Plasma Hcy Levels Research Articles

The binding of autotaxin to integrins mediates hyperhomocysteinemia-potentiated platelet activation and thrombosis in mice and humans

AbstractHyperhomocysteinemia (HHcy) is associated with an exaggerated platelet thrombotic response at sites of vascular injury. In this study, human medical examination showed that elevated human plasma Hcy levels correlated positively with enhanced blood coagulation and platelet activity, suggesting that humans with HHcy are more prone to thrombus formation at the sites of vascular injury. Accordingly, we observed accelerated platelet activation, primary hemostasis, and thrombus formation in apolipoprotein E-deficient (ApoE−/−) mice with acute or chronic HHcy. Upon homocysteine (Hcy) administration in C57BL/6J mice, platelet aggregation, spreading and clot retraction were markedly induced. More important, Hcy increased the affinity of platelet integrin αIIbβ3 with ligands and enhanced integrin outside-in signaling by promoting membrane phosphatidylserine exposure in vitro. Mechanistically, lipidomics analysis showed that lysophosphatidylcholines were the primary metabolites leading to clustering of HHcy-stimulated platelets. Cytosolic phospholipase A2 (cPLA2) activity and autotaxin (ATX, a secreted lysophospholipase D) secretion were upregulated by Hcy, leading to membrane phospholipid hydrolysis and PS exposure. Moreover, secreted ATX directly interacted with integrin β3. Inhibitors of cPLA2 and ATX activity blocked integrin αIIbβ3 outside-in signaling and thrombosis in HHcy ApoE−/− mice. In this study, we identified a novel mechanism by which HHcy promotes platelet membrane phospholipid catabolism and extracellular ATX secretion to activate integrin outside-in signaling, consequently exacerbating thrombosis and the results revealed an innovative approach to treating HHcy-related thrombotic diseases.

Variation of homocysteine levels in rheumatoid arthritis patients: relationship to inflammation, cardiovascular risk factors, and methotrexate.

The aim of this study was to evaluate the variation of homocysteine (Hcy) levels in patients with rheumatoid arthritis (RA) and to analyze the relationship to inflammatory parameters, cardiovascular risk, and methotrexate (MTX). This cross-sectional study assessed disease activity and treatment in RA patients. The European League Against Rheumatism (EULAR) 2015 HeartSCORE was performed for cardiovascular (CV) risk estimation and levels of plasma Hcy, serum folate concentrations, vitaminB12, and erythrocyte sedimentation rate (ESR) were measured. A total of 103participants with mean age 53 ± 10years and mean disease duration 10.55 ± 7.34years were included. Patients were treated with MTX in 69.9% of cases and corticosteroid in 80.5% of cases. Of all patients, 13% had acardiovascular inheritance, 25% were hypertensive, and 18% had diabetes. The EULAR 2015 HeartSCORE was high and very high (≥5%) in 35% of cases. Mean Hcy level was 12.54 ± 4.2 µmol/L [6.89-32.92] and hyperhomocysteinemia was noted in 20.4% of patients. Analytic study demonstrated that hyperhomocysteinemia was associated with male gender (p = 0.01), MTX use (p = 0.01), smoking (p = 0.008), renal failure (p = 0.04), and high disease activity (p = 0.05), but there was no association with the HeartSCORE (p = 0.23). Hcy level was negatively correlated with folate (p = 0.009) and vitaminB12 level (p = 0.02) and positively with age (p = 0.01), C‑reactive protein (CRP; p = 0.05), and Simplified Disease Activity Index (SDAI; p = 0.03). In multivariate logistic regression analysis, current MTX use, levels of vitaminB12 and creatine, and Clinical Disease Activity Index (CDAI) appeared to be independent factors associated with hyperhomocysteinemia. MTX use, CDAI, and the levels of vitaminB12 and creatine are independent factors associated with hyperhomocysteinemia.

