Efficacy of Folic Acid Therapy in Patients with Hyperhomocysteinemia

Uncovering the Hidden Dangers and Molecular Mechanisms of Excess Folate: A Narrative Review

This review delves into the intricate relationship between excess folate (vitamin B9) intake, especially its synthetic form, namely, folic acid, and its implications on health and disease. While folate plays a pivotal role in the one-carbon cycle, which is essential for DNA synthesis, repair, and methylation, concerns arise about its excessive intake. The literature underscores potential deleterious effects, such as an increased risk of carcinogenesis; disruption in DNA methylation; and impacts on embryogenesis, pregnancy outcomes, neurodevelopment, and disease risk. Notably, these consequences stretch beyond the immediate effects, potentially influencing future generations through epigenetic reprogramming. The molecular mechanisms underlying these effects were examined, including altered one-carbon metabolism, the accumulation of unmetabolized folic acid, vitamin-B12-dependent mechanisms, altered methylation patterns, and interactions with critical receptors and signaling pathways. Furthermore, differences in the effects and mechanisms mediated by folic acid compared with natural folate are highlighted. Given the widespread folic acid supplementation, it is imperative to further research its optimal intake levels and the molecular pathways impacted by its excessive intake, ensuring the health and well-being of the global population.

Emodin protects against homocysteine-induced cardiac dysfunction by inhibiting oxidative stress via MAPK and Akt/eNOS/NO signaling pathways

Elevated levels of plasma homocysteine (Hcy) causes severe cardiac dysfunction, which is closely associated with oxidative stress. Emodin, a naturally occurring anthraquinone derivative, has been shown to exert antioxidant and anti-apoptosis activities. However, whether emodin could protect against Hcy-induced cardiac dysfunction remains unknown. The current study aimed to investigate the effects of emodin on the Hcy-induced cardiac dysfunction and its molecular mechanisms. Rats were fed a methionine diet to establish the animal model of hyperhomocysteinemia (HHcy). H9C2 cells were incubated with Hcy to induce a cell model of Hcy-injured cardiomyocytes. ELISA, HE staining, carotid artery and left ventricular cannulation, MTT, fluorescence staining, flow cytometry and western blotting were used in this study. Emodin significantly alleviated the structural damage of the myocardium and cardiac dysfunction from HHcy rats. Emodin prevented apoptosis and the collapse of MMP in the Hcy-treated H9C2 cells in vitro. Further, emodin reversed the Hcy-induced apoptosis-related biochemical changes including decreased Bcl-2/Bax protein ratio, and increased protein expression of Caspase-9/3. Moreover, emodin suppressed oxidative stress in Hcy-treated H9C2 cells. Mechanistically, emodin significantly inhibited the Hcy-activated MAPK by reducing ROS generation in H9C2 cells. Furthermore, emodin upregulated NO production by promoting the protein phosphorylation of Akt and eNOS in injured cells. The present study shows that emodin protects against Hcy-induced cardiac dysfunction by inhibiting oxidative stress via MAPK and Akt/eNOS/NO signaling pathways.

Effects of low-dose B vitamins plus betaine supplementation on lowering homocysteine concentrations among Chinese adults with hyperhomocysteinemia: a randomized, double-blind, controlled preliminary clinical trial

PURPOSE

To test the hypothesis that daily supplementation with low-dose B vitamins plus betaine could significantly reduce plasma homocysteine concentrations in Chinese adults with hyperhomocysteinemia and free from background mandatory folic acid fortification.

METHODS

One hundred apparently healthy adults aged 18-65 years with hyperhomocysteinemia were recruited in South China from July 2019 to June 2021. They were randomly assigned to either the supplement group (daily supplementation: 400 μg folic acid, 8 mg vitamin B₆, 6.4 μg vitamin B₁₂ and 1 g betaine) or the placebo group for 12 weeks. Fasting venous blood was collected at baseline, week 4 and week 12 to determine the concentrations of homocysteine, folate, vitamin B₁₂ and betaine. Generalized estimation equations were used for statistical analysis.

