The SGLT-2 inhibitor empagliflozin improves myocardial strain, reduces cardiac fibrosis and pro-inflammatory cytokines in non-diabetic mice treated with doxorubicin.

BACKGROUND: Empagliflozin (EMPA), a selective inhibitor of the sodium glucose co-transporter 2, reduced the risk of hospitalization for heart failure and cardiovascular death in type 2 diabetic patients in the EMPA-REG OUTCOME trial. Recent trials evidenced several cardio-renal benefits of EMPA in non-diabetic patients through the involvement of biochemical pathways that are still to be deeply analysed. We aimed to evaluate the effects of EMPA on myocardial strain of non-diabetic mice treated with doxorubicin (DOXO) through the analysis of NLRP3 inflammasome and MyD88-related pathways resulting in anti-apoptotic and anti-fibrotic effects. METHODS: Preliminary cellular studies were performed on mouse cardiomyocytes (HL-1 cell line) exposed to doxorubicin alone or combined to EMPA. The following analysis were performed: determination of cell viability (through a modified MTT assay), study of intracellular ROS production, lipid peroxidation (quantifying intracellular malondialdehyde and 4-hydroxynonenal), intracellular Ca2+ homeostasis. Moreover, pro-inflammatory studies were also performed: expression of NLRP3 inflammasome, MyD88 myddosome and p65/NF-κB associated to secretion of cytokines involved in cardiotoxicity (Interleukins 1ß, 8, 6). C57Bl/6 mice were untreated (Sham, n = 6) or treated for 10 days with doxorubicin (DOXO, n = 6), EMPA (EMPA, n = 6) or doxorubicin combined to EMPA (DOXO-EMPA, n = 6). DOXO was injected intraperitoneally. Ferroptosis and xanthine oxidase were studied before and after treatments. Cardiac function studies, including EF, FS and radial/longitudinal strain were analysed through transthoracic echocardiography (Vevo 2100). Cardiac fibrosis and apoptosis were histologically studied through Picrosirius red and TUNEL assay, respectively and quantified through pro-collagen-1α1, MMP-9 and Caspase-3 expression. Tissue NLRP3, MyD88 and cytokines were also quantified before and after treatments through ELISA methods. RESULTS: Cardiomyocytes exposed to doxorubicin increased the intracellular Ca2+ content and expression of several pro-inflammatory markers associated to cell death; co-incubation with EMPA reduced significantly the magnitude of the effects. In preclinical study, EMPA increased EF and FS compared to DOXO groups (p < 0.05), prevented the reduction of radial and longitudinal strain after 10 days of treatment with doxorubicin (RS) 30.3% in EMPA-DOXO vs 15.7% in DOXO mice; LS - 17% in EMPA-DOXO vs - 11.7% in DOXO mice (p < 0.001 for both). Significant reductions in ferroptosis, xanthine oxidase expression, cardiac fibrosis and apoptosis in EMPA associated to DOXO were also seen. A reduced expression of pro-inflammatory cytokines, NLRP3, MyD88 and NF-kB in heart, liver and kidneys was also seen in DOXO-EMPA group compared to DOXO (p < 0.001). CONCLUSION: EMPA reduced ferroptosis, fibrosis, apoptosis and inflammation in doxorubicin-treated mice through the involvement of NLRP3 and MyD88-related pathways, resulting in significant improvements in cardiac functions. These findings provides the proof of concept for translational studies designed to reduce adverse cardiovascular outcomes in non-diabetic cancer patients treated with doxorubicin.

Myocardial expression of somatotropic axis, adrenergic signalling, and calcium handling genes in heart failure with preserved ejection fraction and heart failure with reduced ejection fraction.

