Contribution of Four Polymorphisms in Renin-Angiotensin-Aldosterone-Related Genes to Hypertension in a Thai Population

The frequency of the ACE I/D polymorphism in South America: a systematic review and meta-analysis

Angiotensin-converting enzyme (ACE) is a key component of the renin-angiotensin system and plays an important role in homeostasis and maintenance of blood pressure. However, little is known about allele and genotypic frequencies, as well as phenotypic characteristics associated with ACE polymorphism genotypes in South American populations. This study aimed to verify the allelic predominance and genotype frequency of ACE I/D polymorphism in South America and its association with the main diseases and related conditions. We conducted a systematic review considering studies published in the last 25 years available in PubMed, Scielo, LILACS, LIPECS, Coleciona SUS, CUMED, BINACIS, IBECS, and MEDLINE databases, resulting in the inclusion of 121 studies. Quality of the studies was assessed according to the Strengthening the Reporting of Genetic Association (STREGA) guidelines. We mapped the frequency of the ACE I/D polymorphism in South American populations. 8,856 (32.1%) subjects were DD, 13,050 were ID (47.4%), and 5,644 were II (20.5%) carriers. The main associated conditions included systemic arterial hypertension and other cardiovascular conditions, cardiorespiratory or respiratory characteristics, physical activity level, kidney conditions, aging-related diseases, as well as different types of cancers and metabolic conditions. 61.1% of the studies found no significant association between the respective conditions investigated and the ACE I/D polymorphism. Considering DD genotype or D allele, 21.5% of the studies observed negative and 4.9% positive outcomes. Regarding ID genotype, 4.1% of the studies identified negative and 0.8% positive outcomes, and for II genotype or I allele, 4.1% of the results had negative and 10.7% positive associations.

Analysis of the combined effect of rs699 and rs5051 on angiotensinogen expression and hypertension

Background

Hypertension (HTN) involves genetic variability in the renin-angiotensin system and influences antihypertensive response. We previously reported that angiotensinogen (AGT) messenger RNA (mRNA) is endogenously bound by miR-122-5p and rs699 A > G decreases reporter mRNA in the microRNA functional-assay PASSPORT-seq. The AGT promoter variant rs5051 C > T is in linkage disequilibrium (LD) with rs699 A > G and increases AGT transcription. The independent effect of these variants is understudied due to their LD therefore we aimed to test the hypothesis that increased AGT by rs5051 C > T counterbalances AGT decreased by rs699 A > G, and when these variants occur independently, it translates to HTN-related phenotypes.

Methods

We used in silico, in vitro, in vivo, and retrospective models to test this hypothesis.

Results

In silico, rs699 A > G is predicted to increase miR-122-5p binding affinity by 3%. Mir-eCLIP results show rs699 is 40-45 nucleotides from the strongest microRNA-binding site in the AGT mRNA. Unexpectedly, rs699 A > G increases AGT mRNA in an AGT-plasmid-cDNA HepG2 expression model. Genotype-Tissue Expression (GTEx) and UK Biobank analyses demonstrate liver AGT expression and HTN phenotypes are not different when rs699 A > G occurs independently from rs5051 C > T. However, GTEx and the in vitro experiments suggest rs699 A > G confers cell-type-specific effects on AGT mRNA abundance, and suggest paracrine renal renin-angiotensin-system perturbations could mediate the rs699 A > G associations with HTN.

Conclusions

We found that rs5051 C > T and rs699 A > G significantly associate with systolic blood pressure in Black participants in the UK Biobank, demonstrating a fourfold larger effect than in White participants. Further studies are warranted to determine if altered antihypertensive response in Black individuals might be due to rs5051 C > T or rs699 A > G. Studies like this will help clinicians move beyond the use of race as a surrogate for genotype.

