Diagnosing Alzheimers beforethe Alzheimers; Novel tools for early detection Nellie Byun, PhD Romina Gentier, MSc Rylan Allemang-Grand, BSc Elizabeth Steuer, BSc Jennifer Goldman, BA
Background Oligomer HypothesisSynapse loss does not require the presence of amyloid deposition (Mucke et al., 2000).Aβ oligomers are central nervous system neurotoxins which lead to disruptions insynaptic plasticity (Lambert et al., 1998).Aβ oligomers leads to synapse loss and disrupt glutamate receptor trafficking (Lacor etal., 2007).
Problem: Current diagnosis of AD relies on the denouement of cognitive function and atrophy of cortical tissue, symptoms predicting poor prognosis. Experimental AD therapies have likely been unsuccessful due to late diagnosis.
• Addressing a Critical Unmet Need:We need a Biomarker for early prediction of AD, prior to the aggregation of Amyloid plaques, tau pathology, synapse degeneration, neuron loss, and deterioration of cognitive function.• Significance:Early AD detection can facilitate drug discovery andtherapeutic efforts and potentially lead to successfuldiagnosis and prevention of AD
HypothesisAccumulation of low molecular weight amyloidfragments are an early predictor of AD and can bedetected by PET imaging.
AIMS:1. Development and characterization of a novel PET radioligand for detection of Ab oligomers1. Determining the relationship of Ab oligomers in brain with other AD pathology1. Algorithm for identifying at-risk individuals, human toxicity screen and PET trials
AIM 1:Development and characterization of a novel PETradioligand for detection of ADDLs in MgGill-TG thy1-APPrats Strategy: Multiple antibodies (Abs) have already been developed against Ab oligomers. In the cancer field, antibodies have been successfully (i.e., FDA approved) utilized as imaging agents, so the technology and expertise should be used in neuroscience. Methods: Screening and validation - Purchase Abs against oligomers (Nu-1, Nu-2, Nu-3, Nu-4) [See Alzforum antibody list] - Radiochemistry to label Abs with 18F and purify. - Perform microPET scans in anesthetized MgGill-TG thy1-APP and control rats; tail vein injection of 18F-Ab (0.75 and 1.5 mCi); n= 10/group - Perform Nanotech Assay (Mirkin) following PET scan to quantify Ab and determine sensitivity of PET ligands
AIM 2:Determining the spatial and temporal relationship of Aboligomer binding in brain with AD pathology• MgGill-TG thy1-APP rats housed in non-stressful environments• Behavior- Object Recognition, Morris Water Maze• Immunochemistry and quantification of Abeta aggregates, Tau pathology, synapse density, activated microglia, cell density, neurite morphology, number of neurons• Electrophysiology: miniEPSCs, LTP/LTD measurements (synapse density and plasticity measurements)
AIM 3:Algorithm to identify at-risk individuals, humantoxicity screen and PET trials • Family history of AD • APOE4 • Functional Test of olfactory dysfunction (U-Penn Smell Identification Test) • Body mass index • Type II Diabetes • History of Infection • Oral Hygiene • Exercise patterns • Diet Toxicity screen in humans Early trials in familial AD before plaque pathology
Cost and Resource UseFunding request: $500,000/year for 3 yearsY1: Radiotracer developmentCore costs-Animals and housing: $30,000 [$2/day/Cage]-PET Radiochemistry: $16,000 [$100/animal ($600/synthesis for n=6 animals)]-microPET scanning: $40,000 [$240/animal ($120/hour, 2 hours)]Supplies/Equipment-UPSIT (Sold by Sensonics, Inc): $26.95/test
Translational Potential and Future Directions• Algorithm for determination of risk Questionnaire • Family History of AD • Type-2 Diabetes • Lifestyle (diet, stress, exercise) • Decline in Olfactory function• PET Scans
References Mucke, L., Masliah, E., Yu, G.Q., Mallory, M., Rockenstein, E.M., Tatsuno, G., et al.(2000). High-level neuronal expression of A-beta (1-42) in wild-type humanamyloid protein precursor transgenic mice: synaptotoxicity without plaqueformation. Journal of Neuroscience, 1;20(11), 4050-4058. Lambert, M. P., Barlow, A. K., Chromy, B. A., Edwards, C., Freed, R., Liosatos, M.,et al. (1998). Diffusible, nonfibrillar ligands derived from Abeta1-42 are potentcentral nervous system neurotoxins. Proceedings of the National Academy ofSciences of the United States of America, 95, 6448–6453. Lacor, P. N., Buniel, M. C., Furlow, P. W., Clemente, A. S., Velasco, P. T., Wood,M., et al. (2007). Abeta oligomer-induced aberrations in synapse composition,shape, and density provide a molecular basis for loss of connectivity inAlzheimer’s disease. Journal of Neuroscience, 27, 796–807.
Thank You!• EURON, AHAF, ISAO• Drs. Harry Steinbusch, Claudio Cuello, Mark Mattson, William Klein, Bart Rutten, Paul Coleman, Cindy Lemere, Frank LaFerla, Jochen Walter, Jorg Bernard Schultz, Ilse Dewachter, Carol Colton, Michael Sofroniew, Jin-Moo Lee, Joana Palha,