Dietary choline content and hdl levels modulate gut microbiota composition and contribute to a pro-atherogenic plasma metabolomic profile in mice

Background and Aims: Gut microbiota can influence atherosclerosis development by metabolizing dietary choline: experimental and observational studies have highlighted a positive correlation between increased plasma choline-derived TMAO concentrations and adverse cardiovascular events. This study was aimed at investigating how the plasma metabolome of mice prone to atherosclerosis development was modulated by HDL levels and the dietary intake of choline. Methods: Low-fat, no cholesterol diets with different choline content (0.09% or 1.2%) were administered for 16 weeks to two groups of atherosclerosis-prone female mice: 1) extremely low-HDL mice, deficient for both murine apoA-I and apoE (DKO); 2) high-HDL mice, deficient for both apoA- I/apoE, but overexpressing human apoA-I (DKO/hA-I). At sacrifice, atherosclerosis was evaluated, and a targeted metabolomics of plasma was performed. Results: The high-choline diet increased the proportion of Proteobacteria (mainly Burkholderiaceae). and decreased that of Rikenellaceae only in DKO mice. Surprisingly, although the high-choline diet resulted into elevated plasma TMAO levels in both genotypes, choline supplementation significantly worsened plaque development only in DKO/hA-I mice. Noteworthy, only in DKO/hA-I mice, high-choline diet led to an increased concentration of plasma lipids (triglycerides, hexosylceramides, ceramides and sphingomyelins), as well as several markers of increased cardiovascular disease risk and compromised renal function such as asymmetric dimethylarginine, symmetric dimethylarginine, indoxyl sulfate, creatinine and the microbiota-derived metabolite phenylacetylglutamine. Conclusions: In conclusion, dietary choline supplementation modifies gut microbiota composition and atherosclerosis development. Plasma metabolomics clearly indicated that choline supplementation, only in the presence of HDL, increases the concentration of several metabolites indicative of augmented cardiovascular risk and impaired kidney function.