AIMS: Limited data are available regarding cardiac expression of molecules involved in heart failure (HF) pathophysiology. The majority of the studies have focused on end-stage HF with reduced ejection fraction (HFrEF) without comparison with healthy subjects, while no data are available with regard to HF with preserved ejection fraction (HFpEF). HFpEF is a condition whose multiple pathophysiological mechanisms are still not fully defined, with many proposed hypotheses remaining speculative due to limited access to human heart tissue. This study aimed at evaluating cardiac expression levels of key genes of interest in human biopsy samples from patients affected with HFrEF and HFpEF in order to possibly point out distinct phenotypes. METHODS AND RESULTS: Total RNA was extracted from left ventricular cardiac biopsies collected from stable patients with HFrEF (n = 6) and HFpEF (n = 7) and healthy subjects (n = 9) undergoing elective cardiac surgery for valvular replacement, mitral valvuloplasty, aortic surgery, or coronary artery bypass. Real-time PCR was performed to evaluate the mRNA expression levels of genes involved in somatotropic axis regulation [IGF-1, IGF-1 receptor (IGF-1R), and GH receptor (GHR)], in adrenergic signalling (GRK2, GRK5, ADRB1, and ADRB2), in myocardial calcium handling (SERCA2), and in TNF-α. Patients with HFrEF and HFpEF showed reduced serum IGF-1 circulating levels when compared with controls (102 ± 35.6, 138 ± 11.5, and 160 ± 13.2 ng/mL, P < 0.001, respectively). At myocardial level, HFrEF showed significant decreased GHR and increased IGF-1R expressions when compared with HFpEF and controls (0.54 ± 0.27, 0.94 ± 0.25, and 0.84 ± 0.2, P < 0.05 and 1.52 ± 0.9, 1.06 ± 0.21, and 0.72 ± 0.12, P < 0.05, respectively), while no differences in the local expression of IGF-1 mRNA were detected among the groups (0.80 ± 0.45, 0.97 ± 0.18, and 0.63 ± 0.23, P = 0.09, respectively). With regard to calcium handling and adrenergic signalling, HFrEF displayed significant decreased levels of SERCA2 (0.19 ± 0.39, 0.82 ± 0.15, and 0.87 ± 0.32, P < 0.01) and increased levels of GRK2 (3.45 ± 2.94, 0.93 ± 0.12, and 0.80 ± 0.14, P < 0.01) and GRK5 (1.32 ± 0.70, 0.71 ± 0.14, and 0.77 ± 0.15, P < 0.05), while no significant difference was found in ADRB1 (0.66 ± 0.4, 0.83 ± 0.3, and 0.86 ± 0.4) and ADRB2 mRNA expression (0.65 ± 0.3, 0.66 ± 0.2, and 0.68 ± 0.1) when compared with HFpEF and controls. Finally, no changes in the local expression of TNF-α were detected among groups. CONCLUSIONS: Heart failure with reduced ejection fraction and HFpEF patients with stable clinical condition display a distinct molecular milieu of genes involved in somatotropic axis regulation, calcium handling, and adrenergic derangement at a myocardial level. The unique opportunity to compare these results with a control group, as reference population, may contribute to better understand HF pathophysiology and to identify novel potential therapeutic targets that could be modulated to improve ventricular function in patients with HF.

Pharmacological inhibition of GRK2 improves cardiac metabolism and function in experimental heart failure.

AIMS: The effects of GRK2 inhibition on myocardial metabolism in heart failure (HF) are unchartered. In this work, we evaluated the impact of pharmacological inhibition of GRK2 by a cyclic peptide, C7, on metabolic, biochemical, and functional phenotypes in experimental HF. METHODS AND RESULTS: C7 was initially tested on adult mice ventricular myocyte from wild type and GRK2 myocardial deficient mice (GRK2-cKO), to assess the selectivity on GRK2 inhibition. Then, chronic infusion of 2 mg/kg/day of C7 was performed in HF mice with cryogenic myocardial infarction. Cardiac function in vivo was assessed by echocardiography and cardiac catheterization. Histological, biochemical, and metabolic studies were performed on heart samples at time points. C7 induces a significant increase of contractility in wild type but not in adult ventricle myocytes from GRK2-cKO mice, thus confirming C7 selectivity for GRK2. In HF mice, 4 weeks of treatment with C7 improved metabolic features, including mitochondrial organization and function, and restored the biochemical and contractile responses. CONCLUSIONS: GRK2 is a critical molecule in the physiological regulation of cardiac metabolism. Its alterations in the failing heart can be pharmacologically targeted, leading to the correction of metabolic and functional abnormalities observed in HF.

Inhibition of p110δ PI3K prevents inflammatory response and restenosis after artery injury.