AGT, CYP11B2 & ADRB2 gene polymorphism & essential hypertension (HT): A meta-analysis

Background & objectives The results of the genetic association studies between the selected candidate genes and hypertension (HT) contradicted across different populations. Majority of the meta-analyses carried out did not consider population genetic ancestry as a confounding factor. Therefore, this meta-analysis attempted to consolidate and re-evaluate the findings of the association between the selected candidate variants (AGT-rs699, CYP11B2-rs1799998, ADRB2-rs1042713 and rs1042714) and HT, by categorizing the genotyping data based on known genetic ancestry, and/or major geographical populations. Methods Publications were retrieved from PubMed, Cochrane and World of Science. The included articles were further divided into different populations based on their known genetic and/or geographical ancestry. Results AGTrs699-G was significantly associated with HT among Indians for (i) allele [P=0.03, Odds ratio (OR): 1.37, 95% Confidence Interval (CI): 1.03-1.82], and (ii) dominant mode of inheritance (P=0.009, OR:1.45, 95% CI: 1.09-1.91). CYP11B2rs1799998-G was significantly associated with HT in Europeans for (i) allele (P=6.9 × 10-5, OR: 0.82, 95% CI: 0.74-0.9), (ii) recessive (P=6.38 × 10-5, OR: 0.7, 95% CI: 0.59-0.83) and (iii) dominant mode of inheritance (P=0.008, OR: 0.81, 95% CI: 0.7-0.94). ADRB2-rs1042713-G was significantly associated with HT in east Asians for (i) allele (P=0.01, OR: 1.26, 95% CI: 1.05-1.51), and (ii) recessive mode of inheritance (P=0.04, OR: 1.36, 95% CI: 1.01-1.83). Interpretation & conclusions Different genotype and allele frequencies in diverse populations result in different genetic associations with HT across populations. This meta-analysis finding provides an update and summary of the genetic association between the selected simple nucleotide polymorphism (SNPs) and HT across different populations and essential insights into selecting appropriate pharmacogenetic marker(s) for effective HT management in populations of different ancestries.

Mathematical modelling of the influence of ACE I/D polymorphism on blood pressure and antihypertensive therapy

The angiotensin-converting enzyme (ACE) gene (ACE) insertion/deletion (I/D) polymorphism raises the possibility of personalising ACE inhibitor therapy to optimise its efficiency and reduce side effects in genetically distinct subgroups. However, the extent of its influence among these subgroups is unknown. Therefore, we extended our computational model of blood pressure regulation to investigate the effect of the ACE I/D polymorphism on haemodynamic parameters in humans undergoing antihypertensive therapy. The model showed that the dependence of blood pressure on serum ACE activity is a function of saturation and therefore, the lack of association between ACE I/D and blood pressure levels may be due to high ACE activity in specific populations. Additionally, in an extended model simulating the effects of different classes of antihypertensive drugs, we explored the relationship between ACE I/D and the efficacy of inhibitors of the renin-angiotensin-aldosterone system. The model predicted that the response of cardiovascular and renal parameters to treatment directly depends on ACE activity. However, significant differences in parameter changes were observed only between groups with high and low ACE levels, while different ACE I/D genotypes within the same group had similar changes in absolute values. We conclude that a single genetic variant is responsible for only a small fraction of heredity in treatment success and its predictive value is limited.

Genetic Factors Contributing to the Pathogenesis of Essential Hypertension in Two African Populations

The African continent has the highest prevalence of hypertension globally, with South Africa reporting the highest prevalence in Southern Africa. While the influence of genetic variability in the pathogenesis of hypertension is well described internationally, limited reports are available for African populations. This study aimed to assess the association of genetic variants and essential hypertension in a cohort of two ethnic South African population groups. Two hundred and seventy-seven hypertensive and one hundred and seventy-six normotensive individuals were genotyped for 78 variants. Genotyping was performed using the Illumina GoldenGate Assay and allele-specific polymerase chain reaction. The association of variants was assessed using the Fisher Exact test under the additive and allelic genetic models, while multivariate logistic regression was used to predict the development of hypertension. Five variants (CYP11B2 rs179998, AGT rs5051 and rs699, AGTR1 rs5186, and ACE rs4646994) were significantly associated with essential hypertension in the cohort under study. Furthermore, AGTR1 rs5186 and AGT rs699 were identified as risk factors for the development of hypertension in both ethnic groups. In two ethnic South African populations, an association was observed between renin-angiotensin-aldosterone system (RAAS)-related genes and the development of hypertension.

