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Background: While most patients with Alzheimer's disease (AD) present with memory complaints, 30% of patients with early disease onset present with non-amnestic symptoms. This atypical presentation is thought to be caused by a different spreading of neurofibrillary tangles (NFT) than originally proposed by Braak and Braak. Recent studies suggest a prominent role for neuroinflammation in the spreading of tau pathology., Methods: We aimed to explore whether an atypical spreading of pathology in AD is associated with an atypical distribution of neuroinflammation. Typical and atypical AD cases were selected based on both NFT distribution and amnestic or non-amnestic clinical presentation. Immunohistochemistry was performed on the temporal pole and superior parietal lobe of 10 typical and 9 atypical AD cases. The presence of amyloid-beta (N-terminal; IC16), pTau (AT8), reactive astrocytes (GFAP), microglia (Iba1, CD68, and HLA-DP/DQ/DR), and complement factors (C1q, C3d, C4b, and C5b-9) was quantified by image analysis. Differences in lobar distribution patterns of immunoreactivity were statistically assessed using a linear mixed model., Results: We found a temporal dominant distribution for amyloid-beta, GFAP, and Iba1 in both typical and atypical AD. Distribution of pTau, CD68, HLA-DP/DQ/DR, C3d, and C4b differed between AD variants. Typical AD cases showed a temporal dominant distribution of these markers, whereas atypical AD cases showed a parietal dominant distribution. Interestingly, when quantifying for the number of amyloid-beta plaques instead of stained surface area, atypical AD cases differed in distribution pattern from typical AD cases. Remarkably, plaque morphology and localization of neuroinflammation within the plaques was different between the two phenotypes., Conclusions: Our data show a different localization of neuroinflammatory markers and amyloid-beta plaques between AD phenotypes. In addition, these markers reflect the atypical distribution of tau pathology in atypical AD, suggesting that neuroinflammation might be a crucial link between amyloid-beta deposits, tau pathology, and clinical symptoms.

Background: Progressive supranuclear palsy (PSP) with a frontal presentation, characterized by cognitive deficits and behavioral changes, has been recognized as an early clinical picture, distinct from the classical so-called Richardson and parkinsonism presentations. The midcingulate cortex is associated with executive and attention tasks and has consistently been found to be impaired in imaging studies of patients with PSP. The aim of the present study was to determine alterations in neurotransmission underlying the pathophysiology of PSP, as well as their significance for clinically identifiable PSP subgroups., Methods: In vitro receptor autoradiography was used to quantify densities of 20 different receptors in the caudate nucleus and midcingulate area 24' of patients with PSP (n = 16) and age- and sex-matched control subjects (n = 14)., Results: Densities of γ-aminobutyric acid type B, peripheral benzodiazepine, serotonin receptor type 2, and N-methyl-D-aspartate receptors were significantly higher in area 24' of patients with PSP, where tau impairment was stronger than in the caudate nucleus. Kainate and nicotinic cholinergic receptor densities were significantly lower, and adenosine receptor type 1 (A 1 ) receptors significantly higher, in the caudate nucleus of patients with PSP. Receptor fingerprints also segregated PSP subgroups when clinical parameters such as occurrence of frontal presentation and tau pathology severity were taken into consideration., Conclusions: We demonstrate, for the first time to our knowledge, that kainate and A 1 receptors are altered in PSP and that clinically identifiable PSP subgroups differ at the neurochemical level. Numerous receptors were altered in the midcingulate cortex, further suggesting that it may prove to be a key region in PSP. Finally, we add to the evidence that nondopaminergic systems play a role in the pathophysiology of PSP, thus highlighting potential novel treatment strategies.