Association between high BMI and high homocysteine levels in Chinese patients with bipolar disorder

BackgroundBipolar disorder (BD) has been associated with an increased prevalence of weight gain and abnormally elevated plasma homocysteine (Hcy) levels. However, the relationship between BMI and Hcy in BD patients has not been investigated. This study aimed to explore this relationship in Chinese patients with BD. MethodsPlasma Hcy levels, socio-demographic parameters, clinical and anthropometric data were collected from 195 BD inpatients and 84 healthy controls. The level of plasma Hcy was determined by high-performance liquid chromatography. Body mass index (BMI) was calculated by body weight divided by the square of the height. The participants were divided into a high BMI group and a low BMI group using 24 kg/m2 as a threshold. ResultsThe prevalence of high BMI was slightly elevated in BD patients in comparison to healthy controls. Patients with elevated BMI had significantly higher Hcy levels than patients with low BMI. Hcy level was an independent contributor of the occurrence of high BMI in BD patients. The level of Hcy was positively correlated with BMI in BD patients. In addition, depressive episodes of BD were positively correlated with the prevalence of high BMI and married BD patients were more likely to have high BMI levels. ConclusionsThere is a close relationship between BMI and plasma Hcy levels in patients with BD, suggesting that Hcy may be an important indicator for BD-induced weight gain. This finding provides a new avenue for weight management of BD patients and to help avoid the potential risk of cardiovascular diseases.

Elevated homocysteine levels in patients with heart failure: A systematic review and meta-analysis.

Background:Elevated homocysteine (Hcy) levels showed increasing significance as the predisposing factor for the pathogenesis of atherosclerotic sequelae, including cardiovascular mortality, coronary artery disease, and stroke. There is increasing evidence linking plasma Hcy levels and heart failure (HF). The association between the elevated level of plasma Hcy and HF was examined by meta-analysis and systematic review in this study.Methods:The PubMed and ScienceDirect databases until April 2020 were utilized to collect previous literature on plasma Hcy levels and the potential relation to HF. The pooled effects were evaluated depending on standardized mean differences (SMDs) with 95% confidence intervals (CIs), and the calculation was performed using Stata 12 software. Potential sources of heterogeneity were assessed with subgroup analysis and sensitivity analysis.Results:A total of 12 research projects including 5506 subjects were selected. For pooled effect, the results confirmed that patients with HF had higher Hcy levels than the control subjects (SMD,1.148 and 95%CI, [0.715, 1.581]). Based on the classification of New York Heart Association (NYHA), the Hcy levels for the group of NYHA I or II (SMD, 1.484 and 95% CI, [0.442, 2.527]) and the group of NYHA III or IV (SMD, 3.361 and 95% CI, [1.902, 4.820]) were significantly increased compared to controls, while the increase was more intensive for the group of NYHA III or IV. Subgroup analyses revealed similar results.Conclusion:Our meta-analysis identified that plasma Hcy levels were significantly elevated in HF patients compared to control subjects, which is positively related to the advancement of NYHA class.

Multiple roles of haem in cystathionine β-synthase activity: implications for hemin and other therapies of acute hepatic porphyria.

The role of haem in the activity of cystathionine β-synthase (CBS) is reviewed and a hypothesis postulating multiple effects of haem on enzyme activity under conditions of haem excess or deficiency is proposed, with implications for some therapies of acute hepatic porphyrias. CBS utilises both haem and pyridoxal 5′-phosphate (PLP) as cofactors. Although haem does not participate directly in the catalytic process, it is vital for PLP binding to the enzyme and potentially also for CBS stability. Haem deficiency can therefore undermine CBS activity by impairing PLP binding and facilitating CBS degradation. Excess haem can also impair CBS activity by inhibiting it via CO resulting from haem induction of haem oxygenase 1 (HO 1), and by induction of a functional vitamin B6 deficiency following activation of hepatic tryptophan 2,3-dioxygenase (TDO) and subsequent utilisation of PLP by enhanced kynurenine aminotransferase (KAT) and kynureninase (Kynase) activities. CBS inhibition results in accumulation of the cardiovascular risk factor homocysteine (Hcy) and evidence is emerging for plasma Hcy elevation in patients with acute hepatic porphyrias. Decreased CBS activity may also induce a proinflammatory state, inhibit expression of haem oxygenase and activate the extrahepatic kynurenine pathway (KP) thereby further contributing to the Hcy elevation. The hypothesis predicts likely changes in CBS activity and plasma Hcy levels in untreated hepatic porphyria patients and in those receiving hemin or certain gene-based therapies. In the present review, these aspects are discussed, means of testing the hypothesis in preclinical experimental settings and porphyric patients are suggested and potential nutritional and other therapies are proposed.

