Apolipoprotein D: a potential biomarker for cerebral amyloid angiopathy.

AIMS: We investigated the potential of apolipoprotein D (apoD) as cerebrospinal fluid (CSF) biomarker for cerebral amyloid angiopathy (CAA) after confirmation of its association with CAA pathology in human brain tissue. METHODS: The association of apoD with CAA pathology was analysed in human occipital lobe tissue of CAA (n = 9), Alzheimer's disease (AD) (n = 11) and healthy control cases (n = 11). ApoD levels were quantified in an age- and sex-matched CSF cohort of CAA patients (n = 31), AD patients (n = 27) and non-neurological controls (n = 67). The effects of confounding factors (age, sex, serum levels) on apoD levels were studied using CSF of non-neurological controls (age range 16-85 years), and paired CSF and serum samples. RESULTS: ApoD was strongly associated with amyloid deposits in vessels, but not with parenchymal plaques in human brain tissue. CSF apoD levels correlated with age and were higher in men than women in subjects >50 years. The apoD CSF/serum ratio correlated with the albumin ratio. When controlling for confounding factors, CSF apoD levels were significantly lower in CAA patients compared with controls and compared with AD patients (P = 0.0008). CONCLUSIONS: Our data show that apoD is specifically associated with CAA pathology and may be a CSF biomarker for CAA, but clinical application is complicated due to dependency on age, sex and blood-CSF barrier integrity. Well-controlled follow-up studies are required to determine whether apoD can be used as reliable biomarker for CAA.

Von Economo neurons are part of a larger neuronal population that are selectively vulnerable in C9orf72 frontotemporal dementia.

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

Neuropathological and genetic characteristics of a post-mortem series of cases with dementia with Lewy bodies clinically suspected of Creutzfeldt-Jakob's disease.

INTRODUCTION: The disease course of dementia with Lewy bodies (DLB) can be rapidly progressive, clinically resembling Creutzfeldt-Jakob's disease (CJD). To better understand factors contributing to this rapidly progressive disease course, we describe load and distribution of neuropathology, and the presence of possible disease-associated genetic defects in a post-mortem series of DLB cases clinically suspected of CJD. METHODS: We included pathologically confirmed DLB cases with a disease duration of 3.5 years or less from the Dutch Surveillance Center for Prion Diseases, collected between 1998 and 2014. Lewy body disease (LBD) and Alzheimer's disease (AD)-related pathology were staged and semi-quantitatively scored in selected brain regions. Whole exome sequencing analysis of known disease-associated genes, copy number analysis, APOE ε genotyping and C9orf72 repeat expansion analysis were performed to identify defects in genes with a well-established involvement in Parkinson's disease or AD. RESULTS: Diffuse LBD was present in nine cases, transitional LBD in six cases and brainstem-predominant LBD in one case. Neocortical alpha-synuclein load was significantly higher in cases with intermediate-to-high than in cases with low-to-none AD-related pathology (p = 0.007). We found two GBA variants (p.D140H and p.E326K) in one patient and two heterozygous rare variants of unknown significance in SORL1 in two patients. CONCLUSION: A high load of neocortical alpha-synuclein pathology was present in most, but not all DLB cases. Additional burden from presence of concomitant pathologies, synergistic effects and specific genetic defects in the known disease-associated genes may have contributed to the rapid disease progression.

Differential insular cortex subregional vulnerability to α-synuclein pathology in Parkinson's disease and dementia with Lewy bodies.

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

Pedunculopontine cholinergic cell loss in hallucinating Parkinson disease patients but not in dementia with Lewy bodies patients.

