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Tauopathies are a subset of neurodegenerative diseases characterized by abnormal tau inclusions. Specifically, three-repeat tau and four-repeat tau in Alzheimer's disease, three-repeat tau in Pick's disease (PiD) and four-repeat tau in progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) form amyloid-like fibrous structures that accumulate in neurons and/or glial cells. Amplification and cell-to-cell transmission of abnormal tau based on the prion hypothesis are believed to explain the onset and progression of tauopathies. Recent studies support not only the self-propagation of abnormal tau, but also the presence of conformationally distinct tau aggregates, namely tau strains. Cryogenic electron microscopy analyses of patient-derived tau filaments have revealed disease-specific ordered tau structures. However, it remains unclear whether the ultrastructural and biochemical properties of tau strains are inherited during the amplification of abnormal tau in the brain. In this study, we investigated template-dependent amplification of tau aggregates using a cellular model of seeded aggregation. Tau strains extracted from human tauopathies caused strain-dependent accumulation of insoluble filamentous tau in SH-SY5Y cells. The seeding activity towards full-length four-repeat tau substrate was highest in CBD-tau seeds, followed by PSP-tau and Alzheimer's disease (AD)-tau seeds, while AD-tau seeds showed higher seeding activity than PiD-tau seeds towards three-repeat tau substrate. Abnormal tau amplified in cells inherited the ultrastructural and biochemical properties of the original seeds. These results strongly suggest that the structural differences of patient-derived tau strains underlie the diversity of tauopathies, and that seeded aggregation and filament formation mimicking the pathogenesis of sporadic tauopathy can be reproduced in cultured cells. Our results indicate that the disease-specific conformation of tau aggregates determines the tau isoform substrate that is recruited for templated amplification, and also influences the prion-like seeding activity., (© The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain.)

The sigma 1 receptor (S1R) is widely expressed in the CNS and is mainly located on the endoplasmic reticulum. The S1R is involved in the regulation of many neurotransmission systems and, indirectly, in neurodegenerative diseases. The S1R may therefore represent an interesting neuronal biomarker in neurodegenerative diseases such as Parkinson's (PD) or Alzheimer's diseases (AD). Here we present the characterisation of the S1R-specific 18 F-labelled tracer 18 F-IAM6067 in two animal models and in human brain tissue. Methods: Wistar rats were used for PET-CT imaging (60 min dynamic acquisition) and metabolite analysis (1, 2, 5, 10, 20, 60 min post-injection). To verify in vivo selectivity, haloperidol, BD1047 (S1R ligand), CM398 (S2R ligand) and SB206553 (5HT 2B/C antagonist) were administrated for pre-saturation studies. Excitotoxic lesions induced by intra-striatal injection of AMPA were also imaged by 18 F-IAM6067 PET-CT to test the sensitivity of the methods in a well-established model of neuronal loss. Tracer brain uptake was also verified by autoradiography in rats and in a mouse model of PD (intrastriatal 6-hydroxydopamine (6-OHDA) unilateral lesion). Finally, human cortical binding was investigated by autoradiography in three groups of subjects (control subjects with Braak ≤2, and AD patients, Braak >2 & ≤4 and Braak >4 stages). Results: We demonstrate that despite rapid peripheral metabolism of 18 F-IAM6067, radiolabelled metabolites were hardly detected in brain samples. Brain uptake of 18 F-IAM6067 showed differences in S1R anatomical distribution, namely from high to low uptake: pons-raphe, thalamus medio-dorsal, substantia nigra , hypothalamus, cerebellum, cortical areas and striatum. Pre-saturation studies showed 79-90% blockade of the binding in all areas of the brain indicated above except with the 5HT 2B/C antagonist SB206553 and S2R ligand CM398 which induced no significant blockade, indicating good specificity of 18 F-IAM6067 for S1Rs. No difference between ipsi- and contralateral sides of the brain in the mouse model of PD was detected. AMPA lesion induced a significant 69% decrease in 18 F-IAM6067 uptake in the globus pallidus matching the neuronal loss as measured by NeuN, but only a trend to decrease (-16%) in the caudate putamen despite a significant 91% decrease in neuronal count. Moreover, no difference in the human cortical binding was shown between AD groups and controls. Conclusion: This work shows that 18 F-IAM6067 is a specific and selective S1R radiotracer. The absence or small changes in S1R detected here in animal models and human tissue warrants further investigations and suggests that S1R might not be the anticipated ideal biomarker for neuronal loss in neurodegenerative diseases such as AD and PD., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

In the present study, we have characterized and compared individuals whose brains were donated as part of The University of Manchester Longitudinal Study of Cognition in Normal Healthy Old Age (UoM) with those donated through the Manchester arm of the UK Brains for Dementia Research (BDR) program. The aim of this study was to investigate how differences in study recruitment may affect final pathological composition of cohort studies. The UoM cohort was established as a longitudinal study of aging and cognition whereas the BDR program was established, prima facie, to collect brains from both demented and non-demented individuals for the purpose of building a tissue research resource. Consequently, the differences in recruitment patterns generated differences in demographic, clinical, and neuropathological characteristics. There was a higher proportion of recruits with dementia [mostly Alzheimer's disease (AD)] within the BDR cohort than in the UoM cohort. In pathological terms, the BDR cohort was more 'polarized', being more composed of demented cases with high Braak pathology scores and non-demented cases with low Braak scores, and fewer non-AD pathology cases, than the UoM cohort. In both cohorts, cerebral amyloid angiopathy tended to be greater in demented than non-demented individuals. Such observations partly reflect the recruitment of demented and non-demented individuals into the BDR cohort, and also that insufficient study time may have elapsed for disease onset and development in non-demented individuals to take place. Conversely, in the UoM cohort, where there had been nearly 30 years of study time, a broader spread of AD-type pathological changes had 'naturally' evolved in the brains of both demented and non-demented participants.

