Search Results (188)

Background/Objectives: Low folate intake before and during pregnancy increases the risk of neural tube defects and other adverse outcomes. Gene variants such as MTHFR 677C>T (rs1801133) may increase risks associated with suboptimal folate intake. Our objective was to use BALB/cJ Mthfr^677C>T mice to evaluate the effects of the TT genotype and low folate diets on embryonic development and MTHFR protein expression in pregnant mice. Methods: Female 677CC (mCC) and 677TT (mTT) mice were fed control (2 mg folic acid/kg (2D)), 1 mg folic acid/kg (1D) and 0.3 mg folic acid/kg (0.3D) diets before and during pregnancy. Embryos and maternal tissues were collected at embryonic day 10.5. Embryos were examined for developmental delays and defects. Methyltetrahydrofolate (methylTHF) and total homocysteine (tHcy) were measured in maternal plasma, and MTHFR protein expression was evaluated in maternal liver. Results: MethylTHF decreased due to the experimental diets and mTT genotype. tHcy increased due to 0.3D and mTT genotype; mTT 0.3D mice had significantly higher tHcy than the other groups. MTHFR expression was lower in mTT liver than mCC. MTHFR protein expression increased due to low folate diets in mCC mice, whereas in mTT mice, MTHFR expression increased only due to 1D. Developmental delays were increased in the litters of mTT mice fed 1D and 0.3D. Conclusions: The Mthfr^677C>T mouse models the effects of the MTHFR 677TT genotype in humans and provides a folate-responsive model for examination of the effects of folate intake and the MTHFR 677C>T variant during gestation. Full article

Methyl groups can be obtained either from the diet (labile methyl groups) or produced endogenously (methylneogenesis) via one-carbon (C1-) metabolism as S-adenosylmethionine (SAM). The essential nutrients folate and choline (through betaine) are metabolically entwined to feed their methyl groups into C1-metabolism. A choline-deficient diet in rats produces a 31–40% reduction in liver folate content, 50% lower hepatic SAM levels, and a doubling of plasma homocysteine. Similarly, folate deficiency results in decreased total hepatic choline. Thus, sufficient intakes of both folate and choline (or betaine) contribute to safeguarding the methyl balance in the body. A significant amount of choline (as phosphatidylcholine) is produced in the liver via the SAM-dependent phosphatidylethanolamine methyltransferase. Experimental studies using diets deficient in several methyl donors have shown that supplemental betaine was able to rescue not only plasma betaine but also plasma folate. Fasting plasma homocysteine concentrations are mainly determined by folate intake or status, while the effect of choline or betaine on fasting plasma homocysteine is minor. This appears to contradict the finding that approximately 50% of cellular SAM is provided via the betaine-homocysteine methyltransferase (BHMT) pathway, which uses dietary choline (after oxidation to betaine) or betaine to convert homocysteine to methionine and then to SAM. However, it has been shown that the relative contribution of choline and betaine to cellular methylation is better reflected by measuring plasma homocysteine after a methionine load test. Choline or betaine supplementation significantly lowers post-methionine load homocysteine, whereas folate supplementation has a minor effect on post-methionine load homocysteine concentrations. This review highlights the interactions between folate and choline and the essentiality of choline as a key player in C1-metabolism. We further address some areas of interest for future work. Full article

Pre-eclampsia (PE) is a hypertensive pregnancy complication. Oxidative stress is hypothesized to contribute to the pathophysiology of PE. Both the hydrogen sulfide (H₂S) and oxytocin (OT) systems might play a role in the pathophysiology of PE, like their antioxidant and hypotensive effects. Thus, the role of the interaction of the OT and H₂S systems in the context of PE was further elucidated in the present clinical case–control study “NU-HOPE” (Nürnberg-Ulm: The role of H₂S and Oxytocin Receptor in Pre-Eclampsia; ethical approval by the Landesärztekammer Bayern, file number 19033, 29 August 2019), comparing uncomplicated pregnancies, early onset PE (ePE, onset < 34 weeks gestational age) and late onset PE (lPE, onset > 34 weeks gestational age). Routine clinical data, serum H₂S and homocysteine levels, and tissue protein expression, as well as nitrotyrosine formation, were determined. The main findings were (i) unchanged plasma sulfide levels, (ii) significantly elevated homocysteine levels in ePE, but not lPE, (iii) significantly elevated expression of H₂S enzymes and OT receptor in the placenta in lPE, and (iv) significantly elevated nitrotyrosine formation in the lPE myometrium. Taken together, these findings suggest a role for the interaction of the endogenous H₂S- and OT/OTR systems in the pathophysiology of pre-eclampsia, possibly linked to impaired antioxidant protection. Full article

