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BACKGROUND: Atrial fibrillation has an estimated prevalence of 1.5-2%, making it the most common cardiac arrhythmia. The processes that cause and sustain the disease are still not completely understood. An association between atrial fibrillation and systemic, as well as local, inflammatory processes has been reported. However, the exact mechanisms underlying this association have not been established. While it is understood that inflammatory macrophages can influence cardiac electrophysiology, a direct, causative relationship to atrial fibrillation has not been described. This study investigated the pro-arrhythmic effects of activated M1 macrophages on human induced pluripotent stem cell (hiPSC)-derived atrial cardiomyocytes, to propose a mechanistic link between inflammation and atrial fibrillation. METHODS: Two hiPSC lines from healthy individuals were differentiated to atrial cardiomyocytes and M1 macrophages and integrated in an isogenic, pacing-free, atrial fibrillation-like coculture model. Electrophysiology characteristics of cocultures were analysed for beat rate irregularity, electrogram amplitude and conduction velocity using multi electrode arrays. Cocultures were additionally treated using glucocorticoids to suppress M1 inflammation. Bulk RNA sequencing was performed on coculture-isolated atrial cardiomyocytes and compared to meta-analyses of atrial fibrillation patient transcriptomes. RESULTS: Multi electrode array recordings revealed M1 to cause irregular beating and reduced electrogram amplitude. Conduction analysis further showed significantly lowered conduction homogeneity in M1 cocultures. Transcriptome sequencing revealed reduced expression of key cardiac genes such as SCN5A, KCNA5, ATP1A1, and GJA5 in the atrial cardiomyocytes. Meta-analysis of atrial fibrillation patient transcriptomes showed high correlation to the in vitro model. Treatment of the coculture with glucocorticoids showed reversal of phenotypes, including reduced beat irregularity, improved conduction, and reversed RNA expression profiles. CONCLUSIONS: This study establishes a causal relationship between M1 activation and the development of subsequent atrial arrhythmia, documented as irregularity in spontaneous electrical activation in atrial cardiomyocytes cocultured with activated macrophages. Further, beat rate irregularity could be alleviated using glucocorticoids. Overall, these results point at macrophage-mediated inflammation as a potential AF induction mechanism and offer new targets for therapeutic development. The findings strongly support the relevance of the proposed hiPSC-derived coculture model and present it as a first of its kind disease model.
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Fibrilación Atrial , Técnicas de Cocultivo , Células Madre Pluripotentes Inducidas , Macrófagos , Miocitos Cardíacos , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Células Madre Pluripotentes Inducidas/citología , Miocitos Cardíacos/metabolismo , Fibrilación Atrial/metabolismo , Fibrilación Atrial/patología , Macrófagos/metabolismo , Fenotipo , Diferenciación Celular , Atrios Cardíacos/patología , Atrios Cardíacos/metabolismo , Atrios Cardíacos/citologíaRESUMEN
Atrial fibrillation (AF) is the most common sustained arrhythmia and carries an increased risk of stroke and heart failure. Here we investigated how the immune infiltrate of human epicardial adipose tissue (EAT), which directly overlies the myocardium, contributes to AF. Flow cytometry analysis revealed an enrichment of tissue-resident memory T (TRM) cells in patients with AF. Cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) and single-cell T cell receptor (TCR) sequencing identified two transcriptionally distinct CD8+ TRM cells that are modulated in AF. Spatial transcriptomic analysis of EAT and atrial tissue identified the border region between the tissues to be a region of intense inflammatory and fibrotic activity, and the addition of TRM populations to atrial cardiomyocytes demonstrated their ability to differentially alter calcium flux as well as activate inflammatory and apoptotic signaling pathways. This study identified EAT as a reservoir of TRM cells that can directly modulate vulnerability to cardiac arrhythmia.
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Tejido Adiposo , Fibrilación Atrial , Células T de Memoria , Pericardio , Fibrilación Atrial/inmunología , Fibrilación Atrial/genética , Fibrilación Atrial/patología , Fibrilación Atrial/metabolismo , Humanos , Pericardio/metabolismo , Pericardio/patología , Pericardio/inmunología , Tejido Adiposo/metabolismo , Tejido Adiposo/inmunología , Tejido Adiposo/patología , Células T de Memoria/inmunología , Células T de Memoria/metabolismo , Masculino , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Transcriptoma , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Miocitos Cardíacos/inmunología , Femenino , Persona de Mediana Edad , Perfilación de la Expresión Génica , Anciano , Fenotipo , Señalización del Calcio , Apoptosis , Memoria Inmunológica , Transcripción Genética , Estudios de Casos y Controles , Atrios Cardíacos/patología , Atrios Cardíacos/inmunología , Atrios Cardíacos/metabolismo , Fibrosis/patología , Tejido Adiposo EpicárdicoRESUMEN
BACKGROUND: Doxorubicin is an important anticancer drug, however, elicits dose-dependently cardiomyopathy. Given its mode of action, i.e. topoisomerase inhibition and DNA damage, we investigated genetic events associated with cardiomyopathy and searched for mechanism-based possibilities to alleviate cardiotoxicity. We treated rats at clinically relevant doses of doxorubicin. Histopathology and transmission electron microscopy (TEM) defined cardiac lesions, and transcriptomics unveiled cardiomyopathy-associated gene regulations. Genomic-footprints revealed critical components of Abl1-p53-signaling, and EMSA-assays evidenced Abl1 DNA-binding activity. Gene reporter assays confirmed Abl1 activity on p53-targets while immunohistochemistry/immunofluorescence microscopy demonstrated Abl1, p53&p73 signaling. RESULTS: Doxorubicin treatment caused dose-dependently toxic cardiomyopathy, and TEM evidenced damaged mitochondria and myofibrillar disarray. Surviving cardiomyocytes repressed Parkin-1 and Bnip3-mediated mitophagy, stimulated dynamin-1-like dependent mitochondrial fission and induced anti-apoptotic Bag1 signaling. Thus, we observed induced mitochondrial biogenesis. Transcriptomics discovered heterogeneity in cellular responses with minimal overlap between treatments, and the data are highly suggestive for distinct cardiomyocyte (sub)populations which differed in their resilience and reparative capacity. Genome-wide footprints revealed Abl1 and p53 enriched binding sites in doxorubicin-regulated genes, and we confirmed Abl1 DNA-binding activity in EMSA-assays. Extraordinarily, Abl1 signaling differed in the heart with highly significant regulations of Abl1, p53 and p73 in atrial cardiomyocytes. Conversely, in ventricular cardiomyocytes, Abl1 solely-modulated p53-signaling that was BAX transcription-independent. Gene reporter assays established Abl1 cofactor activity for the p53-reporter PG13-luc, and ectopic Abl1 expression stimulated p53-mediated apoptosis. CONCLUSIONS: The tyrosine kinase Abl1 is of critical importance in doxorubicin induced cardiomyopathy, and we propose its inhibition as means to diminish risk of cardiotoxicity.
