EGCG Blocked Phenylephrin-Induced Hypertrophy in H9C2 Cardiomyocytes, by Activating AMPK-Dependent Pathway

Protective Role of (-)-Epicatechin on Trimethylamine-N-Oxide (TMAO)-Induced Cardiac Hypertrophy via SP1/SIRT1/SUMO1 Signaling Pathway

(-)-Epicatechin (EPI) is beneficial for cardiovascular health. Trimethylamine N-oxide (TMAO), a gut microbe-derived food metabolite, is strongly associated with the risk of cardiovascular diseases. However, the effects and underlying mechanisms of EPI on TMAO-induced cardiac hypertrophy remain unclear. This study aimed to determine whether EPI inhibits TMAO-induced cardiac hypertrophy. Plasma levels of TMAO in control participants and patients with cardiac hypertrophy were measured and analyzed. Male C57BL/6 mice were randomly divided into control group, TMAO group, EPI group and TMAO + EPI group. According to the groups assignments, mice received intraperitoneal (i.p.) injection of normal saline or i.p. injection of TMAO (150 mg/kg/day) for 14 days. The EPI group was given intragastric (i.g.) administration of EPI alone (1 mg/kg/day) for 21 days, and TMAO + EPI group received i.g. administration of EPI for 7 days before starting i.p. injection of TMAO, continuing until the end of the TMAO treatment. Histological analyses of the mice's hearts was accessed by H&E and Masson staining. In vitro, H9c2 cells were induced to hypertrophy by TMAO (10 µM) for 24 h and were pre-treated with or without EPI (10 µM) for 1 h. Protein level of cardiac hypertrophy markers and Sp1/SIRT1/SUMO1 pathway were determined by western blot. The plasma level of TMAO was 2.66 ± 1.59 μmol/L in patients with cardiac hypertrophy and 0.62 ± 0.30 μmol/L in control participants. EPI attenuated TMAO-induced hypertrophy in H9c2 cells. In vivo, TMAO induced cardiac hypertrophy and impaired the cardiac function of mice. Pathological staining showed that TMAO induced cardiac hypertrophy and collagen deposition in mice. EPI treatment improved the cardiac function, inhibited the myocardial hypertrophy induced by TMAO. EPI significantly attenuated the TMAO-induced upregulation of ANP and BNP and the downregulation of SP1, SIRT1 and SUMO1 in vivo and in vitro. EPI may suppress TMAO-induced cardiac hypertrophy by activating the Sp1/SIRT1/SUMO1 signaling pathway.

AMPK and metabolic disorders: The opposite roles of dietary bioactive components and food contaminants

AMPK is a key player in a variety of metabolic and physiological processes, which might be considered one of the most promising targets for both prevention and treatment of metabolic syndrome and its associated diseases. Many dietary components and contaminants have been recently demonstrated to prevent or promote the development these diseases via AMPK-mediated pathways. AMPK can be activated by diverse phytochemical substances such as EGCG, chicoric acid, tomatidine, and others, all of which have been found to contribute to preventing or ameliorating chronic disorders. On the other hand, recent studies have found that metabolic disruptions induced by pesticides such as 1,3-Dichloro-2-propanol, imidacloprid, permethrin, are attributed to the inactivation of AMPK. This review may contribute to the development of functional foods for treatment of metabolic syndrome and associated diseases through modulating AMPK pathway.

Effect of Postnatal Epigallocatechin-Gallate Treatment on Cardiac Function in Mice Prenatally Exposed to Alcohol

Prenatal alcohol exposure affects the cardiovascular health of the offspring. Epigallocatechin-3-gallate (EGCG) may be a protective agent against it, but no data are available regarding its impact on cardiac dysfunction. We investigated the presence of cardiac alterations in mice prenatally exposed to alcohol and the effect of postnatal EGCG treatment on cardiac function and related biochemical pathways. C57BL/6J pregnant mice received 1.5 g/kg/day (Mediterranean pattern), 4.5 g/kg/day (binge pattern) of ethanol, or maltodextrin until Day 19 of pregnancy. Post-delivery, treatment groups received EGCG-supplemented water. At post-natal Day 60, functional echocardiographies were performed. Heart biomarkers of apoptosis, oxidative stress, and cardiac damage were analyzed by Western blot. BNP and Hif1α increased and Nrf2 decreased in mice prenatally exposed to the Mediterranean alcohol pattern. Bcl-2 was downregulated in the binge PAE drinking pattern. Troponin I, glutathione peroxidase, and Bax increased in both ethanol exposure patterns. Prenatal alcohol exposure led to cardiac dysfunction in exposed mice, evidenced by a reduced ejection fraction, left ventricle posterior wall thickness at diastole, and Tei index. EGCG postnatal therapy restored the physiological levels of these biomarkers and improved cardiac dysfunction. These findings suggest that postnatal EGCG treatment attenuates the cardiac damage caused by prenatal alcohol exposure in the offspring.

