Mineralocorticoid receptor antagonist reduces renal injury in rodent models of types 1 and 2 diabetes mellitus

Finerenone: From the Mechanism of Action to Clinical Use in Kidney Disease

Diabetic kidney disease is a frequent microvascular complication of diabetes and is currently the leading cause of chronic kidney disease and end-stage kidney disease worldwide. Although the prevalence of other complications of diabetes is falling, the number of diabetic patients with end-stage kidney disease in need of kidney replacement therapy is rising. In addition, these patients have extremely high cardiovascular risk. It is more than evident that there is a high unmet treatment need in patients with diabetic kidney disease. Finerenone is a novel nonsteroidal mineralocorticoid receptor antagonist used for treating diabetic kidney disease. It has predominant anti-fibrotic and anti-inflammatory effects and exhibits several renal and cardiac protective effects. This review article summarizes the current knowledge and future prospects of finerenone in treating patients with kidney disease.

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.

Circ_0068087 knockdown attenuates high-glucose-induced human tubular epithelial cell injury in a microribonucleic acid/progestin and adipoQ receptor 3-dependent manner in diabetic nephropathy

AIMS/INTRODUCTION

Previous studies have shown that circular ribonucleic acid mediates the occurrence of diabetic nephropathy. This study aimed to analyze the effects of circ_0068087 on high-glucose (HG)-induced human kidney 2 (HK2) cell dysfunction.

MATERIALS AND METHODS

Circ_0068087, miR-580-3p, and progestin and adipoQ receptor 3 (PAQR3) expression were detected by quantitative reverse transcription polymerase chain reaction. Cell viability and proliferation were investigated by Cell Counting Kit-8 and EdU assays, respectively. The cell apoptotic rate was assessed by flow cytometry. Inflammatory response was assessed by enzyme-linked immunoassays. Oxidative stress was evaluated by a superoxide dismutase activity assay kit and lipid peroxidation malondialdehyde assay kit. Molecular interaction was identified by dual-luciferase reporter assay.

RESULTS

Circ_0068087 and PAQR3 expression were significantly upregulated in diabetic nephropathy patients. HG treatment inhibited HK2 cell proliferation, but induced cell apoptosis, inflammation, oxidative stress and epithelial-mesenchymal transition by regulating circ_0068087. Circ_0068087 acted as a microribonucleic acid-580-3p (miR-580-3p) sponge, and miR-580-3p targeted PAQR3. Furthermore, circ_0068087 depletion repressed PAQR3 expression through miR-580-3p. MiR-580-3p inhibitors or PAQR3 introduction attenuated circ_0068087 silencing mediated-effects in HG-treated HK2 cells.

CONCLUSION

Circ_0068087 promoted HG-induced HK2 cell injuries by the regulation of the miR-580-3p/PAQR3 pathway.

Crosstalk between Aldosterone and Glycation through Rac-1 Induces Diabetic Nephropathy

Background: Advanced glycation end products (AGEs) interaction with its receptor (RAGE) and aldosterone (Aldo) through the mineralocorticoid receptor (MR) activates Rac-1 and NF-κB independently in diabetic nephropathy (DN). However, the crosstalk of Aldo with AGEs-RAGE is still unresolved. Our study examined the impact of the AGEs-Aldo complex on renal cells and its effect on the RAGE-MR interaction. Methods and results: Glycation of human serum albumin (HSA) (40 mg/mL) with methylglyoxal (10 mM) in the presence of Aldo (100 nM) and aminoguanidine (AG) (100 nM) was performed. Glycation markers such as fructosamine and carbonyl groups and fluorescence of AGEs, pentosidine, and tryptophan followed by protein modification were measured. Renal (HEK-293T) cells were treated with the glycated HSA-Aldo (200 μg/mL) along with FPS-ZM1 and spironolactone antagonists for RAGE and Aldo, respectively, for 24 h. Glycation markers and esRAGE levels were measured. Protein and mRNA levels of RAGE, MR, Rac-1, and NF-κB were estimated. Glycation markers were enhanced with Aldo when albumin was only 14-16% glycated. AGEs-Aldo complex upregulated RAGE, MR, Rac-1 and NF-κB expressions. However, FPS-ZM1 action might have activated the RAGE-independent pathway, further elevating MR, Rac-1, and NF-κB levels. Conclusion: Our study concluded that the presence of Aldo has a significant impact on glycation. In the presence of AGEs-Aldo, RAGE-MR crosstalk exerts inflammatory responses through Rac-1 in DN. Insights into this molecular interplay are crucial for developing novel therapeutic strategies to alleviate DN in the future.

Blockade of the mineralocorticoid receptor improves markers of human endothelial cell dysfunction and hematological indices in a mouse model of sickle cell disease

Increased endothelin-1 (ET-1) levels in patients with sickle cell disease (SCD) and transgenic mouse models of SCD contribute to disordered hematological, vascular, and inflammatory responses. Mineralocorticoid receptor (MR) activation by aldosterone, a critical component of the Renin-Angiotensin-Aldosterone-System, modulates inflammation and vascular reactivity, partly through increased ET-1 expression. However, the role of MR in SCD remains unclear. We hypothesized that MR blockade in transgenic SCD mice would reduce ET-1 levels, improve hematological parameters, and reduce inflammation. Berkeley SCD (BERK) mice, a model of severe SCD, were randomized to either sickle standard chow or chow containing the MR antagonist (MRA), eplerenone (156 mg/Kg), for 14 days. We found that MRA treatment reduced ET-1 plasma levels (p = .04), improved red cell density gradient profile (D₅₀ ; p < .002), and increased mean corpuscular volume in both erythrocytes (p < .02) and reticulocytes (p < .024). MRA treatment also reduced the activity of the erythroid intermediate-conductance Ca²⁺ -activated K⁺ channel - K_Ca 3.1 (Gardos channel, KCNN4), reduced cardiac levels of mRNAs encoding ET-1, Tumor Necrosis Factor Receptor-1, and protein disulfide isomerase (PDI) (p < .01), and decreased plasma PDI and myeloperoxidase activity. Aldosterone (10^-8  M for 24 h in vitro) also increased PDI mRNA levels (p < .01) and activity (p < .003) in EA.hy926 human endothelial cells, in a manner blocked by pre-incubation with the MRA canrenoic acid (1 μM; p < .001). Our results suggest a novel role for MR activation in SCD that may exacerbate SCD pathophysiology and clinical complications.

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.

Benefits of the Non-Steroidal Mineralocorticoid Receptor Antagonist Finerenone in Metabolic Syndrome-Related Heart Failure with Preserved Ejection Fraction

The mineralocorticoid receptor (MR) plays an important role in the development of chronic kidney disease (CKD) and associated cardiovascular complications. Antagonizing the overactivation of the MR with MR antagonists (MRA) is a therapeutic option, but their use in patients with CKD is limited due to the associated risk of hyperkalemia. Finerenone is a non-steroidal MRA associated with an improved benefit-risk profile in comparison to steroidal MRAs. In this study, we decided to test whether finerenone improves renal and cardiac function in male hypertensive and diabetic ZSF1 rats as an established preclinical HFpEF model. Finerenone was administered at 10 mg/kg/day for 12 weeks. Cardiac function/hemodynamics were assessed in vivo. ZSF1 rats showed classical signs of CKD with increased BUN, UACR, hypertrophy, and fibrosis of the kidney together with characteristic signs of HFpEF including cardiac fibrosis, diastolic dysfunction, and decreased cardiac perfusion. Finerenone treatment did not impact kidney function but reduced renal hypertrophy and cardiac fibrosis. Interestingly, finerenone ameliorated diastolic dysfunction and cardiac perfusion in ZSF1 rats. In summary, we show for the first time that non-steroidal MR antagonism by finerenone attenuates cardiac diastolic dysfunction and improves cardiac perfusion in a preclinical HFpEF model. These cardiac benefits were found to be largely independent of renal benefits.

