endothelin-1 and epigallocatechin-gallate

Healthy vascular endothelial cells regulate vascular tone and permeability, prevent vessel wall inflammation, enhance thromboresistance, and contribute to general vascular health. Furthermore, they perform important functions including the production of vasoactive substances such as nitric oxide (NO) and endothelium-derived hyperpolarizing factors, as well as the regulation of smooth muscle cell functions. Conversely, vascular endothelial dysfunction leads to atherosclerosis, thereby enhancing the risk of stroke, myocardial infarction, and other cardiovascular diseases (CVDs). Observational studies and randomized trials showed that green tea intake was inversely related to CVD risk. Furthermore, evidence indicates that epigallocatechin gallate (EGCG) found in green tea might exert a preventive effect against CVDs. EGCG acts as an antioxidant, inducing NO release and reducing endothelin-1 production in endothelial cells. EGCG enhances the bioavailability of normal NO by reducing levels of the endogenous NO inhibitor asymmetric dimethylarginine. Furthermore, it inhibits the enhanced expression of adhesion molecules such as vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 and attenuates monocyte adhesion. In addition, EGCG prevents enhanced oxidative stress through the Nrf2/HO-1 pathway. These effects indicate that it might prevent the production of reactive oxygen species, inhibit inflammation, and reduce endothelial cell apoptosis during the initial stages of atherosclerosis. The current review summarizes recent research in this area and discusses novel findings regarding the protective effect of EGCG on endothelial dysfunction and CVDs in general.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Apoptosis; Atherosclerosis; Catechin; Cell Adhesion Molecules; Endothelial Cells; Endothelin-1; Endothelium, Vascular; Humans; Nitric Oxide; Oxidative Stress

Vascular endothelial cell (EC) dysfunction strongly induces development of cardiovascular and cerebrovascular diseases. Epidemiologic studies demonstrated a preventative effect of dietary polyphenols toward cardiovascular disease. In studies using cultured vascular ECs, polyphenols were recognized to regulate nitric oxide and endothelin-1 (ET-1) production. Furthermore, epigallocatechin-3-gallate inhibited the expression of adhesion molecules by a signaling pathway that is similar to that of high-density lipoprotein and involves induction of Ca(2+)/calmodulin-dependent kinase II, liver kinase B, and phosphatidylinositol 3-kinase expression. The effects of polyphenols on ECs include antioxidant activity and enhancement of the expression of several protective proteins, including endothelial nitric oxide synthase and paraoxonase 1. However, the observed effects of dietary polyphenols in vitro do not always translate to an in vivo setting. As such, there are many questions concerning their physiological mode of action. In this review, we discuss research on the effect of dietary polyphenols on cardiovascular disease and their protective effect on EC dysfunction.

Topics: Administration, Oral; Animals; Apigenin; Aryldialkylphosphatase; Cardiovascular Diseases; Catechin; Diet; Disease Models, Animal; Endothelial Cells; Endothelin-1; Humans; Lipoproteins, HDL; Nitric Oxide; Nitric Oxide Synthase Type III; Polyphenols; Signal Transduction; U937 Cells

Topics: Catechin; Endothelin-1; Forkhead Box Protein O1; Forkhead Transcription Factors; Humans; Oncogene Protein v-akt; Phosphorylation; Tea; Vasodilator Agents

