Aldosterone in vascular and metabolic dysfunction

Eight weeks of treatment with mineralocorticoid receptor blockade does not alter vascular function in individuals with and without type 2 diabetes

Aldosterone has been suggested to be involved in the microvascular complications observed in type 2 diabetes. We aimed to investigate the effect of mineralocorticoid receptor (MR) blockade on endothelial function in individuals with type 2 diabetes compared to healthy controls. We included 12 participants with type 2 diabetes and 14 controls. We measured leg hemodynamics at baseline and during femoral arterial infusion of acetylcholine and sodium nitroprusside before and 8 weeks into treatment with MR blockade (eplerenone). Acetylcholine infusion was repeated with concomitant n-acetylcysteine (antioxidant) infusion. No difference in leg blood flow or vascular conductance was detected before or after the treatment with MR blockade in both groups and there was no difference between groups. Infusion of n-acetylcysteine increased baseline blood flow and vascular conductance, but did not change the vascular response to acetylcholine before or after treatment with MR blockade. Skeletal muscle eNOS content was unaltered by MR blockade and no difference between groups was detected. In conclusion, we found no effect of MR blockade endothelial function in individuals with and without type 2 diabetes. As the individuals with type 2 diabetes did not have vascular dysfunction, these results might not apply to individuals with vascular dysfunction.

Endothelial mineralocorticoid receptor ablation confers protection towards endothelial dysfunction in experimental diabetes in mice

AIM

With diabetes comes a significant risk of macrovascular and microvascular complications. Circulating aldosterone levels increase in patients with diabetes. Aldosterone can directly affect vascular function via activation of the mineralocorticoid receptor (MR). We hypothesized that aldosterone via endothelial MR impairs endothelial function in a murine model of experimental diabetes.

METHOD

Endothelial cell-specific mineralocorticoid receptor knockout MR^flox/flox ; Tie2-Cre mice (ECMR-KO) and wild-type FVB littermates were subjected to an experimental type-1 diabetic model by low dose streptozotocin injections (55mg/kg/day) for five consecutive days. After 10 weeks of diabetes, second-order mesenteric resistance arteries were perfused ex vivo to evaluate vessel contractility and endothelial function. The effect of ex vivo incubation with aldosterone with and without the antagonist, spironolactone was determined.

RESULTS

Diabetic ECMR-KO and wild-type mice had similar, elevated, plasma aldosterone concentration while only diabetic wild-type mice displayed elevated urine albumin excretion and cardiac and kidney hypertrophy at 10 weeks. There were no differences in contraction (Emax and EC₅₀ ) to thromboxane receptor agonist (U46619) and elevated K⁺ between groups. Wild-type diabetic mice showed impaired acetylcholine (ACh)-dependent relaxation, while diabetic ECMR-KO mice had intact ACh-mediated relaxation. Aldosterone incubation ex vivo impaired ACh mediated relaxation and rendered responses similar to diabetic WT arteries. Direct, ex vivo aldosterone effects were absent in ECMR-KO animals. Ex vivo inhibitory effects of aldosterone on endothelial relaxation in arteries from WT were abolished by spironolactone.

CONCLUSION

These findings show that endothelial cell mineralocorticoid receptor activation accounts for diabetes-induced systemic endothelial dysfunction in experimental diabetes and may explain the cardiovascular protection by MR antagonists in diabetes.

Renal denervation inhibits the renin-angiotensin-aldosterone system in spontaneously hypertensive rats

This study was conducted to explore the effect of renal denervation (RDN) on the renin-angiotensin-aldosterone system (RAAS) in spontaneously hypertensive rats (SHRs). Our experimental rats were randomly divided into the RDN group conducted by painting 10% phenol on the bilateral renal nerves (RDNX), the shamoperation group simply painting with saline (Sham), and the normotension control group (WKY) following all the animal blood and tissues of kidney, hypothalamus, and adrenal gland collected and examined 2 weeks after RDN operation. We found that the aldosterone (ALD) levels in serum and tissues all decreased in the RDNX group compared with the Sham group (p < .05). Meantime, the expression of angiotensin II type1 receptor (AT1R) mRNA also exhibited significantly reduced by 2.22-fold in the RDNX group compared to the Sham group identical to the expression of AT1R protein in the renal cortex and outer stripe of the outer medulla (OSOM) subjected to denervation surgery, which manifested the lower ATIR protein expression than the Sham group (p < .05). Besides, the expression of angiotensin II (Ang II) protein in the cortex , OSOM, and inner stripe of the outer medulla were all attenuated by RDN in comparison with the Sham group (p < .05). RDN reduced intrarenal RAAS and circulating RAAS to lower blood pressure and repair renal function.

