RESUMEN
Background In adults with heart failure, elevated heart rate is associated with lower survival. We determined whether an elevated heart rate was associated with an increased risk of death or heart transplant in children with dilated cardiomyopathy. Methods and Results The study is an analysis of the Pediatric Cardiomyopathy Registry and includes baseline data, annual follow-up, and censoring events (transplant or death) in 557 children (51% male, median age 1.8 years) with dilated cardiomyopathy diagnosed between 1994 and 2011. An elevated heart rate was defined as 2 or more SDs above the mean heart rate of children, adjusted for age. The primary outcomes were heart transplant and death. Heart rate was elevated in 192 children (34%), who were older (median age, 2.3 versus 0.9 years; P<0.001), more likely to have heart failure symptoms (83% versus 67%; P<0.001), had worse ventricular function (median fractional shortening z score, -9.7 versus -9.1; P=0.02), and were more often receiving anticongestive therapies (96% versus 86%; P<0.001) than were children with a normal heart rate. Controlling for age, ventricular function, and cardiac medications, an elevated heart rate was independently associated with death (adjusted hazard ratio [HR] 2.6; P<0.001) and with death or transplant (adjusted HR 1.5; P=0.01). Conclusions In children with dilated cardiomyopathy, elevated heart rate was associated with an increased risk of death and cardiac transplant. Further study is warranted into the association of elevated heart rate and disease severity in children with dilated cardiomyopathy and as a potential target of therapy.
Asunto(s)
Cardiomiopatía Dilatada/mortalidad , Frecuencia Cardíaca , Cardiomiopatía Dilatada/fisiopatología , Niño , Preescolar , Femenino , Trasplante de Corazón/estadística & datos numéricos , Humanos , Lactante , Estimación de Kaplan-Meier , Masculino , Modelos de Riesgos Proporcionales , Sistema de Registros , Factores de RiesgoRESUMEN
H11 kinase/Hsp22 (Hsp22) is a small heat shock protein, which, when overexpressed cardiac specifically in transgenic (TG) mice, induces stable left ventricular (LV) hypertrophy. Hsp22 also increases oxidative phosphorylation and mitochondrial reactive oxygen species (ROS) production, mechanisms mediating LV hypertrophy, senescence and reduced lifespan. Therefore, we investigated whether ROS production mediates LV hypertrophy, senescence and reduced life span in Hsp22 TG mice. Survival curves revealed that TG mice had a 48% reduction in their mean life span compared to wild type (WT) mice. This was associated with a significant increase in senescence markers, such as p16, p19 mRNA levels as well as the percentage of ß-galactosidase positive cells and telomerase activity. Oxidized (GSSG)/reduced (GSH) glutathione ratio, an indicator of oxidative stress, and ROS production from 3 major cellular sources was measured in cardiac tissue. Hearts from TG mice exhibited a decrease in GSH/GSSG ratio together with increased ROS production from all sources. To study the role of ROS, mice were treated with the antioxidant Tempol from weaning to their sacrifice. Chronic Tempol treatment abolished oxidative stress and overproduction of ROS, and reduced myocardial hypertrophy and Akt phosphorylation in TG mice. Tempol also significantly extended life span and prevented aging markers in TG mice. Taken together these results show that overexpression of Hsp22 increases oxidative stress responsible for the induction of hypertrophy and senescence and ultimately reduction in life span.
Asunto(s)
Proteínas de Choque Térmico/metabolismo , Hipertrofia Ventricular Izquierda/metabolismo , Mitocondrias/metabolismo , Chaperonas Moleculares/metabolismo , Miocardio/patología , Animales , Antioxidantes/administración & dosificación , Células Cultivadas , Senescencia Celular , Óxidos N-Cíclicos/administración & dosificación , Proteínas de Choque Térmico/genética , Hipertrofia Ventricular Izquierda/genética , Longevidad , Masculino , Ratones , Ratones Transgénicos , Chaperonas Moleculares/genética , Miocardio/metabolismo , Estrés Oxidativo , Fosforilación , Proteínas Proto-Oncogénicas c-akt/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Marcadores de SpinRESUMEN
BACKGROUND: Elevated resting heart rate (HR) is a risk factor and therapeutic target in patients with heart failure (HF) and reduced ejection fraction (HFrEF). Previous studies indicate a genetic contribution to HR in population samples but there is little data in patients with HFrEF. METHODS: Patients who met Framingham criteria for HF and had an ejection fraction < 50% were prospectively enrolled in a genetic HF registry (2007-2015, n = 1060). All participants donated blood for DNA and underwent genome-wide genotyping with additional variants called via imputation. We performed testing of previously identified variant "hits" (43 loci) as well as a genome-wide association (GWAS) of HR, adjusted for race, using Efficient Mixed-Model Association Expedited (EMMAX). RESULTS: The cohort was 35% female, 51% African American, and averaged 68 years of age. There was a 2 beats per minute (bpm) difference in HR by race, AA being slightly higher. Among 43 candidate variants, 4 single nucleotide polymorphisms (SNPs) in one gene (GJA1) were significantly associated with HR. In genome-wide testing, one statistically significant association peak was identified on chromosome 22q13, with strongest SNP rs535263906 (p = 3.3 × 10-8). The peak is located within the gene Cadherin EGF LAG Seven-Pass G-Type Receptor 1 (CELSR1), encoding a cadherin super-family cell surface protein identified in GWAS of other phenotypes (e.g., stroke). The highest associated SNP was specific to the African American population. CONCLUSIONS: These data confirm GJA1 association with HR in the setting of HFrEF and identify novel candidate genes for HR in HFrEF patients, particularly CELSR1. These associations should be tested in additional cohorts.
