Mineralocorticoid receptor-associated hypertension and its organ damage: clinical relevance for resistant hypertension

Mineralocorticoid receptor overactivation in diabetes mellitus: role of O-GlcNAc modification

Hypertension is a significant risk factor for microangiopathy and cardiovascular complications in diabetic patients. The efficacy of mineralocorticoid receptor (MR) antagonists in impeding the advancement of diabetic nephropathy, along with the reduction in active renin concentration observed in diabetic retinopathy, strongly implies the involvement of MR overactivation in diabetic complications. This review provides a comprehensive review of various mechanisms proposed for MR overactivation in diabetes mellitus. In particular, it focuses on post-translational MR modifications, including O-linked N-acetylglucosamine modification and phosphorylation, which have been implicated in MR protein stabilization and overactivation under conditions of high glucose. Given the role of MR overactivation in hyperglycemia, it emerges as a promising therapeutic target for preventing diabetic complications. Post-translational modifications (PTMs), such as O-GlcNAcylation and phosphorylation, are related to MR overactivation in diabetes and metabolic syndrome. Aldosterone binding promotes the proteasomal degradation of MR. Under conditions of high glucose, O-GlcNAcylation, and PKCβ-mediated MR phosphorylation are increased. Salt loading and oxidative stress also increase MR phosphorylation through the EGER/ERK pathway. PTMs inhibit ubiquitin attachment to the MR and interfere with the receptor's aldosterone-induced proteasomal degradation. Consequently, they increase the sensitivity of the MR to aldosterone and exacerbate aldosterone-associated complications.

Prevalence of unilateral hyperaldosteronism in primary aldosteronism: impact of a novel chemiluminescent immunoassay for measuring plasma aldosterone in Japan

This study aims to evaluate the prevalence of unilateral hyperaldosteronism (UHA) and its clinical characteristics in patients with primary aldosteronism (PA), diagnosed using plasma aldosterone concentration (PAC) measured by chemiluminescent enzyme immunoassay (CLEIA). We retrospectively analyzed data of 199 PA patients from the Japan Primary Aldosteronism Study II (JPAS II) dataset, including patients who underwent adrenal venous sampling (AVS) and the captopril challenge test (CCT) and/or saline infusion test (SIT), with PAC measured by CLEIA. We focused on two categories: confirmed PA, where patients exhibit clear biochemical evidence of the disorder, and borderline PA, where patients present with marginal biochemical indicators, as outlined in the Japan Endocrine Society's clinical practice guideline for the diagnosis and management of PA. In confirmed PA cases, over the half of patients was UHA, while approximately 15 to 20% of borderline cases were found to be UHA. The prevalence of hypokalemia was identified as predictor of UHA among borderline cases. Among borderline cases with no hypokalemia and adrenal nodules on CT imaging, only 6 to 8% of patients were found to have UHA. Notably, some patients exhibited UHA despite negative results on one test but confirmed result on the other, particularly those with hypokalemia or adrenal nodules on CT imaging. In conclusion, the findings validate the importance of AVS in confirmed PA cases and the need for careful assessment in borderline cases. When feasible, conducting both CCT and SIT, and interpreting their results alongside other clinical indicators, could provide a more comprehensive assessment.

Screening and diagnosis of primary aldosteronism. Consensus document of all the Spanish Societies involved in the management of primary aldosteronism

Primary aldosteronism (PA) is the most frequent cause of secondary hypertension (HT), and is associated with a higher cardiometabolic risk than essential HT. However, PA remains underdiagnosed, probably due to several difficulties clinicians usually find in performing its diagnosis and subtype classification. The aim of this consensus is to provide practical recommendations focused on the prevalence and the diagnosis of PA and the clinical implications of aldosterone excess, from a multidisciplinary perspective, in a nominal group consensus approach by experts from the Spanish Society of Endocrinology and Nutrition (SEEN), Spanish Society of Cardiology (SEC), Spanish Society of Nephrology (SEN), Spanish Society of Internal Medicine (SEMI), Spanish Radiology Society (SERAM), Spanish Society of Vascular and Interventional Radiology (SERVEI), Spanish Society of Laboratory Medicine (SEQC(ML)), Spanish Society of Anatomic-Pathology, Spanish Association of Surgeons (AEC).

Prediction of endogenous mineralocorticoid receptor activity by depressor effects of mineralocorticoid receptor antagonists in patients with primary aldosteronism

Patients with primary aldosteronism have an increased risk of developing cardiovascular disease. The response to mineralocorticoid receptor antagonists varies among individuals, indicating diverse mineralocorticoid receptor activities in these patients. This study explored the factors linked to the efficacy of blood pressure reduction through mineralocorticoid receptor antagonists in patients with primary aldosteronism. We examined the relationship between the reduction in blood pressure and patient characteristics in a group of 41 patients with primary aldosteronism (24 males, mean age 55 ± 13 years, including 34 patients diagnosed with bilateral primary aldosteronism) before and after undergoing treatment with mineralocorticoid receptor antagonists. Significant reductions in office blood pressure were observed 3 and 6 months after treatment initiation. Single correlation analyses showed that the urinary chloride-to-potassium ratio displayed the strongest positive association with blood pressure reduction, surpassing plasma aldosterone concentration, plasma renin activity, and urinary sodium-to-potassium ratio, at 3 and 6 months. Multiple correlation analyses revealed a consistent and independent positive correlation between the urinary chloride-to-potassium ratio and blood pressure reduction at 3 and 6 months. The optimal threshold for the urinary chloride-to-potassium ratio with respect to its ability to lower blood pressure, was determined as 3.18. These results imply that the urinary chloride-to-potassium ratio may be independently associated with the effectiveness of blood pressure reduction facilitated by mineralocorticoid receptor antagonists. Moreover, it could potentially serve as a valuable predictor of the effectiveness of these agents and function as an indicator of endogenous mineralocorticoid receptor activity in patients with primary aldosteronism.

Exposure-response analysis of the efficacy and safety of esaxerenone, a novel nonsteroidal mineralocorticoid receptor blocker, in hypertensive patients with or without diabetic kidney disease

BACKGROUND

Esaxerenone is a novel non-steroidal mineralocorticoid receptor blocker. Here, we assessed efficacy and safety exposure-response relationships of esaxerenone and its covariates and thereby justified the recommended dosage regimens, focusing on the safety benefits of up-titration regimen in patients at higher risk for increased serum potassium (sK+).

METHODS

The relationships between model-derived individual esaxerenone exposure and efficacy (blood pressure [BP]) and safety (increased sK+) were evaluated using multivariate linear regression and Cox regression analyses, respectively, using data from 1453 hypertensive patients with or without diabetic kidney disease in five clinical studies.

RESULTS

Exposure-efficacy analyses demonstrated that higher exposure was linearly associated with greater BP reduction over the investigated dose range. Exposure-safety analyses showed that higher exposure was associated with a higher risk of increased sK+ under a fixed-dosing regimen; higher baseline sK+ and lower baseline estimated glomerular filtration rate (eGFR) were influential covariates. Model-based simulations suggested that fewer occurrences of increased sK+ are expected under the up-titration regimen (from 1.25 to 5 mg) relative to the fixed-dosing regimen (5 mg) in patients with different combinations of these covariates.

CONCLUSIONS

The exposure-response analyses supported the esaxerenone recommended doses and the safety benefits of using the up-titration regimen.

Renoprotective Effects of Mineralocorticoid Receptor Antagonists Against Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a growing epidemic worldwide and a leading cause of end-stage kidney disease. Mineralocorticoid receptor (MR) blockade using Finerenone is a recently approved therapeutic approach to slow down the progression of DKD in patients with type 2 diabetes in addition to other therapies such as angiotensin-II converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), sodium-glucose co-transporter 2 (SGLT2) inhibitors, and glucagon-like peptide 1 (GLP-1) analogs. This review elaborates on the pathophysiologic pathways activated by aldosterone (the human mineralocorticoid) in DKD, the pharmacology of three different generations of mineralocorticoid receptor antagonists (MRAs), specifically, spironolactone, eplerenone, and finerenone, and the mechanisms by which these MRAs elicit their protective effects on the kidney under diabetic settings.

