A Novel Angiotensin Type I Receptor Antagonist, Fimasartan, Prevents Doxorubicin-induced Cardiotoxicity in Rats

Angiotensin receptor blockers (ARBs) have organ-protective effects in heart failure and may be also effective in doxorubicin-induced cardiomyopathy (DOX-CMP); however, the efficacy of ARBs on the prevention of DOX-CMP have not been investigated. We performed a preclinical experiment to evaluate the preventive effect of a novel ARB, fimasartan, in DOX-CMP. All animals underwent echocardiography and were randomly assigned into three groups: treated daily with vehicle (DOX-only group, n=22), 5 mg/kg of fimasartan (Low-fima group, n=22), and 10 mg/kg of fimasartan (High-fima group, n=19). DOX was injected once a week for six weeks. Echocardiography and hemodynamic assessment was performed at the 8th week using a miniaturized conductance catheter. Survival rate of the High-fima group was greater (100%) than that of the Low-fima (75%) and DOX-only groups (50%). Echocardiography showed preserved left ventricular (LV) ejection fraction in the High-fima group, but not in the DOX-only group (P=0.002). LV dimensions increased in the DOX-only group; however, remodeling was attenuated in the Low-fima and High-fima groups. Hemodynamic assessment showed higher dP/dt in the High-fima group compared with the DOX-only group. A novel ARB, fimasartan, may prevent DOX-CMP and improve survival rate in a dose-dependent manner in a rat model of DOX-CMP and could be a treatment option for the prevention of DOX-CMP.

Uncleaved Dystrophin Induce Cardiac Myocyte Apoptosis in Coxsackievirus Infected Balb/C Background Mice Heart

It has been previously demonstrated that dystrophin is cleaved in the cardiac myocyte by the viral protease 2A following infection with Coxsackievirus B3 (CVB3). The viral protease 2A mediated cardiomyopathy can be prevented by inhibiting cleavage of dystrophin. However, it is less clear whether uncleaved dysdrophin have other heart protective effect in coxsackievirus infection. To address this, we generated a Balb/C background mouse that had a point mutation in dystrophin that prevents cleavage by protease 2A (KI). We show here that when mice expressing cleavage-resistant dystrophin were infected with CVB3, there was increased cardiac myocyte apoptosis. Bax and Bcl-X(L) mRNA ratio was significantly increased in KI mice heart compare to wild type mice heart. We found cleavage-resistant dystrophin induced the apoptosis related enzyme capspase-3 and caspase-8 activity. In addition, TUNEL stain was observed many TUNEL positive cardiac myocyte in KI mice heart compare to wild type mice heart (3.7% vs 0.3%). However, zVAD treatment for apoptosis blocking was significantly decreased myocardium damage and fibrosis in KI mice heart. These findings indicated that uncleaved dystrophin may have a critical role in cardiac myocyte viral propagation. Uncleaved dystrophin mutant induced cardiac myocyte apoptosis. It delayed coxsackievirus propagation in cardiac myocyte and could prevent cardiac myocyte death.

Cardiac-specific Coxsackievirus and Adenovirus Receptor (CAR) Deletion Inhibit Enterovirus Infection in Murine Heart

The structure of coxsackievirus and adenovirus receptor's CAR is similar to adhesion molecules. In the adult heart, the majority of CAR localizes at the intercalated disc. Germ line CAR deletion induces embryonic lethality at E11.5 with evidence of a cardiac abnormality. The CAR role as a viral receptor is well known; however, its precise function in the heart for enterovirus infection is not clear. To understand the role of CAR in the cardiac myocyte, we generated cardiac-specific CAR knockout mice using a CAR floxed allele and alpha-MHC-Mer CRE Mer mice. Western blot analysis and immunofluorescent stain of ventricles at 6 weeks after 2 weeks tamoxifen administration, CAR expression was significantly decreased in CAR(f/f) MCM mice but not in CAR(f/f) mice heart. Enterovirus was intraperitoneally infected into CAR(f/f) MCM and CAR(f/f) mice (n=10 each). CAR disruption was dramatically reduced virus infection and replication in the heart but not different in liver, spleen, and pancreas. Cardiac myocyte damage was significantly reduced in the CAR(f/f) MCM mutant mice by evans blue dye stain. In addition, the CAR(f/f) MCM mutant mice heart inflammation and fibrosis were decreased in H&E and trichrome stain compare to CAR(f/f) control mice. CAR expression was required for normal ventricular function, but it is the cause of enterovirus infection. In the adult mice heart, CAR deletion was significantly reduced viral infection, proliferation, and myocarditis. These results suggested that CAR deletion could be useful therapeutic strategy to prevent viral myocarditis.