Asunto(s)
Cadherinas/genética , Conexina 43/genética , Insuficiencia Cardíaca/genética , Frecuencia Cardíaca/genética , Negro o Afroamericano/genética , Anciano , Cromosomas Humanos Par 22/genética , Estudios de Cohortes , Femenino , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Insuficiencia Cardíaca/patología , Humanos , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple/genética , Factores de Riesgo , Volumen Sistólico/genéticaRESUMEN
INTRODUCTION: This review summarizes the current management of heart failure (HF) in patients with reduced ejection fraction and the potential role of heart rate lowering agents in select populations, as recommended in the updated guidelines. Areas covered: PubMed was searched for studies that evaluated the role of heart rate lowering or ivabradine in HF management. Expert commentary: Targeting heart rate may offer benefit when added to renin-angiotensin aldosterone antagonists, and beta-blockers. Ivabradine is a heart rate lowering agent that acts on the funny current (If) in the sinoatrial node, thereby reducing heart rate without directly affecting cardiac contraction and relaxation. Clinical data from a phase III trial demonstrated that ivabradine reduced the composite end point of cardiovascular death or hospital admission for worsening systolic HF, while maintaining an acceptable safety profile in patients receiving standard of care therapy. These data, in addition to more recently published guidelines, suggest ivabradine as a promising new treatment option for lowering heart rate after optimizing standard therapy in select patients with chronic HF.
Asunto(s)
Benzazepinas/uso terapéutico , Insuficiencia Cardíaca/tratamiento farmacológico , Frecuencia Cardíaca/efectos de los fármacos , Antagonistas Adrenérgicos beta/uso terapéutico , Fármacos Cardiovasculares/uso terapéutico , Enfermedad Crónica , Insuficiencia Cardíaca/fisiopatología , Insuficiencia Cardíaca Sistólica/tratamiento farmacológico , Hospitalización , Humanos , Ivabradina , Resultado del Tratamiento , Disfunción Ventricular Izquierda/tratamiento farmacológicoRESUMEN
OBJECTIVE: To determine the potential impact of erenumab, a human anti-calcitonin gene-related peptide (CGRP) receptor monoclonal antibody, on total exercise time (TET), time to exercise-induced angina, and ST depression in a double-blind, placebo-controlled study in patients with stable angina due to documented coronary artery disease. BACKGROUND: The relative importance of the CGRP receptor pathway during myocardial ischemia has not been established. METHODS: An exercise treadmill test was conducted following a single IV infusion of erenumab 140 mg or placebo. The primary endpoint was the change from baseline in exercise duration as measured by TET with a noninferiority margin of -90 seconds. Safety follow-up visits occurred through week 12. Eighty-eight participants were included in the analysis. RESULTS: LS mean (SE) change in TET was -2.9 [14.8] seconds in the erenumab group and 8.1 [14.4] seconds in placebo; adjusted mean (90% CI) treatment difference was -11.0 (-44.9, 22.9) seconds. The CI lower bound (-44.9 sec) did not reach pre-defined non-inferiority margin of -90 seconds, demonstrating that TET change from baseline in the erenumab group was non-inferior to placebo. There was no difference in time to exercise-induced angina in erenumab and placebo groups (median [90% CI] time of 500 [420, 540] vs 508 [405, 572] seconds; hazard ratio [90% CI]: 1.11 [0.73, 1.69], P = .69) or time to onset of ≥1 mm ST-segment depression (median [90% CI] time of 407 [380, 443] vs 420 [409,480] seconds; hazard ratio [95% CI]: 1.14 [0.76, 1.69], P = .59). Adverse events were reported by 27% and 32% of patients in erenumab and placebo groups. CONCLUSIONS: Erenumab did not adversely affect exercise time in a high cardiovascular risk population of patients, supporting that inhibition of the canonical CGRP receptor does not worsen myocardial ischemia.
