Enhanced expressions of endothelin-converting enzyme and endothelin receptors in human colonic tissues of Crohn's disease

Endothelin-Receptor Antagonists beyond Pulmonary Arterial Hypertension: Cancer and Fibrosis

The endothelin axis and in particular the two endothelin receptors, ETA and ETB, are targets for therapeutic intervention in human diseases. Endothelin-receptor antagonists are in clinical use to treat pulmonary arterial hypertension and have been under clinical investigation for the treatment of several other diseases, such as systemic hypertension, cancer, vasospasm, and fibrogenic diseases. In this Perspective, we review the molecules that have been evaluated in human clinical trials for the treatment of pulmonary arterial hypertension, as well as other cardiovascular diseases, cancer, and fibrosis. We will also discuss the therapeutic consequences of receptor selectivity with regard to ETA-selective, ETB-selective, or dual ETA/ETB antagonists. We will also consider which chemical characteristics are relevant to clinical use and the properties of molecules necessary for efficacy in treating diseases against which known molecules displayed suboptimal efficacy.

Endothelins implicated in referred mechanical hyperalgesia associated with colitis induced by TNBS in miceThis article is one of a selection of papers published in the two-part special issue entitled 20 Years of Endothelin Research

This study evaluated the contribution of endothelins to changes in sensitivity to mechanical stimulation of the lower abdomen and hind paw associated with 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. The frequency of withdrawal responses to 10 consecutive applications of von Frey probes to the lower abdomen (0.07 g) or hind paw (0.4 g) was assessed in male BALB/c mice before and after intracolonic TNBS injection (0.5 mg in 100 µL of 35% ethanol). TNBS (0.5 mg) induced referred mechanical hyperalgesia in the abdomen (response frequencies at 24 h: saline 11.0% ± 3.1%, TNBS 48.0% ± 6.9%) and hind paw (frequencies at 24 h: saline 12.5% ± 4.7%, TNBS 47.1% ± 7.1%) lasting up to 72 and 48 h, respectively. Mice receiving 1.0 or 1.5 mg TNBS assumed hunch-backed postures and became immobile during abdominal mechanical stimulation, suggestive of excessive ongoing pain. Atrasentan (ETA receptor antagonist; 10 and 30 mg/kg, i.v.) given 24 h after TNBS abolished hind paw and abdominal mechanical hyperalgesia for 2–3 h. A-192621 (ETB receptor antagonist; 20 mg/kg, i.v.) attenuated abdominal mechanical hyperalgesia at the 3 h time point only. Thus, endothelins contribute importantly to abdominal and hind paw referred mechanical hyperalgesia during TNBS-induced colitis mainly through ETA receptor-signaled mechanisms.