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.

Beyond Blood Glucose and Blood Pressure Control in Type 2 Diabetes: Alternative Management Strategies to Prevent the Development and Progression of CKD

Chronic kidney disease associated with Type 2 diabetes is linked to significant increase in morbidity, reduced quality of life, and early death. Current guidelines recommend targets for the management of hyperglycemia, hypertension, and dyslipidemia but there remains a residual risk of chronic kidney disease progression and adverse cardiovascular outcomes in patients with Type 2 diabetes. The 2022 consensus report from the American Diabetes Association and Kidney Disease: Improving Global Outcomes support the use of sodium-glucose co-transporter 2 inhibitors and nonsteroidal mineralocorticoid receptor antagonists to improve kidney and cardiovascular outcomes. Coordination between those working in the primary care setting and those in endocrinology and nephrology clinics may optimize the prevention of chronic kidney disease progression in patients with Type 2 diabetes. Nurse practitioners, physician assistants, and primary care physicians play an important role in making timely patient referrals to kidney specialists. This article explores the use of novel therapies capable of reducing the risk of cardiovascular disease and chronic kidney disease progression beyond what can be achieved with control of blood glucose, blood pressure, and lipid levels. It also discusses the importance of monitoring at-risk patients to facilitate early diagnosis and initiation of effective kidney-protective therapy.[Media: see text][Figure: see text].

Advances in the management of diabetic kidney disease: beyond sodium-glucose co-transporter 2 inhibitors

Progress in the treatment of diabetic kidney disease (DKD) has been modest since the early trials on renin-angiotensin-aldosterone system inhibitors (RAASis). Although sodium-glucose co-transporter 2 inhibitors (SGLT2is) have revolutionized the management of DKD by lowering proteinuria and protecting organs, other novel treatment approaches with good evidence and efficacy that can be used in conjunction with a RAASi or SGLT2i in managing DKD have emerged in the past few years. This review discusses the evidence for glucagon-like peptide-1 receptor agonist, selective mineralocorticoid receptor antagonist, and selective endothelin A receptor antagonist, emerging treatment options for DKD beyond SGLT2 inhibition.

Recent Advances in the Emerging Therapeutic Strategies for Diabetic Kidney Diseases

Diabetic kidney disease (DKD) is one of the most common causes of end-stage renal disease worldwide. The treatment of DKD is strongly associated with clinical outcomes in patients with diabetes mellitus. Traditional therapeutic strategies focus on the control of major risk factors, such as blood glucose, blood lipids, and blood pressure. Renin–angiotensin–aldosterone system inhibitors have been the main therapeutic measures in the past, but the emergence of sodium–glucose cotransporter 2 inhibitors, incretin mimetics, and endothelin-1 receptor antagonists has provided more options for the management of DKD. Simultaneously, with advances in research on the pathogenesis of DKD, some new therapies targeting renal inflammation, fibrosis, and oxidative stress have gradually entered clinical application. In addition, some recently discovered therapeutic targets and signaling pathways, mainly in preclinical and early clinical trial stages, are expected to provide benefits for patients with DKD in the future. This review summarizes the traditional treatments and emerging management options for DKD, demonstrating recent advances in the therapeutic strategies for DKD.

Modifying chronic kidney disease progression with the mineralocorticoid receptor antagonist finerenone in patients with type 2 diabetes

In patients with type 2 diabetes, chronic kidney disease (CKD) is the most common cause of kidney failure. With its increasing prevalence and limited treatment options, CKD is a major contributor to the global burden of disease. Although recent guidelines for the control of hypertension and hyperglycaemia, as well as the use of renin-angiotensin system inhibitors and, more recently, sodium-glucose co-transporter-2 inhibitors, have improved outcomes for patients with CKD and diabetes, there is still a high residual risk of CKD progression and adverse cardiovascular events. In this review, we discuss the recently published FIDELIO-DKD and FIGARO-DKD studies and FIDELITY prespecified individual patient analysis. Together, these studies have established finerenone, a novel non-steroidal mineralocorticoid receptor antagonist, as an effective treatment for kidney and cardiovascular protection and welcome addition to the pillars of treatment to slow CKD progression in patients with type 2 diabetes.

Increased glucocorticoid metabolism in diabetic kidney disease

Aims

Glomerular damage indicated by proteinuria is a main symptom in diabetic nephropathy. Mineralocorticoid receptor (MR) antagonists (MRAs) are beneficial irrespective of aldosterone availability. Thus, we hypothesized an alternatively activated MR to promote glomerular damage in proteinuric diabetic nephropathy. Specifically, we aimed first to demonstrate the presence of steroid hormones serving as alternative MR targets in type II diabetic patients with proteinuric kidney disease, second whether MR selectivity was modified, third to characterize MR and glucocorticoid receptor (GR) expression and activity in glomerular cell types exposed to eu- and hyperglycemic conditions, fourth to characterize the pro-fibrotic potential of primary human renal mesangial cells (HRMC) upon stimulation with aldosterone and cortisol, and fifth to specify the involvement of the MR and/or GR in pro-fibrotic signaling.

Materials and methods

Urinary steroid hormone profiles of patients with diabetic kidney disease were analyzed by gas chromatography–mass spectrometry and compared to an age and gender matched healthy control group taken out of a population study. In both cohorts, the activity of the MR pre-receptor enzyme 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2), which inactivates cortisol to prevent it from binding to the MR, was assessed to define a change in MR selectivity. Expression of HSD11B2, MR and GR was quantified in HRMC and primary human renal glomerular endothelial cells (HRGEC). Activity of MR and GR was explored in HRMC by measuring the MR/GR down-stream signal SGK1 and the pro-fibrotic genes TGFB1, FN1 and COL1A1 in normal and high glucose conditions with the MR/GR agonists aldosterone/cortisol and the MR/GR antagonists spironolactone/RU486.

Results

Patients with diabetic kidney disease excreted more tetrahydroaldosterone than the control group reaching significance in men. The excretion of MR-agonistic steroid hormones was only increased for 18-hydroxytetrahydrocorticosterone in diabetic women. The excretion of most glucocorticoids was higher in the diabetic cohort. Higher apparent systemic HSD11B2 activity suggested less activation of the MR by cortisol in diabetic patients. Both cell types, HRMC and HRGEC, lacked expression of HSD11B2. Hyperglycemic conditions did not change MR and GR expression and activity. Stimulation with both aldosterone and cortisol promoted upregulation of pro-fibrotic genes in HRMC. This effect of MR and/or GR activation was more pronounced in high glucose conditions and partially inhibited by MRAs and GR antagonists.

Conclusions

In patients with diabetic kidney disease alternative MR activation is conceivable as cortisol and cortisone metabolites are increased. Systemic availability of active metabolites is counteracted via an increased HSD11B2 activity. As this cortisol deactivation is absent in HRMC and HRGEC, cortisol binding to the MR is enabled. Both, cortisol and aldosterone stimulation led to an increased expression of pro-fibrotic genes in HRMC. This mechanism was related to the MR as well as the GR and more marked in high glucose conditions linking the benefit of MRAs in diabetic kidney disease to these findings.

