Treatment with dimethylthiourea prevents left ventricular remodeling and failure after experimental myocardial infarction in mice: role of oxidative stress

Acylated ghrelin protection inhibits apoptosis in the remote myocardium post-myocardial infarction by inhibiting calcineurin and activating ARC

This study investigated if acylated ghrelin (AG) could inhibit myocardial infarction (MI)-induced apoptosis in the left ventricles (LV) of male rats and tested if this protection involves modulating ARC anti-apoptotic protein. Rats (n = 12/group) were assigned as a sham-operated, a sham + AG (100 µg/kg, 2x/d, S.C.), MI, and MI + AG. With no antioxidant activity or expression of FAS, AG inhibited caspase-3, 8, and 9 and decreased cytosolic/mitochondrial levels of cytochrome-c, Bax, Bad, and Bad-BCL-2 complex in the LVs of the sham-operated and MI-treated rats. Concomitantly, AG preserved the mitochondria structure, decreased mtPTP, and enhanced state-3 respiration in the LVs of both treated groups. These effects were associated with increased mitochondrial levels of ARC and a reduction in the activity of calcineurin. Overall, AG suppresses MI-induced ventricular apoptosis by inhibition of calcineurin, activation of ARC, and preserving mitochondria integrity.

Microbiota-derived short-chain fatty acids: Implications for cardiovascular and metabolic disease

Cardiovascular diseases (CVDs) have been on the rise around the globe in the past few decades despite the existing guidelines for prevention and treatment. Short-chain fatty acids (SCFAs) are the main metabolites of certain colonic anaerobic bacterial fermentation in the gastrointestinal tract and have been found to be the key metabolites in the host of CVDs. Accumulating evidence suggest that the end-products of SCFAs (including acetate, propionate, and butyrate) interact with CVDs through maintaining intestinal integrity, anti-inflammation, modulating glucolipid metabolism, blood pressure, and activating gut-brain axis. Recent advances suggest a promising way to prevent and treat CVDs by controlling SCFAs. Hence, this review tends to summarize the functional roles carried out by SCFAs that are reported in CVDs studies. This review also highlights several novel therapeutic interventions for SCFAs to prevent and treat CVDs.

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.

An Overview of the Molecular Mechanisms Associated with Myocardial Ischemic Injury: State of the Art and Translational Perspectives

Cardiovascular disease is the leading cause of death in western countries. Among cardiovascular diseases, myocardial infarction represents a life-threatening condition predisposing to the development of heart failure. In recent decades, much effort has been invested in studying the molecular mechanisms underlying the development and progression of ischemia/reperfusion (I/R) injury and post-ischemic cardiac remodeling. These mechanisms include metabolic alterations, ROS overproduction, inflammation, autophagy deregulation and mitochondrial dysfunction. This review article discusses the most recent evidence regarding the molecular basis of myocardial ischemic injury and the new potential therapeutic interventions for boosting cardioprotection and attenuating cardiac remodeling.

New Insights Into the Role of Mitochondria Quality Control in Ischemic Heart Disease

IHD is a significant cause of mortality and morbidity worldwide. In the acute phase, it's demonstrated as myocardial infarction and ischemia-reperfusion injury, while in the chronic stage, the ischemic heart is mainly characterised by adverse myocardial remodelling. Although interventions such as thrombolysis and percutaneous coronary intervention could reduce the death risk of these patients, the underlying cellular and molecular mechanisms need more exploration. Mitochondria are crucial to maintain the physiological function of the heart. During IHD, mitochondrial dysfunction results in the pathogenesis of ischemic heart disease. Ischemia drives mitochondrial damage not only due to energy deprivation, but also to other aspects such as mitochondrial dynamics, mitochondria-related inflammation, etc. Given the critical roles of mitochondrial quality control in the pathological process of ischemic heart disease, in this review, we will summarise the efforts in targeting mitochondria (such as mitophagy, mtROS, and mitochondria-related inflammation) on IHD. In addition, we will briefly revisit the emerging therapeutic targets in this field.

Huoxin pill prevents acute myocardial ischaemia injury via inhibition of Wnt/β-catenin signaling

Myocardial infarction (MI) is one of the leading causes of death worldwide, and due to the widespread and irreversible damage caused, new therapeutic treatments are urgently needed in order to limit the degree of ischaemic damage following MI. Aberrant activation of Wnt/β‐catenin signalling pathway often occurs during cardiovascular diseases including MI, which results in excess production of reactive oxygen species (ROS) and further promotes myocardial dysfunction. Huoxin pill (HXP) is a Traditional Chinese Medicine formula that has been widely used in the treatment of coronary heart disease and angina; however, its mechanisms remain unclear. Here, we performed mouse models of MI and examined the effects and mechanisms of HXP in protecting against MI‐induced ischaemic damage. Our study showed that administration with HXP robustly protected against MI‐induced cardiac injuries, decreased infarct size and improved cardiac function. Moreover, HXP attenuated ischaemia‐induced DNA damage occurrence in vivo and H₂O₂‐induced DNA damage occurrence in vitro, via potent inhibition of adverse Wnt/β‑catenin signalling activation. Our study thus elucidated the role and mechanism of HXP in protecting against MI and oxidative stress‐induced injuries and suggests new therapeutic strategies in ischaemic heart disease via inhibition of Wnt/β‐catenin signalling pathway.

Ghrelin ameliorates cardiac fibrosis after myocardial infarction by regulating the Nrf2/NADPH/ROS pathway

To evaluate the role of ghrelin in cardiac fibrosis after myocardial infarction (MI) and to investigate the underlying mechanisms of ghrelin-regulated Nrf2/NADPH/ROS pathway-mediated cardioprotection, the profile of Nrf2, fibrosis markers, and oxidative stress markers were characterized in a rat model of MI and Angiotensin II (Ang II)-stimulated cardiac fibroblasts (CFs). The effects of ghrelin on cardiac function, fibrosis and oxidative stress were investigated after MI in vivo. The role of ghrelin in CF migration and proliferation was evaluated in Ang II-stimulated CFs in vitro. Inhibition of ghrelin receptors using the antagonist, d-Lys3-GHRP-6, in addition to ghrelin was employed in MI and CFs to investigate the direct effect of ghrelin on cardiac fibrosis. Loss function of Nrf2 in CFs was performed to investigate the effect of ghrelin-regulated Nrf2 on oxidative stress and cardiac fibrosis. Ghrelin improved the post-MI cardiac function and reduced cardiac fibrosis. This phenotype is associated with the upregulation of Nrf2 and downregulation of fibrotic proteins, NADPH oxidase and ROS production. In line with in vivo findings, ghrelin attenuated Ang II-stimulated CF migration, proliferation, and oxidative stress in vitro. Inhibition of the ghrelin receptor or knockdown of Nrf2 abolished the beneficial effects of ghrelin on MI or Ang II-stimulated cardiac fibroblasts. In conclusion, ghrelin ameliorates post-MI and Ang II-induced cardiac fibrosis by activating Nrf2, which in turn inhibits the NADPH/ROS pathway.

Protective Effects of Estrogen on Cardiovascular Disease Mediated by Oxidative Stress

Perimenopause is an important stage of female senescence. Epidemiological investigation has shown that the incidence of cardiovascular disease in premenopausal women is lower than that in men, and the incidence of cardiovascular disease in postmenopausal women is significantly higher than that in men. This phenomenon reveals that estrogen has a definite protective effect on the cardiovascular system. In the cardiovascular system, oxidative stress is considered important in the pathogenesis of atherosclerosis, myocardial dysfunction, cardiac hypertrophy, heart failure, and myocardial ischemia. From the perspective of oxidative stress, estrogen plays a regulatory role in the cardiovascular system through the estrogen receptor, providing strategies for the treatment of menopausal women with cardiovascular diseases.

