PIEZO1 mediates a mechanothrombotic pathway in diabetes.

Thrombosis is the leading complication of common human disorders including diabetes, coronary heart disease, and infection and remains a global health burden. Current anticoagulant therapies that target the general clotting cascade are associated with unpredictable adverse bleeding effects, because understanding of hemostasis remains incomplete. Here, using perturbational screening of patient peripheral blood samples for latent phenotypes, we identified dysregulation of the major mechanosensory ion channel Piezo1 in multiple blood lineages in patients with type 2 diabetes mellitus (T2DM). Hyperglycemia activated PIEZO1 transcription in mature blood cells and selected high Piezo1­expressing hematopoietic stem cell clones. Elevated Piezo1 activity in platelets, red blood cells, and neutrophils in T2DM triggered discrete prothrombotic cellular responses. Inhibition of Piezo1 protected against thrombosis both in human blood and in zebrafish genetic models, particularly in hyperglycemia. Our findings identify a candidate target to precisely modulate mechanically induced thrombosis in T2DM and a potential screening method to predict patient-specific risk. Ongoing remodeling of cell lineages in hematopoiesis is an integral component of thrombotic risk in T2DM, and related mechanisms may have a broader role in chronic disease.

Tbx18 promoted the conversion of human-induced pluripotent stem cell-derived cardiomyocytes into sinoatrial node-like pacemaker cells.

Sinoatrial node (SAN) pacemaker cells originate from T-box transcription factor 18 (Tbx18)-expressing progenitor cells. The present study aimed to investigate whether overexpression of human transcription factor Tbx18 could reprogram human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) into SAN-like pacemaker cells (SANLPCs) in vitro. In the study, hiPSCs were first differentiated into hiPSC-CMs through regulating the Wnt/ß-catenin pathway, then purified hiPSC-CMs were transfected by Tbx18 adenovirus (Tbx18-CMs group) or green fluorescent protein (GFP) adenovirus (GFP-CMs group). The beating frequency of the Tbx18-CMs group was significantly higher than that of the hiPSC-CMs group and GFP-CMs group. Compared with the other two groups, the expression levels of hyperpolarization-activated cyclic nucleotide-gated potassium channel isoform 4, connexin-45 in the Tbx18-CMs group were markedly upregulated, while the expressions of transcription factor NKX2.5, CX43 were significantly downregulated. Whole-cell patch-clamp results illustrated that action potential and "funny" current (If ) similar to SAN pacemaker cells could be recorded in the Tbx18-CMs group. In conclusion, this present study demonstrated that overexpression of Tbx18 promoted the conversion of hiPSC-CMs into SANLPCs.

Daphnetin Preconditioning Decreases Cardiac Injury and Susceptibility to Ventricular Arrhythmia following Ischaemia-Reperfusion through the TLR4/MyD88/NF-Κb Signalling Pathway.

BACKGROUND/AIMS: Daphnetin (7,8-dihydroxycoumarin, DAP) exhibits various bioactivities, such as anti-inflammatory and antioxidant activities. However, the role of DAP in myocardial ischaemia/reperfusion (I/R) injury and I/R-related arrhythmia is still uncertain. This study aimed to investigate the mechanisms underlying the effects of DAP on myocardial I/R injury and electrophysiological properties in vivo and in vitro. METHODS: Myocardial infarct size was measured by triphenyltetrazolium chloride staining. Cardiac function was assessed by echocardiographic and haemodynamic analyses. The levels of creatine kinase-MB, lactate dehydrogenase, malondialdehyde, superoxide dismutase, interleukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-α) were detected using commercial kits. Apoptosis was measured by terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labelling staining and flow cytometry. The viability of H9c2 cells was determined by the Cell Counting Kit-8 assay. In vitro, the levels of IL-6 and TNF-α were measured by quantitative PCR. The expression levels of proteins associated with apoptosis, inflammation, and the Toll-like receptor 4/myeloid differentiation factor 88/nuclear factor kappa B (TLR4/MyD88/NF-κB) signalling pathway were detected by Western blot analysis. The RR, PR, QRS, and QTc intervals were assessed by surface ECG. The 90% action potential duration (APD90), threshold of APD alternans, and ventricular tachycardia inducibility were measured by the Langendorff perfusion technique. RESULTS: DAP preconditioning decreased myocardial I/R injury and hypoxia/reoxygenation (H/R) injury in cells. DAP preconditioning improved cardiac function after myocardial I/R injury. DAP preconditioning also suppressed apoptosis, attenuated oxidative stress, and inhibited inflammatory responses in vivo and in vitro. Furthermore, DAP preconditioning decreased the susceptibility to ventricular arrhythmia after myocardial I/R. Finally, DAP preconditioning inhibited the expression of TLR4, MyD88, and phosphorylated NF-κB (p-NF-κB)/P65 in mice subjected to I/R and cells subjected to H/R. CONCLUSIONS: DAP preconditioning protected against myocardial I/R injury and decreased susceptibility to ventricular arrhythmia by inhibiting the TLR4/MyD88/NF-κB signalling pathway.