Effects of Cardiotrophin-1 on Adriamycin-Induced Apoptosis in H9c2 Cardiomyoblasts

BACKGROUND AND OBJECTIVES: Adriamycin (doxorubicin, ADR) is a highly effective anti-neoplastic drug, but its clinical use is limited by its adverse side effects on the heart. Cardiotrophin (CT-1), a potent cardiac survival factor, is capable of inhibiting apoptosis in cardiac myocytes. The aim of this study was to investigate the cyto-protective effects of CT-1 against ADR-induced apoptosis in vitro. MATERIALS AND METHODS: We determined a reasonable ADR concentration for inducing cell death by utilizing a cell survival test performed in a dose-dependent manner. To determine the requirements for apoptosis in ADR-treated cardiac myocytes (H9c2 cells), we examined the effect of CT-1 on survival and apoptotic changes using a cell counting kit (CCK), RT-PCR, and Western blotting. RESULTS: In analyzing cell survival as determined by CCK, ADR-induced cell death was found to occur in a dose-dependent manner (50% death at 24 hours after 2 micrometer of ADR), and ADR was shown to decrease procaspase-3. On RT-PCR, expression of Bax-alpha mRNA increased and Bcl-2 decreased during the 24 hours after ADR treatment. Consequently, the ratio of Bax-alpha/Bcl-2 mRNA peaked at 24 hours after ADR treatment. In contrast, CT-1 effectively attenuated the ADR-induced cell death in a dose-dependent manner. The changes in Bax-alpha and Bcl-2 mRNA expression after ADR treatment were reversed by CT-1 (1 ng/mL) treatment. The protein levels of procaspase-3 decreased after ADR treatment, an effect which was reversed by CT-1 treatment. Akt phosphorylation was also increased by CT-1, demonstrating that CT-1 inhibited apoptosis induced by ADR. CONCLUSION: These data demonstrated that ADR-induced apoptosis of cardiomyocytes can be prevented by CT-1; therefore, it may be possible to use CT-1 as a cardioprotective agent during ADR chemotherapy in patients with cancer.

Host Gene Profiling of Coxsackievirus B3 H3- and 10A1-infected Mouse Heart

Coxsackievirus B3 (CVB3) is a non-enveloped virus that has a single-stranded RNA genome. CVB3 induces myocarditis, and ultimately, dilated cardiomyopathy. A myocarditis variant of CVB3 (CVB3 H3) and its antibody-escape mutant (CVB3 10A1) were studied previously; H3 was found to induce myocarditis and 10A1 was found to be attenuated in infected mice. Although amino acid residue 165, located in a puff region of VP2, was found to be altered (i.e., the H3 asparagine was altered to aspartate in 10A1), the detailed mechanism of attenuation was not clearly elucidated. Here, DNA microarray technology was used to monitor changes in mRNA levels of infected mouse hearts after CVB3 H3 and 10A1 infection. This tool was used to elucidate the pathogenic mechanisms of viral infection by understanding virus-host interactions. We identified several genes, including protein tyrosine kinases, Ddr2 and Ptk2, as well as Clqb and Crry, involved in complement reactions, which may be involved in these viral processes. Thus, gene profiling can provide an opportunity to understand host immune responses to viral infection for gene therapy and may contribute to the identification of the target gene that is modified during treatment of viral myocarditis.

Myocardial injury occurs earlier than myocardial inflammation in acute experimental viral myocarditis

Endomyocardial biopsy often fails to show myocardial inflammation for patients with clinically suspected myocarditis. The serum isoforms of troponin T (cTnT) level is a very sensitive marker of myocardial injury and it is elevated even in the absence of myocardial inflammation. We investigated the correlations for myocardial injury, virus titers and inflammation in acute viral infection. Using the murine coxsackievirus group B3 (CVB3) myocarditis model, the histopathologic findings and virus titers in mouse hearts were compared with the serum cTnT levels measured by ELISA at various time points. Viable virus titers in the hearts peaked at 3 days after infection (8.22+/-0.13 log10 PFU/100 mg of heart); they decreased at day 7 and no viable virus was detected from day 14. Myocardial inflammation was minimal at day 3, peaked at day 7 and markedly decreased at day 14. The individual serum TnT levels were significantly increased at day 3 (7.37+/-1.46 ng/ml), persisted to day 7 (0.73+/-0.08 ng/ml), and normalized at day 14. Serum cTnT levels were correlatable with virus titers in the heart (r=0.744, P <0.01), but the serum cTnT levels were not correlated with the degrees of inflammation. Using the less myocarditic strain of CVB3, similar relationships were observed between the changes for the serum cTnT levels and the heart virus titers. During the course of viral infection, myocardial injury precedes the pathologic evidence of inflammation, and the elevated cTnT levels provide evidence of myocardial injury even in the absence of any histologic findings of myocarditis.

