Endothelin and endothelin antagonists in chronic kidney disease

Therapeutic approaches for pulmonary hypertension in patients with chronic kidney disease

PURPOSE OF REVIEW

Pulmonary hypertension is a common comorbidity in patients with chronic kidney disease (CKD), but therapeutic options are limited. We discuss the epidemiology of pulmonary hypertension in patients with CKD and review therapies for pulmonary hypertension with a focus on emerging treatments for pulmonary arterial hypertension (PAH).

RECENT FINDINGS

The definition of pulmonary hypertension has been updated to a lower threshold of mean pulmonary artery pressures of more than 20 mmHg, potentially leading to more patients with CKD to qualify for the diagnosis of pulmonary hypertension. Endothelin receptor antagonists, a class of medications, which demonstrated efficacy in patients with PAH, have been shown to slow progression of CKD, but their efficacy in lowering pulmonary artery pressures and their effects on reducing cardiovascular mortality in this population remains unproven. Sotatercept, a novel activin signaling inhibitor, which was previously studied in dialysis patients has been shown to increase exercise capacity in patients with PAH. These studies may lead to new specific therapies for pulmonary hypertension in patients with CKD.

SUMMARY

Pulmonary hypertension is common in patients with CKD. Although our understanding of factors leading to pulmonary hypertension in this population have evolved, evidence supporting disease-specific therapy in CKD is limited arguing for larger, long-term studies.

Drug repurposing for glomerular diseases: an underutilized resource

Drug repurposing in glomerular disease can deliver opportunities for steroid-free regimens, enable personalized multi-target options for resistant or relapsing disease and enhance treatment options for understudied populations (for example, children) and in resource-limited settings. Identification of drug-repurposing candidates can be data driven, which utilizes existing data on disease pathobiology, drug features and clinical outcomes, or experimental, which involves high-throughput drug screens. Information from databases of approved drugs, clinical trials and PubMed registries suggests that at least 96 drugs on the market cover 49 targets with immunosuppressive potential that could be candidates for drug repurposing in glomerular disease. Furthermore, evidence to support drug repurposing is available for 191 immune drug target-glomerular disease pairs. Non-immunological drug repurposing includes strategies to reduce haemodynamic overload, podocyte injury and kidney fibrosis. Recommended strategies to expand drug-repurposing capacity in glomerular disease include enriching drug databases with glomeruli-specific information, enhancing the accessibility of primary clinical trial data, biomarker discovery to improve participant selection into clinical trials and improve surrogate outcomes and initiatives to reduce patent, regulatory and organizational hurdles.

A new perspective on proteinuria and drug therapy for diabetic kidney disease

Diabetic kidney disease (DKD) is one of the leading causes of end-stage renal disease worldwide and significantly increases the risk of premature death due to cardiovascular diseases. Elevated urinary albumin levels are an important clinical feature of DKD. Effective control of albuminuria not only delays glomerular filtration rate decline but also markedly reduces cardiovascular disease risk and all-cause mortality. New drugs for treating DKD proteinuria, including sodium-glucose cotransporter two inhibitors, mineralocorticoid receptor antagonists, and endothelin receptor antagonists, have shown significant efficacy. Auxiliary treatment with proprietary Chinese medicine has also yielded promising results; however, it also faces a broader scope for development. The mechanisms by which these drugs treat albuminuria in patients with DKD should be described more thoroughly. The positive effects of combination therapy with two or more drugs in reducing albuminuria and protecting the kidneys warrant further investigation. Therefore, this review explores the pathophysiological mechanism of albuminuria in patients with DKD, the value of clinical diagnosis and prognosis, new progress and mechanisms of treatment, and multidrug therapy in patients who have type 2 diabetic kidney disease, providing a new perspective on the clinical diagnosis and treatment of DKD.

Weibel-Palade bodies: function and role in thrombotic thrombocytopenic purpura and in diarrhea phase of STEC-hemolytic uremic syndrome

Vascular endothelial cells are equipped with numerous specialized granules called Weibel-Palade bodies (WPBs). They contain a cocktail of proteins that can be rapidly secreted (3-5 min) into the vascular lumen after an appropriate stimulus such as thrombin. These proteins are ready without synthesis. Von Willebrand factor (VWF) and P-selectin are the main constituents of WPBs. Upon stimulation, release of ultralarge VWF multimers occurs and assembles into VWF strings on the apical side of endothelium. The VWF A1 domain becomes exposed in a shear-dependent manner recruiting and activating platelets. VWF is able to recruit leukocytes via direct leukocyte binding or via the activated platelets promoting NETosis. Ultralarge VWF strings are ultimately cleaved into smaller pieces by the protease ADAMTS-13 preventing excessive platelet adhesion. Under carefully performed flowing conditions and adequate dose of Shiga toxins, the toxin induces the release of ultralarge VWF multimers from cultured endothelial cells. This basic information allows insight into the pathogenesis of thrombotic thrombocytopenic purpura (TTP) and of STEC-HUS in the diarrhea phase. In TTP, ADAMTS-13 activity is deficient and systemic aggregation of platelets will occur after a second trigger. In STEC-HUS, stimulated release of WPB components in the diarrhea phase of the disease can be presumed to be the first hit in the damage of Gb3 positive endothelial cells.

Mechanism of protective actions of sparsentan in the kidney: lessons from studies in models of chronic kidney disease

Simultaneous inhibition of angiotensin II AT1 and endothelin ETA receptors has emerged as a promising approach for treatment of chronic progressive kidney disease. This therapeutic approach has been advanced by the introduction of sparsentan, the first dual AT1 and ETA receptor antagonist. Sparsentan is a single molecule with high affinity for both receptors. It is US Food and Drug Administration approved for immunoglobulin A nephropathy (IgAN) and is currently being developed as a treatment for rare kidney diseases, such as focal segmental glomerulosclerosis. Clinical studies have demonstrated the efficacy and safety of sparsentan in these conditions. In parallel with clinical development, studies have been conducted to elucidate the mechanisms of action of sparsentan and its position in the context of published evidence characterizing the nephroprotective effects of dual ETA and AT1 receptor inhibition. This review summarizes this evidence, documenting beneficial anti-inflammatory, antifibrotic, and hemodynamic actions of sparsentan in the kidney and protective actions in glomerular endothelial cells, mesangial cells, the tubulointerstitium, and podocytes, thus providing the rationale for the use of sparsentan as therapy for focal segmental glomerulosclerosis and IgAN and suggesting potential benefits in other renal diseases, such as Alport syndrome.

Is endothelin targeting finally ready for prime time?

The endothelin family of peptides has long been recognized as a physiological regulator of diverse biological functions and mechanistically involved in various disease states, encompassing, among others, the cardiovascular system, the kidney, and the nervous system. Pharmacological blockade of the endothelin system, however, has encountered strong obstacles in its entry into the clinical mainstream, having obtained only a few proven indications until recently. This translational gap has been attributable predominantly to the relevant side effects associated with endothelin receptor antagonism (ERA), particularly fluid retention. Of recent, however, an expanding understanding of the pathophysiological processes involving endothelin, in conjunction with the development of new antagonists of endothelin receptors or adjustment of their doses, has driven a flourish of new clinical trials. The favorable results of some of them have extended the proven indications for ET targeting to a variety of clinical conditions, including resistant arterial hypertension and glomerulopathies. In addition, on the ground of strong preclinical evidence, other studies are ongoing to test the potential benefits of ERA in combination with other treatments, such as sodium-glucose co-transporter 2 inhibition in fluid retentive states or anti-cancer therapies in solid tumors. Furthermore, antibodies providing long-term blockade of endothelin receptors are under testing to overcome the short half-life of most small molecule endothelin antagonists. These efforts may yet bring new life to the translation of endothelin targeting strategies in clinical practice.

Sparsentan: A First-in-Class Dual Endothelin and Angiotensin II Receptor Antagonist

OBJECTIVE

To provide an overview of the guidelines on the management of immunoglobulin A nephropathy (IgAN) and focal segmental glomerulosclerosis (FSGS), review the evidence for sparsentan, and discuss its place in therapy.

DATA SOURCES

A literature search was conducted using MEDLINE, EMBASE, and clinicaltrials.gov using the search terms "sparsentan" and "RE-021" up to the end of Jun 2023.

STUDY SELECTION AND DATA EXTRACTION

English studies were included if they evaluated the pharmacology, pharmacokinetics, efficacy, and safety of sparsentan in human subjects. Information from the Food and Drug Administration (FDA) and manufacturer's monograph were also extracted.

