722 natural activators of autophagy protect the heart from dox-induced cardiomyopathy

Abstract Introduction Heart failure is a frequent death cause for oncological patients who received treatment with doxorubicin (DOX). DOX administration inhibits autophagy in cardiomyocytes and causes myocardial damage. Natural activators of autophagy (NAA) such as trehalose, a natural disaccharide, and spermidine, a putrescine-derived polyamine initially isolated from semen, were previously found to be promising candidates to recover the autophagic flux and treat cardiovascular diseases in mice. Hypothesis The administration of natural activators of autophagy protects the heart from DOX-induced myocardial injury. Methods C57BL/6J WT mice were fed ad libitum with trehalose or spermidine in drinking water and received 3 weekly injections of DOX, reaching a final cumulative dose of 15 mg/kg. Echocardiographic, histological and biochemical analyses were performed 6 weeks after the first administration of DOX. Also, in vitro experimentation was performed on neonatal rat primary cardiomyocytes. Results Mice treated with DOX had reduced systolic function (FS: 44±1.05% vs. 34.1±2.33%, n=6-8), but trehalose administration preserved left ventricular fractional shortening (FS: 34.1 [Office1]±2.33% vs. 45.1±0.75%, n=6-8). Autophagy-deficient Beclin1+/- mice had reduced FS and were not protected by trehalose administration (35.4±2.48% vs. 45.1±0.75%, n=7-8). Mice treated with DOX developed fibrosis (0.1±0.08% vs. 8.6±3.5%, n=5), but this effect was reduced in trehalose-fed mice that received DOX (8.6±3.5% vs. 2±0.68%, n=4-5). DOX administration increased the levels of damaged-mitochondria disposal (2.6±0.74 vs. 9.4±1.7 mitophagic bodies per TEM field, n=13) and trehalose administration further boosted this effect (9.4±1.7 vs. 24.1±1.45, n=13). The mRFP-eGFP-Lc3-dots assay was used for evaluating the autophagic flux in neonatal primary cardiomyocytes and a reduction of autophagy was observed in cells treated with DOX (51.9±4.57 vs. 29.9±3.52 red dots per cell, n=34-51), while trehalose recovered the autophagic flux (29.9±3.52 vs. 121.5±8.02 red dots per cell, n=33-34). Mitochondrial biogenesis reporter ‘MitoTimer’ mice that received DOX showed increased levels of biogenesis (0.8±0.38 vs. 3.3±0.9, n=5-6), while mice receiving DOX and trehalose did not (3.3±0.9 vs. 0.3±0.12, n=5-6). Similarly, spermidine preserved systolic function (FS: 29.4±2.03 vs. 39±3.22, n=5-6) and increased myocardial autophagy. Conclusion NAA-mediated mitophagy induction protects the heart from developing DOX-induced cardiomyopathy by disposing of damaged mitochondria. [Office1]Le virgole diventano punti