Role of Early Left Atrial Functional Decline in Predicting Cardiotoxicity in HER2 Positive Breast Cancer Patients Treated With Trastuzumab.

Trastuzumab is widely used in HER2 breast cancer. However, it may cause left ventricular (LV) dysfunction. A decrease in LV global longitudinal strain (GLS) has been previously demonstrated to be a good predictor of subsequent cancer therapy related dysfunction (CTRCD). Left atrial morphological remodeling during Trastuzumab therapy has also been shown. The aim of this study is exploring the relationship between early changes in left atrial function and the development of Trastuzumab-induced cardiotoxicity. Consecutive patients with diagnosis of HER2+non-metastatic breast cancer treated with Trastuzumab were prospectively enrolled. A clinical, conventional, and advanced echocardiographic assessment was performed at baseline and every three months, until a one-year follow-up was reached. One-hundred-sixteen patients completed the 12 months follow-up, 10 (9%) cases of CTRCD were observed, all after the sixth month. GLS and LVEF significantly decreased in the CTRCD group at 6 months of follow-up, with an earlier (3 months) significant worsening in left atrial morpho-functional parameters. Systolic blood pressure, early peak atrial longitudinal strain (PALS), peak atrial contraction (PACS) and left atrial volume (LAVI) changes resulted independent predictors of CTRCD at multivariable logistic regression analysis. Moreover, early changes in PALS and PACS resulted good predictors of CTRCD development (AUC 0.85; p = 0.008, p < 0.001 and 0.77; p = 0.008, respectively). This prospective study emphasizes that the decline in PALS and PACS among trastuzumab-treated patients could possibly increase the accuracy in identifying future CTRCD in non-metastatic HER2 breast cancer cases, adding predictive value to conventional echocardiographic assessment.

Gender Differences in Cardiac Organ Damage in Arterial Hypertension: Assessing the Role of Drug Nonadherence.

INTRODUCTION: Cardiac organ damage like left ventricular (LV) hypertrophy and left atrial (LA) enlargement is more prevalent in women than men with hypertension, but the mechanisms underlying this gender difference remain unclear. METHODS: We tested the association of drug nonadherence with the presence of LV hypertrophy and LA enlargement by echocardiography in 186 women and 337 men with uncontrolled hypertension defined as daytime systolic blood pressure (BP) ≥ 135mmHg despite the prescription of at least two antihypertensive drugs. Drug adherence was assessed by measurements of serum drug concentrations interpreted by an experienced pharmacologist. Aldosterone-renin-ratio (ARR) was measured on actual medication. RESULTS: Women had a higher prevalence of LV hypertrophy (46% vs. 33%) and LA enlargement (79% vs 65%, both p < 0.05) than men, while drug nonadherence (8% vs. 9%, p > 0.514) did not differ. Women were older and had lower serum renin concentration and higher ARR than men, while 24-h systolic BP (141 ± 9 mmHg vs. 142 ± 9 mmHg), and the prevalences of obesity (43% vs. 50%) did not differ (all p > 0.10). In multivariable analyses, female gender was independently associated with a two-fold increased risk of LV hypertrophy (OR 2.01[95% CI 1.30-3.10], p = 0.002) and LA enlargement (OR 1.90 [95% CI 1.17-3.10], p = 0.010), while no association with drug nonadherence was found. Higher ARR was independently associated with LV hypertrophy in men only (OR 2.12 [95% CI 1.12-4.00] p = 0.02). CONCLUSIONS: Among patients with uncontrolled hypertension, the higher prevalence of LV hypertrophy and LA enlargement in women was not explained by differences in drug nonadherence. REGISTRATION: URL:  https://www. CLINICALTRIALS: gov ; Unique identifier: NCT03209154.

Administration of USP7 inhibitor p22077 alleviates Angiotensin II (Ang II)-induced atrial fibrillation in Mice.

Atrial fibrillation (AF), the most common cardiac arrhythmia, is an important contributor to mortality and morbidity. Ubquitin-specific protease 7 (USP7), one of the most abundant ubiquitin-specific proteases (USP), participated in many cellular events, such as cell proliferation, apoptosis, and tumourigenesis. However, its role in AF remains unknown. Here, the mice were treated with Ang II infusion to induce the AF model. Echocardiography was used to measure the atrial diameter. Electrical stimulation was programmed to measure the induction and duration of AF. The changes in atrial remodeling were measured using routine histologic analysis. Here, a significant increase in USP7 expression was observed in Ang II-stimulated atrial cardiomyocytes and atrial tissues, as well as in atrial tissues from patients with AF. The administration of p22077, the inhibitor of USP7, attenuated Ang II-induced inducibility and duration of AF, atrial dilatation, connexin dysfunction, atrial fibrosis, atrial inflammation, and atrial oxidase stress, and then inhibited the progression of AF. Mechanistically, the administration of p22077 alleviated Ang II-induced activation of TGF-ß/Smad2, NF-κB/NLRP3, NADPH oxidases (NOX2 and NOX4) signals, the up-regulation of CX43, ox-CaMKII, CaMKII, Kir2.1, and down-regulation of SERCA2a. Together, this study, for the first time, suggests that USP7 is a critical driver of AF and revealing USP7 may present a new target for atrial fibrillation therapeutic strategies.

