MTHFR 677 C>T Polymorphism reveals functional importance for 5-methyltetrahydrofolate, not homocysteine, in regulation of vascular redox state and endothelial function in human atherosclerosis

Association of plasma homocysteine with peripheral arterial disease in the hypertensive adults: A cross-sectional study

Increased plasma homocysteine (Hcy) has been identified as one of the important risk factors for cardiovascular disease. However, the association between plasma Hcy and peripheral artery disease (PAD) is still controversial. This study aimed to investigate the association between plasma Hcy and PAD and the potential modifier factors in Chinese hypertensive adults. A total of 25 300 hypertensive patients aged 18 years or older were included in the analysis in this cross-sectional study. The outcome was PAD, which defined as an ankle-brachial index ≤0.90 in either limb. Multiple logistic regression was used to analyze the relationship between plasma Hcy and PAD. The median plasma Hcy was 14.00 (interquartile range: 11.60-17.80) μmol/L. There was a significant positive association between plasma Hcy and PAD (per SD increment; OR: 1.13; 95% CI: 1.06-1.19). Patients in the upper plasma Hcy tertile (≥16.16 μmol/L) were associated with a 53% increased risk of PAD compared with patients in the lower tertile (<12.33 μmol/L) after adjustment for multiple potential confounders. Subgroup analyses showed the association between Hcy and PAD was robust among various strata. Among Chinese adults with hypertension, plasma Hcy is an independent risk factor for PAD. This finding may improve the risk stratification of PAD.

Homozygous MTHFR C667T carriers ≤45 years old develop central retinal vein occlusion five years earlier than wild type

PURPOSE

To assess age at 1st central retinal vein occlusion (CRVO) in carriers ≤ 45 years old of the methylenetetrahydrofolate reductase (MTHFR) C667T genotype compared to heterozygous and wild type, and to identify predictors of age at CRVO.

METHODS

Retrospective cohort study consisting of 18 MTHFR TT, 23 MTHFR TC and 28 MTHFR CC participants; information regarding age, sex, age at CRVO, history of dyslipidaemia, hypertension, smoking and plasma HC measured by immunoassay were collected.

RESULTS

Age at CRVO was lower in MTHFR TT than MTHFR TC and CC (32 ± 6 vs 38 ± 5 vs 37 ± 6 years, respectively, p = 0.005); plasma HC was higher in MTHFR TT than in the other genotypes [14.4 (10.8, 19.6) vs 10.4 ((8.6,12.5) vs 8.5 ((7.5,9.8) μmol/l, p = 0.0002). Smoking (cigarettes/day) independently predicted age at CRVO (p = 0.039) and plasma HC (p = 0.005); smoking status (yes/no) predicted ischemic CRVO (p = 0.01) that was more common in the MTHFR TT group (p = 0.006).

CONCLUSIONS

Carriers of the MTHFR TT genotype ≤ 45 years old develop their 1st CRVO on average 5 years earlier than the MTHFR CC genotype; smoking contributes to the prematurity and severity of CRVO in MTHFR TT carriers.

Cysteine-lowering treatment with mesna against obesity: Proof of concept and results from a human phase I, dose-finding study

AIM

To investigate whether mesna-sodium-2-mercaptoethane sulfonate) can reduce diet-induced fat gain in mice, and to assess the safety of single ascending mesna doses in humans to find the dose associated with lowering of plasma tCys by at least 30%.

METHODS

C3H/HeH mice were shifted to a high-fat diet ± mesna in drinking water; body composition was measured at weeks 0, 2 and 4. In an open, phase I, single ascending dose study, oral mesna (400, 800, 1200, 1600 mg) was administered to 17 men with overweight or obesity. Mesna and tCys concentrations were measured repeatedly for a duration of 48 hours postdosing in plasma, as well as in 24-hour urine.

RESULTS

Compared with controls, mesna-treated mice had lower tCys and lower estimated mean fat mass gain from baseline (week 2: 4.54 ± 0.40 vs. 6.52 ± 0.36 g; week 4: 6.95 ± 0.35 vs. 8.19 ± 0.34 g; Poverall  = .002), but similar lean mass gain. In men with overweight, mesna doses of 400-1600 mg showed dose linearity and were well tolerated. Mesna doses of 800 mg or higher decreased plasma tCys by 30% or more at nadir (4h post-dosing). With increasing mesna dose, tCys AUC0-12h decreased (Ptrend  < .001), and urine tCys excretion increased (Ptrend  = .004).

CONCLUSIONS

Mesna reduces diet-induced fat gain in mice. In men with overweight, single oral doses of mesna (800-1600 mg) were well tolerated and lowered plasma tCys efficiently. The effect of sustained tCys-lowering by repeated mesna administration on weight loss in humans deserves investigation.

Association of Long-term Exposure to Air Pollution and Dementia Risk: The Role of Homocysteine, Methionine, and Cardiovascular Burden

BACKGROUND AND OBJECTIVES

Growing evidence links air pollution with dementia risk, but the biological mechanisms are largely unknown. We investigated the role played by homocysteine (tHcy) and methionine in this association and explored whether this could be explained by cardiovascular diseases (CVDs).

METHODS

Data were extracted from the ongoing Swedish National study on Aging and Care in Kungsholmen (SNAC-K), a longitudinal population-based study. At baseline, 2,512 dementia-free participants were examined up to 2013 (mean follow-up: 5.18 ± 2.96 years). Two air pollutants (particulate matter ≤2.5 μm [PM2.5] and nitrogen oxides [NOx]) were assessed yearly from 1990 until 2013 using dispersion models at residential addresses. The hazard ratio of dementia over air pollution levels was estimated using Cox models adjusted for age, sex, education, smoking, socioeconomic status, physical activity, retirement age, creatinine, year of assessment, and the use of supplements. The total effect of air pollutants on dementia was decomposed into 4 pathways involving tHcy/methionine: (1) direct effect; (2) indirect effect (mediation); (3) effect due to interaction; and (4) effect due to both mediation and interaction. To test whether the association was independent from CVDs (ischemic heart disease, atrial fibrillation, heart failure, and stroke), we repeated the analyses excluding those individuals who developed CVDs.

RESULTS

The mean age of the study participants was 73.4 years (SD: 10.4), and 62.1% were female individuals. During an average period of 5 years (mean: 5.18; SD: 2.96 years), 376 cases with incident dementia were identified. There was a 70% increased hazard of dementia per unit increase of PM2.5 during the 5 years before baseline (hazard ratio [HR]: 1.71; 95% CI 1.33-2.09). Overall, 50% (51.6%; 95% CI 9.0-94.1) of the total effect of PM2.5 on dementia was due to mediation of tHcy (6.6%; 95% CI 1.6-11.6) and/or interaction (47.8%; 95% CI 4.9-91.7) with tHcy and 48.4% (p = 0.03) to the direct effect of PM2.5 on dementia. High levels of methionine reduced the dementia hazard linked to PM2.5 by 31% (HR: 0.69; 95% CI 0.56-0.85) with 24.8% attributable to the interaction with methionine and 25.9% (p = 0.001) to the direct effect of PM2.5. No mediation effect was found through methionine. Attenuated results were obtained for NOx. Findings for tHcy were attenuated after excluding those who developed CVDs, while remained similar for methionine.

DISCUSSION

High levels of homocysteine enhanced the dementia risk attributed to air pollution, while high methionine concentrations reduced this risk. The impact of homocysteine on cardiovascular conditions partly explains this association. Alternative pathways other than cardiovascular mechanisms may be at play between methionine and dementia.

The Associations of Habitual Intake of Sulfur Amino Acids, Proteins and Diet Quality with Plasma Sulfur Amino Acid Concentrations: The Maastricht Study

BACKGROUND

Plasma sulfur amino acids (SAAs), i.e., methionine, total cysteine (tCys), total homocysteine (tHcy), cystathionine, total glutathione (tGSH), and taurine, are potential risk factors for obesity and cardiometabolic disorders. However, except for plasma tHcy, little is known about how dietary intake modifies plasma SAA concentrations.

OBJECTIVE

To investigate whether the intake of SAAs and proteins or diet quality is associated with plasma SAAs.

METHODS

Data from a cross-sectional subset of The Maastricht Study (n = 1145, 50.5% men, 61 interquartile range: [55, 66] y, 22.5% with prediabetes and 34.3% with type 2 diabetes) were investigated. Dietary intake was assessed using a validated food frequency questionnaire. The intake of SAAs (total, methionine, and cysteine) and proteins (total, animal, and plant) was estimated from the Dutch and Danish food composition tables. Diet quality was assessed using the Dutch Healthy Diet Index, the Mediterranean Diet Score, and the Dietary Approaches to Stop Hypertension score. Fasting plasma SAAs were measured by liquid chromatography (LC) tandem mass spectrometry (MS) (LC/MS-MS). Associations were investigated with multiple linear regressions with tertiles of dietary intake measures (main exposures) and z-standardized plasma SAAs (outcomes).

RESULTS

Intake of total SAAs and total proteins was positively associated with plasma tCys and cystathionine. Associations were stronger in women and in those with normal body weight. Higher intake of cysteine and plant proteins was associated with lower plasma tHcy and higher cystathionine. Higher methionine intake was associated with lower plasma tGSH, whereas cysteine intake was positively associated with tGSH. Higher intake of methionine and animal proteins was associated with higher plasma taurine. Better diet quality was consistently related to lower plasma tHcy concentrations, but it was not associated with the other SAAs.

CONCLUSION

Targeted dietary modifications might be effective in modifying plasma concentrations of tCys, tHcy, and cystathionine, which have been associated with obesity and cardiometabolic disorders.

ALDH2 rs671 and MTHFR rs1801133 polymorphisms are risk factors for arteriosclerosis in multiple arteries

BACKGROUND

Arteriosclerosis in multiple arteries has long been associated with heightened cardiovascular risk. Acetaldehyde dehydrogenase 2 (ALDH2) and methylenetetrahydrofolate reductase (MTHFR) play an important role in the pathogenesis of arteriosclerosis by participating in the oxidation and reduction reactions in vascular endothelial cells. The purpose was to investigate the relationship of ALDH2 and MTHFR gene polymorphisms with arteriosclerosis in multiple arteries.

METHODS

410 patients with arteriosclerosis in single artery and 472 patients with arteriosclerosis in multiple arteries were included. The relationship between ALDH2 rs671 and MTHFR rs1801133 polymorphisms and arteriosclerosis in single artery and arteriosclerosis in multiple arteries was analyzed.

