Zbtb16 increases susceptibility of atrial fibrillation in type 2 diabetic mice via Txnip-Trx2 signaling.

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia, and recent epidemiological studies suggested type 2 diabetes mellitus (T2DM) is an independent risk factor for the development of AF. Zinc finger and BTB (broad-complex, tram-track and bric-a-brac) domain containing 16 (Zbtb16) serve as transcriptional factors to regulate many biological processes. However, the potential effects of Zbtb16 in AF under T2DM condition remain unclear. Here, we reported that db/db mice displayed higher AF vulnerability and Zbtb16 was identified as the most significantly enriched gene by RNA sequencing (RNA-seq) analysis in atrium. In addition, thioredoxin interacting protein (Txnip) was distinguished as the key downstream gene of Zbtb16 by Cleavage Under Targets and Tagmentation (CUT&Tag) assay. Mechanistically, increased Txnip combined with thioredoxin 2 (Trx2) in mitochondrion induced excess reactive oxygen species (ROS) release, calcium/calmodulin-dependent protein kinase II (CaMKII) overactivation, and spontaneous Ca2+ waves (SCWs) occurrence, which could be inhibited through atrial-specific knockdown (KD) of Zbtb16 or Txnip by adeno-associated virus 9 (AAV9) or Mito-TEMPO treatment. High glucose (HG)-treated HL-1 cells were used to mimic the setting of diabetic in vitro. Zbtb16-Txnip-Trx2 signaling-induced excess ROS release and CaMKII activation were also verified in HL-1 cells under HG condition. Furthermore, atrial-specific Zbtb16 or Txnip-KD reduced incidence and duration of AF in db/db mice. Altogether, we demonstrated that interrupting Zbtb16-Txnip-Trx2 signaling in atrium could decrease AF susceptibility via reducing ROS release and CaMKII activation in the setting of T2DM.

Adding six short lines on pulmonary vein isolation circumferences reduces recurrence of paroxysmal atrial fibrillation: Results from a multicenter, single-blind, randomized trial.

BACKGROUND: Pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) is associated with a non-negligible long-term recurrence rate. OBJECTIVES: The purpose of this study was to investigate whether PVI combined with 6 short ablation lines on the PVI circumferences (PVI+6L group) yields higher success rates than PVI alone (PVI group). METHODS: In this multicenter, single-blind, randomized trial, a total of 390 patients with paroxysmal AF were randomly assigned to the PVI group (n = 193) or the PVI+6L group (n = 197). The primary endpoint was freedom from AF/atrial tachycardia recurrence between 91 and 365 days. Secondary endpoints included AF burden, procedural parameters, and complications. RESULTS: Freedom from atrial tachyarrhythmia was achieved in 160 of 197 patients (81.2%) in the PVI+6L group and 142 of 193 patients (73.6%) in the PVI group (hazard ratio 0.61; 95% confidence interval 0.39-0.97; P = .040). Mean AF burden tended to be lower in the PVI+6L group compared to the PVI group (1.95% vs 0.53%, P = .097). Procedural and ablation times were slightly longer in the PVI+6L group than in the PVI group (130 ± 25 minutes vs 121 ± 28 minutes; P = .002; and 46 ± 14 minutes vs 41 ± 16 minutes, P = .001, respectively). X-ray exposure was similar (60 ± 54 seconds vs 61 ± 60 seconds; P = .964). Complications occurred in 3 patients (1.6%) in the PVI group and 3 patients (1.5%) in the PVI+6L group. CONCLUSION: In patients with paroxysmal AF undergoing catheter ablation, adding 6 short ablation lines on the PVI circumferences could reduce the AF recurrence rate.

Loss of nocturnal dipping pattern of skin sympathetic nerve activity during and following an extended-duration work shift in residents in training.

BACKGROUND: Extended-duration work shifts (EDWSs) might affect the health of physician residents, causing autonomic alteration. Skin sympathetic nerve activity (SKNA) recorded by noninvasive neuro-electrocardiography (neuECG) is used to estimate cardiac sympathetic tone. In this study, we aim to evaluate the impact of EDWSs on nocturnal SKNA assessed in resident doctors. METHODS: Twenty-four residents working EDWSs and 12 PhD students not working nightshift schedules were prospectively recruited. The neuECG was performed between 12 am and 6 am for 5 consecutive nights. SKNA was filtered from neuECG recorded signals. The questionnaires regarding work stress and sleep quality, blood pressure, and salivary alpha-amylase and cortisol levels were administered. RESULTS: The hours of weekly working and sleep opportunities were similar between residents and students, while residents reported more work stress and worse sleep quality. In residents, SKNA at 6 am (SKNA6am) was significantly higher than SKNA2am during the precall night, revealing a dipping pattern. However, the SKNA dipping disappeared during the on-call night and prominently flattened during the first postcall night, the full recovery of which was delayed until the second postcall nights. The morning blood pressure and salivary alpha-amylase and cortisol levels were similar between the precall and postcall days. In contrast, SKNA in students exhibited a constant dipping profile for all recorded nights. CONCLUSIONS: In healthy young adults, SKNA presents a dip night. The SKNA dip is impaired by working a nightshift, with a delayed recovery. The neuECG might serve as a useful tool to detect subclinical autonomic disturbances in shiftworkers.

