Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

In ferroptosis, the roles of mitochondria have been controversial. To explore the role of mitochondrial events in ferroptosis, we employed mitochondrial DNA-depleted ρ⁰ cells that are resistant to cell death due to enhanced expression of antioxidant enzymes. Expression of mitochondrial-type GPx4 (mGPx4) but no other forms of GPx4 was increased in SK-Hep1 ρ⁰ cells. Likely due to high mGPx4 expression, SK-Hep1 ρ⁰ cells were resistant to ferroptosis by erastin inhibiting xCT channel. In contrast, SK-Hep1 ρ⁰ cells were susceptible to cell death by a high concentration of RSL3 imposing ferroptosis by GPx4 inhibition. Accumulation of cellular ROS and oxidized lipids was observed in erastin- or RSL3-treated SK-Hep1 ρ⁺ cells but not in erastin-treated SK-Hep1 ρ⁰ cells. Mitochondrial ROS and mitochondrial peroxidized lipids accumulated in SK-Hep1 ρ⁺ cells not only by RSL3 but also by erastin acting on xCT on the plasma membrane. Mitochondrial ROS quenching inhibited SK-Hep1 ρ⁺ cell death by erastin or a high dose of RSL3, suggesting a critical role of mitochondrial ROS in ferroptosis. Ferroptosis by erastin or RSL3 was inhibited by a more than 20-fold lower concentration of MitoQ, a mitochondrial ROS quencher, compared to DecylQ, a non-targeting counterpart. Ferroptosis of SK-Hep1 ρ⁺ cells by erastin or RSL3 was markedly inhibited by a VDAC inhibitor, accompanied by significantly reduced accumulation of mitochondria ROS, total peroxidized lipids, and mitochondrial peroxidized lipids, strongly supporting the role of mitochondrial events in ferroptotic death and that of VDAC in mitochondrial steps of ferroptosis induced by erastin or RSL3. SK-Hep1 ρ⁺ cell ferroptosis by sorafenib was also suppressed by mitochondrial ROS quenchers, accompanied by abrogation of sorafenib-induced mitochondrial ROS and mitochondrial peroxidized lipid accumulation. These results suggest that SK-Hep1 ρ⁰ cells are resistant to ferroptosis due to upregulation of mGPx4 expression and mitochondrial events could be the ultimate step in determining final cell fate.

DOI： 10.1038/s41420-022-01199-8

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Other Link： https://www.nature.com/articles/s41420-022-01199-8

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Circulation Heart Failure  

BACKGROUND: Dilated cardiomyopathy (DCM) is a life-threatening disease, resulting in refractory heart failure. An immune disorder underlies the pathophysiology associated with heart failure progression. Invariant natural killer T (iNKT) cell activation is a prospective therapeutic strategy for ischemic heart disease. However, its efficacy in nonischemic cardiomyopathy, such as DCM, remains to be elucidated, and the feasible modality for iNKT cell activation in humans is yet to be validated. METHODS: Dendritic cells isolated from human volunteers were pulsed with α-galactosylceramide ex vivo, which were used as α-galactosylceramide-pulsed dendritic cells (αGCDCs). We treated DCM mice harboring mutated troponin TΔK210/ΔK210 with αGCDCs and evaluated the efficacy of iNKT cell activation on heart failure in DCM mice. Furthermore, we investigated the molecular basis underlying its therapeutic effects in these mice and analyzed primary cardiac cells under iNKT cell-secreted cytokines. RESULTS: The number of iNKT cells in the spleens of DCM mice was reduced compared with that in wild-type mice, whereas αGCDC treatment activated iNKT cells, prolonged survival of DCM mice, and prevented decline in the left ventricular ejection fraction for 4 weeks, accompanied by suppressed interstitial fibrosis. Mechanistically, αGCDC treatment suppressed TGF (transforming growth factor)-β signaling and expression of fibrotic genes and restored vasculature that was impaired in DCM hearts by upregulating angiopoietin 1 (Angpt1) expression. Consistently, IFNγ (interferon gamma) suppressed TGF-β-induced Smad2/3 signaling and the expression of fibrotic genes in cardiac fibroblasts and upregulated Angpt1 expression in cardiomyocytes via Stat1. CONCLUSIONS: Immunomodulatory cell therapy with αGCDCs is a novel therapeutic strategy for heart failure in DCM.

DOI： 10.1161/CIRCHEARTFAILURE.122.009366

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Jacc Basic to Translational Science  

Ischemia-reperfusion (I/R) injury is a promising therapeutic target to improve clinical outcomes after acute myocardial infarction. Ferroptosis, triggered by iron overload and excessive lipid peroxides, is reportedly involved in I/R injury. However, its significance and mechanistic basis remain unclear. Here, we show that glutathione peroxidase 4 (GPx4), a key endogenous suppressor of ferroptosis, determines the susceptibility to myocardial I/R injury. Importantly, ferroptosis is a major mode of cell death in I/R injury, distinct from mitochondrial permeability transition (MPT)-driven necrosis. This suggests that the use of therapeutics targeting both modes is an effective strategy to further reduce the infarct size and thereby ameliorate cardiac remodeling after I/R injury. Furthermore, we demonstrate that heme oxygenase 1 up-regulation in response to hypoxia and hypoxia/reoxygenation degrades heme and thereby induces iron overload and ferroptosis in the endoplasmic reticulum (ER) of cardiomyocytes. Collectively, ferroptosis triggered by GPx4 reduction and iron overload in the ER is distinct from MPT-driven necrosis in both in vivo phenotype and in vitro mechanism for I/R injury. The use of therapeutics targeting ferroptosis in conjunction with cyclosporine A can be a promising strategy for I/R injury.

DOI： 10.1016/j.jacbts.2022.03.012

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Cardiovascular Pharmacology  

ABSTRACT: Doxorubicin (DOX) is an effective anti-cancer agent for various malignancies. Nevertheless, it has a side effect of cardiotoxicity, referred to as doxorubicin-induced cardiomyopathy (DIC), that is associated with a poorer prognosis. This cardiotoxicity limits the clinical use of DOX as a therapeutic agent for malignancies. Recently, ferroptosis, a form of regulated cell death induced by the accumulation of lipid peroxides, has been recognized as a major pathophysiology of DIC. Ethoxyquin is a lipophilic antioxidant widely used for food preservation and thus may be a potential therapeutic drug for preventing DIC. However, the efficacy of ethoxyquin against ferroptosis and DIC remains to be fully elucidated. Here, we investigated the inhibitory action of ethoxyquin against GPx4-deficient ferroptosis and its therapeutic efficacy against DOX-induced cell death in cultured cardiomyocytes and cardiotoxicity in a murine model of DIC. In cultured cardiomyocytes, ethoxyquin treatment effectively prevented GPx4-deficient ferroptosis. Ethoxyquin also prevented DOX-induced cell death, accompanied by the suppression of malondialdehyde (MDA) and mitochondrial lipid peroxides, which were induced by DOX. Furthermore, ethoxyquin significantly prevented DOX-induced cell death without any suppression of caspase cleavages representing apoptosis. In DIC mice, ethoxyquin treatment ameliorated cardiac impairments, such as contractile dysfunction and myocardial atrophy, and lung congestion. Ethoxyquin also suppressed serum lactate dehydrogenase and creatine kinase activities, decreased the levels of lipid peroxides such as MDA and acrolein, inhibited cardiac fibrosis, and reduced TUNEL-positive cells in the hearts of DIC mice. Collectively, ethoxyquin is a competent antioxidant for preventing ferroptosis in DIC and can be its prospective therapeutic drug.

