Predicting Hyperhomocysteinemia by Methylenetetrahydrofolate Reductase C677T Polymorphism in Chinese Patients With Hypertension

Genetic and epigenetic factors of arterial hypertension: a bibliometric- and in-silico-based analyses

Introduction: Arterial hypertension (AH) is a pervasive global health concern with multifaceted origins encompassing both genetic and environmental components. Previous research has firmly established the association between AH and diverse genetic factors. Consequently, scientists have conducted extensive genetic investigations in recent years to unravel the intricate pathophysiology of AH. Methods: In this study, we conducted a comprehensive bibliometric analysis employing VOSviewer software to identify the most noteworthy genetic factors that have been the focal point of numerous investigations within the AH field in recent years. Our analysis revealed genes and microRNAs intricately linked to AH, underscoring their pivotal roles in this condition. Additionally, we performed molecular docking analyses to ascertain microRNAs with the highest binding affinity to these identified genes. Furthermore, we constructed a network to elucidate the in-silico-based functional interactions between the identified microRNAs and genes, shedding light on their potential roles in AH pathogenesis. Results: Notably, this pioneering in silico examination of genetic factors associated with AH promises novel insights into our understanding of this complex condition. Our findings prominently highlight miR-7110-5p, miR-7110-3p, miR-663, miR-328-3p, and miR-140-5p as microRNAs exhibiting a remarkable affinity for target genes. These microRNAs hold promise as valuable diagnostic and therapeutic factors, offering new avenues for the diagnosis and treatment of AH in the foreseeable future. Conclusion: In summary, this research underscores the critical importance of genetic factors in AH and, through in silico analyses, identifies specific microRNAs with significant potential for further investigation and clinical applications in AH management.

Ablation of the gut microbiota alleviates high-methionine diet-induced hyperhomocysteinemia and glucose intolerance in mice

A high-methionine (HM) diet leads to hyperhomocysteinemia (HHcy), while gastrointestinal tissue is an important site of net homocysteine (Hcy) production. However, the role of the gut microbiota in host HHcy remains obscure. This study aimed to determine whether gut microbiota ablation could alleviate host HHcy and glucose intolerance and reveal the underlying mechanism. The results showed that the HM diet-induced HHcy and glucose intolerance in mice, while antibiotic administration decreased the plasma level of Hcy and reversed glucose intolerance. HM diet increased intestinal epithelial homocysteine levels, while antibiotic treatment decreased intestinal epithelial homocysteine levels under the HM diet. Gut microbiota depletion had no effect on the gene expression and enzyme activity of CBS and BHMT in the livers of HM diet-fed mice. The HM diet altered the composition of the gut microbiota with marked increases in the abundances of Faecalibaculum and Dubosiella, which were also positively correlated with plasma Hcy concentrations. An in-depth analysis of the bacterial cysteine and methionine metabolism pathways showed that the abundances of two homocysteine biosynthesis-related KEGG orthologies (KOs) were markedly increased in the gut microbiota in HM diet-fed mice. Hcy was detected from Dubosiella newyorkensis-cultured supernatant by liquid chromatography-tandem mass spectrometry (LC‒MS) analysis. In conclusion, these findings suggested that the HM diet-induced HHcy and glucose intolerance in mice, by reshaping the composition of the gut microbiota, which might produce and secrete Hcy.

Tetrahydroxystilbene glucoside attenuated homocysteine-upregulated endothelin receptors in vascular smooth muscle cells via the ERK1 /2 /NF-κB signaling pathway

2,3,5,4'-Tetrahydrostilbene-2-o-β-d-glucoside (TSG) is the main active component of Polygonum multiflorum Thunb. It has effects on hypertension. However, the mechanism is unclear. Current research is devoted to exploring the mechanism of TSG improving HHcy-induced hypertension. The mice received a subcutaneous injection of Hcy in the presence or absence of TSG for 4 weeks. Blood pressure (BP) was measured using a noninvasive tail-cuff plethysmography method. Levels of plasma Hcy and endothelin-1 were measured using ELISA. Rat SMA without endothelium was cultured in a serum-free medium in the presence or absence of TSG with or without Hcy. The contractile response to sarafotoxin 6c or endothein-1 was studied using a sensitive myography. The levels of protein were detected using Western blotting. The results showed that TSG lowered HHcy-elevated BP and decreased levels of plasma Hcy and endothelin-1 in mice. Furthermore, the results showed that TSG inhibited Hcy-upregulated ET receptor expression and ET receptor-mediated contractile responses as well as the levels of p-ERK_1/2 and p-p65 in SMA. In vivo results further validate the in vitro results. In conclusion, TSG can decrease the levels of plasma Hcy and ET-1 and downregulate Hcy-upregulated ET receptors in VSMCs by inhibiting the ERK_1/2 /NF-κB/ET_B2 pathway to lower the BP.