Simvastatin increases circulating endothelial progenitor cells and inhibits the formation of intracranial aneurysms in rats with diet-induced hyperhomocysteinemia

Background and purposeEndothelial dysfunction triggers early pathological changes in artery, leading to the formation of intracranial aneurysm (ICA). Increase in plasma homocysteine (Hcy) impairs endothelium and endothelial progenitor cells (EPCs) are critical in repairing damaged endothelium. The aim of this study was to assess the impact of simvastatin on ICA formation in rats with hyperhomocysteinemia (HHcy). MethodsICAs were induced in Male Sprague–Dawley rats after surgical induction in the presence of HHcy induced by a high L-methionine diet with or without oral simvastatin treatment. The size and media thickness of ICAs were evaluated 2 months after aneurysm induction. EPCs and serum vascular endothelial grow factor (VEGF) were measured be flow cytometry and ELISA respectively. Plasma Hcy levels and expression of VEGF, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), matrix metalloproteinase-2 (MMP-2), and MMP-9 in aneurysmal walls were examined and correlated with ICA formation. ResultsHHcy accelerates ICA formation and rats treated with simvastatin exhibited a significant increase in media thickness and a reduction in aneurysmal size. Simvastatin increased levels of circulating EPCs and decreased iNOS, MMP-2, MMP-9 and VEGF mRNA levels, while increased eNOS mRNA in aneurysmal tissue. ConclusionIn a rat model, HHcy reduces circulating EPCs and accelerates ICA formation. Simvastatin treatment increases circulating EPCs and inhabits the formation of ICA. We have shown a close association among circulating EPCs, biochemical markers related to vascular remodeling and the formation of ICA.

Homocysteine Causes Endothelial Dysfunction via Inflammatory Factor-Mediated Activation of Epithelial Sodium Channel (ENaC).

BackgroundHyperhomocysteinemia (HHcy) causes cardiovascular diseases via regulating inflammatory responses. We investigated whether and how the epithelial sodium channel (ENaC), a recently identified ion channel in endothelial cells, plays a role in HHcy-induced endothelial dysfunction.MethodsCell-attached patch-clamp recording in acute split-open aortic endothelial cells, western blot, confocal imaging, and wire myograph combined with pharmacological approaches were used to determine whether HHcy-mediated inflammatory signaling leads to endothelial dysfunction via stimulating ENaC.ResultsThe data showed that 4 weeks after L-methionine diet the levels of plasma Hcy were significantly increased and the ENaC was dramatically activated in mouse aortic endothelial cells. Administration of benzamil, a specific ENaC blocker, ameliorated L-methionine diet-induced impairment of endothelium-dependent relaxation (EDR) and reversed Hcy-induced increase in ENaC activity. Pharmacological inhibition of NADPH oxidase, reactive oxygen species (ROS), cyclooxygenase-2 (COX-2)/thromboxane B2 (TXB2), or serum/glucocorticoid regulated kinase 1 (SGK1) effectively attenuated both the Hcy-induced activation of endothelial ENaC and impairment of EDR. Our in vitro data showed that both NADPH oxidase inhibitor and an ROS scavenger reversed Hcy-induced increase in COX-2 expression in human umbilical vein endothelial cells (HUVECs). Moreover, Hcy-induced increase in expression levels of SGK-1, phosphorylated-SGK-1, and phosphorylated neural precursor cell-expressed developmentally downregulated protein 4-2 (p-Nedd4-2) in HUVECs were significantly blunted by a COX-2 inhibitor.ConclusionWe show that Hcy activates endothelial ENaC and subsequently impairs EDR of mouse aorta, via ROS/COX-2-dependent activation of SGK-1/Nedd4-2 signaling. Our study provides a rational that blockade of the endothelial ENaC could be potential method to prevent and/or to treat Hcy-induced cardiovascular disease.

Severe homocysteinemia in two givosiran-treated porphyria patients: is free heme deficiency the culprit?

