MDM2-Mediated Ubiquitination of RXRß Contributes to Mitochondrial Damage and Related Inflammation in Atherosclerosis.

A novel function of retinoid X receptor beta (RXRß) in endothelial cells has been reported by us during the formation of atherosclerosis. Here, we extended the study to explore the cellular mechanisms of RXRß protein stability regulation. In this study, we discovered that murine double minute-2 (MDM2) acts as an E3 ubiquitin ligase to target RXRß for degradation. The result showed that MDM2 directly interacted with and regulated RXRß protein stability. MDM2 promoted RXRß poly-ubiquitination and degradation by proteasomes. Moreover, mutated MDM2 RING domain (C464A) or treatment with an MDM2 inhibitor targeting the RING domain of MDM2 lost the ability of MDM2 to regulate RXRß protein expression and ubiquitination. Furthermore, treatment with MDM2 inhibitor alleviated oxidized low-density lipoprotein-induced mitochondrial damage, activation of TLR9/NF-κB and NLRP3/caspase-1 pathway and production of pro-inflammatory cytokines in endothelial cells. However, all these beneficial effects were reduced by the transfection of RXRß siRNA. Moreover, pharmacological inhibition of MDM2 attenuated the development of atherosclerosis and reversed mitochondrial damage and related inflammation in the atherosclerotic process in LDLr-/- mice, along with the increased RXRß protein expression in the aorta. Therefore, our study uncovers a previously unknown ubiquitination pathway and suggests MDM2-mediated RXRß ubiquitination as a new therapeutic target in atherosclerosis.

2, 3, 4', 5-tetrahydroxystilbene-2-0-ß-d Glycoside Attenuates Age- and Diet-Associated Non-Alcoholic Steatohepatitis and Atherosclerosis in LDL Receptor Knockout Mice and Its Possible Mechanisms.

The compound, 2,3,5,4'-tetrahydroxystilbene-2-O-ß-d-glucoside (TSG), a primary bioactive polyphenolic component of Polygonum multiflorum exerts numerous pharmacological activities. However, its protective effect against non-alcoholic steatohepatitis (NASH), in the context of metabolic syndrome, remains poorly understood. The aim of the present study is to evaluate the effects of TSG treatment on middle-aged (12-mo-old) male LDLr-/- mice, which were fed a high fat diet for 12 weeks to induce metabolic syndrome and NASH. At the end of the experiment, the blood samples of mice were collected for determination of metabolic parameters. Liver and aorta tissues were collected for analysis, such as histology, immunofluorescence, hepatic lipid content, real-time PCR, and western blot. Our data show that TSG treatment improved the different aspects of NASH (steatosis, inflammation, and fibrosis) and atherosclerosis, as well as some of the metabolic basal characteristics. These modulatory effects of TSG are mediated, at least in part, through regulating key regulators of lipid metabolism (SREBP1c, PPARα and their target genes, ABCG5 and CYP7A1), inflammation (CD68, TNF-α, IL-6 and ICAM), fibrosis (α-SMA and TNFß) and oxidative stress (NADPH-oxidase 2/4, CYP2E1 and antioxidant enzymes). These results suggest that TSG may be a promising candidate for preventing and treating the progression of NASH.

Economic evaluation of 5-HT3 receptor antagonists in combination with dexamethasone for the prevention of 'overall' nausea and vomiting following highly emetogenic chemotherapy in Chinese adult patients.

Background Two pivotal Phase III trials compared the efficacy of palonosetron, ondansetron and granisetron, combined with dexamethasone, for the prevention of nausea and vomiting following highly emetogenic chemotherapy. However, an economic evaluation of these three regimens in the real-world setting of Chinese adult patients has not been determined. Objectives To estimate, from the perspective of the Chinese healthcare system, which of these frequently used strategies consisting of 0.25 mg palonosetron (0.25P), 16 mg ondansetron (Onda), and 3 mg granisetron (Gran), is the most cost-effective option in patients following highly emetogenic chemotherapy. Methods A Markov decision-analytic model was developed. The health and economic outcomes of the three strategies; 0.25P, Onda, and Gran were investigated. The clinical and utility data were taken from published studies. The cost data were calculated according to current local Chinese practices. Sensitivity analyses were performed to determine the impact of uncertainty regarding the results. Results The base-case analysis showed that the 0.25P strategy yielded maximum health benefits compared with the other two strategies. However, the probabilistic sensitivity analysis demonstrated that the Gran strategy was the most cost-effective approach when the willingness-to-pay threshold was not more than US$22,515/quality-adjusted life year. Moreover, palonosetron is not cost-effective in preventing 'overall' nausea and vomiting following highly emetogenic chemotherapy in Chinese patients. Conclusions Our analysis suggests that, compared with palonosetron and ondansetron, 3 mg granisetron may be a cost-effective treatment option in the current Chinese healthcare setting.

