Revisiting RAAS blockade in CKD with newer potassium-binding drugs

Innovative therapeutics for renoprotection: Where we are

Chronic kidney disease (CKD) has become highly prevalent worldwide, with major implications for public health, including increased risk of progression to kidney failure, cardiovascular events, and mortality. Up to a decade ago, renin-angiotensin system inhibitors, that is angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor blockers, were the only available pharmacological interventions to slow kidney function loss and limit the associated cardiovascular morbidity and mortality in this context. More recently, landmark trials have demonstrated the ability of novel therapeutics to significantly ameliorate kidney and cardiovascular outcomes in patients with CKD, when added on top of optimized renin-angiotensin system blockade. These include sodium-glucose cotransporter-2 inhibitors in patients with diabetic and nondiabetic kidney disease, as well as the nonsteroidal mineralcorticoid receptor antagonist finerenone and the glucagon-like peptide-1 receptor agonist semaglutide in patients with diabetic kidney disease. We herein review the evolving scenario and the latest evidence for the treatment of CKD, mainly focusing on proteinuric CKD. We started with a presentation of established and more recently approved classes of kidney protective drugs, followed by a discussion of therapeutic interventions under clinical investigation to slow CKD progression. Finally, we underscore the added value of personalized and multidrug interventions, which are becoming increasingly more feasible with the availability of a growing number of kidney protective agents, and are likely to stand as the most powerful tools to safely slow, or even prevent, the progression of proteinuric CKD. SIGNIFICANCE STATEMENT: Chronic kidney disease (CKD) is highly prevalent globally, and is associated with substantial morbidity and mortality. This review provides a comprehensive overview of the currently approved and emerging therapeutic options for the treatment of proteinuric CKD. As novel kidney protective agents have recently become available, the outcomes of patients with CKD could hopefully improve over the few decades ahead.

A network toxicology and machine learning approach to investigate the mechanism of kidney injury from melamine and cyanuric acid co-exposure

BACKGROUND

Within the past two decades, high-profile cases of melamine (MA) exposure have raised significant toxicological concerns, particularly regarding food adulteration. While widely used as a fundamental organic chemical intermediate in various household products, MA's potential for unexpected toxicological synergy with its homolog, cyanuric acid (CA), remains a concern. This study aimed to investigate the nephrotoxicity of combined melamine and cyanuric acid (MC) exposure and its underlying mechanisms in rats through an integrative approach, combining network toxicology (NT), bioinformatics, and experimental validation.

MATERIALS AND METHODS

Rats were exposed to MC at doses of 0/0 mg/kg/day (Control) and 63/63 mg/kg/day (MC) for four weeks. Kidney pathology, injury markers, and RNA sequencing (RNA-seq) data were analyzed to identify differentially expressed genes between the two groups. Bioinformatics analysis, including pathway enrichment and immune microenvironment analysis, was conducted to elucidate the underlying mechanisms of MC-induced kidney injury. Potential target proteins were identified using ChEMBL, STITCH, and GeneCards databases, and hub genes were screened using three machine learning algorithms: LASSO regression, Random Forest, and Molecular Complex Detection. Molecular docking simulations were performed to assess the interactions between MC and the identified hub genes.

RESULTS

MC exposure resulted in severe kidney morphological and histological changes, as well as elevated levels of kidney injury and fibrosis markers. RNA-seq analysis revealed significant enrichment of immuno-inflammatory and apoptosis-related pathways in the MC group. Immune microenvironment analysis confirmed the infiltration of pro-inflammatory immune cells. Network toxicology analysis identified 20 potential targets associated with MC-induced kidney injury. Two hub genes, Ren and Casp3, were identified as key regulators of the renin-angiotensin-aldosterone system (RAAS) activation and apoptosis, respectively. Further experimental validation, including Western blotting and immunofluorescence, confirmed the upregulation of these proteins. Molecular docking simulations demonstrated strong binding affinities between MC and the two hub proteins.

CONCLUSION

MC exposure induces significant kidney injury and fibrosis. The activation of the RAAS pathway and apoptosis plays a crucial role in MC-mediated nephrotoxicity. However, additional vivo experimental validation is lacking. Future studies should focus on further exploration for the mechanism of MC-induced nephrotoxicity and more rigorous experimental validation.

Comparative Efficacy and Safety of Angiotensin-Converting Enzyme Inhibitors, Angiotensin Receptor Blockers, and Calcium Channel Blockers in Hypertensive Patients With Chronic Kidney Disease: A Systematic Review

This systematic review evaluates the comparative efficacy and safety of antihypertensive therapies, including angiotensin-converting enzyme inhibitors (ACEis), angiotensin receptor blockers (ARBs), and calcium channel blockers (CCBs), in managing hypertension among chronic kidney disease (CKD) patients. A comprehensive search adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted across five databases, identifying eight randomized controlled trials (RCTs) published in the last five years. The included studies examined diverse populations, ranging from pediatric to elderly CKD patients, with interventions tailored to specific subgroups, including those with proteinuria or diabetic kidney disease. Key outcomes assessed included changes in estimated glomerular filtration rate (eGFR), proteinuria reduction, cardiovascular events, and treatment-related adverse effects. Findings highlighted the superiority of ACEis and ARBs in reducing proteinuria and slowing CKD progression, particularly in proteinuric patients, while CCBs were effective in blood pressure control and improving cardiovascular parameters. However, no head-to-head trials directly comparing renin-angiotensin-aldosterone system (RAAS) inhibitors (ACEis/ARBs) and CCBs were identified, limiting definitive conclusions regarding their relative efficacy. Limitations such as small sample sizes and short follow-up durations were also noted in some studies. This review underscores the importance of individualized therapy based on patient-specific factors to optimize renal and cardiovascular outcomes. Further research is recommended to explore long-term outcomes and combination therapies in this population.

Sanqi oral solution ameliorates renal fibrosis by suppressing fibroblast activation via HIF-1α/PKM2/glycolysis pathway in chronic kidney disease

ETHNOPHARMACOLOGICAL RELEVANCE

Sanqi oral solution (SQ) is a traditional Chinese patent medicine, widely used to treat chronic kidney diseases (CKD) in the clinic in China. Previous studies have confirmed its anti-renal fibrosis effect, but the specific pharmacological mechanism is still unclear.

AIM OF THE STUDY

Focusing on energy metabolism in fibroblasts, the renoprotective mechanism of SQ was investigated in vitro and in vivo.

METHODS

Firstly, the fingerprint of SQ was constructed and its elementary chemical composition was analyzed. In the 5/6Nx rats experiment, the efficacy of SQ on the kidney was evaluated by detecting serum and urine biochemical indexes and pathological staining of renal tissues. Lactic acid and pyruvic acid levels in serum and renal tissues were detected. PCNA protein expression in kidney tissue was detected by immunofluorescence assay and Western blot. Expression levels of HIF-1α, PKM2 and HK2 were determined by immunohistochemistry, Western blot or RT-qPCR assay. In addition, the effect of SQ intervention on cell proliferation and glycolysis was evaluated in TGF-β1-induced NRK-49F cells, and the role of SQ exposure and HIF-1α/PKM2/glycolysis pathway were further investigated by silencing and overexpressing HIF-1α gene in NRK-49F cells.

RESULTS

In 5/6 Nx rats, SQ effectively improved renal function and treated renal injury. It reduced the levels of lactic acid and pyruvic acid in kidney homogenates from CKD rats and decreased the expression levels of HIF-1α, PKM2, HK2, α-SMA, vimentin, collagen I and PCNA in kidney tissues. Similar results were observed in vitro. SQ inhibited NRK-49F cell proliferation, glycolysis and the expression levels of HIF-1α, PKM2 induced by TGF-β1. Furthermore, we established NRK-49F cells transfected with siRNA or pDNA to silence or overexpress the HIF-1α gene. Overexpression of HIF-1α promoted cellular secretion of lactic acid and pyruvic acid in TGF-β1-induced NRK-49F cells, however, this change was reversed by intervention with SQ or silencing the HIF-1α gene. Overexpression of HIF-1α can further induce increased PKM2 expression, while SQ intervention can reduce PKM2 expression. Moreover, PKM2 expression was also inhibited after silencing HIF-1α gene, and SQ was not effective even when given.

CONCLUSION

The mechanism of action of SQ was explored from the perspective of energy metabolism, and it was found to regulate PKM2-activated glycolysis, inhibit fibroblast activation, and further ameliorate renal fibrosis in CKD by targeting HIF-1α.