Givosiran is a novel approach to treat patients with acute intermittent porphyrias (AIP) by silencing of ∂-ALA-synthase 1, the first enzyme of heme biosynthesis in the liver. We included two patients in the Envision study who responded clinically well to this treatment. However, in both patients, therapy had to be discontinued because of severe adverse effects: One patient (A) developed local injection reactions which continued to spread all over her body with increasing number of injections and eventually caused a severe systemic allergic reaction. Patient B was hospitalized because of a fulminant pancreatitis. Searching for possible causes, we also measured the patients plasma homocysteine (Hcy) levels in fluoride-containing collection tubes: by LC–MS/MS unexpectedly, plasma Hcy levels were 100 and 200 in patient A and between 100 and 400 μmol/l in patient B. Searching for germline mutations in 10 genes that are relevant for homocysteine metabolism only revealed hetero- and homozygous polymorphisms in the MTHFR gene. Alternatively, an acquired inhibition of cystathionine-beta-synthase which is important for homocysteine metabolism could explain the plasma homocysteine increase. This enzyme is heme-dependent: when we gave heme arginate to our patients, Hcy levels rapidly dropped. Hence, we conclude that inhibition of ∂-ALA-synthase 1 by givosiran causes a drop of free heme in the hepatocyte and therefore the excessive increase of plasma homocysteine. Hyperhomocysteinemia may contribute to the adverse effects seen in givosiran-treated patients which may be due to protein-N-homocysteinylation.

Appraising the Causal Association of Plasma Homocysteine Levels With Atrial Fibrillation Risk: A Two-Sample Mendelian Randomization Study.

BackgroundAlthough several observational studies have suggested an association of elevated plasma homocysteine (Hcy) levels with increased risk of atrial fibrillation (AF), it remains unclear whether this association reflects causality. In this study, we aimed to investigate the causal association of plasma Hcy levels with AF risk.MethodsA two-sample Mendelian randomization (MR) study was designed to investigate the causal association of Hcy with AF. Summary data on association of single nucleotide polymorphisms (SNPs) with Hcy were extracted from the hitherto largest genome-wide association study (GWAS) with up to 44,147 individuals, and statistics data on association of SNPs with AF were obtained from another recently published GWAS with up to 1,030,836 individuals. SNPs were selected at a genome-wide significance threshold (p < 5 × 10–8). Fixed-effect inverse variance weighting (IVW) method was used to calculate the causal estimate. Other statistical methods and leave-one-out analysis were applied in the follow-up sensitivity analyses. MR-Egger intercept test was conducted to detect the potential directional pleiotropy.ResultsIn total, nine SNPs were identified as valid instrumental variables in our two-sample MR analysis. Fixed-effect IVW analysis indicated no evidence of causal association of genetically predicted Hcy with AF. The odds ratio (OR) and 95% confidence interval (CI) of AF per standard deviation (SD) increase in Hcy were 1.077 (0.993, 1.168), p = 0.075. Similar results were observed in the sensitivity analyses. MR-Egger intercept test suggested no evidence of potential horizonal pleiotropy.ConclusionsThis two-sample MR analysis found no evidence to support causal association of Hcy with AF.

Kidney function decline is associated with an accelerated increase in plasma homocysteine in older adults: a longitudinal study.

Few studies have been conducted to investigate the association of kidney function decline with the trajectories of homocysteine (Hcy) over time, using repeated measurements. We aimed to investigate the association of kidney function with changes in plasma Hcy levels over time. Data were collected from the Rugao Longevity and Ageing Study. In detail, plasma Hcy and creatinine levels were measured in both waves (waves 2, 3 and 4) during the 3·5-year follow-up (n 1135). Wave 2 was regarded as the baseline survey. The estimated glomerular filtration rate (eGFR) was calculated based on creatinine. Subjects were categorised into four groups according to quartiles of eGFR at baseline. Linear mixed-effect models were used to investigate the association of eGFR with subsequent plasma Hcy levels. The mean eGFR at baseline was 90·84 (sd 11·42) ml/min per 1·73 m2. The mean plasma Hcy level was 14·09 (sd 6·82) at baseline and increased to 16·28 (sd 8·27) and 17·36 (sd 10·39) μmol/l during follow-ups. In the crude model, the interaction between time and eGFR at baseline was significant (β = -0·02, 95 % CI -0·02, -0·01, P = 0·002). After adjusting for confounding factors, a significant relationship remained (β = -0·02, 95 % CI -0·02, -0·01, P = 0·003), suggesting that kidney function decline at baseline was associated with a faster increase in Hcy levels. Kidney function decline is associated with a more pronounced increase in plasma Hcy levels. Further studies with longer follow-up periods and larger sample sizes are needed to validate our findings.

