Ablation of cardiac TIGAR preserves myocardial energetics and cardiac function in the pressure overload heart failure model.

Despite the advances in medical therapy, the morbidity and mortality of heart failure (HF) remain unacceptably high. HF results from reduced metabolism-contraction coupling efficiency, so the modulation of cardiac metabolism may be an effective strategy for therapeutic interventions. Tumor suppressor p53 (TP53) and its downstream target TP53-induced glycolysis and apoptosis regulator (TIGAR) are known to modulate cardiac metabolism and cell fate. To investigate TIGAR's function in HF, we compared myocardial, metabolic, and functional outcomes between TIGAR knockout (TIGAR-/-) mice and wild-type (TIGAR+/+) mice subjected to chronic thoracic transverse aortic constriction (TAC), a pressure-overload HF model. In wild-type mice hearts, p53 and TIGAR increased markedly during HF development. Eight weeks after TAC surgery, the left ventricular (LV) dysfunction, fibrosis, oxidative damage, and myocyte apoptosis were significantly advanced in wild-type than in TIGAR-/- mouse heart. Further, myocardial high-energy phosphates in wild-type hearts were significantly decreased compared with those of TIGAR-/- mouse heart. Glucose oxidation and glycolysis rates were also reduced in isolated perfused wild-type hearts following TAC than those in TIGAR-/- hearts, which suggest that the upregulation of TIGAR in HF causes impaired myocardial energetics and function. The effects of TIGAR knockout on LV function were also replicated in tamoxifen (TAM)-inducible cardiac-specific TIGAR knockout mice (TIGARflox/flox/Tg(Myh6-cre/Esr1) mice). The ablation of TIGAR during pressure-overload HF preserves myocardial function and energetics. Thus, cardiac TIGAR-targeted therapy to increase glucose metabolism will be a novel strategy for HF. NEW & NOTEWORTHY The present study is the first to demonstrate that TP53-induced glycolysis and apoptosis regulator (TIGAR) is upregulated in the myocardium during experimental heart failure (HF) in mice and that TIGAR knockout can preserve the heart function and myocardial energetics during HF. Reducing TIGAR to enhance myocardial glycolytic energy production is a promising therapeutic strategy for HF.

First-in-Man Clinical Pilot Study Showing the Safety and Efficacy of Intramuscular Injection of Basic Fibroblast Growth Factor With Atelocollagen Solution for Critical Limb Ischemia.

BACKGROUND: Therapeutic angiogenesis with basic fibroblast growth factor (bFGF) with atelocollagen was confirmed in a study using a limb ischemia mouse model. Because the number of elderly patients with critical limb ischemia (CLI) is increasing, particularly that caused by arteriosclerosis obliterans (ASO), the development of less invasive angiogenesis therapies desired. Methods and Results: This first-in-man clinical study was designed to assess the safety and efficacy of i.m. injection of bFGF with atelocollagen. Human recombinant bFGF (200 µg), combined with 4.8 mL 3% atelocollagen solution, was prepared and injected into the gastrocnemius muscle of the ischemic leg. The primary endpoint was safety, evaluated on all adverse events over 48 weeks after this treatment. The secondary endpoint was efficacy, evaluated by improvement of ischemic symptoms. No serious procedure-related adverse events were observed during the follow-up period. Visual analogue scale (VAS) score was significantly improved at 4, 24 and 48 weeks compared with baseline (P<0.05), and 7 patients became pain free during the follow-up period. Fontaine classification was improved in 4 of 10 patients at 48 weeks. Cyanotic lesions disappeared in 2 patients at 4 weeks. CONCLUSIONS: I.m. injection of bFGF with atelocollagen is safe and feasible in patients with CLI. Randomized controlled trials are therefore needed to confirm these results.

Activation of PPAR-α in the early stage of heart failure maintained myocardial function and energetics in pressure-overload heart failure.