Interleukin-33/ST2 axis involvement in atrial remodeling and arrhythmogenesis.

Interleukin (IL)-33, a cytokine involved in immune responses, can activate its receptor, suppression of tumorigenicity 2 (ST2), is elevated during atrial fibrillation (AF). However, the role of IL-33/ST2 signaling in atrial arrhythmia is unclear. This study explored the pathological effects of the IL-33/ST2 axis on atrial remodeling and arrhythmogenesis. Patch clamping, confocal microscopy, and Western blotting were used to analyze the electrical characteristics of and protein activity in atrial myocytes (HL-1) treated with recombinant IL-33 protein and/or ST2-neutralizing antibodies for 48 hrs. Telemetric electrocardiographic recordings, Masson's trichrome staining, and immunohistochemistry staining of the atrium were performed in mice receiving tail vein injections with nonspecific immunoglobulin (control), IL-33, and IL-33 combined with anti-ST2 antibody for 2 weeks. IL-33-treated HL-1 cells had a reduced action potential duration, lower L-type Ca2+ current, greater sarcoplasmic reticulum (SR) Ca2+ content, increased Na+/Ca2+ exchanger (NCX) current, elevation of K+ currents, and increased intracellular calcium transient. IL-33-treated HL-1 myocytes had greater activation of the calcium-calmodulin-dependent protein kinase II (CaMKII)/ryanodine receptor 2 (RyR2) axis and nuclear factor kappa B (NF-κB) / NLR family pyrin domain containing 3 (NLRP3) signaling than did control cells. IL-33 treated cells also had greater expression of Nav1.5, Kv1.5, NCX, and NLRP3 than did control cells. Pretreatment with neutralizing anti-ST2 antibody attenuated IL-33-mediated activation of CaMKII/RyR2 and NF-κB/NLRP3 signaling. IL-33-injected mice had more atrial ectopic beats and increased AF episodes, greater atrial fibrosis, and elevation of NF-κB/NLRP3 signaling than did controls or mice treated with IL-33 combined with anti-ST2 antibody. Thus, IL-33 recombinant protein treatment promotes atrial remodeling through ST2 signaling. Blocking the IL-33/ST2 axis might be an innovative therapeutic approach for patients with atrial arrhythmia and elevated serum IL-33.

Nicotinamide Riboside Alleviates Cardiac Dysfunction and Remodeling in Pressure Overload Cardiac Hypertrophy.

BACKGROUND: Cardiac hypertrophy is a compensatory response to pressure overload, which eventually leads to heart failure. The current study explored the protective effect of nicotinamide riboside (NR), a NAD+ booster that may be administered through the diet, on the occurrence of myocardial hypertrophy and revealed details of its underlying mechanism. METHODS: Transverse aortic constriction (TAC) surgery was performed to establish a murine model of myocardial hypertrophy. Mice were randomly divided into four groups: sham, TAC, sham+NR, and TAC+NR. NR treatment was given daily by oral gavage. Cardiac structure and function were assessed using small animal echocardiography. Mitochondrial oxidative stress was evaluated by dihydroethidium (DHE) staining, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity. Levels of expression of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), IL-1ß, TNF-α, and Sirtuin3 were measured by real-time PCR and ELISA. Expression levels of Caspase-1, Caspase-1 pro, cleaved Gasdermin D (GSDMD), NLRP3, ASC, Sirtuin3, ac-MnSOD, and total MnSOD were measured by Western blot. RESULTS: Reductions in the heart/body mass ratio (HW/BW) and lung/body mass ratio (LW/BW) and in ANP, BNP, and LDH levels were observed in the TAC group on the administration of NR (P < 0.05). Moreover, echocardiography data showed that cardiac dysfunction and structural changes caused by TAC were improved by NR treatment (P < 0.05). NR treatment also reduced levels of the inflammatory cytokines, IL-1ß and TNF-α, and attenuated activation of NLRP3 inflammasomes induced by TAC. Furthermore, changes in DHE staining, MDA content, and SOD activity indicated that NR treatment alleviated the oxidative stress caused by TAC. Data from ELISA and Western blots revealed elevated myocardial NAD+ content and Sirtuin3 activity and decreased acetylation of MnSOD after NR treatment, exposing aspects of the underlying signaling pathway. CONCLUSION: NR treatment alleviated TAC-induced pathological cardiac hypertrophy and dysfunction. Mechanically, these beneficial effects were attributed to the inhibition of NLRP3 inflammasome activation and myocardial inflammatory response by regulating the NAD+-Sirtuin3-MnSOD signaling pathway.