DATA SYNTHESIS

In comparison with irbesartan, sparsentan reduced urine protein-to-creatinine ratio (UPCR) in both IgAN (-49.8% vs -15.1% at interim 36 weeks) and FSGS (-44.8% vs -18.5% at 8 weeks). Hypotension and edema were the most common adverse events in the sparsentan groups. Hepatotoxicity appears to be comparable between sparsentan and irbesartan in short-term results.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE IN COMPARISON WITH EXISTING DRUGS

Sparsentan provides a new option for patients with IgAN who are otherwise at high risk of progressive kidney disease. Continued FDA approval is dependent on long-term study results on renal function decline and safety.

CONCLUSION

Sparsentan reduces proteinuria in IgAN and FSGS, and has expedited approval by the FDA for IgAN in patients at risk of rapid disease progression, generally at urine protein-to-creatinine ratio (UPCR) ≥1.5 g/g. Interim results from PROTECT and results from DUET showed promise for improving proteinuria in IgAN and FSGS. Long-term renal function benefit and safety data are pending.

Sparsentan for Focal Segmental Glomerulosclerosis in the DUET Open-Label Extension: Long-term Efficacy and Safety

Rationale & Objective

Sparsentan is a novel, non-immunosuppressive, single-molecule, dual endothelin angiotensin receptor antagonist (DEARA) examined in the ongoing phase 2 DUET trial for focal segmental glomerulosclerosis (FSGS). In the DUET 8-week double-blind period, sparsentan resulted in greater proteinuria reduction versus irbesartan. We report the long-term efficacy and safety of sparsentan during the open-label extension over more than 4 years.

Study Design

Patients were examined from their first sparsentan dose (double-blind period or open-label extension) through 4.6 years.

Setting & Participants

Patients with FSGS, excluding secondary FSGS.

Intervention

Sparsentan (200, 400, and 800 mg/d).

Outcomes

Urinary protein-creatinine ratio, FSGS partial remission endpoint (urinary protein-creatinine ratio ≤1.5 g/g and >40% reduction from baseline), estimated glomerular filtration rate, and blood pressure approximately every 12 weeks. Treatment-emergent adverse events by year and cases/100 patient-years.

Results

109 patients were enrolled; 108 received ≥1 sparsentan dose; 103 entered the open-label extension (68 sparsentan, 35 irbesartan during the double-blind period). Sparsentan was ongoing in 45/108 patients (41.7%); median time to treatment discontinuation was 3.9 years (95% CI, 2.6-5.2). Mean percent proteinuria reduction from baseline was sustained through follow-up. Achieving partial remission within 9 months of first sparsentan dose (52.8% of patients) versus not achieving (47.2%) was associated with significantly slower rate of estimated glomerular filtration rate decline over the entire treatment period (-2.70 vs -6.56; P = 0.03) and in the first 2 years (-1.69 vs -6.46; P = 0.03). The most common treatment-emergent adverse events (>9 cases/100 patient-years) were headache, peripheral edema, upper respiratory infection, hyperkalemia, and hypotension. Peripheral edema and hypotension declined from year 1 (13.9% and 15.7% of patients, respectively) to ≤4% in years ≥2. There were no cases of heart failure and no patient deaths.

Limitations

The open-label extension does not include a comparison group.

Conclusions

Long-term sparsentan treatment showed sustained proteinuria reduction and a consistent safety profile.

Metabolic Acidosis in CKD: Pathogenesis, Adverse Effects, and Treatment Effects

Metabolic acidosis is a frequent complication of chronic kidney disease and is associated with a number of adverse outcomes, including worsening kidney function, poor musculoskeletal health, cardiovascular events, and death. Mechanisms that prevent metabolic acidosis detrimentally promote further kidney damage, creating a cycle between acid accumulation and acid-mediated kidney injury. Disrupting this cycle through the provision of alkali, most commonly using sodium bicarbonate, is hypothesized to preserve kidney function while also mitigating adverse effects of excess acid on bone and muscle. However, results from clinical trials have been conflicting. There is also significant interest to determine whether sodium bicarbonate might improve patient outcomes for those who do not have overt metabolic acidosis. Such individuals are hypothesized to be experiencing acid-mediated organ damage despite having a normal serum bicarbonate concentration, a state often referred to as subclinical metabolic acidosis. Results from small- to medium-sized trials in individuals with subclinical metabolic acidosis have also been inconclusive. Well-powered clinical trials to determine the efficacy and safety of sodium bicarbonate are necessary to determine if this intervention improves patient outcomes.

Urotensin II system in chronic kidney disease

Chronic kidney disease (CKD) is a progressive and long-term condition marked by a gradual decline in kidney function. CKD is prevalent among those with conditions such as diabetes mellitus, hypertension, and glomerulonephritis. Affecting over 10% of the global population, CKD stands as a significant cause of morbidity and mortality. Despite substantial advances in understanding CKD pathophysiology and management, there is still a need to explore novel mechanisms and potential therapeutic targets. Urotensin II (UII), a potent vasoactive peptide, has garnered attention for its possible role in the development and progression of CKD. The UII system consists of endogenous ligands UII and UII-related peptide (URP) and their receptor, UT. URP pathophysiology is understudied, but alterations in tissue expression levels of UII and UT and blood or urinary UII concentrations have been linked to cardiovascular and kidney dysfunctions, including systemic hypertension, chronic heart failure, glomerulonephritis, and diabetes. UII gene polymorphisms are associated with increased risk of diabetes. Pharmacological inhibition or genetic ablation of UT mitigated kidney and cardiovascular disease in rodents, making the UII system a potential target for slowing CKD progression. However, a deeper understanding of the UII system's cellular mechanisms in renal and extrarenal organs is essential for comprehending its role in CKD pathophysiology. This review explores the evolving connections between the UII system and CKD, addressing potential mechanisms, therapeutic implications, controversies, and unexplored concepts.

Endothelin receptor antagonists in diabetic and non-diabetic chronic kidney disease

Chronic kidney disease (CKD) is one of the major causes of morbidity and mortality, affecting >800 million persons globally. While we still lack efficient, targeted therapies addressing the major underlying pathophysiologic processes in CKD, findings of several recent trials have brought about a shifting landscape of promising therapies. The endothelin system has been implicated in the pathophysiology of CKD and endothelin receptor antagonists are one class of drugs for which we have increasing evidence of efficacy in these patients. In this review we summarize the most recent findings on the safety and efficacy of endothelin receptor antagonists in diabetic and non-diabetic CKD, future directions of research and upcoming treatments.

Focal Segmental Glomerulosclerosis Patient Baseline Characteristics in the Sparsentan Phase 3 DUPLEX Study

Introduction

The phase 3 DUPLEX trial is evaluating sparsentan, a novel, nonimmunosuppressive, single-molecule dual endothelin angiotensin receptor antagonist, in patients with focal segmental glomerulosclerosis (FSGS).

Methods

DUPLEX (NCT03493685) is a global, multicenter, randomized, double-blind, parallel-group, active-controlled study evaluating the efficacy and safety of sparsentan 800 mg once daily versus irbesartan 300 mg once daily in patients aged 8 to 75 years (USA/UK) and 18 to 75 years (ex-USA/UK) weighing ≥20 kg with biopsy-proven FSGS or documented genetic mutation in a podocyte protein associated with FSGS, and urine protein-to-creatinine ratio (UP/C) ≥1.5 g/g. Baseline characteristics blinded to treatment allocation are reported descriptively.

Results

The primary analysis population includes 371 patients (336 adult, 35 pediatric [<18 years]) who were randomized and received study drug (median age, 42 years). Patients were White (73.0%), Asian (13.2%), Black/African American (6.7%), or Other race (7.0%); and from North America (38.8%), Europe (36.1%), South America (12.7%), or Asia Pacific (12.4%). Baseline median UP/C was 3.0 g/g; 42.6% in nephrotic-range (UP/C >3.5 g/g [adults]; >2.0 g/g [pediatrics]). Patients were evenly distributed across estimated glomerular filtration rate (eGFR) categories corresponding to chronic kidney disease (CKD) stages 1 to 3b. Thirty-three patients (9.4% of 352 evaluable samples) had pathogenic or likely pathogenic (P/LP) variants of genes essential to podocyte structural integrity and function, 27 (7.7%) had P/LP collagen gene (COL4A3/4/5) variants, and 14 (4.0%) had high-risk APOL1 genotypes.

Conclusions

Patient enrollment in DUPLEX, the largest interventional study in FSGS to date, will enable important characterization of the treatment effect of sparsentan in a geographically broad and clinically diverse FSGS population.