Modulations of Cardiac Functions and Pathogenesis by Reactive Oxygen Species and Natural Antioxidants

Homeostasis in the level of reactive oxygen species (ROS) in cardiac myocytes plays a critical role in regulating their physiological functions. Disturbance of balance between generation and removal of ROS is a major cause of cardiac myocyte remodeling, dysfunction, and failure. Cardiac myocytes possess several ROS-producing pathways, such as mitochondrial electron transport chain, NADPH oxidases, and nitric oxide synthases, and have endogenous antioxidation mechanisms. Cardiac Ca²⁺-signaling toolkit proteins, as well as mitochondrial functions, are largely modulated by ROS under physiological and pathological conditions, thereby producing alterations in contraction, membrane conductivity, cell metabolism and cell growth and death. Mechanical stresses under hypertension, post-myocardial infarction, heart failure, and valve diseases are the main causes for stress-induced cardiac remodeling and functional failure, which are associated with ROS-induced pathogenesis. Experimental evidence demonstrates that many cardioprotective natural antioxidants, enriched in foods or herbs, exert beneficial effects on cardiac functions (Ca²⁺ signal, contractility and rhythm), myocytes remodeling, inflammation and death in pathological hearts. The review may provide knowledge and insight into the modulation of cardiac pathogenesis by ROS and natural antioxidants.

Cardiac-specific loss of mitoNEET expression is linked with age-related heart failure

Heart failure (HF) occurs frequently among older individuals, and dysfunction of cardiac mitochondria is often observed. We here show the cardiac-specific downregulation of a certain mitochondrial component during the chronological aging of mice, which is detrimental to the heart. MitoNEET is a mitochondrial outer membrane protein, encoded by CDGSH iron sulfur domain 1 (CISD1). Expression of mitoNEET was specifically downregulated in the heart and kidney of chronologically aged mice. Mice with a constitutive cardiac-specific deletion of CISD1 on the C57BL/6J background showed cardiac dysfunction only after 12 months of age and developed HF after 16 months; whereas irregular morphology and higher levels of reactive oxygen species in their cardiac mitochondria were observed at earlier time points. Our results suggest a possible mechanism by which cardiac mitochondria may gradually lose their integrity during natural aging, and shed light on an uncharted molecular basis closely related to age-associated HF.

Cardiac adaptation and cardioprotection against arrhythmias and ischemia-reperfusion injury in mammalian hibernators

Hibernation allows animals to enter an energy conserving state to survive severe drops in external temperatures and a shortage of food. It has been observed that the hearts of mammalian hibernators exhibit intrinsic protection against ischemia-reperfusion (I/R) injury and cardiac arrhythmias in the winter whether they are hibernating or not. However, the molecular and ionic mechanisms for cardioprotection in mammalian hibernators remain elusive. Recent studies in woodchucks (Marmota monax) have suggested that cardiac adaptation occurs at different levels and mediates an intrinsic cardioprotection prior to/in the winter. The molecular/cellular remodeling in the winter (with or without hibernation) includes (1) an upregulation of transcriptional factor, anti-apoptotic factor, nitric oxide synthase, protein kinase C-ε, and phosphatidylinositol-4,5-bisphosphate 3-kinase; (2) an upregulation of antioxidant enzymes (e.g. superoxide dismutase and catalase); (3) a reduction in the oxidation level of Ca²⁺/calmodulin-dependent protein kinase II (CaMKII); and (4) alterations in the expression and activity of multiple ion channels/transporters. Therefore, the cardioprotection against I/R injury in the winter is most likely mediated by enhancement in signaling pathways that are shared by preconditioning, reduced cell apoptosis, and increased detoxification of reactive oxygen species (ROS). The resistance to cardiac arrhythmias and sudden cardiac death in the winter is closely associated with an upregulation of the antioxidant catalase and a downregulation of CaMKII activation. This remodeling of the heart is associated with a reduction in the incidence of afterdepolarizations and triggered activities. In this short review article, we will discuss the seasonal changes in gene and protein expression profiles as well as alterations in the function of key proteins that are associated with the occurrence of cardioprotection against myocardial damage from ischemic events and fatal arrhythmias in a mammalian hibernator. Understanding the intrinsic cardiac adaptive mechanisms that confer cardioprotection in hibernators may offer new strategies to protect non-hibernating animals, especially humans, from I/R injury and ischemia-induced fatal cardiac arrhythmias.

Natural Drugs as a Treatment Strategy for Cardiovascular Disease through the Regulation of Oxidative Stress

Oxidative stress (OS) refers to the physiological imbalance between oxidative and antioxidative processes leading to increased oxidation, which then results in the inflammatory infiltration of neutrophils, increased protease secretion, and the production of a large number of oxidative intermediates. Oxidative stress is considered an important factor in the pathogenesis of cardiovascular disease (CVD). At present, active components of Chinese herbal medicines (CHMs) have been widely used for the treatment of CVD, including coronary heart disease and hypertension. Since the discovery of artemisinin for the treatment of malaria by Nobel laureate Youyou Tu, the therapeutic effects of active components of CHM on various diseases have been widely investigated by the medical community. It has been found that various active CHM components can regulate oxidative stress and the circulatory system, including ginsenoside, astragaloside, and resveratrol. This paper reviews advances in the use of active CHM components that modulate oxidative stress, suggesting potential drugs for the treatment of various CVDs.

Inhibition of urea transporter ameliorates uremic cardiomyopathy in chronic kidney disease

Uremic cardiomyopathy, characterized by hypertension, cardiac hypertrophy, and fibrosis, is a complication of chronic kidney disease (CKD). Urea transporter (UT) inhibition increases the excretion of water and urea, but the effect on uremic cardiomyopathy has not been studied. We tested UT inhibition by dimethylthiourea (DMTU) in 5/6 nephrectomy mice. This treatment suppressed CKD-induced hypertension and cardiac hypertrophy. In CKD mice, cardiac fibrosis was associated with upregulation of UT and vimentin abundance. Inhibition of UT suppressed vimentin amount. Left ventricular mass index in DMTU-treated CKD was less compared with non-treated CKD mice as measured by echocardiography. Nephrectomy was performed in UT-A1/A3 knockout (UT-KO) to further confirm our finding. UT-A1/A3 deletion attenuates the CKD-induced increase in cardiac fibrosis and hypertension. The amount of α-smooth muscle actin and tgf-β were significantly less in UT-KO with CKD than WT/CKD mice. To study the possibility that UT inhibition could benefit heart, we measured the mRNA of renin and angiotensin-converting enzyme (ACE), and found both were sharply increased in CKD heart; DMTU treatment and UT-KO significantly abolished these increases. Conclusion: Inhibition of UT reduced hypertension, cardiac fibrosis, and improved heart function. These changes are accompanied by inhibition of renin and ACE.

Higher Epoxyeicosatrienoic Acids in Cardiomyocytes-Specific CYP2J2 Transgenic Mice Are Associated with Improved Myocardial Remodeling

Elevated cis-epoxyeicosatrienoic acids (EETs) are known to be cardioprotective during ischemia-reperfusion injury in cardiomyocyte-specific overexpressing cytochrome P450 2J2 (CYP2J2) transgenic (Tr) mice. Using the same Tr mice, we measured changes in cardiac and erythrocyte membranes EETs following myocardial infarction (MI) to determine if they can serve as reporters for cardiac events. Cardiac function was also assessed in Tr vs. wild-type (WT) mice in correlation with EET changes two weeks following MI. Tr mice (N = 25, 16 female, nine male) had significantly higher cardiac cis- and trans-EETs compared to their WT counterparts (N = 25, 18 female, seven male). Total cardiac cis-EETs in Tr mice were positively correlated with total cis-EETs in erythrocyte membrane, but there was no correlation with trans-EETs or in WT mice. Following MI, cis- and trans-EETs were elevated in the erythrocyte membrane and cardiac tissue in Tr mice, accounting for the improved cardiac outcomes observed. Tr mice showed significantly better myocardial remodeling following MI, evidenced by higher % fractional shortening, smaller infarct size, lower reactive oxygen species (ROS) formation, reduced fibrosis and apoptosis, and lower pulmonary edema. A positive correlation between total cardiac cis-EETs and total erythrocyte membrane cis-EETs in a Tr mouse model suggests that erythrocyte cis-EETs may be used as predictive markers for cardiac events. All cis-EET regioisomers displayed similar trends following acute MI; however, the magnitude of change for each regioisomer was markedly different, warranting measurement of each individually.