Management of hyperkalemia: Expert consensus from Kuwait - a Modified Delphi Approach

Introduction

Hyperkalemia is common in heart failure (HF) patients on renin angiotensin aldosterone inhibitors (RAASi), in chronic kidney disease (CKD), and in hemodialysis, and it negatively impacts their management. New potassium binders, such as sodium zirconium cyclosilicate (SZC), are effective in management of acute and chronic hyperkalemia. However, guidelines inconsistencies and lack of standardized treatment protocols are hindering proper and wider use of such agents. Therefore, an expert panel from Kuwait developed a consensus statement to address hyperkalemia management in acute settings, in HF, in CKD, and in hemodialysis.

Methods

A three-step modified Delphi method was adopted to develop the present consensus, which consisted of two rounds of voting and in-between a virtual meeting. Twelve experts from Kuwait participated in this consensus. Statements were developed and shared with experts for voting. A meeting was held to discuss statements that did not reach consensus at the first round and then the remaining statements were shared for final voting.

Results

The consensus consists of 44 statements involving an introduction to and the management of hyperkalemia in acute settings, HF, CKD, and hemodialysis. Thirty-six statements approved unanimously in the first vote. In the second vote, four statements were removed and four were approved after editing.

Conclusion

Hyperkalemia management lacks standardized definitions, treatment thresholds and consistent guidelines and laboratory practices. This consensus is in response to lack of standardized treatment in the Arabian Gulf, and it aims to establish guidance on hyperkalemia management for healthcare practitioners in Kuwait and highlight future needs.

Clinical Outcomes of Renin-Angiotensin-Aldosterone Blockade in Patients With Advanced Chronic Kidney Disease: A Systematic Review and Meta-analysis

BACKGROUND

The cardiovascular and renal benefits of renin-angiotensin aldosterone system (RAAS) blockade are not well established in patients with advanced chronic kidney disease (CKD). We conducted a systematic review and meta-analysis to identify potential risks and benefits from RAAS blockade in patients with CKD stage 4-5.

METHODS

A Medline search from inception to November 2022 was conducted to identify randomised controlled trials (RCTs) in patients with CKD stage 4-5 (estimated glomerular filtration rate ≤ 30 mL/min/1.73 m2) comparing RAAS blockade vs placebo or alternative antihypertensive therapy. Different intervention strategies were assessed (RAAS use vs nonuse, initiation vs placebo/alternative therapy, or discontinuation vs continuation). The primary outcome was progression to end-stage kidney disease (ESKD). Secondary outcomes were all-cause mortality and major adverse cardiovascular events (MACE). The risk ratio (RR) was estimated with the use of a random-effects model.

RESULTS

Nine RCTs (1150 patients) were included. RAAS blockade was associated with a significant reduction in progression to ESKD: RR 0.84 (95% confidence interval [CI] 0.74-0.96; P = 0.01). There was no benefit from RAAS blockade on all-cause mortality or MACE: RR 1.02 (95% CI 0.63-1.65; P = 0.93) and RR 0.87 (95% CI 0.49-1.57; P = 0.65), respectively.

CONCLUSIONS

RAAS blockade may be considered in selected patients with CKD stage 4-5 to delay progression to ESKD.

The significance of finerenone as a novel therapeutic option in diabetic kidney disease: a scoping review with emphasis on cardiorenal outcomes of the finerenone phase 3 trials

This scoping review prepared by endocrinology and nephrology experts aimed to address the significance of finerenone, as a novel therapeutic option, in diabetic kidney disease (DKD), based on the biological prospect of cardiorenal benefit due to non-steroidal mineralocorticoid receptor antagonist (MRA) properties, and the recent evidence from the finerenone phase 3 program clinical trials. The importance of finerenone in slowing DKD progression was critically reviewed in relation to the role of MR overactivation in the pathogenesis of cardiorenal disease and unmet needs in the current practice patterns. The efficacy and safety outcomes of finerenone phase III study program including FIDELIO-DKD, FIGARO-DKD and FIDELITY were presented. Specifically, perspectives on inclusion of patients with preserved estimated glomerular filtration rate (eGFR) or high albuminuria, concomitant use of sodium-glucose co-transporter-2 inhibitor (SGLT2i) or glucagon-like peptide 1 receptor agonist (GLP-1 RA), baseline glycated hemoglobin (HbA1c) level and insulin treatment, clinically meaningful heart failure outcomes and treatment-induced hyperkalemia were addressed. Finerenone has emerged as a new therapeutic agent that slows DKD progression, reduces albuminuria and risk of cardiovascular complications, regardless of the baseline HbA1c levels and concomitant treatments (SGLT2i, GLP-1 RA, or insulin) and with a favorable benefit-risk profile. The evolving data on the benefit of SGLT2is and non-steroidal MRAs in slowing or reducing cardiorenal risk seem to provide the opportunity to use these pillars of therapy in the management of DKD, after a long-period of treatment scarcity in this field. Along with recognition of the albuminuria as a powerful marker to detect those patients at high risk of cardiorenal disease, these important developments would likely to impact standard-of-care options in the setting of DKD.

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist 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 included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

Network pharmacology combined with Mendelian randomization analysis to identify the key targets of renin-angiotensin-aldosterone system inhibitors in the treatment of diabetic nephropathy

Background

Diabetic Nephropathy (DN) is one of the microvascular complications of diabetes. The potential targets of renin-angiotensin-aldosterone system (RAAS) inhibitors for the treatment of DN need to be explored.

Methods

The GSE96804 and GSE1009 datasets, 729 RAAS inhibitors-related targets and 6,039 DN-related genes were derived from the public database and overlapped with the differentially expressed genes (DN vs. normal) in GSE96804 to obtain the candidate targets. Next, key targets were screened via the Mendelian randomization analysis and expression analysis. The diagnostic nomogram was constructed and assessed in GSE96804. Additionally, enrichment analysis was conducted and a 'core active ingredient-key target-disease pathway' network was established. Finally, molecular docking was performed.

Results

In total, 60 candidate targets were derived, in which CTSC and PDE5A were screened as the key targets and had a causal association with DN as the protective factors (P < 0.05, OR < 1). Further, a nomogram exhibited pretty prediction efficiency. It is indicated that Benadryl hydrochloride might play a role in the DN by affecting the pathways of 'cytokine cytokine receptor interaction', etc. targeting the CTSC. Moreover, PDE5A might be involved in 'ECM receptor interaction', etc. for the effect of NSAID, captopril, chlordiazepoxide on DN. Molecular docking analysis showed a good binding ability of benadryl hydrochloride and CTSC, NSAID and PDE5A. PTGS2, ITGA4, and ANPEP are causally associated with acute kidney injury.

Conclusion

CTSC and PDE5A were identified as key targets for RAAS inhibitors in the treatment of DN, which might provide some clinical significance in helping to diagnose and treat DN. Among the targets of RAAS inhibitors, PTGS2, ITGA4 and ANPEP have a causal relationship with acute kidney injury, which is worthy of further clinical research.

Effect of preparation method for radioactive iodine therapy on serum electrolytes

PURPOSE

Thyroid hormone withdrawal (THW) in preparation for radioactive iodine therapy (RIT) may lead to hyponatremia and hyperkalemia because hypothyroidism reduces the glomerular filtration rate. Using recombinant human thyrotropin (rhTSH) may avoid these changes; however, these two preparation methods have not been compared in the literature. The purpose of this study was to reveal whether THW and rhTSH as preparation methods for RIT affect serum electrolytes differently. We also evaluated clinical factors influencing the onset of hyponatremia and hyperkalemia during RIT.

MATERIALS AND METHODS

From April 2005 to December 2020, we analyzed 278 patients with thyroid cancer who received RIT. The patients were classified into two groups based on the preparation method, and renal function and serum electrolytes were compared between the groups. We also evaluated clinical factors that may affect overt hyponatremia (serum sodium level < 134 mmol/L) and hyperkalemia (serum potassium level ≥ 5.0 mmol/L).

RESULTS

Serum sodium and chloride levels in the THW group were significantly lower than those in the rhTSH group (p < 0.001 and p = 0.002, respectively). In contrast, the serum potassium level in the THW group was significantly higher than that in the rhTSH group (p = 0.008). As for clinical factors that may influence hyponatremia, age and estimated glomerular filtration rate (eGFR) were significantly associated with serum sodium level in the univariate analysis (p = 0.033 and p = 0.006, respectively). In the multivariate analysis, only age was significantly associated with serum sodium level (p = 0.030). Regarding hyperkalemia, distant metastases, the preparation method and eGFR were significantly associated with the serum potassium level in the univariate analysis (p = 0.005, p = 0.005 and p = 0.001, respectively). In the multivariate analysis, only eGFR was significantly associated with hyperkalemia (p = 0.019).

