Epigallocatechin gallate protects H9c2 cardiomyoblasts against hydrogen dioxides- induced apoptosis and telomere attrition

Emerging insights into pulmonary hypertension: the potential role of mitochondrial dysfunction and redox homeostasis

Pulmonary hypertension (PH) is heterogeneous diseases that can lead to death due to progressive right heart failure. Emerging evidence suggests that, in addition to its role in ATP production, changes in mitochondrial play a central role in their pathogenesis, regulating integrated metabolic and signal transduction pathways. This review focuses on the basic principles of mitochondrial redox status in pulmonary vascular and right ventricular disorders, a series of dysfunctional processes including mitochondrial quality control (mitochondrial biogenesis, mitophagy, mitochondrial dynamics, mitochondrial unfolded protein response) and mitochondrial redox homeostasis. In addition, we will summarize how mitochondrial renewal and dynamic changes provide innovative insights for studying and evaluating PH. This will provide us with a clearer understanding of the initial signal transmission of mitochondria in PH, which would further improve our understanding of the pathogenesis of PH.

Autologous transplantation of green tea epigallocatechin-3-gallate pretreated adipose-derived stem cells increases cardiac regenerative capability through C-X-C motif chemokine receptor 4 expression in the treatment of rats with diabetic cardiomyopathy

Cardiomyopathy is one of complications related to diabetes. Stem cell transplantation shows potential in diabetic cardiomyopathy treatment. Epigallocatechin-3-gallate (EGCG) is one of the major components found in green tea. Although stem cell transplantation and green tea EGCG supplementation show therapeutic effects on cardiomyopathy, the detailed cellular mechanisms in stem cell transplantation coupled with EGCG treatment remain unclear. This study investigates whether adipose-derived stem cells (ADSC) pretreated with EGCG show better protective effect on diabetic cardiomyopathy than ADSC without EGCG pretreatment. A cell model indicated that ADSC pretreated with EGCG increased cell functions including colony formation, migration and survival markers. All of these functions are blocked by small interfering C-X-C motif chemokine receptor 4 (siCXCR4) administration. These findings suggest that ADSC pretreatment with EGCG increases cell functions through CXCR4 expression. A diabetic animal model was designed to verify the above findings, including Sham, DM (diabetes mellitus), DM+ADSC (DM rats receiving autologous transplantation of ADSC) and DM+E-ADSC (DM rats receiving EGCG pretreated ADSC). Compared to the Sham, we found that all of pathophysiological signalings were activated in the DM group, including functional changes (decrease in ejection fraction and fractional shortening), structural changes (disarray and fibrosis) and molecular changes (increases in apoptotic, fibrotic, hypertrophic markers and decreases in survival and longevity markers). E-ADSC (DM+E-ADSC) transplantation shows significant improvement in the above pathophysiological signalings greater than ADSC (DM+ADSC). Therefore, ADSC pretreated with EGCG may contribute to clinical applications for diabetic patients with cardiomyopathy.

Epigallocatechin-3-gallate maintains Th1/Th2 response balance and mitigates type-1 autoimmune diabetes induced by streptozotocin through promoting the effect of bone-marrow-derived mesenchymal stem cells

Stem-cell-based therapy is one of the most promising therapeutic strategies owing to its regenerative and immunomodulatory properties. Epigallocatechin-3-gallate (EGCG), a known antioxidant and anti-inflammatory agent, has beneficial effects on cellular protection. We aimed to elucidate the feasibility of using EGCG, along with bone marrow-derived mesenchymal stem cells (BM-MSCs), to improve pancreatic damage through their immune regulatory functions in an experimental model of type 1 diabetes mellitus (T1DM) induced by multiple injections of streptozotocin (STZ). BM-MSCs were isolated from C57BL/6 mice and characterized. The diabetic groups were treated intraperitoneally with PBS, MSCs, EGCG, and a combination of MSCs and EGCG. Real-time PCR assays showed that MSCs with EGCG modulated T-bet and GATA-3 expression and upregulated the mRNA levels of Foxp-3 more efficiently. Analyses of spleen-isolated lymphocytes revealed that combinational treatment pronouncedly increased regulatory cytokines and decreased pro-inflammatory cytokines and splenocyte proliferation. The histopathological assessment demonstrated that co-treatment significantly reduced insulitis and recovered pancreatic islet morphology. Furthermore, the combination of MSCs and EGCG is associated with downregulated blood glucose and enhanced insulin levels. Therefore, combined therapy with EGCG and MSCs holds clinical potential for treating T1DM through synergetic effects in maintaining the Th1/Th2 response balance and promoting the regeneration of damaged pancreatic tissues.

Mechanisms Underlying the Effects of the Green Tea Polyphenol EGCG in Sarcopenia Prevention and Management

Sarcopenia is prevalent among the older population and severely affects human health. Tea catechins may benefit for skeletal muscle performance and protect against secondary sarcopenia. However, the mechanisms underlying their antisarcopenic effect are still not fully understood. Despite initial successes in animal and early clinical trials regarding the safety and efficacy of (-)-epigallocatechin-3-gallate (EGCG), a major catechin of green tea, many challenges, problems, and unanswered questions remain. In this comprehensive review, we discuss the potential role and underlying mechanisms of EGCG in sarcopenia prevention and management. We thoroughly review the general biological activities and general effects of EGCG on skeletal muscle performance, EGCG's antisarcopenic mechanisms, and recent clinical evidence of the aforesaid effects and mechanisms. We also address safety issues and provide directions for future studies. The possible concerted actions of EGCG indicate the need for further studies on sarcopenia prevention and management in humans.