Effects of esaxerenone on blood pressure, urinary albumin excretion, serum levels of NT-proBNP, and quality of life in patients with primary aldosteronism

Primary aldosteronism (PA) is typically managed with mineralocorticoid receptor antagonists (MRAs) barring adrenalectomy. The efficacy of esaxerenone, a nonsteroidal MRA, were explored in patients with PA. Various parameters such as the urinary albumin to creatinine ratio (UACR) and serum levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) were evaluated in 25 PA patients before and 3 and 6 months after esaxerenone treatment. Systolic and diastolic blood pressure (BP), and the estimated glomerular filtration rate decreased after treatment, while serum levels of potassium and active renin increased. Significant reductions were observed in UACR 3 and 6 months after treatment. A significant decrease in NT-proBNP was evident at 6 months but not 3 months after treatment. Correlation analysis indicated that the reductions in BP and UACR at 3 months were independent of estimated daily salt intake. Furthermore, the effect of esaxerenone treatment on lowering UACR and NT-proBNP levels was independent of BP reduction. Responders whose systolic BP decreased 6 months after esaxerenone treatment by more than 10 mmHg compared to pretreatment had higher pretreatment NT-proBNP and similar UACR before and after treatment when compared with nonresponders. Esaxerenone improved mental, physical, and social quality of life (QOL) 6 months after treatment compared to healthy controls and increased over time. No patients discontinued treatment due to severe hyperkalemia or renal dysfunction. In conclusion, esaxerenone is a safe and effective MRA for PA treatment, offering significant benefits in terms of hypertension, albuminuria, NT-proBNP levels, and QOL improvement. Esaxerenone effectively lowers BP, UACR, and serum levels of NT-proBNP independent of dietary salt intake in mild PA patients. ARC active renin concentration, DBP diastolic blood pressure, MR mineralocorticoid receptor, MRA mineralocorticoid receptor antagonist, NT-proBNP N-terminal pro-brain natriuretic peptide, PA primary aldosteronism, QOL quality of life, SBP systolic blood pressure, SF-36 Medical Outcomes Study 36-Item Short-Form Health Survey, UACR urinary albumin to creatinine ratio.

Associations of Diabetic Retinopathy Severity With High Ambulatory Blood Pressure and Suppressed Serum Renin Levels

CONTEXT

The relationships between serum renin levels, severity of diabetic retinopathy (DR), and 24-hour blood pressure (BP) have not been previously reported.

OBJECTIVE

To explore causes for DR and the relationships of 24-hour ambulatory BP, and hormone levels with the severity of DR.

METHODS

The diabetic patients were classified as having no DR, simple DR, or severe DR (preproliferative DR plus proliferative DR) based on funduscopic examination, and we measured 24-hour BP, serum active renin (ARC), aldosterone (SAC), adrenocorticotropic hormone, and cortisol levels in each group.

RESULTS

Compared to those with no DR or simple DR, patients with severe DR showed significantly higher 24-hour BPs, including daytime and nighttime systolic and diastolic BP levels, independent of diabetic duration and HbA1c levels. The variability of nighttime systolic BP was greater in patients with severe DR than in those with nonsevere DR, although nocturnal BP reduction was similar between the groups. The ambulatory BPs were significantly inversely associated with ARC. The ARC was significantly lower in severe DR patients than in those with no DR or simple DR (3.2 [1.5-13.6] vs 9.8 [4.6-18.0] pg/mL, P < .05), but there were no differences in SAC in patients taking calcium channel blockers and/or α-blockers. No associations were found between DR severity and other hormone levels.

CONCLUSION

Severe DR was associated with higher 24-hour BPs and suppressed ARC. These findings suggest that mineralocorticoid receptor overactivation may play a role in higher BP levels and severe DR in diabetic patients.

Recent understandings about hypertension management in type 2 diabetes: What are the roles of SGLT2 inhibitor, GLP-1 receptor agonist, and finerenone?

Diabetes and hypertension often coexist, with about half of patients with diabetes also having hypertension. The risk of cardiovascular disease increases by three to six-fold with the coexistence of diabetes and hypertension; therefore, the management of blood pressure to prevent cardiovascular disease is a particularly important issue in patients with diabetes. Clinical trial findings have resulted in recommendations to control blood pressure to <130/80 mmHg in Japanese patients with diabetes. However, the target blood pressure and selection of anti-hypertensive medications should vary depending on the duration of diabetes and comorbidities, and guidelines and clinical trial results should be interpreted flexibly to provide anti-hypertensive treatment tailored to individual patients. In recent years, a number of drugs have emerged that have significant cardio-renal protective effects in patients with diabetes, and a typical example is sodium-glucose cotransporter 2 inhibitor (SGLT2i), glucagon-like peptide-1 receptor agonist (GLP-1RA), and nonsteroidal mineralocorticoid receptor antagonist, finerenone. They have also shown modest but significant blood pressure-lowering effects. In the future, beyond considering the thresholds for how far to lower blood pressure, blood pressure management in patients with diabetes will require understanding the additive cardioprotective value of drugs aimed at lowering blood pressure and the quality of blood pressure lowering. Clinical questions of blood pressure lowering in patients with diabetes GLP-1RA, glucagon-like peptide-1 receptor agonist; SGLT2i, sodium-glucose cotransporter 2 inhibitor.

Rationale and design of an investigator-initiated, multicenter, prospective, placebo-controlled, double-blind, randomized trial to evaluate the effects of finerenone on vascular stiffness and cardiorenal biomarkers in type 2 diabetes and chronic kidney disease (FIVE-STAR)

BACKGROUND

The overactivation of mineralocorticoid receptor (MR) plays a key pathological role in the progression of cardiovascular and renal diseases by promoting pro-inflammatory and pro-fibrotic signaling. Recently, it has been found that finerenone, a novel nonsteroidal selective MR antagonist, can robustly improve cardiorenal outcomes in patients with type 2 diabetes (T2D) and a wide spectrum of chronic kidney disease (CKD). However, the mechanisms underlying the cardiorenal benefits of finerenone are poorly understood. Further, whether the clinical benefits are mediated by an improvement in vascular stiffness is not confirmed. Therefore, the current study aims to evaluate the effects of finerenone on vascular stiffness as assessed using cardio ankle vascular index (CAVI) and relevant cardiorenal biomarkers in patients with T2D and CKD.

METHODS

The Effects of Finerenone on Vascular Stiffness and Cardiorenal Biomarkers in Type 2 Diabetes and Chronic Kidney Disease (FIVE-STAR) is an ongoing, investigator-initiated, multicenter, prospective, placebo-controlled, double-blind, randomized clinical trial in Japan. Its target sample size is 100 subjects. Recruitment will be performed from September 2023 to July 2024. After obtaining informed consent, eligible participants with T2D and CKD (25 mL/min/1.73 m² ≤ estimated glomerular filtration ratio [eGFR] < 90 mL/min/1.73 m² and 30 mg/g Cr ≤ urinary albumin-to-creatinine ratio [UACR] < 3500 mg/g Cr) will be equally randomized to receive 24-week treatment with either finerenone (starting dose at 10 mg once daily in participants with a baseline eGFR < 60 mL/min/1.73 m² or at 20 mg once daily in those with a baseline eGFR ≥ 60 mL/min/1.73 m²) or dose-matched placebo. The primary endpoint is the change from baseline in CAVI at 24 weeks. The secondary endpoints are changes from baseline in UACR at 12 and 24 weeks and relevant serum and urinary biomarkers at 24 weeks. As an exploratory endpoint, proteomic analysis using the Olink® Target 96 panels will be also performed.