Salusin-ß induces smooth muscle cell proliferation by regulating cyclins D1 and E expression through MAPKs signaling pathways.

Despite the clear mitogenic effect of salusin-ß on vascular smooth muscle cells (VSMCs), which contributes to its proatherosclerotic effects, additional studies are needed to explore its underlying mechanisms. The aim of this study was to investigate the mechanism of salusin-ß's effects on VSMCs cell cycle regulation and the possible signal pathways. Salusin-ß accelerated the G1/S phase transition in VSMCs and increased the expression levels of cyclins D1 and E. Silencing either cyclin D1 or cyclin E gene inhibited salusin-ß-induced VSMCs proliferation, cell cycle progression, phosphorylation of the Rb protein, and dissociation of the E2F-Rb complex. Importantly, expression of cyclin E was also induced by cyclin D1. Next, we found that salusin-ß increased the protein expressions of activator protein-1 (AP-1) subunits c-Jun and c-Fos, and enhanced binding of AP-1 to the promoter region of cyclin D1. In addition, inhibition of AP-1 activity could lead to significant suppression of salusin-ß-induced cyclin D1 expression. Furthermore, MPAKs pathways were found to mediate salusin-ß-induced VSMCs proliferation, cyclin D1, cyclin E, c-Jun, and c-Fos expression. These results suggest that salusin-ß promotes cell cycle progression of VSMCs by upregulating the cyclin D1 and cyclin E, in an AP-1-dependent manner through mitogen-activated protein kinases signaling pathways.

The effect of 2,3,4',5-tetrahydroxystilbene-2-O-ß-D-glucoside on pressure overload-induced cardiac remodeling in rats and its possible mechanism.

The aim of the present study was to investigate the effects of 2,3,4',5-tetrahydroxystilbene-2-O-beta-D-glucoside, an active component extracted from Polygonum multiflorum, on pressure overload-induced cardiac remodeling in rats. A rat model with cardiac remodeling was induced by abdominal aortic banding. 2,3,4',5-Tetrahydroxystilbene-2-O-beta-D-glucoside (30, 60, 120 mg/kg/day) was administered 3 days after abdominal aortic banding and continued for 30 days. The abdominal aortic banding-treated rats had significantly elevated blood pressure, left ventricular hypertrophy, and myocardial fibrosis. Left ventricular hypertrophy was characterized by an increase in the ratios of the heart and left ventricular weights to body weight, and increased myocyte cross-sectional areas, hypertrophic ventricular septum, and left ventricular posterior wall. The accumulation of myocardial interstitial perivascular collagen and elevated cardiac hydroxyproline content indicated myocardial fibrosis. The pathological changes above were attenuated by 2,3,4',5-tetrahydroxystilbene-2-O-beta-D-glucoside. Additionally, it markedly reduced collagen I and III expressions and regulated matrix metalloproteinase-2,9 and inhibitors of metalloproteinase expressions, as markers of myocardial fibrosis. Furthermore, we explored the underlying mechanisms for such effects of 2,3,4',5-tetrahydroxystilbene-2-O-beta-D-glucoside. The results showed that it significantly reduced myocardium angiotensin II, enhanced the activities of superoxide dismutase and glutathione peroxidase in serum and myocardial tissue, as well as inhibited protein expression of transforming growth factor-ß1 and phosphorylation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase in the myocardial tissue. Our results suggest that 2,3,4',5-tetrahydroxystilbene-2-O-beta-D-glucoside could prevent cardiac remodeling induced by pressure overload in rats. The underlying mechanisms may be related to a decreasing angiotensin II level, an antioxidant effect of the tested compound, suppression of transforming growth factor-ß1 expression, and inhibition of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase activation.

Promoting reverse cholesterol transport contributes to the amelioration of atherosclerosis by paeoniflorin.

