Genetic influences of beta-adrenoceptor polymorphisms on arterial functional changes and cardiac remodeling in hypertensive patients

Are you as old as your arteries? Comparing arterial aging in Japanese and European patient groups using cardio-ankle vascular index

BACKGROUND

Most comparisons of arterial stiffness between ethnic groups focus on pulse wave velocity. This study used the cardio-ankle vascular index (CAVI) in European compared to Japanese individuals to investigate how cardiovascular risk factors affect arterial aging across geographic regions.

METHODS

Four hundred and ninety-four European and 1044 Japanese individuals underwent measurements of CAVI, blood pressure and information on cardiovascular risk factors. Both datasets included individuals with 0-5 cardiovascular risk factors.

RESULTS

Average CAVI was higher in the Japanese than the European group in every age category, with significant differences up to 75 years for males and 85 for females. The correlation of CAVI with age, controlled for cardiovascular risk factors, was slightly higher in Japanese females (r = 0.594 vs. Europeans r = 0.542) but much higher in European males (r = 0.710 vs. Japanese r = 0.511). There was a significant correlation between CAVI and total cardiovascular risk factors in the Japanese (r = 0.141, P < 0.001) but not the European group. On linear regression, average CAVI was significantly dependent on age, sex, diabetes, BMI, SBP and geographic region. When divided into 'healthy' vs. 'high risk', the healthy group had a steeper correlation with age for Europeans (r = 0.644 vs. Japanese r = 0.472, Fisher's Z P < 0.001), whereas in the high-risk group, both geographic regions had similar correlations.

CONCLUSION

Japanese patient groups had higher arterial stiffness than Europeans, as measured by CAVI, controlling for cardiovascular risk factors. Europeans had greater increases in arterial stiffness with age in healthy individuals, particularly for males. However, cardiovascular risk factors had a greater impact on the Japanese group.

The mutation of Trp64Arg in β3-adrenoreceptor-encoding gene is significantly associated with increased hypertension risk and elevated blood pressure: a meta-analysis

This meta-analysis was implemented to test the association of a missense mutation, Trp64Arg, in β3-adrenoreceptor-encoding gene (ADRB3) with both hypertension risk and blood pressure (BP) changes. A systematic search of three publicly-available databases was launched to look for articles published as of December 2016. Qualification appraisal and data extraction were independently done by two researchers. Pooled estimates were expressed as odds ratio (OR) or weighted mean difference (WMD), and their 95% confidence intervals (95% CIs). There were separately 21 (3750/4225 patients/controls) and 17 (6100 subjects) individual studies for hypertension risk and BP changes. Integral analyses revealed that Trp64Arg mutation was associated with the significantly increased risk of hypertension, and particularly, the 64Trp/64Arg heterozygote carriers were 1.23-times more likely to develop hypertension compared with the 64Trp/64Trp homozygote carriers (OR = 1.23, 95% CI: 1.02∼1.46, P = 0.021). Publication bias was extremely low for all integral comparisons. In stratified analyses, significance was spotted in populations of Chinese descent, in retrospective studies, in hospital-based studies, in age-matched case-control studies, in studies enrolling patients with mean body mass index < 25 kg/m² and in studies with total sample size ≥ 240. Heterogeneity was improved for most stratified comparisons. Further in hypertensive patients, the 64Trp/64Arg heterozygote carriers had significantly higher systolic (WMD = 0.87 mmHg, 95% CI: 0.39∼1.35, P < 0.001) and diastolic (WMD = 0.88 mmHg, 95% CI: 0.59∼1.17, P < 0.001) BP than 64Trp/64Trp homozygote carriers. Altogether, ADRB3 gene Trp64Arg mutation was significantly associated with an increased predisposition toward hypertension and elevated systolic/diastolic BP in hypertensive patients, suggesting that Trp64Arg is an important hypertension-susceptibility marker.