Comparison of biomarkers of endothelial dysfunction and microvascular endothelial function in patients with primary aldosteronism and essential hypertension

Introduction:

Studies have shown that primary aldosteronism (PA) has a higher risk of cardiovascular events than essential hypertension (EH). Endothelial dysfunction is an independent predictor of cardiovascular events. Whether PA and EH differ in the endothelial dysfunction is uncertain. Our study was designed to investigate the levels of biomarkers of endothelial dysfunction (Asymmetric dimethylarginine, ADMA; E-selectin, and Plasminogen activator inhibitor-1, PAI-1) and assess the microvascular endothelial function in patients with PA and EH, respectively.

Methods:

The biomarkers of endothelial dysfunction were measured by enzyme-linked immunosorbent assay (ELISA). Microvascular endothelial function was evaluated by Pulse amplitude tonometry (PAT).

Results:

Thirty-one subjects with EH and 36 subjects with PA including 22 with aldosterone-producing adenoma (APA) and 14 with idiopathic hyperaldosteronism (IHA) were enrolled in our study. The ADMA levels among the three groups were different (APA 47.83 (27.50, 87.74) ng/ml vs EH 25.08 (22.44, 39.79) ng/ml vs IHA 26.00 (22.23, 33.75) ng/ml; p = 0.04), however, when the APA group was compared with EH and IHA group, there was no statistical significance (47.83 (27.50, 87.74) ng/ml vs 25.08 (22.44, 39.79) ng/ml for EH, p = 0.11; 47.83 (27.50, 87.74) ng/ml vs IHA 26.00 (33.75) ng/ml, p = 0.07). The results of ADMA levels are presented as Median (p25, p75). Whereas, levels of PAI-1 and E-selectin, microvascular endothelial function were not significantly different between PA and EH subjects.

Conclusions:

Our study shows no significant differences between PA and EH in terms of biomarkers of endothelial dysfunction and microvascular endothelial function. The microvascular endothelial function of PA and EH patients is comparable.

Biological Pathways in Adolescent Aortic Stiffness

Background

Aortic stiffening begins in youth and antedates future hypertension. In adults, excess weight, systemic inflammation, dyslipidemia, insulin resistance, neurohormonal activation, and altered adipokines are implicated in the pathogenesis of increased aortic stiffness. In adolescents, we assessed the relations of comprehensive measures of aortic stiffness with body mass index (BMI) and related but distinct circulating biomarkers.

Methods and Results

A convenience sample of 246 adolescents (mean age, 16±2 years; 45% female, 24% Black, and 43% Hispanic) attending primary care or preventive cardiology clinics at 2 tertiary hospitals was grouped as normal weight (N=98) or excess weight (N=148, defined as BMI ≥age‐ and sex‐referenced 85th percentile). After an overnight fast, participants underwent anthropometry, noninvasive arterial tonometry, and assays for serum lipids, CRP (C‐reactive protein), glucose, insulin, renin, aldosterone, and leptin. We used multivariable linear regression to relate arterial stiffness markers (including carotid‐femoral pulse wave velocity) to BMI z score and a biomarker panel. Carotid‐femoral pulse wave velocity was higher in excess weight compared with normal weight group (5.0±0.7 versus 4.6±0.6 m/s; P<0.01). After multivariable adjustment, carotid‐femoral pulse wave velocity was associated with BMI z score (0.09 [95% CI, 0.01–0.18]; P=0.04) and with low‐density lipoprotein cholesterol (0.26 [95% CI, 0.03–0.50]; P=0.03).

Conclusions

Higher BMI and low‐density lipoprotein cholesterol were associated with greater aortic stiffness in adolescents. Maintaining optimal BMI and lipid levels may mitigate aortic stiffness.

