PPAR-γ and AMPK – Advantageous targets for myocardial ischemia/reperfusion therapy

Exploring the role and mechanism of hyperoside against cardiomyocyte injury in mice with myocardial infarction based on JAK2/STAT3 signaling pathway

BACKGROUND

Myocardial infarction (MI) is one of the most deadly diseases in the world. Hyperoside (Hyp) has been shown to have a protective effect on cardiovascular function through various signaling pathways, but whether it can protect myocardial infarction by regulating JAK2/STAT3 signaling pathway is unknown.

AIM OF THE STUDY

To investigate whether Hyp could protect the heart against myocardial infarction injury in mice by modulating JAK2/STAT3 signaling pathway and its potential mechanism.

METHODS

In vivo experiments, the myocardial infarction model was established by ligating the left anterior descending coronary artery (LAD) of male C57BL/6 mice permanently. The mice were divided into seven groups: sham group, MI group, MI+Hyp (9 mg/kg), MI+Hyp (18 mg/kg) group, MI+Hyp (36 mg/kg) group, MI+Captopril group (15 mg/kg) group and MI+Hyp (36 mg/kg)+AG490 (7.5 mg/kg) group. Each group of animals were given different concentrations of hyperoside, positive control drug or inhibitor of JAK2/STAT3 singaling. After 14 days of administration, the electrocardiogram (ECG), echocardiography and serum myocardial injury markers were examined; Slices of mouse myocardial tissue were assessed for histopathological changes by HE, Masson and Sirius Red staining. TTC and TUNEL staining were used to evaluate the myocardial infarction area and cardiomyocytes apoptosis respectively. The expression of JAK2/STAT3 signaling pathway, apoptosis and autophagy-related proteins were detected by western blot. In vitro experiments, rat H9c2 cardiomyocytes were deprived of oxygen and glucose (OGD) to stimulate myocardial ischemia. The experiment was divided into seven groups: Control group, OGD group, OGD+Hyp (20 μM) group, OGD+Hyp (40 μM) group, OGD+Hyp (80 μM), OGD+Captopril (10 μM) group and OGD+Hyp (80 μM)+AG490 (100 μM) group. Myocardial cell damage and redox index were measured 12 h after OGD treatment. ROS content in cardiomyocytes was detected by immunofluorescence. Cardiomyocytes apoptosis was detected by flow cytometry. The expressions of JAK2/STAT3 signaling pathway-related proteins, apoptosis and autophagy related proteins were detected by western blot.

RESULTS

In vivo, hyperoside could ameolirate ECG abnormality, increase cardiac function, reduce myocardial infarction size and significantly reduce myocardial fibrosis level and oxidation level. The experimental results in vitro showed that Hyp could reduce the ROS content in cardiomyocytes, decrease the level of oxidative stress and counteract the apoptosis induced by OGD injury . Both in vivo and in vitro experiments showed that hyperoside could increase phosphorylated JAK2 and STAT3, indicating that hyperoside could play a cardioprotective role by activating JAK2/STAT3 signaling pathway. It was also shown that hyperoside could increase the autophagy level of cardiomyocytes in vivo and in vitro. However the cardiomyocyte-protective effect of Hyp was abolished in combination with JAK2/ STAT3 signaling pathway inhibitor AG490. These results indicated that the protective effect of Hyp on cardiomyocyte injury was at least partially achieved through the activation of the JAK2/STAT3 signaling pathway.

CONCLUSION

Hyp can significantly improve cardiac function, ameliorate myocardial hypertrophy and myocardial remodeling in MI mice. The mechanism may be related to improving mitochondrial autophagy of cardiomyocytes to maintain the advantage of autophagy, and blocking apoptosis pathway through phagocytosis, thus suppressing apoptosis level of cardiomyocytes. These effects of Hyp are achieved, at least in part, by activating the JAK2/STAT3 signaling pathway.

Sulfide-modified nanoscale zero-valent iron as a novel therapeutic remedy for septic myocardial injury

INTRODUCTION

Myocardial injury is a serious complication in sepsis with high mortality. Zero-valent iron nanoparticles (nanoFe) displayed novel roles in cecal ligation and puncture (CLP)-induced septic mouse model. Nonetheless, its high reactivity makes it difficult for long-term storage.

OBJECTIVES

To overcome the obstacle and improve therapeutic efficiency, a surface passivation of nanoFe was designed using sodium sulfide.

METHODS

We prepared iron sulfide nanoclusters and constructed CLP mouse models. Then the effect of sulfide-modified nanoscale zero-valent iron (S-nanoFe) on the survival rate, blood routine parameters, blood biochemical parameters, cardiac function, and pathological indicators of myocardium was observed. RNA-seq was used to further explore the comprehensive protective mechanisms of S-nanoFe. Finally, the stability of S-nanoFe-1d and S-nanoFe-30 d, together with the therapeutic efficacy of sepsis between S-nanoFe and nanoFe was compared.

RESULTS

The results revealed that S-nanoFe significantly inhibited the growth of bacteria and exerted a protective role against septic myocardial injury. S-nanoFe treatment activated AMPK signaling and ameliorated several CLP-induced pathological processes including myocardial inflammation, oxidative stress, mitochondrial dysfunction. RNA-seq analysis further clarified the comprehensive myocardial protective mechanisms of S-nanoFe against septic injury. Importantly, S-nanoFe had a good stability and a comparable protective efficacy to nanoFe.

CONCLUSIONS

The surface vulcanization strategy for nanoFe has a significant protective role against sepsis and septic myocardial injury. This study provides an alternative strategy for overcoming sepsis and septic myocardial injury and opens up possibilities for the development of nanoparticle in infectious diseases.

Nuciferine improves cardiac function in mice subjected to myocardial ischemia/reperfusion injury by upregulating PPAR-γ

Ischemic heart disease and myocardial infarction contribute to the leading cause of death in worldwide. The prevention and management of myocardial ischemia/reperfusion (I/R) injury is an essential part of coronary heart disease surgery and is becoming a major clinical problem in the treatment of ischemic heart disease. Nuciferine has potent anti-inflammatory and antioxidative stress effects, but its role in myocardial ischemia-reperfusion (I/R) is unclear. In this study, we found that nuciferine could reduce the myocardial infarct size in a mouse myocardial ischemia-reperfusion model and improve cardiac function. Furthermore, nuciferine could effectively inhibit hypoxia and reoxygenation (H/R) stimulated apoptosis of primary mouse cardiomyocytes. In addition, nuciferine significantly reduced the level of oxidative stress. The peroxisome proliferator-activated receptor gamma (PPAR-γ) inhibitor GW9662 could reverse the protective effect of nuciferine on cardiomyocytes. These results indicate that nuciferine can inhibit the apoptosis of cardiomyocytes by upregulating PPAR-γ and reducing the I/R-induced myocardial injury in mice.

Metformin confers longitudinal cardiac protection by preserving mitochondrial homeostasis following myocardial ischemia/reperfusion injury

PURPOSE

Myocardial ischemia-reperfusion (I/R) injury is associated with systemic oxidative stress, cardiac mitochondrial homeostasis, and cardiomyocyte apoptosis. Metformin has been recognized to attenuate cardiomyocyte apoptosis. However, the longitudinal effects and pathomechanism of metformin on the regulation of myocardial mitohormesis following I/R treatment remain unclear. This study aimed to investigate the longitudinal effects and mechanism of metformin in regulating cardiac mitochondrial homeostasis by serial imaging with the 18-kDa translocator protein (TSPO)-targeted positron emission tomography (PET) tracer ¹⁸F-FDPA.

METHODS

Myocardial I/R injury was established in Sprague-Dawley rats, which were treated with or without metformin (150 mg/kg per day). Serial gated ¹⁸F-FDG and ¹⁸F-FDPA PET imaging were performed at 1, 4, and 8 weeks after surgery, followed by analysis of ventricular remodelling and cardiac mitochondrial homeostasis. The correlation between Hsp60 and ¹⁸F-FDPA uptake was analyzed. After PET imaging, the activity of antioxidant enzymes, immunostaining, and western blot analysis were performed to analyze the spatio-temporal effects and pathomechanism of metformin for cardiac protection after myocardial I/R injury.

RESULTS

Oxidative stress and apoptosis increased 1 week after myocardial I/R injury (before significant progression of ventricular remodelling). TSPO expression was correlated with Hsp60 expression and was co-localized with inflammatory CD68⁺ macrophages in the infarct area, and TSPO uptake was associated with an upregulation of AMPK-p/AMPK and a downregulation of Bcl-2/Bax. However, these effects were reversed with metformin treatment. Eight weeks after myocardial I/R injury (representing the advanced stage of heart failure), ¹⁸F-FDPA uptake in myocardial cells in the distal non-infarct area increased without CD68⁺ expression, whereas the activity decreased with metformin treatment.

CONCLUSION

Taken together, these results show that a prolonged metformin treatment has pleiotropic protective effects against myocardial I/R injury associated with a regional and temporal dynamic balance between mitochondrial homeostasis and cardiac outcome, which were assessed by TSPO-targeted imaging during cardiac remodelling.

