RESUMEN
The production of influenza vaccines in plants is achieved through transient expression of viral hemagglutinins (HAs), a process mediated by the bacterial vector Agrobacterium tumefaciens. HA proteins are then produced and matured through the secretory pathway of plant cells, before being trafficked to the plasma membrane where they induce formation of virus-like particles (VLPs). Production of VLPs unavoidably impacts plant cells, as do viral suppressors of RNA silencing (VSRs) that are co-expressed to increase recombinant protein yields. However, little information is available on host molecular responses to foreign protein expression. This work provides a comprehensive overview of molecular changes occurring in Nicotiana benthamiana leaf cells transiently expressing the VSR P19, or co-expressing P19 and an influenza HA. Our data identifies general responses to Agrobacterium-mediated expression of foreign proteins, including shutdown of chloroplast gene expression, activation of oxidative stress responses and reinforcement of the plant cell wall through lignification. Our results also indicate that P19 expression promotes salicylic acid (SA) signalling, a process dampened by co-expression of the HA protein. While reducing P19 level, HA expression also induces specific signatures, with effects on lipid metabolism, lipid distribution within membranes and oxylipin-related signalling. When producing VLPs, dampening of P19 responses thus likely results from lower expression of the VSR, crosstalk between SA and oxylipin pathways, or a combination of both outcomes. Consistent with the upregulation of oxidative stress responses, we finally show that reduction of oxidative stress damage through exogenous application of ascorbic acid improves plant biomass quality during production of VLPs.
Asunto(s)
Vacunas contra la Influenza , Gripe Humana , Orthomyxoviridae , Humanos , Nicotiana/genética , Plantas Modificadas Genéticamente/genética , Oxilipinas/metabolismo , Agrobacterium tumefaciens/genética , Orthomyxoviridae/genética , Hojas de la Planta/genéticaRESUMEN
The aim of the study was to characterize if the development of cardiac hypertrophy (CH) caused by severe left ventricle (LV) volume overload (VO) from chronic aortic valve regurgitation (AR) in male rats was influenced by androgens. We studied Wistar rats with/without orchiectomy (Ocx) either sham-operated (S) or with severe AR for 26 weeks. Loss of testosterone induced by Ocx decreased general body growth. Cardiac hypertrophy resulting from AR was relatively more important in intact (non-Ocx) animals than in Ocx ones compared to their respective S group (60% vs. 40%; P = 0.019). The intact AR group had more LV dilation, end-diastolic LV diameter being increased by 37% over S group and by 17% in AROcx rats (P < 0.0001). Fractional shortening (an index of systolic function) decreased only by 15% in AROcx compared to 26% for intact AR animals (P = 0.029). Changes in LV gene expression resulting from CH were more marked in intact rats than in AROcx animals, especially for genes linked to extracellular matrix remodeling and energy metabolism. The ratio of hydroxyacyl-Coenzyme A dehydrogenase activity over hexokinase activity, an index of the shift of myocardial substrate use toward glucose from the preferred fatty acids, was significantly decreased in the AR group but not in AROcx. Finally, pJnk2 LV protein content was more abundant in AR than in AROcx rats, indicating decreased activation of this stress pathway in the absence of androgens. In summary, testosterone deficiency in rats with severe LV VO resulted in less CH and a normalization of the LV gene expression profile.
Asunto(s)
Cardiomegalia/prevención & control , Testosterona/deficiencia , Animales , Insuficiencia de la Válvula Aórtica/complicaciones , Biomarcadores/metabolismo , Cardiomegalia/diagnóstico por imagen , Cardiomegalia/etiología , Cardiomegalia/metabolismo , Modelos Animales de Enfermedad , Ecocardiografía , Metabolismo Energético/fisiología , Matriz Extracelular/metabolismo , Regulación de la Expresión Génica/fisiología , Ventrículos Cardíacos/metabolismo , Hemodinámica/fisiología , Masculino , Orquiectomía , Ratas Wistar , Transducción de Señal/fisiología , Testosterona/fisiología , Función Ventricular Izquierda/fisiología , Remodelación Ventricular/fisiologíaRESUMEN
Cardiac hypertrophy (CH) is an important and independent predictor of morbidity and mortality. Through expression profiling, we recently identified a subset of genes (Dhrs7c, Decr, Dhrs11, Dhrs4, Hsd11b1, Hsd17b10, Hsd17b8, Blvrb, Pecr), all of which are members of the short-chain dehydrogenase/reductase (SDR) superfamily and are highly expressed in the heart, that were significantly dysregulated in a rat model of CH caused by severe aortic valve regurgitation (AR). Here, we studied their expression in various models of CH, as well as factors influencing their regulation. Among the nine SDR genes studied, all but Hsd11b1 were down-regulated in CH models (AR rats or mice infused with either isoproterenol or angiotensin II). This regulation showed a clear sex dimorphism, being more evident in males than in females irrespective of CH levels. In neonatal rat cardiomyocytes, we observed that treatment with the α1-adrenergic receptor agonist phenylephrine mostly reproduced the observations made in CH animals models. Retinoic acid, on the other hand, stimulated the expression of most of the SDR genes studied, suggesting that their expression may be related to cardiomyocyte differentiation. Indeed, levels of expression were found to be higher in the hearts of adult animals than in neonatal cardiomyocytes. In conclusion, we identified a group of genes modulated in animal models of CH and mostly in males. This could be related to the activation of the fetal gene expression program in pathological CH situations, in which these highly expressed genes are down-regulated in the adult heart.
