Cholesterol lowering attenuates pressure overload-induced heart failure in mice with mild hypercholesterolemia

Effects of Thymoquinone Alone or in Combination with Losartan on the Cardiotoxicity Caused by Oxidative Stress and Inflammation in Hypercholesterolemia

Dietary cholesterol accelerates oxidative and pro-inflammatory processes, causing hypercholesterolemia and cardiovascular diseases. Thus, the purpose of the current study is to compare the protective effects of thymoquinone (TQ) alone or in combination with losartan (LT) against the heart damage caused by a high-cholesterol diet (HCD). HCD-fed rat groups revealed an elevated activity of indicators of cardiac enzymes in the serum. Serum and cardiac lipids were also found to be significantly higher in HCD-fed rat groups. Cardiac pro-inflammatory and oxidative markers were also increased in HCD-fed rat groups, whereas antioxidant indicators were decreased. However, all of these biochemical, inflammatory, antioxidant, and oxidative change indicators returned to levels similar to those of normal rats after treatment with TQ alone or in combination with LT administered to HCD-fed rat groups. Hypercholesterolemia considerably induced the lipid peroxidation product, thiobarbituric acid reaction substances (TBARs), and oxidative radicals in cardiac cells, which were attenuated by QT and LT treatments, particularly when combined. Finally, QT, LT, and their combination were able to reduce the histological changes changes brought on by cholesterol excess in cardiac tissues. In conclusion, administration of TQ in a combination with LT which has a better protective effect, significantly reduced the hypercholesterolemic-induced oxidative and inflammatory changes that occurred in cardiac tissue.

Increased Remnant Lipoproteins in Apo E Deficient Mice Induce Coronary Atherosclerosis following Transverse Aortic Constriction and Aggravate the Development of Pressure Overload-Induced Cardiac Hypertrophy and Heart Failure

Murine coronary arteries are very resistant to the development of atherosclerosis, which may be related to their intramyocardial course. Blood pressure promotes atherosclerotic plaque formation by acting as a physical force that potentiates the migration of pro-atherogenic lipoproteins across the endothelium. C57BL/6N apolipoprotein (apo) E deficient mice have increased remnant lipoproteins that are a risk factor for coronary atherosclerosis. In this study, our aim was to quantify coronary atherosclerosis and artery remodeling following transverse aortic constriction (TAC) in C57BL/6N apo E−/− mice and to evaluate the impact of increased remnant lipoproteins on the development of pressure overload-induced cardiac hypertrophy and heart failure. Advanced atherosclerotic lesions were observed in the left coronary artery of C57BL/6N apo E−/− TAC mice but not in C57BL/6N TAC mice. Pressure overload resulted in markedly increased cardiac hypertrophy and more pronounced heart failure in C57BL/6N apo E−/− TAC mice in comparison to C57BL/6N TAC mice. Pathological hypertrophy, as evidenced by increased myocardial fibrosis and capillary rarefaction, was more prominent in C57BL/6N TAC apo E−/− than in C57BL/6N TAC mice and led to more marked cardiac dysfunction. In conclusion, TAC in apo E deficient mice induces coronary atherosclerosis and aggravates the development of pathological cardiac hypertrophy and heart failure.

Diet-Induced Hypercholesterolemia Leads to Cardiac Dysfunction and Alterations in the Myocardial Proteome

Elevated blood cholesterol is a major risk factor for coronary heart disease. Moreover, direct effects on the myocardium also contribute to the adverse effects of hypercholesterolemia. Here, we investigated the effect of hypercholesterolemia on the cardiac proteome. Male Wistar rats were fed with a laboratory rodent chow supplemented with 2% cholesterol for 8 weeks to induce hypercholesterolemia. The protein expression data obtained from the proteomic characterization of left ventricular samples from normo- and hypercholesterolemic animals were subjected to gene ontology (GO) and protein interaction analyses. Elevated circulating cholesterol levels were accompanied by diastolic dysfunction in cholesterol-fed rats. The proteomic characterization of left ventricular samples revealed altered expression of 45 proteins due to hypercholesterolemia. Based on the Gene Ontology analysis, hypercholesterolemia was associated with disturbed expression of cytoskeletal and contractile proteins. Beta-actin was downregulated in the hypercholesterolemic myocardium, and established a prominent hub of the protein interaction network. Analysis of the unfiltered dataset revealed concordant downregulated expression patterns in proteins associated with the arrangement of the contractile system (e.g., cardiac-specific troponins and myosin complex), and in subunits of the mitochondrial respiratory chain. We conclude that the observed changes in the cardiac proteome may contribute to the development of diastolic dysfunction in hypercholesterolemia.

