Mitsunori Ishino

High-mobility group box 1 restores cardiac function after myocardial infarction in transgenic mice

AIMS High-mobility group box 1 (HMGB1) is a nuclear DNA-binding protein and is released from necrotic cells, inducing inflammatory responses and promoting tissue repair and angiogenesis. To test the hypothesis that HMGB1 enhances angiogenesis and restores cardiac function after myocardial infarction (MI), we generated transgenic mice with cardiac-specific overexpression of HMGB1 (HMGB1-Tg) using alpha-myosin heavy chain promoter. METHODS AND RESULTS The left anterior descending coronary artery was ligated in HMGB1-Tg and wild-type littermate (Wt) mice. After coronary artery ligation, HMGB1 was released into circulation from the necrotic cardiomyocytes of HMGB1-overexpressing hearts. The size of MI was smaller in HMGB1-Tg than in Wt mice. Echocardiography and cardiac catheterization demonstrated that cardiac remodelling and dysfunction after MI were prevented in HMGB1-Tg mice compared with Wt mice. Furthermore, the survival rate after MI of HMGB1-Tg mice was higher than that of Wt mice. Immunohistochemical staining revealed that capillary and arteriole formation after MI was enhanced in HMGB1-Tg mice. CONCLUSION We report the first in vivo evidence that HMGB1 enhances angiogenesis, restores cardiac function, and improves survival after MI. These results may provide a novel therapeutic approach for left ventricular dysfunction after MI.

Diacylglycerol kinase-ε restores cardiac dysfunction under chronic pressure overload: a new specific regulator of Gαq signaling cascade

Galpha(q) protein-coupled receptor (GPCR) signaling pathway, which includes diacylglycerol (DAG) and protein kinase C (PKC), plays a critical role in cardiac hypertrophy. DAG kinase (DGK) catalyzes DAG phosphorylation and controls cellular DAG levels, thus acting as a regulator of GPCR signaling. It has been reported that DGKepsilon acts specifically on DAG produced by inositol cycling. In this study, we examined whether DGKepsilon prevents cardiac hypertrophy and progression to heart failure under chronic pressure overload. We generated transgenic mice with cardiac-specific overexpression of DGKepsilon (DGKepsilon-TG) using an alpha-myosin heavy chain promoter. There were no differences in cardiac morphology and function between wild-type (WT) and DGKepsilon-TG mice at the basal condition. Either continuous phenylephrine infusion or thoracic transverse aortic constriction (TAC) was performed in WT and DGKepsilon-TG mice. Increases in heart weight after phenylephrine infusion and TAC were abolished in DGKepsilon-TG mice compared with WT mice. Cardiac dysfunction after TAC was prevented in DGKepsilon-TG mice, and the survival rate after TAC was higher in DGKepsilon-TG mice than in WT mice. Phenylephrine- and TAC-induced DAG accumulation, the translocation of PKC isoforms, and the induction of fetal genes were blocked in DGKepsilon-TG mouse hearts. The upregulation of transient receptor potential channel (TRPC)-6 expression after TAC was attenuated in DGKepsilon-TG mice. In conclusion, these results demonstrate the first evidence that DGKepsilon restores cardiac dysfunction and improves survival under chronic pressure overload by controlling cellular DAG levels and TRPC-6 expression. DGKepsilon may be a novel therapeutic target to prevent cardiac hypertrophy and progression to heart failure.

Serum YKL-40 Predicts Adverse Clinical Outcomes in Patients With Chronic Heart Failure

BACKGROUND Human cartilage glycoprotein-39 (YKL-40), a novel inflammatory marker, is secreted into circulation by macrophages, neutrophils, chondrocytes, vascular smooth muscle cells and cancer cells. Circulating levels of YKL-40 are related to the degree of inflammation, tissue remodeling, fibrosis, and cancer progression. METHODS AND RESULTS We examined serum YKL-40 levels in 121 patients with chronic heart failure (CHF) and 39 control subjects. The patients were followed up to register cardiac events for a mean of 720 days. Serum YKL-40 levels were measured by sandwich enzyme-linked immunoassay. Serum YKL-40 was significantly higher in New York Heart Association (NYHA) Class III/IV patients than control subjects and NYHA Class I/II patients (P < .0001). Serum YKL-40 was also higher in patients with cardiac events than in event-free patients (P = .0023). Cutoff value of YKL-40 was determined by receiver operating characteristic curve analysis. Kaplan-Meier analysis demonstrated that high level of YKL-40 was associated with higher rates of cardiac events than low levels of YKL-40 (P = .003). The multivariate Cox hazard analysis demonstrated that serum YKL-40 level was an independent prognostic factor of cardiac events (hazard ratio 2.085, 95% confidence interval 1.233-3.499, P < .0048). CONCLUSIONS Serum YKL-40, a new marker of inflammation, was increased in CHF, and YKL-40 detected high risk patients for adverse outcomes in CHF.

