- Email: [email protected]
NEURON-TO-NEURON TRANSMISSION OF ALPHA-SYNUCLEIN
P306
Poster Presentations: P1
pathological tau can transfer between cells and seed the misfolding of cytosolic soluble tau into aggregates. We have developed cell-based models to dissect the mechanisms behind the propagation of tau pathology and assess potential therapeutic strategies. Methods: Filamentous tau preparations were added to neuronal and non-neuronal cells expressing soluble tau. Their uptake and the subsequent seeded aggregation of endogenous tau was studied using flow cytometry, immunofluorescence and SDS-PAGE-Western blot. Biochemical assays were used to determine structural properties of the filamentous tau preparations. A series of tau mutants was engineered to study the role of primary structure and phosphorylation state of tau in seeded aggregation and propagation in cells. Results: Hyperphosphorylated and non-phosphorylated, native and synthetic filamentous tau preparations efficiently entered cells and seeded the self-perpetuating formation of hyperphosphorylated filamentous tau composed of endogenous protein, in a process that was time- and concentration- dependent. Native filamentous tau seeded with a much higher potency than synthetic filamentous tau. Biochemical analyses revealed conformational differences between the filament preparations, which could account for the difference in seeding potency. The ability of tau to form filaments was necessary for seeded aggregation to occur; however, alteration of tau phosphorylation at pathologically associated sites did not affect this process. Conclusions: We developed a cell-based model of pathological tau propagation, whereby the addition of minute quantities of exogenous filamentous tau induced the formation of intracellular hyperphosphorylated filamentous tau by direct interaction with endogenous soluble tau. Using this model we have been able to identify structural requirements of seed-competent tau. We present evidence that filamentous tau can adopt multiple conformations, which determines its efficiency at seeding aggregation of soluble tau in cells. This is reminiscent of protein ’strains,’ such as have been identified for prion protein.
P1-005
SELECTIVELY ENHANCING PATHOLOGICAL FORMS OF TAU VIA THE AUTOPHAGY PATHWAY
Adrianne Chesser1, Zhinian Lei2, Gail V.W. Johnson2, 1University of Rochester School of Medicine, Rochester, New York, United States; 2 University of Rochester Medical Center, Rochester, New York, United States. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD) is the leading cause of neurodegeneration worldwide. Unfortunately, there are limited therapeutic options, due in part to an incomplete understanding of disease pathogenesis. One pathological hallmark of AD is the intracellular accumulation of hyperphosphorylated and truncated forms of the microtubule associated protein tau. These pathological forms of tau are unable to appropriately interact with microtubules, facilitatiing neuronal damage in AD. In addition, there are data to indicate that pathological tau, particularly in its oligomeric form, causes toxicity. Impairment of protein degradative systems is likely a contributing factor to the accumulation and aggregation of tau in AD. Therefore interventions that result in the selective upregulation of pathways that result in the clearance pathological tau without further diminishing the pool of available functional tau are of significant interest. Methods: Mouse cortical cells that inducibly express a single form of tau-unmodified, D421 truncation, phosphomimetic or phosphonull at T231 or S262-were established. Using these lines, degradation profiles for each form of tau were established both in the basal condition and in the presence of inhibitors or activators of the different protein degradation pathways. Primary neurons were used for complementary studies with phosphoepitope antibodies. Results: Particular pathological forms of tau are preferentially cleared via the autophagy pathway. Additionally, activating the autophagy pathway leads to enhanced clearance of these potentially disease-mediating forms. Importantly, this process is specific. Treatment with trehalose, an activator of non mTor-dependent autophagy, is effective, while rapamycin is not. This may relate to the involvement of adaptor proteins that help chaperone pathological tau to autophagy. In particular, the adaptor protein NDP52 appears to be important. Expression of NDP52 is signaled by Nrf2, a transcription factor that can be activated by phytochemicals found
in common foods. Treating primary neurons with a Nrf2 agonist enhances clearance of AD-specific phosphoforms of tau. Conclusions: The ability to specifically target pathological tau to degradation will facilitate removing toxic species from the cell while preserving the pool of normal tau that is critical for neuronal function. The use of Nrf2 agonists for this effect offers an exciting novel therapeutic target.
