Impact of heart rate changes during hospitalization on outcome in heart failure with preserved ejection fraction.

AIMS: The benefits of lowering heart rate (HR) in heart failure (HF) with preserved ejection fraction (HFpEF) patients are still a matter of debate. This study aimed to investigate the relationship between changes in HR during hospitalization and cardiovascular (CV) events and all-cause death in hospitalized HFpEF patients. METHODS AND RESULTS: Hospitalized HF patients between January 2017 and December 2021 were consecutively enrolled in a national, multicentred, and prospective registry database, the China Cardiovascular Association Database-HF Center Registry. HF patients with a left ventricular ejection fraction of ≥50% were defined as HFpEF patients. The study analysed admission/discharge HR, change in HR during hospitalization (∆HR), and ∆HR ratio (∆HR/admission HR). The patients were categorized into three groups: no HR dropping group (ΔHR ratio > 0.0%), moderate HR dropping group (-15% < ΔHR ratio ≤ 0.0%), and excessive HR dropping group (ΔHR ratio ≤ -15%). All patients were followed up for 12 months. The primary endpoint was CV events (CV death or HF rehospitalization). The secondary endpoint was all-cause death. A total of 19 510 HFpEF patients (9750 males, mean age 71.9 ± 12.2 years) were included, with 4575 in the no HR dropping group, 8434 in the moderate HR dropping group, and 6501 in the excessive HR dropping group. Excessive HR dropping during hospitalization was significantly associated with an increased risk of CV events (17.1%) compared with the no HR dropping group (14.5%, P < 0.001) or the moderate HR dropping group (14.0%, P < 0.001), although all-cause mortality was similar among the three groups. After adjusting for multiple confounding factors, excessive HR dropping remained an independent predictor of increased CV event risk [hazard ratio 1.197, 95% confidence interval (CI) 1.078-1.328]. Subgroup analysis revealed that the prognostic impact of excessive HR dropping on increased CV event risk remained in the subgroups of older age, New York Heart Association class IV, ischaemic HF, higher left ventricular ejection fraction, absence of chronic kidney disease, and use of beta-blockers or ivabradine. Independent determinants associated with excessive HR dropping during admission included use of beta-blockers [odds ratio (OR) 1.683, 95% CI 1.558-1.819], lower discharge diastolic blood pressure (OR 0.988, 95% CI 0.985-0.991), no pacemaker (OR 0.501, 95% CI 0.416-0.603), coexisting atrial fibrillation or atrial flutter (OR 1.327, 95% CI 1.218-1.445), and use of digoxin (OR 1.340, 95% CI 1.213-1.480). CONCLUSIONS: In hospitalized HFpEF patients, excessive HR dropping during hospitalization is associated with an increased risk of CV death or HF rehospitalization. These findings highlight the importance of HR monitoring and avoiding excessively slowing down HR in hospitalized HFpEF patients to reduce the risk of CV events.

Accumulation of endogenous adenosine improves cardiomyocyte metabolism via epigenetic reprogramming in an ischemia-reperfusion model.

Adenosine kinase (ADK) plays the major role in cardiac adenosine metabolism, so that inhibition of ADK increases myocardial adenosine levels. While the cardioprotective actions of extracellular adenosine against ischemia/reperfusion (I/R) are well-established, the role of cellular adenosine in protection against I/R remains unknown. Here we investigated the role of cellular adenosine in epigenetic regulation on cardiomyocyte gene expression, glucose metabolism and tolerance to I/R. Evans blue/TTC staining and echocardiography were used to assess the extent of I/R injury in mice. Glucose metabolism was evaluated by positron emission tomography and computed tomography (PET/CT). Methylated DNA immunoprecipitation (MeDIP) and bisulfite sequencing PCR (BSP) were used to evaluate DNA methylation. Lentiviral/adenovirus transduction was used to overexpress DNMT1, and the OSI-906 was administered to inhibit IGF-1. Cardiomyocyte-specific ADK/IGF-1-knockout mice were used for mechanistic experiments.Cardiomyocyte-specific ADK knockout enhanced glucose metabolism and ameliorated myocardial I/R injury in vivo. Mechanistically, ADK deletion caused cellular adenosine accumulation, decreased DNA methyltransferase 1 (DNMT1) expression and caused hypomethylation of multiple metabolic genes, including insulin growth factor 1 (IGF-1). DNMT1 overexpression abrogated these beneficial effects by enhancing apoptosis and decreasing IGF-1 expression. Inhibition of IGF-1 signaling with OSI-906 or genetic knocking down of IGF-1 also abrogated the cardioprotective effects of ADK knockout, revealing the therapeutic potential of increasing IGF-1 expression in attenuating myocardial I/R injury. In conclusion, the present study demonstrated that cardiomyocyte ADK deletion ameliorates myocardial I/R injury via epigenetic upregulation of IGF-1 expression via the cardiomyocyte adenosine/DNMT1/IGF-1 axis.