Dietary flavonoids may improve endothelial function and ultimately lead to beneficial cardiovascular effects.. The objective was to assess whether pure dietary flavonoids can modulate nitric oxide and endothelin-1 production and thereby improve endothelial function.. A randomized, placebo-controlled, crossover trial in 12 healthy men was conducted to compare the acute effects of the oral administration of 200 mg quercetin, (-)-epicatechin, or epigallocatechin gallate on nitric oxide, endothelin-1, and oxidative stress after nitric oxide production was assessed via the measurement of plasma S-nitrosothiols and plasma and urinary nitrite and nitrate concentrations. The effects on oxidative stress were assessed by measuring plasma and urinary F(2)-isoprostanes. Plasma and urinary concentrations of quercetin, (-)-epicatechin, and epigallocatechin gallate were measured to establish the absorption of these flavonoids.. Relative to water (control), quercetin and (-)-epicatechin resulted in a significant increase in plasma S-nitrosothiols, plasma nitrite, and urinary nitrate concentrations (P < 0.05), but not in plasma nitrate or urinary nitrite. Epigallocatechin gallate did not alter any of the measures of nitric oxide production. Quercetin and (-)-epicatechin resulted in a significant reduction in plasma endothelin-1 concentration (P < 0.05), but only quercetin significantly decreased the urinary endothelin-1 concentration. None of the 3 treatments significantly changed plasma or urinary F(2)-isoprostane concentrations. Significant increases in the circulating concentrations of the 3 flavonoids were observed (P < 0.05) after the corresponding treatment.. Dietary flavonoids, such as quercetin and (-)-epicatechin, can augment nitric oxide status and reduce endothelin-1 concentrations and may thereby improve endothelial function.

Topics: Adult; Catechin; Cross-Over Studies; Diet; Endothelin-1; Endothelium, Vascular; F2-Isoprostanes; Flavonoids; Humans; Intestinal Absorption; Male; Nitrates; Nitric Oxide; Nitrites; Oxidative Stress; Quercetin; S-Nitrosothiols

We investigated the mechanism underlying anti-tumor necrosis factor-α (TNF-α) effects of epigallocatechin-3-gallate (EGCG) in human aortic endothelial cells.. Tumor necrosis factor receptor 1 (TNFR1) was assessed by Western blot analysis. Cytosolic Ca2+ was measured using Fluo-4 AM. A disintegrin and metalloprotease 10 (ADAM10) was localized by immunofluorescence staining.. EGCG caused ectodomain shedding of TNFR1 within 30 min and attenuated TNF-α-induced endothelin-1 (ET-1) expression. EGCG-induced TNFR1 ectodomain shedding was prevented by BAPTA-AM (intracellular Ca2+ chelator), but not by the absence of extracellular Ca2+. In physiologic extracellular Ca2+ concentration, EGCG markedly increased cytosolic Ca2+. Even in the absence of extracellular Ca2+, EGCG raised cytosolic Ca2+, though less potently. siRNA depletion of ADAM10 prevented EGCG-induced ectodomain shedding of TNFR1 and also diminished the inhibitory effect of EGCG on TNF-α-induced ET-1 expression. EGCG caused translocation of ADAM10 to the plasma membrane, and this effect was prevented by BAPTA-AM. Besides extracellular Ca2+ influx, release of intracellular stored Ca2+ caused ADAM10-dependent ectodomain shedding of TNFR1.. EGCG decreases the responsiveness of cells to TNF-α by causing ADAM10-dependent ectodomain shedding of TNFR1. This effect was attributed to its property to increase cytosolic Ca2+ through both extracellular Ca2+ influx and release of stored Ca2+.

Topics: ADAM10 Protein; Blotting, Western; Calcium; Catechin; Cell Line; Cell Membrane; Egtazic Acid; Endothelial Cells; Endothelin-1; Gene Expression; Humans; Microscopy, Fluorescence; Receptors, Tumor Necrosis Factor, Type I; RNA Interference; RNA, Small Interfering; Tumor Necrosis Factor-alpha