A Selective Mineralocorticoid Receptor Blocker, Esaxerenone, Attenuates Vascular Dysfunction in Diabetic C57BL/6 Mice

AIMS

Pharmacological blockade of mineralocorticoid receptors (MRs) is a potential therapeutic approach to reduce cardiovascular complications since MRs play a crucial role in cardiovascular regulation. Recent studies suggest that MR antagonists affect several extrarenal tissues, including vessel function. We investigated the effect of a novel nonsteroidal selective MR blocker, esaxerenone, on diabetes-induced vascular dysfunction.

METHODS

Diabetes was induced by a single dose of streptozotocin in 8-week-old male C57BL/6 mice. Esaxerenone (3 mg/kg/day) or a vehicle was administered by gavage to diabetic mice for 3 weeks. Metabolic parameters, plasma aldosterone levels, and parameters related to renal function were measured. Endothelium-dependent or -independent vascular responses of the aortic segments were analyzed with acetylcholine or sodium nitroprusside, respectively. Human umbilical vein endothelial cells (HUVECs) were used for the in vitro study.

RESULTS

Induction of diabetes elevated plasma aldosterone level (P＜0.05) and impaired endothelium-dependent vascular relaxation (P＜0.05). The administration of esaxerenone ameliorated the endothelial dysfunction (P＜0.01) without the alteration of metabolic parameters, blood pressure, and renal function. Esaxerenone improved the eNOS^Ser1177 phosphorylation in the aorta obtained from diabetic mice (P＜0.05) compared with that in the vehicle-treated group. Furthermore, a major MR agonist, aldosterone, decreased eNOS^Ser1177 phosphorylation and increased eNOS^Thr495 phosphorylation in HUVECs, which recovered with esaxerenone. Esaxerenone ameliorated the endothelium-dependent vascular relaxation caused by aldosterone in the aortic segments obtained from C57BL/6 mice (P＜0.001).

CONCLUSION

Esaxerenone attenuates the development of diabetes-induced endothelial dysfunction in mice. These results suggest that esaxerenone has potential vascular protective effects in individuals with diabetes.

Efficacy and Safety of Novel Non-steroidal Mineralocorticoid Receptor Antagonist Finerenone in the Management of Diabetic Kidney Disease: A Meta-analysis

BACKGROUND

Data are scant on use of finerenone in diabetic kidney disease (DKD). We undertook this meta-analysis to address this knowledge gap.

METHODS

Electronic databases were searched for randomized controlled trials (RCTs) involving diabetes patients receiving finerenone compared to controls. The primary outcome was changes in urine albumin-creatinine ratio (UACR). Secondary outcomes were time to kidney failure (decline in GFR by >40% from baseline over 4 weeks), time to end-stage kidney disease, hospitalization for any cause, death and adverse events reported.

RESULTS

From initially screened 79 articles, data from 7 RCTs involving 13,783 patients were analyzed (3 in active control group [ACG] defined as having eplerenone/spironolactone as active comparator; 4 in passive control group [PCG] defined as having placebo as controls). Patients receiving finerenone had greater percentage lowering of UACR from baseline as compared to PCG [MD23.82% (95%CI: -24.87 to -22.77); P < 0.01; I ² = 96%] at 90 days, after 2 years [MD 37.9% (95%CI: -38.09 to -37.71); P < 0.01] and 4 years [MD 25.20%(95%CI: -25.63 to -24.77);P < 0.01] of treatment. Patients receiving finerenone has lower chance of >40% decline in GFR (OR 0.83 [95%CI: 0.75 to 0.92];P < 0.01; I ² = 0%). Patients receiving finerenone had lower occurrence of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke or hospitalization for heart failure, as compared to placebo/eplerenone (OR0.86 [95%CI: 0.78 to 0.95]; P = 0.003; I ² = 0%). TAEs was similar (RR0.97 [95%CI: 0.88-1.07]; P = 0.56; I ² = 0%), but SAEs significantly lower (RR0.91 [95%CI: 0.84 to 0.97]; P < 0.01; I ² = 0%) in finerenone-group compared to controls.

CONCLUSION

This meta-analysis provides reassuring data on beneficial impact of finerenone in reducing UACR and GFR decline as compared to placebo. We still lack head-to-head comparison of renal outcomes of finerenone vs eplerenone/spironolactone in DKD.

MicroRNAs and their delivery in diabetic fibrosis

The global prevalence of diabetes mellitus was estimated to be 463 million people in 2019 and is predicted to rise to 700 million by 2045. The associated financial and societal costs of this burgeoning epidemic demand an understanding of the pathology of this disease, and its complications, that will inform treatment to enable improved patient outcomes. Nearly two decades after the sequencing of the human genome, the significance of noncoding RNA expression is still being assessed. The family of functional noncoding RNAs known as microRNAs regulates the expression of most genes encoded by the human genome. Altered microRNA expression profiles have been observed both in diabetes and in diabetic complications. These transcripts therefore have significant potential and novelty as targets for therapy, therapeutic agents and biomarkers.

Prediction of the endocrine-disrupting ability of 49 per- and polyfluoroalkyl substances: In silico and epidemiological evidence

The toxic effects of per- and polyfluoroalkyl substances (PFASs) on humans are mediated by nuclear hormone receptors (NHRs). However, data on the interaction of PFASs and NHRs is limited. Endocrine Disruptome, an inverse docking tool, was used in this study to simulate the docking of 49 common PFASs with 14 different types of human NHRs. According to the findings, 25 PFASs have a high or moderately high probability of binding to more than five NHRs, with androgen receptor (AR) and mineralocorticoid receptor (MR) being the most likely target NHRs. Molecular docking analyses revealed that the binding modes of PFASs with the two NHRs were similar to those of their corresponding co-crystallized ligands. PFASs, in particular, may disrupt the endocrine system by binding to MR. This finding is consistent with epidemiological research that has linked PFASs to MR-related diseases. Our findings may contribute to a better understanding of the health risks posed by PFASs.

Efficacy and safety of finerenone in patients with chronic kidney disease and type 2 diabetes by GLP-1RA treatment: A subgroup analysis from the FIDELIO-DKD trial

AIMS

Finerenone significantly reduced the risk of kidney and cardiovascular (CV) outcomes in patients with chronic kidney disease and type 2 diabetes in the FIDELIO-DKD trial (NCT02540993). This exploratory subgroup analysis investigates the effect of glucagon-like peptide-1 receptor agonist (GLP-1RA) use on the treatment effect of finerenone.

MATERIALS AND METHODS

Patients with type 2 diabetes, urine albumin-to-creatinine ratio (UACR) 30-5000 mg/g and estimated glomerular filtration rate 25-<75 ml/min per 1.73 m² receiving optimized renin-angiotensin system blockade were randomized to finerenone or placebo.

RESULTS

Of the 5674 patients analysed, overall, 394 (6.9%) received GLP-1RAs at baseline. A reduction in UACR with finerenone was observed with or without baseline GLP-1RA use; ratio of least-squares means 0.63 (95% confidence interval 0.56, 0.70) with GLP-1RA use and 0.69 (95% confidence interval 0.67, 0.72) without GLP-1RA use (p value for interaction .20). Finerenone also significantly reduced the primary kidney (time to kidney failure, sustained decrease in estimated glomerular filtration rate ≥40% from baseline, or renal death) and key secondary CV outcomes (time to CV death, non-fatal myocardial infarction, non-fatal stroke, or hospitalization for heart failure) versus placebo, with no clear difference because of GLP-1RA use at baseline (p value for interaction .15 and .51 respectively) or any time during the trial. The safety profile of finerenone was similar between subgroups.

CONCLUSIONS

This exploratory subgroup analysis suggests that finerenone reduces UACR in patients with or without GLP-1RA use at baseline, and the effects on kidney and CV outcomes are consistent irrespective of GLP-1RA use.