RESULTS

Statistically significant increments in blood concentrations of folate, vitamin B₁₂ and betaine after the intervention in the supplement group indicated good participant compliance. At baseline, there were no significant differences in plasma homocysteine concentration between the two groups (P = 0.265). After 12-week supplementation, compared with the placebo group, there was a significant reduction in plasma homocysteine concentrations in the supplement group (mean group difference - 3.87; covariate-adjusted P = 0.012; reduction rate 10.1%; covariate-adjusted P < 0.001). In the supplement group, the decreased concentration of plasma homocysteine was associated with increments of blood concentrations of both folate (β = -1.680, P = 0.004) and betaine (β = -1.421, P = 0.020) after 12 weeks of supplementation.

CONCLUSIONS

Daily supplementation with low-dose B vitamins plus betaine for 12 weeks effectively decreased plasma homocysteine concentrations in Chinese adults with hyperhomocysteinemia.

TRIAL REGISTRATION

This trial was registered at clinicaltrials.gov as NCT03720249 on October 25, 2018. Website: https://clinicaltrials.gov/ct2/show/NCT03720249 .

Association of serum homocysteine and folic acid levels with coagulation functions of cancer patients with venous thromboembolism

Venous thromboembolism (VTE) is a common coagulative dysfunctional complication of cancer patients. The present study aimed to determine the association and diagnostic values of serum homocysteine (Hcy) and folic acid levels with VTE in cancer patients. We enrolled 700 cancer patients and 100 healthy subjects in our study. All cancer patients, with or without VTE, underwent measurement of serum Hcy and folic acid levels and coagulative markers including D-Dimer, factor VIII, fibrinogen and tissue plasminogen activator. The diagnostic values of Hcy and folic acid were assessed by receiver operative characteristic (ROC) analysis. Correlations between Hcy and folic acid and coagulative factors were determined. Among the 700 patients with malignant tumors recruited in our study, a total of 89 patients had VTE combined within three months, and 611 patients did not have VTE. Cancer patients with VTE had significantly higher levels of Hcy and significantly lower levels of folic acid in serum. Both Hcy and folic acid in serum demonstrated high sensitivity and specificity in diagnosing VTE in cancer patients and showed strong correlations to coagulative markers. Hcy and folic acid, which have strong correlations to coagulative markers, are potential novel serum markers for stratifying VTE risk in cancer patients.

Using the optimal method-explained variance weighted genetic risk score to predict the efficacy of folic acid therapy to hyperhomocysteinemia

BACKGROUND

Genetic risk score (GRS) is a useful way to explore genetic architectures and the relationships of complex diseases. Several studies had revealed many single nucleotide polymorphisms (SNPs) associated with the efficacy of folic acid treatment to hyperhomocysteinemia (HHcy).

METHODS

We aimed to construct and screen out the optimal predictive model based on four GRSs and traditional risk factors. Four GRSs enrolled four SNPs (MTHFR rs1801131, MTHFR rs1801133, MTRR rs1801394, BHMT rs3733890) were presented as follows: (a) simple count genetic risk score (SC-GRS), (b) direct logistic regression genetic risk score (DL-GRS), (c) polygenic genetic risk score (PG-GRS), and (d) explained variance weighted genetic risk score (EV-GRS). We performed a prospective cohort study including 638 HHcy patients. Then we evaluated the associations of four GRSs with folic acid's efficacy and the performance of four GRSs.

RESULTS

Four GRSs were independently associated with efficacy of treatment (p < 0.05). When combining GRSs with traditional risk factors, the AUC of the four models were all above 0.900 in the training set (Tradition + SC-GRS: 0.909, Tradition + DL-GRS: 0.909, Tradition + PG-GRS: 0.904, Tradition + EV-GRS: 0.910). And EV-GRS got the highest AUC. When evaluating the models in the testing set, we got the same conclusion that EV-GRS was optimal among four GRSs with the highest AUC (0.878) and the highest increase of AUC (0.008).