P1-006
INTRAVENOUSLY INJECTED HUMAN APOLIPOPROTEIN A-I RAPIDLY ENTERS THE CENTRAL NERVOUS SYSTEM VIA THE CHOROID PLEXUS IN MICE
Sophie Stukas1, Jerome Robert1, Mike Lee1, Iva Kulic1, Nicole DeValle2, Michael Carr3, Jianjia Fan3, Dhananjay Namjoshi3, Kalistyne Lemke2, Michael Oda2, Cheryl Wellington3, 1University of British Columbia, Vancouver, British Columbia, Canada; 2Children’s Hospital of Oakland Research Institute, Oakland, California, United States; 3The University of British Columbia, Vancouver, British Columbia, Canada. Contact e-mail: [email protected] Background: Cerebrovascular dysfunction contributes significantly to the pathoetiology of Alzheimer’s disease (AD). Midlife vascular risk factors, such as hypertension, cardiovascular disease, diabetes, and dyslipidemia, increase the relative risk for AD. These comorbidities are all characterized by low and/or dysfunctional high-density lipoproteins (HDL), which itself is a suggested risk factor for AD. In addition to lipid transport, HDL enhances vasorelaxation, reduces inflammation and oxidative stress, and promotes endothelial cell survival and integrity. In mouse models of AD, apolipoprotein (apo) A-I, the primary protein component of HDL, reduces neuroinflammation, suppresses cerebrovascular Ab deposition, and protects cognitive function, making it an intriguing therapeutic target. However, how apoA-I, which is made only in the liver and intestine yet is present in cerebrospinal fluid (CSF), enters the central nervous system (CNS) is unknown. Methods: Endogenous levels of apoA-I in brain, liver, CSF, and plasma were measured by immunoblotting. Recombinant, fluorescently tagged, lipid-free human (h) apoA-I was injected into the tail vein of wild-type mice at doses ranging from 7.5-120mg/kg and tissue was collected 0.5-24h post injection. hapoA-I levels were measured by ELISA. Results: Steady state levels of endogenous murine apoA-I in CSF and brain are approximately 0.01% and 10-15% of its levels in plasma and liver, respectively. hapoA-I delivered via intravenous injection localizes to the choroid plexus within 0.5h and accumulates in a saturable, dose-dependent manner in brain. hapoA-I accumulates in the brain for up to 2h, after which it is turned over with a half-life of w133 minutes, 3 times longer than its 40-45 half0-life in plasma, liver, and kidney. In vitro, hapoA-I is taken up, specifically binds to, and is actively transported across confluent monolayers of primary human choroid epithelial cells. Conclusions: As apoA-I mRNA is undetectable in murine brain, apoA-I in the CNS is derived from the circulation. Following intravenous injection, hapoA-I rapidly and strongly localizes to the choroid plexus and can be transported across choroidal epithelial cells in vitro. These results suggest that plasma apoA-I gains access to the CNS primarily via the blood-CSF barrier.
