Abstract
Irreversible cardiotoxicity limits the clinical application of doxorubicin (DOX). DOX-induced cardiotoxicity has been associated with induction of senescence and activation of the p38 MAPK pathway. Losmapimod (LOSM), an orally active p38 MAPK inhibitor, is an anti-inflammatory agent with cardioprotective effects. Nevertheless, the effect of LOSM against DOX-induced cardiotoxicity has not been reported. In this study, we determined the effects of LOSM on DOX-induced chronic cardiotoxicity in C57BL/6 N mice. Five-week-old C57BL/6 N mice were fed diet containing LOSM (estimated daily intake 12 mg/kg/day) or a control diet for four days. Thereafter, mice were randomized to receive six weekly intraperitoneal injections of either DOX (4 mg/kg) or saline. Three days after the last injection, cardiac function was assessed by trans-thoracic echocardiography. Activation of p38, JNK, and ERK1/2 MAPKs were assessed by immunoblotting in the heart and liver. Gene expressions of senescence, inflammatory, oxidative stress, and mitochondrial function markers were quantified using real-time PCR and serum inflammatory markers were assessed by Luminex. Our results demonstrated that LOSM attenuated p38 MAPK activation, ameliorated DOX-induced cardiac dysfunction, and abrogated DOX-induced expression of the senescence marker p21Cip1. Additionally, LOSM demonstrated anti-inflammatory effects, with reduced cardiac Il-1α and Il-6 gene expression in DOX-treated mice. Systemic inflammation, assessed by serum cytokine levels, showed decreased IL-6 and CXCL1 in both DOX-treated mice and mice on LOSM diet. LOSM significantly increased mitofusin2 gene expression, which may enhance mitochondrial fusion. These findings underscore the potential therapeutic efficacy of p38 MAPK inhibition, exemplified by LOSM, in ameliorating DOX-induced cardiotoxicity, senescence, and inflammation.