A Case of Superimposed Viral Myocarditis in a Patient with Systemic Lupus Erythematosus

Lupus myocarditis is usually treated using immunosuppressive agents, such as high-dose corticosteroids, azathioprine and cyclophosphamide. Viral myocarditis and enteroviruses have been identified as the most common causative agents of myocarditis in lupus patients. Although immunosuppressive therapy has an important role in the treatment of lupus myocarditis, it is not recommended in patients with infectious or post-infectious viral myocarditis, and supportive care is very important in these patients. A 25-year old female patient, with systemic lupus erythematosus, was admitted due to severe dyspnea, and diagnosed as having heart failure. She recovered 7 days after supportive care for heart failure, without Immuno-suppression. Her sera neutralized coxsackievirus B3 (CVB3) in neutralization test, with the horse anti-CVB3 antibody (Ab, ATCC V030-501-560) used as a positive control. The titers for the neutralizing Ab in her sera were 4 times higher than that of the standard control ATCC Ab.

Change of Serum Cardiac Troponin T and Fetal Troponin T Isoform in Rats with Adriamycin-induced Cardiac Injury

BACKGROUND AND OBJECTIVES: Cardiac troponin T (cTnT) has been used as a very sensitive marker of cardiac injury caused by ischaemia, myocarditis, and cardiomyopathy. After cardiac injury, the fetal cTnT isoform expression in the heart and serum cTnT increases. To investigate the increased levels of serum cTnT, and the expression of fetal cTnT isoform in the heart, that can predict myocardial injury, we measured serum cTnT levels and the fetal cTnT isoform expression at various time points during the early phase of myocardial toxicity induced by adriamycin (ADR) in rat. MATERIALS AND METHODS: Male Sprague-Dawley rats were injected, intraperitoneally, with ADR (5 mg/kg) twice a week for 2 weeks. Control rats were injected with saline. Serum cTnT levels were measured by ELISA. The ratio of fetal/adult (F/A) cTnT isoform expression (%) was semi-quantified by RT-PCR using total RNA from frozen hearts. RESULTS: Serum cTnT levels did not increase by 1 week after ADR injection, but increased significantly after 2 weeks. The ratio of F/A cTnT in the heart significantly increased from day 1, peaked at 1 week and persisted until the end of 2 week. CONCLUSION: The expression of the fetal cTnT isoform occurred from 1 day after ADR injection when the serum cTnT levels were still normal. Although the serum cTnT level is a very sensitive, and an early marker, of cardiac damages, the fetal cTnT isoform expression in the endomyocardial biopsy specimen may be a more sensitive and an earlier marker in the ADR-induced myocardial damage.

Role of Calcineurin-Dependent Signaling Pathway on the Left Ventricular Hypertrophy Induced by Pressure Overload

BACKGROUND AND OBJECTIVES: Calcineurin-dependent transcriptional pathway has recently been implicated in cardiac hypertrophy. Whether calcineurin inhibition can prevent the development of pressure-overload left ventricular hypertrophy (LVH) is still controversial. To elucidate this issue, the effects of calcineurin inhibitors on the prevention of pressure-overload LVH were examined in mice. MATERIALS AND METHODS: Pressure overload was induced by transverse aortic contriction (TAC) in 57 ICR mice. Three different doses of CsA (TAC/CsA group, n=21) and FK506 (TAC/FK group, n=20) were administered subcutaneously from -2 to 14 days after surgery and 16 mice were treated with vehicle (TAC group). Another 60 mice were sham-operated and treated with CsA (CsA group, n=19), FK506 (FK group, n=18) or vehicle (Control group, n=23). RESULTS: Two weeks after TAC, the LV weight-to-body weight (LVW/BW) ratio was not significantly different among the Control, CsA and FK groups although it was greater in the TAC group (4.55+/-0.69 mg/g) than in the Control(2.78+/-0.70 mg/g) and other sham-operated groups (p<0.00005). Low-dose CsA (5 mg/kg/day) or FK506 (0.6 mg/kg/day) injection following TAC did not decrease the LVW/BW ratio. However, intermediate-dose and high-dose CsA (25 and 50 mg/kg/day) or FK506 (2 and 6 mg/kg/day) treatment prevented pressure-overload induced LVH and the degree of LVH inhibition was dose-dependent. Interstitial and/or perivascular fibrosis was remarkably decreased by the administration of intermediate and high doses of calcineurin inhibitors for 2 weeks following TAC. CONCLUSION: Taken together, calcineurin inhibitors, CsA and FK506, attenuated pressure-overload LVH response in a dose-dependent fashion. This data indicates that a calcineurin-dependent signaling pathway is crucial in the development of pressure-overload LVH.

