Melatonin increases susceptibility to atrial fibrillation in obesity via Akt signaling impairment in response to lipid overload.

Melatonin has been proven to have antiarrhythmic potential; however, several studies have recently challenged this view. Herein, using a mouse model of obesity-induced atrial fibrillation (AF), we tentatively explored whether exogenous melatonin supplementation could increase AF susceptibility in the context of obesity. We observed that an 8-week drinking administration of melatonin (60 µg/ml in water) induced a greater susceptibility to AF in obese mice, although obesity-induced structural remodeling was alleviated. An investigation of systemic insulin sensitivity showed that melatonin treatment improved insulin sensitivity in obese mice, whereas it inhibited glucose-stimulated insulin secretion. Notably, melatonin treatment inhibited protein kinase B (Akt) signaling in the atria of obese mice and palmitate-treated neonatal rat cardiomyocytes, thereby providing an AF substrate. Melatonin increased lipid stress in obesity, as evidenced by elevated lipid accumulation and lipolysis-related gene expression, thus contributing to the impairment in atrial Akt signaling. Taken together, our results demonstrated that melatonin could increase AF susceptibility in obesity, probably due to increased lipid stress and resultant impairment of atrial Akt signaling. Our findings suggest that special precautions should be taken when administering melatonin to obese subjects.

Successful non-operative management of atrioesophageal fistula after combined therapy of catheter ablation and left atrial appendage closure for atrial fibrillation: A case report.

Atrioesophageal fistula (AEF) is a rare but devastating complication of radiofrequency ablation (RFCA) for atrial fibrillation (AF) and is associated with high mortality rates. Whereas most cases of AEF are treated by emergency surgical interventions, we report a case of paroxysmal AF with AEF after combined therapy of catheter ablation and percutaneous left atrial appendage closure (LAAC), which was treated successfuly without major surgery or esophageal stenting. He was presented 18 days after the procedure, suffering chest pain, fever, and a transient loss of consciousness. Computed tomography (CT) of the chest disclosed a small accumulation of air in the region of the left atrium adjacent to the esophagus, suggesting AEF. Supported by early aggressive antibiotic therapy, pericardial drainage and a fasting state with adequate parenteral nutrition, resulted in improvement of his condition with no recurrence of symptoms. Subsequent chest CT scans confirmed disappearance of the leaked air and the patient was discharged home 28 days after admission with no neurological compromise. Early detection, rapid treatment and constant awareness of potential fatal consequences are prerequisites for successful treatment of this complication and prevention of fatal outcome.

Construction and validation of a cuproptosis-related diagnostic gene signature for atrial fibrillation based on ensemble learning.

BACKGROUND: Atrial fibrillation (AF) is the most common type of cardiac arrhythmia. Nonetheless, the accurate diagnosis of this condition continues to pose a challenge when relying on conventional diagnostic techniques. Cell death is a key factor in the pathogenesis of AF. Existing investigations suggest that cuproptosis may also contribute to AF. This investigation aimed to identify a novel diagnostic gene signature associated with cuproptosis for AF using ensemble learning methods and discover the connection between AF and cuproptosis. RESULTS: Two genes connected to cuproptosis, including solute carrier family 31 member 1 (SLC31A1) and lipoic acid synthetase (LIAS), were selected by integration of random forests and eXtreme Gradient Boosting algorithms. Subsequently, a diagnostic model was constructed that includes the two genes for AF using the Light Gradient Boosting Machine (LightGBM) algorithm with good performance (the area under the curve value > 0.75). The microRNA-transcription factor-messenger RNA network revealed that homeobox A9 (HOXA9) and Tet methylcytosine dioxygenase 1 (TET1) could target SLC31A1 and LIAS in AF. Functional enrichment analysis indicated that cuproptosis might be connected to immunocyte activities. Immunocyte infiltration analysis using the CIBERSORT algorithm suggested a greater level of neutrophils in the AF group. According to the outcomes of Spearman's rank correlation analysis, there was a negative relation between SLC31A1 and resting dendritic cells and eosinophils. The study found a positive relationship between LIAS and eosinophils along with resting memory CD4+ T cells. Conversely, a negative correlation was detected between LIAS and CD8+ T cells and regulatory T cells. CONCLUSIONS: This study successfully constructed a cuproptosis-related diagnostic model for AF based on the LightGBM algorithm and validated its diagnostic efficacy. Cuproptosis may be regulated by HOXA9 and TET1 in AF. Cuproptosis might interact with infiltrating immunocytes in AF.