Effects of AGT and AGTR1 Genetic Polymorphisms and Changes in Blood Pressure Over a Five-Year Follow-Up

Purpose

The renin-angiotensin system plays an important role in the central regulation of blood pressure (BP). Genetic variations of angiotensinogen (AGT) and angiotensin II type 1 receptor (AGTR1) may increase susceptibility to elevated BP and hypertension. This study investigated the effects of AGT rs699 and AGTR1 rs5186 single nucleotide polymorphisms (SNPs) on BP at baseline and at a 5-year follow-up.

Paticipants and Methods

The study population consisted of participants from the Electricity Generating Authority of Thailand cohort study (n=354); data were collected at baseline (2013) and 5 years later (2018). Genotyping of the two SNPs was performed using TaqMan® assay and statistical analyses were performed with SNPStats software.

Results

The frequencies of the two SNPs were within the Hardy-Weinberg equilibrium (p=0.22 for AGT rs699 and p=0.06 for AGTR1 rs5186). For each SNP, mutant genotypes were significantly associated with increased systolic BP and/or diastolic BP in the codominant and recessive models. Risk alleles of AGT rs699 and AGTR1 rs5186 were associated with increased odds of hypertension and hypertension with metabolic syndrome at follow-up.

Conclusion

Overall, our results suggest that polymorphisms of genes in the renin-angiotensin system increase susceptibility to the development and progression of hypertension and the development of the metabolic syndrome.

Advances in pathogenesis and treatment of essential hypertension

Hypertension is a significant risk factor for cardiovascular and cerebrovascular diseases and the leading cause of premature death worldwide. However, the pathogenesis of the hypertension, especially essential hypertension, is complex and requires in-depth studies. Recently, new findings about essential hypertension have emerged, and these may provide important theoretical bases and therapeutic tools to break through the existing bottleneck of essential hypertension. In this review, we demonstrated important advances in the different pathogenesis areas of essential hypertension, and highlighted new treatments proposed in these areas, hoping to provide insight for the prevention and treatment of the essential hypertension.

Endothelium function biomarkers and carotid intima-media thickness changes in relation to NOS3 (rs2070744) and GNB3 (rs5443) genes polymorphism in the essential arterial hypertension

Objective. The aim of the present study was to clarify the endothelial function biomarkers and carotid "intima media" thickness (IMT) changes in relation to GNB3 (rs5443) and NOS3 (rs2070744) genes polymorphism in the essential arterial hypertension (EAH). Methods. One-hundred EAH patients (48 - control) participated in the case-control study. Soluble vascular cell adhesion molecule (sVCAM-1), total NO metabolites (NO₂ ^-+NO₃ ^-), transcriptional activity of NOS3 gene, endothelium-dependent flow-mediated dilation of the brachial artery (FMD BA), and carotid IMT were studied. GNB3 (rs5443) and NOS3 (rs2070744) genotyping was performed by TaqMan probes (CFX96™Real-Time PCR). Results. The connection of NOS3 (rs2070744) with decreased total NO metabolites (F=71.11; p<0.001), reduced NOS3 genes transcription activity (F=8.71; p<0.001) and increased sVCAM-1 (F=6.96; p=0.002), especially in the C-allele carriers (particularly in CC-genotype patients with lower NO - 16.46% and 40.88%; p<0.001), lowered the transcription activity of NOS3 gene - 46.03% 7 times (p<0.001), and become higher sVCAM-1 - 35.48% and 89.48% (p<0.001), respectively. ANOVA did not confirm the association of GNB3 (rs5443) gene with endothelial function and carotid IMT. Severe EAH was associated with increased carotid IMT - 50.0% (p<0.001) and 57.14% (p=0.007), wider carotid arteries - 17.36% (p=0.012) and 21.79% (p=0.004), and decreased NOS3 genes transcription activity - 34.54% (p=0.003). Atherosclerotic plaques were unilateral - 24.77% (χ²=5.35; p=0.021) or bilateral - 27.62% (χ²=5.79; p=0.016). IMT---gt---0.9 mm was followed by a higher BP (p<0.001), FMD BA 11.80% decrease with compensatory increase in carotid arteries diameters - 17.38% and 21.99% (p<0.001) and sVCAM-1 by 20.49% (p=0.005). Conclusion. NOS3 (rs2070744), but not GNB3 (rs5443), gene associated with the essential arterial hypertension severity relying upon the endothelial function impairment and NOS3 genes reduced transcription activity.

