BRD4 as a therapeutic target for atrial fibrosis and atrial fibrillation.

OBJECTIVE: This study aimed to elucidate the molecular mechanisms by which BRD4 play a role in atrial fibrillation (AF). METHODS AND RESULTS: We used a discovery-driven approach to detect BRD4 expression in the atria of patients with AF and in various murine models of atrial fibrosis. We used a BRD4 inhibitor (JQ1) and atrial fibroblast (aFB)-specific BRD4-knockout mice to elucidate the role of BRD4 in AF. We further examined the underlying mechanisms using RNA-seq and ChIP-seq analyses in vitro, to identify key downstream targets of BRD4. We found that BRD4 expression is significantly increased in patients with AF, with accompanying atrial fibrosis and aFB differentiation. We showed that JQ1 treatment and shRNA-based molecular silencing of BRD4 blocked ANG-II-induced extracellular matrix production and cell-cycle progression in aFBs. BRD4-related RNA-seq and ChIP-seq analyses in aFBs demonstrated enrichment of a subset of promoters related to the expression of profibrotic and proliferation-related genes. The pharmacological inhibition of BRD4 in vivo or in aFB-specific BRD4-knockout in mice limited ANG-II-induced atrial fibrosis, atrial enlargement, and AF susceptibility. CONCLUSION: Our findings suggest that BRD4 plays a key role in pathological AF, at least partially by activating aFB proliferation and ECM synthesis. This study provides mechanistic insights into the development of BRD4 inhibitors as targeted antiarrhythmic therapies.

Downregulation of MYBL1 in endothelial cells contributes to atherosclerosis by repressing PLEKHM1-inducing autophagy.

MYBL1 is a strong transcriptional activator involved in the cell signaling. However, there is no systematic study on the role of MYBL1 in atherosclerosis. The aim of this study is to elucidate the role and mechanism of MYBL1 in atherosclerosis. GSE28829, GSE43292 and GSE41571 were downloaded from NCBI for differentially expressed analysis. The expression levels of MYBL1 in atherosclerotic plaque tissue and normal vessels were detected by qRT-PCR, Western blot and Immunohistochemistry. Transwell and CCK-8 were used to detect the migration and proliferation of HUVECs after silencing MYBL1. RNA-seq, Western blot, qRT-PCR, Luciferase reporter system, Immunofluorescence, Flow cytometry, ChIP and CO-IP were used to study the role and mechanism of MYBL1 in atherosclerosis. The microarray data of GSE28829, GSE43292, and GSE41571 were analyzed and intersected, and then MYBL1 were verified. MYBL1 was down-regulated in atherosclerotic plaque tissue. After silencing of MYBL1, HUVECs were damaged, and their migration and proliferation abilities were weakened. Overexpression of MYBL1 significantly enhanced the migration and proliferation of HUVECs. MYBL1 knockdown induced abnormal autophagy in HUVEC cells, suggesting that MYBL1 was involved in the regulation of HUVECs through autophagy. Mechanistic studies showed that MYBL1 knockdown inhibited autophagosome and lysosomal fusion in HUVECs by inhibiting PLEKHM1, thereby exacerbating atherosclerosis. Furthermore, MYBL1 was found to repress lipid accumulation in HUVECs after oxLDL treatment. MYBL1 knockdown in HUVECs was involved in atherosclerosis by inhibiting PLEKHM1-induced autophagy, which provided a novel target of therapy for atherosclerosis.

A Common East Asian aldehyde dehydrogenase 2*2 variant promotes ventricular arrhythmia with chronic light-to-moderate alcohol use in mice.