RESULTS

The proportion of ALDH2 rs671 A allele (35.6% vs. 30.9%, P = 0.038) and MTHFR rs1801133 T allele (32.6% vs. 27.1%, P = 0.012) in patients with arteriosclerosis in multiple arteries was significantly higher than that in arteriosclerosis in single artery, respectively. The proportion of history of alcohol consumption in patients with ALDH2 rs671 G/G genotype was higher than those in ALDH2 rs671 G/A genotype and A/A genotype (P < 0.001). The results of logistic regression analysis indicated that ALDH2 rs671 A/A genotype (A/A vs. G/G: OR 1.996, 95% CI: 1.258-3.166, P = 0.003) and MTHFR rs1801133 T/T genotype (T/T vs. C/C: OR 1.943, 95% CI: 1.179-3.203, P = 0.009) may be independent risk factors for arteriosclerosis in multiple arteries (adjusted for age, sex, smoking, drinking, hypertension, and diabetes).

CONCLUSIONS

ALDH2 rs671 A/A and MTHFR rs1801133 T/T genotypes may be independent risk factors for arteriosclerosis in multiple arteries.

Maternal nutrition and effects on offspring vascular function

Maternal nutrition during pregnancy may have profound effects on the developing fetus and impact risk for cardiovascular disease later in life. Here, we provide a narrative review on the impact of maternal diet during pregnancy on offspring vascular function. We review studies reporting effects of maternal micronutrient (folic acid, iron) intakes, high-fat diets, dietary energy restriction, and low protein intake on offspring endothelial function. We discuss the differences in study design and outcomes and potential underlying mechanisms contributing to the vascular phenotypes observed in the offspring. We further highlight key gaps in the literature and identify targets for future investigations.

Biological Role of Folic Acid in Pregnancy and Possible Therapeutic Application for the Prevention of Preeclampsia

The rationale and importance of folic acid supplementation during pregnancy for fetal congenital defect prevention are accepted worldwide. Moreover, a sufficient plasma concentration of folates can reduce the incidence of spontaneous abortions, and support the normal expansion of placental blood vessels, ensuring physiological placental blood flow, thus promoting appropriate fetal growth and development. Furthermore, there is emerging evidence that long-term supplementation with folic acid can effectively prevent preeclampsia. Preeclampsia is unique to the human species in complications during pregnancy, which contributes to maternal and perinatal mortality worldwide. In the pathogenesis of preeclampsia abnormal placental invasion, the excess of antiangiogenic factors and maternal-placental syndrome play a key role. Increased blood levels of homocysteine during pregnancy are associated with the risk of preeclampsia. Moreover, hyperhomocysteinemia has been proposed to be an independent risk factor for preeclampsia. Folate supplementation helps to decrease elevated levels of homocysteine; thus, the role of folic acid supplementation in pregnancy is even more important. Multiple reports suggest that folate administration decreases the level of serum homocysteine and, therefore, reduce the risk and severity of preeclampsia. However, the association between folic acid supplementation and the decreased risk of preeclampsia has been investigated with controversial conclusions. Currently, the optimal dose of folic acid that is effective for preeclampsia prevention remains uncertain. In this review, we aim to summarize the accumulated knowledge on the role of folic acid in the pathogenesis of preeclampsia, and the possible impact of folate supplementation on the decreased risk of preeclampsia.

Associations between plasma sulfur amino acids and specific fat depots in two independent cohorts: CODAM and The Maastricht Study

PURPOSE

Sulfur amino acids (SAAs) have been associated with obesity and obesity-related metabolic diseases. We investigated whether plasma SAAs (methionine, total cysteine (tCys), total homocysteine, cystathionine and total glutathione) are related to specific fat depots.

METHODS

We examined cross-sectional subsets from the CODAM cohort (n = 470, 61.3% men, median [IQR]: 67 [61, 71] years) and The Maastricht Study (DMS; n = 371, 53.4% men, 63 [55, 68] years), enriched with (pre)diabetic individuals. SAAs were measured in fasting EDTA plasma with LC-MS/MS. Outcomes comprised BMI, skinfolds, waist circumference (WC), dual-energy X-ray absorptiometry (DXA, DMS), body composition, abdominal subcutaneous and visceral adipose tissues (CODAM: ultrasound, DMS: MRI) and liver fat (estimated, in CODAM, or MRI-derived, in DMS, liver fat percentage and fatty liver disease). Associations were examined with linear or logistic regressions adjusted for relevant confounders with z-standardized primary exposures and outcomes.

RESULTS

Methionine was associated with all measures of liver fat, e.g., fatty liver disease [CODAM: OR = 1.49 (95% CI 1.19, 1.88); DMS: OR = 1.51 (1.09, 2.14)], but not with other fat depots. tCys was associated with overall obesity, e.g., BMI [CODAM: β = 0.19 (0.09, 0.28); DMS: β = 0.24 (0.14, 0.34)]; peripheral adiposity, e.g., biceps and triceps skinfolds [CODAM: β = 0.15 (0.08, 0.23); DMS: β = 0.20 (0.12, 0.29)]; and central adiposity, e.g., WC [CODAM: β = 0.16 (0.08, 0.25); DMS: β = 0.17 (0.08, 0.27)]. Associations of tCys with VAT and liver fat were inconsistent. Other SAAs were not associated with body fat.

CONCLUSION

Plasma concentrations of methionine and tCys showed distinct associations with different fat depots, with similar strengths in the two cohorts.

Cysteine restriction-specific effects of sulfur amino acid restriction on lipid metabolism

Decreasing the dietary intake of methionine exerts robust anti-adiposity effects in rodents but modest effects in humans. Since cysteine can be synthesized from methionine, animal diets are formulated by decreasing methionine and eliminating cysteine. Such diets exert both methionine restriction (MR) and cysteine restriction (CR), that is, sulfur amino acid restriction (SAAR). Contrarily, SAAR diets formulated for human consumption included cysteine, and thus might have exerted only MR. Epidemiological studies positively correlate body adiposity with plasma cysteine but not methionine, suggesting that CR, but not MR, is responsible for the anti-adiposity effects of SAAR. Whether this is true, and, if so, the underlying mechanisms are unknown. Using methionine- and cysteine-titrated diets, we demonstrate that the anti-adiposity effects of SAAR are due to CR. Data indicate that CR increases serinogenesis (serine biosynthesis from non-glucose substrates) by diverting substrates from glyceroneogenesis, which is essential for fatty acid reesterification and triglyceride synthesis. Molecular data suggest that CR depletes hepatic glutathione and induces Nrf2 and its downstream targets Phgdh (the serine biosynthetic enzyme) and Pepck-M. In mice, the magnitude of SAAR-induced changes in molecular markers depended on dietary fat concentration (60% fat >10% fat), sex (males > females), and age-at-onset (young > adult). Our findings are translationally relevant as we found negative and positive correlations of plasma serine and cysteine, respectively, with triglycerides and metabolic syndrome criteria in a cross-sectional epidemiological study. Controlled feeding of low-SAA, high-polyunsaturated fatty acid diets increased plasma serine in humans. Serinogenesis might be a target for treating hypertriglyceridemia.

MTHFR epigenetic derepression protects against diabetes cardiac fibrosis

BACKGROUND

Diabetes cardiac fibrosis is associated with altered DNA methylation of fibrogenic genes; however, the underlying mechanisms remain unclear.

OBJECTIVES

In this study, we investigate the critical role of DNA methylation aberration-associated suppression of MTHFR in diabetes cardiac fibrosis, and the protective effects of folate on diabetes cardiac fibrosis, using cultured cells, animal models, and clinical samples.

METHODS AND RESULTS

Herein, we report that DNA methylation repression of MTHFR, critically involved in diabetes cardiac fibrosis, mediates the significant protective effects of folate in a mouse model of diabetes cardiac fibrosis induced by STZ. Heart MTHFR expression was markedly suppressed in diabetes cardiac fibrosis patients and mice, accompanied by increased DNMT3A and MTHFR promoter methylation. Knockdown of DNMT3A demethylated MTHFR promoter, recovered the MTHFR loss, and alleviated the diabetes cardiac fibrosis pathology and cardiac fibroblasts pyroptosis. Mechanistically, DNMT3A epigenetically repressed MTHFR expression via methylation of the promoter. Interestingly, folate supplementation can rescue the effect of MTHFR loss in diabetes cardiac fibrosis, suggesting that inactivation of MTHFR through epigenetics is a critical mediator of diabetes cardiac fibrosis.

CONCLUSIONS

The current study identifies that MTHFR repression due to aberrant DNMT3A elevation and subsequent MTHFR promoter hypermethylation is likely an important epigenetic feature of diabetes cardiac fibrosis, and folate supplementation protects against diabetes cardiac fibrosis.

B-vitamins and homocysteine as determinants of bone health: a literature review of human studies

Although there are several factors related to bone diseases such as physical activity, gender (oestrogen), race/ethnicity, smoking and alcohol habits, nutrition is a modifiable risk factor that could be employed to prevent or manage the onset of bone health diseases such as osteoporosis in humans. Aside from calcium and vitamin D, B-vitamins are a group of water-soluble vitamins that play a vital role in cell metabolism. In this review, current evidence on B-vitamins and bone health was assessed. Clinical trials (interventions) indicated that treatment with B-vitamins impact the concentrations of total plasma/serum homocysteine concentrations (tHcy), however, most studies reported a lack of an effect of low homocysteine concentrations on bone turnover markers, bone mineral density (BMD) or fracture risks. Current studies have been inconsistent in their reports on the role of B-vitamins and homocysteine in bone health. More data are therefore required to show the mechanism and effect of tHcy and B-vitamins on BMD, bone metabolism and fracture risk. This article is protected by copyright. All rights reserved.

Impact of the MTHFR C677T polymorphism on blood pressure and related central hemodynamic parameters in healthy adults

BACKGROUND

The C677T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR) is associated with an increased risk of hypertension and cardiovascular disease. Riboflavin, the MTHFR cofactor, is an important modulator of blood pressure (BP) in adults homozygous for this polymorphism (TT genotype). The effect of this genetic variant on BP and related central hemodynamic parameters in healthy adults has not been previously investigated and was examined in this study.