Targeting mitochondrial reactive oxygen species-mediated oxidative stress attenuates nicotine-induced cardiac remodeling and dysfunction.

Long-term nicotine intake is associated with an increased risk of myocardial damage and dysfunction. However, it remains unclear whether targeting mitochondrial reactive oxygen species (ROS) prevents nicotine-induced cardiac remodeling and dysfunction. This study investigated the effects of mitoTEMPO (a mitochondria-targeted antioxidant), and resveratrol (a sirtuin activator) , on nicotine-induced cardiac remodeling and dysfunction. Sprague-Dawley rats were administered 0.6 mg/kg nicotine daily with 0.7 mg/kg mitoTEMPO, 8 mg/kg resveratrol, or vehicle alone for 28 days. At the end of the study, rat hearts were collected to analyze the cardiac structure, mitochondrial ROS level, oxidative stress, and inflammation markers. A subset of rat hearts was perfused ex vivo to determine the cardiac function and myocardial susceptibility to ischemia-reperfusion injury. Nicotine administration significantly augmented mitochondrial ROS level, cardiomyocyte hypertrophy, fibrosis, and inflammation in rat hearts. Nicotine administration also induced left ventricular dysfunction, which was worsened by ischemia-reperfusion in isolated rat hearts. MitoTEMPO and resveratrol both significantly attenuated the adverse cardiac remodeling induced by nicotine, as well as the aggravation of postischemic ventricular dysfunction. Findings from this study show that targeting mitochondrial ROS with mitoTEMPO or resveratrol partially attenuates nicotine-induced cardiac remodeling and dysfunction.

Quercetin prevents isoprenaline-induced myocardial fibrosis by promoting autophagy via regulating miR-223-3p/FOXO3.

Atrial fibrillation (AF) is the common arrhythmias. Myocardial fibrosis (MF) is closely related to atrial remodeling and leads to AF. MF is the main cause of cardiovascular diseases and a pathological basis of AF. Thus, the underlying mechanism in MF and AF development should be fully elucidated for AF therapeutic innovation. Autophagy is a highly conserved lysosomal degradation pathway, and the relationship between autophagy and MF has been previously shown. Moreover, research reported that quercetin (Que) could ameliorate MF. The current study aimed to explore the mechanism of Que in MF. The results in this study showed that in clinical AF patients and in aged rats, miR-223-3p was high-expressed, while FOXO3 and autophagy pathway related proteins, such as ATG7, p62/SQSTM1 and the ratio of LC3B-II/LC3B-I were significantly inhibited. In vivo and in vitro studies, we found that Que can effectively inhibit the expression of miR-223-3p in AF model cells and rats myocardial tissues, and meanwhile enhance the expression of FOXO3 and activate the autophagy pathway, and significantly inhibit myocardial fibrosis, and improve myocardial remodeling in atrial fibrillation. All in all, in this study, we found that Que prevents isoprenaline-induced MF by increasing autophagy via regulating miR-223-3p/FOXO3.

Piezo1 and BKCa channels in human atrial fibroblasts: Interplay and remodelling in atrial fibrillation.

AIMS: Atrial Fibrillation (AF) is an arrhythmia of increasing prevalence in the aging populations of developed countries. One of the important indicators of AF is sustained atrial dilatation, highlighting the importance of mechanical overload in the pathophysiology of AF. The mechanisms by which atrial cells, including fibroblasts, sense and react to changing mechanical forces, are not fully elucidated. Here, we characterise stretch-activated ion channels (SAC) in human atrial fibroblasts and changes in SAC- presence and activity associated with AF. METHODS AND RESULTS: Using primary cultures of human atrial fibroblasts, isolated from patients in sinus rhythm or sustained AF, we combine electrophysiological, molecular and pharmacological tools to identify SAC. Two electrophysiological SAC- signatures were detected, indicative of cation-nonselective and potassium-selective channels. Using siRNA-mediated knockdown, we identified the cation-nonselective SAC as Piezo1. Biophysical properties of the potassium-selective channel, its sensitivity to calcium, paxilline or iberiotoxin (blockers), and NS11021 (activator), indicated presence of calcium-dependent 'big potassium channels' (BKCa). In cells from AF patients, Piezo1 activity and mRNA expression levels were higher than in cells from sinus rhythm patients, while BKCa activity (but not expression) was downregulated. Both Piezo1-knockdown and removal of extracellular calcium from the patch pipette resulted in a significant reduction of BKCa current during stretch. No co-immunoprecipitation of Piezo1 and BKCa was detected. CONCLUSIONS: Human atrial fibroblasts contain at least two types of ion channels that are activated during stretch: Piezo1 and BKCa. While Piezo1 is directly stretch-activated, the increase in BKCa activity during mechanical stimulation appears to be mainly secondary to calcium influx via SAC such as Piezo1. During sustained AF, Piezo1 is increased, while BKCa activity is reduced, highlighting differential regulation of both channels. Our data support the presence and interplay of Piezo1 and BKCa in human atrial fibroblasts in the absence of physical links between the two channel proteins.