Metabolic regulation of (-)-epicatechin and the colonic metabolite 2,3-dihydroxybenzoic acid on the glucose uptake, lipid accumulation and insulin signalling in cardiac H9c2 cells

Epicatechin (EC) and main colonic phenolic acids derived from flavonoid intake have been suggested to exert healthful effects, although their mechanism of action remains unknown. Heart damage is highly prevalent in metabolic diseases, and the failure of this organ is a major cause of death worldwide. In this study, the modulation of the energy metabolism and insulin signalling by the mentioned compounds in cardiac H9c2 cells was evaluated. Incubation of cells with EC (1-20 μM) and 2,3-dihydroxybenzoic acid (DHBA, 10 μM) reduced glucose uptake, and both compounds decreased lipid accumulation at concentrations higher than 0.5 μM. EC and DHBA also increased the tyrosine phosphorylated and total insulin receptor (IR) levels, and activated the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway in cardiac H9c2 cells. Interestingly, EC and DHBA did not modify glucose transporters (SGLT-1 and GLUT-1) levels, and increased GLUT-4 values. In addition, EC and DHBA decreased cluster of differentiation 36 (CD36) and fatty acid synthase (FAS) values, and enhanced carnitine palmitoyl transferase 1 (CPT1) and proliferator activated receptor α (PPARα) levels. By using specific inhibitors of AKT and 5'-AMP-activated protein kinase (AMPK), the participation of both proteins in EC- and DHBA-mediated regulation on glucose uptake and lipid accumulation was shown. Taken together, EC and DHBA modulate glucose uptake and lipid accumulation via AKT and AMPK, and reinforce the insulin signalling by activating key proteins of this pathway in H9c2 cells.

The Prevention Role of Theaflavin-3,3'-digallate in Angiotensin II Induced Pathological Cardiac Hypertrophy via CaN-NFAT Signal Pathway

Theaflavin-3,3'-digallate (TF3) is a representative theaflavin of black tea and is remarkable for the anti-coronary heart disease effect. As an adaptive response to heart failure, pathological cardiac hypertrophy (PCH) has attracted great interest. In this study, the PCH cell model was established with H9c2 cells by angiotensin II, and the prevention effect and mechanisms of TF3 were investigated. The results showed that the cell size and fetal gene mRNA level were significantly reduced as pretreated with TF3 at the concentration range of 1-10 μM, also the balance of the redox system was recovered by TF3 at the concentration of 10 μM. The intracellular Ca2+ level decreased, Calcineurin (CaN) expression was down-regulated and the p-NFATc3 expression was up-regulated. These results indicated that TF3 could inhibit the activation of the CaN-NFAT signal pathway to prevent PCH, and TF3 may be a potentially effective natural compound for PCH and heart failure.

EGCG inhibits pressure overload-induced cardiac hypertrophy via the PSMB5/Nmnat2/SIRT6-dependent signalling pathways

AIM

Epigallocatechin-3-gallate (EGCG), the major polyphenol found in green tea, exerts multiple protective effects against cardiovascular diseases, including cardiac hypertrophy. However, the molecular mechanism underlying its anti-hypertrophic effect has not been clarified. This study revealed that EGCG could inhibit pressure overload-induced cardiac hypertrophy by regulating the PSMB5/Nmnat2/SIRT6-dependent signalling pathway.

METHODS

Quantitative real-time polymerase chain reaction and western blotting were used to determine the expression of mRNA and protein respectively. A fluorometric assay kit was used to determine the activity of SIRT6, a histone deacetylase. Luciferase reporter gene assay and electrophoretic mobility shift assay were employed to measure transcriptional activity and DNA binding activity respectively.

RESULTS

EGCG could significantly increase Nmnat2 protein expression and enzyme activity in cultured neonatal rat cardiomyocytes stimulated with angiotensin II (Ang II) and heart tissues from rats subjected to abdominal aortic constriction. Nmnat2 knockdown by RNA interference attenuated the inhibitory effect of EGCG on cardiac hypertrophy. EGCG blocked NF-κB DNA binding activity induced by Ang II, which was dependent on Nmnat2 and the subsequent SIRT6 activation. Moreover the activation of PSMB5 (20S proteasome subunit β-5, chymotrypsin-like) was required for EGCG-induced Nmnat2 protein expression. Additionally, we demonstrated that EGCG might interact with PSMB5 and inhibit the activation of the proteasome.

CONCLUSIONS

These findings serve as the first evidence that the effect of EGCG against cardiac hypertrophy may be, at least partially, attributed to the modulation of the PSMB5/Nmnat2-dependent signalling pathway, suggesting the therapeutic potential of EGCG in the prevention and treatment of cardiac hypertrophy.