Homocysteine (Hcy) is becoming a well-established risk factor for cardiovascular disease (CVD), mainly involving endothelial dysfunction and atherogenesis. Endothelial dysfunction is reflected primarily in the complex regulation of the main physiological and pathophysiological processes. There is increasing evidence regarding abnormally high concentrations of plasma total homocysteine, or plasma hyperhomocysteinemia, contributing to endothelial dysfunction, inflammation, and CVD. This clinical and experimental study examined the connection between Hcy and cardiovascular disease risk. Homocysteine is a marker of total vascular damage that must be monitored and controlled as early as possible. Dietary and lifestyle changes are recommended for most patients with hyperhomocysteinemia (Hhcy). The purpose of this paper is to review the data from the specialized literature that demonstrate that there is a direct link between endothelial injury and increased homocysteine levels, identifying existing evidence, describing new mechanisms, and exploring potential new therapeutic options. These aspects continue to be debated, and additional efforts are required to refine therapeutic strategies and to investigate the potential implications of Hcy in health and disease. Full article

Purpose: Homocysteine (HCY) metabolism is regulated by the methionine cycle, which is essential for DNA methylation and is associated with the folate cycle. This study examines the alterations in DNA methylation signature including epigenetic age changes, measure cell-free DNA (cfDNA), and HCY concentrations, and identifies genetic markers that may influence homocysteine response following folic acid (FA) supplementation in individuals with hyperhomocysteinemia (HHC). Methods: Blood samples were obtained from 43 HHC patients undergoing FA supplementation. We quantified FA and HCY levels, separated plasma and white blood cell fractions, and evaluated global DNA methylation using LINE-1 bisulfite pyrosequencing. Biological age was determined using Illumina BeadArray technology, and whole-exome sequencing was performed to investigate the patients’ genetic backgrounds. Results: Following FA supplementation, cfDNA levels significantly decreased and correlated positively with HCY (r = 0.2375). Elevated average LINE-1 methylation of cfDNA and PBMC-origin DNA was observed, with mean relative changes of 1.9% for both sample types. Regarding HCY levels, we categorized patients based on their response to FA supplementation. FA responders showed decreased HCY from 15.7 ± 5.5 to 11 ± 2.9 µmol/L, while in FA non-responders, an opposite trend was detected. The average biological age was reduced by 2.6 years, with a notable reduction observed in 80% of non-responders and 48% of responders. Sequencing identified mutations in several genes related to the one-carbon cycle, including MTRR, CHAT, and MTHFD1, with strong correlations to the non-responder phenotypes found in genes like PRMT3, TYMS, DNMT3A, and HIF3A. Conclusions: FA supplementation influences the HCY level, as well as affects the cfDNA amount and the DNA methylation pattern. However, genetic factors may play a crucial role in mediating individual responses to folate intake, emphasizing the need for personalized approaches in managing hyperhomocysteinemia. Full article

