Haruyasu Ito

Pioglitazone, a peroxisome proliferator-activated receptor-γ agonist, attenuates myocardial ischemia/reperfusion injury in a rat model

Thiazolidinediones are insulin-sensitizing drugs, ligands for peroxisome proliferator-activated receptor-γ (PPAR-γ), which play an important role in the modulation of inflammatory responses. Myocardial ischemia/reperfusion (MI/R) injury is associated with inflammation, in which various cells, particularly monocytes and macrophages, are involved. This study examined the effects of the thiazolidinedione peroxisome proliferator-activated receptor-γ ligand, pioglitazone, in a rat model of MI/R injury. Pioglitazone at 3 mg/kg/day or the vehicle was administered for 7 days before rats were subjected to 30 minutes of coronary ligation followed by 24 hours of reperfusion. The mRNA expression [monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1] in the ischemic region, the number of infiltrating macrophages in the ischemic region, and the myocardial infarct size were examined. The inhibitory effects of pioglitazone on activated macrophages were studied in vitro. Phorbol 12-myristate 13-acetate–induced MCP-1 production, in the absence or presence of pioglitazone, were assayed in cultured macrophages. Compared with the control group, (1) mRNA levels of MCP-1 and intercellular adhesion molecule-1 and the number of infiltrating macrophages in the ischemic region were significantly lower in the pioglitazone-treated group; and (2) myocardial infarct size was significantly smaller in the pioglitazone-treated group. Phorbol 12-myristate 13-acetate–stimulated cultured macrophages in the presence of pioglitazone produced significantly lower levels of MCP-1 than the stimulated control in the absence of pioglitazone. These observations demonstrate that pioglitazone has anti-inflammatory effects in MI/R injury that are independent of its insulin-sensitizing effect.

Roles and Relationship of Macrophages and Monocyte Chemotactic and Activating Factor/Monocyte Chemoattractant Protein-1 in the Ischemic and Reperfused Rat Heart

Reperfusion injury is a troublesome and unresolved problem in acute myocardial infarction and is believed to be associated with inflammatory reactions in which various types of cells and cytokines participate, in particular, macrophages and monocyte chemoattractant protein-1 (MCP-1). We designed this study to clarify the role and relationship of macrophages and MCP-1 in ischemic and reperfused heart. The number and distribution of macrophages and MCP-1 messenger RNA (mRNA) in the ischemic and reperfused rat heart were examined with in situ hybridization and immunohistochemistry. Myocardial samples were obtained at several times. In situ hybridization was performed with digoxigenin-labeled antisense RNA probe for rat MCP-1 mRNA, and immunohistochemistry was performed with antimacrophage antibody. Double staining with in situ hybridization and immunohistochemistry was also performed. The number of MCP-1 mRNA-positive cells increased after reperfusion and peaked at 3 hours after reperfusion. Early infiltration of ischemic tissues by macrophages was also observed at the time of the absence of an increase of MCP-1 mRNA-positive cells, and this infiltration was not significantly accelerated by reperfusion, but by ischemia itself. The numbers of both MCP-1 mRNA-positive cells and macrophages increased in the ischemic marginal region over time. From the result of double staining, and based on the cellular morphology and the distribution, the majority of MCP-1 mRNA-positive cells appeared to be activated macrophages. This suggests that macrophages may not be attracted to cardiac tissue only by MCP-1 and that MCP-1 may have some roles other than attracting macrophages into ischemic heart. It also suggests that macrophages and MCP-1 may play an important role in reperfusion injury and that MCP-1 may be one of the key molecules of reperfusion injury. These observations may contribute to the development of a new therapeutic approach to the prevention of reperfusion injury.

