Endothelin Receptor Antagonists for Kidney Protection

Research trends and performance of endothelin A receptor antagonist in kidney care: a bibliometric analysis

BACKGROUND

Endothelin A receptor antagonists (ERAs) have emerged as pivotal therapeutic agents in managing pulmonary hypertension (PH) and various kidney disorders, including chronic kidney disease (CKD) and proteinuric glomerular diseases such as IgA nephropathy (IgAN) and focal segmental glomerulosclerosis (FSGS). Although initially developed for pulmonary applications, recent research has highlighted their renoprotective effects, expanding their role in nephrology. This study presents a comprehensive bibliometric analysis of global research trends, key contributors, and emerging applications of ERAs in kidney care over the past three decades.

METHODS

A bibliometric analysis was performed using the Science Citation Index Expanded database (1992-2023). Relevant kidney-related publications were identified through specific keyword searches. Author performance was assessed using the Y-index.

RESULTS

ERA-related research has shown significant growth, particularly in nephrology. The United States and the University of Groningen lead in publication volume and international collaborations, with H.J.L. Heerspink emerging as a key contributor. While PH remains the dominant research focus, nephrology applications are rapidly increasing, particularly in CKD, diabetic nephropathy (DN), and glomerular diseases. A major milestone was the accelerated FDA approval of sparsentan for IgAN in 2023, followed by full approval in 2024 based on confirmatory efficacy data. However, challenges such as fluid retention and cardiovascular risks remain, necessitating further investigation into optimized ERA therapies, including combination strategies with SGLT2 inhibitors.

CONCLUSIONS

The expanding role of ERAs in nephrology underscores their potential in treating proteinuric kidney diseases. Ongoing international collaborations are advancing research on ERA safety, efficacy, and novel therapeutic strategies, supporting their broader clinical application.

Slowing the progression of diabetic and non-diabetic kidney disease: A summary of the current evidence base for sodium-glucose co-transporter-2 inhibitors

The global prevalence of chronic kidney disease (CKD) is approximately 9%. CKD is predicted to become the fifth largest global cause of death by 2040. Moreover, CKD causes disability, diminished quality of life and poses a high cost to healthcare systems. Delaying the development and progression of CKD is therefore of the utmost importance. Several kidney-specific outcome trials on sodium-glucose co-transporter-2 inhibitors (SGLT-2s) have recently provided a paradigm shift in the treatment of people with CKD, with or without diabetes, as these agents have been shown to reduce the progression of CKD on top of maximally tolerated renin-angiotensin-aldosterone system (RAAS) blockade. The relative benefit and safety of SGLT-2is seems to be consistent across ethnicities, ages and frailty categories; however, this needs to be tested in dedicated clinical trials. Guidelines make clear recommendations for the prescription of SGLT-2is and RAAS inhibitors as standard of care for people with CKD. Their combination with other newer antidiabetic agents may provide further benefits by targeting different components of CKD mechanisms. Dedicated randomized controlled trials are needed to test whether combination with other agents could extend the use of SGLT2is and identify people in whom a combination of drugs may be most effective. Increased efforts to implement the guidelines on treatment with SGLT-2is for people with CKD are needed, particularly in those at the highest risk of adverse outcomes and without type 2 diabetes. Moreover, strategies to target the equitable use of SGLT-2is are needed.

Sparsentan is superior to losartan in the gddY mouse model of IgA nephropathy

BACKGROUND

The mechanism leading to the development of immunoglobulin A nephropathy (IgAN) remains to be completely understood. Endothelin-1 (ET-1) as well as angiotensin II (AngII) promote glomerular injury, tubulointerstitial inflammation and fibrosis leading to chronic kidney disease. Sparsentan, a dual endothelin angiotensin receptor antagonist, recently received accelerated approval in the USA for the reduction of proteinuria in adults with IgAN at high risk of disease progression. To elucidate the mechanisms by which sparsentan is efficacious in IgAN, we examined the effect of treatment in gddY mice, a spontaneous IgAN mouse model, versus the monoselective angiotensin II type 1 receptor (AT1R) antagonist, losartan, on the development of renal injury at doses resulting in similar blood pressure lowering.

METHODS

Four-week-old gddY mice were given control chow, chow containing sparsentan or drinking water containing losartan until 12 or 20 weeks old.

RESULTS

Remarkably, the albumin:creatine ratio (ACR) was attenuated more rapidly and to a greater extent in mice treated with sparsentan than those treated with losartan. The decrease in ACR from baseline after 4 weeks of treatment correlated with beneficial effects of sparsentan on glomerulosclerosis and protection of podocytes and glycocalyx after 16 weeks of treatment across treatment groups; thus, sparsentan treatment delayed development of renal injury to a greater extent than losartan. Expression of mRNA for ET-1, endothelin type A receptor and AT1R and proinflammatory genes was upregulated in 12-week-old gddY mice and was prevented by sparsentan and losartan to a comparable extent.

