Genetically based hypertension generated through interaction of mild hypoalphalipoproteinemia and mild hyperhomocysteinemia

Effects of four weeks lasting aerobic physical activity on cardiovascular biomarkers, oxidative stress and histomorphometric changes of heart and aorta in rats with experimentally induced hyperhomocysteinemia

The aim of this study was to examine the effects of hyperhomocysteinemia and aerobic physical activity on changes of cardiovascular biomarkers in sera, oxidative stress in cardiac tissue, and histomorphometric parameters of heart and aorta in rats. Experiments were conducted on male Wistar albino rats organized into four groups (n = 10, per group): C (control group): 0.9% NaCl 0.2 mL/day; H (homocysteine group): homocysteine 0.45 µmol/g b.w./day; CPA (control + physical activity group): 0.9% NaCl 0.2 mL/day and a program of physical activity on a treadmill; and HPA (homocysteine + physical activity group) homocysteine 0.45 µmol/g b.w./day and a program of physical activity on a treadmill. Substances were applied subcutaneously twice a day. Lipid peroxidation and relative activity of Mn-superoxide dismutase isoform were significantly higher in active hyperhomocysteinemic rats in comparison to sedentary animals. Atherosclerotic plaques were detected in aorta samples of active hyperhomocysteinemic rats and also, they had increased left ventricle wall and interventricular septum, and transverse diameter of cardiomyocytes compared to sedentary groups. Aerobic physical activity in the condition of hyperhomocysteinemia can lead to increased oxidative stress in cardiac tissue and changes in histomorphometric parameters of the heart and aorta, as well increased lipid parameters and cardiac damage biomarkers in sera of rats.

Serum apolipoprotein A1 rather than apolipoprotein B is associated with hypertension prevalence in Chinese people with coronary artery disease

OBJECTIVE

Studies on the association of apolipoprotein A1 (ApoA1) and apolipoprotein B (ApoB) with hypertension (HTN) prevalence in patients with coronary artery disease (CAD) are limited. This cross-sectional study aimed to investigate this association in Chinese people in Wuhan, China.

METHODS

Serum ApoA1 and ApoB levels were measured by immunoturbidimetry assay. Logistic regression analysis was used to estimate the associations of ApoA1 and ApoB level and ApoB/A1 ratio with HTN prevalence.

RESULTS

We included 5192 individuals (3060 men, mean age 61 years; 4412 HTN cases) in this study. After adjusting for covariates, serum ApoA1 but not ApoB level or ApoB/A1 ratio was inversely associated with HTN prevalence. HTN prevalence was reduced with the fifth versus first quintile of ApoA1 level [odds ratio = 0.78 (95% confidence interval 0.62-0.98)]. In stratified analyses based on sex, the probability of HTN with the fifth versus first ApoA1 level was 0.71 (0.53-0.96) for men. The probability of HTN with the fifth versus first quintile of ApoB/A1 ratio was 1.54 (1.11-2.13) after adjustment. With quintiles 2-5 versus of ApoB level, the probability of HTN did not differ in both men and women. On path analyses, the association of ApoA1 level and ApoB/A1 ratio with HTN was mediated by BMI (β coefficients: -0.179 to 0.133).

CONCLUSION

In general, high serum ApoA1 level may be associated with a reduced probability of HTN prevalence in patients with CAD in China, and this association may be mediated by BMI.

Dietary Erythrodiol Modifies Hepatic Transcriptome in Mice in a Sex and Dose-Dependent Way

Erythrodiol is a terpenic compound found in a large number of plants. To test the hypotheses that its long-term administration may influence hepatic transcriptome and this could be influenced by the presence of APOA1-containing high-density lipoproteins (HDL), Western diets containing 0.01% of erythrodiol (10 mg/kg dose) were provided to Apoe- and Apoa1-deficient mice. Hepatic RNA-sequencing was carried out in male Apoe-deficient mice fed purified Western diets differing in the erythrodiol content. The administration of this compound significantly up- regulated 68 and down-regulated 124 genes at the level of 2-fold change. These genes belonged to detoxification processes, protein metabolism and nucleic acid related metabolites. Gene expression changes of 21 selected transcripts were verified by RT-qPCR. Ccl19-ps2, Cyp2b10, Rbm14-rbm4, Sec61g, Tmem81, Prtn3, Amy2a5, Cyp2b9 and Mup1 showed significant changes by erythrodiol administration. When Cyp2b10, Dmbt1, Cyp2b13, Prtn3 and Cyp2b9 were analyzed in female Apoe-deficient mice, no change was observed. Likewise, no significant variation was observed in Apoa1- or in Apoe-deficient mice receiving doses ranging from 0.5 to 5 mg/kg erythrodiol. Our results give evidence that erythrodiol exerts a hepatic transcriptional role, but this is selective in terms of sex and requires a threshold dose. Furthermore, it requires an APOA1-containing HDL.

Single Nucleotide Polymorphisms in Key One-Carbon Metabolism Genes and Their Association with Blood Folate and Homocysteine Levels in a Chinese Population in Yunnan

OBJECTIVE

One-carbon metabolism (OCM) is essential for DNA synthesis and methylation. Single nucleotide polymorphisms (SNPs) within OCM genes may affect folic acid (FA) metabolism, disrupt homocysteine (Hcy) homeostasis, and increase the risk of disease. This study investigated the relationship between SNPs in key OCM genes and their association with blood FA and Hcy levels in a healthy population in Yunnan, China.

METHODS

Six SNPs within five key OCM genes (MTHFR C677T, MTHFR A1298C, MS A2756G, MTRR A66G, CBS T833C, and SHMT C1420T) were genotyped in 300 healthy volunteers (148 males and 152 females) using polymerase chain reaction/restriction fragment length polymorphism. Blood folate [serum FA (SFA) and red blood cell folate (RBC FA)] and Hcy levels were determined by chemiluminescence immunoassays and enzymatic assays.

