Fabio Magliulo

Genetic Deletion of Uncoupling Protein 3 Exaggerates Apoptotic Cell Death in the Ischemic Heart Leading to Heart Failure

Background Uncoupling protein 3 (ucp3) is a member of the mitochondrial anion carrier superfamily of proteins uncoupling mitochondrial respiration. In this study, we investigated the effects of ucp3 genetic deletion on mitochondrial function and cell survival under low oxygen conditions in vitro and in vivo. Methods and Results To test the effects of ucp3 deletion in vitro, murine embryonic fibroblasts and adult cardiomyocytes were isolated from wild‐type (WT, n=67) and ucp3 knockout mice (ucp3−/−, n=70). To test the effects of ucp3 genetic deletion in vivo, myocardial infarction (MI) was induced by permanent coronary artery ligation in WT and ucp3−/− mice. Compared with WT, ucp3−/− murine embryonic fibroblasts and cardiomyocytes exhibited mitochondrial dysfunction and increased mitochondrial reactive oxygen species generation and apoptotic cell death under hypoxic conditions in vitro (terminal deoxynucleotidyl transferase‐dUTP nick end labeling–positive nuclei: WT hypoxia, 70.3±1.2%; ucp3−/− hypoxia, 85.3±0.9%; P<0.05). After MI, despite similar areas at risk in the 2 groups, ucp3−/− hearts demonstrated a significantly larger infarct size compared with WT (infarct area/area at risk: WT, 48.2±3.7%; ucp3−/−, 65.0±2.9%; P<0.05). Eight weeks after MI, cardiac function was significantly decreased in ucp3−/− mice compared with WT (fractional shortening: WT MI, 42.7±3.1%; ucp3−/− MI, 24.4±2.9; P<0.05), and this was associated with heightened apoptotic cell death (terminal deoxynucleotidyl transferase‐dUTP nick end labeling–positive nuclei: WT MI, 0.7±0.04%; ucp3−/− MI, 1.1±0.09%, P<0.05). Conclusions Our data indicate that ucp3 levels regulate reactive oxygen species levels and cell survival during hypoxia, modulating infarct size in the ischemic heart.

Epigenetic Switch at Atp2a2 and Myh7 Gene Promoters in Pressure Overload-Induced Heart Failure

Re-induction of fetal genes and/or re-expression of postnatal genes represent hallmarks of pathological cardiac remodeling, and are considered important in the progression of the normal heart towards heart failure (HF). Whether epigenetic modifications are involved in these processes is currently under investigation. Here we hypothesized that histone chromatin modifications may underlie changes in the gene expression program during pressure overload-induced HF. We evaluated chromatin marks at the promoter regions of the sarcoplasmic reticulum Ca2+ATPase (SERCA-2A) and β-myosin-heavy chain (β-MHC) genes (Atp2a2 and Myh7, respectively) in murine hearts after one or eight weeks of pressure overload induced by transverse aortic constriction (TAC). As expected, all TAC hearts displayed a significant reduction in SERCA-2A and a significant induction of β-MHC mRNA levels. Interestingly, opposite histone H3 modifications were identified in the promoter regions of these genes after TAC, including H3 dimethylation (me2) at lysine (K) 4 (H3K4me2) and K9 (H3K9me2), H3 trimethylation (me3) at K27 (H3K27me3) and dimethylation (me2) at K36 (H3K36me2). Consistently, a significant reduction of lysine-specific demethylase KDM2A could be found after eight weeks of TAC at the Atp2a2 promoter. Moreover, opposite changes in the recruitment of DNA methylation machinery components (DNA methyltransferases DNMT1 and DNMT3b, and methyl CpG binding protein 2 MeCp2) were found at the Atp2a2 or Myh7 promoters after TAC. Taken together, these results suggest that epigenetic modifications may underlie gene expression reprogramming in the adult murine heart under conditions of pressure overload, and might be involved in the progression of the normal heart towards HF.

Cardiovascular effects of treadmill exercise in physiological and pathological preclinical settings

Exercise adaptations result from a coordinated response of multiple organ systems, including cardiovascular, pulmonary, endocrine-metabolic, immunologic, and skeletal muscle. Among these, the cardiovascular system is the most directly affected by exercise, and it is responsible for many of the important acute changes occurring during physical training. In recent years, the development of animal models of pathological or physiological cardiac overload has allowed researchers to precisely analyze the complex cardiovascular responses to stress in genetically altered murine models of human cardiovascular disease. The intensity-controlled treadmill exercise represents a well-characterized model of physiological cardiac hypertrophy because of its ability to mimic the typical responses to exercise in humans. In this review, we describe cardiovascular adaptations to treadmill exercise in mice and the most important parameters that can be used to quantify such modifications. Moreover, we discuss how treadmill exercise can be used to perform physiological testing in mouse models of disease and to enlighten the role of specific signaling pathways on cardiac function.

