ZBP1 Protects Against mtDNA-Induced Myocardial Inflammation in Failing Hearts.

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)-1ß 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-1ß, and IL-6 by ZBP1 knockdown in cardiomyocytes in response to mtDNA. Furthermore, NF-κB knockdown suppressed such increases in NLRP3, IL-1ß, and IL-6 by ZBP1 knockdown in response to mtDNA. CpG-oligodeoxynucleotide, a Toll-like receptor 9 stimulator, increased RIPK3, IL-1ß, 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-1ß, 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-1ß, 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.

Succinyl-CoA-based energy metabolism dysfunction in chronic heart failure.

Heart failure (HF) is a leading cause of death and repeated hospitalizations and often involves cardiac mitochondrial dysfunction. However, the underlying mechanisms largely remain elusive. Here, using a mouse model in which myocardial infarction (MI) was induced by coronary artery ligation, we show the metabolic basis of mitochondrial dysfunction in chronic HF. Four weeks after ligation, MI mice showed a significant decrease in myocardial succinyl-CoA levels, and this decrease impaired the mitochondrial oxidative phosphorylation (OXPHOS) capacity. Heme synthesis and ketolysis, and protein levels of several enzymes consuming succinyl-CoA in these events, were increased in MI mice, while enzymes synthesizing succinyl-CoA from α-ketoglutarate and glutamate were also increased. Furthermore, the ADP-specific subunit of succinyl-CoA synthase was reduced, while its GDP-specific subunit was almost unchanged. Administration of 5-aminolevulinic acid, an intermediate in the pathway from succinyl-CoA to heme synthesis, appreciably restored succinyl-CoA levels and OXPHOS capacity and prevented HF progression in MI mice. Previous reports also suggested the presence of succinyl-CoA metabolism abnormalities in cardiac muscles of HF patients. Our results identified that changes in succinyl-CoA usage in different metabolisms of the mitochondrial energy production system is characteristic to chronic HF, and although similar alterations are known to occur in healthy conditions, such as during strenuous exercise, they may often occur irreversibly in chronic HF leading to a decrease in succinyl-CoA. Consequently, nutritional interventions compensating the succinyl-CoA consumption are expected to be promising strategies to treat HF.

Paced QRS morphology mimicking complete left bundle branch block induced by right ventricular pacing is associated with pacing-induced cardiomyopathy.

INTRODUCTION: Right ventricular (RV) pacing sometimes causes left ventricular (LV) systolic dysfunction, also known as pacing-induced cardiomyopathy (PICM). However, the association between specifically paced QRS morphology and PICM development has not been elucidated. This study aimed to investigate the association between paced QRS mimicking a complete left bundle branch block (CLBBB) and PICM development. METHODS: We retrospectively screened 2009 patients who underwent pacemaker implantation from 2010 to 2020 in seven institutions. Patients who received pacemakers for an advanced atrioventricular block or bradycardia with atrial fibrillation, baseline LV ejection fraction (LVEF) ≥ 50%, and echocardiogram recorded at least 6 months postimplantation were included. The paced QRS recorded immediately after implantation was analyzed. A CLBBB-like paced QRS was defined as meeting the CLBBB criteria of the American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society in 2009. PICM was defined as a ≥10% LVEF decrease, resulting in an LVEF of <50%. RESULTS: Among the 270 patients analyzed, PICM was observed in 38. Baseline LVEF was lower in patients with PICM, and CLBBB-like paced QRS was frequently observed in PICM. Multivariate analysis revealed that low baseline LVEF (odds ratio [OR]: 0.93 per 1% increase, 95% confidence interval [CI]: 0.89-0.98, p = 0.006) and CLBBB-like paced QRS (OR: 2.69, 95% CI: 1.25-5.76, p = 0.011) were significantly associated with PICM development. CONCLUSION: CLBBB-like paced QRS may be a novel risk factor for PICM. RV pacing, which causes CLBBB-like QRS morphology, may need to be avoided, and patients with CLBBB-like paced QRS should be followed-up carefully.