Adipose-Derived Stem Cells Preincubated with Green Tea EGCG Enhance Pancreatic Tissue Regeneration in Rats with Type 1 Diabetes through ROS/Sirt1 Signaling Regulation

Type 1 diabetes stem-cell-based therapy is one of the best therapeutic approaches for pancreatic damage treatment due to stem cell tissue regeneration. Epigallocatechin gallate (EGCG) is one of the active components found in green tea. Experimental results suggest that EGCG shows beneficial effects on cell protection. This study explores whether a better pancreatic regeneration therapeutic effect could be found in mesenchymal stem cells pretreated with EGCG compared to stem cells without EGCG pretreatment. A cell model confirmed that adipose-derived stem cells (ADSC) incubated with EGCG increase cell viability under high-glucose (HG) stress. This is due to survival marker p-Akt expression. In an animal model, type 1 diabetes induced the activation of several pathological signals, including islet size reduction, extracellular fibrotic collagen deposition, oxidative stress elevation, survival pathway suppression, apoptosis signaling induction, and Sirt1 antioxidant pathway downregulation. Ordinary ADSC transplantation slightly improved the above pathological signals. Further, EGCG-pretreated ADSC transplantation significantly improved the above pathological conditions. Taken together, EGCG-pretreated ADSCs show clinical potential in the treatment of patients with type 1 diabetes through the regeneration of damaged pancreatic tissues.

Application of a Reactive Oxygen Species-Responsive Drug-Eluting Coating for Surface Modification of Vascular Stents

Stent implantation is the primary method used to treat coronary heart disease. However, it is associated with complications such as restenosis and late thrombosis. Despite surface modification being an effective way to improve the biocompatibility of stents, the current research studies are not focused on changes in the vascular microenvironment at the implantation site. In the present study, an adaptive drug-loaded coating was constructed on the surface of vascular stent materials that can respond to oxidative stress at the site of vascular lesions. Two functional molecules, epigallocatechin gallate (EGCG) and cysteine hydrochloride, were employed to fabricate a coating on the surface of 316L stainless steel. In addition, the coating was used as a drug carrier to load pitavastatin calcium. EGCG has antioxidant activity, and pitavastatin calcium can inhibit smooth muscle cell proliferation. Therefore, EGCG and pitavastatin calcium provided a synergistic anti-inflammatory effect. Moreover, the coating was cross-linked using disulfide bonds, which accelerated the release of the drug in response to reactive oxygen species. A positive correlation was observed between the rate of drug release and the degree of oxidative stress. Collectively, this drug-loaded oxidative stress-responsive coating has been demonstrated to significantly inhibit inflammation, accelerate endothelialization, and reduce the risk of restenosis of vascular stents in vivo.

Pathophysiology, Clinical Characteristics of Diabetic Cardiomyopathy: Therapeutic Potential of Natural Polyphenols

Diabetic cardiomyopathy (DCM) is an outcome of disturbances in metabolic activities through oxidative stress, local inflammation, and fibrosis, as well as a prime cause of fatality worldwide. Cardiovascular disorders in diabetic individuals have become a challenge in diagnosis and formulation of treatment prototype. It is necessary to have a better understanding of cellular pathophysiology that reveal the therapeutic targets and prevent the progression of cardiovascular diseases due to hyperglycemia. Critical changes in levels of collagen and integrin have been observed in the extracellular matrix of heart, which was responsible for cardiac remodeling in diabetic patients. This review explored the understanding of the mechanisms of how the phytochemicals provide cardioprotection under diabetes along with the caveats and provide future perspectives on these agents as prototypes for the development of drugs for managing DCM. Thus, here we summarized the effect of various plant extracts and natural polyphenols tested in preclinical and cell culture models of diabetic cardiomyopathy. Further, the potential use of selected polyphenols that improved the therapeutic efficacy against diabetic cardiomyopathy is also illustrated.

MiR-181c protects cardiomyocyte injury by preventing cell apoptosis through PI3K/Akt signaling pathway

Background

Cardiomyocyte apoptosis plays an important role in the development of heart failure, which leads to high mortality in patients with cardiovascular diseases. In this study, we are focused to identify the role of miRNA-181c in the regulating of myocardial tissue apoptosis in the doxorubicin (DOX) or hypoxia/reoxygenation (H/R) induced H9C2 cardiomyocyte injury.

Methods

DOX-induced heart failure animal model was established using mice. Total RNA was extracted from tissue and cell using Trizol. RT-PCR was conducted for real-time RNA quantification. H9c2 cells were collected and labeled using an Annexin V-PI apoptosis kit. Flow cytometry was conducted to identify the cell apoptosis. Rat cardiomyocyte H9c2 cell was treated by 16 hours' hypoxia and 2 hours' reoxygenation to induce cell apoptosis. TUNEL assay was employed for myocardial tissue apoptosis analysis.

Results

It was revealed that miR-181c was suppressed on the heart tissue of DOX-induced heart failure animal model. We observed miR-181c overexpression reduced apoptosis through TUNEL assay, which suggested the inhibitory effect of miR-181c on myocardial tissue apoptosis. Transfection of miR-181c mimic could decrease cell apoptosis in H/R treated H9C2 cells in vitro. Under the stimulation of H/R or DOX, miR-181c could downregulate protein expression of Fas, IL-6 and TNF-α, and upregulated Bcl2 and the phosphorylation of Akt.

