Juergen Geisel

Plasma trimethylamine N-oxide concentration is associated with choline, phospholipids, and methyl metabolism

BACKGROUND Elevated plasma concentrations of the gut bacteria choline metabolite trimethylamine N-oxide (TMAO) are associated with atherosclerosis. However, the determinants of TMAO in humans require additional assessment. OBJECTIVE We examined cardiometabolic risk factors and pathways associated with TMAO concentrations in humans. DESIGN A total of 283 individuals (mean ± SD age: 66.7 ± 9.0 y) were included in this observational study. Plasma concentrations of trimethylamine, TMAO, choline, lipids, phospholipids, and methyl metabolites were measured. RESULTS Study participants were divided into 4 groups by median concentrations of TMAO and choline (4.36 and 9.7 μmol/L, respectively). Compared with the group with TMAO and choline concentrations that were less than the median (n = 82), the group with TMAO and choline concentrations that were at least the median (n = 83) was older and had lower high-density lipoprotein (HDL) cholesterol, phospholipids, and methylation potential, higher creatinine, betaine, S-adenosylhomocysteine (SAH), and S-adenosylmethionine (SAM), and higher percentages of men and subjects with diabetes. The difference in plasma TMAO concentrations between men and women (7.3 ± 10.0 compared with 5.4 ± 5.6 μmol/L, respectively) was NS after adjustment for age and creatinine (P = 0.455). The TMAO:trimethylamine ratio was higher in men (P < 0.001). Diabetes was associated with significantly higher plasma TMAO concentration (8.6 ± 12.2 compared with 5.4 ± 5.2 μmol/L) even after adjustments. Sex and diabetes showed an interactive effect on trimethylamine concentrations (P = 0.010) but not on TMAO concentrations (P = 0.950). Positive determinants of TMAO in a stepwise regression model that applied to the whole group were SAH, trimethylamine, choline, and female sex, whereas plasma phosphatidylcholine was a negative determinant. CONCLUSIONS High TMAO and choline concentrations are associated with an advanced cardiometabolic risk profile. Diabetes is related to higher plasma TMAO concentrations but also to alterations in interrelated pathways such as lipids, phospholipids, and methylation. Elevated plasma TMAO concentrations likely reflect a specific metabolic pattern characterized by low HDL and phospholipids in addition to hypomethylation. This trial was registered at clinicaltrials.gov as NCT02586181 and NCT02588898.

The role of choline in prostate cancer.

Choline is an essential nutrient that is necessary for cell membrane synthesis and phospholipid metabolism and functions as an important methyl donor. Multiple roles for choline in cancer development have been suggested. Choline can affect DNA methylation and lead to a disruption of DNA repair. It can also modify cell signaling that is mediated by intermediary phospholipid metabolites, and it can support the synthesis of cell membranes and thus support cell proliferation. A higher intake or status of choline in plasma and tissues has been related to higher cancer risks. Prostate cancer shows elevated levels of choline uptake and levels of certain choline metabolites. Choline metabolites can be used as potential prognostic biomarkers for the management of prostate cancer patients. Targeting certain enzymes, which are related to choline metabolism, provides promising therapeutic opportunities for tumor growth arrest. This review summarizes the potential role of choline metabolism in cancer, especially in prostate cancer.

Measurement of concentrations of whole blood levels of choline, betaine, and dimethylglycine and their relations to plasma levels.

We aimed at developing a method for the measurement of choline and its metabolites in whole blood (WB). After an extraction step, quantification of choline, betaine, and dimethylglycine (DMG) was performed using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Plasma and WB metabolites were evaluated in a group of 61 elderly people. The calibration curves were linear (r(2)>0.997) for all compounds. The inter- and intra-assay coefficients of variation for all analytes were <10%. The recoveries were >90% and the relative matrix effect were ≤4.0%. The median concentrations of choline, betaine, and DMG were 11.3, 27.8, and 5.9μmol/L in plasma and 66.6, 165, and 13.7μmol/L in WB, respectively. There were positive correlations between WB and plasma markers; for choline (r=0.42), betaine (r=0.61), and DMG (r=0.56) (all p≤0.001). The concentrations of betaine in WB and plasma were significantly higher in men than in women. The concentrations of WB choline and DMG did not differ significantly according to sex. In conclusion, we have established a reliable method for measuring choline metabolites in WB. The concentrations of WB choline, betaine, and DMG seem to reflect intracellular concentrations of these metabolites.

