Does resveratrol improve insulin signaling in chronically ischemic myocardium?

Natural and synthetic antioxidants targeting cardiac oxidative stress and redox signaling in cardiometabolic diseases

Cardiometabolic diseases (CMDs) are metabolic diseases (e.g., obesity, diabetes, atherosclerosis, rare genetic metabolic diseases, etc.) associated with cardiac pathologies. Pathophysiology of most CMDs involves increased production of reactive oxygen species and impaired antioxidant defense systems, resulting in cardiac oxidative stress (OxS). To alleviate OxS, various antioxidants have been investigated in several diseases with conflicting results. Here we review the effect of CMDs on cardiac redox homeostasis, the role of OxS in cardiac pathologies, as well as experimental and clinical data on the therapeutic potential of natural antioxidants (including resveratrol, quercetin, curcumin, vitamins A, C, and E, coenzyme Q10, etc.), synthetic antioxidants (including N-acetylcysteine, SOD mimetics, mitoTEMPO, SkQ1, etc.), and promoters of antioxidant enzymes in CMDs. As no antioxidant indicated for the prevention and/or treatment of CMDs has reached the market despite the large number of preclinical and clinical studies, a sizeable translational gap is evident in this field. Thus, we also highlight potential underlying factors that may contribute to the failure of translation of antioxidant therapies in CMDs.

3D-Printed Coronary Implants Are Effective for Percutaneous Creation of Swine Models with Focal Coronary Stenosis

Reliable, closed-chest methods for creating large animal models of acute myocardial hypoperfusion are limited. We demonstrated the feasibility and efficacy of using magnetic resonance (MR)-compatible 3D-printed coronary implants for establishing swine models of myocardial hypoperfusion. We designed, manufactured, and percutaneously deployed implants in 13 swine to selectively create focal coronary stenosis. To test the efficacy of the implants to cause hypoperfusion or ischemia in the perfused territory, we evaluated regional wall motion, myocardial perfusion, and infarction using MR imaging. The overall swine survival rate was 85% (11 of 13). The implant retrieval rate was 92% (12 of 13). Fluoroscopic angiography confirmed focal stenosis. Cine and perfusion MRI showed regional wall motion abnormalities and inducible ischemia, respectively. Late gadolinium enhancement and histopathology showed no myocardial infarction. Our minimally invasive technique has promising applications for validation of new diagnostic methods in cardiac MR. Graphical abstract Our new minimally invasive, percutaneous method for creating swine models of acute focal coronary stenosis can be used for magnetic resonance imaging studies of myocardial ischemia. Comparable to existing methods in its efficacy and reliability, this rapid prototyping technique will allow researchers to more easily conduct translational cardiac imaging studies of coronary artery disease in large animal models.

Resveratrol alleviates ischemia/reperfusion injury of diabetic myocardium via inducing autophagy

The rising incidence and complications of diabetes constitutes a major public health issue. The mortality rate of diabetes-induced myocardial ischemia/reperfusion (I/R) injury is significantly elevated. Resveratrol (RSV) is a naturally occurring polyphenol considered to be a potent cardioprotective compound. The aim of the present study was to explore the function and molecular mechanism of RSV on diabetes-induced myocardial I/R injury. Left anterior descending coronary artery ligation was performed to stimulate myocardial I/R injury in streptozotocin-induced diabetic rats. Heart electrical activity was monitored through an electrocardiogram to confirm successful models. The myocardial infarct volume was detected via 2,3,5-triphenyltetrazolium chloride staining. Western blotting was employed to examine the levels of autophagy markers. It was found that the injection of RSV mitigated the ischemia- or I/R injury-induced myocardial damage on hemodynamic function and infarct size, but the autophagy inhibitor 3-methyladenine significantly blocked the function of RSV. Furthermore, the application of RSV significantly enhanced the expression of Beclin-1 and LC-3II but inhibited the serum levels of tumor necrosis factor-α and interleukin-6. These findings revealed an alleviating effect of RSV on diabetes-induced myocardial I/R injury and provided new evidence for the successful application of RSV on the diabetic myocardium.

Investigating the Metabolic Syndrome: Contributions of Swine Models

The metabolic syndrome (MetS), a cluster of dyslipidemia, hypertension, and diabetes and an important contributor to cardiovascular morbidity and mortality, occurs in nearly 35% of adults and 50% of the aging population in the United States. However, the underlying mechanisms by which MetS orchestrates and amplifies cardiovascular events remain elusive. Furthermore, traditional therapeutic strategies addressing lifestyle modifications and individual components of MetS are often unsuccessful in decreasing morbidity due to MetS. The availability of an adequate experimental platform that mimics the complexity of MetS may allow development of novel management techniques. Swine models, including domestic pigs and minipigs, have made important contributions to our understanding of many aspects of MetS. Given their similarity to human anatomy and physiology, those models may have significant predictive power for elucidating the pathophysiology of MetS in a manner applicable to humans. Moreover, experimental maneuvers and drugs can be tested in these preclinical models before application in patients with MetS. This review highlights the utility of the pig as an animal model for metabolic disorders, which may play a crucial role in novel drug development to optimize management of MetS.