[Immunoglobulin A nephropathy-New treatment possibilities]

Immunoglobulin A (IgA) nephropathy is the most frequent glomerulonephritis in adults in Central Europe. It is characterized by microhematuria and occasionally macrohematuria, proteinuria and a chronic loss of kidney function. The diagnosis is made based on a kidney biopsy. The progressive kidney damage must always be slowed down by normalizing blood pressure, using angiotensin inhibitors and consistently avoiding additional toxic substances. In many cases this is not sufficient and then sodium-glucose transporter 2 (SGLT-2) inhibitors and immunomodulators are used. In particular, the SGLT-2 inhibitors show a very significant reduction in proteinuria and slow down the deterioration of the estimated glomerular filtration rate (eGFR). While systemic corticosteroids are now only indicated in rare cases, a special budesonide formulation shows good effects. Further pathophysiologically based pharmacotherapies are currently being tested in clinical studies. These include, among others, the dual endothelin type A receptor and angiotensin II receptor antagonist sparsentan, which has already been shown to reduce proteinuria as well as inhibitors of complement activation, which is important for kidney damage. Initial findings for these as well as for the B‑lymphocyte proliferation inhibitor sibeprenlimab, suggest that they could enrich the armamentarium for the treatment of IgA nephropathy in the future.

Lessons learned from early-stage clinical trials for diabetic nephropathy

INTRODUCTION

The evolution of treatment for diabetic nephropathy illustrates how basic biochemistry and physiology have led to new agents such as SGLT2 inhibitors and mineralocorticoid blockers. Conversely, clinical studies performed with these agents have suggested new concepts for investigational drug development. We reviewed currently available treatments for diabetic nephropathy and then analyzed early clinical trials of new agents to assess the potential for future treatment modalities.

AREAS COVERED

We searched ClinicalTrials.gov for new agents under study for diabetic nephropathy in the past decade. Once we have identified investigation trials of new agents, we then used search engines and Pubmed.gov to find publications providing insight on these drugs. Current treatments have shown benefit in both cardiac and renal disease. In our review, we found 51 trials and 43 pharmaceuticals in a number of drug classes: mineralocorticoid blockers, anti-inflammatory, anti-fibrosis, nitric oxide stimulatory, and podocyte protection, and endothelin inhibitors.

EXPERT OPINION

It is difficult to predict which early phase treatments will advance to confirmatory clinical trials. Current agents are thought to improve hemodynamic function. However, the coincident benefit of both myocardial function and the glomerulus argues for primary effects at the subcellular level, and we follow the evolution of agents which modify fundamental cellular processes.

Safety, pharmacokinetics, and pharmacodynamics in healthy Chinese volunteers treated with SC0062, a highly selective endothelin-A receptor antagonist

This study evaluated the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and food effects (FE) of SC0062, a highly active endothelin-A (ETA ) receptor antagonist, in healthy subjects. The primary objectives of this first-in-human phase I study, comprised of single-ascending-dose, multiple-ascending-dose, and FE parts, were to characterize the safety and tolerability of SC0062, and FE. The secondary objectives were to determine the PK behavior of SC0062 and its major active metabolite M18, whereas exploratory objectives focused on PD effects, principally effects on endothelin-1 (ET-1) and total bile acids (TBA). Single doses of 10 to 100 mg and multiple daily doses of 20 and 50 mg for 6 days were well tolerated. SC0062 was rapidly absorbed and plasma exposure of SC0062 and M18 increased disproportionately with dose, achieving steady state by day 3, with accumulation ratios of 1.22 and 1.89 on day 6 for SC0062 and M18, respectively. The geometric mean (geometric standard deviation) terminal elimination half-life (t1/2 ) values of SC0062 and M18 were 7.25 (1.70) h and 13.73 (1.32) h, respectively. Plasma ET-1 concentrations were dose-proportional, whereas plasma TBA concentrations behaved erratically. Following a single 50 mg dose of SC0062 after a high-fat meal, Cmax values for SC0062 and M18 increased by 41% and 32%, respectively, and median Tmax values for SC0062 were 3 h longer than fasting values; exposure was unaffected. These favorable safety, PK, and PD results provide a foundation for further studies of SC0062 in pulmonary arterial hypertension, chronic kidney disease, and other relevant indications.

Central role of podocytes in mediating cellular cross talk in glomerular health and disease

Podocytes are highly specialized epithelial cells that surround the capillaries of the glomeruli in the kidney. Together with the glomerular endothelial cells, these postmitotic cells are responsible for regulating filtrate from the circulating blood with their organized network of interdigitating foot processes that wrap around the glomerular basement membrane. Although podocyte injury and subsequent loss is the hallmark of many glomerular diseases, recent evidence suggests that the cell-cell communication between podocytes and other glomerular and nonglomerular cells is critical for the development and progression of kidney disease. In this review, we highlight these key cellular pathways of communication and how they might be a potential target for therapy in glomerular disease. We also postulate that podocytes might serve as a central hub for communication in the kidney under basal conditions and in response to cellular stress, which may have implications for the development and progression of glomerular diseases.

The Role of the Endocrine System in the Regulation of Acid-Base Balance by the Kidney and the Progression of Chronic Kidney Disease

Systemic acid-base status is primarily determined by the interplay of net acid production (NEAP) arising from metabolism of ingested food stuffs, buffering of NEAP in tissues, generation of bicarbonate by the kidney, and capture of any bicarbonate filtered by the kidney. In chronic kidney disease (CKD), acid retention may occur when dietary acid production is not balanced by bicarbonate generation by the diseased kidney. Hormones including aldosterone, angiotensin II, endothelin, PTH, glucocorticoids, insulin, thyroid hormone, and growth hormone can affect acid-base balance in different ways. The levels of some hormones such as aldosterone, angiotensin II and endothelin are increased with acid accumulation and contribute to an adaptive increase in renal acid excretion and bicarbonate generation. However, the persistent elevated levels of these hormones can damage the kidney and accelerate progression of CKD. Measures to slow the progression of CKD have included administration of medications which inhibit the production or action of deleterious hormones. However, since metabolic acidosis accompanying CKD stimulates the secretion of several of these hormones, treatment of CKD should also include administration of base to correct the metabolic acidosis.

The Treatment of Primary IgA Nephropathy: Change, Change, Change

IgA nephropathy (IgAN) is the most common glomerular disease in the world. However, the approach to treatment remains controversial. There has been an explosion of clinical trials over the past decade both to further examine corticosteroid use and usher in additional treatment considerations, including 2 newly approved therapies for IgAN. Sodium glucose cotransporter 2 inhibitors are proving to be effective therapy across proteinuric chronic kidney diseases, and IgAN is not likely to be an exception. Further supportive agents are looking highly promising and so are novel agents that specifically focus on the pathophysiology of this disease, including endothelin blockade, complement inhibition, and B-cell targeted strategies. We suggest a present-day approach to treatment of individuals with IgAN, expose the limitations in our knowledge, and discuss new treatments that may arise, hoping they come with evidence about optimal utilization. Change appears to be inevitable for our approach to the treatment of IgA nephropathy. This is truly an exciting and optimistic time.

Practical Considerations for the Use of Sparsentan in the Treatment of Patients with IgAN in Clinical Practice

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. It is characterized by the mesangial deposition of IgA-containing immune complexes, triggering damage to the glomerular filtration barrier that is amplified by the tandem action of endothelin-1 and angiotensin II at their receptors. Proteinuria and progressive glomerular damage cause loss of kidney function in up to 50% of patients within 10-20 years. The risk of progression is strongly associated with persistent proteinuria (>0.75-1 g/day). Current standard of care involves interventions to decrease proteinuria and control blood pressure. Immunosuppressive agents, used in selected patients at high risk for progression, can be associated with significant side effects. Sparsentan, a novel non-immunosuppressive single-molecule Dual Endothelin Angiotensin Receptor Antagonist (DEARA), received FDA accelerated approval based on interim results from the PROTECT trial, which demonstrated that sparsentan-treated patients achieved a significantly greater reduction in proteinuria from baseline versus the active control irbesartan and that sparsentan was generally safe and well tolerated. Sparsentan is the first non-immunosuppressive treatment to be FDA-approved for the reduction of proteinuria in adults with IgAN at high risk of disease progression. We provide practical guidance for the clinical use of sparsentan in adults with IgAN.

Advances in the management of chronic kidney disease

Chronic kidney disease (CKD) represents a global public health crisis, but awareness by patients and providers is poor. Defined as persistent abnormalities in kidney structure or function for more than three months, manifested as either low glomerular filtration rate or presence of a marker of kidney damage such as albuminuria, CKD can be identified through readily available blood and urine tests. Early recognition of CKD is crucial for harnessing major advances in staging, prognosis, and treatment. This review discusses the evidence behind the general principles of CKD management, such as blood pressure and glucose control, renin-angiotensin-aldosterone system blockade, statin therapy, and dietary management. It additionally describes individualized approaches to treatment based on risk of kidney failure and cause of CKD. Finally, it reviews novel classes of kidney protective agents including sodium-glucose cotransporter-2 inhibitors, glucagon-like peptide-1 receptor agonists, non-steroidal selective mineralocorticoid receptor antagonists, and endothelin receptor antagonists. Appropriate, widespread implementation of these highly effective therapies should improve the lives of people with CKD and decrease the worldwide incidence of kidney failure.