There is a cholinergic deficit in Parkinson disease (PD) and in dementia with Lewy bodies (DLB) that plays a role in a variety of clinical symptoms, including visual hallucinations (VH). The aim of this study was to assess cholinergic neuronal loss and PD and Alzheimer disease pathology in the pedunculopontine nucleus pars compacta (PPNc) of PD and DLB patients with VH. Postmortem brainstem tissue samples of 9 clinically diagnosed and pathologically confirmed PD patients with VH, 9 DLB patients with VH, and 9 age- and sex-matched nondemented controls were obtained from the Netherlands Brain Bank. Using a morphometric approach, we estimated the density of cholinergic neurons in the PPNc and determined the local load of α-synuclein-immunoreactive Lewy pathology, neurofibrillary tangles, and ß-amyloid plaques. Cholinergic cell density in the PPNc was significantly lower in PD compared with DLB patients with VH (-39%, p < 0.001) and controls (-41%, p < 0.001). Alpha-synuclein load was higher in PD, whereas ß-amyloid plaque pathology was more pronounced in DLB patients. The mean cell density in DLB patients was not significantly reduced compared with that in controls. These results may indicate different patterns of degeneration of cholinergic output structures in PD and DLB.

Neuropathology of the hippocampus in FTLD-Tau with Pick bodies: a study of the BrainNet Europe Consortium.

AIMS: Frontotemporal lobar degeneration with Pick bodies (Pick's disease) is characterized by the presence of tau immunoreactive spherical structures in the cytoplasm of neurones. In view of confusion about the molecular pathology of Pick's disease, we aimed to evaluate the spectrum of tau pathology and concomitant neurodegeneration-associated protein depositions in the characteristically affected hippocampus. METHODS: We evaluated immunoreactivity (IR) for tau (AT8, 3R, 4R), α-synuclein, TDP43, p62, and ubiquitin in the hippocampus, entorhinal and temporal cortex in 66 archival cases diagnosed neuropathologically as Pick's disease. RESULTS: Mean age at death was 68.2 years (range 49-96). Fifty-two (79%) brains showed 3R immunoreactive spherical inclusions in the granule cells of the dentate gyrus. These typical cases presented mainly with the behavioural variant of frontotemporal dementia, followed by progressive aphasia, mixed syndromes or early memory disturbance. α-Synuclein IR was seen only in occasional spherical tau-positive inclusions, TDP-43 IR was absent, and 4R IR was present only as neurofibrillary tangles in pyramidal neurones. Aß IR was observed in 16 cases; however, the overall level of Alzheimer's disease-related alterations was mainly low or intermediate (n = 3). Furthermore, we identified six cases with unclassifiable tauopathy. CONCLUSIONS: (i) Pick's disease may occur also in elderly patients and is characterized by a relatively uniform pathology with 3R tau inclusions particularly in the granule cells of dentate gyrus; (ii) even minor deviation from these morphological criteria suggests a different disorder; and (iii) immunohistological revision of archival cases expands the spectrum of tauopathies that require further classification.

Brain perfusion patterns in familial frontotemporal lobar degeneration.

OBJECTIVE: Frontotemporal lobar degeneration (FTLD) is a clinically, genetically, and pathologically heterogeneous disorder. The aim of this study was to compare clinical features and perfusion patterns on SPECT of patients with familial FTLD-TAR DNA binding protein 43 kDa (TDP) and MAPT mutations. METHODS: Patients were included if they had MAPT or GRN mutations, positive family history with pathologically proven FTLD in the patient or first-degree relative, or were part of FTD-MND families. All patients and 10 age- and gender-matched controls underwent measurement of brain perfusion using (99m)Tc-HMPAO SPECT. We used SPM8 to perform image processing and voxel-based group analyses (p < 0.001). Gender and age were included as nuisance variables in the design matrices. RESULTS: Of the 29 patients with familial FTLD, 19 had familial FTLD-TDP (GRN mutations in 6), and 10 had MAPT mutations. At clinical presentation, familial FTLD-TDP patients were older at onset (p = 0.030) and had more memory deficits (p = 0.011), whereas patients with MAPT had more naming deficits (p < 0.001) and obsessive-compulsive behavior (p = 0.001). The between-groups SPECT analyses revealed significantly less perfusion in the right frontal lobe, precuneus, cuneus, and inferior parietal lobule in familial FTLD-TDP, whereas significantly less perfusion was found in the left temporal and inferior frontal gyri in MAPT. Post hoc analysis of familial FTLD-TDP with unknown genetic defect vs MAPT revealed less perfusion in the right frontal and parietal lobe. CONCLUSION: Familial FTLD-TDP shows relatively more posterior hypoperfusion, including the precuneus and inferior parietal lobule, possibly related to significant memory impairment. Patients with MAPT were characterized by impaired perfusion of the temporal regions and naming deficits.