DOI： 10.1097/FJC.0000000000001328

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Cardiovascular Drugs and Therapy  

PURPOSE: Cardiac rupture is a fatal complication following myocardial infarction (MI). An increase in heart rate (HR) is reportedly an independent risk factor for cardiac rupture during acute MI. However, the role of HR reduction in cardiac rupture after MI remains to be fully elucidated. We aimed to evaluate the therapeutic efficacy of HR reduction with ivabradine (IVA) on post-MI cardiac rupture in mice. METHODS: We induced MI in mice by ligating the left anterior descending coronary artery. Subsequently, we subcutaneously implanted osmotic pumps filled with IVA solution or vehicle (Veh) in the surviving MI mice at 24 h postoperatively. We biochemically analyzed the myocardium on day 5, additionally observed the mice for 10 days, and analyzed the rates of cardiac rupture and non-cardiac rupture death, and survival after MI. RESULTS: HR was significantly lower in the IVA-treated mice, whereas blood pressure was comparable between the two groups. Compared to the Veh-treated mice, apoptosis was significantly reduced in the MI border zone in the IVA-treated mice. Although there were no differences in the infarct size of the surviving MI mice between the two groups, HR reduction with IVA significantly reduced cardiac rupture (rupture rate 26 and 8% in the Veh-treated and IVA-treated groups, respectively) and improved survival after MI. CONCLUSION: Our findings suggest that HR reduction with IVA prevents cardiac rupture after MI. This may be particularly effective in MI patients with a high HR who are either unable to adequately tolerate β-blockers or whose HR remains high despite receiving β-blockers.

DOI： 10.1007/s10557-020-07123-5

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Language：English   Publishing type：Research paper (scientific journal)  

AIMS: Individual risk stratification is a fundamental strategy in managing patients with heart failure (HF). Artificial intelligence, particularly machine learning (ML), can develop superior models for predicting the prognosis of HF patients, and administrative claim data (ACD) are suitable for ML analysis because ACD is a structured database. The objective of this study was to analyse ACD using an ML algorithm, predict the 1 year mortality of patients with HF, and finally develop an easy-to-use prediction model with high accuracy using the top predictors identified by the ML algorithm. METHODS AND RESULTS: Machine learning-based prognostic prediction models were developed from the ACD on 10 175 HF patients from the Japanese Registry of Acute Decompensated Heart Failure with 17% mortality during 1 year follow-up. The top predictors for prognosis in HF were identified by the permutation feature importance technique, and an easy-to-use prediction model was developed based on these predictors. The c-statistics and Brier scores of the developed ML-based models were compared with those of conventional risk models: Seattle Heart Failure Model (SHFM) and Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC). A voting classifier algorithm (ACD-VC) achieved the highest c-statistics among the six ML algorithms. The permutation feature importance technique enabled identification of the top predictors such as Barthel index, age, body mass index, duration of hospitalization, last hospitalization, renal disease, and non-loop diuretics use (feature importance values were 0.054, 0.025, 0.010, 0.005, 0.005, 0.004, and 0.004, respectively). Upon combination of some of the predictors that can be assessed from a brief interview, the Simple Model by ARTificial intelligence for HF risk stratification (SMART-HF) was established as an easy-to-use prediction model. Compared with the conventional models, SMART-HF achieved a higher c-statistic {ACD-VC: 0.777 [95% confidence interval (CI) 0.751-0.803], SMART-HF: 0.765 [95% CI 0.739-0.791], SHFM: 0.713 [95% CI 0.684-0.742], MAGGIC: 0.726 [95% CI 0.698-0.753]} and better Brier scores (ACD-VC: 0.121, SMART-HF: 0.124, SHFM: 0.139, MAGGIC: 0.130). CONCLUSIONS: The ML model based on ACD predicted the 1 year mortality of HF patients with high accuracy, and SMART-HF along with the ML model achieved superior performance to that of the conventional risk models. The SMART-HF model has the clear merit of easy operability even by non-healthcare providers with a user-friendly online interface (https://hfriskcalculator.herokuapp.com/). Risk models developed using SMART-HF may provide a novel modality for risk stratification of patients with HF.

DOI： 10.1002/ehf2.13556

Language：English   Publishing type：Research paper (scientific journal)  

Background Apoptosis plays a pivotal role in cardiac rupture after myocardial infarction (MI), and p53 is a key molecule in apoptosis during cardiac rupture. Hif-1α (hypoxia-inducible factor-1α), upregulated under hypoxia, is a known p53 inducer. However, the role of Hif-1α in the regulatory mechanisms underlying p53 upregulation, apoptosis, and cardiac rupture after MI is unclear. Methods and Results We induced MI in mice by ligating the left anterior descending artery. Hif-1α and p53 expressions were upregulated in the border zone at day 5 after MI, accompanied by apoptosis. In rat neonatal cardiomyocytes, treatment with cobalt chloride (500 μmol/L), which mimics severe hypoxia by inhibiting PHD (prolyl hydroxylase domain-containing protein), increased Hif-1α and p53, accompanied by myocyte death with caspase-3 cleavage. Silencing Hif-1α or p53 inhibited caspase-3 cleavage, and completely prevented myocyte death under PHD inhibition. In cardiac-specific Hif-1α hetero-knockout mice, expression of p53 and cleavage of caspase-3 and poly (ADP-ribose) polymerase were reduced, and apoptosis was suppressed on day 5. Furthermore, the cleavage of caspase-8 and IL-1β (interleukin-1β) was also suppressed in hetero knockout mice, accompanied by reduced macrophage infiltration and matrix metalloproteinase/tissue inhibitor of metalloproteinase activation. Although there was no intergroup difference in infarct size, the cardiac rupture and survival rates were significantly improved in the hetero knockout mice until day 10 after MI. Conclusions Hif-1α plays a pivotal role in apoptosis, inflammation, and cardiac rupture after MI, in which p53 is a critical mediator, and may be a prospective therapeutic target for preventing cardiac rupture.

DOI： 10.1161/JAHA.121.020895

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Ischemic preconditioning (IPC) is an effective procedure to protect against ischemia/reperfusion (I/R) injury. Hypoxia-inducible factor-1α (Hif-1α) is a key molecule in IPC, and roxadustat (RXD), a first-in-class prolyl hydroxylase domain-containing protein inhibitor, has been recently developed to treat anemia in patients with chronic kidney disease. Thus, we investigated whether RXD pretreatment protects against I/R injury.Methods and Results:RXD pretreatment markedly reduced the infarct size and suppressed plasma creatinine kinase activity in a murine I/R model. Analysis of oxygen metabolism showed that RXD could produce ischemic tolerance by shifting metabolism from aerobic to anaerobic respiration. CONCLUSIONS: RXD pretreatment may be a novel strategy against I/R injury.