[Metabolic mechanism and intervention strategy of atrial fibrillation in the elderly].

Atrial fibrillation (AF) is a cardiovascular epidemic that occurs primarily in the elderly with primary cardiovascular diseases, leading to severe consequences such as stroke and heart failure. The heart is an energy-consuming organ, which requires a high degree of metabolic flexibility to ensure a quick switch of metabolic substrates to meet its energy needs in response to physiological and pathological stimulation. Metabolism is closely related to the occurrence of AF, and AF patients manifest metabolic inflexibility, such as insulin resistance and the metabolic shift from aerobic metabolism to anaerobic glycolysis. Moreover, our research group and the others have shown that metabolic inflexibility is a crucial pathologic mechanism for AF. Energy metabolism is closely linked to the aging process and aging-related diseases, and impaired metabolic flexibility is considered as an essential driver of aging. Therefore, this review focuses on the alteration of metabolic flexibility in the elderly and reveals that impaired metabolic flexibility may be an important driver for the high prevalence of AF in the elderly, hoping to provide intervention strategies for the prevention and treatment of AF in the elderly.

Upregulation of FAM129B protects cardiomyocytes from hypoxia/reoxygenation-induced injury by inhibiting apoptosis, oxidative stress, and inflammatory response via enhancing Nrf2/ARE activation.

Family with sequence similarity 129, member B (FAM129B) has been identified as a novel cytoprotective protein that facilitates the survival of detrimentally stimulated cells. However, whether FAM129B is involved in regulating cardiomyocyte survival after myocardial ischemia-reperfusion injury is unknown. The goal of this work was to evaluate the potential role of FAM129B in regulating hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury in vitro. We demonstrated that exposure to H/R markedly downregulated the expression of FAM129B in cardiomyocytes. Functional experiments revealed that the upregulation of FAM129B improved H/R-exposed cardiomyocyte viability, and ameliorated H/R-induced cardiomyocyte apoptosis, the generation of reactive oxygen species (ROS), and pro-inflammatory cytokine release. The upregulation of FAM129B significantly increased the nuclear expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), and reinforced Nrf2/antioxidant response element (ARE) activation in H/R-exposed cardiomyocytes. Moreover, FAM129B modulates Nrf2/ARE signaling in a Kelchlike ECH-associated protein 1-dependent manner. Notably, the inhibition of Nrf2 significantly blocked FAM129B-overexpression-induced cardioprotective effects in H/R-exposed cardiomyocytes. In summary, the findings of our work demonstrate that the upregulation of FAM129B ameliorates H/R-induced cardiomyocyte injury via enhancing Nrf2/ARE activation. Thus, our study indicates that FAM129B may play a role in myocardial ischemia-reperfusion injury and has the potential to be used as a cardioprotective target.

Metabolic Inflexibility as a Pathogenic Basis for Atrial Fibrillation.

Atrial fibrillation (AF), the most common sustained arrhythmia, is closely intertwined with metabolic abnormalities. Recently, a metabolic paradox in AF pathogenesis has been suggested: under different forms of pathogenesis, the metabolic balance shifts either towards (e.g., obesity and diabetes) or away from (e.g., aging, heart failure, and hypertension) fatty acid oxidation, yet they all increase the risk of AF. This has raised the urgent need for a general consensus regarding the metabolic changes that predispose patients to AF. "Metabolic flexibility" aptly describes switches between substrates (fatty acids, glucose, amino acids, and ketones) in response to various energy stresses depending on availability and requirements. AF, characterized by irregular high-frequency excitation and the contraction of the atria, is an energy challenge and triggers a metabolic switch from preferential fatty acid utilization to glucose metabolism to increase the efficiency of ATP produced in relation to oxygen consumed. Therefore, the heart needs metabolic flexibility. In this review, we will briefly discuss (1) the current understanding of cardiac metabolic flexibility with an emphasis on the specificity of atrial metabolic characteristics; (2) metabolic heterogeneity among AF pathogenesis and metabolic inflexibility as a common pathological basis for AF; and (3) the substrate-metabolism mechanism underlying metabolic inflexibility in AF pathogenesis.