Asunto(s)
Angina Estable/inducido químicamente , Angina Estable/fisiopatología , Anticuerpos Monoclonales Humanizados/efectos adversos , Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina/efectos adversos , Electrocardiografía/efectos de los fármacos , Prueba de Esfuerzo/efectos de los fármacos , Anciano , Anticuerpos Monoclonales Humanizados/administración & dosificación , Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina/administración & dosificación , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de TiempoRESUMEN
The valosin-containing protein (VCP) participates in signaling pathways essential for cell homeostasis in multiple tissues, however, its function in the heart in vivo remains unknown. Here we offer the first description of the expression, function and mechanism of action of VCP in the mammalian heart in vivo in both normal and stress conditions. By using a transgenic (TG) mouse with cardiac-specific overexpression (3.5-fold) of VCP, we demonstrate that VCP is a new and powerful mediator of cardiac protection against cell death in vivo, as evidenced by a 50% reduction of infarct size after ischemia/reperfusion versus wild type. We also identify a novel role of VCP in preserving mitochondrial respiration and in preventing the opening of mitochondrial permeability transition pore in cardiac myocytes under stress. In particular, by genetic deletion of inducible isoform of nitric oxide synthase (iNOS) from VCP TG mouse and by pharmacological inhibition of iNOS in isolated cardiac myocytes, we reveal that an increase of expression and activity of iNOS in cardiomyocytes by VCP is an essential mechanistic link of VCP-mediated preservation of mitochondrial function. These data together demonstrate that VCP may represent a novel therapeutic avenue for the prevention of myocardial ischemia.
Asunto(s)
Respiración de la Célula , Supervivencia Celular , Mitocondrias/metabolismo , Miocardio/metabolismo , Proteína que Contiene Valosina/metabolismo , Adenosina Difosfato/metabolismo , Animales , Biomarcadores , Respiración de la Célula/genética , Supervivencia Celular/genética , Femenino , Eliminación de Gen , Expresión Génica , Masculino , Ratones , Ratones Transgénicos , Mitocondrias/genética , Proteínas de Transporte de Membrana Mitocondrial/genética , Proteínas de Transporte de Membrana Mitocondrial/metabolismo , Poro de Transición de la Permeabilidad Mitocondrial , Modelos Biológicos , Daño por Reperfusión Miocárdica/genética , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Miocitos Cardíacos/metabolismo , Óxido Nítrico Sintasa de Tipo II/genética , Óxido Nítrico Sintasa de Tipo II/metabolismo , Consumo de Oxígeno , Proteína que Contiene Valosina/genéticaRESUMEN
The increasing burden and the continued suboptimal outcomes for patients with heart failure underlines the importance of continued research to develop novel therapeutics for this disorder. This can only be accomplished with successful translation of basic science discoveries into direct human application through effective clinical trial design and execution that results in a substantially improved clinical course and outcomes. In this respect, phase II clinical trials play a pivotal role in determining which of the multitude of potential basic science discoveries should move to the large and expansive registration trials in humans. A critical examination of the phase II trials in heart failure reveals multiple shortcomings in their concept, design, execution, and interpretation. To further a dialogue on the challenges and potential for improvement and the role of phase II trials in patients with heart failure, the Food and Drug Administration facilitated a meeting on October 17, 2016, represented by clinicians, researchers, industry members, and regulators. This document summarizes the discussion from this meeting and provides key recommendations for future directions.
