Transcriptome profile analysis reveals cardiotoxicity of maduramicin in primary chicken myocardial cells

Maduramicin, an excellent ionophore antibiotic, is extensively used to control coccidiosis in poultry. Numerous maduramicin intoxications have been reported in farm animal and human due to its relatively narrow safety range, with necrosis or degeneration of cardiac and skeletal muscles as hallmark. To date, the mechanisms of maduramicin-induced cardiotoxicity remain unclear in chicken and other animals. Maduramicin (5 µg/mL)-treated primary chicken myocardial cells were used for RNA sequencing (RNA-Seq) and bioinformatics analysis in this study. A total of 1442 differential expressed genes were identified. 810 genes were up-regulated and the rest 632 genes were down-regulated. Transcriptome analysis revealed that the cytokine-cytokine receptor interaction, apoptosis, calcium signal and cytoplasmic vacuolization pathways were significantly affected. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis showed that gene expression patterns were consistent with RNA-Seq analysis. Pro-inflammatory cytokines including tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8), apoptosis ratios, cleaved caspase-3, intracellular calcium level and Ca²⁺-ATPase activity were elevated after maduramicin (0.05, 0.5 and 5 µg/mL) treatment. Massive vacuole formation was found in the cytoplasm by morphology and transmission electron microscopy observation. Taken together, the results suggested that maduramicin exerted its cardiotoxicity by multiple molecular mechanisms in primary chicken myocardial cells.