Key pointsr Age-related arterial dysfunction, characterized by oxidative stress-and inflammation-mediated endothelial dysfunction and arterial stiffening, is the primary risk factor for cardiovascular diseases.Vienna E. Brunt received her PhD in Human Physiology from the University of Oregon in 2016. She is currently a postdoctoral fellow in Dr D. R. Seals' Integrative Physiology of Aging Laboratory at the University of Colorado Boulder. The studies described in the present study represent work carried out as part of an NIH T32 fellowship through the Division of Cardiology at the University of Colorado Denver. Her long-term research goals are to investigate the efficacy of novel interventions for preserving vascular function with ageing, thereby preventing and/or delaying the progression of cardiovascular diseases. Rachel A. Gioscia-Ryan completed her PhD in the Integrative Physiology of Aging Laboratory at the University of Colorado Boulder in 2016 and is currently in medical school at the University of Michigan. She is pursuing a career as a clinician-scientist conducting integrative physiological studies with the aim of improving human health and patient care. * These authors contributed equally to this work.Abstract Oxidative stress-mediated arterial dysfunction (e.g. endothelial dysfunction and large elastic artery stiffening) is the primary mechanism driving age-related cardiovascular diseases. Accumulating evidence suggests the gut microbiome modulates host physiology because dysregulation ('gut dysbiosis') has systemic consequences, including promotion of oxidative stress. The present study aimed to determine whether the gut microbiome modulates arterial function with ageing. We measured arterial function in young and older mice after 3-4 weeks of treatment with broad-spectrum, poorly-absorbed antibiotics to suppress the gut microbiome. To identify potential mechanistic links between the gut microbiome and age-related arterial dysfunction, we sequenced microbiota from young and older mice and measured plasma levels of the adverse gut-derived metabolite trimethylamine N-oxide (TMAO). In old mice, antibiotics reversed endothelial dysfunction [area-under-the-curve carotid artery dilatation to acetylcholine in young: 345 ± 16 AU vs. old control (OC): 220 ± 34 AU, P < 0.01; vs. old antibiotic-treated (OA): 334 ± 15 AU; P < 0.01 vs. OC] and arterial stiffening (aortic pulse wave velocity in young: 3.62 ± 0.15 m s −1 vs. OC: 4.43 ± 0.38 m s −1 ; vs. OA: 3.52 ± 0.35 m s −1 ; P = 0.03). These improvements were accompanied by lower oxidative stress and greater antioxidant enzyme expression. Ageing altered the abundance of gut microbial taxa associated with gut dysbiosis. Lastly, plasma TMAO was higher with ageing (young: 2.6 ± 0.4 μmol L −1 vs. OC: 7.2 ± 2.0 μmol L −1 ; P < 0.0001) and suppressed by antibiotic treatment (OA: 1.2 ± 0.2 μmol L −1 ; P < 0.0001 vs. OC). The results of the present study provide the first evidence for the gut microbiome being an important mediator of age-related arterial dysfunction and ...

Objective: The objective of this study was to test the hypothesis that the multi-strain probiotic VSL#3 would attenuate the increase in fasting plasma concentrations of trimethylamine-N-oxide (TMAO) following a high-fat diet. Methods: Nineteen healthy, non-obese males (18-30 years) participated in the present study. Following a 2-week eucaloric control diet, subjects were randomized to either VSL#3 (900 billion live bacteria) or placebo (cornstarch) during the consumption of a hypercaloric (11,000 kcal day 21 ), high-fat diet (55% fat) for 4 weeks. Plasma TMAO, L-carnitine, choline, and betaine (UPLC-MS/MS) were measured at baseline and following a high-fat diet. Results: Plasma TMAO significantly increased 89% 6 66% vs. 115% 6 61% in both the VSL#3 and placebo groups, respectively; however, the magnitude of change in plasma TMAO was not different (P > 0.05) between them. Plasma L-carnitine, choline, and betaine concentrations did not increase following the high-fat diet in either group. Conclusions: A high-fat diet increases plasma TMAO in healthy, normal-weight, young males. However, VSL#3 treatment does not appear to influence plasma TMAO concentrations following a high-fat diet. Future studies are needed to determine whether other therapeutic strategies can attenuate the production of TMAO.

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