Endothelin in health and disease

Fetoplacental vasculature as a model to study human cardiovascular endocrine disruption

Increasing evidence has associated the exposure of endocrine-disrupting chemicals (EDCs) with the cardiovascular (CV) system. This exposure is particularly problematic in a sensitive window of development, pregnancy. Pregnancy exposome can affect the overall health of the pregnancy by dramatic changes in vascular physiology and endocrine activity, increasing maternal susceptibility. Moreover, fetoplacental vascular function is generally altered, increasing the risk of developing pregnancy complications (including cardiovascular diseases, CVD) and predisposing the foetus to adverse health risks later in life. Thus, our review summarizes the existing literature on exposures to EDCs during pregnancy and adverse maternal health outcomes, focusing on the human placenta, vein, and umbilical artery associated with pregnancy complications. The purpose of this review is to highlight the role of fetoplacental vasculature as a model for the study of human cardiovascular endocrine disruption. Therefore, we emphasize that the placenta, together with the umbilical arteries and veins, allows a better characterization of the pregnant woman's exposome. Consequently, it contributes to the protection of the mother and foetus against CV disorders in life.

Combination of hyperglycaemia and hyperlipidaemia induces endothelial dysfunction: Role of the endothelin and nitric oxide systems

Endothelial dysfunction (ED) is a key feature of diabetes and is a major cause of diabetic vasculopathy. Diabetic patients who also exhibit hyperlipidaemia suffer from accelerated vascular complications. While the deleterious effects of high glucose levels (HG) and hyperlipidaemia alone on ED are well established, the effects of combined hyperlipidaemia and HG have not been thoroughly studied. Therefore, the current study examines whether HG and hyperlipidaemia exert synergistic ED, and explores the mechanisms underlying this phenomenon. We applied multi‐disciplinary approaches including cultured HUVECs and HMEC‐1 as well as knockout mice CByJ.129S7(B6)‐Ldlrtm1Her/J (LDLR^−/−) to investigate the mechanisms underlying combined HG and hyperlipidaemia‐induced ED. Incremental doses of glucose in the presence or absence of OxLDL were added to HUVECs and HMEC‐1. After 5 days, the status of nitric oxide (NO) and endothelin (ET)‐1 systems as well as their signal transduction were assessed using Western blot, ELISA and immunoreactive staining. The effects of chronic combination of HG and hyperlipidaemia on endothelial integrity and function as well as alterations in circulatory NO and ET‐1 systems were examined in knockout mice LDLR^−/− and their wild‐type. HUVEC cells exposed to HG and OxLDL displayed enhanced ET‐1 production, more than HG or OxLDL when added alone. Overproduction of ET‐1 stems from up‐regulation of endothelin converting enzyme (ECE)‐1 as observed under these conditions. In contrast, combination of HG and OxLDL dramatically decreased both total endothelial NO synthase (eNOS) by 60%, and activated eNOS (peNOS) by 80%. Moreover, NRF2 decreased by 42% and its active form (pNRF2) by 56%, as compared to baseline. Likewise, ET_B levels decreased by 64% from baseline on endothelial cells. Furthermore, diabetic LDLR^−/− mice displayed a higher blood pressure, plasma triglycerides, cholesterol, ET‐1 and NO2/NO3 levels, when compared with normoglycemic LDLR^−/− and BALB mice. Combined hyperglycaemia and hyperlipidaemia activates the ET system and attenuates the nitric oxide system with the Nrf2 signalling pathway. These findings suggest that perturbations in these paracrine systems may contribute to ED.

Evaluation of Urinary Big Endothelin-1 in Feline Spontaneous CKD

Simple Summary

Chronic kidney disease is a common and progressive disease of elderly cats. It is a cause of pet suffering and owner expense. Biologic biomarkers for early diagnosis and for noninvasive evaluation of kidney damage are certainly useful in both research and clinical practice. In this study, we evaluated the biomarker big endotelin-1 in the urine of cats affected with chronic kidney disease. Big endothelin-1 is molecule linked to inflammation and pressure regulation, and it was not previously evaluated in nephropathic cats. We found that urinary big endothelin was increased in patients at late stage of the disease and in patients with proteinuria (a marker of kidney damage). Despite that, big endothelin 1 seemed not to be a useful biomarker for disease progression. According to results of this preliminary study, we suggest this biomarker for future research on feline kidney disease.

