Spironolactone reduces oxidative stress in living donor kidney transplantation: a randomized controlled trial

Mineralocorticoid receptor blockage in kidney transplantation: too much of a good thing or not?

Although, kidney transplantation (KT) is the best treatment option for patients with end-stage kidney disease, long-term complications including chronic kidney allograft disease (CKAD) and major adverse cardiovascular events (MACE) are common. To decrease these complications new therapeutic options are necessary. Mineralocorticoid receptor antagonists (MRAs) are one of the promising drugs in this context. In the general population, MRAs had favorable effects on blood pressure regulation, MACE, proteinuria and progression of chronic kidney disease. In the context of KT, there are limited studies showing beneficial effects such as reducing proteinuria and oxidative stress. In this review, we performed a narrative review to assess the use and impact of MRAs in kidney transplant recipients. We found that in KTRs, MRAs are safe and they have favorable or neutral impact on blood pressure, glomerular filtration rate, urinary protein/albumin excretion, and oxidative stress. No data was found regarding major cardiovascular adverse events.

Diuretics for preventing and treating acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is a well-known complication of critical illnesses, significantly affecting morbidity and the risk of death. Diuretics are widely used to ameliorate excess fluid accumulation and oliguria associated with AKI. Their popularity stems from their ability to reduce the energy demands of renal tubular cells by inhibiting transporters and flushing out intratubular casts. Numerous studies have assessed the effects of diuretics in the context of AKI prevention and treatment. However, a comprehensive systematic review addressing this topic has yet to be conducted.

OBJECTIVES

This review aimed to explore the benefits and harms of diuretics for both the prevention and treatment of AKI.

SEARCH METHODS

The Cochrane Kidney and Transplant Register of Studies was searched up to May 2024 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) and quasi-RCTs in which diuretics were used to prevent or treat AKI.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data using standardised data extraction forms. Dichotomous outcomes were expressed as risk ratios (RR) with 95% confidence intervals (CI). Where continuous scales of measurement were used to assess the effects of treatment, the standardised mean difference (SMD) was used. The primary review outcomes for AKI prevention studies were the incidence of AKI and any use of kidney replacement therapy (KRT). For treatment studies, the primary outcome was any use of KRT. The certainty of evidence was assessed per outcome using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 64 studies (83 reports, 9871 participants): 53 prevention studies (8078 participants) and 11 treatment studies (1793 participants). Studies were conducted in the following World Health Organization regions: the Americas (15), Eastern Mediterranean (9), Europe (25), South-East Asia (2), and the Western Pacific (13). Thirty-six studies were single-centre studies, 19 were multicentre, and the setting was unclear in nine studies. Diuretics were compared to placebo, no treatment or conventional therapy, saline solutions (isotonic or hypotonic), 5% dextrose, 5% glucose, Hartmann's solution, and Ringer's acetate. Overall, the risk of bias was low in one study, high in 19 studies, and of some concern in 41 studies. Three studies could not be assessed because they did not report any outcomes of interest. For AKI prevention, compared to control, diuretics may reduce the risk of AKI (38 studies, 5540 participants: RR 0.75, 95%, CI 0.61 to 0.92; I2 = 77%; low-certainty evidence) and probably reduce any use of KRT (32 studies, 4658 participants: RR 0.63, 95% CI 0.43 to 0.91; I2 = 0%, moderate-certainty evidence) and death (33 studies, 6447 participants: RR 0.73, 95% CI 0.59 to 0.92; I2 = 0%; moderate-certainty evidence). The use of diuretics may result in little or no difference in the need for permanent dialysis (2 studies, 956 participants: RR 0.52, 95% CI 0.08 to 3.47; I2 = 21%; low-certainty evidence), hypotension (7 studies, 775 participants: RR 1.27, 95% CI 0.87 to 1.86; I2 = 0%; low-certainty evidence) and hypokalaemia (6 studies, 1383 participants: RR 1.20, 95% CI 0.88 to 1.73; I2 = 43%; low-certainty evidence), and had uncertain effects on arrhythmias (13 studies, 3375 participants: RR 0.77, 95% CI 0.57 to 1.04; I2 = 53%; very-low certainty evidence). Diuretics may make little or no difference to changes in SCr within 30 days (8 studies, 646 participants: SMD 0.41, 95% CI -0.01, to 0.83; I2 = 82%; low-certainty evidence) but it was uncertain whether diuretics increased urinary output (8 studies, 1155 participants: SMD 1.87, 95% CI -0.20 to 3.95; I2 = 99%; very low-certainty evidence). For AKI treatment, diuretics may make little or no difference to any use of KRT (8 studies, 1275 participants: RR 0.93, 95% CI 0.83 to 1.04; I2 = 2%; low-certainty evidence) or death (14 studies, 2052 participants: RR 1.08, 95% CI 0.96 to 1.22; I2 = 0%; low-certainty evidence). Diuretics may increase hypotension (2 studies, 720 participants: RR 1.99, 95% CI 1.16 to 3.41; I2 = 90%; low-certainty evidence) and probably increase arrhythmias (6 studies, 1011 participants: RR 1.62, 95% CI 1.12 to 2.33; I2 = 0%; moderate-certainty evidence). Diuretics may result in little or no difference in hypokalaemia (3 studies, 478 participants: RR 1.52, 95% CI 0.70 to 3.31; I2 = 0%; low-certainty evidence). It was uncertain whether diuretics increased urinary output (3 studies, 329 participants: SMD 4.40, 95% CI -0.94 to 9.74; I2 = 99%; very low-certainty evidence). The need for permanent dialysis and changes in serum creatinine were not reported.