DISCUSSION

FIVE-STAR is the first trial evaluating the therapeutic impact of finerenone on vascular stiffness and relevant cardiorenal biomarkers in patients with T2D and CKD. This study will provide mechanistic insights on the clinical benefits of finerenone based on recent cardiovascular and renal outcome trials. Trial registration Unique Trial Number, NCT05887817 ( https://clinicaltrials.gov/ct2/show/NCT05887817 ) and jRCTs021230011 ( https://jrct.niph.go.jp/latest-detail/jRCTs021230011 ).

Recent progress in the diagnosis and treatment of primary aldosteronism

Primary aldosteronism (PA) is caused by excessive secretion of aldosterone from the adrenal glands, with subsequent changes in the renin-angiotensin system. In Japan, chemiluminescent enzyme immunoassay is currently performed for aldosterone assay rather than the earlier method of radioimmunoassay. This change in aldosterone measurement methods has resulted in faster and more accurate measurement of blood aldosterone levels. Since 2019, esaxerenone, a mineralocorticoid receptor antagonist (MRA) with a non-steroidal skeleton, has been available in Japan for the treatment of hypertension. Esaxerenone has been reported to have various effects, such as strong antihypertensive and anti-albuminuric/proteinuric effects. Treatment of PA with MRAs has been reported to improve the patient's quality of life and to suppress the onset of cardiovascular events independent of their effects on blood pressure. Measuring renin levels is recommended for monitoring the extent of mineralocorticoid receptor blockade during MRA treatment. Patients receiving MRAs are prone to developing hyperkalemia, and combining MRAs with sodium/glucose cotransporter 2 inhibitors is expected to prevent severe hyperkalemia and provide additional cardiorenal protection. Mineralocorticoid receptor-associated hypertension is a broad concept of hypertension that includes not only PA, but also hypertension caused by borderline aldosteronism, obesity, diabetes, and sleep apnea syndrome. New findings on primary aldosteronism, which is part of MR-associated hypertension. Aldosterone measurements have been changed to the CLEIA method. Treatment of primary aldosteronism with MRAs has a variety of positive effects. CT-guided radiofrequency ablation and transarterial embolization are alternatives to surgery for aldosterone-producing adenomas. BP blood pressure, CLEIA chemiluminescent enzyme immunoassay, CT computed tomography, K serum potassium, MR mineralocorticoid receptor, MRA mineralocorticoid receptor antagonist, QOL quality of life, SGLT2i sodium/glucose cotransporter 2 inhibitor.

Nighttime home blood pressure lowering effect of esaxerenone in patients with uncontrolled nocturnal hypertension: the EARLY-NH study

There is limited evidence on the blood pressure (BP)-lowering effect of esaxerenone on home BP, including nighttime BP. Using two newly developed nocturnal home BP monitoring devices (brachial and wrist), this multicenter, open-label, prospective study investigated the nighttime home BP-lowering effect of esaxerenone in patients with uncontrolled nocturnal hypertension being treated with an angiotensin receptor blocker (ARB) or calcium-channel blocker (CCB). In total, 101 patients were enrolled. During the 12-week study period, change in nighttime home systolic/diastolic BP from baseline to end of treatment measured by the brachial device was -12.9/-5.4 mmHg in the total population and -16.2/-6.6 and -10.0/-4.4 mmHg in the ARB and CCB subcohorts, respectively (all p < 0.001). For the wrist device, the change was -11.7/-5.4 mmHg in the total population and -14.6/-6.2 and -8.3/-4.5 mmHg in each subcohort, respectively (all p < 0.001). Similar significant reductions were shown for morning and bedtime home BP and office BP. Urinary albumin-to-creatinine ratio, N-terminal pro-brain natriuretic peptide, and cardio-ankle vascular index improved in the total population and each subcohort. Incidences of treatment-emergent adverse events (TEAEs) and drug-related TEAEs were 38.6% and 16.8%, respectively; most were mild or moderate. The most frequent drug-related TEAEs were associated with serum potassium elevation (hyperkalemia, 9.9%; blood potassium increased, 3.0%); however, no new safety concerns were raised. Esaxerenone was effective in lowering nighttime home BP as well as morning and bedtime home BP and office BP, safe, and showed organ-protective effects in patients with uncontrolled nocturnal hypertension. Caution is warranted regarding elevated serum potassium levels. This study investigated the effect of esaxerenone on nighttime home BP and organ damage (UACR and NT-proBNP) in patients with uncontrolled nocturnal hypertension despite treatment with an ARB or CCB. Our results show that safe 24-h BP control and organ protection are possible with esaxerenone.

Aldosterone: Essential for Life but Damaging to the Vascular Endothelium

The renin angiotensin aldosterone system is a key regulator of blood pressure. Aldosterone is the final effector of this pathway, acting predominantly via mineralocorticoid receptors. Aldosterone facilitates the conservation of sodium and, with it, water and acts as a powerful stimulus for potassium excretion. However, evidence for the pathological impact of excess mineralocorticoid receptor stimulation is increasing. Here, we discussed how in the heart, hyperaldosteronism is associated with fibrosis, cardiac dysfunction, and maladaptive hypertrophy. In the kidney, aldosterone was shown to cause proteinuria and fibrosis and may contribute to the progression of kidney disease. More recently, studies suggested that aldosterone excess damaged endothelial cells. Here, we reviewed how damage to the endothelial glycocalyx may contribute to this process. The endothelial glycocalyx is a heterogenous, negatively charged layer on the luminal surface of cells. Aldosterone exposure alters this layer. The resulting structural changes reduced endothelial reactivity in response to protective shear stress, altered permeability, and increased immune cell trafficking. Finally, we reviewed current therapeutic strategies for limiting endothelial damage and suggested that preventing glycocalyx remodelling in response to aldosterone exposure may provide a novel strategy, free from the serious adverse effect of hyperkalaemia seen in response to mineralocorticoid blockade.

Mineralocorticoid Receptor Antagonists for Preventing Chronic Kidney Disease Progression: Current Evidence and Future Challenges

Regulation and action of the mineralocorticoid receptor (MR) have been the focus of intensive research over the past 80 years. Genetic and physiological/biochemical analysis revealed how MR and the steroid hormone aldosterone integrate the responses of distinct tubular cells in the face of environmental perturbations and how their dysregulation compromises fluid homeostasis. In addition to these roles, the accumulation of data also provided unequivocal evidence that MR is involved in the pathophysiology of kidney diseases. Experimental studies delineated the diverse pathological consequences of MR overactivity and uncovered the multiple mechanisms that result in enhanced MR signaling. In parallel, clinical studies consistently demonstrated that MR blockade reduces albuminuria in patients with chronic kidney disease. Moreover, recent large-scale clinical studies using finerenone have provided evidence that the non-steroidal MR antagonist can retard the kidney disease progression in diabetic patients. In this article, we review experimental data demonstrating the critical importance of MR in mediating renal injury as well as clinical studies providing evidence on the renoprotective effects of MR blockade. We also discuss areas of future investigation, which include the benefit of non-steroidal MR antagonists in non-diabetic kidney disease patients, the identification of surrogate markers for MR signaling in the kidney, and the search for key downstream mediators whereby MR blockade confers renoprotection. Insights into these questions would help maximize the benefit of MR blockade in subjects with kidney diseases.

Mechanisms of mineralocorticoid receptor-associated hypertension in diabetes mellitus: the role of O-GlcNAc modification

This study investigated the mechanism underlying the beneficial effects of mineralocorticoid receptor (MR) antagonists in patients with resistant hypertension and diabetic nephropathy by examining post-translational modification of the MR by O-linked-N-acetylglucosamine (O-GlcNAc), which is strongly associated with type 2 diabetes. Coimmunoprecipitation assays in HEK293T cells showed that MR is a target of O-GlcNAc modification (O-GlcNAcylation). The expression levels and transcriptional activities of the receptor increased in parallel with its O-GlcNAcylation under high-glucose conditions. Liquid chromatography-tandem mass spectrometry revealed O-GlcNAcylation of the MR at amino acids 295-307. Point mutations in those residues decreased O-GlcNAcylation, and both the protein levels and transcriptional activities of MR. In db/db mouse kidneys, MR protein levels increased in parallel with overall O-GlcNAc levels of the tissue, accompanied by increased SGK1 mRNA levels. The administration of 6-diazo-5-oxo-L-norleucin, an inhibitor of O-GlcNAcylation, reduced tissue O-GlcNAc levels and MR protein levels in db/db mice. Thus, our study showed that O-GlcNAcylation of the MR directly increases protein levels and transcriptional activities of the receptor under high-glucose conditions in vitro and in vivo. These findings provide a novel mechanism of MR as a target for prevention of complications associated with diabetes mellitus.

