Cuproptosis of intrahepatic cholangiocytes aggravates primary biliary cholangitis through PDC-E 2 oligomerisation

Background Cuproptosis is a newly-identified mechanism of cell death features dihydrolipoamide S-acetyltransferase (pyruvate dehydrogenase complex E2 subunit (PDC-E2)) aggregation, while PDC-E2 is the immunodominant autoantigen of primary biliary cholangitis (PBC). Relationship between cuproptosis and PBC, as well as therapeutic avenues designed to modulate cuproptosis are largely unknown. Design First, we compared the susceptibility to cuproptosis across a panel of cell lines and examined the correlation between copper levels and pathological features in chronic liver diseases. Subsequently, we investigated the relationship between PDC-E2 oligomerisation and cuproptosis along with its immunological consequences. Next, we performed high-throughput screening for cuproptosis inhibitors in cholangiocytes and elucidated the mechanism by which berberine inhibits cuproptosis. Finally, we evaluated the therapeutic potential of berberine in PBC. Results Cholangiocytes are more susceptible to cuproptosis than hepatocytes due to lower expression of metallothionein. Cuproptosis markers were observed in cholestatic diseases and copper was positively correlated with disease severity in PBC. We observed copper overload-triggered aggregation of PDC-E2 autoantigen. Intriguingly, cuproptosis triggered cholangiocyte to release vesicles containing aggregated PDC-E2, which potently expanded PDC-E2-specific T cells. A widely prescribed medication, berberine, was identified to inhibit cuproptosis. In PBC mouse models, induction of cuproptosis exacerbated cholangitis, accompanied by increased hepatic infiltration of PDC-E2-specific T cells, while berberine intervention mitigated cholangiocyte inflammation. Mechanistically, berberine suppressed cuproptosis through promoting PDC-E2 degradation and reducing tricarboxylic acid cycle flux to bypass PDC-E2 dependency. Finally, berberine ursodeoxycholate improved biochemical parameters in patients with PBC. Conclusion These findings highlight the pivotal role of cholangiocyte cuproptosis in PBC progression, underscoring the therapeutic potential of berberine for inhibiting cuproptosis.