Reverse cholesterol transport (RCT) offers a practical approach to mitigating atherosclerosis. Paeoniflorin, a monoterpenoid glycoside found in plants of the Paeoniaceae family, has shown various effects on cardiovascular and liver diseases. Nevertheless, its impact on atherosclerosis in vivo remains poorly understood. The objective of this study is to examine the effect of paeoniflorin on atherosclerosis using apolipoprotein E-deficient (ApoE-/-) mice and explore the underlying mechanisms, with a specific focus on its modulation of RCT. ApoE-/- mice were continuously administered paeoniflorin by gavage for three months. We assessed lipid parameters in serum and examined pathological changes and gene expressions related to RCT pathways in the aorta, liver, and intestine. In an in vitro study, we utilized RAW264.7 macrophages to investigate the inhibitory effect of paeoniflorin on foam cell formation and its potential to promote RCT. The results revealed that paeoniflorin reduced atherosclerosis, alleviated hyperlipidemia, and mitigated hepatic steatosis. Paeoniflorin may promote RCT by stimulating cholesterol efflux from macrophages via the liver X receptor alpha pathway, enhancing serum high-density lipoprotein cholesterol and apolipoprotein A-I levels, and regulating key genes in hepatic and intestinal RCT. Additionally, treatment ApoE-/- mice with paeoniflorin suppressed the expression of inflammation-related genes, including CD68, tumor necrosis factor alpha, and monocyte chemoattractant protein-1, and mitigated oxidative stress in both the aorta and liver. Our results indicated that paeoniflorin has the potential to be a more effective and safer treatment for atherosclerosis, thanks to its promotion of RCT and its anti-inflammatory and anti-oxidative effects.

2,3,4',5-tetrahydroxystilbene-2-O-ß-D-glucoside inhibits proliferation of vascular smooth muscle cells: involvement of NO/cGMP/PKG pathway.

The proliferation of vascular smooth muscle cells (VSMCs) induced by injury to the intima of arteries is an important etiologic factor in vascular proliferative disorders such as atherosclerosis and restenosis. 2,3,4',5-Tetrahydroxystilbene-2-O-ß-D-glucoside (TSG), an active component extracted from Polygonum multiflorum, has been found to have an antiatherosclerotic effect. The aim of this study was to investigate the effects of TSG on platelet derived growth factor (PDGF)-BB induced VSMCs proliferation and to explore the possible mechanisms of such effects. Pretreatment of VSMCs with TSG significantly inhibited PDGF-BB-induced cell proliferation in a concentration-dependent but not time-dependent manner. In addition, flow cytometry analysis of the DNA content revealed blocking of the PDGF-BB-inducible cell cycle progression by TSG. On the contrary, an inhibitory effect of TSG on VSMCs proliferation and expression of cell cycle regulators were markedly attenuated by addition of an nitric oxide (NO) synthase inhibitor, a soluble guanylate cyclase inhibitor and a cyclic GMP (cGMP)-dependent protein kinase (PKG) inhibitor: N(G)-nitro-L-arginine methyl ester (L-NAME), 1H-[1,2,4] oxadiazolo [4,3-α] quinoxalin-1-one (ODQ) and KT5823, respectively. It was also demonstrated that TSG enhanced NO and cGMP formation through up-regulating endothelial NO synthase expression in VSMCs. The findings indicate that TSG inhibited VSMCs proliferation induced by PDGF-BB may involve the NO/cGMP/PKG signal pathway.

Activating PGC-1α-mediated signaling cascades in the aorta contributes to the amelioration of vascular senescence and atherosclerosis by 2,3,4',5-tetrahydroxystilbene-2-O-ß-d-glycoside.

BACKGROUND: 2,3,4',5-tetrahydroxystilbene-2-O-ß-d-glycoside (TSG), the main active polyphenolic component of Polygonum multiflorum, possesses many pharmacological activities. Its anti-aging effect influences a variety of tissues with diverse mechanisms. However, the effectiveness and exact mechanisms of TSG against vascular senescence in atherosclerosis remain unclear. The present study is aimed to investigate the effects of TSG against vascular senescence in atherosclerosis both in vivo and in vitro, and the possible underlying mechanisms focusing on aortic peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)-mediated signaling cascades which have never been studied. METHODS: In vivo, 12-mo-old male LDLr-/- mice were randomly separated into control, high-fat diet (HFD), and TSG -treatment groups. At the end of the 12 weeks, the blood samples and aorta tissues of mice were collected for further analysis. In vitro, to mimic the condition of endothelial senescence in hyperlipidemic mice, human aortic endothelial cells (HAECs) were incubated with oxidized low-density lipoprotein (ox-LDL) to induce senescence. RESULTS: TSG administration improved lipid profiles, ameliorated HFD-exacerbated vascular senescence and atherosclerosis. The protective effect of TSG via inhibiting telomere malfunction, oxidative stress, and mitochondrial damage was found both in vivo and in vitro. Notably, TSG administration increased aortic PGC-1α mRNA and protein expression along with the regulation of its targeted genes TERT, NRF1, TFAM, Mn-SOD, and catalase. Further, by using PGC-1α siRNA in ox-LDL-treated HAECs, it is proved that TSG reduced endothelial senescence, telomere malfunction, oxidative stress, and mitochondrial damage at least partly through activating the PGC-1α pathway. CONCLUSIONS: These results provide new evidence for TSG in the treatment of atherosclerosis and the activation of aortic PGC-1α is involved in its beneficial effects.