METHODOLOGY

Brachial BP, central BP and pulse wave velocity (PWV; SphygmoCor® XCEL) were measured in adults 18-65 years pre-screened for MTHFR genotype. Riboflavin status was assessed using the erythrocyte glutathione reductase activation coefficient (EGRac) assay.

RESULTS

242 adults with the MTHFR 677TT genotype and age-matched non-TT (CC/CT) genotype controls were identified from a total cohort of 2,546 adults pre-screened for MTHFR genotype. The TT genotype was found to be an independent determinant of hypertension (P=0.010), along with low riboflavin status (P=0.002). Brachial systolic and diastolic BP were higher in TT v non-TT adults by 5.5±1.2 mmHg and 2.4±0.9 mmHg, respectively (both P<0.001). A stronger phenotype was observed in females, with an almost 10 mmHg difference in mean systolic BP in TT v non-TT genotype groups: 134.9 (95% CI 132.1-137.6) vs 125.2 (95% CI 122.3-128.0) mmHg; P<0.001. In addition, PWV was faster in women with the TT genotype (P=0.043).

CONCLUSION

This study provides the first evidence that brachial and central BP are significantly higher in adults with the variant MTHFR 677TT genotype, and that the BP phenotype is more pronounced in females. This article is protected by copyright. All rights reserved.

The Association of Circulating Amino Acids and Dietary Inflammatory Potential with Muscle Health in Chinese Community-Dwelling Older People

Amino acids (AAs) and dietary inflammatory potential play essential roles in muscle health. We examined the associations of dietary inflammatory index (DII) of habitual diet with serum AA profile, and ascertained if the associations between DII and muscle outcomes were mediated by serum AAs, in 2994 older Chinese community-dwelling men and women (mean age 72 years) in Hong Kong. Higher serum branched chain AAs (BCAAs), aromatic AAs and total glutathione (tGSH) were generally associated with better muscle status at baseline. A more pro-inflammatory diet, correlating with higher serum total homocysteine and cystathionine, was directly (90.2%) and indirectly (9.8%) through lower tGSH associated with 4-year decline in hand grip strength in men. Higher tGSH was associated with favorable 4-year changes in hand grip strength, gait speed and time needed for 5-time chair stands in men and 4-year change in muscle mass in women. Higher leucine and isoleucine were associated with decreased risk of sarcopenia in men; the associations were abolished after adjustment for BMI. In older men, perturbations in serum sulfur AAs metabolism may be biomarkers of DII related adverse muscle status, while the lower risk of sarcopenia with higher BCAAs may partly be due to preserved BMI.

Osteoprotegerin and MTHFR gene variations in rheumatoid arthritis: association with disease susceptibility and markers of subclinical atherosclerosis

We aimed to explore whether the rs2073618 variant (G1181C) of the osteoprotegerin (OPG) gene and the methylenetetrahydrofolate reductase (MTHFR) rs1801131 (A1298AC) and rs1801133 (C677T) gene polymorphisms contribute to rheumatoid arthritis (RA) susceptibility and RA related subclinical atherosclerosis. Overall 283 RA patients and 595 healthy controls (HC) were genotyped for common variants of the OPG and MTHFR genes using PCR based assays. Clinical and laboratory parameters were recorded following thorough chart review. Surrogate markers of subclinical atherosclerosis (Carotid/Femoral intima media thickness/plaque formation) along with traditional risk factors for atherosclerosis were assessed in all RA patients and 280HC. Increased prevalence of the CC genotype of the rs2073618 variant was detected in RA patients vs HC (42.4% vs. 33%, p-value: 0.04). RA patients with high serum titers of rheumatoid factor (RF) or anti-cyclic citrullinated peptide (CCP) antibodies displayed increased prevalence of the CC genotype of the rs2073618 variant of the OPG gene compared to HC (48.6% and 47.5 vs 33.3%, p-values: 0.0029and 0.0077 respectively). Of interest, this genotype turned to be associated with higher carotid IMT scores (0.872 ± 0.264 vs 0.816 ± 0.284, p-value: 0.01) and marginally with higher rates of carotid plaque formation (66% vs 54.1%, p = 0.06). The MTHFR 1298CC genotype was more prevalent only in the anti-CCP positive group compared to HC, with no associations detected with markers of subclinical atherosclerosis, following adjustment for traditional cardiovascular (CVD) risk factors. Reduced rates of carotid/femoral plaque formation were detected among RA patients harboring the MTHFR TT genotype (52.4 vs 72.7, p-value: 0.009, respectively). This association remained significant following adjustment for classical CVD risk factors (OR [95% CI 0.364 [0.173–0.765], p-value: 0.008). Genetic variations of the osteoprotegerin and MTHFR genes seem to increase susceptibility for seropositive RA and potentially contribute to subclinical atherosclerosis linked to RA. Larger studies are needed to confirm these findings.

Higher fruit and vegetable variety associated with lower risk of cognitive impairment in Chinese community-dwelling older men: a 4-year cohort study

PURPOSE

Few studies have examined the variety in fruit and vegetable (FV) intake with cognitive impairment in older adults. This study examined the associations of variety in fruit, vegetable and combined FV with 4-year incident cognitive impairment in Chinese community-dwelling older adults.

METHODS

Data was derived from a cohort study among Chinese community-dwelling older adults aged ≥ 65 years in Hong Kong. At baseline, a validated food frequency questionnaire was used to assess variety in fruit, vegetable and combined FV. Cognitive impairment was defined as a Community Screening Instrument of Dementia score of < 29.5 points and/or Mini-Mental State Examination score of < 27 points. Adjusted multiple logistic regression was performed to examine the associations. Results are presented as odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Of the 1518 participants [median age: 70 years (IQR 68-74), 32.7% women] included at baseline, 300 men and 111 women were newly identified as cognitively impaired at the 4-year follow-up. In men, higher variety in vegetable (adjusted OR: 0.97, 95% CI 0.95-0.99, p = 0.029) and combined FV (adjusted OR: 0.98, 95% CI 0.96-0.98, p = 0.039) were significantly associated with a lower risk of cognitive impairment. Fruit variety was not associated with cognitive impairment. In women, there were no associations between variety in fruit, vegetable and combined FV with cognitive impairment in the adjusted model.

CONCLUSION

Independent of FV quantity, higher variety in vegetable and combined FV were associated with lower risk of cognitive impairment in Chinese community-dwelling older adults, and these associations were only observed in men.

Endothelial GTPCH (GTP Cyclohydrolase 1) and Tetrahydrobiopterin Regulate Gestational Blood Pressure, Uteroplacental Remodeling, and Fetal Growth

[Figure: see text].

Serum Amino Acids Patterns and 4-Year Sarcopenia Risk in Community-Dwelling Chinese Older Adults

INTRODUCTION

Dietary protein intake and serum amino acids (AAs) are factors controlling the rate of muscle protein synthesis and catabolism. This study examined the association between serum AAs patterns and incident sarcopenia in community-dwelling older adults.

METHODS

Chinese older adults in Hong Kong aged ≥65 years attended a health check at baseline and 4-year follow-up. At baseline, fasting blood was collected to measure 17 serum AAs. Serum AAs patterns were identified using principal component analysis. Dietary protein intake was assessed using a validated food frequency questionnaire. A composite score was computed by summing the principal component score and sex-standardized protein intake. Six composite scores representing each AAs pattern were available for each participant. Sarcopenia was defined using the updated version of the Asian Working Group for Sarcopenia. Crude and adjusted multiple logistic regressions were performed to examine the associations between each of the 6 composite scores and sarcopenia over 4 years. Results are presented as odds ratio (OR) and 95% confidence interval (CI). To address multiple testing, a Bonferroni correction was applied using a corrected significance level of p < 0.008 (α 0.05/6 patterns).

RESULTS

Data of 2,610 participants (mean age 71.6 years, 45.4% men) were available. In men, serum AAs patterns characterized by high branched-chain AAs (BCAAs) (OR 0.77, 95% CI 0.69-0.87, p < 0.001) and tyrosine, tryptophan, and phenylalanine (OR 0.79, 95% CI 0.71-0.89, p < 0.001) were significantly associated with a lower risk of sarcopenia over 4-year follow-up. After adjusting for confounders, the associations were no longer significant. In women, serum AAs patterns characterized by glutamine, glutamic acid, and methionine (OR 1.28, 95% CI 1.11-1.47, p = 0.001) and arginine, taurine, and serine (OR 1.20, 95% CI 1.06-1.35, p = 0.003) were associated with a higher risk of sarcopenia. After adjusting for confounders, serum AAs pattern characterized by high BCAAs (adjusted OR 1.52, 95% CI 1.25-1.86, p < 0.001) and arginine, taurine, and serine (adjusted OR 1.30, 95% CI 1.09-1.56, p = 0.004) were significantly associated with a higher risk of sarcopenia. No association between other AAs patterns with incident sarcopenia was found.

CONCLUSIONS

In community-dwelling Chinese older adults, serum AAs patterns characterized by high BCAAs and nonessential AAs (arginine, taurine, and serine) were associated with a higher risk of sarcopenia in women. Findings may allow identifying new targets for interventions.

Sulfur amino acid restriction, energy metabolism and obesity: a study protocol of an 8-week randomized controlled dietary intervention with whole foods and amino acid supplements

Background

Dietary sulfur amino acid (SAA) restriction is an established animal model for increasing lifespan and improving metabolic health. Data from human studies are limited. In the study outlined in this protocol, we will evaluate if dietary SAA restriction can reduce body weight and improve resting energy expenditure (REE) and parameters related to metabolic health.

Method/design

Men and women (calculated sample size = 60), aged 18–45 years, with body mass index of 27–35 kg/m² will be included in a double-blind 8-week dietary intervention study. The participants will be randomized in a 1:1 manner to a diet with either low or high SAA. Both groups will receive an equal base diet consisting of low-SAA plant-based whole foods and an amino acid supplement free of SAA. Contrasting SAA contents will be achieved using capsules with or without methionine and cysteine (SAA_high, total diet SAA ~ 50–60 mg/kg body weight/day; SAA_low, total diet SAA ~ 15–25 mg/kg body weight/day). The primary outcome is body weight change. Data and material collection will also include body composition (dual X-ray absorptiometry), resting energy expenditure (whole-room indirect calorimetry) and samples of blood, urine, feces and adipose tissue at baseline, at 4 weeks and at study completion. Measures will be taken to promote and monitor diet adherence. Data will be analyzed using linear mixed model regression to account for the repeated measures design and within-subject correlation.

