A validated simple LC-MS/MS method for quantifying trimethylamine N-oxide (TMAO) using a surrogate matrix and its clinical application

In vivo 2H-MR spectroscopy and imaging of hepatic metabolic formation of trimethylamine-N-oxide

PURPOSE

Despite growing evidence of the link between elevated levels of trimethylamine-N-oxide (TMAO) and multiple diseases, there is no method with which to spatially monitor its hepatic formation from the interstitially produced trimethylamine (TMA). This study aimed to develop a deuterium metabolic spectroscopy (DMS) and imaging (DMI) approach to detect the TMA-to-TMAO metabolism in vivo.

METHODS

The metabolism of 2H9-TMA (TMA-d9) to 2H9-TMAO (TMAO-d9) in cells overexpressing the hepatic enzyme flavin-dependent monooxygenase 3 (FMO3) was monitored in vitro with 2H-NMR. Using an ultrahigh-field (15.2T) MRI scanner, the hepatic metabolism of the orally administered TMA-d9 to TMAO-d9 was studied in mice with DMS and DMI.

RESULTS

The spectrally resolved 2H-NMR peaks of intracellularly produced TMAO-d9 (3.1 ppm) from that of supplemental TMA-d9 (2.7 ppm) could be detected only in cells that overexpressed FMO3. In vivo, DMS and DMI experiments performed after oral administration of TMA-d9 revealed the conversion to high TMAO-d9 levels in the liver of females, which express high levels of FMO3. In contrast, there was no indication of TMAO-d9 production in the liver of males, in agreement with reports of the role of testosterone in downregulating the expression of FMO3.

CONCLUSION

This work shows the ability to use 2H-MR-based methodologies to spatially monitor the TMA-to-TMAO metabolic pathway in vivo, and thus should be explored further to investigate the role of TMAO in diverse pathologies.

Salivary trimethylamine N-oxide: a novel non-invasive marker for periodontal inflammation

OBJECTIVES

Trimethylamine N-oxide (TMAO) has been implicated in systemic inflammatory pathways, emphasizing its potential as a biomarker. Elevated plasma TMAO levels have been associated with increased oxidative stress, leading to higher plasma concentrations of TNF-α, a key pro-inflammatory cytokine. Given this systemic inflammatory linkage, saliva-a non-invasive diagnostic medium-offers a unique opportunity to reflect both local and systemic inflammatory changes. This study aimed to evaluate the alterations in salivary and serum TMAO levels in periodontitis and assess the diagnostic potential of salivary TMAO as an indicator of periodontal inflammation.

MATERIALS AND METHODS

Twenty-four patients with periodontitis (Stage III Grade B) and 24 healthy controls were included. Clinical parameters (probing depth (PD), plaque index (PI), bleeding on probing (BOP), and clinical attachment loss (CAL)) were recorded. TMAO levels in saliva and serum were measured using liquid chromatography-mass spectrometry (LC-MS/MS), and TNF-α levels were assessed using Enzyme-Linked ImmunoSorbent Assay (ELISA).

RESULTS

Salivary and serum TMAO levels and salivary TNF-α levels were significantly higher in the periodontitis group (p = 0.003, p = 0.004, and p = 0.031, respectively). Salivary TMAO showed positive correlations with periodontal parameters (p < 0.05) and salivary TNF-α levels. A significant positive correlation was also observed between salivary and serum TMAO levels (p < 0.001). Salivary TMAO was the accurate biomarker in differentiating between periodontitis and controls (sensitivity = 0.583, specificity = 0.833, AUC = 0.747).

CONCLUSIONS

Salivary TMAO demonstrates potential as a non-invasive marker for periodontitis, showing correlations with clinical parameters and inflammatory markers. These findings suggest that TMAO may reflect both local and systemic inflammatory states associated with periodontal disease.

CLINICAL RELEVANCE

Salivary TMAO may serve as a potential non-invasive indicator of periodontitis, as it reflects aspects of both local and systemic inflammation, offering insights into periodontal disease status.

Trimethylamine N-Oxide (TMAO) and TNF-α Levels in Periodontal Disease Associated With Smoking

AIMS

Trimethylamine N-oxide (TMAO) is a compound involved in the pathogenesis of various systemic inflammatory diseases, including cardiovascular conditions. The aim of this study was to determine differences in saliva and serum levels of TMAO between periodontitis and healthy patients according to smoking status.

METHODS

The study included four systemically healthy groups: periodontally healthy non-smokers (NS-Control; n = 25), non-smokers with Stage-III-Grade-B periodontitis (NS-Periodontitis; n = 25), periodontally healthy smokers (S-Control; n = 25), and smokers with Stage-III Grade-C periodontitis (S-Periodontitis; n = 25). Periodontal parameters were recorded. TMAO levels were determined in saliva and serum samples using liquid chromatography-mass spectrometry (LC-MS/MS). TNF-α levels were measured by the ELISA method.