2,3,4',5-Tetrahydroxystilbene-2-O-ß-d-glucoside inhibits platelet-derived growth factor-induced proliferation of vascular smooth muscle cells by regulating the cell cycle.

1. 2,3,4',5-Tetrahydroxystilbene-2-O-ß-d-glucoside (TSG) has been shown to have an anti-atherosclerotic effect. Vascular smooth muscle cell (VSMC) proliferation contributes to the pathobiology of atherosclerosis. The aim of the present study was to investigate the effects of TSG on platelet-derived growth factor (PDGF)-BB-induced VSMC proliferation and to explore the molecular mechanisms underlying the effects. 2. Cultured rat VSMC were pretreated with TSG (l-50 µmol/L) for 1 h, followed by exposure to PDGF-BB (10 ng/mL) for 24 h, after which cell proliferation and cell cycle stages were examined. The expression of protein cell cycle regulators, including retinoblastoma (Rb), cyclin D1/E, cyclin-dependent kinase (CDK) 2/4, CDK inhibitors p21 and p27 and proliferative cell nuclear antigen (PCNA), was examined. Activation of extracellular signal-regulated kinase (ERK) 1/2 was evaluated to elucidate the possible upstream mechanism by which TSG affects cell cycle regulators. 3. The results showed that TSG dose-dependently inhibited PDGF-BB-induced VSMC proliferation, possibly by blocking the progression of the cell cycle from the G(1) to S phase. In addition, TSG significantly inhibited PDGF-BB-induced phosphorylation of Rb and the expression of cyclin D1, CDK4, cyclin E, CDK2 and PCNA. In addition, TSG suppressed PDGF-BB-induced downregulation of p27 and upregulation of p21, as well as PDGF-BB-induced activation of ERK1/2. 4. Together, the findings of the present study provide the first evidence that TSG can inhibit PDGF-BB-stimulated VSMC proliferation via cell cycle arrest in association with modulation of the expression of cell cycle regulators, which may be mediated, at least in part, by suppression of ERK1/2 activation.

Naringenin alleviates nonalcoholic steatohepatitis in middle-aged Apoe-/-mice: role of SIRT1.

BACKGROUND: Naringenin is naturally isolated from citrus fruits possessing many pharmacological activities. However, little is known about the effect of naringenin on nonalcoholic steatohepatitis (NASH) in the model of metabolic syndrome. PURPOSE: The present study is aimed to investigate the effect of naringenin on NASH in 12-mo-old male ApoE-/- mice and its possible underlying mechanism. METHODS: In vivo, 12-mo-old male ApoE-/- mice were administrated with naringenin by intragastric gavage for 12 weeks. At the end of experiment, the blood samples and liver tissues were collected. Metabolic parameters in serum, levels of triglyceride, cholesterol and hydroxyproline, activities of antioxidant enzymes, and content of inflammatory cytokines (TNF-α and IL-6) in liver were examined by corresponding assay kits. Pathological changes in liver were observed by hematoxylin-eosin, oil red O, masson's trichrome, picro-sirius red and senescence ß-galactosidase staining. Dihydroethidium was used for detection of reactive oxygen species (ROS). In vitro, AML-12 cells were treated with oleic acid in the presence or absence of naringenin for 24 h. Transfection of SIRT1 siRNA was also conducted in vitro. Lipid accumulation, cellular ROS generation, malondialdehyde content, antioxidant enzyme activities and secretion levels of TNF-α and IL-6 were examined. Both in vivo and in vitro, gene expressions were detected by real-time PCR or western blot. RESULTS: Naringenin administration improved metabolic parameters, suppressed hepatic steatosis, regulated expression of genes involved in lipid metabolism (FASN, SCD1, PPARα and CPT1α), reduced hepatic fibrosis and cell senescence, inhibited hepatic inflammation as evidenced by the decreased macrophage recruitment and content of TNF-α and IL-6, and reduced hepatic oxidative stress by suppressing ROS generation and normalizing activities of antioxidant enzymes. Notably, naringenin administration increased hepatic SIRT1 protein expression and activity along with the increased deacetylation of liver kinase B1 (LKB1), PGC1α and NF-κB. In vitro study, the benefits of naringenin on lipid accumulation, oxidative stress and inflammation were diminished by SIRT1 siRNA transfection. CONCLUSIONS: These results indicate that naringenin administration may be a potential curative therapy for NASH treatment and the activation of hepatic SIRT1-mediated signaling cascades is involved in its beneficial effects.