Asunto(s)
Fármacos Cardiovasculares/uso terapéutico , Ensayos Clínicos Fase II como Asunto/normas , Insuficiencia Cardíaca/tratamiento farmacológico , Proyectos de Investigación/normas , Fármacos Cardiovasculares/efectos adversos , Ensayos Clínicos Fase II como Asunto/métodos , Consenso , Insuficiencia Cardíaca/diagnóstico , Insuficiencia Cardíaca/mortalidad , Insuficiencia Cardíaca/fisiopatología , Humanos , Resultado del Tratamiento , Estados Unidos , United States Food and Drug AdministrationRESUMEN
OBJECTIVES: In the Systolic Heart Failure Treatment with the If Inhibitor Ivabradine Trial (SHIFT), slowing of the heart rate with ivabradine reduced cardiovascular death or heart failure hospitalizations among patients with systolic chronic heart failure (CHF). Subsequently, in the Study Assessing the Morbidity-Mortality Benefits of the If Inhibitor Ivabradine in Patients with Coronary Artery Disease (SIGNIFY) slowing of the heart rate in patients without CHF provided no benefit for cardiovascular death or nonfatal myocardial infarction (primary composite end point), with secondary analyses suggesting possible harm in the angina subgroup. Therefore, we examined the impact of ivabradine in the patients with CHF plus angina in SHIFT. METHODS: SHIFT enrolled adults with stable, symptomatic CHF, a left ventricular ejection fraction ≤35% and a sinus rhythm with a resting heart rate ≥70 bpm. Outcomes were the SHIFT and SIGNIFY primary composite end points and their components. RESULTS: Of 6,505 patients in SHIFT, 2,220 (34%) reported angina at randomization. Ivabradine numerically, but not significantly, reduced the SIGNIFY primary composite end point by 8, 11 and 11% in the SHIFT angina subgroup, nonangina subgroup and overall population, respectively. Ivabradine also reduced the SHIFT primary composite end point in all 3 subgroups. CONCLUSIONS: In SHIFT, ivabradine showed consistent reduction of cardiovascular outcomes in patients with CHF; similar results were seen in the subgroup of SHIFT patients with angina.
Asunto(s)
Angina de Pecho/tratamiento farmacológico , Benzazepinas/uso terapéutico , Fármacos Cardiovasculares/uso terapéutico , Insuficiencia Cardíaca Sistólica/tratamiento farmacológico , Adulto , Anciano , Angina de Pecho/complicaciones , Femenino , Insuficiencia Cardíaca Sistólica/complicaciones , Insuficiencia Cardíaca Sistólica/fisiopatología , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Ivabradina , Masculino , Persona de Mediana Edad , Volumen SistólicoRESUMEN
The epidemiological, clinical, and societal implications of the heart failure (HF) epidemic cannot be overemphasized. Approximately half of all HF patients have HF with preserved ejection fraction (HFpEF). HFpEF is largely a syndrome of the elderly, and with aging of the population, the proportion of patients with HFpEF is expected to grow. Currently, there is no drug known to improve mortality or hospitalization risk for these patients. Besides mortality and hospitalization, it is imperative to realize that patients with HFpEF have significant impairment in their functional capacity and their quality of life on a daily basis, underscoring the need for these parameters to ideally be incorporated within a regulatory pathway for drug approval. Although attempts should continue to explore therapies to reduce the risk of mortality or hospitalization for these patients, efforts should also be directed to improve other patient-centric concerns, such as functional capacity and quality of life. To initiate a dialogue about the compelling need for and the challenges in developing such alternative endpoints for patients with HFpEF, the US Food and Drug Administration on November 12, 2015, facilitated a meeting represented by clinicians, academia, industry, and regulatory agencies. This document summarizes the discussion from this meeting.
Asunto(s)
Insuficiencia Cardíaca/terapia , Hospitalización , Mortalidad , Medición de Resultados Informados por el Paciente , Volumen Sistólico , Congresos como Asunto , Aprobación de Drogas , Descubrimiento de Drogas , Prueba de Esfuerzo , Insuficiencia Cardíaca/fisiopatología , Humanos , Evaluación de Resultado en la Atención de Salud , Consumo de Oxígeno , Calidad de Vida , Estados Unidos , United States Food and Drug Administration , Prueba de PasoRESUMEN
OBJECTIVES: Stress-inducible heat shock protein 22 (Hsp22) confers protection against ischemia through induction of the inducible isoform of nitric oxide synthase (iNOS). Hsp22 overexpression in vivo stimulates cardiac mitochondrial respiration, whereas Hsp22 deletion in vivo significantly reduces respiration. We hypothesized that Hsp22-mediated regulation of mitochondrial function is dependent upon its mitochondrial translocation together with iNOS. METHODS AND RESULTS: Adenoviruses harboring either the full coding sequence of Hsp22 (Ad-WT-Hsp22) or a mutant lacking a N-terminal 20 amino acid putative mitochondrial localization sequence (Ad-N20-Hsp22) were generated, and infected in rat neonatal cardiomyocytes. Compared to ß-Gal control, WT-Hsp22 accumulated in mitochondria by 2.5 fold (P<0.05) and increased oxygen consumption rates by 2-fold (P<0.01). This latter effect was abolished upon addition of the selective iNOS inhibitor, 1400 W. Ad-WT-Hsp22 significantly increased global iNOS expression by about 2.5-fold (P<0.01), and also increased iNOS mitochondrial localization by 4.5 fold vs. ß-gal (P<0.05). Upon comparable overexpression, the N20-Hsp22 mutant did not show significant mitochondrial translocation or stimulation of mitochondrial respiration. Moreover, although N20-Hsp22 did increase global iNOS expression by 4.6-fold, it did not promote iNOS mitochondrial translocation. CONCLUSION: Translocation of both Hsp22 and iNOS to the mitochondria is necessary for Hsp22-mediated stimulation of oxidative phosphorylation.