CONCLUSION

THW and rhTSH affect serum sodium and potassium levels differently. Renal function may be risk factors for hyperkalemia, whereas older age may be a risk factor for hyponatremia.

Hyperkalemia in CKD: an overview of available therapeutic strategies

Hyperkalemia (HK) is a life-threatening condition that often occurs in patients with chronic kidney disease (CKD). High serum potassium (sKsK) is responsible for a higher risk of end-stage renal disease, arrhythmias and mortality. This risk increases in patients that discontinue cardio-nephroprotective renin-angiotensin-aldosterone system inhibitor (RAASi) therapy after developing HK. Hence, the management of HK deserves the attention of the clinician in order to optimize the therapeutic strategies of chronic treatment of HK in the CKD patient. The adoption in clinical practice of the new hypokalaemic agents patiromer and sodium zirconium cyclosilicate (SZC) for the prevention and chronic treatment of HK could allow patients, suffering from heart failure and chronic renal failure, to continue to benefit from RAASi therapy. We have updated a narrative review of the clear variables, correct definition, epidemiology, pathogenesis, etiology and classifications for HK among non-dialysis CKD (ND CKD) patients. Furthermore, by describing the prognostic impact on mortality and on the progression of renal damage, we want to outline the strategies currently available for the control of potassium (K+) plasma levels.

A randomized study to compare oral potassium binders in the treatment of acute hyperkalemia

BACKGROUND

The KBindER (K⁺ Binders in Emergency Room and hospitalized patients) clinical trial is the first head-to-head evaluation of oral potassium binders (cation-exchange resins) for acute hyperkalemia therapy.

METHODS

Emergency room and hospitalized patients with a blood potassium level ≥ 5.5 mEq/L are randomized to one of four study groups: potassium binder drug (sodium polystyrene sulfonate, patiromer, or sodium zirconium cyclosilicate) or nonspecific laxative (polyethylene glycol). Exclusion criteria include recent bowel surgery, ileus, diabetic ketoacidosis, or anticipated dialysis treatment within 4 h of treatment drug. Primary endpoints include change in potassium level at 2 and 4 h after treatment drug. Length of hospital stay, next-morning potassium level, gastrointestinal side effects and palatability will also be analyzed. We are aiming for a final cohort of 80 patients with complete data endpoints (20 per group) for comparative statistics including multivariate adjustment for kidney function, diabetes mellitus, congestive heart failure, metabolic acidosis, renin-angiotensin-aldosterone system inhibitor prescription, and treatment with other agents to lower potassium (insulin, albuterol, loop diuretics).

DISCUSSION

The findings from our study will inform decision-making guidelines on the role of oral potassium binders in the treatment of acute hyperkalemia.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04585542 . Registered 14 October 2020.

A systematic review and meta-analysis of the clinical impact of stopping renin-angiotensin system inhibitor in patients with chronic kidney disease

Although renin-angiotensin system (RAS) inhibitors reduce the risk of cardiovascular diseases and end-stage kidney disease (ESKD) in chronic kidney disease (CKD) patients, they are often discontinued in clinical practice due to drug-related adverse events. However, limited evidence is available about the clinical impact of RAS inhibitor discontinuation in CKD patients. A comprehensive search of publications investigating the effect of discontinuing RAS inhibitors on clinical outcomes in CKD patients in PubMed, the Cochrane Library, and Web of Science was conducted (inception to November 7, 2022), and potentially relevant studies were searched by hand (through November 30, 2022). Two reviewers independently extracted data according to the PRISMA and MOOSE guidelines and assessed the quality of each study with risk-of-bias tools, RoB2 and ROBINS-I. The pooled hazard ratio (HR) for each outcome was integrated with a random-effect model. A total of 1 randomized clinical trial and 6 observational studies involving 248,963 patients were included in the systematic review. The meta-analysis of observational studies showed that discontinuation of RAS inhibitors was associated with a higher risk of all-cause mortality (HR, 1.41 [95% CI, 1.23-1.62]; I² = 97%), ESKD (1.32 [95% CI, 1.10-1.57]; I² = 94%) and MACE (1.20 [95% CI 1.15-1.25]; I² = 38%), but not with hyperkalemia (0.79 [95% CI 0.55-1.15]; I² = 90%). Overall risk of bias was moderate-to-serious, and quality of evidence (GRADE system) was low-to-very low. The present study suggests that CKD patients would benefit from continuing RAS inhibitors.

The Nonsteroidal Mineralocorticoid-Receptor-Antagonist Finerenone in Cardiorenal Medicine: A State-of-the-Art Review of the Literature

Steroidal mineralocorticoid-receptor-antagonists (MRAs), such as spironolactone and eplerenone, are guideline-directed therapies in patients with heart failure with reduced ejection fraction or resistant hypertension. However, the associated risk of hyperkalemia and hormonal side effects limit their broad use and downstream cardiorenal protection in high-risk patients with type 2 diabetes mellitus (T2DM) and moderate-to-advanced chronic kidney disease (CKD). The critical unmet need to improve long-term cardiorenal outcomes in such patients with CKD has sparked considerable efforts to the discovery and development of a new class of compounds. Finerenone is a novel, nonsteroidal MRA that has recently received regulatory approval with the indication of cardiorenal protection in patients with CKD associated with T2DM. Two landmark phase 3 clinical trials, FIDELIO-DKD and FIGARO-DKD, demonstrated that among patients with T2DM and a broad spectrum of CKD, finerenone reduced the risk of "hard" cardiovascular and kidney failure outcomes as compared with placebo, with a minimal risk of hyperkalemia. Subgroup analyses of these trials also provided preliminary evidence that the efficacy and safety profile of finerenone was similar and irrespective of background therapy with other guideline-directed therapies, such as sodium-glucose co-transporter type 2 (SGLT-2) inhibitors and glucagone-like peptide 1 receptor agonists. Whether the combination of finerenone with a SGLT-2 inhibitor is more beneficial in patients with T2DM and CKD as compared with either therapy alone is a crucial research question that is currently under investigation in an ongoing clinical trial.

Renin-angiotensin-aldosterone pathway modulators in chronic kidney disease: A comparative review

Chronic kidney disease presents a health challenge that has a complex underlying pathophysiology, both acquired and inherited. The pharmacotherapeutic treatment options available today lower the progression of the disease and improve the quality of life but cannot completely cure it. This poses a challenge to the healthcare provider to choose, from the available options, the best way to manage the disease as per the presentation of the patient. As of now, the recommended first line of treatment to control the blood pressure in chronic kidney disease is the administration of renin-angiotensin-aldosterone system modulators. These are represented mainly by the direct renin inhibitor, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. These modulators are varied in their structure and mechanisms of action, hence showing varying treatment outcomes. The choice of administration of these modulators is determined by the presentation and the co-morbidities of the patient, the availability and affordability of the treatment option, and the expertise of the healthcare provider. A direct head-to-head comparison between these significant renin-angiotensin-aldosterone system modulators is lacking, which can benefit healthcare providers and researchers. In this review, a comparison has been drawn between the direct renin inhibitor (aliskiren), angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. This can be of significance for healthcare providers and researchers to find the particular loci of interest, either in structure or mechanism, and to intervene as per the case presentation to obtain the best possible treatment option.

Diabetic kidney disease in type 2 diabetes: a consensus statement from the Swiss Societies of Diabetes and Nephrology

Diabetic kidney disease is highly prevalent in patients with type 2 diabetes and is a major cause of end-stage renal disease in Switzerland. Patients with diabetic kidney disease are among the most complex patients in diabetes care. They require a multifactorial and multidisciplinary approach with the goal to slow the decline in glomerular filtration rate (GFR) and cardiovascular morbidity. With this consensus we propose an evidence-based guidance to health care providers involved in the care of type 2 diabetic patients with diabetic kidney disease.First, there is a need to increase physician awareness and improve screening for diabetic kidney disease as early intervention may improve clinical outcomes and the financial burden. Evaluation of estimated GFR (eGFR) and spot urine albumin/creatinine ratio is recommended at least annually. Once it is diagnosed, glucose control and optimisation of blood pressure control with renin-angiotensin system blockers have been recommended as mainstay management of diabetic kidney disease for more than 20 years. Recent, high quality randomised controlled trials have shown that sodium-glucose cotransporter-2 (SGLT2) inhibition slows eGFR decline and cardiovascular events beyond glucose control. Likewise, mineralocorticoid receptor antagonism with finerenone has cardiorenal protective effects in diabetic kidney disease. Glucagon-like peptide-1 (GLP1) receptor agonists improve weight loss if needed, and decrease albuminuria and cardiovascular morbidity. Lipid control is also important to decrease cardiovascular events. All these therapies are included in the treatment algorithms proposed in this consensus. With advancing kidney failure, other challenges may rise, such as hyperkalaemia, anaemia and metabolic acidosis, as well as chronic kidney disease-mineral and bone disorder. These different topics and treatment strategies are discussed in this consensus. Finally, an update on diabetes management in renal replacement therapy such as haemodialysis, peritoneal dialysis and renal transplantation is provided. With the recent developments of efficient therapies for diabetic kidney disease, it has become evident that a consensus document is necessary. We are optimistic that it will significantly contribute to a high-quality care for patients with diabetic kidney disease in Switzerland in the future.