MDM2 contributes to oxidized low-density lipoprotein-induced inflammation through modulation of mitochondrial damage in endothelial cells.

BACKGROUND AND AIMS: Murine double minute-2 (MDM2) has been poorly studied in cardiovascular diseases. The aim of the present study was to determine the biological role of MDM2 in inflammation activation and mitochondrial damage in human aortic endothelial cells (HAECs) stimulated with oxidized low-density lipoprotein (ox-LDL). METHODS: The expression of MDM2 in the aortas of atherosclerotic mice was determined. An adenoviral vector for MDM2 overexpression and siRNA for MDM2 downregulation were constructed and used to transfect HAECs. The functional changes in HAECs stimulated by ox-LDL were observed. RESULTS: The protein expression of MDM2 was increased in atherosclerotic mice and ox-LDL-treated HAECs. In addition, ox-LDL-induced mRNA expression and secretion of TNF-α, IL-6 and IL-1ß were significantly decreased by MDM2 downregulation and increased by MDM2 overexpression, and activation of NF-κB and caspase-1 was involved in the activity of MDM2. The ox-LDL-induced mitochondrial damage, indicated as increase in mitochondrial ROS production, decrease in mitochondrial membrane potential and elevation of mitochondrial DNA release, was significantly reversed by MDM2 downregulation and worsened by MDM2 overexpression. The ox-LDL-induced activation of TLR9/NF-κB and NLRP3/caspase-1 pathway was inhibited by MDM2 downregulation and worsened by MDM2 overexpression. The aggravation caused by MDM2 overexpression was abolished by mito-TEMPO. Treatment with mito-TEMPO significantly reduced the increase in mRNA expression and secretion of TNF-α, IL-6 and IL-1ß induced by MDM2 overexpression in ox-LDL treated HAECs. CONCLUSIONS: These findings suggest that MDM2 contributes to ox-LDL-induced inflammation via regulating mitochondrial damage.

Modulation of SIRT1-mediated signaling cascades in the liver contributes to the amelioration of nonalcoholic steatohepatitis in high fat fed middle-aged LDL receptor knockout mice by dihydromyricetin.

Dihydromyricetin (DMY) is the most abundant flavonoid in Ampelopsis grossedentata possessing many pharmacological activities. But less is known about its protective effect against nonalcoholic steatohepatitis (NASH) in the context of metabolic syndrome. The present study is aimed to evaluate the pharmacological effects of DMY on NASH induced by feeding a high fat diet to 12-mo-old male LDLr-/- mice for 12 weeks and its molecular mode of action. At the end of the experiment, the blood samples and liver tissues of mice were collected for analysis. The results showed that DMY treatment improved the steatosis, inflammation and fibrosis which are three main aspects of NASH and some of the metabolic basal characteristics. The underlying mechanisms include regulating key regulators of lipid metabolism, oxidative stress, inflammation and fibrosis. Notably, DMY treatment increased hepatic sirtuin 1 (SIRT1) activity and protein expression. DMY also enhanced deacetylation of liver kinase B1 (LKB1) and nuclear transcription factor kappa B (NF-kB). Furthermore, in cultured hepatocyte cells, the benefits of DMY on lipid accumulation, oxidative stress and inflammation as well as the above related genes were abrogated in hepatocytes transfected with SIRT1 siRNA. These results suggest that modulation of SIRT1-mediated signaling cascades contributes to the amelioration of NASH by DMY and DMY may serve as a potentialtherapeuticcandidate for human NASH.

Effects of 2,3,4',5-tetrahydroxystilbene 2-O-beta-D-glucoside on vascular endothelial dysfunction in atherogenic-diet rats.

