Trehalose-Induced Activation of Autophagy Improves Cardiac Remodeling After Myocardial Infarction.

BACKGROUND: Trehalose (TRE) is a natural, nonreducing disaccharide synthesized by lower organisms. TRE exhibits an extraordinary ability to protect cells against different kinds of stresses through activation of autophagy. However, the effect of TRE on the heart during stress has never been tested. OBJECTIVES: This study evaluated the effects of TRE administration in a mouse model of chronic ischemic remodeling. METHODS: Wild-type (WT) or beclin1+/- mice were subjected to permanent ligation of the left anterior descending artery (LAD) and then treated with either placebo or trehalose (1 mg/g/day intraperitoneally for 48 h, then 2% in the drinking water). After 4 weeks, echocardiographic, hemodynamic, gravimetric, histological, and biochemical analyses were conducted. RESULTS: TRE reduced left ventricular (LV) dilation and increased ventricular function in mice with LAD ligation compared with placebo. Sucrose, another nonreducing disaccharide, did not exert protective effects during post-infarction LV remodeling. Trehalose administration to mice overexpressing GFP-tagged LC3 significantly increased the number of GFP-LC3 dots, both in the presence and absence of chloroquine administration. TRE also increased cardiac LC3-II levels after 4 weeks following myocardial infarction (MI), indicating that it induced autophagy in the heart in vivo. To evaluate whether TRE exerted beneficial effects through activation of autophagy, trehalose was administered to beclin 1+/- mice. The improvement of LV function, lung congestion, cardiac remodeling, apoptosis, and fibrosis following TRE treatment observed in WT mice were all significantly blunted in beclin 1+/- mice. CONCLUSIONS: TRE reduced MI-induced cardiac remodeling and dysfunction through activation of autophagy.

Sirt1 regulates aging and resistance to oxidative stress in the heart.

Silent information regulator (Sir)2, a class III histone deacetylase, mediates lifespan extension in model organisms and prevents apoptosis in mammalian cells. However, beneficial functions of Sir2 remain to be shown in mammals in vivo at the organ level, such as in the heart. We addressed this issue by using transgenic mice with heart-specific overexpression of Sirt1, a mammalian homolog of Sir2. Sirt1 was significantly upregulated (4- to 8-fold) in response to pressure overload and oxidative stress in nontransgenic adult mouse hearts. Low (2.5-fold) to moderate (7.5-fold) overexpression of Sirt1 in transgenic mouse hearts attenuated age-dependent increases in cardiac hypertrophy, apoptosis/fibrosis, cardiac dysfunction, and expression of senescence markers. In contrast, a high level (12.5-fold) of Sirt1 increased apoptosis and hypertrophy and decreased cardiac function, thereby stimulating the development of cardiomyopathy. Moderate overexpression of Sirt1 protected the heart from oxidative stress induced by paraquat, with increased expression of antioxidants, such as catalase, through forkhead box O (FoxO)-dependent mechanisms, whereas high levels of Sirt1 increased oxidative stress in the heart at baseline. Thus, mild to moderate expression of Sirt1 retards aging of the heart, whereas a high dose of Sirt1 induces cardiomyopathy. Furthermore, although high levels of Sirt1 increase oxidative stress, moderate expression of Sirt1 induces resistance to oxidative stress and apoptosis. These results suggest that Sirt1 could retard aging and confer stress resistance to the heart in vivo, but these beneficial effects can be observed only at low to moderate doses (up to 7.5-fold) of Sirt1.