Double-blind, placebo-controlled randomised clinical trial to evaluate the effect of ASPIRIN discontinuation after left atrial appendage occlusion in atrial fibrillation: protocol of the ASPIRIN LAAO trial.

INTRODUCTION: It is the common clinical practice to prescribe indefinite aspirin for patients with non-valvular atrial fibrillation (NVAF) post left atrial appendage occlusion (LAAO). However, aspirin as a primary prevention strategy for cardiovascular diseases has recently been challenged due to increased risk of bleeding. Therefore, aspirin discontinuation after LAAO in atrial fibrillation (ASPIRIN LAAO) trial is designed to assess the uncertainty about the risks and benefits of discontinuing aspirin therapy at 6 months postimplantation with a Watchman LAAO device in NVAF patients. METHODS AND ANALYSIS: The ASPIRIN LAAO study is a prospective, multicentre, randomised, double-blinded, placebo-controlled non-inferiority trial. Patients implanted with a Watchman device within 6 months prior to enrollment and without pre-existing conditions requiring long-term aspirin therapy according to current guidelines are eligible for participating the trial. Subjects will be randomised in a 1:1 allocation ratio to either the Aspirin group (aspirin 100 mg/day) or the control group (placebo) at 6 months postimplantation. A total of 1120 subjects will be enrolled from 12 investigational sites in China. The primary composite endpoint is stroke, systemic embolism, cardiovascular/unexplained death, major bleeding, acute coronary syndrome and coronary or periphery artery disease requiring revascularisation at 24 months. Follow-up visits are scheduled at 6 and 12 months and then every 12 months until 24 months after the last patient recruitment. ETHICS AND DISSEMINATION: Ethics approval was obtained from the Ethics Committee of Xinhua Hospital, Shanghai, China (reference number XHEC-C-2018-065-5). The protocol is also submitted and approved by the institutional Ethics Committee at each participating centre. Results are expected in 2024 and will be disseminated through peer-reviewed journals and presentations at national and international conferences. TRIAL REGISTRATION NUMBER: NCT03821883.

The regulation of the small-conductance calcium-activated potassium current and the mechanisms of sex dimorphism in J wave syndrome.

Apamin-sensitive small-conductance calcium-activated potassium (SK) current (IKAS) plays an important role in cardiac repolarization under a variety of physiological and pathological conditions. The regulation of cardiac IKAS relies on SK channel expression, intracellular Ca2+, and interaction between SK channel and intracellular Ca2+. IKAS activation participates in multiple types of arrhythmias, including atrial fibrillation, ventricular tachyarrhythmias, and automaticity and conduction abnormality. Recently, sex dimorphisms in autonomic control have been noticed in IKAS activation, resulting in sex-differentiated action potential morphology and arrhythmogenesis. This review provides an update on the Ca2+-dependent regulation of cardiac IKAS and the role of IKAS on arrhythmias, with a special focus on sex differences in IKAS activation. We propose that sex dimorphism in autonomic control of IKAS may play a role in J wave syndrome.

Utility of Circadian Variability Patterns in Differentiating Origins of Premature Ventricular Complexes.

BACKGROUND: Premature ventricular complexes (PVCs) exhibit circadian fluctuation. We determine if PVCs of different origin exhibit specific circadian patterns. METHODS: We analyzed Holter recordings from patients with monomorphic PVCs who underwent catheter ablation. PVC circadian patterns were classified as fast-heart rate- (HR-) dependent (F-PVC), slow-HR-dependent (S-PVC), or HR-independent (I-PVC). PVC origins were determined intraprocedurally. RESULTS: In a retrospective cohort of 407 patients, F-PVC and S-PVC typically exhibited diurnal and nocturnal predominance, respectively. Despite decreased circadian fluctuation, I-PVC generally had heavier nocturnal than diurnal burden. PVCs of left anterior fascicle origin were predominantly S-PVC, while those of posterior hemibranch origin were mostly F-PVC. PVCs originating from the aortic sinus of Valsalva (ASV) were predominantly I-PVC, while most PVCs arising from the left ventricular outflow tract (LVOT) were F-PVC. Using a diurnal/nocturnal PVC burden ratio of 0.92 as the cutoff value to distinguish LVOT from ASV origin achieved 97% sensitivity and, as further verification, an accuracy of 89% (16/18) in a prospective cohort of patients with PVCs originating from either ASV or LVOT. In contrast, PVCs originating from right ventricles, such as right ventricular outflow tract, did not show distinct circadian patterns. CONCLUSIONS: The circadian patterns exhibit origin specificity for PVCs arising from left ventricles. An analysis of Holter monitoring provides useful information on PVC localization in ablation procedure planning.