DOI： 10.1253/circj.CJ-19-1039

Language：English   Publishing type：Research paper (scientific journal)  

Doxorubicin (DOX), a chemotherapeutic agent, induces a cardiotoxicity referred to as doxorubicin-induced cardiomyopathy (DIC). This cardiotoxicity often limits chemotherapy for malignancies and is associated with poor prognosis. However, the molecular mechanism underlying this cardiotoxicity is yet to be fully elucidated. Here, we show that DOX downregulated glutathione peroxidase 4 (GPx4) and induced excessive lipid peroxidation through DOX-Fe2+ complex in mitochondria, leading to mitochondria-dependent ferroptosis; we also show that mitochondria-dependent ferroptosis is a major cause of DOX cardiotoxicity. In DIC mice, the left ventricular ejection fraction was significantly impaired, and fibrosis and TUNEL+ cells were induced at day 14. Additionally, GPx4, an endogenous regulator of ferroptosis, was downregulated, accompanied by the accumulation of lipid peroxides, especially in mitochondria. These cardiac impairments were ameliorated in GPx4 Tg mice and exacerbated in GPx4 heterodeletion mice. In cultured cardiomyocytes, GPx4 overexpression or iron chelation targeting Fe2+ in mitochondria prevented DOX-induced ferroptosis, demonstrating that DOX triggered ferroptosis in mitochondria. Furthermore, concomitant inhibition of ferroptosis and apoptosis with ferrostatin-1 and zVAD-FMK fully prevented DOX-induced cardiomyocyte death. Our findings suggest that mitochondria-dependent ferroptosis plays a key role in progression of DIC and that ferroptosis is the major form of regulated cell death in DOX cardiotoxicity.

DOI： 10.1172/jci.insight.132747

Language：English   Publishing type：Research paper (scientific journal)  

Dehydrogenase/reductase member 7C (DHRS7C) is a newly identified NAD/NADH-dependent dehydrogenase that is expressed in cardiac and skeletal muscle and localized in the endoplasmic/sarcoplasmic reticulum (ER/SR). However, its functional role in muscle cells remains to be fully elucidated. Here, we investigated the role of DHRS7C by analyzing mouse C2C12 myoblasts deficient in DHRS7C (DHRS7C-KO cells), overexpressing wild-type DHRS7C (DHRS7C-WT cells), or expressing mutant DHRS7C [DHRS7C-Y191F or DHRS7C-K195Q cells, harboring point mutations in the NAD/NADH-dependent dehydrogenase catalytic core domain (YXXXK)]. DHRS7C expression was induced as C2C12 myoblasts differentiated into mature myotubes, whereas DHRS7C-KO myotubes exhibited enlarged cellular morphology after differentiation. Notably, both DHRS7C-Y191F and DHRS7C-K195Q cells also showed similar enlarged cellular morphology, suggesting that the NAD/NADH-dependent dehydrogenase catalytic core domain is pivotal for DHRS7C function. In DHRS7C-KO, DHRS7C-Y191F, and DHRS7C-K195Q cells, the resting level of cytosolic Ca2+ and total amount of Ca2+ storage in the ER/SR were significantly higher than those in control C2C12 and DHRS7C-WT cells after differentiation. Additionally, Ca2+ release from the ER/SR induced by thapsigargin and 4-chloro-m-cresol was augmented in these cells and calpain, a calcium-dependent protease, was significantly activated in DHRS7C-KO, DHRS7C-Y191F, and DHRS7C-K195Q myotubes, consistent with the higher resting level of cytosolic Ca2+ concentration and enlarged morphology after differentiation. Furthermore, treatment with a calpain inhibitor abolished the enlarged cellular morphology. Taken together, our findings suggested that DHRS7C maintains intracellular Ca2+ homeostasis involving the ER/SR and that functional loss of DHRS7C leads to Ca2+ overload in the cytosol and ER/SR, resulting in enlarged cellular morphology via calpain activation.

DOI： 10.1152/ajpcell.00090.2016

Language：English   Publishing type：Research paper (scientific journal)  

Cardiac rupture is a fatal complication after myocardial infarction (MI). However, the detailed mechanism underlying cardiac rupture after MI remains to be fully elucidated. In this study, we investigated the role of mitochondrial DNA (mtDNA) and mitochondria in the pathophysiology of cardiac rupture by analyzing Twinkle helicase overexpression mice (TW mice). Twinkle overexpression increased mtDNA copy number approximately twofold and ameliorated ischemic cardiomyopathy at day 28 after MI. Notably, Twinkle overexpression markedly prevented cardiac rupture and improved post-MI survival, accompanied by the suppression of MMP-2 and MMP-9 in the MI border area at day 5 after MI when cardiac rupture frequently occurs. Additionally, these cardioprotective effects of Twinkle overexpression were abolished in transgenic mice overexpressing mutant Twinkle with an in-frame duplication of amino acids 353-365, which resulted in no increases in mtDNA copy number. Furthermore, although apoptosis and oxidative stress were induced and mitochondria were damaged in the border area, these injuries were improved in TW mice. Further analysis revealed that mitochondrial biogenesis, including mtDNA copy number, transcription, and translation, was severely impaired in the border area at day 5 In contrast, Twinkle overexpression maintained mtDNA copy number and restored the impaired transcription and translation of mtDNA in the border area. These results demonstrated that Twinkle overexpression alleviated impaired mitochondrial biogenesis in the border area through maintained mtDNA copy number and thereby prevented cardiac rupture accompanied by the reduction of apoptosis and oxidative stress, and suppression of MMP activity.

DOI： 10.1152/ajpheart.00044.2016

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/eurheartj/ehv764

Language：English   Publishing type：Research paper (scientific journal)  

The heart has two major modalities of hypertrophy in response to hemodynamic loads: concentric and eccentric hypertrophy caused by pressure and volume overload (VO), respectively. However, the molecular mechanism of eccentric hypertrophy remains poorly understood. Here we demonstrate that the Akt-mammalian target of rapamycin (mTOR) axis is a pivotal regulator of eccentric hypertrophy during VO. While mTOR in the heart was activated in a left ventricular end-diastolic pressure (LVEDP)-dependent manner, mTOR inhibition suppressed eccentric hypertrophy and induced cardiac atrophy even under VO. Notably, Akt was ubiquitinated and phosphorylated in response to VO, and blocking the recruitment of Akt to the membrane completely abolished mTOR activation. Various growth factors were upregulated during VO, suggesting that these might be involved in Akt-mTOR activation. Furthermore, the rate of eccentric hypertrophy progression was proportional to mTOR activity, which allowed accurate estimation of eccentric hypertrophy by time-integration of mTOR activity. These results suggested that the Akt-mTOR axis plays a pivotal role in eccentric hypertrophy, and mTOR activity quantitatively determines the rate of eccentric hypertrophy progression. As eccentric hypertrophy is an inherent system of the heart for regulating cardiac output and LVEDP, our findings provide a new mechanistic insight into the adaptive mechanism of the heart.

