Cardiomyocyte and endothelial cells play distinct roles in the tumour necrosis factor (TNF)-dependent atrial responses and increased atrial fibrillation vulnerability induced by endurance exercise training in mice.

AIMS: Endurance exercise is associated with an increased risk of atrial fibrillation (AF). We previously established that adverse atrial remodelling and AF susceptibility induced by intense exercise in mice require the mechanosensitive and pro-inflammatory cytokine tumour necrosis factor (TNF). The cellular and mechanistic basis for these TNF-mediated effects is unknown. METHODS AND RESULTS: We studied the impact of Tnf excision, in either atrial cardiomyocytes or endothelial cells (using Cre-recombinase expression controlled by Nppa or Tie2 promoters, respectively), on the cardiac responses to six weeks of intense swim exercise training. TNF ablation, in either cell type, had no impact on the changes in heart rate, autonomic tone, or left ventricular structure and function induced by exercise training. Tnf excision in atrial cardiomyocytes did, however, prevent atrial hypertrophy, fibrosis, and macrophage infiltration as well as conduction slowing and increased AF susceptibility arising from exercise training. In contrast, endothelial-specific excision only reduced the training-induced atrial hypertrophy. Consistent with these cell-specific effects of Tnf excision, inducing TNF loss from atrial cardiomyocytes prevented activation of p38MAPKinase, a strain-dependent downstream mediator of TNF signalling, without affecting the atrial stretch as assessed by atrial pressures induced by exercise. Despite TNF's established role in innate immune responses and inflammation, neither acute nor chronic exercise training caused measurable NLRP3 inflammasome activation. CONCLUSIONS: Our findings demonstrate that adverse atrial remodelling and AF vulnerability induced by intense exercise require TNF in atrial cardiomyocytes whereas the impact of endothelial-derived TNF is limited to hypertrophy modulation. The implications of the cell autonomous effects of TNF and crosstalk between cells in the atria are discussed.

Silencing of UTX Mitigates Aging-Associated Cardiac Fibrosis via Blocking Cardiac Fibroblasts-to-Myofibroblasts Trans-Differentiation.

BACKGROUND: Cardiac fibrosis increases with age. Fibroblast activation plays an essential role in cardiac fibrosis. Histone modifications are involved in various chromatin-dependent processes. Attenuation of the histone H3 trimethylation on lysine 27 demethylase UTX by RNA interference or heterozygous mutation extends lifespan in worm. The objective of this study was to explore whether epigenetic silencing of UTX mitigates aging-associated cardiac fibrosis. METHODS: Middle-aged mice (15 months old) were used and started to receive adeno-associated virus-scrambled-small hairpin RNA and adeno-associated virus-UTX-small hairpin RNA every 3 months from 15 months to 21 months, respectively. The mice were euthanized at 24 months of age (length of the study). RESULTS: Adeno-associated virus-UTX-small hairpin RNA delivery significantly attenu-ated aging-associated increase in blood pressure, especially in diastolic blood pressure, indicating silencing of UTX rescued aging-associated cardiac dysfunction. Aging-associated cardiac fibrosis is characterized by fibroblast activation and abundant extracellular matrix deposition, including collagen deposition and alpha smooth muscle actin activation. Silencing of UTX abolished collagen deposition and alpha smooth muscle actin activation, decreased serum transforming growth factor ß, blocked cardiac fibro blast s-to- myofi brobl asts trans-differentiation by elevation of cardiac resident mature fibroblast markers, TCF21, and platelet-derived growth factor receptor alpha, which are important proteins for maintaining cardiac fibroblast physiological function. In the mechanistic study, adeno-associated virus-UTX-small hairpin RNA blocked transforming growth factor ß-induced cardiac fibro blast s-to- myofi brobl asts trans-differentiation in isolated fibroblasts from 24-month-old mouse heart. The same results demonstrated as the in vivo study. CONCLUSIONS: Silencing of UTX attenuates aging-associated cardiac fibrosis via blocking cardiac fibroblasts-to-myofibroblasts transdifferentiation and consequently attenuates aging-associated cardiac dysfunction and cardiac fibrosis.

Congenital coronary artery-left ventricular multiple micro-fistulas and hypertrophic cardiomyopathy: a case report and literature review.

