Background
The MODEL‐AD Consortium seeks to develop the next generation of Alzheimer’s Disease models based on human data. A popular model of familial AD is the 5xFAD mouse, characterized by early ...amyloid‐β deposition and cognitive decrements. Despite numerous studies, the 5xFAD mouse has not been comprehensively phenotyped for vascular and metabolic features over its lifespan.
Method
Male and female 5xFAD and WT littermates underwent in vivo 18F‐FDG‐PET imaging at 4, 6, and 12 months of age to evaluate regional glucose metabolism. A separate cohort of mice (4, 8, 12 months) underwent “vessel painting” that labels all cerebral vessels with a fluorescent dye. “Vessel painted” brains were analyzed for vascular characteristics such as vessel density, junction density, vessel length, network complexity, number of collaterals and vessel diameter.
Results
Our analyses revealed that vessel length, vessel and junction densities increased from 4 to 12 months on the cortical surface in both 5xFAD and WT mice. The number of collateral vessels between the middle cerebral artery (MCA) and the anterior and posterior cerebral arteries decreased with age but their diameters were significantly increased only in 5xFAD mice. MCA average vessel length was decreased in 5xFAD mice compared to WT. Analysis of 18F‐FDG cortical uptake found significant interactions between WT and 5xFAD mice spanning 4‐12 months of age in retrosplenial, somatosensory and visual cortices. Broadly, 5xFAD males had increased 18F‐FDG uptake at 12 months of age compared to WT mice. In most cortical regions, female 5xFAD mice had reduced FDG uptake compared to WT across the lifespan. In males these metabolic increases coincided with decreased vessel characteristics.
Conclusion
The 5xFAD mouse exhibits AD‐like cognitive deficits with age that are associated with increasing amyloid‐β deposition. No significant differences were found in cortical vascular features although males and females exhibited opposite effects in 18F‐FDG uptake. The MCA supplies blood to large portions of the motor cortex and increased vessel lengths and decreased collaterals along with higher metabolic rates in 5xFAD mice may be related to increasing behavioral deficits via metabolic insufficiency or other mechanisms.
Background
The MODEL‐AD Consortium seeks to develop the next generation of Alzheimer’s Disease models based on human data. A popular model of familial AD is the 5xFAD mouse, characterized by early ...amyloid‐ß deposition and cognitive decrements. Despite numerous studies, the 5xFAD mouse has not been comprehensively phenotyped for vascular and metabolic features over its lifespan.
Method
Male and female 5xFAD and WT littermates underwent in vivo 18F‐FDG‐PET imaging at 4, 6, and 12 months of age to evaluate regional glucose metabolism. A separate cohort of mice (4, 8, 12 months) underwent “vessel painting” that labels all cerebral vessels with a fluorescent dye. “Vessel painted” brains were analyzed for vascular characteristics such as vessel density, junction density, vessel length, network complexity, number of collaterals and vessel diameter.
Result
Our analyses revealed that vessel length, vessel and junction densities increased from 4 to 12 months on the cortical surface in both 5xFAD and WT mice. The number of collateral vessels between the middle cerebral artery (MCA) and the anterior and posterior cerebral arteries decreased with age but their diameters were significantly increased only in 5xFAD mice. MCA average vessel length was decreased in 5xFAD mice compared to WT. Analysis of 18F‐FDG cortical uptake found significant interactions between WT and 5xFAD mice spanning 4‐12 months of age in retrosplenial, somatosensory and visual cortices. Broadly, 5xFAD males had increased 18F‐FDG uptake at 12 months of age compared to WT mice. In most cortical regions, female 5xFAD mice had reduced FDG uptake compared to WT across the lifespan. In males these metabolic increases coincided with decreased vessel characteristics.
Conclusion
The 5xFAD mouse exhibits AD‐like cognitive deficits with age that are associated with increasing amyloid‐ß deposition. No significant differences were found in cortical vascular features although males and females exhibited opposite effects in 18F‐FDG uptake. The MCA supplies blood to large portions of the motor cortex and increased vessel lengths and decreased collaterals along with higher metabolic rates in 5xFAD mice may be related to increasing behavioral deficits via metabolic insufficiency or other mechanisms.
Background
MODEL‐AD has developed and characterized novel mouse models that aim to better phenocopy human LOAD for preclinical testing. More than 40 different models carrying combinations of LOAD ...risk factors have been created and assessed for relevance to LOAD. In this study, we aim to determine the mechanisms by which variations in the phospholipase C gamma 2 (PLCG2) gene increase risk for LOAD.