Clinical outcomes following discontinuation of renin-angiotensin-system inhibitors in patients with type 2 diabetes and advanced chronic kidney disease: A prospective cohort study

Background

Renin-angiotensin-system inhibitors (RASi), that include angiotensin converting enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs) reduce proteinuria, delay chronic kidney disease (CKD) progression, protect against cardiovascular events and heart failure hospitalizations. We examined the associations of discontinuation of ACEi/ARBs with risk of clinical outcomes in Chinese patients with type 2 diabetes (T2D) and advanced-CKD (estimated-glomerular filtration rate [eGFR] <30 ml/min/1.73 m2).

Methods

We conducted a prospective, population-based cohort study including 10,400 patients with T2D in Hong Kong stratified by continuation of ACEi/ARBs within 6 months after reaching eGFR <30 ml/min/1.73 m2 from January 01, 2002 to December 31, 2018 and observed until December 31, 2019. The primary outcomes were death, major-adverse cardiovascular events (MACE), heart failure, end-stage kidney disease (ESKD), and all-cause mortality. Cox-model with time-dependent exposure and covariates was used to estimate the hazard ratio (HR) of outcomes in a propensity-score overlap-weighted cohort. The risk of occurrence of hyperkalemia (plasma potassium >5.5 mmol/L) in discontinued-ACEi/ARBs versus continued-ACEi/ARBs users was assessed in a register-based cohort.

Findings

In the population-based cohort of 10,400 ACEi/ARBs users with new-onset eGFR<30 ml/min/1.73 m2, 1766 (17.0%) discontinued ACEi/ARBs and 8634 (83.0%) persisted with treatment. During a median follow-up of 3.6 (interquartile range, IQR: 2.11-5.8) years (41,623 person-years), 13.5%, 12.9%, and 27.6% had incident MACE, heart failure and ESKD respectively, and 35.8% died. Discontinued-ACEi/ARBs use was associated with higher risk of MACE (HR = 1.27, 95% CI: 1.08-1.49), heart failure (HR = 1.85, 95% CI: 1.53-2.25) and ESKD (HR = 1.30, 95% CI: 1.17-1.43), and neutral risk of all-cause mortality (HR = 0.93, 95% CI: 0.86-1.01) compared to counterparts with continued use. In the register-based cohort (583 discontinued-ACEi/ARBs users and 3817 continued-ACEi/ARBs users), discontinued-ACEi/ARBs had neutral risk of hyperkalemia (HR = 0.95, 95% CI: 0.84-1.08).

Interpretation

Discontinuation of ACEi/ARBs was associated with increased risk of cardiovascular-renal events supporting their continued use in patients with T2D and advanced-CKD.

Funding

CUHK Impact Research Fellowship Scheme.

Can patiromer allow for intensified renin-angiotensin-aldosterone system blockade with losartan and spironolactone leading to decreased albuminuria in patients with chronic kidney disease, albuminuria and hyperkalaemia? An open-label randomised controlled trial: MorphCKD

INTRODUCTION

Chronic kidney disease (CKD) is associated with significantly increased morbidity and mortality. No specific treatment of the underlying condition is available for the majority of patients, but ACE-inhibitors (ACE-I) and angiotensin II-receptor blockers (ARB) slows progression in albuminuric CKD. Adding a mineralocorticoid receptor-antagonist (MRA) like spironolactone has an additive effect. However, renin-angiotensin-aldosterone system (RAAS)-blockade increases the risk of hyperkalaemia which is exacerbated by the presence of CKD. Thus, hyperkalaemia may prevent optimal use of RAAS-blockade in some patients.This project hypothesises that adding a potassium binder (patiromer) allows for improved RAAS-blockade including the use of MRA, thereby reducing albuminuria in patients with albuminuric CKD where full treatment is limited by hyperkalaemia.If successful, the study may lead to improved treatment of this subgroup of patients with CKD. Furthermore, the study will examine the feasibility of potassium binders in patients with CKD.

METHODS AND ANALYSIS

An open-label, randomised controlled trial including 140 patients with estimated glomerular filtration rate (eGFR) 25-60 mL/min/1.73 m², a urinary albumin/creatinine ratio (UACR) >500 mg/g (or 200 mg/g if diabetes mellitus) and a current or two previous plasma-potassium >4.5 mmol/L. Patients who develop hyperkaliaemia >5.5 mmol/L during a run-in phase, in which RAAS-blockade is intesified with the possible addition of spironolactone, are randomised to 12-month treatment with maximal tolerated ACE-I/ARB and spironolactone with or without patiromer.The primary endpoint is the difference in UACR measured at randomisation and 12 months compared between the two groups. Secondary endpoints include CKD progression, episodes of hyperkalaemia, blood pressure, eGFR, markers of cardiovascular disease, diet and quality of life.

ETHICS AND DISSEMINATION

This study is approved by The Central Denmark Region Committees on Health Research Ethics (REFNO 1-10-72-110-20) and is registered in the EudraCT database (REFNO 2020-001595-15). Results will be presented in peer-reviewed journals, at meetings and at international conferences.

Prevalence, recurrence and seasonal variation of hyperkalemia among patients on hemodialysis

PURPOSE

Observational studies have shown that among patients on hemodialysis, hyperkalemia is strongly associated with excess risk for cardiovascular-related hospitalizations and sudden cardiac death. However, the actual burden of hyperkalemia, the rates of its recurrence and seasonality in its variation still remain unclear.

METHODS

Between June 2020 and May 2021, 1786 mid-week pre-dialysis serum potassium (sK) measurements were retrospectively recorded from 149 patients receiving thrice-weekly hemodialysis in a single-center in Thessaloniki, Greece. The prevalence, recurrence and seasonal variation of hyperkalemia were assessed using three pre-specified sK thresholds (≥ 5.1, ≥ 5.5 and ≥ 6.0 mmol/L).

RESULTS

At baseline, 60.4%, 42.2% and 13.4% of patients had sK levels ≥ 5.1, ≥ 5.5 and ≥ 6.0 mmol/L, respectively. At any time-point during follow-up, 85.2%, 69.8% and 38.9% of patients experienced at least one hyperkalemic event ≥ 5.1, ≥ 5.5 and ≥ 6.0 mmol/L, respectively. Of the 104 patients experiencing an initial sK elevation ≥ 5.5 mmol/L, hyperkalemia at the same threshold reoccurred in 60.6% at month 1, in 47.1% at month 2 and in 46.1% at month 3 of follow-up. Seasonal variation was also observed, with the prevalence of hyperkalemia to be significantly higher in summer. Shorter delivered hemodialysis < 4 h/session (OR: 2.568; 95% CI 1.045-6.313) and the use of a high dialysate K concentration (OR: 14.646; 95% CI 2.727-78.647) were the 2 factors that were independently associated with hyperkalemia.

CONCLUSION

The present study shows that among hemodialysis patients, the rates of hyperkalemia prevalence and recurrence are very high, reflecting the large unmet need to identify more effective potassium-lowering therapeutic interventions in this high-risk population.