CONCLUSION

A more precise predictive model combing the optimal GRS with traditional risk factors was constructed to predict the efficacy of folic acid therapy to HHcy.

Insufficient S-Sulfhydration of Methylenetetrahydrofolate Reductase Contributes to the Progress of Hyperhomocysteinemia

Aims: Hyperhomocysteinemia (HHcy) has been considered as a risk factor for cardiovascular disease, Alzheimer's disease, nonalcoholic fatty liver, and many other pathological conditions. Vitamin B6, Vitamin B12, and folate have been used to treat HHcy in clinics. However, at present, clinical therapies of HHcy display unsatisfactory effects. Here, we would like to explore a new mechanism involved in homocysteine (Hcy) metabolic disorders and a novel target for HHcy treatment. The key enzymes involved in Hcy metabolism deserve more insightful investigation. Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme regulating the intracellular Hcy metabolism. Until now, the effect of post-translational modification on the bioactivity of MTHFR still remains unclear. This study aimed at exploring the relationship between MTHFR S-sulfhydration and its bioactivity, and at identifying the contribution of an elevated Hcy level on MTHFR bioactivity. Results: By both in vivo and in vitro studies, we observed the following results: (i) The bioactivity of MTHFR was positively associated with its S-sulfhydration level; (ii) MTHFR was modified at Cys32, Cys130, Cys131, Cys193, and Cys306 by S-sulfhydration under physiological conditions; (iii) Hydrogen sulfide (H₂S) deficiency caused the decrease of MTHFR S-sulfhydration level and bioactivity in HHcy, which resulted in further aggravation of HHcy; and (iv) H₂S donors reversed the decreased bioactivity of MTHFR in HHcy, thus reducing the excessive Hcy level. Innovation and Conclusion: Our study suggested that H₂S could improve MTHFR bioactivity by S-sulfhydration, which might provide a candidate therapeutic strategy for HHcy. Antioxid. Redox Signal. 36, 1-14.

Blood and CSF Homocysteine Levels in Alzheimer's Disease: A Meta-Analysis and Meta-Regression of Case-Control Studies

OBJECTIVE

Hyperhomocysteinemia (HHcy), as an important risk factor for Alzheimer's disease (AD), would aggravate cognitive dysfunction. This study aimed to investigate whether and to what degree the homocysteine (Hcy) levels in blood and cerebrospinal fluid (CSF) were elevated in AD patients compared with healthy controls and to explore the factors related to the elevated Hcy levels in AD patients.

METHODS

PubMed and Embase databases were searched to identify eligible studies, and study quality was evaluated using the Newcastle-Ottawa Quality Assessment Scale. Ratio of mean (RoM) Hcy concentrations was used as a measure of fold-change between AD patients and healthy control subjects.

RESULTS

We identified 35 eligible studies, consisting a total of 2172 patients with AD and 2289 healthy controls. The pooled results showed that patients with AD had a significantly higher blood level of Hcy (RoM, 1.32; 95% CI, 1.25-1.40; p<0.001) than controls did, with large heterogeneity across studies (I²=81.4%, p<0.001). Hcy level in CSF did not differ significantly between patients with AD than controls (RoM, 1.12; 95% CI, 0.90-1.39, p=0.293; I²=69.4%, p=0.02). A random effects meta-regression analysis revealed that there was an inverse correlation between the blood levels of Hcy and folate (p=0.006). There was no link found between the blood levels of vitamin B_12, or the Mini-Mental Status Examination scores reflecting the degree of cognitive impairment, and blood levels of Hcy.

CONCLUSION

Regardless of dementia severity, there is an approximate one-third increase in blood Hcy in AD patients, which is robustly associated with a decreased level of blood folate in AD, but not with that of blood vitamin B₁₂ nor the degree of dementia. Future investigation on the cause-and-effect link between Hcy and folate is warranted to clarify this issue.

