Impact Of Dietary Choline On Atherosclerosis Development In Conventionally Raised ApoE-KO Mice Expressing Different Levels Of ApoA-I

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. Methods: This study was aimed at investigating, for the first time, how apoA-I/HDL levels can influence atherosclerosis development by modulating gut microbiota composition. Results: Chow diets with different choline contents (0.09% or 1.2%) were administered for 20 weeks to conventionally-raised, atherosclerosis-prone mice expressing different levels of apoA-I: extremely low-HDL mice (A- IKO/EKO) or high-HDL mice, deficient for both murine apoA-I and apoE, but overexpressing human apoA-I (hA-I/A-IKO/EKO). Choline supple- mentation did non influence plasma cholesterol and triglyceride concentrations, that were dramatically reduced in A-IKO/EKO vs hA-I/A-IKO/EKO mice. Atherosclerosis, evaluated at the aortic sinus, was unsurprisingly increased in A-IKO/EKO vs hA-I/A-IKO/EKO mice. Less predictably, choline supplementation significantly worsened plaque development only in hA-I/ A-IKO/EKO mice (66,870\ub146,870 vs 147,360\ub142,750 mm2 in females; 63,691\ub137,432 vs 110,030\ub142,937 mm2 in males). To characterize plaque composition, O.R.O. staining for neutral lipids and Mac-2 specific IHC for macrophages were performed. An increased dietary choline content did not result in an increased deposition of neutral lipids nor of the amount of infiltrating macrophage in atherosclerotic plaques of both genotypes. Conclusions: Our results indicate that dietary choline supplementation worsens atherosclerosis development only when apoA-I is expressed. Further studies are ongoing to better clarify: i) how apoA-I can modulate gut microbiota composition (i.e. the presence of choline-degrading bacteria); ii) the pathophysiological mechanisms influenced by the choline- TMA-TMAO metabolic pathway