Second malignant neoplasms in lymphomas, secondary lymphomas and lymphomas in metabolic disorders/diseases

With inconsistent findings, evidence has been obtained in recent years that metabolic disorders are closely associated with the development of lymphomas. Studies and multiple analyses have been published also indicating that some solid tumor survivors develop a secondary lymphoma, whereas some lymphoma survivors subsequently develop a second malignant neoplasm (SMN), particularly solid tumors. An interaction between the multiple etiologic factors such as genetic factors and late effects of cancer therapy may play an important role contributing to the carcinogenesis in patients with metabolic diseases or with a primary cancer. In this review, we summarize the current knowledge of the multiple etiologic factors for lymphomagenesis, focusing on the SMN in lymphoma, secondary lymphomas in primary cancers, and the lymphomas associated to metabolic disorders/diseases, which have been received less attention previously. Further, we also review the data of coexistence of lymphomas and hepatocellular carcinoma (HCC) in patients with infection of hepatitis C virus and hepatitis B virus.

Role of AMPK in Myocardial Ischemia-Reperfusion Injury-Induced Cell Death in the Presence and Absence of Diabetes

Recent studies indicate cell death is the hallmark of cardiac pathology in myocardial infarction and diabetes. The AMP-activated protein kinase (AMPK) signalling pathway is considered a putative salvaging phenomenon, plays a decisive role in almost all cellular, metabolic, and survival functions, and therefore entails precise regulation of its activity. AMPK regulates various programmed cell death depending on the stimuli and context, including autophagy, apoptosis, necroptosis, and ferroptosis. There is substantial evidence suggesting that AMPK is down-regulated in cardiac tissues of animals and humans with type 2 diabetes or metabolic syndrome compared to non-diabetic control and that stimulation of AMPK (physiological or pharmacological) can ameliorate diabetes-associated cardiovascular complications, such as myocardial ischemia-reperfusion injury. Furthermore, AMPK is an exciting therapeutic target for developing novel drug candidates to treat cell death in diabetes-associated myocardial ischemia-reperfusion injury. Therefore, in this review, we summarized how AMPK regulates autophagic, apoptotic, necroptotic, and ferroptosis pathways in the context of myocardial ischemia-reperfusion injury in the presence and absence of diabetes.

D-pinitol attenuates isoproterenol induced myocardial infarction by alleviating cardiac inflammation, oxidative stress and ultrastructural changes in Swiss Albino mice

Cardiovascular diseases are the most disturbing problems throughout the world. The side effects of existing drugs are continuously compelling the scientist to look for better options in terms of safety, efficacy and cost-effectiveness. Our study is also a move in this direction. We have chosen D-pinitol to see its cardioprotective role in isoproterenol-induced myocardial infarction in Swiss Albino mice. Grouping was made by dividing mice into eight groups (n = 6). Group I - control; Group II - Isoproterenol (ISO) (150 mg/kg, i.p.); Group III - D-pinitol (PIN) (25 mg), Group IV - PIN (50 mg), Group V - PIN (100 mg) per kg per oral, respectively with ISO; Group VI - PIN _{per se} (100 mg D-pinitol only); Group VII - Propranolol (PRO) (20 mg/kg/oral) with ISO; and Group VIII - PRO _{per se} (20 mg/kg, p.o.). After 24 hrs of the last dose, the blood sample was collected for biochemical parameters, then mice were, euthanised through cervical dislocation under anesthesia and cardiac tissue was collected for biochemical, histopathological and ultrastructural evaluation. Administration of ISO in mice altered the level of antioxidant markers, cardiac injury markers and inflammatory markers, which were significantly restored towards normal by D-pinitol at the dose of 50 and 100 mg. 25 mg of D-pinitol dosage, did not produce significant cardio protection. The histopathological and ultrastructural analysis further confirmed these findings. Our study showed that D-pinitol significantly protected myocardial damage which was induced by ISO and reverted oxidative stress and inflammation considerably.

PCSK9 and Other Metabolic Targets to Counteract Ischemia/Reperfusion Injury in Acute Myocardial Infarction and Visceral Vascular Surgery

Ischemia/reperfusion (I/R) injury complicates both unpredictable events (myocardial infarction and stroke) as well as surgically-induced ones when transient clampage of major vessels is needed. Although the main cause of damage is attributed to mitochondrial dysfunction and oxidative stress, the use of antioxidant compounds for protection gave poor results when challenged in clinics. More recently, there is an assumption that, in humans, profound metabolic changes may prevail in driving I/R injury. In the present work, we narrowed the field of search to I/R injury in the heart/brain/kidney axis in acute myocardial infarction, major vascular surgery, and to the current practice of protection in both settings; then, to help the definition of novel strategies to be translated clinically, the most promising metabolic targets with their modulatory compounds—when available—and new preclinical strategies against I/R injury are described. The consideration arisen from the broad range of studies we have reviewed will help to define novel therapeutic approaches to ensure mitochondrial protection, when I/R events are predictable, and to cope with I/R injury, when it occurs unexpectedly.

Magnetic Ligand Fishing Using Immobilized Cyclooxygenase-2 for Identification and Screening of Anticoronary Heart Disease Ligands From Choerospondias axillaris

Inhibition of cyclooxygenase-2 (COX-2) activity is an effective way for treatment of coronary heart disease. And as an important source of COX-2 inhibitors, bioactive compounds of Choerospondias axillaris and pharmacological mechanisms remained lacking in prospective researches. Therefore, for the purpose of accelerating the discovery of natural products targeting designed inhibitors, the COX-2 microreactor composed of functionalized microspheres and magnetic ligand fishing was developed and applied in Choerospondias axillaris, and the physicochemical properties of the COX-2 functionalized microspheres were characterized using Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, the bioactive compounds singled out from ethanol decoction without prepurification were dissociated and identified by ultraperformance liquid chromatography plus Q-Exactive Orbitrap tandem mass spectrometry (UPLC-Q-Exactive Orbitrap-MS/MS). Consequently, 21 bioactive compounds consisting of 6 organic acids, 8 flavonoids, and 7 others were separated and characterized from Choerospondias axillaris, which were reported to participate in the COX-2 inhibitory pathway to varying degrees. Therefore, this method could provide a prospective solution for the extraction and identification of active pharmaceutical ingredients and the rapid screening of some enzyme inhibitors in the complex mixtures.

Cardio-protective effect of tetrahydrocurcumin, the primary hydrogenated metabolite of curcumin in vivo and in vitro: Induction of apoptosis and autophagy via PI3K/AKT/mTOR pathways

Tetrahydrocurcumin (THC) is an essential metabolite of curcumin, a major active component of the Curcuma species, which have been used traditionally for the treatment of cardiovascular diseases. The PI3K/AKT/mTOR signaling pathways serve a vital role during myocardial ischemia-reperfusion (MI/R) injury. The aim of the present study was to investigate the cardioprotective potential and mechanism of THC. In the in vivo study, an animal model of MI/R was induced by coronary occlusion. Results indicated that THC (50 mg/kg/day) protected the rat hearts from MI/R-induced heart failure by increasing ejection fraction (EF) and fractional shortening (FS) and decreasing left ventricular end systolic diameter (LVESD) and left ventricular end systolic volume (LVESV). THC also reduced myocardial infarct size and apoptosis. Furthermore, H9c2 cells were incubated with THC (20 μM) to explore its potential effect following exposure to hypoxia and reoxygenation (H/R). THC post-treatment significantly augmented cell viability and prevented lactate dehydrogenase (LDH) release after H/R exposure. THC effectively improved antioxidant activity by increasing SOD and CAT activities and decreasing MDA level. THC also enhanced mitochondrial membrane potential, inhibited apoptotic cell death, diminished the Bax/Bcl-2 ratio and cleaved caspase-3 level relative to the H/R model. In addition, THC effectively decreased Beclin1 expression and LC3 II/LC3 I ratio, but increased p62 expression, compared with the H/R model group, and decreased the formation of H/R-induced autophagosomes and autolysosomes. Furthermore, THC promoted the phosphorylation of PI3K/AKT/mTOR and induced the expression of hypoxia-inducible factor 1α (HIF-1α) after H/R. However, these effects on H9c2 cells were notably abolished by the PI3K inhibitor LY294002 and mTOR inhibitor rapamycin. In conclusion, THC effectively inhibited H/R-induced autophagy and apoptosis via, at least partially, activating the PI3K/AKT/mTOR pathways. THC might have the potential to be further developed into a potential candidate for the treatment of MI/R injury.

PPARγ Plays an Important Role in Acute Hepatic Ischemia-Reperfusion Injury via AMPK/mTOR Pathway

Background

Hepatic ischemia-reperfusion (IR) injury is one of the severe complications associated with liver surgery and leads to liver dysfunction. PPARγ is always linked with various physiologic pathways, and it can alleviate liver damage in IR injury.

Aim

In this study, we explored the potential mechanism of PPARγ in the pathogenesis of hepatic IR injury by mice model.

Methods

After treated with si-PPARγ or rosiglitazone, mice were subjected to hepatic ischemia-reperfusion. Liver tissue and blood samples were collected to evaluate liver injury and detected relative mRNA and protein expressions.

Results

The expression of PPARγ was increased after reperfusion. And the alleviation of PPARγ aggravated the liver damage in IR; at the same time, upregulation of the expression of PPARγ released the liver damage. And these effects of PPARγ in IR were related to the AMPK/mTOR/autophagy signaling pathway.