New Progress in the Molecular Regulations and Therapeutic Applications in Cardiac Oxidative Damage Caused by Pressure Overload

Chronic pressure overload is a key risk factor for mortality due to its subsequent development of heart failure, in which the underlying molecular mechanisms remain vastly undetermined. In this review, we updated the latest advancements for investigating the role and relevant mechanisms of oxidative stress involved in the pathogenesis of pressure-overload-induced cardiomyopathy and cardiac dysfunction, focusing on significant biological sources of reactive oxygen species (free radical) production, antioxidant defenses, and their association with the cardiac metabolic remodeling in the stressed heart. We also summarize the newly developed preclinical therapeutic approaches in animal models for pressure-overload-induced myocardial damage. This review aims to enhance the current understanding of the mechanisms of chronic hypertensive heart failure and potentially improve the development of better therapeutic strategies for the associated diseases.

D, Banerjee SK, Konar A, Bandyopadhyay A. Downregulation of PTEN Promotes Autophagy via Concurrent Reduction in Apoptosis in Cardiac Hypertrophy in PPAR α−/− Mice

Cardiac hypertrophy is characterized by an increase in the size of the cardiomyocytes which is initially triggered as an adaptive response but ultimately becomes maladaptive with chronic exposure to different hypertrophic stimuli. Prolonged cardiac hypertrophy is often associated with mitochondrial dysfunctions and cardiomyocyte cell death. Peroxisome proliferator activated receptor alpha (PPAR α), which is critical for mitochondrial biogenesis and fatty acid oxidation, is down regulated in hypertrophied cardiomyocytes. Yet, the role of PPAR α in cardiomyocyte death is largely unknown. To assess the role of PPAR α in chronic hypertrophy, isoproterenol, a β-adrenergic receptor agonist was administered in PPAR α knock out (PPAR α−/−) mice for 2 weeks and hypertrophy associated changes in cardiac tissues were observed. Echocardiographic analysis ensured the development of cardiac hypertrophy and compromised hemodynamics in PPAR α−/− mice. Proteomic analysis using high resolution mass spectrometer identified about 1,200 proteins enriched in heart tissue. Proteins were classified according to biological pathway and molecular functions. We observed an unexpected down regulation of apoptotic markers, Annexin V and p53 in hypertrophied heart tissue. Further validation revealed a significant down regulation of apoptosis regulator, PTEN, along with other apoptosis markers like p53, Caspase 9 and c-PARP. The autophagy markers Atg3, Atg5, Atg7, p62, Beclin1 and LC3 A/B were up regulated in PPAR α−/− mice indicating an increase in autophagy. Similar observations were made in a high cholesterol diet fed PPAR α−/−mice. The results were further validated in vitro using NRVMs and H9C2 cell line by blocking PPAR α that resulted in enhanced autophagosome formation upon hypertrophic stimulation. The results demonstrate that in the absence of PPAR α apoptotic pathway is inhibited while autophagy is enhanced. The data suggest that PPAR α signaling might act as a molecular switch between apoptosis and autophagy thereby playing a critical role in adaptive process in cardiac hypertrophy.

Role of Oxidative Stress in Heart Failure: Insights from Gene Transfer Studies

Under physiological circumstances, there is an exquisite balance between reactive oxygen species (ROS) production and ROS degradation, resulting in low steady-state ROS levels. ROS participate in normal cellular function and in cellular homeostasis. Oxidative stress is the state of a transient or a persistent increase of steady-state ROS levels leading to disturbed signaling pathways and oxidative modification of cellular constituents. It is a key pathophysiological player in pathological hypertrophy, pathological remodeling, and the development and progression of heart failure. The heart is the metabolically most active organ and is characterized by the highest content of mitochondria of any tissue. Mitochondria are the main source of ROS in the myocardium. The causal role of oxidative stress in heart failure is highlighted by gene transfer studies of three primary antioxidant enzymes, thioredoxin, and heme oxygenase-1, and is further supported by gene therapy studies directed at correcting oxidative stress linked to metabolic risk factors. Moreover, gene transfer studies have demonstrated that redox-sensitive microRNAs constitute potential therapeutic targets for the treatment of heart failure. In conclusion, gene therapy studies have provided strong corroborative evidence for a key role of oxidative stress in pathological remodeling and in the development of heart failure.