While post mortem studies have identified the major cell types and functional systems affected in Alzheimer's disease (AD) the initial sites and molecular characteristics of pathology are still unclear. Because individuals with Down syndrome (DS) (trisomy 21) develop the full pathological changes of AD in a predictable way by the time they reach middle to late age, a study of the brains of such persons at different ages makes an ideal 'model system' in which the sites of earliest onset of pathology can be detected and the subsequent progression of changes be monitored. In the present study we have examined the brains of 56 individuals with DS ranging from new-born to 76 years for the presence of amyloid and tau pathology in key cortical and subcortical regions. Amyloid pathology was found to commence in the late teens to twenties as a deposition of diffuse plaques initially within the temporal neocortex, quickly involving other neocortical regions but only reaching subcortical regions and cerebellum by the late forties. Cerebral amyloid angiopathy did not regularly commence until after 45-50 years of age. Tau pathology usually commenced after 35 years of age, initially involving not only entorhinal areas and hippocampus but also subcortical regions such as locus caeruleus (LC) and dorsal raphe nucleus (DRN). Later, tau pathology spread throughout the neocortex reaching occipital lobes in most instances by mid-50 years of age. Such a pattern of spread is consistent with that seen in typical AD. We found no evidence that tau pathology might commence within the brain in DS before amyloid deposition had occurred, but there was limited data that suggests tau pathology in LC or DRN might predate that in entorhinal areas and hippocampus or at least be coincident.

The neuropathological changes responsible for cognitive impairment and dementia remain incompletely understood. Longitudinal studies with a brain donation end point allow the opportunity to examine relationships between cognitive status and neuropathology. We report on the first 97 participants coming to autopsy with sufficient clinical information from The University of Manchester Longitudinal Study of Cognition in Normal Healthy Old Age. This study began in 1983 and recruited 6,542 healthy individuals between 1983 and 1994, 312 of whom consented to brain donation. Alzheimer-type pathology was common throughout the cohort and generally correlated well with cognitive status. However, there was some overlap between cognitive status and measures of Alzheimer pathology with 26% of cognitively intact participants reaching either CERAD B or C, 11% reaching Thal phase 4 or 5, and 29% reaching Braak stage III- VI. Cerebral amyloid angiopathy(CAA), α-synuclein, and TDP-43 pathology was less common, but when present correlated well with cognitive status. Possession of APOEɛ4 allele(s) was associated with more severe Alzheimer-type and CAA pathology and earlier death, whereas possession of APOEɛ2 allele(s) had no effect on pathology but was more common in cognitively intact individuals. The University of Manchester Longitudinal Study of Cognition in Normal Healthy Old Age cohort is pathologically representative when compared with similar studies. Cognitive impairment in life correlates strongly with all pathologies examined and the APOE status of an individual can affect pathology severity and longevity.

Frontotemporal Lobar Degeneration (FTLD) encompasses certain related neurodegenerative disorders which alter personality and cognition. Heterogeneous ribonuclear proteins (hnRNPs) maintain RNA metabolism and changes in their function may underpin the pathogenesis of FTLD. Immunostaining for hnRNP E2 was performed on sections of frontal and temporal cortex with hippocampus from 80 patients with FTLD, stratified by pathology into FTLD-tau and FTLD-TDP type A, B and C subtypes, and by genetics into patients with C9orf72 expansions, MAPT or GRN mutations, or those with no known mutation, and on 10 healthy controls. Semi-quantitative analysis assessed hnRNP staining in frontal and temporal cortex, and in dentate gyrus (DG) of hippocampus, in the different pathology and genetic groups. We find that hnRNP E2 immunostaining detects the TDP-43 positive dystrophic neurites (DN) within frontal and temporal cortex, and the neuronal cytoplasmic inclusions (NCI) seen in DG granule cells, characteristic of patients with Semantic Dementia (SD) and type C TDP-43 pathology, but did not detect TDP-43 or tau inclusions in any of the other pathological or genetic variants of FTLD. Double immunofluorescence for hnRNP E2 and TDP-43 showed most TDP-43 immunopositive DN to contain hnRNP E2. Present findings indicate an association between TDP-43 and hnRNP E2 which might underlie the pathogenetic mechanism of this form of FTLD.

Aims: Microglia-driven neuroinflammation can play an important role in the pathophysiology of neurodegenerative disorders. In this study, we sought to characterize the distribution of microglial cell activation in 2 neurodegenerative dementias with distinct protein signatures, Alzheimer disease (AD) and frontotemporal lobar degeneration (FTLD) of the TDP subtype, and to determine if there was an anatomical correlation with the phenotypes most commonly associated with these conditions., Methods: The distribution and extent of microglial cell activation was assessed semiquantitatively in the hippocampal formation, cortical gray matter, and subcortical white matter of CD68-immunostained sections of the frontal, temporal, parietal, and occipital cortices from 15 pathologically confirmed cases of AD, 13 cases of FTLD, and 18 controls., Results: Significantly higher levels of microglial cell activation occurred in the subiculum in AD and FTLD than in controls. Additionally, AD had higher microglial activation in the CA1 and FTLD in the hippocampal white matter than the controls. Microglial activation was greater in the dentate gyrus molecular layer in AD than in FTLD. In the cortical regions, the 2 pathological groups differed only in frontal white matter, with the FTLD group showing higher microglial scores. FTLD showed higher microglial activation in the white matter compared to the respective gray matter in the entorhinal, temporal, and frontal regions., Conclusions: Our work expands the knowledge of the distribution and magnitude of microglial activation in these disorders. Additionally, we found some microglial circuit-specific patterns that could help to explain some of the clinical overlap between AD and FTLD-TDP, namely in memory deficits., (© 2017 S. Karger AG, Basel.)

Biologically formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 y ago [Kirschvink JL, Kobayashi-Kirschvink A, Woodford BJ (1992) Proc Natl Acad Sci USA 89(16):7683-7687]. Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. We used magnetic analyses and electron microscopy to identify the abundant presence in the brain of magnetite nanoparticles that are consistent with high-temperature formation, suggesting, therefore, an external, not internal, source. Comprising a separate nanoparticle population from the euhedral particles ascribed to endogenous sources, these brain magnetites are often found with other transition metal nanoparticles, and they display rounded crystal morphologies and fused surface textures, reflecting crystallization upon cooling from an initially heated, iron-bearing source material. Such high-temperature magnetite nanospheres are ubiquitous and abundant in airborne particulate matter pollution. They arise as combustion-derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidize upon airborne release. Those magnetite pollutant particles which are <∼200 nm in diameter can enter the brain directly via the olfactory bulb. Their presence proves that externally sourced iron-bearing nanoparticles, rather than their soluble compounds, can be transported directly into the brain, where they may pose hazard to human health., Competing Interests: The authors declare no conflict of interest.