An updated pharmacological insight of resveratrol in the treatment of diabetic nephropathy

As one of the most common complications of diabetes, nephropathy develops in approximately 40% of diabetic individuals. Although end stage kidney disease is known as one of the most consequences of diabetic nephropathy, the majority of diabetic individuals might die from cardiovascular diseases and infections before renal replacement treatment. Moreover, the routine medical treatments for diabetes hold undesirable side effects. The explosive prevalence of diabetes urges clinicians and scientists to investigate the complementary or alternative therapies. Phytochemicals are emerging as alternatives with a wide range of therapeutic effects on various pathologies, including diabetic kidney disease. Of those phytochemicals, resveratrol, a natural polyphenolic stilbene, has been found to exert a broad spectrum of health benefits via various signaling molecules. In particular, resveratrol has gained a great deal of attention because of its anti-oxidative, anti-inflammatory, anti-diabetic, anti-obesity, cardiovascular-protective, and anti-tumor properties. In the renal system, emerging evidence shows that resveratrol has already been used to ameliorate chronic or acute kidney injury. This review critically summarizes the current findings and molecular mechanisms of resveratrol in diabetic renal damage. In addition, we will discuss the adverse and inconsistent effects of resveratrol in diabetic nephropathy. Although there is increasing evidence that resveratrol affords great potential in diabetic nephropathy therapy, these results should be treated with caution before its clinical translation. In addition, the unfavorable pharmacokinetics and/or pharmacodynamics profiles, such as poor bioavailability, may limit its extensive clinical applications. It is clear that further research is needed to unravel these limitations and improve its efficacy against diabetic nephropathy. Increasing investigation of resveratrol in diabetic kidney disease will not only help us better understand its pharmacological actions, but also provide novel potential targets for therapeutic intervention.

The mineralocorticoid receptor-an emerging player in metabolic syndrome?

Metabolic syndrome is a cluster of conditions that increase the risk of cardiovascular diseases, and comprises obesity, hypertension, impaired glucose metabolism and dyslipidaemia. It is well recognised that the mineralocorticoid receptor (MR) plays an important role in blood pressure regulation via its effect on salt and water retention in renal tubules, with hypertension being a key feature in primary aldosteronism patients with excess adrenal production of aldosterone, the primary ligand for MRs in the epithelial tissues. MRs are also expressed in a number of non-epithelial tissues including adipose tissue; in these tissues, glucocorticoids or cortisol can also activate MRs due to low levels of 11-beta-hydroxysteroid-dehydrogenase type 2 (11-βHSD2), the enzyme which inactivates cortisol. There is increasing evidence suggesting that over-activation of MRs plays a role in the pathophysiology of the other components of metabolic syndrome, promoting adiposity, inflammation and glucose intolerance, and that MR antagonists may confer beneficial effects on energy and substrate homeostasis and cardiometabolic diseases. This review discusses the advances in the literature shedding light on the MR as an emerging player in metabolic syndrome.

The renin-angiotensin-aldosterone system: a crossroad from arterial hypertension to heart failure

The renin-angiotensin-aldosterone system (RAAS) plays a pivotal role in the regulation of blood pressure and volume homeostasis, promoting critical structural changes in every component of the cardiovascular system, including the heart and blood vessels. Consequently, the RAAS is a crucial therapeutic target for several chronic diseases of the cardiovascular system, spanning from arterial hypertension (AH) to heart failure (HF). AH represents a leading risk factor for the development of symptomatic HF, particularly with left ventricle (LV) preserved ejection fraction (HFpEF). LV diastolic dysfunction and cardiac remodelling are the first discernible manifestations of heart disease in patients with AH. Typically, AH develops many years before the diagnosis of overt HF, providing a therapeutic target for preventive strategies. Treatment of AH is based on different classes of antihypertensive drugs, which show differences in their capacity to prevent the evolution towards HF. The blockers of the RAAS are effective drugs to treat AH and prevent HF with reduced ejection fraction (HFrEF), but the evidence of the potential benefits in patients with HFpEF remains limited. In this review, the authors summarise data from several clinical trials of HFpEF and HFrEF, focusing on the mechanisms leading the transition from AH to HF and late complications.

Is primary aldosteronism a potential risk factor for aortic dissection? A case report and literature review

BACKGROUND

Primary aldosteronism (PA) increases the risk of cardiovascular morbidity, including stroke, coronary artery disease, atrial fibrillation, and heart failure. The relationship between primary aldosteronism and aortic dissection has rarely been reported. We report a case of aortic dissection caused by secondary hypertension from PA and review similar cases in the literature.