Failing heart loses its metabolic flexibility, relying increasingly on glucose as its preferential substrate and decreasing fatty acid oxidation (FAO). Peroxisome proliferator-activated receptor α (PPAR-α) is a key regulator of this substrate shift. However, its role during heart failure is complex and remains unclear. Recent studies reported that heart failure develops in the heart of myosin heavy chain-PPAR-α transgenic mice in a manner similar to that of diabetic cardiomyopathy, whereas cardiac dysfunction is enhanced in PPAR-α knockout mice in response to chronic pressure overload. We created a pressure-overload heart failure model in mice through transverse aortic constriction (TAC) and activated PPAR-α during heart failure using an inducible transgenic model. After 8 wk of TAC, left ventricular (LV) function had decreased with the reduction of PPAR-α expression in wild-type mice. We examined the effect of PPAR-α induction during heart failure using the Tet-Off system. Eight weeks after the TAC operation, LV construction was preserved significantly by PPAR-α induction with an increase in PPAR-α-targeted genes related to fatty acid metabolism. The increase of expression of fibrosis-related genes was significantly attenuated by PPAR-α induction. Metabolic rates measured by isolated heart perfusions showed a reduction in FAO and glucose oxidation in TAC hearts, but the rate of FAO preserved significantly owing to the induction of PPAR-α. Myocardial high-energy phosphates were significantly preserved by PPAR-α induction. These results suggest that PPAR-α activation during pressure-overloaded heart failure improved myocardial function and energetics. Thus activating PPAR-α and modulation of FAO could be a promising therapeutic strategy for heart failure.NEW & NOTEWORTHY The present study demonstrates the role of PPAR-α activation in the early stage of heart failure using an inducible transgenic mouse model. Induction of PPAR-α preserved heart function, and myocardial energetics. Activating PPAR-α and modulation of fatty acid oxidation could be a promising therapeutic strategy for heart failure.

Inhibition of p53 preserves Parkin-mediated mitophagy and pancreatic ß-cell function in diabetes.

Mitochondrial compromise is a fundamental contributor to pancreatic ß-cell failure in diabetes. Previous studies have demonstrated a broader role for tumor suppressor p53 that extends to the modulation of mitochondrial homeostasis. However, the role of islet p53 in glucose homeostasis has not yet been evaluated. Here we show that p53 deficiency protects against the development of diabetes in streptozotocin (STZ)-induced type 1 and db/db mouse models of type 2 diabetes. Glucolipotoxicity stimulates NADPH oxidase via receptor for advanced-glycation end products and Toll-like receptor 4. This oxidative stress induces the accumulation of p53 in the cytosolic compartment of pancreatic ß-cells in concert with endoplasmic reticulum stress. Cytosolic p53 disturbs the process of mitophagy through an inhibitory interaction with Parkin and induces mitochondrial dysfunction. The occurrence of mitophagy is maintained in STZ-treated p53(-/-) mice that exhibit preserved glucose oxidation capacity and subsequent insulin secretion signaling, leading to better glucose tolerance. These protective effects are not observed when Parkin is deleted. Furthermore, pifithrin-α, a specific inhibitor of p53, ameliorates mitochondrial dysfunction and glucose intolerance in both STZ-treated and db/db mice. Thus, an intervention with cytosolic p53 for a mitophagy deficiency may be a therapeutic strategy for the prevention and treatment of diabetes.

Pyk2 aggravates hypoxia-induced pulmonary hypertension by activating HIF-1α.

Pulmonary arterial hypertension (PAH) is a refractory disease characterized by uncontrolled vascular remodeling and elevated pulmonary arterial pressure. Although synthetic inhibitors of some tyrosine kinases have been used to treat PAH, their therapeutic efficacies and safeties remain controversial. Thus, the establishment of novel therapeutic targets based on the molecular pathogenesis underlying PAH is a clinically urgent issue. In the present study, we demonstrated that proline-rich tyrosine kinase 2 (Pyk2), a nonreceptor type protein tyrosine kinase, plays a crucial role in the pathogenesis of pulmonary hypertension (PH) using an animal model of hypoxia-induced PH. Resistance to hypoxia-induced PH was markedly higher in Pyk2-deficient mice than in wild-type mice. Pathological investigations revealed that medial thickening of the pulmonary arterioles, which is a characteristic of hypoxia-induced PH, was absent in Pyk2-deficient mice, suggesting that Pyk2 is involved in the hypoxia-induced aberrant proliferation of vascular smooth muscle cells in hypoxia-induced PH. In vitro experiments using human pulmonary smooth muscle cells showed that hypoxic stress increased the proliferation and migration of cells in a Pyk2-dependent manner. We also demonstrated that Pyk2 plays a crucial role in ROS generation during hypoxic stress and that this Pyk2-dependent generation of ROS is necessary for the activation of hypoxia-inducible factor-1α, a key molecule in the pathogenesis of hypoxia-induced PH. In summary, the results of the present study reveal that Pyk2 plays an important role in the pathogenesis of hypoxia-induced PH. Therefore, Pyk2 may represent a promising therapeutic target for PAH in a clinical setting.