Conclusions

Our study revealed that miR-181c protected heart failure by impeding cardiomyocyte apoptosis through PI3K/Akt pathway, implying the therapeutic role of miR-181c during the exacerbation of the cardiovascular disease.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

Crocin protects cardiomyocytes against LPS-Induced inflammation

BACKGROUND

Sepsis causes organ dysfunctions via elevation of oxidative stress and inflammation. Lipopolysaccharide (LPS) is the major surface molecule of most gram-negative bacteria and routinely used as a sepsis model in investigation studies. Crocin is an active compound of saffron which has different pharmacological properties such as anti-oxidant and anti-inflammatory. In this research, the protective effect of crocin was evaluated against LPS-induced toxicity in the embryonic cardiomyocyte cell line (H9c2).

METHODS

The cells were pre-treated with different concentration of crocin (10, 20 and 40 μM) for 24 h, and then LPS was added (10 μg/ml) for another 24 h. Afterward, the percentage of cell viability and the levels of inflammatory cytokines (TNF-α, PGE2, IL-1β, and IL-6), gene expression levels (TNF-α, COX-2, IL-1β, IL-6, and iNOS), and the level of nitric oxide (NO) and thiol were measured.

RESULTS

Our results showed that LPS reduced cell viability, increased the levels of cytokines, gene-expression, nitric oxide, and thiol. Crocin attenuated the LPS-induced toxicity in H9c2 cells via reducing the levels of inflammatory factors (TNF-α, PGE2, IL-1β, and IL-6, p < 0.001), gene expression (TNF-α, COX-2, IL-1β, IL-6, and iNOS, p < 0.001), and NO (p < 0.001), whereas increased the level of thiol content (p < 0.001).

CONCLUSION

The observed results revealed that crocin has preventive effects on the LPS induced sepsis and its cardiac toxicity in-vitro model. Probably, these findings are related to anti-inflammatory and anti-oxidant properties of crocin. However, performing further animal studies are necessary to support the therapeutic effects of crocin in septic shock cardiac dysfunction.

(-)-Epigallocatechin-3-gallate suppresses cigarette smoke-induced inflammation in human cardiomyocytes via ROS-mediated MAPK and NF-κB pathways

BACKGROUND

Cigarette smoking is the leading cause for the initiation and development of cardiovascular disease (CVD). Oxidative stress and inflammatory responses play important roles in the pathophysiological processes of smoking-induced cardiac injury. (-)-epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea, which is made from Camellia sinensis leaves, has been reported to possess potent anti-oxidant property.

PURPOSE

This study aims to investigate whether the antioxidant EGCG could alleviate cigarette smoke medium (CSM)-induced inflammation in human AC16 cardiomyocytes in vitro.

METHODS

Human AC16 cardiomyocytes were pre-treated with EGCG, N-acetyl-L-cysteine (NAC), or specific inhibitors for 30 min before 4% CSM was added. Supernatant was collected for determination of interleukin (IL)-8 by ELISA and cells were collected for flow cytometry, biochemical assays and Western blot analysis.

RESULTS

EGCG treatment significantly attenuated CSM-induced oxidative stress as evidenced by reducing intracellular and mitochondrial reactive oxygen species (ROS) generations and preventing antioxidant depletion. EGCG treatment reduced CSM-induced inflammatory chemokine interleukin (IL)-8 productions in the supernatant via the inhibition of ERK1/2, p38 MAPK and NF-κB pathways. EGCG treatment further inhibited CSM-induced cell apoptosis.

CONCLUSION

Taken together, EGCG protected against CSM-induced inflammation and cell apoptosis by attenuating oxidative stress via inhibiting ERK1/2, p38 MAPK, and NF-κB activation in AC16 cardiomyocytes. These findings suggest that EGCG with its antioxidant, anti-inflammatory and anti-apoptotic properties may act as a promising cardioprotective agent against ROS-mediated cardiac injury.

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.

Recent Advances in the Understanding of the Health Benefits and Molecular Mechanisms Associated with Green Tea Polyphenols

Tea, leaf, or bud from the plant Camellia sinensis, make up some of the beverages popularly consumed in different parts of the world as green tea, oolong tea, or black tea. More particularly, as a nonfermented tea, green tea has gained more renown because of the significant health benefits assigned to its rich content in polyphenols. As a main constituent, green tea polyphenols were documented for their antioxidant, anti-inflammation, anticancer, anticardiovascular, antimicrobial, antihyperglycemic, and antiobesity properties. Recent reports demonstrate that green tea may exert a positive effect on the reduction of medical chronic conditions such as cardiovascular disease, cancer, Alzheimer's disease, Parkinson's disease, and diabetes. The health benefits of green teas, in particular EGCG, are widely investigated, and these effects are known to be primarily associated with the structure and compositions of its polyphenols. This Review focuses on the diverse constituents of green tea polyphenols and their molecular mechanisms from the perspective of their potential therapeutic function. Recent advances of green tea polyphenols on their bioavailability, bioaccessibility, and microbiota were also summarized in this article. Dietary supplementation with green tea represents an attractive alternative toward promoting human health.

Protective effect of rutin isolated from Spermococe hispida against cobalt chloride-induced hypoxic injury in H9c2 cells by inhibiting oxidative stress and inducing apoptosis

BACKGROUND

Cardiovascular disease and its related deaths are increasing in the modern world. Therefore, there is a need to identify a plant based nutraceutical supplement with potent activity.

HYPOTHESIS/PURPOSE

Reportedly, the protective effect of the rutin in hypoxia-induced cardiomyocytes is due to the activation of molecular networks related to programmed cell death.

STUDY DESIGN-METHODS

Phytochemical methods and advanced analytical methods were employed to isolate natural products from Spermococe hispida their effects in cardiomyocyets.