Quantitative Real-Time Analysis of Differentially Expressed Genes in Peripheral Blood Samples of Hypertension Patients

Hypertension (HTN) is considered one of the most important and well-established reasons for cardiovascular abnormalities, strokes, and premature mortality globally. This study was designed to explore possible differentially expressed genes (DEGs) that contribute to the pathophysiology of hypertension. To identify the DEGs of HTN, we investigated 22 publicly available cDNA Affymetrix datasets using an integrated system-level framework. Gene Ontology (GO), pathway enrichment, and transcriptional factors were analyzed to reveal biological information. From 50 DEGs, we ranked 7 hypertension-related genes (p-value < 0.05): ADM, ANGPTL4, USP8, EDN, NFIL3, MSR1, and CEBPD. The enriched terms revealed significant functional roles of HIF-1-α transcription; endothelin; GPCR-binding ligand; and signaling pathways of EGF, PIk3, and ARF6. SP1 (66.7%), KLF7 (33.3%), and STAT1 (16.7%) are transcriptional factors associated with the regulatory mechanism. The expression profiles of these DEGs as verified by qPCR showed 3-times higher fold changes (2−ΔΔCt) in ADM, ANGPTL4, USP8, and EDN1 genes compared to control, while CEBPD, MSR1 and NFIL3 were downregulated. The aberrant expression of these genes is associated with the pathophysiological development and cardiovascular abnormalities. This study will help to modulate the therapeutic strategies of hypertension.

Association of AGTR1 (rs5186), VDR (rs2228570) genes polymorphism with blood pressure elevation in patients with essential arterial hypertension

Essential arterial hypertension (EAH) is a polygenic disease due to environmental, genetic, and epigenomic factors. The study aimed to establish the association of single nucleotide polymorphism (SNP) of AGTR1 (rs5186) and VDR (rs2228570) genes with the blood pressure (BP) elevation in EAH patients. 100 EAH subjects with hypertensive-mediated organ damaging (2^nd stage), moderate, high, or very high cardiovascular risk were recruited into the case-control study. There were 70.83% females and 29.17% males, mean age 57.86±7.81 y.o. The control group included 60 healthy individuals of relevant age and gender distribution. Estimation of AGTR1 (rs5186) and VDR (rs2228570) gene polymorphism was performed by Real-Time Polymerase Chain Reaction. In EAH patients, the AGTR1 gene (rs5186) mutation occurs with a frequency of 2.78% in the absence of such among healthy individuals. The VDR (rs2228570) gene mutation occurs with a frequency of 23% cases. The C-allele carriers’ (AGTR1 gene) numbers with 2^nd and 3^rd BP values degree dominate over AA-genotype patients by 25.32% (_χ2=4.52; p=0.033). VDR gene (rs2228570) polymorphic variants do not link to BP elevation values. Thus, the C-allele of the AGTR1 gene (rs5186) is associated with BP elevation in hypertensive patients. BP values do not depend on VDR gene (rs2228570) polymorphic variants.

Association of -344C/T polymorphism in the aldosterone synthase (CYP11B2) gene with cardiac and cerebrovascular events in Chinese patients with hypertension

Objective

Several recent studies have shown that the aldosterone synthase gene (CYP11B2) −344C/T polymorphism is related to cardiovascular diseases. However, whether the −344C allele influences the incidence of cardiovascular diseases in Chinese patients with hypertension is unclear.

Methods

Chinese patients with essential hypertension were genotyped for the −344C/T polymorphism in CYP11B2 (n = 755; CC, n = 112; CT, n = 361; TT, n = 282) and followed for 11 years for major adverse cardiovascular events (MACEs), including stroke, onset of coronary artery disease (CAD), and CAD-related death. Established cardiovascular risk factors were used to adjust the multivariate Cox analysis.

Results

After a mean follow-up period of 7.60 ± 1.12 years, a significantly higher incidence of MACEs was seen in patients with the CC genotype than in those with the CT and TT genotypes. The CC variant was significantly and independently predictive of MACEs (hazard ratio = 2.049), CAD (hazard ratio = 1.754), and stroke (hazard ratio = 2.588), but not CAD-related stroke or death.

Conclusion

The CYP11B2 −344 CC genotype is a risk factor for CAD and stroke, independent of other established cardiovascular risk factors in Chinese patients with hypertension.