Discussion

The strength of this study is the randomized double-blind design. A limitation is the restrictive nature of the diet which may lead to poor compliance. If this study reveals a beneficial effect of the SAA_low diet on body composition and metabolic health, it opens up for new strategies for prevention and treatment of overweight, obesity and its associated disorders.

Trial registration ClinicalTrials.gov: NCT04701346, Registration date: January 8th, 2021

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02824-3.

Effects of short-term methionine and cysteine restriction and enrichment with polyunsaturated fatty acids on oral glucose tolerance, plasma amino acids, fatty acids, lactate and pyruvate: results from a pilot study

Objective

In this 7-day pilot study we randomized healthy, normal-weight men and women to either a dietary intervention with methionine and cysteine restriction enriched in PUFA (Met/Cys_low + PUFA, n = 7) or with high contents of methionine, cysteine and SFA (Met/Cys_high + SFA, n = 7). The objective was to describe the short-term responses in oral glucose tolerance, amino acid profile, total fatty acid profile, pyruvate and lactate following a Met/Cys_low + PUFA diet vs. Met/Cys_high + SFA.

Results

The diet groups consisted of five women and two men, aged 20–38 years. After the 7-d intervention median pre- and post-oral glucose tolerance test (OGTT) glucose concentrations were 5 mmol/L and 4 mmol/L respectively in the Met/Cys_low + PUFA group. In the Met/Cys_high + SFA group, median pre- and post-OGTT glucose concentrations were 4.8 mmol/L and 4.65 mmol/L after the 7-d intervention. The responses in the amino acid profiles were similar in both groups during the intervention with the exception of serine. Fatty acids decreased from baseline to day 7 in both groups. Plasma lactate and pyruvate were similar for both groups with an increase to day 3 before approaching baseline values at day 7.

Trial registration

ClinicalTrials.gov: NCT02647970, registration date: January 6^th 2016.

Glutathione Serum Levels and Rate of Multimorbidity Development in Older Adults

We aimed to investigate the association between baseline levels of total serum glutathione (tGSH) and rate of chronic disease accumulation over time. The study population (n = 2,596) was derived from a population-based longitudinal study on ≥60-year-olds living in Stockholm. Participants were clinically assessed at baseline, 3- and 6-year follow-ups. Multimorbidity was measured as the number of chronic conditions from a previously built list of 60 diseases. Linear mixed models were applied to analyze the association between baseline tGSH levels and the rate of multimorbidity development over 6 years. We found that at baseline, participants with ≥4 diseases had lower tGSH levels than participants with no chronic conditions (3.3 vs 3.6 µmol/L; p < .001). At follow-up, baseline levels of tGSH were inversely associated with the rate of multimorbidity development (β * time: -0.044, p < .001) after adjusting for age, sex, education, levels of serum creatinine, C-reactive protein, albumin, body mass index, smoking, and time of dropout or death. In conclusion, serum levels of tGSH are inversely associated with multimorbidity development; the association exists above and beyond the link between tGSH and specific chronic conditions. Our findings support the hypothesis that tGSH is a biomarker of multisystem dysregulation that eventually leads to multimorbidity.

Branched-chain amino acid metabolism, insulin sensitivity and liver fat response to exercise training in sedentary dysglycaemic and normoglycaemic men

AIMS/HYPOTHESIS

Obesity and insulin resistance may be associated with elevated plasma concentration of branched-chain amino acids (BCAAs) and impaired BCAA metabolism. However, it is unknown whether the insulin-sensitising effect of long-term exercise can be explained by concomitant change in BCAAs and their metabolism.

METHODS

We included 26 sedentary overweight and normal-weight middle-aged men from the MyoGlu clinical trial, with or without dysglycaemia, for 12 weeks of supervised intensive exercise intervention, including two endurance and two resistance sessions weekly. Insulin sensitivity was measured as the glucose infusion rate (GIR) from a hyperinsulinaemic-euglycaemic clamp. In addition, maximum oxygen uptake, upper and lower body strength and adipose tissue depots (using MRI and spectroscopy) were measured, and subcutaneous white adipose tissue (ScWAT) and skeletal muscle (SkM) biopsies were harvested both before and after the 12 week intervention. In the present study we have measured plasma BCAAs and related metabolites using CG-MS/MS and HPLC-MS/MS, and performed global mRNA-sequencing pathway analysis on ScWAT and SkM.

RESULTS

In MyoGlu, men with dysglycaemia displayed lower GIR, more fat mass and higher liver fat content than normoglycaemic men at baseline, and 12 weeks of exercise increased GIR, improved body composition and reduced liver fat content similarly for both groups. In our current study we observed higher plasma concentrations of BCAAs (14.4%, p = 0.01) and related metabolites, such as 3-hydroxyisobutyrate (19.4%, p = 0.034) in dysglycaemic vs normoglycaemic men at baseline. Baseline plasma BCAA levels correlated negatively to the change in GIR (ρ = -0.41, p = 0.037) and [Formula: see text] (ρ = -0.47, p = 0.015) after 12 weeks of exercise and positively to amounts of intraperitoneal fat (ρ = 0.40, p = 0.044) and liver fat (ρ = 0.58, p = 0.01). However, circulating BCAAs and related metabolites did not respond to 12 weeks of exercise, with the exception of isoleucine, which increased in normoglycaemic men (10 μmol/l, p = 0.01). Pathway analyses of mRNA-sequencing data implied reduced BCAA catabolism in both SkM and ScWAT in men with dysglycaemia compared with men with normoglycaemia at baseline. Gene expression levels related to BCAA metabolism correlated positively with GIR and markers of mitochondrial content in both SkM and ScWAT, and negatively with fat mass generally, and particularly with intraperitoneal fat mass. mRNA-sequencing pathway analysis also implied increased BCAA metabolism after 12 weeks of exercise in both groups and in both tissues, including enhanced expression of the gene encoding branched-chain α-ketoacid dehydrogenase (BCKDH) and reduced expression of the BCKDH phosphatase in both groups and tissues. Gene expression of SLC25A44, which encodes a mitochondrial BCAA transporter, was increased in SkM in both groups, and gene expression of BCKDK, which encodes BCKDH kinase, was reduced in ScWAT in dysglycaemic men. Mediation analyses indicated a pronounced effect of enhanced SkM (~53%, p = 0.022), and a moderate effect of enhanced ScWAT (~18%, p = 0.018) BCAA metabolism on improved insulin sensitivity after 12 weeks of exercise, based on mRNA sequencing. In comparison, plasma concentration of BCAAs did not mediate any effect in this regard.

CONCLUSION/INTERPRETATION

Plasma BCAA concentration was largely unresponsive to long-term exercise and unrelated to exercise-induced insulin sensitivity. On the other hand, the insulin-sensitising effect of long-term exercise in men may be explained by enhanced SkM and, to a lesser degree, also by enhanced ScWAT BCAA catabolism. Graphical abstract.

The effect of folate on ischemia/reperfusion injury in a rat adnexal torsion model

PURPOSE

The ischemia/reperfusion (I/R) injury of ovaries in adnexal torsion may have inadvertent consequences. Many agents have been studied in terms of their ability to prevent reperfusion damage to ovaries in suspected cases. In this study, folic acid, known to have antioxidative properties, was investigated to determine whether it played a role in the prevention of I/R damage in a rat ovarian torsion model.

METHODS

In this experimental study, 40 female adult Wistar-Albino rats were randomly divided into five groups as control, ischemia, I/R, Fol2 (2 mg/kg folic acid), and Fol4 (4 mg/kg folic acid). In the Fol2 and Fol4 groups, folic acid was intraperitonelly administered 30 min before reperfusion. Blood samples were obtained from the tails of each rat at the second hour of reperfusion.

RESULTS

The total oxidant status (TOS), total antioxidant status, cystatin C and folic acid levels of the five groups were investigated. Folic acid in 2 mg/kg dose could moderately increase the serum folic acid concentration (15.75-19.95 ng/ml, p < 0.05), reduce the level of cystatin C (0.18-0.12 μg/L, p < 0.05), and had a tendency to improve the oxidative stress injury (OSI: 76.05-33.06, p > 0.05), although there was no statistical difference in TOS levels (p = 0.07). Folic acid in 4 mg/kg dose, could significantly increase the serum folic acid concentration (15.75-37.65 ng/ml). However, it did not significantly reduce the level of cystatin C (0.18-0.19 μg/L, p > 0.05), and did not improve oxidative stress injury (76.05-130.58, p > 0.05).

CONCLUSION

Folic acid in 2 mg/kg dose might improve the ovarian I/R injury though this was not statistically significant. Further studies are required to reach a definitive conclusion about the protective effect of folic acid in I/R injury.

Exhaustive Exercise and Post-exercise Protein Plus Carbohydrate Supplementation Affect Plasma and Urine Concentrations of Sulfur Amino Acids, the Ratio of Methionine to Homocysteine and Glutathione in Elite Male Cyclists

Plasma and tissue sulfur amino acid (SAA) availability are crucial for intracellular methylation reactions and cellular antioxidant defense, which are important processes during exercise and in recovery. In this randomized, controlled crossover trial among eight elite male cyclists, we explored the effect of exhaustive exercise and post-exercise supplementation with carbohydrates and protein (CHO+PROT) vs. carbohydrates (CHO) on plasma and urine SAAs, a potential new marker of methylation capacity (methionine/total homocysteine ratio [Met/tHcy]) and related metabolites. The purpose of the study was to further explore the role of SAAs in exercise and recovery. Athletes cycled to exhaustion and consumed supplements immediately after and in 30 min intervals for 120 min post-exercise. After ~18 h recovery, performance was tested in a time trial in which the CHO+PROT group cycled 8.5% faster compared to the CHO group (41:53 ± 1:51 vs. 45:26 ± 1:32 min, p < 0.05). Plasma methionine decreased by ~23% during exhaustive exercise. Two h post-exercise, further decline in methionine had occured by ~55% in the CHO group vs. ~33% in the CHO+PROT group (p_group × _time < 0.001). The Met/tHcy ratio decreased by ~33% during exhaustive exercise, and by ~54% in the CHO group vs. ~27% in the CHO+PROT group (p_group × _time < 0.001) post-exercise. Plasma cystathionine increased by ~72% in the CHO group and ~282% in the CHO+PROT group post-exercise (p_group × _time < 0.001). Plasma total cysteine, taurine and total glutathione increased by 12% (p = 0.03), 85% (p < 0.001) and 17% (p = 0.02), respectively during exhaustive exercise. Using publicly available transcriptomic data, we report upregulated transcript levels of skeletal muscle SLC7A5 (log₂ fold-change: 0.45, FDR:1.8^e−07) and MAT2A (log₂ fold-change: 0.38, FDR: 3.4^e−0.7) after acute exercise. Our results show that exercise acutely lowers plasma methionine and the Met/tHcy ratio. This response was attenuated in the CHO+PROT compared to the CHO group in the early recovery phase potentially affecting methylation capacity and contributing to improved recovery.