Mitochondrial aldehyde dehydrogenase rescues against diabetic cardiomyopathy through GSK3ß-mediated preservation of Mitochondrial integrity and parkin-mediated mitophagy.

Mitochondrial aldehyde dehydrogenase (ALDH2) offers proven cardiovascular benefit although its impact in diabetes remains elusive. This study examined the effect of ALDH2 overexpression (OE) and knockout (KO) on diabetic cardiomyopathy and mechanism involved with a focus on mitochondrial integrity. ALDH2 OE and KO mice were challenged with streptozotocin (STZ, 200 mg/kg. i.p.) to establish diabetes. Diabetic patients displayed reduced plasma ALDH2 activity, cardiac remodeling and diastolic dysfunction. STZ challenge prompted reduced respiratory exchange ratio (RER), dampened fractional shortening, ejection fraction, increased LV end systolic and diastolic diameters, cardiac remodeling, cardiomyocyte contractile and intracellular Ca2+ defects (depressed peak shortening and maximal velocity of shortening/relengthening, prolonged relengthening, dampened intracellular Ca2+ rise and clearance), myocardial ultrastructural injury, oxidative stress, apoptosis and mitochondrial damage, the effects of which were overtly attenuated and accentuated by ALDH2 OE and KO, respectively. Immunoblotting revealed downregulated mitochondrial proteins PPARγ coactivator 1α (PGC-1α) and UCP-2, Ca2+ regulatory proteins including SERCA and Na+-Ca2+ exchanger, elevated phospholamban, dampened autophagy and mitophagy (LC3B ratio, TOM20, Parkin, FUNDC1 and BNIP3), disrupted phosphorylation of Akt, GSK3ß and Foxo3a, and elevated PTEN phosphorylation, the effect of which was reversed and worsened by ALDH2 OE and KO, respectively (except FUNDC1 and BNIP3). In vivo and in vitro data revealed that novel ALDH2 activator torezolid/Alda-1 protected against STZ or high glucose-induced cardiac anomalies, the effect was nullified by inhibition of Akt, GSK3ß, Parkin and mitochondrial coupling. Our data discerned a vital role for ALDH2 in diabetic cardiomyopathy possibly through regulation of Akt, GSK3ß activation, parkin mitophagy and mitochondrial function.

VEGFR endocytosis regulates the angiogenesis in a mouse model of hindlimb ischemia.

BACKGROUND: The regulation of angiogenesis in the treatment of cardiovascular diseases has been widely studied and the vascular endothelial growth factor (VEGF) families and VEGF receptor (VEGFR) have been proven to be one of the key regulators. The VEGFR endocytosis has been recently proved to be involved in the regulation of angiogenesis. Our previous study showed that the upregulation of VEGFR endocytosis enhanced angiogenesis in vitro. In this research, we utilized mice with induced hindlimb ischemia, as a model to investigate the role of VEGFR endocytosis in the regulation of angiogenesis in vivo. Our goal was to observe the effect of revascularization with different degrees of VEGFR endocytosis after injecting atypical protein kinase C inhibitor (αPKCi) and dynasore, which could respectively promote and inhibit the VEGFR endocytosis. METHODS: We induced the hindlimb ischemia in adult male mice by ligating the hindlimb artery. By directly injecting the ischemic muscles with endothelial progenitor cells (EPCs) alone or EPCs + αPKCi/EPCs + dynasore or control medium (sham group), we divided the mice into four groups and detected lower limb blood flow using a laser Doppler blood perfusion imager. We also measured the immunohistochemistry (IHC) of markers for angiogenesis, such as CD31 and alpha smooth muscle actin (α-SMA) in the ischemic hindlimb tissues. RESULTS: We demonstrated VEGFR endocytosis played an important role in the angiogenesis of the ischemic hindlimb model in vivo. By using atypical PKC inhibitor that increase the VEGFR endocytosis, the angiogenesis in the mice model was promoted. Treatment with EPCs + αPKCi showed greater effects on blood perfusion recovery and increased the α-SMA-positive vessels. CONCLUSIONS: The regulation of VEGFR endocytosis represents a valuable method of improving angiogenesis and thus revascularization in ischemic disease model.

Novel idiopathic DCM-related SCN5A variants localised in DI-S4 predispose electrical disorders by reducing peak sodium current density.

BACKGROUND: Variants of SCN5A, encoding cardiac sodium channel, have been linked to the development of dilated cardiomyopathy (DCM). We aimed to explore novel SCN5A variants in patients with idiopathic DCM (iDCM) and to identify the distribute characteristics and pathological mechanisms as well as clinical phenotypes associated with the variants in patients with iDCM. METHODS: SCN5A exons sequencing was performed inpatients with iDCM (n=90) and two control cohorts (arrhythmias group, n=90, and healthy group, n=195). Clinical characteristics were compared between carriers and non-carriers. We then generated a novel heterozygous knock-in (KI) mouse by homologous recombination. Cardiac function, electrical parameters and histological characteristics were examined at basal or stimulating condition. RESULTS: We found three novel non-synonymous SCN5A variants associated with iDCM, including c.674G>A, c.677C>T, and c.4340T>A. The newly defined iDCM-related variants mainly located in the S4 segment of domain I (DI-S4). Incidence of atrioventricular block was significantly higher in mutant patients with iDCM than in non-carriers. Structural injuries were absent at both basal and stress condition in KI mice carrying c.674G>A (R225Q); however, this variant significantly prolonged PR intervals at baseline without affecting other ECG parameters, which was linked to decreased peak sodium current density in KI cardiomyocytes. Histological analysis of the atrioventricular node did not show any evidences of cell damages. CONCLUSION: Our results suggest that the iDCM-related SCN5A variants in the DI-S4 could predispose electrical disorders by reducing peak sodium current density.

