amnestic phenotypes. Nineteen Alzheimer’s disease (of which 10 typical and 9 atypical) and 10 non-neurological control brain donors underwent post-mortem in situ 3T 3D-T1, from which cortical thickness was calculated with Freesurfer. Upon subsequent autopsy, 12 cortical brain regions from the right hemisphere and 9 from the left hemisphere were dissected and immunostained for amyloid-beta, phosphorylated-tau and reactive microglia, and percentage area load was calculated for each marker using ImageJ. In addition, post-mortem MRI was compared to ante-mortem MRI of the same Alzheimer’s disease donors when available. MRI-pathology associations were assessed using linear mixed models. Higher amyloid-beta load weakly correlated with higher cortical thickness globally (r = 0.22, P = 0.022). Phosphorylated-tau strongly correlated with cortical atrophy in temporal and frontal regions (−0.76 < r < −1.00, all P < 0.05). Reactive microglia load strongly correlated with cortical atrophy in the parietal region (r = −0.94, P < 0.001). Moreover, post-mortem MRI scans showed high concordance with ante-mortem scans acquired, Frigerio et al. report that in Alzheimer’s disease, amyloid-beta, phosphorylated-tau and reactive microglia load measured with immunohistochemistry, are important correlates of MRI cortical atrophy, acquired both ante-mortem in vivo and post-mortem in situ. In summary, distinct histopathological markers differently correlate with cortical atrophy, highlighting their different roles in the neurodegeneration process., Graphical Abstract Graphical Abstract

Background: Right temporal variant frontotemporal dementia (rtvFTD) has been generally considered as a right sided variant of semantic variant primary progressive aphasia (svPPA), which is a genetically sporadic disorder. Recently, we have shown that rtvFTD has a unique clinical syndrome compared to svPPA and behavioral variant frontotemporal dementia. Objective: We challenge the assumption that rtvFTD is a sporadic, non-familial variant of FTD by identifying potential autosomal dominant inheritance and related genes in rtvFTD. Methods: We collected all subjects with a diagnosis of FTD or primary progressive aphasia who had undergone genetic screening (n = 284) and subsequently who had a genetic variant (n = 48) with a diagnosis of rtvFTD (n = 6) in 2 specialized memory clinics. Results: Genetic variants in FTD related genes were found in 33% of genetically screened rtvFTD cases; including MAPT (n = 4), GRN (n = 1), and TARDBP (n = 1) genes, whereas only one svPPA case had a genetic variant in our combined cohorts. Additionally, 4 out of 6 rtvFTD subjects had a strong family history for dementia. Conclusion: Our results demonstrate that rtvFTD, unlike svPPA, is not a pure sporadic, but a heterogeneous potential genetic variant of FTD, and screening for genetic causes for FTD should be performed in patients with rtvFTD.

The neuropathology of Alzheimer’s disease (AD) is characterized by hyperphosphorylated tau neurofibrillary tangles (NFTs) and amyloid-beta (Aβ) plaques. Aβ plaques are hypothesized to follow a development sequence starting with diffuse plaques, which evolve into more compact plaques and finally mature into the classic cored plaque type. A better molecular understanding of Aβ pathology is crucial, as the role of Aβ plaques in AD pathogenesis is under debate. Here, we studied the deposition and fibrillation of Aβ in different plaque types with label-free infrared and Raman imaging. Fourier-transform infrared (FTIR) and Raman imaging was performed on native snap-frozen brain tissue sections from AD cases and non-demented control cases. Subsequently, the scanned tissue was stained against Aβ and annotated for the different plaque types by an AD neuropathology expert. In total, 160 plaques (68 diffuse, 32 compact, and 60 classic cored plaques) were imaged with FTIR and the results of selected plaques were verified with Raman imaging. In diffuse plaques, we detect evidence of short antiparallel β-sheets, suggesting the presence of Aβ oligomers. Aβ fibrillation significantly increases alongside the proposed plaque development sequence. In classic cored plaques, we spatially resolve cores containing predominantly large parallel β-sheets, indicating Aβ fibrils. Combining label-free vibrational imaging and immunohistochemistry on brain tissue samples of AD and non-demented cases provides novel insight into the spatial distribution of the Aβ conformations in different plaque types. This way, we reconstruct the development process of Aβ plaques in human brain tissue, provide insight into Aβ fibrillation in the brain, and support the plaque development hypothesis. Electronic supplementary material The online version of this article (10.1186/s40478-020-01091-5) contains supplementary material, which is available to authorized users.