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Cardiomiopatías , Doxorrubicina , Miocitos Cardíacos , Proteínas Proto-Oncogénicas c-abl , Transducción de Señal , Proteína p53 Supresora de Tumor , Animales , Doxorrubicina/efectos adversos , Doxorrubicina/farmacología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Proteína p53 Supresora de Tumor/metabolismo , Transducción de Señal/efectos de los fármacos , Cardiomiopatías/inducido químicamente , Cardiomiopatías/patología , Cardiomiopatías/metabolismo , Proteínas Proto-Oncogénicas c-abl/metabolismo , Proteínas Proto-Oncogénicas c-abl/genética , Ventrículos Cardíacos/patología , Ventrículos Cardíacos/efectos de los fármacos , Atrios Cardíacos/patología , Atrios Cardíacos/efectos de los fármacos , Atrios Cardíacos/metabolismo , Muerte Celular/efectos de los fármacos , Masculino , Ratas , Ratas WistarRESUMEN
Catheter ablation (CA) is an essential method for the interventional treatment of atrial fibrillation (AF), and it is very important to reduce long-term recurrence after CA. The mechanism of recurrence after CA is still unclear. We established a long-term model of beagle canines after circumferential pulmonary vein ablation (CPVA). The transcriptome and proteome were obtained using high-throughput sequencing and TMT-tagged LC-MS/LC analysis, respectively. Differentially expressed genes and proteins were screened and enriched, and the effect of fibrosis was found and verified in tissues. A downregulated protein, neuropeptide Y (NPY), was selected for validation and the results suggest that NPY may play a role in the long-term reinduction of AF after CPVA. Then, the molecular mechanism of NPY was further investigated. The results showed that the atrial effective refractory period (AERP) was shortened and fibrosis was increased after CPVA. Atrial myocyte apoptosis was alleviated by NPY intervention, and Akt activation was inhibited in cardiac fibroblasts. These results suggest that long-term suppression of NPY after CPVA may lead to induction of AF through promoting cardiomyocyte apoptosis and activating the Akt pathway in cardiac fibroblasts, which may make AF more likely to reinduce.
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Apoptosis , Fibrilación Atrial , Ablación por Catéter , Miocardio , Neuropéptido Y , Venas Pulmonares , Animales , Perros , Apoptosis/efectos de los fármacos , Fibrilación Atrial/metabolismo , Fibrilación Atrial/cirugía , Fibrilación Atrial/patología , Ablación por Catéter/métodos , Modelos Animales de Enfermedad , Fibrosis , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Multiómica , Miocardio/metabolismo , Miocardio/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/patología , Neuropéptido Y/metabolismo , Proteoma/metabolismo , Proteómica/métodos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Venas Pulmonares/metabolismo , Venas Pulmonares/cirugía , TranscriptomaRESUMEN
Left-to-right differences in the histopathologic patterns of transthyretin-derived amyloid (ATTR) deposition in the atria of older adults have not yet been investigated. Hence, this study evaluated heart specimens from 325 serial autopsy subjects. The amount of ATTR deposits in the seven cardiac regions, including both sides of atria and atrial appendages, was evaluated semiquantitatively. Using digital pathology, we quantitatively evaluated the immunohistochemical deposition burden of ATTR in the myocardium. We identified 20 sporadic ATTR cardiac amyloidosis cases (nine males). All patients had ATTR deposition in the left atrial regions of the myocardium. In the semiquantitative analysis, 14 of the 20 cases showed more severe ATTR deposition on the left atrial regions than on the right side, with statistically significant differences in the pathology grading (p < 0.01 for both the atrium and atrial appendage). Quantitative analysis further supported the difference. Moreover, six had ATTR deposition in the epineurium and/or neural fibers of the atria. Cluster analysis revealed that ATTR deposition in the myocardium was significantly more severe in males than in females. The heterogeneous distribution of amyloid deposits between atria revealed in this study may impair the orderly transmission of the cardiac conduction system and induce arrhythmias, which may be further aggravated by additional neuropathy in the advanced phase. This impairment could be more severe among males. These findings emphasize that atrial evaluation is important for individuals with sporadic ATTR cardiac amyloidosis, particularly for early detection.