Prevalence and predictors of chronic kidney disease among type 2 diabetic patients worldwide, systematic review and meta-analysis

BACKGROUND

Diabetes is a complicated, chronic condition that requires ongoing medical attention as well as multiple risk-reduction measures beyond glucose control. The prevalence of chronic kidney disease (CKD) is highly variable in different parts of the world due to various environmental, ethnic, socioeconomic, and rural-urban differences. Diabetes is the leading cause of CKD. This study aimed to estimate the global prevalence of CKD and its associated factors among type 2 diabetes(T2DM) patients, provide scientific evidence for a better understanding of the burden of CKD among diabetes mellitus type 2 patients, and design interventional strategies.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist guideline was followed for this review and meta-analysis. The electronic databases (Pub Med, Cochrane Library, Google Scholar, and grey literature) were searched to retrieve articles by using keywords. Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument was used to assess the quality of studies. The meta-analysis was conducted using STATA 17 software. The Meta logistic regression was computed to present the pooled prevalence and Odds ratio (OR) of the determinate factors with a 95% confidence interval (CI).

RESULTS

In this systematic review and meta-analysis 20 studies were done in 13 different countries. The pooled magnitude of chronic kidney disease among type 2 DM patients was 27% (95% CI 21%, 33%). The prevalence of chronic kidney disease differs across countries, with the maximum in the USA and the lowest in the United Arab Emirates. Patients with CKD have an elevated risk of severe renal and cardiovascular morbidity and mortality. Renin-angiotensin system inhibitors, sodium-glucose cotransporter-2 inhibitors, glucagon-like peptide 1 receptor agonists, and, more recently, non-steroidal mineralocorticoid receptor antagonists are among the medications that have been demonstrated to slow the progression of CKD. In this systematic review and meta-analysis increased age, obesity, having a history of type 2 diabetes mellitus, smoking history, presence of hypertension, and cardiac heart disease were factors significantly associated with the presence of chronic kidney disease among type 2 diabetic patients.

CONCLUSIONS

The prevalence of chronic kidney disease among type 2 diabetes mellitus patients was high based on the included 20 articles. The review reported that old age, hypertension, cardiac disease, smoking, obesity, and duration of diabetes mellitus was predictor variable for chronic kidney disease among type 2 diabetic patients. Therefore, in order to lower the morbidity and mortality from chronic kidney disease among type 2 diabetic patients, it is advised to develop both preventive and curative intervention strategies, such as raising awareness, creating a supportive environment, and prescribing appropriate medication at an early stage.

Pathomechanisms of Diabetic Kidney Disease

The worldwide occurrence of diabetic kidney disease (DKD) is swiftly rising, primarily attributed to the growing population of individuals affected by type 2 diabetes. This surge has been transformed into a substantial global concern, placing additional strain on healthcare systems already grappling with significant demands. The pathogenesis of DKD is intricate, originating with hyperglycemia, which triggers various mechanisms and pathways: metabolic, hemodynamic, inflammatory, and fibrotic which ultimately lead to renal damage. Within each pathway, several mediators contribute to the development of renal structural and functional changes. Some of these mediators, such as inflammatory cytokines, reactive oxygen species, and transforming growth factor β are shared among the different pathways, leading to significant overlap and interaction between them. While current treatment options for DKD have shown advancement over previous strategies, their effectiveness remains somewhat constrained as patients still experience residual risk of disease progression. Therefore, a comprehensive grasp of the molecular mechanisms underlying the onset and progression of DKD is imperative for the continued creation of novel and groundbreaking therapies for this condition. In this review, we discuss the current achievements in fundamental research, with a particular emphasis on individual factors and recent developments in DKD treatment.

Zibotentan in combination with dapagliflozin compared with dapagliflozin in patients with chronic kidney disease (ZENITH-CKD): a multicentre, randomised, active-controlled, phase 2b, clinical trial

BACKGROUND

In patients with chronic kidney disease, SGLT2 inhibitors and endothelin A receptor antagonists (ERAs) can reduce albuminuria and glomerular filtration rate (GFR) decline. We assessed the albuminuria-lowering efficacy and safety of the ERA zibotentan combined with the SGLT2 inhibitor dapagliflozin.

METHODS

ZENITH-CKD was a multicentre, randomised, double-blind, active-controlled clinical trial, done in 170 clinical practice sites in 18 countries. Adults (≥18 to ≤90 years) with an estimated GFR (eGFR) of 20 mL/min per 1·73 m2 or greater and a urinary albumin-to-creatinine ratio (UACR) of 150-5000 mg/g were randomly assigned (2:1:2) to 12 weeks of daily treatment with zibotentan 1·5 mg plus dapagliflozin 10 mg, zibotentan 0·25 mg plus dapagliflozin 10 mg, or dapagliflozin 10 mg plus placebo, as adjunct to angiotensin-converting enzyme inhibitors or angiotensin receptor blockers if tolerated. The primary endpoint was a change from baseline in log-transformed UACR (zibotentan 1·5 mg plus dapagliflozin vs dapagliflozin plus placebo) at week 12. Fluid retention was an event of special interest, defined as an increase in bodyweight of at least 3% (at least 2·5% must have been from total body water) from baseline or an increase of at least 100% in B-type natriuretic peptide (BNP) and either a BNP concentration greater than 200 pg/mL if without atrial fibrillation or BNP greater than 400 pg/mL if with atrial fibrillation. This trial is registered with ClinicalTrials.gov, NCT04724837, and is completed.

FINDINGS

Between April 28, 2021, and Jan 17, 2023, we assessed 1492 participants for eligibility. For the main analysis, we randomly assigned 449 (30%) participants, 447 (99%) of whom (mean age 62·8 years [SD 12·1], 138 [31%] female, 309 [69%] male, 305 [68%] White, mean eGFR 46·7 mL/min per 1·73 m2 [SD 22·4], and median UACR 565·5 mg/g [IQR 243·0-1212·6]) received treatment with zibotentan 1·5 mg plus dapagliflozin (n=179 [40%]), zibotentan 0·25 mg plus dapagliflozin (n=91 [20%]), or dapagliflozin plus placebo (n=177 [40%]). Zibotentan 1·5 mg plus dapagliflozin and zibotentan 0·25 mg plus dapagliflozin reduced UACR versus dapagliflozin plus placebo throughout the treatment period of the study. At week 12, the difference in UACR versus dapagliflozin plus placebo was -33·7% (90% CI -42·5 to -23·5; p<0·0001) for zibotentan 1·5 mg plus dapagliflozin and -27·0% (90% CI -38·4 to -13·6; p=0·0022) for zibotentan 0·25 mg plus dapagliflozin. Fluid-retention events were observed in 33 (18%) of 179 participants in the zibotentan 1·5 mg plus dapagliflozin group, eight (9%) of 91 in the zibotentan 0·25 mg plus dapagliflozin group, and 14 (8%) of 177 in the dapagliflozin plus placebo group.

INTERPRETATION

Zibotentan combined with dapagliflozin reduced albuminuria with an acceptable tolerability and safety profile and is an option to reduce chronic kidney disease progression in patients already receiving currently recommended therapy.

FUNDING

AstraZeneca.

Global burden and influencing factors of chronic kidney disease due to type 2 diabetes in adults aged 20-59 years, 1990-2019

Population structure and lifestyles may have contributed to the epidemiological status of Chronic Kidney Disease due to Type 2 Diabetes (CKD-T2D). This study is a secondary data analysis. Using data from the Global Burden of Disease Study, we describe the changes in CKD-T2D burden and its influencing factors in the population aged 20-59 years from 1990 to 2019. Globally, the incidence, death, and Disability Adjusted Life Years (DALYs) rate of CKD-T2D showed an upward trend and increased with age, and the burden in males was higher than that in females. Population growth and aging were important driving factors for the increase of CKD-T2D DALY burden, while high systolic blood pressure and high body-mass index were the primary attributable risk factors. High body-mass index exhibited higher contributions to high Socioeconomic Development Index (SDI) countries, whereas low SDI countries were more impacted by high systolic blood pressure. The population attributable fraction of CKD-T2D DALY caused by high body-mass index was positively correlated with SDI, while high temperature and lead exposure were negatively correlated. Therefore, strengthening disease screening for people aged 20-59 years and formulating early intervention measures based on the level of socioeconomic development may effectively alleviate the burden of CKD-T2D.