RESUMEN
Aortic valve regurgitation (AR) imposes a volume overload (VO) to the left ventricle (LV). Male rats with a pathological heart overload usually progress more quickly towards heart failure than females. We examined whether a sexual dimorphism exists in the myocardial transcriptional adaptations to AR. Adult Wistar male and female rats either underwent a sham operation or were induced with AR and then followed for 26 weeks. Female AR rats gained relatively more LV mass than males (75 vs. 42%). They had a similar increase in LV chamber dimensions compared to males but more wall thickening. On the other hand, fatty acid oxidation (FAO)-related LV enzyme activity was only decreased in AR males. The expression of genes encoding FAO-related enzymes was only reduced in AR males and not in females. A similar situation was observed for the expression of genes involved in mitochondrial biogenesis or function as well as for genes encoding for transcription factors implicated in the control of bioenergetics and mitochondrial function (Errα, Errγ or Pgc1α). Although females develop more LV hypertrophy from severe VO, their myocardial gene expression remains closer to normal. This could provide survival benefits for females with severe VO.
Asunto(s)
Cardiomegalia/genética , Cardiomegalia/fisiopatología , Hipertrofia Ventricular Izquierda/genética , Hipertrofia Ventricular Izquierda/fisiopatología , Transcripción Genética , Disfunción Ventricular Izquierda/genética , Disfunción Ventricular Izquierda/fisiopatología , Animales , Biomarcadores , Biopsia , Cardiomegalia/diagnóstico por imagen , Cardiomegalia/patología , Modelos Animales de Enfermedad , Ecocardiografía , Metabolismo Energético , Femenino , Pruebas de Función Cardíaca , Hemodinámica , Hipertrofia Ventricular Izquierda/diagnóstico por imagen , Hipertrofia Ventricular Izquierda/patología , Masculino , Mitocondrias Cardíacas/metabolismo , Ratas , Factores Sexuales , Remodelación VentricularRESUMEN
Patients with left ventricle (LV) volume overload (VO) remain in a compensated state for many years although severe dilation is present. The myocardial capacity to fulfill its energetic demand may delay decompensation. We performed a gene expression profile, a model of chronic VO in rat LV with severe aortic valve regurgitation (AR) for 9 months, and focused on the study of genes associated with myocardial energetics. Methods. LV gene expression profile was performed in rats after 9 months of AR and compared to sham-operated controls. LV glucose and fatty acid (FA) uptake was also evaluated in vivo by positron emission tomography in 8-week AR rats treated or not with fenofibrate, an activator of FA oxidation (FAO). Results. Many LV genes associated with mitochondrial function and metabolism were downregulated in AR rats. FA ß-oxidation capacity was significantly impaired as early as two weeks after AR. Treatment with fenofibrate, a PPARα agonist, normalized both FA and glucose uptake while reducing LV dilation caused by AR. Conclusion. Myocardial energy substrate preference is affected early in the evolution of LV-VO cardiomyopathy. Maintaining a relatively normal FA utilization in the myocardium could translate into less glucose uptake and possibly lesser LV remodeling.
Asunto(s)
Insuficiencia de la Válvula Aórtica/genética , Metabolismo Energético/genética , Insuficiencia Cardíaca/genética , Hipertrofia Ventricular Izquierda/genética , Animales , Insuficiencia de la Válvula Aórtica/tratamiento farmacológico , Insuficiencia de la Válvula Aórtica/fisiopatología , Volumen Cardíaco/genética , Modelos Animales de Enfermedad , Fenofibrato/administración & dosificación , Insuficiencia Cardíaca/tratamiento farmacológico , Insuficiencia Cardíaca/fisiopatología , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/fisiopatología , Humanos , Hipertrofia Ventricular Izquierda/metabolismo , Hipertrofia Ventricular Izquierda/fisiopatología , Mitocondrias Cardíacas/genética , Oxidación-Reducción , PPAR alfa/genética , Ratas , Transcriptoma , Función Ventricular Izquierda/efectos de los fármacos , Función Ventricular Izquierda/genéticaRESUMEN
BACKGROUND: Hypertrophy (H) is an adaptive response of the heart to a hemodynamic overload. Severe left ventricular (LV) volume overload (VO) from valve regurgitations (aortic (AR) or mitral regurgitation) leads to eccentric LVH. Increased protein turnover is a major event during development of LVH and the mechanistic target of rapamycin (mTOR) is a key molecule for its control. The role of mTOR inhibition in the development of LVH using rapamycin for relatively short periods of time (days to a few weeks) has been studied in the past in pressure overload models but not in VO models. We investigated if mTOR pathway was activated during LVH development in a model of severe VO (AR) in rats and if a rapamycin treatment can slow heart remodeling in this situation. METHODS AND RESULTS: Male rats with severe AR were studied acutely at 2 days, at 8 weeks (compensated phase) and 6 months (late phase) after VO induction. mTOR complex (mTORC) 1 (ribosomal S6 protein phosphorylation) was activated early after AR induction but not later in the disease whereas mTORC2 activity levels (Akt phosphorylation at Ser473) remained stable. We observed that a moderate dose of rapamycin (2 mg/kg/day; orally) for 8 weeks prevented severe LVH caused by AR (-46 %: p < 0.001). Rapamycin treatment specifically inhibited LV mTORC1 without altering mTORC2 activity at 8 weeks. Rapamycin also prevented cardiac myocyte hypertrophy caused by AR. CONCLUSION: Rapamycin slows hypertrophy in LV VO by inhibiting early activation of mTORC1 without modulating mTORC2.