P1-007
NEURON-TO-NEURON TRANSMISSION OF ALPHA-SYNUCLEIN
Jakob Domert1, Emelie Severinsson1, Lotta Agholme1, Chris Sackmann1, Sangeeta Nath2, Jessica Sigvardsson3, Lars Lannfelt4, Joakim Bergstr€om4, Martin Ingelsson4, Martin Hallbeck5, 1Link€oping University, Linkoping, Sweden; 2Link€oping University, Linkoping, Sweden; 3Bioarctic, Stockholm, Sweden; 4Uppsala University, Uppsala, Sweden; 5Link€oping University, Linkoping, Sweden. Contact e-mail: [email protected] Background: The progression of Alzheimer’s disease and Parkinson’s disease follows a hierarchical anatomical pattern. Recent evidence indicates that this could be caused by a prion-like spread of the disease with aggregates of b-amyloid and a-synuclein respectively, propagating from
Poster Presentations: P1 neuron-to-neuron. It is known that a-synuclein oligomers can transfer between cells but not if this requires neurites and synapses. We have previously visualized neuritic neuron-to-neuron transfer of b-amyloid, in an 3D co-culture system with differentiated neuron-like human SH-SY5Y cells. In this study we investigated if a-synuclein is transferred in a similar manner as b-amyloid. We also investigated the intracellular localization and toxicity of the transferred a-synuclein. Methods: Monomeric, oligomeric and fibrillar forms of a -synuclein were labeled with Cy3. SH-SY5Y neuroblastoma cells were extensively differentiated in an ECM gel with the addition of a cocktail of growth-factors and transfected with CellLightÒ endosome-GFP (acceptor cells). Retinoic acid differentiated SH-SY5Y cells were incubated with 1-2 mM monomeric, oligomeric or fibrillary a-synuclein for 3 h (donor cells). Donor cells and acceptor cells were co-cultured for up to 7 days, fixed and analyzed using confocal microscopy. Results: Monomeric, oligomeric and fibrillar a-synuclein forms were taken up by donor cells within 3 hours and remained in the cells for at least 48 hours. After 24 h of co-culture, all tested forms of a-synuclein were transferred from donor cells to acceptor cells if neuritic connections were present. Oligomers were transferred more extensively than monomers. The a-synuclein co-localized with markers for multi vesicular bodies, endosoms and lysosomes. Conclusions: Monomeric, oligomeric and fibrillar forms of a-synuclein were transmitted through neuritic connections from donor to acceptor cells. The transfer of a-synuclein seem to involve multivesicular bodies as well as the endosomal and lysosomal compartments. The high level of differentiation of the acceptor cells, producing neuritic connections and synapses, seemed necessary for the transfer. Thus, we have found many similarities between a-synuclein and b-amyloid transfer. P1-008
BLOOD-BASED BIOMARKERS OF ALZHEIMER’S DISEASE PATHOLOGY AND COGNITIVE DECLINE IN NON-DEMENTED ELDERLY
Sarah Westwood1, Emanuela Leoni2, Steven Lynham3, Mizanur Khondoker2, Steven Kiddle2, Martina Sattlecker2, Nicholas James Ashton2, Ricardo Sainz Fuertes2, Abdul Hye2, Chantal Bazenet2, Malcolm Ward2, Madhav Thambisetty4, Simon Lovestone5, 1King’s College London, London, United Kingdom; 2 King’s College London, Institute of Psychiatry, London, United Kingdom; 3 Proteomics Facility, Institute of Psychiatry, London, United Kingdom; 4 National Institute on Aging, Baltimore, Maryland, United States; 5King’s College London, London, United Kingdom. Contact e-mail: sarah. [email protected] Background: There is an urgent need for Alzheimers disease (AD) biomarkers that can detect the disease at the early pre-symptomatic stages. Case versus control study designs often ignore clinical heterogeneity in patients and neuropathology in controls resulting in markers with doubtful clinical utility. U sing markers of in vivo b -amyloid deposition (e.g. 11 C-PiB) combined with positron emission tomography (PET) or MRI to derive biologically relevant biomarkers associated with established endophenotypes of disease pathology is a better approach. Neuropathological hallmarks of AD (b -amyloid plaques and neurofibrillary tangles) are commonly reported in post-mortem brains of non-demented elderly individuals, suggesting these cases might represent preclinical AD and may be a good population in which to detect early AD biomarkers. Here we aimed to identify plasma biomarkers associated with AD endophenotypes of brain amyloid burden or brain atrophy in non-demented older individuals using two complimentary longitudinal discovery-phase proteomic analyses. Methods: Two-dimensional gel electrophoresis coupled with mass spectrometry was performed on longitudinal plasma samples from non-demented older individuals exhibiting a range of 11 C-PiB PET measures of amyloid load (n¼68, Baltimore Longitudinal Study of Aging). The relationship between protein levels and measures of brain atrophy, cognitive decline, and amyloid load were examined. A label-free LC-MS/MS approach targeted at low molecular weight proteins (<30kDa) was also performed on a subset of these subjects (n¼25) to enhance coverage of the plasma proteome. Validation of
P307
candidate biomarkers was performed in an independent cohort (n¼160, AddNeuroMed) using quantitative immunoassays and aptamer-based arrays. Results: We have identified 15 plasma proteins associated with brain amyloid load, atrophy and cognitive scores. Our longitudinal study design allowed us to explore dynamic changes in concentrations of plasma protein profiles in relation to rates of change in both measures of AD pathology and cognition. Validation experiments determined whether these candidate biomarkers of pathology performed in an AD cohort. Conclusions: Using two complimentary discovery techniques this project identifies longitudinal biomarker signatures in plasma that differ between individuals with and without neuropathological hallmarks of AD. Our findings support previous reports that plasma biomarkers have the potential to be used as a screening tool for AD.