BACKGROUND: Coronary artery-left ventricular multiple micro-fistulas (CA-LVMMFs) is a rare congenital vascular anomaly that may present with no obvious clinical symptoms or a typical angina attack. CA-LVMMFs is usually found unexpectedly during coronary angiography (CAG). CASE PRESENTATION: We report a case of a 65-year-old man admitted to the hospital with acute coronary syndrome. CA-LVMMFs was found during coronary angiography. Echocardiography showed apical hypertrophy and blood flow signals were seen in the apical myocardium, connected with the left ventricle. We searched the MEDLINE database and found 39 relevant reports. We made statistics on the clinical characteristics of these patients and found half involved hypertrophy or perfusion defects in the ventricular septum or apex. CONCLUSION: As a rare congenital anomaly, the effect of CA-LVMMFs on patients is unclear. By reporting a case and summarizing literature reports, we found that CA-LVMMFs may be associated with myocardial hypertrophy, especially ventricular septal and apical hypertrophy.

Differential negative effects of acute exhaustive swim exercise on the right ventricle are associated with disproportionate hemodynamic loading.

Acute exhaustive endurance exercise can differentially impact the right ventricle (RV) versus the left ventricle (LV). However, the hemodynamic basis for these differences and its impact on postexercise recovery remain unclear. Therefore, we assessed cardiac structure and function along with hemodynamic properties of mice subjected to single bouts (216 ± 8 min) of exhaustive swimming (ES). One-hour after ES, LVs displayed mild diastolic impairment compared with that in sedentary (SED) mice. Following dobutamine administration to assess functional reserve, diastolic and systolic function were slightly impaired. Twenty-four hours after ES, LV function was largely indistinguishable from that in SED. By contrast, 1-h post swim, RVs showed pronounced impairment of diastolic and systolic function with and without dobutamine, which persisted 24 h later. The degree of RV impairment correlated with the time-to-exhaustion. To identify hemodynamic factors mediating chamber-specific responses to ES, LV pressure was recorded during swimming. Swimming initiated immediate increases in heart rates (HRs), systolic pressure, dP/dtmax and -dP/dtmin, which remained stable for ∼45 min. LV end-diastolic pressures (LVEDP) increased to ≥45 mmHg during the first 10 min and subsequently declined. After 45 min, HR and -dP/dtmin declined, which correlated with gradual elevations in LVEDP (to ∼45 mmHg) as mice approached exhaustion. All parameters rapidly normalized postexercise. Consistent with human studies, our findings demonstrate a disproportionate negative impact of acute exhaustive exercise on RVs that persisted for at least 24 h. We speculate that the differential effects of exhaustive exercise on the ventricles arise from a ∼2-fold greater hemodynamic load in the RV than in LV originating from profound elevations in LVEDPs as mice approach exhaustion.NEW & NOTEWORTHY Acute exhaustive exercise differentially impacts the right ventricle (RV) versus left ventricle (LV), yet the underlying hemodynamic basis remains unclear. Using pressure-volume analyses and pressure-telemetry implantation in mice, we confirmed a marked disproportionate and persistent negative impact of exhaustive exercise on the RV. These differences in responses of the ventricles to exhaustive exercise are of clinical relevance, reflecting ∼2-fold greater hemodynamic RV loads versus LVs arising from massive (∼45 mmHg) increases in LV end-diastolic pressures at exhaustion.

Transcriptomic Bioinformatic Analyses of Atria Uncover Involvement of Pathways Related to Strain and Post-translational Modification of Collagen in Increased Atrial Fibrillation Vulnerability in Intensely Exercised Mice.