RESUMEN
BACKGROUND: Patients with chronic aortic valve regurgitation (AR) causing left ventricular (LV) volume overload can remain asymptomatic for many years despite having a severely dilated heart. The sudden development of heart failure is not well understood but alterations of myocardial energy metabolism may be contributive. We studied the evolution of LV energy metabolism in experimental AR. METHODS: LV glucose utilization was evaluated in vivo by positron emission tomography (microPET) scanning of 6-month AR rats. Sham-operated or AR rats (n = 10-30 animals/group) were evaluated 3, 6 or 9 months post-surgery. We also tested treatment intervention in order to evaluate their impact on metabolism. AR rats (20 animals) were trained on a treadmill 5 times a week for 9 months and another group of rats received a beta-blockade treatment (carvedilol) for 6 months. RESULTS: MicroPET revealed an abnormal increase in glucose consumption in the LV free wall of AR rats at 6 months. On the other hand, fatty acid beta-oxidation was significantly reduced compared to sham control rats 6 months post AR induction. A significant decrease in citrate synthase and complex 1 activity suggested that mitochondrial oxidative phosphorylation was also affected maybe as soon as 3 months post-AR.Moderate intensity endurance training starting 2 weeks post-AR was able to partially normalize the activity of various myocardial enzymes implicated in energy metabolism. The same was true for the AR rats treated with carvedilol (30 mg/kg/d). Responses to these interventions were different at the level of gene expression. We measured mRNA levels of a number of genes implicated in the transport of energy substrates and we observed that training did not reverse the general down-regulation of these genes in AR rats whereas carvedilol normalized the expression of most of them. CONCLUSION: This study shows that myocardial energy metabolism remodeling taking place in the dilated left ventricle submitted to severe volume overload from AR can be partially avoided by exercise or beta-blockade in rats.
Asunto(s)
Antagonistas de Receptores Adrenérgicos beta 1/farmacología , Insuficiencia de la Válvula Aórtica/metabolismo , Metabolismo Energético/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Condicionamiento Físico Animal , Resistencia Física , Animales , Insuficiencia de la Válvula Aórtica/diagnóstico por imagen , Modelos Animales de Enfermedad , Regulación hacia Abajo , Glucosa/metabolismo , Ventrículos Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/efectos de los fármacos , Masculino , Miocardio/metabolismo , Ratas Wistar , UltrasonografíaRESUMEN
BACKGROUND: The composition of a diet can influence myocardial metabolism and development of left ventricular hypertrophy (LVH). The impact of a high-fat diet in chronic left ventricular volume overload (VO) causing eccentric LVH is unknown. This study examined the effects of chronic ingestion of a high-fat diet in rats with chronic VO caused by severe aortic valve regurgitation (AR) on LVH, function and on myocardial energetics and survival. METHODS: Male Wistar rats were divided in four groups: Shams on control or high-fat (HF) diet (15 rats/group) and AR rats fed with the same diets (ARC (n = 56) and ARHF (n = 32)). HF diet was started one week before AR induction and the protocol was stopped 30 weeks later. RESULTS: As expected, AR caused significant LV dilation and hypertrophy and this was exacerbated in the ARHF group. Moreover, survival in the ARHF group was significantly decreased compared the ARC group. Although the sham animals on HF also developed significant obesity compared to those on control diet, this was not associated with heart hypertrophy. The HF diet in AR rats partially countered the expected shift in myocardial energy substrate preference usually observed in heart hypertrophy (from fatty acids towards glucose). Systolic function was decreased in AR rats but HF diet had no impact on this parameter. The response to HF diet of different fatty acid oxidation markers as well as the increase in glucose transporter-4 translocation to the plasma membrane compared to ARC was blunted in AR animals compared to those on control diet. CONCLUSIONS: HF diet for 30 weeks decreased survival of AR rats and worsened eccentric hypertrophy without affecting systolic function. The expected adaptation of myocardial energetics to volume-overload left ventricle hypertrophy in AR animals seemed to be impaired by the high-fat diet suggesting less metabolic flexibility.
Asunto(s)
Insuficiencia de la Válvula Aórtica/complicaciones , Dieta Alta en Grasa/efectos adversos , Hipertrofia Ventricular Izquierda/etiología , Obesidad/complicaciones , Adaptación Fisiológica , Animales , Insuficiencia de la Válvula Aórtica/diagnóstico , Insuficiencia de la Válvula Aórtica/metabolismo , Insuficiencia de la Válvula Aórtica/fisiopatología , Modelos Animales de Enfermedad , Metabolismo Energético , Ácidos Grasos/metabolismo , Factores de Transcripción Forkhead/metabolismo , Glucosa/metabolismo , Transportador de Glucosa de Tipo 4/metabolismo , Glucógeno Sintasa Quinasa 3/metabolismo , Glucógeno Sintasa Quinasa 3 beta , Hipertrofia Ventricular Izquierda/diagnóstico , Hipertrofia Ventricular Izquierda/metabolismo , Hipertrofia Ventricular Izquierda/fisiopatología , Masculino , Miocardio/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Obesidad/metabolismo , Obesidad/fisiopatología , Oxidación-Reducción , Ratas Wistar , Factores de Riesgo , Factores de Tiempo , Función Ventricular IzquierdaRESUMEN