Therapeutic Efficacy of Alpha-Lipoic Acid against Acute Myocardial Infarction and Chronic Left Ventricular Remodeling in Mice

Background

We hypothesized that daily administration of a potent antioxidant (α-lipoic acid: ALA) would protect the heart against both acute myocardial infarction (AMI) and left ventricular remodeling (LVR) post-AMI.

Methods and Results

Two separate studies were conducted. In the AMI study, C57Bl/6 mice were fed ALA daily for 7 d prior to a 45-minute occlusion of the left coronary artery (LCA). Mean infarct size in control mice (fed water) was 60 ± 2%. Mean infarct size in ALA-treated mice was 42 ± 3% in the 15 mg/kg·d group and 39 ± 3% in the 75 mg/kg·d group (both P < 0.05 vs. control). In the LVR study, AMI increased LV end-systolic volume (LVESV) and reduced LV ejection fraction (LVEF) to a similar extent in both groups when assessed by cardiac MRI 1 day after a 2-hour LCA occlusion. Treatment with ALA (75 mg/kg·d) or H₂O was initiated 1 day post-AMI and continued until study's end. Both LVESV and LVEF in ALA-treated mice were significantly improved over control when assessed 28 or 56 days post-AMI. Furthermore, the survival rate in ALA-treated mice was 63% better than in control mice by 56 days post-AMI.

Conclusions

Daily oral ingestion of ALA not only protects mice against AMI but also attenuates LVR and preserves contractile function in the months that follow.

Angiotensin-converting-enzyme inhibitor prevents skeletal muscle fibrosis in myocardial infarction mice

BACKGROUND

Transforming growth factor beta (TGF-β)-Smad2/3 is the major signaling pathway of fibrosis, which is characterized by the excessive production and accumulation of extracellular matrix (ECM) components, including collagen. Although the ECM is an essential component of skeletal muscle, fibrosis may be harmful to muscle function. On the other hand, our previous studies have shown that levels of angiotensin II, which acts upstream of TGF-β-Smad2/3 signaling, is increased in mice with myocardial infarction (MI). In this study, we found higher skeletal muscle fibrosis in MI mice compared with control mice, and we investigated the mechanisms involved therein. Moreover, we administered an inhibitor based on the above mechanism and investigated its preventive effects on skeletal muscle fibrosis.

METHODS

Male C57BL/6 J mice with MI were created, and sham-operated mice were used as controls. The time course of skeletal muscle fibrosis post-MI was analyzed by picrosirius-red staining (days 1, 3, 7, and 14). Mice were then divided into 3 groups: sham + vehicle (Sham + Veh), MI + Veh, and MI + lisinopril (an angiotensin-converting enzyme [ACE] inhibitor, 20 mg/kg body weight/day in drinking water; MI + Lis). Lis or Veh was administered from immediately after the surgery to 14 days postsurgery.

RESULTS

Skeletal muscle fibrosis was significantly increased in MI mice compared with sham mice from 3 to 14 days postsurgery. Although mortality was lower in the MI + Lis mice than the MI + Veh mice, there was no difference in cardiac function between the 2 groups at 14 days. Skeletal muscle fibrosis and hydroxyproline (a key marker of collagen content) were significantly increased in MI + Veh mice compared with the Sham + Veh mice. Consistent with these results, protein expression of TGF-β and phosphorylated Smad2/3 in the skeletal muscle during the early time points after surgery (days 1-7 postsurgery) and blood angiotensin II at 14 days postsurgery was increased in MI mice compared with sham mice. These impairments were improved in MI + Lis mice, without any effects on spontaneous physical activity, muscle strength, muscle weight, and blood pressure.

CONCLUSIONS

ACE inhibitor administration prevents increased skeletal muscle fibrosis during the early phase after MI. Our findings indicate a new therapeutic target for ameliorating skeletal muscle abnormalities in heart diseases.

Increased the risk of heart failure and comorbidities in patients with gout treatment: a population-based cohort study

Background

To investigate the association between gout treatment and heart failure (HF).

Methods

Patients with gout between 2000 and 2010 constituted the gout cohort. The main outcome was a new diagnosis of HF. Multivariable Cox proportional hazard regression models were used to measure the effect of gout on the risk of developing HF. The Kaplan-Meier method was used to estimate the cumulative HF incidence curve for the gout and nongout cohorts.

Results

The cohort study included 50,166 patients with gout. The incidence of HF was 1.96 times higher in the gout cohort than the non-gout cohort (7.11 vs. 3.63 per 10,000 person-years). The adjusted HR of developing HF was a 1.06-fold increase (95% CI: 1.06–1.07) with age and a 1.08-fold increase for women compared with men (95% CI: 1.02–1.14). HF incidence was higher in patients with receiving any two or more types of anti-gout drug treatment.

Conclusions

Our study revealed that gout could increase the risk of HF. Gout treatment in Taiwan cannot improve HF and actually increase the risk for HF after combination therapy for gout. The public health burden of gout should be resolved in the future.

Mitochondrial ROS in myocardial ischemia reperfusion and remodeling

Despite major progress in interventional and medical treatments, myocardial infarction (MI) and subsequent development of heart failure (HF) are still associated with high mortality. Both during ischemia reperfusion (IR) in the acute setting of MI, as well as in the chronic remodeling process following MI, oxidative stress substantially contributes to cardiac damage. Reactive oxygen species (ROS) generated within mitochondria are particular drivers of mechanisms contributing to IR injury, including induction of mitochondrial permeability transition or oxidative damage of intramitochondrial structures and molecules. But even beyond the acute setting, mechanisms like inflammatory signaling, extracellular remodeling, or pro-apoptotic signaling that contribute to post-infarction remodeling are regulated by mitochondrial ROS. In the current review, we discuss both sources and consequences of mitochondrial ROS during IR and in the chronic setting following MI, thereby emphasizing the potential therapeutic value of attenuating mitochondrial ROS to improve outcome and prognosis for patients suffering MI.

Association of tramadol with risk of myocardial infarction among patients with osteoarthritis

OBJECTIVE

Tramadol has been widely used among patients with osteoarthritis (OA); however, there is paucity of information on its cardiovascular risk. We aimed to examine the association of tramadol with risk of myocardial infarction (MI) among patients with OA.

DESIGN

Among OA patients aged 50-90 years without history of MI, cancer, or opioid use disorder in The Health Improvement Network database in the United Kingdom (2000-2016), three sequential propensity-score matched cohort studies were assembled, i.e., (1) patients who initiated tramadol or naproxen (negative comparator); (2) patients who initiated tramadol or diclofenac (positive comparator); and (3) patients who initiated tramadol or codeine (a commonly used weak opioid). The outcome was incident MI over six-months.

RESULTS

Among tramadol and naproxen initiators (n = 33,024 in each cohort), 77 (4.8/1000 person-years) and 46 (2.8/1000 person-years) incident MI occurred, respectively. The rate difference (RD) and hazard ratios (HR) for incident MI with tramadol initiation were 1.9 (95% confidence interval [CI] 0.6 to 2.3)/1000 person-years and 1.68 (95% CI 1.16 to 2.41) relative to naproxen initiation, respectively. Among tramadol and diclofenac initiators (n = 18,662 in each cohort), 58 (6.4/1000 person-years) and 47 (5.1/1000 person-years) incident MIs occurred, respectively. The corresponding RD and HR for incident MI were 1.2 (95%CI -2.1 to 14.1)/1000 person-years and 1.24 (95%CI 0.84 to 1.82), respectively. Among tramadol and codeine initiators (n = 42,722 in each cohort), 127 (6.1/1000 person-years) and 103 (5.0/1000 person-years) incident MI occurred, respectively, and the corresponding RD and HR were 1.1 (95%CI:-0.3 to 2.5)/1000 person-years and 1.23 (95%CI:0.95 to 1.60), respectively.

CONCLUSIONS

In this population-based cohort of patients with OA, the six-month risk of MI among initiators of tramadol was higher than that of naproxen, but comparable to, if not lower than, those of diclofenac or codeine.

Linoleic acid improves assembly of the CII subunit and CIII2/CIV complex of the mitochondrial oxidative phosphorylation system in heart failure

Background

Linoleic acid is the major fatty acid moiety of cardiolipin, which is central to the assembly of components involved in mitochondrial oxidative phosphorylation (OXPHOS). Although linoleic acid is an essential nutrient, its excess intake is harmful to health. On the other hand, linoleic acid has been shown to prevent the reduction in cardiolipin content and to improve mitochondrial function in aged rats with spontaneous hypertensive heart failure (HF). In this study, we found that lower dietary intake of linoleic acid in HF patients statistically correlates with greater severity of HF, and we investigated the mechanisms therein involved.