AUTHORS' CONCLUSIONS

When used for the prevention of AKI, diuretics may reduce the risk of AKI. However, our confidence in the effect estimate is limited. Diuretics probably reduce the incidence of KRT use, and we are moderately confident in the effect estimate. When used for the treatment of AKI, diuretics may make little or no difference to any use of KRT, and our confidence in the effect estimate is limited. More RCTs are needed to explore the role of diuretics for treating established AKI.

Mineralocorticoid receptor antagonists in kidney transplantation

BACKGROUND

The fundamental role of the renin-angiotensin-aldosterone system in the pathophysiology of chronic kidney disease, congestive heart failure, hypertension and proteinuria is well established in pre-clinical and clinical studies. Mineralocorticoid receptor antagonists are among the primary options for renin-angiotensin-aldosterone system blockage, along with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers.

METHODS

In this narrative review, we aim to evaluate the efficiency and safety of mineralocorticoid receptor antagonists in kidney transplant recipients, including the potential underlying pathophysiology.

RESULTS

The efficiency and safety of mineralocorticoid receptor antagonists in managing chronic kidney disease and proteinuria, either non-nephrotic or nephrotic range, have been demonstrated among nontransplanted patients, though studies investigating the role of mineralocorticoid receptor antagonists among kidney transplant recipients are scarce. Nevertheless, promising results have been reported in pre-clinical and clinical studies among kidney transplant recipients regarding the role of mineralocorticoid receptor antagonists in terms of ischaemia-reperfusion injury, proteinuria, or calcineurin inhibitor-mediated nephrotoxicity without considerable adverse events such as hypotension, hyperkalaemia or worsening renal functions.

CONCLUSION

Even though initial results regarding the role of mineralocorticoid receptor antagonist therapy for kidney transplant recipients are promising, there is clear need for large-scale randomized clinical trials with long-term follow-up data.

Antihypertensive treatment for kidney transplant recipients

BACKGROUND

The comparative effects of specific blood pressure (BP) lowering treatments on patient-important outcomes following kidney transplantation are uncertain. Our 2009 Cochrane review found that calcium channel blockers (CCBs) improved graft function and prevented graft loss, while the evidence for other BP-lowering treatments was limited. This is an update of the 2009 Cochrane review.

OBJECTIVES

To compare the benefits and harms of different classes and combinations of antihypertensive drugs in kidney transplant recipients.

SEARCH METHODS

We contacted the Information Specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 3 July 2024 using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs evaluating any BP-lowering agent in recipients of a functioning kidney transplant for at least two weeks were eligible.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risks of bias and extracted data. Treatment estimates were summarised using the random-effects model and expressed as relative risk (RR) or mean difference (MD) with 95% confidence intervals (CI). Evidence certainty was assessed using Grades of Recommendation, Assessment, Development and Evaluation (GRADE) processes. The primary outcomes included all-cause death, graft loss, and kidney function.