Inflammatory cells play key roles in restenosis upon vascular surgical procedures such as bypass grafts, angioplasty and stent deployment but the molecular mechanisms by which these cells affect restenosis remain unclear. The p110δ isoform of phosphoinositide 3-kinase (PI3K) is mainly expressed in white blood cells. Here, we have investigated whether p110δ PI3K is involved in the pathogenesis of restenosis in a mouse model of carotid injury, which mimics the damage following arterial grafts. We used mice in which p110δ kinase activity has been disabled by a knockin (KI) point mutation in its ATP-binding site (p110δD910A/D910A PI3K mice). Wild-type (WT) and p110δD910A/D910A mice were subjected to longitudinal carotid injury. At 14 and 30 days after carotid injury, mice with inactive p110δ showed strongly decreased infiltration of inflammatory cells (including T lymphocytes and macrophages) and vascular smooth muscle cells (VSMCs), compared with WT mice. Likewise, PI-3065, a p110δ-selective PI3K inhibitor, almost completely prevented restenosis after artery injury. Our data showed that p110δ PI3K plays a main role in promoting neointimal thickening and inflammatory processes during vascular stenosis, with its inhibition providing significant reduction in restenosis following carotid injury. p110δ-selective inhibitors, recently approved for the treatment of human B-cell malignancies, therefore, present a new therapeutic opportunity to prevent the restenosis upon artery injury.

Antineoplastic-related cardiotoxicity, morphofunctional aspects in a murine model: contribution of the new tool 2D-speckle tracking.

OBJECTIVE: Considering that global left ventricular systolic radial strain is a sensitive technique for the early detection of left ventricular dysfunction due to antineoplastics and the analysis of segmental myocardial contractility, we evaluated this technique for early detection of trastuzumab-related cardiotoxicity by comparing it with cardiac structural damage. METHODS: Groups of six mice were injected with trastuzumab or doxorubicin, used either as single agents or in combination. Cardiac function was evaluated by transthoracic echocardiography measurements before and after treatment for 2 or 7 days, by using a Vevo 2100 high-resolution imaging system. After echocardiography, mice were euthanized, and hearts were processed for histological evaluations, such as cardiac fibrosis, apoptosis, capillary density, and inflammatory response. RESULTS: Trastuzumab-related cardiotoxicity was detected early by 2D strain imaging. Radial strain was reduced after 2 days in mice treated with trastuzumab alone (21.2%±8.0% vs 40.5%±4.8% sham; P<0.01). Similarly, trastuzumab was found to induce apoptosis, capillary density reduction, and inflammatory response in cardiac tissue after 2 days of treatment, in a fashion similar to doxorubicin. On the contrary, fractional shortening reduction and cardiac fibrosis were observed only after 7 days of trastuzumab treatment, in contrast to doxorubicin treatment which induced early fibrosis and fractional shortening reduction. CONCLUSION: The reduction of left ventricular systolic strain after 2 days of trastuzumab treatment may indicate early myocardial functional damage before the reduction in left ventricular ejection fraction and this early dysfunction is well correlated with structural myocardial damage, such as apoptosis and inflammatory response. Fractional shortening reduction after 7 days of trastuzumab treatment is related to fibrosis in cardiac tissue.

Strain Analysis in the Assessment of a Mouse Model of Cardiotoxicity due to Chemotherapy: Sample for Preclinical Research.

BACKGROUND: In recent years, the development of more effective anticancer drugs has provided great benefits in patients' quality of life by improving both prognosis and disease-free survival. Nevertheless, the frequency and severity of side-effects, with particular reference to cardiac toxicity, have gained particular attention. The purpose of this study was to create a precise and sensitive preclinical model, able to identify early contractile dysfunction in mice treated with chemotherapy, through use of speckle-tracking echocardiography. MATERIALS AND METHODS: We generated a mouse model of cardiotoxicity induced by doxorubicin. C57BL 6 mice were divided into two groups, treated for 7 days by intraperitoneal injections of placebo (vehicle) or doxorubicin (2.17 mg/kg), in order to characterize the cardiac phenotype in vivo. RESULTS: We demonstrated that doxorubicin caused ealy remodeling of the left ventricle: after two days of therapy, the radial, circumferential and strain rates were reduced respectively by 35%, 34%, and 39% (p-value ≤0.001). Moreover, histological analysis revealed that doxorubicin treatment increased fibrosis, cardiomyocyte diameter and apoptosis. CONCLUSION: In a murine model of doxorubicin-induced cardiac injury, we detected left ventricular dysfunction followed by alterations in conventional echocardiographic indices. Our study suggests that a change in strain could be an effective early marker of myocardial dysfunction for new anticancer treatments and, in preclinical studies, it might also be a valuable indicator for the assessment of activity of cardioprotective agents.

Doxorubicin impairs the insulin-like growth factor-1 system and causes insulin-like growth factor-1 resistance in cardiomyocytes.