Plasma Sulfur Amino Acids and Risk of Cerebrovascular Diseases: A Nested Case-Control Study in the EPIC-Norfolk Cohort

BACKGROUND AND PURPOSE

B-vitamin supplements lower circulating concentrations of homocysteine and may reduce stroke incidence. Homocysteine concentrations are associated with the incidence of stroke but other sulfur-containing compounds in the related metabolic pathway have not yet been investigated for an association with incident cerebrovascular diseases.

METHODS

Nested within the EPIC (European Prospective Investigation Into Cancer and Nutrition)-Norfolk cohort, we established a case-control study with 480 incident cases of cerebrovascular diseases and 480 controls matched by age, sex, and year of baseline examination (1993-1997). Using baseline plasma samples, we assayed sulfur-containing compounds including methionine, homocysteine, cystathionine, cysteine, glutathione, and taurine with liquid chromatography-tandem mass spectrometry. We examined the association of concentrations of each of the compounds and the ratio of methionine to homocysteine (representing activity of one-carbon metabolism) with risk of incident cerebrovascular diseases, adjusted for potential confounders.

RESULTS

Plasma methionine and the methionine/homocysteine ratio were inversely associated with risk of cerebrovascular diseases, with odds ratios per 1 SD of 0.83 (95% CI, 0.72-0.96) and 0.82 (95% CI, 0.71-0.95), respectively. The association of methionine remained significant after adjustment for homocysteine. None of the other examined compounds was significantly associated with incident cerebrovascular diseases.

CONCLUSIONS

These findings suggest that greater availability of methionine, an essential amino acid, may play a role in the prevention of cerebrovascular diseases and explain the previously recognized link between elevated homocysteine and stroke. Further research is needed to determine causation and the potential of circulating methionine as a target in cerebrovascular disease prevention.

Association of MTHFR C677T Polymorphism With Antipsychotic-Induced Change of Weight and Metabolism Index

Although antipsychotic medication contributed to the improvement of psychotic symptoms and reduced relapse, it induced weight gain and metabolic syndrome during antipsychotic medication treatment, which was seriously concerning. To investigate the association of methylenetetrahydrofolate reductase (MTHFR) gene C677T (rs1801133) polymorphism with antipsychotic-induced weight gain and metabolism parameter change, we employed 1,868 patients with schizophrenia in this study and randomly allocated them to seven antipsychotic medication treatment groups. All patients received antipsychotics monotherapy and were followed up for 6 weeks. Height, body weight, and metabolic parameters of the patients were measured at baseline and at 2, 4, and 6 weeks after antipsychotic treatment. We genotyped blood DNA from patients for MTHFR C677T polymorphisms and performed quantitative analyses using analysis of variance (ANOVA) and the analysis of covariance (ANCOVA) among three genotype groups. We found a predominant association between MTHFR C677T and body weight mass index (BMI) change after 6-week risperidone treatment. After 6-week treatment of risperidone, the BMI change rate (%) of MTHFR C677 carriers was significantly higher than that of MTHFR TT genotype carriers [CC (2.81 ± 6.77)%, CT (3.79 ± 5.22)%, TT (1.42 ± 3.53)%, F = 4.749, P = 0.009]. Some of the abnormal metabolic parameters were found to be associated with the MTHFR 677T, including higher levels of low-density lipoprotein and waist circumference. Validation was performed in an independent cohort, consisting of 252 patients with schizophrenia treated with three atypical antipsychotic drugs. Overall, the MTHFR C677 was associated with high risk of antipsychotic-induced weight gain and metabolism abnormalities.

Epigenetic factors in atherosclerosis: DNA methylation, folic acid metabolism, and intestinal microbiota

Atherosclerosis is a complex disease, influenced by both genetic and non-genetic factors. The most important epigenetic mechanism in the pathogenesis of atherosclerosis is DNA methylation, which involves modification of the gene without changes in the gene sequence. Nutrients involved in one-carbon metabolism interact to regulate DNA methylation, especially folic acid and B vitamins. Deficiencies in folic acid and other nutrients, such as vitamins B6 and B12, can increase homocysteine levels, induce endothelial dysfunction, and accelerate atherosclerotic pathological processes. Supplemented nutrients can improve DNA methylation status, reduce levels of inflammatory factors, and delay the process of atherosclerosis. In this review, the influence of intestinal flora on folate metabolism and epigenetics is also considered.

Impact of the common MTHFR 677C→T polymorphism on blood pressure in adulthood and role of riboflavin in modifying the genetic risk of hypertension: evidence from the JINGO project

BACKGROUND

Genome-wide and clinical studies have linked the 677C→T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR) with hypertension, whilst limited evidence shows that intervention with riboflavin (i.e. the MTHFR co-factor) can lower blood pressure (BP) in hypertensive patients with the variant MTHFR 677TT genotype. We investigated the impact of this common polymorphism on BP throughout adulthood and hypothesised that riboflavin status would modulate the genetic risk of hypertension.

METHODS

Observational data on 6076 adults of 18-102 years were drawn from the Joint Irish Nutrigenomics Organisation project, comprising the Trinity-Ulster Department of Agriculture (TUDA; volunteer sample) and the National Adult Nutrition Survey (NANS; population-based sample) cohorts. Participants were recruited from the Republic of Ireland and Northern Ireland (UK) in 2008-2012 using standardised methods.

RESULTS

The variant MTHFR 677TT genotype was identified in 12% of adults. From 18 to 70 years, this genotype was associated with an increased risk of hypertension (i.e. systolic BP ≥ 140 and/or a diastolic BP ≥ 90 mmHg): odds ratio (OR) 1.42, 95% confidence interval (CI) 1.07 to 1.90; P = 0.016, after adjustment for antihypertensive drug use and other significant factors, namely, age, male sex, BMI, alcohol and total cholesterol. Low or deficient biomarker status of riboflavin (observed in 30.2% and 30.0% of participants, respectively) exacerbated the genetic risk of hypertension, with a 3-fold increased risk for the TT genotype in combination with deficient riboflavin status (OR 3.00, 95% CI, 1.34-6.68; P = 0.007) relative to the CC genotype combined with normal riboflavin status. Up to 65 years, we observed poorer BP control rates on antihypertensive treatment in participants with the TT genotype (30%) compared to those without this variant, CT (37%) and CC (45%) genotypes (P < 0.027).

CONCLUSIONS

The MTHFR 677TT genotype is associated with higher BP independently of homocysteine and predisposes adults to an increased risk of hypertension and poorer BP control with antihypertensive treatment, whilst better riboflavin status is associated with a reduced genetic risk. Riboflavin intervention may thus offer a personalised approach to prevent the onset of hypertension in adults with the TT genotype; however, this requires confirmation in a randomised trial in non-hypertensive adults.

Folate levels in hepatocellular carcinoma patients with portal vein thrombosis

BACKGROUND

Portal vein thrombosis (PVT) occurs frequently in hepatocellular carcinoma (HCC) and is often diagnosed in the course of a routine patient evaluation and surveillance for liver cancer. The purpose of this study is to investigate the relationship between folate status and portal vein thrombosis.

METHODS

HCC with PVT patients were 78, HCC without PVT were 60 and control subjects were 70 randomly selected. We evaluate serum and red blood cellular folate, homocysteine, alpha fetal protein cholesterol, triglycerides, prothrombin time.

RESULTS

HCC patients with PVT showed lower levels of serum folate, respect HCC patients without PVT, with an average difference of 1.6 nmol/l p < 0.01 (95% CI - 2.54 to - 0.66), red cell folate 33.6 nmol/l p < 0.001 (95% CI - 43.64 to - 23.55) and albumin 0.29 g/dl p < 0.001 (95% CI - 0.42 to - 0.15); PVT patients displayed higher levels of bilirubin 0.53 mg/dl p < 0.001 (95% CI 0.23 to 0.78), INR 0.91 p < 0.001 (95% CI 0.72 to 1.09), γGT 7.9 IU/l (95% CI 4.14 to 11.65) and homocysteine 4.6 μmol/l p < 0.05 (95% CI 0.32 to 8.87) CONCLUSION: The low folate concentration and higher levels of homocysteine are associated with the loss of antithrombotic function, and with a more aggressive course of HCC and with a higher change of complications related to portal vein thrombosis.

DNA methylation of hypertension-related genes and effect of riboflavin supplementation in adults stratified by genotype for the MTHFR C677T polymorphism

BACKGROUND

The interaction between genetic, epigenetic and environmental factors plays an important role in the aetiology of hypertension. GWAS and observational studies link the C677T polymorphism in methylenetetrahydrofolate reductase (MTHFR) with hypertension, while riboflavin, the MTHFR cofactor, has been shown to reduce blood pressure and global DNA methylation in homozygous (TT genotype) individuals. It is currently unclear whether riboflavin modulates DNA methylation of other hypertension-related genes.

OBJECTIVES

To compare DNA methylation of hypertension-related genes in adults stratified by MTHFR genotype and effect of riboflavin intervention in adults with the variant MTHFR 677TT genotype.

METHOD

Pyrosequencing was carried out for hypertension-related genes (ACE, AGTR1, GCK, GNA12, IGF2, MMP9 and NOS3) in blood samples from participants in previous trials (CC, n = 40; TT, n = 40). The effect of intervention with riboflavin (1.6 mg/d for16 weeks) or placebo on DNA methylation was investigated in adults with the variant MTHFR 677TT genotype (n = 80).

RESULTS

Individuals with the MTHFR 677TT v CC genotype had significantly higher average DNA methylation at NOS3 (+1.66%, P = 0.044). In response to riboflavin supplementation in TT individuals, there was an increase in average DNA methylation at IGF2 (+1.09%, P = 0.019) and a decrease at ACE (-0.44%, P = 0.021) in females only. Specific CpG sites were hypomethylated in GNA12 and hypermethylated in AGTR1.