Determination of trimethylamine, trimethylamine N-oxide, and taurine in human plasma and urine by UHPLC-MS/MS technique.

BACKGROUND Trimethylamine-N-oxide (TMAO) is produced in the liver from trimethylamine (TMA) and is an important cellular osmolyte and potential atherogenic factor. Taurine is involved in cholesterol metabolism and also serves as a cellular osmolyte. Given their significant biological functions, the development of reliable measurement techniques is crucial to further study their role in health and disease METHODS: A new ultrahigh performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of TMA, TMAO, and taurine in plasma and urine. The method consisted of a deproteinization step using methanol/acetonitrile (15:85) that contained 0.2% formic acid and isotope-labeled internal standards. Samples were separated by centrifugation and injected into the UHPLC system. Quantification was conducted using a triple-quadrupole mass spectrometer detector with electrospray ionization interface in positive mode. RESULTS The limits of detection ranged from 0.08 to 0.12μmol/L. The calibration curves were linear (r≥0.999) over the range examined (0.15-400μmol/L) for all compounds. The inter- and intra-day coefficients of variations were≤14.5% for TMA and ≤8% for TMAO and taurine. TMAO and taurine were found to be stable in EDTA plasma for at least 14 months at -70°C. Mean recoveries ranged from 95% to 109% and the relative matrix effects were≤4.0%. The method was applied to study physiological and pre-analytical factors in plasma and urine samples. CONCLUSIONS The new UHPLC-MS/MS method has good accuracy, precision, and recovery. The assay combines simple sample processing with a short run time, making it well suited for high-throughput routine clinical or research purposes.

Plasma trimethylamine‐N‐oxide following supplementation with vitamin D or D plus B‐vitamins

SCOPE We compared the effect of supplementation with vitamin D + B or vitamin D on plasma trimethylamine N-oxide (TMAO) and choline metabolites. METHODS AND RESULTS This is a randomized single-blinded nonplacebo-controlled study. Twenty-seven participants received 1200 IU vitamin D3 and 800 mg calcium, and 25 participants received additionally 0.5 mg folic acid, 50 mg B6, and 0.5 mg B12 for 1 year. Plasma homocysteine (Hcy), TMAO, and choline metabolites were measured at baseline and 12 months later. TMAO declined in the vitamin D arm by 0.5 versus 2.8 μmol/L in the D + B arm (p = 0.005). Hcy decreased and betaine increased in the D + B compared to the D arm. Within-subject levels of plasma choline and dimethylglycine and urine betaine increased in both arms and changes did not differ between the arms. TMAO reduction was predicted by higher baseline TMAO and lowering Hcy in stepwise regression analysis. The test-retest variations of TMAO were greater in the D + B arm compared to vitamin D arm. CONCLUSION B vitamins plus vitamin D lowered plasma fasting TMAO compared to vitamin D. Vitamin D caused alterations in choline metabolism, which may reflect the metabolic flexibility of C1-metabolism. The molecular mechanisms and health implications of these changes are currently unknown.

Vitamin B-12–fortified toothpaste improves vitamin status in vegans: a 12-wk randomized placebo-controlled study

Background: The oral application of vitamin B-12 may prevent its deficiency if the vitamin is absorbed via the mucosal barrier.Objectives: We studied the effect of the use of a vitamin B-12-fortified toothpaste on vitamin-status markers in vegans and assessed the efficiency of markers in the identification of vitamin-augmentation status.Design: In this 12-wk, double-blinded, randomized, placebo-controlled study, 76 vegans received either a placebo (n = 34) or vitamin B-12 (n = 42) toothpaste. Sixty-six subjects (n = 30 in the placebo arm; n = 36 in the vitamin B-12 arm) completed the intervention. Serum and plasma concentrations of vitamin B-12, holotranscobalamin, total homocysteine (tHcy), and methylmalonic acid (MMA) were measured before and after the intervention.Results: Both postintervention concentrations of vitamin B-12 and holotranscobalamin and their changes over 12 wk were higher in the vitamin B-12 group (mean ± SD change: 81 ± 135 pmol/L for vitamin B-12 and 26 ± 34 pmol/L for holotranscobalamin) than in the placebo group (-27 ± 64 and -5 ± 17 pmol/L, respectively) after adjustment for baseline concentrations. Postintervention concentrations of MMA and their changes differed significantly between groups (MMA changes: -0.169 ± 0.340 compared with -0.036 ± 0.544 μmol/L in vitamin B-12 and placebo groups, respectively; P < 0.001). After adjustment for baseline tHcy, postintervention concentrations of tHcy tended to be lower (P = 0.051), and the changes in tHcy (-0.7 ± 4.4 compared with 2.0 ± 5.6 μmol/L, respectively) were greater in the vitamin B-12 group than in the placebo group. Changes in vitamin B-12 markers were more prominent in vegans who reported that they had not taken vitamin B-12 supplements.Conclusion: Vitamin B-12 that is applied to the oral cavity via toothpaste enters the circulation and corrects the vitamin B-12 markers in the blood of vegans who are at higher risk of vitamin B-12 deficiency. This trial was registered at clinicaltrials.gov as NCT02679833.