BACKGROUND: Insulin-like growth factor-1 (IGF-1) promotes the survival of cardiomyocytes by activating type 1 IGF receptor (IGF-1R). Within the myocardium, IGF-1 action is modulated by IGF binding protein-3 (IGFBP-3), which sequesters IGF-1 away from IGF-1R. Since cardiomyocyte apoptosis is implicated in anthracycline cardiotoxicity, we investigated the effects of the anthracycline, doxorubicin, on the IGF-1 system in H9c2 cardiomyocytes. METHODS AND RESULTS: Besides inducing apoptosis, concentrations of doxorubicin comparable to those observed in patients after bolus infusion (0.1-1 µM) caused a progressive decrease in IGF-1R and increase in IGFBP-3 expression. Exogenous IGF-1 was capable to rescue cardiomyocytes from apoptosis triggered by 0.1 and 0.5 µM, but not 1 µM doxorubicin. The loss of response to IGF-1 was paralleled by a significant reduction in IGF-1 availability and signaling, as assessed by free hormone levels in conditioned media and Akt phosphorylation in cell lysates, respectively. Doxorubicin also dose-dependently induced p53, which is known to repress the transcription of IGF1R and induce that of IGFBP3. Pre-treatment with the p53 inhibitor, pifithrin-α, prevented apoptosis and the changes in IGF-1R and IGFBP-3 elicited by doxorubicin. The decrease in IGF-1R and increase in IGFBP-3, as well as apoptosis, were also antagonized by pre-treatment with the antioxidant agents, N-acetylcysteine, dexrazoxane, and carvedilol. CONCLUSIONS: Doxorubicin down-regulates IGF-1R and up-regulates IGFBP-3 via p53 and oxidative stress in H9c2 cells. This leads to resistance to IGF-1 that may contribute to doxorubicin-initiated apoptosis. Further studies are needed to confirm these findings in human cardiomyocytes and explore the possibility of manipulating the IGF-1 axis to protect against anthracycline cardiotoxicity.

Ranolazine protects from doxorubicin-induced oxidative stress and cardiac dysfunction.

AIMS: Doxorubicin is widely used against cancer; however, it can produce heart failure (HF). Among other hallmarks, oxidative stress is a major contributor to HF pathophysiology. The late INa inhibitor ranolazine has proven effective in treating experimental HF. Since elevated [Na+]i is present in failing myocytes, and has been recently linked with reactive oxygen species (ROS) production, our aim was to assess whether ranolazine prevents doxorubicin-induced cardiotoxicity, and whether blunted oxidative stress is a mechanism accounting for such protection. METHODS AND RESULT: In C57BL6 mice, doxorubicin treatment for 7 days produced LV dilation and decreased echo-measured fractional shortening (FS). Ranolazine (305 mg/kg/day) prevented LV dilation and dysfunction when co-administered with doxorubicin. Doxorubicin-induced cardiotoxicity was accompanied instead by elevations in atrial natriuretic peptide (ANP), BNP, connective tissue growth factor (CTGF), and matrix metalloproteinase 2 (MMP2) mRNAs, which were not elevated on co-treatment with ranolazine. Alterations in extracellular matrix remodelling were confirmed by an increase in interstitial collagen, which did not rise in ranolazine-co-treated hearts. Levels of poly(ADP-ribose) polymerase (PARP) and pro-caspase-3 measured by western blotting were lowered with doxorubicin, with increased cleavage of caspase-3, indicating activation of the proapoptotic machinery. Again, ranolazine prevented this activation. Furthermore, in HL-1 cardiomyocytes transfected with HyPer to monitor H2O2 emission, besides reducing the extent of cell death, ranolazine prevented the occurrence of oxidative stress caused by doxorubicin. Interestingly, similar protective results were obtained with the Na+/Ca2+ exchanger (NCX) inhibitor KB-R7943. CONCLUSIONS: Ranolazine protects against experimental doxorubicin cardiotoxicity. Such protection is accompanied by a reduction in oxidative stress, suggesting that INa modulates cardiac redox balance, resulting in functional and morphological derangements.

Endothelial G protein-coupled receptor kinase 2 regulates vascular homeostasis through the control of free radical oxygen species.

OBJECTIVE: The role of endothelial G protein-coupled receptor kinase 2 (GRK2) was investigated in mice with selective deletion of the kinase in the endothelium (Tie2-CRE/GRK2(fl/fl)). APPROACH AND RESULTS: Aortas from Tie2-CRE/GRK2(fl/fl) presented functional and structural alterations as compared with control GRK2(fl/fl) mice. In particular, vasoconstriction was blunted to different agonists, and collagen and elastic rearrangement and macrophage infiltration were observed. In primary cultured endothelial cells deficient for GRK2, mitochondrial reactive oxygen species was increased, leading to expression of cytokines. Chronic treatment with a reactive oxygen species scavenger in mice corrected the vascular phenotype by recovering vasoconstriction, structural abnormalities, and reducing macrophage infiltration. CONCLUSIONS: These results demonstrate that GRK2 removal compromises vascular phenotype and integrity by increasing endothelial reactive oxygen species production.

