thromboplastin and trimethyloxamine

Gut microbiota and their generated metabolites impact the host vascular phenotype. The metaorganismal metabolite trimethylamine N-oxide (TMAO) is both associated with adverse clinical thromboembolic events, and enhances platelet responsiveness in subjects. The impact of TMAO on vascular Tissue Factor (TF) in vivo is unknown. Here, we explore whether TMAO-enhanced thrombosis potential extends beyond TMAO effects on platelets, and is linked to TF. We also further explore the links between gut microbiota and vascular endothelial TF expression in vivo.. In initial exploratory clinical studies, we observed that among sequential stable subjects (n = 2989) on anti-platelet therapy undergoing elective diagnostic cardiovascular evaluation at a single-site referral centre, TMAO levels were associated with an increased incident (3 years) risk for major adverse cardiovascular events (MACE) (myocardial infarction, stroke, or death) [4th quartile (Q4) vs. Q1 adjusted hazard ratio (HR) 95% confidence interval (95% CI), 1.73 (1.25-2.38)]. Similar results were observed within subjects on aspirin mono-therapy during follow-up [adjusted HR (95% CI) 1.75 (1.25-2.44), n = 2793]. Leveraging access to a second higher risk cohort with previously reported TMAO data and monitoring of anti-platelet medication use, we also observed a strong association between TMAO and incident (1 year) MACE risk in the multi-site Swiss Acute Coronary Syndromes Cohort, focusing on the subset (n = 1469) on chronic dual anti-platelet therapy during follow-up [adjusted HR (95% CI) 1.70 (1.08-2.69)]. These collective clinical data suggest that the thrombosis-associated effects of TMAO may be mediated by cells/factors that are not inhibited by anti-platelet therapy. To test this, we first observed in human microvascular endothelial cells that TMAO dose-dependently induced expression of TF and vascular cell adhesion molecule (VCAM)1. In mouse studies, we observed that TMAO-enhanced aortic TF and VCAM1 mRNA and protein expression, which upon immunolocalization studies, was shown to co-localize with vascular endothelial cells. Finally, in arterial injury mouse models, TMAO-dependent enhancement of in vivo TF expression and thrombogenicity were abrogated by either a TF-inhibitory antibody or a mechanism-based microbial choline TMA-lyase inhibitor (fluoromethylcholine).. Endothelial TF contributes to TMAO-related arterial thrombosis potential, and can be specifically blocked by targeted non-lethal inhibition of gut microbial choline TMA-lyase.

Topics: Animals; Choline; Endothelial Cells; Humans; Lyases; Methylamines; Mice; Thromboplastin; Thrombosis

Trimethylamine-N-oxide (TMAO), one of the products in choline metabolite, is recently reported to be associated with cardiovascular diseases (CVD) that mainly attribute to atherothrombosis. However, the mechanisms how TMAO functions in the pathogenesis of CVD and atherothrombosis remain elusive. Tissue factor (TF) has been implicated in the thrombogenicity of atherosclerotic plaques. In the present study, we demonstrated that TMAO promoted TF (but not TF pathway inhibitor) expression via activation of NF-κB signaling pathway in primary human coronary artery endothelial cells (HCAECs). TMAO strongly increased TF activity and thrombin production. Further, a small dose of TMAO significantly increased TF expression and nuclear translocation of NF-κB with the synergistic action of low-dose of pro-atherosclerotic factors, such as TNF-α and HMGB1. Importantly, plasma TMAO level was positively correlated with TF activity in patients with ST-elevation myocardial infarction (STEMI). Altogether, our data revealed that TMAO promoted thrombosis through increasing TF expression and activity. The understanding of the new link between TMAO and atherothrombosis may facilitate therapeutic strategy in the prevention and treatment of atherothrombosis.

Topics: Aged; Atherosclerosis; Cells, Cultured; Endothelial Cells; Female; Humans; Male; Methylamines; Middle Aged; Thrombin; Thromboplastin; Thrombosis