Necroptosis is required for atrial fibrillation and involved in aerobic exercise-conferred cardioprotection.

Necroptosis, a novel programmed cell death, plays a critical role in the development of fibrosis, yet its role in atrial fibrillation (AF) remains elusive. Mounting evidence demonstrates that aerobic exercise improves AF-related symptoms and quality of life. Therefore, we explored the role of necroptosis in AF pathogenesis and exercise-conferred cardioprotection. A mouse AF model was established either by calcium chloride and acetylcholine (CaCl2 -Ach) administration for 3 weeks or high-fat diet (HFD) feeding for 12 weeks, whereas swim training was conducted 60 min/day, for 3-week duration. AF susceptibility, heart morphology and function and atrial fibrosis were assessed by electrophysiological examinations, echocardiography and Masson's trichrome staining, respectively. Both CaCl2 -Ach administration and HFD feeding significantly enhanced AF susceptibility (including frequency and duration of episodes), left atrial enlargement and fibrosis. Moreover, protein levels of necroptotic signaling (receptor-interacting protein kinase 1, receptor-interacting protein kinase 3, mixed lineage kinase domain-like protein and calcium/calmodulin-dependent protein kinase II or their phosphorylated forms) were markedly elevated in the atria of AF mice. However, inhibiting necroptosis with necrostatin-1 partly attenuated CaCl2 -Ach (or HFD)-induced fibrosis and AF susceptibility, implicating necroptosis as contributing to AF pathogenesis. Finally, we found 3-week swim training inhibited necroptotic signaling, consequently decreasing CaCl2 -Ach-induced AF susceptibility and atrial structural remodeling. Our findings identify necroptosis as a novel mechanism in AF pathogenesis and highlight that aerobic exercise may confer benefits on AF via inhibiting cardiac necroptosis.

Hyper-O-GlcNAcylation impairs insulin response against reperfusion-induced myocardial injury and arrhythmias in obesity.

Myocardial ischemia/reperfusion (I/R) injury is a major determinant of morbidity and mortality in patients undergoing treatment for cardiac disease. A variety of treatments are reported to have benefits against reperfusion injury, yet their cardioprotective effects seem to be diminished in obesity, and the underlying mechanism remains elusive. In this study, we found that db/db mice exhibit cardiac hyper-O-GlcNAcylation. In parallel, palmitate treatment (200 mM; 12 h) in H9c2 cells showed an increase in global protein O-GlcNAcylation, along with an impaired insulin response against reperfusion injury. To investigate whether O-GlcNAcylation underlies this phenomenon, glucosamine was used to increase global protein O-GlcNAc levels. Interestingly, histological staining, electrophysiological studies, serum cardiac markers and oxidative stress biomarker assays showed that preischemic treatment with glucosamine attenuated insulin cardioprotection against myocardial infarction, arrhythmia and oxidative stress. Mechanistically, glucosamine treatment decreased insulin-stimulated Akt phosphorylation, a key modulator of cell survival. Furthermore, inhibition of O-GlcNAcylation via 6-diazo-5-oxo-l-norleucine (DON) apparently increased insulin-induced Akt phosphorylation and restored its cardioprotective response against reperfusion injury in palmitate-induced insulin-resistant H9c2 cells. Our findings demonstrated that obesity-induced hyper-O-GlcNAcylation might contribute to the attenuation of insulin cardioprotection against I/R injury.

Association between apolipoprotein B/A1 ratio and coronary plaque vulnerability in patients with atherosclerotic cardiovascular disease: an intravascular optical coherence tomography study.

