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Evans M, Dai L, Avesani CM, Kublickiene K, Stenvinkel P. The dietary source of trimethylamine N-oxide and clinical outcomes: an unexpected liaison. Clin Kidney J 2023; 16:1804-1812. [PMID: 37915930 PMCID: PMC10616480 DOI: 10.1093/ckj/sfad095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Indexed: 11/03/2023] Open
Abstract
The profile of gut microbiota can vary according to host genetic and dietary characteristics, and be influenced by disease state and environmental stressors. The uremic dysbiosis results in a loss of biodiversity and overgrowth of microorganisms that may cause elevation of metabolic solutes such as trimethylamine N-oxide (TMAO), inducing pathogenic effects on its host. In patients with chronic kidney disease (CKD), TMAO levels are elevated because of a decreased clearance and an increased production from the uremic gut dysbiosis with a disrupted intestinal barrier and elevated enzymatic hepatic activity. Dietary precursors of TMAO are abundant in animal-derived foods such as red meat, egg yolk and other full-fat dietary products. TMAO is also found naturally in fish and certain types of seafood, with the TMAO content highly variable according to the depth of the sea where the fish is caught, as well as processing and storage. Although evidence points towards TMAO as being an important link to vascular damage and adverse cardiovascular outcomes, the evidence in CKD patients has not been consistent. In this review we discuss the potential dietary sources of TMAO and its actions on the intestinal microbiome as an explanation for the divergent results. We further highlight the potential of a healthy diet as one feasible therapeutic opportunity to prevent gut dysbiosis and reduce uremic toxin levels in patients with CKD.
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Affiliation(s)
- Marie Evans
- Renal Unit, Department of Clinical Sciences and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden
| | - Lu Dai
- Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Carla Maria Avesani
- Renal Unit, Department of Clinical Sciences and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden
| | - Karolina Kublickiene
- Renal Unit, Department of Clinical Sciences and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden
| | - Peter Stenvinkel
- Renal Unit, Department of Clinical Sciences and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden
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Florea CM, Baldea I, Rosu R, Moldovan R, Decea N, Filip GA. The Acute Effect of Trimethylamine-N-Oxide on Vascular Function, Oxidative Stress, and Inflammation in Rat Aortic Rings. Cardiovasc Toxicol 2023:10.1007/s12012-023-09794-6. [PMID: 37119388 DOI: 10.1007/s12012-023-09794-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 04/24/2023] [Indexed: 05/01/2023]
Abstract
A growing body of evidence suggests that the gut microbiota affects the cardiovascular system directly and indirectly via biologically active molecules. TMAO, a key metabolite produced by gut bacteria is implicated in atherosclerosis and chronic endothelial dysfunction, but with an unclear effect on vascular tone, oxidative stress, and inflammation. Our study aimed to evaluate the acute effects of TMAO on vascular contractility in relation with oxidative stress markers and inflammation. Aortic rings were harvested from laboratory rats and placed in a tissue bath system containing TMAO in concentrations of 300, 100, 10 µM, and control. Vascular tone under the influence of vasoconstrictor phenylephrine and non-endothelial-dependent vasodilator sodium nitroprusside was assessed using force transducers connected to a computer-based acquisition system. Oxidative stress and inflammation were quantified by vascular assessment of the activity of NF-κB, NRF2, SOD1, and iNOS by western-blotting and MDA by spectrofluorimetry. After the incubation of the aortic rings in TMAO solutions for 1 h, there was no difference in vasoconstrictor and non-endothelial vasodilator response between the studied doses. TMAO acutely induced oxidative stress and inflammation, significantly increasing levels of MDA and the expression of NF-κB, NRF2, SOD1, and iNOS, mostly in a dose-dependent manner. Our study showed the lack of a short-term effect of studied TMAO doses on vascular contractility, but demonstrated an acute prooxidative effect and activation of major inflammatory pathways, which can partially explain the detrimental effects of TMAO in cardiovascular disease.
