P1116
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
Poster Presentations: Wednesday, July 27, 2016
nucleus of the cerebellum. Neuronal loss, gliosis and spongiform changes were observed in the same regions. Alzheimer disease pathology was also present in two members of the family. Conclusions: The E200K-129M haplotype is the most common form of fCJD while there are only five reported cases of E200K-129V haplotype in the literature. The presence of intraneuronal PrP immunopositive inclusions appears to be a consistent finding in subjects with the E200K mutation; however, their morphology needs to be further investigated with high resolution microscopy. Acknowledgements: P30AG010133; NIH P01 AG-14359, Charles S. Britton Fund and CDC UR8/CCU515004. P4-229
HOW ARE COGNITIVE IMPAIRMENT PATIENTS BEING DIAGNOSED?
Xiaohan Hu1,2, Eddie Jones3, Robert Wood3, Christopher M. Black1, Baishali M. Ambegaonkar1, Rezaul Karim Khandker1, 1Merck & Co., Inc., Kenilworth, NJ, USA; 2Temple University, Philadelphia, PA, USA; 3Adelphi Real World, Macclesfield, United Kingdom. Contact e-mail: xiaohan.hu@ merck.com Background: Patients with cognitive impairment (CI) may have different diagnostic experiences before being diagnosed; however it is not well understood whether experiencing different processes would affect patient outcomes. This analysis aimed to study the diagnostic pattern that CI patients have experienced. Methods: Data were taken from 2013 Adelphi Real World Dementia Disease Specific Programme, a cross-sectional survey of physicians, and patients over 50 years old with CI in France, Germany, Italy, Spain, the UK and the US. Physicians completed patient record forms containing patient demographics and patients’ diagnosis experience. Patients were classified into four CI subgroups based on their current mini–mental state examination (MMSE) score; prodromal (2430), mild (18-23), moderate (10-17) and severe (