Measuring serum aminoterminal type III procollagen peptide, 7S domain of type IV collagen, and cardiac troponin T in patients with idiopathic dilated cardiomyopathy and secondary cardiomyopathy

Objective To identify new prognostic indicators in idiopathic dilated cardiomyopathy (DCM) and secondary cardiomyopathy. Design and patients Serum concentrations of aminoterminal propeptides of type III procollagen and the 7S domain of type IV collagen (7S collagen)—which have recently been used as indicators of collagen matrix turnover in other diseases—and of cardiac troponin T were measured in 17 consecutive patients with DCM and in four patients with secondary cardiomyopathy (one associated with hyperthyroidism, two with chronic renal failure, one with amyloidosis), confirmed by endomyocardial biopsy. The correlation of these variables with short term prognosis was then assessed prospectively. Results 11 of the patients were positive for type III procollagen, 7S collagen, or troponin T even though their creatine kinase concentrations were within the normal range. These patients had a poor short term prognosis (p < 0.001). Conclusions Within the DCM and secondary cardiomyopathy groups, there was a subgroup of patients with raised concentrations of serum collagen and troponin T, for whom short term prognosis was poor. Although it is unclear whether these serum peptide levels reflect ongoing myocyte degeneration and interstitial fibrosis, they may serve as useful new prognostic indicators for cardiomyopathy.

Therapeutic effects of FTY720, a new Immunosuppressive agent, in a murine model of acute viral myocarditis

OBJECTIVES This study examines the efficacy of FTY720 (FTY), a new immunosuppressor, in the treatment of acute viral myocarditis in a murine model. BACKGROUND Immunosuppressive agents have no proven therapeutic efficacy in experimental or clinical myocarditis. METHODS Encephalomyocarditis virus was inoculated i.p. in DBA/2 mice on day 0. Postinoculation treatment consisted of FTY 10 mg/kg/day p.o. (FTY group), or cyclosporine A (CsA) 40 mg/kg/day p.o. (CsA group) or distilled water p.o. only (control group). Survival until day 14, as well as cardiac histopathology, virus concentrations, cytokines (interleukin [IL]-2, IL-12, interferon [IFN]-gamma and tumor necrosis factor [TNF]-alpha) and nitric oxide (NO) on day 5 were examined. RESULTS In the control and CsA groups, all mice died within 10 and 7 days, respectively. However, in the FTY group, 27% of the animals survived up to day 14. Compared with the control group, 1) histological scores were significantly lower in the FTY group but unchanged in the CsA group; 2) virus concentration was significantly higher in the CsA group but not in the FTY group; 3) expressions of IL-2, IL-12 and IFN-gamma in the heart were suppressed in both the FTY and CsA groups, though suppression was weaker in the FTY group; 4) TNF-alpha and NO were significantly increased in the CsA group but not in the FTY group. CONCLUSIONS FTY720 had a significant therapeutic effect in acute experimental myocarditis without inducing excessive virus replication. This report is the first to describe a beneficial effect by an immunosuppressive agent in the treatment of acute viral myocarditis.

Liver fibrogenesis marker, 7S domain of collagen type IV in patients with acutely decompensated heart failure: Correlates, prognostic value and time course.

BACKGROUND Congestion in heart failure (HF) induces multiple organ injury, which may cause remodeling of extracellular matrix. We hypothesized that liver fibrogenesis marker, 7S domain of collagen type IV (P4NP 7S) was correlated with congestion and liver injury in HF. METHODS AND RESULTS We measured serum P4NP 7S in two cohorts. Cohort 1 included 70 patients undergoing catheterization. P4NP 7S was correlated with pulmonary capillary wedge pressure, right ventricular and atrial pressure (r=0.50, P<0.001, r=0.42, P<0.001, r=0.39, P=0.001, respectively) but not with cardiac index (r=-0.05. P=0.7). Cohort 2 included 145 patients with acute HF, in whom we serially measured P4NP 7S at admission, discharge, early (1-month) and late (6-month) post-discharge period. γ-Glutamyltransferase and B-type natriuretic peptide were independently correlated with P4NP 7S at discharge. The cumulative 1-year incidence of death or HF hospitalization was much higher in the 3rd tertile of P4NP 7S than in the 1st and 2nd tertiles (50%, 25%, and 24%, Log-rank P=0.004). P4NP 7S enhanced risk classification when added to conventional risk factors (net reclassification improvement=0.47, P=0.02). In patients without early readmission, P4NP 7S decreased during hospitalization and remained low for up to 6months, whereas in patients with early readmission, P4NP 7S was persistently elevated during hospitalization, further increased at second admission, and remained high at 6months. CONCLUSION P4NP 7S was correlated with hemodynamics. The results shed new light on the pathophysiology of HF.