Late onset of coronary ostial stenosis following surgical aortic valve replacement in a patient with anomalous origin of the right coronary artery.

Surgical aortic valve replacement (SAVR) in patients with anomalous origination of a coronary artery from the opposite sinus is associated with risk for myocardial ischemia during the perioperative period. [1] However, iatrogenic coronary ostial stenosis (ICOS) generally occurs within the first 6 months after SAVR. We present an unusual case of a 74-year-old man with anomalous origination of the right coronary artery from the left coronary sinus, who developed effort angina due to ICOS 19 months following SAVR and ascending aorta replacement. Angiography and computed tomography were utilized to perform a comparison before and after the procedure. From the results, it was evident that the flattened mild stenosis preoperatively was caused by anomalous origination of a coronary artery from the opposite sinus and progressed to severe stenosis by ICOS after the procedure. The patient was successfully treated with percutaneous coronary intervention. .

Three-layer ultrasonic tissue characterization of the ventricular septum is predictive of prognosis in patients with non-obstructive hypertrophic cardiomyopathy.

AIMS: A necropsy study of patients with hypertrophic cardiomyopathy (HCM) who died at a young age exhibited marked disarray and fibrosis in the mid-wall layer of the left ventricular (LV) myocardium. We assessed ultrasonic tissue characteristics in the three layers of the ventricular septum (VS), and correlated the result with long-term prognosis in HCM. METHODS AND RESULTS: The magnitude of cyclic variation of integrated backscatter (CV-IB) was calculated in the three layers of the VS and the whole aspect of the LV posterior wall in 58 non-obstructive HCM patients and 20 healthy controls. All HCM patients were prospectively followed for an average period of 7.1 years for the occurrence of cardiac death or hospitalization due to heart failure. Each CV-IB of four regions was lower in HCM patients than in controls (all P < 0.01). CV-IB of the VS mid-wall layer was lower in 14 HCM patients with cardiac events than in patients without (5.4 ± 0.6 vs. 7.4 ± 0.5 dB, P = 0.033) although CV-IB of three other regions did not differ between the two groups. The optical cut-off point of %CV-IB <90%, i.e. the ratio of CV-IB in the VS mid-wall layer to the mean value in the layers on both sides, was an independent predictor of cardiac events (hazard ratio, 6.12; 95% confidence interval, 1.62-66.6; P = 0.013), with a positive predictive value of 44% and particularly with a high negative predictive value of 91%. CONCLUSION: Patients with non-obstructive HCM are not likely to undergo cardiac events in the near future, when the CV-IB value is not significantly lower in the VS mid-wall layer than in the layers on both sides.

Chronotropic incompetence and autonomic dysfunction in patients without structural heart disease.

AIMS: An attenuated heart rate response to exercise, termed chronotropic incompetence (CI), has been reported to be an independent predictor of cardiovascular mortality. We examined the change in autonomic function during exercise testing and correlated the results with CI. METHODS AND RESULTS: Exercise testing using a bicycle ergometer was performed in 172 patients who had no evidence of cardiac disease. Chronotropic incompetence was defined as the failure to achieve 85% of the age-predicted maximum heart rate, heart rate reserve <80%, or chronotropic response index <0.80. We analysed the relationship between CI and the change in two components of heart rate variability during exercise testing: high-frequency (HF) component (0.15-0.40 Hz) as an index of vagal modulation and the ratio of low-frequency (LF) component (0.04-0.15 Hz) to HF component as an index of sympathovagal balance. Heart rate variability indexes before exercise were similar in patients with and without CI. Percentage changes after exercise in the ratio of LF to HF component were higher in patients with CI than in those without CI (84 +/- 15 vs. 41 +/- 16%, P < 0.05), whereas percentage changes in an HF component were similar in the two groups. CONCLUSION: Our data suggested that CI in patients without structural heart disease was mainly caused by a pathophysiological condition in which sympathetic activation was not well translated into heart rate increase. Further study is needed to determine the post-synaptic sensitivity of the beta-adrenergic receptor pathway in relation to CI.

Usefulness of peripheral arterial signs in the evaluation of aortic regurgitation.

