RESUMO
The endothelial-mesenchymal transition (EndMT) plays a key role in the development of cardiac fibrosis (CF) after acute myocardial infarction (AMI). The results of our previous study showed that amphiregulin (AR) expression was enhanced after MI. However, the role of AR on EndMT post MI remains unknown. This study aimed to elucidate the impact of AR on EndMT post MI and the associated molecular mechanisms. AR expression was markedly enhanced in infarct border area post MI, and endothelial cells were one of the primary cell sources of AR secretion. Stimulation with AR promoted endothelial cell proliferation, invasion, migration, collagen synthesis and EndMT. In addition, EGFR and downstream gene expression was significantly enhanced. In vivo, EndMT was significantly inhibited after lentivirus-AR-shRNA was delivered to the myocardium post MI. In addition, silencing AR ameliorated cardiac function by decreasing the extent of CF. Furthermore, the levels of EGFR pathway components in endothelial cells extracted from infarct border myocardium were all significantly decreased in lentivirus-AR-shRNA-treated MI mice. Our results demonstrate that AR induces CF post MI by enhancing EndMT in endothelial cells. Thus, targeting the regulation of AR may provide a potentially novel therapeutic option for CF after MI.
Assuntos
Anfirregulina/genética , Células Endoteliais/metabolismo , Transição Epitelial-Mesenquimal/genética , Receptores ErbB/genética , Infarto do Miocárdio/genética , Miocárdio/metabolismo , Actinas/genética , Actinas/metabolismo , Anfirregulina/metabolismo , Animais , Caderinas/genética , Caderinas/metabolismo , Sobrevivência Celular , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Colágeno Tipo III , Vasos Coronários/cirurgia , Modelos Animais de Doenças , Fibrose Endomiocárdica , Células Endoteliais/patologia , Receptores ErbB/metabolismo , Regulação da Expressão Gênica , Células Endoteliais da Veia Umbilical Humana , Humanos , Ligadura , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Miocárdio/patologia , Protocaderinas , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Vimentina/genética , Vimentina/metabolismoRESUMO
Cardiac fibrosis (CF), a main process of ventricular remodeling after myocardial infarction (MI), plays a crucial role in the pathogenesis of heart failure (HF) post-MI. It is known that amphiregulin (AR) is involved in fibrosis of several organs. However, the expression of AR and its role post-MI are yet to be determined. This study aimed to investigate the impact of AR on CF post-MI and related mechanisms. Significantly upregulated AR expression was evidenced in the infarct border zone of MI mice in vivo and the AR secretion was enhanced in macrophages, but not in cardiac fibroblasts. In vitro, treatment with AR increased cardiac fibroblast migration, proliferation and collagen synthesis, and upregulated the expression of epidermal growth factor receptor (EGFR) and the downstream genes such as Akt, ERK1/2 and Samd2/3 on cardiac fibroblasts. All these effects could be abrogated by pretreatment with a specific EGFR inhibitor. To verify the functions of AR in MI hearts, lentivirus-AR-shRNA and negative control vectors were delivered into the infarct border zone. After 28 days, knock-down of AR increased the survival rate and improved cardiac function, while decreasing the extent of myocardial fibrosis of MI mice. Moreover, EGFR and the downstream genes were significantly downregulated in lentivirus-AR-shRNA treated MI mice. Our results thus indicate that AR plays an important role in promoting CF after MI partly though activating the EGFR pathway. Targeting AR might be a novel therapeutic option for attenuating CF and improve cardiac function after MI.