RESULTS

We reports herein that CoCl₂-induced hypoxic condition significantly decreased cell viability as evidenced by MTT assay and cell cycle analysis. Western blot studies revealed an up-regulation of HIF-1α, BAX and caspase and down-regulation of BCl-2 expression, followed by modulation of Akt, p-Akt, p38 and p-p38. The oxidative abnormalities were ameliorated by rutin pretreatment, as deduced by the reduced CoCl₂-induced cytotoxicity, MDA concentration and LDH activity and the enhanced levels of GSH and SOD in a dose-dependent manner. Rutin protects H9c2 cells from CoCl₂-induced hypoxic damage by mitigating oxidative stress and preserving cell viability by modulating the antiapoptotic proteins.

CONCLUSION

The overall findings reinforce the cardioprotective action of rutin, a potential source of antioxidant of natural origin, which may help in mitigating the progress of oxidative stress in hypoxic conditions such as myocardial infarction and stroke.

Carbon monoxide (CO) inhibits hydrogen peroxide (H2O2)-induced oxidative stress and the activation of NF-κB signaling in lens epithelial cells

Lens epithelial cells (LECs) play a critical role in the maintenance of clear crystalline lens. Previously, we reported that heme oxygenase-1 can protect LECs from hydrogen peroxide (H₂O₂)-induced apoptosis and oxidative stress; however, to the best of our knowledge, these protection mechanisms have not yet been explained. As carbon monoxide (CO) is an active by-product of heme degradation, we investigated its cytoprotective mechanism in both H₂O₂-treated human LECs (SRA 01/04) and primary rabbit LECs. CO-releasing molecule-3 was used as a CO releasing vehicle. The nuclear translocation of nuclear factor kappa B (NF-κB) p65 was monitored by Western blot and immunofluorescence staining. In addition, the levels of intracellular reactive oxygen species (ROS), antioxidants, and apoptotic molecules (Bax, Bcl-2, and caspase-3) were measured. Furthermore, cell apoptosis rate was quantified by flow cytometry. Our results disclosed that low concentrations of CO released from CO-releasing molecule-3 can attenuate NF-κB p65 nuclear translocation, reduce ROS generation, and enhance intracellular glutathione and superoxide dismutase levels. Moreover, low concentrations of CO inhibited H₂O₂-induced apoptotic molecules, thereby decreasing the apoptosis of LECs. These findings suggest that low concentrations of CO protect LECs from H₂O₂-induced oxidative damage by attenuating NF-κB p65 nuclear translocation, reducing the generation of ROS and apoptotic molecules, and restoring antioxidant enzyme levels, thereby inhibiting LECs apoptosis.

Cardiac telomere length in heart development, function, and disease

Telomeres are repetitive nucleoprotein structures at chromosome ends, and a decrease in the number of these repeats, known as a reduction in telomere length (TL), triggers cellular senescence and apoptosis. Heart disease, the worldwide leading cause of death, often results from the loss of cardiac cells, which could be explained by decreases in TL. Due to the cell-specific regulation of TL, this review focuses on studies that have measured telomeres in heart cells and critically assesses the relationship between cardiac TL and heart function. There are several lines of evidence that have identified rapid changes in cardiac TL during the onset and progression of heart disease as well as at critical stages of development. There are also many factors, such as the loss of telomeric proteins, oxidative stress, and hypoxia, that decrease cardiac TL and heart function. In contrast, antioxidants, calorie restriction, and exercise can prevent both cardiac telomere attrition and the progression of heart disease. TL in the heart is also indicative of proliferative potential and could facilitate the identification of cells suitable for cardiac rejuvenation. Although these findings highlight the involvement of TL in heart function, there are important questions regarding the validity of animal models, as well as several confounding factors, that need to be considered when interpreting results and planning future research. With these in mind, elucidating the telomeric mechanisms involved in heart development and the transition to disease holds promise to prevent cardiac dysfunction and potentiate regeneration after injury.

Effects of Polyphenols on Oxidative Stress-Mediated Injury in Cardiomyocytes

Cardiovascular diseases are the main cause of mortality and morbidity in the world. Hypertension, ischemia/reperfusion, diabetes and anti-cancer drugs contribute to heart failure through oxidative and nitrosative stresses which cause cardiomyocytes nuclear and mitochondrial DNA damage, denaturation of intracellular proteins, lipid peroxidation and inflammation. Oxidative or nitrosative stress-mediated injury lead to cardiomyocytes apoptosis or necrosis. The reactive oxygen (ROS) and nitrogen species (RNS) concentration is dependent on their production and on the expression and activity of anti-oxidant enzymes. Polyphenols are a large group of natural compounds ubiquitously expressed in plants, and epidemiological studies have shown associations between a diet rich in polyphenols and the prevention of various ROS-mediated human diseases. Polyphenols reduce cardiomyocytes damage, necrosis, apoptosis, infarct size and improve cardiac function by decreasing oxidative stress-induced production of ROS or RNS. These effects are achieved by the ability of polyphenols to modulate the expression and activity of anti-oxidant enzymes and several signaling pathways involved in cells survival. This report reviews current knowledge on the potential anti-oxidative effects of polyphenols to control the cardiotoxicity induced by ROS and RNS stress.