Treatment-Related Changes in Left Atrial Structure in Atrial Fibrillation: Findings From the CABANA Imaging Substudy.

[Figure: see text].

NGF nanoparticles enhance the potency of transplanted human umbilical cord mesenchymal stem cells for myocardial repair.

In this study, we investigated whether human umbilical cord mesenchymal stem cell (hUCMSC) fibrin patches loaded with nerve growth factor (NGF) poly(lactic-co-glycolic acid) (PLGA) nanoparticles could enhance the therapeutic potency of hUCMSCs for myocardial infarction (MI). In vitro, NGF significantly improved the proliferation of hUCMSCs and mitigated cytotoxicity and apoptosis under hypoxic injury. NGF also promoted the paracrine effects of hUCMSCs on angiogenesis and cardiomyocyte protection. The tyrosine kinase A (TrkA) and phosphoinositide 3-kinase (PI3K)-serine/threonine protein kinase (Akt) signaling pathways in hUCMSCs were involved in the NGF-induced protection. NGF PLGA nanoparticles continued to release NGF for at least 1 mo and also exerted a protective effect on hUCMSCs, the same with free NGF. In vivo, we treated MI mice with nothing (MI group), a cell-free fibrin patch with blank PLGA nanoparticles (MI + OP group), a cell-free fibrin patch with NGF nanoparticles (MI + NGF group), and hUCMSC fibrin patches with blank PLGA nanoparticles (MI + MSC group) or NGF PLGA nanoparticles (MSC + NGF group). Among these groups, the MSC + NGF group exhibited the best cardiac contractile function, the smallest infarct size, and the thickest ventricular wall. The application of NGF PLGA nanoparticles significantly improved the retention of transplanted hUCMSCs and enhanced their ability to reduce myocardial apoptosis and promote angiogenesis in the mouse heart after MI. These findings demonstrate the promising therapeutic potential of hUCMSC fibrin cardiac patches loaded with NGF PLGA nanoparticles.NEW & NOTEWORTHY NGF PLGA nanoparticles can exert a protective effect on hUCMSCs and promote the paracrine effects of hUCMSCs on angiogenesis and cardiomyocyte protection through TrkA-PI3K/Akt signaling pathway, the same with free NGF. The application of NGF PLGA nanoparticles in the hUCMSC fibrin cardiac patches can significantly improve the retention of transplanted hUCMSCs and enhance their ability to reduce myocardial apoptosis and promote angiogenesis in the mouse heart after MI.

Effects of the L/N-Type Ca2+ Channel Blocker Cilnidipine on the Cardiac Histological Remodelling and Inducibility of Atrial Fibrillation in High-Salt-Fed Rats.

High salt intake has been shown to induce hypertrophy and fibrosis in the atria and ventricles, which could result in the development of atrial fibrillation (AF). Whereas the development of AF is suggested to be prevented by renin-angiotensin system (RAS) inhibitors, recent findings have indicated that this prevention is closely associated with their antihypertensive effects. In this study, we investigated whether the L/N-type Ca2+ channel blocker cilnidipine counteracts salt-induced atrial and ventricular remodelling and the inducibility of AF. Cilnidipine was orally administered to Dahl salt-sensitive rats fed with an 8% NaCl diet at 10 mg/kg for 5 weeks, and then electrophysiological evaluation and histological analyses were performed. The effects were compared with those of the L-type Ca2+ channel blocker amlodipine at 3 mg/kg. Following the intake of the 8% NaCl diet, the blood pressure (BP) increased, and fibrosis was induced in the atria and ventricles. Cilnidipine decreased BP, and the extent of the decrease in the cilnidipine group was similar to those in the amlodipine group. Cilnidipine produced a greater decrease in the fibrotic area in the atria and ventricles than amlodipine. The cilnidipine group shortened the AF duration from 7.43 ± 3.16 to 2.95 ± 1.73 s, which had been increased by NaCl intake. Plasma noradrenaline levels in the cilnidipine group were lower than those in the amlodipine group. Thus, the suppressive effects of cilnidipine on the salt-induced atrial and ventricular remodelling, fibrosis, and AF sustainability might be closely associated with its N-type Ca2+ channel-blocking actions.

