Connections between serum Trimethylamine N-Oxide (TMAO), a gut-derived metabolite, and vascular biomarkers evaluating arterial stiffness and subclinical atherosclerosis in children with obesity

Maternal consumption of urbanized diet compromises early-life health in association with gut microbiota

Urbanization has significantly transformed dietary habits worldwide, contributing to a globally increased burden of non-communicable diseases and altered gut microbiota landscape. However, it is often overlooked that the adverse effects of these dietary changes can be transmitted from the mother to offspring during early developmental stages, subsequently influencing the predisposition to various diseases later in life. This review aims to delineate the detrimental effects of maternal urban-lifestyle diet (urbanized diet) on early-life health and gut microbiota assembly, provide mechanistic insights on how urbanized diet mediates mother-to-offspring transfer of bioactive substances in both intrauterine and extrauterine and thus affects fetal and neonatal development. Moreover, we also further propose a framework for developing microbiome-targeted precision nutrition and diet strategies specifically for pregnant and lactating women. The establishment of such knowledge can help develop proactive preventive measures from the beginning of life, ultimately reducing the long-term risk of disease and improving public health outcomes.

Carotid artery intima-media thickness values in obese or overweight children: a meta-analysis

OBJECTIVE

Carotid artery intima-media thickness (IMT) is a non-invasive ultrasound marker of early atherosclerosis. This systematic review and meta-analysis aim to report the published differences in IMT values in children living with overweight or obesity compared to controls with normal weight.

METHODS

This review was conducted according to PRISMA guidelines, including only cohorts with normal controls. Inclusion criteria were IMT measured using B-mode or radiofrequency (RF) techniques and based on the four consensuses: American Heart Association, Association for European Pediatric Cardiology, Mannheim Consensus, and American Society of Echocardiography. We used the body mass index based on the World Health Organization growth standard definitions of obesity in children. Relevant articles were extracted from PubMed, Cochrane Library, Embase, and Web of Science searched from inception to February 2024. A meta-analysis was done by a biostatistician using the R-software version 4.0.2.

RESULTS

We obtained 15 B-mode-based and two RF echo-tracking-based IMT measurement studies. IMT is significantly increased in children living with obesity. The mean IMT was 0.041 mm, 95% confidence interval (CI): 0.052; 0.031 higher in children with overweight/obesity, using the B-mode technique, and 0.045 mm, 95% CI: 0.062; 0.029 higher in children with overweight/obesity using RF technique.

CONCLUSION

This meta-analysis shows that IMT is significantly increased in children with obesity compared to normal-weight children according to both techniques.

KEY POINTS

Question IMT measured according to known consensuses is significantly increased in children living with obesity. Findings Mean IMT was 0.041 mm higher in children living with obesity using the B-mode technique and 0.045 mm using the RF technique. Clinical relevance There are different techniques to measure IMT in children. This meta-analysis, using cohorts of children living with obesity compared to normal weight controls, shows a significantly increased IMT in children living with obesity.

Gut Microbiota Metabolite TMAO and Adolescent Cardiometabolic Health: A Cross-sectional Analysis

Background

Trimethylamine N-oxide (TMAO) is a metabolite derived from gut microbiota that has been associated with cardiovascular and metabolic disease risk in adults. However, its role in assessing cardiometabolic risk in adolescents is unclear.

Objective

This study investigates the association between serum TMAO levels and cardiometabolic health indicators in Brazilian adolescents.

Materials and Methods

This is a multicenter, cross-sectional analysis involving 4446 participants aged 12 to 17 years from four Brazilian cities. Serum TMAO levels were quantified using liquid chromatography-tandem mass spectrometry, and associations with clinical, metabolic, and inflammatory variables were evaluated through multivariate linear regression analyses.

Results

After adjusting for potential confounders, being in the highest tertile of serum TMAO was positively associated with waist circumference [β 1.45; 95% confidence interval (CI) 0.77, 2.14; P < .001], body mass index Z-score (β .19; 95% CI 0.10, 0.27; P < .001), and C-reactive protein (β .24; 95% CI 0.13, 0.34; P < .001). A negative association between the highest tertile of TMAO and fasting plasma glucose was also observed (β -1.22; 95% CI -1.77, -0.66; P < .001).

Conclusion

TMAO may serve as an emerging biomarker for cardiometabolic risk assessment in adolescents.

Causal effects of metabolites on malignant neoplasm of bone and articular cartilage: a mendelian randomization study

Objective

Previous research has demonstrated that metabolites play a significant role in modulating disease phenotypes; nevertheless, the causal association between metabolites and malignant malignancies of bones and joint cartilage (MNBAC)has not been fully elucidated.