Combining genetic risk score with artificial neural network to predict the efficacy of folic acid therapy to hyperhomocysteinemia

Artificial neural network (ANN) is the main tool to dig data and was inspired by the human brain and nervous system. Several studies clarified its application in medicine. However, none has applied ANN to predict the efficacy of folic acid treatment to Hyperhomocysteinemia (HHcy). The efficacy has been proved to associate with both genetic and environmental factors while previous studies just focused on the latter one. The explained variance genetic risk score (EV-GRS) had better power and could represent the effect of genetic architectures. Our aim was to add EV-GRS into environmental factors to establish ANN to predict the efficacy of folic acid therapy to HHcy. We performed the prospective cohort research enrolling 638 HHcy patients. The multilayer perception algorithm was applied to construct ANN. To evaluate the effect of ANN, we also established logistic regression (LR) model to compare with ANN. According to our results, EV-GRS was statistically associated with the efficacy no matter analyzed as a continuous variable (OR = 3.301, 95%CI 1.954-5.576, P < 0.001) or category variable (OR = 3.870, 95%CI 2.092-7.159, P < 0.001). In our ANN model, the accuracy was 84.78%, the Youden's index was 0.7073 and the AUC was 0.938. These indexes above indicated higher power. When compared with LR, the AUC, accuracy, and Youden's index of the ANN model (84.78%, 0.938, 0.7073) were all slightly higher than the LR model (83.33% 0.910, 0.6687). Therefore, clinical application of the ANN model may be able to better predict the folic acid efficacy to HHcy than the traditional LR model. When testing two models in the validation set, we got the same conclusion. This study appears to be the first one to establish the ANN model which added EV-GRS into environmental factors to predict the efficacy of folic acid to HHcy. This model would be able to offer clinicians a new method to make decisions and individual therapeutic plans.

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

Background

Hyperhomocysteinemia (HHcy) is associated with various health problems, but less is known about the gender differences in risk factors for high plasma homocysteine (Hcy) levels.

Methods

In 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.

Results

Males 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.

Conclusions

Gender 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.

Diabetic Retinopathy: Mitochondria Caught in a Muddle of Homocysteine

Diabetic retinopathy is one of the most feared complications of diabetes. In addition to the severity of hyperglycemia, systemic factors also play an important role in its development. Another risk factor in the development of diabetic retinopathy is elevated levels of homocysteine, a non-protein amino acid, and hyperglycemia and homocysteine are shown to produce synergistic detrimental effects on the vasculature. Hyperhomocysteinemia is associated with increased oxidative stress, and in the pathogenesis of diabetic retinopathy, oxidative stress-mitochondrial dysfunction precedes the development of histopathology characteristic of diabetic retinopathy. Furthermore, homocysteine biosynthesis from methionine forms S-adenosyl methionine (SAM), and SAM is a co-substrate of DNA methylation. In diabetes, DNA methylation machinery is activated, and mitochondrial DNA (mtDNA) and several genes associated with mitochondrial homeostasis undergo epigenetic modifications. Consequently, high homocysteine, by further affecting methylation of mtDNA and that of genes associated with mtDNA damage and biogenesis, does not give any break to the already damaged mitochondria, and the vicious cycle of free radicals continues. Thus, supplementation of sensible glycemic control with therapies targeting hyperhomocysteinemia could be valuable for diabetic patients to prevent/slow down the development of this sight-threatening disease.

Folic acid ameliorates homocysteine-induced angiogenesis and portosystemic collaterals in cirrhotic rats

INTRODUCTION AND OBJECTIVES

Liver cirrhosis is characterized by increased intrahepatic resistance, splanchnic vasodilation/angiogenesis, and formation of portosystemic collateral vessels. Collaterals can cause lethal complications such as gastroesophageal variceal hemorrhage. Homocysteine is linked to vascular dysfunction and angiogenesis and higher levels have been reported in cirrhotic patients. It is also known that folic acid supplementation reverses the effects of homocysteine. However, the treatment effect in cirrhosis has yet to be investigated.