Pathological accumulation of abnormally phosphorylated tau protein in astrocytes is a frequent, but poorly characterized feature of the aging brain. Its etiology is uncertain, but its presence is sufficiently ubiquitous to merit further characterization and classification, which may stimulate clinicopathological studies and research into its pathobiology. This paper aims to harmonize evaluation and nomenclature of aging-related tau astrogliopathy (ARTAG), a term that refers to a morphological spectrum of astroglial pathology detected by tau immunohistochemistry, especially with phosphorylation-dependent and 4R isoform-specific antibodies. ARTAG occurs mainly, but not exclusively, in individuals over 60 years of age. Tau-immunoreactive astrocytes in ARTAG include thorn-shaped astrocytes at the glia limitans and in white matter, as well as solitary or clustered astrocytes with perinuclear cytoplasmic tau immunoreactivity that extends into the astroglial processes as fine fibrillar or granular immunopositivity, typically in gray matter. Various forms of ARTAG may coexist in the same brain and might reflect different pathogenic processes. Based on morphology and anatomical distribution, ARTAG can be distinguished from primary tauopathies, but may be concurrent with primary tauopathies or other disorders. We recommend four steps for evaluation of ARTAG: (1) identification of five types based on the location of either morphologies of tau astrogliopathy: subpial, subependymal, perivascular, white matter, gray matter; (2) documentation of the regional involvement: medial temporal lobe, lobar (frontal, parietal, occipital, lateral temporal), subcortical, brainstem; (3) documentation of the severity of tau astrogliopathy; and (4) description of subregional involvement. Some types of ARTAG may underlie neurological symptoms; however, the clinical significance of ARTAG is currently uncertain and awaits further studies. The goal of this proposal is to raise awareness of astroglial tau pathology in the aged brain, facilitating communication among neuropathologists and researchers, and informing interpretation of clinical biomarkers and imaging studies that focus on tau-related indicators.

Aims: Frontotemporal lobar degeneration (FTLD) and motor neurone disease are linked by the possession of a hexanucleotide repeat expansion in C9ORF72, and both show neuronal cytoplasmic inclusions within cerebellar and hippocampal neurones which are TDP-43 negative but immunoreactive for p62 and dipeptide repeat proteins (DPR), these being generated by a non-ATG RAN translation of the expanded region of the gene., Methods: Twenty-two cases of FTLD from Newcastle were analysed for an expansion in C9ORF72 by repeat primed PCR and Southern blot. Detailed case note analysis was performed, and blinded retrospective clinical impressions were achieved by review of clinical histories. Sections from all major brain regions were immunostained for TDP-43, p62 and DPR. The extent of TDP-43 and DPR pathology in expansion bearers was compared with that in 13 other previously identified cases from the Manchester Brain Bank with established disease., Results: Three Newcastle patients bearing an expansion in C9ORF72 were identified. These three patients died prematurely, two from bronchopneumonia within 10 months and 3 years of onset, and one from myocardial infarction 3 years after onset. In all three, DPR were plentiful throughout all cerebral cortical regions, hippocampus and cerebellum, but TDP-43 pathological changes were sparse. The severity of DPR pathological changes in these three patients was similar to that in the Manchester series, although the extent of TDP-43 pathology was significantly less., Conclusion: Widespread accumulation of DPR within nerve cells may occur much earlier than that of TDP-43 in patients with FTLD bearing expansion in C9ORF72., (© 2014 British Neuropathological Society.)

α-Synuclein (α-syn), a small protein that has the intrinsic propensity to aggregate, is implicated in several neurodegenerative diseases including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), which are collectively known as synucleinopathies. Genetic, pathological, biochemical, and animal modeling studies provided compelling evidence that α-syn aggregation plays a key role in the pathogenesis of PD and related synucleinopathies. It is therefore of utmost importance to develop reliable tools that can detect the aggregated forms of α-syn. We describe here the generation and characterization of six novel conformation-specific monoclonal antibodies that recognize specifically α-syn aggregates but not the soluble, monomeric form of the protein. The antibodies described herein did not recognize monomers or fibrils generated from other amyloidogenic proteins including β-syn, γ-syn, β-amyloid, tau protein, islet amyloid polypeptide and ABri. Interestingly, the antibodies did not react to overlapping linear peptides spanning the entire sequence of α-syn, confirming further that they only detect α-syn aggregates. In immunohistochemical studies, the new conformation-specific monoclonal antibodies showed underappreciated small micro-aggregates and very thin neurites in PD and DLB cases that were not observed with generic pan antibodies that recognize linear epitope. Furthermore, employing one of our conformation-specific antibodies in a sandwich based ELISA, we observed an increase in levels of α-syn oligomers in brain lysates from DLB compared to Alzheimer's disease and control samples. Therefore, the conformation-specific antibodies portrayed herein represent useful tools for research, biomarkers development, diagnosis and even immunotherapy for PD and related pathologies., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Our objective was to compare the clinical and pathological characteristics of frontotemporal dementia patients with MAPT, GRN and C9orf72 gene mutations. We carried out a cross-sectional comparative study of 74 gene-positive patients (15 MAPT, 17 GRN and 42 C9orf72). Thirty had post mortem pathological data permitting clinico-pathological correlation. MAPT patients were younger than other groups, and showed more frequent behavioural disinhibition, repetitive and stereotyped behaviours, semantic impairment and temporal predominance of atrophy. GRN patients were older at death and more likely to present with non-fluent aphasia. C9orf72 patients alone showed a co-occurrence of ALS. They showed more psychotic symptoms and irrational behaviour, yet were more often reported clinically as socially appropriate and warm. They showed less dietary change than other groups. C9orf72 patients with and without ALS differed only in frequency of psychosis. Greater clinical overlap was observed between GRN and C9orf72 compared to MAPT cases. MAPT cases had tau and GRN and C9orf72, with one exception, TDP-43 pathology. Non-fluent aphasia was linked to TDP subtype A in both GRN and C9orf72 cases and ALS with subtype B. In conclusion, the findings reinforce clinical heterogeneity in FTD and strengthen evidence that genotype influences clinical presentation. Clinical features may inform targeted genetic testing.