Pathological accumulation of intermediate filaments can be observed in neurodegenerative disorders, such as Alzheimer's disease, frontotemporal dementia and Parkinson's disease, and is also characteristic of neuronal intermediate filament inclusion disease. Intermediate filaments type IV include three neurofilament proteins (light, medium and heavy molecular weight neurofilament subunits) and α-internexin. The phosphorylation of intermediate filament proteins contributes to axonal growth, and is regulated by protein kinase A. Here we describe a family with a novel late-onset neurodegenerative disorder presenting with dementia and/or parkinsonism in 12 affected individuals. The disorder is characterized by a unique neuropathological phenotype displaying abundant neuronal inclusions by haematoxylin and eosin staining throughout the brain with immunoreactivity for intermediate filaments. Combining linkage analysis, exome sequencing and proteomics analysis, we identified a heterozygous c.149T>G (p.Leu50Arg) missense mutation in the gene encoding the protein kinase A type I-beta regulatory subunit (PRKAR1B). The pathogenicity of the mutation is supported by segregation in the family, absence in variant databases, and the specific accumulation of PRKAR1B in the inclusions in our cases associated with a specific biochemical pattern of PRKAR1B. Screening of PRKAR1B in 138 patients with Parkinson's disease and 56 patients with frontotemporal dementia did not identify additional novel pathogenic mutations. Our findings link a pathogenic PRKAR1B mutation to a novel hereditary neurodegenerative disorder and suggest an altered protein kinase A function through a reduced binding of the regulatory subunit to the A-kinase anchoring protein and the catalytic subunit of protein kinase A, which might result in subcellular dislocalization of the catalytic subunit and hyperphosphorylation of intermediate filaments.

Neuropsychiatric symptoms (NPSs) have a large impact on the quality of life of patients with dementia. A few studies have compared neuropsychiatric disturbances between dementia subtypes, but the results were conflicting. In the present study, we investigated whether the prevalence of NPSs differs between Alzheimer's disease (AD) and vascular dementia (VaD). The merit of our study is that we used clinical as well as histopathological information to differentiate between dementia subtypes. This retrospective descriptive study comprised 80 brains obtained from donors to the Netherlands Brain Bank between 1984 and 2010. These donors were diagnosed postmortem with AD (n = 40) or VaD (n = 40). We assessed the presence of NPSs by reviewing the information found in the patients' medical files. The most prevalent symptom in the sample as a whole was agitation (45 cases, 57.0%), followed by depression (33, 41.2%) and anxiety (28, 35.4%). Our study tried to contribute to the discussion by including, for the first time in the literature, a sample of AD and VaD patients with neuropathologically confirmed diagnoses. Since no significant differences were found between AD and VaD patients, we suggest that the prevalence of NPSs cannot be predicted from the diagnosis of AD or VaD.

A rare case of Gerstmann-Sträussler-Scheinker disease in a 36-year-old Dutch man is reported. The clinical phenotype was characterized by slowly progressive cognitive decline, later followed by ataxia and parkinsonism. Neuropathologic findings consisted of numerous amyloid plaques in the cerebellum, which showed positive staining for the abnormal prion protein (PrP(Sc)). In addition, there were tau accumulations around numerous amyloid deposits in the cerebral cortex, striatum, hippocampal formation, and midbrain. There was no spongiform degeneration. Western blot analysis showed the co-occurrence of 2 distinct abnormal prion protein species comprising an unglycosylated, protease-resistant fragment of approximately 8 kd, which was found to be truncated at both N- and C-terminal ends by epitope mapping, and a detergent-insoluble but protease-sensitive form of full-length PrP(Sc). Sequence analysis disclosed a mutation at codon 131 of the prion protein gene (PRNP), resulting in a valine-for-glycine substitution (G131V). The patient was heterozygous at the polymorphic codon 129 and carried the mutation on the methionine allele. To our knowledge, this is the second family worldwide in which this mutation has been identified. Gerstmann-Sträussler-Scheinker disease should be considered in patients with a clinical diagnosis of familial frontotemporal dementia.

