Molecular mechanism of (-)-epigallocatechin-3-gallate on balloon injury-induced neointimal formation and leptin expression

Exosomal MALAT1 from macrophages treated with high levels of glucose upregulates LC3B expression via miR-204-5p downregulation

BACKGROUND

Metastasis-associated lung adenocarcinoma transcript 1 ( MALAT1 ) plays a critical role in the pathophysiology of diabetes-related complications. However, whether macrophage-derived MALAT1 affects autophagic activity under hyperglycemic conditions is unclear. Therefore, we investigated the molecular regulatory mechanisms of macrophage-derived MALAT1 and autophagy under hyperglycemic conditions.

METHODS

Hyperglycemia was induced by culturing macrophages in 25 mM glucose for 1 hour. Exosomes were extracted from the culture media. A rat model of carotid artery balloon injury was established to assess the effect of MALAT1 on vascular injury. Reverse transcription, real-time quantitative polymerase chain reaction, western blotting, immunohistochemical staining, and luciferase activity assays were performed.

RESULTS

Stimulation with high levels of glucose significantly enhanced MALAT1 expression in macrophage-derived exosomes. MALAT1 inhibited miR-204-5p expression in macrophage-derived exosomes under hyperglycemic conditions. siRNA-induced silencing of MALAT1 significantly reversed macrophage-derived exosome-induced miR-204-5p expression. Hyperglycemic treatment caused a significant, exosome-induced increase in the expression of the autophagy marker LC3B in macrophages. Silencing MALAT1 and overexpression of miR-204-5p significantly decreased LC3B expression induced by macrophage-derived exosomes. Overexpression of miR-204-5p significantly reduced LC3B luciferase activity induced by macrophage-derived exosomes. Balloon injury to the carotid artery in rats significantly enhanced MALAT1 and LC3B expression, and significantly reduced miR-204-5p expression in carotid artery tissue. Silencing MALAT1 significantly reversed miR-204-5p expression in carotid artery tissue after balloon injury. MALAT1 silencing or miR-204-5p overexpression significantly reduced LC3B expression after balloon injury.

CONCLUSION

This study demonstrated that hyperglycemia upregulates MALAT1 . MALAT1 suppresses miR-204-5p expression and counteracts the inhibitory effect of miR-204-5p on LC3B expression in macrophages to promote vascular disease.

Exosomal MALAT1 Derived from High Glucose-Treated Macrophages Up-Regulates Resistin Expression via miR-150-5p Downregulation

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) plays a crucial role in the pathophysiological process associated with diabetes-related complications. The effect of high glucose levels on macrophage-derived exosomal MALAT1 is unknown. Therefore, we investigated the molecular regulatory mechanisms controlling exosomal MALAT1 in macrophages under high glucose treatment and the therapeutic target of macrophage-derived exosomal MALAT1 using a balloon injury model of vascular disease in diabetic rats. High glucose (25 mM) significantly increased MALAT1 expression in macrophage-derived exosomes. MALAT1 suppressed miR-150-5p expression in macrophage-derived exosomes under high-glucose conditions. Silencing MALAT1 using MALAT1 siRNA significantly reversed miR-150-5p expression induced by macrophage-derived exosomes. Macrophage-derived exosomes under high-glucose treatment significantly increased resistin expression in macrophages. Silencing MALAT1 and overexpression of miR-150-5p significantly decreased resistin expression induced by macrophage-derived exosomes. Overexpression of miR-150-5p significantly decreased resistin luciferase activity induced by macrophage-derived exosomes. Macrophage-derived exosome significantly decreased glucose uptake in macrophages and silencing MALAT1, resistin or overexpression of miR-150-5p significantly reversed glucose uptake. Balloon injury to the carotid artery significantly increased MALAT1 and resistin expression and significantly decreased miR-150-5p expression in arterial tissue. Silencing MALAT1 significantly reversed miR-150-5p expression in arterial tissue after balloon injury. Silencing MALAT1 or overexpression of miR-150-5p significantly reduced resistin expression after balloon injury. In conclusion, high glucose up-regulates MALAT1 to suppress miR-150-5p expression and counteracts the inhibitory effect of miR-150-5p on resistin expression in macrophages to promote vascular disease. Macrophage-derived exosomes containing MALAT1 may serve as a novel cell-free approach for the treatment of vascular disease in diabetes mellitus.

Phytotherapy for Cardiovascular Disease: A Bench-to-Bedside Approach

At present, cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, and global trends suggest that this panorama will persist or worsen in the near future. Thus, optimization of treatment strategies and the introduction of novel therapeutic alternatives for CVD represent key objectives in contemporary biomedical research. In recent years, phytotherapy-defined as the therapeutic use of whole or minimally modified plant components-has ignited large scientific interest, with a resurgence of abundant investigation on a wide array of medicinal herbs (MH) for CVD and other conditions. Numerous MH have been observed to intervene in the pathophysiology of CVD via a myriad of molecular mechanisms, including antiinflammatory, anti-oxidant, and other beneficial properties, which translate into the amelioration of three essential aspects of the pathogenesis of CVD: Dyslipidemia, atherosclerosis, and hypertension. Although the preclinical data in this scenario is very rich, the true clinical impact of MH and their purported mechanisms of action is less clear, as large-scale robust research in this regard is in relatively early stages and faces important methodological challenges. This review offers a comprehensive look at the most prominent preclinical and clinical evidence currently available concerning the use of MH in the treatment of CVD from a bench-to-bedside approach.

