25Years of endothelin research: the next generation

Influence of Atherosclerosis-Associated Risk Factors on Expression of Endothelin Receptors in Advanced Atherosclerosis

Endothelin-1 (ET-1) levels are altered in atherosclerosis, while the roles of the endothelin receptors ETAR and ETBR during the pathogenesis of atherosclerosis remain unclear. Therefore, the focus of this study was to clarify how endothelin receptors are expressed in advanced human atherosclerotic plaques and how this is related to atherosclerotic risk factors. Ex vivo expression analysis was performed by quantitative real-time PCR (qRT-PCR) of 98 atherosclerotic plaques and controls that were obtained from adult patients undergoing vascular surgery. Correlation analyses of atherosclerosis-promoting factors were accomplished using a linear regression model. We found an overall reduced expression of ET receptors and smooth muscle actin (SMA), a marker of healthy vascular smooth muscle cells, in atherosclerotic plaques, whereas the levels of ET-1 and matrix metalloproteinase 2 (MMP-2), a marker of atherosclerosis progression, remained unchanged. Reduced expression was predominantly correlated with hypertension, which affects both receptors as well as SMA. Age, body mass index (BMI) and gender also correlated with either ETAR, ETBR or SMA expression in advanced plaques. In contrast, no effect of diabetes mellitus or smoking was found, indicating an ancillary effect of those risk factors. The results of our study indicate that endothelin receptor expression during the pathogenesis of atherosclerosis is predominantly correlated with hypertension.

Physical Exercise Protects Against Endothelial Dysfunction in Cardiovascular and Metabolic Diseases

Increasing evidence shows that endothelial cells play critical roles in maintaining vascular homeostasis, regulating vascular tone, inhibiting inflammatory response, suppressing lipid leakage, and preventing thrombosis. The damage or injury of endothelial cells induced by physical, chemical, and biological risk factors is a leading contributor to the development of mortal cardiovascular and cerebrovascular diseases. However, the underlying mechanism of endothelial injury remains to be elucidated. Notably, no drugs effectively targeting and mending injured vascular endothelial cells have been approved for clinical practice. There is an urgent need to understand pathways important for repairing injured vasculature that can be targeted with novel therapies. Exercise training-induced protection to endothelial injury has been well documented in clinical trials, and the underlying mechanism has been explored in animal models. This review mainly summarizes the protective effects of exercise on vascular endothelium and the recently identified potential therapeutic targets for endothelial dysfunction.

The Sixteenth International Conference on Endothelin (ET-16), Kobe, 2019

The Sixteenth International Conference on Endothelin (ET-16) was held September 22-25, 2019, in Kobe Port Oasis, Kobe, Japan, and co-chaired by Noriaki Emoto, MD, PhD, from Kobe Pharmaceutical University and Bambang Widyantoro, MD, PhD, from the University of Indonesia. As the sixteenth iteration of this biannual conference that has been held since 1988, ET-16 provided a platform for researchers of all generations from all parts of the world to present novel discoveries in the field of endothelin. ET-16 returned to Asia and to Kobe, Japan, after 6 years of alternating venues with North America and Europe, with over 100 participants attending, sharing, and discussing the newest findings on endothelin and endothelin receptor antagonists in science and medicine.

GPCR signaling and cardiac function

G protein-coupled receptors (GPCRs), such as β-adrenergic and angiotensin II receptors, located in the membranes of all three major cardiac cell types, i.e. myocytes, fibroblasts and endothelial cells, play crucial roles in regulating cardiac function and morphology. Their importance in cardiac physiology and disease is reflected by the fact that, collectively, they represent the direct targets of over a third of the currently approved cardiovascular drugs used in clinical practice. Over the past few decades, advances in elucidation of their structure, function and the signaling pathways they elicit, specifically in the heart, have led to identification of an increasing number of new molecular targets for heart disease therapy. Here, we review these signaling modalities employed by GPCRs known to be expressed in the cardiac myocyte membranes and to directly modulate cardiac contractility. We also highlight drugs and drug classes that directly target these GPCRs to modulate cardiac function, as well as molecules involved in cardiac GPCR signaling that have the potential of becoming novel drug targets for modulation of cardiac function in the future.

Endothelin XIII

Twenty-five years ago, a groundbreaking paper from Tsukuba University in Japan was published, identifying the sequence of the endothelin gene and peptide (Nature 332, 411-415, 1988). This work opened the way for the discovery of the endothelin receptors and the development of orally active endothelin receptor antagonists (ERAs). Today, ERAs are part of medical therapy of patients around the world for the treatment of pulmonary arterial hypertension. Since the discovery of endothelin, about 1000 papers per year have been published, with more than 27,000 articles available today. Many important and break-through findings presented in the endothelin conferences have been published in the conferences' proceedings. Endothelin XIII is the proceedings of the Thirteenth International Conference on Endothelin, held at Tokyo Campus of Tsukuba University, Japan, in September 2013. At the conference, the 25th anniversary of endothelin's discovery was celebrated and articles produced from data presented at the conference are compiled in this Special Issue of Life Sciences. Endothelin XIII includes more than fifty articles, including review articles by experts in the field and numerous original research articles. As the Editors of this special issue, we are proud to present Endothelin XIII and wish the field continued growth for the benefit of patients and for the advancement of biomedical science.