Aims: Pathological heterogeneity within patients with frontotemporal lobar degeneration (FTLD) in general precludes the accurate assignment of diagnostic subtype in life. The aim of this study was to assess the extent of microglial cell activation in FTLD in order to determine whether it might be possible to employ this as a diagnostic marker in vivo using PET ligand [11C](R)-PK11195 in order to differentiate cases of FTLD according to histological subtype., Methods: The distribution and extent of microglial cell activation was assessed semi-quantitatively in cortical grey and subcortical white matter of CD68 immunostained sections of frontal and temporal cortex from 78 pathologically confirmed cases of FTLD, 13 of Alzheimer's disease (AD) and 13 controls., Results: Significantly higher levels of microglial cell activation than controls occurred in all four regions in FTLD, and in three of the four regions in AD. Microglial activation was greater in frontal subcortical white matter in FTLD than AD, whereas it was higher in temporal cortical grey matter in AD than FTLD. Microglial cell activation was significantly higher in temporal subcortical white matter in FTLD-MAPT than in other genetic (GRN, C9ORF72) or non-genetic forms of FTLD., Conclusions: The present study suggests that high levels of microglial cell involvement in temporal lobe (subcortical white matter) might serve as a marker of inherited FTLD associated with intronic mutations in MAPT, with a relatively intense signal in this region in PET studies using [11C](R)-PK11195 as microglial cell marker could indicate the presence of MAPT mutation in vivo., (© 2013 British Neuropathological Society.)

A hexanucleotide (GGGGCC) expansion in C9ORF72 gene is the most common genetic change seen in familial Frontotemporal Lobar Degeneration (FTLD) and familial Motor Neurone Disease (MND). Pathologically, expansion bearers show characteristic p62 positive, TDP-43 negative inclusion bodies within cerebellar and hippocampal neurons which also contain dipeptide repeat proteins (DPR) formed from sense and antisense RAN (repeat associated non ATG-initiated) translation of the expanded repeat region itself. 'Inappropriate' formation, and aggregation, of DPR might therefore confer neurotoxicity and influence clinical phenotype. Consequently, we compared the topographic brain distribution of DPR in 8 patients with Frontotemporal dementia (FTD), 6 with FTD + MND and 7 with MND alone (all 21 patients bearing expansions in C9ORF72) using a polyclonal antibody to poly-GA, and related this to the extent of TDP-43 pathology in key regions of cerebral cortex and hippocampus. There were no significant differences in either the pattern or severity of brain distribution of DPR between FTD, FTD + MND and MND groups, nor was there any relationship between the distribution of DPR and TDP-43 pathologies in expansion bearers. Likewise, there were no significant differences in the extent of TDP-43 pathology between FTLD patients bearing an expansion in C9ORF72 and non-bearers of the expansion. There were no association between the extent of DPR pathology and TMEM106B or APOE genotypes. However, there was a negative correlation between the extent of DPR pathology and age at onset. Present findings therefore suggest that although the presence and topographic distribution of DPR may be of diagnostic relevance in patients bearing expansion in C9ORF72 this has no bearing on the determination of clinical phenotype. Because TDP-43 pathologies are similar in bearers and non-bearers of the expansion, the expansion may act as a major genetic risk factor for FTLD and MND by rendering the brain highly vulnerable to those very same factors which generate FTLD and MND in sporadic disease.

Background: Cases of Frontotemporal Lobar Degeneration (FTLD) and Motor Neurone Disease (MND) associated with expansions in C9ORF72 gene are characterised pathologically by the presence of TDP-43 negative, but p62 positive, inclusions in granule cells of the cerebellum and in cells of dentate gyrus and area CA4 of the hippocampus., Results: We screened 84 cases of pathologically confirmed FTLD and 23 cases of MND for the presence of p62 positive inclusions in these three brain regions, and identified 13 positive cases of FTLD and 3 of MND. All cases demonstrated expansions in C9ORF72 by Southern blotting where frozen tissues were available. The p62 positive inclusions in both cerebellum and hippocampus were immunostained by antibodies to dipeptide repeat proteins (DPR), poly Gly-Ala (poly-GA), poly Gly-Pro (poly-GP) and poly Gly-Arg (poly-GR), these arising from a putative non-ATG initiated (RAN) sense translation of the GGGGCC expansion. There was also some slight, but variable, immunostaining with poly-AP antibody implying some antisense translation might also occur, though the relative paucity of immunostaining could reflect poor antigen avidity on the part of the antisense antibodies. Of the FTLD cases with DPR, 6 showed TDP-43 type A and 6 had TDP-43 type B histology; one had FTLD-tau with the pathology of corticobasal degeneration. There were no qualitative or quantitative differences in the pattern of immunostaining with antibodies to DPR, or p62, proteins between TDP-43 type A and type B cases. Ratings for frequency of inclusions immunostained by these poly-GA, poly-GP and poly-GR antibodies broadly correlated with those for immunolabelled by p62 antibody in all three regions., Conclusion: We conclude that DPR are a major component of p62 positive inclusions in FTLD and MND.

Background: Intracytoplasmic inclusions composed of filamentous tau proteins are defining characteristics of neurodegenerative tauopathies, but it remains unclear why different tau isoforms accumulate in different diseases and how they induce abnormal filamentous structures and pathologies. Two tau isoform-specific antibodies, RD3 and RD4, are widely used for immunohistochemical and biochemical studies of tau species in diseased brains., Results: Here, we show that extensive irreversible post-translational deamidation takes place at asparagine residue 279 (N279) in the RD4 epitope of tau in Alzheimer's disease (AD), but not corticobasal degeneration (CBD) or progressive supranuclear palsy (PSP), and this modification abrogates the immunoreactivity to RD4. An antiserum raised against deamidated RD4 peptide specifically recognized 4R tau isoforms, regardless of deamidation, and strongly stained tau in AD brain. We also found that mutant tau with N279D substitution showed reduced ability to bind to microtubules and to promote microtubule assembly., Conclusion: The biochemical and structural differences of tau in AD from that in 4R tauopathies found in this study may therefore have implications for prion-like propagation of tau.