There is a growing body of evidence suggesting that epigallocatechin gallate (EGCG), a major catechin isolated from green tea, has several beneficial effects, such as anti-oxidant and anti-inflammatory activities. However, whether treatment with EGCG can suppress the endothelin-1 (ET-1)-induced contraction in carotid arteries from type 2 diabetic rats is unknown, especially at the chronic stage of the disease. We hypothesized that long-term treatment with EGCG would attenuate ET-1-induced contractions in type 2 diabetic arteries.. Otsuka Long-Evans Tokushima fatty (OLETF) rats (43 weeks old) were treated with EGCG (200 mg/kg/day for 2 months, p.o.), and the responsiveness to ET-1, phenylephrine (PE), acetylcholine (ACh) and sodium nitroprusside (SNP) was measured in common carotid artery (CA) from EGCG-treated and -untreated OLETF rats and control Long-Evans Tokushima Otsuka (LETO) rats.. In OLETF rats, EGCG attenuated responsiveness to ET-1 in CA compared to untreated groups. However, EGCG did not alter PE-induced contractions in CA from OLETF rats. In endothelium-denuded arteries, EGCG did not affect ET-1-induced contractions in either the OLETF or LETO group. Acetylcholine-induced relaxation was increased by EGCG treatment in CA from the OLETF group. The expressions of ET receptors, endothelial nitric oxide synthase, superoxide dismutases, and gp91(phox) [an NAD(P)H oxidase component] in CA were not altered by EGCG treatment in either group.. Our data suggest that, within the timescale investigated here, EGCG attenuates ET-1-induced contractions in CA from type 2 diabetic rats, and one of the mechanisms may involve normalizing endothelial function.

Topics: Acetylcholine; Animals; Carotid Arteries; Catechin; Chronic Disease; Diabetes Mellitus, Experimental; Endothelin-1; In Vitro Techniques; Male; NADPH Oxidases; Nitric Oxide Synthase Type III; Nitroprusside; Phenylephrine; Rats, Inbred OLETF; Receptors, Endothelin; Superoxide Dismutase; Vasoconstriction; Vasodilation

Endoplasmic reticulum stress (ER stress)-associated thioredoxin-interacting protein (TXNIP) and NOD-like receptor pyrin domain containing-3 (NLRP3) signaling is a key event in the endothelial dysfunction. It induces the IL-1β production and thus accounts for inflammation and cell death. Quercetin, luteolin and epigallocatechin gallate (EGCG) are flavonoids with beneficial effects on cardiovascular functions, and we wondered whether these flavonoids protect endothelial functions against ER stress-associated impairments. Palmitate stimulation evoked oxidative stress and then induced TXNIP and NLRP3 inflammasome activation in the endothelial cells. Quercetin, luteolin and EGCG reduced reactive oxygen species production and inhibited TXNIP and NLRP3 inflammasome activation, lead to the downregulation of IL-1β expression. Meanwhile, these agents protected cells from apoptosis by restoration of mitochondrial membrane potential (Δψm) and inhibition of caspase-3 activity. PA stimulation induced inflammation accompanied by the loss of NO production in endothelial cells, but these alterations were reversed by treatment with quercetin, luteolin and EGCG. Co-treatment with AMPK inhibitor compound C diminished the beneficial effects of these flavonoids, suggesting the involvement of AMPK. In conclusion, quercetin, luteolin and EGCG inhibited ER stress-associated TXNIP and NLRP3 inflammasome activation, and thereby protected endothelial cells from inflammatory and apoptotic damage.

Topics: AMP-Activated Protein Kinases; Apoptosis; Carrier Proteins; Catechin; Cell Line; Endoplasmic Reticulum Stress; Endothelial Cells; Endothelin-1; Gene Expression; Human Umbilical Vein Endothelial Cells; Humans; Inflammasomes; Inflammation; Luteolin; NLR Family, Pyrin Domain-Containing 3 Protein; Oxidative Stress; Palmitic Acid; Protein Kinase Inhibitors; Quercetin