Evaluation of the relationship between homocysteine levels and bone mineral density in postmenopausal women

Objective The current study aimed to evaluate the relationship between homocysteine (Hcy) levels and bone mineral density (BMD) in postmenopausal women. Methods The present, cross-sectional study included 760 postmenopausal women. The following variables were recorded: age, age at menopause, body mass index (BMI), BMD (measured by dual-energy X-ray absorptiometry [DXA] scanning and expressed as lumbar, femoral neck and total hip T-scores), smoking status, biochemical parameters (Hcy, creatinine, calcium, phosphorus, vitamin D and parathormone levels) and vitamin D supplementation. Results The mean age of the sample population was 56.4 ± 5.77 years and the mean age at menopause was 49.9 ± 3.62 years. The mean BMI was 25.2 ± 4.49 kg/m2. In the current study, a comparison of the subjects with osteoporosis, osteopenia and normal BMD revealed that the subjects in the low BMD group were significantly older (p < 0.001), had a lower age at menopause (p < 0.001) and had lower BMI (p < 0.001). There was no statistically significant difference among the groups with regard to the plasma levels of Hcy (p = 0.946). The levels of Hcy were positively correlated to the creatinine levels (r = 0.21). The present study did not observe any significant correlations between the Hcy levels and other parameters. Conclusions In the present study, 15.3% of the subjects had hyperhomocysteinemia and 62.11% had low BMD. The current results obtained from a group of postmenopausal women suggest that the plasma levels of Hcy are not related to BMD in the lumbar spine (L1–L4), femoral neck and total hip. In the current study, age, age at menopause and low BMI were observed to be associated with low BMD.

Effects of vitamin B12, folate, and entacapone on homocysteine levels in levodopa-treated Parkinson’s disease patients: A randomized controlled study

IntroductionPrevious studies have suggested a significant increase in plasma homocysteine (Hcy) levels in levodopa-treated Parkinson’s disease (PD) patients, and vitamin B12 and folate supplementation may decrease Hcy levels. However, the effects of catechol-O-methyltransferase inhibitors on levodopa-induced increase in Hcy levels were conflicting. The aim of this study was to evaluate whether Hcy levels are increased in levodopa-treated PD patients and to evaluate the effects of vitamin B12 and folate or entacapone on Hcy levels in levodopa-treated PD patients. MethodsWe analyzed and compared plasma Hcy levels in 20 levodopa-naïve PD patients and 42 levodopa-treated PD patients, followed by randomized assignment of 42 levodopa-treated patients to treatment groups with either vitamin B12 and folate, entacapone, or no medication. ResultsPlasma Hcy levels in levodopa-treated PD patients were higher than those in the control group, but the difference was not statistical significant (15.25 ± 6.70 and 13.13 ± 4.68, P = 0.216). Patients treated with vitamin B12 and folate had a significant decrease in plasma Hcy levels (P < 0.001). In the entacapone group, Hcy levels were mildly decreased, but the change did not reach statistical significance. ConclusionLevodopa-treated PD patients had higher plasma Hcy than levodopa-naive PD patients. Unlike entacapone, combination supplementation with vitamin B12 and folate was associated with significantly decreased plasma Hcy. We suggest that plasma Hcy levels should be monitored during levodopa treatment, and supplementation with inexpensive vitamin B12 and folate is beneficial for levodopa-treated patients.