BACKGROUND: Aortic valve regurgitation (AR) is a volume-overload disease causing severe eccentric left ventricular (LV) hypertrophy and eventually heart failure. There is currently no approved drug to treat patients with AR. Many vasodilators including angiotensin-converting enzyme inhibitors have been evaluated in clinical trials, but although some results were promising, others were inconclusive. Overall, no drug has yet been able to improve clinical outcome in AR and the controversy remains. We have previously shown in an animal model that captopril (Cpt) reduced LV hypertrophy and protected LV systolic function, but we had not evaluated the clinical outcome. This protocol was designed to evaluate the effects of a long-term Cpt treatment on survival in the same animal model of severe aortic valve regurgitation. METHODS AND RESULTS: Forty Wistar rats with AR were treated or untreated with Cpt (1 g/L in drinking water) for a period of 7 months to evaluate survival, myocardial remodeling, and function by echocardiography as well as myocardial metabolism by µ positron emission tomography scan. Survival was significantly improved in Cpt-treated animals with a survival benefit visible as soon as after 4 months of treatment. Cpt reduced LV dilatation and LV hypertrophy. It also significantly improved the myocardial metabolic profile by restoring the level of fatty acids metabolic enzymes and use. CONCLUSIONS: In a controlled animal model of pure severe aortic valve regurgitation, Cpt treatment reduced LV remodeling and LV hypertrophy and improved myocardial metabolic profile and survival. These results support the need to reevaluate the role of angiotensin-converting enzyme inhibitors in humans with AR in a large, carefully designed prospective clinical trial.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Insuficiencia de la Válvula Aórtica/tratamiento farmacológico , Captopril/farmacología , Metabolismo Energético/efectos de los fármacos , Miocardio/enzimología , Remodelación Ventricular/efectos de los fármacos , Animales , Insuficiencia de la Válvula Aórtica/diagnóstico , Insuficiencia de la Válvula Aórtica/enzimología , Insuficiencia de la Válvula Aórtica/fisiopatología , Modelos Animales de Enfermedad , Ecocardiografía , Matriz Extracelular/metabolismo , Ácidos Grasos/metabolismo , Quinasa 5 del Receptor Acoplado a Proteína-G/metabolismo , Hipertrofia Ventricular Izquierda/diagnóstico , Hipertrofia Ventricular Izquierda/enzimología , Hipertrofia Ventricular Izquierda/fisiopatología , Hipertrofia Ventricular Izquierda/prevención & control , Miocardio/patología , Tomografía de Emisión de Positrones , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Índice de Severidad de la Enfermedad , Factores de Tiempo , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
AIMS: Fenofibrate is a peroxisome proliferator-associated receptor alpha agonist (PPARα) used clinically for the management of dyslipidemia and is a myocardial fatty acid oxidation stimulator. It has also been shown to have cardiac anti-hypertrophic properties but the effects of fenofibrate on the development of eccentric LVH and ventricular function in chronic left ventricular (LV) volume overload (VO) are unknown. This study was therefore designed to explore the effects of fenofibrate treatment in a VO rat model caused by severe aortic valve regurgitation (AR) with a focus on cardiac remodeling and myocardial metabolism. MAIN METHODS: Male Wistar rats were divided in four groups (13-15 animals/group): Shams (S) treated with fenofibrate (F; 100 mg/kg/d PO) or not (C) and severe AR receiving or not fenofibrate. Treatment was started one week before surgery and the animals were sacrificed 9 weeks later. KEY FINDINGS: AR rats developed severe LVH (increased LV weight) during the course of the protocol. Fenofibrate did not reduce LV weight. However, eccentric LV remodeling was strongly reduced by fenofibrate in AR animals. Fractional shortening was significantly less affected in ARF compared to ARC group. Fenofibrate also increased the myocardial enzymatic activity of enzymes associated with fatty acid oxidation while inhibiting glycolytic enzyme phosphofructokinase. SIGNIFICANCE: Fenofibrate decreased LV eccentric remodeling associated with severe VO and helped maintain systolic function. Studies with a longer follow-up will be needed to assess the long-term effects of fenofibrate in chronic volume overload caused by aortic regurgitation.
Asunto(s)
Insuficiencia de la Válvula Aórtica/tratamiento farmacológico , Fenofibrato/farmacología , Hipolipemiantes/farmacología , Disfunción Ventricular Izquierda/tratamiento farmacológico , Remodelación Ventricular/efectos de los fármacos , Animales , Insuficiencia de la Válvula Aórtica/complicaciones , Insuficiencia de la Válvula Aórtica/fisiopatología , Modelos Animales de Enfermedad , Ácidos Grasos/metabolismo , Masculino , Oxidación-Reducción/efectos de los fármacos , Fosfofructoquinasas/antagonistas & inhibidores , Ratas , Ratas Wistar , Índice de Severidad de la Enfermedad , Factores de Tiempo , Disfunción Ventricular Izquierda/etiología , Disfunción Ventricular Izquierda/fisiopatologíaRESUMEN
BACKGROUND AND AIM OF THE STUDY: Aortic regurgitation (AR) is a disease for which there is currently no effective medical treatment. It has been shown previously in an experimental model of AR that the renin-angiotensin-aldosterone system (RAAS) plays a major role, and that medications blocking the RAAS are effective to protect against left ventricular (LV) hypertrophy and also help to maintain a normal systolic function. The role of aldosterone receptor blockers in this disease has never been evaluated. Thus, the effects were studied of the aldosterone receptor blocking agent spironolactone in a model of chronic AR in rats. METHODS: The effects of a six-month treatment with spironolactone were evaluated in adult Wistar rats with severe AR, compared to sham-operated and untreated AR animals. RESULTS: Spironolactone treatment decreased the total heart weight. In addition, the LV expression of atrial natriuretic peptide mRNA was decreased by spironolactone treatment, as was the expression of collagen 1 and LOX1 mRNAs. Left ventricular fibrosis was decreased by spironolactone treatment. CONCLUSION: Spironolactone protected against volume-overload cardiomyopathy in this model of aortic valve regurgitation. The predominant protective effect was a decrease in myocardial fibrosis.
