Background-Tumor necrosis factor-␣ (TNF-␣) and angiotensin II (Ang II) are implicated in the development and further progression of heart failure, which might be, at least in part, mediated by the production of reactive oxygen species (ROS). However, the cause and consequences of this agonist-mediated ROS production in cardiac myocytes have not been well defined. Recently, we demonstrated that increased ROS production was associated with mitochondrial DNA (mtDNA) damage and dysfunction in failing hearts. We thus investigated whether the direct exposure of cardiac myocytes to TNF-␣ and Ang II in vitro could induce mtDNA damage via production of ROS. Methods and Results-TNF-␣ increased ROS production within cultured neonatal rat ventricular myocytes after 1 hour, as assessed by 2Ј,7Ј-dichlorofluorescin diacetate fluorescence microscopy. TNF-␣ also decreased mtDNA copy number by Southern blot analysis in association with complex III activity, which was prevented in the presence of the antioxidant ␣-tocopherol. A direct exposure of myocytes to H 2 O 2 caused a similar decrease in mtDNA copy number. In contrast, Ang II did not affect mtDNA copy number, despite the similar increase in ROS production. TNF-␣-mediated ROS production and a decrease in mtDNA copy number were inhibited by the sphingomyelinase inhibitor D609. Furthermore, N-acetylsphingosine (C2-ceramide), a synthetic cell-permeable ceramide analogue, increased myocyte ROS production, suggesting that TNF-␣-mediated ROS production and subsequent mtDNA damage were mediated by the sphingomyelin-ceramide signaling pathway. Conclusions-The intimate link between TNF-␣, ROS, and mtDNA damage might play an important role in myocardial remodeling and failure.

. Targeted deletion of MMP-2 attenuates early LV rupture and late remodeling after experimental myocardial infarction. Am J Physiol Heart Circ Physiol 285: H1229-H1235, 2003. First published May 29, 2003 10.1152/ ajpheart.00207.2003.-Matrix metalloproteinase-2 (MMP-2) is prominently overexpressed both after myocardial infarction (MI) and in heart failure. However, its pathophysiological significance in these conditions is still unclear. We thus examined the effects of targeted deletion of MMP-2 on post-MI left ventricular (LV) remodeling and failure. Anterior MI was produced in 10-to 12-wk-old male MMP-2 knockout (KO) and sibling wild-type (WT) mice by ligating the left coronary artery. By day 28, MI resulted in a significant increase in mortality in association with LV cavity dilatation and dysfunction. The MMP-2 KO mice had a significantly better survival rate than WT mice (56% vs. 85%, P Ͻ 0.05), despite a comparable infarct size (50 Ϯ 3% vs. 51 Ϯ 3%, P ϭ not significant), heart rate, and arterial blood pressure. The KO mice had a significantly lower incidence of LV rupture (10% vs. 39%, P Ͻ 0.05), which occurred within 7 days of MI. The KO mice exerted less LV cavity dilatation and improved fractional shortening after MI by echocardiography. The LV zymographic MMP-2 level significantly increased in WT mice after coronary artery ligation; however, this was completely prevented in KO mice. In contrast, the increase in the LV zymographic MMP-9 level after MI was similar between KO and WT mice. MMP-2 activation is therefore considered to contribute to an early cardiac rupture as well as late LV remodeling after MI. The inhibition of MMP-2 activation may therefore be a potentially useful therapeutic strategy to manage post-MI hearts. matrix metalloproteinase; cardiac rupture; heart failure; myocyte; extracellular matrix; mouse MYOCARDIAL INFARCTION (MI) leads to complex structural alterations (remodeling) involving both the infarcted and noninfarcted left ventricular (LV) myocardium (21). Early remodeling as LV cavity dilatation occurs during the early phase of MI, which is likely due to wall thinning in the infarct region. This might lead to a cardiac rupture, thereby accounting for the 5-30% of in-hospital mortality after acute MI (1). During the first several days, LV enlargement follows, and, thereafter, a progressive dilatation of the noninfarcted LV occurs over weeks (21). These progressive changes in LV geometry contribute to the development of depressed cardiac function, clinical heart failure, and increased mortality. Accordingly, it is of critical importance to explore the mechanisms of LV remodeling and develop therapeutic strategies that will effectively inhibit this deleterious process.The dynamic synthesis and breakdown of extracellular matrix (ECM) proteins play an important role in post-MI LV remodeling. In particular, the increased expression and activation of matrix metalloproteinases (MMPs) have been implicated in this process (4,5). Several studies have demonstrated that MMPs are involved not...

The activation of TGF-beta is protective against ischemic myocardial damage during the early phase. However, the beneficial effects might be lost, when its expression is sustained, thereby leading to LV remodeling and failure after MI.