BACKGROUND: Apolipoprotein (Apo) A1 and Apo B are strongly associated with the risk of atherosclerotic cardiovascular disease (ASCVD). However, the relationship between the Apo B/A1 ratio and the morphology of coronary vulnerable plaques has not been fully elucidated in patients with ASCVD. METHODS: A total of 320 patients with ASCVD undergoing percutaneous coronary intervention were enrolled and assigned into acute coronary syndrome (ACS) or chronic coronary syndrome (CCS) group. The morphology of culprit plaque was analyzed by intravascular optical coherence tomography. Association between the Apo B/A1 ratio and coronary vulnerable plaques were evaluated using logistic regression models and receiver operator characteristic (ROC) curve analyses. RESULTS: The Apo B/A1 ratio was higher in ACS patients than CCS patients (0.77 ± 0.28 vs. 0.64 ± 0.22, P < 0.001) and it was also higher in patients with plaque rupture, erosion or thrombus than those without culprit plaques. The high Apo B/A1 ratio was associated with high percent of vulnerable plaques compared with low ratio group. The Apo B/A1 ratio was negatively related to fibrous cap thickness in lipid-rich plaque (r = - 0.228, P = 0.043). Univariate and multivariate logistic regression analyses revealed that the Apo B/A1 ratio was an independent factor of plaque rupture, erosion, and thrombus. The area under the ROC curve of the Apo B/A1 ratio for plaque rupture, erosion, and thrombus were 0.632, 0.624, and 0.670 respectively (P < 0.001 for all), which were higher than that of low-density lipoprotein cholesterol. CONCLUSIONS: The Apo B/A1 ratio is an independent predictor for plaque rupture, erosion, and thrombus in patients with ASCVD.

Anti-arrhythmic and anti-heart failure effects of low-level electrical stimulation on aortic root ventricular ganglionated plexi.

BACKGROUND: It remains uncertain whether low-level electrical stimulation (LL-ES) of the ventricular ganglionated plexi (GP) improves heart function. This study investigated the anti-arrhythmic and anti-heart failure effects of LL-ES of the aortic root ventricular GP (ARVGP). METHODS: Thirty dogs were divided randomly into control, drug, and LL-ES groups after performing rapid right ventricular pacing to establish a heart failure (HF) model. The inducing rate of arrhythmia; levels of bioactive factors influencing HF, including angiotensin II type I receptor (AT-1R), transforming growth factor-beta (TGF-ß), matrix metalloproteinase (MMP), and phosphorylated extracellular signal-regulated kinase (p-ERK1/2); left ventricular stroke volume (LVSV), and left ventricular ejection fraction (LVEF)were measured after treatment with placebo, drugs, and LL-ES. RESULTS: The inducing rate of atrial arrhythmia decreased from 60% in the control group to 50% in the drug group and 10% in the LL-ES group (p = .033 vs. drug group) after 1 week of treatment. The ventricular effective refractory period was prolonged from 139 ± 8 ms in the drug group to 166 ± 13 ms in the LL-ES group (p = .001). Compared to the drug group, the expressions of AT-1R, TGF-ß, and MMP proteins were down-regulated in the LL-ES group, whereas that of p-ERK1/2 was significantly increased (all p = .001). Moreover, in the LL-ES group, LVSV increased markedly from 13.16 ± 0.22 to 16.86 ± 0.27 mL, relative to that in the drug group (p = .001), and LVEF increased significantly from 38.48% ± 0.53% to 48.94% ± 0.57% during the same time frame (p = .001). CONCLUSION: Short-term LL-ES of ARVGP had both anti-arrhythmic and anti-inflammatory effects and contributed to the treatment of tachycardia-induced HF and its associated arrhythmia.

[Active components and action mechanism of Shenmai Injection in treatment of atrial fibrillation based on network pharmacology and molecular docking].