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Affiliation(s)
- Cristian Marius Florea
- Department of Physiology, Iuliu Hatieganu University of Medicine and Pharmacy, Clinicilor Street, No 1, Cluj-Napoca, Romania
| | - Ioana Baldea
- Department of Physiology, Iuliu Hatieganu University of Medicine and Pharmacy, Clinicilor Street, No 1, Cluj-Napoca, Romania.
| | - Radu Rosu
- Fifth Department of Internal Medicine, Cardiology Clinic, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Remus Moldovan
- Department of Physiology, Iuliu Hatieganu University of Medicine and Pharmacy, Clinicilor Street, No 1, Cluj-Napoca, Romania
| | - Nicoleta Decea
- Department of Physiology, Iuliu Hatieganu University of Medicine and Pharmacy, Clinicilor Street, No 1, Cluj-Napoca, Romania
| | - Gabriela Adriana Filip
- Department of Physiology, Iuliu Hatieganu University of Medicine and Pharmacy, Clinicilor Street, No 1, Cluj-Napoca, Romania
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Shanmugham M, Bellanger S, Leo CH. Gut-Derived Metabolite, Trimethylamine-N-oxide (TMAO) in Cardio-Metabolic Diseases: Detection, Mechanism, and Potential Therapeutics. Pharmaceuticals (Basel) 2023; 16:ph16040504. [PMID: 37111261 PMCID: PMC10142468 DOI: 10.3390/ph16040504] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/17/2023] [Accepted: 03/23/2023] [Indexed: 03/30/2023] Open
Abstract
Trimethylamine N-oxide (TMAO) is a biologically active gut microbiome-derived dietary metabolite. Recent studies have shown that high circulating plasma TMAO levels are closely associated with diseases such as atherosclerosis and hypertension, and metabolic disorders such as diabetes and hyperlipidemia, contributing to endothelial dysfunction. There is a growing interest to understand the mechanisms underlying TMAO-induced endothelial dysfunction in cardio-metabolic diseases. Endothelial dysfunction mediated by TMAO is mainly driven by inflammation and oxidative stress, which includes: (1) activation of foam cells; (2) upregulation of cytokines and adhesion molecules; (3) increased production of reactive oxygen species (ROS); (4) platelet hyperreactivity; and (5) reduced vascular tone. In this review, we summarize the potential roles of TMAO in inducing endothelial dysfunction and the mechanisms leading to the pathogenesis and progression of associated disease conditions. We also discuss the potential therapeutic strategies for the treatment of TMAO-induced endothelial dysfunction in cardio-metabolic diseases.
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Affiliation(s)
- Meyammai Shanmugham
- Science, Math & Technology, Singapore University of Technology & Design, 8 Somapah Road, Singapore 487372, Singapore
| | - Sophie Bellanger
- A*STAR Skin Research Labs, Agency for Science, Technology and Research, Singapore 138648, Singapore
| | - Chen Huei Leo
- Science, Math & Technology, Singapore University of Technology & Design, 8 Somapah Road, Singapore 487372, Singapore
- Correspondence: ; Tel.: +65-6434-8213
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Effects of acute administration of trimethylamine N-oxide on endothelial function: a translational study. Sci Rep 2022; 12:8664. [PMID: 35606406 PMCID: PMC9127094 DOI: 10.1038/s41598-022-12720-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/13/2022] [Indexed: 01/07/2023] Open
Abstract
Elevated circulating levels of nutrient-derived trimethylamine N-oxide (TMAO) have been associated with the onset and progression of cardiovascular disease by promoting athero-thrombosis. However, in conditions like bariatric surgery (Roux-en-Y gastric bypass, RYGB), stable increases of plasma TMAO are associated with improved endothelial function and reduced cardiovascular morbidity and mortality, thus questioning whether a mechanistic relationship between TMAO and endothelial dysfunction exists. Herein, we translationally assessed the effects of acute TMAO exposure on endothelial dysfunction, thrombosis and stroke. After RYGB, fasting circulating levels of TMAO increased in patients and obese rats, in parallel with an improved gluco-lipid profile and higher circulating bile acids. The latter enhanced FXR-dependent signalling in rat livers, which may lead to higher TMAO synthesis post RYGB. In lean rats, acute TMAO injection (7 mg kg-1) 1.5-h before sacrifice and ex-vivo 30-min incubation of thoracic aortas with 10-6 M TMAO did not impair vasodilation in response to acetylcholine (Ach), glucagon-like peptide 1, or insulin. Similarly, in lean WT mice (n = 5-6), TMAO injection prior to subjecting mice to ischemic stroke or arterial thrombosis did not increase its severity compared to vehicle treated mice. Endothelial nitric oxide synthase (eNOS) activity and intracellular stress-activated pathways remained unaltered in aorta of TMAO-injected rats, as assessed by Western Blot. Pre-incubation of human aortic endothelial cells with TMAO (10-6 M) did not alter NO release in response to Ach. Our results indicate that increased plasmatic TMAO in the near-physiological range seems to be a neutral bystander to vascular function as translationally seen in patients after bariatric surgery or in healthy lean rodent models and in endothelial cells exposed acutely to TMAO.