Activation of NADPH oxidase mediates mitochondrial oxidative stress and atrial remodeling in diabetic rabbits.

AIMS: The mechanisms of atrial fibrillation (AF) in diabetes mellitus (DM) involve a complex interplay between increased oxidative stress, mitochondrial dysfunction and atrial remodeling. In this study, we examined the effects of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation on mitochondrial oxidative stress and atrial remodeling in a rabbit model of diabetes mellitus (DM). MAIN METHODS: Healthy rabbits were selected and randomly divided into control, diabetic and apocynin administration group. Parameters of echocardiography, atrial electrophysiology, oxidative stress and mitochondrial function were compared between the different groups. KEY FINDINGS: Compared to the control group, the DM group showed higher activity of NADPH oxidase, increased oxidative stress, larger left atrial diameter, a reduction in atrial mean conduction velocity. These findings were associated with increased interstitial fibrosis of the atria and higher atrial fibrillation (AF) inducibility. Moreover, atrial ultrastructure and mitochondrial function such as the mitochondrial respiratory control rate (RCR) were impaired. NADPH oxidase inhibition using the pharmacological agent apocynin improved these changes. SIGNIFICANCE: NADPH oxidase activity plays an important role in mitochondrial oxidative stress, which is associated with AF inducibility by promoting adverse atrial remodeling. The NADPH oxidase inhibitor apocynin can prevent these pathological changes and may be a potential drug for AF treatment.

Canagliflozin Suppresses Atrial Remodeling in a Canine Atrial Fibrillation Model.

Background Recent clinical trials have demonstrated the possible pleiotropic effects of SGLT2 (sodium-glucose cotransporter 2) inhibitors in clinical cardiovascular diseases. Atrial electrical and structural remodeling is important as an atrial fibrillation (AF) substrate. Methods and Results The present study assessed the effect of canagliflozin (CAN), an SGLT2 inhibitor, on atrial remodeling in a canine AF model. The study included 12 beagle dogs, with 10 receiving continuous rapid atrial pacing and 2 acting as the nonpacing group. The 10 dogs that received continuous rapid atrial pacing for 3 weeks were subdivided as follows: pacing control group (n=5) and pacing+CAN (3 mg/kg per day) group (n=5). The atrial effective refractory period, conduction velocity, and AF inducibility were evaluated weekly through atrial epicardial wires. After the protocol, atrial tissues were sampled for histological examination. The degree of reactive oxygen species expression was evaluated by dihydroethidium staining. The atrial effective refractory period reduction was smaller (P=0.06) and the degree of conduction velocity decrease was smaller in the pacing+CAN group compared with the pacing control group (P=0.009). The AF inducibility gradually increased in the pacing control group, but such an increase was suppressed in the pacing+CAN group (P=0.011). The pacing control group exhibited interstitial fibrosis and enhanced oxidative stress, which were suppressed in the pacing+CAN group. Conclusions CAN and possibly other SGLT2 inhibitors might be useful for preventing AF and suppressing the promotion of atrial remodeling as an AF substrate.

Effect of sodium-glucose cotransporter 2 inhibitors on cardiac structure and function in type 2 diabetes mellitus patients with or without chronic heart failure: a meta-analysis.

BACKGROUND: Although the benefits of sodium-glucose cotransporter 2 inhibitors (SGLT2i) on cardiovascular events have been reported in patients with type 2 diabetes mellitus (T2DM) with or without heart failure (HF), the impact of SGLT2i on cardiac remodelling remains to be established. METHODS: We searched the PubMed, Embase, Cochrane Library and Web of Science databases up to November 16th, 2020, for randomized controlled trials reporting the effects of SGLT2i on parameters of cardiac structure, cardiac function, plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) level or the Kansas City Cardiomyopathy Questionnaire (KCCQ) score in T2DM patients with or without chronic HF. The effect size was expressed as the mean difference (MD) or standardized mean difference (SMD) and its 95% confidence interval (CI). Subgroup analyses were performed based on the stage A-B or stage C HF population and HF types. RESULTS: Compared to placebo or other antidiabetic drugs, SGLT2i showed no significant effects on left ventricular mass index, left ventricular end diastolic volume index, left ventricular end systolic volume index, or left atrial volume index. SGLT2i improved left ventricular ejection fraction only in the subgroup of HF patients with reduced ejection fraction (MD 3.16%, 95% CI 0.11 to 6.22, p = 0.04; I2 = 0%), and did not affect the global longitudinal strain in the overall analysis including stage A-B HF patients. SGLT2i showed benefits in the E/e' ratio (MD - 0.45, 95% CI - 0.88 to - 0.03, p = 0.04; I2 = 0%), plasma NT-proBNP level (SMD - 0.09, 95% CI - 0.16 to - 0.03, p = 0.004; I2 = 0%), and the KCCQ score (SMD 3.12, 95% CI 0.76 to 5.47, p  = 0.01; I2 = 0%) in the overall population. CONCLUSION: The use of SGLT2i was associated with significant improvements in cardiac diastolic function, plasma NT-proBNP level, and the KCCQ score in T2DM patients with or without chronic HF, but did not significantly affect cardiac structural parameters indexed by body surface area. The LVEF level was improved only in HF patients with reduced ejection fraction.