The early involvement of the innate immunity in the pathogenesis of late-onset Alzheimer's disease: neuropathological, epidemiological and genetic evidence.

The idea that an inflammatory process is involved in Alzheimer's disease (AD) was proposed already hundred years ago but only the past twenty years inflammation-related proteins have been identified within plaques. A number of acute-phase proteins colocalize with the extracellular amyloid fibrils, the so called Aß-associated proteins. Activated microglia and astrocytes surrounding amyloid deposits express receptors of innate immunity and secrete pro-inflammatory cytokines. In this paper we review the evidence for involvement of innate immunity in the early stages of the pathological cascade of AD. Diffuse plaques, the initial neuropathological lesion in the cerebral neocortex, contain next to Aß also apolipoprotein E, clusterin, α1-antichymotrypsin and activated complement proteins. Interestingly, genetic studies have shown gene-loci to be associated with AD for all these proteins, except α1-antichymotrpsin. Fibrillar Aß can, through stimulation of toll-like receptors and CD-14 on glial cells, activate pathways for increased production of pro-inflammatory cytokines. This pathway, inducing production of proinflammatory cytokines, is under genetic control. The finding that the responsiveness of the innate immunity is higher in offspring with a parental history of late-onset AD indicates heritable traits for AD that are related to inflammatory processes. Prospective epidemiological studies which report that higher serum levels of certain acute-phase proteins are associated with cognitive decline or dementia provide additional evidence for the early involvement of inflammation in AD pathogenesis. The reviewed neuropathological, epidemiological and genetic findings show evidence for involvement of the innate-immunity in the early stages of pathological cascade as well as for the hypothesis that the innate immunity contributes to the etiology of late-onset AD.

Dyshoric capillary cerebral amyloid angiopathy mimicking Creutzfeldt-Jakob disease.

BACKGROUND: Subjects fulfilling the World Health Organisation clinical diagnostic criteria for Creutzfeldt-Jakob disease (CJD) often have a different diagnosis at autopsy, including Alzheimer's disease. Cerebral amyloid angiopathy (CAA) is a common finding in Alzheimer's disease, and in rare cases this is particularly capillary CAA with dyshoric changes. METHODS: Six subjects with extensive capillary CAA with dyshoric changes, in addition to neurofibrillary tangles and in the absence of CJD pathology were found in a consecutive series of 225 clinically suspected CJD cases fulfilling criteria for possible or probable CJD clinical data and results of neuroimaging, electroencephalography and cerebrospinal fluid analysis were collected to assess what has led to the erroneous clinical diagnosis of CJD. RESULTS: All six patients had rapidly progressive dementia (mean 8.2 months, range 3-24). Four fulfilled criteria for 'probable' and one for 'possible CJD'. 14-3-3 Protein in CSF and/or EEG-findings supported the suspicion of CJD in five patients. DISCUSSION: Patients with a clinical suspicion of CJD, supported by EEG and/or CSF abnormalities can have severe capillary CAA with dyshoric changes in addition to the presence of neurofibrillary tangles. Possibly dyshoric capillary CAA can contribute to rapid clinical progression in dementia.

The first case of protease-sensitive prionopathy (PSPr) in The Netherlands: a patient with an unusual GSS-like clinical phenotype.

