Interactions between the genes of vasodilatation pathways influence blood pressure and nitric oxide level in hypertension

Wet Cupping’s Effect on Nitric Oxide Levels in Hypertensive Patients

BACKGROUND: Wet cupping is a non-pharmacological therapy that has been shown to assist hypertensive patients with blood pressure reduction. However, the underlying mechanisms by which wet-cupping lowers blood pressure are currently unknown. More scientific investigation is necessary to explain the mechanism by which wet cupping lowers blood pressure, particularly the role of nitric oxide (NO). AIM: The study aimed to show the effect of wet cupping on NO levels in hypertensive patients. METHODS: A pre-experimental study using a single group pre-test and post-test design to monitor changes in blood NO levels and blood pressure in 45 hypertensive patients in Medan after 4 weeks of wet cupping therapy. The patients’ blood NO levels, as well as their systolic and diastolic blood pressures (SBP and DBP), were measured before and after 4 weeks of wet cupping. RESULTS: After 4 weeks of wet cupping, blood NO levels significantly increased (0.00704 mol/mL, p=0.039), while SBP and DBP levels significantly decreased (12.644 mmHg and 7.111 mmHg, respectively, p<0.001). However, there was no correlation between increased blood NO levels and reductions in SBP and DBP (p=0.468 and p=0.299, respectively). CONCLUSION: This study found that after 4 weeks of cupping therapy, the decrease in SBP and DBP was not accompanied by an increase in blood NO levels.

Targeted capture sequencing identifies genetic variations of GRK4 and RDH8 in Han Chinese with essential hypertension in Xinjiang

Essential hypertension is a common cardiovascular disease with complex etiology, closely related to genetic and environmental factors. The pathogenesis of hypertension involves alteration in vascular resistance caused by sympathetic nervous system (SNS) and renin angiotensin system (RAS). Susceptibility factors of hypertension vary with regions and ethnicities. In this study, we conducted target capture sequencing on 54 genes related to SNS and RAS derived from a collection of Han nationality, consisting of 151 hypertension patients and 65 normal subjects in Xinjiang, China. Six non-synonymous mutations related to hypertension were identified, including GRK4 rs1644731 and RDH8 rs1801058, Mutations are predicted to affect 3D conformation, force field, transmembrane domain and RNA secondary structure of corresponding genes. Based on protein interaction network and pathway enrichment, GRK4 is predicted to participate in hypertension by acting on dopaminergic synapse, together with interacting components. RDH8 is involved in vitamin A (retinol) metabolism and consequent biological processes related to hypertension. Thus, GRK4 and RDH8 may serve as susceptibility genes for hypertension. This finding provides new genetic evidence for elucidating risk factors of hypertension in Han nationality in Xinjiang, which in turn, enriches genetic resource bank of hypertension susceptibility genes.

Genomic Association of Single Nucleotide Polymorphisms with Blood Pressure Response to Hydrochlorothiazide among South African Adults with Hypertension

This study described single nucleotide polymorphisms (SNPs) in hydrochlorothiazide-associated genes and further assessed their correlation with blood pressure control among South African adults living with hypertension. A total of 291 participants belonging to the Nguni tribes of South Africa on treatment for hypertension were recruited. Nineteen SNPs in hydrochlorothiazide pharmacogenes were selected and genotyped using MassArray. Uncontrolled hypertension was defined as blood pressure ≥140/90 mmHg. The association between genotypes, alleles and blood pressure response to treatment was determined by conducting multivariate logistic regression model analysis. The majority of the study participants were female (73.19%), Xhosa (54.98%) and had blood pressure ≥140/90 mmHg (68.73%). Seventeen SNPs were observed among the Xhosa tribe, and two (rs2070744 and rs7297610) were detected among Swati and Zulu participants. Furthermore, alleles T of rs2107614 (AOR = 6.69; 95%CI 1.42–31.55; p = 0.016) and C of rs2776546 (AOR = 3.78; 95%CI 1.04–13.74; p = 0.043) were independently associated with uncontrolled hypertension, whilst rs2070744 TC (AOR = 38.76; 95%CI 5.54–270.76; p = 0.00023), CC (AOR = 10.44; 95%CI 2.16–50.29; p = 0.003) and allele T of rs7297610 (AOR = 1.86; 95%CI 1.09–3.14; p = 0.023) were significantly associated with uncontrolled hypertension among Zulu and Swati participants. We confirmed the presence of SNPs associated with hydrochlorothiazide, some of which were significantly associated with uncontrolled hypertension in the study sample. Findings open doors for further studies on personalized therapy for hypertension in the country.

