Xanthine oxidase inhibition attenuates doxorubicin-induced cardiotoxicity in mice

Accumulating evidence suggests that high serum uric acid (UA) is associated with left ventricular (LV) dysfunction. Although xanthine oxidase (XO) activation is a critical regulatory mechanism of the terminal step in ATP and purine degradation, the pathophysiological role of cardiac tissue XO in LV dysfunction remains unclear. We herein investigated the role and functional significance of tissue XO activity in doxorubicin-induced cardiotoxicity. Either doxorubicin (10 mg/kg) or vehicle was intraperitonially administered in a single injection to mice. Mice were treated with or without oral XO-inhibitors (febuxostat 3 mg/kg/day or topiroxostat 5 mg/kg/day) for 8 days starting 24 h before doxorubicin injection. Cardiac tissue XO activity measured by a highly sensitive assay with liquid chromatography/mass spectrometry and cardiac UA content were significantly increased in doxorubicin-treated mice at day 7 and dramatically reduced by XO-inhibitors. Accordingly, XO-inhibitors substantially improved LV ejection fraction (assessed by echocardiography) and LV developed pressure (assessed by ex vivo Langendorff heart perfusion) impaired by doxorubicin administration. This was associated with an increase in XO-derived hydrogen peroxide production with concomitant upregulation of apoptotic and ferroptotic pathways, all of which were reduced by XO-inhibitors. Furthermore, metabolome analyses revealed enhanced purine metabolism in doxorubicin-treated hearts, and XO-inhibitors suppressed the serial metabolic reaction of hypoxanthine-xanthine-UA, the paths of ATP and purine degradation. In summary, doxorubicin administration induces cardiac tissue XO activation associated with impaired LV function. XO-inhibitors attenuate doxorubicin-induced cardiotoxicity through inhibition of XO-derived oxidative stress and cell death signals as well as the maintenance of cardiac energy metabolism associated with modulation of the purine metabolic pathway.