The HSP90 inhibitor 17‐DMAG alleviates primary biliary cholangitis via cholangiocyte necroptosis prevention

Abstract Cholangiocyte death accompanied by the progression of primary biliary cholangitis (PBC) has not yet been thoroughly investigated. Thus, we are aimed to explore the role of HSP90 and a potential treatment strategy in cholangiocyte necroptosis. First, we detected the expression of HSP90 and necroptotic markers in liver tissues from patients and mice with PBC by immunohistochemistry (IHC) and real‐time polymerase chain reaction (PCR). Then, the HSP90 inhibitor, 17‐dimethylaminoethylamino‐17‐demethoxygeldanamycin (17‐DMAG), was administered by intraperitoneal injection to evaluate its therapeutic effect for PBC by IHC, real‐time PCR, and western blotting. Human intrahepatic bile duct epithelial cells (HIBECs) were induced to necroptosis by toxic bile acid and lipopolysaccharide (LPS) treatment, and evaluated via Cell Counting Kit‐8 and flow cytometry assays. Additionally, 17‐DMAG, cycloheximide, and a proteasome inhibitor were used to evaluate the role of HSP90 in cholangiocyte necroptosis. We found that the expression of HSP90 was elevated in the cholangiocytes of patients and mice with PBC, along with higher expressions of receptor‐interacting serine/threonine‐protein kinase 1 (RIPK1), RIPK3, mixed lineage kinase domain‐like protein (MLKL), and phosphorylated‐MLKL (p‐MLKL). Proinflammatory cytokines and antibody levels of the E2 subunit of pyruvate dehydrogenase complex decreased after treatment with 17‐DMAG in PBC mice. Meanwhile, RIPK1, RIPK3, phosphorylated‐RIPK3, MLKL, and p‐MLKL protein expressions decreased with 17‐DMAG treatment. In vitro, 17‐DMAG and necrostatin‐1 prevented glycochenodeoxycholic acid and LPS‐induced necroptosis of HIBECs. Immunoprecipitation and high‐performance liquid chromatography–mass spectrometry analysis showed that RIPK1 combined with HSP90. Additionally, the 17‐DMAG treatment reduced the RIPK1 half‐life. Overall, 17‐DMAG might be a potential therapeutic agent for PBC via cholangiocyte necroptosis prevention by accelerating RIPK1 degradation.