DOI： 10.1038/srep15881

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Mitochondrial DNA (mtDNA) copy number decreases in animal and human heart failure (HF), yet its role in cardiomyocytes remains to be elucidated. Thus, we investigated the cardioprotective function of increased mtDNA copy number resulting from the overexpression of human transcription factor A of mitochondria (TFAM) or Twinkle helicase in volume overload (VO)-induced HF. METHODS AND RESULTS: Two strains of transgenic (TG) mice, one overexpressing TFAM and the other overexpressing Twinkle helicase, exhibit an approximately 2-fold equivalent increase in mtDNA copy number in heart. These TG mice display similar attenuations in eccentric hypertrophy and improved cardiac function compared to wild-type (WT) mice without any deterioration of mitochondrial enzymatic activities in response to VO, which was accompanied by a reduction in matrix-metalloproteinase (MMP) activity and reactive oxygen species after 8 weeks of VO. Moreover, acute VO-induced MMP-2 and MMP-9 upregulation was also suppressed at 24 h in both TG mice. In isolated rat cardiomyocytes, mitochondrial reactive oxygen species (mitoROS) upregulated MMP-2 and MMP-9 expression, and human TFAM (hTFAM) overexpression suppressed mitoROS and their upregulation. Additionally, mitoROS were equally suppressed in H9c2 rat cardiomyoblasts that overexpress hTFAM or rat Twinkle, both of which exhibit increased mtDNA copy number. Furthermore, mitoROS and mitochondrial protein oxidation from both TG mice were suppressed compared to WT mice. CONCLUSIONS: The overexpression of TFAM or Twinkle results in increased mtDNA copy number and facilitates cardioprotection associated with limited mitochondrial oxidative stress. Our findings suggest that increasing mtDNA copy number could be a useful therapeutic strategy to target mitoROS in HF.

DOI： 10.1371/journal.pone.0119687

Language：Others   Publishing type：Research paper (scientific journal)  

Diffuse alveolar hemorrhage after percutaneous coronary intervention is a rare complication that has been mostly reported in association with glycoprotein IIb/IIIa inhibitors. We herein report a case of a 64-year-old male who developed a diffuse pulmonary hemorrhage after coronary stent implantation for ST-elevation myocardial infarction. Diagnostic bronchoscopy determined the hemorrhage to be a bland pulmonary hemorrhage, and this pattern suggested that combination therapy with aspirin and ticlopidine was therefore the most likely cause. The combination of aspirin and thienopyridine agents is a routine therapeutic protocol for patients after coronary stent implantation. Therefore, physicians should be aware that this dual antiplatelet therapy might sometimes induce fatal complications. © 2011 Elsevier Inc.

DOI： 10.1016/j.carrev.2011.03.003

Publisher：Hypertension Research  

The pathogenesis of heart failure with preserved ejection fraction (HFpEF) remains unclear, and effective treatments are limited. HFpEF is more prevalent in females, indicating potential gender differences in its pathogenesis. However, no female HFpEF model animals have been established. Hypertension is a major contributor to HFpEF, and sympathetic activation is thought to play a role in both conditions. This study aimed to establish a female HFpEF model using hypertensive Dahl salt-sensitive rats and to assess the presence of sympathetic activation. Seven-week-old female Dahl salt-sensitive rats were fed an 8% high-salt diet (HS group, n = 6), while a low-salt diet group (LS group, n = 9) served as controls. The HS group exhibited increased systolic blood pressure and heart rate. Echocardiography revealed an increased left ventricular (LV) wall thickness, a decreased E/A ratio, and an increased E/e’ ratio, all indicative of diastolic dysfunction without reduced LV ejection fraction. Additionally, the HS group showed elevated LV end-diastolic pressure, LV weight, and lung weight, along with histological cardiomyocyte hypertrophy and interstitial fibrosis. Gene expression markers for cardiac hypertrophy and fibrosis were also increased. Renal function was significantly impaired, and plasma norepinephrine levels were elevated, consistent with heightened pre-sympathetic neuronal activity in the brain. In conclusion, high salt loading from 7 weeks of age in female Dahl salt-sensitive rats induced hypertensive HFpEF phenotypes with LV hypertrophy and fibrosis, and sympathetic activation by 16 to 19 weeks of age. This model provides a valuable tool for studying HFpEF pathophysiology in women. (Figure presented.)

DOI： 10.1038/s41440-024-02025-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scientific Reports  

Intensive care unit-acquired weakness (ICU-AW) is recognized as newly-acquired bilateral muscle weakness, which is a complication of critical illness in the ICU; however, there are no reports on the pathogenesis and early predictors of ICU-AW specifically associated with cardiogenic shock (CS). Therefore, this study aimed to investigate the clinical characteristics of ICU-AW in patients with CS requiring mechanical circulatory support (MCS). This study was a single-center, prospective, and observational study. Patients aged 16 years and older who underwent MCS for CS were included. ICU-AW was diagnosed based on Medical Research Council (MRC) score after awakening. The ICU-AW group included patients with the MRC score < 48 points, and the non-ICU-AW group included those with ≥ 48 points. Twenty-eight cases were enrolled on admission and MRC score was evaluated in 23 cases after awakening. Eleven patients were included in the non-ICU-AW group and 12 patients (52%) were in the ICU-AW group. The ICU-AW group showed a higher prevalence of extracorporeal membrane oxygenation and ventilator use. Creatine kinase, troponin T, interleukin (IL)-15 levels on admission were significantly higher, whereas hemoglobin and albumin levels were significantly lower in the ICU-AW group. A strong negative correlation was observed between the initial MRC scores and IL-15 levels. ICU-AW occurred 52% of patients with CS using MCS, indicating the significance of recognizing and managing this complication for those patients. In addition, IL-15 can be a potential biomarker for the early prediction of ICU-AW.

DOI： 10.1038/s41598-025-87381-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Life Science Alliance  

Mitochondrial transcription factor A, TFAM, is essential for mitochondrial function. We examined the effects of overexpressing the TFAM gene in mice. Two types of transgenic mice were created: TFAM heterozygous (TFAM Tg) and homozygous (TFAM Tg/Tg) mice. TFAM Tg/Tg mice were smaller and leaner notably with longer lifespans. In skeletal muscle, TFAM overexpression changed gene and protein expression in mitochondrial respiratory chain complexes, with down-regulation in complexes 1, 3, and 4 and up-regulation in complexes 2 and 5. The iMPAQT analysis combined with metabolomics was able to clearly separate the metabolomic features of the three types of mice, with increased degradation of fatty acids and branched-chain amino acids and decreased glycolysis in homozygotes. Consistent with these observations, comprehensive gene expression analysis revealed signs of mitochondrial stress, with elevation of genes associated with the integrated and mitochondrial stress responses, including Atf4, Fgf21, and Gdf15. These found that mitohormesis develops and metabolic shifts in skeletal muscle occur as an adaptive strategy.

DOI： 10.26508/lsa.202302498

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Biological and Pharmaceutical Bulletin  

Recently, mitochondrial dysfunction has gained attention as a causative factor in the pathogenesis and progression of age-related macular degeneration (AMD). Mitochondrial damage plays a key role in metabolism and disrupts the balance of intracellular metabolic pathways, such as oxidative phosphorylation (OXPHOS) and glycolysis. In this study, we focused on oxidized low-density lipoprotein (ox-LDL), a major constituent of drusen that accumulates in the retina of patients with AMD, and investigated whether it could be a causative factor for metabolic alterations in retinal pigment epithelial (RPE) cells. We found that prolonged exposure to ox-LDL induced changes in fatty acid β-oxidation (FAO), OXPHOS, and glycolytic activity and increased the mitochondrial reactive oxygen species production in RPE cells. Notably, the effects on metabolic alterations varied with the concentration and duration of ox-LDL treatment. In addition, we addressed the limitations of using ARPE-19 cells for retinal disease research by highlighting their lower barrier function and FAO activity compared to those of induced pluripotent stem cell-derived RPE cells. Our findings can aid in the elucidation of mechanisms underlying the metabolic alterations in AMD.