Asunto(s)
Proteínas del Choque Térmico HSP20/fisiología , Mitocondrias Cardíacas/metabolismo , Proteínas Musculares/fisiología , Óxido Nítrico Sintasa de Tipo II/metabolismo , Animales , Células Cultivadas , Proteínas de Choque Térmico , Masculino , Ratones , Ratones Transgénicos , Mitocondrias Cardíacas/enzimología , Membranas Mitocondriales/metabolismo , Chaperonas Moleculares , Fosforilación Oxidativa , Transporte de Proteínas , Ratas , Ratas Sprague-DawleyRESUMEN
AIMS: Expression of the heat shock protein 22 (Hsp22) in the heart stimulates cardiac cell survival through activation of the Akt pathway and expression of the inducible nitric oxide (NO) synthase (iNOS), the mediator of ischaemic preconditioning and the most powerful prophylaxis against cardiac cell death. The goal of the present study was to elucidate the downstream effector by which Hsp22 and Akt increase iNOS expression. We tested both in vivo and in vitro the hypothesis that such an effector is the valosin-containing protein (VCP), an Akt substrate, which activates the transcription factor NF-κB, using a transgenic mouse with cardiac-specific over-expression of Hsp22, as well as isolated rat cardiac myocytes. METHODS AND RESULTS: Using two-dimensional gel electrophoresis and mass spectrometry combined with immunoprecipitation, we found that Hsp22 and Akt co-localize and interact together with VCP. Adeno-mediated over-expression of VCP in isolated cardiac myocytes activated NF-κB and dose-dependently increased the expression of iNOS, which was abolished upon NF-κB inhibition. Over-expression of a dominant-negative (DN) mutant of VCP did not increase iNOS expression. VCP, but not its DN mutant, protected against chelerythrine-induced apoptosis, which was suppressed by inhibition of either NF-κB or iNOS. VCP-mediated activation of the NF-κB/iNOS pathway was also prevented upon inhibition of Akt. CONCLUSION: We conclude that the Akt substrate, VCP, mediates the increased expression of iNOS downstream from Hsp22 through an NF-κB-dependent mechanism.
Asunto(s)
Adenosina Trifosfatasas/fisiología , Proteínas de Ciclo Celular/fisiología , Miocitos Cardíacos/fisiología , Óxido Nítrico Sintasa de Tipo II/fisiología , Adenosina Trifosfatasas/análisis , Animales , Proteínas de Ciclo Celular/análisis , Supervivencia Celular , Células Cultivadas , Proteínas del Choque Térmico HSP20/fisiología , Proteínas de Choque Térmico , Isoenzimas/fisiología , Masculino , Ratones , Chaperonas Moleculares , Proteínas Musculares/fisiología , Miocitos Cardíacos/citología , FN-kappa B/fisiología , Proteínas Proto-Oncogénicas c-akt/fisiología , Ratas , Ratas Sprague-Dawley , Proteína que Contiene ValosinaRESUMEN
H11 kinase/Hsp22 (Hsp22), a small heat shock protein upregulated by ischemia/reperfusion, provides cardioprotection equal to ischemic preconditioning (IPC) through a nitric oxide (NO)-dependent mechanism. A main target of NO-mediated preconditioning is the mitochondria, where NO reduces O2 consumption and reactive oxygen species (ROS) production during ischemia. Therefore, we tested the hypothesis that Hsp22 overexpression modulates mitochondrial function through an NO-sensitive mechanism. In cardiac mitochondria isolated from transgenic (TG) mice with cardiac-specific overexpression of Hsp22, mitochondrial basal, ADP-dependent, and uncoupled O2 consumption was increased in the presence of either glucidic or lipidic substrates. This was associated with a decrease in the maximal capabilities of complexes I and III to generate superoxide anion in combination with an inhibition of superoxide anion production by the reverse electron flow. NO synthase expression and NO production were increased in mitochondria from TG mice. Hsp22-induced increase in O2 consumption was abolished either by pretreatment of TG mice with the NO synthase inhibitor L-N(G)-nitroarginine methyl ester (L-NAME) or in isolated mitochondria by the NO scavenger phenyltetramethylimidazoline-1-oxyl-3-oxide. L-NAME pretreatment also restored the reverse electron flow. After anoxia, mitochondria from TG mice showed a reduction in both oxidative phosphorylation and H2O2 production, an effect partially reversed by L-NAME. Taken together, these results demonstrate that Hsp22 overexpression increases the capacity of mitochondria to produce NO, which stimulates oxidative phosphorylation in normoxia and decreases oxidative phosphorylation and reactive oxygen species production after anoxia. Such characteristics replicate those conferred by IPC, thereby placing Hsp22 as a potential tool for prophylactic protection of mitochondrial function during ischemia.