SOCS1 gene transfer accelerates the transition to heart failure through the inhibition of the gp130/JAK/STAT pathway.

AIMS: The suppressors of cytokine signalling (SOCS) are identified inhibitors of cytokine and growth factor signalling that act via the Janus kinase (JAK) signal transducers and activators of transcription (STAT) pathways. Aberrant JAK/STAT signalling promotes progression from hypertrophy to heart failure. Little information is available concerning the role of SOCS in the transition from hypertrophy to heart failure. To this aim, we investigated the effects of SOCS1 overexpression obtained by in vivo adeno-associated gene transfer using an aortopulmonary cross-clamping technique in a chronic pressure-overload cardiac rat model. METHODS AND RESULTS: Rats were randomized into four groups: sham-operated (n = 18), aortic banding (AB) (n = 18), AB + viral vector encoding for haemoagglutinin (AB + HA, n = 16), and AB + viral vector encoding for SOCS1 (AB + SOCS1, n = 18). Echocardiographic and haemodynamic measurements were performed 15 weeks after banding. While SOCS3 was upregulated during the hypertrophic phase, SOCS1 transcript levels increased significantly between 15 and 20 weeks. Remodelling was markedly worse in AB + SOCS1, showed larger left ventricular internal dimensions (+16%), higher end-diastolic pressures (+57%) and wall stress (+45%), and reduced fractional shortening (-32%) compared with AB + HA; apoptotic rate was increased three-fold and the gp130 pathway was inhibited. Ex vivo experiments showed that mechanical stretch upregulated SOCS1 expression, which was in turn attenuated by tumour necrosis factor-α (TNF-α) inhibition. CONCLUSION: Enhanced SOCS1 myocardial signalling is associated with accelerated transition from hypertrophy to failure in an established model of pressure overload. SOCS1 may represent an attractive target for the prevention of heart failure progression.

Metformin prevents the development of chronic heart failure in the SHHF rat model.

Insulin resistance is a recently identified mechanism involved in the pathophysiology of chronic heart failure (CHF). We investigated the effects of two insulin-sensitizing drugs (metformin and rosiglitazone) in a genetic model of spontaneously hypertensive, insulin-resistant rats (SHHF). Thirty SHHF rats were randomized into three treatment groups as follows: 1) metformin (100 mg/kg per day), 2) rosiglitazone (2 mg/kg per day), and 3) no drug. Ten Sprague-Dawley rats served as normal controls. At the end of the treatment period (12 months), the cardiac phenotype was characterized by histology, echocardiography, and isolated perfused heart studies. Metformin attenuated left ventricular (LV) remodeling, as shown by reduced LV volumes, wall stress, perivascular fibrosis, and cardiac lipid accumulation. Metformin improved both systolic and diastolic indices as well as myocardial mechanical efficiency, as shown by improved ability to convert metabolic energy into mechanical work. Metformin induced a marked activation of AMP-activated protein kinase, endothelial nitric oxide synthase, and vascular endothelial growth factor and reduced tumor necrosis factor-α expression and myocyte apoptosis. Rosiglitazone did not affect LV remodeling, increased perivascular fibrosis, and promoted further cardiac lipid accumulation. In conclusion, long-term treatment with metformin, but not with rosiglitazone, prevents the development of severe CHF in the SHHF model by a wide-spectrum interaction that involves molecular, structural, functional, and metabolic-energetic mechanisms.

Comparison of preclinical cardiotoxic effects of different ErbB2 inhibitors.