Evidence for Cardiorenal Protection with SGLT-2 Inhibitors and GLP-1 Receptor Agonists in Patients with Diabetic Kidney Disease

For almost two decades, the management of patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD) was based on the optimal glycemic and blood pressure control as well as on the adequate blockade of the renin-angiotensin-system. Over the past few years, sodium-glucose co-transporter 2 (SGLT-2) inhibitors and glucagone-like peptide 1 receptor agonists (GLP1-RAs) were added to our therapeutic armarhatum, offering promise for more effective mitigation of the substantial residual cardiorenal risk of these patients. Large randomized controlled trials (RCTs) designed to demonstrate the cardiovascular safety of SGLT-2 inhibitors and GLP1-RAs showed that these novel anti-diabetic medications improve cardiovascular outcomes in patients with T2DM. RCTs conducted specifically in CKD patients with or without T2DM demonstrated that SGLT-2 inhibitors were also effective in retarding the progression of kidney injury to end-stage kidney disease. The kidney protective effects of GLP1-RA are not yet proven, but RCTs are currently ongoing to investigate this crucial research question. In this article, we review the available clinical-trial evidence supporting the use of SGLT-2 inhibitors and GLP1-RAs for cardiorenal protection in patients with T2DM and CKD. We provide clinical practice recommendations for a personalized approach in the use of these novel therapies, according to the severity of CKD and the presence of other cardiometabolic risk factors.

Recent therapeutic targets in diabetic nephropathy

BACKGROUND

The prevalence of diabetes mellitus has been increased dramatically which in turn leads to complications including cardiovascular diseases, diabetic kidney disease, and substantially end-stage renal disease.

METHODS

We reviewed articles discussing the pathophysiology of diabetic nephropathy with new agents that may be useful in the management of the disease. We used PubMed, Scopus, Google Scholar and the Open-access searching engines.

RESULTS

The recent recommendations primarily depend on glycaemic and blood pressure control and the use of standard renin-angiotensin system blockade. Currently, the use of agents with nephroprotective effects beyond the hyperglycaemic lowering effect has been evidenced clinically.

CONCLUSIONS

In his review, the pathophysiology, clinical manifestations, and lines of treatment of diabetic nephropathy are discussed. In addition, a focus on the clinical role and nephroprotective effects of the emerging therapeutic class, dipeptidyl peptidase IV (DPP-4) inhibitors, is addressed in detail.

Novel therapeutic strategies for cardiorenal protection in patients with type 2 diabetes and chronic kidney disease

Type 2 diabetes mellitus (T2DM) is the leading cause of end-stage kidney disease (ESKD) worldwide [1]. The development of chronic kidney disease (CKD) in patients with T2DM substantially increases their risk for cardiovascular (CV) morbidity and mortality [2]. In fact, when T2DM and early-stage CKD co-exist, the risk for CV death is several times higher than the risk for progression to ESKD [3]. Therefore, there is a need for the development of novel therapies to improve CV and kidney failure outcomes in this high-risk population. In this brief perspective, we explore the role of sodium-glucose co-transporter type-2 (SGLT-2) inhibitors and the nonsteroidal mineralocorticoid-receptor-antagonist (MRA) finerenone, in the management of diabetic kidney disease (DKD).

Gitelman syndrome with a novel frameshift variant in SLC12A3 gene accompanied by chronic kidney disease and type 2 diabetes mellitus

Gitelman syndrome is an autosomal recessive genetic disease caused by pathogenic variants in SLC12A3 resulting in the loss of function of the Na-Cl co-transporter (NCC) in the distal tubules. Hypokalemia and diuretic effects can cause secondary type 2 diabetes and renal function decline. Here, we present the case of a 49-year-old male patient with chronic persistent treatment-resistant hypokalemia for the past 13 years who had been receiving treatment for type 2 diabetes mellitus for 6 years. He was referred to our department due to the presence of urinary protein, impaired renal function, high renin activity, and hyperaldosteronism. Laboratory test results showed hypokalemia, hypomagnesemia, hypocalciuria, and metabolic alkalosis. Using next-generation and Sanger sequencing, we identified a novel stop-gain variant (NM_000339.3:c.137del [p.His47fs]) and a missense variant (NM_000339.3:c.2927C > T [p.Ser976Phe]) in the SLC12A3 gene. This novel pathogenic variant was located at the intracellular N-terminus of the NCC. Based on these findings, the patient was diagnosed with Gitelman syndrome. The use of next-generation sequencing facilitated the exclusion of diseases with similar clinical symptoms.

Mineralocorticoid Receptor Antagonism in Chronic Kidney Disease

The overactivation of the mineralocorticoid receptor (MR) in animal models of chronic kidney disease (CKD) increases sodium retention and hypertension and provokes inflammation and fibrosis in the kidneys, blood vessels, and the heart; these processes play an important role in the progression of cardiorenal disease. Accordingly, blockade of the MR is an attractive therapeutic intervention to retard the progression of CKD and improve cardiovascular morbidity and mortality. Finerenone is a novel, nonsteroidal MR antagonist (MRA) with a unique mode of action that is distinct from currently available steroidal MRAs. In animal models of CKD, finerenone has a more favorable benefit/risk ratio as compared with the steroidal MRAs such as spironolactone and eplerenone. In patients with type 2 diabetes and heart and/or kidney disease, phase II trials have revealed that compared with spironolactone, eplerenone, or placebo, finerenone displays benefits that exceed the risks of MR antagonism. In patients with CKD and type 2 diabetes, a large phase III trial has shown that, compared with placebo, finerenone improved kidney failure and cardiovascular outcomes. In the first part of this article, we explore the safety and efficacy of spironolactone and eplerenone in early- and late-stage CKD. In the second part, we describe the mechanism of action of finerenone and discuss the promising role of this nonsteroidal MRA as a novel therapeutic opportunity to improve clinical outcomes in patients with CKD.

Chronic kidney disease

Chronic kidney disease is a progressive disease with no cure and high morbidity and mortality that occurs commonly in the general adult population, especially in people with diabetes and hypertension. Preservation of kidney function can improve outcomes and can be achieved through non-pharmacological strategies (eg, dietary and lifestyle adjustments) and chronic kidney disease-targeted and kidney disease-specific pharmacological interventions. A plant-dominant, low-protein, and low-salt diet might help to mitigate glomerular hyperfiltration and preserve renal function for longer, possibly while also leading to favourable alterations in acid-base homoeostasis and in the gut microbiome. Pharmacotherapies that alter intrarenal haemodynamics (eg, renin-angiotensin-aldosterone pathway modulators and SGLT2 [SLC5A2] inhibitors) can preserve kidney function by reducing intraglomerular pressure independently of blood pressure and glucose control, whereas other novel agents (eg, non-steroidal mineralocorticoid receptor antagonists) might protect the kidney through anti-inflammatory or antifibrotic mechanisms. Some glomerular and cystic kidney diseases might benefit from disease-specific therapies. Managing chronic kidney disease-associated cardiovascular risk, minimising the risk of infection, and preventing acute kidney injury are crucial interventions for these patients, given the high burden of complications, associated morbidity and mortality, and the role of non-conventional risk factors in chronic kidney disease. When renal replacement therapy becomes inevitable, an incremental transition to dialysis can be considered and has been proposed to possibly preserve residual kidney function longer. There are similarities and distinctions between kidney-preserving care and supportive care. Additional studies of dietary and pharmacological interventions and development of innovative strategies are necessary to ensure optimal kidney-preserving care and to achieve greater longevity and better health-related quality of life for these patients.

Hyperkalemia with RAAS inhibition: Mechanism, clinical significance, and management

Renin-angiotensin-aldosterone system (RAAS) inhibitors are evidence-based treatments for a number of conditions including hypertension, diabetes mellitus, chronic kidney disease, and congestive heart failure. Among the most common adverse effects of RAAS inhibitors is hyperkalemia which results from either reduced secretion of aldosterone or increased resistance to aldosterone. Many of the conditions for which RAAS inhibitors are recommended further amplify the risk for hyperkalemia in and of themselves. RAAS inhibitor-related hyperkalemia is associated with an increased risk for cardiovascular events, hospitalizations, and death. Yet discontinuation of RAAS inhibitors for patients with chronic kidney disease and congestive heart failure is also associated with an increased risk for cardiovascular events, hospitalizations, and death. Therefore, clinicians are often left to struggle with the dilemma of the best management approach to RAAS inhibitor-related hyperkalemia. The ideal solution involves pharmacotherapies that are safe and effective in mitigating hyperkalemia and allow patients to continue to receive the beneficial effects from RAAS inhibitors. In this regard, modern pharmacologic agents such as patiromer and zirconium cyclosilicate are providing a mechanism whereby physicians are better equipped to maintain their patients on RAAS inhibitors.

Risk of hyperkalemia from renin-angiotensin-aldosterone system inhibitors and factors associated with treatment discontinuities in a real-world population

BACKGROUND

Hyperkalemia rates in renin-angiotensin-aldosterone system (RAAS) inhibitor users, and factors associated with treatment interruptions and cessations, have not been explored in a large, population-wide database.

