FXR/SMAD3 Regulates SOX9 to Inhibit Hepatic Fibrosis in Biliary Atresia via Inhibiting Ferroptosis of Hepatic Stellate Cells.

The biological role of SOX9 in biliary atresia (BA) and the underlying mechanisms were unknown, and these were explored in this study. A BA mouse model and TGF-β-treated LX-2 cells were employed for the in vivo and in vitro experiments. QRT-PCR and western blot were employed to examine mRNA expression and protein level; colorimetric kits were employed to detect serum ALT and AST in mice; hematoxylin-eosin (HE) and Masson staining were employed to assess the pathological changes of liver tissues; different assay kits were employed to assess malondialdehyde (MDA), glutathione (GSH), ROS, and Fe²⁺ concentration. Our results revealed that significantly increased SOX9 and TGF-β were observed in the serum of BA children, and significantly increased SMAD3 and decreased FXR were observed in the liver tissues of BA children. Also, SOX9 deletion alleviated liver fibrosis and inhibited ferroptosis in BA mice. The in vitro experiments further revealed that FXR overexpression or SMAD3 deletion down-regulated SOX9 expression to inhibit ferroptosis in TGF-β-treated LX-2 cells, which may depend on the interaction between SOX9 and SLC7A11. This study may provide novel insight into the pathogenesis of BA as well as a new treatment strategy.