Background-Short-term administration of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, statins, has been shown to attenuate ischemia-reperfusion injury. However, the effects of long-term administration of statins on left ventricular (LV) remodeling and failure after myocardial infarction remain unknown. Methods and Results-Mice were subjected to coronary artery ligation and were treated for 4 weeks with vehicle or fluvastatin (10 mg/kg per day PO). Fluvastatin increased survival (61% versus 86%; PϽ0.05) without affecting the infarct size (52Ϯ2% versus 49Ϯ3%; PϭNS). Fluvastatin not only attenuated LV dilatation but also decreased LV end-diastolic pressure and lung weight. Furthermore, it reduced cardiac myocyte hypertrophy and interstitial fibrosis of the noninfarcted LV and also improved LV ejection performance. LV matrix metalloproteinase (MMP)-2 and MMP-13 were increased in myocardial infarction, which was attenuated in fluvastatin-treated mice. Conclusions-Fluvastatin increased survival in a murine model of postinfarct heart failure, which was associated with the amelioration of LV structural remodeling and contractile failure. Moreover, these effects were associated with the attenuation of increased MMP activity. Thus, long-term treatment with fluvastatin might be beneficial also in patients with heart failure and might improve their long-term survival.

Background-Oxidative stress plays an important role in the pathophysiology of heart failure. We determined whether the overexpression of glutathione peroxidase (GSHPx) could attenuate left ventricular (LV) remodeling and failure after myocardial infarction (MI). Methods and Results-We created MI in 12-to 16-week-old, male GSHPx transgenic mice (TGϩMI) and nontransgenic wild-type littermates (WTϩMI) by ligating the left coronary artery. GSHPx activity was increased in the hearts of TG mice, with no significant changes in other antioxidant enzymes. LV concentrations of thiobarbituric acid-reactive substances measured in TGϩMI at 4 weeks were significantly lower than those in WTϩMI. The survival rate during 4 weeks of MI was significantly higher in TGϩMI than in WTϩMI, although the infarct size was comparable. LV cavity dilatation and dysfunction were significantly attenuated in TGϩMI. LV end-diastolic pressure was increased in WTϩMI and reduced in TGϩMI. Improvement of LV function in TGϩMI was accompanied by a decrease in myocyte hypertrophy, apoptosis, and interstitial fibrosis in the noninfarcted LV. Myocardial matrix metalloproteinase-9 zymographic and protein levels were increased in WTϩMI after 3 days but were attenuated in TGϩMI. Conclusions-Overexpression of GSHPx inhibited LV remodeling and failure after MI. Therapies designed to interfere with oxidative stress might be beneficial to prevent cardiac failure.

Background-Increased expression of monocyte chemoattractant protein-1 (MCP-1) has recently been described in clinical and experimental failing heart. However, its pathophysiological significance in heart failure remains obscure. We thus determined whether MCP-1 is increased in post-myocardial infarction (MI) hearts and its blockade can attenuate the development of left ventricular (LV) remodeling and failure. Methods and Results-Anterior MI was produced in mice by ligating the left coronary artery. After 4 weeks, MI mice exerted LV dilatation and contractile dysfunction in association with myocyte hypertrophy and interstitial fibrosis of noninfarcted LV. MCP-1 mRNA levels were increased by 40-fold in noninfarcted LV 1 day after ligation, which persisted until 28 days. To block the MCP-1 signals, an N-terminal deletion mutant of the human MCP-1 gene was transfected into the limb skeletal muscle 3 days before and 14 days after ligation. This method improved the survival rate of mice with MI at 4 weeks (61% versus 87%, PϽ0.05) as well as attenuated LV cavity dilatation and contractile dysfunction, interstitial fibrosis, recruitment of macrophages, and myocardial gene expression of tumor necrosis factor-␣ and transforming growth factor-␤ compared with the nontreated MI mice despite the comparable infarct size calculated as percent LV circumference. Conclusions-The

Background-Peroxisome proliferator-activated receptor-␥ activators have recently been implicated as regulators of cellular proliferation and inflammatory response such as cytokine expression. Because proinflammatory cytokines play a critical role in left ventricular (LV) remodeling after myocardial infarction (MI), we examined the effects of pioglitazone treatment in an experimental model of chronic heart failure. Methods and Results-Mice with extensive anterior MI were treated with placebo or pioglitazone (3 mg · kg Ϫ1 · d

To evaluate the ability of high-resolution computed tomography (HRCT) to detect longitudinal changes in structural abnormalities caused by smoking, HRCT and pulmonary function tests were used to examine nonsmokers, current smokers, and past smokers annually for 5 yr. Inspiratory HRCT was taken for the upper, middle, and lower lung fields, while expiratory images were obtained for the upper and lower lung fields only. We estimated the three quantitative CT parameters including MLD (mean CT value), HIST (CT value with the most frequent appearance), and %LAA (relative area of low attenuation with CT values less than -912 HU). Most of the pulmonary function tests, excepting FEV(1), did not change annually, whereas many of the inspiratory HRCT parameters did. In nonsmokers, only %LAA in the middle or lower lung fields exhibited an annual increase. In current smokers, %LAA in the upper lung field was augmented, while inspiratory MLD or HIST in the middle or lower lung field became more positive. In past smokers, %LAA in any lung field examined increased. The annual change in %LAA in the upper lung field was larger for past smokers than nonsmokers, with little difference between past and current smokers. Expiratory CT parameters showed few annual changes in all groups. In conclusion, (1) aging increases airspace abnormalities, mainly in the lower lung field; (2) although continuous smoking worsens airspace abnormalities mainly in the upper portion of the lung, this trend does not seem to slow down even after smoking cessation; and (3) inspiratory HRCT images are superior to expiratory images for longitudinal estimation of structural abnormalities caused by aging and smoking.