Mineralocorticoid receptor antagonists in diabetic kidney disease - mechanistic and therapeutic effects

Chronic kidney disease (CKD) is the leading complication in type 2 diabetes (T2D) and current therapies that limit CKD progression and the development of cardiovascular disease (CVD) include angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers and sodium-glucose co-transporter 2 (SGLT2) inhibitors. Despite the introduction of these therapeutics, an important residual risk of CKD progression and cardiovascular death remains in patients with T2D. Mineralocorticoid receptor antagonists (MRAs) are a promising therapeutic option in diabetic kidney disease (DKD) owing to the reported effects of mineralocorticoid receptor activation in inflammatory cells, podocytes, fibroblasts, mesangial cells and vascular cells. In preclinical studies, MRAs consistently reduce albuminuria, CKD progression, and activation of fibrotic and inflammatory pathways. DKD clinical studies have similarly demonstrated that steroidal MRAs lead to albuminuria reduction compared with placebo, although hyperkalaemia is a major secondary effect. Non-steroidal MRAs carry a lower risk of hyperkalaemia than steroidal MRAs, and the large FIDELIO-DKD clinical trial showed that the non-steroidal MRA finerenone also slowed CKD progression and reduced the risk of adverse cardiovascular outcomes compared with placebo in patients with T2D. Encouragingly, other non-steroidal MRAs have anti-albuminuric properties in DKD. Whether or not combining MRAs with other renoprotective drugs such as SGLT2 inhibitors might provide additive protective effects warrants further investigation.

The mineralocorticoid receptor in chronic kidney disease

Chronic kidney disease (CKD) is a major public health concern, affecting approximately 10% of the population worldwide. CKD of glomerular or tubular origin leads to the activation of stress mechanisms, including the renin angiotensin aldosterone system and mineralocorticoid receptor (MR) activation. Over the last two decades, blockade of the MR has arisen as a potential therapeutic approach against various forms of kidney disease. In this review, we summarize the experimental studies that have shown a protective effect of MR antagonists (MRAs) in non-diabetic and diabetic CKD animal models. Moreover, we review the main clinical trials that have shown the clinical application of MRAs to reduce albuminuria and, importantly, to slow CKD progression. Recent evidence from the FIDELIO trial showed that the MRA finerenone can reduce hard kidney outcomes when added to the standard of care in CKD associated with type 2 diabetes. Finally, we discuss the effects of MRAs relative to those of SGLT2 inhibitors, as well as the potential benefit of combination therapy to maximize organ protection.

Mineralocorticoid Receptor Antagonists in Diabetic Kidney Disease

Diabetes mellitus is a global health issue and main cause of chronic kidney disease. Both diseases are also linked through high cardiovascular morbidity and mortality. Diabetic kidney disease (DKD) is present in up to 40% of diabetic patients; therefore, prevention and treatment of DKD are of utmost importance. Much research has been dedicated to the optimization of DKD treatment. In the last few years, mineralocorticoid receptor antagonists (MRA) have experienced a renaissance in this field with the development of non-steroidal MRA. Steroidal MRA have known cardiorenal benefits, but their use is limited by side effects, especially hyperkalemia. Non-steroidal MRA still block the damaging effects of mineralocorticoid receptor overactivation (extracellular fluid volume expansion, inflammation, fibrosis), but with fewer side effects (hormonal, hyperkalemia) than steroidal MRA. This review article summarizes the current knowledge and newer research conducted on MRA in DKD.

Activation of Rac1-Mineralocorticoid Receptor Pathway Contributes to Renal Injury in Salt-Loaded db/db Mice

[Figure: see text].

Nonsteroidal Mineralocorticoid Receptor Antagonists: Exploring Role in Cardiovascular Disease

ABSTRACT

Aldosterone, a mineralocorticoid hormone, plays a role in the pathophysiology of many cardiovascular disease states. Mineralocorticoid receptor antagonists (MRAs) have been shown to improve clinical outcomes in select patient populations. However, use of available steroidal receptor antagonists, eplerenone and spironolactone, is often limited by the risk or development of hyperkalemia. Nonsteroidal MRAs have been designed to overcome this limitation. The nonsteroidal MRAs have been studied in patients with heart failure with reduced ejection fraction, hypertension, and to lower the risk of cardiac and renal outcomes in those with type 2 diabetes and renal disease. In this review, the pharmacology of the MRAs is compared, the data evaluating the use of nonsteroidal MRAs are examined, and the place of this new generation of therapy is discussed. At this time, it seems that there could be a future role for nonsteroidal MRAs to reduce the risk of renal outcomes in high-risk individuals.

The safety and efficacy of low-dose mineralocorticoid receptor antagonists in dialysis patients: A meta-analysis

INTRODUCTION

Our aim was to evaluate the safety and efficacy of low-dose mineralocorticoid receptor antagonists (MRAs) in dialysis patients.

METHODS

We systematically searched PubMed, EMBASE, and Cochrane libraries for clinical trials on the use of MRAs in dialysis patients. Review Manager 5.3 software was used to analyze relevant data and evaluate the quality of evidence.

RESULTS

We identified nine randomized controlled trials including 1128 chronic dialysis patients. In terms of safety, when hyperkalemia was defined as serum potassium level ≥5.5 mmol/L, low-dose MRAs were significantly associated with hyperkalemia (relative risk [RR] 1.76, 95% confidence intervals [CI] 1.07-2.89, P = .02); however, when hyperkalemia was defined as serum potassium level ≥6.0 mmol/L or serum potassium level ≥6.5 mmol/L, no significant association was observed between low-dose MRAs and hyperkalemia (RR 1.40, 95% CI 0.83-2.37, P = .20; RR 1.98, 95% CI 0.91-4.30, P = .09, respectively). Use of low-dose MRAs can reduce cardiovascular mortality by 54% compared with the control group (0.46, 95% CI 0.28-0.76, P = .003). Similarly, the RR of all-cause mortality for the low-dose MRAs group was 0.48 (95% CI 0.33-0.72, P = .0003).

CONCLUSION

Low-dose MRAs may benefit dialysis patients without significantly increasing moderate to severe hyperkalemia.

Effect of Finerenone on Chronic Kidney Disease Outcomes in Type 2 Diabetes

BACKGROUND

Finerenone, a nonsteroidal, selective mineralocorticoid receptor antagonist, reduced albuminuria in short-term trials involving patients with chronic kidney disease (CKD) and type 2 diabetes. However, its long-term effects on kidney and cardiovascular outcomes are unknown.

METHODS

In this double-blind trial, we randomly assigned 5734 patients with CKD and type 2 diabetes in a 1:1 ratio to receive finerenone or placebo. Eligible patients had a urinary albumin-to-creatinine ratio (with albumin measured in milligrams and creatinine measured in grams) of 30 to less than 300, an estimated glomerular filtration rate (eGFR) of 25 to less than 60 ml per minute per 1.73 m² of body-surface area, and diabetic retinopathy, or they had a urinary albumin-to-creatinine ratio of 300 to 5000 and an eGFR of 25 to less than 75 ml per minute per 1.73 m². All the patients were treated with renin-angiotensin system blockade that had been adjusted before randomization to the maximum dose on the manufacturer's label that did not cause unacceptable side effects. The primary composite outcome, assessed in a time-to-event analysis, was kidney failure, a sustained decrease of at least 40% in the eGFR from baseline, or death from renal causes. The key secondary composite outcome, also assessed in a time-to-event analysis, was death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure.