Conclusion

PPARγ plays an important role in hepatic IR injury at least partly via the AMPK/mTOR/autophagy pathway.

Metformin protects against insulin resistance induced by high uric acid in cardiomyocytes via AMPK signalling pathways in vitro and in vivo

High uric acid (HUA) is associated with insulin resistance (IR) in cardiomyocytes. We investigated whether metformin protects against HUA-induced IR in cardiomyocytes. We exposed primary cardiomyocytes to HUA, and cellular glucose uptake was quantified by measuring the uptake of 2-NBDG, a fluorescent glucose analog. Western blot was used to examine the levels of signalling protein. Membrane of glucose transporter type 4 (GLUT4) was analysed by immunofluorescence. We monitored the impact of metformin on HUA-induced IR and in myocardial tissue of an acute hyperuricaemia mouse model established by potassium oxonate treatment. Treatment with metformin protected against HUA-reduced glucose uptake induced by insulin in cardiomyocytes. HUA directly inhibited the phosphorylation of Akt and the translocation of GLUT4 induced by insulin, which was blocked by metformin. Metformin promoted phosphorylation of AMP-activated protein kinase (AMPK) and restored the insulin-stimulated glucose uptake in HUA-induced IR cardiomyocytes. As a result of these effects, in a mouse model of acute hyperuricaemia, metformin improved insulin tolerance and glucose tolerance, accompanied by increased AMPK phosphorylation, Akt phosphorylation and translocation of GLUT4 in myocardial tissues. As expected, AICAR, another AMPK activator, had similar effects to metformin, demonstrating the important role of AMPK activation in protecting against IR induced by HUA in cardiomyocytes. Metformin protects against IR induced by HUA in cardiomyocytes and improves insulin tolerance and glucose tolerance in an acute hyperuricaemic mouse model, along with the activation of AMPK. Consequently, metformin may be an important potential new treatment strategy for hyperuricaemia-related cardiovascular disease.

Interaction of Obesity and Hypertension on Cardiac Metabolic Remodeling and Survival Following Myocardial Infarction

Background

Obesity and hypertension are risk factors for myocardial infarction (MI); however, their potential interactions on post‐MI outcomes are unclear. We examined interactions of obesity and hypertensionon post‐MI function, remodeling, metabolic changes, and recovery.

Methods and Results

Male and female C57BL/6J mice were provided standard chow or high‐fat/fructose diet for 8 weeks and then infused with angiotensin II for 2 weeks to induce hypertension. MI was then induced by surgical ligation of the left coronary artery for 7 days. Obesity alone did not cause cardiac injury or exacerbate hypertension‐induced cardiac dysfunction. After MI, however, obese‐normotensive mice had lower survival rates compared with chow‐fed mice (56% versus 89% males; 54% versus 75% females), which were further decreased by hypertension (29% males; and 35% females). Surviving obese‐normotensive males displayed less left ventricular dilation and pulmonary congestion compared with chow‐fed males after MI; hypertension reversed left ventricular dilation because of high‐fat/fructose diet and promoted significant pulmonary congestion compared with chow‐fed controls. Obese‐normotensive males displayed higher left ventricular α‐MHC (alpha‐myosin heavy chain) protein, phosphorylated Akt (protein kinase B) and AMPK (adenosine‐monophosphate activated kinase), PPAR‐γ (peroxisome proliferator activated receptor gamma), and plasma adiponectin levels after MI, indicating favorable contractile and metabolic changes. However, these favorable contractile and metabolic changes were attenuated by hypertension. Obese‐hypertensive males also had lower levels of collagen in the infarcted region, indicating decreased ability to promote an adaptive wound healing response to MI.

Conclusions

Obesity reduces post‐MI survival but is associated with improved post‐MI cardiac function and metabolism in surviving normotensive mice. When hypertension accompanies obesity, favorable metabolic pathways associated with obesity are attenuated and post‐MI cardiac function and remodeling are adversely impacted.

Effects of voluntary exercise duration on myocardial ischaemic tolerance, kinase signaling and gene expression

AIM

Exercise is cardioprotective, though optimal interventions are unclear. We assessed duration dependent effects of exercise on myocardial ischemia-reperfusion (I-R) injury, kinase signaling and gene expression.

METHODS

Responses to brief (2 day; 2EX), intermediate (7 and 14 day; 7EX and 14EX) and extended (28 day; 28EX) voluntary wheel running (VWR) were studied in male C57Bl/6 mice. Cardiac function, I-R tolerance and survival kinase signaling were assessed in perfused hearts.

KEY FINDINGS

Mice progressively increased running distances and intensity, from 2.4 ± 0.2 km/day (0.55 ± 0.04 m/s) at 2-days to 10.6 ± 0.4 km/day (0.72 ± 0.06 m/s) after 28-days. Myocardial mass and contractility were modified at 14-28 days VWR. Cardioprotection was not 'dose-dependent', with I-R tolerance enhanced within 7 days and not further improved with greater VWR duration, volume or intensity. Protection was associated with AKT, ERK1/2 and GSK3β phosphorylation, with phospho-AMPK selectively enhanced with brief VWR. Gene expression was duration-dependent: 7 day VWR up-regulated glycolytic (Pfkm) and down-regulated maladaptive remodeling (Mmp2) genes; 28 day VWR up-regulated caveolar (Cav3), mitochondrial biogenesis (Ppargc1a, Sirt3) and titin (Ttn) genes. Interestingly, I-R tolerance in 2EX/2SED groups improved vs. groups subjected to longer sedentariness, suggesting transient protection on transition to housing with running wheels.

SIGNIFICANCE

Cardioprotection is induced with as little as 7 days VWR, yet not enhanced with further or faster running. This protection is linked to survival kinase phospho-regulation (particularly AKT and ERK1/2), with glycolytic, mitochondrial, caveolar and myofibrillar gene changes potentially contributing. Intriguingly, environmental enrichment may also protect via similar kinase regulation.

SIRT1/SIRT3 Modulates Redox Homeostasis during Ischemia/Reperfusion in the Aging Heart

Ischemia/reperfusion (I/R) injury is the central cause of global death in cardiovascular diseases, which is characterized by disorders such as angina, stroke, and peripheral vascular disease, finally causing severe debilitating diseases and death. The increased rates of morbidity and mortality caused by I/R are parallel with aging. Aging-associated cardiac physiological structural and functional deterioration were found to contribute to abnormal reactive oxygen species (ROS) production during I/R stress. Disturbed redox homeostasis could further trigger the related signaling pathways that lead to cardiac irreversible damages with mitochondria dysfunction and cell death. It is notable that sirtuin proteins are impaired in aged hearts and are critical to maintaining redox homeostasis via regulating substrate metabolism and inflammation and thus preserving cardiac function under stress. This review discussed the cellular and functional alterations upon I/R especially in aging hearts. We propose that mitochondria are the primary source of reactive oxygen species (ROS) that contribute to I/R injury in aged hearts. Then, we highlight the cardiomyocyte protection of the age-related proteins Sirtuin1 (SIRT1) and Sirtuin1 (SIRT3) in response to I/R injury, and we discuss their modulation of cardiac metabolism and the inflammatory reaction that is involved in ROS formation.

CTRP9: An emerging potential anti-aging molecule in brain

C1q/tumor necrosis factor (TNF)-related proteins (CTRPs) particularly CTRP9, have been established to be as adiponectin (APN) highly conserved paralogs which assemble several APN regulatory functions. Recently, growing body of evidences drawn significant attention to evaluate metabolic and cardiovascular effect of CTRP9. However, the potential role of CTRP9 in brain tissue has not yet fully illustrated. Here, we aimed to uncover latest advances regarding the CTRP9 related signaling pathways and during brain aging process.

A review of fibroblast growth factor 21 in diabetic cardiomyopathy

FGF21 (fibroblast growth factor 21) is a regulator of metabolism and performs an important role in glucose and lipid metabolism and the maintenance of energy balance. FGF21 is principally expressed in the liver, but it can also be found in the pancreas, skeletal muscle, and adipose tissue. It is known that levels of serum FGF21 are significantly elevated in obese, insulin-resistant patients, and those with metabolic syndrome. Elevated levels of FGF21 in serum during the early stages of various metabolic diseases are considered a compensatory response by the organism. Therefore, FGF21 is considered a hormone in response to stress and an early diagnostic marker of disease. Diabetic cardiomyopathy is a special type of cardiac complication, characterized as a chronic myocardial disorder caused by diabetes. The pathological process includes increased oxidative stress, energy metabolism in myocardial cells, an inflammatory response, and myocardial cell apoptosis. A growing body of evidence suggests that FGF21 has the potential to be an effective drug for the treatment of diabetic cardiomyopathy. Here, we review recent progress on the characteristics of FGF21 in its protective role, especially in pathological processes such as suppressing apoptosis in the myocardium, reducing inflammation in cardiomyocytes, reducing oxidative stress, and promoting fatty acid oxidation. In addition, we explore the possibility that diabetic cardiomyopathy can be delayed through the application of FGF21, providing possible therapeutic targets of the disease.