Roles of catecholamine related polymorphisms in hypertension

The objective of this review is to summarize current data obtained so far in catecholamine-essential hypertension (EH) relationships on a genetic basis. As the major elements driving the sympathetic system’s actions, catecholamines modulate a variety of physiological processes and mutations related to the system. This could generate serious disorders, such as severe mental illnesses, stress-induced disorders, or impaired control of blood pressure or motor pathways. EH is idiopathic, and the genetic basis of its causes and substantial interindividual discrepancies in response to different types of treatments are the focus of interest. Susceptibility to disease or efficacy of treatments are thought to reflect genomic variabilities among individuals. Therefore, outlining the available knowledge in functional genetic polymorphisms linked to EH will make the picture clearer and will help to establish future prospects in the field.

Genetic determinants of arterial stiffness

Stiffness of large arteries (called arteriosclerosis) is an independent predictor of cardiovascular morbidity and mortality. Although previous studies have shown that arterial stiffness is moderately heritable, genetic factors contributing to arterial stiffness are largely unknown. In this paper, we reviewed the available literature on genetic variants that are potentially related to arterial stiffness. Most variants have shown mixed depictions of their association with arterial stiffness across multiple studies. Various methods to measure arterial stiffness at different arterial sites can contribute to these inconsistent results. In addition, studies in patient populations with hypertension or atherosclerosis may overestimate the impact of genetic variants on arterial stiffness. Future studies are recommended to standardize current measures of arterial stiffness in different age groups. Studies conducted in normal healthy subjects may also provide better opportunities to find novel genetic variants of arterial stiffness.

Assessment of arterial stiffness using applanation tonometry

Augmentation index (AIx) and pulse wave velocity (PWV) assess functional and structural aspects of the vascular wall and are independent markers of cardiovascular morbidity and mortality. Like blood pressure, many factors, genetic, structural, and physiological, affect AIx and PWV. AIx and PWV can be assessed noninvasively using applanation tonometry. The technique is simple, but comes with a number of practical and technical limitations that have not been well documented and (or) explored. This review considers pulse wave analysis in the context of cardiovascular disease, and considers its limitations. Data are presented indicating that the placement of the probe is critical, and that the amplitude of the obtained signal is related to the variability in measurements. On a more theoretical note, issues are discussed regarding the applied transfer functions that are built in the devices to assess central AIx from peripheral waveforms. Altogether, PWV and its analysis are useful additions to the arsenal of parameters that can be used to assess vascular health and to estimate vascular risk. Yet, our analysis underscores the necessity for precise operating procedures, and calls for transparency regarding the applied transfer functions of commercial devices.

-374 T/A polymorphism in RAGE gene is associated with onset of diabetes mellitus, atherosclerosis, and renal dysfunction in patients with hypertension

Receptor of advanced glycation end products (RAGE) is reportedly linked with chronic inflammatory diseases due to aging or diabetes. The aim of this study was to show how -374 T/A RAGE has an impact on systemic vascular damage and renal function. The study subjects were a total of 468 essential hypertension patients from the Non-Invasive Atherosclerotic Evaluation in Hypertension (NOAH) study cohort. We prospectively examined the association of -374 T/A RAGE with their prognoses and investigated the correlation between -374 T/A RAGE and multiple clinical parameters. Kaplan-Meier analysis did not show a significant association of -374 T/A RAGE with total mortality or the prevalence of cardiovascular events. Carriers of the A allele showed a significantly higher prevalence of diabetes mellitus (DM) and lower estimated glomerular filtration rate (eGFR) than subjects without this allele. In subjects with DM, carriers of the A allele showed a significantly lower eGFR. These significant correlations were only seen in male subjects. Carriers of the A allele of -374 T/A RAGE show an independent risk of atherosclerosis and reduced renal function in male hypertensive patients with DM.

A review of genetics, arterial stiffness, and blood pressure in African Americans

The prevalence of hypertension in African Americans in the USA is among the highest in the world and increasing. The identification of genes and pathways regulating blood pressure in African Americans has been challenging. An early predictor of hypertension is arterial stiffness. The prevalence of arterial stiffness is significantly higher in African Americans compared to Caucasians. Approximately 20 % of the variance in arterial stiffness is estimated to be heritable. Identifying genes and biological pathways regulating arterial stiffness may provide insight into the genetics underlying the increased risk of hypertension in African Americans. This paper reviews the genetic findings to date in the area of arterial stiffness and blood pressure in African Americans with an emphasis on the current limitations and new efforts to move the field forward.