Gender differences in risk factors for high plasma homocysteine levels based on a retrospective checkup cohort using a generalized estimating equation analysis

BackgroundHyperhomocysteinemia (HHcy) is associated with various health problems, but less is known about the gender differences in risk factors for high plasma homocysteine (Hcy) levels.MethodsIn this study, a retrospective study was carried out on 14,911 participants (7838 males and 7073 females) aged 16–102 years who underwent routine checkups between January 2012 and December 2017 in the Health Management Department of Xuanwu Hospital, China. Anthropometric measurements, including body mass index (BMI) and waist-to-hip ratio, were collected. Fasting blood samples were collected to measure the biochemical indexes. The outcome variable was Hcy level, and a generalized estimating equation (GEE) analysis was used to identify the associations of interest based on gender.ResultsMales exhibited increased Hcy levels (16.37 ± 9.66 vs 11.22 ± 4.76 μmol/L) and prevalence of HHcy (37.0% vs 11.3%) compared with females. Hcy levels and HHcy prevalence increased with age in both genders, except for the 16- to 29-year-old group. GEE analysis indicated that irrespective of gender, aspartate aminotransferase, creatinine, uric acid, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels were positively correlated with Hcy levels, and alanine aminotransferase, total cholesterol and glucose were negatively correlated with Hcy levels. However, age, BMI and triglycerides (TGs) were positively correlated with Hcy levels exclusively in females.ConclusionsGender differences in risk factors for high plasma Hcy levels were noted. Although common correlational factors existed in both genders, age, BMI and TGs were independent risk factors for Hcy levels specifically in females.

A Mendelian Randomization Study of Plasma Homocysteine Levels and Cerebrovascular and Neurodegenerative Diseases.

Background: Homocysteine (Hcy) is a toxic amino acid and hyperhomocysteinemia (HHcy) was reported to be associated with both cerebrovascular disease and neurodegenerative disease. Our aim was to assess the causal link between plasma Hcy level and cerebrovascular and neurodegenerative diseases through a Mendelian randomization (MR) study. Methods: A two-sample MR study was performed to infer the causal link. We extracted the genetic variants (SNPs) associated with plasma Hcy level from a large genome-wide association study (GWAS) meta-analysis. The main MR analysis was performed using the inverse variance-weighted method. Additional analyses were further performed using MR-Egger intercept and Cochran’s Q statistic to detect the heterogeneity or pleiotropy of our findings. Results: Thirteen Hcy-associated SNPs were selected as instrumental variables. The results showed evidence of a causal link between plasma Hcy level and ischemic stroke (IS) caused by small artery occlusion (SAS, OR = 1.329, 95% CI 1.047–1.612, p = 0.048). Meanwhile, there was no evidence of association between plasma Hcy level and other types of IS, transient ischemic attack (TIA), or neurodegenerative disease. The MR-Egger intercept test indicated no evidence of directional pleiotropy. Results of additional MR analysis indicated that blood pressure (BP) and type 2 diabetes mellitus (T2DM) serve as influencers in the association. Conclusion: The MR study found a little causal link between plasma Hcy level and SAS. The link is likely to be influenced by other risk factors like BP and T2DM.

LOW-DOSE FOLIC ACID PROTECTS AGAINST ADVERSE CARDIAC REMODELING IN SPONTANEOUSLY HYPERTENSIVE RATS WITH HYPERHOMOCYSTEINEMIA