MAIN RESULTS

Ninety-seven studies (8706 participants) were included. One study evaluated treatment in children. The overall risk of bias was unclear to high across all domains. Compared to placebo or standard care alone, CCBs probably reduce all-cause death (23 studies, 3327 participants: RR 0.83, 95% CI 0.72 to 0.95; I2 = 0%; moderate certainty evidence) and graft loss (24 studies, 3577 participants: RR 0.84, 95% CI 0.75 to 0.95; I2 = 0%; moderate certainty evidence). CCBs may make little or no difference to estimated glomerular filtration rate (eGFR) (11 studies, 2250 participants: MD 1.89 mL/min/1.73 m2, 95% CI -0.70 to 4.48; I2 = 48%; low certainty evidence) and acute rejection (13 studies, 906 participants: RR 10.8, 95% CI 0.85 to 1.35; I2 = 0%; moderate certainty evidence). CCBs may reduce systolic BP (SBP) (3 studies, 329 participants: MD -5.83 mm Hg, 95% CI -10.24 to -1.42; I2 = 13%; low certainty evidence) and diastolic BP (DBP) (3 studies, 329 participants: MD -3.98 mm Hg, 95% CI -5.98 to -1.99; I2 = 0%; low certainty evidence). CCBs have uncertain effects on proteinuria. Compared to placebo or standard care alone, angiotensin-converting-enzyme inhibitors (ACEi) may make little or no difference to all-cause death (7 studies, 702 participants: RR 1.13, 95% CI 0.58 to 2.21; I2 = 0%; low certainty evidence), graft loss (6 studies, 718 participants: RR 0.75, 95% CI 0.49 to 1.13; I2 = 0%; low certainty evidence), eGFR (4 studies, 509 participants: MD -2.46 mL/min/1.73 m2, 95% CI -7.66 to 2.73; I2 = 64%; low certainty evidence) and acute rejection (4 studies, 388 participants: RR 1.75, 95% CI 0.76 to 4.04; I2 = 0%; low certainty evidence). ACEi may reduce proteinuria (5 studies, 441 participants: MD -0.33 g/24 hours, 95% CI -0.64 to -0.01; I2 = 67%; low certainty evidence) but had uncertain effects on SBP and DBP. Compared to placebo or standard care alone, angiotensin receptor blockers (ARB) may make little or no difference to all-cause death (6 studies, 1041 participants: RR 0.69, 95% CI 0.36 to 1.31; I2 = 0%; low certainty evidence), eGRF (5 studies, 300 participants: MD -1.91 mL/min/1.73 m2, 95% CI -6.20 to 2.38; I2 = 57%; low certainty evidence), and acute rejection (4 studies, 323 participants: RR 1.00, 95% CI 0.44 to 2.29; I2 = 0%; low certainty evidence). ARBs may reduce graft loss (6 studies, 892 participants: RR 0.35, 95% CI 0.15 to 0.84; I2 = 0%; low certainty evidence), SBP (10 studies, 1239 participants: MD -3.73 mm Hg, 95% CI -7.02 to -0.44; I2 = 63%; moderate certainty evidence) and DBP (9 studies, 1086 participants: MD -2.75 mm Hg, 95% CI -4.32 to -1.18; I2 = 47%; moderate certainty evidence), but has uncertain effects on proteinuria. The effects of CCBs, ACEi or ARB compared to placebo or standard care alone on cardiovascular outcomes (including fatal or nonfatal myocardial infarction, fatal or nonfatal stroke) or other adverse events were uncertain. The comparative effects of ACEi plus ARB dual therapy, alpha-blockers, and mineralocorticoid receptor antagonists compared to placebo or standard care alone were rarely evaluated. Head-to-head comparisons of ACEi, ARB or thiazide versus CCB, ACEi versus ARB, CCB or ACEi versus alpha- or beta-blockers, or ACEi plus CCB dual therapy versus ACEi or CCB monotherapy were scarce. No studies reported outcome data for cancer or life participation.

AUTHORS' CONCLUSIONS

For kidney transplant recipients, the use of CCB therapy to reduce BP probably reduces death and graft loss compared to placebo or standard care alone, while ARB may reduce graft loss. The effects of ACEi and ARB compared to placebo or standard care on other patient-centred outcomes were uncertain. The effects of dual therapy, alpha-blockers, and mineralocorticoid receptor antagonists compared to placebo or standard care alone and the comparative effects of different treatments were uncertain.