Bergenin Exerts Hepatoprotective Effects by Inhibiting the Release of Inflammatory Factors, Apoptosis and Autophagy via the PPAR-γ Pathway

Objective

Hepatic ischemia reperfusion (IR) limits the development of liver transplantation technology. The aim of this study was to explore the protective effects of Bergenin on hepatic IR, particularly the elimination of reactive oxygen species (ROS) and activation of the peroxisome proliferators activated receptor γ (PPAR-γ) pathway.

Methods

Initial experiments were performed to confirm the non-toxicity of Bergenin. Mice were randomly divided into sham, IR, and IR + Bergenin (10, 20 and 40 mg/kg) groups, and serum and tissue samples were obtained at 2, 8 and 24 h for detection of liver enzymes (ALT and AST), inflammatory factors (TNF-α, IL-6 and IL-1β), ROS, cell death markers (Bcl-2, Bax, Beclin-1 and LC3) and related important pathways (PPAR-γ, P38 MAPK, NF-κB p65 and JAK2/STAT1).

Results

Bergenin reduced the release of ROS, down-regulated inflammatory factors, and inhibited apoptosis and autophagy. Additionally, expression of PPAR-γ-related genes was increased and phosphorylation of P38 MAPK, NF-κB p65 and JAK2/STAT1-related proteins was decreased in Bergenin pre-treatment groups in a dose-dependent manner.

Conclusion

Bergenin exerts hepatic protection by eliminating ROS, affecting the release of inflammatory factors, and influencing apoptosis- and autophagy-related genes via the PPAR-γ pathway in this model of hepatic IR injury.

Integrative Analysis of Expression Profiles of MicroRNAs and mRNAs in Treatment of Acute Myocardial Infarction with Compound Longmaining Decoction

BACKGROUND This study identified microRNAs (miRNAs) and mRNAs associated with Compound Longmaining (CLMN) treatment of acute myocardial infarction (AMI). Our results provide a theoretical framework to guide AMI treatment and improve myocardial injury. MATERIAL AND METHODS The myocardial tissues of the sham operation group (S), the model group (M), and the CLMN treatment group (T) were obtained. The mRNA and miRNA expression profiles were identified using RNA-sequencing analysis. The sequencing results were verified by quantitative real-time PCR (qRT-PCR). Bioinformatics was used to predict the function of differentially expressed genes (DEGs) and related signal transduction pathways. The target genes of miRNAs were predicted by software analysis, and the relationship between miRNA and mRNA was studied by network analysis. RESULTS RNA-sequencing revealed 22 differentially expressed miRNAs (DEMs) and 76 DEGs in myocardial tissue. Six DEMs and 9 DEGs were randomly selected for qRT-PCR validation, and corroborating results were obtained. The results of Gene ontology (GO) showed that DEGs participated in different biological processes. Through the combined analysis of miRNAs and mRNAs expression, it was confirmed that a single miRNA is involved in the regulation of multiple genes, and also multiple miRNAs can target one gene. CONCLUSIONS The analysis based on the miRNA-mRNA network can not only help to elucidate the potential molecular mechanism of CLMN treatment of AMI, but can also help in identifying novel therapeutic targets.

Sphingolipid Synthesis Inhibition by Myriocin Administration Enhances Lipid Consumption and Ameliorates Lipid Response to Myocardial Ischemia Reperfusion Injury

Myocardial infarct requires prompt thrombolytic therapy or primary percutaneous coronary intervention to limit the extent of necrosis, but reperfusion creates additional damage. Along with reperfusion, a maladaptive remodeling phase might occur and it is often associated with inflammation, oxidative stress, as well as a reduced ability to recover metabolism homeostasis. Infarcted individuals can exhibit reduced lipid turnover and their accumulation in cardiomyocytes, which is linked to a deregulation of peroxisome proliferator activated receptors (PPARs), controlling fatty acids metabolism, energy production, and the anti-inflammatory response. We previously demonstrated that Myriocin can be effectively used as post-conditioning therapeutic to limit ischemia/reperfusion-induced inflammation, oxidative stress, and infarct size, in a murine model. In this follow-up study, we demonstrate that Myriocin has a critical regulatory role in cardiac remodeling and energy production, by up-regulating the transcriptional factor EB, PPARs nuclear receptors and genes involved in fatty acids metabolism, such as VLDL receptor, Fatp1, CD36, Fabp3, Cpts, and mitochondrial FA dehydrogenases. The overall effects are represented by an increased β–oxidation, together with an improved electron transport chain and energy production. The potent immunomodulatory and metabolism regulatory effects of Myriocin elicit the molecule as a promising pharmacological tool for post-conditioning therapy of myocardial ischemia/reperfusion injury.

MicroRNA-370 protects against myocardial ischemia/reperfusion injury in mice following sevoflurane anesthetic preconditioning through PLIN5-dependent PPAR signaling pathway

Myocardial ischemia/reperfusion injury (IRI) has long been identified to be a contributor to adverse cardiovascular outcomes following myocardial ischemia, cardiac surgery or circulatory arrest. This study aims to investigate the effects of microRNA (miR-370) targeting perilipin-5 (PLIN5) in mice following sevoflurane anesthetic preconditioning (SAP). A mouse model of left ventricular myocardial IRI was established, followed by the evaluation of myocardial infarction size and cardiac function to determine the effects of SAP. The underlying regulatory mechanisms of miR-370 were analyzed in concert with the treatment of miR-370 mimic, miR-370 inhibitor, or siRNA against PLIN5 in cardiomyocytes isolated from mice with IRI. Also, cardiomyocyte proliferation, cell cycle distribution and apoptosis were evaluated following treatment. Lastly, SAP-treated I/R mice were injected with miR-370 inhibitor to verify the mechanism of SAP. The use of SAP conferred cardioprotective effects on myocardial IRI. MiR-370 was downregulated in mice that exhibited IRI, but SAP elevated the miR-370 expression. Functionally, miR-370 negatively targeted PLIN5 and activated the peroxisome proliferator activated-receptor (PPAR) signaling pathway, leading to decreased PPARγ expression but increased PPARα expression. The results also showed that elevation of miR-370 or the silencing of PLIN5 promoted cardiomyocyte proliferation. miR-370 also inhibited cardiomyocyte apoptosis as reflected by decreased caspase-3 expression and increased Bcl-2 expression. Additionally, SAP also alleviated I/R injury by inhibiting PPARγ. This study demonstrates that SAP induces miR-370 and exerts cardioprotective effects on myocardial IRI, where upregulation of miR-370 alleviates myocardial IRI via inhibiting the PLIN5-dependent PPAR signaling pathway.

6-Gingerol Protects Heart by Suppressing Myocardial Ischemia/Reperfusion Induced Inflammation via the PI3K/Akt-Dependent Mechanism in Rats

Our previous study has demonstrated that 6-Gingerol (6-G) could alleviate myocardial ischemia/reperfusion injury (MIRI). However, the molecular mechanism underlying the process of myocardial ischemia/reperfusion (I/R) injury alleviation by 6-G remains unelucidated. The objective of the present study is to further investigate the potential mechanism for 6-G to alleviate MIRI in rats. Thirty-two Sprague-Dawley rats were randomly divided into four groups: the Sham group, the I/R group, the 6-G + I/R group, and the LY294002 (LY) + 6-G + I/R group. For the rats in each of the groups, data were collected for cardiogram, cardiac function, area of myocardial infarction, myocardial pathology, myocardial enzyme, marker of inflammatory response, and PI3K/Akt signaling pathway. We found that the pretreatment of 6-G with 6 mg/kg could shrink the ST section of cardiogram, improve the cardiac function, reduce the area of myocardial infarction and the degree of cardiac pathological injury, lower the level of myocardial enzyme, and inhibit the inflammatory response. In addition, our results also indicated that 6-G could upregulate the expression of PI3K and p-Akt and that LY294002, a blocking agent of PI3K/Akt signaling pathway, could nullify the protecting role of 6-G. Our experimental results showed that 6-G could inhibit I/R-induced inflammatory response through the activation of the PI3K/Akt signaling pathway.

LXR/RXR signaling and neutrophil phenotype following myocardial infarction classify sex differences in remodeling

Sex differences in heart failure development following myocardial infarction (MI) are not fully understood. We hypothesized that differential MI signaling could explain variations in outcomes. Analysis of the mouse heart attack research tool 1.0 (422 mice; young = 5.4 ± 0.1; old = 23.3 ± 0.1 months of age) was used to dissect MI signaling pathways, which was validated in a new cohort of mice (4.8 ± 0.2 months of age); and substantiated in humans. Plasma collected at visit 2 from the MI subset of the Jackson Heart Study (JHS; a community-based study consisting of middle aged and older adults of African ancestry) underwent glycoproteomics grouped by outcome: (1) heart failure hospitalization after visit 2 (n = 3 men/12 women) and (2) without hospitalization through 2012 (n = 24 men/21 women). Compared to young male mice, the infarct region of young females had fewer, but more efficient tissue clearing neutrophils with reduced pro-inflammatory gene expression. Apolipoprotein (Apo) F, which acts upstream of the liver X receptors/retinoid X receptor (LXR/RXR) pathway, was elevated in the day 7 infarcts of old mice compared to young controls and was increased in both men and women with heart failure. In vitro, Apo F stimulated CD36 and peroxisome proliferator-activated receptor (PPAR)γ activation in male neutrophils to turn off NF-κB activation and stimulate LXR/RXR signaling to initiate resolution. Female neutrophils were desensitized to Apo F and instead relied on thrombospondin-1 stimulation of CD36 to upregulate AMP-activated protein kinase, resulting in an overall better wound healing strategy. With age, female mice were desensitized to LXR/RXR signaling, resulting in enhanced interleukin-6 activation, a finding replicated in the JHS community cohort. This is the first report to uncover sex differences in post-MI neutrophil signaling that yielded better outcomes in young females and worse outcomes with age.