Dual SGLT-1 and SGLT-2 inhibition improves left atrial dysfunction in HFpEF.

BACKGROUND: Sodium-glucose linked transporter type 2 (SGLT-2) inhibition has been shown to reduce cardiovascular mortality in heart failure independently of glycemic control and prevents the onset of atrial arrhythmias, a common co-morbidity in heart failure with preserved ejection fraction (HFpEF). The mechanism behind these effects is not fully understood, and it remains unclear if they could be further enhanced by additional SGLT-1 inhibition. We investigated the effects of chronic treatment with the dual SGLT-1&2 inhibitor sotagliflozin on left atrial (LA) remodeling and cellular arrhythmogenesis (i.e. atrial cardiomyopathy) in a metabolic syndrome-related rat model of HFpEF. METHODS: 17 week-old ZSF-1 obese rats, a metabolic syndrome-related model of HFpEF, and wild type rats (Wistar Kyoto), were fed 30 mg/kg/d sotagliflozin for 6 weeks. At 23 weeks, LA were imaged in-vivo by echocardiography. In-vitro, Ca2+ transients (CaT; electrically stimulated, caffeine-induced) and spontaneous Ca2+ release were recorded by ratiometric microscopy using Ca2+-sensitive fluorescent dyes (Fura-2) during various experimental protocols. Mitochondrial structure (dye: Mitotracker), Ca2+ buffer capacity (dye: Rhod-2), mitochondrial depolarization (dye: TMRE) and production of reactive oxygen species (dye: H2DCF) were visualized by confocal microscopy. Statistical analysis was performed with 2-way analysis of variance followed by post-hoc Bonferroni and student's t-test, as applicable. RESULTS: Sotagliflozin ameliorated LA enlargement in HFpEF in-vivo. In-vitro, LA cardiomyocytes in HFpEF showed an increased incidence and amplitude of arrhythmic spontaneous Ca2+ release events (SCaEs). Sotagliflozin significantly reduced the magnitude of SCaEs, while their frequency was unaffected. Sotagliflozin lowered diastolic [Ca2+] of CaT at baseline and in response to glucose influx, possibly related to a ~ 50% increase of sodium sodium-calcium exchanger (NCX) forward-mode activity. Sotagliflozin prevented mitochondrial swelling and enhanced mitochondrial Ca2+ buffer capacity in HFpEF. Sotagliflozin improved mitochondrial fission and reactive oxygen species (ROS) production during glucose starvation and averted Ca2+ accumulation upon glycolytic inhibition. CONCLUSION: The SGLT-1&2 inhibitor sotagliflozin ameliorated LA remodeling in metabolic HFpEF. It also improved distinct features of Ca2+-mediated cellular arrhythmogenesis in-vitro (i.e. magnitude of SCaEs, mitochondrial Ca2+ buffer capacity, diastolic Ca2+ accumulation, NCX activity). The safety and efficacy of combined SGLT-1&2 inhibition for the treatment and/or prevention of atrial cardiomyopathy associated arrhythmias should be further evaluated in clinical trials.

Activation of AMP-Activated Protein Kinases Prevents Atrial Fibrillation.

Atrial fibrillation (AF) is common, yet there is no preventive therapy for AF. We tested the efficacy of AMP-activated protein kinase (AMPK) activators, metformin, and aspirin, in primary prevention of AF in cardiac-specific liver kinase B1 (LKB1) knockout (KO) mouse model of AF. Incidence of spontaneous AF was significantly reduced in treated KO mice with metformin (10 mg/kg/day) (8.3% in male and 10.3% in female) and aspirin (20 mg/kg/day) (29.4% in male and 21.4% in female) compared with untreated littermates (81% in male and 67% in female) at 8 weeks (p < 0.05). Prevention of AF was associated with activation of AMPK in treated mice and thereby improvement of mitochondrial function, gap junction proteins (connexin 40/43), and intra- and inter-cellular ultrastructure in atrial myocardium. Fibrosis was significantly less in treated mice atria. Pharmacological activation of AMPK is an effective upstream therapy for the primary prevention of AF in susceptible heart. Graphical abstract.