(-)-Epigallocatechin Gallate Promotes MicroRNA 145 Expression against Myocardial Hypoxic Injury through Dab2/Wnt3a/β-catenin

MicroRNA 145 (miR-145) is a critical modulator of cardiovascular diseases. The downregulation of myocardial miR-145 is followed by an increase in disabled-2 (Dab2) expression in cardiomyocytes. (-)-epigallocatechin gallate (EGCG) is a flavonoid that has been evaluated extensively due to its diverse pharmacological properties including anti-inflammatory effects. The aim of this study was to investigate the cardioprotective effects of EGCG under hypoxia-induced stress in vitro and in vivo. The hypoxic insult led to the suppression of miR-145 expression in cultured rat cardiomyocytes in a concentration-dependent manner. Western blotting and real-time PCR were performed. In rat myocardial infarction study, in situ hybridization, and immunofluorescent analyses were adopted. The western blot and real-time PCR data revealed that hypoxic stress with 2.5% O2 suppressed the expression of miR-145 and Wnt3a/[Formula: see text]-catenin in cultured rat cardiomyocytes but augmented Dab2. Treatment with EGCG attenuated Dab2 expression, but increased Wnt3a and [Formula: see text]-catenin in hypoxic cultured cardiomyocytes. Following in vivo myocardial infarction (MI) study, the data revealed the myocardial infarct area reduced by 48.5%, 44.6%, and 48.5% in EGCG (50[Formula: see text]mg/kg) or miR-145 dominant or Dab2 siRNA groups after myocardial infarction for 28 days, respectively. This study demonstrated that EGCG increased miR-145, Wnt3a, and [Formula: see text]-catenin expression but attenuated Dab2 expression. Moreover, EGCG ameliorated myocardial ischemia in vivo. The novel suppressive effect was mediated through the miR-145 and Dab2/Wnt3a/[Formula: see text]-catenin pathways.

Polyphenols and Oxidative Stress in Atherosclerosis-Related Ischemic Heart Disease and Stroke

Good nutrition could maintain health and life. Polyphenols are common nutrient mainly derived from fruits, vegetables, tea, coffee, cocoa, mushrooms, beverages, and traditional medicinal herbs. They are potential substances against oxidative-related diseases, for example, cardiovascular disease, specifically, atherosclerosis-related ischemic heart disease and stroke, which are health and economic problems recognized worldwide. In this study, we reviewed the risk factors for atherosclerosis, including hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette smoking as well as the antioxidative activity of polyphenols, which could prevent the pathology of atherosclerosis, including endothelial dysfunction, low-density lipoprotein oxidation, vascular smooth muscle cell proliferation, inflammatory process by monocytes, macrophages or T lymphocytes, and platelet aggregation. The strong radical-scavenging properties of polyphenols would exhibit antioxidative and anti-inflammation effects. Polyphenols reduce ROS production by inhibiting oxidases, reducing the production of superoxide, inhibiting OxLDL formation, suppressing VSMC proliferation and migration, reducing platelet aggregation, and improving mitochondrial oxidative stress. Polyphenol consumption also inhibits the development of hypertension, diabetes mellitus, hyperlipidemia, and obesity. Despite the numerous in vivo and in vitro studies, more advanced clinical trials are necessary to confirm the efficacy of polyphenols in the treatment of atherosclerosis-related vascular diseases.

Potential benefit of (-)-epigallocatechin-3-gallate for macrovascular complications in diabetes

Vascular problems are the most common complications in diabetes. Substantial evidence from epidemiological and pathophysiological studies show that hyperglycemia is a major risk factor for macrovascular complications in patients with diabetes. (-)-Epigallocatechin-3-gallate (EGCG), the major catechin derived from green tea, is known to exert a variety of cardiovascular beneficial effects. The protective effects of EGCG in diabetes are also evident. However, whether EGCG is beneficial against macrovascular complications that occur in diabetes remains unknown. Our previous studies demonstrated that treatment of EGCG inhibits high glucose-induced vascular smooth muscle cell proliferation and suppresses high glucose-mediated vascular inflammation in human umbilical vein endothelial cells. Therefore, we hypothesize that EGCG might be an effective potential candidate to reduce the macrovascular complications in diabetes.