Activation of AMPK inhibits inflammatory response during hypoxia and reoxygenation through modulating JNK-mediated NF-κB pathway

BACKGROUND

AMP-activated Protein Kinase (AMPK) is a stress-activated kinase that protects against cardiomyocyte injury during ischemia and reperfusion. c-Jun N-terminal kinase (JNK), a mitogen activated protein kinase, is activated by ischemia and reperfusion. NF-κB is an important transcription factor involved in ischemia and reperfusion injury.

METHODS AND RESULTS

The intrinsic activation of AMPK attenuates the inflammation which occurred during ischemia/reperfusion through the modulation of the JNK mediated NF-κB signaling pathway. Rat cardiac myoblast H9c2 cells were subjected to hypoxia and/or reoxygenation to investigate the signal transduction that occurred during myocardial ischemia/reperfusion. Mitochondrial function was measured by the Seahorse XF24 V7 PS system. Hypoxia treatment triggered AMPK activation in H9c2 cells in a time dependent manner. The inhibition of hypoxic AMPK activation through a pharmacological approach (Compound C) or siRNA knockdown of AMPK α catalytic subunits caused dramatic augmentation in JNK activation, inflammatory NF-κB phosphorylation, and apoptosis during hypoxia and reoxygenation. Inhibition of AMPK activation significantly impaired mitochondrial function and increased the generation of reactive oxygen species (ROS) during hypoxia and reoxygenation. In contrast, pharmacological activation of AMPK by metformin significantly inhibited mitochondrial permeability transition pore (mPTP) opening and ROS generation. Moreover, AMPK activation significantly attenuated the JNK-NF-κB signaling cascade and inhibited mRNA and protein levels of pro-inflammatory cytokines, such as TNF-α and IL-6, during hyopoxia/reoxygenation in H9c2 cells. Intriguingly, both pharmacologic inhibition of JNK by JNK-IN-8 and siRNA knockdown of JNK signaling pathway attenuated NF-κB phosphorylation and apoptosis but did not affect AMPK activation in response to hypoxia and reoxygenation.

CONCLUSIONS

AMPK activation modulates JNK-NF-κB signaling cascade during hypoxia and reoxygenation stress conditions. Cardiac AMPK activation plays a critical role in maintaining mitochondrial function and inhibiting the inflammatory response caused by ischemic insults.

Fibroblast growth factor 19 protects the heart from oxidative stress-induced diabetic cardiomyopathy via activation of AMPK/Nrf2/HO-1 pathway

Diabetes affects cardiac structure and function, where it leads to diabetic cardiomyopathy. Reactive oxygen species (ROS) produced by oxidative stress play an important role in the development of diabetic cardiomyopathy. Fibroblast growth factor (FGF) 19, an enterokine, is synthesized and released into the ileum. In the present study, we revealed that FGF19 induced an antioxidant response through stimulating the expression of nuclear erythroid factor 2 (NE-F2)-related factor 2 (Nrf2) and as well as reducing ROS production through the AMPK signaling pathway. Additionally, AMPK inhibition by the AMPK-specific inhibitor compound C decreased Nrf2 and heme oxygenase-1 (HO-1) protein expression. Taken together, these results suggested that FGF19, through the anti-oxidative defense system, attenuated the development of diabetic cardiomyopathy and restored cardiac function.

Effects of microRNA-292-5p on myocardial ischemia-reperfusion injury through the peroxisome proliferator-activated receptor-α/-γ signaling pathway

Ischemia-reperfusion injury (IRI) is a major cause of cardiac damage following various pathological processes, such as free radical damage and cell apoptosis. This study aims to investigate whether microRNA-292-5p (miR-292-5p) protects against myocardial ischemia-reperfusion injury (IRI) via the peroxisome proliferator-activated receptor (PPAR)-α/-γ signaling pathway in myocardial IRI mice models. Mouse models of myocardial IRI were established. Adult male C57BL/6 mice were divided into different groups. The hemodynamic indexes, levels of related inflammatory factors and serum myocardial enzymes, and malondialdehyde (MDA) content and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were detected. The 2,3,5-triphenyltetrazolium chloride (TTC) staining was applied to determine infarct size. TUNEL staining was used to detect cardiomyocyte apoptosis. RT-qPCR and western blotting were performed to measure the related gene expressions. Compared with the model group and the T0070907 + miR-292-5p inhibitor, the miR-292-5p inhibitor group exhibited decreased incidence and duration time of ventricular tachycardia and ventricular fibrillation, serum myocardial enzymes, TNF-α, IL-6, IL-1β, MDA, cardiomyocyte apoptosis, expressions of Bax and p53 in addition to increased SOD and GSH-Px activity, and increased expressions of Bcl-2, PPARα, PPARγ, PLIN5, AQP7, and PCK1. The T0070907 group exhibited opposite results compared to the miR-292-5p inhibitor group. The results indicate that miR-292-5p downregulation protects against myocardial IRI through activation of the PPAR-α/PPAR-γ signaling pathway.

The cardioprotective effect of dihydromyricetin prevents ischemia-reperfusion-induced apoptosis in vivo and in vitro via the PI3K/Akt and HIF-1α signaling pathways

Reperfusion therapy is widely used to treat acute myocardial infarction (AMI). However, further injury to the heart induced by rapidly initiating reperfusion is often encountered in clinical practice. A lack of pharmacological strategies in clinics limits the prognosis of patients with myocardial ischemia-reperfusion injury (MIRI). Dihydromyricetin (DMY) is one of the most abundant components in vine tea, commonly known as the tender stems and leaves of Ampelopsis grossedentata. The aim of this study was to evaluate the cardioprotection of DMY against myocardial ischemia-reperfusion (I/R) injury and to further investigate the underlying mechanism. An I/R injury was induced by left anterior descending coronary artery occlusion in adult male rats in vivo and a hypoxia-reoxygenation (H/R) injury in H9c2 cardiomyocytes in vitro. We found that DMY pretreatment provided significant protection against I/R-induced injury, including enhanced antioxidant capacity and inhibited apoptosis in vivo and in vitro. This effect correlated with the activation of the PI3K/Akt and HIF-1α signaling pathways. Conversely, blocking Akt activation with the PI3K inhibitor LY294002 effectively suppressed the protective effects of DMY against I/R-induced injury. In addition, the PI3K inhibitor partially blocked the effects of DMY on the upregulation of Bcl-2, Bcl-xl, procaspase-3, -8, and -9 protein expression and the downregulation of HIF-1α, Bnip3, Bax, Cyt-c, cleaved caspase-3, -8, and -9 protein expression. Collectively, these results showed that DMY decreased the apoptosis and necrosis by I/R treatment, and PI3K/Akt and HIF-1α plays a crucial role in protection during this process. These observations indicate that DMY has the potential to exert cardioprotective effects against I/R injury and the results might be important for the clinical efficacy of AMI treatment.

Activated protein C protects against pressure overload-induced hypertrophy through AMPK signaling

We found that the anticoagulant plasma protease, activated protein C (APC), stimulates the energy sensor kinase, AMPK, in the stressed heart by activating protease-activated receptor 1 (PAR1) on cardiomyocytes. Wild-type (WT) and AMPK-kinase dead (KD) transgenic mice were subjected to transverse aortic constriction (TAC) surgery. The results demonstrated that while no phenotypic differences can be observed between WT and AMPK-KD mice under normal physiological conditions, AMPK-KD mice exhibit significantly larger hearts after 4 weeks of TAC surgery. Analysis by echocardiography suggested that the impairment in the cardiac function of AMPK-KD hearts is significantly greater than that of WT hearts. Immunohistochemical staining revealed increased macrophage infiltration and ROS generation in AMPK-KD hearts after 4 weeks of TAC surgery. Immunoblotting results demonstrated that the redox markers, pShc⁶⁶, 4-hydroxynonenal and ERK, were all up-regulated at a higher extent in AMPK-KD hearts after 4 weeks of TAC surgery. Administration of APC-WT and the signaling selective APC-2Cys mutant, but not the anticoagulant selective APC-E170A mutant, significantly attenuated pressure overload-induced hypertrophy and fibrosis. Macrophage infiltration and pShc⁶⁶ activation caused by pressure overload were also inhibited by APC and APC-2Cys but not by APC-E170A. Therefore, the cardiac AMPK protects against pressure overload-induced hypertrophy and the signaling selective APC-2Cys may have therapeutic potential for treating hypertension-related hypertrophy without increasing the risk of bleeding.

