QUANTIFICATION OF TAU OLIGOMERS FROM MOUSE BRAIN TISSUE

Poster Presentations: Wednesday, July 27, 2016

Figure 1. Cytoplasmic neuronal p-tau inclusions in the left LC.

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Mixed Models (LMM), that included terms for OSAS, diagnosis, and the interactions between OSAS and diagnosis. All models were adjusted for APOE E4 status. Results: In the total sample there was no association between OSAS and CSF biomarkers. The relationship between OSAS and tau tended to be different between diagnostic groups (p-value interaction .095). Post-hoc analysis showed that AD patients with a history of OSAS had higher tau levels than those without OSAS (estimated mean [95% CI]: 845 [715-976] vs. 647 [549-744] pg/ml, p-value ¼ .02). OSAS was not associated with tau in SCD and MCI patients. There was no interaction between OSAS and diagnosis for CSF AB42 and ptau. Conclusions: We found that a history of OSAS is associated with higher CSF tau levels in AD. These findings could fit with the idea that hypoxia might have an additive effect to neuronal injury in AD, or vice versa, that patients with high tau levels are at increased risk of OSAS. However, inferences on causal relationships cannot be made given the observational nature of the study. P4-225

ANALYSIS OF SPATIO-TEMPORAL FEATURES OF HISTOPATHOLOGY IN MURINE ALZHEIMER’S DISEASE MODELS AND HUMAN ALZHEIMER’S DISEASE SAMPLES

Vera Niederkofler1, Christina Hoeller1, Joerg Neddens1, Ewald Auer1, Heinrich Roemer2, Johannes Attems3, Birgit Hutter-Paier1, 1QPS Austria, Grambach, Austria; 2University of Graz, Graz, Austria; 3Newcastle University, Newcastle, United Kingdom. Contact e-mail: vera. [email protected] Background: Alzheimer’s disease (AD) is one of the most common

Figure 2. Percent of left LC population with cytoplasmic neuronal p-tau inclusions.

modulate norepinephrine and to protect LC neurons may benefit AD patients. P4-224

ALZHEIMER’S DISEASE PATIENTS WITH OSAS HISTORY HAVE HIGHER CSF TAU LEVELS

Astrid M. Hooghiemstra1, Pieter Jelle Visser1,2, Rosalinde E. R. Slot1, Charlotte E. Teunissen1, Philip Scheltens1, Wiesje M. van der Flier1, 1VU University Medical Center, Amsterdam, Netherlands; 2Alzheimer Center Limburg, School for Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands. Contact e-mail: a.hooghiemstra@ vumc.nl Background: Obstructive sleep apnea syndrome (OSAS) occurs more frequently in Alzheimers disease (AD) than in controls. OSAS is characterized by the obstruction of the upper airway resulting in nocturnal intermittent hypoxia. Hypoxia has been found to be related to the Alzheimer biomarkers amyloid-beta and tau in animal studies. The aim of the present study was to investigate whether a history of OSAS is associated with cerebrospinal fluid (CSF) levels of amyloid-beta 42 (AB42), total tau (tau) and phosphorylated tau (ptau) in patients with subjective cognitive decline (SCD), mild cognitive impairment (MCI), and AD. Methods: We included 59 patients who reported OSAS in their medical history (age 63 (8) years, 11 (19%) female; 14 AD, 15 MCI, 30 SCD) from the Amsterdam Dementia Cohort. We matched these patients for baseline diagnosis, gender, age, and year of evaluation, on a 1:2 basis to patients without an OSAS history (N¼118). CSF AB42, tau and ptau were assessed using ELISA (Innotest). We assessed the association between OSAS and the CSF biomarkers with Linear