2,3,4',5-Tetrahydroxystilbene 2- O-beta- D-glucoside (TSG), an active component extracted from Polygonum multiflorum, has been found to have an anti-atherosclerotic effect. The aim of this study was to investigate whether the TSG could prevent the development of atherosclerosis through influencing endothelial function in atherogenic-diet rats and to explore the possible mechanisms. Vascular endothelial dysfunction was assessed using isolated aortic ring preparation, transmission electron microscopy of the aorta, and levels of nitrate/nitrite (NOx) in serum and aorta. Endothelial nitric oxide (NO) synthase (eNOS) and inducible NO synthase (iNOS) mRNA and protein expression were also measured. After 12 weeks treatment, TSG improved acetylcholine-induced endothelium-dependent relaxation, prevented intimal remodeling, inhibited the decreased NOx content in serum and aorta in atherogenic-diet rats. Furthermore, the observed decreased eNOS mRNA and protein expression and increased iNOS mRNA and protein expression in atherogenic-diet rats were attenuated by TSG treatment. These results suggest that TSG could restore vascular endothelial function, which may be related to its ability to prevent changes of eNOS and iNOS expression, leading to preservation of NO bioactivity.

Polydatin attenuates atherosclerosis in apolipoprotein E-deficient mice: Role of reverse cholesterol transport.

BACKGROUND: Polydatin has been recently shown to possess extensive cardiovascular pharmacological activities. However, its protective effect against atherosclerosis in vivo remains poorly understood. The aim of the present study was to evaluate the potential effects of polydatin on high fat diet (HFD)-induced atherosclerosis using ApoE-/- mice, and explore the underlying mechanisms involved, especially focusing on reverse cholesterol transport (RCT) regulation. METHODS: after 12 weeks treatment, serum samples, mouse aorta, liver, peritoneal macrophages were collected to determine lipid profiles, atherosclerotic lesions, hepatic steatosis, foam cell formation and expression of related molecules. RAW264.7 macrophages were used to study cholesterol efflux. RESULTS: Polydatin improved serum lipid profiles, attenuated atherosclerosis and hepatic steatosis. Furthermore, polydatin may facilitate RCT by stimulating cholesterol efflux through ATP-binding cassette transporters (ABC) A1, ABCG1 and scavenger receptor class B type I (SR-BI) in macrophages, increasing serum levels of high density lipoprotein and apolipoprotein A-I, promoting of SR-BI-mediated cholesterol uptake of liver, increasing secretion of cholesterol into bile by ABCG5/ABCG8 and improving cholesterol metabolism by CYP7A1 pathway. Polydatin also regulated the protein expressions of hepatic fatty acid synthase and peroxisome proliferator-activated receptor-α. Additionally, polydatin reduced hepatic and aortic reactive oxygen species generation, normalized activities of antioxidant enzymes and increased protein expressions of NADPH-oxidase (NOX) 2 and NOX4 in liver. Polydatin also prevented hepatic and aortic inflammation as evidenced by the reduced macrophage infiltration and mRNA expressions of tumor necrosis factor-α and interleukin-6 in both aorta and liver. CONCLUSION: These findings indicated that polydatin can inhibit atherosclerosis through enhancement of overall RCT. In addition, anti-oxidative and anti-inflammatory effect of polydatin may also contribute to its inhibitory effects on atherosclerosis.

Astragaloside IV improved intracellular calcium handling in hypoxia-reoxygenated cardiomyocytes via the sarcoplasmic reticulum Ca-ATPase.

Although astragaloside IV, a saponin isolated from Astragalus membranaceus, has been shown to protect the myocardium against ischemia/reperfusion injury, its effect on the status of sarcoplasmic reticulum (SR) Ca2+ transport in the injured myocardium remains largely unknown. In this study, we investigated whether in cultured cardiomyocytes subjected to hypoxia and reoxygenation (H/R) administration of astragaloside IV during H/R attenuates the myocardial cell injury and prevents changes in Ca2+ handling activities and gene expression of SR Ca2+ pump. Cultured cardiomyocytes from neonatal rats were exposed to 6 h of hypoxia followed by 3 h of reoxygenation. Myocyte injury was determined by the release of cardiac troponin I in supernatant. Astragaloside IV significantly inhibited cardiac troponin I release after H/R in a dose-dependent manner. The diastolic [Ca2+]i measured with Fura-2/AM was significantly increased after reoxygenation. Astragaloside IV prevented the rise of diastolic [Ca2+]i and the depression of caffeine-induced Ca2+ transients caused by H/R. Furthermore, the observed depressions in SR Ca2+-ATPase activity as well as the mRNA and protein expression of SR Ca2+-ATPase in hypoxic-reoxygenated cardiomyocytes were attenuated by astragaloside IV treatment. These results suggest that the beneficial effect of astragaloside IV in H/R-induced injury may be related to normalization of SR Ca2+ pump expression and, thus, may prevent the depression in SR Ca2+ handling.

Cardioprotective effects of Astragali Radix against isoproterenol-induced myocardial injury in rats and its possible mechanism.