Background/Objectives: Low vitamin D status seems to be associated with increased cardiometabolic risk, and was found to attenuate cardiometabolic benefits of statins in men. The aim of the current study was to investigate whether a different vitamin D status determines the pleiotropic effects of statins in women. Methods: This pilot, single-center, prospective, matched-cohort study included 78 women with hypercholesterolemia requiring statin therapy, assigned into one of three age-, plasma lipid-, and body mass index-matched groups: women with vitamin D deficiency (group I), women with vitamin D insufficiency (group II), and women with normal vitamin D homeostasis (group III). Throughout the study (16 weeks), all patients were treated with atorvastatin. The outcome of interest included plasma lipids, glucose homeostasis markers (fasting glucose, HOMA-IR and glycated hemoglobin), plasma levels of 25-hydroxyvitamin D, creatine kinase, uric acid, high-sensitivity C-reactive protein, homocysteine, fibrinogen, urinary albumin-to-creatinine ratio (UACR), and computed values of a 10-year risk of atherosclerotic events. Results: Compared to the control group (group III), group I was characterized by higher values of HOMA-IR, glycated hemoglobin, uric acid, hsCRP, homocysteine, fibrinogen, a UACR, and a 10-year risk of atherosclerotic events, whereas group II had higher values of hsCRP, homocysteine and a UACR. Atorvastatin reduced plasma levels of total and LDL cholesterol and a 10-year risk of atherosclerotic events in all study groups, but this effect was weakest in group I and strongest in group III. In group III, the drug decreased uric acid, hsCRP, homocysteine, fibrinogen, and the UACR. In the remaining groups, its effect was limited to a small decrease in only hsCRP (group I) or in hsCRP and homocysteine (group II). In group I, atorvastatin treatment was associated with an increase in HOMA-IR, glycated hemoglobin, and creatine kinase. Conclusions: Low vitamin D status may exert an unfavorable effect on the lipid-dependent and lipid-independent effects of atorvastatin in middle-aged or elderly women. Full article

Background/Objectives: Arterial stiffness is a prevalent age-related condition that can significantly increase the risk of cardiovascular disease and mortality in older adults. Understanding the factors that contribute to vascular health, including metabolic dysfunction and hyperhomocysteinemia, alongside vitamin B status, is essential for developing effective interventions. This study aimed to explore the relationship between plasma levels of homocysteine, folate, and vitamin B12, as well as various indices of metabolic dysfunction, in elderly individuals with arterial stiffness. Methods: We conducted a cross-sectional analysis involving 884 participants aged 65 and older, assessing arterial stiffness using the cardio/ankle vascular index method. Additionally, we collected fasting blood samples to evaluate plasma homocysteine, folate, vitamin B12 levels, and other relevant biochemical markers. Results: Higher plasma homocysteine levels are significantly correlated with elevated CAVI scores and increased indices of metabolic dysfunction (p < 0.05). Furthermore, a multivariate logistic regression analysis demonstrated that elevated plasma homocysteine levels, along with higher levels of lipid accumulation product (LAP), triglyceride/glucose index (TyG), and visceral adiposity index (VAI), are associated with increased arterial stiffness. Conclusions: These findings suggest that monitoring and optimizing homocysteine, folate, and vitamin B12 levels may be beneficial for preventing or managing arterial stiffness and related metabolic disorders in the elderly population. Full article

Homocysteine, a sulfur-containing amino acid, is an intermediate product during the metabolism of methionine, a vital amino acid. An elevated concentration of homocysteine in the plasma, named hyperhomocysteinemia, has been significantly related to the onset of several diseases, including diabetes, multiple sclerosis, osteoporosis, cancer, and neurodegenerative disorders such as dementia, Alzheimer’s and Parkinson’s diseases. An interaction between metabolic pathways of homocysteine and gut microbiota has been reported, and specific microbial signatures have been found in individuals experiencing hyperhomocysteinemia. Furthermore, some evidence suggests that gut microbial modulation may exert an influence on homocysteine levels and related disease progression. Conventional approaches for managing hyperhomocysteinemia typically involve dietary interventions alongside the administration of supplements such as B vitamins and betaine. The present review aims to synthesize recent advancements in understanding interventions targeted at mitigating hyperhomocysteinemia, with a particular emphasis on the role of gut microbiota in these strategies. The emerging therapeutic potential of gut microbiota has been reported for several diseases. Indeed, a better understanding of the complex interaction between microbial species and homocysteine metabolism may help in finding novel therapeutic strategies to counteract hyperhomocysteinemia. Full article