Polyphenols: Potential source of drugs for the treatment of ischaemic heart disease

Polyphenols, which are naturally present in plants, have been studied for their chemical and pharmacological properties. Polyphenols have been found to exhibit various bioactivities such as antioxidant, free radical scavenging and anti-inflammatory effects, in addition to regulating the intracellular free calcium levels. These bioactivities are related to the underlying mechanisms of ischaemic heart diseases. Pharmacological studies have proven polyphenols to be effective in treating cardiovascular diseases in various ways, particularly ischaemic heart diseases. Based on their mode of action, we propose that some polyphenols can be developed as drugs to treat ischaemic heart diseases. For this purpose, a strategy to evaluate the therapeutic value of drugs for ischaemic heart diseases is needed. Despite several advances in percutaneous coronary intervention (PCI), the incidence of myocardial infarction and deaths due to cardiovascular diseases has not decreased markedly in China. Due to their pleiotropic properties and structural diversity, polyphenols have been of great interest in pharmacology. In the present review, we summarize the pharmacological effects and mechanisms of polyphenols reported after 2000, and we analyse the benefits or druggability of these compounds for ischaemic heart diseases.

Molecular targets for anti-oxidative protection of green tea polyphenols against myocardial ischemic injury

Ischemic heart disease is the leading cause of death worldwide. An improved understanding of the mechanisms involved in myocardial injury would allow intervention downstream in the pathway where certain drugs including natural products could be efficiently applied to target the end effectors of the cell death pathway. Green tea polyphenols (GTPs) have potent anti-oxidative capabilities, which may account for their beneficial effects in preventing oxidative stress associated with ischemia injury. Although studies have provided convincing evidence to support the protective effects of GTPs in cardiovascular system, the potential end effectors that mediate cardiac protection are only beginning to be addressed. Proteomics analyses widely used to identify the protein targets for many cardiovascular diseases have advanced the discovery of the signaling mechanism for GTPs-mediated cardio-protection. This review focuses on putative triggers, mediators, and end effectors for the GTPs-mediated cardio-protection signaling pathways engaged in myocardial ischemia crisis, allowing a promising natural product to be used for ameliorating oxidative stress associated with ischemic heart diseases.

Protective effect of (-)-epigallocatechin-3-gallate against cisplatin-induced ototoxicity

Objective: Ototoxicity due to cisplatin therapy interferes with treatment and often forces a reduction in the dosage, duration and frequency of the cisplatin therapy. (-)-Epigallocatechin-3-gallate is known to have the highest antioxidant potency among all tea catechins. This study aimed to investigate the effect of (-)-epigallocatechin-3-gallate on cisplatin ototoxicity in an auditory cell line: House Ear Institute-Organ of Corti 1 cells. Methods: Cultured House Ear Institute-Organ of Corti 1 cells were exposed to cisplatin with or without pre-treatment with (-)-epigallocatechin-3-gallate. Cell viability was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Hoechst 33258 staining was used to identify cells undergoing apoptosis. Western blot analysis was conducted to determine whether (-)-epigallocatechin-3-gallate inhibited cisplatin-induced caspase activation. Intracellular reactive oxygen species production was examined to investigate whether (-)-epigallocatechin-3-gallate was capable of scavenging cisplatin-induced reactive oxygen species accumulation. Results: Cell viability significantly increased in cells pre-treated with (-)-epigallocatechin-3-gallate compared with cells exposed to cisplatin alone. Cisplatin increased cleaved caspase-3 on Western blot analysis; however, pre-treatment with (-)-epigallocatechin-3-gallate inhibited the expression of caspase-3. (-)-Epigallocatechin-3-gallate attenuated reactive oxygen species production and apoptosis in House Ear Institute-Organ of Corti 1 cells. Conclusion: (-)-Epigallocatechin-3-gallate protected against cisplatin cytotoxicity through anti-apoptotic and anti-oxidative effects. Therefore, (-)-epigallocatechin-3-gallate could play a preventive role in cisplatin-induced ototoxicity.

MicroRNA-214 protects cardiac myocytes against H2O2-induced injury

Reactive oxygen species (ROS)-induced cardiac myocyte injury resulting from changes in the expression levels of multiple genes plays a critical role in the pathogenesis of numerous heart diseases. The purpose of this study was to determine the potential roles of microRNA-214 (miR-214) in hydrogen peroxide (H2O2)-mediated gene regulation in cardiac myocytes. In this study, we used quantitative real-time RT-PCR (qRT-PCR) to demonstrate that miR-214 was upregulated in cardiac myocytes after treatment with H2O2. We transfected cells with pre-miR-214 to upregulate miR-214 expression and transfected cells with a miR-214 inhibitor (anti-miR-214) to downregulate miR-214 expression. H2O2-induced cardiac cell apoptosis was detected by flow cytometry. The level of apoptosis was increased by the miR-214 inhibitor and decreased by pre-miR-214. Therefore, we believe that miR-214 plays a positive role in H2O2-induced cardiac cell apoptosis. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is constitutively active and is considered to be the primary downregulator of the pro-oncogenic PI3K/Akt pathway. Western blot analysis revealed that the expression of the PTEN protein in cardiac myocytes decreased after H2O2 induction. Anti-miR-214 increased PTEN protein expression level, in contrast, pre-miR-214 decreased the PTEN protein expression level in cultured cardiac myocytes. These results indicate that PTEN is regulated by miR-214 and serves as an important target of miR-214 in cardiac myocytes. In conclusion, miR-214 is sensitive to H2O2 stimulation, and miR-214 protects cardiac myocytes against H2O2-induced injury via one of its targets, PTEN.

Epigallocatechin-3-gallate-mediated cardioprotection by Akt/GSK-3β/caveolin signalling in H9c2 rat cardiomyoblasts

Background

Epigallocatechin-3-gallate (EGCg) with its potent anti-oxidative capabilities is known for its beneficial effects ameliorating oxidative injury to cardiac cells. Although studies have provided convincing evidence to support the cardioprotective effects of EGCg, it remains unclear whether EGCg affect trans-membrane signalling in cardiac cells. Here, we have demonstrated the potential mechanism for cardioprotection of EGCg against H₂O₂-induced oxidative stress in H9c2 cardiomyoblasts.

