The X-ray crystal structure of human endothelin 1, a polypeptide hormone regulator of blood pressure

Targeting endothelin signaling in podocyte injury and diabetic nephropathy-diabetic kidney disease

Despite advances in diabetes management, there is an urgent need for novel therapeutic strategies since the current treatments remain insufficient in halting the progression of diabetic nephropathy-diabetic kidney disease (DN-DKD). This review is mainly addressed on the pivotal role of endothelin-1 in the pathophysiology of DN, with a specific focus on its effects on podocytes and the glomerular filtration barrier. Endothelin-1 promotes mesangial cell proliferation, sclerosis, and direct podocyte injury via the activation of endothelin type A and B receptors, that drive the progression of glomerulosclerosis in DN-DKD. Endothelin receptor antagonists, including drugs like atrasentan and sparsentan, have demonstrated nephroprotective effects in experimental models by reducing proteinuria and podocyte injury. The therapeutic potential to slow the progression of DN to end-stage kidney disease (ESKD) of these endothelin receptor antagonists in clinical practice is currently under evaluation. However, fluid retention and increased risk of heart failure associated with endothelin receptor antagonists need careful consideration. This review aims to provide an in-depth analysis of the pathophysiological role of endothelin and the emerging therapeutic implications of targeting this pathway in DN-DKD and discusses efficacy, safety, and the possibility of combining the new generation of endothelin receptor antagonists with the standard treatment of CKD and DN-DKD.

Endothelin and the Cardiovascular System: The Long Journey and Where We Are Going

Simple Summary

In this review, we describe the basic functions of endothelin and related molecules, including their receptors and enzymes. Furthermore, we discuss the important role of endothelin in several cardiovascular diseases, the relevant clinical evidence for targeting the endothelin pathway, and the scope of endothelin-targeting treatments in the future. We highlight the present uses of endothelin receptor antagonists and the advancements in the development of future treatment options, thereby providing an overview of endothelin research over the years and its future scope.

Abstract

Endothelin was first discovered more than 30 years ago as a potent vasoconstrictor. In subsequent years, three isoforms, two canonical receptors, and two converting enzymes were identified, and their basic functions were elucidated by numerous preclinical and clinical studies. Over the years, the endothelin system has been found to be critical in the pathogenesis of several cardiovascular diseases, including hypertension, pulmonary arterial hypertension, heart failure, and coronary artery disease. In this review, we summarize the current knowledge on endothelin and its role in cardiovascular diseases. Furthermore, we discuss how endothelin-targeting therapies, such as endothelin receptor antagonists, have been employed to treat cardiovascular diseases with varying degrees of success. Lastly, we provide a glimpse of what could be in store for endothelin-targeting treatment options for cardiovascular diseases in the future.

Endothelin: 30 Years From Discovery to Therapy

Discovered in 1987 as a potent endothelial cell-derived vasoconstrictor peptide, endothelin-1 (ET-1), the predominant member of the endothelin peptide family, is now recognized as a multifunctional peptide with cytokine-like activity contributing to almost all aspects of physiology and cell function. More than 30 000 scientific articles on endothelin were published over the past 3 decades, leading to the development and subsequent regulatory approval of a new class of therapeutics-the endothelin receptor antagonists (ERAs). This article reviews the history of the discovery of endothelin and its role in genetics, physiology, and disease. Here, we summarize the main clinical trials using ERAs and discuss the role of endothelin in cardiovascular diseases such as arterial hypertension, preecclampsia, coronary atherosclerosis, myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) caused by spontaneous coronary artery dissection (SCAD), Takotsubo syndrome, and heart failure. We also discuss how endothelins contributes to diabetic kidney disease and focal segmental glomerulosclerosis, pulmonary arterial hypertension, as well as cancer, immune disorders, and allograft rejection (which all involve ET_A autoantibodies), and neurological diseases. The application of ERAs, dual endothelin receptor/angiotensin receptor antagonists (DARAs), selective ET_B agonists, novel biologics such as receptor-targeting antibodies, or immunization against ET_A receptors holds the potential to slow the progression or even reverse chronic noncommunicable diseases. Future clinical studies will show whether targeting endothelin receptors can prevent or reduce disability from disease and improve clinical outcome, quality of life, and survival in patients.

Antibodies against Angiotensin II Type 1 and Endothelin A Receptors: Relevance and pathogenicity

Antibodies against two G-protein coupled receptors (GPCRs), angiotensin II type 1 receptor (AT1R) and endothelin A receptor (ETAR) are among a growing number of autoantibodies that are found to be associated with allograft dysfunction. AT1R antibodies (AT1Rabs) and ETAR antibodies (ETARabs) have been shown to activate their target receptors and affect signaling pathways. Multiple single center reports have shown an association between presence of these antibodies and acute or chronic rejection and graft loss in kidney, heart, liver, lung and composite tissue transplantations. However, the characteristics of patients that are most likely to develop adverse outcomes, the phenotypes associated with graft damage solely due to these antibodies, and the antibody titer required to cause dysfunction are areas that remain controversial. This review compiles existing knowledge on the effect of antibodies against GPCRs in other diseases in order to bridge the gap in knowledge within transplantation biology. Future areas for research are highlighted and include the need for functional assays and treatment protocols for transplant patients who present with AT1Rabs and ETARabs. Understanding how antibodies that activate GPCRs influence transplantation outcome will have direct clinical implications for preemptive evaluation of transplant candidates as well as the post-transplant care of organ recipients.

Associations of EDNRA and EDNRB Polymorphisms with Intracerebral Hemorrhage

OBJECTIVE

The most potent vasoconstrictor, endothelin-1 and its receptors, endothelin receptor A (EDNRA) and endothelin receptor B (EDNRB) are involved in hypertension. Hypertension is a major risk factor of intracerebral hemorrhage (ICH). Recent studies have demonstrated increased plasma endothelin-1 level in ICH patients and relationships between EDNRA and EDNRB genetic variants and ischemic stroke. The aim of the current study was to investigate whether EDNRA and EDNRB polymorphisms are associated with ICH by interacting with blood pressure levels.

METHODS

Five EDNRA and EDNRB polymorphisms were genotyped in this case-control study.

RESULTS

We identified that EDNRA rs5333 T allele might be a protective factor of ICH (adjusted odds ratio [OR] = 0.638, 95% CI: 0.417-0.977, P = 0.038), while EDNRB rs5351 A allele could be a risk factor of ICH (adjusted OR = 1.476, 95% CI: 1.042-2.089, P = 0.028). Moreover, we only found that the GG genotype of EDNRA rs5335 had higher diastolic blood pressure than the GC + CC genotypes in ICH patients (91.69 ± 18.77 vs. 84.71 ± 21.48, P = 0.004).

CONCLUSIONS

These findings support the important role of EDNRA and EDNRB polymorphisms in ICH, and suggest that they do not interact with blood pressure levels on altering ICH risk.