Triglyceride-Glucose Index Associated with Future Renal Function Decline in the General Population.

BACKGROUND: The triglyceride-glucose index (TyG index), calculated as the logarithmic product of fasting triglyceride and glucose concentrations, is recognized as a simple marker of insulin resistance. However, the association between the TyG index and future decline of renal function remains unclear in the general population. OBJECTIVE: To investigate whether the TyG index was associated with future decline of renal function in the general population who had not progressed to chronic kidney disease stage G2. DESIGN: Retrospective longitudinal observational cohort study. PARTICIPANTS: Individuals who received a population-based health checkup at JA Ehime Kouseiren Checkup Center from 2010 to 2019 (n = 134,007). Individuals without data of baseline fasting triglyceride or glucose levels, or baseline and follow-up data of estimated glomerular filtration rate (eGFR), or those with baseline eGFR < 60 mL/min/1.73 m2 were excluded. MAIN MEASURES: Future renal function decline, defined as a ≥ 25% decrease in eGFR from baseline. KEY RESULTS: Of 10,758 participants, 8,076 were classified into the low TyG index group (TyG index < 8.76, 1st to 3rd quartiles) and 2,682 into the high TyG index group (TyG index ≥ 8.76, 4th quartile). The mean follow-up period was 37.8 ± 23.6 months. The incidence rates of renal function decline were 0.31 and 0.69 per 100 person-years in the low and high TyG index groups, respectively. In multivariate Cox proportional hazard models, high TyG index was significantly associated with future renal function decline (hazard ratio 2.25, 95% CI 1.40-3.60). This association was consistent across subgroups stratified by age, sex, body mass index, baseline eGFR, and diagnosed hypertension, diabetes, or dyslipidemia. CONCLUSION: In the general population, high TyG index was associated with future renal function decline. The TyG index may be useful in identifying individuals at high risk for future renal function decline in the setting of health checkups.

Overview of the 87th Annual Scientific Meeting of the Japanese Circulation Society (JCS2023)　- New Challenge With Next Generation.

The 87thAnnual Meeting of the Japanese Circulation Society (JCS2023) was held in March 2023 in Fukuoka, Japan, marking the first in-person gathering after the COVID-19 pandemic. With the theme of "New Challenge With Next Generation" the conference emphasized the development of future cardiovascular leaders and technologies such as artificial intelligence (AI). Notable sessions included the Mikamo Lecture on heart failure and the Mashimo Lecture on AI in medicine. Various hands-on sessions and participatory events were well received, promoting learning and networking. Post-event surveys showed high satisfaction among participants, with positive feedback on face-to-face interactions and the overall experience. JCS2023, attended by 17,852 participants, concluded successfully, marking a significant milestone in post-pandemic meetings, and advancing cardiovascular medicine.

Mapping of Purkinje-related ventricular arrhythmias by a multispline catheter with small and close-paired electrodes: Comparison with conventional catheters.

BACKGROUND: Precise mapping of the Purkinje fiber network is essential in catheter ablation of Purkinje-related ventricular arrhythmias (PrVAs). We sought to evaluate the mapping ability of a multi-spline duodecapolar catheter (PentaRay) for PrVAs. METHODS: Mappings of Purkinje fibers by PentaRay catheters were compared with those by conventional mapping catheters in consecutive patients undergoing catheter ablation of PrVAs from 2015 to 2022. RESULTS: Sixteen PrVAs (7 premature ventricular contractions or non-reentrant fascicular tachycardias [PVCs/NRFTs] and 9 fascicular ventricular tachycardias [FVTs]) were retrospectively studied. In PVCs/NRFTs, earliest preceding Purkinje potentials (PPs) could be recorded by the PentaRay catheters but not by the mapping and ablation catheters in 5 cases. At the earliest PP sites, the precedence from the QRS onset was greater, and the amplitude of the preceding potentials was higher in the PentaRay catheter compared with those in the mapping and ablation catheter (-62.0 ± 42.8 vs. -29.4 ± 34.2 ms, P = 0.02; 0.45 ± 0.43 vs. 0.09 ± 0.08 mV, P = 0.02). In FVTs, late diastolic potentials (P1) were recorded by the PentaRay catheters but not by the mapping and ablation catheters or the linear duodecapolar catheter in 2 cases. The amplitude of P1 was higher in the PentaRay catheter compared with that in the linear duodecapolar catheter and the mapping and ablation catheters (0.72 ± 0.49 vs. 0.17 ± 0.18 vs. 0.27 ± 0.21 mV, P = 0.0006, P = 0.002). The localized critical PPs, defined as the earliest preceding potentials in PVCs/NRFTs and P1 in FVTs, could be recorded in all the patients by the PentaRay catheter. The mapping ability of critical PPs of PrVAs was better with the PentaRay catheter than with the conventional mapping catheters (16/16 vs. 9/16, P = 0.004 by McNemar exact test). CONCLUSIONS: The PentaRay catheter has clinical advantages in mapping of the Purkinje fiber network to reveal critical PPs as ablation targets of PrVAs.