Asunto(s)
Insuficiencia de la Válvula Aórtica/tratamiento farmacológico , Cardiomegalia/tratamiento farmacológico , Antagonistas de Receptores de Mineralocorticoides/farmacología , Espironolactona/farmacología , Animales , Insuficiencia de la Válvula Aórtica/diagnóstico por imagen , Insuficiencia de la Válvula Aórtica/fisiopatología , Presión Sanguínea/efectos de los fármacos , Cardiomegalia/diagnóstico por imagen , Cardiomegalia/fisiopatología , Enfermedad Crónica , Diástole/fisiología , Modelos Animales de Enfermedad , Ecocardiografía , Frecuencia Cardíaca/efectos de los fármacos , Masculino , Ratas , Ratas Wistar , Presión Ventricular/fisiologíaRESUMEN
BACKGROUND: Aortic regurgitation (AR) is a chronic disease for which there is currently no approved medical treatment. We previously reported in an animal model that ß-blockade with metoprolol exerted beneficial effects on left ventricular remodeling and survival. Despite the recent publication of promising human data, ß-blockade in chronic AR remains controversial. More data are needed to support this potentially new treatment strategy. We hypothesized that carvedilol might be another safe treatment option in chronic AR, considering its combined ß-blocking and α-blocking effects and proven efficacy in patients with established heart failure. METHODS AND RESULTS: The effects of a 6-month treatment with carvedilol 30 mg/kg/d orally were evaluated in adult Wistar rats with severe AR. Sham-operated and untreated AR animals were used as controls. Carvedilol treatment resulted in less left ventricular hypertrophy and dilatation. Ejection fraction was improved and filling pressures were reduced by carvedilol. ß1-Receptor expression was also improved as well as myocardial capillary density. Those beneficial effects were noted despite the presence of drug-induced bradycardia. CONCLUSIONS: Carvedilol exerted protective effects against volume-overload cardiomyopathy in this model of aortic valve regurgitation with preserved ejection fraction. These results suggest a protective class effect of ß-blockers. Combined with the recent publication of promising human data, our findings support the need to carefully design a prospective study in humans to evaluate the effects of ß-blockers in chronic aortic valve regurgitation.
Asunto(s)
Antagonistas Adrenérgicos beta/farmacología , Insuficiencia de la Válvula Aórtica/tratamiento farmacológico , Carbazoles/farmacología , Propanolaminas/farmacología , Administración Oral , Antagonistas Adrenérgicos beta/administración & dosificación , Antagonistas Adrenérgicos beta/efectos adversos , Animales , Insuficiencia de la Válvula Aórtica/complicaciones , Insuficiencia de la Válvula Aórtica/diagnóstico por imagen , Insuficiencia de la Válvula Aórtica/genética , Insuficiencia de la Válvula Aórtica/fisiopatología , Factor Natriurético Atrial/genética , Bradicardia/inducido químicamente , Capilares/efectos de los fármacos , Capilares/fisiopatología , Carbazoles/administración & dosificación , Carbazoles/efectos adversos , Carvedilol , Enfermedad Crónica , Modelos Animales de Enfermedad , Proteínas de la Matriz Extracelular/genética , Proteínas Relacionadas con la Folistatina/genética , Regulación de la Expresión Génica , Frecuencia Cardíaca/efectos de los fármacos , Hipertrofia Ventricular Izquierda/etiología , Hipertrofia Ventricular Izquierda/prevención & control , Masculino , Péptido Natriurético Encefálico/genética , Propanolaminas/administración & dosificación , Propanolaminas/efectos adversos , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Receptores Adrenérgicos/genética , Volumen Sistólico/efectos de los fármacos , Factores de Tiempo , Ultrasonografía , Función Ventricular Izquierda/efectos de los fármacos , Presión Ventricular/efectos de los fármacosRESUMEN
BACKGROUND AND AIM OF THE STUDY: The calcification of cardiac valves is more frequently observed on left-sided (aortic or mitral) than right-sided (pulmonic or tricuspid) valves. The cause of this preferential left-sided calcification remains relatively unknown. The study aim was to evaluate the capacity of interstitial cells isolated from the four cardiac valves of healthy adult pigs to calcify in culture. METHODS: Interstitial cells were isolated from the valve leaflets of three healthy young pigs and cultured in DMEM/fetal bovine serum (10%) in the presence or absence of osteogenic additives (ascorbic acid, dexamethasone, beta-glycerophosphate). RESULTS: The proliferation rate was similar for cells from each of the four valves. After longer periods of culture (> 10 days), cells from each valve spontaneously formed several calcification nodules, the process being accelerated in the presence of osteogenic additives (to 4-7 days). Alkaline phosphatase (AP) activity was highest in cells originating from the aortic and mitral valves, respectively, and least in those from the pulmonic and tricuspid valves. Culture with the osteogenic additives increased the AP activity by at least 50% for each valve, but the relative AP activity between cells from each valve origin tended to remain similar (aortic > mitral > pulmonic > tricuspid). Interestingly, the levels of matrix Gla-protein mRNA (an endogenous calcification inhibitor) followed an opposite trend of expression for each valve. CONCLUSION: Interstitial cells from porcine cardiac valves share similarities, although the capacity to calcify is more evident in cells from valves of the left side of the heart. Interstitial cells from the aortic valve displayed the greatest potential for calcification.