Incidence of eNOS gene mutationin Korean patients with coronary artery spasm

BACKGROUND: Coronary artery spasm is an important mechanism in producing myocardial ischemia. But the exact mechanism of the spasm is not well known. We investigated the mutation of endothelial nitric oxide synthase (eNOS) that produce nitric oxide and relationship between eNOS mutation and coronary artery spasm. MATERIALS AND METHODS: Blood were drawn from the patients with angiographically proven coronary artery spasm and normal controls. DNA were extracted and polymerase chain reaction and restriction analysis with Nae I were performed to find T-786--

Incidence of eNOS gene mutationin Korean patients with coronary artery spasm

BACKGROUND: Coronary artery spasm is an important mechanism in producing myocardial ischemia. But the exact mechanism of the spasm is not well known. We investigated the mutation of endothelial nitric oxide synthase (eNOS) that produce nitric oxide and relationship between eNOS mutation and coronary artery spasm. MATERIALS AND METHODS: Blood were drawn from the patients with angiographically proven coronary artery spasm and normal controls. DNA were extracted and polymerase chain reaction and restriction analysis with Nae I were performed to find T-786--

A Case of Histologically Confirmed Coxsackiviral Myocarditis Supported by a Left Ventricular Assist Device

Enteroviruses are the most common agents of myocarditis and have been implicates in the pathogenesis of dilated cardiopmyopathy. There are still discrepancies in the association of enterovirus and myocardial disease, partially due to lack of data on detection of virus antigen or viral culture in the tissue. For the treatment of fulminant myocarditis, aggressive hemodynamic support is warranted because of its excellent long-term prognosis. This 16 year-old girl was admitted because of anterior chest pain for a day. She had flu-like symptoms such as fever, sore throat and cough at 2 weeks ago. Electrocardiogram showed sinus tachycardia and ST segment elevations in lead II, III, aVF and V1-V4. Troponin T was positive and creatinine phosphokinase was elevated (1323 IU/L) at emergency room. On emergency echocardiogram, inferior wall motion was decreased and the ejection fraction (EF) was 70%. Coronary angiogram showed no thrombus and no significant stenosis in coronary artery, and spasm was not induced with ergonovine. Conventional treatment for congestive heart failure with digoxin (0.25 mg daily) and furosemide (20 mg t.i.d) was started under the impression of myocarditis. On the first hospital day, pulmonary edema and signs of shock were developed. The whole left ventricular(LV) wall motion were markedly decreased and EF was less than 20% on echocardiogram. Despite of intra-aortic balloon pump (IABP) for 4 hours, shock and pulmonary edema was progressed. Mechanical circulatory support was started with left ventricular assist device (LVAD, Bio-pump, Medtronic Bio-Medicus, USA). At the time of operation, central venous pressure was 24cmH20, systolic blood pressure was 75mmHg, left atrium(LA) and LV was dilated and the whole wall of LV showed almost akinesia , and LA appendage was biopsied. After 126 hours of LVAD, LV wall motion was restored and EF was 79% on echocardiogram. LVAD was removed 10 days after operation and she was discharged on 23 days of hospitalization without any heart failure symptoms. Immunohistochemistry of LA showed enteroviral VP1 capsid protein (primary antibody; NoVo Castra Laboratory, UK) over the entire LA wall. Her serum neutralized coxsackievirus B3 (CVB3, H3 variant of Woodruff strain) in neutralization test using horse anti-CVB3 (Nancy strain) antibody (ATCC, V030-501-560) as a positive control. The titer of neutralization Ab in her serum of 21 days increased more than 4 times than that of 2 days.