Alzheimer’s disease (AD) is characterized by amyloid-beta (Aβ) deposits, which come in myriad morphologies with varying clinical relevance. Previously, we observed an atypical Aβ deposit, referred to as the coarse-grained plaque. In this study, we evaluate the plaque’s association with clinical disease and perform in-depth immunohistochemical and morphological characterization. The coarse-grained plaque, a relatively large (Ø ≈ 80 µm) deposit, characterized as having multiple cores and Aβ-devoid pores, was prominent in the neocortex. The plaque was semi-quantitatively scored in the middle frontal gyrus of Aβ-positive cases (n = 74), including non-demented cases (n = 15), early-onset (EO)AD (n = 38), and late-onset (LO)AD cases (n = 21). The coarse-grained plaque was only observed in cases with clinical dementia and more frequently present in EOAD compared to LOAD. This plaque was associated with a homozygous APOE ε4 status and cerebral amyloid angiopathy (CAA). In-depth characterization was done by studying the coarse-grained plaque’s neuritic component (pTau, APP, PrPC), Aβ isoform composition (Aβ40, Aβ42, AβN3pE, pSer8Aβ), its neuroinflammatory component (C4b, CD68, MHC-II, GFAP), and its vascular attribution (laminin, collagen IV, norrin). The plaque was compared to the classic cored plaque, cotton wool plaque, and CAA. Similar to CAA but different from classic cored plaques, the coarse-grained plaque was predominantly composed of Aβ40. Furthermore, the coarse-grained plaque was distinctly associated with both intense neuroinflammation and vascular (capillary) pathology. Confocal laser scanning microscopy (CLSM) and 3D analysis revealed for most coarse-grained plaques a particular Aβ40 shell structure and a direct relation with vessels. Based on its morphological and biochemical characteristics, we conclude that the coarse-grained plaque is a divergent Aβ plaque-type associated with EOAD. Differences in Aβ processing and aggregation, neuroinflammatory response, and vascular clearance may presumably underlie the difference between coarse-grained plaques and other Aβ deposits. Disentangling specific Aβ deposits between AD subgroups may be important in the search for disease-mechanistic-based therapies.

ObjectiveAccumulation of amyloid-β is among the earliest changes in Alzheimer’s disease (AD). Amyloid-β positron emission tomography (PET) and Aβ42 in cerebrospinal fluid (CSF) both assess amyloid-β pathology in-vivo, but 10–20% of cases show discordant (CSF+/PET- or CSF-/PET+) results. The neuropathological correspondence with amyloid-β CSF/PET discordance is unknown.MethodsWe included 21 patients from our tertiary memory clinic who had undergone both CSF Aβ42 analysis and amyloid-β PET, and had neuropathological data available. Amyloid-β PET and CSF results were compared with neuropathological ABC scores (comprising of Thal (A), Braak (B) and CERAD (C) stage, all ranging from 0 [low] to 3 [high]) and neuropathological diagnosis.ResultsNeuropathological diagnosis was AD in 11 (52%) patients. Amyloid-β PET was positive in all A3, C2 and C3 cases and in one of the two A2 cases. CSF Aβ42 was positive in 92% of A2/A3 and 90% of C2/C3 cases. PET and CSF were discordant in 3/21 (14%) cases: CSF+/PET- in a patient with granulomatosis with polyangiitis (A0B0C0), CSF+/PET- in a patient with FTLD-TDP type B (A2B1C1), and CSF-/PET+ in a patient with AD (A3B3C3). Two CSF+/PET+ cases had a non-AD neuropathological diagnosis, i.e. FTLD-TDP type E (A3B1C1) and adult-onset leukoencephalopathy with axonal spheroids (A1B1C0).InterpretationOur findings confirm amyloid-β CSF/PET discordance with a range of possible reasons. Furthermore, amyloid-β biomarker positivity on both PET and CSF did not invariably result in an AD diagnosis at autopsy, illustrating the importance of considering relevant co-morbidities when evaluating amyloid-β biomarker results.