Asunto(s)
Calcinosis/patología , Células del Tejido Conectivo/patología , Válvulas Cardíacas/patología , Fosfatasa Alcalina/metabolismo , Animales , Proliferación Celular , Células Cultivadas , Células del Tejido Conectivo/metabolismo , Válvulas Cardíacas/metabolismo , PorcinosRESUMEN
BACKGROUND: Aortic regurgitation (AR) is a disease of chronic left ventricular (LV) volume overload. Over time, AR will lead to LV dilatation, hypertrophy, and loss of function. There is currently no medical treatment proven effective to slow the evolution of this cardiomyopathy. Vasodilators were once thought to have protective effects, but recent publications have cast some doubts about their effectiveness. We hypothesized that drugs targeting the renin-angiotensin system should be more effective than those having no direct effect on the renin-angiotensin system. METHODS AND RESULTS: We designed a protocol comparing the effects of 3 vasodilators in a rat AR model (n=9 to 11 animals per group). The effects of a 6-month treatment of (1) nifedipine, (2) captopril, or (3) losartan were compared in male AR rats. Sham-operated and untreated AR animals were used as controls. Nifedipine-treated animals displayed hemodynamics, LV dilatation, hypertrophy, and loss of function similar to those of the untreated group. Both captopril and losartan were effective in improving hemodynamics, slow LV dilatation, hypertrophy, and dysfunction. Gene expression analysis confirmed the lack of effects of the nifedipine treatment at the molecular level. CONCLUSIONS: Using an animal model of severe AR, we found that vasodilators targeting the renin-angiotensin system were effective to slow the development of LV remodeling and to preserve LV function. As recently shown in the most recent human clinical trial, nifedipine was totally ineffective. Targeting the renin-angiotensin system seems a promising avenue in the treatment of this disease, and clinical trials should be carefully designed to re-evaluate the effectiveness of angiotensin I-converting enzyme inhibitors or angiotensin II receptor blockers in AR.
Asunto(s)
Insuficiencia de la Válvula Aórtica/complicaciones , Cardiomiopatía Dilatada/tratamiento farmacológico , Hipertrofia Ventricular Izquierda/tratamiento farmacológico , Vasodilatadores/uso terapéutico , Función Ventricular Izquierda/fisiología , Bloqueadores del Receptor Tipo 1 de Angiotensina II/administración & dosificación , Bloqueadores del Receptor Tipo 1 de Angiotensina II/uso terapéutico , Inhibidores de la Enzima Convertidora de Angiotensina/administración & dosificación , Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Animales , Captopril/administración & dosificación , Captopril/uso terapéutico , Cardiomiopatía Dilatada/etiología , Cardiomiopatía Dilatada/fisiopatología , Enfermedad Crónica , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Ecocardiografía Doppler , Estudios de Seguimiento , Hipertrofia Ventricular Izquierda/etiología , Hipertrofia Ventricular Izquierda/fisiopatología , Losartán/administración & dosificación , Losartán/uso terapéutico , Masculino , Nifedipino/administración & dosificación , Nifedipino/uso terapéutico , Ratas , Ratas Wistar , Sistema Renina-Angiotensina/efectos de los fármacos , Resultado del Tratamiento , Vasodilatadores/administración & dosificación , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
BACKGROUND: Exercise training has beneficial effects in patients with heart failure, although there is still no clear evidence that it may impact on their survival. There are no data regarding the effects of exercise in subjects with chronic left ventricular (LV) volume overload. Using a rat model of severe aortic valve regurgitation (AR), we studied the effects of long-term exercise training on survival, development of heart failure, and LV myocardial remodeling. METHODS AND RESULTS: One hundred sixty male adult rats were divided in 3 groups: sham sedentary (n=40), AR sedentary (n=80), and AR trained (n=40). Training consisted in treadmill running for up to 30 minutes, 5 times per week for 9 months, at a maximal speed of 20 m/minute. All sham-operated animals survived the entire course of the protocol. After 9 months, 65% of trained animals were alive compared with 46% of sedentary ones (P=0.05). Ejection fractions remained in the normal range (all above 60%) and LV masses between AR groups were similar. There was significantly less LV fibrosis in the trained group and lower LV filling pressures and improved echocardiographic diastolic parameters. Heart rate variability was also improved by exercise. CONCLUSIONS: Our data show that moderate endurance training is safe, does not increase the rate of developing heart failure, and most importantly, improves survival in this animal model of chronic LV volume overload. Exercise improved LV diastolic function, heart rate variability, and reduced myocardial fibrosis.
Asunto(s)
Insuficiencia de la Válvula Aórtica/complicaciones , Terapia por Ejercicio , Insuficiencia Cardíaca/terapia , Disfunción Ventricular Izquierda/terapia , Remodelación Ventricular , Animales , Insuficiencia de la Válvula Aórtica/fisiopatología , Presión Sanguínea , Modelos Animales de Enfermedad , Fibrosis , Regulación de la Expresión Génica , Insuficiencia Cardíaca/diagnóstico por imagen , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/fisiopatología , Frecuencia Cardíaca , Masculino , Miocardio/metabolismo , Miocardio/patología , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Índice de Severidad de la Enfermedad , Factores de Tiempo , Ultrasonografía , Disfunción Ventricular Izquierda/diagnóstico por imagen , Disfunción Ventricular Izquierda/etiología , Disfunción Ventricular Izquierda/fisiopatología , Presión VentricularRESUMEN
BACKGROUND: Aortic valve regurgitation (AR) imposes a pathologic volume overload to the left ventricle (LV), whereas aerobic exercise causes physiologic volume overloading. The impact of combining both LV volume overloads (pathologic and physiologic) is unknown. Considering the known beneficial effects of aerobic training on the cardiovascular system, we hypothesized that the positive effects would outweigh the negative ones and that exercise would improve the tolerance of the LV to AR. METHODS: Forty female adult Wistar rats were randomly divided in the following groups: 1) sham sedentary (SS), 2) sham trained (ST), 3) AR sedentary (ARS), and 4) AR trained (ART). Training consisted in treadmill running for 30 min five times per week at 20 m x s(-1) for 24 wk. In vivo follow-up was made by echocardiography and invasive intracardiac pressure measurements. Hearts were harvested for tissue analysis. RESULTS: Echocardiography revealed less LV dilation and hypertrophy in ART versus ARS as well as improved myocardial performance index. LV ejection fractions remained similar and within normal range in ART versus ARS. Invasive cardiac pressures yielded improved dP/dt- in ART versus ARS but similar dP/dt+. beta(1)-Adrenergic receptor mRNA expression was improved in the ART group versus ARS. CONCLUSION: Our data suggest that a moderate aerobic exercise program helps minimize LV dilation and hypertrophy and improves diastolic cardiac performance in heart submitted to chronic volume overload due to severe aortic valve regurgitation in this animal model.