Atrial Fibrillation (AF) is the most common supraventricular tachyarrhythmia that is typically associated with cardiovascular disease (CVD) and poor cardiovascular health. Paradoxically, endurance athletes are also at risk for AF. While it is well-established that persistent AF is associated with atrial fibrosis, hypertrophy and inflammation, intensely exercised mice showed similar adverse atrial changes and increased AF vulnerability, which required tumor necrosis factor (TNF) signaling, even though ventricular structure and function improved. To identify some of the molecular factors underlying the chamber-specific and TNF-dependent atrial changes induced by exercise, we performed transcriptome analyses of hearts from wild-type and TNF-knockout mice following exercise for 2 days, 2 or 6 weeks of exercise. Consistent with the central role of atrial stretch arising from elevated venous pressure in AF promotion, all 3 time points were associated with differential regulation of genes in atria linked to mechanosensing (focal adhesion kinase, integrins and cell-cell communications), extracellular matrix (ECM) and TNF pathways, with TNF appearing to play a permissive, rather than causal, role in gene changes. Importantly, mechanosensing/ECM genes were only enriched, along with tubulin- and hypertrophy-related genes after 2 days of exercise while being downregulated at 2 and 6 weeks, suggesting that early reactive strain-dependent remodeling with exercise yields to compensatory adjustments. Moreover, at the later time points, there was also downregulation of both collagen genes and genes involved in collagen turnover, a pattern mirroring aging-related fibrosis. By comparison, twofold fewer genes were differentially regulated in ventricles vs. atria, independently of TNF. Our findings reveal that exercise promotes TNF-dependent atrial transcriptome remodeling of ECM/mechanosensing pathways, consistent with increased preload and atrial stretch seen with exercise. We propose that similar preload-dependent mechanisms are responsible for atrial changes and AF in both CVD patients and athletes.

Phosphodiesterase type 3A (PDE3A), but not type 3B (PDE3B), contributes to the adverse cardiac remodeling induced by pressure overload.

Phosphodiesterase type 3 (PDE3) inhibitors block the cAMP hydrolyzing activity of both PDE3 isoforms, PDE3A and PDE3B, which have distinct roles in the heart. Although PDE3 inhibitors improve cardiac function in heart disease patients, they also increase mortality. Nevertheless, PDE3 inhibitors can provide benefit to non-ischemic heart disease patients and are used extensively to treat heart failure in dogs. Since the isoform-dependence of the complex cardiac actions of PDE3 inhibition in diseased hearts remains unknown, we assessed the effects of PDE3 inhibitors as well as gene ablation of PDE3A or PDEB in mice following the induction of non-ischemic heart disease by pressure-overload with transverse-aortic constriction (TAC). As expected, after 6 weeks of TAC, mice exhibited left ventricular contractile dysfunction, dilation, hypertrophy and interstitial fibrosis, in association with increased macrophage numbers, activation of p38 MAPK and elevated PDE3 activity. Chronic PDE3 inhibition with milrinone (MIL), at doses that did not affect either cardiac contractility or arterial blood pressure, profoundly attenuated the adverse ventricular remodeling, reduced macrophage number and diminished p38-MAPK activation induced by TAC. Surprisingly, whole-body ablation of PDE3A, but not PDE3B, provided similar protection against TAC-induced adverse ventricular remodeling, and the addition of MIL to mice lacking PDE3A provided no further protection. Our results support the conclusion that PDE3A plays an important role in adverse cardiac remodeling induced by chronic pressure overload in mice, although the underlying biochemical mechanisms remain to be fully elucidated. The implications of this conclusion on the clinical use of PDE3 inhibitors are discussed.

Inhibition of soluble TNFα prevents adverse atrial remodeling and atrial arrhythmia susceptibility induced in mice by endurance exercise.

Intense endurance exercise is linked to atrial fibrillation (AF). We established previously that interventions that simultaneously interfere with TNFα signaling, mediated via both the enzymatically liberated soluble and membrane-bound forms of TNFα, prevent atrial remodeling and AF vulnerability in exercised mice. To investigate which signaling modality underlies this protection, we treated exercised mice with XPRO®1595, a selective dominant-negative inhibitor of solTNFα. In male CD1 mice, 6 weeks of intense swim exercise induced reductions in heart rate, increased cardiac vagal tone, left ventricular (LV) dilation and enhanced LV function. By contrast, exercise induced hypertrophy, fibrosis, and increased inflammatory cell infiltrates in atria, and these changes were associated with increased AF susceptibility in isolated atria as well as mice, with and without parasympathetic nerve blockade. Although XPRO treatment had no effect on the beneficial physiological changes induced by exercise, it protected against adverse atrial changes as well as AF susceptibility. Our results establish that soluble TNFα is required for exercise-induced increases in AF vulnerability, which is linked to fibrosis, inflammation, and enlargement of the atria, but largely independent of changes in vagal tone.

MicroRNA 199a-5p induces apoptosis by targeting JunB.