This study aims to explore the active components and molecular mechanism of Shenmai Injection in the treatment of atrial fibrillation(AF) based on the application of network pharmacology and molecular docking technology. The chemical components of single herbs of Shenmai Injection were collected from TCMSP and TCMID, with the standard chemical name and PubChem CID(referred to as CID) obtained from PubChem database. The active components were screened using SwissADME, and their targets were predicted using SwissTargetPrediction. Targets related to AF treatment were identified using GeneCards, OMIM, and other databases. Venn diagram was constructed using Venny 2.1 to obtain the intersection targets. The single herb-active component-potential target network was constructed using Cytoscape, and the clusterProfiler R function package was used to perform the gene ontology(GO) and Kyoto encyclopedia of genes and genomes(KEGG) pathway enrichment. The protein-protein interaction(PPI) network of intersection targets was generated based on the STRING database. The hub target protein was identified by visualization using Cytoscape, and then docked to its reverse-selected active components. The analysis showed that there were 65 active components with 681 corresponding targets in Shenmai Injection, 2 798 targets related to AF treatment, and 235 intersection targets involving 2 549 GO functions and 153 KEGG pathways. Finally, hub target proteins, including RAC-alpha serine/threonine-protein kinase(AKT1), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha(PIK3 CA), and estrogen receptor 1(ESR1), were screened out by PPI network visualization. The molecular docking was performed for 39 active components screened out in reverse, among which 30 active components de-monstrated high affinity. Among them, homoisoflavanoids CID 10871974, CID 5319742, and CID 10361149 had stronger affinity docking with AKT1. This study preliminarily indicates that Shenmai Injection treats AF through multiple components, multiple targets, and multiple pathways. Homoisoflavonoids of Ophiopogon japonicus are its important active components, which target AKT1 to regulate metabolism, inflammation, and apoptosis in AF treatment.

Electrophysiological Measurement of Rat Atrial Epicardium Using a Novel Stereotaxic Apparatus.

Flexible, in vivo maneuverable electrophysiology mapping techniques are not available in rat models. A novel cardiac stereotactic electrophysiology epicardial mapping system (CREAMS) allows for various measurements, including: (1) recording unipolar electrograms at multiple sites; (2) positioning of mapped sites and precision testing (Distance between the two "centers" = 297 ± 54 µm, n = 15); (3) evaluation of electrophysiology in an in vivo Sprague-Dawley rat model with high-frequency stimulation (HFS)-induced Atrial fibrillation (AF) at high right atrium (HRA) sites. We found that of the right atrium dispersion of effective refractory period (P < 0.05) and the window of vulnerability (P < 0.01) were significantly increased (P < 0.05) after HRA HFS. CREAMS has the potential for convenient electrophysiology assessment in a rat AF model through stereo-positioning, and flexible operating manipulation.

Simvastatin Protects Heart from Pressure Overload Injury by Inhibiting Excessive Autophagy.

Cardiac hypertrophy is an independent predictor of cardiovascular morbidity and mortality. To identify the mechanisms by which simvastatin inhibits cardiac hypertrophy induced by pressure overload, we determined effects of simvastatin on 14-3-3 protein expression and autophagic activity. Simvastatin was administered intragastrically to Sprague-Dawley (SD) rats before abdominal aortic banding (AAB). Neonatal rat cardiomyocytes (NRCs) were treated with simvastatin before angiotensin II (AngII) stimulation. 14-3-3, LC3, and p62 protein levels were determined by western blot. Autophagy was also measured by the double-labeled red fluorescent protein-green fluorescent protein autophagy reporter system. Simvastatin alleviated excessive autophagy, characterized by a high LC3II/LC3I ratio and low level of p62, and blunted cardiac hypertrophy while increasing 14-3-3 protein expression in rats that had undergone AAB. In addition, it increased 14-3-3 expression and inhibited excessive autophagy in NRCs exposed to AngII. Our study demonstrated that simvastatin may inhibit excessive autophagy, increase 14-3-3 expression, and finally exert beneficial effects on cardioprotection against pressure overload.

Relationship among adiponectin, insulin resistance and atherosclerosis in non-diabetic hypertensive patients and healthy adults.