Vascular homeostasis at high-altitude: role of genetic variants and transcription factors

High-altitude pulmonary edema occurs most frequently in non-acclimatized low landers on exposure to altitude ≥2500 m. High-altitude pulmonary edema is a complex condition that involves perturbation of signaling pathways in vasoconstrictors, vasodilators, anti-diuretics, and vascular growth factors. Genetic variations are instrumental in regulating these pathways and evidence is accumulating for a role of epigenetic modification in hypoxic responses. This review focuses on the crosstalk between high-altitude pulmonary edema-associated genetic variants and transcription factors, comparing high-altitude adapted and high-altitude pulmonary edema-afflicted subjects. This approach might ultimately yield biomarker information both to understand and to design therapies for high-altitude adaptation.

Blood Pressure in Andean Adults Living Permanently at Different Altitudes

Vinueza Veloz, Andrés Fernando, Aymaru Kailli Yaulema Riss, Chris I. De Zeeuw, Tannia Valeria Carpio Arias, and María Fernanda Vinueza Veloz. Blood pressure in Andean adults living permanently at different altitudes. High Alt Med Biol. 21:360-369, 2020. Aims: To estimate the association between blood pressure (BP) and chronic exposure to altitude in nonhypertensive Andean adults, while taking ethnicity into consideration. Materials and Methods: Sample included 10,041 nonhypertensive adults with indigenous or mixed ethnic background (the latter also referred to as mestizos), who permanently lived at different altitudes. BP was measured following international recommendations. Altitude was measured in meters above the sea level (masl) using a global positioning system. Data were analyzed through linear regression models with restricted cubic splines. Results: A significant nonlinear relation between altitude and systolic blood pressure (SBP) as well as diastolic blood pressure (DBP) was found (both p < 0.001). BP described a j-shaped curve, where the minimum was observed between 750 and 1250 masl, from where both SBP and DBP rose as altitude increased. These associations were independent from sex, age, index of economic wellbeing, body mass index, and years of education. Interestingly, at all altitudes indigenous people had lower SBP and DBP in comparison to mestizos (both p < 0.001). Conclusions: Living permanently at altitudes ≥750 masl is associated with higher SBP and DBP in Andean dwellers and this association is modulated by their ethnic background.

An Overview of Non-coding RNAs and Cardiovascular System

Cardiovascular disease management and timely diagnosis remain a major dilemma. Delineating molecular mechanisms of cardiovascular diseases is opening horizon in the field of molecular medicines and in the development of early diagnostic markers. Non-coding RNAs are the highly functional and vibrant nucleic acids and are known to be involved in the regulation of endothelial cells, vascular and smooth muscles cells, cardiac metabolism, ischemia, inflammation and many processes in cardiovascular system. This chapter is comprehensively focusing on the overview of the non-coding RNAs including their discovery, generation, classification and functional regulation. In addition, overview regarding different non-coding RNAs as long non-coding, siRNAs and miRNAs involvement in the cardiovascular diseases is also addressed. Detailed functional analysis of this vast group of highly regulatory molecules will be promising for shaping future drug discoveries.

Multicomponent Training Changes Blood Pressure and Redox Status in Older Women: Influence of β2 Adrenergic Receptor Haplotypes

The β2 adrenergic receptor (β2-AR) plays an important role in vascular smooth muscle. However, the interaction between Arg16Gly and Gln27Glu β2-AR polymorphisms, and exercise training has not yet been established. This study evaluated the influence of these β2-AR polymorphisms on body composition, aerobic capacity, blood pressure, lipid profile, nitric oxide, and redox status at baseline and in response to an exercise program in women aged 50-79 years. Genotype and haplotypes were analyzed in association with the previously mentioned variables before and after the multicomponent training (12 weeks, 2 sessions/week, 90 min/session, and exercise intensity between 13 and 15 on the Borg scale). Individuals who carry β2-AR Arg16Arg/Gln27Gln genotypes presented more improvements in blood pressure, body composition, aerobic capacity, and redox status in response to a multicomponent training program compared with individuals who do not carry this haplotype. In some years, the genetic profile may be used to predict which exercise program can induce more health benefits for each person.