Abstract

The endothelin-1 (ET-1) system has been implicated in the development and progression of chronic kidney disease (CKD). No information on big ET-1 in feline urine is available. The purpose of this study was to evaluate if urinary big endothelin-1 (bigET-1) is associated with feline CKD. Sixty urine samples were prospectively collected from 13 healthy cats at risk of developing CKD and 22 cats with CKD of different International Renal Interest Society (IRIS) stages (1–4). Urinary bigET-1 was measured using a commercially available ELISA. BigET-1 normalized to urine creatinine (bigET-1:UC) was compared amongst stages and substages, as proposed by IRIS, and correlated with serum creatinine concentration, proteinuria and blood pressure. BigET-1:UC at the time of inclusion was compared between cats that remained stable and cats that progressed after 12 months. BigET-1:UC was significantly higher (p = 0.002) in cats at IRIS stages 3–4 (median: 21.9; range: 1.88–55.6), compared to all other stages, and in proteinuric (n = 8, median: 11.0; range: 0.00–46.4) compared with nonproteinuric cats (n = 38 median: 0.33; range: 0.00–55.6) (p = 0.029). BigET-1:UC was not associated with CKD progression. Urinary bigET-1 increased in advanced stages of CKD and in proteinuric patients, suggesting that ET-1 may be indicative of the severity of feline CKD.

Endothelin-1 promotes cardiomyocyte terminal differentiation in the developing heart via heightened DNA methylation

AIMS

Hypoxia is a major stress on fetal development and leads to induction of endothelin-1 (ET-1) expression. We tested the hypothesis that ET-1 stimulates the terminal differentiation of cardiomyocytes from mononucleate to binucleate in the developing heart.

METHODS AND RESULTS

Hypoxia (10.5% O2) treatment of pregnant rats from day 15 to day 21 resulted in a significant increase in prepro-ET-1 mRNA expression in fetal hearts. ET-1 ex vivo treatment of fetal rat cardiomyocytes increased percent binucleate cells and decreased Ki-67 expression, a marker for proliferation, under both control and hypoxic conditions. Hypoxia alone decreased Ki-67 expression and in conjunction with ET-1 treatment decreased cardiomyocyte size. PD145065, a non-selective ET-receptor antagonist, blocked the changes in binucleation and proliferation caused by ET-1. DNA methylation in fetal cardiomyocytes was significantly increased with ET-1 treatment, which was blocked by 5-aza-2'-deoxycytidine, a DNA methylation inhibitor. In addition, 5-aza-2'-deoxycytidine treatment abrogated the increase in binucleation and decrease in proliferation induced by ET-1.

CONCLUSIONS

Hypoxic stress and synthesis of ET-1 increases DNA methylation and promotes terminal differentiation of cardiomyocytes in the developing heart. This premature exit of the cell cycle may lead to a reduced cardiomyocyte endowment in the heart and have a negative impact on cardiac function.

Endothelin-1 stimulates proinflammatory cytokine expression in human periodontal ligament cells via mitogen-activated protein kinase pathway

BACKGROUND

Endothelin-1 (ET-1) is a 21-amino acid peptide with multifunctional regulation. Initial research indicated that ET-1 is related to the inflammatory pathogenesis of periodontitis and involved in the regulation of cytokines, but the mechanisms involved remain unclear. The primary aim of this study is to investigate how ET-1 affects proinflammatory cytokine expression in human periodontal ligament (hPDL) cells.