Background: Homocystinuria caused by cystathionine β-synthase (CBS) deficiency is the most common congenital disorder related to sulfur amino acid metabolism, manifested by neurological, vascular, and connective tissue involvement. Methods: This study analyzed the pathogenic gene and molecular mechanism of two classic homocystinuria families through whole exome sequencing and in vitro experiments including minigene assay and expression analysis. Results: Both probands presented with ectopia lentis, high myopia, and abnormally elevated homocysteine level, but one of them had more severe clinical manifestations, including general growth retardation, mild intellectual disability, and severe pectus excavatum. Their family members were phenotypically normal but presented slightly higher levels of homocysteine in plasma. Whole exome sequencing revealed that the two probands carried c.833T>C (p.Ile278Thr) and c.1359-1G>C, and c.919G>A (p.Gly307Ser) and c.131delT (p.Tle44Thrfs*38) compound heterozygous mutations in the CBS gene, respectively. Bioinformatics and in vitro functional analysis showed that the c.1359-1G>C mutation affects the normal splicing of CBS gene, resulting in the production of two abnormal transcripts and the production of two truncated proteins. One of the c.1359-1G>C splicing events (c.1359_1467del) and c.131delT (p.Tle44Thrfs*38) both lead to a significant decrease in CBS mRNA and protein levels. Conclusions: Accurate diagnosis of patients with homocystinuria is of great importance for timely and effective treatment, as well as for the provision of appropriate genetic counseling and prenatal diagnosis guidance to the affected families. Full article

Homocysteine is an amino acid derived from methionine which is metabolized via vitamin B₆ (pyridoxine)- and vitamin B₁₂ (cobalamin)-dependent pathways. Supplementation of B vitamins has been shown to effectively reduce plasma homocysteine levels. Previous research has also demonstrated an association between lower plasma homocysteine levels and decreased risk of myocardial infarction, stroke, and venous thromboembolism. However, whether supplementation of B vitamins is associated with risk reduction in thromboembolic events and confers clinical benefits remains inconclusive. This review examines clinical trials published over the past 29 years to assess the effects of B vitamin supplementation on thrombotic risk reduction and homocysteine metabolism. The findings from these studies are inconsistent, and the impact of B vitamins on thrombosis prevention remains uncertain. Given the conflicting evidence, further clinical and translational research is necessary to clarify the role of B vitamin supplementation in thrombosis risk reduction. Full article

Elevated levels of homocysteine in the blood plasma (hyperhomocysteinemia, HHCY) positively correlate with migraine symptoms in patients. Experimental studies show a higher sensitivity of rats with prenatal HHCY (pHHCY) to migraine symptoms like allodynia, photophobia, anxiety, and a higher excitability of meningeal trigeminal afferents. In the present study, the roles of purinergic mechanisms in the homocysteine-induced hyperexcitability of the trigeminal ganglion (TG) system using electrophysiological recordings from the trigeminal nerve, Ca²⁺ imaging of cells isolated from TG, and mast cell staining in meninges were investigated. Experiments were performed using rats with pHHCY born from females fed with a high-methionine-containing diet before and during pregnancy. Firstly, we found that lower concentrations of 4-aminopyridine, a K⁺-channel blocker, were able to induce an increase in the nociceptive activity of trigeminal afferents, supporting the hypothesis of the higher excitability of the trigeminal nerve of rats with pHHCY. Trigeminal afferents of rats with pHHCY were more sensitive to the exogenous application of the nonspecific agonist of purinergic ATP receptors. In neurons and satellite glial cells of TG of rats with pHHCY ATP, ADP (an agonist of metabotropic P2Y receptors) and BzATP (an agonist of ionotropic P2X with especially high potency for the P2X7 receptor) induced larger Ca²⁺ transients. The incubation of TG neurons in homocysteine for 24 h increased the ratio of neurons responding simultaneously to ATP and capsaicin. Moreover, rats with pHHCY exhibit a higher rate of degranulation of mast cells and increased response to the agonist of the P2X7 receptor BzATP application. In addition, higher levels of calcitonin gene-related peptide (CGRP) were found in rats with pHHCY. Our results suggest that chronic elevated levels of homocysteine induce the upregulation of ionotropic or metabotropic ATP receptors in neurons, satellite glial cells, and mast cells, which further provide inflammatory conditions and the sensitization of peripheral afferents underlying pain. Full article