RESULTS

During a median follow-up of 2.6 years, a primary outcome event occurred in 504 of 2833 patients (17.8%) in the finerenone group and 600 of 2841 patients (21.1%) in the placebo group (hazard ratio, 0.82; 95% confidence interval [CI], 0.73 to 0.93; P = 0.001). A key secondary outcome event occurred in 367 patients (13.0%) and 420 patients (14.8%) in the respective groups (hazard ratio, 0.86; 95% CI, 0.75 to 0.99; P = 0.03). Overall, the frequency of adverse events was similar in the two groups. The incidence of hyperkalemia-related discontinuation of the trial regimen was higher with finerenone than with placebo (2.3% and 0.9%, respectively).

CONCLUSIONS

In patients with CKD and type 2 diabetes, treatment with finerenone resulted in lower risks of CKD progression and cardiovascular events than placebo. (Funded by Bayer; FIDELIO-DKD ClinicalTrials.gov number, NCT02540993.).

Role of mineralocorticoid receptor antagonists in kidney diseases

Mineralocorticoid receptor (MR) antagonists, for example, spironolactone and eplerenone, are in clinical use to treat hypertension. Increasing evidence suggests that mineralocorticoid receptor activation causes the pathogenesis and progression of chronic kidney disease. Aldosterone-induced MR activation increases inflammation, fibrosis, and oxidative stress in the kidney. MR antagonists (MRAs) have demonstrated therapeutic actions in chronic kidney disease (CKD), diabetic nephropathy (DN), renal fibrosis, and drug-induced renal injury in preclinical and clinical studies. We have summarized and discussed these studies in this review. The nonsteroidal MRA, esaxerenone, recently received approval for the treatment of hypertension. It has also shown a positive therapeutic effect in phase 3 clinical trials in patients with DN. Other nonsteroidal MRA such as apararenone, finerenone, AZD9977, and LY2623091 are in different clinical trials in patients with hypertension suffering from renal or hepatic fibrotic diseases. Hyperkalemia associated with MRA therapy has frequently led to the discontinuation of the treatment. The new generation nonsteroidal MRAs like esaxerenone are less likely to cause hyperkalemia at therapeutic doses. It appears that the nonsteroidal MRAs can provide optimum therapeutic benefit for patients suffering from kidney diseases.

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.

Striatin heterozygous mice are more sensitive to aldosterone-induced injury

Aldosterone modulates the activity of both epithelial (specifically renal) and non-epithelial cells. Binding to the mineralocorticoid receptor (MR), activates two pathways: the classical genomic and the rapidly activated non-genomic that is substantially modulated by the level of striatin. We hypothesized that disruption of MR's non-genomic pathway would alter aldosterone-induced cardiovascular/renal damage. To test this hypothesis, wild type (WT) and striatin heterozygous knockout (Strn+/-) littermate male mice were fed a liberal sodium (1.6% Na+) diet and randomized to either protocol one: 3 weeks of treatment with either vehicle or aldosterone plus/minus MR antagonists, eplerenone or esaxerenone or protocol two: 2 weeks of treatment with either vehicle or L-NAME/AngII plus/minus MR antagonists, spironolactone or esaxerenone. Compared to the WT mice, basally, the Strn+/- mice had greater (~26%) estimated renal glomeruli volume and reduced non-genomic second messenger signaling (pAkt/Akt ratio) in kidney tissue. In response to active treatment, the striatin-associated-cardiovascular/renal damage was limited to volume effects induced by aldosterone infusion: significantly increased blood pressure (BP) and albuminuria. In contrast, with aldosterone or L-NAME/AngII treatment, striatin deficiency did not modify aldosterone-mediated damage: in the heart and kidney, macrophage infiltration, and increases in aldosterone-induced biomarkers of injury. All changes were near-normalized following MR blockade with spironolactone or esaxerenone, except increased BP in the L-NAME/AngII model. In conclusion, the loss of striatin amplified aldosterone-induced damage suggesting that aldosterone's non-genomic pathway is protective but only related to effects likely mediated via epithelial, but not non-epithelial cells.

Aldosterone and the mineralocorticoid receptor in renal injury: A potential therapeutic target in feline chronic kidney disease

There is a growing body of experimental and clinical evidence supporting mineralocorticoid receptor (MR) activation as a powerful mediator of renal damage in laboratory animals and humans. Multiple pathophysiological mechanisms are proposed, with the strongest evidence supporting aldosterone-induced vasculopathy, exacerbation of oxidative stress and inflammation, and increased growth factor signalling promoting fibroblast proliferation and deranged extracellular matrix homeostasis. Further involvement of the MR is supported by extensive animal model experiments where MR antagonists (such as spironolactone and eplerenone) abrogate renal injury, including ischaemia-induced damage. Additionally, clinical trials have shown MR antagonists to be beneficial in human chronic kidney disease (CKD) in terms of reducing proteinuria and cardiovascular events, though current studies have not evaluated primary end points which allow conclusions to made about whether MR antagonists reduce mortality or slow CKD progression. Although differences between human and feline CKD exist, feline CKD shares many characteristics with human disease including tubulointerstitial fibrosis. This review evaluates the evidence for the role of the MR in renal injury and summarizes the literature concerning aldosterone in feline CKD. MR antagonists may represent a promising therapeutic strategy in feline CKD.

Pathophysiologic mechanisms in diabetic kidney disease: A focus on current and future therapeutic targets

Diabetic kidney disease (DKD) is the primary cause of chronic kidney disease around the globe and is one of the main complications in patients with type 1 and 2 diabetes. The standard treatment for DKD is drugs controlling hyperglycemia and high blood pressure. Renin angiotensin aldosterone system blockade and sodium glucose cotransporter 2 (SGLT2) inhibition have yielded promising results in DKD, but many diabetic patients on such treatments nevertheless continue to develop DKD, leading to kidney failure and cardiovascular comorbidities. New therapeutic options are urgently required. We review here the promising therapeutic avenues based on insights into the mechanisms of DKD that have recently emerged, including mineralocorticoid receptor antagonists, SGLT2 inhibitors, glucagon-like peptide-1 receptor agonist, endothelin receptor A inhibition, anti-inflammatory agents, autophagy activators and epigenetic remodelling. The involvement of several molecular mechanisms in DKD pathogenesis, together with the genetic and epigenetic variability of this condition, makes it difficult to target this heterogeneous patient population with a single drug. Personalized medicine, taking into account the genetic and mechanistic variability, may therefore improve renal and cardiovascular protection in diabetic patients with DKD.

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.

Vascular and inflammatory mineralocorticoid receptors in kidney disease

Mineralocorticoid receptor (MR) activation in the kidney can occur outside the aldosterone-sensitive distal nephron in sites including the endothelium, smooth muscle and inflammatory cells. MR activation in these cells has deleterious effects on kidney structure and function by promoting oxidative injury, endothelial dysfunction and stiffness, vascular remodelling and calcification, decreased relaxation and activation of T cells and pro-inflammatory macrophages. Here, we review the data showing the cellular consequences of MR activation in endothelial, smooth muscle and inflammatory cells and how this affects the kidney in pathological situations. The evidence demonstrating a benefit of pharmacological or genetic MR inhibition in various models of kidney disease is also discussed.

