Inflammation as a Possible Trigger for Mitoxantrone-Induced Cardiotoxicity: An In Vivo Study in Adult and Infant Mice

Abstract

Mitoxantrone (MTX) is a pharmaceutical drug used in the treatment of several cancers and refractory multiple sclerosis (MS). Despite its therapeutic value, adverse effects may be severe, namely the frequently reported cardiotoxicity, whose mechanisms need further research. This work aimed to assess if inflammation or oxidative stress-related pathways participate in the cardiotoxicity of MTX, using the mouse as an animal model, at two different age periods (infant or adult mice) using two therapeutic relevant cumulative doses. Histopathology findings showed that MTX caused higher cardiac toxicity in adults. In MTX-treated adults, at the highest dose, noradrenaline cardiac levels decreased, whereas at the lowest cumulative dose, protein carbonylation increased and the expression of nuclear factor kappa B (NF-κB) p65 subunit and of M1 macrophage marker increased. Moreover, MTX-treated adult mice had enhanced expression of NF-κB p52 and tumour necrosis factor (TNF-α), while decreasing interleukin-6 (IL-6). Moreover, while catalase expression significantly increased in both adult and infant mice treated with the lowest MTX cumulative dose, the expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and glutathione peroxidase only significantly increased in infant animals. Nevertheless, the ratio of GAPDH to ATP synthase subunit beta decreased in adult animals. In conclusion, clinically relevant doses of MTX caused dissimilar responses in adult and infant mice, being that inflammation may be an important trigger to MTX-induced cardiotoxicity.

Role of Inflammation and Redox Status on Doxorubicin-Induced Cardiotoxicity in Infant and Adult CD-1 Male Mice

“…Thus, mice were treated biweekly with an intraperitoneal (IP) injection with saline solution (NaCl 0.9%, control group) or DOX (DOX group) over three weeks, to reach a total dosage of 18.0 mg/kg. This total dose of DOX corresponds approximately in humans to 100.6 mg/m 2 for infants and 108.9 mg/m 2 for adults [ 18 , 19 , 20 ]. These doses did not exceed the maximum dosage of DOX recommended in humans [ 2 ] and are similar between groups.…”

“…For sacrifice, infant mice were fully anesthetized with 5% isoflurane and exsanguinated 17 days after the last administration (which correspond for infants to ~1.07 human years) while adults suffered the same procedure 7 days (which correspond for adults to ~1.92 human years) after the last administration. Animals’ well-being was considered through a “scoring system” previously described [ 18 ] to assess and minimize their suffering and stress. It is of relevance to mention that, within those periods of sacrifice and after the corresponding correction to “human time” [ 17 ], cardiac dysfunction has been described in humans [ 23 ].…”

“…Histological procedures were performed as previously reported [ 18 ]. Hematoxylin and eosin staining was performed for assessing tissue damage.…”

“…For both staining’s, the slides were examined and photographed with a Carl Zeiss Imager A1 light microscope equipped with an AxioCam MRc 5 digital camera (Oberkochen, Germany). Histopathological evidence of tissue damage was calculated in terms of their severity and incidence in every slide, according to what has been previously published [ 18 , 25 ]. To semi-quantify the severity of the damage caused to the cardiac tissue, the samples were microscopically characterized in a blinded fashion, according to the following parameters: (i) cellular degeneration, (ii) interstitial inflammatory cell infiltration, (iii) necrotic zones, and (iv) loss of tissue organization.…”

“…The severity of cellular degeneration was scored according to the number of cells that showed alterations (dilatation, vacuolization, pyknotic nuclei, and cellular density) in the light microscopy visual field, using a scale from 0 to 3. Tissue necrosis severity, tissue disorganization and inflammatory activity were also scored (from 0 to 3 values) according to the amount of tissue affected [ 18 , 25 ]. Sections stained with Sirius Red were evaluated using ImageJ software (NIH, Bethesda, MD, USA).…”