CONCLUSIONS

The results of this study, and in light of the results of the phase 3 PROTECT trial, provide a novel perspective and understanding of the mechanisms by which sparsentan has a beneficial renoprotective effect against IgAN compared with AT1R antagonism alone.

Add-on astragalus in type 2 diabetes and chronic kidney disease: A multi-center, assessor-blind, randomized controlled trial

BACKGROUND

Diabetes leads to chronic kidney disease (CKD) and kidney failure, requiring dialysis or transplantation. Astragalus, a common herbal medicine and US pharmacopeia-registered food ingredient, is shown kidney protective by retrospective and preclinical data but with limited long-term prospective clinical evidence. This trial aimed to assess the effectiveness of astragalus on kidney function decline in macroalbuminuric diabetic CKD patients.

METHODS

This randomized, assessor-blind, standard care-controlled, multi-center clinical trial randomly assigned 118 patients with estimated glomerular filtration rate (eGFR) of 30-90 ml/min/1.73m2 and urinary albumin-to-creatinine ratio (UACR) of 300-5000 mg/g from 7 public outpatient clinics and the community in Hong Kong between July 2018 and April 2022 to add-on oral astragalus granules (15 gs of raw herbs daily equivalent) or to continue standard care alone as control for 48 weeks. Primary outcomes were the slope of change of eGFR (used for sample size calculation) and UACR of the intention-to-treat population. Secondary outcomes included endpoint blood pressures, biochemistry, biomarkers, concomitant drug change and adverse events. (ClinicalTrials.gov: NCT03535935) RESULTS: During the 48-week period, the estimated difference in the slope of eGFR decline was 4.6 ml/min/1.73m2 per year (95 %CI: 1.5 to 7.6, p = 0.003) slower with astragalus. For UACR, the estimated inter-group proportional difference in the slope of change was insignificant (1.14, 95 %CI: 0.85 to 1.52, p = 0.392). 117 adverse events from 31 astragalus-treated patients and 41 standard care-controlled patients were documented. The 48-week endpoint systolic blood pressure was 7.9 mmHg lower (95 %CI: -12.9 to -2.8, p = 0.003) in the astragalus-treated patients. 113 (96 %) and 107 (91 %) patients had post-randomization and endpoint primary outcome measures, respectively.

CONCLUSION

In patients with type 2 diabetes, stage 2 to 3 CKD and macroalbuminuria, add-on astragalus for 48 weeks further stabilized kidney function on top of standard care.

Endothelin System in Hypertension and Chronic Kidney Disease

ET (endothelin) is a powerful vasoconstrictor 21-amino acid peptide present in many tissues, which exerts many physiological functions across the body and participates as a mediator in many pathological conditions. ETs exert their effects through ETA and ETB receptors, which can be blocked by selective receptor antagonists. ETs were shown to play important roles among others, in systemic hypertension, particularly when resistant or difficult to control, and in pulmonary hypertension, atherosclerosis, cardiac hypertrophy, subarachnoid hemorrhage, chronic kidney disease, diabetic cardiovascular disease, scleroderma, some cancers, etc. To date, ET antagonists are only approved for the treatment of primary pulmonary hypertension and recently for IgA nephropathy and used in the treatment of digital ulcers in scleroderma. However, they may soon be approved for the treatment of patients with resistant hypertension and different types of nephropathy. Here, the role of ETs is reviewed with a special emphasis on participation in and treatment of hypertension and chronic kidney disease.

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.

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.

Treatment and practical considerations of diabetic kidney disease

Diabetic kidney disease (DKD) is a complication of diabetes that can lead to kidney failure. Over the years, several drugs have been developed to combat this disease. In the early 90s, angiotensin blockade (ACEi and ARBs) was introduced, which revolutionized the treatment of DKD. In recent years, newer drugs such as sodium-glucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide-1 (GLP-1) receptor agonists, endothelin antagonists, and mineralocorticoid receptor antagonists (MRA) have shown great promise in reducing albuminuria and protecting the kidneys. These drugs are being used in combination with lifestyle modifications, patient education, and risk factor modification to effectively manage DKD. In this review, we will explore the latest pharmacological options, their efficacy, and their potential to revolutionize the management of this debilitating disease.

Add-on Rehmannia-6-Based Chinese Medicine in Type 2 Diabetes and CKD: A Multicenter Randomized Controlled Trial

BACKGROUND

Diabetes is the leading cause of CKD and kidney failure. We assessed the real-world effectiveness of Rehmannia-6-based Chinese medicine treatment, the most used Chinese medicine formulation, on the change in eGFR and albuminuria in patients with diabetes and CKD with severely increased albuminuria.

METHODS

In this randomized, assessor-blind, standard care-controlled, parallel, multicenter trial, 148 adult patients from outpatient clinics with type 2 diabetes, an eGFR of 30-90 ml/min per 1.73 m 2 , and a urine albumin-to-creatinine ratio (UACR) of 300-5000 mg/g were randomized 1:1 to a 48-week add-on protocolized Chinese medicine treatment program (using Rehmannia-6-based formulations in the granule form taken orally) or standard care alone. Primary outcomes were the slope of change in eGFR and UACR between baseline and end point (48 weeks after randomization) in the intention-to-treat population. Secondary outcomes included safety and the change in biochemistry, biomarkers, and concomitant drug use.