Background and Purpose: Quantitative MR imaging techniques may improve the pathologic specificity of MR imaging regarding white matter abnormalities. Our purposes were to determine whether ADC, FA, MTR, and MRS metabolites correlate with the degree of white matter damage in patients with X-ALD; whether differences in ADC, FA, and MTR observed in vivo are retained in fresh and formalin-fixed postmortem brain tissue; and whether the differences predict histopathology., Materials and Methods: MRS metabolites, MTR, ADC, and FA, were determined in 7 patients with X-ALD in 3 white matter areas (NAWM, active demyelination, and complete demyelination) and were compared with values obtained in 14 controls. MTR, ADC, and FA were assessed in postmortem brains from 15 patients with X-ALD and 5 controls. Values were correlated with the degree of astrogliosis and density of myelin, axons, and cells. Equations to estimate histopathology from MR imaging parameters were calculated by linear regression analysis., Results: MRS showed increased mIns, Lac, and Cho and decreased tNAA in living patients with X-ALD; the values depended on the degree of demyelination. MTR, ADC, and FA values were different in postmortem than in vivo white matter, but differences related to degrees of white matter damage were retained. ADC was high and FA and MTR were low in abnormal white matter. Correlations between histopathologic findings and MR imaging parameters were strong. A combination of ADC and FA predicted pathologic parameters best., Conclusions: Changes in quantitative MR imaging parameters, present in living patients and related to the severity of white matter pathology, are retained in postmortem brain tissue. MR imaging parameters predict white matter histopathologic parameters.

Objective: To compare survival and to identify prognostic predictors for progressive supranuclear palsy and frontotemporal dementia., Background: Progressive supranuclear palsy (PSP) and frontotemporal dementia (FTD) are related disorders. Homozygosity for H1 haplotype is associated with PSP, whereas several MAPT mutations have been identified in FTLD-tau. Survival duration probably reflects underlying pathophysiology or disease., Methods: Patients with PSP and FTD were recruited by nationwide referral. Survival of 354 FTD patients was compared with that of 197 PSP patients. Cox regression analysis was performed to identify prognostic predictors. FTLD-tau was defined as Pick disease and FTDP-17 with MAPT mutations. Semiquantitative evaluation of tau-positive pathology was performed on all pathologically proven cases., Results: The median survival of PSP patients (8.0 years; 95% CI 7.3 to 8.7) was significantly shorter than that of FTD patients (9.9 years; 95% CI 9.2 to 10.6). Corrected for demographic differences, PSP patients were still significantly more at risk of dying than FTD patients. In PSP, male gender, older onset-age and higher PSP Rating Scale score were identified as independent predictors for shorter survival, whereas in FTD a positive family history and an older onset-age were associated with a poor prognosis. The difference in hazard rate was even more pronounced when comparing pathologically proven cases of PSP with FTLD-tau., Conclusion: Survival of PSP patients is shorter than that of FTD patients, and probably reflects a more aggressive disease process in PSP. Independent predictors of shorter survival in PSP were male gender, older onset-age and higher PSP rating scale score, whereas in FTD a positive family history and higher onset-age were predictors for worse prognosis.

Unlabelled: Meynen G, Van Stralen H, Smit JH, Kamphorst W, Swaab DF, Hoogendijk WJG. Relation between neuritic plaques and depressive state in Alzheimer's disease., Background: To investigate for the first time in a prospective study the relationship between depressive state and the neuropathological hallmarks of Alzheimer's disease, using a scale for depressive symptoms in dementia, while controlling for clinical severity of dementia., Method: Within the framework of a prospective longitudinal study of depression in Alzheimer's disease, patients with dementia underwent a clinical evaluation every six months during the last years of their lives, using the Cornell scale for depression in dementia to assess depressive symptoms and using the Functional Assessment Staging scale to control for clinical severity of dementia. The brains of 43 Alzheimer patients were obtained. The last clinical evaluations prior to death together with post-mortem neuropathology measures were analysed., Results: We found a correlation between the Cornell scores and the sum score for the density of neuritic plaques in the entire cortex (p = 0.027), and even stronger in the temporal cortex (p = 0.012). The observed correlations were independent of sex, age of death, clinical dementia severity and duration of Alzheimer's disease., Conclusions: This study shows a positive relationship between depressive state at time of death and the presence of neuritic plaques in Alzheimer's disease, which is independent of the clinical severity of dementia.