Targeting the Endothelin A Receptor in IgA Nephropathy

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and carries a substantial risk of kidney failure. New agency-approved therapies, either specifically for IgAN or for chronic kidney disease (CKD) in general, hold out hope for mitigating renal deterioration in patients with IgAN. The latest addition to this therapeutic armamentarium targets the endothelin-A receptor (ETAR). Activation of ETAR on multiple renal cell types elicits a host of pathophysiological effects, including vasoconstriction, cell proliferation, inflammation, apoptosis, and fibrosis. Blockade of ETAR is renoprotective in experimental models of IgAN and reduces proteinuria in patients with IgAN. This review discusses the evidence supporting the use of ETAR blockade in IgAN as well as addressing the potential role for this class of agents among the current and emerging therapies for treating this disorder.

A combination of 5/6-nephrectomy and unilateral ureteral obstruction model accelerates progression of remote organ fibrosis in chronic kidney disease

Chronic kidney disease (CKD) involves progressive renal fibrosis, which gradually reduces kidney function and often causes various complications in extrarenal tissues. Therefore, we investigated fibrogenesis in extrarenal tissues (heart, liver, and lungs) in different experimental CKD models, such as the 5/6-nephrectomy (5/6 Nx), unilateral ureteral obstruction (UUO), and a combination (2/3 Nx + UUO). We evaluated the degree of fibrogenesis in kidneys and extrarenal tissues by histological analysis and quantification of fibrosis-related gene and protein expression. To elucidate the fibrosis mechanisms observed in 2/3 Nx + UUO mice, we evaluated the effect of indoxyl sulfate (IS), a typical uremic toxin accumulated in CKD, and transforming growth factor-β (TGF-β), a fibrosis-related factor, on fibrosis using human hepatoma (HepG2) and RAW264.7 cells. A significant decline in renal function was observed in the 5/6 Nx and 2/3 Nx + UUO models, whereas a significant increase in renal fibrosis was observed only in the obstructed kidneys. Notable amount of fibrosis was induced in the liver and heart in the 2/3 Nx + UUO model, with the induction of macrophage infiltration and increased tissue IS and TGF-β levels. In agreement with the results of in vivo experiments, co-stimulation with IS, TGF-β, and macrophage-conditioned medium increased the expression of fibrogenic genes in HepG2 cells. We demonstrated that the 2/3 Nx + UUO model induced both loss of renal function and renal fibrosis in the earlier stages, providing a novel CKD model that induces remote organ fibrosis in a shorter time.

Obstructive nephropathy and molecular pathophysiology of renal interstitial fibrosis

The kidneys play a key role in maintaining total body homeostasis. The complexity of this task is reflected in the unique architecture of the organ. Ureteral obstruction greatly affects renal physiology by altering hemodynamics, changing glomerular filtration and renal metabolism, and inducing architectural malformations of the kidney parenchyma, most importantly renal fibrosis. Persisting pathological changes lead to chronic kidney disease, which currently affects ∼10% of the global population and is one of the major causes of death worldwide. Studies on the consequences of ureteral obstruction date back to the 1800s. Even today, experimental unilateral ureteral obstruction (UUO) remains the standard model for tubulointerstitial fibrosis. However, the model has certain limitations when it comes to studying tubular injury and repair, as well as a limited potential for human translation. Nevertheless, ureteral obstruction has provided the scientific community with a wealth of knowledge on renal (patho)physiology. With the introduction of advanced omics techniques, the classical UUO model has remained relevant to this day and has been instrumental in understanding renal fibrosis at the molecular, genomic, and cellular levels. This review details key concepts and recent advances in the understanding of obstructive nephropathy, highlighting the pathophysiological hallmarks responsible for the functional and architectural changes induced by ureteral obstruction, with a special emphasis on renal fibrosis.

The sodium glucose co-transporter 2 inhibitor dapagliflozin ameliorates the fluid-retaining effect of the endothelin A receptor antagonist zibotentan

BACKGROUND

Endothelin A receptor antagonists (ETARA) slow chronic kidney disease (CKD) progression but their use is limited due to fluid retention and associated clinical risks. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) cause osmotic diuresis and improve clinical outcomes in CKD and heart failure. We hypothesized that co-administration of the SGLT2i dapagliflozin with the ETARA zibotentan would mitigate the fluid retention risk using hematocrit (Hct) and bodyweight as proxies for fluid retention.

METHODS

Experiments were performed in 4% salt fed WKY rats. First, we determined the effect of zibotentan (30, 100 or 300 mg/kg/day) on Hct and bodyweight. Second, we assessed the effect of zibotentan (30 or 100 mg/kg/day) alone or in combination with dapagliflozin (3 mg/kg/day) on Hct and bodyweight.

RESULTS

Hct at Day 7 was lower in zibotentan versus vehicle groups [zibotentan 30 mg/kg/day, 43% (standard error 1); 100 mg/kg/day, 42% (1); and 300 mg/kg/day, 42% (1); vs vehicle, 46% (1); P < .05], while bodyweight was numerically higher in all zibotentan groups compared with vehicle. Combining zibotentan with dapagliflozin for 7 days prevented the change in Hct [zibotentan 100 mg/kg/day and dapagliflozin, 45% (1); vs vehicle 46% (1); P = .44] and prevented the zibotentan-driven increase in bodyweight (zibotentan 100 mg/kg/day + dapagliflozin 3 mg/kg/day = -3.65 g baseline corrected bodyweight change; P = .15).

CONCLUSIONS

Combining ETARA with SGLT2i prevents ETARA-induced fluid retention, supporting clinical studies to assess the efficacy and safety of combining zibotentan and dapagliflozin in individuals with CKD.

Renal Glomerular Expression of WT-1, TGF-β, VEGF, and ET-1 Immunostains in Murine Models of Focal and Segmental Glomerulosclerosis

Primary focal segmental glomerulosclerosis (FSGS) is a type of chronic renal disease that commonly progresses to renal failure as the treatments are not particularly effective. Glomerular podocyte injury and loss are pivotal to the pathogenesis of FSGS. This study aims to explore the glomerular immunohistochemistry stain expression of Wilms tumor-1 (WT-1) (podocyte-specific protein), transforming growth factor beta (TGF-β) (cytokine protein), vascular endothelial growth factor (VEGF) (angiogenic protein), and endothelin-1 (ET-1) (profibrotic growth factor), in rats with adriamycin nephropathy, which represents the murine model of human FSGS. By the end of 8 and 12 weeks, the kidneys of adriamycin-treated rats and control rats were harvested and the histomorphology was studied. Both 8- and 12-week test groups developed proteinuria, and hypoalbuminemia and showed FSGS on hematoxylin and eosin-stained slides. The renal tissue samples were also treated with immunostains for WT-1, TGF-β, VEGF, and ET-1. The glomeruli in all the FSGS kidneys showed loss of WT-1 expression with a concomitant notable increased expression of TGF-β, VEGF, and ET-1 immunostains. These results demonstrate that as FSGS evolves, the WT-1-expressing podocytes are lost and it correlates inversely with the overexpression of TGF-β, VEGF, and ET-1, suggesting that during the pathogenesis of FSGS, podocyte damage triggers the activation of these proteins. The findings in the current study echo the theory hypothesized in world literature that TGF-β, VEGF, and ET-1 play an integral part in the evolution of FSGS. More research is needed to further detail the pathogenic role of these proteins as it may open routes to more targeted and effective treatment modalities.

Hypertension and Dyslipidemia: the Two Partners in Endothelium-Related Crime

PURPOSE OF REVIEW

The goal of this article is to characterize the endothelium's role in the development of hypertension and dyslipidemia and to point out promising therapeutic directions.

RECENT FINDINGS

Dyslipidemia may facilitate the development of hypertension, whereas the collaboration of these two silent killers potentiates the risk of atherosclerosis. The common pathophysiological denominator for hypertension and dyslipidemia is endothelial cell dysfunction, which manifests as dysregulation of homeostasis, redox balance, vascular tone, inflammation, and thrombosis. Treatment focused on mediators acting in these processes might be groundbreaking. Metabolomic research on hypertension and dyslipidemia has revealed new therapeutic targets. State-of-the-art solutions integrating interview, clinical examination, innovative imaging, and omics profiles along with artificial intelligence have been already shown to improve patients' risk stratification and treatment. Pathomechanisms underlying hypertension and dyslipidemia take place in the endothelium. Novel approaches involving endothelial biomarkers and bioinformatics advances could open new perspectives in patient management.