METHODS

RAAS inhibitor users were identified in the linked UK Clinical Practice Research Datalink-Hospital Episodes Statistics data set, 2009-15. Treatment interruptions (no active prescription followed by reappearance) and cessations were determined. Hyperkalemia (serum K+>5.5 mmol/L) rates were calculated and factors associated with interruptions and cessations modeled using time-varying Cox regression, including hyperkalemia (as a time-dependent variable).

RESULTS

Among 434 027 RAAS inhibitor users, the hyperkalemia rate was 1.30 (95% confidence interval 1.28-1.32) per 100 patient-years. Of 73.7% of patients who experienced off-treatment periods, 57.6% experienced interruption only, 7.5% cessation only and 8.6% both. Within 1 year of initiating RAAS inhibitor treatment, approximately one-third of the patients experienced interruption or cessation. Hazard ratios for patients with severe hyperkalemia were 1.10 (10.5-1.16) for interruptions and 3.37 (3.25-3.50) for cessation. Compared with no chronic kidney disease (CKD), risk of interruption was 1.20 (1.16-1.25) and 1.57 (1.44-1.72) for Stages 4 and 5, respectively, and of cessation was 2.20 (2.07-2.33) and 2.87 (2.56-3.22). Risk of interruption increased for patients with heart failure or diabetes [1.04 (1.02-1.05); 1.13 (1.12-1.14), respectively] but the risk of cessation decreased [0.85 (0.82-0.87); 0.92 (0.90-0.94)].

CONCLUSIONS

Risk of RAAS inhibitor interruption and cessation increased as CKD stage progressed. Efforts targeting reasons for interruptions and, especially, cessations, such as hyperkalemia prevention, could decrease off-treatment periods for patients who would otherwise benefit, such as those with CKD, heart failure or diabetes.

Sodium zirconium cyclosilicate for the management of chronic hyperkalemia in kidney disease, a novel agent

INTRODUCTION

Hyperkalemia is a common finding in patients with advanced kidney disease for multiple reasons. Renin-Angiotensin-Aldosterone-System Inhibitors (RAASi) that are indicated for slowing down progression of kidney disease are often associated with hyperkalemia which becomes a limiting factor in their use and titration to the maximum dose. Having a safe, effective, tolerable, and affordable potassium binder can help optimize RAAS inhibition in the setting of kidney disease.

AREAS COVERED

Although sodium polystyrene sulfonate has been a mainstay of acute management of hyperkalemia for decades, evidence regarding its efficacy is limited, and its chronic use is not routinely recommended for concerns regarding toxicity. The concern of gastrointestinal (GI) adverse effects with sodium polystyrene sulfonate has spurred the development of alternatives. Sodium zirconium cyclosilicate (SZC) is a promising agent that selectively binds potassium in the gut and eliminates it, while being safe for chronic use based on 1 year of data. Even though we do not have head-to-head studies among the three currently available binders, SZC stands out in rapidity of onset and efficacy.

EXPERT OPINION

In this review, we summarize the general management of hyperkalemia, including new agents. We review the pre-clinical and clinical data relating to sodium zirconium cyclosilicate.

Local cyclic adenosine monophosphate signalling cascades-Roles and targets in chronic kidney disease

The molecular mechanisms underlying chronic kidney disease (CKD) are poorly understood and treatment options are limited, a situation underpinning the need for elucidating the causative molecular mechanisms and for identifying innovative treatment options. It is emerging that cyclic 3',5'-adenosine monophosphate (cAMP) signalling occurs in defined cellular compartments within nanometre dimensions in processes whose dysregulation is associated with CKD. cAMP compartmentalization is tightly controlled by a specific set of proteins, including A-kinase anchoring proteins (AKAPs) and phosphodiesterases (PDEs). AKAPs such as AKAP18, AKAP220, AKAP-Lbc and STUB1, and PDE4 coordinate arginine-vasopressin (AVP)-induced water reabsorption by collecting duct principal cells. However, hyperactivation of the AVP system is associated with kidney damage and CKD. Podocyte injury involves aberrant AKAP signalling. cAMP signalling in immune cells can be local and slow the progression of inflammatory processes typical for CKD. A major risk factor of CKD is hypertension. cAMP directs the release of the blood pressure regulator, renin, from juxtaglomerular cells, and plays a role in Na⁺ reabsorption through ENaC, NKCC2 and NCC in the kidney. Mutations in the cAMP hydrolysing PDE3A that cause lowering of cAMP lead to hypertension. Another major risk factor of CKD is diabetes mellitus. AKAP18 and AKAP150 and several PDEs are involved in insulin release. Despite the increasing amount of data, an understanding of functions of compartmentalized cAMP signalling with relevance for CKD is fragmentary. Uncovering functions will improve the understanding of physiological processes and identification of disease-relevant aberrations may guide towards new therapeutic concepts for the treatment of CKD.

Mineralcorticoid receptor blockers in chronic kidney disease

There are many experimental data supporting the involvement of aldosterone and mineralcorticoid receptor (MR) activation in the genesis and progression of chronic kidney disease (CKD) and cardiovascular damage. Many studies have shown that in diabetic and non-diabetic CKD, blocking the renin-angiotensin-aldosterone (RAAS) system with conversion enzyme inhibitors (ACEi) or angiotensin II receptor blockers (ARBs) decreases proteinuria, progression of CKD and mortality, but there is still a significant residual risk of developing these events. In subjects treated with ACEi or ARBs there may be an aldosterone breakthrough whose prevalence in subjects with CKD can reach 50%. Several studies have shown that in CKD, the aldosterone antagonists (spironolactone, eplerenone) added to ACEi or ARBs, reduce proteinuria, but increase the risk of hyperkalemia. Other studies in subjects treated with dialysis suggest a possible beneficial effect of antialdosteronic drugs on CV events and mortality. Newer potassium binders drugs can prevent/decrease hyperkalemia induced by RAAS blockade, and may reduce the high discontinuation rates or dose reduction of RAAS-blockers. The nonsteroidal MR blockers, with more potency and selectivity than the classic ones, reduce proteinuria and have a lower risk of hyperkalemia. Several clinical trials, currently underway, will determine the effect of classic MR blockers on CV events and mortality in subjects with stage 3b CKD and in dialysis patients, and whether in patients with type 2 diabetes mellitus and CKD, optimally treated and with high risk of CV and kidney events, the addition of finerenone to their treatment produces cardiorenal benefits. Large randomized trials have shown that sodium glucose type 2 cotransporter inhibitors (SGLT2i) reduce mortality and the development and progression of diabetic and nondiabetic CKD. There are pathophysiological arguments, which raise the possibility that the triple combination ACEi or ARBs, SGLT2i and aldosterone antagonist provide additional renal and cardiovascular protection.

Clinical Management of Hyperkalemia

Hyperkalemia is an electrolyte abnormality with potentially life-threatening consequences. Despite various guidelines, no universally accepted consensus exists on best practices for hyperkalemia monitoring, with variations in precise potassium (K⁺) concentration thresholds or for the management of acute or chronic hyperkalemia. Based on the available evidence, this review identifies several critical issues and unmet needs with regard to the management of hyperkalemia. Real-world studies are needed for a better understanding of the prevalence of hyperkalemia outside the clinical trial setting. There is a need to improve effective management of hyperkalemia, including classification and K⁺ monitoring, when to reinitiate previously discontinued renin-angiotensin-aldosterone system inhibitor (RAASi) therapy, and when to use oral K⁺-binding agents. Monitoring serum K⁺ should be individualized; however, increased frequency of monitoring should be considered for patients with chronic kidney disease, diabetes, heart failure, or a history of hyperkalemia and for those receiving RAASi therapy. Recent clinical studies suggest that the newer K⁺ binders (patiromer sorbitex calcium and sodium zirconium cyclosilicate) may facilitate optimization of RAASi therapy. Enhancing the knowledge of primary care physicians and internists with respect to the safety profiles of these newer K⁺ binders may increase confidence in managing patients with hyperkalemia. Lastly, the availability of newer K⁺-binding agents requires further study to establish whether stringent dietary K⁺ restrictions are needed in patients receiving K⁺-binder therapy. Individualized monitoring of serum K⁺ among patients with an increased risk of hyperkalemia and the use of newer K⁺-binding agents may allow for optimization of RAASi therapy and more effective management of hyperkalemia.