The inflammation-resolution promoting molecule resolvin-D1 prevents atrial proarrhythmic remodelling in experimental right heart disease.

AIMS: Inflammation plays a role in atrial fibrillation (AF), but classical anti-inflammatory molecules are ineffective. Recent evidence suggests that failure of inflammation-resolution causes persistent inflammatory signalling and that a novel drug-family called resolvins promotes inflammation-resolution. Right heart disease (RHD) is associated with AF; experimental RHD shows signs of atrial inflammatory-pathway activation. Here, we evaluated resolvin-therapy effects on atrial arrhythmogenic remodelling in experimental RHD. METHODS AND RESULTS: Pulmonary hypertension and RHD were induced in rats with an intraperitoneal injection of 60 mg/kg monocrotaline (MCT). An intervention group received daily resolvin-D1 (RvD1), starting 1 day before MCT administration. Right atrial (RA) conduction and gene-expression were analysed respectively by optical mapping and qPCR/gene-microarray. RvD1 had no or minimal effects on MCT-induced pulmonary artery or right ventricular remodelling. Nevertheless, in vivo transoesophageal pacing induced atrial tachyarrhythmias in no CTRL rats vs. 100% MCT-only rats, and only 33% RvD1-treated MCT rats (P < 0.001 vs. MCT-only). Conduction velocity was significantly decreased by MCT, an effect prevented by RvD1. RHD caused RA dilation and fibrosis. RvD1 strongly attenuated RA fibrosis but had no effect on RA dilation. MCT increased RA expression of inflammation- and fibrosis-related gene-expression pathways on gene-microarray transcriptomic analysis, effects significantly attenuated by RvD1 (334 pathways enriched in MCT-rats vs. control; only 177 dysregulated by MCT with RvD1 treatment). MCT significantly increased RA content of type 1 (proinflammatory) CD68-positive M1 macrophages without affecting type 2 (anti-inflammatory) M2 macrophages. RvD1-treated MCT-rat RA showed significant reductions in proinflammatory M1 macrophages and increases in anti-inflammatory M2 macrophages vs. MCT-only. MCT caused statistically significant increases in protein-expression (western blot) of COL3A1, ASC, CASP1, CASP8, IL1ß, TGFß3, CXCL1, and CXCL2, and decreases in MMP2, vs. control. RvD1-treatment suppressed all these MCT-induced protein-expression changes. CONCLUSION: The inflammation-resolution enhancing molecule RvD1 prevents AF-promoting RA remodelling, while suppressing inflammatory changes and fibrotic/electrical remodelling, in RHD. Resolvins show potential promise in combating atrial arrhythmogenic remodelling by suppressing ongoing inflammatory signalling.

Increased Susceptibility of Atrial Fibrillation Induced by Hyperuricemia in Rats: Mechanisms and Implications.

High levels of serum uric acid is closely associated with atrial fibrillation (AF); nonetheless, the detailed mechanisms remain unknown. Therefore, this work examined the intricate mechanisms of AF triggered by hyperuricemia and the impact of the uricosuric agent benzbromarone on atrial remodeling in hyperuricemic rats. After adjusting baseline serum uric acid levels, a total of 28 healthy male adult Sprague Dawley rats were randomly divided into 4 groups, namely, control (CTR), hyperuricemia (oxonic acid potassium salt, OXO) and benzbromarone (+ BBR), and OXO withdrawal groups. Primary rat cardiomyocytes were cultured with uric acid for 24 h to investigate the direct influence of uric acid on cardiomyocytes. Results revealed that AF vulnerability and AF duration were dramatically greater in hyperuricemic rats (OXO group), while the atrial effective refractory periods (AERPs) were significantly shorter. Meanwhile, BBR treatment and withdrawal of 2% OXO administration remarkably reduced AF inducibility and shortened AF duration. Moreover, abnormal morphology of atrial myocytes, atrial fibrosis, apoptosis, and substantial sympathetic nerve sprouting were observed in hyperuricemic rats. Apoptosis and fibrosis of atria were partly mediated by caspase-3, BAX, TGF-ß1, and α-smooth muscle actin. Uric acid significantly induced primary rat cardiomyocyte apoptosis and fibrosis in vitro. Also, we found that sympathetic nerve sprouting was markedly upregulated in the atria of hyperuricemia rats, and was restored by BRB or absence of OXO administration. In summary, our study confirmed that AF induced by hyperuricemic rats occurred primarily via induction of atrial remodeling, thereby providing a novel potential treatment approach for hyperuricemia-related AF.