Background: Understanding the aetiologies of neurodegenerative diseases such as Alzheimer's disease (AD), Pick's disease (PiD), Progressive Supranuclear Palsy (PSP) and Frontotemporal dementia (FTD) is often hampered by the considerable clinical and molecular overlap between these diseases and normal ageing. The development of high throughput genomic technologies such as microarrays provide a new molecular tool to gain insight in the complexity and relationships between diseases, as they provide data on the simultaneous activity of multiple genes, gene networks and cellular pathways., Methodology/principal Findings: We have constructed genome wide expression profiles from snap frozen post-mortem tissue from the medial temporal lobe of patients with four neurodegenerative disorders (5 AD, 5 PSP, 5 PiD and 5 FTD patients) and 5 control subjects. All patients were matched for age, gender, ApoE-epsilon and MAPT (tau) haplotype. From all groups a total of 790 probes were shown to be differently expressed when compared to control individuals. The results from these experiments were then used to investigate the correlations between clinical, pathological and molecular findings. From the 790 identified probes we extracted a gene set of 166 probes whose expression could discriminate between these disorders and normal ageing., Conclusions/significance: From genome wide expression profiles we extracted a gene set of 166 probes whose expression could discriminate between neurological disorders and normal ageing. This gene set can be further developed into an accurate microarray-based classification test. Furthermore, from this dataset we extracted a disease specific set of genes and identified two aging related transcription factors (FOXO1A and FOXO3A) as possible drug targets related to neurodegenerative disease.

Background: Progressive supranuclear palsy (PSP) is a progressive neurodegenerative disorder characterized by aggregates of the microtubule-associated protein tau (MAPT). A nonsignificant trend for positive family history has been observed in two case-control studies and several pedigrees with familial clustering of parkinsonism have been described. Occasionally, mutations in MAPT are found in patients with a clinical phenotype similar to PSP. In this case-control study, we compared the occurrence of dementia and parkinsonism among first-degree relatives of patients with PSP with an age- and sex-matched control group., Methods: Family history of dementia and parkinsonism was collected from all first-degree relatives of patients with PSP who fulfilled the international National Institute of Neurological Disorders and Stroke criteria for PSP. Age- and sex-matched controls were selected from the Rotterdam Study. Genetic testing and pathologic examination was performed in a subset of familial PSP cases., Results: Fifty-seven (33%) of the 172 patients with PSP had at least one first-degree relative who had dementia or parkinsonism compared to 131 (25%) of the control subjects (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.01-2.13). In patients with PSP, more first-degree relatives with parkinsonism were observed compared to controls, with an OR 3.9 (95% CI 1.99-7.61). Twelve patients with PSP (7%) fulfilled the criteria for an autosomal dominant mode of transmission. The intrafamilial phenotype within these pedigrees varied among PSP, dementia, tremor, and parkinsonism. Genetic studies revealed one patient with a P301L mutation in MAPT. Pathologic examination of five familial cases confirmed the clinical diagnosis of PSP, with predominant four repeat tau pathology in affected brain areas., Conclusion: This study demonstrates familial aggregation of parkinsonism in progressive supranuclear palsy.