Knowledge about the molecular mechanisms driving Alzheimer's disease (AD) is still limited. To learn more about AD biology, we performed whole transcriptome sequencing on the hippocampus of 20 AD cases and 10 age- and sex-matched cognitively healthy controls. We observed 2716 differentially expressed genes, of which 48% replicated in a second data set of 84 AD cases and 33 controls. We used an integrative network-based approach for combining transcriptomic and protein-protein interaction data to find differentially expressed gene modules that may reflect key processes in AD biology. A total of 735 differentially expressed genes were clustered into 33 modules, of which 82% replicated in a second data set, highlighting the robustness of this approach. These 27 modules were enriched for signal transduction, transport, response to stimulus, and several organic and cellular metabolic pathways. Ten modules interacted with previously described AD genes. Our study indicates that analyzing RNA-expression data based on annotated gene modules is more robust than on individual genes. We provide a comprehensive overview of the biological processes involved in AD, and the detected differentially expressed gene modules may provide a molecular basis for future research into mechanisms underlying AD.

Aims: The behavioural variant of frontotemporal dementia with a C9orf72 expansion (C9-bvFTD) is characterised by early changes in social-emotional cognition that are linked to the loss of von Economo neurons (VENs). Together with a subset of neighbouring pyramidal neurons, VENs express the GABA receptor subunit theta (GABRQ). It is not known if the selective vulnerability of VENs in C9-bvFTD also includes this GABRQ-expressing population. Methods: We quantified VENs and GABRQ immunopositive neurons in the anterior cingulate cortex (ACC) in C9-bvFTD (n = 16), controls (n = 12) and Alzheimer's disease (AD) (n = 7). Second, we assessed VENs and GABRQ-expressing populations in relation to the clinicopathological profiles. Results: We found the number of VENs and GABRQ-expressing neurons and their ratio over the total layer 5 neuronal population was lower in C9-bvFTD compared to control and AD. C9-bvFTD donors with underlying TDP43 type A pathology in the ACC showed the highest loss of GABRQ-expressing neurons. C9-bvFTD donors that did not present with motor neuron disease (MND) symptoms in the first half of their disease course showed a prominent loss of GABRQ-expressing neurons compared to controls. C9-bvFTD donors with no symptoms of psychosis showed a higher loss compared to controls. Across all donors, the number of VENs correlated strongly with the number of GABRQ-expressing neurons. Conclusion: We show that VENs, together with GABRQ-expressing neurons, are selectively vulnerable in C9-bvFTD but are both spared in AD. This suggests they are related and that this GABRQ-expressing population of VENs and pyramidal neurons, is a key modulator of social-emotional functioning.

Intratumoral heterogeneity is a hallmark of diffuse gliomas. We used neuronavigation to acquire 133 image-guided and spatially-separated stereotactic biopsy samples from 16 adult patients with a diffuse glioma, which we characterized using DNA methylation arrays. Samples were obtained from regions with and without imaging abnormalities. Methylation profiles were analyzed to devise a three-dimensional reconstruction of genetic and epigenetic heterogeneity. Molecular aberrations indicated that tumor was found outside imaging abnormalities, underlining the infiltrative nature of this tumor and the limitations of current routine imaging modalities. We demonstrate that tumor purity is highly variable between samples and largely explains apparent epigenetic spatial heterogeneity. Indeed, we observed that DNA methylation subtypes are highly conserved in space after adjusting for tumor purity. Genome-wide heterogeneity analysis showed equal or increased heterogeneity among normal tissue when compared to tumor. These findings were validated in a separate cohort of 61 multi-sector tumor and 64 normal samples. Our findings underscore the infiltrative nature of diffuse gliomas and suggest that heterogeneity in DNA methylation is innate to somatic cells and not a characteristic feature of this tumor type.