P1-009
GENDER DIFFERENCES IN MEMORY-RELATED FUNCTIONAL CONNECTIVITY IN AGING AND GENETIC RISK FOR AD
Theresa M. Harrison1, Alison Burggren1, Gary Small2, Susan Bookheimer1, 1UCLA, Los Angeles, California, United States; 2 David Geffen School of Medicine at UCLA, Los Angeles, California, United States. Contact e-mail: [email protected] Background: The APOE4 allele has been shown to confer unequal risk for AD to men and women. Specifically, women with a single APOE4 allele are at 4-fold higher risk of developing AD than men with a single APOE4 allele. However, it remains unclear if other AD-risk genes show gender effects. In this study we examined gender effects in a paired-associates memory task and tested for gender-mediated differences conferred by the CLU risk allele. Methods: 75 participants were divided into two groups: men (n¼32) and women (n¼43). There were no significant differences between groups in age, APOE carrier status, or mental status as measured by the MMSE. Each subject underwent MRI scanning on a Siemens Allegra 3T scanner: whole-brain T1 structural and functional scanning with a paired-associates task. Functional imaging data was processed using FSL. A psychophysiological interaction (PPI) analysis strategy was used to interrogate functional coupling of the hippocampus with the rest of the brain during the retrieval phase of the task. A GLM that included regressors for each active phase of the task, a regressor for the timeseries of left hippocampus and the PPI regressor was used to analyze activation in individual subjects. CLU genotyping was completed using a Taq-Man assay. Results: A group model comparing men to women was completed with cluster thresholding (z¼2.3) and was FWE corrected at p¼0.05. Group analyses revealed regions of the medial prefrontal cortex and parahippocampal gyrus that were significantly active in men over women. Effect sizes for each participant were calculated from percent signal change extracted from an ROI grown around a peak activation coordinate (10, 48, 38; Z¼3.52). While there was no effect of gender on the relationship between CLU and effect size, there was an overall trend suggesting effect size increases with decreased CLU risk load (average effect size: CC¼-0.04, CT¼0.11, TT¼0.41). Conclusions: These findings indicate that women are not recruiting frontal regions important for initiating search during retrieval tasks as well as men. In addition, these data suggest that CLU is important for normal memory function across both genders. P1-010
BINDING CHARACTERIZATION OF TAU PET TRACER 18F-THK5117 IN NON-ALZHEIMER’S NEURODEGENERATIVE DISEASES
Ryuichi Harada1, Nobuyuki Okamura1, Shozo Furumoto2, Tetsuro Tago3, Takeo Yoshikawa2, Hiroyasu Akatsu4, Ren Iwata5, Hiroyuki Arai2, Kazuhiko Yanai2, Yukitsuka Kudo6, 1Tohoku University School of Medicine, Sendai, Japan; 2Tohoku University School of Medicine, Sendai, Japan; 3 CYRIC, Tohoku Univesity, Sendai, Japan; 4Choju Medical Institute, Toyohashi, Japan; 5CYRIC, Tohoku University, Sendai, Japan; 6Tohoku University Hospital, Sendai, Japan. Contact e-mail: [email protected]. ac.jp
Poster Presentations: P1
pathological tau can transfer between cells and seed the misfolding of cytosolic soluble tau into aggregates. We have developed cell-based models to dissect the mechanisms behind the propagation of tau pathology and assess potential therapeutic strategies. Methods: Filamentous tau preparations were added to neuronal and non-neuronal cells expressing soluble tau. Their uptake and the subsequent seeded aggregation of endogenous tau was studied using flow cytometry, immunofluorescence and SDS-PAGE-Western blot. Biochemical assays were used to determine structural properties of the filamentous tau preparations. A series of tau mutants was engineered to study the role of primary structure and phosphorylation state of tau in seeded aggregation and propagation in cells. Results: Hyperphosphorylated and non-phosphorylated, native and synthetic filamentous tau preparations