Results

Exposing H9c2 cells to H₂O₂ suppressed cell viability and altered the expression of adherens and gap junction proteins with increased levels of intracellular reactive oxygen species and cytosolic Ca²⁺. These detrimental effects were attenuated by pre-treating cells with EGCg for 30 min. EGCg also attenuated H₂O₂-mediated cell cycle arrest at the G1-S phase through the glycogen synthase kinase-3β (GSK-3β)/β-catenin/cyclin D1 signalling pathway. To determine how EGCg targets H9c2 cells, enhanced green fluorescence protein (EGFP) was ectopically expressed in these cells. EGFP-emission fluorescence spectroscopy revealed that EGCg induced dose-dependent fluorescence changes in EGFP expressing cells, suggesting that EGCg signalling events might trigger proximity changes of EGFP expressed in these cells.

Proteomics studies showed that EGFP formed complexes with the 67 kD laminin receptor, caveolin-1 and -3, β-actin, myosin 9, vimentin in EGFP expressing cells. Using in vitro oxidative stress and in vivo myocardial ischemia models, we also demonstrated the involvement of caveolin in EGCg-mediated cardioprotection. In addition, EGCg-mediated caveolin-1 activation was found to be modulated by Akt/GSK-3β signalling in H₂O₂-induced H9c2 cell injury.

Conclusions

Our data suggest that caveolin serves as a membrane raft that may help mediate cardioprotective EGCg transmembrane signalling.

(-)-Epigallocatechin-gallate (EGCG) stabilize the mitochondrial enzymes and inhibits the apoptosis in cigarette smoke-induced myocardial dysfunction in rats

The present study brings out the preventive role of (-)-epigallocatechin-gallate (EGCG) on cardiac mitochondrial metabolism and apoptosis in cigarette smoke (CS)-exposed rats. The CS-exposed rats showed significantly decreased activities of TCA cycle enzymes and mitochondrial enzymatic antioxidants, on the other hand, mitochondrial lipid peroxidation was increased and GSH level was decreased. Further, CS exposure was found to induce cardiac apoptosis through release of cytochrome c into the cytosol, cleavage of pro-caspase-3 to active caspase-3, up-regulation of pro-apoptotic (Bax) and down-regulation of antiapoptotic (Bcl-2) molecules. The CS-induced apoptosis was further confirmed by mitochondrial and nuclear ultra structural apoptotic features as evaluated by electron microscopic studies. EGCG supplementation shelters the activities of TCA cycle enzymes and antioxidant enzymes, with concomitant decrease in lipid peroxidation and increase in GSH level. EGCG administration inhibited apoptosis through the inhibition of cytochrome c release into cytosol, activation of pro-caspase-3, down regulation of Bax and significant up regulation of Bcl-2. EGCG reversed the ultra structural apoptotic alterations of mitochondria and nucleus. The present study has provided experimental evidences that the EGCG treatment enduring to cardio protection at mitochondrial level.

Mitochondrial dysfunction promotes breast cancer cell migration and invasion through HIF1α accumulation via increased production of reactive oxygen species

Although mitochondrial dysfunction has been observed in various types of human cancer cells, the molecular mechanism underlying mitochondrial dysfunction mediated tumorigenesis remains largely elusive. To further explore the function of mitochondria and their involvement in the pathogenic mechanisms of cancer development, mitochondrial dysfunction clones of breast cancer cells were generated by rotenone treatment, a specific inhibitor of mitochondrial electron transport complex I. These clones were verified by mitochondrial respiratory defect measurement. Moreover, those clones exhibited increased reactive oxygen species (ROS), and showed higher migration and invasive behaviors compared with their parental cells. Furthermore, antioxidant N-acetyl cysteine, PEG-catalase, and mito-TEMPO effectively inhibited cell migration and invasion in these clones. Notably, ROS regulated malignant cellular behavior was in part mediated through upregulation of hypoxia-inducible factor-1 α and vascular endothelial growth factor. Our results suggest that mitochondrial dysfunction promotes cancer cell motility partly through HIF1α accumulation mediated via increased production of reactive oxygen species.

Silibinin protects H9c2 cardiac cells from oxidative stress and inhibits phenylephrine-induced hypertrophy: potential mechanisms

Cardiac hypertrophy is the main response of the heart to various extrinsic and intrinsic stimuli, and it is characterized by specific molecular and phenotypic changes. Recent in vitro and in vivo studies indicate the involvement of reactive oxygen species in the hypertrophic response. In this study, silibinin, a plant flavonolignan extracted from milk thistle with potent antioxidant activity, was evaluated for its effects in (a) preventing hydrogen peroxide (H2O2)-induced cellular damage and (b) blocking the phenylephrine-induced hypertrophic response. Using the in vitro model of embryonic rat heart-derived H9c2 cells, we showed that silibinin has a rather safe profile as concentrations up to 200μM did not affect cell viability. Pretreatment of H9c2 cells with silibinin resulted in better protection of H9c2 cells under conditions of H2O2-induced cellular stress compared to untreated cells as indicated by cell viability and DNA fragmentation assays. Furthermore, silibinin attenuated the phenylephrine-induced hypertrophic response as evidenced by the measurement of cell surface, up-regulation of atrial natriuretic peptide and increase of cellular protein levels. Moreover, silibinin repressed the phenylephrine-induced phosphorylation of ERK1/2 kinases, while it appeared to inhibit the weakly activated by phenylephrine phosphorylation of Akt. Based on our results, silibinin may attenuate the phenylephrine-induced hypertrophic response of H9c2 cells via antioxidant mechanisms involving mainly the inhibition of the intracellular signaling pathways mediated by ERK1/2 MAPKs and Akt.