Gluten-related neurological disorders (GRND) represent a spectrum of neurological manifestations that are triggered by gluten. In coeliac disease, a T-cell mediated enteropathy is triggered by gluten in genetically predisposed individuals. The underlying pathological mechanism of the neurological dysfunction is not yet clear. The aim of this review is to collate existing neuropathological findings in GRND as a means of aiding the understanding of the pathophysiology. A systematic search of the Pubmed Database yielded 188 articles, of which 32 were included, containing 98 eligible cases with a description of pathological findings in GRND. In gluten ataxia, loss of Purkinje cells, atrophy, gliosis and astrocytosis were apparent, as well as diffuse lymphocytic infiltration and perivascular cuffing with lymphocytes. In patients with large-fiber neuropathy, nerve biopsies revealed axonopathy, loss of myelinated fibers and focal and perivascular infiltration by inflammatory cells. Inflammatory infiltrate was also observed in muscle in myopathy and in cerebrum of patients with encephalopathy and patients with epilepsy. Such changes were not seen in skin biopsies from patients with small fiber neuropathies. The findings from this systematic review suggest an immune mediated pathogenesis for GRND. Future research should focus on the characterization of the inflammatory cell infiltrates and identifying target epitopes.

The combined fluorescent and Aβ-binding properties of the dietary spice curcumin could yield diagnostic purpose in the search for a non-invasive Aβ-biomarker for Alzheimer’s disease (AD). However, evidence on the binding properties of curcumin, its conjugates and clinically used bio-available formulations to AD neuropathological hallmarks is scarce. We therefore assessed the binding properties of different curcumin forms to different neuropathological deposits in post-mortem brain tissue of cases with AD, other neurodegenerative diseases, and controls. Post mortem brain tissue was histochemically assessed for the binding of curcumin, its isoforms, conjugates and bio-available forms and compared to routinely used staining methods. For this study we included brains of early onset AD, late onset AD, primary age-related tauopathy (PART), cerebral amyloid angiopathy (CAA), frontotemporal lobar degeneration (FTLD) with tau or TAR DNA-binding protein 43 (TDP-43) inclusions, dementia with Lewy bodies (DLB), Parkinson’s disease (PD) and control cases without brain pathology. We found that curcumin binds to fibrillar amyloid beta (Aβ) in plaques and CAA. It does not specifically bind to inclusions of protein aggregates in FTLD-tau cases, TDP-43, or Lewy bodies. Curcumin isoforms, conjugates and bio-available forms show affinity for the same Aβ structures. Curcumin staining overlaps with immunohistochemical detection of Aβ in fibrillar plaques and CAA, and to a lesser extent cored plaques. A weak staining of neurofibrillary tangles was observed, while other structures immunopositive for phosphorylated tau remained negative. In conclusion, curcumin, its isoforms, conjugates and bio-available forms selectively bind fibrillar Aβ in plaques and CAA in post mortem AD brain tissue. Curcumin, being a food additive with fluorescent properties, is therefore an interesting candidate for in-vivo diagnostics in AD, for example in retinal fluorescent imaging.