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El Chamieh C, Liabeuf S, Massy Z. Uremic Toxins and Cardiovascular Risk in Chronic Kidney Disease: What Have We Learned Recently beyond the Past Findings? Toxins (Basel) 2022; 14:toxins14040280. [PMID: 35448889 PMCID: PMC9028122 DOI: 10.3390/toxins14040280] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 04/10/2022] [Accepted: 04/11/2022] [Indexed: 12/13/2022] Open
Abstract
Patients with chronic kidney disease (CKD) have an elevated prevalence of atheromatous (ATH) and/or non-atheromatous (non-ATH) cardiovascular disease (CVD) due to an array of CKD-related risk factors, such as uremic toxins (UTs). Indeed, UTs have a major role in the emergence of a spectrum of CVDs, which constitute the leading cause of death in patients with end-stage renal disease. The European Uremic Toxin Work Group has identified over 100 UTs, more than 25 of which are dietary or gut-derived. Even though relationships between UTs and CVDs have been described in the literature, there are few reviews on the involvement of the most toxic compounds and the corresponding physiopathologic mechanisms. Here, we review the scientific literature on the dietary and gut-derived UTs with the greatest toxicity in vitro and in vivo. A better understanding of these toxins’ roles in the elevated prevalence of CVDs among CKD patients might facilitate the development of targeted treatments. Hence, we review (i) ATH and non-ATH CVDs and the respective levels of risk in patients with CKD and (ii) the mechanisms that underlie the influence of dietary and gut-derived UTs on CVDs.
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Affiliation(s)
- Carolla El Chamieh
- Center for Research in Epidemiology and Population Health (CESP), Paris-Saclay University, Versailles-Saint-Quentin-en-Yvelines University (UVSQ), INSERM UMRS 1018, F-94807 Villejuif, France;
| | - Sophie Liabeuf
- Pharmacology Department, Amiens University Hospital, F-80000 Amiens, France
- MP3CV Laboratory, EA7517, Jules Verne University of Picardie, F-80000 Amiens, France
- Correspondence: (S.L.); (Z.M.)
| | - Ziad Massy
- Nephrology Department, Ambroise Paré University Hospital, APHP, F-92100 Paris, France
- Correspondence: (S.L.); (Z.M.)
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Maiuolo J, Carresi C, Gliozzi M, Mollace R, Scarano F, Scicchitano M, Macrì R, Nucera S, Bosco F, Oppedisano F, Ruga S, Coppoletta AR, Guarnieri L, Cardamone A, Bava I, Musolino V, Paone S, Palma E, Mollace V. The Contribution of Gut Microbiota and Endothelial Dysfunction in the Development of Arterial Hypertension in Animal Models and in Humans. Int J Mol Sci 2022; 23:ijms23073698. [PMID: 35409057 PMCID: PMC8999124 DOI: 10.3390/ijms23073698] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 02/06/2023] Open
Abstract
The maintenance of the physiological values of blood pressure is closely related to unchangeable factors (genetic predisposition or pathological alterations) but also to modifiable factors (dietary fat and salt, sedentary lifestyle, overweight, inappropriate combinations of drugs, alcohol abuse, smoking and use of psychogenic substances). Hypertension is usually characterized by the presence of a chronic increase in systemic blood pressure above the threshold value and is an important risk factor for cardiovascular disease, including myocardial infarction, stroke, micro- and macro-vascular diseases. Hypertension is closely related to functional changes in the endothelium, such as an altered production of vasoconstrictive and vasodilator substances, which lead to an increase in vascular resistance. These alterations make the endothelial tissue unresponsive to autocrine and paracrine stimuli, initially determining an adaptive response, which over time lead to an increase in risk or disease. The gut microbiota is composed of a highly diverse bacterial population of approximately 1014 bacteria. A balanced intestinal microbiota preserves the digestive and absorbent functions of the intestine, protecting from pathogens and toxic metabolites in the circulation and reducing the onset of various diseases. The gut microbiota has been shown to produce unique metabolites potentially important in the generation of hypertension and endothelial dysfunction. This review highlights the close connection between hypertension, endothelial dysfunction and gut microbiota.