CASE PRESENTATION

A 56-year-old woman with a history of surgery for aortic dissection presented for follow-up of hypertension and a left adrenal mass. She had been diagnosed with hypertension and hypokalemia in 2003. Blood pressure had been controlled by antihypertensive medications. In 2009, she presented with chest and back pain; she was diagnosed with aortic dissection by computed tomography (CT). She underwent placement of an endovascular aortic stent graft. CT at that time showed a left adrenal mass with a diameter of 1 cm. In 2017, CT reexamination revealed that the left adrenal mass had grown to 3 cm in diameter. Laboratory data showed blood potassium 2.4 mmol/L (reference range: 3.5-5.3 mmol/L). The plasma aldosterone/renin ratio was elevated because of suppressed plasma renin and elevated serum aldosterone levels. Plasma aldosterone levels were not suppressed after taking captopril. Positron emission tomography/CT showed that the left adrenal tumor radiographic uptake was slightly increased (maximum standardized uptake value of 2.2), and metastasis was not detected. Laparoscopic adrenalectomy was performed, and an adrenocortical adenoma was confirmed histopathologically. After surgery, blood pressure and laboratory findings were within their reference ranges without any pharmacological treatment.

CONCLUSIONS

Our patient and the literature suggest that PA is a potential cause of aortic dissection. Diagnosing PA in the early stages of the disease and early treatment are important because affected patients may be at increased risk of aortic dissection.

Effect of sample delivery conditions on Renin-Angiotensin-Aldosterone System (RAAS) assay

Renin-Angiotensin-Aldosterone System (RAAS) measurements are influenced by several factors. We investigated the effect of sample delivery conditions on RAAS measurements including sample storage temperature and time. Blood samples were collected from thirty participants using enzyme inhibitor tubes and serum separation gel evacuated tubes. Plasma and serum from fresh blood samples without further storage (as baseline), and from blood samples that were stored at either 0 °C, 4 °C, or 25 °C for 3 h, 6 h and 24 h, respectively, were extracted and stored at -30 °C for batch measurements using radioimmunoassay. Concentrations of Aldosterone (Ald) decreased following delivery temperature and time, and were significantly different when samples were set aside at 0 °C for 24 h (p < .01), 4 °C for 6 h (p < .01), and 25 °C for 3 h (p < .05). However, levels of Angiotensin (Ang I) increased following delivery temperature and time, and were significantly different when samples were set aside at 0 °C and 4 °C for 6 h (p < .05) and at 25 °C for 3 h (p < .001). However, no changes were observed for the concentrations of plasma renin activity (PRA) and Ang II, except for Ang II which increased significantly when samples were set aside at 25 °C for 24 h (p < .001). Our results indicate that samples used for RAAS measurement should be placed at a low temperature and analyzed as soon as possible after collection.

Aldosterone renin ratio and chronic kidney disease

As a component of the metabolic syndrome, hypertension (HTN) is increasing throughout the world with variable percentages, but mostly among developing world. Aldosterone plays a role in the relationship between aldosterone and nephropathy. We aimed to evaluate the relationship between aldosterone renin ratio (ARR) and chronic kidney disease (CKD). Variables drawn from the computerized hospital information database were all patients who had an ARR above 35 (if aldosterone reading was above 300 pmol/L). A total of 1584 patients, of whom 777 were male and 807 were female, with a mean [standard deviation (SD)] of 43.3 (16.5) years were studied. The mean ARR was 210.1 (SD: 246.4) in males and 214.3 and 210.1 in females, P = 0.51. The mean estimated glomerular filtration rate (eGFR) was 50.2 (SD 12.6); in males, it was 49.99 (0.90) and in females, it was 50.48 (0.92), P = 0.70. The regression model revealed a negative relationship between ARR and GFR with a coefficient of -2.08, 95% confidence interval: -4.6, 0.21, P = 0.07. CKD population with HTN tends to have a very high level of ARR, and those with advanced CKD have higher ARR. However, high ARR could have low eGFR and kidney dysfunction on follow-up. In view of high prevalence of noncommunicable disease and high early CKD population, there is an important need to consider comprehensive management strategies that involve the blockage of high renin-angiotensin-aldosterone and the use of mineralocorticosteroid receptor blockers.