CONCLUSION

This study provides the first RCT evidence that riboflavin alters DNA methylation of hypertension-related genes in adults with the MTHFR 677TT genotype, providing some insight into mechanisms linking hypertension with the genotype-specific response of BP to riboflavin.

Homocysteine Status Modifies the Treatment Effect of Omega-3 Fatty Acids on Cognition in a Randomized Clinical Trial in Mild to Moderate Alzheimer's Disease: The OmegAD Study

BACKGROUND

Trials of supplementation with omega-3 fatty acids (ω3-FAs) in patients with mild cognitive impairment or Alzheimer's disease (AD) have produced inconsistent effects on cognitive decline. There is evidence of an interaction between B vitamin status and ω3-FAs in relation to brain atrophy and cognitive decline.

OBJECTIVE

We investigated whether baseline levels of plasma total homocysteine (tHcy), a marker of B vitamin status, modify the effects of ω3-FAs supplementation on cognitive performance in moderate AD.

METHODS

This post hoc analysis of the OmegAD trial included 171 community-based patients with AD (MMSE≥15): 88 patients received daily doses of 1.7 g docosahexaenoic acid and 0.6 g eicosapentaenoic acid for 6 months. Treatment outcome on cognition was analyzed according to baseline levels of tHcy using a general linear model and ANCOVA.

RESULTS

We found significant interactions between ω3-FA supplementation and tHcy on cognition and clinical stage assessed by MMSE (p = 0.040), global CDR (p = 0.059), and CDRsob (p = 0.023), but not on ADAS-cog (p = 0.649). In patients with tHcy levels <11.7μmol/L, ω3-FA supplementation improved cognitive performance as measured by MMSE (+7.1%, 95% CI: 0.59 to 13.7%, p = 0.033) and clinical status as measured by CDRsob (-22.3%, 95% CI: -5.8 to -38.7%, p = 0.009) compared with placebo.

CONCLUSION

The effect of ω3-FA supplementation on MMSE and CDR appears to be influenced by baseline tHcy, suggesting that adequate B vitamin status is required to obtain beneficial effects of ω3-FA on cognition.

Exercise during pregnancy mitigates the adverse effects of maternal obesity on adult male offspring vascular function and alters one-carbon metabolism

Maternal obesity during pregnancy can adversely affect adult offspring vascular endothelial function. This study examined whether maternal exercise during pregnancy and lactation mitigates the adverse effects of maternal obesity on offspring vascular endothelial function. Female (C57BL/6N) mice were fed from weaning a control diet (10% kcal fat) or western diet (45% kcal fat) to induce excess adiposity (maternal obesity). After 13 weeks, the female mice were bred and maintained on the diets, with and without access to a running wheel (exercise), throughout breeding, pregnancy, and lactation. Offspring were weaned onto the control or western diet and fed for 13 weeks; male offspring were studied. Maternal exercise prevented the adverse effects of maternal obesity on offspring vascular endothelial function. However, this was dependent on offspring diet and the positive effect of maternal exercise was only observed in offspring fed the western diet. This was accompanied by alterations in aorta and liver one-carbon metabolism, suggesting a role for these pathways in the improved endothelial function observed in the offspring. Obesity and exercise had no effect on endothelial function in the dams but did affect aorta and liver one-carbon metabolism, suggesting the phenotype observed in the offspring may be due to obesity and exercise-induced changes in one-carbon metabolism in the dams. Our findings demonstrate that maternal exercise prevented vascular dysfunction in male offspring from obese dams and is associated with alterations in one-carbon metabolism.

Avascular Necrosis of the Humeral Head in a Patient with Methylenetetrahydrofolate Reductase 1 Gene Polymorphism: A Case Report

CASE

Atraumatic avascular necrosis (AVN) of the humeral head is a debilitating condition with an insidious onset and progressively worsening pain. We report a case of a woman who presented with left shoulder pain with a medical history of a rare genetic polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene. Advanced imaging demonstrated focal AVN of her humeral head. Treatment varies based on the stage of the disease, which, in this case, included an ultrasound-guided intra-articular corticosteroid injection and oral methylated supplementation.

CONCLUSION

In patients with no other known risk factors presenting with AVN of the humeral head, MTHFR polymorphism should be strongly considered a possible cause of AVN.

Serum Homocysteine, Folate, and Vitamin B12 Levels in Patients with Systemic Lupus Erythematosus: A Meta-Analysis and Meta-Regression

BACKGROUND

Patients with systemic lupus erythematosus (SLE) have elevated cardiovascular risk. Hyperhomocysteinemia may be one of the contributing factors to this phenomenon. This study therefore aimed to compare the serum homocysteine levels and the levels of folate and vitamin B12, cofactors for homocysteine metabolism, between individuals with and without SLE.

METHODS

A literature search was performed in PubMed, Embase, and the Cochrane library (from inception to March 31, 2019). Studies comparing serum homocysteine, folate or vitamin B₁₂ levels between individuals with and without SLE were selected. Of the 1040 screened studies, 50 studies met the inclusion criteria.

RESULTS

A total of 50 studies involving 4396 patients with SLE were included. Patients with SLE had a significantly higher serum level of homocysteine (standardized mean difference [SMD], 1.134; 95% CI, 0.795-1.474) and lower level of vitamin B₁₂ (SMD, -0.359; 95% CI, -0.638 to -0.080) than controls. The folate level didn't differ markedly between SLE patients and the control group (SMD, -0.276; 95% CI, -0.674-0.123). Subgroup analysis showed consistent results in adult SLE patients. A random effects meta-regression analysis revealed a significantly inverse correlation between the SMD of homocysteine levels and C3 levels (coefficient, -0.0356, 95% CI, -0.054 to -0.0171; P < .001) and C4 levels (coefficient, -0.0876, 95% CI, -0.1407 to -0.0345; P = .0012).

CONCLUSIONS

Serum homocysteine levels were higher and vitamin B₁₂ levels were lower among individuals with SLE than those without SLE. Physicians are encouraged to monitor these parameters and offer timely interventions for patients with SLE.

Association of Homocysteine, Methionine, and MTHFR 677C>T Polymorphism With Rate of Cardiovascular Multimorbidity Development in Older Adults in Sweden

IMPORTANCE

Strong evidence links high total serum homocysteine (tHcy) and low methionine (Met) levels with higher risk of ischemic disease, but other cardiovascular (CV) diseases may also be associated with their pleiotropic effects.

OBJECTIVES

To investigate the association of serum concentrations of tHcy and Met with the rate of CV multimorbidity development in older adults and to explore the role of methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism in this association.

DESIGN, SETTING, AND PARTICIPANTS

The Swedish National Study on Aging and Care in Kungsholmen is a cohort study of randomly selected individuals aged 60 years or older. The present study included data on 1969 individuals with complete information and without CV diseases at baseline, collected from the baseline examination (2001-2004) to the fourth follow-up (2013-2016). Data analysis was conducted from January to May 2019.

EXPOSURES

Concentrations of tHcy and Met were measured from nonfasting venous blood samples. The Met:tHcy ratio was considered a possible indicator of methylation activity. MTHFR status was dichotomized as any T carriers vs noncarriers.

MAIN OUTCOME AND MEASURES

The number of CV diseases at each wave was ascertained based on medical interviews and records, laboratory test results, and drug data. Linear mixed models were used to study the association of baseline tHcy and Met levels and the rate of CV multimorbidity development, adjusting for sociodemographic characteristics, CV risk factors, chronic disease burden, and drug use.

RESULTS

Of 1969 participants, most were women (1261 [64.0%]), with a mean (SD) age of 70.9 (9.8) years; 1703 participants (86.6%) had at least a high school level of education. Baseline measurements of serum tHcy, Met, and the Met:tHcy ratio were associated with the rate of CV disease accumulation (tHcy: β = 0.023 per year; 95% CI, 0.015 to 0.030; P < .001; Met: β = -0.007 per year; 95% CI, -0.013 to -0.001; P = .02; Met:tHcy ratio: β = -0.017 per year; 95% CI, -0.023 to -0.011; P < .001). The association between low Met concentrations and the rate of CV multimorbidity development was restricted to the group with CT/TT alleles of MTHFR (β = 0.023 per year; 95% CI, 0.006 to 0.041; P = .009). Results remained largely significant when individual CV diseases were removed from the total count 1 at a time (eg, ischemic heart disease, tHcy: β = 0.023 per year; 95% CI, 0.013 to 0.027; P < .001; Met: β = -0.006 per year; 95% CI, -0.011 to -0.0003; P = .04; Met:tHcy ratio: β = -0.015 per year; 95% CI, -0.020 to -0.009; P < .001).

CONCLUSIONS AND RELEVANCE

In this study, high tHcy and low Met levels were associated with faster CV multimorbidity development in older age. The interactive association of Met concentrations and MTHFR polymorphism, together with the association found for the Met:tHcy ratio, point toward the relevance of impaired methylation in the pathogenesis of CV aging.

Critical review of nutrition, blood pressure and risk of hypertension through the lifecycle: do B vitamins play a role?

Hypertension is the leading cause of preventable mortality worldwide, contributing to over 9 million deaths per annum, predominantly owing to cardiovascular disease. The association of obesity, physical inactivity and alcohol with elevated blood pressure (BP) is firmly established. Weight loss or other dietary strategies, such as the Dietary Approaches to Stop Hypertension (DASH) diet, have been shown to be effective in lowering BP. Additionally, specific nutrients are recognised to contribute to BP, with higher sodium intake linked with an increased risk of hypertension, while potassium is associated with a reduced risk of hypertension. Of note, emerging evidence has identified a novel role for one-carbon metabolism and the related B vitamins, particularly riboflavin, in BP. Specifically in adults genetically at risk of developing hypertension, owing to the common C677T polymorphism in MTHFR, supplemental riboflavin (co-factor for MTHFR) was shown in randomised trials to lower systolic BP by up to 13 mmHg. A BP response to intervention of this magnitude could have important clinical impacts, given that a reduction in systolic BP of 10 mmHg is estimated to decrease stroke risk by 40%. This review aims to explore the factors contributing to hypertension across the lifecycle and to critically evaluate the evidence supporting a role for nutrition, particularly folate-related B vitamins, in BP and risk of hypertension. In addition, gaps in our current knowledge that warrant future research in this area, will be identified.