MATERIAL AND METHODS

Liver cirrhosis was induced in Sprague-Dawley rats with common bile duct ligation (CBDL). The CBDL rats randomly received (1) vehicle; (2) dl-homocysteine thiolactone (1g/kg/day); (3) dl-homocysteine thiolactone plus folic acid (100mg/kg/day); or (4) folic acid. On the 29th day, hemodynamic parameters, liver and renal biochemistry, protein expressions of proangiogenic factors, mesenteric vascular density and portosystemic shunting were evaluated.

RESULTS

In the cirrhotic rats, homocysteine increased mesenteric vascular density and the severity of shunting. It also up-regulated the protein expressions of mesenteric vascular endothelial growth factor (VEGF) and phosphorylated-endothelial nitric oxide synthase (p-eNOS). These effects were reversed by folic acid treatment (P<0.05).

CONCLUSION

Folic acid ameliorated the adverse effects of homocysteine in the cirrhotic rats, which may be related to down-regulation of the VEGF-NO signaling pathway.

Identifying gene-environment interactions on the efficacy of folic acid therapy for hyperhomocysteinemia based on prediction model

Various genetic and environmental factors or their interactions may result in the failure of folic acid therapy for hyperhomocysteinemia (HHcy). We hypothesized that an optimal predictive model of gene-environment interactions could be constructed to predict the efficacy of folic acid therapy in HHcy. A prospective cohort study of 638 HHcy patients was performed. The patients were treated with oral folic acid (5 mg/d) for 90 days. We used conditional inference tree model to stratify the failure risk of folic acid therapy synthesizing information from a weighted genetic risk score (wGRS) and environmental exposures, simultaneously interpreting the gene-environment interaction network in predicting the efficacy of HHcy. We detected high-order interactions between medical history of stroke, coronary heart disease (CHD), wGRS, and baseline total homocysteine (tHcy) on the failure risk of folic acid therapy. The wGRS in fourth quartile had 3.73-fold increased failure risk of folic acid treatment (odds ratio = 3.73, 95% confidence interval: 1.47-9.45). Stroke was identified as the key discriminator among the variables examined. A total of 3.3% of participants in failure group were at the lowest failure risk of folic acid therapy (nonstroke, non-CHD, baseline tHcy ≤ 31.1 μmol/L, wGRS ≤ 1.05). Individuals with stroke but with wGRS > 1.05 were at the highest failure risk of folic acid therapy (91.0% of participants in failure group). Medical history of stroke, CHD, wGRS, and baseline tHcy were consistently identified as significant risk factors for the failure risk of folic acid therapy. The multiple interactions between genetic and environmental factors can be visually presented via the conditional inference tree model.

Effect of Moxibustion on Hyperhomocysteinemia and Oxidative Stress Induced by High-Methionine Diet

Objective

The aim of this study was to assess the effects of moxibustion on the animal model of oxidative stress and cardiovascular injury induced by high-methionine diet (2% methionine and 3.5% fat on the basis of ordinary maintenance feed) during 12 weeks.

Methods

53 mice were divided into four groups: mice in the Control group (n = 8), mice in the Met group (n = 8), mice in the Met group (n = 8), mice in the Met group (n = 8), mice in the Met group (

Results

Compared with the Met group, our results indicated that through moxibustion intervention, the content of serum Hcy and its intermediate metabolite SAH can be reduced to a certain extent, and SOD, HO-1, and ox-LDL can be increased.

Conclusion

This study showed moxibustion's ability to enhance the body's antioxidation and protect vascular endothelial function, thus playing an early role in the prevention and treatment of atherosclerosis.