In vitro antioxidant synergism and antagonism between food extracts can lead to similar activities in H2O2-induced cell death, caspase-3 and MMP-2 activities in H9c2 cells

BACKGROUND

The cardio-health-promoting activity of some foods may be due to their specific antioxidant content. The antioxidant activity of a mixture of plant extracts has been shown to differ from the activity of the individual extracts. As a result, the activity of the mixture can be described as synergistic, antagonistic or additive. This in vitro study evaluated the relationship between the in vitro antioxidant capacity of mixtures and their bioactivity when cardiomyocytes (H9c2) were challenged with H(2)O(2).

RESULTS

A mixture of raspberry and adzuki bean extracts produced a synergistic response and a mixture of broccoli and soybean extracts produced an antagonistic response in chemical-based antioxidant assays. When these extracts were tested in cell cultures, individually and in mixtures, the mixture of raspberry and adzuki bean protected the cardiomyocytes from H(2)O(2)-induced cell damage significantly better than the individual extracts. Conversely, the mixture of broccoli and soybean extracts was less effective in protecting H9c2 cells. The synergistic and antagonistic effects of the mixtures in protecting cell damage were brought about by enhanced or reduced ability in attenuating caspase-3 and matrix metalloproteinase-2 activities elevated by H(2)O(2).

CONCLUSION

Food mixtures with synergistic antioxidant activity and protective property against reactive oxygen species-induced cell death can potentially be incorporated into novel functional foods or beverages with optimum health benefit. The antagonistic effect of food mixtures can be a health concern and thus should be avoided.

Telomerase activity and telomere length distribution in vascular endothelial cells in a short-term culture under the presence of hydrogen peroxide

AIM

The aim of this study was to assess the biological effects of oxidative stress on human vascular endothelial cells.

METHODS

The telomeric changes and the alterations of the expression of telomere-associated proteins in human umbilical venous endothelial cells (HUVEC) cultured in the presence of hydrogen peroxide (H2 O2 ) were analyzed.

RESULTS

During the culture, the cell growth rate decreased, whereas the telomerase activity of the surviving cells increased. As the H2 O2 level increased, long telomeres decreased proportionally, thus resulting in a telomere length distribution that was rich in short telomeres. These observations suggested that H2 O2 -affected endothelial cells bear telomeric features similar to those of aged cells. In contrast, the expression of telomere-associated proteins, TRF1 and TRF2, showed different changes. TRF1 increased in relation to H2 O2 concentration, whereas TRF2 showed no significant change. The surviving cells exposed to H2 O2 showed a H2 O2 -dose dependent increase in telomerase activity, whereas the telomere protein and RNA components were only elevated in low concentrations of H2 O2 .

CONCLUSIONS

The increase in telomerase activity and TRF1 protein expression of vascular endothelial cell might show an aspect of cellular protective reaction against oxygen stress.

Plant phytochemicals as new potential drugs for immune disorders and cancer therapy: really a promising path?

Plant phytochemicals represent an exciting opportunity to maintain best health conditions through a balanced and properly administered daily nutrition or dietary supplement and have often been considered a good option for obtaining a few promising, expensive new drugs from plants. Several polyphenolic compounds, such as resveratrol, tea catechins and flavonoids, which are commonly found in vegetables, fruits and plant-derived juices or beverages, exert well-evidenced cardioprotective, neuroprotective, chemopreventive and anti-inflammatory properties, but, nevertheless, further clinical and epidemiological research is required. Most of these botanical byproducts are produced as noxious components by plants, in order to prevent pathogen colonization, insect-mediated damage and also to discourage animals from eating them. An evolutionary theory of stress adaptation would explain how these toxic substances from nature act as protective molecules. A future challenge to achieve a rather complete understanding of these chemical phenol derivatives for human health should deal with the complexity of cellular signalling networks, the epigenetic machinery endowment of the cell and the nonlinear relationship between dose and effectiveness.

Epigallocatechin-3-gallate (EGCG) protects against chromate-induced toxicity in vitro

Hexavalent chromium [Cr(VI)] is a human carcinogen that results in the generation of reactive oxygen species (ROS) and a variety of DNA lesions leading to cell death. Epigallocatechin-3-gallate (EGCG), the major polyphenol present in green tea, possesses potent antioxidative activity capable of protecting normal cells from various stimuli-induced oxidative stress and cell death. Here we demonstrated that co-treatment with EGCG protected human normal bronchial epithelial BEAS-2B cells from Cr(VI)-induced cell death in a dose-dependent manner. Cr(VI) induces apoptosis as the primary mode of cell death. Co-treatment of BEAS-2B cells with EGCG dose-dependently suppressed Cr(VI)-induced apoptosis. Fluorescence microscopic analyses and quantitative measurement revealed that EGCG significantly decreased intracellular levels of ROS induced by Cr(VI) exposure. Using a well-established K(+)/SDS precipitation assay, we further showed that EGCG was able to dose-dependently reduce DNA-protein cross-links (DPC), lesions that could be partially attributed to Cr(VI)-induced oxidative stress. Finally, analyses of Affymetrix microarray containing 28,869 well-annotated genes revealed that, among the 3412 genes changed more than 1.5-fold by Cr(VI) treatment, changes of 2404 genes (70%) were inhibited by pretreatment of EGCG. Real-time PCR confirmed the induction of 3 genes involved in cell death and apoptosis by Cr(VI), which was eliminated by EGCG. In contrast, Cr(VI) reduced the expression of 3 genes related to cellular defense, and this reduction was inhibited by EGCG. Our results indicate that EGCG protects BEAS-2B cells from Cr(VI)-induced cytotoxicity presumably by scavenging ROS and modulating a subset of genes. EGCG, therefore, might serve as a potential chemopreventive agent against Cr(VI) carcinogenesis.

