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.

Serine biosynthesis as a novel therapeutic target for dilated cardiomyopathy.

AIMS: Genetic dilated cardiomyopathy (DCM) is a leading cause of heart failure. Despite significant progress in understanding the genetic aetiologies of DCM, the molecular mechanisms underlying the pathogenesis of familial DCM remain unknown, translating to a lack of disease-specific therapies. The discovery of novel targets for the treatment of DCM was sought using phenotypic sceening assays in induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) that recapitulate the disease phenotypes in vitro. METHODS AND RESULTS: Using patient-specific iPSCs carrying a pathogenic TNNT2 gene mutation (p.R183W) and CRISPR-based genome editing, a faithful DCM model in vitro was developed. An unbiased phenotypic screening in TNNT2 mutant iPSC-derived cardiomyocytes (iPSC-CMs) with small molecule kinase inhibitors (SMKIs) was performed to identify novel therapeutic targets. Two SMKIs, Gö 6976 and SB 203580, were discovered whose combinatorial treatment rescued contractile dysfunction in DCM iPSC-CMs carrying gene mutations of various ontologies (TNNT2, TTN, LMNA, PLN, TPM1, LAMA2). The combinatorial SMKI treatment upregulated the expression of genes that encode serine, glycine, and one-carbon metabolism enzymes and significantly increased the intracellular levels of glucose-derived serine and glycine in DCM iPSC-CMs. Furthermore, the treatment rescued the mitochondrial respiration defects and increased the levels of the tricarboxylic acid cycle metabolites and ATP in DCM iPSC-CMs. Finally, the rescue of the DCM phenotypes was mediated by the activating transcription factor 4 (ATF4) and its downstream effector genes, phosphoglycerate dehydrogenase (PHGDH), which encodes a critical enzyme of the serine biosynthesis pathway, and Tribbles 3 (TRIB3), a pseudokinase with pleiotropic cellular functions. CONCLUSIONS: A phenotypic screening platform using DCM iPSC-CMs was established for therapeutic target discovery. A combination of SMKIs ameliorated contractile and metabolic dysfunction in DCM iPSC-CMs mediated via the ATF4-dependent serine biosynthesis pathway. Together, these findings suggest that modulation of serine biosynthesis signalling may represent a novel genotype-agnostic therapeutic strategy for genetic DCM.

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.

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.

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.

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.

The novel heart-specific RING finger protein 207 is involved in energy metabolism in cardiomyocytes.

A failing heart shows severe energy insufficiency, and it is presumed that this energy shortage plays a critical role in the development of cardiac dysfunction. However, little is known about the mechanisms that cause energy metabolic alterations in the failing heart. Here, we show that the novel RING-finger protein 207 (RNF207), which is specifically expressed in the heart, plays a role in cardiac energy metabolism. Depletion of RNF207 in neonatal rat cardiomyocytes (NRCs) leads to a reduced cellular concentration of adenosine triphosphate (ATP) and mitochondrial dysfunction. Consistent with this result, we observed here that the expression of RNF207 was significantly reduced in mice with common cardiac diseases including heart failure. Intriguingly, proteomic approaches revealed that RNF207 interacts with the voltage-dependent anion channel (VDAC), which is considered to be a key regulator of mitochondria function, as an RNF207-interacting protein. Our findings indicate that RNF207 is involved in ATP production by cardiomyocytes, suggesting that RNF207 plays an important role in the development of heart failure.

Serum brain-derived neurotropic factor level predicts adverse clinical outcomes in patients with heart failure.

BACKGROUND: Brain-derived neurotropic factor (BDNF) is involved in cardiovascular diseases as well as skeletal muscle energy metabolism and depression. We investigated whether serum BDNF level was associated with prognosis in patients with heart failure (HF). METHODS AND RESULTS: We measured the serum BDNF level in 58 patients with HF (59.2 ± 13.7 years old, New York Heart Association functional class I-III) at baseline, and adverse events, including all cardiac deaths and HF rehospitalizations, were recorded during the median follow-up of 20.3 months. In a univariate analysis, serum BDNF levels were significantly associated with peak oxygen capacity (ß = 0.547; P = .003), anaerobic threshold (ß = 0.929; P = .004), and log minute ventilation/carbon dioxide production slope (ß = -10.15; P = .005), but not Patient Health Questionnaire scores (ß = -0.099; P = .586). A multivariate analysis demonstrated that serum BDNF level was an independent prognostic factor of adverse events (hazard ratio 0.41, 95% confidence interval 0.20-0.84; P = .003). The receiver operating characteristic curve demonstrated that low levels of BDNF (<17.4 ng/mL) were associated with higher rates of adverse events compared with high levels of BDNF (≥17.4 ng/mL; log rank test: P < .001). CONCLUSIONS: Decreased serum BDNF levels were significantly associated with adverse outcomes in HF patients, suggesting that these levels can be a useful prognostic biomarker.