BACKGROUND: Early diagnosis and optimal timing of surgical repair for chronic aortic regurgitation (AR) are topics of interest, because left ventricular compensation delays the clinical signs of the early stages of left ventricular dysfunction. Various physical signs have been described as indicators of chronic AR, but AR screening can be difficult depending on the proficiency of primary care providers. The recent use of the cardio-ankle vascular index (CAVI) measurement to assess peripheral atherosclerosis may detect AR objectively and simply because its arterial pulse wave configuration is closely related to the physical signs of AR. METHODS: CAVI measurements include pulse pressure (PP), the difference in blood pressures between upper and lower limbs (ABD), ankle-brachial index (ABI), ejection time (ET), and upstroke time (UT). We evaluated the differences in CAVI parameters between AR group and age-matched control group, the relationships between CAVI parameters and the echocardiographic semi-quantitative measurements of AR severity such as left ventricular dimensions (Dd, Ds) and vena contracta (VC), and between the changes in CAVI parameters before and after aortic valve replacement. RESULTS: ABD, PP, ET, ankle systolic pressure and ABI in the AR group were significantly higher than that in the control group. Brachial diastolic pressure and CAVI in the AR group were significantly lower than that in the control group. UT was lower than that in the control group (p=0.05). PP did not correlate with the semi-quantitative AR severity, but ABD was correlated with Dd, Ds, and VC and was negatively correlated with UT. The exaggerated ABD, PP, ET, and ABI were moderated after surgery. CONCLUSIONS: CAVI parameters could be useful in the screening and serial follow-up of AR patients.

Cardiac-Specific Bdh1 Overexpression Ameliorates Oxidative Stress and Cardiac Remodeling in Pressure Overload-Induced Heart Failure.

BACKGROUND: Energy starvation and the shift of energy substrate from fatty acids to glucose is the hallmark of metabolic remodeling during heart failure progression. However, ketone body metabolism in the failing heart has not been fully investigated. METHODS AND RESULTS: Microarray data analysis and mitochondrial isobaric tags for relative and absolute quantification proteomics revealed that the expression of D-ß-hydroxybutyrate dehydrogenase I (Bdh1), an enzyme that catalyzes the NAD+/NADH coupled interconversion of acetoacetate and ß-hydroxybutyrate, was increased 2.5- and 2.8-fold, respectively, in the heart after transverse aortic constriction. In addition, ketone body oxidation was upregulated 2.2-fold in transverse aortic constriction hearts, as determined by the amount of 14CO2 released from the metabolism of [1-14C] ß-hydroxybutyrate in isolated perfused hearts. To investigate the significance of this augmented ketone body oxidation, we generated heart-specific Bdh1-overexpressing transgenic mice to recapitulate the observed increase in basal ketone body oxidation. Bdh1 transgenic mice showed a 1.7-fold increase in ketone body oxidation but did not exhibit any differences in other baseline characteristics. When subjected to transverse aortic constriction, Bdh1 transgenic mice were resistant to fibrosis, contractile dysfunction, and oxidative damage, as determined by the immunochemical detection of carbonylated proteins and histone acetylation. Upregulation of Bdh1 enhanced antioxidant enzyme expression. In our in vitro study, flow cytometry revealed that rotenone-induced reactive oxygen species production was decreased by adenovirus-mediated Bdh1 overexpression. Furthermore, hydrogen peroxide-induced apoptosis was attenuated by Bdh1 overexpression. CONCLUSIONS: We demonstrated that ketone body oxidation increased in failing hearts, and increased ketone body utilization decreased oxidative stress and protected against heart failure.

D-Glutamate is metabolized in the heart mitochondria.

D-Amino acids are enantiomers of L-amino acids and have recently been recognized as biomarkers and bioactive substances in mammals, including humans. In the present study, we investigated functions of the novel mammalian mitochondrial protein 9030617O03Rik and showed decreased expression under conditions of heart failure. Genomic sequence analyses showed partial homology with a bacterial aspartate/glutamate/hydantoin racemase. Subsequent determinations of all free amino acid concentrations in 9030617O03Rik-deficient mice showed high accumulations of D-glutamate in heart tissues. This is the first time that a significant amount of D-glutamate was detected in mammalian tissue. Further analysis of D-glutamate metabolism indicated that 9030617O03Rik is a D-glutamate cyclase that converts D-glutamate to 5-oxo-D-proline. Hence, this protein is the first identified enzyme responsible for mammalian D-glutamate metabolism, as confirmed in cloning analyses. These findings suggest that D-glutamate and 5-oxo-D-proline have bioactivities in mammals through the metabolism by D-glutamate cyclase.