The purpose of the present study was to investigate the effects of the Chinese medical herb Astragali Radix on myocardial injury in vivo and its possible mechanisms. Myocardial injury in rats was induced by the subcutaneous injection of a high dose of isoproterenol for 10 days, and the therapeutic effects of Astragali Radix were observed. Cardiac hemodynamics, heart coefficient and marker enzymes in serum showed that Astragali Radix prevented isoproterenol-induced myocardial damage. Astragali Radix also improved the antioxidant status by decreasing the lipid peroxidative product malondialdehyde and increasing the activity of the antioxidant enzyme superoxide dismutase. The observed depressions in sarcoplasmic reticulum Ca2+-ATPase mRNA and protein expression as well as Ser(16)-phosphorylated phospholamban protein expression in isoproterenol-treated rats were attenuated by Astragali Radix treatment. Moreover, treatment with Astragali Radix showed higher myocardial cAMP content compared with the isoproterenol-alone group. These results suggest that the antioxidant property and partial prevention of changes in protein and gene expression of cardiac sarcoplasmic reticulum Ca2+ regulatory proteins which may be mediated through the cAMP pathway could help to explain the beneficial effects of Astragali Radix on myocardial injury in vivo.

Dihydromyricetin ameliorates foam cell formation via LXRα-ABCA1/ABCG1-dependent cholesterol efflux in macrophages.

As the most abundant flavonoid in Ampelopsis grossedentata, the protective effects of dihydromyricetin on atherosclerosis have been well established, yet the detailed mechanisms are not fully understood. The aim of the present study was to examine the effect of dihydromyricetin on lipid accumulation and the underlying molecular mechanisms in macrophages and ApoE-/- mice. Incubation with dihydromyricetin significantly attenuated oxidized low-density lipoprotein (ox-LDL)-mediated cholesterol and lipid accumulation in THP-1-derived macrophages, which was due to increased cholesterol efflux. In addition, dihydromyricetin increased mRNA and protein expressions of ATP-binding cassette transporter A1 (ABCA1) and ABCG1 but had no effect on the mRNA and protein expressions of SR-A, CD36, or SR-BI involved in cholesterol homeostasis. Furthermore, the upregulation of ABCA1 and ABCG1 by dihydromyricetin depended on liver X receptor α (LXRα), as evidenced by an increase in the nuclear level of LXRα and its prevention of the expression of ABCA1 and ABCG1 after inhibition of LXRα activity by knockdown of LXRα expression with small interfering RNA (siRNA). Accordingly, dihydromyricetin-mediated suppression of cholesterol and lipid accumulation in macrophages was also abrogated by LXRα siRNA. Moreover, the lesion size of atherosclerosis was smaller in dihydromyricetin-treated ApoE-/- mice compared with the vehicle-treated mice, and the protein expression of CD36, SR-A, ABCA1, ABCG1 and LXRα in aortas was modulated similar to that observed in THP-1-derived macrophages. These data suggest that promotion of LXRα-ABCA1/ABCG1-dependent cholesterol efflux is crucial event in suppression of lipid accumulation by dihydromyricetin in the transformation of macrophage foam cells.

Modification of alterations in cardiac function and sarcoplasmic reticulum by astragaloside IV in myocardial injury in vivo.

Astragaloside IV, the primary pure saponin isolated from Astragalus membranaceus has been found to have potent cardioprotective effects. In this study, we aim to investigate if the beneficial effects of astragaloside IV on cardiac function are associated with improvement in sarcoplasmic reticulum Ca(2+)-pump function in myocardial injury in vivo. Myocardial injury in rats was induced by subcutaneous injection of a high dose of isoproterenol, and the therapeutic effect of astragaloside IV was observed. Isoproterenol-treated rats showed widespread subendocardial necrosis, a rise in serum lactate dehydrogenase and creatine kinase, formation of lipid oxide product malondialdehyde and inhibition of left ventricular diastolic and systolic function, which suggested severe myocardial injury and acute heart failure. Moreover, sarcoplasmic reticulum Ca(2+)-uptake ability and Ca(2+)-ATPase (SERCA2a) activity were significantly reduced. And the level of SERCA2a mRNA and protein expression was also markedly decreased, associated with a decrease in Ser(16)-phosphorylated phospholamban protein expression, while total phospholamban level was unchanged in the isoproterenol-treated group compared with controls. However, these biochemical and hemodynamic changes in the acute failing hearts were prevented by treatment of isoproterenol-induced rats with astragaloside IV. Likewise, the observed reductions in sarcoplasmic reticulum Ca(2+)-pump function as well as in SERCA2a mRNA and protein levels and the phosphorylation level of phospholamban in the injured hearts were attenuated by astragaloside IV treatment. These results suggest that the beneficial effect of astragaloside IV on isoproterenol-induced myocardial injury may be due to its ability to prevent changes of SERCA2a and Ser(16)-phosphorylated phospholamban protein expression and, thus, may prevent the depression in sarcoplasmic reticulum Ca(2+) transport and improve cardiac function.