TDP-43 is the major component protein of ubiquitin-positive inclusions in brains of patients with frontotemporal lobar degeneration (FTLD-TDP) or amyotrophic lateral sclerosis (ALS). Here, we report the characterization of prion-like properties of aggregated TDP-43 prepared from diseased brains. When insoluble TDP-43 from ALS or FTLD-TDP brains was introduced as seeds into SH-SY5Y cells expressing TDP-43, phosphorylated and ubiquitinated TDP-43 was aggregated in a self-templating manner. Immunoblot analyses revealed that the C-terminal fragments of insoluble TDP-43 characteristic of each disease type acted as seeds, inducing seed-dependent aggregation of TDP-43 in these cells. The seeding ability of insoluble TDP-43 was unaffected by proteinase treatment but was abrogated by formic acid. One subtype of TDP-43 aggregate was resistant to boiling treatment. The insoluble fraction from cells harboring TDP-43 aggregates could also trigger intracellular TDP-43 aggregation. These results indicate that insoluble TDP-43 has prion-like properties that may play a role in the progression of TDP-43 proteinopathy., (Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Objective: Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder, caused by a CAG/polyglutamine repeat expansion, which is associated with a dysregulation of histone function and an impairment of protein transcription. Histone deacetylase (HDAC) inhibitors, such as vorinostat (SAHA), have shown promise as therapeutic agents. However, there have been few studies on the expression of HDACs and acetylated core histones (AcHs) in either normal animals or humans, or in HD patients or HD animal models. Therefore, we investigated the expression of HDACs and AcHs in HD brain by immunohistochemistry, and have compared findings with elderly control subjects and patients with frontotemporal lobar degeneration (FTLD) to determine whether any observed changes were specific for HD., Results and Conclusion: we show specific and significant losses of AcH2A, AcH2B, AcH3 and AcH4 expression from cells in the caudate nucleus and Purkinje cells of the cerebellum in HD compared to patients with FTLD and control subjects, while the level of HDAC 5 was increased in these cells., (Copyright © 2013 Elsevier B.V. All rights reserved.)

α-Synuclein is the major component of filamentous inclusions that constitute the defining characteristic of neurodegenerative α-synucleinopathies. However, the molecular mechanisms underlying α-synuclein accumulation and spread are unclear. Here we show that intracerebral injections of sarkosyl-insoluble α-synuclein from brains of patients with dementia with Lewy bodies induced hyperphosphorylated α-synuclein pathology in wild-type mice. Furthermore, injection of fibrils of recombinant human and mouse α-synuclein efficiently induced similar α-synuclein pathologies in wild-type mice. C57BL/6J mice injected with α-synuclein fibrils developed abundant Lewy body/Lewy neurite-like pathology, whereas mice injected with soluble α-synuclein did not. Immunoblot analysis demonstrated that endogenous mouse α-synuclein started to accumulate 3 months after inoculation, while injected human α-synuclein fibrils disappeared in about a week. These results indicate that α-synuclein fibrils have prion-like properties and inoculation into wild-type brain induces α-synuclein pathology in vivo. This is a new mouse model of sporadic α-synucleinopathy and should be useful for elucidating progression mechanisms and evaluating disease-modifying therapy.

Frontotemporal lobar degeneration (FTLD) is clinically, pathologically and genetically heterogeneous. Three major proteins are implicated in its pathogenesis. About half of cases are characterized by depositions of the microtubule associated protein, tau (FTLD-tau). In most of the remaining cases, deposits of the transactive response (TAR) DNA-binding protein with Mw of 43 kDa, known as TDP-43 (FTLD-TDP), are seen. Lastly, about 5-10 % of cases are characterized by abnormal accumulations of a third protein, fused in sarcoma (FTLD-FUS). Depending on the protein concerned, the signature accumulations can take the form of inclusion bodies (neuronal cytoplasmic inclusions and neuronal intranuclear inclusions) or dystrophic neurites, in the cerebral cortex, hippocampus and subcortex. In some instances, glial cells are also affected by inclusion body formation. In motor neurone disease (MND), TDP-43 or FUS inclusions can present within motor neurons of the brain stem and spinal cord. This present paper attempts to critically examine the role of such proteins in the pathogenesis of FTLD and MND as to whether they might exert a direct pathogenetic effect (gain of function), or simply act as relatively innocent witnesses to a more fundamental loss of function effect. We conclude that although there is strong evidence for both gain and loss of function effects in respect of each of the proteins concerned, in reality, it is likely that each is a single face of either side of the coin, and that both will play separate, though complementary, roles in driving the damage which ultimately leads to the downfall of neurons and clinical expression of disease.

Objective: To determine whether cases of frontotemporal lobar degeneration (FTLD) do exist in elderly individuals and have clinical and neuropathological features distinct from those with presenile onset., Design: Retrospective matched cohort study., Setting: Regional Neuroscience Centre, North East England., Patients: We compared clinicopathological features of 11 cases of FTLD in elderly individuals with 19 cases of presenile-onset FTLD., Results: Retrospective case note analysis showed that most elderly patients with FTLD had behavioral features consistent with orbitofrontal and basofrontal involvement, similar to presenile-onset FTLD, though symptomatic memory loss was present in 91% (10 of 11) of elderly patients with FTLD compared with only 36% (7 of 19) of patients with presenile-onset FTLD. Neuropathologically, the group of elderly patients with FTLD comprised 7 with FTLD–TDP-43, 1 with ubiquitin-positive FTLD, 2 with FTLD-tau/Pick disease, and 1 with FTLD-tau/neurofibrillary tangle–predominant dementia with TDP-43, a composition similar to presenile-onset FTLD. However, hippocampal sclerosis was more common in elderly patients with FTLD than patients with presenile-onset FTLD (82% vs 37%) and more severe in elderly patients with FTLD (P < .05). By contrast, severe atrophy of the frontal and temporal lobes was less common in elderly patients with FTLD (frontal: 45%; temporal: 27%) than patients with presenile-onset FTLD (frontal: 63%; temporal: 78%). Elderly patients with FTLD represented 3.2% of all elderly patients with dementia autopsied at Newcastle General Hospital., Conclusions: Frontotemporal lobar degeneration in elderly patients does exist as a separate entity from presenile-onset FTLD. Its main features include (1) clinically frequent memory loss and behavioral change predominating over language and semantic dysfunction and (2) neuropathologically prominent hippocampal sclerosis but less pronounced cortical lobar atrophy. Clinically, FTLD in elderly patients is underrecognized and should be considered in the elderly subjects presenting with an “atypical Alzheimer disease” phenotype.

