Recent Advances in the Mechanisms of Cell Death and Dysfunction in Doxorubicin Cardiotoxicity

Ischemic and non-ischemic myocardial injuries at autopsy- an overview for forensic pathologists

Cardiovascular diseases are major causes of morbidity and death worldwide, and most cardiac deaths are related to ischemic injury of the myocardium (myocardial infarction). As underlined in the current clinical definition and classification of myocardial infarctions, not all myocardial injuries are due to ischemia: irreversible injury, ending in necrosis, can be induced also by various other factors, such as infections, immune disorders, physical and chemical agents, and trauma. This is supported by clinical studies showing that elevated serum levels of cardiac troponins, as a measure of myocardial damage, are also a common finding in the non-ischemic types of myocardial injury. Forensic pathologists confronted with autopsy findings suggestive of myocardial injury should therefore realize that both ischemic and non-ischemic forms of myocardial death can be observed, and not only in natural but also non-natural deaths (intoxications, asphyxia, traumatic and iatrogenic deaths, and others). Distinguishing these different types of injuries and underlying diseases or circumstances of death is critical, not only to determine the cause and mechanism of death, but also to help investigate often challenging medico-legal scenarios. This article reviews the broad spectrum of ischemic and non-ischemic myocardial injuries in natural and violent deaths. From this perspective we propose a diagnostic approach to myocardial injuries in a forensic pathology context.

Preventive effect of imperatorin against doxorubicin-induced cardiotoxicity through suppression of NLRP3 inflammasome activation

Cardiotoxicity is one of the major obstacles to anthracycline chemotherapy. Anthracycline cardiotoxicity is closely associated with inflammation. Imperatorin (IMP), a furocoumarin ingredient extracted from Angelica dahurica, might have potential activity in preventing anthracycline cardiotoxicity due to its anti-cancer, anti-inflammatory, anti-oxidant, cardioprotective properties. This study aims to reveal the effect of IMP on doxorubicin (DOX)-induced cardiotoxicity and its underlying mechanism. We established a rat model of DOX-induced cardiotoxicity by intraperitoneal injection with DOX (1.25 mg/kg twice weekly for 6 weeks), and found that both IMP (25 mg/kg and 12.5 mg/kg) and dexrazoxane 12.5 mg/kg relieved DOX-induced reductions in heart weight, change in cardiac histopathology, and elevated serum levels of LDH, AST and CK-MB. Moreover, DOX upregulated mRNA levels of NLRP3, CASP1, GSDMD, ASC, IL-1β and IL-18, elevated protein expressions of NLRP3, ASC, GSDMD-FL, GSDMD-N, pro‑caspase‑1, caspase‑1 p20, pro‑IL‑1β and IL‑1β in heart tissues, as well as increased serum levels of pro-inflammatory cytokines including IL-1β and IL-18, however both of IMP and dexrazoxane suppressed these alterations. In addition, we carried out neonatal rat cardiomyocytes experiments to confirm the results of the in vivo study. Consistently, pretreatment with IMP 25 µg/mL relieved DOX (1 μg/mL)-induced cardiomyocytes injury, including decreased cell viability and reduced supernatant LDH. IMP inhibited DOX-induced activation of NLRP3 inflammasome in cardiomyocytes. In conclusion, IMP had a protective effect against DOX-induced cardiotoxicity via repressing the activation of NLRP3 inflammasome. These findings suggest that IMP may be a promising alternative or adjunctive drug for the prevention of anthracycline cardiotoxicity.

Growth hormone releasing peptide-6 (GHRP-6) prevents doxorubicin-induced myocardial and extra-myocardial damages by activating prosurvival mechanisms

Introduction: Dilated cardiomyopathy (DCM) is a fatal myocardial condition with ventricular structural changes and functional deficits, leading to systolic dysfunction and heart failure (HF). DCM is a frequent complication in oncologic patients receiving Doxorubicin (Dox). Dox is a highly cardiotoxic drug, whereas its damaging spectrum affects most of the organs by multiple pathogenic cascades. Experimentally reproduced DCM/HF through Dox administrations has shed light on the pathogenic drivers of cardiotoxicity. Growth hormone (GH) releasing peptide 6 (GHRP-6) is a GH secretagogue with expanding and promising cardioprotective pharmacological properties. Here we examined whether GHRP-6 administration concomitant to Dox prevented the onset of DCM/HF and multiple organs damages in otherwise healthy rats. Methods: Myocardial changes were sequentially evaluated by transthoracic echocardiography. Autopsy was conducted at the end of the administration period when ventricular dilation was established. Semiquantitative histopathologic study included heart and other internal organs samples. Myocardial tissue fragments were also addressed for electron microscopy study, and characterization of the transcriptional expression ratio between Bcl-2 and Bax. Serum samples were destined for REDOX system balance assessment. Results and discussion: GHRP-6 administration in parallel to Dox prevented myocardial fibers consumption and ventricular dilation, accounting for an effective preservation of the LV systolic function. GHRP-6 also attenuated extracardiac toxicity preserving epithelial organs integrity, inhibiting interstitial fibrosis, and ultimately reducing morbidity and mortality. Mechanistically, GHRP-6 proved to sustain cellular antioxidant defense, upregulate prosurvival gene Bcl-2, and preserve cardiomyocyte mitochondrial integrity. These evidences contribute to pave potential avenues for the clinical use of GHRP-6 in Dox-treated subjects.