neurodegenerative diseases of the world. One of its major hallmarks is the hyperphosphorylation of tau protein leading to intracellular neurofibrillary tangles (NFTs) in neurons. These tangles represent an end stage of paired helical filament (PHF) aggregation, which are found in neuropil threads in early stages of dementia. The hyperphosphorylation occurs at different tau protein residues like serine, threonine and tyrosine, including several phospho-sites especially related to AD. However, appearance, quantity and location of NFTs are still not fully understood. Methods: Using indirect immunofluorescence and quantitative image analysis, tau pathologies in diseased and healthy human brain, as well as transgenic and non-transgenic APPSL mice were investigated. We analyzed three different phospho-sites (pSer199, pSer396 and pSer422) in cortical regions and the hippocampus of both specimens. This study thus attempts -to test if the antibodies work equally well on mouse and human tissue, and to analyze if tau protein load increases with age and Braak staging, respectively. Further, immunofluorescent labelings using the murine tissue were performed to check if APPSL mice present at all with a quantifiable tau pathology and can therefore be used as a dual model of APP and Tau pathology. Results: Results show that the antibodies worked well on both tissues. The immunofluorescent labelings with pSer199, pSer396 and pSer422 show an increase of tau positive signal with age and Braak stage for murine and human samples, respectively. Conclusions: Except for pSer199 the quantification of tau shows the same trend in both types of tissue so that APPSL mice could potentially be established as a useful model for human Tau histopathology. P4-226

QUANTIFICATION OF TAU OLIGOMERS FROM MOUSE BRAIN TISSUE

Seung-Pil Yang1, Yanfei Wang1, Marcy Taylor1, Christopher Barden1, Anandi Bhattacharya1, Erhu Lu1, Mark Reed1, Braden Sweeting1, Donald F. Weaver2, Fan Wu1, Arun Yadav1, 1Treventis Corporation,

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Poster Presentations: Wednesday, July 27, 2016

Toronto, ON, Canada; 2Krembil Research Institute, Toronto, ON, Canada. Contact e-mail: [email protected] Background: Abnormal aggregation and deposition of tau protein is a key pathological feature in many neurodegenerative diseases such as Alzheimer’s disease (AD) and frontotemporal dementia. There is a compelling body of evidence implicating tau oligomers rather than mature aggregates as the underlying pathogenic species in numerous tauopathies, therefore preventing tau oligomer formation is an attractive target for disease modification. Developing robust in vivo screening models to demonstrate target engagement and attenuation of oligomeric tau is an essential tool for advancing small and large molecule therapeutics towards the clinic. Here we report a natural history study in the rTg4510 mouse model of AD, whereby we biochemically quantify tau oligomers in the various brain regions of this transgenic mouse. Methods: Oligomeric tau was quantified in 2, 3, 4 and 5 month old rTg4510 mice using three biochemical assay systems. Two types of tau biosensor systems developed by Prof M. I. Diamond were utilized. The first is a biosensor cell using a protein fragment complementation system in which tau RD(P301S) is fused with either N-terminal fragment of Click Beetle Luciferase (Nluc) or C-terminal fragment of Click Beetle Luciferase (Cluc). The second is a highly sensitive FRET assay in which tau RD(P301S) is fused with either CFP or YFP. When tau oligomers are added to the medium of biosensor cells, it is translocated into the cells and induces oligomerization of either RD(P301S)-Nluc/Cluc or RD(P301S)-CFP/YFP. This leads to the formation of an active luciferase or FRET, respectively. Then the amount of tau oligomers is determined by measuring either luminescence or FRET depending on biosensor cell type, with recombinant tau oligomers as standard. The final assay is an ELISA system using HT7 as both capture and detection anti bodies that selectively quantifies oligomeric tau over monomeric tau. Results: Tau biosensor cells detected tau oligomers from soluble fractions of rTg4510 mouse brain, with good correlation between tau biosensor cell assay results and the single-site ELISA for tau oligomer. Conclusions: Tau biosensor cells are sensitive and reliable cell-based detection system to detect tau oligomers in transgenic mouse models of AD. P4-227

HIGH DENSITIES OF ACTIVATED MICROGLIA ARE PRESENT IN CORTICAL WHITE MATTER AND CORRESPOND TO REGIONS OF GREATEST ATROPHY IN PRIMARY PROGRESSIVE APHASIA