Background: Frontotemporal dementia (FTD) is the second most common type of presenile dementia and can be distinguished into various clinical variants. The identification of MAPT and GRN defects and the discovery of the TDP-43 protein in FTD have led to the classification of pathologic and genetic subtypes. In addition to these genetic subtypes, there exist familial forms of FTD with unknown genetic defects., Methods: We investigated the frequency, demographic, and clinical data of patients with FTD with a positive family history in our prospective cohort of 364 patients. Genetic analysis of genes associated with FTD was performed on all patients with a positive family history. Immunohistochemical studies were carried out with a panel of antibodies (tau, ubiquitin, TDP-43) in brains collected at autopsy., Results: In the total cohort of 364 patients, 27% had a positive family history suggestive for an autosomal mode of inheritance, including MAPT (11%) and GRN (6%) mutations. We identified a new Gln300X GRN mutation in a patient with a sporadic FTD. The mean age at onset in GRN patients (61.8 +/- 9.9 years) was higher than MAPT patients (52.4 +/- 5.9 years). In the remaining 10% of patients with suggestive autosomal dominant inheritance, the genetic defect has yet to be identified. Neuropathologically, this group can be distinguished into familial FTLD+MND and familial FTLD-U with hippocampal sclerosis., Conclusion: Future genetic studies need to identify genetic defects in at least two distinct familial forms of frontotemporal dementia (FTD) with unknown genetic defects: frontotemporal lobe degeneration with ubiquitin-positive inclusions with hippocampal sclerosis and frontotemporal lobe degeneration with motor neuron disease.

It has been recognized that molecular classifications will form the basis for neuropathological diagnostic work in the future. Consequently, in order to reach a diagnosis of Alzheimer's disease (AD), the presence of hyperphosphorylated tau (HP-tau) and beta-amyloid protein in brain tissue must be unequivocal. In addition, the stepwise progression of pathology needs to be assessed. This paper deals exclusively with the regional assessment of AD-related HP-tau pathology. The objective was to provide straightforward instructions to aid in the assessment of AD-related immunohistochemically (IHC) detected HP-tau pathology and to test the concordance of assessments made by 25 independent evaluators. The assessment of progression in 7-microm-thick sections was based on assessment of IHC labeled HP-tau immunoreactive neuropil threads (NTs). Our results indicate that good agreement can be reached when the lesions are substantial, i.e., the lesions have reached isocortical structures (stage V-VI absolute agreement 91%), whereas when only mild subtle lesions were present the agreement was poorer (I-II absolute agreement 50%). Thus, in a research setting when the extent of lesions is mild, it is strongly recommended that the assessment of lesions should be carried out by at least two independent observers.

To determine the reliability of assessment of alpha-synuclein-immunoreactive (alphaS-IR) structures by neuropathologists, 28 evaluators from 17 centers of BrainNet Europe examined current methods and reproducibility of alphaS-IR evaluation using a tissue microarray (TMA) technique. Tissue microarray blocks were constructed of samples from the participating centers that contained alphaS-IR structures. Slides from these blocks were stained in each center and assessed for neuronal perikaryal inclusions, neurites, and glial cytoplasmic inclusions. The study was performed in 2 phases. First, the TMA slides were stained with the antibody of the center's choice. In this phase, 59% of the sections were of good or acceptable quality, and 4 of 9 antibodies used performed consistently. Differences in interpretation and categorization of alphaS-IR structures, however, led to differing results between the laboratories. Prior to the second phase, the neuropathologists participated in a training session on the evaluation of alphaS-IR structures. Based on the results of the first phase, selected antibodies using designated antigen retrieval methods were then applied to TMA slides in the second phase. When the designated methods of both staining and evaluation were applied, all 26 subsequently stained TMA sections evaluated were of good/acceptable quality, and a high level of concordance in the assessment of the presence or absence of specific alphaS-IR structures was achieved. A semiquantitative assessment of alphaS-IR neuronal perikaryal inclusions yielded agreements ranging from 49% to 82%, with best concordance in cortical core samples. These results suggest that rigorous methodology and dichotomized assessment (i.e. determining the presence or absence of alphaS-IR) should be applied, and that semiquantitative assessment can be recommended only for the cortical samples. Moreover, the study demonstrates that there are limitations in the scoring of alphaS-IR structures.