Background/Objectives: Low testosterone levels and low vitamin D status are associated with increased cardiometabolic risk. The purpose of this study was to investigate whether vitamin D status determines the cardiometabolic effects of testosterone replacement therapy. Methods: The study population consisted of three groups of men with late-onset hypogonadism: vitamin D-naive individuals with 25-hydroxyvitamin D levels between 20 and 30 ng/mL (group I), males with 25-hydroxyvitamin D levels between 30 and 60 ng/mL receiving vitamin D supplementation because of previous low vitamin D status (group II), and vitamin D-naïve subjects with 25-hydroxyvitamin D levels between 30 and 60 ng/mL (group III). Circulating levels of total testosterone, 25-hydroxyvitamin D, glucose, insulin, lipids, uric acid, high-sensitivity C-reactive protein (hsCRP), homocysteine, fibrinogen, and urinary albumin-to-creatinine ratio (UACR) were assessed before and six months after intramuscular testosterone administration (250 mg every three weeks). Results: Group I differed from the remaining groups in baseline values of 25-hydroxyvitamin D, hsCRP, homocysteine, fibrinogen, UACR, and the Framingham Risk Score. In all three groups, testosterone injections increased plasma testosterone levels and had a neutral effect on 25-hydroxyvitamin D concentration. In groups II and III, the drug improved insulin sensitivity and reduced LDL cholesterol, uric acid, hsCRP, homocysteine, fibrinogen, and UACR. In group I, the impact of testosterone was limited to a small decrease in HDL cholesterol and hsCRP. Only in groups II and III did testosterone reduce the Framingham Risk Score. There were no differences in the strength of testosterone action between both groups. In groups II and III, the replacement-induced changes in insulin sensitivity, LDL cholesterol, uric acid, hsCRP, homocysteine, fibrinogen, UACR, and the Framingham Risk Score positively correlated with 25-hydroxyvitamin D concentration. Conclusions: The study results suggest that the cardiometabolic effects of exogenous testosterone in men with testosterone deficiency may be determined by vitamin D status. Full article

Background: Patients suffering from chronic kidney disease (CKD) have a high risk of premature cardiovascular morbidity and mortality. It has been suggested that elevated homocysteine (Hcy) or disturbances in the transmethylation pathway may contribute to this high cardiovascular risk burden due to epigenetic mechanisms. The objective of this study was to explore the prognostic value of Hcy, S-adenosylhomocysteine (SAH) and S-adenosylmethionine (SAM) (one-carbon (C1)-metabolites) among patients with CKD. Methods: Plasma concentrations of Hcy, SAM and SAH were measured among 297 participants with CKD (KDIGO GFR category G2–G5). The predefined endpoint was the occurrence of major cardiovascular events (MACE), defined as carotid, coronary and peripheral arterial revascularization, stroke, acute myocardial infarction, major amputation, cardiovascular death and all-cause mortality during a median (IQR) follow-up period of 4.0 [3.2; 4.3] years. Results: Among all participants, the median (IQR) of plasma Hcy, SAH, and SAM levels were 16.6 [13.5; 21.2] µmol/L, 41.5 [26.6; 63.9] nmol/L, 183.4 [151.1; 223.5] nmol/L, respectively. Estimated glomerular filtration rate (eGFR) correlated more strongly with plasma SAH (r = −0.588) than with SAM (r = −0.497) and Hcy (r = −0.424). During the follow-up period, 55 participants experienced MACE. In a univariate Kaplan Meier analysis, all three C1-metabolites were significantly associated with the occurrence of the primary outcome. In a Cox-regression analysis, the association between Hcy and MACE was not significant after adjustment for age and sex (hazard ratio (HR) and 95% confidence intervals (95% CI) for the 3rd vs. 1st tertile = 1.804 (0.868–3.974)). Both SAH and SAM were not associated with MACE after adjustment for age, sex and additionally for renal function markers (SAH: HR 3rd vs. 1st tertile 1.645 95% (0.654–4.411); SAM: HR 3rd vs. 1st tertile 1.920 95% CI (0.764–5.138)). Conclusions: In people with CKD, plasma Hcy, SAH and SAM were not independent predictors of MACE after adjustment for age, sex and renal function. Disturbed renal function may explain elevated C1-metabolites and disturbed transmethylation, while this pathway is not likely to be an appropriate access point to modify the risk of cardiovascular events in CKD patients. Full article