How AMPK and PKA Interplay to Regulate Mitochondrial Function and Survival in Models of Ischemia and Diabetes

Adenosine monophosphate-activated protein kinase (AMPK) is a conserved, redox-activated master regulator of cell metabolism. In the presence of oxidative stress, AMPK promotes cytoprotection by enhancing the conservation of energy by suppressing protein translation and by stimulating autophagy. AMPK interplays with protein kinase A (PKA) to regulate oxidative stress, mitochondrial function, and cell survival. AMPK and dual-specificity A-kinase anchoring protein 1 (D-AKAP1), a mitochondrial-directed scaffold of PKA, interact to regulate mitochondrial function and oxidative stress in cardiac and endothelial cells. Ischemia and diabetes, a chronic disease that increases the onset of cardiovascular diseases, suppress the cardioprotective effects of AMPK and PKA. Here, we review the molecular mechanisms by which AMPK and D-AKAP1/PKA interplay to regulate mitochondrial function, oxidative stress, and signaling pathways that prime endothelial cells, cardiac cells, and neurons for cytoprotection against oxidative stress. We discuss recent literature showing how temporal dynamics and localization of activated AMPK and PKA holoenzymes play a crucial role in governing cellular bioenergetics and cell survival in models of ischemia, cardiovascular diseases, and diabetes. Finally, we propose therapeutic strategies that tout localized PKA and AMPK signaling to reverse mitochondrial dysfunction, oxidative stress, and death of neurons and cardiac and endothelial cells during ischemia and diabetes.

The structure-activity relationship of ginsenosides on hypoxia-reoxygenation induced apoptosis of cardiomyocytes

Ginsenosides have been studied extensively in recent years due to their therapeutic effects in cardiovascular diseases. While most studies examined the different ginsenosides individually, few studies compare the therapeutic effects among the different types. This study examined how effective protopanaxadiol, protopanaxatriol ginsenosides Rh2, Rg3, Rh1, and Rg2 of the ginsenoside family are in protecting H9c2 cardiomyocytes from damage caused by hypoxia/reoxygenation. In the current study, a model of myocardial ischemia and reperfusion was induced in H9c2 cardiomyocytes by oxygen deprivation via a hypoxia chamber followed by reoxygenation. Our data show that structures similar to that of protopanaxadiol, which lacked the hydroxide group at C6, were more effective in lowering apoptosis than structures similar to protopanaxatriol with a hydroxide group at C6. As the compounds increased in size and complexity, the cardioprotective effects diminished. In addition, the S enantiomer proved to be more effective in cardioprotection than the R enantiomer. Furthermore, the immunoblotting analysis demonstrated that ginsenosides activate AMPK but suppress JNK signaling pathways during hypoxia/reoxygenation. Thus, ginsenosides treatment attenuated hypoxia/reoxygenation-induced apoptosis via modulating cardioprotective AMPK and inflammation-related JNK signaling pathways.

Sestrin2 prevents age-related intolerance to ischemia and reperfusion injury by modulating substrate metabolism

A novel stress-inducible protein, Sestrin2 (Sesn2), declines in the heart with aging. AMPK has emerged as a pertinent stress-activated kinase that has been shown to have cardioprotective capabilities against myocardial ischemic injury. We identified the interaction between Sesn2 and AMPK in the ischemic heart. To determine whether ischemic AMPK activation-modulated by the Sesn2-AMPK complex in the heart-is impaired in aging that sensitizes the heart to ischemic insults, young C57BL/6 mice (age 3-4 mo), middle-aged mice (age 10-12 mo), and aged mice (age 24-26 mo) were subjected to left anterior descending coronary artery occlusion for in vivo regional ischemia. The ex vivo working heart system was used for measuring substrate metabolism. The protein level of Sesn2 in hearts was gradually decreased with aging. Of interest, ischemic AMPK activation was blunted in aged hearts compared with young hearts (P < 0.05); the AMPK downstream glucose uptake and the rate of glucose oxidation were significantly impaired in aged hearts during ischemia and reperfusion (P < 0.05 vs. young hearts). Myocardial infarction size was larger in aged hearts (P < 0.05 vs. young hearts). Immunoprecipitation with Sesn2 Ab revealed that cardiac Sesn2 forms a complex with AMPK and upstream liver kinase B1 (LKB1) during ischemia. Of interest, the binding affinity between Sesn2 and AMPK upstream LKB1 is impaired in aged hearts during ischemia (P < 0.05 vs. young hearts). Furthermore, Sesn2-knockout hearts demonstrate a cardiac phenotype and response to ischemic stress that is similar to wild-type aged hearts (i.e., impaired ischemic AMPK activation and higher sensitivity to ischemia- and reperfusion- induced injury). Adeno-associated virus-Sesn2 was delivered to aged hearts via a coronary delivery approach and significantly rescued the protein level of Sesn2 and the ischemic tolerance of aged hearts; therefore, Sesn2 is a scaffold protein that mediates AMPK activation in the ischemic myocardium via an interaction with AMPK upstream LKB1. Decreased Sesn2 levels in aging lead to a blunted ischemic AMPK activation, alterations in substrate metabolism, and an increased sensitivity to ischemic insults-Quan, N., Sun, W., Wang, L., Chen, X., Bogan, J. S., Zhou, X., Cates, C., Liu, Q., Zheng, Y., Li J. Sestrin2 prevents age-related intolerance to ischemia and reperfusion injury by modulating substrate metabolism.

Phenol-enriched olive oils modify paraoxonase-related variables: A randomized, crossover, controlled trial

SCOPE

Low paraoxonase (PON)1 activities, and high PON1 and low PON3 protein levels are characteristic of cardiovascular disease. Our aim was to assess short- and long-term effects of virgin olive oils (VOO), enriched with their own phenolic compounds (PC; FVOO) or with them plus complementary PC from thyme (FVOOT), on PON-related variables and the mechanisms involved.

METHODS AND RESULTS

Two randomized, controlled, double-blind, and crossover interventions were conducted. In an acute intake study, participants ingested three FVOOs differing in PC content. In a sustained intake study, participants ingested a control VOO and two different FVOOs with the same PC content but differing in PC source. Acute and sustained intake of VOO and FVOO decreased PON1 protein and increased PON1-associated specific activities, while FVOOT yielded opposite results. PON3 protein levels increased only after sustained consumption of VOO. Mechanistic studies performed in rat livers showed that intake of isolated PC from VOO and from thyme modulate mitogen-activated protein kinases and peroxisome proliferator-activated receptors regulating PON synthesis, while a combination of these PCs cancels such regulation.

CONCLUSION

This study reveals that the intake of phenol-enriched FVOOs modulates oxidative balance by modifying PON-related variables according to PC content and source, and this modulation can be perceived as beneficial.

FGF21 ameliorates diabetic cardiomyopathy by activating the AMPK-paraoxonase 1 signaling axis in mice

The aim of the present study is to explore the molecular mechanism of fibroblast growth factor 21 (FGF21) in protecting against diabetic cardiomyopathy (DCM). Streptozotocin/high-fat diet (STZ/HFD) was used to induced diabetes in FGF21-deficient mice and their wild-type littermates, followed by evaluation of the difference in DCM between the two genotypes. Primary cultured cardiomyocytes were also used to explore the potential molecular mechanism of FGF21 in the protection of high glucose (HG)-induced cardiomyocyte injury. STZ/HFD-induced cardiomyopathy was exacerbated in FGF21 knockout mice, which was accompanied by a significant reduction in cardiac AMP-activated protein kinase (AMPK) activity and paraoxonase 1 (PON1) expression. By contrast, adeno-associated virus (AAV)-mediated overexpression of FGF21 in STZ/HFD-induced diabetic mice significantly enhanced cardiac AMPK activity, PON1 expression and its biological activity, resulting in alleviated DCM. In cultured cardiomyocytes, treatment with recombinant mouse FGF21 (rmFGF21) counteracted HG-induced oxidative stress, mitochondrial dysfunction, and inflammatory responses, leading to increased AMPK activity and PON1 expression. However, these beneficial effects of FGF21 were markedly weakened by genetic blockage of AMPK or PON1. Furthermore, inactivation of AMPK also markedly blunted FGF21-induced PON1 expression but significantly increased HG-induced cytotoxicity in cardiomyocytes, the latter of which was largely reversed by adenovirus-mediated PON1 overexpression. These findings suggest that FGF21 ameliorates DCM in part by activation of the AMPK-PON1 axis.

Cardioprotection by combination of three compounds from ShengMai preparations in mice with myocardial ischemia/reperfusion injury through AMPK activation-mediated mitochondrial fission

GRS is a drug combination of three active components including ginsenoside Rb1, ruscogenin and schisandrin. It derived from the well-known TCM formula ShengMai preparations, a widely used traditional Chinese medicine for the treatment of cardiovascular diseases in clinic. The present study explores the cardioprotective effects of GRS on myocardial ischemia/reperfusion (MI/R) injury compared with ShengMai preparations and investigates the underlying mechanisms. GRS treatment significantly attenuated MI/R injury and exhibited similar efficacy as Shengmai preparations, as evidenced by decreased myocardium infarct size, ameliorated histological features, the decrease of LDH production and improved cardiac function, and also produced a significant decrease of apoptotic index. Mechanistically, GRS alleviated myocardial apoptosis by inhibiting the mitochondrial mediated apoptosis pathway as reflected by inhibition of caspase-3 activity, normalization of Bcl-2/Bax levels and improved mitochondrial function. Moreover, GRS prevented cardiomyocytes mitochondrial fission and upregulated AMPKα phosphorylation. Interestingly, AMPK activation prevented hypoxia and reoxygenation induced mitochondrial fission in cardiomyocytes and GRS actions were significantly attenuated by knockdown of AMPKα. Collectively, these data show that GRS is effective in mitigating MI/R injury by suppressing mitochondrial mediated apoptosis and modulating AMPK activation-mediated mitochondrial fission, thereby providing a rationale for future clinical applications and potential therapeutic strategy for MI/R injury.