MicroRNAs participate in a variety of physiological and pathophysiological processes in various organs including the heart. Our previous work revealed that the level of miR-199a-5p was significantly higher in failing hearts than in control hearts. However, whether it is associated with the progression of heart failure (HF) and mediates cardiomyocyte apoptosis remained unclear. In the present study, we used various biochemical and molecular biological approaches to investigate the changes in miR-199a-5p levels in failing hearts in a rat model induced by acute myocardial infarction. We found that miR-199a-5p levels in the heart increased with the progression of HF, and overexpression of miR-199a-5p significantly increased apoptosis in untreated H9C2 cells and potentiated angiotensin II-induced apoptosis. Thus, our results indicate that miR-199a-5p is involved in the progression of HF and mediates cardiomyocyte apoptosis. We also confirmed that JunB, a member of the activator protein-1 transcription factor family, is one of direct targets of miR-199a-5p via a dual-luciferase reporter assay and mutagenesis on the 3' untranslated region of the JunB gene. Consistent with the above findings, overexpression of JunB in H9c2 cells suppressed cell apoptosis. Based on our findings, miR-199a-5p induces apoptosis by targeting JunB.

Atorvastatin Attenuates Metabolic Remodeling in Ischemic Myocardium through the Downregulation of UCP2 Expression.

Uncoupling protein 2 (UCP2) is primarily expressed in the myocardium and is closely related to myocardial ischemia/reperfusion injury and myocardial metabolism. To explore the effects and the mechanisms of UCP2 on atorvastatin-mediated myocardium protection, the rat model of myocardial ischemia was established by ligation of the left anterior descending coronary arteries (LADs). The rats were divided into the sham operation (SO) group, myocardial infarction (MI) group and MI-atorvastatin group. The study that atorvastatin reduced myocardial remodeling and improved the disturbed myocardial energy metabolism after MI. Furthermore, the mechanisms of myocardial metabolic remodeling affected by atorvastatin were explored. The atorvastatin group showed a significantly decreased expression of UCP2 mRNA and protein. Furthermore, the primary rat cardiomyocytes were cultured and treated with angiotensin II (Ang II) to induce cardiomyocyte hypertrophy. The results showed that in the atorvastatin group, the surface area of the cardiomyocytes, the total protein content per unit of cells, and the expression of the UCP2 protein were significantly decreased. These data suggested that atorvastatin significantly attenuated the myocardial remodeling by downregulating the expression of UCP2 that was found to improve the myocardial energy metabolism, inhibit myocardial hypertrophy, and eventually reduce myocardial remodeling.

Differential microRNA Expression and Regulation in the Rat Model of Post-Infarction Heart Failure.

BACKGROUND: Heart failure is a complex end stage of various cardiovascular diseases with a poor prognosis, and the mechanisms for development and progression of heart failure have always been a hot point. However, the molecular mechanisms underlying the post transcriptional regulation of heart failure have not been fully elucidated. Current data suggest that microRNAs (miRNAs) are involved in the pathogenesis of heart failure and could serve as a new biomarker, but the precise regulatory mechanisms are still unclear. METHODS: The differential miRNA profile in a rat model of post-infarction heart failure was determined using high throughout sequencing and analyzed through bioinformatics approaches. The results were validated using qRT-PCR for 8 selected miRNAs. Then the expression patterns of 4 miRNAs were analyzed in different periods after myocardial infarction. Finally, gain- and loss-of-function experiments of rno-miR-122-5p and rno-miR-184 were analyzed in H2O2 treated H9c2 cells. RESULTS: In the heart failure sample, 78 miRNAs were significantly upregulated and 28 were downregulated compared to the controls. GO and KEGG pathway analysis further indicated the likely roles of these miRNAs in heart failure. Time-course analysis revealed different expression patterns of 4 miRNAs: rno-miR-122-5p, rno-miR-199a-5p, rno-miR-184 and rno-miR-208a-3p. Additionally, rno-miR-122-5p and rno-miR-184 were proved to promote apoptosis in vitro. CONCLUSIONS: Differential profile and expression patterns of miRNAs in the rats model of post-infarction heart failure were found, and the pro-apoptotic roles of rno-miR-122-5p and rno-miR-184 were revealed. These findings may provide a novel way that may assist in heart failure diagnosis and treatment.

Warfarin continuation vs interruption during procedures of cardiac rhythm devices: A Meta-analysis of randomized controlled trials.

