COMPARING THE IMPACT OF BLUEBERRY CULTIVARS WITH DIFFERENT LEVELS OF CHLOROGENIC ACID ON TRIMETHYLAMINE-N OXIDE PRODUCTION AND ITS ASSOCIATED METABOLIC COMPLICATIONS

Cardiovascular disease (CVD) causes ~32% of deaths worldwide. There is an urgent need to develop complementary strategies across diet, lifestyle, and medicine to reduce CVD incidence and burden. Elevated blood trimethylamine N-oxide (TMAO) concentrations increase atherosclerosis risk. TMAO is formed through a microbial-host axis involving release of trimethylamine (TMA) from choline by specific gut bacteria containing the cutC/D gene cluster, which encodes choline TMA lyase. TMA is absorbed into the circulation and then oxidized to TMAO by hepatic flavin-containing monooxygenase 3 (FMO3). TMAO is thought to promote the development of atherosclerosis. There is no FDA-approved drug to lower TMAO levels, underscoring the need for complementary strategies to manage TMAO production. Interest is emerging in the TMAO-lowering activities of dietary phenolics. Phenolics may reduce TMAO levels by reducing the abundance of bacterial genera that convert choline to TMA, or direct inhibition of TMA lyase. Through our ex vivo-in vitro anaerobic fecal fermentation and in vivo mouse studies, we identified chlorogenic acid (CGA) as a TMA production inhibitor. Blueberries are rich in CGA and have known cardioprotective benefits. CGA has been evaluated as a TMA/TMAO production inhibitor in a few pre-clinical studies. Our preliminary data indicate that CGA inhibits choline conversion to TMA in a dose-dependent manner. Importantly, levels of CGA vary widely across blueberry cultivars, but it is unknown whether variation in CGA level contributes to different TMAO-lowering and cardioprotective activities from blueberries. Further data are required to confirm the potential of CGA-rich blueberries as TMA/TMAO production inhibitors in vivo and to determine if more CGA content imparts greater activity. To advance our ability to employ CGA-rich blueberries to lower circulating TMAO and reduce atherosclerosis risk, it is critical that we determine whether CGA levels in blueberries determine their efficacy and elucidate the mechanism(s) by which this occursOur overall objective is to evaluate whether CGA is a key bioactive that enables blueberries to inhibit formation of the pro-atherogenic gut microbial metabolite TMAO (and its precursor, TMA) when consumed. Our central hypothesis is that CGA content is a primary determinant of the TMAO-lowering benefits of blueberries. Our specific objectives are to:Determine if blueberry CGA content predicts reduced TMAO formation and atherosclerosis when cultivars with >10-fold difference in CGA are administered to rodents;Determine whether CGA content correlates with reduced TMA production in multiple blueberry accessions from a genetic diversity population with a large spread of CGA in our ex vivo-in vitro human fecal fermentation model; andElucidate mechanism(s) by which CGA and CGA-rich blueberries modulate TMA formation in the gut using isolated bacteria known to carry cutC/D.