Quantitative Proteomics and Targeted Fatty Acids Analysis Reveal the Damage of Triptolide in Liver and Kidney

Triptolide (TP), the major active component in Tripterygium wilfordii Hook. f., is widely used for the treatment of rheumatoid arthritis and autoimmune diseases. However, organ toxicity, especially hepatotoxicity and nephrotoxicity, limits its clinical application. To fully understand the mechanism underlying TP toxicity, iTRAQ-based 2D-LC-MS/MS proteomics is used to detect differentially expressed proteins in the livers and kidneys of mice administered the LD50 dose of TP. Functional annotation revealed that multiple pathways are involved in TP toxicity, including acute-phase response signaling, the antigen presentation pathway, FXR/RXR activation, LPS/IL-1-mediated inhibition of RXR function, and EIF2 signaling. Members of the cytochrome P450 protein family that are involved in fatty acid (FA) metabolism, such as CYP2E1, show significant differences in expression among groups. Additionally, the proteomics data suggested that FAs are involved in TP-induced toxicity. FA analysis is conducted using HPLC-MRM to characterize the differences among various groups exposed to TP for different times. It has been found that 20 FAs in the liver show significant differences in abundance among groups, whereas in the kidneys, six FAs show significant differences in abundance. By integrating the proteomic and targeted FA analyses, it has been found that differently expressed proteins and FAs both participate in pathways including cellular lipolytic activity, peroxisomal fatty acid beta-oxidation, and so on. Our data contribute to understanding the mechanisms underlying TP-induced organ toxicity. The results may help to improve the clinical efficacy and safety of TP in the future.