Clinicopathologic correlation studies are critically important for the field of Alzheimer disease (AD) research. Studies on human subjects with autopsy confirmation entail numerous potential biases that affect both their general applicability and the validity of the correlations. Many sources of data variability can weaken the apparent correlation between cognitive status and AD neuropathologic changes. Indeed, most persons in advanced old age have significant non-AD brain lesions that may alter cognition independently of AD. Worldwide research efforts have evaluated thousands of human subjects to assess the causes of cognitive impairment in the elderly, and these studies have been interpreted in different ways. We review the literature focusing on the correlation of AD neuropathologic changes (i.e. β-amyloid plaques and neurofibrillary tangles) with cognitive impairment. We discuss the various patterns of brain changes that have been observed in elderly individuals to provide a perspective for understanding AD clinicopathologic correlation and conclude that evidence from many independent research centers strongly supports the existence of a specific disease, as defined by the presence of Aβ plaques and neurofibrillary tangles. Although Aβ plaques may play a key role in AD pathogenesis, the severity of cognitive impairment correlates best with the burden of neocortical neurofibrillary tangles.

Frontotemporal lobar degeneration (FTLD) is the umbrella term encompassing a heterogeneous group of pathological disorders. With recent discoveries, the FTLDs have been show to classify nicely into three main groups based on the major protein deposited in the brain: FTLD-tau, FTLD-TDP and FTLD-FUS. These pathological groups, and their specific pathologies, underlie a number of well-defined clinical syndromes, including three frontotemporal dementia (FTD) variants [behavioral variant frontotemporal dementia (bvFTD), progressive non-fluent aphasia, and semantic dementia (SD)], progressive supranuclear palsy syndrome (PSPS) and corticobasal syndrome (CBS). Understanding the neuropathological background of the phenotypic variability in FTD, PSPS and CBS requires large clinicopathological studies. We review current knowledge on the relationship between the FTLD pathologies and clinical syndromes, and pool data from a number of large clinicopathological studies that collectively provide data on 544 cases. Strong relationships were identified as follows: FTD with motor neuron disease and FTLD-TDP; SD and FTLD-TDP; PSPS and FTLD-tau; and CBS and FTLD-tau. However, the relationship between some of these clinical diagnoses and specific pathologies is not so clear cut. In addition, the clinical diagnosis of bvFTD does not have a strong relationship to any FTLD subtype or specific pathology and therefore remains a diagnostic challenge. Some evidence suggests improved clinicopathological association of bvFTD by further refining clinical characteristics. Unlike FTLD-tau and FTLD-TDP, FTLD-FUS has been less well characterized, with only 69 cases reported. However, there appears to be some associations between clinical phenotypes and FTLD-FUS pathologies. Clinical diagnosis is therefore promising in predicting molecular pathology.

It has been reported that the development of TDP-43 pathology in cases of Lewy body disease (LBD) might be associated with the severity of tau pathology. However, the impact of α-synuclein pathology on TDP-43 accumulation in LBD remains unclear. To clarify whether α-synuclein pathology has an effect on TDP-43 accumulation, independent of tau pathology, we examined by immunohistochemistry 56 cases of LBD using a phosphorylation-dependent TDP-43 antibody. The frequency of TDP-43 pathology in all LBD cases was 18% (10/56). In 37 LBD cases with no or low tau burden (LBD-Ltau; Braak NFT stages 0-II), the frequency of TDP-43 pathology was 19% (7/37). The frequency of TDP-43 pathology in diffuse neocortical type LBD-Ltau cases was 36% (4/11), which was higher than those in limbic and brain stem-predominant types (11-14%). The amygdala and entorhinal cortex were the most frequently affected sites of TDP-43 pathology in LBD-Ltau cases. In LBD-Ltau cases, the proportion of diffuse neocortical type LBD was higher in the TDP-43-positive cases, than that in TDP-43-negative cases (57 vs. 23%). In all LBD cases, α-synuclein pathology in the temporal cortex was significantly more severe in TDP-43-positive cases, and significantly correlated with the severity of TDP-43 pathology in the amygdala. In a multivariate model, the presence of severe α-synuclein pathology was significantly associated with the development of TDP-43 pathology independent of age at death and tau pathology. In the amygdala, TDP-43 was often colocalized with α-synuclein or tau. Given these findings, we suggest that α-synuclein pathology is associated with TDP-43 accumulation in LBD cases.

In the present study, we have correlated plasma TDP-43 levels, as measured by ELISA, with the presence of TDP-43 pathological changes in the brains of 28 patients with frontotemporal lobar degeneration (FTLD) (14 with FTLD-TDP and 14 with FTLD-tau) and 24 patients with pathologically confirmed AD (8 with, and 16 without, TDP-43 pathological changes). Western blotting revealed full-length TDP-43, including a phosphorylated form, and a phosphorylated C-terminal fragment, in all samples examined. Both ELISA and immunohistochemistry were performed using phospho-dependent and phospho-independent TDP-43 antibodies for detection of phosphorylated and total TDP-43, respectively. Over all 52 cases, plasma levels of TDP-43, and scores of brain TDP-43 pathology, determined using TDP-43 phospho-dependent antibody correlated with the equivalent measure determined using the TDP phospho-independent antibody. In FTLD, but not AD, TDP-43 plasma levels correlated significantly with the pathology score when using the TDP-43 phospho-dependent antibody, but a similar correlation was not seen in either FTLD or AD using the TDP-43 phospho-independent antibody. With the TDP-43 phospho-independent antibody, there were no significant differences in median plasma TDP-43 levels between FTLD, or AD, patients with or without TDP-43 pathology. Using TDP-43 phospho-dependent antibody, median plasma TDP-43 levels were greater in patients with, than in those without, TDP-43 pathology for FTLD patients, though not significantly so, but not for AD patients. Present assays for TDP-43 do not differentiate between FTLD, or AD, patients with or without TDP-43 pathological changes in their brains. However, the levels of phosphorylated TDP-43 in plasma do correlate with the extent of TDP-43 brain pathology in FTLD, and therefore might be a useful surrogate marker for tracking changes in TDP-43 brain pathology during the course of this disease.