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Autopsia , Atrios Cardíacos , Prealbúmina , Humanos , Masculino , Femenino , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Anciano , Anciano de 80 o más Años , Prealbúmina/metabolismo , Persona de Mediana Edad , Miocardio/metabolismo , Miocardio/patología , Neuropatías Amiloides Familiares/metabolismo , Neuropatías Amiloides Familiares/patología , Amiloide/metabolismo , Amiloidosis/metabolismo , Amiloidosis/patologíaRESUMEN
ABSTRACT: Previous studies have found that anxiety disorders may increase the incidence of atrial fibrillation (AF). More and more studies have shown that α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are involved in the occurrence and development of cardiovascular diseases. However, the role of AMPARs in AF associated with anxiety disorder remains unclear. The aim of this study was to investigate the effect of AMPARs on AF susceptibility in rats with anxiety disorder and its possible mechanism. The anxiety disorder rat model was established by unpredictable empty bottle stimulation and was treated with AMPARs agonist and antagonist. Our results showed that AMPARs antagonist treatment significantly reduced sympathetic activity, improved heart rate variability, shortened action potential duration, prolonged effective refractory period, reduced AF induction rate, and improved cardiac electrical remodeling and the expression of inflammatory factors. In addition, inhibition of AMPARs reduced the phosphorylation of IκBα and p65. Our experimental results suggest that inhibition of AMPARs can reduce autonomic remodeling, improve atrial electrical remodeling, and suppress myocardial inflammation, which provides a potential therapeutic strategy for the treatment of AF associated with anxiety disorder.
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Trastornos de Ansiedad , Fibrilación Atrial , Modelos Animales de Enfermedad , Atrios Cardíacos , Ratas Sprague-Dawley , Receptores AMPA , Animales , Fibrilación Atrial/fisiopatología , Fibrilación Atrial/tratamiento farmacológico , Fibrilación Atrial/metabolismo , Masculino , Trastornos de Ansiedad/tratamiento farmacológico , Trastornos de Ansiedad/metabolismo , Trastornos de Ansiedad/fisiopatología , Atrios Cardíacos/efectos de los fármacos , Atrios Cardíacos/fisiopatología , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Receptores AMPA/metabolismo , Remodelación Atrial/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Mediadores de Inflamación/metabolismo , Potenciales de Acción/efectos de los fármacos , Fosforilación , Transducción de Señal , Sistema Nervioso Simpático/fisiopatología , Sistema Nervioso Simpático/efectos de los fármacos , Sistema Nervioso Simpático/metabolismo , Factor de Transcripción ReIA/metabolismo , Ratas , Antiinflamatorios/farmacología , Periodo Refractario Electrofisiológico/efectos de los fármacos , Inhibidor NF-kappaB alfa/metabolismoRESUMEN
BACKGROUND: Atrial cardiomyopathy (ACM) is responsible for atrial fibrillation (AF) and thromboembolic events. Diabetes mellitus (DM) is an important risk factor for ACM. However, the potential mechanism between ACM and DM remains elusive. METHODS: Atrial tissue samples were obtained from patients diagnosed with AF or sinus rhythm (SR) to assess alterations in NR4A3 expression, and then two distinct animal models were generated by subjecting Nr4a3-/- mice and WT mice to a high-fat diet (HFD) and Streptozotocin (STZ), while db/db mice were administered AAV9-Nr4a3 or AAV9-ctrl. Subsequently, in vivo and in vitro experiments were conducted to assess the impact of NR4A3 on diabetes-induced atrial remodeling through electrophysiological, biological, and histological analyses. RNA sequencing (RNA-seq) and metabolomics analysis were employed to unravel the downstream mechanisms. FINDINGS: The expression of NR4A3 was significantly decreased in atrial tissues of both AF patients and diabetic mice compared to their respective control groups. NR4A3 deficiency exacerbated atrial hypertrophy and atrial fibrosis, and increased susceptibility to pacing-induced AF. Conversely, overexpression of NR4A3 alleviated atrial structural remodeling and reduced AF induction rate. Mechanistically, we confirmed that NR4A3 improves mitochondrial energy metabolism and reduces oxidative stress injury by preserving the transcriptional expression of Sdha, thereby exerting a protective influence on atrial remodeling induced by diabetes. INTERPRETATION: Our data confirm that NR4A3 plays a protective role in atrial remodeling caused by diabetes, so it may be a new target for treating ACM. FUNDING: This study was supported by the major research program of National Natural Science Foundation of China (NSFC) No: 82370316 (to Q-S. W.), No. 81974041 (to Y-P. W.), and No. 82270447 (to Y-P. W.) and Fundation of Shanghai Hospital Development Center (No. SHDC2022CRD044 to Q-S. W.).
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Diabetes Mellitus Experimental , Metabolismo Energético , Estrés Oxidativo , Animales , Ratones , Humanos , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/complicaciones , Masculino , Ratones Noqueados , Receptores de Hormona Tiroidea/metabolismo , Receptores de Hormona Tiroidea/genética , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Fibrilación Atrial/metabolismo , Fibrilación Atrial/etiología , Fibrilación Atrial/prevención & control , Modelos Animales de Enfermedad , Mitocondrias/metabolismo , Cardiomiopatías Diabéticas/metabolismo , Cardiomiopatías Diabéticas/etiología , Cardiomiopatías Diabéticas/genética , Cardiomiopatías Diabéticas/patología , Cardiomiopatías Diabéticas/prevención & control , Cardiomiopatías/etiología , Cardiomiopatías/metabolismo , Remodelación Atrial , Proteínas de Unión al ADN , Receptores de EsteroidesRESUMEN
Atrial fibrosis is associated with the occurrence of atrial fibrillation (AF) and regulated by the transforming growth factor-ß1 (TGF-ß1)/Smad2/3 signalling pathway. Unfortunately, the mechanisms of regulation of TGF-ß1/Smad2/3-induced atrial fibrosis and vulnerability to AF remain still unknown. Previous studies have shown that sirtuin3 (SIRT3) sulfhydration has strong anti-fibrotic effects. We hypothesised that SIRT3 sulfhydration inhibits angiotensin II (Ang-II)-induced atrial fibrosis via blocking the TGF-ß1/Smad2/3 signalling pathway. In this study, we found that SIRT3 expression was decreased in the left atrium of patients with AF compared to that in those with sinus rhythm (SR). In vitro, SIRT3 knockdown by small interfering RNA significantly expanded Ang-II-induced atrial fibrosis and TGF-ß1/Smad2/3 signalling pathway activation, whereas supplementation with Sodium Hydrosulfide (NaHS, exogenous hydrogen sulfide donor and sulfhydration agonist) and SIRT3 overexpression using adenovirus ameliorated Ang-II-induced atrial fibrosis. Moreover, we observed suppression of the TGF-ß1/Smad2/3 pathway when Ang-II was combined with NaHS treatment, and the effect of this co-treatment was consistent with that of Ang-II combined with LY3200882 (Smad pathway inhibitor) on reducing atrial fibroblast proliferation and cell migration in vitro. Supplementation with dithiothreitol (DTT, a sulfhydration inhibitor) and adenovirus SIRT3 shRNA blocked the ameliorating effect of NaHS and AngII co-treatment on atrial fibrosis in vitro. Finally, continued treatment with NaHS in rats ameliorated atrial fibrosis and remodelling, and further improved AF vulnerability induced by Ang-II, which was reversed by DTT and adenovirus SIRT3 shRNA, suggesting that SIRT3 sulfhydration might be a potential therapeutic target in atrial fibrosis and AF.