With aging, the incidence of neuropathological hallmarks of neurodegenerative diseases increases in the brains of cognitively healthy individuals. It is currently unclear to what extent these hallmarks associate with symptoms of disease at extreme ages. Forty centenarians from the 100-plus Study cohort donated their brain. Centenarians self-reported to be cognitively healthy at baseline, which was confirmed by a proxy. Objective ante-mortem measurements of cognitive performance were associated with the prevalence, distribution and quantity of age- and AD-related neuropathological hallmarks. Despite self-reported cognitive health, objective neuropsychological testing suggested varying levels of ante-mortem cognitive functioning. Post-mortem, we found that neuropathological hallmarks related to age and neurodegenerative diseases, such as Aβ and Tau pathology, as well as atherosclerosis, were abundantly present in most or all centenarians, whereas Lewy body and pTDP-43 pathology were scarce. We observed that increased pathology loads correlated across pathology subtypes, and an overall trend of higher pathology loads to associate with a lower cognitive test performance. This trend was carried especially by the presence of neurofibrillary tangles (NFTs) and granulovacuolar degeneration (GVD) and to a lesser extent by Aβ-associated pathologies. Cerebral Amyloid Angiopathy (CAA) specifically associated with lower executive functioning in the centenarians. In conclusion, we find that while the centenarians in this cohort escaped or delayed cognitive impairment until extreme ages, their brains reveal varying levels of disease-associated neuropathological hallmarks, some of which associate with cognitive performance. Electronic supplementary material The online version of this article (10.1186/s40478-018-0558-5) contains supplementary material, which is available to authorized users.

Aim: The insular cortex consists of a heterogenous cytoarchitecture and diverse connections and is thought to integrate autonomic, cognitive, emotional and interoceptive functions to guide behaviour. In Parkinson's disease (PD) and dementia with Lewy bodies (DLB), it reveals α-synuclein pathology in advanced stages. The aim of this study is to assess the insular cortex cellular and subregional vulnerability to α-synuclein pathology in well-characterized PD and DLB subjects. Methods: We analysed postmortem insular tissue from 24 donors with incidental Lewy body disease, PD, PD with dementia (PDD), DLB and age-matched controls. The load and distribution of α-synuclein pathology and tyrosine hydroxylase (TH) cells were studied throughout the insular subregions. The selective involvement of von Economo neurons (VENs) in the anterior insula and astroglia was assessed in all groups. Results: A decreasing gradient of α-synuclein pathology load from the anterior periallocortical agranular towards the intermediate dysgranular and posterior isocortical granular insular subregions was found. Few VENs revealed α-synuclein inclusions while astroglial synucleinopathy was a predominant feature in PDD and DLB. TH neurons were predominant in the agranular and dysgranular subregions but did not reveal α-synuclein inclusions or significant reduction in density in patient groups. Conclusions: Our study highlights the vulnerability of the anterior agranular insula to α-synuclein pathology in PD, PDD and DLB. Whereas VENs and astrocytes were affected in advanced disease stages, insular TH neurons were spared. Owing to the anterior insula's affective, cognitive and autonomic functions, its greater vulnerability to pathology indicates a potential contribution to nonmotor deficits in PD and DLB.

ObjectiveTo examine the clinical value of neurofilament light chain (NfL) and the phospho-tau/total tau ratio (p/t-tau) across the entire frontotemporal dementia (FTD) spectrum in a large, well-defined cohort.MethodsCSF NfL and p/t-tau levels were studied in 361 patients with FTD: 179 behavioral variant FTD, 17 FTD with motor neuron disease (FTD-MND), 36 semantic variant primary progressive aphasia (PPA), 19 nonfluent variant PPA, 4 logopenic variant PPA (lvPPA), 42 corticobasal syndrome, and 64 progressive supranuclear palsy. Forty-five cognitively healthy controls were also included. Definite pathology was known in 68 patients (49 frontotemporal lobar degeneration [FTLD]-TDP, 18 FTLD-tau, 1 FTLD-FUS).ResultsNfL was higher in all diagnoses, except lvPPA (n = 4), than in controls, equally elevated in behavioral variant FTD, semantic variant PPA, nonfluent variant PPA, and corticobasal syndrome, and highest in FTD-MND. The p/t-tau was lower in all clinical groups, except lvPPA, than in controls and lowest in FTD-MND. NfL did not discriminate between TDP and tau pathology, while the p/t-tau ratio had a good specificity (76%) and moderate sensitivity (67%). Both high NfL and low p/t-tau were associated with poor survival (hazard ratio on tertiles 1.7 for NfL, 0.7 for p/t-tau).ConclusionNfL and p/t-tau similarly discriminated FTD from controls, but not between clinical subtypes, apart from FTD-MND. Both markers predicted survival and are promising monitoring biomarkers for clinical trials. Of note, p/t-tau, but not NfL, was specific to discriminate TDP from tau pathology in vivo.Classification of evidenceThis study provides Class III evidence that for patients with cognitive issues, CSF NfL and p/t-tau levels discriminate between those with and without FTD spectrum disorders.