Effect of Spironolactone on Kidney Function in Kidney Transplant Recipients (the SPIREN trial): A Randomized Placebo-Controlled Clinical Trial

Key Points

Spironolactone is safe for kidney transplant patients. Spironolactone reduces kidney function by an acute effect, whereafter it remains stable. Spironolactone does not affect the progression of interstitial fibrosis in protocol biopsies.

Background

Long-term kidney allograft survival is hampered by progressive interstitial fibrosis and tubular atrophy. The SPIREN trial tested the hypothesis that the mineralocorticoid receptor antagonist spironolactone stabilizes kidney function and attenuates glomerular barrier injury in kidney transplant patients treated with calcineurin inhibitors.

Methods

We conducted a randomized, placebo-controlled, double-blind clinical trial including 188 prevalent kidney transplant patients. Patients were randomized to spironolactone or placebo for 3 years. GFR was measured along with proteinuria and kidney fibrosis. The primary end point was change in measured GFR. Secondary outcomes were 24-hour proteinuria, kidney allograft fibrosis, and cardiovascular events. Measured GFRs, 24-hour proteinuria, and BP were determined yearly. Kidney biopsies were collected at baseline and after 2 years (n =48). Fibrosis was evaluated by quantitative stereology and classified according to Banff.

Results

The groups were comparable at baseline except for slightly older allografts in the spironolactone group. Spironolactone reduced measured GFRs (up to –7.6 [95% confidence interval, −10.9 to −4.3] ml/min compared with placebo) independently of time since transplantation and BP with no effect on the kidney function curve over time and reduced 24-hour proteinuria after 1 year. There was no significant effect of spironolactone on the development of interstitial fibrosis.

Conclusions

Spironolactone added to standard therapy for 3 years in kidney transplant patients did not improve kidney function, long-term proteinuria, or interstitial fibrosis.

Clinical Trial registration number

NCT01602861 .

Spironolactone for Preventing Contrast-Induced Nephropathy After Percutaneous Coronary Intervention in Patients With Acute Myocardial Infarction and Chronic Kidney Disease

Patients with acute myocardial infarction (AMI) and chronic kidney disease (CKD) are at high risk of contrast-induced nephropathy (CIN), which can subsequently worsen the overall prognosis. To evaluate the efficacy of spironolactone for CIN prevention, 410 patients with AMI and CKD receiving percutaneous coronary intervention (PCI) were retrospectively analyzed. Among them, 240 and 170 patients were enrolled in the standard treatment and spironolactone groups (spironolactone was administered 2 days before and 3 days after PCI), respectively. The primary endpoint of CIN was defined as a 0.5 mg/dL or >25% increase from the baseline serum creatinine level within 48-72 h post-PCI. CIN incidence was significantly lower in the spironolactone group than in the standard treatment group (11.2 vs 26.7%, P < .001). Further, cardiac re-hospitalization (hazard ratio [HR]: 0.515; 95% CI: 0.382-0.694; P < .001) and cardiac death (HR: 0.612; 95% CI: 0.429-0.872; P = .007) risks were significantly lower in patients who received long-term spironolactone with a median treatment duration of 42 months after discharge. Spironolactone might lower the risk of CIN, and long-term use of spironolactone reduces the risk of cardiac re-hospitalization and cardiac death in patients with AMI and CKD undergoing PCI.

Potassium canrenoate in brain-dead organ donors: a randomised controlled clinical trial protocol (CANREO-PMO)

INTRODUCTION

Ischaemia/reperfusion injuries (IRIs) are associated with poorer survival of kidney grafts from expanded criteria donors. Preclinical studies have shown that mineralocorticoid receptor antagonists (MRAs) prevent acute and chronic post-ischaemic renal dysfunction by limiting IRI. However, data concerning the safety of MRAs in brain-dead donor patients are scarce. We seek to investigate the tolerance of MRAs on the haemodynamics in this population.

METHODS AND ANALYSIS

CANREO-PMO is a randomised, controlled, single-centre, double-blind study. Brain-dead organ donors hospitalised in intensive care are randomised 1:1 after consent to receive 200 mg potassium canrenoate or its matching placebo every 6 hours until organ procurement. The primary outcome is a hierarchical composite endpoint that includes: (1) cardiocirculatory arrest, (2) the impossibility of kidney procurement, (3) the average hourly dose of norepinephrine/epinephrine between randomisation and departure to the operating room, and (4) the average hourly volume of crystalloids and/or colloids received. Thirty-six patients will be included. The secondary endpoints evaluated among the graft recipients are the: (1) vital status of the kidney graft recipients and serum creatinine level with estimated glomerular filtration rate (GFR) according to Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) at 3 months after renal transplantation, (2) percentage of patients dependent on dialysis and/or with an estimated GFR <20 mL/min/1.73 m2 at 3 months, (3) vital status of the kidney graft recipients at 3 months, and (4) vital status of the kidney graft recipients and creatinine levels (in μmol/L), with the estimated GFR according to CKD-EPI (in mL/min/1.73 m2), at 1 year, 3 years and 10 years after transplantation.