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Affiliation(s)
- Jessica Maiuolo
- Laboratory of Pharmaceutical Biology, in IRC-FSH Center, Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy;
- Correspondence: (J.M.); (M.G.)
| | - Cristina Carresi
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
| | - Micaela Gliozzi
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Correspondence: (J.M.); (M.G.)
| | - Rocco Mollace
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Federica Scarano
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Miriam Scicchitano
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Roberta Macrì
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Saverio Nucera
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Francesca Bosco
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Francesca Oppedisano
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Stefano Ruga
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
| | - Anna Rita Coppoletta
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
| | - Lorenza Guarnieri
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
| | - Antonio Cardamone
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
| | - Irene Bava
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Vincenzo Musolino
- Laboratory of Pharmaceutical Biology, in IRC-FSH Center, Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy;
| | - Sara Paone
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Ernesto Palma
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- Nutramed S.c.a.r.l, Complesso Ninì Barbieri, Roccelletta di Borgia, 88021 Catanzaro, Italy;
| | - Vincenzo Mollace
- IRC-FSH Department of Health Sciences, University “Magna Græcia” of Catanzaro Italy, 88021 Catanzaro, Italy; (C.C.); (R.M.); (F.S.); (M.S.); (R.M.); (S.N.); (F.B.); (F.O.); (S.R.); (A.R.C.); (L.G.); (A.C.); (I.B.); (E.P.); (V.M.)
- IRCCS San Raffaele, Via di Valcannuta 247, 00133 Rome, Italy
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Matsumoto T, Taguchi N, Yoshioka M, Osada T, Taguchi K, Kobayashi T. [Relationship between gut microbiota-derived substances and vascular function: focus on indoxyl sulfate and trimethylamine-N-oxide]. Nihon Yakurigaku Zasshi 2022; 157:316-320. [PMID: 36047143 DOI: 10.1254/fpj.22029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Emerging evidences suggest that gut microbiota-derived substances play a pivotal role in the regulation of host homeostasis including vascular function. Actually, these substances and/or their metabolites can be presented in circulation and local tissue and their levels are often abnormal in the pathophysiological states. Therefore, to determine the role of them in physiological function is important in human health. On the other hand, vascular dysfunction is a key event in the initiation and progression of systematic complications of cardiovascular, kidney and metabolic diseases including hypertension, dyslipidemia, diabetes, and atherosclerosis. Although abnormalities in endothelial and vascular smooth muscle cells play an important role on vascular dysfunction, emerging evidences has suggested that gut microbiota-derived substances can directly or indirectly affect these cellular functions. The present review will focus on the relationship between vascular function and indoxyl sulfate or trimethylamine-N-oxide (TMAO).
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Natsume Taguchi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Madoka Yoshioka
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Tomoe Osada
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Kumiko Taguchi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Tsuneo Kobayashi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
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Yang Y, Yang B, Li X, Xue L, Liu B, Liang Y, Zhao Z, Luo Q, Liu Z, Zeng Q, Xiong C. Higher circulating Trimethylamine N-oxide levels are associated with worse severity and prognosis in pulmonary hypertension: a cohort study. Respir Res 2022; 23:344. [PMID: 36517838 PMCID: PMC9749156 DOI: 10.1186/s12931-022-02282-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 12/07/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Trimethylamine N-oxide (TMAO), the gut microbiota-dependent metabolite, is a potential biomarker in several cardiovascular diseases. However, no study has investigated its value in pulmonary hypertension (PH). Therefore, this study aimed to explore the association between plasma TMAO levels and prognosis in patients with PH. METHODS Inpatients with idiopathic/heritable pulmonary arterial hypertension (IPAH/HPAH), PAH associated with congenital heart disease (CHD-PAH), and chronic thromboembolic pulmonary hypertension (CTEPH) at Fuwai Hospital were enrolled after excluding those with relative comorbidities. The endpoint was defined as a composite outcome including death, rehospitalisation due to heart failure, and at least 15% decreased 6-min walk distance from the baseline. Fasting blood samples were collected to measure plasma levels of TMAO and other clinical indicators. The associations between TMAO levels with disease severity and patients' prognosis were investigated. RESULTS In total, 163 patients with PH were included, with a mean follow-up duration of 1.3 years. After adjusting for confounding factors, elevated TMAO levels were still associated with severe disease conditions. TMAO levels dynamically decreased in stable and improved patients after treatment [ΔTMAO = - 0.2 (- 1.6, 0.7) μmol/L, P = 0.006]. Moreover, high plasma TMAO levels predicted a poor prognosis in the PH cohort (P < 0.001), and the association remained significant after adjusting the confounders, including treatment, risk stratification, and PH subtypes. CONCLUSION Elevated plasma TMAO levels were associated with severe disease conditions and poor prognosis in patients with PH, indicating its potential biomarker role in PH.