Sesamin prevents decline in exercise capacity and impairment of skeletal muscle mitochondrial function in mice with high-fat diet-induced diabetes.

NEW FINDINGS: What is the central question of this study? Our aim was to examine whether sesamin can prevent a decline in exercise capacity in high-fat diet-induced diabetic mice. Our hypothesis was that maintenance of mitochondrial function and attenuation of oxidative stress in the skeletal muscle would contribute to this result. What is the main finding and its importance? The new findings are that sesamin prevents the diabetes-induced decrease in exercise capacity and impairment of mitochondrial function through the inhibition of NAD(P)H oxidase-dependent oxidative stress in the skeletal muscle. Sesamin may be useful as a novel agent for the treatment of diabetes mellitus. ABSTRACT: We previously reported that exercise capacity and skeletal muscle mitochondrial function in diabetic mice were impaired, in association with the activation of NAD(P)H oxidase. It has been reported that sesamin inhibits NAD(P)H oxidase-induced superoxide production. Therefore, we examined whether the antioxidant sesamin could prevent a decline in exercise capacity in mice with high-fat diet (HFD)-induced diabetes. C57BL/6J mice were fed a normal diet (ND) or HFD, then treated or not with sesamin (0.2%) to yield the following four groups: ND, ND+Sesamin, HFD and HFD+Sesamin (n = 10 each). After 8 weeks, body weight, fat weight, blood glucose, insulin, triglyceride, total cholesterol and fatty acid were significantly increased in HFD compared with ND mice. Sesamin prevented the increases in blood insulin and lipid levels in HFD-fed mice, but did not affect the plasma glucose. Exercise capacity determined by treadmill tests was significantly reduced in HFD mice, but almost completely recovered in HFD+Sesamin mice. Citrate synthase activity was significantly decreased in the skeletal muscle of HFD mice, and these decreases were also inhibited by sesamin. Superoxide anion and NAD(P)H oxidase activity were significantly increased in HFD mice compared with the ND mice and were ameliorated by sesamin. Sesamin prevented the decline in exercise capacity in HFD-induced diabetic mice via maintenance of mitochondrial function, fat oxidation and attenuation of oxidative stress in the skeletal muscle. Our data suggest that sesamin may be useful as a novel agent for the treatment of diabetes mellitus.

Angiotensin II can directly induce mitochondrial dysfunction, decrease oxidative fibre number and induce atrophy in mouse hindlimb skeletal muscle.

NEW FINDINGS: What is the central question of this study? Does angiotensin II directly induce skeletal muscle abnormalities? What is the main finding and its importance? Angiotensin II induces skeletal muscle abnormalities and reduced exercise capacity. Mitochondrial dysfunction and a decreased number of oxidative fibres are manifest early, while muscle atrophy is seen later. Thus, angiotensin II may play an important role in the skeletal muscle abnormalities observed in a wide variety of diseases. Skeletal muscle abnormalities, such as mitochondrial dysfunction, a decreased percentage of oxidative fibres and atrophy, are the main cause of reduced exercise capacity observed in ageing and various diseases, including heart failure. The renin-angiotensin system, particularly angiotensin II (Ang II), is activated in the skeletal muscle in these conditions. Here, we examined whether Ang II could directly induce these skeletal muscle abnormalities and investigated their time course. Angiotensin II (1000 ng kg(-1)  min(-1) ) or vehicle was administered to male C57BL/6J mice (10-12 weeks of age) via subcutaneously implanted osmotic minipumps for 1 or 4 weeks. Angiotensin II significantly decreased body and hindlimb skeletal muscle weights compared with vehicle at 4 weeks. In parallel, muscle cross-sectional area was also decreased in the skeletal muscle at 4 weeks. Muscle RING finger-1 and atrogin-1 were significantly increased in the skeletal muscle from mice treated with Ang II. In addition, cleaved caspase-3 and terminal deoxynucleotidyl trasferase-mediated dUTP nick-positive nuclei were significantly increased in mice treated with Ang II at 1 and 4 weeks, respectively. Mitochondrial oxidative enzymes, such as citrate synthase, complex I and complex III activities were significantly decreased in the skeletal muscle from mice treated Ang II at 1 and 4 weeks. NAD(P)H oxidase-derived superoxide production was increased. NADH staining revealed that type I fibres were decreased and type IIb fibres increased in mice treated with Ang II at 1 week. The work and running distance evaluated by a treadmill test were significantly decreased in mice treated with Ang II at 4 weeks. Thus, Ang II could directly induce the abnormalities in skeletal muscle function and structure.