Efficacy and safety of the urate-lowering agent febuxostat in chronic heart failure patients with hyperuricemia: results from the LEAF-CHF study.

Hyperuricemia is an independent predictor of mortality in patients with chronic heart failure (CHF). To determine whether febuxostat, a urate-lowering agent, may improve clinical outcomes in CHF patients, we conducted a multicenter, prospective, randomized, open-label, blinded endpoint study with a treatment period of 24 weeks. We randomly assigned Japanese outpatients diagnosed with both CHF with reduced left ventricular ejection fraction (LVEF < 40%) and asymptomatic hyperuricemia (serum uric acid [UA] levels > 7.0 mg/dl and < 10.0 mg/dl) to either a febuxostat group (n = 51) or a control group (n = 50). The primary efficacy endpoint was the change in log-transformed plasma B-type natriuretic peptide (BNP) levels from baseline to week 24 (or at discontinuation). The secondary efficacy endpoints were the changes in LV systolic or diastolic function evaluated by echocardiography, New York Heart Association (NYHA) class, hemoglobin, and estimated glomerular filtration rate from baseline to week 24, and the change in log-transformed plasma BNP levels or serum UA levels from baseline to weeks 4, 8, 12, 16 and 20 (BNP) or weeks 4, 8, 12, 16, 20 and 24 (serum UA). The primary safety endpoints were occurrence of all-cause death or major cardiovascular events. The mean age of participants was 70 years; 14% were female. The febuxostat group and the control group did not differ with respect to the primary efficacy endpoint (p = 0.13), although the decrease in log-transformed plasma BNP levels from baseline to each of weeks 4, 8, 12, 16 and 20 was greater in the febuxostat group. There were no significant differences between the two groups in the primary safety endpoints or the secondary efficacy endpoints except reduced serum UA levels in the febuxostat group. Febuxostat did not reduce plasma BNP levels at week 24 in patients with CHF, but it appeared safe with no increase in major cardiovascular events and all-cause or cardiovascular mortality.

Hemoglobin Level Can Predict Heart Failure Hospitalization in Patients with Advanced Heart Failure Awaiting Heart Transplantation without Inotropes or Mechanical Circulatory Support.

Although anemia is a common comorbidity that often coexists with heart failure (HF), its clinical impact in patients with advanced HF remains unclear. We investigated the impact of hemoglobin levels on clinical outcomes in patients with advanced HF listed for heart transplantation without intravenous inotropes or mechanical circulatory support.We retrospectively reviewed the clinical data of patients listed for heart transplantation at our institute who did not receive intravenous inotropes or mechanical circulatory support between 2011 and 2022. We divided the patients into those with hemoglobin levels lower or higher than the median value and compared the composite of all-cause death and HF hospitalization within 1 year from the listing date.We enrolled consecutive 38 HF patients (27 males, 49.1 ± 10.8 years old). The median hemoglobin value at the time of listing for heart transplantation was 12.9 g/dL, and 66.7% of the patients had iron deficiency. None of the patients in either group died within 1 year. The HF hospitalization-free survival rate was significantly lower in the lower hemoglobin group (40.9% versus 81.9% at 1 year, P = 0.020). Multivariate Cox proportional hazards model analysis showed that hemoglobin as a continuous variable was an independent predictor for HF hospitalization (odds ratio 0.70, 95% confidence interval 0.49-0.97, P = 0.030).Hemoglobin level at the time of listing for heart transplantation was a predictor of hospitalization in heart-transplant candidates without intravenous inotropes or mechanical circulatory support.

