Podophyllotoxin via SIRT1/PPAR /NF-κB axis induced cardiac injury in rats based on the toxicological evidence chain (TEC) concept

The study of cardiotoxicity of drugs has become an important part of clinical safety evaluation of drugs. Podophyllotoxin (PPT), along with its various derivatives and congeners are widely recognized as broad-spectrum pharmacologically active compounds. Clinical cardiotoxicity of PPT and its derivatives are concerning, basic research on the mechanism of cardiotoxicity remained to be insufficient. In the current study, our team's innovative concept of toxicological evidence chain (TEC) was applied to reveal the cardiac toxicity mechanism of podophyllotoxin (PPT) by targeted metabolomics, TMT-based quantitative proteomics and western blot. The injury phenotype evidence (IPE) acquired from the toxicity manifestations including weight and behavior observation of Sprague-Dawley rat. The rat hearts were assessed for damage through histopathological examination, the levels of myocardial enzymes were detected, which were defined as Adverse Outcomes Evidence (AOE). Overall measurements of targeted metabolomics based on energy metabolism and TMT- based quantitative proteomics were obtained after exposure to PPT to acquire to Toxic Event Evidence (TEE). The mechanism of cardiac toxicity based on the integration analysis of proteomics and metabolomics data was speculated, which was verified by Western blot. The results indicate that exposure to PPT may result in pathological alterations and significant elevation of myocardial enzymes in rat hearts. In addition, we found that PPT causes disorders in cardiac energy metabolism, characterized by the energy metabolism fuels down. TMT-based quantitative proteomics reveal that the PPAR (Peroxisome proliferators-activated receptor) signaling pathway deserves further study. It is worth noting that PPT may suppress the expression of SIRT1, subsequently inducing AMPK inhibition, decrease of PGC-1ɑ and PPARɑ and PPARγ protein, resulting in disorders of glucose oxidation, glycolysis and ketone body oxidation metabolism, which together with the increase of p-IKK and p-IҡBɑ expression leading to the nuclear translocation of NF-ҡB p65 from the cytosol lead to inflammation. This study comprehensively evaluated cardiac toxicity of PPT and initially revealed the mechanism of cardiotoxicity that PPT may lead to disorders of mitochondrial oxidation metabolism and inflammation via SIRT1/PPAR /NF-κB axis, resulting in cardiac injury.