Anti-atherogenic diets alter gut microbiome in experimental mice

Diets and lifestyle significantly contribute to risk factors for atherosclerotic vascular disease. Diets with cholesterol-lowering and antioxidant properties have been shown to prevent atherogenesis in experimental animals. Our laboratory has reported significant antiatherogenic effects of various functional foods including wild rice, kgengwe seeds, and phytosterols. We hypothesized that anti-atherogenic properties of the above-mentioned diets may be mediated through alterations in the diversity and populations of the gut microbiome in LDL-receptor knockout mice (n=10 for each group) over 16 weeks of study course. Fecal samples of the treated mice and control mice were collected at weeks 0, 4, and 16. Bacterial 16S rDNA was extracted from the fecal samples and used to generate an amplified library for Illumina MiSeq sequencing. The representative sequence of each cluster was selected to represent the operational taxonomy unit (OTU) for downstream diversity, taxonomy, and differential expression analyses. Alpha and beta diversity analyses were performed followed by sample clustering to determine the top 20 taxa. The taxonomic annotation of each OTU was performed by mapping representative tags with ribosomal database project and NT-16S microbial databases, where these data were used to plot taxa heatmaps. Our data show that the diets had impacted the number and diversity of fecal bacteria. For example, at the end of the study uncultured Anaeroplasma sp.(OTU104999)16SrDNAsequencesweredetectedat100-fold greater quantities in wild-rice treated animals as compared to nontreated control animals. Similarly, Ileibacterium valens (OTU36) was 6-foldhigherinphytosterol-treatedmicefecesascomparedtocontrol animals. On the other hand, the control animals had approximately 10 times more unclassified Porphylomonadaceae sp. (OTU728) as compared to phytosterol-treated animals. These results suggest that antiatherogenic effects of diets may be mediated through alterations in the gut microbiome. Correlative studies are in progress to define the relationship between the abundance of various bacterial species and the severity of atherosclerotic lesions. Additional studies are being designed to determine how the aforementioned diet-induced changes in bacterial diversity and population impact atherogenesis in mice.

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