Methods

HF patients, who were classified as New York Heart Association (NYHA) functional class I (n = 45), II (n = 93), and III (n = 15), were analyzed regarding their dietary intakes of different fatty acids during the one month prior to the study. Then, using a mouse model of HF, we confirmed reduced cardiolipin levels in their cardiac myocytes, and then analyzed the mechanisms by which dietary supplementation of linoleic acid improves cardiac malfunction of mitochondria.

Results

The dietary intake of linoleic acid was significantly lower in NYHA III patients, as compared to NYHA II patients. In HF model mice, both CI-based and CII-based OXPHOS activities were affected together with reduced cardiolipin levels. Silencing of CRLS1, which encodes cardiolipin synthetase, in cultured cardiomyocytes phenocopied these events. Feeding HF mice with linoleic acid improved both CI-based and CII-based respiration as well as left ventricular function, together with an increase in cardiolipin levels. However, although assembly of the respirasome (i.e., CI/CIII₂/CIV complex), as well as assembly of CII subunits and the CIII₂/CIV complex statistically correlated with cardiolipin levels in cultured cardiomyocytes, respirasome assembly was not notably restored by dietary linoleic acid in HF mice. Therefore, although linoleic acid may significantly improve both CI-based and CII-based respiration of cardiomyocytes, respirasomes impaired by HF were not easily repaired by the dietary intake of linoleic acid.

Conclusions

Dietary supplement of linoleic acid is beneficial for improving cardiac malfunction in HF, but is unable to completely cure HF.

Oxidative Stress in Cardiovascular Diseases: Still a Therapeutic Target?

Cardiovascular diseases (CVD) are complex entities with heterogenous pathophysiologic mechanisms and increased oxidative stress has been viewed as one of the potential common etiologies. A fine balance between the presence of reactive oxygen species (ROS) and antioxidants is essential for the proper normal functioning of the cell. A basal concentration of ROS is indispensable for the manifestation of cellular functions, whereas excessive levels of ROS cause damage to cellular macromolecules such as DNA, lipids and proteins, eventually leading to necrosis and apoptotic cell death. CVD is the main cause of death worldwide with several conditions being affected by oxidative stress. Increased ROS lead to decreased nitric oxide availability and vasoconstriction, promoting arterial hypertension. ROS also negatively influence myocardial calcium handling, causing arrhythmia, and augment cardiac remodeling by inducing hypertrophic signaling and apoptosis. Finally, ROS have also been shown to promote atherosclerotic plaque formation. This review aims at giving an introduction into oxidative stress in CVD, with special focus on endothelial dysfunction, and then examining in detail the role of oxidative stress in the most prevalent of these diseases. Finally, potential nutraceuticals and diets that might be beneficial in diminishing the burden of oxidative stress in CVD are presented.

Increase of NADPH oxidase 3 in heart failure of hereditary cardiomyopathy

During the development of heart failure in humans and animal models, an increase in reactive oxygen species (ROS) levels was observed. However, there is no information whether this increase of ROS is associated with an increase in the density of specific isoforms of NADPH oxidases (NOXs) 1–5. The objective of this study was to verify whether the densities of NOXs 1–5 change during the development of heart failure. Using the well-known model of cardiomyopathic hamsters, the UM-X 7.1 line, a model that strongly resembles the pathology observed in humans from a morphological and functional point of view, our studies showed that, as in humans, NOXs 1–5 are present in both normal and UM-X7.1 hamster hearts. Even though the densities of NOXs 2 and 5 were unchanged, the levels of both NOXs 1 and 4 significantly decreased in UM-X7.1 hamster hearts during heart failure. These changes were accompanied with a significant increase in NOX3 level. These results suggest that, during heart failure, NOX3 plays a vital role in compensating the decrease of NOXs 1 and 4. This increase in NOX3 may also be responsible, at least in part, for the reported increase in ROS levels in heart failure.

Guidelines for evaluating myocardial cell death

Cell death is a fundamental process in cardiac pathologies. Recent studies have revealed multiple forms of cell death, and several of them have been demonstrated to underlie adverse cardiac remodeling and heart failure. With the expansion in the area of myocardial cell death and increasing concerns over rigor and reproducibility, it is important and timely to set a guideline for the best practices of evaluating myocardial cell death. There are six major forms of regulated cell death observed in cardiac pathologies, namely apoptosis, necroptosis, mitochondrial-mediated necrosis, pyroptosis, ferroptosis, and autophagic cell death. In this article, we describe the best methods to identify, measure, and evaluate these modes of myocardial cell death. In addition, we discuss the limitations of currently practiced myocardial cell death mechanisms.

Role of Platelet Activation and Oxidative Stress in the Evolution of Myocardial Infarction

Myocardial infarction, commonly known as heart attack, evolves from the rupture of unstable atherosclerotic plaques to coronary thrombosis and myocardial ischemia–reperfusion injury. A body of evidence supports a close relationship between the alterations following an ischemia–reperfusion injury-induced oxidative stress and platelet activity. Through their critical role in thrombogenesis and inflammatory responses, platelets are fully (totally) implicated from atherothrombotic plaque formation to myocardial infarction onset and expansion. However, mere platelet aggregation prevention does not offer full protection, suggesting that other antiplatelet therapy mechanisms may also be involved. Thus, the present review discusses the integrative role of platelets, oxidative stress, and antiplatelet therapy in triggering myocardial infarction pathophysiology.

NADPH Oxidase 4 Regulates Inflammation in Ischemic Heart Failure: Role of Soluble Epoxide Hydrolase

Aims: Oxidative stress is implicated in cardiomyocyte cell death and cardiac remodeling in the failing heart. The role of NADPH oxidase 4 (NOX4) in cardiac adaptation to pressure overload is controversial, but its function in myocardial ischemic stress has not been thoroughly elucidated. This study examined the function of NOX4 in the pathogenesis of ischemic heart failure, utilizing mouse models, cell culture, and human heart samples. Results:Nox4^-/- mice showed a protective phenotype in response to permanent left anterior descending coronary artery ligation with smaller infarction area, lower cardiomyocyte cross-sectional area, higher capillary density, and less cell death versus wild-type (WT) mice. Nox4^-/- mice had lower activity of soluble epoxide hydrolase (sEH), a potent regulator of inflammation. Nox4^-/- mice also showed a 50% reduction in the number of infiltrating CD68⁺ macrophages in the peri-infarct zone versus WT mice. Adenoviral overexpression of NOX4 in cardiomyoblast cells increased sEH expression and activity and CCL4 and CCL5 levels; inhibition of sEH activity in NOX4 overexpressing cells attenuated the cytokine levels. Human hearts with ischemic cardiomyopathy showed adverse cardiac remodeling, increased NOX4 and sEH protein expression and CCL4 and CCL5 levels compared with control nonfailing hearts. Innovation and Conclusion: These data from the Nox4^-/- mouse model and human heart tissues show for the first time that oxidative stress from increased NOX4 expression has a functional role in ischemic heart failure. One mechanism by which NOX4 contributes to ischemic heart failure is by increasing inflammatory cytokine production via enhanced sEH activity.

Innate immune response in the pathogenesis of heart failure in survivors of myocardial infarction

Among the different cardiovascular disease complications, atherosclerosis-induced myocardial infarction (MI) is the major contributor of heart failure (HF) and loss of life. This review presents short- and long-term features of post-MI in human hearts and animal models. It is known that the heart does not regenerate, and thus loss of cardiac cells after an MI event is permanent. In survivors of a heart attack, multiple neurohumoral adjustments as well as simultaneous remodeling in both infarcted and noninfarcted regions of the heart help sustain pump function post-MI. In the early phase, migration of inflammatory cells to the infarcted area helps repair and remove the cell debris, while apoptosis results in the elimination of damaged cardiomyocytes, and there is an increase in the antioxidant response to protect the survived myocardium against oxidative stress (OS) injury. However, in the late phase, it appears that there is a relative increase in OS and activation of the innate inflammatory response in cardiomyocytes without any obvious inflammatory cells. In this late stage in survivors of MI, a progressive slow activation of these processes leads to apoptosis, fibrosis, cardiac dysfunction, and HF. Thus, this second phase of an increase in OS, innate inflammatory response, and apoptosis results in wall thinning, dilatation, and consequently HF. It is important to note that this inflammatory response appears to be innate to cardiomyocytes. Blunting of this innate immune cardiomyocyte response may offer new hope for the management of HF.