RESULTS

Subjects with the MTHFR 677TT genotype had significantly higher Hcy levels and RBC FA concentrations compared with those harboring the MTHFR 677CC/CT genotypes (p < 0.01). Both Hcy and blood FA concentrations were also increased in subjects with MS 2756AA, as well as those within CBS 833TT, when compared with those with MS 2756AG/GG (p < 0.05) and CBS 833TC/CC (p < 0.05) genotypes, respectively. Subjects harboring the combined genotype of MTHFR 677TT and MS 2756AA had a higher Hcy concentration than those carrying other MTHFR and MS combinations (p = 0.002). Similarly, subjects harboring the combination of CBS 833TT with MTHFR 677TT had higher Hcy concentrations than those harboring other CBS and MTHFR combinations (p = 0.011).

CONCLUSIONS

The genotypes involving the MTHFR C677T, MS A2756G, and CBS T833C polymorphisms, including combinations of these genotypes, were the most important factors associated with blood FA and Hcy levels of the investigated SNPs in the OCM genes.

Correlation between cystathionine β-synthase T883C genetic polymorphism and primary hypertension

The present study aimed to investigate the correlation between cystathionine β-synthase (CBS) T833C polymorphisms and primary hypertension. A case-control study was conducted by genotyping the representative variation in 545 hypertensive individuals (aged 49.23±7.56 years) and 500 normotensive individuals (aged 49.90±10.01 years). The T833C genetic polymorphisms of the CBS enzyme were detected in all subjects by amplification refractory mutation system polymerase chain reaction (PCR) analysis. The CBS T833C polymorphism was successfully genotyped in the general population with a sample size of 1,045 (545+500) individuals. The genotypic and allelic frequency distributions of the CBS T833C polymorphism were not significantly different between the hypertensive and normotensive groups (P>0.05). The CC genotype was significantly different (P<0.05) from the CT and TT genotypes in terms of body mass index (BMI), and the levels of triglycerides (TG) and homocysteine (Hcy). Multiple logistic regression analysis revealed that BMI, total cholesterol (TC) level, smoking, plasma Hcy level and a family history of hypertension were the independent risk factors for hypertension in the population studied. The results indicate that the level of plasma Hcy was a risk factor for hypertension in the population studied. However, the mutation of the CBS T833C gene was not concluded to be an important hereditary factor for influencing the level of plasma Hcy.

Vascular complications of cystathionine β-synthase deficiency: future directions for homocysteine-to-hydrogen sulfide research

Homocysteine (Hcy), a cardiovascular and neurovascular disease risk factor, is converted to hydrogen sulfide (H(2)S) through the transsulfuration pathway. H(2)S has attracted considerable attention in recent years for many positive effects on vascular health and homeostasis. Cystathionine β-synthase (CBS) is the first, and rate-limiting, enzyme in the transsulfuration pathway. Mutations in the CBS gene decrease enzymatic activity, which increases the plasma Hcy concentration, a condition called hyperhomocysteinemia (HHcy). Animal models of CBS deficiency have provided invaluable insights into the pathological effects of transsulfuration impairment and of both mild and severe HHcy. However, studies have also highlighted the complexity of HHcy and the need to explore the specific details of Hcy metabolism in addition to Hcy levels per se. There has been a relative paucity of work addressing the dysfunctional H(2)S production in CBS deficiency that may contribute to, or even create, HHcy-associated pathologies. Experiments using CBS knockout mice, both homozygous (-/-) and heterozygous (+/-), have provided 15 years of new knowledge and are the focus of this review. These murine models present the opportunity to study a specific mechanism for HHcy that matches one of the etiologies in many human patients. Therefore, the goal of this review was to integrate and highlight the critical information gained thus far from models of CBS deficiency and draw attention to critical gaps in knowledge, with particular emphasis on the modulation of H(2)S metabolism. We include findings from human and animal studies to identify important opportunities for future investigation that should be aimed at generating new basic and clinical understanding of the role of CBS and transsulfuration in cardiovascular and neurovascular disease.

Simvastatin reverses the hypertension of heterozygous mice lacking cystathionine beta-synthase and apolipoprotein A-I

Double heterozygous mice lacking Apoa1 and Cbs genes show mild hyperhomocysteinemia in combination with hypoalphalipoproteinemia. This situation leads to a moderate hypertension associated with a dysregulation in nitric oxide metabolism. The aim of this study was to investigate the potential beneficial effects of statin treatment in these mice. After 4 weeks of simvastatin administration, plasma parameters; apolipoproteins A-I, A-II and A-IV; lipid profile; and blood pressure were assessed, Western blotting was performed in the aorta of these mice to measure endothelial nitric oxide synthase and caveolin-1 content. The high blood pressure level present in the double heterozygous group was corrected down to that of the wild-type group after simvastatin treatment (124+/-7.7 vs. 109+/-11.2 mmHg, p<0.01). Concomitant with this effect, an increase in nitric oxide levels was observed in these double heterozygous mice receiving simvastatin treatment probably mediated in part by a decrease in caveolin-1 levels. Blood pressure changes appeared to be independent of the arylesterase activity of paraoxonase or the lipid content. Another remarkable result was the significant increase in apoA-IV content in animals receiving simvastatin, an effect considered to be protective for the endothelium. In conclusion, the results of this study demonstrate that the use of simvastatin can improve blood pressure control in mice with elevated homocysteinemia and low levels of apoA-I, and this effect is mediated by mechanisms independent of plasma lipids and related to nitric oxide levels.