Reduction of Proteinuria in a Patient With Primary Aldosteronism by Angiotensin II Receptor Blocker Administration

The renin-angiotensin-aldosterone system (RAAS) is a major target for treating hypertension and preventing various complications. Mineralocorticoid receptor (MR) antagonists are recommended as specific drugs to ameliorate hyperactive MR signaling, especially for patients with idiopathic hyperaldosteronism. However, the clinical implications of an increased RAAS activity and angiotensin II level induced by MR antagonist administration remain unclear. A 72-year-old Japanese man was referred to our university hospital for refractory hypertension management. He has also had type 2 diabetes mellitus and nephropathy for 8 years. MR antagonists, initiated based on the diagnosis of primary aldosteronism, effectively improved his hypertension. However, proteinuria of 2.5 g/g creatinine, concomitant with an increase in both active renin concentration and plasma aldosterone concentration, occurred. Additional administration of an angiotensin II receptor blocker successfully reduced the plasma aldosterone concentration and proteinuria (<0.3 g/g creatinine). Preserved renal function was confirmed for 1 year thereafter. In conclusion, this case suggests that the angiotensin II receptor is a potential target to treat proteinuria concomitant with primary aldosteronism. RAAS reactivation should be considered when an MR antagonist is initiated for patients with primary aldosteronism, especially idiopathic hyperaldosteronism.

Nephrons, podocytes and chronic kidney disease: Strategic antihypertensive therapy for renoprotection

Chronic kidney disease (CKD) is one of the strongest risk factors for hypertension, and hypertension can exacerbate the progression of CKD. Thus, the management of CKD and antihypertensive therapy are inextricably linked. Research over the past decades has shown that the human kidney is more diverse than initially thought. Subjects with low nephron endowment are at increased risk of developing CKD and hypertension, which is consistent with the theory of the developmental origins of health and disease. Combined with other lifetime risks of CKD, hypertension may lead to a vicious cycle consisting of podocyte injury, glomerulosclerosis and further loss of nephrons. Of note, recent studies have shown that the number of nephrons correlates well with the number of podocytes, suggesting that these two components are intrinsically linked and may influence each other. Both nephrons and podocytes have no or very limited regenerative capacity and are destined to decrease throughout life. Therefore, one of the best strategies to slow the progression of CKD is to maintain the "numbers" of these essential components necessary to preserve renal function. To this end, both the achievement of an optimal blood pressure and a maximum reduction in urinary protein excretion are essential. Lifestyle modifications and antihypertensive drug therapy must be carefully individualized to address the potential diversity of the kidneys.

Dex modulates the balance of water-electrolyte metabolism by depressing the expression of AVP in PVN

Dexmedetomidine (Dex) is a highly selective α2 adrenergic agonist used in clinical anesthesia. Studies have shown that Dex can act on the collecting duct and reduce the body’s water reabsorption, thereby increasing water discharge. However, the specific mechanism of Dex on water homeostasis remains unclear. The hypothalamus is the regulatory center of water and salt balance and secretes related neurochemical hormones, such as arginine vasopressin (AVP), to regulate the discharge of water and salt. The paraventricular nucleus (PVN) and supraoptic nucleus (SON) in the hypothalamus are also considered to be the key targets of the thirst loop. They are responsible for the secretion of AVP. The suprachiasmatic nucleus (SCN) is also one of the brain regions where AVP neurons are densely distributed in the hypothalamus. This study used C57BL/6J mice for behavior, immunofluorescence, and blood analysis experiments. Our results showed that Dex could not only depress the expression of AVP in the PVN but also reduce serum AVP concentration. The animal water intake was decreased without impairing the difference in food consumption and the urine excretion was enhanced after the intraperitoneal injection of Dex, while AVP supplementation restored the water intake and inhibited the urine excretion of mice in the Dex group. In addition, the renin-angiotensin-aldosterone system is vital to maintaining serum sodium concentration and extracellular volume. We found that serum sodium, serum chloride, serum aldosterone (ALD) concentration, and plasma osmolality were decreased in the Dex group, which inhibited water reabsorption, and the plasma osmolarity of mice in the Dex group supplemented with AVP was significantly higher than that in Dex group. We also found that Dex significantly increased the concentration of blood urea nitrogen and decreased the concentration of creatinine within the normal range of clinical indicators, indicating that there was no substantive lesion in the renal parenchyma. These results showed that Dex could modulate the balance of water-electrolyte metabolism by depressing the expression of AVP in PVN without impairing renal function.

Update on Hypertension Research in 2021

In 2021, 217 excellent manuscripts were published in Hypertension Research. Editorial teams greatly appreciate the authors' contribution to hypertension research progress. Here, our editorial members have summarized twelve topics from published work and discussed current topics in depth. We hope you enjoy our special feature, "Update on Hypertension Research in 2021".

Clinical effect of nonsteroidal mineralocorticoid receptor (MR) antagonists in the treatment of diabetic kidney disease: expectations as a new therapeutic strategy

Diabetes mellitus is the main cause of chronic kidney disease (CKD) in Japan and worldwide. Although angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 receptor blockers (ARBs) are basic drugs for the treatment of CKD with diabetes (diabetic kidney disease, DKD) with albuminuria and/or proteinuria, it has also become clear that the use of an ACE inhibitor or ARB alone is not fully sufficient. We have previously reported the clinical effects of mineralocorticoid receptor (MR) antagonists and recommended their use in addition to renin-angiotensin system inhibitors. Recently, new types of nonsteroidal MR antagonists have been developed, and the results of a large-scale study are expected. Nonsteroidal MR antagonists are distributed in the heart, lungs, liver, and kidneys when administered orally and are characterized by their equivalent distribution between the heart (nonepithelial tissue) and kidneys (epithelial tissue). We summarize the latest evidence regarding the use of nonsteroidal MR antagonists in the treatment of DKD. Hyperkalemia and renal dysfunction are frequent during MR antagonist treatment. However, with careful and combined monitoring of these two conditions, the effectiveness of MR antagonists will not be diminished; conversely, it is apparent that patients at such risk will benefit more from the addition of an MR antagonist to the treatment regimen. The most important measure against hyperkalemia is the regular monitoring of serum potassium levels and renal function. The safest and most reliable measure against hyperkalemia is the combined use of a new oral potassium adsorbent that has high potassium selectivity and few side effects. In DKD treatment, it is important to continue using MR antagonists without interruption as much as possible.

Aldosterone breakthrough from a pharmacological perspective

Aldosterone (Aldo) breakthrough is a well-known phenomenon that occurs in patients with long-term renin-angiotensin aldosterone system (RAAS) blockade using inhibitors of renin or angiotensin converting enzyme or angiotensin II type 1 receptor blockers. The blockade of the mineralocorticoid receptor (MR), an Aldo binding receptor, is effective in managing patients with resistant hypertension, defined as uncontrollable blood pressure despite the concurrent use of three antihypertensive drugs. In other words, MR inhibitors are not used as first-line antihypertensive drugs in most guidelines for hypertension management. Aldo breakthrough puts hypertensive patients at higher risk of cardiovascular disease and worsens future outcomes. This review discusses Aldo secretion and the mechanism of Aldo breakthrough, dependent or independent of the RAAS, with consideration of the pharmacological aspects of this phenomenon, as well as hypothetical views.