Two novel human antitumor immunoconjugates, made up of a human anti-ErbB2 scFv, Erbicin, fused with either a human RNase or the Fc region of a human IgG1, are selectively cytotoxic for ErbB2-positive cancer cells in vitro and in vivo. The Erbicin-derived immunoagents (EDIA) target an epitope different from that of trastuzumab, the only humanized antibody currently prescribed for treatment of ErbB2-positive breast cancer (BC). As Trastuzumab has shown cardiotoxic effects, in this study, we evaluated if any side effects were exerted also by EDIA, used as single agents or in combination with anthracyclines. Furthermore, we compared the in vitro and in vivo cardiotoxic effects of EDIA with those of the other available anti-ErbB2 drugs: Trastuzumab, 2C4 (Pertuzumab), and Lapatinib. In this article, we show that EDIA, in contrast with Trastuzumab, 2C4, and Lapatinib, have no toxic effects on human fetal cardiomyocytes in vitro, and do not induce additive toxicity when combined with doxorubicin. Furthermore, EDIA do not impair cardiac function in vivo in mice, as evaluated by Color Doppler echocardiography, whereas Trastuzumab significantly reduces radial strain (RS) at day 2 and fractional shortening (FS) at day 7 of treatment in a fashion similar to doxorubicin. Also 2C4 and Lapatinib significantly reduce RS after only 2 days of treatment, even though they showed cardiotoxic effects less pronounced than those of Trastuzumab. These results strongly indicate that RS could become a reliable marker to detect early cardiac dysfunction and that EDIA could fulfill the therapeutic need of patients ineligible to Trastuzumab treatment because of cardiac dysfunction.

Recombinant human FSH reduces sperm DNA fragmentation in men with idiopathic oligoasthenoteratozoospermia.

A prospective randomized controlled study was designed to evaluate the effects of recombinant human follicle-stimulating hormone (rFSH) treatment on sperm DNA fragmentation in men with idiopathic oligoasthenoteratozoospermia (iOAT). One hundred twenty-nine men with sperm count less than 10 × 10(6) spermatozoa/mL and forward motility <25% were included; normal serum levels of FSH, luteinizing hormone (LH), and testosterone, and no other causes of infertility were enrolled. The patients were randomized into 2 groups: 65 men were treated on alternate days for 90 days with injections of 150 IU rFSH, and 64 subjects received nonantioxidant vitamin supplements. Main outcome measures were serum levels of FSH, LH, testosterone, and inhibin B and DNA fragmentation index (DFI) at baseline and after 90 days. No significant differences were observed between the 2 groups with regard to sperm parameters and hormone values. The DFI was similar between the 2 groups at the time of the enrollment but reduced significantly (P < .05) after rFSH therapy in study group, whereas no significant variation occurred in the control group. In the subgroup of patients with high basal DFI values (>15%), rFSH treatment significantly increased DFI (P < .01), whereas no significant variation occurred after 90 days of vitamin supplements. We conclude that rFSH administration improves sperm DNA integrity in iOAT men with increased DFI values. The degree of sperm DFI might be useful to identify those iOAT patients in which rFSH treatment can be advantageous.

Complementary therapeutic effects of dual delivery of insulin-like growth factor-1 and vascular endothelial growth factor by gelatin microspheres in experimental heart failure.

AIMS: Strategies to prevent adverse left ventricular (LV) remodelling after myocardial infarction have included several traditional approaches and novel cell-based or gene therapies. Delivery of growth factors in post-infarction heart failure has emerged as a valuable alternative strategy. Our aim was to investigate the effects of sequential release of vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1) from biodegradable gelatin microspheres in experimental heart failure. METHODS AND RESULTS: Gelatin hydrogel microspheres were known to guarantee a sustained release of encapsulated growth factors, characterized by an initial burst followed by a slower release. Rats with moderate myocardial infarction were randomized to receive empty microspheres (MI), microspheres loaded with IGF-1 or VEGF, or a combination thereof (DUAL). Myocardial injections of microspheres were performed at the time of surgery, and treatment lasted 4 weeks. Echocardiography, LV catheterization, morphometric histology and immunohistochemistry, and molecular assessment of downstream mediators [e.g. Akt, endothelial nitric oxide synthase (eNOS), and sarco/endoplasmic reticulum calcium ATPase-2 (SERCA-2)] were assessed at the end of the treatment period. Infarct sizes were 33 ± 2, 28 ± 4, 24 ± 3, and 16 ± 3% in the MI, IGF-1, VEGF, and DUAL groups, respectively. IGF-1 attenuated LV remodelling, improved LV systolic and diastolic function, increased myocyte size, and reduced apoptotic deaths, capillary loss, and indexes of inflammation. VEGF-treated animals displayed a marked myocardial neoangiogenesis that led to the formation of mature vessels if combined with IGF-1 delivery. Downstream effects of IGF-1 were principally mediated by the Akt-mTOR (mammalian target of rapamycin)-dependent pathway, and both growth factors, particularly VEGF, induced a robust and sustained increase of eNOS. CONCLUSION: IGF-1 and VEGF exerted complementary therapeutic effects in post-infarction heart failure. Biodegradable gelatin microspheres provide sustained and controlled growth factor release locally, exposing myocardial tissue without the side effects of systemic administration.