DOI： 10.1248/bpb.b23-00849

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：European Journal of Preventive Cardiology  

AIM: Exercise intolerance is a clinical feature of patients with heart failure (HF). Cardiopulmonary exercise testing (CPET) is the first-line examination for assessing exercise capacity in patients with HF. However, the need for extensive experience in assessing anaerobic threshold (AT) and the potential risk associated with the excessive exercise load when measuring peak oxygen uptake (peak VO2) limit the utility of CPET. This study aimed to use deep-learning approaches to identify AT in real-time during testing (defined as real-time AT) and to predict peak VO2 at real-time AT. METHODS: This study included the time-series data of CPET recorded at the Department of Cardiovascular Medicine, Kyushu University Hospital. Two deep neural network models were developed:1) to estimate the AT probability using breath-by-breath data, and 2) to predict peak VO2 using the data at the real-time AT. RESULTS: The eligible CPET were 1,472 records in 1,053 participants aged 18-90 years and 20% were used for model evaluation. The developed model identified real-time AT with 0.82 for correlation coefficient (Corr) and 1.20 mL/kg/min for mean absolute error (MAE), and the corresponding AT time with 0.86 for Corr and 0.66 min for MAE. The peak VO2 prediction model achieved 0.87 for Corr and 2.25 mL/kg/min for MAE. CONCLUSION: Deep-learning models for real-time CPET analysis can accurately identify AT and predict peak VO2. The developed models can be a competent assistant system to assess the patient's condition in real-time, expanding CPET utility.

DOI： 10.1093/eurjpc/zwad375

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Oxidative stress is hypothesized to drive the progression of age-related macular degeneration (AMD). Retinal pigment epithelial (RPE) cell layer is important for supporting the function of retina and is particularly susceptible to oxidative stress-induced cell death. How RPE cells die in AMD, especially in geographic atrophy (GA), a late stage of dry AMD, is still controversial. The goal of this study is to compare the features and mechanisms of RPE cell death induced by different oxidative stresses, to identify potential universal therapeutic targets for GA. RPE cell death was induced both in vitro and ex vivo by 4-Hydroxynonenal (4-HNE), a major product of lipid peroxidation, sodium iodate (NaIO<inf>3</inf>) that has been widely used to model RPE cell death in dry AMD, a ferroptosis inducer RAS-selective lethal 3 (RSL3) or a necroptosis inducer shikonin. We found that RPE necroptosis and ferroptosis show common and distinct features. Common features include receptor-interacting protein kinase (RIPK)1/RIPK3 activation and lipid reactive oxygen species (ROS) accumulation, although lipid ROS accumulation is much milder during necroptosis. This supports cross talk between RPE ferroptosis and necroptosis pathways and is consistent with the rescue of RPE necroptosis and ferroptosis by RIPK1 inhibitor Necrostatin-1 (Nec-1) or in Ripk3^−/− RPE explants. Distinct feature includes activated mixed lineage kinase domain like pseudokinase (MLKL) that is translocated to the cell membrane during necroptosis, which is not happening in ferroptosis. This is consistent with the failure to rescue RPE ferroptosis by MLKL inhibitor necrosulfonamide (NSA) or in Mlkl^−/− RPE explants. Using this framework, we found that 4-HNE and NaIO<inf>3</inf> induced RPE cell death likely through necroptosis based on the molecular features and the rescuing effect by multiple inhibitors. Our studies suggest that multiple markers and inhibitors are required to distinguish RPE necroptosis and ferroptosis, and that necroptosis inhibitor Nec-1 could be a potential therapeutic compound for GA since it inhibits RIPK1/RIPK3 activation and lipid ROS accumulation occurred in both necroptosis and ferroptosis pathways.

DOI： 10.1016/j.redox.2023.102840

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Jacc Basic to Translational Science  

Doxorubicin (DOX)-induced cardiomyopathy has poor prognosis, and myocardial inflammation is intimately involved in its pathophysiology. The role of invariant natural killer T (iNKT) cells has not been fully determined in this disease. We here demonstrated that activation of iNKT cells by α-galactosylceramide (GC) attenuated DOX-induced cardiomyocyte death and cardiac dysfunction. αGC increased interferon (IFN)-γ and phosphorylation of signal transducers and activators of transcription 1 (STAT1) and extracellular signal-regulated kinase (ERK). Administration of anti-IFN-γ neutralizing antibody abrogated the beneficial effects of αGC on DOX-induced cardiac dysfunction. These findings emphasize the protective role of iNKT cells in DOX-induced cardiomyopathy via the IFN-γ-STAT1-ERK pathway.

DOI： 10.1016/j.jacbts.2023.02.014

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Jacc Clinical Electrophysiology  

BACKGROUND: Advances in catheter ablation (CA) for atrial fibrillation (AF) have improved the prognosis of patients with heart failure (HF) and AF. However, its optimal timing remains to be fully elucidated. OBJECTIVES: The aim of this study was to investigate the prognostic impact of early CA in patients with HF and AF hospitalized for worsening HF. METHODS: From JROADHF (Japanese Registry of Acute Decompensated Heart Failure) (n = 13,238), patients with HF and AF who underwent CA within 90 days after admission for HF (early CA; n = 103) and those who did not (control; n = 2,683) were identified. Mortality was compared between these groups in the crude cohort, as well as in the propensity-matched cohort (n = 83 in each group). RESULTS: In the crude cohort, all-cause mortality was significantly lower in the early CA group than in the control group (log-rank P < 0.001; HR: 0.38; 95% CI: 0.24-0.60). In the matched cohort, all-cause mortality was likewise significantly lower in the early CA group (log-rank P = 0.014; HR: 0.47; 95% CI: 0.25-0.88). Cardiovascular death and HF mortality were significantly lower in both cohorts (crude: Gray' test: P < 0.001 and P = 0.005; subdistribution HR: 0.28 [95% CI: 0.13-0.63] and HR: 0.31 [95% CI: 0.13-0.75]; matched: Gray's test: P = 0.006 and P = 0.017; subdistribution HR: 0.24 [95% CI: 0.08-0.70] and HR: 0.28 [95% CI: 0.09-0.84], respectively). CONCLUSIONS: In a nationwide representative real-world cohort, CA for AF within 90 days after admission for HF was associated with improved long-term outcomes, including cardiovascular and HF death in patients with HF and AF.