Objective: The interaction between hypertension and hyperhomocysteinemia (Hhcy) leads to adverse myocardial and coronary vascular remodeling in the hypertensive heart, resulting in impaired diastolic function. Folic acid (FA) is a free radical scavenger with antioxidant properties that effectively reduces homocysteine (Hcy) levels. The aim of this study was to evaluate whether lowering plasma homocysteine (Hcy) with different dose of folic acid (FA) could against Hhcy-induced myocardial injury in spontaneously hypertensive rats (SHRs) and its possible mechanisms. Design and method: Thirty-two adult male SHRs were randomly divided into four groups (n = 8/group), namely control group, Hhcy intervention group, Hhcy + Low-dose FA treatment group (0.4 mg/Kg·d), Hhcy + High-dose FA treatment group (4 mg/Kg·d), and then three Hhcy groups were subcutaneously injected 2% DL- homocysteine 5 ml/Kg. FA intervention started after 4 weeks’ Hcy injection. The total duration of the trial was 16 weeks. Cardiac echocardiography was performed at the last week. The Systolic blood pressure (SBP), diastolic blood pressure (DBP), plasma Hcy, serum malondialdehyde (MDA), superoxide dismutase (SOD) were measured, and Masson's trichrome stain to enable evaluation of collagen deposition under a microscope. Furthermore, the levels of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase 1 (HO-1) protein were detected by extraction of nuclear protein from cardiac tissue. Results: Intragastric administration of FA significantly reduced plasma Hcy levels. Serum SOD was significantly increased and serum MDA were also significantly attenuated by FA. Low-dose folic acid is more effective than high-dose folic acid in relieving Hhcy-induced anomalies in the heart of SHRs, such as the decline in cardiac diastolic function, perivascular collagen accumulation, and arteriolar wall thickening. FA increased the expression of Nrf2 and HO-1, and exhibited a protective effect against Hhcy-induced oxidative stress (OS), and there were no significant difference between high-dose and low-dose FA groups. Conclusions: Low-dose FA treatment can better protect against Hhcy-induced myocardial injury in SHRs, which may be due to its inhibition of OS and upregulation of Nrf2/HO-1 pathway.

Folic acid alleviates jaundice of phenylhydrazine (PHA)-induced neonatal rats by reducing Lys-homocysteinylation of albumin.

Neonatal jaundice is a common symptom that occurs in neonates during the first month of their life and is generally divided into physiological and pathological subtypes. In serious cases, pathological neonatal jaundice frequently shows complications including seizures, cerebral palsy, and kernicterus. However, due to the unclear pathogenesis of pathological neonatal jaundice, effective drugs for this disease remain unsatisfied. In the present study, we first estimated the protective effects of folic acid (FA) on phenylhydrazine (PHA) or homocysteine (Hcy)-injected neonatal rats (2-3 days aged). Intriguingly, we found that FA significantly decreased the elevated total bilirubin (TBIL) and direct bilirubin (DBIL) concentration, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) activity in PHA- or Hcy-injected rats, indicating that FA improves liver functions. Meanwhile, our results also showed that the plasma Hcy level and N-homocysteinylation (N-Hcy) modification of albumin were significantly elevated in the jaundice rats, which were obviously reversed after FA administration. Furthermore, we identified a novel N-Hcy modification site K545 of human serum albumin (HSA) using LC-MS/MS, and the mutagenesis assay in HEK293 further validated these observations. Besides, we demonstrated that the N-Hcy modification of albumin functionally inhibits the bilirubin-binding ability of albumin without altering its protein level both in vitro and in vivo. Altogether, we highlight a mechanism that FA reduces the plasma Hcy level and thereby enhance the bilirubin-binding ability of albumin, which may provide a novel therapeutic strategy for the treatment of pathological neonatal jaundice.

Impact of combined elevations of homocysteine and asymmetric dimethylarginine on all-cause death ― The Tanushimaru Study

BackgroundBoth homocysteine (Hcy) and asymmetric dimethylarginine (ADMA) induce endothelial dysfunction. However, the impact of both elevations on all-cause death is not known. We investigated the association between elevations of Hcy or ADMA and all-cause death in a general population. MethodsA total of 517 subjects (224 men, 293 women; mean age, 62.8 years) were recruited from a population-based survey in 1999 in Tanushimaru, and we measured fasting plasma Hcy and ADMA levels. We followed them up for over 20 years and examined the effect on mortality using Cox proportional hazard regression model. ResultsThe mean follow-up years were 17.7 (1.8-20.8). In this period, 182 subjects have died (35.2%). The correlation between Hcy and ADMA was high (r=0.194; p<0.001). With Cox regression analysis after adjustments for age and sex, elevated log transformed Hcy levels were significantly associated with all-cause death (p=0.028). When Hcy and ADMA levels were divided into quintiles, the hierarchical model showed the synergistic effect of Hcy and ADMA on all-cause death. ConclusionsThis is the first report that we have measured Hcy and ADMA levels simultaneously in this community-dwelling Japanese, and we demonstrated that combined elevations of Hcy and ADMA had big impact on all-cause death in this epidemiological study.