Cross-talk between PKA and Akt protects endothelial cells from apoptosis in the late ischemic preconditioning.

OBJECTIVE: The aim of this study was to explore the molecular mechanisms involved in late preconditioning-induced cell protection in endothelial cells. METHODS AND RESULTS: Preconditioning (PC) was induced by exposing bovine aortic endothelial cells (BAECs) to 3 cycles of 15 minutes of hypoxia followed by 15 minutes of reoxygenation. A 12-hour period of hypoxia induced cell death in 60% of BAECs (48+/-5% apoptosis, 12+/-4% necrosis). Early and late PC decreased hypoxia-induced apoptotic (25+/-5% and 28+/-4%, respectively) and necrotic (6+/-3%, and 8+/-2%, respectively) cell death. Consistently, hypoxia-induced caspase-3 cleavage was reduced by PC. Pretreatment with H89 (protein kinase A [PKA] inhibitor), LY294002 (phosphatidyl-inositol-3-kinase [PI3K] inhibitor), and N-acetyl-cysteine (antioxidant) abrogated late PC-induced cell protection, whereas inhibition of protein kinase C by Go6983, and of nitric oxide synthesis by L-NAME,1400W and bovine eNOS siRNA did not. In addition, in early and late PC, PKA physically interacted with the phosphorylated form of Akt, suggesting that PKA is required for Akt phosphorylation. Expression of PKA and Akt dominant negative mutants inhibited ischemic late PC-induced protection, indicating that these kinases play a key role in late PC-mediated cell protection. CONCLUSIONS: Late ischemic PC protects BAECs against hypoxia through PKA- and PI3K-dependent activation of Akt.

Insulin resistance affects the cytoprotective effect of insulin in cardiomyocytes through an impairment of MAPK phosphatase-1 expression.

OBJECTIVE: Insulin protects cardiomyocytes from apoptosis. Insulin resistance usually refers to a defect in the ability of insulin to stimulate glucose uptake. It is unknown, however, whether or not insulin resistance compromises the cell-protective effect of the hormone. Caspases are a family of cysteine proteases that regulate apoptosis. We explored the effects of insulin resistance on hypoxia-induced caspase-3 activation in cardiomyocytes. METHODS: Experiments were performed in cultured neonatal rat cardiomyocytes. Insulin resistance was induced by treating cardiac myocytes with isoproterenol, a beta-adrenergic receptor agonist. RESULTS: Twelve hours of hypoxia-induced caspase-3 cleavage, which was inhibited by treatment with insulin, while pre-treatment with isoproterenol abolished the insulin effect. Hypoxia-induced cleavage of caspase-3 was mediated by p38 mitogen-activated protein kinase (MAPK). Insulin inhibited hypoxia-induced phosphorylation of p38 through MAPK phosphatase-1 (MKP-1). Insulin-induced MKP-1 expression was mediated by extracellular signal-regulated protein kinases (ERK) 1/2, c-Jun NH2-terminal kinases (JNK) MAPK, and phosphatidylinositol 3-kinase (PI3K)/Akt pathways. Isoproterenol stimulation failed to induce expression of MKP-1; moreover, insulin resistance induced by long-term beta-adrenergic stimulation inhibited insulin-evoked expression of MKP-1 by impairing insulin-induced phosphorylation of both ERK1/2 and JNK without affecting Akt kinase activity. Furthermore, concomitant activation of Akt, ERK 1/2, and JNK was required for insulin to exert its protective effect against the hypoxia-induced cleavage of caspase-3. CONCLUSIONS: The results of this study lead to the conclusions that, in cardiac myocytes, antiapoptotic signals induced by insulin are mediated by more than one signaling pathway, and that long-term beta-adrenergic receptor stimulation impairing some of these pathways affects the cytoprotective action of insulin.

Effects of biventricular pacing on interstitial remodelling, tumor necrosis factor-alpha expression, and apoptotic death in failing human myocardium.