Methods

This study used two-sample Mendelian randomization (MR) to explore the causal correlation between 1,400 metabolites and MNBAC. Data from recent genome-wide association studies (GWAS) involving 8,299 individuals were summarized. The GWAS summary data for metabolites were acquired from the IEU Open GWAS database, while those for MNBAC were contributed by the Finnish Consortium. We employed eight distinct MR methodologies: simple mode, maximum likelihood estimator, MR robust adjusted profile score, MR-Egger, weighted mode, weighted median, MR-PRESSO and inverse variance weighted to scrutinize the causal association between metabolites engendered by each gene and MNBAC. Consequently, we evaluated outliers, horizontal pleiotropy, heterogeneity, the impact of single nucleotide polymorphisms (SNPs), and adherence to the normal distribution assumption in the MR analysis.

Results

Our findings suggested a plausible causative relationship between N-Formylmethionine (FMet) levels, lignoceroylcarnitine (C24) levels, and MNBAC. We observed a nearly significant causal association between FMet levels and MNBAC within the cohort of 1,400 metabolites (P = 0.024, odds ratio (OR) = 3.22; 95% CI [1.16-8.92]). Moreover, we ascertained a significant causal link between levels of C24 and MNBAC (P = 0.0009; OR = 0.420; 95%CI [0.25-0.70]). These results indicate a potential causative relationship between FMet, C24 level and MNBAC.

Conclusion

The occurrence of MNBAC may be causally related to metabolites. This might unveil new possibilities for investigating early detection and treatment of MNBAC.

Independent Predictors of Circulating Trimethylamine N-Oxide (TMAO) and Resistin Levels in Subjects with Obesity: Associations with Carotid Intima-Media Thickness and Metabolic Parameters

Background: Obesity contributes to cardiometabolic risk, including subclinical atherosclerosis and insulin resistance. This study examines the predictive roles of trimethylamine N-oxide (TMAO) and resistin in relation to carotid intima-media thickness and metabolic parameters; Methods: Sixty adults (18-71 years) with varying body weights were assessed for body composition, subclinical atherosclerosis, and blood biomarkers, including TMAO and resistin; Results: TMAO correlated strongly with CIMT (r = 0.674, p < 0.001), indicating its role in subclinical atherosclerosis. Logistic regression identified TMAO (threshold 380; AUC = 0.880, accuracy = 91.7%) as a predictor of cardiometabolic risk. Resistin was associated with CIMT, WHR, and total cholesterol, inversely linked to LDL cholesterol (p = 0.003). Less active participants exhibited higher TMAO (p = 0.001) and resistin (p = 0.02). Family histories of obesity and diabetes correlated with elevated TMAO, while resistin linked to shorter sleep duration and diabetes history, highlighting their importance in obesity-related cardiometabolic risks; Conclusions: TMAO is strongly linked to abdominal fat, insulin resistance, and subclinical atherosclerosis, while resistin is associated with lipid metabolism and aging. Their combined assessment enhances the prediction of obesity-related cardiometabolic risk, supporting their role in risk stratification and targeted interventions.

Microbiome-Derived Trimethylamine N-Oxide (TMAO) as a Multifaceted Biomarker in Cardiovascular Disease: Challenges and Opportunities

Biomarkers play a crucial role in various stages of disease management, including screening, diagnosis, prediction, prognosis, treatment, and safety monitoring. Although they are powerful tools in disease diagnosis, management, and drug development, identifying and validating reliable biomarkers remains a significant challenge. Among potential microbiome-derived biomarkers, trimethylamine N-oxide (TMAO) has gained notable attention for its link to atherosclerosis and cardiovascular risk. However, despite the growing body of research on TMAO, its practical application in clinical settings for disease management and patient outcome enhancement is still not a reality. This paper presents recent data on the utility of TMAO as a cardiovascular biomarker, categorized by its various roles: diagnostic, prognostic, susceptibility/risk, monitoring, pharmacodynamic/response, predictive, and safety. It also briefly discusses research on TMAO's potential role in cardiovascular disease development. While TMAO shows promise, particularly in prognostic applications, its reliability as a biomarker has been inconsistent across studies. These variances may result from several confounding factors that affect TMAO plasma levels, including diet, kidney function, and demographic variables. The review aims to elucidate the specific contexts in which TMAO can be valuable, potentially leading to more personalized and effective management of cardiovascular disease.