Apolipoprotein E4 Is Associated with Right Ventricular Dysfunction in Dilated Cardiomyopathy-An Animal and In-Human Comparative Study

ApoE abnormality represents a well-known risk factor for cardiovascular diseases. Beyond its role in lipid metabolism, novel studies demonstrate a complex involvement of apoE in membrane homeostasis and signaling as well as in nuclear transcription. Due to the large spread of apoE isoforms in the human population, there is a need to understand the apoE’s role in pathological processes. Our study aims to dissect the involvement of apoE in heart failure. We showed that apoE-deficient rats present multiple organ damages (kidney, liver, lung and spleen) besides the known predisposition for obesity and affected lipid metabolism (two-fold increase in tissular damages in liver and one-fold increase in kidney, lung and spleen). Heart tissue also showed significant morphological changes in apoE^−/− rats, mostly after a high-fat diet. Interestingly, the right ventricle of apoE^−/− rats fed a high-fat diet showed more damage and affected collagen content (~60% less total collagen content and double increase in collagen1/collagen3 ratio) compared with the left ventricle (no significant differences in total collagen content or collagen1/collagen3 ratio). In patients, we were able to find a correlation between the presence of ε4 allele and cardiomyopathy (χ² = 10.244; p = 0.001), but also with right ventricle dysfunction with decreased TAPSE (15.3 ± 2.63 mm in ε4-allele-presenting patients vs. 19.8 ± 3.58 mm if the ε4 allele is absent, p < 0.0001*) and increased in systolic pulmonary artery pressure (50.44 ± 16.47 mmHg in ε4-allele-presenting patients vs. 40.68 ± 15.94 mmHg if the ε4 allele is absent, p = 0.0019). Our results confirm that the presence of the ε4 allele is a lipid-metabolism-independent risk factor for heart failure. Moreover, we show for the first time that the presence of the ε4 allele is associated with right ventricle dysfunction, implying different regulatory mechanisms of fibroblasts and the extracellular matrix in both ventricles. This is essential to be considered and thoroughly investigated before the design of therapeutical strategies for patients with heart failure.

Renin angiotensin system blockage by losartan neutralize hypercholesterolemia-induced inflammatory and oxidative injuries

Objectives: This study explores the protective role of losartan (LT) against oxidative and inflammatory damages in different physiological systems including heart, liver, and kidney tissue in hypercholesterolemic rats.

Methods: After induction of hypercholesterolemia by high cholesterol diet for 6 weeks, LT was administered for 4 weeks. In serum, the levels of lipoproteins, aminotransferases, creatine kinases, urea, apoptosis, and inflammatory markers were measured. In cardiac, hepatic, and renal tissues, lipid peroxidation product and GSH as well as antioxidant enzymatic activities were assayed. Finally, histopathological assessment evaluated the structural damage in cardiac, hepatic, and renal tissues.

Results: Serum markers of cardiac, hepatic, and renal toxicities including creatine kinases, aminotransferases, and urea were attenuated by LT in hypercholesterolemic animals. Moreover, LT markedly corrected the elevated levels of lipoproteins, apoptosis, and inflammatory biomarkers. Hypercholesterolemia-induced lipid peroxidation, low GSH levels, and diminished activities of antioxidant enzymes were prominently improved in LT treated animals. Histopathological alterations by hypercholesterolemia in heart, liver, and kidney tissues were ameliorated by LT.

Conclusion: This study confirmed the pathological enrollment of renin–angiotensin system in hypercholesterolemia-associated metabolic alterations. LT had a significant cardiac, hepatic, and renal protective role against these impairments through down-regulation of oxidative damage, inflammation and necrosis.

Allyl Methyl Sulfide Preserved Pressure Overload-Induced Heart Failure Via Modulation of Mitochondrial Function

BACKGROUND

Cardiovascular diseases are the leading cause of death globally, and they are causing enormous socio-economic burden to the developed and developing countries. Allyl Methyl Sulfide (AMS) is a novel cardioprotective metabolite identified in the serum of rats after raw garlic administration. The present study explored the cardioprotective effect of AMS on thoracic aortic constriction (TAC)-induced cardiac hypertrophy and heart failure model in rats.

METHODS

Thoracic aortic constriction (TAC) by titanium ligating clips resulted in the development of pressure overload-induced cardiac hypertrophy and heart failure model. Four weeks prior to TAC and for 8 weeks after TAC, Sprague Dawley (SD) rats were administered with AMS (25 and 50 mg/kg/day) or Enalapril (10 mg/kg/day).

RESULTS

We have observed AMS (25 and 50 mg/kg/day) intervention significantly improved structural and functional parameters of the heart. mRNA expression of fetal genes i.e., atrial natriuretic peptide (ANP), alpha skeletal actin (α-SA) and beta myosin heavy chain (β-MHC) were reduced in AMS treated TAC hearts along with decrease in perivascular and interstitial fibrosis. AMS attenuated lipid peroxidation and improved protein expression of endogenous antioxidant enzymes i.e., catalase and manganese superoxide dismutase (MnSOD) along with electron transport chain (ETC) complex activity. AMS increased mitochondrial fusion proteins i.e., mitofusin 1 (MFN1), mitofusin 2 (MFN2) and optic atrophy protein (OPA1), and reduced fission protein i.e., dynamin-related protein 1 (DRP1). Preliminary study suggests that AMS intervention upregulated genes involved in mitochondrial bioenergetics in normal rats. Further, in-vitro studies suggest that AMS reduced mitochondrial reactive oxygen species (ROS), preserved mitochondrial membrane potential and oxygen consumption rate (OCR) in isoproterenol-treated cardiomyoblast.