Knowledge Translation in Glomerulonephritis: Successes in Translational Research From the Bench to Bedside

Purpose of review

Glomerulonephritis refers to a rare group of diseases characterized by glomerular inflammation, which collectively are a common cause of kidney failure. Until recently, there was a lack of high-quality clinical trials to inform the care of patients with glomerulonephritides. We identified examples of successful translational research spanning from basic science to clinical applications, and highlight gaps in implementation science.

Sources of information

The focus of our review was derived from discussions between health care professionals, researchers, and patient partners. We also performed literature searches pertaining to the treatment of glomerulonephritis in PubMed and Google Scholar.

Methods

Examples of successful knowledge translation were generated through review of new evidence in the past 5 years and by iterative discussions by the authors. We then conducted a narrative review of several themes related to knowledge translation in glomerulonephritis. This was complemented by an interview with a patient partner to provide an example of a patient's perspective living with glomerulonephritis.

Key findings

We summarized selected recent advances in glomerulonephritis and its knowledge translation in the following domains: (1) identification of auto-antibodies in membranous nephropathy and minimal change disease; (2) clinical trials of novel targeted therapies for IgA nephropathy and lupus nephritis, which have led to approval of new treatments; (3) developments in research networks and clinical trials in glomerulonephritis; (4) recognition of the importance in developing standardized patient reported outcome measures in clinical trials; and (5) barriers in knowledge translation including access to medication.

Limitations

A systematic search of the literature and formal assessment of quality of evidence were beyond the scope of this review.

IgA Nephropathy: Current Treatment and New Insights

IgA Nephropathy (IgAN) is the most common cause of primary glomerulonephritis worldwide. Despite the histopathologic hallmark of mesangial IgA deposition, IgAN is a heterogenous autoimmune disease not only in terms of clinical presentation but also in long-term disease progression. The pathogenesis of the disease is complex and includes the generation of circulating IgA immune complexes with chemical and biological characteristics that favor mesangial deposition and reaction to mesangial under-glycosylated IgA1 accumulation, which leads to tissue injury with glomerulosclerosis and interstitial fibrosis. Patients with proteinuria over 1 g, hypertension, and impaired renal function at diagnosis are considered to be at high risk for disease progression and end-stage kidney disease (ESKD). Glucocorticoids have been the mainstay of treatment for these patients for years, but without long-term benefit for renal function and accompanied by several adverse events. A better understanding of the pathophysiology of IgAN in recent years has led to the development of several new therapeutic agents. In this review, we summarize the current therapeutic approach for patients with IgAN as well as all novel investigational agents.

Research progress on the role of ET-1 in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the common complications of diabetes mellitus, which usually progresses to end-stage renal disease and causes great damage to the health of patients. Endothelin-1 (ET-1), a molecule closely associated with the progression of DKD, has increased expression in response to high glucose stimulation and is involved in hemodynamic changes, inflammation, glomerular and tubular dysfunction in the kidney, causing an increase in proteinuria and a decrease in glomerular filtration function, ultimately leading to glomerulosclerosis and renal failure. This paper aims to review the molecular level changes, regulatory mechanisms, and mechanisms of action of ET-1 under DKD, clinical trials of ET-1 receptor antagonists in recent years and current problems, to provide basic information and new research directions and ideas for the treatment of DKD and ET-1-related research.

Cardiorenal syndrome and diabetes: an evil pairing

Cardiorenal syndrome (CRS) is a pathology where the heart and kidney are involved, and the deterioration of one of them leads to the malfunction of the other. Diabetes mellitus (DM) carries a higher risk of HF and a worse prognosis. Furthermore, almost half of people with DM will have chronic kidney disease (CKD), which means that DM is the main cause of kidney failure. The triad of cardiorenal syndrome and diabetes is known to be associated with increased risk of hospitalization and mortality. Cardiorenal units, with a multidisciplinary team (cardiologist, nephrologist, nursing), multiple tools for diagnosis, as well as new treatments that help to better control cardio-renal-metabolic patients, offer holistic management of patients with CRS. In recent years, the appearance of drugs such as sodium-glucose cotransporter type 2 inhibitors, have shown cardiovascular benefits, initially in patients with type 2 DM and later in CKD and heart failure with and without DM2, offering a new therapeutic opportunity, especially for cardiorenal patients. In addition, glucagon-like peptide-1 receptor agonists have shown CV benefits in patients with DM and CV disease in addition to a reduced risk of CKD progression.

Sildenafil and Kidney Function in Heart Failure with Preserved Ejection Fraction

Key Points

Sildenafil induced an acute effect on eGFR without change in the overall eGFR slope after 24 weeks in a heart failure with preserved ejection fraction (HFpEF) cohort. N -terminal pro–brain natriuretic peptide levels and baseline diuretic use were most strongly associated with eGFR decline in this HFpEF cohort. Long-term studies are required to determine sildenafil's influence on kidney function and outcomes in HFpEF.

Background

CKD worsens the prognosis for people with heart failure with preserved ejection fraction (HFpEF). In the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic HFpEF (RELAX) trial, sildenafil decreased eGFR compared with placebo despite favorable kidney effects in preclinical models. Since acute eGFR decline precedes long-term kidney benefits for select medications, we assessed the influence of sildenafil on acute and chronic eGFR slopes.

Methods

The RELAX trial randomized 216 participants to placebo or sildenafil and assessed 24-week changes in cardiopulmonary exercise testing, cardiovascular imaging, and laboratory data. We applied linear mixed modeling to calculate the total, acute (0–12 weeks), and chronic (3–24 weeks) eGFR slopes by treatment. Using regression modeling, we assessed respective associations between eGFR slope and baseline data and clinical end points. We repeated the analyses using a binary outcome on the basis of a substantial (≥20%) decline in eGFR.

Results

The mean baseline eGFR was 60.8 ml/min per 1.73 m2, and the mean eGFR slope during follow-up was −3.21 ml/min per 1.73 m2 per year. Sildenafil did not alter total eGFR slope compared with placebo (difference +0.47 ml/min per 1.73 m2 per year, 95% confidence interval [CI], −6.63 to 7.57 ml/min per 1.73 m2 per year). Sildenafil users tended to experience a more negative acute eGFR slope (difference −3.15 ml/min per 1.73 m2 per year) and more positive chronic slope (+2.06 ml/min per 1.73 m2 per year) compared with placebo, but neither difference reached statistical significance. Baseline N -terminal pro–B-type natriuretic peptide and loop diuretic use were associated with worse eGFR trajectory regardless of treatment. Substantial eGFR decline was associated with increase in endothelin-1 and a greater risk of hospitalization or death (HR, 2.34, 95% CI, 1.21 to 4.53, P =0.01).

Conclusions

Sildenafil induced an acute effect on eGFR without change in the overall eGFR slope after 24 weeks in an HFpEF cohort, suggesting lack of long-term risk related to early reduction in eGFR after initiating treatment. Long-term studies are needed to determine the effect of sildenafil on kidney function in HFpEF.

IgA Nephropathy Patient Baseline Characteristics in the Sparsentan PROTECT Study

Introduction

Sparsentan is a novel single-molecule dual endothelin angiotensin receptor antagonist with hemodynamic and anti-inflammatory properties and is not an immunosuppressant. The ongoing phase 3 PROTECT trial examines sparsentan in adults with IgA nephropathy (IgAN).

Methods

The PROTECT trial (NCT03762850) is a multicenter, international, randomized, double-blind, parallel-group, active-controlled study. The efficacy and safety of sparsentan versus the active control irbesartan is being evaluated in adults with biopsy-proven IgAN and proteinuria ≥1.0 g/d despite maximized treatment with an angiotensin-converting enzyme inhibitor (ACEi) and/or angiotensin receptor blocker (ARB) for at least 12 weeks. Blinded and aggregated baseline characteristics are reported descriptively and compared to contemporary phase 3 trials with patients with IgAN.

Results

The primary analysis population includes 404 patients who were randomized and received study drug (median age, 46 years). Enrolled patients were from Europe (53%), Asia Pacific (27%), and North America (20%). Baseline median urinary protein excretion was 1.8 g/d. The range of estimated glomerular filtration rate (eGFR) was broad with the largest proportion of patients (35%) in chronic kidney disease (CKD) stage 3B. Before transitioning to study medication, mean systolic/diastolic blood pressure was 129/82 mm Hg, with the majority of patients (63.4%) receiving the maximum labeled ACEi or ARB dose. Patients in Asian versus non-Asian regions included a higher percentage of females, had lower blood pressures, and included lower proportions of patients with a history of hypertension and baseline antihypertensive treatment.

Conclusions

Patient enrollment in PROTECT, with differing racial backgrounds and across CKD stages, will allow for important characterization of the treatment effect of sparsentan in patients with IgAN with proteinuria at high risk of kidney failure.