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Affiliation(s)
- Yicheng Yang
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Beilan Yang
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Xin Li
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Lin Xue
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Bingyang Liu
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Yanru Liang
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Zhihui Zhao
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Qin Luo
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Zhihong Liu
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Qixian Zeng
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
| | - Changming Xiong
- grid.506261.60000 0001 0706 7839Center of Respiratory and Pulmonary Vascular Disease, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 North Lishi Road, Xicheng District, Beijing, 100037 China
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9
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Matsumoto T, Takayanagi K, Katome T, Kojima M, Taguchi K, Kobayashi T. Reduced Relaxant Response to Adenine in the Superior Mesenteric Artery of Spontaneously Hypertensive Rats. Biol Pharm Bull 2021; 44:1530-1535. [PMID: 34602562 DOI: 10.1248/bpb.b21-00437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the vascular response to nucleobase adenine using freshly isolated superior mesenteric arteries of spontaneously hypertensive rats (SHR) and its control, Wistar Kyoto (WKY) rats. Endothelium-dependent and endothelium-independent relaxations were assessed in isolated segments in an organ bath. The releases of the metabolites of thromboxane A2 and prostaglandin I2 were also detected. Adenine induced vasorelaxation in both the endothelium-intact and endothelium-denuded arteries in a concentration-dependent manner. In the SHR group, the adenine-induced relaxation was slightly but significantly reduced in the endothelium-intact rings when compared with that in the WKY group. However, the relaxation in the endothelium-denuded rings were similar between the two groups. The difference in the adenine-mediated relaxation in the superior mesenteric arteries between the SHR and WKY groups was eliminated by endothelial denudation and a nitric oxide (NO) synthase inhibitor. In the absence and presence of adenine, SHR tended to have higher levels of metabolites of thromboxane A2 and prostaglandin I2 compared with WKY. However, adenine did not induce the release of these substances in the arteries in both the SHR and WKY groups. These results suggest that the reduced adenine-mediated relaxation in the superior mesenteric arteries in SHR is due to a lack of contribution from the endothelium-derived NO and not from the release of prostanoids.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Keisuke Takayanagi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Tomoki Katome
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Mihoka Kojima
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Kumiko Taguchi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Tsuneo Kobayashi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
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10
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Hamad A, Ozkan MH, Uma S. Trimethylamine-N-oxide (TMAO) Selectively Disrupts Endothelium-Dependent Hyperpolarization-Type Relaxations in a Time-Dependent Manner in Rat Superior Mesenteric Artery. Biol Pharm Bull 2021; 44:1220-1229. [PMID: 34471050 DOI: 10.1248/bpb.b20-00767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The vascular action of trimethylamine-N-oxide (TMAO)-the gut microbiota-derived metabolite-in contributing cardiovascular disease is a controversial topic. A recent study has shown that acute exposure of TMAO at moderate concentrations inhibits endothelium-dependent hyperpolarization (EDH)-type relaxations selectively in rat isolated femoral arteries, but not in mesenteric arteries. Here we determined the efficacy of higher TMAO concentrations with longer exposure times on vascular reactivity in rat isolated superior mesenteric arteries. Acetylcholine-induced EDH-type relaxations were examined before and after incubation with TMAO (0.1-10 mM) at increasing exposure times (1-24 h). One- and 4-h-incubations with TMAO at 0.1-3 mM did not cause any change in EDH-type relaxations. However, when the incubation time was increased to 24 h, responses to acetylcholine were reduced in arteries incubated with 1-3 mM TMAO. In addition, at higher TMAO concentration (10 mM) the decrease in EDH relaxations could be detected both in 4-h- and 24-h-incubations. The EDH-relaxations were preserved in rings incubated with 10 mM TMAO for 24 h in the presence of SKA-31 (10 µM), the small (SKCa)- and intermediate (IKCa)-conductance calcium-activated potassium channel activator. Contractile responses to phenylephrine increased in arteries exposed to 10 mM TMAO for 24 h. Interestingly, nitric oxide (NO)-mediated relaxations remained unchanged in arteries treated for 24 h at any TMAO concentration. Our study revealed that TMAO selectively disrupted EDH-type relaxations time-dependently without interfering with NO-induced vasodilation in rat isolated mesenteric arteries. Disruption of these relaxations may help explain the causal role of elevated TMAO levels in certain vascular diseases.