Gut Microbe-Generated Metabolite Trimethylamine-N-Oxide and Ischemic Stroke

Trimethylamine-N-oxide (TMAO) is a gut microbiota-derived metabolite, the production of which in vivo is mainly regulated by dietary choices, gut microbiota, and the hepatic enzyme flavin monooxygenase (FMO), while its elimination occurs via the kidneys. The TMAO level is positively correlated with the risk of developing cardiovascular diseases. Recent studies have found that TMAO plays an important role in the development of ischemic stroke. In this review, we describe the relationship between TMAO and ischemic stroke risk factors (hypertension, diabetes, atrial fibrillation, atherosclerosis, thrombosis, etc.), disease risk, severity, prognostic outcomes, and recurrence and discuss the possible mechanisms by which they interact. Importantly, TMAO induces atherosclerosis and thrombosis through lipid metabolism, foam cell formation, endothelial dysfunction (via inflammation, oxidative stress, and pyroptosis), enhanced platelet hyper-reactivity, and the upregulation and activation of vascular endothelial tissue factors. Although the pathogenic mechanisms underlying TMAO's aggravation of disease severity and its effects on post-stroke neurological recovery and recurrence risk remain unclear, they may involve inflammation, astrocyte function, and pro-inflammatory monocytes. In addition, this paper provides a summary and evaluation of relevant preclinical and clinical studies on interventions regarding the gut-microbiota-dependent TMAO level to provide evidence for the prevention and treatment of ischemic stroke through the gut microbe-TMAO pathway.

Elevated Circulating Levels of Gut Microbe-Derived Trimethylamine N-Oxide Are Associated with Systemic Sclerosis

Background/Objectives: Alterations in fecal microbial communities in patients with systemic sclerosis (SSc) are common, but the clinical significance of this observation is poorly understood. Gut microbial production of trimethylamine (TMA), and its conversion by the host to trimethylamine N-oxide (TMAO), has clinical and mechanistic links to cardiovascular and renal diseases. Direct provision of TMAO has been shown to promote fibrosis and vascular injury, hallmarks of SSc. We sought to determine levels of TMAO and related metabolites in SSc patients and investigate associations between the metabolite levels with disease features. Methods: This is an observational case:control study. Adults with SSc (n = 200) and non-SSc controls (n = 400) were matched for age, sex, indices of renal function, diabetes mellitus, and cardiovascular disease. Serum TMAO, choline, betaine, carnitine, γ-butyrobetaine, and crotonobetaine were measured using stable isotope dilution liquid chromatography tandem mass spectrometry. Results: Median TMAO concentration was higher (p = 0.020) in SSc patients (3.31 [interquartile range 2.18, 5.23] µM) relative to controls (2.85 [IQR 1.88, 4.54] µM). TMAO was highest among obese and male SSc participants compared to all other groups. Following adjustment for sex, BMI, age, race, and eGFR in a quantile regression model, elevated TMAO levels remained associated with SSc at each quantile of TMAO. Conclusions: Patients with SSc have increased circulating levels of TMAO independent of comorbidities including age, sex, renal function, diabetes mellitus, and cardiovascular disease. As a potentially modifiable factor, further studies examining the link between TMAO and SSc disease severity and course are warranted.

Gut Fungal Microbiota Alterations in Pulmonary Arterial Hypertensive Rats

The gut microbiome's imbalance has been implicated in the pathogenesis of pulmonary arterial hypertension (PAH), yet the contribution of the gut mycobiome remains largely unclear. This study delineates the gut mycobiome profile in PAH and examines its interplay with the bacterial microbiome alterations. Fecal samples from monocrotaline-induced PAH rats and matched controls were subjected to internal transcribed spacer 1 (ITS1) sequencing for fungal community assessment and 16S ribosomal RNA (rRNA) gene sequencing for bacterial community characterization. Comparative analysis revealed no significant disparities in the overall mycobiome diversity between the PAH and control groups. However, taxonomic profiling identified differential mycobiome compositions, with the PAH group exhibiting a significant enrichment of genera such as Wallemia, unidentified_Branch02, Postia, Malassezia, Epicoccum, Cercospora, and Alternaria. Conversely, genera Xeromyces, unidentified_Plectosphaerellaceae, and Monilia were more abundant in the controls. Correlations of Malassezia and Wallemia abundance with hemodynamic parameters were observed. Indications of bidirectional fungal-bacterial community interactions were also noted. This investigation reveals distinct gut mycobiome alterations in PAH, which are intricately associated with concurrent bacterial microbiome changes, suggesting a possible contributory role of gut fungi in PAH pathophysiology. These findings underscore the potential for novel gut mycobiome-targeted therapeutic interventions in PAH management.