Dataset Information

Tau Oligomer Pathology in Nucleus Basalis Neurons During the Progression of Alzheimer Disease.

ABSTRACT: Although tau is the primary constituent of neurofibrillary tangles (NFTs), evidence suggests that its toxic moiety is oligomeric in Alzheimer disease (AD). In this regard, tau oligomers correlate more strongly with neuronal loss than NFTs and exhibit neurotoxicity in preclinical AD models. Here, we investigated the spatiotemporal progression of oligomeric tau accumulation within the highly vulnerable cholinergic neurons of the nucleus basalis of Meynert (nbM) in AD. Tissue from subjects who died with a clinical diagnosis of no cognitive impairment, mild cognitive impairment, or AD was immunostained with the tau oligomeric complex 1 (TOC1) antibody, a marker of tau oligomers, and p75NTR, a cholinergic cell marker. Stereological estimates revealed a significant increase in the number of TOC1 nbM immunopositive (+) neurons with a concomitant decrease in p75NTR+?nbM neurons during the transition from mild cognitive impairment to AD. Immunofluorescence identified TOC1+?neurons that colocalized with the pretangle tau marker phospho-Ser422, which persisted into late stage NFTs immunoreactive for MN423. Analysis of the nbM subfields revealed a topographical caudal to rostral gradient of TOC1+?neurons during disease progression. Taken together, these data suggest that toxic tau oligomers accumulate caudorostrally in selectively vulnerable nbM neurons during the onset of AD.

SUBMITTER: Tiernan CT

PROVIDER: S-EPMC6251641 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature

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Tau Oligomer Pathology in Nucleus Basalis Neurons During the Progression of Alzheimer Disease.

Tiernan Chelsea T CT Mufson Elliott J EJ Kanaan Nicholas M NM Counts Scott E SE

Journal of neuropathology and experimental neurology 20180301 3

Although tau is the primary constituent of neurofibrillary tangles (NFTs), evidence suggests that its toxic moiety is oligomeric in Alzheimer disease (AD). In this regard, tau oligomers correlate more strongly with neuronal loss than NFTs and exhibit neurotoxicity in preclinical AD models. Here, we investigated the spatiotemporal progression of oligomeric tau accumulation within the highly vulnerable cholinergic neurons of the nucleus basalis of Meynert (nbM) in AD. Tissue from subjects who died ...[more]

PMID: 29378005

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Project description:ImportanceCorticolimbic patterns of neurofibrillary tangle (NFT) accumulation define neuropathologic subtypes of Alzheimer disease (AD), which underlie the clinical heterogeneity observed antemortem. The cholinergic system, which is the target of acetylcholinesterase inhibitor therapy, is selectively vulnerable in AD.ObjectiveTo investigate the major source of cholinergic innervation, the nucleus basalis of Meynert (nbM), in order to determine whether there is differential involvement of NFT accumulation or neuronal loss among AD subtypes.Design, setting, and participantsIn this cross-sectional study, retrospective abstraction of clinical records and quantitative assessment of NFTs and neuron counts in the nbM was completed in January 2019 at the Mayo Clinic using the Florida Autopsied Multi-Ethnic (FLAME) cohort, which had been accessioned from 1991 until 2015. The FLAME cohort is derived from the deeded autopsy program funded throughout the State of Florida's memory disorder clinic referral services. Of the 2809 consecutively accessioned FLAME cohort, 1464 were identified as neuropathologically diagnosed AD cases and nondemented normal controls available for clinicopathologic assessment. Quantification of NFTs and neuronal density in the anterior nbM was performed blinded to neuropathologic groupings.Main outcomes and measuresDemographic and clinical characteristics, including cognitive decline measured using the Mini-Mental State Examination score (range, 0-30), were evaluated. The anterior nbM was investigated quantitatively for neuronal loss and NFT accumulation.ResultsIn total, 1361 AD subtypes and 103 nondemented controls were assessed. The median (interquartile range) age at death was 72 (66-80) years in hippocampal sparing (HpSp) AD, 81 (76-86) years in typical AD, and 86 (82-90) years in limbic predominant AD. The median (interquartile range) count per 0.125 mm2 of thioflavin S-positive NFTs was highest in the nbM of HpSp AD (14 [9-20]; n?=?163), lower in typical AD (10 [5-16]; n?=?937), and lowest in limbic predominant AD (8 [5-11], n?=?163) (P?<?.001). The median (interquartile range) neuronal density per millimeters squared was lowest in HpSp AD cases (22 [17-28]; n?=?148), higher in typical AD (25 [19-30]; n?=?727), and highest in limbic predominant AD (26 [19-32]; n?=?127) (P?=?.002). Multivariable regression modeling of clinical and demographic variables was performed to assess overlap in NFT accumulation and neuronal density differences among AD subtypes. Higher NFT accumulation in the nbM was associated with younger age at onset for HpSp AD (?, -1.5; 95% CI, -2.9 to -0.15; P?=?.03) and typical AD (?, -3.2; 95% CI, -3.9 to -2.4; P?<?.001). In addition, higher NFT accumulation in the nbM of typical AD cases was associated with female sex (?, 2.5; 95% CI, 1.4-3.5; P?<?.001), apolipoprotein E ?4 allele (?, 1.3; 95% CI, 0.15-2.5; P?=?.03), and lower Mini-Mental State Examination scores (?, -1.8; 95% CI, -3.2 to -0.31; P?=?.02). Demographic and clinical progression variables were not associated with NFT accumulation in the nbM of limbic predominant AD cases.Conclusions and relevanceThese data provide supportive evidence that NFT accumulation in the nbM may underlie more widespread and severe cholinergic deficits in young-onset AD, in particular in patients with HpSp AD. Moreover, these findings underscore the importance of considering age at onset, sex, and apolipoprotein E genotype when assessing outcomes in AD.