NLRP3 Inflammasome and Mineralocorticoid Receptors Are Associated with Vascular Dysfunction in Type 2 Diabetes Mellitus

Aldosterone excess aggravates endothelial dysfunction in diabetes and hypertension by promoting the increased generation of reactive oxygen species, inflammation, and insulin resistance. Aldosterone activates the molecular platform inflammasome in immune system cells and contributes to vascular dysfunction induced by the mineralocorticoid hormone. It is unclear as to whether the NLRP3 inflammasome associated with the mineralocorticoid receptor contributes to vascular dysfunction in diabetic conditions. Here, we tested the hypothesis that an excess of aldosterone induces vascular dysfunction in type 2 diabetes, via the activation of mineralocorticoid receptors (MR) and assembly of the NLRP3 inflammasome. Mesenteric resistance arteries from control (db/m) and diabetic (db/db) mice treated with vehicle, spironolactone (MR antagonist) or an NLRP3 selective inhibitor (MCC950) were used to determine whether NLRP3 contributes to diabetes-associated vascular dysfunction. Db/db mice exhibited increased vascular expression/activation of caspase-1 and IL-1β, increased plasma IL-1β levels, active caspase-1 in peritoneal macrophages, and reduced acetylcholine (ACh) vasodilation, compared to db/m mice. Treatment of db/db mice with spironolactone and MCC950 decreased plasma IL-1β and partly restored ACh vasodilation. Spironolactone also reduced active caspase-1-positive macrophages in db/db mice, events that contribute to diabetes-associated vascular changes. These data clearly indicate that MR and NLRP3 activation contribute to diabetes-associated vascular dysfunction and pro-inflammatory phenotype.

Sex-specific differences in endoplasmic reticulum aminopeptidase 1 modulation influence blood pressure and renin-angiotensin system responses

Salt sensitivity of blood pressure (SSBP) and hypertension are common, but the underlying mechanisms remain unclear. Endoplasmic reticulum aminopeptidase 1 (ERAP1) degrades angiotensin II (ANGII). We hypothesized that decreasing ERAP1 increases BP via ANGII-mediated effects on aldosterone (ALDO) production and/or renovascular function. Compared with WT littermate mice, ERAP1-deficient (ERAP1+/-) mice had increased tissue ANGII, systolic and diastolic BP, and SSBP, indicating that ERAP1 deficiency leads to volume expansion. However, the mechanisms underlying the volume expansion differed according to sex. Male ERAP1+/- mice had increased ALDO levels and normal renovascular responses to volume expansion (decreased resistive and pulsatility indices and increased glomerular volume). In contrast, female ERAP1+/- mice had normal ALDO levels but lacked normal renovascular responses. In humans, ERAP1 rs30187, a loss-of-function gene variant that reduces ANGII degradation in vitro, is associated with hypertension. In our cohort from the Hypertensive Pathotype (HyperPATH) Consortium, there was a significant dose-response association between rs30187 risk alleles and systolic and diastolic BP as well as renal plasma flow in men, but not in women. Thus, lowering ERAP1 led to volume expansion and increased BP. In males, the volume expansion was due to elevated ALDO with normal renovascular function, whereas in females the volume expansion was due to impaired renovascular function with normal ALDO levels.

Design and Baseline Characteristics of the Finerenone in Reducing Kidney Failure and Disease Progression in Diabetic Kidney Disease Trial

BACKGROUND

Among diabetics, those with kidney disease have exceptionally high rates of cardiovascular (CV) morbidity and mortality, and progression of their underlying disease. Finerenone is a novel, non-steroidal, selective mineralocorticoid-receptor antagonist which has shown to reduce albuminuria in type 2 diabetes (T2D) patients with chronic kidney disease (CKD), while revealing only a low risk of hyperkalemia. However, the effect of finerenone on renal and CV outcomes has not been investigated in long-term trials yet.

METHODS

The Finerenone in Reducing Kidney Failure and Disease Progression in Diabetic Kidney Disease -(FIDELIO-DKD) trial aims to assess the efficacy and safety of finerenone compared to placebo at reducing clinically important renal and CV outcomes in T2D patients with CKD. FIDELIO-DKD is a randomized, double-blind, placebo-controlled, parallel-group, event-driven trial running in 47 countries with an expected duration of approximately 5.5 years. FIDELIO-DKD randomized 5,734 patients with an estimated glomerular filtration rate (eGFR) ≥25-<75 mL/min/1.73 m2 and albuminuria (urinary albumin-to-creatinine ratio ≥30-≤5,000 mg/g). The study has at least 90% power to detect a 20% reduction in the risk of primary outcome (overall two-sided significance level α = 0.05), the composite of time to first occurrence of kidney failure, a sustained decrease of eGFR ≥40% from baseline over at least 4 weeks, or renal death.

CONCLUSION

FIDELIO-DKD will determine whether an optimally treated cohort of T2D patients with CKD at high risk of renal and CV events will experience cardiorenal benefits with the addition of finerenone to their treatment regimen.

Aldosterone Modulates the Mechanistic Target of Rapamycin Signaling in Male Mice

Both mechanistic target of rapamycin (mTOR) pathway and aldosterone are implicated in the development of cardiovascular and renal disease. However, the interaction between aldosterone and the mTOR pathway is unknown. We hypothesized the following: that (i) increased aldosterone will modulate the activity of the mTORC1 and mTORC2 molecular pathways in the heart and kidney; (ii) a physiologic increase in aldosterone will affect these pathways differently than a pathophysiologic one; and (iii) the changes in the mTOR level/activity will differ between the heart and kidney. In both kidney and heart tissues, phosphorylation of mTOR is significantly decreased when aldosterone levels are physiologically increased (by dietary sodium restriction), followed by a decrease in phosphorylated p70S6K1 in cardiac, but not renal, tissue. Sirtuin 1, an epigenetic modulator, is decreased in the heart but increased in the kidney. Conversely, pathophysiologic aldosterone levels (an infusion for 3 weeks) had divergent effects on phosphorylated mTOR and the downstream substrates of mTORC1 and mTORC2 in cardiac and renal tissues. Increased aldosterone levels significantly alter mTOR activity in the heart and kidney. In the kidney, substantial differences were noted if the increase was produced physiologically vs pathophysiologically, suggesting that mTOR activity, in part, may mediate aldosterone-induced renal damage. Thus, modulating mTOR activity may reduce aldosterone-dependent renal damage similar to mineralocorticoid receptor blockade but potentially with less adverse side effects.

Mineralocorticoid receptor antagonists and kidney diseases: pathophysiological basis

Chronic kidney disease (CKD) represents a global health concern, and its prevalence is increasing. The ultimate therapeutic option for CKD is kidney transplantation. However, the use of drugs that target specific pathways to delay or halt CKD progression, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and sodium-glucose co-transporter-2 (SGLT-2) inhibitors is limited in clinical practice. Mineralocorticoid receptor activation in nonclassical tissues, such as the endothelium, smooth muscle cells, inflammatory cells, podocytes, and fibroblasts may have deleterious effects on kidney structure and function. Several preclinical studies have shown that mineralocorticoid receptor antagonists (MRAs) ameliorate or cure kidney injury and dysfunction in different models of kidney disease. In this review, we present the preclinical evidence showing a benefit of MRAs in acute kidney injury, the transition from acute kidney injury to CKD, hypertensive and diabetic nephropathy, glomerulonephritis, and kidney toxicity induced by calcineurin inhibitors. We also discuss the molecular mechanisms responsible for renoprotection related to MRAs that lead to reduced oxidative stress, inflammation, fibrosis, and hemodynamic alterations. The available clinical data support a benefit of MRA in reducing proteinuria in diabetic kidney disease and improving cardiovascular outcomes in CKD patients. Moreover, a benefit of MRAs in kidney transplantation has also been observed. The past and present clinical trials describing the effect of MRAs on kidney injury are presented, and the risk of hyperkalemia and use of other options, such as potassium binding agents or nonsteroidal MRAs, are also addressed. Altogether, the available preclinical and clinical data support a benefit of using MRAs in CKD, an approach that should be further explored in future clinical trials.