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Angiotensina II , Fibrilación Atrial , Fibrosis , Atrios Cardíacos , Sulfuro de Hidrógeno , Transducción de Señal , Sirtuina 3 , Proteína Smad2 , Proteína smad3 , Factor de Crecimiento Transformador beta1 , Angiotensina II/farmacología , Sirtuina 3/metabolismo , Sirtuina 3/genética , Fibrilación Atrial/metabolismo , Fibrilación Atrial/patología , Fibrilación Atrial/prevención & control , Factor de Crecimiento Transformador beta1/metabolismo , Transducción de Señal/efectos de los fármacos , Proteína smad3/metabolismo , Animales , Proteína Smad2/metabolismo , Atrios Cardíacos/efectos de los fármacos , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Sulfuro de Hidrógeno/farmacología , Sulfuro de Hidrógeno/metabolismo , Masculino , Humanos , Ratas , Ratas Sprague-Dawley , Femenino , Persona de Mediana Edad , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacosRESUMEN
BACKGROUND: Transverse (t)-tubules drive the rapid and synchronous Ca2+ rise in cardiac myocytes. The virtual complete atrial t-tubule loss in heart failure (HF) decreases Ca2+ release. It is unknown if or how atrial t-tubules can be restored and how this affects systolic Ca2+. METHODS: HF was induced in sheep by rapid ventricular pacing and recovered following termination of rapid pacing. Serial block-face scanning electron microscopy and confocal imaging were used to study t-tubule ultrastructure. Function was assessed using patch clamp, Ca2+, and confocal imaging. Candidate proteins involved in atrial t-tubule recovery were identified by western blot and expressed in rat neonatal ventricular myocytes to determine if they altered t-tubule structure. RESULTS: Atrial t-tubules were lost in HF but reappeared following recovery from HF. Recovered t-tubules were disordered, adopting distinct morphologies with increased t-tubule length and branching. T-tubule disorder was associated with mitochondrial disorder. Recovered t-tubules were functional, triggering Ca2+ release in the cell interior. Systolic Ca2+, ICa-L, sarcoplasmic reticulum Ca2+ content, and sarcoendoplasmic reticulum Ca2+ ATPase function were restored following recovery from HF. Confocal microscopy showed fragmentation of ryanodine receptor staining and movement away from the z-line in HF, which was reversed following recovery from HF. Acute detubulation, to remove recovered t-tubules, confirmed their key role in restoration of the systolic Ca2+ transient, the rate of Ca2+ removal, and the peak L-type Ca2+ current. The abundance of telethonin and myotubularin decreased during HF and increased during recovery. Transfection with these proteins altered the density and structure of tubules in neonatal myocytes. Myotubularin had a greater effect, increasing tubule length and branching, replicating that seen in the recovery atria. CONCLUSIONS: We show that recovery from HF restores atrial t-tubules, and this promotes recovery of ICa-L, sarcoplasmic reticulum Ca2+ content, and systolic Ca2+. We demonstrate an important role for myotubularin in t-tubule restoration. Our findings reveal a new and viable therapeutic strategy.
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Atrios Cardíacos , Insuficiencia Cardíaca , Miocitos Cardíacos , Animales , Insuficiencia Cardíaca/metabolismo , Insuficiencia Cardíaca/fisiopatología , Insuficiencia Cardíaca/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Miocitos Cardíacos/ultraestructura , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Atrios Cardíacos/fisiopatología , Ovinos , Calcio/metabolismo , Señalización del Calcio , Ratas , Retículo Sarcoplasmático/metabolismo , Retículo Sarcoplasmático/ultraestructura , Retículo Sarcoplasmático/patología , Recuperación de la Función , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Mitocondrias Cardíacas/patología , Células Cultivadas , Sístole , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Ratas Sprague-Dawley , FemeninoRESUMEN
BACKGROUND: Atrial fibrillation (AF) is associated with increased risk of stroke and mortality. It has been reported that the process of atrial fibrosis was regulated by ß-catenin in rats with AF. However, pathophysiological mechanisms of this process in human with AF remain unclear. This study aims to investigate the possible mechanisms of ß-catenin in participating in the atrial fibrosis using human right atrial appendage (hRAA) tissues . METHODS: We compared the difference of ß-catenin expression in hRAA tissues between the patients with AF and sinus rhythm (SR). The possible function of ß-catenin in the development of AF was also explored in mice and primary cells. RESULTS: Firstly, the space between the membrane of the gap junctions of cardiomyocytes was wider in the AF group. Secondly, the expression of the gap junction function related proteins, Connexin40 and Connexin43, was decreased, while the expression of ß-catenin and its binding partner E-cadherin was increased in hRAA and cardiomyocytes of the AF group. Thirdly, ß-catenin colocalized with E-cadherin on the plasma membrane of cardiomyocytes in the SR group, while they were dissociated and accumulated intracellularly in the AF group. Furthermore, the expression of glycogen synthase kinase 3ß (GSK-3ß) and Adenomatous Polyposis Coli (APC), which participated in the degradation of ß-catenin, was decreased in hRAA tissues and cardiomyocytes of the AF group. Finally, the development of atrial fibrosis and AF were proved to be prevented after inhibiting ß-catenin expression in the AF model mice. CONCLUSIONS: Based on human atrial pathological and molecular analyses, our findings provided evidence that ß-catenin was associated with atrial fibrosis and AF progression.