AST-120 ameliorates lowered exercise capacity and mitochondrial biogenesis in the skeletal muscle from mice with chronic kidney disease via reducing oxidative stress.

BACKGROUND: Exercise capacity and quality of life are markedly impaired in chronic kidney disease (CKD). Increased plasma uremic toxins such as indoxyl sulfate (IS), which induce oxidative stress, may be involved in this process. An oral adsorbent, AST-120, can reduce circulating IS, however, its effects on skeletal muscle and exercise capacity have not been investigated in CKD. METHODS: Subtotal-nephrectomy or sham operation was performed in 8-week-old C57BL/6J mice. They were divided into two groups with or without 8% (w/w) of AST-120 in standard diet for 20 weeks. Sham, Sham + AST-120, CKD and CKD + AST-120 (n = 12, each group) were studied. We also conducted a C2C12 cell culture study to determine the direct effects of IS on oxidative stress. RESULTS: Plasma IS levels were significantly increased in CKD compared with Sham (1.05 ± 0.11 versus 0.21 ± 0.03 mg/dL, P <0.05), which was significantly ameliorated in CKD + AST-120 (0.41 ± 0.06 mg/dL). The running distance to exhaustion determined by treadmill tests was significantly reduced in CKD compared with Sham (267 ± 17 versus 427 ± 36 m, P <0.05), and this reduction was also significantly ameliorated in CKD + AST-120 (407 ± 38 m) without altering skeletal muscle weight. Citrate synthase activity and mitochondrial biogenesis gene were downregulated, and superoxide production was significantly increased in the skeletal muscle from CKD, and these changes were normalized in CKD + AST-120. Incubation of C2C12 cells with IS significantly increased NAD(P)H oxidase activity. CONCLUSIONS: The administration of AST-120 improved exercise capacity and mitochondrial biogenesis of skeletal muscle via reducing oxidative stress. AST-120 may be a novel therapeutic agent against exercise intolerance in CKD.

(Pro)renin receptor in skeletal muscle is involved in the development of insulin resistance associated with postinfarct heart failure in mice.

We previously reported that insulin resistance was induced by the impairment of insulin signaling in the skeletal muscle from heart failure (HF) via NAD(P)H oxidase-dependent oxidative stress. (Pro)renin receptor [(P)RR] is involved in the activation of local renin-angiotensin system and subsequent oxidative stress. We thus examined whether (P)RR inhibitor, handle region peptide (HRP), could ameliorate insulin resistance in HF after myocardial infarction (MI) by improving oxidative stress and insulin signaling in the skeletal muscle. C57BL6J mice were divided into four groups: sham operated (Sham, n = 10), Sham treated with HRP (Sham+HRP, 0.1 mg·kg(-1)·day(-1), n = 10), MI operated (MI, n = 10), and MI treated with HRP (MI+HRP, 0.1 mg/kg/day, n = 10). After 4 wk, MI mice showed left ventricular dysfunction, which was not affected by HRP. (P)RR was upregulated in the skeletal muscle after MI (149% of sham, P < 0.05). The decrease in plasma glucose after insulin load was smaller in MI than in Sham (21 ± 2 vs. 44 ± 3%, P < 0.05), and was greater in MI+HRP (38 ± 2%, P < 0.05) than in MI. Insulin-stimulated serine phosphorylation of Akt and glucose transporter 4 translocation were decreased in the skeletal muscle from MI by 48 and 49% of Sham, both of which were ameliorated in MI+HRP. Superoxide production and NAD(P)H oxidase activities were increased in MI, which was inhibited in MI+HRP. HRP ameliorated insulin resistance associated with HF by improving insulin signaling via the inhibition of NAD(P)H oxidase-induced superoxide production in the skeletal muscle. The (P)RR pathway is involved in the development of insulin resistance, at least in part, via the impairment of insulin signaling in the skeletal muscle from HF.