Epigallocatechin gallate (EGCG), a green tea polyphenol, promotes vasodilation by phosphatidylinositol 3-kinase-dependent activation of Akt and endothelial nitric oxide synthase to stimulate production of nitric oxide. Reduction in endothelin-1 (ET-1) synthesis may also increase bioavailability of nitric oxide. We hypothesized that the phosphatidylinositol 3-kinase-dependent transcription factor FOXO1 may mediate effects of EGCG to regulate expression of ET-1 in endothelial cells. EGCG treatment (10 microm, 8 h) of human aortic endothelial cells reduced expression of ET-1 mRNA, protein, and ET-1 secretion. We identified a putative FOXO binding domain in the human ET-1 promoter 51 bp upstream from the transcription start site. Trans-activation of a human ET-1 (hET-1) promoter luciferase reporter was enhanced by coexpression of a constitutively nuclear FOXO1 mutant, whereas expression of a mutant FOXO1 with disrupted DNA binding domain did not trans-activate the hET-1 promoter. Disrupting the hET-1 putative FOXO binding domain by site-directed mutagenesis ablated promoter activity in response to overexpression of wild-type FOXO1. EGCG stimulated time-dependent phosphorylation of Akt (S(473)), FOXO1 (at Akt phosphorylation site T(24)), and AMP-activated protein kinase alpha (AMPK alpha) (T(172)). EGCG-induced nuclear exclusion of FOXO1, FOXO1 binding to the hET-1 promoter, and reduction of ET-1 expression was partially inhibited by the AMPK inhibitor Compound C. Basal ET-1 protein expression was enhanced by short interfering RNA knock-down of Akt and reduced by short interfering RNA knock-down of FOXO1 or adenovirus-mediated expression of dominant-negative Foxo1. We conclude that EGCG decreases ET-1 expression and secretion from endothelial cells, in part, via Akt- and AMPK-stimulated FOXO1 regulation of the ET-1 promoter. These findings may be relevant to beneficial cardiovascular actions of green tea.

Topics: AMP-Activated Protein Kinases; Animals; Binding Sites; Catechin; Cattle; Cells, Cultured; Down-Regulation; Endothelial Cells; Endothelin-1; Flavonoids; Forkhead Box Protein O1; Forkhead Transcription Factors; Gene Expression; Humans; Mice; NIH 3T3 Cells; Oncogene Protein v-akt; Phenols; Polyphenols; Promoter Regions, Genetic; Tea

We previously showed that endothelin-1 (ET-1) stimulates the synthesis of interleukin-6 (IL-6), a potent bone resorptive agent, in osteoblast-like MC3T3-E1 cells, and that protein kinase C (PKC)-dependent p44/p42 mitogen-activated protein (MAP) kinase plays a part in the IL-6 synthesis. In the present study, we investigated the effect of (-)-epigallocatechin gallate (EGCG), one of the major flavonoids containing in green tea, on ET-1-induced IL-6 synthesis in osteoblasts and the underlying mechanism. EGCG significantly reduced the synthesis of IL-6 stimulated by ET-1 in MC3T3-E1 cells as well primary cultured mouse osteoblasts. SB203580, a specific inhibitor of p38 MAP kinase, but not SP600125, a specific SAPK/JNK inhibitor, suppressed ET-1-stimulated IL-6 synthesis. ET-1-induced phosphorylation of p38 MAP kinase was not affected by EGCG. On the other hand, EGCG suppressed the phosphorylation of p44/p42 MAP kinase induced by ET-1. Both the IL-6 synthesis and the phosphorylation of p44/p42 MAP kinase stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA), a direct activator of PKC, were markedly suppressed by EGCG. The phosphorylation of MEK1/2 and Raf-1 induced by ET-1 or TPA were also inhibited by EGCG. These results strongly suggest that EGCG inhibits ET-1-stimulated synthesis of IL-6 via suppression of p44/p42 MAP kinase pathway in osteoblasts, and the inhibitory effect is exerted at a point between PKC and Raf-1 in the ET-1 signaling cascade.