Network pharmacology study reveals energy metabolism and apoptosis pathways-mediated cardioprotective effects of Shenqi Fuzheng

ETHNOPHARMACOLOGICAL RELEVANCE

Shenqi Fuzheng (SQ) is a renowned traditional Chinese medicine extracted from Radix Codonopsis and Radix Astragali. Although SQ is widely used to treat myocardial ischemia-reperfusion (I/R) injury, the molecular mechanisms supporting its clinical application remain elusive.

AIM OF THE STUDY

The purpose of current study was to understand its cardioprotective effects at the molecular level using network pharmacology approach.

MATERIALS AND METHOD

In an I/R injury animal model, the beneficial pharmacological activities of SQ were confirmed by decreased infarct range observed on drug treated rats versus control group. Additionally, several serum biochemical indicators were in concord with this observation. Subsequently, a microarray experiment was performed to reveal the influence on injured heart at the gene expression level by this TCM injection. We then proposed a network analysis algorithm NTRA to discover the key nodes based on both disease network structure and transcriptomics. Using NRI_ODN, a method developed by our group previously, the holistic changes on the gene network induced by for I/R injury and SQ treatment were evaluated.

RESULTS

Pathway enrichment analysis of highly ranked genes by NTRA showed that PPAR and apoptosis pathways were highly related to I/R injury. Finally, western blot results showed increased level of the PPARα and BAX protein in the heart after injection treatment which confirmed the hypothesis.

CONCLUSION

In conclusion, our results suggest that SQ injection exerts protective effect against myocardial ischemia-reperfusion injury through multiple pathways, including myocardial energy metabolism improvement, cell adhesion inhibition, inflammatory reaction perturbation, myocardial apoptosis reduction and ventricular remodeling avoidance.

Protein acetylation in skeletal muscle mitochondria is involved in impaired fatty acid oxidation and exercise intolerance in heart failure

BACKGROUND

Exercise intolerance is a common clinical feature and is linked to poor prognosis in patients with heart failure (HF). Skeletal muscle dysfunction, including impaired energy metabolism in the skeletal muscle, is suspected to play a central role in this intolerance, but the underlying mechanisms remain elusive. Lysine acetylation, a recently identified post-translational modification, has emerged as a major contributor to the derangement of mitochondrial metabolism. We thus investigated whether mitochondrial protein acetylation is associated with impaired skeletal muscle metabolism and lowered exercise capacity in both basic and clinical settings of HF.

METHODS

We first conducted a global metabolomic analysis to determine whether plasma acetyl-lysine is a determinant factor for peak oxygen uptake (peak VO₂ ) in HF patients. We then created a murine model of HF (n = 11) or sham-operated (n = 11) mice with or without limited exercise capacity by ligating a coronary artery, and we tested the gastrocnemius tissues by using mass spectrometry-based acetylomics. A causative relationship between acetylation and the activity of a metabolic enzyme was confirmed in in vitro studies.

RESULTS

The metabolomic analysis verified that acetyl-lysine was the most relevant metabolite that was negatively correlated with peak VO₂ (r = -0.81, P < 0.01). At 4 weeks post-myocardial infarction HF, a treadmill test showed lowered work (distance × body weight) and peak VO₂ in the HF mice compared with the sham-operated mice (11 ± 1 vs. 23 ± 1 J, P < 0.01; 143 ± 5 vs. 159 ± 3 mL/kg/min, P = 0.01; respectively). As noted, the protein acetylation of gastrocnemius mitochondria was 48% greater in the HF mice than the sham-operated mice (P = 0.047). Acetylproteomics identified the mitochondrial enzymes involved in fatty acid β-oxidation (FAO), the tricarboxylic acid cycle, and the electron transport chain as targets of acetylation. In parallel, the FAO enzyme (β-hydroxyacyl CoA dehydrogenase) activity and fatty acid-driven mitochondrial respiration were reduced in the HF mice. This alteration was associated with a decreased expression of mitochondrial deacetylase, Sirtuin 3, because silencing of Sirtuin 3 in cultured skeletal muscle cells resulted in increased mitochondrial acetylation and reduced β-hydroxyacyl CoA dehydrogenase activity.

CONCLUSIONS

Enhanced mitochondrial protein acetylation is associated with impaired FAO in skeletal muscle and reduced exercise capacity in HF. Our results indicate that lysine acetylation is a crucial mechanism underlying deranged skeletal muscle metabolism, suggesting that its modulation is a potential approach for exercise intolerance in HF.

Antioxidant defense and protection against cardiac arrhythmias: lessons from a mammalian hibernator (the woodchuck)

Hibernating animals show resistance to hypothermia-induced cardiac arrhythmias. However, it is not clear whether and how mammalian hibernators are resistant to ischemia-induced arrhythmias. The goal of this investigation was to determine the susceptibility of woodchucks ( Marmota monax) to arrhythmias and their mechanisms after coronary artery occlusion at the same room temperature in both winter, the time for hibernation, and summer, when they do not hibernate. By monitoring telemetric electrocardiograms, we found significantly higher arrhythmia scores, calculated as the severity of arrhythmias, with incidence of ventricular tachycardia, ventricular fibrillation, and thus sudden cardiac death (SCD) in woodchucks in summer than they had in winter. The level of catalase expression in woodchuck hearts was significantly higher, whereas the level of oxidized Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) was lower in winter than it was in summer. Ventricular myocytes isolated from woodchucks in winter were more resistant to H₂O₂-induced early afterdepolarizations (EADs) compared with myocytes isolated from woodchucks in summer. The EADs were eliminated by inhibiting CaMKII (with KN-93), l-type Ca current (with nifedipine), or late Na⁺ current (with ranolazine). In woodchucks, in the summer, the arrhythmia score was significantly reduced by overexpression of catalase ( via adenoviral vectors) or the inhibition of CaMKII (with KN-93) in the heart. This study suggests that the heart of the mammalian hibernator is more resistant to ischemia-induced arrhythmias and SCD in winter. Increased antioxidative capacity and reduced CaMKII activity may confer resistance in woodchuck hearts against EADs and arrhythmias during winter. The profound protection conferred by catalase overexpression or CaMKII inhibition in this novel natural animal model may provide insights into clinical directions for therapy of arrhythmias.-Zhao, Z., Kudej, R. K., Wen, H., Fefelova, N., Yan, L., Vatner, D. E., Vatner, S. F., Xie, L.-H. Antioxidant defense and protection against cardiac arrhythmias: lessons from a mammalian hibernator (the woodchuck).

Engineering Bioinspired Antioxidant Materials Promoting Cardiomyocyte Functionality and Maturation for Tissue Engineering Application

Oxidative stress plays an important role in various pathological conditions, such as wound healing, inflammation, myocardial infarction, and biocompatibility of the materials. Antioxidant polymers to attenuate oxidative stress is an emerging field of biomaterial research with a huge impact in the field of tissue engineering and regenerative medicine. We describe here the fabrication and evaluation of an elastomeric antioxidant polyurethane (PUAO) for tissue engineering applications. Uniaxial and cyclic tensile testing, thermal analysis, degradation, cytotoxicity and antioxidant analysis was carried out. An in vitro oxidative stress model demonstrated that PUAO reduced intracellular oxidative stress in H9C2 cardiomyocytes (p < 0.05) and attenuated reactive oxygen species (ROS) induced cell death (p < 0.001). Under simulated ischemic reperfusion, PUAO could rescue hypoxia induced cell death. Further as a proof of concept, neonatal rat cardiomyocytes cultured on PUAO film displayed synchronous beating with mature phenotype showing expression of cardiac specific α-actinin, troponin-T, and connexin-43 proteins. Intracellular calcium transients established the functionality of cultured cardiomyocytes on PUAO film. Our study demonstrated the potential of this biomaterial to be developed into tissue engineered scaffold to attenuate oxidative stress for treatment of diseased conditions with increased oxidative stress, such as cardiovascular diseases, chronic wound healing, and myocardial infarction.