SGLT2 inhibition eliminates senescent cells and alleviates pathological aging.

It has been reported that accumulation of senescent cells in various tissues contributes to pathological aging and that elimination of senescent cells (senolysis) improves age-associated pathologies. Here, we demonstrate that inhibition of sodium-glucose co-transporter 2 (SGLT2) enhances clearance of senescent cells, thereby ameliorating age-associated phenotypic changes. In a mouse model of dietary obesity, short-term treatment with the SGLT2 inhibitor canagliflozin reduced the senescence load in visceral adipose tissue and improved adipose tissue inflammation and metabolic dysfunction, but normalization of plasma glucose by insulin treatment had no effect on senescent cells. Canagliflozin extended the lifespan of mice with premature aging even when treatment was started in middle age. Metabolomic analyses revealed that short-term treatment with canagliflozin upregulated 5-aminoimidazole-4-carboxamide-1-ß-D-ribofuranoside, enhancing immune-mediated clearance of senescent cells by downregulating expression of programmed cell death-ligand 1. These findings suggest that inhibition of SGLT2 has an indirect senolytic effect by enhancing endogenous immunosurveillance of senescent cells.

Personalized transcriptome signatures in a cardiomyopathy stem cell biobank.

BACKGROUND: There is growing evidence that pathogenic mutations do not fully explain hypertrophic (HCM) or dilated (DCM) cardiomyopathy phenotypes. We hypothesized that if a patient's genetic background was influencing cardiomyopathy this should be detectable as signatures in gene expression. We built a cardiomyopathy biobank resource for interrogating personalized genotype phenotype relationships in human cell lines. METHODS: We recruited 308 diseased and control patients for our cardiomyopathy stem cell biobank. We successfully reprogrammed PBMCs (peripheral blood mononuclear cells) into induced pluripotent stem cells (iPSCs) for 300 donors. These iPSCs underwent whole genome sequencing and were differentiated into cardiomyocytes for RNA-seq. In addition to annotating pathogenic variants, mutation burden in a panel of cardiomyopathy genes was assessed for correlation with echocardiogram measurements. Line-specific co-expression networks were inferred to evaluate transcriptomic subtypes. Drug treatment targeted the sarcomere, either by activation with omecamtiv mecarbil or inhibition with mavacamten, to alter contractility. RESULTS: We generated an iPSC biobank from 300 donors, which included 101 individuals with HCM and 88 with DCM. Whole genome sequencing of 299 iPSC lines identified 78 unique pathogenic or likely pathogenic mutations in the diseased lines. Notably, only DCM lines lacking a known pathogenic or likely pathogenic mutation replicated a finding in the literature for greater nonsynonymous SNV mutation burden in 102 cardiomyopathy genes to correlate with lower left ventricular ejection fraction in DCM. We analyzed RNA-sequencing data from iPSC-derived cardiomyocytes for 102 donors. Inferred personalized co-expression networks revealed two transcriptional subtypes of HCM. The first subtype exhibited concerted activation of the co-expression network, with the degree of activation reflective of the disease severity of the donor. In contrast, the second HCM subtype and the entire DCM cohort exhibited partial activation of the respective disease network, with the strength of specific gene by gene relationships dependent on the iPSC-derived cardiomyocyte line. ADCY5 was the largest hubnode in both the HCM and DCM networks and partially corrected in response to drug treatment. CONCLUSIONS: We have a established a stem cell biobank for studying cardiomyopathy. Our analysis supports the hypothesis the genetic background influences pathologic gene expression programs and support a role for ADCY5 in cardiomyopathy.

Activation of invariant natural killer T cells by α-galactosylceramide ameliorates myocardial ischemia/reperfusion injury in mice.