RESULTS

Salivary TNF-α and TMAO levels were significantly elevated in the smoking periodontitis group compared to other groups (p < 0.001 and p = 0.003, respectively). Serum TMAO levels were also significantly higher in the smoking periodontitis group compared to non-smoking controls and non-smoking periodontitis. TMAO/SFR ratios were notably higher in the smoking periodontitis group compared to other groups, and a strong positive correlation was observed between salivary TMAO and TNF-α levels (r = 0.892, p < 0.001).

CONCLUSION

The data suggested that TMAO and TNF-α are associated with inflammatory mechanisms of periodontitis in cases where periodontitis coexists with smoking.

TRIAL REGISTRATION

NCT06580431.

Reaction-Based Fluorescence Assays for the Determination of Food Trimethylamine Oxide

Trimethylamine oxide (TMAO), a microbial metabolite commonly found in foods, has been attracting increasing attention as it is associated with the risk of several diseases. Simple and accurate analytical methods are crucial for TMAO study. In the present study, we proposed a chemical reaction-based fluorescence assay for TMAO detection using synthetic small molecular probes. After systematic screening and optimization, the sensitive and selective quantification of TMAO has been achieved based on a fluorescence probe P6 (3-iodopropanyl group modified resorufin). Excellent linearity (R2 = 0.997) was found between 6.25 and 50 μM, and the limit of detection (LOD) was 0.20 μM. Using this method, TMAO levels in several marine fishes and shellfishes have been successfully analyzed. The probe-based assay offers a simple and useful way for TMAO determination. The design is inspired by the unique oxidation reaction between TMAO and halogen, which opens a new perspective in the development of more advanced analytical assays for TMAO in the future.

The gut-pancreas axis: investigating the relationship between microbiota metabolites and pancreatic steatosis

The prevalence of pancreatic steatosis has increased and it has been linked to the rising prevalence of metabolic syndrome. Metabolic syndrome is known to have a strong connection with changes in intestinal microbiota. The aim of this study was to explore the relationship between pancreatic steatosis and the levels of trimethylamine N-oxide (TMAO) and butyrate. In this study, 136 individuals were randomly selected from outpatient clinics at Firat University Hospital. The study evaluated their demographic characteristics, anthropometric measurements, and biochemical parameters. The presence of pancreatic steatosis was assessed using abdominal ultrasonography. Additionally, the levels of TMAO and butyrate were measured. The mean age of individuals in the study was 44.5 ± 14.6. 84 of the subjects were females. Using the waist circumference, 61 were considered obese and 34 overweight. The detection rate of pancreatic steatosis was found to be 70.6%. The study found that individuals with steatosis had higher average age, presence of hepatic steatosis, BMI, waist circumference measurements, and presence of metabolic syndrome than those without steatosis. A significantly higher butyrate level was detected in those without steatosis (p = 0.001). TMAO levels were slightly higher in patients without steatosis than in those with steatosis; however, this was insignificant. Pancreatic steatosis is highly associated with alterations in levels of microbiota metabolites, indicating a potential role of these metabolites in the pathogenesis of the disease and subsequent therapeutic targets. Several other factors, such as age, hepatic steatosis, diabetes, and waist circumference, have also been identified as potential predictors of pancreatic steatosis.

Biological Matrix Supply Chain Shortages: More Matrices Are Now Rare-the Case for Surrogate Matrices

The COVID-19 pandemic has strained the biological matrix supply chain. An upsurge in demand driven by numerous COVID-19 therapeutic and vaccine development programs to combat the pandemic, along with logistical challenges sourcing and transporting matrix, has led to increased lead times for multiple matrices. Biological matrix shortages can potentially cause significant delays in drug development programs across the pharmaceutical and biotechnology industry. Given the current circumstances, discussion is warranted around what will likely be increased use of surrogate matrices in support of pharmacokinetic (PK), immunogenicity, and biomarker assays for regulatory filings. Regulatory authorities permit the use of surrogate matrix in bioanalytical methods in instances where matrix is rare or difficult to obtain, as long as the surrogate is appropriately selected and scientifically justified. Herein, the scientific justification and possible regulatory implications of employing surrogate matrix in PK, immunogenicity, and biomarker assays are discussed. In addition, the unique challenges that cell and gene therapy (C&GT) and other innovative therapeutic modalities place on matrix supply chains are outlined. Matrix suppliers and contract research organizations (CROs) are actively implementing mitigation strategies to alleviate the current strain on the matrix supply chain and better prepare the industry for any future unexpected strains. To maintain ethical standards, these mitigation strategies include projecting matrix needs with suppliers at least 6 months in advance and writing or updating study protocols to allow for additional matrix draws from study subjects and/or re-purposing of subject matrix from one drug development program to another.