Sesamin prevents apoptosis and inflammation after experimental myocardial infarction by JNK and NF-κB pathways

Myocardial infarction is a devastating event, especially when reperfusion is not performed. The inflammatory response has been associated with the pathogenesis of left ventricular remodeling after myocardial infarction. This study focused on the anti-apoptotic and anti-inflammatory effects of sesamin on ligation of the left anterior descending artery in an experimental mouse model and the potential mechanism underlying the activation of JNK and NF-κB pathways. Mice with MI induced by surgical left anterior descending coronary artery ligation were treated with sesamin by gavage for 1 week. Results showed that after treatment with sesamin, MI-induced cardiac damage was alleviated significantly, indicated by the histopathological examination. The myocardial apoptosis in the border zone was dramatically reduced by sesamin, resulting from the altered expression of apoptosis factors. Moreover, treatment with sesamin also mitigated the inflammatory response, decreased expression of cytokines and the inactivation of NF-κB (nuclear factor κB) signaling. Sesamin decreased the levels of p-JNK protein, which in turn inactivated pro-apoptotic signaling events by restoring the balance between mitochondrial pro-apoptotic Bcl-2 and Bax proteins. Thus, our study suggests that sesamin could alleviate MI-induced cardiac dysfunction through decrease of myocardial apoptosis and inflammatory response.

Galectin-3 mediates the pulmonary arterial hypertension-induced right ventricular remodeling through interacting with NADPH oxidase 4

Pulmonary arterial hypertension (PAH) is a progressive disorder that affects both pulmonary vasculature and the heart. The response of the right ventricle (RV) to the increased afterload is an important determinant of the PAH final outcome. Galectin-3 (Gal-3), a novel biomarker in left cardiac remodeling, takes part in multiple pathophysiological processes including the inflammation, fibrosis, immunity, and oxidative stress. The levels of Gal-3 are elevated in PAH patients, although the exact mechanisms underlie the PAH-induced right ventricular structural changes remain unclear. Our results showed that the serum Gal-3 and NADPH oxidase 4 (Nox4) levels were significantly elevated and correlated in 26 human PAH patients when compared with 14 age- and sex-matched healthy controls. In the monocrotaline-induced PAH rat models of right ventricular hypertrophy and fibrosis, the Gal-3 and Nox4 expressions were both significantly upregulated compared with the controls. Moreover, the Gal-3 positive areas were co-localized with the collagen III-specific staining and the Gal-3 and Nox4 were partly co-localized in the intercellular area. The exogenous Gal-3 recombinant protein stimulated the proliferation, differentiation, collagen deposition, and Nox4 expression of cardiac fibroblasts. These simulations were blocked by the Gal-3 knockdown. The profibrotic effects of transforming growth factor-β1 (TGF-β1) on the cardiac fibroblasts were partially mediated by the Gal-3. Subsequently, our results showed that Gal-3 mediated the TGF-β1-induced cardiac fibrotic process through interacting with the Nox4 and Nox4-derived oxidative stress. Therefore, Gal-3 plays an important role in the PAH-induced right ventricular remodeling through interacting with the Nox4 and Nox4-derived oxidative stress. Gal-3 may become a RV-specific diagnostic and therapeutic target for clinics.

Effect of paroxetine on left ventricular remodeling in an in vivo rat model of myocardial infarction

Left ventricular (LV) remodeling following a myocardial infarction (MI) involves formation of reactive oxygen species (ROS). Paroxetine, a selective serotonin reuptake inhibitor, has an antioxidant effect in the vascular wall. We investigated whether paroxetine reduces myocardial ROS formation and LV remodeling following a MI. In a total of 32 Wistar rats, MI was induced by a 30-min ligation of the left anterior descending artery followed by 7- or 28-day reperfusion. During the 28 days of reperfusion, LV remodeling was evaluated by magnetic resonance imaging (MRI) and echocardiography (n = 20). After 28 days of reperfusion, the susceptibility to ventricular tachycardia was evaluated prior to sacrifice and histological assessment of myocyte cross-sectional area, fibrosis, and presence of myofibroblasts. Myocardial ROS formation was measured with dihydroethidium after 7 days of reperfusion in separate groups (n = 12). Diastolic LV volume, evaluated by MRI (417 ± 60 vs. 511 ± 64 µL, p < 0.05), and echocardiography (515 ± 80 vs. 596 ± 83 µL, p < 0.05) as well as diastolic LV internal diameter evaluated with echocardiography (7.2 ± 0.6 vs. 8.1 ± 0.7 mm, p < 0.05) were lower in the paroxetine group than in controls. Furthermore, myocyte cross-sectional area was reduced in the paroxetine group compared with controls (277 ± 26 vs. 354 ± 23 mm³, p < 0.05) and ROS formation was reduced in the remote myocardium (0.415 ± 0.19 normalized to controls, p < 0.05). However, no differences in the presence of fibrosis or myofibroblasts were observed. Finally, paroxetine reduced the susceptibility to ventricular tachycardia (induced in 2/11 vs. 6/8 rats, p < 0.05). Paroxetine treatment following MI decreases LV remodeling and susceptibility to arrhythmias, probably by reducing ROS formation.

Effects of renal denervation on cardiac oxidative stress and local activity of the sympathetic nervous system and renin-angiotensin system in acute myocardial infracted dogs

Background

This study sought to evaluate the therapeutic effects of renal denervation (RDN) on acute myocardial infarction (MI) in canines and explore its possible mechanisms of action.

Methods

Eighteen healthy mongrel dogs were randomly assigned to either the control group, the MI group or the MI + RDN group. To assess cardiac function, left ventricular ejection fraction (LVEF), left ventricular end-diastolic dimension (LVEDD), left ventricular end-systolic dimension (LVESD) and fraction shortening (FS) were recorded. Additionally, haemodynamic parameters such as left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP) and heart rate (HR) were measured. Cardiac oxidative stress levels were evaluated based on the expression of p47^phox mRNA, malondialdehyde (MDA), anti-superoxide anion free radical (ASAFR) and activity of superoxide dismutase (SOD). To measure the local activity of the sympathetic nervous system (SNS) and renin-angiotensin system (RAS), the levels of tyrosine hydroxylase (TH), angiotensin II (AngII), angiotensin-converting enzyme 2 (ACE2), angiotensin (1–7) [Ang(1–7)] and Mas receptor (MasR) in myocardial tissues were recorded. The expression of TH in renal tissue and serum creatinine were used to assess the effectiveness of the RDN procedure and renal function, respectively.

Results

We found that MI deteriorated heart function and activated cardiac oxidative stress and the local neurohumoral system, while RDN partially reversed these changes. Compared with the control group, parameters including LVEDD, LVESD, LVEDP and the levels of ASAFR, MDA, p47^phox,ACE2, Ang(1–7), MasR, AngII and TH-positive nerves were increased (all P < 0.05) in myocardial infracted dogs; meanwhile, LVEF, FS, LVSP and SOD expression were decreased (all P < 0.05). However, after RDN therapy, these changes were significantly improved (P < 0.05), except that there were no significant differences observed in FS or LVSP between the two groups (P = 0.092 and 0.931, respectively). Importantly, the expression of TH, AngII and Ang(1–7) was positively correlated with MDA and negatively correlated with SOD. Between-group comparisons demonstrated no differences in serum creatinine (P = 0.706).

Conclusions

RDN attenuated cardiac remodelling and improved heart function by decreasing the level of cardiac oxidative stress and the local activity of the SNS and RAS in cardiac tissues. Additionally, the safety of the RDN procedure was established, as no significant decrease in LVSP or rise in serum creatinine was observed in our study.