Structural and functional alterations of nitric oxide synthase 3 due to missense variants associate with high-altitude pulmonary edema through dynamic study

The human endothelial nitric oxide synthase (NOS3) is 28 Kbp at 7q36.1 and encodes protein comprising of 1280 amino acids. Being a major source of nitric oxide, the enzyme is crucial to the vascular homeostasis and thereby to be an important pharmaceutical target. We hence have been investigating this molecule in a high-altitude disorder namely, high-altitude pulmonary edema (HAPE). We performed a genome-wide association study (GWAS) in a case-control design of sojourners that included healthy controls and HAPE patients (n = 200) each. Four NOS3 missense SNPs i.e. rs1799983 (E298D), rs3918232 (V827M), rs3918201 (R885M) and rs3918234 (Q982L), were associated significantly with HAPE (P-value < 0.05). Furthermore, extensive in silico analyses were performed to predict the detrimental effect of the four variant types and their three most relevant co-factors namely, heme, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) that are accountable for amendment of protein stability leading to structural de-construction. Subsequently, we validated the findings in a larger sample size of the two study groups. HAPE patients had a higher frequency of the four variants and significantly decreased levels of circulating nitric oxide (NO) (P-value < 0.001). The in silico and human subjects findings complement each other. This study explored the impact of HAPE-associated NOS3 variants with its protein structure stability and holds promise to be current and future drug targets.Communicated by Ramaswamy H. Sarma.

Genetics of Human Primary Hypertension: Focus on Hormonal Mechanisms

Increasingly, primary hypertension is being considered a syndrome and not a disease, with the individual causes (diseases) having a common sign-an elevated blood pressure. To determine these causes, genetic tools are increasingly employed. This review identified 62 proposed genes. However, only 21 of them met our inclusion criteria: (i) primary hypertension, (ii) two or more supporting cohorts from different publications or within a single publication or one supporting cohort with a confirmatory genetically modified animal study, and (iii) 600 or more subjects in the primary cohort; when including our exclusion criteria: (i) meta-analyses or reviews, (ii) secondary and monogenic hypertension, (iii) only hypertensive complications, (iv) genes related to blood pressure but not hypertension per se, (v) nonsupporting studies more common than supporting ones, and (vi) studies that did not perform a Bonferroni or similar multiassessment correction. These 21 genes were organized in a four-tiered structure: distant phenotype (hypertension); intermediate phenotype [salt-sensitive (18) or salt-resistant (0)]; subintermediate phenotypes under salt-sensitive hypertension [normal renin (4), low renin (8), and unclassified renin (6)]; and proximate phenotypes (specific genetically driven hypertensive subgroup). Many proximate hypertensive phenotypes had a substantial endocrine component. In conclusion, primary hypertension is a syndrome; many proposed genes are likely to be false positives; and deep phenotyping will be required to determine the utility of genetics in the treatment of hypertension. However, to date, the positive genes are associated with nearly 50% of primary hypertensives, suggesting that in the near term precise, mechanistically driven treatment and prevention strategies for the specific primary hypertension subgroups are feasible.

Effects of a Dietary Beetroot Juice Treatment on Systemic and Cerebral Haemodynamics- A Pilot Study

INTRODUCTION

Beetroot Juice (BJ) contains dietary nitrates that increase the blood Nitric Oxide (NO) level, decrease Blood Pressure (BP), increase athletic performance and improve cognitive functions but the mechanism remains unclear. Ultrasonographic measurement of middle cerebral artery blood flow velocity with computation of Cerebral Augmentation Index (CAIx) is a measure of the reflected flow signal, modulated by changes in cerebrovascular resistance and compliance.

AIM

This pilot study tests the hypothesis that ingestion of an amount of BJ sufficient to raise the blood NO level two-to three-fold, decreases Transcranial Doppler (TCD) measured CAIx.

MATERIALS AND METHODS

Ten healthy young-adult African-American women were studied at two levels of submaximal exercise, 40% and 80% of their predetermined peak oxygen consumptions. The subjects ingested nitrate-free orange juice (OJ, control) and an isocaloric BJ beverage (1.5 mg/mL nitrate, 220 Cal), on different days, 1-2 weeks apart.