Asunto(s)
Insuficiencia de la Válvula Aórtica/fisiopatología , Cardiomiopatía Hipertrófica/fisiopatología , Tolerancia al Ejercicio , Hipertrofia Ventricular Izquierda/fisiopatología , Animales , Insuficiencia de la Válvula Aórtica/diagnóstico por imagen , Insuficiencia de la Válvula Aórtica/prevención & control , Cardiomiopatía Hipertrófica/diagnóstico por imagen , Cardiomiopatía Hipertrófica/prevención & control , Modelos Animales de Enfermedad , Femenino , Hemodinámica , Hipertrofia Ventricular Izquierda/diagnóstico por imagen , Hipertrofia Ventricular Izquierda/prevención & control , Ratas , UltrasonografíaRESUMEN
Aortic valve regurgitation (AR) imposes a severe volume overload to the left ventricle (LV), which results in dilation, eccentric hypertrophy, and eventually loss of function. Little is known about the impact of AR on LV gene expression. We, therefore, conducted a gene expression profiling study in the LV of rats with acute and severe AR. We identified 64 genes that were specifically upregulated and 29 that were downregulated out of 21,910 genes after 2 wk. Of the upregulated genes, a good proportion was related to the extracellular matrix. We subsequently studied a subset of 19 genes by quantitative RT-PCR (qRT-PCR) to see if the modulation seen in the LV after 2 wk persisted in the chronic phase (after 6 and 12 mo) and found that it did persist. Knowing that the adrenergic and renin-angiotensin systems are overactivated in our animal model, we were interested to see if blocking those systems using metoprolol (25 mg.kg(-1).day(-1)) and captopril (100 mg.kg(-1).day(-1)) would alter the expression of some upregulated LV genes in AR rats after 6 mo. By qRT-PCR, we observed that upregulations of LV mRNA levels encoding for procollagens type I and III, fibronectin, atrial natriuretic peptide, transforming growth factor-beta(2), and connective tissue growth factor were totally or partially reversed by this treatment. These observations provide a molecular rationale for a medical strategy aiming these systems in the medical treatment of AR and expand the paradigm in the study of this form of LV volume overload.
Asunto(s)
Antagonistas Adrenérgicos beta/farmacología , Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Insuficiencia de la Válvula Aórtica/tratamiento farmacológico , Perfilación de la Expresión Génica , Hipertrofia Ventricular Izquierda/tratamiento farmacológico , Receptores Adrenérgicos beta/efectos de los fármacos , Sistema Renina-Angiotensina/efectos de los fármacos , Enfermedad Aguda , Animales , Insuficiencia de la Válvula Aórtica/complicaciones , Insuficiencia de la Válvula Aórtica/genética , Insuficiencia de la Válvula Aórtica/metabolismo , Captopril/farmacología , Modelos Animales de Enfermedad , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , Perfilación de la Expresión Génica/métodos , Regulación de la Expresión Génica/efectos de los fármacos , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Hipertrofia Ventricular Izquierda/genética , Hipertrofia Ventricular Izquierda/metabolismo , Masculino , Metoprolol/farmacología , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Receptores Adrenérgicos beta/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Índice de Severidad de la Enfermedad , Factores de TiempoRESUMEN
BACKGROUND AND AIM OF THE STUDY: Chronic aortic regurgitation (AR) induces left ventricular (LV) hypertrophy and eventually LV dysfunction. While the effects of chronic AR on the left ventricle are well known, the effects of acute AR have not been adequately evaluated. It was hypothesized that the LV tissues would be rapidly remodeled by acute AR, and that the renin-angiotensin system would be involved in that acute remodeling. METHOD: The early LV adaptations to acute AR were evaluated serially over a period of 14 days, using a rat model. Adaptations were evaluated in vivo by echocardiography, and in vitro on explanted heart tissue after one, two, or 14 days. RESULTS: After 14 days, the left ventricle of AR rats was already significantly hypertrophied and dilated (end-diastolic diameter +16% (p <0.05) versus sham; LV mass +16% (p <0.01) versus sham). A short and transient increase in fractional shortening was observed during the first 48 h after AR induction. The cardiomyocyte cross-sectional area and perivascular fibrosis were significantly increased after 14 days of AR. The number of fibronectin-positive cells in LV sections rapidly increased, as did the fibronectin protein and mRNA content of LV crude homogenates. The expression of pro-matrix metalloproteinase 2 was clearly abnormal after two days. Significant shifts in the expression of angiotensin II receptors were also detected as early as one 1 day. CONCLUSION: Significant macroscopic and microscopic abnormalities were present in the left ventricle of rats with acute AR, soon after its induction. Considerable hypertrophy, perivascular fibrosis and extracellular matrix (ECM) remodeling were present after only 14 days. These results suggest that, in AR, the myocytes and ECM are affected significantly at a very early stage of the disease.