efficiently entered cells and seeded the self-perpetuating formation of hyperphosphorylated filamentous tau composed of endogenous protein, in a process that was time- and concentration- dependent. Native filamentous tau seeded with a much higher potency than synthetic filamentous tau. Biochemical analyses revealed conformational differences between the filament preparations, which could account for the difference in seeding potency. The ability of tau to form filaments was necessary for seeded aggregation to occur; however, alteration of tau phosphorylation at pathologically associated sites did not affect this process. Conclusions: We developed a cell-based model of pathological tau propagation, whereby the addition of minute quantities of exogenous filamentous tau induced the formation of intracellular hyperphosphorylated filamentous tau by direct interaction with endogenous soluble tau. Using this model we have been able to identify structural requirements of seed-competent tau. We present evidence that filamentous tau can adopt multiple conformations, which determines its efficiency at seeding aggregation of soluble tau in cells. This is reminiscent of protein ’strains,’ such as have been identified for prion protein.
P1-005
SELECTIVELY ENHANCING PATHOLOGICAL FORMS OF TAU VIA THE AUTOPHAGY PATHWAY
Adrianne Chesser1, Zhinian Lei2, Gail V.W. Johnson2, 1University of Rochester School of Medicine, Rochester, New York, United States; 2 University of Rochester Medical Center, Rochester, New York, United States. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD) is the leading cause of neurodegeneration worldwide. Unfortunately, there are limited therapeutic options, due in part to an incomplete understanding of disease pathogenesis. One pathological hallmark of AD is the intracellular accumulation of hyperphosphorylated and truncated forms of the microtubule associated protein tau. These pathological forms of tau are unable to appropriately interact with microtubules, facilitatiing neuronal damage in AD. In addition, there are data to indicate that pathological tau, particularly in its oligomeric form, causes toxicity. Impairment of protein degradative systems is likely a contributing factor to the accumulation and aggregation of tau in AD. Therefore interventions that result in the selective upregulation of pathways that result in the clearance pathological tau without further diminishing the pool of available functional tau are of significant interest. Methods: Mouse cortical cells that inducibly express a single form of tau-unmodified, D421 truncation, phosphomimetic or phosphonull at T231 or S262-were established. Using these lines, degradation profiles for each form of tau were established both in the basal condition and in the presence of inhibitors or activators of the different protein degradation pathways. Primary neurons were used for complementary studies with phosphoepitope antibodies. Results: Particular pathological forms of tau are preferentially cleared via the autophagy pathway. Additionally, activating the autophagy pathway leads to enhanced clearance of these potentially disease-mediating forms. Importantly, this process is specific. Treatment with trehalose, an activator of non mTor-dependent autophagy, is effective, while rapamycin is not. This may relate to the involvement of adaptor proteins that help chaperone pathological tau to autophagy. In particular, the adaptor protein NDP52 appears to be important. Expression of NDP52 is signaled by Nrf2, a transcription factor that can be activated by phytochemicals found
in common foods. Treating primary neurons with a Nrf2 agonist enhances clearance of AD-specific phosphoforms of tau. Conclusions: The ability to specifically target pathological tau to degradation will facilitate removing toxic species from the cell while preserving the pool of normal tau that is critical for neuronal function. The use of Nrf2 agonists for this effect offers an exciting novel therapeutic target.