Methylenetetrahydrofolate Reductase Polymorphism (rs1801133) and the Risk of Hypertension among African Populations: A Narrative Synthesis of Literature

In this review, we have gathered and analyzed the available genetic evidence on the association between the methylenetetrahydrofolate reductase gene (MTHFR), rs1801133 and the risk of Hypertension (HTN) in African populations, which was further compared to the global data evidence. This review was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol and Human Genome Epidemiology Network (HuGENet) guidelines. Literature was retrieved through major search databases, including PubMed, Scopus, Web of Science, and African Journal Online. We identified 64 potential studies, of which 4 studies were from the African continent and 60 studies were reported globally. Among the studies conducted in Africa, only two (n = 2) reported a significant association between the MTHFR (rs1801133) and the risk of developing HTN. Only one (n = 1) study population was purely composed of black Africans, while others were of other ethnicities. Among studies conducted in other continents (n = 60), forty-seven (n = 47) studies reported a positive association between MTHFR (rs1801133) and the risk of developing HTN, whereas the remaining studies (n = 14) did not show a significant association. Available literature suggests an apparent association between rs1801133 and HTN in global regions; however, such information is still scarce in Africa, especially in the black African population.

Effects of individualized administration of folic acid on prothrombotic state and vascular endothelial function with H-type hypertension: A double-blinded, randomized clinical cohort study

BACKGROUND

Hypertension and hyperhomocysteinemia (HHcy) have long been associated with adverse cardiovascular and cerebrovascular health outcomes. This study evaluated the effect of individualized administration of folic acid (FA) on homocysteine (Hcy) levels, prothrombotic state, and blood pressure (BP) in patients with H-type hypertension (combination of HHcy and hypertension).

METHODS

In this double-blinded, randomized clinical cohort study, 126 patients with H-type hypertension who were treated at our hospital were randomly divided into treatment and control groups (n = 55 each). The control group was treated with oral levamlodipine besylate tablets 2.5 mg and placebo, once a day (in the morning). The treatment group was first treated with oral levamlodipine besylate 2.5 mg and FA tablets 0.8 mg, once a day (in the morning), for 12 weeks. Then, in a second 12-week phase, the FA dose was adjusted using the methylene tetrahydrofolate reductase C677 polymorphism genotype. The levels of Hcy and coagulation factors, prothrombotic state parameters, BP, and adverse drug reactions were compared between the 2 groups.

RESULTS

Pretreatment general patient characteristics, including Hcy levels, were similar between the 2 groups (P > .05). BP and prothrombotic status did not differ before and after the first phase of treatment (P > .05). However, Hcy and endothelin-1 (ET-1) levels decreased, while nitric oxide levels increased significantly in the intervention group (P < .05). In the second phase, after 3 months' treatment with an FA dose adjusted according to methylene tetrahydrofolate reductase C677T genotype, the Hcy and ET-1/NO levels were significantly decreased in the intervention group and were lower than those after the first treatment phase and lower than in the control group (P < .01). BP, D-dimer levels, and fibrinogen scores were significantly lower after the second treatment phase (P < .01). There was no significant difference in the incidence of adverse drug reactions between the 2 groups (P > .05).

CONCLUSIONS

Individualized administration of FA tablets can effectively reduce BP, and Hcy and coagulation factor levels, and significantly improve prothrombotic status in patients with H-type hypertension.

Association Between MTHFR Polymorphisms and the Risk of Essential Hypertension: An Updated Meta-analysis

BACKGROUND

Since the 1990s, there have been a lot of research on single-nucleotide polymorphism (SNP) and different diseases, including many studies on 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphism and essential hypertension (EH). Nevertheless, their conclusions were controversial. So far, six previous meta-analyses discussed the internal relationship between the MTHFR polymorphism and EH, respectively. However, they did not evaluate the credibility of the positive associations. To build on previous meta-analyses, we updated the literature by including previously included papers as well as nine new articles, improved the inclusion criteria by also considering the quality of the papers, and applied new statistical techniques to assess the observed associations.

OBJECTIVES

This study aims to explore the degree of risk correlation between two MTHFR polymorphisms and EH.

METHODS

PubMed, EMBASE, the Cochrane Library, CNKI, and Wan Fang electronic databases were searched to identify relevant studies. We evaluated the relation between the MTHFR C677T (rs1801133) and A1298C (rs1801131) polymorphisms and EH by calculating the odds ratios (OR) as well as 95% confidence intervals (CI). Here we used subgroup analysis, sensitivity analysis, cumulative meta-analysis, assessment of publication bias, meta-regression meta, False-positive report probability (FPRP), Bayesian false discovery probability (BFDP), and Venice criterion.