Dermcidin: a skeletal muscle myokine modulating cardiomyocyte survival and infarct size after coronary artery ligation

AIMS Coronary artery disease is the leading cause of death in western countries, and its association with lower extremity peripheral artery disease (LE-PAD) represents an independent predictor of worse outcome. However, the molecular mechanisms underlying these effects are currently unknown. METHODS AND RESULTS To investigate these processes, we used in vitro approaches and several mouse models: (i) unilateral limb ischaemia by left common femoral artery ligation [peripheral ischaemia (PI), n = 38]; (ii) myocardial infarction by permanent ligation of the left descending coronary artery (MI, n = 40); (iii) MI after 5 weeks of limb ischaemia (PI + MI, n = 44); (iv) sham operation (SHAM, n = 20). Compared with MI, PI + MI hearts were characterized by a significant increase in cardiomyocyte apoptosis, larger infarct areas, and decreased cardiac function. By using a proteomic approach, we identified a ≅ 8 kDa circulating peptide, Dermcidin (DCD), secreted by ischaemic skeletal muscles, enhancing cardiomyocytes apoptosis under hypoxic conditions and infarct size after permanent coronary artery ligation. siRNA interference experiments to reduce DCD circulating levels significantly reduced infarct size and ameliorated cardiac function after MI. CONCLUSION Our data demonstrate that chronic limb ischaemia activates detrimental pathways in the ischaemic heart through humoral mechanisms of remote organ crosstalk. Thus, DCD may represent a novel important myokine modulating cardiomyocyte survival and function.

Cardiac Side Effects of Chemotherapy: State of Art and Strategies for a Correct Management

In recent years, the development of more effective drugs has provided a better prognosis and an increase in life expectancy for patients at all-stages of cancer. On the other hand, the price for the improving effectiveness of therapies against malignant tumors is the development of severe and potentially life-threatening drug reactions. Among these, cardiac toxic effects have recently gained particular attention. The term cardiotoxicity includes many possible pathological manifestations, but the most frequent is the reduction in cardiac function, potentially leading to heart failure and death. Importantly, the development of cardiac dysfunction may occur immediately after drug administration, or after years. The purpose of this review is to discuss the clinical features of cardiotoxicity, its molecular basis and novel possible strategies to reduce the likelihood of serious cardiac complications.

Akap1 Deficiency Promotes Mitochondrial Aberrations and Exacerbates Cardiac Injury Following Permanent Coronary Ligation via Enhanced Mitophagy and Apoptosis.

A-kinase anchoring proteins (AKAPs) transmit signals cues from seven-transmembrane receptors to specific sub-cellular locations. Mitochondrial AKAPs encoded by the Akap1 gene have been shown to modulate mitochondrial function and reactive oxygen species (ROS) production in the heart. Under conditions of hypoxia, mitochondrial AKAP121 undergoes proteolytic degradation mediated, at least in part, by the E3 ubiquitin ligase Seven In-Absentia Homolog 2 (Siah2). In the present study we hypothesized that Akap1 might be crucial to preserve mitochondrial function and structure, and cardiac responses to myocardial ischemia. To test this, eight-week-old Akap1 knockout mice (Akap1-/-), Siah2 knockout mice (Siah2-/-) or their wild-type (wt) littermates underwent myocardial infarction (MI) by permanent left coronary artery ligation. Age and gender matched mice of either genotype underwent a left thoracotomy without coronary ligation and were used as controls (sham). Twenty-four hours after coronary ligation, Akap1-/- mice displayed larger infarct size compared to Siah2-/- or wt mice. One week after MI, cardiac function and survival were also significantly reduced in Akap1-/- mice, while cardiac fibrosis was significantly increased. Akap1 deletion was associated with remarkable mitochondrial structural abnormalities at electron microscopy, increased ROS production and reduced mitochondrial function after MI. These alterations were associated with enhanced cardiac mitophagy and apoptosis. Autophagy inhibition by 3-methyladenine significantly reduced apoptosis and ameliorated cardiac dysfunction following MI in Akap1-/- mice. These results demonstrate that Akap1 deficiency promotes cardiac mitochondrial aberrations and mitophagy, enhancing infarct size, pathological cardiac remodeling and mortality under ischemic conditions. Thus, mitochondrial AKAPs might represent important players in the development of post-ischemic cardiac remodeling and novel therapeutic targets.