P1-006
INTRAVENOUSLY INJECTED HUMAN APOLIPOPROTEIN A-I RAPIDLY ENTERS THE CENTRAL NERVOUS SYSTEM VIA THE CHOROID PLEXUS IN MICE
Sophie Stukas1, Jerome Robert1, Mike Lee1, Iva Kulic1, Nicole DeValle2, Michael Carr3, Jianjia Fan3, Dhananjay Namjoshi3, Kalistyne Lemke2, Michael Oda2, Cheryl Wellington3, 1University of British Columbia, Vancouver, British Columbia, Canada; 2Children’s Hospital of Oakland Research Institute, Oakland, California, United States; 3The University of British Columbia, Vancouver, British Columbia, Canada. Contact e-mail: [email protected] Background: Cerebrovascular dysfunction contributes significantly to the pathoetiology of Alzheimer’s disease (AD). Midlife vascular risk factors, such as hypertension, cardiovascular disease, diabetes, and dyslipidemia, increase the relative risk for AD. These comorbidities are all characterized by low and/or dysfunctional high-density lipoproteins (HDL), which itself is a suggested risk factor for AD. In addition to lipid transport, HDL enhances vasorelaxation, reduces inflammation and oxidative stress, and promotes endothelial cell survival and integrity. In mouse models of AD, apolipoprotein (apo) A-I, the primary protein component of HDL, reduces neuroinflammation, suppresses cerebrovascular Ab deposition, and protects cognitive function, making it an intriguing therapeutic target. However, how apoA-I, which is made only in the liver and intestine yet is present in cerebrospinal fluid (CSF), enters the central nervous system (CNS) is unknown. Methods: Endogenous levels of apoA-I in brain, liver, CSF, and plasma were measured by immunoblotting. Recombinant, fluorescently tagged, lipid-free human (h) apoA-I was injected into the tail vein of wild-type mice at doses ranging from 7.5-120mg/kg and tissue was collected 0.5-24h post injection. hapoA-I levels were measured by ELISA. Results: Steady state levels of endogenous murine apoA-I in CSF and brain are approximately 0.01% and 10-15% of its levels in plasma and liver, respectively. hapoA-I delivered via intravenous injection localizes to the choroid plexus within 0.5h and accumulates in a saturable, dose-dependent manner in brain. hapoA-I accumulates in the brain for up to 2h, after which it is turned over with a half-life of w133 minutes, 3 times longer than its 40-45 half0-life in plasma, liver, and kidney. In vitro, hapoA-I is taken up, specifically binds to, and is actively transported across confluent monolayers of primary human choroid epithelial cells. Conclusions: As apoA-I mRNA is undetectable in murine brain, apoA-I in the CNS is derived from the circulation. Following intravenous injection, hapoA-I rapidly and strongly localizes to the choroid plexus and can be transported across choroidal epithelial cells in vitro. These results suggest that plasma apoA-I gains access to the CNS primarily via the blood-CSF barrier.