An atypical case of prion disease is described in a 54-year-old Dutch man, homozygous for valine at codon 129 of the prion protein gene (PRNP). The clinical phenotype was characterised by progressive dementia, spastic paraplegia and sensorimotor polyneuropathy. The disease duration was 20 months. Genetic analysis of PRNP did not reveal any abnormalities. Neuropathologically, only mild spongiform change and a coarse granular immunohistochemical staining for the abnormal prion protein, PrP(Sc), was observed, with poorly formed plaques in the molecular layer of the cerebellar cortex. However, Western blotting showed low but detectable levels of proteinase K(PK)-resistant PrP(Sc) occurring in an unusual ladder-like profile. These features define a phenotype that corresponds to the recently described protease-sensitive prionopathy (PSPr). Our report on the first Dutch patient with PSPr further expands the spectrum of prionopathies and exemplifies the need to re-evaluate cases of atypical prion disease.

Inherited Creutzfeldt-Jakob disease in a Dutch patient with a novel five octapeptide repeat insertion and unusual cerebellar morphology.

An atypical case of inherited Creutzfeldt-Jakob disease (CJD) is described in a 35-year-old Dutch woman, homozygous for methionine at codon 129 of the prion protein gene (PRNP). The clinical phenotype was characterised by slowly progressive cognitive decline and parkinsonism. Neuropathological findings consisted of scanty spongiosis and only faint to absent immunohistochemical staining for the abnormal prion protein, PrP(Sc), with patchy deposits in the cerebellar cortex. Purkinje cells were abnormally located in the molecular layer of the cerebellum. Western blot analysis showed the co-occurrence of PrP(Sc) types 1 and 2 with an unusual distribution. Sequence analysis disclosed a novel 120 bp insertion in the octapeptide repeat region of the PRNP, encoding five additional R2 octapeptide repeats. These features define an unusual neuropathological phenotype and novel genotype, further expanding the spectrum of genotype-phenotype correlations in inherited prion diseases and emphasising the need to carry out pre-mortem PRNP sequencing in all young patients with atypical dementias.

Panencephalopathic Creutzfeldt-Jakob disease in the Netherlands and the UK: clinical and pathological characteristics of nine patients.

AIMS: The panencephalopathic type of Creutzfeldt-Jakob disease (PECJD) has extensive abnormalities in cerebral white matter as well as the cortex. PECJD has rarely been described in Caucasians and debate continues on its classification and pathogenesis. We describe our experience of PECJD over a 14-year period of surveillance for CJD in the Netherlands and the UK. METHODS: Between 1993 and 2006, nine cases of PECJD were identified. Clinical, histological and biochemical characteristics of all patients were analysed and compared; all cases were classified clinically as sporadic CJD. RESULTS: The median age at onset was 57.8 years and median disease duration was 22 months. The average brain weight was 887 g. Most patients showed a two-stage clinical course with initial rapid deterioration to a state of akinetic mutism, which then persisted over a longer time scale. Neuropathological findings were characterized by severe global atrophy with status spongiosus. Cerebral white matter involvement tended to be associated with either disease duration or severity of cerebral cortical lesions. Five patients could be classified into the MM1 subtype of sporadic CJD, one patient into the MM2 subgroup and another into the MV2 subgroup. Two patients were heterozygous at codon 129 in the prion protein gene and contained both type 1 and type 2 PrP(res) isoforms in the brain. CONCLUSIONS: We believe that white matter pathology in PECJD represents an end-stage pattern that reflects secondary degeneration due to widespread cortical neuronal loss that occurs in the early part of the disease, rather than representing a primary lesion.

Canine X-linked muscular dystrophy in a family of Grand Basset Griffon Vendéen dogs.

Three related Grand Basset Griffon Vendéen (GBGV) dogs, two male and one female, with poor locomotion and muscle pain on palpation, were humanely destroyed at approximately 2 months of age and submitted for necropsy. Histopathological examination of skeletal muscles showed hyaline hypereosinophilic myofibres, hypertrophy and atrophy, calcification, necrosis, and mild proliferation of endomyseal connective tissue, as well as small basophilic fibres with internalized nuclei in rows, indicating regeneration. Immunohistochemical labelling for the carboxy-terminal domain of dystrophin, performed on skeletal muscle from one of the male dogs, was negative, whereas it was positive in skeletal muscle from a normal control dog. Both parents were clinically unaffected. These findings confirmed the diagnosis of canine X-linked muscular dystrophy (CXMD). To the authors' knowledge, this is the first report of CXMD in the GBGV breed, and one of very few cases in a female dog.

