Association between angiotensin II Type 2 receptor gene A/C3123 polymorphism and high-density lipoprotein cholesterol with hypertension in asymptomatic women

OBJECTIVE

The present study investigated the association between the angiotensin II type 2 receptor (AT2R) gene adenine/cytosine (A/C)-3123 polymorphism and cardiometabolic variables in subjects with and without hypertension.

METHODS

Cardiometabolic variables, in addition to genotyping by an allele-specific DNA assay, were measured in 161 asymptomatic community-dwelling Japanese women (age range 30-83 years). They were divided into hypertensive (n = 82, age 50-81 years) and nonhypertensive (n = 79, age 30-83 years) subjects.

RESULTS

The A-allele carriers (n = 53) showed significantly lower high-density lipoprotein cholesterol (HDL-C) levels than the non-A-allele carriers (n = 26) among nonhypertensive subjects (1.45 ± 0.38 vs. 1.66 ± 0.33 mmol/l, p = 0.02). Even when multiple-adjusted analyses were performed, the HDL-C levels continued to differ significantly and independently of other variables, including the body mass index and insulin resistance index, between A-allele and non-A-allele carriers. However, this association was not observed among hypertensive subjects.

CONCLUSION

The present study demonstrated that A-allele carriers had significantly lower HDL-C levels than did non-A-allele carries among nonhypertensive women, while this association was not observed among hypertensive women. This indicates that the A/C3124 polymorphism may be a marker associated with HDL metabolism by hypertension. This was a small study, so further research is warranted to confirm the observed association.

Angiogenic factors and their soluble receptors predict organ dysfunction and mortality in post-cardiac arrest syndrome

INTRODUCTION

Post-cardiac arrest syndrome (PCAS) often leads to multiple organ dysfunction syndrome (MODS) with a poor prognosis. Endothelial and leukocyte activation after whole-body ischemia/reperfusion following resuscitation from cardiac arrest is a critical step in endothelial injury and related organ damage. Angiogenic factors, including vascular endothelial growth factor (VEGF) and angiopoietin (Ang), and their receptors play crucial roles in endothelial growth, survival signals, pathological angiogenesis and microvascular permeability. The aim of this study was to confirm the efficacy of angiogenic factors and their soluble receptors in predicting organ dysfunction and mortality in patients with PCAS.

METHODS

A total of 52 resuscitated patients were divided into two subgroups: 23 survivors and 29 non-survivors. The serum levels of VEGF, soluble VEGF receptor (sVEGFR)1, sVEGFR2, Ang1, Ang2 and soluble Tie2 (sTie2) were measured at the time of admission (Day 1) and on Day 3 and Day 5. The ratio of Ang2 to Ang1 (Ang2/Ang1) was also calculated. This study compared the levels of angiogenic factors and their soluble receptors between survivors and non-survivors, and evaluated the predictive value of these factors for organ dysfunction and 28-day mortality.

RESULTS

The non-survivors demonstrated more severe degrees of organ dysfunction and a higher prevalence of MODS. Non-survivors showed significant increases in the Ang2 levels and the Ang2/Ang1 ratios compared to survivors. A stepwise logistic regression analysis demonstrated that the Ang2 levels or the Ang2/Ang1 ratios on Day 1 independently predicted the 28-day mortality. The receiver operating characteristic curves of the Ang2 levels, and the Ang2/Ang1 ratios on Day 1 were good predictors of 28-day mortality. The Ang2 levels also independently predicted increases in the Sequential Organ Failure Assessment (SOFA) scores.

CONCLUSIONS

We observed a marked imbalance between Ang1 and Ang2 in favor of Ang2 in PCAS patients, and the effect was more prominent in non-survivors. Angiogenic factors and their soluble receptors, particularly Ang2 and Ang2/Ang1, are considered to be valuable predictive biomarkers in the development of organ dysfunction and poor outcomes in PCAS patients.

Gene polymorphisms of ACE and the angiotensin receptor AT2R1 influence serum ACE levels in sarcoidosis

Angiotensin converting enzyme (ACE) is thought to influence susceptibility, disease progression, and/or outcome of sarcoidosis by functional mutations/polymorphisms of the ACE gene, such as the ACE gene deletion/insertion (D/I) polymorphism or the angiotensin receptors like the angiotensin II receptor type 1 (AT2R1) A1166 --> C polymorphism. The aim of our study was to examine the distribution of the ACE D/I genotypes and the AT2R1 A1166 --> C genotypes in sarcoidosis and healthy controls, and to test their influence on disease progression. In this study, we assessed ACE and AT2R1 genotypes by PCR in 264 healthy Caucasians and 95 sarcoidosis patients. Serum ACE levels were determined using a kinetic test. Genotyping sarcoidosis patients for the AT2R1 A166 --> C polymorphism revealed an increase in homozygous genotypes CC (sarcoidosis: 11.6%, controls: 9.2%) and AA (sarcoidosis: 61.1%, controls: 47.3%) but a lower frequency in heterozygous genotypes (sarcoidosis: 27,4%, controls: 43,5%; p = 0.024) which was more pronounced in male patients. The co-incidence of DI and AC was less frequent in patients with sarcoidosis, suggesting protection by the combination of DI and AC. The AT2R1 A1166 --> C gene polymorphism modulated the effect of the ACE D/I polymorphism on serum ACE levels with the A allele promoting its influence and the C allele reducing it. We conclude that neither the ACE D/I nor the AT2R1 A1166 --> C polymorphism has a role in sarcoidosis disease progression. In males, the homozygous AT2R1 genotypes CC and AA possibly increase the risk for sarcoidosis. Co-incidence of the heterozygous genotypes DI and AC might be protective against sarcoidosis.

