Abstract 3268: Associations of plasma trimethylamine N-oxide (TMAO), choline, and betaine with the gut microbiome and biomarkers of inflammation and cardiometabolic risk in the Multiethnic Cohort
Authors: Fu Benjamin C. , Hullar Meredith AJ , Randolph Timothy W. , Franke Adrian A. , Monroe Kristine R. , Cheng Iona , Wilkens Lynne R. , Shepherd John , Marchand Loïc Le , Lim Unhee , Lampe Johanna W. 
Published: August 2018

Abstract
Background: TMAO is produced by gut microbial metabolism of dietary quaternary amines and has been linked to several chronic diseases, including colorectal cancer and cardiovascular disease. However, the microbes and mechanisms involved are still unclear. Here, we aimed to 1) identify microbial taxa associated with TMAO and 2) evaluate associations of plasma TMAO, along with its precursors choline and betaine, with inflammatory and cardiometabolic biomarkers.
Methods: We conducted a cross-sectional analysis in 1,716 participants (men and women, 60-77, and of 5 racial/ethnic groups) of the Adiposity Phenotype Study within the Multiethnic Cohort in Hawaii and California. Plasma TMAO, choline, and betaine were measured by LC-MS/MS. The gut microbiome was analyzed by Illumina MiSeq paired-end sequencing of the 16S rRNA gene V1-V3 region using DNA extracted from stool. Fasting blood was analyzed for lipopolysaccharide-binding protein (LBP) and insulin by ELISA; C-reactive protein (CRP), cholesterol, glucose, and triglycerides using a Cobas autoanalyzer; and HOMA-IR for insulin resistance by derivation. Associations between microbial genera and TMAO were assessed with negative binomial and zero-inflated negative binomial (ZINB) regression models, with control of the false discovery rate (FDR) using the Benjamini-Hochberg procedure. Associations of TMAO, choline, and betaine with biomarkers were determined using multivariable linear regression and a ZINB model for CRP, adjusted for age, sex, race/ethnicity, physical activity, aspirin use, and % body fat.
Results: Of 105 genera examined, 7 were associated with TMAO at an FDR of 0.01: Streptoccoccus, Blautia, Clostridium, a genus from the Ruminococcaceae family, Butyricimonas, Lactobacillus, and an uncultured Verrucomicrobia of the order vadinHA64; all showed a positive relationship. Plasma choline (β±SE: 0.23±0.10; p=0.03) and betaine (0.19±0.08; p=0.02), but not TMAO, were positively associated with CRP, whereas only choline was associated with LBP (1.97±0.80; p=0.01). Choline was inversely associated with HDL cholesterol (-14.86±2.29; p&lt;0.001) and positively associated with LDL cholesterol (9.86±5.01; p=0.049). Betaine (-0.16±0.03; p&lt;0.001) and choline (0.14±0.05; p=0.002) were associated with triglycerides, while TMAO was not (0.01±0.02; p=0.46). All 3 plasma compounds were associated with HOMA-IR, with only betaine having an inverse association (-0.32±0.06; p=0.004).
Conclusion: We found several genera of gut microbes associated with plasma TMAO, including Clostridium, several species of which can metabolize choline to trimethylamine. We also identified associations between plasma TMAO, choline, and betaine with inflammatory and cardiometabolic markers, particularly choline, which indicated risk to adverse health outcomes.
Citation Format: Benjamin C. Fu, Meredith AJ Hullar, Timothy W. Randolph, Adrian A. Franke, Kristine R. Monroe, Iona Cheng, Lynne R. Wilkens, John Shepherd, Loïc Le Marchand, Unhee Lim, Johanna W. Lampe. Associations of plasma trimethylamine N-oxide (TMAO), choline, and betaine with the gut microbiome and biomarkers of inflammation and cardiometabolic risk in the Multiethnic Cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3268.