Methods
The M28L variant in PLCG2 (PLCG2*M28L) was prioritized as a LOAD risk factor. Mice were generated by CRISPR/CAS9 introduction of Plcg2*M28L variant on to LOAD1 (B6.APOE4.Trem2*R47H) and transcriptional profiling of brain hemispheres from 12 months old mice was used to evaluate molecular effects of Plcg2*M28L. To evaluate the contribution of Plcg2*M28L to LOAD risk, mice where placed on control or high fat diet (HFD) to serve as an environmental driver of neuroinflammation. Female and male LOAD1.Plcg2*M28L and LOAD1 control mice are being characterized at 4 and 12 mos through the MODEL‐AD phenotyping pipeline, which includes in vivo imaging of brain perfusion and glycolytic metabolism, multi‐omics, fluid biomarkers, cognition, and neuropathology.
Results
LOAD1.Plcg2*M28L mice showed brain transcriptomic alignment at 12 mos to human LOAD, and was prioritized for deep phenotyping. LOAD1 mice on HFD showed significant regional reductions in brain glycolysis and increased perfusion relative to controls yielding an uncoupled phenotype. By contrast, LOAD1.Plcg2*M28L mice showed a little to no regional changes in brain glycolysis or perfusion and few uncoupled regions. Multi‐resolution connectomics revealed a decrease in cluster number and organization in LOAD1 but not LOAD1.Plcg2*M28L for both sexes fed HFD compared with control diets. By 12 mos, male and female LOAD1.Plcg2*M28L mice on HFD showed opposite changes in clustering coefficient, network degree, and network density, with males showing a decrease and females an increase relative to controls. Mice carrying Plcg2*M28L variants are also being phenotyping at 18 and 24 mos.
Conclusions
Data collected to date reveal Plcg2*M28L on a LOAD1 background showed fewer sex‐dependent change in metabolism, perfusion and uncoupling on HFD when compared to LOAD1. These data suggest that the Plcg2*M28L risk variant on the LOAD1 background may result in an attenuated TREM2 signaling.
We assessed the accuracy of semi-automated tumor volume maps of plexiform neurofibroma (PN) generated by a deep neural network, compared to manual segmentation using diffusion weighted imaging (DWI) ...data. NF1 Patients were recruited from a phase II clinical trial for the treatment of PN. Multiple b-value DWI was imaged over the largest PN. All DWI datasets were registered and intensity normalized prior to segmentation with a multi-spectral neural network classifier (MSNN). Manual volumes of PN were performed on 3D-T2 images registered to diffusion images and compared to MSNN volumes with the Sørensen-Dice coefficient. Intravoxel incoherent motion (IVIM) parameters were calculated from resulting volumes. 35 MRI scans were included from 14 subjects. Sørensen-Dice coefficient between the semi-automated and manual segmentation was 0.77 ± 0.016. Perfusion fraction (f) was significantly higher for tumor versus normal tissue (0.47 ± 0.42 vs. 0.30 ± 0.22, p = 0.02), similarly, true diffusion (D) was significantly higher for PN tumor versus normal (0.0018 ± 0.0003 vs. 0.0012 ± 0.0002, p < 0.0001). By contrast, the pseudodiffusion coefficient (D*) was significantly lower for PN tumor versus normal (0.024 ± 0.01 vs. 0.031 ± 0.005, p < 0.0001). Volumes generated by a neural network from multiple diffusion data on PNs demonstrated good correlation with manual volumes. IVIM analysis of multiple b-value diffusion data demonstrates significant differences between PN and normal tissue.
Endovascular stent grafting of abdominal aortic aneurysms is a new technique that may replace open surgery in selected cases. Pre-and postoperative angiography can be replaced by helical CT. This ...pictorial essay describes and illustrates the use of multislice helical CT where maximum intensity projection and multiplanar reformats play a central role in the evaluation.
Background
Alzheimer’s disease (AD) is the most common cause of dementia in the United States. Approximately 95% of patients have sporadic Late‐Onset AD (LOAD) which lacks an inheritance pattern. ...Therefore, identifying phenotypic patterns is critical for understanding disease progression.
Among all the genetic markers which being identified as AD risks, and APOE4 confers the strongest one. The GWAS analysis also revealed a LOAD‐associated locus on the gene of TREM2. As the microglial receptor of APOE, the R47H variant on TREM2 increases the AD risk. In this study, how these risk alleles affect the brain phenotypes were assessed by MODEL‐AD.
Method
We established an analytical scheme which elucidates the cerebral perfusion and metabolism profiles across 27 brain regions by using 64Cu‐PTSM and 18F‐FDG PET imaging platform in the mice with wild‐type, humanized APOE3 (hAPOε3/ ε3), humanized APOE4 (hAPOε4/ ε4), TREM2 risk (Trem2R47H/R47H), and doubled risks (hAPOε4/ ε4:Trem2R47H/R47H) alleles.
