A new perspective of triptolide-associated hepatotoxicity: the relevance of NF- ? B and NF- ? B-mediated cellular FLICE-inhibitory protein.

ABSTRACT: Previously, we proposed a new perspective of triptolide (TP)-associated hepatotoxicity: liver hypersensitivity upon lipopolysaccharide (LPS) stimulation. However, the mechanisms for TP/LPS-induced hepatotoxicity remained elusive. The present study aimed to clarify the role of LPS in TP/LPS-induced hepatotoxicity and the mechanism by which TP induces liver hypersensitivity upon LPS stimulation. TNF-? inhibitor, etanercept, was injected intraperitoneally into mice to investigate whether induction of TNF-? by LPS participated in the liver injury induced by TP/LPS co-treatment. Mice and hepatocytes pretreated with TP were stimulated with recombinant TNF-? to assess the function of TNF-? in TP/LPS co-treatment. Additionally, time-dependent NF-?B activation and NF-?B-mediated pro-survival signals were measured in vivo and in vitro. Finally, overexpression of cellular FLICE-inhibitory protein (FLIP), the most potent NF-?B-mediated pro-survival protein, was measured in vivo and in vitro to assess its function in TP/LPS-induced hepatotoxicity. Etanercept counteracted the toxic reactions induced by TP/LPS. TP-treatment sensitized mice and hepatocytes to TNF-?, revealing the role of TNF-? in TP/LPS-induced hepatotoxicity. Mechanistic studies revealed that TP inhibited NF-?B dependent pro-survival signals, especially FLIP, induced by LPS/TNF-?. Moreover, overexpression of FLIP alleviated TP/LPS-induced hepatotoxicity in vivo and TP/TNF-?-induced apoptosis in vitro. Mice and hepatocytes treated with TP were sensitive to TNF-?, which was released from LPS-stimulated immune cells. These and other results show that the TP-induced inhibition of NF-?B-dependent transcriptional activity and FLIP production are responsible for liver hypersensitivity.

SUBMITTER: Yuan Z 

PROVIDER: S-EPMC7280150 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature