Stefan Graeber

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.

Low serum folate and vitamin B-6 are associated with an altered cancellous bone structure in humans.

BACKGROUND Several clinical trials have reported B vitamins to be associated with osteoporosis. OBJECTIVE Our objective was to investigate whether low serum B vitamins are associated with altered structural and biomechanical properties of human bone. DESIGN Femoral heads of 94 men and women who underwent hip arthroplasty were analyzed by using dual-energy X-ray absorptiometry (DXA), biomechanical testing (indentation method), and histomorphometry. In addition, blood was collected to measure serum concentrations of homocysteine, folate, vitamin B-6, vitamin B-12, the bone formation marker osteocalcin, and the bone resorption marker tartrate-resistant acid phosphatase (TRAP). Measurement outcomes were grouped according to subjects with high and low serum concentrations, respectively, of folate, vitamin B-6, and vitamin B-12 (n = 47 for each group). RESULTS Histomorphometric analysis showed a significantly lower trabecular thickness and trabecular area in subjects with low serum folate concentrations than in those with high serum folate concentrations and a significantly lower trabecular number in subjects with low serum vitamin B-6 concentrations than in those with high serum vitamin B-6 concentrations. In contrast, we found a comparable trabecular structure in subjects with high and low serum vitamin B-12 concentrations. DXA and biomechanical testing did not show significant differences between subjects with high and low serum B vitamin concentrations. Osteocalcin was significantly lowered in subjects with a low serum B vitamin concentration, whereas there was no association between serum B vitamins and TRAP. CONCLUSION The results of the present study indicate that low serum folate and vitamin B-6 concentrations, but not low serum vitamin B-12 concentrations, are associated with an altered morphology of human bone.

Genetic polymorphism of the OPG gene associated with breast cancer

BackgroundThe receptor activator of NF-κB (RANK), its ligand (RANKL) and osteoprotegerin (OPG) have been reported to play a role in the pathophysiological bone turnover and in the pathogenesis of breast cancer. Based on this we investigated the role of single nucleotide polymorphisms (SNPs) within RANK, RANKL and OPG and their possible association to breast cancer risk.MethodsGenomic DNA was obtained from Caucasian participants consisting of 307 female breast cancer patients and 396 gender-matched healthy controls. We studied seven SNPs in the genes of OPG (rs3102735, rs2073618), RANK (rs1805034, rs35211496) and RANKL (rs9533156, rs2277438, rs1054016) using TaqMan genotyping assays. Statistical analyses were performed using the χ2-tests for 2 x 2 and 2 x 3 tables.ResultsThe allelic frequencies (OR: 1.508 CI: 1.127-2.018, p=0.006) and the genotype distribution (p=0.019) of the OPG SNP rs3102735 differed significantly between breast cancer patients and healthy controls. The minor allele C and the corresponding homo- and heterozygous genotypes are more common in breast cancer patients (minor allele C: 18.4% vs. 13.0%; genotype CC: 3.3% vs. 1.3%; genotype CT: 30.3% vs. 23.5%). No significantly changed risk was detected in the other investigated SNPs. Additional analysis showed significant differences when comparing patients with invasive vs. non-invasive tumors (OPG rs2073618) as well as in terms of tumor localization (RANK rs35211496) and body mass index (RANKL rs9533156 and rs1054016).ConclusionsThis is the first study reporting a significant association of the SNP rs3102735 (OPG) with the susceptibility to develop breast cancer in the Caucasian population.

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.

Predictive value of soluble ST2 in adolescent and adult patients with complex congenital heart disease

Background Soluble suppression of tumorogenicity 2 (sST2) has been shown to be of prognostic value in patients with chronic and acute left heart failure. The present study aims to assess the predictive value of sST2 levels in adult patients with complex congenital heart disease (CHD). Methods In 169 consecutive patients with complex CHD and a mean age of 28.2 ± 12.0 years, sST2 levels were compared to 32 healthy controls and associated with clinical status as well as the occurrence of major adverse cardiac events (MACE). Mean follow-up time was 35.6 ± 24.9 months. Results In CHD patients, median sST2 levels were 29.7 ng/ml compared to 26.4 ng/ml in healthy controls (p = 0.007) and increased with different types of CHD and the severity of MACE. According to ROC analysis, the most important predictors of acute heart/Fontan failure were NYHA class III/IV (AUC 0.804, p<0.001, CI 0.668–0.941), NT-proBNP levels (AUC 0.794, p<0.001, CI 0.640–0.948), γGT levels (AUC 0.793, p<0.001, CI 0.678–0.909) and sST2 levels (AUC 0.742, p = 0.004, CI 0.626–0.858), with NYHA class III/IV as the strongest independent predictor (p<0.001). All-cause mortality was best predicted by sST2 levels (AUC 0.890, p<0.001, CI 0.741–1.000), NT-proBNP levels (AUC 0.875, p = 0.001, CI 0.766–0.984) and NYHA class III/IV (AUC 0.837, p = 0.003, CI 0.655–1.000) with sST2 as the strongest independent predictor (p<0.001). Moreover, AUC increased to 0.918 combining both biomarkers and net reclassification improved with the addition of sST2. Conclusion In patients with complex CHD, sST2 may have additive value to natriuretic peptides for the prediction of all-cause mortality.