Different Impact of Immunosuppressive Therapy on Cardiac Outcomes in Systemic Versus Isolated Cardiac Sarcoidosis.

Isolated cardiac sarcoidosis (iCS) is increasingly recognized; however, its prognosis and the efficacy of immunosuppressive therapy remain undetermined. We aimed to compare the prognosis of iCS and systemic sarcoidosis including cardiac involvement (sCS) under immunosuppressive therapy.We retrospectively reviewed the clinical data of 42 patients with sCS and 30 patients with iCS diagnosed at Kyushu University Hospital from 2004 through 2022. We compared the characteristics and the rate of adverse cardiac events including cardiac death, fatal ventricular tachyarrhythmia, and heart failure hospitalization between the 2 groups. The median follow-up time was 1535 [interquartile range, 630-2555] days, without a significant difference between the groups. There were no significant differences in gender, NYHA class, or left ventricular ejection fraction. Immunosuppressive agents were administered in 86% of sCS and in 73% of iCS patients (P = 0.191). When analyzed only with patients receiving immunosuppressive therapy (sCS, n = 36; iCS, n = 21), the cardiac event-free survival was significantly lower in iCS than sCS (37% versus 79%, P = 0.002). Myocardial LGE content at the initial diagnosis was comparable in both groups. The disease activity was serially evaluated in 26 sCS and 16 iCS patients by quantitative measures of FDG-PET including cardiac metabolic volume and total lesion glycolysis, representing 3-dimensional distribution and intensity of inflammation in the entire heart. Although iCS patients had lower baseline disease activity than sCS patients, immunosuppressive therapy did not attenuate disease activity in iCS in contrast to sCS.iCS showed a poorer response to immunosuppressive therapy and a worse cardiac prognosis compared to sCS despite lower baseline disease activity.

Nationwide Temporal Trends in Clinical Characteristics and Treatment of Dilated Cardiomyopathy From 2003 to 2013 in Japan　- A Report From Clinical Personal Records.

BACKGROUND: Little is known about nationwide temporal trends in the clinical characteristics and treatment of dilated cardiomyopathy (DCM) in Japan.Methods and Results: We collected data regarding demographics, echocardiography, and treatment of DCM between 2003 to 2013 from Clinical Personal Records, a national registry organized by the Japanese Ministry of Health, Labour, and Welfare. Among the 40,794 DCM patients screened, 27,702 with left ventricular ejection fraction (LVEF) <50% and age ≥18 years were enrolled in this study and divided into 3 groups according to registration year: Group 1, 2003-2005 (10,006 patients); Group 2, 2006-2010 (11,252 patients); and Group 3, 2011-2013 (6,444 patients). Over time, there were decreases in age at registration (mean [±SD] 58.6±13.0 vs. 56.8±13.8 vs. 56.2±13.8 years; P<0.001) and LVEF (33.5±10.0% vs. 31.1±9.9% vs. 29.2± 9.7%; P<0.001), and an increase in patients with New York Heart Association Class III-IV (28.2% vs. 35.2% vs. 41.0%; P<0.001). The use of ß-blockers (59.1% vs. 79.3% vs. 87.8%; P<0.001) and mineralocorticoid receptor antagonists (30.6% vs. 35.8% vs. 39.7%; P<0.001) increased over time. In multivariate analysis, male sex, systolic blood pressure, chronic kidney disease, hemoglobin, and registration year were positively associated, whereas age and LVEF were negatively associated, with ß-blocker prescription. CONCLUSIONS: Although the clinical characteristics of DCM changed, the implementation of optimal medical therapy for DCM increased from 2003 to 2013 in Japan.