The Mineralocorticoid receptor signal could be a new molecular target for the treatment of diabetic retinal complication

BACKGROUND

Activation of the mineralocorticoid receptor (MR) is involved in the pathophysiology of diabetic vascular complications. In recent years, it has been indicated that the MR expressed in retinal Müller cells plays an important role in regulating the potassium and water balance in the retina. Therefore, it has also been speculated that abnormal MR signaling contributes to edematous diseases of the retina.

RESEARCH DESIGN AND METHODS

We examined the effect of high-glucose conditions on MR protein and mRNA levels in human retinal Müller cells and changes in cell size in vitro. We also investigated MR transcriptional activity and signaling in high-glucose conditions.

RESULTS

The MR protein increased by 2.2-fold with high-glucose treatment. Additionally, high-glucose treatment induced Müller cell swelling. Aldosterone-induced MR transcriptional activity was enhanced in high-glucose conditions, resulting in the upregulation of αENaC, AQP4 and Kir4.1 mRNA. Treatment with an MR antagonist led to the suppression of aldosterone-induced cell swelling, MR transcriptional activity and upregulation of the target genes in high-glucose conditions.

CONCLUSIONS

High glucose induces Müller cell swelling through activation of MR signaling, which could be associated with aggravation of macular edema. Thus, Müller cell swelling and diabetic macular edema may represent a target for treatment with MR antagonists.

Japan Endocrine Society clinical practice guideline for the diagnosis and management of primary aldosteronism 2021

Primary aldosteronism (PA) is associated with higher cardiovascular morbidity and mortality rates than essential hypertension. The Japan Endocrine Society (JES) has developed an updated guideline for PA, based on the evidence, especially from Japan. We should preferentially screen hypertensive patients with a high prevalence of PA with aldosterone to renin ratio ≥200 and plasma aldosterone concentrations (PAC) ≥60 pg/mL as a cut-off of positive results. While we should confirm excess aldosterone secretion by one positive confirmatory test, we could bypass patients with typical PA findings. Since PAC became lower due to a change in assay methods from radioimmunoassay to chemiluminescent enzyme immunoassay, borderline ranges were set for screening and confirmatory tests and provisionally designated as positive. We recommend individualized medicine for those in the borderline range for the next step. We recommend evaluating cortisol co-secretion in patients with adrenal macroadenomas. Although we recommend adrenal venous sampling for lateralization before adrenalectomy, we should carefully select patients rather than all patients, and we suggest bypassing in young patients with typical PA findings. A selectivity index ≥5 and a lateralization index >4 after adrenocorticotropic hormone stimulation defines successful catheterization and unilateral subtype diagnosis. We recommend adrenalectomy for unilateral PA and mineralocorticoid receptor antagonists for bilateral PA. Systematic as well as individualized clinical practice is always warranted. This JES guideline 2021 provides updated rational evidence and recommendations for the clinical practice of PA, leading to improved quality of the clinical practice of hypertension.

miR-324-5p and miR-30c-2-3p Alter Renal Mineralocorticoid Receptor Signaling under Hypertonicity

The Mineralocorticoid Receptor (MR) mediates the sodium-retaining action of aldosterone in the distal nephron, but mechanisms regulating MR expression are still poorly understood. We previously showed that RNA Binding Proteins (RBPs) regulate MR expression at the post-transcriptional level in response to variations of extracellular tonicity. Herein, we highlight a novel regulatory mechanism involving the recruitment of microRNAs (miRNAs) under hypertonicity. RT-qPCR validated miRNAs candidates identified by high throughput screening approaches and transfection of a luciferase reporter construct together with miRNAs Mimics or Inhibitors demonstrated their functional interaction with target transcripts. Overexpression strategies using Mimics or lentivirus revealed the impact on MR expression and signaling in renal KC3AC1 cells. miR-324-5p and miR-30c-2-3p expression are increased under hypertonicity in KC3AC1 cells. These miRNAs directly affect Nr3c2 (MR) transcript stability, act with Tis11b to destabilize MR transcript but also repress Elavl1 (HuR) transcript, which enhances MR expression and signaling. Overexpression of miR-324-5p and miR-30c-2-3p alter MR expression and signaling in KC3AC1 cells with blunted responses in terms of aldosterone-regulated genes expression. We also confirm that their expression is increased by hypertonicity in vivo in the kidneys of mice treated with furosemide. These findings may have major implications for the pathogenesis of renal dysfunctions, sodium retention, and mineralocorticoid resistance.

Re-Assessment of the Oral Salt Loading Test Using a New Chemiluminescent Enzyme Immunoassay Based on a Two-Step Sandwich Method to Measure 24-Hour Urine Aldosterone Excretion

Since April 2021, the plasma aldosterone concentration has been measured by chemiluminescent enzyme immunoassay (CLEIA) in Japan. In the present study, we developed a new CLEIA using a two-step sandwich method to measure the 24-hour urine aldosterone level. We collected 115 urine samples and measured 24-hour urine aldosterone levels employing radioimmunoassay (RIA), CLEIA, and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results showed that the 24-hour urine aldosterone levels measured using CLEIA and LC-MS/MS were significantly correlated (ρ = 0.992, P < 0.0001). Based on the results of Passing-Bablok regression analysis, the slope was 0.992 and the intercept -19.3. The 24-hour urine aldosterone levels measured using CLEIA and RIA were also significantly correlated (ρ = 0.905, P < 0.0001). However, the aldosterone level measured by CLEIA was lower than that measured by RIA (slope, 0.729; intercept, 120.9). In Japan, a new guideline for primary aldosteronism has been announced, with changes in the aldosterone measurement method. The cutoff values for oral sodium loading test (OSLT) were changed, but clinical verification using real-world urine samples has not been performed. Therefore, we examined the cut-off value of the 24-hour urine aldosterone level after the OSLT. Receiver operating characteristic analysis revealed a cut-off value for primary aldosteronism of 3 μg/day.

Lysine-specific demethylase 1 as a corepressor of mineralocorticoid receptor

Mineralocorticoid receptor (MR) and its ligand aldosterone play a central role in controlling blood pressure by promoting sodium reabsorption in the kidney. Coregulators are recruited to regulate the activation of steroid hormone receptors. In our previous study, we identified several new candidates for MR coregulators through liquid chromatography-tandem mass spectrometry analysis using a biochemical approach. Lysine-specific demethylase 1 (LSD1) was identified as a candidate. The relationship between LSD1 and salt-sensitive hypertension has been reported; however, the role of MR in this condition is largely unknown. Here, we investigated the functions of LSD1 as a coregulator of MR. First, a coimmunoprecipitation assay using HEK293F cells showed specific interactions between MR and LSD1. A chromatin immunoprecipitation study demonstrated LSD1 recruitment to the gene promoter of epithelial Na⁺ channel (ENaC), a target gene of MR. Reduced LSD1 expression by treatment with shRNA potentiated the hormonal activation of ENaC and serum/glucocorticoid-regulated kinase 1, another target gene of MR, indicating that LSD1 is a corepressor of MR. In an animal study, mice with kidney-specific LSD1 knockout (LSD1^flox/floxKSP-Cre mice) developed hypertension after a high-salt diet without elevation of aldosterone levels, which was counteracted by cotreatment with spironolactone, an MR antagonist. In conclusion, our in vitro and in vivo studies demonstrated that LSD1 is a newly identified corepressor of MR.

