Translational potential of JAX humanized APOE mice: Metabolism and body composition in very old mice

• Published in: Alzheimer's & dementia Vol. 18; no. S5
• Main Authors: Bhattrai, Avnish, McLean, John W., Raikes, Adam C., Wiegand, Jean‐Paul L., Skopp, Stacy M, Brinton, Roberta Diaz
• Format: Journal Article
• Language: English
• Published: 01.12.2022
• ISSN: 1552-5260; 1552-5279
• DOI: 10.1002/alz.068128

Background Apolipoprotein (APOE) is the strongest genetic risk factor for the development of late‐onset Alzheimer’s disease (LOAD). Clinically, LOAD exhibits strong sex effects with females being twice at the risk of developing AD than males. Models exhibiting strong AD etiology are used in preclinical settings, however lack of translatability necessitates model development with a reverse translational approach. This study explores metabolic hallmarks of LOAD assessing the clinical translatability of the JAX humanized APOE (hAPOE) mouse model. Method hAPOE mice (M/F, n = 65, mean age = 23.35 +/‐ 0.90 months) with e3/3, e3/4 or e4/4 genotype underwent a metabolic and body composition screening assay including fasting blood glucose (FBG) and ketone (FKB) measurement, EchoMRI, and 18F‐FDG‐PET brain imaging, prior to being sacrificed. Blood plasma was analyzed for triglyceride levels. Cerebral FDG‐PET standardized uptake values were normalized to cerebellum. All data were analyzed with genotype x sex analysis of variance. P ≤ 0.05 was considered statistically significant and post‐hoc pairwise analyses were conducted for interaction effects with p ≤ 0.1 (FKB, adipose index) for future study planning. Result Females had significantly lower lean mass (p < 0.0001) and FBG (p=0.05), with a trend toward lower glucose uptake on FDG‐PET compared to males (p=0.072). Post‐hoc interaction analyses of FKB (interaction p=0.105) demonstrated lower ketone body levels in male e4/4s compared to female e4/4s (uncorrected p=0.0685) and male e3/4s (p=0.034). Post‐hoc interaction analyses of adipose index (interaction p=0.093) demonstrated greater adiposity in female e4/4s compared to male e4/4s (uncorrected p=0.005) and female e3/3s (uncorrected p=0.035). No effects of APOE genotype were observed. Conclusion In a mouse cohort at a comparable human age of ∼ 70 years, lower lean mass, fasting blood glucose, and glucose uptake in the brain for female mice indicates ongoing bioenergetic deficits and is corroborated by observations within clinical populations. Greater adiposity in female e4/4s suggests that brain bioenergetic demand is not being met through fat reserves. However, the overall lack of genotypic effects suggests this bioenergetic crisis is not driven by hAPOE in this animal model, limiting clinical translatability. NIA R01AG057931; University of Arizona TBIR (NIH S10 OD025016).