Assuntos
Anfirregulina/metabolismo , Receptores ErbB/metabolismo , Infarto do Miocárdio/metabolismo , Miocárdio/metabolismo , Função Ventricular Esquerda , Remodelação Ventricular , Anfirregulina/genética , Animais , Movimento Celular , Proliferação de Células , Células Cultivadas , Colágeno/metabolismo , Modelos Animais de Doenças , Receptores ErbB/genética , Fibroblastos/metabolismo , Fibroblastos/patologia , Fibrose , Macrófagos/metabolismo , Macrófagos/patologia , Masculino , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/genética , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Miocárdio/patologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Interferência de RNA , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Função Ventricular Esquerda/genética , Remodelação Ventricular/genéticaRESUMO
BACKGROUND/AIMS: Reperfusion after an ischaemic insult might cause infarct extension. Mesenchymal stem cell (MSC)-derived exosomes could attenuate myocardial remodelling in animal models of myocardial ischaemia reperfusion injury (MIRI), and the present study aimed to explore the related mechanisms. METHODS: In vitro, rat H9C2 cardiomyocytes (H9C2s) were exposed to H2O2. Cell viability was detected by the CCK-8 assay, apoptosis was detected by Annexin V-PE/7-AAD staining, ROS production was detected by fluorescence microscopy and flow cytometry, and apoptosis-related proteins and signalling pathway-related proteins were detected by western blot analysis. Autophagic flux was measured using the tandem fluorescent mRFG-GFP-LC3 assay. MSC-derived exosomes were extracted using the total exosome isolation reagent. Apoptosis, myocardial infarction size, heart function and myocardial LC3B expression were examined in an in vivo I/R model by the TUNEL assay, TTC/Evan blue staining, echocardiography and immunohistochemicalstaining, respectively. RESULTS: In vitro, H2O2 dose-dependently increased ROS production and cell apoptosis in H9C2s and blocked autophagic flux after 3 h of exposure; autophagy gradually decreased thereafter, and the lowest level was detected at 12 h after exposure. MSC-derived exosomes reduced H2O2-induced ROS production and cell apoptosis and enhanced autophagy at 12 h after exposure. In H9C2 cells exposed to H2O2 for 12 h, treatment with exosomes enhanced autophagy via the AMPK/mTOR and Akt/mTOR pathways. Likewise, in vivo exosome injections in rats that underwent I/R injury significantly reduced apoptosis and the myocardial infarct size and upregulated myocardial LC3B expression as well as improved heart function. CONCLUSIONS: Our results indicate that MSC-derived exosomes could reduce MIRI by inducing cardiomyocyte autophagy via AMPK/mTOR and Akt/mTOR pathways.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Autofagia , Exossomos/fisiologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Células da Medula Óssea/citologia , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Modelos Animais de Doenças , Coração/diagnóstico por imagem , Peróxido de Hidrogênio/toxicidade , Masculino , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miócitos Cardíacos/citologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
BACKGROUND: Prior work has identified age, body mass index, underlying heart disease, and other comorbidities as risk factors for atrial fibrillation. To date, studies have examined single baseline measures of traditional risk factors, and data on biomarker associations are lacking. OBJECTIVE: We sought to explore novel biochemical measures possibly associated with incident PAF after balancing the traditional risk factors. METHODS: Men or women aged ≥18 years that were hospitalized between 1(st) Jan. 2010 and 31(st) Dec. 2013 for paroxysmal atrial fibrillation (PAF) and for health checkup (non-PAF) were included. We used propensity score methods to mitigate the influence of the nonrandom selection of PAF and non-PAF patients. Logistic regression was applied for analysis of risk factors for PAF. RESULTS: A total of 1,802 eligible patients were identified, in whom, 895 patients had at least one exclusion criterion. After excluding these patients, the total analytic cohort numbered 907 patients. Of these, 779 patients were for control group and 128 patients were for PAF group. Propensity score matching was used to obtain a balanced cohort of 124 patients per group. The PAF and non-PAF groups were well matched on demographic and clinical characteristics after propensity matching. Risk factors for PAF on multivariate stepwise logistic regression model included adenosine deaminase (ADA) [odds ratio (OR) =0.9160, P=0.015, 95% confidence interval (CI): 0.8536-0.9829], mitral valvular regurgitation (OR =3.4611, P=0.001, 95% CI: 1.7000-7.0467) and left atrial diameter (OR =1.0913, P=0.001, 95% CI: 1.0387-1.1465). Only the ADA was a protective factor for the occurrence of PAF. CONCLUSIONS: The ADA seems to be associated with PAF. The current study provides new insights into the prevention and treatment of PAF.