DOI： 10.1016/j.jacep.2023.05.038

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Circulation Research  

BACKGROUND: Mitochondrial DNA (mtDNA)-induced myocardial inflammation is intimately involved in cardiac remodeling. ZBP1 (Z-DNA binding protein 1) is a pattern recognition receptor positively regulating inflammation in response to mtDNA in inflammatory cells, fibroblasts, and endothelial cells. However, the role of ZBP1 in myocardial inflammation and cardiac remodeling remains unclear. The aim of this study was to elucidate the role of ZBP1 in mtDNA-induced inflammation in cardiomyocytes and failing hearts. METHODS: mtDNA was administrated into isolated cardiomyocytes. Myocardial infarctionwas conducted in wild type and ZBP1 knockout mice. RESULTS: We here found that, unlike in macrophages, ZBP1 knockdown unexpectedly exacerbated mtDNA-induced inflammation such as increases in IL (interleukin)-1β and IL-6, accompanied by increases in RIPK3 (receptor interacting protein kinase 3), phosphorylated NF-κB (nuclear factor-κB), and NLRP3 (nucleotide-binding domain and leucine-rich-repeat family pyrin domain containing 3) in cardiomyocytes. RIPK3 knockdown canceled further increases in phosphorylated NF-κB, NLRP3, IL-1β, and IL-6 by ZBP1 knockdown in cardiomyocytes in response to mtDNA. Furthermore, NF-κB knockdown suppressed such increases in NLRP3, IL-1β, and IL-6 by ZBP1 knockdown in response to mtDNA. CpG-oligodeoxynucleotide, a Toll-like receptor 9 stimulator, increased RIPK3, IL-1β, and IL-6 and ZBP1 knockdown exacerbated them. Dloop, a component of mtDNA, but not Tert and B2m, components of nuclear DNA, was increased in cytosolic fraction from noninfarcted region of mouse hearts after myocardial infarction compared with control hearts. Consistent with this change, ZBP1, RIPK3, phosphorylated NF-κB, NLRP3, IL-1β, and IL-6 were increased in failing hearts. ZBP1 knockout mice exacerbated left ventricular dilatation and dysfunction after myocardial infarction, accompanied by further increases in RIPK3, phosphorylated NF-κB, NLRP3, IL-1β, and IL-6. In histological analysis, ZBP1 knockout increased interstitial fibrosis and myocardial apoptosis in failing hearts. CONCLUSIONS: Our study reveals unexpected protective roles of ZBP1 against cardiac remodeling as an endogenous suppressor of mtDNA-induced myocardial inflammation.

DOI： 10.1161/CIRCRESAHA.122.322227

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

The occurrence of diet-induced obesity has been increasing worldwide and has become a major health concern. Mitochondria are densely distributed in brown adipose tissue and are involved in lipid consumption. Therefore, increasing energy expenditure through the activation of brown adipocytes may be a potential therapy for obesity. Our findings showed that mitochondrial transcription factor A (TFAM) homozygous transgenic (TgTg) mice had highly activated brown adipocytes and increased expression of oxidative phosphorylation, leading to resistance to obesity. Transplantation models of TFAM-expressing brown adipocytes could mimic the phenotype of TFAM TgTg mice, and proving their anti-obesity effect. We found that brown adipocytes secrete exosomes which enable self-activation in an autocrine and paracrine manner. The secretion was enhanced in TFAM TgTg brown adipocytes, resulting in a higher activation. These findings may lead to a promising treatment strategy for obesity through selective stimulation of exosome secretion.

DOI： 10.1016/j.isci.2022.104889

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Esc Heart Failure  

AIMS: Cardiac rehabilitation (CR) is an evidence-based, secondary preventive strategy that improves mortality and morbidity rates in patients with heart failure (HF). However, the implementation and continuation of CR remains unsatisfactory, particularly for outpatients with physical frailty. This study investigated the efficacy and safety of a comprehensive home-based cardiac rehabilitation (HBCR) programme that combines patient education, exercise guidance, and nutritional guidance using information and communication technology (ICT). METHODS AND RESULTS: This study was a single-centre, open-label, randomized, controlled trial. Between April 2020 and November 2020, 30 outpatients with chronic HF (New York Heart Association II-III) and physical frailty were enrolled. The control group (n = 15) continued with standard care, while the HBCR group (n = 15) also received comprehensive, individualized CR, including ICT-based exercise and nutrition guidance using ICT via a Fitbit® device for 3 months. The CR team communicated with each patient in HBCR group once a week via the application messaging tool and planned the training frequency and intensity of training individually for the next week according to each patient's symptoms and recorded pulse data during exercise. Dietitians conducted a nutritional assessment and then provided individual nutritional advice using the picture-posting function of the application. The primary outcome was the change in the 6 min walking distance (6MWD). The participants' mean age was 63.7 ± 10.1 years, 53% were male, and 87% had non-ischaemic heart disease. The observed change in the 6MWD was significantly greater in the HBCR group (52.1 ± 43.9 m vs. -4.3 ± 38.8 m; P < 0.001) at a 73% of adherence rate. There was no significant change in adverse events in either group. CONCLUSIONS: Our comprehensive HBCR programme using ICT for HF patients with physical frailty improved exercise tolerance and improved lower extremity muscle strength in our sample, suggesting management with individualized ICT-based programmes as a safe and effective approach. Considering the increasing number of HF patients with frailty worldwide, our approach provides an efficient method to keep patients engaged in physical activity in their daily life.

DOI： 10.1002/ehf2.13934

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Language：English   Publishing type：Research paper (scientific journal)  

Molecular mechanisms mediating cardiac hypertrophy by glucose metabolism are incompletely understood. Hexosamine biosynthesis pathway (HBP), an accessory pathway of glycolysis, is known to be involved in the attachment of O-linked N-acetylglucosamine motif (O-GlcNAcylation) to proteins, a post-translational modification. We here demonstrate that glutamine-fructose-6-phosphate amidotransferase 2 (GFAT2), a critical HBP enzyme, is a major isoform of GFAT in the heart and is increased in response to several hypertrophic stimuli, including isoproterenol (ISO). Knockdown of GFAT2 suppresses ISO-induced cardiomyocyte hypertrophy, accompanied by suppression of Akt O-GlcNAcylation and activation. Knockdown of GFAT2 does not affect anti-hypertrophic effect by Akt inhibition. Administration of glucosamine, a substrate of HBP, induces protein O-GlcNAcylation, Akt activation, and cardiomyocyte hypertrophy. In mice, 6-diazo-5-oxo-L-norleucine, an inhibitor of GFAT, attenuates ISO-induced protein O-GlcNAcylation, Akt activation, and cardiac hypertrophy. Our results demonstrate that GFAT2 mediates cardiomyocyte hypertrophy by HBP-O-GlcNAcylation-Akt pathway and could be a critical therapeutic target of cardiac hypertrophy.

DOI： 10.1016/j.isci.2021.103517

Language：English   Publishing type：Research paper (scientific journal)  

Special AT-rich sequence binding protein-1 (SATB1) is localized to the nucleus and remodels chromatin structure in T cells. SATB1-deficient CD4 T cells cannot respond to TCR stimulation; however, the cause of this unresponsiveness is to be clarified. Here, we demonstrate that SATB1 is indispensable to proper mitochondrial functioning and necessary for the activation of signal cascades via the TCR in CD4 T cells. Naïve SATB1-deficient CD4 T cells contain fewer mitochondria than WT T cells, as the former do not express mitochondrial transcription factor A (TFAM). Impaired mitochondrial function in SATB1-deficient T cells subverts mitochondrial ROS production and SHP-1 inactivation by constitutive oxidization. Ectopic TFAM expression increases mitochondrial mass and mitochondrial ROS production and rescues defects in the antigen-specific response in the SATB1-deficient T cells. Thus, SATB1 is vital for maintaining mitochondrial mass and function by regulating TFAM expression, which is necessary for TCR signaling.