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a progressive cerebral white matter disease with onset in childhood, caused by mutations in the MLC1 gene. MLC1 is a protein with unknown function that is mainly expressed in the brain in astrocytic endfeet at the blood-brain and cerebrospinal fluid-brain barriers. It shares its localization at astrocytic endfeet with the dystrophin-associated glycoprotein complex (DGC). The objective of the present study was to investigate the possible association of MLC1 with the DGC. To test this hypothesis, (co)-localization of DGC-proteins and MLC1 was analyzed by immunohistochemical stainings in gliotic brain tissue from a patient with multiple sclerosis, in glioblastoma tissue and in brain tissue from an MLC patient. In control tissue, a direct protein interaction was tested by immunoprecipitation. Results revealed that MLC1 is co-localized with DGC-proteins in gliotic brain tissue. We demonstrated that both MLC1 and aquaporin-4, a member of the DGC, were redistributed in glioblastoma cells. In MLC brain tissue, we showed absence of MLC1 and altered expression of several DGC-proteins. We demonstrated a direct protein interaction between MLC1 and Kir4.1. From these results we conclude that MLC1 is associated with the DGC at astrocytic endfeet.

Chemokines mediate selective recruitment of leukocyte subsets into the CNS during inflammatory episodes. We hypothesised that functional polymorphisms in CCR5 and CCL5 influence perivascular leukocyte infiltration, inflammation, axonal loss, and remyelination, and disease course. Therefore, we determined genotypes at four possibly functional polymorphisms in CCR5 and CCL5 for 637 patients and 92 brain donors with multiple sclerosis (MS). For a subset of 192 patients, MRI data were available. We found that low-producer allele CCL5-403*G was associated with reduced risk of severe axonal loss, whereas high-producer allele CCL5-403*A was associated with a worse clinical disease course measured by the MS Functional Composite Score and MS Severity Score. Low-producer allele CCR5+303*G was associated with reduced T2 hyperintense and T1 hypointense lesion volumes on MRI, and high-producer allele CCR5+303*A with early age at onset. Furthermore, low-producer allele CCR5Delta32 was associated with reduced T2 lesion volume, lower black hole ratio on MRI, and with a higher percentage of lesions with signs of remyelination, histopathologically. In summary, our multifaceted study supports the notion that polymorphisms in CCL5 and CCR5 modify the course of MS.

Background: Progressive supranuclear palsy (PSP) is a progressive hypokinetic rigid disorder with supranuclear gaze palsy and frequent falls. Although clinical consensus criteria are available, an atypical presentation may lead to clinical misdiagnosis in the initial phase. In the present study we investigated the clinical presentation of PSP and its relationship to initial clinical diagnosis and survival., Methods: We ascertained patients with PSP in a prospective cohort by nationwide referral from neurologists and nursing home physicians. All patients underwent a structural interview and clinical examination before entering the study. Medical records were reviewed for the presence of symptoms during the first 2 years., Results: A total of 152 patients ascertained between 2002 and 2005 fulfilled the international consensus criteria for PSP. Categorical principal component analysis of clinical symptoms within the first 2 years showed apart from a cluster of typical PSP symptoms, the clustering of cognitive dysfunction and behavioral changes. Further analysis showed that 20% of patients had a predominant frontal presentation with less than two other PSP symptoms. Survival analysis showed that this subgroup had a similar prognosis to that of the total group of patients with PSP., Conclusions: There exists a subgroup of patients with progressive supranuclear palsy (PSP) with a predominant frontal presentation, who progressed into typical PSP over the course of the disease.