Physical activity in the prevention of peripheral artery disease in the elderly

Aging is a well-known cardiovascular risk factor and cardiovascular diseases (CVD) are estimated to be the most common cause of death in the elderly. Peripheral arterial disease (PAD) represents an important clinical manifestation of CVD leading to increase morbidity and mortality, especially in elderly population. The correct management of PAD population includes the prevention of cardiovascular events and relief of symptoms, most commonly intermittent claudication. Progressive physical activity is an effective treatment to improve walking distance and to reduce mortality and cardiovascular events in patients with PAD, however the ability to effectively engage in physical activity often declines with increasing age. The maintenance and increase of reserve functional capacity are important concepts in the elderly population. Ultimately, the goal in participation of physical activity in the healthy elderly population is maintenance and development of physical functional reserve capacity. Therefore, for individuals suffering of PAD, appropriate physical activity in the form of supervised exercise may serve as a primary therapy. Although there are few direct comparisons of therapeutic exercise programs vs. pharmacological or surgical interventions, these increases in walking distance are greater than those reported for the most widely used agents for claudication, pentoxyphylline, and cilostazol. Despite a reduction in mortality and improvement of quality of life caused by physical activity in the PAD population, the molecular, cellular, and functional changes that occur during physical activity are not completely understood. Therefore, this review article aims at presenting an overview of recent established clinical and molecular findings addressing the role of physical activity on PAD in the older population.

The Murine Model of Mucopolysaccharidosis IIIB Develops Cardiopathies over Time Leading to Heart Failure.

Mucopolysaccharidosis (MPS) IIIB is a lysosomal disease due to the deficiency of the enzyme α-N-acetylglucosaminidase (NAGLU) required for heparan sulfate (HS) degradation. The disease is characterized by mild somatic features and severe neurological disorders. Very little is known on the cardiac dysfunctions in MPS IIIB. In this study, we used the murine model of MPS IIIB (NAGLU knockout mice, NAGLU-/-) in order to investigate the cardiac involvement in the disease. Echocardiographic analysis showed a marked increase in left ventricular (LV) mass, reduced cardiac function and valvular defects in NAGLU-/- mice as compared to wild-type (WT) littermates. The NAGLU-/- mice exhibited a significant increase in aortic and mitral annulus dimension with a progressive elongation and thickening of anterior mitral valve leaflet. A severe mitral regurgitation with reduction in mitral inflow E-wave-to-A-wave ratio was observed in 32-week-old NAGLU-/- mice. Compared to WT mice, NAGLU-/- mice exhibited a significantly lower survival with increased mortality observed in particular after 25 weeks of age. Histopathological analysis revealed a significant increase of myocardial fiber vacuolization, accumulation of HS in the myocardial vacuoles, recruitment of inflammatory cells and collagen deposition within the myocardium, and an increase of LV fibrosis in NAGLU-/- mice compared to WT mice. Biochemical analysis of heart samples from affected mice showed increased expression levels of cardiac failure hallmarks such as calcium/calmodulin-dependent protein kinase II, connexin43, α-smooth muscle actin, α-actinin, atrial and brain natriuretic peptides, and myosin heavy polypeptide 7. Furthermore, heart samples from NAGLU-/- mice showed enhanced expression of the lysosome-associated membrane protein-2 (LAMP2), and the autophagic markers Beclin1 and LC3 isoform II (LC3-II). Overall, our findings demonstrate that NAGLU-/- mice develop heart disease, valvular abnormalities and cardiac failure associated with an impaired lysosomal autophagic flux.

Transradial approach for the endovascular treatment of type I endoleak after aortic aneurysm repair: a case report

BackgroundEndovascular repair of aortic aneurysms (EVAR) is obtained through the positioning of an aortic stent-graft, which excludes the aneurysmatic dilation. Type I endoleak is the most common complication, and it is caused by an incompetent proximal or distal attachment site, causing the separation between the stent-graft and the native arterial wall, and in turn creating direct communication between the aneurysm sac and the systemic arterial circulation. Endoleak occurrence is associated with high intrasac pressures, and requires a quick repair to prevent abdominal aortic aneurysm rupture.Case presentationWe report the first case of a 80-year-old man undergoing percutaneous closure of a peri-graft endoleak (type I) by transcatheter embolization through radial arterial access.ConclusionThe transradial approach has been shown to be a safe and effective alternative to the traditional transfemoral approach. A decrease in vascular complications and improved patient comfort are the primary benefits of this technique in patients with previous EVAR.

Novel Molecular Approaches in Heart Failure: Seven Trans-Membrane Receptors Signaling in the Heart and Circulating Blood Leukocytes

Heart failure (HF) is the result of molecular, cellular, and structural changes induced by cardiac load or injury. A complex network of signaling pathways have been involved in the development and progression of cardiac dysfunction. In this review, we summarize the pivotal role of seven trans-membrane receptors (7TMRs), also called G-protein-coupled receptors (GPCRs), in HF. Moreover, we will discuss the current knowledge on the potential mirroring of 7TMR signaling between circulating blood leukocytes and the heart, and the related future possibilities in the management of HF patients.