Macrophages facilitate post myocardial infarction arrhythmias: roles of gap junction and KCa3.1.

Effective therapeutic targets against post-myocardial infarction (MI) arrhythmias remain to be discovered. We aimed to investigate the role of macrophages in post-MI arrhythmias. Methods: Mononuclear cell accumulation, macrophage polarization from M0 to M1 subset, and gap junction formation were analyzed in MI patients and MI mice by flow cytometry, immunofluorescence and patch clamping. Differentially expressed genes were identified by RNA sequencing. Macrophages and cardiomyocytes were cocultured in vitro, and the effects of gap junction and KCa3.1 on electrophysiological properties were assessed by patch clamping. The effects of KCa3.1 inhibition on post-MI arrhythmias were assessed by intracardiac stimulation and ambulatory electrocardiograms in vivo. Results: Percentage of pro-inflammatory mononuclear cells were significantly elevated in patients with post-MI arrhythmias compared with MI patients without arrhythmias and healthy controls (p<0.001). Macrophages formed gap junction with cardiomyocytes in MI border zones of MI patient and mice, and pro-inflammatory macrophages were significantly increased 3 days post-MI (p<0.001). RNA sequencing identified Kcnn4 as the most differentially expressed gene encoding ion channel, and the upregulation is mainly attributed to macrophage accumulation and polarization into pro-inflammatory subset. In vitro coculture experiments demonstrated that connection with M0 macrophages via gap junction slightly shortened the action potential durations (APDs) of cardiomyocytes. However, the APD90 of cardiomyocytes connected with M1 macrophages were significantly prolonged (p<0.001), which were effectively attenuated by gap junction inhibition (p=0.002), KCa3.1 inhibition (p=0.008), KCa3.1 silencing (p<0.001) and store-operated Ca2+ channel inhibition (p=0.005). In vivo results demonstrated that KCa3.1 inhibition significantly decreased the QTc durations (p=0.031), intracardiac stimulation-induced ventricular arrhythmia durations (p=0.050) and incidence of premature ventricular contractions (p=0.030) in MI mice. Conclusion: Macrophage polarization leads to APD heterogeneity and post-MI arrhythmias via gap junction and KCa3.1 activation. The results provide evidences of a novel mechanism of post-MI heterogeneous repolarization and arrhythmias, rendering macrophages and KCa3.1 to be potential therapeutic targets.

Polarization of M1 tumor associated macrophage promoted by the activation of TLR3 signal pathway.

OBJECTIVE: To investigate the correlation between activation of toll-like receptors 3 (TLR3) signaling pathway and tumor-associated macrophage and its effect on the tumor growth. METHODS: The mice Lewis lung cancer cell lines 3LL and melanoma B16H10 were used to construct the subcutaneous transplantation tumor models and then they were treated with Poly-ICLC. The curative effect was observed and then the T cell and macrophage phenotypes infiltrated in local tumor were detected by flow cytometry. After the in vitro culture of mouse bone marrow-derived macrophage, the real-time PCR and western blot were applied to detect the expression of macrophage activation markers and the activation of intracellular signaling pathways. RESULTS: The survival time of mice with brown tumor treated with Poly-ICLC significantly increased and the tumor growth was inhibited. The ratio of local tumor-infiltrated Treg decreased, while the ratio of CD8(+) T cell increased significantly. The macrophages surface CD206 expression was down-regulated while the expression of iNOS increased. The Poly-ICLC could promote the expression of M1 markers (IL-1ß, TNF-α and iNOS) in bone marrow-derived macrophage and inhibited the expression of M2 molecules (Arg-1, YM-1 and CD206). The phosphorylation level of downstream p65, TBK1 and IRF3 increased significantly. CONCLUSIONS: The Poly-ICLC can activate the TLR3 downstream signaling pathway to induce a M1 polarization of tumor associated macrophage, thereby inhibiting the tumor growth.