Treatments for skeletal muscle abnormalities in heart failure: sodium-glucose transporter 2 and ketone bodies.

Various skeletal muscle abnormalities are known to occur in heart failure (HF) and are closely associated with exercise intolerance. Particularly, abnormal energy metabolism caused by mitochondrial dysfunction in skeletal muscle is a cause of decreased endurance exercise capacity. However, to date, no specific drug treatment has been established for the skeletal muscle abnormalities and exercise intolerance occurring in patients with HF. Sodium-glucose transporter 2 (SGLT2) inhibitors promote glucose excretion by suppressing glucose reabsorption in the renal tubules, which has a hypoglycemic effect independent of insulin secretion. Recently, large clinical trials have demonstrated that treatment with SGLT2 inhibitors suppresses cardiovascular events in patients who have HF with systolic dysfunction. Mechanisms of the therapeutic effects of SGLT2 inhibitors for HF have been suggested to be diuretic, suppression of neurohumoral factor activation, renal protection, and improvement of myocardial metabolism, but this has not been clarified to date. SGLT2 inhibitors are known to increase blood ketone bodies. This suggests that they may improve the abnormal skeletal muscle metabolism in HF, that is, improve fatty acid metabolism, suppress glycolysis, and use ketone bodies in mitochondrial energy production. Ultimately, they may improve aerobic metabolism in skeletal muscle, suppress anaerobic metabolism, and improve aerobic exercise capacity at the level of the anaerobic threshold. The potential actions of such SGLT2 inhibitors explain their effectiveness in HF and may be candidates for new drug treatments aimed at improving exercise intolerance. In this review, we outlined the effects of SGLT2 inhibitors on skeletal muscle metabolism, with a particular focus on ketone metabolism.

Angiotensin-converting enzyme inhibitor prevents skeletal muscle fibrosis in diabetic mice.

NEW FINDINGS: What is the central question of this study? We questioned whether an angiotensin-converting enzyme (ACE) inhibitor prevents skeletal muscle fibrosis in diabetic mice. What is the main finding and its importance? Administration of ACE inhibitor prevents the increase in skeletal muscle fibrosis during the early phase after induction of diabetes by streptozotocin. Our findings might provide a new therapeutic target for skeletal muscle abnormalities in diabetes. ABSTRACT: Fibrosis is characterized by the excessive production and accumulation of extracellular matrix components, including collagen. Although the extracellular matrix is an essential component of skeletal muscle, fibrosis can have negative effects on muscle function. Skeletal muscle fibrosis was shown to be increased in spontaneously hypertensive rats and to be prevented by an angiotensin-converting enzyme (ACE) inhibitor, an antihypertensive drug, in dystrophic mice or a mouse model of myocardial infarction. In this study, we therefore analysed whether (1) there is increased skeletal muscle fibrosis in streptozotocin (STZ)-induced diabetic mice, and (2) a preventive effect on skeletal muscle fibrosis by administration of an ACE inhibitor. Skeletal muscle fibrosis was significantly increased in STZ-induced diabetic mice compared with control mice from 2 to 14 days post-STZ. The ACE inhibitor prevented both skeletal muscle fibrosis and the reduction in muscle function in STZ-treated mice. Our study demonstrated that administration of an ACE inhibitor prevents the increase in skeletal muscle fibrosis during the early phase after onset of diabetes. Our findings might provide a new therapeutic target for skeletal muscle abnormalities in diabetes. Future studies are required to clarify whether skeletal muscle fibrosis is also linked directly to physical activity.

Enhanced Echo Intensity of Skeletal Muscle Is Associated With Exercise Intolerance in Patients With Heart Failure.