Attenuation of atrial remodeling by aliskiren via affecting oxidative stress, inflammation and PI3K/Akt signaling pathway.

INTRODUCTION: Atrial fibrillation (AF) is the most common type of arrhythmia. Atrial remodeling is a major factor to the AF substrate. The purpose of the study is to explore whether aliskiren (ALS) has a cardioprotective effect and its potential molecular mechanisms on atrial remodeling. METHODS: In acute experiments, dogs were randomly assigned to Sham, Paced and Paced+aliskiren (10 mg kg-1) (Paced+ALS) groups, with 7 dogs in each group. Rapid atrial pacing (RAP) was maintained at 600 bpm for 2 h for paced and Paced+ALS groups and atrial effective refractory periods (AERPs), inducibility of AF (AFi) and average duration time (ADT) were measured. In chronic experiments, there were 5 groups: Sham, Sham+ALS, Paced, Paced+ALS and Paced+ALS+PI3K antagonist wortmannin (WM) (70 µg kg-1 day-1). RAP at 500 beats/min was maintained for 2 weeks. Inflammation and oxidative stress indicators were measured by ELISA assay, echocardiogram and pathology were used to assess atrial structural remodeling, phosphatidylinositol 3-hydroxy kinase/protein kinase B (PI3K/Akt) signaling pathways were studied by RT-PCR and western blotting to evaluate whether the cardioprotective effect of ALS works through PI3K/Akt signaling pathway. RESULTS: The electrophysiological changes were observed after 2-h pacing. The AERP shortened with increased AFi and ADT, which was attenuated by ALS (P < 0.05). After pacing for 2 weeks, oxidative stress and inflammation markers in the Paced group were significantly higher than those in the Sham group (P < 0.01) and were reduced by ALS treatment (P < 0.01). The reduced level of antioxidant enzymes caused by RAP was also found to be elevated in ALS-treated group (P < 0.01). The results of pathology and echocardiography showed that RAP can cause atrial enlargement, fibrosis (P < 0.01), and were attenuated in ALS treatment group. The PI3K/Akt signaling pathway were downregulated induced by RAP. ALS could upregulate the PI3K/Akt pathway expression (P < 0.05). Furthermore, the cardioprotective effects in structural remodeling of ALS were suppressed by WM. CONCLUSIONS: ALS may offer cardioprotection in RAP-induced atrial remodeling, which may partly be ascribed to its anti-inflammatory and anti-oxidative stress action and the regulation of PI3K/Akt signaling pathway.

Untargeted metabolomics and lipidomics uncovering the cardioprotective effects of Huanglian Jiedu Decoction on pathological cardiac hypertrophy and remodeling.

ETHNOPHARMACOLOGICAL RELEVANCE: As a classic herbal prescription, Huanglian Jiedu Decoction (HLJDD) exhibits positive effects against cardiac dysfunction. However, its cardioprotective effects and potential mechanism(s) of action still need to be systematically investigated. AIM OF THE STUDY: This study aimed to reveal the underlying therapeutic mechanism of HLJDD on transverse aortic constriction (TAC)-induced pathological cardiac hypertrophy and remodeling. MATERIALS AND METHODS: TAC-induced cardiac hypertrophy and remodeling mice model was established to evaluate the therapeutic effects of HLJDD. Serum untargeted metabolomics and lipidomic profiling were performed using ultra-performance liquid chromatography quadrupole-time-of-flight mass spectrometry coupled with multivariate statistical analyses. RESULTS: Oral administration of HLJDD (2.5 g/kg/day, 5.0 g/kg/day) significantly improved the heart morphology, enhanced the heart function, and alleviated the accumulation of fibrosis in the interstitial space and the infiltration of inflammatory cells in TAC-stimulated mice. Serum untargeted metabolomics analysis showed that significant alterations were observed in metabolic signatures between the TAC-model and sham group. Principal component analysis and orthogonal partial least-squares discriminant analysis screened 59 differential metabolic features and 13 metabolites were identified. The disturbed metabolic pathways in TAC group mainly related to lipid metabolism. Further serum lipidomic profiling showed that most lipids including cholesterol esters, ceramides, glycerides, fatty acids and phospholipids were decreased in TAC group and these alterations were reversed after HLJDD intervention. CONCLUSION: HLJDD alleviates TAC-induced pathological cardiac hypertrophy and remodeling, and its potential therapeutic mechanism involves the regulation of lipid metabolism.