Mineralocorticoid Receptor and Cardiovascular Disease

Activation of the mineralocorticoid receptor (MR) in the distal nephron by its ligand, aldosterone, plays an important role in sodium reabsorption and blood pressure regulation. However, expression of the MR goes beyond the kidney. It is expressed in a variety of other tissues in which its activation could lead to tissue injury. Indeed, MR activation in the cardiovascular (CV) system has been shown to promote hypertension, fibrosis, and inflammation. Pharmacological blockade of the MR has protective effects in several animal models of CV disease. Furthermore, the use of MR antagonists is beneficial for heart failure patients, preventing mortality and morbidity. A better understanding of the implications of the MR in the setting of CV diseases is critical for refining treatments and improving patient care. The mechanisms involved in the deleterious effects of MR activation are complex and include oxidative stress, inflammation, and fibrosis. This review will discuss the pathological role of the MR in the CV system and the major mechanisms underlying it.

The role of novel biomarkers in predicting diabetic nephropathy: a review

Diabetic nephropathy (DN) is one of the microvascular complications of the kidney arising commonly from type 1 diabetes mellitus (T1DM), and occasionally from type 2 diabetes mellitus (T2DM). Microalbuminuria serves as an early indicator of DN risk and a predictor of its progression as well as cardiovascular disease risk in both T1DM and T2DM. Although microalbuminuria remains the gold standard for early detection of DN, it is not a sufficiently accurate predictor of DN risk due to some limitations. Thus, there is a paradigm shift to novel biomarkers which would help to predict DN risk early enough and possibly prevent the occurrence of end-stage kidney disease. These new biomarkers have been broadly classified into glomerular biomarkers, tubular biomarkers, biomarkers of inflammation, biomarkers of oxidative stress, and miscellaneous biomarkers which also include podocyte biomarkers, some of which are also considered as tubular and glomerular biomarkers. Although they are potentially useful for the evaluation of DN, current data still preclude the routine clinical use of majority of them. However, their validation using high-quality and large longitudinal studies is of paramount importance, as well as the subsequent development of a biomarker panel which can reliably predict and evaluate this renal microvascular disease. This paper aims to review the predictive role of these biomarkers in the evaluation of DN.

Randomized Controlled Trial of Mineralocorticoid Receptor Blockade in Children with Chronic Kidney Allograft Nephropathy

BACKGROUND AND OBJECTIVES

We showed that mineralocorticoid receptor blockade (MRB) prevented acute and chronic cyclosporine nephropathy (CsA-Nx) in the rat. The aim of this translational study was to investigate the effect of long-term eplerenone administration on renal allograft function in children with biopsy-proven chronic allograft nephropathy (CAN).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Renal transplant children <18 years, biopsy-proven CAN, and a GFR>40 ml/min per 1.73 m2 were included. Patients with BK virus active nephritis, recurrence of renal disease, GFR decline in previous 3 months, or treated with calcium antagonists or antifungal drugs were excluded. They were randomized to receive placebo (n=10) or eplerenone 25 mg/d for 24 months (n=13). Visits were scheduled at baseline, 6, 12, and 24 months. At each period, a complete clinical examination was performed and blood and urine samples were taken. Urine creatinine, 8-hydroxylated-guanosine, heat shock protein 72 (HSP72), and kidney injury molecule (KIM-1) levels were also assessed. In kidney biopsy samples, the tubulo-interstitial area affected by fibrosis (TIF) and glomerulosclerosis were measured at baseline and after 24 months.

RESULTS

The baseline eGFR was 80±6 in the placebo and 86±6 ml/min per 1.73 m2 in the eplerenone group; at 24 months it was 66±8 and 81±7 ml/min per 1.73 m2, respectively (P=0.33; 95% confidence intervals, -18 to 33 at baseline, and -11 to 40 after 24 months). The albumin-to-creatinine ratio was 110±74 in the placebo, and 265±140 mg/g in the eplerenone group; and after 24 months it was 276±140 and 228±88 mg/g, respectively (P=0.15; 95% confidence intervals, -283 to 593, and -485 to 391, respectively). In addition, the placebo exhibited a greater TIF, glomerulosclerosis, and urinary HSP72 compared with the eplerenone group.

CONCLUSIONS

Although this study was underpowered to provide definitive evidence that long-term eplerenone administration attenuates the progression of CAN in pediatric transplant patients, it encourages testing the potential benefit of MRB in this pediatric population.

Mineralocorticoid Receptor Signaling as a Therapeutic Target for Renal and Cardiac Fibrosis

Activation of the mineralocorticoid receptor (MR) plays important roles in both physiological and pathological events. Blockade of MR signaling with MR antagonists (MRAs) has been used clinically to treat kidney and cardiac disease associated with hypertension and other chronic diseases, resulting in suppression of fibrosis in these organs. However, the current use of steroidal MRAs has been limited by off target effects on other hormone receptors or adverse effects on kidney tubular function. In this review, we summarize recent insights into the profibrotic roles of MR signaling in kidney and cardiovascular disease. We review experimental in vitro data identifying the pathological mechanisms associated with MR signaling in cell types found in the kidney (mesangial cells, podocytes, tubular cells, macrophages, interstitial fibroblasts) and heart (cardiomyocytes, endothelial cells, vascular smooth muscle cells, macrophages). In addition, we demonstrate the in vivo importance of MR signaling in specific kidney and cardiac cell types by reporting the outcomes of cell type selective MR gene deletion in animal models of kidney and cardiac disease and comparing these findings to those obtained with MRAs treatment. This review also includes a discussion of the potential benefits of novel non-steroidal MRAs for targeting kidney and cardiac fibrosis compared to existing steroidal MRAs, as well as the possibility of novel combination therapies and cell selective delivery of MRAs.

Nonsteroidal Mineralocorticoid Receptor Antagonist Finerenone Protects Against Acute Kidney Injury-Mediated Chronic Kidney Disease: Role of Oxidative Stress

Acute kidney injury induced by ischemia/reperfusion (IR) is a frequent complication in hospitalized patients. Mineralocorticoid receptor antagonism has shown to be helpful against renal IR consequences; however, the potential benefit of novel nonsteroidal mineralocorticoid receptor antagonists such as finerenone has to be further explored. In this study, we evaluated the efficacy of finerenone to prevent the acute and chronic consequences of ischemic acute kidney injury. For the acute study (24 hours), 18 rats were divided into sham, bilateral renal ischemia of 25 minutes, and rats that received 3 doses of finerenone at 48, 24, and 1 hour before the ischemia. For the chronic study (4 months), 23 rats were divided into sham, rats that underwent 45 minutes of bilateral ischemia, and rats treated with finerenone at days 2 and 1 and 1 hour before IR. We found that after 24 hours of reperfusion, the untreated IR rats presented kidney dysfunction and tubular injury. Kidney injury molecule-1 and neutrophil gelatinase associated to lipolacin mRNA levels were increased. In contrast, the rats treated with finerenone displayed normal kidney function and significantly lesser tubular injury and kidney injury molecule-1 and neutrophil gelatinase associated to lipolacin levels. After 4 months, the IR rats developed chronic kidney disease, evidenced by kidney dysfunction, increased proteinuria and renal vascular resistance, tubular dilation, extensive tubule-interstitial fibrosis, and an increase in kidney transforming growth factor-β and collagen-I mRNA. The transition from acute kidney injury to chronic kidney disease was fully prevented by finerenone. Altogether, our data show that in the rat, finerenone is able to prevent acute kidney injury induced by IR and the chronic and progressive deterioration of kidney function and structure.