PLGA-PNIPAM Microspheres Loaded with the Gastrointestinal Nutrient NaB Ameliorate Cardiac Dysfunction by Activating Sirt3 in Acute Myocardial Infarction

Acute myocardial infarction (AMI) is the death of cardiomyocytes caused by a lack of energy due to ischemia. Nutrients supplied by the blood are the main source of cellular energy for cardiomyocytes. Sodium butyrate (NaB), a gastrointestinal nutrient, is a short-chain fatty acid (butyric acid) that may act as an energy source in AMI therapy. Poly(lactic-co-glycolic acid)-Poly (N-isopropylacrylamide) microspheres loaded with NaB (PP-N) are synthesized to prolong the release of NaB and are injected into ischemic zones in a Sprague-Dawley rat AMI model. Here, this study shows that PP-N can significantly ameliorate cardiac dysfunction in AMI, and NaB can specially bind to Sirt3 structure, activating its deacetylation ability and inhibiting the generation of reactive oxygen species, autophagy, and angiogenesis promotion. The results indicate that NaB, acting as a nutrient, can protect cardiomyocytes in AMI. These results suggest that the gastrointestinal nutrient NaB may be a new therapy for AMI treatment, and PP-N may be the ideal therapeutic regimen.

Targeting acetaldehyde dehydrogenase 2 (ALDH2) in heart failure-Recent insights and perspectives

Heart failure is one of the major causes of the ever-rising mortality globally. ALDH2 rs671 polymorphism is proven to be closely related to the prevalence of CAD, hypertension, diabetes mellitus and alcoholism, which are etiological factors of heart failure. In addition, growing evidence supports a possible role for ALDH2 in different forms of heart failure. In this mini-review, we will review the recent insights regarding the effects of ALDH2 polymorphism on etiological factors of heart failure and underlying mechanisms involved. In addition, we will also discuss the booming epigenetic information in this field which will greatly improve our understanding of the cardiovascular effect of ALDH2. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure edited by Dr. Jun Ren & Yingmei Zhang.

Cell-specific effects of Nox2 on the acute and chronic response to myocardial infarction

Background

Increased reactive oxygen species (ROS) production is involved in the process of adverse cardiac remodeling and development of heart failure after myocardial infarction (MI). NADPH oxidase-2 (Nox2) is a major ROS source within the heart and its activity increases after MI. Furthermore, genetic deletion of Nox2 is protective against post-MI cardiac remodeling. Nox2 levels may increase both in cardiomyocytes and endothelial cells and recent studies indicate cell-specific effects of Nox2, but it is not known which of these cell types is important in post-MI remodeling.

Methods and results

We have generated transgenic mouse models in which Nox2 expression is targeted either to cardiomyocytes (cardio-Nox2TG) or endothelial cells (endo-Nox2TG). We here studied the response of cardio-Nox2TG mice, endo-Nox2TG mice and matched wild-type littermates (WT) to MI induced by permanent left coronary artery ligation up to 4 weeks. Initial infarct size assessed by magnetic resonance imaging (MRI) and cardiac dysfunction were similar among groups. Cardiomyocyte hypertrophy and interstitial fibrosis were augmented in cardio-Nox2TG compared to WT after MI and post-MI survival tended to be worse whereas endo-Nox2TG mice showed no significant difference compared to WT.

Conclusions

These results indicate that cardiomyocyte rather than endothelial cell Nox2 may have the more important role in post-MI remodeling.

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ROS contribute to adverse cardiac remodeling after myocardial infarction (MI).

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Nox2 is a major cardiac ROS source but with cell-specific effects.

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Increased Nox2 in cardiomyocytes augments hypertrophy and fibrosis post-MI.

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Increased Nox2 in endothelium has no significant effect on cardiac remodeling after MI.

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Cardiomyocyte Nox2 may have the more important role in post-MI remodeling.

Role of Renal Oxidative Stress in the Pathogenesis of the Cardiorenal Syndrome

Renal dysfunction and heart failure commonly co-exist; it is termed the cardiorenal syndrome (CRS). This combination of renal and cardiac impairment presents a substantial clinical challenge and is associated with adverse prognosis. The pathogenesis of the CRS is complex, including chronic activation of the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system, together with reduced renal perfusion. Chronic activation of the RAAS can impair mitochondrial function, and increase mitochondrial derived oxidative stress which in turn can lead to renal injury and sodium and water retention. For example, it has been shown that exogenous Ang II augments renal mitochondrial oxidative stress, reduces GFR and induces albuminuria in rats with heart failure. Administration of Ang II also augmented renal mitochondrial dysfunction in aged mice. Current treatments for CRS, including angiotensin-converting enzyme inhibitors, exert limited renal protection if any at all. Therefore, novel treatments particularly those that can target renal mechanisms downstream to chronic activation of the renal renin-angiotensin system are likely to exert renoprotection in the setting of CRS.

A computational model of cardiac fibroblast signaling predicts context-dependent drivers of myofibroblast differentiation

Cardiac fibroblasts support heart function, and aberrant fibroblast signaling can lead to fibrosis and cardiac dysfunction. Yet how signaling molecules drive myofibroblast differentiation and fibrosis in the complex signaling environment of cardiac injury remains unclear. We developed a large-scale computational model of cardiac fibroblast signaling in order to identify regulators of fibrosis under diverse signaling contexts. The model network integrates 10 signaling pathways, including 91 nodes and 134 reactions, and it correctly predicted 80% of independent previous experiments. The model predicted key fibrotic signaling regulators (e.g. reactive oxygen species, tissue growth factor β (TGFβ) receptor), whose function varied depending on the extracellular environment. We characterized how network structure relates to function, identified functional modules, and predicted cross-talk between TGFβ and mechanical signaling, which was validated experimentally in adult cardiac fibroblasts. This study provides a systems framework for predicting key regulators of fibroblast signaling across diverse signaling contexts.

The experimental model of transition from compensated cardiac hypertrophy to failure created by transverse aortic constriction in mice

Background

Transverse aortic constriction (TAC) operation is used as an experimental model of left ventricular (LV) hypertrophy and LV failure in mice. The severity of LV remodeling or failure may depend on the degree of TAC, but is variable among operated animals. Therefore, we tried to identify the optimal diameter of TAC to create this model with ease and high reproducibility.

Methods and results

To produce TAC in C57BL/6J mice (7–9 weeks, body weight 19–26 g, n = 109), a 7–0 nylon suture ligature was tightly tied around the transverse aorta against needles with 3 different diameters (mm); 0.40, 0.385 and 0.375. LV wall thickness, end-diastolic dimension, fractional shortening were measured by echocardiography. At 4 weeks after TAC, no mouse with the 0.400 mm gauge progressed in LV failure. The 0.385 mm pin gauge mouse kept a more survival rate compared with the 0.375 mm (59% vs 48%), representing same efficient in LV failure. With the 0.385 mm pin gauge, hearts of mice remained LV hypertrophy at 1 week after TAC, followed by LV failure at 4 weeks.

Conclusion

TAC with the diameter of 0.385 mm can effectively induce the transition from LV hypertrophy to failure in mice with relatively preserved survival.

Direct renin inhibitor ameliorates insulin resistance by improving insulin signaling and oxidative stress in the skeletal muscle from post-infarct heart failure in mice

Insulin resistance can occur as a consequence of heart failure (HF). Activation of the renin-angiotensin system (RAS) may play a crucial role in this phenomenon. We thus investigated the effect of a direct renin inhibitor, aliskiren, on insulin resistance in HF after myocardial infarction (MI). MI and sham operation were performed in male C57BL/6J mice. The mice were divided into 4 groups and treated with sham-operation (Sham, n=10), sham-operation and aliskiren (Sham+Aliskiren; 10mg/kg/day, n=10), MI (n=11), or MI and aliskiren (MI+Aliskiren, n=11). After 4 weeks, MI mice showed left ventricular dilation and dysfunction, which were not affected by aliskiren. The percent decrease of blood glucose after insulin load was significantly smaller in MI than in Sham (14±5% vs. 36±2%), and was ameliorated in MI+Aliskiren (34±5%) mice. Insulin-stimulated serine-phosphorylation of Akt and glucose transporter 4 translocation were decreased in the skeletal muscle of MI compared to Sham by 57% and 69%, and both changes were ameliorated in the MI+Aliskiren group (91% and 94%). Aliskiren administration in MI mice significantly inhibited plasma renin activity and angiotensin II (Ang II) levels. Moreover, (pro)renin receptor expression and local Ang II production were upregulated in skeletal muscle from MI and were attenuated in MI+Aliskiren mice, in tandem with a decrease in superoxide production and NAD(P)H oxidase activities. In conclusion, aliskiren ameliorated insulin resistance in HF by improving insulin signaling in the skeletal muscle, at least partly by inhibiting systemic and (pro)renin receptor-mediated local RAS activation, and subsequent NAD(P)H oxidase-induced oxidative stress.