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Fibrilación Atrial , Fibrosis , Atrios Cardíacos , Miocitos Cardíacos , beta Catenina , Anciano , Animales , Femenino , Humanos , Masculino , Ratones , Persona de Mediana Edad , Fibrilación Atrial/patología , Fibrilación Atrial/metabolismo , beta Catenina/metabolismo , Cadherinas/metabolismo , Conexina 43/metabolismo , Uniones Comunicantes/metabolismo , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Ratones Endogámicos C57BL , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patologíaRESUMEN
BACKGROUND: Atrial fibrosis is associated with the pathogenesis of atrial fibrillation (AF). This study aims to discuss the function of circ_0079480 in atrial fibrosis and its underlying mechanism. METHODS: In vitro and in vivo models of atrial fibrosis were established by using angiotensin II (Ang II) to treat human atrial fibroblasts (HAFs) and C57/B6J mice. qRT-PCR and western blot were used to examine the mRNA and protein expression levels. CCK-8, EdU, cell strach, and transwell assays were performed to determine the proliferation and migration of HAFs. Dual-luciferase reporter and RIP/RNA pull-down assays were explored to identify the interaction of miR-338-3p and circ_0079480/THBS1. HE and Masson's trichrome staining experiments were performed to analyze the histopathological change in mice atrial tissues. RESULTS: Circ_0079480 expression was increased in AF patients' atrial tissues and Ang II-treated HAFs. Silencing circ_0079480 inhibited cell proliferation and migration and reduced fibrosis-associated gene expression in Ang II-treated HAFs. Circ_0079480 could target miR-338-3p to repress its expression. MiR-338-3p inhibitor blocked the inhibitory effects of circ_0079480 knockdown on HAFs proliferation, migration, and fibrosis. Thrombospondin-1 (THBS1) was confirmed as a downstream target of miR-338-3p, and circ_0079480 could sponge miR-338-3p to upregulate THBS1 expression. Moreover, silencing THBS1 suppressed Ang II-induced proliferation, migration, and fibrosis in HAFs. More importantly, depletion of circ_0079480 inactivated the THBS1/TGF-ß1/Smad3 signaling by upregulating miR-338-3p. Mice experiments also confirmed the suppression of circ_0079480 knockdown on atrial fibrosis. CONCLUSION: Circ_0079480 acts as a sponge of miR-338-3p to upregulate THBS1 expression and activate the TGF-ß1/Smad3 signaling, finally promoting Ang II-induced atrial fibrosis.
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Fibrilación Atrial , Movimiento Celular , Proliferación Celular , Fibroblastos , Fibrosis , Atrios Cardíacos , Ratones Endogámicos C57BL , MicroARNs , ARN Circular , Transducción de Señal , Proteína smad3 , Trombospondina 1 , Factor de Crecimiento Transformador beta1 , Fibrilación Atrial/genética , Fibrilación Atrial/metabolismo , Fibrilación Atrial/patología , MicroARNs/genética , MicroARNs/metabolismo , Animales , Proteína smad3/metabolismo , Proteína smad3/genética , Ratones , Proliferación Celular/fisiología , Humanos , Factor de Crecimiento Transformador beta1/metabolismo , Trombospondina 1/genética , Trombospondina 1/metabolismo , Trombospondina 1/biosíntesis , Movimiento Celular/fisiología , ARN Circular/genética , ARN Circular/metabolismo , Fibroblastos/metabolismo , Fibroblastos/patología , Atrios Cardíacos/patología , Atrios Cardíacos/metabolismo , Transducción de Señal/fisiología , Masculino , Células CultivadasRESUMEN
BACKGROUND: The biological functions of mitochondrial complexes are closely related to the development of atrial fibrillation (AF). Calcium binding and coiled-coil domain 2 (CALCOCO2) is a novel and specific receptor for mitophagy; however, its function in AF remains unknown. Therefore, this study aimed to investigate the role and molecular mechanisms of CALCOCO2 in AF, especially its regulatory mechanism in mitophagy and mitochondrial stress. METHODS: Mice and HL-1 cells were treated with AngII to establish in vitro and in vivo AF models. Additionally, we examined the effect of CALCOCO2 or DAP3 Binding Cell Death Enhancer 1 (DELE1) overexpression on mitophagy and mitochondrial stress in AF models. To investigate the role of mitophagy in the regulatory effects of CALCOCO2 in AF, HL-1 cells were treated with chloroquine, a mitophagy inhibitor. Moreover, mitochondrial parameters were examined using specific fluorescent probes, transmission electron microscopy, western blotting, immunohistochemistry, and confocal microscopy. RESULTS: AngII severely impaired the normal morphology and function of mitochondria; inhibited mitophagy; promoted atrial mitochondrial stress, fibrosis, and oxidative stress; and accelerated the progression of atrial remodeling in atrial myocytes. However, CALCOCO2 overexpression reversed/ameliorated these AF-induced changes. Additionally, CALCOCO2 overexpression restored mitochondrial homeostasis in atrial muscle by activating mitophagy and ameliorating mitochondrial stress. Mechanistically, DELE1 overexpression increased mitochondrial reactive oxygen species level and the expression of mitochondrial stress proteins (HRI, eIF2α, and ATF4) even in CALCOCO2-expressing in vitro AF models.. CONCLUSIONS: CALCOCO2 may serve as a potential target for AF therapy to prevent or reverse the progression of atrial remodeling by regulating mitophagy and DELE1-mediated mitochondrial stress.