Adiponectin, which is secreted specifically by adipose tissue, has been shown to have anti-atherogenic and anti-inflammatory effects and to improve insulin resistance (IR). The aim of this study was to determine the correlations among adiponectin, IR and atherosclerosis in non-diabetic hypertensive patients and healthy volunteers. In this case control study, we collected complete demographic data from and measured several laboratory parameters in all enrolled subjects. The homeostasis model of assessment for insulin resistance (HOMA-IR) was calculated as an insulin sensitivity index. The atherogenic index of plasma (AIP), which is calculated as log (triglyceride (TG)/high-density lipoprotein cholesterol (HDL-C)), was a significant predictor of atherosclerosis and was a better predictor of atherosclerosis than low-density lipoprotein cholesterol (LDL-C). Plasma adiponectin, interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1) and matrix metalloprotein-9 (MMP-9) concentrations were determined using enzyme-linked immunosorbent assay (ELISA). All data were analyzed using Statistical Product and Service Solutions for Windows (SPSS) 13.0 software. A total of 309 participants were enrolled in the study. Hypertensive patients with IR (n = 93) displayed significantly higher HOMA-IR values and AIPs and lower adiponectin levels than hypertensive patients without IR (n = 121) and healthy adults (n = 95) (P < 0.05). Furthermore, circulating IL-6, MCP-1 and MMP-9 concentrations differed significantly between hypertensive patients and healthy adults (P < 0.05). Additionally, adiponectin levels were found to be inversely correlated with IL-6, MCP-1, and MMP-9 levels; HOMA-IR values; and AIPs in the clinical study. HOMA-IR values and adiponectin and creatinine (Cr) concentrations remained independently associated with AIPs in all participants after adjustment for confounders via multivariate linear regression. Low adiponectin levels are positively correlated with decreased insulin sensitivity, increased pro-inflammatory cytokine production and worsening atherosclerosis in hypertensive patients and healthy adults.

ZLN005 protects cardiomyocytes against high glucose-induced cytotoxicity by promoting SIRT1 expression and autophagy.

Diabetic cardiomyopathy increases the risk for the development of heart failure independent of coronary artery disease and hypertension. Either type 1 or type 2 diabetes is often accompanied by varying degrees of hyperglycemia, which has been proven to induce myocardial apoptosis in animal models. Recently, a novel small molecule, ZLN005, has been reported to show antidiabetic efficacy in a mouse model, possibly by induction of PGC-1α expression. In this study, we investigated whether ZLN005 protects cardiomyocytes against high glucose-induced cytotoxicity and the mechanisms involved. Neonatal mouse cardiomyocytes were incubated with media containing 5.5 or 33mM glucose for 24h in the presence or absence of ZLN005. ZLN005 treatment led to ameliorated cardiomyocyte oxidative injury, enhanced cell viability, and reduced apoptosis in the high glucose environment. Western blot analysis revealed that high glucose suppressed cardiomyocyte autophagy, whereas ZLN005 increased the expression of autophagy marker proteins ATG5, beclin1, and LC3 II/LC3 I; this increase was accompanied by increased expression of SIRT1. Furthermore, EX527, a SIRT1-specific inhibitor, weakened the protective effects of ZLN005 on cardiomyocytes subjected to high glucose. Taken together, these results suggest that ZLN005 suppresses high glucose-induced cardiomyocyte injury by promoting SIRT1 expression and autophagy.

Co-culture with neonatal cardiomyocytes enhances the proliferation of iPSC-derived cardiomyocytes via FAK/JNK signaling.

BACKGROUND: We previously reported that the pluripotent stem cells can differentiate into cardiomyocytes (CMs) by co-culture with neonatal CMs (NCMs) in vitro. However, the involving mechanism is not clear. METHODS: Mouse induced pluripotent stem cells (iPSCs) were cultured in hanging drops to form embryoid bodies (EBs) and to induce myocardial differentiation. Co-culture of EBs and NCMs was established in a transwell insert system, while EBs grown alone in the wells were used as controls. RESULTS: Co-culture with NCMs markedly increased the generation of functional CMs from iPSCs. The focal adhesion kinase (FAK) phosphorylation, and c-Jun N-terminal kinase (JNK) phosphorylation in co-culture were higher than that in EBs grown alone. Treating FAK small interfering RNA (FAK siRNA) or specific inhibitor for JNK (SP600125) to iPSCs significantly reduced the phosphorylation of JNK and the expressions of Mef2c and Bcl-2. The expressions of cTnT and MLC-2V were also decreased. Our results revealed that co-culture with NCMs significantly enhance the differentiation ability of iPSCs by increasing Mef2c and Bcl-2 expressions concomitantly with a marked augment on cell proliferation through JNK signaling pathways. CONCLUSIONS: These findings indicated that co-culture of EBs with NCMs induces genes expressed in a mature pattern and stimulates the proliferation of iPSC-derived CMs (iPS-CMs) by activating FAK/JNK signaling.

PD-1/PD-L1 expression on CD(4+) T cells and myeloid DCs correlates with the immune pathogenesis of atrial fibrillation.