ETHICS AND DISSEMINATION

This trial has full ethical approval (Comité de Protection des Personnes: CPP Ouest II-ANGERS, France), and the written consent of relatives will be obtained. Results will be reported at conferences, peer-reviewed publications and using social media channels.

TRIAL REGISTRATION NUMBER

NCT04714710.

Long-term effect of eplerenone treatment in children with chronic allograft nephropathy

BACKGROUND

Literature supports the protective role of mineralocorticoid antagonist (MRA) against the renal injury induced by aldosterone in kidney transplant recipients. However, there is limited data available regarding the safety and efficacy of MRAs in pediatric renal transplant patients. Therefore, we aimed to investigate the effect of long-term eplerenone administration in children with chronic allograft nephropathy (CAN).

METHODS

Twenty-six renal transplant children with biopsy-proven CAN, an estimated glomerular filtration rate (eGFR ) > 40 mL/min per 1.73 m2 and with a significant proteinuria were included. Selected patients were randomly divided into two groups as follows; Group 1 (n = 10) patients received 25 mg/day eplerenone and Group 2 (n = 16) patients did not receive eplerenone for 36 months. Patients were examined in the renal transplant outpatient clinic biweekly for the first month and once a month thereafter. The primary outcome of the patients was compared.

RESULTS

Mean eGFR stayed stable in group 1 patients, but significantly decreased in group 2 at 36 months (57.53 ± 7.53 vs. 44.94 ± 8.04 mL/min per 1.73 m2 , p = .001). Similarly, spot protein-creatinine ratio was significantly lower in group 1 compared to group 2 patients at 36 months (1.02 ± 7.53 vs. 3.61 ± 0.53, p < .001). Eplerenone associated hyperkalemia was not observed in group 1 patients (4.6 ± 0.2 vs. 4.56 ± 0.3, p = .713).

CONCLUSION

The long-term eplerenone administration blunted the chronic allograft nephropathy by maintaining a stable eGFR levels and decreasing urine protein-creatinine ratio. Eplerenone associated hyperkalemia was not observed in our study.

Renal, but not platelet or skin, extracellular vesicles decrease oxidative stress, enhance nascent peptide synthesis, and protect from ischemic renal injury

Acute kidney injury (AKI) is deadly and expensive, and specific, effective therapy remains a large unmet need. We have demonstrated the beneficial effects of transplanted adult tubular cells and extracellular vesicles (EVs; exosomes) derived from those renal cells on experimental ischemic AKI, even when administered after renal failure is established. To further examine the mechanisms of benefit with renal EVs, we tested the hypothesis that EVs from other epithelia or platelets (a rich source of EVs) might be protective, using a well-characterized ischemia-reperfusion model. When given after renal failure was present, renal EVs, but not those from skin or platelets, markedly improved renal function and histology. The differential effects allowed us to examine the mechanisms of benefit with renal EVs. We found significant decreases in oxidative stress postischemia in the renal EV-treated group with preservation of renal superoxide dismutase and catalase as well as increases in anti-inflammatory interleukin-10. In addition, we propose a novel mechanism of benefit: renal EVs enhanced nascent peptide synthesis following hypoxia in cells and in postischemic kidneys. Although EVs have been used therapeutically, these results serve as "proof of principle" to examine the mechanisms of injury and protection.NEW & NOTEWORTHY Acute kidney injury is common and deadly, yet the only approved treatment is dialysis. Thus, a better understanding of injury mechanisms and potential therapies is needed. We found that organ-specific, but not extrarenal, extracellular vesicles improved renal function and structure postischemia when given after renal failure occurred. Oxidative stress was decreased and anti-inflammatory interleukin-10 increased with renal, but not skin or platelet, exosomes. We also propose enhanced nascent peptide synthesis as a novel protective mechanism.