RhoA/ROCK inhibition attenuates endothelin-1-induced elevated glomerular permeability to albumin, inflammation, and fibrosis

Endothelin-1 (ET-1) contributes to the development of kidney diseases. However, the underlying molecular mechanism is largely undefined. Here we sought to investigate the potential role of ET-1 receptors, ET_A and ET_B in the regulation of increased glomerular permeability and underlying signaling pathways post-ET-1 infusion. Male Sprague-Dawley rats were infused with ET-1 (2 pmol/kg per minute, i.v.) for four weeks, and the effect on glomerular permeability to albumin (P_alb) and albuminuria was measured. The selective ROCK-1/2 inhibitor, Y-27632, was administered to a separate group of rats to determine its effect on ET-1-induced P_alb and albuminuria. The role of ET_A and ET_B receptors in regulating RhoA/ROCK activity was determined by incubating isolated glomeruli from normal rats with ET-1 and with selective ET_A and ET_B receptor antagonists. ET-1 infusion for four weeks significantly elevated P_alb and albuminuria. Y-27632 significantly reduced the elevation of P_alb and albuminuria. The activities of both RhoA and ROCK-1/2 were increased by ET-1 infusion. Selective ET_B receptor antagonism had no effect on the elevated activity of both RhoA and ROCK-1/2 enzymes. Selective ET_A receptor and combined ET_A/ET_B receptors blockade restored the activity of RhoA and ROCK-1/2 to normal levels. In addition, chronic ET-1 infusion increased the levels of glomerular inflammatory and fibrotic markers. These effects were all attenuated in rats following ROCK-1/2 inhibition. These observations suggest that ET-1 contributes to increased albuminuria, inflammation, and fibrosis by modulating the activity of the ET_A-RhoA/ROCK-1/2 pathway. Selective ET_A receptor blockade may represent a potential therapeutic strategy to limit glomerular injury and albuminuria in kidney disease.

Efficacy and safety of drugs for people with type 2 diabetes mellitus and chronic kidney disease on kidney and cardiovascular outcomes: A systematic review and network meta-analysis of randomized controlled trials

AIM

To evaluate the comparative efficacy and safety of promising kidney protection drugs, including sodium-glucose cotransporter-2 inhibitors (SGLT-2Is), glucagon-like peptide-1 receptor agonists (GLP-1RAs), dipeptidyl-peptidase IV Inhibitors (DPP-4Is), aldosterone receptor agonists (MRAs), endothelin receptor antagonist (ERAs), pentoxifylline (PTF), and pirfenidone (PFD), on cardiovascular and kidney outcomes in type 2 diabetes (T2DM) and chronic kidney disease (CKD) population.

METHODS

PubMed, Embase, and Cochrane Library were searched from inception to August 12, 2022. We used the Bayesian model for network meta-analyses, registered in the PROSPERO (CRD42022343601).

RESULTS

This network meta-analysis identified 2589 citations, and included 27 eligible trials, enrolling 50,237 patients. All results presented below were moderate to high quality. For kidney outcomes, SGLT-2Is were optimal in terms of reducing composite kidney events (RR 0.69, 95%CI 0.61-0.79), and slowing eGFR slope (MD1.34, 95%CI 1.06-1.62). Then MRAs (RR 0.77, 95%CI 0.68-0.88; MD 1.31, 95%CI 0.89-1.74), GLP-1RAs (RR 0.78, 95%CI 0.62-0.97; MD 0.75, 95%CI 0.46-1.05), and ERAs (RR 0.75, 95%CI 0.57-0.99; MD 0.7, 95%CI 0.3-1.1) were followed in parallel. For cardiovascular outcomes, SGLT-2 inhibitors were also among the best for lowing the risk of heart failure hospitalization (RR 0.67, 95%CI 0.57-0.78), followed by GLP-1RAs (RR 0.73, 95%CI 0.55-0.97) and MRAs (RR 0.79, 95%CI 0.67-0.92). SGLT-2Is (RR 0.8, 95%CI 0.71-0.89) and GLP-1RAs (RR 0.72, 95%CI 0.6-0.86) had comparable effects to reduce the risk of major adverse cardiovascular events. MRAs were possibly associated with increased drug discontinuation due to adverse events (RR 1.21, 95%CI 1.05-1.38). For the hyperkalemia outcome, MRAs (RR 2.08, 95%CI 1.86-2.33) were linked to the risk of hyperkalemia, whereas SGLT-2Is (RR 0.78, 95%CI 0.65-0.93) were in contrast.

CONCLUSIONS

SGLT-2Is significantly reduced kidney and cardiovascular risk in T2DM and CKD, subsequently GLP-1RAs and MRAs. SGLT-2Is-MRAs combination might be a recommended treatment regimen for maximizing kidney and cardiovascular protection but with a low risk of hyperkalemia in T2DM and CKD.

Sparsentan in patients with IgA nephropathy: a prespecified interim analysis from a randomised, double-blind, active-controlled clinical trial

BACKGROUND

Sparsentan is a novel, non-immunosuppressive, single-molecule, dual endothelin and angiotensin receptor antagonist being examined in an ongoing phase 3 trial in adults with IgA nephropathy. We report the prespecified interim analysis of the primary proteinuria efficacy endpoint, and safety.

METHODS

PROTECT is an international, randomised, double-blind, active-controlled study, being conducted in 134 clinical practice sites in 18 countries. The study examines sparsentan versus irbesartan in adults (aged ≥18 years) with biopsy-proven IgA nephropathy and proteinuria of 1·0 g/day or higher despite maximised renin-angiotensin system inhibitor treatment for at least 12 weeks. Participants were randomly assigned in a 1:1 ratio to receive sparsentan 400 mg once daily or irbesartan 300 mg once daily, stratified by estimated glomerular filtration rate at screening (30 to <60 mL/min per 1·73 m² and ≥60 mL/min per 1·73 m²) and urine protein excretion at screening (≤1·75 g/day and >1·75 g/day). The primary efficacy endpoint was change from baseline to week 36 in urine protein-creatinine ratio based on a 24-h urine sample, assessed using mixed model repeated measures. Treatment-emergent adverse events (TEAEs) were safety endpoints. All endpoints were examined in all participants who received at least one dose of randomised treatment. The study is ongoing and is registered with ClinicalTrials.gov, NCT03762850.

FINDINGS

Between Dec 20, 2018, and May 26, 2021, 404 participants were randomly assigned to sparsentan (n=202) or irbesartan (n=202) and received treatment. At week 36, the geometric least squares mean percent change from baseline in urine protein-creatinine ratio was statistically significantly greater in the sparsentan group (-49·8%) than the irbesartan group (-15·1%), resulting in a between-group relative reduction of 41% (least squares mean ratio=0·59; 95% CI 0·51-0·69; p<0·0001). TEAEs with sparsentan were similar to irbesartan. There were no cases of severe oedema, heart failure, hepatotoxicity, or oedema-related discontinuations. Bodyweight changes from baseline were not different between the sparsentan and irbesartan groups.

INTERPRETATION

Once-daily treatment with sparsentan produced meaningful reduction in proteinuria compared with irbesartan in adults with IgA nephropathy. Safety of sparsentan was similar to irbesartan. Future analyses after completion of the 2-year double-blind period will show whether these beneficial effects translate into a long-term nephroprotective potential of sparsentan.

FUNDING

Travere Therapeutics.

Renal hemodynamic changes in patients with type 2 diabetes and their clinical impact

The dysfunction of the internal mechanics within the kidney's filtering units, known as glomeruli, has been linked to the emergence and progression of diabetic kidney disease (DKD). To better understand this crucial aspect of kidney function and the pathology of DKD, a variety of methods are employed in research, from the introduction of external compounds, such as inulin, iohexol, iothalamate and p-aminohippurate, to cutting-edge imaging techniques and computational analysis. Given the significance of intraglomerular hemodynamic dysfunction in the pathogenesis and treatment of DKD, it is essential to thoroughly examine the available data on this topic. Accordingly, the aim of this review is to provide a comprehensive appraisal of the role of intraglomerular hemodynamic dysfunction in the development of DKD and the effects of current therapies used to mitigate DKD. Through this analysis, we can gain a deeper understanding of the complex pathogenesis of DKD and potentially discover new avenues for tailored therapeutic management of patients with DKD.