Invariant natural killer T (iNKT) cells orchestrate tissue inflammation via regulating various cytokine productions. However the role of iNKT cells has not been determined in myocardial ischemia/reperfusion (I/R) injury. The purpose of this study was to examine whether the activation of iNKT cells by α-galactosylceramide (α-GC), which specifically activates iNKT cells, could affect myocardial I/R injury. I/R or sham operation was performed in male C57BL/6J mice. I/R mice received the injection of either αGC (I/R+αGC, n=48) or vehicle (I/R+vehicle, n=49) 30 min before reperfusion. After 24h, infarct size/area at risk was smaller in I/R+αGC than in I/R+vehicle (37.8 ± 2.7% vs. 47.1 ± 2.5%, P<0.05), with no significant changes in area at risk. The numbers of infiltrating myeloperoxidase- and CD3-positive cells were lower in I/R+αGC. Apoptosis evaluated by TUNEL staining and caspase-3 protein was also attenuated in I/R+αGC. Myocardial gene expression of tumor necrosis factor-α and interleukin (IL)-1ß in I/R+αGC was lower to 46% and 80% of that in I/R+vehicle, respectively, whereas IL-10, IL-4, and interferon (IFN)-γ were higher in I/R+αGC than I/R+vehicle by 2.0, 4.1, and 9.6 folds, respectively. The administration of anti-IL-10 receptor antibody into I/R+αGC abolished the protective effects of αGC on I/R injury (infarct size/area at risk: 53.1 ± 5.2% vs. 37.4 ± 3.5%, P<0.05). In contrast, anti-IL-4 and anti-IFN-γ antibodies did not exert such effects. In conclusion, activated iNKT cells by αGC play a protective role against myocardial I/R injury through the enhanced expression of IL-10. Therapies designed to activate iNKT cells might be beneficial to protect the heart from I/R injury.

The AppCare-HF randomized clinical trial: a feasibility study of a novel self-care support mobile app for individuals with chronic heart failure.

Aims: We evaluated a self-care intervention with a novel mobile application (app) in chronic heart failure (HF) patients. To facilitate patient-centred care in HF management, we developed a self-care support mobile app to boost HF patients' optimal self-care. Methods and results: We conducted a multicentre, randomized, controlled study evaluating the feasibility of the self-care support mobile app designed for use by HF patients. The app consists of a self-monitoring assistant, education, and automated alerts of possible worsening HF. The intervention group received a tablet personal computer (PC) with the self-care support app installed, and the control group received a HF diary. All patients performed self-monitoring at home for 2 months. Their self-care behaviours were evaluated by the European Heart Failure Self-Care Behaviour Scale. We enrolled 24 outpatients with chronic HF (ages 31-78 years; 6 women, 18 men) who had a history of HF hospitalization. During the 2 month study period, the intervention group (n = 13) showed excellent adherence to the self-monitoring of each vital sign, with a median [interquartile range (IQR)] ratio of self-monitoring adherence for blood pressure, body weight, and body temperature at 100% (92-100%) and for oxygen saturation at 100% (91-100%). At 2 months, the intervention group's self-care behaviour score was significantly improved compared with the control group (n = 11) [median (IQR): 16 (16-22) vs. 28 (20-36), P = 0.02], but the HF Knowledge Scale, the General Self-Efficacy Scale, and the Short Form-8 Health Survey scores did not differ between the groups. Conclusion: The novel mobile app for HF is feasible.

Enhanced mitochondrial oxidative metabolism in peripheral blood mononuclear cells is associated with fatty liver in obese young adults.

Systemic inflammation underlies the association between obesity and nonalcoholic fatty liver disease (NAFLD). Here, we investigated functional changes in leukocytes' mitochondria in obese individuals and their associations with NAFLD. We analyzed 14 obese male Japanese university students whose body mass index was > 30 kg/m2 and 15 healthy age- and sex-matched lean university students as controls. We observed that the mitochondrial oxidative phosphorylation (OXPHOS) capacity with complex I + II-linked substrates in peripheral blood mononuclear cells (PBMCs), which was measured using a high-resolution respirometry, was significantly higher in the obese group versus the controls. The PBMCs' mitochondrial complex IV capacity was also higher in the obese subjects. All of the obese subjects had hepatic steatosis defined by a fatty liver index (FLI) score ≥ 60, and there was a positive correlation between their FLI scores and their PBMCs' mitochondrial OXPHOS capacity. The increased PBMCs' mitochondrial OXPHOS capacity was associated with insulin resistance, systemic inflammation, and higher serum levels of interleukin-6 in the entire series of subjects. Our results suggest that the mitochondrial respiratory capacity is increased in the PBMCs at the early stage of obesity, and the enhanced PBMCs' mitochondrial oxidative metabolism is associated with hepatic steatosis in obese young adults.