A number of neurodegenerative diseases including Parkinson's disease, dementia with Lewy bodies (DLB) and multiple system atrophy are characterized by the formation and intraneuronal accumulation of fibrillar aggregates of alpha-synuclein (alpha-syn) protein in affected brain regions. These and other findings suggest that the accumulation of alpha-syn in the brain plays an important role in the pathogenesis of these diseases. However, more recently it has been reported that early amyloid aggregates or 'soluble oligomers' are the pathogenic species that lead to neurodegeneration and neuronal cell death rather than the later 'mature fibrils'. In this study, we investigated the presence of alpha-syn oligomers in brain lysates prepared from frozen post-mortem brains of normal, Alzheimer's disease and DLB patients. The brain extracts were subjected to high speed centrifugation, to remove insoluble alpha-syn aggregates, followed by specific detection of soluble oligomers in the supernatants by employing FILA-1, an antibody that specifically binds to alpha-syn aggregates, but not to alpha-syn monomers, or to tau or beta-amyloid aggregates. Using this novel enzyme-linked immunosorbent assay (ELISA) method to quantify the amounts of alpha-syn oligomers in the brain extracts, our data clearly show an increase in the levels of soluble oligomers of alpha-syn in the DLB brains compared to those with Alzheimer's disease and the controls (P < 0.0001). Our findings provide strong evidence to support the contention that elevated soluble oligomers of alpha-syn are involved in the pathogenesis of DLB. Furthermore, these findings establish FILA-1 as a very sensitive tool for the detection of oligomeric forms of alpha-syn in human brain lysates.

Autopsy studies have shown that about 55% of patients with frontotemporal lobar degeneration (FTLD) and 25% of patients with Alzheimer's disease (AD) harbour TDP-43 immunoreactive pathological changes in their brains. Using ELISA, we investigated whether we could detect the presence, or increased amounts, of TDP-43 in plasma of patients with FTLD and AD compared to normal control subjects. We detected elevated levels of TDP-43 protein in plasma of 46% patients with FTLD with clinical frontotemporal dementia (FTD) and 22% patients with AD, compared to 8% of control subjects. The proportions of patients with FTD and AD showing raised plasma TDP-43 levels correspond closely to those proportions known from autopsy studies to contain TDP-43 pathological changes in their brains. Raised TDP-43 plasma levels may thereby index TDP-43 pathology within the brain. Plasma TDP-43 levels may be a biomarker that can provide a laboratory test capable of identifying the presence of TDP-43 brain pathology in neurodegenerative disease during life. It may help to distinguish those cases of FTLD with ubiquitin/TDP-43 pathology in their brains from those with tauopathy. As a predictive test, plasma TDP-43 level may have great practical value in directing therapeutic strategies aimed at preventing or removing tau or TDP-43 pathological changes from the brain in FTLD and AD.

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are both characterized by the formation and intraneuronal accumulation of fibrillar aggregates of alpha-synuclein (alpha-syn) protein in affected brain regions. alpha-Syn has biochemical properties and a structural motif characteristic of fatty acid binding proteins. Using the fatty acid binding resin Lipidex-1000, we investigated the capture of alpha-, beta-, and gamma-syn proteins as lipid-associated proteins from normal and DLB brain lysates, and from normal human cerebrospinal fluid (CSF). These were eluted from Lipidex-1000 and analyzed by SDS-NuPAGE followed by Western blotting. Using this methodology, we have been able to extract full-length and truncated forms of alpha-syn from brain lysates. We also extracted low levels of beta-syn from DLB brains, but failed to extract any gamma-syn. We were able to capture only full-length monomeric alpha-syn from normal human CSF. Our data confirm the fatty acid binding properties of alpha-syn, and to a lesser extent beta-syn, but suggest that gamma-syn does not share this same characteristic.

Objectives: To examine the association between the angiotensin-converting enzyme (ACE) deletion/insertion (D/I) polymorphism and white matter hyperintensities (WMHs) in patients with dementia., Design: Observational pilot study with adjustment for potential confounders using analysis of covariance., Setting: Secondary care old-age psychiatry services in greater Manchester, United Kingdom., Participants: Ninety-seven patients with dementia: 49 with Alzheimer's disease (AD, National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association criteria) and 48 with vascular dementia (VaD, National Institute of Neurological Disorders and Stroke/Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria)., Measurements: The ACE D/I polymorphism, WMHs (deep WMHs (DWMHs) and periventricular hyperintensities (PVHs)) on T2-weighted magnetic resonance imaging, and potential cardiovascular confounders., Results: The D/D polymorphism of the ACE genotype was associated with severity of DWMH (P = .005) but not PVH (P = .34), corrected for age, cardiovascular risk factors, and type of dementia. Post hoc analyses were limited by statistical power but suggested an interaction with the apolipoprotein E epsilon4 allele., Conclusion: The results support previous observations that genetic factors influence the development of WMHs in dementia. The involvement of the ACE D/I polymorphism in the pathogenesis of DWMHs in dementia (AD and VaD), by a mechanism that is independent of its association with cardiovascular risk factors, should be confirmed in a large population-based sample.

The pathological distinctions between the various clinical and pathological manifestations of frontotemporal lobar degeneration (FTLD) remain unclear. Using monoclonal antibodies specific for 3- and 4-repeat isoforms of the microtubule associated protein, tau (3R- and 4R-tau), we have performed an immunohistochemical study of the tau pathology present in 14 cases of sporadic forms of FTLD, 12 cases with Pick bodies and two cases without and in 27 cases of familial FTLD associated with 12 different mutations in the tau gene (MAPT), five cases with Pick bodies and 22 cases without. In all 12 cases of sporadic FTLD where Pick bodies were present, these contained only 3R-tau isoforms. Clinically, ten of these cases had frontotemporal dementia and two had progressive apraxia. Only 3R-tau isoforms were present in Pick bodies in those patients with familial FTLD associated with L266V, Q336R, E342V, K369I or G389R MAPT mutations. Patients with familial FTLD associated with exon 10 N279K, N296H or +16 splice site mutations showed tau pathology characterised by neuronal neurofibrillary tangles (NFT) and glial cell tangles that contained only 4R-tau isoforms, as did the NFT in P301L MAPT mutation. With the R406W mutation, NFT contained both 3R- and 4R-tau isoforms. We also observed two patients with sporadic FTLD, but without Pick bodies, in whom the tau pathology comprised only of 4R-tau isoforms. We have therefore shown by immunohistochemistry that different specific tau isoform compositions underlie the various kinds of tau pathology present in sporadic and familial FTLD. The use of such tau isoform specific antibodies may refine pathological criteria underpinning FTLD.

