Untargeted metabolomics identifies trimethyllysine, a TMAO-producing nutrient precursor, as a predictor of incident cardiovascular disease risk
Xinmin S. Li, Zeneng Wang, Tomas Cajka, Jennifer A. Buffa, Ina Nemet, Alex G. Hurd, Xiaodong Gu, Sarah M. Skye, Adam B. Roberts, Yuping Wu, Lin Li, Christopher J. Shahen, Matthew A. Wagner, Jaana A. Hartiala, Robert L. Kerby, Kymberleigh A. Romano, Yi Han, Slayman Obeid, Thomas F. Lüscher, Hooman Allayee, Federico E. Rey, Joseph A. DiDonato, Oliver Fiehn, W.H. Wilson Tang, Stanley L. Hazen
Xinmin S. Li, Zeneng Wang, Tomas Cajka, Jennifer A. Buffa, Ina Nemet, Alex G. Hurd, Xiaodong Gu, Sarah M. Skye, Adam B. Roberts, Yuping Wu, Lin Li, Christopher J. Shahen, Matthew A. Wagner, Jaana A. Hartiala, Robert L. Kerby, Kymberleigh A. Romano, Yi Han, Slayman Obeid, Thomas F. Lüscher, Hooman Allayee, Federico E. Rey, Joseph A. DiDonato, Oliver Fiehn, W.H. Wilson Tang, Stanley L. Hazen
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Research Article Cardiology Vascular biology

Untargeted metabolomics identifies trimethyllysine, a TMAO-producing nutrient precursor, as a predictor of incident cardiovascular disease risk

Abstract

Using an untargeted metabolomics approach in initial (N = 99 subjects) and replication cohorts (N = 1,162), we discovered and structurally identified a plasma metabolite associated with cardiovascular disease (CVD) risks, N6,N6,N6-trimethyl-L-lysine (trimethyllysine, TML). Stable-isotope-dilution tandem mass spectrometry analyses of an independent validation cohort (N = 2,140) confirmed TML levels are independently associated with incident (3-year) major adverse cardiovascular event risks (hazards ratio [HR], 2.4; 95% CI, 1.7–3.4) and incident (5-year) mortality risk (HR, 2.9; 95% CI, 2.0–4.2). Genome-wide association studies identified several suggestive loci for TML levels, but none reached genome-wide significance; and d9(trimethyl)-TML isotope tracer studies confirmed TML can serve as a nutrient precursor for gut microbiota–dependent generation of trimethylamine (TMA) and the atherogenic metabolite trimethylamine N-oxide (TMAO). Although TML was shown to be abundant in both plant- and animal-derived foods, mouse and human fecal cultures (omnivores and vegans) showed slow conversion of TML to TMA. Furthermore, unlike chronic dietary choline, TML supplementation in mice failed to elevate plasma TMAO or heighten thrombosis potential in vivo. Thus, TML is identified as a strong predictor of incident CVD risks in subjects and to serve as a dietary precursor for gut microbiota–dependent generation of TMAO; however, TML does not appear to be a major microbial source for TMAO generation in vivo.

Authors

Xinmin S. Li, Zeneng Wang, Tomas Cajka, Jennifer A. Buffa, Ina Nemet, Alex G. Hurd, Xiaodong Gu, Sarah M. Skye, Adam B. Roberts, Yuping Wu, Lin Li, Christopher J. Shahen, Matthew A. Wagner, Jaana A. Hartiala, Robert L. Kerby, Kymberleigh A. Romano, Yi Han, Slayman Obeid, Thomas F. Lüscher, Hooman Allayee, Federico E. Rey, Joseph A. DiDonato, Oliver Fiehn, W.H. Wilson Tang, Stanley L. Hazen

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Figure 7

Impact of TML- versus choline-supplemented diet on plasma levels of TML and TMAO, and in vivo thrombosis potential.

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Impact of TML- versus choline-supplemented diet on plasma levels of TML ...
Groups of mice (N = 15) were placed on chemically defined diets supplemented with either 1% trimethyllysine (TML) (A and B) or 1% choline (C) for 11 days as described under Methods. At the indicated times, plasma levels of trimethylamine N-oxide (TMAO) (A and C) or TML (B) were quantified by stable-isotope-dilution LC-MS/MS. (D) In addition, after 11 days of the indicated diet (N = 10), the impact of supplemental dietary TML versus choline on both TMAO levels and in vivo thrombosis potential, as monitored using the FeCl3 carotid artery injury model, was determined as described under Methods. Plasma levels of metabolites after 11 days of the indicated diets were as follows: for 1% TML group, TMAO =4.5 ± 0.7 μM, TML = 37.0 ± 4.9 μM. For 1% choline group, TMAO = 90.6 ± 19.5 μM, TML = 0.8 ± 0.1 μM. For chemically defined chow group, TMAO= 2.6 ± 0.4 μM; TML = 0.9 ± 0.2 μM. Student’s t test (2 tailed) was used to examine the difference between groups. All data are presented as mean ± standard error.