Anti-atherosclerotic plants which modulate the phenotype of vascular smooth muscle cells

BACKGROUND

Cardiovascular disease (CVD) remains the leading cause of global death, with atherosclerosis being a major contributor to this mortality. Several mechanisms are implicated in the pathogenesis of this disease. A key element in the development and progression of atherosclerotic lesions is the phenotype of vascular smooth muscle cells. Under pathophysiologic conditions such as injury, these cells switch from a contractile to a synthetic phenotype that often possesses high proliferative and migratory capacities.

PURPOSE

Despite major advances made in the management and treatment of atherosclerosis, mortality associated with this disease remains high. This mandates that other approaches be sought. Herbal medicine, especially for the treatment of CVD, has been gaining more attention in recent years. This is in no small part due to the evidence-based values associated with the consumption of many plants as well as the relatively cheaper prices, easier access and conventional folk medicine "inherited" over generations. Sections: In this review, we provide a brief introduction about the pathogenesis of atherosclerosis then we highlight the role of vascular smooth muscle cells in this disease, especially when a phenotypic switch of these cells arises. We then thoroughly discuss the various plants that show potentially beneficial effects as anti-atherosclerotic, with prime attention given to herbs and plants that inhibit the phenotypic switch of vascular smooth muscle cells.

CONCLUSION

Accumulating evidence provides the justification for the use of botanicals in the treatment or prevention of atherosclerosis. However, further studies, especially clinical ones, are warranted to better define several pharmacological parameters of these herbs, such as toxicity, tolerability, and efficacy.

Suppressive effect of epigallocatechin-3-O-gallate on endoglin molecular regulation in myocardial fibrosis in vitro and in vivo

Epigallocatechin-3-O-gallate (EGCG), derived from green tea, has been studied extensively because of its diverse physiological and pharmacological properties. This study evaluates the protective effect of EGCG on angiotensin II (Ang II)-induced endoglin expression in vitro and in vivo. Cardiac fibroblasts (CFs) from the thoracic aorta of adult Wistar rats were cultured and induced with Ang II. Western blotting, Northern blotting, real-time PCR and promoter activity assay were performed. Ang II increased endoglin expression significantly as compared with control cells. The specific extracellular signal-regulated kinase inhibitor SP600125 (JNK inhibitor), EGCG (100 μM) and c-Jun N-terminal kinase (JNK) siRNA attenuated endoglin proteins following Ang II induction. In addition, pre-treated Ang II-induced endoglin with EGCG diminished the binding activity of AP-1 by electrophoretic mobility shift assay. Moreover, the luciferase assay results revealed that EGCG suppressed the endoglin promoter activity in Ang II-induced CFs by AP-1 binding. Finally, EGCG and the JNK inhibitor (SP600125) were found to have attenuated endoglin expression significantly in Ang II-induced CFs, as determined through confocal microscopy. Following in vivo acute myocardial infarction (AMI)-related myocardial fibrosis study, as well as immunohistochemical and confocal analyses, after treatment with endoglin siRNA and EGCG (50 mg/kg), the area of myocardial fibrosis reduced by 53.4% and 64.5% and attenuated the left ventricular end-diastolic and systolic dimensions, and friction shortening in hemodynamic monitor. In conclusion, epigallocatechin-3-O-gallate (EGCG) attenuated the endoglin expression and myocardial fibrosis by anti-inflammatory effect in vitro and in vivo, the novel suppressive effect was mediated through JNK/AP-1 pathway.

Dietary flavonoids added to pharmacological antihypertensive therapy are effective in improving blood pressure

Epidemiological studies have suggested that the daily intake of flavonoids is associated with a decreased risk of developing cardiovascular disease. Our purpose was to evaluate the effect of the addition of dietary flavonoids (DF) to antihypertensive treatment (AHT), based on telmisartan (Tms) or captopril (Cpr), on blood pressure (BP), body mass index (BMI), waist/hip ratio, leptin, lipid profile and inflammation in hypertensive young patients. An open-label, randomized, controlled trial was performed among 79 patients aged 20-55 years with grade I or grade II systemic arterial hypertension. The subjects were assigned to one of four groups for AHT plus DF during 6 months: Cpr (n = 14), Cpr + DF (n = 19), Tms (n = 25) and Tms + DF (n = 21). DF consisted of dark chocolate, dehydrated red apple and green tea in an infusion to obtain a daily dose of 425.8 ± 13.9 mg epicatechin equivalents. The BP and anthropometric parameters were measured every 2 weeks. Lipid profile, leptin and hsCRP were determined by standard methods. The combination AHT-DF produced an additional and significant reduction in (i) SBP/DBP of -5/-4 mmHg, being -7/-5 for Cpr + DF and -4/-3 for Tms + DF; (ii) triglyceride levels (-30.6%) versus AHT alone (-9.6%); and (iii) leptin: Cpr + DF versus Tms + DF (p < 0.005). Finally, C-reactive protein plasma levels were reduced significantly in all groups independently of the applied treatment. We conclude that the addition of flavonoids to pharmacological antihypertensive therapy shows additional benefits on BP, lipid profile, leptin, obesity and inflammation.