Genome scans in sporadic Alzheimer's disease (AD) have revealed a possible susceptibility locus on chromosome 12. The low density lipoprotein receptor related protein (LRP1) gene lies within this area of linkage. Eighteen previous AD case-control studies have investigated the C766T polymorphism in LRP1 with conflicting results, including a protective effect on AD of the T allele, an increased susceptibility towards AD with both the C and T alleles, or no association at all. We have now performed a case-control study based on a large UK cohort of 477 AD patients and 466 matched controls, and have included these data, with those drawn from the 18 previous studies, into in a meta-analysis of 4668 AD patients and 4473 controls. We find no evidence for influence on the risk for AD in either our own present cohort or in the combined data set. Furthermore, we investigated whether the C766T polymorphism might modify the clinical and pathological phenotype in our cohort. We found no association with AD when the cohort was stratified into those with early (<65 years) or late (>65 years) onset, or when split into Apolipoprotein E (APOE) epsilon4 bearers and epsilon4 non-bearers. In addition, the C766T polymorphism was shown not to influence the age onset of AD. In a separate autopsy-confirmed cohort of 130 AD cases, no association with genotype or allele was observed for tissue levels of beta-amyloid 40, beta-amyloid 42, total beta-amyloid, pathological tau proteins, microglial cells or extent of astrocytic activity. Therefore, in this present study, we find no evidence for the involvement of this polymorphism either in increasing the susceptibility to AD, or by acting as a phenotypic modifier.

Pathological tau accumulates in the brain in tauopathies such as Alzheimer's disease, Pick's disease, progressive supranuclear palsy and corticobasal degeneration, and forms amyloid-like filaments incorporating various post-translational modifications (PTMs). Cryo-electron microscopic (cryo-EM) studies have demonstrated that tau filaments extracted from tauopathy brains are characteristic of the disease and share a common fold(s) in the same disease group. Furthermore, the tau PTM profile changes during tau pathology formation and disease progression, and disease-specific PTMs are detected in and around the filament core. In addition, templated seeding has been suggested to trigger pathological tau amplification and spreading in vitro and in vivo , although the molecular mechanisms are not fully understood. Recently, we reported that the cryo-EM structures of tau protofilaments in SH-SY5Y cells seeded with patient-derived tau filaments show a core structure(s) resembling that of the original seeds. Here, we investigated PTMs of tau filaments accumulated in the seeded cells by liquid chromatography/tandem mass spectrometry and compared them with the PTMs of patient-derived tau filaments. Examination of insoluble tau extracted from SH-SY5Y cells showed that numerous phosphorylation, deamidation and oxidation sites detected in the fuzzy coat in the original seeds were well reproduced in SH-SY5Y cells. Moreover, templated tau filament formation preceded both truncation of the N-/C-terminals of tau and PTMs in and around the filament core, indicating these PTMs may predominantly be introduced after the degradation of the fuzzy coat. [ABSTRACT FROM AUTHOR]

Tauopathies are a subset of neurodegenerative diseases characterized by abnormal tau inclusions. Specifically, three-repeat tau and four-repeat tau in Alzheimer's disease, three-repeat tau in Pick's disease (PiD) and four-repeat tau in progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) form amyloid-like fibrous structures that accumulate in neurons and/or glial cells. Amplification and cell-to-cell transmission of abnormal tau based on the prion hypothesis are believed to explain the onset and progression of tauopathies. Recent studies support not only the self-propagation of abnormal tau, but also the presence of conformationally distinct tau aggregates, namely tau strains. Cryogenic electron microscopy analyses of patient-derived tau filaments have revealed disease-specific ordered tau structures. However, it remains unclear whether the ultrastructural and biochemical properties of tau strains are inherited during the amplification of abnormal tau in the brain. In this study, we investigated template-dependent amplification of tau aggregates using a cellular model of seeded aggregation. Tau strains extracted from human tauopathies caused strain-dependent accumulation of insoluble filamentous tau in SH-SY5Y cells. The seeding activity towards full-length four-repeat tau substrate was highest in CBD-tau seeds, followed by PSP-tau and Alzheimer's disease (AD)-tau seeds, while AD-tau seeds showed higher seeding activity than PiD-tau seeds towards three-repeat tau substrate. Abnormal tau amplified in cells inherited the ultrastructural and biochemical properties of the original seeds. These results strongly suggest that the structural differences of patient-derived tau strains underlie the diversity of tauopathies, and that seeded aggregation and filament formation mimicking the pathogenesis of sporadic tauopathy can be reproduced in cultured cells. Our results indicate that the disease-specific conformation of tau aggregates determines the tau isoform substrate that is recruited for templated amplification, and also influences the prion-like seeding activity. [ABSTRACT FROM AUTHOR]

Inflammatory and immune responses are involved in the pathogenesis of Alzheimer''s disease (AD). Interleukin-6 (IL-6), an inflammatory cytokine, is thought to play a role in neurodegeneration of the central nervous system and has been associated with increased amyloid precursor protein expression in vitro and greater cognitive decline. Previously a C-174G polymorphism in the promoter of IL-6, which influences expression in vitro, has been found associated in some studies but not all. We investigated this polymorphism in a large independent UK sample of AD cases (n=356) and controls (n=434) but found no association. We extended the study to genotype/phenotype correlations but found no correlation with age of onset (n=338), brain amyloid load (n=126) or Tau load (n=101), brain microglial cell load (n=65) or brain reactive astrocytes (n=127). Our data do not support a pathogenic role in AD for the C-174G polymorphism in isolation. [Copyright &y& Elsevier]