Asunto(s)
Proteínas del Choque Térmico HSP20/metabolismo , Corazón , Mitocondrias Cardíacas/metabolismo , Proteínas Musculares/metabolismo , Óxido Nítrico/metabolismo , Animales , Células Cultivadas , Proteínas del Choque Térmico HSP20/genética , Corazón/efectos de los fármacos , Corazón/fisiopatología , Proteínas de Choque Térmico , Isquemia/metabolismo , Ratones , Ratones Transgénicos , Chaperonas Moleculares , Proteínas Musculares/genética , NG-Nitroarginina Metil Éster/administración & dosificación , Especificidad de Órganos , Fosforilación Oxidativa/efectos de los fármacos , Consumo de Oxígeno/efectos de los fármacos , Consumo de Oxígeno/genética , Especies Reactivas de Oxígeno/metabolismo , Transgenes/genéticaRESUMEN
BACKGROUND: Cardiac overload, a major cause of heart failure, induces the expression of the heat shock protein H11 kinase/Hsp22 (Hsp22). METHODS AND RESULTS: To determine the specific function of Hsp22 in that context, a knockout mouse model of Hsp22 deletion was generated. Although comparable to wild-type mice in basal conditions, knockout mice exposed to pressure overload developed less hypertrophy and showed ventricular dilation, impaired contractile function, increased myocyte length and accumulation of interstitial collagen, faster transition into heart failure, and increased mortality. Microarrays revealed that hearts from knockout mice failed to transactivate genes regulated by the transcription factor STAT3. Accordingly, nuclear STAT3 tyrosine phosphorylation was decreased in knockout mice. Silencing and overexpression experiments in isolated neonatal rat cardiomyocytes showed that Hsp22 activates STAT3 via production of interleukin-6 by the transcription factor nuclear factor-κB. In addition to its transcriptional function, STAT3 translocates to the mitochondria where it increases oxidative phosphorylation. Both mitochondrial STAT3 translocation and respiration were also significantly decreased in knockout mice. CONCLUSIONS: This study found that Hsp22 represents a previously undescribed activator of both nuclear and mitochondrial functions of STAT3, and its deletion in the context of pressure overload in vivo accelerates the transition into heart failure and increases mortality.
Asunto(s)
Eliminación de Gen , Proteínas del Choque Térmico HSP20/genética , Insuficiencia Cardíaca/genética , Mitocondrias Cardíacas/genética , Proteínas Musculares/genética , Factor de Transcripción STAT3/genética , Animales , Cardiomegalia/enzimología , Cardiomegalia/genética , Núcleo Celular/enzimología , Núcleo Celular/genética , Células Cultivadas , Colágeno/metabolismo , Perfilación de la Expresión Génica , Insuficiencia Cardíaca/enzimología , Insuficiencia Cardíaca/mortalidad , Proteínas de Choque Térmico , Interleucina-6/biosíntesis , Masculino , Ratones , Ratones Noqueados , Mitocondrias Cardíacas/enzimología , Chaperonas Moleculares , Miocitos Cardíacos/enzimología , FN-kappa B/metabolismo , Fosforilación Oxidativa , RatasRESUMEN
The second window of ischemic preconditioning (SWOP) provides maximal protection against ischemia through regulation of the inducible nitric oxide synthase (iNOS), yet its application is limited by the inconvenience of the preliminary ischemic stimulus required for prophylaxis. Overexpression of H11 kinase/Hsp22 (Hsp22) in a transgenic mouse model provides cardioprotection against ischemia that is equivalent to that conferred by SWOP. We hypothesized that short-term, prophylactic overexpression of Hsp22 would offer an alternative to SWOP in reducing ischemic damage through a nitric oxide (NO)-dependent mechanism. Adeno-mediated overexpression of Hsp22 was achieved in the area at risk of the left circumflex (Cx) coronary artery in chronically instrumented swine and compared with LacZ controls (n = 5/group). Hsp22-injected myocardium showed an average fourfold increase in Hsp22 protein expression compared with controls and a doubling in iNOS expression (both P < 0.05). Four days after ischemia-reperfusion, regional wall thickening was reduced by 58 ± 2% in the Hsp22 group vs. 82 ± 7% in the LacZ group, and Hsp22 reduced infarct size by 40% (both P < 0.05 vs. LacZ). Treatment with the NOS inhibitor N(G)-nitro-L-arginine (L-NNA) before ischemia suppressed the protection induced by Hsp22. In isolated cardiomyocytes, Hsp22 increased iNOS expression through the transcription factors NF-κB and STAT, the same effectors activated by SWOP, and reduced by 60% H(2)O(2)-mediated apoptosis, which was also abolished by NOS inhibitors. Therefore, short-term, prophylactic conditioning by Hsp22 provides NO-dependent cardioprotection that reproduces the signaling of SWOP, placing Hsp22 as a potential alternative for preemptive treatment of myocardial ischemia.