Frontotemporal dementia is accompanied by motor neuron disease (FTD + MND) in approximately 10% of cases. There is accumulating evidence for a clinicopathological overlap between FTD and MND based on observations of familial aggregation and neuropathological findings of ubiquitin-positive neuronal cytoplasmatic inclusions (NCI) in lower motor neurons, hippocampus and neocortex in both conditions. Several familial forms exist with different genetic loci and defects. We investigated the familial aggregation and clinical presentation of FTD + MND cases in a large cohort of 368 FTD patients in The Netherlands. Immunohistochemistry of available brain tissue of deceased patients was investigated using a panel of antibodies including ubiquitin, p62 and TAR DNA-binding protein of 43 kDa antibodies. A total of eight patients coming from six families had a family history positive for FTD + MND (mean age at onset 53.2 +/- 8.4 years). Five patients presented with behavioural changes and cognitive changes followed by motor neuron disease, whereas symptoms of motor neuron disease were the presenting features in the remaining three patients. Other affected relatives in these families showed dementia/FTD, MND or FTD + MND reflecting the clinical interfamilial variation. No mutations were identified in any of the candidate genes, including Superoxide Dismutase 1, dynactin, angiogenin, Microtubule-Associated Protein Tau, valosin-containing protein and progranulin. Available brain tissue of five patients with familial FTD + MND showed NCI in hippocampus, neocortex and spinal cord in all, and neuronal intranuclear inclusions (NII) in two brains. TDP-43 antibody showed robust staining of neuronal inclusions similar in distribution and morphology to NCI and NII. Additionally, TDP-43 antibody also stained ubiquitin-negative glial inclusions in the basal striatum of one case. In conclusion, there exists considerable clinical variation within families with FTD + MND, which may be determined by other genetic or environmental factors. NII are also found in some cases of familial FTD + MND without Progranulin mutations. The observation of glial TDP-43 positive inclusions in one brain is very interesting, although their pathophysiological significance is yet unknown.

Amyloid beta (Abeta) immunoreactivity in neurons was examined in brains of 32 control subjects, 31 people with Down syndrome, and 36 patients with sporadic Alzheimer's disease to determine if intraneuronal Abeta immunoreactivity is an early manifestation of Alzheimer-type pathology leading to fibrillar plaque formation and/or neurofibrillary degeneration. The appearance of Abeta immunoreactivity in neurons in infants and stable neuron-type specific Abeta immunoreactivity in a majority of brain structures during late childhood, adulthood, and normal aging does not support this hypothesis. The absence or detection of only traces of reaction with antibodies against 4-13 aa and 8-17 aa of Abeta in neurons indicated that intraneuronal Abeta was mainly a product of alpha- and gamma-secretases (Abeta(17-40/42)). The presence of N-terminally truncated Abeta(17-40) and Abeta(17-42) in the control brains was confirmed by Western blotting and the identity of Abeta(17-40) was confirmed by mass spectrometry. The prevalence of products of alpha- and gamma -secretases in neurons and beta- and gamma-secretases in plaques argues against major contribution of Abeta-immunopositive material detected in neuronal soma to amyloid deposit in plaques. The strongest intraneuronal Abeta(17-42) immunoreactivity was observed in structures with low susceptibility to fibrillar Abeta deposition, neurofibrillary degeneration, and neuronal loss compared to areas more vulnerable to Alzheimer-type pathology. These observations indicate that the intraneuronal Abeta immunoreactivity detected in this study is not a predictor of brain amyloidosis or neurofibrillary degeneration. The constant level of Abeta immunoreactivity in structures free from neuronal pathology during essentially the entire life span suggests that intraneuronal amino-terminally truncated Abeta represents a product of normal neuronal metabolism.

Tau mutations in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) are associated with changes in alternative splicing of exon 10. The DeltaK280 mutation in exon 10 is exceptional because in vitro observations suggest a dramatic effect on microtubule binding, enhanced self-aggregation, as well as a decrease of the 4R/3R ratio by the ablation of an exon splicing enhancer element. Using immunohistochemistry, Western blotting, and electron microscopy on brain material with the DeltaK280 mutation, we investigated which of these effects is most dominant in vivo. The brain showed abundant Pick bodies in several brain regions, which stained positive with 3-repeat-specific but not with 4-repeat-specific tau antibodies. Western blots of sarkosyl-insoluble tau showed exclusively three repeat (3R0N and 3R1N) tau in most regions, although some 4R1N could be detected in the frontal cortex. In addition, the sarkosyl-soluble tau fraction showed a significantly higher amount of 3-repeat tau. Because quantitative analysis of 4R and 3R mRNA transcripts showed a 4R/3R ratio of only 0.3, association between increased transcription and protein expression was observed. These observations confirm the postulated hypothesis that the DeltaK280 mutation abolishes a splice enhancer element, which overrules the decreased microtubule binding and enhanced self-aggregation.