“Greedy Organs Hypothesis” for sugar and salt in the pathophysiology of non-communicable diseases in relation to sodium-glucose co-transporters in the intestines and the kidney

Deposition of visceral fat and insulin resistance play central role in the development of non-communicable diseases (NCDs) including obesity, hypertension and type 2 diabetes. However, we shed more light upon the intestines and the kidney as a strong driver of NCDs. Based upon unexpected outcomes of clinical trials using sodium-glucose cotransporter (SGLT) 2 inhibitors to demonstrate their actions for not only body weight reduction and blood glucose fall but also remarkable cardiorenal protection, we speculate that hyperfunction of the intestines and the kidney is one of critical contributing factors for initiation of NCDs. By detecting high amount of glucose and sodium chloride around them by sweet/salt taste sensors, the intestines and the kidney are designed to (re)absorb these nutrients by up-regulating SGLT1 or SGLT2. We designate these hyperfunctioning organs for nutrient uptake as “greedy organs”. The greedy organs can induce NCDs (“greedy organ hypothesis”). SGLTs are regulated by glucose and sodium chloride, and SGLTs or other genes can be “greedy genes.” Regulating factors for greedy organs are renin-angiotensin system, renal sympathetic nervous activity, gut inflammation/microbiota or oxidative stress. Mitigation of organ greediness by SGLT2 inhibitors, ketone bodies, bariatric surgery, and regular lifestyle to keep rhythmicity of biological clock are promising.

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We propose the concept of “Greedy Organs” hypothesis as a possible cause of NCDs.

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Clinical implication of greedy kidney is supported by the effect of SGLT2 inhibitors.

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The significance of greedy intestines is suggested by the effect of bariatric surgery.

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The intestines and kidney become hyperactive through upregulation of SGLT1 or 2.

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To mitigate “greedy organs” should be a promising strategy against NCDs.

The mineralocorticoid receptor blocker spironolactone lowers plasma interferon-γ and interleukin-6 in patients with type 2 diabetes and treatment-resistant hypertension

BACKGROUND

The mineralocorticoid receptor antagonist spironolactone lowers blood pressure in patients with resistant hypertension despite antihypertensive treatment with angiotensin-converting inhibitors (ACEi) and angiotensin-II receptor blockers (ARB). In preclinical studies, spironolactone suppresses pro-hypertensive interleukin 17A (IL-17A).

OBJECTIVES

Plasma samples were analysed from a randomized, double-blind placebo-controlled trial with spironolactone given to patients with type 2 diabetes mellitus (T2DM) and resistant hypertension on three antihypertensive drugs. We tested the hypothesis that spironolactone-induced antihypertensive effects are associated with suppression of IL-17A and related cytokines.

METHODS

Interferon-γ (IFN-γ), IL-17A, tumor necrosis factor-α (TNF-α), IL-6, IL-1β and IL-10 were assessed in plasma with immunoassay in samples before and after 16 weeks of treatment with placebo or spironolactone (12.5-25-50 mg/day).

RESULTS

Spironolactone significantly reduced plasma IFN-γ and IL-6 while IL-17A, TNF-α, IL-1β and IL-10 were unchanged. IL-6 was more sensitive to higher doses of spironolactone. At baseline, serum aldosterone correlated positively with diastolic night blood pressure. Urine albumin/creatinine-ratios correlated positively with plasma IL-6 at baseline. There were no relations between aldosterone and cytokine concentrations at baseline; between cytokine concentration and blood pressure at baseline; and between cytokine concentration decrease and blood pressure decrease, except for IFN-γ, after treatment. The spironolactone-induced elevation in plasma potassium related inversely to blood pressure but not to changes in cytokines. In macrophages in vitro, spironolactone suppressed lipopolysaccharide (LPS)-induced TNF-α, IL-6, IL-1β and IL-10 levels.

CONCLUSION

The antihypertensive action of spironolactone in resistant hypertensive patients is associated with suppressed IFN-γ and IL-6 and not IL-17A. Spironolactone exerts anti-inflammatory actions in vivo on macrophages and T-cells.

Safety and efficacy of esaxerenone in Japanese hypertensive patients with heart failure with reduced ejection fraction: A retrospective study

Esaxerenone, a mineralocorticoid receptor blocker (MRB), is a new antihypertensive agent. However, esaxerenone-related data with respect to hypertension with heart failure are limited. We investigated the safety and efficacy of esaxerenone in hypertensive patients with heart failure with reduced ejection fraction (HFrEF). Hypertensive patients with HFrEF treated with esaxerenone were retrospectively analyzed at two timepoints (short-term: 35±15 days; mid-term: 167±45 days). Adverse events including hyperkalemia (K⁺ >5.5 mEq/L), worsening renal function (WRF; estimated glomerular filtration rate (eGFR) reduction by ≥20%), and hypotension (systolic blood pressure <90 mmHg) were evaluated. eGFR and K⁺, serum creatinine, and brain natriuretic peptide (BNP) levels at baseline, short-term, and mid-term assessments were compared. Patients administered esaxerenone as their first MRB (first-MRB cohort) and those who converted from another MRB (conversion cohort) were separately analyzed. There were 50 (56±10 years old, 26% female) patients. At the short-term assessment, hyperkalemia or hypotension was not observed at a dose of 2.0±0.9 mg/day. Seven patients (14%) showed WRF. K⁺ was slightly elevated (4.12±0.41 to 4.25±0.39 mmol/L, p = 0.07) and eGFR was significantly reduced (66.9±19.6 mL/min/1.73 m² to 62.4±19.7 mL/min/1.73 m², p = 0.006). In the conversion cohort, significant changes in K⁺ and eGFR from baseline were not observed at the short-term assessment. BNP levels were consistently improved regardless of the cohorts (first-MRB cohort, 310 [110–370] pg/mL to 137 [47–152] pg/mL, p = 0.001; conversion cohort, 181 [30–203] pg/mL to 108 [26–146] pg/mL, p = 0.028). At the mid-term assessment, there were no significant changes in K⁺ and eGFR compared with the short-term assessment. In conclusion, esaxerenone was safe for hypertensive patients with HFrEF. Hyperkalemia and hypotension were rarely noted, while eGFR was marginally reduced. Moreover, esaxerenone might be beneficial for HFrEF in terms of BNP level reduction.

Effect of the Nonsteroidal Mineralocorticoid Receptor Blocker, Esaxerenone, on Nocturnal Hypertension: A Post Hoc Analysis of the ESAX-HTN Study

BACKGROUND

Nocturnal hypertension is an important phenotype of abnormal diurnal blood pressure (BP) variability and a known risk marker for target organ damage and cardiovascular events. This study aimed to assess the differential BP-lowering effects of esaxerenone vs. eplerenone on nocturnal BP in hypertensive patients with different nocturnal dipping patterns.

METHODS

This was a post hoc analysis of the "Esaxerenone (CS-3150) Compared to Eplerenone in Patients with Essential Hypertension" study (NCT02890173), which was a phase 3, multicenter, randomized, controlled, double-blind, parallel-group clinical study conducted in Japan. Ambulatory BP monitoring data were collected.

RESULTS

Patients (n = 1,001) were randomized to esaxerenone 2.5 mg/day (n = 331) or 5 mg/day (n = 338), or eplerenone 50 mg/day (n = 332). Reductions in nighttime systolic BP (95% confidence interval) were significantly greater with 2.5 and 5 mg/day esaxerenone vs. eplerenone (-2.6 [-5.0, -0.2] and -6.4 mm Hg [-8.8, -4.0], respectively). Esaxerenone significantly reduced nighttime BP from baseline compared with eplerenone in non-dippers with previously uncontrolled BP. In addition, esaxerenone did not markedly alter nighttime BP in extreme dipper patients. In the esaxerenone 5 mg/day group, esaxerenone-induced decreases in nighttime BP were greater than eplerenone-induced decreases in older patients.

CONCLUSIONS

Esaxerenone may be an effective treatment option for nocturnal hypertension, especially in older patients and those with a non-dipper pattern of nocturnal BP.

A systematic review and meta-analysis of effects of spironolactone on blood pressure, glucose, lipids, renal function, fibrosis and inflammation in patients with hypertension and diabetes

PURPOSE

Hypertension commonly co-exists with diabetes mellitus (DM), and both are closely related to adverse health outcomes. The activation of aldosterone and mineralocorticoid receptor (MR) may play important roles in this process. Therefore, we aim to evaluate the efficacy of MR antagonists on cardiovascular risk factors, including blood pressure (BP), glucose, lipids, renal function, fibrosis and inflammatory and its safety in patients with both hypertension and DM.