Repeated Episodes of Ischemia/Reperfusion Induce Heme-Oxygenase-1 (HO-1) and Anti-Inflammatory Responses and Protects against Chronic Kidney Disease

Preconditioning episodes of ischemia/reperfusion (IR) induce protection against acute kidney injury (AKI), however their long-term effect still unknown. We evaluated AKI to chronic kidney disease (CKD) transition, after three-mild or three-severe episodes of IR. AKI was induced by single bilateral IR (1IR), or three episodes of IR separated by 10-day intervals (3IR) of mild (20 min) or severe (45 min) ischemia. Sham-operated rats served as controls. During 9-months, the 1IR group (20 or 45 min) developed CKD evidenced by progressive proteinuria and renal fibrosis. In contrast, the long-term adverse effects of AKI were markedly ameliorated in the 3IR group. The acute response in 3IR, contrasted with the 1IR group, that was characterized by an increment in heme oxygenase-1 (HO-1) and an anti-inflammatory response mediated by a NFkB-p65 phosphorylation and IL-6 decrease, together with an increase in TGF-β, and IL-10 expression, as well as in M2-macrophages. In addition, three episodes of IR downregulated endoplasmic reticulum (ER) stress markers expression, CHOP and BiP. Thus, repeated episodes of IR with 10-day intervals induced long-term renal protection accompanied with HO-1 overexpression and M2-macrophages increase.

Mineralocorticoid interaction with glycated albumin downregulates NRF - 2 signaling pathway in renal cells: Insights into diabetic nephropathy

In diabetic nephropathy, hyperglycemia elevates albumin glycation and also results in increased plasma aldosterone. Both glycation and aldosterone are reported to cause oxidative stress by downregulating the NRF-2 pathway and thereby resulting in reduced levels of antioxidants and glycation detoxifying enzymes. We hypothesize that an interaction between aldosterone and glycated albumin may be responsible for amplified oxidative stress and concomitant renal cell damage. Hence, human serum albumin was glycated by methylglyoxal (MGO) in presence of aldosterone. Different structural modifications of albumin, functional modifications and aldosterone binding were analyzed. HEK-293 T cells were treated with aldosterone+glycated albumin along with inhibitors of receptors for mineralocorticoid (MR) and advanced glycation endproducts (RAGE). Cellular MGO content, antioxidant markers (nitric oxide, glutathione, catalase, superoxide dismutase, glutathione peroxidase), detoxification enzymes (aldose reductase, Glyoxalase I, II), their expression along with NRF-2 and Keap-1 were measured. Aldosterone binds to albumin with high affinity which is static and spontaneous. Cell treatment by aldosterone+glycated albumin increased intracellular MGO, MR and RAGE expression; hampered antioxidant, detoxification enzyme activities and reduced NRF-2, Keap-1 expression. Thus, the glycated albumin-aldosterone interaction and its adverse effect on renal cells were confirmed. The results will help in developing better pharmacotherapeutic strategies for diabetic nephropathy.

Upregulation of Mineralocorticoid Receptor Contributes to Development of Salt-Sensitive Hypertension after Ischemia-Reperfusion Injury in Rats

The ischemia-reperfusion injury (IRI) of rat kidneys is used as a model of acute kidney injury. Salt-sensitive hypertension occurs in rats after IRI, and the distal nephrons play important roles in the development of this condition. We investigated the role of the mineralocorticoid receptor (MR) in the progression of IRI-induced salt-sensitive hypertension in rats. Fourteen days after right-side nephrectomy, IRI was induced by clamping the left renal artery, with sham surgery performed as a control. IRI rats were provided with normal water or water with 1.0% NaCl (IRI/NaCl), or they were implanted with an osmotic mini-pump to infuse vehicle or aldosterone (IRI/Aldo). Esaxerenone, a non-steroidal MR blocker (MRB), was administered to IRI/NaCl and IRI/Aldo rats for 6 weeks. MR expression increased by day 7 post-IRI. Blood pressure and urinary protein excretion increased in IRI/NaCl and IRI/Aldo rats over the 6-week period, but these effects were negated by MRB administration. The MRB attenuated the expression of the gamma-epithelial sodium channel (ENaC) and renal damage. The ENaC inhibitor, amiloride, ameliorated hypertension and renal damage in IRI/NaCl and IRI/Aldo rats. Our findings thus showed that MR upregulation may play a pivotal role in ENaC-mediated sodium uptake in rats after IRI, resulting in the development of salt-sensitive hypertension in response to salt overload or the activation of the renin-angiotensin-aldosterone system.