Atherosclerosis is accompanied by inflammation that underlies cardiovascular disease (CVD) and its vascular manifestations, including acute stroke, myocardial infarction, and peripheral artery disease, the leading causes of morbidity/mortality worldwide. The monolayer of endothelial cells formed on the luminal surface of arteries and veins regulates vascular tone and permeability, which supports vascular homeostasis. Endothelial dysfunction, the first step in the development of atherosclerosis, is caused by mechanical and biochemical factors that disrupt vascular homeostasis and induce inflammation. Together with increased plasma levels of low-density lipoprotein (LDL), diabetes, hypertension, cigarette smoking, infectious microorganisms, and genetic factors, epidemiological studies established that dysregulated metabolism of homocysteine (Hcy) causing hyperhomocysteinemia (HHcy) is associated with CVD. Patients with severe HHcy exhibit severe CVD and die prematurely due to vascular complications. Biochemically, HHcy is characterized by elevated levels of Hcy and related metabolites such as Hcy-thiolactone and N-Hcy-protein, seen in genetic and nutritional deficiencies in Hcy metabolism in humans and animals. The only known source of Hcy in humans is methionine released in the gut from dietary protein. Hcy is generated from S-adenosylhomocysteine (AdoHcy) and metabolized to cystathionine by cystathionine β-synthase (CBS) and to Hcy-thiolactone by methionyl-tRNA synthetase. Hcy-thiolactone, a chemically reactive thioester, modifies protein lysine residues, generating N-homocysteinylated (N-Hcy)-protein. N-Hcy-proteins lose their normal native function and become cytotoxic, autoimmunogenic, proinflammatory, prothrombotic, and proatherogenic. Accumulating evidence, discussed in this review, shows that these Hcy metabolites can promote endothelial dysfunction, CVD, and stroke in humans by inducing pro-atherogenic changes in gene expression, upregulating mTOR signaling, and inhibiting autophagy through epigenetic mechanisms involving specific microRNAs, histone demethylase PHF8, and methylated histone H4K20me1. Clinical studies, also discussed in this review, show that cystathionine and Hcy-thiolactone are associated with myocardial infarction and ischemic stroke by influencing blood clotting. These findings contribute to our understanding of the complex mechanisms underlying endothelial dysfunction, atherosclerosis, CVD, and stroke and identify potential targets for therapeutic intervention. Full article

Objective: This study aims to identify whether the development of insulin resistance (IR) induced by high selenium (Se) is related to serine deficiency via the inhibition of the de novo serine synthesis pathway (SSP) by the administrations of 3-phosphoglycerate dehydrogenase (PHGDH) inhibitor (NCT503) or exogenous serine in mice. Method: forty-eight male C57BL/6J mice were randomly divided into four groups: adequate-Se (0.1 mgSe/kg), high-Se (0.8 mgSe/kg), high-Se +serine (240 mg/kg/day), and high-Se +NCT503 (30 mg/kg, twice a week) for 5 months. The glucose tolerance test (GTT) and insulin tolerance test (ITT) were used to confirm the development of IR in mice with high-Se intake, and fasting blood glucose levels were measured monthly. The Se contents in plasma and tissues were detected by ICP-MS. The levels of insulin (INS), homocysteine (HCY), and serine in plasma were tested by ELISA. Western blot analyses were conducted to evaluate the protein expressions of glutathione peroxidase 1 (GPX1), selenoprotein P (SELENOP) and PHGDH, the PI3K-AKT-mTOR pathway, folate cycle (SHMT1, MTHFR), and methionine cycle (MS). Results: An IR model was developed in mice from the high-Se group with elevated fasting blood glucose and INS levels, impaired glucose tolerance, and reduced insulin sensitivity, but not in both the high-Se +serine group and the high-Se +NCT503 group. Compared with the high-Se and high-Se +serine groups, the expressions of GPX1 and SELENOP significantly decreased for the high-Se +NCT503 group in the liver, muscle, and pancreas tissues. The expression of PHGDH of high-Se group was significantly higher than that of the adequate-Se group in the liver (p < 0.05) and pancreas (p < 0.001). Also, the expected high expression of PHGDH was effectively inhibited in mice from the high-Se +serine group but not from the high-Se +NCT503 group. The expression of p-AKT (Ser-473) for the high-Se group was significantly lower than that of the adequate-Se group in the liver, muscle, and pancreas. Conclusions: The IR induced by high-Se intake in the body has been confirmed to be partially due to serine deficiency, which led to the initiation of SSP to produce endogenous serine. The supplementations of exogenous serine or inhibitors of PHGDH in this metabolic pathway could be used for the intervention. Full article