Effects of mineralocorticoid receptor antagonists on the progression of diabetic nephropathy

Aims/Introduction

We aimed to evaluate the potential benefits and adverse effects of adding a mineralocorticoid receptor antagonist (MRA) to angiotensin‐converting enzyme inhibitors (ACEI) and/or angiotensin receptor blockers (ARB), as standard treatment in patients with diabetic nephropathy.

Materials and Methods

We scanned the Embase, PubMed and Cochrane Central Register of Controlled Trials databases for human clinical trials published in English until June 2016, evaluating renal outcomes in patients with diabetic nephropathy.

Results

A total of 18 randomized controlled trials involving 1,786 patients were included. Compared with ACEI/ARB alone, co‐administration of MRA and ACEI/ARB significantly reduced urinary albumin excretion and the urinary albumin–creatinine ratio (mean difference −69.38, 95% confidence intervals −103.53 to −35.22, P < 0.0001; mean difference −215.74, 95% confidence intervals −409.22 to −22.26, P = 0.03, respectively). A decrease of blood pressure was also found in the co‐administration of MRA and ACEI/ARB groups. However, we did not observe any improvement in the glomerular filtration rate. There was a significant increase in the risk of hyperkalemia on the addition of MRA to ACEI/ARB treatment (relative risk 3.74, 95% confidence intervals 2.30–6.09, P < 0.00001).

Conclusions

These findings suggest that co‐administration of MRA and ACEI/ARB has beneficial effects on renal outcomes with increasing the incidence of hyperkalemia.

Emerging Roles of the Mineralocorticoid Receptor in Pathology: Toward New Paradigms in Clinical Pharmacology

The mineralocorticoid receptor (MR) and its ligand aldosterone are the principal modulators of hormone-regulated renal sodium reabsorption. In addition to the kidney, there are several other cells and organs expressing MR, in which its activation mediates pathologic changes, indicating potential therapeutic applications of pharmacological MR antagonism. Steroidal MR antagonists have been used for decades to fight hypertension and more recently heart failure. New therapeutic indications are now arising, and nonsteroidal MR antagonists are currently under development. This review is focused on nonclassic MR targets in cardiac, vascular, renal, metabolic, ocular, and cutaneous diseases. The MR, associated with other risk factors, is involved in organ fibrosis, inflammation, oxidative stress, and aging; for example, in the kidney and heart MR mediates hormonal tissue-specific ion channel regulation. Genetic and epigenetic modifications of MR expression/activity that have been documented in hypertension may also present significant risk factors in other diseases and be susceptible to MR antagonism. Excess mineralocorticoid signaling, mediated by aldosterone or glucocorticoids binding, now appears deleterious in the progression of pathologies that may lead to end-stage organ failure and could therefore benefit from the repositioning of pharmacological MR antagonists.

Re-Epithelialization of Pathological Cutaneous Wounds Is Improved by Local Mineralocorticoid Receptor Antagonism

Impaired cutaneous wound healing is a social burden. It occurs as a consequence of glucocorticoid treatment in several pathologies. Glucocorticoids (GC) bind not only to the glucocorticoid receptor but also to the mineralocorticoid receptor (MR), both expressed by keratinocytes. In addition to its beneficial effects through the glucocorticoid receptor, GC exposure may lead to inappropriate MR occupancy. We hypothesized that dermatological use of MR antagonists (MRA) might be beneficial by overcoming the negative impact of GC treatment on pathological wounds. The potent GC clobetasol, applied as an ointment to mouse skin, or added to cultured human skin explants, induced delayed wound closure and outgrowth of epidermis with reduced proliferation of keratinocytes. Delayed wound re-epithelialization was rescued by local MRA application. Normal skin was unaffected by MRA. The benefit of MR blockade is explained by the increased expression of MR in clobetasol-treated mouse skin. Blockade of the epithelial sodium channel by phenamil also rescued cultured human skin explants from GC-impaired growth of the epidermis. MRA application over post-biopsy wounds of clobetasol-treated skin zones of healthy volunteers (from the Interest of Topical Spironolactone's Administration to Prevent Corticoid-induced Epidermal Atrophy clinical trial) also accelerated wound closure. In conclusion, we propose repositioning MRA for cutaneous application to improve delayed wound closure occurring in pathology.

Hypothalamic-pituitary-adrenal axis activity is associated with the prevalence of chronic kidney disease in diabetic patients

Progression of chronic kidney disease (CKD) in diabetic patients can occur through enhanced hypothalamic-pituitary-adrenal (HPA) axis activity. The purpose of our study was to determine whether HPA axis activity influences the prevalence of CKD in patients with type 2 diabetes mellitus. Seventy-seven diabetic patients (mean age, 60 years) were enrolled. CKD was defined by K/DOQI criteria, and serum cortisol level was measured after the 1 mg overnight dexamethasone suppression test (F-DST). F-DST values were significantly negatively correlated with estimated glomerular filtration rate (eGFR), and significantly positively correlated with cystatin C level and spot urine albumin to creatinine ratio in simple and multiple regression analyses. The subjects were divided into 3 groups (low, middle, and high) according to the F-DST, and the odds for CKD were 8.7-fold (95% confidence interval 2.56 to 29.6, P=0.01) and 12.5-fold (95% confidence interval 3.3 to 47.9, P<0.001) higher in subjects in the middle and high groups than those in the low group, respectively. In multivariate regression analysis, subjects in the middle group and high group (compared to those in the low group) had 13.0-fold (95% confidence interval, 2.9 to 58.8 and P=0.001) and 14.7-fold (95% confidence interval, 2.8 to 78.5 and P=0.002), respectively, higher risk for CKD. In conclusion, F-DST values have a relationship with decreased eGFR and increased cystatin C or albumin excretion involved in CKD, and enhanced HPA axis activity may be an independent risk factor for CKD in patients with type 2 diabetes mellitus.

Suppression of Rapidly Progressive Mouse Glomerulonephritis with the Non-Steroidal Mineralocorticoid Receptor Antagonist BR-4628

BACKGROUND/AIM

Steroidal mineralocorticoid receptor antagonists (MRAs) are effective in the treatment of kidney disease; however, the side effect of hyperkalaemia, particularly in the context of renal impairment, is a major limitation to their clinical use. Recently developed non-steroidal MRAs have distinct characteristics suggesting that they may be superior to steroidal MRAs. Therefore, we explored the benefits of a non-steroidal MRA in a model of rapidly progressive glomerulonephritis.

METHODS

Accelerated anti-glomerular basement membrane (GBM) glomerulonephritis was induced in groups of C57BL/6J mice which received no treatment, vehicle or a non-steroidal MRA (BR-4628, 5mg/kg/bid) from day 0 until being killed on day 15 of disease. Mice were examined for renal injury.

RESULTS

Mice with anti-GBM glomerulonephritis which received no treatment or vehicle developed similar disease with severe albuminuria, impaired renal function, glomerular tuft damage and crescents in 40% of glomeruli. In comparison, mice which received BR-4628 displayed similar albuminuria, but had improved renal function, reduced severity of glomerular tuft lesions and a 50% reduction in crescents. The protection seen in BR-4628 treated mice was associated with a marked reduction in glomerular macrophages and T-cells and reduced kidney gene expression of proinflammatory (CCL2, TNF-α, IFN-γ) and profibrotic molecules (collagen I, fibronectin). In addition, treatment with BR-4626 did not cause hyperkalaemia or increase urine Na+/K+ excretion (a marker of tubular dysfunction).

CONCLUSIONS

The non-steroidal MRA (BR-4628) provided substantial suppression of mouse crescentic glomerulonephritis without causing tubular dysfunction. This finding warrants further investigation of non-steroidal MRAs as a therapy for inflammatory kidney diseases.