Asunto(s)
Proteínas de Choque Térmico/biosíntesis , Precondicionamiento Isquémico Miocárdico/métodos , Isquemia Miocárdica/prevención & control , Miocardio/enzimología , Óxido Nítrico Sintasa de Tipo II/biosíntesis , Proteínas Serina-Treonina Quinasas/biosíntesis , Animales , Animales Modificados Genéticamente , Células Cultivadas , Vasos Coronarios/efectos de los fármacos , Vasos Coronarios/metabolismo , Vasos Coronarios/fisiología , Proteínas de Choque Térmico/genética , Ratones , Isquemia Miocárdica/enzimología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/enzimología , Miocitos Cardíacos/fisiología , FN-kappa B/metabolismo , Nitroarginina/farmacología , Proteínas Serina-Treonina Quinasas/genética , PorcinosRESUMEN
RATIONALE: Increased aortic stiffness, an important feature of many vascular diseases, eg, aging, hypertension, atherosclerosis, and aortic aneurysms, is assumed because of changes in extracellular matrix (ECM). OBJECTIVE: We tested the hypothesis that the mechanisms also involve intrinsic stiffening of vascular smooth muscle cells (VSMCs). METHODS AND RESULTS: Stiffness was measured in vitro both by atomic force microscopy (AFM) and in a reconstituted tissue model, using VSMCs from aorta of young versus old male monkeys (Macaca fascicularis) (n=7/group), where aortic stiffness increases by 200% in vivo. The apparent elastic modulus was increased (P<0.05) in old (41.7+/-0.5 kPa) versus young (12.8+/-0.3 kPa) VSMCs but not after disassembly of the actin cytoskeleton with cytochalasin D. Stiffness of the VSMCs in the reconstituted tissue model was also higher (P<0.05) in old (23.3+/-3.0 kPa) than in young (13.7+/-2.4 kPa). CONCLUSIONS: These data support the novel concept, not appreciated previously, that increased vascular stiffness with aging is attributable not only to changes in ECM but also to intrinsic changes in VSMCs.
Asunto(s)
Envejecimiento/patología , Enfermedades de la Aorta/patología , Músculo Liso Vascular/patología , Actinas/metabolismo , Factores de Edad , Envejecimiento/metabolismo , Animales , Aorta Torácica/patología , Enfermedades de la Aorta/etiología , Células Cultivadas , Citocalasina D/farmacología , Citoesqueleto/efectos de los fármacos , Citoesqueleto/metabolismo , Módulo de Elasticidad , Integrina beta1/metabolismo , Macaca fascicularis , Masculino , Microscopía de Fuerza Atómica , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/metabolismo , Tubulina (Proteína)/metabolismo , Vimentina/metabolismoRESUMEN
A major difference between experimental ischemic preconditioning (IPC), induced by brief ischemic episodes, and the clinical situation is that patients generally have repetitive episodes of ischemia. We used a swine model to examine differences in genes regulated by classical second-window IPC (SWOP) [two 10-min episodes of coronary artery occlusion (CAO) followed by 24 h reperfusion] compared with repetitive CAO/reperfusion (RCO), i.e., two 10-min CAO 12 h apart, and to repetitive coronary stenosis (RCS), six episodes of 90 min coronary stenosis 12 h apart (n = 5/group). All three models reduced infarct size by 60-85%, which was mediated by nitric oxide in SWOP but not in the other two models. We employed microarray analyses to discover additional molecular pathways intrinsic to models of repetitive ischemia and different from classical SWOP. There was an 85% homology in gene response between the RCO and RCS models, whereas SWOP was qualitatively different. Both RCO and RCS, but not SWOP, showed downregulation of genes encoding proteins involved in oxidative metabolism and upregulation of genes involved in protein synthesis, unfolded protein response, autophagy, heat shock response, protein secretion, and an activation of the NF-kappaB signaling pathway. Therefore, the regulated genes mediating IPC with repetitive ischemia differ radically from SWOP both quantitatively and qualitatively, showing that a repetitive pattern of ischemia, rather than the difference between no-flow vs. low-flow ischemia, dictates the genomic response of the heart. These findings illustrate new cardioprotective mechanisms developed by repetitive IPC, which are potentially more relevant to patients with chronic ischemic heart disease, who are subjected to repetitive episodes of ischemia.