Topics: Animals; Anthracenes; Catechin; Cells, Cultured; Endothelin-1; Enzyme Activation; Flavonoids; Imidazoles; Interleukin-6; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Osteoblasts; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Protein Kinase C; Proto-Oncogene Proteins c-raf; Pyridines; Tetradecanoylphorbol Acetate

The green tea polyphenol, epigallocatechin-3-gallate (EGCG), has been shown to prevent cancer; however, a precise mechanism responsible for tumor growth inhibition has not yet been clearly described. The endothelin (ET) A receptor (ET(A)R)/ET-1 autocrine pathway is overexpressed in ovarian carcinoma and triggers tumor growth, neoangiogenesis, and invasion. These latter tumor-promoting effects are mediated through the activation of cyclooxygenase (COX)-1- and COX-2-dependent pathways by ET-1. In the present study, pretreatment of HEY and OVCA 433 ovarian carcinoma cell lines with green tea and EGCG inhibited ET-1/ET(A)R expression, ET(A)R-mediated COX-1/2 mRNA expression, and COX-2 promoter activity. These effects were associated with a significant reduction in the COX-1/2-derived prostaglandin E2 (PGE2) production. These results provide a novel insight into the mechanism by which EGCG, by affecting ET(A)R-dependent COX-1/2 pathways may inhibit ovarian tumors suggesting that EGCG may be useful in preventing and treating ovarian carcinoma in which activation of ET(A)R by ET-1 plays a critical role in tumor growth and progression.

Topics: Antineoplastic Agents; Catechin; Cell Line, Tumor; Cyclooxygenase Inhibitors; Dinoprostone; Endothelin A Receptor Antagonists; Endothelin-1; Female; Humans; Ovarian Neoplasms; Promoter Regions, Genetic; RNA, Messenger; Tea

The polyphenol epigallocatechin-3-gallate (EGCG), the principal mediator of the green tea, has been known to possess antitumor effect. The endothelin A receptor (ET(A)R)/endothelin-1 (ET-1) axis is overexpressed in ovarian carcinoma representing a novel therapeutic target. In this study, we examined the green tea and EGCG effects on two ovarian carcinoma cell lines, HEY and OVCA 433. EGCG inhibited ovarian cancer cell growth and induced apoptosis that was associated with a decrease in Bcl-X(L) expression and activation of caspase-3. Treatment with green tea or EGCG inhibited ET(A)R and ET-1 expression and reduced the basal and ET-1-induced cell proliferation and invasion. The EGCG-induced inhibitory effects were associated with a decrease of ET(A)R-dependent activation of the p42/p44 and p38 mitogen-activated protein kinases and phosphatidylinositol 3-kinase pathway. Remarkably, EGCG treatment resulted in a lowering of basal and ET-1-induced angiogenesis and invasiveness mediators, such as vascular endothelial growth factor and tumor proteinase activation. Finally, in HEY ovarian carcinoma xenografts, tumor growth was significantly inhibited by oral administration of green tea. This effect was associated with a reduction in ET-1, ET(A)R, and vascular endothelial growth factor expression, microvessel density, and proliferation index. These results provide a novel insight into the mechanism by which EGCG, affecting multiple ET(A)R-dependent pathways, may inhibit ovarian carcinoma growth, suggesting that EGCG may be useful in preventing and treating ovarian carcinoma in which ET(A)R activation by ET-1 plays a critical role in tumor growth and progression.

Topics: Animals; Anticarcinogenic Agents; Apoptosis; bcl-X Protein; Caspase 3; Caspases; Catechin; Cell Proliferation; Endothelin-1; Enzyme Activation; Female; Humans; Mice; Mice, Nude; Mitogen-Activated Protein Kinases; Neoplasm Invasiveness; Ovarian Neoplasms; Phosphatidylinositol 3-Kinases; Receptor, Endothelin A; Signal Transduction; Tea; Transplantation, Heterologous; Urokinase-Type Plasminogen Activator; Vascular Endothelial Growth Factor A