Premedication with pioglitazone prevents doxorubicin-induced left ventricular dysfunction in mice.

BACKGROUND: Doxorubicin (DOX) is widely used as an effective chemotherapeutic agent for cancers; however, DOX induces cardiac toxicity, called DOX-induced cardiomyopathy. Although DOX-induced cardiomyopathy is known to be associated with a high cumulative dose of DOX, the mechanisms of its long-term effects have not been completely elucidated. Pioglitazone (Pio) is presently contraindicated in patients with symptomatic heart failure owing to the side effects. The concept of drug repositioning led us to hypothesize the potential effects of Pio as a premedication before DOX treatment, and to analyze this hypothesis in mice. METHODS: First, for the hyperacute (day 1) and acute (day 7) DOX-induced dysfunction models, mice were fed a standard diet with or without 0.02% (wt/wt) Pio for 5 days before DOX treatment (15 mg/kg body weight [BW] via intraperitoneal [i.p.] administration). The following 3 treatment groups were analyzed: standard diet + vehicle (Vehicle), standard diet + DOX (DOX), and Pio + DOX. Next, for the chronic model (day 35), the mice were administrated DOX once a week for 5 weeks (5 mg/kg BW/week, i.p.). RESULTS: In the acute phase after DOX treatment, the percent fractional shortening of the left ventricle (LV) was significantly decreased in DOX mice. This cardiac malfunction was improved in Pio + DOX mice. In the chronic phase, we observed that LV function was preserved in Pio + DOX mice. CONCLUSIONS: Our findings may provide a new pathophysiological explanation by which Pio plays a role in the treatment of DOX-induced cardiomyopathy, but the molecular links between Pio and DOX-induced LV dysfunction remain largely elusive.

Brain-Derived Neurotrophic Factor Improves Impaired Fatty Acid Oxidation Via the Activation of Adenosine Monophosphate-Activated Protein Kinase-ɑ - Proliferator-Activated Receptor-r Coactivator-1ɑ Signaling in Skeletal Muscle of Mice With Heart Failure.

BACKGROUND: We recently reported that treatment with rhBDNF (recombinant human brain-derived neurotrophic factor) improved the reduced exercise capacity of mice with heart failure (HF) after myocardial infarction (MI). Since BDNF is reported to enhance fatty acid oxidation, we herein conducted an in vivo investigation to determine whether the improvement in exercise capacity is due to the enhancement of the fatty acid oxidation of skeletal muscle via the AMPKα-PGC1α (adenosine monophosphate-activated protein kinase-ɑ-proliferator-activated receptor-r coactivator-1ɑ) axis. METHODS: MI and sham operations were conducted in C57BL/6J mice. Two weeks postsurgery, we randomly divided the MI mice into groups treated with rhBDNF or vehicle for 2 weeks. AMPKα-PGC1α signaling and mitochondrial content in the skeletal muscle of the mice were evaluated by Western blotting and transmission electron microscopy. Fatty acid ß-oxidation was examined by high-resolution respirometry using permeabilized muscle fiber. BDNF-knockout mice were treated with 5-aminoimidazole-4-carboxamide-1-beta-d-riboruranoside, an activator of AMPK. RESULTS: The rhBDNF treatment significantly increased the expressions of phosphorylated AMPKα and PGC1α protein and the intermyofibrillar mitochondrial density in the MI mice. The lowered skeletal muscle mitochondrial fatty acid oxidation was significantly improved in the rhBDNF-treated MI mice. The reduced exercise capacity and mitochondrial dysfunction of the BDNF-knockout mice were improved by 5-aminoimidazole-4-carboxamide-1-beta-d-riboruranoside. CONCLUSIONS: Beneficial effects of BDNF on the exercise capacity of mice with HF are mediated through an enhancement of fatty acid oxidation via the activation of AMPKα-PGC1α in skeletal muscle. BDNF may become a therapeutic option to improve exercise capacity as an alternative or adjunct to exercise training.