Genetic determinants of blood pressure responses to caffeine drinking

BACKGROUND

The widely observed between-subject variability in cardiovascular responses to coffee may have a genetic basis.

OBJECTIVE

We evaluated acute blood pressure (BP) responses to caffeine and explored whether they are influenced by candidate gene variants affecting caffeine metabolism (for cytochrome P450 1A2), adenosine metabolism (for adenosine receptor and AMP deaminase), or catecholamine receptors.

METHODS

We recruited 110 healthy male habitual moderate coffee drinkers who refrained from drinking coffee on the day preceding the study. Each subject underwent ambulatory BP monitoring at 6-min intervals for 2 h. Each participant was administered, in a double-blind design, 40 mL of either a decaffeinated coffee preparation plus 3 mg caffeine/kg (caf) or the corresponding vehicle (decaf). The protocol was repeated 24 h later with the alternative preparation. Blood samples were collected for genetic and plasma caffeine and catecholamine evaluations.

RESULTS

Compared with decaf, caf was associated with a mean (± SD) significant increase in systolic BP of 4 ± 12 mm Hg and in diastolic BP of 3 ± 10 mm Hg (P < 0.001 for both). Plasma caffeine and adrenaline increased after caf, but not after decaf. Of 11 gene polymorphisms analyzed, a relation was observed between the ADORA2A TT variant and the change in SBP peak and between the ADRA2B I variant and the changes in both SBP mean and peak; mean peak change in SBP; these variants were associated with increased SBP responses to caf.

CONCLUSIONS

Variability in the acute BP response to coffee may be partly explained by genetic polymorphisms of the adenosine A2A receptors and α(2)-adrenergic receptors. This trial is registered at clinicaltrials.gov as NCT01330680.

Genetics and pathophysiology of arterial stiffness

Arterial stiffness is a cardiovascular risk factor that is independent of arterial pressure. Clinically, carotid-femoral pulse wave velocity (PWV) is the gold-standard parameter of arterial stiffness. Recent genetic studies have revealed specific genes that contribute to arterial stiffening. Here we review the recent findings on genome-wide linkage analyses and candidate gene polymorphism association studies. We also focus on the latest advances in the identification of gene variants affecting PWV using high density array single nucleotide polymorphism technology in a recent genome-wide association (GWA) study. Linkage and polymorphism studies revealed a first group of genes affecting the renin-angiotensin-aldosterone system, elastic fibre structural components, metalloproteinases, and the NO pathway. A second group of genes, identified by polymorphism association studies and possibly involved in the pathophysiology of arterial stiffness, includes beta-adrenergic receptors, endothelin receptors, and inflammatory molecules. The last group of genes, identified by GWA studies and unrelated to currently suspected mechanisms of arterial stiffness, may target transcriptional pathways controlling gene expression, differentiation of vascular smooth muscle cells, apoptosis of endothelial cells, or the immune response within the vascular wall.

New bearings in pharmacotherapeutic strategies: Pharmacogenetics and gene therapy

<zakljucak> Slicno drugim, novim terapijskim konceptima i genska terapija je puno obecavala, ali za sada je jos u razvoju. Glavni izazov ostaje unosenje pravog gena na pravo mesto, u pravu celiju i obezbedjenje adekvatne ekspresije, uz minimalna nezeljena dejstva. Iako se najvise radi na virusnim vektorima, smatra se da buducnost genske terapije cine znatno bezbedniji nevirusni sistemi. Bilo je izvesnih promasaja u genskoj terapiji, sto je dovelo do sumnje i zabrinutosti u siroj populaciji. Medjutim, razvoj genske terapije je realnost, kao i cinjenica da ona ima svoje mesto u medicini. Vazno je istaci da genskoj terapiji treba pristupati sa izuzetno visokim stepenom naucne, strucne i eticke odgovornosti, jer se ne moze iskljuciti mogucnost genetskih manipulacija opasnih za ljudsko zdravlje.