To compare the safetyand efficacy of warfarin treatment continuation and heparin-bridging therapy during cardiac rhythm device (CRD) implantation in patients chronically treated with anticoagulants.We performed a search and analysis of peer-reviewed studies Four randomized controlled trials (RCTs)were included in our analysis with 941 patients. The bleeding risk in patients continuing warfarin perioperatively was lower than those interrupting warfarin and using a heparin-bridge (RD -0.08, 95% CI -0.17 to 0.02, p< 0.05). There was no significant difference in ischaemic risk between two methods (RD 0, 95% CI -0.01 to 0.02, p=1.00). Hence, in patients undergoing long-term warfarin therapy, continuation of warfarin treatment is a safe and efficacious perioperative strategy for during CRD implantations, while interruption of warfarin with a heparin bridge may increase the bleeding risk in these patients.

The human ATF1 rs11169571 polymorphism increases essential hypertension risk through modifying miRNA binding.

Activating transcription factor 1 (ATF1) may be involved in essential hypertension (EH) by induction of NADPH oxidase 1 (NOX1) and radical oxygen species (ROSs) production. Abnormal expression of ATF1 was found in EH in previous microarray analysis. Here we tested whether a single nucleotide polymorphism (SNP) located in the 3'-untranslated region (3'UTR) of ATF1 was associated with EH susceptibility by affecting microRNA (miRNA) binding. In silico analysis indicated that rs11169571 (T>C) was a candidate SNP to modulate miRNA: ATF1 mRNA complex, with the greatest changed energy for hsa-miR-1283, and the luciferase reporter analysis showed that miR-1283 inhibited the activity of the reporter vector carrying -T allele, but not the -C allele. In addition, inhibition of miR-1283 in HA-VSMCs enhanced the expression of ATF1 mRNA as well as the ROS levels. Further case-control study showed that rs11169571 was significantly associated with increased risk of EH. Finally, we observed an increased ATF1 protein level in peripheral blood of EH patients with CC carriers compared to TT carriers of rs11169571, with an intermediate ATF1 level in TC carriers. These results suggested that rs11169571 of ATF1 gene may be associated with EH, and the SNP-modified posttranscriptional gene regulation by miRNAs could be a potentially pathogenetic mechanism of EH.

Association of single nucleotide polymorphisms in the 3'UTR of ERAP1 gene with essential hypertension in the Northeastern Han Chinese.

Endoplasmic reticulum aminopeptidase 1 (ERAP1) may be involved in blood pressure regulation by inactivation of angiotensin II and generation of bradykinin. Our previous study with cDNA microarray indicated that the expression of ERAP1 is down-regulated in essential hypertension (EH) patients. Since the 3'untranslated region (3'UTR) is known to play an important role in the post-transcriptional regulation by influencing the stability and translation process of mRNA, the present study aims to identify single nucleotide polymorphisms (SNPs) in the 3'UTR of ERAP1 gene in a case-control study among the Northeastern Han Chinese through PCR-sequencing, and analyze the association with EH. Our results further verified the lower expression level of ERAP1 in the peripheral blood cells in patients with EH (917.12±517.57 vs. 1506.59±1214.09pg/mL, P=0.011). Four SNPs, 3'UTR-761G>A, 3'UTR-787C>T, 3'UTR-1008A>C and 3'UTR-1055A>G, were identified in the 3'UTR of ERAP1. 3'UTR-1008A>C and 3'UTR-1055A>G were in almost complete linkage disequilibrium. Association analysis showed that the genotypic and allelic frequencies of 3'UTR-1008A>C and 3'UTR-1055A>G were significantly different between EH and the control groups. Logistic regression and haplotypic analysis indicated that alleles of E20-1037C and E20-1084G as well as haplotype of C-G were the risk factors of EH (P<0.05). Subgroup analysis performed by age suggested that the frequencies of genotype and allele of 3'UTR-1008A>C and 3'UTR-1055A>G as well as the haplotypes C-G and A-A were significantly different between EH and the control in the younger group (<50), but not in the older group (≥50). Younger population with the 3'UTR-1008CC and/or 3'UTR-1055GG genotypes also tended to have higher blood pressure, especially the diastolic blood pressure. In conclusion, the 3'UTR-1008A>C and 3'UTR-1055A>G polymorphisms of ERAP1 gene were associated with EH, especially in the younger population, and the haplotype C-G could be the independent marker of EH.