METHODS

hPDL cells were obtained from both healthy (H)- and periodontitis (P)-affected periodontal tissues. H-hPDL and P-hPDL cells were treated with ET-1 (1, 10, and 100 nM) for 12, 24, and 48 hours. The untreated cells served as a control. To confirm the specificity of the ET-1 effects, 100 nM of the specific endothelin A (ETA) receptor antagonist BQ123 and 100 nM of the specific ETB receptor antagonist BQ788, as negative control, were used. To examine the signaling pathways and molecular mechanisms involved in ET-1-mediated cytokine expression, H-hPDL and P-hPDL cells were pretreated with specific inhibitors for extracellular signal-regulated kinase (ERK1/2) (PD98059), c-Jun N-terminal kinase (SP600125), and p38 kinase (SB203580) for 1 hour before 100 nM ET-1 stimulation. Tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 messenger RNA (mRNA) and protein levels were evaluated by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.

RESULTS

ET-1 dose- and time-dependently induced the production of proinflammatory cytokines TNF-α, IL-1β, and IL-6 by H-hPDL and P-hPDL cells at both mRNA and protein levels. However, ETA and ETB receptor antagonists inhibited the stimulatory effects of ET-1 on inflammatory cytokine expression in H-hPDL and P-hPDL cells. Furthermore, inhibitors of the mitogen-activated protein kinases (MAPKs) significantly reduced ET-1-stimulated TNF-α, IL-1β, and IL-6 expression in H-hPDL and P-hPDL cells.

CONCLUSION

ET-1 may be involved in the inflammatory process of periodontitis, at least in part, by stimulating proinflammatory cytokine production via the MAPK pathway in hPDL cells.

Expression pattern of endothelin system components and localization of smooth muscle cells in the human pre-ovulatory follicle

BACKGROUND

Whether ovarian follicular rupture involves contractile activity or not has been debated for decades. Recently, study in the rodents has indicated that an endogenously produced potent vasoconstrictive peptide, endothelin-2 (EDN2), may induce follicular constriction immediately prior to ovulation. This study was aimed to systematically characterize the human ovarian endothelin system and localize smooth muscle cells to assess the possible involvement of contractile activity in human ovulation.

METHODS

This is a prospective experimental study. Study subjects were 20 women aged 20-38 years who underwent IVF owing to tubal or male factors. Expression patterns of messenger RNAs (mRNAs) for EDN1, EDN2, EDN3, endothelin-converting enzyme-1 (ECE1 and ECE2), endothelin receptor A (ET(A)) and ET(B) in the granulosa cells (GCs) and cumulus cells and endothelin peptide concentration in the pre-ovulatory follicles were measured at 36 h after hCG injection. In addition, localization of ovarian smooth muscle cells and endothelin receptor expression were determined in normal (non-IVF patient) ovaries.

RESULTS

Pre-ovulatory follicles express mRNA for EDN1 and EDN2, ECE1, ECE2, ET(A) and ET(B), but not EDN3, contain highly concentrated endothelin peptides (105.9 pg/ml) and are surrounded by theca externa that are made mostly of multicell layer non-vascular smooth muscle cells. ET(A) expression is localized in the smooth muscle cells of theca externa, theca interna and GC, whereas ET(B) expression is confined to theca interna.

CONCLUSIONS

Pre-ovulatory follicles contain highly concentrated endothelins and are surrounded by non-vascular smooth muscle cells that express endothelin receptor, suggesting involvement of endothelin-induced contractile action in ovulation in the human ovary.

Growth factors and folliculogenesis in polycystic ovary patients

Ovarian folliculogenesis is regulated by a fine balance between endocrine and intraovarian factors. In this review, we focus on the role of growth factors in physiological folliculogenesis and in polycystic ovaries. Recent evidence shows that the main systems implicated in polycystic ovary folliculogenesis are the growth hormone and insulin-like growth factor system, vascular endothelial growth factor, and the transforming growth factor-β family. Growth hormone and the insulin-like growth factor system could affect follicular development and oocyte maturation if their balance was altered, while vascular endothelial growth factor is implied in follicular dominance by providing an increasing vascular supply. The transforming growth factor-β family is composed of various molecules, which have different roles in cellular proliferation. Finally, a series of different factors seem to be involved in altered polycystic ovary follicular growth.