Rab6 is increased in Alzheimer's disease brain and correlates with endoplasmic reticulum stress.

Alzheimer's disease (AD) is characterized by deposits of aggregated proteins. Accumulation of aggregation-prone proteins activates protein quality control mechanisms, such as the unfolded protein response (UPR) in the endoplasmic reticulum (ER). We previously reported upregulation of the UPR marker BiP in AD brain. In this study, we investigated the small GTPase Rab6, which is involved in retrograde Golgi-ER trafficking and may function as a post-ER quality control system. Using immunohistochemistry and semiquantitative Western blotting, the expression of Rab6 was analysed in hippocampus, entorhinal and temporal cortex of 10 AD patients and six nondemented control subjects. Rab6 is upregulated in AD temporal cortex from Braak stage 3/4, the same stage that UPR activation is found. We observe increased neuronal Rab6 immunoreactivity in all brain areas examined. Although some neurones show colocalization of immunoreactivity for Rab6 and hyperphosphorylated tau, strong Rab6 staining does not colocalize with tangles. We find a highly significant correlation between the Rab6 and BiP levels. In vitro data show that Rab6 is not upregulated as a result of UPR activation or proteasome inhibition indicating an independent regulatory mechanism. Our data suggest that ER and post-ER protein quality control mechanisms are activated early in the pathology of AD.

The significance of neuroinflammation in understanding Alzheimer's disease.

The interest of scientists in the involvement of inflammation-related mechanisms in the pathogenesis of Alzheimer's disease (AD) goes back to the work of one of the pioneers of the study of this disease. About hundred years ago Oskar Fischer stated that the crucial step in the plaque formation is the extracellular deposition of a foreign substance that provokes an inflammatory reaction followed by a regenerative response of the surrounding nerve fibers. Eighty years later immunohistochemical studies revealed that amyloid plaques are indeed co-localized with a broad variety of inflammation-related proteins (complement factors, acute-phase proteins, pro-inflammatory cytokines) and clusters of activated microglia. These findings have led to the view that the amyloid plaque is the nidus of a non-immune mediated chronic inflammatory response locally induced by fibrillar A beta deposits. Recent neuropathological studies show a close relationship between fibrillar A beta deposits, inflammation and neuroregeneration in relatively early stages of AD pathology preceding late AD stages characterized by extensive tau-related neurofibrillary changes. In the present work we will review the role of inflammation in the early stage of AD pathology and particularly the role of inflammation in A beta metabolism and deposition. We also discuss the possibilities of inflammation-based therapeutic strategies in AD.

[The first patient with the new variant of Creutzfeldt-Jakob's disease in The Netherlands]. / De eerste patiënt in Nederland met de nieuwe variant van de ziekte van Creutzfeldt-Jakob.

A Dutch woman died at the age of 26 years, after a disease duration of 18 months, due to the new variant of Creutzfeldt-Jakob's disease (vCJD). She had never travelled to the United Kingdom and there was no history of potential iatrogenic exposure. However, she had worked in the catering and food production industry for the previous 6 years and had frequently consumed raw meat. The disease course showed the classical clinical picture of vCJD, which was confirmed by post-mortem examination of the brain. Contrary to classical sporadic CJD, patients with the variant disease are usually younger and present predominantly with psychiatric symptoms. Sensory complaints like pain and dysaesthesiae usually follow soon. Only later are these symptoms followed by rapidly progressive neurological symptoms and signs. All patients genotyped so far are homozygous for methionine on codon 129 of the prion protein gene. Recognition of the disease is of particular importance because of possible transmission via blood and tissues. In patients with rapidly progressive psychiatric symptoms and unexplained neurological signs, particularly sensory complaints, one must consider the possibility of vCJD.