Targeting Glomerular Hemodynamics for Kidney Protection

The kidney microcirculation is a unique structure as it is composed to 2 capillary beds in series: the glomerular and peritubular capillaries. The glomerular capillary bed is a high-pressure capillary bed, having a 60 mm Hg to 40 mm Hg pressure gradient, capable of producing an ultrafiltrate of plasma quantified as the glomerular filtration rate (GFR), thereby allowing for waste products to be removed and establishing sodium/volume homeostasis. Entering the glomerulus is the afferent arteriole, and the exiting one is the efferent arteriole. The concerted resistance of each of these arterioles is what is known as glomerular hemodynamics and is responsible for increasing or decreasing GFR and renal blood flow. Glomerular hemodynamics play an important role in how homeostasis is achieved. Minute-to-minute fluctuations in the GFR are achieved by constant sensing of distal delivery of sodium and chloride in the specialized cells called macula densa leading to upstream alternation in afferent arteriole resistance altering the pressure gradient for filtration. Specifically, 2 classes of medications (sodium glucose cotransporter-2 inhibitors and renin-angiotensin system blockers) have shown to be effective in long-term kidney health by altering glomerular hemodynamics. This review will discuss how tubuloglomerular feedback is achieved, and how different disease states and pharmacologic agents alter glomerular hemodynamics.

Clinical trials with reno-vascular end points in patients with diabetes: Changing the scenario over the past 20 years

Major clinical advances over the last 20 years in the area of diabetic kidney disease (DKD) have been confirmed in large seminal clinical trials. These findings add to the previously identified benefits resulting from intensive glucose and blood pressure control therapies. Furthermore, newer glucose lowering treatments such as SGLT2 inhibitors and GLP-1 agonists appear very promising and are likely to transform the management and outlook of DKD over the next decade. In addition, novel mineralocorticoid receptor antagonists and a recently reported trial with an endothelin receptor blocker also have the potential to change clinical practice.

Diabetic Kidney Care Redefined with a New Way into Remission

Diabetic kidney disease has been a leading cause for end-stage kidney disease. Traditional methods to slow progression include tight glycemic control, blood pressure control, and use of renin-angiotensin axis inhibitors. Finerenone and sodium glucose co-transporters have shown proven benefit in diabetic kidney disease regression recently. Other potential targets for slowing the decline in diabetic kidney disease are transforming growth factor beta, endothelin antagonist, protein kinase C inhibitors, advanced glycation end product inhibition, Janus kinase-signal transducer and activator of transcription pathway inhibition, phosphodiesterase 3 or 5 inhibitors, and Rho kinase inhibitor. These targets are at various trial phases and so far, show promising results.

Stem Cells in Kidney Ischemia: From Inflammation and Fibrosis to Renal Tissue Regeneration

Ischemic nephropathy consists of progressive renal function loss due to renal hypoxia, inflammation, microvascular rarefaction, and fibrosis. We provide a literature review focused on kidney hypoperfusion-dependent inflammation and its influence on renal tissue's ability to self-regenerate. Moreover, an overview of the advances in regenerative therapy with mesenchymal stem cell (MSC) infusion is provided. Based on our search, we can point out the following conclusions: 1. endovascular reperfusion is the gold-standard therapy for RAS, but its success mostly depends on treatment timeliness and a preserved downstream vascular bed; 2. anti-RAAS drugs, SGLT2 inhibitors, and/or anti-endothelin agents are especially recommended for patients with renal ischemia who are not eligible for endovascular reperfusion for slowing renal damage progression; 3. TGF-β, MCP-1, VEGF, and NGAL assays, along with BOLD MRI, should be extended in clinical practice and applied to a pre- and post-revascularization protocols; 4. MSC infusion appears effective in renal regeneration and could represent a revolutionary treatment for patients with fibrotic evolution of renal ischemia.

Pathogenesis of Chronic Kidney Disease Is Closely Bound up with Alzheimer's Disease, Especially via the Renin-Angiotensin System

Chronic kidney disease (CKD) is a clinical syndrome secondary to the definitive change in function and structure of the kidney, which is characterized by its irreversibility and slow and progressive evolution. Alzheimer's disease (AD) is characterized by the extracellular accumulation of misfolded β-amyloid (Aβ) proteins into senile plaques and the formation of neurofibrillary tangles (NFTs) containing hyperphosphorylated tau. In the aging population, CKD and AD are growing problems. CKD patients are prone to cognitive decline and AD. However, the connection between CKD and AD is still unclear. In this review, we take the lead in showing that the development of the pathophysiology of CKD may also cause or exacerbate AD, especially the renin-angiotensin system (RAS). In vivo studies had already shown that the increased expression of angiotensin-converting enzyme (ACE) produces a positive effect in aggravating AD, but ACE inhibitors (ACEIs) have protective effects against AD. Among the possible association of risk factors in CKD and AD, we mainly discuss the RAS in the systemic circulation and the brain.

Endothelin Receptor Antagonists in Kidney Disease

Endothelin (ET) is found to be increased in kidney disease secondary to hyperglycaemia, hypertension, acidosis, and the presence of insulin or proinflammatory cytokines. In this context, ET, via the endothelin receptor type A (ET_A) activation, causes sustained vasoconstriction of the afferent arterioles that produces deleterious effects such as hyperfiltration, podocyte damage, proteinuria and, eventually, GFR decline. Therefore, endothelin receptor antagonists (ERAs) have been proposed as a therapeutic strategy to reduce proteinuria and slow the progression of kidney disease. Preclinical and clinical evidence has revealed that the administration of ERAs reduces kidney fibrosis, inflammation and proteinuria. Currently, the efficacy of many ERAs to treat kidney disease is being tested in randomized controlled trials; however, some of these, such as avosentan and atrasentan, were not commercialized due to the adverse events related to their use. Therefore, to take advantage of the protective properties of the ERAs, the use of ET_A receptor-specific antagonists and/or combining them with sodium-glucose cotransporter 2 inhibitors (SGLT2i) has been proposed to prevent oedemas, the main ERAs-related deleterious effect. The use of a dual angiotensin-II type 1/endothelin receptor blocker (sparsentan) is also being evaluated to treat kidney disease. Here, we reviewed the main ERAs developed and the preclinical and clinical evidence of their kidney-protective effects. Additionally, we provided an overview of new strategies that have been proposed to integrate ERAs in kidney disease treatment.

Endothelin receptor antagonists in kidney protection for diabetic kidney disease and beyond?

The burden of chronic kidney disease is increasing worldwide, largely due to the increasing global prevalence of diabetes mellitus and hypertension. While renin angiotensin system inhibitors and sodium-glucose cotransporter two inhibitors are the management cornerstone for reducing kidney and cardiovascular complications in patients with diabetic and non-diabetic kidney disease (DKD), they are partially effective and further treatments are needed to prevent the progression to kidney failure. Endothelin receptor antagonism represent a potential additional therapeutic option due to its beneficial effect on pathophysiological processes involved in progressive kidney disease including proteinuria, which are independently associated with progression of kidney disease. This review discusses the biological mechanisms of endothelin receptor antagonists (ERA) in kidney protection, the efficacy and safety of ERA in randomised controlled trials reporting on kidney outcomes, and its potential future use in both diabetic and non-DKDs.

Calcitriol attenuates vascular remodeling in association with alteration of ppET-1/ETBR/eNOS and ETAR expression in acute and chronic phases of kidney ischemia-reperfusion injury in mice

Kidney ischemia-reperfusion injury (IRI) causes acute kidney injury with increasing risk of maladaptive repair through endothelin-1 (ET-1)/endothelin type A receptor (ET_AR) signaling. Calcitriol shows renoprotection in kidney fibrosis, however, its effects on vasoactive substances expression and vascular remodeling following kidney IRI remain unclear. This research aimed to investigate Calcitriol's effects on preproendothelin-1 (ppET-1), ET_AR, endothelial nitric oxide synthase (eNOS) mRNA expression and vascular remodeling in acute and chronic phases of kidney IRI in mice. Twenty-five male Swiss mice were randomly divided into five groups (n = 5): SO (sham-operated), IR3 (3 day kidney IRI), IR12 (12 day kidney IRI), IRD3 (3 day kidney IRI + Calcitriol 0.5 µg/kg body weight (BW)/day), and IRD12 (12 day kidney IRI + Calcitriol 0.5 µg/kg BW/day). Ischemia-reperfusion injury groups underwent bilateral renal pedicles clamping for 30 min, then reperfusion. Kidneys were harvested for Sirius Red staining to observe interstitial fibrosis and vascular remodeling, polymerase chain reaction to quantify ppET-1, endothelin type B receptor (ET_BR), eNOS mRNA expression, and Western blotting to quantify ET_AR protein expression. Calcitriol treatment in both phases of kidney IRI showed lower serum creatinine and ET_AR protein expression, while higher eNOS and ET_BR mRNA expression than IRI-only groups. Furthermore, ppET-1 mRNA expression was higher in IRD3 than IR3, but lower in IRD12 than IR12. Calcitriol also prevented vascular remodeling as indicated by lower wall thickness and higher lumen/wall area ratio than IRI-only groups.