DPP4 inhibition mitigates ANG II-mediated kidney immune activation and injury in male mice

Recent evidence suggests that dipeptidyl peptidase-4 (DPP4) inhibition with saxagliptin (Saxa) is renoprotective under comorbid conditions associated with activation of the renin-angiotensin-aldosterone system (RAAS), such as diabetes, obesity, and hypertension, which confer a high cardiovascular risk. Immune system activation is now recognized as a contributor to RAAS-mediated tissue injury, and, importantly, immunomodulatory effects of DPP4 have been reported. Accordingly, we examined the hypothesis that DPP4 inhibition with Saxa attenuates angiotensin II (ANG II)-induced kidney injury and albuminuria via attenuation of immune activation in the kidney. To this end, male mice were infused with either vehicle or ANG II (1,000 ng/kg/min, s.c.) for 3 wk and received either placebo or Saxa (10 mg/kg/day, p.o.) during the final 2 wk. ANG II infusion increased kidney, but not plasma, DPP4 activity in vivo as well as DPP4 activity in cultured proximal tubule cells. The latter was prevented by angiotensin receptor blockade with olmesartan. Further, ANG II induced hypertension and kidney injury characterized by mesangial expansion, mitochondrial damage, reduced brush border megalin expression, and albuminuria. Saxa inhibited DPP4 activity ∼50% in vivo and attenuated ANG II-mediated kidney injury, independent of blood pressure. Further mechanistic experiments revealed mitigation by Saxa of proinflammatory and profibrotic mediators activated by ANG II in the kidney, including CD8⁺ T cells, resident macrophages (CD11b^hiF4/80^loLy6C^-), and neutrophils. In addition, Saxa improved ANG II suppressed anti-inflammatory regulatory T cell and T helper 2 lymphocyte activity. Taken together, these results demonstrate, for the first time, blood pressure-independent involvement of renal DPP4 activation contributing to RAAS-dependent kidney injury and immune activation.NEW & NOTEWORTHY This work highlights the role of dipeptidyl peptidase-4 (DPP4) in promoting ANG II-mediated kidney inflammation and injury. Specifically, ANG II infusion in mice led to increases in blood pressure and kidney DPP4 activity, which then led to activation of CD8⁺ T cells, Ly6C^- macrophages, and neutrophils and suppression of anti-inflammatory T helper 2 lymphocytes and regulatory T cells. Collectively, this led to kidney injury, characterized by mesangial expansion, mitochondrial damage, and albuminuria, which were mitigated by DPP4 inhibition independent of blood pressure reduction.

[Mineralcorticoid receptor blockers in chronic kidney disease]

There are many experimental data supporting the involvement of aldosterone and mineralcorticoid receptor (MR) activation in the genesis and progression of chronic kidney disease (CKD) and cardiovascular damage. Many studies have shown that in diabetic and non-diabetic CKD, blocking the renin- angiotensin-aldosterone (RAAS) system with conversion enzyme inhibitors (ACEi) or angiotensin II receptor blockers (ARBs) decreases proteinuria, progression of CKD and mortality, but there is still a significant residual risk of developing these events. In subjects treated with ACEi or ARBs there may be an aldosterone breakthrough whose prevalence in subjects with CKD can reach 50%. Several studies have shown that in CKD, the aldosterone antagonists (spironolactone, eplerenone) added to ACEi or ARBs, reduce proteinuria, but increase the risk of hyperkalemia. Other studies in subjects treated with dialysis suggest a possible beneficial effect of antialdosteronic drugs on CV events and mortality. Newer potassium binders drugs can prevent / decrease hyperkalemia induced by RAAS blockade, and may reduce the high discontinuation rates or dose reduction of RAAS-blockers. The nonsteroidal MR blockers, with more potency and selectivity than the classic ones, reduce proteinuria and have a lower risk of hyperkalemia. Several clinical trials, currently underway, will determine the effect of classic MR blockers on CV events and mortality in subjects with stage 3b CKD and in dialysis patients, and whether in patients with type 2 diabetes mellitus and CKD, optimally treated and with high risk of CV and kidney events, the addition of finerenone to their treatment produces cardiorenal benefits. Large randomized trials have shown that sodium glucose type 2 cotransporter inhibitors (SGLT2i) reduce mortality and the development and progression of diabetic and nondiabetic CKD. There are pathophysiological arguments, which raise the possibility that the triple combination ACEi or ARBs, SGLT2i and aldosterone antagonist provide additional renal and cardiovascular protection.

Poricoic acid A as a modulator of TPH-1 expression inhibits renal fibrosis via modulating protein stability of β-catenin and β-catenin-mediated transcription

BACKGROUND

Renal fibrosis is the common feature of chronic kidney disease (CKD). However, few drugs specifically target fibrogenesis due to the lack of an effective therapeutic target. Hence, it is urgent to find a therapeutic strategy that inhibits renal fibrosis. Here, we identified that poricoic acid A (PAA) as the modulator of tryptophan hydroxylase-1 (TPH-1), the key enzyme in tryptophan metabolism, exerted potent anti-fibrotic effects in the kidney.

METHODS

Lentiviral vector, luciferase reporter activity assay and co-immunoprecipitation were used. The animal model of unilateral ureteral obstruction and adenine-induced chronic renal failure as well as transforming growth factor (TGF)-β1-treated epithelial cells NRK-52E and fibroblasts NRK-49F were used.

RESULTS

TPH-1 was gradually decreased during CKD progression, while PAA treatment significantly increased TPH-1 expression to suppress renal fibrosis. Pharmacological overexpression of TPH-1 by PAA treatment exhibited anti-fibrosis and was linked to Wnt/β-catenin signaling activity. TPH-1 exhibited anti-fibrotic effects by suppressing epithelial cell injury and fibroblast activation, and PAA promoted TPH-1 expression and then suppressed the Wnt/β-catenin signaling pathway via regulating the protein stability of β-catenin and β-catenin-mediated transcription. TPH-1 overexpression enhanced the anti-fibrotic effects of PAA, while TPH-1 deficiency weakened the anti-fibrotic effects of PAA, indicating that TPH-1 was required for the anti-fibrotic effects of PAA.

CONCLUSION

PAA as a modulator of TPH-1 expression attenuated renal fibrosis through regulating the Wnt/β-catenin signaling pathway by acting on the protein stability of β-catenin and β-catenin-mediated transcription. TPH-1 was required for PAA to exert anti-fibrosis.

Resistant Hypertension in Chronic Kidney Disease (CKD): Prevalence, Treatment Particularities, and Research Agenda

PURPOSE OF REVIEW

To explore the prevalence, treatment particularities, and research agenda in the management of resistant hypertension among patients with chronic kidney disease (CKD).

RECENT FINDINGS

The prevalence of resistant hypertension is reported to be 2-3 times higher in patients with CKD than in the general hypertensive population. Based in part on the results of the PATHWAY-2 trial showing add-on spironolactone to be superior to placebo or active treatment with an α- or β-blocker in reducing BP, international guidelines recommend the use of spironolactone as fourth-line agent in pharmacotherapy of resistant hypertension. Despite the several-fold higher burden of resistant hypertension among patients with stage 3b-4 CKD, the use of spironolactone in this population has been restricted, mainly due to the risk of hyperkalemia. The recently reported AMBER trial showed that among patients with uncontrolled resistant hypertension and an estimated glomerular filtration rate of 25-45 ml/min/1.73m², the newer potassium-binder patiromer prevented the development of hyperkalemia and increased the proportion of participants who remained on add-on spironolactone over 12 weeks of follow-up. Administration of spironolactone was associated with a clinically meaningful reduction of 11-12 mmHg in unattended automated office systolic blood pressure (BP) over the course of the AMBER trial. Newer potassium-binding therapies overcome the barrier of hyperkalemia and facilitate the persistent use of spironolactone, which is an effective add-on therapy to control BP in patients with resistant hypertension and advanced CKD. Future trials are now warranted to explore whether this strategy confers benefits on "hard" clinical outcomes in this high-risk population.

The role of patiromer: Comparing OPAL-HK data with untreated real-world patients in the United Kingdom-A retrospective, propensity-matched analysis

OBJECTIVES

The first phase of the published OPAL-HK study was a single-group treatment phase, which showed that patiromer normalised serum potassium at 4weeks in patients with chronic kidney disease stages 3-4 who were receiving renin-angiotensin-aldosterone inhibitors. We utilised real-world data to provide a control comparison to evaluate patiromer's efficacy in lowering serum potassium.

MATERIALS AND METHODS

The Salford Kidney Study (SKS) in the United Kingdom provided a matched cohort. After applying OPAL-HK inclusion and exclusion criteria, patients with an outpatient potassium level between 5.1mmol/L to <6.5mmol/L and whose next outpatient level was checked 24-42 days later were selected. Patients underwent 1:1 matching with the 243 OPAL-HK patients using propensity matching based on 6 variables: age, gender, estimated glomerular filtration rate, diabetes, heart failure and potassium level. The study outcomes aligned with the OPAL-HK treatment phase: mean change in baseline potassium, and the proportion of patients with a potassium of 3.8 to <5.1mmol/L at follow-up.

