Toll-like Receptor 5 Deficiency Diminishes Doxorubicin-induced Acute Cardiotoxicity in Mice

Clinical application of doxorubicin (DOX) is limited by its toxic cardiovascular side effects. Our previous study found that toll-like receptor (TLR) 5 deficiency attenuated cardiac fibrosis in mice. However, the role of TLR5 in DOX-induced cardiotoxicity remains unclear. To further investigate this, TLR5-deficient mice were subjected to a single intraperitoneal injection of DOX to mimic an acute model. Here, we reported that TLR5 expression was markedly increased in response to DOX injection. Moreover, TLR5 deficiency exerted potent protective effects against DOX-related cardiac injury, whereas activation of TLR5 by flagellin exacerbated DOX injection-induced cardiotoxicity. Mechanistically, the effects of TLR5 were largely attributed to direct interaction with spleen tyrosine kinase to activate NADPH oxidase (NOX) 2, increasing the production of superoxide and subsequent activation of p38. The toxic effects of TLR5 activation in DOX-related acute cardiac injury were abolished by NOX2 deficiency in mice. Our further study showed that neutralizing antibody-mediated TLR5 depletion also attenuated DOX-induced acute cardiotoxicity. These findings suggest that TLR5 deficiency attenuates DOX-induced cardiotoxicity in mice, and targeting TLR5 may provide feasible therapies for DOX-induced acute cardiotoxicity.