Homocysteine-related alterations of 18F-FDG brain pattern in metabolic diseases.

Since hyperhomocysteinaemia (HHcys) is implicated as a risk factor for the development of neurodegeneration, and is associated with the development of metabolic diseases,we aimed at analysing the effect of homocysteine (Hcys) on regional fluorine-18-fluorodeoxyglucose (18F-FDG) brain metabolismin 51 controlled type 2 diabetic and in 48 non-DM obese participants. Plasma Hcys levels were measured by an immunoassay. Homocysteine-related 18F-FDG regional brain metabolism was evaluated applying 18F-FDG PET/CT using magnetic resonance imaging (MRI)-based brain template for statistical parametric mapping (SPM) analysis. Homocysteine-related decreased 18F-FDG uptake was shown in the right middle temporal gyrus in the whole population. Diabetics with Hcys above the reference limit expressed decreased glucose metabolismin the left calcarine cortex compared to the obese with HHcys. Regional metabolic alterations evoked on the basis of HHcys draw attention to the potential risk of neurodegeneration caused by metabolic disturbances.

Effect of methionine feeding on oxidative stress, intracellular calcium and contractility in cardiomyocytes isolated from male and female rats

Homocysteine (Hcy) is a breakdown product of methionine metabolism. The risk of cardiovascular disease (CVD) correlates with an increase in plasma Hcy levels. The aim of this study was to investigate whether 1% methionine supplementation of adult rats altered intracellular reactive oxygen species (ROS) generation, intracellular Ca2+ content, and contractile activity in freshly isolated cardiomyocytes. This was measured under normal conditions and during oxidative stress in freshly isolated cardiomyocytes. Single rat cardiomyocytes from both sexes were isolated by enzymatic and mechanical dispersion techniques. Fluorescence microscopy was used to measure ROS production and intracellular Ca2+ concentration. Cell contraction was measured using a video camera. During exposure to 200μM, H2O2 female cardiomyocytes produced significantly fewer ROS and had a higher intracellular Ca2+ concentration compared to male cardiomyocytes in control and methionine-fed conditions. The contractility of cardiomyocytes isolated from male rats was insignificantly decreased after methionine feeding compared to control, while the contractility of cardiomyocytes from female rats insignificantly reduced after methionine feeding and acute exposure to oxidative stress. These findings provide evidence that during exposure to 200μM H2O2, cardiomyocytes from female rats produce less ROS and have higher intracellular Ca2+ levels. There were no significant effects on contractility in cardiomyocytes from either gender and under any of the different conditions.

The association between serine hydroxymethyl transferase 1 gene hypermethylation and ischemic stroke.

This study aimed to determine the correlation between serine hydroxymethyl transferase 1 (SHMT1) gene methylation and ischemic stroke. A total of 202 age- and sex-matched individuals were included. Quantitative methylation-specific polymerase chain reaction (qMSP-PCR) was used to analyze the DNA methylation level. The plasma homocysteine (Hcy) concentration was much higher in ischemic cases than in controls (p = 0.009), while the high-density lipoprotein (HDL) levels in stroke cases were considerably lower than in controls (p = 0.005). A significantly higher level of SHMT1 methylation was observed in the ischemic strokes (58.82 ± 17.83%) compared to that in the controls (42.59 ± 20.76%, p < 0.001). The SHMT1 methylation level was strongly correlated with HDL concentration in the healthy controls (r = 0.517, p < 0.001), while the high plasma level of Hcy showed strong association with SHMT1 methylation in ischemic strokes (r = 0.346, p < 0.001). Receiver operating characteristic (ROC) analysis of curve indicated that SHMT1 methylation has been an acceptable indicator for ischemic stroke in female patients [all sexes, area under the curve (AUC) = 0.71, p < 0.001; male patients AUC = 0.62, p = 0.032; and female patients AUC = 0.79, p < 0.001] and in all ages (AUC = 0.71, p < 0.001). In our samples, DNA methylation levels of the STHMI gene were significantly correlated with ischemic stroke in Han Chinese. STHMI hypermethylation was significantly associated with the high Hcy concentration in ischemic stroke and had value as a potential indicator for female ischemic stroke.