A Metabolic Inhibitory Cocktail for Grave Cancers: Metformin, Pioglitazone and Lithium Combination in Treatment of Pancreatic Cancer and Glioblastoma Multiforme

Pancreatic cancer (PC) and glioblastoma multiforme (GBM) are among the human cancers with worst prognosis which require an urgent need for efficient therapies. Here, we propose to apply to treat both malignancies with a triple combination of drugs, which are already in use for different indications. Recent studies demonstrated a considerable link between risk of PC and diabetes. In experimental models, anti-diabetogenic agents suppress growth of PC, including metformin (M), pioglitazone (P) and lithium (L). L is used in psychiatric practice, yet also bears anti-diabetic potential and selectively inhibits glycogen synthase kinase-3 beta (GSK-3β). M, a biguanide class anti-diabetic agent shows anticancer activity via activating AMP-activated protein kinase (AMPK). Glitazones bind to PPAR-γ and inhibit NF-κB, triggering cell proliferation, apoptosis resistance and synthesis of inflammatory cytokines in cancer cells. Inhibition of inflammatory cytokines could simultaneously decrease tumor growth and alleviate cancer cachexia, having a major role in PC mortality. Furthermore, mutual synergistic interactions exist between PPAR-γ and GSK-3β, between AMPK and GSK-3β and between AMPK and PPAR-γ. In GBM, M blocks angiogenesis and migration in experimental models. Very noteworthy, among GBM patients with type 2 diabetes, usage of M significantly correlates with better survival while reverse is true for sulfonylureas. In experimental models, P synergies with ligands of RAR, RXR and statins in reducing growth of GBM. Further, usage of P was found to be lesser in anaplastic astrocytoma and GBM patients, indicating a protective effect of P against high-grade gliomas. L is accumulated in GBM cells faster and higher than in neuroblastoma cells, and its levels further increase with chronic exposure. Recent studies revealed anti-invasive potential of L in GBM cell lines. Here, we propose that a triple-agent regime including drugs already in clinical usage may provide a metabolic adjuvant therapy for PC and GBM.

The cardiovascular impact of visfatin - an inflammation predictor biomarker in metabolic syndrome

As it had been already stated by latest research, inflammation is a condition which sits at the very base of atherogenesis, which is the major consequence of the metabolic syndrome. It was stated that adipose tissue impacts all organs by the synthesis of adipokines. Visfatin/NAMPT is a biomarker that was recently discovered in mice (2005). In the beginning it was believed to have insulin-like properties, but afterwards research has found important links between Visfatin and inflammation, endothelial dysfunction and atherosclerosis in coronary artery disease. It was also linked to plaque instability in acute coronary syndromes. More studies are needed though, to clearly state whether Visfatin/NAMPT has a positive or negative role because, up until now, the only sure fact is that its serum levels correlate with the presence of an inflammatory state.

Cardiac-Specific Deletion of the Pdha1 Gene Sensitizes Heart to Toxicological Actions of Ischemic Stress

Pyruvate dehydrogenase (PDH) plays a key role in aerobic energy metabolism and occupies a central crossroad between glycolysis and the tricarboxylic acid cycle. We generated inducible cardiac-specific PDH E1α knockout (CreER(T2)-PDH(flox/flox)) mice that demonstrated a high mortality rate. It was hypothesized that PDH modulating cardiac glucose metabolism is crucial for heart functions under normal physiological and/or stress conditions. The myocardial infarction was conducted by a ligation of the left anterior descending coronary arteries. Cardiac PDH E1α deficiency caused large myocardial infarcts size and macrophage infiltration in the hearts (P < .01 vs wild-type [WT]). Wheat germ agglutinin and Masson trichrome staining revealed significantly increased hypertrophy and fibrosis in PDH E1α-deficient hearts (P < .05 vs WT). Measurements of heart substrate metabolism in an ex vivo working heart perfusion system demonstrated a significant impairment of glucose oxidation in PDH E1α-deficient hearts during ischemia/reperfusion (P < .05 vs WT). Dichloroacetate, a PDH activator, increased glucose oxidation in WT hearts during ischemia/reperfusion and reduced myocardial infarct size in WT, but not in PDH E1α-deficient hearts. Immunoblotting results demonstrated that cardiac PDH E1α deficiency leads to an impaired ischemic AMP-activated protein kinase activation through Sestrin2-liver kinase B1 interaction which is responsible for an increased susceptibility of PDH E1α-deficient heart to ischemic insults. Thus, cardiac PDH E1α deficiency impairs ischemic AMP-activated protein kinase signaling and sensitizes hearts to the toxicological actions of ischemic stress.

The protective effect of trimetazidine on myocardial ischemia/reperfusion injury through activating AMPK and ERK signaling pathway

INTRODUCTION

Trimetazidine (TMZ) is an anti-anginal drug that has been widely used in Europe and Asia. The TMZ can optimize energy metabolism via inhibition of long-chain 3-ketoacyl CoA thiolase (3-KAT) in the heart, with subsequent decrease in fatty acid oxidation and stimulation of glucose oxidation. However, the mechanism by which TMZ aids in cardioprotection against ischemic injury has not been characterized. AMP-activated protein kinase (AMPK) is an energy sensor that controls ATP supply from substrate metabolism and protects heart from energy stress. TMZ changes the cardiac AMP/ATP ratio by modulating fatty acid oxidation, thereby triggering AMPK signaling cascade that contributes to the protection of the heart from ischemia/reperfusion (I/R) injury.

METHODS

The mouse model of in vivo regional ischemia and reperfusion by the ligation of the left anterior descending coronary artery (LAD) was used for determination of myocardial infarction. The infarct size was compared between C57BL/6J WT mice and AMPK kinase dead (KD) transgenic mice with or without TMZ treatment. The ex vivo working heart perfusion system was used to monitor the effect of TMZ on glucose oxidation and fatty acid oxidation in the heart.

RESULTS

TMZ treatment significantly stimulates cardiac AMPK and extracellular signal-regulated kinase (ERK) signaling pathways (p<0.05 vs. vehicle group). The administration of TMZ reduces myocardial infarction size in WT C57BL/6J hearts, the reduction of myocardial infarction size by TMZ in AMPK KD hearts was significantly impaired versus WT hearts (p<0.05). Intriguingly, the administration of ERK inhibitor, PD98059, to AMPK KD mice abolished the cardioprotection of TMZ against I/R injury. The ex vivo working heart perfusion data demonstrated that TMZ treatment significantly activates AMPK signaling and modulating the substrate metabolism by shifting fatty acid oxidation to glucose oxidation during reperfusion, leading to reduction of oxidative stress in the I/R hearts. Therefore, both AMPK and ERK signaling pathways mediate the cardioprotection of TMZ against ischemic injury. The metabolic benefits of TMZ for angina patients could be due to the activation of energy sensor AMPK in the heart by TMZ administration.

The Modulation of Cardiac Contractile Function by the Pharmacological and Toxicological Effects of Urocortin2

Urocortin2 (Ucn2) has been revealed to enhance cardiac function in heart failure. However, the pharmacological and toxicological effects of Ucn2 on cardiomyocytes are incompletely understood. In this study, we investigated the possible mechanisms of Ucn2 on mediating the contractility of cardiomyocytes. Mechanical properties and intracellular Ca(2+) properties were measured in isolated cardiomyocytes from different treatment groups. The stress signaling was evaluated using Western blot. The results demonstrated that Ucn2 induced maximal velocity of shortening (+dL/dt), peak height, peak shortening (PS) amplitude, maximal velocity of relengthening (-dL/dt), accompanied by a significant rise in intracellular Ca(2+) level and a fall of the mean time constant of Ca(2+) transient decay (Tau) in WT cardiomyocytes. However, these effects were abolished by preincubation of type 2 CRF receptors (CRFR2) antagonist anti-sauvagine 30 (a-SVG-30). We also found that Ucn2 treatment activated the AMPK pathway in isolated cardiomyocytes via CRFR2. Furthermore, Ucn2 induced protein kinase A (PKA) and phospholamban (PLN) phosphorylation. Pretreatment of PKA inhibitor H89 reduced the inotropic and lusitropic effects of Ucn2 as well as decreased the intracellular Ca(2+) load and slowed down the Ca(2+) transient decay. We also showed that preincubation of Compound C, an inhibitor of AMPK, inhibited the phosphorylation of PKA and the intracellular Ca(2+) level in cardiomyocytes without affecting the contractile function and the Tau of cardiomyocytes. Taken together, it suggests that Ucn2 facilitate the contractility of cardiomyocytes via activating both AMPK and PKA.