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Angiotensina II , Fibrilación Atrial , Remodelación Atrial , Mitofagia , Animales , Humanos , Masculino , Ratones , Fibrilación Atrial/metabolismo , Proteínas de Unión al Calcio/metabolismo , Proteínas de Unión al Calcio/genética , Línea Celular , Modelos Animales de Enfermedad , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Ratones Endogámicos C57BL , Mitocondrias/metabolismo , Mitofagia/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Estrés OxidativoRESUMEN
The E-twenty-six variant 1 (ETV1)-dependent transcriptome plays an important role in atrial electrical and structural remodelling and the occurrence of atrial fibrillation (AF), but the underlying mechanism of ETV1 in AF is unclear. In this study, cardiomyocyte-specific ETV1 knockout (ETV1f/fMyHCCre/+, ETV1-CKO) mice were constructed to observe the susceptibility to AF and the underlying mechanism in AF associated with ETV1-CKO mice. AF susceptibility was examined by intraesophageal burst pacing, induction of AF was increased obviously in ETV1-CKO mice than WT mice. Electrophysiology experiments indicated shortened APD50 and APD90, increased incidence of DADs, decreased density of ICa,L in ETV1-CKO mice. There was no difference in VINACT,1/2 and VACT,1/2, but a significantly longer duration of the recovery time after inactivation in the ETV1-CKO mice. The recording of intracellular Ca2+ showed that there was significantly increased in the frequency of calcium spark, Ca2+ transient amplitude, and proportion of SCaEs in ETV1-CKO mice. Reduction of Cav1.2 rather than NCX1 and SERCA2a, increase RyR2, p-RyR2 and CaMKII was reflected in ETV1-CKO group. This study demonstrates that the increase in calcium spark and SCaEs corresponding to Ca2+ transient amplitude may trigger DAD in membrane potential in ETV1-CKO mice, thereby increasing the risk of AF.
Asunto(s)
Fibrilación Atrial , Calcio , Atrios Cardíacos , Ratones Noqueados , Miocitos Cardíacos , Factores de Transcripción , Animales , Miocitos Cardíacos/metabolismo , Ratones , Fibrilación Atrial/metabolismo , Fibrilación Atrial/genética , Calcio/metabolismo , Atrios Cardíacos/metabolismo , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Señalización del Calcio , Potenciales de Acción , Potenciales de la Membrana , MasculinoRESUMEN
BACKGROUND: Aging is one of the most potent risk determinants for the onset of atrial fibrillation (AF). Sirts (sirtuins) have been implicated in the pathogenesis of cardiovascular disease, and their expression declines with aging. However, whether Sirts involved in age-related AF and its underlying mechanisms remain unknown. The present study aims to explore the role of Sirts in age-related AF and delineate the underlying molecular mechanisms. METHODS: Sirt1 levels in the atria of both elderly individuals and aging rats were evaluated using quantitative real-time polymerase chain reaction and Western blot analysis. Mice were engineered to specifically knockout Sirt1 in the atria and right ventricle (Sirt1mef2c/mef2c). Various techniques, such as echocardiography, atrial electrophysiology, and protein acetylation modification omics were employed. Additionally, coimmunoprecipitation was utilized to substantiate the interaction between Sirt1 and RIPK1 (receptor-interacting protein kinase 1). RESULTS: We discerned that among the diverse subtypes of sirtuin proteins, only Sirt1 expression was significantly diminished in the atria of elderly people and aged rats. The Sirt1mef2c/mef2c mice exhibited an enlarged atrial diameter and heightened vulnerability to AF. Acetylated proteomics and cell experiments identified that Sirt1 deficiency activated atrial necroptosis through increasing RIPK1 acetylation and subsequent pseudokinase MLKL (mixed lineage kinase domain-like protein) phosphorylation. Consistently, necroptotic inhibitor necrosulfonamide mitigated atrial necroptosis and diminished both the atrial diameter and AF susceptibility of Sirt1mef2c/mef2c mice. Resveratrol prevented age-related AF in rats by activating atrial Sirt1 and inhibiting necroptosis. CONCLUSIONS: Our findings first demonstrated that Sirt1 exerts significant efficacy in countering age-related AF by impeding atrial necroptosis through regulation of RIPK1 acetylation, highlighting that the activation of Sirt1 or the inhibition of necroptosis could potentially serve as a therapeutic strategy for age-related AF.