Chronic heavy alcohol use is associated with lethal arrhythmias. Whether common East Asian-specific aldehyde dehydrogenase deficiency (ALDH2*2) contributes to arrhythmogenesis caused by low level alcohol use remains unclear. Here we show 59 habitual alcohol users carrying ALDH2 rs671 have longer QT interval (corrected) and higher ventricular tachyarrhythmia events compared with 137 ALDH2 wild-type (Wt) habitual alcohol users and 57 alcohol non-users. Notably, we observe QT prolongation and a higher risk of premature ventricular contractions among human ALDH2 variants showing habitual light-to-moderate alcohol consumption. We recapitulate a human electrophysiological QT prolongation phenotype using a mouse ALDH2*2 knock-in (KI) model treated with 4% ethanol, which shows markedly reduced total amount of connexin43 albeit increased lateralization accompanied by markedly downregulated sarcolemmal Nav1.5, Kv1.4 and Kv4.2 expressions compared to EtOH-treated Wt mice. Whole-cell patch-clamps reveal a more pronounced action potential prolongation in EtOH-treated ALDH2*2 KI mice. By programmed electrical stimulation, rotors are only provokable in EtOH-treated ALDH2*2 KI mice along with higher number and duration of ventricular arrhythmia episodes. The present research helps formulate safe alcohol drinking guideline for ALDH2 deficient population and develop novel protective agents for these subjects.

Immediate electrophysiological characteristics following modified thoracoscopic ablation via unilateral approach for non-valvular atrial fibrillation.

BACKGROUND: Thoracoscopic ablation has emerged as an effective therapy for patients with long-standing persistent Atrial fibrillation (LsPAF). We aimed to investigate the immediate electrophysiological characteristics following modified ablation with 3 circular and 3 linear lesions in the thoracoscopic procedure via a unilateral approach. METHODS: Between May 2015 and October 2018, 40 patients underwent the one-stage hybrid procedure for LsPAF. Isolation of the pulmonary veins (PV) and left atrium posterior wall (LAPW), excision of the left atrial appendage (LAA), and high-density endocardial mapping and individualized percutaneous catheter ablation for AF termination were performed. RESULTS: The modified thoracoscopic procedure may enable successful PV and LAPW isolation and LAA removal. Endocardial electrophysiological examination showed 6 out of 40 (15%) patients with a right PV gap, 3 (7.5%) patients with incomplete roof lesions, and 8 (20%) patients with incomplete Dallas lesions. A total of 44 driving areas were mapped and ablated. Thirty-five patients achieved procedural AF termination. After a mean follow-up period of 26 months, the success rate of a single procedure was 85%. Cox regression analysis demonstrated that the failure of procedural AF termination may be a risk factor in atrial tachyarrhythmia recurrence. DISCUSSION: Endocardial electrophysiological examination is a necessary partner to thoracoscopic ablation. Our modified thoracoscopic ablation and driving areas-based ablation contribute to high rates of procedural AF termination, which may lead to reduced recurrence rate. The hybrid procedure may be an effective strategy for the management of LsPAF.

Effects and Mechanisms of Cutting Upper Thoracic Sympathetic Trunk on Ventricular Rate in Ambulatory Canines with Persistent Atrial Fibrillation.

OBJECTIVE: The purpose is to observe the effects and neural mechanism of cutting upper thoracic sympathetic trunk (TST) on the ventricular rate (VR) during persistent atrial fibrillation (AF). METHODS: Twelve beagle dogs were halving to the control group and experimental group, 6 dogs for each group. Both groups were performed with left atrial rapid pacing (600 beats/min) to induce sustained AF. The experimental group underwent cutting upper TST after a sustained AF model was established, while the control group received thoracotomy without cutting TST. Bilateral stellate ganglion (SG) and left atrial myocardium were harvested for tyrosine-hydroxylase (TH) immunohistochemical staining. RESULTS: After cutting upper TST for 30 minutes, the average VR was 121.5 ± 8.7 bpm (95% CI, 114.8 to 128.0) in the experimental group, which was significantly slower than that of the control group (144.5 ± 4.2 bpm (95% CI, 141.5 to 148.0)) (P < 0.001). After cutting upper TST for 1 month, the average VR of the experimental group (106.5 ± 4.9 bpm (95% CI, 102.0 to 110.0)) was also significantly slower versus that of the control group (139.2 ± 5.6 bpm (95% CI, 135.0 to 143.8)) (P < 0.001). Compared with the control group, both left stellate ganglion (LSG) and right stellate ganglion (RSG) of the experimental group caused neural remodeling characterized by decreased ganglionic cell density and reduced TH staining. TH-positive component was significantly decreased in the left atrium of the experimental group compared with the control group. CONCLUSIONS: Cutting upper TST could reduce fast VR during persistent AF. Cutting upper TST induced bilateral SG neural remodeling and reduced sympathetic nerve density in the left atrium, which could contribute to the underlying mechanism of VR control during AF.