Lysophosphatidic acid enhances survival of human CD34(+) cells in ischemic conditions

Several clinical trials are exploring therapeutic effect of human CD34⁺ cells in ischemic diseases, including myocardial infarction. Unfortunately, most of the cells die few days after delivery. Herein we show that lysophosphatidic acid (LPA)-treated human umbilical cord blood-derived CD34⁺ cells cultured under hypoxic and serum-deprived conditions present 2.2-fold and 1.3-fold higher survival relatively to non-treated cells and prostaglandin E₂-treated cells, respectively. The pro-survival effect of LPA is concentration- and time-dependent and it is mediated by the activation of peroxisome proliferator-activator receptor γ (PPARγ) and downstream, by the activation of pro-survival ERK and Akt signaling pathways and the inhibition of mitochondrial apoptotic pathway. In hypoxia and serum-deprived culture conditions, LPA induces CD34⁺ cell proliferation without maintaining the their undifferentiating state, and enhances IL-8, IL-6 and G-CSF secretion during the first 12 h compared to non-treated cells. LPA-treated CD34⁺ cells delivered in fibrin gels have enhanced survival and improved cardiac fractional shortening at 2 weeks on rat infarcted hearts as compared to hearts treated with placebo. We have developed a new platform to enhance the survival of CD34⁺ cells using a natural and cost-effective ligand and demonstrated its utility in the preservation of the functionality of the heart after infarction.

Telmisartan prevention of LPS-induced microglia activation involves M2 microglia polarization via CaMKKβ-dependent AMPK activation

Brain inflammation plays an important role in the pathophysiology of many psychiatric and neurological diseases. During brain inflammation, microglia cells are activated, producing neurotoxic molecules and neurotrophic factors depending on their pro-inflammatory M1 and anti-inflammatory M2 phenotypes. It has been demonstrated that Angiotensin II type 1 receptor blockers (ARBs) ameliorate brain inflammation and reduce M1 microglia activation. The ARB telmisartan suppresses glutamate-induced upregulation of inflammatory genes in cultured primary neurons. We wished to clarify whether telmisartan, in addition, prevents microglia activation through polarization to an anti-inflammatory M2 phenotype. We found that telmisartan promoted M2 polarization and reduced M1 polarization in LPS-stimulated BV2 and primary microglia cells, effects partially dependent on PPARγ activation. The promoting effects of telmisartan on M2 polarization, were attenuated by an AMP-activated protein kinase (AMPK) inhibitor or AMPK knockdown, indicating that AMPK activation participates on telmisartan effects. Moreover, in LPS-stimulated BV2 cells, telmisartan enhancement of M2 gene expression was prevented by the inhibitor STO-609 and siRNA of calmodulin-dependent protein kinase kinase β (CaMKKβ), an upstream kinase of AMPK. Furthermore, telmisartan enhanced brain AMPK activation and M2 gene expression in a mouse model of LPS-induced neuroinflammation. In addition, telmisartan reduced the LPS-induced sickness behavior in this in vivo model, and this effect was prevented by prior administration of an AMPK inhibitor. Our results indicate that telmisartan can be considered as a novel AMPK activator, suppressing microglia activation by promoting M2 polarization. Telmisartan may provide a novel, safe therapeutic approach to treat brain disorders associated with enhanced inflammation.

Combined Salvianolic Acid B and Ginsenoside Rg1 Exerts Cardioprotection against Ischemia/Reperfusion Injury in Rats

Lack of pharmacological strategies in clinics restricts the patient prognosis with myocardial ischemia/reperfusion (I/R) injury. The aim of this study was to evaluate the cardioprotection of combined salvianolic acid B (SalB) and ginsenoside Rg1 (Rg1) against myocardial I/R injury and further investigate the underlying mechanism. I/R injury was induced by coronary artery ligation for Wistar male rats and hypoxia/reoxygenation injury was induced on H9c2 cells. Firstly, the best ratio between SalB and Rg1was set as 2:5 based on their effects on heart function detected by hemodynamic measurement. Then SalB-Rg1 (2:5) was found to maintain mitochondrial membrane potential and resist apoptosis and necrosis in H9c2 cell with hypoxia/reoxygenation injury. Companying with same dose of SalB or Rg1 only, SalB-Rg1 showed more significant effects on down-regulation of myocardial infarct size, maintenance of myocardium structure, improvement on cardiac function, decrease of cytokine secretion including TNF-α, IL-1β, RANTES and sVCAM-1. Finally, the SalB-Rg1 improved the viability of cardiac myocytes other than cardiac fibroblasts in rats with I/R injury using flow cytometry. Our results revealed that SalB-Rg1 was a promising strategy to prevent myocardial I/R injury.

Thymoquinone Protects against Myocardial Ischemic Injury by Mitigating Oxidative Stress and Inflammation

The present study was aimed at investigating the cardioprotective activity of thymoquinone (TMQ), an active principle of the herb, Nigella sativa, which is used for the management of various diseases. The present study examined the cardioprotective effect of TMQ in isoproterenol- (ISP-) induced myocardial infarction in rats. Myocardial infarction was induced by two subcutaneous injections of ISP (85 mg/kg) at an interval of 24 hr. TMQ (20 mg/kg) was administered orally for 21 days. ISP-treated rats showed depletion of antioxidants and marker enzymes from myocardium along with lipid peroxidation and enhanced levels of proinflammatory cytokines. ISP also induced histopathological alterations in myocardium. Treatment with TMQ prevented the depletion of endogenous antioxidants and myocyte injury marker enzymes and inhibited lipid peroxidation as well as reducing the levels of proinflammatory cytokines. TMQ pretreatment also reduced myonecrosis, edema, and infiltration of inflammatory cells and showed preservation of cardiomyocytes histoarchitecture. The present study results demonstrate that TMQ exerts cardioprotective effect by mitigating oxidative stress, augmenting endogenous antioxidants, and maintaining structural integrity. The results of the present study indicate that TMQ may serve as an excellent agent alone or as adjuvant to prevent the onset and progression of myocardial injury.

C1q/tumor necrosis factor-related protein-6 attenuates post-infarct cardiac fibrosis by targeting RhoA/MRTF-A pathway and inhibiting myofibroblast differentiation

C1q/tumor necrosis factor-related protein-6 (CTRP6) is a newly identified adiponectin paralog with modulation effects on metabolism and inflammation. However, the cardiovascular function of CTRP6 remains unknown. This study aimed to determine its role in cardiac fibrosis and explore the possible mechanism. Myocardial infarction (MI) was induced by left anterior descending coronary artery ligation in rats. CTRP6 was mainly expressed in the cytoplasm of adult rat cardiomyocytes and significantly decreased in the border and infarct zones post-MI. Adenovirus-mediated CTRP6 delivery improved cardiac function, attenuated cardiac hypertrophy, alleviated cardiac fibrosis, and inhibited myofibroblast differentiation as well as the expression of collagen I, collagen III, and connective tissue growth factor post-MI. In cultured adult rat cardiac fibroblasts (CFs), exogenous or cardiomyocyte-secreted CTRP6 inhibited, whereas knockdown of CTRP6 facilitated transforming growth factor-β1 (TGF-β1)-induced expression of α-smooth muscle actin, smooth muscle 22α, and profibrotic molecules. CTRP6 had no effect on CFs proliferation but attenuated CFs migration induced by TGF-β1. CTRP6 increased the phosphorylation of AMP-activated protein kinase (AMPK) and Akt in CFs and post-MI hearts. Pretreatment with adenine 9-β-D-arabinofuranoside (AraA), an AMPK inhibitor, or LY294002, a phosphatidylinositol-3-kinase (PI3 K) inhibitor, abolished the protective effect of CTRP6 on TGF-β1-induced profibrotic response. Furthermore, CTRP6 had no effect on TGF-β1-induced Smad3 phosphorylation and nuclear translocation, whereas significantly decreased TGF-β1-induced RhoA activation and myocardin-related transcription factor-A (MRTF-A) nuclear translocation, and these effects were blocked by AMPK or Akt inhibition. In conclusion, CTRP6 attenuates cardiac fibrosis via inhibiting myofibroblast differentiation. AMPK and Akt activation are responsible for the CTRP6-mediated anti-fibrotic effect by targeting RhoA/MRTF-A pathway.

Metabolic shifts during aging and pathology

The heart is a very special organ in the body and has a high requirement for metabolism due to its constant workload. As a consequence, to provide a consistent and sufficient energy a high steady-state demand of metabolism is required by the heart. When delicately balanced mechanisms are changed by physiological or pathophysiological conditions, the whole system's homeostasis will be altered to a new balance, which contributes to the pathologic process. So it is no wonder that almost every heart disease is related to metabolic shift. Furthermore, aging is also found to be related to the reduction in mitochondrial function, insulin resistance, and dysregulated intracellular lipid metabolism. Adenosine monophosphate-activated protein kinase (AMPK) functions as an energy sensor to detect intracellular ATP/AMP ratio and plays a pivotal role in intracellular adaptation to energy stress. During different pathology (like myocardial ischemia and hypertension), the activation of cardiac AMPK appears to be essential for repairing cardiomyocyte's function by accelerating ATP generation, attenuating ATP depletion, and protecting the myocardium against cardiac dysfunction and apoptosis. In this overview, we will talk about the normal heart's metabolism, how metabolic shifts during aging and different pathologies, and how AMPK regulates metabolic changes during these conditions.