DOI： 10.26508/lsa.202101093

Language：English   Publishing type：Research paper (scientific journal)  

Nox4 (NADPH [Nicotinamide adenine dinucleotide phosphate] oxidase 4) is a major source of oxidative stress and is intimately involved in cardiac hypertrophy. DPP (Dipeptidyl peptidase)-4 inhibitor has been reported to regulate Nox4 expression in adipose tissues. However, its effects on Nox4 in cardiac hypertrophy are still unclear. We investigated whether DPP-4 inhibitor could ameliorate cardiac hypertrophy by regulating Nox4 and its downstream targets. Ang II (Angiotensin II; 1.44 mg/kg per day) or saline was continuously infused into C57BL/6J mice with or without teneligliptin (a DPP-4 inhibitor, 30 mg/kg per day) in the drinking water for 1 week. Teneligliptin significantly suppressed plasma DPP-4 activity without any significant changing aortic blood pressure or metabolic parameters such as blood glucose and insulin levels. It attenuated Ang II-induced increases in left ventricular wall thickness and the ratio of heart weight to body weight. It also significantly suppressed Ang II-induced increases in Nox4 mRNA, 4-hydroxy-2-nonenal, and phosphorylation of HDAC4 (histone deacetylase 4), a downstream target of Nox4 and a crucial suppressor of cardiac hypertrophy, in the heart. Exendin-3 (150 pmol/kg per minute), a GLP-1 (glucagon-like peptide 1) receptor antagonist, abrogated these inhibitory effects of teneligliptin on Nox4, 4-hydroxy-2-nonenal, phosphorylation of HDAC4, and cardiac hypertrophy. In cultured neonatal cardiomyocytes, exendin-4 (100 nmol/L, 24 hours), a GLP-1 receptor agonist, ameliorated Ang II-induced cardiomyocyte hypertrophy and decreased in Nox4, 4-hydroxy-2-nonenal, and phosphorylation of HDAC4. Furthermore, exendin-4 prevented Ang II-induced decrease in nuclear HDAC4 in cardiomyocytes. In conclusion, GLP-1 receptor stimulation by DPP-4 inhibitor can attenuate Ang II-induced cardiac hypertrophy by suppressing of the Nox4-HDAC4 axis in cardiomyocytes.

DOI： 10.1161/HYPERTENSIONAHA.119.14400

Language：English   Publishing type：Research paper (scientific journal)  

Ca2+/calmodulin-dependent protein kinase II (CaMKII) and nuclear factor-kappa B (NF-κB) play crucial roles in pathogenesis of doxorubicin (DOX)-induced cardiomyopathy. Their activities are regulated by intracellular Ca2+. We hypothesized that blockade of L-type Ca2+ channel (LTCC) could attenuate DOX-induced cardiomyopathy by regulating CaMKII and NF-κB. DOX activated CaMKII and NF-κB through their phosphorylation and increased cleaved caspase 3 in cardiomyocytes. Pharmacological blockade or gene knockdown of LTCC by nifedipine or small interfering RNA, respectively, suppressed DOX-induced phosphorylation of CaMKII and NF-κB and apoptosis in cardiomyocytes, accompanied by decreasing intracellular Ca2+ concentration. Autocamtide 2-related inhibitory peptide (AIP), a selective CaMKII inhibitor, inhibited DOX-induced phosphorylation of NF-κB and cardiomyocyte apoptosis. Inhibition of NF-κB activity by ammonium pyrrolidinedithiocarbamate (PDTC) suppressed DOX-induced cardiomyocyte apoptosis. DOX-treatment (18 mg/kg via intravenous 3 injections over 1 week) increased phosphorylation of CaMKII and NF-κB in mouse hearts. Nifedipine (10 mg/kg/day) significantly suppressed DOX-induced phosphorylation of CaMKII and NF-κB and cardiomyocyte injury and apoptosis in mouse hearts. Moreover, it attenuated DOX-induced left ventricular dysfunction and dilatation. Our findings suggest that blockade of LTCC attenuates DOX-induced cardiomyocyte apoptosis via suppressing intracellular Ca2+ elevation and activation of CaMKII-NF-κB pathway. LTCC blockers might be potential therapeutic agents against DOX-induced cardiomyopathy.

DOI： 10.1038/s41598-019-46367-6

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Hypertension is a major cause of heart failure. Excessive sympathoexcitation in patients with heart failure leads to poor prognosis. Since carotid body denervation (CBD) has been shown to reduce sympathetic nerve activity in animal models of hypertension and heart failure, we examined if bilateral CBD attenuates the progression of hypertensive heart failure and improves survival. METHODS: We randomly allocated Dahl salt-sensitive rats fed a high-salt diet from 6 weeks of age into CBD (n = 31) and sham-operation (SHAM; n = 50) groups, and conducted CBD or SHAM at 7 weeks of age. We examined the time course of 24-hour urinary norepinephrine (uNE) excretion, blood pressure (BP) and the percent fractional shortening assessed by echocardiography, and estimated the pressure-natriuresis relationship at 14 weeks of age. Finally, we assessed hemodynamics, histological findings, and survival at 16 weeks of age. RESULTS: Compared to SHAM, CBD significantly reduced 24-hour uNE at 12, 14, and 16 weeks of age, shifted the pressure-natriuresis relationship leftward without changing its slope, and attenuated the increase in BP. CBD preserved percent fractional shortening (34.2 ± 1.2 vs. 29.1 ± 1.3&#37;, P < 0.01) and lowered left ventricular end-diastolic pressure (5.0 ± 0.9 vs. 9.0 ± 1.4 mm Hg, P < 0.05). Furthermore, CBD significantly attenuated myocardial hypertrophy (P < 0.01) and fibrosis (P < 0.01). Consequently, CBD markedly improved survival (relative risk reduction: 64.8&#37;). CONCLUSIONS: CBD attenuated the progression of hypertension and worsening of heart failure possibly through sympathoinhibition, and markedly improved survival in a rat model of hypertensive heart failure.

DOI： 10.1093/ajh/hpx062

Language：English   Publishing type：Research paper (scientific journal)  

Left ventricular assist device (LVAD) saves lives in patients with severe left ventricular (LV) failure. However, predicting how much LVAD boosts total cardiac output (CO) remains difficult. This study aimed to develop a framework to quantitatively predict the impact of LVAD on hemodynamics. We adopted the circulatory equilibrium framework and incorporated LVAD into the integrated CO curve to derive the circulatory equilibrium. In anesthetized dogs, we ligated left coronary arteries to create LV failure and inserted a centrifugal pump as LVAD. Using CO and right (PRA) and left atrial pressure (PLA) measured before LVAD support, we predetermined the stressed volume (V) and logarithmic slope of right heart CO curve (SR). Next, we initiated LVAD at maximum level and then decreased LVAD flow stepwise while monitoring hemodynamic changes. We predicted LVAD-induced CO and PRA for given PLA from the predetermined SR and V and compared with those measured experimentally. The predicted CO [r2 = 0.907, SE of estimate (SEE) = 5.59 ml·min-1·kg-1, P < 0.001] and PRA (r2 = 0.967, SEE = 0.307 mmHg, P < 0.001) matched well with measured values indicating the validity of the proposed framework. We further conducted simulation using the validated framework to analyze the impact of LVAD on PRA under various right ventricular (RV) functions. It indicated that PRA is relatively insensitive to changes in RV end-systolic elastance or pulmonary arterial resistance, but sensitive to changes in V. In conclusion, the circulatory equilibrium framework predicts quantitatively the hemodynamic impact of LVAD. This knowledge would contribute to safe management of patients with LV failure undergoing LVAD implantation. NEW & NOTEWORTHY: Hemodynamic response to left ventricular assist device (LVAD) has not been quantitatively investigated. This is the first report of quantitative prediction of the hemodynamics on LVAD using circulatory equilibrium framework. The validated framework allows us to simulate the impact of LVAD on right atrial pressure under various right ventricular functions.

