HALLMARKS OF LATE-ONSET ALZHEIMER’S DISEASE IN A …
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HALLMARKS OF LATE-ONSET ALZHEIMER’S DISEASE IN A HUMANIZED MOUSE MODEL
For further information, please see:• MODEL-AD: www.modelad.org• AMP-AD knowledge portal: www.ampadportal.org• JAX AD models: https://www.jax.org/alzheimers• AlzForum research models: http://www.alzforum.org/research-models
Kevin P. Kotredes,1 Christoph Preuss,1 Ravi Pandey,1 Paul Territo,2 Adrian Oblak,2 Rima Kaddurah-Daouk,6 Matthias Arnold,7 Nicholas Seyfried,8 Duc Duong,8 Harriet Williams,1 Bruce Lamb,2 Stacey Rizzo,3 Gregory Carter,1 Mike Sasner,1 and Gareth Howell1 of the MODEL-AD Center1,2,3,4,5
ABSTRACTAlzheimer’s disease (AD) is a debilitating neurodegenerative disorderaffecting nearly 50 million patients worldwide, with no effective treatmentcurrently available. Of this AD population, those suffering from late-onsetAlzheimer’s Disease (LOAD) represent the largest subset of dementiapatients. Unfortunately, current animal models do not fully recapitulate LOAD,thus are not ideal for therapy development. If progress is to be made in thepursuit to cure AD, researchers and clinicians require better resources tounderstand this heterogenous pathology. Thus, the Model OrganismDevelopment and Evaluation for Late-onset AD consortium (MODEL-AD) ischarged with creating, defining, and distributing novel mouse models of LOADcarrying human-relevant risk factors for broad use. Characterization of thesevariants in aging mice will reveal more appropriate disease pathways useful inthe treatment of LOAD.
RESULTSAs expected, all cohorts displayed increased frailty index scores, a measureof aging and vulnerability, by 24 months however in the absence of additionalenvironmental or genetic risk factors, B6.APOEe4.Trem2*R47H mice did notdisplay penetrant behavioral phenotypes, but did exhibit an increase inmortality. B6.APOEe4.Trem2*R47H and B6J.APOEe4 mice showeddecreased levels of lipoproteins at multiple time points compared to controlmice - an effect of human APOE alleles reported previously. PET datashowed changes in glucose uptake over time in B6.APOEe4.Trem2*R47Hmice, but MRI showed no gross abnormalities of the brain. RNA sequencingrevealed age- and sex-related changes in B6.APOEe4.Trem2*R47H brainsamples compared to controls, as well as a novel splicing event in Trem2 asa result of the R47H mutation. Analysis of 6-month-old animals revealeddifferences in serum metabolite levels and in brain proteomes compared tocontrols. Neuropathology analysis in brain tissue is in progress, as arecytokine panels in brain homogenates and plasma.
CONCLUSIONSThe MODEL-AD consortium has established a new mouse strain to studythe effects of two strong risk factors for LOAD. Characterization of thismodel is ongoing and will serve as a backbone strain for the furtheraddition of LOAD risk alleles to more closely align phenotypes in themouse to outcomes observed in human AD• APOEe4 allele mice showed expected aberrant cholesterol levels.• Age-dependent increases in frailty across all strains, however no
significant differences in working memory.• Phenotypic changes in both brain perfusion and metabolism by 8
months• Decreased survival of B6J.hAT mice at 24 months• In vivo imaging, transcriptomic, histological, and biochemical
analysis continues on all time points
Astrocytes/Microglia Neurons Vascular Integrity Aggregate Clearance
DAPIGFAPIBA1S100B
DAPINeuNCtip2
DAPICD31/LectinFibrinIBA1
DAPIX34LampIBA1
1The Jackson Laboratory, Bar Harbor, Maine; 2Stark Neuroscience Research Institute, Indianapolis, Indiana; 3University of Pittsburgh, Pittsburgh, Pennsylvania; 4Sage Bionetworks, Seattle, Washington; 5University of California, Irvine, California; 6Duke University, Durham, North Carolina; 7Helmholtz University, Berlin, Germany; 8Emory University, Atlanta, Georgia, USA.
