Ethanol potentiates mirtazapine-induced cardiotoxicity by inducing dysfunctional autophagy via HMGB1-dependent Akt/mTOR signaling pathway.

[Display omitted] • Ethanol (EtOH) potentiates mirtazapine(MIR)-induced cardiotoxicity in C57BL/6J mice and in H9c2 cardiomyocytes. • MIR(-plus-EtOH) triggers autophagy induction whereas impaired autophagosome clearance, resulting in dysfunctional autophagy. • HMGB1 is involved in the autophagy dysfunction via Akt/mTOR signaling pathway in MIR(-plus-EtOH)-injured H9c2 cells. Previous surveys have revealed that mirtazapine (MIR), one of the most commonly prescribed antidepressants, is associated with a higher risk of adverse cardiac events compared with other newer antidepressants. Chronic ethanol (EtOH) abuse could also lead to myocardial injuries. Concerning the common comorbidity of major depression and alcohol dependence, combined consumption of MIR and EtOH might be prevalent in patients with depression, resulting in an additive or synergistic cardiotoxic effect. To this end, the present study evaluated cardiotoxicity induced by MIR-plus-EtOH in vivo (male C57BL/6J mice) and in vitro (H9c2 cardiomyoblasts), Further research on the role of autophagy and underlying signaling pathway were carried out in H9c2 cells. We found that EtOH exacerbated MIR-induced cardiotoxicity both in vivo and in vitro. Furthermore, EtOH significantly potentiated MIR-induced dysfunctional autophagy as reflected by upregulated protein levels of LC3-II, p62, Beclin1 and LAMP-1. Pharmacological inhibition of autophagy by 3-methyladenine alleviated MIR-plus-EtOH-induced myocardial injury. High mobility group box 1 (HMGB1) is a positive regulator of autophagy. In our work, HMGB1 knockdown decreased autophagosome accumulation and boosted viability in H9c2 cells. Additionally, HMGB1 blockage markedly upregulated p-Akt/Akt and p-mTOR/mTOR levels which were suppressed in MIR-plus-EtOH treated cells. In general, the present study demonstrates that EtOH potentiates MIR-induced cardiotoxicity which might be attributed to dysfunctional autophagy via inhibiting Akt/mTOR signaling pathway, while HMGB1 knockdown might contribute to improve autophagy flux. [ABSTRACT FROM AUTHOR]