[Background] Doxorubicin (DOX) has serious side effects, such as cardiotoxicity. DOX tends to accumulate in the mitochondria of cardiomyocytes and cause cardiotoxicity due to mitochondrial dysfunction. cGAS, a cytoplasmic DNA sensor, synthesizes mitochondria and other self-derived free DNA fragments and induces inflammation and apoptosis via the cGAS/STING/IRF3 pathway. In this study, we identified kampo medicines that inhibit DOX cardiotoxicity via the cGAS/STING/IRF3 pathway.
[Methods & Results] To identify Kampo medicines that inhibit DOX cardiotoxicity, in vitro screening was performed using rat cardiomyoblast H9c2 cells. Approximately 40 kampo medicines were investigated for their inhibitory effect on DOX-induced apoptosis after pretreatment with 100 µg/ml each, and orengedokuto most effectivly inhibit DOX cell death was. Western blotting showed that DOX increased the levels of cleaved caspase-3, IRF3, and STING, whereas orengedokuto suppressed these levels. The cGAS inhibitor RU.521 also inhibited DOX-induced increases in cleaved caspase-3, IRF3, and STING phosphorylation levels. Next, in vivo studies were conducted using a mouse model of DOX cardiotoxicity, in which C57BL/6J mice received a single dose of 20 mg/kg DOX and a daily oral dose of 1 g/kg/day orengedokuto for five consecutive days. DOX induced IL-1β and CXCL10 expression downstream of the cGAS/STING/IRF3 pathway, and the increased expression of cleaved caspase-3 was suppressed by orengedokuto.
[Conclusion] This study indicates that orengedokuto reduces DOX cardiotoxicity via the cGAS/STING/IRF3 pathway.