RESULTS

The study comprised 87 precisely matched patients. The mean follow-up in the 87 SKS patients was 31±5 days. At baseline, matched patients had a mean potassium of 5.5±0.3mmol/L. At follow-up, the mean level was unchanged in SKS patients but was 4.5±0.5mmol/L in the OPAL-HK group (p<0.001), a mean (±SE) change of -1.00±0.06mmol/L. The target range of 3.8 to <5.1mmol/L was reached in 80% of OPAL-HK patients compared with 0% in the SKS cohort. There were very few interventions undertaken to reduce hyperkalaemia in SKS patients.

CONCLUSIONS

Using real-world data as a matched control arm for the first phase of the OPAL-HK study, we highlight a potential role for patiromer in lowering potassium levels in patients with CKD 3-4 receiving renin-angiotensin-aldosterone inhibitors.

Common Drug Pipelines for the Treatment of Diabetic Nephropathy and Hepatopathy: Can We Kill Two Birds with One Stone?

Type 2 diabetes (T2D) is associated with diabetic nephropathy as well as nonalcoholic steatohepatitis (NASH), which can be called "diabetic hepatopathy or diabetic liver disease". NASH, a severe form of nonalcoholic fatty disease (NAFLD), can sometimes progress to cirrhosis, hepatocellular carcinoma and hepatic failure. T2D patients are at higher risk for liver-related mortality compared with the nondiabetic population. NAFLD is closely associated with chronic kidney disease (CKD) or diabetic nephropathy according to cross-sectional and longitudinal studies. Simultaneous kidney liver transplantation (SKLT) is dramatically increasing in the United States, because NASH-related cirrhosis often complicates end-stage renal disease. Growing evidence suggests that NAFLD and CKD share common pathogenetic mechanisms and potential therapeutic targets. Glucagon-like peptide 1 (GLP-1) receptor agonists and sodium-glucose cotransporter 2 (SGLT2) inhibitors are expected to ameliorate NASH and diabetic nephropathy/CKD. There are no approved therapies for NASH, but a variety of drug pipelines are now under development. Several agents of them can also ameliorate diabetic nephropathy/CKD, including peroxisome proliferator-activated receptors agonists, apoptosis signaling kinase 1 inhibitor, nuclear factor-erythroid-2-related factor 2 activator, C-C chemokine receptor types 2/5 antagonist and nonsteroidal mineral corticoid receptor antagonist. This review focuses on common drug pipelines in the treatment of diabetic nephropathy and hepatopathy.

Regulation of autophagy in leukocytes through RNA N6-adenosine methylation in chronic kidney disease patients

Patients with chronic kidney diseases have multiple cellular dysfunctions leading to increased atherosclerosis, impaired immunity, and disturbed metabolism. However, it is unclear what is the fundamental signaling served as a marker or as a mediator for the dysregulated function in their leukocytes or tissues. Here we hypothesized that the N⁶-Methyladenosine (m⁶A) modification of the RNA in the leukocytes is responsible for the cellular dysfunction in chronic kidney diseases. Patients with chronic kidney diseases had significantly less m⁶A abundances in leukocytes and elevated RNA demethylase FTO proteins. The uremic toxin, indoxyl sulfate, activated the autophagy flux through modulation of FTO and m⁶A modifications in RNA. Notably, knockdown of FTO or inhibit the m⁶A by 3-deazaadenosine blocks the effects of indoxyl sulfate on autophagy activation in cells. These findings provide new insights into the mechanisms underlying chronic kidney disease-associated cellular dysfunction. Targeting RNA m⁶A modification may be a novel strategy for the treatment of chronic kidney diseases and autophagy.

Potassium Binders for Hyperkalemia in Chronic Kidney Disease-Diet, Renin-Angiotensin-Aldosterone System Inhibitor Therapy, and Hemodialysis

Hyperkalemia is a potentially life-threatening complication of chronic kidney disease (CKD). The management of CKD requires balancing the benefits of specific treatments, which may exacerbate the potential for hyperkalemia, with the risks of hyperkalemia itself. Renin-angiotensin-aldosterone system (RAAS) inhibitors, which slow CKD progression and improve cardiovascular outcomes, are often discontinued if hyperkalemia develops. Patients with hyperkalemia are frequently advised to restrict dietary potassium (K⁺), depriving these patients of many heart-healthy foods. Patients receiving hemodialysis are particularly susceptible to hyperkalemia during long interdialytic intervals, and managing this risk without causing hypokalemia can be challenging. Recently, 2 K⁺-binding agents were approved for the treatment of hyperkalemia: sodium zirconium cyclosilicate and patiromer. These agents offer alternatives to sodium polystyrene sulfonate, which is associated with serious gastrointestinal adverse effects. For this review, PubMed was searched for English-language articles published in 2014-2018 using the terms patiromer, sodium zirconium cyclosilicate, sodium polystyrene sulfonate, hyperkalemia, renin-angiotensin-aldosterone, diet, and dialysis. In randomized controlled studies of patients with hyperkalemia, sodium zirconium cyclosilicate and patiromer effectively reduced serum K⁺ and were generally well tolerated. Furthermore, patients in these studies could maintain RAAS inhibitor therapy and, in some studies, were not required to limit dietary K⁺. There may also be a role for these agents in preventing hyperkalemia in patients receiving hemodialysis. Thus, K⁺-binding agents may allow patients with CKD at risk for hyperkalemia to optimize RAAS inhibitor therapy, receive benefits of a K⁺-rich diet, and experience improved hemodialysis outcomes. Additional long-term studies are necessary to confirm these effects.

Efficacy and safety of sodium zirconium cyclosilicate for hyperkalaemia: the randomized, placebo-controlled HARMONIZE-Global study

Aims

Sodium zirconium cyclosilicate (SZC, formerly ZS‐9) is a selective K⁺ binder to treat adults with hyperkalaemia. HARMONIZE‐Global examined the efficacy and safety of SZC among outpatients with hyperkalaemia from diverse geographic and ethnic origins.

Methods and results

This phase 3, randomized, double‐blind, placebo‐controlled study recruited outpatients with serum K⁺ ≥5.1 mmol/L (measured by point‐of‐care i‐STAT device) at 45 sites in Japan, Russia, South Korea, and Taiwan. Following open‐label treatment with thrice‐daily SZC 10 g during a 48 h correction phase (CP), patients achieving normokalaemia (K⁺ 3.5–5.0 mmol/L) were randomized 2:2:1 to once‐daily SZC 5 g, SZC 10 g, or placebo during a 28 day maintenance phase (MP). The primary endpoint was mean central‐laboratory K⁺ level during days 8–29 of the MP. Of 267 patients in the CP, 248 (92.9%) entered the MP. During the CP, mean central‐laboratory K⁺ was reduced by 1.28 mmol/L at 48 h vs. baseline (P < 0.001). During the MP (days 8–29), SZC 5 and 10 g once‐daily significantly lowered mean central‐laboratory K⁺ by 9.6% and 17.7%, respectively, vs. placebo (P < 0.001 for both). More patients had normokalaemia (central‐laboratory K⁺ 3.5–5.0 mmol/L at day 29) with SZC 5 (58.6%) and 10 g (77.3%) vs. placebo (24.0%), with the greatest number of normokalaemic days in the 10‐g group. The most common adverse events with SZC were mild or moderate constipation and oedema.

Conclusions

Normokalaemia achieved during the CP was maintained over 28 days with SZC treatment among outpatients with hyperkalaemia.

Hyperkalemia in chronic kidney disease

Hyperkalemia is a frequent finding in patients with chronic kidney disease (CKD). This increase in serum potassium levels is associated with decreased renal ion excretion, as well as the use of medications to reduce the progression of CKD or to control associated diseases such as diabetes mellitus and heart failure. Hyperkalemia increases the risk of cardiac arrhythmia episodes and sudden death. Thus, the control of potassium elevation is essential for reducing the mortality rate in this population. Initially, the management of hyperkalemia includes orientation of low potassium diets and monitoring of patients' adherence to this procedure. It is also important to know the medications in use and the presence of comorbidities to guide dose reduction or even temporary withdrawal of any of the potassium retention-related drugs. And finally, the use of potassium binders is indicated in both acute episodes and chronic hyperkalemia.