Investigating the effects of resveratrol on chronically ischemic myocardium in a swine model of metabolic syndrome: a proteomics analysis

Resveratrol has been shown to improve cardiac perfusion and ventricular function after chronic ischemic injury. Using proteomic analysis, we sought to objectively investigate potential mechanisms, by which resveratrol exerts its cardioprotective effects in the setting of metabolic syndrome and chronic myocardial ischemia. Yorkshire swine were divided into two groups based on diet: high cholesterol (n=7) or a high-cholesterol diet with supplemental resveratrol (n=6). Four weeks later, all animals underwent surgical placement of an ameroid constrictor to their left circumflex artery. Diets were continued for another 7 weeks, and then the ischemic myocardium was harvested for proteomics analysis. Proteomic analysis identified 669 common proteins between the two groups. Of these proteins, 76 were statistically different, of which 41 were characterized (P<.05). Pathway analysis demonstrated that in animals supplemented with resveratrol, there was a downregulation in several proteins involved with mitochondrial dysfunction, cell death, and unfavorable cardiac remodeling. Furthermore, there was an upregulation in proteins involved in free radical elimination. We conclude that resveratrol supplementation significantly alters several critical protein markers in the chronically ischemic myocardium. Further investigation of these proteins may help elucidate the mechanisms by which resveratrol exerts its cardioprotective effects.

The pharmacology of resveratrol in animals and humans

In addition to thousands of research papers related to resveratrol (RSV), approximately 300 review articles have been published. Earlier research tended to focus on pharmacological activities of RSV related to cardiovascular systems, inflammation, and carcinogenesis/cancer development. More recently, the horizon has been broadened by exploring the potential effect of RSV on the aging process, diabetes, neurological dysfunction, etc. Herein, we primarily focus on the in vivo pharmacological effects of RSV reported over the past 5 years (2009-2014). In addition, recent clinical intervention studies performed with resveratrol are summarized. Some discrepancies exist between in vivo studies with animals and clinical studies, or between clinical studies, which are likely due to disparate doses of RSV, experimental settings, and subject variation. Nevertheless, many positive indications have been reported with mammals, so it is reasonable to advocate for the conduct of more definitive clinical studies. Since the safety profile is pristine, an added advantage is the use of RSV as a dietary supplement. This article is part of a Special Issue entitled: Resveratrol: Challenges in translating pre-clinical findings to improved patient outcomes.

Atorvastatin regulates apoptosis in chronically ischemic myocardium

BACKGROUND

We previously demonstrated that atorvastatin upregulates proangiogenic proteins and increases arteriolar density in ischemic myocardium. Despite this, there was a lack of collateral-dependent perfusion, possibly related to apoptosis. We utilized a swine model of metabolic syndrome and chronic myocardial ischemia to investigate the effects of atorvastatin on apoptosis.

MATERIALS AND METHODS

Sixteen Ossabaw miniswine were fed a high-cholesterol diet for 14 weeks then underwent surgical placement of an ameroid constrictor to their circumflex artery inducing chronic ischemia. Eight pigs additionally received supplemental atorvastatin (1.5 mg/kg daily). Myocardium was harvested six months later for western blotting and TUNEL staining.

RESULTS

Animals supplemented with atorvastatin had significant increases in markers associated with apoptosis including p-38, BAX, and caspase 3 (p < 0.05). Atorvastatin supplementation also resulted in significant increases in expression of cell survival proteins Bcl-2 and P-ERK and an overall decrease in apoptosis demonstrated by TUNEL staining (p < 0.05).

CONCLUSIONS

Atorvastatin acts on multiple pathways and its effects on angiogenesis remain unclear. Although there is increased expression in several markers of apoptosis, key anti-apoptotic proteins were also upregulated with an overall decrease in apoptosis. Further investigation of these pathways may provide insight into the role of statins on myocardial protection after ischemia.

Resveratrol regulates autophagy signaling in chronically ischemic myocardium

OBJECTIVE

Autophagy is a cellular process by which damaged components are removed. Although autophagy can result in cell death, when optimally regulated, it might be cardioprotective. Resveratrol is a naturally occurring polyphenol also believed to be cardioprotective. Using a clinically relevant swine model of metabolic syndrome, we investigated the effects of resveratrol on autophagy in the chronically ischemic myocardium.

METHODS

Yorkshire swine were fed a regular diet (n = 7), a high cholesterol diet (n = 7), or a high cholesterol diet with supplemental resveratrol (n = 6). After 4 weeks, an ameroid constrictor was surgically placed on the left circumflex artery to induce chronic myocardial ischemia. The diets were continued another 7 weeks, and then the ischemic and nonischemic myocardium were harvested for protein analysis.

RESULTS

In the ischemic myocardium, a high cholesterol diet partly attenuated the autophagy, as determined by an increase in phosphorylated mammalian target of rapamycin (p-mTOR) and a decrease in p70 S6 kinase (P70S6K), lysosome-associated membrane protein (LAMP)-2, and autophagy-related gene 12-5 conjugate (ATG 12-5; P < .05). The addition of resveratrol blunted many of these changes, because the p-mTOR, P70S6K, and LAMP-2 levels were not significantly altered from those of the pigs fed a regular diet. Other autophagy markers were increased with a high cholesterol diet, including light chain 3A-II and beclin 1 (P < .05). In the nonischemic myocardium, beclin 1 was decreased in the high cholesterol-fed pigs (P < .05); otherwise no significant changes in protein expression were noted among the 3 groups.

CONCLUSIONS

In the chronically ischemic myocardium, resveratrol partly reversed the effects of a high cholesterol diet on autophagy. This might be a mechanism by which resveratrol exerts its cardioprotective effects.