RESULTS

The BJ treatment increased blood NO and decreased systolic BP at rest and at the two levels of exercise. The BJ treatment decreased CAIx only at the two levels of exercise (from 79 ± 2% to 62 ± 2% and from 80 ± 2% to 60 ± 3%, p<0.05). Exercise increased TCD-measured resistance and pulsatility indices (RIx, PIx) without changing AIx. The BJ treatment had no effect on RIx and PIx.

CONCLUSION

These findings suggest that decreased CAIx associated with aerobic exercise reflects the change in cerebral haemodynamics resulting from dietary nitrate supplementation. Future studies should determine whether the BJ-induced decrement in CAIx is correlated with an improvement in brain function.

Impact of interactions between risk alleles on clinical endpoints in hypertension

OBJECTIVE

Impairment of the renin-angiotensinogen-aldosterone system (RAAS), one of the characteristics of essential hypertension (EH), imbalances vascular homeostasis. Despite inconsistent reports on individual single nucleotide polymorphisms (SNPs) as a major predictor of EH, interactions among RAAS genetic variants are rarely investigated.

METHODS

Using SNP markers, we studied potential interactions between angiotensin 1 converting enzyme (ACE), angiotensinogen (AGT), angiotensin II-type 1 receptor (AGTR1), and α adducin (ADD1) variants and their correlation with clinical endpoints in 545 individuals with hypertension and 400 age- and ethnicity-matched unrelated controls. Generalised multifactor dimensionality reduction (GMDR) analysis identified the models for genotype interaction.

RESULTS

Although the results on single genes were significant, gene-gene interactions were more reliable and promising as markers in predisposing hypertension. The best models to represent association of multi-locus interactions with augmented hypertension susceptibility were: (a) within gene 4-locus model comprised of AGT SNPs -217G/A, -20A/C, -6G/A and 235M/T (p=0.022, OR 6.1); and (b) between genes 5-locus model comprised of AGT -217G/A, -20A/C, -6G/A, 235M/T and ACE I/D (p=0.05, OR 4.6). Stratification of 4- and 5-locus GMDR models on the basis of risk alleles from ≤1 to ≥7 increased the ORs from 2.8 to 36.1 and from 0.9 to 16.1, respectively. Moreover, compared to ≤1 risk alleles the ≥7 interacting risk alleles in both 4- and 5-locus models showed an increment of 14.2% and 11.1% in systolic blood pressure, 7.7% and 1.1% in diastolic blood pressure, and 10.5% and 5.1% in mean arterial pressure, respectively, in patients.

CONCLUSIONS

Interactions among the genetic loci of RAAS components may be used as a predictor for susceptibility to hypertension.

CYBA (p22phox) variants associate with blood pressure and oxidative stress markers in hypertension: a replication study in populations of diverse altitudes

CYBA (p22(phox)) is an integral constituent of the NADPH oxidases and is consequently a main component of oxidative stress, which is strongly associated with hypertension. This study investigates the contribution of CYBA polymorphisms toward the complex etiology of hypertension in two ethnically different populations, one located at a high altitude and the other at a low altitude. The significance of CYBA single nucleotide polymorphisms and their correlation with clinical and biochemical phenotypes were investigated in age- and ethnicity-matched unrelated permanent high-altitude residents (>3500 m) comprising 245 controls and 241 patients. The results were replicated in a second population comprising 935 controls and 545 patients who lived at a low altitude (<200 m). The analysis of covariance revealed that CYBA risk alleles and their haplotypes, rs8854A/rs9932581G/rs4873C and rs8854G/rs9932581G/rs4873C, were positively correlated with clinical parameters, for example, systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP), and biochemical parameters, for example, 8-isoPGF2α level, and inversely correlated with catalase activity in patients compared with controls (P⩽0.01, each). Conversely, the protective alleles and their haplotype, rs8854G/rs9932581A/rs4873T, were inversely correlated with SBP, DBP, MAP and 8-isoPGF2α level, and positively correlated with catalase activity (P⩽0.001, each). Furthermore, correlation analysis between the clinical and biochemical parameters revealed a positive correlation of SBP, DBP and MAP with 8-isoPGF2α levels and a negative correlation with catalase activity in both populations (P<0.0001, each). CYBA (p22(phox)) variants influence the markers of oxidative stress and are associated with hypertension.