Daniel T. Ohm, Garam Kim, Tamar Gefen, Zach Parton, Eileen H. Bigio, Emily J. Rogalski, M. Marsel Mesulam, Changiz Geula, Northwestern University, Chicago, IL, USA. Contact e-mail: danielohm2012@u. northwestern.edu Background: While deposition of abnormal proteins and other pa-

thology in cortical gray matter in neurodegenerative disorders has received extensive experimental attention, little is known about the extent and nature of white matter abnormalities. Primary progressive aphasia (PPA) is a clinical dementia syndrome characterized by dissolution of language function and is associated with Alzheimer disease (AD) or frontotemporal lobar degeneration pathology. We have shown extensive activation of microglia in gray matter in PPA brains regardless of the underlying molecular pathology. Here we investigated activation of microglia in cortical white matter in PPA brains with AD or TDP-43 pathology, and its relationship with cortical atrophy. Methods: Brains of PPA-AD (n¼2) and PPA-TDP (n¼2) participants were cut into whole hemisphere sections, and a 1/24 series of sections were processed with immu-

nohistochemical or histopathological procedures to visualize plaques, tangles, TDP-43 inclusions, and HLA-DR-positive activated microglia. Atrophy was quantified using FreeSurfer software in three participants with structural MRI scans collected close to death, and assessed in one participant using clinical MRI scans. Paraffin-embedded sections from additional PPA-TDP participants with GRN mutations were also examined (n¼4). Results: Four cases with available MRI displayed pronounced asymmetric atrophy restricted to the perisylvian language network. Whole hemispheric sections displayed substantial asymmetric densities of activated microglia throughout the white matter that surpassed the densities in adjacent gray matter, and allowed demarcation of the white/gray matter junction with the naked eye. Examination of paraffinembedded sections confirmed presence of high densities of activated microglia in cortical white matter. The highest densities of activated microglia in white matter occurred asymmetrically in cortical areas affiliated with language function, and closely matched patterns of gray matter atrophy detected by MRI scans in each case. Conclusions: Microglia display a pattern of activation in PPA characterized by substantial accumulation in cortical white matter with highest densities at sites of greatest atrophy. While the extent of activation of microglia in white matter in other neurodegenerative disorders is incompletely understood, our findings point to the possibility that activated microglia play an active role in neurodegenerative mechanisms in the white matter, and correspond to in vivo cortical gray matter atrophy. P4-228

NEURONAL INTRACYTOPLASMIC PRP DEPOSITS IN DOMINANTLY INHERITED CREUTZFELDT-JAKOB DISEASE ASSOCIATED WITH THE PRNP E200K-129V HAPLOTYPE

Bernardino Ghetti1, Jill R. Murrell1, Rose M. Richardson1, Francine Epperson1, Pierluigi Gambetti2, Adrian L. Oblak1, 1Indiana University School of Medicine, Indianapolis, IN, USA; 2Case Western Reserve University, Cleveland, OH, USA. Contact e-mail: [email protected] Background: Familial prionopathies are neurodegenerative diseases

caused by mutations of the Prion Protein (PRNP) gene. They include familial Creutzfeldt-Jakob disease (fCJD), Fatal Familial Insomnia, Gerstmann-Str€ aussler-Scheinker disease, and PrP amyloid angiopathy. Approximately 20 mutations have been reported to be associated with fCJD and are transmitted in an autosomal dominant pattern. Clinical and neuropathologic features of fCJD are comparable to those of sporadic CJD. Methods: DNA was isolated from frozen brain tissue and the PRNPgene was sequenced. For histology, the following methods were used: Luxol fast blue/hematoxylin & eosin, Thioflavin S, and Woelcke-Heidenhain. For immunohistochemistry, antibodies against GAFP, tau (AT8), Ab (21F12, 10D5), PrP (3F4, 12F10), ubiquitin and a-synuclein were used. Results: In a family, 12 individuals died of a dementing illness. The brain of four members of this pedigree have been studied neuropathologically and by molecular genetics. The patients were four females, a mother and her three daughters, who died at the ages of 85, 56, 55 and 51, respectively. Neuropathologic examination revealed mild to moderate cerebral atrophy with preferential involvement of the frontal and temporal cortices and the hippocampus. There was extensive prion protein (PrP) immunopositivity with a synaptic pattern in the cerebral cortex, basal ganglia, amygdala, hippocampus and parahippocampal gyrus, cerebellum and midbrain. A significant finding was the presence of numerous neuronal intracytoplasmic PrP immunopositive inclusions in the cerebral cortex, basal ganglia, entorhinal cortex and dentate