Transient response of serpinA3 during cellular stress

We demonstrated that serpinA3c/k relocates from the cytoplasm to the apical tubular membrane (ATM) in chronic kidney disease (CKD), suggesting its secretion in luminal space in pathophysiological contexts. Here, we studied serpinA3c/k expression and secretion under different stressful conditions in vitro and in vivo. HEK-293 cells were transfected with a FLAG-tagged serpinA3c/k clone and exposed to H₂ O₂ or starvation. Both stressors induced serpinA3c/k secretion but with a higher molecular weight. Glycanase treatment established that serpinA3c/k is glycosylated. Site-directed mutagenesis for each of the four glycosylation sites was performed. During cellular stress, serpinA3c/k secretion increased with each mutant except in the quadruple mutant. In rats and patients suffering acute kidney injury (AKI), an atypical urinary serpinA3c/k excretion (uSerpinA3c/k) was observed. In rats with AKI, the greater the induced kidney damage, the greater the uSerpinA3 c/k, together with relocation toward ATM. Our findings show that: (1) serpinA3c/k is glycosylated and secreted, (2) serpinA3c/k secretion increases during cellular stress, (3) its appearance in urine reveals a pathophysiological state, and (4) urinary serpinA3 excretion could become a potential biomarker for AKI.

Mineralocorticoid receptor blockade with spironolactone has no direct effect on plasma IL-17A and injury markers in urine from kidney transplant patients

Kidney transplantation is associated with increased risk of cardiovascular morbidity. Interleukin-17A (IL-17A) mediates kidney injury. Aldosterone promotes T-helper-17 (Th-17) lymphocyte differentiation and IL-17A production through the mineralocorticoid receptor (MR). In this exploratory, post-hoc substudy, it was hypothesized that 1-year intervention with the MR antagonist spironolactone lowers IL-17A and related cytokines and reduces epithelial injury in kidney transplant recipients. Plasma and urine samples were obtained from kidney transplant recipients from a double-blind randomized clinical trial testing spironolactone (n=39) versus placebo (n=41). Plasma concentrations of cytokines IFN-γ, IL-17A, TNF-α, IL-6, IL-1β, and IL-10 were determined before and after 1-year treatment. Urine calbindin, clusterin, KIM-1, osteoactivin, TFF3, and VEGF/creatinine ratios were analyzed. Blood pressure and plasma aldosterone concentration at inclusion did not relate to plasma cytokines and injury markers. None of the cytokines changed in plasma after spironolactone intervention. Plasma IL-17A increased in the placebo group. Spironolactone induced an increase in plasma K⁺ (0.4 ± 0.4 mmol/L). This increase did not correlate with plasma IL-17A or urine calbindin and TFF3 changes. Ongoing treatment at inclusion with angiotensin-converting-enzyme inhibitor and/or angiotensin II receptor blockers was not associated with changed levels of IL-17A and injury markers and had no effect on the response to spironolactone. Urinary calbindin and TFF3 decreased in the spironolactone group with no difference in between-group analyses. In conclusion, irrespective of ongoing ANGII inhibition, spironolactone has no effect on plasma IL-17A and related cytokines or urinary injury markers in kidney transplant recipients.

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.

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.

Kidney Allograft Fibrosis: Diagnostic and Therapeutic Strategies

Interstitial fibrosis with tubule atrophy (IF/TA) is the response to virtually any sustained kidney injury and correlates inversely with kidney function and allograft survival. IF/TA is driven by various pathways that include hypoxia, renin-angiotensin-aldosterone system, transforming growth factor (TGF)-β signaling, cellular rejection, inflammation and others. In this review we will focus on key pathways in the progress of renal fibrosis, diagnosis and therapy of allograft fibrosis. This review discusses the role and origin of myofibroblasts as matrix producing cells and therapeutic targets in renal fibrosis with a particular focus on renal allografts. We summarize current trends to use multi-omic approaches to identify new biomarkers for IF/TA detection and to predict allograft survival. Furthermore, we review current imaging strategies that might help to identify and follow-up IF/TA complementary or as alternative to invasive biopsies. We further discuss current clinical trials and therapeutic strategies to treat kidney fibrosis.Supplemental Visual Abstract; http://links.lww.com/TP/C141.