Asunto(s)
Insuficiencia de la Válvula Aórtica/complicaciones , Insuficiencia de la Válvula Aórtica/fisiopatología , Modelos Animales de Enfermedad , Hipertrofia Ventricular Izquierda/etiología , Hipertrofia Ventricular Izquierda/fisiopatología , Remodelación Ventricular , Enfermedad Aguda , Animales , Insuficiencia de la Válvula Aórtica/metabolismo , Presión Sanguínea/fisiología , Citocinas/metabolismo , Matriz Extracelular/metabolismo , Fibronectinas/metabolismo , Frecuencia Cardíaca/fisiología , Hipertrofia Ventricular Izquierda/metabolismo , Masculino , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Peptidil-Dipeptidasa A/metabolismo , Ratas , Ratas Wistar , Receptores de Angiotensina/metabolismo , Sistema Renina-Angiotensina/fisiología , Factor de Transcripción STAT3/metabolismoRESUMEN
The objective of this study was to assess the long-term effects of beta-blockade on survival and left ventricular (LV) remodeling in rats with aortic valve regurgitation (AR). The pharmacological management of chronic AR remains controversial. No drug has been definitively proven to delay the need for valve replacement or to affect morbidity and/or mortality. Our group has reported that the adrenergic system is activated in an animal model of AR and that adrenergic blockade may help maintain normal LV function. The effects of prolonged treatment with a beta-blocker are unknown. Forty Wistar rats with severe AR were divided into 2 groups of 20 animals each and treated with metoprolol (Met, 25 mg.kg(-1).day(-1)) or left untreated for 1 yr. LV remodeling was evaluated by echocardiography. Survival was assessed by Kaplan-Meir curves. Hearts were harvested for tissue analysis. All Met-treated animals were alive after 6 mo vs. 70% of untreated animals. After 1 yr, 60% of Met-treated animals were alive vs. 35% of untreated animals (P = 0.028). All deaths, except one, were sudden. There were no differences in LV ejection fraction (all >50%) or LV dimensions. LV mass tended to be lower in the Met-treated group. There was less subendocardial fibrosis in this group, as well as lower LV filling pressures (LV end-diastolic pressure). beta-Adrenergic receptor ratio (beta(1)/beta(2)) was improved. One year of treatment with Met was well tolerated. Met improved 1-yr survival, minimized LV hypertrophy, improved LV filling pressures, decreased LV subendocardial fibrosis, and helped restore the beta-adrenergic receptor ratio.
Asunto(s)
Antagonistas de Receptores Adrenérgicos beta 1 , Antagonistas de Receptores Adrenérgicos beta 2 , Antagonistas Adrenérgicos beta/farmacología , Insuficiencia de la Válvula Aórtica/tratamiento farmacológico , Metoprolol/farmacología , Miocardio/metabolismo , Remodelación Ventricular/efectos de los fármacos , Antagonistas Adrenérgicos beta/uso terapéutico , Animales , Insuficiencia de la Válvula Aórtica/metabolismo , Insuficiencia de la Válvula Aórtica/patología , Insuficiencia de la Válvula Aórtica/fisiopatología , Enfermedad Crónica , Modelos Animales de Enfermedad , Ecocardiografía Doppler , Fibrosis , Hemodinámica/efectos de los fármacos , Hipertrofia Ventricular Izquierda/metabolismo , Hipertrofia Ventricular Izquierda/fisiopatología , Hipertrofia Ventricular Izquierda/prevención & control , Masculino , Metoprolol/uso terapéutico , Miocardio/patología , Cadenas Pesadas de Miosina/genética , Cadenas Pesadas de Miosina/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Receptores Adrenérgicos beta 1/genética , Receptores Adrenérgicos beta 1/metabolismo , Receptores Adrenérgicos beta 2/genética , Receptores Adrenérgicos beta 2/metabolismo , Índice de Severidad de la Enfermedad , Volumen Sistólico/efectos de los fármacos , Factores de Tiempo , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
The early events leading to the establishment of left ventricular hypertrophy associated to pressure overload (PO) are not well characterized. To explore these early events, aortic banding (AB) was performed in rats to induce left ventricle (LV) PO. Animals were sacrificed after 24, 48 h or 14 days. An echocardiogram was performed before the procedure and at sacrifice. LVs were preserved for the evaluation of fibrosis, angiotensin II (AT) receptors expression and stress-related MAP kinases (ERK 1/2, JNK and p38) pathways. We observed that concentric LV hypertrophy was established after only 14 days. Collagen I and fibronectin gene expressions were decreased the first 2 days after AB induction whereas AT receptors mRNA levels were sharply increased. ERK 1/2 and JNK activities in LV homogenates were decreased 24 h after AB but came back to normal after 14 days. p38 activity however was stable during the period studied. We also evaluated the presence of two phosphorylated transcription factors related to JNK signaling pathway (ATF-2 and c-Jun) in cardiomyocyte nuclei. The proportion of LV cell nuclei positive for these two activated transcription factors was significantly reduced in AB rats compared to sham. These results suggest that the early response of the LV to acute PO is to attenuate the expression of some pro-fibrotic and pro-hypertrophic signaling pathways and possibly AT signaling by decreasing ERK 1/2 and JNK relative activities.