The Role of Nrf2 and Inflammation on the Dissimilar Cardiotoxicity of Doxorubicin in Two-Time Points: a Cardio-Oncology In Vivo Study Through Time

Abstract

Doxorubicin (DOX) is a topoisomerase II inhibitor used in cancer therapy. Despite its efficacy, DOX causes serious adverse effects, such as short- and long-term cardiotoxicity. This work aimed to assess the short- and long-term cardiotoxicity of DOX and the role of inflammation and antioxidant defenses on that cardiotoxicity in a mice model. Adult CD-1 male mice received a cumulative dose of 9.0 mg/kg of DOX (2 biweekly intraperitoneal injections (ip), for 3 weeks). One week (1W) or 5 months (5M) after the last DOX administration, the heart was collected. One week after DOX, a significant increase in p62, tumor necrosis factor receptor (TNFR) 2, glutathione peroxidase 1, catalase, inducible nitric oxide synthase (iNOS) cardiac expression, and a trend towards an increase in interleukin (IL)-6, TNFR1, and B-cell lymphoma 2 associated X (Bax) expression was observed. Moreover, DOX induced a decrease on nuclear factor erythroid-2 related factor 2 (Nrf2) cardiac expression. In both 1W and 5M, DOX led to a high density of infiltrating M1 macrophages, but only the 1W-DOX group had a significantly higher number of nuclear factor κB (NF-κB) p65 immunopositive cells. As late effects (5M), an increase in Nrf2, myeloperoxidase, IL-33, tumor necrosis factor-α (TNF-α), superoxide dismutase 2 (SOD2) expression, and a trend towards increased catalase expression were observed. Moreover, B-cell lymphoma 2 (Bcl-2), cyclooxygenase-2 (COX-2), and carbonylated proteins expression decreased, and a trend towards decreased p38 mitogen-activated protein kinase (MAPK) expression were seen. Our study demonstrated that DOX induces adverse outcome pathways related to inflammation and oxidative stress, although activating different time-dependent response mechanisms. Graphical Abstract

The Metabolic Fingerprint of Doxorubicin-Induced Cardiotoxicity in Male CD-1 Mice Fades Away with Time While Autophagy Increases

“…Actually, similar results were found in the short-term paradigm, which may be derived by the low (but clinically relevant) cumulative dose used herein (9 mg/kg). Nonetheless, histologically, heart damage was still evident even five months after DOX administration, as seen and quantified previously by our group [19], indicating the relevance of this dosage to impact the cardiac tissue, despite serum markers seeming to not be modulated at this stage.…”

“…Thus, this finding for albumin concentration may suggest tendency to an increased inflammatory response, and DOX-induced cardiotoxic mechanisms were previously associated with increased inflammation [14,15,35], but we do not overrule other mechanisms. Indeed, histologic cardiac damage was observed after one week of DOX exposure, as seen and quantified in a previous work of the group [19], showing that serum biomarkers are not as sensitive as one could hope for.…”

“…Moreover, DOX2 animals presented cytoplasm vacuolization and large and uncondensed nuclei. For more detailed information and quantification regarding the histological assessment, consult the following paper [19].…”

“…Following blood collection, the hearts were excised and weighed. The heart apex was used for the histological analysis that was carried out as previously described [19,51]. After hematoxylin and eosin staining, the images were taken with a Carl Zeiss Imager A1 light microscope equipped with an AxioCam MRc 5 digital camera (Oberkochen, Germany) to assess tissue damage.…”