P1-007
NEURON-TO-NEURON TRANSMISSION OF ALPHA-SYNUCLEIN
Jakob Domert1, Emelie Severinsson1, Lotta Agholme1, Chris Sackmann1, Sangeeta Nath2, Jessica Sigvardsson3, Lars Lannfelt4, Joakim Bergstr€om4, Martin Ingelsson4, Martin Hallbeck5, 1Link€oping University, Linkoping, Sweden; 2Link€oping University, Linkoping, Sweden; 3Bioarctic, Stockholm, Sweden; 4Uppsala University, Uppsala, Sweden; 5Link€oping University, Linkoping, Sweden. Contact e-mail: [email protected] Background: The progression of Alzheimer’s disease and Parkinson’s disease follows a hierarchical anatomical pattern. Recent evidence indicates that this could be caused by a prion-like spread of the disease with aggregates of b-amyloid and a-synuclein respectively, propagating from
Poster Presentations: P1 neuron-to-neuron. It is known that a-synuclein oligomers can transfer between cells but not if this requires neurites and synapses. We have previously visualized neuritic neuron-to-neuron transfer of b-amyloid, in an 3D co-culture system with differentiated neuron-like human SH-SY5Y cells. In this study we investigated if a-synuclein is transferred in a similar manner as b-amyloid. We also investigated the intracellular localization and toxicity of the transferred a-synuclein. Methods: Monomeric, oligomeric and fibrillar forms of a -synuclein were labeled with Cy3. SH-SY5Y neuroblastoma cells were extensively differentiated in an ECM gel with the addition of a cocktail of growth-factors and transfected with CellLightÒ endosome-GFP (acceptor cells). Retinoic acid differentiated SH-SY5Y cells were incubated with 1-2 mM monomeric, oligomeric or fibrillary a-synuclein for 3 h (donor cells). Donor cells and acceptor cells were co-cultured for up to 7 days, fixed and analyzed using confocal microscopy. Results: Monomeric, oligomeric and fibrillar a-synuclein forms were taken up by donor cells within 3 hours and remained in the cells for at least 48 hours. After 24 h of co-culture, all tested forms of a-synuclein were transferred from donor cells to acceptor cells if neuritic connections were present. Oligomers were transferred more extensively than monomers. The a-synuclein co-localized with markers for multi vesicular bodies, endosoms and lysosomes. Conclusions: Monomeric, oligomeric and fibrillar forms of a-synuclein were transmitted through neuritic connections from donor to acceptor cells. The transfer of a-synuclein seem to involve multivesicular bodies as well as the endosomal and lysosomal compartments. The high level of differentiation of the acceptor cells, producing neuritic connections and synapses, seemed necessary for the transfer. Thus, we have found many similarities between a-synuclein and b-amyloid transfer. P1-008
BLOOD-BASED BIOMARKERS OF ALZHEIMER’S DISEASE PATHOLOGY AND COGNITIVE DECLINE IN NON-DEMENTED ELDERLY
Sarah Westwood1, Emanuela Leoni2, Steven Lynham3, Mizanur Khondoker2, Steven Kiddle2, Martina Sattlecker2, Nicholas James Ashton2, Ricardo Sainz Fuertes2, Abdul Hye2, Chantal Bazenet2, Malcolm Ward2, Madhav Thambisetty4, Simon Lovestone5, 1King’s College London, London, United Kingdom; 2 King’s College London, Institute of Psychiatry, London, United Kingdom; 3 Proteomics Facility, Institute of Psychiatry, London, United Kingdom; 4 National Institute on Aging, Baltimore, Maryland, United States; 5King’s College London, London, United Kingdom. Contact e-mail: sarah. [email protected] Background: There is an urgent need for Alzheimers disease (AD) biomarkers that can detect the disease at the early pre-symptomatic stages. Case versus control study designs often ignore clinical heterogeneity in patients and neuropathology in controls resulting in markers with doubtful clinical utility. U sing markers of in vivo b -amyloid deposition (e.g. 11 C-PiB) combined with positron emission tomography (PET) or MRI to derive biologically relevant biomarkers associated with established endophenotypes of disease pathology is a better approach. Neuropathological hallmarks of AD (b -amyloid plaques and neurofibrillary tangles) are commonly reported in post-mortem brains of non-demented elderly individuals, suggesting these cases might represent preclinical AD and may be a good population in which to detect early AD biomarkers. Here we aimed to identify plasma biomarkers associated with AD endophenotypes of brain amyloid burden or brain atrophy in non-demented older individuals using two complimentary longitudinal discovery-phase proteomic analyses. Methods: Two-dimensional gel electrophoresis coupled with mass spectrometry was performed on longitudinal plasma samples from non-demented older individuals exhibiting a range of 11 C-PiB PET measures of amyloid load (n¼68, Baltimore Longitudinal Study of Aging). The relationship between protein levels and measures of brain atrophy, cognitive decline, and amyloid load were examined. A label-free LC-MS/MS approach targeted at low molecular weight proteins (<30kDa) was also performed on a subset of these subjects (n¼25) to enhance coverage of the plasma proteome. Validation of
P307
candidate biomarkers was performed in an independent cohort (n¼160, AddNeuroMed) using quantitative immunoassays and aptamer-based arrays. Results: We have identified 15 plasma proteins associated with brain amyloid load, atrophy and cognitive scores. Our longitudinal study design allowed us to explore dynamic changes in concentrations of plasma protein profiles in relation to rates of change in both measures of AD pathology and cognition. Validation experiments determined whether these candidate biomarkers of pathology performed in an AD cohort. Conclusions: Using two complimentary discovery techniques this project identifies longitudinal biomarker signatures in plasma that differ between individuals with and without neuropathological hallmarks of AD. Our findings support previous reports that plasma biomarkers have the potential to be used as a screening tool for AD.