BACKGROUND: Skeletal muscle is quantitatively and qualitatively impaired in patients with heart failure (HF), which is closely linked to lowered exercise capacity. Ultrasonography (US) for skeletal muscle has emerged as a useful, noninvasive tool to evaluate muscle quality and quantity. Here we investigated whether muscle quality based on US-derived echo intensity (EI) is associated with exercise capacity in patients with HF. METHODS AND RESULTS: Fifty-eight patients with HF (61 ± 12 years) and 28 control subjects (58 ± 14 years) were studied. The quadriceps femoris echo intensity (QEI) was significantly higher and the quadriceps femoris muscle thickness (QMT) was significantly lower in the patients with HF than the controls (88.3 ± 13.4 vs 81.1 ± 7.5, P= .010; 5.21 ± 1.10 vs 6.54 ±1.34 cm, P< .001, respectively). By univariate analysis, QEI was significantly correlated with age, peak oxygen uptake (VO2), and New York Heart Association class in the HF group. A multivariable analysis revealed that the QEI was independently associated with peak VO2 after adjustment for age, gender, body mass index, and QMT: ß-coefficient = -11.80, 95%CI (-20.73, -2.86), P= .011. CONCLUSION: Enhanced EI in skeletal muscle was independently associated with lowered exercise capacity in HF. The measurement of EI is low-cost, easily accessible, and suitable for assessment of HF-related alterations in skeletal muscle quality.

Type 2 diabetes is an independent predictor of lowered peak aerobic capacity in heart failure patients with non-reduced or reduced left ventricular ejection fraction.

BACKGROUND: Although type 2 diabetes mellitus (T2DM) is one of the most frequent comorbidities in patients with chronic heart failure (CHF), the effects of T2DM on the exercise capacity of CHF patients are fully unknown. Here, we tested the hypothesis that the coexistence of T2DM lowers CHF patients' peak aerobic capacity. METHODS: We retrospectively analyzed the cases of 275 Japanese CHF patients with non-reduced ejection fraction (left ventricular ejection fraction [LVEF] ≥ 40%) or reduced EF (LVEF < 40%) who underwent cardiopulmonary exercise testing. We divided them into diabetic and nondiabetic groups in each CHF cohort. RESULTS: The mean peak oxygen uptake (VO2) value was 16.87 mL/kg/min in the non-reduced LVEF cohort and 15.52 mL/kg/min in the reduced LVEF cohort. The peak VO2 was lower in the diabetics versus the nondiabetics in the non-reduced LVEF cohort with the mean difference (95% confidence interval [95% CI]) of - 0.93 (- 1.82 to - 0.04) mL/kg/min and in the reduced LVEF cohort with the mean difference of - 1.05 (- 1.96 to - 0.15) mL/kg/min, after adjustment for age-squared, gender, anemia, renal function, LVEF, and log B-type natriuretic peptide (BNP). The adjusted VO2 at anaerobic threshold (AT), a submaximal aerobic capacity, was also decreased in the diabetic patients with both non-reduced and reduced LVEFs. Intriguingly, the diabetic patients had a lower adjusted peak O2 pulse than the nondiabetic patients in the reduced LVEF cohort, but not in the non-reduced LVEF cohort. A multivariate analysis showed that the presence of T2DM was an independent predictor of lowered peak VO2 in CHF patients with non-reduced LVEF and those with reduced LVEF. CONCLUSIONS: T2DM was associated with lowered peak VO2 in CHF patients with non-reduced or reduced LVEF. The presence of T2DM has a negative impact on CHF patients' exercise capacity, and the degree of impact is partly dependent on their LV systolic function.

The disruption of invariant natural killer T cells exacerbates cardiac hypertrophy and failure caused by pressure overload in mice.