Targeted ablation of cardiac sympathetic neurons improves ventricular electrical remodelling in a canine model of chronic myocardial infarction.

Aims: The purpose of this study was to evaluate the cardiac electrophysiologic effects of targeted ablation of cardiac sympathetic neurons (TACSN) in a canine model of chronic myocardial infarction (MI). Methods and results: Thirty-eight anaesthetized dogs were randomly assigned into the sham-operated, MI, and MI-TACSN groups, respectively. Myocardial infarction-targeted ablation of cardiac sympathetic neuron was induced by injecting cholera toxin B subunit-saporin compound in the left stellate ganglion (LSG). Five weeks after surgery, the cardiac function, heart rate variability (HRV), ventricular electrophysiological parameters, LSG function and neural activity, serum norepinephrine (NE), nerve growth factor (NGF), and brain natriuretic peptide (BNP) levels were measured. Cardiac sympathetic innervation was determined with immunofluorescence staining of growth associated protein-43 (GAP43) and tyrosine hydroxylase (TH). Compared with MI group, TACSN significantly improved HRV, attenuated LSG function and activity, prolonged corrected QT interval, decreased Tpeak-Tend interval, prolonged ventricular effective refractory period (ERP), and action potential duration (APD), decreased the slopes of APD restitution curves, suppressed the APD alternans, increased ventricular fibrillation threshold, and reduced serum NE, NGF, and BNP levels. Moreover, the densities of GAP43 and TH-positive nerve fibres in the infarcted border zone in the MI-TACSN group were lower than those in the MI group. Conclusion: Targeted ablation of cardiac sympathetic neuron attenuates sympathetic remodelling and improves ventricular electrical remodelling in the chronic phase of MI. These data suggest that TACSN may be a novel approach to treating ventricular arrhythmias.

Targeted ablation of cardiac sympathetic neurons attenuates adverse postinfarction remodelling and left ventricular dysfunction.

NEW FINDINGS: What is the central question of this study? Can targeted ablation of cardiac sympathetic neurons suppress myocardial infarction-induced adverse cardiac remodelling and left ventricular dysfunction? What is the main finding and its importance? Targeted ablation of cardiac sympathetic neurons significantly alleviated sympathetic remodelling and neuroendocrine activation, attenuated cardiac hypertrophy and fibrosis and improved left ventricular function. Thus, targeted ablation of cardiac sympathetic neurons might have a beneficial effect on adverse postinfarction remodelling and left ventricular dysfunction. ABSTRACT: Sympathetic overactivation is crucial in the development and progression of adverse cardiac remodelling and dysfunction. Targeted ablation of cardiac sympathetic neurons (TACSN) is an effective approach to inhibit overactivation of the sympathetic nervous system. The aim of this study was to investigate whether TACSN could suppress myocardial infarction (MI)-induced adverse cardiac remodelling and dysfunction, thereby producing protective effects. Thirty-eight dogs were randomly assigned into the sham-operated, MI or MI-TACSN group. The TACSN was induced by injecting cholera toxin B subunit-saporin compound into the stellate ganglia 1 week after MI. Five weeks after MI surgery, echocardiographic and haemodynamic parameters of cardiac function were significantly improved in the TACSN group compared with the MI group. In addition, TACSN attenuated the extent of cardiac hypertrophy and fibrosis and suppressed the increase in the plasma concentrations of noradrenaline, nerve growth factor, atrial natriuretic peptide, brain natriuretic peptide, angiotensin II and aldosterone. Furthermore, TACSN alleviated the growth associated protein-43-positive and tyrosine hydroxylase-positive nerve densities in the infarcted border zone and restored protein expression of the ß1 -adrenergic receptor in the left ventricular myocardium. These findings indicate that TACSN might have a beneficial effect on adverse postinfarction remodelling and left ventricular dysfunction, which might be attributable, at least in part, to the attenuation of both sympathetic remodelling and the cardiac neuroendocrine system.