Aerobic Exercise Training and Nontraditional Cardiovascular Risk Factors in Hemodialysis Patients: Results from a Prospective Randomized Trial

Introduction: Chronic kidney disease (CKD) patients have a high incidence of cardiovascular diseases (CVD) which increases their morbidity and mortality. A sedentary lifestyle in CKD is directly linked to the onset of CVD. Physical activity can bring beneficial effects to CKD patients. Aims: The aim of this study was assess the impact of aerobic training on nontraditional cardiovascular risk factors in CKD patients on hemodialysis. Materials and Methods: This is a prospective, controlled, and randomized clinical trial with analysis of intention to treat. Thirty patients underwent an exercise treadmill test, an arterial stiffness evaluation, echocardiography and analysis of endothelial reactivity, and carotid ultrasound and laboratorial tests, including analysis of serum aldosterone. The intervention group (IG) (n =15) underwent aerobic exercise during hemodialysis 3 times a week for 4 months. The control group (CG) (n =15) had no intervention. All of the patients were reassessed after 4 months. Results: In the IG, there was a statistically significant improvement in flow-mediated vasodilation (FMV; p = 0.002) and a reduction in left ventricular hypertrophy (p = 0.006) and serum aldosterone (p = 0.016). There was an increase in C-reactive protein in the CG (p = 0.002). Conclusion: This aerobic training protocol was able to improve endothelial function with enhanced FMV and reduce left ventricular hypertrophy and serum aldosterone, which could have a positive impact on the reduction of nontraditional cardiovascular risk factors in CKD patients on hemodialysis.

Short- and long-term results of laparoscopic adrenalectomy for Conn's syndrome

Introduction

The primary treatment of Conn’s syndrome (CS) is laparoscopic adrenalectomy and aims to normalize arterial blood pressure and biochemical parameters.

Aim

To analyse short- and long-term results of laparoscopic adrenalectomy for Conn’s syndrome (CS).

Material and methods

The analysis included 44 consecutive patients, who underwent laparoscopic adrenalectomy between 2004 and 2015 for CS. We analysed short- and long-terms results of operations. All patients were followed up 6 and 24 months after surgery to determine changes in the biochemical parameters, and clinical regression of arterial hypertension. We also evaluated the aldosteronoma resolution score (ARS) in predicting the resolution of hypertension.

Results

No conversions were needed. Complications occurred in 5 (11.4%) patients. Preoperative hypokalaemia and hypernatraemia were present in 83.4% and 15.8% of patients, respectively. After surgery, both hypokalaemia and hypernatraemia resolved in all patients. At the follow-up 6 months after the surgery, only 11.3% of patients had complete remission (CR) of hypertension. In 43.2% of cases we observed partial remission (PR). After 24 months CR was found in 13.6% of patients, 45.5% patients fulfilled criteria for PR, and 29.5% of patients changed the group of remission comparison to the first follow-up visit. Only 50% of patients with an ARS of 4 or 5 points achieved CR 6 months after surgery.

Conclusions

Laparoscopic adrenalectomy is a safe method of treatment for CS. Although it effectively eliminates electrolyte imbalance, it does not allow for the CR of hypertension in the majority of patients, especially in the elderly group. We did not find ARS to be an effective tool in predicting postoperative resolution of hypertension.

Aldosterone is involved in the pathogenesis of obesity-related glomerulopathy through activation of Wnt/β-catenin signaling in podocytes

Obesity-related glomerulopathy (ORG) is morphologically characterized by glomerulomegaly with or without observable focal segmental glomerulosclerosis under light microscope, with decreased podocyte density and number, and with increased foot‑process width observed under electron microscope. The severity of podocyte injury is correlated with the degree of proteinuria and renal dysfunction. However, the pathogenesis of ORG is not well understood. The aim of the present study was to explore the possible pathogenic role of aldosterone (ALDO) in ORG. In the in vivo animal experiments, body weight, Lee's obesity index, abdominal fat index, urinary protein excretion, average glomerular diameter were significantly increased, the mRNA and protein expression of podocyte‑associated molecules including nephrin, podocin, podoplanin and podocalyxin were significantly reduced, and the Wnt/β‑catenin signaling pathway was activated in ORG model mice compared with the Control mice, whereas the administration of spironolactone significantly ameliorated these effects. In the in vitro experiments on cultured podocytes, the mRNA and protein expression levels of the aforementioned podocyte‑associated molecules were significantly downregulated and the Wnt/β‑catenin signaling pathway was activated following ALDO stimulation, whereas eplerenone significantly attenuated all the above effects. Dickkopf‑related protein 1 (DKK1), an inhibitor of Wnt/β‑catenin signaling pathway, also reduced the effects of ALDO exposure on the expression of podocyte‑associated molecules. The present study hypothesized that ALDO may be involved in the pathogenesis of ORG through the activation of Wnt/β‑catenin signaling pathway in podocytes.