Relation of Serum Heat Shock Protein 60 Level to Severity and Prognosis in Chronic Heart Failure Secondary to Ischemic or Idiopathic Dilated Cardiomyopathy

Heat shock protein (HSP) 60 is induced by a variety of stressors, including oxidative stress and inflammation, and it plays a protective role against stress-induced cardiomyocyte injury. Recently, it has been reported that HSP 60 exists in the circulation. Chronic heart failure (CHF) is characterized by systemic abnormalities, and the myocardium is exposed to various stressors. However, the clinical significance of serum HSP 60 has not been examined in CHF. Therefore, the purpose of this study was to examine whether HSP 60 is correlated with the severity of CHF and whether HSP 60 can predict clinical outcomes in patients with CHF. Serum HSP 60 levels were measured in 112 patients with CHF and 62 control subjects. Serum HSP 60 levels were higher in patients with CHF than in control subjects and increased with advancing New York Heart Association functional class. There were 37 cardiac events during a mean follow-up period of 569 +/- 476 days (range 17 to 1,986). Serum HSP 60 levels were higher in patients with cardiac events than in event-free patients. Patients were divided into 4 groups on the basis of HSP 60 level. Cox proportional-hazards regression analysis and Kaplan-Meier analysis revealed that the fourth quartile was associated with the greatest risk for cardiac events. In conclusion, serum HSP 60 level was related to the severity of CHF and associated with a high risk for adverse cardiac events in patients CHF.

8-Hydroxy-2'-deoxyguanosine is a prognostic mediator for cardiac event.

Eur J Clin Invest 2011; 41 (7): 759–766

Long pentraxin PTX3 exacerbates pressure overload-induced left ventricular dysfunction.

Background Left ventricular hypertrophy is enhanced by an inflammatory state and stimulation of various cytokines. Pentraxin 3 (PTX3) is rapidly produced in response to inflammatory signals, and high plasma PTX3 levels are seen in patients with heart failure. This study aimed to examine the influence of PTX3 on cardiac hypertrophy and left ventricular dysfunction with respect to pressure overload. Methods and Results PTX3 systemic knockout (PTX3-KO) mice, transgenic mice with cardiac-specific overexpression of PTX3 (PTX3-TG), and the respective wild-type (WT) littermate mice were subjected to transverse aortic constriction (TAC) or a sham operation. Cardiac PTX3 expression increased after TAC in WT mice. In vitro, hydrogen peroxide induced the expression of PTX3 in both cardiac myocytes and cardiac fibroblasts. Recombinant PTX3 phosphorylated extracellular signal–regulated kinase 1/2 (ERK1/2) in cardiac fibroblasts. Phosphorylation of cardiac ERK1/2 and nuclear factor kappa-B after TAC was attenuated in the PTX3-KO mice but was enhanced in the PTX3-TG mice compared with WT mice. Interleukin-6 and connective tissue growth factor production was lower in the PTX3-KO mice than in the WT mice, but this was augmented in the PTX3-TG mice than in the WT mice. Echocardiography revealed that adverse remodeling with left ventricular dysfunction, as well as with increased interstitial fibrosis, was enhanced in PTX3-TG mice, while these responses were suppressed in PTX3-KO mice. Conclusion The local inflammatory mediator PTX3 directly modulates the hypertrophic response and ventricular dysfunction following an increased afterload.