Epigallocatechin-3-gallate activates the AMP-activated protein kinase signaling pathway to reduce lipid accumulation in canine hepatocytes

Epigallocatechin-3-gallate (EGCG) plays a crucial role in hepatic lipid metabolism. However, the underlying regulatory mechanism of hepatic lipid metabolism by EGCG in canine is unclear. Primary canine hepatocytes were treated with EGCG (0.01, 0.1, or 1 μM) and BML-275 (an AMP-activated protein kinase [AMPK] inhibitor) to study the effects of EGCG on the gene and protein expressions associated with AMPK signaling pathway. Data showed that treatment with EGCG had greater activation of AMPK, as well as greater expression levels and transcriptional activity of peroxisome proliferator activated receptor-α (PPARα) along with upregulated messenger RNA (mRNA) abundance and protein abundance of PPARα-target genes. EGCG decreased the expression levels and transcriptional activity of sterol regulatory element-binding protein 1c (SREBP-1c) along with downregulated mRNA abundance and protein abundance of SREBP-1c target genes. Of particular interest, exogenous BML-275 could reduce or eliminate the effects of EGCG on lipid metabolism in canine hepatocytes. Furthermore, the content of triglyceride was significantly decreased in the EGCG-treated groups. These results suggest that EGCG might be a potential agent in preventing high-fat diet-induced lipid accumulation in small animals.

Epigallocatechin-3-gallate inhibits angiotensin II-induced cardiomyocyte hypertrophy via regulating Hippo signaling pathway in H9c2 rat cardiomyocytes

Angiotensin II (AII) has been well known to induce cardiomyocyte hypertrophy. Epigallocatechin-3-gallate (EGCG) is the main active component of green tea and it has been shown to exhibit strong cardioprotective potential, although the underlying molecular mechanisms remain unclear. In this study, we investigated the role and mechanism of EGCG in preventing AII-induced cardiomyocyte hypertrophy using rat H9c2 cardiomyocytes cells. Reactive oxygen species assay, cell size, and mRNA expression of cardiac hypertrophy markers ANP and BNP were assessed in response to AII treatment. In addition, expression of proteins involved in Hippo signaling pathway were determined by western blot analysis. We found that AII treatment resulted in significant upregulation of ANP and BNP expression levels and increase in H9c2 cell size, which were markedly attenuated by EGCG treatment. Furthermore, our results suggested that EGCG inhibited AII-induced cardiac hypertrophy via regulating the Hippo signaling pathway. Therefore, EGCG may be an effective agent for preventing cardiac hypertrophy.

Molecular understanding of Epigallocatechin gallate (EGCG) in cardiovascular and metabolic diseases

ETHNOPHARMACOLOGICAL RELEVANCE

The compound epigallocatechin-3-gallate (EGCG), the major polyphenolic compound present in green tea [Camellia sinensis (Theaceae], has shown numerous cardiovascular health promoting activity through modulating various pathways. However, molecular understanding of the cardiovascular protective role of EGCG has not been reported.

AIM OF THE REVIEW

This review aims to compile the preclinical and clinical studies that had been done on EGCG to investigate its protective effect on cardiovascular and metabolic diseases in order to provide a systematic guidance for future research.

MATERIALS AND METHODS

Research papers related to EGCG were obtained from the major scientific databases, for example, Science direct, PubMed, NCBI, Springer and Google scholar, from 1995 to 2017.

RESULTS

EGCG was found to exhibit a wide range of therapeutic properties including anti-atherosclerosis, anti-cardiac hypertrophy, anti-myocardial infarction, anti-diabetes, anti-inflammatory and antioxidant. These therapeutic effects are mainly associated with the inhibition of LDL cholesterol (anti-atherosclerosis), inhibition of NF-κB (anti-cardiac hypertrophy), inhibition of MPO activity (anti-myocardial infarction), reduction in plasma glucose and glycated haemoglobin level (anti-diabetes), reduction of inflammatory markers (anti-inflammatory) and the inhibition of ROS generation (antioxidant).

CONCLUSION

EGCG shows different biological activities and in this review, a compilation of how this bioactive molecule plays its role in treating cardiovascular and metabolic diseases was discussed.

Rescue of Heart Failure by Mitochondrial Recovery

Heart failure (HF) is a multifactorial disease brought about by numerous, and oftentimes complex, etiological mechanisms. Although well studied, HF continues to affect millions of people worldwide and current treatments can only prevent further progression of HF. Mitochondria undoubtedly play an important role in the progression of HF, and numerous studies have highlighted mitochondrial components that contribute to HF. This review presents an overview of the role of mitochondrial biogenesis, mitochondrial oxidative stress, and mitochondrial permeability transition pore in HF, discusses ongoing studies that attempt to address the disease through mitochondrial targeting, and provides an insight on how these studies can affect future research on HF treatment.