C-reactive protein causes downregulation of vascular angiotensin subtype 2 receptors and systolic hypertension in mice

BACKGROUND

Chronic elevations in circulating C-reactive protein (CRP) are associated with a greater risk of hypertension. Whether elevations in CRP cause hypertension is unknown.

METHODS AND RESULTS

Chronic, conscious blood pressure (BP) measurements were performed by radiotelemetry in wild-type CF1 control and CF1 transgenic mice expressing rabbit CRP (CF1-CRP) under the regulation of the phosphoenolpyruvate carboxykinase promoter. Compared with controls, CF1-CRP mice had hypertension that was predominantly systolic, and the severity of hypertension varied in parallel with changes in CRP levels modulated by dietary manipulation. Mice that were hemizygous for the transgene with CRP levels of 9 microg/mL were also hypertensive, indicating that modest elevations in CRP are sufficient to alter BP. CRP transgenic mice had exaggerated BP elevation in response to angiotensin II and a reduction in vascular angiotensin receptor subtype 2 (AT2) expression. In contrast, the decline in BP with angiotensin receptor subtype 1 (AT1) antagonism and vascular AT1 abundance were unaltered, which indicates a selective effect of CRP on AT2. Ex vivo experiments further showed that the CRP-induced decrease in AT2 is a direct effect on the vascular wall, not requiring systemic responses, and that it is reversed by an NO donor, which indicates a role for NO deficiency in the process. In parallel, the chronic inhibition of NO synthase in wild-type mice attenuated vascular AT2 expression without affecting AT1.

CONCLUSIONS

These findings provide direct evidence for CRP-induced hypertension, and they further identify a novel underlying mechanism involving downregulation of AT2 related to NO deficiency.

Long-Term Prevention of Hypertension and End-Organ Damage in Ren-2 Transgenic Rats Is Achieved Only with Persistent but Not Transient AT1 Receptor Blockade

The aim of this study was first to evaluate the effects of persistent or transient blockade of the angiotensin II (ANG II) receptor AT(1) on the development of hypertension and end-organ damage in hypertensive Ren-2 transgenic rats (TGR), and second to assess the potential role of AT(2) receptors in the control of blood pressure (BP) in this monogenetic model of hypertension. Male heterozygous TGR and Hannover Sprague-Dawley (HanSD) rats fed a normal salt diet were treated from day 32 of age either persistently until the end of the experiment (day 100 of age) or transiently until day 56 of age with the selective AT(1) receptor antagonist candesartan or with the combination of candesartan and the AT(2) receptor antagonist PD 123319. Persistent treatment with candesartan completely prevented the rise in BP, proteinuria and the increase in left ventricular weight/body weight ratio, whereas transient treatment with candesartan was effective only as long as the drug was administered. In the presence of candesartan, PD 123319 was without effect. Our results show that in male heterozygous TGR persistent candesartan treatment completely prevented hypertension and end-organ damage as long as the drug was administered, whereas transient AT(1 )receptor blockade had no long-term effects.

[Differences of Angiotensin II receptor expression between systemic and pulmonary circulation in children with left-to-right shunt congenital cardiac lesions]

OBJECTIVE

It has been shown that angiotensin converting enzyme inhibitors (ACEI) can reduce the ratio of pulmonary and systemic circulation blood flow (Qp/Qs) and thus decrease the blood flow of left-to-right shunt in children with left-to-right shunt congenital cardiac lesions. This suggests that there are differences in the expression of Angiotensin II receptors between systemic and pulmonary circulation. This study aimed to explore the differences of Angiotensin II receptors type 1 and type 2 (AT1 and AT2 receptors) expression between systemic and pulmonary circulation in children with left-to-right shunt congenital cardiac lesions.

METHODS

Lung and skeletal muscular tissues were obtained from 20 children with left-to-right shunt congenital cardiac lesions by biopsy during operation. The specimens were stained by immunohistochemistry techniques for AT1 and AT2 receptors. The technique of morphometric analysis was used to measure the immunoreactivity of AT1 and AT2 receptors (expressed by IOD values) of pulmonary, skeletal muscular and pleural small vascular wall the diameter of which was 15-100 microm.

RESULTS

The immunoreactivities of AT1 and AT2 receptors of pulmonary small vascular walls [(124 +/- 95)x10(3) and (85 +/- 62)x10(3) respectively] were significantly lower than those of skeletal muscular [(219 +/- 156)x10(3) and (155 +/- 139)x10(3) respectively] and those of pleural small vascular walls [(279 +/- 191)x10(3) and (175 +/- 128)x10(3) respectively] in children with left-to-right shunt congenital cardiac lesions (P < 0.05).

CONCLUSIONS

The expression of AT1 and AT2 receptors in small vascular walls of systemic circulation was higher than that of pulmonary circulation in children with left-to-right shunt congenital cardiac lesions.