Asunto(s)
Fibrilación Atrial , Modelos Animales de Enfermedad , Atrios Cardíacos , Ratones Noqueados , Necroptosis , Proteína Serina-Treonina Quinasas de Interacción con Receptores , Sirtuina 1 , Anciano , Animales , Femenino , Humanos , Masculino , Ratones , Ratas , Acetilación , Factores de Edad , Envejecimiento/metabolismo , Envejecimiento/patología , Fibrilación Atrial/metabolismo , Fibrilación Atrial/genética , Fibrilación Atrial/fisiopatología , Fibrilación Atrial/prevención & control , Fibrilación Atrial/patología , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Atrios Cardíacos/fisiopatología , Ratones Endogámicos C57BL , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Ratas Sprague-Dawley , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismo , Proteína Serina-Treonina Quinasas de Interacción con Receptores/genética , Transducción de Señal , Sirtuina 1/metabolismo , Sirtuina 1/genéticaRESUMEN
Chronic smokers have increased risk of fibrosis-related atrial fibrillation. The use of heated-tobacco products (HTPs) is increasing exponentially, and their health impact is still uncertain. We aim to investigate the effects of circulating molecules in exclusive HTP chronic smokers on the fibrotic behavior of human atrial cardiac stromal cells (CSCs). CSCs were isolated from atrial tissue of elective cardiac surgery patients, and exposed to serum lots from young healthy subjects, stratified in exclusive HTP smokers, tobacco combustion cigarette (TCC) smokers, or nonsmokers (NS). CSCs treated with TCC serum displayed impaired migration and increased expression of pro-inflammatory cytokines. Cells cultured with HTP serum showed increased levels of pro-fibrotic markers, and reduced expression of connexin-43. Both TCC and HTP sera increased collagen release and reduced secretion of angiogenic protective factors from CSCs, compared to NS serum. Paracrine support to tube-formation by endothelial cells and to viability of cardiomyocytes was significantly impaired. Treatment with sera of both smokers groups impaired H2O2/NO release balance by CSCs and reduced early phosphorylation of several pathways compared to NS serum, leading to mTOR activation. Cotreatment with rapamycin was able to reduce mTOR phosphorylation and differentiation into aSMA-positive myofibroblasts in CSCs exposed to TCC and HTP sera. In conclusion, the circulating molecules in the serum of chronic exclusive HTP smokers induce fibrotic behavior in CSCs through activation of the mTOR pathway, and reduce their beneficial paracrine effects on endothelial cells and cardiomyocytes. These results point to a potential risk for cardiac fibrosis in chronic HTP users.
Asunto(s)
Fibrosis , Serina-Treonina Quinasas TOR , Productos de Tabaco , Humanos , Serina-Treonina Quinasas TOR/metabolismo , Masculino , Productos de Tabaco/efectos adversos , Femenino , Células del Estroma/metabolismo , Células del Estroma/patología , Células del Estroma/efectos de los fármacos , Fumadores , Persona de Mediana Edad , Adulto , Células Cultivadas , Calor/efectos adversos , Suero/metabolismo , Atrios Cardíacos/patología , Atrios Cardíacos/metabolismo , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Miocitos Cardíacos/efectos de los fármacosRESUMEN
Left atrial strain (LAS) measured by two-dimensional speckle tracking echocardiography (2DSTE) is considered to be a marker of LA structural remodeling, but it remains unsettled. We investigated the potential usefulness and clinical relevance of LAS to detect atrial remodeling including fibrosis by analyzing gene expression in cardiovascular surgery patients. Preoperative 2DSTE was performed in 131 patients (92 patients with sinus rhythm [SR] patients including paroxysmal AF [PAF], 39 atrial fibrillation [AF]) undergoing cardiovascular surgery. Atrial samples were obtained from the left atrial appendages, and mRNA expression level was analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR) in 59 cases (24 PAF, 35 AF). Mean value of left atrial reservoir strain (mLASr) correlated with left atrial volume index (LAVI), and left atrial conduit strain (mLAScd). mLASr also correlated with left atrial contractile strain (mLASct) in SR patients including PAF. mLASr was significantly lower, and LAVI was higher, in the AF group, compared with SR patients including PAF. The expression of COL1A1 mRNA encoding collagen type I α1 significantly increased in AF patients (p = 0.031). mLASr negatively correlated with COL1A1 expression level, and multivariate regression analysis showed that mLASr was an independent predictor of atrial COL1A1 expression level, even after adjusting for age, sex, and BMI. But, neither mLAScd / mLASct nor LAVI (bp) correlated with COL1A1 gene expression. The expression level of COL1A1 mRNA strongly correlated with ECM-related genes (COL3A1, FN1). It also correlated ECM degradation-related genes (MMP2, TIMP1, and TIMP2), pro-fibrogenic cytokines (TGFB1 encoding TGFß1, END1, PDGFD, CTGF), oxidant stress-related genes (NOX2, NOX4), ACE, inflammation-related genes (NLRP, IL1B, MCP-1), and apoptosis (BAX). Among the fibrosis-related genes examined, univariable regression analysis showed that log (COL1A1) was associated with log (TGFB1) (adjusted R2 = 0.685, p<0.001), log (NOX4) (adjusted R2 = 0.622, p<0.001), log (NOX2) (adjusted R2 = 0.611, p<0.001), suggesting that TGFB1 and NOX4 was the potent independent determinants of COL1A1 expression level. mLASr negatively correlated with the ECM-related genes, and fibrosis-related gene expression level including TGFB1, NOX2, and NLRP3 in PAF patients. PAF patients with low mLASr had higher expression of the fibrosis-related gene expression, compared with those with high mLASr. These results suggest that LASr correlates with atrial COL1A1 gene expression associated with fibrosis-related gene expression. Patients with low LASr exhibit increased atrial fibrosis-related gene expression, even those with PAF, highlighting the utility of LAS as a marker for LA fibrosis in cardiovascular surgery patients.
Asunto(s)
Fibrilación Atrial , Remodelación Atrial , Fibrosis , Atrios Cardíacos , Humanos , Masculino , Femenino , Remodelación Atrial/genética , Anciano , Persona de Mediana Edad , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Fibrilación Atrial/genética , Fibrilación Atrial/metabolismo , Fibrilación Atrial/cirugía , Fibrilación Atrial/patología , Fibrilación Atrial/fisiopatología , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Ecocardiografía , Cadena alfa 1 del Colágeno Tipo I , Biomarcadores/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Función del Atrio IzquierdoRESUMEN
The cardiac extracellular matrix (cECM) is fundamental for organ morphogenesis and maturation, during which time it undergoes remodeling, yet little is known about whether mechanical forces generated by the heartbeat regulate this remodeling process. Using zebrafish as a model and focusing on stages when cardiac valves and trabeculae form, we found that altering cardiac contraction impairs cECM remodeling. Longitudinal volumetric quantifications in wild-type animals revealed region-specific dynamics: cECM volume decreases in the atrium but not in the ventricle or atrioventricular canal. Reducing cardiac contraction resulted in opposite effects on the ventricular and atrial ECM, whereas increasing the heart rate affected the ventricular ECM but had no effect on the atrial ECM, together indicating that mechanical forces regulate the cECM in a chamber-specific manner. Among the ECM remodelers highly expressed during cardiac morphogenesis, we found one that was upregulated in non-contractile hearts, namely tissue inhibitor of matrix metalloproteinase 2 (timp2). Loss- and gain-of-function analyses of timp2 revealed its crucial role in cECM remodeling. Altogether, our results indicate that mechanical forces control cECM remodeling in part through timp2 downregulation.