METHODS

We searched PubMed, Embase, Web of Science and Cochrane databases for clinical trials published until December 31, 2019. Studies comparing the effect of spironolactone to placebo in patients with hypertension and DM were included. Mean difference with 95% confidence intervals was used to report outcomes.

RESULTS

Eleven randomised placebo-controlled trials with 640 participants were finally included with mean follow-up of 5 months. Compared to placebo, spironolactone significantly reduced office systolic (-6.57, 95%CI: -9.21, -3.93) and diastolic BP (-2.63, 95%CI: -4.25, -1.02) as well as ambulatory BP; increased glycosylated haemoglobin by 0.3 but no clear effect on fasting glucose. Spironolactone induced a significantly reduction of urinary albumin but increased serum creatinine (7.60, 95%CI: 4.94, 10.27) and decreased glomerular filtration rate (-4.28, 95%CI: -6.38, -2.18). Markers of fibrosis and inflammation, including NIIINP, PICP, hs-CRP and TNF-α were also decreased after spironolactone therapy. For lipid metabolism, there was no significant difference between groups. Spironolactone mildly increased serum potassium (0.30, 95%CI: 0.23, 0.37). 2.5% subjects treated with spironolactone experienced mild to moderate hyperkalaemia and received medication or dietary advice and another 1.6% developed severe hyperkalaemia and withdrawn from the studies.

CONCLUSION

Spironolactone reduced BP and urinary albumin, improve fibrosis and inflammation, whereas slightly increases the glycosylated haemoglobin and serum creatinine in patients with hypertension and diabetes. Long-term RCTs to assess the effects of spironolactone on cardiovascular events in this population are warranted.

Development of a New Chemiluminescent Enzyme Immunoassay Using a Two-Step Sandwich Method for Measuring Aldosterone Concentrations

In the present study, we developed a new chemiluminescent enzyme immunoassay (CLEIA) using a two-step sandwich method to measure aldosterone concentrations. We investigated serum and plasma aldosterone concentrations in 75 blood samples from 27 patients using a radioimmunoassay (RIA) and the CLEIA (with current and newly improved reagents) as well as liquid chromatography-tandem mass spectrometry (LC-MS/MS). Based on the results of the Passing–Bablok regression analysis, the aldosterone levels measured using CLEIA with the new reagents and those measured by LC-MS/MS were found to be significantly correlated (slope, 0.984; intercept, 0.2). However, aldosterone levels varied depending on the measurement method (i.e., CLEIA with the new reagent, CLEIA with the current reagent, and RIA). Aldosterone levels were lower with the improved CLEIA method than with RIA and CLEIA using the current reagent. Therefore, the cutoff values of the screening test as well as those of the confirmatory test for primary aldosteronism (PA) should be adjusted to follow current clinical practice guidelines for PA. The formula that can be used to obtain the aldosterone level (pg/mL) when using CLEIA with the new reagent is 0.765 × RIA (pg/mL) − 33.7. This formula will enable PA cutoff values to be set for provisional screening and confirmatory tests.

The importance of the epithelial sodium channel in determining salt sensitivity in people of African origin

Hypertension is highly prevalent in Black Africans and has been found to be associated with worse blood pressure (BP) control and more cardiovascular disease. Black Africans are more salt sensitive with low renin and aldosterone levels. This can be explained in part by variants in the epithelial sodium channel (ENaC) causing an increase in channel activity resulting in sodium and water retention. These variants in the ENaC are increased in the Black African populations presumably due to selective pressure for sodium retention in traditionally low-salt diets. Furthermore, increased endothelial sodium channel activity contributes to the risk of vascular stiffness, which may also result in more difficult to control hypertension. Patients with increased activity of the ENaC are more likely to respond to amiloride (a selective sodium channel antagonist), which has implications for the management of severe and resistant hypertension in Black Africans. A large-scale controlled trial on the use of amiloride compared to usual care is warranted in Blacks with severe or resistant hypertension.

Effect of spironolactone on cardiovascular morbidity and mortality in patients with hypertension and glucose metabolism disorders (ESCAM): a study protocol for a pragmatic randomised controlled trial

INTRODUCTION

Hypertension combined with diabetes and hypokalemia is more likely to develop hyperaldosteronism and is at higher risk of cardiovascular events. There is evidence that activation of aldosterone and mineralocorticoid receptors may play a significant role in the occurrence of cardiovascular events in patients with hypertension and diabetes. Clinical studies have demonstrated that spironolactone can reduce the incidence of cardiovascular events in patients with chronic kidney diseases or severe heart failure. However, the effect of spironolactone on cardiovascular risk in patients with hypertension and glucose metabolism disorders (GMD) and low potassium has been scarcely studied. Therefore, this study aims to evaluate whether add-on spironolactone (conventional antihypertensive drugs alone vs conventional antihypertensive drugs+spironolactone) can reduce the morbidity and mortality of cardiovascular events in this population.

METHODS AND ANALYSIS

In this multicentre, randomised, parallel-controlled study, a total of 7140 hypertensive patients aged 45-75 years with GMD and low potassium will be randomised in a 1:1 manner to the control or the spironolactone group (20 mg/day or with a maximum dose of 40 mg). The primary objective is to estimate the difference in the HR of composite cardiovascular events between the two groups. We will also assess the effects of spironolactone on individual cardiovascular events and the progression of diabetes and renal dysfunction.

ETHICS AND DISSEMINATION

This protocol was approved by the Independent Ethics Committee of People's Hospital of Xinjiang Uygur Autonomous Region (no. 2020020618). The results will be disseminated in peer-reviewed journals and at scientific conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2000028909.

Role of the vascular endothelial sodium channel activation in the genesis of pathologically increased cardiovascular stiffness

Cardiovascular (CV) stiffening represents a complex series of events evolving from pathological changes in individual cells of the vasculature and heart which leads to overt tissue fibrosis. While vascular stiffening occurs naturally with ageing it is accelerated in states of insulin (INS) resistance, such as obesity and type 2 diabetes. CV stiffening is clinically manifested as increased arterial pulse wave velocity and myocardial fibrosis-induced diastolic dysfunction. A key question that remains is how are these events mechanistically linked. In this regard, heightened activation of vascular mineralocorticoid receptors (MR) and hyperinsulinaemia occur in obesity and INS resistance states. Further, a downstream mediator of MR and INS receptor activation, the endothelial cell Na+ channel (EnNaC), has recently been identified as a key molecular determinant of endothelial dysfunction and CV fibrosis and stiffening. Increased activity of the EnNaC results in a number of negative consequences including stiffening of the cortical actin cytoskeleton in endothelial cells, impaired endothelial NO release, increased oxidative stress-meditated NO destruction, increased vascular permeability, and stimulation of an inflammatory environment. Such endothelial alterations impact vascular function and stiffening through regulation of vascular tone and stimulation of tissue remodelling including fibrosis. In the case of the heart, obesity and INS resistance are associated with coronary vascular endothelial stiffening and associated reductions in bioavailable NO leading to heart failure with preserved systolic function (HFpEF). After a brief discussion on mechanisms leading to vascular stiffness per se, this review then focuses on recent findings regarding the role of INS and aldosterone to enhance EnNaC activity and associated CV stiffness in obesity/INS resistance states. Finally, we discuss how coronary artery-mediated EnNaC activation may lead to cardiac fibrosis and HFpEF, a condition that is especially pronounced in obese and diabetic females.