Cell Therapy in Ischemic Heart Disease: Interventions That Modulate Cardiac Regeneration

The incidence of severe ischemic heart disease caused by coronary obstruction has progressively increased. Alternative forms of treatment have been studied in an attempt to regenerate myocardial tissue, induce angiogenesis, and improve clinical conditions. In this context, cell therapy has emerged as a promising alternative using cells with regenerative potential, focusing on the release of paracrine and autocrine factors that contribute to cell survival, angiogenesis, and tissue remodeling. Evidence of the safety, feasibility, and potential effectiveness of cell therapy has emerged from several clinical trials using different lineages of adult stem cells. The clinical benefit, however, is not yet well established. In this review, we discuss the therapeutic potential of cell therapy in terms of regenerative and angiogenic capacity after myocardial ischemia. In addition, we addressed nonpharmacological interventions that may influence this therapeutic practice, such as diet and physical training. This review brings together current data on pharmacological and nonpharmacological approaches to improve cell homing and cardiac repair.

Regulation of mitochondrial oxidative stress by β-arrestins in cultured human cardiac fibroblasts

Oxidative stress in cardiac fibroblasts (CFs) promotes transformation to myofibroblasts and collagen synthesis leading to myocardial fibrosis, a precursor to heart failure (HF). NADPH oxidase 4 (Nox4) is a major source of cardiac reactive oxygen species (ROS); however, mechanisms of Nox4 regulation are unclear. β-arrestins are scaffold proteins that signal in G-protein-dependent and -independent pathways; for example, in ERK activation. We hypothesize that β-arrestins regulate oxidative stress in a Nox4-dependent manner and increase fibrosis in HF. CFs were isolated from normal and failing adult human left ventricles. Mitochondrial ROS/superoxide production was quantitated using MitoSox. β-arrestin and Nox4 expressions were manipulated using adenoviral overexpression or short interfering RNA (siRNA)-mediated knockdown. Mitochondrial oxidative stress and Nox4 expression in CFs were significantly increased in HF. Nox4 knockdown resulted in inhibition of mitochondrial superoxide production and decreased basal and TGF-β-stimulated collagen and α-SMA expression. CF β-arrestin expression was upregulated fourfold in HF. β-arrestin knockdown in failing CFs decreased ROS and Nox4 expression by 50%. β-arrestin overexpression in normal CFs increased mitochondrial superoxide production twofold. These effects were prevented by inhibition of either Nox or ERK. Upregulation of Nox4 seemed to be a primary mechanism for increased ROS production in failing CFs, which stimulates collagen deposition. β-arrestin expression was upregulated in HF and plays an important and newly identified role in regulating mitochondrial superoxide production via Nox4. The mechanism for this effect seems to be ERK-mediated. Targeted inhibition of β-arrestins in CFs might decrease oxidative stress as well as pathological cardiac fibrosis.

Summary: β-arrestins regulate oxidative stress in a Nox4-dependent manner leading to increased extracellular-matrix protein synthesis by cardiac fibroblasts (CFs). Targeted inhibition of β-arrestins in CFs might decrease pathological fibrosis.

Traditional Chinese medicine Qili qiangxin inhibits cardiomyocyte apoptosis in rats following myocardial infarction

The aim of the present study was to examine the effect of the traditional Chinese medicine Qili qiangxin on cardiomyocyte apoptosis following myocardial infarction (MI) in a rat model. MI was induced in rats by ligation of the anterior descending coronary artery. Survivors were randomly divided into the sham operation, MI, and Qili qiangxin groups (4 g/kg per day). After 28 days, infarction size was measured. In the non-infarcted zones (NIZ), the apoptotic index (AI) was measured by terminal deoxynucleotidyl transferase (TdT)-mediated digoxigenin-conjugated dUTP nick-end labeling (TUNEL). Expression of Fas was detected by immunohistochemistry, and the expression of xanthine oxidase (XO) and caspase-3 by western blot analysis. In addition, the XO and ^·O₂⁻, ^·OH-scavenging activity of myocardial tissue in NIZ was measured by colorimetry. Compared to the MI group, AI and the expression of Fas and caspase-3 were significantly decreased in NIZ. The activity of XO was also considerably reduced while ^·O₂⁻ and ^·OH-scavenging activity was significantly increased in the Qili qiangxin group. Ventricular remodeling was attenuated but there were no significant differences in infarct size (IS) or XO expression levels between the Qili qiangxin and MI groups. In conclusion, the results suggest that Qili qiangxin may inhibit cardiomyocyte apoptosis in NIZ in rats. The potential mechanism involved may be associated with its ability to reduce reactive oxygen species (ROS) and to depress the expression of Fas and caspase-3.

Role of sodium and calcium dysregulation in tachyarrhythmias in sudden cardiac death

Despite improvements in the therapy of underlying heart disease, sudden cardiac death is a major cause of death worldwide. Disturbed Na and Ca handling is known to be a major predisposing factor for life-threatening tachyarrhythmias. In cardiomyocytes, many ion channels and transporters, including voltage-gated Na and Ca channels, cardiac ryanodine receptors, Na/Ca-exchanger, and SR Ca-ATPase are involved in this regulation. We have learned a lot about the pathophysiological relevance of disturbed ion channel function from monogenetic disorders. Changes in the gating of a single ion channel and the activity of an ion pump suffice to dramatically increase the propensity for arrhythmias even in structurally normal hearts. Nevertheless, patients with heart failure with acquired dysfunction in many ion channels and transporters exhibit profound dysregulation of Na and Ca handling and Ca/calmodulin-dependent protein kinase and are especially prone to arrhythmias. A deeper understanding of the underlying arrhythmic principles is mandatory if we are to improve their outcome. This review addresses basic tachyarrhythmic mechanisms, the underlying ionic mechanisms and the consequences for ion homeostasis, and the situation in complex diseases like heart failure.

A New Therapeutic Modality for Acute Myocardial Infarction: Nanoparticle-Mediated Delivery of Pitavastatin Induces Cardioprotection from Ischemia-Reperfusion Injury via Activation of PI3K/Akt Pathway and Anti-Inflammation in a Rat Model

Aim

There is an unmet need to develop an innovative cardioprotective modality for acute myocardial infarction (AMI), for which the effectiveness of interventional reperfusion therapy is hampered by myocardial ischemia-reperfusion (IR) injury. Pretreatment with statins before ischemia is shown to reduce MI size in animals. However, no benefit was found in animals and patients with AMI when administered at the time of reperfusion, suggesting insufficient drug targeting into the IR myocardium. Here we tested the hypothesis that nanoparticle-mediated targeting of pitavastatin protects the heart from IR injury.

Methods and Results

In a rat IR model, poly(lactic acid/glycolic acid) (PLGA) nanoparticle incorporating FITC accumulated in the IR myocardium through enhanced vascular permeability, and in CD11b-positive leukocytes in the IR myocardium and peripheral blood after intravenous treatment. Intravenous treatment with PLGA nanoparticle containing pitavastatin (Pitavastatin-NP, 1 mg/kg) at reperfusion reduced MI size after 24 hours and ameliorated left ventricular dysfunction 4-week after reperfusion; by contrast, pitavastatin alone (as high as 10 mg/kg) showed no therapeutic effects. The therapeutic effects of Pitavastatin-NP were blunted by a PI3K inhibitor wortmannin, but not by a mitochondrial permeability transition pore inhibitor cyclosporine A. Pitavastatin-NP induced phosphorylation of Akt and GSK3β, and inhibited inflammation and cardiomyocyte apoptosis in the IR myocardium.

Conclusions

Nanoparticle-mediated targeting of pitavastatin induced cardioprotection from IR injury by activation of PI3K/Akt pathway and inhibition of inflammation and cardiomyocyte death in this model. This strategy can be developed as an innovative cardioprotective modality that may advance currently unsatisfactory reperfusion therapy for AMI.