Sesn2 attenuates the damage of endothelial progenitor cells induced by angiotensin II through regulating the Keap1/Nrf2 signal pathway.

Endothelial progenitor cell (EPC) dysfunction is an important physiopathological mechanism in the dynamics of the formation of atherosclerosis. It has been reported that angiotensin II (Ang-II) damages the function of EPCs in atherosclerotic plaque through induction of oxidative stress. Sestrin 2 (Sesn2) serves as an antioxidant role in oxidative stress, however, the exact mechanisms underlying the dynamics of how Sesn2 may factor into EPCs after Ang-II treatments needs to be illustrated. We isolated EPCs from human umbilical cord blood samples and treated with Ang-II. Western blotting, qRT-PCR, transwell assays, immunofluorescence and so on were used to investigate the mechanisms underlying the roles of Sesn2 in EPCs treated with Ang-II. Ang-II was found to promote the apoptosis of EPCs as well as inhibited the mRNA and protein expression of Sesn2. Upregulation of Sesn2 attenuated the negative effect of Ang-II. Sesn2 increased the protein expression of Nrf2 by enhancing P62-dependent autophagy. Silencing of Nrf2 enhanced the degree of apoptosis of EPCs as well as resulted in the impairment of EPC functions through inducing the promotion of (reactive oxygen species) ROS production. Our study results indicated that Sesn2 facilitated the viability of EPCs After treatment with Ang-II, as well as provided a potential therapeutic target to alleviate the progression of atherosclerosis.

The Mei mini-maze procedure.

Atrial fibrillation is a common clinical arrhythmia with high morbidity and a risk of stroke. The Cox-maze IV procedure that uses radiofrequency energy for ablation is established as an effective way to eliminate atrial fibrillation. Compared to the Cox-maze IV procedure, the video-assisted Wolf mini-maze procedure is associated with reduced surgical trauma, but still requires bilateral thoracotomies, and the ablation line connecting the right and left pulmonary vein isolations cannot be created with a bipolar ablation clamp. We have developed a novel video-assisted mini-maze technique that uses a unilateral (left chest) thoracoscopic approach (the Mei mini-maze procedure).

MicroRNA-15a inhibition protects against hypoxia/reoxygenation-induced apoptosis of cardiomyocytes by targeting mothers against decapentaplegic homolog 7.

Myocardial ischemia/reperfusion (I/R) injury is a major pathological process in coronary heart disease and cardiac surgery, and is associated with aberrant microRNA (miR) expression. Previous studies have demonstrated that inhibition of miR-15a expression may ameliorate I/R­induced myocardial injury. In the present study, the potential role and underlying mechanism of miR­15a in hypoxia/reoxygenation­induced apoptosis of cardiomyocytes was investigated. Myocardial I/R was simulated in cultured H9c2 cells by 24 h hypoxia followed by 24 h reoxygenation. Using recombinant lentivirus vectors, the inhibition of miR­15a was indicated to significantly reduce cardiomyocyte apoptosis and release of lactate dehydrogenase and malondialdehyde. Conversely, upregulated miR­15a expression was pro­apoptotic. Mothers against decapentaplegic homolog 7 (SMAD7) was identified by bioinformatics analysis as a potential target of miR­15a. Luciferase reporter assays and western blotting for endogenous SMAD7 protein indicated that miR­15a inhibited SMAD7 expression via its 3'­untranslated region. Nuclear levels of nuclear factor­κB (NF­κB) p65 were increased by miR­15a expression and decreased by miR­15a inhibition, which is consistent with the possibility that the inhibition of SMAD7 by miR-15a results in NF­κB activation. These findings suggested that the therapeutic effects of miR­15a inhibition on I/R injury may potentially be explained by its ability to release SMAD­7­dependent NF­κB inhibition. This may provide evidence for miR­15a as a potential therapeutic target for the treatment of cardiac I/R injury.

Coarctation of the aorta associated with agenesis of left common carotid artery and left subclavian artery.