Probiotics Affect One-Carbon Metabolites and Catecholamines in a Genetic Rat Model of Depression

Scope Probiotics may influence one‐carbon (C1) metabolism, neurotransmitters, liver function markers, or behavior. Methods and results Male adult Flinders Sensitive Line rats (model of depression, FSL; n = 22) received Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 (109 or 1010 colony‐forming units per day) or vehicle for 10 weeks. The controls, Flinders Resistant Line rats (FRL, n = 8), only received vehicle. C1‐related metabolites were measured in plasma, urine, and different tissues. Monoamine concentrations were measured in plasma, hippocampus, and prefrontal cortex. Vehicle‐treated FSL rats had higher plasma concentrations of betaine, choline, and dimethylglycine, but lower plasma homocysteine and liver S‐adenosylmethionine (SAM) than FRLs. FSL rats receiving high‐dose probiotics had lower plasma betaine and higher liver SAM compared to vehicle‐treated FSL rats. FSLs had higher concentrations of norepinephrine, dopamine, and serotonin than FRLs across various brain regions. Probiotics decreased plasma dopamine in FSLs in a dose‐dependent manner. There were no detectable changes in liver function markers or behavior. Conclusions Probiotics reduced the flow of methyl groups via betaine, increased liver SAM, and decreased plasma dopamine and norepinephrine. Since these changes in methylation and catecholamine pathways are known to be involved in several diseases, future investigation of the effect of probiotics is warranted.

Serum concentrations of folate vitamers in patients with a newly diagnosed prostate cancer or hyperplasia

BACKGROUND Folate is required for synthesis of methyl groups and DNA in growing cells. The association between folate and prostate cancer (PCa) is not conclusive. METHODS We investigated concentrations of folate vitamers, S-adenosylhomocysteine (SAH) and S-adenosylmethionine (SAM) in blood of men with PCa (n = 129) or benign prostatic hyperplasia (BPH) (n = 73) who were recruited just after the first diagnosis. RESULTS In younger subjects <65 years, concentrations of (6S)-5-CH3-H4folate (15.3 vs. 17.7 nmol/L) or total folate (UPLC-MS/MS) (18.7 vs. 23.0 nmol/L) did not differ between men with BPH and those with PCa, while SAM was higher in the controls (128 vs. 116 nmol/L). Younger patients with low- and high grade cancer did not differ in (6S)-5-CH3-H4folate (17.8 vs. 17.3 nmol/L) or total folate (UPLC-MS/MS) (22.9 vs. 23.3 nmol/L), but SAM was lower in patients with low grade PCa (111 vs. 126 nmol/L). In the older group ≥65 years, (6S)-5-CH3-H4folate (18.4 vs. 18.2 nmol/L) and total folate (UPLC-MS/MS) (22.5 vs. 22.1 nmol/L) did not differ between BPH and PCa. Older patients with advanced tumors had lower (6S)-5-CH3-H4folate compared with those with low grade tumor (12.8 vs. 20.0 nmol/L: p = 0.013). Plasma SAM was not different between older patients and controls and was not related to PCa grade. CONCLUSIONS Lowered serum methyl folate measured at the time of diagnosis in older patients with advanced PCa, and lowered plasma SAM in younger patients with low grade PCa suggest differential folate metabolism that may have mechanistic, prognostic or predictive values.