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Affiliation(s)
- Abdelrahman Hamad
- Department of Pharmacology, Faculty of Pharmacy, Hacettepe University
| | | | - Serdar Uma
- Department of Pharmacology, Faculty of Pharmacy, Hacettepe University
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11
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Matsumoto T, Takayanagi K, Katome T, Kojima M, Taguchi K, Kobayashi T. Extracellular Uridine Nucleotides-Induced Contractions Were Increased in Femoral Arteries of Spontaneously Hypertensive Rats. Pharmacology 2021; 106:435-445. [PMID: 34139711 DOI: 10.1159/000516893] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/27/2021] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Femoral arterial dysfunction including abnormal vascular responsiveness to endogenous ligands was often seen in arterial hypertension. Extracellular nucleotides including uridine 5'-diphosphate (UDP) and uridine 5'-triphosphate (UTP) play important roles for homeostasis in the vascular system including controlling the vascular tone. However, responsiveness to UDP and UTP in femoral arteries under arterial hypertension remains unclear. The aim of this study was to investigate if hypertension has an effect of vasoconstrictive responsiveness to UDP and UTP in femoral arteries of spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats (WKYs) after 7 and 12 months old. METHODS Organ baths were conducted to determine vascular reactivity in isolated femoral arterial rings. RESULTS In femoral arteries obtained from 12-month-old rats, augmented contractile responses to UDP and UTP were seen in femoral arteries of SHR than in those of WKY under situations not only intact but also nitric oxide synthase inhibition, whereas no difference of extracellular potassium-induced vasocontraction was seen in both SHR and WKY groups. Similar contraction trends occurred in femoral arteries obtained from 7-month-old rats. Moreover, contractions induced by UDP and UTP were increased in endothelium-denuded arteries. Cyclooxygenase inhibition decreased the contractions induced by these nucleotides and abolished the differences in responses between the SHR and WKY groups. CONCLUSIONS This study demonstrates the importance of regulation of extracellular uridine nucleotides-induced contractions in hypertension-associated peripheral arterial diseases.