NEW FINDINGS: What is the central question of this study? We questioned whether the disruption of invariant natural killer T (iNKT) cells exacerbates left ventricular (LV) remodelling and heart failure after transverse aortic constriction in mice. What are the main findings and their importance? Pressure overload induced by transverse aortic constriction increased the infiltration of iNKT cells in mouse hearts. The disruption of iNKT cells exacerbated LV remodelling and hastened the transition from hypertrophy to heart failure, in association with the activation of mitogen-activated protein kinase signalling. Activation of iNKT cells modulated the immunological balance in this process and played a protective role against LV remodelling and failure. ABSTRACT: Chronic inflammation is involved in the development of cardiac remodelling and heart failure (HF). Invariant natural killer T (iNKT) cells, a subset of T lymphocytes, have been shown to produce various cytokines and orchestrate tissue inflammation. The pathophysiological role of iNKT cells in HF caused by pressure overload has not been studied. In the present study, we investigated whether the disruption of iNKT cells affected this process in mice. Transverse aortic constriction (TAC) and a sham operation were performed in male C57BL/6J wild-type (WT) and iNKT cell-deficient Jα18 knockout (KO) mice. The infiltration of iNKT cells was increased after TAC. The disruption of iNKT cells exacerbated left ventricular (LV) remodelling and hastened the transition to HF after TAC. Histological examinations also revealed that the disruption of iNKT cells induced greater myocyte hypertrophy and a greater increase in interstitial fibrosis after TAC. The expressions of interleukin-10 and tumour necrosis factor-α mRNA and their ratio in the LV after TAC were decreased in the KO compared with WT mice, which might indicate that the disruption of iNKT cells leads to an imbalance between T-helper type 1 and type 2 cytokines. The phosphorylation of extracellular signal-regulated kinase was significantly increased in the KO mice. The disruption of iNKT cells exacerbated the development of cardiac remodelling and HF after TAC. The activation of iNKT cells might play a protective role against HF caused by pressure overload. Targeting the activation of iNKT cells might thus be a promising candidate as a new therapeutic strategy for HF.

Serum Brain-Derived Neurotrophic Factor Levels Are Associated with Skeletal Muscle Function but Not with Muscle Mass in Patients with Heart Failure.

Heart failure (HF) is associated with aberrant skeletal muscle impairments, which are closely linked to the severity of HF. A low level of brain-derived neurotrophic factor (BDNF), a myokine produced in the skeletal muscle, is known to be involved in reduced exercise capacity and poor prognosis in HF. However, little is known about the factors or conditions of skeletal muscle associated with BDNF levels. We investigated the association between serum BDNF levels and the skeletal muscle mass and function in HF patients (n = 60, 63 ± 13 years) and age-matched controls (n = 29, 61 ± 16 years). The serum BDNF level was significantly lower in the HF patients compared to the controls (24.9 ± 0.9 versus 28.6 ± 1.3, P = 0.021). In a univariate analysis, BDNF was significantly correlated with the peak oxygen uptake, estimated glomerular filtration rate, 10-m gait speed, and muscle strength, but not with the body mass index or lean mass in the HF group. A multiple linear regression analysis revealed that BDNF was independently associated with muscle strength (ß-coefficient = 2.80, 95%CI: 1.89-11.8, P = 0.008). Serum BDNF levels were associated with exercise capacity and skeletal muscle function, but not with muscle mass. These novel findings may suggest that BDNF production is controlled by muscle function and activity and consequently regulates exercise capacity, highlighting the importance of adequate training regarding skeletal muscle in HF patients.

Linoleic acid improves assembly of the CII subunit and CIII2/CIV complex of the mitochondrial oxidative phosphorylation system in heart failure.

BACKGROUND: Linoleic acid is the major fatty acid moiety of cardiolipin, which is central to the assembly of components involved in mitochondrial oxidative phosphorylation (OXPHOS). Although linoleic acid is an essential nutrient, its excess intake is harmful to health. On the other hand, linoleic acid has been shown to prevent the reduction in cardiolipin content and to improve mitochondrial function in aged rats with spontaneous hypertensive heart failure (HF). In this study, we found that lower dietary intake of linoleic acid in HF patients statistically correlates with greater severity of HF, and we investigated the mechanisms therein involved. METHODS: HF patients, who were classified as New York Heart Association (NYHA) functional class I (n = 45), II (n = 93), and III (n = 15), were analyzed regarding their dietary intakes of different fatty acids during the one month prior to the study. Then, using a mouse model of HF, we confirmed reduced cardiolipin levels in their cardiac myocytes, and then analyzed the mechanisms by which dietary supplementation of linoleic acid improves cardiac malfunction of mitochondria. RESULTS: The dietary intake of linoleic acid was significantly lower in NYHA III patients, as compared to NYHA II patients. In HF model mice, both CI-based and CII-based OXPHOS activities were affected together with reduced cardiolipin levels. Silencing of CRLS1, which encodes cardiolipin synthetase, in cultured cardiomyocytes phenocopied these events. Feeding HF mice with linoleic acid improved both CI-based and CII-based respiration as well as left ventricular function, together with an increase in cardiolipin levels. However, although assembly of the respirasome (i.e., CI/CIII2/CIV complex), as well as assembly of CII subunits and the CIII2/CIV complex statistically correlated with cardiolipin levels in cultured cardiomyocytes, respirasome assembly was not notably restored by dietary linoleic acid in HF mice. Therefore, although linoleic acid may significantly improve both CI-based and CII-based respiration of cardiomyocytes, respirasomes impaired by HF were not easily repaired by the dietary intake of linoleic acid. CONCLUSIONS: Dietary supplement of linoleic acid is beneficial for improving cardiac malfunction in HF, but is unable to completely cure HF.