Oxidative post-translational modifications develop LONP1 dysfunction in pressure overload heart failure.

BACKGROUND: Mitochondrial compromise is a fundamental contributor to heart failure. Recent studies have revealed that several surveillance systems maintain mitochondrial integrity. The present study evaluated the role of mitochondrial AAA+ protease in a mouse model of pressure overload heart failure. METHODS AND RESULTS: The fluorescein isothiocyanate casein assay and immunoblotting for endogenous mitochondrial proteins revealed a marked reduction in ATP-dependent proteolytic activity in failing heart mitochondria. The level of reduced cysteine was decreased, and tyrosine nitration and protein carbonylation were promoted in Lon protease homolog (LONP1), the most abundant mitochondrial AAA+ protease, in heart failure. Comprehensive analysis revealed that electron transport chain protein levels were increased even with a reduction in the expression of their corresponding mRNAs in heart failure, which indicated decreased protein turnover and resulted in the accumulation of oxidative damage in the electron transport chain. The induction of mitochondria-targeted human catalase ameliorated proteolytic activity and protein homeostasis in the electron transport chain, leading to improvements in mitochondrial energetics and cardiac contractility even during the late stage of pressure overload. Moreover, the infusion of mitoTEMPO, a mitochondria-targeted superoxide dismutase mimetic, recovered oxidative modifications of LONP1 and improved mitochondrial respiration capacity and cardiac function. The in vivo small interfering RNA repression of LONP1 partially canceled the protective effects of mitochondria-targeted human catalase induction and mitoTEMPO infusion. CONCLUSIONS: Oxidative post-translational modifications attenuate mitochondrial AAA+ protease activity, which is involved in impaired electron transport chain protein homeostasis, mitochondrial respiration deficiency, and left ventricular contractile dysfunction. Oxidatively inactivated proteases may be an endogenous target for mitoTEMPO treatment in pressure overload heart failure.

Masquerading bundle branch block as a marker of poor prognosis.

Masquerading bundle branch block is a rare and unique finding on a 12-lead electrocardiogram, consisting of the pattern of right bundle branch block in the precordial leads and left bundle branch block in the limb leads. We experienced a 77-year-old woman with masquerading bundle branch block. She had been well, but died suddenly 9 months after the diagnosis of masquerading bundle branch block. The presence of masquerading bundle branch block indicates severe degeneration of the conduction system, leading to a poor outcome. .

Intramyocardial calcification in a patient with apical hypertrophic cardiomyopathy.

Intramyocardial calcification is a very rare condition. We report a case of a 72-year-old man with apical hypertrophic cardiomyopathy, who was initially suspected of having a thrombus in the left ventricular apex on echocardiography, but was finally diagnosed as having apical intramyocardial calcification on multidetector computed tomography. The mechanism of developing intramyocardial calcification remains to be elucidated, but the patient has been stable for more than 2 years.

Myocardial perfusion abnormality in the area of ventricular septum-free wall junction and cardiovascular events in nonobstructive hypertrophic cardiomyopathy.

Myocardial perfusion abnormality in the left ventricle is known to be prognostic in patients with hypertrophic cardiomyopathy (HCM). Magnetic resonance imaging and necropsy studies on HCM hearts revealed myocardial lesions predominating in the area of ventricular septum-free wall junction. We assessed perfusion abnormality in this area and correlated it with the prognosis of HCM patients. We performed exercise Tc-99m tetrofosmin myocardial scintigraphy in 55 patients with nonobstructive HCM. Perfusion abnormalities were semiquantified using a 5-point scoring system in small areas of anterior junctions of basal, mid, and apical short axis views in addition to a conventional 17-segment model. All patients were prospectively followed for sudden death, cardiovascular death and hospitalization for heart failure or stroke associated with atrial fibrillation. Cardiovascular events occurred in 10 patients during an average follow-up period of 5.7 years. Stress and rest scores from anterior junction, and conventional summed stress score were significantly higher in patients with cardiovascular events than without (all P < 0.05). Anterior junction stress score of >2 produced a sensitivity of 50% and a specificity of 98% for cardiovascular events and was an independent predictor (hazard ratio 8.33; 95% confidence interval, 1.61-43.5; P = 0.01), with rest scores producing similar values, which were higher than summed stress score of >8 (5.68; 1.23-26.3; P = 0.03). The absence of myocardial perfusion abnormality in the narrow area of anterior junction differentiated HCM patients with low-risk.