Creutzfeldt–Jakob disease is a rare, fatal, neurodegenerative disease caused by the accumulation of abnormally folded prion proteins. The common polymorphism at codon 129 (methionine/valine) in the prion protein (PRNP) gene is the most important determinant of genetic susceptibility. Homozygotes of either allele have a higher risk of sporadic Creutzfeldt–Jakob disease. Various studies suggest that this polymorphism is also involved in other forms of dementia. We studied the association between the codon 129 polymorphism of the PRNP gene and mild cognitive impairment in 3605 participants from the Rotterdam Study using logistic regression analyses. Subsequently, we studied the association between this polymorphism and incident dementia, including Alzheimer’s disease, in 11 070 participants using Cox proportional hazard models. Analyses were adjusted for age and sex. We found the prevalence of mild cognitive impairment to be higher for carriers of the methionine/methionine genotype (odds ratio, 1.40; 95% confidence interval, 1.11–1.78; P = 0.005) as well as for carriers of the valine/valine genotype (odds ratio, 1.37; 95% confidence interval, 0.96–1.97; P = 0.08). The codon 129 polymorphism was not associated with the risk of incident dementia or Alzheimer’s disease. In conclusion, we found a statistically significant higher prevalence of mild cognitive impairment in carriers of the methionine/methionine genotype in the codon 129 polymorphism of the PRNP gene within this population-based study. No associations were found between the codon 129 polymorphism and dementia or Alzheimer’s disease in the general population., There is increasing interest in the role of the common polymorphism at codon 129 in the prion protein gene in neurodegenerative traits. We report a role of this polymorphism in mild cognitive impairment in the general population. However, no association was found with dementia., Graphical Abstract Graphical Abstract

While diffuse gliomas are notorious for their histopathological, genetic and transcriptional spatial heterogeneity, little is known about their epigenetic spatial heterogeneity. The result of spatial (epi)genetic analysis is strongly influenced by the proportion of cancer cells in a sample, so called tumor purity. However, a gold standard for assessment of tumor purity is lacking. We set out to analyze tumor purity using different measurement modalities and explore tumor purity-corrected DNA methylation spatial heterogeneity in glioma. DNA methylation(-derived), quantitative histological and radiological measurements of tumor purity, as well as DNA methylation profiles, were analyzed in 133 image-guided multi-sector stereotactic biopsy samples of 16 patients with newly diagnosed glioma. These biopsies were acquired in regions with and without abnormalities on MRI. Data was validated in two independent populations of respectively 102 multi-region samples in 24 glioma patients and 64 single-region samples from patients without glioma. DNA methylation profiles from The Cancer Genome Atlas and the patients without glioma was used to predict DNA methylation and transcriptional subtype. Consensus measurement of tumor purity estimates (CPE) ranged from 0 to 91% and was most correlated with the DNA methylation measurement of tumor purity. Neuropathological qualitative assessment of tumor presence generally corresponded well with CPE, but occasionally samples reported as ‘histologically normal’ demonstrated tumor purities up to 53%. After filtering specimens with tumor purity less than 50%, DNA methylation subtype showed little spatial heterogeneity, this in contrast to transcriptional subtype. Samples from core and peripheral regions showed similar DNA methylation profiles. Non-purity related intratumoral heterogeneity for promotor methylation of epigenetically regulated genes was minimal, but higher in IDH-wildtype than in IDH-mutant gliomas. In conclusion, after considering DNA methylation-based measurement of tumor purity DNA methylation in diffuse gliomas shows little spatial heterogeneity; incorporating such tumor purity information can further increase the reliability of methylation-profiling-based tumor classification.