RESULTS

The mean age, eGFR, and UACR were 65 years, 56.7 ml/min per 1.73 m 2 , and 753 mg/g, respectively. Ninety-five percent ( n =141) of end point primary outcome measures were retrievable. For eGFR, the estimated slope of change was -2.0 (95% confidence interval [CI], -0.1 to -3.9) and -4.7 (95% CI, -2.9 to -6.5) ml/min per 1.73 m 2 in participants treated with add-on Chinese medicine or standard care alone, resulting in a 2.7 ml/min per 1.73 m 2 per year (95% CI, 0.1 to 5.3; P = 0.04) less decline with Chinese medicine. For UACR, the estimated proportion in the slope of change was 0.88 (95% CI, 0.75 to 1.02) and 0.99 (95% CI, 0.85 to 1.14) in participants treated with add-on Chinese medicine or standard care alone, respectively. The intergroup proportional difference (0.89, 11% slower increment in add-on Chinese medicine, 95% CI, 0.72 to 1.10; P = 0.28) did not reach statistical significance. Eighty-five adverse events were recorded from 50 participants (add-on Chinese medicine versus control: 22 [31%] versus 28 [36%]).

CONCLUSIONS

Rehmannia-6-based Chinese medicine treatment stabilized eGFR on top of standard care alone after 48 weeks in patients with type 2 diabetes, stage 2-3 CKD, and severely increased albuminuria.

CLINICAL TRIAL REGISTRY

Semi-individualized Chinese Medicine Treatment as an Adjuvant Management for Diabetic Nephropathy (SCHEMATIC), NCT02488252 .

Early diabetic kidney disease: Focus on the glycocalyx

The incidence of diabetic kidney disease (DKD) is sharply increasing worldwide. Microalbuminuria is the primary clinical marker used to identify DKD, and its initiating step in diabetes is glomerular endothelial cell dysfunction, particularly glycocalyx impairment. The glycocalyx found on the surface of glomerular endothelial cells, is a dynamic hydrated layer structure composed of pro-teoglycans, glycoproteins, and some adsorbed soluble components. It reinforces the negative charge barrier, transduces the shear stress, and mediates the interaction of blood corpuscles and podocytes with endothelial cells. In the high-glucose environment of diabetes, excessive reactive oxygen species and proinflammatory cytokines can damage the endothelial glycocalyx (EG) both directly and indirectly, which induces the production of microalbuminuria. Further research is required to elucidate the role of the podocyte glycocalyx, which may, together with endothelial cells, form a line of defense against albumin filtration. Interestingly, recent research has confirmed that the negative charge barrier function of the glycocalyx found in the glomerular basement membrane and its repulsion effect on albumin is limited. Therefore, to improve the early diagnosis and treatment of DKD, the potential mechanisms of EG degradation must be analyzed and more responsive and controllable targets must be explored. The content of this review will provide insights for future research.

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.

SGLT2 Inhibitors in Diabetic and Non-Diabetic Chronic Kidney Disease

Results from recent randomized controlled trials on inhibitors of the sodium-glucose cotransporter 2 (SGLT2) have determined a paradigm shift in the treatment of patients with type 2 diabetes mellitus. These agents have been shown not only to ameliorate metabolic control, but also to independently protect from cardiovascular events and to reduce the progression of chronic kidney disease (CKD) in these patients. The magnitude of the nephroprotective effect observed in these studies is likely to make SGLT2 inhibitors the most impactful drug class for the treatment of diabetic patients with CKD since the discovery of renin-angiotensin system inhibitors. Even more surprisingly, SGLT2 inhibitors have also been shown to slow CKD progression in non-diabetic individuals with varying degrees of proteinuria, suggesting that activation of SGLT2 is involved in the pathogenesis of CKD independent of its etiology. As indications continue to expand, it is still unclear whether the observed benefits of SGLT2 inhibitors may extend to CKD patients at lower risk of progression and if their association with other agents may confer additional protection.

Circadian clocks of the kidney: function, mechanism, and regulation

An intrinsic cellular circadian clock is located in nearly every cell of the body. The peripheral circadian clocks within the cells of the kidney contribute to the regulation of a variety of renal processes. In this review, we summarize what is currently known regarding the function, mechanism, and regulation of kidney clocks. Additionally, the effect of extrarenal physiological processes, such as endocrine and neuronal signals, on kidney function is also reviewed. Circadian rhythms in renal function are an integral part of kidney physiology, underscoring the importance of considering time of day as a key biological variable. The field of circadian renal physiology is of tremendous relevance, but with limited physiological and mechanistic information on the kidney clocks this is an area in need of extensive investigation.