Although immuno-inflammatory response contributes to pathogenesis of AF, molecular and cellular mechanism in this process remains poorly understood. Recently, increasing evidence suggests that Programmed death-1 (PD-1)/PD-1 ligand (PD-L) pathway may be a potential pathway participating in AF pathogenesis. In this study, we detected the PD-1 and PD-L1, 2 expression on peripheral blood function cells by flow cytometry in 91 atrial fibrillation (AF) patients and 35 healthy volunteers. The expression of PD-1 on CD(4+) T cells and PD-L1 on myeloid dendritic cells (mDCs) in AF patients is significantly down-regulated compared with healthy volunteers. In addition, the extent of PD-1/PD-L1 down-regulation is closely related with AF burden. More importantly, Allogeneic mixed leukocyte reactions (MLR) shows that the mDCs PD-L1 down-regulation is associated with increased T cell (CD(4+) and CD(8+)) proliferation, increased type 1 effector cytokines (IL-2 and IFN-γ) secretion, and decreased type 2 effector cytokine (IL-10) secretion. Then, PD-L1 up-regulation by the stimulation of IFN-α can significantly convert this representation. Collectively, our report suggest that T(CD(4+))/mDCs-associated PD-1/PD-L1 pathway plays a key role in AF immune regulation. PD-1/PD-L1 down-regulation in AF patients promotes T cells function and may contribute to AF pathogenesis.

Three-dimensional poly-(ε-caprolactone) nanofibrous scaffolds directly promote the cardiomyocyte differentiation of murine-induced pluripotent stem cells through Wnt/ß-catenin signaling.

BACKGROUND: Environmental factors are important for stem cell lineage specification, and increasing evidence indicates that the nanoscale geometry/topography of the extracellular matrix (ECM) directs stem cell fate. Recently, many three-dimensional (3D) biomimetic nanofibrous scaffolds resembling many characteristics of the native ECM have been used in stem cell-based myocardial tissue engineering. However, the biophysical role and underlying mechanism of 3D nanofibrous scaffolds in cardiomyocyte differentiation of induced pluripotent stem cells (iPSCs) remain unclear. RESULTS: Here, we fabricated a 3D poly-(ε-caprolactone) (PCL) nanofibrous scaffold using the electrospinning method and verified its nanotopography and porous structure by scanning electron microscopy. We seeded murine iPSCs (miPSCs) directly on the 3D PCL nanofibrous scaffold and initiated non-directed, spontaneous differentiation using the monolayer method. After the 3D PCL nanofibrous scaffold was gelatin coated, it was suitable for monolayer miPSC cultivation and cardiomyocyte differentiation. At day 15 of differentiation, miPSCs differentiated into functional cardiomyocytes on the 3D PCL nanofibrous scaffold as evidenced by positive immunostaining of cardiac-specific proteins including cardiac troponin T (cTnT) and myosin light chain 2a (MLC2a). In addition, flow cytometric analysis of cTnT-positive cells and cardiac-specific gene and protein expression of cTnT and sarcomeric alpha actinin (α-actinin) demonstrated that the cardiomyocyte differentiation of miPSCs was more efficient on the 3D PCL nanofibrous scaffold than on normal tissue culture plates (TCPs). Furthermore, early inhibition of Wnt/ß-catenin signaling by the selective antagonist Dickkopf-1 significantly reduced the activity of Wnt/ß-catenin signaling and decreased the cardiomyocyte differentiation of miPSCs cultured on the 3D PCL nanofibrous scaffold, while the early activation of Wnt/ß-catenin signaling by CHIR99021 further increased the cardiomyocyte differentiation of miPSCs. CONCLUSION: These results indicated that the electrospun 3D PCL nanofibrous scaffolds directly promoted the cardiomyocyte differentiation of miPSCs, which was mediated by the activation of the Wnt/ß-catenin signaling during the early period of differentiation. These findings highlighted the biophysical role of 3D nanofibrous scaffolds during the cardiomyocyte differentiation of miPSCs and revealed its underlying mechanism involving Wnt/ß-catenin signaling, which will be helpful in guiding future stem cell- and scaffold-based myocardium bioengineering.