We describe the case of a 10-year-old boy with coarctation of the aorta complicated by innominate artery stenosis and agenesis of left common carotid artery and left subclavian artery. The patient was treated with an interposition graft between the ascending and descending aorta. The right subclavian was revascularized with another graft from the interposition graft to the distal right subclavian. This is a rare case of the combination of coarctation of the aorta and other vascular malformations.

Protective Effects of L-Malate against Myocardial Ischemia/Reperfusion Injury in Rats.

Objective. To investigate the protective effects of L-malate against myocardial ischemia/reperfusion (I/R) injury in rats. Methods. Male Sprague-Dawley rats were randomly assigned to the following groups: sham (sham), an ischemia/reperfusion (I/R) model group (model), an DMF pretreated group (DMF), and 5 L-malate pretreated groups (15, 60, 120, 240, or 480 mg/kg, gavage) before inducing myocardial ischemia. Plasma LDH, cTn-I, TNF-α, hs-CRP, SOD, and GSH-PX were measured 3 h later I/R. Areas of myocardial infarction were measured; hemodynamic parameters during I/R were recorded. Hearts were harvested and Western blot was used to quantify Nrf2, Keap1, HO-1, and NQO-1 expression in the myocardium. Results. L-malate significantly reduced LDH and cTn-I release, reduced myocardial infarct size, inhibited expression of inflammatory cytokines, and partially preserved heart function, as well as increasing antioxidant activity after myocardial I/R injury. Western blot confirmed that L-malate reduced Kelch-like ECH-associated protein 1 in ischemic myocardial tissue, upregulated expression of Nrf2 and Nrf2 nuclear translocation, and increased expression of heme oxygenase-1 and NAD(P)H: quinone oxidoreductase 1, which are major targets of Nrf2. Conclusions. L-malate may protect against myocardial I/R injury in rats and this may be associated with activation of the Nrf2/Keap1 antioxidant pathway.

Continuous vagal nerve stimulation affects atrial neural remodeling and reduces atrial fibrillation inducibility in rabbits.

BACKGROUND: The effects of continuous vagal nerve stimulation (VNS) on atrial neural remodeling during atrial fibrillation (AF) remain unclear. OBJECTIVE: To test the hypothesis that VNS affects atrial neural remodeling and reduces AF inducibility. METHODS: Twenty rabbits were randomly divided into two groups: rapid atrial pacing (RAP) group and RAP with VNS group. AF inducibility studies and atrial histologic analyses were performed after 4 weeks. RESULTS: Five rabbits of RAP group (5/10) in the RAP group developed sustained AF. None of rabbits in RAP with VNS group had developed AF. The incidence of sustained AF in VNS group was significant lower than that in rapid pacing group (P<.01). Treatment with VNS resulted in a significant reduction in atrial neural remodeling and AF duration (P<.01). CONCLUSIONS: Atrial neural remodeling plays an important role in the initiation and maintenance of AF. Modulating autonomic nerve function with VNS can contribute to AF control.

Analysis of the Synergistic Effects of Fasting Plasma Glucose and Hypertension on Cardiovascular Autonomic Neuropathy.

BACKGROUND: The purpose of this study was to evaluate the associations of fasting plasma glucose (FPG) and hypertension (HTN) with cardiovascular autonomic neuropathy (CAN) and to estimate the extent to which the synergistic effects of FPG and HTN affect outcomes in a Chinese population. METHOD: We conducted a large-scale, population-based study to analyze the association and interaction of the two factors with CAN in a sample of 2,092 Chinese people. Univariate and multiple linear regression (MLR) analyses were employed to detect these relationships. Interaction on an additive scale can be calculated by using the relative excess risk due to interaction, the proportion attributable to interaction (AP), and the synergy index (S). RESULT: After adjusting for confounding factors, MLR showed that FPG and HTN were independently associated with CAN (p < 0.001 for both). A significant synergistic effect of FPG and HTN on CAN was detected (p = 0.046, RETI = 0.733, 95% CI 0.059-1.450; AP = 0.167, 95% CI -0.033 to 0.367; S = 1.275, 95% CI 0.140-2.410). CONCLUSION: Our findings suggest that FPG and HTN are independently associated with CAN, and they offer evidence to support the hypothesis that FPG and HTN have synergistic effects that influence the progression of CAN.