Distinguishing tumors from normal brain cells is important but challenging in glioma surgery due to the lack of clear interfaces between the two. The ability of label‐free third harmonic generation (THG) microscopy in combination with automated image analysis to quantitatively detect glioma infiltration in fresh, unprocessed tissue in real time is assessed. The THG images reveal increased cellularity in grades II–IV glioma samples from 23 patients, as confirmed by subsequent hematoxylin and eosin histology. An automated image quantification workflow is presented for quantitative assessment of the imaged cellularity as a reflection of the degree of glioma invasion. The cellularity is validated in three ways: 1) Quantitative comparison of THG imaging with fluorescence microscopy of nucleus‐stained samples demonstrates that THG reflects the true tissue cellularity. 2) Thresholding of THG cellularity differentiates normal brain from glioma infiltration, with 96.6% sensitivity and 95.5% specificity, in nearly perfect (93%) agreement with pathologists. 3) In one patient, a good correlation between THG cellularity and preoperative magnetic resonance and positron emission tomography imaging is demonstrated. In conclusion, quantitative real‐time THG microscopy accurately assesses glioma infiltration in ex vivo human brain samples, and therefore holds strong potential for improving the accuracy of surgical resection.

ObjectiveDespite the strong genetic component of frontotemporal dementia (FTD), a substantial proportion of patients remain genetically unresolved. We performed an in-depth study of a family with an autosomal dominant form of FTD to investigate the underlying genetic cause.MethodsFollowing clinical and pathologic characterization of the family, genetic studies included haplotype sharing analysis and exome sequencing. Subsequently, we performed immunohistochemistry, immunoblotting, and a microtubule repolymerization assay to investigate the potential impact of the candidate variant in tubulin alpha 4a (TUBA4A).ResultsThe clinical presentation in this family is heterogeneous, including behavioral changes, parkinsonian features, and uncharacterized dementia. Neuropathologic examination of 2 patients revealed TAR DNA binding protein 43 (TDP-43) pathology with abundant dystrophic neurites and neuronal intranuclear inclusions, consistent with frontotemporal lobar degeneration–TDP type A. We identified a likely pathogenic variant in TUBA4A segregating with disease. TUBA4A encodes for α-tubulin, which is a major component of the microtubule network. Variants in TUBA4A have been suggested as a rare genetic cause of amyotrophic lateral sclerosis (ALS) and have sporadically been reported in patients with FTD without supporting genetic segregation. A decreased trend of TUBA4A protein abundance was observed in patients compared with controls, and a microtubule repolymerization assay demonstrated disrupted α-tubulin function. As opposed to variants found in ALS, TUBA4A variants associated with FTD appear more localized to the N-terminus, indicating different pathogenic mechanisms.ConclusionsOur findings support the role of TUBA4A variants as rare genetic cause of familial FTD.

Background: The majority of patients with Alzheimer’s disease (AD) exhibit amyloid- (A) deposits at the brain vasculature, a process referred to as cerebral amyloid angiopathy (CAA). In over 51% of AD cases, A also accumulates in cortical capillaries, which is termed capillary CAA (capCAA). It has been postulated that the presence of capCAA in AD is a specific subtype of AD, although underlying mechanisms are not yet fully understood. Sphingolipids (SLs) are implicated in neurodegenerative disorders, including AD. However, to date it remains unknown whether alterations in the SL pathway are involved in capCAA pathogenesis and if these differ from AD. 16 17 18 19 20 21 Objective: To determine whether AD cases with capCAA have an altered SL profile compared to AD cases without capCAA. 22 Methods: Immunohistochemistry was performed to assess the expression and localization of ceramide, acid sphingomyelinase (ASM), and sphingosine-1-phosphate receptors (S1P1, S1P3). In addition, we determined the concentrations of S1P as well as different chain-lengths of ceramides using HPLC-MS/MS. 23 24 25 Results: Immunohistochemical analysis revealed an altered expression of ceramide, ASM, and S1P receptors by reactive astrocytes and microglial cells specifically associated with capCAA. Moreover, a shift in the balance of ceramides with different chain-lengths and S1P content is observed in capCAA. 26 27 28 Conclusion: Here we provide evidence of a deregulated SL balance in capCAA. The increased levels of ASM and ceramide in activated glia cells suggest that the SL pathway is involved in the neuroinflammatory response in capCAA pathogenesis. Future research is needed to elucidate the role of S1P in capCAA. 29 30 31