The role of epicardial adipose tissue in coronary artery disease in non-obese patients

BACKGROUND Epicardial adipose tissue (EAT) surrounding the heart may contribute to the development of coronary artery disease (CAD) through its local secretion of adipocytokines. Although the quantity of EAT is associated with obesity and metabolic syndrome, the role of EAT in the development of CAD in non-obese patients remains to be determined. METHODS This study included 41 patients with CAD who underwent coronary artery bypass graft surgery and 28 patients without CAD who underwent other cardiac surgery. EAT volume was measured by 64-slice multi-detector computed tomography before the surgery. We obtained pericardial fluid and epicardial and subcutaneous adipose tissue samples at the surgery. We investigated the relationship between EAT volume and adiponectin levels in pericardial fluid and incident CAD in patients with and without obesity (body mass index>25 kg/m(2)). RESULTS There was no significant difference in EAT volume between obese patients with and without CAD (55.5 ± 40.2 mL vs. 40.1 ± 19.7 mL, p=0.323). However, EAT volume was significantly greater in non-obese patients with CAD compared to those without CAD (35.0 ± 18.8 mL vs. 15.7 ± 11.0 mL, p<0.001). Adiponectin concentrations in pericardial fluid were significantly lower in non-obese patients with CAD compared to those without CAD (2.7 ± 2.0 μg/mL vs. 4.3 ± 3.7 μg/mL, p=0.049), whereas the adiponectin levels were decreased in obese patients regardless of the presence of CAD. Non-obese patients with CAD had significantly larger size adipocytes in EAT but not subcutaneous adipose tissue compared to those without CAD. Multiple logistic regression analysis showed that increased EAT volume was independently associated with incident CAD in non-obese patients. CONCLUSION Increased EAT may play a crucial role in development of CAD through impairment of adiponectin secretion in non-obese patients.

Serum Midkine as a Predictor of Cardiac Events in Patients With Chronic Heart Failure

BACKGROUND Midkine, a heparin-binding growth factor, has various functions such as migration of inflammatory cell and anti-apoptotic effect. Invasion of inflammatory cell and cardiomyocyte apoptosis are involved in development and progression of heart failure (HF). However, the relationship between midkine and HF has not been previously examined. Therefore, we examined clinical significance of serum midkine levels to determine the prognosis of HF patients. METHODS AND RESULTS Serum levels of midkine were measured at admission in 216 consecutive patients hospitalized for HF and 60 control subjects. Patients were prospectively followed during a mean follow-up period of 653 +/- 375 days with the end points of cardiac death and progressive HF requiring rehospitalization. Serum concentrations of midkine were significantly higher in patients with HF than in controls. Patients with cardiac events had significantly higher concentrations of midkine than those without cardiac events. Kaplan-Meier analysis revealed that cardiac event rates increased markedly as midkine levels rose. Furthermore in the multivariate analysis, after adjustment for age, gender ,and complications, midkine was the independent predictor of cardiac events. CONCLUSION Serum midkine levels are increased in HF patients, and midkine is a novel marker for risk stratifying HF patients.

High serum level of neopterin is a risk factor of patients with heart failure

Serum neopterin concentration was measured in 198 patients with chronic heart failure (CHF) and 62 control subjects by ELISA. Patients were prospectively followed during a median follow-up period of 745 days with end points of cardiac death or re-hospitalization due to progressive heart failure. Serum concentration of neopterin increased with advancing New York Heart Association (NYHA) functional class (P<0.001). High neopterin group had a significantly higher incidence of cardiac events than low neopterin group (P<0.0001). In the multivariate Cox analysis, serum neopterin concentration was an independent risk factor for cardiac events (hazard ratio 1.70, 95%CI 1.16-2.50, P=0.0068). Serum neopterin concentration is a novel prognostic marker for CHF.

Combination of conventional biomarkers for risk stratification in chronic heart failure

BACKGROUND Although there is substantial interest in the use of newer biomarkers to identify patients with chronic heart failure (CHF), recently few investigations have evaluated the incremental usefulness of multiple conventional biomarkers. Combination of several biomarkers simultaneously could enhance risk stratification in CHF. METHODS AND RESULTS We analyzed 7 biomarkers (brain natriuretic peptide, uric acid, sodium, hemoglobin, creatinine, creatinine clearance, high-sensitivity C-reactive protein), which were known as established prognostic markers for CHF, in 154 consecutive CHF patients, and patients were prospectively followed with endpoints of cardiac death or re-hospitalization. When there was an abnormal value, we scored it for one point to calculate multimarker score. Patients were categorized into 3 strata according to multimarker score. There were 83 cardiac events during the follow-up period. A Cox proportional hazard model showed that patients in the high stratum were associated with the highest risk of cardiac events among the 3 strata. Kaplan-Meier analysis revealed that patients in the high stratum had a significantly higher cardiac event rate compared with lower strata. CONCLUSION The combination of conventional biomarkers could potentially improve the risk stratification of CHF patients for the prediction of cardiac events with low cost and wide availability.