New insight into reactive ductular cells of biliary atresia provided by pathological assessment of SOX9.

BACKGROUND

Biliary atresia (BA) patients may survive until adolescence after effective Kasai procedure (KP). If liver fibrosis progresses even after successful KP, liver transplantation (LTx) is inevitable. Elucidation of its cause and pathophysiology would open the possibility of treating these patients by non-invasive management. SOX9 is a transcription factor that regulates bile duct development and contributes to liver regeneration and fibrosis. To elucidate the role of SOX9 in BA liver, we investigated the SOX9 expression pattern.

METHOD: Immunostaining with anti-SOX9 antibody was done on hepatic specimens obtained at the time of KP or LTx. We analyzed the association of SOX9 expression with clinical data.

RESULTS

In BA livers, SOX9 was expressed in reactive ductular cells (RDCs), mostly with a nuclear-dominant pattern. SOX9 was also ectopically expressed in hepatocytes, which was more conspicuous at the timing of KP than LTx. SOX9 expression level was significantly correlated with age (days) at which KP was performed, AST and WBC count.

CONCLUSIONS

SOX9 may contribute to RDC formation in BA patients, by affecting both RDCs and hepatocytes. SOX9 could be a key molecule to understand the mechanism of RDC formation, and this understanding would provide a therapeutic strategy for effective treatment of BA.