Mechanisms of homocysteine-induced damage to the endothelial, medial and adventitial layers of the arterial wall

Homocysteine (Hcy) is a non-protein forming amino acid which is the direct metabolic precursor of methionine. Increased concentration of serum Hcy is considered a risk factor for cardiovascular disease and is specifically linked to various diseases of the vasculature. Serum Hcy is associated with atherosclerosis, hypertension and aneurysms of the aorta in humans, though the precise mechanisms by which Hcy contributes to these conditions remain elusive. Results from clinical trials that successfully lowered serum Hcy without reducing features of vascular disease in cardiovascular patients have cast doubt on whether or not Hcy directly impacts the vasculature. However, studies in animals and in cell culture suggest that Hcy has a vast array of toxic effects on the vasculature, with demonstrated roles in endothelial dysfunction, medial remodeling and adventitial inflammation. It is hypothesized that rather than serum Hcy, tissue-bound Hcy and the incorporation of Hcy into proteins could underlie the toxic effects of Hcy on the vasculature. In this review, we present evidence for Hcy-associated vascular disease in humans, and we critically examine the possible mechanisms by which Hcy specifically impacts the endothelial, medial and adventitial layers of the arterial wall. Deciphering the mechanisms by which Hcy interacts with proteins in the arterial wall will allow for a better understanding of the pathomechanisms of hyperhomocysteinemia and will help to define a better means of prevention at the appropriate window of life.

Methylenetetrahydrofolate Reductase C677T Gene Polymorphism as a Risk Factor for Hypertension in a Rural Population

Hypertension remains a public health burden despite advances in its management. Hence, the search for further risk stratification tools and prevention and new treatment approaches continues. Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is associated with hypertension. Interestingly, riboflavin, as a cofactor of MTHFR, may control blood pressure in patients with mutant MTHFR variants. These double benefits of a risk stratification tool and treatment approach make it interesting. Because this polymorphism depends on ethnicity and geographic region, we aimed to determine the association between MTHFR C677T gene polymorphism and hypertension in a rural Indonesian-Sundanese population. This population-based case-control study included 213 hypertensive subjects and 202 nonhypertensive subjects as controls. The TaqMan assay was used to determine the MTHFR C677T genotypes. The odds ratio (OR) with 95% confidence interval (CI) was used to assess the risk of association. There was a significant difference in MTHFR C677T allele frequencies between the hypertensive and control groups (62.9% CC, 34.3% CT, 2.8% TT vs. 77.7% CC, 20.8% CT, 1.5% TT; p=0.004) and between mutant (TT and CT) and wild-type genotypes (CC) (p=0.001). The mutant genotype was associated with a risk of hypertension (OR 2.1; 95% CI 1.3-3.5) when adjusted for age, body mass index, waist circumference, and diabetes mellitus. The mutant of the MTHFR C677T gene increases the risk of hypertension in rural Indonesian-Sundanese population. These findings may be used in future studies to evaluate the effect of riboflavin supplementation in this population.

Evidence of a Role for One-Carbon Metabolism in Blood Pressure: Can B Vitamin Intervention Address the Genetic Risk of Hypertension Owing to a Common Folate Polymorphism?

Hypertension in adulthood is recognized as the leading risk factor contributing to mortality worldwide, primarily from cardiovascular disease, whereas hypertension in pregnancy leads to serious adverse fetal and maternal outcomes. This article explores the under-recognized role of one-carbon metabolism in blood pressure (BP) and the potential for folate-related B vitamins to protect against hypertension. Genome-wide association studies and clinical studies provide evidence linking the 677C→T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR) with BP and increased risk of hypertension and hypertension in pregnancy. A novel role for riboflavin (the MTHFR cofactor) has recently emerged, however, with evidence from randomized trials that supplemental riboflavin can lower BP specifically in adults with the variant MTHFR 677TT genotype. Further studies are required to elucidate the biological mechanisms linking one-carbon metabolism with BP and explore the effect of riboflavin in modulating the genetic risk of hypertension in early and later life.

Circulating amino acids are associated with bone mineral density decline and ten-year major osteoporotic fracture risk in older community-dwelling adults

With aging, poor bone mineral density (BMD) and accelerated decrease in BMD are strong risk factors for fracture. Reports of the associations of dietary protein intake with bone strength are inconsistent, possibly owing to differences in protein sources and amino acid (AA) composition. We examined the associations of serum AA with 4-year hip BMD loss and subsequent fracture risk within 10 years in older community-dwelling adults, and further addressed whether lifestyle, dietary protein intake and its source, and body composition would affect the associations. In 1424 men and 1573 women (mean age 72 years), using binary logistic regression, higher serum valine, leucine, isoleucine and tryptophan concentrations were associated (or approaching a borderline significance in case of the last three ones) with less hip BMD decline (defined as BMD loss ≥ 2.8 times the precision error of the BMD measurement at femoral neck) in 4 years later, with the OR (95%CI) /SD of AA increase, ranging from 0.83 (0.75, 0.91) to 0.92 (0.87, 0.98) after multiple adjustments for baseline age, gender, BMI, BMD, estimated glomerular filtration rate (eGFR), dietary protein intake (animal- and plant-derived protein intakes), calcium intake, established lifestyles (physical activity level, smoking and alcohol drinking status), osteoporosis medications, and changes of body fat and lean muscle mass. Higher serum total homocysteine (tHcy) concentration was independently associated with BMD decline 4 years later (OR (95%CI) /SD of 1.16 (1.05, 1.27)). Using multivariate Cox regression, higher serum tryptophan concentration potentially predicted low risk of incident major osteoporotic fractures (MOFs) (HR/SD (95%CI)=0.86 (0.75, 0.98)) after multiple adjustments. Higher serum tHcy was associated with MOFs (HR/SD (95%CI)=1.29 (1.12, 1.50)) risk after multiple adjustments in men. These findings suggest that a specific AA profile correlates with greater BMD and lower subsequent fracture risk, independent of diet and lifestyle factors.

Association of Methionine to Homocysteine Status With Brain Magnetic Resonance Imaging Measures and Risk of Dementia

IMPORTANCE

Impairment of methylation status (ie, methionine to homocysteine ratio) may be a modifiable risk factor for structural brain changes and incident dementia.

OBJECTIVE

To investigate the association of serum markers of methylation status and sulfur amino acids with risk of incident dementia, Alzheimer disease (AD), and the rate of total brain tissue volume loss during 6 years.

DESIGN, SETTING, AND PARTICIPANTS

This population-based longitudinal study was performed from March 21, 2001, to October 10, 2010, in a sample of 2570 individuals aged 60 to 102 years from the Swedish Study on Aging and Care in Kungsholmen who were dementia free at baseline and underwent comprehensive examinations and structural brain magnetic resonance imaging (MRI) on 2 to 3 occasions during 6 years. Data analysis was performed from March 1, 2018, to October 1, 2018.

MAIN OUTCOMES AND MEASURES

Incident dementia, AD, and the rate of total brain volume loss.

RESULTS

This study included 2570 individuals (mean [SD] age, 73.1 [10.4] years; 1331 [56.5%] female). The methionine to homocysteine ratio was higher in individuals who consumed vitamin supplements (median, 1.9; interquartile range [IQR], 1.5-2.6) compared with those who did not (median, 1.8; IQR, 1.3-2.3; P < .001) and increased per each quartile increase of vitamin B12 or folate. In the multiadjusted model, an elevated baseline serum total homocysteine level was associated with an increased risk of dementia and AD during 6 years: for the highest homocysteine quartile compared with the lowest, the hazard ratios (HRs) were 1.60 (95% CI, 1.01-2.55) for dementia and 2.33 (95% CI, 1.26-4.30) for AD. In contrast, elevated concentrations of methionine were associated with a decreased risk of dementia (HR, 0.54; 95% CI, 0.36-0.81) for the highest quartile compared with the lowest. Higher values of the methionine to homocysteine ratio were significantly associated with lower risk of dementia and AD: for the fourth methionine-homocysteine quartile compared with the first quartile, the HR was 0.44 (95% CI, 0.27-0.71) for incident dementia and 0.43 (95% CI, 0.23-0.80) for AD. In the multiadjusted linear mixed models, a higher methionine to homocysteine ratio was associated with a decreased rate of total brain tissue volume loss during the study period (β [SE] per 1-SD increase, 0.038 [0.014]; P = .007).

CONCLUSIONS AND RELEVANCE

The methionine to homocysteine status was associated with dementia development and structural brain changes during the 6-year study period, suggesting that a higher methionine to homocysteine ratio may be important in reducing the rate of brain atrophy and decreasing the risk of dementia in older adults.

Plasma Sulphur-Containing Amino Acids, Physical Exercise and Insulin Sensitivity in Overweight Dysglycemic and Normal Weight Normoglycemic Men

Plasma sulphur-containing amino acids and related metabolites are associated with insulin sensitivity, although the mechanisms are unclear. We examined the effect of exercise on this relationship. Dysglycemic (n = 13) and normoglycemic (n = 13) men underwent 45 min cycling before and after 12 weeks exercise intervention. We performed hyperinsulinemic euglycemic clamp, mRNA-sequencing of skeletal muscle and adipose tissue biopsies, and targeted profiling of plasma metabolites by LC-MS/MS. Insulin sensitivity increased similarly in dysglycemic and normoglycemic men after 12 weeks of exercise, in parallel to similar increases in concentration of plasma glutamine, and decreased concentrations of plasma glutamate, cysteine, taurine, and glutathione. Change in plasma concentrations of cysteine and glutathione exhibited the strongest correlations to exercise-improved insulin sensitivity, and expression of a cluster of genes essential for oxidative phosphorylation and fatty acid metabolism in both skeletal muscle and adipose tissue, as well as mitochondria-related genes such as mitofilin. Forty-five min of cycling decreased plasma concentrations of glutamine and methionine, and increased plasma concentrations of glutamate, homocysteine, cystathionine, cysteine, glutathione, and taurine. Similar acute responses were seen in both groups before and after the 12 weeks training period. Both acute and long-term exercise may influence transsulphuration and glutathione biosynthesis, linking exercise-improved insulin sensitivity to oxidative stress and mitochondrial function.