Association between BHMT and CBS gene promoter methylation with the efficacy of folic acid therapy in patients with hyperhomocysteinemia

Both betaine homocysteine methyltransferase (BHMT) and cystathionine β-synthase (CBS) are major enzymes in the metabolism of plasma homocysteine (Hcy). Abnormal methylation levels of BHMT and CBS are positively associated with Hcy levels. The present study is performed to explore the association between the methylation levels in the promoter regions of the BHMT and CBS genes and the efficacy of folic acid therapy in patient with hyperhomocysteinemia (HHcy). A prospective cohort study recruiting HHcy (Hcy ≥ 15 μmol/L) patients was performed. The subjects were treated with oral folic acid (5 mg/d) for 90 days, and the patients were divided into the success group (Hcy < 15 μmol/L) and the failure group (Hcy ≥ 15 μmol/L) according to their Hcy levels after treatment. In the logistic regression model with adjusted covariates, the patients with lower total methylation levels in the BHMT and CBS promoter regions exhibited 1.627-fold and 1.671-fold increased risk of treatment failure compared with higher methylation individuals, respectively. Similarly, subjects who had lower methylation levels (<methylation mean) in BHMT CpG1 had 1.792 times higher risks. Stratified analysis by sex found that lower CBS methylation levels were associated with a 2.128-fold increased risk for treatment failure in males with HHcy. Lower levels of BHMT or CBS promoter total methylation might be associated with increased the risk of treatment failure. These studies suggest that lower levels of BHMT and CBS methylation are all predictors of failure in folic acid therapy for HHcy. However, due to some limitations of this study, such as the small number of the loci tested, further large-scale studies are necessary to verify our observations.

Prediction model for the efficacy of folic acid therapy on hyperhomocysteinaemia based on genetic risk score methods

No risk assessment tools for the efficacy of folic acid treatment for hyperhomocysteinaemia (HHcy) have been developed. We aimed to use two common genetic risk score (GRS) methods to construct prediction models for the efficacy of folic acid therapy on HHcy, and the best gene-environment prediction model was screened out. A prospective cohort study enrolling 638 HHcy patients was performed. We used a logistic regression model to estimate the associations of two GRS methods with the efficacy. Performances were compared using area under the receiver operating characteristic curve (AUC). The simple count genetic risk score (SC-GRS) and weighted genetic risk score (wGRS) were found to be independently associated with the efficacy of folic acid treatment for HHcy. Using the SC-GRS, per risk allele increased with a 1·46-fold increased failure risk (P < 0·001) after adjustment for traditional risk factors, including age, sex, BMI, smoking, alcohol consumption, history of diabetes, history of hypertension, history of hyperlipidaemia, history of stroke and history of CHD. When used the wGRS, the association was strengthened (OR = 2·08, P < 0·001). Addition of the SC-GRS and wGRS to the traditional risk model significantly improved the predictive ability by AUC (0·859). A precise gene-environment predictive model with good performance was developed for predicting the treatment failure rate of folic acid therapy for HHcy.

Association between the BHMT gene rs3733890 polymorphism and the efficacy of oral folate therapy in patients with hyperhomocysteinemia

Oral folate is currently the most common treatment for hyperhomocysteinemia (HHcy), which seriously threatens human health, but its efficacy is unsatisfactory. Betaine-homocysteine methyltransferase (BHMT) is a key enzyme that regulates Hcy metabolism. We investigated the association between the BHMT rs3733890 and the efficacy of oral folate therapy for HHcy in the Chinese Han population and analysed the effects of gene-environmental interactions on the efficacy. Blood samples were collected from 1071 eligible patients at baseline, and these individuals received subsequent folate treatment for 90 days. A total of 638 patients included in the final analysis were grouped into the treatment success group or the treatment failure group based on posttreatment Hcy levels. Hcy concentrations were measured by fluorescence polarization immunoassay. Time-of-flight mass spectrometry (MassArray system) was used to assess the genotype of BHMT rs3733890. Stratified analyses based on additive models and generalized multifactor dimensionality reduction were used to explore gene-environmental interactions. The genotype distribution presented distinct differences in the two groups. The mutant genotype and allele had significantly increased risk of treatment failure (p < 0.05). Furthermore, synergistic effects of the BHMT rs3733890 polymorphism with environmental risk factors (smoking, drinking, past history) on the efficacy of therapy were also found. However, future, large well-designed studies, as well as mechanistic studies, are still needed to validate our findings.