Project description:ImportanceIn Alzheimer disease (AD), tau filaments form neuronal inclusions in neurites (neuropil threads) and in somata (neurofibrillary tangles), and neurite tau pathology constitutes the most common pathology. Positron emission tomography (PET) ligands have been developed to detect in vivo tau pathology in AD. However, the association of AD tau pathology post mortem with in vivo tau PET retention has not been established. Therefore, there is a need to investigate the associations of tau PET with postmortem tau pathology in AD.ObjectiveTo study the association of regional in vivo retention of the tau PET ligand [18F]flortaucipir (previously known as AV1451) with the density of tau neuropathology in the corresponding brain regions in a patient with AD.Design, setting, and participantsThe patient was a man in his 40s with AD caused by a PSEN1 mutation. Between May 2015 and December 2016, he underwent 2 [18F]flortaucipir PET scans at Lund University Hospital, Lund, Sweden. Postmortem analysis was performed 12 months after the last PET scan. Tau pathology was assessed using phosphorylated tau (AT8) immunohistochemistry and Gallyas silver staining. In addition to the regional total tau pathology burden, the density of tau-positive neurites and intrasomal tau tangles were quantified using a stereology-based method. Further, β-amyloid-containing plaques were detected using 4G8 immunohistochemistry. Data were analyzed between January 2018 and August 2018.Main outcomes and measuresRegional standardized uptake value ratios of [18F]flortaucipir were compared with the amount of tau pathology in the corresponding brain areas.ResultsIn this patient, the clinical disease symptoms progressed rapidly in life, paralleled with an annual increase of tau PET retention of 20% to 40% in many cortical regions. Compared with postmortem immunohistochemistry, regional in vivo uptake of [18F]flortaucipir was correlated with the density of tau-positive neurites (AT8: rs = 0.87; P < .001; Gallyas: rs = 0.92; P < .001), intrasomal tau tangles (AT8: rs = 0.65; P = .01; Gallyas: rs = 0.84; P < .001), and total tau burden (AT8: rs = 0.84; P < .001; Gallyas: rs = 0.82; P < .001). No correlations between [18F]flortaucipir and β-amyloid pathology were found.Conclusions and relevanceThese results indicate that [18F]flortaucipir PET retention is a robust in vivo measure of the total AD tau burden.

Dataset Information

Tau Oligomer Pathology in Nucleus Basalis Neurons During the Progression of Alzheimer Disease.

Publications

Tau Oligomer Pathology in Nucleus Basalis Neurons During the Progression of Alzheimer Disease.

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