Figure 7. Immunohistochemistry pipeline. Brain hemispheres sectioned inseries at 25µm was stained with various antibody combinations, as outlined in thetable above. (Hip.:hippocampus; Ctx.:cortex)
METHODSHumanized APOEe4 and the Trem2*R47H mutation, two prominent geneticrisk factors for LOAD, were inserted into the genome of C57BL/6J mice tocreate the B6.APOEe4.Trem2*R47H model. Cohorts ofB6.APOEe4.Trem2*R47H (with controls) were established at multiple sitesand aged to 4, 8, 12, and 24 months prior to behavioral testing. At the JAXcampus, in vivo behavior and wellness assays measured activity (open fieldand running wheels), frailty, coordination (rotarod), and cognitive ability(spontaneous alternation). Repeated congruently at Indiana University (IU)facilities were in vivo MRI and PET studies using [18F]-FDG and [64Cu]-PTSM. Post-mortem analyses at both sites included blood chemistry, brainimmunohistochemistry, transcriptomics, metabolomics, and proteomics.Analyses of subsequent RNA sequencing data in combination with behavioraland molecular phenotypes has yielded additional insight into thetranscriptional differences influencing animal health.
Neuronal loss
Plaques
Tangles
Gliosis
Cognitive Impairments
Synaptic Loss
Vascular compromise
Transcriptomic analysis
In vivo imaging
4mo 8mo 12mo 24mo
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Figure 1. Blood biochemistry profiling. Non-fasted blood was taken at harvest frommice receiving normal diet. Serum was separated and profiled for analytes (low-density lipoprotein shown). (Age-dependent differences within genotype determinedby ANOVA: *p<0.05; **p<0.01; ***p<0.001.)
Figure 2. Assessment of frailty and working memory. Health assessment,measured by frailty assay (left), and hippocampal working memory, as measured bypercent spontaneous alternations in a continuous alternation y-maze task (right).(Age-dependent differences within genotype determined by ANOVA: *p<0.05;**p<0.01; ***p<0.001.)
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4mo, 5xFADnull, F4mo, R47H 4mo, 4/4 4mo, A/T24mo, 5xFADnull, F24mo, R47H24mo, 4/424mo, A/T0
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Figure 3. Male mice expressing human both APOE4 and Trem2*R47H alleles aremore likely to succumb by 24 months of age than C57BL/6J counterparts.Survival of unaffected animals comprising the 24 month cross-sectional cohort.Statistical differences in morbidity determined by log-rank test.
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C57B L/6 J APOE4 TREM 2*R47H APOE4 .TR EM 2*R47H
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Figure 4. In vivo neuroimaging of aged mice reveals variations in regionalglucose metabolism due to changes in expression of APOE4 and Trem2*R47Hrisk alleles at 12 months. Positron emission tomography (PET; red scale) ofradioactive 18F-FDG marker was used to measure tissue glucose uptake, guided bymagnetic resonance imaging (MRI) (black and white) mapping to brain regions ofinterest, indicated by bregma coordinates (far left). Intensity of PET signal in brainsregions, normalized to cerebellum, are quantified. Post-mortem autoradiography ofcoronal brain tissue is represented (rainbow; far right). Genotype-dependentdifferences determined by ANOVA: *p<0.05; **p<0.01; ***p<0.001.
Plaques/Tau Additional
ThiosAPPAT8
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Figure 5. Transcription profiles of LOAD mice carrying APOE4 and Trem2*R47H risk alleles. PCA analysis of transcriptomic data from all subjects at 4, 8, 12, and 24 months.
4 months 8 months 12 months 24 months
Figure 6. Metabolomic and proteomic analysis of blood serum and braintissue. PCA analysis of analyte levels found in the blood serum and brain tissueof C57BL6/J, 5xFAD, and B6.APOEe4.Trem2*R47H (hAT) female and male miceat 6 months of age.
BRAIN METABOLOMESSERUM METABOLOMES
B6 F B6 M 5xFAD F 5xFAD M hAT F hAT M
BRAIN PROTEOMES
AcknowledgementsMODEL-AD was established with funding from The National Institute on Aging (U54 AG054345-01, U54 AG054349-01). Aging studies are also supported by the Nathan Shock Center of Excellence in the Basic Biology of Aging (NIH P30 AG0380770).