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Affiliation(s)
- Takayuki Matsumoto
- Institute of Medicinal Chemistry, Department of Physiology and Morphology, Hoshi University, Tokyo, Japan
| | - Keisuke Takayanagi
- Institute of Medicinal Chemistry, Department of Physiology and Morphology, Hoshi University, Tokyo, Japan
| | - Tomoki Katome
- Institute of Medicinal Chemistry, Department of Physiology and Morphology, Hoshi University, Tokyo, Japan
| | - Mihoka Kojima
- Institute of Medicinal Chemistry, Department of Physiology and Morphology, Hoshi University, Tokyo, Japan
| | - Kumiko Taguchi
- Institute of Medicinal Chemistry, Department of Physiology and Morphology, Hoshi University, Tokyo, Japan
| | - Tsuneo Kobayashi
- Institute of Medicinal Chemistry, Department of Physiology and Morphology, Hoshi University, Tokyo, Japan
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12
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Targeting Uremic Toxins to Prevent Peripheral Vascular Complications in Chronic Kidney Disease. Toxins (Basel) 2020; 12:toxins12120808. [PMID: 33419312 PMCID: PMC7765928 DOI: 10.3390/toxins12120808] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 12/24/2022] Open
Abstract
Chronic kidney disease (CKD) exhibits progressive kidney dysfunction and leads to disturbed homeostasis, including accumulation of uremic toxins, activated renin-angiotensin system, and increased oxidative stress and proinflammatory cytokines. Patients with CKD are prone to developing the peripheral vascular disease (PVD), leading to poorer outcomes than those without CKD. Cumulative evidence has showed that the synergy of uremic milieu and PVD could exaggerate vascular complications such as limb ischemia, amputation, stenosis, or thrombosis of a dialysis vascular access, and increase mortality risk. The role of uremic toxins in the pathogenesis of vascular dysfunction in CKD has been investigated. Moreover, growing evidence has shown the promising role of uremic toxins as a therapeutic target for PVD in CKD. This review focused on uremic toxins in the pathophysiology, in vitro and animal models, and current novel clinical approaches in reducing the uremic toxin to prevent peripheral vascular complications in CKD patients.
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13
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Matsumoto T, Takayanagi K, Kojima M, Taguchi K, Kobayashi T. Differential Contractile Reactivity to Nucleotides in Femoral Arteries of OLETF and LETO Rats. Biol Pharm Bull 2020; 43:1987-1992. [PMID: 33268721 DOI: 10.1248/bpb.b20-00653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extracellular nucleotides play an important role in the regulation of vascular function, and an abnormal vascular function is an important participant in the development and progression of diabetic vascular complications. The purpose of this study was to determine whether contractile responses induced by extracellular nucleotides and a dinucleotide, uridine adenosine tetraphosphate (Up4A), in femoral arteries would be altered at the chronic stage of type 2 diabetes. We determined the changes in contractile reactivity induced by ATP, uridine triphosphate (UTP), uridine diphosphate (UDP), and Up4A in the femoral arteries of Otsuka Long-Evans Tokushima Fatty (OLETF) rats (aged male type 2 diabetic rats) and, Long-Evans Tokushima Otsuka (LETO) rats (controls for OLETF rats). ATP-induced contractions were greater in OLETF rats than in LETO rats. UTP-induced contractions were lower in OLETF rats than in LETO rats. UDP- and Up4A-induced contractions were similar between OLETF and LETO rats. The femoral artery contractile changes induced by the extracellular nucleotides and dinucleotide were similar when nitric oxide synthase was inhibited. These results suggest that the extent of femoral artery contractile reactivity to nucleotides/dinucleotides differs during long-term duration of type 2 diabetes.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Keisuke Takayanagi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Mihoka Kojima
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Kumiko Taguchi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
| | - Tsuneo Kobayashi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University
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14
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Indoxyl sulfate induces ROS production via the aryl hydrocarbon receptor-NADPH oxidase pathway and inactivates NO in vascular tissues. Life Sci 2020; 265:118807. [PMID: 33232689 DOI: 10.1016/j.lfs.2020.118807] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/10/2020] [Accepted: 11/19/2020] [Indexed: 12/23/2022]
Abstract
AIMS The uremic toxin indoxyl sulfate (IS) was reported to be the cause of cardiovascular disease associated with chronic kidney disease. Therefore, we evaluated the direct influences of IS on vascular function, focusing on the superoxide anion (O2-) and nitric oxide (NO)/soluble guanylate cyclase (sGC) pathways. MAIN METHODS Isolated rat thoracic aortas with and without vascular endothelium were incubated with IS for 4 h in a physiological solution. In some experiments, several inhibitors were treated 30 min before the addition of IS. O2- production was measured by the chemiluminescence method, and the vascular reactivity to different vasorelaxants was examined using organ chamber technique. KEY FINDINGS 1) Experiments using endothelium-intact vascular rings: IS significantly increased O2- production. The increase was suppressed by addition of the NADPH oxidase inhibitor apocynin, the antioxidant ascorbic acid and the aryl hydrocarbon receptor (AhR) inhibitor CH223191. Furthermore, IS attenuated the acetylcholine (ACh)-induced vasorelaxantion, which was suppressed by addition of the above drugs. 2) Experiments using endothelium-denuded vascular rings: IS significantly increased O2- production and also attenuated sodium nitroprusside (SNP)-induced vasorelaxation. These influences of IS were normalized only by ascorbic acid addition. On the other hand, IS did not affect the vasorelaxation by the sGC stimulator BAY 41-2272. SIGNIFICANCE This study suggested that IS causes O2- production in vascular tissues, thereby attenuating ACh- and SNP-induced vasorelaxation, probably through NO inactivation. Furthermore, it is reasonable to consider that IS-promoted O2- production in the presence of vascular endothelium is through binding to AhR and the activation of NADPH oxidase.