Myocardial Expression Level of Neural Cell Adhesion Molecule Correlates With Reduced Left Ventricular Function in Human Cardiomyopathy

Background— Recently, we screened for cardiac genes induced by metabolic stress and identified neural cell adhesion molecule (NCAM) as a candidate. This study aimed to clarify the expression pattern of NCAM in human cardiomyopathy. Methods and Results— A total of 64 cardiac tissue samples of patients with dilated cardiomyopathy were dichotomized according to the immunohistochemically determined signal intensity of NCAM staining (NCAM-high and NCAM-low groups). Clinical and hemodynamic data of the patients were compared between the 2 groups. Fibrosis area, left ventricular end-diastolic volume index, and left ventricular diastolic pressure were greater in the NCAM-high group (22.8% versus 11.6%, P<0.05; 130.3±57.6 versus 104.8±31.7 mL/m2, P<0.05; 14.3±8.0 versus 8.8±4.7 mm Hg, P<0.005; respectively). Incidence of cardiac death and admission for worsening heart failure was higher in the NCAM-high group during a follow-up of 6.3 years (log-rank P<0.05). Another 18 tissue samples were analyzed to determine the relationships between expression level of NCAM and major metabolic genes as well as hemodynamic parameters. The mRNA level of NCAM correlated with the serum (r=0.58; P=0.01) and mRNA levels (r=0.61; P=0.008) of brain-derived natriuretic peptides. It was also correlated with the mRNA levels of proliferator-activated receptor-&ggr; coactivator-1 &agr; (r=0.69; P=0.002) and the nuclear respiratory factor 1 (r=0.74; P<0.001). Conclusions— Expression of NCAM was associated with worsening hemodynamic parameters and major metabolic genes. Together with our previous findings, these data support the involvement of NCAM in left ventricular remodeling, revealing new insights into the pathophysiology of heart failure.

Elevated circulating levels of tumor necrosis factor in patients with mitral valve disease and ventricular septum defect.

SummaryElevated levels of circulating tumor necrosis factor (TNF)-α have been reported in patients with decreased left ventricular ejection fraction. Also, TNF has been reported to depress myocardial contractility. In our previous study, no correlation was found between the plasma level of TNF and clinical parameters in patients with cardiomyopathy. In the present study, we detected elevated levels of circulating TNF-α in 5 out of 15 patients with mitral valve disease and in 1 patient with ventricular septal defect whose left ventricular ejection fraction was within the normal range. The levels of TNF-α were not correlated with any hemodynamic parameters. Further studies are necessary to clarify the mechanisms of the regulation and effects of TNF-α in patients with chronic heart failure.

Genes of the Major Histocompability Complex Class II Influence the Phenotype of Cardiomyopathies Associated With Hepatitis C Virus Infection

Cardiomyopathies are diseases of the myocardium of known or unknown etiology, including dilated, hypertrophic, restrictive and arrhythmogenic right ventricular cardiomyopathies.1 Although, this classification does not describe the underlying pathologic cause, distinct entities tend to fall into specific anatomic categories. The diagnosis is based primarily on clinical criteria and on the exclusion of an identifiable underlying cause.1 This has complicated the distinction of underlying pathogenic mechanisms, since patients with cardiomyopathies are heterogeneously and to various degrees, affected by genetic, viral, immunologic, and environmental factors.2