CONCLUSION

This study demonstrated that AMS protected cardiac remodelling, LV dysfunction and fibrosis in pressure overload-induced cardiac hypertrophy and heart failure model by improving endogenous antioxidants and mitochondrial function.

Water-soluble alkaloids extracted from Aconiti Radix lateralis praeparata protect against chronic heart failure in rats via a calcium signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Many studies have shown the beneficial effects of aconite water-soluble alkaloid extract (AWA) in experimental models of heart disease, which have been ascribed to the presence of aconine, hypaconine, talatisamine, fuziline, neoline, and songorine. This study evaluated the effects of a chemically characterized AWA by chemical content, evaluated its effects in suprarenal abdominal aortic coarctation surgery (AAC)-induced chronic heart failure (CHF) in rats, and revealed the underlying mechanisms of action by proteomics.

METHODS

Rats were distributed into different groups: sham, model, and AWA-treated groups (10, 20, and 40 mg/kg/day). Sham rats received surgery without AAC, whereas model rats an AWA-treated groups underwent AAC surgery. after 8 weeks, the treatment group was fed AWA for 4 weeks, and body weight was assessed weekly. At the end of the treatment, heart function was tested by echocardiography. AAC-induced chronic heart failure, including myocardial fibrosis, cardiomyocyte hypertrophy, and apoptosis, was evaluated in heart tissue and plasma by RT-qPCR, ELISA, hematoxylin and eosin (H&E) staining, Masson's trichrome staining, TUNEL staining, and immunofluorescence staining of α-SMA, Col Ⅰ, and Col Ⅲ. Then, a proteomics approach was used to explore the underlying mechanisms of action of AWA in chronic heart failure.

RESULTS

AWA administration reduced body weight gain, myocardial fibrosis, cardiomyocyte hypertrophy, and apoptosis, and rats showed improvement in cardiac function compared to model group. The extract significantly ameliorated the AAC-induced altered expression of heart failure markers such as ANP, NT-proBNP, and β-MHC, as well as fibrosis, hypertrophy markers MMP-2 and MMP-9, and other heart failure-related factors including plasma levels of TNF-α and IL-6. Furthermore, the extract reduced the protein expression of α-SMA, Col Ⅰ, and Col Ⅲ in the left ventricular (LV), thus inhibiting the LV remodeling associated with CHF. In addition, proteomics characterization of differentially expressed proteins showed that AWA administration inhibited left ventricular remodeling in CHF rats via a calcium signaling pathway, and reversed the expression of RyR2 and SERCA2a.

CONCLUSIONS

AWA extract exerts beneficial effects in an AAC-induced CHF model in rats, which was associated with an improvement in LV function, hypertrophy, fibrosis, and apoptotic status. These effects may be related to the regulation of calcium signaling by the altered expression of RyR2 and SERCA2a.

High-Density Lipoprotein-Targeted Therapies for Heart Failure

The main and common constituents of high-density lipoproteins (HDLs) are apolipoprotein A-I, cholesterol, and phospholipids. Biochemical heterogeneity of HDL particles is based on the variable presence of one or more representatives of at least 180 proteins, 200 lipid species, and 20 micro RNAs. HDLs are circulating multimolecular platforms that perform divergent functions whereby the potential of HDL-targeted interventions for treatment of heart failure can be postulated based on its pleiotropic effects. Several murine studies have shown that HDLs exert effects on the myocardium, which are completely independent of any impact on coronary arteries. Overall, HDL-targeted therapies exert a direct positive lusitropic effect on the myocardium, inhibit the development of cardiac hypertrophy, suppress interstitial and perivascular myocardial fibrosis, increase capillary density in the myocardium, and prevent the occurrence of heart failure. In four distinct murine models, HDL-targeted interventions were shown to be a successful treatment for both pre-existing heart failure with reduced ejection fraction (HFrEF) and pre-existing heart failure with preserved ejection fraction (HFrEF). Until now, the effect of HDL-targeted interventions has not been evaluated in randomized clinical trials in heart failure patients. As HFpEF represents an important unmet therapeutic need, this is likely the preferred therapeutic domain for clinical translation.