Asunto(s)
Precondicionamiento Isquémico Miocárdico , Isquemia Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/metabolismo , Análisis de Varianza , Animales , Western Blotting , Circulación Coronaria/fisiología , Modelos Animales de Enfermedad , Regulación de la Expresión Génica , Isquemia Miocárdica/genética , Isquemia Miocárdica/fisiopatología , Daño por Reperfusión Miocárdica/genética , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , PorcinosRESUMEN
BACKGROUND: Therapy for chronic systolic heart failure (sHF) has improved over the past 2 decades, but the armamentarium of drugs is limited and consequently sHF remains a leading cause of death and disability. In this investigation, we examined the effects of a novel cardiac myosin activator, omecamtiv mecarbil (formerly CK-1827452) in 2 different models of heart failure. METHODS AND RESULTS: Two different models of sHF were used: (1) pacing-induced sHF after myocardial infarction (MI-sHF) and (2) pacing-induced sHF after 1 year of chronic pressure overload left ventricular hypertrophy (LVH-sHF). Omecamtiv mecarbil increased systolic function in sHF dogs, chronically instrumented to measure LV pressure, wall thickness, and cardiac output. Omecamtiv mecarbil, infused for 24 hours, induced a sustained increase without desensitization (P<0.05) in wall thickening (25+/-6.2%), stroke volume (44+/-6.5%) and cardiac output (22+/-2.8%), and decreased heart rate (15+/-3.0%). The major differences between the effect of omecamtiv mecarbil on cardiac function and the effect induced by a catecholamine, for example, dobutamine, is that omecamtiv mecarbil did not increase LV dP/dt but rather increased LV systolic ejection time by 26+/-2.9% in sHF. Another key difference is that myocardial O(2) consumption (MVO(2)), which increases with catecholamines, was not significantly affected by omecamtiv mecarbil. CONCLUSIONS: These results demonstrate that chronic infusion of the cardiac myosin activator, omecamtiv mecarbil, improves LV function in sHF without the limitations of progressive desensitization and increased MVO(2.) This unique profile may provide a new therapeutic approach for patients with sHF.
Asunto(s)
Miosinas Cardíacas/efectos de los fármacos , Insuficiencia Cardíaca Sistólica/tratamiento farmacológico , Contracción Miocárdica/efectos de los fármacos , Función Ventricular Izquierda/efectos de los fármacos , Análisis de Varianza , Animales , Miosinas Cardíacas/metabolismo , Estado de Conciencia , Modelos Animales de Enfermedad , Dobutamina/farmacología , Perros , Esquema de Medicación , Femenino , Insuficiencia Cardíaca Sistólica/fisiopatología , Pruebas de Función Cardíaca , Infusiones Intravenosas , Masculino , Infarto del Miocardio/tratamiento farmacológico , Infarto del Miocardio/fisiopatología , Consumo de Oxígeno/efectos de los fármacos , Probabilidad , Distribución Aleatoria , Volumen Sistólico/efectos de los fármacos , Resultado del Tratamiento , Urea/análogos & derivados , Urea/farmacología , Remodelación Ventricular/efectos de los fármacosRESUMEN
Activation of the ubiquitin-proteasome system has been described in different models of cardiac hypertrophy. Cardiac cell growth in response to pressure or volume overload, as well as physiological adaptive hypertrophy, is accompanied by an increase in protein ubiquitination, proteasome subunit expression, and proteasome activity. Importantly, an inhibition of proteasome activity prevents and reverses cardiac hypertrophy and remodelling in vivo. The focus of this review is to provide an update about the mechanisms by which proteasome inhibitors affect cardiac cell growth in adaptive and maladaptive models of cardiac hypertrophy. In the first part, we summarize how the proteasome affects both proteolysis and protein synthesis in a context of cardiac cell growth. In the second part, we show how proteasome inhibition can prevent and reverse cardiac hypertrophy and remodelling in response to different conditions of overload.