AIMS: Recent data from the COMPANION trial have documented that cardiac resynchronization therapy (CRT) with biventricular (BiV) pacing reduces mortality and hospitalization in patients with advanced CHF, but little is known regarding the cellular and molecular mechanisms of CRT. Our aim is to evaluate interstitial remodelling, tumor necrosis factor-alpha (TNF-alpha) expression, and apoptosis in patients with advanced CHF treated with CRT. METHODS AND RESULTS: We performed endomyocardial biopsies in 10 patients, aged 62, with dilated cardiomyopathy before and 6 months after the implantation of a BiV pacing device. Clinical status and left ventricular (LV) architecture and function were assessed as well as myocardial histology, TNF-alpha expression, and apoptotic index. CRT improved clinical status, as shown by a significant reduction of the Minnesota living with heart failure questionnaire (MLHFQ) score (from 53 to 40) and 6-min walked distance (from 290 to 330 m) (all P<0.05 vs. baseline). This was associated with reverse LV remodelling substantiated by significant reductions of LV volumes and end-systolic circumferential wall stress. Examination of myocardial tissue revealed a significant decrease of collagen volume fraction (CVF) (from 25.16 to 18.0%), TNF-alpha expression (from 9.5 to 3.6 pixel x 10(3)), and apoptotic index (from 2030 to 1408 apoptotic nuclei/10(6)), with increased capillary density (from 1801 to 2011 capillary/mm(2)) after 6 months of CRT (all P<0.05 vs. baseline). Moreover, changes in TNF-alpha expression were positively correlated with both CVF and end-systolic circumferential wall stress (r=0.80 and 0.70, respectively). CONCLUSION: We provide the first evidence that CRT reduces interstitial remodelling, TNF-alpha expression, and apoptosis. The data may explain the beneficial effects of CRT on CHF progression and survival.

[The role of aldosterone in the development of postinfarction fibrosis]. / II ruolo dell'aldosterone nello sviluppo della fibrosi postinfartuale.

Aldosterone was discovered in 1953, and until the beginning of the 1960s, when spironolactone was developed, it was the focus of considerable interest among the scientific community. The following 30 years represented a sort of Dark Age, interrupted by the Weber's classic studies. He first demonstrated the pivotal role of aldosterone in the promotion of cardiac hypertrophy and fibrosis and such an observation represented a solid background for the implementation of large survival trials, the RALES and the EPHESUS. These landmark studies showed that aldosterone receptor blockade prolongs survival in advanced and postinfarction heart failure, respectively. After a myocardial infarction, there is a significant upregulation of the local steroidogenic system in the area remote from the scar, that leads to a remarkable fibroblast activation, collagen deposition, and reactive fibrosis. Fibrosis in turn further impairs systolic and diastolic function, and induces electrical heterogeneity with attendant ominous arrhythmias. The following review will dwell upon the importance of fibrosis in postinfarction heart failure, the role of aldosterone, and the novel therapeutic approach based on mineralocorticoid receptor blockade.

Aldosterone receptor blockade improves left ventricular remodeling and increases ventricular fibrillation threshold in experimental heart failure.

OBJECTIVES: To investigate the effects of aldosterone receptor blockade in postinfarction heart failure. METHODS: Eighty-seven rats with moderate myocardial infarction were randomized to receive either no drug or canrenone, the active metabolite of spironolactone, 20 mg/kg/day, or ramipril, 1 mg/kg/day, or a combination of the two drugs. Treatment was initiated 1 month after coronary ligation and lasted 4 weeks. Echocardiography was performed at baseline and after 4 weeks. LV catheterization, isolated heart studies, morphometric histology, myocardial norepinephrine and SERCA-2 mRNA were assessed at the end of the treatment period. RESULTS: Infarct sizes were 33+/-3, 32+/-3, 34+/-3, and 34+/-4% in the placebo, canrenone, ramipril, and combination groups, respectively. Canrenone attenuated LV remodeling, improved LV systolic and diastolic function, and markedly reduced interstitial and perivascular fibrosis. These effects were increased by concomitant ramipril therapy. Moreover, myocardial norepinephrine content was decreased while ventricular fibrillation threshold significantly augmented by canrenone. SERCA-2 levels remained unchanged. CONCLUSIONS: Canrenone attenuated LV dilation and interstitial remodeling, and improved LV filling dynamics and systolic function in the rat model of postinfarction heart failure. Addition of ramipril conferred further cardioprotection. Canrenone also reduced myocardial norepinephrine content and increased ventricular fibrillation threshold. The data provide a potential explanation for the decreased sudden death observed in the RALES study. The mechanisms of action of aldosterone inhibition are still poorly understood, despite its proven efficacy in heart failure. Rats with postinfarction heart failure were randomized to receive for 1 month either no drug or canrenone, or ramipril, or a combination of canrenone and ramipril. Canrenone treatment was associated with a significant attenuation of LV dilation, better LV diastolic and systolic dynamics, and a marked reduction of reactive fibrosis. These effects were enhanced by concomitant ramipril therapy. Moreover, canrenone increased ventricular fibrillation threshold and reduced myocardial norepinephrine content. The data may explain the reduced mortality demonstrated by the RALES.