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15
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Matsumoto T, Kojima M, Takayanagi K, Taguchi K, Kobayashi T. Role of S-Equol, Indoxyl Sulfate, and Trimethylamine N-Oxide on Vascular Function. Am J Hypertens 2020; 33:793-803. [PMID: 32300778 PMCID: PMC7481967 DOI: 10.1093/ajh/hpaa053] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/21/2020] [Accepted: 03/20/2020] [Indexed: 12/15/2022] Open
Abstract
Gut microbiota have been emerging as important contributors to the regulation of host homeostasis. Accordingly, several substances converted by gut microbiota can have beneficial or adverse effects on human health. Among them, S-equol, which is produced from the isoflavone daidzein in the human and animal gut by certain microbiota, exerts estrogenic and antioxidant activities. Indoxyl sulfate, which is metabolized in the liver from indole converted from dietary tryptophan by bacterial tryptophanases in the colon, is known as a protein-bound uremic toxin. Trimethylamine N-oxide, which is generated via the oxidization of gut microbiota-derived trimethylamine by hepatic flavin monooxygenases, is known as an accelerator of atherosclerosis. The aforementioned gut-derived substances could be potential regulators of systematic tissue/organ function, including the vascular system. Macro- and microvascular complications of cardiovascular and metabolic diseases, including atherosclerosis, hypertension, and diabetes, occur systemically and represent the principal cause of morbidity and mortality. Vascular endothelial and smooth muscle dysfunction play pivotal roles in the development and progression of vasculopathies. We herein review the link between the aforementioned gut-derived substances and endothelial and vascular smooth muscle cell function. This information will provide a conceptual framework that would allow the development of novel preventive and/or therapeutic approaches against vasculopathies.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
| | - Mihoka Kojima
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
| | - Keisuke Takayanagi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
| | - Kumiko Taguchi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
| | - Tsuneo Kobayashi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
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16
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Abstract
We critically review potential involvement of trimethylamine N-oxide (TMAO) as a link between diet, the gut microbiota and CVD. Generated primarily from dietary choline and carnitine by gut bacteria and hepatic flavin-containing mono-oxygenase (FMO) activity, TMAO could promote cardiometabolic disease when chronically elevated. However, control of circulating TMAO is poorly understood, and diet, age, body mass, sex hormones, renal clearance, FMO3 expression and genetic background may explain as little as 25 % of TMAO variance. The basis of elevations with obesity, diabetes, atherosclerosis or CHD is similarly ill-defined, although gut microbiota profiles/remodelling appear critical. Elevated TMAO could promote CVD via inflammation, oxidative stress, scavenger receptor up-regulation, reverse cholesterol transport (RCT) inhibition, and cardiovascular dysfunction. However, concentrations influencing inflammation, scavenger receptors and RCT (≥100 µm) are only achieved in advanced heart failure or chronic kidney disease (CKD), and greatly exceed pathogenicity of <1-5 µm levels implied in some TMAO-CVD associations. There is also evidence that CVD risk is insensitive to TMAO variance beyond these levels in omnivores and vegetarians, and that major TMAO sources are cardioprotective. Assessing available evidence suggests that modest elevations in TMAO (≤10 µm) are a non-pathogenic consequence of diverse risk factors (ageing, obesity, dyslipidaemia, insulin resistance/diabetes, renal dysfunction), indirectly reflecting CVD risk without participating mechanistically. Nonetheless, TMAO may surpass a pathogenic threshold as a consequence of CVD/CKD, secondarily promoting disease progression. TMAO might thus reflect early CVD risk while providing a prognostic biomarker or secondary target in established disease, although mechanistic contributions to CVD await confirmation.
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