Protein intake in the early recovery period after exhaustive exercise improves performance the following day

The aim of the present study was to investigate the effect of protein and carbohydrate ingestion during early recovery from exhaustive exercise on performance after 18-h recovery. Eight elite cyclists (V̇o2max: 74.0 ± 1.6 ml·kg−1·min−1) completed two exercise and diet interventions in a double-blinded, randomized, crossover design. Participants cycled first at 73% of V̇o2max (W73%) followed by 1-min intervals at 90% of V̇o2max until exhaustion. During the first 2 h of recovery, participants ingested either 1.2 g carbohydrate·kg−1·h−1 (CHO) or 0.8 g carbohydrate + 0.4 g protein·kg−1·h−1 (CHO + PROT). The diet during the remaining recovery period was similar for both interventions and adjusted to body weight. After an 18-h recovery, cycling performance was assessed with a 10-s sprint test, 30 min of cycling at W73%, and a cycling time trial (TT). The TT was 8.5% faster (41:53 ± 1:51 vs. 45:26 ± 1:32 min; P < 0.03) after CHO + PROT compared with CHO. Mean power output during the sprints was 3.7% higher in CHO + PROT compared with CHO (1,063 ± 54 vs. 1,026 ± 53 W; P = 0.01). Nitrogen balance in the recovery period was negative in CHO and neutral in CHO + PROT (−82.4 ± 11.5 vs. 7.0 ± 15.4 mg/kg; P < 0.01). In conclusion, TT and sprint performances were improved 18 h after exhaustive cycling by CHO + PROT supplementation during the first 2 h of recovery compared with isoenergetic CHO supplementation. Our results indicate that intake of carbohydrate plus protein after exhaustive endurance exercise more rapidly converts the body from a catabolic to an anabolic state than carbohydrate alone, thus speeding recovery and improving subsequent cycling performance.

NEW & NOTEWORTHY Prolonged high intensity endurance exercise depends on glycogen utilization and high oxidative capacity. Still, exhaustion develops and effective recovery strategies are required to compete in multiday stage races. We show that coingestion of protein and carbohydrate during the first 2 h of recovery is superior to isoenergetic intake of carbohydrate to stimulate recovery, and improves both endurance time-trial and 10-s sprint performance the following day in elite cyclists.

Combining Dietary Sulfur Amino Acid Restriction with Polyunsaturated Fatty Acid Intake in Humans: A Randomized Controlled Pilot Trial

Dietary and plasma total cysteine (tCys) have been associated with adiposity, possibly through interaction with stearoyl–CoA desaturase (SCD), which is an enzyme that is involved in fatty acid and energy metabolism. We evaluated the effect of a dietary intervention with low cysteine and methionine and high polyunsaturated fatty acids (PUFAs) on plasma and urinary sulfur amino acids and SCD activity indices. Fourteen normal-weight healthy subjects were randomized to a seven-day diet low in cysteine and methionine and high in PUFAs (Cys/Met_low + PUFA), or high in saturated fatty acids (SFA), cysteine, and methionine (Cys/Met_high + SFA). Compared with the Cys/Met_high + SFA group, plasma methionine and cystathionine decreased (p-values < 0.05), whereas cystine tended to increase (p = 0.06) in the Cys/Met_low + PUFA group. Plasma total cysteine (tCys) was not significantly different between the groups. Urinary cysteine and taurine decreased in the Cys/Met_low + PUFA group compared with the Cys/Met_high + SFA group (p-values < 0.05). Plasma SCD-activity indices were not different between the groups, but the change in cystine correlated with the SCD-16 index in the Cys/Met_low + PUFA group. A diet low in methionine and cysteine decreased plasma methionine and urinary cysteine and taurine. Plasma tCys was unchanged, suggesting that compensatory mechanisms are activated during methionine and cysteine restriction to maintain plasma tCys.

Food Overconsumption in Healthy Adults Triggers Early and Sustained Increases in Serum Branched-Chain Amino Acids and Changes in Cysteine Linked to Fat Gain

Background

Plasma concentrations of branched-chain amino acids (BCAAs) and the sulfur-containing amino acid cysteine are associated with obesity and insulin resistance. BCAAs predict future diabetes.

Objective

We investigated amino acid changes during food overconsumption.

Methods

Forty healthy men and women with a body mass index (mean ± SEM) of 25.6 ± 0.6 were overfed by 1250 kcal/d for 28 d, increasing consumption of all macronutrients. Insulin sensitivity and body composition were assessed at baseline (day 0) and day 28. Fasting serum amino acids were measured at days 0, 3, and 28. Linear mixed-effects models evaluated the effect of time in the total group and separately in those with low and high body fat gain (below compared with at or above median fat gain, 1.95 kg). At days 0 and 28, insulin-induced suppression of serum amino acids during a hyperinsulinemic-euglycemic clamp test and, in a subset (n = 20), adipose tissue mRNA expression of selected amino acid metabolizing enzymes were assessed.

Results

Weight increased by 2.8 kg. High fat gainers gained 2.6 kg fat mass compared with 1.1 kg in low fat gainers. Valine and isoleucine increased at day 3 (+17% and +22%, respectively; P ≤ 0.002) and remained elevated at day 28, despite a decline in valine (P = 0.019) from day 3 values. Methionine, cystathionine, and taurine were unaffected. Serum total cysteine (tCys) transiently increased at day 3 (+11%; P = 0.022) only in high fat gainers (P-interaction = 0.043), in whom the cysteine catabolic enzyme cysteine dioxygenase (CDO1) was induced (+26%; P = 0.025) in adipose tissue (P-interaction = 0.045). Overconsumption did not alter adipose tissue mRNA expression of the BCAA-metabolizing enzymes branched-chain keto acid dehydrogenase E1α polypeptide (BCKDHA) or branched-chain amino transferase 1 (BCAT1). In the total population at day 0, insulin infusion decreased all serum amino acids (-11% to -47%; P < 0.01), except for homocysteine and tCys, which were unchanged, and glutathione, which was increased by 54%. At day 28, insulin increased tCys (+8%), and the insulin-induced suppression of taurine and phenylalanine observed at day 0, but not that of BCAAs, was significantly impaired.

Conclusions

These findings highlight the role of nutrient oversupply in increasing fasting BCAA concentrations in healthy adults. The link between cysteine availability, CDO1 expression, and fat gain deserves investigation. This trial was registered at www.clinicaltrials.gov as NCT00562393.

Effects Of Endothelin-1 On Intracellular Tetrahydrobiopterin Levels In Vascular Tissue

OBJECTIVE

Tetrahydrobiopterin (BH4) is the essential cofactor of endothelial nitric oxide synthase (eNOS) and intracellular levels of BH4 is regulated by oxidative stress. The aim of this paper was to describe the influence of exogenous endothelin-1 on intracellular BH4 and its oxidation products dihydrobiopterin (BH2) and biopterin (B) in a wide range of vascular tissue.

DESIGN

Segments of internal mammary artery (IMA) and human saphenous vein (SV) from 41 patients undergoing elective surgery were incubated in ET-1 (0.1 μM). Aorta and lung from transgenic mice overexpressing ET-1 in the endothelium (ET-TG) were analysed with regards to intracellular biopterin levels. Human umbilical vein endothelial cells (HUVEC) were incubated in ET-1 (0.1 μM) and intracellular biopterin levels were analysed. From 6 healthy women undergoing caesarean section, subcutaneous fat was harvested and the resistance arteries in these biopsies were tested for ET-mediated endothelial dysfunction.

RESULTS

In HUVEC, exogenous ET-1 (0.1 μM) did not significantly change intracellular BH4, 1.54 ± 1.7 vs 1.68 ± 1.8 pmol/mg protein; p = .8. In IMA and SV, exogenous ET-1(0.1 μM) did not change intracellular BH4 n = 10, p = .4. In aorta from wild type vs ET-TG mice there was no significant difference in intracellular BH4 between the groups: 1.3 ± 0.49 vs 1.23 ± 0.3 pmol/mg protein; p = .6. In resistance arteries (n = 6) BH4 together with DTE (an antioxidant) was not able to prevent ET-mediated endothelial dysfunction.

CONCLUSION

ET-1 did not significantly alter intracellular tetrahydrobiopterin levels in IMA, SV, HUVEC or aorta from ET-TG mice. These findings are important for future research in ET-1 mediated superoxide production and endothelial dysfunction.

Contribution of MTHFR gene variants in lupus related subclinical atherosclerosis

OBJECTIVE

Elevated concentrations of homocysteine have been previously identified as an independent risk factor for subclinical atherosclerosis in patients with systemic lupus erythematosus (SLE). Given that heightened homocysteine levels are known to be strongly influenced by genetic factors, in the current study we investigated the contribution of high homocysteine levels as well as of functional polymorphisms of the gene encoding for the enzyme 5, 10- methylenetetrahydrofolate reductase (MTHFR) to atherosclerotic disease characterizing SLE patients.

METHODS

Peripheral DNA samples from 150 SLE patients, 214 rheumatoid arthritis (RA) patients and 561 age/sex matched apparently healthy volunteers (HC) were genotyped by PCR-based assays for the detection of the MTHFR gene polymorphisms (c. 677C > T and c. 1298A > C). All SLE patients and 30 age sex matched RA patients underwent assessment for subclinical atherosclerosis [ultrasound measurement of intima-media thickness scores (IMT) and detection of carotid and/or femoral (C/F) plaque] and complete clinical and laboratory evaluation including serum homocysteine levels. Data were analyzed using univariate and multivariate models (SPSS 21.0).

RESULTS

Hyperhomocysteinemia was detected in 26.0% of SLE patients compared to 6.7% of age/sex matched RA controls (p = 0.02). Higher serum B12 levels and decreased frequency of the MTHFR 677TT variant in RA patients could potentially account for the observed differences between the groups. In SLE patients, both hyperhomocysteinemia and MTHFR 677TT genotype were identified as independent contributors for plaque formation, following adjustment for traditional cardiovascular risk factors and disease related features, including age, sex, BMI, cholesterol and triglyceride levels, presence of arterial hypertension, smoking (pack/years), disease duration and total steroid dose [OR 95% (CI): 5.8 (1.0-35.8) and 5.2 (1.1-24.0), respectively]. MTHFR 677TT genotype, but not hyperhomocysteinemia was also found to confer increased risk for arterial wall thickening, after the above confounders were taken into account [OR (95%) CI: 4.9 (1.2-20.6)].

CONCLUSIONS

Hyperhomocysteinemia and MTHFR 677TT genetic variant emerged as independent risk factors for subclinical atherosclerosis in SLE patients, implying genetic influences as potential contributors to the increased burden of atherosclerotic disease characterizing SLE.