DOI： 10.1152/ajpheart.00617.2016

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Left ventricular assist device (LVAD) mechanically unloads the left ventricle (LV). Theoretical analysis indicates that partial LVAD support (p-LVAD), where LV remains ejecting, reduces LV preload while increases afterload resulting from the elevation of total cardiac output and mean aortic pressure, and consequently does not markedly decrease myocardial oxygen consumption (MVO2). In contrast, total LVAD support (t-LVAD), where LV no longer ejects, markedly decreases LV preload volume and afterload pressure, thereby strikingly reduces MVO2. Since an imbalance in oxygen supply and demand is the fundamental pathophysiology of myocardial infarction (MI), we hypothesized that t-LVAD minimizes MVO2 and reduces infarct size in MI. The purpose of this study was to evaluate the differential impact of the support level of LVAD on MVO2 and infarct size in a canine model of ischemia-reperfusion. METHODS: In 5 normal mongrel dogs, we examined the impact of LVAD on MVO2 at 3 support levels: Control (no LVAD support), p-LVAD and t-LVAD. In another 16 dogs, ischemia was induced by occluding major branches of the left anterior descending coronary artery (90 min) followed by reperfusion (300 min). We activated LVAD from the beginning of ischemia until 300 min of reperfusion, and compared the infarct size among 3 different levels of LVAD support. RESULTS: t-LVAD markedly reduced MVO2 (&#37; reduction against CONTROL: -56 ± 9&#37;, p<0.01) whereas p-LVAD did less (-21 ± 14&#37;, p<0.05). t-LVAD markedly reduced infarct size compared to p-LVAD (infarct area/area at risk: CONTROL; 41.8 ± 6.4, p-LVAD; 29.1 ± 5.6 and t-LVAD; 5.0 ± 3.1&#37;, p<0.01). Changes in creatine kinase-MB paralleled those in infarct size. CONCLUSIONS: Total LVAD support that minimizes metabolic demand maximizes the benefit of LVAD in the treatment of acute myocardial infarction.

DOI： 10.1371/journal.pone.0152911

Language：English   Publishing type：Research paper (scientific journal)  

It has been established that vagal nerve stimulation (VNS) benefits patients and/or animals with heart failure. However, the impact of VNS on sympathetic nerve activity (SNA) remains unknown. In this study, we investigated how vagal afferent stimulation (AVNS) impacts baroreflex control of SNA. In 12 anesthetized Sprague-Dawley rats, we controlled the pressure in isolated bilateral carotid sinuses (CSP), and measured splanchnic SNA and arterial pressure (AP). Under a constant CSP, increasing the voltage of AVNS dose dependently decreased SNA and AP. The averaged maximal inhibition of SNA was -28.0 ± 10.3&#37;. To evaluate the dynamic impacts of AVNS on SNA, we performed random AVNS using binary white noise sequences, and identified the transfer function from AVNS to SNA and that from SNA to AP. We also identified transfer functions of the native baroreflex from CSP to SNA (neural arc) and from SNA to AP (peripheral arc). The transfer function from AVNS to SNA strikingly resembled the baroreflex neural arc and the transfer functions of SNA to AP were indistinguishable whether we perturbed ANVS or CSP, indicating that they likely share common central and peripheral neural mechanisms. To examine the impact of AVNS on baroreflex, we changed CSP stepwise and measured SNA and AP responses with or without AVNS. AVNS resets the sigmoidal neural arc downward, but did not affect the linear peripheral arc. In conclusion, AVNS resets the baroreflex neural arc and induces sympathoinhibition in the same manner as the control of SNA and AP by the native baroreflex.

DOI： 10.14814/phy2.12136

Language：English   Publishing type：Research paper (scientific journal)  

Myocardial mitochondrial DNA (mtDNA) copy number decreases in heart failure. In post-myocardial infarction mice, increasing mtDNA copy number by overexpressing mitochondrial transcription factor attenuates mtDNA deficiency and ameliorates pathological remodeling thereby markedly improving survival. However, the functional significance of increased mtDNA copy number in hypertensive heart disease remains unknown. We addressed this question using transgenic mice that overexpress Twinkle helicase (Twinkle; Tg), the mtDNA helicase, and examined whether Twinkle overexpression protects the heart from left ventricular (LV) remodeling and failure after pressure overload created by transverse aortic constriction (TAC). Twinkle overexpression increased mtDNA copy number by 2.2 ± 0.1-fold. Heart weight, LV diastolic volume and wall thickness were comparable between Tg and wild type littermates (WT) at 28 days after TAC operation. LV end-diastolic pressure increased in WT after TAC (8.6 ± 2.8 mmHg), and this increase was attenuated in Tg (4.6 ± 2.6 mmHg). Impaired LV fractional shortening after TAC operation was also suppressed in Tg, as measured by echocardiography (WT: 16.2 ± 7.2&#37; vs Tg: 20.7 ± 6.2&#37;). These LV functional improvements were accompanied by a decrease in interstitial fibrosis (WT: 10.6 ± 1.1&#37; vs Tg: 3.0 ± 0.6&#37;). In in vitro studies, overexpressing Twinkle using an adenovirus vector in cultured cardiac fibroblasts significantly suppressed mRNA of collagen 1a, collagen 3a and connective tissue growth factor, and angiotensin II-induced transforming growth factor β1 expression. The findings suggest that Twinkle overexpression prevents LV function deterioration. In conclusion, Twinkle overexpression increases mtDNA copy number and ameliorates the progression of LV fibrosis and heart failure in a mouse pressure overload model. Increasing mtDNA copy number by Twinkle overexpression could be a novel therapeutic strategy for hypertensive heart disease.

DOI： 10.1371/journal.pone.0067642

CiNii Research

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CiNii Research

Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Symposium, workshop panel (nominated)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Publisher：(株)日本臨床社  

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Language：Japanese   Publisher：(株)日本臨床社  

Language：Japanese   Publisher：(公財)日本応用酵素協会  

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Language：Japanese   Publisher：(公財)先進医薬研究振興財団  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(株)羊土社  

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Language：Japanese   Publisher：(株)羊土社  

Language：Japanese   Publisher：(株)羊土社  

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Publisher：Jci Insight  

The authors recently became aware that the Mito-FerroGreen (MFG) used in this study is not an Fe2+ chelator, but instead reduces Fe2+ via conversion to Fe3+. As MFG mediates reduction of Fe2+ and suppresses ferroptosis, the overall conclusions are not affected. For clarity, the authors have removed references to MFG-mediated chelation throughout, updated the Graphical Abstract, and renumbered the reference list to refer to Hirayama et al. (1) when first describing the use of MFG in the Results section. The text and Graphical Abstract have been updated in the HTML version and PDF. The Journal has also published an online version of the original article with the incorrect statements crossed out and the modified text printed in red (Supplemental File, Redaction). The authors regret the errors.

DOI： 10.1172/jci.insight.169756

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Language：Japanese   Publisher：(公財)日本応用酵素協会  

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J-GLOBAL

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Publisher：Cell Death Discovery  

The original version of this article contained an error. In line 11 of the Introduction, “cholesterol phospholipids” should be “cholesterol hydroperoxide”. The authors apologize for the error. The original article has been corrected.

DOI： 10.1038/s41420-022-01223-x

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Language：Japanese   Publisher：(公社)日本薬学会  

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Language：Japanese   Publisher：(公財)日本応用酵素協会  

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