Also, RNA‐seq results from the hemisphere samples were used to conduct the correlation between PET measurements and the gene expression changes from each animal cohort.
Result
Longitudinal analysis (4mo animals as reference) revealed aging effects in each cohort. The male hAPOE4 mice and both sexes of Trem2 risk animals had hypo‐perfusion and metabolism, while female hAPOE4 mice showed an uncoupled hyper‐perfusion and hypo‐metabolism phenotype. In the doubled risks mice, perfusion and metabolism showed a mixed regional‐dependent phenotype.
Cross‐sectional analysis (wildtype mice as reference) showed the effects of humanized genes. A reduction in glucose metabolism was discovered. Intriguingly, male risks mice also showed reduced in perfusion, while the female mice showed a metabolic uncoupling profile.
Cross‐sectional analysis (hAPOE3 mice as reference) showed the effects of risk alleles. An overall reduction in both perfusion and metabolism was discovered in all animal cohorts.
To confirm these findings, RNAseq showed the genes involved in cerebral perfusion, glucose transportation, and metabolism regulation were altered, which are consistent with the findings.
Conclusion
These data suggest that the new perfusion‐metabolism strategy may help to identify AD‐related patterns. Moreover, they replicate clinical manifestations of subjects with the same variants. Finally, additional studies are needed to elucidate the mechanisms and etiology of this uncoupling phenomenon.
INTRODUCTION
MODEL‐AD (Model Organism Development and Evaluation for Late‐Onset Alzheimer's Disease) is creating and distributing novel mouse models with humanized, clinically relevant genetic risk ...factors to capture the trajectory and progression of late‐onset Alzheimer's disease (LOAD) more accurately.
METHODS
We created the LOAD2 model by combining apolipoprotein E4 (APOE4), Trem2*R47H, and humanized amyloid‐beta (Aβ). Mice were subjected to a control diet or a high‐fat/high‐sugar diet (LOAD2+HFD). We assessed disease‐relevant outcome measures in plasma and brain including neuroinflammation, Aβ, neurodegeneration, neuroimaging, and multi‐omics.
RESULTS
By 18 months, LOAD2+HFD mice exhibited sex‐specific neuron loss, elevated insoluble brain Aβ42, increased plasma neurofilament light chain (NfL), and altered gene/protein expression related to lipid metabolism and synaptic function. Imaging showed reductions in brain volume and neurovascular uncoupling. Deficits in acquiring touchscreen‐based cognitive tasks were observed.
DISCUSSION
The comprehensive characterization of LOAD2+HFD mice reveals that this model is important for preclinical studies seeking to understand disease trajectory and progression of LOAD prior to or independent of amyloid plaques and tau tangles.
Highlights
By 18 months, unlike control mice (e.g., LOAD2 mice fed a control diet, CD), LOAD2+HFD mice presented subtle but significant loss of neurons in the cortex, elevated levels of insoluble Ab42 in the brain, and increased plasma neurofilament light chain (NfL).
Transcriptomics and proteomics showed changes in gene/proteins relating to a variety of disease‐relevant processes including lipid metabolism and synaptic function.
In vivo imaging revealed an age‐dependent reduction in brain region volume (MRI) and neurovascular uncoupling (PET/CT).
LOAD2+HFD mice also demonstrated deficits in acquisition of touchscreen‐based cognitive tasks.
Background. The purpose of the present study was to determine the natural history of coronary artery and aorta calcification by spiral computed tomography (CT) in patients who undergo a renal ...transplant and patients on haemodialysis. Methods. Two cohorts were evaluated for the natural history of vascular calcification: (i) 23 patients who underwent a baseline CT scan at the time of renal transplant and a repeat evaluation 15–20 months later; and (ii) 33 chronic kidney disease, stage 5 haemodialysis subjects who underwent a baseline CT scan, all followed for a minimum of 15 months, and 17 of whom underwent a second CT scan. Results. In the patients undergoing a renal transplant, there was no net change in CAC with time, suggesting stabilization of calcification. In the haemodialysis patients, the median CAC increased by 1.27±1.88 score/days, P = 0.013. There was a trend towards increasing AoC score in both groups. All patients without calcification at baseline remained calcification free at follow-up. In the 15 months following baseline, the six dialysis patients who died had a significantly greater CAC score at baseline compared with the 24 patients who remained alive. Similarly, those patients who were hospitalized had a greater baseline CAC than patients who were not hospitalized. Conclusion. In this preliminary study, renal transplantation appears to slow down or arrest CAC, whereas CAC progresses in haemodialysis patients. In haemodialysis patients, CAC was greater in patients who died or were hospitalized compared with those who remained alive or were not hospitalized.
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