P1-009
GENDER DIFFERENCES IN MEMORY-RELATED FUNCTIONAL CONNECTIVITY IN AGING AND GENETIC RISK FOR AD
Theresa M. Harrison1, Alison Burggren1, Gary Small2, Susan Bookheimer1, 1UCLA, Los Angeles, California, United States; 2 David Geffen School of Medicine at UCLA, Los Angeles, California, United States. Contact e-mail: [email protected] Background: The APOE4 allele has been shown to confer unequal risk for AD to men and women. Specifically, women with a single APOE4 allele are at 4-fold higher risk of developing AD than men with a single APOE4 allele. However, it remains unclear if other AD-risk genes show gender effects. In this study we examined gender effects in a paired-associates memory task and tested for gender-mediated differences conferred by the CLU risk allele. Methods: 75 participants were divided into two groups: men (n¼32) and women (n¼43). There were no significant differences between groups in age, APOE carrier status, or mental status as measured by the MMSE. Each subject underwent MRI scanning on a Siemens Allegra 3T scanner: whole-brain T1 structural and functional scanning with a paired-associates task. Functional imaging data was processed using FSL. A psychophysiological interaction (PPI) analysis strategy was used to interrogate functional coupling of the hippocampus with the rest of the brain during the retrieval phase of the task. A GLM that included regressors for each active phase of the task, a regressor for the timeseries of left hippocampus and the PPI regressor was used to analyze activation in individual subjects. CLU genotyping was completed using a Taq-Man assay. Results: A group model comparing men to women was completed with cluster thresholding (z¼2.3) and was FWE corrected at p¼0.05. Group analyses revealed regions of the medial prefrontal cortex and parahippocampal gyrus that were significantly active in men over women. Effect sizes for each participant were calculated from percent signal change extracted from an ROI grown around a peak activation coordinate (10, 48, 38; Z¼3.52). While there was no effect of gender on the relationship between CLU and effect size, there was an overall trend suggesting effect size increases with decreased CLU risk load (average effect size: CC¼-0.04, CT¼0.11, TT¼0.41). Conclusions: These findings indicate that women are not recruiting frontal regions important for initiating search during retrieval tasks as well as men. In addition, these data suggest that CLU is important for normal memory function across both genders. P1-010
BINDING CHARACTERIZATION OF TAU PET TRACER 18F-THK5117 IN NON-ALZHEIMER’S NEURODEGENERATIVE DISEASES
Ryuichi Harada1, Nobuyuki Okamura1, Shozo Furumoto2, Tetsuro Tago3, Takeo Yoshikawa2, Hiroyasu Akatsu4, Ren Iwata5, Hiroyuki Arai2, Kazuhiko Yanai2, Yukitsuka Kudo6, 1Tohoku University School of Medicine, Sendai, Japan; 2Tohoku University School of Medicine, Sendai, Japan; 3 CYRIC, Tohoku Univesity, Sendai, Japan; 4Choju Medical Institute, Toyohashi, Japan; 5CYRIC, Tohoku University, Sendai, Japan; 6Tohoku University Hospital, Sendai, Japan. Contact e-mail: [email protected]. ac.jp