INTRODUCTION: We performed a comprehensive quantitative proteomics study on human hippocampus tissue involving all Braak stages to assess changes in protein abundance over the various stages of Alzheimer's disease (AD).METHODS: Hippocampal subareas CA1 and subiculum of 40 cases were isolated using laser capture microdissection and analyzed using mass spectrometry. Immunoblotting and immunohistochemistry were used for validation.RESULTS: Over the Braak stages, an altered expression was found for 372 proteins including changes in levels of extracellular matrix components, and in calcium-dependent signaling proteins. Early changes were observed in levels of proteins related to cytoskeletal dynamics and synaptic components including an increase in RIMS1 and GRIK4. Several synaptic proteins, such as BSN, LIN7A, DLG2, -3, and -4, exhibit an early-up, late-down expression pattern.DISCUSSION: This study provides new insight into AD-dependent changes in protein levels in the hippocampus during AD pathology, identifying potential novel therapeutic targets and biomarkers.

Next-generation sequencing has contributed to our understanding of the genetics of Alzheimer's disease (AD) and has explained a substantial part of the missing heritability of familial AD. We sequenced 19 exomes from 8 Dutch families with a high AD burden and identified EIF2AK3, encoding for protein kinase RNA-like endoplasmic reticulum kinase (PERK), as a candidate gene. Gene-based burden analysis in a Dutch AD exome cohort containing 547 cases and 1070 controls showed a significant association of EIF2AK3 with AD (OR 1.84 [95% CI 1.07-3.17], p-value 0.03), mainly driven by the variant p.R240H. Genotyping of this variant in an additional cohort from the Rotterdam Study showed a trend toward association with AD (p-value 0.1). Immunohistochemical staining with pPERK and peIF2 alpha of 3 EIF2AK3 AD carriers showed an increase in hippocampal neuronal cells expressing these proteins compared with nondemented controls, but no difference was observed in AD noncarriers. This study suggests that rare variants in EIF2AK3 may be associated with disease risk in AD. (C) 2018 The Authors. Published by Elsevier Inc.

Parkinson's disease, the most common age-related movement disorder, is a progressive neurodegenerative disease with unclear etiology. Key neuropathological hallmarks are Lewy bodies and Lewy neurites: neuronal inclusions immunopositive for the protein alpha-synuclein. In-depth ultrastructural analysis of Lewy pathology is crucial to understanding pathogenesis of this disease. Using correlative light and electron microscopy and tomography on postmortem human brain tissue from Parkinson's disease brain donors, we identified alpha-synuclein immunopositive Lewy pathology and show a crowded environment of membranes therein, including vesicular structures and dysmorphic organelles. Filaments interspersed between the membranes and organelles were identifiable in many but not all alpha-synuclein inclusions. Crowding of organellar components was confirmed by stimulated emission depletion (STED)-based super-resolution microscopy, and high lipid content within alpha-synuclein immunopositive inclusions was corroborated by confocal imaging, Fourier-transform coherent anti-Stokes Raman scattering infrared imaging and lipidomics. Applying such correlative high-resolution imaging and biophysical approaches, we discovered an aggregated protein-lipid compartmentalization not previously described in the Parkinsons' disease brain.