Dihydromyricetin ameliorates atherosclerosis in LDL receptor deficient mice.

BACKGROUND AND AIMS: Dihydromyricetin, the most abundant flavonoid in Ampelopsis grossedentata, exerts numerous pharmacological activities, including anti-inflammatory, antioxidant, hepatoprotective, and lipid regulatory activities; however, its protective effect against atherosclerosis remains poorly understood. The aim of the present study was to evaluate the effects of dihydromyricetin on high fat diet (HFD)-induced atherosclerosis using LDL receptor deficient (LDLr-/-) mice. METHODS: Blood samples were collected for determination of serum lipid profiles, oxidized LDL (ox-LDL) and pro-inflammatory cytokines. Histology, hepatic lipid content, quantification of atherosclerosis, assessment of oxidative stress and inflammation were performed on liver and aorta samples by molecular biology methods. The effects of dihydromyricetin on ox-LDL-induced human umbilical vein endothelial cells (HUVECs) dysfunction and foam cell formation were further studied. RESULTS: (1) Dihydromyricetin ameliorated hyperlipidemia, reduced serum ox-LDL, IL-6 and TNF-α levels in HFD-fed LDLr-/- mice. Moreover, (2) dihydromyricetin suppressed hepatic lipid accumulation and increased protein expressions of PPARα, LXRα and ABCA1. (3) It inhibited atherosclerotic lesion formation and favoured features of plaque stability. (4) Dihydromyricetin prevented hepatic and aortic inflammation as evidenced by the reduced IL-6 and TNF-α mRNA expression; (5) it prevented hepatic and aortic oxidative stress by normalizing activities of antioxidant enzymes in the liver and suppressing reactive oxygen species generation and NOX2 protein expression in both liver and aorta; (6) it inhibited oxLDL-induced injury, monocytes adhesion and oxidative stress in HUVECs and (7) inhibited macrophage foam cell formation and enhanced cholesterol efflux. CONCLUSIONS: These findings suggest that dihydromyricetin could reduce atherosclerosis via its pleiotropic effects, including improvement of endothelial dysfunction, inhibition of macrophage foam cell formation, amelioration of lipid profiles, anti-inflammatory action and anti-oxidative effect.

PPAR-γ is involved in the protective effect of 2,3,4',5-tetrahydroxystilbene-2-O-beta-D-glucoside against cardiac fibrosis in pressure-overloaded rats.

2, 3, 4', 5-tetrahydroxystilbene-2-0-ß-D glucoside (TSG) could inhibit cardiac remodeling in response to pressure overload. Peroxisome proliferator-activated receptor gamma (PPAR-γ) has been recognized as a potent, endogenous antifibrotic factor and maintaining a proper expression level in myocardium is necessary for assuring that structure and function of heart adapt to pressure overload stress. The aim of the present study was to investigate whether PPAR-γ is involved in the beneficial effect of TSG on pressure overload-induced cardiac fibrosis. TSG (120mg/kg/day) or TSG (120mg/kg/day) plus the PPAR-γ antagonist GW9662 (1mg/kg/day) was administered to rats with pressure overload induced by abdominal aortic banding. 30 days later, pressure overload-induced hypertension, cardiac dysfunction and fibrosis were significantly inhibited by TSG. TSG also significantly reduced collagen I, collagen III, fibronectin and plasminogen activator inhibitor (PAI)-1 expression, as makers of myocardial fibrosis. Theses anti-fibrotic effects of TSG in pressure overloaded hearts could be abrogated by co-treatment with GW9662. Accordingly, upregulated PPAR-γ protein expression by TSG in pressure overloaded hearts was also reversed by co-treatment with GW9662. Additionally, the inhibitory effects of TSG on angiotensin II induced cardiac fibroblasts proliferation, differentiation and expression of collagen I and III, fibronectin and PAI-1 were abrogated by PPAR-γ antagonist GW9662 and PPAR-γ silencing. Furthermore, TSG directly increased PPAR-γ gene expression at gene promoter, mRNA and protein level in angiotensin II-treated cardiac fibroblats in vitro. Our results suggested that upregualtion of endogenous PPAR-γ expression by TSG may be involved in its beneficial effect on pressure overload-induced cardiac fibrosis.