Predictors of late atrial fibrillation recurrence after cryoballoon-based pulmonary vein isolation: a meta-analysis.

BACKGROUND: The recurrence rate of atrial fibrillation (AF) after cryoballoon ablation in drug refractory AF patients is high. Late-recurrence of AF has various predictors. AIM: The aim of the study was to explore the related risk factors that can effectively predict late AF recurrence after cryoballoon-based pulmonary vein isolation. METHODS: The PubMed and Web of Science databases were searched from 1 January 2013 to 1 August 2016, and studies were chosen that met the pre-stated inclusion criteria. The reference lists of the retrieved articles were also reviewed. Two authors independently extracted information on the designs of the studies. The strength of the relationship between different risk factors and late recurrence was assessed by the adjusted hazard ratio. RESULTS: A total of 16 papers met the inclusion criteria and were included in the meta-analysis. The hazard ratio of late atrial arrhythmia recurrence in patients with early recurrence was 4.19 compared with the reference group (95% CI 2.73-6.44, p < 0.00001); that of increased left atrial diameter was 1.25 (95% CI 1.12-1.3, p < 0.0001); that of a long duration of AF before ablation was 1.10 (95% CI 1.04-1.17, p < 0.0009); and that of persistent AF was 2.44 (95% CI 1.30-4.58, p < 0.006). However, there exists significant heterogeneity for each indicator, and a slight publication bias was observed. CONCLUSIONS: Our study suggests that early recurrence in the blanking period, increased left atrial size, a longduration of AF before ablation and persistent AF are independent predictors of late recurrence after cryoballoon ablation.

Regulator of G-protein signaling 5 protects cardiomyocytes against apoptosis during in vitro cardiac ischemia-reperfusion in mice by inhibiting both JNK1/2 and P38 signaling pathways.

Ischemic heart disease is one of the most common diseases in modern society. Ischemic myocardium can be salvaged by vascular recanalization therapy, but its benefit is attenuated by injury that can occur during reperfusion. And apoptotic cell death plays an important part in myocardial ischemia-reperfusion (IR) injury. Regulator of G-protein signaling 5 (RGS5), highly expressed in different cell types of the human adult heart, is a guanosine triphosphatase-activating protein to inhibit many signaling pathways such as c-Jun NH2-terminal kinase 1/2 (JNK1/2) and p38 which promote cardiac IR-induced apoptosis. However the role of RGS5 in cardiac IR-induced apoptosis remains unclear. An in vitro IR model was applied to the isolated hearts of wild type mice (WT), RGS5-transgenic mice (TG), and RGS5-knockout mice (KO). Our results revealed that compared with either WT or KO mice, TG mice showed inhibition of cardiomyocyte apoptosis as indicated by a greater increase of B cell lymphoma/lewkmia-2 (Bcl-2), and an obvious reduction in the positive expression of the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), Bcl-2 Associated X protein (Bax), and active caspase-3. Moreover, the inhibition of both JNK1/2 and p38 signaling markedly reversed IR-induced cardiomyocyte apoptosis in RGS5-KO mice. These studies show that RGS5 protects cardiomyocytes against apoptosis during IR through inhibiting both JNK1/2 and p38 signaling pathways.