RESULTS

Overall, harboring the variant of MTHFR C677T was associated with an increased risk of EH in the overall populations, East Asians, Southeast Asians, South Asians, Caucasians/Europeans, and Africans. After the sensitivity analysis, positive results were found only in the overall population (TT vs. CC: OR = 1.14, 95% CI: 1.00-1.30, P _h = 0.032, I ² = 39.8%; TT + TC vs. CC: OR = 1.15, 95% CI: 1.01-1.29, P _h = 0.040, I ² = 38.1%; T vs. C: OR = 1.14, 95% CI: 1.04-1.25, P _h = 0.005, I ² = 50.2%) and Asian population (TC vs. CC: OR = 1.14, 95% CI: 1.01-1.28, P _h = 0.265, I ² = 16.8%; TT + TC vs. CC: OR = 1.17, 95% CI: 1.04-1.30, P _h = 0.105, I ² = 32.9%; T vs. C: OR = 1.10, 95% CI: 1.02-1.19, P _h = 0.018, I ² = 48.6%). However, after further statistical assessment by FPRP, BFDP, and Venice criteria, the positive associations reported here could be deemed to be false-positives and present only weak evidence for a causal relationship. In addition, when we performed pooled analysis and sensitivity analysis on MTHFR A1298C; all the results were negative.

CONCLUSION

The positive relationships between MTHFR C677T and A1298C polymorphisms with the susceptibility to present with hypertension were not robust enough to withstand statistical interrogation by FPRP, BFDP, and Venice criteria. Therefore, these SNPs are probably not important in EH etiology.

Evidence on the causal link between homocysteine and hypertension from a meta-analysis of 40 173 individuals implementing Mendelian randomization

Numerous researchers have investigated the associations among methylenetetrahydrofolate reductase gene (MTHFR) C677T polymorphism, homocysteine (Hcy) concentration, and hypertension. However, the results are controversial. Thus, a meta-analysis implementing Mendelian randomization approach was conducted to examine the hypothesis that elevated Hcy concentration plausibly contributes to increased risk of hypertension. Based on several inclusion and exclusion criteria, eligible studies were selected to explore the correlation between MTHFR C677T and hypertension risk, MTHFR C677T and Hcy concentration in hypertension, and Hcy concentration and hypertension, and they were evaluated by odds ratios (ORs), effect size (ES), and standard mean difference with their corresponding 95% confidence intervals (95% CIs), respectively. Moreover, Mendelian randomization was implemented to evaluate the relationship between Hcy and hypertension. Consequently, 14 378 cases and 25 795 controls were involved in this study and the results showed that MTHFR C677T led to an elevated risk of hypertension (for T vs C: OR = 1.27, 95% CI = 1.17-1.37; for TT vs CC: OR = 1.53, 95% CI = 1.30-1.79). Additionally, in hypertensive subjects, the pooled Hcy concentration in individuals of TT genotype was 7.74 μmol/L (95% CI: 5.25-10.23) greater than that in individuals of CC genotype. Moreover, the pooled Hcy concentration in hypertensive was 0.69 μmol/L (95% CI: 0.50-0.87) greater than that in controls. The estimated causal OR associated with hypertension was 1.32 for 5 μmol/L Hcy increment. Via MTHFR C677T polymorphism, the findings in the present study demonstrated that there exists evidence on causal link between Hcy concentration and the risk of hypertension.

Associations of homocysteine status and homocysteine metabolism enzyme polymorphisms with hypertension and dyslipidemia in a Chinese hypertensive population

Background: Hypertension (HTN), dyslipidemia and hyperhomocysteinemia (HHcy) are risk factors for cardiovascular disease (CVD).Methods: Hypertensive Chinese subjects (n = 228) were enrolled. MTHFR C667T, MTHFR A1298C, MTR A2756G, and MTRR A66G genotypes were determined. Unconditional logistic regression was performed to determine the associations of serum Hcy status and genotypes with HTN and dyslipidemia.Results: The mean age of hypertensive adults was 65.53 ± 9.94 years, including 88 (38.6%) men and 140 (61.4%) women. Patients with MTHFR 667TT and MTRR GG carriers showed higher serum Hcy levels (P = 0.019 and 0.018, respectively), which is associated with higher serum triacylglycerols (TAG) and total cholesterol (TC) levels (P = 0.014 and 0.044, respectively) and a higher risk for hypertriglyceridemia (OR = 1.889, 95% CI: 1.105-3.229, P = 0.020). Compared with low Hcy and MTRR 66AA, those with high Hcy and 66AA or 66AG+GG showed higher odd\s of hypertriglyceridemia (MTRR 66AA+ high Hcy: OR: 2.692, 95% CI: 1.189-6.096, Pcombined = 0.018; MTRR 66AG/GG+ high Hcy: OR: 3.433, 95% CI: 1.517-7.772, Pcombined = 0.003, respectively). Patients with high Hcy and MTHFR 667CC, as well as those with low Hcy and 667CT+TT, showed lower odds of uncontrolled SBP (MTHFR 667CC+ high Hcy: OR: 0.338, 95% CI: 0.115-0.996, Pcombined = 0.049; MTHFR 667CT/TT+ low Hcy: OR: 0.421, 95% CI: 0.193-0.921, Pcombined = 0.030) compared to patients with low Hcy and MTHFR 667CC.Conclusions: Serum Hcy status and Hcy metabolism gene polymorphisms (MTHFR C667T and MTRR A66G) may have synergistic effects on the prevalence of HTN and dyslipidemia.