Efficacy of different doses of atorvastatin treatment on serum levels of 8-hydroxy-guanin (8-OHdG) and cardiac function in patients with ischemic cardiomyopathy.

OBJECTIVE: To compare the efficacy of 40 mg and l0 mg atorvastatin on serum levels of 8-Hydroxy-Guanin (8-OHdG) and the cardiac function in patients with ischemic cardiomyopathy (ICM). METHODS: One hundred twenty three hospitalized ICM patients and 120 healthy controls were included in this study. All subjects were randomly divided into two groups: 10 mg/d atorvastatin group (n=62) and 40 mg/d atorvastatin group (n=61). Serum levels of C-reactive protein (CRP), creatine kinase, glutamic-pyruvic transaminase, lipids and B-type natriuretic peptide (BNP) were tested in all subjects both at the initial phase and the terminal phase of this study. Adverse drug reaction events were recorded in this study. Echocardiographic method was applied to compare the cardiac function before and after treatment in the double blind study. Serum 8-OHdG levels were tested by enzyme-linked immunosorbent assay (ELISA) before and after treatment, and the results in atorvastatin treatment groups were compared with the healthy controls. RESULTS: Serum 8-OHdG levels in ICM patients were significantly higher than that in normal control groups (p<0.05). There was significant difference of Serum 8-OHdG levels in 40 mg/d atorvastatin group (p<0.05), but was no significant difference in 10 mg/d atorvastatin group before and after the treatment. The 8-OHdG level in 40 mg/d atorvastatin group was significantly lower than that in 10 mg/d atorvastatin group before the treatment as well as after the treatment (p<0.05). The systolic and diastolic function improved significantly in 40 mg/d atorvastatin group before and after treatment, as well as in comparison with 10 mg/d atorvastatin group (p<0.05). CONCLUSION: Serum 8-OHdG possibly plays an important role in the pathogenesis of ICM. Atorvastatin is safe and effective in ICM treatment; furthermore atorvastatin which also has independent lipid lowering effect, is significantly better in the dose of 40 mg/day.

QKI deficiency promotes FoxO1 mediated nitrosative stress and endoplasmic reticulum stress contributing to increased vulnerability to ischemic injury in diabetic heart.

Hearts of diabetic individuals are susceptible to ischemia/reperfusion (I/R) injury. The RNA-binding protein Quaking (QKI) is known to link intracellular signaling to cellular survival and QKI dysregulation may contribute to human diseases. However, the function of QKI in diabetic hearts remains unknown. The current study attempted to identify new molecular mechanisms that potentially contribute to the susceptibility to ischemic injury in diabetic myocardium. Diabetic ob/ob mice or wild-type C57BL/6J mice were subjected to in vivo myocardial I/R. Myocardial infarct size and apoptosis, QKI5 and FoxO1 expression, nitrosative stress (NS) and ER stress were compared. Knockdown of FoxO1 was obtained by intramyocardial injection of FoxO1 specific small interfering RNA (siRNA, 20µg), and upregulation of QKI5 was acquired by injecting adenovirus encoding-QKI5. Obvious NS stress was observed in the myocardium of ob/ob mice represented by elevated iNOS expression, total NO content and nitrotyrosine content. Administration of 1400W or M40401 partly reduced the caspase-3 activity in ob/ob myocardium encountering I/R (P<0.05). Higher ER stress was also observed represented by increased p-PERK, p-eIF2α and expression of CHOP in ob/ob myocardium. ER stress inhibitor did not affect the excessive NS stress, but partially reduced I/R-induced caspase-3 activity in ob/ob hearts (P<0.05). FoxO1 was overactivated in ob/ob myocardium, and knockdown of FoxO1 attenuated both levels of NS stress and ER stress (P<0.05). Furthermore, QKI5 expression was deficient in ob/ob myocardium. Upregulation of QKI5 diminished FoxO1 expression together with NS and ER stress in ob/ob myocardium, further reducing MI/R injury. Finally, QKI5 overexpression destabilized FoxO1 mRNA in cardiomyocytes. These results suggested that QKI5 deficiency contributed to the overactivation of FoxO1 in ob/ob animals and subsequently magnified nitrosative stress and ER stress, which enhances the ischemic intolerance of diabetic hearts.