Mitochondrial aldehyde dehydrogenase-2 deficiency compromises therapeutic effect of ALDH bright cell on peripheral ischemia.

The autologous ALDH bright (ALDHbr) cell therapy for ischemic injury is clinically safe and effective, while the underlying mechanism remains elusive. Here, we demonstrated that the glycolysis dominant metabolism of ALDHbr cells is permissive to restore blood flow in an ischemic hind limb model compared with bone marrow mononuclear cells (BMNCs). PCR array analysis showed overtly elevated Aldh2 expression of ALDHbr cells following hypoxic challenge. Notably, ALDHbr cells therapy induced blood flow recovery in this model was reduced in case of ALDH2 deficiency. Moreover, significantly reduced glycolysis flux and increased reactive oxygen species (ROS) levels were detected in ALDHbr cell from Aldh2-/- mice. Compromised effect on blood flow recovery was also noticed post transplanting the human ALDHbr cell from ALDH2 deficient patients (GA or AA genotypes) in this ischemic hindlimb mice model. Taken together, our findings illustrate the indispensable role of ALDH2 in maintaining glycolysis dominant metabolism of ALDHbr cell and advocate that patient's Aldh2 genotype is a prerequisite for the efficacy of ALDHbr cell therapy for peripheral ischemia.

Regulation of p53 by jagged1 contributes to angiotensin II-induced impairment of myocardial angiogenesis.

Angiotensin II (AngII) is a major contributor to the development of heart failure, however, the molecular and cellular mechanisms still remain elucidative. Inadequate angiogenesis in myocardium leads to transition from cardiac hypertrophy to dysfunction, this study was therefore conducted to examine the effects of AngII on myocardial angiogenesis and the underlying mechanisms. AngII treatment significantly impaired angiogenetic responses, which were determined by counting the capillaries either in matrigel formed by cultured cardiac microvascular endothelial cells (CMVECs) or in myocardium of mice and by measuring the in vitro and in vivo production of VEGF proteins, and stimulated accumulation and phosphorylation of cytosolic p53 which led to increases in phosphorylated p53 and decreases of hypoxia inducible factor (Hif-1) in nucleus. All of these cellular and molecular events induced by AngII in CEMCs and hearts of mice were largely reduced by a p53 inhibitor, pifithrin-α (PFT-α). Interestingly, AngII stimulated the upregulation of Jagged1, a ligand of Notch, but it didn't affect the expression of Delta-like 4 (Dll-4), another ligand of Notch. Inhibition of p53 by PFT-α partly abolished this effect of AngII. Further experiments showed that knockdown ofJagged1 by addition of siRNA to cultured CMVECs dramatically declined AngII-stimulated accumulation and phosphorylation of p53 in cytosol, upregulation of phosphorylated p53 and downregulation of Hif-1 expression in nucleus, decrease of VEGF production and impairment of capillary-like tube formation by the cells. Our data collectively suggest that AngII impairs myocardial angiogenetic responses through p53-dependent downregulation of Hif-1 which is regulated by Jagged1/Notch1 signaling.

AngiotensinII preconditioning promotes angiogenesis in vitro via ERKs phosphorylation.

AngiotensinII (AngII) is involved in not only the formation of cardiac hypertrophy but also the development of cardiac remodeling both of which are associated with myocardial angiogenesis. This study was therefore performed to clarify the effects of AngII on the formation of vasculatures by cultured cardiac microvascular endothelial cells (CMVECs) after a long-period stimulation with or without the AngII preconditioning. Incubation with AngII for 18 hrs significantly impaired the formation of capillary-like tubes comparing to that without AngII. CMVECs with AngII pretreatment for 5 and 10 min formed more capillary-like tubes than those without AngII pretreatment, suggesting that preconditioning with AngII at a lower dose for a short period could prevent the further damage of CMVECs by a higher concentration of AngII. Moreover, AngII (10(-7) M) stimulation for 5 and 10 min significantly induced the increase in extracellular signal-regulated protein kinases (ERKs) phosphorylation, and an ERKs inhibitor, PD98059, abrogated the increase in the formation of capillary-like tubes induced by the AngII-pretreatment. In conclusion, preconditioning with a lower concentration of AngII for a short period prevents the subsequent impairment of CMVECs by a higher dose of AngII, at least in part, through the increase in ERKs phosphorylation.