Novel antihypertensive action of rutin is mediated via inhibition of angiotensin converting enzyme/mineralocorticoid receptor/angiotensin 2 type 1 receptor (ATR1) signaling pathways in uninephrectomized hypertensive rats

Hypertension is the most common cardiovascular disease that affects approximately 26% of adult population, worldwide. Rutin is one of the important flavonoids that is consumed in the daily diet, and found in many food items, vegetables, and beverages. Uninephrectomy (UNX) of the left kidney was performed, followed by induction of hypertension. The rats were randomly divided into four groups of 10 rats: group 1-Sham-operated rats; group 2-UNX rats, group 3-UNX-L-NAME (40 mg/kg) plus rutin (100 mg/kg bwt), and groups 4-UNX-L-NAME plus lisinopril (10 mg/kg bwt), orally for 3 weeks. Results revealed significant heightening of arterial pressure and oxidative stress indices, while hypertensive rats treated with rutin had lower expressions of angiotensin converting enzyme (ACE) and mineralocorticoid receptor in uninephrectomized rats. Together, rutin as a novel antihypertensive flavonoid could provide an unimaginable benefits for the management of hypertension through inhibition of angiotensin converting enzyme and mineralocorticoid receptor. PRACTICAL APPLICATIONS: Hypertension has been reported to be the most common cardiovascular disease, affecting approximately 26% of the adult population worldwide with predicted prevalence to increase by 60% by 2025. Recent advances in phytomedicine have shown flavonoids to be very helpful in the treatment of many diseases. Flavonoids have been used in the treatment and management of cardiovascular diseases, obesity and hypertension. The study revealed that rutin, a known flavonoid inhibited angiotensin converting enzyme (ACE), angiotensin 2 type 1 receptor (ATR1), and mineralocorticoid receptor (MCR), comparable to the classic ACE inhibitor, Lisinopril, indicating the novel antihypertensive property of rutin. Therefore, flavonoids such as rutin found in fruits and vegetables could, therefore, serve as an antihypertensive drug regimen. Combining all, functional foods rich in flavonoids could be used as potential therapeutic candidates for managing uninephrectomized hypertensive patients.

[Pharmacological profile, clinical efficacy, and safety of esaxerenone (Minnebro® tablets 1.25 mg, 2.5 mg, 5 mg)]

Esaxerenone is a novel non-steroidal mineralocorticoid receptor antagonisit (MR blocker), whose unique binding to the MR-ligand domain yields a stronger MR antagonistic effect and higher selectivity than existing MR antagonisits. Esaxerenone was approved for the treatment of hypertension in Japan in January 2019. Esaxerenone suppresses the reduction of urinary Na+/K+ ratio in adrenalectomized rats and blood pressure increase, proteinuria, and renal tissue lesions in salt-sensitive hypertensive rats-all in a dose-dependent manner. Esaxerenone is rapidly absorbed and reaches intracellular targets because of its high membrane permeability, exhibits high bioavailability with small interindividual exposure variation, and is metabolized via several pathways (e.g., oxidation, glucuronidation, and hydrolysis), which is associated with low drug-drug interaction risk. As esaxerenone is slightly excreted into urine, its exposure is similar between elderly and non-elderly patients, and between patients with normal and moderately deteriorated renal function. Given its 19-hour half-life, once-daily administration would have a sustainable antihypertensive effect. The ESAX-HTN phase 3 study demonstrated the non-inferiority of esaxerenone's antihypertensive effect versus that of eplerenone in essential hypertension. Another study showed a stable antihypertensive effect for 52 weeks as monotherapy or combination therapy. In hypertensive patients with moderate impairment or both type 2 diabetes and albuminuria treated with a renin-angiotensin system inhibitor, esaxerenone elicited a stable antihypertensive effect and manageable hyperkalemia incidence with titration from a low dose and monitoring including serum potassium. Thus, with careful monitoring of serum potassium, esaxerenone can be administered to patients with moderate renal impairment or both diabetes and albuminuria.

Management of primary aldosteronism and mineralocorticoid receptor-associated hypertension

Resistant hypertension is associated with a poor prognosis due to organ damage caused by prolonged suboptimal blood pressure control. The concomitant use of mineralocorticoid receptor (MR) antagonists with other antihypertensives has been shown to improve blood pressure control in some patients with resistant hypertension, and such patients are considered to have MR-associated hypertension. MR-associated hypertension is classified into two subtypes: one with a high plasma aldosterone level, which includes primary aldosteronism (PA), and the other with a normal aldosterone level. In patients with unilateral PA, adrenalectomy may be the first-choice procedure, while in patients with bilateral PA, MR antagonists are selected. In addition, in patients with other types of MR-associated hypertension with high aldosterone levels, MR antagonists may be selected as a first-line therapy. In patients with normal aldosterone levels, ARBs or ACE inhibitors are used as a first-line therapy, and MR antagonists may be used as an add-on agent. Since MR antagonist therapy may have efficacy as a first-line or add-on agent in these patients, it is important to recognize this type of hypertension. Further studies are needed to elucidate the pathogenesis and management of MR-associated hypertension in more detail to improve the clinical outcomes of patients with MR-associated hypertension.

Antihypertensive power of Naringenin is mediated via attenuation of mineralocorticoid receptor (MCR)/ angiotensin converting enzyme (ACE)/ kidney injury molecule (Kim-1) signaling pathway

Hypertension is a condition with chronic elevation of blood pressure and a common preventable risk factor for cardiovascular disease with attendant global morbidity and mortality. The present study investigated the novel antihypertensive and neuroprotective effect of Naringenin on L-N^G-Nitro arginine methyl ester (L-NAME) induced hypertension together with possible molecular mechanism of action. Rats were divided into four groups. Rats in Group A were normotensive. The hypertensive group (Group B) received 40 mg/kg) of L-NAME alone while Groups C and D were concurrently administered Naringenin (50 mg/kg) or Lisinopril (10 mg/Kg) together with L-NAME orally for 3 weeks. Blood pressure parameters, markers of oxidative stress and renal damage were measured. The immunohistochemistry of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme were also determined. Results indicated significant increases in malondialdehyde, advanced oxidation protein products, protein carbonyl contents and decrease in serum nitric oxide bioavailability in hypertensive rats. Furthermore, there were significant increases in serum myeloperoxidase, urinary creatinine, albumin and blood urea nitrogen in hypertensive rats in comparison to hypertensive rats treated with either Naringenin or Lisinopril. Immunohistochemistry reveal significant expressions of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme in hypertensive rats. However, co-treatment with either Naringenin or Lisinopril mitigated both renal and neuronal oxidative stress, normalized blood pressure and lowered the expressions of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme. Collectively, Naringenin offered a novel antihypertensive and neuroprotective effect through down regulation of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme.

Lysine-Specific Demethylase-1 Deficiency Increases Agonist Signaling Via the Mineralocorticoid Receptor

LSD1 (lysine-specific demethylase-1) is an epigenetic regulator of gene transcription. LSD1 risk allele in humans and LSD1 deficiency (LSD1^+/-) in mice confer increasing salt-sensitivity of blood pressure with age, which evolves into salt-sensitive hypertension in older individuals. However, the mechanism underlying the relationship between LSD1 and salt-sensitivity of blood pressure remains elusive. Here, we show that LSD1 genotype (in humans) and LSD1 deficiency (in mice) lead to similar associations with increased blood pressure and urine potassium levels but with decreased aldosterone levels during a liberal salt diet. Thus, we hypothesized that LSD1 deficiency leads to an MR (mineralocorticoid receptor)-dependent hypertensive state. Yet, further studies in LSD1^+/- mice treated with the MR antagonist eplerenone demonstrate that hypertension, kaliuria, and albuminuria are substantially improved, suggesting that the ligand-independent activation of the MR is the underlying cause of this LSD1 deficiency-mediated phenotype. Indeed, while MR and epithelial sodium channel expression levels were increased in LSD1^+/- mouse kidney tissues, aldosterone secretion from LSD1^+/- glomerulosa cells was significantly lower. Collectively, these data establish that LSD1 deficiency leads to an inappropriate activation and increased levels of the MR during a liberal salt regimen and suggest that inhibiting the MR pathway is a useful strategy for treatment of hypertension in human LSD1 risk allele carriers.