Tolerability, Efficacy, and Safety of Bisoprolol vs. Carvedilol in Japanese Patients With Heart Failure and Reduced Ejection Fraction　- The CIBIS-J Trial.

BACKGROUND: The comparative tolerability, efficacy, and safety of bisoprolol and carvedilol have not been established in Japanese patients with heart failure and reduced ejection fraction (HFrEF). Methods and Results: The CIBIS-J trial is a multicenter, open-label, non-inferiority randomized controlled trial of bisoprolol vs. carvedilol in 217 patients with HFrEF (EF ≤40%). The primary endpoint was tolerability, defined as reaching and maintaining the maximum maintenance dose (bisoprolol 5 mg/day or carvedilol 20 mg/day) during 48 weeks of treatment. The primary endpoint was achieved in 41.4% of patients in bisoprolol (n=111) and 42.5% in carvedilol (n=106) groups. The non-inferiority of tolerability of bisoprolol compared with carvedilol was not supported, however, neither ß-blocker was superior with regard to tolerability. Heart rate (HR) decreased in both groups and its decrease from baseline was significantly greater in the bisoprolol group (20.3 vs. 15.4 beats/min at 24 week, P<0.05). Plasma B-type natriuretic peptide (BNP) levels decreased in both groups and the decrease was significantly greater in the carvedilol group (12.4 vs. 39.0 % at 24 weeks, P<0.05). CONCLUSIONS: There were no significant differences between bisoprolol and carvedilol in the tolerability of target doses in Japanese HFrEF patients. The clinical efficacy and safety were also similar despite the greater reduction in HR by bisoprolol and plasma BNP by carvedilol.

Impact of High Respiratory Exchange Ratio During Submaximal Exercise on Adverse Clinical Outcome in Heart Failure.

BACKGROUND: Oxygen uptake (V̇O2) at peak workload and anaerobic threshold (AT) workload are often used for grading heart failure (HF) severity and predicting all-cause mortality. The clinical relevance of respiratory exchange ratio (RER) during exercise, however, is unknown. Methods and Results: We retrospectively studied 295 HF patients (57±15 years, NYHA class I-III) who underwent cardiopulmonary exercise testing. RER was measured at rest; at AT workload; and at peak workload. Peak V̇O2 had an inverse correlation with RER at AT workload (r=-0.256), but not at rest (r=-0.084) or at peak workload (r=0.090). Using median RER at AT workload, we divided the patients into high RER (≥0.97) and low RER (<0.97) groups. Patients with high RER at AT workload were characterized by older age, lower body mass index, anemia, and advanced NYHA class. After propensity score matching, peak V̇O2 tended to be lower in the high-RER than in the low-RER group (14.9±4.5 vs. 16.1±5.0 mL/kg/min, P=0.06). On Kaplan-Meier analysis, HF patients with a high RER at AT workload had significantly worse clinical outcomes, including all-cause mortality and rate of readmission due to HF worsening over 3 years (29% vs. 15%, P=0.01). CONCLUSIONS: High RER during submaximal exercise, particularly at AT workload, is associated with poor clinical outcome in HF patients.