Neuronal homoeostasis requires a constant balance between biosynthetic and catabolic processes. Eukaryotic cells primarily use two distinct mechanisms for degradation: the proteasome and autophagy of aggregates by the lysosomes. We focused on the UPS (ubiquitin-proteasome system). As a result of molecular misreading, misframed UBB (ubiquitin B) (UBB+1) is generated. UBB+1 accumulates in the neuritic plaques and neurofibrillary tangles in all patients with AD (Alzheimer's disease) and in the neuronal and glial hallmarks of other tauopathies and in polyglutamine diseases such as Huntington's disease. UBB+1 is not present in synucleinopathies such as Parkinson's disease. We showed that UBB+1 causes UPS dysfunction, aggregation and apoptotic cell death. UBB+1 is also present in non-neurological cells, hepatocytes of the diseased liver and in muscles during inclusion body myositis. Other frequently occurring (age-related) diseases such as Type 2 (non-insulin-dependent) diabetes mellitus are currently under investigation. These findings point to the importance of the UPS in diseases and open new avenues for target identification of the main players of the UPS. Treatment of these diseases with tools (e.g. viral RNA interference constructs) to intervene with specific targets is the next step.

This interlaboratory study evaluated the reproducibility of the assessments of neuritic plaques and neurofibrillary tangles (NFTs)--the hallmark lesions of Alzheimer disease--and compared the staining between the BrainNet Europe centers. To reduce the topography-related inconsistencies in assessments, we used a 2-mm tissue microarray (TMA) technique. The TMA block included 42 core samples taken from 21 paraffin blocks. The assessments were done on Bielschowsky and Gallyas silver stains using an immunohistochemical (IHC) method with antibodies directed to beta-amyloid (IHC/Abeta) and hyperphosphorylated tau (IHC/HPtau). The staining quality and the assessments differed between the participants, being most diverse with Bielschowsky (good/acceptable stain in 53% of centers) followed by Gallyas (good/acceptable stain in 57%) and IHC/Abeta (good/acceptable stain in 71%). The most uniform staining quality and assessment was obtained with the IHC/HPtau method (good/acceptable stain in 94% of centers). The neuropathologic diagnostic protocol (Consortium to Establish a Registry for Alzheimer Disease, Braak and Braak, and the National Institute of Aging and Reagan [NIA-Reagan] Institute) that was used significantly influenced the agreement, being highest with NIA-Reagan (54%) recommendations. This agreement was improved by visualization of NFTs using the IHC/HPtau method. Therefore, the IHC/HPtau methodology to visualize NFTs and neuropil threads should be considered as a method of choice in a future diagnostic protocol for Alzheimer disease.

Frameshift (+1) proteins such as APP(+1) and UBB(+1) accumulate in sporadic cases of Alzheimer disease (AD) and in older subjects with Down syndrome (DS). We investigated whether these proteins also accumulate at an early stage of neuropathogenesis in young DS individuals without neuropathology and in early-onset familial forms of AD (FAD), as well as in other tauopathies, such as Pick disease (PiD) or progressive supranuclear palsy (PSP). APP(+1) is present in many neurons and beaded neurites in very young cases of DS, which suggests that it is axonally transported. In older DS patients (>37 years), a mixed pattern of APP(+1) immunoreactivity was observed in healthy looking neurons and neurites, dystrophic neurites, in association with neuritic plaques, as well as neurofibrillary tangles. UBB(+1) immunoreactivity was exclusively present in AD type of neuropathology. A similar pattern of APP(+1) and UBB(+1) immunoreactivity was also observed for FAD and much less explicit in nondemented controls after the age of 51 years. Furthermore, we observed accumulation of +1 proteins in other types of tauopathies, such as PiD, frontotemporal dementia, PSP and argyrophylic grain disease. These data suggest that accumulation of +1 proteins contributes to the early stages of dementia and plays a pathogenic role in a number of diseases that involve the accumulation of tau.