Just like how certain foods can interact with our genes to affect our health, a recent study found that specific genetic variants combined with a high fat/high sugar diet (HFD) can accelerate Alzheimer’s disease (AD) in mice. While previous studies mainly focused on early-onset AD models, this research investigated late-onset AD (LOAD) by introducing genetic risk factors into mouse models. The study created three different mouse models with genetic variants associated with AD and fed them either an HFD or a control diet. The results showed that mice with the Plcg2M28L variant in the phospholipase C Gamma 2 gene, when fed an HFD, exhibited increased weight gain, altered glucose utilization and brain perfusion, and increased microglia density. These changes were not observed in mice with other genetic variants or mice on a control diet. Interestingly, the Plcg2M28L mice also showed gene expression patterns similar to those found in humans with AD. This study highlights the importance of considering both genetic factors and diet when studying the impact of obesity on AD progression.

Obesity is recognized as a significant risk factor for Alzheimer’s disease (AD). Studies have supported the notion that obesity accelerates AD-related pathophysiology in mouse models of AD. The majority of studies, to date, have focused on the use of early-onset AD models. Here, we evaluate the impact of genetic risk factors on late-onset AD (LOAD) in mice fed with a high fat/high sugar diet (HFD). We focused on three mouse models created through the IU/JAX/PITT MODEL-AD Center. These included a combined risk model with APOE4 and a variant in triggering receptor expressed on myeloid cells 2 (Trem2R47H). We have termed this model, LOAD1. Additional variants including the M28L variant in phospholipase C Gamma 2 (Plcg2M28L) and the 677C > T variant in methylenetetrahydrofolate reductase (Mthfr677C >T) were engineered by CRISPR onto LOAD1 to generate LOAD1.Plcg2M28L and LOAD1.Mthfr677C >T. At 2 months of age, animals were placed on an HFD that induces obesity or a control diet (CD), until 12 months of age. Throughout the study, blood was collected to assess the levels of cholesterol and glucose. Positron emission tomography/computed tomography (PET/CT) was completed prior to sacrifice to image for glucose utilization and brain perfusion. After the completion of the study, blood and brains were collected for analysis. As expected, animals fed a HFD, showed a significant increase in body weight compared to those fed a CD. Glucose increased as a function of HFD in females only with cholesterol increasing in both sexes. Interestingly, LOAD1.Plcg2M28L demonstrated an increase in microglia density and alterations in regional brain glucose and perfusion on HFD. These changes were not observed in LOAD1 or LOAD1.Mthfr677C >T animals fed with HFD. Furthermore, LOAD1.Plcg2M28L but not LOAD1.Mthfr677C >T or LOAD1 animals showed transcriptomics correlations with human AD modules. Our results show that HFD affects the brain in a genotype-specific manner. Further insight into this process may have significant implications for the development of lifestyle interventions for the treatment of AD.

Read Full Article (External Site)