Methylenetetrahydrofolate Reductase Gene Polymorphism (C677T) as a Risk Factor for Arterial Thrombosis in Georgian Patients

Methylenetetrahydrofolate reductase (MTHFR) gene polymorphism (C677T)] is a well-recognized genetic risk factor for venous thrombosis; however, its association with arterial thrombosis is still under debate. Herein, we evaluated the prevalence of MTHFR C677T polymorphism in Georgian patients in comparison with healthy individuals and its association with arterial thrombosis. We enrolled 214 participants: 101 with arterial thrombosis (71.3% males; mean age: 66.3 ± 12.1 years) and 113 controls (67.3% males; mean age: 56.6 ± 11.3 years). Genomic DNA was extracted from dry blood spot on Whatman filter paper. Polymerase chain reaction was performed to determine MTHFR C677T polymorphism. Frequency of C677T allele polymorphism in controls was 21.2%, which corresponded to heterozygous and homozygous stage frequencies of 35.4% and 3.5%, respectively. In patient group, an allelic frequency of 33.2% was found, which corresponded to the presence of 48.5% of heterozygous and 8.9% of homozygous individuals. Comparing the frequency of mutated alleles between the 2 groups, a significantly high frequency of mutated alleles was found in patient group (P < .05). In conclusion, high frequency of MTHFR C677T polymorphism found in arterial thrombosis patient group suggests that this polymorphism might increase the risk of arterial thrombosis in Georgian patients.

Hyperhomocysteinaemia and vascular injury: advances in mechanisms and drug targets

Homocysteine is a sulphur-containing non-proteinogenic amino acid. Hyperhomocysteinaemia (HHcy), the pathogenic elevation of plasma homocysteine as a result of an imbalance of its metabolism, is an independent risk factor for various vascular diseases, such as atherosclerosis, hypertension, vascular calcification and aneurysm. Treatments aimed at lowering plasma homocysteine via dietary supplementation with folic acids and vitamin B are more effective in preventing vascular disease where the population has a normally low folate consumption than in areas with higher dietary folate. To date, the mechanisms of HHcy-induced vascular injury are not fully understood. HHcy increases oxidative stress and its downstream signalling pathways, resulting in vascular inflammation. HHcy also causes vascular injury via endoplasmic reticulum stress. Moreover, HHcy up-regulates pathogenic genes and down-regulates protective genes via DNA demethylation and methylation respectively. Homocysteinylation of proteins induced by homocysteine also contributes to vascular injury by modulating intracellular redox state and altering protein function. Furthermore, HHcy-induced vascular injury leads to neuronal damage and disease. Also, an HHcy-activated sympathetic system and HHcy-injured adipose tissue also cause vascular injury, thus demonstrating the interactions between the organs injured by HHcy. Here, we have summarized the recent developments in the mechanisms of HHcy-induced vascular injury, which are further considered as potential therapeutic targets in this condition.

LINKED ARTICLES

This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Early Detection System of Vascular Disease and Its Application Prospect

Markers of imaging, structure, and function reflecting vascular damage, integrating a long time accumulation effect of traditional and unrecognized cardiovascular risk factors, can be regarded as surrogate endpoints of target organ damage before the occurrence of clinical events. Prevention of cardiovascular disease requires risk stratification and treatment of traditional risk factors, such as smoking, hypertension, hyperlipidemia, and diabetes. However, traditional risk stratification is not sufficient to provide accurate assessment of future cardiovascular events. Therefore, vascular injury related parameters obtained by ultrasound or other noninvasive devices, as a surrogate parameter of subclinical cardiovascular disease, can improve cardiovascular risk assessment and optimize the preventive treatment strategy. Thus, we will summarize the research progress and clinical application of early assessment technology of vascular diseases in the present review.