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Matriz Extracelular , Corazón , Inhibidor Tisular de Metaloproteinasa-2 , Pez Cebra , Animales , Pez Cebra/embriología , Pez Cebra/metabolismo , Matriz Extracelular/metabolismo , Inhibidor Tisular de Metaloproteinasa-2/metabolismo , Inhibidor Tisular de Metaloproteinasa-2/genética , Corazón/embriología , Proteínas de Pez Cebra/metabolismo , Proteínas de Pez Cebra/genética , Contracción Miocárdica/fisiología , Miocardio/metabolismo , Morfogénesis , Atrios Cardíacos/embriología , Atrios Cardíacos/metabolismo , Fenómenos Biomecánicos , Regulación del Desarrollo de la Expresión Génica , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/embriologíaRESUMEN
Age is an independent risk factor for atrial fibrillation (AF), and curcumin can delay aging related disease through reducing oxidative stress and inflammation. However, its target in aging-related AF remains unclear. Transfer RNA-derived small RNA (tsRNA) is a novel short non-coding RNA (sncRNA), and exerts a potential regulatory function in aging. This study was to explore the therapeutic targets of curcumin in atrium of aged mice by PANDORA-seq. Aged mice (18 month) were treated with curcumin (100 mg/kg). Rapid transjugular atrial pacing was performed to observe AF inducibility. SA-ß-gal staining, reactive oxygen species (ROS) detection and qRT-PCR were used to assess the degree of aging and oxidative stress/inflammation levels. PANDORA-seq was performed to reveal the differentially expressed sncRNAs in the atrium of mice. The results showed that curcumin reduced the susceptibility AF of aged mice by improving aging-related atrial fibrosis. Compared to young mice (5 month) group, aged mice yielded 473 significantly altered tsRNA sequences, while 947 tsRNA sequences were significantly altered after treated with curcumin. Enrichment analysis revealed that the target genes were mainly related to DNA damage and protein modification. Compared with the 5 month group, the expression levels of mature-mt_tRNA-Val-TAC_CCA_end, mature-mt_tRNA-Glu-TTC_CCA_end, and mature-tRNA-Asp-GTC_CCA_end were up-regulated in the 18 month group, while the expression of mature-mt_tRNA-Thr-TGT_5_end was down-regulated. This trend was reversed in the 18 month + curcumin group. Increased cellular ROS levels, inflammation expression and senescence in aged mice atrium were improved by the down-regulation of mature-mt_tRNA-Val-TAC_CCA_end. In conclusion, our findings identified mature-mt_tRNA-Val-TAC_CCA_end participated in the mechanism of aging-related atrial fibrosis, providing new intervention target of aging-related AF.
Asunto(s)
Envejecimiento , Fibrilación Atrial , Curcumina , Atrios Cardíacos , Estrés Oxidativo , Animales , Curcumina/farmacología , Fibrilación Atrial/genética , Fibrilación Atrial/metabolismo , Fibrilación Atrial/tratamiento farmacológico , Ratones , Envejecimiento/efectos de los fármacos , Envejecimiento/genética , Atrios Cardíacos/efectos de los fármacos , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Estrés Oxidativo/efectos de los fármacos , ARN de Transferencia/genética , ARN de Transferencia/metabolismo , Masculino , ARN Pequeño no Traducido/genética , ARN Pequeño no Traducido/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Fibrosis , Modelos Animales de Enfermedad , Ratones Endogámicos C57BLRESUMEN
Atrial fibrillation (AF) remains challenging to prevent and treat. A key feature of AF is atrial enlargement. However, not all atrial enlargement progresses to AF. Atrial enlargement in response to physiological stimuli such as exercise is typically benign and reversible. Understanding the differences in atrial function and molecular profile underpinning pathological and physiological atrial remodelling will be critical for identifying new strategies for AF. The discovery of molecular mechanisms responsible for pathological and physiological ventricular hypertrophy has uncovered new drug targets for heart failure. Studies in the atria have been limited in comparison. Here, we characterised mouse atria from (1) a pathological model (cardiomyocyte-specific transgenic (Tg) that develops dilated cardiomyopathy [DCM] and AF due to reduced protective signalling [PI3K]; DCM-dnPI3K), and (2) a physiological model (cardiomyocyte-specific Tg with an enlarged heart due to increased insulin-like growth factor 1 receptor; IGF1R). Both models presented with an increase in atrial mass, but displayed distinct functional, cellular, histological and molecular phenotypes. Atrial enlargement in the DCM-dnPI3K Tg, but not IGF1R Tg, was associated with atrial dysfunction, fibrosis and a heart failure gene expression pattern. Atrial proteomics identified protein networks related to cardiac contractility, sarcomere assembly, metabolism, mitochondria, and extracellular matrix which were differentially regulated in the models; many co-identified in atrial proteomics data sets from human AF. In summary, physiological and pathological atrial enlargement are associated with distinct features, and the proteomic dataset provides a resource to study potential new regulators of atrial biology and function, drug targets and biomarkers for AF.