The cardioprotective efficacy of TVP1022 in a rat model of ischaemia/reperfusion

BACKGROUND AND PURPOSE

Because myocardial infarction is a major cause of morbidity and mortality worldwide, protecting the heart from the ischaemia and reperfusion (I/R) damage is the focus of intense research. Based on our in vitro findings showing that TVP1022 (the S-enantiomer of rasagiline, an anti-Parkinsonian drug) possesses cardioprotective effects, in the present study we investigated the hypothesis that TVP1022 can attenuate myocardial damage in an I/R model in rats.

EXPERIMENTAL APPROACH

The model consisted of 30-min occlusion of the left anterior descending artery followed by 4 or 24 h reperfusion. In addition, we investigated the possible mechanisms of cardioprotection in H9c2 cells and neonatal rat ventricular myocytes (NRVM) exposed to oxidative stress induced by H(2) O(2) .

KEY RESULTS

TVP1022 (20 and 40 mg·kg(-1) ) administered 5 min before reperfusion followed by an additional dose 4 h after reperfusion reduced the infarct size and attenuated the decline in ventricular function. TVP1022 also attenuated I/R-induced deterioration in cardiac mitochondrial integrity evaluated by mitochondrial swelling capacity. In vitro, using H9c2 cells and NRVM, TVP1022 attenuated both serum free- and H(2) O(2) -induced damage, preserved mitochondrial membrane potential and Bcl-2 levels, inhibited mitochondrial cytochrome c release and the increase in cleaved caspase 9 and 3 levels, and enhanced the phosphorylation of protein kinase C and glycogen synthase kinase-3β.

CONCLUSIONS AND IMPLICATIONS

TVP1022 provided cardioprotection in a model of myocardial infarction, and therefore should be considered as a novel adjunctive therapy for attenuating myocardial damage resulting from I/R injuries.

Quercetin protects oligodendrocyte precursor cells from oxygen/glucose deprivation injury in vitro via the activation of the PI3K/Akt signaling pathway

The aim of this study was to investigate the protection of quercetin (QUE) on oligodendrocyte precursor cells (OPCs) from oxygen/glucose deprivation (OGD)-induced injury in vitro and explore whether the PI3K/Akt signaling pathway contributed to the protection provided by quercetin. The OGD condition was induced by including 2mM sodium dithionite (Na(2)S(2)O(4)) in glucose-free DMEM medium. The concentration of QUE in this study ranged from 3μM to 81μM. OPCs were identified by immunocytochemical staining. Cell viability was analyzed using the water soluble tetrazolium salt-8 (WST-8) and lactate dehydrogenase assay (LDH). The morphological changes of the nucleus were measured using Hoechst 33258 nuclear staining, and the ratio of apoptotic cells was determined by FITC annexin V- and propidium iodide (PI) flow cytometry assay kit. In addition, the levels of pro-apoptotic proteins such as cleaved-caspase-3 and Bax and the anti-apoptotic proteins p-Akt and Bcl-2 were quantified using western blotting. The results showed that the OPC cell survival rate was significantly increased by incubation in conditioned medium supplemented with QUE as measured by the WST-8 assay, while the LDH release rate was significantly decreased as analyzed by the LDH assay. Furthermore, apoptosis assay showed that the apoptosis ratio of OPCs was also dramatically reduced by QUE. Western blotting showed that the expression levels of Bax and cleaved-caspase-3 proteins were down-regulated, while Bcl-2 and p-Akt were up-regulated. Further study showed that the increase in p-Akt by QUE was reduced by the PI3K inhibitor LY294002. These results indicated that QUE effectively protected OPCs from OGD-induced injury and that the mechanism might be related to the activation of the PI3K/Akt signaling pathway.

Green tea catechins improve human forearm vascular function and have potent anti-inflammatory and anti-apoptotic effects in smokers

OBJECTIVE

Several epidemiological investigations have reported that green tea reduces cardiovascular and cerebral vascular risks. Green tea catechins may improve peripheral endothelial dysfunction in smokers. The purpose of this study was to elucidate the beneficial effect of green tea catechins on the repair of endothelial dysfunction in smokers.

METHODS

Thirty healthy male smokers divided into three groups ingested a green tea beverage containing 0 mg (control group), 80 mg (middle dose group) or 580 mg (high dose group) of green tea catechins (GTC) daily for two weeks, and endothelial-dependent vasodilatation was investigated by measuring forearm blood flow (FBF) response to reactive hyperemia (RH) by venous occlusion strain-gauge plethysmography.

RESULTS

An acute effect was that the FBF response to RH significantly increased 2 hr after GTC intake in the high dose group. However, no increase was observed in the other groups. The chronic administration of GTC for one or two weeks ameliorated the FBF responses to RH in the high dose group. On the other hand, no significant increase was observed in the FBF responses to RH in the other groups. Moreover, the plasma concentration of 8-OHdG, IL-6, TNF-alpha, and soluble Fas decreased significantly for two weeks in the high dose group, however, the level of IL-1 beta remained unchanged over this period.

CONCLUSION

Green tea consumption over short and long periods appears to ameliorate endothelial dysfunction by scavenging free radicals with anti-inflammatory and anti-apoptotic properties in healthy male smokers.